Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 01/30/13


AREA FORECAST DISCUSSION
NWS TUCSON AZ
157 PM MST MON JAN 28 2013 .SYNOPSIS...A WEATHER SYSTEM WILL CONTINUE TO BRING GUSTY WINDS AS WELL AS A CHANCE OF VALLEY RAIN AND MOUNTAIN SNOW THROUGH TONIGHT. COLD TUESDAY MORNING AND WEDNESDAY MORNING. EXPECT DRY CONDITIONS TO RETURN THE SECOND HALF OF THE WEEK ALONG WITH WARMER TEMPERATURES. && .DISCUSSION...THE SURFACE COLD FRONT WAS MOVING THROUGH COCHISE AND GRAHAM COUNTIES AS OF EARLY THIS AFTERNOON. THE SNOW LEVEL WAS STILL BETWEEN 6000 AND 7000 FEET MOST AREAS...BUT WILL LOWER AS THE EVENING GOES ON AND ESPECIALLY OVERNIGHT DOWN TO NEAR 3500 FEET. SHOWERS HAD NOT BEEN TOO WIDESPREAD AS EXPECTED...SO WILL MAINTAIN THE SCATTERED TYPE WORDING AND POP VALUES FOR THIS EVENING AND TONIGHT. ALREADY SEEING SKIES PARTIALLY CLEARING BEHIND THE SURFACE COLD FRONT ACROSS WESTERN PIMA COUNTY...BUT LATEST RAP AND HRRR GUIDANCE SHOWING A FEW SHOWERS EVEN ACROSS THE CENTRAL/WESTERN DESERTS AS THE TROUGH AXIS MOVES THROUGH TONIGHT. SKIES SHOULD GRADUALLY BEGIN TO CLEAR LATE TONIGHT. THE GUSTY WINDS WILL BE DIMINISHING THROUGH THE EVENING HOURS ONCE THE SURFACE FRONT PASSES BY. CLEARING SKIES LATE TONIGHT...ALONG WITH COLDER AIR FILTERING INTO THE AREA WILL RESULT IN COLDER OVERNIGHT LOWS TUESDAY MORNING. WITH STRONG NORTHWEST FLOW ALOFT...GUSTY WINDS ARE EXPECTED ESPECIALLY FOR THE UPPER GILA RIVER VALLEY TUESDAY AND LATER SHIFTS MAY NEED TO CONSIDER A WIND ADVISORY. BY WEDNESDAY AND THURSDAY MORNINGS...A SEASONABLE LIGHT FREEZE FOR THE LOWER DESERTS WILL BE POSSIBLE. OTHERWISE...A RIDGE OF HIGH PRESSURE WILL BRING DRY CONDITIONS AND A RAPID REBOUND IN AFTERNOON TEMPERATURES THE SECOND HALF OF THE WEEK. THEREAFTER... MEDIUM RANGE MODELS SHOWED A SYSTEM AFFECTING THE AREA AROUND SUNDAY INTO EARLY MONDAY WITH PRECIPITATION POSSIBLE. && .AVIATION...BKN-OVC CLOUDS 5-8K FT AGL AND MTNS OBSCD...WITH SCT -SHRA/SHSN THRU TONIGHT...THEN SKIES GRADUALLY CLEARING TUESDAY MORNING. WINDS GENERALLY WLY-SWLY 12-22 KTS WITH HIGHER GUSTS EAST OF TUCSON THROUGH 06Z TUESDAY...THEN MAINLY LESS THAN 10 KTS THROUGH TUESDAY MORNING FROM KTUS WESTWARD AND 10-20 KTS ACROSS EASTERN AREAS. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...NO FIRE WEATHER CONCERNS. SCATTERED SHOWERS AND BREEZY CONDITIONS INTO THIS EVENING. STRONGEST WINDS WILL BE FOR EASTERN COCHISE COUNTY WHERE GUSTS ABOVE 35 MPH ARE POSSIBLE THROUGH LATE AFTERNOON. DRY WEATHER TUESDAY BUT WINDY ESPECIALLY IN THE UPPER GILA RIVER VALLEY. TEMPERATURES WILL BEGIN TO MODERATE WEDNESDAY WITH DRY CONDITIONS CONTINUING. && .TWC WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY TIL 11 PM TONIGHT FOR AZZ510 && $$ VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
AREA FORECAST DISCUSSION
NWS TUCSON AZ
240 AM MST MON JAN 28 2013 .SYNOPSIS...ANOTHER WEATHER SYSTEM WILL BRING GUSTY WINDS AS WELL AS A CHANCE OF VALLEY RAIN AND MOUNTAIN SNOW TODAY AND TONIGHT. COLD TUESDAY MORNING AND WEDNESDAY MORNING. EXPECT DRY CONDITIONS TO RETURN THE SECOND HALF OF THE WEEK ALONG WITH WARMER TEMPERATURES. && .DISCUSSION...COLD FRONT PUSHING INTO FAR WESTERN PIMA COUNTY AS OF 2AM. SOUTHWESTERLY FLOW INCREASING JUST AHEAD OF IT WITH BANDS AHEAD OF THE FRONT STILL MAINLY NORTH. NAM12 AND HRRR CONTINUE TO SHOW ADDITIONAL SHOWER DEVELOPMENT AHEAD OF AND WITH THE FRONT AS IT PUSHES THROUGH OUR CWA TODAY. CONSIDERING NARROW WINDOW WITH PRECIP ASSOCIATED WITH THE FRONT AND FAIRLY RAPID CLEARING BEHIND IT THE EVENING SHIFT INDICATED THIS WITH 3 HR INCREMENTS TO THE POP GRIDS. WE TWEAKED THIS BASED ON 06Z NAM...HRRR TRENDS AND LATEST ECMWF INPUT...BUT HAVE LARGELY KEPT THESE INTACT. SNOW LEVELS CURRENTLY NEAR 7-8K FEET WILL FALL QUICKLY WITH THE FRONT TO 4500 FEET THIS AFTERNOON AND LOWER THIS EVENING...HOWEVER BY THEN THE BEST MOISTURE WILL BE EAST OF OUR AREA. STILL UNABLE TO SQUEEZE OUT WIDESPREAD ADVISORY LEVEL SNOWS WITH 3 TO 6 INCHES EXPECTED ABOVE 7000 FEET TODAY AND TONIGHT...1 TO 3 INCHES BETWEEN 5000 AND 7000 FEET...AND A LIGHT DUSTING TO 1 INCH POSSIBLE BETWEEN 3500 AND 5000 FEET. WE`LL MONITOR PRECIP TRENDS CLOSELY TO VERIFY THIS WHILE ALSO WATCHING FOR ANY MODERATE TO HEAVY PRECIP THAT MAY BRING LOCALIZED FLOODING CONCERNS WHEN ADDED TO SATURDAY`S HEAVY PRECIP TOTALS. GUSTY WINDS TODAY MAINLY AHEAD OF THE FRONT BUT SHOULD REMAIN BELOW ADVISORY LEVELS THERE AS WELL...WITH THE POSSIBLE EXCEPTION BEING OUR MOST WIND PRONE EASTERN ZONE LOCATIONS WHICH ALSO HAPPEN TO BE FAR ENOUGH AHEAD OF THE FRONT FOR STRONGER WINDS TO MIX DOWN DURING THE DAY...WE`LL HAVE TO KEEP AN EYE ON THAT. CLEARING FROM THE WEST TONIGHT...WIDESPREAD FREEZE WEST TO HARD FREEZE EAST TUESDAY MORNING AND WEDNESDAY MORNING BUT NOTHING UNUSUAL FOR LATE JANUARY. DRY CONDITIONS WITH TEMPERATURES JUMPING BACK ABOVE CLIMO THE SECOND HALF OF THE WEEK INTO THIS COMING WEEKEND...TO START FEBRUARY WITH RELATIVELY MILD CONDITIONS. && .AVIATION...BKN-OVC CLOUDS 5-8K FT AGL AND MTNS OBSCD THROUGH THIS AFTERNOON. ISOLD -SHRA EARLY THIS MORNING BECOMING SCT -SHRA AFTER 11Z MONDAY. SFC WINDS GENERALLY 8 TO 12 KTS THROUGH 14Z...THEN SWLY 10-20 KTS WITH HIGHER GUSTS EAST OF TUCSON THROUGH 00Z TUESDAY. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...NO FIRE WEATHER CONCERNS. SCATTERED SHOWERS AND BREEZY CONDITIONS TODAY. STRONGEST WINDS WILL BE FOR EASTERN COCHISE COUNTY WHERE GUSTS ABOVE 35 MPH ARE POSSIBLE. DRY WEATHER TUESDAY BUT WINDY ESPECIALLY IN THE UPPER GILA RIVER VALLEY. TEMPERATURES WILL BEGIN TO MODERATE WEDNESDAY WITH DRY CONDITIONS CONTINUING. && .TWC WATCHES/WARNINGS/ADVISORIES...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON M/M
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
850 PM EST TUE JAN 29 2013 .UPDATE (TONIGHT THROUGH WEDNESDAY)... 01Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A NOW HIGHLY AMPLIFIED UPPER LEVEL PATTERN IN PLACE ACROSS THE CONUS. MAIN FEATURE OF NOTE IS A SHARP AND DEEP TROUGH TRAVERSING THE CENTRAL PORTION OF THE COUNTRY AND FORCING A SIGNIFICANT SEVERE WEATHER OUTBREAK ACROSS THE CENTRAL AND LOWER MS VALLEY. IMPRESSIVE HEIGHT FALLS SPREADING EASTWARD HELPED TO AMPLIFY THE DOWNSTREAM RIDGE ALONG THE EASTERN SEABOARD DURING THE PAST 24 HOURS AND GAVE US YET ANOTHER UNSEASONABLY WARM DAY. IN FACT...IT WAS WARM ENOUGH TO FORCE A DECENT SEA-BREEZE CIRCULATION BY LATE TODAY...AND THIS FOCUS HAS ACTUALLY BEEN STRONG ENOUGH TO SUPPORT A FEW LIGHT SHOWERS ACROSS WESTERN MANATEE AND WESTERN HILLSBOROUGH COUNTIES THE PAST COUPLE HOURS (JANUARY?). AS WE COOL INTO THE LATE EVENING AND THE LOW LEVEL FOCUS RELAXES...THESE ISOLATED SHOWERS SHOULD END AND GENERALLY ANTICIPATE A DRY AND WARM OVERNIGHT PERIOD. STACKED RIDGING PATTERN WE HAVE ENJOYED FOR SEVERAL DAYS WILL QUICKLY EXIT DURING WEDNESDAY AS THE LARGE SCALE TROUGH AND ASSOCIATED HEIGHT FALLS SPREAD ACROSS THE SOUTHEAST CONUS. ASSOCIATED SURFACE COLD FRONT WILL ALSO BE PROGRESSING EASTWARD ACROSS THE GULF AND FL PANHANDLE THROUGH THE DAY. STILL APPEARS AS THOUGH THE BEST SYNOPTIC FORCING AND LOW LEVEL FOCUS FOR SHOWERS/ISOLATED STORMS WILL HOLD OFF UNTIL WEDNESDAY EVENING FOR THE NATURE COAST...AND MAINLY TOWARD OR AFTER MIDNIGHT FOR THE I-4 CORRIDOR SOUTHWARD. THEREFORE...FORECAST FOR WEDNESDAY WILL FEATURE MORE WARM TEMPERATURES AND ALSO INCREASING DEWPOINTS WITHIN A DEEP SOUTHERLY FLOW. AS MENTIONED ABOVE...WILL KEEP RAIN OUT OF THE FORECAST FOR THE DAYLIGHT HOURS...WITH THE EXCEPTION OF POTENTIALLY LEVY AND CITRUS COUNTIES WHERE INITIAL LEADING SHOWERS COULD START AS EARLY AS THE LATE AFTERNOON HOURS. AS THE HIGHER DEWPOINT AIR BEGINS TO MOVE NORTHWARD AHEAD OF THE FRONT...WILL NEED TO WATCH FOR THE POTENTIAL DEVELOPMENT OF SOME ADVECTION SEA-FOG LATE WEDNESDAY/WEDNESDAY EVENING. BEST CHANCES TO SEE THIS FOG DEVELOPMENT WOULD BE FROM TAMPA BAY NORTHWARD ALONG THE NATURE COAST WHERE SHELF WATERS ARE CURRENTLY COOLEST. && .AVIATION... SIMILAR TO LAST NIGHT...LOW CLOUDS AND MAYBE SOME FOG WILL DEVELOP BETWEEN 06-08Z. BEST CHANCES AT SEEING IFR CONDITIONS WILL BE LAL... TPA AND PIE. VFR AFTER 15Z BUT GUSTY SOUTHERLY WINDS POSSIBLY TO 30 KNOTS. && .MARINE... HIGH PRESSURE THAT HAS BEEN DOMINATING WATERS WILL BEGIN TO SLIDE AWAY TONIGHT AS A COLD FRONT MOVES INTO THE WESTERN GULF AND TRACKS EASTWARD...REACHING THE EAST GULF WED NIGHT/EARLY THU THEN SWEEPING OUT OF THE STATE DURING THU. HIGH PRESSURE BUILDS IN OVER THE GULF REGION FRI THEN MOVES EAST DURING THE WEEKEND. BOATING CONDITIONS BEGIN TO DETERIORATE TONIGHT AS WINDS INCREASE TO EXERCISE CAUTION SPEEDS LATER AND WILL HEADLINE THAT WITH THE AFTERNOON FORECAST. WINDS MOST LIKELY REACH SMALL CRAFT ADVISORY CRITERIA WED MORNING AND CONTINUE INTO FRI. THE ARRIVAL OF HIGHER DEWPOINT AIR BY LATE WEDNESDAY AFTERNOON/WED EVENING WILL LEAD TO SOME POTENTIAL DEVELOPMENT OF ADVECTION SEA-FOG. BEST CHANCES TO SEE THIS FOG DEVELOPMENT WOULD BE FROM TAMPA BAY NORTHWARD ALONG THE NATURE COAST WHERE SHELF WATERS ARE CURRENTLY COOLEST. THE WINDOW FOR ANY SEA-FOG IS BRIEF AS THE PASSAGE OF THE COLD FRONT WEDNESDAY NIGHT WILL END THIS POTENTIAL. && .PRELIMINARY POINT TEMPS/POPS... TPA 66 80 60 67 / 10 0 60 10 FMY 65 83 65 73 / 10 0 60 20 GIF 63 83 59 68 / 10 0 60 10 SRQ 65 78 62 68 / 10 0 60 10 BKV 63 82 57 65 / 10 10 60 10 SPG 66 77 61 67 / 10 0 60 10 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ UPDATE...MROCZKA AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
647 AM EST MON JAN 28 2013 .SYNOPSIS... HIGH PRESSURE WILL HOLD ACROSS THE AREA THROUGH TUESDAY. A STRONG COLD FRONT CROSS THE AREA LATE WEDNESDAY BRINGING SHOWERS AND POSSIBLE THUNDERSTORMS. COOL AND DRY HIGH PRESSURE WILL RETURN FOR THE END OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THIS MORNING...DEVELOPING IN-SITU WEDGE OVER AREA. LIGHT EAST TO NORTHEAST SURFACE WINDS. RUC SHOWS WEAK SHORT WAVE WHICH WILL TRAVERSE THE AREA DURING THE DAY. THIS COMBINED WITH WEAK ISENTROPIC LIFT AS SOUTHERLY WINDS ABOVE SURFACE BASED WEDGE BRING WARMER AIR ALOFT...THUS PROVIDING CONDITIONS FAVORABLE FOR WEAK ISENTROPIC LIFT. WILL KEEP THE SLIGHT CHANCE OF LIGHT RAIN THIS MORNING. BUT ISENTROPIC LIFT APPEARS TO BE STRONGER JUST TO THE WEST OF CAE...SO INCLUDED AN CHANCE AREA (30-40 PERCENT) OF LIGHT RAIN MAINLY DURING THE MORNING. TEMPERATURES IN THE UPPER 30S SHOULD RISE INTO THE 40S. THIS AFTERNOON...WEDGE WEAKENS. NOT SURE IT WILL COMPLETELY BREAK DOWN BUT SURFACE WINDS ARE EXPECTED TO BECOME MORE SOUTHERLY. WILL GRADUALLY DECREASE POPS TO ABOUT 10 PERCENT BY LATE AFTERNOON. WENT WITH HIGHS IN THE 50S WITH SORT OF A BLEND BETWEEN MODEL DATA AND THE MAX WEDGE TEMPERATURE TOOL. WITH MORE RAIN IN THE MORNING DECIDED TO LOWER HIGHS ABOUT 2 DEGREES...FROM UPPER 40S FAR NORTH THE UPPER 50S FAR SOUTH. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... WEDGE IS EXPECTED TO HAVE ERODED BY TONIGHT. IN THE ABSENCE OF ISENTROPIC LIFT...WILL GO WITH POPS 10 PERCENT OR LESS TONIGHT THROUGH EARLY TUESDAY NIGHT. LATER TUESDAY NIGHT...A WEATHER SYSTEM WITH AN APPROACHING COLD FRONT WILL BEGIN TO PULL MOISTURE TO THE REGION. WILL INCREASE POPS TO 20-30 PERCENT AFTER TUESDAY NIGHT AFTER MIDNIGHT. LOWS TONIGHT INT HE 40S. HIGHS TUESDAY IN THE LOWER TO MIDDLE 70S AND LOWS TUESDAY NIGHT UP IN THE UPPER 50S. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS THE HIGH BECOMES CENTERED OFFSHORE AND SOUTHERLY FLOW BRINGS WARM AIR TO REGION WEDNESDAY. A STRONG COLD FRONT WILL MOVE QUICKLY THROUGH THE REGION ON WEDNESDAY BRINGING PRECIPITATION TO THE AREA. HAVE INCLUDED THUNDER DUE TO THE STRONG DYNAMICS OF THE SYSTEM EVEN THOUGH INSTABILITY APPEARS LIMITED AT THIS TIME. THE CWA WILL BE IN THE RIGHT ENTRANCE REGION OF A LLJ AND UPPER LEVEL JET AND PWAT VALUES ARE RELATIVELY HIGH FOR THIS TIME OF YEAR. THE FRONTAL BOUNDARY WILL PROVIDE ADDITIONAL LIFT. THE JET SETUP AND TIGHT PRESSURE GRADIENT WILL CREATE BREEZY CONDITIONS ON WEDNESDAY. MODELS AGREE ON PRECIP BEING OUT OF THE AREA BY 06Z ON THURSDAY SO LOWERED POPS ACCORDINGLY. BY THURSDAY MORNING THE FRONT WILL BE OFF THE COAST AND HIGH PRESSURE CENTERED IN THE GULF WILL DOMINATE THE PATTERN. STRONG CAA ADVECTION BEHIND THE FRONTAL SYSTEM WILL RETURN MAX TEMPS TO THE MID TO UPPER 50S. LOW TEMPS WILL BE MUCH COOLER UNDER HIGH PRESSURE AND RADIATIONAL COOLING THROUGH THE END OF THE WEEK. FRIDAY THE ECMWF AND GFS SHOW A SHORTWAVE SHIFTING TOWARD THE EAST COAST FROM THE OHIO VALLEY BUT PRECIP REMAINS WELL NORTH OF THE AREA. COOL HIGH PRESSURE WILL BE CENTERED OVER THE SOUTHEAST ON SATURDAY. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... SATELLITE AND OBS INDICATE IFR/MVFR CONDITIONS ACROSS MUCH OF THE AREA THIS MORNING. THIS WAS EXPECTED...BUT CEILINGS HAVE BEEN LOWER THAN EXPECTED. RADAR LOOP ALSO SHOWS SOME ISENTROPIC LIFT INDUCED LIGHT RAIN DEVELOPING ACROSS THE CSRA AND SPREADING NORTHEAST THIS MORNING. INCREASING MOISTURE AND ISENTROPIC LIFT WILL OCCUR WITH LIGHT EAST/NORTHEAST WINDS AT THE SURFACE AND INCREASING SOUTHWEST WINDS ALOFT THIS MORNING. THIS WEDGE-TYPE PATTERN WILL CONTINUE THROUGH THE TAF PERIOD. MODELS TRY TO WEAKEN THE WEDGE ACROSS THE EASTERN CWA THIS AFTERNOON...BUT THEN TRIES TO SETTLE BACK TONIGHT. IFR/MVFR CONDITIONS WILL PERSIST FOR MUCH OF THE DAY. THE NAM INDICATES LLWS TOWARD MORNING...BUT BELOW THE CRITERIA FOR INCLUSION IN THE TERMINAL FORECASTS. CEILINGS ARE EXPECTED TO RISE SOME DURING THE LATE AFTERNOON...BUT CONDITIONS ARE EXPECTED TO ONCE AGAIN DETERIORATE DURING THE LATE EVENING/OVERNIGHT HOURS RETURNING TO MAINLY IFR CONDITIONS UNTIL THE END OF THE TAF PERIOD. EXTENDED AVIATION OUTLOOK... PERIODS OF IFR/MVFR CONDITIONS WILL OCCUR DURING TUESDAY MORNING BECAUSE OF HIGH LOW-LEVEL MOISTURE ASSOCIATED WITH THE SOUTHERLY FLOW WEST OF OFFSHORE HIGH PRESSURE. A COLD FRONT AND ASSOCIATED RESTRICTIONS...INCLUDING THUNDER...ARE POSSIBLE WEDNESDAY. STRONG AND GUSTY SOUTHERLY WINDS ARE EXPECTED WEDNESDAY AHEAD OF THE COLD FRONT. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
427 AM EST MON JAN 28 2013 .SYNOPSIS... HIGH PRESSURE WILL HOLD ACROSS THE AREA THROUGH TUESDAY. A STRONG COLD FRONT CROSS THE AREA LATE WEDNESDAY BRINGING SHOWERS AND POSSIBLE THUNDERSTORMS. COOL AND DRY HIGH PRESSURE WILL RETURN FOR THE END OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THIS MORNING...DEVELOPING IN-SITU WEDGE OVER AREA. LIGHT EAST TO NORTHEAST SURFACE WINDS. RUC SHOWS WEAK SHORT WAVE WHICH WILL TRAVERSE THE AREA DURING THE DAY. THIS COMBINED WITH WEAK ISENTROPIC LIFT AS SOUTHERLY WINDS ABOVE SURFACE BASED WEDGE BRING WARMER AIR ALOFT...THUS PROVIDING CONDITIONS FAVORABLE FOR WEAK ISENTROPIC LIFT. WILL KEEP THE SLIGHT CHANCE OF LIGHT RAIN THIS MORNING. EXPECT MORNING TEMPERATURES TO REMAIN IN THE 40S. THIS AFTERNOON...WEDGE WEAKENS. NOT SURE IT WILL COMPLETELY BREAK DOWN BUT SURFACE WINDS ARE EXPECTED TO BECOME MORE SOUTHERLY. WILL GRADUALLY DECREASE POPS TO ABOUT 10 PERCENT BY LATE AFTERNOON. WENT WITH HIGHS IN THE 50S WITH SORT OF A BLEND BETWEEN MODEL DATA AND THE MAX WEDGE TEMPERATURE TOOL. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... WEDGE IS EXPECTED TO HAVE ERODED BY TONIGHT. IN THE ABSENCE OF ISENTROPIC LIFT...WILL GO WITH POPS 10 PERCENT OR LESS TONIGHT THROUGH EARLY TUESDAY NIGHT. LATER TUESDAY NIGHT...A WEATHER SYSTEM WITH AN APPROACHING COLD FRONT WILL BEGIN TO PULL MOISTURE TO THE REGION. WILL INCREASE POPS TO 20-30 PERCENT AFTER TUESDAY NIGHT AFTER MIDNIGHT. LOWS TONIGHT INT HE 40S. HIGHS TUESDAY IN THE LOWER TO MIDDLE 70S AND LOWS TUESDAY NIGHT UP IN THE UPPER 50S. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS THE HIGH BECOMES CENTERED OFFSHORE AND SOUTHERLY FLOW BRINGS WARM AIR TO REGION WEDNESDAY. A STRONG COLD FRONT WILL MOVE QUICKLY THROUGH THE REGION ON WEDNESDAY BRINGING PRECIPITATION TO THE AREA. HAVE INCLUDED THUNDER DUE TO THE STRONG DYNAMICS OF THE SYSTEM EVEN THOUGH INSTABILITY APPEARS LIMITED AT THIS TIME. THE CWA WILL BE IN THE RIGHT ENTRANCE REGION OF A LLJ AND UPPER LEVEL JET AND PWAT VALUES ARE RELATIVELY HIGH FOR THIS TIME OF YEAR. THE FRONTAL BOUNDARY WILL PROVIDE ADDITIONAL LIFT. THE JET SETUP AND TIGHT PRESSURE GRADIENT WILL CREATE BREEZY CONDITIONS ON WEDNESDAY. MODELS AGREE ON PRECIP BEING OUT OF THE AREA BY 06Z ON THURSDAY SO LOWERED POPS ACCORDINGLY. BY THURSDAY MORNING THE FRONT WILL BE OFF THE COAST AND HIGH PRESSURE CENTERED IN THE GULF WILL DOMINATE THE PATTERN. STRONG CAA ADVECTION BEHIND THE FRONTAL SYSTEM WILL RETURN MAX TEMPS TO THE MID TO UPPER 50S. LOW TEMPS WILL BE MUCH COOLER UNDER HIGH PRESSURE AND RADIATIONAL COOLING THROUGH THE END OF THE WEEK. FRIDAY THE ECMWF AND GFS SHOW A SHORTWAVE SHIFTING TOWARD THE EAST COAST FROM THE OHIO VALLEY BUT PRECIP REMAINS WELL NORTH OF THE AREA. COOL HIGH PRESSURE WILL BE CENTERED OVER THE SOUTHEAST ON SATURDAY. && .AVIATION /09Z MONDAY THROUGH FRIDAY/... SATELLITE AND OBS INDICATE IFR/MVFR CONDITIONS ACROSS MUCH OF THE AREA THIS MORNING. THIS WAS EXPECTED...BUT CEILINGS HAVE BEEN LOWER THAN EXPECTED. INCREASING MOISTURE AND ISENTROPIC LIFT WILL OCCUR WITH LIGHT EAST/NORTHEAST WINDS AT THE SURFACE AND INCREASING SOUTHWEST WINDS ALOFT. THIS WEDGE-TYPE PATTERN SHOULD CONTINUE THROUGH THE TAF PERIOD. IFR/MVFR CONDITIONS WILL PERSIST FOR MUCH OF THE DAY. THE NAM INDICATES LLWS TOWARD MORNING...JUST BELOW THE CRITERIA FOR INCLUSION IN THE TERMINAL FORECASTS. CEILINGS ARE EXPECTED TO RISE SOME DURING THE LATE AFTERNOON...BUT CONDITIONS COULD ONCE AGAIN DETERIORATE TOWARD THE END OF THE TAF PERIOD RETURNING TO IFR/MVFR. EXTENDED AVIATION OUTLOOK... PERIODS OF MVFR OR LOWER CONDITIONS MAY OCCUR DURING THE REST OF MONDAY NIGHT INTO TUESDAY BECAUSE OF HIGH LOW-LEVEL MOISTURE ASSOCIATED WITH THE SOUTHERLY FLOW WEST OF OFFSHORE HIGH PRESSURE. A COLD FRONT AND ASSOCIATED RESTRICTIONS...INCLUDING THUNDER... ARE POSSIBLE WEDNESDAY. STRONG AND GUSTY SOUTHERLY WINDS ARE EXPECTED WEDNESDAY AHEAD OF THE COLD FRONT. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
151 AM EST MON JAN 28 2013 .SYNOPSIS... HIGH PRESSURE WILL HOLD ACROSS THE AREA THROUGH TUESDAY. A STRONG COLD FRONT CROSS THE AREA LATE WEDNESDAY BRINGING SHOWERS AND POSSIBLE THUNDERSTORMS. COOL AND DRY HIGH PRESSURE WILL RETURN FOR THE END OF THE WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... DEVELOPING IN-SITU WEDGE OVER AREA. WEAK ISENTROPIC LIFT TO THE NORTH HAS CAUSED SOME LIGHT RAIN TO DEVELOP AND MAY AFFECT NORTHERN COUNTIES OF LANCASTER AND CHESTERFIELD NEXT COUPLE OF HOURS. GENERALLY...MOST PRECIPITATION SHOULD REMAIN TO THE NORTH AS UPPER RIDGE AXIS MOVES EAST ACROSS THE REGION. EXPECT ONLY WEAK FORCING ABOVE WEDGE BUT RUC13 BRINGS WEAK SHORT WAVE THROUGH EARLY THIS MORNING TO COINCIDE WITH LIGHT RAIN TO THE NORTH. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... WEDGE IS PRESENTING A CHALLENGING FORECAST FOR MONDAY. RUC13 HAS A STRONGER BUT STILL WEAK SHORT WAVE RIDING ACROSS UPPER RIDGE BY THE AFTERNOON. WE HAVE A 20 PERCENT CHANCE OF LIGHT RAIN MUCH OF THE DAY. LOWERED HIGH TEMPERATURES ABOUT 2-3 DEGREES WITH CLOUD COVER AND EXPECTED WEDGE CONDITIONS. DID SORT OF A MODEL BLEND WITH WEDGE HIGH TEMPERATURE TOOL AND MODEL DATA. THIS GAVE HIGHS AROUND 50 FAR NORTH TO UPPER 50S FAR SOUTH. MONDAY NIGHT WILL NOT BE AS COLD AS WINDS BECOME SOUTH...LOWS WILL BE IN THE 40S. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... AS THE HIGH BECOMES CENTERED OFFSHORE AND FLOW BECOMES MORE SOUTHERLY TEMPS WILL WARM TUESDAY AND WEDNESDAY TO ABOVE NORMAL. CLOUD COVER WILL INCREASE TUESDAY AHEAD OF AN APPROACHING UPPER TROUGH. THE ASSOCIATED STRONG COLD FRONT WILL MOVE QUICKLY THROUGH THE REGION ON WEDNESDAY BRINGING PRECIPITATION TO THE AREA. HAVE INCLUDED THUNDER DUE TO THE STRONG DYNAMICS OF THE SYSTEM EVEN THOUGH INSTABILITY APPEARS LIMITED AT THIS TIME. THE CWA WILL BE IN THE RIGHT ENTRANCE REGION OF A LLJ AND UPPER LEVEL JET AND PWAT VALUES ARE RELATIVELY HIGH FOR THIS TIME OF YEAR. THE FRONTAL BOUNDARY WILL PROVIDE ADDITIONAL LIFT. THE JET SETUP AND TIGHT PRESSURE GRADIENT WILL CREATE BREEZY CONDITIONS ON WEDNESDAY. MODELS AGREE ON PRECIP BEING OUT OF THE AREA BY 06Z ON THURSDAY SO LOWERED POPS ACCORDINGLY. BY THURSDAY MORNING THE FRONT WILL BE OFF THE COAST AND HIGH PRESSURE CENTERED IN THE GULF WILL DOMINATE THE PATTERN. STRONG CAA ADVECTION BEHIND THE FRONTAL SYSTEM WILL RETURN MAX TEMPS TO THE MID TO UPPER 50S. LOW TEMPS WILL BE MUCH COOLER UNDER HIGH PRESSURE AND RADIATIONAL COOLING THROUGH THE END OF THE WEEK. FRIDAY THE ECMWF AND GFS SHOW A SHORTWAVE SHIFTING TOWARD THE EAST COAST FROM THE OHIO VALLEY BUT PRECIP REMAINS WELL NORTH OF THE AREA. COOL HIGH PRESSURE WILL BE CENTERED OVER THE SOUTHEAST ON SATURDAY. && .AVIATION /07Z MONDAY THROUGH FRIDAY/... EXPECT VFR CONDITIONS EARLY IN THE TAF PERIOD WITH MVFR CONDITIONS DEVELOPING TOWARD SUNRISE. INCREASING MOISTURE AND ISENTROPIC LIFT WILL OCCUR WITH LIGHT WINDS AT THE SURFACE AND INCREASING SOUTHWEST WINDS ALOFT. THIS WEDGE-TYPE PATTERN SHOULD CONTINUE THROUGH THE TAF PERIOD. VFR CONDITIONS SHOULD CONTINUE FOR MUCH OF TONIGHT BECAUSE OF THE INITIAL DRYNESS BUT EXPECT LOW CLOUDINESS WILL EVENTUALLY DEVELOP. FORECAST SOUNDINGS INDICATE MVFR OR POSSIBLY IFR CEILINGS DEVELOPING IN THE 09Z-12Z TIME FRAME. AN AVERAGE OF THE GFS AND NAM MOS SUPPORTS MVFR CEILINGS. BOUNDARY LAYER WINDS SUGGEST STRATUS IS FAVORED OVER FOG. THE NAM INDICATES LLWS JUST BELOW THE CRITERIA FOR INCLUSION IN THE TERMINAL FORECASTS. EXTENDED AVIATION OUTLOOK... PERIODS OF MVFR OR LOWER CONDITIONS MAY OCCUR DURING THE REST OF MONDAY NIGHT INTO TUESDAY BECAUSE OF HIGH LOW-LEVEL MOISTURE ASSOCIATED WITH THE SOUTHERLY FLOW WEST OF OFFSHORE HIGH PRESSURE. A COLD FRONT AND ASSOCIATED RESTRICTIONS...INCLUDING THUNDER...ARE POSSIBLE WEDNESDAY. STRONG AND GUSTY SOUTHERLY WINDS ARE EXPECTED WEDNESDAY AHEAD OF THE COLD FRONT. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
906 PM CST TUE JAN 29 2013 .DISCUSSION... ISSUED 905 PM CST TUE JAN 29 2013 INITIAL WIND SHIFT HAS PUSHED THROUGH ABOUT 3/4 OF THE CWA... CURRENTLY EXTENDING FROM ABOUT EFFINGHAM TO DANVILLE. TEMPERATURES STILL IN THE 60-65 RANGE AHEAD OF THIS AREA...WITH SOME GRADIENT WIND GUSTS OF 35-40 MPH. THE MAIN COLD FRONT WAS LOCATED JUST EAST OF THE IOWA BORDER...WHERE TEMPERATURES FALL INTO THE 30S. HAVE HAD SOME WAVES OF LOW PRESSURE RIDING ALONG THE FRONT...WHICH HAS SLOWED DOWN ITS PASSAGE SOMEWHAT...BUT LATEST MODEL GUIDANCE STILL INDICATES IT SHOULD START MOVING THROUGH THE WESTERN CWA LATE TONIGHT. MAIN CONCERN REMAINS WITH THE RAIN TONIGHT AND THE FLOOD WATCH. EVENING UPPER AIR SOUNDING FROM LINCOLN HAD PRECIPITABLE WATER VALUES OF 1.43 INCHES...WHICH LOCAL RESEARCH INDICATES IS A RECORD FOR JANUARY IN THIS AREA. SO FAR...HAVE SEEN LITTLE OR NO RAIN IN THE FAR SOUTHEAST CWA...BUT THAT SHOULD BE INCREASING SHORTLY AS A NARROW CONVECTIVE LINE FROM SALEM SOUTHWEST INTO MISSOURI MOVES QUICKLY EASTWARD. RAP MODEL SHOWS THE SAME HIGH PWAT VALUES AFFECTING SOUTHEAST ILLINOIS OVER THE NEXT SEVERAL HOURS...SO SOME HEAVY RAIN THERE IS STILL LIKELY. THE WESTERN HALF OF THE CWA HAS SEEN AMOUNTS OVER AN INCH COMMON WEST OF A BLOOMINGTON TO JACKSONVILLE LINE...WITH SOME 1.5 TO 2 INCH TOTALS TOWARD THE ILLINOIS RIVER VALLEY. HAVE KEPT THE FLOOD WATCH IN PLACE FOR NOW OVER THE ENTIRE AREA...BUT HAVE SOME CONCERNS ABOUT THE NORTHWEST CWA...AS REGIONAL RADAR MOSAICS SHOW THE HEAVIEST AXIS OF RAIN FURTHER TO THE EAST. WILL WATCH THIS FOR A COUPLE MORE HOURS BEFORE DECIDING WHETHER OR NOT TO TRIM DOWN THE WATCH AREA. UPDATED ZONES/GRIDS HAVE BEEN SENT. GEELHART && .AVIATION... ISSUED 545 PM CST TUE JAN 29 2013 NARROW LINE OF THUNDERSTORMS EXPECTED TO MOVE INTO KBMI/KDEC OVER THE NEXT HOUR OR SO...AND REACH KCMI AROUND 0230Z. HAVE SEEN SOME GUSTS OF 30-40 KNOTS WITH THE LINE...WITH WINDS TRENDING TO THE NORTHWEST IN THE LARGER RAIN SHIELD THAT EXTENDS FURTHER WEST. CEILINGS HAVE RISEN INTO THE VFR RANGE IN A NARROW AREA BEHIND THE LINE TO NEAR THE MISSISSIPPI RIVER...BUT ARE EXPECTED TO DROP BACK DOWN TO IFR LEVELS LATER THIS EVENING. A PERIOD OF MORE SHOWERY PRECIPITATION IS EXPECTED BETWEEN MIDNIGHT AND 12Z WORKING ITS WAY WEST TO EAST. HOWEVER...ANOTHER AREA OF PRECIPITATION WILL SET UP OVER MISSOURI/IOWA LATE IN THE NIGHT AND LIFT NORTHEAST. FORECAST SOUNDINGS SHOWING RAIN SWITCHING TO SNOW WEDNESDAY...WITH SOME POTENTIAL FOR SLEET FOR AN HOUR OR TWO AROUND KSPI/KDEC. NORTHWEST WINDS EXPECTED TO RAMP UP WEDNESDAY MORNING AND GUST FROM 25-30 KNOTS OR SO FROM LATE MORNING THROUGH MUCH OF THE AFTERNOON. GEELHART && .PREV DISCUSSION... ISSUED 320 PM CST TUE JAN 29 2013 MAIN CONCERN THIS FORECAST PACKAGE CONTINUES TO INVOLVE THE POTENTIAL HEAVY RAIN/FLOOD WATCH EVENT FOR TONIGHT...WHEN RAIN WILL CHANGE OVER TO SNOW...AND FALLING TEMPS IN THE SHORT TERM. ALL MODELS IN GOOD AGREEMENT WITH OVERALL UPPER LEVEL PATTERN THROUGH THE SHORT TERM...AND WITH THE SFC FEATURES AND MOVEMENTS THROUGH FRIDAY. EXTENDED MODELS HAVE TRENDED INTO BETTER AGREEMENT IN THE EXTENDED WITH SFC FEATURES AS WELL. THEREFORE CONFIDENCE IS ABOVE AVERAGE FOR THIS FORECAST PACKAGE. SHORT TERM...TONIGHT THROUGH FRIDAY A SFC LOW IN CENTRAL OKLAHOMA IS FORECAST TO CONTINUE TO MOVE NORTHEAST ALONG A FRONTAL SYSTEM STRETCHING FROM WI...THROUGH NORTHWESTERN IL...THROUGH MO AND INTO OK. THIS LOW WILL MOVE ACROSS CENTRAL ILLINOIS THIS EVENING AND INTO SOUTHERN MICH JUST AFTER MIDNIGHT. THE UPPER LEVEL TROUGH ASSOCIATED WITH THIS SFC SYSTEM WILL REMAIN BACK IN THE CENTRAL US AND NOT MOVE INTO AND THROUGH THE CWA UNTIL TOMORROW EVENING. THE TROUGH MOVES THROUGH...BUT THEN BROADENS AS ANOTHER SMALLER AND LESS INTENSE SFC LOW MOVES OUT OF THE PLAINS AND THROUGH SOUTHERN IL THURSDAY. THIS WILL PUSH THROUGH QUICKLY AND THEN COLD HIGH PRSS MOVES BACK INTO THE AREA FOR THUR NIGHT AND FRIDAY. SHOWERS AND THUNDERSTORMS WITH HEAVY RAINFALL ARE FORECAST TO CONTINUE TO MOVE ACROSS THE CWA TONIGHT. STORMS WILL BE MOVING VERY QUICKLY TO THE NORTHEAST THIS EVENING AND COULD BE SEVERE AT TIMES WITH DAMAGING WINDS. TORNADO WATCHES ARE ONGOING TO THE SOUTHWEST OF THE AREA...AND OUR CWA MAY HAVE TO BE INCLUDED LATER THIS AFTERNOON AND INTO THIS EVENING IF THE STORMS SOUTHWEST OF THE AREA MAINTAIN THEIR STRENGTH AS THEY MOVE NORTHEAST. TOMORROW...THE PCPN WILL BEGIN TO CHANGE TO ALL SNOW AS MUCH COLDER AIR ADVECTS INTO THE AREA. MODELS ARE FORECASTING AN AREA OF DEFORMATION SNOW TO SETUP WEST OF THE TRACK OF THE SFC LOW TOMORROW WITH THE HIGHEST ACCUMULATING SNOW STAYING NORTHWEST OF THE IL RIVER. LOOKING FOR ABOUT AN INCH ALONG A RUSHVILLE TO BLOOMINGTON LINE WITH UP TO AROUND 1.5 INCHES AROUND GALESBURG. AMOUNTS OF A HALF AN INCH OR LESS WILL BE ALONG I-72. AS THIS SYSTEM PULLS EAST AND NORTHEAST...A SLIGHT CHANCE OF SNOW WILL CONTINUE ACROSS THE EXTREME NORTHEAST OF THE CWA WED NIGHT. WITH THE TROUGH BROADENING...A SFC LOW WILL MOVE OUT OF THE PLAINS AND THROUGH SOUTHERN IL THURSDAY. THIS WILL BRING A SLIGHT CHANCE OF MORE SNOW TO THE WHOLE CWA...MAINLY THUR AFTERNOON. BEYOND THIS...COLD ARCTIC HIGH PRSS WILL DROP INTO THE REGION WITH DRY AND VERY COLD WEATHER FOR THUR NIGHT AND FRIDAY. LOWS TONIGHT WILL BE CLOSE TO MIDNIGHT AND HIGHS TOMORROW WILL PROBABLY BE JUST AFTER MIDNIGHT TONIGHT. TEMPS WILL THEN GRADUALLY FALL TOMORROW THROUGH TOMORROW NIGHT. THEN COLDER AIR WILL ADVECT INTO THE REGION FOR THUR NIGHT AND FRIDAY...WITH TEMPS AROUND ZERO IN THE NORTHWEST TO IN THE LOWER TEENS IN THE SOUTHEAST...FOR THUR NIGHT. FRI TEMPS WILL BE WELL BELOW NORMAL FOR FRIDAY AS WELL...NOT REACHING ABOVE FREEZING ANYWHERE IN THE CWA. LONG TERM...FRIDAY NIGHT THROUGH TUESDAY MODELS HAVE ANOTHER SFC LOW DROPPING ACROSS NORTHERN IL FRIDAY NIGHT...SPREADING SOME LIGHT SNOW ACROSS THE NORTHEASTERN HALF OF THE CWA. THIS CLIPPER SYSTEM WILL BE QUICK SO ACCUMULATIONS WILL BE VERY LIGHT. BEYOND THIS...ANOTHER WEAK SYSTEM IS FORECAST TO MOVE ACROSS THE AREA WITH LIGHT PCPN MON AND MONDAY NIGHT. FOR NOW WILL KEEP ONLY SLIGHT CHC OF POPS IN THE FORECAST...WHICH WILL NOT BE MENTIONED IN THE WORDED FORECAST. OTHER THAN THESE TWO SYSTEMS...REMAINDER OF THE LONG TERM PERIODS WILL BE DRY. TEMPS WILL START COLD BUT THEN WARM QUICKLY FOR THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. WARMEST DAY LOOKS TO BE MONDAY WITH TEMPS 5+ DEGREES ABOVE NORMAL. AUTEN && .ILX WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH UNTIL 6 AM CST WEDNESDAY FOR ILZ027>031-036>038- 040>057-061>063-066>068-071>073. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
902 PM CST TUE JAN 29 2013 .MESOSCALE DISCUSSION... 240 PM CST THE THREAT FOR HEAVY RAIN DEVELOPING AND POSSIBLY A COUPLE SEVERE STORMS CONTINUES. THE LATEST HAND ANALYSIS PLACES THE COLD FRONT JUST PAST THE MISSISSIPPI RIVER IN NORTHWEST IL WITH A SUBTLE PRE-FRONTAL TROUGH FROM JUST EAST OF ROCKFORD SOUTH TOWARD PEORIA. THIS PRE- FRONTAL TROUGH DOES HAVE AN INSTABILITY PLUME AIDED BY LOW TO MID 60S TEMPERATURES...AND LOW-LEVEL CAPE IS ANALYZED NEAR 100 J/KG WITH AROUND 300-500 J/KG OF SURFACE-BASED CAPE. THIS INSTABILITY THOUGH IS NOT LINING UP WITH ANY GREAT STORM ACTIVITY. SATELLITE AND RADAR TRENDS SHOW THAT A LARGE SWATH OF RAIN HAS EXPANDED FROM MO NORTHEAST THROUGH WESTERN IL AND SOUTHERN WI...STABILIZING MUCH OF THAT AREA. AT THE FRONT EDGE OF THIS...NEAR THE PRE-FRONTAL TROUGH...MORE CONVECTIVE-LIKE SHOWERS ARE PRESENT. THAT CONVECTION ON THE ILX RADAR HAS STRUGGLED TO BECOME WELL-DEFINED AND HAS MORE OF A QUASI-LINEAR MUSHY LOOK RIGHT NOW. LIGHTNING HAS BEEN SOMEWHAT SPORADIC AND REALLY HAS ONLY BEEN SEEN IN THE CLUSTER THAT IS NEARING CHICAGO...POSSIBLY ASSOCIATED WITH A WARM AIR ADVECTION FLANK AHEAD OF THE SYSTEM. OVERALL THE TREND HAS BEEN SLIGHTLY DOWN WITH NO LOCAL STORMS APPROACHING SEVERE LIMITS...AND A FEW 30-37 KT GUSTS OBSERVED. AT THIS TIME...IT REMAINS QUITE MARGINAL FOR SEVERE WEATHER AND MAY CONTINUE TO THROUGH MUCH OF THE AFTERNOON AS NO IMMEDIATE STRONG IMPULSES UPSTREAM ARE EVIDENT. TOWARD SUNSET AND INTO THIS EVENING...AREAS ALONG AND EAST OF I-55 WILL REMAIN FAVORED FOR STORM ACTIVITY ON THE NOSE OF AN INCREASING LOW LEVEL JET AND JUST MORE IMPROVED OVERALL FORCING. EXPLICIT CONVECTIVE MODELS AGREE THIS AREA WILL BE UNDER SOME STRONGER ACTIVITY THIS EVENING...BUT WHETHER THAT IS TO THE LIMITS TO FLIRT WITH SEVERE IS LOW CONFIDENCE. THE FORECAST DCAPE DOES INCREASE TO AROUND 400-500 J/KG ON THE NAM AND THE LOW-LEVEL SHEAR/HELICITY REMAINS HIGH IN THE STRONG ATMOSPHERIC WINDS. THIS MAY END UP BEING OUR BEST...ALBEIT NARROW WINDOW FOR SEVERE WEATHER. HEAVY RAIN REMAINS THE PRIMARY POTENTIAL HAZARD. WHILE IT IS A QUASI- LINEAR MUSHY LOOK RIGHT NOW...RAINFALL RATES ARE LIKELY VERY EFFICIENT IN ANY ACTIVITY AND WILL CONTINUE AS SUCH LATE THIS AFTERNOON INTO TONIGHT. A PERSISTENT FOCUS IS SEEN IN THE RAP AND NAM FORECASTS AS DEEP LAYER MOISTURE CONVERGENCE FURTHER INCREASES TONIGHT AS THE UPPER TROUGH INCHES EASTWARD. WIDESPREAD RAINFALL AMOUNTS OF ONE TO TWO AND A HALF INCHES LOOK LIKELY...WITH POTENTIALLY THE HIGHER END AMOUNTS BEING WIDESPREAD. WITH MUCH OF THIS GOING TOWARD RUNOFF...AT LEAST LOCALIZED PONDING TO POSSIBLE FLOODING WILL BE LIKELY. MTF && .DISCUSSION... 318 PM CST SHORT TERM...REST OF TODAY THROUGH WEDNESDAY NIGHT... FOR HEADLINES...KEPT FLOOD WATCH AS IS AND NO WINTER HEADLINES ARE EXPECTED AT THIS TIME. A DEEP TROUGH LIES ACROSS THE WESTERN US WITH ITS AXIS OVER THE GREAT PLAINS...WHILE A SURFACE LOW IS OVER ONTARIO. THE SURFACE LOWS COLD FRONT EXTENDS FROM THE LOW THROUGH CENTRAL WI TO ALONG THE MISSISSIPPI RIVER...AND IT IS SLOWLY MAKING ITS WAY INTO WESTERN IL. THE TEMPERATURE GRADIENT ACROSS THE FRONT IS RATHER IMPRESSIVE WITH 60 DEGREES IN PERU IL AND 38 DEGREES IN OTTUMWA IA...WITH JUST 176 MILES BETWEEN THE TWO CITIES. SHOWERS AND THUNDERSTORMS HAVE SPREAD INTO NORTHERN IL AHEAD OF THE COLD FRONT AND WILL CONTINUE TO SPREAD ACROSS THE CWA THIS AFTERNOON/EARLY EVENING. INDIVIDUAL CELLS HAVE BEEN CLOCKED AT 50-60 KT MOVING FROM THE SOUTHWEST TO THE NORTHEAST. SEVERE STORMS ARE STILL POSSIBLE THIS AFTERNOON...FOR MORE INFORMATION ON THE SEVERE WEATHER OUTLOOK AND RELATED PARAMETERS PLEASE SEE THE MESOSCALE DISCUSSION ABOVE. PWAT VALUES WILL BE IN EXCESS OF 1-1.5 INCHES THIS AFTERNOON/EVENING WITH DEWPOINTS CURRENTLY IN THE UPPER 50S TO LOW 60S FALLING OVERNIGHT. FLOW THROUGHOUT THE ATMOSPHERIC COLUMN IS ROUGHLY PARALLEL TO THE FRONT WHICH WILL INHIBIT THE FRONT FROM RAPIDLY PROGRESSING THROUGH THE CWA. TRAINING WILL ALSO BECOME AN ISSUE ALONG THE FRONT ALLOWING FOR IMPRESSIVE RAIN TOTALS. THE UPPER LEVEL JET STRETCHES FROM TEXAS THROUGH MINNESOTA BEFORE CURVING TOWARD QUEBEC. THE RIGHT JET ENTRANCE REGION LIES OVER SOUTHWEST WI/NORTHWEST IL ALMOST COLLOCATED WITH THE FRONT WHICH WILL CONTINUE TO SUPPORT THUNDERSTORM AND SHOWER FORMATION. BASED ON WHAT HAS PASSED OVER THE OFFICE THIS AFTERNOON...SOME OF THESE SHOWERS/STORMS WILL PRODUCE BRIEF INTENSE DOWNPOURS. THE JET AND FRONT CONTINUE ACROSS THE CWA TONIGHT WITH THE SOUTHERN JET STREAKS LEFT EXIT REGION POSSIBLY COUPLING WITH THE FRONT. AS SUCH EXPECTING PERIODS OF HEAVY RAIN TO CONTINUE OVERNIGHT. WHEN ALL IS SAID AND DONE...THINKING 1.5-2.5 INCHES OF RAIN ARE POSSIBLE ACROSS THE AREA. LOCALLY HIGHER AMOUNTS ARE CERTAINLY POSSIBLE. QUICKLY CHECKING THE OFFICES SOIL TEMPS...2 AND 4 INCHES BELOW THE SURFACE ARE ABOVE FREEZING AT 35 DEGREES WHILE 8 INCHES IS STILL FROZEN AT 27 DEGREES. AS SUCH EXPECTING PONDING OF WATER IN THE TYPICAL LOW LYING SPOTS...SINCE THE SOIL WILL NOT BE ABLE TO TAKE IN AS MUCH WATER AS USUAL. THEREFORE MADE NO ADJUSTMENTS TO THE FLOOD WATCH. TEMPS WILL BEGIN TO FALL OVERNIGHT WITH LOWS IN THE LOW 30S NEAR RFD TO ARND 50 NEAR RENSSELAER. WEDNESDAY... TEMPS WILL CONTINUE TO FALL WEDNESDAY MORNING WITH PRECIP TRANSITIONING TO SNOW AS A SWATH OF MOISTURE ASSOCIATED WITH THE 700 MB LOW SURGES NORTH. SOUNDINGS INDICATE A BRIEF PERIOD OF SLEET IS POSSIBLE DURING THE TRANSITION BUT NOT EXPECTING ANY SIGNIFICANT SLEET ACCUMULATION. EXPECTING AREAS AROUND RFD TO CHANGE OVER TO SNOW BEFORE 8AM...CHICAGO AROUND 3PM...AND NW INDIANA 4-6PM. FOR SNOW TOTALS...EXPECTING THE HIGHEST TOTALS IN FAR NW IL IN WINNEBAGO AND OGLE COUNTIES. THE NAM IS MUCH MORE EXCITED THAN THE GFS ABOUT THE SNOW POTENTIAL BUT BOTH MODELS SHOW THE SAME SET UP THAT IS FAVORABLE FOR MESOSCALE SNOW BANDS. 850-700 MB FRONTOGENESIS MOVES OVER NW IL/E IA EARLY WEDNESDAY MORNING WITH EPV VALUES BELOW 0 JUST ABOVE IT...INDICATING LOCALIZED INTENSE FORCING AND SYMMETRIC INSTABILITY. HOWEVER EXPECTING TEMPS TO BE ABOVE FREEZING AT THIS POINT. THE FRONTOGENESIS AND INSTABILITY SHIFT EASTWARD THROUGH THE MORNING AND THEN WEAKEN AFTER NOON. THE LEFT JET EXIT REGION OF THE UPPER LEVEL JET WILL ALSO BE OVER NORTHERN IL THROUGH WEDNESDAY AFTERNOON SO SYNOPTIC-SCALE LIFT SHOULD NOT BE AN ISSUE. WHILE MESOSCALE BANDS OF RAIN OR SNOW ARE VERY LIKELY TOMORROW...THESE FEATURES ARE HARD TO PINPOINT EVEN THIS FAR OUT. THEREFORE WENT WITH 3-5 INCHES OF SNOW OVER WINNEBAGO AND OGLE COUNTIES TOMORROW...BUT THIS NUMBER COULD EASILY BE HIGHER IF A BAND OF SNOW SETS UP. THE BIG QUESTIONS ARE WILL THE BEST FORCING ALIGN WITH SNOW OR RAIN...HOW LONG WILL THE FORCING LAST...AND WHERE WILL THE MESOSCALE BAND SET UP. AS MENTIONED BEFORE...THE FRONTOGENESIS WEAKENS AND STABILITY INCREASES IN THE AFTERNOON AS THE SNOW SPREADS ACROSS THE REST OF THE CWA. SO INTENSE MESOSCALE BANDS ARE NOT AS LIKELY...BUT FORCING FROM THE UPPER LEVEL JET STILL LOOKS FAVORABLE FOR A LITTLE SNOW. AS SUCH EXPECTING 1 TO 3 INCHES OF SNOW ACROSS BOONE AND MCHENRY COUNTIES...AND THEN AN INCH OR LESS EVERYWHERE ELSE. SNOW ENDS FROM WEST TO EAST...WITH NO SNOW EXPECTED AFTER MIDNIGHT ON WEDNESDAY. TEMPS CONTINUE TO TUMBLE TO THE TEENS OR SINGLE DIGITS WEDNESDAY NIGHT. WINDS 20-25 MPH WITH GUSTS UP TO 30 MPH SLOWLY WEAKEN OVERNIGHT...BUT EXPECTING WINDCHILLS TO BE BTWN 1 AND -10. JEE EXTENDED PERIOD...THURSDAY THROUGH TUESDAY... MAIN FORECAST CONCERN IN EXTENDED PERIOD DEALS WITH REINFORCEMENT OF ARCTIC COLD THURSDAY NIGHT/FRIDAY...AND THE POTENTIAL FOR LIGHT SNOW FRIDAY NIGHT/SATURDAY WITH A COUPLE CLIPPER-TYPE SYSTEMS ON THE BACK SIDE OF THE RETREATING LOW LEVEL COLD AIR. MEDIUM RANGE GUIDANCE APPEARS TO BE IN GOOD AGREEMENT AT THE START OF THE PERIOD THURSDAY MORNING...WITH DEEP SURFACE LOW LIFTING NORTHEAST ACROSS EASTERN QUEBEC AND DEEP UPPER LEVEL TROUGH ACROSS MUCH OF EASTERN NORTH AMERICA. ALL OF THE GLOBAL MODELS DEPICT ANOTHER STRONG SHORT WAVE DIGGING SOUTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES REGION THROUGH THE DAY... ACCOMPANIED BY A STRONG PUSH OF COLD ARCTIC AIR WITH 850 MB TEMPS OF -22 TO -24 C MOVING INTO THE CWA BY THURSDAY EVENING. MODEL SOUNDINGS AND TIME/HEIGHT SERIES INDICATE DRY MID/UPPER LEVELS AHEAD OF THIS DIGGING SHORT WAVE...WITH MODEL GENERATED QPF LIMITED TO THE MID/LOWER MISSOURI RIVER VALLEY INTO THE LOWER OHIO VALLEY THURSDAY AFTERNOON AND EVENING...THE COMBINATION OF DIGGING VORT...COLD ADVECTION WITH VERY COLD ARCTIC AIR...AND RELATIVELY MOIST LOW LEVELS ALL POINT TO THE POTENTIAL FOR AT LEAST SOME FLURRIES ACROSS THE FORECAST AREA THURSDAY AFTERNOON/EVENING. TEMPS...WHICH SHOULD ONLY TOP OUT IN THE MID TEENS NORTH AND LOWER 20S SOUTH AFTER WEDNESDAYS COLD FRONT...SHOULD EASILY FALL TO AROUND/BELOW ZERO ACROSS NORTH CENTRAL IL BY SUNRISE FRIDAY AND TO PERHAPS THE LOW POSITIVE SINGLE DIGITS ACROSS THE SOUTH WITH STRONG LOW LEVEL COLD ADVECTION THURSDAY NIGHT. HAVE TRENDED COLDER TOWARD THE 00Z GEFS MOS...AND A FEW DEGREES BELOW THAT AROUND ROCKFORD. THIS MAY NOT BE COLD ENOUGH ESPECIALLY IF SIGNIFICANT SNOW PACK IS IN PLACE AFTER WEDNESDAY. WINDS SHOULD REMAIN BLUSTERY ESPECIALLY IN THE EVENING WITH THE ENHANCED GRADIENT TO THE EAST OF THE CANADIAN HIGH BUILDING SOUTHEAST THROUGH THE PLAINS...SUPPORTING WIND CHILLS -10 TO -20 F OVERNIGHT. THE MID-LEVEL SHORT WAVE TROUGH AXIS IS PROGGED TO MOVE OFF TO THE SOUTHEAST OF THE FORECAST AREA EARLY FRIDAY MORNING...WITH FAIRLY STRONG HEIGHT RISES DEVELOPING IN ITS WAKE. COLD SURFACE HIGH PRESSURE CENTER WILL CONTINUE TO PUSH SOUTHEAST THROUGH THE LOWER OHIO VALLEY INTO TENNESSEE BY EVENING. CORE OF THE COLDEST AIR WILL SHIFT OFF TO THE EAST/SOUTHEAST BY AFTERNOON...THOUGH COLD MORNING START AND SHALLOW MIXED LAYER BENEATH SUBSIDENCE INVERSION WILL ALLOW ONLY MARGINAL MODERATION OF TEMPS AT THE SURFACE. HAVE ALSO TRENDED COLDER WITH MAXES FRIDAY TOWARD COLDER GFS/GEFS MOS NUMBERS. NORTHERN EXTENT OF SURFACE RIDGE AXIS MOVES ACROSS THE CWA FRIDAY EVENING...WITH WARM ADVECTION ALREADY DEVELOPING ON THE WESTERN PERIPHERY OF THE RETREATING LOW LEVEL COLD AIR DOME. WITH NORTHWEST FLOW ALOFT ON THE BACK SIDE OF THE DEPARTING LONG-WAVE UPPER TROUGH THIS SETS THE STAGE FOR A COUPLE OF MODEST SHORT WAVES TO BRING A COUPLE POTENTIAL PERIODS OF LIGHT SNOW TO THE REGION FRIDAY NIGHT AND SATURDAY. ECMWF/GFS 12Z RUNS REMAIN IN FAIRLY GOOD AGREEMENT IN DEVELOPING LIGHT QPF ACROSS THE AREA WITH A WEAK SURFACE LOW MOVING ACROSS NORTHERN ILLINOIS SATURDAY. UPPER JET CORE THEN SHIFTS SLOWLY EAST/NORTHEAST ACROSS THE NORTHERN/CENTRAL GREAT LAKES SATURDAY NIGHT...AS HIGH PRESSURE RIDGE MOVES ACROSS THE REGION THROUGH SUNDAY. WITH COLD CORE OF UPPER TROUGH OFF TO THE EAST...TEMPS MODERATE BACK TO MORE SEASONABLE LEVELS SATURDAY (MID-UPPER 20S) AND PERHAPS A BIT ABOVE (30S) SUNDAY AS WINDS SHIFT SOUTH IN THE AFTERNOON WEST OF THE RIDGE AXIS. MODERATION LOOKS TO CONTINUE MONDAY AS ECMWF/GFS REMAIN IN GOOD AGREEMENT IN TAKING AN AREA OF SURFACE LOW PRESSURE NORTH OF THE CWA ACROSS MN/WI. DRY HIGH PRESSURE BLOCKS MOISTURE RETURN FROM THE SOUTH FOR THE MOST PART... WITH NEXT CHANCE OF ORGANIZED PRECIP OCCURRING WITH THE COLD FRONT ASSOCIATED WITH THIS LOW MONDAY/MONDAY NIGHT...AND MAINLY ACROSS THE SOUTHEASTERN CWA. GEM MEANWHILE DURING THIS PERIOD BECOMES A COLD OUTLIER...WITH CONSISTENT ECMWF/GFS SOLUTIONS FAVORED AT THIS DISTANCE. THIS WOULD INDICATE COOLER/SEASONAL TEMPS RETURN TUESDAY. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 03Z... * PERSISTENT LIGHT TO OCCASIONALLY MODERATE RAIN THROUGH LATE TOMORROW MORNING. * PREVAILING IFR CIGS/VIS FROM LATE EVENING THROUGH EARLY TOMORROW AFTERNOON. * WIND SHIFT TO NLY-NNELY ARND 04Z THEN BCCKING TO NWLY TOMORROW MORNING. KREIN //DISCUSSION...UPDATED 00Z... THE LINE OF HEAVIEST RAIN AND SCATTERED THUNDERSTORMS HAS PUSHED EAST OF ALL TERMINALS EXCEPT GYY...WHICH WILL BE IMPACTED SHORTHLY. WHILE THE HEAVIEST RAIN AND THUNDERSTORM POTENTIAL IS ALONG THIS LINE...THERE IS STILL A SMALL LINGERING CHANCE OF SOME ISOLATED THUNDER FOR A SHORT TIME FOLLOWING THE PASSAGE OF THIS LINE. FOR THE REMAINDER OF THE EVENING AND OVERNIGHT...WIDESPREAD RAIN AND IFR CIGS WILL COVER THE AREA AND IMPACT ALL TERMINALS. WINDS WILL SHIFT TO NLY-NNELY EARLY THIS EVENING FOLLOWING THE PASSAGE OF THE COLD FRONT...BUT IT WILL BE QUITE SOME TIME UNTIL THE COOLER...DRIER AIR FILTERS OVER THE REGION. RAIN SHOULD BEGIN TO TAPER OFF TOMORROW MORNING AND TRANSITION OVER TO LIGHT SNOW BY EARLY AFTERNOON. THE IFR CIGS WILL PERSIST UNTIL THE DRIER AIR ASSOCIATED WITH THE COOLER AIRMASS OVERSPREADS THE REGION. SO...BY EARLY TOMORROW AFTERNOON...EXPECT THE BIGGEST IMPROVEMENT TO FLIGHT CONDITIONS...IMPROVING TO MVFR...BUT AT THAT POINT...LIGHT SNOW SHOULD BEGIN WITH SOME ACCUMULATION POSSIBLE. KREIN //ORD AND MDW CONFIDENCE...UPDATED 03Z... * HIGH CONFIDENCE IN PCPN TRENDS. * MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS. * MEDIUM TO HIGH CONFIDENCE IN CIG/VIS TRENDS...BUT LOWER CONFIDENCE IN EXACT TIMING OF IMPROVEMENT. KREIN //OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z... THURSDAY...CHANCE OF FLURRIES IN THE AFTERNOON/EVENING. MVFR CIGS POSSIBLE. WEST WINDS GUSTING TO 25-30KT. FRIDAY...VFR EARLY. CHANCE OF SNOW WITH MVFR CIGS/VIS OVERNIGHT. SATURDAY...CHANCE OF SNOW WITH MVFR CIGS/VIS EARLY...THE VFR OVERNIGHT. SUNDAY...VFR. WX NIL. MONDAY...SLIGHT CHANCE RAIN/SNOW. MVFR CIGS/VIS POSSIBLE. KREIN && .MARINE... 1248 PM CST SEVERAL WAVES OF LOW PRESSURE WILL RIDE UP A SLOW MOVING COLD FRONT TONIGHT THROUGH WEDNESDAY AFTERNOON...AS THE FRONT TRAVERSES LAKE MICHIGAN. STRONG SOUTH TO SOUTHWEST WINDS AHEAD OF THE FRONT HAVE PROMPTED A SMALL CRAFT ADVISORY FOR THE IL AND IN NEARSHORE. WINDS WILL SUBSIDE AS THE FRONT APPROACHES THE ILLINOIS WATERS LATE THIS AFTERNOON...AND THE INDIANA WATERS THIS EVENING. AREAS OF DENSE FOG ARE POSSIBLE INTO THIS EVENING...MAINLY OVER THE SOUTH HALF OF THE LAKE...AS UNSEASONABLY MILD AND HUMID AIR MOVES OVER THE CHILLY WATER. BEHIND THE COLD FRONT...NORTHWEST WINDS WILL RAMP UP AS THE FINAL WAVE OF LOW PRESSURE MOVES INTO EASTERN CANADA AND INTENSIFIES...WHILE STRONG HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS. GALE FORCE WINDS WILL DEVELOP BY MID MORNING WEDNESDAY AND SLOWLY DIMINISH BELOW GALE FORCE THURSDAY MORNING. THE GALE WATCH WILL BE UPGRADED TO A GALE WARNING WITH THE 300 PM GLFLM ISSUANCE. STRONG WEST TO NORTHWEST WINDS WILL CONTINUE THROUGH FRIDAY BEFORE DIMINISHING THIS WEEKEND AS THE HIGH PRESSURE SETTLES OVER THE SOUTHEAST. FREEZING SPRAY IS LIKELY WEDNESDAY NIGHT AND THURSDAY DUE TO THE COMBINATION OF STRONG WINDS...LARGE WAVES...AND ARCTIC AIR OVER THE LAKE. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023- ILZ032-ILZ033-ILZ039 UNTIL 4 AM WEDNESDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 4 AM WEDNESDAY. LM...DENSE FOG ADVISORY...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ740-LMZ741-LMZ742-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872- LMZ874-LMZ876-LMZ878 UNTIL 10 PM TUESDAY. GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM WEDNESDAY TO 6 AM THURSDAY. SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
613 PM CST TUE JAN 29 2013 .MESOSCALE DISCUSSION... 240 PM CST THE THREAT FOR HEAVY RAIN DEVELOPING AND POSSIBLY A COUPLE SEVERE STORMS CONTINUES. THE LATEST HAND ANALYSIS PLACES THE COLD FRONT JUST PAST THE MISSISSIPPI RIVER IN NORTHWEST IL WITH A SUBTLE PRE-FRONTAL TROUGH FROM JUST EAST OF ROCKFORD SOUTH TOWARD PEORIA. THIS PRE- FRONTAL TROUGH DOES HAVE AN INSTABILITY PLUME AIDED BY LOW TO MID 60S TEMPERATURES...AND LOW-LEVEL CAPE IS ANALYZED NEAR 100 J/KG WITH AROUND 300-500 J/KG OF SURFACE-BASED CAPE. THIS INSTABILITY THOUGH IS NOT LINING UP WITH ANY GREAT STORM ACTIVITY. SATELLITE AND RADAR TRENDS SHOW THAT A LARGE SWATH OF RAIN HAS EXPANDED FROM MO NORTHEAST THROUGH WESTERN IL AND SOUTHERN WI...STABILIZING MUCH OF THAT AREA. AT THE FRONT EDGE OF THIS...NEAR THE PRE-FRONTAL TROUGH...MORE CONVECTIVE-LIKE SHOWERS ARE PRESENT. THAT CONVECTION ON THE ILX RADAR HAS STRUGGLED TO BECOME WELL-DEFINED AND HAS MORE OF A QUASI-LINEAR MUSHY LOOK RIGHT NOW. LIGHTNING HAS BEEN SOMEWHAT SPORADIC AND REALLY HAS ONLY BEEN SEEN IN THE CLUSTER THAT IS NEARING CHICAGO...POSSIBLY ASSOCIATED WITH A WARM AIR ADVECTION FLANK AHEAD OF THE SYSTEM. OVERALL THE TREND HAS BEEN SLIGHTLY DOWN WITH NO LOCAL STORMS APPROACHING SEVERE LIMITS...AND A FEW 30-37 KT GUSTS OBSERVED. AT THIS TIME...IT REMAINS QUITE MARGINAL FOR SEVERE WEATHER AND MAY CONTINUE TO THROUGH MUCH OF THE AFTERNOON AS NO IMMEDIATE STRONG IMPULSES UPSTREAM ARE EVIDENT. TOWARD SUNSET AND INTO THIS EVENING...AREAS ALONG AND EAST OF I-55 WILL REMAIN FAVORED FOR STORM ACTIVITY ON THE NOSE OF AN INCREASING LOW LEVEL JET AND JUST MORE IMPROVED OVERALL FORCING. EXPLICIT CONVECTIVE MODELS AGREE THIS AREA WILL BE UNDER SOME STRONGER ACTIVITY THIS EVENING...BUT WHETHER THAT IS TO THE LIMITS TO FLIRT WITH SEVERE IS LOW CONFIDENCE. THE FORECAST DCAPE DOES INCREASE TO AROUND 400-500 J/KG ON THE NAM AND THE LOW-LEVEL SHEAR/HELICITY REMAINS HIGH IN THE STRONG ATMOSPHERIC WINDS. THIS MAY END UP BEING OUR BEST...ALBEIT NARROW WINDOW FOR SEVERE WEATHER. HEAVY RAIN REMAINS THE PRIMARY POTENTIAL HAZARD. WHILE IT IS A QUASI- LINEAR MUSHY LOOK RIGHT NOW...RAINFALL RATES ARE LIKELY VERY EFFICIENT IN ANY ACTIVITY AND WILL CONTINUE AS SUCH LATE THIS AFTERNOON INTO TONIGHT. A PERSISTENT FOCUS IS SEEN IN THE RAP AND NAM FORECASTS AS DEEP LAYER MOISTURE CONVERGENCE FURTHER INCREASES TONIGHT AS THE UPPER TROUGH INCHES EASTWARD. WIDESPREAD RAINFALL AMOUNTS OF ONE TO TWO AND A HALF INCHES LOOK LIKELY...WITH POTENTIALLY THE HIGHER END AMOUNTS BEING WIDESPREAD. WITH MUCH OF THIS GOING TOWARD RUNOFF...AT LEAST LOCALIZED PONDING TO POSSIBLE FLOODING WILL BE LIKELY. MTF && .DISCUSSION... 318 PM CST SHORT TERM...REST OF TODAY THROUGH WEDNESDAY NIGHT... FOR HEADLINES...KEPT FLOOD WATCH AS IS AND NO WINTER HEADLINES ARE EXPECTED AT THIS TIME. A DEEP TROUGH LIES ACROSS THE WESTERN US WITH ITS AXIS OVER THE GREAT PLAINS...WHILE A SURFACE LOW IS OVER ONTARIO. THE SURFACE LOWS COLD FRONT EXTENDS FROM THE LOW THROUGH CENTRAL WI TO ALONG THE MISSISSIPPI RIVER...AND IT IS SLOWLY MAKING ITS WAY INTO WESTERN IL. THE TEMPERATURE GRADIENT ACROSS THE FRONT IS RATHER IMPRESSIVE WITH 60 DEGREES IN PERU IL AND 38 DEGREES IN OTTUMWA IA...WITH JUST 176 MILES BETWEEN THE TWO CITIES. SHOWERS AND THUNDERSTORMS HAVE SPREAD INTO NORTHERN IL AHEAD OF THE COLD FRONT AND WILL CONTINUE TO SPREAD ACROSS THE CWA THIS AFTERNOON/EARLY EVENING. INDIVIDUAL CELLS HAVE BEEN CLOCKED AT 50-60 KT MOVING FROM THE SOUTHWEST TO THE NORTHEAST. SEVERE STORMS ARE STILL POSSIBLE THIS AFTERNOON...FOR MORE INFORMATION ON THE SEVERE WEATHER OUTLOOK AND RELATED PARAMETERS PLEASE SEE THE MESOSCALE DISCUSSION ABOVE. PWAT VALUES WILL BE IN EXCESS OF 1-1.5 INCHES THIS AFTERNOON/EVENING WITH DEWPOINTS CURRENTLY IN THE UPPER 50S TO LOW 60S FALLING OVERNIGHT. FLOW THROUGHOUT THE ATMOSPHERIC COLUMN IS ROUGHLY PARALLEL TO THE FRONT WHICH WILL INHIBIT THE FRONT FROM RAPIDLY PROGRESSING THROUGH THE CWA. TRAINING WILL ALSO BECOME AN ISSUE ALONG THE FRONT ALLOWING FOR IMPRESSIVE RAIN TOTALS. THE UPPER LEVEL JET STRETCHES FROM TEXAS THROUGH MINNESOTA BEFORE CURVING TOWARD QUEBEC. THE RIGHT JET ENTRANCE REGION LIES OVER SOUTHWEST WI/NORTHWEST IL ALMOST COLLOCATED WITH THE FRONT WHICH WILL CONTINUE TO SUPPORT THUNDERSTORM AND SHOWER FORMATION. BASED ON WHAT HAS PASSED OVER THE OFFICE THIS AFTERNOON...SOME OF THESE SHOWERS/STORMS WILL PRODUCE BRIEF INTENSE DOWNPOURS. THE JET AND FRONT CONTINUE ACROSS THE CWA TONIGHT WITH THE SOUTHERN JET STREAKS LEFT EXIT REGION POSSIBLY COUPLING WITH THE FRONT. AS SUCH EXPECTING PERIODS OF HEAVY RAIN TO CONTINUE OVERNIGHT. WHEN ALL IS SAID AND DONE...THINKING 1.5-2.5 INCHES OF RAIN ARE POSSIBLE ACROSS THE AREA. LOCALLY HIGHER AMOUNTS ARE CERTAINLY POSSIBLE. QUICKLY CHECKING THE OFFICES SOIL TEMPS...2 AND 4 INCHES BELOW THE SURFACE ARE ABOVE FREEZING AT 35 DEGREES WHILE 8 INCHES IS STILL FROZEN AT 27 DEGREES. AS SUCH EXPECTING PONDING OF WATER IN THE TYPICAL LOW LYING SPOTS...SINCE THE SOIL WILL NOT BE ABLE TO TAKE IN AS MUCH WATER AS USUAL. THEREFORE MADE NO ADJUSTMENTS TO THE FLOOD WATCH. TEMPS WILL BEGIN TO FALL OVERNIGHT WITH LOWS IN THE LOW 30S NEAR RFD TO ARND 50 NEAR RENSSELAER. WEDNESDAY... TEMPS WILL CONTINUE TO FALL WEDNESDAY MORNING WITH PRECIP TRANSITIONING TO SNOW AS A SWATH OF MOISTURE ASSOCIATED WITH THE 700 MB LOW SURGES NORTH. SOUNDINGS INDICATE A BRIEF PERIOD OF SLEET IS POSSIBLE DURING THE TRANSITION BUT NOT EXPECTING ANY SIGNIFICANT SLEET ACCUMULATION. EXPECTING AREAS AROUND RFD TO CHANGE OVER TO SNOW BEFORE 8AM...CHICAGO AROUND 3PM...AND NW INDIANA 4-6PM. FOR SNOW TOTALS...EXPECTING THE HIGHEST TOTALS IN FAR NW IL IN WINNEBAGO AND OGLE COUNTIES. THE NAM IS MUCH MORE EXCITED THAN THE GFS ABOUT THE SNOW POTENTIAL BUT BOTH MODELS SHOW THE SAME SET UP THAT IS FAVORABLE FOR MESOSCALE SNOW BANDS. 850-700 MB FRONTOGENESIS MOVES OVER NW IL/E IA EARLY WEDNESDAY MORNING WITH EPV VALUES BELOW 0 JUST ABOVE IT...INDICATING LOCALIZED INTENSE FORCING AND SYMMETRIC INSTABILITY. HOWEVER EXPECTING TEMPS TO BE ABOVE FREEZING AT THIS POINT. THE FRONTOGENESIS AND INSTABILITY SHIFT EASTWARD THROUGH THE MORNING AND THEN WEAKEN AFTER NOON. THE LEFT JET EXIT REGION OF THE UPPER LEVEL JET WILL ALSO BE OVER NORTHERN IL THROUGH WEDNESDAY AFTERNOON SO SYNOPTIC-SCALE LIFT SHOULD NOT BE AN ISSUE. WHILE MESOSCALE BANDS OF RAIN OR SNOW ARE VERY LIKELY TOMORROW...THESE FEATURES ARE HARD TO PINPOINT EVEN THIS FAR OUT. THEREFORE WENT WITH 3-5 INCHES OF SNOW OVER WINNEBAGO AND OGLE COUNTIES TOMORROW...BUT THIS NUMBER COULD EASILY BE HIGHER IF A BAND OF SNOW SETS UP. THE BIG QUESTIONS ARE WILL THE BEST FORCING ALIGN WITH SNOW OR RAIN...HOW LONG WILL THE FORCING LAST...AND WHERE WILL THE MESOSCALE BAND SET UP. AS MENTIONED BEFORE...THE FRONTOGENESIS WEAKENS AND STABILITY INCREASES IN THE AFTERNOON AS THE SNOW SPREADS ACROSS THE REST OF THE CWA. SO INTENSE MESOSCALE BANDS ARE NOT AS LIKELY...BUT FORCING FROM THE UPPER LEVEL JET STILL LOOKS FAVORABLE FOR A LITTLE SNOW. AS SUCH EXPECTING 1 TO 3 INCHES OF SNOW ACROSS BOONE AND MCHENRY COUNTIES...AND THEN AN INCH OR LESS EVERYWHERE ELSE. SNOW ENDS FROM WEST TO EAST...WITH NO SNOW EXPECTED AFTER MIDNIGHT ON WEDNESDAY. TEMPS CONTINUE TO TUMBLE TO THE TEENS OR SINGLE DIGITS WEDNESDAY NIGHT. WINDS 20-25 MPH WITH GUSTS UP TO 30 MPH SLOWLY WEAKEN OVERNIGHT...BUT EXPECTING WINDCHILLS TO BE BTWN 1 AND -10. JEE EXTENDED PERIOD...THURSDAY THROUGH TUESDAY... MAIN FORECAST CONCERN IN EXTENDED PERIOD DEALS WITH REINFORCEMENT OF ARCTIC COLD THURSDAY NIGHT/FRIDAY...AND THE POTENTIAL FOR LIGHT SNOW FRIDAY NIGHT/SATURDAY WITH A COUPLE CLIPPER-TYPE SYSTEMS ON THE BACK SIDE OF THE RETREATING LOW LEVEL COLD AIR. MEDIUM RANGE GUIDANCE APPEARS TO BE IN GOOD AGREEMENT AT THE START OF THE PERIOD THURSDAY MORNING...WITH DEEP SURFACE LOW LIFTING NORTHEAST ACROSS EASTERN QUEBEC AND DEEP UPPER LEVEL TROUGH ACROSS MUCH OF EASTERN NORTH AMERICA. ALL OF THE GLOBAL MODELS DEPICT ANOTHER STRONG SHORT WAVE DIGGING SOUTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES REGION THROUGH THE DAY... ACCOMPANIED BY A STRONG PUSH OF COLD ARCTIC AIR WITH 850 MB TEMPS OF -22 TO -24 C MOVING INTO THE CWA BY THURSDAY EVENING. MODEL SOUNDINGS AND TIME/HEIGHT SERIES INDICATE DRY MID/UPPER LEVELS AHEAD OF THIS DIGGING SHORT WAVE...WITH MODEL GENERATED QPF LIMITED TO THE MID/LOWER MISSOURI RIVER VALLEY INTO THE LOWER OHIO VALLEY THURSDAY AFTERNOON AND EVENING...THE COMBINATION OF DIGGING VORT...COLD ADVECTION WITH VERY COLD ARCTIC AIR...AND RELATIVELY MOIST LOW LEVELS ALL POINT TO THE POTENTIAL FOR AT LEAST SOME FLURRIES ACROSS THE FORECAST AREA THURSDAY AFTERNOON/EVENING. TEMPS...WHICH SHOULD ONLY TOP OUT IN THE MID TEENS NORTH AND LOWER 20S SOUTH AFTER WEDNESDAYS COLD FRONT...SHOULD EASILY FALL TO AROUND/BELOW ZERO ACROSS NORTH CENTRAL IL BY SUNRISE FRIDAY AND TO PERHAPS THE LOW POSITIVE SINGLE DIGITS ACROSS THE SOUTH WITH STRONG LOW LEVEL COLD ADVECTION THURSDAY NIGHT. HAVE TRENDED COLDER TOWARD THE 00Z GEFS MOS...AND A FEW DEGREES BELOW THAT AROUND ROCKFORD. THIS MAY NOT BE COLD ENOUGH ESPECIALLY IF SIGNIFICANT SNOW PACK IS IN PLACE AFTER WEDNESDAY. WINDS SHOULD REMAIN BLUSTERY ESPECIALLY IN THE EVENING WITH THE ENHANCED GRADIENT TO THE EAST OF THE CANADIAN HIGH BUILDING SOUTHEAST THROUGH THE PLAINS...SUPPORTING WIND CHILLS -10 TO -20 F OVERNIGHT. THE MID-LEVEL SHORT WAVE TROUGH AXIS IS PROGGED TO MOVE OFF TO THE SOUTHEAST OF THE FORECAST AREA EARLY FRIDAY MORNING...WITH FAIRLY STRONG HEIGHT RISES DEVELOPING IN ITS WAKE. COLD SURFACE HIGH PRESSURE CENTER WILL CONTINUE TO PUSH SOUTHEAST THROUGH THE LOWER OHIO VALLEY INTO TENNESSEE BY EVENING. CORE OF THE COLDEST AIR WILL SHIFT OFF TO THE EAST/SOUTHEAST BY AFTERNOON...THOUGH COLD MORNING START AND SHALLOW MIXED LAYER BENEATH SUBSIDENCE INVERSION WILL ALLOW ONLY MARGINAL MODERATION OF TEMPS AT THE SURFACE. HAVE ALSO TRENDED COLDER WITH MAXES FRIDAY TOWARD COLDER GFS/GEFS MOS NUMBERS. NORTHERN EXTENT OF SURFACE RIDGE AXIS MOVES ACROSS THE CWA FRIDAY EVENING...WITH WARM ADVECTION ALREADY DEVELOPING ON THE WESTERN PERIPHERY OF THE RETREATING LOW LEVEL COLD AIR DOME. WITH NORTHWEST FLOW ALOFT ON THE BACK SIDE OF THE DEPARTING LONG-WAVE UPPER TROUGH THIS SETS THE STAGE FOR A COUPLE OF MODEST SHORT WAVES TO BRING A COUPLE POTENTIAL PERIODS OF LIGHT SNOW TO THE REGION FRIDAY NIGHT AND SATURDAY. ECMWF/GFS 12Z RUNS REMAIN IN FAIRLY GOOD AGREEMENT IN DEVELOPING LIGHT QPF ACROSS THE AREA WITH A WEAK SURFACE LOW MOVING ACROSS NORTHERN ILLINOIS SATURDAY. UPPER JET CORE THEN SHIFTS SLOWLY EAST/NORTHEAST ACROSS THE NORTHERN/CENTRAL GREAT LAKES SATURDAY NIGHT...AS HIGH PRESSURE RIDGE MOVES ACROSS THE REGION THROUGH SUNDAY. WITH COLD CORE OF UPPER TROUGH OFF TO THE EAST...TEMPS MODERATE BACK TO MORE SEASONABLE LEVELS SATURDAY (MID-UPPER 20S) AND PERHAPS A BIT ABOVE (30S) SUNDAY AS WINDS SHIFT SOUTH IN THE AFTERNOON WEST OF THE RIDGE AXIS. MODERATION LOOKS TO CONTINUE MONDAY AS ECMWF/GFS REMAIN IN GOOD AGREEMENT IN TAKING AN AREA OF SURFACE LOW PRESSURE NORTH OF THE CWA ACROSS MN/WI. DRY HIGH PRESSURE BLOCKS MOISTURE RETURN FROM THE SOUTH FOR THE MOST PART... WITH NEXT CHANCE OF ORGANIZED PRECIP OCCURRING WITH THE COLD FRONT ASSOCIATED WITH THIS LOW MONDAY/MONDAY NIGHT...AND MAINLY ACROSS THE SOUTHEASTERN CWA. GEM MEANWHILE DURING THIS PERIOD BECOMES A COLD OUTLIER...WITH CONSISTENT ECMWF/GFS SOLUTIONS FAVORED AT THIS DISTANCE. THIS WOULD INDICATE COOLER/SEASONAL TEMPS RETURN TUESDAY. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 00Z... * CHANCE OF THUNDERSTORMS FOR ANOTHER HOUR OR SO AS LEADING EDGE OF WIDESPREAD RAIN PUSHES THROUGH THE AREA. * PERSISTENT MODERATE TO OCCASIONALLY HEAVY RAIN UNTIL AROUND 03Z. * CIGS LOWERING TO PREVAILING IFR FROM LATE EVENING THROUGH EARLY TOMORROW AFTERNOON. * WIND SHIFT TO NLY-NNELY ARND 03Z FOLLOWING FRONTAL PASSAGE, KREIN //DISCUSSION...UPDATED 00Z... THE LINE OF HEAVIEST RAIN AND SCATTERED THUNDERSTORMS HAS PUSHED EAST OF ALL TERMINALS EXCEPT GYY...WHICH WILL BE IMPACTED SHORTHLY. WHILE THE HEAVIEST RAIN AND THUNDERSTORM POTENTIAL IS ALONG THIS LINE...THERE IS STILL A SMALL LINGERING CHANCE OF SOME ISOLATED THUNDER FOR A SHORT TIME FOLLOWING THE PASSAGE OF THIS LINE. FOR THE REMAINDER OF THE EVENING AND OVERNIGHT...WIDESPREAD RAIN AND IFR CIGS WILL COVER THE AREA AND IMPACT ALL TERMINALS. WINDS WILL SHIFT TO NLY-NNELY EARLY THIS EVENING FOLLOWING THE PASSAGE OF THE COLD FRONT...BUT IT WILL BE QUITE SOME TIME UNTIL THE COOLER...DRIER AIR FILTERS OVER THE REGION. RAIN SHOULD BEGIN TO TAPER OFF TOMORROW MORNING AND TRANSITION OVER TO LIGHT SNOW BY EARLY AFTERNOON. THE IFR CIGS WILL PERSIST UNTIL THE DRIER AIR ASSOCIATED WITH THE COOLER AIRMASS OVERSPREADS THE REGION. SO...BY EARLY TOMORROW AFTERNOON...EXPECT THE BIGGEST IMPROVEMENT TO FLIGHT CONDITIONS...IMPROVING TO MVFR...BUT AT THAT POINT...LIGHT SNOW SHOULD BEGIN WITH SOME ACCUMULATION POSSIBLE. KREIN //ORD AND MDW CONFIDENCE...UPDATED 00Z... * HIGH CONFIDENCE IN PCPN TRENDS. * MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS. * MEDIUM CONFIDENCE IN CIG/VIS TRENDS...BUT LOWER CONFIDENCE IN EXACT TIMING OF IMPROVEMENT. KREIN //OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z... THURSDAY...CHANCE OF FLURRIES IN THE AFTERNOON/EVENING. MVFR CIGS POSSIBLE. WEST WINDS GUSTING TO 25-30KT. FRIDAY...VFR EARLY. CHANCE OF SNOW WITH MVFR CIGS/VIS OVERNIGHT. SATURDAY...CHANCE OF SNOW WITH MVFR CIGS/VIS EARLY...THE VFR OVERNIGHT. SUNDAY...VFR. WX NIL. MONDAY...SLIGHT CHANCE RAIN/SNOW. MVFR CIGS/VIS POSSIBLE. KREIN && .MARINE... 1248 PM CST SEVERAL WAVES OF LOW PRESSURE WILL RIDE UP A SLOW MOVING COLD FRONT TONIGHT THROUGH WEDNESDAY AFTERNOON...AS THE FRONT TRAVERSES LAKE MICHIGAN. STRONG SOUTH TO SOUTHWEST WINDS AHEAD OF THE FRONT HAVE PROMPTED A SMALL CRAFT ADVISORY FOR THE IL AND IN NEARSHORE. WINDS WILL SUBSIDE AS THE FRONT APPROACHES THE ILLINOIS WATERS LATE THIS AFTERNOON...AND THE INDIANA WATERS THIS EVENING. AREAS OF DENSE FOG ARE POSSIBLE INTO THIS EVENING...MAINLY OVER THE SOUTH HALF OF THE LAKE...AS UNSEASONABLY MILD AND HUMID AIR MOVES OVER THE CHILLY WATER. BEHIND THE COLD FRONT...NORTHWEST WINDS WILL RAMP UP AS THE FINAL WAVE OF LOW PRESSURE MOVES INTO EASTERN CANADA AND INTENSIFIES...WHILE STRONG HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS. GALE FORCE WINDS WILL DEVELOP BY MID MORNING WEDNESDAY AND SLOWLY DIMINISH BELOW GALE FORCE THURSDAY MORNING. THE GALE WATCH WILL BE UPGRADED TO A GALE WARNING WITH THE 300 PM GLFLM ISSUANCE. STRONG WEST TO NORTHWEST WINDS WILL CONTINUE THROUGH FRIDAY BEFORE DIMINISHING THIS WEEKEND AS THE HIGH PRESSURE SETTLES OVER THE SOUTHEAST. FREEZING SPRAY IS LIKELY WEDNESDAY NIGHT AND THURSDAY DUE TO THE COMBINATION OF STRONG WINDS...LARGE WAVES...AND ARCTIC AIR OVER THE LAKE. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019 UNTIL 4 AM WEDNESDAY. FLOOD WATCH...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-ILZ021- ILZ022-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 4 AM WEDNESDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 4 AM WEDNESDAY. LM...DENSE FOG ADVISORY...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 10 PM TUESDAY. GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM WEDNESDAY TO 6 AM THURSDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
959 PM EST TUE JAN 29 2013 .UPDATE... THE NEAR TERM SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 337 PM EST TUE JAN 29 2013 NUMEROUS WEATHER HAZARDS WILL ACCOMPANY AN EXTREMELY POTENT SYSTEM IMPACTING THE REGION THROUGH TOMORROW. VERY UNSEASONABLY WARM AND MOIST CONDITIONS WILL BE IN PLACE THROUGH TONIGHT. AHEAD OF A STRONG COLD FRONT SWEEPING THROUGH THE REGION...THE POTENTIAL WILL EXIST FOR THUNDERSTORMS...HEAVY RAINFALL...FLOODING AND DAMAGING WINDS. POTENTIAL FOR STRONG WINDS WILL CONTINUE BEHIND THE FRONTAL BOUNDARY ON WEDNESDAY...AND FLOODING MAY LAST FOR SEVERAL DAYS OR MORE. && .NEAR TERM /REST OF TONIGHT/... ISSUED AT 942 PM EST TUE JAN 29 2013 UPDATE... LINE OF STRONG TO SEVERE THUNDERSTORMS IS WELL OUT AHEAD OF THE COLD FRONT AND CURRENTLY PUSHING EASTWARD THROUGH ILLINOIS AND WESTERN KENTUCKY. TEMPS ACROSS CENTRAL INDIANA HAVE BEEN SLOWLY RISING A FEW DEGREES OVER THE LAST FEW HOURS AS STRONG LOW LEVEL JET ADVECTS WARM AIR AHEAD OF IT. SO...LOSS OF DIURNAL HEATING HAS HAD LITTLE AFFECT ON ENVIRONMENT. INSTABILITY LOOKS MOST FAVORABLE FOR SEVERE STORMS ACROSS THE SOUTHERN PORTIONS OF FORECAST AREA PER LATEST LAPS ANALYSES. PREVIOUS DISCUSSION... FOCUS OF THE NEAR TERM REMAINS ON SEVERE WEATHER CHANCES AS WELL AS POSSIBLE HEAVY RAINFALL/FLOODING POSSIBILITIES TONIGHT. THE PERIOD BEGINS WITH GOOD SHORT TERM MODEL AGREEMENT AS TO THE LOCATION OF KEY FEATURES THAT MAY BRING POSSIBLE SEVERE TO PORTIONS OF THE FORECAST AREA TONIGHT. AT 00Z/WED...THE LOW PRESSURE CENTER IS PROGGED TO BE OVER CENTRAL MISSOURI...WITH ONGOING CONVECTION POSSIBLY ALREADY IN THE FORM OF A SQUALL LINE ALONG A STRONG COLD FRONT STRETCHED FROM NORTHWEST ILLINOIS...DOWN THROUGH CENTRAL MISSOURI...INTO EASTERN OKLAHOMA/WESTERN ARKANSAS. THERE DOES APPEAR TO BE SOME DIFFERENCES IN SPEED/TIMING OF THE FRONT INTO THE FORECAST AREA...WITH THE HRRR AND RAP INTO THE AREA A BIT QUICKER THE THE NAM AND GFS. PERSONAL EXPERIENCE HAS SHOWN THAT THESE COLD FRONT/SQUALL LINE FEATURES TEND TO COME IN A BIT QUICKER THAN SOMETIMES EXPECTED. THEREFORE...DECIDED TO TREND TOWARD THE HRRR/RUC SOLNS. AS WAS MENTIONED IN PREVIOUS DISCUSSIONS...DYNAMICS WILL NOT BE AN ISSUE WITH THIS SYSTEM AS THE FRONT APPROACHES. A LOW LEVEL JET AOA 80 KTS AT 850 MB IS EXPECTED TO DEVELOP OUT AHEAD OF THE FRONT THIS EVENING AND WILL TRANSLATE INTO OUR AREA TONIGHT. WITH 50 KT WINDS LOCATED APPROXIMATELY 1000-1500 FEET ABOVE THE SURFACE TONIGHT...DAMAGING WINDS MAY BECOME A REAL THREAT WITH ANY STORMS THAT ARE ABLE TO REMAIN ORGANIZED AS THEY PUSH INTO THE FORECAST AREA. ONE LIMITING FACTOR FOR CONVECTION REMAINING ORGANIZED INTO THE OVERNIGHT HOURS IS INSTABILITY. SFC-BASED CAPE LOOKS TO BE IN THE UNDER 200 J/KG RANGE...WHILE MUCAPE GIVES SLIGHTLY HIGHER VALUES OF 200-400 J/KG AS THE FRONT MOVES INTO THE AREA. WITH THE STRONG DYNAMICS AVAILABLE...WILL CONTINUE DAMAGING WINDS REFERENCE IN THE GRIDS. ALSO KEEP IN MIND THAT WITH AMPLE LOW LEVEL SHEAR...0-1 HELICITIES AOA 400-500 M2/S2...AN ISOLATED TORNADO CANNOT BE RULED OUT. THE BEST TIMING FOR SEVERE LOOKS TO START AT APPROXIMATELY 04-05Z ACROSS WESTERN PORTIONS OF THE FORECAST AREA...TO ABOUT 10-11Z OVER THE EAST. JUST ONE OTHER NOTE TO MENTION...THE HRRR ILLUSTRATES A LINE OF CONVECTION DEVELOPING OUT AHEAD OF THE MAIN SQUALL LINE. TO A LESSER EXTENT...THE RAP ALSO DEPICTS A SIMILAR SCENARIO. WHILE THIS FORECAST HAS TAKEN THIS INTO CONSIDERATION...IT COULD STILL ALLOW FOR AN EARLIER ONSET THAN FORECAST. HEAVY RAINFALL IS ALSO IN PLAY TONIGHT AS MOISTURE HAS CONTINUED TO STREAM NORTH INTO THE AREA. A PACIFIC TROPICAL PLUME OF MOISTURE HAS BEEN EVIDENT ALL DAY ON WATER VAPOR IMAGERY STREAMING NORTHWEST INTO LOWER MISSOURI/MID MISSISSIPPI/OHIO RIVER VALLEY STATES. COUPLE THAT WITH 60 DEGREE DEWPOINTS CURRENTLY ON THE SOUTHWESTERN DOORSTEP OF THE FORECAST AREA. PWATS TONIGHT AHEAD OF THE FRONT LOOK TO REACH UPWARDS OF 1.40-1.50 INCHES...YIELDING A PERCENT OF NORMAL OF AROUND 300 PERCENT. WOULD NOT BE SURPRISED TO SEE A WIDESPREAD 1 TO 1.5 INCH RAINFALL...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... ISSUED AT 337 PM EST TUE JAN 29 2013 SHORT TERM PERIOD SEES A DIFFERENT SET OF CHALLENGES. ONE OF THE INITIAL CHALLENGES WILL BE STRONG WINDS AFTER THE COLD FRONT SWEEPS THROUGH THE AREA AND A DRY SLOT APPROACHES THE FORECAST AREA DURING THE AFTERNOON HOURS. SUSTAINED WINDS AROUND 20-25 KTS...WITH THE POSSIBILITY TO TAP 40 KT WINDS FROM APPROX 850 MB AS BOUNDARY LAYER MIXES OUT. A WIND ADVISORY MAY BE NEED FOR A TIME IN THE LATE MORNING TO EARLY EVENING HOURS ON WEDNESDAY. ADDITIONALLY...SOME LIGHT SNOW SHOWERS MAY WRAP AROUND AND AFFECT MAINLY NORTHERN PORTIONS OF THE FORECAST AREA WEDNESDAY NIGHT AS THE UPPER TROUGH FINALLY PASSES THROUGH. NOT CURRENTLY EXPECTING MUCH IN THE WAY OF ACCUMULATION. ANOTHER UPPER TROUGH AND COLD FRONT PUSHES INTO THE THROUGH THE AREA LATE THURSDAY INTO THURSDAY NIGHT...BRINGING AN ADDITIONAL CHANCE FOR SNOW AND FALLING TEMPS. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ISSUED AT 144 PM EST TUE JAN 29 2013 .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE EXTENDED PERIOD WILL NOT BE NEARLY AS ACTIVE AS THE FIRST FEW DAYS OF THE FORECAST. FIRST OFF A SHORT WAVE TROUGH MOVING THROUGH THE GREAT LAKES REGION MAY BRING A FEW SNOW SHOWERS TO CENTRAL INDIANA AT THE BEGINNING OF THIS PERIOD. TEMPS/THICKNESS ALL LOOK COLD ENOUGH FOR PLAIN SNOW DURING THIS TIME. ATTM ACCUMULATIONS APPEAR TO BE AN INCH OR LESS. AFTER A COLD SHOT OF AIR THU AND FRIDAY...TEMPERATURES WILL GRADUALLY MODERATE TO CLIMO OVER THE WEEKEND AND INTO NEXT WEEK. SECOND HALF OF THE WEEKEND LOOKS DRY AND INTO EARLY NEXT WEEK. ENSEMBLES SHOW SOME PRECIP BY NEXT MONDAY/MONDAY NIGHT. TEMPERATURES LOOK WARM ENOUGH FOR A SNOW/RAIN MIX ACROSS A GOOD PORTION OF THE AREA. HAVE SMALL MINIMAL PRECIP CHANCES IN DURING THIS TIME. && .AVIATION /DISCUSSION FOR THE 30/03Z IND TAF UPDATE/... ISSUED AT 920 PM EST TUE JAN 29 2013 PULLED THE SHOWERS AT IND BASED ON RADAR...OTHERWISE NO CHANGES. PREVIOUS DISCUSSION FOLLOWS... POTENT SPRING-LIKE WEATHER SYSTEM IS EXPECTED TO BRING STRONG TO SEVERE THUNDERSTORMS TO CENTRAL INDIANA LATE THIS EVENING AND EARLY OVERNIGHT. THE RAPID REFRESH REFLECTIVITY PROGS AND AWIPS-DISTANCE SPEED TOOL SUGGEST A LINE OF STORMS SHOULD REACH HUF AND LAF AROUND 04Z AND IND AND BMG AROUND 06Z WITH PLENTY OF TRAILING RAIN. BASED ON LIGHTNING DATA AND EXPECTED TIMING...WENT WITH IFR TEMPO THUNDERSTORM GROUP AS THE ACTIVITY REACHES THE TERMINALS ALONG WITH SOUTHWEST WINDS TO 30 KNOTS AND WIND GUSTS TO 40 KNOTS. HIGHER GUSTS ARE POSSIBLE WITH THE AREA IN A SLIGHT RISK TONIGHT...SO MAY NEED TO EVENTUALLY UP THOSE GUSTS TO SEVERE CRITERIA. FLIGHT CONDITIONS WILL START AS MVFR AND COULD DROP TO IFR OVERNIGHT BEFORE COMING UP TO VFR BY TOMORROW AFTERNOON BEHIND THE FRONTAL SYSTEM. WOULD NOT RULE OUT A FEW RAIN SHOWERS TOMORROW AFTERNOON EVEN MIXING WITH SNOW...BUT COVERAGE SHOULD BE ON THE LOW SIDE...SO LEFT THEM OUT FOR NOW. BASED ON VWP PROFILE DATA ALONG WITH BUFKIT...MOVED THE LOW LEVEL WIND SHEAR UP A FEW HOURS. WINDS SHOULD STAY UP TOMORROW WITH GUSTS TO 30 KNOTS OR MORE WITH DIRECTION SHIFTING TO WEST BEHIND THE FRONTAL SYSTEM. && .IND WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH WEDNESDAY MORNING FOR INZ021-028>031-035>049- 051>057-060>065-067>072. && $$ SYNOPSIS...MRD NEAR TERM...MRD/TDUD SHORT TERM...MRD LONG TERM....SMF AVIATION...MK
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
820 PM EST TUE JAN 29 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 337 PM EST TUE JAN 29 2013 NUMEROUS WEATHER HAZARDS WILL ACCOMPANY AN EXTREMELY POTENT SYSTEM IMPACTING THE REGION THROUGH TOMORROW. VERY UNSEASONABLY WARM AND MOIST CONDITIONS WILL BE IN PLACE THROUGH TONIGHT. AHEAD OF A STRONG COLD FRONT SWEEPING THROUGH THE REGION...THE POTENTIAL WILL EXIST FOR THUNDERSTORMS...HEAVY RAINFALL...FLOODING AND DAMAGING WINDS. POTENTIAL FOR STRONG WINDS WILL CONTINUE BEHIND THE FRONTAL BOUNDARY ON WEDNESDAY...AND FLOODING MAY LAST FOR SEVERAL DAYS OR MORE. && .NEAR TERM /TONIGHT/... ISSUED AT 337 PM EST TUE JAN 29 2013 FOCUS OF THE NEAR TERM REMAINS ON SEVERE WEATHER CHANCES AS WELL AS POSSIBLE HEAVY RAINFALL/FLOODING POSSIBILITIES TONIGHT. THE PERIOD BEGINS WITH GOOD SHORT TERM MODEL AGREEMENT AS TO THE LOCATION OF KEY FEATURES THAT MAY BRING POSSIBLE SEVERE TO PORTIONS OF THE FORECAST AREA TONIGHT. AT 00Z/WED...THE LOW PRESSURE CENTER IS PROGGED TO BE OVER CENTRAL MISSOURI...WITH ONGOING CONVECTION POSSIBLY ALREADY IN THE FORM OF A SQUALL LINE ALONG A STRONG COLD FRONT STRETCHED FROM NORTHWEST ILLINOIS...DOWN THROUGH CENTRAL MISSOURI...INTO EASTERN OKLAHOMA/WESTERN ARKANSAS. THERE DOES APPEAR TO BE SOME DIFFERENCES IN SPEED/TIMING OF THE FRONT INTO THE FORECAST AREA...WITH THE HRRR AND RAP INTO THE AREA A BIT QUICKER THE THE NAM AND GFS. PERSONAL EXPERIENCE HAS SHOWN THAT THESE COLD FRONT/SQUALL LINE FEATURES TEND TO COME IN A BIT QUICKER THAN SOMETIMES EXPECTED. THEREFORE...DECIDED TO TREND TOWARD THE HRRR/RUC SOLNS. AS WAS MENTIONED IN PREVIOUS DISCUSSIONS...DYNAMICS WILL NOT BE AN ISSUE WITH THIS SYSTEM AS THE FRONT APPROACHES. A LOW LEVEL JET AOA 80 KTS AT 850 MB IS EXPECTED TO DEVELOP OUT AHEAD OF THE FRONT THIS EVENING AND WILL TRANSLATE INTO OUR AREA TONIGHT. WITH 50 KT WINDS LOCATED APPROXIMATELY 1000-1500 FEET ABOVE THE SURFACE TONIGHT...DAMAGING WINDS MAY BECOME A REAL THREAT WITH ANY STORMS THAT ARE ABLE TO REMAIN ORGANIZED AS THEY PUSH INTO THE FORECAST AREA. ONE LIMITING FACTOR FOR CONVECTION REMAINING ORGANIZED INTO THE OVERNIGHT HOURS IS INSTABILITY. SFC-BASED CAPE LOOKS TO BE IN THE UNDER 200 J/KG RANGE...WHILE MUCAPE GIVES SLIGHTLY HIGHER VALUES OF 200-400 J/KG AS THE FRONT MOVES INTO THE AREA. WITH THE STRONG DYNAMICS AVAILABLE...WILL CONTINUE DAMAGING WINDS REFERENCE IN THE GRIDS. ALSO KEEP IN MIND THAT WITH AMPLE LOW LEVEL SHEAR...0-1 HELICITIES AOA 400-500 M2/S2...AN ISOLATED TORNADO CANNOT BE RULED OUT. THE BEST TIMING FOR SEVERE LOOKS TO START AT APPROXIMATELY 04-05Z ACROSS WESTERN PORTIONS OF THE FORECAST AREA...TO ABOUT 10-11Z OVER THE EAST. JUST ONE OTHER NOTE TO MENTION...THE HRRR ILLUSTRATES A LINE OF CONVECTION DEVELOPING OUT AHEAD OF THE MAIN SQUALL LINE. TO A LESSER EXTENT...THE RAP ALSO DEPICTS A SIMILAR SCENARIO. WHILE THIS FORECAST HAS TAKEN THIS INTO CONSIDERATION...IT COULD STILL ALLOW FOR AN EARLIER ONSET THAN FORECAST. HEAVY RAINFALL IS ALSO IN PLAY TONIGHT AS MOISTURE HAS CONTINUED TO STREAM NORTH INTO THE AREA. A PACIFIC TROPICAL PLUME OF MOISTURE HAS BEEN EVIDENT ALL DAY ON WATER VAPOR IMAGERY STREAMING NORTHWEST INTO LOWER MISSOURI/MID MISSISSIPPI/OHIO RIVER VALLEY STATES. COUPLE THAT WITH 60 DEGREE DEWPOINTS CURRENTLY ON THE SOUTHWESTERN DOORSTEP OF THE FORECAST AREA. PWATS TONIGHT AHEAD OF THE FRONT LOOK TO REACH UPWARDS OF 1.40-1.50 INCHES...YIELDING A PERCENT OF NORMAL OF AROUND 300 PERCENT. WOULD NOT BE SURPRISED TO SEE A WIDESPREAD 1 TO 1.5 INCH RAINFALL...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... ISSUED AT 337 PM EST TUE JAN 29 2013 SHORT TERM PERIOD SEES A DIFFERENT SET OF CHALLENGES. ONE OF THE INITIAL CHALLENGES WILL BE STRONG WINDS AFTER THE COLD FRONT SWEEPS THROUGH THE AREA AND A DRY SLOT APPROACHES THE FORECAST AREA DURING THE AFTERNOON HOURS. SUSTAINED WINDS AROUND 20-25 KTS...WITH THE POSSIBILITY TO TAP 40 KT WINDS FROM APPROX 850 MB AS BOUNDARY LAYER MIXES OUT. A WIND ADVISORY MAY BE NEED FOR A TIME IN THE LATE MORNING TO EARLY EVENING HOURS ON WEDNESDAY. ADDITIONALLY...SOME LIGHT SNOW SHOWERS MAY WRAP AROUND AND AFFECT MAINLY NORTHERN PORTIONS OF THE FORECAST AREA WEDNESDAY NIGHT AS THE UPPER TROUGH FINALLY PASSES THROUGH. NOT CURRENTLY EXPECTING MUCH IN THE WAY OF ACCUMULATION. ANOTHER UPPER TROUGH AND COLD FRONT PUSHES INTO THE THROUGH THE AREA LATE THURSDAY INTO THURSDAY NIGHT...BRINGING AN ADDITIONAL CHANCE FOR SNOW AND FALLING TEMPS. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ISSUED AT 144 PM EST TUE JAN 29 2013 .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE EXTENDED PERIOD WILL NOT BE NEARLY AS ACTIVE AS THE FIRST FEW DAYS OF THE FORECAST. FIRST OFF A SHORT WAVE TROUGH MOVING THROUGH THE GREAT LAKES REGION MAY BRING A FEW SNOW SHOWERS TO CENTRAL INDIANA AT THE BEGINNING OF THIS PERIOD. TEMPS/THICKNESS ALL LOOK COLD ENOUGH FOR PLAIN SNOW DURING THIS TIME. ATTM ACCUMULATIONS APPEAR TO BE AN INCH OR LESS. AFTER A COLD SHOT OF AIR THU AND FRIDAY...TEMPERATURES WILL GRADUALLY MODERATE TO CLIMO OVER THE WEEKEND AND INTO NEXT WEEK. SECOND HALF OF THE WEEKEND LOOKS DRY AND INTO EARLY NEXT WEEK. ENSEMBLES SHOW SOME PRECIP BY NEXT MONDAY/MONDAY NIGHT. TEMPERATURES LOOK WARM ENOUGH FOR A SNOW/RAIN MIX ACROSS A GOOD PORTION OF THE AREA. HAVE SMALL MINIMAL PRECIP CHANCES IN DURING THIS TIME. && .AVIATION /DISCUSSION FOR THE 30/03Z IND TAF UPDATE/... ISSUED AT 920 PM EST TUE JAN 29 2013 PULLED THE SHOWERS AT IND BASED ON RADAR...OTHERWISE NO CHANGES. PREVIOUS DISCUSSION FOLLOWS... POTENT SPRING-LIKE WEATHER SYSTEM IS EXPECTED TO BRING STRONG TO SEVERE THUNDERSTORMS TO CENTRAL INDIANA LATE THIS EVENING AND EARLY OVERNIGHT. THE RAPID REFRESH REFLECTIVITY PROGS AND AWIPS-DISTANCE SPEED TOOL SUGGEST A LINE OF STORMS SHOULD REACH HUF AND LAF AROUND 04Z AND IND AND BMG AROUND 06Z WITH PLENTY OF TRAILING RAIN. BASED ON LIGHTNING DATA AND EXPECTED TIMING...WENT WITH IFR TEMPO THUNDERSTORM GROUP AS THE ACTIVITY REACHES THE TERMINALS ALONG WITH SOUTHWEST WINDS TO 30 KNOTS AND WIND GUSTS TO 40 KNOTS. HIGHER GUSTS ARE POSSIBLE WITH THE AREA IN A SLIGHT RISK TONIGHT...SO MAY NEED TO EVENTUALLY UP THOSE GUSTS TO SEVERE CRITERIA. FLIGHT CONDITIONS WILL START AS MVFR AND COULD DROP TO IFR OVERNIGHT BEFORE COMING UP TO VFR BY TOMORROW AFTERNOON BEHIND THE FRONTAL SYSTEM. WOULD NOT RULE OUT A FEW RAIN SHOWERS TOMORROW AFTERNOON EVEN MIXING WITH SNOW...BUT COVERAGE SHOULD BE ON THE LOW SIDE...SO LEFT THEM OUT FOR NOW. BASED ON VWP PROFILE DATA ALONG WITH BUFKIT...MOVED THE LOW LEVEL WIND SHEAR UP A FEW HOURS. WINDS SHOULD STAY UP TOMORROW WITH GUSTS TO 30 KNOTS OR MORE WITH DIRECTION SHIFTING TO WEST BEHIND THE FRONTAL SYSTEM. && .IND WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH FROM 7 PM EST THIS EVENING THROUGH WEDNESDAY MORNING FOR INZ021-028>031-035>049-051>057-060>065-067>072. && $$ SYNOPSIS...MRD NEAR TERM...MRD SHORT TERM...MRD LONG TERM....SMF AVIATION...MK
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
610 PM EST TUE JAN 29 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 337 PM EST TUE JAN 29 2013 NUMEROUS WEATHER HAZARDS WILL ACCOMPANY AN EXTREMELY POTENT SYSTEM IMPACTING THE REGION THROUGH TOMORROW. VERY UNSEASONABLY WARM AND MOIST CONDITIONS WILL BE IN PLACE THROUGH TONIGHT. AHEAD OF A STRONG COLD FRONT SWEEPING THROUGH THE REGION...THE POTENTIAL WILL EXIST FOR THUNDERSTORMS...HEAVY RAINFALL...FLOODING AND DAMAGING WINDS. POTENTIAL FOR STRONG WINDS WILL CONTINUE BEHIND THE FRONTAL BOUNDARY ON WEDNESDAY...AND FLOODING MAY LAST FOR SEVERAL DAYS OR MORE. && .NEAR TERM /TONIGHT/... ISSUED AT 337 PM EST TUE JAN 29 2013 FOCUS OF THE NEAR TERM REMAINS ON SEVERE WEATHER CHANCES AS WELL AS POSSIBLE HEAVY RAINFALL/FLOODING POSSIBILITIES TONIGHT. THE PERIOD BEGINS WITH GOOD SHORT TERM MODEL AGREEMENT AS TO THE LOCATION OF KEY FEATURES THAT MAY BRING POSSIBLE SEVERE TO PORTIONS OF THE FORECAST AREA TONIGHT. AT 00Z/WED...THE LOW PRESSURE CENTER IS PROGGED TO BE OVER CENTRAL MISSOURI...WITH ONGOING CONVECTION POSSIBLY ALREADY IN THE FORM OF A SQUALL LINE ALONG A STRONG COLD FRONT STRETCHED FROM NORTHWEST ILLINOIS...DOWN THROUGH CENTRAL MISSOURI...INTO EASTERN OKLAHOMA/WESTERN ARKANSAS. THERE DOES APPEAR TO BE SOME DIFFERENCES IN SPEED/TIMING OF THE FRONT INTO THE FORECAST AREA...WITH THE HRRR AND RAP INTO THE AREA A BIT QUICKER THE THE NAM AND GFS. PERSONAL EXPERIENCE HAS SHOWN THAT THESE COLD FRONT/SQUALL LINE FEATURES TEND TO COME IN A BIT QUICKER THAN SOMETIMES EXPECTED. THEREFORE...DECIDED TO TREND TOWARD THE HRRR/RUC SOLNS. AS WAS MENTIONED IN PREVIOUS DISCUSSIONS...DYNAMICS WILL NOT BE AN ISSUE WITH THIS SYSTEM AS THE FRONT APPROACHES. A LOW LEVEL JET AOA 80 KTS AT 850 MB IS EXPECTED TO DEVELOP OUT AHEAD OF THE FRONT THIS EVENING AND WILL TRANSLATE INTO OUR AREA TONIGHT. WITH 50 KT WINDS LOCATED APPROXIMATELY 1000-1500 FEET ABOVE THE SURFACE TONIGHT...DAMAGING WINDS MAY BECOME A REAL THREAT WITH ANY STORMS THAT ARE ABLE TO REMAIN ORGANIZED AS THEY PUSH INTO THE FORECAST AREA. ONE LIMITING FACTOR FOR CONVECTION REMAINING ORGANIZED INTO THE OVERNIGHT HOURS IS INSTABILITY. SFC-BASED CAPE LOOKS TO BE IN THE UNDER 200 J/KG RANGE...WHILE MUCAPE GIVES SLIGHTLY HIGHER VALUES OF 200-400 J/KG AS THE FRONT MOVES INTO THE AREA. WITH THE STRONG DYNAMICS AVAILABLE...WILL CONTINUE DAMAGING WINDS REFERENCE IN THE GRIDS. ALSO KEEP IN MIND THAT WITH AMPLE LOW LEVEL SHEAR...0-1 HELICITIES AOA 400-500 M2/S2...AN ISOLATED TORNADO CANNOT BE RULED OUT. THE BEST TIMING FOR SEVERE LOOKS TO START AT APPROXIMATELY 04-05Z ACROSS WESTERN PORTIONS OF THE FORECAST AREA...TO ABOUT 10-11Z OVER THE EAST. JUST ONE OTHER NOTE TO MENTION...THE HRRR ILLUSTRATES A LINE OF CONVECTION DEVELOPING OUT AHEAD OF THE MAIN SQUALL LINE. TO A LESSER EXTENT...THE RAP ALSO DEPICTS A SIMILAR SCENARIO. WHILE THIS FORECAST HAS TAKEN THIS INTO CONSIDERATION...IT COULD STILL ALLOW FOR AN EARLIER ONSET THAN FORECAST. HEAVY RAINFALL IS ALSO IN PLAY TONIGHT AS MOISTURE HAS CONTINUED TO STREAM NORTH INTO THE AREA. A PACIFIC TROPICAL PLUME OF MOISTURE HAS BEEN EVIDENT ALL DAY ON WATER VAPOR IMAGERY STREAMING NORTHWEST INTO LOWER MISSOURI/MID MISSISSIPPI/OHIO RIVER VALLEY STATES. COUPLE THAT WITH 60 DEGREE DEWPOINTS CURRENTLY ON THE SOUTHWESTERN DOORSTEP OF THE FORECAST AREA. PWATS TONIGHT AHEAD OF THE FRONT LOOK TO REACH UPWARDS OF 1.40-1.50 INCHES...YIELDING A PERCENT OF NORMAL OF AROUND 300 PERCENT. WOULD NOT BE SURPRISED TO SEE A WIDESPREAD 1 TO 1.5 INCH RAINFALL...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... ISSUED AT 337 PM EST TUE JAN 29 2013 SHORT TERM PERIOD SEES A DIFFERENT SET OF CHALLENGES. ONE OF THE INITIAL CHALLENGES WILL BE STRONG WINDS AFTER THE COLD FRONT SWEEPS THROUGH THE AREA AND A DRY SLOT APPROACHES THE FORECAST AREA DURING THE AFTERNOON HOURS. SUSTAINED WINDS AROUND 20-25 KTS...WITH THE POSSIBILITY TO TAP 40 KT WINDS FROM APPROX 850 MB AS BOUNDARY LAYER MIXES OUT. A WIND ADVISORY MAY BE NEED FOR A TIME IN THE LATE MORNING TO EARLY EVENING HOURS ON WEDNESDAY. ADDITIONALLY...SOME LIGHT SNOW SHOWERS MAY WRAP AROUND AND AFFECT MAINLY NORTHERN PORTIONS OF THE FORECAST AREA WEDNESDAY NIGHT AS THE UPPER TROUGH FINALLY PASSES THROUGH. NOT CURRENTLY EXPECTING MUCH IN THE WAY OF ACCUMULATION. ANOTHER UPPER TROUGH AND COLD FRONT PUSHES INTO THE THROUGH THE AREA LATE THURSDAY INTO THURSDAY NIGHT...BRINGING AN ADDITIONAL CHANCE FOR SNOW AND FALLING TEMPS. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ISSUED AT 144 PM EST TUE JAN 29 2013 .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE EXTENDED PERIOD WILL NOT BE NEARLY AS ACTIVE AS THE FIRST FEW DAYS OF THE FORECAST. FIRST OFF A SHORT WAVE TROUGH MOVING THROUGH THE GREAT LAKES REGION MAY BRING A FEW SNOW SHOWERS TO CENTRAL INDIANA AT THE BEGINNING OF THIS PERIOD. TEMPS/THICKNESS ALL LOOK COLD ENOUGH FOR PLAIN SNOW DURING THIS TIME. ATTM ACCUMULATIONS APPEAR TO BE AN INCH OR LESS. AFTER A COLD SHOT OF AIR THU AND FRIDAY...TEMPERATURES WILL GRADUALLY MODERATE TO CLIMO OVER THE WEEKEND AND INTO NEXT WEEK. SECOND HALF OF THE WEEKEND LOOKS DRY AND INTO EARLY NEXT WEEK. ENSEMBLES SHOW SOME PRECIP BY NEXT MONDAY/MONDAY NIGHT. TEMPERATURES LOOK WARM ENOUGH FOR A SNOW/RAIN MIX ACROSS A GOOD PORTION OF THE AREA. HAVE SMALL MINIMAL PRECIP CHANCES IN DURING THIS TIME. && .AVIATION /DISCUSSION FOR THE 30/00Z TAF ISSUANCE/... ISSUED AT 610 PM EST TUE JAN 29 2013 POTENT SPRING-LIKE WEATHER SYSTEM IS EXPECTED TO BRING STRONG TO SEVERE THUNDERSTORMS TO CENTRAL INDIANA LATE THIS EVENING AND EARLY OVERNIGHT. THE RAPID REFRESH REFLECTIVITY PROGS AND AWIPS-DISTANCE SPEED TOOL SUGGEST A LINE OF STORMS SHOULD REACH HUF AND LAF AROUND 04Z AND IND AND BMG AROUND 06Z WITH PLENTY OF TRAILING RAIN. BASED ON LIGHTNING DATA AND EXPECTED TIMING...WENT WITH IFR TEMPO THUNDERSTORM GROUP AS THE ACTIVITY REACHES THE TERMINALS ALONG WITH SOUTHWEST WINDS TO 30 KNOTS AND WIND GUSTS TO 40 KNOTS. HIGHER GUSTS ARE POSSIBLE WITH THE AREA IN A SLIGHT RISK TONIGHT...SO MAY NEED TO EVENTUALLY UP THOSE GUSTS TO SEVERE CRITERIA. FLIGHT CONDITIONS WILL START AS MVFR AND COULD DROP TO IFR OVERNIGHT BEFORE COMING UP TO VFR BY TOMORROW AFTERNOON BEHIND THE FRONTAL SYSTEM. WOULD NOT RULE OUT A FEW RAIN SHOWERS TOMORROW AFTERNOON EVEN MIXING WITH SNOW...BUT COVERAGE SHOULD BE ON THE LOW SIDE...SO LEFT THEM OUT FOR NOW. BASED ON VWP PROFILE DATA ALONG WITH BUFKIT...MOVED THE LOW LEVEL WIND SHEAR UP A FEW HOURS. WINDS SHOULD STAY UP TOMORROW WITH GUSTS TO 30 KNOTS OR MORE WITH DIRECTION SHIFTING TO WEST BEHIND THE FRONTAL SYSTEM. && .IND WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH FROM 7 PM EST THIS EVENING THROUGH WEDNESDAY MORNING FOR INZ021-028>031-035>049-051>057-060>065-067>072. && $$ SYNOPSIS...MRD NEAR TERM...MRD SHORT TERM...MRD LONG TERM....SMF AVIATION...MK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
912 PM CST TUE JAN 29 2013 .UPDATE... THERE WILL BE LITTLE CHANGE IN THINKING WITH A TOKEN EVENING UPDATE TO FIT CURRENT OBS. WAS ORIGINALLY THINKING THAT FORECAST AMOUNTS MAY BE TOO HIGH ON NW FRINGE OF FORECAST PRECIP SHIELD...HOWEVER 00Z NAM IS NOW PLACING HEAVIEST SNOWFALL AXIS SW-NE RIGHT THROUGH DES MOINES. FAR NW FRINGE OF ADVISORY MAY BE OVERDONE...BUT STILL LOOKS LIKE FORT DODGE AND MASON CITY AREAS MAY BE BRUSHED...ESPECIALLY SRN PORTIONS OF THOSE COUNTIES. NO CHANGES IN HEADLINES WHICH CONFIDENCE IN ANY PARTICULAR SOLUTION NOT GREAT ENOUGH TO CHANGE THINGS. LOOKED TO THE RAP FOR GUIDANCE BUT PAST SEVERAL RUNS ARE LITTLE HELP AS THEY HAVE BEEN CONSISTENTLY TOO AGGRESSIVE IN TIMING AND STRENGTH WITH PRECIP ONSET INTO IA. 00Z H85 ANALYSIS SHOWS STRONG WARM/MOIST ADVECTION INTO ST JOESPH/KC METRO AREAS AND TOPS ARE COOLING THERE SO SEE LITTLE REASON TO DOUBT PREVIOUS THINKING WITH PRECIP BLOSSOMING SHORTLY AND THAT APPEARS TO BE THE CASE. RADAR ECHOES ARE STRENGTHENING AND VIRGA DONUT SHRINKING. DUAL POL RADAR PRODUCTS SHOW RAIN/SNOW LINE ROUGHLY ALONG BEDFORD-OSCEOLA-NEWTON LINE SO SHOULD SEE ONLY SNOW TO N AND W OF THESE AREAS. PREVIOUS 00Z UPDATE...ADJUSTED FORECAST AND HEADLINES TO NOT START UNTIL 03Z BASED ON LATEST MODEL GUIDANCE AND OBSERVATIONAL TRENDS. WILL OBVIOUSLY RE-EXAMINE FORECAST FURTHER AFTER 00Z MODELS COME IN AND SYSTEM STARTS TO SHOW ITS HAND MORE UPSTREAM INTO NE AND KS. ADDED 00Z TAF DISCUSSION. && .SHORT TERM /TONIGHT/... UPPER WAVE EVIDENT ON WATER VAPOR DIGGING ALONG THE US/MEXICO BORDER AND STARTING TO LIFT NORTHEASTWARD INTO THE TEX PANHANDLE...TO CONTINUE ITS CURRENT TRAJECTORY NORTHEASTWARD THROUGH THE CENTRAL PLAINS AND INTO THE MID MISSISSIPPI VALLEY BY EARLY WEDNESDAY. THE STATE BECOMES SANDWICHED BETWEEN COUPLED JET STREAKS ALOFT...WITH STRONGEST FRONTOGENETICAL LIFT SHOWING UP ACROSS THE SOUTHEASTERN HALF OF THE CWA LATE THIS EVENING INTO THE OVERNIGHT HOURS. TROWAL FEATURE TO ROTATE EASTWARD THROUGH CENTRAL/SOUTHEASTERN CWA...WITH INCREASING MOISTURE IN THE LOW/MID LEVELS. DRIER AIR WORKING ITS WAY INTO THE NORTH SHOULD YIELD A SHARP CUTOFF IN THE SNOW FIELD TO THE NORTHWEST...WITH THE NORTHWESTERN CUTOFF TO THE HEAVIER SNOW FROM NEAR CORNING NORTHEASTWARD TO WAVERLY. HEAVIEST AMOUNTS EXPECTED ACROSS THE FAR SOUTHEASTERN CWA...WHERE QPF WILL BE GREATER AND COULD SEE SOME WEAK INSTABILITY ALOFT ENHANCE SNOWFALL RATES AT TIMES LATE TONIGHT. OVERALL THREE TO FOUR INCHES OF SNOW EXPECTED TO FALL ACROSS THE SOUTHEASTERN HALF OF THE CWA BY 12Z WEDNESDAY. SFC PRES GRADIENT TO TIGHTEN ON THE BACKSIDE OF THIS SYSTEM...WITH STRONG CAA. 925MB TO 850MB WINDS EXPECTED TO BE IN THE 30 TO 35KT RANGE BY LATE TONIGHT...WITH THESE WINDS TRANSLATING TO THE SURFACE WITH THE STRONG CAA. THEREFORE EXPECTING SUSTAINED WINDS IN THE 20 TO 30 MPH RANGE...WITH GUSTS TO 35 MPH OR HIGHER BY LATE TONIGHT ACROSS THE AREA. THIS WILL LEAD TO CONSIDERABLE BLOWING SNOW IN OPEN AREAS. ADDITIONALLY WITH THE RESIDUAL SURFACE MOISTURE AROUND...AND POSSIBILITY OF HEAVY WET SNOW INITIALLY BEFORE THE DRIER AIR WORKS INTO THE AREA RESULTING IN A LIGHTER FLUFFIER SNOW...SOME ICING MAY OCCUR ON ROADWAYS...TREES BRANCHES...AND POWER LINES. THEREFORE WILL CONTINUE THE WINTER HEADLINES AS THEY ARE FOR TONIGHT INTO WEDNESDAY MORNING. .LONG TERM /WEDNESDAY THROUGH TUESDAY/... RAPIDLY DEEPENING LOW PRESSURE WILL BE OVER CENTRAL ILLINOIS BY 12Z AND WILL SHIFT NORTHEAST INTO LOWER MICHIGAN BY 18Z. PV ANOMALY CURRENTLY OVER WEST CENTRAL TEXAS WILL BE ENTERING SOUTHEAST IOWA AS WELL BY 12Z WITH STRONG QG FORCING CONTINUING THROUGH MID TO LATE MORNING OVER THE SOUTHEAST. A PORTION OF THE WARM CONVEYOR WILL CONTINUE TO SUPPLY MOISTURE INTO THE SOUTHEAST EARLY IN THE PERIOD BEFORE DRIER AIR ADVECTS IN BY MID TO LATE MORNING. BEST SNOW ACCUMULATIONS WILL OCCUR THROUGH 15Z THEN DIMINISHING AFTER THAT TIME. THE MOST DIFFICULT PORTION OF THE SNOW FORECAST REMAINS THE NORTHWEST EDGE. ANY SHIFT SOUTHEAST OF THE STORM TRACK WOULD REDUCE SNOWFALL AMOUNT IN THESE REGIONS. THE STRONG WIND POTENTIAL WITH THIS SYSTEM WEDNESDAY MORNING REMAINS HIGH. IN ADDITION TO A TIGHT PRESSURE GRADIENT OF 30 TO 40 UBARS/KM...THE STRONG COLD ADVECTION WILL KEEP WINDS MIXED UP TO 900 MB WITH 35 TO 40 KTS AVAILABLE IN THAT MIXED LAYER. THE COLD ADVECTION WILL LEAD TO GOOD MOMENTUM TRANSFER OF THE WINDS WITH STRONGEST WINDS OCCURRING 12-18Z. AREAS WITH 2-3 INCHES OF SNOW OR MORE WILL HAVE SIGNIFICANT BLOWING SNOW WEDNESDAY MORNING THAT COULD APPROACH BLIZZARD CRITERIA. IN ADDITION...WITH WARMER NEAR SFC TEMPERATURES...THE SNOW FALL COULD HAVE SIMILAR PROPERTIES TO THAT OF THE DECEMBER BLIZZARD INITIALLY IN THAT IT WILL MELT THEN FREEZE UNDER THE FALLING SNOW RESULTING IN AN ICY SUB LAYER. THIS WOULD MAKE TRAVEL EXTREMELY HAZARDOUS THROUGH THIS EVENT. THE ACCUMULATING SNOW WILL END BY NOON WITH STEADY OR FALLING TEMPERATURES THE REMAINDER OF THE DAY. TEMPERATURES WILL BE COLD WEDNESDAY NIGHT WITH LOWS BELOW ZERO NORTH THOUGH LINGERING CLOUDS COULD HOLD TEMPERATURES UP OVERALL. ANOTHER UPPER WAVE WILL PUSH THROUGH WEDNESDAY NIGHT AND THURSDAY MORNING WITH AN ARCTIC BOUNDARY MOVING THROUGH THURSDAY AS WELL. WIND CHILL VALUES BY WEDNESDAY NIGHT AND THURSDAY WILL APPROACH 25 BELOW OVER NORTHERN IOWA DURING THIS PERIOD. CURRENTLY HAVE FLURRIES IN THE FORECAST FOR THURSDAY BUT THIS WILL NEED TO BE REEVALUATED FOR POTENTIAL OF VERY LIGHT SNOWFALL WITH A BRIEF PERIOD OF SATURATION AND LIFT THROUGH THE DENDRITIC LAYER. ARCTIC HIGH PRESSURE WILL DROP SOUTHEAST INTO THE STATE THURSDAY NIGHT. OVERNIGHT LOW TEMPERATURE WELL BELOW ZERO ARE EXPECTED. POSSIBLE TO BE WELL BELOW GUIDANCE WHERE THE NEW SNOW PACK IS. ANOTHER UPPER LEVEL SYSTEM WILL FOLLOW THE HIGH PRESSURE DEPARTURE BY FRIDAY AFTERNOON. ANOTHER PERIOD OF VERY LIGHT SNOW MAY OCCUR WITH THE SYSTEM PASSAGE. GRADUAL WARMING INTO THE WEEKEND WITH TEMPERATURES PUSHING INTO THE 20S AND 30S. THE NEXT UPPER WAVE DROPPING THROUGH NORTHWEST FLOW WILL ARRIVE MONDAY AND WILL DROP ANOTHER PUSH OF COLD AIR INTO THE STATE. THE COLD AIR WILL BE SHORT LIVED WITH RIDGING BUILDING INTO FROM THE WEST BY TUESDAY. && .AVIATION...30/00Z MVFR/IFR CIGS IN PLACE ACROSS MUCH OF FORECAST AREA AND CONDITIONS ARE EXPECTED TO WORSEN LATER TONIGHT AS UPSTREAM KS/NE PRECIP EXPANDS AS IT REACHES IA OVERNIGHT. CONDITIONS SHOULD DETERIORATE TO IFR/LIFR BY MIDNIGHT OVER SE HALF OF STATE MAINLY AFFECTING KALO/KDSM/KOTM TAF SITES. NW WINDS WILL CONTINUE TO INCREASE...AND WITH MOD/HEAVY SNOW DEVELOPING BY EARLY WED MORNING...EXPECT SIGNIFICANT REDUCTIONS IN VSBY DUE TO SNOW AND BLOWING SNOW BY THAT TIME. NW WINDS WILL REMAIN STRONG INTO WED WITH SOME GUSTS OVER 30KTS...BUT VSBYS SHOULD IMPROVE LATER IN THE DAY. && .DMX WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING FROM 9 PM THIS EVENING TO NOON CST WED ADAIR-ADAMS-BLACK HAWK-BOONE-BREMER-BUTLER-CLARKE-DALLAS-DECATUR- GRUNDY-HARDIN-JASPER-MADISON-MARSHALL-POLK-RINGGOLD-STORY-TAMA- TAYLOR-UNION-WARREN-APPANOOSE-DAVIS-LUCAS-MAHASKA-MARION-MONROE- POWESHIEK-WAPELLO-WAYNE WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO NOON CST WED AUDUBON-CARROLL-CASS-CERRO GORDO-FRANKLIN-GREENE-GUTHRIE-HAMILTON- WEBSTER-WRIGHT && $$ UPDATE/AVIATION...SMALL SHORT TERM...BEERENDS LONG TERM...DONAVON
AREA FORECAST DISCUSSION
NWS DES MOINES IA
120 AM CST MON JAN 28 2013 ...UPDATED AVIATION DISCUSSION... .UPDATE... DENSE FOG HAS DEVELOPED ACROSS MUCH OF THE CWA...ESPECIALLY AREAS WHICH RECEIVED PRECIPITATION SUNDAY. WHILE AREAS ACROSS THE SOUTH NEAR BOUNDARY AREA NOT EXPERIENCING WIDESPREAD DENSE FOG...EXPECT FOG TO DEVELOP OVERNIGHT AS MOISTURE INCREASES AND WINDS DECREASE. HAVE EXPANDED DENSE FOG ADVISORY TO INCLUDE ENTIRE CWA THROUGH 15Z MONDAY MORNING. AREAS OF DENSE FOG IN SOME COUNTIES MAY BE PATCHY. IN ADDITION...ACROSS THE NORTH WITH TEMPERATURES NEAR OR BELOW FREEZING...COULD SEE REFREEZING OF ROADWAYS OR FOG DEPOSITS ON ROADWAYS CREATING DANGEROUS TRAVEL CONDITIONS. .SHORT TERM /TONIGHT/... UPPER LEVEL FORCING CONTINUES TO WANE WITH DEPARTING KINEMATIC AND THERMODYNAMIC FORCING AS SHORT WAVE CROSSES SRN MN/WI BORDER. POCKET OF WEAK INSTABILITY WITH A FEW HUNDRED MUCAPES IS ALSO EXITING INTO IL. THIS HAD ENDED OUR THREAT OF SHOWERS AND SUBSTANTIAL PRECIP. HOWEVER WEAK FORCING AND CERTAINLY MOISTURE LINGERS 2KM AND BELOW AND WILL RESULT IN PERSISTENT DRIZZLE OR FREEZING DRIZZLE. THIS SENSIBLE WEATHER IS DEPICTED NICELY BY THE LOW LEVEL RAP 285-295K ISENT LAYER WHICH SHOWS MODERATE MOISTURE TRANSPORT AND LIFT THROUGH THE EVENING. THIS WILL ALSO KEEP LOW CLOUDS AND FOG LOCKED IN PLACE. FOG MAY BE DENSE AT TIMES...BUT CONFIDENCE IN WIDESPREAD 1/4SM OR LESS VSBYS IS NOT GREAT ENOUGH TO HEADLINE QUITE YET WITH MOISTURE TRANSPORT ENDING LATE AND LITTLE RADIATIONAL COOLING. ALTHOUGH ONLY TOKEN ADDITIONAL ICE ACCUMULATIONS ARE ANTICIPATED...HAVE LEFT HEADLINES UNCHANGED NORTH. LITTLE IMPROVEMENT IS ANTICIPATED THERE WITH TEMPS HOVERING AROUND 32F ALONG WITH THE DRIZZLE AND FOG. ADVISORY CANCELED FARTHER SOUTH WHERE TEMPS SHOULD REMAIN ABOVE FREEZING. .LONG TERM /MONDAY THROUGH SUNDAY/... FAIRLY ACTIVE MID/LONG RANGE ACROSS THE AREA WITH MAJOR FOCUS ON MONDAY INTO TUESDAY. LARGE UPPER LEVEL TROUGH THAT HAS BEEN SLOWLY PROGRESSING THROUGH THE INTERMOUNTAIN WEST...WILL CONTINUE TO TRANSLATE EASTWARD ACROSS THE CENTRAL PLAINS INTO THE OHIO VALLEY THROUGH WEDNESDAY. INITIALLY THE STATE WILL REMAIN IN SOUTHWEST FLOW ALOFT...WITH CONTINUE LOW LEVEL MOISTURE PUMPING NORTHWARD FROM THE GULF OF MEXICO. SFC LOW PRESSURE DEVELOPING IN LEE OF THE ROCKIES...BEGINS TO SHIFT EAST AND ELONGATE INTO CENTRAL KS/SC NEBRASKA TOWARD MONDAY AFTERNOON. AN ASSOCIATED WARM FRONT WILL LIFT NORTHWARD THROUGH THE STATE LATE MONDAY INTO MONDAY NIGHT. MOISTURE OVERRUNNING THE AREA TO THE NORTH OF THIS WARM FRONT WILL LEAD TO LOW STRATUS AND FOG LINGERING ACROSS THE CWA MONDAY. ISENTROPIC LIFT EVIDENT ON THE 285K TO 290K SURFACES BEGINS TO SHOW UP ACROSS THE SOUTHERN CWA BY LATE MONDAY MORNING WITH LIFT SPREADING NORTHWARD INTO THE AFTERNOON HOURS. THIS WILL BRING THE CHANCE FOR DRIZZLE OR LIGHT RAIN TO MUCH OF THE SOUTHERN HALF OF IOWA BY MONDAY AFTERNOON IN ADDITION TO THE LOW CLOUDS/FOG. VISIBILITIES EXPECTED TO BE QUITE LOW WITH THE FOG THROUGHOUT THE MORNING HOURS...WITH SOME IMPROVEMENT IN THE AFTERNOON. POSSIBILITY OF NEEDING A DENSE FOG ADVISORY FOR THE MORNING HOURS...BUT WILL NOT ISSUE NOW DUE TO WINTER HEADLINES ALREADY IN EFFECT FOR SIMPLICITY. GREATER PUSH OF MOISTURE...WITH DEEPER SATURATION EXPECTED AND CONTINUE WAA INTO MONDAY NIGHT AS WARM FRONT LIFTS NORTHWARD THROUGH THE STATE. HAVE A NON-DIURNAL TEMPERATURE TREND MONDAY NIGHT AS AREAS EXPECTED TO WARM OR REMAIN STEADY BEHIND THE WARM FRONT. FOG COULD CONTINUE TO BE AN ISSUE INTO MONDAY NIGHT WITH ABUNDANT LOW LEVEL MOISTURE. ADDITIONALLY NAM/GFS BOTH ADVERTISE SOME ELEVATED INSTABILITY SPREADING NORTHWARD INTO THE CWA...WITH THE NAM MOST AGGRESSIVE. THEREFORE CONTINUED THE THUNDER MENTION ACROSS THE SOUTHERN HALF/EASTERN HALF OF THE CWA. AS THE SFC LOW LIFTS NORTHEASTWARD THROUGH THE STATE INTO TUESDAY MORNING...ASSOCIATED COLD FRONT TO PUSH THROUGH CWA TUESDAY. THIS WILL LEAD TO PRECIPITATION TRANSITIONING TO A MIX OF RAIN/SNOW TO ALL SNOW/FLURRIES ACROSS THE NORTHERN CWA BEFORE PRECIPITATION TAPERS OFF LATER THAT DAY. POSSIBILITY STILL EXISTS THAT COULD SEE A MIX OF FREEZING RAIN AS WELL...AS DEPENDS ON HOW DEEP SATURATION IS AND IF ICE CAN BE INTRODUCED INTO THE COLUMN. CURRENT NAM SOUNDINGS SUGGEST DEEP ENOUGH SATURATION WITH ICE INTRODUCED WHICH WOULD ALLOW FOR SNOW...WHILE GFS SUGGEST DRIER AIR ALOFT WITH NO ICE INTRODUCTION LEADING TO RAIN/FZRA/FZDZ DEPENDING ON SURFACE TEMPS. FOR NOW HAVE TRENDED FORECAST TOWARD THE NAM SOLUTION. BROAD UPPER LEVEL TROUGH THEN REMAINS ACROSS THE EASTERN US...WITH NORTHWESTERLY FLOW ALOFT FOR THE REMAINDER OF THE PERIOD. THIS WILL ALLOW FOR A SERIES OF WEAK SHORTWAVES TO TRAVEL THROUGH THE MAIN UPPER LEVEL TROUGH AND DROP SOUTH THROUGH THE CWA. THIS WILL BRING CONTINUED PUSHES OF ARCTIC AIR FOR LATE THIS WEEK INTO THE WEEKEND...WITH H85 TEMPS DROPPING INTO THE NEGATIVE TEENS TO 20S CELSIUS. THIS WILL SEND TEMPERATURES TO BELOW AVERAGE BY THE END OF THE WEEK INTO THE WEEKEND. WITH EACH WAVE PASSAGE...SOME FLURRIES OR LIGHT SNOW MAY BE POSSIBLE BUT HAVE LEFT THE FORECAST MAINLY DRY FOR NOW WITH THE UNCERTAINTY IN THE TIMING OF EACH IMPULSE. BROAD UPPER LEVEL RIDGING BEGINS TO NUDGE INTO THE CENTRAL US TOWARD THE END OF THE WEEKEND INTO EARLY NEXT WEEK...SUGGESTING A WARMING TREND AS H85 TEMPS CLIMB BACK ABOVE FREEZING. && .AVIATION...28/06Z NO MAJOR CHANGES FROM PREVIOUS FORECAST AS CONFIDENCE IS HIGH WITH LIFR/IFR CONDITIONS THROUGH THE CRITICAL TAF PERIOD AND INTO MONDAY MORNING. CIGS LOOK TO REMAIN BELOW 500 FEET AND VIS WILL BOUNCE AROUND BELOW 1SM. CURRENT DRIZZLE WILL COME TO AN END BY AROUND 08Z AT ALO/OTM...AND A BIT SOONER AT DSM. CIGS/VIS MAY IMPROVE TO MVFR LATE MONDAY MORNING INTO THE AFTERNOON HOURS...BUT ANTICIPATED TO REDEVELOP MONDAY NIGHT. HAVE INTRODUCED IFR/LIFR CONDITIONS PAST 00Z TUESDAY. && .DMX WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY IN EFFECT UNTIL 9 AM CST MONDAY MORNING FOR ALL OF CENTRAL IOWA. && $$ SHORT TERM...SMALL LONG TERM...BEERENDS AVIATION...PODRAZIK UPDATE...AWB
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1155 PM CST SUN JAN 27 2013 ...UPDATED AVIATION DISCUSSION... .SHORT TERM /TONIGHT/... UPPER LEVEL FORCING CONTINUES TO WANE WITH DEPARTING KINEMATIC AND THERMODYNAMIC FORCING AS SHORT WAVE CROSSES SRN MN/WI BORDER. POCKET OF WEAK INSTABILITY WITH A FEW HUNDRED MUCAPES IS ALSO EXITING INTO IL. THIS HAD ENDED OUR THREAT OF SHOWERS AND SUBSTANTIAL PRECIP. HOWEVER WEAK FORCING AND CERTAINLY MOISTURE LINGERS 2KM AND BELOW AND WILL RESULT IN PERSISTENT DRIZZLE OR FREEZING DRIZZLE. THIS SENSIBLE WEATHER IS DEPICTED NICELY BY THE LOW LEVEL RAP 285-295K ISENT LAYER WHICH SHOWS MODERATE MOISTURE TRANSPORT AND LIFT THROUGH THE EVENING. THIS WILL ALSO KEEP LOW CLOUDS AND FOG LOCKED IN PLACE. FOG MAY BE DENSE AT TIMES...BUT CONFIDENCE IN WIDESPREAD 1/4SM OR LESS VSBYS IS NOT GREAT ENOUGH TO HEADLINE QUITE YET WITH MOISTURE TRANSPORT ENDING LATE AND LITTLE RADIATIONAL COOLING. ALTHOUGH ONLY TOKEN ADDITIONAL ICE ACCUMULATIONS ARE ANTICIPATED...HAVE LEFT HEADLINES UNCHANGED NORTH. LITTLE IMPROVEMENT IS ANTICIPATED THERE WITH TEMPS HOVERING AROUND 32F ALONG WITH THE DRIZZLE AND FOG. ADVISORY CANCELED FARTHER SOUTH WHERE TEMPS SHOULD REMAIN ABOVE FREEZING. .LONG TERM /MONDAY THROUGH SUNDAY/... FAIRLY ACTIVE MID/LONG RANGE ACROSS THE AREA WITH MAJOR FOCUS ON MONDAY INTO TUESDAY. LARGE UPPER LEVEL TROUGH THAT HAS BEEN SLOWLY PROGRESSING THROUGH THE INTERMOUNTAIN WEST...WILL CONTINUE TO TRANSLATE EASTWARD ACROSS THE CENTRAL PLAINS INTO THE OHIO VALLEY THROUGH WEDNESDAY. INITIALLY THE STATE WILL REMAIN IN SOUTHWEST FLOW ALOFT...WITH CONTINUE LOW LEVEL MOISTURE PUMPING NORTHWARD FROM THE GULF OF MEXICO. SFC LOW PRESSURE DEVELOPING IN LEE OF THE ROCKIES...BEGINS TO SHIFT EAST AND ELONGATE INTO CENTRAL KS/SC NEBRASKA TOWARD MONDAY AFTERNOON. AN ASSOCIATED WARM FRONT WILL LIFT NORTHWARD THROUGH THE STATE LATE MONDAY INTO MONDAY NIGHT. MOISTURE OVERRUNNING THE AREA TO THE NORTH OF THIS WARM FRONT WILL LEAD TO LOW STRATUS AND FOG LINGERING ACROSS THE CWA MONDAY. ISENTROPIC LIFT EVIDENT ON THE 285K TO 290K SURFACES BEGINS TO SHOW UP ACROSS THE SOUTHERN CWA BY LATE MONDAY MORNING WITH LIFT SPREADING NORTHWARD INTO THE AFTERNOON HOURS. THIS WILL BRING THE CHANCE FOR DRIZZLE OR LIGHT RAIN TO MUCH OF THE SOUTHERN HALF OF IOWA BY MONDAY AFTERNOON IN ADDITION TO THE LOW CLOUDS/FOG. VISIBILITIES EXPECTED TO BE QUITE LOW WITH THE FOG THROUGHOUT THE MORNING HOURS...WITH SOME IMPROVEMENT IN THE AFTERNOON. POSSIBILITY OF NEEDING A DENSE FOG ADVISORY FOR THE MORNING HOURS...BUT WILL NOT ISSUE NOW DUE TO WINTER HEADLINES ALREADY IN EFFECT FOR SIMPLICITY. GREATER PUSH OF MOISTURE...WITH DEEPER SATURATION EXPECTED AND CONTINUE WAA INTO MONDAY NIGHT AS WARM FRONT LIFTS NORTHWARD THROUGH THE STATE. HAVE A NON-DIURNAL TEMPERATURE TREND MONDAY NIGHT AS AREAS EXPECTED TO WARM OR REMAIN STEADY BEHIND THE WARM FRONT. FOG COULD CONTINUE TO BE AN ISSUE INTO MONDAY NIGHT WITH ABUNDANT LOW LEVEL MOISTURE. ADDITIONALLY NAM/GFS BOTH ADVERTISE SOME ELEVATED INSTABILITY SPREADING NORTHWARD INTO THE CWA...WITH THE NAM MOST AGGRESSIVE. THEREFORE CONTINUED THE THUNDER MENTION ACROSS THE SOUTHERN HALF/EASTERN HALF OF THE CWA. AS THE SFC LOW LIFTS NORTHEASTWARD THROUGH THE STATE INTO TUESDAY MORNING...ASSOCIATED COLD FRONT TO PUSH THROUGH CWA TUESDAY. THIS WILL LEAD TO PRECIPITATION TRANSITIONING TO A MIX OF RAIN/SNOW TO ALL SNOW/FLURRIES ACROSS THE NORTHERN CWA BEFORE PRECIPITATION TAPERS OFF LATER THAT DAY. POSSIBILITY STILL EXISTS THAT COULD SEE A MIX OF FREEZING RAIN AS WELL...AS DEPENDS ON HOW DEEP SATURATION IS AND IF ICE CAN BE INTRODUCED INTO THE COLUMN. CURRENT NAM SOUNDINGS SUGGEST DEEP ENOUGH SATURATION WITH ICE INTRODUCED WHICH WOULD ALLOW FOR SNOW...WHILE GFS SUGGEST DRIER AIR ALOFT WITH NO ICE INTRODUCTION LEADING TO RAIN/FZRA/FZDZ DEPENDING ON SURFACE TEMPS. FOR NOW HAVE TRENDED FORECAST TOWARD THE NAM SOLUTION. BROAD UPPER LEVEL TROUGH THEN REMAINS ACROSS THE EASTERN US...WITH NORTHWESTERLY FLOW ALOFT FOR THE REMAINDER OF THE PERIOD. THIS WILL ALLOW FOR A SERIES OF WEAK SHORTWAVES TO TRAVEL THROUGH THE MAIN UPPER LEVEL TROUGH AND DROP SOUTH THROUGH THE CWA. THIS WILL BRING CONTINUED PUSHES OF ARCTIC AIR FOR LATE THIS WEEK INTO THE WEEKEND...WITH H85 TEMPS DROPPING INTO THE NEGATIVE TEENS TO 20S CELSIUS. THIS WILL SEND TEMPERATURES TO BELOW AVERAGE BY THE END OF THE WEEK INTO THE WEEKEND. WITH EACH WAVE PASSAGE...SOME FLURRIES OR LIGHT SNOW MAY BE POSSIBLE BUT HAVE LEFT THE FORECAST MAINLY DRY FOR NOW WITH THE UNCERTAINTY IN THE TIMING OF EACH IMPULSE. BROAD UPPER LEVEL RIDGING BEGINS TO NUDGE INTO THE CENTRAL US TOWARD THE END OF THE WEEKEND INTO EARLY NEXT WEEK...SUGGESTING A WARMING TREND AS H85 TEMPS CLIMB BACK ABOVE FREEZING. && .AVIATION...28/06Z NO MAJOR CHANGES FROM PREVIOUS FORECAST AS CONFIDENCE IS HIGH WITH LIFR/IFR CONDITIONS THROUGH THE CRITICAL TAF PERIOD AND INTO MONDAY MORNING. CIGS LOOK TO REMAIN BELOW 500 FEET AND VIS WILL BOUNCE AROUND BELOW 1SM. CURRENT DRIZZLE WILL COME TO AN END BY AROUND 08Z AT ALO/OTM...AND A BIT SOONER AT DSM. CIGS/VIS MAY IMPROVE TO MVFR LATE MONDAY MORNING INTO THE AFTERNOON HOURS...BUT ANTICIPATED TO REDEVELOP MONDAY NIGHT. HAVE INTRODUCED IFR/LIFR CONDITIONS PAST 00Z TUESDAY. && .DMX WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY IN EFFECT UNTIL 9 AM CST MONDAY MORNING FOR ALL OF CENTRAL IOWA EXCEPT FOR PORTIONS OF NORTH CENTRAL IOWA. && $$ SHORT TERM...SMALL LONG TERM...BEERENDS AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS TOPEKA KS
556 PM CST TUE JAN 29 2013 .DISCUSSION... 21Z RAP AND 18Z NAM HAVE STARTED TO SHOW SOME INDICATION OF A DECENT FRONTOGENETICAL BAND DEVELOPING MAINLY DURING THE 06Z TO 12Z TIME FRAME. WITH RECENT RADAR TRENDS SHOWING A BAND STARTING TO FORM ACROSS WESTERN KS...AM BEGINNING TO THINK THAT MODELS ARE DOING A REASONABLE JOB DEPICTING THE SYSTEM AS IT LIFTS OUT OVERNIGHT. CONFIDENCE IS INCREASING THAT THERE WILL BE SNOW. SNOW AMOUNTS SEEM TO BE IN THE BALLPARK INITIALLY. WITH SOME UNCERTAINTY FROM THE PREV FORECAST ABOUT MESOSCALE FORCING...THINK THAT FORECAST SNOW AMOUNTS ARE PROBABLY NOT ON THE LOW SIDE. THERE ARE STILL SOME QUESTIONS WITH SOME INDICATIONS OF MID LEVEL DRY AIR COMING IN AT THE DENDRITIC GROWTH ZONE AND A GENERAL LACK OF INSTABILITY OF CONDITIONAL INSTABILITY THAT COULD ACT TO KEEP SNOW AMOUNT ON WITHIN THE FORECASTED VALUES. IF ANYTHING WILL NEED TO WATCH THINGS PROGRESS AND POTENTIALLY EXPAND THE ADVISORY IF INDEED A BAND OF MODERATE SNOW MOVES ACROSS THE AREA. MODELS CONTINUE TO SHOW A STRENGTHENING PRESSURE GRADIENT WITH NORTH AND NORTHWEST WINDS GUSTING UP TO 35 MPH. WOLTERS && .AVIATION... WITH INCREASING CONFIDENCE IN SNOW MOVING IN FROM THE WEST...THERE IS INCREASED CONFIDENCE IN IFR AND LIFR CONDITIONS FORMING OVERNIGHT. AT THIS TIME...THE BEST GUESS FOR WHEN THE HEAVIER SNOW WILL OCCUR IS BETWEEN 04Z AND 11Z AT THE TERMINALS. BY 15Z THE FORCING LOOKS TO MOVE TO THE EAST OF THE AREA WITH CONDITIONS IMPROVING. WOLTERS && .PREV DISCUSSION... /328 PM CST TUE JAN 29 2013/ THE ABRUPT RETURN TO WINTER CONTINUES TODAY ACROSS THE FORECAST AREA...AFTER A ROUND OF MORNING SHOWERS AND THUNDERSTORMS FOR EASTERN PORTIONS OF THE STATE. THE DEEP LONGWAVE TROF CONTINUES TO MOVE EASTWARD ACROSS THE ROCKY MOUNTAINS AND INTO THE HIGH PLAINS. ENERGY ROTATING THROUGH THE TX PANHANDLES AIDING IN ENHANCING A NEGATIVE TILT TO THE SOUTHERN STREAM AS IT LIFTS INTO OUR AREA THIS EVENING AND OVERNIGHT. HAVE EXPANDED THE WINTER WEATHER ADVISORY BOTH WEST AND SOUTH A FEW COUNTIES. STILL APPEARS AS IF FAR NE COUNTIES WILL GET THE HIGHER SNOW AMOUNTS WHERE BAND OF FRONTOGENESIS TRACKS WEST TO EAST GENERALLY NORTH OF THE INTERSTATE...AS DOES THE MID LEVEL DEFORMATION ZONE. HARD TO SEE A TIME WHEN ALL INGREDIENTS COME TOGETHER FOR A BANDED HEAVY SNOW EVENT...ALTHOUGH AROUND 06Z NORTH OF THE MHK AREA DO SEE SOME FRONTOGENETIC FORCING ALIGNED WITH SOME NEGATIVE EPV...THEREFORE INCREASED SNOW TOTALS FOR THIS AREA. 2-3 INCH LINE RUNS GENERALLY ALONG THE INTERSTATE WITH DIMINISHING AMOUNTS SOUTH AND HIGHER NUMBERS NORTH AND EAST. STARTED ADVISORY WEST AT 6PM FOLLOWED BY AN 11PM START FOR COUNTIES FARTHER EAST. OF CONCERN ARE THE WINDS THAT ACCOMPANY THIS SYSTEM AS THE SNOW FALLS OVERNIGHT AND INTO THE EARLY COMMUTE TOMORROW MORNING. SNOW WILL REDUCE VISIBILITIES AND MAY MAKE ROADS DIFFICULT TO KEEP CLEAR...SO THAT EVEN A FEW INCHES OF SNOW MAY BRING TRAVEL PROBLEMS. SNOW SHOULD END BY 9AM AND WILL LIKELY END A FEW HOURS SOONER OUT WEST AND CAN ADJUST ADVISORY ENDING AS NEEDED. THURSDAY THROUGH NEXT TUESDAY...DRY WEATHER WILL LIKELY CONTINUE THROUGH THE REMAINDER OF THE FORECAST PERIOD AS COLD AND DRY AIR PLUNGES SOUTHWARD INTO THE CENTRAL PLAINS. NORTHWEST FLOW ALOFT ON THE EASTERN EDGE OF A STRONGLY AMPLIFIED RIDGE OVER THE WESTERN CONUS WILL PREVENT THE FORMATION OF ANY STRONG SURFACE TROUGH AND SUBSEQUENT WARM AIR ADVECTION THROUGH THE REST OF THE WORK WEEK. THE FIRST PUSH OF COLD AIR WILL ALSO LIKELY BE REINFORCED BY A SECOND PUSH OF COLD AIR ON THURSDAY NIGHT...WHICH MODELS CURRENTLY PROG TO BE CHARACTERIZED BY 850 MB TEMPERATURES AROUND -15 DEGREES C. THE COLDEST MORNING AT THIS TIME LOOKS TO BE FRIDAY MORNING...WHEN THE SURFACE HIGH ASSOCIATED WITH THE ARCTIC AIRMASS BECOMES CENTERED OVER NORTHEAST KANSAS. CURRENTLY THE FORECAST FOR FRIDAY MORNING REFLECTS SLIGHTLY LOWER TEMPS THAN THE PREVIOUS FORECAST SUGGESTED DUE TO THE FACT THAT SNOW FROM TUESDAY NIGHT/WED MORNING WILL LIKELY LINGER PREVENTING THE POLAR AIR FROM MODIFYING MUCH. GIVEN THAT SNOW WILL LIKELY STILL BE ON THE GROUND AND THAT SKIES WILL CLEAR AND WINDS WILL BE CALM...IN RESPONSE TO THE SURFACE HIGH...EXPECT FRIDAY MORNING TO BE VERY CHILLY...WITH LOWS IN THE SINGLE DIGITS TO LOWER TEENS. BY SATURDAY THE SURFACE HIGH WILL SLIDE EASTWARD AND SOUTHERLY RETURN FLOW WILL COMMENCE ON THE BACKSIDE OF THE HIGH. CONCURRENTLY THE AFOREMENTIONED WESTERN CONUS RIDGE MAY SHIFT EVER SO SLIGHTLY TO THE EAST...ALLOWING THE COLD AIR ASSOCIATED WITH THE BROAD HUDSON BAY LOW TO ALSO SHIFT EAST. THE BOTTOM LINE FOR THE WEEKEND AND INTO NEXT WEEK IS A GRADUAL WARMING TREND AS SURFACE WINDS WILL BE WESTERLY TO SOUTHWESTERLY...WHICH WILL INTRODUCE A SLIGHT DOWNSLOPE COMPONENT...AIDING IN SURFACE TEMP WARMING. AT THIS POINT MAX TEMPS LOOK TO RUN ABOUT 10 DEGREES ABOVE NORMAL FROM SUNDAY THROUGH NEXT TUESDAY...BUT THIS COULD CHANGE A FEW DEGREES EITHER WAY DEPENDING ON HOW FAST THE SNOW MELTS. JL && .TOP WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 11 PM THIS EVENING TO 9 AM CST WEDNESDAY FOR KSZ010>012-023-024-026-039-040. WINTER WEATHER ADVISORY UNTIL 9 AM CST WEDNESDAY FOR KSZ008-009- 020>022. && $$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
520 PM CST TUE JAN 29 2013 ...UPDATED AVIATION DISCUSSION... .SYNOPSIS... ISSUED AT 1131 AM CST TUE JAN 29 2013 A VERY SHARP UPPER TROUGH EXTENDED FROM THE EASTERN MONTANA PLAINS THROUGH THE SOUTHERN ROCKIES THIS MORNING. ON THE EAST SIDE OF THE TROUGH AS AN INTENSE 120KT JET EXTENDING FROM WESTERN MEXICO THROUGH WEST TEXAS AND THE CENTRAL HIGH PLAINS REGION (INCLUDING WESTERN KANSAS). A COLD FRONT AT 850 MB HAD EXTENDED AS FAR SOUTHEAST AS DODGE CITY, AS WAS MARKED BY A TIGHT TEMPERATURE GRADIENT ACROSS SOUTH CENTRAL KANSAS. DEFORMATION ZONE SNOW HAD DEVELOPED ACROSS THE HIGH PLAINS OF COLORADO AND NORTHWEST KANSAS, AS WAS EVIDENT ON REGIONAL RADAR COMPOSITES. METAR OBSERVATIONS AT LHX/LIC/ITR/GLD ALL INDICATED PERSISTENT LIGHT SNOW INTENSITIES. && .SHORT TERM...(THIS EVENING THROUGH TOMORROW) ISSUED AT 245 PM CST TUE JAN 29 2013 THE IMMEDIATE CONCERN WILL BE NOW-CASTING A SNOW EPISODE ACROSS WEST CENTRAL KANSAS AND DETERMINING THE EASTERN EXTENT OF IMPACT. THE SNOW THAT WAS RAPIDLY EXPANDING ACROSS WEST CENTRAL KANSAS IN THE AFTERNOON WAS DISTRIBUTING WEAKLY BANDED CHARACTERISTICS ON RADAR, BUT NOTHING THAT WOULD INDICATE VERY INTENSE SNOW RATES FROM STRONGLY BANDED ZONES. THE LATEST RAPID REFRESH TRENDS ARE NOT AS OPTIMISTIC FOR ACCUMULATING SNOW ACROSS OUR EXTREME SOUTHWEST COUNTIES THAT ARE IN THE WINTER WEATHER ADVISORY, BUT APPEARS TO EXPANDS THE BEST ACCUMULATING SNOWFALL AMOUNTS TO AROUND 2 INCHES FROM GARDEN CITY AND SCOTT CITY , NORTHWARD THROUGH WAKEENEY AND NORTH CENTRAL KANSAS THROUGH LATE EVENING. THIS IS FAIRLY WELL COINCIDENT WITH THE CURRENT WINTER HEADLINE THROUGH THAT REGION AND TIME FRAME. IT IS UNCERTAIN JUST HOW LONG LIGHT SNOW WILL PERSIST ACROSS PORTIONS OF CENTRAL KANSAS THOUGH TONIGHT AND INTO THE OVERNIGHT. HOWEVER, BASED ON THE MODEL RELATIVE HUMIDITY FIELDS, IT IS SAFE TO SAY THAT LOW LEVEL STRATUS WILL LIKELY BE SLOW TO CLEAR FROM WEST TO EAST. THIS WILL BE DUE TO THE COLD AIR UNDER THE UPPER TROUGH ROTATING INTO THE UPPER MIDWEST BY LATE DAY WEDNESDAY. THE DEEP NORTHWEST FLOW WILL AID IN INCREASING SUBSIDENCE THROUGH EARLY WEDNESDAY MORNING. SCATTERED TO BROKEN MID LEVEL CLOUDS ARE STILL LIKELY BY EARLY WEDNESDAY AFTERNOON. THERE IS A LOT OF MODEL CONSENSUS FOR COLDER TEMPERATURES FALLING INTO THE TEENS IN THE WESTERN COUNTIES, WHERE DRIER AIR WILL LIKELY BE LOCATED, NOT TO MENTION POTENTIAL FOR SOME FRESH SNOW ON THE GROUND. CENTRAL KANSAS IS GENERALLY MODELED AS WARMER WITH LOWS ONLY IN THE LOW 20S. AS A RESULT OF THE PATTERN, WEDNESDAY WILL REMAIN LARGELY COLD AND BREEZY. BETTER CHANCES FOR INSOLATION WILL BE FOUND ACROSS THE WESTERN COUNTIES IN THE AFTERNOON. BY CONTRAST. COLD AIR SHOULD BE ENTRENCHED ACROSS CENTRAL NEBRASKA INTO CENTRAL KANSAS. THE GENERAL CONSENSUS IS FOR HIGHS TO ONLY REACH THE LOW TO MID 30`S ACROSS CENTRAL KANSAS, AND TO AROUND 40 DEGREES IN THE WEST. THE SURFACE PRESSURE GRADIENT WILL ALSO SLACKEN DURING THE DAY. AS A RESULT BREEZY NORTHWEST WINDS IN THE MORNING WILL BECOME LIGHT WESTERLY WITH TIME THROUGH THE DAY. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 328 PM CST TUE JAN 29 2013 WEDNESDAY NIGHT THROUGH FRIDAY: DURING THIS PERIOD...A LONGWAVE TROUGH AXIS OVER THE CENTRAL PORTION OF NORTH AMERICA WILL GRADUALLY SHIFT EAST AS AN UPPER LEVEL RIDGE BUILDS EASTWARD ACROSS WESTERN NORTH AMERICA. THE BEGINNING OF THIS TIME PERIOD WILL BE FAIRLY CHALLENGING FROM A TEMPERATURE FORECAST STANDPOINT AS A BRUTALLY COLD ARCTIC AIRMASS PUSHES SOUTH INTO THE NORTHERN GREAT PLAINS. THIS WILL LEAD TO A RATHER UNCERTAIN TEMPERATURE FORECAST FOR THE DAY THURSDAY AS THE LEADING EDGE OF THE ARCTIC AIRMASS WILL BE IMPINGING ON NORTHERN/CENTRAL KANSAS BY MIDDAY. BOTH THE GFS AND ECMWF MODELS ARE IN FAIRLY GOOD AGREEMENT OF THE ARCTIC FRONT EXTENDING FROM FAR NORTHEAST COLORADO INTO CENTRAL KANSAS BY 18Z THURSDAY. BEFORE THE FRONT MOVES IN...TEMPERATURES SHOULD WARM INTO THE UPPER 30S/LOWER 40S NORTHEAST OF A DIGHTON TO LACROSSE LINE...BUT BY EARLY/MID AFTERNOON TEMPERATURES WILL LIKELY BEGIN TO FALL BACK DOWN INTO THE LOWER 30S OR EVEN UPPER 20S (ESPECIALLY IN ELLIS COUNTY). MEANWHILE SOUTH OF THE FRONT THURSDAY...HIGHS SHOULD REACH THE LOWER TO MID 50S...WITH THE MOST LIKELY LOCATION SEEING THESE TEMPERATURES SOUTH AND WEST OF A JOHNSON TO MEADE LINE. WE WILL ONLY SEE A GLANCING BLOW FROM THIS CANADIAN AIRMASS AS THE CENTER OF THE ARCTIC HIGH MOVES TO THE KANSAS-MISSOURI BORDER BY 12Z FRIDAY. LOW TEMPERATURES WILL BE IN THE TEENS ACROSS CENTRAL KANSAS TO THE LOWER/MID 20S ELSEWHERE...WITH A WIND SHIFT BACK TO THE SOUTHEAST BY DAYBREAK FRIDAY. FRIDAY WILL ALSO BE A CHALLENGING TEMPERATURE FORECAST AS THE SURFACE WIND FLOW WILL BE RECIRCULATING MODIFIED COLD AIR AROUND THE WESTERN PERIPHERY OF THE COLD HIGH. THE CHALLENGE LIES IN THE FACT THAT AT THE SAME TIME...ANOTHER SHORTWAVE TROUGH WILL BE APPROACHING THE HIGH PLAINS IN THE NORTHWEST FLOW PATTERN WHICH WILL LEAD TO DOWNSLOPE WESTERLY MOMENTUM IN THE LOWER TROPOSPHERE. AT SOME POINT DURING THE DAY FRIDAY...THIS WESTERLY MOMENTUM WILL MIX DOWN TO THE SURFACE AND A FAIRLY IMPRESSIVE WARM-UP MAY RESULT. HAVE KEPT HIGH TEMPERATURE FORECAST IN THE MID TO UPPER 40S GENERALLY EAST OF HIGHWAY 283...WITH LOWER TO MID 50S EXPECTED ACROSS FAR SOUTHWEST KANSAS WHERE THE PROBABILITY OF WESTERLY MOMENTUM MIXING DOWN TO THE SURFACE IS BEST (LEADING TO WARMER TEMPERATURES). SATURDAY THROUGH TUESDAY: THE MINOR NORTHWEST FLOW SHORTWAVE TROUGH FRIDAY/FRIDAY NIGHT WILL MOVE RAPIDLY SOUTHEAST ACROSS THE PLAINS INTO THE MISSISSIPPI VALLEY WITHOUT MUCH FANFARE AND UPPER RIDGING WILL DEVELOP ACROSS THE ROCKIES AND INTERMOUNTAIN WEST. LEE TROUGH WILL DEVELOP SATURDAY NIGHT INTO SUNDAY AS YET ANOTHER WEAK...LOW AMPLITUDE SHORTWAVE TROUGH MOVES ACROSS THE ROCKIES. QUITE A BIT OF DOWNSLOPE MOMENTUM IN THE 850-700MB LAYER SATURDAY AND SUNDAY WILL LEAD TO WARM SURFACE TEMPERATURES IN THE MID TO UPPER 50S. ANY WIND SHIFT TO THE NORTHWEST DURING THIS TIME FRAME WILL PROVIDE LITTLE OR NO TEMPERATURE FLUCTUATION GIVEN THE DEGREE OF DOWNSLOPE MOMENTUM AND HELPING KEEP THE TRUE CANADIAN/ARCTIC AIRMASS ACROSS THE NORTHEASTERN PLAINS AND UPPER MIDWEST REGION. MEAN RIDGING EARLY NEXT WEEK ACROSS THE INTERMOUNTAIN WEST/ROCKIES WILL KEEP THE SENSIBLE WEATHER ACROSS WESTERN KANSAS MILD AND DRY (TEMPERATURES IN THE UPPER 50S TO PERHAPS LOWER 60S DURING THE AFTERNOON). && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 514 PM CST TUE JAN 29 2013 MID LEVEL FORCING AHEAD OF AN UPPER LEVEL TROUGH CAN BE EXPECTED ACROSS ALL OF WESTERN KANSAS EARLY THIS EVENING. THIS WILL PRODUCE A PERIOD OF SNOW ALONG WITH IFR CEILING AND/OR VISIBILITIES EARLY TONIGHT. LATEST HRRR AND RAP SUGGESTS THIS BAND OF STEADIER PRECIPITATION WILL END AT GCK AROUND 02Z AND HYS/DDC AROUND 05Z. LATEST 18Z BUFR SOUNDINGS INDICATED SOME SUBSIDENCE AND DRIER AIR WILL DEVELOP AFTER MIDNIGHT AS THE UPPER LEVEL TROUGH MOVES INTO CENTRAL KANSAS. MVFR CIGS CAN BE EXPECTED AFTER 03Z WITH VFR CIGS LIKELY AT ALL THREE TAF SITES BY 09Z. GUSTY NORTHWEST WINDS WILL CONTINUE IN THE 15 TO 20 KNOT RANGE OVERNIGHT. && .PRELIMINARY POINT TEMPS/POPS... DDC 21 38 22 48 / 80 0 0 0 GCK 17 38 22 50 / 90 0 0 0 EHA 18 40 25 54 / 70 0 0 0 LBL 19 41 23 56 / 50 0 0 0 HYS 17 34 19 37 / 90 0 0 0 P28 21 39 23 48 / 80 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 9 PM CST /8 PM MST/ THIS EVENING FOR KSZ030-031-043>045-061>063-074-075. && $$ SYNOPSIS...RUSSELL SHORT TERM...RUSSELL LONG TERM...UMSCHEID AVIATION...BURGERT
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1251 PM MST MON JAN 28 2013 .UPDATE... ISSUED AT 1249 PM MST MON JAN 28 2013 REMOVED THOMAS...SHERIDAN AND GRAHAM COUNTIES FROM THE DENSE FOG ADVISORY. WILL PROBABLY BE ABLE TO REMOVE RAWLINS...DECATUR AND NORTON NEXT HOUR. TEMPERATURES ARE WARMING INTO THE 60S OUTSIDE OF THE FOG AREAS. SOUTHWEST WINDS WILL INCREASE TO 20 TO 30 MPH WITH HIGHER GUSTS. IT WILL BE MARGINAL FOR A WIND ADVISORY AND DO NOT PLAN ONE UNLESS WINDS INCREASE MORE. RH VALUES ARE STAYING ABOVE 20 PERCENT SO DO NOT THINK FIRE WEATHER WILL BE A CONCERN. MEANWHILE...COLD FRONT IS APPROACHING NORTHWEST YUMA COUNTY SLIGHTLY AHEAD OF SCHEDULE. PRECIPITATION IS HANGING BACK IN WYOMING WELL BEHIND THE FRONT...BUT THERE IS FOG/STRATUS IN THE NEBRASKA PANHANDLE AND THAT MIGHT REACH THE NORTHWEST FORECAST AREA LATER THIS AFTERNOON. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 401 AM MST MON JAN 28 2013 ONCE AGAIN THERE ARE NUMEROUS FORECAST PROBLEMS TO ADDRESS THROUGH THE SHORT TERM. SATELLITE SHOWING A COMPLICATED AND AMPLIFIED FLOW FROM THE PACIFIC INTO WESTERN NORTH AMERICA. RATHER STRONG/COLD AND POSITIVELY TILTED TROUGH IS APPROACHING FROM THE WEST THIS MORNING. COOL AND MOIST AIR MASS OVER THE AREA THIS MORNING IS EXPECTED TO GIVE WAY TO A WARMER AIR MASS THAT IS NOT TOO FAR AWAY. AT JET LEVEL...THE ECMWF AND CANADIAN WERE DOING A LITTLE BETTER THAN THE OTHERS WITH THE JET SEGMENT THAT IS GETTING CLOSER TO US. THAT OUTPUT WAS A LITTLE TOO FAR EAST. MODELS INITIALIZED WELL AT MID LEVELS. AT THE SURFACE...THE MODELS TENDED TO HAVE THE FRONT TO OUR SOUTH AND THE SURFACE TROUGH TO OUR WEST...TO FAR NORTH AND EAST. THE SREF WAS DOING A LITTLE BETTER THAN THE ECMWF AND NAM. THE RUC AND HRRR ARE CATCHING THE FOG WITH THE NAM NOT HAVING A CLUE ABOUT IT LIKE LAST NIGHT. THE SREF IS DOING BEST ON THE LOW LEVEL THERMAL FIELD AND IS A LITTLE BETTER THAN THE UKMET...ECMWF...AND GFS. TODAY/TONIGHT...FIRST CONCERN WHICH THE EVENING SHIFT ALREADY ADDRESSED HAS BEEN DENSE FOG. WILL CONTINUE TO MONITOR TRENDS. AT THIS TIME WILL KEEP THE CURRENT AREA OF THE ADVISORY BUT THERE ARE INDICATIONS THAT THE ADVISORY MAY NEED TO BE EXPANDED. BIG KEYS ON THE MAX TEMPERATURES IS HOW FAST THE STRATUS/FOG RETREATS/ENDS AND WHEN THE COLD FRONT LOOKS TO START MOVING IN THE NORTH. THE MODELS ARE SLOWER WITH THE FRONT. RUC/HRRR HAVE A GOOD HANDLE ON THE STRATUS/FOG AREA. IT LOOKS LIKE THE FAR NORTHEAST CORNER COULD NOT CLEAR UNTIL LATER THIS AFTERNOON. IF THAT IS THE CASE...THE TEMPERATURES I HAVE UP THERE WILL BE TOO WARM. SUFFICE TO SAY THERE COULD BE A HUGE GRADIENT IN TEMPERATURES TODAY. AND IF THAT IS NOT BAD ENOUGH...SOME MID AND HIGH LEVEL CLOUD COVER WILL START INCREASE IN THE WEST IN THE AFTERNOON. COMPARING THE RUC/HRRR TO THE BETTER 850 MB TEMPERATURE GUIDANCE WOULD SUPPORT 60S OVER AREAS THAT GET A LOT OF SUN...MAYBE EVEN 70 DEGREE READING. AS SURFACE RIDGE MOVES AWAY AND SURFACE LOW OVER EASTERN STRENGTHENS...GRADIENT IS EXPECTED TO TIGHTEN ALONG WITH MODERATE 3 HOUR PRESSURE FALLS. SO OVER THE SOUTHWEST PORTION OF THE AREA IT COULD GET BREEZY TO WINDY. THIS MAY CAUSE SOME FIRE WEATHER ISSUES. REFER TO THE FIRE WEATHER SECTION BELOW. BY LATE AFTERNOON...THE RIGHT REAR QUADRANT OF THE JET WILL BE AFFECTING THE SOUTHEAST HALF OF THE AREA. BY LATE EVENING THIS HAS MOVED EAST OF THE AREA. THIS JET LIFT IS OUT OF PHASE WITH THE DEEPER MOISTURE AND OTHER LIFT. AT THIS TIME ONLY EXPECT CLOUDS IN THE AFTERNOON FOR MOST OF THE AREA THIS AFTERNOON. AFTER THAT...ABOVE MENTIONED UPPER TROUGH...WITH RATHER COLD AIR ALOFT...IS EXPECTED TO START MOVE THROUGH DURING THE NIGHT. ON THE SOUTHERN END OF THIS TROUGH SPORADIC LIGHTNING STRIKES HAVE BEEN DETECTED. AM CONCERNED THIS SYSTEM IS COMING IN A LITTLE STRONGER THAN 00Z MODELS SHOWED DESPITE BEING AN OPEN WAVE AND MOVING THROUGH RATHER QUICKLY. NEWER DATA COME IN WITH A LITTLE BETTER MOISTURE PROFILE. AT THIS TIME THE NORTHWEST PORTION OF THE AREA CAME IN WITH THE BEST MOISTURE...INSTABILITY...AND LIFT SETUP. SO MADE THE HIGHEST POPS IN THERE DURING THE NIGHT. THE BEST PARAMETERS DO NOT REALLY START COMING INTO THE AREA UNTIL LATE IN THE EVENING. GRADIENT AND 3 HOUR PRESSURE RISES SUPPORT BREEZY TO MAYBE WINDY BEHIND THE FRONT. TUESDAY/TUESDAY NIGHT...TROUGH IS STILL TO THE WEST OF THE AREA AT 12Z WITH A RATHER STRONG PV ANOMALY INDICATED WITH IT. TROUGH/ANOMALY MOVE ACROSS DURING THE DAY. DESPITE WHAT APPEARS NOT THE BEST OF MOISTURE PROFILES...THE INSTABILITY AND STRENGTH OF THIS SYSTEM HAS ME CONCERNED ABOUT MEASURABLE SNOW/PRECIPITATION. SO RAISED POPS INTO THE 20 TO 30 PERCENT RANGE BUT COULD SEE THE POSSIBILITY OF NEEDING HIGHER POPS. ALSO IF THERE ENDS UP BEING MORE SNOW THAN I THINK...THERE COULD BE SOME BLOWING SNOW DUE TO THE STRONG AND GUSTY WINDS. IT IS POSSIBLE THAT THE WINDS COULD GET CLOSE TO WIND ADVISORY CRITERIA. MODELS ARE COMING IN COLDER AND MORE EXTENSIVE CLOUD COVER. SO REDUCED MAXES AND IF THE COLDER MODELS WORK OUT...I MAY BE TOO WARM. ANOTHER SHORTWAVE TROUGH...WEAK JET LIFT AND A REINFORCING SHORT OF COLD AIR COULD KEEP FLURRIES GOING THROUGH THE NIGHT. WEDNESDAY/WEDNESDAY NIGHT...SO HOW COLD DOES IT REMAIN BEHIND EXITING SYSTEM. MODELS IN GOOD AGREEMENT IN BRINGING IN MUCH COLDER ONCE THE TROUGH HAS MOVED TO THE EAST. ALSO AN INDICATION THAT THERE MAY BE MORE CLOUD COVER THAN INDICATED. SO LOWERED MAXES AGAIN. AGAIN WITH STRONG CYCLONIC FLOW WITH EMBEDDED SHORTWAVES...FLURRIES COULD BE A POSSIBILITY. THIS FLURRY ACTIVITY ENDS DURING THE EVENING. .LONG TERM...(THURSDAY THROUGH SUNDAY) ISSUED AT 253 AM MST MON JAN 28 2013 MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD. THE LARGE UPPER LEVEL TROUGH ACROSS THE CENTRAL AND EASTERN UNITED STATES WILL CONTINUE MOVING SLOWLY TO THE EAST AND AN UPPER LEVEL RIDGE OF HIGH PRESSURE SHOULD BUILD IN FROM THE WEST TOWARDS THE END OF THE WEEK. A SURFACE HIGH PRESSURE WILL ALSO BECOME A PERSISTENT FEATURE ACROSS THE PLAINS. WITH A RIDGE OF HIGH PRESSURE BUILDING IN AND PERSISTENT SURFACE HIGH...PRECIPITATION CHANCES THROUGH MOST OF THE EXTENDED FORECAST APPEAR MINIMAL. THE ONLY CHANCE WOULD BE ON THURSDAY AS A WEAK SHORTWAVE ROTATES AROUND THE EDGE OF THE UPPER LEVEL TROUGH. MODELS HAVE BACKED OFF ON THE COVERAGE AND QPF AMOUNTS ACROSS THE TRI-STATE AREA SO HAVE MADE CHANGES IN THE FORECAST TO REFLECT THIS. AT THE PRESENT TIME...NO PRECIPITATION IS MENTIONED. THE TRICKY PORTION OF THE EXTENDED FORECAST CONCERNS THE HIGH TEMPERATURES. ON THURSDAY...MODELS INDICATE A TIGHT TEMPERATURE GRADIENT ACROSS THE REGION AS THE COLD FRONT THAT MOVES THROUGH ON MONDAY NIGHT LINGERS. THERE ARE SLIGHT DIFFERENCES IN THE GRADIENT LOCATION BETWEEN THE GFS...CANADIAN AND EUROPEAN MODELS. THE GFS IS COOLER THAN THE EUROPEAN SOLUTION BY 7 TO 8 DEGREES AS A RESULT. FOR FRIDAY THROUGH SUNDAY...A WARMING TREND IS EXPECTED AS ALL MODELS SHOW TEMPERATURES AT 850 MB WARMING. MODELS ARE IN BETTER AGREEMENT IN THIS TIME FRAME WITH GUIDANCE WITHIN A FEW DEGREES EACH DAY. THE GENERAL PATTERN THAT MODELS ARE PROJECTING IS VERY SIMILAR TO THE WARM SCENARIO THAT PLAYED OUT LAST WEEK. RAISED HIGH TEMPERATURES EACH DAY AS A RESULT OF LAST WEEKS WEATHER AND CONTINUED DROUGHT CONDITIONS. BOTH THE GFS AND EUROPEAN MODELS SHOW 850 MB TEMPERATURES CREEPING UP TO 10 DEGREES CELSIUS FOR SUNDAY...SO HAVE MADE SUNDAY THE WARMEST DAY IN THE EXTENDED WITH HIGHS APPROACHING 60 FOR MOST OF THE REGION. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 456 AM MST MON JAN 28 2013 HRRR CONTINUES TO HANDLE STRATUS AND FOG FIELD VERY WELL. FOR KGLD...IT LOOKS LIKE IFR/LIFR CONDITIONS WILL STAY TO THE EAST OF THE SITE THIS MORNING. KGLD MAY GET SOME BRIEF CONDITIONS BEFORE IMPROVING BY MID MORNING. OTHERWISE AT KGLD...AN UPPER LEVEL STORM SYSTEM AND ASSOCIATED COLD FRONT WILL MOVE INTO THE AREA TONIGHT. THIS WILL SPREAD MVFR AND POSSIBLE IFR CONDITIONS INTO THE AREA BEGINNING AROUND 04Z. MAY BE SOME SNOW AROUND HOWEVER CHOSE TO HANDLE WITH VCSH SINCE TOWARD THE END OF THE PERIOD. FOR KMCK...LIFR CONDITIONS WILL LAST THROUGH LATE MORNING BEFORE IMPROVEMENT. IT IS POSSIBLE IFR/MVFR CONDITIONS COULD LAST A FEW HOURS BEYOND THIS BUT LATER SHIFTS CAN ADDRESS WHEN IT BECOMES MORE CLEAR. STORM SYSTEM AND COLD FRONT MOVE INTO THE AREA LATER THIS EVENING. THIS WILL BRING IFR TO MVFR CEILINGS BACK TO THE AREA WITH LIGHT SNOW SHOWERS POSSIBLE AS WELL. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR KSZ002>004. CO...NONE. NE...DENSE FOG ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR NEZ080-081. && $$ UPDATE...024 SHORT TERM...BULLER LONG TERM...RRH AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1216 PM MST MON JAN 28 2013 .UPDATE... ISSUED AT 1208 PM MST MON JAN 28 2013 REMOVED LOGAN AND GOVE COUNTIES FROM THE DENSE FOG ADVISORY. THE FOG AND STRATUS IS QUICKLY ERODING NORTH TO SOUTH...WILL PROBABLY BE ABLE TO CANCEL THOMAS...SHERIDAN AND GRAHAM COUNTIES NEXT HOUR. TEMPERATURES ARE WARMING INTO THE 60S OUTSIDE OF THE FOG AREAS. SOUTHWEST WINDS WILL INCREASE TO 20 TO 30 MPH WITH HIGHER GUSTS. IT WILL BE MARGINAL FOR A WIND ADVISORY AND DO NOT PLAN ONE UNLESS WINDS INCREASE MORE. RH VALUES ARE STAYING ABOVE 20 PERCENT SO DO NOT THINK FIRE WEATHER WILL BE A CONCERN. MEANWHILE...COLD FRONT IS APPROACHING NORTHWEST YUMA COUNTY SLIGHTLY AHEAD OF SCHEDULE. PRECIPITATION IS HANGING BACK IN WYOMING WELL BEHIND THE FRONT...BUT THERE IS FOG/STRATUS IN THE NEBRASKA PANHANDLE AND THAT MIGHT REACH THE NORTHWEST FORECAST AREA LATER THIS AFTERNOON. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 401 AM MST MON JAN 28 2013 ONCE AGAIN THERE ARE NUMEROUS FORECAST PROBLEMS TO ADDRESS THROUGH THE SHORT TERM. SATELLITE SHOWING A COMPLICATED AND AMPLIFIED FLOW FROM THE PACIFIC INTO WESTERN NORTH AMERICA. RATHER STRONG/COLD AND POSITIVELY TILTED TROUGH IS APPROACHING FROM THE WEST THIS MORNING. COOL AND MOIST AIR MASS OVER THE AREA THIS MORNING IS EXPECTED TO GIVE WAY TO A WARMER AIR MASS THAT IS NOT TOO FAR AWAY. AT JET LEVEL...THE ECMWF AND CANADIAN WERE DOING A LITTLE BETTER THAN THE OTHERS WITH THE JET SEGMENT THAT IS GETTING CLOSER TO US. THAT OUTPUT WAS A LITTLE TOO FAR EAST. MODELS INITIALIZED WELL AT MID LEVELS. AT THE SURFACE...THE MODELS TENDED TO HAVE THE FRONT TO OUR SOUTH AND THE SURFACE TROUGH TO OUR WEST...TO FAR NORTH AND EAST. THE SREF WAS DOING A LITTLE BETTER THAN THE ECMWF AND NAM. THE RUC AND HRRR ARE CATCHING THE FOG WITH THE NAM NOT HAVING A CLUE ABOUT IT LIKE LAST NIGHT. THE SREF IS DOING BEST ON THE LOW LEVEL THERMAL FIELD AND IS A LITTLE BETTER THAN THE UKMET...ECMWF...AND GFS. TODAY/TONIGHT...FIRST CONCERN WHICH THE EVENING SHIFT ALREADY ADDRESSED HAS BEEN DENSE FOG. WILL CONTINUE TO MONITOR TRENDS. AT THIS TIME WILL KEEP THE CURRENT AREA OF THE ADVISORY BUT THERE ARE INDICATIONS THAT THE ADVISORY MAY NEED TO BE EXPANDED. BIG KEYS ON THE MAX TEMPERATURES IS HOW FAST THE STRATUS/FOG RETREATS/ENDS AND WHEN THE COLD FRONT LOOKS TO START MOVING IN THE NORTH. THE MODELS ARE SLOWER WITH THE FRONT. RUC/HRRR HAVE A GOOD HANDLE ON THE STRATUS/FOG AREA. IT LOOKS LIKE THE FAR NORTHEAST CORNER COULD NOT CLEAR UNTIL LATER THIS AFTERNOON. IF THAT IS THE CASE...THE TEMPERATURES I HAVE UP THERE WILL BE TOO WARM. SUFFICE TO SAY THERE COULD BE A HUGE GRADIENT IN TEMPERATURES TODAY. AND IF THAT IS NOT BAD ENOUGH...SOME MID AND HIGH LEVEL CLOUD COVER WILL START INCREASE IN THE WEST IN THE AFTERNOON. COMPARING THE RUC/HRRR TO THE BETTER 850 MB TEMPERATURE GUIDANCE WOULD SUPPORT 60S OVER AREAS THAT GET A LOT OF SUN...MAYBE EVEN 70 DEGREE READING. AS SURFACE RIDGE MOVES AWAY AND SURFACE LOW OVER EASTERN STRENGTHENS...GRADIENT IS EXPECTED TO TIGHTEN ALONG WITH MODERATE 3 HOUR PRESSURE FALLS. SO OVER THE SOUTHWEST PORTION OF THE AREA IT COULD GET BREEZY TO WINDY. THIS MAY CAUSE SOME FIRE WEATHER ISSUES. REFER TO THE FIRE WEATHER SECTION BELOW. BY LATE AFTERNOON...THE RIGHT REAR QUADRANT OF THE JET WILL BE AFFECTING THE SOUTHEAST HALF OF THE AREA. BY LATE EVENING THIS HAS MOVED EAST OF THE AREA. THIS JET LIFT IS OUT OF PHASE WITH THE DEEPER MOISTURE AND OTHER LIFT. AT THIS TIME ONLY EXPECT CLOUDS IN THE AFTERNOON FOR MOST OF THE AREA THIS AFTERNOON. AFTER THAT...ABOVE MENTIONED UPPER TROUGH...WITH RATHER COLD AIR ALOFT...IS EXPECTED TO START MOVE THROUGH DURING THE NIGHT. ON THE SOUTHERN END OF THIS TROUGH SPORADIC LIGHTNING STRIKES HAVE BEEN DETECTED. AM CONCERNED THIS SYSTEM IS COMING IN A LITTLE STRONGER THAN 00Z MODELS SHOWED DESPITE BEING AN OPEN WAVE AND MOVING THROUGH RATHER QUICKLY. NEWER DATA COME IN WITH A LITTLE BETTER MOISTURE PROFILE. AT THIS TIME THE NORTHWEST PORTION OF THE AREA CAME IN WITH THE BEST MOISTURE...INSTABILITY...AND LIFT SETUP. SO MADE THE HIGHEST POPS IN THERE DURING THE NIGHT. THE BEST PARAMETERS DO NOT REALLY START COMING INTO THE AREA UNTIL LATE IN THE EVENING. GRADIENT AND 3 HOUR PRESSURE RISES SUPPORT BREEZY TO MAYBE WINDY BEHIND THE FRONT. TUESDAY/TUESDAY NIGHT...TROUGH IS STILL TO THE WEST OF THE AREA AT 12Z WITH A RATHER STRONG PV ANOMALY INDICATED WITH IT. TROUGH/ANOMALY MOVE ACROSS DURING THE DAY. DESPITE WHAT APPEARS NOT THE BEST OF MOISTURE PROFILES...THE INSTABILITY AND STRENGTH OF THIS SYSTEM HAS ME CONCERNED ABOUT MEASURABLE SNOW/PRECIPITATION. SO RAISED POPS INTO THE 20 TO 30 PERCENT RANGE BUT COULD SEE THE POSSIBILITY OF NEEDING HIGHER POPS. ALSO IF THERE ENDS UP BEING MORE SNOW THAN I THINK...THERE COULD BE SOME BLOWING SNOW DUE TO THE STRONG AND GUSTY WINDS. IT IS POSSIBLE THAT THE WINDS COULD GET CLOSE TO WIND ADVISORY CRITERIA. MODELS ARE COMING IN COLDER AND MORE EXTENSIVE CLOUD COVER. SO REDUCED MAXES AND IF THE COLDER MODELS WORK OUT...I MAY BE TOO WARM. ANOTHER SHORTWAVE TROUGH...WEAK JET LIFT AND A REINFORCING SHORT OF COLD AIR COULD KEEP FLURRIES GOING THROUGH THE NIGHT. WEDNESDAY/WEDNESDAY NIGHT...SO HOW COLD DOES IT REMAIN BEHIND EXITING SYSTEM. MODELS IN GOOD AGREEMENT IN BRINGING IN MUCH COLDER ONCE THE TROUGH HAS MOVED TO THE EAST. ALSO AN INDICATION THAT THERE MAY BE MORE CLOUD COVER THAN INDICATED. SO LOWERED MAXES AGAIN. AGAIN WITH STRONG CYCLONIC FLOW WITH EMBEDDED SHORTWAVES...FLURRIES COULD BE A POSSIBILITY. THIS FLURRY ACTIVITY ENDS DURING THE EVENING. .LONG TERM...(THURSDAY THROUGH SUNDAY) ISSUED AT 253 AM MST MON JAN 28 2013 MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD. THE LARGE UPPER LEVEL TROUGH ACROSS THE CENTRAL AND EASTERN UNITED STATES WILL CONTINUE MOVING SLOWLY TO THE EAST AND AN UPPER LEVEL RIDGE OF HIGH PRESSURE SHOULD BUILD IN FROM THE WEST TOWARDS THE END OF THE WEEK. A SURFACE HIGH PRESSURE WILL ALSO BECOME A PERSISTENT FEATURE ACROSS THE PLAINS. WITH A RIDGE OF HIGH PRESSURE BUILDING IN AND PERSISTENT SURFACE HIGH...PRECIPITATION CHANCES THROUGH MOST OF THE EXTENDED FORECAST APPEAR MINIMAL. THE ONLY CHANCE WOULD BE ON THURSDAY AS A WEAK SHORTWAVE ROTATES AROUND THE EDGE OF THE UPPER LEVEL TROUGH. MODELS HAVE BACKED OFF ON THE COVERAGE AND QPF AMOUNTS ACROSS THE TRI-STATE AREA SO HAVE MADE CHANGES IN THE FORECAST TO REFLECT THIS. AT THE PRESENT TIME...NO PRECIPITATION IS MENTIONED. THE TRICKY PORTION OF THE EXTENDED FORECAST CONCERNS THE HIGH TEMPERATURES. ON THURSDAY...MODELS INDICATE A TIGHT TEMPERATURE GRADIENT ACROSS THE REGION AS THE COLD FRONT THAT MOVES THROUGH ON MONDAY NIGHT LINGERS. THERE ARE SLIGHT DIFFERENCES IN THE GRADIENT LOCATION BETWEEN THE GFS...CANADIAN AND EUROPEAN MODELS. THE GFS IS COOLER THAN THE EUROPEAN SOLUTION BY 7 TO 8 DEGREES AS A RESULT. FOR FRIDAY THROUGH SUNDAY...A WARMING TREND IS EXPECTED AS ALL MODELS SHOW TEMPERATURES AT 850 MB WARMING. MODELS ARE IN BETTER AGREEMENT IN THIS TIME FRAME WITH GUIDANCE WITHIN A FEW DEGREES EACH DAY. THE GENERAL PATTERN THAT MODELS ARE PROJECTING IS VERY SIMILAR TO THE WARM SCENARIO THAT PLAYED OUT LAST WEEK. RAISED HIGH TEMPERATURES EACH DAY AS A RESULT OF LAST WEEKS WEATHER AND CONTINUED DROUGHT CONDITIONS. BOTH THE GFS AND EUROPEAN MODELS SHOW 850 MB TEMPERATURES CREEPING UP TO 10 DEGREES CELSIUS FOR SUNDAY...SO HAVE MADE SUNDAY THE WARMEST DAY IN THE EXTENDED WITH HIGHS APPROACHING 60 FOR MOST OF THE REGION. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 456 AM MST MON JAN 28 2013 HRRR CONTINUES TO HANDLE STRATUS AND FOG FIELD VERY WELL. FOR KGLD...IT LOOKS LIKE IFR/LIFR CONDITIONS WILL STAY TO THE EAST OF THE SITE THIS MORNING. KGLD MAY GET SOME BRIEF CONDITIONS BEFORE IMPROVING BY MID MORNING. OTHERWISE AT KGLD...AN UPPER LEVEL STORM SYSTEM AND ASSOCIATED COLD FRONT WILL MOVE INTO THE AREA TONIGHT. THIS WILL SPREAD MVFR AND POSSIBLE IFR CONDITIONS INTO THE AREA BEGINNING AROUND 04Z. MAY BE SOME SNOW AROUND HOWEVER CHOSE TO HANDLE WITH VCSH SINCE TOWARD THE END OF THE PERIOD. FOR KMCK...LIFR CONDITIONS WILL LAST THROUGH LATE MORNING BEFORE IMPROVEMENT. IT IS POSSIBLE IFR/MVFR CONDITIONS COULD LAST A FEW HOURS BEYOND THIS BUT LATER SHIFTS CAN ADDRESS WHEN IT BECOMES MORE CLEAR. STORM SYSTEM AND COLD FRONT MOVE INTO THE AREA LATER THIS EVENING. THIS WILL BRING IFR TO MVFR CEILINGS BACK TO THE AREA WITH LIGHT SNOW SHOWERS POSSIBLE AS WELL. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR KSZ002>004- 014>016. CO...NONE. NE...DENSE FOG ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR NEZ080-081. && $$ UPDATE...024 SHORT TERM...BULLER LONG TERM...RRH AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1214 PM MST MON JAN 28 2013 .UPDATE... ISSUED AT 1208 PM MST MON JAN 28 2013 REMOVED LOGAN AND GOVE COUNTIES FROM THE DENSE FOG ADVISORIES. THE FOG AND STRATUS IS QUICKLY ERODING NORTH TO SOUTH...WILL PROBABLY BE ABLE TO CANCEL THOMAS...SHERIDAN AND GRAHAM COUNTIES NEXT HOUR. TEMPERATURES ARE WARMING INTO THE 60S OUTSIDE OF THE FOG AREAS. SOUTHWEST WINDS WILL INCREASE TO 20 TO 30 MPH WITH HIGHER GUSTS. IT WILL BE MARGINAL FOR A WIND ADVISORY AND DO NOT PLAN ONE UNLESS WINDS INCREASE MORE. RH VALUES ARE STAYING ABOVE 20 PERCENT SO DO NOT THINK FIRE WEATHER WILL BE A CONCERN. MEANWHILE...COLD FRONT IS APPROACHING NORTHWEST YUMA COUNTY SLIGHTLY AHEAD OF SCHEDULE. PRECIPITATION IS HANGING BACK IN WYOMING WELL BEHIND THE FRONT...BUT THERE IS FOG/STRATUS IN THE NEBRASKA PANHANDLE AND THAT MIGHT REACH THE NORTHWEST FORECAST AREA LATER THIS AFTERNOON. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 401 AM MST MON JAN 28 2013 ONCE AGAIN THERE ARE NUMEROUS FORECAST PROBLEMS TO ADDRESS THROUGH THE SHORT TERM. SATELLITE SHOWING A COMPLICATED AND AMPLIFIED FLOW FROM THE PACIFIC INTO WESTERN NORTH AMERICA. RATHER STRONG/COLD AND POSITIVELY TILTED TROUGH IS APPROACHING FROM THE WEST THIS MORNING. COOL AND MOIST AIR MASS OVER THE AREA THIS MORNING IS EXPECTED TO GIVE WAY TO A WARMER AIR MASS THAT IS NOT TOO FAR AWAY. AT JET LEVEL...THE ECMWF AND CANADIAN WERE DOING A LITTLE BETTER THAN THE OTHERS WITH THE JET SEGMENT THAT IS GETTING CLOSER TO US. THAT OUTPUT WAS A LITTLE TOO FAR EAST. MODELS INITIALIZED WELL AT MID LEVELS. AT THE SURFACE...THE MODELS TENDED TO HAVE THE FRONT TO OUR SOUTH AND THE SURFACE TROUGH TO OUR WEST...TO FAR NORTH AND EAST. THE SREF WAS DOING A LITTLE BETTER THAN THE ECMWF AND NAM. THE RUC AND HRRR ARE CATCHING THE FOG WITH THE NAM NOT HAVING A CLUE ABOUT IT LIKE LAST NIGHT. THE SREF IS DOING BEST ON THE LOW LEVEL THERMAL FIELD AND IS A LITTLE BETTER THAN THE UKMET...ECMWF...AND GFS. TODAY/TONIGHT...FIRST CONCERN WHICH THE EVENING SHIFT ALREADY ADDRESSED HAS BEEN DENSE FOG. WILL CONTINUE TO MONITOR TRENDS. AT THIS TIME WILL KEEP THE CURRENT AREA OF THE ADVISORY BUT THERE ARE INDICATIONS THAT THE ADVISORY MAY NEED TO BE EXPANDED. BIG KEYS ON THE MAX TEMPERATURES IS HOW FAST THE STRATUS/FOG RETREATS/ENDS AND WHEN THE COLD FRONT LOOKS TO START MOVING IN THE NORTH. THE MODELS ARE SLOWER WITH THE FRONT. RUC/HRRR HAVE A GOOD HANDLE ON THE STRATUS/FOG AREA. IT LOOKS LIKE THE FAR NORTHEAST CORNER COULD NOT CLEAR UNTIL LATER THIS AFTERNOON. IF THAT IS THE CASE...THE TEMPERATURES I HAVE UP THERE WILL BE TOO WARM. SUFFICE TO SAY THERE COULD BE A HUGE GRADIENT IN TEMPERATURES TODAY. AND IF THAT IS NOT BAD ENOUGH...SOME MID AND HIGH LEVEL CLOUD COVER WILL START INCREASE IN THE WEST IN THE AFTERNOON. COMPARING THE RUC/HRRR TO THE BETTER 850 MB TEMPERATURE GUIDANCE WOULD SUPPORT 60S OVER AREAS THAT GET A LOT OF SUN...MAYBE EVEN 70 DEGREE READING. AS SURFACE RIDGE MOVES AWAY AND SURFACE LOW OVER EASTERN STRENGTHENS...GRADIENT IS EXPECTED TO TIGHTEN ALONG WITH MODERATE 3 HOUR PRESSURE FALLS. SO OVER THE SOUTHWEST PORTION OF THE AREA IT COULD GET BREEZY TO WINDY. THIS MAY CAUSE SOME FIRE WEATHER ISSUES. REFER TO THE FIRE WEATHER SECTION BELOW. BY LATE AFTERNOON...THE RIGHT REAR QUADRANT OF THE JET WILL BE AFFECTING THE SOUTHEAST HALF OF THE AREA. BY LATE EVENING THIS HAS MOVED EAST OF THE AREA. THIS JET LIFT IS OUT OF PHASE WITH THE DEEPER MOISTURE AND OTHER LIFT. AT THIS TIME ONLY EXPECT CLOUDS IN THE AFTERNOON FOR MOST OF THE AREA THIS AFTERNOON. AFTER THAT...ABOVE MENTIONED UPPER TROUGH...WITH RATHER COLD AIR ALOFT...IS EXPECTED TO START MOVE THROUGH DURING THE NIGHT. ON THE SOUTHERN END OF THIS TROUGH SPORADIC LIGHTNING STRIKES HAVE BEEN DETECTED. AM CONCERNED THIS SYSTEM IS COMING IN A LITTLE STRONGER THAN 00Z MODELS SHOWED DESPITE BEING AN OPEN WAVE AND MOVING THROUGH RATHER QUICKLY. NEWER DATA COME IN WITH A LITTLE BETTER MOISTURE PROFILE. AT THIS TIME THE NORTHWEST PORTION OF THE AREA CAME IN WITH THE BEST MOISTURE...INSTABILITY...AND LIFT SETUP. SO MADE THE HIGHEST POPS IN THERE DURING THE NIGHT. THE BEST PARAMETERS DO NOT REALLY START COMING INTO THE AREA UNTIL LATE IN THE EVENING. GRADIENT AND 3 HOUR PRESSURE RISES SUPPORT BREEZY TO MAYBE WINDY BEHIND THE FRONT. TUESDAY/TUESDAY NIGHT...TROUGH IS STILL TO THE WEST OF THE AREA AT 12Z WITH A RATHER STRONG PV ANOMALY INDICATED WITH IT. TROUGH/ANOMALY MOVE ACROSS DURING THE DAY. DESPITE WHAT APPEARS NOT THE BEST OF MOISTURE PROFILES...THE INSTABILITY AND STRENGTH OF THIS SYSTEM HAS ME CONCERNED ABOUT MEASURABLE SNOW/PRECIPITATION. SO RAISED POPS INTO THE 20 TO 30 PERCENT RANGE BUT COULD SEE THE POSSIBILITY OF NEEDING HIGHER POPS. ALSO IF THERE ENDS UP BEING MORE SNOW THAN I THINK...THERE COULD BE SOME BLOWING SNOW DUE TO THE STRONG AND GUSTY WINDS. IT IS POSSIBLE THAT THE WINDS COULD GET CLOSE TO WIND ADVISORY CRITERIA. MODELS ARE COMING IN COLDER AND MORE EXTENSIVE CLOUD COVER. SO REDUCED MAXES AND IF THE COLDER MODELS WORK OUT...I MAY BE TOO WARM. ANOTHER SHORTWAVE TROUGH...WEAK JET LIFT AND A REINFORCING SHORT OF COLD AIR COULD KEEP FLURRIES GOING THROUGH THE NIGHT. WEDNESDAY/WEDNESDAY NIGHT...SO HOW COLD DOES IT REMAIN BEHIND EXITING SYSTEM. MODELS IN GOOD AGREEMENT IN BRINGING IN MUCH COLDER ONCE THE TROUGH HAS MOVED TO THE EAST. ALSO AN INDICATION THAT THERE MAY BE MORE CLOUD COVER THAN INDICATED. SO LOWERED MAXES AGAIN. AGAIN WITH STRONG CYCLONIC FLOW WITH EMBEDDED SHORTWAVES...FLURRIES COULD BE A POSSIBILITY. THIS FLURRY ACTIVITY ENDS DURING THE EVENING. .LONG TERM...(THURSDAY THROUGH SUNDAY) ISSUED AT 253 AM MST MON JAN 28 2013 MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD. THE LARGE UPPER LEVEL TROUGH ACROSS THE CENTRAL AND EASTERN UNITED STATES WILL CONTINUE MOVING SLOWLY TO THE EAST AND AN UPPER LEVEL RIDGE OF HIGH PRESSURE SHOULD BUILD IN FROM THE WEST TOWARDS THE END OF THE WEEK. A SURFACE HIGH PRESSURE WILL ALSO BECOME A PERSISTENT FEATURE ACROSS THE PLAINS. WITH A RIDGE OF HIGH PRESSURE BUILDING IN AND PERSISTENT SURFACE HIGH...PRECIPITATION CHANCES THROUGH MOST OF THE EXTENDED FORECAST APPEAR MINIMAL. THE ONLY CHANCE WOULD BE ON THURSDAY AS A WEAK SHORTWAVE ROTATES AROUND THE EDGE OF THE UPPER LEVEL TROUGH. MODELS HAVE BACKED OFF ON THE COVERAGE AND QPF AMOUNTS ACROSS THE TRI-STATE AREA SO HAVE MADE CHANGES IN THE FORECAST TO REFLECT THIS. AT THE PRESENT TIME...NO PRECIPITATION IS MENTIONED. THE TRICKY PORTION OF THE EXTENDED FORECAST CONCERNS THE HIGH TEMPERATURES. ON THURSDAY...MODELS INDICATE A TIGHT TEMPERATURE GRADIENT ACROSS THE REGION AS THE COLD FRONT THAT MOVES THROUGH ON MONDAY NIGHT LINGERS. THERE ARE SLIGHT DIFFERENCES IN THE GRADIENT LOCATION BETWEEN THE GFS...CANADIAN AND EUROPEAN MODELS. THE GFS IS COOLER THAN THE EUROPEAN SOLUTION BY 7 TO 8 DEGREES AS A RESULT. FOR FRIDAY THROUGH SUNDAY...A WARMING TREND IS EXPECTED AS ALL MODELS SHOW TEMPERATURES AT 850 MB WARMING. MODELS ARE IN BETTER AGREEMENT IN THIS TIME FRAME WITH GUIDANCE WITHIN A FEW DEGREES EACH DAY. THE GENERAL PATTERN THAT MODELS ARE PROJECTING IS VERY SIMILAR TO THE WARM SCENARIO THAT PLAYED OUT LAST WEEK. RAISED HIGH TEMPERATURES EACH DAY AS A RESULT OF LAST WEEKS WEATHER AND CONTINUED DROUGHT CONDITIONS. BOTH THE GFS AND EUROPEAN MODELS SHOW 850 MB TEMPERATURES CREEPING UP TO 10 DEGREES CELSIUS FOR SUNDAY...SO HAVE MADE SUNDAY THE WARMEST DAY IN THE EXTENDED WITH HIGHS APPROACHING 60 FOR MOST OF THE REGION. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 456 AM MST MON JAN 28 2013 HRRR CONTINUES TO HANDLE STRATUS AND FOG FIELD VERY WELL. FOR KGLD...IT LOOKS LIKE IFR/LIFR CONDITIONS WILL STAY TO THE EAST OF THE SITE THIS MORNING. KGLD MAY GET SOME BRIEF CONDITIONS BEFORE IMPROVING BY MID MORNING. OTHERWISE AT KGLD...AN UPPER LEVEL STORM SYSTEM AND ASSOCIATED COLD FRONT WILL MOVE INTO THE AREA TONIGHT. THIS WILL SPREAD MVFR AND POSSIBLE IFR CONDITIONS INTO THE AREA BEGINNING AROUND 04Z. MAY BE SOME SNOW AROUND HOWEVER CHOSE TO HANDLE WITH VCSH SINCE TOWARD THE END OF THE PERIOD. FOR KMCK...LIFR CONDITIONS WILL LAST THROUGH LATE MORNING BEFORE IMPROVEMENT. IT IS POSSIBLE IFR/MVFR CONDITIONS COULD LAST A FEW HOURS BEYOND THIS BUT LATER SHIFTS CAN ADDRESS WHEN IT BECOMES MORE CLEAR. STORM SYSTEM AND COLD FRONT MOVE INTO THE AREA LATER THIS EVENING. THIS WILL BRING IFR TO MVFR CEILINGS BACK TO THE AREA WITH LIGHT SNOW SHOWERS POSSIBLE AS WELL. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR KSZ002>004- 014>016. CO...NONE. NE...DENSE FOG ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR NEZ080-081. && $$ UPDATE...024 SHORT TERM...BULLER LONG TERM...RRH AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1105 AM MST MON JAN 28 2013 .UPDATE... ISSUED AT 1056 AM MST MON JAN 28 2013 EXTENDED DENSE FOG ADVISORY THROUGH 21Z FOR EASTERN AREAS. MAY BE ABLE TO CANCEL A BIT EARLY ACROSS SOUTHERN TIER...LOGAN AND GOVE...AS SATELLITE SHOWING FOG/STRATUS SLOWLY ERODING FROM NORTH TO SOUTH. ALSO ADJUSTED ALL WEATHER PARAMETERS IN NORTHEASTERN AREAS TO ACCOUNT FOR LINGERING STRATUS/FOG. HIGH RESOLUTION SHORT TERM MODELS SHOW THE CLEARING LINE WILL REACH THE KANSAS/NEBRASKA BORDER SOME TIME LATE THIS AFTERNOON. MCCOOK TO NORTON AREAS MAY NOT CLEAR OUT AT ALL AND CONSEQUENTLY SLASHED TEMPERATURES IN THE NORTHEAST CORNER. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 401 AM MST MON JAN 28 2013 ONCE AGAIN THERE ARE NUMEROUS FORECAST PROBLEMS TO ADDRESS THROUGH THE SHORT TERM. SATELLITE SHOWING A COMPLICATED AND AMPLIFIED FLOW FROM THE PACIFIC INTO WESTERN NORTH AMERICA. RATHER STRONG/COLD AND POSITIVELY TILTED TROUGH IS APPROACHING FROM THE WEST THIS MORNING. COOL AND MOIST AIR MASS OVER THE AREA THIS MORNING IS EXPECTED TO GIVE WAY TO A WARMER AIR MASS THAT IS NOT TOO FAR AWAY. AT JET LEVEL...THE ECMWF AND CANADIAN WERE DOING A LITTLE BETTER THAN THE OTHERS WITH THE JET SEGMENT THAT IS GETTING CLOSER TO US. THAT OUTPUT WAS A LITTLE TOO FAR EAST. MODELS INITIALIZED WELL AT MID LEVELS. AT THE SURFACE...THE MODELS TENDED TO HAVE THE FRONT TO OUR SOUTH AND THE SURFACE TROUGH TO OUR WEST...TO FAR NORTH AND EAST. THE SREF WAS DOING A LITTLE BETTER THAN THE ECMWF AND NAM. THE RUC AND HRRR ARE CATCHING THE FOG WITH THE NAM NOT HAVING A CLUE ABOUT IT LIKE LAST NIGHT. THE SREF IS DOING BEST ON THE LOW LEVEL THERMAL FIELD AND IS A LITTLE BETTER THAN THE UKMET...ECMWF...AND GFS. TODAY/TONIGHT...FIRST CONCERN WHICH THE EVENING SHIFT ALREADY ADDRESSED HAS BEEN DENSE FOG. WILL CONTINUE TO MONITOR TRENDS. AT THIS TIME WILL KEEP THE CURRENT AREA OF THE ADVISORY BUT THERE ARE INDICATIONS THAT THE ADVISORY MAY NEED TO BE EXPANDED. BIG KEYS ON THE MAX TEMPERATURES IS HOW FAST THE STRATUS/FOG RETREATS/ENDS AND WHEN THE COLD FRONT LOOKS TO START MOVING IN THE NORTH. THE MODELS ARE SLOWER WITH THE FRONT. RUC/HRRR HAVE A GOOD HANDLE ON THE STRATUS/FOG AREA. IT LOOKS LIKE THE FAR NORTHEAST CORNER COULD NOT CLEAR UNTIL LATER THIS AFTERNOON. IF THAT IS THE CASE...THE TEMPERATURES I HAVE UP THERE WILL BE TOO WARM. SUFFICE TO SAY THERE COULD BE A HUGE GRADIENT IN TEMPERATURES TODAY. AND IF THAT IS NOT BAD ENOUGH...SOME MID AND HIGH LEVEL CLOUD COVER WILL START INCREASE IN THE WEST IN THE AFTERNOON. COMPARING THE RUC/HRRR TO THE BETTER 850 MB TEMPERATURE GUIDANCE WOULD SUPPORT 60S OVER AREAS THAT GET A LOT OF SUN...MAYBE EVEN 70 DEGREE READING. AS SURFACE RIDGE MOVES AWAY AND SURFACE LOW OVER EASTERN STRENGTHENS...GRADIENT IS EXPECTED TO TIGHTEN ALONG WITH MODERATE 3 HOUR PRESSURE FALLS. SO OVER THE SOUTHWEST PORTION OF THE AREA IT COULD GET BREEZY TO WINDY. THIS MAY CAUSE SOME FIRE WEATHER ISSUES. REFER TO THE FIRE WEATHER SECTION BELOW. BY LATE AFTERNOON...THE RIGHT REAR QUADRANT OF THE JET WILL BE AFFECTING THE SOUTHEAST HALF OF THE AREA. BY LATE EVENING THIS HAS MOVED EAST OF THE AREA. THIS JET LIFT IS OUT OF PHASE WITH THE DEEPER MOISTURE AND OTHER LIFT. AT THIS TIME ONLY EXPECT CLOUDS IN THE AFTERNOON FOR MOST OF THE AREA THIS AFTERNOON. AFTER THAT...ABOVE MENTIONED UPPER TROUGH...WITH RATHER COLD AIR ALOFT...IS EXPECTED TO START MOVE THROUGH DURING THE NIGHT. ON THE SOUTHERN END OF THIS TROUGH SPORADIC LIGHTNING STRIKES HAVE BEEN DETECTED. AM CONCERNED THIS SYSTEM IS COMING IN A LITTLE STRONGER THAN 00Z MODELS SHOWED DESPITE BEING AN OPEN WAVE AND MOVING THROUGH RATHER QUICKLY. NEWER DATA COME IN WITH A LITTLE BETTER MOISTURE PROFILE. AT THIS TIME THE NORTHWEST PORTION OF THE AREA CAME IN WITH THE BEST MOISTURE...INSTABILITY...AND LIFT SETUP. SO MADE THE HIGHEST POPS IN THERE DURING THE NIGHT. THE BEST PARAMETERS DO NOT REALLY START COMING INTO THE AREA UNTIL LATE IN THE EVENING. GRADIENT AND 3 HOUR PRESSURE RISES SUPPORT BREEZY TO MAYBE WINDY BEHIND THE FRONT. TUESDAY/TUESDAY NIGHT...TROUGH IS STILL TO THE WEST OF THE AREA AT 12Z WITH A RATHER STRONG PV ANOMALY INDICATED WITH IT. TROUGH/ANOMALY MOVE ACROSS DURING THE DAY. DESPITE WHAT APPEARS NOT THE BEST OF MOISTURE PROFILES...THE INSTABILITY AND STRENGTH OF THIS SYSTEM HAS ME CONCERNED ABOUT MEASURABLE SNOW/PRECIPITATION. SO RAISED POPS INTO THE 20 TO 30 PERCENT RANGE BUT COULD SEE THE POSSIBILITY OF NEEDING HIGHER POPS. ALSO IF THERE ENDS UP BEING MORE SNOW THAN I THINK...THERE COULD BE SOME BLOWING SNOW DUE TO THE STRONG AND GUSTY WINDS. IT IS POSSIBLE THAT THE WINDS COULD GET CLOSE TO WIND ADVISORY CRITERIA. MODELS ARE COMING IN COLDER AND MORE EXTENSIVE CLOUD COVER. SO REDUCED MAXES AND IF THE COLDER MODELS WORK OUT...I MAY BE TOO WARM. ANOTHER SHORTWAVE TROUGH...WEAK JET LIFT AND A REINFORCING SHORT OF COLD AIR COULD KEEP FLURRIES GOING THROUGH THE NIGHT. WEDNESDAY/WEDNESDAY NIGHT...SO HOW COLD DOES IT REMAIN BEHIND EXITING SYSTEM. MODELS IN GOOD AGREEMENT IN BRINGING IN MUCH COLDER ONCE THE TROUGH HAS MOVED TO THE EAST. ALSO AN INDICATION THAT THERE MAY BE MORE CLOUD COVER THAN INDICATED. SO LOWERED MAXES AGAIN. AGAIN WITH STRONG CYCLONIC FLOW WITH EMBEDDED SHORTWAVES...FLURRIES COULD BE A POSSIBILITY. THIS FLURRY ACTIVITY ENDS DURING THE EVENING. .LONG TERM...(THURSDAY THROUGH SUNDAY) ISSUED AT 253 AM MST MON JAN 28 2013 MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD. THE LARGE UPPER LEVEL TROUGH ACROSS THE CENTRAL AND EASTERN UNITED STATES WILL CONTINUE MOVING SLOWLY TO THE EAST AND AN UPPER LEVEL RIDGE OF HIGH PRESSURE SHOULD BUILD IN FROM THE WEST TOWARDS THE END OF THE WEEK. A SURFACE HIGH PRESSURE WILL ALSO BECOME A PERSISTENT FEATURE ACROSS THE PLAINS. WITH A RIDGE OF HIGH PRESSURE BUILDING IN AND PERSISTENT SURFACE HIGH...PRECIPITATION CHANCES THROUGH MOST OF THE EXTENDED FORECAST APPEAR MINIMAL. THE ONLY CHANCE WOULD BE ON THURSDAY AS A WEAK SHORTWAVE ROTATES AROUND THE EDGE OF THE UPPER LEVEL TROUGH. MODELS HAVE BACKED OFF ON THE COVERAGE AND QPF AMOUNTS ACROSS THE TRI-STATE AREA SO HAVE MADE CHANGES IN THE FORECAST TO REFLECT THIS. AT THE PRESENT TIME...NO PRECIPITATION IS MENTIONED. THE TRICKY PORTION OF THE EXTENDED FORECAST CONCERNS THE HIGH TEMPERATURES. ON THURSDAY...MODELS INDICATE A TIGHT TEMPERATURE GRADIENT ACROSS THE REGION AS THE COLD FRONT THAT MOVES THROUGH ON MONDAY NIGHT LINGERS. THERE ARE SLIGHT DIFFERENCES IN THE GRADIENT LOCATION BETWEEN THE GFS...CANADIAN AND EUROPEAN MODELS. THE GFS IS COOLER THAN THE EUROPEAN SOLUTION BY 7 TO 8 DEGREES AS A RESULT. FOR FRIDAY THROUGH SUNDAY...A WARMING TREND IS EXPECTED AS ALL MODELS SHOW TEMPERATURES AT 850 MB WARMING. MODELS ARE IN BETTER AGREEMENT IN THIS TIME FRAME WITH GUIDANCE WITHIN A FEW DEGREES EACH DAY. THE GENERAL PATTERN THAT MODELS ARE PROJECTING IS VERY SIMILAR TO THE WARM SCENARIO THAT PLAYED OUT LAST WEEK. RAISED HIGH TEMPERATURES EACH DAY AS A RESULT OF LAST WEEKS WEATHER AND CONTINUED DROUGHT CONDITIONS. BOTH THE GFS AND EUROPEAN MODELS SHOW 850 MB TEMPERATURES CREEPING UP TO 10 DEGREES CELSIUS FOR SUNDAY...SO HAVE MADE SUNDAY THE WARMEST DAY IN THE EXTENDED WITH HIGHS APPROACHING 60 FOR MOST OF THE REGION. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 456 AM MST MON JAN 28 2013 HRRR CONTINUES TO HANDLE STRATUS AND FOG FIELD VERY WELL. FOR KGLD...IT LOOKS LIKE IFR/LIFR CONDITIONS WILL STAY TO THE EAST OF THE SITE THIS MORNING. KGLD MAY GET SOME BRIEF CONDITIONS BEFORE IMPROVING BY MID MORNING. OTHERWISE AT KGLD...AN UPPER LEVEL STORM SYSTEM AND ASSOCIATED COLD FRONT WILL MOVE INTO THE AREA TONIGHT. THIS WILL SPREAD MVFR AND POSSIBLE IFR CONDITIONS INTO THE AREA BEGINNING AROUND 04Z. MAY BE SOME SNOW AROUND HOWEVER CHOSE TO HANDLE WITH VCSH SINCE TOWARD THE END OF THE PERIOD. FOR KMCK...LIFR CONDITIONS WILL LAST THROUGH LATE MORNING BEFORE IMPROVEMENT. IT IS POSSIBLE IFR/MVFR CONDITIONS COULD LAST A FEW HOURS BEYOND THIS BUT LATER SHIFTS CAN ADDRESS WHEN IT BECOMES MORE CLEAR. STORM SYSTEM AND COLD FRONT MOVE INTO THE AREA LATER THIS EVENING. THIS WILL BRING IFR TO MVFR CEILINGS BACK TO THE AREA WITH LIGHT SNOW SHOWERS POSSIBLE AS WELL. && .FIRE WEATHER... ISSUED AT 401 AM MST MON JAN 28 2013 THE SOUTHWEST PORTION...ESPECIALLY FAR WESTERN CHEYENNE AND KIT CARSON COULD REACH CRITICAL FIRE WEATHER CONDITIONS. AT THIS TIME IT LOOKS LIKE THE RELATIVE HUMIDITIES STAY ABOVE 20 PERCENT WITH ADEQUATE WINDS NOT LASTING THREE HOURS. SO ISSUED NO HIGHLIGHT FOR THIS. BUT DAY SHIFT WILL NEED TO WATCH THIS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR KSZ002>004- 014>016-028-029. CO...NONE. NE...DENSE FOG ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR NEZ080-081. && $$ UPDATE...024 SHORT TERM...BULLER LONG TERM...RRH AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS WICHITA KS
1150 AM CST MON JAN 28 2013 .AVIATION...18Z TAFS KRSL/KSLN/KHUT/KICT/KCNU IFR CONDITIONS SHOULD RAPIDLY IMPROVE AROUND KRSL AT START OF THE FORECAST. VISIBLE SATELLITE LOOP SHOWS BACK EDGE OF FOG/STRATUS JUST SOUTH OF THE AIRPORT. LOW LEVEL MOISTURE WILL CONTINUE TO ADVECT NORTH ACROSS SOUTHEAST KS AND SUSPECT MVFR OR POSSIBLY LOW END VFR WILL PERSIST THROUGHOUT THE AFTERNOON AT KCNU. GUSTY WINDS ARE EXPECTED MOST LOCATIONS THROUGH AT LEAST SUNSET. THE LOW CLOUDS MAY BRIEFLY CLEAR AS DRY SLOT DEVELOPS AHEAD OF COLD FRONT. THE COLD FRONT SHOULD MAKE IT THROUGH KRSL/KSLN ON TUE MORNING. -HOWERTON && .PREV DISCUSSION... /ISSUED 539 AM CST MON JAN 28 2013/ AVIATION...12Z TAFS KRSL/KSLN/KHUT/KICT/KCNU VERY POOR AVIATION CONDITIONS WILL AFFECT ALL OF CENTRAL KANSAS THIS MORNING...WITH DENSE FOG BLANKETING THE REGION. THE FOG WILL BEGIN TO LIFT AS A WARM FRONT MOVES NORTHWARD INTO CENTRAL KANSAS AROUND NOON. SOUTH WINDS WILL INCREASE DURING THE AFTERNOON HOURS AND BECOME GUSTY AS SURFACE LOW PRESSURE DEEPENS OVER WESTERN KANSAS TODAY. MEANWHILE...A COLD FRONT WILL SINK SOUTHWARD INTO CENTRAL KANSAS LATE TONIGHT ALONG WITH SOME MVFR CIGS JUST BEHIND THE FRONTAL BOUNDARY. JAKUB PREV DISCUSSION... /ISSUED 328 AM CST MON JAN 28 2013/ DISCUSSION... FORECAST CONCERNS...DENSE FOG TRENDS THIS MORNING THEN CONVECTIVE CHANCES TONIGHT INTO TUESDAY. TODAY-TUESDAY COMBO OF RADIATIONAL AND ADVECTION FOG DEVELOPING IN VICINITY OF THE SURFACE FRONTAL BOUNDARY WHICH HAS BECOME QUASI-STATIONARY ACROSS THE AREA. THE LATEST RUC WOULD SUGGEST BETTER POTENTIAL FOR DENSE FOG WILL BE REALIZED JUST NORTH OF WICHITA AREA ACROSS CENTRAL KANSAS AS MOIST ADVECTION WITH FRONT DRIFTS SLOWLY NORTH DURING THE MORNING. A DENSE FOG ADVISORY WILL BE ISSUED FOR THESE AREAS. OTHERWISE NEAR RECORD WARMTH EXPECTED THIS AFTERNOON WITH WICHITA/CHANUTE AND SALINA POSSIBLY SETTING NEW RECORDS FOR THE DATE. SOUTH WINDS WILL ALSO PICK UP IN THE WARM SECTOR THIS AFTERNOON THOUGH SHOULD REMAIN BELOW WIND ADVISORY LEVELS. THE WARM/MOIST SOUTHERLY FLOW WILL RESULT IN MODEST INSTABILITY ACROSS SOUTHEAST KANSAS BY THIS EVENING WHERE DEEP LAYER SHEAR PROFILES WILL ALSO INCREASE. IF CONVECTION CAN DEVELOP A FEW STRONG TO MARGINALLY SEVERE STORMS WILL BE POSSIBLE. BROAD SCALE FORCING FOR ASCENT WILL RESIDE ACROSS THE WARM/MOIST SECTOR ACROSS SOUTHEAST KANSAS ON TUESDAY AHEAD OF THE UPPER TROF. WILL CONTINUE TO HIGHLIGHT SLIGHT RISK FOR SEVERE STORMS THOUGH LATEST FRONTAL TIMING WOULD SUGGEST BETTER CHANCES WILL SHIFT EAST OF THE AREA BY LATE AFTERNOON OR EARLY EVENING. SOME LIGHT POST-FRONTAL PRECIP IS POSSIBLE TUESDAY EVENING MAINLY ACROSS CENTRAL KANSAS...THOUGH GENERALLY TRACE SPRINKLES TO FLURRIES. WEDNESDAY BACK TO SEASONABLY COLD AIR FOR MID-WEEK AS THE MEAN UPPER TROF SHIFTS EAST FROM THE PLAINS ACROSS THE MIDWEST. LITTLE CHANGE TO THE FORECAST WITH DRY WEATHER. THURSDAY-SUNDAY ADDITIONAL SHORTWAVE TROFS WILL ROTATE THROUGH THE EASTERN CONUS LONGWAVE...HELPING TO REINFORCE THE CHILLY AIR ACROSS THE PLAINS ON THURSDAY...WITH GRADUAL TEMPERATURE MODERATION EXPECTED BY THE WEEKEND. DARMOFAL && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 73 48 57 25 / 10 10 10 10 HUTCHINSON 73 43 52 23 / 10 10 10 10 NEWTON 72 46 53 23 / 10 10 10 10 ELDORADO 71 50 58 26 / 10 10 10 10 WINFIELD-KWLD 74 52 63 27 / 10 10 10 10 RUSSELL 69 35 43 20 / 10 10 10 10 GREAT BEND 71 37 44 20 / 10 10 10 10 SALINA 70 40 47 22 / 10 10 10 10 MCPHERSON 72 42 50 22 / 10 10 10 10 COFFEYVILLE 73 59 67 32 / 10 30 60 10 CHANUTE 73 57 63 29 / 10 30 50 10 IOLA 73 57 63 28 / 10 30 50 10 PARSONS-KPPF 73 58 65 30 / 10 30 60 10 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1144 AM CST MON JAN 28 2013 ...UPDATED FOR AVIATION... .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 313 AM CST MON JAN 28 2013 THE BIGGEST CHALLENGE TO THIS FORECAST IS HOW FAR SOUTHWEST WILL ANY DENSE FOG DEVELOP. THE SITES OF HLC, RSL, ICT, AND MCK HAVE ALL ALREADY BEEN DOWN TO 1/4SM IN DENSE FOG THIS MORNING. HYS HAS FLIRTED WITH 1SM AND GBD IS DOWN TO 3SM AT 08Z. THE RUC AND HRRR SHORT TERM MODELS ARE STRONG WITH FORECASTING LESS THAN A QUARTER OF A MILE FROM NEAR SCOTT CITY DOWN TO PRATT. HAVE DECIDED TO GO WITH AN NPW DENSE FOG ADVISORY FOR THIS AREA, UNTIL ABOUT 17Z. WINDS WILL CONTINUE TO BE LIGHT AND VARIABLE UNTIL ABOUT 17Z, THEN WILL GRADUALLY BECOME SOUTH OR SOUTHWEST AT 15 MPH GUSTING TO 20 MPH IN THE NPW AREA. THIS SHOULD DISSIPATE THE FOG RAPIDLY. AS WINDS BECOME STRONGER ACROSS SOUTHWEST KANSAS BY 18Z, GENERALLY IN THE 20G30MPH RANGE, WARM AIR JUST ABOVE THE SURFACE WILL MIX DOWN. AT 850MB, THE DDC TEMP AT 00Z WAS 3C WARMER THAN YESTERDAY, AND WAS AT +13C. A SWATH OF +14C AIR WAS OVER THE SOUTHERN TIER OF COUNTIES NEAR THE OKLAHOMA BORDER. THUS, I THINK HIGHS WILL REACH LEVELS SIMILAR TO YESTERDAY ALONG THE OKLAHOMA BORDER, WHERE A RECORD HIGH WAS SET AT P28 AT 74F. THE AREAS IN THE NORTH AND NORTHEAST, WHICH WILL HAVE A DELAYED PERIOD FOR HEATING DUE TO LOW CLOUDS AND FOG THIS MORNING, SHOULD ONLY SEE HIGHS IN THE UPPER 60S. AS FOR TONIGHT, THE WINDS WILL STAY IN THE 10 TO 15 MPH RANGE THROUGH ABOUT MIDNIGHT, THEN WILL DROP TO AROUND 10 MPH. A PRE-FRONTAL TROUGH WILL SLIDE THROUGH TO THE SOUTHEAST AND SWITCH WINDS TO THE NORTH AT 10 TO 15 MPH, FIRST IN THE SCOTT CITY AREA AND A LITTLE LATER IN THE GARDEN CITY AND DODGE CITY AREAS. COOL AIR WILL DROP INTO THE AREA NORTHWEST OF A LIBERAL TO DODGE CITY TO LA CROSSE LINE LATE TONIGHT. MINIMUMS THERE WILL AVERAGE IN THE UPPER 20S TO LOWER 30S. THE PRE-FRONTAL TROUGH WILL NOT REACH THE PRATT, MEDICINE LODGE AND COLDWATER AREAS PRIOR TO 12Z TUESDAY, SO MINIMUMS IN THOSE AREAS WILL STAY ELEVATED IN THE MID 40S. SOME HIGH CLOUDS WILL MOVE IN BEHIND THE WIND SHIFT, BUT SHOULD NOT BE THICK ENOUGH TO HAVE MUCH INFLUENCE ON THE MINIMUM TEMPERATURES. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 301 AM CST MON JAN 28 2013 MEDIUM RANGE MODELS INDICATE A STRONG UPPER LEVEL TROUGH OF LOW PRESSURE TRACKING EASTWARD ACROSS THE WESTERN HIGH PLAINS TUESDAY BRINGING THE POSSIBILITY FOR PRECIP GENERALLY FROM THE NORTHERN PLAINS SOUTHWARD INTO CENTRAL AND EAST TEXAS. AN ATTENDANT COLD FRONT IS PROJECTED TO PUSH THROUGH WESTERN KANSAS EARLY TUESDAY MORNING PROVIDING THE FOCUS FOR INCREASED LIFT NEAR THE SURFACE. HOWEVER, A STRONG SOUTHWESTERLY LOW LEVEL FLOW ACROSS ALL OF CENTRAL AND SOUTHWEST KANSAS MONDAY WILL KEEP A VAST POOL OF GULF MOISTURE BLOCKED OFF TO OUR EAST AND SOUTHEAST FROM EAST TEXAS NORTHEAST INTO MISSOURI. THIS WILL HINDER PRECIP CHANCES ACROSS WESTERN KANSAS TUESDAY. STILL, STRONG FAVORABLE DYNAMICS ALOFT COMBINED WITH JUST ENOUGH MID LEVEL MOISTURE MAY SUPPORT A FEW FLURRIES ACROSS PORTIONS OF WESTERN KANSAS TUESDAY AFTERNOON. DRIER CONDITIONS ARE LIKELY THROUGH THE END OF THE WEEK AS THE UPPER LEVEL TROUGH KICKS OFF TO THE EAST WHILE UPPER LEVEL RIDGING BEGINS TO TAKE HOLD IN THE INTERMOUNTAIN WEST LATE IN THE PERIOD. COOLER TEMPERATURES ARE LIKELY TUESDAY AS A STRONG COLD FRONT PUSHES THROUGH WESTERN KANSAS BY EARLY AFTERNOON. COLDER AIR WILL SURGE SOUTHWARD INTO WESTERN KANSAS BEHIND THE FRONT DROPPING H85 TEMPERATURES TO JUST BELOW 0C AS THE BOUNDARY MOVES THROUGH. ALTHOUGH THERE IS STILL UNCERTAINTY AS IT PERTAINS TO THE TIMING OF THE BOUNDARY PASSAGE, IT APPEARS HIGHS WILL BE REACHED BY MID TO LATE MORNING ACROSS WEST CENTRAL KANSAS WHILE HIGHS ARE REACHED IN SOUTH CENTRAL KANSAS BY EARLY TO MID AFTERNOON. AGAIN, TIMING OF THE FRONT WILL BE KEY, BUT LOOK FOR HIGHS GENERALLY UP INTO THE 40S(F) WITH THE LOWER TO MID 50S(F) STILL POSSIBLE IN SOUTH CENTRAL KANSAS JUST AHEAD OF THE FRONT. TEMPERATURES WILL REMAIN FAIRLY COLD WEDNESDAY AS ARCTIC AIR ASSOCIATED WITH A SURFACE HIGH IN THE NORTHERN PLAINS SPILLS SOUTH INTO THE CENTRAL PLAINS WITH H85 TEMPERATURES NEARING 10C BELOW ACROSS CENTRAL KANSAS NEAR THE I-70 CORRIDOR. THE GEM, GFS, AND ECMWF SHOW H85 TEMPERATURES CLOSER TO 0C IN EXTREME SOUTHWESTERN KANSAS. HIGHS MAY STRUGGLE TO REACH THE 30S(F) ACROSS CENTRAL KANSAS WEDNESDAY AFTERNOON WITH THE LOWER TO MID 40S(F) EXPECTED IN FAR SOUTHWEST KANSAS. A GRADUAL WARMING TREND IS THEN LIKELY THROUGH THE END OF THE WEEK AS UPPER LEVEL RIDGING BEGINS TO DEVELOP IN THE INTERMOUNTAIN WEST LATE IN THE PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1142 AM CST MON JAN 28 2013 BOUNDARY LAYER WARMING AND SUBSEQUENT MIXING HAS ERODED THE FOG AND STRATUS LAYER NORTHWARD ACROSS THE AREA THIS MORNING. AS A RESULT, CEILINGS OR RESTRICTIVE VISIBILITIES WILL NO LONGER BE AN ISSUE FOR ANY OF THE SOUTHWEST KANSAS TERMINAL SITES. A COLD FRONT WILL MOVE INTO WESTERN KANSAS BETWEEN 07 AND 10 UTC TUESDAY, TURNING WINDS NORTHWEST. && .PRELIMINARY POINT TEMPS/POPS... DDC 71 33 43 21 / 0 0 10 10 GCK 71 30 42 20 / 0 0 20 10 EHA 69 32 41 21 / 0 0 20 10 LBL 71 32 43 22 / 0 0 10 10 HYS 68 32 43 20 / 0 10 10 10 P28 75 44 55 24 / 0 0 10 10 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...BURKE LONG TERM...JJOHNSON AVIATION...RUSSELL
AREA FORECAST DISCUSSION
NWS GOODLAND KS
942 AM MST MON JAN 28 2013 .UPDATE... ISSUED AT 940 AM MST MON JAN 28 2013 CLEARED WESTERN COUNTIES FROM DENSE FOG ADVISORY. THE REMAINING COUNTIES WILL SEE IMPROVEMENT IN THE NEXT HOUR OR TWO FROM WEST TO EAST. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 401 AM MST MON JAN 28 2013 ONCE AGAIN THERE ARE NUMEROUS FORECAST PROBLEMS TO ADDRESS THROUGH THE SHORT TERM. SATELLITE SHOWING A COMPLICATED AND AMPLIFIED FLOW FROM THE PACIFIC INTO WESTERN NORTH AMERICA. RATHER STRONG/COLD AND POSITIVELY TILTED TROUGH IS APPROACHING FROM THE WEST THIS MORNING. COOL AND MOIST AIR MASS OVER THE AREA THIS MORNING IS EXPECTED TO GIVE WAY TO A WARMER AIR MASS THAT IS NOT TOO FAR AWAY. AT JET LEVEL...THE ECMWF AND CANADIAN WERE DOING A LITTLE BETTER THAN THE OTHERS WITH THE JET SEGMENT THAT IS GETTING CLOSER TO US. THAT OUTPUT WAS A LITTLE TOO FAR EAST. MODELS INITIALIZED WELL AT MID LEVELS. AT THE SURFACE...THE MODELS TENDED TO HAVE THE FRONT TO OUR SOUTH AND THE SURFACE TROUGH TO OUR WEST...TO FAR NORTH AND EAST. THE SREF WAS DOING A LITTLE BETTER THAN THE ECMWF AND NAM. THE RUC AND HRRR ARE CATCHING THE FOG WITH THE NAM NOT HAVING A CLUE ABOUT IT LIKE LAST NIGHT. THE SREF IS DOING BEST ON THE LOW LEVEL THERMAL FIELD AND IS A LITTLE BETTER THAN THE UKMET...ECMWF...AND GFS. TODAY/TONIGHT...FIRST CONCERN WHICH THE EVENING SHIFT ALREADY ADDRESSED HAS BEEN DENSE FOG. WILL CONTINUE TO MONITOR TRENDS. AT THIS TIME WILL KEEP THE CURRENT AREA OF THE ADVISORY BUT THERE ARE INDICATIONS THAT THE ADVISORY MAY NEED TO BE EXPANDED. BIG KEYS ON THE MAX TEMPERATURES IS HOW FAST THE STRATUS/FOG RETREATS/ENDS AND WHEN THE COLD FRONT LOOKS TO START MOVING IN THE NORTH. THE MODELS ARE SLOWER WITH THE FRONT. RUC/HRRR HAVE A GOOD HANDLE ON THE STRATUS/FOG AREA. IT LOOKS LIKE THE FAR NORTHEAST CORNER COULD NOT CLEAR UNTIL LATER THIS AFTERNOON. IF THAT IS THE CASE...THE TEMPERATURES I HAVE UP THERE WILL BE TOO WARM. SUFFICE TO SAY THERE COULD BE A HUGE GRADIENT IN TEMPERATURES TODAY. AND IF THAT IS NOT BAD ENOUGH...SOME MID AND HIGH LEVEL CLOUD COVER WILL START INCREASE IN THE WEST IN THE AFTERNOON. COMPARING THE RUC/HRRR TO THE BETTER 850 MB TEMPERATURE GUIDANCE WOULD SUPPORT 60S OVER AREAS THAT GET A LOT OF SUN...MAYBE EVEN 70 DEGREE READING. AS SURFACE RIDGE MOVES AWAY AND SURFACE LOW OVER EASTERN STRENGTHENS...GRADIENT IS EXPECTED TO TIGHTEN ALONG WITH MODERATE 3 HOUR PRESSURE FALLS. SO OVER THE SOUTHWEST PORTION OF THE AREA IT COULD GET BREEZY TO WINDY. THIS MAY CAUSE SOME FIRE WEATHER ISSUES. REFER TO THE FIRE WEATHER SECTION BELOW. BY LATE AFTERNOON...THE RIGHT REAR QUADRANT OF THE JET WILL BE AFFECTING THE SOUTHEAST HALF OF THE AREA. BY LATE EVENING THIS HAS MOVED EAST OF THE AREA. THIS JET LIFT IS OUT OF PHASE WITH THE DEEPER MOISTURE AND OTHER LIFT. AT THIS TIME ONLY EXPECT CLOUDS IN THE AFTERNOON FOR MOST OF THE AREA THIS AFTERNOON. AFTER THAT...ABOVE MENTIONED UPPER TROUGH...WITH RATHER COLD AIR ALOFT...IS EXPECTED TO START MOVE THROUGH DURING THE NIGHT. ON THE SOUTHERN END OF THIS TROUGH SPORADIC LIGHTNING STRIKES HAVE BEEN DETECTED. AM CONCERNED THIS SYSTEM IS COMING IN A LITTLE STRONGER THAN 00Z MODELS SHOWED DESPITE BEING AN OPEN WAVE AND MOVING THROUGH RATHER QUICKLY. NEWER DATA COME IN WITH A LITTLE BETTER MOISTURE PROFILE. AT THIS TIME THE NORTHWEST PORTION OF THE AREA CAME IN WITH THE BEST MOISTURE...INSTABILITY...AND LIFT SETUP. SO MADE THE HIGHEST POPS IN THERE DURING THE NIGHT. THE BEST PARAMETERS DO NOT REALLY START COMING INTO THE AREA UNTIL LATE IN THE EVENING. GRADIENT AND 3 HOUR PRESSURE RISES SUPPORT BREEZY TO MAYBE WINDY BEHIND THE FRONT. TUESDAY/TUESDAY NIGHT...TROUGH IS STILL TO THE WEST OF THE AREA AT 12Z WITH A RATHER STRONG PV ANOMALY INDICATED WITH IT. TROUGH/ANOMALY MOVE ACROSS DURING THE DAY. DESPITE WHAT APPEARS NOT THE BEST OF MOISTURE PROFILES...THE INSTABILITY AND STRENGTH OF THIS SYSTEM HAS ME CONCERNED ABOUT MEASURABLE SNOW/PRECIPITATION. SO RAISED POPS INTO THE 20 TO 30 PERCENT RANGE BUT COULD SEE THE POSSIBILITY OF NEEDING HIGHER POPS. ALSO IF THERE ENDS UP BEING MORE SNOW THAN I THINK...THERE COULD BE SOME BLOWING SNOW DUE TO THE STRONG AND GUSTY WINDS. IT IS POSSIBLE THAT THE WINDS COULD GET CLOSE TO WIND ADVISORY CRITERIA. MODELS ARE COMING IN COLDER AND MORE EXTENSIVE CLOUD COVER. SO REDUCED MAXES AND IF THE COLDER MODELS WORK OUT...I MAY BE TOO WARM. ANOTHER SHORTWAVE TROUGH...WEAK JET LIFT AND A REINFORCING SHORT OF COLD AIR COULD KEEP FLURRIES GOING THROUGH THE NIGHT. WEDNESDAY/WEDNESDAY NIGHT...SO HOW COLD DOES IT REMAIN BEHIND EXITING SYSTEM. MODELS IN GOOD AGREEMENT IN BRINGING IN MUCH COLDER ONCE THE TROUGH HAS MOVED TO THE EAST. ALSO AN INDICATION THAT THERE MAY BE MORE CLOUD COVER THAN INDICATED. SO LOWERED MAXES AGAIN. AGAIN WITH STRONG CYCLONIC FLOW WITH EMBEDDED SHORTWAVES...FLURRIES COULD BE A POSSIBILITY. THIS FLURRY ACTIVITY ENDS DURING THE EVENING. .LONG TERM...(THURSDAY THROUGH SUNDAY) ISSUED AT 253 AM MST MON JAN 28 2013 MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD. THE LARGE UPPER LEVEL TROUGH ACROSS THE CENTRAL AND EASTERN UNITED STATES WILL CONTINUE MOVING SLOWLY TO THE EAST AND AN UPPER LEVEL RIDGE OF HIGH PRESSURE SHOULD BUILD IN FROM THE WEST TOWARDS THE END OF THE WEEK. A SURFACE HIGH PRESSURE WILL ALSO BECOME A PERSISTENT FEATURE ACROSS THE PLAINS. WITH A RIDGE OF HIGH PRESSURE BUILDING IN AND PERSISTENT SURFACE HIGH...PRECIPITATION CHANCES THROUGH MOST OF THE EXTENDED FORECAST APPEAR MINIMAL. THE ONLY CHANCE WOULD BE ON THURSDAY AS A WEAK SHORTWAVE ROTATES AROUND THE EDGE OF THE UPPER LEVEL TROUGH. MODELS HAVE BACKED OFF ON THE COVERAGE AND QPF AMOUNTS ACROSS THE TRI-STATE AREA SO HAVE MADE CHANGES IN THE FORECAST TO REFLECT THIS. AT THE PRESENT TIME...NO PRECIPITATION IS MENTIONED. THE TRICKY PORTION OF THE EXTENDED FORECAST CONCERNS THE HIGH TEMPERATURES. ON THURSDAY...MODELS INDICATE A TIGHT TEMPERATURE GRADIENT ACROSS THE REGION AS THE COLD FRONT THAT MOVES THROUGH ON MONDAY NIGHT LINGERS. THERE ARE SLIGHT DIFFERENCES IN THE GRADIENT LOCATION BETWEEN THE GFS...CANADIAN AND EUROPEAN MODELS. THE GFS IS COOLER THAN THE EUROPEAN SOLUTION BY 7 TO 8 DEGREES AS A RESULT. FOR FRIDAY THROUGH SUNDAY...A WARMING TREND IS EXPECTED AS ALL MODELS SHOW TEMPERATURES AT 850 MB WARMING. MODELS ARE IN BETTER AGREEMENT IN THIS TIME FRAME WITH GUIDANCE WITHIN A FEW DEGREES EACH DAY. THE GENERAL PATTERN THAT MODELS ARE PROJECTING IS VERY SIMILAR TO THE WARM SCENARIO THAT PLAYED OUT LAST WEEK. RAISED HIGH TEMPERATURES EACH DAY AS A RESULT OF LAST WEEKS WEATHER AND CONTINUED DROUGHT CONDITIONS. BOTH THE GFS AND EUROPEAN MODELS SHOW 850 MB TEMPERATURES CREEPING UP TO 10 DEGREES CELSIUS FOR SUNDAY...SO HAVE MADE SUNDAY THE WARMEST DAY IN THE EXTENDED WITH HIGHS APPROACHING 60 FOR MOST OF THE REGION. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 456 AM MST MON JAN 28 2013 HRRR CONTINUES TO HANDLE STRATUS AND FOG FIELD VERY WELL. FOR KGLD...IT LOOKS LIKE IFR/LIFR CONDITIONS WILL STAY TO THE EAST OF THE SITE THIS MORNING. KGLD MAY GET SOME BRIEF CONDITIONS BEFORE IMPROVING BY MID MORNING. OTHERWISE AT KGLD...AN UPPER LEVEL STORM SYSTEM AND ASSOCIATED COLD FRONT WILL MOVE INTO THE AREA TONIGHT. THIS WILL SPREAD MVFR AND POSSIBLE IFR CONDITIONS INTO THE AREA BEGINNING AROUND 04Z. MAY BE SOME SNOW AROUND HOWEVER CHOSE TO HANDLE WITH VCSH SINCE TOWARD THE END OF THE PERIOD. FOR KMCK...LIFR CONDITIONS WILL LAST THROUGH LATE MORNING BEFORE IMPROVEMENT. IT IS POSSIBLE IFR/MVFR CONDITIONS COULD LAST A FEW HOURS BEYOND THIS BUT LATER SHIFTS CAN ADDRESS WHEN IT BECOMES MORE CLEAR. STORM SYSTEM AND COLD FRONT MOVE INTO THE AREA LATER THIS EVENING. THIS WILL BRING IFR TO MVFR CEILINGS BACK TO THE AREA WITH LIGHT SNOW SHOWERS POSSIBLE AS WELL. && .FIRE WEATHER... ISSUED AT 401 AM MST MON JAN 28 2013 THE SOUTHWEST PORTION...ESPECIALLY FAR WESTERN CHEYENNE AND KIT CARSON COULD REACH CRITICAL FIRE WEATHER CONDITIONS. AT THIS TIME IT LOOKS LIKE THE RELATIVE HUMIDITIES STAY ABOVE 20 PERCENT WITH ADEQUATE WINDS NOT LASTING THREE HOURS. SO ISSUED NO HIGHLIGHT FOR THIS. BUT DAY SHIFT WILL NEED TO WATCH THIS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR KSZ002>004-014>016- 028-029. CO...NONE. NE...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR NEZ080-081. && $$ UPDATE...024 SHORT TERM...BULLER LONG TERM...RRH AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
738 AM MST MON JAN 28 2013 .UPDATE... ISSUED AT 737 AM MST MON JAN 28 2013 1/4 MILE VISIBILITY REPORTED IN TRIBUNE...23SW OF GOODLAND...AND BY COOP OBSERVERS IN CHEYENNE COUNTY COLORADO. ADDED THOSE COUNTIES TO THE ONGOING DENSE FOG ADVISORY. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 401 AM MST MON JAN 28 2013 ONCE AGAIN THERE ARE NUMEROUS FORECAST PROBLEMS TO ADDRESS THROUGH THE SHORT TERM. SATELLITE SHOWING A COMPLICATED AND AMPLIFIED FLOW FROM THE PACIFIC INTO WESTERN NORTH AMERICA. RATHER STRONG/COLD AND POSITIVELY TILTED TROUGH IS APPROACHING FROM THE WEST THIS MORNING. COOL AND MOIST AIR MASS OVER THE AREA THIS MORNING IS EXPECTED TO GIVE WAY TO A WARMER AIR MASS THAT IS NOT TOO FAR AWAY. AT JET LEVEL...THE ECMWF AND CANADIAN WERE DOING A LITTLE BETTER THAN THE OTHERS WITH THE JET SEGMENT THAT IS GETTING CLOSER TO US. THAT OUTPUT WAS A LITTLE TOO FAR EAST. MODELS INITIALIZED WELL AT MID LEVELS. AT THE SURFACE...THE MODELS TENDED TO HAVE THE FRONT TO OUR SOUTH AND THE SURFACE TROUGH TO OUR WEST...TO FAR NORTH AND EAST. THE SREF WAS DOING A LITTLE BETTER THAN THE ECMWF AND NAM. THE RUC AND HRRR ARE CATCHING THE FOG WITH THE NAM NOT HAVING A CLUE ABOUT IT LIKE LAST NIGHT. THE SREF IS DOING BEST ON THE LOW LEVEL THERMAL FIELD AND IS A LITTLE BETTER THAN THE UKMET...ECMWF...AND GFS. TODAY/TONIGHT...FIRST CONCERN WHICH THE EVENING SHIFT ALREADY ADDRESSED HAS BEEN DENSE FOG. WILL CONTINUE TO MONITOR TRENDS. AT THIS TIME WILL KEEP THE CURRENT AREA OF THE ADVISORY BUT THERE ARE INDICATIONS THAT THE ADVISORY MAY NEED TO BE EXPANDED. BIG KEYS ON THE MAX TEMPERATURES IS HOW FAST THE STRATUS/FOG RETREATS/ENDS AND WHEN THE COLD FRONT LOOKS TO START MOVING IN THE NORTH. THE MODELS ARE SLOWER WITH THE FRONT. RUC/HRRR HAVE A GOOD HANDLE ON THE STRATUS/FOG AREA. IT LOOKS LIKE THE FAR NORTHEAST CORNER COULD NOT CLEAR UNTIL LATER THIS AFTERNOON. IF THAT IS THE CASE...THE TEMPERATURES I HAVE UP THERE WILL BE TOO WARM. SUFFICE TO SAY THERE COULD BE A HUGE GRADIENT IN TEMPERATURES TODAY. AND IF THAT IS NOT BAD ENOUGH...SOME MID AND HIGH LEVEL CLOUD COVER WILL START INCREASE IN THE WEST IN THE AFTERNOON. COMPARING THE RUC/HRRR TO THE BETTER 850 MB TEMPERATURE GUIDANCE WOULD SUPPORT 60S OVER AREAS THAT GET A LOT OF SUN...MAYBE EVEN 70 DEGREE READING. AS SURFACE RIDGE MOVES AWAY AND SURFACE LOW OVER EASTERN STRENGTHENS...GRADIENT IS EXPECTED TO TIGHTEN ALONG WITH MODERATE 3 HOUR PRESSURE FALLS. SO OVER THE SOUTHWEST PORTION OF THE AREA IT COULD GET BREEZY TO WINDY. THIS MAY CAUSE SOME FIRE WEATHER ISSUES. REFER TO THE FIRE WEATHER SECTION BELOW. BY LATE AFTERNOON...THE RIGHT REAR QUADRANT OF THE JET WILL BE AFFECTING THE SOUTHEAST HALF OF THE AREA. BY LATE EVENING THIS HAS MOVED EAST OF THE AREA. THIS JET LIFT IS OUT OF PHASE WITH THE DEEPER MOISTURE AND OTHER LIFT. AT THIS TIME ONLY EXPECT CLOUDS IN THE AFTERNOON FOR MOST OF THE AREA THIS AFTERNOON. AFTER THAT...ABOVE MENTIONED UPPER TROUGH...WITH RATHER COLD AIR ALOFT...IS EXPECTED TO START MOVE THROUGH DURING THE NIGHT. ON THE SOUTHERN END OF THIS TROUGH SPORADIC LIGHTNING STRIKES HAVE BEEN DETECTED. AM CONCERNED THIS SYSTEM IS COMING IN A LITTLE STRONGER THAN 00Z MODELS SHOWED DESPITE BEING AN OPEN WAVE AND MOVING THROUGH RATHER QUICKLY. NEWER DATA COME IN WITH A LITTLE BETTER MOISTURE PROFILE. AT THIS TIME THE NORTHWEST PORTION OF THE AREA CAME IN WITH THE BEST MOISTURE...INSTABILITY...AND LIFT SETUP. SO MADE THE HIGHEST POPS IN THERE DURING THE NIGHT. THE BEST PARAMETERS DO NOT REALLY START COMING INTO THE AREA UNTIL LATE IN THE EVENING. GRADIENT AND 3 HOUR PRESSURE RISES SUPPORT BREEZY TO MAYBE WINDY BEHIND THE FRONT. TUESDAY/TUESDAY NIGHT...TROUGH IS STILL TO THE WEST OF THE AREA AT 12Z WITH A RATHER STRONG PV ANOMALY INDICATED WITH IT. TROUGH/ANOMALY MOVE ACROSS DURING THE DAY. DESPITE WHAT APPEARS NOT THE BEST OF MOISTURE PROFILES...THE INSTABILITY AND STRENGTH OF THIS SYSTEM HAS ME CONCERNED ABOUT MEASURABLE SNOW/PRECIPITATION. SO RAISED POPS INTO THE 20 TO 30 PERCENT RANGE BUT COULD SEE THE POSSIBILITY OF NEEDING HIGHER POPS. ALSO IF THERE ENDS UP BEING MORE SNOW THAN I THINK...THERE COULD BE SOME BLOWING SNOW DUE TO THE STRONG AND GUSTY WINDS. IT IS POSSIBLE THAT THE WINDS COULD GET CLOSE TO WIND ADVISORY CRITERIA. MODELS ARE COMING IN COLDER AND MORE EXTENSIVE CLOUD COVER. SO REDUCED MAXES AND IF THE COLDER MODELS WORK OUT...I MAY BE TOO WARM. ANOTHER SHORTWAVE TROUGH...WEAK JET LIFT AND A REINFORCING SHORT OF COLD AIR COULD KEEP FLURRIES GOING THROUGH THE NIGHT. WEDNESDAY/WEDNESDAY NIGHT...SO HOW COLD DOES IT REMAIN BEHIND EXITING SYSTEM. MODELS IN GOOD AGREEMENT IN BRINGING IN MUCH COLDER ONCE THE TROUGH HAS MOVED TO THE EAST. ALSO AN INDICATION THAT THERE MAY BE MORE CLOUD COVER THAN INDICATED. SO LOWERED MAXES AGAIN. AGAIN WITH STRONG CYCLONIC FLOW WITH EMBEDDED SHORTWAVES...FLURRIES COULD BE A POSSIBILITY. THIS FLURRY ACTIVITY ENDS DURING THE EVENING. .LONG TERM...(THURSDAY THROUGH SUNDAY) ISSUED AT 253 AM MST MON JAN 28 2013 MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD. THE LARGE UPPER LEVEL TROUGH ACROSS THE CENTRAL AND EASTERN UNITED STATES WILL CONTINUE MOVING SLOWLY TO THE EAST AND AN UPPER LEVEL RIDGE OF HIGH PRESSURE SHOULD BUILD IN FROM THE WEST TOWARDS THE END OF THE WEEK. A SURFACE HIGH PRESSURE WILL ALSO BECOME A PERSISTENT FEATURE ACROSS THE PLAINS. WITH A RIDGE OF HIGH PRESSURE BUILDING IN AND PERSISTENT SURFACE HIGH...PRECIPITATION CHANCES THROUGH MOST OF THE EXTENDED FORECAST APPEAR MINIMAL. THE ONLY CHANCE WOULD BE ON THURSDAY AS A WEAK SHORTWAVE ROTATES AROUND THE EDGE OF THE UPPER LEVEL TROUGH. MODELS HAVE BACKED OFF ON THE COVERAGE AND QPF AMOUNTS ACROSS THE TRI-STATE AREA SO HAVE MADE CHANGES IN THE FORECAST TO REFLECT THIS. AT THE PRESENT TIME...NO PRECIPITATION IS MENTIONED. THE TRICKY PORTION OF THE EXTENDED FORECAST CONCERNS THE HIGH TEMPERATURES. ON THURSDAY...MODELS INDICATE A TIGHT TEMPERATURE GRADIENT ACROSS THE REGION AS THE COLD FRONT THAT MOVES THROUGH ON MONDAY NIGHT LINGERS. THERE ARE SLIGHT DIFFERENCES IN THE GRADIENT LOCATION BETWEEN THE GFS...CANADIAN AND EUROPEAN MODELS. THE GFS IS COOLER THAN THE EUROPEAN SOLUTION BY 7 TO 8 DEGREES AS A RESULT. FOR FRIDAY THROUGH SUNDAY...A WARMING TREND IS EXPECTED AS ALL MODELS SHOW TEMPERATURES AT 850 MB WARMING. MODELS ARE IN BETTER AGREEMENT IN THIS TIME FRAME WITH GUIDANCE WITHIN A FEW DEGREES EACH DAY. THE GENERAL PATTERN THAT MODELS ARE PROJECTING IS VERY SIMILAR TO THE WARM SCENARIO THAT PLAYED OUT LAST WEEK. RAISED HIGH TEMPERATURES EACH DAY AS A RESULT OF LAST WEEKS WEATHER AND CONTINUED DROUGHT CONDITIONS. BOTH THE GFS AND EUROPEAN MODELS SHOW 850 MB TEMPERATURES CREEPING UP TO 10 DEGREES CELSIUS FOR SUNDAY...SO HAVE MADE SUNDAY THE WARMEST DAY IN THE EXTENDED WITH HIGHS APPROACHING 60 FOR MOST OF THE REGION. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 456 AM MST MON JAN 28 2013 HRRR CONTINUES TO HANDLE STRATUS AND FOG FIELD VERY WELL. FOR KGLD...IT LOOKS LIKE IFR/LIFR CONDITIONS WILL STAY TO THE EAST OF THE SITE THIS MORNING. KGLD MAY GET SOME BRIEF CONDITIONS BEFORE IMPROVING BY MID MORNING. OTHERWISE AT KGLD...AN UPPER LEVEL STORM SYSTEM AND ASSOCIATED COLD FRONT WILL MOVE INTO THE AREA TONIGHT. THIS WILL SPREAD MVFR AND POSSIBLE IFR CONDITIONS INTO THE AREA BEGINNING AROUND 04Z. MAY BE SOME SNOW AROUND HOWEVER CHOSE TO HANDLE WITH VCSH SINCE TOWARD THE END OF THE PERIOD. FOR KMCK...LIFR CONDITIONS WILL LAST THROUGH LATE MORNING BEFORE IMPROVEMENT. IT IS POSSIBLE IFR/MVFR CONDITIONS COULD LAST A FEW HOURS BEYOND THIS BUT LATER SHIFTS CAN ADDRESS WHEN IT BECOMES MORE CLEAR. STORM SYSTEM AND COLD FRONT MOVE INTO THE AREA LATER THIS EVENING. THIS WILL BRING IFR TO MVFR CEILINGS BACK TO THE AREA WITH LIGHT SNOW SHOWERS POSSIBLE AS WELL. && .FIRE WEATHER... ISSUED AT 401 AM MST MON JAN 28 2013 THE SOUTHWEST PORTION...ESPECIALLY FAR WESTERN CHEYENNE AND KIT CARSON COULD REACH CRITICAL FIRE WEATHER CONDITIONS. AT THIS TIME IT LOOKS LIKE THE RELATIVE HUMIDITIES STAY ABOVE 20 PERCENT WITH ADEQUATE WINDS NOT LASTING THREE HOURS. SO ISSUED NO HIGHLIGHT FOR THIS. BUT DAY SHIFT WILL NEED TO WATCH THIS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL 11 AM MST /NOON CST/ THIS MORNING FOR KSZ002>004-013>016-027>029-041-042. CO...DENSE FOG ADVISORY UNTIL 11 AM MST THIS MORNING FOR COZ092. NE...DENSE FOG ADVISORY UNTIL 11 AM MST /NOON CST/ THIS MORNING FOR NEZ079>081. && $$ UPDATE...024 SHORT TERM...BULLER LONG TERM...RRH AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
730 AM MST MON JAN 28 2013 .UPDATE... ISSUED AT 729 AM MST MON JAN 28 2013 TRIBUNE IS SOCKED IN AT 1/4SM...SO ADDED GREELEY AND WICHITA COUNTIES TO THE DENSE FOG ADVISORY. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 401 AM MST MON JAN 28 2013 ONCE AGAIN THERE ARE NUMEROUS FORECAST PROBLEMS TO ADDRESS THROUGH THE SHORT TERM. SATELLITE SHOWING A COMPLICATED AND AMPLIFIED FLOW FROM THE PACIFIC INTO WESTERN NORTH AMERICA. RATHER STRONG/COLD AND POSITIVELY TILTED TROUGH IS APPROACHING FROM THE WEST THIS MORNING. COOL AND MOIST AIR MASS OVER THE AREA THIS MORNING IS EXPECTED TO GIVE WAY TO A WARMER AIR MASS THAT IS NOT TOO FAR AWAY. AT JET LEVEL...THE ECMWF AND CANADIAN WERE DOING A LITTLE BETTER THAN THE OTHERS WITH THE JET SEGMENT THAT IS GETTING CLOSER TO US. THAT OUTPUT WAS A LITTLE TOO FAR EAST. MODELS INITIALIZED WELL AT MID LEVELS. AT THE SURFACE...THE MODELS TENDED TO HAVE THE FRONT TO OUR SOUTH AND THE SURFACE TROUGH TO OUR WEST...TO FAR NORTH AND EAST. THE SREF WAS DOING A LITTLE BETTER THAN THE ECMWF AND NAM. THE RUC AND HRRR ARE CATCHING THE FOG WITH THE NAM NOT HAVING A CLUE ABOUT IT LIKE LAST NIGHT. THE SREF IS DOING BEST ON THE LOW LEVEL THERMAL FIELD AND IS A LITTLE BETTER THAN THE UKMET...ECMWF...AND GFS. TODAY/TONIGHT...FIRST CONCERN WHICH THE EVENING SHIFT ALREADY ADDRESSED HAS BEEN DENSE FOG. WILL CONTINUE TO MONITOR TRENDS. AT THIS TIME WILL KEEP THE CURRENT AREA OF THE ADVISORY BUT THERE ARE INDICATIONS THAT THE ADVISORY MAY NEED TO BE EXPANDED. BIG KEYS ON THE MAX TEMPERATURES IS HOW FAST THE STRATUS/FOG RETREATS/ENDS AND WHEN THE COLD FRONT LOOKS TO START MOVING IN THE NORTH. THE MODELS ARE SLOWER WITH THE FRONT. RUC/HRRR HAVE A GOOD HANDLE ON THE STRATUS/FOG AREA. IT LOOKS LIKE THE FAR NORTHEAST CORNER COULD NOT CLEAR UNTIL LATER THIS AFTERNOON. IF THAT IS THE CASE...THE TEMPERATURES I HAVE UP THERE WILL BE TOO WARM. SUFFICE TO SAY THERE COULD BE A HUGE GRADIENT IN TEMPERATURES TODAY. AND IF THAT IS NOT BAD ENOUGH...SOME MID AND HIGH LEVEL CLOUD COVER WILL START INCREASE IN THE WEST IN THE AFTERNOON. COMPARING THE RUC/HRRR TO THE BETTER 850 MB TEMPERATURE GUIDANCE WOULD SUPPORT 60S OVER AREAS THAT GET A LOT OF SUN...MAYBE EVEN 70 DEGREE READING. AS SURFACE RIDGE MOVES AWAY AND SURFACE LOW OVER EASTERN STRENGTHENS...GRADIENT IS EXPECTED TO TIGHTEN ALONG WITH MODERATE 3 HOUR PRESSURE FALLS. SO OVER THE SOUTHWEST PORTION OF THE AREA IT COULD GET BREEZY TO WINDY. THIS MAY CAUSE SOME FIRE WEATHER ISSUES. REFER TO THE FIRE WEATHER SECTION BELOW. BY LATE AFTERNOON...THE RIGHT REAR QUADRANT OF THE JET WILL BE AFFECTING THE SOUTHEAST HALF OF THE AREA. BY LATE EVENING THIS HAS MOVED EAST OF THE AREA. THIS JET LIFT IS OUT OF PHASE WITH THE DEEPER MOISTURE AND OTHER LIFT. AT THIS TIME ONLY EXPECT CLOUDS IN THE AFTERNOON FOR MOST OF THE AREA THIS AFTERNOON. AFTER THAT...ABOVE MENTIONED UPPER TROUGH...WITH RATHER COLD AIR ALOFT...IS EXPECTED TO START MOVE THROUGH DURING THE NIGHT. ON THE SOUTHERN END OF THIS TROUGH SPORADIC LIGHTNING STRIKES HAVE BEEN DETECTED. AM CONCERNED THIS SYSTEM IS COMING IN A LITTLE STRONGER THAN 00Z MODELS SHOWED DESPITE BEING AN OPEN WAVE AND MOVING THROUGH RATHER QUICKLY. NEWER DATA COME IN WITH A LITTLE BETTER MOISTURE PROFILE. AT THIS TIME THE NORTHWEST PORTION OF THE AREA CAME IN WITH THE BEST MOISTURE...INSTABILITY...AND LIFT SETUP. SO MADE THE HIGHEST POPS IN THERE DURING THE NIGHT. THE BEST PARAMETERS DO NOT REALLY START COMING INTO THE AREA UNTIL LATE IN THE EVENING. GRADIENT AND 3 HOUR PRESSURE RISES SUPPORT BREEZY TO MAYBE WINDY BEHIND THE FRONT. TUESDAY/TUESDAY NIGHT...TROUGH IS STILL TO THE WEST OF THE AREA AT 12Z WITH A RATHER STRONG PV ANOMALY INDICATED WITH IT. TROUGH/ANOMALY MOVE ACROSS DURING THE DAY. DESPITE WHAT APPEARS NOT THE BEST OF MOISTURE PROFILES...THE INSTABILITY AND STRENGTH OF THIS SYSTEM HAS ME CONCERNED ABOUT MEASURABLE SNOW/PRECIPITATION. SO RAISED POPS INTO THE 20 TO 30 PERCENT RANGE BUT COULD SEE THE POSSIBILITY OF NEEDING HIGHER POPS. ALSO IF THERE ENDS UP BEING MORE SNOW THAN I THINK...THERE COULD BE SOME BLOWING SNOW DUE TO THE STRONG AND GUSTY WINDS. IT IS POSSIBLE THAT THE WINDS COULD GET CLOSE TO WIND ADVISORY CRITERIA. MODELS ARE COMING IN COLDER AND MORE EXTENSIVE CLOUD COVER. SO REDUCED MAXES AND IF THE COLDER MODELS WORK OUT...I MAY BE TOO WARM. ANOTHER SHORTWAVE TROUGH...WEAK JET LIFT AND A REINFORCING SHORT OF COLD AIR COULD KEEP FLURRIES GOING THROUGH THE NIGHT. WEDNESDAY/WEDNESDAY NIGHT...SO HOW COLD DOES IT REMAIN BEHIND EXITING SYSTEM. MODELS IN GOOD AGREEMENT IN BRINGING IN MUCH COLDER ONCE THE TROUGH HAS MOVED TO THE EAST. ALSO AN INDICATION THAT THERE MAY BE MORE CLOUD COVER THAN INDICATED. SO LOWERED MAXES AGAIN. AGAIN WITH STRONG CYCLONIC FLOW WITH EMBEDDED SHORTWAVES...FLURRIES COULD BE A POSSIBILITY. THIS FLURRY ACTIVITY ENDS DURING THE EVENING. .LONG TERM...(THURSDAY THROUGH SUNDAY) ISSUED AT 253 AM MST MON JAN 28 2013 MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD. THE LARGE UPPER LEVEL TROUGH ACROSS THE CENTRAL AND EASTERN UNITED STATES WILL CONTINUE MOVING SLOWLY TO THE EAST AND AN UPPER LEVEL RIDGE OF HIGH PRESSURE SHOULD BUILD IN FROM THE WEST TOWARDS THE END OF THE WEEK. A SURFACE HIGH PRESSURE WILL ALSO BECOME A PERSISTENT FEATURE ACROSS THE PLAINS. WITH A RIDGE OF HIGH PRESSURE BUILDING IN AND PERSISTENT SURFACE HIGH...PRECIPITATION CHANCES THROUGH MOST OF THE EXTENDED FORECAST APPEAR MINIMAL. THE ONLY CHANCE WOULD BE ON THURSDAY AS A WEAK SHORTWAVE ROTATES AROUND THE EDGE OF THE UPPER LEVEL TROUGH. MODELS HAVE BACKED OFF ON THE COVERAGE AND QPF AMOUNTS ACROSS THE TRI-STATE AREA SO HAVE MADE CHANGES IN THE FORECAST TO REFLECT THIS. AT THE PRESENT TIME...NO PRECIPITATION IS MENTIONED. THE TRICKY PORTION OF THE EXTENDED FORECAST CONCERNS THE HIGH TEMPERATURES. ON THURSDAY...MODELS INDICATE A TIGHT TEMPERATURE GRADIENT ACROSS THE REGION AS THE COLD FRONT THAT MOVES THROUGH ON MONDAY NIGHT LINGERS. THERE ARE SLIGHT DIFFERENCES IN THE GRADIENT LOCATION BETWEEN THE GFS...CANADIAN AND EUROPEAN MODELS. THE GFS IS COOLER THAN THE EUROPEAN SOLUTION BY 7 TO 8 DEGREES AS A RESULT. FOR FRIDAY THROUGH SUNDAY...A WARMING TREND IS EXPECTED AS ALL MODELS SHOW TEMPERATURES AT 850 MB WARMING. MODELS ARE IN BETTER AGREEMENT IN THIS TIME FRAME WITH GUIDANCE WITHIN A FEW DEGREES EACH DAY. THE GENERAL PATTERN THAT MODELS ARE PROJECTING IS VERY SIMILAR TO THE WARM SCENARIO THAT PLAYED OUT LAST WEEK. RAISED HIGH TEMPERATURES EACH DAY AS A RESULT OF LAST WEEKS WEATHER AND CONTINUED DROUGHT CONDITIONS. BOTH THE GFS AND EUROPEAN MODELS SHOW 850 MB TEMPERATURES CREEPING UP TO 10 DEGREES CELSIUS FOR SUNDAY...SO HAVE MADE SUNDAY THE WARMEST DAY IN THE EXTENDED WITH HIGHS APPROACHING 60 FOR MOST OF THE REGION. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 456 AM MST MON JAN 28 2013 HRRR CONTINUES TO HANDLE STRATUS AND FOG FIELD VERY WELL. FOR KGLD...IT LOOKS LIKE IFR/LIFR CONDITIONS WILL STAY TO THE EAST OF THE SITE THIS MORNING. KGLD MAY GET SOME BRIEF CONDITIONS BEFORE IMPROVING BY MID MORNING. OTHERWISE AT KGLD...AN UPPER LEVEL STORM SYSTEM AND ASSOCIATED COLD FRONT WILL MOVE INTO THE AREA TONIGHT. THIS WILL SPREAD MVFR AND POSSIBLE IFR CONDITIONS INTO THE AREA BEGINNING AROUND 04Z. MAY BE SOME SNOW AROUND HOWEVER CHOSE TO HANDLE WITH VCSH SINCE TOWARD THE END OF THE PERIOD. FOR KMCK...LIFR CONDITIONS WILL LAST THROUGH LATE MORNING BEFORE IMPROVEMENT. IT IS POSSIBLE IFR/MVFR CONDITIONS COULD LAST A FEW HOURS BEYOND THIS BUT LATER SHIFTS CAN ADDRESS WHEN IT BECOMES MORE CLEAR. STORM SYSTEM AND COLD FRONT MOVE INTO THE AREA LATER THIS EVENING. THIS WILL BRING IFR TO MVFR CEILINGS BACK TO THE AREA WITH LIGHT SNOW SHOWERS POSSIBLE AS WELL. && .FIRE WEATHER... ISSUED AT 401 AM MST MON JAN 28 2013 THE SOUTHWEST PORTION...ESPECIALLY FAR WESTERN CHEYENNE AND KIT CARSON COULD REACH CRITICAL FIRE WEATHER CONDITIONS. AT THIS TIME IT LOOKS LIKE THE RELATIVE HUMIDITIES STAY ABOVE 20 PERCENT WITH ADEQUATE WINDS NOT LASTING THREE HOURS. SO ISSUED NO HIGHLIGHT FOR THIS. BUT DAY SHIFT WILL NEED TO WATCH THIS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL 11 AM MST /NOON CST/ THIS MORNING FOR KSZ002>004-014>016-028-029-041-042. CO...NONE. NE...DENSE FOG ADVISORY UNTIL 11 AM MST /NOON CST/ THIS MORNING FOR NEZ079>081. && $$ UPDATE...024 SHORT TERM...BULLER LONG TERM...RRH AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
509 AM MST MON JAN 28 2013 .UPDATE... ISSUED AT 456 AM MST MON JAN 28 2013 HRRR CONTINUES TO HANDLE DENSE FOG AREA VERY WELL. CONSIDERING ITS TRENDS AND WHAT I AM SEEING IN THE OBSERVATIONS...WILL BE ADDING DUNDY TO THE DENSE FOG ADVISORY. SOMETHING TO DAY UPDATE GUY WILL NEED TO CONSIDER IS LOWERING MAXES IN THE FAR NORTH AND NORTHEAST IF STRATUS AND FOG ARE SLOWER TO ERODE THAN CURRENTLY EXPECT. && .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 401 AM MST MON JAN 28 2013 ONCE AGAIN THERE ARE NUMEROUS FORECAST PROBLEMS TO ADDRESS THROUGH THE SHORT TERM. SATELLITE SHOWING A COMPLICATED AND AMPLIFIED FLOW FROM THE PACIFIC INTO WESTERN NORTH AMERICA. RATHER STRONG/COLD AND POSITIVELY TILTED TROUGH IS APPROACHING FROM THE WEST THIS MORNING. COOL AND MOIST AIR MASS OVER THE AREA THIS MORNING IS EXPECTED TO GIVE WAY TO A WARMER AIR MASS THAT IS NOT TOO FAR AWAY. AT JET LEVEL...THE ECMWF AND CANADIAN WERE DOING A LITTLE BETTER THAN THE OTHERS WITH THE JET SEGMENT THAT IS GETTING CLOSER TO US. THAT OUTPUT WAS A LITTLE TOO FAR EAST. MODELS INITIALIZED WELL AT MID LEVELS. AT THE SURFACE...THE MODELS TENDED TO HAVE THE FRONT TO OUR SOUTH AND THE SURFACE TROUGH TO OUR WEST...TO FAR NORTH AND EAST. THE SREF WAS DOING A LITTLE BETTER THAN THE ECMWF AND NAM. THE RUC AND HRRR ARE CATCHING THE FOG WITH THE NAM NOT HAVING A CLUE ABOUT IT LIKE LAST NIGHT. THE SREF IS DOING BEST ON THE LOW LEVEL THERMAL FIELD AND IS A LITTLE BETTER THAN THE UKMET...ECMWF...AND GFS. TODAY/TONIGHT...FIRST CONCERN WHICH THE EVENING SHIFT ALREADY ADDRESSED HAS BEEN DENSE FOG. WILL CONTINUE TO MONITOR TRENDS. AT THIS TIME WILL KEEP THE CURRENT AREA OF THE ADVISORY BUT THERE ARE INDICATIONS THAT THE ADVISORY MAY NEED TO BE EXPANDED. BIG KEYS ON THE MAX TEMPERATURES IS HOW FAST THE STRATUS/FOG RETREATS/ENDS AND WHEN THE COLD FRONT LOOKS TO START MOVING IN THE NORTH. THE MODELS ARE SLOWER WITH THE FRONT. RUC/HRRR HAVE A GOOD HANDLE ON THE STRATUS/FOG AREA. IT LOOKS LIKE THE FAR NORTHEAST CORNER COULD NOT CLEAR UNTIL LATER THIS AFTERNOON. IF THAT IS THE CASE...THE TEMPERATURES I HAVE UP THERE WILL BE TOO WARM. SUFFICE TO SAY THERE COULD BE A HUGE GRADIENT IN TEMPERATURES TODAY. AND IF THAT IS NOT BAD ENOUGH...SOME MID AND HIGH LEVEL CLOUD COVER WILL START INCREASE IN THE WEST IN THE AFTERNOON. COMPARING THE RUC/HRRR TO THE BETTER 850 MB TEMPERATURE GUIDANCE WOULD SUPPORT 60S OVER AREAS THAT GET A LOT OF SUN...MAYBE EVEN 70 DEGREE READING. AS SURFACE RIDGE MOVES AWAY AND SURFACE LOW OVER EASTERN STRENGTHENS...GRADIENT IS EXPECTED TO TIGHTEN ALONG WITH MODERATE 3 HOUR PRESSURE FALLS. SO OVER THE SOUTHWEST PORTION OF THE AREA IT COULD GET BREEZY TO WINDY. THIS MAY CAUSE SOME FIRE WEATHER ISSUES. REFER TO THE FIRE WEATHER SECTION BELOW. BY LATE AFTERNOON...THE RIGHT REAR QUADRANT OF THE JET WILL BE AFFECTING THE SOUTHEAST HALF OF THE AREA. BY LATE EVENING THIS HAS MOVED EAST OF THE AREA. THIS JET LIFT IS OUT OF PHASE WITH THE DEEPER MOISTURE AND OTHER LIFT. AT THIS TIME ONLY EXPECT CLOUDS IN THE AFTERNOON FOR MOST OF THE AREA THIS AFTERNOON. AFTER THAT...ABOVE MENTIONED UPPER TROUGH...WITH RATHER COLD AIR ALOFT...IS EXPECTED TO START MOVE THROUGH DURING THE NIGHT. ON THE SOUTHERN END OF THIS TROUGH SPORADIC LIGHTNING STRIKES HAVE BEEN DETECTED. AM CONCERNED THIS SYSTEM IS COMING IN A LITTLE STRONGER THAN 00Z MODELS SHOWED DESPITE BEING AN OPEN WAVE AND MOVING THROUGH RATHER QUICKLY. NEWER DATA COME IN WITH A LITTLE BETTER MOISTURE PROFILE. AT THIS TIME THE NORTHWEST PORTION OF THE AREA CAME IN WITH THE BEST MOISTURE...INSTABILITY...AND LIFT SETUP. SO MADE THE HIGHEST POPS IN THERE DURING THE NIGHT. THE BEST PARAMETERS DO NOT REALLY START COMING INTO THE AREA UNTIL LATE IN THE EVENING. GRADIENT AND 3 HOUR PRESSURE RISES SUPPORT BREEZY TO MAYBE WINDY BEHIND THE FRONT. TUESDAY/TUESDAY NIGHT...TROUGH IS STILL TO THE WEST OF THE AREA AT 12Z WITH A RATHER STRONG PV ANOMALY INDICATED WITH IT. TROUGH/ANOMALY MOVE ACROSS DURING THE DAY. DESPITE WHAT APPEARS NOT THE BEST OF MOISTURE PROFILES...THE INSTABILITY AND STRENGTH OF THIS SYSTEM HAS ME CONCERNED ABOUT MEASURABLE SNOW/PRECIPITATION. SO RAISED POPS INTO THE 20 TO 30 PERCENT RANGE BUT COULD SEE THE POSSIBILITY OF NEEDING HIGHER POPS. ALSO IF THERE ENDS UP BEING MORE SNOW THAN I THINK...THERE COULD BE SOME BLOWING SNOW DUE TO THE STRONG AND GUSTY WINDS. IT IS POSSIBLE THAT THE WINDS COULD GET CLOSE TO WIND ADVISORY CRITERIA. MODELS ARE COMING IN COLDER AND MORE EXTENSIVE CLOUD COVER. SO REDUCED MAXES AND IF THE COLDER MODELS WORK OUT...I MAY BE TOO WARM. ANOTHER SHORTWAVE TROUGH...WEAK JET LIFT AND A REINFORCING SHORT OF COLD AIR COULD KEEP FLURRIES GOING THROUGH THE NIGHT. WEDNESDAY/WEDNESDAY NIGHT...SO HOW COLD DOES IT REMAIN BEHIND EXITING SYSTEM. MODELS IN GOOD AGREEMENT IN BRINGING IN MUCH COLDER ONCE THE TROUGH HAS MOVED TO THE EAST. ALSO AN INDICATION THAT THERE MAY BE MORE CLOUD COVER THAN INDICATED. SO LOWERED MAXES AGAIN. AGAIN WITH STRONG CYCLONIC FLOW WITH EMBEDDED SHORTWAVES...FLURRIES COULD BE A POSSIBILITY. THIS FLURRIE ACTIVITY ENDS DURING THE EVENING. .LONG TERM...(THURSDAY THROUGH SUNDAY) ISSUED AT 253 AM MST MON JAN 28 2013 MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD. THE LARGE UPPER LEVEL TROUGH ACROSS THE CENTRAL AND EASTERN UNITED STATES WILL CONTINUE MOVING SLOWLY TO THE EAST AND AN UPPER LEVEL RIDGE OF HIGH PRESSURE SHOULD BUILD IN FROM THE WEST TOWARDS THE END OF THE WEEK. A SURFACE HIGH PRESSURE WILL ALSO BECOME A PERSISTENT FEATURE ACROSS THE PLAINS. WITH A RIDGE OF HIGH PRESSURE BUILDING IN AND PERSISTENT SURFACE HIGH...PRECIPITATION CHANCES THROUGH MOST OF THE EXTENDED FORECAST APPEAR MINIMAL. THE ONLY CHANCE WOULD BE ON THURSDAY AS A WEAK SHORTWAVE ROTATES AROUND THE EDGE OF THE UPPER LEVEL TROUGH. MODELS HAVE BACKED OFF ON THE COVERAGE AND QPF AMOUNTS ACROSS THE TRI-STATE AREA SO HAVE MADE CHANGES IN THE FORECAST TO REFLECT THIS. AT THE PRESENT TIME...NO PRECIPITATION IS MENTIONED. THE TRICKY PORTION OF THE EXTENDED FORECAST CONCERNS THE HIGH TEMPERATURES. ON THURSDAY...MODELS INDICATE A TIGHT TEMPERATURE GRADIENT ACROSS THE REGION AS THE COLD FRONT THAT MOVES THROUGH ON MONDAY NIGHT LINGERS. THERE ARE SLIGHT DIFFERENCES IN THE GRADIENT LOCATION BETWEEN THE GFS...CANADIAN AND EUROPEAN MODELS. THE GFS IS COOLER THAN THE EUROPEAN SOLUTION BY 7 TO 8 DEGREES AS A RESULT. FOR FRIDAY THROUGH SUNDAY...A WARMING TREND IS EXPECTED AS ALL MODELS SHOW TEMPERATURES AT 850 MB WARMING. MODELS ARE IN BETTER AGREEMENT IN THIS TIME FRAME WITH GUIDANCE WITHIN A FEW DEGREES EACH DAY. THE GENERAL PATTERN THAT MODELS ARE PROJECTING IS VERY SIMILAR TO THE WARM SCENARIO THAT PLAYED OUT LAST WEEK. RAISED HIGH TEMPERATURES EACH DAY AS A RESULT OF LAST WEEKS WEATHER AND CONTINUED DROUGHT CONDITIONS. BOTH THE GFS AND EUROPEAN MODELS SHOW 850 MB TEMPERATURES CREEPING UP TO 10 DEGREES CELSIUS FOR SUNDAY...SO HAVE MADE SUNDAY THE WARMEST DAY IN THE EXTENDED WITH HIGHS APPROACHING 60 FOR MOST OF THE REGION. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 456 AM MST MON JAN 28 2013 HRRR CONTINUES TO HANDLE STRATUS AND FOG FIELD VERY WELL. FOR KGLD...IT LOOKS LIKE IFR/LIFR CONDITIONS WILL STAY TO THE EAST OF THE SITE THIS MORNING. KGLD MAY GET SOME BRIEF CONDITIONS BEFORE IMPROVING BY MID MORNING. OTHERWISE AT KGLD...AN UPPER LEVEL STORM SYSTEM AND ASSOCIATED COLD FRONT WILL MOVE INTO THE AREA TONIGHT. THIS WILL SPREAD MVFR AND POSSIBLE IFR CONDITIONS INTO THE AREA BEGINNING AROUND 04Z. MAY BE SOME SNOW AROUND HOWEVER CHOSE TO HANDLE WITH VCSH SINCE TOWARD THE END OF THE PERIOD. FOR KMCK...LIFR CONDITIONS WILL LAST THROUGH LATE MORNING BEFORE IMPROVEMENT. IT IS POSSIBLE IFR/MVFR CONDITIONS COULD LAST A FEW HOURS BEYOND THIS BUT LATER SHIFTS CAN ADDRESS WHEN IT BECOMES MORE CLEAR. STORM SYSTEM AND COLD FRONT MOVE INTO THE AREA LATER THIS EVENING. THIS WILL BRING IFR TO MVFR CEILINGS BACK TO THE AREA WITH LIGHT SNOW SHOWERS POSSIBLE AS WELL. && .FIRE WEATHER... ISSUED AT 401 AM MST MON JAN 28 2013 THE SOUTHWEST PORTION...ESPECIALLY FAR WESTERN CHEYENNE AND KIT CARSON COULD REACH CRITICAL FIRE WEATHER CONDITIONS. AT THIS TIME IT LOOKS LIKE THE RELATIVE HUMIDITIES STAY ABOVE 20 PERCENT WITH ADEQUATE WINDS NOT LASTING THREE HOURS. SO ISSUED NO HIGHLIGHT FOR THIS. BUT DAY SHIFT WILL NEED TO WATCH THIS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR KSZ002>004-014>016- 028-029. CO...NONE. NE...DENSE FOG ADVISORY UNTIL 11 AM MST /NOON CST/ THIS MORNING FOR NEZ079>081. && $$ UPDATE...BULLER SHORT TERM...BULLER LONG TERM...RRH AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
600 AM CST MON JAN 28 2013 ...UPDATE TO AVIATION... .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 313 AM CST MON JAN 28 2013 THE BIGGEST CHALLENGE TO THIS FORECAST IS HOW FAR SOUTHWEST WILL ANY DENSE FOG DEVELOP. THE SITES OF HLC, RSL, ICT, AND MCK HAVE ALL ALREADY BEEN DOWN TO 1/4SM IN DENSE FOG THIS MORNING. HYS HAS FLIRTED WITH 1SM AND GBD IS DOWN TO 3SM AT 08Z. THE RUC AND HRRR SHORT TERM MODELS ARE STRONG WITH FORECASTING LESS THAN A QUARTER OF A MILE FROM NEAR SCOTT CITY DOWN TO PRATT. HAVE DECIDED TO GO WITH AN NPW DENSE FOG ADVISORY FOR THIS AREA, UNTIL ABOUT 17Z. WINDS WILL CONTINUE TO BE LIGHT AND VARIABLE UNTIL ABOUT 17Z, THEN WILL GRADUALLY BECOME SOUTH OR SOUTHWEST AT 15 MPH GUSTING TO 20 MPH IN THE NPW AREA. THIS SHOULD DISSIPATE THE FOG RAPIDLY. AS WINDS BECOME STRONGER ACROSS SOUTHWEST KANSAS BY 18Z, GENERALLY IN THE 20G30MPH RANGE, WARM AIR JUST ABOVE THE SURFACE WILL MIX DOWN. AT 850MB, THE DDC TEMP AT 00Z WAS 3C WARMER THAN YESTERDAY, AND WAS AT +13C. A SWATH OF +14C AIR WAS OVER THE SOUTHERN TIER OF COUNTIES NEAR THE OKLAHOMA BORDER. THUS, I THINK HIGHS WILL REACH LEVELS SIMILAR TO YESTERDAY ALONG THE OKLAHOMA BORDER, WHERE A RECORD HIGH WAS SET AT P28 AT 74F. THE AREAS IN THE NORTH AND NORTHEAST, WHICH WILL HAVE A DELAYED PERIOD FOR HEATING DUE TO LOW CLOUDS AND FOG THIS MORNING, SHOULD ONLY SEE HIGHS IN THE UPPER 60S. AS FOR TONIGHT, THE WINDS WILL STAY IN THE 10 TO 15 MPH RANGE THROUGH ABOUT MIDNIGHT, THEN WILL DROP TO AROUND 10 MPH. A PRE-FRONTAL TROUGH WILL SLIDE THROUGH TO THE SOUTHEAST AND SWITCH WINDS TO THE NORTH AT 10 TO 15 MPH, FIRST IN THE SCOTT CITY AREA AND A LITTLE LATER IN THE GARDEN CITY AND DODGE CITY AREAS. COOL AIR WILL DROP INTO THE AREA NORTHWEST OF A LIBERAL TO DODGE CITY TO LA CROSSE LINE LATE TONIGHT. MINIMUMS THERE WILL AVERAGE IN THE UPPER 20S TO LOWER 30S. THE PRE-FRONTAL TROUGH WILL NOT REACH THE PRATT, MEDICINE LODGE AND COLDWATER AREAS PRIOR TO 12Z TUESDAY, SO MINIMUMS IN THOSE AREAS WILL STAY ELEVATED IN THE MID 40S. SOME HIGH CLOUDS WILL MOVE IN BEHIND THE WIND SHIFT, BUT SHOULD NOT BE THICK ENOUGH TO HAVE MUCH INFLUENCE ON THE MINIMUM TEMPERATURES. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 301 AM CST MON JAN 28 2013 MEDIUM RANGE MODELS INDICATE A STRONG UPPER LEVEL TROUGH OF LOW PRESSURE TRACKING EASTWARD ACROSS THE WESTERN HIGH PLAINS TUESDAY BRINGING THE POSSIBILITY FOR PRECIP GENERALLY FROM THE NORTHERN PLAINS SOUTHWARD INTO CENTRAL AND EAST TEXAS. AN ATTENDANT COLD FRONT IS PROJECTED TO PUSH THROUGH WESTERN KANSAS EARLY TUESDAY MORNING PROVIDING THE FOCUS FOR INCREASED LIFT NEAR THE SURFACE. HOWEVER, A STRONG SOUTHWESTERLY LOW LEVEL FLOW ACROSS ALL OF CENTRAL AND SOUTHWEST KANSAS MONDAY WILL KEEP A VAST POOL OF GULF MOISTURE BLOCKED OFF TO OUR EAST AND SOUTHEAST FROM EAST TEXAS NORTHEAST INTO MISSOURI. THIS WILL HINDER PRECIP CHANCES ACROSS WESTERN KANSAS TUESDAY. STILL, STRONG FAVORABLE DYNAMICS ALOFT COMBINED WITH JUST ENOUGH MID LEVEL MOISTURE MAY SUPPORT A FEW FLURRIES ACROSS PORTIONS OF WESTERN KANSAS TUESDAY AFTERNOON. DRIER CONDITIONS ARE LIKELY THROUGH THE END OF THE WEEK AS THE UPPER LEVEL TROUGH KICKS OFF TO THE EAST WHILE UPPER LEVEL RIDGING BEGINS TO TAKE HOLD IN THE INTERMOUNTAIN WEST LATE IN THE PERIOD. COOLER TEMPERATURES ARE LIKELY TUESDAY AS A STRONG COLD FRONT PUSHES THROUGH WESTERN KANSAS BY EARLY AFTERNOON. COLDER AIR WILL SURGE SOUTHWARD INTO WESTERN KANSAS BEHIND THE FRONT DROPPING H85 TEMPERATURES TO JUST BELOW 0C AS THE BOUNDARY MOVES THROUGH. ALTHOUGH THERE IS STILL UNCERTAINTY AS IT PERTAINS TO THE TIMING OF THE BOUNDARY PASSAGE, IT APPEARS HIGHS WILL BE REACHED BY MID TO LATE MORNING ACROSS WEST CENTRAL KANSAS WHILE HIGHS ARE REACHED IN SOUTH CENTRAL KANSAS BY EARLY TO MID AFTERNOON. AGAIN, TIMING OF THE FRONT WILL BE KEY, BUT LOOK FOR HIGHS GENERALLY UP INTO THE 40S(F) WITH THE LOWER TO MID 50S(F) STILL POSSIBLE IN SOUTH CENTRAL KANSAS JUST AHEAD OF THE FRONT. TEMPERATURES WILL REMAIN FAIRLY COLD WEDNESDAY AS ARCTIC AIR ASSOCIATED WITH A SURFACE HIGH IN THE NORTHERN PLAINS SPILLS SOUTH INTO THE CENTRAL PLAINS WITH H85 TEMPERATURES NEARING 10C BELOW ACROSS CENTRAL KANSAS NEAR THE I-70 CORRIDOR. THE GEM, GFS, AND ECMWF SHOW H85 TEMPERATURES CLOSER TO 0C IN EXTREME SOUTHWESTERN KANSAS. HIGHS MAY STRUGGLE TO REACH THE 30S(F) ACROSS CENTRAL KANSAS WEDNESDAY AFTERNOON WITH THE LOWER TO MID 40S(F) EXPECTED IN FAR SOUTHWEST KANSAS. A GRADUAL WARMING TREND IS THEN LIKELY THROUGH THE END OF THE WEEK AS UPPER LEVEL RIDGING BEGINS TO DEVELOP IN THE INTERMOUNTAIN WEST LATE IN THE PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 600 AM CST MON JAN 28 2013 AREAS OF DENSE FOG WILL CONTINUE TO DEVELOP AND SPREAD SOUTHWEST ACROSS CENTRAL AND PORTIONS OF SOUTHWEST KANSAS THROUGH SUNRISE THIS MORNING. IFR CONDITIONS ARE LIKELY AT KHYS AND KGCK...AND POSSIBLE AS FAR SOUTH AS KDDC. THE FOG WILL THEN BEGIN TO DISSIPATE GENERALLY AFTER 15Z GIVING WAY TO VFR CONDITIONS BY MID DAY. AS FOR WINDS, AN AREA OF LOW PRESSURE WILL STRENGTHEN ACROSS EASTERN COLORADO TODAY. AS A RESULT, LIGHT AND VARIABLE WINDS THIS MORNING WILL BECOME SOUTH TO SOUTHWESTERLY INCREASING UP TO 20 TO 30KT BY EARLY THIS AFTERNOON. THE WINDS WILL SUBSIDE THIS EVENING. && .PRELIMINARY POINT TEMPS/POPS... DDC 71 33 43 21 / 0 0 10 10 GCK 71 30 42 20 / 0 0 20 10 EHA 69 32 41 21 / 0 0 20 10 LBL 71 32 43 22 / 0 0 10 10 HYS 68 32 43 20 / 0 10 10 10 P28 75 44 55 24 / 0 0 10 10 && .DDC WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 11 AM CST THIS MORNING FOR KSZ030-031- 043>046-064>066-079-081. && $$ SHORT TERM...BURKE LONG TERM...JJOHNSON AVIATION...JJOHNSON
AREA FORECAST DISCUSSION
NWS WICHITA KS
539 AM CST MON JAN 28 2013 .AVIATION...12Z TAFS KRSL/KSLN/KHUT/KICT/KCNU VERY POOR AVIATION CONDITIONS WILL AFFECT ALL OF CENTRAL KANSAS THIS MORNING...WITH DENSE FOG BLANKETING THE REGION. THE FOG WILL BEGIN TO LIFT AS A WARM FRONT MOVES NORTHWARD INTO CENTRAL KANSAS AROUND NOON. SOUTH WINDS WILL INCREASE DURING THE AFTERNOON HOURS AND BECOME GUSTY AS SURFACE LOW PRESSURE DEEPENS OVER WESTERN KANSAS TODAY. MEANWHILE...A COLD FRONT WILL SINK SOUTHWARD INTO CENTRAL KANSAS LATE TONIGHT ALONG WITH SOME MVFR CIGS JUST BEHIND THE FRONTAL BOUNDARY. JAKUB && .PREV DISCUSSION... /ISSUED 328 AM CST MON JAN 28 2013/ DISCUSSION... FORECAST CONCERNS...DENSE FOG TRENDS THIS MORNING THEN CONVECTIVE CHANCES TONIGHT INTO TUESDAY. TODAY-TUESDAY COMBO OF RADIATIONAL AND ADVECTION FOG DEVELOPING IN VICINITY OF THE SURFACE FRONTAL BOUNDARY WHICH HAS BECOME QUASI-STATIONARY ACROSS THE AREA. THE LATEST RUC WOULD SUGGEST BETTER POTENTIAL FOR DENSE FOG WILL BE REALIZED JUST NORTH OF WICHITA AREA ACROSS CENTRAL KANSAS AS MOIST ADVECTION WITH FRONT DRIFTS SLOWLY NORTH DURING THE MORNING. A DENSE FOG ADVISORY WILL BE ISSUED FOR THESE AREAS. OTHERWISE NEAR RECORD WARMTH EXPECTED THIS AFTERNOON WITH WICHITA/CHANUTE AND SALINA POSSIBLY SETTING NEW RECORDS FOR THE DATE. SOUTH WINDS WILL ALSO PICK UP IN THE WARM SECTOR THIS AFTERNOON THOUGH SHOULD REMAIN BELOW WIND ADVISORY LEVELS. THE WARM/MOIST SOUTHERLY FLOW WILL RESULT IN MODEST INSTABILITY ACROSS SOUTHEAST KANSAS BY THIS EVENING WHERE DEEP LAYER SHEAR PROFILES WILL ALSO INCREASE. IF CONVECTION CAN DEVELOP A FEW STRONG TO MARGINALLY SEVERE STORMS WILL BE POSSIBLE. BROAD SCALE FORCING FOR ASCENT WILL RESIDE ACROSS THE WARM/MOIST SECTOR ACROSS SOUTHEAST KANSAS ON TUESDAY AHEAD OF THE UPPER TROF. WILL CONTINUE TO HIGHLIGHT SLIGHT RISK FOR SEVERE STORMS THOUGH LATEST FRONTAL TIMING WOULD SUGGEST BETTER CHANCES WILL SHIFT EAST OF THE AREA BY LATE AFTERNOON OR EARLY EVENING. SOME LIGHT POST-FRONTAL PRECIP IS POSSIBLE TUESDAY EVENING MAINLY ACROSS CENTRAL KANSAS...THOUGH GENERALLY TRACE SPRINKLES TO FLURRIES. WEDNESDAY BACK TO SEASONABLY COLD AIR FOR MID-WEEK AS THE MEAN UPPER TROF SHIFTS EAST FROM THE PLAINS ACROSS THE MIDWEST. LITTLE CHANGE TO THE FORECAST WITH DRY WEATHER. THURSDAY-SUNDAY ADDITIONAL SHORTWAVE TROFS WILL ROTATE THROUGH THE EASTERN CONUS LONGWAVE...HELPING TO REINFORCE THE CHILLY AIR ACROSS THE PLAINS ON THURSDAY...WITH GRADUAL TEMPERATURE MODERATION EXPECTED BY THE WEEKEND. DARMOFAL && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 73 48 57 25 / 10 10 10 10 HUTCHINSON 73 43 52 23 / 10 10 10 10 NEWTON 72 46 53 23 / 10 10 10 10 ELDORADO 71 50 58 26 / 10 10 10 10 WINFIELD-KWLD 74 52 63 27 / 10 10 10 10 RUSSELL 69 35 43 20 / 10 10 10 10 GREAT BEND 71 37 44 20 / 10 10 10 10 SALINA 70 40 47 22 / 10 10 10 10 MCPHERSON 72 42 50 22 / 10 10 10 10 COFFEYVILLE 73 59 67 32 / 10 30 60 10 CHANUTE 73 57 63 29 / 10 30 50 10 IOLA 73 57 63 28 / 10 30 50 10 PARSONS-KPPF 73 58 65 30 / 10 30 60 10 && .ICT WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR KSZ032-033- 047>053-067-068-082. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
401 AM MST MON JAN 28 2013 .SHORT TERM...(TODAY THROUGH TUESDAY NIGHT) ISSUED AT 401 AM MST MON JAN 28 2013 ONCE AGAIN THERE ARE NUMEROUS FORECAST PROBLEMS TO ADDRESS THROUGH THE SHORT TERM. SATELLITE SHOWING A COMPLICATED AND AMPLIFIED FLOW FROM THE PACIFIC INTO WESTERN NORTH AMERICA. RATHER STRONG/COLD AND POSITIVELY TILTED TROUGH IS APPROACHING FROM THE WEST THIS MORNING. COOL AND MOIST AIR MASS OVER THE AREA THIS MORNING IS EXPECTED TO GIVE WAY TO A WARMER AIR MASS THAT IS NOT TOO FAR AWAY. AT JET LEVEL...THE ECMWF AND CANADIAN WERE DOING A LITTLE BETTER THAN THE OTHERS WITH THE JET SEGMENT THAT IS GETTING CLOSER TO US. THAT OUTPUT WAS A LITTLE TOO FAR EAST. MODELS INITIALIZED WELL AT MID LEVELS. AT THE SURFACE...THE MODELS TENDED TO HAVE THE FRONT TO OUR SOUTH AND THE SURFACE TROUGH TO OUR WEST...TO FAR NORTH AND EAST. THE SREF WAS DOING A LITTLE BETTER THAN THE ECMWF AND NAM. THE RUC AND HRRR ARE CATCHING THE FOG WITH THE NAM NOT HAVING A CLUE ABOUT IT LIKE LAST NIGHT. THE SREF IS DOING BEST ON THE LOW LEVEL THERMAL FIELD AND IS A LITTLE BETTER THAN THE UKMET...ECMWF...AND GFS. TODAY/TONIGHT...FIRST CONCERN WHICH THE EVENING SHIFT ALREADY ADDRESSED HAS BEEN DENSE FOG. WILL CONTINUE TO MONITOR TRENDS. AT THIS TIME WILL KEEP THE CURRENT AREA OF THE ADVISORY BUT THERE ARE INDICATIONS THAT THE ADVISORY MAY NEED TO BE EXPANDED. BIG KEYS ON THE MAX TEMPERATURES IS HOW FAST THE STRATUS/FOG RETREATS/ENDS AND WHEN THE COLD FRONT LOOKS TO START MOVING IN THE NORTH. THE MODELS ARE SLOWER WITH THE FRONT. RUC/HRRR HAVE A GOOD HANDLE ON THE STRATUS/FOG AREA. IT LOOKS LIKE THE FAR NORTHEAST CORNER COULD NOT CLEAR UNTIL LATER THIS AFTERNOON. IF THAT IS THE CASE...THE TEMPERATURES I HAVE UP THERE WILL BE TOO WARM. SUFFICE TO SAY THERE COULD BE A HUGE GRADIENT IN TEMPERATURES TODAY. AND IF THAT IS NOT BAD ENOUGH...SOME MID AND HIGH LEVEL CLOUD COVER WILL START INCREASE IN THE WEST IN THE AFTERNOON. COMPARING THE RUC/HRRR TO THE BETTER 850 MB TEMPERATURE GUIDANCE WOULD SUPPORT 60S OVER AREAS THAT GET A LOT OF SUN...MAYBE EVEN 70 DEGREE READING. AS SURFACE RIDGE MOVES AWAY AND SURFACE LOW OVER EASTERN STRENGTHENS...GRADIENT IS EXPECTED TO TIGHTEN ALONG WITH MODERATE 3 HOUR PRESSURE FALLS. SO OVER THE SOUTHWEST PORTION OF THE AREA IT COULD GET BREEZY TO WINDY. THIS MAY CAUSE SOME FIRE WEATHER ISSUES. REFER TO THE FIRE WEATHER SECTION BELOW. BY LATE AFTERNOON...THE RIGHT REAR QUADRANT OF THE JET WILL BE AFFECTING THE SOUTHEAST HALF OF THE AREA. BY LATE EVENING THIS HAS MOVED EAST OF THE AREA. THIS JET LIFT IS OUT OF PHASE WITH THE DEEPER MOISTURE AND OTHER LIFT. AT THIS TIME ONLY EXPECT CLOUDS IN THE AFTERNOON FOR MOST OF THE AREA THIS AFTERNOON. AFTER THAT...ABOVE MENTIONED UPPER TROUGH...WITH RATHER COLD AIR ALOFT...IS EXPECTED TO START MOVE THROUGH DURING THE NIGHT. ON THE SOUTHERN END OF THIS TROUGH SPORADIC LIGHTNING STRIKES HAVE BEEN DETECTED. AM CONCERNED THIS SYSTEM IS COMING IN A LITTLE STRONGER THAN 00Z MODELS SHOWED DESPITE BEING AN OPEN WAVE AND MOVING THROUGH RATHER QUICKLY. NEWER DATA COME IN WITH A LITTLE BETTER MOISTURE PROFILE. AT THIS TIME THE NORTHWEST PORTION OF THE AREA CAME IN WITH THE BEST MOISTURE...INSTABILITY...AND LIFT SETUP. SO MADE THE HIGHEST POPS IN THERE DURING THE NIGHT. THE BEST PARAMETERS DO NOT REALLY START COMING INTO THE AREA UNTIL LATE IN THE EVENING. GRADIENT AND 3 HOUR PRESSURE RISES SUPPORT BREEZY TO MAYBE WINDY BEHIND THE FRONT. TUESDAY/TUESDAY NIGHT...TROUGH IS STILL TO THE WEST OF THE AREA AT 12Z WITH A RATHER STRONG PV ANOMALY INDICATED WITH IT. TROUGH/ANOMALY MOVE ACROSS DURING THE DAY. DESPITE WHAT APPEARS NOT THE BEST OF MOISTURE PROFILES...THE INSTABILITY AND STRENGTH OF THIS SYSTEM HAS ME CONCERNED ABOUT MEASURABLE SNOW/PRECIPITATION. SO RAISED POPS INTO THE 20 TO 30 PERCENT RANGE BUT COULD SEE THE POSSIBILITY OF NEEDING HIGHER POPS. ALSO IF THERE ENDS UP BEING MORE SNOW THAN I THINK...THERE COULD BE SOME BLOWING SNOW DUE TO THE STRONG AND GUSTY WINDS. IT IS POSSIBLE THAT THE WINDS COULD GET CLOSE TO WIND ADVISORY CRITERIA. MODELS ARE COMING IN COLDER AND MORE EXTENSIVE CLOUD COVER. SO REDUCED MAXES AND IF THE COLDER MODELS WORK OUT...I MAY BE TOO WARM. ANOTHER SHORTWAVE TROUGH...WEAK JET LIFT AND A REINFORCING SHORT OF COLD AIR COULD KEEP FLURRIES GOING THROUGH THE NIGHT. WEDNESDAY/WEDNESDAY NIGHT...SO HOW COLD DOES IT REMAIN BEHIND EXITING SYSTEM. MODELS IN GOOD AGREEMENT IN BRINGING IN MUCH COLDER ONCE THE TROUGH HAS MOVED TO THE EAST. ALSO AN INDICATION THAT THERE MAY BE MORE CLOUD COVER THAN INDICATED. SO LOWERED MAXES AGAIN. AGAIN WITH STRONG CYCLONIC FLOW WITH EMBEDDED SHORTWAVES...FLURRIES COULD BE A POSSIBILITY. THIS FLURRIE ACTIVITY ENDS DURING THE EVENING. .LONG TERM...(THURSDAY THROUGH SUNDAY) ISSUED AT 253 AM MST MON JAN 28 2013 MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD. THE LARGE UPPER LEVEL TROUGH ACROSS THE CENTRAL AND EASTERN UNITED STATES WILL CONTINUE MOVING SLOWLY TO THE EAST AND AN UPPER LEVEL RIDGE OF HIGH PRESSURE SHOULD BUILD IN FROM THE WEST TOWARDS THE END OF THE WEEK. A SURFACE HIGH PRESSURE WILL ALSO BECOME A PERSISTENT FEATURE ACROSS THE PLAINS. WITH A RIDGE OF HIGH PRESSURE BUILDING IN AND PERSISTENT SURFACE HIGH...PRECIPITATION CHANCES THROUGH MOST OF THE EXTENDED FORECAST APPEAR MINIMAL. THE ONLY CHANCE WOULD BE ON THURSDAY AS A WEAK SHORTWAVE ROTATES AROUND THE EDGE OF THE UPPER LEVEL TROUGH. MODELS HAVE BACKED OFF ON THE COVERAGE AND QPF AMOUNTS ACROSS THE TRI-STATE AREA SO HAVE MADE CHANGES IN THE FORECAST TO REFLECT THIS. AT THE PRESENT TIME...NO PRECIPITATION IS MENTIONED. THE TRICKY PORTION OF THE EXTENDED FORECAST CONCERNS THE HIGH TEMPERATURES. ON THURSDAY...MODELS INDICATE A TIGHT TEMPERATURE GRADIENT ACROSS THE REGION AS THE COLD FRONT THAT MOVES THROUGH ON MONDAY NIGHT LINGERS. THERE ARE SLIGHT DIFFERENCES IN THE GRADIENT LOCATION BETWEEN THE GFS...CANADIAN AND EUROPEAN MODELS. THE GFS IS COOLER THAN THE EUROPEAN SOLUTION BY 7 TO 8 DEGREES AS A RESULT. FOR FRIDAY THROUGH SUNDAY...A WARMING TREND IS EXPECTED AS ALL MODELS SHOW TEMPERATURES AT 850 MB WARMING. MODELS ARE IN BETTER AGREEMENT IN THIS TIME FRAME WITH GUIDANCE WITHIN A FEW DEGREES EACH DAY. THE GENERAL PATTERN THAT MODELS ARE PROJECTING IS VERY SIMILAR TO THE WARM SCENARIO THAT PLAYED OUT LAST WEEK. RAISED HIGH TEMPERATURES EACH DAY AS A RESULT OF LAST WEEKS WEATHER AND CONTINUED DROUGHT CONDITIONS. BOTH THE GFS AND EUROPEAN MODELS SHOW 850 MB TEMPERATURES CREEPING UP TO 10 DEGREES CELSIUS FOR SUNDAY...SO HAVE MADE SUNDAY THE WARMEST DAY IN THE EXTENDED WITH HIGHS APPROACHING 60 FOR MOST OF THE REGION. THANKS TO ALL FOR THE COLLABORATION. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1000 PM MST SUN JAN 27 2013 FOR KGLD...SOUTH TO SOUTHWEST WINDS AROUND 10KTS EXPECTED THROUGH LATE MORNING MONDAY BEFORE INCREASING INTO THE 17G27KT RANGE BY 17Z AHEAD OF AN APPROACHING COLD FRONT. SHOULD SEE A DECREASE IN WIND AROUND 00Z BEFORE SHIFTING TO THE NORTHWEST AROUND 04Z WITH GUSTS AROUND 20KTS POSSIBLE. FIRST IMPACT TO AN OTHERWISE VFR FORECAST IS STRATUS/FOG THAT IS FORECAST TO BACK IN TOWARD THE TERMINAL IN THE 12Z-16Z TIMEFRAME. GIVEN THE MODELS GENERALLY DONT GO FAR ENOUGH WEST WITH THE MOISTURE HAVE A TEMPO GROUP FOR VIS AROUND 4SM. NEXT CHANCE FOR MVFR/IFR CONDITIONS WILL BE IMMEDIATELY BEHIND THE FRONT MONDAY NIGHT WHERE CIGS AROUND 1500FT EXPECTED. FOR KMCK...CURRENTLY SEEING VFR CONDITIONS WITH VIS AROUND 4SM IN MIST. CONFIDENCE IS HIGHER THAT CONDITIONS WILL DETERIORATE TO IFR/VLIFR BY 10Z AND CONTINUE THROUGH 16Z OR SO IN FG WITH VIS AROUND 1/4 MILE. CONDITIONS SHOULD RETURN TO VFR SHORTLY AFTER 16Z ONLY TO FALL BACK INTO THE MVFR/IFR RANGE AFTER 02Z AS A COLD FRONT MOVES THROUGH. && .FIRE WEATHER... ISSUED AT 401 AM MST MON JAN 28 2013 THE SOUTHWEST PORTION...ESPECIALLY FAR WESTERN CHEYENNE AND KIT CARSON COULD REACH CRITICAL FIRE WEATHER CONDITIONS. AT THIS TIME IT LOOKS LIKE THE RELATIVE HUMIDITIES STAY ABOVE 20 PERCENT WITH ADEQUATE WINDS NOT LASTING THREE HOURS. SO ISSUED NO HIGHLIGHT FOR THIS. BUT DAY SHIFT WILL NEED TO WATCH THIS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL NOON CST MONDAY FOR KSZ002>004-014>016- 028-029. CO...NONE. NE...DENSE FOG ADVISORY UNTIL NOON CST MONDAY FOR NEZ080-081. && $$ SHORT TERM...BULLER LONG TERM...RRH AVIATION...DDT
AREA FORECAST DISCUSSION
NWS GOODLAND KS
253 AM MST MON JAN 28 2013 .UPDATE... ISSUED AT 1025 PM MST SUN JAN 27 2013 HAVE ISSUED A DENSE FOG ADVISORY THAT IS IN EFFECT NOW THROUGH 11 AM MST MONDAY MORNING. ASOS/AWOS SITES REPORTING VISIBILITIES FROM 1/4SM AT KHLC TO 2.5SM AT KCBK. LATEST 03Z RUC/HRRR AND LOCAL WRF MODEL ALL AGREE THAT THE DENSE FOG ALONG OUR FAR EASTERN FORECAST AREA WILL PUSH WESTWARD THROUGH THE REST OF THE NIGHT AND CONTINUE THROUGH THE MORNING MONDAY. UPDATE ISSUED AT 745 PM MST SUN JAN 27 2013 KNRN (NORTON) REPORTING 1/4SM FG AT PRESENT TIME WHILE KHLC (HILL CITY) AT 3SM. FORECAST CONCERNS FOR THE OVERNIGHT HOURS INTO EARLY MONDAY MORNING REVOLVE AROUND EXTENT OF FOG AND THREAT FOR DENSE FOG. HAVE BEEFED UP COVERAGE OF FOG WITH WIDESPREAD FOG EXPECTED FROM ROUGHLY TRENTON OR MCCOOK SOUTH THROUGH OAKLEY AND GOVE TONIGHT INTO EARLY MONDAY MORNING WHERE WINDS REMAIN LIGHT AND DECOUPLING OCCURS. GIVEN THE OBSERVATIONS AT KNRN AT 1/4SM ALREADY HARD TO DISCOUNT THE NEED FOR A DENSE FOG ADVISORY. WILL WATCH FOR TRENDS AND EVALUATE 03Z RUC/LATEST HRRR MODEL RUNS BEFORE MAKING A DECISION. OTHERWISE SHOULD BE GENERALLY CLEAR OUTSIDE OF THE FOG ALTHOUGH SOME MID AND HIGH CLOUDS START TO MOVE INTO FAR EASTERN COLORADO TOWARD SUNRISE AND SLOWLY INCREASE IN COVERAGE DURING THE DAY. && .SHORT TERM...(THIS EVENING THROUGH MONDAY EVENING) ISSUED AT 1258 PM MST SUN JAN 27 2013 LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW POSITIVELY TILTED TROUGH EXTENDING FROM BRITISH COLUMBIA TO CENTRAL CALIFORNIA...WITH SW FLOW ACROSS THE INTER-MOUNTAIN WEST AND CENTRAL PLAINS. SUBSIDENCE IS IN PLACE OVER CENTRAL KS AND CENTRAL CO WITH SEVERAL WEAK SHORTWAVES OVER THE NORTHERN PLAINS. A SURFACE TROUGH IS IN PLACE OVER THE CWA WITH A STALLED WARM FRONT JUST NORTHEAST OF THE CWA IN CENTRAL NEBRASKA. AREAS OF FOG/STRATUS MAY REDEVELOP OVERNIGHT TONIGHT PRIMARILY ALONG THE STATIONARY FRONT IN NEBRASKA...AND THEN SPREAD SW INTO OUR CWA. MOST GUIDANCE IS KEEPING FOG TO THE NORTH AND EAST OF THE CWA...HOWEVER LATEST 24HR RUC IS SHOWING FOG/STRATUS OVERSPREADING THE NE HALF OF CWA. WITH HIGHER TD VALUES POSSIBLY LINGERING ACROSS THE NE HALF OF THE CWA AND LOW LEVELS DECOUPLING...THE RUC SOLUTION SEEMS REASONABLE. ACROSS THE WEST AND SOUTH THE BL SHOULD BEGIN TO DRY OUT OVERNIGHT WITH S/SW FLOW...SO FOG POTENTIAL SHOULD BE MINIMAL CLOSER TO THE KS/CO STATE LINE. AS UPPER LEVEL TROUGH IN THE WEST SHIFTS WEST AND ASSOCIATED COLD FRONT PUSHES SOUTHEAST MONDAY...LEE TROUGH WILL STRENGTHEN WITH STRONG WAA AND BREEZY CONDITIONS ACROSS THE CWA. HIGH TEMP FORECAST IS COMPLICATED BY THE POSSIBILITY OF LINGERING STRATUS...AND INCREASING CLOUDS AS COLD FRONT AND UPPER TROUGH APPROACH CWA LATER IN THE AFTERNOON. WE COULD ALSO START TO SEE RAIN CHANCES INCREASE LATE IN THE AFTERNOON ACROSS THE NORTH/NORTHWEST. FOR NOW I KEPT HIGH TEMPS IN LINE WITH PREVIOUS FORECAST...WITH NEAR RECORD HIGHS IN THE MID TO UPPER 60S ACROSS NW KANSAS...AND SLIGHTLY COOLER TEMPS ACROSS THE NORTH. .LONG TERM...(THURSDAY THROUGH SUNDAY) ISSUED AT 253 AM MST MON JAN 28 2013 MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD. THE LARGE UPPER LEVEL TROUGH ACROSS THE CENTRAL AND EASTERN UNITED STATES WILL CONTINUE MOVING SLOWLY TO THE EAST AND AN UPPER LEVEL RIDGE OF HIGH PRESSURE SHOULD BUILD IN FROM THE WEST TOWARDS THE END OF THE WEEK. A SURFACE HIGH PRESSURE WILL ALSO BECOME A PERSISTENT FEATURE ACROSS THE PLAINS. WITH A RIDGE OF HIGH PRESSURE BUILDING IN AND PERSISTENT SURFACE HIGH...PRECIPITATION CHANCES THROUGH MOST OF THE EXTENDED FORECAST APPEAR MINIMAL. THE ONLY CHANCE WOULD BE ON THURSDAY AS A WEAK SHORTWAVE ROTATES AROUND THE EDGE OF THE UPPER LEVEL TROUGH. MODELS HAVE BACKED OFF ON THE COVERAGE AND QPF AMOUNTS ACROSS THE TRI-STATE AREA SO HAVE MADE CHANGES IN THE FORECAST TO REFLECT THIS. AT THE PRESENT TIME...NO PRECIPITATION IS MENTIONED. THE TRICKY PORTION OF THE EXTENDED FORECAST CONCERNS THE HIGH TEMPERATURES. ON THURSDAY...MODELS INDICATE A TIGHT TEMPERATURE GRADIENT ACROSS THE REGION AS THE COLD FRONT THAT MOVES THROUGH ON MONDAY NIGHT LINGERS. THERE ARE SLIGHT DIFFERENCES IN THE GRADIENT LOCATION BETWEEN THE GFS...CANADIAN AND EUROPEAN MODELS. THE GFS IS COOLER THAN THE EUROPEAN SOLUTION BY 7 TO 8 DEGREES AS A RESULT. FOR FRIDAY THROUGH SUNDAY...A WARMING TREND IS EXPECTED AS ALL MODELS SHOW TEMPERATURES AT 850 MB WARMING. MODELS ARE IN BETTER AGREEMENT IN THIS TIME FRAME WITH GUIDANCE WITHIN A FEW DEGREES EACH DAY. THE GENERAL PATTERN THAT MODELS ARE PROJECTING IS VERY SIMILAR TO THE WARM SCENARIO THAT PLAYED OUT LAST WEEK. RAISED HIGH TEMPERATURES EACH DAY AS A RESULT OF LAST WEEKS WEATHER AND CONTINUED DROUGHT CONDITIONS. BOTH THE GFS AND EUROPEAN MODELS SHOW 850 MB TEMPERATURES CREEPING UP TO 10 DEGREES CELSIUS FOR SUNDAY...SO HAVE MADE SUNDAY THE WARMEST DAY IN THE EXTENDED WITH HIGHS APPROACHING 60 FOR MOST OF THE REGION. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1000 PM MST SUN JAN 27 2013 FOR KGLD...SOUTH TO SOUTHWEST WINDS AROUND 10KTS EXPECTED THROUGH LATE MORNING MONDAY BEFORE INCREASING INTO THE 17G27KT RANGE BY 17Z AHEAD OF AN APPROACHING COLD FRONT. SHOULD SEE A DECREASE IN WIND AROUND 00Z BEFORE SHIFTING TO THE NORTHWEST AROUND 04Z WITH GUSTS AROUND 20KTS POSSIBLE. FIRST IMPACT TO AN OTHERWISE VFR FORECAST IS STRATUS/FOG THAT IS FORECAST TO BACK IN TOWARD THE TERMINAL IN THE 12Z-16Z TIMEFRAME. GIVEN THE MODELS GENERALLY DONT GO FAR ENOUGH WEST WITH THE MOISTURE HAVE A TEMPO GROUP FOR VIS AROUND 4SM. NEXT CHANCE FOR MVFR/IFR CONDITIONS WILL BE IMMEDIATELY BEHIND THE FRONT MONDAY NIGHT WHERE CIGS AROUND 1500FT EXPECTED. FOR KMCK...CURRENTLY SEEING VFR CONDITIONS WITH VIS AROUND 4SM IN MIST. CONFIDENCE IS HIGHER THAT CONDITIONS WILL DETERIORATE TO IFR/VLIFR BY 10Z AND CONTINUE THROUGH 16Z OR SO IN FG WITH VIS AROUND 1/4 MILE. CONDITIONS SHOULD RETURN TO VFR SHORTLY AFTER 16Z ONLY TO FALL BACK INTO THE MVFR/IFR RANGE AFTER 02Z AS A COLD FRONT MOVES THROUGH. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR KSZ002>004-014>016- 028-029. CO...NONE. NE...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR NEZ080-081. && $$ UPDATE...99 SHORT TERM...DR LONG TERM...RRH AVIATION...99
AREA FORECAST DISCUSSION
NWS WICHITA KS
328 AM CST MON JAN 28 2013 .DISCUSSION... FORECAST CONCERNS...DENSE FOG TRENDS THIS MORNING THEN CONVECTIVE CHANCES TONIGHT INTO TUESDAY. TODAY-TUESDAY COMBO OF RADIATIONAL AND ADVECTION FOG DEVELOPING IN VICINITY OF THE SURFACE FRONTAL BOUNDARY WHICH HAS BECOME QUASI-STATIONARY ACROSS THE AREA. THE LATEST RUC WOULD SUGGEST BETTER POTENTIAL FOR DENSE FOG WILL BE REALIZED JUST NORTH OF WICHITA AREA ACROSS CENTRAL KANSAS AS MOIST ADVECTION WITH FRONT DRIFTS SLOWLY NORTH DURING THE MORNING. A DENSE FOG ADVISORY WILL BE ISSUED FOR THESE AREAS. OTHERWISE NEAR RECORD WARMTH EXPECTED THIS AFTERNOON WITH WICHITA/CHANUTE AND SALINA POSSIBLY SETTING NEW RECORDS FOR THE DATE. SOUTH WINDS WILL ALSO PICK UP IN THE WARM SECTOR THIS AFTERNOON THOUGH SHOULD REMAIN BELOW WIND ADVISORY LEVELS. THE WARM/MOIST SOUTHERLY FLOW WILL RESULT IN MODEST INSTABILITY ACROSS SOUTHEAST KANSAS BY THIS EVENING WHERE DEEP LAYER SHEAR PROFILES WILL ALSO INCREASE. IF CONVECTION CAN DEVELOP A FEW STRONG TO MARGINALLY SEVERE STORMS WILL BE POSSIBLE. BROAD SCALE FORCING FOR ASCENT WILL RESIDE ACROSS THE WARM/MOIST SECTOR ACROSS SOUTHEAST KANSAS ON TUESDAY AHEAD OF THE UPPER TROF. WILL CONTINUE TO HIGHLIGHT SLIGHT RISK FOR SEVERE STORMS THOUGH LATEST FRONTAL TIMING WOULD SUGGEST BETTER CHANCES WILL SHIFT EAST OF THE AREA BY LATE AFTERNOON OR EARLY EVENING. SOME LIGHT POST-FRONTAL PRECIP IS POSSIBLE TUESDAY EVENING MAINLY ACROSS CENTRAL KANSAS...THOUGH GENERALLY TRACE SPRINKLES TO FLURRIES. WEDNESDAY BACK TO SEASONABLY COLD AIR FOR MID-WEEK AS THE MEAN UPPER TROF SHIFTS EAST FROM THE PLAINS ACROSS THE MIDWEST. LITTLE CHANGE TO THE FORECAST WITH DRY WEATHER. THURSDAY-SUNDAY ADDITIONAL SHORTWAVE TROFS WILL ROTATE THROUGH THE EASTERN CONUS LONGWAVE...HELPING TO REINFORCE THE CHILLY AIR ACROSS THE PLAINS ON THURSDAY...WITH GRADUAL TEMPERATURE MODERATION EXPECTED BY THE WEEKEND. DARMOFAL && .AVIATION...06Z TAFS KRSL/KSLN/KHUT/KICT/KCNU CIGS IN THE 1,000-1,500FT RANGE HAVE COVERED ALL OF E & SE KS THIS EVE. AT 04Z...THESE CIGS ARE SPREADING SLOWLY W/SW TOWARD CNTRL & SC KS. AS A WELL-DEFINED NEARLY STATIONARY FRONT THAT IS MEANDERING ALONG & JUST NW OF THE TURNPIKE GRADUALLY STRENGTHENS...MUCH WARMER...MOISTURE LADEN AIR WILL SPREAD ACROSS CNTRL KS. KSLN & KRSL WILL EXPERIENCE VLIFR CIGS & VSBYS ~10-15Z WITH REMAINING TERMINALS IN IFR STATUS THESE PERIODS. WITH A SFC LOW DEVELOPING OVER SE WY/NE CO STRENGTHENING CONSIDERABLY AS IT MOVES S ACROSS ERN CO...S/SW FLOW WILL INCREASE & WOULD QUICKLY SCOUR STRATUS & FOG FROM THESE AREAS ~15Z WITH KCNU CLEARING ~21Z. ES && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 73 48 57 24 / 10 10 10 10 HUTCHINSON 73 43 52 23 / 10 10 10 10 NEWTON 72 46 54 23 / 10 10 10 10 ELDORADO 71 50 58 26 / 10 10 10 10 WINFIELD-KWLD 74 52 63 27 / 10 10 10 10 RUSSELL 69 35 43 20 / 10 10 10 10 GREAT BEND 71 37 44 20 / 10 10 10 10 SALINA 70 40 47 22 / 10 10 10 10 MCPHERSON 72 42 50 22 / 10 10 10 10 COFFEYVILLE 73 59 66 32 / 10 30 60 10 CHANUTE 73 57 63 28 / 10 30 50 10 IOLA 73 57 63 28 / 10 30 50 10 PARSONS-KPPF 73 58 65 30 / 10 30 60 10 && .ICT WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR KSZ032-033- 047>053-067-068-082. && $$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
322 AM CST MON JAN 28 2013 ...UPDATED FOR THE SHORT TERM FORECAST... .SYNOPSIS... ISSUED AT 305 PM CST SUN JAN 27 2013 A BROAD UPPER LEVEL RIDGE REMAINED IN PLACE ACROSS MUCH OF THE UNITED STATES TODAY, AS A SHARP AMPLIFYING POSITIVELY TILTED TROUGH HELPED TO AMPLIFY THE RIDGE BY DIVING SOUTHEAST THROUGH THE PACIFIC NORTHWEST. A 850-700 MB TROUGH WAS PRESENT ACROSS THE CENTRAL AND HIGH PLAINS REGION OF KANSAS AND NEBRASKA. VERY WARM AIR ON THE ORDER OF +12 TO +15 DEGREES C WAS BEING PULLED NORTH INTO SOUTH CENTRAL KANSAS IN THE BOUNDARY LAYER. A 50 KNOT LOW LEVEL JET ALSO CONTRIBUTED TO CLEARING SKIES THROUGH SUBSIDENCE OVER MOST OF SOUTHWEST KANSAS THROUGH THE MORNING HOURS. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 313 AM CST MON JAN 28 2013 THE BIGGEST CHALLENGE TO THIS FORECAST IS HOW FAR SOUTHWEST WILL ANY DENSE FOG DEVELOP. THE SITES OF HLC, RSL, ICT, AND MCK HAVE ALL ALREADY BEEN DOWN TO 1/4SM IN DENSE FOG THIS MORNING. HYS HAS FLIRTED WITH 1SM AND GBD IS DOWN TO 3SM AT 08Z. THE RUC AND HRRR SHORT TERM MODELS ARE STRONG WITH FORECASTING LESS THAN A QUARTER OF A MILE FROM NEAR SCOTT CITY DOWN TO PRATT. HAVE DECIDED TO GO WITH AN NPW DENSE FOG ADVISORY FOR THIS AREA, UNTIL ABOUT 17Z. WINDS WILL CONTINUE TO BE LIGHT AND VARIABLE UNTIL ABOUT 17Z, THEN WILL GRADUALLY BECOME SOUTH OR SOUTHWEST AT 15 MPH GUSTING TO 20 MPH IN THE NPW AREA. THIS SHOULD DISSIPATE THE FOG RAPIDLY. AS WINDS IN OUR SOUTHWEST FORECAST AREA, NEAR ELKHART, GCK AND DDC, BECOME EVEN STRONGER BY 18Z, IN THE 20G30MPH RANGE, STRONG WARM AIR WILL MIX DOWN. AS OPPOSED TO YESTERDAY WHEN A LOW LEVEL JET WAS OVER US, TODAY THE WARM AIR IS ALREADY IN PLACE. AT 850MB, THE DDC TEMP AT 00Z WAS 3C WARMER THAN YESTERDAY, AND WAS AT +13C. A SWATH OF +14C AIR WAS OVER THE SOUTHERN TIER OF COUNTIES NEAR THE OKLAHOMA BORDER. THUS, I THINK HIGHS WILL REACH LEVELS SIMILAR TO YESTERDAY ALONG THE OKLAHOMA BORDER, WHERE A RECORD HIGH WAS SET AT P28 AT 74F. THE AREAS IN THE NORTH AND NORTHEAST, WHICH WILL HAVE A DELAYED PERIOD FOR HEATING DUE TO LOW CLOUDS AND FOG THIS MORNING, SHOULD ONLY SEE HIGHS IN THE UPPER 60S. AS FOR TONIGHT, THE WINDS WILL STAY IN THE 10 TO 15 MPH RANGE THROUGH ABOUT MIDNIGHT, THEN WILL DROP TO AROUND 10 MPH. A PRE-FRONTAL TROUGH WILL SLIDE THROUGH TO THE SOUTHEAST AND SWITCH WINDS TO THE NORTH AT 10 TO 15 MPH, FIRST IN THE SCOTT CITY AREA AND A LITTLE LATER IN THE GARDEN CITY AND DODGE CITY AREAS. COOL AIR WILL DROP INTO THE AREA NORTHWEST OF A LIBERAL TO DODGE CITY TO LA CROSSE LINE LATE TONIGHT. MINIMUMS THERE WILL AVERAGE IN THE UPPER 20S TO LOWER 30S. THE PRE-FRONTAL TROUGH WILL NOT REACH THE PRATT, MEDICINE LODGE AND COLDWATER AREAS PRIOR TO 12Z TUESDAY, SO MINIMUMS IN THOSE AREAS WILL STAY ELEVATED IN THE MID 40S. SOME HIGH CLOUDS WILL MOVE IN BEHIND THE WIND SHIFT, BUT SHOULD NOT BE THICK ENOUGH TO HAVE MUCH INFLUENCE ON THE MINIMUM TEMPERATURES. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 301 AM CST MON JAN 28 2013 MEDIUM RANGE MODELS INDICATE A STRONG UPPER LEVEL TROUGH OF LOW PRESSURE TRACKING EASTWARD ACROSS THE WESTERN HIGH PLAINS TUESDAY BRINGING THE POSSIBILITY FOR PRECIP GENERALLY FROM THE NORTHERN PLAINS SOUTHWARD INTO CENTRAL AND EAST TEXAS. AN ATTENDANT COLD FRONT IS PROJECTED TO PUSH THROUGH WESTERN KANSAS EARLY TUESDAY MORNING PROVIDING THE FOCUS FOR INCREASED LIFT NEAR THE SURFACE. HOWEVER, A STRONG SOUTHWESTERLY LOW LEVEL FLOW ACROSS ALL OF CENTRAL AND SOUTHWEST KANSAS MONDAY WILL KEEP A VAST POOL OF GULF MOISTURE BLOCKED OFF TO OUR EAST AND SOUTHEAST FROM EAST TEXAS NORTHEAST INTO MISSOURI. THIS WILL HINDER PRECIP CHANCES ACROSS WESTERN KANSAS TUESDAY. STILL, STRONG FAVORABLE DYNAMICS ALOFT COMBINED WITH JUST ENOUGH MID LEVEL MOISTURE MAY SUPPORT A FEW FLURRIES ACROSS PORTIONS OF WESTERN KANSAS TUESDAY AFTERNOON. DRIER CONDITIONS ARE LIKELY THROUGH THE END OF THE WEEK AS THE UPPER LEVEL TROUGH KICKS OFF TO THE EAST WHILE UPPER LEVEL RIDGING BEGINS TO TAKE HOLD IN THE INTERMOUNTAIN WEST LATE IN THE PERIOD. COOLER TEMPERATURES ARE LIKELY TUESDAY AS A STRONG COLD FRONT PUSHES THROUGH WESTERN KANSAS BY EARLY AFTERNOON. COLDER AIR WILL SURGE SOUTHWARD INTO WESTERN KANSAS BEHIND THE FRONT DROPPING H85 TEMPERATURES TO JUST BELOW 0C AS THE BOUNDARY MOVES THROUGH. ALTHOUGH THERE IS STILL UNCERTAINTY AS IT PERTAINS TO THE TIMING OF THE BOUNDARY PASSAGE, IT APPEARS HIGHS WILL BE REACHED BY MID TO LATE MORNING ACROSS WEST CENTRAL KANSAS WHILE HIGHS ARE REACHED IN SOUTH CENTRAL KANSAS BY EARLY TO MID AFTERNOON. AGAIN, TIMING OF THE FRONT WILL BE KEY, BUT LOOK FOR HIGHS GENERALLY UP INTO THE 40S(F) WITH THE LOWER TO MID 50S(F) STILL POSSIBLE IN SOUTH CENTRAL KANSAS JUST AHEAD OF THE FRONT. TEMPERATURES WILL REMAIN FAIRLY COLD WEDNESDAY AS ARCTIC AIR ASSOCIATED WITH A SURFACE HIGH IN THE NORTHERN PLAINS SPILLS SOUTH INTO THE CENTRAL PLAINS WITH H85 TEMPERATURES NEARING 10C BELOW ACROSS CENTRAL KANSAS NEAR THE I-70 CORRIDOR. THE GEM, GFS, AND ECMWF SHOW H85 TEMPERATURES CLOSER TO 0C IN EXTREME SOUTHWESTERN KANSAS. HIGHS MAY STRUGGLE TO REACH THE 30S(F) ACROSS CENTRAL KANSAS WEDNESDAY AFTERNOON WITH THE LOWER TO MID 40S(F) EXPECTED IN FAR SOUTHWEST KANSAS. A GRADUAL WARMING TREND IS THEN LIKELY THROUGH THE END OF THE WEEK AS UPPER LEVEL RIDGING BEGINS TO DEVELOP IN THE INTERMOUNTAIN WEST LATE IN THE PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1123 PM CST SUN JAN 27 2013 SURFACE HIGH PRESSURE WAS OVER WESTERN KANSAS EARLY THIS MORNING. AS LIGHT AND VARIABLE WINDS AND CLEAR SKY CONDITIONS PREVAIL, SOME DENSE FOG AND POSSIBLY SOME LOW STRATUS, PRODUCING IFR CONDITIONS, ARE LIKELY IN THE KHYS TAF SITE, BETWEEN 08Z AND 13Z THIS MORNING. AT KGCK AND KDDC, FOG IS NOT LIKELY TO BE AS DENSE, ONLY IN THE 3SM TO 4SM BR MVFR CATEGORY. AFTER SUNRISE, THE FOG WILL BURN OFF AND A LIGHT SOUTHWESTERLY FLOW WILL DEVELOP. AFTER 18Z, A LEE SIDE TROUGH WILL PRODUCE SOUTH WINDS IN THE 18G26KT RANGE AT ALL TAF SITES. && .PRELIMINARY POINT TEMPS/POPS... DDC 71 33 43 21 / 0 0 10 10 GCK 71 30 42 20 / 0 0 20 10 EHA 69 32 41 21 / 0 0 20 10 LBL 71 32 43 22 / 0 0 10 10 HYS 68 32 43 20 / 0 10 10 10 P28 75 44 55 24 / 0 0 10 10 && .DDC WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 11 AM CST THIS MORNING FOR KSZ030-031- 043>046-064>066-079-081. && $$ SYNOPSIS...RUSSELL SHORT TERM...BURKE LONG TERM...JJOHNSON AVIATION...BURKE
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1026 PM MST SUN JAN 27 2013 .UPDATE... ISSUED AT 1025 PM MST SUN JAN 27 2013 HAVE ISSUED A DENSE FOG ADVISORY THAT IS IN EFFECT NOW THROUGH 11 AM MST MONDAY MORNING. ASOS/AWOS SITES REPORTING VISIBILITIES FROM 1/4SM AT KHLC TO 2.5SM AT KCBK. LATEST 03Z RUC/HRRR AND LOCAL WRF MODEL ALL AGREE THAT THE DENSE FOG ALONG OUR FAR EASTERN FORECAST AREA WILL PUSH WESTWARD THROUGH THE REST OF THE NIGHT AND CONTINUE THROUGH THE MORNING MONDAY. UPDATE ISSUED AT 745 PM MST SUN JAN 27 2013 KNRN (NORTON) REPORTING 1/4SM FG AT PRESENT TIME WHILE KHLC (HILL CITY) AT 3SM. FORECAST CONCERNS FOR THE OVERNIGHT HOURS INTO EARLY MONDAY MORNING REVOLVE AROUND EXTENT OF FOG AND THREAT FOR DENSE FOG. HAVE BEEFED UP COVERAGE OF FOG WITH WIDESPREAD FOG EXPECTED FROM ROUGHLY TRENTON OR MCCOOK SOUTH THROUGH OAKLEY AND GOVE TONIGHT INTO EARLY MONDAY MORNING WHERE WINDS REMAIN LIGHT AND DECOUPLING OCCURS. GIVEN THE OBSERVATIONS AT KNRN AT 1/4SM ALREADY HARD TO DISCOUNT THE NEED FOR A DENSE FOG ADVISORY. WILL WATCH FOR TRENDS AND EVALUATE 03Z RUC/LATEST HRRR MODEL RUNS BEFORE MAKING A DECISION. OTHERWISE SHOULD BE GENERALLY CLEAR OUTSIDE OF THE FOG ALTHOUGH SOME MID AND HIGH CLOUDS START TO MOVE INTO FAR EASTERN COLORADO TOWARD SUNRISE AND SLOWLY INCREASE IN COVERAGE DURING THE DAY. && .SHORT TERM...(THIS EVENING THROUGH MONDAY EVENING) ISSUED AT 1258 PM MST SUN JAN 27 2013 LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW POSITIVELY TILTED TROUGH EXTENDING FROM BRITISH COLUMBIA TO CENTRAL CALIFORNIA...WITH SW FLOW ACROSS THE INTER-MOUNTAIN WEST AND CENTRAL PLAINS. SUBSIDENCE IS IN PLACE OVER CENTRAL KS AND CENTRAL CO WITH SEVERAL WEAK SHORTWAVES OVER THE NORTHERN PLAINS. A SURFACE TROUGH IS IN PLACE OVER THE CWA WITH A STALLED WARM FRONT JUST NORTHEAST OF THE CWA IN CENTRAL NEBRASKA. AREAS OF FOG/STRATUS MAY REDEVELOP OVERNIGHT TONIGHT PRIMARILY ALONG THE STATIONARY FRONT IN NEBRASKA...AND THEN SPREAD SW INTO OUR CWA. MOST GUIDANCE IS KEEPING FOG TO THE NORTH AND EAST OF THE CWA...HOWEVER LATEST 24HR RUC IS SHOWING FOG/STRATUS OVERSPREADING THE NE HALF OF CWA. WITH HIGHER TD VALUES POSSIBLY LINGERING ACROSS THE NE HALF OF THE CWA AND LOW LEVELS DECOUPLING...THE RUC SOLUTION SEEMS REASONABLE. ACROSS THE WEST AND SOUTH THE BL SHOULD BEGIN TO DRY OUT OVERNIGHT WITH S/SW FLOW...SO FOG POTENTIAL SHOULD BE MINIMAL CLOSER TO THE KS/CO STATE LINE. AS UPPER LEVEL TROUGH IN THE WEST SHIFTS WEST AND ASSOCIATED COLD FRONT PUSHES SOUTHEAST MONDAY...LEE TROUGH WILL STRENGTHEN WITH STRONG WAA AND BREEZY CONDITIONS ACROSS THE CWA. HIGH TEMP FORECAST IS COMPLICATED BY THE POSSIBILITY OF LINGERING STRATUS...AND INCREASING CLOUDS AS COLD FRONT AND UPPER TROUGH APPROACH CWA LATER IN THE AFTERNOON. WE COULD ALSO START TO SEE RAIN CHANCES INCREASE LATE IN THE AFTERNOON ACROSS THE NORTH/NORTHWEST. FOR NOW I KEPT HIGH TEMPS IN LINE WITH PREVIOUS FORECAST...WITH NEAR RECORD HIGHS IN THE MID TO UPPER 60S ACROSS NW KANSAS...AND SLIGHTLY COOLER TEMPS ACROSS THE NORTH. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 1258 PM MST SUN JAN 27 2013 LONGWAVE TROUGH WILL BRING A CHANCE OF LIGHT SNOW TO MOST OF THE AREA MONDAY NIGHT. BEST CHANCES WILL BE BEFORE MIDNIGHT...THEN GRADUALLY WINDING DOWN THROUGH TUESDAY MORNING. TOTAL SNOW AMOUNTS STILL ON TRACK TO BE AN INCH OR LESS...HIGHEST IN COLORADO. NORTHWEST FLOW ALOFT WILL BE IN PLACE THE REMAINDER OF THE PERIOD. VERY WEAK SYSTEM MAY BRING FLURRIES OR A LIGHT DUSTING WEDNESDAY NIGHT AND THURSDAY...OTHERWISE IT WILL BE DRY. TEMPERATURES WILL BE NEAR TO SLIGHTLY BELOW NORMAL EARLY IN THE PERIOD...BUT WARM TO AROUND 10 DEGREES ABOVE NORMAL BY THE WEEKEND. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1000 PM MST SUN JAN 27 2013 FOR KGLD...SOUTH TO SOUTHWEST WINDS AROUND 10KTS EXPECTED THROUGH LATE MORNING MONDAY BEFORE INCREASING INTO THE 17G27KT RANGE BY 17Z AHEAD OF AN APPROACHING COLD FRONT. SHOULD SEE A DECREASE IN WIND AROUND 00Z BEFORE SHIFTING TO THE NORTHWEST AROUND 04Z WITH GUSTS AROUND 20KTS POSSIBLE. FIRST IMPACT TO AN OTHERWISE VFR FORECAST IS STRATUS/FOG THAT IS FORECAST TO BACK IN TOWARD THE TERMINAL IN THE 12Z-16Z TIMEFRAME. GIVEN THE MODELS GENERALLY DONT GO FAR ENOUGH WEST WITH THE MOISTURE HAVE A TEMPO GROUP FOR VIS AROUND 4SM. NEXT CHANCE FOR MVFR/IFR CONDITIONS WILL BE IMMEDIATELY BEHIND THE FRONT MONDAY NIGHT WHERE CIGS AROUND 1500FT EXPECTED. FOR KMCK...CURRENTLY SEEING VFR CONDITIONS WITH VIS AROUND 4SM IN MIST. CONFIDENCE IS HIGHER THAT CONDITIONS WILL DETERIORATE TO IFR/VLIFR BY 10Z AND CONTINUE THROUGH 16Z OR SO IN FG WITH VIS AROUND 1/4 MILE. CONDITIONS SHOULD RETURN TO VFR SHORTLY AFTER 16Z ONLY TO FALL BACK INTO THE MVFR/IFR RANGE AFTER 02Z AS A COLD FRONT MOVES THROUGH. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL NOON CST MONDAY FOR KSZ002>004-014>016- 028-029. CO...NONE. NE...DENSE FOG ADVISORY UNTIL NOON CST MONDAY FOR NEZ080-081. && $$ UPDATE...99 SHORT TERM...DR LONG TERM...024 AVIATION...99
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1002 PM MST SUN JAN 27 2013 .UPDATE... ISSUED AT 745 PM MST SUN JAN 27 2013 KNRN (NORTON) REPORTING 1/4SM FG AT PRESENT TIME WHILE KHLC (HILL CITY) AT 3SM. FORECAST CONCERNS FOR THE OVERNIGHT HOURS INTO EARLY MONDAY MORNING REVOLVE AROUND EXTENT OF FOG AND THREAT FOR DENSE FOG. HAVE BEEFED UP COVERAGE OF FOG WITH WIDESPREAD FOG EXPECTED FROM ROUGHLY TRENTON OR MCCOOK SOUTH THROUGH OAKLEY AND GOVE TONIGHT INTO EARLY MONDAY MORNING WHERE WINDS REMAIN LIGHT AND DECOUPLING OCCURS. GIVEN THE OBSERVATIONS AT KNRN AT 1/4SM ALREADY HARD TO DISCOUNT THE NEED FOR A DENSE FOG ADVISORY. WILL WATCH FOR TRENDS AND EVALUATE 03Z RUC/LATEST HRRR MODEL RUNS BEFORE MAKING A DECISION. OTHERWISE SHOULD BE GENERALLY CLEAR OUTSIDE OF THE FOG ALTHOUGH SOME MID AND HIGH CLOUDS START TO MOVE INTO FAR EASTERN COLORADO TOWARD SUNRISE AND SLOWLY INCREASE IN COVERAGE DURING THE DAY. && .SHORT TERM...(THIS EVENING THROUGH MONDAY EVENING) ISSUED AT 1258 PM MST SUN JAN 27 2013 LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW POSITIVELY TILTED TROUGH EXTENDING FROM BRITISH COLUMBIA TO CENTRAL CALIFORNIA...WITH SW FLOW ACROSS THE INTER-MOUNTAIN WEST AND CENTRAL PLAINS. SUBSIDENCE IS IN PLACE OVER CENTRAL KS AND CENTRAL CO WITH SEVERAL WEAK SHORTWAVES OVER THE NORTHERN PLAINS. A SURFACE TROUGH IS IN PLACE OVER THE CWA WITH A STALLED WARM FRONT JUST NORTHEAST OF THE CWA IN CENTRAL NEBRASKA. AREAS OF FOG/STRATUS MAY REDEVELOP OVERNIGHT TONIGHT PRIMARILY ALONG THE STATIONARY FRONT IN NEBRASKA...AND THEN SPREAD SW INTO OUR CWA. MOST GUIDANCE IS KEEPING FOG TO THE NORTH AND EAST OF THE CWA...HOWEVER LATEST 24HR RUC IS SHOWING FOG/STRATUS OVERSPREADING THE NE HALF OF CWA. WITH HIGHER TD VALUES POSSIBLY LINGERING ACROSS THE NE HALF OF THE CWA AND LOW LEVELS DECOUPLING...THE RUC SOLUTION SEEMS REASONABLE. ACROSS THE WEST AND SOUTH THE BL SHOULD BEGIN TO DRY OUT OVERNIGHT WITH S/SW FLOW...SO FOG POTENTIAL SHOULD BE MINIMAL CLOSER TO THE KS/CO STATE LINE. AS UPPER LEVEL TROUGH IN THE WEST SHIFTS WEST AND ASSOCIATED COLD FRONT PUSHES SOUTHEAST MONDAY...LEE TROUGH WILL STRENGTHEN WITH STRONG WAA AND BREEZY CONDITIONS ACROSS THE CWA. HIGH TEMP FORECAST IS COMPLICATED BY THE POSSIBILITY OF LINGERING STRATUS...AND INCREASING CLOUDS AS COLD FRONT AND UPPER TROUGH APPROACH CWA LATER IN THE AFTERNOON. WE COULD ALSO START TO SEE RAIN CHANCES INCREASE LATE IN THE AFTERNOON ACROSS THE NORTH/NORTHWEST. FOR NOW I KEPT HIGH TEMPS IN LINE WITH PREVIOUS FORECAST...WITH NEAR RECORD HIGHS IN THE MID TO UPPER 60S ACROSS NW KANSAS...AND SLIGHTLY COOLER TEMPS ACROSS THE NORTH. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 1258 PM MST SUN JAN 27 2013 LONGWAVE TROUGH WILL BRING A CHANCE OF LIGHT SNOW TO MOST OF THE AREA MONDAY NIGHT. BEST CHANCES WILL BE BEFORE MIDNIGHT...THEN GRADUALLY WINDING DOWN THROUGH TUESDAY MORNING. TOTAL SNOW AMOUNTS STILL ON TRACK TO BE AN INCH OR LESS...HIGHEST IN COLORADO. NORTHWEST FLOW ALOFT WILL BE IN PLACE THE REMAINDER OF THE PERIOD. VERY WEAK SYSTEM MAY BRING FLURRIES OR A LIGHT DUSTING WEDNESDAY NIGHT AND THURSDAY...OTHERWISE IT WILL BE DRY. TEMPERATURES WILL BE NEAR TO SLIGHTLY BELOW NORMAL EARLY IN THE PERIOD...BUT WARM TO AROUND 10 DEGREES ABOVE NORMAL BY THE WEEKEND. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1000 PM MST SUN JAN 27 2013 FOR KGLD...SOUTH TO SOUTHWEST WINDS AROUND 10KTS EXPECTED THROUGH LATE MORNING MONDAY BEFORE INCREASING INTO THE 17G27KT RANGE BY 17Z AHEAD OF AN APPROACHING COLD FRONT. SHOULD SEE A DECREASE IN WIND AROUND 00Z BEFORE SHIFTING TO THE NORTHWEST AROUND 04Z WITH GUSTS AROUND 20KTS POSSIBLE. FIRST IMPACT TO AN OTHERWISE VFR FORECAST IS STRATUS/FOG THAT IS FORECAST TO BACK IN TOWARD THE TERMINAL IN THE 12Z-16Z TIMEFRAME. GIVEN THE MODELS GENERALLY DONT GO FAR ENOUGH WEST WITH THE MOISTURE HAVE A TEMPO GROUP FOR VIS AROUND 4SM. NEXT CHANCE FOR MVFR/IFR CONDITIONS WILL BE IMMEDIATELY BEHIND THE FRONT MONDAY NIGHT WHERE CIGS AROUND 1500FT EXPECTED. FOR KMCK...CURRENTLY SEEING VFR CONDITIONS WITH VIS AROUND 4SM IN MIST. CONFIDENCE IS HIGHER THAT CONDITIONS WILL DETERIORATE TO IFR/VLIFR BY 10Z AND CONTINUE THROUGH 16Z OR SO IN FG WITH VIS AROUND 1/4 MILE. CONDITIONS SHOULD RETURN TO VFR SHORTLY AFTER 16Z ONLY TO FALL BACK INTO THE MVFR/IFR RANGE AFTER 02Z AS A COLD FRONT MOVES THROUGH. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...99 SHORT TERM...DR LONG TERM...024 AVIATION...99
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
832 PM EST TUE JAN 29 2013 .Mesoscale Forecast Update... Issued at 830 PM EST Tue Jan 30 2013 Surface low is beginning to strengthen across Missouri as upper-level energy pushes eastward. As of 800 PM, the cold front extends southwest from Lake Michigan, through Illinois, Missouri, and into Oklahoma. Convection has been ongoing this afternoon and evening ahead of the front. While there were severe storms that impacted the St. Louis metropolitan area earlier, but this has diminished in strength as it currently pushes into central Illinois. The airmass across central Illinois and into our area is still fairly stable. Aircraft soundings confirm what the models have been predicting, which is a low-level inversion. The main concern is the convection ongoing across south-central Missouri and northern Arkansas, which is showing better signs of organizing. As indicated with the latest Mesoscale Discussion from SPC, this will likely be the line that will continue to propagate east impacting our area overnight. As this line approaches, the cap will weaken as theta-e advection increases, which is evident with a few low-topped showers developing around the region. As advertised for several days now, the shear will be quite impressive as the line gets into our area. Effective bulk shear currently ahead of the line (across western KY) is 55+ knots, with effective SRH up to about 500 m2/s2. All guidance continues to peg high shear in a weakly unstable environment for us as this convective line gets into our area. With the surface low strengthening as it tracks northeast and 55+ knot winds at 1900 ft AGL, would expect the severe potential to continue into southern Indiana/central Kentucky. Damaging winds with the line will be the main threat as it becomes better organized over the next few hours. Embedded circulations within bowing segments will continue to be a threat as well, so isolated tornadoes remain in play. Overall timing has not changed, with models still showing slight timing differences. Latest RAP is a tad slower than our current forecast, but if the line surges with better cold pool forcing, then we are pretty much on schedule. Aside from the strong winds associated with the convection, gradient winds continue to strengthen. Some gusts are currently around 30 knots, with stronger winds likely as this system approaches. && .Short Term (Tonight through Wednesday Night)... Issued at 320 PM EST Tue Jan 29 2013 ...Strong to Severe Storms Expected Early Wednesday Morning With Wind Damage and Isolated Tornadoes Being The Main Threats... Models continue to remain in good agreement on severe weather threat for tonight, and upstream development is matching up well with high-res forecasts. MSAS analysis at 19Z indicated a broad 998 mb low, stretching from eastern OK to southwest MO. By 06Z tonight, models forecast this low to drop to around 990 mb near KLOT and continuing to deepen towards daybreak. A powerful low-level jet will develop overnight in response to this deepening. Models continue to indicate this jet will be on the order of 70-80 knots at 850 mb. Gradient winds ahead of the main line still are expected to be fairly gusty. Speeds are marginal for a wind advisory, but guidance usually does not handle nighttime winds as well in these situations, so will continue the wind advisory. Temperatures remaining in the 60s through the night will mean that a squall line that forms out of the storms to our west this afternoon will find a favorable environment to maintain itself through the forecast area. Low level wind shear is mostly unidirectional, but storm relative helicities are very high. We may see some discrete cells develop ahead of the line which would be able to take more advantage of more southerly winds ahead of the line to produce tornadoes. The line itself likely will produce damaging winds as the strong winds aloft get mixed down. Also cannot rule out some embedded tornadoes within the line in the stronger meso`s that form. The threat for flash flooding seems less with each run, as the width of the band thins out some. For now have QPF for the tonight/Wednesday time period at around an inch, though isolated higher amounts are possible. Area rivers should be able to handle this water. Guidance for winds behind the main line pick up again Wednesday afternoon. Should we get any breaks in the clouds, we easily could see another round of 30-40 knot winds, so current timing on the wind advisory looks good. The cold front associated with this low pressure system will not get into the region until late in the afternoon Wednesday. West/northwest winds will stay up Wednesday night as much colder air pours into the area. We may see a brief period of snow as lingering precipitation ahead of the main upper trough and nearer the front remains into the night. Accumulations look minor at this point, mainly over the Bluegrass if at all. .Long Term (Thursday through Tuesday)... Issued at 325 PM EST Tue Jan 29 2013 A shortwave and weak surface boundary looks to move through the Ohio Valley Thursday afternoon/evening, bringing a slight chance for light rain/snow showers to south-central Indiana. Once the temperatures drop below freezing that night, expect any rain showers to change over to snow completely as central Kentucky and southern IN gets locked under a cold, Canadian airmass. Since models appear to be trending a bit cooler, have dropped min temps Thursday overnight/Friday morning into the upper teens and lower 20s. These temps don`t look to rebound above the freezing mark on Friday afternoon so look for clearing skies as the disturbance moves off toward the east and surface high pressure briefly drops in. The next disturbance appears to begin affecting the northern and western portions of the forecast area by Saturday morning with light snow shower chances for the north and light rain showers elsewhere. As the temps rise above freezing, any snow that does fall early on should switch over to mostly rain as the entire thermal profile warms up. Even though temps will fall back into the 20s overnight Saturday, the precip should exit to the east before approaching the freezing mark again. For the remainder of the weekend, southerly flow will return to the region, warming temps into the 40s and 50s Sunday-Monday. However, the rain is anticipated to return ahead of a cold front Monday in the form of rain. The rain should be out by the start of the day on Tuesday with the frontal passage. This leads temps to take on a non-diurnal curve on Tuesday as the warmest temps of the day should occur early on. As always is the case for this time of year, any changes to the thermal profile forecast could change precip types but for now, there appears to be general model consensus in the anticipated overall pattern for this time frame. Any snow that is able to stick to surfaces should be very light in accumulations. && .Aviation (00Z TAF Issuance)... Issued at 642 PM EST Tue Jan 29 2013 Deep upper-level trough over the Eastern Rockies will force a surface low pressure system now over the southern Plains to intensify and head quickly toward the Midwest this evening and overnight. The pressure gradient is beginning to tighten ahead of this low, with southerly winds starting to increase/gust. Latest wind profile guidance from CWSU ZSE indicates low-level wind shear is likely overnight, with 50-60 knots around 1900 feet AGL. So, will continue LLWS for all TAF sites. Convection currently across Illinois, Missouri, and Arkansas will form a more organized line of thunderstorms as the surface low strengthens tonight. This line will eventually move east through all TAF sites. Have put in the best thoughts for timing the actual line. Added VCTS a couple hours prior to account for any development ahead of the line. Some guidance indicates there could be two lines of convection. Will hit the TAFs harder when the line does approach. Expect MVFR cigs through most of the night, with conditions not improving until mid-late morning Wednesday. By late Wednesday afternoon, there could be low-topped showers/thunderstorms on the back side of this system, so will continue with VCSH through the end of the TAF period for now. && .Hydrology... Issued at 300 AM EST Tue Jan 29 2013 No real changes in the forecast thinking on the hydrologic front. An intense line of strong to severe thunderstorms is forecast to move across the region late tonight and early Wednesday morning. In addition to the threat of damaging winds, these storms will likely produce heavy rainfall. Once the system pulls east on Wednesday morning, a period of stratiform rainfall will likely persist for a few hours. Rainfall amounts averaging a little more than an inch in 6 hours should be widespread. Isolated amounts of up to 2 inches are possible. This rain could result in brief small stream flooding and later rises on larger rivers. Any flooding that will occur should be minor due to the fast nature of these storms. The rain will taper to scattered showers Wednesday afternoon. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...WIND ADVISORY UNTIL 4 PM EST /3 PM CST/ WEDNESDAY FOR INZ076>079- 083-084-089>092. KY...WIND ADVISORY UNTIL 4 PM EST /3 PM CST/ WEDNESDAY FOR KYZ023>032- 061-062-070>072. WIND ADVISORY UNTIL 7 PM EST /6 PM CST/ WEDNESDAY FOR KYZ033>043- 045>049-053>057-063>067-073>078-081-082. $$ Mesoscale........MJP Short Term.......RJS Long Term........lg Aviation.........MJP Hydrology........MJ/CMC
AREA FORECAST DISCUSSION
NWS JACKSON KY
1231 AM EST MON JAN 28 2013 .UPDATE... ISSUED AT 638 PM EST SUN JAN 27 2013 LIGHT RAIN IS BECOMING MORE WIDESPREAD ACROSS CENTRAL KENTUCKY AND HAVE OPTED TO INCREASE POPS UP TO NEAR 100 FOR MOST OF EASTERN KENTUCKY TONIGHT GIVEN WHAT IS TAKING PLACE UPSTREAM. NEARLY ALL MESONET/AWOS/ASOS OBSERVATIONS ARE RECORDING MEASURABLE RAIN...SO IT LOOKS LIKE A SURE BET WE WILL SEE WIDESPREAD LIGHT RAIN THROUGH MIDNIGHT. IT STILL LOOKS LIKE THINGS SHOULD TAIL OFF SHORTLY AFTER MIDNIGHT. FORECAST UPDATE IS ALREADY OUT. UPDATE ISSUED AT 534 PM EST SUN JAN 27 2013 UPDATED TO SLOW DOWN PRECIPITATION ONSET. IT LOOKS LIKE THINGS ARE FINALLY STARTING TO SATURATE UP ENOUGH TO ALLOW FOR SOME LIGHT RAIN IN THE MONTICELLO/SOMERSET AREA SHORTLY. OTHERWISE...IT WILL REMAIN A SLOW PROCESS AS RAIN TRIES TO FIGHT TO THE LOW LEVEL DRY AIR. THE RAIN SHOULD EVENTUALLY WIN OUT...BUT STILL QUESTIONABLE IF THE SOUTHEAST WILL SEE MUCH IN THE WAY OF RAIN AS THERE WILL LIKELY BE A SOUTHEAST TO NORTHWEST GRADIENT FOR PLACES THAT RECEIVE RAIN VERSES THOSE WHO DO NOT. BASED ON LATEST RUC MODEL DATA...RAIN SHOULD BE ON THE WAY OUT BY 06Z WITH DRIER CONDITIONS EXPECTED FOR THE SECOND HALF OF THE NIGHT INTO TOMORROW MORNING. && .SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT) ISSUED AT 310 PM EST SUN JAN 27 2013 CURRENT CONDITIONS ACROSS EASTERN KENTUCKY AS OF 20Z HAS PRECIP BEGINNING TO ENTER THE AREA NEAR SOMERSET AHEAD OF A DEVELOPING WARM FRONT. AT THIS POINT...SURFACE OBS HAVE SHOWN NO PRECIP MAKING IT TO THE GROUND IN THE SOUTH. BASED ON THE PERSISTENCE OF THE MODELS BRINGING IN THE PRECIP LATE THIS AFTERNOON AND INTO THE EARLY EVENING...WILL KEEP A SLIGHT CHANCE INTO THIS EARLY AFTERNOON WITH THE RAIN OVER SPREADING THE REST OF EASTERN KENTUCKY THIS EVENING. EXPECT RAIN TO CONTINUE THROUGH THE NIGHT. CONCERNS WITH THE TIMING OF THE PASSING WARM FRONT LOOK TO BE AROUND 12Z WITH A 30 TO 40 KNOT LL JET OVERHEAD. THIS WILL LEAD TO SOME 20 KNOT SOUTHWEST WINDS MIXING TO THE SURFACE FOR MONDAY. MORE SHOWERY PRECIP ENTERS THE AREA BY MONDAY AFTERNOON AS EASTERN KENTUCKY WILL BE IN THE WARM SECTOR FOR THE REST OF THE SHORT TERM. THE SURGE OF WARM AIR WILL BRING HIGHS FOR MONDAY INTO THE LOWER 60S...NEARLY 5 DEGREES SHORT OF RECORD VALUES. SHOWER ACTIVITY WILL CONTINUE THROUGH MONDAY NIGHT AS WELL WITH MODELS HANDLING THE SET UP QUITE WELL. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 351 PM EST SUN JAN 27 2013 THE MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE TIMING OF THE NEXT FRONT. THE LEADING EDGE OF THE FRONT IS GOING TO BRING SOME SHOWERS TO THE BLUEGRASS ON TUESDAY MORNING. AS THE FRONT GETS NEARER...SHOWERS WILL SPREAD ACROSS EASTERN KENTUCKY DURING THE TUESDAY EVENING. THE LATEST ECMWF IS SLOWING THIS DOWN A LITTLE...SO WILL NOT BE SURPRISED TO SEE THE FRONT SLOW DOWN AS THE TIME GETS NEARER. THE FRONT WILL ACTUALLY BE MOVING THROUGH THE AREA ON WEDNESDAY MORNING. THE NAM BUFR WAS SHOWING THE BEST INSTABILITY TO BE VERY NEAR THE FRONT ITSELF AND THIS IS WHERE THUNDERSTORMS WILL BE MOST LIKELY. THERE IS VERY STRONG SHEAR WITH THE FRONT...HOWEVER THE INSTABILITY IS MARGINAL...SO THE SEVERE POTENTIAL IS LOW...BUT NOT ZERO. IF THE FRONT SLOWS DOWN...THE THE SEVERE POTENTIAL WILL BE GREATER. WILL NEED TO BE VIGILANT TO SEE HOW THIS PLAYS OUT. ONCE THE POST FRONTAL SHOWERS MOVE INTO WEST VIRGINIA BY TUESDAY MORNING...THE WILL BE A SHORT RESPITE...UNTIL A CLIPPER SYSTEM MOVES THROUGH THE AREA ON THURSDAY NIGHT. THE LOOKS TO BE A LIGHT SNOWFALL WITH ABOUT AN INCH EXPECTED. THIS WOULD BE A STUDENTS DREAM AND GIVE THEM ANOTHER THREE DAY WEEKEND. HIGH PRESSURE WILL THEN DOMINATE UNTIL ANOTHER WEAK SYSTEM MOVES THROUGH THE AREA ON SATURDAY NIGHT. SO THIS WILL BE AN ACTIVE PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1230 AM EST MON JAN 28 2013 AN AREA OF LIGHT RAIN SHOWERS WILL CONTINUE TO MOVE OUT OF EASTERN KENTUCKY DURING THE OVERNIGHT HOURS. MOST OF THE RAIN NOW IS MOVING ACROSS AN AREA NORTH OF A LINE FROM PIKEVILLE TO JACKSON TO STANTON. BASED ON THE LATEST RADAR IMAGERY...THIS TREND WILL CONTINUE FOR THE NEXT COUPLE OF HOURS...BY WHICH TIME MOST OR ALL OF THE RAIN SHOWERS WILL HAVE MOVED OUT OF THE FORECAST AREA FOR THE NIGHT. THE NEXT SHOT OF RAIN WILL ARRIVE IN THE AREA BETWEEN 17 AND 18Z TOMORROW...WITH THE TAF SITES SEEING ACCUMULATING RAIN BETWEEN 20 AND 21Z. MVFR CONDITIONS ARE EXPECTED TO PREVAIL AT THE TAFS SITES FOR THE NEXT FEW HOURS AS WELL...BEFORE THE LOWER CLOUDS BREAKUP A BIT...GIVING WAY TO BROKEN TO OVERCAST CLOUD LAYERS ABOVE 10K. A FEW TO SCATTERED LOW AND MIDDLE LEVEL CLOUDS WILL LIKELY DRIFT ACROSS THE SKIES NEAR THE OR AT THE TAF SITES UNTIL THE NEXT ROUND OF RAIN MOVES MONDAY AFTERNOON. THE NEXT SHOT OF RAIN WILL BRING BORDERLINE MVFR CONDITIONS WITH IT AS WELL. TOWARD THE END OF THE TAF PERIOD...FOG FORMATION WILL LEAD TO MVFR CONDITIONS ONCE AGAIN AFTER THE NEXT ROUND OF RAIN MOVES OUT OF THE AREA. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KAS SHORT TERM...SHALLENBERGER LONG TERM....JJ AVIATION...AR
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
132 PM EST MON JAN 28 2013 .SYNOPSIS... A WARM FRONT LIFTS NORTH OF THE AREA THROUGH EARLY THIS AFTERNOON. THE NEXT COLD FRONTAL PASSAGE IS EXPECTED LATE WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... TEMPS HAVE RISEN ABOVE FREEZING THIS MORNING...ALLOWING LIGHT PRECIP TO BECOME MOSTLY RAIN...EXCEPT FOR A FEW REPORTS OF SLEET ACROSS SE VA/NE NC. HAVE ALLOWED THE FREEZING RAIN ADVISORY TO EXPIRE AS PLANNED THIS MORNING. AS THE WARM FRONT CONTINUES TO LIFT TO THE NORTH AND THE SHORTWAVE PUSHES OFFSHORE...PRECIP WILL QUICKLY COME TO AN END W TO E. LATEST RADAR RETURNS/OBS SHOW PRECIP ALREADY ENDING ALONG AND W OF INTERSTATE 95. PRECIP EXPECTED TO END ACROSS THE ERN FA AROUND NOON. ANOTHER WEAKER SHORTWAVE/VORT MAX WILL TRACK THROUGH NRN VA THIS AFTERNOON...RESULTING ADDITIONAL LIGHT PRECIP FOR THE NRN PORTIONS OF THE ERN SHORE. TEMPS WILL BE TRICKY TODAY RESULTS IN ABUNDANT CLOUD COVER/WEAK MIXING IS EXPECTED TO TRUMP LOW LEVEL WAA. LOW LEVEL THICKNESS VALUES FORECAST TO INCREASE 10M BY LATE AFTERNOON WITH H85 TEMPS INCREASING TO AROUND +8C. WAA VISIBLE ON MORNING KWAL SOUNDING PER AN INCREASE IN 850 TEMPS OF 15C OVER THE PAST 24 HRS. MADE MINOR CHANGES TO THE INHERITED DAYTIME HIGHS...BUMPING TEMPS DOWN A DEG OR TWO ACROSS THE W. OF INTEREST...LATEST RAP GUIDANCE ERODES THE CLOUD DECK OVER THE PIEDMONT...ALLOWING TEMPS TO CLIMB INTO THE MID 50S. HOWEVER...LATEST BUFR SOUNDINGS AND WAA SUGGESTS THIS CLOUD COVER/WEDGE SETUP WILL GO NOWHERE OVERNIGHT. TEMPS FORECAST TO ONLY FALL INTO THE LOW/MID 40S. CONTINUED WAA OVERNIGHT ALONG WITH MOIST SOILS AND WEAK MIXING WILL RESULT IN AREAS OF DENSE FOG/LOW STRATUS TONIGHT. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... WARM AIR QUICKLY STREAMS INTO THE AREA AS WARM FRONT SURGES NORTHWARD. WITH WEAK MIXING EXPECTED MON NIGHT AND EARLY ON TUESDAY WL NEED TO WATCH PROGRESS OF WEDGE ACROSS THE NORTHWEST, BUT FOR NOW INCRIMENTALLY NUDGED TEMPS UPWARDS. OTHERWISE, ONCE LLVL INVERSION GETS BROKEN, EXPECT MARKEDLY WARMER CONDS ON TUESDAY AS SFC HIGH NUDGES FARTHER OFFSHORE AND WARM SW FLOW SETS UP. LO TEMPS TNGT MNLY IN THE L/M40S. HIGHS TUE FM THE U50S TO M60S. LO TEMPS TUE NGT FM THE M/U40S ON THE ERN SHR TO L/M50S ELSW. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... STRONG SHORTWAVE TROUGH AND ASSOCIATED SFC LOW WILL EJECT FROM THE DEEP SOUTH INTO THE MID ATLANTIC REGION WEDNESDAY AFTERNOON. SFC LOW WILL LOCATE OVER THE GREAT LAKES WITH THE COLD FRONT EXTENDING SW INTO THE LOWER MS RIVER VALLEY. WHILE TIMING AND SPATIAL DIFFERENCES STILL EXIST...ECMWF MORE AMPLIFIED AND SLIGHTLY SLOWER THAN GFS...A WARM/WET/WINDY DAY IS ON TAP FOR THE FA. DEEP SWLY FLOW WILL RESULT IN STRONG MOISTURE ADVECTION INTO THE REGION...ORIGINATING FROM THE GULF OF MEXICO (EVIDENT IN 700MB THETA E RIDGE). PRECIP WATERS WILL INCREASE TO AROUND 1.5" (OVER 2 STD ABOVE NORMAL FOR JANUARY). COLD FRONT EXPECTED TO CROSS THE FA WED LATE AFTERNOON THROUGH LATE WED NIGHT. DIVERGENCE ALOFT (RRQ OF 160+ KT 300MB JET) AND VORT MAX/SHORTWAVE WILL PROVIDE FORCING FOR ASCENT ACROSS THE REGION. MARGINAL LAPSE RATES...SHEAR AND LITTLE...IF ANY CAPE IN THE MIXED PHASE LAYER WILL LIKELY LIMIT CHANCE OF THUNDER WEDS AFTERNOON. WILL LEAVE OUT ANY MENTION OF THUNDER IN THE GRIDS/ZONES FOR NOW...BUT MAY NEED TO BE ADDED LATER WHEN MODELS HAVE A BETTER HANDLING ON THE DEVELOPING SYSTEM. HAVE INCREASED POPS TO CATEGORICAL WEDS AFTERNOON/EVENING ACROSS THE REGION. LIGHT SHOWERS WILL BE POSSIBLE WEDS MORNING/EARLY AFTERNOON ACROSS THE PIEDMONT. ABUNDANT MOISTURE AND STRONG FRONTOGENETIC FORCING COULD ALSO LEAD TO PERIODS OF MODERATE TO HEAVY RAINFALL ACROSS THE REGION. QPF AMOUNTS FORECAST TO GENERALLY RANGE FROM ONE QUARTER TO ONE HALF INCH WITH LOCALLY HIGHER AMOUNTS. PRECIP WILL END QUICKLY W TO E EARLY THURS MORNING AS DEEP...DRY WLY FLOW KICKS IN. STRONG WAA AND INCREASING HEIGHT/THICKNESS VALUES IN ADVANCE OF THE FRONT (850 TEMPS WARMING TO NEAR +14C) WILL RESULT IN A WARM/HUMID DAY. WHILE DAYTIME MIXING WILL BE WEAK WITH LACK OF SUNSHINE...BL WINDS WILL BE ENOUGH FOR SLY SFC WINDS 15 TO 20 MPH WITH GUSTS UP TO 25 MPH. WHILE CLOUD COVER/LACK OF STRONG MIXING WILL LIMIT TEMPS FROM REACHING THEIR FULL POTENTIAL...HIGHS STILL EXPECTED TO REACH INTO THE UPPER 60S/LOW 70S ACROSS THE FA. IN WAKE OF THE DEPARTING SYSTEM...TROUGHING WILL REMAIN OVER THE REGION THURSDAY AS HEIGHT/THICKNESS FALLS RESULT IN COLDER TEMPS THURSDAY (MID 40S N TO MID 50S). ADDITIONAL ENERGY WILL DIVE DOWN THE BACKSIDE OF THE TROUGH THURS AFTERNOON...LOCATING OVER THE OH VALLEY FRIDAY MORNING AS A WEAK LEE SIDE SFC TROUGH DEVELOPS. MOISTURE MAY BE A CONCERN...BUT HAVE OPTED TO MENTION SLIGHT CHANCE/CHANCE POPS ACROSS THE FA. PTYPE WILL BE A CONCERN...WITH SNOW SHOWERS POSSIBLE ACROSS THE NRN FA. ARCTIC HIGH PRESSURE WILL BUILD OVER THE MID ATLANTIC FRIDAY NIGHT INTO SATURDAY AS A CLIPPER SYSTEM DIVES OVER THE GREAT LAKES EARLY SATURDAY. TEMPS EXPECTED TO REMAIN BELOW NORMAL THROUGH THE WEEKEND. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... PRECIPITATION HAS LIFTED OFF TO THE NE OF THE REGION...AND LOW CLOUDS AND VSBYS HAVE NOW MOVED OUT OF THE TAF SITES (ALTHOUGH IFR CIGS ARE NOT FAR OFF FROM KSBY). EXPECT MAINLY VFR CONDITIONS THROUGH 00Z THIS EVENING...ALTHOUGH SOME MVFR VSBYS MAY PERSIST AT KSBY AND MVFR CIGS MAY BEGIN TO MOVE INTO SE VA/NE NC AFTER 20Z. FOR TONIGHT...DUE TO AMPLE LOW LEVEL MOISTURE WILL TREND THE TAFS DOWN TO IFR CIGS (< 1 K FT) DURING THE EVENING HRS. SW FLOW TYPICALLY INHIBITS VSBYS FROM DROPPING DOWN TOO FAR SO FOR NOW HAVE GENLY GONE WITH 3-5SM (ALTHOUGH IT MAY DROP MORE AFTER MIDNIGHT AND CIGS MAY ALSO DROP DOWN TO < 500 FT). THE LOW LEVEL SW TO W FLOW ON TUESDAY SHOULD GRADUALLY SCOUR OUT LOW LEVEL MOISTURE BUT IT DOES NOT APPEAR THAT STRONG SO MAY TAKE AWHILE (FOR NOW HAVE IFR CIGS IN TAFS THROUGH 16Z). FOG/LOW CLOUDS WILL PROBABLY RETURN FOR SOME OF THE AREA TUE NIGHT. A STRONGER SSW WIND ON WEDNESDAY SHOULD PRODUCE VFR CONDITIONS. THE ARRIVAL OF A COLD FRONT LATE WED AFTN THROUGH EARLY THU MORNING WILL LIKELY PRODUCE MVFR/IFR CONDITIONS IN SHRA. DRIER WNW FLOW THU. && .MARINE... PER LATEST OBS AND TRENDS HAVE ADDED SCA HEADLINES TO MIDDLE BAY ZONE SO NOW THE BAY NORTH OF NEW PT COMFORT IS COVERED W/ SCA HEADLINES. PREVIOUS DISCUSSION... A WARM FRONT WILL LIFT NORTH OF THE REGION LATER THIS MORNING ALLOWING FOR INCREASING SW FLOW. BY THIS AFTERNOON...SW WINDS OF 15-20 KT ARE EXPECTED ON THE OCEAN AND ALSO THE CENTRAL CHES BAY NORTH OF WINDMILL PT AS THE LOW LEVEL PRESSURE GRADIENT TIGHTENS BETWEEN DEPARTING HIGH PRESSURE AND LOW PRESSURE OVER THE EASTERN GREAT LAKES. SOME GUSTS UP TO 25 KT ARE POSSIBLE NORTH OF CHINCOTEAGUE LATE TODAY...BUT HAVE CAPPED WIND GUSTS BELOW SCA THRESHOLDS ATTM AS CONFIDENCE NOT HIGH ENOUGH FOR AN SCA HEADLINE. HOWEVER...HAVE RAISED AN SCA FOR THE CENTRAL CHES BAY NORTH OF WINDMILL AS NEWEST HIGH-RES MODEL DATA INSISTS SW FLOW WILL INCREASE TO 15-20 KT THIS AFTERNOON/EVENING. SW WINDS GRADUALLY TAPER OFF LATE TONIGHT INTO EARLY TUESDAY. LIGHT S-SW FLOW IS ANTICIPATED ON TUESDAY. THE NEXT LOW PRESSURE SYSTEM AND ITS ASSOCIATED COLD FRONT WILL APPROACH THE REGION FROM THE WEST LATE WEDNESDAY. AHEAD OF THE FRONT...A STRONG LOW-LEVEL JET WILL DEVELOP OVER THE REGION AND THE WATERS. WHILE THE STRONGEST WINDS WILL REMAIN ALOFT...ENOUGH WIND SHOULD REACH THE WATER SFC TO WARRANT SCA CONDITIONS OVER ALL WATERS FROM MID-MORNING WED INTO EARLY THURS MORNING. SEAS RAPIDLY BUILD WED AFTERNOON...REACHING 8 TO 10 FT OUT AROUND 20 NM LATE. COLD FRONT EXPECTED TO CROSS THE WATERS EARLY THURS MORNING ACCOMPANIED BY MODEST CAA. UNSETTLED WEATHER WILL CONTINUE THROUGH THE WEEKEND AS A SERIES OF DISTURBANCES CROSS THE WATERS. ADDITIONAL SCA HEADLINES WILL LIKELY BE NEEDED THURSDAY AND FRIDAY...AND POSSIBLY INTO THE WEEKEND. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST TUESDAY FOR ANZ630-631. && $$ SYNOPSIS...ALB NEAR TERM...SAM SHORT TERM...ALB/MAM LONG TERM...SAM AVIATION...LKB MARINE...JDM/LKB
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1116 AM EST MON JAN 28 2013 .SYNOPSIS... LOW PRESSURE CROSSING THE EASTERN GREAT LAKES WILL CAUSE RAINY CONDITIONS TODAY. WARMER TREND IN TEMPERATURES WILL CONTINUE THROUGH WEDNESDAY NIGHT BEFORE A STRONG COLD FRONT PASSES THROUGH AND BRINGS BACK COOLER THAN NORMAL TEMPERATURES BY THE END OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... TEMPERATURES IN THE PAST FEW HOURS HAVE WARMED TO ABOVE FREEZING AND PRECIPITATION HAS TRANSITIONED TO ALL RAIN IN CWA WITH THE EXCEPTION OF EXTREME NORTHEAST COUNTIES AND GARRETT COUNTY. RECENT RADAR SHOWS A BAND OF SHOWERS ACROSS THE OHIO VALLEY INTO PA...THEREFORE HAVE EXTENDED POPS THROUGH THE LATE AFTERNOON ACROSS THE REGION. LATEST RAP MODEL RUN SEEMED TO HAVE A GOOD GENERAL IDEA OF MAX TEMP FOR TODAY AS NAM/GFS SEEMED TOO COOL AND PERHAPS DID NOT PICK UP WELL ON WARM AIR ADVECTION. AS DEW POINTS MOVE ABOVE FREEZING THIS AFTERNOON EXPECT WIDESPREAD FOG TO DEVELOP A LITTLE AFTER SUNSET. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... FRONTAL BOUNDARY WILL TRANSITION NORTHWARD THROUGH TUESDAY WITH SHORTWAVES MOVING NORTHEAST ACROSS THE REGION. TIMING OF ANY PARTICULAR SHORTWAVE WILL BE UNCERTAIN BUT WENT WITH A DECLINE IN POPS TO CHANCE NUMBERS AS THE BOUNDARY IS PROJECTED WELL NORTH OF THE AREA. WIDESPREAD FOG IS ANTICIPATED ON MONDAY NIGHT GIVEN THE COLD GROUND AND DEW POINTS MOVING INTO THE 40S. OTHERWISE...EXPECT A VERY MILD TUESDAY WITH THE REGION UNDER A BROAD RIDGE IN AMPLIFIED FLOW. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... THE LONG TERM FORECAST WAS CONSTRUCTED USING A ECMWF/GFSE BLEND...LEAVING THE UPPER OHIO VALLEY IN AN UNSEASONABLY WARM AND MOIST...SOUTHWESTERLY LOW-LEVEL FLOW TUESDAY NIGHT INTO WEDNESDAY AHEAD OF A STRONG COLD FRONT. AN INITIAL SHORT WAVE WILL PUSH ACROSS THE AREA AHEAD OF THE FRONT...WITH THE CHANCE OF RAIN INCREASING TO CATEGORICAL AS THE FRONT APPROACHES FROM THE WEST ON WEDNESDAY. IN THE WAKE OF THE FRONT...STRONG COLD ADVECTION IS EXPECTED TO QUICKLY CHANGE PRECIPITATION OVER TO SNOW SHOWERS ON WEDNESDAY NIGHT WITH SOME UPSLOPING SNOW ACCUMULATION POSSIBLE INTO THURSDAY. COLD FLOW IS FORECAST TO CONTINUE INTO FRIDAY WITH SNOW SHOWER CHANCES CONTINUING. SUB-ZERO WIND CHILL INDICIES AE POSSIBLE BY EARLY FRIDAY. FOR THE WEEKEND...GFS/ECMWF INDICATE A CLIPPER SYSTEM DIVING SOUTHEASTWARD ACROSS THE GREAT LAKES AND PUSHING INTO THE UPPER OHIO VALLEY. HAVE GONE WITH CHC POPS OVER THE WEEKEND FOR THIS POTENTIAL. && .AVIATION /16Z MONDAY THROUGH FRIDAY/... SFC CHART SHOWS A WARM FRONT WAS WORKING NEWD THRU THE RGN. WINTRY PCPN HAS BEGUN TO SWITCH TO RA FM SW-NE AND THIS SHOULD CONT AS WARMER AIR MOVES IN. ALL FZRA SHOULD BE OVR AT PIT BY 14Z. CONDS HAVE BEEN DCRG TO IFR ACRS MUCH OF THE RGN. CONDS COULD VARY BTWN MVFR AND IFR AT TIMES THRU THE AFTN ALTHOUGH EXPTG IFR TO BE PREDOMINATE COND. LLVL JET MOVG IN WL BRING LLWS CONDS AS WELL THRU LT AFTN...WITH TEMP INVERSION LMTG MXG DOWN OF GUSTS TO THE SFC. IFR EXPTD OVRNT IN LOW CIGS/BR. COULD SEE -DZ BUT KEPT OUT OF FCST ATTM. .OUTLOOK.../MONDAY NIGHT THROUGH FRIDAY/... RESTRICTIONS WL CONT THRU TUE. PERIODIC RESTRICTIONS ARE PSBL WED THRU FRI AS A COLD FRONT MOVES THRU AND COLD NW FLOW DVLPS BEHIND IT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR MDZ001. OH...NONE. PA...WINTER STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR PAZ008- 009-015-016. WINTER WEATHER ADVISORY UNTIL 11 AM EST THIS MORNING FOR PAZ007-013-014-020>023-073>076. WV...WINTER WEATHER ADVISORY UNTIL 11 AM EST THIS MORNING FOR WVZ023-041. && $$
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1011 AM EST MON JAN 28 2013 .SYNOPSIS... A WARM FRONT LIFTS NORTH OF THE AREA THROUGH EARLY THIS AFTERNOON. THE NEXT COLD FRONTAL PASSAGE IS EXPECTED LATE WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... TEMPS HAVE RISEN ABOVE FREEZING THIS MORNING...ALLOWING LIGHT PRECIP TO BECOME MOSTLY RAIN...EXCEPT FOR A FEW REPORTS OF SLEET ACROSS SE VA/NE NC. HAVE ALLOWED THE FREEZING RAIN ADVISORY TO EXPIRE AS PLANNED THIS MORNING. AS THE WARM FRONT CONTINUES TO LIFT TO THE NORTH AND THE SHORTWAVE PUSHES OFFSHORE...PRECIP WILL QUICKLY COME TO AN END W TO E. LATEST RADAR RETURNS/OBS SHOW PRECIP ALREADY ENDING ALONG AND W OF INTERSTATE 95. PRECIP EXPECTED TO END ACROSS THE ERN FA AROUND NOON. ANOTHER WEAKER SHORTWAVE/VORT MAX WILL TRACK THROUGH NRN VA THIS AFTERNOON...RESULTING ADDITIONAL LIGHT PRECIP FOR THE NRN PORTIONS OF THE ERN SHORE. TEMPS WILL BE TRICKY TODAY RESULTS IN ABUNDANT CLOUD COVER/WEAK MIXING IS EXPECTED TO TRUMP LOW LEVEL WAA. LOW LEVEL THICKNESS VALUES FORECAST TO INCREASE 10M BY LATE AFTERNOON WITH H85 TEMPS INCREASING TO AROUND +8C. WAA VISIBLE ON MORNING KWAL SOUNDING PER AN INCREASE IN 850 TEMPS OF 15C OVER THE PAST 24 HRS. MADE MINOR CHANGES TO THE INHERITED DAYTIME HIGHS...BUMPING TEMPS DOWN A DEG OR TWO ACROSS THE W. OF INTEREST...LATEST RAP GUIDANCE ERODES THE CLOUD DECK OVER THE PIEDMONT...ALLOWING TEMPS TO CLIMB INTO THE MID 50S. HOWEVER...LATEST BUFR SOUNDINGS AND WAA SUGGESTS THIS CLOUD COVER/WEDGE SETUP WILL GO NOWHERE OVERNIGHT. TEMPS FORECAST TO ONLY FALL INTO THE LOW/MID 40S. CONTINUED WAA OVERNIGHT ALONG WITH MOIST SOILS AND WEAK MIXING WILL RESULT IN AREAS OF DENSE FOG/LOW STRATUS TONIGHT. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... WARM AIR QUICKLY STREAMS INTO THE AREA AS WARM FRONT SURGES NORTHWARD. WITH WEAK MIXING EXPECTED MON NIGHT AND EARLY ON TUESDAY WL NEED TO WATCH PROGRESS OF WEDGE ACROSS THE NORTHWEST, BUT FOR NOW INCRIMENTALLY NUDGED TEMPS UPWARDS. OTHERWISE, ONCE LLVL INVERSION GETS BROKEN, EXPECT MARKEDLY WARMER CONDS ON TUESDAY AS SFC HIGH NUDGES FARTHER OFFSHORE AND WARM SW FLOW SETS UP. LO TEMPS TNGT MNLY IN THE L/M40S. HIGHS TUE FM THE U50S TO M60S. LO TEMPS TUE NGT FM THE M/U40S ON THE ERN SHR TO L/M50S ELSW. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... STRONG SHORTWAVE TROUGH AND ASSOCIATED SFC LOW WILL EJECT FROM THE DEEP SOUTH INTO THE MID ATLANTIC REGION WEDNESDAY AFTERNOON. SFC LOW WILL LOCATE OVER THE GREAT LAKES WITH THE COLD FRONT EXTENDING SW INTO THE LOWER MS RIVER VALLEY. WHILE TIMING AND SPATIAL DIFFERENCES STILL EXIST...ECMWF MORE AMPLIFIED AND SLIGHTLY SLOWER THAN GFS...A WARM/WET/WINDY DAY IS ON TAP FOR THE FA. DEEP SWLY FLOW WILL RESULT IN STRONG MOISTURE ADVECTION INTO THE REGION...ORIGINATING FROM THE GULF OF MEXICO (EVIDENT IN 700MB THETA E RIDGE). PRECIP WATERS WILL INCREASE TO AROUND 1.5" (OVER 2 STD ABOVE NORMAL FOR JANUARY). COLD FRONT EXPECTED TO CROSS THE FA WED LATE AFTERNOON THROUGH LATE WED NIGHT. DIVERGENCE ALOFT (RRQ OF 160+ KT 300MB JET) AND VORT MAX/SHORTWAVE WILL PROVIDE FORCING FOR ASCENT ACROSS THE REGION. MARGINAL LAPSE RATES...SHEAR AND LITTLE...IF ANY CAPE IN THE MIXED PHASE LAYER WILL LIKELY LIMIT CHANCE OF THUNDER WEDS AFTERNOON. WILL LEAVE OUT ANY MENTION OF THUNDER IN THE GRIDS/ZONES FOR NOW...BUT MAY NEED TO BE ADDED LATER WHEN MODELS HAVE A BETTER HANDLING ON THE DEVELOPING SYSTEM. HAVE INCREASED POPS TO CATEGORICAL WEDS AFTERNOON/EVENING ACROSS THE REGION. LIGHT SHOWERS WILL BE POSSIBLE WEDS MORNING/EARLY AFTERNOON ACROSS THE PIEDMONT. ABUNDANT MOISTURE AND STRONG FRONTOGENETIC FORCING COULD ALSO LEAD TO PERIODS OF MODERATE TO HEAVY RAINFALL ACROSS THE REGION. QPF AMOUNTS FORECAST TO GENERALLY RANGE FROM ONE QUARTER TO ONE HALF INCH WITH LOCALLY HIGHER AMOUNTS. PRECIP WILL END QUICKLY W TO E EARLY THURS MORNING AS DEEP...DRY WLY FLOW KICKS IN. STRONG WAA AND INCREASING HEIGHT/THICKNESS VALUES IN ADVANCE OF THE FRONT (850 TEMPS WARMING TO NEAR +14C) WILL RESULT IN A WARM/HUMID DAY. WHILE DAYTIME MIXING WILL BE WEAK WITH LACK OF SUNSHINE...BL WINDS WILL BE ENOUGH FOR SLY SFC WINDS 15 TO 20 MPH WITH GUSTS UP TO 25 MPH. WHILE CLOUD COVER/LACK OF STRONG MIXING WILL LIMIT TEMPS FROM REACHING THEIR FULL POTENTIAL...HIGHS STILL EXPECTED TO REACH INTO THE UPPER 60S/LOW 70S ACROSS THE FA. IN WAKE OF THE DEPARTING SYSTEM...TROUGHING WILL REMAIN OVER THE REGION THURSDAY AS HEIGHT/THICKNESS FALLS RESULT IN COLDER TEMPS THURSDAY (MID 40S N TO MID 50S). ADDITIONAL ENERGY WILL DIVE DOWN THE BACKSIDE OF THE TROUGH THURS AFTERNOON...LOCATING OVER THE OH VALLEY FRIDAY MORNING AS A WEAK LEE SIDE SFC TROUGH DEVELOPS. MOISTURE MAY BE A CONCERN...BUT HAVE OPTED TO MENTION SLIGHT CHANCE/CHANCE POPS ACROSS THE FA. PTYPE WILL BE A CONCERN...WITH SNOW SHOWERS POSSIBLE ACROSS THE NRN FA. ARCTIC HIGH PRESSURE WILL BUILD OVER THE MID ATLANTIC FRIDAY NIGHT INTO SATURDAY AS A CLIPPER SYSTEM DIVES OVER THE GREAT LAKES EARLY SATURDAY. TEMPS EXPECTED TO REMAIN BELOW NORMAL THROUGH THE WEEKEND. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... A DISTURBANCE CROSSING THE REGION THIS MORNING WILL BRING SOME LIGHT PRECIP TO THE TAF SITES THROUGH 18Z. WITH SFC TEMPERATURES AOB FREEZING AT THE ONSET...COULD SEE SOME LIGHT WINTRY PCPN OF SN/PL/ZR FOR MAINLY KRIC AND KSBY. CEILINGS WILL STRUGGLE TO DROP BELOW 2500 FT DEW TO THE LOW LEVEL DRY AIR SO THE LIGHT PCPN WILL BE FALLING OUT OF SOME HIGHER DECKS AND VSBY WILL BE MAINLY ABOVE 5 MI. SFC TEMPS SHOULD CLIMB ABOVE FREEZING BETWEEN 15Z AND 17Z AS THE SOUTHERLY FLOW INCREASE TURNING ANY LINGER PCPN TO RAIN. FOR PHF/ORF/ECG...THE LOW LEVEL DRY AIR BETWEEN THE SFC AND 5K FT WILL INHIBIT MUCH OF THE PCPN FROM REACHING THE GROUND SO HAVE NOT INCLUDED ANY MENTION IN THE FORECAST AS OF YET AND SFC TEMPS SHOULD BE ABOVE FREEZING SHOULD ANY PCPN REACH THE GROUND. THE SHORTWAVE SHOULD BE EXITING THE AREA BY 18Z WITH THE CLOUDS BREAKING UP DURING THE AFTERNOON HOURS. FOR TONIGHT...MODELS SHOWING SOME LOW LEVEL MOISTURE MOVING NORTHEAST OUT OF THE CAROLINAS THAT COULD PRODUCE SOME MVFR STRATUS CONDITIONS. THE INCREASING SOUTHERLY FLOW ON TUESDAY INTO WEDNESDAY SHOULD PRODUCE VFR CONDITIONS. THE ARRIVAL OF A COLD FRONT LATER WEDNESDAY INTO THURSDAY COULD PRODUCE MVFR/IFR CONDITIONS ONCE AGAIN. && .MARINE... A WARM FRONT WILL LIFT NORTH OF THE REGION LATER THIS MORNING ALLOWING FOR INCREASING SW FLOW. BY THIS AFTERNOON...SW WINDS OF 15-20 KT ARE EXPECTED ON THE OCEAN AND ALSO THE CENTRAL CHES BAY NORTH OF WINDMILL PT AS THE LOW LEVEL PRESSURE GRADIENT TIGHTENS BETWEEN DEPARTING HIGH PRESSURE AND LOW PRESSURE OVER THE EASTERN GREAT LAKES. SOME GUSTS UP TO 25 KT ARE POSSIBLE NORTH OF CHINCOTEAGUE LATE TODAY...BUT HAVE CAPPED WIND GUSTS BELOW SCA THRESHOLDS ATTM AS CONFIDENCE NOT HIGH ENOUGH FOR AN SCA HEADLINE. HOWEVER...HAVE RAISED AN SCA FOR THE CENTRAL CHES BAY NORTH OF WINDMILL AS NEWEST HIGH-RES MODEL DATA INSISTS SW FLOW WILL INCREASE TO 15-20 KT THIS AFTERNOON/EVENING. SW WINDS GRADUALLY TAPER OFF LATE TONIGHT INTO EARLY TUESDAY. LIGHT S-SW FLOW IS ANTICIPATED ON TUESDAY. THE NEXT LOW PRESSURE SYSTEM AND ITS ASSOCIATED COLD FRONT WILL APPROACH THE REGION FROM THE WEST LATE WEDNESDAY. AHEAD OF THE FRONT...A STRONG LOW-LEVEL JET WILL DEVELOP OVER THE REGION AND THE WATERS. WHILE THE STRONGEST WINDS WILL REMAIN ALOFT...ENOUGH WIND SHOULD REACH THE WATER SFC TO WARRANT SCA CONDITIONS OVER ALL WATERS FROM MID-MORNING WED INTO EARLY THURS MORNING. SEAS RAPIDLY BUILD WED AFTERNOON...REACHING 8 TO 10 FT OUT AROUND 20 NM LATE. COLD FRONT EXPECTED TO CROSS THE WATERS EARLY THURS MORNING ACCOMPANIED BY MODEST CAA. UNSETTLED WEATHER WILL CONTINUE THROUGH THE WEEKEND AS A SERIES OF DISTURBANCES CROSS THE WATERS. ADDITIONAL SCA HEADLINES WILL LIKELY BE NEEDED THURSDAY AND FRIDAY...AND POSSIBLY INTO THE WEEKEND. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST TUESDAY FOR ANZ630. && $$ SYNOPSIS...ALB NEAR TERM...SAM SHORT TERM...ALB/MAM LONG TERM...SAM AVIATION...JDM MARINE...JDM
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
958 PM EST TUE JAN 29 2013 .SYNOPSIS... ISSUED AT 348 PM EST TUE JAN 29 2013 AREAS OF FOG WILL GIVE WAY TO HEAVY RAIN TONIGHT AS LOW PRESSURE MOVES THROUGH. SOME FLOODING IS POSSIBLE. THE RAIN WILL MOVE EAST ON WEDNESDAY WITH COLDER AIR MOVING IN ALONG WITH SOME RAIN CHANGING TO SNOW. TEMPERATURES WILL CONTINUE TO FALL THROUGH FRIDAY ALONG WITH LAKE EFFECT SNOW SHOWERS. && .UPDATE... ISSUED AT 817 PM EST TUE JAN 29 2013 AT 0105Z THE KGRR 88D SHOWS RAIN AND ISOLATED THUNDERSTORMS. NO SEVERE WX IS ANTICIPATED IN OUR AREA TONIGHT. LATEST HIGHER RESOLUTION GUIDANCE SUCH AS THE 12Z 4KM WRF NMM INDICATES WE WILL HAVE RAIN AND SCATTERED THUNDERSTORMS THROUGH THE OVERNIGHT PERIOD. RAIN COULD BE HEAVY AT TIMES. THEREFORE NO HEADLINE CHANGES ARE PLANNED/NECESSARY THIS EVENING AND THE FLOOD WATCH CONTINUES IN EFFECT THROUGH WEDNESDAY AFTERNOON. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 348 PM EST TUE JAN 29 2013 AREAS OF PATCHY DENSE FOG WILL CONTINUE THIS EVENING ACROSS THE NORTHERN ZONES UNTIL THE WARM FRONT LIFTS THROUGH. COVERAGE IS VARIABLE ENOUGH TO NOT GO WITH A DENSE FOG ADVISORY BUT WILL HAVE TO MONITOR OBS NEXT FEW HOURS. FLOOD WATCH CONTINUES TONIGHT FOR ALL ZONES. MOST IF NOT ALL OF THE SNOW IS GONE ACROSS THE CENTRAL AND SOUTHERN ZONES BUT SOME SNOWMELT CONTRIBUTION REMAINS UP NORTH WHERE QPF IS EXPECTED TO BE 1 TO 2 INCHES. 12Z MODEL GUIDANCE SHIFTED NORTH WITH THE AXIS OF HEAVIEST QPF ALTHOUGH THE HRRR HAS BEEN SHOWING THE MOST CONVECTIVE...AND HEAVIER...RAINS FURTHER SOUTH AND EAST. SEE HYDRO SECTION OF FORECAST FOR SPECIFICS ON RIVER FLOOD WARNINGS. EXPECT THE HEAVIEST RAINS TO MOVE INTO WESTERN ZONES THIS EVENING THEN MARCH STEADILY ACROSS THE FORECAST AREA OVERNIGHT...DEPARTING THE EASTERN ZONES WEDNESDAY MORNING. THE DEFORMATION RAIN/SNOW ZONE SHOULD BE REACHING THE NORTHWEST FORECAST AREA WEDNESDAY MORNING. WILL HAVE TO WATCH THIS AREA FOR ACCUMULATING SNOW BY LATE WEDNESDAY MORNING INTO THE AFTERNOON. COLD AIR ARRIVES IN THE AFTERNOON WITH LAKE EFFECT KICKING IN WEDNESDAY NIGHT. EXPECT LAKE EFFECT TO PENETRATE INLAND THURSDAY AND THURSDAY NIGHT WITH FLOW GOING NORTHWEST TO WEST. .LONG TERM...(FRIDAY THROUGH TUESDAY) ISSUED AT 348 PM EST TUE JAN 29 2013 THE ECMWF AND GFS ARE IN PRETTY GOOD AGREEMENT THROUGH THE WEEKEND. BOTH MODELS SHOW THE DEEP UPPER TROUGH MOVING EAST AWAY FROM THE AREA AND TAKING THE CORE OF THE COLD AIR WITH IT. THE DGZ IS ALREADY GOING TO BE VERY LOW FRIDAY AND WITH THE COLD AIR MOVING AWAY WE/LL SEE THE EASTERN EDGE OF THE LAKE EFFECT SNOW SHOWERS RETREATING TOWARD THE LAKE SHORE AND THEN DIMINISHING FRIDAY NIGHT AND SATURDAY. THE NEXT CHC FOR SNOW AFTER THAT WILL BE MONDAY WHEN A CLIPPER MOVES TOWARD NRN LWR. THE GFS TAKES A MORE SRN TRACK AND WOULD GIVE US MORE SNOW. HOWEVER...WE HAVE NOT HAD MANY CLIPPERS THAT HAVE CROSSED THE CWA THIS YEAR AND SO WE/LL LEAN MORE TOWARD THE FARTHER NORTH ECMWF. TEMPS WILL WARM FROM HIGHS IN THE MID TEENS FRIDAY TO MID 30S BY MONDAY BEFORE COOLING OFF TUESDAY AFTER THE CLIPPER DRAGS A COLD FRONT THROUGH. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 715 PM EST TUE JAN 29 2013 ACTIVE WEATHER EXPECTED THE NEXT 24 HOURS ACROSS THE TAF SITES WITH A COLD FRONT EXPECTED TO MOVE THROUGH THE AREA TONIGHT INTO WEDNESDAY MORNING. THUNDERSTORMS WILL LIKELY AFFECT THE TAF SITES BETWEEN 01Z AND 07Z ON THE LEADING EDGE OF A SHIELD OF PRECIPITATION. STEADIER MODERATE RAINS ARE EXPECTED OVERNIGHT. IFR AND MVFR CONDITIONS WILL BE COMMON THIS EVENING...TRENDING TOWARD MORE WIDESPREAD IFR LATER TONIGHT INTO WEDNESDAY MORNING. THE IFR CONDITIONS WILL LIFT BACK TO MVFR TOMORROW AFTERNOON AS THE COLD FRONT PRESSES EAST. SOME SNOW WILL BEGIN TO MIX BACK IN TOWARD KMKG DURING THE AFTERNOON AND TOWARD KGRR TOWARD EVENING. && .MARINE... ISSUED AT 348 PM EST TUE JAN 29 2013 WILL HOIST A SMALL CRAFT ADVISORY FOR TONIGHT THROUGH THURSDAY MORNING. THIS MAY HAVE TO BE UPGRADED TO A GALE WARNING FOR WEDNESDAY LATER ON...BUT FOR NOW IT APPEARED MARGINAL ENOUGH TO JUST GO WITH A SCA THROUGH THE PERIOD. && .HYDROLOGY... ISSUED AT 957 PM EST TUE JAN 29 2013 HAVE ISSUED A FLOOD WARNING FOR THE LAKESHORE COUNTIES AS WELL AS LAKE AND NEWAYGO COUNTY. AREAS THAT RECEIVED SUBSTANTIAL LAKE EFFECT SNOW IN THE LAST WEEK OR SO HAVE SEEN A RAPID SNOW MELT THAT HAS OCCURRED OVER FROZEN GROUND. THEREFORE...SNOW MELT WATER AND RAINFALL IS GOING INTO RUNOFF AS OPPOSED TO INFILTRATING INTO THE GROUND. RAINFALL TOTALS HAVE BEEN IMPRESSIVE SINCE LAST NIGHT...WITH MUSKEGON SEEING OVER 2.25 INCHES OF RAIN NOW. THE COMBINATION SNOW MELT WATER...RAINFALL OF THE LAST 24 HOURS AND ADDITIONAL RAINFALL COMING UP TONIGHT HAS PROMPTED THE AREAL FLOOD WARNING. DROPPED THE FLOOD WATCH IN THESE COUNTIES GIVEN THE WARNING. THE FLOOD WATCH CONTINUES FOR THE REMAINDER OF THE AREA. THE EXPECTATIONS IN THE WARNING AREA ARE THAT WE WILL SEE SMALLER STREAMS AND RIVERS SPILL OUR OF THERE BANKS...PONDING OF WATER IN LOW SPOTS OF ROADWAYS AND FLOODING OF CULVERTS...DITCHES AND FIELDS. A SATELLITE PRECIPITATION ESTIMATE (SPENES) WAS RECENTLY ISSUED ADVISING OF THE POTENTIAL OF ANOTHER 1-2 INCHES OF RAINFALL ACROSS OUR AREA THROUGH 400 AM. WE WILL BE MONITORING THE COUNTIES TO THE EAST OF THE WARNING AREA...BUT CONCERNS ARE NOT AS HIGH THERE AS THE SNOW PACK WAS MINIMAL. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...FLOOD WATCH THROUGH WEDNESDAY AFTERNOON FOR MIZ039-040-045-046- 051-052-057>059-065>067-072>074. LM...SMALL CRAFT ADVISORY FROM 1 AM WEDNESDAY TO 7 AM EST THURSDAY FOR LMZ844>849. && $$ UPDATE...LAURENS SYNOPSIS...OSTUNO SHORT TERM...OSTUNO LONG TERM...93 AVIATION...DUKE HYDROLOGY...DUKE MARINE...OSTUNO
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
818 PM EST TUE JAN 29 2013 .SYNOPSIS... ISSUED AT 348 PM EST TUE JAN 29 2013 AREAS OF FOG WILL GIVE WAY TO HEAVY RAIN TONIGHT AS LOW PRESSURE MOVES THROUGH. SOME FLOODING IS POSSIBLE. THE RAIN WILL MOVE EAST ON WEDNESDAY WITH COLDER AIR MOVING IN ALONG WITH SOME RAIN CHANGING TO SNOW. TEMPERATURES WILL CONTINUE TO FALL THROUGH FRIDAY ALONG WITH LAKE EFFECT SNOW SHOWERS. && .UPDATE... ISSUED AT 817 PM EST TUE JAN 29 2013 AT 0105Z THE KGRR 88D SHOWS RAIN AND ISOLATED THUNDERSTORMS. NO SEVERE WX IS ANTICIPATED IN OUR AREA TONIGHT. LATEST HIGHER RESOLUTION GUIDANCE SUCH AS THE 12Z 4KM WRF NMM INDICATES WE WILL HAVE RAIN AND SCATTERED THUNDERSTORMS THROUGH THE OVERNIGHT PERIOD. RAIN COULD BE HEAVY AT TIMES. THEREFORE NO HEADLINE CHANGES ARE PLANNED/NECESSARY THIS EVENING AND THE FLOOD WATCH CONTINUES IN EFFECT THROUGH WEDNESDAY AFTERNOON. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 348 PM EST TUE JAN 29 2013 AREAS OF PATCHY DENSE FOG WILL CONTINUE THIS EVENING ACROSS THE NORTHERN ZONES UNTIL THE WARM FRONT LIFTS THROUGH. COVERAGE IS VARIABLE ENOUGH TO NOT GO WITH A DENSE FOG ADVISORY BUT WILL HAVE TO MONITOR OBS NEXT FEW HOURS. FLOOD WATCH CONTINUES TONIGHT FOR ALL ZONES. MOST IF NOT ALL OF THE SNOW IS GONE ACROSS THE CENTRAL AND SOUTHERN ZONES BUT SOME SNOWMELT CONTRIBUTION REMAINS UP NORTH WHERE QPF IS EXPECTED TO BE 1 TO 2 INCHES. 12Z MODEL GUIDANCE SHIFTED NORTH WITH THE AXIS OF HEAVIEST QPF ALTHOUGH THE HRRR HAS BEEN SHOWING THE MOST CONVECTIVE...AND HEAVIER...RAINS FURTHER SOUTH AND EAST. SEE HYDRO SECTION OF FORECAST FOR SPECIFICS ON RIVER FLOOD WARNINGS. EXPECT THE HEAVIEST RAINS TO MOVE INTO WESTERN ZONES THIS EVENING THEN MARCH STEADILY ACROSS THE FORECAST AREA OVERNIGHT...DEPARTING THE EASTERN ZONES WEDNESDAY MORNING. THE DEFORMATION RAIN/SNOW ZONE SHOULD BE REACHING THE NORTHWEST FORECAST AREA WEDNESDAY MORNING. WILL HAVE TO WATCH THIS AREA FOR ACCUMULATING SNOW BY LATE WEDNESDAY MORNING INTO THE AFTERNOON. COLD AIR ARRIVES IN THE AFTERNOON WITH LAKE EFFECT KICKING IN WEDNESDAY NIGHT. EXPECT LAKE EFFECT TO PENETRATE INLAND THURSDAY AND THURSDAY NIGHT WITH FLOW GOING NORTHWEST TO WEST. .LONG TERM...(FRIDAY THROUGH TUESDAY) ISSUED AT 348 PM EST TUE JAN 29 2013 THE ECMWF AND GFS ARE IN PRETTY GOOD AGREEMENT THROUGH THE WEEKEND. BOTH MODELS SHOW THE DEEP UPPER TROUGH MOVING EAST AWAY FROM THE AREA AND TAKING THE CORE OF THE COLD AIR WITH IT. THE DGZ IS ALREADY GOING TO BE VERY LOW FRIDAY AND WITH THE COLD AIR MOVING AWAY WE/LL SEE THE EASTERN EDGE OF THE LAKE EFFECT SNOW SHOWERS RETREATING TOWARD THE LAKE SHORE AND THEN DIMINISHING FRIDAY NIGHT AND SATURDAY. THE NEXT CHC FOR SNOW AFTER THAT WILL BE MONDAY WHEN A CLIPPER MOVES TOWARD NRN LWR. THE GFS TAKES A MORE SRN TRACK AND WOULD GIVE US MORE SNOW. HOWEVER...WE HAVE NOT HAD MANY CLIPPERS THAT HAVE CROSSED THE CWA THIS YEAR AND SO WE/LL LEAN MORE TOWARD THE FARTHER NORTH ECMWF. TEMPS WILL WARM FROM HIGHS IN THE MID TEENS FRIDAY TO MID 30S BY MONDAY BEFORE COOLING OFF TUESDAY AFTER THE CLIPPER DRAGS A COLD FRONT THROUGH. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 715 PM EST TUE JAN 29 2013 ACTIVE WEATHER EXPECTED THE NEXT 24 HOURS ACROSS THE TAF SITES WITH A COLD FRONT EXPECTED TO MOVE THROUGH THE AREA TONIGHT INTO WEDNESDAY MORNING. THUNDERSTORMS WILL LIKELY AFFECT THE TAF SITES BETWEEN 01Z AND 07Z ON THE LEADING EDGE OF A SHIELD OF PRECIPITATION. STEADIER MODERATE RAINS ARE EXPECTED OVERNIGHT. IFR AND MVFR CONDITIONS WILL BE COMMON THIS EVENING...TRENDING TOWARD MORE WIDESPREAD IFR LATER TONIGHT INTO WEDNESDAY MORNING. THE IFR CONDITIONS WILL LIFT BACK TO MVFR TOMORROW AFTERNOON AS THE COLD FRONT PRESSES EAST. SOME SNOW WILL BEGIN TO MIX BACK IN TOWARD KMKG DURING THE AFTERNOON AND TOWARD KGRR TOWARD EVENING. && .MARINE... ISSUED AT 348 PM EST TUE JAN 29 2013 WILL HOIST A SMALL CRAFT ADVISORY FOR TONIGHT THROUGH THURSDAY MORNING. THIS MAY HAVE TO BE UPGRADED TO A GALE WARNING FOR WEDNESDAY LATER ON...BUT FOR NOW IT APPEARED MARGINAL ENOUGH TO JUST GO WITH A SCA THROUGH THE PERIOD. && .HYDROLOGY... ISSUED AT 348 PM EST TUE JAN 29 2013 SCOTTVILLE ON THE PERE MARQUETTE IS FORECAST TO FLOOD...BUT OTHER RIVER POINTS ARE CURRENTLY EXPECTED TO STAY BELOW FLOOD STAGE. WILL HAVE TO WATCH THE PROGRESSION OF RAIN AND SNOW MELT THIS EVENING AND SOME OTHER SITES MAY BE ADDED TO FLOOD WARNINGS AT SOME POINT TONIGHT. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...FLOOD WATCH THROUGH WEDNESDAY AFTERNOON FOR MIZ037>040-043>046- 050>052-056>059-064>067-071>074. LM...SMALL CRAFT ADVISORY FROM 1 AM WEDNESDAY TO 7 AM EST THURSDAY FOR LMZ844>849. && $$ UPDATE...LAURENS SYNOPSIS...OSTUNO SHORT TERM...OSTUNO LONG TERM...93 AVIATION...DUKE HYDROLOGY...OSTUNO MARINE...OSTUNO
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
715 PM EST TUE JAN 29 2013 .SYNOPSIS... ISSUED AT 348 PM EST TUE JAN 29 2013 AREAS OF FOG WILL GIVE WAY TO HEAVY RAIN TONIGHT AS LOW PRESSURE MOVES THROUGH. SOME FLOODING IS POSSIBLE. THE RAIN WILL MOVE EAST ON WEDNESDAY WITH COLDER AIR MOVING IN ALONG WITH SOME RAIN CHANGING TO SNOW. TEMPERATURES WILL CONTINUE TO FALL THROUGH FRIDAY ALONG WITH LAKE EFFECT SNOW SHOWERS. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 348 PM EST TUE JAN 29 2013 AREAS OF PATCHY DENSE FOG WILL CONTINUE THIS EVENING ACROSS THE NORTHERN ZONES UNTIL THE WARM FRONT LIFTS THROUGH. COVERAGE IS VARIABLE ENOUGH TO NOT GO WITH A DENSE FOG ADVISORY BUT WILL HAVE TO MONITOR OBS NEXT FEW HOURS. FLOOD WATCH CONTINUES TONIGHT FOR ALL ZONES. MOST IF NOT ALL OF THE SNOW IS GONE ACROSS THE CENTRAL AND SOUTHERN ZONES BUT SOME SNOWMELT CONTRIBUTION REMAINS UP NORTH WHERE QPF IS EXPECTED TO BE 1 TO 2 INCHES. 12Z MODEL GUIDANCE SHIFTED NORTH WITH THE AXIS OF HEAVIEST QPF ALTHOUGH THE HRRR HAS BEEN SHOWING THE MOST CONVECTIVE...AND HEAVIER...RAINS FURTHER SOUTH AND EAST. SEE HYDRO SECTION OF FORECAST FOR SPECIFICS ON RIVER FLOOD WARNINGS. EXPECT THE HEAVIEST RAINS TO MOVE INTO WESTERN ZONES THIS EVENING THEN MARCH STEADILY ACROSS THE FORECAST AREA OVERNIGHT...DEPARTING THE EASTERN ZONES WEDNESDAY MORNING. THE DEFORMATION RAIN/SNOW ZONE SHOULD BE REACHING THE NORTHWEST FORECAST AREA WEDNESDAY MORNING. WILL HAVE TO WATCH THIS AREA FOR ACCUMULATING SNOW BY LATE WEDNESDAY MORNING INTO THE AFTERNOON. COLD AIR ARRIVES IN THE AFTERNOON WITH LAKE EFFECT KICKING IN WEDNESDAY NIGHT. EXPECT LAKE EFFECT TO PENETRATE INLAND THURSDAY AND THURSDAY NIGHT WITH FLOW GOING NORTHWEST TO WEST. .LONG TERM...(FRIDAY THROUGH TUESDAY) ISSUED AT 348 PM EST TUE JAN 29 2013 THE ECMWF AND GFS ARE IN PRETTY GOOD AGREEMENT THROUGH THE WEEKEND. BOTH MODELS SHOW THE DEEP UPPER TROUGH MOVING EAST AWAY FROM THE AREA AND TAKING THE CORE OF THE COLD AIR WITH IT. THE DGZ IS ALREADY GOING TO BE VERY LOW FRIDAY AND WITH THE COLD AIR MOVING AWAY WE/LL SEE THE EASTERN EDGE OF THE LAKE EFFECT SNOW SHOWERS RETREATING TOWARD THE LAKE SHORE AND THEN DIMINISHING FRIDAY NIGHT AND SATURDAY. THE NEXT CHC FOR SNOW AFTER THAT WILL BE MONDAY WHEN A CLIPPER MOVES TOWARD NRN LWR. THE GFS TAKES A MORE SRN TRACK AND WOULD GIVE US MORE SNOW. HOWEVER...WE HAVE NOT HAD MANY CLIPPERS THAT HAVE CROSSED THE CWA THIS YEAR AND SO WE/LL LEAN MORE TOWARD THE FARTHER NORTH ECMWF. TEMPS WILL WARM FROM HIGHS IN THE MID TEENS FRIDAY TO MID 30S BY MONDAY BEFORE COOLING OFF TUESDAY AFTER THE CLIPPER DRAGS A COLD FRONT THROUGH. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 715 PM EST TUE JAN 29 2013 ACTIVE WEATHER EXPECTED THE NEXT 24 HOURS ACROSS THE TAF SITES WITH A COLD FRONT EXPECTED TO MOVE THROUGH THE AREA TONIGHT INTO WEDNESDAY MORNING. THUNDERSTORMS WILL LIKELY AFFECT THE TAF SITES BETWEEN 01Z AND 07Z ON THE LEADING EDGE OF A SHIELD OF PRECIPITATION. STEADIER MODERATE RAINS ARE EXPECTED OVERNIGHT. IFR AND MVFR CONDITIONS WILL BE COMMON THIS EVENING...TRENDING TOWARD MORE WIDESPREAD IFR LATER TONIGHT INTO WEDNESDAY MORNING. THE IFR CONDITIONS WILL LIFT BACK TO MVFR TOMORROW AFTERNOON AS THE COLD FRONT PRESSES EAST. SOME SNOW WILL BEGIN TO MIX BACK IN TOWARD KMKG DURING THE AFTERNOON AND TOWARD KGRR TOWARD EVENING. && .MARINE... ISSUED AT 348 PM EST TUE JAN 29 2013 WILL HOIST A SMALL CRAFT ADVISORY FOR TONIGHT THROUGH THURSDAY MORNING. THIS MAY HAVE TO BE UPGRADED TO A GALE WARNING FOR WEDNESDAY LATER ON...BUT FOR NOW IT APPEARED MARGINAL ENOUGH TO JUST GO WITH A SCA THROUGH THE PERIOD. && .HYDROLOGY... ISSUED AT 348 PM EST TUE JAN 29 2013 SCOTTVILLE ON THE PERE MARQUETTE IS FORECAST TO FLOOD...BUT OTHER RIVER POINTS ARE CURRENTLY EXPECTED TO STAY BELOW FLOOD STAGE. WILL HAVE TO WATCH THE PROGRESSION OF RAIN AND SNOW MELT THIS EVENING AND SOME OTHER SITES MAY BE ADDED TO FLOOD WARNINGS AT SOME POINT TONIGHT. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...FLOOD WATCH THROUGH WEDNESDAY AFTERNOON FOR MIZ037>040-043>046- 050>052-056>059-064>067-071>074. LM...SMALL CRAFT ADVISORY FROM 1 AM WEDNESDAY TO 7 AM EST THURSDAY FOR LMZ844>849. && $$ UPDATE...93 SYNOPSIS...OSTUNO SHORT TERM...OSTUNO LONG TERM...93 AVIATION...DUKE HYDROLOGY...OSTUNO MARINE...OSTUNO
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
607 PM EST TUE JAN 29 2013 .SYNOPSIS... ISSUED AT 348 PM EST TUE JAN 29 2013 AREAS OF FOG WILL GIVE WAY TO HEAVY RAIN TONIGHT AS LOW PRESSURE MOVES THROUGH. SOME FLOODING IS POSSIBLE. THE RAIN WILL MOVE EAST ON WEDNESDAY WITH COLDER AIR MOVING IN ALONG WITH SOME RAIN CHANGING TO SNOW. TEMPERATURES WILL CONTINUE TO FALL THROUGH FRIDAY ALONG WITH LAKE EFFECT SNOW SHOWERS. && .UPDATE... ISSUED AT 606 PM EST TUE JAN 29 2013 SENDING OUT A QUICK UPDATE TO ADD THUNDER TO GRIDS THIS EVENING. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 348 PM EST TUE JAN 29 2013 AREAS OF PATCHY DENSE FOG WILL CONTINUE THIS EVENING ACROSS THE NORTHERN ZONES UNTIL THE WARM FRONT LIFTS THROUGH. COVERAGE IS VARIABLE ENOUGH TO NOT GO WITH A DENSE FOG ADVISORY BUT WILL HAVE TO MONITOR OBS NEXT FEW HOURS. FLOOD WATCH CONTINUES TONIGHT FOR ALL ZONES. MOST IF NOT ALL OF THE SNOW IS GONE ACROSS THE CENTRAL AND SOUTHERN ZONES BUT SOME SNOWMELT CONTRIBUTION REMAINS UP NORTH WHERE QPF IS EXPECTED TO BE 1 TO 2 INCHES. 12Z MODEL GUIDANCE SHIFTED NORTH WITH THE AXIS OF HEAVIEST QPF ALTHOUGH THE HRRR HAS BEEN SHOWING THE MOST CONVECTIVE...AND HEAVIER...RAINS FURTHER SOUTH AND EAST. SEE HYDRO SECTION OF FORECAST FOR SPECIFICS ON RIVER FLOOD WARNINGS. EXPECT THE HEAVIEST RAINS TO MOVE INTO WESTERN ZONES THIS EVENING THEN MARCH STEADILY ACROSS THE FORECAST AREA OVERNIGHT...DEPARTING THE EASTERN ZONES WEDNESDAY MORNING. THE DEFORMATION RAIN/SNOW ZONE SHOULD BE REACHING THE NORTHWEST FORECAST AREA WEDNESDAY MORNING. WILL HAVE TO WATCH THIS AREA FOR ACCUMULATING SNOW BY LATE WEDNESDAY MORNING INTO THE AFTERNOON. COLD AIR ARRIVES IN THE AFTERNOON WITH LAKE EFFECT KICKING IN WEDNESDAY NIGHT. EXPECT LAKE EFFECT TO PENETRATE INLAND THURSDAY AND THURSDAY NIGHT WITH FLOW GOING NORTHWEST TO WEST. .LONG TERM...(FRIDAY THROUGH TUESDAY) ISSUED AT 348 PM EST TUE JAN 29 2013 THE ECMWF AND GFS ARE IN PRETTY GOOD AGREEMENT THROUGH THE WEEKEND. BOTH MODELS SHOW THE DEEP UPPER TROUGH MOVING EAST AWAY FROM THE AREA AND TAKING THE CORE OF THE COLD AIR WITH IT. THE DGZ IS ALREADY GOING TO BE VERY LOW FRIDAY AND WITH THE COLD AIR MOVING AWAY WE/LL SEE THE EASTERN EDGE OF THE LAKE EFFECT SNOW SHOWERS RETREATING TOWARD THE LAKE SHORE AND THEN DIMINISHING FRIDAY NIGHT AND SATURDAY. THE NEXT CHC FOR SNOW AFTER THAT WILL BE MONDAY WHEN A CLIPPER MOVES TOWARD NRN LWR. THE GFS TAKES A MORE SRN TRACK AND WOULD GIVE US MORE SNOW. HOWEVER...WE HAVE NOT HAD MANY CLIPPERS THAT HAVE CROSSED THE CWA THIS YEAR AND SO WE/LL LEAN MORE TOWARD THE FARTHER NORTH ECMWF. TEMPS WILL WARM FROM HIGHS IN THE MID TEENS FRIDAY TO MID 30S BY MONDAY BEFORE COOLING OFF TUESDAY AFTER THE CLIPPER DRAGS A COLD FRONT THROUGH. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1252 PM EST TUE JAN 29 2013 WIDESPREAD IFR/LIFR CONDITIONS EXPECTED THROUGH THE PERIOD. WE/LL SEE CONSIDERABLE RAIN TONIGHT AHEAD OF THE ARCTIC FRONT. TSRA ALSO EXPECTED FROM AROUND SUNSET THROUGH MUCH OF THE OVERNIGHT HOURS. IT/S POSSIBLE THAT SNOW WILL MIX IN WITH THE RAIN AT KMKG MID TO LATE MORNING WEDNESDAY. && .MARINE... ISSUED AT 348 PM EST TUE JAN 29 2013 WILL HOIST A SMALL CRAFT ADVISORY FOR TONIGHT THROUGH THURSDAY MORNING. THIS MAY HAVE TO BE UPGRADED TO A GALE WARNING FOR WEDNESDAY LATER ON...BUT FOR NOW IT APPEARED MARGINAL ENOUGH TO JUST GO WITH A SCA THROUGH THE PERIOD. && .HYDROLOGY... ISSUED AT 348 PM EST TUE JAN 29 2013 SCOTTVILLE ON THE PERE MARQUETTE IS FORECAST TO FLOOD...BUT OTHER RIVER POINTS ARE CURRENTLY EXPECTED TO STAY BELOW FLOOD STAGE. WILL HAVE TO WATCH THE PROGRESSION OF RAIN AND SNOW MELT THIS EVENING AND SOME OTHER SITES MAY BE ADDED TO FLOOD WARNINGS AT SOME POINT TONIGHT. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...FLOOD WATCH THROUGH WEDNESDAY AFTERNOON FOR MIZ037>040-043>046- 050>052-056>059-064>067-071>074. LM...SMALL CRAFT ADVISORY FROM 1 AM WEDNESDAY TO 7 AM EST THURSDAY FOR LMZ844>849. && $$ UPDATE...93 SYNOPSIS...OSTUNO SHORT TERM...OSTUNO LONG TERM...93 AVIATION...93 HYDROLOGY...OSTUNO MARINE...OSTUNO
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
413 PM CST MON JAN 28 2013 .DISCUSSION... FIRST THE HEADLINES. STARTING WITH THE HRRR/RUC THEN THE REST OF THE 12Z RUNS...MODELS BEGAN TO SHIFT HEAVY SNOW BAND FOR TONIGHT FARTHER NORTHWEST...KEEPING THE BULK OF THE SNOW NW OF THE MPX CWA. MAY STILL GET A COUPLE INCHES OF SNOW IN THE FAR NW CORNERS OF TODD...DOUGLAS...AND STEVENS COUNTIES...SO WITH THAT ALONG WITH MATCHING UP WITH WHAT NEIGHBORS WERE DOING...ISSUED A WINTER WEATHER ADVISORY FOR THOSE THREE COUNTIES. AT THE OTHER END OF THE CWA HAVE A FREEZING RAIN ADVISORY FOR NE 3 COUNTIES IN WI. NOT THRILLED WITH DOING THIS ADVISORY...BUT TO MATCH UP WITH NEIGHBORING OFFICES...INCLUDED THESE COUNTIES IN A FREEZING RAIN ADVY. EVERYWHERE ELSE...DENSE FOG IS LOOKING LIKE ALL BUT A CERTAINTY FOR TONIGHT...SO A NEW DENSE FOG ADVISORY HAS BEEN HOISTED. UPPER WAVE RESPONSIBLE FOR ALL OF THIS HEADLINE FUN IS A DEEP THROUGH THAT CAN BE SEEN ACROSS THE ERN ROCKIES THIS AFTERNOON...AND WILL SLIDE ACROSS THE CENTER OF THE CONUS THROUGH WEDNESDAY. AT THIS SFC...A 996 MB LOW AT 3 PM WAS CENTERED OVER ERN CO. FAIRLY GOOD CONSENSUS AMONGST GUIDANCE ON THIS LOW MOVING TO NEAR THE SE TIP OF MN BY TUESDAY MORNING...THEN OFF TO ERN LAKE SUPERIOR BY THE TUE AFTERNOON. SEEING AN IMPRESSIVE WARM FRONT MOVING NORTH ACROSS THE PLAINS WITH THIS LOW...WITH TEMPS IN THE LOWER 70S AND DEWPS IN THE LOWER 50S UP TO ALMOST THE IA BORDER. FOR THE WEATHER TONIGHT...LEANED MOST TOWARD THE 12Z NAM FOR TIMING PRECIP IN AND ACROSS THE AREA AS THIS IS A GOOD CONTINUATION OF WHAT THE RAP HAS BEEN SHOWING. RIGHT NOW...SEEING IMPRESSIVE FGEN BAND SETTING UP ACROSS NE SODAK INTO NW MN...AND LOOKING AT RAP H7-H6 FGEN FORECAST...SHOULD SEE AN INTENSE BAND OF SNOW SET UP FROM NEAR ABERDEEN UP TO DETROIT LAKES. WITHIN THE CENTER OF THE BAND SHOULD SEE A GOOD 4 TO 6 INCHES OF SNOW. FOR THE MPX AREA...FAR NW CORNERS OF OUR FAR NW COUNTIES SHOULD GET IN ON THE SRN FRINGE OF THIS BAND...WITH A COUPLE OF INCHES OF SNOW BEING POSSIBLE. FOR SNOW POTENTIAL IN THE WEST...WILL HAVE TO WHAT HAPPENS WITH A SECONDARY SHORT WAVE THAT SNEAKS UP WEST OF THE SFC LOW LATE TONIGHT INTO TUESDAY MORNING. THE GEM WAS THE MOST BULLISH WITH THIS WAVE...BRING A QUICK 2-3 INCHES OF SNOW TO WRN MN. DID NOT PUT MUCH STOCK IN IT...BUT NOTICING THAT TOWARD THE END OF RECENT RAP RUNS IT HAS BEEN SHOWING THIS SECONDARY BAND SNEAKING IN AS WELL...SO WILL NEED TO WATCH THIS OVERNIGHT TO SEE IF THE WINTER WEATHER ADVISORY NEEDS TO BE PULLED SOUTH. OUTSIDE OF THE NW CWA...SOUNDINGS SHOW WHATEVER HAPPENING TONIGHT TO BE DRIZZLE OR LIGHT RAIN...WITH ATMO ABOVE ABOUT H8 BEING DRY... AND LITTLE OR NO SATURATION BEING SEEN IN THE DENDRITIC GROWTH ZONE. SHOULD SEE DZ/RA RAPIDLY SPREAD NORTH AFTER 00Z AS STRONG LOW LEVEL THETA-E ADVECTION WORKS IN. AT THE NOSE OF THE LLJ...THE RAP IS EVEN INDICATING SOME THUNDER BEING POSSIBLE IN THE EAU AREA AROUND MIDNIGHT AS BEST LIS DROP TO AROUND -1. 18Z HRRR REFLECTIVITY FORECAST LOOKS CONVECTIVE IN THIS AREA AS WELL. OF COURSE WITH ALL OF THIS PRECIP THE KEY WILL BE SFC TEMPS. THE ENTIRE CWA CURRENTLY SITS BETWEEN 32 AND 36 AND WITH CONTINUED SOUTHEAST FLOW THROUGH THE NIGHT...DO NOT EXPECT THESE TO CHANGE MUCH...IN FACT...TEMPERATURES MAY CONTINUE TO RISE RIGHT THROUGH THE NIGHT ACROSS THE SE CWA. BECAUSE OF THESE MILD TEMPERATURES...WAS NOT TOO INCLINED TO ISSUE A FREEZING RAIN ADVY WITH IT BEING QUESTIONABLE IF TEMPS FALL BELOW FREEZING. IN ADDITION...WITH P-TYPE MAINLY BEING DZ...NOT EXPECTING MANY IMPACTS WITH DZ AND TEMPS IN THE 30S WITH ALREADY WET SFCS IN PLACE DUE TO MELTING TODAY. MAKE IT DRY WITH TEMPS IN THE 20S...AND IT WOULD BE A DIFFERENT STORY...BUT THAT IS NOT WHAT WE ARE DEALING WITH. WHERE THE HIGHEST POTENTIAL FOR MEANINGFUL FZRA EXISTS WOULD BE IN THE FAR NE CWA...WHERE THERE WILL BE THE POTENTIAL FOR RAIN THIS EVENING ON THE NOSE OF THE LLJ. AS FOR THE FOG...THERE IS NOTHING BUT A SEA OF DENSE FOG FROM SRN MN DOWN ACROSS IA AND ERN NEB. THIS WILL ADVECT RIGHT BACK NORTH THIS EVENING...WITH WIDESPREAD FOG EXPECTED AGAIN...AS SEEN WITH THE GRIDDED LAMP...HRRR...AND WRF-NMM. FOG SHOULD IMPROVE LATE TONIGHT FROM WEST TO EAST AS AN INVERTED TROUGH/COLD FRONT WORKS ACROSS MN. FOR SIMPLICITY SAKE...RAN THE FOG ADVY THROUGH 10 AM TUESDAY MORNING EVERYWHERE...BUT CONDITIONS SHOULD IMPROVE EARLIER THAN THAT IN WRN MN. PRECIPITATION SHOULD MOSTLY COME TO AN END BY TUESDAY AFTERNOON ACROSS THE AREA AS DRY ARCTIC HIGH BEGINS BUILDING IN. STILL SOME DISAGREEMENT WITH PRECIP POTENTIAL TUESDAY NIGHT AS ANOTHER SFC LOW RIPPLES NORTH ALONG THE FRONT FROM THE TULSA AREA UP TO MID MICHIGAN. HUNG SOME CHANCE POPS BACK ACROSS ERN AREA TO ACCOUNT FOR THE OFF CHANCE THAT SOME SNOW DEVELOPS WEST OF THE LOW. NOT ALL THAT EXCITED ABOUT SNOW POTENTIAL ON THE BACK SIDE OF THIS SYSTEM TUESDAY NIGHT INTO WEDNESDAY DUE TO THE FACT THAT UPPER FLOW WILL BE NEARLY PARALLEL TO THE FRONTAL BOUNDARY. THIS WILL LIKELY KEEP A COLD CONVEYOR BELT FROM DEVELOPING TO THE NORTH AND NORTHWEST OF THE LOW AS IT WORKS UP ALONG THE FRONT...WITH MOST ACTIVITY STAYING NEAR THE FRONT...AND NOT WORKING BACK TOWARD THE EAU AREA. OF COURSE THE BIG STORY FOR WEDNESDAY THROUGH FRIDAY WILL BE THE ARRIVAL OF ANOTHER SIGNIFICANT CHUNK OF ARCTIC AIR. TEMPERATURES WILL BE NEARLY STEADY OR FALLING MUCH OF WEDNESDAY AFTERNOON...AND BY WEDNESDAY NIGHT...THE COMBO OF TEMPS FALLING TO BELOW ZERO ON 15 TO 25 MPH NW WINDS WILL BRING BACK THE NEED FOR WIND CHILL ADVISORIES FROM WEDNESDAY NIGHT RIGHT INTO FRIDAY MORNING. AFTER FRIDAY...TEMPERATURES WILL MODERATE BACK CLOSER TO AND EVEN A LITTLE ABOVE NORMAL BY THE END OF THE WEEKEND. STILL SEEING THE POTENTIAL FOR A CLIPPER FRI NIGHT/SATURDAY ON THE ECMWF/GEM...WITH A COUPLE OF INCHES OF SNOW BEING POSSIBLE ALONG AND NORTH OF I-94. && .AVIATION... /18Z TAF ISSUANCE/ STRATUS AND FOG WILL CONTINUE THROUGH MOST OF THE PERIOD. WILL MAINTAIN IFR CONDITIONS THROUGH 18Z TUE. MAY SEE CONDITIONS IMPROVES TO MVFR TUE AFTERNOON AS SURFACE LOW PULLS EAST AND COLDER AIR MOVES IN. STILL LOOKS LIKE A PERIOD OF MIXED FREEZING RAIN/RAIN CHANGING TO SNOW OVER THE AREA OVERNIGHT. BEST FORCING REMAINS OVER NORTHWEST AREAS AND WILL CONTINUE TO MENTION FREEZING RAIN THIS EVENING TRANSITIONING TO SNOW AFTER 04Z AT KAXN. REMAINDER OF THE AREA WILL LIKELY SEE -FZDZ OR PLAIN -DZ AS SOUNDINGS NOT SHOWING A REAL DEEP MOIST LAYER...GENERALLY LESS THAN 6K FEET. DEEPER MOISTURE MAY WORK OVER THE FAR EASTERN AREAS LATER TONIGHT AS THE SURFACE LOW DEVELOPS TO THE SOUTHEAST. SURFACE WINDS BECOMING MORE SOUTHEAST IN THE WAKE OF THE SURFACE HIGH AND AHEAD OF FRONT OVER THE EASTERN DAKOTAS. SHOULD GRADUALLY TURN MORE NORTH/NORTHWEST WITH FROPA DURING THE PERIOD. WILL LIKELY INCREASE TO 10-15 KNOTS BY LATE TUESDAY MORNING OVER WESTERN AREAS. /OUTLOOK FOR KMSP/ TUE NGT...MVFR CIGS WITH FLURRIES. NW WIND 10-15 KTS. WED...MVFR CIGS WITH FLURRIES. NW WIND 15 TO 25 KTS. THU...MVFR CIGS WITH FLURRIES. NW WIND 10 TO 15 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...DENSE FOG ADVISORY UNTIL 9 AM CST TUESDAY FOR ANOKA-BENTON-BLUE EARTH-BROWN-CARVER-CHIPPEWA-CHISAGO-DAKOTA-FARIBAULT- FREEBORN-GOODHUE-HENNEPIN-ISANTI-KANABEC-KANDIYOHI-LAC QUI PARLE-LE SUEUR-MARTIN-MCLEOD-MEEKER-MILLE LACS-MORRISON- NICOLLET-POPE-RAMSEY-REDWOOD-RENVILLE-RICE-SCOTT-SHERBURNE- SIBLEY-STEARNS-STEELE-SWIFT-WASECA-WASHINGTON-WATONWAN- WRIGHT-YELLOW MEDICINE. WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR DOUGLAS- STEVENS-TODD. WI...DENSE FOG ADVISORY UNTIL 9 AM CST TUESDAY FOR DUNN-EAU CLAIRE- PEPIN-PIERCE-POLK-ST. CROIX. FREEZING RAIN ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM CST TUESDAY FOR BARRON-CHIPPEWA-RUSK. && $$ MPG/DWE
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
206 AM CST MON JAN 28 2013 .UPDATE... CANCELLED THE WINTER WX ADVISORY ACROSS WEST CENTRAL THROUGH SOUTH CENTRAL MN AND REPLACED IT WITH A DENSE FOG ADVISORY. MAY HAVE TO INCLUDE MORE OF THE CWA IF CONDITIONS WORSEN IN THE WAKE OF THE LIGHT PRECIPITATION. && .DISCUSSION... /ISSUED 413 PM CST SUN JAN 27 2013 QUITE THE INTERESTING SYSTEM UNFOLDING ACROSS THE AREA TODAY WITH INTENSE BAND OF SNOW WORKING ACROSS THE AREA THIS AFTERNOON WITHIN A STRONG ZONE OF FGEN IN THE H7-H6 LAYER. AS THIS STRONGER AND MORE PERSISTENT LIFT MOVED NORTH...THE AS ADVERTISED COLLAPSING OF THE WARM NOSE BACK BELOW FREEZING ALLOWED THE EARLY INITIAL PUSH OF FZRA/PL TO QUICKLY TRANSITION TO SNOW...AND QUITE THE IMPRESSIVE SNOW IT HAS BEEN. WITHIN THE MAIN BAND OF SNOW...RATES OF 1-2 INCHES PER HOUR HAVE BEEN QUITE COMMON. HERE AT THE OFFICE IN CHANHASSEN...WE GOT ABOUT 2.5 INCHES OF BETWEEN ABOUT 130 AND 330. THAT WOULD BE MORE SNOW IN 2 HOURS THAN WE HAVE SEEN IN THE REST OF THE MONTH COMBINED! THIS BAND OF SNOW WILL BE QUICKLY MOVING EAST WITH THE FGEN...WITH THE RAP SHOWING THE HEAVY SNOW SHOULD BE ALL BUT DONE IN THE TWIN CITIES BY 00Z...WITH IT NOT LASTING MUCH PAST 3Z IN THE LADYSMITH AREA. CURRENT GRIDS MAY NOT BE FAST ENOUGH IN CLEARING PRECIP OUT THIS EVENING...BUT THAT CAN BE UPDATED THROUGH THE EVENING. WHAT WILL BE TRICKY THOUGH...IS THAT AS THE MAIN PRECIP BATCH MOVES THROUGH...HAVE SEEN EXTENSIVE DZ/FG REPORTS ACROSS ERN NEB AND IA THAT WILL BE MOVING UP HERE THIS EVENING AND DO EXPECT A 2-4 HR WINDOW OF FZDZ BEHIND THE MAIN PRECIP BEFORE WE ARE LEFT WITH WHAT LOOKS TO BE A RATHER FOGGY NIGHT...WITH A DENSE FOG ADVY POSSIBLY IN THE BOOKS...THOUGH WILL WAIT UNTIL WINTER WEATHER HEADLINES ARE PULLED DOWN BEFORE ISSUING ANY DENSE FOG ADVISORIES. AS FOR THOSE WINTER WEATHER HEADLINES...ONLY CHANGE WAS TO TRIM A FEW COUNTIES OFF THE ADVY ON THE NW END WHERE PRECIP FAILED TO REACH AND MNDOT CONTINUES TO ADVERTISE GOOD TRAVEL CONDITIONS. DOUBT WE WILL HIT WINTER STORM WARNING CRITERIA FOR ANY ONE SPECIFIC TYPE OF PRECIPITATION /0.25 INCH OF FZRA AND 6 INCHES OF SNOW/...BUT THE COMBO OF A TENTH OF AN INCH OF FZRA BEING TOPPED WITH 3 TO 5 INCHES OF SNOW WARRANTS KEEPING THE WARNING GOING...THOUGH WOULD SUSPECT IT CAN BE PULLED BEFORE 6Z. WILL GET A BREAK IN THE PRECIP MOST OF THE DAY MONDAY...BEFORE THE MAIN TROUGH CURRENTLY ACROSS THE ROCKIES BEGINS PROGRESSING ACROSS THE PLAINS. WHAT WILL MAKE THIS PRECIP EVENT DIFFICULT FROM THE P-TYPE PERSPECTIVE IS THAT AS TODAYS PRECIP MOVES OUT...THE WARM NOSE WILL MOVE BACK IN...WITH ANOTHER MELTING LAYER IN PLACE MONDAY AFTERNOON AS THIS NEXT SYSTEM MOVES IN. MAIN SFC LOW IS FORECAST TO GO FROM NW KS MONDAY AFTERNOON TO THE U.P. OF MICH BY TUESDAY AFTERNOON. ALL MODELS SHOWING TWO BATCHES OF PRECIP WITH THIS SYSTEM. LLJ WARM SECTOR PRECIP LOOKS TO STAY WELL SE OF THE AREA...WHILE ANOTHER INTENSE BAND OF FGEN INDUCED SNOW MOVES ACROSS WRN INTO NE MN. WITH THIS SIGNAL...UPPED POPS TO THE CATEGORICAL RANGE IN THE NW CWA MONDAY NIGHT...WITH 2-3 INCHES OF SNOW UP IN THE MORRIS/ALEX AREA. CONFIDENCE ON PRECIP OCCURRENCE ACROSS THE REST OF THE AREA IS A BIT LOWER AS THESE TWO BATCHES OF PRECIP SPLIT THE AREA...BUT WHATEVER HAPPENS MONDAY NIGHT WITH PRECIP IN THE ERN 2/3RDS OF THE CWA...FORECAST SOUNDINGS AGAIN SAY THE P-TYPE WILL BE RA OR FZRA DEPENDING ON THE SFC TEMP. AFTER NEARLY STEADY TEMPERATURES TODAY THROUGH TUESDAY...THE ENCROACHMENT OF ANOTHER ARCTIC HIGH FOR THE END OF THE WEEK WILL LEAD TO A SIGNIFICANT COOL DOWN STARTING TUESDAY NIGHT. WILL SEE STRONG CAA ALL DAY WEDNESDAY RIGHT THROUGH WEDNESDAY NIGHT AS HIGH PRESSURE GOES FROM THE DAKOTAS OVER TO THE KANSAS CITY AREA BY FRIDAY MORNING. WILL SEE ANOTHER HEALTHY SURGE OF COLD BEHIND THIS SYSTEM...WITH H85 TEMPS BY THURSDAY AGAIN BACK BETWEEN 25 C AND 30 C BELOW ZERO. THIS WILL GIVE MUCH OF THE MN CWA ANOTHER SHOT AT SEEING SUB ZERO HIGHS THURSDAY AFTERNOON. FOR FRIDAY THROUGH THE WEEKEND...A MODERATION IN TEMPERATURES IS EXPECTED AS A CLIPPER SLIDES ACROSS NRN MN AND WI FRI NIGHT/SATURDAY. MAY SEE A QUICK 1-2 INCHES OF SNOW OUT OF THIS WITH CURRENT INDICATIONS BEING THAT THE BEST CHANCE FOR ACCUMULATING SNOW WILL BE NORTH OF I-94. && .AVIATION... /06Z TAF ISSUANCE/ NOT MUCH PRECIP REMAINING...BUT FOG WILL BE A CONCERN COME MORNING AT MOST OF THE TAF SITES...ESPECIALLY THOSE IN MN. DENSE FOG WITH 1/4SM OR LESS HAS BEEN SLOWLY ADVECTING EASTWARD OUT OF THE DAKOTAS. KAXN/KRWF AND EVEN KSTC SHOULD SEE LIFR VIS BY SUNRISE...HAVE ALSO INCLUDED IFR FOG IN EASTERN MN AND WESTERN WI...BUT DIDN`T GO 1/4SM YET. WINTRY MIX CHANGING OVER TO SNOW EXPECTED TO FROM WEST TO EAST ACROSS AREA LATE THIS AFTERNOON INTO THE EVENING. REGARDLESS...SHOULD BE IFR ALL DAY AND NIGHT. KMSP... STILL POTENTIAL FOR 1/4SM DENSE FOG AT SOME POINT LATE IN THE MORNING...BUT PLAYED IT A LITTLE CONSERVATIVE AT THE AIRPORT FOR NOW. HOWEVER...HIGH CONFIDENCE IN IFR ALL DAY...BUT THERE SHOULDN`T BE ANY NEW PRECIP UNTIL THIS EVENING. PRECIP COULD ARRIVE AS EARLY AS THE LAST HALF OF THE EVENING COMMUTE...BUT MORE LIKELY WILL HOLD OFF UNTIL THE LATE EVENING AND COME IN AS A WINTRY MIX BEFORE CHANGING OVER TO SNOW LATE TONIGHT. /OUTLOOK FOR KMSP/ TUE...MVFR/IFR CONDITIONS IN THE MORNING...MVFR CIGS BY AFTERNOON. CHC -SN IN THE MORNING. NW WIND 5-10KT. WED...MVFR CIGS. NW WIND 15G25KT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR BLUE EARTH- BROWN-CHIPPEWA-FARIBAULT-FREEBORN-GOODHUE-KANDIYOHI-LAC QUI PARLE-LE SUEUR-MARTIN-MCLEOD-MEEKER-NICOLLET-POPE-REDWOOD- RENVILLE-RICE-SIBLEY-STEELE-STEVENS-SWIFT-WASECA-WATONWAN- YELLOW MEDICINE. WINTER WEATHER ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR ANOKA-BENTON-CARVER-CHISAGO-DAKOTA-DOUGLAS-HENNEPIN-ISANTI- KANABEC-MILLE LACS-MORRISON-RAMSEY-SCOTT-SHERBURNE-STEARNS- TODD-WASHINGTON-WRIGHT. WI...WINTER WEATHER ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR BARRON-CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX. && $$ RAH/MPG/CLF
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
1225 AM CST MON JAN 28 2013 .UPDATE... UPDATED FOR THE 06Z AVIATION DISCUSSION BELOW. .DISCUSSION... QUITE THE INTERESTING SYSTEM UNFOLDING ACROSS THE AREA TODAY WITH INTENSE BAND OF SNOW WORKING ACROSS THE AREA THIS AFTERNOON WITHIN A STRONG ZONE OF FGEN IN THE H7-H6 LAYER. AS THIS STRONGER AND MORE PERSISTENT LIFT MOVED NORTH...THE AS ADVERTISED COLLAPSING OF THE WARM NOSE BACK BELOW FREEZING ALLOWED THE EARLY INITIAL PUSH OF FZRA/PL TO QUICKLY TRANSITION TO SNOW...AND QUITE THE IMPRESSIVE SNOW IT HAS BEEN. WITHIN THE MAIN BAND OF SNOW...RATES OF 1-2 INCHES PER HOUR HAVE BEEN QUITE COMMON. HERE AT THE OFFICE IN CHANHASSEN...WE GOT ABOUT 2.5 INCHES OF BETWEEN ABOUT 130 AND 330. THAT WOULD BE MORE SNOW IN 2 HOURS THAN WE HAVE SEEN IN THE REST OF THE MONTH COMBINED! THIS BAND OF SNOW WILL BE QUICKLY MOVING EAST WITH THE FGEN...WITH THE RAP SHOWING THE HEAVY SNOW SHOULD BE ALL BUT DONE IN THE TWIN CITIES BY 00Z...WITH IT NOT LASTING MUCH PAST 3Z IN THE LADYSMITH AREA. CURRENT GRIDS MAY NOT BE FAST ENOUGH IN CLEARING PRECIP OUT THIS EVENING...BUT THAT CAN BE UPDATED THROUGH THE EVENING. WHAT WILL BE TRICKY THOUGH...IS THAT AS THE MAIN PRECIP BATCH MOVES THROUGH...HAVE SEEN EXTENSIVE DZ/FG REPORTS ACROSS ERN NEB AND IA THAT WILL BE MOVING UP HERE THIS EVENING AND DO EXPECT A 2-4 HR WINDOW OF FZDZ BEHIND THE MAIN PRECIP BEFORE WE ARE LEFT WITH WHAT LOOKS TO BE A RATHER FOGGY NIGHT...WITH A DENSE FOG ADVY POSSIBLY IN THE BOOKS...THOUGH WILL WAIT UNTIL WINTER WEATHER HEADLINES ARE PULLED DOWN BEFORE ISSUING ANY DENSE FOG ADVISORIES. AS FOR THOSE WINTER WEATHER HEADLINES...ONLY CHANGE WAS TO TRIM A FEW COUNTIES OFF THE ADVY ON THE NW END WHERE PRECIP FAILED TO REACH AND MNDOT CONTINUES TO ADVERTISE GOOD TRAVEL CONDITIONS. DOUBT WE WILL HIT WINTER STORM WARNING CRITERIA FOR ANY ONE SPECIFIC TYPE OF PRECIPITATION /0.25 INCH OF FZRA AND 6 INCHES OF SNOW/...BUT THE COMBO OF A TENTH OF AN INCH OF FZRA BEING TOPPED WITH 3 TO 5 INCHES OF SNOW WARRANTS KEEPING THE WARNING GOING...THOUGH WOULD SUSPECT IT CAN BE PULLED BEFORE 6Z. WILL GET A BREAK IN THE PRECIP MOST OF THE DAY MONDAY...BEFORE THE MAIN TROUGH CURRENTLY ACROSS THE ROCKIES BEGINS PROGRESSING ACROSS THE PLAINS. WHAT WILL MAKE THIS PRECIP EVENT DIFFICULT FROM THE P-TYPE PERSPECTIVE IS THAT AS TODAYS PRECIP MOVES OUT...THE WARM NOSE WILL MOVE BACK IN...WITH ANOTHER MELTING LAYER IN PLACE MONDAY AFTERNOON AS THIS NEXT SYSTEM MOVES IN. MAIN SFC LOW IS FORECAST TO GO FROM NW KS MONDAY AFTERNOON TO THE U.P. OF MICH BY TUESDAY AFTERNOON. ALL MODELS SHOWING TWO BATCHES OF PRECIP WITH THIS SYSTEM. LLJ WARM SECTOR PRECIP LOOKS TO STAY WELL SE OF THE AREA...WHILE ANOTHER INTENSE BAND OF FGEN INDUCED SNOW MOVES ACROSS WRN INTO NE MN. WITH THIS SIGNAL...UPPED POPS TO THE CATEGORICAL RANGE IN THE NW CWA MONDAY NIGHT...WITH 2-3 INCHES OF SNOW UP IN THE MORRIS/ALEX AREA. CONFIDENCE ON PRECIP OCCURRENCE ACROSS THE REST OF THE AREA IS A BIT LOWER AS THESE TWO BATCHES OF PRECIP SPLIT THE AREA...BUT WHATEVER HAPPENS MONDAY NIGHT WITH PRECIP IN THE ERN 2/3RDS OF THE CWA...FORECAST SOUNDINGS AGAIN SAY THE P-TYPE WILL BE RA OR FZRA DEPENDING ON THE SFC TEMP. AFTER NEARLY STEADY TEMPERATURES TODAY THROUGH TUESDAY...THE ENCROACHMENT OF ANOTHER ARCTIC HIGH FOR THE END OF THE WEEK WILL LEAD TO A SIGNIFICANT COOL DOWN STARTING TUESDAY NIGHT. WILL SEE STRONG CAA ALL DAY WEDNESDAY RIGHT THROUGH WEDNESDAY NIGHT AS HIGH PRESSURE GOES FROM THE DAKOTAS OVER TO THE KANSAS CITY AREA BY FRIDAY MORNING. WILL SEE ANOTHER HEALTHY SURGE OF COLD BEHIND THIS SYSTEM...WITH H85 TEMPS BY THURSDAY AGAIN BACK BETWEEN 25 C AND 30 C BELOW ZERO. THIS WILL GIVE MUCH OF THE MN CWA ANOTHER SHOT AT SEEING SUB ZERO HIGHS THURSDAY AFTERNOON. FOR FRIDAY THROUGH THE WEEKEND...A MODERATION IN TEMPERATURES IS EXPECTED AS A CLIPPER SLIDES ACROSS NRN MN AND WI FRI NIGHT/SATURDAY. MAY SEE A QUICK 1-2 INCHES OF SNOW OUT OF THIS WITH CURRENT INDICATIONS BEING THAT THE BEST CHANCE FOR ACCUMULATING SNOW WILL BE NORTH OF I-94. && .AVIATION.../06Z TAF ISSUANCE/ NOT MUCH PRECIP REMAINING...BUT FOG WILL BE A CONCERN COME MORNING AT MOST OF THE TAF SITES...ESPECIALLY THOSE IN MN. DENSE FOG WITH 1/4SM OR LESS HAS BEEN SLOWLY ADVECTING EASTWARD OUT OF THE DAKOTAS. KAXN/KRWF AND EVEN KSTC SHOULD SEE LIFR VIS BY SUNRISE...HAVE ALSO INCLUDED IFR FOG IN EASTERN MN AND WESTERN WI...BUT DIDN`T GO 1/4SM YET. WINTRY MIX CHANGING OVER TO SNOW EXPECTED TO FROM WEST TO EAST ACROSS AREA LATE THIS AFTERNOON INTO THE EVENING. REGARDLESS...SHOULD BE IFR ALL DAY AND NIGHT. KMSP... STILL POTENTIAL FOR 1/4SM DENSE FOG AT SOME POINT LATE IN THE MORNING...BUT PLAYED IT A LITTLE CONSERVATIVE AT THE AIRPORT FOR NOW. HOWEVER...HIGH CONFIDENCE IN IFR ALL DAY...BUT THERE SHOULDN`T BE ANY NEW PRECIP UNTIL THIS EVENING. PRECIP COULD ARRIVE AS EARLY AS THE LAST HALF OF THE EVENING COMMUTE...BUT MORE LIKELY WILL HOLD OFF UNTIL THE LATE EVENING AND COME IN AS A WINTRY MIX BEFORE CHANGING OVER TO SNOW LATE TONIGHT. /OUTLOOK FOR KMSP/ TUE...MVFR/IFR CONDITIONS IN THE MORNING...MVFR CIGS BY AFTERNOON. CHC -SN IN THE MORNING. NW WIND 5-10KT. WED...MVFR CIGS. NW WIND 15G25KT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST MONDAY FOR ANOKA-BENTON- BLUE EARTH-BROWN-CARVER-CHIPPEWA-CHISAGO-DAKOTA-DOUGLAS- FARIBAULT-FREEBORN-GOODHUE-HENNEPIN-ISANTI-KANABEC- KANDIYOHI-LAC QUI PARLE-LE SUEUR-MARTIN-MCLEOD-MEEKER-MILLE LACS-MORRISON-NICOLLET-POPE-RAMSEY-REDWOOD-RENVILLE-RICE- SCOTT-SHERBURNE-SIBLEY-STEARNS-STEELE-STEVENS-SWIFT-TODD- WASECA-WASHINGTON-WATONWAN-WRIGHT-YELLOW MEDICINE. WI...WINTER WEATHER ADVISORY UNTIL 6 AM CST MONDAY FOR BARRON- CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX. && $$ MPG/CLF
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1229 PM CST Mon Jan 28 2013 .UPDATE... /1216 PM CST Mon Jan 28 2013/ Warm front has begun to lift across the forecast region, which has rapidly cleared skies across the southern 3/4 of the forecast area. Clouds across southern Missouri may move back in, but they will be far more scattered in nature, so have gone ahead and upped temperatures for areas along and south of the Missouri River. Have also bumped temperatures along the Iowa border as the fog is disipating and clouds are thinning out, though did not warm them as much. Cutter && .DISCUSSION... Unseasonable warmth and copious moisture has overspread the region this morning. This will set the stage for some potentially active weather tonight and Tuesday as a strong system interacts with this warm airmass. For today, frontal boundary is settling southward to near a Kansas City to Kirksville line where it will begin to stall through the morning. Cold air behind the front and copious low-level moisture have led to widespread dense fog over the northwest forecast area where a dense fog advisory has been issued through noon. How soon the fog will lift is still in question, so decided to play it liberally and take the advisory as late as noon to give the airmass plenty of time to start mixing as the frontal boundary lifts north through the day. Temperatures today could approach or exceed record territory for Kansas City (record high is 65 set in 1917), but a lot depends on when or if the widespread stratus deck in place can start to mix out. This deck looks quite thick and latest NAM and RAP models indicate it could hang around all day long for most of the forecast area. See no reason to go against these models, so kept skies cloudy through the day and as a result nudged temperatures down a few degrees area-wide. Still, with the southern half of the KC metro still sitting at 61 degrees at 3 AM and parts of northern Oklahoma in the middle 60s, simple warm air advection alone should be able to send areas south of the Highway 36 corridor into the middle and upper 60s this afternoon despite widespread cloud cover. Areas further north are likely to see fog, low clouds and drizzle stick around for much of the afternoon until the front lifts through, so took temperatures down several degrees for these areas. Forecast gets interesting tonight and Tuesday as a strong upper trough deepens across the Central Plains and moves into this unseasonably warm airmass. This is likely to result in widespread showers and thunderstorms developing along a cold front that will move through the forecast area early Tuesday. However, there could be some scattered convection developing ahead of the front as early as midnight tonight over parts of the forecast area as hinted at by nearly every model. With the front and upper trough still west of the area tonight, large-scale ascent will be quite limited with forcing mainly coming from broad and weak low-level convergence and isentropic ascent. However, models are suggesting weak yet almost uninhibited surface-based instability developing across the western and southern forecast area overnight. This combined with very high low-level shear and very low LCL heights could favor a damaging wind and/or tornado risk with any storms that do develop. Will keep an eye on this overnight, but for now expect the overall severe threat to stay low until the arrival of the cold front can provide persistent forcing for any organized convection given the high shear/low instby combo. Most models have slowed down the arrival of Tuesday`s cold front, now poised to enter northwest Missouri around 12Z, reaching the I-35 corridor around 18Z and the southeast CWA border around 00Z. Expect one or more lines of convection to develop near and ahead of the front which could develop as early as 12Z over the northwest CWA Tuesday morning. Instability will remain rather weak (<1000 J/kg) but continued strong low-level shear will favor thin convective lines capable of small bows and possible low-level rotation and tornadoes as far west as I-35 Tuesday morning, moving into central MO through the afternoon. Finally, as the front pushes into eastern MO Tuesday night and Wednesday, a few models are suggesting a weak wave riding up the boundary in response to a vort max rounding the base of the large upper trough. Such a feature could produce light rain/snow across the eastern forecast area with the potential for accumulating snow looking low at this time. Hawblitzel Medium Range (Thursday through Monday): Little change in reasoning to current extended forecast period with this issuance. Another shot of cold air is projected to enter the region on Thursday as an upper wave on the backside of the eastern CONUS longwave trough dives into the Ohio Valley. The cold air will remain in place through Friday as surface high pressure moves across the area. Temperatures will be below normal Thursday into Friday, with highs on Thursday only reaching the 20s to lower 30s. The coldest air of the forecast period is anticipated on Thursday night into Friday morning upon clear skies and light winds, with low temperatures in the single digits and teens. Surface high pressure moves off to the east on Friday night with northwest flow aloft persisting through the remainder of the forecast. A gradual moderation of temperatures and dry weather is anticipated during this period. The overall pattern suggested by operational guidance shows an upper ridge developing over the western CONUS by the end of the weekend, but confidence is not particularly high on the details of the evolution of large-scale features and likewise temperatures by the end of the period. Blair && .AVIATION... For the 18Z TAFs...VFR conditions are rapidly spread north across the terminals as we close in on 18Z. Gusty south winds will spread into the sites as a result this afternoon. Low clouds, MVFR, will then move back in this evening. Pressure gradient will stay up through the overnight hours, so surface winds are not expected to decouple and will therefore stay above 12 knots all night long. Additionally, with the strong surface winds comes a strong low level jet, so have also included wind shear, though it will shift east of the terminals early Tuesday morning. Lastly, included some VCTS and PROB30`s for thunderstorms Tuesday morning. Much of the stormy activity is expected to be east of the terminals, but some scattered activity might develop far enough west to impact them in the morning. A front progressing through the Central Plains will shove the thunderstorm activity farther east during the afternoon hours. Cutter && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1152 AM CST Mon Jan 28 2013 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... Unseasonable warmth and copious moisture has overspread the region this morning. This will set the stage for some potentially active weather tonight and Tuesday as a strong system interacts with this warm airmass. For today, frontal boundary is settling southward to near a Kansas City to Kirksville line where it will begin to stall through the morning. Cold air behind the front and copious low-level moisture have led to widespread dense fog over the northwest forecast area where a dense fog advisory has been issued through noon. How soon the fog will lift is still in question, so decided to play it liberally and take the advisory as late as noon to give the airmass plenty of time to start mixing as the frontal boundary lifts north through the day. Temperatures today could approach or exceed record territory for Kansas City (record high is 65 set in 1917), but a lot depends on when or if the widespread stratus deck in place can start to mix out. This deck looks quite thick and latest NAM and RAP models indicate it could hang around all day long for most of the forecast area. See no reason to go against these models, so kept skies cloudy through the day and as a result nudged temperatures down a few degrees area-wide. Still, with the southern half of the KC metro still sitting at 61 degrees at 3 AM and parts of northern Oklahoma in the middle 60s, simple warm air advection alone should be able to send areas south of the Highway 36 corridor into the middle and upper 60s this afternoon despite widespread cloud cover. Areas further north are likely to see fog, low clouds and drizzle stick around for much of the afternoon until the front lifts through, so took temperatures down several degrees for these areas. Forecast gets interesting tonight and Tuesday as a strong upper trough deepens across the Central Plains and moves into this unseasonably warm airmass. This is likely to result in widespread showers and thunderstorms developing along a cold front that will move through the forecast area early Tuesday. However, there could be some scattered convection developing ahead of the front as early as midnight tonight over parts of the forecast area as hinted at by nearly every model. With the front and upper trough still west of the area tonight, large-scale ascent will be quite limited with forcing mainly coming from broad and weak low-level convergence and isentropic ascent. However, models are suggesting weak yet almost uninhibited surface-based instability developing across the western and southern forecast area overnight. This combined with very high low-level shear and very low LCL heights could favor a damaging wind and/or tornado risk with any storms that do develop. Will keep an eye on this overnight, but for now expect the overall severe threat to stay low until the arrival of the cold front can provide persistent forcing for any organized convection given the high shear/low instby combo. Most models have slowed down the arrival of Tuesday`s cold front, now poised to enter northwest Missouri around 12Z, reaching the I-35 corridor around 18Z and the southeast CWA border around 00Z. Expect one or more lines of convection to develop near and ahead of the front which could develop as early as 12Z over the northwest CWA Tuesday morning. Instability will remain rather weak (<1000 J/kg) but continued strong low-level shear will favor thin convective lines capable of small bows and possible low-level rotation and tornadoes as far west as I-35 Tuesday morning, moving into central MO through the afternoon. Finally, as the front pushes into eastern MO Tuesday night and Wednesday, a few models are suggesting a weak wave riding up the boundary in response to a vort max rounding the base of the large upper trough. Such a feature could produce light rain/snow across the eastern forecast area with the potential for accumulating snow looking low at this time. Hawblitzel Medium Range (Thursday through Monday): Little change in reasoning to current extended forecast period with this issuance. Another shot of cold air is projected to enter the region on Thursday as an upper wave on the backside of the eastern CONUS longwave trough dives into the Ohio Valley. The cold air will remain in place through Friday as surface high pressure moves across the area. Temperatures will be below normal Thursday into Friday, with highs on Thursday only reaching the 20s to lower 30s. The coldest air of the forecast period is anticipated on Thursday night into Friday morning upon clear skies and light winds, with low temperatures in the single digits and teens. Surface high pressure moves off to the east on Friday night with northwest flow aloft persisting through the remainder of the forecast. A gradual moderation of temperatures and dry weather is anticipated during this period. The overall pattern suggested by operational guidance shows an upper ridge developing over the western CONUS by the end of the weekend, but confidence is not particularly high on the details of the evolution of large-scale features and likewise temperatures by the end of the period. Blair && .AVIATION... For the 18Z TAFs...VFR conditions are rapidly spread north across the terminals as we close in on 18Z. Gusty south winds will spread into the sites as a result this afternoon. Low clouds, MVFR, will then move back in this evening. Pressure gradient will stay up through the overnight hours, so surface winds are not expected to decouple and will therefore stay above 12 knots all night long. Additionally, with the strong surface winds comes a strong low level jet, so have also included wind shear, though it will shift east of the terminals early Tuesday morning. Lastly, included some VCTS and PROB30`s for thunderstorms Tuesday morning. Much of the stormy activity is expected to be east of the terminals, but some scattered activity might develop far enough west to impact them in the morning. A front progressing through the Central Plains will shove the thunderstorm activity farther east during the afternoon hours. Cutter && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
554 AM CST Mon Jan 28 2013 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... Unseasonable warmth and copious moisture has overspread the region this morning. This will set the stage for some potentially active weather tonight and Tuesday as a strong system interacts with this warm airmass. For today, frontal boundary is settling southward to near a Kansas City to Kirksville line where it will begin to stall through the morning. Cold air behind the front and copious low-level moisture have led to widespread dense fog over the northwest forecast area where a dense fog advisory has been issued through noon. How soon the fog will lift is still in question, so decided to play it liberally and take the advisory as late as noon to give the airmass plenty of time to start mixing as the frontal boundary lifts north through the day. Temperatures today could approach or exceed record territory for Kansas City (record high is 65 set in 1917), but a lot depends on when or if the widespread stratus deck in place can start to mix out. This deck looks quite thick and latest NAM and RAP models indicate it could hang around all day long for most of the forecast area. See no reason to go against these models, so kept skies cloudy through the day and as a result nudged temperatures down a few degrees area-wide. Still, with the southern half of the KC metro still sitting at 61 degrees at 3 AM and parts of northern Oklahoma in the middle 60s, simple warm air advection alone should be able to send areas south of the Highway 36 corridor into the middle and upper 60s this afternoon despite widespread cloud cover. Areas further north are likely to see fog, low clouds and drizzle stick around for much of the afternoon until the front lifts through, so took temperatures down several degrees for these areas. Forecast gets interesting tonight and Tuesday as a strong upper trough deepens across the Central Plains and moves into this unseasonably warm airmass. This is likely to result in widespread showers and thunderstorms developing along a cold front that will move through the forecast area early Tuesday. However, there could be some scattered convection developing ahead of the front as early as midnight tonight over parts of the forecast area as hinted at by nearly every model. With the front and upper trough still west of the area tonight, large-scale ascent will be quite limited with forcing mainly coming from broad and weak low-level convergence and isentropic ascent. However, models are suggesting weak yet almost uninhibited surface-based instability developing across the western and southern forecast area overnight. This combined with very high low-level shear and very low LCL heights could favor a damaging wind and/or tornado risk with any storms that do develop. Will keep an eye on this overnight, but for now expect the overall severe threat to stay low until the arrival of the cold front can provide persistent forcing for any organized convection given the high shear/low instby combo. Most models have slowed down the arrival of Tuesday`s cold front, now poised to enter northwest Missouri around 12Z, reaching the I-35 corridor around 18Z and the southeast CWA border around 00Z. Expect one or more lines of convection to develop near and ahead of the front which could develop as early as 12Z over the northwest CWA Tuesday morning. Instability will remain rather weak (<1000 J/kg) but continued strong low-level shear will favor thin convective lines capable of small bows and possible low-level rotation and tornadoes as far west as I-35 Tuesday morning, moving into central MO through the afternoon. Finally, as the front pushes into eastern MO Tuesday night and Wednesday, a few models are suggesting a weak wave riding up the boundary in response to a vort max rounding the base of the large upper trough. Such a feature could produce light rain/snow across the eastern forecast area with the potential for accumulating snow looking low at this time. Hawblitzel Medium Range (Thursday through Monday): Little change in reasoning to current extended forecast period with this issuance. Another shot of cold air is projected to enter the region on Thursday as an upper wave on the backside of the eastern CONUS longwave trough dives into the Ohio Valley. The cold air will remain in place through Friday as surface high pressure moves across the area. Temperatures will be below normal Thursday into Friday, with highs on Thursday only reaching the 20s to lower 30s. The coldest air of the forecast period is anticipated on Thursday night into Friday morning upon clear skies and light winds, with low temperatures in the single digits and teens. Surface high pressure moves off to the east on Friday night with northwest flow aloft persisting through the remainder of the forecast. A gradual moderation of temperatures and dry weather is anticipated during this period. The overall pattern suggested by operational guidance shows an upper ridge developing over the western CONUS by the end of the weekend, but confidence is not particularly high on the details of the evolution of large-scale features and likewise temperatures by the end of the period. Blair && .AVIATION... For the 12Z TAFs...weak front has nudged south to near an MKC-IRK line. This front will stall near this position then return north as a warm front through the morning. Widespread dense fog has settled in north of this boundary, with a well-defined southern edge about 60 nm north of the surface boundary from near SLN to 25 nm N of STJ to BRL. Satellite trends show that this fog has ceased moving southward and should begin retreating northward through the morning, leaving STJ and KC terminals unaffected. Main concern for the STJ/MKC/MCI TAF sites will be stratus deck which is currently MVFR (small band of DZ and very low cigs near MCI is dissipating). Model soundings continue to show these clouds lowering into IFR for much of the morning and then lifting back into MVFR late in the day. Confidence on this happening is not terribly high, but IFR cigs do exist further southwest across cntrl/eastern KS so will go ahead and bring these into the terminals later this morning. If/when these low cigs lift back into MVFR is quite questionable but best bet is that daytime heating brings cigs back to MVFR by afternoon. Could see some scattered showers or convection develop overnight but better chances are after 12Z Tues. Not enough confidence to introduce TS/CB at this time. Considered LLWS overnight with strong 50-kt winds at 2 kft, but low level winds look to gradually increase with height versus a sharp increase, so kept it out for now. Hawblitzel && .EAX WATCHES/WARNINGS/ADVISORIES... MO...DENSE FOG ADVISORY until Noon CST today FOR MOZ001>008-011. KS...NONE. && $$ WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
352 AM CST Mon Jan 28 2013 .DISCUSSION... Unseasonable warmth and copious moisture has overspread the region this morning. This will set the stage for some potentially active weather tonight and Tuesday as a strong system interacts with this warm airmass. For today, frontal boundary is settling southward to near a Kansas City to Kirksville line where it will begin to stall through the morning. Cold air behind the front and copious low-level moisture have led to widespread dense fog over the northwest forecast area where a dense fog advisory has been issued through noon. How soon the fog will lift is still in question, so decided to play it liberally and take the advisory as late as noon to give the airmass plenty of time to start mixing as the frontal boundary lifts north through the day. Temperatures today could approach or exceed record territory for Kansas City (record high is 65 set in 1917), but a lot depends on when or if the widespread stratus deck in place can start to mix out. This deck looks quite thick and latest NAM and RAP models indicate it could hang around all day long for most of the forecast area. See no reason to go against these models, so kept skies cloudy through the day and as a result nudged temperatures down a few degrees area-wide. Still, with the southern half of the KC metro still sitting at 61 degrees at 3 AM and parts of northern Oklahoma in the middle 60s, simple warm air advection alone should be able to send areas south of the Highway 36 corridor into the middle and upper 60s this afternoon despite widespread cloud cover. Areas further north are likely to see fog, low clouds and drizzle stick around for much of the afternoon until the front lifts through, so took temperatures down several degrees for these areas. Forecast gets interesting tonight and Tuesday as a strong upper trough deepens across the Central Plains and moves into this unseasonably warm airmass. This is likely to result in widespread showers and thunderstorms developing along a cold front that will move through the forecast area early Tuesday. However, there could be some scattered convection developing ahead of the front as early as midnight tonight over parts of the forecast area as hinted at by nearly every model. With the front and upper trough still west of the area tonight, large-scale ascent will be quite limited with forcing mainly coming from broad and weak low-level convergence and isentropic ascent. However, models are suggesting weak yet almost uninhibited surface-based instability developing across the western and southern forecast area overnight. This combined with very high low-level shear and very low LCL heights could favor a damaging wind and/or tornado risk with any storms that do develop. Will keep an eye on this overnight, but for now expect the overall severe threat to stay low until the arrival of the cold front can provide persistent forcing for any organized convection given the high shear/low instby combo. Most models have slowed down the arrival of Tuesday`s cold front, now poised to enter northwest Missouri around 12Z, reaching the I-35 corridor around 18Z and the southeast CWA border around 00Z. Expect one or more lines of convection to develop near and ahead of the front which could develop as early as 12Z over the northwest CWA Tuesday morning. Instability will remain rather weak (<1000 J/kg) but continued strong low-level shear will favor thin convective lines capable of small bows and possible low-level rotation and tornadoes as far west as I-35 Tuesday morning, moving into central MO through the afternoon. Finally, as the front pushes into eastern MO Tuesday night and Wednesday, a few models are suggesting a weak wave riding up the boundary in response to a vort max rounding the base of the large upper trough. Such a feature could produce light rain/snow across the eastern forecast area with the potential for accumulating snow looking low at this time. Hawblitzel Medium Range (Thursday through Monday): Little change in reasoning to current extended forecast period with this issuance. Another shot of cold air is projected to enter the region on Thursday as an upper wave on the backside of the eastern CONUS longwave trough dives into the Ohio Valley. The cold air will remain in place through Friday as surface high pressure moves across the area. Temperatures will be below normal Thursday into Friday, with highs on Thursday only reaching the 20s to lower 30s. The coldest air of the forecast period is anticipated on Thursday night into Friday morning upon clear skies and light winds, with low temperatures in the single digits and teens. Surface high pressure moves off to the east on Friday night with northwest flow aloft persisting through the remainder of the forecast. A gradual moderation of temperatures and dry weather is anticipated during this period. The overall pattern suggested by operational guidance shows an upper ridge developing over the western CONUS by the end of the weekend, but confidence is not particularly high on the details of the evolution of large-scale features and likewise temperatures by the end of the period. Blair && .AVIATION... For the 06Z TAFs: MVFR stratus continues to expand throughout eastern Kansas and northern Missouri tonight and will remain entrenched through at least mid-day Monday. Models in general have backed off on the development of very low LIFR visibility and ceilings around daybreak. However, still feel the development of IFR ceilings will be likely after 09z as a frontal boundary drops into northern Missouri. Expecting stratus to remain in place along and north of the aforementioned front through early afternoon before erosion rapidly begins in southeastern Kansas and spreads northeast. Ceilings should quickly scatter or lift by 21Z as warm air pours northward. VFR conditions should prevail Monday evening in most locations, as a warm front lifts well into Iowa. Low confidence at this stage and haven`t included in current TAF, but scattered showers or even thunder may develop Monday evening. 31 && .EAX WATCHES/WARNINGS/ADVISORIES... MO...DENSE FOG ADVISORY until Noon CST today FOR MOZ001>003-011. KS...NONE. && $$ WFO EAX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
728 PM CST TUE JAN 29 2013 .UPDATE...EVENING UPPER AIR ANALYSIS INDICATES A LONGWAVE TROUGH OVER THE CENTRAL CONUS...WITH RIDGING OVER THE EAST AND WEST. MID AND UPPER LEVEL JET ENERGY EXTENDS SOUTH/SOUTHEAST FROM SOUTHWEST CANADA INTO THE FOUR CORNERS REGION...AND THEN EAST INTO THE SOUTHERN PLAINS BEFORE TURNING NORTHEAST ACROSS PORTIONS OF THE CENTRAL PLAINS AND MISSISSIPPI VALLEY. ALTHOUGH THE PRIMARY AXIS OF THIS JET ENERGY REMAIN JUST EAST/SOUTHEAST OF OUR CWA...RAP DATA DOES SUGGEST WIND SPEEDS GENERALLY RANGING FROM 50-100KTS IN EXISTENCE FROM WEST TO EAST ACROSS OUR CWA AROUND 400MB...WITH THE STRONGEST WIND RESIDING ACROSS OUR EAST. WATER VAPOR IMAGERY SHOWS INCREASED VALUES OF MID LEVEL MOISTURE EXTENDING FROM EASTERN TEXAS...NORTHEAST INTO THE MID MISSISSIPPI VALLEY...AND A MID LEVEL DRY INTRUSION WORKING INTO THE CENTRAL PLAINS. AT THE SURFACE A COLD FRONT IS NOTED EXTENDING FROM CENTRAL MISSOURI...SOUTHWEST INTO PORTIONS OF KANSAS...OKLAHOMA AND TEXAS. OUR CWA IS CURRENTLY ON THE BACK SIDE OF THIS FRONT WITH A NORTHERLY LOW LEVEL WIND FIELD PREVAILING ACROSS THE AREA AS A RESULT. RADAR DATA FROM KUEX INDICATES BANDED PRECIPITATION OVER THE SOUTHEASTERN HALF OF OUR CWA...HOWEVER COMMUNICATION WITH OBSERVERS HAVE YIELDED LITTLE MORE THAN TRACE REPORTS OF SNOWFALL ACCUMULATION THIS EVENING...ALTHOUGH ACCUMULATION IS UNDOUBTEDLY BEGINNING TO OCCUR ALONG AND EAST OF HIGHWAY 281 NOW. GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL SUGGEST PORTIONS OF THE LONGWAVE TROUGH NEAR OUR AREA WILL STRENGTHEN INTO A SHORT WAVE FEATURE AS IT PUSHES OVER PORTIONS OF NEBRASKA AND KANSAS...AND EVENTUALLY INTO IOWA AND MISSOURI TONIGHT. AS MID LEVEL VORTICITY INCREASES WITH THE STRENGTHENING MID LEVEL SHORT WAVE...SO WILL MID LEVEL DEFORMATION TO THE WEST/NORTHWEST OF THE MID LEVEL SHORT WAVE AXIS...WITH THE PRIMARY AXIS OF MID LEVEL DEFORMATION EXPECTED TO PERSIST FROM EASTERN NEBRASKA...INTO PORTIONS OF SOUTH CENTRAL NEBRASKA AND NORTH CENTRAL KANSAS THIS EVENING...AND THEN EAST INTO WESTERN IOWA AND SOUTHEASTERN NEBRASKA BY 06Z TONIGHT. THIS AXIS OF DEFORMATION AND RESULTANT MID LEVEL FRONTOGENESIS...PRIMARILY NEAR 700MB...WILL CONTINUE TO PROVIDE BANDED PRECIPITATION ACROSS PORTIONS OF OUR AREA THROUGH AT LEAST 06Z...WITH THE EAST/SOUTHEASTERN PORTIONS OF OUR CWA STILL UNDER THE GUN TO RECEIVE A DECENT ROUND OF FRESH SNOWFALL THIS EVENING. FORECAST CROSS SECTIONS ALSO INDICATE A WEAK ZONE OF -EPV WILL PERIODICALLY EXIST JUST ABOVE THE MID LEVEL FRONTOGENESIS THIS EVENING...WHICH INDICATES AT LEAST SOME SLANT- WISE CONVECTION AND A POSSIBILITY FOR INCREASED PRECIPITATION RATES. THE CURRENT THINKING IS THAT THIS AREA OF BANDED PRECIPITATION WILL CONTINUE SHIFTING EAST/NORTHEAST ALONG WITH THE PRIMARY AXIS OF MID LEVEL FRONTOGENEIS THROUGH TONIGHT...WITH PRECIPITATION RATES INCREASING AS THE AFOREMENTIONED MID LEVEL FRONTOGENESIS ALSO INTENSIFIES ACROSS EAST/SOUTHEASTERN PORTIONS OF OUR CWA. PRECIPITATION SHOULD THEN TAPER OFF ACROSS OUR CWA STARTING AROUND 06Z AS THE PRIMARY AXIS OF MID LEVEL FRONTOGENESIS ALSO MOVES EAST OF OUR AREA. THIS IS A SOLUTION SUPPORTED BY QPF FIELDS FROM THE NAM...OPERATIONAL GFS...EC...SREF-MEAN...RAP...HRRR...AND 4KM WRF- NMM. EXACT LIQUID PRECIPITATION AMOUNTS VARY FROM MODEL TO MODEL...BUT IN GENERAL THEY AVERAGE BETWEEN 0.1" AND 0.2" ACROSS OUR SOUTHEAST. WITH LOWER TROPOSPHERIC TEMPERATURE EXPECTED TO AVERAGE IN THE UPPER 20S TO NEAR 30 DEGREES F...WILL GO AHEAD AND ASSUME AN AVERAGE SNOW-WATER RATIO OF 12:1...WHICH PRESENTS SNOWFALL ACCUMULATION GENERALLY IN THE 1-2.5" RANGE. GIVEN THE POTENTIAL FOR MODEST SLANT-WISE CONVECTION HOWEVER...WILL GO AHEAD AND ADD ANOTHER INCH TO THE MODEL OUTPUT WHICH PROVIDES SNOWFALL ACCUMULATION CLOSER TO THE 2-4" RANGE. IN ADDITION TO THE SNOWFALL...LOW LEVEL PRESSURE RISES BEHIND THE LOW LEVEL BAROCLINIC ZONE...CURRENTLY TO OUR SOUTH...ARE EXPECTED TO INDUCE A STRENGTHENING LOW LEVEL PRESSURE GRADIENT TONIGHT. GUIDANCE FROM THE MET AND MAV SUGGEST A SUSTAINED WIND AVERAGING BETWEEN 15 AND 20KTS...WITH LOCALLY HIGHER GUSTS...WILL BE COMMON ACROSS OUR CWA DURING THE SNOWFALL WHICH WILL CERTAINLY CREATE SOME VISIBILITY RESTRICTION IN BLOWING SNOW. OVERALL THE TIMING AND POSITION OF THE CURRENT WINTER WEATHER ADVISORY ARE IN GREAT SHAPE...SO MADE NO CHANGES THERE. OUR FORECAST SNOWFALL AMOUNTS DID SEEM A TOUCH ON THE HIGH SIDE BASED ON THE LATEST MODEL OUTPUT...SO DID GO AHEAD AND DECREASE SNOWFALL ACCUMULATION DOWN INTO THE 2-4" RANGE FOR THE ADVISORY AREA. REMAINDER OF THE FORECAST REMAINS IN GREAT SHAPE WITH ONLY MINOR CHANGES MADE TO HOURLY TEMPERATURE...WIND AND DEWPOINTS GRIDS TO BETTER REFLECT CURRENT CONDITIONS. && .PREV DISCUSSION... /ISSUED 533 PM CST TUE JAN 29 2013/ AVIATION...00Z KGRI TAF. MVFR CEILINGS EXPECTED THROUGH THE FIRST HALF OF THE TAF PERIOD WITH LIGHT SNOW ALSO EXPECTED TO PERSIST THROUGH VERY EARLY WEDNESDAY MORNING. VISIBILITY RESTRICTION IN BLOWING SNOW WILL ALSO BE POSSIBLE LATER TONIGHT AS THE NORTH WIND INTENSIFIES. VFR CONDITIONS SHOULD BE RESTORED SHORTLY AFTER SUNRISE WEDNESDAY. PREV DISCUSSION... /ISSUED 358 PM CST TUE JAN 29 2013/ SHORT TERM...TONIGHT AND WEDNESDAY. HIGHLY AMPLIFIED MEAN TROUGH IS HEADING EAST WITH THE AXIS CROSSING INTO THE HIGH PLAINS. STRONG JET AHEAD OF THIS AXIS WITH STIFF MID-LEVEL FRONTOGENETIC FORCING PREDICTED TO RAMP UP THIS EVENING. THIS IS SUPPORTED BY THE NAM...HRRR...ECMWF...AND GFS...ALL PLACING DECENT QPF AMOUNTS IN THE EAST/SOUTHEAST PART OF THE CWA AT THE VERY LEAST. THIS AGREEMENT AMONG MODELS HAS LED ME TO INCREASE CHANCES OF PRECIPITATION EVEN MORE. SOUNDINGS INDICATE THAT THIS WILL BE A SNOW EVENT AND HAVE GONE WITH ONLY SNOW AS THE PRECIPITATION TYPE...AS OPPOSED TO MENTIONING RAIN AT ONSET. THE HRRR INDICATE4D QUITE A RAMP UP IN QPF PRODUCTION BY EARLY AFTERNOON...WHICH PROMPTED ME TO GO WITH AN ADVISORY FOR MOST OF OUR EASTERN CWA. I FELT INCLINED TO DO THIS AS NORTH/NORTHWEST WIND WILL RAMP UP CONSIDERABLY TONIGHT AS THE SURFACE PRESSURE GRADIENT INCREASES. I INCREASED WIND SPEEDS A BIT MORE FROM THE PREVIOUS FORECAST FOR TONIGHT INTO WEDNESDAY. SNOW SHOULD WIND DOWN FAIRLY QUICKLY AS THE TROUGH AXIS HEADS TO THE EAST BY THE OVERNIGHT. LEFT THE SLIGHT CHANCE OF FLURRIES IN OUR NORTHEAST FOR WEDNESDAY MORNING...BUT I DID NOTICE THE NAM PULLING BACK A LITTLE ON STRATUS...WHICH USUALLY INDICATES A LACK OF FLURRY POTENTIAL...BUT CLOSE ENOUGH FOR ME TO LEAVE IN FOR NOW. WIND SHOULD REMAIN BELOW WIND ADVISORY CRITERIA FOR WEDNESDAY...ALTHOUGH OUR FAR NORTH MAY FLIRT WITH IT...JUDGING BY PREDICTED MOMENTUM TRANSFER. KEPT SKY COVER GENERALLY CLOUDY...ALTHOUGH THERE COULD BE SOME BREAKS...ESPECIALLY IN THE SOUTH BY AFTERNOON. KEPT TEMPERATURES THE SAME FOR TONIGHT AND WEDNESDAY FROM PREVIOUS FORECAST AS THEY LOOKED LIKE THEY WERE RIGHT ON TARGET. LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY. MAIN FORECAST CONCERN IN THE EXTENDED WILL BE THE TEMPERATURES. STARTING WED EVENING...THE BIG PICTURE SHOWS THE CENTRAL U.S. IN NORTHWEST FLOW AS THE UPPER TROUGH IS SLATED TO BE MOVING INTO THE MIDWEST WITH RIDGING MOVING ONTO THE PACIFIC NORTHWEST COAST. AS THE WORK WEEK ROLLS ALONG IT APPEARS WE WILL PRETTY MUCH STAY IN THIS TYPE OF FLOW WITH OVERALL RIDGING TO THE WEST AND TROUGHING EAST. WILL MOST LIKELY HAVE A FEW CLIPPER LIKE WAVES SLIDE THROUGH OUR REGION UNDER THIS TYPE OF PATTERN AND THE QUESTION IS WILL THEY BRING ANY ADDITIONAL PRECIPITATION CHANCES. BASIC ANSWER IS NO ALTHOUGH WE DO HAVE A CHANCE OF FLURRIES MENTIONED FOR WED NIGHT AND THURSDAY IN THE CURRENT FORECAST AND WILL GO AHEAD AND KEEP THEM IN GIVEN SUFFICIENT MOISTURE AND COLDER TEMPERATURES NOTED IN MODEL FORECAST SOUNDINGS. OTHERWISE WILL LEAVE THE REST OF THE FORECAST DRY ALTHOUGH SOME LIGHT PRECIPITATION NOT TOTALLY OUT OF THE QUESTION FOR FRIDAY. AS FAR AS TEMPERATURES GO...IT WILL REMAIN QUITE CHILLY WED NIGHT INTO FRIDAY MORNING AS ADDITIONAL COLD AIR SLIDES DOWN FROM THE NORTH...ALTHOUGH THE BITTER COLD AIR SHOULD REMAIN JUST NORTHEAST OF THE CWA. STOUT NORTHWEST WINDS ARE ALSO EXPECTED AGAIN FOR THURSDAY AFTERNOON AS WE SIT BETWEEN 1038 MB HIGH PRESSURE OVER MONTANA/NDAK AND LOW PRESSURE ACROSS MISSOURI AND KANSAS. FRIDAY MORNING MIGHT BE THE COLDEST DAY OF THE WEEK DEPENDING ON WHETHER HIGH PRESSURE DROPS RIGHT OVER THE TOP OF US OR SLIDES A LITTLE TO THE EAST IN WHICH CASE WE MIGHT HAVE A MORE CLOUD COVER AND LIGHT SOUTHERLY FLOW. GOING INTO THE WEEKEND HEIGHTS BEGIN TO RISE AS WESTERN RIDGE STARTS TO MOVE EAST AND AT THIS POINT APPEARS BOTH SAT AND SUNDAY SHOULD BE CLOSE TO 50 DEGREES. ANOTHER WEAK FRONT IS EXPECTED TO PUSH ACROSS SUNDAY NIGHT OR MONDAY WITH HIGH TEMPERATURES FALLING A TAD BUT STILL ABOVE SEASONAL LEVELS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...WINTER WEATHER ADVISORY UNTIL 1 AM CST WEDNESDAY FOR NEZ049-063- 064-076-077-086-087. KS...WINTER WEATHER ADVISORY UNTIL 1 AM CST WEDNESDAY FOR KSZ007. && $$ 0728 PM UPDATE/AVIATION...BRYANT SHORT TERM...HEINLEIN LONG TERM...EWALD
AREA FORECAST DISCUSSION
NWS HASTINGS NE
533 PM CST TUE JAN 29 2013 .AVIATION...00Z KGRI TAF. MVFR CEILINGS EXPECTED THROUGH THE FIRST HALF OF THE TAF PERIOD WITH LIGHT SNOW ALSO EXPECTED TO PERSIST THROUGH VERY EARLY WEDNESDAY MORNING. VISIBILITY RESTRICTION IN BLOWING SNOW WILL ALSO BE POSSIBLE LATER TONIGHT AS THE NORTH WIND INTENSIFIES. VFR CONDITIONS SHOULD BE RESTORED SHORTLY AFTER SUNRISE WEDNESDAY. && .PREV DISCUSSION... /ISSUED 358 PM CST TUE JAN 29 2013/ SHORT TERM...TONIGHT AND WEDNESDAY. HIGHLY AMPLIFIED MEAN TROUGH IS HEADING EAST WITH THE AXIS CROSSING INTO THE HIGH PLAINS. STRONG JET AHEAD OF THIS AXIS WITH STIFF MID-LEVEL FRONTOGENETIC FORCING PREDICTED TO RAMP UP THIS EVENING. THIS IS SUPPORTED BY THE NAM...HRRR...ECMWF...AND GFS...ALL PLACING DECENT QPF AMOUNTS IN THE EAST/SOUTHEAST PART OF THE CWA AT THE VERY LEAST. THIS AGREEMENT AMONG MODELS HAS LED ME TO INCREASE CHANCES OF PRECIPITATION EVEN MORE. SOUNDINGS INDICATE THAT THIS WILL BE A SNOW EVENT AND HAVE GONE WITH ONLY SNOW AS THE PRECIPITATION TYPE...AS OPPOSED TO MENTIONING RAIN AT ONSET. THE HRRR INDICATE4D QUITE A RAMP UP IN QPF PRODUCTION BY EARLY AFTERNOON...WHICH PROMPTED ME TO GO WITH AN ADVISORY FOR MOST OF OUR EASTERN CWA. I FELT INCLINED TO DO THIS AS NORTH/NORTHWEST WIND WILL RAMP UP CONSIDERABLY TONIGHT AS THE SURFACE PRESSURE GRADIENT INCREASES. I INCREASED WIND SPEEDS A BIT MORE FROM THE PREVIOUS FORECAST FOR TONIGHT INTO WEDNESDAY. SNOW SHOULD WIND DOWN FAIRLY QUICKLY AS THE TROUGH AXIS HEADS TO THE EAST BY THE OVERNIGHT. LEFT THE SLIGHT CHANCE OF FLURRIES IN OUR NORTHEAST FOR WEDNESDAY MORNING...BUT I DID NOTICE THE NAM PULLING BACK A LITTLE ON STRATUS...WHICH USUALLY INDICATES A LACK OF FLURRY POTENTIAL...BUT CLOSE ENOUGH FOR ME TO LEAVE IN FOR NOW. WIND SHOULD REMAIN BELOW WIND ADVISORY CRITERIA FOR WEDNESDAY...ALTHOUGH OUR FAR NORTH MAY FLIRT WITH IT...JUDGING BY PREDICTED MOMENTUM TRANSFER. KEPT SKY COVER GENERALLY CLOUDY...ALTHOUGH THERE COULD BE SOME BREAKS...ESPECIALLY IN THE SOUTH BY AFTERNOON. KEPT TEMPERATURES THE SAME FOR TONIGHT AND WEDNESDAY FROM PREVIOUS FORECAST AS THEY LOOKED LIKE THEY WERE RIGHT ON TARGET. LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY. MAIN FORECAST CONCERN IN THE EXTENDED WILL BE THE TEMPERATURES. STARTING WED EVENING...THE BIG PICTURE SHOWS THE CENTRAL U.S. IN NORTHWEST FLOW AS THE UPPER TROUGH IS SLATED TO BE MOVING INTO THE MIDWEST WITH RIDGING MOVING ONTO THE PACIFIC NORTHWEST COAST. AS THE WORK WEEK ROLLS ALONG IT APPEARS WE WILL PRETTY MUCH STAY IN THIS TYPE OF FLOW WITH OVERALL RIDGING TO THE WEST AND TROUGHING EAST. WILL MOST LIKELY HAVE A FEW CLIPPER LIKE WAVES SLIDE THROUGH OUR REGION UNDER THIS TYPE OF PATTERN AND THE QUESTION IS WILL THEY BRING ANY ADDITIONAL PRECIPITATION CHANCES. BASIC ANSWER IS NO ALTHOUGH WE DO HAVE A CHANCE OF FLURRIES MENTIONED FOR WED NIGHT AND THURSDAY IN THE CURRENT FORECAST AND WILL GO AHEAD AND KEEP THEM IN GIVEN SUFFICIENT MOISTURE AND COLDER TEMPERATURES NOTED IN MODEL FORECAST SOUNDINGS. OTHERWISE WILL LEAVE THE REST OF THE FORECAST DRY ALTHOUGH SOME LIGHT PRECIPITATION NOT TOTALLY OUT OF THE QUESTION FOR FRIDAY. AS FAR AS TEMPERATURES GO...IT WILL REMAIN QUITE CHILLY WED NIGHT INTO FRIDAY MORNING AS ADDITIONAL COLD AIR SLIDES DOWN FROM THE NORTH...ALTHOUGH THE BITTER COLD AIR SHOULD REMAIN JUST NORTHEAST OF THE CWA. STOUT NORTHWEST WINDS ARE ALSO EXPECTED AGAIN FOR THURSDAY AFTERNOON AS WE SIT BETWEEN 1038 MB HIGH PRESSURE OVER MONTANA/NDAK AND LOW PRESSURE ACROSS MISSOURI AND KANSAS. FRIDAY MORNING MIGHT BE THE COLDEST DAY OF THE WEEK DEPENDING ON WHETHER HIGH PRESSURE DROPS RIGHT OVER THE TOP OF US OR SLIDES A LITTLE TO THE EAST IN WHICH CASE WE MIGHT HAVE A MORE CLOUD COVER AND LIGHT SOUTHERLY FLOW. GOING INTO THE WEEKEND HEIGHTS BEGIN TO RISE AS WESTERN RIDGE STARTS TO MOVE EAST AND AT THIS POINT APPEARS BOTH SAT AND SUNDAY SHOULD BE CLOSE TO 50 DEGREES. ANOTHER WEAK FRONT IS EXPECTED TO PUSH ACROSS SUNDAY NIGHT OR MONDAY WITH HIGH TEMPERATURES FALLING A TAD BUT STILL ABOVE SEASONAL LEVELS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...WINTER WEATHER ADVISORY UNTIL 1 AM CST WEDNESDAY FOR NEZ049-063- 064-076-077-086-087. KS...WINTER WEATHER ADVISORY UNTIL 1 AM CST WEDNESDAY FOR KSZ007. && $$ AVIATION...BRYANT SHORT TERM...HEINLEIN LONG TERM...EWALD
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1115 PM CST SUN JAN 27 2013 .UPDATE... .AVIATION... IT LOOKS LIKE THE FOG SHOULD SPREAD INTO KLBF BUT NOT MUCH FARTHER WEST. NO FOG EXPECTED FOR KVTN. THE FOG IS VERY SHALLOW WITH THE MOON VISIBLE SO BURN OFF SHOULD COMMENCE BY 15Z WITH VFR RAPIDLY DEVELOPING. THE HIGH PLAINS COLD FRONT IS THROUGH KRAP AND SHOULD CONTINUE MOVING SOUTH. BEST GUESS FOR IFR/MVFR WOULD BE 15Z ACROSS NRN NEB AND MOVING VERY SLOWLY SOUTH THROUGHOUT THE AFTN. WIDESPREAD IFR/MVFR IS EXPECTED IN SNOW AND LOW CIGS MONDAY NIGHT AS AN UPPER LEVEL DISTURBANCE LIFTS NORTHEAST THROUGH THE ROCKIES AND INTO THE CNTL/NRN PLAINS. && .PREV DISCUSSION... /ISSUED 1022 PM CST SUN JAN 27 2013/ UPDATE... DISCUSSION... SFC OBS AND SATELLITE SUGGEST DENSE FOG IS FILLING INTO HOLT AND BOYD COUNTIES SO THIS AREA HAS BEEN ADDED TO THE DENSE FOG ADVISORY. PREV DISCUSSION... /ISSUED 814 PM CST SUN JAN 27 2013/ UPDATE... DISCUSSION... DENSE FOG IS DEVELOPING ACROSS CUSTER...GARFIELD AND WHEELER COUNTIES SO A DENSE FOG ADVISORY HAS BEEN ISSUED FOR THOSE AREAS. ADDITIONAL COUNTIES WILL BE ADDED TO THE ADVISORY AS WARRANTED. PREV DISCUSSION... /ISSUED 529 PM CST SUN JAN 27 2013/ UPDATE... AVIATION... A COLD FRONT NEAR KGCC WILL DROP SOUTH TO NEAR HIGHWAY 20 OVERNIGHT AND BECOME THE FOCUS FOR IFR CIGS MONDAY AFTERNOON. THE FRONT COULD END UP FARTHER SOUTH...PERHAPS NEAR HIGHWAY 2 MONDAY MORNING SO THE FCST ACROSS NRN NEB IS UNCERTAIN. SOUTH...ALONG INTERSTATE 80 NORTH AND SOUTH TO HIGHWAY 2 AND HIGHWAY 6...FOG APPEARS LIKELY TONIGHT. MOISTURE PROFILES IN THE NAM AND RAP MODELS SUGGEST SHALLOW FOG...AND THE RAP SUGGESTS FOG NEAR KVTN ADDING TO THE FCST UNCERTAINTY ACROSS NRN NEB TONIGHT. PREV DISCUSSION... /ISSUED 355 PM CST SUN JAN 27 2013/ SYNOPSIS... SURFACE LOW PRESSURE DOMINATING THE REGION THIS AFTERNOON. SKIES HAVE TURNED MOSTLY SUNNY ACROSS WESTERN NEBRASKA WITH TEMPERATURES IN THE LOWER/MID 50S. STRATUS AND AREAS OF FOG HANGING ON IN CENTRAL AND EASTERN NEBRASKA WITH UPPER 30S TO MID 40S. SHORT TERM... TONIGHT THROUGH MONDAY NIGHT...RECENT RAINFALL FROM EARLY THIS MORNING HAS LEFT THE GROUND DAMP. RAINFALL AMOUNTS RANGED FROM 0.05 TO 0.25 INCH. DENSE FOG WHICH DEVELOPED IN THE WAKE OF THE RAIN THIS MORNING COULD AGAIN DEVELOP THIS EVENING A FEW HOURS AFTER SUNSET. MODELS DO NOT INDICATE A STRONG SIGNAL FOR FOG. HOWEVER DAMP AND COLD GROUND WITH SURFACE TEMPERATURES ABOVE FREEZING THROUGH MUCH OF THE NIGHT WITH MAINLY CLEAR SKIES IS OPTIMAL FOR RADIATION FOG. THUS...HAVE AREAS OF FOG SOUTHEASTERN AREAS WITH PATCHY FOG NORTH CENTRAL 03Z TIL 15Z MONDAY. OVERNIGHT LOWS ONLY FROM 26 TO 30 DEGREES. ANOTHER MILD DAY FOR MOST AREAS MONDAY. APPROACH OF UPPER TROUGH WILL INDUCE SURFACE CYCOLGENESIS FROM NORTHEAST COLORADO INTO NORTHWEST KANSAS. AHEAD OF A COLD FRONT...AREAS ALONG AND SOUTH OF AN OGALLALA THROUGH ONEILL LINE SHOULD WARM TO 50 DEGREES WITH NEAR 60 POSSIBLE FAR SOUTHERN COUNTIES. TO THE NORTHWEST...HIGHS TO REACH THE UPPER 30S TO UPPER 40S. AS LIFT FROM NORTHERN STREAM THROUGH BEGINS DURING THE AFTERNOON...A CHANCE FOR RAIN ACROSS THE NORTHWEST HALF. RAIN MAY MIX WITH SNOW FAR NORTHWEST BY LATE AFTERNOON. FOR MONDAY NIGHT...MODELS REMAIN CONSISTENT BUT WEAKER WITH SYNOPTIC SCALE FORCING. THE EXCEPTION IS THE NAM MODEL WHICH INDICATES FAIRLY STRONG FRONTOGENESIS CENTERED AROUND 700MB. THIS MAY LEAD TO HEAVIER SNOW BANDS OF 1 TO 2 INCHES. OVERALL SNOWFALL AMOUNTS LOOK TO RANGE FROM AN INCH OR LESS. TUESDAY AND WEDNESDAY...UPPER SYSTEM WILL TRANSLATE SOUTHEASTWARD AND WEAKEN TUESDAY. ONLY A SLIGHT CHANCE FOR LIGHT SNOW IN THE MORNING. COLDER AREA WIDE 35 TO 40 DEGREES. SURGE OF ARCTIC AIR TUESDAY NIGHT TO BRING A SLIGHT CHANCE FOR LIGHT SNOW AND FLURRIES TO THE NORTH CENTRAL. LOW TO BE 10 TO 15 ABOVE AND HIGHS WEDNESDAY FROM 18 AT ONEILL TO 35 AT IMPERIAL. LONG TERM... AMPLIFIED NORTHWEST FLOW WITH A REINFORCING SHOT OF ARCTIC AIR WILL BRING A SLIGHTLY COLDER DAY THURSDAY. HIGHS FROM 13 AT ONEILL TO 35 AT IMPERIAL. ALSO A SLIGHT CHANCE FOR SNOW ACROSS WESTERN AREAS. UPPER FLOW WILL TRANSITION TO A MORE ZONAL FLOW ALOFT WITH TEMPERATURES WARMING INTO THE 40S TO AROUND 50 FOR THE WEEKEND. DRY CONDITIONS EXPECTED FRIDAY THROUGH SUNDAY. AVIATION... SOME QUESTION ON THE FOG POTENTIAL FOR TONIGHT ACROSS CENTRAL AND SOUTHWEST NEBRASKA...AS SOME MODEL DATA NOT INDICATING THE FOG. FEEL THOUGH THAT WITH THE RECENT RAINFALL AND LIGHT WINDS TONIGHT...AT LEAST GROUND FOG WILL DEVELOP. FEEL THE BEST COURSE OF ACTION IS TO CONTINUE BRINGING THE VISIBILITY DOWN TO IFR AT KLBF DURING THE EVENING AND CONTINUE THROUGH EARLY MONDAY MORNING. DUE TO UNCERTAINTY...WILL NOT GO WITH ANY LIFR OR VLIFR AT THIS TIME...BUT SOME POTENTIAL IS THERE. ACROSS NORTH CENTRAL NEBRASKA...INCLUDING THE KVTN TERMINAL...STRATUS MAY MOVE SOUTH OUT OF SOUTH DAKOTA MONDAY MORNING. HERE TOO CONFIDENCE IS LOW...AND WILL NOT INTRODUCE INTO THE TAF AT THIS TIME. SFC WINDS WILL REMAIN LIGHT THOUGH TONIGHT. && .LBF WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVISORY UNTIL 10 AM CST MONDAY FOR NEZ007-010-028-029- 038. && $$ SHORT TERM/EXTENDED...MASEK AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1022 PM CST SUN JAN 27 2013 .UPDATE... .DISCUSSION... SFC OBS AND SATELLITE SUGGEST DENSE FOG IS FILLING INTO HOLT AND BOYD COUNTIES SO THIS AREA HAS BEEN ADDED TO THE DENSE FOG ADVISORY. && .PREV DISCUSSION... /ISSUED 814 PM CST SUN JAN 27 2013/ UPDATE... DISCUSSION... DENSE FOG IS DEVELOPING ACROSS CUSTER...GARFIELD AND WHEELER COUNTIES SO A DENSE FOG ADVISORY HAS BEEN ISSUED FOR THOSE AREAS. ADDITIONAL COUNTIES WILL BE ADDED TO THE ADVISORY AS WARRANTED. PREV DISCUSSION... /ISSUED 529 PM CST SUN JAN 27 2013/ UPDATE... AVIATION... A COLD FRONT NEAR KGCC WILL DROP SOUTH TO NEAR HIGHWAY 20 OVERNIGHT AND BECOME THE FOCUS FOR IFR CIGS MONDAY AFTERNOON. THE FRONT COULD END UP FARTHER SOUTH...PERHAPS NEAR HIGHWAY 2 MONDAY MORNING SO THE FCST ACROSS NRN NEB IS UNCERTAIN. SOUTH...ALONG INTERSTATE 80 NORTH AND SOUTH TO HIGHWAY 2 AND HIGHWAY 6...FOG APPEARS LIKELY TONIGHT. MOISTURE PROFILES IN THE NAM AND RAP MODELS SUGGEST SHALLOW FOG...AND THE RAP SUGGESTS FOG NEAR KVTN ADDING TO THE FCST UNCERTAINTY ACROSS NRN NEB TONIGHT. PREV DISCUSSION... /ISSUED 355 PM CST SUN JAN 27 2013/ SYNOPSIS... SURFACE LOW PRESSURE DOMINATING THE REGION THIS AFTERNOON. SKIES HAVE TURNED MOSTLY SUNNY ACROSS WESTERN NEBRASKA WITH TEMPERATURES IN THE LOWER/MID 50S. STRATUS AND AREAS OF FOG HANGING ON IN CENTRAL AND EASTERN NEBRASKA WITH UPPER 30S TO MID 40S. SHORT TERM... TONIGHT THROUGH MONDAY NIGHT...RECENT RAINFALL FROM EARLY THIS MORNING HAS LEFT THE GROUND DAMP. RAINFALL AMOUNTS RANGED FROM 0.05 TO 0.25 INCH. DENSE FOG WHICH DEVELOPED IN THE WAKE OF THE RAIN THIS MORNING COULD AGAIN DEVELOP THIS EVENING A FEW HOURS AFTER SUNSET. MODELS DO NOT INDICATE A STRONG SIGNAL FOR FOG. HOWEVER DAMP AND COLD GROUND WITH SURFACE TEMPERATURES ABOVE FREEZING THROUGH MUCH OF THE NIGHT WITH MAINLY CLEAR SKIES IS OPTIMAL FOR RADIATION FOG. THUS...HAVE AREAS OF FOG SOUTHEASTERN AREAS WITH PATCHY FOG NORTH CENTRAL 03Z TIL 15Z MONDAY. OVERNIGHT LOWS ONLY FROM 26 TO 30 DEGREES. ANOTHER MILD DAY FOR MOST AREAS MONDAY. APPROACH OF UPPER TROUGH WILL INDUCE SURFACE CYCOLGENESIS FROM NORTHEAST COLORADO INTO NORTHWEST KANSAS. AHEAD OF A COLD FRONT...AREAS ALONG AND SOUTH OF AN OGALLALA THROUGH ONEILL LINE SHOULD WARM TO 50 DEGREES WITH NEAR 60 POSSIBLE FAR SOUTHERN COUNTIES. TO THE NORTHWEST...HIGHS TO REACH THE UPPER 30S TO UPPER 40S. AS LIFT FROM NORTHERN STREAM THROUGH BEGINS DURING THE AFTERNOON...A CHANCE FOR RAIN ACROSS THE NORTHWEST HALF. RAIN MAY MIX WITH SNOW FAR NORTHWEST BY LATE AFTERNOON. FOR MONDAY NIGHT...MODELS REMAIN CONSISTENT BUT WEAKER WITH SYNOPTIC SCALE FORCING. THE EXCEPTION IS THE NAM MODEL WHICH INDICATES FAIRLY STRONG FRONTOGENESIS CENTERED AROUND 700MB. THIS MAY LEAD TO HEAVIER SNOW BANDS OF 1 TO 2 INCHES. OVERALL SNOWFALL AMOUNTS LOOK TO RANGE FROM AN INCH OR LESS. TUESDAY AND WEDNESDAY...UPPER SYSTEM WILL TRANSLATE SOUTHEASTWARD AND WEAKEN TUESDAY. ONLY A SLIGHT CHANCE FOR LIGHT SNOW IN THE MORNING. COLDER AREA WIDE 35 TO 40 DEGREES. SURGE OF ARCTIC AIR TUESDAY NIGHT TO BRING A SLIGHT CHANCE FOR LIGHT SNOW AND FLURRIES TO THE NORTH CENTRAL. LOW TO BE 10 TO 15 ABOVE AND HIGHS WEDNESDAY FROM 18 AT ONEILL TO 35 AT IMPERIAL. LONG TERM... AMPLIFIED NORTHWEST FLOW WITH A REINFORCING SHOT OF ARCTIC AIR WILL BRING A SLIGHTLY COLDER DAY THURSDAY. HIGHS FROM 13 AT ONEILL TO 35 AT IMPERIAL. ALSO A SLIGHT CHANCE FOR SNOW ACROSS WESTERN AREAS. UPPER FLOW WILL TRANSITION TO A MORE ZONAL FLOW ALOFT WITH TEMPERATURES WARMING INTO THE 40S TO AROUND 50 FOR THE WEEKEND. DRY CONDITIONS EXPECTED FRIDAY THROUGH SUNDAY. AVIATION... SOME QUESTION ON THE FOG POTENTIAL FOR TONIGHT ACROSS CENTRAL AND SOUTHWEST NEBRASKA...AS SOME MODEL DATA NOT INDICATING THE FOG. FEEL THOUGH THAT WITH THE RECENT RAINFALL AND LIGHT WINDS TONIGHT...AT LEAST GROUND FOG WILL DEVELOP. FEEL THE BEST COURSE OF ACTION IS TO CONTINUE BRINGING THE VISIBILITY DOWN TO IFR AT KLBF DURING THE EVENING AND CONTINUE THROUGH EARLY MONDAY MORNING. DUE TO UNCERTAINTY...WILL NOT GO WITH ANY LIFR OR VLIFR AT THIS TIME...BUT SOME POTENTIAL IS THERE. ACROSS NORTH CENTRAL NEBRASKA...INCLUDING THE KVTN TERMINAL...STRATUS MAY MOVE SOUTH OUT OF SOUTH DAKOTA MONDAY MORNING. HERE TOO CONFIDENCE IS LOW...AND WILL NOT INTRODUCE INTO THE TAF AT THIS TIME. SFC WINDS WILL REMAIN LIGHT THOUGH TONIGHT. && .LBF WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVISORY UNTIL 10 AM CST MONDAY FOR NEZ007-010-028-029- 038. && $$ SHORT TERM/EXTENDED...CDC AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BUFFALO NY
929 PM EST TUE JAN 29 2013 .SYNOPSIS... THERE WILL BE A SOUTHERLY FLOW OF MILD AIR ACROSS THE REGION TONIGHT AND TOMORROW WITH PERIODS OF RAIN...SOME OF WHICH MAY FALL AS FREEZING RAIN EARLY ACROSS THE NORTH COUNTRY. A COLD FRONT WILL SWEEP ACROSS THE REGION LATE TOMORROW AND TOMORROW NIGHT WITH GUSTY WINDS...RAIN AND SHARPLY FALLING TEMPERATURES. BEHIND THIS COLD FRONT EXPECT ACCUMULATING LAKE EFFECT SNOW IN THE TRADITIONAL SNOWBELTS EAST AND SOUTHEAST OF THE LAKES FOR THE END OF THE WEEK. && .NEAR TERM /THROUGH WEDNESDAY/... THROUGH THIS EVENING...AN AREA OF SHOWERS IS MOVING ACROSS THE REGION...TRACKING TO THE EAST-NORTHEAST. THERE HAVE BEEN A FEW LIGHTNING STRIKES WITH THIS...WITH A RUMBLE OF THUNDER STILL POSSIBLE THIS EVENING. THE HRRR MODEL HAS A GOOD HANDLE ON THIS...WITH THE STEADIEST SHOWERS LIKELY TO MOVE ACROSS THE REGION DURING THE EVENING HOURS...EXITING TO THE NORTH AROUND MIDNIGHT. THUS FAR...THE NAM/RGEM HAVE BEEN OVERDONE IN QPF EAST OF LAKE ONTARIO...OTHERWISE THESE MODELS ARE IN GENERAL AGREEMENT WITH THE HRRR AND RADAR TRENDS. WILL CONTINUE WITH A PERIOD OF CATEGORICAL POPS FOR MOST LOCATIONS...BUT SPEED UP THE EXIT A BIT BASED ON THE ABOVE DISCUSSION. TEMPERATURES HAVE RISEN INTO THE LOWER 50S ACROSS MUCH OF WESTERN NEW YORK AS WARMER TEMPERATURES ALOFT MIX DOWN...AND HAVE STARTED TO WARM EAST OF LAKE ONTARIO. BY NOW...EXPECT ALL AREAS ARE ABOVE FREEZING...WHICH ALLOWS US TO DROP THE WINTER WEATHER ADVISORY. THE COMBINATION OF WARM DEW POINTS AND LINGERING SNOW PACK HAS RESULTED IN AREAS OF FOG ACROSS THE REGION. VISIBILITY HAS IMPROVED ENOUGH TO END THE DENSE FOG ADVISORY ACROSS THE SOUTHERN TIER...HOWEVER FOG SHOULD INCREASE EAST OF LAKE ONTARIO AS DEW POINTS RISE. AS THIS UPPER LEVEL SHORTWAVE NEARS THE SOUTHERN PLAINS LOW...THE SURFACE LOW WILL DEEPEN AS IT NEARS THE CENTRAL GREAT LAKES REGION TOMORROW MORNING. A 75 TO 80 KNOT LOW LEVEL JET 3K FEET OFF THE GROUND AHEAD OF THIS SURFACE LOW WILL REACH INTO THE SOUTHWESTERN PORTIONS OF OUR CWA AFTER MIDNIGHT...AND SLIGHTLY WEAKER FARTHER EASTWARD. THOUGH WARM AIR ADVECTION SHOULD PREVENT THESE STRONGER WIND GUSTS FROM MIXING DOWN...A SUSTAINED WIND MAY REACH AS HIGH AS 25 TO 30 KNOTS ACROSS MAINLY THE HIGHER ELEVATIONS OF THE SOUTHERN TIER. WILL HOIST A WIND ADVISORY FOR THIS REASON...AND CONTINUE THE ADVISORY INTO THURSDAY. AS THE LOW LEVEL JET PASSES EASTWARD LATER WEDNESDAY THERE MAY BE A TIME OF SLIGHTLY WEAKER WINDS. WEDNESDAY THE SURFACE LOW OVER THE CENTRAL GREAT LAKES WILL CONTINUE TO DEEPEN AS IT PASSES JUST TO THE NORTH OF THE REGION. WITH THE INCREASING PRESSURE GRADIENT GUSTY WINDS WILL CONTINUE THROUGH THE DAY WEDNESDAY. THIS DEEPENING SURFACE LOW WILL DRAG A COLD FRONT TO NEAR WESTERN NEW YORK BY 00Z...HOWEVER BOTH THE NAM AND GFS ARE SUGGESTING A SURFACE TROUGH AHEAD OF THE COLD FRONT MAY BRING A LINE OF SHOWERS INTO THE REGION LATE MORNING TOWARDS THE WEST AND THEN EASTWARD ACROSS THE CWA IN THE AFTERNOON. WHILE INSTABILITY WILL REMAIN MARGINAL...THE UPPER LEVEL DYNAMICS OF A POTENT SHORTWAVE AND STRONG HEIGHT FALLS WILL LIKELY LEAD TO THE POSSIBILITY OF THUNDER WITHIN A POTENTIAL CONVECTIVE SQUALL LINE CROSSING THE REGION. TEMPERATURES TONIGHT WILL REMAIN STEADY TO SLIGHTLY RISING THROUGH THE NIGHT. HIGHS TOMORROW BE NEAR RECORD LEVELS WITH HIGHS IN THE MID 50S...TO LOWER 60S. RECORD HIGHS TOMORROW INCLUDE....BUFFALO 56 (1916)...ROCHESTER 55 (1974)...AND WATERTOWN 52 (2006). && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... SHARP COLD FRONT IS STILL EXPECTED TRACK FROM WEST TO EAST ACROSS THE AREA DURING THE EVENING HOURS...WITH PROFILES NOT SUPPORTING SNOW ACROSS MOST AREAS UNTIL AFTER MIDNIGHT. THEREFORE...WE CONTINUE TO EXPECTED A BAND OF SHOWERS AND EMBEDDED THUNDERSTORMS TO CROSS THE AREA ALONG AND AHEAD OF THE FRONT DURING THE EVENING. THERE IS SOME CONCERN FOR A BAND OF ENHANCED WINDS IF THE CONVECTIVE LINE CAN ORGANIZE SUFFICIENTLY. FIRST CONCERN BEHIND THE FRONT WILL BE THE POTENTIAL FOR ADVISORY OR NEAR WARNING LEVEL WINDS. IMPRESSIVELY STRONG COLD ADVECTION WILL ALLOW FOR DEEP MIXING WITH WINDS GUSTS OF 50 TO 55 MPH POSSIBLE WEDNESDAY NIGHT THROUGH A GOOD PART OF THURSDAY. A WIND ADVISORY WILL BE ISSUED FOR THE ENTIRE AREA TO ADDRESS THIS HIGH WIND POTENTIAL. TEMPERATURES WILL FALL SHARPLY IN WAKE OF THE FRONT WITH 50S IN THE EVENING DROPPING INTO THE 20S BY THURSDAY MORNING. A SECONDARY UPPER TROUGH WILL DIG INTO THE GREAT LAKES THURSDAY THAT WILL PROVIDE AN INITIAL LAKE EFFECT SETUP AS THE COLD AIR GRADUALLY DEEPENS. DEPTH OF INSTABILITY NOT OVERLY IMPRESSIVE INITIALLY AND THINK ACCUMULATIONS WILL BE LIMITED TO JUST A COUPLE INCHES...ACROSS PRIMARILY THE CHAUTAUQUA RIDGE AS WELL AS THE TUG HILL. THE COLD AIR WILL CONTINUE TO DEEPEN THURSDAY AFTERNOON AND THURSDAY NIGHT...WITH 850 MB TEMPERATURES DROPPING TO NEAR -20C BY FRIDAY MORNING. INSPECTION OF NAM BUFR SOUNDINGS SHOWING THAT THE LAKE RESPONSE WILL BE ON THE UPTICK AFTER 18Z THURSDAY AS THE PASSING OF A SHORTWAVE SIGNIFICANTLY WEAKENS THE INVERSION AND ALLOWS EQUILIBRIUM HEIGHTS TO CLIMB TO AROUND 12K FEET. THERE ARE SEVERAL FACTORS WHICH POINT TO THE POTENTIAL FOR ANOTHER SIGNIFICANT LAKE EFFECT EVENT FOR THIS PERIOD. BESIDES THE EXCELLENT OVER-LAKE INSTABILITY WITH LAKE INDUCED CAPES CLIMBING TO AROUND 700 J/KG...AMBIENT MOISTURE WILL BE MORE THAN ADEQUATE WITH THE PASSING WAVE. ALTHOUGH THE DENDRITIC GROWTH ZONE WILL BE RELATIVELY LOW IN THE COLD AIRMASS...WE SHOULD STILL BE ABLE TO GET SOME DECENT SNOW RATIOS. THE BEST POTENTIAL FOR SIGNIFICANT ACCUMULATING LAKE SNOWS WILL BE IN FAVORED WESTERLY FETCH AREAS OF THE SOUTHERN TIER AND EAST OF LAKE ONTARIO. LAKE EFFECT SNOW WATCHES WILL BE ISSUED FOR THESE AREAS. && .LONG TERM /SATURDAY THROUGH TUESDAY/... THE LATEST MEDIUM RANGE MODELS AND ENSEMBLE FORECASTS CONTINUING TO SUGGEST THAT THE COLD AIR ADVECTIVE PATTERN WILL CONTINUE THROUGH THE WEEKEND...AS THE MEAN TROUGH REMAINS OVER THE GREAT LAKES AND NEW ENGLAND. THIS WILL RESULT IN TEMPERATURES FALLING BACK TO BELOW NORMAL LEVELS. PARAMETERS FOR CONTINUED ACCUMULATING LAKE EFFECT SNOWS CONTINUE TO LOOK GOOD AS 850 MB TEMPERATURES REMAINING AROUND -20C...COMBINED WITH EXCELLENT 850 MB TO 700 MB MOISTURE. ABOUT THE ONLY NEGATIVE WILL BE THE LOWER THAN IDEAL INVERSION HEIGHTS WHICH WILL BE GENERALLY FALL BELOW 7K FEET AND SOME LOSS OF DENDRITIC GROWTH DEPTH AS MUCH OF THE SATURATED LAYER FALLS BELOW -18C. THE PASSAGE OF SEVERAL SHORTWAVES WILL KEEP WINDS LESS THAN STEADY STATE WITH LAKE EFFECT BANDS IMPACTING MULTIPLE AREAS OVER THE WEEKEND...WITH SOME AREAS STILL HAVING THE POTENTIAL FOR SIGNIFICANT SNOWS. THE UPPER TROUGH LOOKS TO RETREAT BACK UP INTO NORTHEAST CANADA BY EARLY NEXT WEEK...ALLOWING FOR A MODERATION IN TEMPERATURES AND LIKELY AN END TO THE LAKE EFFECT SNOWS. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... AN AREA OF STEADY SHOWERS WILL MOVE FROM SW-NE THROUGH 06Z...FIRST IMPACTING WESTERN TAF SITES. THIS AREA OF ELEVATED CONVECTION HAS A FEW EMBEDDED THUNDERSTORMS...WHICH MAY BRIEFLY IMPACT BUF/IAG BEFORE 03Z. THE MAJORITY OF THE NIGHT SHOULD BE VFR FOR BUF/IAG/ROC...WITH ONLY LINGERING MVFR CIGS AND LOWER VSBY IN SHOWERS THIS EVENING. THE 00Z BUFFALO SOUNDING SHOWS A FAIRLY MIXED BOUNDARY LAYER...WITH CIGS LIKELY TO REMAIN ABOVE THIS. EXPECT LOWER CONDITIONS AT JHW/ART...WHERE THERE IS STILL SOME SNOWPACK TO ENHANCE LOW LEVEL MOISTURE AND FOG DEVELOPMENT. EXPECT A GENERAL IMPROVING TREND AT JHW AS WINDS PICK UP...AND DETERIORATING CONDITIONS AT ART GIVEN THE DEEP SNOW PACK AND INCREASING DEW POINTS. IN EACH CASE...FORECAST CONFIDENCE IS LOW...SINCE THE MIXING OF WINDS WILL PLAY A KEY ROLE. OTHERWISE...LLWS WILL BE A LINGERING CONCERN FOR THE TAFS THROUGHOUT THE PERIOD. A LOW LEVEL JET WILL PRODUCE WINDS TO 65 KNOTS AT 1500 FEET...WITH THESE EXPECTED TO STRUGGLE TO MIX TO THE SURFACE. ON WEDNESDAY...A LINE OF SHOWERS WILL MOVE ACROSS...WITH AGAIN A RUMBLE OF THUNDER POSSIBLE. VFR/MVFR CONDITIONS ARE LIKELY...EXCEPT FOR LOCALLY HEAVY SHOWERS. OUTLOOK... THURSDAY THROUGH SATURDAY...MVFR WITH LOCALIZED IFR IN LAKE EFFECT SNOW SHOWERS EAST OF THE LAKES. SUNDAY...MAINLY VFR WITH MVFR IN LOCALIZED LAKE EFFECT SNOW SHOWERS. && .MARINE... WINDS WILL STRENGTHEN MORE TONIGHT AND WEDNESDAY AS THE PRESSURE GRADIENT INCREASES AHEAD OF THE ADVANCING LOW AND ITS ASSOCIATED COLD FRONT. SMALL CRAFT ADVISORIES HAVE BEEN ISSUES BEGINNING TONIGHT INTO WEDNESDAY THEN GALE WATCHES TAKE OVER WITH GALE FORCE WINDS POSSIBLE WEDNESDAY NIGHT AHEAD AND ALONG THE COLD FRONTAL PASSAGE. && .HYDROLOGY... THERE APPEARS TO BE SOME MINOR ICE JAMMING ON SOME OF THE CREEKS...WITH HYDROGRAPHS SUGGESTING THERE IS OR HAS BEEN SOME ICE FLOW ON THE CAYUGA CREEK...CAZENOVIA CREEK...BUFFALO CREEK...AND CATTARAUGUS CREEK...AS WELL AS A SPOTTER REPORT OF ICE FLOWS ON THE CONEWANGO. IN ALL OF THESE CASES...EXPECT THE ICE IS RATHER THIN...WITH ANY JAMS LIKELY TO BE RELATIVELY SHORT LIVED. THIS SAID...WILL CONTINUE TO MONITOR THESE CREEKS...AS IT IS POSSIBLE THERE WILL BE TEMPORARY AND MINOR ICE JAM FLOODING IN A FEW SPOTS OVERNIGHT. THIS SHOULD REMOVE AND MELT MUCH OF THE ICE WHICH HAS FORMED OVER THE PAST PERIOD OF COLD WEATHER. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...LAKE EFFECT SNOW WATCH FROM THURSDAY AFTERNOON THROUGH LATE FRIDAY NIGHT FOR NYZ006>008-012-019-020-085. WIND ADVISORY FROM 1 AM WEDNESDAY TO 1 PM EST THURSDAY FOR NYZ012-019-020-085. WIND ADVISORY FROM 6 PM WEDNESDAY TO 1 PM EST THURSDAY FOR NYZ001>008-010-011-013-014-021. MARINE...GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY MORNING FOR LEZ020-040-041. SMALL CRAFT ADVISORY UNTIL 7 PM EST WEDNESDAY FOR LEZ020- 040-041. GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY AFTERNOON FOR LOZ030-042>045-062>065. SMALL CRAFT ADVISORY FROM 1 AM TO 9 PM EST WEDNESDAY FOR LOZ030. SMALL CRAFT ADVISORY FROM 4 AM TO 9 PM EST WEDNESDAY FOR LOZ042>045. && $$ SYNOPSIS...THOMAS NEAR TERM...APFFEL/THOMAS SHORT TERM...TMA LONG TERM...TMA AVIATION...APFFEL/TJP MARINE...APFFEL/THOMAS HYDROLOGY...APFFEL
AREA FORECAST DISCUSSION
NWS BUFFALO NY
740 PM EST TUE JAN 29 2013 .SYNOPSIS... THERE WILL BE A SOUTHERLY FLOW OF MILD AIR ACROSS THE REGION TONIGHT AND TOMORROW WITH PERIODS OF RAIN...SOME OF WHICH MAY FALL AS FREEZING RAIN EARLY ACROSS THE NORTH COUNTRY. A COLD FRONT WILL SWEEP ACROSS THE REGION LATE TOMORROW AND TOMORROW NIGHT WITH GUSTY WINDS...RAIN AND SHARPLY FALLING TEMPERATURES. BEHIND THIS COLD FRONT EXPECT ACCUMULATING LAKE EFFECT SNOW IN THE TRADITIONAL SNOWBELTS EAST AND SOUTHEAST OF THE LAKES FOR THE END OF THE WEEK. && .NEAR TERM /THROUGH WEDNESDAY/... THROUGH EARLY EVENING...THE MOST SIGNIFICANT AREA OF SHOWERS IS JUST NORTH OF LAKE ERIE...TRACKING TO THE EAST-NORTHEAST. THERE HAVE BEEN A FEW LIGHTNING STRIKES WITH THIS...WITH A RUMBLE OF THUNDER POSSIBLE ACROSS THE NIAGARA FRONTIER DURING THE EVENING HOURS. THE HRRR MODEL HAS A GOOD HANDLE ON THIS...WITH THE STEADIEST SHOWERS LIKELY TO MOVE ACROSS THE REGION DURING THE EVENING HOURS...EXITING TO THE NORTH AROUND MIDNIGHT. THUS FAR...THE NAM/RGEM HAVE BEEN OVERDONE IN QPF EAST OF LAKE ONTARIO...OTHERWISE THESE MODELS ARE IN GENERAL AGREEMENT WITH THE HRRR AND RADAR TRENDS. WILL CONTINUE WITH A PERIOD OF CATEGORICAL POPS FOR MOST LOCATIONS...BUT SPEED UP THE EXIT A BIT BASED ON THE ABOVE DISCUSSION. TEMPERATURES HAVE RISEN INTO THE LOWER 50S ACROSS MUCH OF WESTERN NEW YORK AS WARMER TEMPERATURES ALOFT MIX DOWN. NORTHEAST WINDS THROUGH THE SAINT LAWRENCE VALLEY FROM A SURFACE HIGH OVER SOUTHEASTERN QUEBEC HAVE MAINTAINED A SHALLOW LAYER OF SUBFREEZING TEMPERATURES ACROSS THE SAINT LAWRENCE VALLEY AND SHELTERED PORTIONS OF THE NORTH COUNTRY. WHILE THE MAJORITY OF JEFFERSON AND LEWIS COUNTIES ARE ABOVE FREEZING AS OF EARLY EVENING...THE LIGHT NORTHEAST FLOW IS TRAPPING SUB-FREEZING AIR IN A FEW SPOTS. ALSO...THE GROUND WILL LIKELY LAG IN WARMING TO STILL CREATE THE POTENTIAL FOR ICY SPOTS IN FALLING PRECIPITATION. FOR THESE REASONS...WILL MAINTAIN THE WINTER WEATHER ADVISORY FOR NOW...WITH A RAPID RISE IN TEMPERATURES LIKELY LATER THIS EVENING EAST OF LAKE ONTARIO. THE COMBINATION OF WARM DEW POINTS AND LINGERING SNOW PACK HAS RESULTED IN AREAS OF FOG ACROSS THE REGION. VISIBILITY HAS IMPROVED ENOUGH TO END THE DENSE FOG ADVISORY ACROSS THE SOUTHERN TIER...HOWEVER FOG SHOULD INCREASE EAST OF LAKE ONTARIO AS DEW POINTS RISE. AS THIS UPPER LEVEL SHORTWAVE NEARS THE SOUTHERN PLAINS LOW...THE SURFACE LOW WILL DEEPEN AS IT NEARS THE CENTRAL GREAT LAKES REGION TOMORROW MORNING. A 75 TO 80 KNOT LOW LEVEL JET 3K FEET OFF THE GROUND AHEAD OF THIS SURFACE LOW WILL REACH INTO THE SOUTHWESTERN PORTIONS OF OUR CWA AFTER MIDNIGHT...AND SLIGHTLY WEAKER FARTHER EASTWARD. THOUGH WARM AIR ADVECTION SHOULD PREVENT THESE STRONGER WIND GUSTS FROM MIXING DOWN...A SUSTAINED WIND MAY REACH AS HIGH AS 25 TO 30 KNOTS ACROSS MAINLY THE HIGHER ELEVATIONS OF THE SOUTHERN TIER. WILL HOIST A WIND ADVISORY FOR THIS REASON...AND CONTINUE THE ADVISORY INTO THURSDAY. AS THE LOW LEVEL JET PASSES EASTWARD LATER WEDNESDAY THERE MAY BE A TIME OF SLIGHTLY WEAKER WINDS. WEDNESDAY THE SURFACE LOW OVER THE CENTRAL GREAT LAKES WILL CONTINUE TO DEEPEN AS IT PASSES JUST TO THE NORTH OF THE REGION. WITH THE INCREASING PRESSURE GRADIENT GUSTY WINDS WILL CONTINUE THROUGH THE DAY WEDNESDAY. THIS DEEPENING SURFACE LOW WILL DRAG A COLD FRONT TO NEAR WESTERN NEW YORK BY 00Z...HOWEVER BOTH THE NAM AND GFS ARE SUGGESTING A SURFACE TROUGH AHEAD OF THE COLD FRONT MAY BRING A LINE OF SHOWERS INTO THE REGION LATE MORNING TOWARDS THE WEST AND THEN EASTWARD ACROSS THE CWA IN THE AFTERNOON. WHILE INSTABILITY WILL REMAIN MARGINAL...THE UPPER LEVEL DYNAMICS OF A POTENT SHORTWAVE AND STRONG HEIGHT FALLS WILL LIKELY LEAD TO THE POSSIBILITY OF THUNDER WITHIN A POTENTIAL CONVECTIVE SQUALL LINE CROSSING THE REGION. TEMPERATURES TONIGHT WILL REMAIN STEADY TO SLIGHTLY RISING THROUGH THE NIGHT. HIGHS TOMORROW BE NEAR RECORD LEVELS WITH HIGHS IN THE MID 50S...TO LOWER 60S. RECORD HIGHS TOMORROW INCLUDE....BUFFALO 56 (1916)...ROCHESTER 55 (1974)...AND WATERTOWN 52 (2006). && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... SHARP COLD FRONT IS STILL EXPECTED TRACK FROM WEST TO EAST ACROSS THE AREA DURING THE EVENING HOURS...WITH PROFILES NOT SUPPORTING SNOW ACROSS MOST AREAS UNTIL AFTER MIDNIGHT. THEREFORE...WE CONTINUE TO EXPECTED A BAND OF SHOWERS AND EMBEDDED THUNDERSTORMS TO CROSS THE AREA ALONG AND AHEAD OF THE FRONT DURING THE EVENING. THERE IS SOME CONCERN FOR A BAND OF ENHANCED WINDS IF THE CONVECTIVE LINE CAN ORGANIZE SUFFICIENTLY. FIRST CONCERN BEHIND THE FRONT WILL BE THE POTENTIAL FOR ADVISORY OR NEAR WARNING LEVEL WINDS. IMPRESSIVELY STRONG COLD ADVECTION WILL ALLOW FOR DEEP MIXING WITH WINDS GUSTS OF 50 TO 55 MPH POSSIBLE WEDNESDAY NIGHT THROUGH A GOOD PART OF THURSDAY. A WIND ADVISORY WILL BE ISSUED FOR THE ENTIRE AREA TO ADDRESS THIS HIGH WIND POTENTIAL. TEMPERATURES WILL FALL SHARPLY IN WAKE OF THE FRONT WITH 50S IN THE EVENING DROPPING INTO THE 20S BY THURSDAY MORNING. A SECONDARY UPPER TROUGH WILL DIG INTO THE GREAT LAKES THURSDAY THAT WILL PROVIDE AN INITIAL LAKE EFFECT SETUP AS THE COLD AIR GRADUALLY DEEPENS. DEPTH OF INSTABILITY NOT OVERLY IMPRESSIVE INITIALLY AND THINK ACCUMULATIONS WILL BE LIMITED TO JUST A COUPLE INCHES...ACROSS PRIMARILY THE CHAUTAUQUA RIDGE AS WELL AS THE TUG HILL. THE COLD AIR WILL CONTINUE TO DEEPEN THURSDAY AFTERNOON AND THURSDAY NIGHT...WITH 850 MB TEMPERATURES DROPPING TO NEAR -20C BY FRIDAY MORNING. INSPECTION OF NAM BUFR SOUNDINGS SHOWING THAT THE LAKE RESPONSE WILL BE ON THE UPTICK AFTER 18Z THURSDAY AS THE PASSING OF A SHORTWAVE SIGNIFICANTLY WEAKENS THE INVERSION AND ALLOWS EQUILIBRIUM HEIGHTS TO CLIMB TO AROUND 12K FEET. THERE ARE SEVERAL FACTORS WHICH POINT TO THE POTENTIAL FOR ANOTHER SIGNIFICANT LAKE EFFECT EVENT FOR THIS PERIOD. BESIDES THE EXCELLENT OVER-LAKE INSTABILITY WITH LAKE INDUCED CAPES CLIMBING TO AROUND 700 J/KG...AMBIENT MOISTURE WILL BE MORE THAN ADEQUATE WITH THE PASSING WAVE. ALTHOUGH THE DENDRITIC GROWTH ZONE WILL BE RELATIVELY LOW IN THE COLD AIRMASS...WE SHOULD STILL BE ABLE TO GET SOME DECENT SNOW RATIOS. THE BEST POTENTIAL FOR SIGNIFICANT ACCUMULATING LAKE SNOWS WILL BE IN FAVORED WESTERLY FETCH AREAS OF THE SOUTHERN TIER AND EAST OF LAKE ONTARIO. LAKE EFFECT SNOW WATCHES WILL BE ISSUED FOR THESE AREAS. && .LONG TERM /SATURDAY THROUGH TUESDAY/... THE LATEST MEDIUM RANGE MODELS AND ENSEMBLE FORECASTS CONTINUING TO SUGGEST THAT THE COLD AIR ADVECTIVE PATTERN WILL CONTINUE THROUGH THE WEEKEND...AS THE MEAN TROUGH REMAINS OVER THE GREAT LAKES AND NEW ENGLAND. THIS WILL RESULT IN TEMPERATURES FALLING BACK TO BELOW NORMAL LEVELS. PARAMETERS FOR CONTINUED ACCUMULATING LAKE EFFECT SNOWS CONTINUE TO LOOK GOOD AS 850 MB TEMPERATURES REMAINING AROUND -20C...COMBINED WITH EXCELLENT 850 MB TO 700 MB MOISTURE. ABOUT THE ONLY NEGATIVE WILL BE THE LOWER THAN IDEAL INVERSION HEIGHTS WHICH WILL BE GENERALLY FALL BELOW 7K FEET AND SOME LOSS OF DENDRITIC GROWTH DEPTH AS MUCH OF THE SATURATED LAYER FALLS BELOW -18C. THE PASSAGE OF SEVERAL SHORTWAVES WILL KEEP WINDS LESS THAN STEADY STATE WITH LAKE EFFECT BANDS IMPACTING MULTIPLE AREAS OVER THE WEEKEND...WITH SOME AREAS STILL HAVING THE POTENTIAL FOR SIGNIFICANT SNOWS. THE UPPER TROUGH LOOKS TO RETREAT BACK UP INTO NORTHEAST CANADA BY EARLY NEXT WEEK...ALLOWING FOR A MODERATION IN TEMPERATURES AND LIKELY AN END TO THE LAKE EFFECT SNOWS. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... AN AREA OF STEADY SHOWERS WILL MOVE FROM SW-NE THROUGH 06Z...FIRST IMPACTING WESTERN TAF SITES. THIS AREA OF ELEVATED CONVECTION HAS A FEW EMBEDDED THUNDERSTORMS...WHICH MAY BRIEFLY IMPACT BUF/IAG BEFORE 03Z. THE MAJORITY OF THE NIGHT SHOULD BE VFR FOR BUF/IAG/ROC...WITH ONLY LINGERING MVFR CIGS AND LOWER VSBY IN SHOWERS THIS EVENING. THE 00Z BUFFALO SOUNDING SHOWS A FAIRLY MIXED BOUNDARY LAYER...WITH CIGS LIKELY TO REMAIN ABOVE THIS. EXPECT LOWER CONDITIONS AT JHW/ART...WHERE THERE IS STILL SOME SNOWPACK TO ENHANCE LOW LEVEL MOISTURE AND FOG DEVELOPMENT. EXPECT A GENERAL IMPROVING TREND AT JHW AS WINDS PICK UP...AND DETERIORATING CONDITIONS AT ART GIVEN THE DEEP SNOW PACK AND INCREASING DEW POINTS. IN EACH CASE...FORECAST CONFIDENCE IS LOW...SINCE THE MIXING OF WINDS WILL PLAY A KEY ROLE. OTHERWISE...LLWS WILL BE A LINGERING CONCERN FOR THE TAFS THROUGHOUT THE PERIOD. A LOW LEVEL JET WILL PRODUCE WINDS TO 65 KNOTS AT 1500 FEET...WITH THESE EXPECTED TO STRUGGLE TO MIX TO THE SURFACE. ON WEDNESDAY...A LINE OF SHOWERS WILL MOVE ACROSS...WITH AGAIN A RUMBLE OF THUNDER POSSIBLE. VFR/MVFR CONDITIONS ARE LIKELY...EXCEPT FOR LOCALLY HEAVY SHOWERS. OUTLOOK... THURSDAY THROUGH SATURDAY...MVFR WITH LOCALIZED IFR IN LAKE EFFECT SNOW SHOWERS EAST OF THE LAKES. SUNDAY...MAINLY VFR WITH MVFR IN LOCALIZED LAKE EFFECT SNOW SHOWERS. && .MARINE... SOME DENSE FOG WILL BE FOUND OVER THE LAKES THIS MORNING WITH THE VERY MOIST AIRMASS THAT HAS SHIFTED OVER THE LOWER LAKES. SOUTHERLY WINDS WILL BEGIN TO PICK UP THIS AFTERNOON AS A DEEPENING AREA OF LOW PRESSURE LIFTS NORTH ACROSS THE UPPER MIDWEST. WINDS WILL STRENGTHEN MORE TONIGHT AND WEDNESDAY AS THE PRESSURE GRADIENT INCREASES AHEAD OF THE ADVANCING LOW AND ITS ASSOCIATED COLD FRONT. SMALL CRAFT ADVISORIES HAVE BEEN ISSUES BEGINNING TONIGHT INTO WEDNESDAY THEN GALE WATCHES TAKE OVER WITH GALE FORCE WINDS POSSIBLE WEDNESDAY NIGHT AHEAD AND ALONG THE COLD FRONTAL PASSAGE. && .HYDROLOGY... THERE APPEARS TO BE SOME MINOR ICE JAMMING ON SOME OF THE CREEKS...WITH HYDROGRAPHS SUGGESTING THERE IS OR HAS BEEN SOME ICE FLOW ON THE CAYUGA CREEK...CAZENOVIA CREEK...BUFFALO CREEK...AND CATTARAUGUS CREEK...AS WELL AS A SPOTTER REPORT OF ICE FLOWS ON THE CONEWANGO. IN ALL OF THESE CASES...EXPECT THE ICE IS RATHER THIN...WITH ANY JAMS LIKELY TO BE RELATIVELY SHORT LIVED. THIS SAID...WILL CONTINUE TO MONITOR THESE CREEKS...AS IT IS POSSIBLE THERE WILL BE TEMPORARY AND MINOR ICE JAM FLOODING IN A FEW SPOTS OVERNIGHT. THIS SHOULD REMOVE AND MELT MUCH OF THE ICE WHICH HAS FORMED OVER THE PAST PERIOD OF COLD WEATHER. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...LAKE EFFECT SNOW WATCH FROM THURSDAY AFTERNOON THROUGH LATE FRIDAY NIGHT FOR NYZ006>008-012-019-020-085. WIND ADVISORY FROM 1 AM WEDNESDAY TO 1 PM EST THURSDAY FOR NYZ012-019-020-085. WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR NYZ007-008. WIND ADVISORY FROM 6 PM WEDNESDAY TO 1 PM EST THURSDAY FOR NYZ001>008-010-011-013-014-021. MARINE...GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY MORNING FOR LEZ020-040-041. SMALL CRAFT ADVISORY UNTIL 7 PM EST WEDNESDAY FOR LEZ020- 040-041. GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY AFTERNOON FOR LOZ030-042>045-062>065. SMALL CRAFT ADVISORY FROM 1 AM TO 9 PM EST WEDNESDAY FOR LOZ030. SMALL CRAFT ADVISORY FROM 4 AM TO 9 PM EST WEDNESDAY FOR LOZ042>045. && $$ SYNOPSIS...THOMAS NEAR TERM...THOMAS SHORT TERM...TMA LONG TERM...TMA AVIATION...APFFEL/TJP MARINE...THOMAS HYDROLOGY...APFFEL
AREA FORECAST DISCUSSION
NWS BUFFALO NY
747 AM EST MON JAN 28 2013 .SYNOPSIS... WARMER TEMPERATURES WILL ARRIVE TODAY AS A WARM FRONT PUSHES NORTH ACROSS THE REGION. THIS WARM UP WILL BRING THE THREAT FOR A PERIOD OF MIXED SNOW, SLEET AND FREEZING RAIN AT THE ONSET BEFORE CHANGING TO ALL RAIN FROM SOUTHWEST TO NORTHEAST. WARM AND RAINY WEATHER WILL CONTINUE TUESDAY AND WEDNESDAY. MUCH COLDER WEATHER WILL RETURN WEDNESDAY NIGHT AS A COLD FRONT CROSSES THE LOWER GREAT LAKES SETTING THE STAGE FOR ACCUMULATING LAKE EFFECT SNOWS THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... THE MAIN FORECAST CONCERN FOR THIS MORNING WILL CONTINUE TO BE FOR MIXED PRECIPITATION ADVANCING NORTH AND EAST ACROSS WESTERN NEW YORK. AT 7 AM THE 11Z RAP 925MB 0C ISOTHERM HAS LIFTED NORTH ACROSS CHAUTAUQUA AND WESTERN CATTARAUGUS COUNTIES THROUGH THE NIAGARA FRONTIER AND INTO THE GENESEE RIVER VALLEY. THE 3C ISOTHERM IS LOCATED FROM BUFFALO SOUTHWARD WITH SURFACE TEMPS 30 AND BELOW IN THESE AREAS. THIS INDICATES THAT WARM AIR IS OVERSPREADING THE COLD DENSE AIR AT THE SURFACE WITH PRECIPITATION PHASE CHANGE OCCURRING AS IT FALLS FROM COLD TO WARM TO COLD AGAIN. BUFFALO RADAR REFLECTIVITY SHOWING PRECIPITATION HAS SPREAD NORTH AND EAST ACROSS MUCH OF THE FORECAST AREA. FREEZING RAIN IS BEING REPORTED AT BUFFALO AND NIAGARA FALLS DOWN TO WELLSVILLE WHERE THE WARM NOSE ALOFT HAS RISEN GREATER THAN 3C. SOME DOWNSLOPING OFF THE CHAUTAUQUA RIDGE HAS ALLOWS TEMPS TO WARM TO 36 FOR DUNKIRK SO RAIN IS BEING REPORTED THERE. SNOW AND SLEET IS FALLING EAST OF I-390 WHERE THE WARM NOSE ALOFT HAS NOT WARMED ENOUGH FOR FREEZING RAIN. A PEEK AT THE CORRELATION COEFFICIENT PRODUCT ON THE DUAL-POL INDICATES A LARGE AREA OF SLEET MIXING IN OVER ALLEGANY COUNTY NORTH TO JUST WEST OF ROCHESTER AS CC VALUES WERE RUNNING BETWEEN 0.85 AND 0.95 INDICATING HYDROMETEORS BECOMING MIS-SHAPED...ICING/SLEET OCCURRING. THE PRECIPITATION IS BEING FORCED BY A WARM FRONT LIFTING NORTH ACROSS THE OHIO VALLEY AND ALONG A 60 KT LOW LEVEL JET OVER INDIANA AMD WESTERN OHIO. THROUGH TODAY THE WARM FRONT WILL LIFT NORTH ACROSS NEW YORK WITH BOUNDARY LAYER TEMPS CONTINUING TO WARM ABOVE FREEZING. IT STILL APPEARS THAT MOST LOCATIONS WILL RECEIVE ABOUT A 3 TO 5 HOUR PERIOD OF MIXED PRECIPITATION BEFORE CHANGING OVER TO RAIN. THE BEST CHANCE FOR THE LONGEST DURATION OF PROFILES SUPPORTIVE OF FREEZING PRECIPITATION WILL BE ACROSS EASTERN PORTIONS OF THE SOUTHERN TIER...FINGER LAKES AND EVENTUALLY NORTH COUNTRY. IT PROBABLY SHOULD BE NOTED THAT EVEN AFTER TEMPERATURES RISE ABOVE FREEZING...THE RECENT VERY COLD TEMPERATURES AND COLD GROUND MAY STILL SUPPORT AN INCREASED DURATION OF PRECIPITATION FREEZING ON SURFACES. MODEL QPF NOT OVERLY IMPRESSIVE WITH THIS EVENT WITH NEARLY ALL AVAILABLE GUIDANCE SUGGESTING AMOUNTS GENERALLY A HALF INCH OR LESS. SNOWFALL AMOUNTS GENERALLY IN THE 1-3 INCH RANGE FOR WESTERN NEW YORK WITH LONGER DURATION OF SNOW FOR THE NORTH COUNTRY LIKELY PRODUCING AS MUCH AS 3-5 INCHES THROUGH TODAY AND TONIGHT. ICE ACCUMULATIONS WILL HOLD TO A TENTH OF AN INCH OR LESS FOR THE MAJORITY OF LOCATIONS BUT SECTIONS OF THE SOUTHERN FINGER LAKES AND UPPER GENESEE VALLEY COULD SEE UPWARDS OF A QUARTER INCH ESPECIALLY IN COLDER VALLEYS. DUE TO THE ANTICIPATED FREEZING PRECIPITATION ON TOP OF THE INITIAL MINOR SNOWFALL AMOUNTS...A WINTER WEATHER ADVISORY REMAINS IN EFFECT TODAY FOR THE ENTIRE AREA. GOING INTO THE AFTERNOON EVENTUALLY THE WARMER AIR BUILDS DOWN TO THE SURFACE AND PROFILES WILL SUPPORT JUST PLAIN RAIN. THE ENDING TIMES OF THESE ADVISORIES CORRELATE WITH WHEN WE EXPECT PRECIPITATION TO BE ALL RAIN. HIGHS TODAY WILL REACH TO AROUND 40 FOR MUCH OF WNY WITH 30S AND EVEN UPPER 20S IN THE VALLEYS OF THE NORTH COUNTY WHERE LONGER DURATION OF SNOW AND MIXED PRECIP IS EXPECTED. THE LOW LEVEL JET HELPING TO DRIVE THE WEATHER TODAY WILL ALSO CREATE SOME GUSTY WINDS ACROSS THE SOUTHERN TIER DURING THE LATE MORNING AND AFTERNOON BUT WILL STAY BELOW WIND ADVISORY CRITERIA. FOR TONIGHT THE CENTER OF THE STORM SYSTEM WILL LIFT FROM NEAR MICHIGAN EASTWARD AND ACROSS OUR FORECAST AREA WITH THE WARM FRONT ALSO LIFTING NORTH AND EAST. EXPECT PRECIPITATION TYPE FOR ALL OF WESTERN AND LOWER CENTRAL NY TO BE RAIN WITH SNOW CONTINUING ACROSS THE NORTH COUNTRY. EVENTUALLY THE WARM NOSE WILL SPREAD OVER EASTERN LAKE ONTARIO COUNTIES AS WELL WITH SLEET AND FREEZING RAIN MIXED PRECIP. SURFACE TEMPS WILL REMAIN NEARLY STEADY OVERNIGHT IN THE UPPER 30S TO LOWER 40S ACROSS WESTERN NY AND EVENTUALLY INCHING ABOVE FREEZING ACROSS THE NORTH COUNTY. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... WET AND VERY MILD WEATHER WILL CHARACTERIZE THE INITIAL PORTION OF THIS PERIOD AS WARM AIR SURGES NORTHWARDS ACROSS THE REGION AHEAD OF AN APPROACHING COLD FRONT THAT WILL MARCH EASTWARDS ACROSS THE GREAT LAKES WEDNESDAY NIGHT...CROSSING WESTERN AND CENTRAL NEW YORK WHILE USHERING IN THE RETURN OF WINTER ALONG WITH THE LIKELIHOOD OF SIGNIFICANT LAKE EFFECT SNOWS FOR THE LATTER HALF OF THE WEEK. THE BULK OF THE INITIAL WAVE OF PRECIPITATION ASSOCIATED WITH THE WARM FRONT CURRENTLY MOVING INTO WESTERN NEW YORK WILL HAVE PUSH EAST ACROSS NEW ENGLAND BY TUESDAY MORNING...HOWEVER A LINGERING SURFACE TROUGH ALONG WITH PLENTY OF MOISTURE REMAINING IN PLACE SHOULD ALLOW FOR AT LEAST A CHANCE OF SHOWERS TO START OUT THE DAY WITH POPS RAMPING UP ONCE AGAIN BY THE AFTERNOON AS ANOTHER WARM FRONT LIFTS NORTH ACROSS THE REGION WITH DEEPER MOISTURE RIDING OVER THE TOP OF AN UPPER LEVEL RIDGE CROSSING THE OHIO VALLEY AND LOWER GREAT LAKES. THIS WARM FRONTAL BOUNDARY MARKS THE LEADING EDGE OF AN EXCEPTIONALLY WARM AIRMASS WITH 850MB TEMPERATURES AS HIGH AS +10C ADVECTING NORTH INTO WESTERN AND CENTRAL NEW YORK. THIS AIRMASS WILL MAKE IT FEEL MORE LIKE LATE MARCH/EARLY APRIL AS TEMPERATURES RISE INTO THE LOWER 50S FROM THE GENESEE VALLEY WEST WHILE AREAS EAST WILL STAY IN THE 40S. THE WARMUP WILL CONTINUE UNABATED TUESDAY NIGHT WITH ANY DIURNAL COOLING BEING OFFSET BY THE CONTINUED WARM ADVECTION ALONG WITH CLOUD COVER/ONGOING PRECIP AS THE WARM FRONTAL BAND LIFTS NORTH AND EAST ACROSS THE AREA. EXTENSIVE ISENTROPIC LIFTING ALONG THIS FRONTAL BAND WILL RESULT IN QPF APPROACHING HALF AN INCH OVERNIGHT...HOWEVER THERE ARE DISRCREPANCIES AMONG THE MODELS ON THE EXACT PLACEMENT OF THE FRONT AND ASSOCIATED AXIS OF HEAVIEST RAIN. HOWEVER AT THIS POINT IT APPEARS THAT GREATEST POPS WILL BE NORTH OF THE THRUWAY WHILE AREAS SOUTH MAY STAY IN THE DRIER WARM SECTOR. TEMPERATURES ACROSS THE NORTH COUNTRY WILL GRADUALLY WARM THROUGH THE NIGHT INTO THE LOWER 50S WHILE THE REST OF THE FORECAST AREA WILL SLOWLY CLIMB INTO THE LOW TO MID 50S BY DAYBREAK WEDNESDAY. ANOTHER ISSUE ASSOCIATED WITH THE ADVECTION OF WARM MOIST AIR NORTHWARDS ACROSS THE COLD LAKES WILL BE FOG AND HAVE UPDATED GRIDS TO INCLUDE THIS. AS THE WINDS WILL BE RELATIVELY BREEZY OUT OF THE SOUTH...WILL ASSUME THAT MOST OF THE LAND AREAS OF THE FORECAST AREA SHOULD STAY FOG FREE...HOWEVER THE NIAGARA FRONTIER FROM DOWNTOWN BUFFALO NORTH ACROSS NIAGARA COUNTY MAY BE THE RECIPIENTS OF ADVCETION FOG OFF LAKE ERIE IF THERE IS ANY SOUTHWESTERLY COMPONENT TO THE WINDS. WE WILL SEE A VERY BALMY TO WEDNESDAY AS THE AREA WILL BE FIRMLY IN THE WARM SECTOR OF A BROAD AREA OF LOW PRESSURE EXTENDING ACROSS THE MIDWEST AND CENTRAL GREAT LAKES. THERE ARE SIGNIFICANT DIFFERENCES BETWEEN THE GFS/NAM WHICH RAPIDLY DEVELOP A VERY DEEP LOW OVER THE CENTRAL GREAT LAKES FROM A WAVE MOVING UP THE FRONT MARKING THE BOUDNARY BETWEEN THE WARM AIR OVER THE EASTERN U.S. AND A SUB-ARCTIC BLAST OF COLD AIR DROPPING ACROSS THE NORTHERN PLAINS OUT OF CANADA. ON THE OTHER HAND THE ECMWF FEATURES A WEAKER SERIES OF WAVES THAT WORK THEIR WAY ALONG THE SLOWER MOVING FRONTAL BOUDNARY...WITH NO SINGLE LOW BECOMING DOMINANT. THIS HAS A SIGNIFICANT IMPACT ON THE WIND FORECAST FOR OUR AREA AS A NAM/GFS SOLUTION WITH THE DEEP LOW TRACKING OUT THE CENTRAL LAKES COULD MEAN A SIGIFICANT WIND EVENT ACROSS THE AREA...WHILST THE ECMWF SOLUTION WOULD BE MUCH MORE BENIGN. GIVEN THE UNCERTAINTY...THE CURRENT FORECAST WILL LEAN MORE TOWARDS THE ECMWF SOLUTION...WHICH ALSO PRESERVES CONTINUITY WITH THE PREVIOUS FORECAST. THUS...STILL EXPECT A FRONTAL PASSAGE LATE WEDENSDAY AFTERNOON/WEDNESDAY EVENING WITH BREEZY...BUT NOT DAMAGING...SOUTH WINDS VEERING TO THE SOUTHWEST AND EVENTUALLY TO THE WEST AS TEMPERATURES FALL FROM THE MID 50S EARLY WEDNESDAY TO THE UPPER 20S/LOWER 30S WEDNESDAY NIGHT. ACCOMPANYING THIS FRONTAL PASSAGE WILL BE ANOTHER DECENT SOAKING RAIN WITH A QUARTER TO A HALF INCH OF QPF POSSIBLE...DEPENDING ON HOW FAST THE FRONT MOVES THROUGH. BY EARLY THURSDAY MORNING...WE SHOULD SEE TEMPERATURES COOL TO THE POINT THAT LAKE EFFECT SHOWERS SHOULD BEGIN TO DEVELOP... && .LONG TERM /THURSDAY THROUGH SUNDAY/... FOLLOWING THE PASSAGE OF THE MIDWEEK COLD FRONT...THE MEDIUM RANGE GUIDANCE REMAINS IN EXCELLENT AGREEMENT THAT BROAD UPPER TROUGHING WILL BECOME RE-ESTABLISHED ACROSS THE GREAT LAKES AND NORTHEAST THURSDAY AND FRIDAY...WITH TEMPERATURES TUMBLING BACK TO WELL BELOW AVERAGE AS PROGRESSIVELY COLDER AIR FLOODS EAST ACROSS THE GREAT LAKES. WHILE THE INCOMING COLDER AIRMASS DOES NOT LOOK TO BE NEARLY QUITE AS COLD AS THE ONE THAT AFFECTED OUR REGION FOR MUCH OF LAST WEEK...850 MB TEMPS STILL LOOK TO DROP TO THE VICINITY OF -18C TO -20C...WHICH WILL BE PLENTY COLD ENOUGH TO RESULT IN DAYTIME HIGHS FALLING BACK TO AROUND 20 BY FRIDAY...AND THE DEVELOPMENT OF ANOTHER ROUND OF POTENTIALLY SIGNIFICANT LAKE EFFECT SNOWS DOWNWIND OF THE LAKES. WHILE IT IS STILL TOO EARLY TO DEFINITIVELY PIN DOWN EXACTLY WHICH AREAS THE LAKE SNOWS MIGHT FOCUS ON...BOTH THE GFS/ECMWF CONTINUE TO SUGGEST THAT THE LAKE EFFECT ACTIVITY WILL DEVELOP IN A WESTERLY FLOW REGIME LATER WEDNESDAY NIGHT/EARLY THURSDAY...BEFORE INTENSIFYING OVER TIME THURSDAY AS AN INITIALLY DRY AIRMASS MOISTENS IN ADVANCE OF AN APPROACHING SECONDARY SURFACE TROUGH. AFTER THAT TIME...SOME DISAGREEMENT EMERGES WITH THE ECMWF PUSHING THE SURFACE TROUGH THROUGH LATER THURSDAY NIGHT/EARLY FRIDAY WITH THE LOW LEVEL FLOW GOING MORE NORTHWESTERLY ON FRIDAY FOLLOWING ITS PASSAGE... WHILE THE GFS ESSENTIALLY WASHES OUT THE TROUGH AND KEEPS MORE OF A WESTERLY FLOW IN PLACE THROUGH FRIDAY. DOWNWIND OF LAKE ERIE...ALL OF THIS WOULD SUGGEST THE STRONGEST AND MOST ORGANIZED LAKE SNOWS INITIALLY DEVELOPING ACROSS THE WESTERN SOUTHERN TIER AND SOUTHERN ERIE AND WYOMING COUNTIES LATER WEDNESDAY NIGHT INTO THURSDAY...THEN EITHER LINGERING PRETTY MUCH IN PLACE THROUGH FRIDAY...OR SHIFTING A BIT FURTHER SOUTH TO AREAS SOUTHEAST OF THE LAKE DEPENDING UPON WHETHER THERE ACTUALLY IS A SECONDARY TROUGH PASSAGE AND ASSOCIATED WIND SHIFT. SIMILARLY...THE LAKE ONTARIO LAKE SNOWS WOULD LIKELY DEVELOP ACROSS THE TUG HILL REGION WEDNESDAY NIGHT INTO THURSDAY...THEN EITHER REMAIN IN PLACE THROUGH FRIDAY OR MIGRATE SOUTHWARD TO AREAS SOUTHEAST OF THE LAKE. CONSIDERING THE ABOVE...WILL INDICATE SOME BROAD AREAS OF HIGHER PRECIPITATION CHANCES EAST OF THE LAKES ON THURSDAY...THEN EXPAND THESE TO COVER AREAS BOTH EAST AND SOUTHEAST OF THE LAKES THURSDAY NIGHT AND FRIDAY GIVEN THE INCREASING UNCERTAINTY IN WIND DIRECTION AND RESULTANT BAND PLACEMENT DURING THESE TWO PERIODS. IN TERMS OF ACTUAL POP VALUES...WILL INCREASE POPS TO LOW LIKELY WITHIN THE MORE FAVORED LAKE EFFECT REGIONS ON THURSDAY GIVEN CONTINUED GOOD AGREEMENT DURING THIS TIME FRAME...BEFORE DROPPING THESE BACK TO HIGH CHANCE FOR THURSDAY NIGHT AND FRIDAY GIVEN THE INCREASING FORECAST UNCERTAINTY. OUTSIDE OF THE MORE FAVORED LAKE EFFECT AREAS...WILL KEEP SOMEWHAT LOWER CHANCE POPS IN PLAY BOTH TO COVER THE APPROACH AND POSSIBLE PASSAGE OF THE SECONDARY SURFACE TROUGH... AND TO ALSO REFLECT THE INHERENT UNCERTAINTY IN DELINEATING SPECIFIC AREAS OF LAKE EFFECT THIS FAR OUT. NEEDLESS TO SAY...IT IS STILL WAY TOO EARLY TO EVEN CONSIDER ANY FLAGS FOR THIS PERIOD JUST YET...THOUGH GIVEN THE CONSISTENTLY FAVORABLE SYNOPTIC PATTERN AND THERMODYNAMIC ENVIRONMENT SEEN IN THE GUIDANCE IN THE THURSDAY-FRIDAY PERIOD...WILL ELECT TO ADD AN INITIAL MENTION OF THE LAKE EFFECT POTENTIAL TO THE HWO. LATER ON IN THE PERIOD...BOTH THE GFS AND ECMWF INDICATE THAT A DECENT CLIPPER-TYPE SYSTEM WILL ROUND THE BASE OF THE MEAN TROUGH AND WORK INTO OUR REGION SOMETIME BETWEEN FRIDAY NIGHT AND SATURDAY...THEN EXIT TO OUR EAST ON SUNDAY WITH A REINFORCING SHOT OF COLDER AND DRIER AIR FOLLOWING ITS PASSAGE. IN TERMS OF PRECIPITATION CHANCES...THIS FEATURE WILL BRING A MORE GENERAL CHANCE OF SNOW SHOWERS BACK INTO THE AREA FOR THE WEEKEND...WHILE ALSO INFLUENCING THE EVOLUTION OF THE LOW-LEVEL WIND FIELD...WHICH IN TURN WILL IMPACT THE ULTIMATE POSITION AND STRENGTH OF ANY LAKE SNOWS. GIVEN THE DISTANT DAY 6-7 TIME FRAME AND THE TYPICAL FORECAST UNCERTAINTY IN BOTH THE TIMING/TRACK/STRENGTH OF THIS FEATURE AND ITS EXACT INFLUENCE ON THE LOW LEVEL WIND FIELDS...FOR NOW HAVE JUST TRENDED POPS BACK TO THE BROADBRUSH LOW-MID CHANCE RANGE FOR NEXT WEEKEND. && .AVIATION /13Z MONDAY THROUGH FRIDAY/... FREEZING RAIN HAS WORKED NORTH ACROSS FAR WESTERN NY WITH A MIX OF SNOW AND SLEET FOR KROC AND ALL SNOW NOW ARRIVING AT KART. CIGS AND VIS ARE RUNNING MVFR/IFR IN ALL AREAS. A 50 TO 60 KNOT LOW LEVEL JET WHICH IS FORCING THIS PRECIPITATION WILL SHIFT OVER THE REGION BRINGING THE POSSIBILITY OF SOME LOW LEVEL WIND SHEAR TODAY AS AN INVERSION ALOFT SEALS OFF THESE HIGH WINDS FROM THE SURFACE. GOING INTO THE AFTERNOON FOR WNY...THE AIR MASS WILL BECOME WARM ENOUGH DOWN TO THE SURFACE FOR A CHANGE OVER TO ALL RAIN. EXPECT THE LIQUID PRECIP TO TAPER OFF CLOSER TO THE EVENING AND TRANSITION TO DRIZZLE AND LIGHT FOG. PRECIPITATION WILL REMAIN IN A MIXED PHASE WELL INTO THE EVENING AND OVERNIGHT FOR KART. OUTLOOK... TUESDAY...MVFR WITH RAIN SHOWERS LIKELY. WEDNESDAY...MVFR/IFR WITH RAIN OR SNOW SHOWERS LIKELY. THURSDAY AND FRIDAY...MVFR/LOCALIZED IFR IN LAKE EFFECT SNOW SHOWERS. && .MARINE... A WARM FRONT IS LIFTING NORTH TOWARD THE LAKES EARLY THIS MORNING. AN ASSOCIATED LOW LEVEL JET WILL ALSO BRING SOME HIGHER WINDS TO LAKE ERIE WHERE A SMALL CRAFT ADVISORY HAS BEEN ISSUED. A WINTRY MIX OF PRECIPITATION WILL OCCUR OVER THE LAKES THROUGH TODAY AS THE WARMER AIR SLOWLY WORKS NORTHWARD. SOUTHERLY WINDS WILL BUILD WAVES ALONG THE NORTHERN LAKE SHORES TODAY THROUGH WEDNESDAY BUT EXPECT THESE TO GENERALLY REMAIN BELOW SMALL CRAFT CRITERIA. && .HYDROLOGY... WITH THE UPCOMING STRONG WARMUP...NORMALLY ONE WOULD EXPECT THE POTENTIAL FOR SOME ICE JAMS ON AREA CREEKS GIVEN THE TIME OF YEAR. THIS SAID...THIS WINTER HAS BEEN RELATIVELY MILD MUCH OF THE TIME... WITH THE BULK OF ANY ICE FORMATION ON CREEKS LIKELY COMING DURING OUR STRONG COLD SPELL OF THE PAST WEEK...WITH ANY ICE PROBABLY NOT YET REACHING THICKNESSES THAT WOULD POSE A SIGNIFICANT ICE JAM THREAT. THUS...WHILE THESE CANNOT BE AT ALL RULED OUT...AT THIS POINT WE DO NOT ANTICIPATE A STRONG THREAT OF ICE JAMS AND RESULTANT FLOODING ISSUES DURING THE UPCOMING WARMUP. WITH ICE JAMS LIKELY NOT A HUGE CONCERN...AT THIS POINT ANY HYDRO ISSUES THIS WEEK WILL PROBABLY HAVE TO INSTEAD BE DRIVEN BY A COMBINATION OF SNOWMELT AND RAINFALL. WITH OVERALL RAINFALL AMOUNTS LOOKING TO BE RELATIVELY LIGHT THROUGH TUESDAY... /GENERALLY ON THE ORDER OF A TENTH OR TWO TENTHS OF AN INCH PER EVERY 12 HOURS/...FEEL THAT ANY HYDRO CONCERNS SHOULD BE RELATIVELY MINIMAL THROUGH THAT TIME. AFTER THAT...THERE WILL BE THE POTENTIAL FOR SOMEWHAT HEAVIER SHOWERS ALONG AND IN ADVANCE OF A COLD FRONT TUESDAY AND WEDNESDAY...WHICH COULD LEAD TO A SOMEWHAT HIGHER POTENTIAL FOR LOCALIZED HYDRO ISSUES DURING THAT TIME FRAME. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ005>008. WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR NYZ003-004-013-014. WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NYZ001-002-010>012-019>021-085. MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LEZ040- 041. && $$ SYNOPSIS...SMITH NEAR TERM...SMITH SHORT TERM...WOOD LONG TERM...JJR AVIATION...SMITH MARINE...SMITH HYDROLOGY...JJR
AREA FORECAST DISCUSSION
NWS BUFFALO NY
530 AM EST MON JAN 28 2013 .SYNOPSIS... WARMER TEMPERATURES WILL ARRIVE TODAY AS A WARM FRONT PUSHES NORTH ACROSS THE REGION. THIS WARM UP WILL BRING THE THREAT FOR A PERIOD OF MIXED SNOW, SLEET AND FREEZING RAIN AT THE ONSET BEFORE CHANGING TO ALL RAIN FROM SOUTHWEST TO NORTHEAST. WARM AND RAINY WEATHER WILL CONTINUE TUESDAY AND WEDNESDAY. MUCH COLDER WEATHER WILL RETURN WEDNESDAY NIGHT AS A COLD FRONT CROSSES THE LOWER GREAT LAKES SETTING THE STAGE FOR ACCUMULATING LAKE EFFECT SNOWS THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... THE MAIN FORECAST CONCERN FOR THIS MORNING WILL CONTINUE TO BE FOR MIXED PRECIPITATION ADVANCING NORTH AND EAST ACROSS WESTERN NEW YORK. AT 5 AM THE 09Z RAP 925MB 0C ISOTHERM HAS WORKED NORTH ACROSS FAR WESTERN NEW YORK AND IS SPREADING EAST INTO THE GENESEE RIVER VALLEY AND SOUTHERN FINGER LAKES WITH SURFACE TEMPS STILL IN THE 20S. THIS INDICATES THAT WARM AIR IS OVERSPREADING THE COLD DENSE AIR AT THE SURFACE WITH PRECIPITATION PHASE CHANGE OCCURRING AS IT FALLS FROM COLD TO WARM TO COLD AGAIN. BUFFALO RADAR REFLECTIVITY SHOWING SNOW HAS SPREAD NORTH AND EAST ACROSS THE SOUTHERN TIER...NIAGARA FRONTIER AND INTO THE GENESEE VALLEY. SNOW IS BEING REPORTED AT OLEAN NORTH TO BUFFALO...NIAGARA FALLS AND ROCHESTER WITH FREEZING RAIN AT DUNKIRK ON SURFACE OBSERVATIONS. AS WARM AIR INCREASES ALOFT...SLEET THEN FREEZING RAIN WILL MIX IN AND CHANGE OVER. A PEEK AT THE CORRELATION COEFFICIENT PRODUCT ON THE DUAL-POL INDICATED SLEET ALREADY MIXING IN EARLIER NEAR SALAMANCA AND OLEAN AND MOST RECENTLY IS MIXING IN OVER MUCH OF CHAUTAUQUA...CATTARAUGUS AND INTO ERIE COUNTY AS CC VALUES WERE RUNNING BETWEEN 0.85 AND 0.95 INDICATING HYDROMETEORS BECOMING MIS-SHAPED...ICING/SLEET OCCURRING. THE PRECIPITATION IS BEING FORCED BY A WARM FRONT LIFTING NORTH ACROSS THE OHIO VALLEY AND ALONG A 60 KT LOW LEVEL JET OVER INDIANA. THROUGH TODAY THE WARM FRONT WILL LIFT NORTH ACROSS NEW YORK WITH BOUNDARY LAYER TEMPS SLOWLY WARMING ABOVE FREEZING. IT STILL APPEARS THAT MOST LOCATIONS WILL RECEIVE ABOUT A 3 TO 5 HOUR PERIOD OF MIXED PRECIPITATION BEFORE CHANGING OVER TO RAIN. THE BEST CHANCE FOR THE LONGEST DURATION OF PROFILES SUPPORTIVE OF FREEZING PRECIPITATION WILL BE ACROSS EASTERN PORTIONS OF THE SOUTHERN TIER...FINGER LAKES AND EVENTUALLY NORTH COUNTRY. IT PROBABLY SHOULD BE NOTED THAT EVEN AFTER TEMPERATURES RISE ABOVE FREEZING...THE RECENT VERY COLD TEMPERATURES AND COLD GROUND MAY STILL SUPPORT AN INCREASED DURATION OF PRECIPITATION FREEZING ON SURFACES. MODEL QPF NOT OVERLY IMPRESSIVE WITH THIS EVENT WITH NEARLY ALL AVAILABLE GUIDANCE SUGGESTING AMOUNTS GENERALLY A HALF INCH OR LESS. SNOWFALL AMOUNTS GENERALLY IN THE 1-3 INCH RANGE FOR WESTERN NEW YORK WITH LONGER DURATION OF SNOW FOR THE NORTH COUNTRY LIKELY PRODUCING AS MUCH AS 3-5 INCHES THROUGH TODAY AND TONIGHT. ICE ACCUMULATIONS WILL HOLD TO A TENTH OF AN INCH OR LESS FOR THE MAJORITY OF LOCATIONS BUT SECTIONS OF THE SOUTHERN FINGER LAKES AND UPPER GENESEE VALLEY COULD SEE UPWARDS OF A QUARTER INCH ESPECIALLY IN COLDER VALLEYS. DUE TO THE ANTICIPATED FREEZING PRECIPITATION ON TOP OF THE INITIAL MINOR SNOWFALL AMOUNTS...A WINTER WEATHER ADVISORY REMAINS IN EFFECT TODAY FOR THE ENTIRE AREA. GOING INTO THE AFTERNOON EVENTUALLY THE WARMER AIR BUILDS DOWN TO THE SURFACE AND PROFILES WILL SUPPORT JUST PLAIN RAIN. THE ENDING TIMES OF THESE ADVISORIES CORRELATE WITH WHEN WE EXPECT PRECIPITATION TO BE ALL RAIN. HIGHS TODAY WILL REACH TO AROUND 40 FOR MUCH OF WNY WITH 30S AND EVEN UPPER 20S IN THE VALLEYS OF THE NORTH COUNTY WHERE LONGER DURATION OF SNOW AND MIXED PRECIP IS EXPECTED. THE LOW LEVEL JET HELPING TO DRIVE THE WEATHER TODAY WILL ALSO CREATE SOME GUSTY WINDS ACROSS THE SOUTHERN TIER DURING THE LATE MORNING AND AFTERNOON BUT WILL STAY BELOW WIND ADVISORY CRITERIA. FOR TONIGHT THE CENTER OF THE STORM SYSTEM WILL LIFT FROM NEAR MICHIGAN EASTWARD AND ACROSS OUR FORECAST AREA WITH THE WARM FRONT ALSO LIFTING NORTH AND EAST. EXPECT PRECIPITATION TYPE FOR ALL OF WESTERN AND LOWER CENTRAL NY TO BE RAIN WITH SNOW CONTINUING ACROSS THE NORTH COUNTRY. EVENTUALLY THE WARM NOSE WILL SPREAD OVER EASTERN LAKE ONTARIO COUNTIES AS WELL WITH SLEET AND FREEZING RAIN MIXED PRECIP. SURFACE TEMPS WILL REMAIN NEARLY STEADY OVERNIGHT IN THE UPPER 30S TO LOWER 40S ACROSS WESTERN NY AND EVENTUALLY INCHING ABOVE FREEZING ACROSS THE NORTH COUNTY. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... WET AND VERY MILD WEATHER WILL CHARACTERIZE THE INITIAL PORTION OF THIS PERIOD AS WARM AIR SURGES NORTHWARDS ACROSS THE REGION AHEAD OF AN APPROACHING COLD FRONT THAT WILL MARCH EASTWARDS ACROSS THE GREAT LAKES WEDNESDAY NIGHT...CROSSING WESTERN AND CENTRAL NEW YORK WHILE USHERING IN THE RETURN OF WINTER ALONG WITH THE LIKELIHOOD OF SIGNIFICANT LAKE EFFECT SNOWS FOR THE LATTER HALF OF THE WEEK. THE BULK OF THE INITIAL WAVE OF PRECIPITATION ASSOCIATED WITH THE WARM FRONT CURRENTLY MOVING INTO WESTERN NEW YORK WILL HAVE PUSH EAST ACROSS NEW ENGLAND BY TUESDAY MORNING...HOWEVER A LINGERING SURFACE TROUGH ALONG WITH PLENTY OF MOISTURE REMAINING IN PLACE SHOULD ALLOW FOR AT LEAST A CHANCE OF SHOWERS TO START OUT THE DAY WITH POPS RAMPING UP ONCE AGAIN BY THE AFTERNOON AS ANOTHER WARM FRONT LIFTS NORTH ACROSS THE REGION WITH DEEPER MOISTURE RIDING OVER THE TOP OF AN UPPER LEVEL RIDGE CROSSING THE OHIO VALLEY AND LOWER GREAT LAKES. THIS WARM FRONTAL BOUNDARY MARKS THE LEADING EDGE OF AN EXCEPTIONALLY WARM AIRMASS WITH 850MB TEMPERATURES AS HIGH AS +10C ADVECTING NORTH INTO WESTERN AND CENTRAL NEW YORK. THIS AIRMASS WILL MAKE IT FEEL MORE LIKE LATE MARCH/EARLY APRIL AS TEMPERATURES RISE INTO THE LOWER 50S FROM THE GENESEE VALLEY WEST WHILE AREAS EAST WILL STAY IN THE 40S. THE WARMUP WILL CONTINUE UNABATED TUESDAY NIGHT WITH ANY DIURNAL COOLING BEING OFFSET BY THE CONTINUED WARM ADVECTION ALONG WITH CLOUD COVER/ONGOING PRECIP AS THE WARM FRONTAL BAND LIFTS NORTH AND EAST ACROSS THE AREA. EXTENSIVE ISENTROPIC LIFTING ALONG THIS FRONTAL BAND WILL RESULT IN QPF APPROACHING HALF AN INCH OVERNIGHT...HOWEVER THERE ARE DISRCREPANCIES AMONG THE MODELS ON THE EXACT PLACEMENT OF THE FRONT AND ASSOCIATED AXIS OF HEAVIEST RAIN. HOWEVER AT THIS POINT IT APPEARS THAT GREATEST POPS WILL BE NORTH OF THE THRUWAY WHILE AREAS SOUTH MAY STAY IN THE DRIER WARM SECTOR. TEMPERATURES ACROSS THE NORTH COUNTRY WILL GRADUALLY WARM THROUGH THE NIGHT INTO THE LOWER 50S WHILE THE REST OF THE FORECAST AREA WILL SLOWLY CLIMB INTO THE LOW TO MID 50S BY DAYBREAK WEDNESDAY. ANOTHER ISSUE ASSOCIATED WITH THE ADVECTION OF WARM MOIST AIR NORTHWARDS ACROSS THE COLD LAKES WILL BE FOG AND HAVE UPDATED GRIDS TO INCLUDE THIS. AS THE WINDS WILL BE RELATIVELY BREEZY OUT OF THE SOUTH...WILL ASSUME THAT MOST OF THE LAND AREAS OF THE FORECAST AREA SHOULD STAY FOG FREE...HOWEVER THE NIAGARA FRONTIER FROM DOWNTOWN BUFFALO NORTH ACROSS NIAGARA COUNTY MAY BE THE RECIPIENTS OF ADVCETION FOG OFF LAKE ERIE IF THERE IS ANY SOUTHWESTERLY COMPONENT TO THE WINDS. WE WILL SEE A VERY BALMY TO WEDNESDAY AS THE AREA WILL BE FIRMLY IN THE WARM SECTOR OF A BROAD AREA OF LOW PRESSURE EXTENDING ACROSS THE MIDWEST AND CENTRAL GREAT LAKES. THERE ARE SIGNIFICANT DIFFERENCES BETWEEN THE GFS/NAM WHICH RAPIDLY DEVELOP A VERY DEEP LOW OVER THE CENTRAL GREAT LAKES FROM A WAVE MOVING UP THE FRONT MARKING THE BOUDNARY BETWEEN THE WARM AIR OVER THE EASTERN U.S. AND A SUB-ARCTIC BLAST OF COLD AIR DROPPING ACROSS THE NORTHERN PLAINS OUT OF CANADA. ON THE OTHER HAND THE ECMWF FEATURES A WEAKER SERIES OF WAVES THAT WORK THEIR WAY ALONG THE SLOWER MOVING FRONTAL BOUDNARY...WITH NO SINGLE LOW BECOMING DOMINANT. THIS HAS A SIGNIFICANT IMPACT ON THE WIND FORECAST FOR OUR AREA AS A NAM/GFS SOLUTION WITH THE DEEP LOW TRACKING OUT THE CENTRAL LAKES COULD MEAN A SIGIFICANT WIND EVENT ACROSS THE AREA...WHILST THE ECMWF SOLUTION WOULD BE MUCH MORE BENIGN. GIVEN THE UNCERTAINTY...THE CURRENT FORECAST WILL LEAN MORE TOWARDS THE ECMWF SOLUTION...WHICH ALSO PRESERVES CONTINUITY WITH THE PREVIOUS FORECAST. THUS...STILL EXPECT A FRONTAL PASSAGE LATE WEDENSDAY AFTERNOON/WEDNESDAY EVENING WITH BREEZY...BUT NOT DAMAGING...SOUTH WINDS VEERING TO THE SOUTHWEST AND EVENTUALLY TO THE WEST AS TEMPERATURES FALL FROM THE MID 50S EARLY WEDNESDAY TO THE UPPER 20S/LOWER 30S WEDNESDAY NIGHT. ACCOMPANYING THIS FRONTAL PASSAGE WILL BE ANOTHER DECENT SOAKING RAIN WITH A QUARTER TO A HALF INCH OF QPF POSSIBLE...DEPENDING ON HOW FAST THE FRONT MOVES THROUGH. BY EARLY THURSDAY MORNING...WE SHOULD SEE TEMPERATURES COOL TO THE POINT THAT LAKE EFFECT SHOWERS SHOULD BEGIN TO DEVELOP... && .LONG TERM /THURSDAY THROUGH SUNDAY/... FOLLOWING THE PASSAGE OF THE MIDWEEK COLD FRONT...THE MEDIUM RANGE GUIDANCE REMAINS IN EXCELLENT AGREEMENT THAT BROAD UPPER TROUGHING WILL BECOME RE-ESTABLISHED ACROSS THE GREAT LAKES AND NORTHEAST THURSDAY AND FRIDAY...WITH TEMPERATURES TUMBLING BACK TO WELL BELOW AVERAGE AS PROGRESSIVELY COLDER AIR FLOODS EAST ACROSS THE GREAT LAKES. WHILE THE INCOMING COLDER AIRMASS DOES NOT LOOK TO BE NEARLY QUITE AS COLD AS THE ONE THAT AFFECTED OUR REGION FOR MUCH OF LAST WEEK...850 MB TEMPS STILL LOOK TO DROP TO THE VICINITY OF -18C TO -20C...WHICH WILL BE PLENTY COLD ENOUGH TO RESULT IN DAYTIME HIGHS FALLING BACK TO AROUND 20 BY FRIDAY...AND THE DEVELOPMENT OF ANOTHER ROUND OF POTENTIALLY SIGNIFICANT LAKE EFFECT SNOWS DOWNWIND OF THE LAKES. WHILE IT IS STILL TOO EARLY TO DEFINITIVELY PIN DOWN EXACTLY WHICH AREAS THE LAKE SNOWS MIGHT FOCUS ON...BOTH THE GFS/ECMWF CONTINUE TO SUGGEST THAT THE LAKE EFFECT ACTIVITY WILL DEVELOP IN A WESTERLY FLOW REGIME LATER WEDNESDAY NIGHT/EARLY THURSDAY...BEFORE INTENSIFYING OVER TIME THURSDAY AS AN INITIALLY DRY AIRMASS MOISTENS IN ADVANCE OF AN APPROACHING SECONDARY SURFACE TROUGH. AFTER THAT TIME...SOME DISAGREEMENT EMERGES WITH THE ECMWF PUSHING THE SURFACE TROUGH THROUGH LATER THURSDAY NIGHT/EARLY FRIDAY WITH THE LOW LEVEL FLOW GOING MORE NORTHWESTERLY ON FRIDAY FOLLOWING ITS PASSAGE... WHILE THE GFS ESSENTIALLY WASHES OUT THE TROUGH AND KEEPS MORE OF A WESTERLY FLOW IN PLACE THROUGH FRIDAY. DOWNWIND OF LAKE ERIE...ALL OF THIS WOULD SUGGEST THE STRONGEST AND MOST ORGANIZED LAKE SNOWS INITIALLY DEVELOPING ACROSS THE WESTERN SOUTHERN TIER AND SOUTHERN ERIE AND WYOMING COUNTIES LATER WEDNESDAY NIGHT INTO THURSDAY...THEN EITHER LINGERING PRETTY MUCH IN PLACE THROUGH FRIDAY...OR SHIFTING A BIT FURTHER SOUTH TO AREAS SOUTHEAST OF THE LAKE DEPENDING UPON WHETHER THERE ACTUALLY IS A SECONDARY TROUGH PASSAGE AND ASSOCIATED WIND SHIFT. SIMILARLY...THE LAKE ONTARIO LAKE SNOWS WOULD LIKELY DEVELOP ACROSS THE TUG HILL REGION WEDNESDAY NIGHT INTO THURSDAY...THEN EITHER REMAIN IN PLACE THROUGH FRIDAY OR MIGRATE SOUTHWARD TO AREAS SOUTHEAST OF THE LAKE. CONSIDERING THE ABOVE...WILL INDICATE SOME BROAD AREAS OF HIGHER PRECIPITATION CHANCES EAST OF THE LAKES ON THURSDAY...THEN EXPAND THESE TO COVER AREAS BOTH EAST AND SOUTHEAST OF THE LAKES THURSDAY NIGHT AND FRIDAY GIVEN THE INCREASING UNCERTAINTY IN WIND DIRECTION AND RESULTANT BAND PLACEMENT DURING THESE TWO PERIODS. IN TERMS OF ACTUAL POP VALUES...WILL INCREASE POPS TO LOW LIKELY WITHIN THE MORE FAVORED LAKE EFFECT REGIONS ON THURSDAY GIVEN CONTINUED GOOD AGREEMENT DURING THIS TIME FRAME...BEFORE DROPPING THESE BACK TO HIGH CHANCE FOR THURSDAY NIGHT AND FRIDAY GIVEN THE INCREASING FORECAST UNCERTAINTY. OUTSIDE OF THE MORE FAVORED LAKE EFFECT AREAS...WILL KEEP SOMEWHAT LOWER CHANCE POPS IN PLAY BOTH TO COVER THE APPROACH AND POSSIBLE PASSAGE OF THE SECONDARY SURFACE TROUGH... AND TO ALSO REFLECT THE INHERENT UNCERTAINTY IN DELINEATING SPECIFIC AREAS OF LAKE EFFECT THIS FAR OUT. NEEDLESS TO SAY...IT IS STILL WAY TOO EARLY TO EVEN CONSIDER ANY FLAGS FOR THIS PERIOD JUST YET...THOUGH GIVEN THE CONSISTENTLY FAVORABLE SYNOPTIC PATTERN AND THERMODYNAMIC ENVIRONMENT SEEN IN THE GUIDANCE IN THE THURSDAY-FRIDAY PERIOD...WILL ELECT TO ADD AN INITIAL MENTION OF THE LAKE EFFECT POTENTIAL TO THE HWO. LATER ON IN THE PERIOD...BOTH THE GFS AND ECMWF INDICATE THAT A DECENT CLIPPER-TYPE SYSTEM WILL ROUND THE BASE OF THE MEAN TROUGH AND WORK INTO OUR REGION SOMETIME BETWEEN FRIDAY NIGHT AND SATURDAY...THEN EXIT TO OUR EAST ON SUNDAY WITH A REINFORCING SHOT OF COLDER AND DRIER AIR FOLLOWING ITS PASSAGE. IN TERMS OF PRECIPITATION CHANCES...THIS FEATURE WILL BRING A MORE GENERAL CHANCE OF SNOW SHOWERS BACK INTO THE AREA FOR THE WEEKEND...WHILE ALSO INFLUENCING THE EVOLUTION OF THE LOW-LEVEL WIND FIELD...WHICH IN TURN WILL IMPACT THE ULTIMATE POSITION AND STRENGTH OF ANY LAKE SNOWS. GIVEN THE DISTANT DAY 6-7 TIME FRAME AND THE TYPICAL FORECAST UNCERTAINTY IN BOTH THE TIMING/TRACK/STRENGTH OF THIS FEATURE AND ITS EXACT INFLUENCE ON THE LOW LEVEL WIND FIELDS...FOR NOW HAVE JUST TRENDED POPS BACK TO THE BROADBRUSH LOW-MID CHANCE RANGE FOR NEXT WEEKEND. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... SNOW WITH AREAS OF SLEET AND FREEZING RAIN ARE NOW WORKING NORTH AND EAST ACROSS WESTERN NY. CIGS AND VIS ARE RUNNING IFR IN THESE AREAS WITH KROC ABOUT TO DROP TO IFR ONCE THE SNOW ARRIVE. KART IS VFR WITH SNOW AN HOUR OR TWO AWAY. THROUGH THIS MORNING EXPECT A WINTERY MIX TO AFFECT ALL TERMINALS WITH KART BEING THE LAST TO SEE THE ARRIVING SNOW. IFR WILL EVENTUALLY DEVELOP HERE TOO WHEN SNOW ARRIVES. GOING INTO THE AFTERNOON FOR WNY...THE AIR MASS WILL BECOME WARM ENOUGH DOWN TO THE SURFACE FOR A CHANGE OVER TO ALL RAIN. EXPECT THE LIQUID PRECIP TO TAPER OFF CLOSER TO THE EVENING AND TRANSITION TO DRIZZLE AND LIGHT FOG. PRECIPITATION WILL REMAIN IN A MIXED PHASE WELL INTO THE EVENING AND OVERNIGHT FOR KART. OUTLOOK... TUESDAY...MVFR WITH RAIN SHOWERS LIKELY. WEDNESDAY...MVFR/IFR WITH RAIN OR SNOW SHOWERS LIKELY. THURSDAY AND FRIDAY...MVFR/LOCALIZED IFR IN LAKE EFFECT SNOW SHOWERS. && .MARINE... A WARM FRONT IS LIFTING NORTH TOWARD THE LAKES EARLY THIS MORNING. AN ASSOCIATED LOW LEVEL JET WILL ALSO BRING SOME HIGHER WINDS TO LAKE ERIE WHERE A SMALL CRAFT ADVISORY HAS BEEN ISSUED. A WINTRY MIX OF PRECIPITATION WILL OCCUR OVER THE LAKES THROUGH TODAY AS THE WARMER AIR SLOWLY WORKS NORTHWARD. SOUTHERLY WINDS WILL BUILD WAVES ALONG THE NORTHERN LAKE SHORES TODAY THROUGH WEDNESDAY BUT EXPECT THESE TO GENERALLY REMAIN BELOW SMALL CRAFT CRITERIA. && .HYDROLOGY... WITH THE UPCOMING STRONG WARMUP...NORMALLY ONE WOULD EXPECT THE POTENTIAL FOR SOME ICE JAMS ON AREA CREEKS GIVEN THE TIME OF YEAR. THIS SAID...THIS WINTER HAS BEEN RELATIVELY MILD MUCH OF THE TIME... WITH THE BULK OF ANY ICE FORMATION ON CREEKS LIKELY COMING DURING OUR STRONG COLD SPELL OF THE PAST WEEK...WITH ANY ICE PROBABLY NOT YET REACHING THICKNESSES THAT WOULD POSE A SIGNIFICANT ICE JAM THREAT. THUS...WHILE THESE CANNOT BE AT ALL RULED OUT...AT THIS POINT WE DO NOT ANTICIPATE A STRONG THREAT OF ICE JAMS AND RESULTANT FLOODING ISSUES DURING THE UPCOMING WARMUP. WITH ICE JAMS LIKELY NOT A HUGE CONCERN...AT THIS POINT ANY HYDRO ISSUES THIS WEEK WILL PROBABLY HAVE TO INSTEAD BE DRIVEN BY A COMBINATION OF SNOWMELT AND RAINFALL. WITH OVERALL RAINFALL AMOUNTS LOOKING TO BE RELATIVELY LIGHT THROUGH TUESDAY... /GENERALLY ON THE ORDER OF A TENTH OR TWO TENTHS OF AN INCH PER EVERY 12 HOURS/...FEEL THAT ANY HYDRO CONCERNS SHOULD BE RELATIVELY MINIMAL THROUGH THAT TIME. AFTER THAT...THERE WILL BE THE POTENTIAL FOR SOMEWHAT HEAVIER SHOWERS ALONG AND IN ADVANCE OF A COLD FRONT TUESDAY AND WEDNESDAY...WHICH COULD LEAD TO A SOMEWHAT HIGHER POTENTIAL FOR LOCALIZED HYDRO ISSUES DURING THAT TIME FRAME. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ005>008. WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR NYZ003-004-013-014. WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NYZ001-002-010>012-019>021-085. MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST THIS EVENING FOR LEZ040-041. && $$ SYNOPSIS...SMITH NEAR TERM...SMITH SHORT TERM...WOOD LONG TERM...JJR AVIATION...SMITH MARINE...SMITH/WOOD HYDROLOGY...JJR
AREA FORECAST DISCUSSION
NWS BUFFALO NY
510 AM EST MON JAN 28 2013 .SYNOPSIS... WARMER TEMPERATURES WILL ARRIVE TODAY AS A WARM FRONT PUSHES NORTH ACROSS THE REGION. THIS WARM UP WILL BRING THE THREAT FOR A PERIOD OF MIXED SNOW, SLEET AND FREEZING RAIN AT THE ONSET BEFORE CHANGING TO ALL RAIN FROM SOUTHWEST TO NORTHEAST. WARM AND RAINY WEATHER WILL CONTINUE TUESDAY AND WEDNESDAY. MUCH COLDER WEATHER WILL RETURN WEDNESDAY NIGHT AS A COLD FRONT CROSSES THE LOWER GREAT LAKES SETTING THE STAGE FOR ACCUMULATING LAKE EFFECT SNOWS THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... THE MAIN FORECAST CONCERN FOR THIS MORNING WILL CONTINUE TO BE FOR MIXED PRECIPITATION ADVANCING NORTH AND EAST ACROSS WESTERN NEW YORK. AT 5 AM THE 09Z RAP 925MB 0C ISOTHERM HAS WORKED NORTH ACROSS FAR WESTERN NEW YORK AND IS SPREADING EAST INTO THE GENESEE RIVER VALLEY AND SOUTHERN FINGER LAKES WITH SURFACE TEMPS STILL IN THE 20S. THIS INDICATES THAT WARM AIR IS OVERSPREADING THE COLD DENSE AIR AT THE SURFACE WITH PRECIPITATION PHASE CHANGE OCCURRING AS IT FALLS FROM COLD TO WARM TO COLD AGAIN. BUFFALO RADAR REFLECTIVITY SHOWING SNOW HAS SPREAD NORTH AND EAST ACROSS THE SOUTHERN TIER...NIAGARA FRONTIER AND INTO THE GENESEE VALLEY. SNOW IS BEING REPORTED AT OLEAN NORTH TO BUFFALO...NIAGARA FALLS AND ROCHESTER WITH FREEZING RAIN AT DUNKIRK ON SURFACE OBSERVATIONS. AS WARM AIR INCREASES ALOFT...SLEET THEN FREEZING RAIN WILL MIX IN AND CHANGE OVER. A PEEK AT THE CORRELATION COEFFICIENT PRODUCT ON THE DUAL-POL INDICATED SLEET ALREADY MIXING IN EARLIER NEAR SALAMANCA AND OLEAN AND MOST RECENTLY IS MIXING IN OVER MUCH OF CHAUTAUQUA...CATTARAUGUS AND INTO ERIE COUNTY AS CC VALUES WERE RUNNING BETWEEN 0.85 AND 0.95 INDICATING HYDROMETEORS BECOMING MIS-SHAPED...ICING/SLEET OCCURRING. THE PRECIPITATION IS BEING FORCED BY A WARM FRONT LIFTING NORTH ACROSS THE OHIO VALLEY AND ALONG A 60 KT LOW LEVEL JET OVER INDIANA. THROUGH TODAY THE WARM FRONT WILL LIFT NORTH ACROSS NEW YORK WITH BOUNDARY LAYER TEMPS SLOWLY WARMING ABOVE FREEZING. IT STILL APPEARS THAT MOST LOCATIONS WILL RECEIVE ABOUT A 3 TO 5 HOUR PERIOD OF MIXED PRECIPITATION BEFORE CHANGING OVER TO RAIN. THE BEST CHANCE FOR THE LONGEST DURATION OF PROFILES SUPPORTIVE OF FREEZING PRECIPITATION WILL BE ACROSS EASTERN PORTIONS OF THE SOUTHERN TIER...FINGER LAKES AND EVENTUALLY NORTH COUNTRY. IT PROBABLY SHOULD BE NOTED THAT EVEN AFTER TEMPERATURES RISE ABOVE FREEZING...THE RECENT VERY COLD TEMPERATURES AND COLD GROUND MAY STILL SUPPORT AN INCREASED DURATION OF PRECIPITATION FREEZING ON SURFACES. MODEL QPF NOT OVERLY IMPRESSIVE WITH THIS EVENT WITH NEARLY ALL AVAILABLE GUIDANCE SUGGESTING AMOUNTS GENERALLY A HALF INCH OR LESS. SNOWFALL AMOUNTS GENERALLY IN THE 1-3 INCH RANGE FOR WESTERN NEW YORK WITH LONGER DURATION OF SNOW FOR THE NORTH COUNTRY LIKELY PRODUCING AS MUCH AS 3-5 INCHES THROUGH TODAY AND TONIGHT. ICE ACCUMULATIONS WILL HOLD TO A TENTH OF AN INCH OR LESS FOR THE MAJORITY OF LOCATIONS BUT SECTIONS OF THE SOUTHERN FINGER LAKES AND UPPER GENESEE VALLEY COULD SEE UPWARDS OF A QUARTER INCH ESPECIALLY IN COLDER VALLEYS. DUE TO THE ANTICIPATED FREEZING PRECIPITATION ON TOP OF THE INITIAL MINOR SNOWFALL AMOUNTS...A WINTER WEATHER ADVISORY REMAINS IN EFFECT TODAY FOR THE ENTIRE AREA. GOING INTO THE AFTERNOON EVENTUALLY THE WARMER AIR BUILDS DOWN TO THE SURFACE AND PROFILES WILL SUPPORT JUST PLAIN RAIN. THE ENDING TIMES OF THESE ADVISORIES CORRELATE WITH WHEN WE EXPECT PRECIPITATION TO BE ALL RAIN. HIGHS TODAY WILL REACH TO AROUND 40 FOR MUCH OF WNY WITH 30S AND EVEN UPPER 20S IN THE VALLEYS OF THE NORTH COUNTY WHERE LONGER DURATION OF SNOW AND MIXED PRECIP IS EXPECTED. THE LOW LEVEL JET HELPING TO DRIVE THE WEATHER TODAY WILL ALSO CREATE SOME GUSTY WINDS ACROSS THE SOUTHERN TIER DURING THE LATE MORNING AND AFTERNOON BUT WILL STAY BELOW WIND ADVISORY CRITERIA. FOR TONIGHT THE CENTER OF THE STORM SYSTEM WILL LIFT FROM NEAR MICHIGAN EASTWARD AND ACROSS OUR FORECAST AREA WITH THE WARM FRONT ALSO LIFTING NORTH AND EAST. EXPECT PRECIPITATION TYPE FOR ALL OF WESTERN AND LOWER CENTRAL NY TO BE RAIN WITH SNOW CONTINUING ACROSS THE NORTH COUNTRY. EVENTUALLY THE WARM NOSE WILL SPREAD OVER EASTERN LAKE ONTARIO COUNTIES AS WELL WITH SLEET AND FREEZING RAIN MIXED PRECIP. SURFACE TEMPS WILL REMAIN NEARLY STEADY OVERNIGHT IN THE UPPER 30S TO LOWER 40S ACROSS WESTERN NY AND EVENTUALLY INCHING ABOVE FREEZING ACROSS THE NORTH COUNTY. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... WET AND VERY MILD WEATHER WILL CHARACTERIZE THE INITIAL PORTION OF THIS PERIOD AS WARM AIR SURGES NORTHWARDS ACROSS THE REGION AHEAD OF AN APPROACHING COLD FRONT THAT WILL MARCH EASTWARDS ACROSS THE GREAT LAKES WEDNESDAY NIGHT...CROSSING WESTERN AND CENTRAL NEW YORK WHILE USHERING IN THE RETURN OF WINTER ALONG WITH THE LIKELIHOOD OF SIGNIFICANT LAKE EFFECT SNOWS FOR THE LATTER HALF OF THE WEEK. THE BULK OF THE INITIAL WAVE OF PRECIPITATION ASSOCIATED WITH THE WARM FRONT CURRENTLY MOVING INTO WESTERN NEW YORK WILL HAVE PUSH EAST ACROSS NEW ENGLAND BY TUESDAY MORNING...HOWEVER A LINGERING SURFACE TROUGH ALONG WITH PLENTY OF MOISTURE REMAINING IN PLACE SHOULD ALLOW FOR AT LEAST A CHANCE OF SHOWERS TO START OUT THE DAY WITH POPS RAMPING UP ONCE AGAIN BY THE AFTERNOON AS ANOTHER WARM FRONT LIFTS NORTH ACROSS THE REGION WITH DEEPER MOISTURE RIDING OVER THE TOP OF AN UPPER LEVEL RIDGE CROSSING THE OHIO VALLEY AND LOWER GREAT LAKES. THIS WARM FRONTAL BOUNDARY MARKS THE LEADING EDGE OF AN EXCEPTIONALLY WARM AIRMASS WITH 850MB TEMPERATURES AS HIGH AS +10C ADVECTING NORTH INTO WESTERN AND CENTRAL NEW YORK. THIS AIRMASS WILL MAKE IT FEEL MORE LIKE LATE MARCH/EARLY APRIL AS TEMPERATURES RISE INTO THE LOWER 50S FROM THE GENESEE VALLEY WEST WHILE AREAS EAST WILL STAY IN THE 40S. THE WARMUP WILL CONTINUE UNABATED TUESDAY NIGHT WITH ANY DIURNAL COOLING BEING OFFSET BY THE CONTINUED WARM ADVECTION ALONG WITH CLOUD COVER/ONGOING PRECIP AS THE WARM FRONTAL BAND LIFTS NORTH AND EAST ACROSS THE AREA. EXTENSIVE ISENTROPIC LIFTING ALONG THIS FRONTAL BAND WILL RESULT IN QPF APPROACHING HALF AN INCH OVERNIGHT...HOWEVER THERE ARE DISRCREPANCIES AMONG THE MODELS ON THE EXACT PLACEMENT OF THE FRONT AND ASSOCIATED AXIS OF HEAVIEST RAIN. HOWEVER AT THIS POINT IT APPEARS THAT GREATEST POPS WILL BE NORTH OF THE THRUWAY WHILE AREAS SOUTH MAY STAY IN THE DRIER WARM SECTOR. TEMPERATURES ACROSS THE NORTH COUNTRY WILL GRADUALLY WARM THROUGH THE NIGHT INTO THE LOWER 50S WHILE THE REST OF THE FORECAST AREA WILL SLOWLY CLIMB INTO THE LOW TO MID 50S BY DAYBREAK WEDNESDAY. ANOTHER ISSUE ASSOCIATED WITH THE ADVECTION OF WARM MOIST AIR NORTHWARDS ACROSS THE COLD LAKES WILL BE FOG AND HAVE UPDATED GRIDS TO INCLUDE THIS. AS THE WINDS WILL BE RELATIVELY BREEZY OUT OF THE SOUTH...WILL ASSUME THAT MOST OF THE LAND AREAS OF THE FORECAST AREA SHOULD STAY FOG FREE...HOWEVER THE NIAGARA FRONTIER FROM DOWNTOWN BUFFALO NORTH ACROSS NIAGARA COUNTY MAY BE THE RECIPIENTS OF ADVCETION FOG OFF LAKE ERIE IF THERE IS ANY SOUTHWESTERLY COMPONENT TO THE WINDS. WE WILL SEE A VERY BALMY TO WEDNESDAY AS THE AREA WILL BE FIRMLY IN THE WARM SECTOR OF A BROAD AREA OF LOW PRESSURE EXTENDING ACROSS THE MIDWEST AND CENTRAL GREAT LAKES. THERE ARE SIGNIFICANT DIFFERENCES BETWEEN THE GFS/NAM WHICH RAPIDLY DEVELOP A VERY DEEP LOW OVER THE CENTRAL GREAT LAKES FROM A WAVE MOVING UP THE FRONT MARKING THE BOUDNARY BETWEEN THE WARM AIR OVER THE EASTERN U.S. AND A SUB-ARCTIC BLAST OF COLD AIR DROPPING ACROSS THE NORTHERN PLAINS OUT OF CANADA. ON THE OTHER HAND THE ECMWF FEATURES A WEAKER SERIES OF WAVES THAT WORK THEIR WAY ALONG THE SLOWER MOVING FRONTAL BOUDNARY...WITH NO SINGLE LOW BECOMING DOMINANT. THIS HAS A SIGNIFICANT IMPACT ON THE WIND FORECAST FOR OUR AREA AS A NAM/GFS SOLUTION WITH THE DEEP LOW TRACKING OUT THE CENTRAL LAKES COULD MEAN A SIGIFICANT WIND EVENT ACROSS THE AREA...WHILST THE ECMWF SOLUTION WOULD BE MUCH MORE BENIGN. GIVEN THE UNCERTAINTY...THE CURRENT FORECAST WILL LEAN MORE TOWARDS THE ECMWF SOLUTION...WHICH ALSO PRESERVES CONTINUITY WITH THE PREVIOUS FORECAST. THUS...STILL EXPECT A FRONTAL PASSAGE LATE WEDENSDAY AFTERNOON/WEDNESDAY EVENING WITH BREEZY...BUT NOT DAMAGING...SOUTH WINDS VEERING TO THE SOUTHWEST AND EVENTUALLY TO THE WEST AS TEMPERATURES FALL FROM THE MID 50S EARLY WEDNESDAY TO THE UPPER 20S/LOWER 30S WEDNESDAY NIGHT. ACCOMPANYING THIS FRONTAL PASSAGE WILL BE ANOTHER DECENT SOAKING RAIN WITH A QUARTER TO A HALF INCH OF QPF POSSIBLE...DEPENDING ON HOW FAST THE FRONT MOVES THROUGH. BY EARLY THURSDAY MORNING...WE SHOULD SEE TEMPERATURES COOL TO THE POINT THAT LAKE EFFECT SHOWERS SHOULD BEGIN TO DEVELOP... && .LONG TERM /THURSDAY THROUGH SUNDAY/... FOLLOWING THE PASSAGE OF THE MIDWEEK COLD FRONT...THE MEDIUM RANGE GUIDANCE REMAINS IN EXCELLENT AGREEMENT THAT BROAD UPPER TROUGHING WILL BECOME RE-ESTABLISHED ACROSS THE GREAT LAKES AND NORTHEAST THURSDAY AND FRIDAY...WITH TEMPERATURES TUMBLING BACK TO WELL BELOW AVERAGE AS PROGRESSIVELY COLDER AIR FLOODS EAST ACROSS THE GREAT LAKES. WHILE THE INCOMING COLDER AIRMASS DOES NOT LOOK TO BE NEARLY QUITE AS COLD AS THE ONE THAT AFFECTED OUR REGION FOR MUCH OF LAST WEEK...850 MB TEMPS STILL LOOK TO DROP TO THE VICINITY OF -18C TO -20C...WHICH WILL BE PLENTY COLD ENOUGH TO RESULT IN DAYTIME HIGHS FALLING BACK TO AROUND 20 BY FRIDAY...AND THE DEVELOPMENT OF ANOTHER ROUND OF POTENTIALLY SIGNIFICANT LAKE EFFECT SNOWS DOWNWIND OF THE LAKES. WHILE IT IS STILL TOO EARLY TO DEFINITIVELY PIN DOWN EXACTLY WHICH AREAS THE LAKE SNOWS MIGHT FOCUS ON...BOTH THE GFS/ECMWF CONTINUE TO SUGGEST THAT THE LAKE EFFECT ACTIVITY WILL DEVELOP IN A WESTERLY FLOW REGIME LATER WEDNESDAY NIGHT/EARLY THURSDAY...BEFORE INTENSIFYING OVER TIME THURSDAY AS AN INITIALLY DRY AIRMASS MOISTENS IN ADVANCE OF AN APPROACHING SECONDARY SURFACE TROUGH. AFTER THAT TIME...SOME DISAGREEMENT EMERGES WITH THE ECMWF PUSHING THE SURFACE TROUGH THROUGH LATER THURSDAY NIGHT/EARLY FRIDAY WITH THE LOW LEVEL FLOW GOING MORE NORTHWESTERLY ON FRIDAY FOLLOWING ITS PASSAGE... WHILE THE GFS ESSENTIALLY WASHES OUT THE TROUGH AND KEEPS MORE OF A WESTERLY FLOW IN PLACE THROUGH FRIDAY. DOWNWIND OF LAKE ERIE...ALL OF THIS WOULD SUGGEST THE STRONGEST AND MOST ORGANIZED LAKE SNOWS INITIALLY DEVELOPING ACROSS THE WESTERN SOUTHERN TIER AND SOUTHERN ERIE AND WYOMING COUNTIES LATER WEDNESDAY NIGHT INTO THURSDAY...THEN EITHER LINGERING PRETTY MUCH IN PLACE THROUGH FRIDAY...OR SHIFTING A BIT FURTHER SOUTH TO AREAS SOUTHEAST OF THE LAKE DEPENDING UPON WHETHER THERE ACTUALLY IS A SECONDARY TROUGH PASSAGE AND ASSOCIATED WIND SHIFT. SIMILARLY...THE LAKE ONTARIO LAKE SNOWS WOULD LIKELY DEVELOP ACROSS THE TUG HILL REGION WEDNESDAY NIGHT INTO THURSDAY...THEN EITHER REMAIN IN PLACE THROUGH FRIDAY OR MIGRATE SOUTHWARD TO AREAS SOUTHEAST OF THE LAKE. CONSIDERING THE ABOVE...WILL INDICATE SOME BROAD AREAS OF HIGHER PRECIPITATION CHANCES EAST OF THE LAKES ON THURSDAY...THEN EXPAND THESE TO COVER AREAS BOTH EAST AND SOUTHEAST OF THE LAKES THURSDAY NIGHT AND FRIDAY GIVEN THE INCREASING UNCERTAINTY IN WIND DIRECTION AND RESULTANT BAND PLACEMENT DURING THESE TWO PERIODS. IN TERMS OF ACTUAL POP VALUES...WILL INCREASE POPS TO LOW LIKELY WITHIN THE MORE FAVORED LAKE EFFECT REGIONS ON THURSDAY GIVEN CONTINUED GOOD AGREEMENT DURING THIS TIME FRAME...BEFORE DROPPING THESE BACK TO HIGH CHANCE FOR THURSDAY NIGHT AND FRIDAY GIVEN THE INCREASING FORECAST UNCERTAINTY. OUTSIDE OF THE MORE FAVORED LAKE EFFECT AREAS...WILL KEEP SOMEWHAT LOWER CHANCE POPS IN PLAY BOTH TO COVER THE APPROACH AND POSSIBLE PASSAGE OF THE SECONDARY SURFACE TROUGH... AND TO ALSO REFLECT THE INHERENT UNCERTAINTY IN DELINEATING SPECIFIC AREAS OF LAKE EFFECT THIS FAR OUT. NEEDLESS TO SAY...IT IS STILL WAY TOO EARLY TO EVEN CONSIDER ANY FLAGS FOR THIS PERIOD JUST YET...THOUGH GIVEN THE CONSISTENTLY FAVORABLE SYNOPTIC PATTERN AND THERMODYNAMIC ENVIRONMENT SEEN IN THE GUIDANCE IN THE THURSDAY-FRIDAY PERIOD...WILL ELECT TO ADD AN INITIAL MENTION OF THE LAKE EFFECT POTENTIAL TO THE HWO. LATER ON IN THE PERIOD...BOTH THE GFS AND ECMWF INDICATE THAT A DECENT CLIPPER-TYPE SYSTEM WILL ROUND THE BASE OF THE MEAN TROUGH AND WORK INTO OUR REGION SOMETIME BETWEEN FRIDAY NIGHT AND SATURDAY...THEN EXIT TO OUR EAST ON SUNDAY WITH A REINFORCING SHOT OF COLDER AND DRIER AIR FOLLOWING ITS PASSAGE. IN TERMS OF PRECIPITATION CHANCES...THIS FEATURE WILL BRING A MORE GENERAL CHANCE OF SNOW SHOWERS BACK INTO THE AREA FOR THE WEEKEND...WHILE ALSO INFLUENCING THE EVOLUTION OF THE LOW-LEVEL WIND FIELD...WHICH IN TURN WILL IMPACT THE ULTIMATE POSITION AND STRENGTH OF ANY LAKE SNOWS. GIVEN THE DISTANT DAY 6-7 TIME FRAME AND THE TYPICAL FORECAST UNCERTAINTY IN BOTH THE TIMING/TRACK/STRENGTH OF THIS FEATURE AND ITS EXACT INFLUENCE ON THE LOW LEVEL WIND FIELDS...FOR NOW HAVE JUST TRENDED POPS BACK TO THE BROADBRUSH LOW-MID CHANCE RANGE FOR NEXT WEEKEND. && .AVIATION /10Z MONDAY THROUGH FRIDAY/... SNOW WITH AREAS OF SLEET AND FREEZING RAIN ARE NOW WORKING NORTH ACROSS THE SOUTHERN TIER AND NIAGARA FRONTIER. CIGS AND VIS ARE RUNNING IFR IN THESE AREAS WITH STILL VFR FOR KROC AND KART AS PRECIP HAS NOT STARTED YET THERE. FROM NOW THROUGH THIS MORNING EXPECT WINTRY MIX TO AFFECT ALL TERMINALS WEST OF SYRACUSE. NOT EXPECTING SNOW FOR KART UNTIL AFTER NOONTIME. IFR WILL EVENTUALLY DEVELOP HERE. GOING INTO THE AFTERNOON FOR WNY...THE AIR MASS WILL BECOME WARM ENOUGH DOWN TO THE SURFACE FOR A CHANGE OVER TO ALL RAIN. EXPECT THE LIQUID PRECIP TO TAPER OFF DURING THE LATE AFTERNOON INTO THE EVENING AND TRANSITION TO DRIZZLE AND LIGHT FOG. PRECIPITATION WILL REMAIN IN A MIXED PHASE WELL INTO THE EVENING AND OVERNIGHT FOR KART. OUTLOOK... TUESDAY...MVFR WITH RAIN SHOWERS LIKELY. WEDNESDAY...MVFR/IFR WITH RAIN OR SNOW SHOWERS LIKELY. THURSDAY AND FRIDAY...MVFR/LOCALIZED IFR IN LAKE EFFECT SNOW SHOWERS. && .MARINE... A WARM FRONT IS LIFTING NORTH TOWARD THE LAKES EARLY THIS MORNING. AN ASSOCIATED LOW LEVEL JET WILL ALSO BRING SOME HIGHER WINDS TO LAKE ERIE WHERE A SMALL CRAFT ADVISORY HAS BEEN ISSUED. A WINTRY MIX OF PRECIPITATION WILL OCCUR OVER THE LAKES THROUGH TODAY AS THE WARMER AIR SLOWLY WORKS NORTHWARD. SOUTHERLY WINDS WILL BUILD WAVES ALONG THE NORTHERN LAKE SHORES TODAY THROUGH WEDNESDAY BUT EXPECT THESE TO GENERALLY REMAIN BELOW SMALL CRAFT CRITERIA. && .HYDROLOGY... WITH THE UPCOMING STRONG WARMUP...NORMALLY ONE WOULD EXPECT THE POTENTIAL FOR SOME ICE JAMS ON AREA CREEKS GIVEN THE TIME OF YEAR. THIS SAID...THIS WINTER HAS BEEN RELATIVELY MILD MUCH OF THE TIME... WITH THE BULK OF ANY ICE FORMATION ON CREEKS LIKELY COMING DURING OUR STRONG COLD SPELL OF THE PAST WEEK...WITH ANY ICE PROBABLY NOT YET REACHING THICKNESSES THAT WOULD POSE A SIGNIFICANT ICE JAM THREAT. THUS...WHILE THESE CANNOT BE AT ALL RULED OUT...AT THIS POINT WE DO NOT ANTICIPATE A STRONG THREAT OF ICE JAMS AND RESULTANT FLOODING ISSUES DURING THE UPCOMING WARMUP. WITH ICE JAMS LIKELY NOT A HUGE CONCERN...AT THIS POINT ANY HYDRO ISSUES THIS WEEK WILL PROBABLY HAVE TO INSTEAD BE DRIVEN BY A COMBINATION OF SNOWMELT AND RAINFALL. WITH OVERALL RAINFALL AMOUNTS LOOKING TO BE RELATIVELY LIGHT THROUGH TUESDAY... /GENERALLY ON THE ORDER OF A TENTH OR TWO TENTHS OF AN INCH PER EVERY 12 HOURS/...FEEL THAT ANY HYDRO CONCERNS SHOULD BE RELATIVELY MINIMAL THROUGH THAT TIME. AFTER THAT...THERE WILL BE THE POTENTIAL FOR SOMEWHAT HEAVIER SHOWERS ALONG AND IN ADVANCE OF A COLD FRONT TUESDAY AND WEDNESDAY...WHICH COULD LEAD TO A SOMEWHAT HIGHER POTENTIAL FOR LOCALIZED HYDRO ISSUES DURING THAT TIME FRAME. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ005>008. WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR NYZ003-004-013-014. WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NYZ001-002-010>012-019>021-085. MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST THIS EVENING FOR LEZ040-041. && $$ SYNOPSIS...SMITH NEAR TERM...SMITH SHORT TERM...WOOD LONG TERM...JJR AVIATION...SMITH MARINE...SMITH/WOOD HYDROLOGY...JJR
AREA FORECAST DISCUSSION
NWS BUFFALO NY
206 AM EST MON JAN 28 2013 .SYNOPSIS... WARMER TEMPERATURES WILL ARRIVE MONDAY AS A WARM FRONT PUSHES NORTH ACROSS THE REGION. THIS WARMUP WILL BRING THE THREAT FOR A PERIOD OF MIXED SNOW...SLEET AND FREEZING RAIN AT THE ONSET BEFORE CHANGING TO ALL RAIN FROM WEST TO EAST THROUGH MONDAY. WARM AND RAINY WEATHER WILL CONTINUE TUESDAY AND WEDNESDAY. MUCH COLDER WEATHER WILL RETURN WEDNESDAY NIGHT AS A COLD FRONT CROSSES THE LOWER GREAT LAKES SETTING THE STAGE FOR ACCUMULATING LAKE EFFECT SNOWS THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH TODAY/... AT 145 AM...MAIN FORECAST CONCERN FOR THE NEAR TERM PERIOD WILL CONTINUE TO BE FOR MIXED PRECIPITATION ADVANCING NORTH ACROSS NEW YORK THIS MORNING. AT 1 AM THE 05Z RAP 925MB 0C ISOTHERM WAS ENTERING CROSSING THE BORDER FROM NORTHWEST PA INTO CHAUTAUQUA COUNTY WITH ZR ALREADY BEING REPORTED IN KERI. BUFFALO RADAR REFLECTIVITY SHOWING SNOW IS SPREADING NORTH AND EAST INTO THE SOUTHERN TIER. STILL EXPECT PRECIPITATION TO START OUT AS SNOW THEN AS WARM AIR INCREASES ALOFT A CHANGE TO SLEET THEN FREEZING RAIN WILL OCCUR. A PEEK AT THE CORRELATION COEFFICIENT PRODUCT ON THE DUAL-POL INDICATED SLEET ALREADY MIXING IN NEAR SALAMANCA AND OLEAN AS CC VALUES WERE RUNNING BETWEEN 0.85 AND 0.95 INDICATING HYDROMETEORS BECOMING MIS-SHAPED...ICING OCCURRING. THE PRECIPITATION IS BEING FORCED BY A WARM FRONT LIFTING NORTH ACROSS PA AND ALONG A 60 KT LOW LEVEL JET OVER INDIANA. IT STILL APPEARS THAT MOST LOCATIONS WILL RECEIVE ABOUT A 3 TO 5 HOUR PERIOD OF MIXED PRECIPITATION BEFORE CHANGING OVER TO RAIN. THE BEST CHANCE FOR THE LONGEST DURATION OF PROFILES SUPPORTIVE OF FREEZING PRECIPITATION WILL BE ACROSS EASTERN PORTIONS OF THE SOUTHERN TIER...FINGER LAKES AND NORTH COUNTRY. IT PROBABLY SHOULD BE NOTED THAT EVEN AFTER TEMPERATURES RISE ABOVE FREEZING...THE RECENT VERY COLD TEMPERATURES AND COLD GROUND MAY STILL SUPPORT AN INCREASED DURATION OF PRECIPITATION FREEZING ON SURFACES. MODEL QPF NOT OVERLY IMPRESSIVE WITH THIS EVENT WITH NEARLY ALL AVAILABLE GUIDANCE SUGGESTING AMOUNTS GENERALLY A HALF INCH OR LESS. SNOWFALL AMOUNTS GENERALLY IN THE 1-3 INCH RANGE WITH THE HIGHER END AMOUNTS ACROSS THE NORTH COUNTRY. ICE ACCUMULATIONS WILL HOLD TO A TENTH OF AN INCH OR LESS. DUE TO THE ANTICIPATED FREEZING PRECIPITATION ON TOP OF THE INITIAL MINOR SNOWFALL AMOUNTS...A WINTER WEATHER ADVISORY HAS BEEN ISSUED FOR THE ENTIRE AREA. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... MONDAY NIGHT...THE WARM FRONTAL BOUNDARY WILL PUSH INTO THE NORTH COUNTRY...WITH PRECIPITATION DIMINISHING FROM SOUTHWEST TO NORTHEAST AS THE INITIAL WEAK WAVE OF LOW PRESSURE AND ASSOCIATED SWATH OF STRONGER WARM ADVECTION SLIDES OFF INTO EASTERN NEW YORK AND NEW ENGLAND. ACROSS THE NORTH COUNTRY...CONTINUED WARMING BOTH AT THE SURFACE AND ALOFT WILL RESULT IN A MIX OF SNOW...SLEET...AND FREEZING RAIN GRADUALLY TRANSITIONING OVER TO ALL LIQUID...THOUGH ANY ICING WILL LIKELY REMAIN UNDER A TENTH OF AN INCH GIVEN THE OVERALL LIGHTENING/DIMINISHING TREND OF THE PRECIP. SOUTH OF THE WARM FRONT...TEMPS WILL REMAIN WARM ENOUGH FOR ANY LEFTOVER PRECIPITATION TO FALL ENTIRELY IN THE FORM OF PLAIN LIQUID SOUTH OF LAKE ONTARIO...WITH STRONG DRYING ALOFT PROBABLY RESULTING IN ALL OF THIS DEVOLVING INTO AREAS OF LEFTOVER SPOTTY LIGHT RAIN AND OR DRIZZLE. AS FOR TEMPERATURES...THE ONGOING WARM ADVECTION PATTERN WILL BE STRONG ENOUGH TO OFFSET ANY NOCTURNAL COOLING...RESULTING IN TEMPS WARMING SLIGHTLY INTO THE LOWER 40S IN MOST AREAS SOUTH OF LAKE ONTARIO...WHILE READINGS EAST OF THE LAKE MORE ONLY MORE SLOWLY RISE OR REMAIN STEADY IN THE LOWER TO MID 30S. TUESDAY WILL START OFF WITH WEAK SURFACE TROUGHING...THE REMNANTS OF MONDAY`S WARM FRONT...LINGERING ACROSS NEW YORK STATE DURING THE MORNING. COUPLED WITH LINGERING LOW LEVEL MOISTURE...THIS WILL LEAD TO SOME MORE SPOTTY LIGHT SHOWERS OR AREAS OF LIGHT RAIN/DRIZZLE... FOR WHICH CHANCE POPS WILL REMAIN IN PLAY. AFTER THAT TIME...ANOTHER COMPLEX LOW PRESSURE SYSTEM WILL LIFT NORTHEASTWARD FROM THE OHIO VALLEY INTO THE CENTRAL GREAT LAKES AND SOUTHERN ONTARIO...BRINGING MULTIPLE NOTEWORTHY SURGES OF WARM AIR ADVECTION FOR THE AFTERNOON AND EVENING ALONG WITH A RENEWED THREAT FOR MORE WIDESPREAD SHOWER ACTIVITY. IN THE FORECAST...HAVE REFLECTED THIS WITH A RETURN TO LIKELY POPS FOR TUESDAY AFTERNOON AND EVENING...BEFORE SOME SEMBLANCE OF A RELATIVE LULL ACROSS PORTIONS OF THE AREA LATER IN THE NIGHT AS THE MAIN SWATH OF WARM ADVECTION LIFTS OFF TO OUR NORTH. WITH RESPECT TO TEMPS...THE CONTINUED STRONG WARM AIR ADVECTION PATTERN WILL ALLOW FOR READINGS TO CLIMB INTO THE UPPER 40S TO LOWER 50S SOUTH OF LAKE ONTARIO ON TUESDAY...WHILE READINGS EAST OF THE LAKE SEE HIGHS IN THE LOWER TO MID 40S. AS WILL BE THE CASE WITH MONDAY NIGHT...EXPECT TEMPS TO AGAIN REMAIN RELATIVELY STEADY OR SLOWLY RISE THROUGH TUESDAY NIGHT GIVEN THE CONTINUED WARM AIR ADVECTION PATTERN. ON WEDNESDAY...THE COMPLEX LOW TO OUR WEST WILL LIFT OUT INTO ONTARIO AND QUEBEC AND SWING ITS ASSOCIATED COLD FRONT EAST ACROSS OUR REGION...WITH THE 12Z GUIDANCE SUITE CONVERGING ON A GENERAL AFTERNOON TIMING TO THE FROPA. IN ADVANCE OF THE BOUNDARY...TEMPS WILL PEAK IN THE 50S IN THE MORNING...BEFORE STARTING TO DROP OFF AS ONE OR MORE BANDS OF PREFRONTAL/FRONTAL SHOWERS WORK ACROSS THE REGION...AND THEN FALL MORE QUICKLY AS COLD ADVECTION BEGINS FOLLOWING THE COLD FRONTAL PASSAGE. THIS SAID...WE STILL EXPECT CONDITIONS TO REMAIN WARM ENOUGH FOR ALL OF THE PRECIP TO FALL IN THE FORM OF RAIN SHOWERS DURING WEDNESDAY...BEFORE MIXING WITH AND EVENTUALLY CHANGING TO SNOW SHOWERS AS IT TAPERS OFF WEDNESDAY NIGHT. DEPENDING UPON THE ACTUAL STRENGTH OF THE LOW...IT SHOULD BE NOTED THAT THERE COULD ALSO BE SOME WIND CONCERNS TUESDAY NIGHT INTO WEDNESDAY. THE 12Z GFS/NAM/GEM HAVE ALL TRENDED TOWARDS A MUCH STRONGER MAIN LOW CENTER OVER THE PAST COUPLE OF RUNS...WITH ALL OF THESE SOLUTIONS DEEPENING THE LOW TO 975 MB AS IT WORKS INTO SOUTHERN ONTARIO BY LATE WEDNESDAY...WHILE THE MORE CONSISTENT AND USUALLY MORE RELIABLE ECMWF REMAINS WEAKER WITH A MUCH MORE ELONGATED LOW WEDNESDAY AFTERNOON AND EVENING. AS A CONSEQUENCE... THE STRONGER MODELS ALSO HAVE A MUCH STRONGER WIND FIELD SURROUNDING THE LOW...WITH THE NAM/GFS RESPECTIVELY FORECASTING 90+/80+ KT SOUTHERLY LOW LEVEL JETS IN ADVANCE OF THE LOW TUESDAY NIGHT INTO WEDNESDAY... WITH THE GFS THEN ALSO HANGING BACK SOME OF THESE STRONGER WINDS BACK BEHIND THE COLD FRONTAL PASSAGE WEDNESDAY AFTERNOON AND EVENING. WERE THESE STRONGER SOLUTIONS TO VERIFY... THEY WOULD POSE A THREAT OF STRONG WINDS IN BOTH TYPICALLY FAVORED DOWNSLOPE FLOW REGIONS AND AREAS OF HIGHER TERRAIN TUESDAY NIGHT INTO WEDNESDAY... WITH THE GFS THEN ALSO SUGGESTING AT LEAST A SMALL WINDOW FOR SOME MORE WIDESPREAD STRONG WINDS FOLLOWING THE COLD FROPA LATER WEDNESDAY AFTERNOON AND EVENING. WILL NOT MENTION THIS POTENTIAL IN THE HWO JUST YET GIVEN THAT WE HAVE ONLY SEEN ONE MODEL CYCLE`S WORTH OF STRONGER SOLUTIONS...AND IN ONLY SOME OF THE MODELS AT THAT...HOWEVER THIS POSSIBILITY WILL NEED TO BE CLOSELY WATCHED OVER THE NEXT FEW DAYS. && .LONG TERM /THURSDAY THROUGH SUNDAY/... FOLLOWING THE PASSAGE OF THE MIDWEEK COLD FRONT...THE MEDIUM RANGE GUIDANCE REMAINS IN EXCELLENT AGREEMENT THAT BROAD UPPER TROUGHING WILL BECOME RE-ESTABLISHED ACROSS THE GREAT LAKES AND NORTHEAST THURSDAY AND FRIDAY...WITH TEMPERATURES TUMBLING BACK TO WELL BELOW AVERAGE AS PROGRESSIVELY COLDER AIR FLOODS EAST ACROSS THE GREAT LAKES. WHILE THE INCOMING COLDER AIRMASS DOES NOT LOOK TO BE NEARLY QUITE AS COLD AS THE ONE THAT AFFECTED OUR REGION FOR MUCH OF LAST WEEK...850 MB TEMPS STILL LOOK TO DROP TO THE VICINITY OF -18C TO -20C...WHICH WILL BE PLENTY COLD ENOUGH TO RESULT IN DAYTIME HIGHS FALLING BACK TO AROUND 20 BY FRIDAY...AND THE DEVELOPMENT OF ANOTHER ROUND OF POTENTIALLY SIGNIFICANT LAKE EFFECT SNOWS DOWNWIND OF THE LAKES. WHILE IT IS STILL TOO EARLY TO DEFINITIVELY PIN DOWN EXACTLY WHICH AREAS THE LAKE SNOWS MIGHT FOCUS ON...BOTH THE GFS/ECMWF CONTINUE TO SUGGEST THAT THE LAKE EFFECT ACTIVITY WILL DEVELOP IN A WESTERLY FLOW REGIME LATER WEDNESDAY NIGHT/EARLY THURSDAY...BEFORE INTENSIFYING OVER TIME THURSDAY AS AN INITIALLY DRY AIRMASS MOISTENS IN ADVANCE OF AN APPROACHING SECONDARY SURFACE TROUGH. AFTER THAT TIME...SOME DISAGREEMENT EMERGES WITH THE ECMWF PUSHING THE SURFACE TROUGH THROUGH LATER THURSDAY NIGHT/EARLY FRIDAY WITH THE LOW LEVEL FLOW GOING MORE NORTHWESTERLY ON FRIDAY FOLLOWING ITS PASSAGE... WHILE THE GFS ESSENTIALLY WASHES OUT THE TROUGH AND KEEPS MORE OF A WESTERLY FLOW IN PLACE THROUGH FRIDAY. DOWNWIND OF LAKE ERIE...ALL OF THIS WOULD SUGGEST THE STRONGEST AND MOST ORGANIZED LAKE SNOWS INITIALLY DEVELOPING ACROSS THE WESTERN SOUTHERN TIER AND SOUTHERN ERIE AND WYOMING COUNTIES LATER WEDNESDAY NIGHT INTO THURSDAY...THEN EITHER LINGERING PRETTY MUCH IN PLACE THROUGH FRIDAY...OR SHIFTING A BIT FURTHER SOUTH TO AREAS SOUTHEAST OF THE LAKE DEPENDING UPON WHETHER THERE ACTUALLY IS A SECONDARY TROUGH PASSAGE AND ASSOCIATED WIND SHIFT. SIMILARLY...THE LAKE ONTARIO LAKE SNOWS WOULD LIKELY DEVELOP ACROSS THE TUG HILL REGION WEDNESDAY NIGHT INTO THURSDAY...THEN EITHER REMAIN IN PLACE THROUGH FRIDAY OR MIGRATE SOUTHWARD TO AREAS SOUTHEAST OF THE LAKE. CONSIDERING THE ABOVE...WILL INDICATE SOME BROAD AREAS OF HIGHER PRECIPITATION CHANCES EAST OF THE LAKES ON THURSDAY...THEN EXPAND THESE TO COVER AREAS BOTH EAST AND SOUTHEAST OF THE LAKES THURSDAY NIGHT AND FRIDAY GIVEN THE INCREASING UNCERTAINTY IN WIND DIRECTION AND RESULTANT BAND PLACEMENT DURING THESE TWO PERIODS. IN TERMS OF ACTUAL POP VALUES...WILL INCREASE POPS TO LOW LIKELY WITHIN THE MORE FAVORED LAKE EFFECT REGIONS ON THURSDAY GIVEN CONTINUED GOOD AGREEMENT DURING THIS TIME FRAME...BEFORE DROPPING THESE BACK TO HIGH CHANCE FOR THURSDAY NIGHT AND FRIDAY GIVEN THE INCREASING FORECAST UNCERTAINTY. OUTSIDE OF THE MORE FAVORED LAKE EFFECT AREAS...WILL KEEP SOMEWHAT LOWER CHANCE POPS IN PLAY BOTH TO COVER THE APPROACH AND POSSIBLE PASSAGE OF THE SECONDARY SURFACE TROUGH... AND TO ALSO REFLECT THE INHERENT UNCERTAINTY IN DELINEATING SPECIFIC AREAS OF LAKE EFFECT THIS FAR OUT. NEEDLESS TO SAY...IT IS STILL WAY TOO EARLY TO EVEN CONSIDER ANY FLAGS FOR THIS PERIOD JUST YET...THOUGH GIVEN THE CONSISTENTLY FAVORABLE SYNOPTIC PATTERN AND THERMODYNAMIC ENVIRONMENT SEEN IN THE GUIDANCE IN THE THURSDAY-FRIDAY PERIOD...WILL ELECT TO ADD AN INITIAL MENTION OF THE LAKE EFFECT POTENTIAL TO THE HWO. LATER ON IN THE PERIOD...BOTH THE GFS AND ECMWF INDICATE THAT A DECENT CLIPPER-TYPE SYSTEM WILL ROUND THE BASE OF THE MEAN TROUGH AND WORK INTO OUR REGION SOMETIME BETWEEN FRIDAY NIGHT AND SATURDAY...THEN EXIT TO OUR EAST ON SUNDAY WITH A REINFORCING SHOT OF COLDER AND DRIER AIR FOLLOWING ITS PASSAGE. IN TERMS OF PRECIPITATION CHANCES...THIS FEATURE WILL BRING A MORE GENERAL CHANCE OF SNOW SHOWERS BACK INTO THE AREA FOR THE WEEKEND...WHILE ALSO INFLUENCING THE EVOLUTION OF THE LOW-LEVEL WIND FIELD...WHICH IN TURN WILL IMPACT THE ULTIMATE POSITION AND STRENGTH OF ANY LAKE SNOWS. GIVEN THE DISTANT DAY 6-7 TIME FRAME AND THE TYPICAL FORECAST UNCERTAINTY IN BOTH THE TIMING/TRACK/STRENGTH OF THIS FEATURE AND ITS EXACT INFLUENCE ON THE LOW LEVEL WIND FIELDS...FOR NOW HAVE JUST TRENDED POPS BACK TO THE BROADBRUSH LOW-MID CHANCE RANGE FOR NEXT WEEKEND. && .AVIATION /07Z MONDAY THROUGH FRIDAY/... CONDITIONS WILL BEGIN TO DETERIORATE THIS MORNING EARLY MONDAY AS A WARM FRONT OVERSPREADING OUR SUB-FREEZING AREA WILL BRING A PERIOD OF MIXED WINTRY OF PRECIPITATION...INCLUDING THE POTENTIAL OF SLEET AND FREEZING RAIN. AT 07Z KERI REPORTING FZRA AND BUFFALO RADAR ALREADY SHOWING SLEET AND SNOW PUSHING NORTH INTO THE SOUTHERN TIER. THE PRIME THREAT TIME FOR THIS WINTRY MIX AT KJHW/KBUF/KIAG WILL BE FROM 06Z-12Z AND FOR KROC FROM 10Z-18Z PLUS/MINUS. BEYOND THESE TIME FRAMES...THE AIR MASS WILL BECOME WARM ENOUGH DOWN TO THE SURFACE FOR A CHANGE OVER TO ALL RAIN. EXPECT THE LIQUID PRECIP TO TAPER OFF DURING THE LATE AFTERNOON 18Z-20Z AND TRANSITION TO DRIZZLE AND LIGHT FOG...LOWERING TO IFR CONDITIONS THROUGH THE END OF THE TAF PERIOD. OUTLOOK... MONDAY NIGHT...MVFR/IFR WITH MIXED PRECIPITATION LIKELY KART. RAIN/DRIZZLE LIKELY ELSEWHERE. TUESDAY...MVFR WITH RAIN SHOWERS LIKELY. WEDNESDAY...MVFR/IFR WITH RAIN OR SNOW SHOWERS LIKELY. THURSDAY AND FRIDAY...MVFR/LOCALIZED IFR IN LAKE EFFECT SNOW SHOWERS. && .MARINE... A WARM FRONT IS LIFTING NORTH TOWARD THE LAKES EARLY THIS MORNING. THIS WILL BRING A WINTRY MIX OF PRECIPITATION BY MONDAY DAYLIGHT. SOUTHERLY WINDS WILL BUILD WAVES ALONG THE NORTHERN LAKE SHORES TODAY THROUGH WEDNESDAY BUT EXPECT THESE TO GENERALLY REMAIN BELOW SMALL CRAFT CRITERIA. && .HYDROLOGY... WITH THE UPCOMING STRONG WARMUP...NORMALLY ONE WOULD EXPECT THE POTENTIAL FOR SOME ICE JAMS ON AREA CREEKS GIVEN THE TIME OF YEAR. THIS SAID...THIS WINTER HAS BEEN RELATIVELY MILD MUCH OF THE TIME... WITH THE BULK OF ANY ICE FORMATION ON CREEKS LIKELY COMING DURING OUR STRONG COLD SPELL OF THE PAST WEEK...WITH ANY ICE PROBABLY NOT YET REACHING THICKNESSES THAT WOULD POSE A SIGNIFICANT ICE JAM THREAT. THUS...WHILE THESE CANNOT BE AT ALL RULED OUT...AT THIS POINT WE DO NOT ANTICIPATE A STRONG THREAT OF ICE JAMS AND RESULTANT FLOODING ISSUES DURING THE UPCOMING WARMUP. WITH ICE JAMS LIKELY NOT A HUGE CONCERN...AT THIS POINT ANY HYDRO ISSUES THIS WEEK WILL PROBABLY HAVE TO INSTEAD BE DRIVEN BY A COMBINATION OF SNOWMELT AND RAINFALL. WITH OVERALL RAINFALL AMOUNTS LOOKING TO BE RELATIVELY LIGHT THROUGH TUESDAY... /GENERALLY ON THE ORDER OF A TENTH OR TWO TENTHS OF AN INCH PER EVERY 12 HOURS/...FEEL THAT ANY HYDRO CONCERNS SHOULD BE RELATIVELY MINIMAL THROUGH THAT TIME. AFTER THAT...THERE WILL BE THE POTENTIAL FOR SOMEWHAT HEAVIER SHOWERS ALONG AND IN ADVANCE OF A COLD FRONT TUESDAY AND WEDNESDAY...WHICH COULD LEAD TO A SOMEWHAT HIGHER POTENTIAL FOR LOCALIZED HYDRO ISSUES DURING THAT TIME FRAME. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST THIS EVENING FOR NYZ005>008. WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR NYZ003-004-013-014. WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NYZ001-002-010>012-019>021-085. MARINE...NONE. && $$ SYNOPSIS...TMA NEAR TERM...SMITH/WCH SHORT TERM...JJR LONG TERM...JJR AVIATION...SMITH/WCH MARINE...SMITH/WCH HYDROLOGY...JJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1220 PM EST MON JAN 28 2013 .SYNOPSIS... HIGH PRESSURE POSITIONED OFFSHORE WILL CAUSE WARM SOUTHWESTERLY FLOW ACROSS THE CAROLINAS THROUGH WEDNESDAY. A STRONG COLD FRONT WILL CROSS THE AREA WEDNESDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... AS OF 930 AM MONDAY... MAIN FORECAST CHALLENGE TODAY IS MAX TEMPS. NEAR TERM MODEL GUIDANCE SUGGEST MAX TEMPS A GOOD 4-5 DEGREES WARMER THAN CURRENT FORECAST...ESPECIALLY ACROSS THE NORTHERN PIEDMONT INTO THE NORTHERN COASTAL PLAIN. 12Z GSO SOUNDING INDICATE AS THICK LAYER OF WARM AIR JUST 500-1000FT OFF THE SURFACE. GFS BUFKIT SOUNDINGS SUGGEST THIS WARMER AIR REACHING THE SURFACE BY EARLY AFTERNOON. THE RAP AND NAM BUFKIT SOUNDINGS ARE SLOWER (NOT UNTIL 4-5 PM) BUT ALSO SUGGEST WARMER TEMPS AT THE SURFACE. HOWEVER...HAVING A DIFFICULT TIME IDENTIFYING A MECHANISM TO DRAW THIS WARM AIR TO THE SURFACE. NOT COUNTING ON ANY HEATING AS EXPECT OVERCAST SKIES ALL DAY WITH CEILINGS ACTUALLY LOWERING LATER TODAY WITH PATCHES OF DRIZZLE/VERY LIGHT RAIN DEVELOPING AS SLY FLOW ALOFT STRENGTHENS. FOR NOW...HAVE ADJUSTED MAX TEMPS UP 2-3 DEGREES MOST LOCATIONS EXCLUDING THE NW PIEDMONT/TRIAD WHERE RESIDUAL PIEDMONT AIR MASSES HAVE A TENDENCY TO HANG ON. STILL APPEARS A LIKELIHOOD WE WILL SEE PATCHES OF DRIZZLE/LIGHT RAIN DEVELOP THIS AFTERNOON...STARTING FIRST IN THE SOUTHERN PIEDMONT THEN SPREAD NWD. MAY ALSO SEE FOG DEVELOP TOWARD SUNSET WHICH MAY BE LOCALLY DENSE. TONIGHT....WIDESPREAD FOG AND LOW CLOUDS ANTICIPATED WITH POSSIBILITY OF DENSE FOG A REAL CONCERN. TEMPS WILL LIKELY HOLD STEADY IN THE 40S. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 230 AM MONDAY... TUESDAY: ON TUESDAY THE SURFACE HIGH CONTINUES TO MOVE SOUTHEASTWARD OFF THE SOUTH CAROLINA COAST. WITH A LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT APPROACHING FROM THE WEST...CENTRAL NORTH CAROLINA WILL BE IN THE MIDDLE OF A WARM AIR ADVECTION REGIME WHICH WILL INCREASE IN STRENGTH AS THE DAY GOES ON. EXPECT TEMPERATURES DRAMATICALLY HIGHER ON TUESDAY WITH MID 60S NORTHWEST TO NEAR 70 IN THE SOUTHEAST. EXPECT SOME THINNING OF CLOUDS IN THE AFTERNOON BUT OVERALL SHOULD REMAIN PARTLY TO MOSTLY CLOUDY IF NOT OVERCAST. DESPITE THE CLOUDS CENTRAL NC SHOULD REMAIN DRY ON TUESDAY.-ELLIS TUE NIGHT THROUGH WED NIGHT: A PROGRESSIVE PATTERN ALOFT WILL BE IN TRANSITION DURING THE MIDDLE OF THE WEEK AS A HIGHLY AMPLIFIED TROUGH ALOFT COMPRISED OF S/W ENERGY MIGRATES FROM THE FRONT RANGE OF THE ROCKIES TO THE EAST COAST. THIS TROUGH WILL DRIVE A STRONG FRONTAL ZONE...ONE FED BY STRONG MOISTURE TRANSPORT OFF THE GOM -- CHARACTERIZED BY PRECIPITABLE WATER VALUES AROUND 1.5 INCHES OR 2-3 SIGMAS ABOVE AVERAGE -- THROUGH CENTRAL NC WED EVENING. WARM AND BREEZY SOUTHWESTERLY FLOW IN ADVANCE OF THE FRONT WILL SEND TEMPERATURES INTO THE UPPER 60S WEST TO MIDDLE 70S EAST. WIDESPREAD SOAKING SHOWERS WILL ACCOMPANY THE FRONTAL ZONE...WITH PRECIPITATION AMOUNTS EXPECTED TO RANGE BETWEEN A HALF INCH AND ONE INCH...HIGHEST OVER THE WESTERN PIEDMONT...WHERE FORCING FOR ASCENT WILL BE MAXIMIZED BY THE LIFTING SOUTHERN PORTION OF THE TROUGH ALOFT. WHILE DEEP AND LOW LEVEL SHEAR WILL BE QUITE STRONG...WEAK LAPSE RATES ALOFT SUGGEST INSTABILITY WILL BE WEAK TO ABSENT...SO FORCING FOR ASCENT WILL NEED TO BE SUFFICIENTLY STRONG AND CONCENTRATED TO SUPPORT A STRONGLY FORCED/SHALLOW CONVECTIVE LINE ALONG THE FRONT. EVEN IF THAT WERE TO OCCUR...THE CONVECTIVE LINE WOULD BE DEVOID OF LIGHTNING...SO THUNDER WILL BE KEPT OUT OF THE FORECAST. HOWEVER...MOMENTUM TRANSPORT FROM BOWING LINE SEGMENTS WOULD BE CAPABLE OF PRODUCING 40-60 KT WIND GUSTS. ANY TORNADIC POTENTIAL WILL BE LOW..DESPITE FAVORABLE SHEAR PROFILES...OWING TO EH LACK OF INSTABILITY. HAVE SLOWED THE ARRIVAL AND DEPARTURE OF THE SHOWERS BY ABOUT SIX HOURS IN THE GRIDDED/TEXT FORECAST...CENTERED DURING THE EVENING HOURS. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 335 AM MONDAY... STRONG CAA BEHIND THE FRONT WILL RESULT IN TEMPERATURES THU ABOUT 20 DEGREES COOLER THAN THOSE OF WED. ANOTHER ARCTIC HIGH WILL HEAD TOWARD OUR REGION FRI-SAT...LED SOUTHEASTWARD BY A CLIPPER-TYPE WAVE AND ACCOMPANYING SURFACE COLD FRONT ON FRI. MODEL CROSS SECTIONS INDICATE SUFFICIENT LIFT AND SATURATION TO GENERATE SNOW FROM THE NORTHERN NC PIEDMONT NORTHWARD THROUGH VA...BUT A DEEP AND DRY SUB-CLOUD LAYER SHOULD RESULT IN ONLY VIRGA OR A FEW FLURRIES/SPRINKLES NORTH OF HIGHWAY 64 FRI MORNING THROUGH EARLY AFTERNOON...SLIGHTLY LATER THAN EARLIER PROJECTIONS. OPPOSED BY STRONG CAA AND A BRISK NORTHWESTERLY WIND ON FRI...TEMPERATURES WILL STRUGGLE TO REACH 40 DEGREES ACROSS THE NORTHERN PIEDMONT...TO UPPER 40S TOWARD THE SC LINE. THE CENTER OF THE HIGH WILL DRIFT OVERHEAD BY SAT MORNING...WHICH SUGGESTS EXCELLENT RADIATIONAL COOLING WILL BE LIKELY...HINDERED ONLY BY CIRRUS ASSOCIATED WITH ANOTHER DISTURBANCE IN NW FLOW ALOFT. PROJECTED LOW LEVEL THICKNESS VALUES AROUND 1370 METERS SAT MORNING SUGGEST LOWS IN THE UPPER TEENS TO LOWER 20S...WITH HIGHS IN THE LOWER TO MIDDLE 40S ON SAT. ANOTHER CLIPPER-TYPE LOW WILL CROSS THE MIDDLE ATLANTIC SAT NIGHT...BEFORE DEEPENING OFF THE NEW ENGLAND COAST ON SUN. ASSOCIATED PRECIPITATION IS ACCORDINGLY EXPECTED TO OCCUR UPWIND OF THE NC BLUE RIDGE...AND NORTH OF THE VA STATE LINE. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 1220 PM MONDAY... WIDESPREAD MVFR CEILINGS WILL PERSIST THIS AFTERNOON THEN LOWER INTO THE IFR/LIFR RANGE THIS EVENING AS SLY FLOW BRINGS GULF MOISTURE INTO THE REGION. THESE LOW CEILINGS ALONG WITH AREAS OF MVFR/IFR FOG AND DRIZZLE WILL CREATE ADVERSE AVIATION WEATHER CONDITIONS ACROSS CENTRAL NC THROUGH THE NIGHT INTO TUESDAY MORNING. THE LOW CLOUDS WILL GRADUALLY LIFT AND DISSIPATE TUESDAY MORNING...LEADING TO VFR CONDITIONS AND SCATTERED CLOUD BASES BETWEEN 3000-4000 FT IN THE AFTERNOON. A FEW RAIN SHOWERS MAY SKIRT THE TRIAD TERMINALS LATE IN THE DAY. TUESDAY NIGHT...ANOTHER ROUND OF LOW CLOUDS ANTICIPATED WITH CEILINGS AGAIN THE IFR/LIFR CATEGORIES. ANY RAIN SHOWERS THAT OCCUR WILL BE CONFINED TO AREAS NEAR THE TRIAD TERMINALS AND BE ISOLATED. WINDY CONDITIONS EXPECTED WEDNESDAY AHEAD OF A STRONG COLD FRONT THAT WILL CROSS THE AREA WEDNESDAY NIGHT. AHEAD OF THIS FRONT...EXPECT WIDESPREAD SHOWERS AND ISOLATED T-STORMS TO OCCUR...MAINLY LATE WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING. WIND GUSTS 30-40 MPH MAY OCCUR AHEAD OF THE FRONT. SHARPLY COLDER TEMPERATURES EXPECTED THURSDAY INTO SATURDAY WITH VFR CONDITIONS EXPECTED. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...SEC NEAR TERM...WSS SHORT TERM...ELLIS/MWS LONG TERM...MWS AVIATION...WSS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
930 AM EST MON JAN 28 2013 .SYNOPSIS... WARM AND MOIST SOUTHWESTERLY FLOW WILL RIDE ATOP A LINGERING RIDGE OF COOL SURFACE HIGH PRESSURE OVER THE CAROLINAS THROUGH TONIGHT. THE WARM SOUTHWESTERLY FLOW WILL REACH THE SURFACE BY TUESDAY AFTERNOON...AND CONTINUE THROUGH WEDNESDAY...IN ADVANCE OF A STRONG COLD FRONT THAT WILL CROSS THE MIDDLE ATLANTIC AND CAROLINAS WEDNESDAY EVENING. && .NEAR TERM /THROUGH TONIGHT/... AS OF 930 AM MONDAY... MONDAY AND MONDAY NIGHT: MID MORNING TEMPS HAVE WARMED INTO THE MID AND UPPER 30S ACROSS CENTRAL NC. THUS...FZRA THREAT ACROSS THE FAR NORTH HAS ENDED AND THE ADVISORY ALLOWED TO EXPIRE. NEXT FORECAST CHALLENGE IS MAX TEMPS FOR TODAY. NEAR TERM MODEL GUIDANCE SUGGEST MAX TEMPS A GOOD 4-5 DEGREES WARMER THAN CURRENT FORECAST...ESPECIALLY ACROSS THE NORTHERN PIEDMONT INTO THE NORTHERN COASTAL PLAIN. 12Z GSO SOUNDING INDICATE AS THICK LAYER OF WARM AIR JUST 500-1000FT OFF THE SURFACE. GFS BUFKIT SOUNDINGS SUGGEST THIS WARMER AIR REACHING THE SURFACE BY EARLY AFTERNOON. THE RAP AND NAM BUFKIT SOUNDINGS ARE SLOWER (NOT UNTIL 4-5 PM) BUT ALSO SUGGEST WARMER TEMPS AT THE SURFACE. HOWEVER...HAVING A DIFFICULT TIME IDENTIFYING A MECHANISM TO DRAW THIS WARM AIR TO THE SURFACE. NOT COUNTING ON ANY HEATING AS EXPECT OVERCAST SKIES ALL DAY WITH CEILINGS ACTUALLY LOWERING LATER TODAY WITH PATCHES OF DRIZZLE/VERY LIGHT RAIN DEVELOPING AS SLY FLOW ALOFT STRENGTHENS. FOR NOW...HAVE ADJUSTED MAX TEMPS UP 2-3 DEGREES MOST LOCATIONS EXCLUDING THE NW PIEDMONT/TRIAD WHERE RESIDUAL PIEDMONT AIR MASSES HAVE A TENDENCY TO HANG ON. STILL APPEARS A LIKELIHOOD WE WILL SEE PATCHES OF DRIZZLE/LIGHT RAIN DEVELOP THIS AFTERNOON...STARTING FIRST IN THE SOUTHERN PIEDMONT THEN SPREAD NWD. MAY ALSO SEE FOG DEVELOP TOWARD SUNSET WHICH MAY BE LOCALLY DENSE. TONIGHT....WIDESPREAD FOG AND LOW CLOUDS ANTICIPATED WITH POSSIBILITY OF DENSE FOG A REAL CONCERN. TEMPS WILL LIKELY HOLD STEADY IN THE 40S. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 230 AM MONDAY... TUESDAY: ON TUESDAY THE SURFACE HIGH CONTINUES TO MOVE SOUTHEASTWARD OFF THE SOUTH CAROLINA COAST. WITH A LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT APPROACHING FROM THE WEST...CENTRAL NORTH CAROLINA WILL BE IN THE MIDDLE OF A WARM AIR ADVECTION REGIME WHICH WILL INCREASE IN STRENGTH AS THE DAY GOES ON. EXPECT TEMPERATURES DRAMATICALLY HIGHER ON TUESDAY WITH MID 60S NORTHWEST TO NEAR 70 IN THE SOUTHEAST. EXPECT SOME THINNING OF CLOUDS IN THE AFTERNOON BUT OVERALL SHOULD REMAIN PARTLY TO MOSTLY CLOUDY IF NOT OVERCAST. DESPITE THE CLOUDS CENTRAL NC SHOULD REMAIN DRY ON TUESDAY.-ELLIS TUE NIGHT THROUGH WED NIGHT: A PROGRESSIVE PATTERN ALOFT WILL BE IN TRANSITION DURING THE MIDDLE OF THE WEEK AS A HIGHLY AMPLIFIED TROUGH ALOFT COMPRISED OF S/W ENERGY MIGRATES FROM THE FRONT RANGE OF THE ROCKIES TO THE EAST COAST. THIS TROUGH WILL DRIVE A STRONG FRONTAL ZONE...ONE FED BY STRONG MOISTURE TRANSPORT OFF THE GOM -- CHARACTERIZED BY PRECIPITABLE WATER VALUES AROUND 1.5 INCHES OR 2-3 SIGMAS ABOVE AVERAGE -- THROUGH CENTRAL NC WED EVENING. WARM AND BREEZY SOUTHWESTERLY FLOW IN ADVANCE OF THE FRONT WILL SEND TEMPERATURES INTO THE UPPER 60S WEST TO MIDDLE 70S EAST. WIDESPREAD SOAKING SHOWERS WILL ACCOMPANY THE FRONTAL ZONE...WITH PRECIPITATION AMOUNTS EXPECTED TO RANGE BETWEEN A HALF INCH AND ONE INCH...HIGHEST OVER THE WESTERN PIEDMONT...WHERE FORCING FOR ASCENT WILL BE MAXIMIZED BY THE LIFTING SOUTHERN PORTION OF THE TROUGH ALOFT. WHILE DEEP AND LOW LEVEL SHEAR WILL BE QUITE STRONG...WEAK LAPSE RATES ALOFT SUGGEST INSTABILITY WILL BE WEAK TO ABSENT...SO FORCING FOR ASCENT WILL NEED TO BE SUFFICIENTLY STRONG AND CONCENTRATED TO SUPPORT A STRONGLY FORCED/SHALLOW CONVECTIVE LINE ALONG THE FRONT. EVEN IF THAT WERE TO OCCUR...THE CONVECTIVE LINE WOULD BE DEVOID OF LIGHTNING...SO THUNDER WILL BE KEPT OUT OF THE FORECAST. HOWEVER...MOMENTUM TRANSPORT FROM BOWING LINE SEGMENTS WOULD BE CAPABLE OF PRODUCING 40-60 KT WIND GUSTS. ANY TORNADIC POTENTIAL WILL BE LOW..DESPITE FAVORABLE SHEAR PROFILES...OWING TO EH LACK OF INSTABILITY. HAVE SLOWED THE ARRIVAL AND DEPARTURE OF THE SHOWERS BY ABOUT SIX HOURS IN THE GRIDDED/TEXT FORECAST...CENTERED DURING THE EVENING HOURS. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 335 AM MONDAY... STRONG CAA BEHIND THE FRONT WILL RESULT IN TEMPERATURES THU ABOUT 20 DEGREES COOLER THAN THOSE OF WED. ANOTHER ARCTIC HIGH WILL HEAD TOWARD OUR REGION FRI-SAT...LED SOUTHEASTWARD BY A CLIPPER-TYPE WAVE AND ACCOMPANYING SURFACE COLD FRONT ON FRI. MODEL CROSS SECTIONS INDICATE SUFFICIENT LIFT AND SATURATION TO GENERATE SNOW FROM THE NORTHERN NC PIEDMONT NORTHWARD THROUGH VA...BUT A DEEP AND DRY SUB-CLOUD LAYER SHOULD RESULT IN ONLY VIRGA OR A FEW FLURRIES/SPRINKLES NORTH OF HIGHWAY 64 FRI MORNING THROUGH EARLY AFTERNOON...SLIGHTLY LATER THAN EARLIER PROJECTIONS. OPPOSED BY STRONG CAA AND A BRISK NORTHWESTERLY WIND ON FRI...TEMPERATURES WILL STRUGGLE TO REACH 40 DEGREES ACROSS THE NORTHERN PIEDMONT...TO UPPER 40S TOWARD THE SC LINE. THE CENTER OF THE HIGH WILL DRIFT OVERHEAD BY SAT MORNING...WHICH SUGGESTS EXCELLENT RADIATIONAL COOLING WILL BE LIKELY...HINDERED ONLY BY CIRRUS ASSOCIATED WITH ANOTHER DISTURBANCE IN NW FLOW ALOFT. PROJECTED LOW LEVEL THICKNESS VALUES AROUND 1370 METERS SAT MORNING SUGGEST LOWS IN THE UPPER TEENS TO LOWER 20S...WITH HIGHS IN THE LOWER TO MIDDLE 40S ON SAT. ANOTHER CLIPPER-TYPE LOW WILL CROSS THE MIDDLE ATLANTIC SAT NIGHT...BEFORE DEEPENING OFF THE NEW ENGLAND COAST ON SUN. ASSOCIATED PRECIPITATION IS ACCORDINGLY EXPECTED TO OCCUR UPWIND OF THE NC BLUE RIDGE...AND NORTH OF THE VA STATE LINE. && .AVIATION /13Z MONDAY THROUGH FRIDAY/... AS OF 630 AM MONDAY... 24 HOUR TAF PERIOD: PATCHY LIGHT RAIN OR DRIZZLE WILL CONTINUE AT MOST LOCATIONS THIS MORNING WITH KINT AND KGSO ENDING WITHIN THE HOUR. KFAY COULD SEE SOME LIGHT DRIZZLE BUT KRDU AND KRWI WILL SEE THE MOST PRECIPITATION THIS MORNING. WITH TEMPERATURES RIGHT AROUND FREEZING...FREEZING RAIN IS STILL NOT OUT OF THE QUESTION...MOST LIKELY AT KRWI. OTHERWISE LIGHT SOUTHERLY TO SOUTHWESTERLY FLOW WILL TAKE OVER TODAY. SOME MVFR/IFR CEILINGS OUT THERE THIS MORNING SHOULD LIFT TO VFR EARLY THIS AFTERNOON...HOWEVER CLOUD COVER WILL CONTINUE THIS AFTERNOON WITH CEILINGS AGAIN DETERIORATING LATE THIS AFTERNOON INTO THE EVENING. WHILE CONDITIONS ARE FAVORABLE FOR WIDESPREAD FOG OVERNIGHT MONDAY INTO TUESDAY...SOME HIGHER WIND SPEEDS COULD CREATE MORE OF A LOW STRATUS SITUATION WITH LIFR CEILINGS EXPECTED EVERYWHERE. VISIBILITIES MAY COME DOWN VARYING AMOUNTS BUT THAT WONT MATTER GIVEN CIGS ARE EXPECTED TO FALL TO LIFR. LOOKING AHEAD: FOG AND OR LOW STRATUS WILL BE LIKELY TUESDAY MORNING. ADVERSE CONDITIONS ARE ALSO LIKELY WEDNESDAY INTO THURSDAY WITH THE PASSAGE OF A FRONTAL SYSTEM. ON FRIDAY...NORTHERN SITES MAY HAVE A CHANCE FOR SOME LIGHT SNOW SHOWERS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...MWS NEAR TERM...WSS SHORT TERM...ELLIS/MWS LONG TERM...MWS AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
727 AM EST MON JAN 28 2013 .SYNOPSIS... WARM AND MOIST SOUTHWESTERLY FLOW WILL RIDE ATOP A LINGERING RIDGE OF COOL SURFACE HIGH PRESSURE OVER THE CAROLINAS THROUGH TONIGHT. THE WARM SOUTHWESTERLY FLOW WILL REACH THE SURFACE BY TUESDAY AFTERNOON...AND CONTINUE THROUGH WEDNESDAY...IN ADVANCE OF A STRONG COLD FRONT THAT WILL CROSS THE MIDDLE ATLANTIC AND CAROLINAS WEDNESDAY EVENING. && .NEAR TERM /THROUGH TONIGHT/... AS OF 230 AM MONDAY... MONDAY AND MONDAY NIGHT: FREEZING RAIN ADVISORY EXTENDED TO INCLUDE COUNTIES IN THE NORTHEASTERN PIEDMONT OF NC THROUGH 9AM... HAVE EXTENDED THE FREEZING RAIN ADVISORY THROUGH THE NORTHEASTERN COUNTIES BASED ON THE FACT THAT BOTH CURRENT TEMPERATURES AND WET BULB TEMPERATURES REMAIN BELOW FREEZING IN THIS AREA...ALONG THE AXIS OF THE DRY AIR SURFACE RIDGE...AND SINCE CURRENT RADAR TRENDS AND CURRENT RUNS OF THE RAP/RUC MODEL SHOW THE AREA OF PRECIPITATION EXPANDING FROM THE COASTAL PLAIN TO THE WEST OF THE TRIAD WILL CONTINUE EASTWARD ACROSS THE CWA IMPACTING THE NORTHEASTERN COUNTIES THROUGH 9 AM. CURRENT SURFACE ANALYSIS SHOWS SURFACE HIGH PRESSURE SET UP OVER THE TIDEWATER VIRGINIA REGION. THIS HIGH IS RESPONSIBLE FOR SUBFREEZING TEMPERATURES IN EASTERN NORTH CAROLINA WITH NORTHEASTERLY FLOW. FURTHER WEST HOWEVER...RETURN FLOW AROUND THE HIGH HAS KEPT TEMPERATURES MAINLY IN THE MIDDLE 30S. CURRENT RADAR TRENDS SHOW REFLECTIVITIES SPLITTING WITH ONE AREA MOVING SWIFTLY ACROSS THE NORTHERN TIER OF THE CWA WITH ANOTHER BAND TO THE SOUTH. THE OCCURRENCE OF FREEZING RAIN IS VERY QUESTIONABLE AT THIS POINT DUE TO A COUPLE OF FACTORS. CLOUD COVER AND SOUTHERLY FLOW IN THE WEST HAVE KEPT TEMPERATURES UP. WHILE SOME LIGHT RAIN OR DRIZZLE MAY BE LIKELY...FREEZING RAIN IS NOT AS LIKELY UNLESS ENOUGH WETBULBING OCCURS TO BRING TEMPERATURES BACK DOWN TO FREEZING. FURTHER TO THE EAST...TEMPERATURES HAVE ALREADY ACHIEVED THE FREEZING MARK BUT AS THE HIGH SLIDES EASTWARD ALONG WITH IT WILL COME THE CLOUDS AND SOUTHERLY FLOW AND A RISE IN THE SURFACE TEMPERATURES. AT THIS POINT THE MOST LIKELY AREA FOR FREEZING RAIN WILL BE THE NORTHEAST BECAUSE EVEN IF TEMPERATURES RISE BACK ABOVE FREEZING...ONCE PRECIPITATION STARTS WETBULBING SHOULD BRING IT BACK DOWN. WITH A NORTH TO SOUTH ORIENTED BAND MOVING ACROSS THE NORTH...ANY PRECIPITATION THAT DOES OCCUR SHOULD ONLY LAST AN HOUR OR TWO MAXIMUM. IT IS LIKELY THAT THE FREEZING RAIN ADVISORY WILL HAVE TO BE TRIMMED BACK FROM WEST TO EAST OR PERHAPS CANCELLED ALL TOGETHER AS CONDITIONS WARRANT. CURRENT RAP SOUNDINGS INDICATE THAT MANY SITES WILL REMAIN ABOVE FREEZING WITH THE EXCEPTION OF THOSE IN THE FAR EASTERN PORTIONS OF THE AREA. WHETHER OR NOT PRECIPITATION ARRIVES IN TIME TO TAKE ADVANTAGE OF THOSE LOWER TEMPERATURES REMAINS TO BE SEEN. REGARDLESS...EXPECT PATCHY SPRINKLES OR LIGHT RAIN THROUGH SUNRISE WITH ISOLATED PATCHES OF FREEZING RAIN MOST LIKELY IN THE NORTHEAST. MINIMUM TEMPERATURES HAVE ALREADY BOTTOMED OUT IN MOST CASES MID TO UPPER 20S EAST AND LOWER 30S WEST. ANY ONGOING PRECIPITATION SHOULD TAPER OFF MONDAY MORNING WITH A SOME FOG POSSIBLE IN LOCALIZED AREAS. SKIES WILL REMAIN OVERCAST FOR MOST OF THE DAY ON MONDAY. COMBINING THIS ALONG WITH AFTERNOON THICKNESS VALUES IN THE MID 1300S SHOULD KEEP MAXIMUM TEMPERATURES DOWN ON MONDAY...MID 40S NORTHWEST TO UPPER 40S TO LOWER 50S IN THE SOUTHEAST. SOME LIGHT RAIN OR DRIZZLE IS POSSIBLE THROUGHOUT MUCH OF THE DAY ON MONDAY. CEILINGS WILL GRADUALLY COME DOWN MOST LIKELY TO IFR/LIFR LATER MONDAY NIGHT INTO TUESDAY MORNING. WITH BOTH TEMPERATURES AND DEWPOINTS IN THE MID 40S TUESDAY NIGHT...CONDITIONS ARE FAVORABLE FOR A WIDESPREAD FOG EVENT. FORECAST SOUNDINGS ARE HINTING AT THIS PROBABILITY AND WILL CONTINUE TO MONITOR THE SITUATION FOR A POSSIBLE DENSE FOG ADVISORY MONDAY NIGHT INTO TUESDAY MORNING. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 230 AM MONDAY... TUESDAY: ON TUESDAY THE SURFACE HIGH CONTINUES TO MOVE SOUTHEASTWARD OFF THE SOUTH CAROLINA COAST. WITH A LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT APPROACHING FROM THE WEST...CENTRAL NORTH CAROLINA WILL BE IN THE MIDDLE OF A WARM AIR ADVECTION REGIME WHICH WILL INCREASE IN STRENGTH AS THE DAY GOES ON. EXPECT TEMPERATURES DRAMATICALLY HIGHER ON TUESDAY WITH MID 60S NORTHWEST TO NEAR 70 IN THE SOUTHEAST. EXPECT SOME THINNING OF CLOUDS IN THE AFTERNOON BUT OVERALL SHOULD REMAIN PARTLY TO MOSTLY CLOUDY IF NOT OVERCAST. DESPITE THE CLOUDS CENTRAL NC SHOULD REMAIN DRY ON TUESDAY.-ELLIS TUE NIGHT THROUGH WED NIGHT: A PROGRESSIVE PATTERN ALOFT WILL BE IN TRANSITION DURING THE MIDDLE OF THE WEEK AS A HIGHLY AMPLIFIED TROUGH ALOFT COMPRISED OF S/W ENERGY MIGRATES FROM THE FRONT RANGE OF THE ROCKIES TO THE EAST COAST. THIS TROUGH WILL DRIVE A STRONG FRONTAL ZONE...ONE FED BY STRONG MOISTURE TRANSPORT OFF THE GOM -- CHARACTERIZED BY PRECIPITABLE WATER VALUES AROUND 1.5 INCHES OR 2-3 SIGMAS ABOVE AVERAGE -- THROUGH CENTRAL NC WED EVENING. WARM AND BREEZY SOUTHWESTERLY FLOW IN ADVANCE OF THE FRONT WILL SEND TEMPERATURES INTO THE UPPER 60S WEST TO MIDDLE 70S EAST. WIDESPREAD SOAKING SHOWERS WILL ACCOMPANY THE FRONTAL ZONE...WITH PRECIPITATION AMOUNTS EXPECTED TO RANGE BETWEEN A HALF INCH AND ONE INCH...HIGHEST OVER THE WESTERN PIEDMONT...WHERE FORCING FOR ASCENT WILL BE MAXIMIZED BY THE LIFTING SOUTHERN PORTION OF THE TROUGH ALOFT. WHILE DEEP AND LOW LEVEL SHEAR WILL BE QUITE STRONG...WEAK LAPSE RATES ALOFT SUGGEST INSTABILITY WILL BE WEAK TO ABSENT...SO FORCING FOR ASCENT WILL NEED TO BE SUFFICIENTLY STRONG AND CONCENTRATED TO SUPPORT A STRONGLY FORCED/SHALLOW CONVECTIVE LINE ALONG THE FRONT. EVEN IF THAT WERE TO OCCUR...THE CONVECTIVE LINE WOULD BE DEVOID OF LIGHTNING...SO THUNDER WILL BE KEPT OUT OF THE FORECAST. HOWEVER...MOMENTUM TRANSPORT FROM BOWING LINE SEGMENTS WOULD BE CAPABLE OF PRODUCING 40-60 KT WIND GUSTS. ANY TORNADIC POTENTIAL WILL BE LOW..DESPITE FAVORABLE SHEAR PROFILES...OWING TO EH LACK OF INSTABILITY. HAVE SLOWED THE ARRIVAL AND DEPARTURE OF THE SHOWERS BY ABOUT SIX HOURS IN THE GRIDDED/TEXT FORECAST...CENTERED DURING THE EVENING HOURS. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 335 AM MONDAY... STRONG CAA BEHIND THE FRONT WILL RESULT IN TEMPERATURES THU ABOUT 20 DEGREES COOLER THAN THOSE OF WED. ANOTHER ARCTIC HIGH WILL HEAD TOWARD OUR REGION FRI-SAT...LED SOUTHEASTWARD BY A CLIPPER-TYPE WAVE AND ACCOMPANYING SURFACE COLD FRONT ON FRI. MODEL CROSS SECTIONS INDICATE SUFFICIENT LIFT AND SATURATION TO GENERATE SNOW FROM THE NORTHERN NC PIEDMONT NORTHWARD THROUGH VA...BUT A DEEP AND DRY SUB-CLOUD LAYER SHOULD RESULT IN ONLY VIRGA OR A FEW FLURRIES/SPRINKLES NORTH OF HIGHWAY 64 FRI MORNING THROUGH EARLY AFTERNOON...SLIGHTLY LATER THAN EARLIER PROJECTIONS. OPPOSED BY STRONG CAA AND A BRISK NORTHWESTERLY WIND ON FRI...TEMPERATURES WILL STRUGGLE TO REACH 40 DEGREES ACROSS THE NORTHERN PIEDMONT...TO UPPER 40S TOWARD THE SC LINE. THE CENTER OF THE HIGH WILL DRIFT OVERHEAD BY SAT MORNING...WHICH SUGGESTS EXCELLENT RADIATIONAL COOLING WILL BE LIKELY...HINDERED ONLY BY CIRRUS ASSOCIATED WITH ANOTHER DISTURBANCE IN NW FLOW ALOFT. PROJECTED LOW LEVEL THICKNESS VALUES AROUND 1370 METERS SAT MORNING SUGGEST LOWS IN THE UPPER TEENS TO LOWER 20S...WITH HIGHS IN THE LOWER TO MIDDLE 40S ON SAT. ANOTHER CLIPPER-TYPE LOW WILL CROSS THE MIDDLE ATLANTIC SAT NIGHT...BEFORE DEEPENING OFF THE NEW ENGLAND COAST ON SUN. ASSOCIATED PRECIPITATION IS ACCORDINGLY EXPECTED TO OCCUR UPWIND OF THE NC BLUE RIDGE...AND NORTH OF THE VA STATE LINE. && .AVIATION /13Z MONDAY THROUGH FRIDAY/... AS OF 630 AM MONDAY... 24 HOUR TAF PERIOD: PATCHY LIGHT RAIN OR DRIZZLE WILL CONTINUE AT MOST LOCATIONS THIS MORNING WITH KINT AND KGSO ENDING WITHIN THE HOUR. KFAY COULD SEE SOME LIGHT DRIZZLE BUT KRDU AND KRWI WILL SEE THE MOST PRECIPITATION THIS MORNING. WITH TEMPERATURES RIGHT AROUND FREEZING...FREEZING RAIN IS STILL NOT OUT OF THE QUESTION...MOST LIKELY AT KRWI. OTHERWISE LIGHT SOUTHERLY TO SOUTHWESTERLY FLOW WILL TAKE OVER TODAY. SOME MVFR/IFR CEILINGS OUT THERE THIS MORNING SHOULD LIFT TO VFR EARLY THIS AFTERNOON...HOWEVER CLOUD COVER WILL CONTINUE THIS AFTERNOON WITH CEILINGS AGAIN DETERIORATING LATE THIS AFTERNOON INTO THE EVENING. WHILE CONDITIONS ARE FAVORABLE FOR WIDESPREAD FOG OVERNIGHT MONDAY INTO TUESDAY...SOME HIGHER WIND SPEEDS COULD CREATE MORE OF A LOW STRATUS SITUATION WITH LIFR CEILINGS EXPECTED EVERYWHERE. VISIBILITIES MAY COME DOWN VARYING AMOUNTS BUT THAT WONT MATTER GIVEN CIGS ARE EXPECTED TO FALL TO LIFR. LOOKING AHEAD: FOG AND OR LOW STRATUS WILL BE LIKELY TUESDAY MORNING. ADVERSE CONDITIONS ARE ALSO LIKELY WEDNESDAY INTO THURSDAY WITH THE PASSAGE OF A FRONTAL SYSTEM. ON FRIDAY...NORTHERN SITES MAY HAVE A CHANCE FOR SOME LIGHT SNOW SHOWERS. && .RAH WATCHES/WARNINGS/ADVISORIES... FREEZING RAIN ADVISORY UNTIL 9 AM EST THIS MORNING FOR NCZ007>011-024>028-041-043. && $$ SYNOPSIS...MWS NEAR TERM...ELLIS SHORT TERM...ELLIS/MWS LONG TERM...MWS AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
632 AM EST MON JAN 28 2013 .SYNOPSIS... WARM AND MOIST SOUTHWESTERLY FLOW WILL RIDE ATOP A LINGERING RIDGE OF COOL SURFACE HIGH PRESSURE OVER THE CAROLINAS THROUGH TONIGHT. THE WARM SOUTHWESTERLY FLOW WILL REACH THE SURFACE BY TUESDAY AFTERNOON...AND CONTINUE THROUGH WEDNESDAY...IN ADVANCE OF A STRONG COLD FRONT THAT WILL CROSS THE MIDDLE ATLANTIC AND CAROLINAS WEDNESDAY EVENING. && .NEAR TERM /THROUGH TONIGHT/... AS OF 230 AM MONDAY... MONDAY AND MONDAY NIGHT: ...FREEZING RAIN ADVISORY EXTENDED TO INCLUDE COUNTIES IN THE NORTHEASTERN PIEDMONT OF NC THROUGH 9AM... HAVE EXTENDED THE FREEZING RAIN ADVISORY THROUGH THE NORTHEASTERN COUNTIES BASED ON THE FACT THAT BOTH CURRENT TEMPERATURES AND WET BULB TEMPERATURES REMAIN BELOW FREEZING IN THIS AREA...ALONG THE AXIS OF THE DRY AIR SURFACE RIDGE...AND SINCE CURRENT RADAR TRENDS AND CURRENT RUNS OF THE RAP/RUC MODEL SHOW THE AREA OF PRECIPITATION EXPANDING FROM THE COASTAL PLAIN TO THE WEST OF THE TRIAD WILL CONTINUE EASTWARD ACROSS THE CWA IMPACTING THE NORTHEASTERN COUNTIES THROUGH 9 AM. CURRENT SURFACE ANALYSIS SHOWS SURFACE HIGH PRESSURE SET UP OVER THE TIDEWATER VIRGINIA REGION. THIS HIGH IS RESPONSIBLE FOR SUBFREEZING TEMPERATURES IN EASTERN NORTH CAROLINA WITH NORTHEASTERLY FLOW. FURTHER WEST HOWEVER...RETURN FLOW AROUND THE HIGH HAS KEPT TEMPERATURES MAINLY IN THE MIDDLE 30S. CURRENT RADAR TRENDS SHOW REFLECTIVITIES SPLITTING WITH ONE AREA MOVING SWIFTLY ACROSS THE NORTHERN TIER OF THE CWA WITH ANOTHER BAND TO THE SOUTH. THE OCCURRENCE OF FREEZING RAIN IS VERY QUESTIONABLE AT THIS POINT DUE TO A COUPLE OF FACTORS. CLOUD COVER AND SOUTHERLY FLOW IN THE WEST HAVE KEPT TEMPERATURES UP. WHILE SOME LIGHT RAIN OR DRIZZLE MAY BE LIKELY...FREEZING RAIN IS NOT AS LIKELY UNLESS ENOUGH WETBULBING OCCURS TO BRING TEMPERATURES BACK DOWN TO FREEZING. FURTHER TO THE EAST...TEMPERATURES HAVE ALREADY ACHIEVED THE FREEZING MARK BUT AS THE HIGH SLIDES EASTWARD ALONG WITH IT WILL COME THE CLOUDS AND SOUTHERLY FLOW AND A RISE IN THE SURFACE TEMPERATURES. AT THIS POINT THE MOST LIKELY AREA FOR FREEZING RAIN WILL BE THE NORTHEAST BECAUSE EVEN IF TEMPERATURES RISE BACK ABOVE FREEZING...ONCE PRECIPITATION STARTS WETBULBING SHOULD BRING IT BACK DOWN. WITH A NORTH TO SOUTH ORIENTED BAND MOVING ACROSS THE NORTH...ANY PRECIPITATION THAT DOES OCCUR SHOULD ONLY LAST AN HOUR OR TWO MAXIMUM. IT IS LIKELY THAT THE FREEZING RAIN ADVISORY WILL HAVE TO BE TRIMMED BACK FROM WEST TO EAST OR PERHAPS CANCELLED ALL TOGETHER AS CONDITIONS WARRANT. CURRENT RAP SOUNDINGS INDICATE THAT MANY SITES WILL REMAIN ABOVE FREEZING WITH THE EXCEPTION OF THOSE IN THE FAR EASTERN PORTIONS OF THE AREA. WHETHER OR NOT PRECIPITATION ARRIVES IN TIME TO TAKE ADVANTAGE OF THOSE LOWER TEMPERATURES REMAINS TO BE SEEN. REGARDLESS...EXPECT PATCHY SPRINKLES OR LIGHT RAIN THROUGH SUNRISE WITH ISOLATED PATCHES OF FREEZING RAIN MOST LIKELY IN THE NORTHEAST. MINIMUM TEMPERATURES HAVE ALREADY BOTTOMED OUT IN MOST CASES MID TO UPPER 20S EAST AND LOWER 30S WEST. ANY ONGOING PRECIPITATION SHOULD TAPER OFF MONDAY MORNING WITH A SOME FOG POSSIBLE IN LOCALIZED AREAS. SKIES WILL REMAIN OVERCAST FOR MOST OF THE DAY ON MONDAY. COMBINING THIS ALONG WITH AFTERNOON THICKNESS VALUES IN THE MID 1300S SHOULD KEEP MAXIMUM TEMPERATURES DOWN ON MONDAY...MID 40S NORTHWEST TO UPPER 40S TO LOWER 50S IN THE SOUTHEAST. SOME LIGHT RAIN OR DRIZZLE IS POSSIBLE THROUGHOUT MUCH OF THE DAY ON MONDAY. CEILINGS WILL GRADUALLY COME DOWN MOST LIKELY TO IFR/LIFR LATER MONDAY NIGHT INTO TUESDAY MORNING. WITH BOTH TEMPERATURES AND DEWPOINTS IN THE MID 40S TUESDAY NIGHT...CONDITIONS ARE FAVORABLE FOR A WIDESPREAD FOG EVENT. FORECAST SOUNDINGS ARE HINTING AT THIS PROBABILITY AND WILL CONTINUE TO MONITOR THE SITUATION FOR A POSSIBLE DENSE FOG ADVISORY MONDAY NIGHT INTO TUESDAY MORNING. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 230 AM MONDAY... TUESDAY: ON TUESDAY THE SURFACE HIGH CONTINUES TO MOVE SOUTHEASTWARD OFF THE SOUTH CAROLINA COAST. WITH A LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT APPROACHING FROM THE WEST...CENTRAL NORTH CAROLINA WILL BE IN THE MIDDLE OF A WARM AIR ADVECTION REGIME WHICH WILL INCREASE IN STRENGTH AS THE DAY GOES ON. EXPECT TEMPERATURES DRAMATICALLY HIGHER ON TUESDAY WITH MID 60S NORTHWEST TO NEAR 70 IN THE SOUTHEAST. EXPECT SOME THINNING OF CLOUDS IN THE AFTERNOON BUT OVERALL SHOULD REMAIN PARTLY TO MOSTLY CLOUDY IF NOT OVERCAST. DESPITE THE CLOUDS CENTRAL NC SHOULD REMAIN DRY ON TUESDAY.-ELLIS TUE NIGHT THROUGH WED NIGHT: A PROGRESSIVE PATTERN ALOFT WILL BE IN TRANSITION DURING THE MIDDLE OF THE WEEK AS A HIGHLY AMPLIFIED TROUGH ALOFT COMPRISED OF S/W ENERGY MIGRATES FROM THE FRONT RANGE OF THE ROCKIES TO THE EAST COAST. THIS TROUGH WILL DRIVE A STRONG FRONTAL ZONE...ONE FED BY STRONG MOISTURE TRANSPORT OFF THE GOM -- CHARACTERIZED BY PRECIPITABLE WATER VALUES AROUND 1.5 INCHES OR 2-3 SIGMAS ABOVE AVERAGE -- THROUGH CENTRAL NC WED EVENING. WARM AND BREEZY SOUTHWESTERLY FLOW IN ADVANCE OF THE FRONT WILL SEND TEMPERATURES INTO THE UPPER 60S WEST TO MIDDLE 70S EAST. WIDESPREAD SOAKING SHOWERS WILL ACCOMPANY THE FRONTAL ZONE...WITH PRECIPITATION AMOUNTS EXPECTED TO RANGE BETWEEN A HALF INCH AND ONE INCH...HIGHEST OVER THE WESTERN PIEDMONT...WHERE FORCING FOR ASCENT WILL BE MAXIMIZED BY THE LIFTING SOUTHERN PORTION OF THE TROUGH ALOFT. WHILE DEEP AND LOW LEVEL SHEAR WILL BE QUITE STRONG...WEAK LAPSE RATES ALOFT SUGGEST INSTABILITY WILL BE WEAK TO ABSENT...SO FORCING FOR ASCENT WILL NEED TO BE SUFFICIENTLY STRONG AND CONCENTRATED TO SUPPORT A STRONGLY FORCED/SHALLOW CONVECTIVE LINE ALONG THE FRONT. EVEN IF THAT WERE TO OCCUR...THE CONVECTIVE LINE WOULD BE DEVOID OF LIGHTNING...SO THUNDER WILL BE KEPT OUT OF THE FORECAST. HOWEVER...MOMENTUM TRANSPORT FROM BOWING LINE SEGMENTS WOULD BE CAPABLE OF PRODUCING 40-60 KT WIND GUSTS. ANY TORNADIC POTENTIAL WILL BE LOW..DESPITE FAVORABLE SHEAR PROFILES...OWING TO EH LACK OF INSTABILITY. HAVE SLOWED THE ARRIVAL AND DEPARTURE OF THE SHOWERS BY ABOUT SIX HOURS IN THE GRIDDED/TEXT FORECAST...CENTERED DURING THE EVENING HOURS. && .LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 335 AM MONDAY... STRONG CAA BEHIND THE FRONT WILL RESULT IN TEMPERATURES THU ABOUT 20 DEGREES COOLER THAN THOSE OF WED. ANOTHER ARCTIC HIGH WILL HEAD TOWARD OUR REGION FRI-SAT...LED SOUTHEASTWARD BY A CLIPPER-TYPE WAVE AND ACCOMPANYING SURFACE COLD FRONT ON FRI. MODEL CROSS SECTIONS INDICATE SUFFICIENT LIFT AND SATURATION TO GENERATE SNOW FROM THE NORTHERN NC PIEDMONT NORTHWARD THROUGH VA...BUT A DEEP AND DRY SUB-CLOUD LAYER SHOULD RESULT IN ONLY VIRGA OR A FEW FLURRIES/SPRINKLES NORTH OF HIGHWAY 64 FRI MORNING THROUGH EARLY AFTERNOON...SLIGHTLY LATER THAN EARLIER PROJECTIONS. OPPOSED BY STRONG CAA AND A BRISK NORTHWESTERLY WIND ON FRI...TEMPERATURES WILL STRUGGLE TO REACH 40 DEGREES ACROSS THE NORTHERN PIEDMONT...TO UPPER 40S TOWARD THE SC LINE. THE CENTER OF THE HIGH WILL DRIFT OVERHEAD BY SAT MORNING...WHICH SUGGESTS EXCELLENT RADIATIONAL COOLING WILL BE LIKELY...HINDERED ONLY BY CIRRUS ASSOCIATED WITH ANOTHER DISTURBANCE IN NW FLOW ALOFT. PROJECTED LOW LEVEL THICKNESS VALUES AROUND 1370 METERS SAT MORNING SUGGEST LOWS IN THE UPPER TEENS TO LOWER 20S...WITH HIGHS IN THE LOWER TO MIDDLE 40S ON SAT. ANOTHER CLIPPER-TYPE LOW WILL CROSS THE MIDDLE ATLANTIC SAT NIGHT...BEFORE DEEPENING OFF THE NEW ENGLAND COAST ON SUN. ASSOCIATED PRECIPITATION IS ACCORDINGLY EXPECTED TO OCCUR UPWIND OF THE NC BLUE RIDGE...AND NORTH OF THE VA STATE LINE. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... AS OF 630 AM MONDAY... 24 HOUR TAF PERIOD: PATCHY LIGHT RAIN OR DRIZZLE WILL CONTINUE AT MOST LOCATIONS THIS MORNING WITH KINT AND KGSO ENDING WITHIN THE HOUR. KFAY COULD SEE SOME LIGHT DRIZZLE BUT KRDU AND KRWI WILL SEE THE MOST PRECIPITATION THIS MORNING. WITH TEMPERATURES RIGHT AROUND FREEZING...FREEZING RAIN IS STILL NOT OUT OF THE QUESTION...MOST LIKELY AT KRWI. OTHERWISE LIGHT SOUTHERLY TO SOUTHWESTERLY FLOW WILL TAKE OVER TODAY. SOME MVFR/IFR CEILINGS OUT THERE THIS MORNING SHOULD LIFT TO VFR EARLY THIS AFTERNOON...HOWEVER CLOUD COVER WILL CONTINUE THIS AFTERNOON WITH CEILINGS AGAIN DETERIORATING LATE THIS AFTERNOON INTO THE EVENING. WHILE CONDITIONS ARE FAVORABLE FOR WIDESPREAD FOG OVERNIGHT MONDAY INTO TUESDAY...SOME HIGHER WIND SPEEDS COULD CREATE MORE OF A LOW STRATUS SITUATION WITH LIFR CEILINGS EXPECTED EVERYWHERE. VISIBILITIES MAY COME DOWN VARYING AMOUNTS BUT THAT WONT MATTER GIVEN CIGS ARE EXPECTED TO FALL TO LIFR. LOOKING AHEAD: FOG AND OR LOW STRATUS WILL BE LIKELY TUESDAY MORNING. ADVERSE CONDITIONS ARE ALSO LIKELY WEDNESDAY INTO THURSDAY WITH THE PASSAGE OF A FRONTAL SYSTEM. ON FRIDAY...NORTHERN SITES MAY HAVE A CHANCE FOR SOME LIGHT SNOW SHOWERS. && .RAH WATCHES/WARNINGS/ADVISORIES... FREEZING RAIN ADVISORY UNTIL 9 AM EST THIS MORNING FOR NCZ007>011-021>028-038>041-043. && $$ SYNOPSIS...MWS NEAR TERM...ELLIS SHORT TERM...ELLIS/MWS LONG TERM...MWS AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
338 AM EST MON JAN 28 2013 .SYNOPSIS... WARM AND MOIST SOUTHWESTERLY FLOW WILL RIDE ATOP A LINGERING RIDGE OF COOL SURFACE HIGH PRESSURE OVER THE CAROLINAS THROUGH TONIGHT. THE WARM SOUTHWESTERLY FLOW WILL REACH THE SURFACE BY TUESDAY AFTERNOON...AND CONTINUE THROUGH WEDNESDAY...IN ADVANCE OF A STRONG COLD FRONT THAT WILL CROSS THE MIDDLE ATLANTIC AND CAROLINAS WEDNESDAY EVENING. && .NEAR TERM /THROUGH TONIGHT/... AS OF 230 AM MONDAY... MONDAY AND MONDAY NIGHT: ...FREEZING RAIN ADVISORY EXTENDED TO INCLUDE COUNTIES IN THE NORTHEASTERN PIEDMONT OF NC THROUGH 9AM... HAVE EXTENDED THE FREEZING RAIN ADVISORY THROUGH THE NORTHEASTERN COUNTIES BASED ON THE FACT THAT BOTH CURRENT TEMPERATURES AND WET BULB TEMPERATURES REMAIN BELOW FREEZING IN THIS AREA...ALONG THE AXIS OF THE DRY AIR SURFACE RIDGE...AND SINCE CURRENT RADAR TRENDS AND CURRENT RUNS OF THE RAP/RUC MODEL SHOW THE AREA OF PRECIPITATION EXPANDING FROM THE COASTAL PLAIN TO THE WEST OF THE TRIAD WILL CONTINUE EASTWARD ACROSS THE CWA IMPACTING THE NORTHEASTERN COUNTIES THROUGH 9 AM. CURRENT SURFACE ANALYSIS SHOWS SURFACE HIGH PRESSURE SET UP OVER THE TIDEWATER VIRGINIA REGION. THIS HIGH IS RESPONSIBLE FOR SUBFREEZING TEMPERATURES IN EASTERN NORTH CAROLINA WITH NORTHEASTERLY FLOW. FURTHER WEST HOWEVER...RETURN FLOW AROUND THE HIGH HAS KEPT TEMPERATURES MAINLY IN THE MIDDLE 30S. CURRENT RADAR TRENDS SHOW REFLECTIVITIES SPLITTING WITH ONE AREA MOVING SWIFTLY ACROSS THE NORTHERN TIER OF THE CWA WITH ANOTHER BAND TO THE SOUTH. THE OCCURRENCE OF FREEZING RAIN IS VERY QUESTIONABLE AT THIS POINT DUE TO A COUPLE OF FACTORS. CLOUD COVER AND SOUTHERLY FLOW IN THE WEST HAVE KEPT TEMPERATURES UP. WHILE SOME LIGHT RAIN OR DRIZZLE MAY BE LIKELY...FREEZING RAIN IS NOT AS LIKELY UNLESS ENOUGH WETBULBING OCCURS TO BRING TEMPERATURES BACK DOWN TO FREEZING. FURTHER TO THE EAST...TEMPERATURES HAVE ALREADY ACHIEVED THE FREEZING MARK BUT AS THE HIGH SLIDES EASTWARD ALONG WITH IT WILL COME THE CLOUDS AND SOUTHERLY FLOW AND A RISE IN THE SURFACE TEMPERATURES. AT THIS POINT THE MOST LIKELY AREA FOR FREEZING RAIN WILL BE THE NORTHEAST BECAUSE EVEN IF TEMPERATURES RISE BACK ABOVE FREEZING...ONCE PRECIPITATION STARTS WETBULBING SHOULD BRING IT BACK DOWN. WITH A NORTH TO SOUTH ORIENTED BAND MOVING ACROSS THE NORTH...ANY PRECIPITATION THAT DOES OCCUR SHOULD ONLY LAST AN HOUR OR TWO MAXIMUM. IT IS LIKELY THAT THE FREEZING RAIN ADVISORY WILL HAVE TO BE TRIMMED BACK FROM WEST TO EAST OR PERHAPS CANCELLED ALL TOGETHER AS CONDITIONS WARRANT. CURRENT RAP SOUNDINGS INDICATE THAT MANY SITES WILL REMAIN ABOVE FREEZING WITH THE EXCEPTION OF THOSE IN THE FAR EASTERN PORTIONS OF THE AREA. WHETHER OR NOT PRECIPITATION ARRIVES IN TIME TO TAKE ADVANTAGE OF THOSE LOWER TEMPERATURES REMAINS TO BE SEEN. REGARDLESS...EXPECT PATCHY SPRINKLES OR LIGHT RAIN THROUGH SUNRISE WITH ISOLATED PATCHES OF FREEZING RAIN MOST LIKELY IN THE NORTHEAST. MINIMUM TEMPERATURES HAVE ALREADY BOTTOMED OUT IN MOST CASES MID TO UPPER 20S EAST AND LOWER 30S WEST. ANY ONGOING PRECIPITATION SHOULD TAPER OFF MONDAY MORNING WITH A SOME FOG POSSIBLE IN LOCALIZED AREAS. SKIES WILL REMAIN OVERCAST FOR MOST OF THE DAY ON MONDAY. COMBINING THIS ALONG WITH AFTERNOON THICKNESS VALUES IN THE MID 1300S SHOULD KEEP MAXIMUM TEMPERATURES DOWN ON MONDAY...MID 40S NORTHWEST TO UPPER 40S TO LOWER 50S IN THE SOUTHEAST. SOME LIGHT RAIN OR DRIZZLE IS POSSIBLE THROUGHOUT MUCH OF THE DAY ON MONDAY. CEILINGS WILL GRADUALLY COME DOWN MOST LIKELY TO IFR/LIFR LATER MONDAY NIGHT INTO TUESDAY MORNING. WITH BOTH TEMPERATURES AND DEWPOINTS IN THE MID 40S TUESDAY NIGHT...CONDITIONS ARE FAVORABLE FOR A WIDESPREAD FOG EVENT. FORECAST SOUNDINGS ARE HINTING AT THIS PROBABILITY AND WILL CONTINUE TO MONITOR THE SITUATION FOR A POSSIBLE DENSE FOG ADVISORY MONDAY NIGHT INTO TUESDAY MORNING. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 230 AM MONDAY... TUESDAY: ON TUESDAY THE SURFACE HIGH CONTINUES TO MOVE SOUTHEASTWARD OFF THE SOUTH CAROLINA COAST. WITH A LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT APPROACHING FROM THE WEST...CENTRAL NORTH CAROLINA WILL BE IN THE MIDDLE OF A WARM AIR ADVECTION REGIME WHICH WILL INCREASE IN STRENGTH AS THE DAY GOES ON. EXPECT TEMPERATURES DRAMATICALLY HIGHER ON TUESDAY WITH MID 60S NORTHWEST TO NEAR 70 IN THE SOUTHEAST. EXPECT SOME THINNING OF CLOUDS IN THE AFTERNOON BUT OVERALL SHOULD REMAIN PARTLY TO MOSTLY CLOUDY IF NOT OVERCAST. DESPITE THE CLOUDS CENTRAL NC SHOULD REMAIN DRY ON TUESDAY.-ELLIS TUE NIGHT THROUGH WED NIGHT: A PROGRESSIVE PATTERN ALOFT WILL BE IN TRANSITION DURING THE MIDDLE OF THE WEEK AS A HIGHLY AMPLIFIED TROUGH ALOFT COMPRISED OF S/W ENERGY MIGRATES FROM THE FRONT RANGE OF THE ROCKIES TO THE EAST COAST. THIS TROUGH WILL DRIVE A STRONG FRONTAL ZONE...ONE FED BY STRONG MOISTURE TRANSPORT OFF THE GOM -- CHARACTERIZED BY PRECIPITABLE WATER VALUES AROUND 1.5 INCHES OR 2-3 SIGMAS ABOVE AVERAGE -- THROUGH CENTRAL NC WED EVENING. WARM AND BREEZY SOUTHWESTERLY FLOW IN ADVANCE OF THE FRONT WILL SEND TEMPERATURES INTO THE UPPER 60S WEST TO MIDDLE 70S EAST. WIDESPREAD SOAKING SHOWERS WILL ACCOMPANY THE FRONTAL ZONE...WITH PRECIPITATION AMOUNTS EXPECTED TO RANGE BETWEEN A HALF INCH AND ONE INCH...HIGHEST OVER THE WESTERN PIEDMONT...WHERE FORCING FOR ASCENT WILL BE MAXIMIZED BY THE LIFTING SOUTHERN PORTION OF THE TROUGH ALOFT. WHILE DEEP AND LOW LEVEL SHEAR WILL BE QUITE STRONG...WEAK LAPSE RATES ALOFT SUGGEST INSTABILITY WILL BE WEAK TO ABSENT...SO FORCING FOR ASCENT WILL NEED TO BE SUFFICIENTLY STRONG AND CONCENTRATED TO SUPPORT A STRONGLY FORCED/SHALLOW CONVECTIVE LINE ALONG THE FRONT. EVEN IF THAT WERE TO OCCUR...THE CONVECTIVE LINE WOULD BE DEVOID OF LIGHTNING...SO THUNDER WILL BE KEPT OUT OF THE FORECAST. HOWEVER...MOMENTUM TRANSPORT FROM BOWING LINE SEGMENTS WOULD BE CAPABLE OF PRODUCING 40-60 KT WIND GUSTS. ANY TORNADIC POTENTIAL WILL BE LOW..DESPITE FAVORABLE SHEAR PROFILES...OWING TO EH LACK OF INSTABILITY. HAVE SLOWED THE ARRIVAL AND DEPARTURE OF THE SHOWERS BY ABOUT SIX HOURS IN THE GRIDDED/TEXT FORECAST...CENTERED DURING THE EVENING HOURS. && .LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 335 AM MONDAY... STRONG CAA BEHIND THE FRONT WILL RESULT IN TEMPERATURES THU ABOUT 20 DEGREES COOLER THAN THOSE OF WED. ANOTHER ARCTIC HIGH WILL HEAD TOWARD OUR REGION FRI-SAT...LED SOUTHEASTWARD BY A CLIPPER-TYPE WAVE AND ACCOMPANYING SURFACE COLD FRONT ON FRI. MODEL CROSS SECTIONS INDICATE SUFFICIENT LIFT AND SATURATION TO GENERATE SNOW FROM THE NORTHERN NC PIEDMONT NORTHWARD THROUGH VA...BUT A DEEP AND DRY SUB-CLOUD LAYER SHOULD RESULT IN ONLY VIRGA OR A FEW FLURRIES/SPRINKLES NORTH OF HIGHWAY 64 FRI MORNING THROUGH EARLY AFTERNOON...SLIGHTLY LATER THAN EARLIER PROJECTIONS. OPPOSED BY STRONG CAA AND A BRISK NORTHWESTERLY WIND ON FRI...TEMPERATURES WILL STRUGGLE TO REACH 40 DEGREES ACROSS THE NORTHERN PIEDMONT...TO UPPER 40S TOWARD THE SC LINE. THE CENTER OF THE HIGH WILL DRIFT OVERHEAD BY SAT MORNING...WHICH SUGGESTS EXCELLENT RADIATIONAL COOLING WILL BE LIKELY...HINDERED ONLY BY CIRRUS ASSOCIATED WITH ANOTHER DISTURBANCE IN NW FLOW ALOFT. PROJECTED LOW LEVEL THICKNESS VALUES AROUND 1370 METERS SAT MORNING SUGGEST LOWS IN THE UPPER TEENS TO LOWER 20S...WITH HIGHS IN THE LOWER TO MIDDLE 40S ON SAT. ANOTHER CLIPPER-TYPE LOW WILL CROSS THE MIDDLE ATLANTIC SAT NIGHT...BEFORE DEEPENING OFF THE NEW ENGLAND COAST ON SUN. ASSOCIATED PRECIPITATION IS ACCORDINGLY EXPECTED TO OCCUR UPWIND OF THE NC BLUE RIDGE...AND NORTH OF THE VA STATE LINE. && .AVIATION /09Z MONDAY THROUGH FRIDAY/... AS OF 1220 AM MONDAY... 24 HOUR TAF PERIOD: TRICKY FORECAST OVERNIGHT TONIGHT AS RADAR CURRENTLY SHOWING LIGHT PRECIPITATION MOVING ACROSS THE FOOTHILLS AND INTO THE WESTERN PIEDMONT OF NORTH CAROLINA. THIS COMBINED WITH SUB FREEZING TEMPERATURES COULD GIVE A CHANCE FOR SOME LIGHT FREEZING RAIN FROM WEST TO EAST ACROSS THE AREA. WHILE THERE IS A CHANCE THAT KINT AND KGSO COULD GET SOME LIGHT RAIN BETWEEN 6 AND 8Z...CLOUD COVER HAS KEPT TEMPERATURES IN THE MID 30S. IN ADDITION THE HEAVIER RETURNS ON THE RADAR HAVE BEGUN TO MOVE SOUTH OF KINT AND KGSO AND THEREFORE ONLY A THIN BAND OF PRECIPITATION ORIENTED NORTH TO SOUTH WILL CROSS THE AREA...MOST LIKELY WITH TEMPERATURES ABOVE FREEZING. FURTHER EAST WHERE THERE IS LESS CLOUD COVER TEMPERATURES HAVE ALREADY DIPPED TOWARDS THE FREEZING MARK WITH KRDU AND KFAY ON THE VERGE OF FREEZING AND KRWI ALREADY REPORTING 26 DEGREES. WITH RETURNS MOVING TO THE SOUTH...THERE IS A GROWING CHANCE OF SOME FREEZING RAIN AT KFAY...BUT THE ONSET OF OVERCAST SKIES HAS ELEVATED THE TEMPERATURE IN THE LAST COUPLE OF HOURS. SAME IS TRUE FOR KRDU. WILL COVER ALL FREEZING RAIN WITH TEMPO GROUPS IN THE TAF AND HAVE LEFT IT OUT OF KRWI AT THIS TIME BECAUSE OF WEAKENING RADAR TRENDS. OTHERWISE EXPECT LIGHT SOUTHWESTERLY FLOW WITH CEILING GRADUALLY COMING DOWN THROUGHOUT THE TAF PERIOD WITH MVFR AND IFR CEILINGS LIKELY BY EARLY TUESDAY MORNING. LOOKING AHEAD: FOG AND OR LOW STRATUS WILL BE LIKELY TUESDAY MORNING. ADVERSE CONDITIONS ARE ALSO LIKELY WEDNESDAY INTO THURSDAY WITH THE PASSAGE OF A FRONTAL SYSTEM. ON FRIDAY...NORTHERN SITES MAY HAVE A CHANCE FOR SOME LIGHT SNOW SHOWERS. && .RAH WATCHES/WARNINGS/ADVISORIES... FREEZING RAIN ADVISORY UNTIL 9 AM EST THIS MORNING FOR NCZ007>011-021>028-038>041-043. && $$ SYNOPSIS...MWS NEAR TERM...ELLIS SHORT TERM...ELLIS/MWS LONG TERM...MWS AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
332 AM EST MON JAN 28 2013 .SYNOPSIS... WARM AND MOIST SOUTHWESTERLY FLOW WILL RIDE ATOP A LINGERING RIDGE OF COOL SURFACE HIGH PRESSURE OVER THE CAROLINAS THROUGH TONIGHT. THE WARM SOUTHWESTERLY FLOW WILL REACH THE SURFACE BY TUESDAY AFTERNOON...AND CONTINUE THROUGH WEDNESDAY...IN ADVANCE OF A STRONG COLD FRONT THAT WILL CROSS THE MIDDLE ATLANTIC AND CAROLINAS WEDNESDAY EVENING. && .NEAR TERM /THROUGH TONIGHT/... AS OF 230 AM MONDAY... MONDAY AND MONDAY NIGHT: ...FREEZING RAIN ADVISORY EXTENDED TO INCLUDE COUNTIES IN THE NORTHEASTERN PIEDMONT OF NC THROUGH 9AM... HAVE EXTENDED THE FREEZING RAIN ADVISORY THROUGH THE NORTHEASTERN COUNTIES BASED ON THE FACT THAT CURRENT TEMPERATURES REMAIN BELOW FREEZING AND SURFACE WETBULBS CONTINUE TO BE BELOW ZERO IN THIS AREA. CURRENT RADAR TRENDS AND CURRENT RUN OF THE RAP/RUC MODEL SHOW AREA OF PRECIPITATION CURRENTLY ENTERING THE TRIAD TO CONTINUE EASTWARD ACROSS THE CWA IMPACTING THE NORTHEASTERN COUNTIES SOMETIME BETWEEN 6 AND 9AM. CURRENT SURFACE ANALYSIS SHOWS SURFACE HIGH PRESSURE SET UP OVER THE TIDEWATER VIRGINIA REGION. THIS HIGH IS RESPONSIBLE FOR SUBFREEZING TEMPERATURES IN EASTERN NORTH CAROLINA WITH NORTHEASTERLY FLOW. FURTHER WEST HOWEVER...RETURN FLOW AROUND THE HIGH HAS KEPT TEMPERATURES MAINLY IN THE MIDDLE 30S. CURRENT RADAR TRENDS SHOW REFLECTIVITIES SPLITTING WITH ONE AREA MOVING SWIFTLY ACROSS THE NORTHERN TIER OF THE CWA WITH ANOTHER BAND TO THE SOUTH. THE OCCURRENCE OF FREEZING RAIN IS VERY QUESTIONABLE AT THIS POINT DUE TO A COUPLE OF FACTORS. CLOUD COVER AND SOUTHERLY FLOW IN THE WEST HAVE KEPT TEMPERATURES UP. WHILE SOME LIGHT RAIN OR DRIZZLE MAY BE LIKELY...FREEZING RAIN IS NOT AS LIKELY UNLESS ENOUGH WETBULBING OCCURS TO BRING TEMPERATURES BACK DOWN TO FREEZING. FURTHER TO THE EAST...TEMPERATURES HAVE ALREADY ACHIEVED THE FREEZING MARK BUT AS THE HIGH SLIDES EASTWARD ALONG WITH IT WILL COME THE CLOUDS AND SOUTHERLY FLOW AND A RISE IN THE SURFACE TEMPERATURES. AT THIS POINT THE MOST LIKELY AREA FOR FREEZING RAIN WILL BE THE NORTHEAST BECAUSE EVEN IF TEMPERATURES RISE BACK ABOVE FREEZING...ONCE PRECIPITATION STARTS WETBULBING SHOULD BRING IT BACK DOWN. WITH A NORTH TO SOUTH ORIENTED BAND MOVING ACROSS THE NORTH...ANY PRECIPITATION THAT DOES OCCUR SHOULD ONLY LAST AN HOUR OR TWO MAXIMUM. IT IS LIKELY THAT THE FREEZING RAIN ADVISORY WILL HAVE TO BE TRIMMED BACK FROM WEST TO EAST OR PERHAPS CANCELLED ALL TOGETHER AS CONDITIONS WARRANT. CURRENT RAP SOUNDINGS INDICATE THAT MANY SITES WILL REMAIN ABOVE FREEZING WITH THE EXCEPTION OF THOSE IN THE FAR EASTERN PORTIONS OF THE AREA. WHETHER OR NOT PRECIPITATION ARRIVES IN TIME TO TAKE ADVANTAGE OF THOSE LOWER TEMPERATURES REMAINS TO BE SEEN. REGARDLESS...EXPECT PATCHY SPRINKLES OR LIGHT RAIN THROUGH SUNRISE WITH ISOLATED PATCHES OF FREEZING RAIN MOST LIKELY IN THE NORTHEAST. MINIMUM TEMPERATURES HAVE ALREADY BOTTOMED OUT IN MOST CASES MID TO UPPER 20S EAST AND LOWER 30S WEST. ANY ONGOING PRECIPITATION SHOULD TAPER OFF MONDAY MORNING WITH A SOME FOG POSSIBLE IN LOCALIZED AREAS. SKIES WILL REMAIN OVERCAST FOR MOST OF THE DAY ON MONDAY. COMBINING THIS ALONG WITH AFTERNOON THICKNESS VALUES IN THE MID 1300S SHOULD KEEP MAXIMUM TEMPERATURES DOWN ON MONDAY...MID 40S NORTHWEST TO UPPER 40S TO LOWER 50S IN THE SOUTHEAST. SOME LIGHT RAIN OR DRIZZLE IS POSSIBLE THROUGHOUT MUCH OF THE DAY ON MONDAY. CEILINGS WILL GRADUALLY COME DOWN MOST LIKELY TO IFR/LIFR LATER MONDAY NIGHT INTO TUESDAY MORNING. WITH BOTH TEMPERATURES AND DEWPOINTS IN THE MID 40S TUESDAY NIGHT...CONDITIONS ARE FAVORABLE FOR A WIDESPREAD FOG EVENT. FORECAST SOUNDINGS ARE HINTING AT THIS PROBABILITY AND WILL CONTINUE TO MONITOR THE SITUATION FOR A POSSIBLE DENSE FOG ADVISORY MONDAY NIGHT INTO TUESDAY MORNING. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 230 AM MONDAY... TUESDAY: ON TUESDAY THE SURFACE HIGH CONTINUES TO MOVE SOUTHEASTWARD OFF THE SOUTH CAROLINA COAST. WITH A LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT APPROACHING FROM THE WEST...CENTRAL NORTH CAROLINA WILL BE IN THE MIDDLE OF A WARM AIR ADVECTION REGIME WHICH WILL INCREASE IN STRENGTH AS THE DAY GOES ON. EXPECT TEMPERATURES DRAMATICALLY HIGHER ON TUESDAY WITH MID 60S NORTHWEST TO NEAR 70 IN THE SOUTHEAST. EXPECT SOME THINNING OF CLOUDS IN THE AFTERNOON BUT OVERALL SHOULD REMAIN PARTLY TO MOSTLY CLOUDY IF NOT OVERCAST. DESPITE THE CLOUDS CENTRAL NC SHOULD REMAIN DRY ON TUESDAY.-ELLIS TUESDAY NIGHT: THE MSLP GRADIENT TIGHTENS TUESDAY NIGHT OVER NC WITH THE GROWING CONTRAST BETWEEN THE OFFSHORE HIGH AND INCOMING COLD FRONT. LOW LEVEL WARM AIR ADVECTION AND CLOUDS WILL TRANSLATE INTO MILD PREFRONTAL LOWS... AND HAVE RAISED THEM SEVERAL DEGREES TO 54-61. EXPECT PATCHY LIGHT SHOWERS TO DEVELOP OVERNIGHT MAINLY IN THE WEST WITH INCREASING PRECIP WATER TO OVER 1 INCH AND DEEPENING MOIST UPGLIDE. FOR WEDNESDAY/WEDNESDAY NIGHT: WINDY/WET/WARM FOLLOWED BY A STARK COOLDOWN. THE RECENT NAM RUNS HAVE TRENDED MUCH FASTER WITH THE INCOMING FRONT AND ASSOCIATED WARM-CONVEYOR BAND OF SHOWERS... WHILE THE MORE CONSISTENT GFS HAS SHOWN JUST A SLIGHT SLOWING TREND AND AGREES WITH THE ECMWF TIMING. CONSENSUS OF THE GFS/ECMWF BRINGS IN JUST LIGHT SCATTERED SHOWERS THROUGH WEDNESDAY MORNING... WITH THE MORE NUMEROUS AND HEAVIER SHOWERS ARRIVING IN THE AFTERNOON THROUGH EVENING SWEEPING WEST TO EAST. PRECIP WATER VALUES ARE EXPECTED TO EXCEED 1.5 INCHES... HIGHLY ANOMALOUS FOR LATE JANUARY (IN THE 99TH PERCENTILE)... AND FORECAST SOUNDINGS DEPICT A DEEP WARM LAYER (LCL TO FREEZING OF 3.0-3.2 KM)... THUS HEAVY DOWNPOURS ARE POSSIBLE. HAVE RAISED POPS TO CATEGORICAL... FOCUSING AFTER 18Z IN THE PIEDMONT/WRN SANDHILLS AND AFTER 23Z IN THE ERN SANDHILLS AND COASTAL PLAIN. THE VERTICAL PROFILE BECOMES NEARLY MOIST ADIABATIC AT BEST... AND WITH THE MARGINAL LAPSE RATES AND LACK OF INSTABILITY IN THE MIXED PHASE REGION ALOFT... WILL NOT INCLUDE THUNDER AT THIS TIME DUE TO ITS EXPECTED SPARSITY BUT THIS MAY NEED TO BE ADDED TO LATER FORECASTS. DESPITE THE LACK OF DOWNWARD MOMENTUM THE BOUNDARY LAYER WINDS ALONE FAVOR QUITE A WINDY DAY... SUSTAINED 15-20 MPH GUSTING TO AROUND 30 MPH... AND WOULD NOT BE AT ALL SURPRISED TO SEE THESE NUMBERS COME UP A BIT IN LATER FORECASTS TOO... ONCE WE CAN OBSERVE UPSTREAM PREFRONTAL CONDITIONS. EVEN WITH THE MODERATE TO HEAVY SHOWERS... WE SHOULD SEE STORM TOTAL QPF AMOUNTS OF A THIRD TO HALF INCH... LIMITED BY THE SPEED OF THIS SYSTEM. HIGHS FROM 64 NW TO 76 SE. LOWS 36-46 WITH THE FRONT SHIFTING OFF THE COAST AFTER MIDNIGHT... AND SKIES CLEARING LATE. -GIH && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 225 PM SUNDAY... FOR THURSDAY THROUGH FRIDAY: THE DAMPENING LONGWAVE TROUGH AXIS WILL BE HEADING EASTWARD OFF THE COAST THURSDAY MORNING... ALTHOUGH EYES THEN TURN TO A STRONG MID LEVEL SHORTWAVE TROUGH DROPPING SOUTHWARD INTO THE UPPER MIDWEST EARLY THURSDAY... POISED TO SWING THROUGH THE MIDATLANTIC REGION ON FRIDAY. LOW LEVEL THICKNESSES PLUNGE FROM LATE WEDNESDAY INTO THURSDAY MORNING... FROM 55-60 METERS ABOVE NORMAL DOWN TO NEAR OR JUST UNDER NORMAL AS MODIFIED HIGH PRESSURE BUILDS EASTWARD OVER THE GULF COAST. WE SHOULD STAY A LITTLE BREEZY THROUGH EARLY THURSDAY. HIGHS 44-55 WITH MOSTLY SUNNY SKIES. EXPECT INCREASING MID AND HIGH CLOUDS THURSDAY NIGHT AS THE ALREADY-SWIFT UPPER LEVEL FLOW STRENGTHENS ANEW TO 140+ KTS IN RESPONSE TO THE APPROACHING ENERGY ALOFT. LOWS IN THE LOWER 30S. AS ONE MIGHT EXPECT AT THIS RANGE... THE GFS/ECMWF DIFFER A BIT WITH REGARDS TO TIMING AND STRENGTH OF THE VORTICITY MAXIMUM THAT CROSSES THE AREA FRIDAY... BUT THIS PATTERN WITH DECENT DYNAMIC FORCING... COLD AIR IN PLACE... AND BACKING LOW LEVEL WINDS ALLOWING A TRANSPORT OF MOISTURE... DOES SUPPORT AT LEAST A SMALL CHANCE OF A QUICK SNOW SHOWER... AND IF THE ECMWF`S STRONGER WAVE IS CORRECT... SCATTERED COVERAGE COULD BE ACHIEVED. WILL PLACE A SLIGHT CHANCE OF A SNOW SHOWER ALONG/NORTH OF HIGHWAY 64. WITH THICKNESSES FRIDAY RUNNING 20 METER BELOW NORMAL AND SCATTERED TO BROKEN COLD AIR CONVECTIVE CLOUDS... EXPECT HIGHS OF JUST 36-40 IN THE NORTH AND 40-46 SOUTHEAST. FOR FRIDAY NIGHT THROUGH SUNDAY: AS A YUKON-SOURCE HIGH BUILDS OVERHEAD FROM THE NNW WITH THE POLAR WESTERLIES EXTENDING WELL DOWN TO OUR LATITUDE... EXPECT FAIR TO PARTLY CLOUDY SKIES AND CHILLY TEMPS FRIDAY NIGHT INTO SATURDAY. ANOTHER MID LEVEL WAVE SWINGING THROUGH THE MIDATLANTIC AND NORTHEAST SATURDAY AFTERNOON/NIGHT WILL BRING ANOTHER CLIPPER FRONT THROUGH THE REGION... REINFORCING THE BELOW-NORMAL TEMPS. NO POPS FOR THIS TIME FRAME YET BUT ANOTHER ROUND OF ISOLATED SNOW SHOWERS FOR THE NORTHERN BORDER COUNTIES IS CERTAINLY POSSIBLE EARLY SUNDAY. LOWS IN THE 20S AND HIGHS IN THE LOW-MID 40S. -GIH && .AVIATION /09Z MONDAY THROUGH FRIDAY/... AS OF 1220 AM MONDAY... 24 HOUR TAF PERIOD: TRICKY FORECAST OVERNIGHT TONIGHT AS RADAR CURRENTLY SHOWING LIGHT PRECIPITATION MOVING ACROSS THE FOOTHILLS AND INTO THE WESTERN PIEDMONT OF NORTH CAROLINA. THIS COMBINED WITH SUB FREEZING TEMPERATURES COULD GIVE A CHANCE FOR SOME LIGHT FREEZING RAIN FROM WEST TO EAST ACROSS THE AREA. WHILE THERE IS A CHANCE THAT KINT AND KGSO COULD GET SOME LIGHT RAIN BETWEEN 6 AND 8Z...CLOUD COVER HAS KEPT TEMPERATURES IN THE MID 30S. IN ADDITION THE HEAVIER RETURNS ON THE RADAR HAVE BEGUN TO MOVE SOUTH OF KINT AND KGSO AND THEREFORE ONLY A THIN BAND OF PRECIPITATION ORIENTED NORTH TO SOUTH WILL CROSS THE AREA...MOST LIKELY WITH TEMPERATURES ABOVE FREEZING. FURTHER EAST WHERE THERE IS LESS CLOUD COVER TEMPERATURES HAVE ALREADY DIPPED TOWARDS THE FREEZING MARK WITH KRDU AND KFAY ON THE VERGE OF FREEZING AND KRWI ALREADY REPORTING 26 DEGREES. WITH RETURNS MOVING TO THE SOUTH...THERE IS A GROWING CHANCE OF SOME FREEZING RAIN AT KFAY...BUT THE ONSET OF OVERCAST SKIES HAS ELEVATED THE TEMPERATURE IN THE LAST COUPLE OF HOURS. SAME IS TRUE FOR KRDU. WILL COVER ALL FREEZING RAIN WITH TEMPO GROUPS IN THE TAF AND HAVE LEFT IT OUT OF KRWI AT THIS TIME BECAUSE OF WEAKENING RADAR TRENDS. OTHERWISE EXPECT LIGHT SOUTHWESTERLY FLOW WITH CEILING GRADUALLY COMING DOWN THROUGHOUT THE TAF PERIOD WITH MVFR AND IFR CEILINGS LIKELY BY EARLY TUESDAY MORNING. LOOKING AHEAD: FOG AND OR LOW STRATUS WILL BE LIKELY TUESDAY MORNING. ADVERSE CONDITIONS ARE ALSO LIKELY WEDNESDAY INTO THURSDAY WITH THE PASSAGE OF A FRONTAL SYSTEM. ON FRIDAY...NORTHERN SITES MAY HAVE A CHANCE FOR SOME LIGHT SNOW SHOWERS. && .RAH WATCHES/WARNINGS/ADVISORIES... FREEZING RAIN ADVISORY UNTIL 9 AM EST THIS MORNING FOR NCZ007>011-021>028-038>041-043. && $$ SYNOPSIS...MWS NEAR TERM...ELLIS SHORT TERM...ELLIS/HARTFIELD LONG TERM...HARTFIELD AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
237 AM EST MON JAN 28 2013 .SYNOPSIS... WARM AND MOIST SOUTHWESTERLY FLOW WILL RIDE ATOP A LINGERING RIDGE OF COOL SURFACE HIGH PRESSURE OVER THE CAROLINAS THROUGH TONIGHT. THE WARM SOUTHWESTERLY FLOW WILL REACH THE SURFACE BY TUESDAY AFTERNOON...AND CONTINUE THROUGH WEDNESDAY...IN ADVANCE OF A STRONG COLD FRONT THAT WILL CROSS THE MIDDLE ATLANTIC AND CAROLINAS WEDNESDAY EVENING. && .NEAR TERM /THROUGH MONDAY NIGHT/... AS OF 230 AM MONDAY... MONDAY AND MONDAY NIGHT: ...FREEZING RAIN ADVISORY REMAINS IN EFFECT THROUGH 9AM FOR THE NORTHERN PIEDMONT... CURRENT SURFACE ANALYSIS SHOWS SURFACE HIGH PRESSURE SET UP OVER THE TIDEWATER VIRGINIA REGION. THIS HIGH IS RESPONSIBLE FOR SUBFREEZING TEMPERATURES IN EASTERN NORTH CAROLINA WITH NORTHEASTERLY FLOW. FURTHER WEST HOWEVER...RETURN FLOW AROUND THE HIGH HAS KEPT TEMPERATURES MAINLY IN THE MIDDLE 30S. CURRENT RADAR TRENDS SHOW REFLECTIVITIES SPLITTING WITH ONE AREA MOVING SWIFTLY ACROSS THE NORTHERN TIER OF THE CWA WITH ANOTHER BAND TO THE SOUTH. THE OCCURRENCE OF FREEZING RAIN IS VERY QUESTIONABLE AT THIS POINT DUE TO A COUPLE OF FACTORS. CLOUD COVER AND SOUTHERLY FLOW IN THE WEST HAVE KEPT TEMPERATURES UP. WHILE SOME LIGHT RAIN OR DRIZZLE MAY BE LIKELY...FREEZING RAIN IS NOT AS LIKELY UNLESS ENOUGH WETBULBING OCCURS TO BRING TEMPERATURES BACK DOWN TO FREEZING. FURTHER TO THE EAST...TEMPERATURES HAVE ALREADY ACHIEVED THE FREEZING MARK BUT AS THE HIGH SLIDES EASTWARD ALONG WITH IT WILL COME THE CLOUDS AND SOUTHERLY FLOW AND A RISE IN THE SURFACE TEMPERATURES. AT THIS POINT THE MOST LIKELY AREA FOR FREEZING RAIN WILL BE THE NORTHEAST BECAUSE EVEN IF TEMPERATURES RISE BACK ABOVE FREEZING...ONCE PRECIPITATION STARTS WETBULBING SHOULD BRING IT BACK DOWN. WITH A NORTH TO SOUTH ORIENTED BAND MOVING ACROSS THE NORTH...ANY PRECIPITATION THAT DOES OCCUR SHOULD ONLY LAST AN HOUR OR TWO MAXIMUM. IT IS LIKELY THAT THE FREEZING RAIN ADVISORY WILL HAVE TO BE TRIMMED BACK FROM WEST TO EAST OR PERHAPS CANCELLED ALL TOGETHER AS CONDITIONS WARRANT. CURRENT RAP SOUNDINGS INDICATE THAT MANY SITES WILL REMAIN ABOVE FREEZING WITH THE EXCEPTION OF THOSE IN THE FAR EASTERN PORTIONS OF THE AREA. WHETHER OR NOT PRECIPITATION ARRIVES IN TIME TO TAKE ADVANTAGE OF THOSE LOWER TEMPERATURES REMAINS TO BE SEEN. REGARDLESS...EXPECT PATCHY SPRINKLES OR LIGHT RAIN THROUGH SUNRISE WITH ISOLATED PATCHES OF FREEZING RAIN MOST LIKELY IN THE NORTHEAST. MINIMUM TEMPERATURES HAVE ALREADY BOTTOMED OUT IN MOST CASES MID TO UPPER 20S EAST AND LOWER 30S WEST. ANY ONGOING PRECIPITATION SHOULD TAPER OFF MONDAY MORNING WITH A SOME FOG POSSIBLE IN LOCALIZED AREAS. SKIES WILL REMAIN OVERCAST FOR MOST OF THE DAY ON MONDAY. COMBINING THIS ALONG WITH AFTERNOON THICKNESS VALUES IN THE MID 1300S SHOULD KEEP MAXIMUM TEMPERATURES DOWN ON MONDAY...MID 40S NORTHWEST TO UPPER 40S TO LOWER 50S IN THE SOUTHEAST. SOME LIGHT RAIN OR DRIZZLE IS POSSIBLE THROUGHOUT MUCH OF THE DAY ON MONDAY. CEILINGS WILL GRADUALLY COME DOWN MOST LIKELY TO IFR/LIFR LATER MONDAY NIGHT INTO TUESDAY MORNING. WITH BOTH TEMPERATURES AND DEWPOINTS IN THE MID 40S TUESDAY NIGHT...CONDITIONS ARE FAVORABLE FOR A WIDESPREAD FOG EVENT. FORECAST SOUNDINGS ARE HINTING AT THIS PROBABILITY AND WILL CONTINUE TO MONITOR THE SITUATION FOR A POSSIBLE DENSE FOG ADVISORY MONDAY NIGHT INTO TUESDAY MORNING. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 230 AM MONDAY... TUESDAY: ON TUESDAY THE SURFACE HIGH CONTINUES TO MOVE SOUTHEASTWARD OFF THE SOUTH CAROLINA COAST. WITH A LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT APPROACHING FROM THE WEST...CENTRAL NORTH CAROLINA WILL BE IN THE MIDDLE OF A WARM AIR ADVECTION REGIME WHICH WILL INCREASE IN STRENGTH AS THE DAY GOES ON. EXPECT TEMPERATURES DRAMATICALLY HIGHER ON TUESDAY WITH MID 60S NORTHWEST TO NEAR 70 IN THE SOUTHEAST. EXPECT SOME THINNING OF CLOUDS IN THE AFTERNOON BUT OVERALL SHOULD REMAIN PARTLY TO MOSTLY CLOUDY IF NOT OVERCAST. DESPITE THE CLOUDS CENTRAL NC SHOULD REMAIN DRY ON TUESDAY.-ELLIS TUESDAY NIGHT: THE MSLP GRADIENT TIGHTENS TUESDAY NIGHT OVER NC WITH THE GROWING CONTRAST BETWEEN THE OFFSHORE HIGH AND INCOMING COLD FRONT. LOW LEVEL WARM AIR ADVECTION AND CLOUDS WILL TRANSLATE INTO MILD PREFRONTAL LOWS... AND HAVE RAISED THEM SEVERAL DEGREES TO 54-61. EXPECT PATCHY LIGHT SHOWERS TO DEVELOP OVERNIGHT MAINLY IN THE WEST WITH INCREASING PRECIP WATER TO OVER 1 INCH AND DEEPENING MOIST UPGLIDE. FOR WEDNESDAY/WEDNESDAY NIGHT: WINDY/WET/WARM FOLLOWED BY A STARK COOLDOWN. THE RECENT NAM RUNS HAVE TRENDED MUCH FASTER WITH THE INCOMING FRONT AND ASSOCIATED WARM-CONVEYOR BAND OF SHOWERS... WHILE THE MORE CONSISTENT GFS HAS SHOWN JUST A SLIGHT SLOWING TREND AND AGREES WITH THE ECMWF TIMING. CONSENSUS OF THE GFS/ECMWF BRINGS IN JUST LIGHT SCATTERED SHOWERS THROUGH WEDNESDAY MORNING... WITH THE MORE NUMEROUS AND HEAVIER SHOWERS ARRIVING IN THE AFTERNOON THROUGH EVENING SWEEPING WEST TO EAST. PRECIP WATER VALUES ARE EXPECTED TO EXCEED 1.5 INCHES... HIGHLY ANOMALOUS FOR LATE JANUARY (IN THE 99TH PERCENTILE)... AND FORECAST SOUNDINGS DEPICT A DEEP WARM LAYER (LCL TO FREEZING OF 3.0-3.2 KM)... THUS HEAVY DOWNPOURS ARE POSSIBLE. HAVE RAISED POPS TO CATEGORICAL... FOCUSING AFTER 18Z IN THE PIEDMONT/WRN SANDHILLS AND AFTER 23Z IN THE ERN SANDHILLS AND COASTAL PLAIN. THE VERTICAL PROFILE BECOMES NEARLY MOIST ADIABATIC AT BEST... AND WITH THE MARGINAL LAPSE RATES AND LACK OF INSTABILITY IN THE MIXED PHASE REGION ALOFT... WILL NOT INCLUDE THUNDER AT THIS TIME DUE TO ITS EXPECTED SPARSITY BUT THIS MAY NEED TO BE ADDED TO LATER FORECASTS. DESPITE THE LACK OF DOWNWARD MOMENTUM THE BOUNDARY LAYER WINDS ALONE FAVOR QUITE A WINDY DAY... SUSTAINED 15-20 MPH GUSTING TO AROUND 30 MPH... AND WOULD NOT BE AT ALL SURPRISED TO SEE THESE NUMBERS COME UP A BIT IN LATER FORECASTS TOO... ONCE WE CAN OBSERVE UPSTREAM PREFRONTAL CONDITIONS. EVEN WITH THE MODERATE TO HEAVY SHOWERS... WE SHOULD SEE STORM TOTAL QPF AMOUNTS OF A THIRD TO HALF INCH... LIMITED BY THE SPEED OF THIS SYSTEM. HIGHS FROM 64 NW TO 76 SE. LOWS 36-46 WITH THE FRONT SHIFTING OFF THE COAST AFTER MIDNIGHT... AND SKIES CLEARING LATE. -GIH && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 225 PM SUNDAY... FOR THURSDAY THROUGH FRIDAY: THE DAMPENING LONGWAVE TROUGH AXIS WILL BE HEADING EASTWARD OFF THE COAST THURSDAY MORNING... ALTHOUGH EYES THEN TURN TO A STRONG MID LEVEL SHORTWAVE TROUGH DROPPING SOUTHWARD INTO THE UPPER MIDWEST EARLY THURSDAY... POISED TO SWING THROUGH THE MIDATLANTIC REGION ON FRIDAY. LOW LEVEL THICKNESSES PLUNGE FROM LATE WEDNESDAY INTO THURSDAY MORNING... FROM 55-60 METERS ABOVE NORMAL DOWN TO NEAR OR JUST UNDER NORMAL AS MODIFIED HIGH PRESSURE BUILDS EASTWARD OVER THE GULF COAST. WE SHOULD STAY A LITTLE BREEZY THROUGH EARLY THURSDAY. HIGHS 44-55 WITH MOSTLY SUNNY SKIES. EXPECT INCREASING MID AND HIGH CLOUDS THURSDAY NIGHT AS THE ALREADY-SWIFT UPPER LEVEL FLOW STRENGTHENS ANEW TO 140+ KTS IN RESPONSE TO THE APPROACHING ENERGY ALOFT. LOWS IN THE LOWER 30S. AS ONE MIGHT EXPECT AT THIS RANGE... THE GFS/ECMWF DIFFER A BIT WITH REGARDS TO TIMING AND STRENGTH OF THE VORTICITY MAXIMUM THAT CROSSES THE AREA FRIDAY... BUT THIS PATTERN WITH DECENT DYNAMIC FORCING... COLD AIR IN PLACE... AND BACKING LOW LEVEL WINDS ALLOWING A TRANSPORT OF MOISTURE... DOES SUPPORT AT LEAST A SMALL CHANCE OF A QUICK SNOW SHOWER... AND IF THE ECMWF`S STRONGER WAVE IS CORRECT... SCATTERED COVERAGE COULD BE ACHIEVED. WILL PLACE A SLIGHT CHANCE OF A SNOW SHOWER ALONG/NORTH OF HIGHWAY 64. WITH THICKNESSES FRIDAY RUNNING 20 METER BELOW NORMAL AND SCATTERED TO BROKEN COLD AIR CONVECTIVE CLOUDS... EXPECT HIGHS OF JUST 36-40 IN THE NORTH AND 40-46 SOUTHEAST. FOR FRIDAY NIGHT THROUGH SUNDAY: AS A YUKON-SOURCE HIGH BUILDS OVERHEAD FROM THE NNW WITH THE POLAR WESTERLIES EXTENDING WELL DOWN TO OUR LATITUDE... EXPECT FAIR TO PARTLY CLOUDY SKIES AND CHILLY TEMPS FRIDAY NIGHT INTO SATURDAY. ANOTHER MID LEVEL WAVE SWINGING THROUGH THE MIDATLANTIC AND NORTHEAST SATURDAY AFTERNOON/NIGHT WILL BRING ANOTHER CLIPPER FRONT THROUGH THE REGION... REINFORCING THE BELOW-NORMAL TEMPS. NO POPS FOR THIS TIME FRAME YET BUT ANOTHER ROUND OF ISOLATED SNOW SHOWERS FOR THE NORTHERN BORDER COUNTIES IS CERTAINLY POSSIBLE EARLY SUNDAY. LOWS IN THE 20S AND HIGHS IN THE LOW-MID 40S. -GIH && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 1220 AM MONDAY... 24 HOUR TAF PERIOD: TRICKY FORECAST OVERNIGHT TONIGHT AS RADAR CURRENTLY SHOWING LIGHT PRECIPITATION MOVING ACROSS THE FOOTHILLS AND INTO THE WESTERN PIEDMONT OF NORTH CAROLINA. THIS COMBINED WITH SUB FREEZING TEMPERATURES COULD GIVE A CHANCE FOR SOME LIGHT FREEZING RAIN FROM WEST TO EAST ACROSS THE AREA. WHILE THERE IS A CHANCE THAT KINT AND KGSO COULD GET SOME LIGHT RAIN BETWEEN 6 AND 8Z...CLOUD COVER HAS KEPT TEMPERATURES IN THE MID 30S. IN ADDITION THE HEAVIER RETURNS ON THE RADAR HAVE BEGUN TO MOVE SOUTH OF KINT AND KGSO AND THEREFORE ONLY A THIN BAND OF PRECIPITATION ORIENTED NORTH TO SOUTH WILL CROSS THE AREA...MOST LIKELY WITH TEMPERATURES ABOVE FREEZING. FURTHER EAST WHERE THERE IS LESS CLOUD COVER TEMPERATURES HAVE ALREADY DIPPED TOWARDS THE FREEZING MARK WITH KRDU AND KFAY ON THE VERGE OF FREEZING AND KRWI ALREADY REPORTING 26 DEGREES. WITH RETURNS MOVING TO THE SOUTH...THERE IS A GROWING CHANCE OF SOME FREEZING RAIN AT KFAY...BUT THE ONSET OF OVERCAST SKIES HAS ELEVATED THE TEMPERATURE IN THE LAST COUPLE OF HOURS. SAME IS TRUE FOR KRDU. WILL COVER ALL FREEZING RAIN WITH TEMPO GROUPS IN THE TAF AND HAVE LEFT IT OUT OF KRWI AT THIS TIME BECAUSE OF WEAKENING RADAR TRENDS. OTHERWISE EXPECT LIGHT SOUTHWESTERLY FLOW WITH CEILING GRADUALLY COMING DOWN THROUGHOUT THE TAF PERIOD WITH MVFR AND IFR CEILINGS LIKELY BY EARLY TUESDAY MORNING. LOOKING AHEAD: FOG AND OR LOW STRATUS WILL BE LIKELY TUESDAY MORNING. ADVERSE CONDITIONS ARE ALSO LIKELY WEDNESDAY INTO THURSDAY WITH THE PASSAGE OF A FRONTAL SYSTEM. ON FRIDAY...NORTHERN SITES MAY HAVE A CHANCE FOR SOME LIGHT SNOW SHOWERS. && .RAH WATCHES/WARNINGS/ADVISORIES... FREEZING RAIN ADVISORY FROM 9 PM THIS EVENING TO 9 AM EST MONDAY FOR NCZ007>010-021>026-038>041. && $$ SYNOPSIS...MWS NEAR TERM...ELLIS SHORT TERM...ELLIS/HARTFIELD LONG TERM...HARTFIELD AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1223 AM EST MON JAN 28 2013 .SYNOPSIS... AN UPPER LEVEL DISTURBANCE WILL CROSS THE REGION TONIGHT THROUGH MONDAY MORNING. DEVELOPING SOUTH TO SOUTHWEST FLOW WILL BRING WARMER TEMPERATURES TO CENTRAL NORTH CAROLINA TUESDAY AND WEDNESDAY WITH A SHOWERS LIKELY AHEAD OF A STRONG COLD FRONT WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT. && .NEAR TERM /TONIGHT THROUGH MONDAY/... AS OF 930 PM SUNDAY... NO CHANGE TO THE FREEZING RAIN ADVISORY TONIGHT. LIGHT PRECIP ON THE EASTERN FRINGES OF A WARM FRONT MOVING INTO THE OH VALLEY IS NOW MOVING INTO NORTHEAST TN....THOUGH WITH A LIMITED NUMBER OF SITES REPORTING MEASURABLE PRECIP. THE 00Z KGSO RAOB CAME IN PRETTY MUCH IN TUNE WITH FORECAST SOUNDINGS...SHOWING A SIGNIFICANT DRY LAYER BETWEEN 850MB AND 600MB...COINCIDENT WITH THE LOW/MID LEVEL RIDGE AXIS OVER THE SOUTHEAST US. THE HRRR 1KM REFLECTIVITY FORECAST CONTINUES TO EXPAND PRECIP SOUTHEAST INTO THE PIEDMONT AND NORTHERN COASTAL PLAIN TONIGHT BETWEEN 1AM AND 8AM. HOWEVER...RAP SOUNDINGS NEVER QUITE SHOW SATURATION BELOW 1KM...SO IT REMAINS QUESTIONABLE WEATHER THERE WILL BE ENOUGH ISENTROPIC LIFT AND MOISTURE TO SUFFICIENTLY OVERCOME THE DRY AIR BELOW 10K FT. THUS..UNCERTAINTY IN THE FORECAST IS BASED AROUND MOISTURE AND PRECIP. TEMPERATURES HAVE DROPPED RAPIDLY BELOW FREEZING IN AREAS EAST OF US HWY 1 WHERE MID LEVEL CLOUD COVER HAS YET TO MOVE IN. WEST OF US HWY 1...TEMPS ARE HOLDING IN THE MID TO UPPER 30S...AND THERE IS THE POTENTIAL THEY THEY MAY ONLY FALL TO AT OR JUST ABOVE FREEZING WITH SURFACE WETBULB TEMPS ALREADY ESSENTIALLY AT 30 OR ABOVE. BASED ON THIS...CONFIDENCE IN FREEZING RAIN IS HIGHEST NORTH OF THE TRIANGLE INTO THE NORTHERN COASTAL PLAIN...GENERALLY FROM CHAPEL HILL/DURHAM TO LOUISBURG...WARRENTON AND POTENTIALLY AS FAR EAST AS ROANOKE RAPIDS. HALIFAX COUNTY IS NOT CURRENTLY IN THE ADVISORY AND BASED ON COORDINATION OF NEIGHBORING OFFICES...WILL HOLD OFF ON ADDING TO THE ADVISORY UNTIL WE GET A BETTER SENSE OF HOW THE PRECIP IS EVOLVING. WE STILL EXPECT THE RAIN/FREEZING RAIN TO BE PATCHY AND LIGHT...JUST A TRACE TO A FEW HUNDREDTHS IN MOST LOCATIONS. -SMITH MONDAY...FIRST AREA OF PRECIP EXITS THE NORTHERN SECTIONS EARLY IN THE MORNING. INCREASING LOW LEVEL SLY WILL MAINTAIN LOW CLOUDS THROUGH THE DAY WITH SPOTS OF DRIZZLE OR LIGHT RAIN POSSIBLE. STILL CHILLY WITH TEMPS IN THE 40S FAR NORTH TO THE LOW AND POSSIBLY MID 50S FAR SOUTH-SOUTHEAST. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... AS OF 110 PM SUNDAY... FOR MONDAY NIGHT: THE LOW LEVEL FLOW SHOULD VEER A BIT SO AS TO GREATLY DIMINISH THE LOW LEVEL MOIST UPGLIDE... BUT THE COMBINATION OF EARLY-NIGHT GROUND COOLING RESULTING IN LOW LEVEL STABILIZATION (REINFORCED BY STRENGTHENING WARM AIR ADVECTION AT 950-850 MB) AND MOISTENING SHOULD RESULT IN WIDESPREAD THICK STRATUS AND FOG WITHIN THE RESIDUAL STABLE POOL OVER ALL OF CENTRAL NC STARTING IN THE EARLY EVENING... ALONG WITH PATCHES OF VERY LIGHT DRIZZLE IN THE NRN PIEDMONT BENEATH THE TAIL OF THE EXITING LOW LEVEL JET. WITH A SLOWLY MODIFYING AIR MASS AND CLOUDS BLANKETING THE AREA... EXPECT LOWS TO BE MINIMALLY LOWER THAN MONDAY HIGHS... 40-47. FOR TUESDAY/TUESDAY NIGHT: THE RELATIVE CALM BEFORE THE STORM. THE OFFSHORE PARENT SURFACE HIGH WILL NOSE WESTWARD THROUGH THE SOUTHEAST AND CAROLINAS WHILE HEIGHTS STEADILY RISE ALONG THE EASTERN SEABOARD IN RESPONSE TO THE APPROACH LONGWAVE TROUGH. LOW LEVEL MOISTURE REMAINS ABUNDANT HOWEVER ESPECIALLY IN WRN NC THROUGH THE WRN PIEDMONT... AND FORECAST SOUNDINGS INDICATE THAT THE LOW LEVEL STABLE LAYER WILL BE TOUGH TO DISLODGE VIA TRADITIONAL EROSION MECHANISMS SUCH AS VERTICAL MIXING... EDGE DISSOLUTION AND HORIZONTAL DISPERSION... AND THIS IS REFLECTED WELL IN CURRENT FORECAST HIGHS WHICH SUGGEST SUPPRESSED WARMTH OVER THE PIEDMONT. WILL NOT DEPART FAR FROM THIS EARLIER FORECAST... WITH HIGHS RANGING FROM 60 NW TO 76 SE UNDER PARTLY TO MOSTLY CLOUDY SKIES. THIS IS STILL 10-20 DEGREES ABOVE NORMAL ACROSS THE AREA. THE MSLP GRADIENT TIGHTENS TUESDAY NIGHT OVER NC WITH THE GROWING CONTRAST BETWEEN THE OFFSHORE HIGH AND INCOMING COLD FRONT. LOW LEVEL WARM AIR ADVECTION AND CLOUDS WILL TRANSLATE INTO MILD PREFRONTAL LOWS... AND HAVE RAISED THEM SEVERAL DEGREES TO 54-61. EXPECT PATCHY LIGHT SHOWERS TO DEVELOP OVERNIGHT MAINLY IN THE WEST WITH INCREASING PRECIP WATER TO OVER 1 INCH AND DEEPENING MOIST UPGLIDE. FOR WEDNESDAY/WEDNESDAY NIGHT: WINDY/WET/WARM FOLLOWED BY A STARK COOLDOWN. THE RECENT NAM RUNS HAVE TRENDED MUCH FASTER WITH THE INCOMING FRONT AND ASSOCIATED WARM-CONVEYOR BAND OF SHOWERS... WHILE THE MORE CONSISTENT GFS HAS SHOWN JUST A SLIGHT SLOWING TREND AND AGREES WITH THE ECMWF TIMING. CONSENSUS OF THE GFS/ECMWF BRINGS IN JUST LIGHT SCATTERED SHOWERS THROUGH WEDNESDAY MORNING... WITH THE MORE NUMEROUS AND HEAVIER SHOWERS ARRIVING IN THE AFTERNOON THROUGH EVENING SWEEPING WEST TO EAST. PRECIP WATER VALUES ARE EXPECTED TO EXCEED 1.5 INCHES... HIGHLY ANOMALOUS FOR LATE JANUARY (IN THE 99TH PERCENTILE)... AND FORECAST SOUNDINGS DEPICT A DEEP WARM LAYER (LCL TO FREEZING OF 3.0-3.2 KM)... THUS HEAVY DOWNPOURS ARE POSSIBLE. HAVE RAISED POPS TO CATEGORICAL... FOCUSING AFTER 18Z IN THE PIEDMONT/WRN SANDHILLS AND AFTER 23Z IN THE ERN SANDHILLS AND COASTAL PLAIN. THE VERTICAL PROFILE BECOMES NEARLY MOIST ADIABATIC AT BEST... AND WITH THE MARGINAL LAPSE RATES AND LACK OF INSTABILITY IN THE MIXED PHASE REGION ALOFT... WILL NOT INCLUDE THUNDER AT THIS TIME DUE TO ITS EXPECTED SPARSITY BUT THIS MAY NEED TO BE ADDED TO LATER FORECASTS. DESPITE THE LACK OF DOWNWARD MOMENTUM THE BOUNDARY LAYER WINDS ALONE FAVOR QUITE A WINDY DAY... SUSTAINED 15-20 MPH GUSTING TO AROUND 30 MPH... AND WOULD NOT BE AT ALL SURPRISED TO SEE THESE NUMBERS COME UP A BIT IN LATER FORECASTS TOO... ONCE WE CAN OBSERVE UPSTREAM PREFRONTAL CONDITIONS. EVEN WITH THE MODERATE TO HEAVY SHOWERS... WE SHOULD SEE STORM TOTAL QPF AMOUNTS OF A THIRD TO HALF INCH... LIMITED BY THE SPEED OF THIS SYSTEM. HIGHS FROM 64 NW TO 76 SE. LOWS 36-46 WITH THE FRONT SHIFTING OFF THE COAST AFTER MIDNIGHT... AND SKIES CLEARING LATE. -GIH && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 225 PM SUNDAY... FOR THURSDAY THROUGH FRIDAY: THE DAMPENING LONGWAVE TROUGH AXIS WILL BE HEADING EASTWARD OFF THE COAST THURSDAY MORNING... ALTHOUGH EYES THEN TURN TO A STRONG MID LEVEL SHORTWAVE TROUGH DROPPING SOUTHWARD INTO THE UPPER MIDWEST EARLY THURSDAY... POISED TO SWING THROUGH THE MIDATLANTIC REGION ON FRIDAY. LOW LEVEL THICKNESSES PLUNGE FROM LATE WEDNESDAY INTO THURSDAY MORNING... FROM 55-60 METERS ABOVE NORMAL DOWN TO NEAR OR JUST UNDER NORMAL AS MODIFIED HIGH PRESSURE BUILDS EASTWARD OVER THE GULF COAST. WE SHOULD STAY A LITTLE BREEZY THROUGH EARLY THURSDAY. HIGHS 44-55 WITH MOSTLY SUNNY SKIES. EXPECT INCREASING MID AND HIGH CLOUDS THURSDAY NIGHT AS THE ALREADY-SWIFT UPPER LEVEL FLOW STRENGTHENS ANEW TO 140+ KTS IN RESPONSE TO THE APPROACHING ENERGY ALOFT. LOWS IN THE LOWER 30S. AS ONE MIGHT EXPECT AT THIS RANGE... THE GFS/ECMWF DIFFER A BIT WITH REGARDS TO TIMING AND STRENGTH OF THE VORTICITY MAXIMUM THAT CROSSES THE AREA FRIDAY... BUT THIS PATTERN WITH DECENT DYNAMIC FORCING... COLD AIR IN PLACE... AND BACKING LOW LEVEL WINDS ALLOWING A TRANSPORT OF MOISTURE... DOES SUPPORT AT LEAST A SMALL CHANCE OF A QUICK SNOW SHOWER... AND IF THE ECMWF`S STRONGER WAVE IS CORRECT... SCATTERED COVERAGE COULD BE ACHIEVED. WILL PLACE A SLIGHT CHANCE OF A SNOW SHOWER ALONG/NORTH OF HIGHWAY 64. WITH THICKNESSES FRIDAY RUNNING 20 METER BELOW NORMAL AND SCATTERED TO BROKEN COLD AIR CONVECTIVE CLOUDS... EXPECT HIGHS OF JUST 36-40 IN THE NORTH AND 40-46 SOUTHEAST. FOR FRIDAY NIGHT THROUGH SUNDAY: AS A YUKON-SOURCE HIGH BUILDS OVERHEAD FROM THE NNW WITH THE POLAR WESTERLIES EXTENDING WELL DOWN TO OUR LATITUDE... EXPECT FAIR TO PARTLY CLOUDY SKIES AND CHILLY TEMPS FRIDAY NIGHT INTO SATURDAY. ANOTHER MID LEVEL WAVE SWINGING THROUGH THE MIDATLANTIC AND NORTHEAST SATURDAY AFTERNOON/NIGHT WILL BRING ANOTHER CLIPPER FRONT THROUGH THE REGION... REINFORCING THE BELOW-NORMAL TEMPS. NO POPS FOR THIS TIME FRAME YET BUT ANOTHER ROUND OF ISOLATED SNOW SHOWERS FOR THE NORTHERN BORDER COUNTIES IS CERTAINLY POSSIBLE EARLY SUNDAY. LOWS IN THE 20S AND HIGHS IN THE LOW-MID 40S. -GIH && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 1220 AM MONDAY... 24 HOUR TAF PERIOD: TRICKY FORECAST OVERNIGHT TONIGHT AS RADAR CURRENTLY SHOWING LIGHT PRECIPITATION MOVING ACROSS THE FOOTHILLS AND INTO THE WESTERN PIEDMONT OF NORTH CAROLINA. THIS COMBINED WITH SUB FREEZING TEMPERATURES COULD GIVE A CHANCE FOR SOME LIGHT FREEZING RAIN FROM WEST TO EAST ACROSS THE AREA. WHILE THERE IS A CHANCE THAT KINT AND KGSO COULD GET SOME LIGHT RAIN BETWEEN 6 AND 8Z...CLOUD COVER HAS KEPT TEMPERATURES IN THE MID 30S. IN ADDITION THE HEAVIER RETURNS ON THE RADAR HAVE BEGUN TO MOVE SOUTH OF KINT AND KGSO AND THEREFORE ONLY A THIN BAND OF PRECIPITATION ORIENTED NORTH TO SOUTH WILL CROSS THE AREA...MOST LIKELY WITH TEMPERATURES ABOVE FREEZING. FURTHER EAST WHERE THERE IS LESS CLOUD COVER TEMPERATURES HAVE ALREADY DIPPED TOWARDS THE FREEZING MARK WITH KRDU AND KFAY ON THE VERGE OF FREEZING AND KRWI ALREADY REPORTING 26 DEGREES. WITH RETURNS MOVING TO THE SOUTH...THERE IS A GROWING CHANCE OF SOME FREEZING RAIN AT KFAY...BUT THE ONSET OF OVERCAST SKIES HAS ELEVATED THE TEMPERATURE IN THE LAST COUPLE OF HOURS. SAME IS TRUE FOR KRDU. WILL COVER ALL FREEZING RAIN WITH TEMPO GROUPS IN THE TAF AND HAVE LEFT IT OUT OF KRWI AT THIS TIME BECAUSE OF WEAKENING RADAR TRENDS. OTHERWISE EXPECT LIGHT SOUTHWESTERLY FLOW WITH CEILING GRADUALLY COMING DOWN THROUGHOUT THE TAF PERIOD WITH MVFR AND IFR CEILINGS LIKELY BY EARLY TUESDAY MORNING. LOOKING AHEAD: FOG AND OR LOW STRATUS WILL BE LIKELY TUESDAY MORNING. ADVERSE CONDITIONS ARE ALSO LIKELY WEDNESDAY INTO THURSDAY WITH THE PASSAGE OF A FRONTAL SYSTEM. ON FRIDAY...NORTHERN SITES MAY HAVE A CHANCE FOR SOME LIGHT SNOW SHOWERS. && .RAH WATCHES/WARNINGS/ADVISORIES... FREEZING RAIN ADVISORY FROM 9 PM THIS EVENING TO 9 AM EST MONDAY FOR NCZ007>010-021>026-038>041. && $$ SYNOPSIS...WSS NEAR TERM...WSS/SMITH SHORT TERM...HARTFIELD LONG TERM...HARTFIELD AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS RALEIGH NC12
1223 PM EST MON JAN 28 2013 .SYNOPSIS... AN UPPER LEVEL DISTURBANCE WILL CROSS THE REGION TONIGHT THROUGH MONDAY MORNING. DEVELOPING SOUTH TO SOUTHWEST FLOW WILL BRING WARMER TEMPERATURES TO CENTRAL NORTH CAROLINA TUESDAY AND WEDNESDAY WITH A SHOWERS LIKELY AHEAD OF A STRONG COLD FRONT WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT. && .NEAR TERM /TONIGHT THROUGH MONDAY/... AS OF 930 PM SUNDAY... NO CHANGE TO THE FREEZING RAIN ADVISORY TONIGHT. LIGHT PRECIP ON THE EASTERN FRINGES OF A WARM FRONT MOVING INTO THE OH VALLEY IS NOW MOVING INTO NORTHEAST TN....THOUGH WITH A LIMITED NUMBER OF SITES REPORTING MEASURABLE PRECIP. THE 00Z KGSO RAOB CAME IN PRETTY MUCH IN TUNE WITH FORECAST SOUNDINGS...SHOWING A SIGNIFICANT DRY LAYER BETWEEN 850MB AND 600MB...COINCIDENT WITH THE LOW/MID LEVEL RIDGE AXIS OVER THE SOUTHEAST US. THE HRRR 1KM REFLECTIVITY FORECAST CONTINUES TO EXPAND PRECIP SOUTHEAST INTO THE PIEDMONT AND NORTHERN COASTAL PLAIN TONIGHT BETWEEN 1AM AND 8AM. HOWEVER...RAP SOUNDINGS NEVER QUITE SHOW SATURATION BELOW 1KM...SO IT REMAINS QUESTIONABLE WEATHER THERE WILL BE ENOUGH ISENTROPIC LIFT AND MOISTURE TO SUFFICIENTLY OVERCOME THE DRY AIR BELOW 10K FT. THUS..UNCERTAINTY IN THE FORECAST IS BASED AROUND MOISTURE AND PRECIP. TEMPERATURES HAVE DROPPED RAPIDLY BELOW FREEZING IN AREAS EAST OF US HWY 1 WHERE MID LEVEL CLOUD COVER HAS YET TO MOVE IN. WEST OF US HWY 1...TEMPS ARE HOLDING IN THE MID TO UPPER 30S...AND THERE IS THE POTENTIAL THEY THEY MAY ONLY FALL TO AT OR JUST ABOVE FREEZING WITH SURFACE WETBULB TEMPS ALREADY ESSENTIALLY AT 30 OR ABOVE. BASED ON THIS...CONFIDENCE IN FREEZING RAIN IS HIGHEST NORTH OF THE TRIANGLE INTO THE NORTHERN COASTAL PLAIN...GENERALLY FROM CHAPEL HILL/DURHAM TO LOUISBURG...WARRENTON AND POTENTIALLY AS FAR EAST AS ROANOKE RAPIDS. HALIFAX COUNTY IS NOT CURRENTLY IN THE ADVISORY AND BASED ON COORDINATION OF NEIGHBORING OFFICES...WILL HOLD OFF ON ADDING TO THE ADVISORY UNTIL WE GET A BETTER SENSE OF HOW THE PRECIP IS EVOLVING. WE STILL EXPECT THE RAIN/FREEZING RAIN TO BE PATCHY AND LIGHT...JUST A TRACE TO A FEW HUNDREDTHS IN MOST LOCATIONS. -SMITH MONDAY...FIRST AREA OF PRECIP EXITS THE NORTHERN SECTIONS EARLY IN THE MORNING. INCREASING LOW LEVEL SLY WILL MAINTAIN LOW CLOUDS THROUGH THE DAY WITH SPOTS OF DRIZZLE OR LIGHT RAIN POSSIBLE. STILL CHILLY WITH TEMPS IN THE 40S FAR NORTH TO THE LOW AND POSSIBLY MID 50S FAR SOUTH-SOUTHEAST. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... AS OF 110 PM SUNDAY... FOR MONDAY NIGHT: THE LOW LEVEL FLOW SHOULD VEER A BIT SO AS TO GREATLY DIMINISH THE LOW LEVEL MOIST UPGLIDE... BUT THE COMBINATION OF EARLY-NIGHT GROUND COOLING RESULTING IN LOW LEVEL STABILIZATION (REINFORCED BY STRENGTHENING WARM AIR ADVECTION AT 950-850 MB) AND MOISTENING SHOULD RESULT IN WIDESPREAD THICK STRATUS AND FOG WITHIN THE RESIDUAL STABLE POOL OVER ALL OF CENTRAL NC STARTING IN THE EARLY EVENING... ALONG WITH PATCHES OF VERY LIGHT DRIZZLE IN THE NRN PIEDMONT BENEATH THE TAIL OF THE EXITING LOW LEVEL JET. WITH A SLOWLY MODIFYING AIR MASS AND CLOUDS BLANKETING THE AREA... EXPECT LOWS TO BE MINIMALLY LOWER THAN MONDAY HIGHS... 40-47. FOR TUESDAY/TUESDAY NIGHT: THE RELATIVE CALM BEFORE THE STORM. THE OFFSHORE PARENT SURFACE HIGH WILL NOSE WESTWARD THROUGH THE SOUTHEAST AND CAROLINAS WHILE HEIGHTS STEADILY RISE ALONG THE EASTERN SEABOARD IN RESPONSE TO THE APPROACH LONGWAVE TROUGH. LOW LEVEL MOISTURE REMAINS ABUNDANT HOWEVER ESPECIALLY IN WRN NC THROUGH THE WRN PIEDMONT... AND FORECAST SOUNDINGS INDICATE THAT THE LOW LEVEL STABLE LAYER WILL BE TOUGH TO DISLODGE VIA TRADITIONAL EROSION MECHANISMS SUCH AS VERTICAL MIXING... EDGE DISSOLUTION AND HORIZONTAL DISPERSION... AND THIS IS REFLECTED WELL IN CURRENT FORECAST HIGHS WHICH SUGGEST SUPPRESSED WARMTH OVER THE PIEDMONT. WILL NOT DEPART FAR FROM THIS EARLIER FORECAST... WITH HIGHS RANGING FROM 60 NW TO 76 SE UNDER PARTLY TO MOSTLY CLOUDY SKIES. THIS IS STILL 10-20 DEGREES ABOVE NORMAL ACROSS THE AREA. THE MSLP GRADIENT TIGHTENS TUESDAY NIGHT OVER NC WITH THE GROWING CONTRAST BETWEEN THE OFFSHORE HIGH AND INCOMING COLD FRONT. LOW LEVEL WARM AIR ADVECTION AND CLOUDS WILL TRANSLATE INTO MILD PREFRONTAL LOWS... AND HAVE RAISED THEM SEVERAL DEGREES TO 54-61. EXPECT PATCHY LIGHT SHOWERS TO DEVELOP OVERNIGHT MAINLY IN THE WEST WITH INCREASING PRECIP WATER TO OVER 1 INCH AND DEEPENING MOIST UPGLIDE. FOR WEDNESDAY/WEDNESDAY NIGHT: WINDY/WET/WARM FOLLOWED BY A STARK COOLDOWN. THE RECENT NAM RUNS HAVE TRENDED MUCH FASTER WITH THE INCOMING FRONT AND ASSOCIATED WARM-CONVEYOR BAND OF SHOWERS... WHILE THE MORE CONSISTENT GFS HAS SHOWN JUST A SLIGHT SLOWING TREND AND AGREES WITH THE ECMWF TIMING. CONSENSUS OF THE GFS/ECMWF BRINGS IN JUST LIGHT SCATTERED SHOWERS THROUGH WEDNESDAY MORNING... WITH THE MORE NUMEROUS AND HEAVIER SHOWERS ARRIVING IN THE AFTERNOON THROUGH EVENING SWEEPING WEST TO EAST. PRECIP WATER VALUES ARE EXPECTED TO EXCEED 1.5 INCHES... HIGHLY ANOMALOUS FOR LATE JANUARY (IN THE 99TH PERCENTILE)... AND FORECAST SOUNDINGS DEPICT A DEEP WARM LAYER (LCL TO FREEZING OF 3.0-3.2 KM)... THUS HEAVY DOWNPOURS ARE POSSIBLE. HAVE RAISED POPS TO CATEGORICAL... FOCUSING AFTER 18Z IN THE PIEDMONT/WRN SANDHILLS AND AFTER 23Z IN THE ERN SANDHILLS AND COASTAL PLAIN. THE VERTICAL PROFILE BECOMES NEARLY MOIST ADIABATIC AT BEST... AND WITH THE MARGINAL LAPSE RATES AND LACK OF INSTABILITY IN THE MIXED PHASE REGION ALOFT... WILL NOT INCLUDE THUNDER AT THIS TIME DUE TO ITS EXPECTED SPARSITY BUT THIS MAY NEED TO BE ADDED TO LATER FORECASTS. DESPITE THE LACK OF DOWNWARD MOMENTUM THE BOUNDARY LAYER WINDS ALONE FAVOR QUITE A WINDY DAY... SUSTAINED 15-20 MPH GUSTING TO AROUND 30 MPH... AND WOULD NOT BE AT ALL SURPRISED TO SEE THESE NUMBERS COME UP A BIT IN LATER FORECASTS TOO... ONCE WE CAN OBSERVE UPSTREAM PREFRONTAL CONDITIONS. EVEN WITH THE MODERATE TO HEAVY SHOWERS... WE SHOULD SEE STORM TOTAL QPF AMOUNTS OF A THIRD TO HALF INCH... LIMITED BY THE SPEED OF THIS SYSTEM. HIGHS FROM 64 NW TO 76 SE. LOWS 36-46 WITH THE FRONT SHIFTING OFF THE COAST AFTER MIDNIGHT... AND SKIES CLEARING LATE. -GIH && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 225 PM SUNDAY... FOR THURSDAY THROUGH FRIDAY: THE DAMPENING LONGWAVE TROUGH AXIS WILL BE HEADING EASTWARD OFF THE COAST THURSDAY MORNING... ALTHOUGH EYES THEN TURN TO A STRONG MID LEVEL SHORTWAVE TROUGH DROPPING SOUTHWARD INTO THE UPPER MIDWEST EARLY THURSDAY... POISED TO SWING THROUGH THE MIDATLANTIC REGION ON FRIDAY. LOW LEVEL THICKNESSES PLUNGE FROM LATE WEDNESDAY INTO THURSDAY MORNING... FROM 55-60 METERS ABOVE NORMAL DOWN TO NEAR OR JUST UNDER NORMAL AS MODIFIED HIGH PRESSURE BUILDS EASTWARD OVER THE GULF COAST. WE SHOULD STAY A LITTLE BREEZY THROUGH EARLY THURSDAY. HIGHS 44-55 WITH MOSTLY SUNNY SKIES. EXPECT INCREASING MID AND HIGH CLOUDS THURSDAY NIGHT AS THE ALREADY-SWIFT UPPER LEVEL FLOW STRENGTHENS ANEW TO 140+ KTS IN RESPONSE TO THE APPROACHING ENERGY ALOFT. LOWS IN THE LOWER 30S. AS ONE MIGHT EXPECT AT THIS RANGE... THE GFS/ECMWF DIFFER A BIT WITH REGARDS TO TIMING AND STRENGTH OF THE VORTICITY MAXIMUM THAT CROSSES THE AREA FRIDAY... BUT THIS PATTERN WITH DECENT DYNAMIC FORCING... COLD AIR IN PLACE... AND BACKING LOW LEVEL WINDS ALLOWING A TRANSPORT OF MOISTURE... DOES SUPPORT AT LEAST A SMALL CHANCE OF A QUICK SNOW SHOWER... AND IF THE ECMWF`S STRONGER WAVE IS CORRECT... SCATTERED COVERAGE COULD BE ACHIEVED. WILL PLACE A SLIGHT CHANCE OF A SNOW SHOWER ALONG/NORTH OF HIGHWAY 64. WITH THICKNESSES FRIDAY RUNNING 20 METER BELOW NORMAL AND SCATTERED TO BROKEN COLD AIR CONVECTIVE CLOUDS... EXPECT HIGHS OF JUST 36-40 IN THE NORTH AND 40-46 SOUTHEAST. FOR FRIDAY NIGHT THROUGH SUNDAY: AS A YUKON-SOURCE HIGH BUILDS OVERHEAD FROM THE NNW WITH THE POLAR WESTERLIES EXTENDING WELL DOWN TO OUR LATITUDE... EXPECT FAIR TO PARTLY CLOUDY SKIES AND CHILLY TEMPS FRIDAY NIGHT INTO SATURDAY. ANOTHER MID LEVEL WAVE SWINGING THROUGH THE MIDATLANTIC AND NORTHEAST SATURDAY AFTERNOON/NIGHT WILL BRING ANOTHER CLIPPER FRONT THROUGH THE REGION... REINFORCING THE BELOW-NORMAL TEMPS. NO POPS FOR THIS TIME FRAME YET BUT ANOTHER ROUND OF ISOLATED SNOW SHOWERS FOR THE NORTHERN BORDER COUNTIES IS CERTAINLY POSSIBLE EARLY SUNDAY. LOWS IN THE 20S AND HIGHS IN THE LOW-MID 40S. -GIH && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 1220 AM MONDAY... 24 HOUR TAF PERIOD: TRICKY FORECAST OVERNIGHT TONIGHT AS RADAR CURRENTLY SHOWING LIGHT PRECIPITATION MOVING ACROSS THE FOOTHILLS AND INTO THE WESTERN PIEDMONT OF NORTH CAROLINA. THIS COMBINED WITH SUB FREEZING TEMPERATURES COULD GIVE A CHANCE FOR SOME LIGHT FREEZING RAIN FROM WEST TO EAST ACROSS THE AREA. WHILE THERE IS A CHANCE THAT KINT AND KGSO COULD GET SOME LIGHT RAIN BETWEEN 6 AND 8Z...CLOUD COVER HAS KEPT TEMPERATURES IN THE MID 30S. IN ADDITION THE HEAVIER RETURNS ON THE RADAR HAVE BEGUN TO MOVE SOUTH OF KINT AND KGSO AND THEREFORE ONLY A THIN BAND OF PRECIPITATION ORIENTED NORTH TO SOUTH WILL CROSS THE AREA...MOST LIKELY WITH TEMPERATURES ABOVE FREEZING. FURTHER EAST WHERE THERE IS LESS CLOUD COVER TEMPERATURES HAVE ALREADY DIPPED TOWARDS THE FREEZING MARK WITH KRDU AND KFAY ON THE VERGE OF FREEZING AND KRWI ALREADY REPORTING 26 DEGREES. WITH RETURNS MOVING TO THE SOUTH...THERE IS A GROWING CHANCE OF SOME FREEZING RAIN AT KFAY...BUT THE ONSET OF OVERCAST SKIES HAS ELEVATED THE TEMPERATURE IN THE LAST COUPLE OF HOURS. SAME IS TRUE FOR KRDU. WILL COVER ALL FREEZING RAIN WITH TEMPO GROUPS IN THE TAF AND HAVE LEFT IT OUT OF KRWI AT THIS TIME BECAUSE OF WEAKENING RADAR TRENDS. OTHERWISE EXPECT LIGHT SOUTHWESTERLY FLOW WITH CEILING GRADUALLY COMING DOWN THROUGHOUT THE TAF PERIOD WITH MVFR AND IFR CEILINGS LIKELY BY EARLY TUESDAY MORNING. LOOKING AHEAD: FOG AND OR LOW STRATUS WILL BE LIKELY TUESDAY MORNING. ADVERSE CONDITIONS ARE ALSO LIKELY WEDNESDAY INTO THURSDAY WITH THE PASSAGE OF A FRONTAL SYSTEM. ON FRIDAY...NORTHERN SITES MAY HAVE A CHANCE FOR SOME LIGHT SNOW SHOWERS. && .RAH WATCHES/WARNINGS/ADVISORIES... FREEZING RAIN ADVISORY FROM 9 PM THIS EVENING TO 9 AM EST MONDAY FOR NCZ007>010-021>026-038>041. && $$ SYNOPSIS...WSS NEAR TERM...WSS/SMITH SHORT TERM...HARTFIELD LONG TERM...HARTFIELD AVIATION...ELLIS
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
717 AM CST MON JAN 28 2013 .UPDATE...THE LOW CIGS AND VSBY UNDER 2 MILES HAS MOVED INTO THE THIEF RIVER FALLS AREA. LOCAL REPORTS FROM THAT AREA INDICATE LIGHT FREEZING DRIZZLE STARTED ABOUT AN HOUR AGO. THUS...WILL EXPAND THE FREEZING RAIN ADVISORY INTO THIS AREA. INCOMING RAP GUIDANCE STILL SUGGEST VSBY WILL IMPROVE BY 18Z...WHICH SHOULD CORRESPOND TO THE FREEZING DRIZZLE ENDING. THIS MAKES SENSE CONSIDERING SUBSIDENCE ON THE BACK SIDE OF THE DEPARTING UPPER WAVE. SATELLITE IMAGERY CONFIRMS THIS WITH CLEARING SKY ABOUT TO ENTER THE SOUTHWEST FA. && .AVIATION...EXPECT MVFR/IFR CONDITIONS TO AFFECT AREAS ALONG AND EAST OF THE RED RIVER VALLEY THROUGH THE MORNING HOURS. THE NORTHERN/WESTERN EDGE OF THESE LOW CIGS MIGHT ADVECT EASTWARD THIS AFTERNOON...WITH VFR CONDITIONS POSSIBLY MOVING INTO KGFK/KTVF BY LATE AFTERNOON (ALTHOUGH WILL REMAIN PESSIMISTIC IN THE TAF FORECAST). FREEZING DRIZZLE POSSIBLE THROUGH THE MORNING HOURS...THEN A BAND OF HEAVIER SNOW WILL MOVE INTO WEST CENTRAL MINNESOTA LATER THIS AFTERNOON. WINDS WILL REMAIN LIGHT THROUGH THE PERIOD. && .PREV DISCUSSION... /ISSUED 428 AM CST MON JAN 28 2013/ UPDATE...DID NOT WANT TO COMPLICATE THINGS ANY MORE...BUT GETTING REPORTS OF FREEZING DRIZZLE ACROSS THE SOUTHERN HALF OF THE FORECAST AREA RESULTING IN ICY ROADS. WILL NEED TO ISSUE A FREEZING RAIN ADVISORY (FOR FREEZING DRIZZLE) THROUGH THE MORNING HOURS. SNOW SHOWERS WILL MOVE ACROSS THE NORTHERN PART OF THIS ADVISORY OVER THE NEXT FEW HOURS...WHICH WILL LIKELY END THE FREEZING DRIZZLE HERE. LATEST RAP INDICATES VISIBILITY WILL IMPROVE ACROSS THE SOUTHERN PART OF THIS ADVISORY BY NOON...WHICH SHOULD CORRESPOND TO THE END OF THE FREEZING DRIZZLE. PREV DISCUSSION... /ISSUED 335 AM CST MON JAN 28 2013/ SHORT TERM (TODAY-WED NIGHT)...THE MAIN CONCERN THIS PERIOD WILL BE THE POTENTIAL OF A HEAVY SNOW BAND ACROSS THE SOUTHEAST FA. 00Z MODELS IN DECENT AGREEMENT AND WILL USE A BLEND. A COUPLE SHORTWAVES IN SOUTHWEST FLOW ALOFT WILL AFFECT THE REGION TODAY. THE FIRST SHORTWAVE IS CURRENTLY (09Z) ALONG THE SOUTH DAKOTA/NORTH DAKOTA BORDER...AND WILL CONTINUE TO PROPAGATE NE THROUGH THE DAY. THERE IS AN AREA OF SCATTERED SNOW SHOWERS ASSOCIATED WITH THIS FEATURE...AND WILL INCLUDE 50% POPS ACROSS THE NORTHERN FA THIS MORNING. EXPECT FOG THROUGH THE MORNING HOURS ACROSS THE SOUTHERN FA ASSOCIATED WITH HIGHER SURFACE MOISTURE. THERE HAVE BEEN NO REPORTS OF FREEZING DRIZZLE...AND MOST VISIBILITIES ARE 1/2SM OR GREATER. WILL MONITOR...BUT FOR NOW NO HEADLINES ARE NEEDED THROUGH THE MORNING HOURS. ATTENTION THEN TURNS TO THE NEXT SHORTWAVE THAT WILL EJECT FROM THE WEST COAST TROUGH AND INTO THE NORTHERN PLAINS. THIS FEATURE WILL INDUCE MID-LEVEL FRONTOGENESIS AND LEAD TO A BAND OF PRECIP BY LATE AFTERNOON...CONTINUING INTO THE OVERNIGHT HOURS. MODELS ARE IN GENERAL AGREEMENT WITH THE LOCATION OF THIS BAND...GENERALLY FROM THE EXTREME SOUTHERN RED RIVER VALLEY INTO THE PARK RAPIDS AREA (CONTINUING TO THE NORTHEAST). THE ECMWF/GFS ARE SLIGHTLY NORTH OF THE NAM/RAP WITH PLACEMENT. THE ECMWF/GFS SHOW 0.50-0.70 INCHES QPF WITHIN THE HEAVIEST BAND...WHILE THE NAM/4-KM WRF SHOW 0.80-1.00 INCHES QPF WITHIN THE HEAVIEST BAND. CONDITIONAL INSTABILITY PARAMETERS ARE FAVORABLE...SUGGESTING THAT THE HIGHER RESOLUTION MODELS MAY BE MORE CORRECT (HIGHER QPF). 850MB TEMPS WILL BE ABOVE FREEZING AS THE PRECIP BEGINS...BUT SHOULD QUICKLY COOL TO BELOW FREEZING. A BRIEF PERIOD OF FREEZING RAIN WILL BE POSSIBLE BEFORE CHANGING OVER TO SNOW. SNOW RATIO VALUES WILL BE LOW (MORE TOWARD 10:1-12:1). FINAL SNOW AMOUNTS WILL DEPEND UPON THE DURATION OF THE FREEZING RAIN BEFORE CHANGING TO SNOW. THE OTHER CHALLENGING ASPECT OF THESE EVENTS IS THAT THE HEAVIEST BAND OF SNOW IS QUITE NARROW. THE POTENTIAL EXISTS FOR 6-12 INCHES WITHIN THE HEAVIEST BAND...WITH LIGHTER AMOUNTS ON EITHER SIDE...BUT NOT EXACTLY SURE WHERE THE HEAVIEST BAND WILL BE LOCATED. STILL A FEW QUESTIONS WITH THIS EVENT...AND THE SMART THING TO DO AT THIS POINT WILL BE A WINTER STORM WATCH ACROSS THE AREA WHERE THE HEAVY SNOW IS POSSIBLE. TUESDAY-WEDNESDAY NIGHT...MID-UPPER LEVEL TROUGH WILL PASS THROUGH THE REGION TUESDAY NIGHT WITH A COLD FRONT PASSING THROUGH. WILL NEED TO WATCH WINDS TUE NIGHT AS THE COLD FRONT MOVES THROUGH. THERE SHOULD ALSO BE AN AREA OF SNOW SHOWERS. ABOVE NORMAL TEMPS WILL TRANSITION TO BELOW NORMAL BY WEDNESDAY. LONG TERM (THURSDAY-SUNDAY)... MODELS IN GOOD AGREEMENT THROUGH THE EXTENDED WITH A COLD START THEN MODERATING TEMPS WITH GENERALLY DRY CONDITIONS THROUGH THE END OF THE WEEK. ARCTIC SFC HIGH PRESSURE THURSDAY ACROSS THE WESTERN DAKOTAS TO BRING ANOTHER ROUND OF BLO ZERO HIGH TEMPS AND NW WINDS TO COMBINE FOR DANGEROUSLY COLD WIND CHILLS THURSDAY AND FRIDAY. MODERATING TEMPS BEGIN FRIDAY WITH 500MB FLOW BECOMING LESS NORTHERLY AND A BIT MORE NWLY AS THICKNESSES RISE WITH THE DEPARTURE OF ARCTIC SFC HIGH. CLIPPER SYSTEM WILL BRING A SCHC OF -SN ON FRI/SAT WITH A RETURN TO THE UPPER TEENS AND LOW 20S FOR NEXT SUNDAY. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...FREEZING RAIN ADVISORY UNTIL NOON CST TODAY FOR NDZ027>030-038- 039-049-052-053. WINTER STORM WATCH FROM 3 PM CST THIS AFTERNOON THROUGH LATE TONIGHT FOR NDZ052-053. MN...FREEZING RAIN ADVISORY UNTIL NOON CST TODAY FOR MNZ001>003- 013>016-022>024-027>032-040. WINTER STORM WATCH FROM 3 PM CST THIS AFTERNOON THROUGH LATE TONIGHT FOR MNZ003-016-017-022>024-027>032-040. && $$ TG/JK
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
428 AM CST MON JAN 28 2013 .UPDATE...DID NOT WANT TO COMPLICATE THINGS ANY MORE...BUT GETTING REPORTS OF FREEZING DRIZZLE ACROSS THE SOUTHERN HALF OF THE FORECAST AREA RESULTING IN ICY ROADS. WILL NEED TO ISSUE A FREEZING RAIN ADVISORY (FOR FREEZING DRIZZLE) THROUGH THE MORNING HOURS. SNOW SHOWERS WILL MOVE ACROSS THE NORTHERN PART OF THIS ADVISORY OVER THE NEXT FEW HOURS...WHICH WILL LIKELY END THE FREEZING DRIZZLE HERE. LATEST RAP INDICATES VISIBILITY WILL IMPROVE ACROSS THE SOUTHERN PART OF THIS ADVISORY BY NOON...WHICH SHOULD CORRESPOND TO THE END OF THE FREEZING DRIZZLE. && .AVIATION...EXPECT MVFR/IFR CONDITIONS TO AFFECT AREAS ALONG AND EAST OF THE RED RIVER VALLEY THROUGH THE MORNING HOURS. THE NORTHERN/WESTERN EDGE OF THESE LOW CIGS WILL LIKELY ADVECT EASTWARD THIS AFTERNOON...WITH VFR CONDITIONS POSSIBLY MOVING INTO KGFK/KTVF BY LATE AFTERNOON. FREEZING DRIZZLE POSSIBLE THROUGH THE MORNING HOURS...THE A BAND OF HEAVIER SNOW WILL MOVE INTO WEST CENTRAL MINNESOTA LATER THIS AFTERNOON. WINDS WILL REMAIN LIGHT THROUGH THE PERIOD. && .PREV DISCUSSION... /ISSUED 335 AM CST MON JAN 28 2013/ SHORT TERM (TODAY-WED NIGHT)...THE MAIN CONCERN THIS PERIOD WILL BE THE POTENTIAL OF A HEAVY SNOW BAND ACROSS THE SOUTHEAST FA. 00Z MODELS IN DECENT AGREEMENT AND WILL USE A BLEND. A COUPLE SHORTWAVES IN SOUTHWEST FLOW ALOFT WILL AFFECT THE REGION TODAY. THE FIRST SHORTWAVE IS CURRENTLY (09Z) ALONG THE SOUTH DAKOTA/NORTH DAKOTA BORDER...AND WILL CONTINUE TO PROPAGATE NE THROUGH THE DAY. THERE IS AN AREA OF SCATTERED SNOW SHOWERS ASSOCIATED WITH THIS FEATURE...AND WILL INCLUDE 50% POPS ACROSS THE NORTHERN FA THIS MORNING. EXPECT FOG THROUGH THE MORNING HOURS ACROSS THE SOUTHERN FA ASSOCIATED WITH HIGHER SURFACE MOISTURE. THERE HAVE BEEN NO REPORTS OF FREEZING DRIZZLE...AND MOST VISIBILITIES ARE 1/2SM OR GREATER. WILL MONITOR...BUT FOR NOW NO HEADLINES ARE NEEDED THROUGH THE MORNING HOURS. ATTENTION THEN TURNS TO THE NEXT SHORTWAVE THAT WILL EJECT FROM THE WEST COAST TROUGH AND INTO THE NORTHERN PLAINS. THIS FEATURE WILL INDUCE MID-LEVEL FRONTOGENESIS AND LEAD TO A BAND OF PRECIP BY LATE AFTERNOON...CONTINUING INTO THE OVERNIGHT HOURS. MODELS ARE IN GENERAL AGREEMENT WITH THE LOCATION OF THIS BAND...GENERALLY FROM THE EXTREME SOUTHERN RED RIVER VALLEY INTO THE PARK RAPIDS AREA (CONTINUING TO THE NORTHEAST). THE ECMWF/GFS ARE SLIGHTLY NORTH OF THE NAM/RAP WITH PLACEMENT. THE ECMWF/GFS SHOW 0.50-0.70 INCHES QPF WITHIN THE HEAVIEST BAND...WHILE THE NAM/4-KM WRF SHOW 0.80-1.00 INCHES QPF WITHIN THE HEAVIEST BAND. CONDITIONAL INSTABILITY PARAMETERS ARE FAVORABLE...SUGGESTING THAT THE HIGHER RESOLUTION MODELS MAY BE MORE CORRECT (HIGHER QPF). 850MB TEMPS WILL BE ABOVE FREEZING AS THE PRECIP BEGINS...BUT SHOULD QUICKLY COOL TO BELOW FREEZING. A BRIEF PERIOD OF FREEZING RAIN WILL BE POSSIBLE BEFORE CHANGING OVER TO SNOW. SNOW RATIO VALUES WILL BE LOW (MORE TOWARD 10:1-12:1). FINAL SNOW AMOUNTS WILL DEPEND UPON THE DURATION OF THE FREEZING RAIN BEFORE CHANGING TO SNOW. THE OTHER CHALLENGING ASPECT OF THESE EVENTS IS THAT THE HEAVIEST BAND OF SNOW IS QUITE NARROW. THE POTENTIAL EXISTS FOR 6-12 INCHES WITHIN THE HEAVIEST BAND...WITH LIGHTER AMOUNTS ON EITHER SIDE...BUT NOT EXACTLY SURE WHERE THE HEAVIEST BAND WILL BE LOCATED. STILL A FEW QUESTIONS WITH THIS EVENT...AND THE SMART THING TO DO AT THIS POINT WILL BE A WINTER STORM WATCH ACROSS THE AREA WHERE THE HEAVY SNOW IS POSSIBLE. TUESDAY-WEDNESDAY NIGHT...MID-UPPER LEVEL TROUGH WILL PASS THROUGH THE REGION TUESDAY NIGHT WITH A COLD FRONT PASSING THROUGH. WILL NEED TO WATCH WINDS TUE NIGHT AS THE COLD FRONT MOVES THROUGH. THERE SHOULD ALSO BE AN AREA OF SNOW SHOWERS. ABOVE NORMAL TEMPS WILL TRANSITION TO BELOW NORMAL BY WEDNESDAY. LONG TERM (THURSDAY-SUNDAY)... MODELS IN GOOD AGREEMENT THROUGH THE EXTENDED WITH A COLD START THEN MODERATING TEMPS WITH GENERALLY DRY CONDITIONS THROUGH THE END OF THE WEEK. ARCTIC SFC HIGH PRESSURE THURSDAY ACROSS THE WESTERN DAKOTAS TO BRING ANOTHER ROUND OF BLO ZERO HIGH TEMPS AND NW WINDS TO COMBINE FOR DANGEROUSLY COLD WIND CHILLS THURSDAY AND FRIDAY. MODERATING TEMPS BEGIN FRIDAY WITH 500MB FLOW BECOMING LESS NORTHERLY AND A BIT MORE NWLY AS THICKNESSES RISE WITH THE DEPARTURE OF ARCTIC SFC HIGH. CLIPPER SYSTEM WILL BRING A SCHC OF -SN ON FRI/SAT WITH A RETURN TO THE UPPER TEENS AND LOW 20S FOR NEXT SUNDAY. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...FREEZING RAIN ADVISORY UNTIL NOON CST TODAY FOR NDZ027>030-038- 039-049-052-053. WINTER STORM WATCH FROM 3 PM CST THIS AFTERNOON THROUGH LATE TONIGHT FOR NDZ052-053. MN...FREEZING RAIN ADVISORY UNTIL NOON CST TODAY FOR MNZ001>003- 022>024-027>032-040. WINTER STORM WATCH FROM 3 PM CST THIS AFTERNOON THROUGH LATE TONIGHT FOR MNZ003-016-017-022>024-027>032-040. && $$ TG/JK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1001 PM CST SUN JAN 27 2013 .DISCUSSION... NO MAJOR CHANGES PLANNED WITH THIS FORECAST UPDATE. THIS BIGGEST CHALLENGE IS IF A DENSE FOG ADVISORY WILL BECOME NECESSARY ACROSS THE JAMES RIVER VALLEY UNDERNEATH AN EXPANDING STRATUS DECK. FOR NOW...WILL HOLD OFF ON AN ADVISORY. THAT SAID...THE LATEST RUNS OF THE HRRR SUGGEST VISIBILITIES POTENTIALLY FALLING TO A QUARTER MILE OR LESS...WITH KABR AND KHON ALREADY AT THESE LEVELS. WILL CONTINUE TO MONITOR TRENDS SHOULD A ADVISORY BECOME NECESSARY. && .AVIATION... AS OF 04 UTC...A WEAK FRONTAL BOUNDARY WAS LOCATED BETWEEN THE KDIK/KISN AND THE KMOT/KBIS TERMINALS. A BAND OF PRECIPITATION WAS DEVELOPING BEHIND THIS BOUNDARY. PRECIPITATION MAY START AS A MIX OF SNOW...SLEET AND FREEZING RAIN...QUICKLY CHANGING OVER TO ALL SNOW. IFR CIGS/VISIBILITIES IN STRATUS...FOG AND SNOW CURRENTLY IMPACTING KISN AND KDIK ARE FORECAST TO SOON IMPACT KMOT AND KBIS BY 06-08 UTC. FOR KJMS...MVFR/IFR CEILINGS WITH PATCHY FOG IS EXPECTED WITH INCREASING LOW LEVEL MOISTURE. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM/AVIATION...AYD
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
952 PM EST TUE JAN 29 2013 .SYNOPSIS... WARM TEMPERATURES WILL BE IN PLACE AHEAD OF A COLD FRONT THAT WILL ARRIVE WEDNESDAY. STRONG STORMS ORGANIZED AHEAD OF THE FRONT WILL AFFECT OUR AREA DURING THE EARLY TO MID MORNING HOURS WEDNESDAY. BEHIND THIS SYSTEM...COLDER AIR WILL RETURN TO THE REGION FOR THE REMAINDER OF THE WEEK. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... MODELS KEEP OFFERING SUBTLE TIMING ISSUES FOR THE ARRIVAL OF A PREFRONTAL TROUGH LATE TONIGHT INTO WEDNESDAY MORNING THAT WILL MOSTLY LIKELY BE REALIZED AS A WELL DEFINED BAND OF SHOWERS AND EMBEDDED THUNDERSTORMS. DID NOT WANT TO MESS WITH THE TIMING TOO MUCH UNTIL WE CAN GET A MORE DEFINED TRACK TO OUR WEST AND WITH A CHANCE TO LOOK AT THE FULL SUITE OF MODELS BOTH HIGH RES/CONVECTIVE ALLOWING AND LOWER RES/CONVECTIVE PARAMETERIZATION. IT APPEARS THAT THE LATEST 00Z NAM-WRF TRICKLING IN IS NOT DEPICTING ANY MUCAPE WITH CURRENT CONVECTION TO OUR WEST/NORTHWEST WHILE THE LATEST RAP AT LEAST SHOWS 200-400 J/KG. BY THE TIME THE LINE ARRIVES LATE TONIGHT INTO WEDNESDAY...BEST ESTIMATE OF MUCAPE SHOULD STILL BE IN THE 200-400 J/KG. EVEN IF THIS DOES NOT RESULT IN MUCH LIGHTNING ACTIVITY...A VERY STRONG 925 MB TO 850 MB LOW LEVEL JET WILL ACCOMPANY IT...AND IT CAN NOT BE TAKEN LIGHTLY. IT WOULD NOT TAKE MUCH FOR CONVECTIVE DOWNDRAFTS TO BRING DOWN 50 KNOT WINDS TO THE SURFACE WHEN THEY ARE FORECAST TO BE IN THE LOWER 50S KNOTS AROUND 1500 FEET. SO...CURRENT HWO HIGHLIGHTS THIS. ANOTHER CONCERN WILL BE THE THREAT FOR HIGHER WIND GUSTS BEFORE THE LINE OF ARRIVES SHOULD SOME STRAY SHOWER ACTIVITY PRECEDE IT WHICH MAY BRING DOWN STRONGER WINDS DUE TO LIGHT SPRINKLES OR VIRGA. WILL CONTINUE TO MONITOR THIS. TEMPERATURES OVERNIGHT WILL REMAIN VERY WARM DUE TO INCREASING SOUTHERLY FLOW AHEAD OF THE PREFRONTAL TROUGH AND SHOULD BOTTOM OUT IN THE UPPER 50S TO THE LOWER 60S BY SUNRISE. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... BEHIND THE LEADING EDGE OF THIS CONVECTIVE COMPLEX WILL BE AN AREA OF MORE STRATIFORM PRECIPITATION AND LIGHTER WINDS THAT WILL LAST INTO THE MID MORNING HOURS IN THE WEST...AND THE EARLY AFTERNOON IN THE EAST. ALL THIS ACTIVITY WILL BE PRE-FRONTAL...THEREFORE A MARKED TEMPERATURE DECREASE WILL NOT BE EXPECTED UNTIL LATER IN THE AFTERNOON AS THE FRONT PASSES. SOME SHOWER ACTIVITY IS EXPECTED AS THE FRONT PASSES WITH A WIND SHIFT OUT THE NORTHWEST. WINDS WILL BECOME GUSTY FROM THE AFTERNOON INTO THE LATE EVENING BEHIND THE FRONT. WITH THE LOW RAPIDLY DEPARTING...DO NOT EXPECT WINDS TO GUST MUCH OVER 40 MPH BEHIND THE FRONT. CAA SNOW SHOWERS WILL BE POSSIBLE DURING THE EVENING BEHIND THE FRONT...BEFORE THE ORIENTATION OF THE FLOW BECOMES MORE WESTERLY...ENDING ANY SNOW SHOWERS LATE WEDNESDAY NIGHT. BREEZY CONDITIONS WILL CONTINUE THURSDAY AS HIGH PRESSURE TRIES TO BUILD SOUTHEASTWARD ACROSS THE PLAINS. A WEAK DISTURBANCE RIDING UNDERNEATH THE BASE OF A DEEP TROUGH CENTERED OVER EASTERN CANADA WILL PASS ACROSS OUR AREA THURSDAY NIGHT. MODELS VARY A BIT IN THEIR STRENGTH OF THIS FEATURE AND IN THE MOISTURE AVAILABLE FOR IT TO WORK WITH. CURRENT INDICATIONS ARE THAT SOME OF OUR FORECAST AREA...PARTICULARLY THE SOUTH...MAY SEE SOME SNOW OVERNIGHT THURSDAY NIGHT. && .LONG TERM /FRIDAY THROUGH TUESDAY/... A SHORTWAVE WILL BE DEPARTING THE GREAT LAKES REGION ON FRIDAY...WITH CLOUDS REMAINING OVER THE UPPER OHIO VALLEY TO START THE PERIOD. IT APPEARS THAT THE SNOW WILL BE LIMITED TO AREAS NORTHEAST OF THE ILN CWA BY FRIDAY...SO NO POPS HAVE BEEN INCLUDED IN THE FORECAST. THE AIR MASS ON FRIDAY WILL BE VERY COLD...WITH 850MB TEMPERATURES OVER THE CWA RANGING FROM -16 TO -20 DEGREES CELSIUS. STANDARDIZED ANOMALIES INDICATE THESE TEMPERATURES APPROACH 2 STANDARD DEVIATIONS BELOW NORMAL...NOT AS SIGNIFICANT AS THE ARCTIC AIR LAST WEEK...BUT STILL RATHER COLD. MAX TEMPS ON FRIDAY HAVE BEEN LOWERED SLIGHTLY...THOUGH NOT AS COLD AS THE RAW GFS. THROUGH THE REST OF THE PERIOD...OVERALL MODEL AGREEMENT IN THE LARGE-SCALE PATTERN IS GOOD THROUGH MONDAY. ON MONDAY AND LATER...GFSE SPREADS BECOME FAIRLY LARGE...WITH LESS CERTAINTY IN THE STRENGTH AND TIMING OF THE NEXT WEATHER SYSTEMS TO IMPACT THE REGION. ON SATURDAY...A WEAK NORTHWEST FLOW SYSTEM WILL MOVE THROUGH THE REGION. WITH SOME INCREASING CONFIDENCE IN THE TIMING OF THIS SYSTEM...POPS WERE INCREASED WELL INTO THE CHANCE CATEGORY FOR THE WHOLE CWA. VERIFYING AS CURRENTLY DEPICTED IN THE MODELS...THIS SYSTEM COULD PRODUCE AN INCH OR TWO OF SNOW. TEMPERATURES WILL GRADUALLY MODERATE OVER THE NEXT FEW DAYS...AS SURFACE HIGH PRESSURE BUILDS IN BEHIND THE SATURDAY SYSTEM. THE TEMPERATURE FORECAST HAS BEEN INCREASED SLIGHTLY THROUGH MONDAY. A COLD FRONT IS FORECAST TO MOVE THROUGH THE CWA ON MONDAY NIGHT. WHILE THE GFS/ECMWF ARE IN DECENT AGREEMENT ON TIMING...THE STRENGTH OF THE FRONT AND AMOUNT OF MOISTURE AVAILABLE REMAIN UNCERTAIN. TEMPERATURES WITH THIS FRONT WILL LIKELY SUPPORT A MIX OF RAIN OR SNOW...WITH NOTHING INDICATING ICY PRECIPITATION AT THIS TIME. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... A VERY DYNAMIC WEATHER SYSTEM WILL AFFECT THE GREAT LAKES AND OHIO VALLEY REGION THROUGH THE TAF PERIOD. LOW PRESSURE OVER MISSOURI WILL DEEPEN AS IT MOVES NORTHEAST TO WESTERN LOWER MICHIGAN BY 12Z WEDNESDAY...THEN IT WILL CONTINUE TO A POSITION NEAR SOUTHERN ONTARIO BY 00Z THURSDAY. THERE WILL BE SEVERAL AVIATION ISSUES WITH THIS SYSTEM. THE FIRST WILL BE A PREFRONTAL TROUGH THAT IS FORECAST TO MOVE IN ADVANCE OF THE COLD FRONT ACROSS THE REGION BETWEEN 09Z AND 15Z. THIS FEATURE WILL LIKELY EXHIBIT A WELL DEFINED BAND OF SHOWERS AND POSSIBLY SOME EMBEDDED THUNDERSTORMS. THE FEATURE WILL BE MOVING WITHIN A VERY STRONG WIND REGIME WITH WINDS FORECAST TO BE IN THE LOWER 50 KNOTS NEAR 1500 FEET AND OVER 80 KNOTS NEAR 4000 FEET. AS SUCH...THE THREAT EXISTS FOR SOME WIND GUSTS TO SURPASS 50 KNOTS AT THE SURFACE WHERE CONVECTIVE DOWNDRAFTS OCCUR. AT THIS TIME...HAVE INTRODUCED WIDESPREAD SHOWERS WITH MVFR/IFR CEILINGS/VSBYS WITH THE VCTS/CB DESCRIPTORS AS IT IS STILL TOO EARLY TO PINPOINT WHICH TAFS MAY ACTUALLY EXPERIENCE THUNDER. ALSO...HAVE CONTINUED WITH THE 40 KNOT WIND GUSTS WITH THIS LINE OF CONVECTION...ALLOWING SHORT TERM OBSERVATIONS DICTATE WHETHER THESE VALUES NEED TO BE ADJUSTED UPWARD AS THE FEATURE MOVES THROUGH THE REGION. ONCE THIS PREFRONTAL TROUGH PASSES BY...WE SHOULD GET INTO A PERIOD OF SHOWERS WITH MVFR CONDITIONS. THEREAFTER...MODELS SUGGEST A LULL IN THE ACTIVITY UNTIL A STRONG COLD FRONT PUSHES EAST ACROSS THE AREA FROM LATE WEDNESDAY AFTERNOON INTO THE EVENING. THIS WILL USHER IN COLDER AIR WITH THE THREAT OF A FEW SNOW SHOWERS FOLLOWING ITS PASSAGE. AVIATORS CAN ALSO EXPECT BREEZY TO WINDY CONDITIONS OUTSIDE OF CONVECTION WITH THE WORST PROLONGED AND HIGHEST WIND GUSTS OCCURRING IN THE COLD AIR ADVECTION BEHIND THE COLD FRONT WHERE WINDS COULD GUST AS HIGH AS 35 KNOTS. OUTLOOK...BREEZY TO WINDY CONDITIONS TO CONTINUE WEDNESDAY NIGHT INTO THURSDAY. MVFR CEILINGS TO CONTINUE THURSDAY INTO THURSDAY NIGHT WITH MVFR VSBYS POSSIBLE THURSDAY NIGHT. MVFR CONDITIONS POSSIBLE AGAIN SATURDAY INTO SUNDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HICKMAN/LATTO NEAR TERM...HICKMAN/LATTO SHORT TERM...LATTO LONG TERM...HATZOS AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
839 PM CST TUE JAN 29 2013 .UPDATE... VWP CONTINUING TO SHOW A GRADUAL INCREASE IN WIND SPEEDS...PARTICULARLY SEVERAL THOUSAND FEET ABOVE GROUND. MODELS STILL INDICATING SOME LOWER LEVEL SUBSIDENCE OUT AHEAD OF THE CONVECTION TO OUR WEST. LATEST TN STATE ROUNDUP SHOWING SOME 30 TO 35 MPH GUSTS ACROSS WESTERN TN. THESE HIGHER SPEEDS WILL CONTINUE TO MOVE OUR WAY OVERNIGHT. CONVECTION WISE...TWO MAIN AREAS OF PRE FRONTAL FORCING INDICATED ACROSS CENTRAL AND EASTERN AR NOW. ITS LOOKING AS THOUGH THE LEADING LINE WILL REACH THE MS RIVER AROUND 04Z OR 05Z. THERE IS A LEADING AREA OF CONVECTION ACROSS NRN MS BUT IT APPEARS TO BE OUTRUNNING THE BETTER INSTABILITY AT THIS TIME. LATEST HRRR DATA SHOWS THE MAIN LINE OF STORMS REACHING THE TN RIVER AROUND 08Z. LATEST NAM DATA STILL SHOWING A GOOD DEAL OF INSTABILITY WITH NEG SHOWALTER VALUES TRAVERSING THE AREA. FURTHERMORE...HELICITY VALUES REMAIN QUITE HIGH. THUS...THE TORNADO WATCHES TO OUR WEST ARE LIKELY TO PROPAGATE EASTWARD OVERNIGHT. NAM CONTINUES TO RUN A FEW HOURS TOO SLOW WITH THE EXPECTED CONVECTION. NEAR 60 DEW POINTS NOW COVER THE BULK OF OUR AREA...WITH SOME LOWER TO MID 60S DEWPOINTS ACROSS SOUTHERN MIDDLE TN. NO ADDITIONAL UPDATES TO THE ZONES ARE NEEDED FOR NOW. THERE COULD STILL BE SOME PRE MIDNIGHT CONVECTION...BUT THE BULK OF THE ACTIVITY WILL BE AFTER MIDNIGHT. UPDATES TO COMMENCE WITH THE LIKELY INTRODUCTION OF CONVECTIVE WATCH BOXES LATER TONIGHT. && .PREV DISCUSSION... /ISSUED 614 PM CST TUE JAN 29 2013/ UPDATE...00Z AVIATION DISCUSSION. AVIATION...00Z AVIATION DISCUSSION. SFC PRESSURE GRADIENT WILL CONTINUE TO INCREASE AS APPROACHING COLD FRONTS MOVE INTO/ACROSS MID STATE DURING 30/12Z-30/24Z. ALSO...STRONG LOW LEVEL WIND SHEAR JUST OFF SFC WITH SLY WINDS 60KT-70KT EXPECTED THRU AROUND 30/12Z... WITH SOME SFC GUSTS TO AROUND 45KT EVEN POSSIBLE ALONG LEADING EDGE. A LINE OF STORMS...AT LEAST IN VCNTY OF COLD FRONTAL PASSAGE...AND MAY ALSO FORM OUT AHEAD...AS MOISTURE...INSTABILITY...AND LIFTING MECHANISMS COME INTO PLAY...AND THEN QUICKLY MOVE NEWD. EXPECT IMPACTS AT CKV AROUND 30/07Z... BNA 30/08Z...AND CSV 30/11Z. SOME HEAVY RAINFALL WILL ALSO ACCOMPANY THE STRONGER STORMS WITH SVR TSTMS POSSIBLY ALSO OUT AHEAD AND EMBEDDED IN LINE. TIMING AND DURATION OF THE LINE OF STORMS IS STILL UNCERTAIN...HOWEVER CKV/BNA CAN EXPECT THE STRONGEST STORMS TO MOVE OUT OF THE AREA BETWEEN 30/11-30/12Z. CSV MAY CONTINUE TO EXPERIENCE STRONGEST STORMS UNTIL AROUND 30/15Z. WINDS ARE STILL EXPECTED TO REMAIN AROUND 20 KTS WITH GUSTS TO 30 KTS FOR AREA THRU 30/24Z. CHANGE OVER TO ALL SHWRS IS EXPECTED W TO E DURING THE 30/18Z-30/24Z TOO. PREV DISCUSSION.../ISSUED 536 PM CST TUE JAN 29 2013/ UPDATE... MAIN FRONTAL BOUNDARY EXTENDS FROM CENTRAL MO SW THROUGH EASTERN OK. SEVERAL PRE FRONTAL BOUNDARIES IN ADVANCE OF THIS FEATURE WITH THE MAIN LINE OF CONVECTION CURRENTLY OVER NW AR. INSTABILITY AXIS WILL CONTINUE TO TRANSFER EASTWARD OVERNIGHT WITH THE MAIN LINE OF STORMS REACHING FAR WESTERN TN BETWEEN 03Z AND 07Z. IN ADVANCE OF THIS HOWEVER...CONVECTION STILL POSSIBLE AND WE ARE ALREADY SEEING SOME SHOWER AND TSTM ACTIVITY INTO PORTIONS OF EASTERN AR. GFS LOOKING A LITTLE FAST WITH THE MAIN LINE WHILE THE NAM MAY BE A LITTLE SLOW. BUT...THE MODELS ARE IN AGREEMENT WITH A VERY STRONG LINEAR OMEGA FIELD MATCHING UP WITH A POWERFUL 70-80 KT 850 MB JET. FURTHERMORE...SHOWALTERS AT OR JUST BELOW ZERO WILL ALIGN WITH AN IMPRESSIVE LOW TO MID LEVEL THETA-E AXIS TO HELP PROPEL THE CONVECTION. IN ADDITION TO THE SEVERE WEATHER THREAT...THE PRESSURE GRADIENT IS EXPECTED TO TIGHTEN UP BETWEEN NOW AND THROUGH 06Z. GOOD LOWER LEVEL SUBSIDENCE IS INDICATED AS THE WINDS ALOFT BEGIN TO STRENGTHEN. THUS...GUSTS TO 35 OR 40 MPH SHOULD BE EASY TO REACH OVERNIGHT. FOR THE UPDATE...WILL ATTEMPT TO ADJUST GRIDS SO AS TO INCREASE THE WIND SPEEDS IN THE ZONE TEXT. REMAINDER OF FCST IS IN GOOD SHAPE. THREAT OF STORMS DOES EXIST AHEAD OF THE MAIN LINE SO WILL LEAVE THE DAMAGE POTENTIAL IN PRIOR TO MIDNIGHT FOR NOW. UPDATE OUT SHORTLY. PREV DISCUSSION... /ISSUED 349 PM CST TUE JAN 29 2013/ DISCUSSION... THE FRONTAL PASSAGE AND ASSOCIATED SQUALL LINE WILL BE THE FOCUS OF THE FORECAST. LOW LEVEL WINDS ARE EXPECTED TO CONTINUE TO INCREASE AHEAD OF THE APPROACHING SYSTEM. A WIND ADVISORY CONTINUES FOR AREAS WEST OF THE PLATEAU UNTIL 6 PM WEDNESDAY...WHILE AREAS ALONG THE PLATEAU ARE UNDER A WIND ADVISORY STARTING AT 6 PM TONIGHT AND LASTING THROUGH 9 PM WEDNESDAY. SUSTAINED 25 MPH WINDS ARE POSSIBLE WITH GUSTS TO 45 MPH. PLENTY OF MOISTURE AND WARM AIR WILL CONTINUE TO SURGE INTO MIDDLE TN AHEAD OF THE SYSTEM. A FEW ISOLATED SHOWERS MAY BE POSSIBLE AHEAD OF THE LINE...BEFORE MIDNIGHT. HOWEVER THE MAIN THREAT REMAINS WITHIN AND AROUND THE EXPECTED SQUALL LINE...WITH THE MAIN CONCERNS BEING DAMAGING STRAIGHT LINE WINDS AND QLCS TORNADOES. THE ETA OF THE MAIN ACTIVITY WILL BE 11 PM TO 2 AM FOR AREAS NEAR THE TENNESSEE RIVER....1 AM TO 4 AM FOR AREAS ALONG THE I-65 CORRIDOR AND 4 AM TO 9 AM FOR AREAS ALONG AND NEAR THE CUMBERLAND PLATEAU. PWAT VALUES STILL REMAIN RELATIVELY HIGH FOR THIS TIME OF YEAR, HOWEVER DUE TO THE RATHER QUICK MOVEMENT OF THE STORM SYSTEM FLOODING DOES NOT APPEAR TO BE A MAJOR ISSUE. 1 TO 1.5 INCHES OF RAINFALL WILL BE POSSIBLE ACROSS THE AREA WITH LOCALLY HIGHER AMOUNTS WITHIN THE STRONGEST CELLS. BECAUSE THE GROUND WILL BE FAIRLY SATURATED EVEN SUB-SEVERE WIND GUSTS COULD CAUSE TREES TO TOPPLE OVER. THE MAIN LINE OF STORMS IS EXPECTED TO EXIT THE PLATEAU BY MID MORNING ON WEDNESDAY. SOME SHOWERS MAY LINGER AROUND THE MID STATE INTO THE AFTERNOON...AFTER THE DEPARTURE OF THE MAIN LINE OF STORMS...BUT BY LATE AFTERNOON THE WINDS WILL BEGIN TO SHIFT FROM SOUTHERLY TO WESTERLY...USHERING COLDER DRIER AIR INTO THE AREA FROM THE WEST. BY WEDNESDAY NIGHT PRECIPITATION WILL TAPER OFF WEST TO EAST...WITH A RAIN SNOW MIX TRANSITIONING TO LIGHT SNOW SHOWERS OR FLURRIES OVER THE PLATEAU AND HIGHER TERRAIN LATE. COLD AIR ADVECTION PEAKS WITH 850MB TEMPS DROPPING TO ABOUT -8C ON WEDNESDAY AS BROAD UPPER TROUGH OVER THE CONUS PERSISTS. EXPECT MARGINAL WARMING ON THURSDAY BEFORE A WEAK BUT QUICK MOVING SHORTWAVE ROTATES AROUND THE TROUGH THURSDAY NIGHT BRINGING THE POSSIBILITY OF LIGHT SNOWFALL TO THE AREA. LACK OF MOISTURE SHOULD KEEP ACCUMULATIONS DOWN...RANGING FROM A DUSTING TO A HALF INCH OVER THE LOWER ELEVATIONS...TO AROUND AN INCH OVER PORTIONS OF THE PLATEAU. THIS SYSTEM COULD STRENGTHEN OR WEAKEN WITH SUBSEQUENT MODEL RUNS...SO EXPECT CHANGES AS THE FORECAST TIME DRAWS NEAR. FOR FRIDAY...NORTHWESTERLY WINDS OF 5-10KTS ALONG WITH COLD AIR ADVECTION DROPPING 925MB TEMPS TO -8C TO -12C SHOULD MAKE FOR AN UNPLEASANT DAY. BUNDLE UP. BY THE WEEKEND...THE UPPER TROUGH LIFTS SLIGHTLY ALLOWING FOR A BIT OF WARMING...BUT ANOTHER WEAK SHORTWAVE ROTATES AROUND AND BRINGS PRECIPITATION BACK TO THE MID-STATE. THE WARMING SHOULD BE ENOUGH TO CHANGE EXPECTED PRECIP TO LIGHT RAIN SHOWERS...THOUGH A RAIN-SNOW MIX IS EXPECTED OVER THE HIGHER TERRAIN. LONG-RANGE MODELS INDICATE AN UPPER TROUGH WILL DEVELOP OVER THE CENTRAL STATES ALLOWING FOR A SOUTHERLY FLOW TO BRING WARM AND MOIST AIR BACK TO THE MID-STATE. AT THIS POINT ITS UNCERTAIN HOW MUCH WILL OCCUR...SO WILL LIMIT WEATHER TO CHANCE OF RAIN SHOWERS...AND WILL MONITOR MODEL UPDATES FOR THUNDERSTORM POTENTIAL. && .OHX WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 9 PM CST WEDNESDAY FOR TNZ011-032>034-065- 066-078>080. WIND ADVISORY UNTIL 6 PM CST WEDNESDAY FOR TNZ005>010-022>031- 056>064-075-077-093>095. && $$ 21
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
838 PM CST TUE JAN 29 2013 .UPDATE... EVENING FORECAST UPDATE. && .DISCUSSION... GUST FRONT...LINE OF STORMS...PACIFIC FRONT ARE ALL MOVING INTO SE TX BASICALLY FROM NACOGDOCHES TO HUNTSVILLE TO BELLVILLE THIS EVENING. GUST FRONT MAY BRING SOME GUSTY WINDS OF 30-40KTS BUT WINDS SHOULD BE FAIRLY BRIEF. STRONGEST STORM CONTINUES TO PUSH THROUGH WALKER CO RATHER QUICKLY. MAIN THREAT WILL BE DAMAGING WINDS BUT THINK WINDS WILL REMAIN BELOW SEVERE LEVELS. INSTABILITY SEEMS RATHER LIMITED AND CAPPING IS JUST ENOUGH TO INHIBIT DEEP CONVECTION. UPDATED POPS FOR ONGOING TRENDS. MAY NEED TO UPDATE LATER THIS EVENING AS LINE OF STORMS PUSHES TOWARDS HOUSTON. REALLY JUST EXPECTING A THIN LINE OF SHOWERS AND A FEW STORMS. REST OF THE FORECAST LOOKS ON TRACK. 39 && .PREV DISCUSSION... /ISSUED 539 PM CST TUE JAN 29 2013/ DISCUSSION... SEE 00Z AVIATION DISCUSSION. AVIATION... NOT MANY CHANGES TO PREVIOUS TAF PACKAGE. FCST SOUNDINGS SHOW A STOUT CAP IN PLACE...ESPECIALLY SOUTHERN TAF SITES. LATEST RAP 13 SHOWS THE CAP ERODING QUICKLY AND SCT SHRA/TSRA BETWEEN 03-06Z OVER THE HOUSTON TERMINALS. THE RAP SEEMS TO AGGRESSIVE WITH BREAKING THE CAP SO LEANED TOWARD THE MORE STABLE AND CAPPED NAM/GFS. MVFR CIGS POSSIBLE THIS EVENING WITH VFR CONDS EXPECTED TO DEVELOP BETWEEN 06-09Z. BUMPED WINDS UP A BIT FOR WEDNESDAY AND CONTINUED TREND WITH WRAP AROUND CLOUD COVER WITH SCT-BKN CONDS POSSIBLE OVER NORTHERN TAF SITES. 43 PREV DISCUSSION... /ISSUED 329 PM CST TUE JAN 29 2013/ DISCUSSION... IT`S BEEN ON THE BREEZY SIDE ACROSS MUCH OF SOUTHEAST TEXAS TODAY...AND CLOUD COVER HAS MANAGED TO KEEP HIGH TEMPERATURES ALMOST AREA WIDE UNDER 80 DEGREES. A LINE OF SHOWERS AND THUNDERSTORMS (SOME SEVERE) ACROSS A NORTH CENTRAL TEXAS COLD FRONT WILL BE MOVING INTO SOUTHEAST TEXAS THIS EVENING. THERE CONTINUES TO BE A RISK OF STRONG/SEVERE STORMS ACROSS THE NORTHERN HALF OF OUR AREA WHERE THE CAP IS EXPECTED TO WEAKEN. FURTHER SOUTH (SAY AROUND AND SOUTH OF I-10)...THE CAP SHOULD HOLD RESULTING IN A LOWER RISK OF SEVERE DEVELOPMENT. THESE STORMS ARE EXPECTED TO BE OFF THE COAST AROUND OR SHORTLY AFTER MIDNIGHT WITH COOLER AIR FILTERING INTO THE AREA BEHIND THE BOUNDARY. EXPECTING IT TO BE BREEZY AND COOLER ON WEDNESDAY...AND A WIND ADVISORY MIGHT BE NEEDED NEAR THE COAST/COASTAL COUNTIES. ALSO...ELEVATED FIRE WEATHER CONDITIONS ARE STILL ANTICIPATED DURING THE DAY DUE TO THE GUSTY WINDS AND VERY LOW HUMIDITIES. SURFACE HIGH PRESSURE SETTLING INTO THE AREA WEDNESDAY NIGHT AND EDGING OFF TO OUR EAST ON THURSDAY WILL BRING QUIET WEATHER TO OUR AREA. A GRADUAL WARM UP IS EXPECTED FOR THE END OF THE WEEK AND ON INTO THE WEEKEND UNDER MAINLY LIGHT SOUTH WINDS. THE NEXT COLD FRONT IS CURRENTLY EXPECTED TO MOVE THROUGH THE AREA EARLY NEXT WEEK. 42 MARINE... STRONG ONSHORE FLOW WILL PERSIST THROUGH THIS EVENING AHEAD OF AN APPROACHING COLD FRONT. THE FRONT WILL MOVE OFFSHORE AROUND MIDNIGHT AND PUSH THROUGH THE COASTAL WATERS OVERNIGHT BRINING WINDS OF 15 TO 25 KNOTS WITH HIGHER GUSTS. THUNDERSTORMS MAY BE POSSIBLE AROUND GALVESTON BAY AND THE EASTERN WATERS ALONG AND AHEAD OF THE FRONT. HAVE EXTENDED SCEC FOR GALVESTON BAY THROUGH 6PM WEDNESDAY EVENING BUT WINDS MAY INCREASE ENOUGH WEDNESDAY AFTERNOON TO SUPPORT A BRIEF SCA FOR GALVESTON BAY. ELSEWHERE...SCA CONDITIONS EXPECTED THROUGH WEDNESDAY AFTERNOON. 38 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 44 64 36 66 41 / 60 0 0 0 0 HOUSTON (IAH) 49 65 38 67 42 / 50 0 0 0 0 GALVESTON (GLS) 54 64 46 66 50 / 40 0 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL 6 PM CST WEDNESDAY FOR THE FOLLOWING ZONES: MATAGORDA BAY...WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH WEDNESDAY AFTERNOON FOR THE FOLLOWING ZONES: GALVESTON BAY. SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST WEDNESDAY NIGHT FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. && $$ DISCUSSION...39
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
539 PM CST TUE JAN 29 2013 .DISCUSSION... SEE 00Z AVIATION DISCUSSION. && .AVIATION... NOT MANY CHANGES TO PREVIOUS TAF PACKAGE. FCST SOUNDINGS SHOW A STOUT CAP IN PLACE...ESPECIALLY SOUTHERN TAF SITES. LATEST RAP 13 SHOWS THE CAP ERODING QUICKLY AND SCT SHRA/TSRA BETWEEN 03-06Z OVER THE HOUSTON TERMINALS. THE RAP SEEMS TO AGGRESSIVE WITH BREAKING THE CAP SO LEANED TOWARD THE MORE STABLE AND CAPPED NAM/GFS. MVFR CIGS POSSIBLE THIS EVENING WITH VFR CONDS EXPECTED TO DEVELOP BETWEEN 06-09Z. BUMPED WINDS UP A BIT FOR WEDNESDAY AND CONTINUED TREND WITH WRAP AROUND CLOUD COVER WITH SCT-BKN CONDS POSSIBLE OVER NORTHERN TAF SITES. 43 && .PREV DISCUSSION... /ISSUED 329 PM CST TUE JAN 29 2013/ DISCUSSION... IT`S BEEN ON THE BREEZY SIDE ACROSS MUCH OF SOUTHEAST TEXAS TODAY...AND CLOUD COVER HAS MANAGED TO KEEP HIGH TEMPERATURES ALMOST AREA WIDE UNDER 80 DEGREES. A LINE OF SHOWERS AND THUNDERSTORMS (SOME SEVERE) ACROSS A NORTH CENTRAL TEXAS COLD FRONT WILL BE MOVING INTO SOUTHEAST TEXAS THIS EVENING. THERE CONTINUES TO BE A RISK OF STRONG/SEVERE STORMS ACROSS THE NORTHERN HALF OF OUR AREA WHERE THE CAP IS EXPECTED TO WEAKEN. FURTHER SOUTH (SAY AROUND AND SOUTH OF I-10)...THE CAP SHOULD HOLD RESULTING IN A LOWER RISK OF SEVERE DEVELOPMENT. THESE STORMS ARE EXPECTED TO BE OFF THE COAST AROUND OR SHORTLY AFTER MIDNIGHT WITH COOLER AIR FILTERING INTO THE AREA BEHIND THE BOUNDARY. EXPECTING IT TO BE BREEZY AND COOLER ON WEDNESDAY...AND A WIND ADVISORY MIGHT BE NEEDED NEAR THE COAST/COASTAL COUNTIES. ALSO...ELEVATED FIRE WEATHER CONDITIONS ARE STILL ANTICIPATED DURING THE DAY DUE TO THE GUSTY WINDS AND VERY LOW HUMIDITIES. SURFACE HIGH PRESSURE SETTLING INTO THE AREA WEDNESDAY NIGHT AND EDGING OFF TO OUR EAST ON THURSDAY WILL BRING QUIET WEATHER TO OUR AREA. A GRADUAL WARM UP IS EXPECTED FOR THE END OF THE WEEK AND ON INTO THE WEEKEND UNDER MAINLY LIGHT SOUTH WINDS. THE NEXT COLD FRONT IS CURRENTLY EXPECTED TO MOVE THROUGH THE AREA EARLY NEXT WEEK. 42 MARINE... STRONG ONSHORE FLOW WILL PERSIST THROUGH THIS EVENING AHEAD OF AN APPROACHING COLD FRONT. THE FRONT WILL MOVE OFFSHORE AROUND MIDNIGHT AND PUSH THROUGH THE COASTAL WATERS OVERNIGHT BRINING WINDS OF 15 TO 25 KNOTS WITH HIGHER GUSTS. THUNDERSTORMS MAY BE POSSIBLE AROUND GALVESTON BAY AND THE EASTERN WATERS ALONG AND AHEAD OF THE FRONT. HAVE EXTENDED SCEC FOR GALVESTON BAY THROUGH 6PM WEDNESDAY EVENING BUT WINDS MAY INCREASE ENOUGH WEDNESDAY AFTERNOON TO SUPPORT A BRIEF SCA FOR GALVESTON BAY. ELSEWHERE...SCA CONDITIONS EXPECTED THROUGH WEDNESDAY AFTERNOON. 38 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 44 64 36 66 41 / 60 0 0 0 0 HOUSTON (IAH) 49 65 38 67 42 / 60 0 0 0 0 GALVESTON (GLS) 54 64 46 66 50 / 50 0 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL 6 PM CST WEDNESDAY FOR THE FOLLOWING ZONES: MATAGORDA BAY...WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH WEDNESDAY AFTERNOON FOR THE FOLLOWING ZONES: GALVESTON BAY. SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST WEDNESDAY NIGHT FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. && $$ DISCUSSION...39 AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1010 PM EST TUE JAN 29 2013 .SYNOPSIS... HIGH PRESSURE WILL BRING UNSEASONABLY WARM TEMPERATURES TO THE AREA WEDNESDAY. A STRONG COLD FRONT WILL MOVE THROUGH THE REGION LATE WEDNESDAY ACCOMPANIED BY SHOWERS WITH GUSTY WINDS AND HEAVY RAIN. MUCH COLDER TEMPERATURES WILL RETURN FOR THE END OF THE WEEK INTO THE WEEKEND AS HIGH PRESSURE MOVES SOUTHEAST FROM CANADA. && .NEAR TERM /THROUGH WEDNESDAY/... AS OF 955 PM EST TUESDAY... STARTING TO SEE SOME LIGHT REFLECTIVITY IN THE SOUTHWEST COUNTIES. EXPECT COVERAGE OF LIGHT RAIN TO EXPAND...ESPECIALLY AFTER MIDNIGHT IN THE FAVORED EASTERN UPSLOPE AREAS. HAVE INCREASED PROBABILITY OF PRECIPITATION ALONG THE SOUTHERN BLUE RIDGE IN LINE WITH LATEST WRF AND RUC GUIDANCE. BASED ON EXPECTED WINDS BY WEDNESDAY AFTERNOON...ESPECIALLY LOOKING AT THE 850 MB WINDS APPROACHING 60-65 KNOTS AND SUSTAINED WINDS ON THE DAN BUFKIT REACHING 20-25 MPH...HAVE EXPANDED THE WIND ADVISORY FOR THE REST OF THE COUNTY WARNING AREA. ALSO STRETCHED TIME OF HIGH WIND WARNING IN THE SOUTHWEST COUNTIES TO START AT 09Z. EXPECTING IT WILL NOT TAKE AS LONG AS 6AM TO START SEEING HIGH WINDS. AS OF 300 PM EST TUESDAY... ALL AREAS ARE EXPECTED TO BE CLOUDY BY EARLY WEDNESDAY MORNING. LIGHT PRECIPITATION WILL DEVELOP BY MIDNIGHT...PRIMARILY ALONG THE CREST OF THE BLUE RIDGE SOUTHWEST OF FLOYD VA INTO NW NC. AFTER MIDNIGHT...THE FOCUS FOR THE BEST CHANCE OF RAIN WILL STILL BE ALONG THE CREST OF THE BLUE RIDGE...HOWEVER...ALL PARTS OF THE FORECAST AREA WILL HAVE AT LEAST A SLIGHT CHANCE. AS WEDNESDAY PROGRESSES...PRECIPITATION CHANCES WILL PROGRESSIVELY INCREASE AS THE FRONT APPROACHES...AND THEN CROSSES THE AREA DURING THE AFTERNOON. TRENDS OF THE LATEST MODEL GUIDANCE ARE ABOUT THREE HOURS SLOWER WITH THE TIMING OF THE PASSAGE. AS SUCH...HAVE ADJUSTED OUR POP AND WEATHER GRIDS ACCORDINGLY. WHEN THE FRONT MOVES THROUGH THE AREA...WE ARE EXPECTING A STRONG SQUALL LINE OF SHOWERS WITH LIMITED...IF ANY...THUNDER. THERE IS A CONCERN THAT SOME OF THE STRONGER SHOWERS COULD HELP BRING HIGHER WINDS DOWN TO THE SURFACE...AND BE POTENTIALLY DAMAGING. OUR OTHER CONCERN FROM WIND INCLUDES GRADIENT PREVAILING WINDS IN ADVANCE OF THE FRONT. DURING THE AFTERNOON AND EARLY EVENING HOURS...WIND GUSTS AT THE HIGHER PEAKS ALONG AND WEST OF THE BLUE RIDGE...MAY SEE WIND GUSTS IN EXCESS OF WIND ADVISORY CRITERIA...40 KTS. WE ARE REFLECTING THIS CONCERN IN A WIND ADVISORY THAT WILL BE IN EFFECT FROM NOON WEDNESDAY THROUGH MIDNIGHT. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... AS OF 345 PM EST TUESDAY... FRONTAL PASSAGE WEDNESDAY EVENING WILL BRING DRAMATIC CHANGE IN TEMPERATURE...READINGS FALLING FROM THE 50S/60S WEDNESDAY EVENING INTO THE 20S/30S DURING THE OVERNIGHT. SLUG OF FRONTAL PRECIP WILL MOVE RAPIDLY EAST ACROSS THE CWA DURING THE EVENING WITH DOWNPOUR OF RAIN PRODUCING UPWARDS OF AN INCH OF RAIN IN LESS THAN 2 HOURS TIME. THIS BURST OF HEAVY RAINFALL WITH THE FRONTAL PASSAGE WILL LIKELY RESULT IN SUDDEN RISES TO AREA STREAMS. WILL FOREGO FLOOD WATCH ATTM PER QUICK MOVEMENT OF SYSTEM AND LACK OF SUSTAINED HEAVY RAIN THREAT. THAT SAID...STILL NOT A GOOD NIGHT TO BE FLIRTING AROUND LOW WATER CROSSINGS. FRONTAL PASSAGE HAS SLOWED A BIT COMPARED TO YESTERDAYS MODEL RUNS BY ABOUT 3 HOURS. LOOKS LIKE FROPA WILL OCCUR AT BLF/TNB BETWEEN 6-8PM...7-9PM AT BCB/ROA...AND 8-10PM AT LYH/DAN. AFTER FROPA...HEAVY RAIN THREAT WILL END...WINDS SHIFTING AROUND TO THE WEST-NORTHWEST...TEMPERATURES PLUMMETING BACK TO MORE OF A WINTER FLAVOR. ANY LINGERING MOISTURE IN THE MOUNTAINS WILL CHANGE TO SNOW SHOWERS OR FLURRIES...WITH A HALF INCH TO AN INCH OF ACCUMULATION POSSIBLE AT THE HIGHER ELEVATIONS LATE WEDNESDAY NIGHT AND EARLY THURSDAY. FOR THURSDAY AND INTO THE WEEKEND...COLD UPPER LEVEL TROUGH OF LOW PRESSURE WILL SET UP SHOP OVER THE EASTERN CONUS...ANY PRECIP PRODUCTION COMING FROM DISTURBANCES WITHIN THE NORTHERN STREAM. NEXT OPPORTUNITY FOR PRECIP FROM ONE OF THESE DISTURBANCES WILL COME THURSDAY NIGHT WITH A ROUND OF SNOW SHOWERS PASSING OVER THE MOUNTAINS AROUND MIDNIGHT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 305 PM EST TUESDAY... A LONG WAVE TROF REMAINS OVER THE EASTERN CONUS FOR THE WEEKEND. SFC HIGH CENTERED ALONG THE CAROLINA COAST SATURDAY WILL MOVE EAST INTO THE ATLANTIC OCEAN. A CLIPPER-LOW AND ATTENDING SURFACE COLD FRONT APPROACHES FROM THE WEST SATURDAY AND TRAVELS ACROSS FORECAST AREA SATURDAY NIGHT INTO SUNDAY MORNING. THE GFS SUGGEST THAT A COUPLE OF INCHES OF SNOW ACCUMULATION IS POSSIBLE IN THE WESTERN UPSLOPE AREAS. THE ECMWF HINTS AT LIGHTER SNOW TOTALS. KEPT SNOW SHOWERS IN THE NORTHWEST UPSLOPE FLOW FOR SUNDAY MORNING INTO SUNDAY AFTERNOON LEANING TOWARDS GFS THEN TAPER OFF AS THE TROF AXIS MOVES FURTHER INTO THE ATLANTIC. HIGH PRESSURE BUILDS ACROSS THE REGION SUNDAY NIGHT INTO MONDAY MORNING. ANOTHER LOW PRESSURE CENTER LIFTS NORTHEAST ACROSS GREAT LAKES AND PUSHES A COLD FRONT TOWARDS OUR REGION MONDAY. THE COLD FRONT ADVANCES ACROSS OUR REGION MONDAY NIGHT INTO TUESDAY. THE GFS DEVELOPS A LOW PRESSURE CENTER OFF THE VIRGINIA COAST MONDAY NIGHT AND LIFTS IT NORTHWARD ON TUESDAY. THE GFS SOLUTION INDICATED THAT MORE SNOW...SEVERAL INCHES ARE POSSIBLE IN THE WESTERN UPSLOPE AREAS ON MONDAY NIGHT INTO TUESDAY. WENT WITH SCATTERED POPS FOR MONDAY NIGHT INTO TUESDAY AND WILL WATCH FOR FURTHER RUNS TO SEE EVOLUTION AND DETAILS OF THIS STORM FOR EARLY NEXT WEEK. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... AS OF 635 PM EST TUESDAY... WINDS WILL HINDER AVIATION OPERATIONS LATE TONIGHT INTO WEDNESDAY. QUICKLY DETERIORATING CONDITIONS WILL ALSO BE MAJOR CONCERN. TONIGHT INTO EARLY WEDNESDAY...A COLD FRONT WILL APPROACH THE REGION FROM THE WEST. 850 MB WINDS ARE EXPECTED TO INCREASE FROM THE 200 DEGREES INTO THE 5O TO 60 KT RANGE BY LATE TONIGHT...AND 70 TO 80 KT RANGE BY THE END OF THE DAY WEDNESDAY. MOISTURE WILL BE ON THE INCREASE THROUGH THE NIGHT...WITH CIGS DEVELOPING IN THE MVFR RANGE. NEAR SURFACE WINDS WILL MAINLY BE LIGHT EXCEPT AROUND KBLF WHERE SOME GUSTINESS IS EXPECTED. OTHERWISE...AND EVEN AT KBLF...ANTICIPATE STRONG LOW LEVEL SPEED SHEAR AROUND 1000 FT AGL STARTING AROUND 06Z...1AM..TONIGHT AND CONTINUING THROUGH ABOUT 14Z...9AM...WEDNESDAY WHEN LOW LEVEL MIXING HELPS TO ALLOW FOR SOME STRONGER SURFACE GUSTS. 18Z NAM AND RAP CONTINUE TO SHOW RAIN SPREADING NORTHWARD ALONG THE SOUTHERN BLUE RIDGE TONIGHT INTO WEDNESDAY. HIGH CONFIDENCE THAT RAIN WILL FORM ACROSS THE AREA TOMORROW WITHIN THE PRE- FRONTAL TROUGH. EXPECT AREAS OF RAIN ALONG AND EAST OF THE CREST OF THE BLUE RIDGE BY 15Z...10AM. STRONG COLD FRONT PUSHES THROUGH THE AREA WEDNESDAY EVENING WITH HEAVY RAIN SHOWERS...QUICKLY CHANGING TO SNOW SHOWERS IN THE WEST. SHARP WIND SHIFT WITH GUSTY CONDITIONS CONTINUING. UPSLOPE SNOW SHOWERS CONTINUE BETWEEN KBLF AND KLWB THURSDAY...CLEARING EAST OF THE BLUE RIDGE. NORTHWEST FLOW WILL PREVAIL FRIDAY THROUGH SUNDAY WITH TWO POTENTIALS FOR CLIPPER SYSTEMS TO BRING UPSLOPE SNOW TO SOUTHEAST WEST VIRGINIA AND FAVORED UPSLOPE AREAS...LATE THURSDAY NIGHT IN FRIDAY AND SATURDAY NIGHT INTO SUNDAY. ANOTHER COLD FRONT IS EXPECTED TO ARRIVE MONDAY INTO MONDAY NIGHT. WHILE TIMING AND QPF OF INDIVIDUAL CLIPPER SYSTEMS REMAIN A CHALLENGE...THERE IS A GOOD CHANCE THAT ACCUMULATING SNOWS ARE POSSIBLE FOR WESTERN UPSLOPE AREAS IN THE MOUNTAINS THIS WEEKEND INTO EARLY NEXT WEEK. && .HYDROLOGY... AN INCH /1.00/ TO AND INCH AND A HALF /1.50/ OF RAIN IS ANTICIPATED WITH THE FRONTAL PASSAGE WEDNESDAY EVENING. THE BULK OF THIS RAIN WILL BE ASSOCIATED WITH A SQUALL LINE OF SHOWERS ASSOCIATED WITH A FRONTAL PASSAGE...MOST OF THIS RAIN OCCURRING IN LESS THAN 2 HOURS. DUE TO THE SHORT DURATION OF THE HEAVY RAINFALL...EXPECT RAPID RISES ALONG AREA STREAMS. AS LONG AS THE RAINFALL AMOUNTS REMAIN BELOW 1.5 INCHES...FLOODING SHOULD BE KEPT TO A MINIMUM. ENSEMBLE FORECASTS SUGGEST THERE WILL ALSO BE SOME RESPECTABLE RISES ON THE AREA RIVERS. 1.50 INCHES OF RAIN WILL CAUSE RIVERS TO RISE TO NEAR BANKFULL. IF RAIN AMOUNTS EXCEED 1.50 INCHES OVER ANY GIVEN BASIN...THEN RIVER FLOODING WOULD BECOME AN ISSUE. ATTM...CURRENT FORECASTS REFLECT BASIN AVERAGE AMOUNTS CLOSER TO 1.25 INCHES. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WIND ADVISORY FROM NOON WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR VAZ011-013-014-016>020-022>024-032>035-043>047- 058-059. HIGH WIND WARNING FROM 4 AM WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR VAZ007-009-010-012-015. NC...WIND ADVISORY FROM NOON WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR NCZ002>006-019-020. HIGH WIND WARNING FROM 4 AM WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR NCZ001-018. WV...WIND ADVISORY FROM NOON WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR WVZ043>045. HIGH WIND WARNING FROM 4 AM WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR WVZ042. && $$ SYNOPSIS...AMS/RAB NEAR TERM...AMS/DS SHORT TERM...PM LONG TERM...KK AVIATION...DS/KK HYDROLOGY...PM
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
701 PM EST TUE JAN 29 2013 .SYNOPSIS... HIGH PRESSURE ALOFT WILL BUILD ACROSS THE EASTERN SEABOARD THROUGH WEDNESDAY BRINGING UNSEASONABLY WARM TEMPERATURES TO THE AREA. A STRONG COLD FRONT WILL MOVE THROUGH THE REGION LATE WEDNESDAY ACCOMPANIED BY SHOWERS WITH GUSTY WINDS AND HEAVY RAIN. MUCH COLDER TEMPERATURES WILL RETURN FOR THE END OF THE WEEK INTO THE WEEKEND AS HIGH PRESSURE MOVES SOUTHEAST FROM CANADA. THERE WILL BE SEVERAL CHANCES FOR LIGHT SNOW IN THE THURSDAY THROUGH SUNDAY PERIOD. && .NEAR TERM /THROUGH WEDNESDAY/... AS OF 640 PM EST TUESDAY... MADE SOME MINOR ADJUSTMENTS IN TEMPERATURES AND POPS TO REFLECT CURRENT OBS AND MODEL TRENDS. 18Z NAM AND RUC STILL SHOWED MOISTURE LIFTING NORTH ALONG THE SOUTHERN BLUE RIDGE TONIGHT. APPEARS THAT TIMING MAY BE A LITTLE SLOWER. MORE ADJUSTMENTS LATER TONIGHT. AS OF 300 PM EST TUESDAY... OVERNIGHT...SOUTHERLY FLOW WILL INCREASE ACROSS THE AREA IN ADVANCE OF AN APPROACHING STRONG UPPER TROUGH AND ASSOCIATED COLD FRONT. THIS WILL BRING ABUNDANT GULF OF MEXICO MOISTURE INTO THE REGION. THE RESULT WILL INCREASING..THICKENING AND LOWERING OF THE CLOUD COVER. ALL AREAS ARE EXPECTED TO BE CLOUDY BY EARLY WEDNESDAY MORNING. LIGHT PRECIPITATION WILL DEVELOP BY MIDNIGHT...PRIMARILY ALONG THE CREST OF THE BLUE RIDGE SOUTHWEST OF FLOYD VA INTO NW NC. AFTER MIDNIGHT...THE FOCUS FOR THE BEST CHANCE OF RAIN WILL STILL BE ALONG THE CREST OF THE BLUE RIDGE...HOWEVER...ALL PARTS OF THE FORECAST AREA WILL HAVE AT LEAST A SLIGHT CHANCE. BY SUNRISE WEDNESDAY...850 MB WINDS ARE EXPECTED TO HAVE A S-SW ORIENTATION AND HAVE INCREASED TO AROUND 45 TO 55 KTS ACROSS THE REGION AND MAINTAIN THESE SPEEDS...OR INCREASE A BIT MORE BY THE AFTERNOON. BY THE OVERNIGHT SHIFT POSTED A HIGH WIND WIND WATCH FOR THE AREA OF THE NORTHERN MOUNTAINS OF NORTH CAROLINA AND PARTS OF THE MOUNTAIN EMPIRE REGION OF SOUTHWEST VIRGINIA BASED UPON HISTORY OF WINDS OF A SIMILAR ORIENTATION AND SPEED YIELDING DAMAGING WINDS. WE ARE UPGRADING THIS WATCH TO A WARNING...AND ADJUSTING THE START AND END TIME EARLIER BY ONE HOUR TO BETTER MATCH THE HIGH WIND WARNING BY GSP. AS WEDNESDAY PROGRESSES...PRECIPITATION CHANCES WILL PROGRESSIVELY INCREASE AS THE FRONT APPROACHES...AND THEN CROSSES THE AREA DURING THE AFTERNOON. TRENDS OF THE LATEST MODEL GUIDANCE ARE ABOUT THREE HOURS SLOWER WITH THE TIMING OF THE PASSAGE. AS SUCH...HAVE ADJUSTED OUR POP AND WEATHER GRIDS ACCORDINGLY. WHEN THE FRONT MOVES THROUGH THE AREA...WE ARE EXPECTING A STRONG SQUALL LINE OF SHOWERS WITH LIMITED...IF ANY...THUNDER. THERE IS A CONCERN THAT SOME OF THE STRONGER SHOWERS COULD HELP BRING HIGHER WINDS DOWN TO THE SURFACE...AND BE POTENTIALLY DAMAGING. OUR OTHER CONCERN FROM WIND INCLUDES GRADIENT PREVAILING WINDS IN ADVANCE OF THE FRONT. DURING THE AFTERNOON AND EARLY EVENING HOURS...WIND GUSTS AT THE HIGHER PEAKS ALONG AND WEST OF THE BLUE RIDGE...MAY SEE WIND GUSTS IN EXCESS OF WIND ADVISORY CRITERIA...40 KTS. WE ARE REFLECTING THIS CONCERN IN A WIND ADVISORY THAT WILL BE IN EFFECT FROM NOON WEDNESDAY THROUGH MIDNIGHT. TEMPERATURES WILL CONTINUE TO BE ON THE MILD SIDE TONIGHT AND WEDNESDAY. LOWS TONIGHT IN THE MOUNTAINS WILL BE A MIX OF READINGS AROUND 50 TO THE LOWER 50S. EAST OF THE BLUE RIDGE...LOW TO MID 50S WILL BE COMMON. DESPITE ABUNDANT RAIN TOMORROW...WE ARE FORECASTING LOW TO MID 60 IN THE MOUNTAINS AND UPPER 60S TO LOWER 70S ACROSS THE PIEDMONT OF VIRGINIA AND NORTH CAROLINA. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... AS OF 345 PM EST TUESDAY... FRONTAL PASSAGE WEDNESDAY EVENING WILL BRING DRAMATIC CHANGE IN TEMPERATURE...READINGS FALLING FROM THE 50S/60S WEDNESDAY EVENING INTO THE 20S/30S DURING THE OVERNIGHT. SLUG OF FRONTAL PRECIP WILL MOVE RAPIDLY EAST ACROSS THE CWA DURING THE EVENING WITH DOWNPOUR OF RAIN PRODUCING UPWARDS OF AN INCH OF RAIN IN LESS THAN 2 HOURS TIME. THIS BURST OF HEAVY RAINFALL WITH THE FRONTAL PASSAGE WILL LIKELY RESULT IN SUDDEN RISES TO AREA STREAMS. WILL FORGO FLOOD WATCH ATTM PER QUICK MOVEMENT OF SYSTEM AND LACK OF SUSTAINED HEAVY RAIN THREAT. THAT SAID...STILL NOT A GOOD NIGHT TO BE FLIRTING AROUND LOW WATER CROSSINGS. FRONTAL PASSAGE HAS SLOWED A BIT COMPARED TO YESTERDAYS MODEL RUNS BY ABOUT 3 HOURS. LOOKS LIKE FROPA WILL OCCUR AT BLF/TNB BETWEEN 6-8PM...7-9PM AT BCB/ROA...AND 8-10PM AT LYH/DAN. AFTER FROPA...HEAVY RAIN THREAT WILL END...WINDS SHIFTING AROUND TO THE WEST-NORTHWEST...TEMPERATURES PLUMMETING BACK TO MORE OF A WINTER FLAVOR. ANY LINGERING MOISTURE IN THE MOUNTAINS WILL CHANGE TO SNOW SHOWERS OR FLURRIES...WITH A HALF INCH TO AN INCH OF ACCUMULATION POSSIBLE AT THE HIGHER ELEVATIONS LATE WEDENSDAY NIGHT AND EARLY THURSDAY. FOR THURSDAY AND INTO THE WEEKEND...COLD UPPER LEVEL TROUGH OF LOW PRESSURE WILL SET UP SHOP OVER THE EASTERN CONUS...ANY PRECIP PRODUCTION COMING FROM DISTURBANCES WITHIN THE NORTHERN STREAM. NEXT OPPORTUNITY FOR PRECIP FROM ONE OF THESE DISTURBANCES WILL COME THURSDAY NIGHT WITH A ROUND OF SNOW SHOWERS PASSING OVER THE MOUNTAINS AROUND MIDNIGHT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 305 PM EST TUESDAY... A LONG WAVE TROF REMAINS OVER THE EASTERN CONUS FOR THE WEEKEND. SFC HIGH CENTERED ALONG THE CAROLINA COAST SATURDAY WILL MOVE EAST INTO THE ATLANTIC OCEAN. A CLIPPER-LOW AND ATTENDING SURFACE COLD FRONT APPROACHES FROM THE WEST SATURDAY AND TRAVELS ACROSS FORECAST AREA SATURDAY NIGHT INTO SUNDAY MORNING. THE GFS SUGGEST THAT A COUPLE OF INCHES OF SNOW ACCUMULATION IS POSSIBLE IN THE WESTERN UPSLOPE AREAS. THE ECMWF HINTS AT LIGHTER SNOW TOTALS. KEPT SNOW SHOWERS IN THE NORTHWEST UPSLOPE FLOW FOR SUNDAY MORNING INTO SUNDAY AFTERNOON LEANING TOWARDS GFS THEN TAPER OFF AS THE TROF AXIS MOVES FURTHER INTO THE ATLANTIC. HIGH PRESSURE BUILDS ACROSS THE REGION SUNDAY NIGHT INTO MONDAY MORNING. ANOTHER LOW PRESSURE CENTER LIFTS NORTHEAST ACROSS GREAT LAKES AND PUSHES A COLD FRONT TOWARDS OUR REGION MONDAY. THE COLD FRONT ADVANCES ACROSS OUR REGION MONDAY NIGHT INTO TUESDAY. THE GFS DEVELOPS A LOW PRESSURE CENTER OFF THE VIRGINIA COAST MONDAY NIGHT AND LIFTS IT NORTHWARD ON TUESDAY. THE GFS SOLUTION INDICATED THAT MORE SNOW...SEVERAL INCHES ARE POSSIBLE IN THE WESTERN UPSLOPE AREAS ON MONDAY NIGHT INTO TUESDAY. WENT WITH SCATTERED POPS FOR MONDAY NIGHT INTO TUESDAY AND WILL WATCH FOR FURTHER RUNS TO SEE EVOLUTION AND DETAILS OF THIS STORM FOR EARLY NEXT WEEK. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... AS OF 635 PM EST TUESDAY... WINDS WILL HINDER AVIATION OPERATIONS LATE TONIGHT INTO WEDNESDAY. QUICKLY DETERIORATING CONDITIONS WILL ALSO BE MAJOR CONCERN. TONIGHT INTO EARLY WEDNESDAY...A COLD FRONT WILL APPROACH THE REGION FROM THE WEST. 850 MB WINDS ARE EXPECTED TO INCREASE FROM THE 200 DEGREES INTO THE 5O TO 60 KT RANGE BY LATE TONIGHT...AND 70 TO 80 KT RANGE BY THE END OF THE DAY WEDNESDAY. MOISTURE WILL BE ON THE INCREASE THROUGH THE NIGHT...WITH CIGS DEVELOPING IN THE MVFR RANGE. NEAR SURFACE WINDS WILL MAINLY BE LIGHT EXCEPT AROUND KBLF WHERE SOME GUSTINESS IS EXPECTED. OTHERWISE...AND EVEN AT KBLF...ANTICIPATE STRONG LOW LEVEL SPEED SHEAR AROUND 1000 FT AGL STARTING AROUND 06Z...1AM..TONIGHT AND CONTINUING THROUGH ABOUT 14Z...9AM...WEDNESDAY WHEN LOW LEVEL MIXING HELPS TO ALLOW FOR SOME STRONGER SURFACE GUSTS. 18Z NAM AND RAP CONTINUE TO SHOW RAIN AND MOISTURE SPREADING NORTHWARD ALONG THE SOUTHERN BLUE RIDGE TONIGHT INTO WEDNESDAY. HIGH CONFIDENCE THAT RAIN WILL FORM ACROSS THE AREA TOMORROW WITHIN THE PRE-FRONTAL TROUGH SO THAT WE EXPECT AREAS OF RAIN ALONG AND EAST OF THE CREST OF THE BLUE RIDGE BY 15Z...10AM. STRONG COLD FRONT PUSHES THROUGH THE AREA WEDNESDAY EVENING WITH HEAVY RAIN SHOWERS...QUICKLY CHANGING TO SNOW SHOWERS IN THE WEST. SHARP WIND SHIFT WITH GUSTY CONDITIONS CONTINUING. UPSLOPE SNOW SHOWERS CONTINUE BETWEEN KBLF AND KLWB THURSDAY...CLEARING EAST OF THE BLUE RIDGE. NORTHWEST FLOW WILL PREVAIL FRIDAY THROUGH SUNDAY WITH TWO POTENTIALS FOR CLIPPER SYSTEMS TO BRING UPSLOPE SNOW TO SOUTHEAST WEST VIRGINIA AND FAVORED UPSLOPE AREAS...LATE THURSDAY NIGHT IN FRIDAY AND SATURDAY NIGHT INTO SUNDAY. ANOTHER COLD FRONT IS EXPECTED TO ARRIVE MONDAY INTO MONDAY NIGHT. WHILE TIMING AND QPF OF INDIVIDUAL CLIPPER SYSTEMS REMAIN A CHALLENGE...THERE IS A GOOD CHANCE THAT ACCUMULATING SNOWS ARE POSSIBLE FOR WESTERN UPSLOPE AREAS IN THE MOUNTAINS THIS WEEKEND INTO EARLY NEXT WEEK. && .HYDROLOGY... AN INCH /1.00/ TO AND INCH AND A HALF /1.50/ OF RAIN IS ANTICIPATED WITH THE FRONTAL PASSAGE WEDNESDAY EVENING. THE BULK OF THIS RAIN WILL BE ASSOCIATED WITH A SQUALL LINE OF SHOWERS ASSOCIATED WITH A FRONTAL PASSAGE...MOST OF THIS RAIN OCCURRING IN LESS THAN 2 HOURS. DUE TO THE SHORT DURATION OF THE HEAVY RAINFALL...EXPECT RAPID RISES ALONG AREA STREAMS. AS LONG AS THE RAINFALL AMOUNTS REMAIN BELOW 1.5 INCHES...FLOODING SHOULD BE KEPT TO A MINIMUM. ENSEMBLE FORECASTS SUGGEST THERE WILL ALSO BE SOME RESPECTIBLE RISES ON THE AREA RIVERS. 1.50 INCHES OF RAIN WILL CAUSE RIVERS TO RISE TO NEAR BANKFULL. IF RAIN AMOUNTS EXCEED 1.50 INCHES OVER ANY GIVEN BASIN...THEN RIVER FLOODING WOULD BECOME AN ISSUE. ATTM...CURRENT FORECASTS REFLECT BASIN AVERAGE AMOUNTS CLOSER TO 1.25 INCHES. && .CLIMATE... RECORD HIGH TEMPERATURES AND YEAR ESTABLISHED FOR JAN 29. BLACKSBURG VA...68 IN 2013 (TIED) OLD RECORD WAS 68 IN 1975 BLUEFIELD WV....68 IN 2013 (BROKE) OLD RECORD OF 64 IN 2002 DANVILLE VA.....76 IN 2002 LYNCHBURG VA....75 IN 1975 ROANOKE VA......75 IN 1975 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WIND ADVISORY FROM NOON WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR VAZ011-013-014-016>020-022>024-032>035. HIGH WIND WARNING FROM 6 AM WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR VAZ007-009-010-012-015. NC...WIND ADVISORY FROM NOON WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR NCZ002-003-019. HIGH WIND WARNING FROM 6 AM WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR NCZ001-018. WV...WIND ADVISORY FROM NOON WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR WVZ043>045. HIGH WIND WARNING FROM 6 AM WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR WVZ042. && $$ SYNOPSIS...RAB NEAR TERM...DS SHORT TERM...PM LONG TERM...KK AVIATION...DS/KK HYDROLOGY... CLIMATE...
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
638 PM EST TUE JAN 29 2013 .SYNOPSIS... HIGH PRESSURE ALOFT WILL BUILD ACROSS THE EASTERN SEABOARD THROUGH WEDNESDAY BRINGING UNSEASONABLY WARM TEMPERATURES TO THE AREA. A STRONG COLD FRONT WILL MOVE THROUGH THE REGION LATE WEDNESDAY ACCOMPANIED BY SHOWERS WITH GUSTY WINDS AND HEAVY RAIN. MUCH COLDER TEMPERATURES WILL RETURN FOR THE END OF THE WEEK INTO THE WEEKEND AS HIGH PRESSURE MOVES SOUTHEAST FROM CANADA. THERE WILL BE SEVERAL CHANCES FOR LIGHT SNOW IN THE THURSDAY THROUGH SUNDAY PERIOD. && .NEAR TERM /THROUGH WEDNESDAY/... AS OF 300 PM EST TUESDAY... OVERNIGHT...SOUTHERLY FLOW WILL INCREASE ACROSS THE AREA IN ADVANCE OF AN APPROACHING STRONG UPPER TROUGH AND ASSOCIATED COLD FRONT. THIS WILL BRING ABUNDANT GULF OF MEXICO MOISTURE INTO THE REGION. THE RESULT WILL INCREASING..THICKENING AND LOWERING OF THE CLOUD COVER. ALL AREAS ARE EXPECTED TO BE CLOUDY BY EARLY WEDNESDAY MORNING. LIGHT PRECIPITATION WILL DEVELOP BY MIDNIGHT...PRIMARILY ALONG THE CREST OF THE BLUE RIDGE SOUTHWEST OF FLOYD VA INTO NW NC. AFTER MIDNIGHT...THE FOCUS FOR THE BEST CHANCE OF RAIN WILL STILL BE ALONG THE CREST OF THE BLUE RIDGE...HOWEVER...ALL PARTS OF THE FORECAST AREA WILL HAVE AT LEAST A SLIGHT CHANCE. BY SUNRISE WEDNESDAY...850 MB WINDS ARE EXPECTED TO HAVE A S-SW ORIENTATION AND HAVE INCREASED TO AROUND 45 TO 55 KTS ACROSS THE REGION AND MAINTAIN THESE SPEEDS...OR INCREASE A BIT MORE BY THE AFTERNOON. BY THE OVERNIGHT SHIFT POSTED A HIGH WIND WIND WATCH FOR THE AREA OF THE NORTHERN MOUNTAINS OF NORTH CAROLINA AND PARTS OF THE MOUNTAIN EMPIRE REGION OF SOUTHWEST VIRGINIA BASED UPON HISTORY OF WINDS OF A SIMILAR ORIENTATION AND SPEED YIELDING DAMAGING WINDS. WE ARE UPGRADING THIS WATCH TO A WARNING...AND ADJUSTING THE START AND END TIME EARLIER BY ONE HOUR TO BETTER MATCH THE HIGH WIND WARNING BY GSP. AS WEDNESDAY PROGRESSES...PRECIPITATION CHANCES WILL PROGRESSIVELY INCREASE AS THE FRONT APPROACHES...AND THEN CROSSES THE AREA DURING THE AFTERNOON. TRENDS OF THE LATEST MODEL GUIDANCE ARE ABOUT THREE HOURS SLOWER WITH THE TIMING OF THE PASSAGE. AS SUCH...HAVE ADJUSTED OUR POP AND WEATHER GRIDS ACCORDINGLY. WHEN THE FRONT MOVES THROUGH THE AREA...WE ARE EXPECTING A STRONG SQUALL LINE OF SHOWERS WITH LIMITED...IF ANY...THUNDER. THERE IS A CONCERN THAT SOME OF THE STRONGER SHOWERS COULD HELP BRING HIGHER WINDS DOWN TO THE SURFACE...AND BE POTENTIALLY DAMAGING. OUR OTHER CONCERN FROM WIND INCLUDES GRADIENT PREVAILING WINDS IN ADVANCE OF THE FRONT. DURING THE AFTERNOON AND EARLY EVENING HOURS...WIND GUSTS AT THE HIGHER PEAKS ALONG AND WEST OF THE BLUE RIDGE...MAY SEE WIND GUSTS IN EXCESS OF WIND ADVISORY CRITERIA...40 KTS. WE ARE REFLECTING THIS CONCERN IN A WIND ADVISORY THAT WILL BE IN EFFECT FROM NOON WEDNESDAY THROUGH MIDNIGHT. TEMPERATURES WILL CONTINUE TO BE ON THE MILD SIDE TONIGHT AND WEDNESDAY. LOWS TONIGHT IN THE MOUNTAINS WILL BE A MIX OF READINGS AROUND 50 TO THE LOWER 50S. EAST OF THE BLUE RIDGE...LOW TO MID 50S WILL BE COMMON. DESPITE ABUNDANT RAIN TOMORROW...WE ARE FORECASTING LOW TO MID 60 IN THE MOUNTAINS AND UPPER 60S TO LOWER 70S ACROSS THE PIEDMONT OF VIRGINIA AND NORTH CAROLINA. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... AS OF 345 PM EST TUESDAY... FRONTAL PASSAGE WEDNESDAY EVENING WILL BRING DRAMATIC CHANGE IN TEMPERATURE...READINGS FALLING FROM THE 50S/60S WEDNESDAY EVENING INTO THE 20S/30S DURING THE OVERNIGHT. SLUG OF FRONTAL PRECIP WILL MOVE RAPIDLY EAST ACROSS THE CWA DURING THE EVENING WITH DOWNPOUR OF RAIN PRODUCING UPWARDS OF AN INCH OF RAIN IN LESS THAN 2 HOURS TIME. THIS BURST OF HEAVY RAINFALL WITH THE FRONTAL PASSAGE WILL LIKELY RESULT IN SUDDEN RISES TO AREA STREAMS. WILL FORGO FLOOD WATCH ATTM PER QUICK MOVEMENT OF SYSTEM AND LACK OF SUSTAINED HEAVY RAIN THREAT. THAT SAID...STILL NOT A GOOD NIGHT TO BE FLIRTING AROUND LOW WATER CROSSINGS. FRONTAL PASSAGE HAS SLOWED A BIT COMPARED TO YESTERDAYS MODEL RUNS BY ABOUT 3 HOURS. LOOKS LIKE FROPA WILL OCCUR AT BLF/TNB BETWEEN 6-8PM...7-9PM AT BCB/ROA...AND 8-10PM AT LYH/DAN. AFTER FROPA...HEAVY RAIN THREAT WILL END...WINDS SHIFTING AROUND TO THE WEST-NORTHWEST...TEMPERATURES PLUMMETING BACK TO MORE OF A WINTER FLAVOR. ANY LINGERING MOISTURE IN THE MOUNTAINS WILL CHANGE TO SNOW SHOWERS OR FLURRIES...WITH A HALF INCH TO AN INCH OF ACCUMULATION POSSIBLE AT THE HIGHER ELEVATIONS LATE WEDENSDAY NIGHT AND EARLY THURSDAY. FOR THURSDAY AND INTO THE WEEKEND...COLD UPPER LEVEL TROUGH OF LOW PRESSURE WILL SET UP SHOP OVER THE EASTERN CONUS...ANY PRECIP PRODUCTION COMING FROM DISTURBANCES WITHIN THE NORTHERN STREAM. NEXT OPPORTUNITY FOR PRECIP FROM ONE OF THESE DISTURBANCES WILL COME THURSDAY NIGHT WITH A ROUND OF SNOW SHOWERS PASSING OVER THE MOUNTAINS AROUND MIDNIGHT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 305 PM EST TUESDAY... A LONG WAVE TROF REMAINS OVER THE EASTERN CONUS FOR THE WEEKEND. SFC HIGH CENTERED ALONG THE CAROLINA COAST SATURDAY WILL MOVE EAST INTO THE ATLANTIC OCEAN. A CLIPPER-LOW AND ATTENDING SURFACE COLD FRONT APPROACHES FROM THE WEST SATURDAY AND TRAVELS ACROSS FORECAST AREA SATURDAY NIGHT INTO SUNDAY MORNING. THE GFS SUGGEST THAT A COUPLE OF INCHES OF SNOW ACCUMULATION IS POSSIBLE IN THE WESTERN UPSLOPE AREAS. THE ECMWF HINTS AT LIGHTER SNOW TOTALS. KEPT SNOW SHOWERS IN THE NORTHWEST UPSLOPE FLOW FOR SUNDAY MORNING INTO SUNDAY AFTERNOON LEANING TOWARDS GFS THEN TAPER OFF AS THE TROF AXIS MOVES FURTHER INTO THE ATLANTIC. HIGH PRESSURE BUILDS ACROSS THE REGION SUNDAY NIGHT INTO MONDAY MORNING. ANOTHER LOW PRESSURE CENTER LIFTS NORTHEAST ACROSS GREAT LAKES AND PUSHES A COLD FRONT TOWARDS OUR REGION MONDAY. THE COLD FRONT ADVANCES ACROSS OUR REGION MONDAY NIGHT INTO TUESDAY. THE GFS DEVELOPS A LOW PRESSURE CENTER OFF THE VIRGINIA COAST MONDAY NIGHT AND LIFTS IT NORTHWARD ON TUESDAY. THE GFS SOLUTION INDICATED THAT MORE SNOW...SEVERAL INCHES ARE POSSIBLE IN THE WESTERN UPSLOPE AREAS ON MONDAY NIGHT INTO TUESDAY. WENT WITH SCATTERED POPS FOR MONDAY NIGHT INTO TUESDAY AND WILL WATCH FOR FURTHER RUNS TO SEE EVOLUTION AND DETAILS OF THIS STORM FOR EARLY NEXT WEEK. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... ... AS OF 635 PM EST TUESDAY... WINDS WILL HINDER AVIATION OPERATIONS LATE TONIGHT INTO WEDNESDAY. QUICKLY DETERIORATING CONDITIONS WILL ALSO BE MAJOR CONCERN. TONIGHT INTO EARLY WEDNESDAY...A COLD FRONT WILL APPROACH THE REGION FROM THE WEST. 850 MB WINDS ARE EXPECTED TO INCREASE FROM THE 200 DEGREES INTO THE 5O TO 60 KT RANGE BY LATE TONIGHT...AND 70 TO 80 KT RANGE BY THE END OF THE DAY WEDNESDAY. MOISTURE WILL BE ON THE INCREASE THROUGH THE NIGHT...WITH CIGS DEVELOPING IN THE MVFR RANGE. NEAR SURFACE WINDS WILL MAINLY BE LIGHT EXCEPT AROUND KBLF WHERE SOME GUSTINESS IS EXPECTED. OTHERWISE...AND EVEN AT KBLF...ANTICIPATE STRONG LOW LEVEL SPEED SHEAR AROUND 1000 FT AGL STARTING AROUND 06Z...1AM..TONIGHT AND CONTINUING THROUGH ABOUT 14Z...9AM...WEDNESDAY WHEN LOW LEVEL MIXING HELPS TO ALLOW FOR SOME STRONGER SURFACE GUSTS. 18Z NAM AND RAP CONTINUE TO SHOW RAIN AND MOISTURE SPREADING NORTHWARD ALONG THE SOUTHERN BLUE RIDGE TONIGHT INTO WEDNESDAY. HIGH CONFIDENCE THAT RAIN WILL FORM ACROSS THE AREA TOMORROW WITHIN THE PRE-FRONTAL TROUGH SO THAT WE EXPECT AREAS OF RAIN ALONG AND EAST OF THE CREST OF THE BLUE RIDGE BY 15Z...10AM. STRONG COLD FRONT PUSHES THROUGH THE AREA WEDNESDAY EVENING WITH HEAVY RAIN SHOWERS...QUICKLY CHANGING TO SNOW SHOWERS IN THE WEST. SHARP WIND SHIFT WITH GUSTY CONDITIONS CONTINUING. UPSLOPE SNOW SHOWERS CONTINUE BETWEEN KBLF AND KLWB THURSDAY...CLEARING EAST OF THE BLUE RIDGE. NORTHWEST FLOW WILL PREVAIL FRIDAY THROUGH SUNDAY WITH TWO POTENTIALS FOR CLIPPER SYSTEMS TO BRING UPSLOPE SNOW TO SOUTHEAST WEST VIRGINIA AND FAVORED UPSLOPE AREAS...LATE THURSDAY NIGHT IN FRIDAY AND SATURDAY NIGHT INTO SUNDAY. ANOTHER COLD FRONT IS EXPECTED TO ARRIVE MONDAY INTO MONDAY NIGHT. WHILE TIMING AND QPF OF INDIVIDUAL CLIPPER SYSTEMS REMAIN A CHALLENGE...THERE IS A GOOD CHANCE THAT ACCUMULATING SNOWS ARE POSSIBLE FOR WESTERN UPSLOPE AREAS IN THE MOUNTAINS THIS WEEKEND INTO EARLY NEXT WEEK. && .HYDROLOGY... AN INCH /1.00/ TO AND INCH AND A HALF /1.50/ OF RAIN IS ANTICIPATED WITH THE FRONTAL PASSAGE WEDNESDAY EVENING. THE BULK OF THIS RAIN WILL BE ASSOCIATED WITH A SQUALL LINE OF SHOWERS ASSOCIATED WITH A FRONTAL PASSAGE...MOST OF THIS RAIN OCCURRING IN LESS THAN 2 HOURS. DUE TO THE SHORT DURATION OF THE HEAVY RAINFALL...EXPECT RAPID RISES ALONG AREA STREAMS. AS LONG AS THE RAINFALL AMOUNTS REMAIN BELOW 1.5 INCHES...FLOODING SHOULD BE KEPT TO A MINIMUM. ENSEMBLE FORECASTS SUGGEST THERE WILL ALSO BE SOME RESPECTIBLE RISES ON THE AREA RIVERS. 1.50 INCHES OF RAIN WILL CAUSE RIVERS TO RISE TO NEAR BANKFULL. IF RAIN AMOUNTS EXCEED 1.50 INCHES OVER ANY GIVEN BASIN...THEN RIVER FLOODING WOULD BECOME AN ISSUE. ATTM...CURRENT FORECASTS REFLECT BASIN AVERAGE AMOUNTS CLOSER TO 1.25 INCHES. && .CLIMATE... RECORD HIGH TEMPERATURES AND YEAR ESTABLISHED FOR JAN 29. BLACKSBURG VA...68 IN 2013 (TIED) OLD RECORD WAS 68 IN 1975 BLUEFIELD WV....68 IN 2013 (BROKE) OLD RECORD OF 64 IN 2002 DANVILLE VA.....76 IN 2002 LYNCHBURG VA....75 IN 1975 ROANOKE VA......75 IN 1975 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WIND ADVISORY FROM NOON WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR VAZ011-013-014-016>020-022>024-032>035. HIGH WIND WARNING FROM 6 AM WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR VAZ007-009-010-012-015. NC...WIND ADVISORY FROM NOON WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR NCZ002-003-019. HIGH WIND WARNING FROM 6 AM WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR NCZ001-018. WV...WIND ADVISORY FROM NOON WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR WVZ043>045. HIGH WIND WARNING FROM 6 AM WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR WVZ042. && $$ SYNOPSIS...RAB NEAR TERM...DS SHORT TERM...PM LONG TERM...KK AVIATION...DS/KK HYDROLOGY... CLIMATE...
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1121 PM EST SUN JAN 27 2013 .SYNOPSIS... HIGH PRESSURE WILL MOVE OFFSHORE OVERNIGHT ALLOWING AN UPPER LEVEL DISTURBANCE TO CROSS THE AREA...TRIGGERING PERIODS OF RAIN AND FREEZING RAIN INTO EARLY MONDAY. UPPER LEVEL RIDGING BUILDING ACROSS THE AREA THROUGH THE EARLY PART OF THE WEEK WILL RESULT IN AN UNSEASONABLE WARMUP ACROSS THE AREA. A STRONG COLD FRONT WILL MOVE INTO THE REGION BY MID-WEEK...BRINGING WIDESPREAD MODERATE RAINFALL FOLLOWED BY A RETURN TO WINTERLIKE TEMPERATURES. && .NEAR TERM /THROUGH MONDAY/... AS OF 845 PM EST SUNDAY... SOUNDINGS CONTINUE TO SHOW QUITE A BIT OF DRY AIR BELOW 7H THIS EVENING WITH ONLY WEAK RETURN FLOW IN THE LOWEST LEVELS WHERE DEWPOINTS REMAIN IN THE 20S. PRECIP ATTEMPTING TO MOVE IN FROM THE WEST HAS CONTINUED TO WEAKEN UPON ENCOUNTERING THIS DRY POCKET AND WILL STILL TAKE SEVERAL HOURS FOR BETTER MOISTENING TO OCCUR FROM WEST TO EAST OVERNIGHT. LATEST SHORT TERM MODELS CONTINUE TO INDICATE THE MAJORITY OF THE PRECIP TO RUN ALONG AND NORTH OF HIGHWAY 460 WITH ONLY THE HRRR AT BIT MORE AGRESSIVE IN SLIDING A A SWATH OF LIGHT QPF ACROSS MOST OF THE CWA BY DAYBREAK. HOWEVER DO THINK THAT THE FAR NW COULD SEE A LITTLE MORE QPF SO UPPED ICE TOTALS A LITTLE ACROSS THE COLDER SECTIONS OF THE GREENBRIER VALLEY EAST INTO THE HIGHLANDS AND SOUTHERN SHENANDOAH VALLEY PER THE LATEST 00Z NAM. SOUTH OF THAT AREA...QUITE A BIT OF UNCERTAINTY REMAINS IN JUST HOW MUCH PRECIP WILL BE OBSERVED SINCE SEEING A NICE DRY SLOT WITH THE UPPER JET BEHIND THE INITIAL BAND NOW IN FAR SW VA WHICH COULD SPLIT THE PRECIP...PER LATEST RAP SO SOMETHING TO WATCH. HOWEVER DOES APPEAR THAT THE NW NC MOUNTAINS COULD SEE A LITTLE MORE ICE EARLY ON GIVEN CURRENT RADAR TRENDS SO BOOSTED ICE AMOUNTS THERE SLIGHTLY AS WELL. OTRW SURFACE TEMPS STILL REMAIN WELL ABOVE FREEZING WEST OF I-77 IN VIRGINIA SO WONT INCLUDE ANY ADDED CTYS OVERNIGHT. DID ADJUST POPS TO MATCH TIMING A BIT BETTER WITH ONLY SLIGHT ADJUSTS TO TEMPS AS EXPECT DEWPTS TO RISE SOME AS EVAPORATIVE COOLING DEVELOPS BEFORE ANY PRECIP ACTUALLY REACHES THE SURFACE OUTSIDE OF THE HIGHER SW RIDGES. BY LATE MORNING...TEMPERATURES ARE EXPECTED TO RISE ABOVE FREEZING AS THE WARMER AIR ALOFT WORKS ITS WAY TO THE SURFACE...ALTHOUGH DEEPER AREAS OF THE GREENBRIER VALLEY...THE SOUTHERN SHENANDOAH VALLEY...THE NEW RIVER VALLEY...AND PARTS OF THE ROANOKE VALLEY MAY TAKE A LITTLE LONGER TO WARM. MONDAY AFTERNOON TEMPERATURES ARE EXPECTED TO RISE INTO THE UPPER 40S TO THE LOW 50S FOR MOST OF THE AREA. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... AS OF 300 PM EST SUNDAY... ROLLER-COASTER WEATHER THIS PERIOD. WARMING UP TO ABOVE NORMAL TEMPS AS 5H RIDGE BUILDS OVER THE EASTERN U.S. IN ADVANCE OF A DEEPENING TROUGH OVER THE ROCKIES. THIS TROUGH PROGRESSES SLOWLY EAST TO THE PLAINS STATES TUESDAY NIGHT AND BROADENS OUT AS IT ARRIVES IN OUR AREA WEDNESDAY NIGHT. AHEAD OF THIS TROUGH SW FLOW WILL KEEP SMALL THREAT OF SHOWERS AROUND MONDAY NIGHT OVER THE NWRN CWA WITH SOME WEAK UPSLOPE. THE PATTERN...WET GROUND...AND FORECAST SOUNDINGS SUGGEST POTENTIAL FOR DENSE FOG EVENT...BUT WILL ADD AREAS OF FOG IN LATE. WINDS ARE EXPECTED TO BE UP ENOUGH WHERE SOME AREAS COULD HAVE FOG BUT NOT DENSE. MAIN IMPACT AREA SEEMS TO BE THE PIEDMONT PER THE LATEST SREF PROBABILITIES FOR VSBYS LESS THAN 1SM. ANY FOG WILL BE ERODING TUESDAY AS THIS SHOULD BE OUR WARMEST DAY...UNLESS THE FRONTAL TIMING AND PRECIP SLOW DOWN WEDNESDAY. HIGHS TUESDAY WILL BE IN THE LOWER 60S MOST LOCATIONS. COULD SEE A RECORD HIGH AT BLF AS 63F IS FORECAST AND THE RECORD IS 64 SET IN 2002. SKIES SHOULD BE PARTLY TO MOSTLY SUNNY TUESDAY. WILL SEE INCREASING DEWPOINTS AND PRECIP CHANCES HEADING INTO TUESDAY NIGHT AHEAD OF THE COLD FRONT. WINDS ARE GOING TO INCREASE AS WELL LATE OVER THE MTNS. THE LOW LVL FLOW SUGGESTS THAT THE MTN EMPIRE AREA WILL NOT BE IN THE TYPICAL FAVORED SSE FLOW FOR HIGH WINDS...BUT THIS SYSTEM APPEARS STRONG ENOUGH GIVEN MODELS PROJECTING A 50-60 KNOT JET AT 8H ARRIVING OVERHEAD BY 12Z WEDNESDAY. GIVEN SUCH STRONG WARM ADVECTION AND INCREASE IN CLOUDS WENT MILD TUESDAY NIGHT WITH LOWS IN THE 50S HIGHER ELEVATIONS...PIEDMONT AND URBAN AREAS WITH 40S ACROSS THE VALLEYS. THE SYSTEM IS VERY DYNAMIC AND WIND DRIVEN AND SPC HAS US IN AN OUTLOOK FOR POTENTIAL SEVERE WEATHER WEDNESDAY. ON THE SIDE FAVORING SEVERE IS THE WIND ENERGY WITH 70+ KNOT LLJ MOVING FROM TN/OH VALLEY WED MORNING TO DELMARVA AT 18Z WED...WITH SECONDARY WIND MAX PUSHING FROM UPSTATE SC TO ERN VA IN THE AFTERNOON. SHEAR IS TOP OF THE CHARTS PER HODOGRAPHS. CONDITIONS INHIBITING SVR ARE WEAK LAPSE RATES...LOTS OF CLOUDS/RAIN AND LITTLE IF ANY CAPE. HOWEVER...CONFIDENT THAT THIS WILL BE A CASE WHERE SOME OF THE SHOWERS ALONG THE FRONT BRING DOWN GUSTS OVER 50 MPH OR MORE...SIMILAR TO SOME OF THE EVENTS WE GET IN LATE FEB- MARCH...WHERE THUNDER IS LIMITED. ADDED THUNDER AND GUSTY WINDS FOR NOW TO THE FORECAST IN THE MTN EMPIRE/SE WV INTO NW NC BY MIDDAY WEDNESDAY AND OUT EAST IN THE AFTN. THE 12Z ECMWF HAS COME IN SLOWER WITH THE FRONT AND THIS MAY BE THE CASE GIVEN THE AMPLIFIED PATTERN. THIS MAY NEED TO ADJUSTED LATER SHIFTS...AS FOR NOW WILL HAVE THE HIGHEST THREAT OF RAIN IN THE LATE MORNING TO AFTN TIME FRAME...EXITING WED NIGHT. THIS WILL AFFECT HIGHS SOMEWHAT BUT KEPT IN THE PIEDMONT WARM WITH TEMPS IN THE MID 60S WITH MID 50S TO NEAR 60 WEST. STRONG COLD AIR ADVECTION PUSHES IN WED NIGHT AS 8H TEMPS CRASH FROM +10C WED AFTN TO -5 TO -8C LATE WED NIGHT. MOISTURE STAYS IN THE WRN COUNTIES THROUGH THE NIGHT WHERE RAIN CHANGES TO SNOW SHOWERS. WILL MORE THAN LIKELY SEE SOME WIND ADVISORY CRITERIA...ALTHOUGH MODELS ONLY SHOW 35-40 KTS AT 8H. TEMPS WED NIGHT SHOULD DROP INTO THE MID 20S WEST TO UPPER 30S EAST...ALTHOUGH MAY STAY WARMER IF SYSTEM SLOWS DOWN AND THE CLOUDS/WIND DESPITE THE CAA KEEP TEMPS MORE ELEVATED LONGER. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 300 PM EST SUNDAY... COLD FRONT WILL CONTINUE TO MARCH EAST INTO THE ATLANTIC OCEAN THURSDAY. STRONG CAA BEHIND THE FRONT WILL RESULT IN TEMPERATURES THURSDAY SIGNIFICANTLY COLDER THAN WEDNESDAY...WITH READINGS FROM AROUND 30 DEGREES IN THE NORTHWEST TO THE UPPER 40S IN THE SOUTHEAST. GUSTY NORTHWEST WINDS IN THE WAKE OF THE COLD FRONT WILL RESULT IN RAIN AND SNOW SHOWERS CHANGING TO SNOW SHOWERS AND SNOW FLURRIES. ANOTHER REINFORCING SHOT OF COLD AIR SHOULD ARRIVE THURSDAY NIGHT INTO FRIDAY. THE SHORTWAVE ROTATING AROUND THE TROUGH LOOKED MORE ROBUST ON ECMWF THAN THE GFS. LOW TEMPERATURES THURSDAY NIGHT WILL BE SEASONABLY COLD WITH VALUES FROM THE TEENS IN THE NORTHWEST MOUNTAINS TO THE MID 20S IN THE SOUTHEAST. FRIDAY INTO FRIDAY NIGHT...ANTICIPATE THAT SNOW SHOWERS WILL TAPER OFF OR END AS HIGH PRESSURE BUILDS IN FROM THE WEST. KEEP YOUR WINTER COATS READY ON FRIDAY WITH HIGHS FROM THE LOWER 20S IN THE NORTHWEST TO AROUND 40 IN THE SOUTHEAST. THE HIGH CENTER BUILDS OVERHEAD FRIDAY NIGHT INTO SATURDAY MORNING. FRIDAY NIGHT LOWS WILL VARY FROM THE SINGLE DIGITS TO THE LOWER 20S IN THE SOUTH. THE HIGH CENTER MARCHES EAST TO THE CAROLINA COAST ON SATURDAY...ALLOWING ANOTHER COLD FRONT TO APPROACH FROM THE WEST. THE COLD FRONT TRAVELS EAST AND REACHES THE MOUNTAINS SATURDAY NIGHT INTO SUNDAY MORNING. AS THE TROF AXIS MOVES INTO THE ATLANTIC...HIGH PRESSURE SETTLES OVER THE SOUTHEAST ON SUNDAY. && .AVIATION /04Z MONDAY THROUGH FRIDAY/... AS OF 1105 PM EST SUNDAY... DRY AIR SLOWLY GIVING WAY FROM WEST TO EAST ATTM AS THE INITIAL BATCH OF -RA/-FZRA MOVES ACROSS THE WESTERN MOUNTAINS AND SHOULD ARRIVE ALONG THE BLUE RIDGE SHORTLY AFTER MIDNIGHT. THIS BAND OF PRECIP SHOULD FINALLY MOISTEN THE COLUMN ENOUGH TO ALLOW CIGS TO LOWER TO LOW END VFR OR HIGH MVFR LEVELS FROM WEST TO EAST DURING THE NEXT FEW HOURS. PRECIP INITIALLY IN THE FORM OF -RA WILL IMPACT KBLF IN THE NEXT HOUR AND THEN LIKELY SWITCH TO A MIX OF -RA/-FZRA AS SURFACE TEMPS COOL. THE LIGHT MIX SHOULD ALSO WORK INTO THE KLWB VICINITY BETWEEN MIDNIGHT AND 1 AM RESULTING IN PERIODS OF -FZRA INTO THE PREDAWN HOURS OF MONDAY. OTRW THE UPSTREAM WARM FRONT WILL SLIDE BY TO THE NW OVERNIGHT WITH LIGHT PRECIP ARCING FAR ENOUGH SE TO CLIP MUCH OF THE REST OF THE REGION OVERNIGHT. ASSOCIATED PTYPE LOOKS TO BE MAINLY FREEZING RAIN THOUGH QPF AMOUNTS SHOULD BE RELATIVELY LIGHT. KDAN APPEARS TO BE ON THE SOUTHERN EXTENT OF THE PRECIP AND MAY MISS OUT ON SEEING MUCH AT ALL. ELSW STILL EXPECTING A PERIOD OF LIGHT MIX ROUGHLY IN THE 05Z TO 13Z TIME FRAME WITH THE MAJORITY SWINGING THROUGH THE KLWB VICINITY...WITH LESS SOUTH OF A KLYH- KROA- KBCB LINE EARLY MONDAY. EXPECT TEMPS MAY NUDGE UP JUST ENOUGH ABOVE FREEZING TO CAUSE LOCATIONS SUCH AS KBLF TO SWITCH BACK TO JUST RAIN BEFORE TAPERING MID MORNING MONDAY AS WELL. OTRW KEEPING IT MAINLY -FZRA FOR NOW. CIGS AND VSBYS SHOULD ALSO BE LOWEST ACROSS THE NORTH WHERE MOISTURE WILL BE DEEPER SO CANT RULE OUT A PERIOD OF IFR AT KLWB...WHILE EXPECTING A PERIOD OF MOSTLY MVFR LEVEL CLOUD BASES ELSW FOR NOW INTO MONDAY MORNING. SHOULD SEE CONDITIONS IMPROVE BEHIND THE EXITING PRECIP MIDDAY MONDAY BEFORE CIGS LOWER AGAIN IN THE AFTERNOON WITH MOISTURE AND WEAK IMPULSES SLIDING AROUND THE DEVELOPING UPPER RIDGE. THIS COULD RESULT IN ANOTHER PERIOD OF -RA/-SHRA AT BOTH KBLF/KLWB MONDAY AFTERNOON. DESPITE INCREASING SW FLOW APPEARS LOW LEVEL MOISTURE WILL BE SLOW TO EXIT MONDAY NIGHT WITH THE POTENTIAL FOR IFR IN LOW CIGS AND PERHAPS A FEW LEFTOVER -SHRA MAINLY SE WVA SITES MONDAY EVENING. DRYING CONDITIONS CAN BE EXPECTED TUESDAY AND WILL SEE A BRIEF PERIOD OF IMPROVED FLYING WEATHER AHEAD OF A STRONG COLD FRONT INTO TUESDAY NIGHT...WITH VFR/MVFR EXPECTED UNTIL THE FRONT AND ITS ASSOCIATED PRECIP SHIELD ARRIVES WEDNESDAY. THIS FRONT MAY BRING PERIODS OF MODERATE TO HEAVY RAIN ALONG WITH AN ISOLATED THUNDERSTORM AND GUSTY WINDS TO PARTS OF THE REGION MIDWEEK. THIS FRONT WILL BE FOLLOWED BY ANOTHER SHOT COLD AIR INCLUDING WINDY CONDITIONS AND UPSLOPE MVFR CIGS WITH -SHSN AT KBLF/KLWB WEDNESDAY NIGHT INTO THURSDAY. ANOTHER FAST MOVING WEAK DISTURBANCE MAY BRING THE NEXT ROUND OF MAINLY MOUNTAIN -SHSN ALONG WITH MVFR CIGS ON FRIDAY. DUE TO THE MISSING OBSERVATION FROM KBCB...INCLUDING AMD NOT SKED FOR THE TAF FORECAST THERE GIVEN UNCERTAINTY IN UPCOMING CIGS AND VSBYS AS PRECIP ARRIVES OVERNIGHT. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...FREEZING RAIN ADVISORY UNTIL 10 AM EST MONDAY FOR VAZ010>020- 022>024-032>035-043>047-058-059. NC...FREEZING RAIN ADVISORY UNTIL 10 AM EST MONDAY FOR NCZ001>006- 018>020. WV...FREEZING RAIN ADVISORY UNTIL 10 AM EST MONDAY FOR WVZ042>045. && $$ SYNOPSIS...NF NEAR TERM...JH/NF SHORT TERM...WP LONG TERM...KK AVIATION...JH/MBS/NF
AREA FORECAST DISCUSSION
NWS SPOKANE WA
254 PM PST Tue Jan 29 2013 .SYNOPSIS... The weather pattern will remain active and wintry through Thursday as a number of storm systems will result in periodic heavy snow accumulations...another extended snow event looks likely for the region with the focus of the heavier snow again for the higher terrain of the Central Idaho Panhandle...the Blue mountains and the Camas Prairie. High pressure will build into the region at the end of the work week and linger into the weekend with fog and low stratus expected across much of the basin and in the valleys. && .DISCUSSION... ...ANOTHER ROUND OF MODERATE TO LOCALLY HEAVY SNOW EXPECTED TONIGHT INTO EARLY WEDNESDAY ACROSS PORTIONS OF THE CENTRAL IDAHO PANHANDLE AND EXTREME SOUTHEAST WASHINGTON... Tonight through Wednesday...Winter weather system number three will be the main focus during this period. This is the latest system to ride down into the Inland NW via swift northwest flow aloft. This system will be the most moisture laden of the three and thus will likely produce the greatest amounts of precipitation. However unlike the last couple systems...this one should be the warmest as well...so snowfall totals and snow ratios will likely under-perform the previous events. Looking at the latest water vapor satellite pictures there was a well defined plume of moisture wrapping over the top of the ridge and pushing into the southern third of British Columbia. This plume is expected to shift southeast overnight as it encroaches on the eastern flank of the strong eastern Pacific ridge axis. As the moisture tracks into the forecast area we should see increasing clouds and a rapid increase in precipitation. Just like last night...the bulk of the precipitation will focus over the SE corner of Washington and the central Idaho Panhandle. For these locations we have forecast anywhere from 0.25-0.50 inches of precipitation. If snow levels were close to what they have been over the past few nights...we`d be looking at widespread snowfall reports of 3-7 inches across portions of the Camas Prairie...Idaho Palouse...Blue Mountains...and central Idaho Panhandle Mountains with locally heavier amounts possible over NW facing slopes. However...temperatures are considerably warmer than they have been. Down on the Palouse and Lewiston area...the 24 hour departure is about 5 degrees warmer. This wouldn`t be important if we had dry air entrenched in the lower atmosphere, but that`s not the case...as wet-bulb temperatures in that region were generally right around freezing on the Palouse...and in the mid 30s around Lewiston. That will prove critical...as we won`t see a lot of cooling this evening with the skies clouding up so rapidly. Also SW winds will be increasing through the boundary layer up to 850 mbs which should keep the wet-bulb temperatures steady if not cause them to slowly rise. Thus we expect a much smaller area to be impacted by the significant snows tonight into Wednesday morning. We have decided to issue another batch of winter weather highlights with advisories for the Idaho Palouse (mainly above 2500-3000 ft), the Camas Prairie (also above 3000 ft), and Blue Mountains (above 4000 ft). Snow amounts will range from 2-5" on the Idaho Palouse...3-7" on the Camas Prairie and locally heavier amounts over the Blue Mountains. As for valley locations...the southern half of the central Idaho Panhandle should receive the heaviest snow amounts. Locations such as Deary...Bovill...Clarkia could see amounts ranging from 4-7" and for this reason we will issue a winter storm warning. Some of this snow should be blown about by moderate westerly winds at least over exposed locations. For the remainder of the forecast area...the event will be a rather minor one as swift moving NW flow systems generally underwhelm from a precipitation standpoint, especially when considering there is nary a significant surface or 850 mb low. And this should be the case once again. So although locations across the eastern Columbia Basin...Spokane area...NE Washington and the north Idaho Panhandle should see some snow...amounts should be rather light and unimpressive. fx Wednesday night through Friday night...Long-wave ridge axis remains placed off the coast which continues to favor a flow from the northwest for storm system to utilize until Friday. Any disturbances that drop down the east edge of this long-wave ridge orienting the northwest flow gets its moisture tap weakened by passing through the long-wave ridge itself limiting moisture availability. There is not much instability to work nor is there any significant cold air damming in most of the lowlands as well so with all these things in mind pops and QPF will remain marginal and favor the extreme western edge of the Cascade Crest along with extreme Northeast Washington and the Northern Idaho Panhandle. Remaining locations especially those in the lowlands such as the Columbia Basin and vicinity will have substantially lower pops with low to no QPF mention for much of this interval as well. Storm track interrupted with Shortwave ridging for Friday night allows for a dry forecast with perhaps some inversions developing as the low level flow favors a warmer trajectory from the southwest. Perhaps this may be a night suitable for fog and low cloud formation for lowlands and valleys. Forecast temperatures show a loose warming trend in daytime highs but overnight lows will be noisy as disturbance passage from northwest brings cooler air-mass down and shortwave ridging Friday night allows for inversions which may allow for warmer mid-slope temperatures compared to lowlands and valleys and this would just as loosely translate to snow levels as well. /Pelatti Saturday through Tuesday: High confidence in a high pressure ridge to build in over the region this weekend. The ridge will result in weak winds and large scale subsidence with widespread stratus and patchy fog across the region. Boundary layer winds will be out of the east down the Palouse on Saturday. Fog and stratus will more likely burn off across this area and will be pushed up against the northern mountains of eastern WA and up against the east slopes of the Cascades. Models are in good agreement with a weakening shortwave pushing in to this ridge Saturday night into Sunday. This wave looks to split apart with the bulk of the energy diving southward and forming a closed low off of the southern California coastline and Baja California. The northern branch of this trough will quickly push across the region, but models are not showing much dynamics after it splits and does not look to play a big factor in our weather. Models become more uncertain after this period as far as when the ridge will actually break down. The operational runs of the GFS and the ECMWF are in fairly good agreement with each other in showing the ridge re-amplifying after the passage of the weak wave on Sunday. 500 mb pressure patterns continue to show an amplifying pattern over the west coast as low pressure in the Gulf of Alaska digs down the western coastline. This would result in a slower break down of the ridge over the area. The Canadian model shows a flatter ridge or more moist zonal flow pattern heading into early next week. The GEFS ensemble mean is more reflective of a quicker break down of the ridge. However, there is a large spread in the individual ensemble members of the GEFS. Due to this uncertainty, I did not make much in the way of changes to the forecast, which follows a slower break down of the ridge more toward Tuesday and Tuesday night. I did keep a mention of the possibility of precipitation in the mountains for Sunday through Monday night with the GEFS ensemble mean showing a fast break down of the ridge. We will be on the warm side of the jet stream with 850 mb winds out of the southwest. The southwest orientation will likely advect up warmer temperatures, so snow levels are expected to be above valley floors when the first wave of moisture moves through. Temperatures this weekend will have little diurnal variability across the western basin and in the surrounding valleys where stratus is most likely. There is more uncertainty with stratus coverage in early next week and temperatures will be dependent on this cloud cover; however, I generally went with warming daytime temperatures with warm air advection at low to mid levels. /SVH && .AVIATION... 18Z TAFS: main trouble spots this morning are along the KGEG-KCOE corridor due to areas of stratus and IFR cigs. Feel confident that these should be mainly gone before 20-21z...with VFR conditions after that. All remaining sites should be VFR through the daytime hours. For tonight...the next winter system will come into play. The latest HRRR has delayed the onset of the pcpn until aft 04z for all sites xcp MWH and EAT. Feel confident that the pcpn will be -sn for all sites xcp LWS and that IFR conditions will ensue shortly after the onset of pcpn. Looks like the eastern sites should see abt 6hrs of pcpn...aft which the main concern will be widespread stratus and fog. MOS guidance is suggesting IFR conditions for all the eastern sites and we have generally followed suit. fx && .PRELIMINARY POINT TEMPS/POPS... Spokane 29 38 30 36 27 36 / 70 20 30 40 20 10 Coeur d`Alene 29 38 31 36 28 36 / 70 30 50 70 40 20 Pullman 32 38 33 39 30 38 / 90 60 70 60 30 10 Lewiston 37 47 37 46 33 45 / 90 50 70 60 30 10 Colville 27 37 30 41 27 40 / 70 20 20 30 30 10 Sandpoint 29 36 28 36 28 36 / 70 40 60 70 60 20 Kellogg 28 36 30 39 29 38 / 100 90 80 80 70 50 Moses Lake 29 41 29 41 27 40 / 20 10 10 10 10 10 Wenatchee 30 38 29 39 27 39 / 10 0 10 10 10 10 Omak 25 35 24 36 25 35 / 40 10 10 10 10 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Winter Weather Advisory from 7 PM this evening to 10 AM PST Wednesday for Idaho Palouse. Winter Storm Warning from 7 PM this evening to Noon PST Wednesday for Central Panhandle Mountains. Winter Weather Advisory from 7 PM this evening to 10 AM PST Wednesday for Lewis and Southern Nez Perce Counties. WA...Winter Weather Advisory from 7 PM this evening to 10 AM PST Wednesday for Northeast Blue Mountains. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1200 PM CST MON JAN 28 2013 .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT 344 AM CST MON JAN 28 2013 NUMEROUS FORECAST CONCERNS: 1. DENSE FOG THIS MORNING 2. TEMPERATURES THROUGH TUESDAY 3. POTENTIAL FOR FREEZING RAIN/DRIZZLE TONIGHT 4. POTENTIAL FOR MORE DENSE FOG TONIGHT. 5. THUNDERSTORM POTENTIAL TONIGHT/TUESDAY 6. POSSIBLY ANOTHER INTERESTING SYSTEM FOR TUESDAY NIGHT/WEDNESDAY CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING OVER THE WESTERN U.S....RIDGING OVER THE EASTERN TWO THIRDS OF THE U.S....WITH A SHORTWAVE TOPPING THIS RIDGING STRETCHED ACROSS WESTERN WI. THIS SHORTWAVE WAS THE ONE RESPONSIBLE FOR BRINGING MUCH OF THE WINTRY PRECIPITATION YESTERDAY TO THE FORECAST AREA. THIS PRECIPITATION HAS NOW SHIFTED NORTH INTO UPPER MICHIGAN. STILL DEALING WITH SOME DRIZZLE/FREEZING DRIZZLE...BUT MUCH OF THIS HAS MOVED OFF TO THE EAST INTO EASTERN WISCONSIN. PLENTY OF LOW CLOUDS REMAIN DUE TO TRAPPED LOW LEVEL MOISTURE BELOW A SUBSIDENCE INVERSION PRODUCED BY THE SHORTWAVE. 00Z DVN AND OAX SOUNDINGS ARE MOST REPRESENTATIVE OF THIS TRAPPED LOW LEVEL MOISTURE. THE RECENT PRECIPITATION INTO THE COOL AIRMASS THAT PRE-EXISTED THE PRECIPITATION...COMBINED WITH A WEAKENING PRESSURE GRADIENT ASSOCIATED WITH A SURFACE LOW NOW IN NORTHEAST IOWA...HAS RESULTED IN AN EXPANSION OF DENSE FOG FROM OMAHA NE NORTHEAST INTO THE SOUTHERN HALF OF THE FORECAST AREA. SOUTH OF THIS LOW PRESSURE AREA...TEMPERATURES CLIMB WELL INTO THE 30S AND EVEN UPPER 40S ACROSS SOUTHERN IOWA. FARTHER SOUTH...TEMPERATURES AND DEWPOINTS ARE IN THE 50S ACROSS MISSOURI. NORTH OF THE LOW...TEMPERATURES ARE HOLDING NEAR OR JUST BELOW FREEZING. OTHER NOTES...A LARGE AREA OF DRY AIR IS NOTED FROM NORTHERN MEXICO INTO THE FORECAST AREA ON WATER VAPOR. DESPITE THIS UPPER LEVEL DRY AIR...00Z PRECIPITABLE WATER PLOT FROM SOUNDINGS SHOWED 0.7-1.1 INCH READINGS FROM THE TEXAS GULF COAST NORTH TO THE FORECAST AREA...ANYWHERE FROM 200-330 PERCENT OF NORMAL. TO THE WEST...LOW PRESSURE HAS BEEN FORMING OVER NORTHEAST COLORADO DOWNSTREAM OF THE WESTERN TROUGH. PRETTY POTENT SHORTWAVE TOO AT THE BASE OF THE TROUGH IN SOUTHERN CALIFORNIA. TODAY...MUCH OF THE DAY WILL FEATURE SUBSIDENCE IN THE WAKE OF THE SHORTWAVE THAT BROUGHT THE WINTRY MIX YESTERDAY. HIGH PRESSURE SHOULD BUILD IN TOO IN THE WAKE OF THE SURFACE LOW CURRENTLY IN NORTHEAST IOWA. THUS...ANTICIPATING A DRY DAY. THERE ARE A COUPLE FORECAST ISSUES...THOUGH. FIRST IS THE CLOUDS. THERE ARE SOME HINTS IN THE 28.00Z NAM/GFS SOUNDINGS THAT THE CLOUDS MAY TRY TO BREAK UP SOMEWHAT DURING THE AFTERNOON. THE CAUSE IS A COMBINATION OF PERSISTENT DEEP LAYER SUBSIDENCE AND DIURNAL MIXING. ALTHOUGH LIGHT WINDS ARE A PROBLEM FOR MIXING OUT THE CLOUDS...FEEL THE AFOREMENTIONED TWO REASONS SOUND REASONABLE TO MENTION SOME CLEARING IN THE FORECAST. THIS PARTIAL CLEARING COMBINED WITH 925MB TEMPS PROGGED AT 18Z IN THE -2C NORTH TO +2C SOUTH SHOULD ALLOW TEMPERATURES TO CLIMB INTO THE MID 30S NORTH TO LOW 40S SOUTH. THE NEXT CONCERN IS THE MORNING FOG. HAVE ISSUED A DENSE FOG ADVISORY TO COVER THE LIGHT WINDS AND RECENT MOISTURE...VALID TIL NOON. IT MAY BE EXPANDED FURTHER NORTHEAST. ASSUMING THE BREAKS IN THE CLOUDS DEVELOP AS PLANNED...THE DENSE FOG ADVISORY END TIME OF NOON SHOULD WORK OUT. TONIGHT...MODELS ALL SHOW THAT THE POTENT SHORTWAVE IN SOUTHERN CALIFORNIA IS GOING TO EJECT NORTHEASTWARD DURING THIS PERIOD...IN RESPONSE TO YET ANOTHER SHORTWAVE IN NORTH CALIFORNIA THAT DROPS SOUTH THROUGH THE STATE. AS THE POTENT SHORTWAVE LIFTS NORTHEAST TO ABOUT EASTERN SOUTH DAKOTA BY 12Z TUESDAY...IT BRINGS AND DEEPENS THE SURFACE LOW WITH IT. MODELS HAVE TRENDED WEST WITH BOTH FEATURES...WITH THE LOW NOW REACHING NEAR MASON CITY BY 12Z TUESDAY. A MORE WESTWARD TRACK MEANS A COUPLE OF THINGS: 1. MORE WARM AIR WILL SPREAD ALOFT OVER THE FORECAST AREA. IN FACT...MAX TEMPERATURES ALOFT ARE NOW INDICATED BETWEEN 6-14C... WHICH IS PLENTY WARM ENOUGH TO KEEP THE PRECIP IN A LIQUID FORM IN THE AIR. IN ADDITION...THERE ARE NO INDICATIONS OF ICE IN THE CLOUDS THROUGHOUT THE NIGHT...ALSO SUPPORTING LIQUID. THUS...SURFACE TEMPERATURES WILL DETERMINE WHETHER ANY FREEZING OCCURS. THE PARTIAL CLEARING THAT DEVELOPS THIS AFTERNOON MAY ALLOW TEMPERATURES TO BRIEFLY DIP BELOW FREEZING THIS EVENING...BEFORE WARM ADVECTION KICKS IN AND BRINGS TEMPS UP. IN FACT...THE WARMING IS PRETTY IMPRESSIVE...WITH BOTH THE 28.00Z CANADIAN AND 27.12Z ECMWF BRINGING 50S INTO THE SOUTHEASTERN THIRD OF THE FORECAST AREA. 2. PRECIPITATION CHANCES. AS THE LOW LIFTS NORTHEAST...925-850MB MOISTURE TRANSPORT AND 285-295K LIFT INCREASE SOUTHWEST TO NORTHEAST ACROSS THE FORECAST AREA DURING THE EVENING. ALL MODELS HINT THAT THIS WILL RESULT IN NOT ONLY CLOUDS RE-FORMING...BUT ALSO THE DEVELOPMENT OF DRIZZLE. SINCE MUCH OF THE AREA COULD SEE A FEW HUNDREDTHS...DRAMATICALLY INCREASED PRECIPITATION CHANCES. ALSO INCREASED PRECIPITATION CHANCES FOR ITEM NUMBER 3 BELOW. 3. SHOWER/THUNDERSTORM POTENTIAL. THERE ARE INDICATIONS AFTER MIDNIGHT IN THE SOUTHEASTERN HALF OF THE AREA OF SOME SHOWERS DEVELOPING. THE 28.00Z NAM HAS UPWARDS OF 500 J/KG OF CAPE LIFTED FROM 900MB NEAR BOSCOBEL AT 09Z. THIS CAPE WAS NOTED YESTERDAY...BUT OFF TO THE EAST OF US GIVEN THE FARTHER EAST LOW TRACK AT THE TIME. NOW THAT THE LOW TRACK IS FARTHER WEST...THE INSTABILITY SHIFTS A BIT WEST. THE 28.00Z UKMET/ECMWF ALSO HINT AT THE INSTABILITY... MORESO THAN THE 28.00Z GFS. IN ANY EVENT...ADDED A CHANCE OF THUNDERSTORMS IN THE SOUTHEAST HALF OF THE AREA AFTER MIDNIGHT. PROMISING SCENARIO FOR THUNDERSTORMS TOO WITH THE CAPE GETTING INGESTED INTO THE LOW LEVEL FRONTOGENESIS CIRCULATION. CANNOT RULE OUT SOME SMALL HAIL TOO GIVEN THE FORCING...CAPE AND FREEZING LEVELS AROUND 8000 FT. ALSO TO NOTE IS THAT PRECIPITABLE WATER VALUES ARE AROUND 4 STANDARD DEVIATIONS ABOVE NORMAL AT 12Z TUESDAY...OR AROUND 1 INCH. 4. FOG...THE PARTIAL CLEARING IN THE EVENING COMBINED WITH MOISTURE COMING BACK IN IS FAVORABLE FOR FOG FORMATION. A DENSE FOG ADVISORY WILL LIKELY BE NEEDED AGAIN. THE FOG MAY TRY TO CLEAR OUT AS WARM AIR APPROACHES...BUT AT THE SAME TIME DEWPOINTS ARE RISING. TUESDAY...THE SHORTWAVE OVER EASTERN SOUTH DAKOTA AT 12Z IS PROGGED TO LIFT UP INTO NORTHWEST ONTARIO...BRINGING THE SURFACE LOW THROUGH EAU CLAIRE WI AND INTO EASTERN LAKE SUPERIOR AROUND 00Z WEDNESDAY. IT APPEARS THAT THE COLD FRONT ASSOCIATED WITH THIS LOW WILL END UP CROSSING THE FORECAST AREA WEST TO EAST THROUGH THE DAY. THIS MEANS HIGHS COULD VARY GREATLY ACROSS THE FORECAST AREA WEST TO EAST...AND THAT WE SHOULD SEE A FALLING TEMPERATURE CURVE...ESPECIALLY DURING THE AFTERNOON. DRAMATICALLY INCREASED HIGH TEMPERATURES WITH THE FARTHER WEST TRACK...TOWARDS THE 28.00Z ECMWF. THE 28.00Z REGIONAL CANADIAN IS REALLY IMPRESSIVE...A 63F HIGH FOR THE PLATTEVILLE AREA. DID NOT GO THAT HIGH...BUT SOMETHING TO WATCH. REGARDING PRECIPITATION...MAY STILL BE DEALING WITH SOME LIGHT DRIZZLE IN THE MORNING FOR MOST LOCATIONS...THEN DRY ADVECTION COMES IN BEHIND THE COLD FRONT TO END THE PRECIPITATION FOR THE AFTERNOON. WE WILL HAVE TO WATCH THE COLD FRONT AND FRONTOGENESIS ALONG IT. IN THE CASE OF THE 28.00Z NAM/ECMWF...THEY STILL HAVE SOME SHOWER/THUNDERSTORM POTENTIAL IN THE MORNING BEFORE THE FRONT PUSHES EAST. THUS...HAVE INCLUDED SHOWER AND THUNDERSTORMS IN THE MORNING. TUESDAY NIGHT INTO WEDNESDAY...THINGS MAY GET INTERESTING AGAIN. ALL MODELS INDICATE THAT THE SHORTWAVE DIGGING THROUGH CALIFORNIA THROUGH TONIGHT STRENGTHENS AS IT REACHES THE BASE OF THE TROUGH. IN THE CASE OF THE 28.00Z GFS/UKMET...THEY BRING THIS INTENSIFYING SHORTWAVE NORTHEAST THROUGH THE PLAINS...DEEPENING A SURFACE LOW ALONG THE TRAILING COLD FRONT FROM TUESDAYS SYSTEM. SHOULD THIS SCENARIO PLAY OUT...WE WOULD BE LOOKING AT A DEFORMATION BAND OF ACCUMULATING SNOW IMPACTING THE AREA AFTER MIDNIGHT TUESDAY MORNING THROUGH AT LEAST MID-DAY WEDNESDAY. BLOWING SNOW WOULD ACCOMPANY IT AS WELL GIVEN INTENSIFYING WINDS. ON THE OTHER HAND...THE 28.00Z ECMWF/CANADIAN/NAM KEEP THIS INTENSIFYING SHORTWAVE TRACKING MORE EAST-NORTHEAST...CALL IT MORE OF A POSITIVE TILT VERSUS A NEUTRAL TILT OF THE GFS/UKMET. THESE MODELS ALSO HAVE THE LOW DEVELOPING ON THE FRONT...BUT BECAUSE OF THE SHORTWAVE TRACK/TILT...THERE REALLY IS NO DEFORMATION BAND AND OUR AREA ENDS UP DRY. SINCE THERE ARE TWO PLAUSIBLE SITUATIONS...WILL TRY TO COMPROMISE AND HAVE 20 PERCENT CHANCES OF SNOW IN FOR BOTH TUESDAY NIGHT AND WEDNESDAY. THIS PERIOD REMAINS HIGHLY UNCERTAIN AND REALLY NEEDS TO BE WATCHED. BOTH SCENARIOS WOULD END UP HAVING COLD ADVECTION AND INCREASING WINDS. IN FACT...TEMPERATURES SHOULD JUST KEEP ON FALLING. WENT WITH A BLEND OF GUIDANCE FOR HIGHS AND LOWS. WEDNESDAY NIGHT...WHETHER A SYSTEM IMPACTS THE AREA ON WEDNESDAY OR NOT...MODELS ARE IN GOOD AGREEMENT ON A DRY FORECAST AS THE AREA LIES IN SUBSIDENCE BUT STILL GENERAL UPPER TROUGHING ALOFT. THERE WILL BE A POTENT SHORTWAVE APPROACHING THE AREA FROM THE NORTHWEST...DROPPING INTO MN BY 12Z. THIS SHORTWAVE IS CURRENTLY UP IN THE YUKON TERRITORY...THUS EXPECT A SURGE OF ARCTIC AIR WITH IT. BY 12Z THURSDAY...THE 850MB TEMPS ARE PROGGED TO FALL TO -16 TO -20C OVER THE AREA...WITH -24C READINGS LURKING UP AROUND FARGO. THIS CONTINUED COLD AIR ADVECTING IN WILL HELP SEND LOWS DOWN INTO THE 5 BELOW TO 5 ABOVE RANGE. .LONG TERM...THURSDAY THROUGH SUNDAY NIGHT 344 AM CST MON JAN 28 2013 28.00Z ECMWF/GFS/CANADIAN AND ECMWF ENSEMBLES ARE IN REALLY GOOD AGREEMENT WITH THE UPPER LEVEL AND EVEN SURFACE PATTERNS THROUGH THE LONG TERM PERIOD. DEEP TROUGHING IS PROGGED OVER THE EASTERN TWO THIRDS OF CANADA DOWN INTO OUR AREA AND THE GREAT LAKES REGION FOR THURSDAY INTO FRIDAY...AIDED BY THAT POTENT SHORTWAVE DROPPING INTO MN AT 12Z THURSDAY. THOSE COLD 850MB TEMPS NEAR FARGO ND SLIDE INTO THE AREA ON THURSDAY...SETTING THE STAGE FOR A CHILLY THURSDAY NIGHT. ARCTIC HIGH PRESSURE LOOKS TO DROP INTO WESTERN IOWA BY 12Z FRIDAY...SO THERE IS GOING TO BE A NORTHWESTERLY BREEZE THE ENTIRE TIME FROM THURSDAY INTO THURSDAY NIGHT. THUS...EXPECT WIND CHILLS TO BE AN ISSUE. ADVISORIES STILL LOOK LIKELY FOR THURSDAY MORNING AND THURSDAY NIGHT. TEMPERATURES ARE GOING TO BE A LITTLE TRICKY...DEPENDING ON IF THERE IS A SNOW PACK OR NOT. NO PRECIPITATION IS ANTICIPATED THROUGH FRIDAY...EVEN DESPITE THE POTENT SHORTWAVE PASSAGE...MAINLY DUE TO A LACK OF MOISTURE. FOR THE WEEKEND...THE TROUGHING IN GENERAL SHIFTS EAST...WHICH WILL ALLOW 500MB HEIGHTS TO RISE AND TEMPERATURES TO MODERATE. WE ARE STILL PROGGED TO STAY IN NORTHWEST FLOW...HOWEVER. A SHORTWAVE IS EXPECTED TO DROP THROUGH THE NORTHWEST FLOW ON SATURDAY...AND HAVE KEPT SOME CONSENSUS 20-40 PERCENT CHANCES WITH IT. DRY WEATHER SHOULD FOLLOW IN ITS WAKE FOR SUNDAY AS SUBSIDENCE AND HIGH PRESSURE BUILD IN. && .AVIATION...THROUGH 18Z TUESDAY 1159 AM CST MON JAN 28 2013 DENSE FOG WILL PERSIST AT KRST THROUGH LATE AFTERNOON WITH VISIBILITIES AROUND 1/4 MILE OR LESS AT TIMES. THE DENSE FOG IS EXPECTED TO CONTINUE INTO THE OVERNIGHT HOURS. THERE COULD BE A BRIEF PERIOD OF IMPROVEMENT TO IFR CONDITIONS LATE THIS AFTERNOON BEFORE DENSE FOG REDEVELOPS THIS EVENING. PLAN ON IFR CONDITIONS AT KLSE THROUGH THE AFTERNOON HOURS IN LOW STRATUS WITH CEILINGS AROUND 800 FT. SHOWERS AND PERHAPS A FEW THUNDERSTORMS ARE POSSIBLE TONIGHT AS A WARM FRONT LIFTS INTO THE REGION. FOG AND LOW STATUS WILL CONTINUE THROUGH THE OVERNIGHT HOURS INTO EARLY TUESDAY MORNING. SOUTH/SOUTHEAST WINDS ARE EXPECTED TO INCREASE TONIGHT INTO THE 9 TO 13 KT RANGE. && .ARX WATCHES/WARNINGS/ADVISORIES... 1159 AM CST MON JAN 28 2013 WI...NONE. MN...DENSE FOG ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR MNZ079- 086>088-094>096. IA...DENSE FOG ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR IAZ008>011- 018-019-029-030. && $$ SHORT TERM...AJ LONG TERM....AJ AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
540 AM CST MON JAN 28 2013 .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT 344 AM CST MON JAN 28 2013 NUMEROUS FORECAST CONCERNS: 1. DENSE FOG THIS MORNING 2. TEMPERATURES THROUGH TUESDAY 3. POTENTIAL FOR FREEZING RAIN/DRIZZLE TONIGHT 4. POTENTIAL FOR MORE DENSE FOG TONIGHT. 5. THUNDERSTORM POTENTIAL TONIGHT/TUESDAY 6. POSSIBLY ANOTHER INTERESTING SYSTEM FOR TUESDAY NIGHT/WEDNESDAY CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING OVER THE WESTERN U.S....RIDGING OVER THE EASTERN TWO THIRDS OF THE U.S....WITH A SHORTWAVE TOPPING THIS RIDGING STRETCHED ACROSS WESTERN WI. THIS SHORTWAVE WAS THE ONE RESPONSIBLE FOR BRINGING MUCH OF THE WINTRY PRECIPITATION YESTERDAY TO THE FORECAST AREA. THIS PRECIPITATION HAS NOW SHIFTED NORTH INTO UPPER MICHIGAN. STILL DEALING WITH SOME DRIZZLE/FREEZING DRIZZLE...BUT MUCH OF THIS HAS MOVED OFF TO THE EAST INTO EASTERN WISCONSIN. PLENTY OF LOW CLOUDS REMAIN DUE TO TRAPPED LOW LEVEL MOISTURE BELOW A SUBSIDENCE INVERSION PRODUCED BY THE SHORTWAVE. 00Z DVN AND OAX SOUNDINGS ARE MOST REPRESENTATIVE OF THIS TRAPPED LOW LEVEL MOISTURE. THE RECENT PRECIPITATION INTO THE COOL AIRMASS THAT PRE-EXISTED THE PRECIPITATION...COMBINED WITH A WEAKENING PRESSURE GRADIENT ASSOCIATED WITH A SURFACE LOW NOW IN NORTHEAST IOWA...HAS RESULTED IN AN EXPANSION OF DENSE FOG FROM OMAHA NE NORTHEAST INTO THE SOUTHERN HALF OF THE FORECAST AREA. SOUTH OF THIS LOW PRESSURE AREA...TEMPERATURES CLIMB WELL INTO THE 30S AND EVEN UPPER 40S ACROSS SOUTHERN IOWA. FARTHER SOUTH...TEMPERATURES AND DEWPOINTS ARE IN THE 50S ACROSS MISSOURI. NORTH OF THE LOW...TEMPERATURES ARE HOLDING NEAR OR JUST BELOW FREEZING. OTHER NOTES...A LARGE AREA OF DRY AIR IS NOTED FROM NORTHERN MEXICO INTO THE FORECAST AREA ON WATER VAPOR. DESPITE THIS UPPER LEVEL DRY AIR...00Z PRECIPITABLE WATER PLOT FROM SOUNDINGS SHOWED 0.7-1.1 INCH READINGS FROM THE TEXAS GULF COAST NORTH TO THE FORECAST AREA...ANYWHERE FROM 200-330 PERCENT OF NORMAL. TO THE WEST...LOW PRESSURE HAS BEEN FORMING OVER NORTHEAST COLORADO DOWNSTREAM OF THE WESTERN TROUGH. PRETTY POTENT SHORTWAVE TOO AT THE BASE OF THE TROUGH IN SOUTHERN CALIFORNIA. TODAY...MUCH OF THE DAY WILL FEATURE SUBSIDENCE IN THE WAKE OF THE SHORTWAVE THAT BROUGHT THE WINTRY MIX YESTERDAY. HIGH PRESSURE SHOULD BUILD IN TOO IN THE WAKE OF THE SURFACE LOW CURRENTLY IN NORTHEAST IOWA. THUS...ANTICIPATING A DRY DAY. THERE ARE A COUPLE FORECAST ISSUES...THOUGH. FIRST IS THE CLOUDS. THERE ARE SOME HINTS IN THE 28.00Z NAM/GFS SOUNDINGS THAT THE CLOUDS MAY TRY TO BREAK UP SOMEWHAT DURING THE AFTERNOON. THE CAUSE IS A COMBINATION OF PERSISTENT DEEP LAYER SUBSIDENCE AND DIURNAL MIXING. ALTHOUGH LIGHT WINDS ARE A PROBLEM FOR MIXING OUT THE CLOUDS...FEEL THE AFOREMENTIONED TWO REASONS SOUND REASONABLE TO MENTION SOME CLEARING IN THE FORECAST. THIS PARTIAL CLEARING COMBINED WITH 925MB TEMPS PROGGED AT 18Z IN THE -2C NORTH TO +2C SOUTH SHOULD ALLOW TEMPERATURES TO CLIMB INTO THE MID 30S NORTH TO LOW 40S SOUTH. THE NEXT CONCERN IS THE MORNING FOG. HAVE ISSUED A DENSE FOG ADVISORY TO COVER THE LIGHT WINDS AND RECENT MOISTURE...VALID TIL NOON. IT MAY BE EXPANDED FURTHER NORTHEAST. ASSUMING THE BREAKS IN THE CLOUDS DEVELOP AS PLANNED...THE DENSE FOG ADVISORY END TIME OF NOON SHOULD WORK OUT. TONIGHT...MODELS ALL SHOW THAT THE POTENT SHORTWAVE IN SOUTHERN CALIFORNIA IS GOING TO EJECT NORTHEASTWARD DURING THIS PERIOD...IN RESPONSE TO YET ANOTHER SHORTWAVE IN NORTH CALIFORNIA THAT DROPS SOUTH THROUGH THE STATE. AS THE POTENT SHORTWAVE LIFTS NORTHEAST TO ABOUT EASTERN SOUTH DAKOTA BY 12Z TUESDAY...IT BRINGS AND DEEPENS THE SURFACE LOW WITH IT. MODELS HAVE TRENDED WEST WITH BOTH FEATURES...WITH THE LOW NOW REACHING NEAR MASON CITY BY 12Z TUESDAY. A MORE WESTWARD TRACK MEANS A COUPLE OF THINGS: 1. MORE WARM AIR WILL SPREAD ALOFT OVER THE FORECAST AREA. IN FACT...MAX TEMPERATURES ALOFT ARE NOW INDICATED BETWEEN 6-14C... WHICH IS PLENTY WARM ENOUGH TO KEEP THE PRECIP IN A LIQUID FORM IN THE AIR. IN ADDITION...THERE ARE NO INDICATIONS OF ICE IN THE CLOUDS THROUGHOUT THE NIGHT...ALSO SUPPORTING LIQUID. THUS...SURFACE TEMPERATURES WILL DETERMINE WHETHER ANY FREEZING OCCURS. THE PARTIAL CLEARING THAT DEVELOPS THIS AFTERNOON MAY ALLOW TEMPERATURES TO BRIEFLY DIP BELOW FREEZING THIS EVENING...BEFORE WARM ADVECTION KICKS IN AND BRINGS TEMPS UP. IN FACT...THE WARMING IS PRETTY IMPRESSIVE...WITH BOTH THE 28.00Z CANADIAN AND 27.12Z ECMWF BRINGING 50S INTO THE SOUTHEASTERN THIRD OF THE FORECAST AREA. 2. PRECIPITATION CHANCES. AS THE LOW LIFTS NORTHEAST...925-850MB MOISTURE TRANSPORT AND 285-295K LIFT INCREASE SOUTHWEST TO NORTHEAST ACROSS THE FORECAST AREA DURING THE EVENING. ALL MODELS HINT THAT THIS WILL RESULT IN NOT ONLY CLOUDS RE-FORMING...BUT ALSO THE DEVELOPMENT OF DRIZZLE. SINCE MUCH OF THE AREA COULD SEE A FEW HUNDREDTHS...DRAMATICALLY INCREASED PRECIPITATION CHANCES. ALSO INCREASED PRECIPITATION CHANCES FOR ITEM NUMBER 3 BELOW. 3. SHOWER/THUNDERSTORM POTENTIAL. THERE ARE INDICATIONS AFTER MIDNIGHT IN THE SOUTHEASTERN HALF OF THE AREA OF SOME SHOWERS DEVELOPING. THE 28.00Z NAM HAS UPWARDS OF 500 J/KG OF CAPE LIFTED FROM 900MB NEAR BOSCOBEL AT 09Z. THIS CAPE WAS NOTED YESTERDAY...BUT OFF TO THE EAST OF US GIVEN THE FARTHER EAST LOW TRACK AT THE TIME. NOW THAT THE LOW TRACK IS FARTHER WEST...THE INSTABILITY SHIFTS A BIT WEST. THE 28.00Z UKMET/ECMWF ALSO HINT AT THE INSTABILITY... MORESO THAN THE 28.00Z GFS. IN ANY EVENT...ADDED A CHANCE OF THUNDERSTORMS IN THE SOUTHEAST HALF OF THE AREA AFTER MIDNIGHT. PROMISING SCENARIO FOR THUNDERSTORMS TOO WITH THE CAPE GETTING INGESTED INTO THE LOW LEVEL FRONTOGENESIS CIRCULATION. CANNOT RULE OUT SOME SMALL HAIL TOO GIVEN THE FORCING...CAPE AND FREEZING LEVELS AROUND 8000 FT. ALSO TO NOTE IS THAT PRECIPITABLE WATER VALUES ARE AROUND 4 STANDARD DEVIATIONS ABOVE NORMAL AT 12Z TUESDAY...OR AROUND 1 INCH. 4. FOG...THE PARTIAL CLEARING IN THE EVENING COMBINED WITH MOISTURE COMING BACK IN IS FAVORABLE FOR FOG FORMATION. A DENSE FOG ADVISORY WILL LIKELY BE NEEDED AGAIN. THE FOG MAY TRY TO CLEAR OUT AS WARM AIR APPROACHES...BUT AT THE SAME TIME DEWPOINTS ARE RISING. TUESDAY...THE SHORTWAVE OVER EASTERN SOUTH DAKOTA AT 12Z IS PROGGED TO LIFT UP INTO NORTHWEST ONTARIO...BRINGING THE SURFACE LOW THROUGH EAU CLAIRE WI AND INTO EASTERN LAKE SUPERIOR AROUND 00Z WEDNESDAY. IT APPEARS THAT THE COLD FRONT ASSOCIATED WITH THIS LOW WILL END UP CROSSING THE FORECAST AREA WEST TO EAST THROUGH THE DAY. THIS MEANS HIGHS COULD VARY GREATLY ACROSS THE FORECAST AREA WEST TO EAST...AND THAT WE SHOULD SEE A FALLING TEMPERATURE CURVE...ESPECIALLY DURING THE AFTERNOON. DRAMATICALLY INCREASED HIGH TEMPERATURES WITH THE FARTHER WEST TRACK...TOWARDS THE 28.00Z ECMWF. THE 28.00Z REGIONAL CANADIAN IS REALLY IMPRESSIVE...A 63F HIGH FOR THE PLATTEVILLE AREA. DID NOT GO THAT HIGH...BUT SOMETHING TO WATCH. REGARDING PRECIPITATION...MAY STILL BE DEALING WITH SOME LIGHT DRIZZLE IN THE MORNING FOR MOST LOCATIONS...THEN DRY ADVECTION COMES IN BEHIND THE COLD FRONT TO END THE PRECIPITATION FOR THE AFTERNOON. WE WILL HAVE TO WATCH THE COLD FRONT AND FRONTOGENESIS ALONG IT. IN THE CASE OF THE 28.00Z NAM/ECMWF...THEY STILL HAVE SOME SHOWER/THUNDERSTORM POTENTIAL IN THE MORNING BEFORE THE FRONT PUSHES EAST. THUS...HAVE INCLUDED SHOWER AND THUNDERSTORMS IN THE MORNING. TUESDAY NIGHT INTO WEDNESDAY...THINGS MAY GET INTERESTING AGAIN. ALL MODELS INDICATE THAT THE SHORTWAVE DIGGING THROUGH CALIFORNIA THROUGH TONIGHT STRENGTHENS AS IT REACHES THE BASE OF THE TROUGH. IN THE CASE OF THE 28.00Z GFS/UKMET...THEY BRING THIS INTENSIFYING SHORTWAVE NORTHEAST THROUGH THE PLAINS...DEEPENING A SURFACE LOW ALONG THE TRAILING COLD FRONT FROM TUESDAYS SYSTEM. SHOULD THIS SCENARIO PLAY OUT...WE WOULD BE LOOKING AT A DEFORMATION BAND OF ACCUMULATING SNOW IMPACTING THE AREA AFTER MIDNIGHT TUESDAY MORNING THROUGH AT LEAST MID-DAY WEDNESDAY. BLOWING SNOW WOULD ACCOMPANY IT AS WELL GIVEN INTENSIFYING WINDS. ON THE OTHER HAND...THE 28.00Z ECMWF/CANADIAN/NAM KEEP THIS INTENSIFYING SHORTWAVE TRACKING MORE EAST-NORTHEAST...CALL IT MORE OF A POSITIVE TILT VERSUS A NEUTRAL TILT OF THE GFS/UKMET. THESE MODELS ALSO HAVE THE LOW DEVELOPING ON THE FRONT...BUT BECAUSE OF THE SHORTWAVE TRACK/TILT...THERE REALLY IS NO DEFORMATION BAND AND OUR AREA ENDS UP DRY. SINCE THERE ARE TWO PLAUSIBLE SITUATIONS...WILL TRY TO COMPROMISE AND HAVE 20 PERCENT CHANCES OF SNOW IN FOR BOTH TUESDAY NIGHT AND WEDNESDAY. THIS PERIOD REMAINS HIGHLY UNCERTAIN AND REALLY NEEDS TO BE WATCHED. BOTH SCENARIOS WOULD END UP HAVING COLD ADVECTION AND INCREASING WINDS. IN FACT...TEMPERATURES SHOULD JUST KEEP ON FALLING. WENT WITH A BLEND OF GUIDANCE FOR HIGHS AND LOWS. WEDNESDAY NIGHT...WHETHER A SYSTEM IMPACTS THE AREA ON WEDNESDAY OR NOT...MODELS ARE IN GOOD AGREEMENT ON A DRY FORECAST AS THE AREA LIES IN SUBSIDENCE BUT STILL GENERAL UPPER TROUGHING ALOFT. THERE WILL BE A POTENT SHORTWAVE APPROACHING THE AREA FROM THE NORTHWEST...DROPPING INTO MN BY 12Z. THIS SHORTWAVE IS CURRENTLY UP IN THE YUKON TERRITORY...THUS EXPECT A SURGE OF ARCTIC AIR WITH IT. BY 12Z THURSDAY...THE 850MB TEMPS ARE PROGGED TO FALL TO -16 TO -20C OVER THE AREA...WITH -24C READINGS LURKING UP AROUND FARGO. THIS CONTINUED COLD AIR ADVECTING IN WILL HELP SEND LOWS DOWN INTO THE 5 BELOW TO 5 ABOVE RANGE. .LONG TERM...THURSDAY THROUGH SUNDAY NIGHT 344 AM CST MON JAN 28 2013 28.00Z ECMWF/GFS/CANADIAN AND ECMWF ENSEMBLES ARE IN REALLY GOOD AGREEMENT WITH THE UPPER LEVEL AND EVEN SURFACE PATTERNS THROUGH THE LONG TERM PERIOD. DEEP TROUGHING IS PROGGED OVER THE EASTERN TWO THIRDS OF CANADA DOWN INTO OUR AREA AND THE GREAT LAKES REGION FOR THURSDAY INTO FRIDAY...AIDED BY THAT POTENT SHORTWAVE DROPPING INTO MN AT 12Z THURSDAY. THOSE COLD 850MB TEMPS NEAR FARGO ND SLIDE INTO THE AREA ON THURSDAY...SETTING THE STAGE FOR A CHILLY THURSDAY NIGHT. ARCTIC HIGH PRESSURE LOOKS TO DROP INTO WESTERN IOWA BY 12Z FRIDAY...SO THERE IS GOING TO BE A NORTHWESTERLY BREEZE THE ENTIRE TIME FROM THURSDAY INTO THURSDAY NIGHT. THUS...EXPECT WIND CHILLS TO BE AN ISSUE. ADVISORIES STILL LOOK LIKELY FOR THURSDAY MORNING AND THURSDAY NIGHT. TEMPERATURES ARE GOING TO BE A LITTLE TRICKY...DEPENDING ON IF THERE IS A SNOW PACK OR NOT. NO PRECIPITATION IS ANTICIPATED THROUGH FRIDAY...EVEN DESPITE THE POTENT SHORTWAVE PASSAGE...MAINLY DUE TO A LACK OF MOISTURE. FOR THE WEEKEND...THE TROUGHING IN GENERAL SHIFTS EAST...WHICH WILL ALLOW 500MB HEIGHTS TO RISE AND TEMPERATURES TO MODERATE. WE ARE STILL PROGGED TO STAY IN NORTHWEST FLOW...HOWEVER. A SHORTWAVE IS EXPECTED TO DROP THROUGH THE NORTHWEST FLOW ON SATURDAY...AND HAVE KEPT SOME CONSENSUS 20-40 PERCENT CHANCES WITH IT. DRY WEATHER SHOULD FOLLOW IN ITS WAKE FOR SUNDAY AS SUBSIDENCE AND HIGH PRESSURE BUILD IN. && .AVIATION...TODAY AND TONIGHT 540 AM CST MON JAN 28 2013 WIDESPREAD IFR/LIFR CIGS/VSBYS IN BR/FG WILL REMAIN OVER THE AREA THIS MORNING AS ABUNDANT LOW LEVEL MOISTURE REMAINS TRAPPED OVER THE AREA BETWEEN A SFC-900MB INVERSION AND THE COLD...ICE/SLEET COVERED GROUND. SOME INDICATIONS SUBSIDENCE IN THE WAKE OF THE DEPARTING LOW AND WITH WEAK RIDGING BUILD IN WILL ERODE THE LOW LEVEL MOISTURE/ CLOUD DECK THIS AFTERNOON BUT INVERSION REMAINS STRONG WITH MINIMAL CHANGE OF THE SFC-900MB AIRMASS. LEFT BKN IFR CIGS ACROSS THE AREA THRU THE AFTERNOON BUT APPEARS FOG SHOULD LIFT WITH MVFR VSBYS FOR THE AFTERNOON INTO THE EARLY EVENING. ANOTHER CENTRAL PLAINS LOW HEADS TOWARD THE AREA TONIGHT...WITH ANOTHER SURGE OF GULF OF MX MOISTURE. CIGS/VSBYS TO LOWER BACK INTO IFR/LIFR TONIGHT AS THIS MOISTURE SPREADS NORTH OVER THE COLD GROUND. MORE -DZ/-SHRA TO SPREAD ACROSS THE AREA TONIGHT AS THE DEEPER MOISTURE/LIFT ARRIVES. SOME WEAK INSTABILITY SPREADS INTO THE AREA AS WELL TONIGHT. THIS COMBINED WITH LIFT/DIVERGENCE ALOFT MAY RESULT IN A FEW TSRA FOR KLSE AND LOCATIONS EAST/SOUTH OF KLSE. THIS VERY LATE IN THE TAF PERIOD AND GIVEN UNCERTAINTIES DID NOT INCLUDE ANY TSRA/CB MENTION AT THIS TIME. BOUNDARY LAYER AIR TEMPS LOOKING TO BE ABOVE 32F TONIGHT...BUT SOME FREEZING/ICING MAY STILL OCCUR ON RUNWAYS DUE TO THE COLD/FROZEN GROUND. && .ARX WATCHES/WARNINGS/ADVISORIES... 344 AM CST MON JAN 28 2013 WI...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR WIZ041-053>055-061. MN...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR MNZ079-086>088- 094>096. IA...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR IAZ008>011-018-019- 029-030. && $$ SHORT TERM...AJ LONG TERM....AJ AVIATION.....RRS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
345 AM CST MON JAN 28 2013 .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT 344 AM CST MON JAN 28 2013 NUMEROUS FORECAST CONCERNS: 1. DENSE FOG THIS MORNING 2. TEMPERATURES THROUGH TUESDAY 3. POTENTIAL FOR FREEZING RAIN/DRIZZLE TONIGHT 4. POTENTIAL FOR MORE DENSE FOG TONIGHT. 5. THUNDERSTORM POTENTIAL TONIGHT/TUESDAY 6. POSSIBLY ANOTHER INTERESTING SYSTEM FOR TUESDAY NIGHT/WEDNESDAY CURRENTLY AS OF 09Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING OVER THE WESTERN U.S....RIDGING OVER THE EASTERN TWO THIRDS OF THE U.S....WITH A SHORTWAVE TOPPING THIS RIDGING STRETCHED ACROSS WESTERN WI. THIS SHORTWAVE WAS THE ONE RESPONSIBLE FOR BRINGING MUCH OF THE WINTRY PRECIPITATION YESTERDAY TO THE FORECAST AREA. THIS PRECIPITATION HAS NOW SHIFTED NORTH INTO UPPER MICHIGAN. STILL DEALING WITH SOME DRIZZLE/FREEZING DRIZZLE...BUT MUCH OF THIS HAS MOVED OFF TO THE EAST INTO EASTERN WISCONSIN. PLENTY OF LOW CLOUDS REMAIN DUE TO TRAPPED LOW LEVEL MOISTURE BELOW A SUBSIDENCE INVERSION PRODUCED BY THE SHORTWAVE. 00Z DVN AND OAX SOUNDINGS ARE MOST REPRESENTATIVE OF THIS TRAPPED LOW LEVEL MOISTURE. THE RECENT PRECIPITATION INTO THE COOL AIRMASS THAT PRE-EXISTED THE PRECIPITATION...COMBINED WITH A WEAKENING PRESSURE GRADIENT ASSOCIATED WITH A SURFACE LOW NOW IN NORTHEAST IOWA...HAS RESULTED IN AN EXPANSION OF DENSE FOG FROM OMAHA NE NORTHEAST INTO THE SOUTHERN HALF OF THE FORECAST AREA. SOUTH OF THIS LOW PRESSURE AREA...TEMPERATURES CLIMB WELL INTO THE 30S AND EVEN UPPER 40S ACROSS SOUTHERN IOWA. FARTHER SOUTH...TEMPERATURES AND DEWPOINTS ARE IN THE 50S ACROSS MISSOURI. NORTH OF THE LOW...TEMPERATURES ARE HOLDING NEAR OR JUST BELOW FREEZING. OTHER NOTES...A LARGE AREA OF DRY AIR IS NOTED FROM NORTHERN MEXICO INTO THE FORECAST AREA ON WATER VAPOR. DESPITE THIS UPPER LEVEL DRY AIR...00Z PRECIPITABLE WATER PLOT FROM SOUNDINGS SHOWED 0.7-1.1 INCH READINGS FROM THE TEXAS GULF COAST NORTH TO THE FORECAST AREA...ANYWHERE FROM 200-330 PERCENT OF NORMAL. TO THE WEST...LOW PRESSURE HAS BEEN FORMING OVER NORTHEAST COLORADO DOWNSTREAM OF THE WESTERN TROUGH. PRETTY POTENT SHORTWAVE TOO AT THE BASE OF THE TROUGH IN SOUTHERN CALIFORNIA. TODAY...MUCH OF THE DAY WILL FEATURE SUBSIDENCE IN THE WAKE OF THE SHORTWAVE THAT BROUGHT THE WINTRY MIX YESTERDAY. HIGH PRESSURE SHOULD BUILD IN TOO IN THE WAKE OF THE SURFACE LOW CURRENTLY IN NORTHEAST IOWA. THUS...ANTICIPATING A DRY DAY. THERE ARE A COUPLE FORECAST ISSUES...THOUGH. FIRST IS THE CLOUDS. THERE ARE SOME HINTS IN THE 28.00Z NAM/GFS SOUNDINGS THAT THE CLOUDS MAY TRY TO BREAK UP SOMEWHAT DURING THE AFTERNOON. THE CAUSE IS A COMBINATION OF PERSISTENT DEEP LAYER SUBSIDENCE AND DIURNAL MIXING. ALTHOUGH LIGHT WINDS ARE A PROBLEM FOR MIXING OUT THE CLOUDS...FEEL THE AFOREMENTIONED TWO REASONS SOUND REASONABLE TO MENTION SOME CLEARING IN THE FORECAST. THIS PARTIAL CLEARING COMBINED WITH 925MB TEMPS PROGGED AT 18Z IN THE -2C NORTH TO +2C SOUTH SHOULD ALLOW TEMPERATURES TO CLIMB INTO THE MID 30S NORTH TO LOW 40S SOUTH. THE NEXT CONCERN IS THE MORNING FOG. HAVE ISSUED A DENSE FOG ADVISORY TO COVER THE LIGHT WINDS AND RECENT MOISTURE...VALID TIL NOON. IT MAY BE EXPANDED FURTHER NORTHEAST. ASSUMING THE BREAKS IN THE CLOUDS DEVELOP AS PLANNED...THE DENSE FOG ADVISORY END TIME OF NOON SHOULD WORK OUT. TONIGHT...MODELS ALL SHOW THAT THE POTENT SHORTWAVE IN SOUTHERN CALIFORNIA IS GOING TO EJECT NORTHEASTWARD DURING THIS PERIOD...IN RESPONSE TO YET ANOTHER SHORTWAVE IN NORTH CALIFORNIA THAT DROPS SOUTH THROUGH THE STATE. AS THE POTENT SHORTWAVE LIFTS NORTHEAST TO ABOUT EASTERN SOUTH DAKOTA BY 12Z TUESDAY...IT BRINGS AND DEEPENS THE SURFACE LOW WITH IT. MODELS HAVE TRENDED WEST WITH BOTH FEATURES...WITH THE LOW NOW REACHING NEAR MASON CITY BY 12Z TUESDAY. A MORE WESTWARD TRACK MEANS A COUPLE OF THINGS: 1. MORE WARM AIR WILL SPREAD ALOFT OVER THE FORECAST AREA. IN FACT...MAX TEMPERATURES ALOFT ARE NOW INDICATED BETWEEN 6-14C... WHICH IS PLENTY WARM ENOUGH TO KEEP THE PRECIP IN A LIQUID FORM IN THE AIR. IN ADDITION...THERE ARE NO INDICATIONS OF ICE IN THE CLOUDS THROUGHOUT THE NIGHT...ALSO SUPPORTING LIQUID. THUS...SURFACE TEMPERATURES WILL DETERMINE WHETHER ANY FREEZING OCCURS. THE PARTIAL CLEARING THAT DEVELOPS THIS AFTERNOON MAY ALLOW TEMPERATURES TO BRIEFLY DIP BELOW FREEZING THIS EVENING...BEFORE WARM ADVECTION KICKS IN AND BRINGS TEMPS UP. IN FACT...THE WARMING IS PRETTY IMPRESSIVE...WITH BOTH THE 28.00Z CANADIAN AND 27.12Z ECMWF BRINGING 50S INTO THE SOUTHEASTERN THIRD OF THE FORECAST AREA. 2. PRECIPITATION CHANCES. AS THE LOW LIFTS NORTHEAST...925-850MB MOISTURE TRANSPORT AND 285-295K LIFT INCREASE SOUTHWEST TO NORTHEAST ACROSS THE FORECAST AREA DURING THE EVENING. ALL MODELS HINT THAT THIS WILL RESULT IN NOT ONLY CLOUDS RE-FORMING...BUT ALSO THE DEVELOPMENT OF DRIZZLE. SINCE MUCH OF THE AREA COULD SEE A FEW HUNDREDTHS...DRAMATICALLY INCREASED PRECIPITATION CHANCES. ALSO INCREASED PRECIPITATION CHANCES FOR ITEM NUMBER 3 BELOW. 3. SHOWER/THUNDERSTORM POTENTIAL. THERE ARE INDICATIONS AFTER MIDNIGHT IN THE SOUTHEASTERN HALF OF THE AREA OF SOME SHOWERS DEVELOPING. THE 28.00Z NAM HAS UPWARDS OF 500 J/KG OF CAPE LIFTED FROM 900MB NEAR BOSCOBEL AT 09Z. THIS CAPE WAS NOTED YESTERDAY...BUT OFF TO THE EAST OF US GIVEN THE FARTHER EAST LOW TRACK AT THE TIME. NOW THAT THE LOW TRACK IS FARTHER WEST...THE INSTABILITY SHIFTS A BIT WEST. THE 28.00Z UKMET/ECMWF ALSO HINT AT THE INSTABILITY... MORESO THAN THE 28.00Z GFS. IN ANY EVENT...ADDED A CHANCE OF THUNDERSTORMS IN THE SOUTHEAST HALF OF THE AREA AFTER MIDNIGHT. PROMISING SCENARIO FOR THUNDERSTORMS TOO WITH THE CAPE GETTING INGESTED INTO THE LOW LEVEL FRONTOGENESIS CIRCULATION. CANNOT RULE OUT SOME SMALL HAIL TOO GIVEN THE FORCING...CAPE AND FREEZING LEVELS AROUND 8000 FT. ALSO TO NOTE IS THAT PRECIPITABLE WATER VALUES ARE AROUND 4 STANDARD DEVIATIONS ABOVE NORMAL AT 12Z TUESDAY...OR AROUND 1 INCH. 4. FOG...THE PARTIAL CLEARING IN THE EVENING COMBINED WITH MOISTURE COMING BACK IN IS FAVORABLE FOR FOG FORMATION. A DENSE FOG ADVISORY WILL LIKELY BE NEEDED AGAIN. THE FOG MAY TRY TO CLEAR OUT AS WARM AIR APPROACHES...BUT AT THE SAME TIME DEWPOINTS ARE RISING. TUESDAY...THE SHORTWAVE OVER EASTERN SOUTH DAKOTA AT 12Z IS PROGGED TO LIFT UP INTO NORTHWEST ONTARIO...BRINGING THE SURFACE LOW THROUGH EAU CLAIRE WI AND INTO EASTERN LAKE SUPERIOR AROUND 00Z WEDNESDAY. IT APPEARS THAT THE COLD FRONT ASSOCIATED WITH THIS LOW WILL END UP CROSSING THE FORECAST AREA WEST TO EAST THROUGH THE DAY. THIS MEANS HIGHS COULD VARY GREATLY ACROSS THE FORECAST AREA WEST TO EAST...AND THAT WE SHOULD SEE A FALLING TEMPERATURE CURVE...ESPECIALLY DURING THE AFTERNOON. DRAMATICALLY INCREASED HIGH TEMPERATURES WITH THE FARTHER WEST TRACK...TOWARDS THE 28.00Z ECMWF. THE 28.00Z REGIONAL CANADIAN IS REALLY IMPRESSIVE...A 63F HIGH FOR THE PLATTEVILLE AREA. DID NOT GO THAT HIGH...BUT SOMETHING TO WATCH. REGARDING PRECIPITATION...MAY STILL BE DEALING WITH SOME LIGHT DRIZZLE IN THE MORNING FOR MOST LOCATIONS...THEN DRY ADVECTION COMES IN BEHIND THE COLD FRONT TO END THE PRECIPITATION FOR THE AFTERNOON. WE WILL HAVE TO WATCH THE COLD FRONT AND FRONTOGENESIS ALONG IT. IN THE CASE OF THE 28.00Z NAM/ECMWF...THEY STILL HAVE SOME SHOWER/THUNDERSTORM POTENTIAL IN THE MORNING BEFORE THE FRONT PUSHES EAST. THUS...HAVE INCLUDED SHOWER AND THUNDERSTORMS IN THE MORNING. TUESDAY NIGHT INTO WEDNESDAY...THINGS MAY GET INTERESTING AGAIN. ALL MODELS INDICATE THAT THE SHORTWAVE DIGGING THROUGH CALIFORNIA THROUGH TONIGHT STRENGTHENS AS IT REACHES THE BASE OF THE TROUGH. IN THE CASE OF THE 28.00Z GFS/UKMET...THEY BRING THIS INTENSIFYING SHORTWAVE NORTHEAST THROUGH THE PLAINS...DEEPENING A SURFACE LOW ALONG THE TRAILING COLD FRONT FROM TUESDAYS SYSTEM. SHOULD THIS SCENARIO PLAY OUT...WE WOULD BE LOOKING AT A DEFORMATION BAND OF ACCUMULATING SNOW IMPACTING THE AREA AFTER MIDNIGHT TUESDAY MORNING THROUGH AT LEAST MID-DAY WEDNESDAY. BLOWING SNOW WOULD ACCOMPANY IT AS WELL GIVEN INTENSIFYING WINDS. ON THE OTHER HAND...THE 28.00Z ECMWF/CANADIAN/NAM KEEP THIS INTENSIFYING SHORTWAVE TRACKING MORE EAST-NORTHEAST...CALL IT MORE OF A POSITIVE TILT VERSUS A NEUTRAL TILT OF THE GFS/UKMET. THESE MODELS ALSO HAVE THE LOW DEVELOPING ON THE FRONT...BUT BECAUSE OF THE SHORTWAVE TRACK/TILT...THERE REALLY IS NO DEFORMATION BAND AND OUR AREA ENDS UP DRY. SINCE THERE ARE TWO PLAUSIBLE SITUATIONS...WILL TRY TO COMPROMISE AND HAVE 20 PERCENT CHANCES OF SNOW IN FOR BOTH TUESDAY NIGHT AND WEDNESDAY. THIS PERIOD REMAINS HIGHLY UNCERTAIN AND REALLY NEEDS TO BE WATCHED. BOTH SCENARIOS WOULD END UP HAVING COLD ADVECTION AND INCREASING WINDS. IN FACT...TEMPERATURES SHOULD JUST KEEP ON FALLING. WENT WITH A BLEND OF GUIDANCE FOR HIGHS AND LOWS. WEDNESDAY NIGHT...WHETHER A SYSTEM IMPACTS THE AREA ON WEDNESDAY OR NOT...MODELS ARE IN GOOD AGREEMENT ON A DRY FORECAST AS THE AREA LIES IN SUBSIDENCE BUT STILL GENERAL UPPER TROUGHING ALOFT. THERE WILL BE A POTENT SHORTWAVE APPROACHING THE AREA FROM THE NORTHWEST...DROPPING INTO MN BY 12Z. THIS SHORTWAVE IS CURRENTLY UP IN THE YUKON TERRITORY...THUS EXPECT A SURGE OF ARCTIC AIR WITH IT. BY 12Z THURSDAY...THE 850MB TEMPS ARE PROGGED TO FALL TO -16 TO -20C OVER THE AREA...WITH -24C READINGS LURKING UP AROUND FARGO. THIS CONTINUED COLD AIR ADVECTING IN WILL HELP SEND LOWS DOWN INTO THE 5 BELOW TO 5 ABOVE RANGE. .LONG TERM...THURSDAY THROUGH SUNDAY NIGHT 344 AM CST MON JAN 28 2013 28.00Z ECMWF/GFS/CANADIAN AND ECMWF ENSEMBLES ARE IN REALLY GOOD AGREEMENT WITH THE UPPER LEVEL AND EVEN SURFACE PATTERNS THROUGH THE LONG TERM PERIOD. DEEP TROUGHING IS PROGGED OVER THE EASTERN TWO THIRDS OF CANADA DOWN INTO OUR AREA AND THE GREAT LAKES REGION FOR THURSDAY INTO FRIDAY...AIDED BY THAT POTENT SHORTWAVE DROPPING INTO MN AT 12Z THURSDAY. THOSE COLD 850MB TEMPS NEAR FARGO ND SLIDE INTO THE AREA ON THURSDAY...SETTING THE STAGE FOR A CHILLY THURSDAY NIGHT. ARCTIC HIGH PRESSURE LOOKS TO DROP INTO WESTERN IOWA BY 12Z FRIDAY...SO THERE IS GOING TO BE A NORTHWESTERLY BREEZE THE ENTIRE TIME FROM THURSDAY INTO THURSDAY NIGHT. THUS...EXPECT WIND CHILLS TO BE AN ISSUE. ADVISORIES STILL LOOK LIKELY FOR THURSDAY MORNING AND THURSDAY NIGHT. TEMPERATURES ARE GOING TO BE A LITTLE TRICKY...DEPENDING ON IF THERE IS A SNOW PACK OR NOT. NO PRECIPITATION IS ANTICIPATED THROUGH FRIDAY...EVEN DESPITE THE POTENT SHORTWAVE PASSAGE...MAINLY DUE TO A LACK OF MOISTURE. FOR THE WEEKEND...THE TROUGHING IN GENERAL SHIFTS EAST...WHICH WILL ALLOW 500MB HEIGHTS TO RISE AND TEMPERATURES TO MODERATE. WE ARE STILL PROGGED TO STAY IN NORTHWEST FLOW...HOWEVER. A SHORTWAVE IS EXPECTED TO DROP THROUGH THE NORTHWEST FLOW ON SATURDAY...AND HAVE KEPT SOME CONSENSUS 20-40 PERCENT CHANCES WITH IT. DRY WEATHER SHOULD FOLLOW IN ITS WAKE FOR SUNDAY AS SUBSIDENCE AND HIGH PRESSURE BUILD IN. && .AVIATION... 1045 PM CST SUN JAN 27 2013 SOME PATCHY/AREAS OF FZDZ WILL CONTINUE THROUGH ABOUT 09Z...MOSTLY AT KLSE...AS ISENTROPIC UPGLIDE CONTINUES TO WORK ON THE LOW SATURATION. FOG COULD BECOME A GREATER CONCERN OVERNIGHT AS BUFKIT SOUNDINGS HOLD ONTO THE ABUNDANT LOW LEVEL MOISTURE WHILE THE PRESSURE GRADIENT SLACKENS. SFC OBS OVER MUCH OF WESTERN IA POINT TO 1/2SM OR LOWER VSBYS FROM FG. THIS FOG LOOKS MORE LIKELY FOR KRST...AND WOULDN/T BE SURPRISED IF IT BOTTOMED OUT AT 1/4SM. WILL STICK WITH 1/2SM FOR NOW. DENSE FOG DOESN/T LOOK AS LIKELY AT KLSE...BUT TRENDS WILL HAVE TO BE MONITORED CLOSELY...AND UPDATES MADE AS NEEDED. MODELS ARE SUGGESTIVE THAT WE COULD BREAK OUT OF THE LOW CIGS INTO SCT CONDITIONS FOR A VERY SHORT PERIOD LATE TOMORROW AFTERNOON/EVENING /2-4 HOURS/. LOW STRATUS SHOULD QUICKLY RETURN THOUGH...AHEAD OF ANOTHER SYSTEM MOVING OUT OF THE PLAINS. PCPN WILL ACCOMPANY THESE CLOUDS...AND TRENDS POINT TO DZ/FZDZ. TEMPS WILL LIKELY WARM THROUGH THE NIGHT...SO IT COULD START AS FZDZ AND SWITCH TO DZ OVERNIGHT. && .ARX WATCHES/WARNINGS/ADVISORIES... 344 AM CST MON JAN 28 2013 WI...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR WIZ041-053>055-061. MN...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR MNZ079-086>088- 094>096. IA...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR IAZ008>011-018-019- 029-030. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
143 PM MST MON JAN 28 2013 .SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT... MAIN PROBLEM THIS PERIOD WILL BE SNOW OVER THE MTNS WITH SOME POTENTIAL WIND PROBLEMS WEDS. UPPER JET STREAK IS CURRENTLY SITUATED ACROSS NW COLORADO AND EASTERN WYOMING THIS AFTERNOON WITH A BAND OF ENHANCED SNOWS PROGRESSING EAST ACROSS EASTERN WYOMING. LIGHT SNOWS ALSO DEVELOPING OVER THE PANHANDLE AS UPPER DYNAMICS IMPROVING THERE. EXPECT THIS AREA OF SNOW TO CONTINUE TO WORK EAST ACROSS THESE AREAS INTO THIS EVENING AS THE JET ENERGY LIKEWISE MOVES EAST THEN DIMINISH LATER TONIGHT AS UPPER DYNAMICS MOVE OUT OF THE AREA. MAIN UPPER TROF AXIS WILL SHIFT EAST ACROSS THE REGION TUESDAY MORNING WHICH SHOULD BRING A SHORT LULL IN THE SNOW BEFORE ENHANCING AGAIN OVER THE HIGHER MTNS AS MOIST NW FLOW SETS UP. CURRENT HILITES LOOK PRETTY GOOD AND WILL MAINTAIN THEM AS IS. TEMPERATURES WILL BE ON THE COOL SIDE THROUGH WEDS. OTHER FACTOR WILL BE WINDS ON WEDS AS LEE TROF DEEPENS OVER THE HIGH PLAINS AND INCREASES THE PRESSURE GRADIENT ACROSS MAINLY SE WY. IN-HOUSE WIND PROGRAM INDICATES HEALTHY SFC GRADIENT THUS SHOULD BE PRETTY WINDY IN THE WIND PRONE AREAS. WILL HOLD OFF ON ANY HILITES FOR NOW BUT MAY EVENTUALLY BE NEEDED. .LONG TERM...THURSDAY THROUGH MONDAY GOING TO STILL BE DEALING WITH A NORTHWEST TO SOUTHEAST ORIENTED FRONT LAYING ALONG THE LARAMIE RANGE STARTING OFF THURSDAY MORNING. PRETTY GOOD THERMAL GRADIENT FROM WEST TO EAST WITH COLDEST AIR IN THE PANHANDLE. WEST TO NORTHWEST WINDS AT 700MB SHOULD KEEP UPSLOPING GOING IN THE SNOWY AND SIERRA MADRE RANGES. RAISE POPS TO LIKELY THERE FOR THURSDAY MORNING PERSISTING THROUGH THE AFTERNOON. GFS AND ECMWF MOVE BOUNDARY EAST INTO THE CENTRAL DAKOTAS AND NEBRASKA BY THURSDAY EVENING AS SURFACE HIGH NORTHEAST OF THE BOUNDARY SLIDES SOUTHEAST INTO IOWA. PRECIP SHOULD COME TO AN END THURSDAY EVENING WITH MAYBE SOME OROGRAPHIC SNOW IN THE SNOWY AND SIERRA MADRE RANGES. FRIDAY COULD BE WINDY AS GFS SHOWING 700MB WINDS INCREASING TO 50KTS. THE 700MB CRAIG TO CASPER HEIGHT GRADIENT RIGHT AROUND 50MTRS. 700MB TEMPERATURES WARM...INCREASING TO AROUND -6C FRIDAY AFTERNOON. STILL COLD IN THE PANHANDLE WITH 700MB TEMPERATURES AROUND -8C AND 850MB TEMPERATURES AROUND +2C. WENT A FEW DEGREES UNDER GUIDANCE FOR THE NORTHERN PANHANDLE ON FRIDAY HIGHS...WE WILL HAVE TO WAIT AND SEE WHAT IMPACT DOWNSLOPING PLAYS ON TEMPERATURES AS THIS TAKES PLACE. MAY HAVE GONE TOO COLD. UPPER RIDGE BUILDS IN FOR NEXT WEEKEND WITH 700MB TEMPERATURES CLIMBING TO -2C AS THE RIDGE BUILDS INTO THE AREA. HIGHS LOOK TO RETURN TO THE 40S WEST OF THE LARAMIE RANGE/MID 50S EAST SATURDAY AND POSSIBLY LOW 60S IN THE PANHANDLE FOR SUNDAY. && .AVIATION...18Z TAFS WIDESPREAD IFR EVENT UNFOLDING AS A COLD FRONT CONTINUES TO DROP SOUTH. NORTHEAST WINDS IN THE PANHANDLE HAVE PRODUCED WIDESPREAD IFR/VLIFR AT ALL AIRPORTS AND SNOW CONTINUES OUT BY RAWLINS. WITH THIS SLOW MOVING FRONT...CONDITIONS WILL NOT IMPROVE ANY DURING THE AFTERNOON HOURS AND WILL PERSIST THROUGH THE EVENING BEFORE NORTHWEST WINDS RETURN. CONFIDENCE HIGH ON THIS HAPPENING AS LATEST HRRR FORECAST SHOWING SOLID IFR AND BELOW CONDITIONS TO PERSIST ACROSS THE PANHANDLE AND EVENTUALLY INTO CHEYENNE BY LATE THIS AFTERNOON. && .FIRE WEATHER... NO CONCERNS EXPECTED WITH COOL TEMPERATURES AND HUMIDITIES WELL ABOVE CRITICAL LEVELS. GUSTY WINDS EXPECTED AROUND THE MOUNTAINS TUESDAY AND WEDNESDAY WITH QUITE GUSTY WINDS POSSIBLE IN WIND PRONE AREAS WEDNESDAY. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...WINTER STORM WARNING UNTIL 6 PM THURSDAY FOR WYZ112-WYZ114. WINTER WEATHER ADVISORY UNTIL 6 PM THURSDAY FOR WYZ113. WINTER WEATHER ADVISORY UNTIL 6 AM TUESDAY FOR WYZ103. NE...NONE. && $$ SHORT TERM/FIRE WEATHER...RE LONG TERM/AVIATION...CLAYCOMB
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1041 AM MST MON JAN 28 2013 .UPDATE... MOST SIGNIFICANT CHANGE WAS TO ALTER THE TIMING AND LENGTH OF THE WINTER WEATHER ADVISORY FOR THE NORTH LARAMIE RANGE. LATEST MODELS SHOW MOST OF THE SNOW FALLING THERE THIS AFTERNOON AND TONIGHT BEFORE WANING SIGNIFICANTLY LATE TONIGHT. ELSEWHERE HAVE MADE MINOR ADJUSTMENTS TO TEMPS AND POPS GIVEN CURRENT TRENDS. RE && .AVIATION...18Z TAFS WIDESPREAD IFR EVENT UNFOLDING AS A COLD FRONT CONTINUES TO DROP SOUTH. NORTHEAST WINDS IN THE PANHANDLE HAVE PRODUCED WIDESPREAD IFR/VLIFR AT ALL AIRPORTS AND SNOW CONTINUES OUT BY RAWLINS. WITH THIS SLOW MOVING FRONT...CONDITIONS WILL NOT IMPROVE ANY DURING THE AFTERNOON HOURS AND WILL PERSIST THROUGH THE EVENING BEFORE NORTHWEST WINDS RETURN. CONFIDENCE HIGH ON THIS HAPPENING AS LATEST HRRR FORECAST SHOWING SOLID IFR AND BELOW CONDITIONS TO PERSIST ACROSS THE PANHANDLE AND EVENTUALLY INTO CHEYENNE BY LATE THIS AFTERNOON. CLAYCOMB && .PREV DISCUSSION... /ISSUED 414 AM MST MON JAN 28 2013/ SHORT TERM...TODAY THROUGH WEDNESDAY... TODAY...CHALLENGES TODAY WILL BE TEMPERATURES AND AREAL COVERAGE OF PRECIPITATION ALONG WITH PRECIPITATION TYPE. CURRENTLY MSAS SHOWS SURFACE LOW PRESSURE DEVELOPING OVER NORTHERN COLORADO WITH A PSEUDO WARM FRONT EXTENDING FROM THE LOW ACROSS NORTHEAST COLORADO NEAR THE WYOMING STATE LINE. AREAS OF FOG HAVE DEVELOPED NORTH OF A DOUGLAS TO SCOTTSBLUFF LINE. 110 KNOT 300 MB JET ORIENTED SOUTHWEST TO NORTHEAST WILL MOVE WEST TO EAST ACROSS OUR COUNTIES ALONG WITH AN ASSOCIATED MID LEVEL SHORTWAVE TROUGH ALOFT AND COLD FRONT. WIDESPREAD SNOW WILL OCCUR THIS MORNING OVER CARBON COUNTY AND THE NEARBY MOUNTAINS DUE TO JET DYNAMICS AND THE BAROCLINIC BAND PASSAGE. ALSO EXPECTING AREAS OF FOG THIS MORNING NORTH OF A LARAMIE TO SCOTTSBLUFF LINE AS TEMPERATURES AND DEW POINTS NARROW...THOUGH FOG WILL BE MORE LIMITED ACROSS CARBON COUNTY WHERE SNOW OCCURS. FOR THIS AFTERNOON...THE SURFACE LOW WILL STRENGTHEN AS IT MOVES INTO NORTHWEST KANSAS. THE ASSOCIATED MID LEVEL SHORTWAVE TROUGH WILL MOVE ACROSS SOUTHEAST WYOMING WITH THE THE SURFACE COLD FRONT AND BAROCLINIC BAND SLIDING WEST TO EAST ACROSS OUR COUNTIES. BOTH THE NAM AND GFS SHOW THE LOW AND MID LEVELS BECOMING MORE SATURATED...THUS EXPECTING AT LEAST A SCATTERED COVERAGE OF SNOW ACROSS ALL BUT OUR NORTHERN CONVERSE AND NIOBRARA COUNTIES. PLUS LIFT WILL BE PRODUCED BY MID LEVEL CONVERGENCE ZONE OF WARM AIR ADVECTION...ALONG WITH LOW LEVEL UPSLOPE AND JET INDUCED DYNAMICS. WIDESPREAD SNOW TO DEVELOP AND SPREAD ACROSS THE SNOWY AND SIERRA MADRE RANGES. BASED ON EXPECTED CLOUD COVER AND EARLIER PASSAGE OF THE COLD FRONT...WILL GO CLOSER TO COLDER GUIDANCE NAM MAXIMA. TONIGHT...500 MB TROUGH AXIS MOVES EASTWARD ALONG THE WYOMING AND NEBRASKA STATE LINES WITH LOW AND MID LEVEL WINDS BECOMING WEST AND NORTHWEST...PRODUCING TEMPORARY LULL IN THE AREAL SNOW COVERAGE...WITH 30 TO 60 PERCENT POPS ACROSS THE SIERRA MADRE AND SNOWY RANGES AND NEARBY VALLEYS DUE TO OROGRAPHICS. TUESDAY...FLOW ALOFT TURNS NORTHWEST WITH COLDER AIR PLUNGING SOUTHWARD AT LOW AND MID LEVELS. MOIST FLOW ALOFT WILL COMBINE WITH OROGRAPHICS...140 KNOT JET DYNAMICS AND SHORTWAVE TROUGHS IN THE FLOW ALOFT TO PRODUCE WIDESPREAD SNOW ACROSS THE NORTHERN LARAMIE...SNOWY AND SIERRA MADRE RANGES AND THE UPPER NORTH PLATTE RIVER BASIN. UPON COORDINATION WITH OUR NEIGHBORS...AND AGREEMENT WITH THE HPC SNOWFALL EXPECTATIONS...WE HAVE UPGRADED TO A WINTER STORM WARNING FOR THE SNOWY AND SIERRA MADRE RANGES...WITH A WINTER WEATHER ADVISORY FOR THE UPPER NORTH PLATTE RIVER BASIN AND SARATOGA AND THE NORTHERN LARAMIE RANGE. WITH COLDER TEMPERATURES...EXPECTING SNOWFALL TO LIQUID RATIOS OF 20 OR 30 TO 1...THUS MORE SNOW WILL FALL ACROSS OUR WESTERN MOUNTAINS. SNOW SHADOWING EFFECT WILL OCCUR EAST OF A LUSK TO LARAMIE LINE WITH WEST AND NORTHWEST WINDS. BLUSTERY DAY WITH BRISK WEST WINDS AND AREAS OF BLOWING SNOW ACROSS OUR WESTERN MOUNTAINS. TUESDAY NIGHT...DEEP NORTHWEST UNIDIRECTIONAL FLOW FROM THE SURFACE TO MID LEVELS ALONG WITH PLENTY OF LOW AND MID LEVEL MOISTURE WILL KEEP THE SNOW MACHINE AND OROGRAPHICS GOING ACROSS THE NORTHERN LARAMIE...SNOWY AND SIERRA MADRE RANGES AND OVER THE SARATOGA VALLEY AREA WITH DOWNSLOPING PRODUCING SNOW SHADOW EFFECTS ELSEWHERE...AND A BRISK AND COLD NIGHT. WEDNESDAY...FLOW ALOFT BACKS SLIGHTLY AND BECOMES MORE CYCLONIC. PERSISTENT MOIST NORTHWEST FLOW ALONG WITH COLD TEMPERATURES IN THE DENDRITIC GROWTH LAYER WILL AID IN 20 OR 30 TO 1 SNOWFALL RATIOS ACROSS THE NORTHERN LARAMIE...SNOWY AND SIERRA MADRE RANGES ALONG WITH BLOWING SNOW DUE TO PROGGED SURFACE AND LOW LEVEL GRADIENTS. QUITE BLUSTERY AND COLD BASED ON PROGGED GRADIENTS. LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY... THERE IS GOOD CONSENSUS WITH THE 00Z MEDIUM RANGE MODEL GUIDANCE... PARTICULARLY WITH THE UPPER LEVEL FEATURES. A BROAD TROUGH OVER THE CENTRAL/EASTERN CONUS WILL GRADUALLY SHIFT EAST THROUGH THE END OF THE WEEK. THE EASTERN PACIFIC RIDGE WILL MOVE ONSHORE FRIDAY...AND BE LOCATED EAST OF THE ROCKIES ON SUNDAY. THE NEXT PACIFIC TROUGH WILL QUICKLY FOLLOW ON ITS HEELS SUNDAY NIGHT... REPLACED BY RIDGING FOR MONDAY. A SERIES OF WEAK SHORTWAVES IN THE NORTHWEST FLOW ALOFT WILL PRODUCE PERIODS OF LIGHT TO MODERATE SNOW WEDNESDAY NIGHT AND THURSDAY. THE OROGRAPHICALLY FAVORED SNOWY/SIERRA MADRE RANGES WILL BENEFIT...WITH ANOTHER FOOT OF SNOW EXPECTED. THE NORTHERN LARAMIE RANGE MAY RECEIVE UP TO A HALF FOOT OF SNOW AS WELL...WITH AN INCH OR LESS FOR THE PLAINS. IT WILL BE SEASONABLY COOL DURING THIS PERIOD WITH 700MB TEMPERATURES FROM -6 TO -10C. A MORE ZONAL FLOW ALOFT AND 700MB TEMPERATURES RISING TO AROUND 0C WILL EQUATE TO WELL ABOVE NORMAL TEMPERATURES FOR FRIDAY THROUGH MONDAY. A WEAK SHORTWAVE TROUGH PUSHING SOUTHEAST ACROSS THE REGION MAY BRING SOME LIGHT SNOW TO THE MOUNTAINS FRIDAY...OTHERWISE DRY CONDITIONS WILL PREVAIL. IT WILL BE BREEZY FOR THE MAJORITY OF THE LONG TERM...ESPECIALLY ACROSS SOUTHEAST WYOMING. && FIRE WEATHER... NO FIRE WEATHER CONCERNS DUE TO EXPECTED HUMIDITIES. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...WINTER STORM WARNING UNTIL 6 PM THURSDAY FOR WYZ112-WYZ114. WINTER WEATHER ADVISORY UNTIL 6 PM THURSDAY FOR WYZ113. WINTER WEATHER ADVISORY UNTIL 6 AM TUESDAY FOR WYZ103. NE...NONE. && $$ SHORT TERM/FIRE WEATHER...RUBIN LONG TERM...JAMSKI
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1041 PM MST TUE JAN 29 2013 .AVIATION... LIGHT SNOW SHOWERS IN THE VCNTY OF BOTH KCOS AND KPUB ARE EXPECTED TO COME TO AN END AROUND 09Z...WITH VFR CONDITIONS THEN EXPECTED THROUGH WEDNESDAY. WEDNESDAY AFTERNOON SOME BREEZY WEST TO NORTHWEST WINDS WILL BE POSSIBLE AT BOTH KCOS AND KPUB. EXPECTING KALS TO HAVE VFR CONDITIONS FOR THE NEXT 24 HOURS...WITH SOME BREEZY WESTERLY WINDS POSSIBLE WEDNESDAY AFTERNOON. && .PREV DISCUSSION... /ISSUED 302 PM MST TUE JAN 29 2013/ SHORT TERM... (TONIGHT AND WEDNESDAY) SNOW HAS BEEN WINDING DOWN ACROSS THE SOUTHEAST MOUNTAINS/I-25 CORRIDOR AS FOCUS FOR HEAVIER SNOW SHIFTS EASTWARD ACROSS THE PLAINS AHEAD OF THE MAIN UPPER TROF AXIS. SNOWFALL REPORTS THAT HAVE COME IN SO FAR HAVE INDICATED 2 TO 5 INCHES ACROSS THE LOWER EASTERN SLOPES OF THE SE MTS AND ADJACENT I-25 CORRIDOR. GOBBLERS KNOB WEB CAM IN SOUTHERN PROWERS COUNTY STARTING TO PICK UP SOME HEAVIER SNOW AS OF 2 PM...WITH GROUND NEARLY SNOW COVERED. FOCUS FOR HEAVIER SNOW WILL CONTINUE TO SHIFT SOUTH AND EASTWARD THROUGH THE LATE AFTERNOON AND EARLY EVENING. STILL THINKING GENERALLY 1-3 INCHES OF SNOWFALL FOR THE SOUTHEAST PLAINS GENERALLY TO THE SOUTH AND EAST OF KLHX. THE HEAVIEST WILL FALL ALONG THE NORTHERN SLOPES OF THE RATON MESA AND ACROSS BACA COUNTY. WHILE 18Z NAM CONTINUES TO DEPICT A BAND OF HEAVIER SNOW AMOUNTS OF 1 TO 3 INCHES ACROSS BACA/LAS ANIMAS...THE RAP HAS BACKED OFF ON THIS AND NOW PLACES THE BAND WELL TO THE SOUTH OF THE AREA. HRRR ALSO APPEARS TO HAVE BACKED OFF ON SNOW AMOUNTS ACROSS BACA COUNTY...SO WILL HOLD OFF ON ISSUING ANY HIGHLIGHTS AT THIS POINT AND STICK WITH THE GENERALLY 1-3 INCH AMOUNTS. WITH INSTABILITY STILL IN PLACE WITHIN THE TROF AXIS...THERE STILL COULD BE SOME LINGERING SNOW SHOWERS BEHIND THE TROF AXIS THROUGH THE EVENING...THUS WILL KEEP SCATTERED POPS IN AND NEAR THE MOUNTAINS UNTIL 06Z. MEANWHILE...ALTHOUGH HEAVIER SNOW WILL BE TAPERING OFF...NORTHWESTERLY OROGRAPHICS AND INCREASING WINDS ALOFT ON THE BACK SIDE OF THE UPPER TROF WILL KEEP WIDESPREAD LIGHT TO MODERATE SNOW GOING ALONG THE SAWATCH AND MOSQUITO RANGES THROUGH THE NIGHT...WITH THE WIND CAUSING SOME AREAS OF BLOWING SNOW. WITH TEMPERATURES FALLING INTO THE NEGATIVE READINGS OVERNIGHT...MAY ALSO SEE SOME WIND CHILL ADVISORY READINGS IN THE -25 TO -34 DEGREE RANGE. PREVIOUS SHIFT ISSUED A LONG DURATION WINTER WEATHER ADVISORY FOR THIS AREA...AND THIS STILL LOOKS GOOD...THOUGH HIGHEST IMPACT MAY BE DUE TO MORE BLOWING SNOW INITIALLY. WILL ADD MENTION OF THE WIND CHILL VALUES TO THE UPDATED WSW. MAY ALSO SEE WIND CHILL ADVISORY VALUES ACROSS THE HIGHER ELEVATIONS OF THE EASTERN SAN JUAN AND LA GARITA MOUNTAINS...THOUGH GIVEN THE SPOTTY NATURE WILL HOLD OFF ON ISSUING A WIND CHILL ADVISORY AT THIS POINT. TRAILING SHORTWAVE ENERGY DROPPING IN ON WEDNESDAY SHOULD ENHANCE SNOWFALL AGAIN ACROSS THE CENTRAL MOUNTAINS WEDNESDAY AFTERNOON. SHOULD SEE 24 HOUR ACCUMULATIONS OF 2 TO 8 INCHES THROUGH WEDNESDAY AFTERNOON FOR THIS AREA. ELSEWHERE WX WILL BE PRIMARILY DRY. GUSTY NORTHWEST 20-40 MPH WINDS WILL MIX DOWN INTO THE LOWER ELEVATIONS AND ADJACENT I-25 CORRIDOR WEDNESDAY AFTERNOON WHERE GUSTS TO AROUND 20-30 MPH WILL BE POSSIBLE. SNOW COVER WOULD BODE FOR KEEPING TEMPERATURES ON THE COOL SIDE OF GUIDANCE TOMORROW...THOUGH WITH THE WINDS AND SOME MIXING...THEY SHOULD MANAGE TO WARM ABOVE FREEZING ACROSS MOST OF THE PLAINS. LEANED MAX TEMPS TOWARDS THE COOLER SIDE OF GUIDANCE FOR NOW. MOUNTAIN AREAS WILL SEE HIGHS GENERALLY IN THE TEENS AND 20S...WITH SOME LOWER 30S ACROSS THE VALLEY AREAS. -KT LONG TERM... (WEDNESDAY NIGHT THROUGH TUESDAY) WEDNESDAY NIGHT AND THURSDAY...BRISK NW FLOW ALOFT CONTINUES ACROSS THE REGION THROUGH THURSDAY...WITH MODELS AGREEING ON KEEPING A NEARLY CONSTANT THREAT OF LIGHT TO MODERATE PCPN OVER THE CENT MTS THROUGH THE EVE. THOUGH NEW SNOW AMOUNTS WILL ACCUMULATE TO 12 TO 16 INCHES BY THURSDAY AFTN...ANOTHER REAL CONCERN WILL BE THE STRONG WINDS ALOFT THAT WILL BE EXPERIENCED ACROSS THE HIGHER TERRAIN. A 100 KT CORE OF THE UPPER JET NOSES INTO THE NW QUAD OF COLORADO THROUGH WEDNESDAY NIGHT...BEFORE MOVING EAST AND WINDS WEAKEN BY MIDDAY THURSDAY. THEREFORE...ONGOING WINTER WX ADV FOR THE HIGHER ELEVATIONS OF LAKE AND CHAFFEE COUNTIES LOOKS GOOD. MAX TEMPS ON THURSDAY ARE EXPECTED TO REBOUND INTO THE 50S FOR THE PLAINS...30S AND 40S FOR THE HIGH VALLEYS. FRIDAY AND SATURDAY...TEMPORARY RIDGING ACROSS THE DESERT SW AND COLORADO TO START THE WEEKEND...WITH DRY AND MILD CONDITIONS EXPECTED. MODELS DO INDICATE A MINOR UPPER DISTURBANCE ROLLING ACROSS THE ROCKY MT REGION...BUT CONTINUE TO KEEP THIS FEATURE JUST NORTH OF THE CWA AND FEEL THAT THE ONLY EFFECT WILL BE AN INCREASE IN HIGH LEVEL CLOUDINESS. WINDS REMAIN SOMEWHAT LIGHT...SO NO APPRECIABLE CHANGE IN THE TEMPS IS EXPECTED. SUNDAY THROUGH TUESDAY...AN UPPER LOW PRES SYSTEM JUST OFF THE S CA COAST WILL START PUSHING A PLUME OF WARMER PACIFIC MOISTURE UP ACROSS AZ AND THE 4 CORNERS STARTING ON SUNDAY. AT THE SAME TIME...AN UPPER DISTURBANCE DROPPING DOWN ACROSS MT AND WY WILL ACT UPON THIS MOISTURE TAP AND SQUEEZE OUT SOME ISOLATED SHOWERS ALONG THE CONTDVD LATE SUNDAY. AS THIS FEATURE MOVES EAST AND OUT OF THE AREA MONDAY...PCPN CHANCE DIMINISH. HOWEVER...LATE MONDAY THE LOW OFF THE WEST COAST STARTS TO FILL AND MOVE ONSHORE...BRINGING A SHOT FOR PCPN ONCE AGAIN TO THE CONTDVD STARTING TUESDAY MORNING. 27 AVIATION... VFR CIGS ACROSS THE TAF SITES WILL GRADUALLY DIMINISH THROUGH THE EVENING. THERE COULD BE A LIGHT SNOW SHOWER IN THE VICINITY OF KCOS THIS EVENING...THOUGH CHANCE LOOKS TOO REMOTE TO WARRANT INCLUSION IN THE TAF AT THIS POINT. WINDS WILL DECREASE TO UNDER 6 KTS AT KPUB AND KALS OVERNIGHT...THOUGH KCOS MAY CONTINUE TO SEE SOME ENHANCED NORTH WINDS IN THE 5-10 KT RANGE THROUGH THE NIGHT. MEANWHILE...IFR TO LIFR CIGS AND VIS IN -SHSN WILL CONTINUE ALONG THE CONTDVD...PARTICULARLY ACROSS THE CENTRAL MTS...RESULTING IN WIDESPREAD MTN OBSCURATIONS. MVFR TO BRIEFLY IFR CIGS WILL CONTINUE ACROSS THE SOUTHEAST PLAINS THROUGH EARLY EVENING BEFORE THE SNOW BAND PUSHES SOUTHEAST OF THE AREA OVERNIGHT. ON WEDNESDAY...VFR CIGS/VIS EXPECTED FOR THE TAF SITES...WITH SOME BREEZY WEST TO NW WINDS 10-15 KTS POSSIBLE AT KCOS AND KPUB DURING THE AFTERNOON. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 5 PM MST THURSDAY FOR COZ058-060. && $$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
410 AM EST WED JAN 30 2013 .SHORT TERM /TODAY THROUGH THURSDAY NIGHT/... PRIMARY CONCERN IS THREAT AND TIMING OF SEVERE CONVECTION THIS AFTERNOON AND EARLY EVENING. VERY IMPRESSIVE STORM SYSTEM APPROACHING THE STATE THIS MORNING. WHILE FAVORABLE SIG TOR PARAMETER VALUES CURRENTLY CONFINED TO AREA CLOSER TO THE COAST BASED ON RAP ANALYSES...HAVE SEEN A FEW REPORTS OF WIND DAMAGE FURTHER NORTH OVER WRN TN AND NRN MS IN LOW CAPE AREAS. IF MODELS ARE TO BE BELIEVED...PARAMETERS SHOULD BE MORE FAVORABLE HERE THAN WHAT IS CURRENTLY SHOWN TO THE WEST. 00Z MODELS HAVE SLOWED TIMING OF MAIN LINE OF TSRA SOMEWHAT WITH NAM SLOWEST. 06Z NAM ALSO CONTINUING SLOWER TREND. LINE SHOULD MOVE INTO NW CORNER OF CWA AROUND 10AM... I-85 BY 3PM AND AHN-MCN-AMERICUS LINE BY 7PM AND EXITING SE CORNER OF CWA AROUND 10PM. INGREDIENTS STILL APPEAR SUFFICIENT FOR AT LEAST ISOLD AREAS OF WIND DMG OR BRIEF TORNADOES. AS OFTEN THE CASE...06Z NAM MLCAPE SHOWING MORE INSTABILITY THAN OTHER MODELS WITH VALUES AROUND 400-700 J/KG. 00Z GFS HAS 200-400 J/KG OVER ALL BUT NE GA. VERTICAL WIND SHEAR WILL BE VERY STRONG. 0-1KM BULK SHEAR 40-50KTS SEEN ON GFS AND NAM. FAVORABLE CIN...LCL AND DEEP LAYER SHEAR YIELDING DECENT SIG TOR PARAMETER VALUES...1-2 WITH GFS AND 2-5 ON NAM. THIS VALUES ARE HIGHER THAN PREV SVR EVENT ON DEC 26 WHEN WE SAW 3 WEAK TORNADOES IN MIDDLE GA. WINDS STILL SHOULD KEEP MOST OF AREA IN ADV CRITERIA TODAY AND THIS EVENING. HAVE EXTENDED WIND ADV TIL MIDNIGHT. HIGH WIND WARNING CRITERIA NOT QUITE BEING MET IN LATEST MODEL GRIDS...BUT VERY CLOSE. WITH WET SOILS DEVELOPING QUICKLY THIS AFTERNOON...HAVE CONTINUED WIND WARNING THRU 6PM...AFTER WHICH TIME LLJ WILL SHIFT EAST OF THE NE GA MOUNTAINS. HEAVY RAIN WILL ALSO BE SIGNIFICANT THREAT. AGREE WITH LATEST HPC GUIDANCE WHICH HAS BUMPED UP EVENT TOTAL PRECIP TO 1 TO 2 INCHES WITH SOME AREAS OF NE GA APPROACHING 2.5 INCHES...DUE TO SLOWER TIMING AND PROGRESSION OF TSRA. SFC DEWPOINTS HAVE BEEN HIGHER THAN FCST LAST SEVERAL HOURS AS WELL. BASED ON LATEST GRIDDED FFG AND QPF...HAVE EXPANDED FLOOD WATCH SOUTH TO AREAS NORTH OF A FRANKLIN TO ROSWELL TO CLEVELAND LINE. FINALLY...ANOTHER LOW AMPLITUDE SHORT WAVE PROGGED TO MOVE ALONG LONG WAVE TROUGH OVER TN VALLEY THURS NIGHT. WITH COLD AIR IN PLACE...ESP ALOFT...COULD SEE SOME FLURRIES OR VERY LIGHT SNOW SHOWERS. NO IMPACTS EXPECTED. SNELSON .LONG TERM /FRIDAY THROUGH TUESDAY/... EXTENDED MODELS IN FAIRLY GOOD AGREEMENT THROUGH THE LONG TERM...WITH LONG WAVE UPPER-LEVEL TROUGH SITUATED OVER THE EASTERN U.S. THOUGH EARLY NEXT WEEK. GENERALLY...NORTHWEST FLOW WILL PERSIST OVER THE REGION...AND MODELS CONTINUE TO ADVERTISE A SERIES OF UPPER LEVEL SHORT WAVES IMPACTING THE AREA AS A RESULT. THE FIRST DISTURBANCE OCCURS AT THE TAIL END OF THE SHORT TERM PERIODS...AND WHAT MOISTURE QUICKLY DISSIPATES INTO THE LONG TERM EARLY FRIDAY. THE SECOND DISTURBANCE LOOKS TO APPROACH THE AREA LATE SATURDAY AND REMAIN ACROSS FAR NORTH GEORGIA EARLY SUNDAY...WITH SLIGHTLY MORE MOISTURE AVAILABLE THAN THE PREVIOUS SHORTWAVE. FOR NOW...WITH THE LATEST MODEL TIMING FOR THIS SYSTEM...LOOKS LIKE IT WILL PRIMARILY BE RAIN...WITH SOME POSSIBILITY OF A RAIN-SNOW MIX INTO SUNDAY MORNING. HAVE GENERALLY GONE WITH SLIGHT CHANCE POPS...AND HAVE KEPT NO ACCUMULATIONS FOR NORTH GEORGIA. HAVE SCALED BACK POPS SLIGHTLY FOR THE THIRD SHORT WAVE EXPECTED MONDAY NIGHT INTO TUESDAY. LATEST MODEL RUNS ARE LESS ENTHUSIASTIC WITH THE FRONTAL SUPPORT...AND THEREFORE LESS AGGRESSIVE WITH MOISTURE AND PRECIP POTENTIAL. HAVE CONTINUED WITH SLIGHT CHANCE POPS MONDAY NIGHT AND TUESDAY...AND QUICKLY DROP POPS OFF INTO TUESDAY NIGHT. BELANGER && .FIRE WEATHER... AS DRY AIR PLUNGES IN BEHIND FRONT...HUMIDITY PROGGED TO DROP TO 22 TO 25 PCT FOR A FEW HOURS THURS AFTERNOON OVER MIDDLE GA. WITH 1 TO 2 INCHES OF RAIN EXPECTED TODAY...FUELS ARE EXPECTED TO BE TOO WET TO REQUIRE ANY FIRE DANGER STATEMENTS. SNELSON && .AVIATION... 06Z UPDATE... MAIN CONCERN IS TIMING OF TSRA THIS AFTERNOON. WELL DEFINED LINE OF TSRA WILL MOVE THRU FROM WEST TO EAST...IMPACTING ATL METRO AIRPORTS AROUND 18Z-22Z. SHOULD SEE WIDESPREAD -SHRA DEVELOPING A FEW HOURS BEFORE THEN AND POSSIBLY CONTINUING AFTER LINE OF TSRA HAS MOVED THRU. OTHER CONCERN TODAY IS STRONG CROSSWINDS AT AIRPORTS WITH E-W RUNWAY CONFIGURATION...INCLUDING KATL WHERE CROSSWIND COMPONENT GUSTS 16Z-22Z COULD APPROACH 30KTS. IFR CIGS LIKELY AT MOST AIRPORTS FROM 09Z THRU 14Z THOUGH MAY BE TOO WARM OVER MIDDLE GA AIRPORTS FOR CIGS TO GET DOWN TO IFR. CIGS WILL IMPROVE AFTER LINE OF TSRA MOVES THRU...AROUND 22Z AT ATL...THEN CLEAR ENTIRELY AFTER 06Z-09Z THURS. //ATL CONFIDENCE...06Z UPDATE... MEDIUM CONFIDENCE ON IFR CIGS THIS MORNING AND TSRA TIMING. HIGH CONFIDENCE ON ALL OTHER ELEMENTS. SNELSON && .PRELIMINARY POINT TEMPS/POPS... ATHENS 71 38 50 33 / 100 100 5 5 ATLANTA 67 35 49 33 / 100 60 5 5 BLAIRSVILLE 61 32 43 27 / 100 60 5 20 CARTERSVILLE 67 34 47 31 / 100 40 5 10 COLUMBUS 72 38 56 39 / 100 70 5 5 GAINESVILLE 63 35 47 32 / 100 70 5 10 MACON 73 39 55 33 / 90 100 5 5 ROME 68 33 48 31 / 100 40 5 10 PEACHTREE CITY 68 36 51 32 / 100 60 5 5 VIDALIA 80 46 59 36 / 70 90 0 5 && .FFC WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR THE FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BARTOW...BIBB...BLECKLEY... BUTTS...CARROLL...CATOOSA...CHATTAHOOCHEE...CHATTOOGA... CHEROKEE...CLARKE...CLAYTON...COBB...COWETA...CRAWFORD...CRISP... DADE...DEKALB...DODGE...DOOLY...DOUGLAS...EMANUEL...FAYETTE... FLOYD...FORSYTH...GLASCOCK...GORDON...GREENE...GWINNETT...HALL... HANCOCK...HARALSON...HARRIS...HEARD...HENRY...HOUSTON... JACKSON...JASPER...JEFFERSON...JOHNSON...JONES...LAMAR... LAURENS...MACON...MADISON...MARION...MERIWETHER...MONROE... MONTGOMERY...MORGAN...MUSCOGEE...NEWTON...NORTH FULTON... OCONEE...OGLETHORPE...PAULDING...PEACH...PIKE...POLK...PULASKI... PUTNAM...ROCKDALE...SCHLEY...SOUTH FULTON...SPALDING...STEWART... SUMTER...TALBOT...TALIAFERRO...TAYLOR...TELFAIR...TOOMBS... TREUTLEN...TROUP...TWIGGS...UPSON...WALKER...WALTON...WARREN... WASHINGTON...WEBSTER...WHEELER...WHITFIELD...WILCOX...WILKES... WILKINSON. HIGH WIND WARNING UNTIL 6 PM EST THIS EVENING FOR THE FOLLOWING ZONES: DAWSON...FANNIN...GILMER...LUMPKIN...MURRAY...PICKENS... TOWNS...UNION...WHITE. FLOOD WATCH FROM 9 AM EST THIS MORNING THROUGH THIS EVENING FOR THE FOLLOWING ZONES: BARTOW...CATOOSA...CHATTOOGA...CHEROKEE... COBB...DADE...DAWSON...FANNIN...FLOYD...FORSYTH...GILMER... GORDON...HARALSON...LUMPKIN...MURRAY...NORTH FULTON...PAULDING... PICKENS...POLK...TOWNS...UNION...WALKER...WHITE...WHITFIELD. WIND ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT EST TONIGHT FOR THE FOLLOWING ZONES: DAWSON...FANNIN...GILMER...LUMPKIN... MURRAY...PICKENS...TOWNS...UNION...WHITE. && $$ SHORT TERM...SNELSON LONG TERM....BELANGER AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
403 AM EST WED JAN 30 2013 .SYNOPSIS... HIGH PRESSURE WILL MOVE EAST TODAY AS STRONG WEATHER SYSTEM WITH STRONG COLD FRONT MOVE TOWARD THE REGION. BOTH MOISTURE AND WINDS WILL INCREASE WITH SHOWERS AND POSSIBLE AFTERNOON AND EVENING THUNDERSTORMS. WARM AIR TODAY WITH HIGHS UP AROUND 80. AFTER THE COLD FRONT PASSES TONIGHT...IT WILL TURN SHARPLY COLDER AND HIGHS THURSDAY WILL BE ALMOST 30 DEGREES COLDER. HIGH PRESSURE FRIDAY AND SATURDAY WILL PROVIDE DRY CHILLY WEATHER WITH BELOW NORMAL TEMPERATURES. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THROUGH MID MORNING...UPPER RIDGE TEMPORARILY HOLDING SHOWERS TO THE WEST AND NORTH. BUT RIDGE WILL WEAKEN AND MOVE EAST FOR THE REMAINDER OF THE NIGHT. CAE 88D JUST SHOWING SOME LIGHT SHOWERS NORTHWEST OF HERE IN THE GSP CWA. REGIONAL RADARS SHOWING SHOWER COVERAGE INCREASING IN GEORGIA. ACTIVITY WILL MOVE TO THE EAST THOUGH AS INDICATED BY RUC13. RUC MODEL HAS SHOWERS ENTERING WESTERN PART OF CAE CWA IN THE CSRA 10-12Z TIME FRAME. JUST SHOWERS THIS MORNING BUT THUNDERSTORMS ARE POSSIBLE CLOSER TO MID DAY` OVER THE REGION. INCREASING WIND FLOW AT SURFACE WITH SOUTHERLY WINDS 10-20 MPH. TEMPERATURES HOLDING ABOUT 64-65 DEGREES WITH INCREASING INSTABILITY BUT LIS STILL POSITIVE AT +3/+4/. TODAY...DEEP TROUGH TO THE WEST WILL SHIFT EASTWARD ACROSS THE MISSISSIPPI VALLEY AND PUSH A COLD FRONT INTO THE CAROLINAS LATE THIS AFTERNOON. AHEAD OF THIS SYSTEM...MOISTURE FLUX WILL INCREASE WITH GFS MODEL PWS INCREASING TO 1.60 INCHES. SIGNIFICANT 500MB HEIGHT FALLS WILL PRECEDE THE UPPER TROUGH AS THE RIGHT ENTRANCE REGION OF AN ASSOCIATED 150KT UPPER JET SHIFTS OVER THE SOUTHEAST STATES. FORECAST MODELS ARE IN AGREEMENT ALSO SHOWING A VERY STRONG...NEARLY 75KT 850MB JET SHIFTING OVER THE CAROLINAS DURING THE AFTERNOON. TEMPERATURES ARE EXPECTED TO SURGE TO AROUND 80 IN THE AFTERNOON WITH DEWPOINTS HOLDING IN THE LOWER 60S. INSTABILITY APPEARS TO BE LIMITED BUT WIND SHEAR WILL BE EXTREME AND THIS LOOKS LIKE A CLASSIC HIGH SHEAR LOW CAPE (HSLC) ENVIRONMENT. DUE TO THE STRONG WINDS AND POTENTIAL FOR STRONG WINDS TO REACH THE SURFACE AND WILL CONTINUE THE WIND ADVISORY FROM 11AM WEDNESDAY THROUGH 6 AM THURSDAY MORNING. ALL OF THESE FACTORS LEAD TO REASONABLY HIGH CONFIDENCE THAT THERE WILL BE A LINE OF CONVECTION ALONG OR JUST AHEAD OF THE FRONT THAT WILL BE CAPABLE OF MIXING DOWN VERY STRONG WINDS TO THE SURFACE. SPC CONTINUES TO OUTLOOK THE AREA IN A SLIGHT RISK FOR SEVERE WEATHER WITH DAMAGING WINDS BEING THE MAIN THREAT. TIME FRAME IS LATE AFTERNOON INTO THE EVENING HOURS. WILL CONTINUE CATEGORICAL POPS FROM WEST TO EAST LATE AFTERNOON THROUGH EARLY EVENING. PRECIPITATION AMOUNTS SHOULD BE LIMITED BY SPEED OF THE SYSTEM BUT COULD SEE A QUARTER TO THREE QUARTERS OF AN INCH ACROSS THE AREA. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... STRONG UPPER DYNAMICS WILL CONTINUE DURING THE EVENING HOURS UNTIL FRONTAL PASSAGE NEAR 9-10 PM TIME FRAME THIS EVENING. THE STRONG LLJ OF AROUND 75KT WILL CONTINUE AS WELL. LOCAL MODELS INDICATE POSSIBLY A SQUALL LINE 6-8 PM TIME FRAME AND CONDITIONS MAY BE FAVORABLE FOR STRONG WINDS TO REACH THE SURFACE LATE IN THE AFTERNOON OR IN THE EVENING BEFORE THE COLD FRONT MOVES THROUGH. 20KM NAM IS GIVING LIS AROUND -2 DURING THIS TIME BUT NAM BUFR SOUNDING HAS VERY LOW CAPES BELOW 200 J/KG AT THIS TIME AND THIS LOOKS LIKE A CLASSIC HIGH SHEAR LOW CAPE ENVIRONMENT. SPC CONTINUES SLIGHT RISK OF SEVERE STORMS FOR THE AREA WITH THE MAIN THREAT FROM DAMAGING WINDS. CONTINUING WITH CATEGORICAL POPS FROM WEST TO EAST THROUGH EARLY EVENING. AGAIN...PRECIPITATION AMOUNTS SHOULD BE LIMITED BY SPEED OF THE SYSTEM BUT COULD SEE A QUARTER TO THREE QUARTERS OF AN INCH ACROSS THE AREA. BEHIND THE FRONT...COOL HIGH PRESSURE WILL BUILD INTO THE REGION LATE WEDNESDAY NIGHT AND THURSDAY AS SKIES CLEAR FROM WEST TO EAST AND TEMPERATURES FALL INTO THE 40S. HIGH PRESSURE WILL RESIDE OVER THE AREA THROUGH THE END OF THE PERIOD WITH A GRADIENT IN MAX TEMPS THU/FRI FROM LOWER 50S NORTH TO UPPER 50S SOUTH. ANOTHER SHORTWAVE WILL CROSS THE OHIO VALLEY TO OUR NORTH ON FRIDAY AND BRING A DRY COLD FRONT THROUGH BY FRIDAY EVENING...LEADING TO BELOW NORMAL OVERNIGHT LOWS FRIDAY NIGHT IN THE 20S. && .LONG TERM /SATURDAY THROUGH TUESDAY/... THE EXTENDED FORECAST WILL FEATURE AN ACTIVE WEATHER PATTERN AS MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT SHOWING A MEAN NORTHWESTERLY 500MB FLOW WITH A SERIES OF SHORTWAVES MOVING OVER THE REGION. SURFACE HIGH PRESSURE WILL BE IN PLACE SATURDAY WITH WESTERLY UPPER FLOW...RESULTING IN MOSTLY SUNNY SKIES AND NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES. THE FIRST SHORTWAVE TO CROSS THE REGION WILL TRACK SOUTHEASTWARD ACROSS THE OHIO VALLEY INTO THE MID ATLANTIC REGION SATURDAY NIGHT...PUSHING A COLD FRONT THROUGH THE FORECAST AREA BY SUNDAY MORNING. MOISTURE WILL BE LIMITED WITH THIS FRONT AND LITTLE IF ANY PRECIPITATION IS EXPECTED. MOST OF THE COLD AIR WILL REMAIN NORTH OF THE MIDLANDS AS HIGH PRESSURE BUILDS INTO THE AREA SUNDAY AND MONDAY. FAIR SKIES AND ABOVE NORMAL TEMPERATURES ARE EXPECTED SUNDAY AND MONDAY WITH HIGHS IN THE UPPER 50S TO LOWER 60S AND LOWS IN THE 30S. A SECOND SHORTWAVE TROUGH WILL FOLLOW A SIMILAR PATH ACROSS THE OHIO VALLEY TO THE MID ATLANTIC IN NORTHWESTERLY UPPER FLOW ON MONDAY NIGHT INTO TUESDAY. AGAIN A COLD FRONT WILL PUSH THROUGH THE REGION SOMETIME TUESDAY MORNING. MOISTURE WILL BE LIMITED WITH THIS FRONT AS WELL AND PRECIPITATION CHANCES ARE EXPECTED TO BE LOW. && .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/... EXPECT IFR CEILINGS WILL DEVELOP OVERNIGHT BECAUSE OF HIGH LOW- LEVEL MOISTURE AHEAD OF THE APPROACHING WEAK WARM FRONT. THE NAM AND GFS MOS ARE IN GOOD AGREEMENT INDICATING IFR CEILINGS. FOG SHOULD BE LIMITED BY INCREASING BOUNDARY LAYER WIND. LOW-LEVEL WIND SHEAR WILL OCCUR. THE MODELS INDICATE WINDS INCREASING TO AROUND 40 KNOTS AT 2000 FEET. THE WARM FRONT SHOULD LIFT NORTH OF THE AREA EARLY WEDNESDAY WITH STRONG HEATING AND MIXING AHEAD OF THE APPROACHING COLD FRONT. CEILINGS SHOULD IMPROVE. WINDS WILL BE ON THE INCREASE AHEAD OF THE APPROACHING COLD FRONT. EXPECT A LINE OF SHOWERS WILL DEVELOP AHEAD OF THE FRONT. THERE MAY ALSO BE THUNDERSTORMS. AN AVERAGE OF THE NAM AND GFS SUPPORTS SHOWERS BECOMING LIKELY BEGINNING AROUND 22Z. WINDS WILL BE STRONG AND GUSTY ESPECIALLY NEAR ANY SHOWERS OR THUNDERSTORMS. WINDS OVER 30 KNOTS MAY OCCUR. EXTENDED AVIATION OUTLOOK...SHOWERS AND POSSIBLY THUNDERSTORMS WILL CONTINUE INTO WEDNESDAY NIGHT. WINDS OVER 30S KNOTS MAY OCCUR ESPECIALLY NEAR ANY SHOWERS AND THUNDERSTORMS. IT WILL BE BREEZY BEHIND THE COLD FRONT THURSDAY. NO SIGNIFICANT IMPACTS EXPECTED DURING THE REST OF THE OUTLOOK PERIOD. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...WIND ADVISORY FROM 11 AM THIS MORNING TO 6 AM EST THURSDAY FOR SCZ015-016-018-020>022-025>031-035>038-041. GA...WIND ADVISORY FROM 11 AM THIS MORNING TO 6 AM EST THURSDAY FOR GAZ040-063>065-077. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
248 AM EST WED JAN 30 2013 .SYNOPSIS... HIGH PRESSURE OVER THE REGION WILL MOVE EAST OVERNIGHT. A STRONG COLD FRONT WILL APPROACH FROM THE WEST WEDNESDAY AND SWEEP THROUGH THE AREA WEDNESDAY EVENING. WINDS WILL BE STRONG AHEAD OF THE FRONT WEDNESDAY AFTERNOON AND SEVERE WEATHER IS POSSIBLE AS THE FRONT PASSES. HIGH PRESSURE WILL RETURN FOR THURSDAY AND FRIDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... UPPER RIDGE TEMPORARILY HOLDING SHOWERS TO THE WEST AND NORTH. BUT RIDGE WILL WEAKEN AND MOVE EAST FOR THE REMAINDER OF THE NIGHT. CAE 88D JUST SHOWING SOME LIGHT SHOWERS NORTHWEST OF HERE IN THE GSP CWA. REGIONAL RADARS SHOWING SHOWER COVERAGE INCREASING IN GEORGIA. ACTIVITY WILL MOVE TO THE EAST THOUGH AS INDICATED BY RUC13. RUC MODEL HAS SHOWERS ENTERING WESTERN PART OF CAE CWA IN THE CSRA 10-12Z TIME FRAME. JUST SHOWERS THIS MORNING BUT THUNDERSTORMS ARE POSSIBLE CLOSER TO MID DAY` OVER THE REGION. INCREASING WIND FLOW AT SURFACE WITH SOUTHERLY WINDS 10-20 MPH. TEMPERATURES HOLDING ABOUT 64-65 DEGREES WITH INCREASING INSTABILITY BUT LIS STILL POSITIVE AT +3/+4/. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/... DEEP TROUGH OVER THE INTERMOUNTAIN WEST TODAY WILL SHIFT EASTWARD ACROSS THE MISSISSIPPI VALLEY ON WEDNESDAY WHICH WILL PUSH A COLD FRONT INTO THE CAROLINAS LATE WEDNESDAY AFTERNOON AND CROSS THE REGION WEDNESDAY NIGHT. AHEAD OF THIS SYSTEM...THE UPPER RIDGE AXIS WILL SHIFT OFF THE COAST AS THE SURFACE RIDGE WEAKENS WITH DEEP SOUTH TO SOUTHWESTERLY FLOW. SIGNIFICANT 500MB HEIGHT FALLS WILL PRECEDE THE UPPER TROUGH AS THE RIGHT ENTRANCE REGION OF AN ASSOCIATED 150KT UPPER JET SHIFTS OVER THE SOUTHEASTERN STATES LATE WEDNESDAY AFTERNOON AND EVENING. FORECAST MODELS ARE IN AGREEMENT ALSO SHOWING A VERY STRONG...NEARLY 75KT 850MB JET SHIFTING OVER THE CAROLINAS DURING THE AFTERNOON AND EARLY EVENING HOURS. TEMPERATURES ARE EXPECTED TO SURGE INTO THE MID TO UPPER 70S WITH DEWPOINTS PUSHING INTO THE LOWER TO MID 60S. PWAT VALUES ARE FORECAST TO APPROACH 1.60-1.70 INCHES JUST AHEAD OF THE FRONT...WHICH IS ABOVE THE 99TH PERCENTILE. INSTABILITY APPEARS TO BE LIMITED BUT WIND SHEAR WILL BE EXTREME AND THIS LOOKS LIKE A CLASSIC HIGH SHEAR LOW CAPE (HSLC) ENVIRONMENT. DUE TO THE STRONG WINDS AND POTENTIAL FOR STRONG WINDS TO REACH THE SURFACE...AFTER COORDINATION WITH SURROUNDING OFFICES...WILL ISSUE A WIND ADVISORY FROM 11AM WEDNESDAY THROUGH 6 AM THURSDAY MORNING. ALL OF THESE FACTORS LEAD TO REASONABLY HIGH CONFIDENCE THAT THERE WILL BE A LINE OF CONVECTION ALONG OR JUST AHEAD OF THE FRONT THAT WILL BE CAPABLE OF MIXING DOWN VERY STRONG WINDS TO THE SURFACE. SPC CONTINUES TO OUTLOOK THE AREA IN A SLIGHT RISK FOR SEVERE WEATHER WITH DAMAGING WINDS BEING THE MAIN THREAT. TIME FRAME FOR THE CONVECTION TO MOVE THROUGH THE FORECAST AREA LOOKS TO BE BETWEEN 22Z-06Z. CONTINUING WITH CATEGORICAL POPS FROM WEST TO EAST LATE AFTERNOON THROUGH EARLY EVENING WEDNESDAY. PRECIPITATION AMOUNTS SHOULD BE LIMITED BY SPEED OF THE SYSTEM BUT COULD SEE A QUARTER TO THREE QUARTERS OF AN INCH ACROSS THE AREA. BEHIND THE FRONT...COOL HIGH PRESSURE WILL BUILD INTO THE REGION LATE WEDNESDAY NIGHT AND THURSDAY AS SKIES CLEAR FROM WEST TO EAST AND TEMPERATURES FALL INTO THE 40S. HIGH PRESSURE WILL RESIDE OVER THE AREA THROUGH THE END OF THE PERIOD WITH A GRADIENT IN MAX TEMPS THU/FRI FROM LOWER 50S NORTH TO UPPER 50S SOUTH. ANOTHER SHORTWAVE WILL CROSS THE OHIO VALLEY TO OUR NORTH ON FRIDAY AND BRING A DRY COLD FRONT THROUGH BY FRIDAY EVENING...LEADING TO BELOW NORMAL OVERNIGHT LOWS FRIDAY NIGHT IN THE 20S. && .LONG TERM /SATURDAY THROUGH TUESDAY/... THE EXTENDED FORECAST WILL FEATURE AN ACTIVE WEATHER PATTERN AS MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT SHOWING A MEAN NORTHWESTERLY 500MB FLOW WITH A SERIES OF SHORTWAVES MOVING OVER THE REGION. SURFACE HIGH PRESSURE WILL BE IN PLACE SATURDAY WITH WESTERLY UPPER FLOW...RESULTING IN MOSTLY SUNNY SKIES AND NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES. THE FIRST SHORTWAVE TO CROSS THE REGION WILL TRACK SOUTHEASTWARD ACROSS THE OHIO VALLEY INTO THE MID ATLANTIC REGION SATURDAY NIGHT...PUSHING A COLD FRONT THROUGH THE FORECAST AREA BY SUNDAY MORNING. MOISTURE WILL BE LIMITED WITH THIS FRONT AND LITTLE IF ANY PRECIPITATION IS EXPECTED. MOST OF THE COLD AIR WILL REMAIN NORTH OF THE MIDLANDS AS HIGH PRESSURE BUILDS INTO THE AREA SUNDAY AND MONDAY. FAIR SKIES AND ABOVE NORMAL TEMPERATURES ARE EXPECTED SUNDAY AND MONDAY WITH HIGHS IN THE UPPER 50S TO LOWER 60S AND LOWS IN THE 30S. A SECOND SHORTWAVE TROUGH WILL FOLLOW A SIMILAR PATH ACROSS THE OHIO VALLEY TO THE MID ATLANTIC IN NORTHWESTERLY UPPER FLOW ON MONDAY NIGHT INTO TUESDAY. AGAIN A COLD FRONT WILL PUSH THROUGH THE REGION SOMETIME TUESDAY MORNING. MOISTURE WILL BE LIMITED WITH THIS FRONT AS WELL AND PRECIPITATION CHANCES ARE EXPECTED TO BE LOW. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... EXPECT IFR CEILINGS WILL DEVELOP OVERNIGHT BECAUSE OF HIGH LOW- LEVEL MOISTURE AHEAD OF THE APPROACHING WEAK WARM FRONT. THE NAM AND GFS MOS ARE IN GOOD AGREEMENT INDICATING IFR CEILINGS. FOG SHOULD BE LIMITED BY INCREASING BOUNDARY LAYER WIND. LOW-LEVEL WIND SHEAR WILL OCCUR. THE MODELS INDICATE WINDS INCREASING TO AROUND 40 KNOTS AT 2000 FEET. THE WARM FRONT SHOULD LIFT NORTH OF THE AREA EARLY WEDNESDAY WITH STRONG HEATING AND MIXING AHEAD OF THE APPROACHING COLD FRONT. CEILINGS SHOULD IMPROVE. WINDS WILL BE ON THE INCREASE AHEAD OF THE APPROACHING COLD FRONT. EXPECT A LINE OF SHOWERS WILL DEVELOP AHEAD OF THE FRONT. THERE MAY ALSO BE THUNDERSTORMS. AN AVERAGE OF THE NAM AND GFS SUPPORTS SHOWERS BECOMING LIKELY BEGINNING AROUND 22Z. WINDS WILL BE STRONG AND GUSTY ESPECIALLY NEAR ANY SHOWERS OR THUNDERSTORMS. WINDS OVER 30 KNOTS MAY OCCUR. EXTENDED AVIATION OUTLOOK...SHOWERS AND POSSIBLY THUNDERSTORMS WILL CONTINUE INTO WEDNESDAY NIGHT. WINDS OVER 30S KNOTS MAY OCCUR ESPECIALLY NEAR ANY SHOWERS AND THUNDERSTORMS. IT WILL BE BREEZY BEHIND THE COLD FRONT THURSDAY. NO SIGNIFICANT IMPACTS EXPECTED DURING THE REST OF THE OUTLOOK PERIOD. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...WIND ADVISORY FROM 11 AM THIS MORNING TO 6 AM EST THURSDAY FOR SCZ015-016-018-020>022-025>031-035>038-041. GA...WIND ADVISORY FROM 11 AM THIS MORNING TO 6 AM EST THURSDAY FOR GAZ040-063>065-077. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
346 AM CST WED JAN 30 2013 .MESOSCALE DISCUSSION... 240 PM CST THE THREAT FOR HEAVY RAIN DEVELOPING AND POSSIBLY A COUPLE SEVERE STORMS CONTINUES. THE LATEST HAND ANALYSIS PLACES THE COLD FRONT JUST PAST THE MISSISSIPPI RIVER IN NORTHWEST IL WITH A SUBTLE PRE-FRONTAL TROUGH FROM JUST EAST OF ROCKFORD SOUTH TOWARD PEORIA. THIS PRE- FRONTAL TROUGH DOES HAVE AN INSTABILITY PLUME AIDED BY LOW TO MID 60S TEMPERATURES...AND LOW-LEVEL CAPE IS ANALYZED NEAR 100 J/KG WITH AROUND 300-500 J/KG OF SURFACE-BASED CAPE. THIS INSTABILITY THOUGH IS NOT LINING UP WITH ANY GREAT STORM ACTIVITY. SATELLITE AND RADAR TRENDS SHOW THAT A LARGE SWATH OF RAIN HAS EXPANDED FROM MO NORTHEAST THROUGH WESTERN IL AND SOUTHERN WI...STABILIZING MUCH OF THAT AREA. AT THE FRONT EDGE OF THIS...NEAR THE PRE-FRONTAL TROUGH...MORE CONVECTIVE-LIKE SHOWERS ARE PRESENT. THAT CONVECTION ON THE ILX RADAR HAS STRUGGLED TO BECOME WELL-DEFINED AND HAS MORE OF A QUASI-LINEAR MUSHY LOOK RIGHT NOW. LIGHTNING HAS BEEN SOMEWHAT SPORADIC AND REALLY HAS ONLY BEEN SEEN IN THE CLUSTER THAT IS NEARING CHICAGO...POSSIBLY ASSOCIATED WITH A WARM AIR ADVECTION FLANK AHEAD OF THE SYSTEM. OVERALL THE TREND HAS BEEN SLIGHTLY DOWN WITH NO LOCAL STORMS APPROACHING SEVERE LIMITS...AND A FEW 30-37 KT GUSTS OBSERVED. AT THIS TIME...IT REMAINS QUITE MARGINAL FOR SEVERE WEATHER AND MAY CONTINUE TO THROUGH MUCH OF THE AFTERNOON AS NO IMMEDIATE STRONG IMPULSES UPSTREAM ARE EVIDENT. TOWARD SUNSET AND INTO THIS EVENING...AREAS ALONG AND EAST OF I-55 WILL REMAIN FAVORED FOR STORM ACTIVITY ON THE NOSE OF AN INCREASING LOW LEVEL JET AND JUST MORE IMPROVED OVERALL FORCING. EXPLICIT CONVECTIVE MODELS AGREE THIS AREA WILL BE UNDER SOME STRONGER ACTIVITY THIS EVENING...BUT WHETHER THAT IS TO THE LIMITS TO FLIRT WITH SEVERE IS LOW CONFIDENCE. THE FORECAST DCAPE DOES INCREASE TO AROUND 400-500 J/KG ON THE NAM AND THE LOW-LEVEL SHEAR/HELICITY REMAINS HIGH IN THE STRONG ATMOSPHERIC WINDS. THIS MAY END UP BEING OUR BEST...ALBEIT NARROW WINDOW FOR SEVERE WEATHER. HEAVY RAIN REMAINS THE PRIMARY POTENTIAL HAZARD. WHILE IT IS A QUASI- LINEAR MUSHY LOOK RIGHT NOW...RAINFALL RATES ARE LIKELY VERY EFFICIENT IN ANY ACTIVITY AND WILL CONTINUE AS SUCH LATE THIS AFTERNOON INTO TONIGHT. A PERSISTENT FOCUS IS SEEN IN THE RAP AND NAM FORECASTS AS DEEP LAYER MOISTURE CONVERGENCE FURTHER INCREASES TONIGHT AS THE UPPER TROUGH INCHES EASTWARD. WIDESPREAD RAINFALL AMOUNTS OF ONE TO TWO AND A HALF INCHES LOOK LIKELY...WITH POTENTIALLY THE HIGHER END AMOUNTS BEING WIDESPREAD. WITH MUCH OF THIS GOING TOWARD RUNOFF...AT LEAST LOCALIZED PONDING TO POSSIBLE FLOODING WILL BE LIKELY. MTF && .DISCUSSION... 318 PM CST SHORT TERM...REST OF TODAY THROUGH WEDNESDAY NIGHT... FOR HEADLINES...KEPT FLOOD WATCH AS IS AND NO WINTER HEADLINES ARE EXPECTED AT THIS TIME. A DEEP TROUGH LIES ACROSS THE WESTERN US WITH ITS AXIS OVER THE GREAT PLAINS...WHILE A SURFACE LOW IS OVER ONTARIO. THE SURFACE LOWS COLD FRONT EXTENDS FROM THE LOW THROUGH CENTRAL WI TO ALONG THE MISSISSIPPI RIVER...AND IT IS SLOWLY MAKING ITS WAY INTO WESTERN IL. THE TEMPERATURE GRADIENT ACROSS THE FRONT IS RATHER IMPRESSIVE WITH 60 DEGREES IN PERU IL AND 38 DEGREES IN OTTUMWA IA...WITH JUST 176 MILES BETWEEN THE TWO CITIES. SHOWERS AND THUNDERSTORMS HAVE SPREAD INTO NORTHERN IL AHEAD OF THE COLD FRONT AND WILL CONTINUE TO SPREAD ACROSS THE CWA THIS AFTERNOON/EARLY EVENING. INDIVIDUAL CELLS HAVE BEEN CLOCKED AT 50-60 KT MOVING FROM THE SOUTHWEST TO THE NORTHEAST. SEVERE STORMS ARE STILL POSSIBLE THIS AFTERNOON...FOR MORE INFORMATION ON THE SEVERE WEATHER OUTLOOK AND RELATED PARAMETERS PLEASE SEE THE MESOSCALE DISCUSSION ABOVE. PWAT VALUES WILL BE IN EXCESS OF 1-1.5 INCHES THIS AFTERNOON/EVENING WITH DEW POINTS CURRENTLY IN THE UPPER 50S TO LOW 60S FALLING OVERNIGHT. FLOW THROUGHOUT THE ATMOSPHERIC COLUMN IS ROUGHLY PARALLEL TO THE FRONT WHICH WILL INHIBIT THE FRONT FROM RAPIDLY PROGRESSING THROUGH THE CWA. TRAINING WILL ALSO BECOME AN ISSUE ALONG THE FRONT ALLOWING FOR IMPRESSIVE RAIN TOTALS. THE UPPER LEVEL JET STRETCHES FROM TEXAS THROUGH MINNESOTA BEFORE CURVING TOWARD QUEBEC. THE RIGHT JET ENTRANCE REGION LIES OVER SOUTHWEST WI/NORTHWEST IL ALMOST COLLOCATED WITH THE FRONT WHICH WILL CONTINUE TO SUPPORT THUNDERSTORM AND SHOWER FORMATION. BASED ON WHAT HAS PASSED OVER THE OFFICE THIS AFTERNOON...SOME OF THESE SHOWERS/STORMS WILL PRODUCE BRIEF INTENSE DOWNPOURS. THE JET AND FRONT CONTINUE ACROSS THE CWA TONIGHT WITH THE SOUTHERN JET STREAKS LEFT EXIT REGION POSSIBLY COUPLING WITH THE FRONT. AS SUCH EXPECTING PERIODS OF HEAVY RAIN TO CONTINUE OVERNIGHT. WHEN ALL IS SAID AND DONE...THINKING 1.5-2.5 INCHES OF RAIN ARE POSSIBLE ACROSS THE AREA. LOCALLY HIGHER AMOUNTS ARE CERTAINLY POSSIBLE. QUICKLY CHECKING THE OFFICES SOIL TEMPS...2 AND 4 INCHES BELOW THE SURFACE ARE ABOVE FREEZING AT 35 DEGREES WHILE 8 INCHES IS STILL FROZEN AT 27 DEGREES. AS SUCH EXPECTING PONDING OF WATER IN THE TYPICAL LOW LYING SPOTS...SINCE THE SOIL WILL NOT BE ABLE TO TAKE IN AS MUCH WATER AS USUAL. THEREFORE MADE NO ADJUSTMENTS TO THE FLOOD WATCH. TEMPS WILL BEGIN TO FALL OVERNIGHT WITH LOWS IN THE LOW 30S NEAR RFD TO ARND 50 NEAR RENSSELAER. WEDNESDAY... TEMPS WILL CONTINUE TO FALL WEDNESDAY MORNING WITH PRECIP TRANSITIONING TO SNOW AS A SWATH OF MOISTURE ASSOCIATED WITH THE 700 MB LOW SURGES NORTH. SOUNDINGS INDICATE A BRIEF PERIOD OF SLEET IS POSSIBLE DURING THE TRANSITION BUT NOT EXPECTING ANY SIGNIFICANT SLEET ACCUMULATION. EXPECTING AREAS AROUND RFD TO CHANGE OVER TO SNOW BEFORE 8AM...CHICAGO AROUND 3PM...AND NW INDIANA 4-6PM. FOR SNOW TOTALS...EXPECTING THE HIGHEST TOTALS IN FAR NW IL IN WINNEBAGO AND OGLE COUNTIES. THE NAM IS MUCH MORE EXCITED THAN THE GFS ABOUT THE SNOW POTENTIAL BUT BOTH MODELS SHOW THE SAME SET UP THAT IS FAVORABLE FOR MESOSCALE SNOW BANDS. 850-700 MB FRONTOGENESIS MOVES OVER NW IL/E IA EARLY WEDNESDAY MORNING WITH EPV VALUES BELOW 0 JUST ABOVE IT...INDICATING LOCALIZED INTENSE FORCING AND SYMMETRIC INSTABILITY. HOWEVER EXPECTING TEMPS TO BE ABOVE FREEZING AT THIS POINT. THE FRONTOGENESIS AND INSTABILITY SHIFT EASTWARD THROUGH THE MORNING AND THEN WEAKEN AFTER NOON. THE LEFT JET EXIT REGION OF THE UPPER LEVEL JET WILL ALSO BE OVER NORTHERN IL THROUGH WEDNESDAY AFTERNOON SO SYNOPTIC-SCALE LIFT SHOULD NOT BE AN ISSUE. WHILE MESOSCALE BANDS OF RAIN OR SNOW ARE VERY LIKELY TOMORROW...THESE FEATURES ARE HARD TO PINPOINT EVEN THIS FAR OUT. THEREFORE WENT WITH 3-5 INCHES OF SNOW OVER WINNEBAGO AND OGLE COUNTIES TOMORROW...BUT THIS NUMBER COULD EASILY BE HIGHER IF A BAND OF SNOW SETS UP. THE BIG QUESTIONS ARE WILL THE BEST FORCING ALIGN WITH SNOW OR RAIN...HOW LONG WILL THE FORCING LAST...AND WHERE WILL THE MESOSCALE BAND SET UP. AS MENTIONED BEFORE...THE FRONTOGENESIS WEAKENS AND STABILITY INCREASES IN THE AFTERNOON AS THE SNOW SPREADS ACROSS THE REST OF THE CWA. SO INTENSE MESOSCALE BANDS ARE NOT AS LIKELY...BUT FORCING FROM THE UPPER LEVEL JET STILL LOOKS FAVORABLE FOR A LITTLE SNOW. AS SUCH EXPECTING 1 TO 3 INCHES OF SNOW ACROSS BOONE AND MCHENRY COUNTIES...AND THEN AN INCH OR LESS EVERYWHERE ELSE. SNOW ENDS FROM WEST TO EAST...WITH NO SNOW EXPECTED AFTER MIDNIGHT ON WEDNESDAY. TEMPS CONTINUE TO TUMBLE TO THE TEENS OR SINGLE DIGITS WEDNESDAY NIGHT. WINDS 20-25 MPH WITH GUSTS UP TO 30 MPH SLOWLY WEAKEN OVERNIGHT...BUT EXPECTING WIND CHILLS TO BE BTWN 1 AND -10. JEE EXTENDED PERIOD...THURSDAY THROUGH TUESDAY... MAIN FORECAST CONCERN IN EXTENDED PERIOD DEALS WITH REINFORCEMENT OF ARCTIC COLD THURSDAY NIGHT/FRIDAY...AND THE POTENTIAL FOR LIGHT SNOW FRIDAY NIGHT/SATURDAY WITH A COUPLE CLIPPER-TYPE SYSTEMS ON THE BACK SIDE OF THE RETREATING LOW LEVEL COLD AIR. MEDIUM RANGE GUIDANCE APPEARS TO BE IN GOOD AGREEMENT AT THE START OF THE PERIOD THURSDAY MORNING...WITH DEEP SURFACE LOW LIFTING NORTHEAST ACROSS EASTERN QUEBEC AND DEEP UPPER LEVEL TROUGH ACROSS MUCH OF EASTERN NORTH AMERICA. ALL OF THE GLOBAL MODELS DEPICT ANOTHER STRONG SHORT WAVE DIGGING SOUTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES REGION THROUGH THE DAY... ACCOMPANIED BY A STRONG PUSH OF COLD ARCTIC AIR WITH 850 MB TEMPS OF -22 TO -24 C MOVING INTO THE CWA BY THURSDAY EVENING. MODEL SOUNDINGS AND TIME/HEIGHT SERIES INDICATE DRY MID/UPPER LEVELS AHEAD OF THIS DIGGING SHORT WAVE...WITH MODEL GENERATED QPF LIMITED TO THE MID/LOWER MISSOURI RIVER VALLEY INTO THE LOWER OHIO VALLEY THURSDAY AFTERNOON AND EVENING...THE COMBINATION OF DIGGING VORT...COLD ADVECTION WITH VERY COLD ARCTIC AIR...AND RELATIVELY MOIST LOW LEVELS ALL POINT TO THE POTENTIAL FOR AT LEAST SOME FLURRIES ACROSS THE FORECAST AREA THURSDAY AFTERNOON/EVENING. TEMPS...WHICH SHOULD ONLY TOP OUT IN THE MID TEENS NORTH AND LOWER 20S SOUTH AFTER WEDNESDAYS COLD FRONT...SHOULD EASILY FALL TO AROUND/BELOW ZERO ACROSS NORTH CENTRAL IL BY SUNRISE FRIDAY AND TO PERHAPS THE LOW POSITIVE SINGLE DIGITS ACROSS THE SOUTH WITH STRONG LOW LEVEL COLD ADVECTION THURSDAY NIGHT. HAVE TRENDED COLDER TOWARD THE 00Z GEFS MOS...AND A FEW DEGREES BELOW THAT AROUND ROCKFORD. THIS MAY NOT BE COLD ENOUGH ESPECIALLY IF SIGNIFICANT SNOW PACK IS IN PLACE AFTER WEDNESDAY. WINDS SHOULD REMAIN BLUSTERY ESPECIALLY IN THE EVENING WITH THE ENHANCED GRADIENT TO THE EAST OF THE CANADIAN HIGH BUILDING SOUTHEAST THROUGH THE PLAINS...SUPPORTING WIND CHILLS -10 TO -20 F OVERNIGHT. THE MID-LEVEL SHORT WAVE TROUGH AXIS IS PROGGED TO MOVE OFF TO THE SOUTHEAST OF THE FORECAST AREA EARLY FRIDAY MORNING...WITH FAIRLY STRONG HEIGHT RISES DEVELOPING IN ITS WAKE. COLD SURFACE HIGH PRESSURE CENTER WILL CONTINUE TO PUSH SOUTHEAST THROUGH THE LOWER OHIO VALLEY INTO TENNESSEE BY EVENING. CORE OF THE COLDEST AIR WILL SHIFT OFF TO THE EAST/SOUTHEAST BY AFTERNOON...THOUGH COLD MORNING START AND SHALLOW MIXED LAYER BENEATH SUBSIDENCE INVERSION WILL ALLOW ONLY MARGINAL MODERATION OF TEMPS AT THE SURFACE. HAVE ALSO TRENDED COLDER WITH MAXES FRIDAY TOWARD COLDER GFS/GEFS MOS NUMBERS. NORTHERN EXTENT OF SURFACE RIDGE AXIS MOVES ACROSS THE CWA FRIDAY EVENING...WITH WARM ADVECTION ALREADY DEVELOPING ON THE WESTERN PERIPHERY OF THE RETREATING LOW LEVEL COLD AIR DOME. WITH NORTHWEST FLOW ALOFT ON THE BACK SIDE OF THE DEPARTING LONG-WAVE UPPER TROUGH THIS SETS THE STAGE FOR A COUPLE OF MODEST SHORT WAVES TO BRING A COUPLE POTENTIAL PERIODS OF LIGHT SNOW TO THE REGION FRIDAY NIGHT AND SATURDAY. ECMWF/GFS 12Z RUNS REMAIN IN FAIRLY GOOD AGREEMENT IN DEVELOPING LIGHT QPF ACROSS THE AREA WITH A WEAK SURFACE LOW MOVING ACROSS NORTHERN ILLINOIS SATURDAY. UPPER JET CORE THEN SHIFTS SLOWLY EAST/NORTHEAST ACROSS THE NORTHERN/CENTRAL GREAT LAKES SATURDAY NIGHT...AS HIGH PRESSURE RIDGE MOVES ACROSS THE REGION THROUGH SUNDAY. WITH COLD CORE OF UPPER TROUGH OFF TO THE EAST...TEMPS MODERATE BACK TO MORE SEASONABLE LEVELS SATURDAY (MID-UPPER 20S) AND PERHAPS A BIT ABOVE (30S) SUNDAY AS WINDS SHIFT SOUTH IN THE AFTERNOON WEST OF THE RIDGE AXIS. MODERATION LOOKS TO CONTINUE MONDAY AS ECMWF/GFS REMAIN IN GOOD AGREEMENT IN TAKING AN AREA OF SURFACE LOW PRESSURE NORTH OF THE CWA ACROSS MN/WI. DRY HIGH PRESSURE BLOCKS MOISTURE RETURN FROM THE SOUTH FOR THE MOST PART... WITH NEXT CHANCE OF ORGANIZED PRECIP OCCURRING WITH THE COLD FRONT ASSOCIATED WITH THIS LOW MONDAY/MONDAY NIGHT...AND MAINLY ACROSS THE SOUTHEASTERN CWA. GEM MEANWHILE DURING THIS PERIOD BECOMES A COLD OUTLIER...WITH CONSISTENT ECMWF/GFS SOLUTIONS FAVORED AT THIS DISTANCE. THIS WOULD INDICATE COOLER/SEASONAL TEMPS RETURN TUESDAY. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * CONTINUED LIGHT RAIN PERSISTING TO AROUND SUNRISE. * LIGHT RAIN SHOWERS MIXING/SWITCHING TO LIGHT SNOW LATE MORNING TO EARLY AFTERNOON. * ENDING OF LIGHT SNOW FIRST PART OF THIS EVENING. * PREVAILING IFR...OCCASIONALLY MVFR...BECOMING PREVAILING MVFR LATE AFTERNOON. * WINDS BECOMING NORTH AROUND SUNRISE THEN NORTHWEST BY AFTERNOON. * WINDS INCREASE DURING THE MORNING WITH GUSTS GENERALLY 25-30KT FROM LATE MORNING THROUGH EVENING. TRS //DISCUSSION...UPDATED 09Z... MAIN AREA OF RAIN STARTING TO MOVE NORTHEASTWARD OUT OF NORTHEAST IL AS A SHORT WAVE LIFTS RAPIDLY NORTH-NORTHEAST ACROSS EASTERN IA. RAIN WILL CONTINUE TO BECOME LESS WIDESPREAD/MORE SHOWERY ACROSS THE LOCAL AREA BY DAWN AS A DRY SLOT...QUITE EVIDENT IN BOTH WATER VAPOR SATELLITE AND COMPOSITE RADAR LOOPS...PUNCHES ACROSS NORTHERN IL THIS MORNING. TRS PREVIOUS DISCUSSION...UPDATED 06Z... LARGE NE-SW BAND OF HEAVIER RAIN HAS BEEN SHIFTING EAST DURING THE EVENING AND AS OF LATE EVENING WAS EAST HAD PROGRESSED TO THE EAST OF ORD AND MDW. A BROAD BAND OF MAINLY LIGHT RAIN EXTENDED WESTWARD FROM THE HEAVIER RAIN BACK TO SOUTH CENTRAL WI...WEST CENTRAL IL AND SOUTH CENTRAL MO AS ADDITIONAL SHORT WAVES LIFT NORTHEAST AHEAD OF THE MAIN UPPER TROUGH WITH AN AXIS ALONG A SOUTHWEST ONTARIO TO NORTHERN TX LINE. THIS TROUGH AXIS IS PROGGED TO REACH SOUTHWEST WI...NORTHEAST MO AND WESTERN AR BY 18Z AS IS SHOWN CONTINUING EAST AND ACROSS THE LOCAL AREA DURING THE LATE AFTERNOON AND EARLY EVENING. EXPECTED PRECIPITATION TO PERSIST OVERNIGHT AND ALL THE WAY INTO EARLY EVENING. THE RAIN WILL MIX/SWITCH TO LIGHT SNOW AROUND MIDDAY AS A SOMEWHAT ILL DEFINED SURFACE LOW CURRENTLY OVER NORTHEAST IL/FAR SOUTHERN LAKE MI/NORTHWEST IN PROGRESSES NORTHEASTWARD THROUGH THE GREAT LAKES AND INTO ONTARIO BY 18Z... SPREADING COLD AIR ACROSS THE AREA AS THE TRAILING COLD FRONT PUSHES FURTHER EASTWARD. BETWEEN AN INCREASING PRESSURE GRADIENT SPREADING WEST TO EAST MIDDAY THROUGH EARLY EVENING NORTH-NORTHWEST TO NORTHWEST WINDS WILL INCREASE...AND STRENGTHENING OF THE COLD AIR ADVECTION DURING THIS TIME SUSTAINED WINDS OF 15-20KT AND GUSTS 25-30KT ARE EXPECTED MIDDAY AND WELL INTO TONIGHT. CEILINGS WILL STAY BELOW 010 INTO EARLY AFTERNOON THEN RISE A BIT TO THE 015-020 RANGE AS DEW POINT DEPRESSIONS INCREASE TO A FEW DEGREES IN THE COLD AIR. CEILINGS ARE FORECAST TO RISE TO AT OR ABOVE 020 IN THE EARLY TO MID EVENING AS THIS IS WHEN THE LIGHT SNOW IS EXPECTED TO END AND LOW LEVEL DEW POINT DEPRESSIONS INCREASE. TRS //ORD AND MDW CONFIDENCE...UPDATED 09Z... * MEDIUM CONFIDENCE IN TIMING OF SHITHC OVER FROM RAIN TO SNOW. * MEDIUM CONFIDENCE IN WIND TRENDS. * MEDIUM CONFIDENCE IN CEILING AND VISIBILITY TRENDS. TRS //OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z... THURSDAY...CHANCE OF FLURRIES IN THE AFTERNOON/EVENING. MVFR CIGS POSSIBLE. WEST WINDS GUSTING TO 25-30KT. FRIDAY...VFR EARLY. CHANCE OF SNOW WITH MVFR CIGS/VIS OVERNIGHT. SATURDAY...CHANCE OF SNOW WITH MVFR CIGS/VIS EARLY...THE VFR OVERNIGHT. SUNDAY...VFR. WX NIL. MONDAY...SLIGHT CHANCE RAIN/SNOW. MVFR CIGS/VIS POSSIBLE. KREIN && .MARINE... 345 AM CST RAPIDLY CHANGING WINDS ARE ONGOING ACROSS THE LAKE AS A TROUGH OF LOW PRESSURE SITUATED ACROSS THE REGION CONTINUES TO SLOWLY WORK ITS WAY TO THE NORTHEAST TODAY. AS THIS OCCURS...THE PRESSURE GRADIENT WILL BECOME MORE ORGANIZED WITH STRONG NORTHERLY WINDS PICKING UP THROUGHOUT THE DAY. EXPECT NORTHERLY WINDS TO 30 KT THIS MORNING TO CONTINUE INCREASING TO GALES TODAY AND THIS EVENING...WITH NOW A PORTION OF THE NEARSHORE WATERS OBSERVING THESE NORTHERLY GALES. HAVE MAINTAINED A MENTION OF GALES TO 40 KT FOR A PERIOD LATER TODAY...AS WINDS TURN MORE TOWARDS THE NORTHWEST AND WEST LATER TONIGHT. AS THIS OCCURS...EXPECT WINDS TO ALSO DIMINISH TO 30 KT THURSDAY MORNING BUT WITH THESE WESTERLY WINDS TO 30 KT CONTINUING TO AT LEAST FRIDAY MORNING. ALTHOUGH NOT LIKELY AT THIS TIME...THERE DOES APPEAR TO BE A BRIEF WINDOW OF SOME WEST/NORTHWEST GALES DURING THE OVERNIGHT HOURS THURSDAY NIGHT. WILL NEED TO CONTINUE TO MONITOR THIS GALE POTENTIAL THURSDAY NIGHT...ALSO AS STRONGER WESTERLY WINDS IN THE NEARSHORE PERSIST AT LEAST THROUGH LATE THURSDAY NIGHT. RODRIGUEZ && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023- ILZ032-ILZ033-ILZ039 UNTIL 4 AM WEDNESDAY. WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ008...9 AM WEDNESDAY TO 4 PM WEDNESDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 4 AM WEDNESDAY. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM WEDNESDAY TO 9 AM THURSDAY. SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 4 AM FRIDAY. GALE WARNING...LMZ743-LMZ744-LMZ745...4 PM WEDNESDAY TO 4 AM THURSDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
345 AM CST WED JAN 30 2013 .MESOSCALE DISCUSSION... 240 PM CST THE THREAT FOR HEAVY RAIN DEVELOPING AND POSSIBLY A COUPLE SEVERE STORMS CONTINUES. THE LATEST HAND ANALYSIS PLACES THE COLD FRONT JUST PAST THE MISSISSIPPI RIVER IN NORTHWEST IL WITH A SUBTLE PRE-FRONTAL TROUGH FROM JUST EAST OF ROCKFORD SOUTH TOWARD PEORIA. THIS PRE- FRONTAL TROUGH DOES HAVE AN INSTABILITY PLUME AIDED BY LOW TO MID 60S TEMPERATURES...AND LOW-LEVEL CAPE IS ANALYZED NEAR 100 J/KG WITH AROUND 300-500 J/KG OF SURFACE-BASED CAPE. THIS INSTABILITY THOUGH IS NOT LINING UP WITH ANY GREAT STORM ACTIVITY. SATELLITE AND RADAR TRENDS SHOW THAT A LARGE SWATH OF RAIN HAS EXPANDED FROM MO NORTHEAST THROUGH WESTERN IL AND SOUTHERN WI...STABILIZING MUCH OF THAT AREA. AT THE FRONT EDGE OF THIS...NEAR THE PRE-FRONTAL TROUGH...MORE CONVECTIVE-LIKE SHOWERS ARE PRESENT. THAT CONVECTION ON THE ILX RADAR HAS STRUGGLED TO BECOME WELL-DEFINED AND HAS MORE OF A QUASI-LINEAR MUSHY LOOK RIGHT NOW. LIGHTNING HAS BEEN SOMEWHAT SPORADIC AND REALLY HAS ONLY BEEN SEEN IN THE CLUSTER THAT IS NEARING CHICAGO...POSSIBLY ASSOCIATED WITH A WARM AIR ADVECTION FLANK AHEAD OF THE SYSTEM. OVERALL THE TREND HAS BEEN SLIGHTLY DOWN WITH NO LOCAL STORMS APPROACHING SEVERE LIMITS...AND A FEW 30-37 KT GUSTS OBSERVED. AT THIS TIME...IT REMAINS QUITE MARGINAL FOR SEVERE WEATHER AND MAY CONTINUE TO THROUGH MUCH OF THE AFTERNOON AS NO IMMEDIATE STRONG IMPULSES UPSTREAM ARE EVIDENT. TOWARD SUNSET AND INTO THIS EVENING...AREAS ALONG AND EAST OF I-55 WILL REMAIN FAVORED FOR STORM ACTIVITY ON THE NOSE OF AN INCREASING LOW LEVEL JET AND JUST MORE IMPROVED OVERALL FORCING. EXPLICIT CONVECTIVE MODELS AGREE THIS AREA WILL BE UNDER SOME STRONGER ACTIVITY THIS EVENING...BUT WHETHER THAT IS TO THE LIMITS TO FLIRT WITH SEVERE IS LOW CONFIDENCE. THE FORECAST DCAPE DOES INCREASE TO AROUND 400-500 J/KG ON THE NAM AND THE LOW-LEVEL SHEAR/HELICITY REMAINS HIGH IN THE STRONG ATMOSPHERIC WINDS. THIS MAY END UP BEING OUR BEST...ALBEIT NARROW WINDOW FOR SEVERE WEATHER. HEAVY RAIN REMAINS THE PRIMARY POTENTIAL HAZARD. WHILE IT IS A QUASI- LINEAR MUSHY LOOK RIGHT NOW...RAINFALL RATES ARE LIKELY VERY EFFICIENT IN ANY ACTIVITY AND WILL CONTINUE AS SUCH LATE THIS AFTERNOON INTO TONIGHT. A PERSISTENT FOCUS IS SEEN IN THE RAP AND NAM FORECASTS AS DEEP LAYER MOISTURE CONVERGENCE FURTHER INCREASES TONIGHT AS THE UPPER TROUGH INCHES EASTWARD. WIDESPREAD RAINFALL AMOUNTS OF ONE TO TWO AND A HALF INCHES LOOK LIKELY...WITH POTENTIALLY THE HIGHER END AMOUNTS BEING WIDESPREAD. WITH MUCH OF THIS GOING TOWARD RUNOFF...AT LEAST LOCALIZED PONDING TO POSSIBLE FLOODING WILL BE LIKELY. MTF && .DISCUSSION... 318 PM CST SHORT TERM...REST OF TODAY THROUGH WEDNESDAY NIGHT... FOR HEADLINES...KEPT FLOOD WATCH AS IS AND NO WINTER HEADLINES ARE EXPECTED AT THIS TIME. A DEEP TROUGH LIES ACROSS THE WESTERN US WITH ITS AXIS OVER THE GREAT PLAINS...WHILE A SURFACE LOW IS OVER ONTARIO. THE SURFACE LOWS COLD FRONT EXTENDS FROM THE LOW THROUGH CENTRAL WI TO ALONG THE MISSISSIPPI RIVER...AND IT IS SLOWLY MAKING ITS WAY INTO WESTERN IL. THE TEMPERATURE GRADIENT ACROSS THE FRONT IS RATHER IMPRESSIVE WITH 60 DEGREES IN PERU IL AND 38 DEGREES IN OTTUMWA IA...WITH JUST 176 MILES BETWEEN THE TWO CITIES. SHOWERS AND THUNDERSTORMS HAVE SPREAD INTO NORTHERN IL AHEAD OF THE COLD FRONT AND WILL CONTINUE TO SPREAD ACROSS THE CWA THIS AFTERNOON/EARLY EVENING. INDIVIDUAL CELLS HAVE BEEN CLOCKED AT 50-60 KT MOVING FROM THE SOUTHWEST TO THE NORTHEAST. SEVERE STORMS ARE STILL POSSIBLE THIS AFTERNOON...FOR MORE INFORMATION ON THE SEVERE WEATHER OUTLOOK AND RELATED PARAMETERS PLEASE SEE THE MESOSCALE DISCUSSION ABOVE. PWAT VALUES WILL BE IN EXCESS OF 1-1.5 INCHES THIS AFTERNOON/EVENING WITH DEW POINTS CURRENTLY IN THE UPPER 50S TO LOW 60S FALLING OVERNIGHT. FLOW THROUGHOUT THE ATMOSPHERIC COLUMN IS ROUGHLY PARALLEL TO THE FRONT WHICH WILL INHIBIT THE FRONT FROM RAPIDLY PROGRESSING THROUGH THE CWA. TRAINING WILL ALSO BECOME AN ISSUE ALONG THE FRONT ALLOWING FOR IMPRESSIVE RAIN TOTALS. THE UPPER LEVEL JET STRETCHES FROM TEXAS THROUGH MINNESOTA BEFORE CURVING TOWARD QUEBEC. THE RIGHT JET ENTRANCE REGION LIES OVER SOUTHWEST WI/NORTHWEST IL ALMOST COLLOCATED WITH THE FRONT WHICH WILL CONTINUE TO SUPPORT THUNDERSTORM AND SHOWER FORMATION. BASED ON WHAT HAS PASSED OVER THE OFFICE THIS AFTERNOON...SOME OF THESE SHOWERS/STORMS WILL PRODUCE BRIEF INTENSE DOWNPOURS. THE JET AND FRONT CONTINUE ACROSS THE CWA TONIGHT WITH THE SOUTHERN JET STREAKS LEFT EXIT REGION POSSIBLY COUPLING WITH THE FRONT. AS SUCH EXPECTING PERIODS OF HEAVY RAIN TO CONTINUE OVERNIGHT. WHEN ALL IS SAID AND DONE...THINKING 1.5-2.5 INCHES OF RAIN ARE POSSIBLE ACROSS THE AREA. LOCALLY HIGHER AMOUNTS ARE CERTAINLY POSSIBLE. QUICKLY CHECKING THE OFFICES SOIL TEMPS...2 AND 4 INCHES BELOW THE SURFACE ARE ABOVE FREEZING AT 35 DEGREES WHILE 8 INCHES IS STILL FROZEN AT 27 DEGREES. AS SUCH EXPECTING PONDING OF WATER IN THE TYPICAL LOW LYING SPOTS...SINCE THE SOIL WILL NOT BE ABLE TO TAKE IN AS MUCH WATER AS USUAL. THEREFORE MADE NO ADJUSTMENTS TO THE FLOOD WATCH. TEMPS WILL BEGIN TO FALL OVERNIGHT WITH LOWS IN THE LOW 30S NEAR RFD TO ARND 50 NEAR RENSSELAER. WEDNESDAY... TEMPS WILL CONTINUE TO FALL WEDNESDAY MORNING WITH PRECIP TRANSITIONING TO SNOW AS A SWATH OF MOISTURE ASSOCIATED WITH THE 700 MB LOW SURGES NORTH. SOUNDINGS INDICATE A BRIEF PERIOD OF SLEET IS POSSIBLE DURING THE TRANSITION BUT NOT EXPECTING ANY SIGNIFICANT SLEET ACCUMULATION. EXPECTING AREAS AROUND RFD TO CHANGE OVER TO SNOW BEFORE 8AM...CHICAGO AROUND 3PM...AND NW INDIANA 4-6PM. FOR SNOW TOTALS...EXPECTING THE HIGHEST TOTALS IN FAR NW IL IN WINNEBAGO AND OGLE COUNTIES. THE NAM IS MUCH MORE EXCITED THAN THE GFS ABOUT THE SNOW POTENTIAL BUT BOTH MODELS SHOW THE SAME SET UP THAT IS FAVORABLE FOR MESOSCALE SNOW BANDS. 850-700 MB FRONTOGENESIS MOVES OVER NW IL/E IA EARLY WEDNESDAY MORNING WITH EPV VALUES BELOW 0 JUST ABOVE IT...INDICATING LOCALIZED INTENSE FORCING AND SYMMETRIC INSTABILITY. HOWEVER EXPECTING TEMPS TO BE ABOVE FREEZING AT THIS POINT. THE FRONTOGENESIS AND INSTABILITY SHIFT EASTWARD THROUGH THE MORNING AND THEN WEAKEN AFTER NOON. THE LEFT JET EXIT REGION OF THE UPPER LEVEL JET WILL ALSO BE OVER NORTHERN IL THROUGH WEDNESDAY AFTERNOON SO SYNOPTIC-SCALE LIFT SHOULD NOT BE AN ISSUE. WHILE MESOSCALE BANDS OF RAIN OR SNOW ARE VERY LIKELY TOMORROW...THESE FEATURES ARE HARD TO PINPOINT EVEN THIS FAR OUT. THEREFORE WENT WITH 3-5 INCHES OF SNOW OVER WINNEBAGO AND OGLE COUNTIES TOMORROW...BUT THIS NUMBER COULD EASILY BE HIGHER IF A BAND OF SNOW SETS UP. THE BIG QUESTIONS ARE WILL THE BEST FORCING ALIGN WITH SNOW OR RAIN...HOW LONG WILL THE FORCING LAST...AND WHERE WILL THE MESOSCALE BAND SET UP. AS MENTIONED BEFORE...THE FRONTOGENESIS WEAKENS AND STABILITY INCREASES IN THE AFTERNOON AS THE SNOW SPREADS ACROSS THE REST OF THE CWA. SO INTENSE MESOSCALE BANDS ARE NOT AS LIKELY...BUT FORCING FROM THE UPPER LEVEL JET STILL LOOKS FAVORABLE FOR A LITTLE SNOW. AS SUCH EXPECTING 1 TO 3 INCHES OF SNOW ACROSS BOONE AND MCHENRY COUNTIES...AND THEN AN INCH OR LESS EVERYWHERE ELSE. SNOW ENDS FROM WEST TO EAST...WITH NO SNOW EXPECTED AFTER MIDNIGHT ON WEDNESDAY. TEMPS CONTINUE TO TUMBLE TO THE TEENS OR SINGLE DIGITS WEDNESDAY NIGHT. WINDS 20-25 MPH WITH GUSTS UP TO 30 MPH SLOWLY WEAKEN OVERNIGHT...BUT EXPECTING WIND CHILLS TO BE BTWN 1 AND -10. JEE EXTENDED PERIOD...THURSDAY THROUGH TUESDAY... MAIN FORECAST CONCERN IN EXTENDED PERIOD DEALS WITH REINFORCEMENT OF ARCTIC COLD THURSDAY NIGHT/FRIDAY...AND THE POTENTIAL FOR LIGHT SNOW FRIDAY NIGHT/SATURDAY WITH A COUPLE CLIPPER-TYPE SYSTEMS ON THE BACK SIDE OF THE RETREATING LOW LEVEL COLD AIR. MEDIUM RANGE GUIDANCE APPEARS TO BE IN GOOD AGREEMENT AT THE START OF THE PERIOD THURSDAY MORNING...WITH DEEP SURFACE LOW LIFTING NORTHEAST ACROSS EASTERN QUEBEC AND DEEP UPPER LEVEL TROUGH ACROSS MUCH OF EASTERN NORTH AMERICA. ALL OF THE GLOBAL MODELS DEPICT ANOTHER STRONG SHORT WAVE DIGGING SOUTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES REGION THROUGH THE DAY... ACCOMPANIED BY A STRONG PUSH OF COLD ARCTIC AIR WITH 850 MB TEMPS OF -22 TO -24 C MOVING INTO THE CWA BY THURSDAY EVENING. MODEL SOUNDINGS AND TIME/HEIGHT SERIES INDICATE DRY MID/UPPER LEVELS AHEAD OF THIS DIGGING SHORT WAVE...WITH MODEL GENERATED QPF LIMITED TO THE MID/LOWER MISSOURI RIVER VALLEY INTO THE LOWER OHIO VALLEY THURSDAY AFTERNOON AND EVENING...THE COMBINATION OF DIGGING VORT...COLD ADVECTION WITH VERY COLD ARCTIC AIR...AND RELATIVELY MOIST LOW LEVELS ALL POINT TO THE POTENTIAL FOR AT LEAST SOME FLURRIES ACROSS THE FORECAST AREA THURSDAY AFTERNOON/EVENING. TEMPS...WHICH SHOULD ONLY TOP OUT IN THE MID TEENS NORTH AND LOWER 20S SOUTH AFTER WEDNESDAYS COLD FRONT...SHOULD EASILY FALL TO AROUND/BELOW ZERO ACROSS NORTH CENTRAL IL BY SUNRISE FRIDAY AND TO PERHAPS THE LOW POSITIVE SINGLE DIGITS ACROSS THE SOUTH WITH STRONG LOW LEVEL COLD ADVECTION THURSDAY NIGHT. HAVE TRENDED COLDER TOWARD THE 00Z GEFS MOS...AND A FEW DEGREES BELOW THAT AROUND ROCKFORD. THIS MAY NOT BE COLD ENOUGH ESPECIALLY IF SIGNIFICANT SNOW PACK IS IN PLACE AFTER WEDNESDAY. WINDS SHOULD REMAIN BLUSTERY ESPECIALLY IN THE EVENING WITH THE ENHANCED GRADIENT TO THE EAST OF THE CANADIAN HIGH BUILDING SOUTHEAST THROUGH THE PLAINS...SUPPORTING WIND CHILLS -10 TO -20 F OVERNIGHT. THE MID-LEVEL SHORT WAVE TROUGH AXIS IS PROGGED TO MOVE OFF TO THE SOUTHEAST OF THE FORECAST AREA EARLY FRIDAY MORNING...WITH FAIRLY STRONG HEIGHT RISES DEVELOPING IN ITS WAKE. COLD SURFACE HIGH PRESSURE CENTER WILL CONTINUE TO PUSH SOUTHEAST THROUGH THE LOWER OHIO VALLEY INTO TENNESSEE BY EVENING. CORE OF THE COLDEST AIR WILL SHIFT OFF TO THE EAST/SOUTHEAST BY AFTERNOON...THOUGH COLD MORNING START AND SHALLOW MIXED LAYER BENEATH SUBSIDENCE INVERSION WILL ALLOW ONLY MARGINAL MODERATION OF TEMPS AT THE SURFACE. HAVE ALSO TRENDED COLDER WITH MAXES FRIDAY TOWARD COLDER GFS/GEFS MOS NUMBERS. NORTHERN EXTENT OF SURFACE RIDGE AXIS MOVES ACROSS THE CWA FRIDAY EVENING...WITH WARM ADVECTION ALREADY DEVELOPING ON THE WESTERN PERIPHERY OF THE RETREATING LOW LEVEL COLD AIR DOME. WITH NORTHWEST FLOW ALOFT ON THE BACK SIDE OF THE DEPARTING LONG-WAVE UPPER TROUGH THIS SETS THE STAGE FOR A COUPLE OF MODEST SHORT WAVES TO BRING A COUPLE POTENTIAL PERIODS OF LIGHT SNOW TO THE REGION FRIDAY NIGHT AND SATURDAY. ECMWF/GFS 12Z RUNS REMAIN IN FAIRLY GOOD AGREEMENT IN DEVELOPING LIGHT QPF ACROSS THE AREA WITH A WEAK SURFACE LOW MOVING ACROSS NORTHERN ILLINOIS SATURDAY. UPPER JET CORE THEN SHIFTS SLOWLY EAST/NORTHEAST ACROSS THE NORTHERN/CENTRAL GREAT LAKES SATURDAY NIGHT...AS HIGH PRESSURE RIDGE MOVES ACROSS THE REGION THROUGH SUNDAY. WITH COLD CORE OF UPPER TROUGH OFF TO THE EAST...TEMPS MODERATE BACK TO MORE SEASONABLE LEVELS SATURDAY (MID-UPPER 20S) AND PERHAPS A BIT ABOVE (30S) SUNDAY AS WINDS SHIFT SOUTH IN THE AFTERNOON WEST OF THE RIDGE AXIS. MODERATION LOOKS TO CONTINUE MONDAY AS ECMWF/GFS REMAIN IN GOOD AGREEMENT IN TAKING AN AREA OF SURFACE LOW PRESSURE NORTH OF THE CWA ACROSS MN/WI. DRY HIGH PRESSURE BLOCKS MOISTURE RETURN FROM THE SOUTH FOR THE MOST PART... WITH NEXT CHANCE OF ORGANIZED PRECIP OCCURRING WITH THE COLD FRONT ASSOCIATED WITH THIS LOW MONDAY/MONDAY NIGHT...AND MAINLY ACROSS THE SOUTHEASTERN CWA. GEM MEANWHILE DURING THIS PERIOD BECOMES A COLD OUTLIER...WITH CONSISTENT ECMWF/GFS SOLUTIONS FAVORED AT THIS DISTANCE. THIS WOULD INDICATE COOLER/SEASONAL TEMPS RETURN TUESDAY. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * CONTINUED LIGHT RAIN PERSISTING TO AROUND SUNRISE. * LIGHT RAIN SHOWERS MIXING/SWITCHING TO LIGHT SNOW LATE MORNING TO EARLY AFTERNOON. * ENDING OF LIGHT SNOW FIRST PART OF THIS EVENING. * PREVAILING IFR...OCCASIONALLY MVFR...BECOMING PREVAILING MVFR LATE AFTERNOON. * WINDS BECOMING NORTH AROUND SUNRISE THEN NORTHWEST BY AFTERNOON. * WINDS INCREASE DURING THE MORNING WITH GUSTS GENERALLY 25-30KT FROM LATE MORNING THROUGH EVENING. TRS //DISCUSSION...UPDATED 09Z... MAIN AREA OF RAIN STARTING TO MOVE NORTHEASTWARD OUT OF NORTHEAST IL AS A SHORT WAVE LIFTS RAPIDLY NORTH-NORTHEAST ACROSS EASTERN IA. RAIN WILL CONTINUE TO BECOME LESS WIDESPREAD/MORE SHOWERY ACROSS THE LOCAL AREA BY DAWN AS A DRY SLOT...QUITE EVIDENT IN BOTH WATER VAPOR SATELLITE AND COMPOSITE RADAR LOOPS...PUNCHES ACROSS NORTHERN IL THIS MORNING. TRS PREVIOUS DISCUSSION...UPDATED 06Z... LARGE NE-SW BAND OF HEAVIER RAIN HAS BEEN SHIFTING EAST DURING THE EVENING AND AS OF LATE EVENING WAS EAST HAD PROGRESSED TO THE EAST OF ORD AND MDW. A BROAD BAND OF MAINLY LIGHT RAIN EXTENDED WESTWARD FROM THE HEAVIER RAIN BACK TO SOUTH CENTRAL WI...WEST CENTRAL IL AND SOUTH CENTRAL MO AS ADDITIONAL SHORT WAVES LIFT NORTHEAST AHEAD OF THE MAIN UPPER TROUGH WITH AN AXIS ALONG A SOUTHWEST ONTARIO TO NORTHERN TX LINE. THIS TROUGH AXIS IS PROGGED TO REACH SOUTHWEST WI...NORTHEAST MO AND WESTERN AR BY 18Z AS IS SHOWN CONTINUING EAST AND ACROSS THE LOCAL AREA DURING THE LATE AFTERNOON AND EARLY EVENING. EXPECTED PRECIPITATION TO PERSIST OVERNIGHT AND ALL THE WAY INTO EARLY EVENING. THE RAIN WILL MIX/SWITCH TO LIGHT SNOW AROUND MIDDAY AS A SOMEWHAT ILL DEFINED SURFACE LOW CURRENTLY OVER NORTHEAST IL/FAR SOUTHERN LAKE MI/NORTHWEST IN PROGRESSES NORTHEASTWARD THROUGH THE GREAT LAKES AND INTO ONTARIO BY 18Z... SPREADING COLD AIR ACROSS THE AREA AS THE TRAILING COLD FRONT PUSHES FURTHER EASTWARD. BETWEEN AN INCREASING PRESSURE GRADIENT SPREADING WEST TO EAST MIDDAY THROUGH EARLY EVENING NORTH-NORTHWEST TO NORTHWEST WINDS WILL INCREASE...AND STRENGTHENING OF THE COLD AIR ADVECTION DURING THIS TIME SUSTAINED WINDS OF 15-20KT AND GUSTS 25-30KT ARE EXPECTED MIDDAY AND WELL INTO TONIGHT. CEILINGS WILL STAY BELOW 010 INTO EARLY AFTERNOON THEN RISE A BIT TO THE 015-020 RANGE AS DEW POINT DEPRESSIONS INCREASE TO A FEW DEGREES IN THE COLD AIR. CEILINGS ARE FORECAST TO RISE TO AT OR ABOVE 020 IN THE EARLY TO MID EVENING AS THIS IS WHEN THE LIGHT SNOW IS EXPECTED TO END AND LOW LEVEL DEW POINT DEPRESSIONS INCREASE. TRS //ORD AND MDW CONFIDENCE...UPDATED 09Z... * MEDIUM CONFIDENCE IN TIMING OF SHITHC OVER FROM RAIN TO SNOW. * MEDIUM CONFIDENCE IN WIND TRENDS. * MEDIUM CONFIDENCE IN CEILING AND VISIBILITY TRENDS. TRS //OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z... THURSDAY...CHANCE OF FLURRIES IN THE AFTERNOON/EVENING. MVFR CIGS POSSIBLE. WEST WINDS GUSTING TO 25-30KT. FRIDAY...VFR EARLY. CHANCE OF SNOW WITH MVFR CIGS/VIS OVERNIGHT. SATURDAY...CHANCE OF SNOW WITH MVFR CIGS/VIS EARLY...THE VFR OVERNIGHT. SUNDAY...VFR. WX NIL. MONDAY...SLIGHT CHANCE RAIN/SNOW. MVFR CIGS/VIS POSSIBLE. KREIN && .MARINE... 1248 PM CST SEVERAL WAVES OF LOW PRESSURE WILL RIDE UP A SLOW MOVING COLD FRONT TONIGHT THROUGH WEDNESDAY AFTERNOON...AS THE FRONT TRAVERSES LAKE MICHIGAN. STRONG SOUTH TO SOUTHWEST WINDS AHEAD OF THE FRONT HAVE PROMPTED A SMALL CRAFT ADVISORY FOR THE IL AND IN NEARSHORE. WINDS WILL SUBSIDE AS THE FRONT APPROACHES THE ILLINOIS WATERS LATE THIS AFTERNOON...AND THE INDIANA WATERS THIS EVENING. AREAS OF DENSE FOG ARE POSSIBLE INTO THIS EVENING...MAINLY OVER THE SOUTH HALF OF THE LAKE...AS UNSEASONABLY MILD AND HUMID AIR MOVES OVER THE CHILLY WATER. BEHIND THE COLD FRONT...NORTHWEST WINDS WILL RAMP UP AS THE FINAL WAVE OF LOW PRESSURE MOVES INTO EASTERN CANADA AND INTENSIFIES...WHILE STRONG HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS. GALE FORCE WINDS WILL DEVELOP BY MID MORNING WEDNESDAY AND SLOWLY DIMINISH BELOW GALE FORCE THURSDAY MORNING. THE GALE WATCH WILL BE UPGRADED TO A GALE WARNING WITH THE 300 PM GLFLM ISSUANCE. STRONG WEST TO NORTHWEST WINDS WILL CONTINUE THROUGH FRIDAY BEFORE DIMINISHING THIS WEEKEND AS THE HIGH PRESSURE SETTLES OVER THE SOUTHEAST. FREEZING SPRAY IS LIKELY WEDNESDAY NIGHT AND THURSDAY DUE TO THE COMBINATION OF STRONG WINDS...LARGE WAVES...AND ARCTIC AIR OVER THE LAKE. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023- ILZ032-ILZ033-ILZ039 UNTIL 4 AM WEDNESDAY. WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ008...9 AM WEDNESDAY TO 4 PM WEDNESDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 4 AM WEDNESDAY. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM WEDNESDAY TO 9 AM THURSDAY. SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 4 AM FRIDAY. GALE WARNING...LMZ743-LMZ744-LMZ745...4 PM WEDNESDAY TO 4 AM THURSDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
111 AM CST WED JAN 30 2013 .MESOSCALE DISCUSSION... 240 PM CST THE THREAT FOR HEAVY RAIN DEVELOPING AND POSSIBLY A COUPLE SEVERE STORMS CONTINUES. THE LATEST HAND ANALYSIS PLACES THE COLD FRONT JUST PAST THE MISSISSIPPI RIVER IN NORTHWEST IL WITH A SUBTLE PRE-FRONTAL TROUGH FROM JUST EAST OF ROCKFORD SOUTH TOWARD PEORIA. THIS PRE- FRONTAL TROUGH DOES HAVE AN INSTABILITY PLUME AIDED BY LOW TO MID 60S TEMPERATURES...AND LOW-LEVEL CAPE IS ANALYZED NEAR 100 J/KG WITH AROUND 300-500 J/KG OF SURFACE-BASED CAPE. THIS INSTABILITY THOUGH IS NOT LINING UP WITH ANY GREAT STORM ACTIVITY. SATELLITE AND RADAR TRENDS SHOW THAT A LARGE SWATH OF RAIN HAS EXPANDED FROM MO NORTHEAST THROUGH WESTERN IL AND SOUTHERN WI...STABILIZING MUCH OF THAT AREA. AT THE FRONT EDGE OF THIS...NEAR THE PRE-FRONTAL TROUGH...MORE CONVECTIVE-LIKE SHOWERS ARE PRESENT. THAT CONVECTION ON THE ILX RADAR HAS STRUGGLED TO BECOME WELL-DEFINED AND HAS MORE OF A QUASI-LINEAR MUSHY LOOK RIGHT NOW. LIGHTNING HAS BEEN SOMEWHAT SPORADIC AND REALLY HAS ONLY BEEN SEEN IN THE CLUSTER THAT IS NEARING CHICAGO...POSSIBLY ASSOCIATED WITH A WARM AIR ADVECTION FLANK AHEAD OF THE SYSTEM. OVERALL THE TREND HAS BEEN SLIGHTLY DOWN WITH NO LOCAL STORMS APPROACHING SEVERE LIMITS...AND A FEW 30-37 KT GUSTS OBSERVED. AT THIS TIME...IT REMAINS QUITE MARGINAL FOR SEVERE WEATHER AND MAY CONTINUE TO THROUGH MUCH OF THE AFTERNOON AS NO IMMEDIATE STRONG IMPULSES UPSTREAM ARE EVIDENT. TOWARD SUNSET AND INTO THIS EVENING...AREAS ALONG AND EAST OF I-55 WILL REMAIN FAVORED FOR STORM ACTIVITY ON THE NOSE OF AN INCREASING LOW LEVEL JET AND JUST MORE IMPROVED OVERALL FORCING. EXPLICIT CONVECTIVE MODELS AGREE THIS AREA WILL BE UNDER SOME STRONGER ACTIVITY THIS EVENING...BUT WHETHER THAT IS TO THE LIMITS TO FLIRT WITH SEVERE IS LOW CONFIDENCE. THE FORECAST DCAPE DOES INCREASE TO AROUND 400-500 J/KG ON THE NAM AND THE LOW-LEVEL SHEAR/HELICITY REMAINS HIGH IN THE STRONG ATMOSPHERIC WINDS. THIS MAY END UP BEING OUR BEST...ALBEIT NARROW WINDOW FOR SEVERE WEATHER. HEAVY RAIN REMAINS THE PRIMARY POTENTIAL HAZARD. WHILE IT IS A QUASI- LINEAR MUSHY LOOK RIGHT NOW...RAINFALL RATES ARE LIKELY VERY EFFICIENT IN ANY ACTIVITY AND WILL CONTINUE AS SUCH LATE THIS AFTERNOON INTO TONIGHT. A PERSISTENT FOCUS IS SEEN IN THE RAP AND NAM FORECASTS AS DEEP LAYER MOISTURE CONVERGENCE FURTHER INCREASES TONIGHT AS THE UPPER TROUGH INCHES EASTWARD. WIDESPREAD RAINFALL AMOUNTS OF ONE TO TWO AND A HALF INCHES LOOK LIKELY...WITH POTENTIALLY THE HIGHER END AMOUNTS BEING WIDESPREAD. WITH MUCH OF THIS GOING TOWARD RUNOFF...AT LEAST LOCALIZED PONDING TO POSSIBLE FLOODING WILL BE LIKELY. MTF && .DISCUSSION... 318 PM CST SHORT TERM...REST OF TODAY THROUGH WEDNESDAY NIGHT... FOR HEADLINES...KEPT FLOOD WATCH AS IS AND NO WINTER HEADLINES ARE EXPECTED AT THIS TIME. A DEEP TROUGH LIES ACROSS THE WESTERN US WITH ITS AXIS OVER THE GREAT PLAINS...WHILE A SURFACE LOW IS OVER ONTARIO. THE SURFACE LOWS COLD FRONT EXTENDS FROM THE LOW THROUGH CENTRAL WI TO ALONG THE MISSISSIPPI RIVER...AND IT IS SLOWLY MAKING ITS WAY INTO WESTERN IL. THE TEMPERATURE GRADIENT ACROSS THE FRONT IS RATHER IMPRESSIVE WITH 60 DEGREES IN PERU IL AND 38 DEGREES IN OTTUMWA IA...WITH JUST 176 MILES BETWEEN THE TWO CITIES. SHOWERS AND THUNDERSTORMS HAVE SPREAD INTO NORTHERN IL AHEAD OF THE COLD FRONT AND WILL CONTINUE TO SPREAD ACROSS THE CWA THIS AFTERNOON/EARLY EVENING. INDIVIDUAL CELLS HAVE BEEN CLOCKED AT 50-60 KT MOVING FROM THE SOUTHWEST TO THE NORTHEAST. SEVERE STORMS ARE STILL POSSIBLE THIS AFTERNOON...FOR MORE INFORMATION ON THE SEVERE WEATHER OUTLOOK AND RELATED PARAMETERS PLEASE SEE THE MESOSCALE DISCUSSION ABOVE. PWAT VALUES WILL BE IN EXCESS OF 1-1.5 INCHES THIS AFTERNOON/EVENING WITH DEW POINTS CURRENTLY IN THE UPPER 50S TO LOW 60S FALLING OVERNIGHT. FLOW THROUGHOUT THE ATMOSPHERIC COLUMN IS ROUGHLY PARALLEL TO THE FRONT WHICH WILL INHIBIT THE FRONT FROM RAPIDLY PROGRESSING THROUGH THE CWA. TRAINING WILL ALSO BECOME AN ISSUE ALONG THE FRONT ALLOWING FOR IMPRESSIVE RAIN TOTALS. THE UPPER LEVEL JET STRETCHES FROM TEXAS THROUGH MINNESOTA BEFORE CURVING TOWARD QUEBEC. THE RIGHT JET ENTRANCE REGION LIES OVER SOUTHWEST WI/NORTHWEST IL ALMOST COLLOCATED WITH THE FRONT WHICH WILL CONTINUE TO SUPPORT THUNDERSTORM AND SHOWER FORMATION. BASED ON WHAT HAS PASSED OVER THE OFFICE THIS AFTERNOON...SOME OF THESE SHOWERS/STORMS WILL PRODUCE BRIEF INTENSE DOWNPOURS. THE JET AND FRONT CONTINUE ACROSS THE CWA TONIGHT WITH THE SOUTHERN JET STREAKS LEFT EXIT REGION POSSIBLY COUPLING WITH THE FRONT. AS SUCH EXPECTING PERIODS OF HEAVY RAIN TO CONTINUE OVERNIGHT. WHEN ALL IS SAID AND DONE...THINKING 1.5-2.5 INCHES OF RAIN ARE POSSIBLE ACROSS THE AREA. LOCALLY HIGHER AMOUNTS ARE CERTAINLY POSSIBLE. QUICKLY CHECKING THE OFFICES SOIL TEMPS...2 AND 4 INCHES BELOW THE SURFACE ARE ABOVE FREEZING AT 35 DEGREES WHILE 8 INCHES IS STILL FROZEN AT 27 DEGREES. AS SUCH EXPECTING PONDING OF WATER IN THE TYPICAL LOW LYING SPOTS...SINCE THE SOIL WILL NOT BE ABLE TO TAKE IN AS MUCH WATER AS USUAL. THEREFORE MADE NO ADJUSTMENTS TO THE FLOOD WATCH. TEMPS WILL BEGIN TO FALL OVERNIGHT WITH LOWS IN THE LOW 30S NEAR RFD TO ARND 50 NEAR RENSSELAER. WEDNESDAY... TEMPS WILL CONTINUE TO FALL WEDNESDAY MORNING WITH PRECIP TRANSITIONING TO SNOW AS A SWATH OF MOISTURE ASSOCIATED WITH THE 700 MB LOW SURGES NORTH. SOUNDINGS INDICATE A BRIEF PERIOD OF SLEET IS POSSIBLE DURING THE TRANSITION BUT NOT EXPECTING ANY SIGNIFICANT SLEET ACCUMULATION. EXPECTING AREAS AROUND RFD TO CHANGE OVER TO SNOW BEFORE 8AM...CHICAGO AROUND 3PM...AND NW INDIANA 4-6PM. FOR SNOW TOTALS...EXPECTING THE HIGHEST TOTALS IN FAR NW IL IN WINNEBAGO AND OGLE COUNTIES. THE NAM IS MUCH MORE EXCITED THAN THE GFS ABOUT THE SNOW POTENTIAL BUT BOTH MODELS SHOW THE SAME SET UP THAT IS FAVORABLE FOR MESOSCALE SNOW BANDS. 850-700 MB FRONTOGENESIS MOVES OVER NW IL/E IA EARLY WEDNESDAY MORNING WITH EPV VALUES BELOW 0 JUST ABOVE IT...INDICATING LOCALIZED INTENSE FORCING AND SYMMETRIC INSTABILITY. HOWEVER EXPECTING TEMPS TO BE ABOVE FREEZING AT THIS POINT. THE FRONTOGENESIS AND INSTABILITY SHIFT EASTWARD THROUGH THE MORNING AND THEN WEAKEN AFTER NOON. THE LEFT JET EXIT REGION OF THE UPPER LEVEL JET WILL ALSO BE OVER NORTHERN IL THROUGH WEDNESDAY AFTERNOON SO SYNOPTIC-SCALE LIFT SHOULD NOT BE AN ISSUE. WHILE MESOSCALE BANDS OF RAIN OR SNOW ARE VERY LIKELY TOMORROW...THESE FEATURES ARE HARD TO PINPOINT EVEN THIS FAR OUT. THEREFORE WENT WITH 3-5 INCHES OF SNOW OVER WINNEBAGO AND OGLE COUNTIES TOMORROW...BUT THIS NUMBER COULD EASILY BE HIGHER IF A BAND OF SNOW SETS UP. THE BIG QUESTIONS ARE WILL THE BEST FORCING ALIGN WITH SNOW OR RAIN...HOW LONG WILL THE FORCING LAST...AND WHERE WILL THE MESOSCALE BAND SET UP. AS MENTIONED BEFORE...THE FRONTOGENESIS WEAKENS AND STABILITY INCREASES IN THE AFTERNOON AS THE SNOW SPREADS ACROSS THE REST OF THE CWA. SO INTENSE MESOSCALE BANDS ARE NOT AS LIKELY...BUT FORCING FROM THE UPPER LEVEL JET STILL LOOKS FAVORABLE FOR A LITTLE SNOW. AS SUCH EXPECTING 1 TO 3 INCHES OF SNOW ACROSS BOONE AND MCHENRY COUNTIES...AND THEN AN INCH OR LESS EVERYWHERE ELSE. SNOW ENDS FROM WEST TO EAST...WITH NO SNOW EXPECTED AFTER MIDNIGHT ON WEDNESDAY. TEMPS CONTINUE TO TUMBLE TO THE TEENS OR SINGLE DIGITS WEDNESDAY NIGHT. WINDS 20-25 MPH WITH GUSTS UP TO 30 MPH SLOWLY WEAKEN OVERNIGHT...BUT EXPECTING WIND CHILLS TO BE BTWN 1 AND -10. JEE EXTENDED PERIOD...THURSDAY THROUGH TUESDAY... MAIN FORECAST CONCERN IN EXTENDED PERIOD DEALS WITH REINFORCEMENT OF ARCTIC COLD THURSDAY NIGHT/FRIDAY...AND THE POTENTIAL FOR LIGHT SNOW FRIDAY NIGHT/SATURDAY WITH A COUPLE CLIPPER-TYPE SYSTEMS ON THE BACK SIDE OF THE RETREATING LOW LEVEL COLD AIR. MEDIUM RANGE GUIDANCE APPEARS TO BE IN GOOD AGREEMENT AT THE START OF THE PERIOD THURSDAY MORNING...WITH DEEP SURFACE LOW LIFTING NORTHEAST ACROSS EASTERN QUEBEC AND DEEP UPPER LEVEL TROUGH ACROSS MUCH OF EASTERN NORTH AMERICA. ALL OF THE GLOBAL MODELS DEPICT ANOTHER STRONG SHORT WAVE DIGGING SOUTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES REGION THROUGH THE DAY... ACCOMPANIED BY A STRONG PUSH OF COLD ARCTIC AIR WITH 850 MB TEMPS OF -22 TO -24 C MOVING INTO THE CWA BY THURSDAY EVENING. MODEL SOUNDINGS AND TIME/HEIGHT SERIES INDICATE DRY MID/UPPER LEVELS AHEAD OF THIS DIGGING SHORT WAVE...WITH MODEL GENERATED QPF LIMITED TO THE MID/LOWER MISSOURI RIVER VALLEY INTO THE LOWER OHIO VALLEY THURSDAY AFTERNOON AND EVENING...THE COMBINATION OF DIGGING VORT...COLD ADVECTION WITH VERY COLD ARCTIC AIR...AND RELATIVELY MOIST LOW LEVELS ALL POINT TO THE POTENTIAL FOR AT LEAST SOME FLURRIES ACROSS THE FORECAST AREA THURSDAY AFTERNOON/EVENING. TEMPS...WHICH SHOULD ONLY TOP OUT IN THE MID TEENS NORTH AND LOWER 20S SOUTH AFTER WEDNESDAYS COLD FRONT...SHOULD EASILY FALL TO AROUND/BELOW ZERO ACROSS NORTH CENTRAL IL BY SUNRISE FRIDAY AND TO PERHAPS THE LOW POSITIVE SINGLE DIGITS ACROSS THE SOUTH WITH STRONG LOW LEVEL COLD ADVECTION THURSDAY NIGHT. HAVE TRENDED COLDER TOWARD THE 00Z GEFS MOS...AND A FEW DEGREES BELOW THAT AROUND ROCKFORD. THIS MAY NOT BE COLD ENOUGH ESPECIALLY IF SIGNIFICANT SNOW PACK IS IN PLACE AFTER WEDNESDAY. WINDS SHOULD REMAIN BLUSTERY ESPECIALLY IN THE EVENING WITH THE ENHANCED GRADIENT TO THE EAST OF THE CANADIAN HIGH BUILDING SOUTHEAST THROUGH THE PLAINS...SUPPORTING WIND CHILLS -10 TO -20 F OVERNIGHT. THE MID-LEVEL SHORT WAVE TROUGH AXIS IS PROGGED TO MOVE OFF TO THE SOUTHEAST OF THE FORECAST AREA EARLY FRIDAY MORNING...WITH FAIRLY STRONG HEIGHT RISES DEVELOPING IN ITS WAKE. COLD SURFACE HIGH PRESSURE CENTER WILL CONTINUE TO PUSH SOUTHEAST THROUGH THE LOWER OHIO VALLEY INTO TENNESSEE BY EVENING. CORE OF THE COLDEST AIR WILL SHIFT OFF TO THE EAST/SOUTHEAST BY AFTERNOON...THOUGH COLD MORNING START AND SHALLOW MIXED LAYER BENEATH SUBSIDENCE INVERSION WILL ALLOW ONLY MARGINAL MODERATION OF TEMPS AT THE SURFACE. HAVE ALSO TRENDED COLDER WITH MAXES FRIDAY TOWARD COLDER GFS/GEFS MOS NUMBERS. NORTHERN EXTENT OF SURFACE RIDGE AXIS MOVES ACROSS THE CWA FRIDAY EVENING...WITH WARM ADVECTION ALREADY DEVELOPING ON THE WESTERN PERIPHERY OF THE RETREATING LOW LEVEL COLD AIR DOME. WITH NORTHWEST FLOW ALOFT ON THE BACK SIDE OF THE DEPARTING LONG-WAVE UPPER TROUGH THIS SETS THE STAGE FOR A COUPLE OF MODEST SHORT WAVES TO BRING A COUPLE POTENTIAL PERIODS OF LIGHT SNOW TO THE REGION FRIDAY NIGHT AND SATURDAY. ECMWF/GFS 12Z RUNS REMAIN IN FAIRLY GOOD AGREEMENT IN DEVELOPING LIGHT QPF ACROSS THE AREA WITH A WEAK SURFACE LOW MOVING ACROSS NORTHERN ILLINOIS SATURDAY. UPPER JET CORE THEN SHIFTS SLOWLY EAST/NORTHEAST ACROSS THE NORTHERN/CENTRAL GREAT LAKES SATURDAY NIGHT...AS HIGH PRESSURE RIDGE MOVES ACROSS THE REGION THROUGH SUNDAY. WITH COLD CORE OF UPPER TROUGH OFF TO THE EAST...TEMPS MODERATE BACK TO MORE SEASONABLE LEVELS SATURDAY (MID-UPPER 20S) AND PERHAPS A BIT ABOVE (30S) SUNDAY AS WINDS SHIFT SOUTH IN THE AFTERNOON WEST OF THE RIDGE AXIS. MODERATION LOOKS TO CONTINUE MONDAY AS ECMWF/GFS REMAIN IN GOOD AGREEMENT IN TAKING AN AREA OF SURFACE LOW PRESSURE NORTH OF THE CWA ACROSS MN/WI. DRY HIGH PRESSURE BLOCKS MOISTURE RETURN FROM THE SOUTH FOR THE MOST PART... WITH NEXT CHANCE OF ORGANIZED PRECIP OCCURRING WITH THE COLD FRONT ASSOCIATED WITH THIS LOW MONDAY/MONDAY NIGHT...AND MAINLY ACROSS THE SOUTHEASTERN CWA. GEM MEANWHILE DURING THIS PERIOD BECOMES A COLD OUTLIER...WITH CONSISTENT ECMWF/GFS SOLUTIONS FAVORED AT THIS DISTANCE. THIS WOULD INDICATE COOLER/SEASONAL TEMPS RETURN TUESDAY. RATZER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * CONTINUED LIGHT RAIN...OCCASIONALLY MODERATE...PERSISTING INTO LATE MORNING...THEN MIXING/SWITCHING TO LIGHT SNOW DURING LATE MORNING TO EARLY AFTERNOON BEFORE ENDING FIRST PART OF EVENING.. * PREVAILING IFR INTO LATE AFTERNOON...THEN MVFR THROUGH THE EVENING. * WINDS BECOME NORTH TO NORTHWEST AND INCREASE DURING THE MORNING...WITH GUSTS GENERALLY 25-30KT FROM MIDDAY AND THROUGH THE EVENING. TRS //DISCUSSION...UPDATED 06Z... LARGE NE-SW BAND OF HEAVIER RAIN HAS BEEN SHIFTING EAST DURING THE EVENING AND AS OF LATE EVENING WAS EAST HAD PROGRESSED TO THE EAST OF ORD AND MDW. A BROAD BAND OF MAINLY LIGHT RAIN EXTENDED WESTWARD FROM THE HEAVIER RAIN BACK TO SOUTH CENTRAL WI...WEST CENTRAL IL AND SOUTH CENTRAL MO AS ADDITIONAL SHORT WAVES LIFT NORTHEAST AHEAD OF THE MAIN UPPER TROUGH WITH AN AXIS ALONG A SOUTHWEST ONTARIO TO NORTHERN TX LINE. THIS TROUGH AXIS IS PROGGED TO REACH SOUTHWEST WI...NORTHEAST MO AND WESTERN AR BY 18Z AS IS SHOWN CONTINUING EAST AND ACROSS THE LOCAL AREA DURING THE LATE AFTERNOON AND EARLY EVENING. EXPECTED PRECIPITATION TO PERSIST OVERNIGHT AND ALL THE WAY INTO EARLY EVENING. THE RAIN WILL MIX/SWITCH TO LIGHT SNOW AROUND MIDDAY AS A SOMEWHAT ILL DEFINED SURFACE LOW CURRENTLY OVER NORTHEAST IL/FAR SOUTHERN LAKE MI/NORTHWEST IN PROGRESSES NORTHEASTWARD THROUGH THE GREAT LAKES AND INTO ONTARIO BY 18Z... SPREADING COLD AIR ACROSS THE AREA AS THE TRAILING COLD FRONT PUSHES FURTHER EASTWARD. BETWEEN AN INCREASING PRESSURE GRADIENT SPREADING WEST TO EAST MIDDAY THROUGH EARLY EVENING NORTH-NORTHWEST TO NORTHWEST WINDS WILL INCREASE...AND STRENGTHENING OF THE COLD AIR ADVECTION DURING THIS TIME SUSTAINED WINDS OF 15-20KT AND GUSTS 25-30KT ARE EXPECTED MIDDAY AND WELL INTO TONIGHT. CEILINGS WILL STAY BELOW 010 INTO EARLY AFTERNOON THEN RISE A BIT TO THE 015-020 RANGE AS DEW POINT DEPRESSIONS INCREASE TO A FEW DEGREES IN THE COLD AIR. CEILINGS ARE FORECAST TO RISE TO AT OR ABOVE 020 IN THE EARLY TO MID EVENING AS THIS IS WHEN THE LIGHT SNOW IS EXPECTED TO END AND LOW LEVEL DEW POINT DEPRESSIONS INCREASE. TRS //ORD AND MDW CONFIDENCE...UPDATED 06Z... * HIGH CONFIDENCE IN PRECIPITATION TRENDS. * MEDIUM CONFIDENCE IN WIND TRENDS. * MEDIUM CONFIDENCE IN CEILING AND VISIBILITY TRENDS. TRS //OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z... THURSDAY...CHANCE OF FLURRIES IN THE AFTERNOON/EVENING. MVFR CIGS POSSIBLE. WEST WINDS GUSTING TO 25-30KT. FRIDAY...VFR EARLY. CHANCE OF SNOW WITH MVFR CIGS/VIS OVERNIGHT. SATURDAY...CHANCE OF SNOW WITH MVFR CIGS/VIS EARLY...THE VFR OVERNIGHT. SUNDAY...VFR. WX NIL. MONDAY...SLIGHT CHANCE RAIN/SNOW. MVFR CIGS/VIS POSSIBLE. KREIN && .MARINE... 1248 PM CST SEVERAL WAVES OF LOW PRESSURE WILL RIDE UP A SLOW MOVING COLD FRONT TONIGHT THROUGH WEDNESDAY AFTERNOON...AS THE FRONT TRAVERSES LAKE MICHIGAN. STRONG SOUTH TO SOUTHWEST WINDS AHEAD OF THE FRONT HAVE PROMPTED A SMALL CRAFT ADVISORY FOR THE IL AND IN NEARSHORE. WINDS WILL SUBSIDE AS THE FRONT APPROACHES THE ILLINOIS WATERS LATE THIS AFTERNOON...AND THE INDIANA WATERS THIS EVENING. AREAS OF DENSE FOG ARE POSSIBLE INTO THIS EVENING...MAINLY OVER THE SOUTH HALF OF THE LAKE...AS UNSEASONABLY MILD AND HUMID AIR MOVES OVER THE CHILLY WATER. BEHIND THE COLD FRONT...NORTHWEST WINDS WILL RAMP UP AS THE FINAL WAVE OF LOW PRESSURE MOVES INTO EASTERN CANADA AND INTENSIFIES...WHILE STRONG HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS. GALE FORCE WINDS WILL DEVELOP BY MID MORNING WEDNESDAY AND SLOWLY DIMINISH BELOW GALE FORCE THURSDAY MORNING. THE GALE WATCH WILL BE UPGRADED TO A GALE WARNING WITH THE 300 PM GLFLM ISSUANCE. STRONG WEST TO NORTHWEST WINDS WILL CONTINUE THROUGH FRIDAY BEFORE DIMINISHING THIS WEEKEND AS THE HIGH PRESSURE SETTLES OVER THE SOUTHEAST. FREEZING SPRAY IS LIKELY WEDNESDAY NIGHT AND THURSDAY DUE TO THE COMBINATION OF STRONG WINDS...LARGE WAVES...AND ARCTIC AIR OVER THE LAKE. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023- ILZ032-ILZ033-ILZ039 UNTIL 4 AM WEDNESDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 4 AM WEDNESDAY. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM WEDNESDAY TO 6 AM THURSDAY. SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742...6 AM WEDNESDAY TO 10 AM THURSDAY. GALE WARNING...LMZ743-LMZ744-LMZ745...4 PM WEDNESDAY TO 4 AM THURSDAY. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1135 PM CST TUE JAN 29 2013 .DISCUSSION... ISSUED 905 PM CST TUE JAN 29 2013 INITIAL WIND SHIFT HAS PUSHED THROUGH ABOUT 3/4 OF THE CWA... CURRENTLY EXTENDING FROM ABOUT EFFINGHAM TO DANVILLE. TEMPERATURES STILL IN THE 60-65 RANGE AHEAD OF THIS AREA...WITH SOME GRADIENT WIND GUSTS OF 35-40 MPH. THE MAIN COLD FRONT WAS LOCATED JUST EAST OF THE IOWA BORDER...WHERE TEMPERATURES FALL INTO THE 30S. HAVE HAD SOME WAVES OF LOW PRESSURE RIDING ALONG THE FRONT...WHICH HAS SLOWED DOWN ITS PASSAGE SOMEWHAT...BUT LATEST MODEL GUIDANCE STILL INDICATES IT SHOULD START MOVING THROUGH THE WESTERN CWA LATE TONIGHT. MAIN CONCERN REMAINS WITH THE RAIN TONIGHT AND THE FLOOD WATCH. EVENING UPPER AIR SOUNDING FROM LINCOLN HAD PRECIPITABLE WATER VALUES OF 1.43 INCHES...WHICH LOCAL RESEARCH INDICATES IS A RECORD FOR JANUARY IN THIS AREA. SO FAR...HAVE SEEN LITTLE OR NO RAIN IN THE FAR SOUTHEAST CWA...BUT THAT SHOULD BE INCREASING SHORTLY AS A NARROW CONVECTIVE LINE FROM SALEM SOUTHWEST INTO MISSOURI MOVES QUICKLY EASTWARD. RAP MODEL SHOWS THE SAME HIGH PWAT VALUES AFFECTING SOUTHEAST ILLINOIS OVER THE NEXT SEVERAL HOURS...SO SOME HEAVY RAIN THERE IS STILL LIKELY. THE WESTERN HALF OF THE CWA HAS SEEN AMOUNTS OVER AN INCH COMMON WEST OF A BLOOMINGTON TO JACKSONVILLE LINE...WITH SOME 1.5 TO 2 INCH TOTALS TOWARD THE ILLINOIS RIVER VALLEY. HAVE KEPT THE FLOOD WATCH IN PLACE FOR NOW OVER THE ENTIRE AREA...BUT HAVE SOME CONCERNS ABOUT THE NORTHWEST CWA...AS REGIONAL RADAR MOSAICS SHOW THE HEAVIEST AXIS OF RAIN FURTHER TO THE EAST. WILL WATCH THIS FOR A COUPLE MORE HOURS BEFORE DECIDING WHETHER OR NOT TO TRIM DOWN THE WATCH AREA. UPDATED ZONES/GRIDS HAVE BEEN SENT. GEELHART && .AVIATION... ISSUED 1127 PM CST TUE JAN 29 2013 PRIMARY FRONTAL BOUNDARY ROUGHLY ALONG A KUIN-KSQI LINE AND WILL PUSH SLOWLY EASTWARD THE NEXT SEVERAL HOURS. A WAVE OF LOW PRESSURE RIDING ALONG THE FRONT WILL SLOW ITS PROGRESSION THROUGH ABOUT 15Z...THEN AFTER THAT...WINDS WILL MORE CONSISTENTLY SWING AROUND TO THE NORTHWEST. HIGHEST WINDS EXPECTED DURING THE AFTERNOON AND EVENING...WITH SOME GUSTS EXCEEDING 30 KNOTS. LARGE RAIN SHIELD WILL BECOME MORE SCATTERED IN NATURE OVER THE NEXT FEW HOURS...HOWEVER A LARGER AREA OF PRECIPITATION WILL REDEVELOP OVER MISSOURI AND IOWA BEFORE MOVING EASTWARD. FORECAST SOUNDINGS ARE SLOWING THE TRANSITION TO SNOW A BIT...BUT SHOULD SWITCH AROUND 14Z NEAR KPIA AND TOWARD 17Z AROUND KDEC. CEILINGS HAVE BEEN DROPPING BACK INTO IFR RANGE OVER WEST CENTRAL ILLINOIS AND THIS SHOULD BECOME MORE WIDESPREAD OVER THE NEXT FEW HOURS. GEELHART && .PREV DISCUSSION... ISSUED 320 PM CST TUE JAN 29 2013 MAIN CONCERN THIS FORECAST PACKAGE CONTINUES TO INVOLVE THE POTENTIAL HEAVY RAIN/FLOOD WATCH EVENT FOR TONIGHT...WHEN RAIN WILL CHANGE OVER TO SNOW...AND FALLING TEMPS IN THE SHORT TERM. ALL MODELS IN GOOD AGREEMENT WITH OVERALL UPPER LEVEL PATTERN THROUGH THE SHORT TERM...AND WITH THE SFC FEATURES AND MOVEMENTS THROUGH FRIDAY. EXTENDED MODELS HAVE TRENDED INTO BETTER AGREEMENT IN THE EXTENDED WITH SFC FEATURES AS WELL. THEREFORE CONFIDENCE IS ABOVE AVERAGE FOR THIS FORECAST PACKAGE. SHORT TERM...TONIGHT THROUGH FRIDAY A SFC LOW IN CENTRAL OKLAHOMA IS FORECAST TO CONTINUE TO MOVE NORTHEAST ALONG A FRONTAL SYSTEM STRETCHING FROM WI...THROUGH NORTHWESTERN IL...THROUGH MO AND INTO OK. THIS LOW WILL MOVE ACROSS CENTRAL ILLINOIS THIS EVENING AND INTO SOUTHERN MICH JUST AFTER MIDNIGHT. THE UPPER LEVEL TROUGH ASSOCIATED WITH THIS SFC SYSTEM WILL REMAIN BACK IN THE CENTRAL US AND NOT MOVE INTO AND THROUGH THE CWA UNTIL TOMORROW EVENING. THE TROUGH MOVES THROUGH...BUT THEN BROADENS AS ANOTHER SMALLER AND LESS INTENSE SFC LOW MOVES OUT OF THE PLAINS AND THROUGH SOUTHERN IL THURSDAY. THIS WILL PUSH THROUGH QUICKLY AND THEN COLD HIGH PRSS MOVES BACK INTO THE AREA FOR THUR NIGHT AND FRIDAY. SHOWERS AND THUNDERSTORMS WITH HEAVY RAINFALL ARE FORECAST TO CONTINUE TO MOVE ACROSS THE CWA TONIGHT. STORMS WILL BE MOVING VERY QUICKLY TO THE NORTHEAST THIS EVENING AND COULD BE SEVERE AT TIMES WITH DAMAGING WINDS. TORNADO WATCHES ARE ONGOING TO THE SOUTHWEST OF THE AREA...AND OUR CWA MAY HAVE TO BE INCLUDED LATER THIS AFTERNOON AND INTO THIS EVENING IF THE STORMS SOUTHWEST OF THE AREA MAINTAIN THEIR STRENGTH AS THEY MOVE NORTHEAST. TOMORROW...THE PCPN WILL BEGIN TO CHANGE TO ALL SNOW AS MUCH COLDER AIR ADVECTS INTO THE AREA. MODELS ARE FORECASTING AN AREA OF DEFORMATION SNOW TO SETUP WEST OF THE TRACK OF THE SFC LOW TOMORROW WITH THE HIGHEST ACCUMULATING SNOW STAYING NORTHWEST OF THE IL RIVER. LOOKING FOR ABOUT AN INCH ALONG A RUSHVILLE TO BLOOMINGTON LINE WITH UP TO AROUND 1.5 INCHES AROUND GALESBURG. AMOUNTS OF A HALF AN INCH OR LESS WILL BE ALONG I-72. AS THIS SYSTEM PULLS EAST AND NORTHEAST...A SLIGHT CHANCE OF SNOW WILL CONTINUE ACROSS THE EXTREME NORTHEAST OF THE CWA WED NIGHT. WITH THE TROUGH BROADENING...A SFC LOW WILL MOVE OUT OF THE PLAINS AND THROUGH SOUTHERN IL THURSDAY. THIS WILL BRING A SLIGHT CHANCE OF MORE SNOW TO THE WHOLE CWA...MAINLY THUR AFTERNOON. BEYOND THIS...COLD ARCTIC HIGH PRSS WILL DROP INTO THE REGION WITH DRY AND VERY COLD WEATHER FOR THUR NIGHT AND FRIDAY. LOWS TONIGHT WILL BE CLOSE TO MIDNIGHT AND HIGHS TOMORROW WILL PROBABLY BE JUST AFTER MIDNIGHT TONIGHT. TEMPS WILL THEN GRADUALLY FALL TOMORROW THROUGH TOMORROW NIGHT. THEN COLDER AIR WILL ADVECT INTO THE REGION FOR THUR NIGHT AND FRIDAY...WITH TEMPS AROUND ZERO IN THE NORTHWEST TO IN THE LOWER TEENS IN THE SOUTHEAST...FOR THUR NIGHT. FRI TEMPS WILL BE WELL BELOW NORMAL FOR FRIDAY AS WELL...NOT REACHING ABOVE FREEZING ANYWHERE IN THE CWA. LONG TERM...FRIDAY NIGHT THROUGH TUESDAY MODELS HAVE ANOTHER SFC LOW DROPPING ACROSS NORTHERN IL FRIDAY NIGHT...SPREADING SOME LIGHT SNOW ACROSS THE NORTHEASTERN HALF OF THE CWA. THIS CLIPPER SYSTEM WILL BE QUICK SO ACCUMULATIONS WILL BE VERY LIGHT. BEYOND THIS...ANOTHER WEAK SYSTEM IS FORECAST TO MOVE ACROSS THE AREA WITH LIGHT PCPN MON AND MONDAY NIGHT. FOR NOW WILL KEEP ONLY SLIGHT CHC OF POPS IN THE FORECAST...WHICH WILL NOT BE MENTIONED IN THE WORDED FORECAST. OTHER THAN THESE TWO SYSTEMS...REMAINDER OF THE LONG TERM PERIODS WILL BE DRY. TEMPS WILL START COLD BUT THEN WARM QUICKLY FOR THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. WARMEST DAY LOOKS TO BE MONDAY WITH TEMPS 5+ DEGREES ABOVE NORMAL. AUTEN && .ILX WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH UNTIL 6 AM CST WEDNESDAY FOR ILZ028>031-037-038- 042>046-051>057-061>063-066>068-071>073. && $$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
305 AM EST TUE JAN 29 2013 .UPDATE... LONG TERM SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 337 PM EST TUE JAN 29 2013 NUMEROUS WEATHER HAZARDS WILL ACCOMPANY AN EXTREMELY POTENT SYSTEM IMPACTING THE REGION THROUGH TOMORROW. VERY UNSEASONABLY WARM AND MOIST CONDITIONS WILL BE IN PLACE THROUGH TONIGHT. AHEAD OF A STRONG COLD FRONT SWEEPING THROUGH THE REGION...THE POTENTIAL WILL EXIST FOR THUNDERSTORMS...HEAVY RAINFALL...FLOODING AND DAMAGING WINDS. POTENTIAL FOR STRONG WINDS WILL CONTINUE BEHIND THE FRONTAL BOUNDARY ON WEDNESDAY...AND FLOODING MAY LAST FOR SEVERAL DAYS OR MORE. && .NEAR TERM /REST OF TONIGHT/... ISSUED AT 942 PM EST TUE JAN 29 2013 UPDATE... LINE OF STRONG TO SEVERE THUNDERSTORMS IS WELL OUT AHEAD OF THE COLD FRONT AND CURRENTLY PUSHING EASTWARD THROUGH ILLINOIS AND WESTERN KENTUCKY. TEMPS ACROSS CENTRAL INDIANA HAVE BEEN SLOWLY RISING A FEW DEGREES OVER THE LAST FEW HOURS AS STRONG LOW LEVEL JET ADVECTS WARM AIR AHEAD OF IT. SO...LOSS OF DIURNAL HEATING HAS HAD LITTLE AFFECT ON ENVIRONMENT. INSTABILITY LOOKS MOST FAVORABLE FOR SEVERE STORMS ACROSS THE SOUTHERN PORTIONS OF FORECAST AREA PER LATEST LAPS ANALYSES. PREVIOUS DISCUSSION... FOCUS OF THE NEAR TERM REMAINS ON SEVERE WEATHER CHANCES AS WELL AS POSSIBLE HEAVY RAINFALL/FLOODING POSSIBILITIES TONIGHT. THE PERIOD BEGINS WITH GOOD SHORT TERM MODEL AGREEMENT AS TO THE LOCATION OF KEY FEATURES THAT MAY BRING POSSIBLE SEVERE TO PORTIONS OF THE FORECAST AREA TONIGHT. AT 00Z/WED...THE LOW PRESSURE CENTER IS PROGGED TO BE OVER CENTRAL MISSOURI...WITH ONGOING CONVECTION POSSIBLY ALREADY IN THE FORM OF A SQUALL LINE ALONG A STRONG COLD FRONT STRETCHED FROM NORTHWEST ILLINOIS...DOWN THROUGH CENTRAL MISSOURI...INTO EASTERN OKLAHOMA/WESTERN ARKANSAS. THERE DOES APPEAR TO BE SOME DIFFERENCES IN SPEED/TIMING OF THE FRONT INTO THE FORECAST AREA...WITH THE HRRR AND RAP INTO THE AREA A BIT QUICKER THE THE NAM AND GFS. PERSONAL EXPERIENCE HAS SHOWN THAT THESE COLD FRONT/SQUALL LINE FEATURES TEND TO COME IN A BIT QUICKER THAN SOMETIMES EXPECTED. THEREFORE...DECIDED TO TREND TOWARD THE HRRR/RUC SOLNS. AS WAS MENTIONED IN PREVIOUS DISCUSSIONS...DYNAMICS WILL NOT BE AN ISSUE WITH THIS SYSTEM AS THE FRONT APPROACHES. A LOW LEVEL JET AOA 80 KTS AT 850 MB IS EXPECTED TO DEVELOP OUT AHEAD OF THE FRONT THIS EVENING AND WILL TRANSLATE INTO OUR AREA TONIGHT. WITH 50 KT WINDS LOCATED APPROXIMATELY 1000-1500 FEET ABOVE THE SURFACE TONIGHT...DAMAGING WINDS MAY BECOME A REAL THREAT WITH ANY STORMS THAT ARE ABLE TO REMAIN ORGANIZED AS THEY PUSH INTO THE FORECAST AREA. ONE LIMITING FACTOR FOR CONVECTION REMAINING ORGANIZED INTO THE OVERNIGHT HOURS IS INSTABILITY. SFC-BASED CAPE LOOKS TO BE IN THE UNDER 200 J/KG RANGE...WHILE MUCAPE GIVES SLIGHTLY HIGHER VALUES OF 200-400 J/KG AS THE FRONT MOVES INTO THE AREA. WITH THE STRONG DYNAMICS AVAILABLE...WILL CONTINUE DAMAGING WINDS REFERENCE IN THE GRIDS. ALSO KEEP IN MIND THAT WITH AMPLE LOW LEVEL SHEAR...0-1 HELICITIES AOA 400-500 M2/S2...AN ISOLATED TORNADO CANNOT BE RULED OUT. THE BEST TIMING FOR SEVERE LOOKS TO START AT APPROXIMATELY 04-05Z ACROSS WESTERN PORTIONS OF THE FORECAST AREA...TO ABOUT 10-11Z OVER THE EAST. JUST ONE OTHER NOTE TO MENTION...THE HRRR ILLUSTRATES A LINE OF CONVECTION DEVELOPING OUT AHEAD OF THE MAIN SQUALL LINE. TO A LESSER EXTENT...THE RAP ALSO DEPICTS A SIMILAR SCENARIO. WHILE THIS FORECAST HAS TAKEN THIS INTO CONSIDERATION...IT COULD STILL ALLOW FOR AN EARLIER ONSET THAN FORECAST. HEAVY RAINFALL IS ALSO IN PLAY TONIGHT AS MOISTURE HAS CONTINUED TO STREAM NORTH INTO THE AREA. A PACIFIC TROPICAL PLUME OF MOISTURE HAS BEEN EVIDENT ALL DAY ON WATER VAPOR IMAGERY STREAMING NORTHWEST INTO LOWER MISSOURI/MID MISSISSIPPI/OHIO RIVER VALLEY STATES. COUPLE THAT WITH 60 DEGREE DEWPOINTS CURRENTLY ON THE SOUTHWESTERN DOORSTEP OF THE FORECAST AREA. PWATS TONIGHT AHEAD OF THE FRONT LOOK TO REACH UPWARDS OF 1.40-1.50 INCHES...YIELDING A PERCENT OF NORMAL OF AROUND 300 PERCENT. WOULD NOT BE SURPRISED TO SEE A WIDESPREAD 1 TO 1.5 INCH RAINFALL...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... ISSUED AT 337 PM EST TUE JAN 29 2013 SHORT TERM PERIOD SEES A DIFFERENT SET OF CHALLENGES. ONE OF THE INITIAL CHALLENGES WILL BE STRONG WINDS AFTER THE COLD FRONT SWEEPS THROUGH THE AREA AND A DRY SLOT APPROACHES THE FORECAST AREA DURING THE AFTERNOON HOURS. SUSTAINED WINDS AROUND 20-25 KTS...WITH THE POSSIBILITY TO TAP 40 KT WINDS FROM APPROX 850 MB AS BOUNDARY LAYER MIXES OUT. A WIND ADVISORY MAY BE NEED FOR A TIME IN THE LATE MORNING TO EARLY EVENING HOURS ON WEDNESDAY. ADDITIONALLY...SOME LIGHT SNOW SHOWERS MAY WRAP AROUND AND AFFECT MAINLY NORTHERN PORTIONS OF THE FORECAST AREA WEDNESDAY NIGHT AS THE UPPER TROUGH FINALLY PASSES THROUGH. NOT CURRENTLY EXPECTING MUCH IN THE WAY OF ACCUMULATION. ANOTHER UPPER TROUGH AND COLD FRONT PUSHES INTO THE THROUGH THE AREA LATE THURSDAY INTO THURSDAY NIGHT...BRINGING AN ADDITIONAL CHANCE FOR SNOW AND FALLING TEMPS. && .LONG TERM /SATURDAY THROUGH TUESDAY/... ISSUED AT 305 AM EST WED JAN 30 2013 MODELS KEEP A BROAD UPPER TROUGH ACROSS EASTERN CANADA...GREAT LAKES AND NORTHEAST U.S. THROUGH THE PERIOD. THERE ARE A COUPLE OF WEAK UPPER DISTURBANCES THAT WILL ROTATE ACROSS OUR AREA WITH ONE OCCURRING AROUND SATURDAY...ANOTHER ONE LATE MONDAY AND THE EURO HAS ONE OCCURRING LATE TUESDAY...WHICH THE GFS DOES NOT. CONFIDENCE OF TUESDAY SYSTEM IS VERY LOW...HOWEVER ALL MODELS HAVE TRENDED WITH HIGHER POPS THEN...SO WILL ADD SLIGHT CHANCE OF SNOW SHOWERS DAY 7. OTHERWISE ALL BLEND POPS SEEM REASONABLE IN MOST OTHER CASES. AS FAR AS TEMPERATURES ARE CONCERNED MODELS HAVE TRENDED A LITTLE COLDER OVER THE WEEKEND AND TUESDAY. IN MOST CASES WENT WITH A BLEND OF ALL BLEND AND CONSALL NUMBERS. && .AVIATION /DISCUSSION FOR THE 30/06Z TAF ISSUANCE/... ISSUED AT 1055 PM EST TUE JAN 29 2013 SEVERE SQUALL LINE ACROSS EASTERN ILLINOIS AND SOUTHEASTERN MISSOURI LATE THIS EVENING WILL BE NEAR IND AND BMG AROUND ISSUANCE TIME...AND WITH TORNADO WATCH IN EFFECT FOR BMG...WILL GO WITH A TEMPO 40 KNOT SUSTAINED AND 50 KNOT GUST THROUGH 09Z WITH OTHERWISE SOUTHWWEST WINDS AROUND 20 KNOTS WITH GUSTS TO 35 KNOTS THE REMAINDER OF THE NIGHT. WINDS WILL SHIFT TO SOUTHWEST AND WEST AND THE SOLID RAINS SHOULD END BEHIND THE COLD FRONT THAT SHOULD MOVE THROUGH AROUND 12Z AT HUF AND HUF AND 14Z AT IND AND BMG. WINDS WHOULD STAY UP THROUGH THE ENTIRE TAF PERIOD BUT SLIGHTLY DECREASE IN SPEED AT IND AFTER 06Z THURSDAY. BASED ON LIGHTNING DATA...WILL GO WITH TEMPO THUNDERSTORMS AT IND AND BMG THROUGH 09Z AND THE OTHER SITES ONLY UNTIL 07Z. COULD SEE SOME MORE SHOWERS THIS AFTERNOON POSSIBLY MIXED WITH SNOW LATE...BUT COVERAGE APPEARS TOO LOW TO MENTION IN TAFS AT LEAST AT THIS TIME. MVFR CONDITIONS...EXCEPT IFR IN THUNDERSTORMS TO BECOME VFR AFTER 15Z PER MODEL TIME SECTIONS. && .IND WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH WEDNESDAY MORNING FOR INZ021-028>031-035>049- 051>057-060>065-067>072. && $$ SYNOPSIS...MRD NEAR TERM...MRD/TDUD SHORT TERM...MRD LONG TERM....JH AVIATION...MK
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1055 PM EST TUE JAN 29 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 337 PM EST TUE JAN 29 2013 NUMEROUS WEATHER HAZARDS WILL ACCOMPANY AN EXTREMELY POTENT SYSTEM IMPACTING THE REGION THROUGH TOMORROW. VERY UNSEASONABLY WARM AND MOIST CONDITIONS WILL BE IN PLACE THROUGH TONIGHT. AHEAD OF A STRONG COLD FRONT SWEEPING THROUGH THE REGION...THE POTENTIAL WILL EXIST FOR THUNDERSTORMS...HEAVY RAINFALL...FLOODING AND DAMAGING WINDS. POTENTIAL FOR STRONG WINDS WILL CONTINUE BEHIND THE FRONTAL BOUNDARY ON WEDNESDAY...AND FLOODING MAY LAST FOR SEVERAL DAYS OR MORE. && .NEAR TERM /REST OF TONIGHT/... ISSUED AT 942 PM EST TUE JAN 29 2013 UPDATE... LINE OF STRONG TO SEVERE THUNDERSTORMS IS WELL OUT AHEAD OF THE COLD FRONT AND CURRENTLY PUSHING EASTWARD THROUGH ILLINOIS AND WESTERN KENTUCKY. TEMPS ACROSS CENTRAL INDIANA HAVE BEEN SLOWLY RISING A FEW DEGREES OVER THE LAST FEW HOURS AS STRONG LOW LEVEL JET ADVECTS WARM AIR AHEAD OF IT. SO...LOSS OF DIURNAL HEATING HAS HAD LITTLE AFFECT ON ENVIRONMENT. INSTABILITY LOOKS MOST FAVORABLE FOR SEVERE STORMS ACROSS THE SOUTHERN PORTIONS OF FORECAST AREA PER LATEST LAPS ANALYSES. PREVIOUS DISCUSSION... FOCUS OF THE NEAR TERM REMAINS ON SEVERE WEATHER CHANCES AS WELL AS POSSIBLE HEAVY RAINFALL/FLOODING POSSIBILITIES TONIGHT. THE PERIOD BEGINS WITH GOOD SHORT TERM MODEL AGREEMENT AS TO THE LOCATION OF KEY FEATURES THAT MAY BRING POSSIBLE SEVERE TO PORTIONS OF THE FORECAST AREA TONIGHT. AT 00Z/WED...THE LOW PRESSURE CENTER IS PROGGED TO BE OVER CENTRAL MISSOURI...WITH ONGOING CONVECTION POSSIBLY ALREADY IN THE FORM OF A SQUALL LINE ALONG A STRONG COLD FRONT STRETCHED FROM NORTHWEST ILLINOIS...DOWN THROUGH CENTRAL MISSOURI...INTO EASTERN OKLAHOMA/WESTERN ARKANSAS. THERE DOES APPEAR TO BE SOME DIFFERENCES IN SPEED/TIMING OF THE FRONT INTO THE FORECAST AREA...WITH THE HRRR AND RAP INTO THE AREA A BIT QUICKER THE THE NAM AND GFS. PERSONAL EXPERIENCE HAS SHOWN THAT THESE COLD FRONT/SQUALL LINE FEATURES TEND TO COME IN A BIT QUICKER THAN SOMETIMES EXPECTED. THEREFORE...DECIDED TO TREND TOWARD THE HRRR/RUC SOLNS. AS WAS MENTIONED IN PREVIOUS DISCUSSIONS...DYNAMICS WILL NOT BE AN ISSUE WITH THIS SYSTEM AS THE FRONT APPROACHES. A LOW LEVEL JET AOA 80 KTS AT 850 MB IS EXPECTED TO DEVELOP OUT AHEAD OF THE FRONT THIS EVENING AND WILL TRANSLATE INTO OUR AREA TONIGHT. WITH 50 KT WINDS LOCATED APPROXIMATELY 1000-1500 FEET ABOVE THE SURFACE TONIGHT...DAMAGING WINDS MAY BECOME A REAL THREAT WITH ANY STORMS THAT ARE ABLE TO REMAIN ORGANIZED AS THEY PUSH INTO THE FORECAST AREA. ONE LIMITING FACTOR FOR CONVECTION REMAINING ORGANIZED INTO THE OVERNIGHT HOURS IS INSTABILITY. SFC-BASED CAPE LOOKS TO BE IN THE UNDER 200 J/KG RANGE...WHILE MUCAPE GIVES SLIGHTLY HIGHER VALUES OF 200-400 J/KG AS THE FRONT MOVES INTO THE AREA. WITH THE STRONG DYNAMICS AVAILABLE...WILL CONTINUE DAMAGING WINDS REFERENCE IN THE GRIDS. ALSO KEEP IN MIND THAT WITH AMPLE LOW LEVEL SHEAR...0-1 HELICITIES AOA 400-500 M2/S2...AN ISOLATED TORNADO CANNOT BE RULED OUT. THE BEST TIMING FOR SEVERE LOOKS TO START AT APPROXIMATELY 04-05Z ACROSS WESTERN PORTIONS OF THE FORECAST AREA...TO ABOUT 10-11Z OVER THE EAST. JUST ONE OTHER NOTE TO MENTION...THE HRRR ILLUSTRATES A LINE OF CONVECTION DEVELOPING OUT AHEAD OF THE MAIN SQUALL LINE. TO A LESSER EXTENT...THE RAP ALSO DEPICTS A SIMILAR SCENARIO. WHILE THIS FORECAST HAS TAKEN THIS INTO CONSIDERATION...IT COULD STILL ALLOW FOR AN EARLIER ONSET THAN FORECAST. HEAVY RAINFALL IS ALSO IN PLAY TONIGHT AS MOISTURE HAS CONTINUED TO STREAM NORTH INTO THE AREA. A PACIFIC TROPICAL PLUME OF MOISTURE HAS BEEN EVIDENT ALL DAY ON WATER VAPOR IMAGERY STREAMING NORTHWEST INTO LOWER MISSOURI/MID MISSISSIPPI/OHIO RIVER VALLEY STATES. COUPLE THAT WITH 60 DEGREE DEWPOINTS CURRENTLY ON THE SOUTHWESTERN DOORSTEP OF THE FORECAST AREA. PWATS TONIGHT AHEAD OF THE FRONT LOOK TO REACH UPWARDS OF 1.40-1.50 INCHES...YIELDING A PERCENT OF NORMAL OF AROUND 300 PERCENT. WOULD NOT BE SURPRISED TO SEE A WIDESPREAD 1 TO 1.5 INCH RAINFALL...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... ISSUED AT 337 PM EST TUE JAN 29 2013 SHORT TERM PERIOD SEES A DIFFERENT SET OF CHALLENGES. ONE OF THE INITIAL CHALLENGES WILL BE STRONG WINDS AFTER THE COLD FRONT SWEEPS THROUGH THE AREA AND A DRY SLOT APPROACHES THE FORECAST AREA DURING THE AFTERNOON HOURS. SUSTAINED WINDS AROUND 20-25 KTS...WITH THE POSSIBILITY TO TAP 40 KT WINDS FROM APPROX 850 MB AS BOUNDARY LAYER MIXES OUT. A WIND ADVISORY MAY BE NEED FOR A TIME IN THE LATE MORNING TO EARLY EVENING HOURS ON WEDNESDAY. ADDITIONALLY...SOME LIGHT SNOW SHOWERS MAY WRAP AROUND AND AFFECT MAINLY NORTHERN PORTIONS OF THE FORECAST AREA WEDNESDAY NIGHT AS THE UPPER TROUGH FINALLY PASSES THROUGH. NOT CURRENTLY EXPECTING MUCH IN THE WAY OF ACCUMULATION. ANOTHER UPPER TROUGH AND COLD FRONT PUSHES INTO THE THROUGH THE AREA LATE THURSDAY INTO THURSDAY NIGHT...BRINGING AN ADDITIONAL CHANCE FOR SNOW AND FALLING TEMPS. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ISSUED AT 144 PM EST TUE JAN 29 2013 .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE EXTENDED PERIOD WILL NOT BE NEARLY AS ACTIVE AS THE FIRST FEW DAYS OF THE FORECAST. FIRST OFF A SHORT WAVE TROUGH MOVING THROUGH THE GREAT LAKES REGION MAY BRING A FEW SNOW SHOWERS TO CENTRAL INDIANA AT THE BEGINNING OF THIS PERIOD. TEMPS/THICKNESS ALL LOOK COLD ENOUGH FOR PLAIN SNOW DURING THIS TIME. ATTM ACCUMULATIONS APPEAR TO BE AN INCH OR LESS. AFTER A COLD SHOT OF AIR THU AND FRIDAY...TEMPERATURES WILL GRADUALLY MODERATE TO CLIMO OVER THE WEEKEND AND INTO NEXT WEEK. SECOND HALF OF THE WEEKEND LOOKS DRY AND INTO EARLY NEXT WEEK. ENSEMBLES SHOW SOME PRECIP BY NEXT MONDAY/MONDAY NIGHT. TEMPERATURES LOOK WARM ENOUGH FOR A SNOW/RAIN MIX ACROSS A GOOD PORTION OF THE AREA. HAVE SMALL MINIMAL PRECIP CHANCES IN DURING THIS TIME. && .AVIATION /DISCUSSION FOR THE 30/06Z TAF ISSUANCE/... ISSUED AT 1055 PM EST TUE JAN 29 2013 SEVERE SQUALL LINE ACROSS EASTERN ILLINOIS AND SOUTHEASTERN MISSOURI LATE THIS EVENING WILL BE NEAR IND AND BMG AROUND ISSUANCE TIME...AND WITH TORNADO WATCH IN EFFECT FOR BMG...WILL GO WITH A TEMPO 40 KNOT SUSTAINED AND 50 KNOT GUST THROUGH 09Z WITH OTHERWISE SOUTHWWEST WINDS AROUND 20 KNOTS WITH GUSTS TO 35 KNOTS THE REMAINDER OF THE NIGHT. WINDS WILL SHIFT TO SOUTHWEST AND WEST AND THE SOLID RAINS SHOULD END BEHIND THE COLD FRONT THAT SHOULD MOVE THROUGH AROUND 12Z AT HUF AND HUF AND 14Z AT IND AND BMG. WINDS WHOULD STAY UP THROUGH THE ENTIRE TAF PERIOD BUT SLIGHTLY DECREASE IN SPEED AT IND AFTER 06Z THURSDAY. BASED ON LIGHTNING DATA...WILL GO WITH TEMPO THUNDERSTORMS AT IND AND BMG THROUGH 09Z AND THE OTHER SITES ONLY UNTIL 07Z. COULD SEE SOME MORE SHOWERS THIS AFTERNOON POSSIBLY MIXED WITH SNOW LATE...BUT COVERAGE APPEARS TOO LOW TO MENTION IN TAFS AT LEAST AT THIS TIME. MVFR CONDITIONS...EXCEPT IFR IN THUNDERSTORMS TO BECOME VFR AFTER 15Z PER MODEL TIME SECTIONS. && .IND WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH WEDNESDAY MORNING FOR INZ021-028>031-035>049- 051>057-060>065-067>072. && $$ SYNOPSIS...MRD NEAR TERM...MRD/TDUD SHORT TERM...MRD LONG TERM....SMF AVIATION...MK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1147 PM CST TUE JAN 29 2013 .UPDATE... ADDED 06Z TAF DISCUSSION. THERE WILL BE LITTLE CHANGE IN THINKING WITH A TOKEN EVENING UPDATE TO FIT CURRENT OBS. WAS ORIGINALLY THINKING THAT FORECAST AMOUNTS MAY BE TOO HIGH ON NW FRINGE OF FORECAST PRECIP SHIELD...HOWEVER 00Z NAM IS NOW PLACING HEAVIEST SNOWFALL AXIS SW-NE RIGHT THROUGH DES MOINES. FAR NW FRINGE OF ADVISORY MAY BE OVERDONE...BUT STILL LOOKS LIKE FORT DODGE AND MASON CITY AREAS MAY BE BRUSHED...ESPECIALLY SRN PORTIONS OF THOSE COUNTIES. NO CHANGES IN HEADLINES WHICH CONFIDENCE IN ANY PARTICULAR SOLUTION NOT GREAT ENOUGH TO CHANGE THINGS. LOOKED TO THE RAP FOR GUIDANCE BUT PAST SEVERAL RUNS ARE LITTLE HELP AS THEY HAVE BEEN CONSISTENTLY TOO AGGRESSIVE IN TIMING AND STRENGTH WITH PRECIP ONSET INTO IA. 00Z H85 ANALYSIS SHOWS STRONG WARM/MOIST ADVECTION INTO ST JOESPH/KC METRO AREAS AND TOPS ARE COOLING THERE SO SEE LITTLE REASON TO DOUBT PREVIOUS THINKING WITH PRECIP BLOSSOMING SHORTLY AND THAT APPEARS TO BE THE CASE. RADAR ECHOES ARE STRENGTHENING AND VIRGA DONUT SHRINKING. DUAL POL RADAR PRODUCTS SHOW RAIN/SNOW LINE ROUGHLY ALONG BEDFORD-OSCEOLA-NEWTON LINE SO SHOULD SEE ONLY SNOW TO N AND W OF THESE AREAS. PREVIOUS 00Z UPDATE...ADJUSTED FORECAST AND HEADLINES TO NOT START UNTIL 03Z BASED ON LATEST MODEL GUIDANCE AND OBSERVATIONAL TRENDS. WILL OBVIOUSLY RE-EXAMINE FORECAST FURTHER AFTER 00Z MODELS COME IN AND SYSTEM STARTS TO SHOW ITS HAND MORE UPSTREAM INTO NE AND KS. ADDED 00Z TAF DISCUSSION. && .SHORT TERM /TONIGHT/... UPPER WAVE EVIDENT ON WATER VAPOR DIGGING ALONG THE US/MEXICO BORDER AND STARTING TO LIFT NORTHEASTWARD INTO THE TEX PANHANDLE...TO CONTINUE ITS CURRENT TRAJECTORY NORTHEASTWARD THROUGH THE CENTRAL PLAINS AND INTO THE MID MISSISSIPPI VALLEY BY EARLY WEDNESDAY. THE STATE BECOMES SANDWICHED BETWEEN COUPLED JET STREAKS ALOFT...WITH STRONGEST FRONTOGENETICAL LIFT SHOWING UP ACROSS THE SOUTHEASTERN HALF OF THE CWA LATE THIS EVENING INTO THE OVERNIGHT HOURS. TROWAL FEATURE TO ROTATE EASTWARD THROUGH CENTRAL/SOUTHEASTERN CWA...WITH INCREASING MOISTURE IN THE LOW/MID LEVELS. DRIER AIR WORKING ITS WAY INTO THE NORTH SHOULD YIELD A SHARP CUTOFF IN THE SNOW FIELD TO THE NORTHWEST...WITH THE NORTHWESTERN CUTOFF TO THE HEAVIER SNOW FROM NEAR CORNING NORTHEASTWARD TO WAVERLY. HEAVIEST AMOUNTS EXPECTED ACROSS THE FAR SOUTHEASTERN CWA...WHERE QPF WILL BE GREATER AND COULD SEE SOME WEAK INSTABILITY ALOFT ENHANCE SNOWFALL RATES AT TIMES LATE TONIGHT. OVERALL THREE TO FOUR INCHES OF SNOW EXPECTED TO FALL ACROSS THE SOUTHEASTERN HALF OF THE CWA BY 12Z WEDNESDAY. SFC PRES GRADIENT TO TIGHTEN ON THE BACKSIDE OF THIS SYSTEM...WITH STRONG CAA. 925MB TO 850MB WINDS EXPECTED TO BE IN THE 30 TO 35KT RANGE BY LATE TONIGHT...WITH THESE WINDS TRANSLATING TO THE SURFACE WITH THE STRONG CAA. THEREFORE EXPECTING SUSTAINED WINDS IN THE 20 TO 30 MPH RANGE...WITH GUSTS TO 35 MPH OR HIGHER BY LATE TONIGHT ACROSS THE AREA. THIS WILL LEAD TO CONSIDERABLE BLOWING SNOW IN OPEN AREAS. ADDITIONALLY WITH THE RESIDUAL SURFACE MOISTURE AROUND...AND POSSIBILITY OF HEAVY WET SNOW INITIALLY BEFORE THE DRIER AIR WORKS INTO THE AREA RESULTING IN A LIGHTER FLUFFIER SNOW...SOME ICING MAY OCCUR ON ROADWAYS...TREES BRANCHES...AND POWER LINES. THEREFORE WILL CONTINUE THE WINTER HEADLINES AS THEY ARE FOR TONIGHT INTO WEDNESDAY MORNING. .LONG TERM /WEDNESDAY THROUGH TUESDAY/... RAPIDLY DEEPENING LOW PRESSURE WILL BE OVER CENTRAL ILLINOIS BY 12Z AND WILL SHIFT NORTHEAST INTO LOWER MICHIGAN BY 18Z. PV ANOMALY CURRENTLY OVER WEST CENTRAL TEXAS WILL BE ENTERING SOUTHEAST IOWA AS WELL BY 12Z WITH STRONG QG FORCING CONTINUING THROUGH MID TO LATE MORNING OVER THE SOUTHEAST. A PORTION OF THE WARM CONVEYOR WILL CONTINUE TO SUPPLY MOISTURE INTO THE SOUTHEAST EARLY IN THE PERIOD BEFORE DRIER AIR ADVECTS IN BY MID TO LATE MORNING. BEST SNOW ACCUMULATIONS WILL OCCUR THROUGH 15Z THEN DIMINISHING AFTER THAT TIME. THE MOST DIFFICULT PORTION OF THE SNOW FORECAST REMAINS THE NORTHWEST EDGE. ANY SHIFT SOUTHEAST OF THE STORM TRACK WOULD REDUCE SNOWFALL AMOUNT IN THESE REGIONS. THE STRONG WIND POTENTIAL WITH THIS SYSTEM WEDNESDAY MORNING REMAINS HIGH. IN ADDITION TO A TIGHT PRESSURE GRADIENT OF 30 TO 40 UBARS/KM...THE STRONG COLD ADVECTION WILL KEEP WINDS MIXED UP TO 900 MB WITH 35 TO 40 KTS AVAILABLE IN THAT MIXED LAYER. THE COLD ADVECTION WILL LEAD TO GOOD MOMENTUM TRANSFER OF THE WINDS WITH STRONGEST WINDS OCCURRING 12-18Z. AREAS WITH 2-3 INCHES OF SNOW OR MORE WILL HAVE SIGNIFICANT BLOWING SNOW WEDNESDAY MORNING THAT COULD APPROACH BLIZZARD CRITERIA. IN ADDITION...WITH WARMER NEAR SFC TEMPERATURES...THE SNOW FALL COULD HAVE SIMILAR PROPERTIES TO THAT OF THE DECEMBER BLIZZARD INITIALLY IN THAT IT WILL MELT THEN FREEZE UNDER THE FALLING SNOW RESULTING IN AN ICY SUB LAYER. THIS WOULD MAKE TRAVEL EXTREMELY HAZARDOUS THROUGH THIS EVENT. THE ACCUMULATING SNOW WILL END BY NOON WITH STEADY OR FALLING TEMPERATURES THE REMAINDER OF THE DAY. TEMPERATURES WILL BE COLD WEDNESDAY NIGHT WITH LOWS BELOW ZERO NORTH THOUGH LINGERING CLOUDS COULD HOLD TEMPERATURES UP OVERALL. ANOTHER UPPER WAVE WILL PUSH THROUGH WEDNESDAY NIGHT AND THURSDAY MORNING WITH AN ARCTIC BOUNDARY MOVING THROUGH THURSDAY AS WELL. WIND CHILL VALUES BY WEDNESDAY NIGHT AND THURSDAY WILL APPROACH 25 BELOW OVER NORTHERN IOWA DURING THIS PERIOD. CURRENTLY HAVE FLURRIES IN THE FORECAST FOR THURSDAY BUT THIS WILL NEED TO BE REEVALUATED FOR POTENTIAL OF VERY LIGHT SNOWFALL WITH A BRIEF PERIOD OF SATURATION AND LIFT THROUGH THE DENDRITIC LAYER. ARCTIC HIGH PRESSURE WILL DROP SOUTHEAST INTO THE STATE THURSDAY NIGHT. OVERNIGHT LOW TEMPERATURE WELL BELOW ZERO ARE EXPECTED. POSSIBLE TO BE WELL BELOW GUIDANCE WHERE THE NEW SNOW PACK IS. ANOTHER UPPER LEVEL SYSTEM WILL FOLLOW THE HIGH PRESSURE DEPARTURE BY FRIDAY AFTERNOON. ANOTHER PERIOD OF VERY LIGHT SNOW MAY OCCUR WITH THE SYSTEM PASSAGE. GRADUAL WARMING INTO THE WEEKEND WITH TEMPERATURES PUSHING INTO THE 20S AND 30S. THE NEXT UPPER WAVE DROPPING THROUGH NORTHWEST FLOW WILL ARRIVE MONDAY AND WILL DROP ANOTHER PUSH OF COLD AIR INTO THE STATE. THE COLD AIR WILL BE SHORT LIVED WITH RIDGING BUILDING INTO FROM THE WEST BY TUESDAY. && .AVIATION...30/06Z CONFIDENCE IN NEAR BLIZZARD CONDITIONS IS WANING SOMEWHAT. DEEP VERY STRONG FORCING UPSTREAM IS NOT RESULTING IN SNOW VISIBILITY AS LOW AS EXPECTED. THUS STILL HAVE IFR/LIFR CONDITIONS IN THE FORECAST...BUT MORE INFLUENCED BY CIGS RATHER THAN LIFR VSBYS. STILL EXPECT WIND GUSTS 25-30KTS HOWEVER. ALTHOUGH LOWER VSBYS IN SNOW SHOULD END BY MIDDAY...AT LEAST MVFR CIGS AND SOME FLURRIES SHOULD LINGER THROUGH THE AFTERNOON WITH WINDS DIMINISHING BY THAT TIME AS WELL. && .DMX WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING FROM 9 PM THIS EVENING TO NOON CST WED ADAIR-ADAMS-BLACK HAWK-BOONE-BREMER-BUTLER-CLARKE-DALLAS-DECATUR- GRUNDY-HARDIN-JASPER-MADISON-MARSHALL-POLK-RINGGOLD-STORY-TAMA- TAYLOR-UNION-WARREN-APPANOOSE-DAVIS-LUCAS-MAHASKA-MARION-MONROE- POWESHIEK-WAPELLO-WAYNE WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO NOON CST WED AUDUBON-CARROLL-CASS-CERRO GORDO-FRANKLIN-GREENE-GUTHRIE-HAMILTON- WEBSTER-WRIGHT && $$ UPDATE/AVIATION...SMALL SHORT TERM...BEERENDS LONG TERM...DONAVON
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1134 PM CST TUE JAN 29 2013 .DISCUSSION... SEE PREV DISCUSSION. && .AVIATION... DEFORMATION BAND OF SNOW HAS FORMED TO THE WEST OF THE TERMINALS...AND THE RAP AND NAM CONTINUE TO SHOW THIS BAND MOVING ACROSS NORTHEAST KANSAS OVERNIGHT. TIMING IS SEVERAL HOURS SLOWER FROM THE PREV FORECAST WITH SNOW LIKELY PERSISTING AT TOP AND FOE UNTIL 14Z. MODELS ALSO SUGGEST A LACK OF ICE IN THE TOP OF THE CLOUD INITIALLY. WITH SEVERAL REPORTS OF PL UPSTREAM...HAVE INTRODUCED A MIX OF -SNPL UNTIL THE BETTER DEFORMATION BAND MOVES IN AND SATURATES THE DENDRITIC GROWTH ZONE FOR A PERIOD OF MODERATE SNOW. CONFIDENCE IS HIGH THAT THERE WILL BE IFR AND LIFR CONDITIONS DURING THE NEXT 8 TO 12 HOURS. WOLTERS && .PREV DISCUSSION... /957 PM CST TUE JAN 29 2013/ A BAND OF SNOW HAS DEVELOPED ACROSS SOUTHWESTERN AND CENTRAL KANSAS WITHIN THE DEFORMATION ZONE OF THE UPPER TROUGH. THE LATEST RAP AND NAM PROGS SUGGEST THIS BAND OF SNOW WILL CONTINUE TO MOVE EAST AND NORTHEAST ACROSS THE NORTHERN TWO THIRDS OF THE FORECAST AREA...WITH THE HEAVIEST BAND SETTING UP NORTH OF AN ABILENE TO HOLTON LINE. MODELS HAVE ALSO TRENDED SOUTH WITH THE SNOW ACCUMULATIONS AND SHOW A COUPLE INCHES POSSIBLE ALONG INTERSTATE 70. WITH MODELS STILL SHOWING DECENT FRONTOGENETICAL FORCING AND THE DEFORMATION BAND HAVING ALREADY FORMED...HAVE EXPANDED THE ADVISORY A LITTLE FURTHER SOUTH TO INCLUDE DICKINSON...GEARY...MORRIS AND WABAUNSEE COUNTIES. WOLTERS /556 PM CST TUE JAN 29 2013/ 21Z RAP AND 18Z NAM HAVE STARTED TO SHOW SOME INDICATION OF A DECENT FRONTOGENETICAL BAND DEVELOPING MAINLY DURING THE 06Z TO 12Z TIME FRAME. WITH RECENT RADAR TRENDS SHOWING A BAND STARTING TO FORM ACROSS WESTERN KS...AM BEGINNING TO THINK THAT MODELS ARE DOING A REASONABLE JOB DEPICTING THE SYSTEM AS IT LIFTS OUT OVERNIGHT. CONFIDENCE IS INCREASING THAT THERE WILL BE SNOW. SNOW AMOUNTS SEEM TO BE IN THE BALLPARK INITIALLY. WITH SOME UNCERTAINTY FROM THE PREV FORECAST ABOUT MESOSCALE FORCING...THINK THAT FORECAST SNOW AMOUNTS ARE PROBABLY NOT ON THE LOW SIDE. THERE ARE STILL SOME QUESTIONS WITH SOME INDICATIONS OF MID LEVEL DRY AIR COMING IN AT THE DENDRITIC GROWTH ZONE AND A GENERAL LACK OF INSTABILITY OF CONDITIONAL INSTABILITY THAT COULD ACT TO KEEP SNOW AMOUNT ON WITHIN THE FORECASTED VALUES. IF ANYTHING WILL NEED TO WATCH THINGS PROGRESS AND POTENTIALLY EXPAND THE ADVISORY IF INDEED A BAND OF MODERATE SNOW MOVES ACROSS THE AREA. MODELS CONTINUE TO SHOW A STRENGTHENING PRESSURE GRADIENT WITH NORTH AND NORTHWEST WINDS GUSTING UP TO 35 MPH. WOLTERS /328 PM CST TUE JAN 29 2013/ THE ABRUPT RETURN TO WINTER CONTINUES TODAY ACROSS THE FORECAST AREA...AFTER A ROUND OF MORNING SHOWERS AND THUNDERSTORMS FOR EASTERN PORTIONS OF THE STATE. THE DEEP LONGWAVE TROF CONTINUES TO MOVE EASTWARD ACROSS THE ROCKY MOUNTAINS AND INTO THE HIGH PLAINS. ENERGY ROTATING THROUGH THE TX PANHANDLES AIDING IN ENHANCING A NEGATIVE TILT TO THE SOUTHERN STREAM AS IT LIFTS INTO OUR AREA THIS EVENING AND OVERNIGHT. HAVE EXPANDED THE WINTER WEATHER ADVISORY BOTH WEST AND SOUTH A FEW COUNTIES. STILL APPEARS AS IF FAR NE COUNTIES WILL GET THE HIGHER SNOW AMOUNTS WHERE BAND OF FRONTOGENESIS TRACKS WEST TO EAST GENERALLY NORTH OF THE INTERSTATE...AS DOES THE MID LEVEL DEFORMATION ZONE. HARD TO SEE A TIME WHEN ALL INGREDIENTS COME TOGETHER FOR A BANDED HEAVY SNOW EVENT...ALTHOUGH AROUND 06Z NORTH OF THE MHK AREA DO SEE SOME FRONTOGENETIC FORCING ALIGNED WITH SOME NEGATIVE EPV...THEREFORE INCREASED SNOW TOTALS FOR THIS AREA. 2-3 INCH LINE RUNS GENERALLY ALONG THE INTERSTATE WITH DIMINISHING AMOUNTS SOUTH AND HIGHER NUMBERS NORTH AND EAST. STARTED ADVISORY WEST AT 6PM FOLLOWED BY AN 11PM START FOR COUNTIES FARTHER EAST. OF CONCERN ARE THE WINDS THAT ACCOMPANY THIS SYSTEM AS THE SNOW FALLS OVERNIGHT AND INTO THE EARLY COMMUTE TOMORROW MORNING. SNOW WILL REDUCE VISIBILITIES AND MAY MAKE ROADS DIFFICULT TO KEEP CLEAR...SO THAT EVEN A FEW INCHES OF SNOW MAY BRING TRAVEL PROBLEMS. SNOW SHOULD END BY 9AM AND WILL LIKELY END A FEW HOURS SOONER OUT WEST AND CAN ADJUST ADVISORY ENDING AS NEEDED. THURSDAY THROUGH NEXT TUESDAY...DRY WEATHER WILL LIKELY CONTINUE THROUGH THE REMAINDER OF THE FORECAST PERIOD AS COLD AND DRY AIR PLUNGES SOUTHWARD INTO THE CENTRAL PLAINS. NORTHWEST FLOW ALOFT ON THE EASTERN EDGE OF A STRONGLY AMPLIFIED RIDGE OVER THE WESTERN CONUS WILL PREVENT THE FORMATION OF ANY STRONG SURFACE TROUGH AND SUBSEQUENT WARM AIR ADVECTION THROUGH THE REST OF THE WORK WEEK. THE FIRST PUSH OF COLD AIR WILL ALSO LIKELY BE REINFORCED BY A SECOND PUSH OF COLD AIR ON THURSDAY NIGHT...WHICH MODELS CURRENTLY PROG TO BE CHARACTERIZED BY 850 MB TEMPERATURES AROUND -15 DEGREES C. THE COLDEST MORNING AT THIS TIME LOOKS TO BE FRIDAY MORNING...WHEN THE SURFACE HIGH ASSOCIATED WITH THE ARCTIC AIRMASS BECOMES CENTERED OVER NORTHEAST KANSAS. CURRENTLY THE FORECAST FOR FRIDAY MORNING REFLECTS SLIGHTLY LOWER TEMPS THAN THE PREVIOUS FORECAST SUGGESTED DUE TO THE FACT THAT SNOW FROM TUESDAY NIGHT/WED MORNING WILL LIKELY LINGER PREVENTING THE POLAR AIR FROM MODIFYING MUCH. GIVEN THAT SNOW WILL LIKELY STILL BE ON THE GROUND AND THAT SKIES WILL CLEAR AND WINDS WILL BE CALM...IN RESPONSE TO THE SURFACE HIGH...EXPECT FRIDAY MORNING TO BE VERY CHILLY...WITH LOWS IN THE SINGLE DIGITS TO LOWER TEENS. BY SATURDAY THE SURFACE HIGH WILL SLIDE EASTWARD AND SOUTHERLY RETURN FLOW WILL COMMENCE ON THE BACKSIDE OF THE HIGH. CONCURRENTLY THE AFOREMENTIONED WESTERN CONUS RIDGE MAY SHIFT EVER SO SLIGHTLY TO THE EAST...ALLOWING THE COLD AIR ASSOCIATED WITH THE BROAD HUDSON BAY LOW TO ALSO SHIFT EAST. THE BOTTOM LINE FOR THE WEEKEND AND INTO NEXT WEEK IS A GRADUAL WARMING TREND AS SURFACE WINDS WILL BE WESTERLY TO SOUTHWESTERLY...WHICH WILL INTRODUCE A SLIGHT DOWNSLOPE COMPONENT...AIDING IN SURFACE TEMP WARMING. AT THIS POINT MAX TEMPS LOOK TO RUN ABOUT 10 DEGREES ABOVE NORMAL FROM SUNDAY THROUGH NEXT TUESDAY...BUT THIS COULD CHANGE A FEW DEGREES EITHER WAY DEPENDING ON HOW FAST THE SNOW MELTS. JL && .TOP WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY TIL 7AM WED FOR KSZ008-009-020>022-034>037. WINTER WEATHER ADVISORY TIL 9AM WED KSZ010>012-023-024-026-038>040. && $$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
957 PM CST TUE JAN 29 2013 .DISCUSSION... A BAND OF SNOW HAS DEVELOPED ACROSS SOUTHWESTERN AND CENTRAL KANSAS WITHIN THE DEFORMATION ZONE OF THE UPPER TROUGH. THE LATEST RAP AND NAM PROGS SUGGEST THIS BAND OF SNOW WILL CONTINUE TO MOVE EAST AND NORTHEAST ACROSS THE NORTHERN TWO THIRDS OF THE FORECAST AREA...WITH THE HEAVIEST BAND SETTING UP NORTH OF AN ABILENE TO HOLTON LINE. MODELS HAVE ALSO TRENDED SOUTH WITH THE SNOW ACCUMULATIONS AND SHOW A COUPLE INCHES POSSIBLE ALONG INTERSTATE 70. WITH MODELS STILL SHOWING DECENT FRONTOGENETICAL FORCING AND THE DEFORMATION BAND HAVING ALREADY FORMED...HAVE EXPANDED THE ADVISORY A LITTLE FURTHER SOUTH TO INCLUDE DICKINSON...GEARY...MORRIS AND WABAUNSEE COUNTIES. WOLTERS && .AVIATION... WITH INCREASING CONFIDENCE IN SNOW MOVING IN FROM THE WEST...THERE IS INCREASED CONFIDENCE IN IFR AND LIFR CONDITIONS FORMING OVERNIGHT. AT THIS TIME...THE BEST GUESS FOR WHEN THE HEAVIER SNOW WILL OCCUR IS BETWEEN 04Z AND 11Z AT THE TERMINALS. BY 15Z THE FORCING LOOKS TO MOVE TO THE EAST OF THE AREA WITH CONDITIONS IMPROVING. WOLTERS && .PREV DISCUSSION... /556 PM CST TUE JAN 29 2013/ 21Z RAP AND 18Z NAM HAVE STARTED TO SHOW SOME INDICATION OF A DECENT FRONTOGENETICAL BAND DEVELOPING MAINLY DURING THE 06Z TO 12Z TIME FRAME. WITH RECENT RADAR TRENDS SHOWING A BAND STARTING TO FORM ACROSS WESTERN KS...AM BEGINNING TO THINK THAT MODELS ARE DOING A REASONABLE JOB DEPICTING THE SYSTEM AS IT LIFTS OUT OVERNIGHT. CONFIDENCE IS INCREASING THAT THERE WILL BE SNOW. SNOW AMOUNTS SEEM TO BE IN THE BALLPARK INITIALLY. WITH SOME UNCERTAINTY FROM THE PREV FORECAST ABOUT MESOSCALE FORCING...THINK THAT FORECAST SNOW AMOUNTS ARE PROBABLY NOT ON THE LOW SIDE. THERE ARE STILL SOME QUESTIONS WITH SOME INDICATIONS OF MID LEVEL DRY AIR COMING IN AT THE DENDRITIC GROWTH ZONE AND A GENERAL LACK OF INSTABILITY OF CONDITIONAL INSTABILITY THAT COULD ACT TO KEEP SNOW AMOUNT ON WITHIN THE FORECASTED VALUES. IF ANYTHING WILL NEED TO WATCH THINGS PROGRESS AND POTENTIALLY EXPAND THE ADVISORY IF INDEED A BAND OF MODERATE SNOW MOVES ACROSS THE AREA. MODELS CONTINUE TO SHOW A STRENGTHENING PRESSURE GRADIENT WITH NORTH AND NORTHWEST WINDS GUSTING UP TO 35 MPH. WOLTERS /328 PM CST TUE JAN 29 2013/ THE ABRUPT RETURN TO WINTER CONTINUES TODAY ACROSS THE FORECAST AREA...AFTER A ROUND OF MORNING SHOWERS AND THUNDERSTORMS FOR EASTERN PORTIONS OF THE STATE. THE DEEP LONGWAVE TROF CONTINUES TO MOVE EASTWARD ACROSS THE ROCKY MOUNTAINS AND INTO THE HIGH PLAINS. ENERGY ROTATING THROUGH THE TX PANHANDLES AIDING IN ENHANCING A NEGATIVE TILT TO THE SOUTHERN STREAM AS IT LIFTS INTO OUR AREA THIS EVENING AND OVERNIGHT. HAVE EXPANDED THE WINTER WEATHER ADVISORY BOTH WEST AND SOUTH A FEW COUNTIES. STILL APPEARS AS IF FAR NE COUNTIES WILL GET THE HIGHER SNOW AMOUNTS WHERE BAND OF FRONTOGENESIS TRACKS WEST TO EAST GENERALLY NORTH OF THE INTERSTATE...AS DOES THE MID LEVEL DEFORMATION ZONE. HARD TO SEE A TIME WHEN ALL INGREDIENTS COME TOGETHER FOR A BANDED HEAVY SNOW EVENT...ALTHOUGH AROUND 06Z NORTH OF THE MHK AREA DO SEE SOME FRONTOGENETIC FORCING ALIGNED WITH SOME NEGATIVE EPV...THEREFORE INCREASED SNOW TOTALS FOR THIS AREA. 2-3 INCH LINE RUNS GENERALLY ALONG THE INTERSTATE WITH DIMINISHING AMOUNTS SOUTH AND HIGHER NUMBERS NORTH AND EAST. STARTED ADVISORY WEST AT 6PM FOLLOWED BY AN 11PM START FOR COUNTIES FARTHER EAST. OF CONCERN ARE THE WINDS THAT ACCOMPANY THIS SYSTEM AS THE SNOW FALLS OVERNIGHT AND INTO THE EARLY COMMUTE TOMORROW MORNING. SNOW WILL REDUCE VISIBILITIES AND MAY MAKE ROADS DIFFICULT TO KEEP CLEAR...SO THAT EVEN A FEW INCHES OF SNOW MAY BRING TRAVEL PROBLEMS. SNOW SHOULD END BY 9AM AND WILL LIKELY END A FEW HOURS SOONER OUT WEST AND CAN ADJUST ADVISORY ENDING AS NEEDED. THURSDAY THROUGH NEXT TUESDAY...DRY WEATHER WILL LIKELY CONTINUE THROUGH THE REMAINDER OF THE FORECAST PERIOD AS COLD AND DRY AIR PLUNGES SOUTHWARD INTO THE CENTRAL PLAINS. NORTHWEST FLOW ALOFT ON THE EASTERN EDGE OF A STRONGLY AMPLIFIED RIDGE OVER THE WESTERN CONUS WILL PREVENT THE FORMATION OF ANY STRONG SURFACE TROUGH AND SUBSEQUENT WARM AIR ADVECTION THROUGH THE REST OF THE WORK WEEK. THE FIRST PUSH OF COLD AIR WILL ALSO LIKELY BE REINFORCED BY A SECOND PUSH OF COLD AIR ON THURSDAY NIGHT...WHICH MODELS CURRENTLY PROG TO BE CHARACTERIZED BY 850 MB TEMPERATURES AROUND -15 DEGREES C. THE COLDEST MORNING AT THIS TIME LOOKS TO BE FRIDAY MORNING...WHEN THE SURFACE HIGH ASSOCIATED WITH THE ARCTIC AIRMASS BECOMES CENTERED OVER NORTHEAST KANSAS. CURRENTLY THE FORECAST FOR FRIDAY MORNING REFLECTS SLIGHTLY LOWER TEMPS THAN THE PREVIOUS FORECAST SUGGESTED DUE TO THE FACT THAT SNOW FROM TUESDAY NIGHT/WED MORNING WILL LIKELY LINGER PREVENTING THE POLAR AIR FROM MODIFYING MUCH. GIVEN THAT SNOW WILL LIKELY STILL BE ON THE GROUND AND THAT SKIES WILL CLEAR AND WINDS WILL BE CALM...IN RESPONSE TO THE SURFACE HIGH...EXPECT FRIDAY MORNING TO BE VERY CHILLY...WITH LOWS IN THE SINGLE DIGITS TO LOWER TEENS. BY SATURDAY THE SURFACE HIGH WILL SLIDE EASTWARD AND SOUTHERLY RETURN FLOW WILL COMMENCE ON THE BACKSIDE OF THE HIGH. CONCURRENTLY THE AFOREMENTIONED WESTERN CONUS RIDGE MAY SHIFT EVER SO SLIGHTLY TO THE EAST...ALLOWING THE COLD AIR ASSOCIATED WITH THE BROAD HUDSON BAY LOW TO ALSO SHIFT EAST. THE BOTTOM LINE FOR THE WEEKEND AND INTO NEXT WEEK IS A GRADUAL WARMING TREND AS SURFACE WINDS WILL BE WESTERLY TO SOUTHWESTERLY...WHICH WILL INTRODUCE A SLIGHT DOWNSLOPE COMPONENT...AIDING IN SURFACE TEMP WARMING. AT THIS POINT MAX TEMPS LOOK TO RUN ABOUT 10 DEGREES ABOVE NORMAL FROM SUNDAY THROUGH NEXT TUESDAY...BUT THIS COULD CHANGE A FEW DEGREES EITHER WAY DEPENDING ON HOW FAST THE SNOW MELTS. JL && .TOP WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY TIL 7AM WED FOR KSZ008-009-020>022-034>037. WINTER WEATHER ADVISORY TIL 9AM WED KSZ010>012-023-024-026-038>040. && $$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1158 PM EST TUE JAN 29 2013 ...Updated Aviation Discussion... .Mesoscale Forecast Update... 1115 PM EST Tue Jan 30 2013 Updated the zones and other public products to include tornado watch number 12 which is in effect until 5 AM EST Wednesday. Forecast continues to be on target for the overnight period. Severe QLCS is in progress to the west of our area and is approaching the Wabash and Ohio Rivers in far western Kentucky. Upstream reports from WFO Paducah reveal quite a bit of wind damage with this linear system. Mesoscale analysis continues to show more than 70kts of effective shear which should increase a bit more over the next few hours. VAD wind profiles from PAH still show nearly 100kts of wind at 4000 ft AGL and calculating SRH from the VAD profiles show 0-1KM SRH of 550-650 M2/S2 and 0-3KM SRH of over 1000 M2/S2. Thus, with the shear and the strong theta-e advection mixing out the low-level inversion, this line should become more surface rooted and increase in intensity as it heads east. Damaging winds are very likely with this line overnight and embedded tornadoes within QLCS mesovortices and bowing line segments are likely. Based on current progression, this activity should be on our border with WFO PAH around 1230-130 AM EST and in the I-65 corridor including Louisville around 2-3 AM and then toward the I-75 between 3-5 AM EST. This is a little faster than previously indicated due to the fact that the line is speeding up a bit due to cold pool generation behind the line. Previously issued at 830 PM EST Tue Jan 30 2013 Surface low is beginning to strengthen across Missouri as upper-level energy pushes eastward. As of 800 PM, the cold front extends southwest from Lake Michigan, through Illinois, Missouri, and into Oklahoma. Convection has been ongoing this afternoon and evening ahead of the front. While there were severe storms that impacted the St. Louis metropolitan area earlier, but this has diminished in strength as it currently pushes into central Illinois. The airmass across central Illinois and into our area is still fairly stable. Aircraft soundings confirm what the models have been predicting, which is a low-level inversion. The main concern is the convection ongoing across south-central Missouri and northern Arkansas, which is showing better signs of organizing. As indicated with the latest Mesoscale Discussion from SPC, this will likely be the line that will continue to propagate east impacting our area overnight. As this line approaches, the cap will weaken as theta-e advection increases, which is evident with a few low-topped showers developing around the region. As advertised for several days now, the shear will be quite impressive as the line gets into our area. Effective bulk shear currently ahead of the line (across western KY) is 55+ knots, with effective SRH up to about 500 m2/s2. All guidance continues to peg high shear in a weakly unstable environment for us as this convective line gets into our area. With the surface low strengthening as it tracks northeast and 55+ knot winds at 1900 ft AGL, would expect the severe potential to continue into southern Indiana/central Kentucky. Damaging winds with the line will be the main threat as it becomes better organized over the next few hours. Embedded circulations within bowing segments will continue to be a threat as well, so isolated tornadoes remain in play. Overall timing has not changed, with models still showing slight timing differences. Latest RAP is a tad slower than our current forecast, but if the line surges with better cold pool forcing, then we are pretty much on schedule. Aside from the strong winds associated with the convection, gradient winds continue to strengthen. Some gusts are currently around 30 knots, with stronger winds likely as this system approaches. && .Short Term (Tonight through Wednesday Night)... Issued at 320 PM EST Tue Jan 29 2013 ...Strong to Severe Storms Expected Early Wednesday Morning With Wind Damage and Isolated Tornadoes Being The Main Threats... Models continue to remain in good agreement on severe weather threat for tonight, and upstream development is matching up well with high-res forecasts. MSAS analysis at 19Z indicated a broad 998 mb low, stretching from eastern OK to southwest MO. By 06Z tonight, models forecast this low to drop to around 990 mb near KLOT and continuing to deepen towards daybreak. A powerful low-level jet will develop overnight in response to this deepening. Models continue to indicate this jet will be on the order of 70-80 knots at 850 mb. Gradient winds ahead of the main line still are expected to be fairly gusty. Speeds are marginal for a wind advisory, but guidance usually does not handle nighttime winds as well in these situations, so will continue the wind advisory. Temperatures remaining in the 60s through the night will mean that a squall line that forms out of the storms to our west this afternoon will find a favorable environment to maintain itself through the forecast area. Low level wind shear is mostly unidirectional, but storm relative helicities are very high. We may see some discrete cells develop ahead of the line which would be able to take more advantage of more southerly winds ahead of the line to produce tornadoes. The line itself likely will produce damaging winds as the strong winds aloft get mixed down. Also cannot rule out some embedded tornadoes within the line in the stronger meso`s that form. The threat for flash flooding seems less with each run, as the width of the band thins out some. For now have QPF for the tonight/Wednesday time period at around an inch, though isolated higher amounts are possible. Area rivers should be able to handle this water. Guidance for winds behind the main line pick up again Wednesday afternoon. Should we get any breaks in the clouds, we easily could see another round of 30-40 knot winds, so current timing on the wind advisory looks good. The cold front associated with this low pressure system will not get into the region until late in the afternoon Wednesday. West/northwest winds will stay up Wednesday night as much colder air pours into the area. We may see a brief period of snow as lingering precipitation ahead of the main upper trough and nearer the front remains into the night. Accumulations look minor at this point, mainly over the Bluegrass if at all. .Long Term (Thursday through Tuesday)... Issued at 325 PM EST Tue Jan 29 2013 A shortwave and weak surface boundary looks to move through the Ohio Valley Thursday afternoon/evening, bringing a slight chance for light rain/snow showers to south-central Indiana. Once the temperatures drop below freezing that night, expect any rain showers to change over to snow completely as central Kentucky and southern IN gets locked under a cold, Canadian airmass. Since models appear to be trending a bit cooler, have dropped min temps Thursday overnight/Friday morning into the upper teens and lower 20s. These temps don`t look to rebound above the freezing mark on Friday afternoon so look for clearing skies as the disturbance moves off toward the east and surface high pressure briefly drops in. The next disturbance appears to begin affecting the northern and western portions of the forecast area by Saturday morning with light snow shower chances for the north and light rain showers elsewhere. As the temps rise above freezing, any snow that does fall early on should switch over to mostly rain as the entire thermal profile warms up. Even though temps will fall back into the 20s overnight Saturday, the precip should exit to the east before approaching the freezing mark again. For the remainder of the weekend, southerly flow will return to the region, warming temps into the 40s and 50s Sunday-Monday. However, the rain is anticipated to return ahead of a cold front Monday in the form of rain. The rain should be out by the start of the day on Tuesday with the frontal passage. This leads temps to take on a non-diurnal curve on Tuesday as the warmest temps of the day should occur early on. As always is the case for this time of year, any changes to the thermal profile forecast could change precip types but for now, there appears to be general model consensus in the anticipated overall pattern for this time frame. Any snow that is able to stick to surfaces should be very light in accumulations. && .Aviation (06Z TAF Issuance)... Issued at 1158 PM EST Tue Jan 29 2013 Deep upper trough over the Plains will drive a surface low pressure system from the Plains and into the Great Lakes during the day on Wednesday. Strong surface cold front is located to our west with a pre-frontal trough axis out ahead of the cold front. Quasi-linear convective system is well developed and located along the IN/IL/KY border area and heading east at around 50kts. Based on the latest radar data, this line will impact the KBWG terminal around 0630-0830Z. It should be reaching the KSDF terminal around 0700-0800Z and the KLEX terminal around 0900-1000Z. Have continued to advertise a period of VCTS just before the above mentioned times to account for any development that may occur ahead of the line. Will be keeping a very close met watch on the TAF`s tonight and will be updating to time the lines into the terminals as they approach. Feel that conditions will be quite poor when the squalls go through. Variable winds of 25G35kt will be possible for a time. LLWS will continue to be a problem until the main convective line passes. MVFR cigs will continue behind the line with conditions not improving until mid-late morning. Previous thinking of a second low-topped line of convection developing still looks like a possibility and we`ll address those issues in later forecasts. && .Hydrology... Issued at 300 AM EST Tue Jan 29 2013 No real changes in the forecast thinking on the hydrologic front. An intense line of strong to severe thunderstorms is forecast to move across the region late tonight and early Wednesday morning. In addition to the threat of damaging winds, these storms will likely produce heavy rainfall. Once the system pulls east on Wednesday morning, a period of stratiform rainfall will likely persist for a few hours. Rainfall amounts averaging a little more than an inch in 6 hours should be widespread. Isolated amounts of up to 2 inches are possible. This rain could result in brief small stream flooding and later rises on larger rivers. Any flooding that will occur should be minor due to the fast nature of these storms. The rain will taper to scattered showers Wednesday afternoon. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...WIND ADVISORY UNTIL 4 PM EST /3 PM CST/ WEDNESDAY FOR INZ076>079- 083-084-089>092. KY...WIND ADVISORY UNTIL 4 PM EST /3 PM CST/ WEDNESDAY FOR KYZ023>032- 061-062-070>072. WIND ADVISORY UNTIL 7 PM EST /6 PM CST/ WEDNESDAY FOR KYZ033>043- 045>049-053>057-063>067-073>078-081-082. $$ Mesoscale........MJ/MJP Short Term.......RJS Long Term........lg Aviation.........MJ Hydrology........CMC
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1118 PM EST TUE JAN 29 2013 .Mesoscale Forecast Update... 1115 PM EST Tue Jan 30 2013 Updated the zones and other public products to include tornado watch number 12 which is in effect until 5 AM EST Wednesday. Forecast continues to be on target for the overnight period. Severe QLCS is in progress to the west of our area and is approaching the Wabash and Ohio Rivers in far western Kentucky. Upstream reports from WFO Paducah reveal quite a bit of wind damage with this linear system. Mesoscale analysis continues to show more than 70kts of effective shear which should increase a bit more over the next few hours. VAD wind profiles from PAH still show nearly 100kts of wind at 4000 ft AGL and calculating SRH from the VAD profiles show 0-1KM SRH of 550-650 M2/S2 and 0-3KM SRH of over 1000 M2/S2. Thus, with the shear and the strong theta-e advection mixing out the low-level inversion, this line should become more surface rooted and increase in intensity as it heads east. Damaging winds are very likely with this line overnight and embedded tornadoes within QLCS mesovortices and bowing line segments are likely. Based on current progression, this activity should be on our border with WFO PAH around 1230-130 AM EST and in the I-65 corridor including Louisville around 2-3 AM and then toward the I-75 between 3-5 AM EST. This is a little faster than previously indicated due to the fact that the line is speeding up a bit due to cold pool generation behind the line. Previously issued at 830 PM EST Tue Jan 30 2013 Surface low is beginning to strengthen across Missouri as upper-level energy pushes eastward. As of 800 PM, the cold front extends southwest from Lake Michigan, through Illinois, Missouri, and into Oklahoma. Convection has been ongoing this afternoon and evening ahead of the front. While there were severe storms that impacted the St. Louis metropolitan area earlier, but this has diminished in strength as it currently pushes into central Illinois. The airmass across central Illinois and into our area is still fairly stable. Aircraft soundings confirm what the models have been predicting, which is a low-level inversion. The main concern is the convection ongoing across south-central Missouri and northern Arkansas, which is showing better signs of organizing. As indicated with the latest Mesoscale Discussion from SPC, this will likely be the line that will continue to propagate east impacting our area overnight. As this line approaches, the cap will weaken as theta-e advection increases, which is evident with a few low-topped showers developing around the region. As advertised for several days now, the shear will be quite impressive as the line gets into our area. Effective bulk shear currently ahead of the line (across western KY) is 55+ knots, with effective SRH up to about 500 m2/s2. All guidance continues to peg high shear in a weakly unstable environment for us as this convective line gets into our area. With the surface low strengthening as it tracks northeast and 55+ knot winds at 1900 ft AGL, would expect the severe potential to continue into southern Indiana/central Kentucky. Damaging winds with the line will be the main threat as it becomes better organized over the next few hours. Embedded circulations within bowing segments will continue to be a threat as well, so isolated tornadoes remain in play. Overall timing has not changed, with models still showing slight timing differences. Latest RAP is a tad slower than our current forecast, but if the line surges with better cold pool forcing, then we are pretty much on schedule. Aside from the strong winds associated with the convection, gradient winds continue to strengthen. Some gusts are currently around 30 knots, with stronger winds likely as this system approaches. && .Short Term (Tonight through Wednesday Night)... Issued at 320 PM EST Tue Jan 29 2013 ...Strong to Severe Storms Expected Early Wednesday Morning With Wind Damage and Isolated Tornadoes Being The Main Threats... Models continue to remain in good agreement on severe weather threat for tonight, and upstream development is matching up well with high-res forecasts. MSAS analysis at 19Z indicated a broad 998 mb low, stretching from eastern OK to southwest MO. By 06Z tonight, models forecast this low to drop to around 990 mb near KLOT and continuing to deepen towards daybreak. A powerful low-level jet will develop overnight in response to this deepening. Models continue to indicate this jet will be on the order of 70-80 knots at 850 mb. Gradient winds ahead of the main line still are expected to be fairly gusty. Speeds are marginal for a wind advisory, but guidance usually does not handle nighttime winds as well in these situations, so will continue the wind advisory. Temperatures remaining in the 60s through the night will mean that a squall line that forms out of the storms to our west this afternoon will find a favorable environment to maintain itself through the forecast area. Low level wind shear is mostly unidirectional, but storm relative helicities are very high. We may see some discrete cells develop ahead of the line which would be able to take more advantage of more southerly winds ahead of the line to produce tornadoes. The line itself likely will produce damaging winds as the strong winds aloft get mixed down. Also cannot rule out some embedded tornadoes within the line in the stronger meso`s that form. The threat for flash flooding seems less with each run, as the width of the band thins out some. For now have QPF for the tonight/Wednesday time period at around an inch, though isolated higher amounts are possible. Area rivers should be able to handle this water. Guidance for winds behind the main line pick up again Wednesday afternoon. Should we get any breaks in the clouds, we easily could see another round of 30-40 knot winds, so current timing on the wind advisory looks good. The cold front associated with this low pressure system will not get into the region until late in the afternoon Wednesday. West/northwest winds will stay up Wednesday night as much colder air pours into the area. We may see a brief period of snow as lingering precipitation ahead of the main upper trough and nearer the front remains into the night. Accumulations look minor at this point, mainly over the Bluegrass if at all. .Long Term (Thursday through Tuesday)... Issued at 325 PM EST Tue Jan 29 2013 A shortwave and weak surface boundary looks to move through the Ohio Valley Thursday afternoon/evening, bringing a slight chance for light rain/snow showers to south-central Indiana. Once the temperatures drop below freezing that night, expect any rain showers to change over to snow completely as central Kentucky and southern IN gets locked under a cold, Canadian airmass. Since models appear to be trending a bit cooler, have dropped min temps Thursday overnight/Friday morning into the upper teens and lower 20s. These temps don`t look to rebound above the freezing mark on Friday afternoon so look for clearing skies as the disturbance moves off toward the east and surface high pressure briefly drops in. The next disturbance appears to begin affecting the northern and western portions of the forecast area by Saturday morning with light snow shower chances for the north and light rain showers elsewhere. As the temps rise above freezing, any snow that does fall early on should switch over to mostly rain as the entire thermal profile warms up. Even though temps will fall back into the 20s overnight Saturday, the precip should exit to the east before approaching the freezing mark again. For the remainder of the weekend, southerly flow will return to the region, warming temps into the 40s and 50s Sunday-Monday. However, the rain is anticipated to return ahead of a cold front Monday in the form of rain. The rain should be out by the start of the day on Tuesday with the frontal passage. This leads temps to take on a non-diurnal curve on Tuesday as the warmest temps of the day should occur early on. As always is the case for this time of year, any changes to the thermal profile forecast could change precip types but for now, there appears to be general model consensus in the anticipated overall pattern for this time frame. Any snow that is able to stick to surfaces should be very light in accumulations. && .Aviation (00Z TAF Issuance)... Issued at 642 PM EST Tue Jan 29 2013 Deep upper-level trough over the Eastern Rockies will force a surface low pressure system now over the southern Plains to intensify and head quickly toward the Midwest this evening and overnight. The pressure gradient is beginning to tighten ahead of this low, with southerly winds starting to increase/gust. Latest wind profile guidance from CWSU ZSE indicates low-level wind shear is likely overnight, with 50-60 knots around 1900 feet AGL. So, will continue LLWS for all TAF sites. Convection currently across Illinois, Missouri, and Arkansas will form a more organized line of thunderstorms as the surface low strengthens tonight. This line will eventually move east through all TAF sites. Have put in the best thoughts for timing the actual line. Added VCTS a couple hours prior to account for any development ahead of the line. Some guidance indicates there could be two lines of convection. Will hit the TAFs harder when the line does approach. Expect MVFR cigs through most of the night, with conditions not improving until mid-late morning Wednesday. By late Wednesday afternoon, there could be low-topped showers/thunderstorms on the back side of this system, so will continue with VCSH through the end of the TAF period for now. && .Hydrology... Issued at 300 AM EST Tue Jan 29 2013 No real changes in the forecast thinking on the hydrologic front. An intense line of strong to severe thunderstorms is forecast to move across the region late tonight and early Wednesday morning. In addition to the threat of damaging winds, these storms will likely produce heavy rainfall. Once the system pulls east on Wednesday morning, a period of stratiform rainfall will likely persist for a few hours. Rainfall amounts averaging a little more than an inch in 6 hours should be widespread. Isolated amounts of up to 2 inches are possible. This rain could result in brief small stream flooding and later rises on larger rivers. Any flooding that will occur should be minor due to the fast nature of these storms. The rain will taper to scattered showers Wednesday afternoon. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...WIND ADVISORY UNTIL 4 PM EST /3 PM CST/ WEDNESDAY FOR INZ076>079- 083-084-089>092. KY...WIND ADVISORY UNTIL 4 PM EST /3 PM CST/ WEDNESDAY FOR KYZ023>032- 061-062-070>072. WIND ADVISORY UNTIL 7 PM EST /6 PM CST/ WEDNESDAY FOR KYZ033>043- 045>049-053>057-063>067-073>078-081-082. $$ Mesoscale........MJ/MJP Short Term.......RJS Long Term........lg Aviation.........RJP Hydrology........CMC
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
454 AM EST WED JAN 30 2013 .SYNOPSIS... LOW PRESSURE IS CENTERED OVER MICHIGAN. FROM THIS A WARM EXTENDS ACROSS PENNSYLVANIA WHILE A COLD FRONT EXTENDS FROM INDIANA TO ARKANSAS. THE COLD FRONT WILL MOVE THROUGH THE MID ATLANTIC STATES THIS EVENING. ANOTHER COLD FRONT WILL MOVE THROUGH THE REGION FRIDAY...FOLLOWED BY HIGH PRESSURE SATURDAY. && .NEAR TERM /TODAY/... AS OF 08Z...COLD FRONT IS OVER THE UPR MIDWEST WITH A PREFRONTAL BAND OF THUNDERSTORMS ASSOCIATED WITH A STRONG GULF PLUME EXTENDS FROM THE MS DELTA TO DETROIT. A WIDE SWATH OF TRAILING STRATIFORM IS OVER WRN IL AND IN. THIS COLD FRONT AND PREFRONTAL ACTIVITY WILL PROGRESS EAST THROUGH TODAY. THE 05Z HRRR DOES PLACE THE PREFRONTAL BAND AT THE ALLEGHENY FRONT BY 18Z...LESS THAN 10 HRS. THAT IS QUITE FAST...WITH 20Z SEEMINGLY A BETTER GUESS AS OF NOW. FLASH FLOOD WATCH IS IN EFFECT FOR COUNTIES ALONG THE ALLEGHENY FRONT AS WELL AS HAMPSHIRE/HARDY WHERE 6 HR FLASH FLOOD GUIDANCE IS AROUND AN INCH /1-2 INCHES ARE EXPECTED FOR THOSE COUNTIES/. ANY OTHER FLOODING LOOKS TO BE IN URBAN AREAS LIKE BALT-WASH. OTHERWISE A WELCOME HEAVY RAINFALL. SEVERE THREAT. VERY STRONG SHEAR AND VERY LOW CAPE WILL RESULT IN A DYNAMIC BAND. GUSTS AROUND 50 KT POSSIBLE WITH THIS BAND ACROSS THE LWX CWA. KEPT THUNDER CHANCES AT JUST CHANCE THOUGH THE MIDWEST HAS HAD A FAIR SHARE OF THUNDER TONIGHT. WIND. A STRONG LLJ AHEAD OF THIS FRONT WILL INCREASE OVERHEAD THROUGH THE DAY. A WIND ADVISORY IS IN EFFECT FOR MAJOR RIDGELINES BLUE RIDGE AND WEST FROM NOON THROUGH TONIGHT. WIND SHIFT TO WEST WITH FRONT WILL OCCUR SHORTLY AFTER MIDNIGHT. AS OF NOW WLY FLOW LOOKS TO BE BELOW 40 KT GUSTS...SO LATER SHIFTS WILL HAVE TO HONE IN ON IF THERE IS A WIND THREAT FOR LATE TONIGHT/THURSDAY MORNING. TEMPERATURES. WARM AHEAD OF THE COLD FRONT WITH UPR 50S OUT THERE NOW EASILY REACHING THE UPR 60S/LOW 70S BEFORE PREFRONTAL PRECIP/CLOUDS LIMIT INCREASES. 850MB TEMPS ARE NEAR 12C...SO MID 70S WOULD BE POSSIBLE IN SUNNY CONDITIONS. && .SHORT TERM /TONIGHT/... PRECIP SLOWLY CUTS OF WITH STRATIFORM TRAILING MAIN BAND FOR A FEW HOURS. UPSLOPE SNOW OF ONLY A COUPLE INCHES. NO WINTER ADVISORY EXPECTED. && .LONG TERM /THURSDAY THROUGH TUESDAY/... AFTR TUE AND TDA`S VERY WARM TEMPS THE RGN WL RETURN TO MORE NORMAL LATE JAN/ERLY FEB TEMPS FOR THE XTND PD. BRZY/WINDY WL BE THE OPERATIVE WORDS FOR THU AS HIGH PRES BUILDS INTO THE RGN. TEMPS THU WL BE 25 DEGS COOLER THAN TDA. UPSLOPE SNSH WL ALSO BE A CONCERN W/ SVRL INCHES OF ACCUM PSBL IN THE HIGHLANDS. AM ADVSRY MAY BE REQUIRED. HIGH PRES WL BUILD INTO THE RGN FRI AFTN AND SAT. HIGHS GNRLY IN THE U30S E OF THE MTNS. LOWS IN THE 20S. UPPER-LEVEL DISTURBANCES WILL BRING A CHANCE FOR SNOW SHOWERS...W/ THE BEST CHCS BEING ACROSS THE NORTHERN AND WESTERN CWA. DURG THE XTND PD FAST UPR LVL WL PREVAIL..AND W/ THIS IS THE PTNL FOR MORE ALBERTA CLIPPERS. A DISTURBANCE WILL PASS THROUGH SATURDAY NIGHT. ANOTHER MAY IMPACT THE AREA TUE. HIGHS CONT IN THE U30S/L40S SUN THRU TUE. LOWS IN THE MU20S. && .AVIATION /10Z WEDNESDAY THROUGH SUNDAY/... IFR STILL POSSIBLE THROUGH MID MORNING. SLY LOW LEVEL WIND SHEAR INCREASES TODAY PEAKING TONIGHT JUST AHEAD OF A COLD FRONT. CHANCES FOR THUNDER WITH VERY GUSTY WINDS...ON THE ORDER OF 50 KT. WINDS SHIFT WEST AND DECREASE LATE TONIGHT. GUSTY NW WINDS XPCTD THU. SKIES/CIGS SHOULD BE VFR. VFR CONDITIONS ARE EXPECTED MOST OF THE TIME THU NIGHT THROUGH SUNDAY. && .MARINE... SLY GALE EXPECTED BY LATE AFTERNOON CONTINUING UNTIL THE COLD FRONT CROSSES LATE TONIGHT. HIGH PRES BLDG INTO THE WATERS WL LKLY CONT TO CAUSE STRONG WIND GUSTS DURG THU. HV ISSUED A GALE WRNG FOR CHES BAY/LWR TIDAL PTMC...AND A STRONG SCA FOR THE RMDR OF THE WATERS. A COLD FRONT WILL PASS THROUGH THURSDAY NIGHT, GUSTY WINDS ARE EXPECTED BEHIND THE FRONT FRIDAY. HIGH PRES OVR THE WATERS SAT. ANOTHER COLD FRONT MAY IMPACT THE WATERS SUNDAY. && .TIDES/COASTAL FLOODING... A SOUTHERLY FLOW WILL INCREASE TODAY WITH GUSTS AROUND 35 KNOTS DURING THE AFTERNOON AND EVENING HOURS. THE STRONG SOUTHERLY FLOW WILL PUSH WATER UP THE MARYLAND PORTION OF THE CHESAPEAKE BAY AND THE TIDAL POTOMAC RIVER. DESPITE THE LOW ASTRONOMICAL NORMS...MODERATE FLOODING IS LIKELY NEAR TIMES OF HIGH TIDE WEDNESDAY AFTERNOON THROUGH WEDNESDAY NIGHT. A COASTAL FLOOD ADVSIROY HAS BEEN ISSUED FOR DC AND WRN SIDE OF CHES BAY FM ANNE ARUNDEL NWD. NW WINDS WILL ALLOW FOR TIDAL ANOMALIES TO DECREASE THU. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...COASTAL FLOOD ADVISORY FROM 7 PM THIS EVENING TO 3 AM EST THURSDAY FOR DCZ001. MD...WIND ADVISORY FROM NOON TODAY TO 6 AM EST THURSDAY FOR MDZ501. FLASH FLOOD WATCH FROM 3 PM EST THIS AFTERNOON THROUGH LATE TONIGHT FOR MDZ501-502. COASTAL FLOOD ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM EST THURSDAY FOR MDZ007-011-014. VA...WIND ADVISORY FROM NOON TODAY TO 6 AM EST THURSDAY FOR VAZ025>030-036>040-503-504. FLASH FLOOD WATCH FROM 3 PM EST THIS AFTERNOON THROUGH LATE TONIGHT FOR VAZ503-504. COASTAL FLOOD ADVISORY FROM 7 PM THIS EVENING TO 3 AM EST THURSDAY FOR VAZ054. WV...WIND ADVISORY FROM NOON TODAY TO 6 AM EST THURSDAY FOR WVZ050- 055-501>503-505-506. FLASH FLOOD WATCH FROM 3 PM EST THIS AFTERNOON THROUGH LATE TONIGHT FOR WVZ050-055-501>506. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR ANZ530>543. SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST THURSDAY FOR ANZ530>532-535-536-538>540. GALE WARNING FROM 4 PM THIS AFTERNOON TO 6 AM EST THURSDAY FOR ANZ530>532-535-536-538>540. GALE WARNING FROM 4 PM THIS AFTERNOON TO 6 PM EST THURSDAY FOR ANZ533-534-537-541>543. && $$ PRODUCTS...BAJ/WOODY!
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
409 AM EST WED JAN 30 2013 .SYNOPSIS... WELL ABOVE NORMAL TEMPERATURES...GUSTY WINDS AND RAIN SHOWERS TODAY AHEAD OF A STRONG COLD FRONT WHICH WILL PASS THROUGH LATE THIS AFTERNOON AND EVENING. MUCH COLDER AIR AND SNOW SHOWERS FOR THE REMAINDER OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WILL ISSUE A WIND ADVISORY TODAY FOR THE HIGHEST RIDGES IN GARRETT...PRESTON AND TUCKER COUNTIES. LATEST RUC FORECAST SOUNDINGS ON BUFKIT ARE SHOWING 60-65KTS TODAY JUST ABOVE 2500FT IN THESE COUNTIES. PER HPC DESIGNATION OF MOD RISK FOR EXCESSIVE RAINFALL AND COUNTIES WITH THE LOWEST FFG...WILL ISSUE FLOOD WATCH FOR PORTIONS OF THE SOUTH AND EAST TODAY AND TONIGHT. STRONG COLD FRONT WILL MOVE INTO W OHIO AFTER DAWN. SHOWERS AND SOME STORMS WILL ACCOMPANY THE FRONT AS IT CONTINUES ITS SLOW EASTWARD PROGRESSION. EXPECT A GOOD SOAKING TODAY WITH ONE- HALF TO ONE INCH OF RAIN FOR MUCH OF THE REGION. IN THE FLOOD WATCH COUNTIES...1 TO 2 INCHES OF RAIN IS POSSIBLE WITH THE BULK OF IT COMING THIS AFTERNOON AND EVENING. THE WATCH MAY NEED TO BE EXPANDED PARTICULARLY IF A LINE OF STRONG SLOW MOVING CONVECTION DEVELOPS. THE OTHER PROBLEM WILL BE THE POTENTIAL FOR STRONG WIND GUSTS ACROSS THE REST OF MY COUNTIES. LATEST CONVECTIVE OUTLOOK FOR TODAY PUT MUCH OF THE AREA IN A SLIGHT RISK. THINK THE BEST WAY TO HANDLE THIS IS TO INCLUDE THE POSSIBILITY OF SEVERE STORMS TODAY WITH DAMAGING WINDS. TEMPS WILL REMAIN WELL ABOVE NORMAL TODAY. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... MUCH COLDER AIR WILL RAPIDLY MOVE IN TONIGHT. LEFT OVER RAIN SHOWERS WILL CHANGE OVER TO SNOW SHOWERS AS THE NIGHT PROGRESSES. THINK THE BEST LOCATION FOR ANY ACCUMULATIONS WILL BE ACROSS THE HIGHER ELEVATIONS. IT DOES NOT APPEAR THAT THE SFC TEMPS WILL RESPOND QUICK ENOUGH ELSEWHERE TO ALLOW FOR ACCUMULATION. CONCERNED ABOUT DAMAGING WINDS BEHIND THE FRONT AS WELL. VERY STRONG CAA...COMBINED WITH PRES RISES OF 6 TO 8 MBS IS PRESENTING A PERIOD OVERNIGHT THAT MAY REQUIRE A WIND ADVISORY. WILL ALLOW THE NEXT SHIFT TO TAKE A CLOSER LOOK AT THIS. RISK FOR SNOW SHOWERS...MAINLY OVER THE FAR NORTH AND RIDGES...WILL CONTINUE THROUGH THE THURSDAY. TEMPERATURES WILL BE STEADY OR SLOWLY FALLING WITH GUSTY WINDS CONTINUING. AT THIS POINT...HAVE VERY LOW CONFIDENCE ON EFFECTS FROM SHORTWAVE WHICH WILL DIVE SOUTHWARD ACROSS THE REGION THU NIGHT. LATEST MODEL RUNS ARE HINTING AT SOME ACCUMULATING SNOWS...PARTICULARLY OVER THE SOUTHERN HALF. THU NIGHT/FRI MORN FORECAST WILL NEED FINE TUNING AS MODELS GET BETTER HANDLE ON LOCATION OF WAVE. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... UNCERTAINTY LIES IN THE FORECAST AS MODELS SEEM TO BE IN DISAGREEMENT. GFS/ECMWF DO SHOW A SHORTWAVE TROUGH MOVING OVER THE AREA ON THE WEEKEND AND THUS BRINGING A CLIPPER SOUTHEAST WITH THE GFS BRINGING HIGHER AMOUNTS OF SNOW THAN THE ECMWF. POSSIBLE LAKE ENHANCED AND/OR TERRAIN ENHANCED SNOW COULD DEVELOP AFTER THE PASSAGE OF THE QUICK MOVING SYSTEM. THE GFS BRINGS IN ANOTHER STRONGER CLIPPER OVER THE GREAT LAKES AND NORTHERN OHIO VALLEY MONDAY NIGHT INTO TUESDAY WHILE THE ECMWF TRACKS THE SYSTEM MORE NORTHEAST AND BRINGS PRECIPITATION TO OUR AREA ALONG A COLD FRONT. HIGH PRESSURE BUILDS BEHIND THE SYSTEM LEAVING THE MID WEEK DRY. HPC TRENDED TOWARDS THE ECMWF RUN THE LATTER PART OF THE EXTENDED AND THUS FORECAST IS BASED ON GFS/HPC GUIDANCE KEEPING SLIGHT TO CHANCE POPS. && .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/... VFR EXPD OVRNGT. LLVL JET SPEEDS WL BE INCRG OVRNGT AS WELL...WITH LLWS CONTG INTO WED MRNG. A STG CDFNT WL APRCH FM THE W WED... BRINGING MVFR SHRA AND GUSTY S WNDS. SOME INSTAB EVIDENT UPSTREAM TNGT LOOKING AT STLT/MESO/RAOB INSTAB CHART DATA. THIS SHOULD TRANSITION EWD WED WITH THE CDFNT. TS WL BE PSBL ALG/AHEAD OF THE CDFNT BUT LEFT OUT OF TAFS FOR NOW WITH RELATIVELY LOW PROB OF OCCURRANCE AT ANY ONE POINT. WL RE-EVALUATE FOR LTR TAFS. EXPT INITIAL WSHFT TO SW WITH PREFRONTAL TROF LT AFTN...THEN TO THE W WED EVE/NGT AS THE CDFNT MOVES THRU. WNDS WL BE GUSTY AS WELL BEHIND THE FNT. .OUTLOOK.../THURSDAY THROUGH SUNDAY/... PERIODIC RESTRICTION ARE EXPD THRU THE PD AS SVRL DISTURBANCES MOVE THRU IN COLD W-NW FLOW. GUSTY W WNDS ARE ALSO EXPTD THRU THU. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...FLOOD WATCH FROM 1 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR MDZ001. WIND ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MDZ001. OH...NONE. PA...FLOOD WATCH FROM 1 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR PAZ016-023-031-073>076. WV...FLOOD WATCH FROM 1 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR WVZ012-021>023-041. WIND ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR WVZ023-041. && $$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
400 AM EST WED JAN 30 2013 .SYNOPSIS... LOW PRESSURE IS CENTERED OVER MICHIGAN. FROM THIS A WARM EXTENDS ACROSS PENNSYLVANIA WHILE A COLD FRONT EXTENDS FROM INDIANA TO ARKANSAS. THE COLD FRONT WILL MOVE THROUGH THE MID ATLANTIC STATES THIS EVENING. ANOTHER COLD FRONT WILL MOVE THROUGH THE REGION FRIDAY...FOLLOWED BY HIGH PRESSURE SATURDAY. && .NEAR TERM /TODAY/... AS OF 08Z...COLD FRONT IS OVER THE UPR MIDWEST WITH A PREFRONTAL BAND OF THUNDERSTORMS ASSOCIATED WITH A STRONG GULF PLUME EXTENDS FROM THE MS DELTA TO DETROIT. A WIDE SWATH OF TRAILING STRATIFORM IS OVER WRN IL AND IN. THIS COLD FRONT AND PREFRONTAL ACTIVITY WILL PROGRESS EAST THROUGH TODAY. THE 05Z HRRR DOES PLACE THE PREFRONTAL BAND AT THE ALLEGHENY FRONT BY 18Z...LESS THAN 10 HRS. THAT IS QUITE FAST...WITH 20Z SEEMINGLY A BETTER GUESS AS OF NOW. FLASH FLOOD WATCH IS IN EFFECT FOR COUNTIES ALONG THE ALLEGHENY FRONT AS WELL AS HAMPSHIRE/HARDY WHERE 6 HR FLASH FLOOD GUIDANCE IS AROUND AN INCH /1-2 INCHES ARE EXPECTED FOR THOSE COUNTIES/. ANY OTHER FLOODING LOOKS TO BE IN URBAN AREAS LIKE BALT-WASH. OTHERWISE A WELCOME HEAVY RAINFALL. SEVERE THREAT. VERY STRONG SHEAR AND VERY LOW CAPE WILL RESULT IN A DYNAMIC BAND. GUSTS AROUND 50 KT POSSIBLE WITH THIS BAND ACROSS THE LWX CWA. KEPT THUNDER CHANCES AT JUST CHANCE THOUGH THE MIDWEST HAS HAD A FAIR SHARE OF THUNDER TONIGHT. WIND. A STRONG LLJ AHEAD OF THIS FRONT WILL INCREASE OVERHEAD THROUGH THE DAY. A WIND ADVISORY IS IN EFFECT FOR MAJOR RIDGELINES BLUE RIDGE AND WEST FROM NOON THROUGH TONIGHT. WIND SHIFT TO WEST WITH FRONT WILL OCCUR SHORTLY AFTER MIDNIGHT. AS OF NOW WLY FLOW LOOKS TO BE BELOW 40 KT GUSTS...SO LATER SHIFTS WILL HAVE TO HONE IN ON IF THERE IS A WIND THREAT FOR LATE TONIGHT/THURSDAY MORNING. TEMPERATURES. WARM AHEAD OF THE COLD FRONT WITH UPR 50S OUT THERE NOW EASILY REACHING THE UPR 60S/LOW 70S BEFORE PREFRONTAL PRECIP/CLOUDS LIMIT INCREASES. 850MB TEMPS ARE NEAR 12C...SO MID 70S WOULD BE POSSIBLE IN SUNNY CONDITIONS. && .SHORT TERM /TONIGHT/... PRECIP SLOWLY CUTS OF WITH STRATIFORM TRAILING MAIN BAND FOR A FEW HOURS. UPSLOPE SNOW OF ONLY A COUPLE INCHES. NO WINTER ADVISORY EXPECTED. && .LONG TERM /THURSDAY THROUGH TUESDAY/... AFTR TUE AND TDA`S VERY WARM TEMPS THE RGN WL RETURN TO MORE NORMAL LATE JAN/ERLY FEB TEMPS FOR THE XTND PD. BRZY/WINDY WL BE THE OPERATIVE WORDS FOR THU AS HIGH PRES BUILDS INTO THE RGN. TEMPS THU WL BE 25 DEGS COOLER THAN TDA. UPSLOPE SNSH WL ALSO BE A CONCERN W/ SVRL INCHES OF ACCUM PSBL IN THE HIGHLANDS. AM ADVSRY MAY BE REQUIRED. HIGH PRES WL BUILD INTO THE RGN FRI AFTN AND SAT. HIGHS GNRLY IN THE U30S E OF THE MTNS. LOWS IN THE 20S. UPPER-LEVEL DISTURBANCES WILL BRING A CHANCE FOR SNOW SHOWERS...W/ THE BEST CHCS BEING ACROSS THE NORTHERN AND WESTERN CWA. DURG THE XTND PD FAST UPR LVL WL PREVAIL..AND W/ THIS IS THE PTNL FOR MORE ALBERTA CLIPPERS. A DISTURBANCE WILL PASS THROUGH SATURDAY NIGHT. ANOTHER MAY IMPACT THE AREA TUE. HIGHS CONT IN THE U30S/L40S SUN THRU TUE. LOWS IN THE MU20S. && .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/... IFR STILL POSSIBLE THROUGH MID MORNING. SLY LOW LEVEL WIND SHEAR INCREASES TODAY PEAKING TONIGHT JUST AHEAD OF A COLD FRONT. CHANCES FOR THUNDER WITH VERY GUSTY WINDS...ON THE ORDER OF 50 KT. WINDS SHIFT WEST AND DECREASE LATE TONIGHT. GUSTY NW WINDS XPCTD THU. SKIES/CIGS SHOULD BE VFR. VFR CONDITIONS ARE EXPECTED MOST OF THE TIME THU NIGHT THROUGH SUNDAY. && .MARINE... SLY GALE EXPECTED BY LATE AFTERNOON CONTINUING UNTIL THE COLD FRONT CROSSES LATE TONIGHT. HIGH PRES BLDG INTO THE WATERS WL LKLY CONT TO CAUSE STRONG WIND GUSTS DURG THU. HV ISSUED A GALE WRNG FOR CHES BAY/LWR TIDAL PTMC...AND A STRONG SCA FOR THE RMDR OF THE WATERS. A COLD FRONT WILL PASS THROUGH THURSDAY NIGHT, GUSTY WINDS ARE EXPECTED BEHIND THE FRONT FRIDAY. HIGH PRES OVR THE WATERS SAT. ANOTHER COLD FRONT MAY IMPACT THE WATERS SUNDAY. && .TIDES/COASTAL FLOODING... A SOUTHERLY FLOW WILL INCREASE TODAY WITH GUSTS AROUND 35 KNOTS DURING THE AFTERNOON AND EVENING HOURS. THE STRONG SOUTHERLY FLOW WILL PUSH WATER UP THE MARYLAND PORTION OF THE CHESAPEAKE BAY AND THE TIDAL POTOMAC RIVER. DESPITE THE LOW ASTRONOMICAL NORMS...MODERATE FLOODING IS LIKELY NEAR TIMES OF HIGH TIDE WEDNESDAY AFTERNOON THROUGH WEDNESDAY NIGHT. A COASTAL FLOOD HEADLINE DECISION WILL BE MADE SHORTLY. NW WINDS WILL ALLOW FOR TIDAL ANOMALIES TO DECREASE THU. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...COASTAL FLOOD WATCH FROM 2 PM EST THIS AFTERNOON THROUGH LATE TONIGHT FOR DCZ001. MD...WIND ADVISORY FROM NOON TODAY TO 6 AM EST THURSDAY FOR MDZ501. FLASH FLOOD WATCH FROM 3 PM EST THIS AFTERNOON THROUGH LATE TONIGHT FOR MDZ501-502. COASTAL FLOOD WATCH FROM 2 PM EST THIS AFTERNOON THROUGH LATE TONIGHT FOR MDZ007-011-013-014-016>018. VA...WIND ADVISORY FROM NOON TODAY TO 6 AM EST THURSDAY FOR VAZ025>030-036>040-503-504. FLASH FLOOD WATCH FROM 3 PM EST THIS AFTERNOON THROUGH LATE TONIGHT FOR VAZ503-504. COASTAL FLOOD WATCH FROM 2 PM EST THIS AFTERNOON THROUGH LATE TONIGHT FOR VAZ052>055-057. WV...WIND ADVISORY FROM NOON TODAY TO 6 AM EST THURSDAY FOR WVZ050- 055-501>503-505-506. FLASH FLOOD WATCH FROM 3 PM EST THIS AFTERNOON THROUGH LATE TONIGHT FOR WVZ050-055-501>506. MARINE...SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 4 PM EST THIS AFTERNOON FOR ANZ530>543. SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST THURSDAY FOR ANZ530>532-535-536-538>540. GALE WARNING FROM 4 PM THIS AFTERNOON TO 6 AM EST THURSDAY FOR ANZ530>532-535-536-538>540. GALE WARNING FROM 4 PM THIS AFTERNOON TO 6 PM EST THURSDAY FOR ANZ533-534-537-541>543. && $$ PRODUCTS...BAJ/WOODY!
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1232 AM EST WED JAN 30 2013 .SYNOPSIS... ISSUED AT 348 PM EST TUE JAN 29 2013 AREAS OF FOG WILL GIVE WAY TO HEAVY RAIN TONIGHT AS LOW PRESSURE MOVES THROUGH. SOME FLOODING IS POSSIBLE. THE RAIN WILL MOVE EAST ON WEDNESDAY WITH COLDER AIR MOVING IN ALONG WITH SOME RAIN CHANGING TO SNOW. TEMPERATURES WILL CONTINUE TO FALL THROUGH FRIDAY ALONG WITH LAKE EFFECT SNOW SHOWERS. && .UPDATE... ISSUED AT 817 PM EST TUE JAN 29 2013 AT 0105Z THE KGRR 88D SHOWS RAIN AND ISOLATED THUNDERSTORMS. NO SEVERE WX IS ANTICIPATED IN OUR AREA TONIGHT. LATEST HIGHER RESOLUTION GUIDANCE SUCH AS THE 12Z 4KM WRF NMM INDICATES WE WILL HAVE RAIN AND SCATTERED THUNDERSTORMS THROUGH THE OVERNIGHT PERIOD. RAIN COULD BE HEAVY AT TIMES. THEREFORE NO HEADLINE CHANGES ARE PLANNED/NECESSARY THIS EVENING AND THE FLOOD WATCH CONTINUES IN EFFECT THROUGH WEDNESDAY AFTERNOON. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 348 PM EST TUE JAN 29 2013 AREAS OF PATCHY DENSE FOG WILL CONTINUE THIS EVENING ACROSS THE NORTHERN ZONES UNTIL THE WARM FRONT LIFTS THROUGH. COVERAGE IS VARIABLE ENOUGH TO NOT GO WITH A DENSE FOG ADVISORY BUT WILL HAVE TO MONITOR OBS NEXT FEW HOURS. FLOOD WATCH CONTINUES TONIGHT FOR ALL ZONES. MOST IF NOT ALL OF THE SNOW IS GONE ACROSS THE CENTRAL AND SOUTHERN ZONES BUT SOME SNOWMELT CONTRIBUTION REMAINS UP NORTH WHERE QPF IS EXPECTED TO BE 1 TO 2 INCHES. 12Z MODEL GUIDANCE SHIFTED NORTH WITH THE AXIS OF HEAVIEST QPF ALTHOUGH THE HRRR HAS BEEN SHOWING THE MOST CONVECTIVE...AND HEAVIER...RAINS FURTHER SOUTH AND EAST. SEE HYDRO SECTION OF FORECAST FOR SPECIFICS ON RIVER FLOOD WARNINGS. EXPECT THE HEAVIEST RAINS TO MOVE INTO WESTERN ZONES THIS EVENING THEN MARCH STEADILY ACROSS THE FORECAST AREA OVERNIGHT...DEPARTING THE EASTERN ZONES WEDNESDAY MORNING. THE DEFORMATION RAIN/SNOW ZONE SHOULD BE REACHING THE NORTHWEST FORECAST AREA WEDNESDAY MORNING. WILL HAVE TO WATCH THIS AREA FOR ACCUMULATING SNOW BY LATE WEDNESDAY MORNING INTO THE AFTERNOON. COLD AIR ARRIVES IN THE AFTERNOON WITH LAKE EFFECT KICKING IN WEDNESDAY NIGHT. EXPECT LAKE EFFECT TO PENETRATE INLAND THURSDAY AND THURSDAY NIGHT WITH FLOW GOING NORTHWEST TO WEST. .LONG TERM...(FRIDAY THROUGH TUESDAY) ISSUED AT 348 PM EST TUE JAN 29 2013 THE ECMWF AND GFS ARE IN PRETTY GOOD AGREEMENT THROUGH THE WEEKEND. BOTH MODELS SHOW THE DEEP UPPER TROUGH MOVING EAST AWAY FROM THE AREA AND TAKING THE CORE OF THE COLD AIR WITH IT. THE DGZ IS ALREADY GOING TO BE VERY LOW FRIDAY AND WITH THE COLD AIR MOVING AWAY WE/LL SEE THE EASTERN EDGE OF THE LAKE EFFECT SNOW SHOWERS RETREATING TOWARD THE LAKE SHORE AND THEN DIMINISHING FRIDAY NIGHT AND SATURDAY. THE NEXT CHC FOR SNOW AFTER THAT WILL BE MONDAY WHEN A CLIPPER MOVES TOWARD NRN LWR. THE GFS TAKES A MORE SRN TRACK AND WOULD GIVE US MORE SNOW. HOWEVER...WE HAVE NOT HAD MANY CLIPPERS THAT HAVE CROSSED THE CWA THIS YEAR AND SO WE/LL LEAN MORE TOWARD THE FARTHER NORTH ECMWF. TEMPS WILL WARM FROM HIGHS IN THE MID TEENS FRIDAY TO MID 30S BY MONDAY BEFORE COOLING OFF TUESDAY AFTER THE CLIPPER DRAGS A COLD FRONT THROUGH. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1228 AM EST WED JAN 30 2013 VERY COMPLEX AVIATION FORECAST THE NEXT 24 HOURS...AS A LOW PRESSURE CENTER MOVES THROUGH THE AREA. CHANGEABLE AVIATION CATEGORIES AND WIND DIRECTION WILL MAKE FOR A COMPLICATED FORECAST. IN GENERAL...AVIATION CONDITIONS WILL DIP OVERNIGHT BACK INTO IFR AT MOST SITES AS THE WINDS SLACK OFF A BIT WITH THE LOW AND HEAVIER RAIN MOVES BACK IN. A GRADUAL IMPROVEMENT SHOULD BE SEEN ON WEDNESDAY...BUT WE SHOULD NOT IMPROVE BEYOND MVFR THROUGH THE DAY. RAIN WILL BEGIN TO CHANGE TO SNOW FROM WEST TO EAST DURING THE EVENING HOURS. && .MARINE... ISSUED AT 348 PM EST TUE JAN 29 2013 WILL HOIST A SMALL CRAFT ADVISORY FOR TONIGHT THROUGH THURSDAY MORNING. THIS MAY HAVE TO BE UPGRADED TO A GALE WARNING FOR WEDNESDAY LATER ON...BUT FOR NOW IT APPEARED MARGINAL ENOUGH TO JUST GO WITH A SCA THROUGH THE PERIOD. && .HYDROLOGY... ISSUED AT 957 PM EST TUE JAN 29 2013 HAVE ISSUED A FLOOD WARNING FOR THE LAKESHORE COUNTIES AS WELL AS LAKE AND NEWAYGO COUNTY. AREAS THAT RECEIVED SUBSTANTIAL LAKE EFFECT SNOW IN THE LAST WEEK OR SO HAVE SEEN A RAPID SNOW MELT THAT HAS OCCURRED OVER FROZEN GROUND. THEREFORE...SNOW MELT WATER AND RAINFALL IS GOING INTO RUNOFF AS OPPOSED TO INFILTRATING INTO THE GROUND. RAINFALL TOTALS HAVE BEEN IMPRESSIVE SINCE LAST NIGHT...WITH MUSKEGON SEEING OVER 2.25 INCHES OF RAIN NOW. THE COMBINATION SNOW MELT WATER...RAINFALL OF THE LAST 24 HOURS AND ADDITIONAL RAINFALL COMING UP TONIGHT HAS PROMPTED THE AREAL FLOOD WARNING. DROPPED THE FLOOD WATCH IN THESE COUNTIES GIVEN THE WARNING. THE FLOOD WATCH CONTINUES FOR THE REMAINDER OF THE AREA. THE EXPECTATIONS IN THE WARNING AREA ARE THAT WE WILL SEE SMALLER STREAMS AND RIVERS SPILL OUR OF THERE BANKS...PONDING OF WATER IN LOW SPOTS OF ROADWAYS AND FLOODING OF CULVERTS...DITCHES AND FIELDS. A SATELLITE PRECIPITATION ESTIMATE (SPENES) WAS RECENTLY ISSUED ADVISING OF THE POTENTIAL OF ANOTHER 1-2 INCHES OF RAINFALL ACROSS OUR AREA THROUGH 400 AM. WE WILL BE MONITORING THE COUNTIES TO THE EAST OF THE WARNING AREA...BUT CONCERNS ARE NOT AS HIGH THERE AS THE SNOW PACK WAS MINIMAL. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...FLOOD WATCH THROUGH THIS AFTERNOON FOR MIZ039-040-045-046-051- 052-057>059-065>067-072>074. LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST THURSDAY FOR LMZ844>849. && $$ UPDATE...LAURENS SYNOPSIS...OSTUNO SHORT TERM...OSTUNO LONG TERM...93 AVIATION...DUKE HYDROLOGY...DUKE MARINE...OSTUNO
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1205 AM EST WED JAN 30 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 504 PM EST TUE JAN 29 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM NE MANITOBA THROUGH THE PLAINS INTO NEW MEXICO. WEAK SHRTWVS EMBEDDED IN THE SW FLOW FROM THE SRN PLAINS INTO THE GREAT LAKES SUPPORTED AREAS OF SHRA/TSRA NEAR A SFC FRONT EXTENDING FROM NE WI THROUGH CNTRL MO AND INTO CNTRL OK. THE MAIN SHRTWV WAS REMAINED NEAR THE BASE OF THE TROUGH...MOVING TOWARD THE TX/OK PANHANDLE. PCPN HAD DIMINISHED OVER UPPER MICHIGAN WITH MAINLY SOME SCT LIGHT SHOWERS MOVING THROUGH FAR SRN UPPER MI. WEST WINDS AND SLIGHTLY DRIER AIR BEHIND A TROUGH SLIDING TO NEAR P53-ISQ HAS BROUGHT IMPROVED VISIBILITIES THROUGH THE CNTRL AND WEST CWA. ALTHOUGH THE 12Z ECMWF WAS A BIT SLOWER THAN THE 12Z GFS...THE MODELS WERE IN RELATIVELY GOOD AGREEMENT WITH REGARD TO OVERALL PCPN/SNOW POTENTIAL ACROSS THE CWA. ALTHOUGH THE 12Z NAM HAD SHIFTED THE HEAVIER QPF AXIS WELL TO THE EAST...THE 18Z RUN HAS COME BACK INTO BETTER AGREEMENT WITH THE GLOBAL MODELS. MODELS DIFFICULTY IN HANDLING THE CONVECTION AND HEAVY RAIN NEAR THE FRONT MAY ACCOUNT FOR A PORTION OF THE INCONSISTENCY AND VARIABILITY AND STILL LEADS GREATER THAN USUAL UNCERTAINTY. ALTHOUGH THERE IS MODERATE CONFIDENCE WITH THE MULTI-MODEL BLEND OF THE GFS/ECMWF/NAM/REG-GEM USED FOR QPF...TIMING OF THE HEAVIER PCPN ONSET MAY BE A BIT DELAYED GIVEN ECMWF/NAM TRENDS. THE STRONGEST DYNAMICS ARE EXPECTED TO DEVELOP BTWN 12Z-18Z/WED AS THE NM SHRTWV LIFTS TOWARD THE GREAT LAKES. A COUPLED UPPER LEVEL JET STRUCTURE AND RESULTING STRONG 800-600 MB FGEN WILL SUPPORT A PERIOD OF MODERATE TO HEAVY PCPN IN THE REGION...WITH THE BEST CHANCE FOR HEAVY SNOW OVER THE SE HALF OF UPPER MI. EXPECT A SHARP NW EDGE OF THE PCPN BAND DUE TO STRONG DESCENDING FGEN CIRCULATION BRANCH WHICH REDUCES CONFIDENCE IN PCPN AMOUNTS THROUGH CNTRL UPPER MI. QPF VALUES IN THE 0.30 TO 0.60 INCH RANGE WITH SNOW/WATER RATIO VALUES NEAR 16/1 SUPPORTS GENERALLY 4 TO 8 INCH SYNOPTIC SNOW...GREATEST OVER THE FAR S AND EAST. LAKE ENHANCED SNOW WILL GENERALLY BE LIGHT EARLY WED WITH LOW INVERSION HEIGHTS NEAR 4K FT AND 850 MB TEMPS ONLY NEAR -10C BUT BY WED AFTERNOON SNOWFALL RATES OVER N CNTRL AND FAR WEST NEAR IWD SHOULD INCREASE AS 850 MB TEMPS FALL TO NEAR -16C. ALTHOUGH UPSLOPE FLOW SHOULD ENHANCE SNOWFALL RATES...CYCLONIC 350 FLOW MAY ALSO LEAD TO GREATER AMOUNTS NEAR THE SHORE WED AFTERNOON. FCST CONFIDENCE WAS HIGH ENOUGH TO UPGRADE WATCHES TO WARNINGS OVER THE EAST HALF BUT WITH AMOUNTS ONLY IN THE 2 TO 5 INCH RANGE OVER MARQUETTE AND DICKINSON COUNTIES THROUGH WED AND PROXIMITY TO THE EDGE OF THE SYNOPTIC PCPN...AN ADVY WAS ISSUED. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 446 PM EST TUE JAN 29 2013 INITIAL PART OF THE LONG TERM FORECAST IS HIGHLY DEPENDENT ON THE TRACK OF THE SHORTWAVE RIDING UP THE UPPER TROUGH OVER THE CENTRAL CONUS AND THE ASSOCIATED LOW DEVELOPING IN NORTHERN LOWER MI AND THEN SHIFTING NORTHEAST INTO QUEBEC ON WEDNESDAY NIGHT. THE SHORT TERM DISCUSSION COVERS MUCH OF THE DETAILS WITH THIS SYSTEM AND THE MAIN FEATURE TO CAPTURE IN THE LONG TERM WITH THIS SYSTEM IS THE DIMINISHING TREND IN THE POPS/QPF OVER THE EASTERN CWA. BEHIND THIS FEATURE...EXPECT COLD AIR TO SURGE SOUTHEAST OVER THE UPPER GREAT LAKES REGION AND REMAIN INTO THE WEEKEND. THIS COLD AIR...H850 TEMPS IN THE LOW -20S CELSIUS...MOVING ACROSS THE RELATIVELY WARM LAKE SUPERIOR WATERS WILL LEAD TO PERSISTENT LAKE EFFECT. AMOUNTS AND LOCATIONS WILL LARGELY DEPEND ON WIND DIRECTION AND DEEPER MOISTURE DURING THIS PERIOD. FOR WEDNESDAY NIGHT...LAKE EFFECT WILL BE INCREASING IN INTENSITY OVER THE WEST THROUGH THE NIGHT DUE TO INCREASING COLD AIR AND DEEPER MOISTURE ARRIVING FROM THE NORTHWEST. THIS WILL PUSH INVERSION HEIGHTS TOWARDS 10KFT OVER THE WITH WESTERN AREAS AND WITH DELTA-T VALUES AROUND 23...LAKE INDUCED CAPE VALUES RISE TOWARDS 500-700 J/KG. EXPECT THE HIGHEST AMOUNTS...2-6 INCHES...IN THE NORTH-NORTHWEST WIND FAVORED LOCATIONS. OVER THE EAST...FORECAST IS A LITTLE MORE UNCERTAIN DUE TO THE SYSTEM...BUT THEY TOO SHOULD TRANSITION TO LAKE EFFECT. WITH MOISTURE HELP FROM THE SYSTEM...SNOW AMOUNTS WILL BE HIGHER THERE ESPECIALLY IN THE LOCATIONS FAVORED BY NORTH-NORTHWEST WINDS. THE HIGHEST AMOUNTS WILL LIKELY OCCUR THROUGH THE NIGHT OVER THE WESTERN PORTIONS OF ALGER COUNTY...WHERE COASTAL EFFECTS FROM NORTHERN MARQUETTE COUNTY WILL LIKELY INCREASE CONVERGENCE THERE AND THUS SNOWFALL AMOUNTS. HAVE TRENDED POPS TOWARDS THIS IDEA FOR THE WEDNESDAY NIGHT PERIOD. WITH THE COLD AIR CONTINING TO FLOW OVER THE AREA ON THURSDAY...MULTI-BAND LAKE EFFECT WILL BE AIDED BY THE INCREASED MID LEVEL MOISTURE MOVING OVER THE AREA BEHIND A SHORTWAVE DROPPING THROUGH THE UPPER/MID MISSISSIPPI VALLEY ON THURSDAY. THIS WILL LEAD TO INVERSION HEIGHTS IN THE 7-10KFT RANGE OVER THE AREA...WITH THE HIGHEST VALUES OVER THE EAST. THE MAIN DETERMINING FACTOR FOR SNOW AMOUNTS IN THE NORTHWEST WIND FAVORED LOCATIONS ON THURSDAY WILL BE WHEN THE DGZ FALLS BELOW OR TO THE BOTTOM OF THE CLOUD LAYER. THIS WILL OCCUR FIRST OVER THE WEST AND THEN OVER THE EAST LATE IN THE DAY. THIS WILL LEAD TO A TRANSITION TO LOWER SNOW RATIOS WITH THE TRANSITION TO MORE COLUMNS THAT IS USUALLY SEEN IN COLD/ARCTIC AIR MASSES. WITH THE WINDS BACKING TO MORE OF A NORTHWEST WIND DIRECTION THROUGH DAY...WOULD EXPECT THERE TO BE A COUPLE ENHANCED LOCATIONS DUE TO INCREASED CONVERGENCE. AT THIS TIME...WOULD EXPECT IT TO BE OVER GOGEBIC/ONTONAGON AND ALGER COUNTIES. HIGH PRESSURE SLIDING SOUTHEAST FROM THE DAKOTAS ON THURSDAY NIGHT WILL LEAD TO BACKING WINDS TO THE WEST OVER THE WESTERN LAKE AND WEST-NORTHWEST OVER THE EAST. THIS WILL CONTINUE INTO FRIDAY AS THE HIGH MOVES INTO THE MID MISSISSIPPI VALLEY AND LEADS TO WEST TO WEST-SOUTHWEST WINDS. THESE WINDS WILL BE AIDED BY A WEAK LOW DEVELOPING OVER EASTERN LAKE SUPERIOR. COLD AIR IS STILL IN THE LOWER -20S CELSIUS DURING THE PERIOD...SO THE LAKE EFFECT WILL BE ONGOING. BUT...WITH THE HIGH REDUCING THE MOISTURE ABOVE H850 AND INCREASING THE SUBSIDENCE INVERSION EXPECT THERE TO BE A GRADUAL DECREASE IN INTENSITY DURING THAT TIME FRAME. DEFINITELY THINK THAT THE NORTH-NORTHWEST WIND LOCATIONS WILL NEED LAKE EFFECT SNOW ADVISORIES DURING THIS WEDNESDAY NIGHT INTO THURSDAY NIGHT PERIOD. WARNINGS ARE A LITTLE MORE UNCERTAIN DUE TO THE LIMITED PERIODS OF THE BEST OMEGA WITHIN THE DGZ. OUT OF ALL OF THE LOCATIONS...WOULD THINK THAT ALGER COUNTY WOULD HAVE THE BEST OPPORTUNITY OF SEEING WARNING SNOWFALL AMOUNTS. OPTED TO GO AHEAD AND ISSUE THE LAKE EFFECT SNOW ADVISORY FOR GOGEBIC/ONTONAGON COUNTIES AND THE REST OF THE FAVORED AREAS WILL NEEDED TO BE ADDED IN THE NEXT 12-24HRS. HEADING INTO THE WEEKEND...THE COLDER AIR WILL BEGIN TO LOSE IT/S GRIP ON THE AREA AS THE UPPER TROUGH SHIFTS TO THE EAST AND AREA COMES UNDER NORTHWEST FLOW ALOFT. THESE PERIODS COME DOWN TO TIMING/LOCATING SHORTWAVES MOVING THROUGH THE FLOW AND HAVE TRIED TO FOLLOW A GENERAL CONSENSUS FOR TIMING THESE WAVES. FIRST ONE LOOKS TO MOVE THROUGH THE AREA ON SATURDAY NIGHT AND AGAIN ON SUNDAY NIGHT INTO MONDAY. BETWEEN THOSE TWO PERIODS...THERE SHOULD BE ENOUGH COLD AIR TO SUPPORT LAKE EFFECT SNOW IN AREAS FAVORED BY NORTHWEST WINDS. WITH THE COLD AIR SPILLING INTO THE AREA...A COOLING TREND IS EXPECTED FOR THE SECOND HALF OF THE WORK WEEK. FRIDAY CONTINUES TO LOOK LIKE THE COLDEST DAY OVER THE NEXT 7 DAYS...WITH HIGHS OVER THE WEST STRUGGLING TO RISE ABOVE 0 DEGREES. THIS COLD AIR WILL CAUSE WIND CHILL VALUES TO APPROACH -25 ON ON THURSDAY NIGHT INTO FRIDAY MORNING AND AGAIN FRIDAY NIGHT INTO SATURDAY MORNING OVER THE INTERIOR WEST HALF OF UPPER MICHIGAN. TEMPERATURES WILL THEN WARM BACK TO MORE NORMAL VALUES BY THE FIRST PART OF NEXT WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1205 AM EST WED JAN 30 2013 CONFIDENCE IN THIS FORECAST CONTINUES TO BE LOW AS DRIER AIR SEEMS TO BE WINNING OVER UPSLOPE LOW CIGS THAT WERE EXPECTED TO REMAIN AND DEVELOP OVERNIGHT. MVFR CONDITIONS WILL CONTINUE AT CMX THROUGH THE PERIOD. AT IWD...LAKE ENHANCEMENT KICKS IN WITH VISIBILITY FALLING TO IFR BY WED MORNING AND STAYING THERE THROUGH THE REST OF THE PERIOD WITH UPSLOPE HELPING THE LAKE EFFECT. MVFR CONDITIONS AT SAW WILL GIVE WAY TO IFR BY WED MORNING AS SYSTEM SNOW MOVES IN. AS WINDS GO NNW BY EVENING...CONDITIONS SHOULD IMPROVE TO MVFR AT SAW AS SYSTEM SNOW MOVES OUT. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 504 PM EST TUE JAN 29 2013 A DEEPENING LOW PRESSURE SYSTEM MOVING THROUGH LAKE HURON WEDNESDAY AND TO THE NORTHEAST BY WEDNESDAY NIGHT WILL LIKELY BRING A PERIOD OF N TO NW GALES TO CENTRAL AND EASTERN LAKE SUPERIOR LATE TONIGHT INTO WEDNESDAY NIGHT. WINDS/WAVES COMBINED WITH ARCTIC AIR SETTLING OVER THE AREA WILL RESULT IN FREEZING SPRAY...POSSIBLY HEAVY AT TIMES LATE WEDNESDAY INTO FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 3 AM TO 9 PM CST WEDNESDAY FOR MIZ011. WINTER STORM WARNING UNTIL 10 PM EST /9 PM CST/ THIS EVENING FOR MIZ012>014. WINTER STORM WARNING FROM 4 AM EARLY THIS MORNING TO 7 AM EST THURSDAY FOR MIZ006-007-085. LAKE EFFECT SNOW ADVISORY FROM 7 AM EST /6 AM CST/ THIS MORNING TO 7 AM EST /6 AM CST/ FRIDAY FOR MIZ002-009. WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 1 AM EST THURSDAY FOR MIZ005. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING FROM 7 PM THIS EVENING TO 7 AM EST FRIDAY FOR LSZ265>267. GALE WARNING FROM 10 AM THIS MORNING TO 4 AM EST THURSDAY FOR LSZ267. GALE WARNING FROM 5 AM EARLY THIS MORNING TO 4 AM EST THURSDAY FOR LSZ264>266. HEAVY FREEZING SPRAY WARNING FROM 1 PM EST /NOON CST/ THIS AFTERNOON TO 7 AM EST /6 AM CST/ FRIDAY FOR LSZ162-263-264. GALE WARNING FROM 5 AM EARLY THIS MORNING TO 10 PM EST THIS EVENING FOR LSZ263. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...SRF AVIATION...07 MARINE...JLB
AREA FORECAST DISCUSSION
NWS BILLINGS MT
842 PM MST TUE JAN 29 2013 .SHORT TERM...VALID FOR WED AND THU... INFRARED SATELLITE IMAGES HAVE SHOWN SIGNIFICANT CLOUD-TOP WARMING WITH THE CONVECTIVE ELEMENTS ACROSS SOUTHEASTERN MT SINCE ABOUT 22 UTC...AND OBSERVATIONS FROM MILES CITY AND BAKER HAVE BEEN SHOWING AN UPTICK IN VISIBILITY THE LAST FEW HOURS TOO. WE ARE COMFORTABLE DROPPING THE WINTER WEATHER ADVISORY FOR CUSTER COUNTY A FEW HOURS EARLY AS LOW- AND MID-LEVEL STABILIZATION IS SHUTTING DOWN MOST OF THE SNOW SHOWER ACTIVITY IN THAT AREA. PLUS...THE CORE OF PRESSURE RISES THAT WAS RESPONSIBLE FOR GUSTY WINDS IS EXITING INTO WESTERN SD AS OF 03 UTC. WIND CHILLS ARE DOWN INTO THE -20 F RANGE ALREADY THOUGH...AND THERE SHOULD BE ENOUGH SURFACE GRADIENT TO KEEP WINDS CLOSE TO 10 MPH THROUGH AT LEAST 09 UTC...SO WE WILL KEEP THE WIND CHILL ADVISORY FOR PART OF SOUTHEASTERN MT IN EFFECT. MEANWHILE... WE DECIDED TO END THE WIND CHILL ADVISORY A FEW HOURS EARLY IN THE JUDITH GAP AREA...WHERE WINDS HAVE DIMINISHED AND TEMPERATURES ARE ACTUALLY RISING A BIT WITH AN INCREASE IN CLOUDS. THE FORECAST WAS ALSO UPDATED TO REDUCE POPS IN SOME SPOTS FOR THE NIGHTTIME HOURS OUT OF RESPECT TO THE 18 UTC MULTI-MODEL CONSENSUS AND THE 00 UTC NAM AND RAP SOLUTIONS...ALL OF WHICH SUGGEST LITTLE IN THE WAY OF QPF IN MOST AREAS THROUGH 12 UTC. HOWEVER...THE NEXT WAVE OF SNOW WILL BE DRIVEN BY WARM AIR ADVECTION ALOFT IDENTIFIED BY FORCING ON ISENTROPIC SURFACES...AND SUBJECTIVE OBSERVATIONS DO SUGGEST THAT MODELS ARE OFTEN TOO SLOW TO GENERATE QPF WITH EVENTS LIKE THIS ONE. THUS...WE NEEDED TO KEEP SOME 20 TO 30 PERCENT POPS FOR MOST LOWER ELEVATIONS AFTER 06 UTC. FINALLY...SURFACE PRESSURE FALLS OF 3 HPA/3 HOURS ARE ALREADY BEING OBSERVED IN NORTH CENTRAL MT AS OF MID EVENING AS WARM AIR ADVECTION RAMPS UP ALOFT. AS THIS TIGHTENS THE LOW-LEVEL PRESSURE GRADIENT AROUND LIVINGSTON...WINDS COULD GET STRONG LATE TONIGHT AND WED MORNING...WHICH IS SUPPORTED BY THE 18 UTC MAV AND 00 UTC MET GUIDANCE. WE THUS INCREASED WINDS IN THE GRIDDED FORECAST NEAR LIVINGSTON FROM 09 TO 18 UTC...AND IT WOULDN/T BE TOO SURPRISING IF WE END UP NEEDING A WIND ADVISORY IN THAT AREA BEFORE ALL IS SAID AND DONE. SCHULTZ .LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE... THE EXTENDED FORECAST BEGINS ON FRIDAY WITH THE ARCTIC AIRMASS FINALLY RETREATING EASTWARD INTO THE DAKOTAS. NORTHWESTERLY FLOW WILL REMAIN IN PLACE ALOFT...WITH A SHORTWAVE TROUGH PASSING ACROSS THE FORECAST AREA DURING THE DAY FRIDAY. THIS WILL CAUSE A SURFACE LOW TO TRACK FROM CANADA ACROSS NORTHEAST MONTANA...ACTING TO TIGHTEN THE PRESSURE GRADIENT ACROSS THE FORECAST AREA. THIS SURFACE PRESSURE GRADIENT WILL COMBINE WITH WARM ADVECTION AT MOUNTAIN TOP LEVEL AND WESTERLY 700 MB WINDS UP TO 45 KTS TO CREATE A FAVORABLE PERIOD FOR STRONG WINDS FROM LIVINGSTON TO BIG TIMBER TO NYE. GUSTY WINDS WESTERLY WINDS WILL SPREAD ACROSS THE PLAINS BEHIND THE SURFACE FRONT AS WINDS TURN TO THE NORTHWEST. PRECIPITATION CHANCES WILL BE LIMITED FROM BILLING WEST DUE TO STRONG DOWNSLOPE FLOW COUNTERACTING THE QG FORCING FROM THE WAVE...BUT SNOW SHOWERS WILL HAVE A BETTER CHANCE OF DEVELOPING EAST OF BILLINGS WHERE THE DOWNSLOPE WILL HAVE LESS INFLUENCE. THE NEXT SYSTEM OF INTEREST WILL BE ANOTHER WIND EVENT IN THE SUNDAY TIME FRAME AS ANOTHER SHORTWAVE TRAVERSES THE FORECAST AREA. HAVE HIT THE WINDS A LITTLE HARDER IN THE FORECAST GRIDS TO SHOW THIS TREND. OTHERWISE TEMPERATURES WILL REMAIN SEASONABLE TO SLIGHTLY ABOVE AVERAGE THROUGH THE EXTENDED FORECAST. THE WEATHER PATTERN LOOKS PRETTY QUIET TO START NEXT WEEK AS RIDGE BUILDS IN ALOFT. CHURCH && .AVIATION... IFR TO MVFR CONDITIONS DUE TO LOW CEILINGS AND VISIBILITY IN SNOW WILL LINGER OVER EASTERN ROUTES FROM KMLS TO K97M THROUGH ABOUT 05Z WITH GRADUAL IMPROVEMENT TO MAINLY VFR. STRONG NW WINDS IN THESE AREAS WILL ALSO DECREASE TO UNDER 15 KTS AFTER 07Z. VFR WILL OTHERWISE PREVAIL ACROSS THE REST OF THE FORECAST AREA OVERNIGHT. STRONG SW WINDS WILL DEVELOP IN THE KLVM VICINITY AFTER 09Z WITH GUSTS NEAR 40 KTS POSSIBLE. UNSETTLED CONDITIONS WILL DEVELOP AGAIN ON WEDNESDAY WITH SOME AREAS FROM KBIL EAST AND SOUTH EXPECTED TO HAVE MVFR TO IFR CONDITIONS. MOUNTAINS MAY BE OBSCURED ON WEDNESDAY AS WELL. BT && .PRELIMINARY POINT TEMP/POPS... WED THU FRI SAT SUN MON TUE ----------------------------------------------------------- BIL 005/023 007/027 022/043 023/045 028/049 028/046 026/048 36/S 65/J 22/W 00/B 01/N 11/N 11/B LVM 009/035 020/038 028/046 025/048 030/049 029/046 030/048 56/O 75/W 22/W 11/N 11/N 11/N 11/N HDN 002/020 005/022 018/043 017/044 020/047 025/043 023/045 38/S 87/J 22/W 00/B 01/U 11/U 11/U MLS 904/008 908/010 009/035 016/038 019/041 023/039 023/041 26/S 65/J 22/J 10/B 01/U 11/B 11/U 4BQ 901/014 902/016 010/039 016/041 020/043 024/041 021/043 46/S 76/J 22/J 00/U 00/U 11/B 11/U BHK 909/002 915/006 000/034 017/034 019/037 020/037 021/039 64/S 42/J 22/J 10/B 00/U 01/B 11/B SHR 004/022 005/026 019/042 016/046 017/048 023/044 025/046 37/S 87/J 22/J 00/U 00/U 11/U 11/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...WIND CHILL ADVISORY IN EFFECT UNTIL 9 AM MST WEDNESDAY FOR ZONES 32-33-37. WINTER WEATHER ADVISORY IN EFFECT FROM 6 AM WEDNESDAY TO NOON MST THURSDAY FOR ZONES 38-57-58. WY...WINTER WEATHER ADVISORY IN EFFECT FROM 6 AM WEDNESDAY TO NOON MST THURSDAY FOR ZONES 98-99. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1201 AM CST WED JAN 30 2013 .AVIATION...06Z KGRI TAF. THE BACK END OF THE SNOW SHIELD WILL CONTINUE TO SLIDE SOUTHEAST AND EXPECT THE SNOW SHOULD COME TO AN END AT KGRI BY AROUND 08Z. VISIBILITY AND CEILINGS SHOULD ALSO SHOW SOME IMPROVEMENT ONCE THE SNOW MOVES OUT. HOWEVER...THE WIND WILL REMAIN GUSTY OUT OF THE NORTHWEST THROUGH AT LEAST MID AFTERNOON. && .PREV DISCUSSION... /ISSUED 1045 PM CST TUE JAN 29 2013/ UPDATE...RADAR RETURNS FROM KUEX THROUGH THE PAST HOUR OR SO INDICATE BANDED PRECIPITATION CONTINUING OVER THE SOUTHEASTERN ONE-THIRD OF THE CWA. ADVISORY WAS RIGHT ON FOR THE MOST PART...EXCEPT INCREASED SNOWFALL RATES WERE ALSO BEING INDICATED OVER NORTH CENTRAL KANSAS AND AS A RESULT...OPTED TO EXTEND THE ADVISORY TO ALSO INCLUDE MITCHELL...OSBORNE...AND SMITH COUNTIES IN KANSAS...AS WELL AS WEBSTER COUNTY IN NEBRASKA. ALSO...ALTHOUGH IT APPEARS THE HEAVIEST SNOWFALL SHOULD BE COMING TO AN END AROUND 01Z...THE ENDING TIME APPEARED A LITTLE TOO CLOSE FOR COMFORT WITH RESPECT WITH THE HEADLINE. IN ADDITION...AN INCREASING NORTH WIND IS ALSO EXPECTED TO PROMOTE RESTRICTED VISIBILITY IN BLOWING SNOW THROUGH SUNRISE WEDNESDAY. GIVEN ALL THIS...WENT AHEAD AND ALSO EXTENDED THE ADVISORY TO 12Z. PREV DISCUSSION... /ISSUED 728 PM CST TUE JAN 29 2013/ UPDATE...EVENING UPPER AIR ANALYSIS INDICATES A LONGWAVE TROUGH OVER THE CENTRAL CONUS...WITH RIDGING OVER THE EAST AND WEST. MID AND UPPER LEVEL JET ENERGY EXTENDS SOUTH/SOUTHEAST FROM SOUTHWEST CANADA INTO THE FOUR CORNERS REGION...AND THEN EAST INTO THE SOUTHERN PLAINS BEFORE TURNING NORTHEAST ACROSS PORTIONS OF THE CENTRAL PLAINS AND MISSISSIPPI VALLEY. ALTHOUGH THE PRIMARY AXIS OF THIS JET ENERGY REMAIN JUST EAST/SOUTHEAST OF OUR CWA...RAP DATA DOES SUGGEST WIND SPEEDS GENERALLY RANGING FROM 50-100KTS IN EXISTENCE FROM WEST TO EAST ACROSS OUR CWA AROUND 400MB...WITH THE STRONGEST WIND RESIDING ACROSS OUR EAST. WATER VAPOR IMAGERY SHOWS INCREASED VALUES OF MID LEVEL MOISTURE EXTENDING FROM EASTERN TEXAS...NORTHEAST INTO THE MID MISSISSIPPI VALLEY...AND A MID LEVEL DRY INTRUSION WORKING INTO THE CENTRAL PLAINS. AT THE SURFACE A COLD FRONT IS NOTED EXTENDING FROM CENTRAL MISSOURI...SOUTHWEST INTO PORTIONS OF KANSAS...OKLAHOMA AND TEXAS. OUR CWA IS CURRENTLY ON THE BACK SIDE OF THIS FRONT WITH A NORTHERLY LOW LEVEL WIND FIELD PREVAILING ACROSS THE AREA AS A RESULT. RADAR DATA FROM KUEX INDICATES BANDED PRECIPITATION OVER THE SOUTHEASTERN HALF OF OUR CWA...HOWEVER COMMUNICATION WITH OBSERVERS HAVE YIELDED LITTLE MORE THAN TRACE REPORTS OF SNOWFALL ACCUMULATION THIS EVENING...ALTHOUGH ACCUMULATION IS UNDOUBTEDLY BEGINNING TO OCCUR ALONG AND EAST OF HIGHWAY 281 NOW. GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL SUGGEST PORTIONS OF THE LONGWAVE TROUGH NEAR OUR AREA WILL STRENGTHEN INTO A SHORT WAVE FEATURE AS IT PUSHES OVER PORTIONS OF NEBRASKA AND KANSAS...AND EVENTUALLY INTO IOWA AND MISSOURI TONIGHT. AS MID LEVEL VORTICITY INCREASES WITH THE STRENGTHENING MID LEVEL SHORT WAVE...SO WILL MID LEVEL DEFORMATION TO THE WEST/NORTHWEST OF THE MID LEVEL SHORT WAVE AXIS...WITH THE PRIMARY AXIS OF MID LEVEL DEFORMATION EXPECTED TO PERSIST FROM EASTERN NEBRASKA...INTO PORTIONS OF SOUTH CENTRAL NEBRASKA AND NORTH CENTRAL KANSAS THIS EVENING...AND THEN EAST INTO WESTERN IOWA AND SOUTHEASTERN NEBRASKA BY 06Z TONIGHT. THIS AXIS OF DEFORMATION AND RESULTANT MID LEVEL FRONTOGENESIS...PRIMARILY NEAR 700MB...WILL CONTINUE TO PROVIDE BANDED PRECIPITATION ACROSS PORTIONS OF OUR AREA THROUGH AT LEAST 06Z...WITH THE EAST/SOUTHEASTERN PORTIONS OF OUR CWA STILL UNDER THE GUN TO RECEIVE A DECENT ROUND OF FRESH SNOWFALL THIS EVENING. FORECAST CROSS SECTIONS ALSO INDICATE A WEAK ZONE OF -EPV WILL PERIODICALLY EXIST JUST ABOVE THE MID LEVEL FRONTOGENESIS THIS EVENING...WHICH INDICATES AT LEAST SOME SLANT- WISE CONVECTION AND A POSSIBILITY FOR INCREASED PRECIPITATION RATES. THE CURRENT THINKING IS THAT THIS AREA OF BANDED PRECIPITATION WILL CONTINUE SHIFTING EAST/NORTHEAST ALONG WITH THE PRIMARY AXIS OF MID LEVEL FRONTOGENESIS THROUGH TONIGHT...WITH PRECIPITATION RATES INCREASING AS THE AFOREMENTIONED MID LEVEL FRONTOGENESIS ALSO INTENSIFIES ACROSS EAST/SOUTHEASTERN PORTIONS OF OUR CWA. PRECIPITATION SHOULD THEN TAPER OFF ACROSS OUR CWA STARTING AROUND 06Z AS THE PRIMARY AXIS OF MID LEVEL FRONTOGENESIS ALSO MOVES EAST OF OUR AREA. THIS IS A SOLUTION SUPPORTED BY QPF FIELDS FROM THE NAM...OPERATIONAL GFS...EC...SREF-MEAN...RAP...HRRR...AND 4KM WRF- NMM. EXACT LIQUID PRECIPITATION AMOUNTS VARY FROM MODEL TO MODEL...BUT IN GENERAL THEY AVERAGE BETWEEN 0.1" AND 0.2" ACROSS OUR SOUTHEAST. WITH LOWER TROPOSPHERIC TEMPERATURE EXPECTED TO AVERAGE IN THE UPPER 20S TO NEAR 30 DEGREES F...WILL GO AHEAD AND ASSUME AN AVERAGE SNOW-WATER RATIO OF 12:1...WHICH PRESENTS SNOWFALL ACCUMULATION GENERALLY IN THE 1-2.5" RANGE. GIVEN THE POTENTIAL FOR MODEST SLANT-WISE CONVECTION HOWEVER...WILL GO AHEAD AND ADD ANOTHER INCH TO THE MODEL OUTPUT WHICH PROVIDES SNOWFALL ACCUMULATION CLOSER TO THE 2-4" RANGE. IN ADDITION TO THE SNOWFALL...LOW LEVEL PRESSURE RISES BEHIND THE LOW LEVEL BAROCLINIC ZONE...CURRENTLY TO OUR SOUTH...ARE EXPECTED TO INDUCE A STRENGTHENING LOW LEVEL PRESSURE GRADIENT TONIGHT. GUIDANCE FROM THE MET AND MAV SUGGEST A SUSTAINED WIND AVERAGING BETWEEN 15 AND 20KTS...WITH LOCALLY HIGHER GUSTS...WILL BE COMMON ACROSS OUR CWA DURING THE SNOWFALL WHICH WILL CERTAINLY CREATE SOME VISIBILITY RESTRICTION IN BLOWING SNOW. OVERALL THE TIMING AND POSITION OF THE CURRENT WINTER WEATHER ADVISORY ARE IN GREAT SHAPE...SO MADE NO CHANGES THERE. OUR FORECAST SNOWFALL AMOUNTS DID SEEM A TOUCH ON THE HIGH SIDE BASED ON THE LATEST MODEL OUTPUT...SO DID GO AHEAD AND DECREASE SNOWFALL ACCUMULATION DOWN INTO THE 2-4" RANGE FOR THE ADVISORY AREA. REMAINDER OF THE FORECAST REMAINS IN GREAT SHAPE WITH ONLY MINOR CHANGES MADE TO HOURLY TEMPERATURE...WIND AND DEWPOINTS GRIDS TO BETTER REFLECT CURRENT CONDITIONS. PREV DISCUSSION... /ISSUED 358 PM CST TUE JAN 29 2013/ SHORT TERM...TONIGHT AND WEDNESDAY. HIGHLY AMPLIFIED MEAN TROUGH IS HEADING EAST WITH THE AXIS CROSSING INTO THE HIGH PLAINS. STRONG JET AHEAD OF THIS AXIS WITH STIFF MID-LEVEL FRONTOGENETIC FORCING PREDICTED TO RAMP UP THIS EVENING. THIS IS SUPPORTED BY THE NAM...HRRR...ECMWF...AND GFS...ALL PLACING DECENT QPF AMOUNTS IN THE EAST/SOUTHEAST PART OF THE CWA AT THE VERY LEAST. THIS AGREEMENT AMONG MODELS HAS LED ME TO INCREASE CHANCES OF PRECIPITATION EVEN MORE. SOUNDINGS INDICATE THAT THIS WILL BE A SNOW EVENT AND HAVE GONE WITH ONLY SNOW AS THE PRECIPITATION TYPE...AS OPPOSED TO MENTIONING RAIN AT ONSET. THE HRRR INDICATE4D QUITE A RAMP UP IN QPF PRODUCTION BY EARLY AFTERNOON...WHICH PROMPTED ME TO GO WITH AN ADVISORY FOR MOST OF OUR EASTERN CWA. I FELT INCLINED TO DO THIS AS NORTH/NORTHWEST WIND WILL RAMP UP CONSIDERABLY TONIGHT AS THE SURFACE PRESSURE GRADIENT INCREASES. I INCREASED WIND SPEEDS A BIT MORE FROM THE PREVIOUS FORECAST FOR TONIGHT INTO WEDNESDAY. SNOW SHOULD WIND DOWN FAIRLY QUICKLY AS THE TROUGH AXIS HEADS TO THE EAST BY THE OVERNIGHT. LEFT THE SLIGHT CHANCE OF FLURRIES IN OUR NORTHEAST FOR WEDNESDAY MORNING...BUT I DID NOTICE THE NAM PULLING BACK A LITTLE ON STRATUS...WHICH USUALLY INDICATES A LACK OF FLURRY POTENTIAL...BUT CLOSE ENOUGH FOR ME TO LEAVE IN FOR NOW. WIND SHOULD REMAIN BELOW WIND ADVISORY CRITERIA FOR WEDNESDAY...ALTHOUGH OUR FAR NORTH MAY FLIRT WITH IT...JUDGING BY PREDICTED MOMENTUM TRANSFER. KEPT SKY COVER GENERALLY CLOUDY...ALTHOUGH THERE COULD BE SOME BREAKS...ESPECIALLY IN THE SOUTH BY AFTERNOON. KEPT TEMPERATURES THE SAME FOR TONIGHT AND WEDNESDAY FROM PREVIOUS FORECAST AS THEY LOOKED LIKE THEY WERE RIGHT ON TARGET. LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY. MAIN FORECAST CONCERN IN THE EXTENDED WILL BE THE TEMPERATURES. STARTING WED EVENING...THE BIG PICTURE SHOWS THE CENTRAL U.S. IN NORTHWEST FLOW AS THE UPPER TROUGH IS SLATED TO BE MOVING INTO THE MIDWEST WITH RIDGING MOVING ONTO THE PACIFIC NORTHWEST COAST. AS THE WORK WEEK ROLLS ALONG IT APPEARS WE WILL PRETTY MUCH STAY IN THIS TYPE OF FLOW WITH OVERALL RIDGING TO THE WEST AND TROUGHING EAST. WILL MOST LIKELY HAVE A FEW CLIPPER LIKE WAVES SLIDE THROUGH OUR REGION UNDER THIS TYPE OF PATTERN AND THE QUESTION IS WILL THEY BRING ANY ADDITIONAL PRECIPITATION CHANCES. BASIC ANSWER IS NO ALTHOUGH WE DO HAVE A CHANCE OF FLURRIES MENTIONED FOR WED NIGHT AND THURSDAY IN THE CURRENT FORECAST AND WILL GO AHEAD AND KEEP THEM IN GIVEN SUFFICIENT MOISTURE AND COLDER TEMPERATURES NOTED IN MODEL FORECAST SOUNDINGS. OTHERWISE WILL LEAVE THE REST OF THE FORECAST DRY ALTHOUGH SOME LIGHT PRECIPITATION NOT TOTALLY OUT OF THE QUESTION FOR FRIDAY. AS FAR AS TEMPERATURES GO...IT WILL REMAIN QUITE CHILLY WED NIGHT INTO FRIDAY MORNING AS ADDITIONAL COLD AIR SLIDES DOWN FROM THE NORTH...ALTHOUGH THE BITTER COLD AIR SHOULD REMAIN JUST NORTHEAST OF THE CWA. STOUT NORTHWEST WINDS ARE ALSO EXPECTED AGAIN FOR THURSDAY AFTERNOON AS WE SIT BETWEEN 1038 MB HIGH PRESSURE OVER MONTANA/NDAK AND LOW PRESSURE ACROSS MISSOURI AND KANSAS. FRIDAY MORNING MIGHT BE THE COLDEST DAY OF THE WEEK DEPENDING ON WHETHER HIGH PRESSURE DROPS RIGHT OVER THE TOP OF US OR SLIDES A LITTLE TO THE EAST IN WHICH CASE WE MIGHT HAVE A MORE CLOUD COVER AND LIGHT SOUTHERLY FLOW. GOING INTO THE WEEKEND HEIGHTS BEGIN TO RISE AS WESTERN RIDGE STARTS TO MOVE EAST AND AT THIS POINT APPEARS BOTH SAT AND SUNDAY SHOULD BE CLOSE TO 50 DEGREES. ANOTHER WEAK FRONT IS EXPECTED TO PUSH ACROSS SUNDAY NIGHT OR MONDAY WITH HIGH TEMPERATURES FALLING A TAD BUT STILL ABOVE SEASONAL LEVELS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...WINTER WEATHER ADVISORY UNTIL 6 AM CST WEDNESDAY FOR NEZ049-063- 064-076-077-085>087. KS...WINTER WEATHER ADVISORY UNTIL 6 AM CST WEDNESDAY FOR KSZ006-007- 018-019. && $$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1045 PM CST TUE JAN 29 2013 .UPDATE...RADAR RETURNS FROM KUEX THROUGH THE PAST HOUR OR SO INDICATE BANDED PRECIPITATION CONTINUING OVER THE SOUTHEASTERN ONE-THIRD OF THE CWA. ADVISORY WAS RIGHT ON FOR THE MOST PART...EXCEPT INCREASED SNOWFALL RATES WERE ALSO BEING INDICATED OVER NORTH CENTRAL KANSAS AND AS A RESULT...OPTED TO EXTEND THE ADVISORY TO ALSO INCLUDE MITCHELL...OSBORNE...AND SMITH COUNTIES IN KANSAS...AS WELL AS WEBSTER COUNTY IN NEBRASKA. ALSO...ALTHOUGH IT APPEARS THE HEAVIEST SNOWFALL SHOULD BE COMING TO AN END AROUND 01Z...THE ENDING TIME APPEARED A LITTLE TOO CLOSE FOR COMFORT WITH RESPECT WITH THE HEADLINE. IN ADDITION...AN INCREASING NORTH WIND IS ALSO EXPECTED TO PROMOTE RESTRICTED VISIBILITY IN BLOWING SNOW THROUGH SUNRISE WEDNESDAY. GIVEN ALL THIS...WENT AHEAD AND ALSO EXTENDED THE ADVISORY TO 12Z. && .PREV DISCUSSION... /ISSUED 728 PM CST TUE JAN 29 2013/ UPDATE...EVENING UPPER AIR ANALYSIS INDICATES A LONGWAVE TROUGH OVER THE CENTRAL CONUS...WITH RIDGING OVER THE EAST AND WEST. MID AND UPPER LEVEL JET ENERGY EXTENDS SOUTH/SOUTHEAST FROM SOUTHWEST CANADA INTO THE FOUR CORNERS REGION...AND THEN EAST INTO THE SOUTHERN PLAINS BEFORE TURNING NORTHEAST ACROSS PORTIONS OF THE CENTRAL PLAINS AND MISSISSIPPI VALLEY. ALTHOUGH THE PRIMARY AXIS OF THIS JET ENERGY REMAIN JUST EAST/SOUTHEAST OF OUR CWA...RAP DATA DOES SUGGEST WIND SPEEDS GENERALLY RANGING FROM 50-100KTS IN EXISTENCE FROM WEST TO EAST ACROSS OUR CWA AROUND 400MB...WITH THE STRONGEST WIND RESIDING ACROSS OUR EAST. WATER VAPOR IMAGERY SHOWS INCREASED VALUES OF MID LEVEL MOISTURE EXTENDING FROM EASTERN TEXAS...NORTHEAST INTO THE MID MISSISSIPPI VALLEY...AND A MID LEVEL DRY INTRUSION WORKING INTO THE CENTRAL PLAINS. AT THE SURFACE A COLD FRONT IS NOTED EXTENDING FROM CENTRAL MISSOURI...SOUTHWEST INTO PORTIONS OF KANSAS...OKLAHOMA AND TEXAS. OUR CWA IS CURRENTLY ON THE BACK SIDE OF THIS FRONT WITH A NORTHERLY LOW LEVEL WIND FIELD PREVAILING ACROSS THE AREA AS A RESULT. RADAR DATA FROM KUEX INDICATES BANDED PRECIPITATION OVER THE SOUTHEASTERN HALF OF OUR CWA...HOWEVER COMMUNICATION WITH OBSERVERS HAVE YIELDED LITTLE MORE THAN TRACE REPORTS OF SNOWFALL ACCUMULATION THIS EVENING...ALTHOUGH ACCUMULATION IS UNDOUBTEDLY BEGINNING TO OCCUR ALONG AND EAST OF HIGHWAY 281 NOW. GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL SUGGEST PORTIONS OF THE LONGWAVE TROUGH NEAR OUR AREA WILL STRENGTHEN INTO A SHORT WAVE FEATURE AS IT PUSHES OVER PORTIONS OF NEBRASKA AND KANSAS...AND EVENTUALLY INTO IOWA AND MISSOURI TONIGHT. AS MID LEVEL VORTICITY INCREASES WITH THE STRENGTHENING MID LEVEL SHORT WAVE...SO WILL MID LEVEL DEFORMATION TO THE WEST/NORTHWEST OF THE MID LEVEL SHORT WAVE AXIS...WITH THE PRIMARY AXIS OF MID LEVEL DEFORMATION EXPECTED TO PERSIST FROM EASTERN NEBRASKA...INTO PORTIONS OF SOUTH CENTRAL NEBRASKA AND NORTH CENTRAL KANSAS THIS EVENING...AND THEN EAST INTO WESTERN IOWA AND SOUTHEASTERN NEBRASKA BY 06Z TONIGHT. THIS AXIS OF DEFORMATION AND RESULTANT MID LEVEL FRONTOGENESIS...PRIMARILY NEAR 700MB...WILL CONTINUE TO PROVIDE BANDED PRECIPITATION ACROSS PORTIONS OF OUR AREA THROUGH AT LEAST 06Z...WITH THE EAST/SOUTHEASTERN PORTIONS OF OUR CWA STILL UNDER THE GUN TO RECEIVE A DECENT ROUND OF FRESH SNOWFALL THIS EVENING. FORECAST CROSS SECTIONS ALSO INDICATE A WEAK ZONE OF -EPV WILL PERIODICALLY EXIST JUST ABOVE THE MID LEVEL FRONTOGENESIS THIS EVENING...WHICH INDICATES AT LEAST SOME SLANT- WISE CONVECTION AND A POSSIBILITY FOR INCREASED PRECIPITATION RATES. THE CURRENT THINKING IS THAT THIS AREA OF BANDED PRECIPITATION WILL CONTINUE SHIFTING EAST/NORTHEAST ALONG WITH THE PRIMARY AXIS OF MID LEVEL FRONTOGENESIS THROUGH TONIGHT...WITH PRECIPITATION RATES INCREASING AS THE AFOREMENTIONED MID LEVEL FRONTOGENESIS ALSO INTENSIFIES ACROSS EAST/SOUTHEASTERN PORTIONS OF OUR CWA. PRECIPITATION SHOULD THEN TAPER OFF ACROSS OUR CWA STARTING AROUND 06Z AS THE PRIMARY AXIS OF MID LEVEL FRONTOGENESIS ALSO MOVES EAST OF OUR AREA. THIS IS A SOLUTION SUPPORTED BY QPF FIELDS FROM THE NAM...OPERATIONAL GFS...EC...SREF-MEAN...RAP...HRRR...AND 4KM WRF- NMM. EXACT LIQUID PRECIPITATION AMOUNTS VARY FROM MODEL TO MODEL...BUT IN GENERAL THEY AVERAGE BETWEEN 0.1" AND 0.2" ACROSS OUR SOUTHEAST. WITH LOWER TROPOSPHERIC TEMPERATURE EXPECTED TO AVERAGE IN THE UPPER 20S TO NEAR 30 DEGREES F...WILL GO AHEAD AND ASSUME AN AVERAGE SNOW-WATER RATIO OF 12:1...WHICH PRESENTS SNOWFALL ACCUMULATION GENERALLY IN THE 1-2.5" RANGE. GIVEN THE POTENTIAL FOR MODEST SLANT-WISE CONVECTION HOWEVER...WILL GO AHEAD AND ADD ANOTHER INCH TO THE MODEL OUTPUT WHICH PROVIDES SNOWFALL ACCUMULATION CLOSER TO THE 2-4" RANGE. IN ADDITION TO THE SNOWFALL...LOW LEVEL PRESSURE RISES BEHIND THE LOW LEVEL BAROCLINIC ZONE...CURRENTLY TO OUR SOUTH...ARE EXPECTED TO INDUCE A STRENGTHENING LOW LEVEL PRESSURE GRADIENT TONIGHT. GUIDANCE FROM THE MET AND MAV SUGGEST A SUSTAINED WIND AVERAGING BETWEEN 15 AND 20KTS...WITH LOCALLY HIGHER GUSTS...WILL BE COMMON ACROSS OUR CWA DURING THE SNOWFALL WHICH WILL CERTAINLY CREATE SOME VISIBILITY RESTRICTION IN BLOWING SNOW. OVERALL THE TIMING AND POSITION OF THE CURRENT WINTER WEATHER ADVISORY ARE IN GREAT SHAPE...SO MADE NO CHANGES THERE. OUR FORECAST SNOWFALL AMOUNTS DID SEEM A TOUCH ON THE HIGH SIDE BASED ON THE LATEST MODEL OUTPUT...SO DID GO AHEAD AND DECREASE SNOWFALL ACCUMULATION DOWN INTO THE 2-4" RANGE FOR THE ADVISORY AREA. REMAINDER OF THE FORECAST REMAINS IN GREAT SHAPE WITH ONLY MINOR CHANGES MADE TO HOURLY TEMPERATURE...WIND AND DEWPOINTS GRIDS TO BETTER REFLECT CURRENT CONDITIONS. PREV DISCUSSION... /ISSUED 533 PM CST TUE JAN 29 2013/ AVIATION...00Z KGRI TAF. MVFR CEILINGS EXPECTED THROUGH THE FIRST HALF OF THE TAF PERIOD WITH LIGHT SNOW ALSO EXPECTED TO PERSIST THROUGH VERY EARLY WEDNESDAY MORNING. VISIBILITY RESTRICTION IN BLOWING SNOW WILL ALSO BE POSSIBLE LATER TONIGHT AS THE NORTH WIND INTENSIFIES. VFR CONDITIONS SHOULD BE RESTORED SHORTLY AFTER SUNRISE WEDNESDAY. PREV DISCUSSION... /ISSUED 358 PM CST TUE JAN 29 2013/ SHORT TERM...TONIGHT AND WEDNESDAY. HIGHLY AMPLIFIED MEAN TROUGH IS HEADING EAST WITH THE AXIS CROSSING INTO THE HIGH PLAINS. STRONG JET AHEAD OF THIS AXIS WITH STIFF MID-LEVEL FRONTOGENETIC FORCING PREDICTED TO RAMP UP THIS EVENING. THIS IS SUPPORTED BY THE NAM...HRRR...ECMWF...AND GFS...ALL PLACING DECENT QPF AMOUNTS IN THE EAST/SOUTHEAST PART OF THE CWA AT THE VERY LEAST. THIS AGREEMENT AMONG MODELS HAS LED ME TO INCREASE CHANCES OF PRECIPITATION EVEN MORE. SOUNDINGS INDICATE THAT THIS WILL BE A SNOW EVENT AND HAVE GONE WITH ONLY SNOW AS THE PRECIPITATION TYPE...AS OPPOSED TO MENTIONING RAIN AT ONSET. THE HRRR INDICATE4D QUITE A RAMP UP IN QPF PRODUCTION BY EARLY AFTERNOON...WHICH PROMPTED ME TO GO WITH AN ADVISORY FOR MOST OF OUR EASTERN CWA. I FELT INCLINED TO DO THIS AS NORTH/NORTHWEST WIND WILL RAMP UP CONSIDERABLY TONIGHT AS THE SURFACE PRESSURE GRADIENT INCREASES. I INCREASED WIND SPEEDS A BIT MORE FROM THE PREVIOUS FORECAST FOR TONIGHT INTO WEDNESDAY. SNOW SHOULD WIND DOWN FAIRLY QUICKLY AS THE TROUGH AXIS HEADS TO THE EAST BY THE OVERNIGHT. LEFT THE SLIGHT CHANCE OF FLURRIES IN OUR NORTHEAST FOR WEDNESDAY MORNING...BUT I DID NOTICE THE NAM PULLING BACK A LITTLE ON STRATUS...WHICH USUALLY INDICATES A LACK OF FLURRY POTENTIAL...BUT CLOSE ENOUGH FOR ME TO LEAVE IN FOR NOW. WIND SHOULD REMAIN BELOW WIND ADVISORY CRITERIA FOR WEDNESDAY...ALTHOUGH OUR FAR NORTH MAY FLIRT WITH IT...JUDGING BY PREDICTED MOMENTUM TRANSFER. KEPT SKY COVER GENERALLY CLOUDY...ALTHOUGH THERE COULD BE SOME BREAKS...ESPECIALLY IN THE SOUTH BY AFTERNOON. KEPT TEMPERATURES THE SAME FOR TONIGHT AND WEDNESDAY FROM PREVIOUS FORECAST AS THEY LOOKED LIKE THEY WERE RIGHT ON TARGET. LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY. MAIN FORECAST CONCERN IN THE EXTENDED WILL BE THE TEMPERATURES. STARTING WED EVENING...THE BIG PICTURE SHOWS THE CENTRAL U.S. IN NORTHWEST FLOW AS THE UPPER TROUGH IS SLATED TO BE MOVING INTO THE MIDWEST WITH RIDGING MOVING ONTO THE PACIFIC NORTHWEST COAST. AS THE WORK WEEK ROLLS ALONG IT APPEARS WE WILL PRETTY MUCH STAY IN THIS TYPE OF FLOW WITH OVERALL RIDGING TO THE WEST AND TROUGHING EAST. WILL MOST LIKELY HAVE A FEW CLIPPER LIKE WAVES SLIDE THROUGH OUR REGION UNDER THIS TYPE OF PATTERN AND THE QUESTION IS WILL THEY BRING ANY ADDITIONAL PRECIPITATION CHANCES. BASIC ANSWER IS NO ALTHOUGH WE DO HAVE A CHANCE OF FLURRIES MENTIONED FOR WED NIGHT AND THURSDAY IN THE CURRENT FORECAST AND WILL GO AHEAD AND KEEP THEM IN GIVEN SUFFICIENT MOISTURE AND COLDER TEMPERATURES NOTED IN MODEL FORECAST SOUNDINGS. OTHERWISE WILL LEAVE THE REST OF THE FORECAST DRY ALTHOUGH SOME LIGHT PRECIPITATION NOT TOTALLY OUT OF THE QUESTION FOR FRIDAY. AS FAR AS TEMPERATURES GO...IT WILL REMAIN QUITE CHILLY WED NIGHT INTO FRIDAY MORNING AS ADDITIONAL COLD AIR SLIDES DOWN FROM THE NORTH...ALTHOUGH THE BITTER COLD AIR SHOULD REMAIN JUST NORTHEAST OF THE CWA. STOUT NORTHWEST WINDS ARE ALSO EXPECTED AGAIN FOR THURSDAY AFTERNOON AS WE SIT BETWEEN 1038 MB HIGH PRESSURE OVER MONTANA/NDAK AND LOW PRESSURE ACROSS MISSOURI AND KANSAS. FRIDAY MORNING MIGHT BE THE COLDEST DAY OF THE WEEK DEPENDING ON WHETHER HIGH PRESSURE DROPS RIGHT OVER THE TOP OF US OR SLIDES A LITTLE TO THE EAST IN WHICH CASE WE MIGHT HAVE A MORE CLOUD COVER AND LIGHT SOUTHERLY FLOW. GOING INTO THE WEEKEND HEIGHTS BEGIN TO RISE AS WESTERN RIDGE STARTS TO MOVE EAST AND AT THIS POINT APPEARS BOTH SAT AND SUNDAY SHOULD BE CLOSE TO 50 DEGREES. ANOTHER WEAK FRONT IS EXPECTED TO PUSH ACROSS SUNDAY NIGHT OR MONDAY WITH HIGH TEMPERATURES FALLING A TAD BUT STILL ABOVE SEASONAL LEVELS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...WINTER WEATHER ADVISORY UNTIL 6 AM CST WEDNESDAY FOR NEZ049-063- 064-076-077-085>087. KS...WINTER WEATHER ADVISORY UNTIL 6 AM CST WEDNESDAY FOR KSZ006-007- 018-019. && $$ 1045 PM UPDATE/0728 PM UPDATE/AVIATION...BRYANT SHORT TERM...HEINLEIN LONG TERM...EWALD
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
109 AM EST WED JAN 30 2013 .SYNOPSIS... WARM TEMPERATURES WILL BE IN PLACE AHEAD OF A COLD FRONT THAT WILL ARRIVE WEDNESDAY. STRONG STORMS ORGANIZED AHEAD OF THE FRONT WILL AFFECT OUR AREA DURING THE EARLY TO MID MORNING HOURS WEDNESDAY. BEHIND THIS SYSTEM...COLDER AIR WILL RETURN TO THE REGION FOR THE REMAINDER OF THE WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... MODELS KEEP OFFERING SUBTLE TIMING ISSUES FOR THE ARRIVAL OF A PREFRONTAL TROUGH LATE TONIGHT INTO WEDNESDAY MORNING THAT WILL MOSTLY LIKELY BE REALIZED AS A WELL DEFINED BAND OF SHOWERS AND EMBEDDED THUNDERSTORMS. DID NOT WANT TO MESS WITH THE TIMING TOO MUCH UNTIL WE CAN GET A MORE DEFINED TRACK TO OUR WEST AND WITH A CHANCE TO LOOK AT THE FULL SUITE OF MODELS BOTH HIGH RES/CONVECTIVE ALLOWING AND LOWER RES/CONVECTIVE PARAMETRIZATION. IT APPEARS THAT THE LATEST 00Z NAM-WRF TRICKLING IN IS NOT DEPICTING ANY MUCAPE WITH CURRENT CONVECTION TO OUR WEST/NORTHWEST WHILE THE LATEST RAP AT LEAST SHOWS 200-400 J/KG. BY THE TIME THE LINE ARRIVES LATE TONIGHT INTO WEDNESDAY...BEST ESTIMATE OF MUCAPE SHOULD STILL BE IN THE 200-400 J/KG. EVEN IF THIS DOES NOT RESULT IN MUCH LIGHTNING ACTIVITY...A VERY STRONG 925 MB TO 850 MB LOW LEVEL JET WILL ACCOMPANY IT...AND IT CAN NOT BE TAKEN LIGHTLY. IT WOULD NOT TAKE MUCH FOR CONVECTIVE DOWNDRAFTS TO BRING DOWN 50 KNOT WINDS TO THE SURFACE WHEN THEY ARE FORECAST TO BE IN THE LOWER 50S KNOTS AROUND 1500 FEET. SO...CURRENT HWO HIGHLIGHTS THIS. ANOTHER CONCERN WILL BE THE THREAT FOR HIGHER WIND GUSTS BEFORE THE LINE OF ARRIVES SHOULD SOME STRAY SHOWER ACTIVITY PRECEDE IT WHICH MAY BRING DOWN STRONGER WINDS DUE TO LIGHT SPRINKLES OR VIRGA. WILL CONTINUE TO MONITOR THIS. TEMPERATURES OVERNIGHT WILL REMAIN VERY WARM DUE TO INCREASING SOUTHERLY FLOW AHEAD OF THE PREFRONTAL TROUGH AND SHOULD BOTTOM OUT IN THE UPPER 50S TO THE LOWER 60S BY SUNRISE. && .SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/... BEHIND THE LEADING EDGE OF THIS CONVECTIVE COMPLEX WILL BE AN AREA OF MORE STRATIFORM PRECIPITATION AND LIGHTER WINDS THAT WILL LAST INTO THE MID MORNING HOURS IN THE WEST...AND THE EARLY AFTERNOON IN THE EAST. ALL THIS ACTIVITY WILL BE PRE-FRONTAL...THEREFORE A MARKED TEMPERATURE DECREASE WILL NOT BE EXPECTED UNTIL LATER IN THE AFTERNOON AS THE FRONT PASSES. SOME SHOWER ACTIVITY IS EXPECTED AS THE FRONT PASSES WITH A WIND SHIFT OUT THE NORTHWEST. WINDS WILL BECOME GUSTY FROM THE AFTERNOON INTO THE LATE EVENING BEHIND THE FRONT. WITH THE LOW RAPIDLY DEPARTING...DO NOT EXPECT WINDS TO GUST MUCH OVER 40 MPH BEHIND THE FRONT. CAA SNOW SHOWERS WILL BE POSSIBLE DURING THE EVENING BEHIND THE FRONT...BEFORE THE ORIENTATION OF THE FLOW BECOMES MORE WESTERLY...ENDING ANY SNOW SHOWERS LATE WEDNESDAY NIGHT. BREEZY CONDITIONS WILL CONTINUE THURSDAY AS HIGH PRESSURE TRIES TO BUILD SOUTHEASTWARD ACROSS THE PLAINS. A WEAK DISTURBANCE RIDING UNDERNEATH THE BASE OF A DEEP TROUGH CENTERED OVER EASTERN CANADA WILL PASS ACROSS OUR AREA THURSDAY NIGHT. MODELS VARY A BIT IN THEIR STRENGTH OF THIS FEATURE AND IN THE MOISTURE AVAILABLE FOR IT TO WORK WITH. CURRENT INDICATIONS ARE THAT SOME OF OUR FORECAST AREA...PARTICULARLY THE SOUTH...MAY SEE SOME SNOW OVERNIGHT THURSDAY NIGHT. && .LONG TERM /FRIDAY THROUGH TUESDAY/... A SHORTWAVE WILL BE DEPARTING THE GREAT LAKES REGION ON FRIDAY...WITH CLOUDS REMAINING OVER THE UPPER OHIO VALLEY TO START THE PERIOD. IT APPEARS THAT THE SNOW WILL BE LIMITED TO AREAS NORTHEAST OF THE ILN CWA BY FRIDAY...SO NO POPS HAVE BEEN INCLUDED IN THE FORECAST. THE AIR MASS ON FRIDAY WILL BE VERY COLD...WITH 850MB TEMPERATURES OVER THE CWA RANGING FROM -16 TO -20 DEGREES CELSIUS. STANDARDIZED ANOMALIES INDICATE THESE TEMPERATURES APPROACH 2 STANDARD DEVIATIONS BELOW NORMAL...NOT AS SIGNIFICANT AS THE ARCTIC AIR LAST WEEK...BUT STILL RATHER COLD. MAX TEMPS ON FRIDAY HAVE BEEN LOWERED SLIGHTLY...THOUGH NOT AS COLD AS THE RAW GFS. THROUGH THE REST OF THE PERIOD...OVERALL MODEL AGREEMENT IN THE LARGE-SCALE PATTERN IS GOOD THROUGH MONDAY. ON MONDAY AND LATER...GFSE SPREADS BECOME FAIRLY LARGE...WITH LESS CERTAINTY IN THE STRENGTH AND TIMING OF THE NEXT WEATHER SYSTEMS TO IMPACT THE REGION. ON SATURDAY...A WEAK NORTHWEST FLOW SYSTEM WILL MOVE THROUGH THE REGION. WITH SOME INCREASING CONFIDENCE IN THE TIMING OF THIS SYSTEM...POPS WERE INCREASED WELL INTO THE CHANCE CATEGORY FOR THE WHOLE CWA. VERIFYING AS CURRENTLY DEPICTED IN THE MODELS...THIS SYSTEM COULD PRODUCE AN INCH OR TWO OF SNOW. TEMPERATURES WILL GRADUALLY MODERATE OVER THE NEXT FEW DAYS...AS SURFACE HIGH PRESSURE BUILDS IN BEHIND THE SATURDAY SYSTEM. THE TEMPERATURE FORECAST HAS BEEN INCREASED SLIGHTLY THROUGH MONDAY. A COLD FRONT IS FORECAST TO MOVE THROUGH THE CWA ON MONDAY NIGHT. WHILE THE GFS/ECMWF ARE IN DECENT AGREEMENT ON TIMING...THE STRENGTH OF THE FRONT AND AMOUNT OF MOISTURE AVAILABLE REMAIN UNCERTAIN. TEMPERATURES WITH THIS FRONT WILL LIKELY SUPPORT A MIX OF RAIN OR SNOW...WITH NOTHING INDICATING ICY PRECIPITATION AT THIS TIME. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... DYNAMIC WX SYSTEM WILL AFFECT THE REGION TODAY. LINE OF CONVECTION ASSOCIATED WITH A PRE FRONTAL TROF IS OVER WRN INDIANA ATTM. HAVE THIS TIMED TO THE WRN TAFS AROUND 10Z. CIGS AND VSBYS WILL DROP TO AT LEAST MVFR WITH THE LINE. LIGHTNING WITH THE LINE HAS BEEN WAINING OVER THE LAST COUPLE OF HOURS...SO CONTINUED WITH ONLY A VCTS ATTM. WINDS ALOFT WITH THIS SYSTEM ARE OVER 50 KTS. QUESTION IS WHETHER THESE WINDS WILL BE REALIZED AT THE TAF SITES. DECIDED TO GO WITH GUSTS TO 40 KTS ATTM. HAVE THE CONVECTION TIMED E OF CMH BY 13-15Z. DIRECTLY BEHIND THE CONVECTION...WINDS SHOULD TURN TO THE NW ALONG WITH MVFR CIGS AND VSBYS IN LINGERING SHRA FOR A FEW HOURS. WINDS WILL GRADUALLY TURN BACK TO THE NW AHEAD OF THE MAIN CDFNT BY LATE MORNING IN THE W AND EARLY AFTN IN THE E. STRONG CDFNT REACHES THE WRN TAFS AROUND 00Z. THE CAA BEHIND THE FNT WILL PULL DOWN STRONG AIR ALOFT. EXPECT GUSTS AGAIN OVER 35 KTS POST FRONTAL. ALONG WITH THE STRONG WINDS CIGS WILL DROP BACK TO MVFR AND THERE WILL BE A CHANCE OF SHRA. OUTLOOK...BREEZY TO WINDY CONDITIONS TO CONTINUE WEDNESDAY NIGHT INTO THURSDAY. MVFR CEILINGS TO CONTINUE THURSDAY INTO THURSDAY NIGHT WITH MVFR VSBYS POSSIBLE THURSDAY NIGHT. MVFR CONDITIONS POSSIBLE AGAIN SATURDAY INTO SATURDAY NIGHT. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HICKMAN/LATTO NEAR TERM...HICKMAN/LATTO SHORT TERM...LATTO LONG TERM...HATZOS AVIATION...SITES
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1150 PM CST TUE JAN 29 2013 .UPDATE...FOR 06Z AVIATION DISCUSSION. && .AVIATION...06Z AVIATION DISCUSSION. STILL GENERALLY BELIEVE THAT MAIN IMPACTS FROM A LINE OF STORMS MOVING THRU WRN TN AT THIS TIME WILL BEGIN IMPACTING CKV AROUND 30/07Z...BNA 30/08Z...AND CSV 30/11Z. SOME BRIEF HEAVY RAINFALL POTENTIAL WILL ALSO ACCOMPANY THE STRONGER STORMS...WITH SFC GUSTS TO 45KTS POSSIBLE IF NOT HIGHER...WITH ISO SVR TSTMS CERTAINLY NOT OUT OF THE QUESTION. STILL TIMING AND DURATION UNCERTAINTIES ABOUND...HOWEVER CKV/BNA CAN EXPECT THE STRONGEST STORMS TO MOVE OUT OF VCNTY 30/11-30/12Z. CSV MAY CONTINUE TO EXPERIENCE STRONGEST STORMS UNTIL AROUND 30/15Z. WINDS ARE STILL EXPECTED TO REMAIN AROUND 20 KTS WITH GUSTS TO 30 KTS FOR AREA THRU 30/24Z. CHANGE OVER TO ALL SHWRS IS EXPECTED W TO E DURING 30/18Z-31/00Z TOO. SOME WRAP AROUND MOISTURE POSSIBLE...ALONG WITH WEAK INSTABILITY ASSOCIATED WITH UPPER LEVEL TROUGH PASSAGE...TO SUPPORT A RAIN/SNOW MIX CSV FROM 31/02Z-31/06Z. && .PREV DISCUSSION.../ISSUED 839 PM CST TUE JAN 29 2013/ UPDATE... VWP CONTINUING TO SHOW A GRADUAL INCREASE IN WIND SPEEDS...PARTICULARLY SEVERAL THOUSAND FEET ABOVE GROUND. MODELS STILL INDICATING SOME LOWER LEVEL SUBSIDENCE OUT AHEAD OF THE CONVECTION TO OUR WEST. LATEST TN STATE ROUNDUP SHOWING SOME 30 TO 35 MPH GUSTS ACROSS WESTERN TN. THESE HIGHER SPEEDS WILL CONTINUE TO MOVE OUR WAY OVERNIGHT. CONVECTION WISE...TWO MAIN AREAS OF PRE FRONTAL FORCING INDICATED ACROSS CENTRAL AND EASTERN AR NOW. ITS LOOKING AS THOUGH THE LEADING LINE WILL REACH THE MS RIVER AROUND 04Z OR 05Z. THERE IS A LEADING AREA OF CONVECTION ACROSS NRN MS BUT IT APPEARS TO BE OUTRUNNING THE BETTER INSTABILITY AT THIS TIME. LATEST HRRR DATA SHOWS THE MAIN LINE OF STORMS REACHING THE TN RIVER AROUND 08Z. LATEST NAM DATA STILL SHOWING A GOOD DEAL OF INSTABILITY WITH NEG SHOWALTER VALUES TRAVERSING THE AREA. FURTHERMORE...HELICITY VALUES REMAIN QUITE HIGH. THUS...THE TORNADO WATCHES TO OUR WEST ARE LIKELY TO PROPAGATE EASTWARD OVERNIGHT. NAM CONTINUES TO RUN A FEW HOURS TOO SLOW WITH THE EXPECTED CONVECTION. NEAR 60 DEW POINTS NOW COVER THE BULK OF OUR AREA...WITH SOME LOWER TO MID 60S DEWPOINTS ACROSS SOUTHERN MIDDLE TN. NO ADDITIONAL UPDATES TO THE ZONES ARE NEEDED FOR NOW. THERE COULD STILL BE SOME PRE MIDNIGHT CONVECTION...BUT THE BULK OF THE ACTIVITY WILL BE AFTER MIDNIGHT. UPDATES TO COMMENCE WITH THE LIKELY INTRODUCTION OF CONVECTIVE WATCH BOXES LATER TONIGHT. PREV DISCUSSION... /ISSUED 614 PM CST TUE JAN 29 2013/ UPDATE...00Z AVIATION DISCUSSION. AVIATION...00Z AVIATION DISCUSSION. SFC PRESSURE GRADIENT WILL CONTINUE TO INCREASE AS APPROACHING COLD FRONTS MOVE INTO/ACROSS MID STATE DURING 30/12Z-30/24Z. ALSO...STRONG LOW LEVEL WIND SHEAR JUST OFF SFC WITH SLY WINDS 60KT-70KT EXPECTED THRU AROUND 30/12Z... WITH SOME SFC GUSTS TO AROUND 45KT EVEN POSSIBLE ALONG LEADING EDGE. A LINE OF STORMS...AT LEAST IN VCNTY OF COLD FRONTAL PASSAGE...AND MAY ALSO FORM OUT AHEAD...AS MOISTURE...INSTABILITY...AND LIFTING MECHANISMS COME INTO PLAY...AND THEN QUICKLY MOVE NEWD. EXPECT IMPACTS AT CKV AROUND 30/07Z... BNA 30/08Z...AND CSV 30/11Z. SOME HEAVY RAINFALL WILL ALSO ACCOMPANY THE STRONGER STORMS WITH SVR TSTMS POSSIBLY ALSO OUT AHEAD AND EMBEDDED IN LINE. TIMING AND DURATION OF THE LINE OF STORMS IS STILL UNCERTAIN...HOWEVER CKV/BNA CAN EXPECT THE STRONGEST STORMS TO MOVE OUT OF THE AREA BETWEEN 30/11-30/12Z. CSV MAY CONTINUE TO EXPERIENCE STRONGEST STORMS UNTIL AROUND 30/15Z. WINDS ARE STILL EXPECTED TO REMAIN AROUND 20 KTS WITH GUSTS TO 30 KTS FOR AREA THRU 30/24Z. CHANGE OVER TO ALL SHWRS IS EXPECTED W TO E DURING THE 30/18Z-30/24Z TOO. PREV DISCUSSION.../ISSUED 536 PM CST TUE JAN 29 2013/ UPDATE... MAIN FRONTAL BOUNDARY EXTENDS FROM CENTRAL MO SW THROUGH EASTERN OK. SEVERAL PRE FRONTAL BOUNDARIES IN ADVANCE OF THIS FEATURE WITH THE MAIN LINE OF CONVECTION CURRENTLY OVER NW AR. INSTABILITY AXIS WILL CONTINUE TO TRANSFER EASTWARD OVERNIGHT WITH THE MAIN LINE OF STORMS REACHING FAR WESTERN TN BETWEEN 03Z AND 07Z. IN ADVANCE OF THIS HOWEVER...CONVECTION STILL POSSIBLE AND WE ARE ALREADY SEEING SOME SHOWER AND TSTM ACTIVITY INTO PORTIONS OF EASTERN AR. GFS LOOKING A LITTLE FAST WITH THE MAIN LINE WHILE THE NAM MAY BE A LITTLE SLOW. BUT...THE MODELS ARE IN AGREEMENT WITH A VERY STRONG LINEAR OMEGA FIELD MATCHING UP WITH A POWERFUL 70-80 KT 850 MB JET. FURTHERMORE...SHOWALTERS AT OR JUST BELOW ZERO WILL ALIGN WITH AN IMPRESSIVE LOW TO MID LEVEL THETA-E AXIS TO HELP PROPEL THE CONVECTION. IN ADDITION TO THE SEVERE WEATHER THREAT...THE PRESSURE GRADIENT IS EXPECTED TO TIGHTEN UP BETWEEN NOW AND THROUGH 06Z. GOOD LOWER LEVEL SUBSIDENCE IS INDICATED AS THE WINDS ALOFT BEGIN TO STRENGTHEN. THUS...GUSTS TO 35 OR 40 MPH SHOULD BE EASY TO REACH OVERNIGHT. FOR THE UPDATE...WILL ATTEMPT TO ADJUST GRIDS SO AS TO INCREASE THE WIND SPEEDS IN THE ZONE TEXT. REMAINDER OF FCST IS IN GOOD SHAPE. THREAT OF STORMS DOES EXIST AHEAD OF THE MAIN LINE SO WILL LEAVE THE DAMAGE POTENTIAL IN PRIOR TO MIDNIGHT FOR NOW. UPDATE OUT SHORTLY. PREV DISCUSSION... /ISSUED 349 PM CST TUE JAN 29 2013/ DISCUSSION... THE FRONTAL PASSAGE AND ASSOCIATED SQUALL LINE WILL BE THE FOCUS OF THE FORECAST. LOW LEVEL WINDS ARE EXPECTED TO CONTINUE TO INCREASE AHEAD OF THE APPROACHING SYSTEM. A WIND ADVISORY CONTINUES FOR AREAS WEST OF THE PLATEAU UNTIL 6 PM WEDNESDAY...WHILE AREAS ALONG THE PLATEAU ARE UNDER A WIND ADVISORY STARTING AT 6 PM TONIGHT AND LASTING THROUGH 9 PM WEDNESDAY. SUSTAINED 25 MPH WINDS ARE POSSIBLE WITH GUSTS TO 45 MPH. PLENTY OF MOISTURE AND WARM AIR WILL CONTINUE TO SURGE INTO MIDDLE TN AHEAD OF THE SYSTEM. A FEW ISOLATED SHOWERS MAY BE POSSIBLE AHEAD OF THE LINE...BEFORE MIDNIGHT. HOWEVER THE MAIN THREAT REMAINS WITHIN AND AROUND THE EXPECTED SQUALL LINE...WITH THE MAIN CONCERNS BEING DAMAGING STRAIGHT LINE WINDS AND QLCS TORNADOES. THE ETA OF THE MAIN ACTIVITY WILL BE 11 PM TO 2 AM FOR AREAS NEAR THE TENNESSEE RIVER....1 AM TO 4 AM FOR AREAS ALONG THE I-65 CORRIDOR AND 4 AM TO 9 AM FOR AREAS ALONG AND NEAR THE CUMBERLAND PLATEAU. PWAT VALUES STILL REMAIN RELATIVELY HIGH FOR THIS TIME OF YEAR, HOWEVER DUE TO THE RATHER QUICK MOVEMENT OF THE STORM SYSTEM FLOODING DOES NOT APPEAR TO BE A MAJOR ISSUE. 1 TO 1.5 INCHES OF RAINFALL WILL BE POSSIBLE ACROSS THE AREA WITH LOCALLY HIGHER AMOUNTS WITHIN THE STRONGEST CELLS. BECAUSE THE GROUND WILL BE FAIRLY SATURATED EVEN SUB-SEVERE WIND GUSTS COULD CAUSE TREES TO TOPPLE OVER. THE MAIN LINE OF STORMS IS EXPECTED TO EXIT THE PLATEAU BY MID MORNING ON WEDNESDAY. SOME SHOWERS MAY LINGER AROUND THE MID STATE INTO THE AFTERNOON...AFTER THE DEPARTURE OF THE MAIN LINE OF STORMS...BUT BY LATE AFTERNOON THE WINDS WILL BEGIN TO SHIFT FROM SOUTHERLY TO WESTERLY...USHERING COLDER DRIER AIR INTO THE AREA FROM THE WEST. BY WEDNESDAY NIGHT PRECIPITATION WILL TAPER OFF WEST TO EAST...WITH A RAIN SNOW MIX TRANSITIONING TO LIGHT SNOW SHOWERS OR FLURRIES OVER THE PLATEAU AND HIGHER TERRAIN LATE. COLD AIR ADVECTION PEAKS WITH 850MB TEMPS DROPPING TO ABOUT -8C ON WEDNESDAY AS BROAD UPPER TROUGH OVER THE CONUS PERSISTS. EXPECT MARGINAL WARMING ON THURSDAY BEFORE A WEAK BUT QUICK MOVING SHORTWAVE ROTATES AROUND THE TROUGH THURSDAY NIGHT BRINGING THE POSSIBILITY OF LIGHT SNOWFALL TO THE AREA. LACK OF MOISTURE SHOULD KEEP ACCUMULATIONS DOWN...RANGING FROM A DUSTING TO A HALF INCH OVER THE LOWER ELEVATIONS...TO AROUND AN INCH OVER PORTIONS OF THE PLATEAU. THIS SYSTEM COULD STRENGTHEN OR WEAKEN WITH SUBSEQUENT MODEL RUNS...SO EXPECT CHANGES AS THE FORECAST TIME DRAWS NEAR. FOR FRIDAY...NORTHWESTERLY WINDS OF 5-10KTS ALONG WITH COLD AIR ADVECTION DROPPING 925MB TEMPS TO -8C TO -12C SHOULD MAKE FOR AN UNPLEASANT DAY. BUNDLE UP. BY THE WEEKEND...THE UPPER TROUGH LIFTS SLIGHTLY ALLOWING FOR A BIT OF WARMING...BUT ANOTHER WEAK SHORTWAVE ROTATES AROUND AND BRINGS PRECIPITATION BACK TO THE MID-STATE. THE WARMING SHOULD BE ENOUGH TO CHANGE EXPECTED PRECIP TO LIGHT RAIN SHOWERS...THOUGH A RAIN-SNOW MIX IS EXPECTED OVER THE HIGHER TERRAIN. LONG-RANGE MODELS INDICATE AN UPPER TROUGH WILL DEVELOP OVER THE CENTRAL STATES ALLOWING FOR A SOUTHERLY FLOW TO BRING WARM AND MOIST AIR BACK TO THE MID-STATE. AT THIS POINT ITS UNCERTAIN HOW MUCH WILL OCCUR...SO WILL LIMIT WEATHER TO CHANCE OF RAIN SHOWERS...AND WILL MONITOR MODEL UPDATES FOR THUNDERSTORM POTENTIAL. && .OHX WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 9 PM CST WEDNESDAY FOR TNZ011-032>034-065- 066-078>080. WIND ADVISORY UNTIL 6 PM CST WEDNESDAY FOR TNZ005>010-022>031- 056>064-075-077-093>095. && $$ 31
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1146 PM EST TUE JAN 29 2013 .SYNOPSIS... HIGH PRESSURE WILL BRING UNSEASONABLY WARM TEMPERATURES TO THE AREA WEDNESDAY. A STRONG COLD FRONT WILL MOVE THROUGH THE REGION LATE WEDNESDAY ACCOMPANIED BY SHOWERS WITH GUSTY WINDS AND HEAVY RAIN. MUCH COLDER TEMPERATURES WILL RETURN FOR THE END OF THE WEEK INTO THE WEEKEND AS HIGH PRESSURE MOVES SOUTHEAST FROM CANADA. && .NEAR TERM /THROUGH WEDNESDAY/... AS OF 955 PM EST TUESDAY... STARTING TO SEE SOME LIGHT REFLECTIVITY IN THE SOUTHWEST COUNTIES. EXPECT COVERAGE OF LIGHT RAIN TO EXPAND...ESPECIALLY AFTER MIDNIGHT IN THE FAVORED EASTERN UPSLOPE AREAS. HAVE INCREASED PROBABILITY OF PRECIPITATION ALONG THE SOUTHERN BLUE RIDGE IN LINE WITH LATEST WRF AND RAP GUIDANCE. BASED ON EXPECTED WINDS BY WEDNESDAY AFTERNOON...ESPECIALLY LOOKING AT THE 850 MB WINDS APPROACHING 60-65 KNOTS AND SUSTAINED WINDS ON THE DAN BUFKIT REACHING 20-25 MPH...HAVE EXPANDED THE WIND ADVISORY FOR THE REST OF THE COUNTY WARNING AREA. ALSO STRETCHED TIME OF HIGH WIND WARNING IN THE SOUTHWEST COUNTIES TO START AT 09Z. EXPECTING IT WILL NOT TAKE AS LONG AS 6AM TO START SEEING HIGH WINDS. AS OF 300 PM EST TUESDAY... ALL AREAS ARE EXPECTED TO BE CLOUDY BY EARLY WEDNESDAY MORNING. LIGHT PRECIPITATION WILL DEVELOP BY MIDNIGHT...PRIMARILY ALONG THE CREST OF THE BLUE RIDGE SOUTHWEST OF FLOYD VA INTO NW NC. AFTER MIDNIGHT...THE FOCUS FOR THE BEST CHANCE OF RAIN WILL STILL BE ALONG THE CREST OF THE BLUE RIDGE...HOWEVER...ALL PARTS OF THE FORECAST AREA WILL HAVE AT LEAST A SLIGHT CHANCE. AS WEDNESDAY PROGRESSES...PRECIPITATION CHANCES WILL PROGRESSIVELY INCREASE AS THE FRONT APPROACHES...AND THEN CROSSES THE AREA DURING THE AFTERNOON. TRENDS OF THE LATEST MODEL GUIDANCE ARE ABOUT THREE HOURS SLOWER WITH THE TIMING OF THE PASSAGE. AS SUCH...HAVE ADJUSTED OUR POP AND WEATHER GRIDS ACCORDINGLY. WHEN THE FRONT MOVES THROUGH THE AREA...WE ARE EXPECTING A STRONG SQUALL LINE OF SHOWERS WITH LIMITED...IF ANY...THUNDER. THERE IS A CONCERN THAT SOME OF THE STRONGER SHOWERS COULD HELP BRING HIGHER WINDS DOWN TO THE SURFACE...AND BE POTENTIALLY DAMAGING. OUR OTHER CONCERN FROM WIND INCLUDES GRADIENT PREVAILING WINDS IN ADVANCE OF THE FRONT. DURING THE AFTERNOON AND EARLY EVENING HOURS...WIND GUSTS AT THE HIGHER PEAKS ALONG AND WEST OF THE BLUE RIDGE...MAY SEE WIND GUSTS IN EXCESS OF WIND ADVISORY CRITERIA...40 KTS. WE ARE REFLECTING THIS CONCERN IN A WIND ADVISORY THAT WILL BE IN EFFECT FROM NOON WEDNESDAY THROUGH MIDNIGHT. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... AS OF 345 PM EST TUESDAY... FRONTAL PASSAGE WEDNESDAY EVENING WILL BRING DRAMATIC CHANGE IN TEMPERATURE...READINGS FALLING FROM THE 50S/60S WEDNESDAY EVENING INTO THE 20S/30S DURING THE OVERNIGHT. SLUG OF FRONTAL PRECIP WILL MOVE RAPIDLY EAST ACROSS THE CWA DURING THE EVENING WITH DOWNPOUR OF RAIN PRODUCING UPWARDS OF AN INCH OF RAIN IN LESS THAN 2 HOURS TIME. THIS BURST OF HEAVY RAINFALL WITH THE FRONTAL PASSAGE WILL LIKELY RESULT IN SUDDEN RISES TO AREA STREAMS. WILL FOREGO FLOOD WATCH ATTM PER QUICK MOVEMENT OF SYSTEM AND LACK OF SUSTAINED HEAVY RAIN THREAT. THAT SAID...STILL NOT A GOOD NIGHT TO BE FLIRTING AROUND LOW WATER CROSSINGS. FRONTAL PASSAGE HAS SLOWED A BIT COMPARED TO YESTERDAYS MODEL RUNS BY ABOUT 3 HOURS. LOOKS LIKE FROPA WILL OCCUR AT BLF/TNB BETWEEN 6-8PM...7-9PM AT BCB/ROA...AND 8-10PM AT LYH/DAN. AFTER FROPA...HEAVY RAIN THREAT WILL END...WINDS SHIFTING AROUND TO THE WEST-NORTHWEST...TEMPERATURES PLUMMETING BACK TO MORE OF A WINTER FLAVOR. ANY LINGERING MOISTURE IN THE MOUNTAINS WILL CHANGE TO SNOW SHOWERS OR FLURRIES...WITH A HALF INCH TO AN INCH OF ACCUMULATION POSSIBLE AT THE HIGHER ELEVATIONS LATE WEDNESDAY NIGHT AND EARLY THURSDAY. FOR THURSDAY AND INTO THE WEEKEND...COLD UPPER LEVEL TROUGH OF LOW PRESSURE WILL SET UP SHOP OVER THE EASTERN CONUS...ANY PRECIP PRODUCTION COMING FROM DISTURBANCES WITHIN THE NORTHERN STREAM. NEXT OPPORTUNITY FOR PRECIP FROM ONE OF THESE DISTURBANCES WILL COME THURSDAY NIGHT WITH A ROUND OF SNOW SHOWERS PASSING OVER THE MOUNTAINS AROUND MIDNIGHT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 305 PM EST TUESDAY... A LONG WAVE TROF REMAINS OVER THE EASTERN CONUS FOR THE WEEKEND. SFC HIGH CENTERED ALONG THE CAROLINA COAST SATURDAY WILL MOVE EAST INTO THE ATLANTIC OCEAN. A CLIPPER-LOW AND ATTENDING SURFACE COLD FRONT APPROACHES FROM THE WEST SATURDAY AND TRAVELS ACROSS FORECAST AREA SATURDAY NIGHT INTO SUNDAY MORNING. THE GFS SUGGEST THAT A COUPLE OF INCHES OF SNOW ACCUMULATION IS POSSIBLE IN THE WESTERN UPSLOPE AREAS. THE ECMWF HINTS AT LIGHTER SNOW TOTALS. KEPT SNOW SHOWERS IN THE NORTHWEST UPSLOPE FLOW FOR SUNDAY MORNING INTO SUNDAY AFTERNOON LEANING TOWARDS GFS THEN TAPER OFF AS THE TROF AXIS MOVES FURTHER INTO THE ATLANTIC. HIGH PRESSURE BUILDS ACROSS THE REGION SUNDAY NIGHT INTO MONDAY MORNING. ANOTHER LOW PRESSURE CENTER LIFTS NORTHEAST ACROSS GREAT LAKES AND PUSHES A COLD FRONT TOWARDS OUR REGION MONDAY. THE COLD FRONT ADVANCES ACROSS OUR REGION MONDAY NIGHT INTO TUESDAY. THE GFS DEVELOPS A LOW PRESSURE CENTER OFF THE VIRGINIA COAST MONDAY NIGHT AND LIFTS IT NORTHWARD ON TUESDAY. THE GFS SOLUTION INDICATED THAT MORE SNOW...SEVERAL INCHES ARE POSSIBLE IN THE WESTERN UPSLOPE AREAS ON MONDAY NIGHT INTO TUESDAY. WENT WITH SCATTERED POPS FOR MONDAY NIGHT INTO TUESDAY AND WILL WATCH FOR FURTHER RUNS TO SEE EVOLUTION AND DETAILS OF THIS STORM FOR EARLY NEXT WEEK. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... AS OF 1135 PM EST TUESDAY... CEILINGS WILL LOWER FROM SOUTHWEST TO NORTHEAST OVERNIGHT. EXPECTING MVFR CEILINGS AT ROA/LYH AND DAN BY 12Z. LIGHT RAIN ALONG THE BLUE RIDGE AND IN THE FOOTHILLS MAY OCCASIONALLY REDUCE THE VISIBILITY AT LOCAL AIRPORTS BEFORE 15Z. AN INTENSE COLD FRONT REACHES THE FORECAST AREA BY WEDNESDAY AFTERNOON. WINDS AHEAD OF THIS FRONT JUST ABOVE THE SURFACE WILL BE INCREASING ABOVE 50 KNOTS WHICH IS REFLECTED IN THE LLWS PART OF THE TAFS. BY AFTERNOON HIGH CONFIDENCE THERE WILL BE ENOUGH MIXING TO BRING WIND GUSTS DOWN TO THE SURFACE OF 30 TO 40 KNOTS. THE FRONT WILL PRODUCE A BROAD BAND OF SHOWERS AND POSSIBLY ISOLATED THUNDERSTORMS WITH HEAVY RAIN AND MVFR VISIBILITIES. MODELS AND BUFKIT SHOWED A SHARP WIND SHIFT TO THE WEST WITH THE FRONTAL PASSAGE. WINDS WILL STILL BE GUSTY BEHIND THE FRONT WEDNESDAY NIGHT. AS MUCH COLDER AIR ARRIVES BY THURSDAY...UPSLOPE SNOW SHOWERS WILL DEVELOP FOR KBLF AND KLWB...WITH CLEARING EAST OF THE BLUE RIDGE. NORTHWEST FLOW WILL PREVAIL FRIDAY THROUGH SUNDAY WITH POTENTIAL FOR TWO CLIPPER SYSTEMS TO BRING SNOW TO THE MOUNTAINS...ONE LATE THURSDAY NIGHT INTO FRIDAY AND THE NEXT SATURDAY INTO SUNDAY. && .HYDROLOGY... AN INCH /1.00/ TO AND INCH AND A HALF /1.50/ OF RAIN IS ANTICIPATED WITH THE FRONTAL PASSAGE WEDNESDAY EVENING. THE BULK OF THIS RAIN WILL BE ASSOCIATED WITH A SQUALL LINE OF SHOWERS ASSOCIATED WITH A FRONTAL PASSAGE...MOST OF THIS RAIN OCCURRING IN LESS THAN 2 HOURS. DUE TO THE SHORT DURATION OF THE HEAVY RAINFALL...EXPECT RAPID RISES ALONG AREA STREAMS. AS LONG AS THE RAINFALL AMOUNTS REMAIN BELOW 1.5 INCHES...FLOODING SHOULD BE KEPT TO A MINIMUM. ENSEMBLE FORECASTS SUGGEST THERE WILL ALSO BE SOME RESPECTABLE RISES ON THE AREA RIVERS. 1.50 INCHES OF RAIN WILL CAUSE RIVERS TO RISE TO NEAR BANKFULL. IF RAIN AMOUNTS EXCEED 1.50 INCHES OVER ANY GIVEN BASIN...THEN RIVER FLOODING WOULD BECOME AN ISSUE. ATTM...CURRENT FORECASTS REFLECT BASIN AVERAGE AMOUNTS CLOSER TO 1.25 INCHES. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WIND ADVISORY FROM NOON WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR VAZ011-013-014-016>020-022>024-032>035-043>047- 058-059. HIGH WIND WARNING FROM 4 AM WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR VAZ007-009-010-012-015. NC...WIND ADVISORY FROM NOON WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR NCZ002>006-019-020. HIGH WIND WARNING FROM 4 AM WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR NCZ001-018. WV...WIND ADVISORY FROM NOON WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR WVZ043>045. HIGH WIND WARNING FROM 4 AM WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR WVZ042. && $$ SYNOPSIS...AMS/RAB NEAR TERM...AMS/DS SHORT TERM...PM LONG TERM...KK AVIATION...AMS/KK HYDROLOGY...
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
303 AM CST WED JAN 30 2013 .SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT 303 AM CST TUE JAN 29 2013 303 AM UPDATE...30.00Z NAM...HIRES ARW...HIRES NMM AND 30.05Z HRRR ALL HAVE A GOOD HANDLE ON THE DEFORMATION AREA OF SNOW APPROACHING FROM IOWA. THE SNOW LOOKS TO SPREAD ACROSS MOST OF THE AREA EXCEPT FOR TAYLOR COUNTY BY 6 AM. IN ADDITION...THE MODELS FORECAST THAT THE OVERALL AREA OF SNOW HAS SHIFTED SLIGHTLY TO THE EAST. THIS REQUIRES SOME ADJUSTMENTS TO THE HAZARDS...DOWNGRADING SOME OF THE WARNINGS TO ADVISORIES AND REMOVING THE PREVIOUS ADVISORIES. PART OF THE PROBLEM TOO WITH REACHING THE WARNING CRITERIA IS THAT SNOW HAS REALLY HELD OFF MUCH OF THE CURRENT NIGHT TIME PERIOD THUS FAR...DUE TO DRY AIR IN PLACE SEEN ON THE 00Z MPX SOUNDING. IN ADDITION...THE FORCING WITH THE COMMA HEAD OF THE SHORTWAVE...CURRENTLY COMING UP THROUGH NORTHWEST MISSOURI...HAS TAKEN TIME TO REACH THE AREA. WATCH WARNING ADVISORY SEGMENT BELOW DENOTES THE ADJUSTMENTS TO THE HAZARDS. MORE INFORMATION ABOUT THE CURRENT SNOW EVENT WILL BE FORTHCOMING IN THE HOUR WITH THE REGULAR 4 AM ISSUANCE. PREVIOUS DISCUSSION ISSUED AT 303 PM CST TUE JAN 29 MAIN FORECAST FOCUS IS ON WINTER STORM TONIGHT AND WEDNESDAY WITH POTENTIAL MIXED PRECIPITATION AT ONSET AND THEN SNOW AMOUNTS AND BLOWING SNOW. ALSO WIND CHILL FOR WEDNESDAY NIGHT INTO THURSDAY MORNING. 18Z SURFACE ANALYSIS SHOWS COLD FRONT NOW PUSHING THROUGH SOUTHWEST WISCONSIN. TEMPERATURES AHEAD OF THE FRONT WERE IN THE MIDDLE 40S IN GRANT COUNTY AND THE UPPER 50S IN EXTREME NORTHERN ILLINOIS. MEANWHILE...BEHIND THE FRONT TEMPERATURES GAVE FALLEN INTO THE MIDDLE 30S. AREA RADAR SHOWING ANOTHER SURGE OF RAIN LIFTING NORTHWARD THROUGH EASTERN IOWA. 29.12Z DETERMINISTIC MODELS STILL SHOWING SOME DIFFERENCES. GFS/GEM AND THE 29.00Z ECMWF ALL SHOWING DEFORMATION BAND OF PRECIPITATION ACROSS THE FORECAST AREA...WHILE NAM APPEARS TO BE THE OUTLIER AND HAS SHIFTED THE BULK OF THE PRECIPITATION FURTHER SOUTH AND EAST. HAVE SIDED WITH THE MORE CONSISTENT NON NAM SOLUTIONS. FOR TONIGHT...COLD AIR SURGES INTO THE AREA BEHIND THE COLD FRONT...WHILE MOISTURE LIFTS NORTHWARD. THERMAL PROFILES SUGGEST MAINLY RAIN FOR SOUTHWEST WISCONSIN WITH A SWITCH OVER TO SNOW TOWARDS MIDNIGHT. THERE COULD BE A BRIEF PERIOD OF SLEET MIXED IN BEFORE THE CHANGE OVER OCCURS. WITH THE ALREADY SWOLLEN RIVERS FROM THE EARLIER RAINS AND ADDING ANOTHER .30 INCHES THIS EVENING WILL LIKELY SEE THE HYDRO PROBLEM CONTINUING AND WILL CONTINUE THE FLOOD WATCH FOR GRANT COUNTY. THE REMAINDER OF THE AREA WILL SEE ALL SNOW WITH THE ACCUMULATING SNOW BEGINNING AFTER 06Z. THE SNOW CONTINUES WEDNESDAY AS ANOTHER SHORTWAVE/SURFACE LOW LIFTS NORTHEAST ACROSS EASTERN IOWA INTO NORTHERN ILLINOIS. DEFORMATION BAND OF HEAVY SNOW WILL SET UP ACROSS THE SOUTHEAST HALF OF THE FORECAST AREA. SOUNDINGS SHOWING STRONG LIFT IN THE DENDRITIC GROWTH ZONE DURING THE MORNING HOURS. EXPECT SNOW RATIOS IN THE 15:1 TO 18:1 RANGE WHICH SHOULD RESULT INA BAND OF 6 TO 9 INCHES OF SNOW...WITH THE HIGHER AMOUNTS RUNNING FROM AROUND THE ADAMS/FRIENDSHIP TO CLAYTON COUNTY IOWA LINE. HAVE UPGRADED THE WATCH AREA TO WARNING...WITH A BORDERING WINTER WEATHER ADVISORY NORTH OF THE WARNING AREA. IN ADDITION...PRESSURE GRADIENT TIGHTENS AND WINDS LOOK TO GUST TO 20 TO 30 MPH WHICH WILL CREATE SOME BLOWING SNOW...ESPECIALLY ACROSS THE MORE OPEN AREAS. SNOW WILL TAPER OFF BY MID TO LATE AFTERNOON...BUT WIT THE WINDS CONTINUING WILL SEE TE BLOWING AND DRIFTING OF THE SNOW. ARCTIC AIR WILL CONTINUE TO SURGE INTO THE AREA WEDNESDAY NIGHT. PRESSURE GRADIENT REMAIN RATHER TIGHT AND WITH TEMPERATURES FALLING INTO THE SINGLE DIGITS ABOVE AND BELOW ZERO WILL SEE WIND CHILLS APPROACHING 20 BELOW OVER SOUTHEAST MINNESOTA AND NORTHEAST IOWA. ARCTIC HIGH THEN BUILDS SOUTHWARD THROUGH THE NORTHERN PLAINS THURSDAY. 850MB TEMPERATURES BOTTOM OUT IN THE 20 TO 25 BELOW ZERO RANGE CELSIUS AND WITH THE HIGH STILL OVER THE NORTHERN PLAINS...WINDS WILL CONTINUE TO BE A FACTOR. VERY LITTLE REBOUND EXPECTED IN THE AMBIENT TEMPERATURE WIND CHILLS WILL REMAIN IN THE 10 TO 20 BELOW ZERO RANGE. AS THE HIGH SLIPS SOUTH THE RIDGE AXIS DOES SHIFT ACROSS THE FORECAST AREA THURSDAY NIGHT. IF THIS OCCURS WILL LIKELY SEE SOMEWHAT LIGHTER WINDS AND GOOD RADIATIONAL COLLING CONDITIONS. ALONG WITH THIS A LIKELY FRESH SNOWPACK COULD SEE TEMPERATURES REALLY BOTTOM OUT IN THE TEENS BELOW ZERO. DID LOWER A FEW DEGREES FROM THE PREVIOUS FORECAST...BUT MAY NEED TO BE LOWERED MORE. GIVEN WINDS NOT GOING CALM WILL LIKELY NEED WIND CHILL ADVISORIES FOR MUCH OF THE AREA. .LONG TERM... 303 PM CST TUE JAN 29 2013 NORTHWEST FLOW CONTINUES ACROSS THE REGION THROUGH THE WEEKEND...WITH A SURFACE HIGH DRIFTING ACROSS THE AREA. ANOTHER SHORTWAVE LOOKS TO DROP THROUGH THE FLOW LATE SUNDAY NIGHT AND MONDAY AND COULD BRING SOME SNOW TO THE AREA. ECMWF FURTHER NORTH AFFECTING MAINLY NORTHERN AND EASTERN WISCONSIN. FOR NOW KEPT THE LOWER END PROBABILITIES ACROSS THE FAR NORTH. OTHERWISE...TEMPERATURES MODERATE SOMEWHAT AHEAD OF THIS SYSTEM TO SLIGHTLY ABOVE NORMAL...BUT THEN FALL BACK TO NEAR NORMAL ON TUESDAY. && .AVIATION...THROUGH 06Z THURSDAY 1105 PM CST TUE JAN 29 2013 THE SURFACE LOW HAS MOVED SLOWLY OUT OF NORTHWEST ARKANSAS INTO SOUTH CENTRAL MISSOURI THIS EVENING. THIS HAS RESULTED IN A SLOW NORTHWARD PUSH OF THE SNOW FROM SOUTHWEST IOWA INTO CENTRAL IOWA. THE 30.00Z NAM AND 30.02Z HRRR CONTINUE TO HAVE A GOOD HANDLE ON HOW THE PRECIPITATION HAS BEEN EVOLVING THIS EVENING WITH BOTH MODELS SUGGESTING THAT KLSE HAS A BETTER CHANCE OF GETTING INTO THE PRECIPITATION THAN KRST DOES. WITH THE NORTHEAST MOVEMENT OF THE SNOW...IT IS EXPECTED TO START MOVING INTO KLSE LATE TONIGHT AND KRST AROUND 12Z WITH VISIBILITIES GOING DOWN TO MVFR. AS THE MODERATE TO STRONG FRONTOGENESIS IN THE 750-500 MB LAYER COMES ACROSS WEDNESDAY MORNING...THE SNOW SHOULD INTENSIFY BUT WITH THE BEST ISENTROPIC UP GLIDE ON THE 290K SURFACE REMAINING SOUTHEAST OF BOTH TAF SITES...NOT EXPECTING THE HEAVIEST BAND OF SNOW TO IMPACT EITHER TAF SITE. BOTH SITES SHOULD STILL SEE IFR CONDITIONS BUT THE VISIBILITY SHOULD BE LOWER AT KLSE. KRST WILL SEE IMPROVEMENT STARTING ALREADY LATE WEDNESDAY MORNING AND IN THE EARLY AFTERNOON OR KLSE AS CONDITIONS GO BACK TO MVFR. SOME FLURRIES EXPECTED TO HANG ON DURING THE AFTERNOON WITH VFR VISIBILITY BUT LOOK FOR THE CEILINGS TO REMAIN MVFR FOR THE REMAINDER OF THE PERIOD. THE TIGHT GRADIENT AROUND THE SURFACE LOW WILL PRODUCE SUSTAINED NORTH TO NORTHWEST WINDS OF 15 TO 20 KNOTS WITH GUSTS OF 25 TO 30. THE NAM BUFKIT SOUNDINGS SUGGEST THE LOW LEVEL LAPSE RATES WILL REMAIN STEEP ENOUGH TO KEEP THE GUSTS GOING AFTER SUNSET WEDNESDAY EVENING. && .ARX WATCHES/WARNINGS/ADVISORIES... 303 AM CST WED JAN 30 2013 WI...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR WIZ029- 033-034-041. WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR WIZ042>044- 053>055-061. MN...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR MNZ088- 095-096. WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST THURSDAY FOR MNZ079-086-087-094-095. IA...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR IAZ009- 010-018-019. WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST THURSDAY FOR IAZ008-009-018-019. WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR IAZ011-029- 030. && $$ SHORT TERM...RABERDING/AJ LONG TERM...RABERDING AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1105 PM CST TUE JAN 29 2013 .SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT 303 PM CST TUE JAN 29 2013 MAIN FORECAST FOCUS IS ON WINTER STORM TONIGHT AND WEDNESDAY WITH POTENTIAL MIXED PRECIPITATION AT ONSET AND THEN SNOW AMOUNTS AND BLOWING SNOW. ALSO WIND CHILL FOR WEDNESDAY NIGHT INTO THURSDAY MORNING. 18Z SURFACE ANALYSIS SHOWS COLD FRONT NOW PUSHING THROUGH SOUTHWEST WISCONSIN. TEMPERATURES AHEAD OF THE FRONT WERE IN THE MIDDLE 40S IN GRANT COUNTY AND THE UPPER 50S IN EXTREME NORTHERN ILLINOIS. MEANWHILE...BEHIND THE FRONT TEMPERATURES GAVE FALLEN INTO THE MIDDLE 30S. AREA RADAR SHOWING ANOTHER SURGE OF RAIN LIFTING NORTHWARD THROUGH EASTERN IOWA. 29.12Z DETERMINISTIC MODELS STILL SHOWING SOME DIFFERENCES. GFS/GEM AND THE 29.00Z ECMWF ALL SHOWING DEFORMATION BAND OF PRECIPITATION ACROSS THE FORECAST AREA...WHILE NAM APPEARS TO BE THE OUTLIER AND HAS SHIFTED THE BULK OF THE PRECIPITATION FURTHER SOUTH AND EAST. HAVE SIDED WITH THE MORE CONSISTENT NON NAM SOLUTIONS. FOR TONIGHT...COLD AIR SURGES INTO THE AREA BEHIND THE COLD FRONT...WHILE MOISTURE LIFTS NORTHWARD. THERMAL PROFILES SUGGEST MAINLY RAIN FOR SOUTHWEST WISCONSIN WITH A SWITCH OVER TO SNOW TOWARDS MIDNIGHT. THERE COULD BE A BRIEF PERIOD OF SLEET MIXED IN BEFORE THE CHANGE OVER OCCURS. WITH THE ALREADY SWOLLEN RIVERS FROM THE EARLIER RAINS AND ADDING ANOTHER .30 INCHES THIS EVENING WILL LIKELY SEE THE HYDRO PROBLEM CONTINUING AND WILL CONTINUE THE FLOOD WATCH FOR GRANT COUNTY. THE REMAINDER OF THE AREA WILL SEE ALL SNOW WITH THE ACCUMULATING SNOW BEGINNING AFTER 06Z. THE SNOW CONTINUES WEDNESDAY AS ANOTHER SHORTWAVE/SURFACE LOW LIFTS NORTHEAST ACROSS EASTERN IOWA INTO NORTHERN ILLINOIS. DEFORMATION BAND OF HEAVY SNOW WILL SET UP ACROSS THE SOUTHEAST HALF OF THE FORECAST AREA. SOUNDINGS SHOWING STRONG LIFT IN THE DENDRITIC GROWTH ZONE DURING THE MORNING HOURS. EXPECT SNOW RATIOS IN THE 15:1 TO 18:1 RANGE WHICH SHOULD RESULT INA BAND OF 6 TO 9 INCHES OF SNOW...WITH THE HIGHER AMOUNTS RUNNING FROM AROUND THE ADAMS/FRIENDSHIP TO CLAYTON COUNTY IOWA LINE. HAVE UPGRADED THE WATCH AREA TO WARNING...WITH A BORDERING WINTER WEATHER ADVISORY NORTH OF THE WARNING AREA. IN ADDITION...PRESSURE GRADIENT TIGHTENS AND WINDS LOOK TO GUST TO 20 TO 30 MPH WHICH WILL CREATE SOME BLOWING SNOW...ESPECIALLY ACROSS THE MORE OPEN AREAS. SNOW WILL TAPER OFF BY MID TO LATE AFTERNOON...BUT WIT THE WINDS CONTINUING WILL SEE TE BLOWING AND DRIFTING OF THE SNOW. ARCTIC AIR WILL CONTINUE TO SURGE INTO THE AREA WEDNESDAY NIGHT. PRESSURE GRADIENT REMAIN RATHER TIGHT AND WITH TEMPERATURES FALLING INTO THE SINGLE DIGITS ABOVE AND BELOW ZERO WILL SEE WIND CHILLS APPROACHING 20 BELOW OVER SOUTHEAST MINNESOTA AND NORTHEAST IOWA. ARCTIC HIGH THEN BUILDS SOUTHWARD THROUGH THE NORTHERN PLAINS THURSDAY. 850MB TEMPERATURES BOTTOM OUT IN THE 20 TO 25 BELOW ZERO RANGE CELSIUS AND WITH THE HIGH STILL OVER THE NORTHERN PLAINS...WINDS WILL CONTINUE TO BE A FACTOR. VERY LITTLE REBOUND EXPECTED IN THE AMBIENT TEMPERATURE WIND CHILLS WILL REMAIN IN THE 10 TO 20 BELOW ZERO RANGE. AS THE HIGH SLIPS SOUTH THE RIDGE AXIS DOES SHIFT ACROSS THE FORECAST AREA THURSDAY NIGHT. IF THIS OCCURS WILL LIKELY SEE SOMEWHAT LIGHTER WINDS AND GOOD RADIATIONAL COLLING CONDITIONS. ALONG WITH THIS A LIKELY FRESH SNOWPACK COULD SEE TEMPERATURES REALLY BOTTOM OUT IN THE TEENS BELOW ZERO. DID LOWER A FEW DEGREES FROM THE PREVIOUS FORECAST...BUT MAY NEED TO BE LOWERED MORE. GIVEN WINDS NOT GOING CALM WILL LIKELY NEED WIND CHILL ADVISORIES FOR MUCH OF THE AREA. .LONG TERM... 303 PM CST TUE JAN 29 2013 NORTHWEST FLOW CONTINUES ACROSS THE REGION THROUGH THE WEEKEND...WITH A SURFACE HIGH DRIFTING ACROSS THE AREA. ANOTHER SHORTWAVE LOOKS TO DROP THROUGH THE FLOW LATE SUNDAY NIGHT AND MONDAY AND COULD BRING SOME SNOW TO THE AREA. ECMWF FURTHER NORTH AFFECTING MAINLY NORTHERN AND EASTERN WISCONSIN. FOR NOW KEPT THE LOWER END PROBABILITIES ACROSS THE FAR NORTH. OTHERWISE...TEMPERATURES MODERATE SOMEWHAT AHEAD OF THIS SYSTEM TO SLIGHTLY ABOVE NORMAL...BUT THEN FALL BACK TO NEAR NORMAL ON TUESDAY. && .AVIATION...THROUGH 06Z THURSDAY 1105 PM CST TUE JAN 29 2013 THE SURFACE LOW HAS MOVED SLOWLY OUT OF NORTHWEST ARKANSAS INTO SOUTH CENTRAL MISSOURI THIS EVENING. THIS HAS RESULTED IN A SLOW NORTHWARD PUSH OF THE SNOW FROM SOUTHWEST IOWA INTO CENTRAL IOWA. THE 30.00Z NAM AND 30.02Z HRRR CONTINUE TO HAVE A GOOD HANDLE ON HOW THE PRECIPITATION HAS BEEN EVOLVING THIS EVENING WITH BOTH MODELS SUGGESTING THAT KLSE HAS A BETTER CHANCE OF GETTING INTO THE PRECIPITATION THAN KRST DOES. WITH THE NORTHEAST MOVEMENT OF THE SNOW...IT IS EXPECTED TO START MOVING INTO KLSE LATE TONIGHT AND KRST AROUND 12Z WITH VISIBILITIES GOING DOWN TO MVFR. AS THE MODERATE TO STRONG FRONTOGENESIS IN THE 750-500 MB LAYER COMES ACROSS WEDNESDAY MORNING...THE SNOW SHOULD INTENSIFY BUT WITH THE BEST ISENTROPIC UP GLIDE ON THE 290K SURFACE REMAINING SOUTHEAST OF BOTH TAF SITES...NOT EXPECTING THE HEAVIEST BAND OF SNOW TO IMPACT EITHER TAF SITE. BOTH SITES SHOULD STILL SEE IFR CONDITIONS BUT THE VISIBILITY SHOULD BE LOWER AT KLSE. KRST WILL SEE IMPROVEMENT STARTING ALREADY LATE WEDNESDAY MORNING AND IN THE EARLY AFTERNOON OR KLSE AS CONDITIONS GO BACK TO MVFR. SOME FLURRIES EXPECTED TO HANG ON DURING THE AFTERNOON WITH VFR VISIBILITY BUT LOOK FOR THE CEILINGS TO REMAIN MVFR FOR THE REMAINDER OF THE PERIOD. THE TIGHT GRADIENT AROUND THE SURFACE LOW WILL PRODUCE SUSTAINED NORTH TO NORTHWEST WINDS OF 15 TO 20 KNOTS WITH GUSTS OF 25 TO 30. THE NAM BUFKIT SOUNDINGS SUGGEST THE LOW LEVEL LAPSE RATES WILL REMAIN STEEP ENOUGH TO KEEP THE GUSTS GOING AFTER SUNSET WEDNESDAY EVENING. && .ARX WATCHES/WARNINGS/ADVISORIES... 640 PM CST TUE JAN 29 2013 WI...WINTER STORM WARNING UNTIL 6 PM CST WEDNESDAY FOR WIZ033-034-041- 042-053. WINTER WEATHER ADVISORY UNTIL 6 PM CST WEDNESDAY FOR WIZ017-029- 032. WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST WEDNESDAY FOR WIZ043-044-054-055-061. MN...WINTER STORM WARNING UNTIL 6 PM CST WEDNESDAY FOR MNZ088-095-096. WINTER WEATHER ADVISORY UNTIL 6 PM CST WEDNESDAY FOR MNZ079-086- 087-094. IA...WINTER STORM WARNING UNTIL 6 PM CST WEDNESDAY FOR IAZ009>011-018- 019-029. WINTER WEATHER ADVISORY UNTIL 6 PM CST WEDNESDAY FOR IAZ008. WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST WEDNESDAY FOR IAZ030. && $$ SHORT TERM...RABERDING LONG TERM...RABERDING AVIATION...04
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
647 AM EST WED JAN 30 2013 .PREV DISCUSSION... /ISSUED 621 AM EST WED JAN 30 2013/ UPDATE... SECOND UPDATE TO INCLUDE EXPANDED TORNADO WATCH 17 AREA IN THE FFC WATCHES/WARNINGS/ADVISORIES SECTION BELOW. BELANGER PREV DISCUSSION... /ISSUED 410 AM EST WED JAN 30 2013/ SHORT TERM /TODAY THROUGH THURSDAY NIGHT/... PRIMARY CONCERN IS THREAT AND TIMING OF SEVERE CONVECTION THIS AFTERNOON AND EARLY EVENING. VERY IMPRESSIVE STORM SYSTEM APPROACHING THE STATE THIS MORNING. WHILE FAVORABLE SIG TOR PARAMETER VALUES CURRENTLY CONFINED TO AREA CLOSER TO THE COAST BASED ON RAP ANALYSES...HAVE SEEN A FEW REPORTS OF WIND DAMAGE FURTHER NORTH OVER WRN TN AND NRN MS IN LOW CAPE AREAS. IF MODELS ARE TO BE BELIEVED...PARAMETERS SHOULD BE MORE FAVORABLE HERE THAN WHAT IS CURRENTLY SHOWN TO THE WEST. 00Z MODELS HAVE SLOWED TIMING OF MAIN LINE OF TSRA SOMEWHAT WITH NAM SLOWEST. 06Z NAM ALSO CONTINUING SLOWER TREND. LINE SHOULD MOVE INTO NW CORNER OF CWA AROUND 10AM... I-85 BY 3PM AND AHN-MCN-AMERICUS LINE BY 7PM AND EXITING SE CORNER OF CWA AROUND 10PM. INGREDIENTS STILL APPEAR SUFFICIENT FOR AT LEAST ISOLD AREAS OF WIND DMG OR BRIEF TORNADOES. AS OFTEN THE CASE...06Z NAM MLCAPE SHOWING MORE INSTABILITY THAN OTHER MODELS WITH VALUES AROUND 400-700 J/KG. 00Z GFS HAS 200-400 J/KG OVER ALL BUT NE GA. VERTICAL WIND SHEAR WILL BE VERY STRONG. 0-1KM BULK SHEAR 40-50KTS SEEN ON GFS AND NAM. FAVORABLE CIN...LCL AND DEEP LAYER SHEAR YIELDING DECENT SIG TOR PARAMETER VALUES... 1-2 WITH GFS AND 2-5 ON NAM. THIS VALUES ARE HIGHER THAN PREV SVR EVENT ON DEC 26 WHEN WE SAW 3 WEAK TORNADOES IN MIDDLE GA. WINDS STILL SHOULD KEEP MOST OF AREA IN ADV CRITERIA TODAY AND THIS EVENING. HAVE EXTENDED WIND ADV TIL MIDNIGHT. HIGH WIND WARNING CRITERIA NOT QUITE BEING MET IN LATEST MODEL GRIDS...BUT VERY CLOSE. WITH WET SOILS DEVELOPING QUICKLY THIS AFTERNOON...HAVE CONTINUED WIND WARNING THRU 6PM...AFTER WHICH TIME LLJ WILL SHIFT EAST OF THE NE GA MOUNTAINS. HEAVY RAIN WILL ALSO BE SIGNIFICANT THREAT. AGREE WITH LATEST HPC GUIDANCE WHICH HAS BUMPED UP EVENT TOTAL PRECIP TO 1 TO 2 INCHES WITH SOME AREAS OF NE GA APPROACHING 2.5 INCHES...DUE TO SLOWER TIMING AND PROGRESSION OF TSRA. SFC DEWPOINTS HAVE BEEN HIGHER THAN FCST LAST SEVERAL HOURS AS WELL. BASED ON LATEST GRIDDED FFG AND QPF...HAVE EXPANDED FLOOD WATCH SOUTH TO AREAS NORTH OF A FRANKLIN TO ROSWELL TO CLEVELAND LINE. FINALLY...ANOTHER LOW AMPLITUDE SHORT WAVE PROGGED TO MOVE ALONG LONG WAVE TROUGH OVER TN VALLEY THURS NIGHT. WITH COLD AIR IN PLACE...ESP ALOFT...COULD SEE SOME FLURRIES OR VERY LIGHT SNOW SHOWERS. NO IMPACTS EXPECTED. SNELSON LONG TERM /FRIDAY THROUGH TUESDAY/... EXTENDED MODELS IN FAIRLY GOOD AGREEMENT THROUGH THE LONG TERM...WITH LONG WAVE UPPER-LEVEL TROUGH SITUATED OVER THE EASTERN U.S. THOUGH EARLY NEXT WEEK. GENERALLY...NORTHWEST FLOW WILL PERSIST OVER THE REGION...AND MODELS CONTINUE TO ADVERTISE A SERIES OF UPPER LEVEL SHORT WAVES IMPACTING THE AREA AS A RESULT. THE FIRST DISTURBANCE OCCURS AT THE TAIL END OF THE SHORT TERM PERIODS...AND WHAT MOISTURE QUICKLY DISSIPATES INTO THE LONG TERM EARLY FRIDAY. THE SECOND DISTURBANCE LOOKS TO APPROACH THE AREA LATE SATURDAY AND REMAIN ACROSS FAR NORTH GEORGIA EARLY SUNDAY...WITH SLIGHTLY MORE MOISTURE AVAILABLE THAN THE PREVIOUS SHORTWAVE. FOR NOW...WITH THE LATEST MODEL TIMING FOR THIS SYSTEM...LOOKS LIKE IT WILL PRIMARILY BE RAIN...WITH SOME POSSIBILITY OF A RAIN-SNOW MIX INTO SUNDAY MORNING. HAVE GENERALLY GONE WITH SLIGHT CHANCE POPS...AND HAVE KEPT NO ACCUMULATIONS FOR NORTH GEORGIA. HAVE SCALED BACK POPS SLIGHTLY FOR THE THIRD SHORT WAVE EXPECTED MONDAY NIGHT INTO TUESDAY. LATEST MODEL RUNS ARE LESS ENTHUSIASTIC WITH THE FRONTAL SUPPORT...AND THEREFORE LESS AGGRESSIVE WITH MOISTURE AND PRECIP POTENTIAL. HAVE CONTINUED WITH SLIGHT CHANCE POPS MONDAY NIGHT AND TUESDAY...AND QUICKLY DROP POPS OFF INTO TUESDAY NIGHT. BELANGER FIRE WEATHER... AS DRY AIR PLUNGES IN BEHIND FRONT...HUMIDITY PROGGED TO DROP TO 22 TO 25 PCT FOR A FEW HOURS THURS AFTERNOON OVER MIDDLE GA. WITH 1 TO 2 INCHES OF RAIN EXPECTED TODAY...FUELS ARE EXPECTED TO BE TOO WET TO REQUIRE ANY FIRE DANGER STATEMENTS. SNELSON && .AVIATION... 12Z UPDATE... STILL MONITORING LINE OF STRONG TSRA THAT WILL MOVE ACROSS THE STATE TODAY AND THIS EVENING. TIMING HAS SHIFTED SLIGHTLY AND NOW APPEARS TSRA WILL AFFECT ATL METRO 19Z-23Z. EXPECT STRONG CROSSWIND AT E-W RUNWAY AIRPORTS TODAY...GUSTS COULD APPROACH 32KTS AT KATL. CIGS SHOULD STAY RIGHT NEAR IFR THRESHOLD AT KATL AND REMAIN JUST ABOVE IFR ELSEWHERE. EXPECT END TO CIGS AND PRECIP AROUND 23-00Z. STRONG WEST WINDS WILL CONTINUE OVERNIGHT AND THURS. //ATL CONFIDENCE...12Z UPDATE... MEDIUM CONFIDENCE ON IFR CIGS THIS MORNING. HIGH CONFIDENCE ON ALL OTHER ELEMENTS. SNELSON && .PRELIMINARY POINT TEMPS/POPS... ATHENS 71 38 50 33 / 100 100 5 5 ATLANTA 67 35 49 33 / 100 60 5 5 BLAIRSVILLE 61 32 43 27 / 100 60 5 20 CARTERSVILLE 67 34 47 31 / 100 40 5 10 COLUMBUS 72 38 56 39 / 100 70 5 5 GAINESVILLE 63 35 47 32 / 100 70 5 10 MACON 73 39 55 33 / 90 100 5 5 ROME 68 33 48 31 / 100 40 5 10 PEACHTREE CITY 68 36 51 32 / 100 60 5 5 VIDALIA 80 46 59 36 / 70 90 0 5 && .FFC WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR THE FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BARTOW...BIBB...BLECKLEY... BUTTS...CARROLL...CATOOSA...CHATTAHOOCHEE...CHATTOOGA... CHEROKEE...CLARKE...CLAYTON...COBB...COWETA...CRAWFORD...CRISP... DADE...DEKALB...DODGE...DOOLY...DOUGLAS...EMANUEL...FAYETTE... FLOYD...FORSYTH...GLASCOCK...GORDON...GREENE...GWINNETT...HALL... HANCOCK...HARALSON...HARRIS...HEARD...HENRY...HOUSTON... JACKSON...JASPER...JEFFERSON...JOHNSON...JONES...LAMAR... LAURENS...MACON...MADISON...MARION...MERIWETHER...MONROE... MONTGOMERY...MORGAN...MUSCOGEE...NEWTON...NORTH FULTON... OCONEE...OGLETHORPE...PAULDING...PEACH...PIKE...POLK...PULASKI... PUTNAM...ROCKDALE...SCHLEY...SOUTH FULTON...SPALDING...STEWART... SUMTER...TALBOT...TALIAFERRO...TAYLOR...TELFAIR...TOOMBS... TREUTLEN...TROUP...TWIGGS...UPSON...WALKER...WALTON...WARREN... WASHINGTON...WEBSTER...WHEELER...WHITFIELD...WILCOX...WILKES... WILKINSON. HIGH WIND WARNING UNTIL 6 PM EST THIS EVENING FOR THE FOLLOWING ZONES: DAWSON...FANNIN...GILMER...LUMPKIN...MURRAY...PICKENS... TOWNS...UNION...WHITE. FLOOD WATCH THROUGH THIS EVENING FOR THE FOLLOWING ZONES: BARTOW...CATOOSA...CHATTOOGA...CHEROKEE...COBB...DADE...DAWSON... FANNIN...FLOYD...FORSYTH...GILMER...GORDON...HARALSON... LUMPKIN...MURRAY...NORTH FULTON...PAULDING...PICKENS...POLK... TOWNS...UNION...WALKER...WHITE...WHITFIELD. WIND ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT EST TONIGHT FOR THE FOLLOWING ZONES: DAWSON...FANNIN...GILMER...LUMPKIN... MURRAY...PICKENS...TOWNS...UNION...WHITE. TORNADO WATCH UNTIL 1 PM EST THIS AFTERNOON FOR THE FOLLOWING ZONES: BARTOW...CARROLL...CATOOSA...CHATTOOGA...DADE...FLOYD... GORDON...HARALSON...HEARD...MURRAY...PAULDING...POLK...WALKER... WHITFIELD. && $$ SHORT TERM...SNELSON LONG TERM....31 AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
621 AM EST WED JAN 30 2013 .UPDATE... SECOND UPDATE TO INCLUDE EXPANDED TORNADO WATCH 17 AREA IN THE FFC WATCHES/WARNINGS/ADVISORIES SECTION BELOW. BELANGER && PREV DISCUSSION... /ISSUED 410 AM EST WED JAN 30 2013/ SHORT TERM /TODAY THROUGH THURSDAY NIGHT/... PRIMARY CONCERN IS THREAT AND TIMING OF SEVERE CONVECTION THIS AFTERNOON AND EARLY EVENING. VERY IMPRESSIVE STORM SYSTEM APPROACHING THE STATE THIS MORNING. WHILE FAVORABLE SIG TOR PARAMETER VALUES CURRENTLY CONFINED TO AREA CLOSER TO THE COAST BASED ON RAP ANALYSES...HAVE SEEN A FEW REPORTS OF WIND DAMAGE FURTHER NORTH OVER WRN TN AND NRN MS IN LOW CAPE AREAS. IF MODELS ARE TO BE BELIEVED...PARAMETERS SHOULD BE MORE FAVORABLE HERE THAN WHAT IS CURRENTLY SHOWN TO THE WEST. 00Z MODELS HAVE SLOWED TIMING OF MAIN LINE OF TSRA SOMEWHAT WITH NAM SLOWEST. 06Z NAM ALSO CONTINUING SLOWER TREND. LINE SHOULD MOVE INTO NW CORNER OF CWA AROUND 10AM... I-85 BY 3PM AND AHN-MCN-AMERICUS LINE BY 7PM AND EXITING SE CORNER OF CWA AROUND 10PM. INGREDIENTS STILL APPEAR SUFFICIENT FOR AT LEAST ISOLD AREAS OF WIND DMG OR BRIEF TORNADOES. AS OFTEN THE CASE...06Z NAM MLCAPE SHOWING MORE INSTABILITY THAN OTHER MODELS WITH VALUES AROUND 400-700 J/KG. 00Z GFS HAS 200-400 J/KG OVER ALL BUT NE GA. VERTICAL WIND SHEAR WILL BE VERY STRONG. 0-1KM BULK SHEAR 40-50KTS SEEN ON GFS AND NAM. FAVORABLE CIN...LCL AND DEEP LAYER SHEAR YIELDING DECENT SIG TOR PARAMETER VALUES...1-2 WITH GFS AND 2-5 ON NAM. THIS VALUES ARE HIGHER THAN PREV SVR EVENT ON DEC 26 WHEN WE SAW 3 WEAK TORNADOES IN MIDDLE GA. WINDS STILL SHOULD KEEP MOST OF AREA IN ADV CRITERIA TODAY AND THIS EVENING. HAVE EXTENDED WIND ADV TIL MIDNIGHT. HIGH WIND WARNING CRITERIA NOT QUITE BEING MET IN LATEST MODEL GRIDS...BUT VERY CLOSE. WITH WET SOILS DEVELOPING QUICKLY THIS AFTERNOON...HAVE CONTINUED WIND WARNING THRU 6PM...AFTER WHICH TIME LLJ WILL SHIFT EAST OF THE NE GA MOUNTAINS. HEAVY RAIN WILL ALSO BE SIGNIFICANT THREAT. AGREE WITH LATEST HPC GUIDANCE WHICH HAS BUMPED UP EVENT TOTAL PRECIP TO 1 TO 2 INCHES WITH SOME AREAS OF NE GA APPROACHING 2.5 INCHES...DUE TO SLOWER TIMING AND PROGRESSION OF TSRA. SFC DEWPOINTS HAVE BEEN HIGHER THAN FCST LAST SEVERAL HOURS AS WELL. BASED ON LATEST GRIDDED FFG AND QPF...HAVE EXPANDED FLOOD WATCH SOUTH TO AREAS NORTH OF A FRANKLIN TO ROSWELL TO CLEVELAND LINE. FINALLY...ANOTHER LOW AMPLITUDE SHORT WAVE PROGGED TO MOVE ALONG LONG WAVE TROUGH OVER TN VALLEY THURS NIGHT. WITH COLD AIR IN PLACE...ESP ALOFT...COULD SEE SOME FLURRIES OR VERY LIGHT SNOW SHOWERS. NO IMPACTS EXPECTED. SNELSON LONG TERM /FRIDAY THROUGH TUESDAY/... EXTENDED MODELS IN FAIRLY GOOD AGREEMENT THROUGH THE LONG TERM...WITH LONG WAVE UPPER-LEVEL TROUGH SITUATED OVER THE EASTERN U.S. THOUGH EARLY NEXT WEEK. GENERALLY...NORTHWEST FLOW WILL PERSIST OVER THE REGION...AND MODELS CONTINUE TO ADVERTISE A SERIES OF UPPER LEVEL SHORT WAVES IMPACTING THE AREA AS A RESULT. THE FIRST DISTURBANCE OCCURS AT THE TAIL END OF THE SHORT TERM PERIODS...AND WHAT MOISTURE QUICKLY DISSIPATES INTO THE LONG TERM EARLY FRIDAY. THE SECOND DISTURBANCE LOOKS TO APPROACH THE AREA LATE SATURDAY AND REMAIN ACROSS FAR NORTH GEORGIA EARLY SUNDAY...WITH SLIGHTLY MORE MOISTURE AVAILABLE THAN THE PREVIOUS SHORTWAVE. FOR NOW...WITH THE LATEST MODEL TIMING FOR THIS SYSTEM...LOOKS LIKE IT WILL PRIMARILY BE RAIN...WITH SOME POSSIBILITY OF A RAIN-SNOW MIX INTO SUNDAY MORNING. HAVE GENERALLY GONE WITH SLIGHT CHANCE POPS...AND HAVE KEPT NO ACCUMULATIONS FOR NORTH GEORGIA. HAVE SCALED BACK POPS SLIGHTLY FOR THE THIRD SHORT WAVE EXPECTED MONDAY NIGHT INTO TUESDAY. LATEST MODEL RUNS ARE LESS ENTHUSIASTIC WITH THE FRONTAL SUPPORT...AND THEREFORE LESS AGGRESSIVE WITH MOISTURE AND PRECIP POTENTIAL. HAVE CONTINUED WITH SLIGHT CHANCE POPS MONDAY NIGHT AND TUESDAY...AND QUICKLY DROP POPS OFF INTO TUESDAY NIGHT. BELANGER FIRE WEATHER... AS DRY AIR PLUNGES IN BEHIND FRONT...HUMIDITY PROGGED TO DROP TO 22 TO 25 PCT FOR A FEW HOURS THURS AFTERNOON OVER MIDDLE GA. WITH 1 TO 2 INCHES OF RAIN EXPECTED TODAY...FUELS ARE EXPECTED TO BE TOO WET TO REQUIRE ANY FIRE DANGER STATEMENTS. SNELSON AVIATION... 06Z UPDATE... MAIN CONCERN IS TIMING OF TSRA THIS AFTERNOON. WELL DEFINED LINE OF TSRA WILL MOVE THRU FROM WEST TO EAST...IMPACTING ATL METRO AIRPORTS AROUND 18Z-22Z. SHOULD SEE WIDESPREAD -SHRA DEVELOPING A FEW HOURS BEFORE THEN AND POSSIBLY CONTINUING AFTER LINE OF TSRA HAS MOVED THRU. OTHER CONCERN TODAY IS STRONG CROSSWINDS AT AIRPORTS WITH E-W RUNWAY CONFIGURATION...INCLUDING KATL WHERE CROSSWIND COMPONENT GUSTS 16Z-22Z COULD APPROACH 30KTS. IFR CIGS LIKELY AT MOST AIRPORTS FROM 09Z THRU 14Z THOUGH MAY BE TOO WARM OVER MIDDLE GA AIRPORTS FOR CIGS TO GET DOWN TO IFR. CIGS WILL IMPROVE AFTER LINE OF TSRA MOVES THRU...AROUND 22Z AT ATL...THEN CLEAR ENTIRELY AFTER 06Z-09Z THURS. //ATL CONFIDENCE...06Z UPDATE... MEDIUM CONFIDENCE ON IFR CIGS THIS MORNING AND TSRA TIMING. HIGH CONFIDENCE ON ALL OTHER ELEMENTS. SNELSON && .PRELIMINARY POINT TEMPS/POPS... ATHENS 71 38 50 33 / 100 100 5 5 ATLANTA 67 35 49 33 / 100 60 5 5 BLAIRSVILLE 61 32 43 27 / 100 60 5 20 CARTERSVILLE 67 34 47 31 / 100 40 5 10 COLUMBUS 72 38 56 39 / 100 70 5 5 GAINESVILLE 63 35 47 32 / 100 70 5 10 MACON 73 39 55 33 / 90 100 5 5 ROME 68 33 48 31 / 100 40 5 10 PEACHTREE CITY 68 36 51 32 / 100 60 5 5 VIDALIA 80 46 59 36 / 70 90 0 5 && .FFC WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR THE FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BARTOW...BIBB...BLECKLEY... BUTTS...CARROLL...CATOOSA...CHATTAHOOCHEE...CHATTOOGA... CHEROKEE...CLARKE...CLAYTON...COBB...COWETA...CRAWFORD...CRISP... DADE...DEKALB...DODGE...DOOLY...DOUGLAS...EMANUEL...FAYETTE... FLOYD...FORSYTH...GLASCOCK...GORDON...GREENE...GWINNETT...HALL... HANCOCK...HARALSON...HARRIS...HEARD...HENRY...HOUSTON... JACKSON...JASPER...JEFFERSON...JOHNSON...JONES...LAMAR... LAURENS...MACON...MADISON...MARION...MERIWETHER...MONROE... MONTGOMERY...MORGAN...MUSCOGEE...NEWTON...NORTH FULTON... OCONEE...OGLETHORPE...PAULDING...PEACH...PIKE...POLK...PULASKI... PUTNAM...ROCKDALE...SCHLEY...SOUTH FULTON...SPALDING...STEWART... SUMTER...TALBOT...TALIAFERRO...TAYLOR...TELFAIR...TOOMBS... TREUTLEN...TROUP...TWIGGS...UPSON...WALKER...WALTON...WARREN... WASHINGTON...WEBSTER...WHEELER...WHITFIELD...WILCOX...WILKES... WILKINSON. HIGH WIND WARNING UNTIL 6 PM EST THIS EVENING FOR THE FOLLOWING ZONES: DAWSON...FANNIN...GILMER...LUMPKIN...MURRAY...PICKENS... TOWNS...UNION...WHITE. FLOOD WATCH THROUGH THIS EVENING FOR THE FOLLOWING ZONES: BARTOW...CATOOSA...CHATTOOGA...CHEROKEE...COBB...DADE...DAWSON... FANNIN...FLOYD...FORSYTH...GILMER...GORDON...HARALSON... LUMPKIN...MURRAY...NORTH FULTON...PAULDING...PICKENS...POLK... TOWNS...UNION...WALKER...WHITE...WHITFIELD. WIND ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT EST TONIGHT FOR THE FOLLOWING ZONES: DAWSON...FANNIN...GILMER...LUMPKIN... MURRAY...PICKENS...TOWNS...UNION...WHITE. TORNADO WATCH UNTIL 1 PM EST THIS AFTERNOON FOR THE FOLLOWING ZONES: BARTOW...CARROLL...CATOOSA...CHATTOOGA...DADE...FLOYD... GORDON...HARALSON...HEARD...MURRAY...PAULDING...POLK...WALKER... WHITFIELD. && $$ SHORT TERM...SNELSON LONG TERM....31 AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
555 AM EST WED JAN 30 2013 .UPDATE... UPDATE TO INCLUDE TORNADO WATCH 17 AREA IN THE FFC WATCHES/WARNINGS/ADVISORIES SECTION BELOW. BELANGER && .PREV DISCUSSION... /ISSUED 410 AM EST WED JAN 30 2013/ SHORT TERM /TODAY THROUGH THURSDAY NIGHT/... PRIMARY CONCERN IS THREAT AND TIMING OF SEVERE CONVECTION THIS AFTERNOON AND EARLY EVENING. VERY IMPRESSIVE STORM SYSTEM APPROACHING THE STATE THIS MORNING. WHILE FAVORABLE SIG TOR PARAMETER VALUES CURRENTLY CONFINED TO AREA CLOSER TO THE COAST BASED ON RAP ANALYSES...HAVE SEEN A FEW REPORTS OF WIND DAMAGE FURTHER NORTH OVER WRN TN AND NRN MS IN LOW CAPE AREAS. IF MODELS ARE TO BE BELIEVED...PARAMETERS SHOULD BE MORE FAVORABLE HERE THAN WHAT IS CURRENTLY SHOWN TO THE WEST. 00Z MODELS HAVE SLOWED TIMING OF MAIN LINE OF TSRA SOMEWHAT WITH NAM SLOWEST. 06Z NAM ALSO CONTINUING SLOWER TREND. LINE SHOULD MOVE INTO NW CORNER OF CWA AROUND 10AM... I-85 BY 3PM AND AHN-MCN-AMERICUS LINE BY 7PM AND EXITING SE CORNER OF CWA AROUND 10PM. INGREDIENTS STILL APPEAR SUFFICIENT FOR AT LEAST ISOLD AREAS OF WIND DMG OR BRIEF TORNADOES. AS OFTEN THE CASE...06Z NAM MLCAPE SHOWING MORE INSTABILITY THAN OTHER MODELS WITH VALUES AROUND 400-700 J/KG. 00Z GFS HAS 200-400 J/KG OVER ALL BUT NE GA. VERTICAL WIND SHEAR WILL BE VERY STRONG. 0-1KM BULK SHEAR 40-50KTS SEEN ON GFS AND NAM. FAVORABLE CIN...LCL AND DEEP LAYER SHEAR YIELDING DECENT SIG TOR PARAMETER VALUES...1-2 WITH GFS AND 2-5 ON NAM. THIS VALUES ARE HIGHER THAN PREV SVR EVENT ON DEC 26 WHEN WE SAW 3 WEAK TORNADOES IN MIDDLE GA. WINDS STILL SHOULD KEEP MOST OF AREA IN ADV CRITERIA TODAY AND THIS EVENING. HAVE EXTENDED WIND ADV TIL MIDNIGHT. HIGH WIND WARNING CRITERIA NOT QUITE BEING MET IN LATEST MODEL GRIDS...BUT VERY CLOSE. WITH WET SOILS DEVELOPING QUICKLY THIS AFTERNOON...HAVE CONTINUED WIND WARNING THRU 6PM...AFTER WHICH TIME LLJ WILL SHIFT EAST OF THE NE GA MOUNTAINS. HEAVY RAIN WILL ALSO BE SIGNIFICANT THREAT. AGREE WITH LATEST HPC GUIDANCE WHICH HAS BUMPED UP EVENT TOTAL PRECIP TO 1 TO 2 INCHES WITH SOME AREAS OF NE GA APPROACHING 2.5 INCHES...DUE TO SLOWER TIMING AND PROGRESSION OF TSRA. SFC DEWPOINTS HAVE BEEN HIGHER THAN FCST LAST SEVERAL HOURS AS WELL. BASED ON LATEST GRIDDED FFG AND QPF...HAVE EXPANDED FLOOD WATCH SOUTH TO AREAS NORTH OF A FRANKLIN TO ROSWELL TO CLEVELAND LINE. FINALLY...ANOTHER LOW AMPLITUDE SHORT WAVE PROGGED TO MOVE ALONG LONG WAVE TROUGH OVER TN VALLEY THURS NIGHT. WITH COLD AIR IN PLACE...ESP ALOFT...COULD SEE SOME FLURRIES OR VERY LIGHT SNOW SHOWERS. NO IMPACTS EXPECTED. SNELSON LONG TERM /FRIDAY THROUGH TUESDAY/... EXTENDED MODELS IN FAIRLY GOOD AGREEMENT THROUGH THE LONG TERM...WITH LONG WAVE UPPER-LEVEL TROUGH SITUATED OVER THE EASTERN U.S. THOUGH EARLY NEXT WEEK. GENERALLY...NORTHWEST FLOW WILL PERSIST OVER THE REGION...AND MODELS CONTINUE TO ADVERTISE A SERIES OF UPPER LEVEL SHORT WAVES IMPACTING THE AREA AS A RESULT. THE FIRST DISTURBANCE OCCURS AT THE TAIL END OF THE SHORT TERM PERIODS...AND WHAT MOISTURE QUICKLY DISSIPATES INTO THE LONG TERM EARLY FRIDAY. THE SECOND DISTURBANCE LOOKS TO APPROACH THE AREA LATE SATURDAY AND REMAIN ACROSS FAR NORTH GEORGIA EARLY SUNDAY...WITH SLIGHTLY MORE MOISTURE AVAILABLE THAN THE PREVIOUS SHORTWAVE. FOR NOW...WITH THE LATEST MODEL TIMING FOR THIS SYSTEM...LOOKS LIKE IT WILL PRIMARILY BE RAIN...WITH SOME POSSIBILITY OF A RAIN-SNOW MIX INTO SUNDAY MORNING. HAVE GENERALLY GONE WITH SLIGHT CHANCE POPS...AND HAVE KEPT NO ACCUMULATIONS FOR NORTH GEORGIA. HAVE SCALED BACK POPS SLIGHTLY FOR THE THIRD SHORT WAVE EXPECTED MONDAY NIGHT INTO TUESDAY. LATEST MODEL RUNS ARE LESS ENTHUSIASTIC WITH THE FRONTAL SUPPORT...AND THEREFORE LESS AGGRESSIVE WITH MOISTURE AND PRECIP POTENTIAL. HAVE CONTINUED WITH SLIGHT CHANCE POPS MONDAY NIGHT AND TUESDAY...AND QUICKLY DROP POPS OFF INTO TUESDAY NIGHT. BELANGER FIRE WEATHER... AS DRY AIR PLUNGES IN BEHIND FRONT...HUMIDITY PROGGED TO DROP TO 22 TO 25 PCT FOR A FEW HOURS THURS AFTERNOON OVER MIDDLE GA. WITH 1 TO 2 INCHES OF RAIN EXPECTED TODAY...FUELS ARE EXPECTED TO BE TOO WET TO REQUIRE ANY FIRE DANGER STATEMENTS. SNELSON AVIATION... 06Z UPDATE... MAIN CONCERN IS TIMING OF TSRA THIS AFTERNOON. WELL DEFINED LINE OF TSRA WILL MOVE THRU FROM WEST TO EAST...IMPACTING ATL METRO AIRPORTS AROUND 18Z-22Z. SHOULD SEE WIDESPREAD -SHRA DEVELOPING A FEW HOURS BEFORE THEN AND POSSIBLY CONTINUING AFTER LINE OF TSRA HAS MOVED THRU. OTHER CONCERN TODAY IS STRONG CROSSWINDS AT AIRPORTS WITH E-W RUNWAY CONFIGURATION...INCLUDING KATL WHERE CROSSWIND COMPONENT GUSTS 16Z-22Z COULD APPROACH 30KTS. IFR CIGS LIKELY AT MOST AIRPORTS FROM 09Z THRU 14Z THOUGH MAY BE TOO WARM OVER MIDDLE GA AIRPORTS FOR CIGS TO GET DOWN TO IFR. CIGS WILL IMPROVE AFTER LINE OF TSRA MOVES THRU...AROUND 22Z AT ATL...THEN CLEAR ENTIRELY AFTER 06Z-09Z THURS. //ATL CONFIDENCE...06Z UPDATE... MEDIUM CONFIDENCE ON IFR CIGS THIS MORNING AND TSRA TIMING. HIGH CONFIDENCE ON ALL OTHER ELEMENTS. SNELSON && .PRELIMINARY POINT TEMPS/POPS... ATHENS 71 38 50 33 / 100 100 5 5 ATLANTA 67 35 49 33 / 100 60 5 5 BLAIRSVILLE 61 32 43 27 / 100 60 5 20 CARTERSVILLE 67 34 47 31 / 100 40 5 10 COLUMBUS 72 38 56 39 / 100 70 5 5 GAINESVILLE 63 35 47 32 / 100 70 5 10 MACON 73 39 55 33 / 90 100 5 5 ROME 68 33 48 31 / 100 40 5 10 PEACHTREE CITY 68 36 51 32 / 100 60 5 5 VIDALIA 80 46 59 36 / 70 90 0 5 && .FFC WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR THE FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BARTOW...BIBB...BLECKLEY... BUTTS...CARROLL...CATOOSA...CHATTAHOOCHEE...CHATTOOGA... CHEROKEE...CLARKE...CLAYTON...COBB...COWETA...CRAWFORD...CRISP... DADE...DEKALB...DODGE...DOOLY...DOUGLAS...EMANUEL...FAYETTE... FLOYD...FORSYTH...GLASCOCK...GORDON...GREENE...GWINNETT...HALL... HANCOCK...HARALSON...HARRIS...HEARD...HENRY...HOUSTON... JACKSON...JASPER...JEFFERSON...JOHNSON...JONES...LAMAR... LAURENS...MACON...MADISON...MARION...MERIWETHER...MONROE... MONTGOMERY...MORGAN...MUSCOGEE...NEWTON...NORTH FULTON... OCONEE...OGLETHORPE...PAULDING...PEACH...PIKE...POLK...PULASKI... PUTNAM...ROCKDALE...SCHLEY...SOUTH FULTON...SPALDING...STEWART... SUMTER...TALBOT...TALIAFERRO...TAYLOR...TELFAIR...TOOMBS... TREUTLEN...TROUP...TWIGGS...UPSON...WALKER...WALTON...WARREN... WASHINGTON...WEBSTER...WHEELER...WHITFIELD...WILCOX...WILKES... WILKINSON. HIGH WIND WARNING UNTIL 6 PM EST THIS EVENING FOR THE FOLLOWING ZONES: DAWSON...FANNIN...GILMER...LUMPKIN...MURRAY...PICKENS... TOWNS...UNION...WHITE. FLOOD WATCH FROM 9 AM EST THIS MORNING THROUGH THIS EVENING FOR THE FOLLOWING ZONES: BARTOW...CATOOSA...CHATTOOGA...CHEROKEE... COBB...DADE...DAWSON...FANNIN...FLOYD...FORSYTH...GILMER... GORDON...HARALSON...LUMPKIN...MURRAY...NORTH FULTON...PAULDING... PICKENS...POLK...TOWNS...UNION...WALKER...WHITE...WHITFIELD. WIND ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT EST TONIGHT FOR THE FOLLOWING ZONES: DAWSON...FANNIN...GILMER...LUMPKIN... MURRAY...PICKENS...TOWNS...UNION...WHITE. TORNADO WATCH UNTIL 1 PM EST THIS AFTERNOON FOR THE FOLLOWING ZONES: CATOOSA...DADE...MURRAY...WALKER...WHITFIELD. && $$ SHORT TERM...SNELSON LONG TERM....BELANGER AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
952 AM EST WED JAN 30 2013 .UPDATE... THE NEAR TERM SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 420 AM EST WED JAN 30 2013 STRONG SYSTEM WILL BE PASSING THROUGH THE AREA THROUGH TONIGHT. SHOWERS IN THE WAKE OF THUNDERSTORMS WILL CONTINUE THROUGH MID MORNING...WITH ADDITIONAL SHOWERS POSSIBLY DEVELOPING LATER TODAY. ARCTIC AIR WILL BEGIN RUSHING INTO THE AREA LATE THIS AFTERNOON...AND ANY REMAINING PRECIPITATION WILL CHANGE QUICKLY OVER TO SNOW THIS EVENING. ANOTHER UPPER LEVEL WAVE WILL PUSH THROUGH THE AREA TOMORROW AFTERNOON AND EVENING...PERHAPS BRINGING LIGHT SNOW SHOWERS TO THE AREA...FOLLOWED BY ANOTHER DISTURBANCE WITH THE POTENTIAL FOR SNOW FRIDAY NIGHT INTO SATURDAY. && .NEAR TERM /REST OF TODAY/... ISSUED AT 943 AM EST WED JAN 30 2013 RAIN ASSOCIATED WITH OVERNIGHT STORMS HAS MOVED OUT OF THE AREA. RADAR MOSAIC SHOWS A LINE OF SHOWERS OVER CENTRAL ILLINOIS AND SHORT TERM MODELS SHOW THIS LINE MOVING INTO THE WESTERN COUNTIES AROUND 17-18Z AND ACROSS THE AREA FROM THERE. ALSO SOME POTENTIAL FOR A FEW SHOWERS TO POP UP AHEAD OF THIS LINE AND MOVE NORTHEAST TO THE AREA FROM SOUTHERN ILLINOIS/WESTERN KENTUCKY. HAVE ADDED SOME DETAIL TO THE NEXT FEW HOURS COMPLETELY REMOVING RAIN FOR MOST OF THE AREA AND THEN BRING BACK CHANCES STARTING AT 17Z AND RAMPING UP FROM THERE. TIMING OF CHANGEOVER TO SNOW STILL LOOKS LIKE IT COULD HAPPEN IN THE NORTHWEST AFTER 21Z BUT SHOULD NOT REACH THE REST OF THE AREA UNTIL AFTER 0Z. WINDS THIS MORNING ARE LIGHTER THAN FORECAST BUT SOUNDINGS STILL HAVE THEM INCREASING QUITE A BIT THIS AFTERNOON WITH GUSTS AROUND 40 MPH EXPECTED THIS AFTERNOON. WITH THE SLIGHTLY SLOWER ARRIVAL OF THE COLD AIR BEHIND THE FINAL COLD FRONT /STILL OVER WESTERN ILLINOIS/ AND LESS RAIN AROUND THE NEXT FEW HOURS EXPECT TEMPERATURES TO RISE IN THE CENTRAL AND EASTERN COUNTIES AND REMAIN STEADY IN THE WEST UNTIL MID AFTERNOON WHEN THEY SHOULD START TO PLUMMET IN THE WEST AND THIS WILL OVERSPREAD THE AREA THROUGH THE EVENING. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... ISSUED AT 420 AM EST WED JAN 30 2013 AS THE SECOND COLD FRONT PASSES THE AREA EARLY THIS EVENING...EXPECT THAT ALL PRECIP WILL CHANGE TO SNOW BY AROUND 02-03Z. PRECIP SHOULD BE SNOW ACROSS THE WEST BY 00Z...WITH CHANGEOVER PROGRESSING RAPIDLY ACROSS THE AREA. MOST PRECIP SHOULD BE DONE BY 06Z. BRIEF LULL IN PRECIP CHANCES EXPECTED LATE TONIGHT INTO EARLY THURSDAY. ADDITIONAL WAVE WILL PUSH THROUGH THE AREA LATE THURSDAY INTO THURSDAY NIGHT...AND MODELS ARE A BIT MORE BULLISH ON THIS WAVE THAN PREVIOUSLY. ADDITIONALLY...FORCING IS IMPROVED...WITH DECENT Q VECTOR CONVERGENCE AND EVEN SOME GOOD FRONTOGENESIS AND MODERATE EPV. WILL LEAN TO HIGHER END OF THE GUIDANCE ENVELOPE. THIS MAY PRODUCE LIGHT ACCUMULATIONS OF AN INCH OR LESS ACROSS PORTIONS OF THE AREA. FINALLY...ADDITIONAL WAVE WILL APPROACH ON FRIDAY NIGHT...LOW CHANCE POPS APPEAR REASONABLE. WINDS TONIGHT POST FRONT MAY GUST TO AROUND 30-35KT AT TIMES...AS ACCORDING TO BUFKIT SOUNDINGS AND LOW LEVEL WIND PROGS OFF MODELS. AGAIN THIS IS BELOW ADVISORY CRITERIA. ON TEMPS...CONSENSUS APPEARED REASONABLE AND ONLY A FEW MINOR TWEAKS REQUIRED. DID BUMP TEMPS DOWN SLIGHTLY THROUGHOUT WITH COLD ADVECTION ONGOING UNTIL LATE IN THE PERIOD. && .LONG TERM /SATURDAY THROUGH TUESDAY/... ISSUED AT 305 AM EST WED JAN 30 2013 MODELS KEEP A BROAD UPPER TROUGH ACROSS EASTERN CANADA...GREAT LAKES AND NORTHEAST U.S. THROUGH THE PERIOD. THERE ARE A COUPLE OF WEAK UPPER DISTURBANCES THAT WILL ROTATE ACROSS OUR AREA WITH ONE OCCURRING AROUND SATURDAY...ANOTHER ONE LATE MONDAY AND THE EURO HAS ONE OCCURRING LATE TUESDAY...WHICH THE GFS DOES NOT. CONFIDENCE OF TUESDAY SYSTEM IS VERY LOW...HOWEVER ALL MODELS HAVE TRENDED WITH HIGHER POPS THEN...SO WILL ADD SLIGHT CHANCE OF SNOW SHOWERS DAY 7. OTHERWISE ALL BLEND POPS SEEM REASONABLE IN MOST OTHER CASES. AS FAR AS TEMPERATURES ARE CONCERNED MODELS HAVE TRENDED A LITTLE COLDER OVER THE WEEKEND AND TUESDAY. IN MOST CASES WENT WITH A BLEND OF ALL BLEND AND CONSALL NUMBERS. && .AVIATION /DISCUSSION FOR THE 301500Z TAF ISSUANCE/... ISSUED AT 940 AM EST TUE JAN 29 2013 WIDESPREAD RAIN HAS MOVED EAST OF THE TERMINALS THIS MORNING WITH IFR AND LOWER CONDITIONS PERSISTING ACROSS THE REGION. MADE ADJUSTMENTS TO WIND SPEED/DIRECTION BASED ON CURRENT OBS. ALSO AM LESS OPTIMISTIC IN CEILING IMPROVEMENT THROUGH EARLY AFTERNOON WITH CEILINGS BELOW 1000FT EXTENDING BACK INTO EASTERN ILLINOIS. MOST RECENT HRRR GUIDANCE AND OBS AGREE ON SCATTERED SHOWERS EXPANDING BACK INTO THE REGION BY EARLY AFTERNOON AS THE COLD FRONT APPROACHES. WIND GUSTS WILL INCREASE THROUGH THE AFTERNOON ALONG AND BEHIND THE FRONTAL PASSAGE. 12Z DISCUSSION FOLLOWS. MOSTLY MVFR CEILINGS THROUGH THE PERIOD WITH GUSTY WINDS THIS AFTERNOON AND TONIGHT. LOW PRESSURE OVER NORTHEAST ILLINOIS WILL TRACK NORTHEAST ACROSS THE GREAT LAKES AS A COLD FRONT MOVES ACROSS CENTRAL INDIANA LATER TODAY. AREA OF RAIN CURRENTLY ACROSS CENTRAL INDIANA WILL MOVE ON TO THE EAST. HOWEVER RAPID REFRESH AND OTHER MODELS INDICATE SCATTERED SHOWERS MOVING BACK IN ACROSS TAF SITES BY MIDDAY AND WITH PRECIPITATION CHANGING TO LIGHT SNOW SHOWERS OR FLURRIES BY EVENING. WITH THE EXCEPTION OF KLAF CEILINGS CURRENTLY AT OR ABOVE 3 THOUSAND. BUT UPSTREAM THEY ARE MUCH LOWER AND THESE LOWER CEILINGS WILL SPREAD ACROSS TAF SITES LATER TODAY. AT TIME BELIEVE CEILINGS SHOULD AVERAGE ABOUT 15 HUNDRED FEET BY THIS AFTERNOON AND EARLY TONIGHT WITH SOME IMPROVEMENT LATE TONIGHT. WINDS HAVE TEMPORARILY BECOME LIGHT THIS MORNING BUT WILL PICK UP AGAIN BY THIS AFTERNOON AFTER COLD FRONT MOVES THROUGH AND WITH SOME AREAS GUSTING UP TO 30 KNOTS LATE TODAY AND TONIGHT.. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...NIELD NEAR TERM...CP SHORT TERM...NIELD LONG TERM....JH AVIATION...JH/RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
942 AM EST WED JAN 30 2013 .UPDATE... AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 420 AM EST WED JAN 30 2013 STRONG SYSTEM WILL BE PASSING THROUGH THE AREA THROUGH TONIGHT. SHOWERS IN THE WAKE OF THUNDERSTORMS WILL CONTINUE THROUGH MID MORNING...WITH ADDITIONAL SHOWERS POSSIBLY DEVELOPING LATER TODAY. ARCTIC AIR WILL BEGIN RUSHING INTO THE AREA LATE THIS AFTERNOON...AND ANY REMAINING PRECIPITATION WILL CHANGE QUICKLY OVER TO SNOW THIS EVENING. ANOTHER UPPER LEVEL WAVE WILL PUSH THROUGH THE AREA TOMORROW AFTERNOON AND EVENING...PERHAPS BRINGING LIGHT SNOW SHOWERS TO THE AREA...FOLLOWED BY ANOTHER DISTURBANCE WITH THE POTENTIAL FOR SNOW FRIDAY NIGHT INTO SATURDAY. && .NEAR TERM /TODAY/... ISSUED AT 420 AM EST WED JAN 30 2013 STORMS ARE EXITING THE FORECAST AREA AT THIS TIME...WITH ONLY STRATIFORM RAIN IN THE WAKE OF THE STORMS ACROSS THE AREA. EXPECT A LULL PERHAPS LATER THIS MORNING WITH THE POTENTIAL FOR ADDITIONAL SHOWERS LATER THIS AFTERNOON AS THE UPPER WAVE APPROACHES. SECONDARY COLD FRONT WILL PASS STARTING LATE THIS AFTERNOON/EARLY EVENING. BUFKIT SOUNDINGS HAVE BACKED OFF ON WIND GUSTS QUITE A BIT...AND NOW NOT EXPECTING ADVISORY CRITERIA GUSTS...MORE LIKE 30 MPH. GUSTS MAY BE STRONGER TONIGHT POST FRONTAL. FAST MOVING NATURE OF STORMS CONTRIBUTED TO MUCH LESS RAINFALL THAN ORIGINALLY FEARED...WITH AMOUNTS THROUGH 12Z LIKELY TO BE AROUND AN INCH WITH ISOLATED HIGHER AMOUNTS. THUS...WILL CANCEL THE FLOOD WATCH. RIVERS MAY STILL GO INTO FLOOD...BUT WIDESPREAD AREAL FLOOD THREAT HAS DIMINISHED SIGNIFICANTLY. ON TEMPS...RELIED HEAVILY ON NAM WETBULB TEMP PROGS...AS PRECIP WILL BE ONGOING AT TIMES THROUGHOUT THE DAY AND INITIAL PROGS COMPARED FAVORABLY TO OBS. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... ISSUED AT 420 AM EST WED JAN 30 2013 AS THE SECOND COLD FRONT PASSES THE AREA EARLY THIS EVENING...EXPECT THAT ALL PRECIP WILL CHANGE TO SNOW BY AROUND 02-03Z. PRECIP SHOULD BE SNOW ACROSS THE WEST BY 00Z...WITH CHANGEOVER PROGRESSING RAPIDLY ACROSS THE AREA. MOST PRECIP SHOULD BE DONE BY 06Z. BRIEF LULL IN PRECIP CHANCES EXPECTED LATE TONIGHT INTO EARLY THURSDAY. ADDITIONAL WAVE WILL PUSH THROUGH THE AREA LATE THURSDAY INTO THURSDAY NIGHT...AND MODELS ARE A BIT MORE BULLISH ON THIS WAVE THAN PREVIOUSLY. ADDITIONALLY...FORCING IS IMPROVED...WITH DECENT Q VECTOR CONVERGENCE AND EVEN SOME GOOD FRONTOGENESIS AND MODERATE EPV. WILL LEAN TO HIGHER END OF THE GUIDANCE ENVELOPE. THIS MAY PRODUCE LIGHT ACCUMULATIONS OF AN INCH OR LESS ACROSS PORTIONS OF THE AREA. FINALLY...ADDITIONAL WAVE WILL APPROACH ON FRIDAY NIGHT...LOW CHANCE POPS APPEAR REASONABLE. WINDS TONIGHT POST FRONT MAY GUST TO AROUND 30-35KT AT TIMES...AS ACCORDING TO BUFKIT SOUNDINGS AND LOW LEVEL WIND PROGS OFF MODELS. AGAIN THIS IS BELOW ADVISORY CRITERIA. ON TEMPS...CONSENSUS APPEARED REASONABLE AND ONLY A FEW MINOR TWEAKS REQUIRED. DID BUMP TEMPS DOWN SLIGHTLY THROUGHOUT WITH COLD ADVECTION ONGOING UNTIL LATE IN THE PERIOD. && .LONG TERM /SATURDAY THROUGH TUESDAY/... ISSUED AT 305 AM EST WED JAN 30 2013 MODELS KEEP A BROAD UPPER TROUGH ACROSS EASTERN CANADA...GREAT LAKES AND NORTHEAST U.S. THROUGH THE PERIOD. THERE ARE A COUPLE OF WEAK UPPER DISTURBANCES THAT WILL ROTATE ACROSS OUR AREA WITH ONE OCCURRING AROUND SATURDAY...ANOTHER ONE LATE MONDAY AND THE EURO HAS ONE OCCURRING LATE TUESDAY...WHICH THE GFS DOES NOT. CONFIDENCE OF TUESDAY SYSTEM IS VERY LOW...HOWEVER ALL MODELS HAVE TRENDED WITH HIGHER POPS THEN...SO WILL ADD SLIGHT CHANCE OF SNOW SHOWERS DAY 7. OTHERWISE ALL BLEND POPS SEEM REASONABLE IN MOST OTHER CASES. AS FAR AS TEMPERATURES ARE CONCERNED MODELS HAVE TRENDED A LITTLE COLDER OVER THE WEEKEND AND TUESDAY. IN MOST CASES WENT WITH A BLEND OF ALL BLEND AND CONSALL NUMBERS. && .AVIATION /DISCUSSION FOR THE 301500Z TAF ISSUANCE/... ISSUED AT 940 AM EST TUE JAN 29 2013 WIDESPREAD RAIN HAS MOVED EAST OF THE TERMINALS THIS MORNING WITH IFR AND LOWER CONDITIONS PERSISTING ACROSS THE REGION. MADE ADJUSTMENTS TO WIND SPEED/DIRECTION BASED ON CURRENT OBS. ALSO AM LESS OPTIMISTIC IN CEILING IMPROVEMENT THROUGH EARLY AFTERNOON WITH CEILINGS BELOW 1000FT EXTENDING BACK INTO EASTERN ILLINOIS. MOST RECENT HRRR GUIDANCE AND OBS AGREE ON SCATTERED SHOWERS EXPANDING BACK INTO THE REGION BY EARLY AFTERNOON AS THE COLD FRONT APPROACHES. WIND GUSTS WILL INCREASE THROUGH THE AFTERNOON ALONG AND BEHIND THE FRONTAL PASSAGE. 12Z DISCUSSION FOLLOWS. MOSTLY MVFR CEILINGS THROUGH THE PERIOD WITH GUSTY WINDS THIS AFTERNOON AND TONIGHT. LOW PRESSURE OVER NORTHEAST ILLINOIS WILL TRACK NORTHEAST ACROSS THE GREAT LAKES AS A COLD FRONT MOVES ACROSS CENTRAL INDIANA LATER TODAY. AREA OF RAIN CURRENTLY ACROSS CENTRAL INDIANA WILL MOVE ON TO THE EAST. HOWEVER RAPID REFRESH AND OTHER MODELS INDICATE SCATTERED SHOWERS MOVING BACK IN ACROSS TAF SITES BY MIDDAY AND WITH PRECIPITATION CHANGING TO LIGHT SNOW SHOWERS OR FLURRIES BY EVENING. WITH THE EXCEPTION OF KLAF CEILINGS CURRENTLY AT OR ABOVE 3 THOUSAND. BUT UPSTREAM THEY ARE MUCH LOWER AND THESE LOWER CEILINGS WILL SPREAD ACROSS TAF SITES LATER TODAY. AT TIME BELIEVE CEILINGS SHOULD AVERAGE ABOUT 15 HUNDRED FEET BY THIS AFTERNOON AND EARLY TONIGHT WITH SOME IMPROVEMENT LATE TONIGHT. WINDS HAVE TEMPORARILY BECOME LIGHT THIS MORNING BUT WILL PICK UP AGAIN BY THIS AFTERNOON AFTER COLD FRONT MOVES THROUGH AND WITH SOME AREAS GUSTING UP TO 30 KNOTS LATE TODAY AND TONIGHT.. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...NIELD NEAR TERM...NIELD SHORT TERM...NIELD LONG TERM....JH AVIATION...JH/RYAN
AREA FORECAST DISCUSSION
NWS TOPEKA KS
418 AM CST WED JAN 30 2013 .DISCUSSION... MAIN CONCERNS FOR THE FORECAST IS SNOWFALL THIS MORNING AND ARCTIC AIR RETURNING TO THE CWA ON THURSDAY AND FRIDAY. TODAY THROUGH FRIDAY MORNING...SNOW HAS BEEN FALLING FOR MUCH OF THE NIGHT WITH A HEAVY BAND THAT HAS BEEN SLOWLY TRAVERSING THE CWA THROUGHOUT THE OVERNIGHT HOURS. HEAVIEST BAND DEVELOPED IN THE DEFORMATION ZONE...NEAR THE AREA OF BEST MID LEVEL FRONTOGENESIS COUPLED WITH AN AREA OF STRONG OMEGA AND NEGATIVE EPV. HOWEVER...THE BAND WAS SLOWLY ERODING AS MODELS DEPICT THE DISSIPATION OF THE FRONTGENESIS AS THE BETTER FORCING MOVES NORTHEAST. THEREFORE...SHOULD SEE THE HEAVIEST BAND CONTINUE TO ERODE THROUGHOUT THE MORNING AS IT PUSHES SOUTHEAST. LIGHT SNOW WILL EVENTUALLY TAPER OFF DURING THE MORNING HOURS WITH THE FAR EASTERN COUNTIES SEEING AN END AROUND THE NOON HOUR AS THE BETTER FORCING AGAIN LIFTS TO THE NORTHEAST. BECAUSE OF THE SLOWER MOVEMENT OF THE PRECIPITATION...OPTED TO EXTEND THE WINTER WEATHER ADVISORIES TILL 9 AM FOR THE WESTERN COUNTIES AND NOON FOR THE EASTERN COUNTIES. TOTAL SNOW ACCUMULATIONS WILL BE GREATEST NORTH OF INTERSTATE 70 WITH 2 TO 4 INCHES AND LOCALLY HIGHER AMOUNTS TO NEAR 6 INCHES. SOUTH OF INTERSTATE 70...TOTAL ACCUMULATIONS OF 1 TO 3 INCHES WITH LOCALLY HIGHER AMOUNTS POSSIBLE. WINDS PICKING UP TO 35 MPH WILL ALSO CAUSE CAUSE BLOWING AND DRIFTING AS WELL AS REDUCED VISIBILITIES ESPECIALLY THIS MORNING. AFTERNOON HIGHS TODAY WILL REACH INTO THE 20`S TO LOW 30`S. LONGWAVE TROUGH MOVES OUT OF THE CWA THIS AFTERNOON AS 85KT 500MB JET CORE ASSOCIATED WITH THE NEXT SHRTWV PUSHES IT TO THE EAST AND GIVES THE LONGWAVE TROUGH A BIT OF A NEGATIVE TILT OVER THE OHIO VALLEY. SURFACE LOW DEVELOPS OVER THE WESTERN HIGH PLAINS TONIGHT IN RESPONSE TO THE SHRTWV...WHICH WILL CAUSE WINDS TO BRIEFLY SWITCH TO THE WEST/SOUTHWEST THIS EVENING AND TONIGHT. HIGH TEMPERATURES FOR THE DAY THURSDAY WILL BE REALIZED DURING THE MORNING HOURS WITH HIGHS IN THE 20`S AS AN ARCTIC COLD FRONT IS PUSHED RAPIDLY SOUTHEAST ACROSS THE PLAINS AND INTO THE CWA BY THURSDAY MORNING. SIGNIFICANT CAA WILL LAG BEHIND THE FRONT UNTIL THE AFTERNOON WHERE TEMPERATURES SHOULD BEGIN DROPPING AFTER THE NOON HOUR. TEMPERATURES BY SUNSET WILL ONLY BE IN THE TEENS AND LOW 20`S BY SUNSET. OVERNIGHT LOWS WILL BE BITTERLY COLD WITH LOWS IN THE SINGLE DIGITS FOR MUCH OF THE CWA. WITH GUSTY WINDS TO AROUND 25 MPH THURSDAY AFTERNOON...COULD SEE WIND CHILLS BELOW ZERO OVER THE FAR NORTHERN COUNTIES AND SINGLE DIGITS FOR THE REST OF THE AREA. BYRNE LONG TERM (FRIDAY AND TUESDAY)... FRIDAY...THE DEEPER LONGER WAVE-LENGTH UPPER LEVEL TROUGH ACROSS THE GREAT LAKES AND OH RIVER VALLEY WILL SHIFT EAST INTO NEW ENGLAND AND THE MID ATLANTIC STATES. THE SFC RIDGE OF HIGH PRESSURE WILL ALSO SHIFT EAST ACROSS THE MID AND LOWER MS RIVER VALLEY. HIGHS ON FRIDAY WILL WARM SLIGHTLY...THOUGH DEEPER SNOW COVER ACROSS THE NORTHERN HALF OF THE CWA MAY KEEP HIGHS IN THE LOWER TO MID 30S...WITH MID TO UPPER 30S ACROSS THE SOUTHERN COUNTIES. FRIDAY NIGHT THROUGH WEDNESDAY...THE UPPER LEVEL FLOW WILL BE WEST-NORTHWEST ACROSS THE PLAINS. EXPECT DRY CONDITIONS. I KEPT HIGHS COOLER ON SATURDAY ACROSS THE NORTHERN COUNTIES OF THE CWA DUE TO THE SNOW COVER. SATURDAY HIGHS WILL RANGE FROM THE UPPER 30S ALONG THE NE BORDER TO THE MID AND UPPER 40S SOUTH OF I-70. HIGHS WILL SLOWLY WARM INTO THE LOWER TO MID 50S SUNDAY THROUGH TUESDAY. GARGAN && .AVIATION... DEFORMATION BAND OF SNOW HAS FORMED TO THE WEST OF THE TERMINALS...AND THE RAP AND NAM CONTINUE TO SHOW THIS BAND MOVING ACROSS NORTHEAST KANSAS OVERNIGHT. TIMING IS SEVERAL HOURS SLOWER FROM THE PREV FORECAST WITH SNOW LIKELY PERSISTING AT TOP AND FOE UNTIL 14Z. MODELS ALSO SUGGEST A LACK OF ICE IN THE TOP OF THE CLOUD INITIALLY. WITH SEVERAL REPORTS OF PL UPSTREAM...HAVE INTRODUCED A MIX OF -SNPL UNTIL THE BETTER DEFORMATION BAND MOVES IN AND SATURATES THE DENDRITIC GROWTH ZONE FOR A PERIOD OF MODERATE SNOW. CONFIDENCE IS HIGH THAT THERE WILL BE IFR AND LIFR CONDITIONS DURING THE NEXT 8 TO 12 HOURS. WOLTERS && .TOP WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 9 AM CST THIS MORNING FOR KSZ008>010-020>023-034>038. WINTER WEATHER ADVISORY UNTIL NOON CST THURSDAY FOR KSZ011-012- 024-026-039-040. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
649 AM EST WED JAN 30 2013 .SYNOPSIS... WELL ABOVE NORMAL TEMPERATURES...GUSTY WINDS AND RAIN SHOWERS TODAY AHEAD OF A STRONG COLD FRONT WHICH WILL PASS THROUGH LATE THIS AFTERNOON AND EVENING. MUCH COLDER AIR AND SNOW SHOWERS FOR THE REMAINDER OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WILL ISSUE A WIND ADVISORY TODAY FOR THE HIGHEST RIDGES IN GARRETT...PRESTON AND TUCKER COUNTIES. LATEST RUC FORECAST SOUNDINGS ON BUFKIT ARE SHOWING 60-65KTS TODAY JUST ABOVE 2500FT IN THESE COUNTIES. PER HPC DESIGNATION OF MOD RISK FOR EXCESSIVE RAINFALL AND COUNTIES WITH THE LOWEST FFG...WILL ISSUE FLOOD WATCH FOR PORTIONS OF THE SOUTH AND EAST TODAY AND TONIGHT. STRONG COLD FRONT WILL MOVE INTO W OHIO AFTER DAWN. SHOWERS AND SOME STORMS WILL ACCOMPANY THE FRONT AS IT CONTINUES ITS SLOW EASTWARD PROGRESSION. EXPECT A GOOD SOAKING TODAY WITH ONE- HALF TO ONE INCH OF RAIN FOR MUCH OF THE REGION. IN THE FLOOD WATCH COUNTIES...1 TO 2 INCHES OF RAIN IS POSSIBLE WITH THE BULK OF IT COMING THIS AFTERNOON AND EVENING. THE WATCH MAY NEED TO BE EXPANDED PARTICULARLY IF A LINE OF STRONG SLOW MOVING CONVECTION DEVELOPS. THE OTHER PROBLEM WILL BE THE POTENTIAL FOR STRONG WIND GUSTS ACROSS THE REST OF MY COUNTIES. LATEST CONVECTIVE OUTLOOK FOR TODAY PUT MUCH OF THE AREA IN A SLIGHT RISK. THINK THE BEST WAY TO HANDLE THIS IS TO INCLUDE THE POSSIBILITY OF SEVERE STORMS TODAY WITH DAMAGING WINDS. TEMPS WILL REMAIN WELL ABOVE NORMAL TODAY. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... MUCH COLDER AIR WILL RAPIDLY MOVE IN TONIGHT. LEFT OVER RAIN SHOWERS WILL CHANGE OVER TO SNOW SHOWERS AS THE NIGHT PROGRESSES. THINK THE BEST LOCATION FOR ANY ACCUMULATIONS WILL BE ACROSS THE HIGHER ELEVATIONS. IT DOES NOT APPEAR THAT THE SFC TEMPS WILL RESPOND QUICK ENOUGH ELSEWHERE TO ALLOW FOR ACCUMULATION. CONCERNED ABOUT DAMAGING WINDS BEHIND THE FRONT AS WELL. VERY STRONG CAA...COMBINED WITH PRES RISES OF 6 TO 8 MBS IS PRESENTING A PERIOD OVERNIGHT THAT MAY REQUIRE A WIND ADVISORY. WILL ALLOW THE NEXT SHIFT TO TAKE A CLOSER LOOK AT THIS. RISK FOR SNOW SHOWERS...MAINLY OVER THE FAR NORTH AND RIDGES...WILL CONTINUE THROUGH THE THURSDAY. TEMPERATURES WILL BE STEADY OR SLOWLY FALLING WITH GUSTY WINDS CONTINUING. AT THIS POINT...HAVE VERY LOW CONFIDENCE ON EFFECTS FROM SHORTWAVE WHICH WILL DIVE SOUTHWARD ACROSS THE REGION THU NIGHT. LATEST MODEL RUNS ARE HINTING AT SOME ACCUMULATING SNOWS...PARTICULARLY OVER THE SOUTHERN HALF. THU NIGHT/FRI MORN FORECAST WILL NEED FINE TUNING AS MODELS GET BETTER HANDLE ON LOCATION OF WAVE. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... UNCERTAINTY LIES IN THE FORECAST AS MODELS SEEM TO BE IN DISAGREEMENT. GFS/ECMWF DO SHOW A SHORTWAVE TROUGH MOVING OVER THE AREA ON THE WEEKEND AND THUS BRINGING A CLIPPER SOUTHEAST WITH THE GFS BRINGING HIGHER AMOUNTS OF SNOW THAN THE ECMWF. POSSIBLE LAKE ENHANCED AND/OR TERRAIN ENHANCED SNOW COULD DEVELOP AFTER THE PASSAGE OF THE QUICK MOVING SYSTEM. THE GFS BRINGS IN ANOTHER STRONGER CLIPPER OVER THE GREAT LAKES AND NORTHERN OHIO VALLEY MONDAY NIGHT INTO TUESDAY WHILE THE ECMWF TRACKS THE SYSTEM MORE NORTHEAST AND BRINGS PRECIPITATION TO OUR AREA ALONG A COLD FRONT. HIGH PRESSURE BUILDS BEHIND THE SYSTEM LEAVING THE MID WEEK DRY. HPC TRENDED TOWARDS THE ECMWF RUN THE LATTER PART OF THE EXTENDED AND THUS FORECAST IS BASED ON GFS/HPC GUIDANCE KEEPING SLIGHT TO CHANCE POPS. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... VFR WL DCRS TO MVFR IN SHRA LT MRNG INTO THIS AFTN AS A STG CDFNT APRCHS FM THE W. SHRA EXTEND WELL OUT AHEAD OF THE FNT. SHOULD SEE ADDNL DVLPMNT ALG THE FNT THIS AFTN. STLT/MESO/RAOB INSTAB CHARTS SHOW SOME INSTAB ALG/AHD OF THE FNT. COULD SEE A TS AT ANY OF THE SITES ESP S OF I-80 THIS AFTN BUT DUE TO PLENTY OF UNCERTAINTY IN INSTAB/TIMING HAVE KEPT THEM OUT OF THE TAFS ATTM. INCLUDED A TEMPO FOR +SHRA AND STG WND GUSTS AT ZZV LT MRNG. THIS MAY HAVE TO BE ADDED TO OTHER SITES AS WELL IN LTR FCSTS. STG LLVL JET WL KEEP THE THREAT OF LLWS ACRS THE RGN THRU THIS MRNG. FROPA/WSHFT TO THE W EXPD THIS EVE WITH MVFR CONDS CONTG. EVEN A FEW SHSN PSBL OVRNGT. .OUTLOOK.../THURSDAY THROUGH SUNDAY/... PERIODIC RESTRICTION ARE EXPD THRU THE PD AS SVRL DISTURBANCES MOVE THRU IN COLD W-NW FLOW. GUSTY W WNDS ARE ALSO EXPTD THU. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...FLOOD WATCH FROM 1 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR MDZ001. WIND ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MDZ001. OH...NONE. PA...FLOOD WATCH FROM 1 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR PAZ016-023-031-073>076. WV...FLOOD WATCH FROM 1 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR WVZ012-021>023-041. WIND ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR WVZ023-041. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS BALTIMORE MD/WASHINGTON DC
629 AM EST WED JAN 30 2013 .SYNOPSIS... LOW PRESSURE IS CENTERED THIS MORNING OVER MICHIGAN. FROM THIS A WARM EXTENDS ALONG THE MASON-DIXON LINE WHILE A COLD FRONT EXTENDS FROM INDIANA TO ARKANSAS. THE COLD FRONT WILL MOVE THROUGH THE MID ATLANTIC STATES THIS EVENING. ANOTHER COLD FRONT WILL MOVE THROUGH THE REGION FRIDAY...FOLLOWED BY HIGH PRESSURE SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 11Z...WARM FRONT IS JUST SOUTH OF THE MASON-DIXON LINE. A COLD FRONT IS THROUGH CHICAGO WITH A PREFRONTAL BAND OF HEAVY SHOWERS ASSOCIATED WITH A STRONG GULF PLUME THAT EXTENDS FROM BATON ROUGE TO CINCINNATI. A WIDE SWATH OF TRAILING STRATIFORM IS OVER WRN IL AND IN. THIS COLD FRONT AND PREFRONTAL ACTIVITY WILL PROGRESS EAST TOWARD THE MID-ATLANTIC THROUGH TODAY. THE 08Z HRRR HAS SLOWED THE CURRENT PREFRONTAL BAND...REACHING THE ALLEGHENY FRONT AROUND 20Z WHICH SEEMS TO BE A REASONABLE TIMEFRAME. FLASH FLOOD WATCH IS IN EFFECT FOR COUNTIES ALONG THE ALLEGHENY FRONT AS WELL AS HAMPSHIRE/HARDY WHERE 6 HR FLASH FLOOD GUIDANCE IS AROUND AN INCH /1-2 INCHES ARE EXPECTED FOR THOSE COUNTIES/. ANY OTHER FLOODING LOOKS TO BE IN URBAN AREAS LIKE BALT-WASH. OTHERWISE A WELCOME HEAVY RAINFALL THOUGH DAMAGING WINDS ARE A REAL THREAT. SEVERE THREAT. VERY STRONG SHEAR/SLY LLJ AND VERY LOW CAPE WILL RESULT IN A DYNAMIC BAND/QLCS LINE SPREADING EAST ACROSS THE CWA LATER THIS AFTERNOON THROUGH THE EVENING HOURS. GUSTS IN EXCESS OF 50 KT POSSIBLE WITH THIS BAND ACROSS THE LWX CWA. KEPT THUNDER CHANCES AT JUST CHANCE THOUGH THE MIDWEST HAS HAD A FAIR SHARE OF THUNDER TONIGHT. THIS COLD FRONT MAY FORM AN AXIS FOR BOTH HEAVY RAIN AND TORNADOES. STRONG LOW LEVEL WIND SHEAR WILL ALLOW FOR HORIZONTAL VORTICITY ROLLS. THE WARM FRONT AND A FEW MILES INTO THE COLD SIDE ARE TEXTBOOK PRIME AREAS FOR TORNADOES. PROGRESSION OF THIS WARM FRONT TODAY WILL BE KEY. WIND. A STRONG LLJ AHEAD OF THIS FRONT WILL INCREASE OVERHEAD THROUGH THE DAY. A WIND ADVISORY IS IN EFFECT FOR MAJOR RIDGELINES BLUE RIDGE AND WEST FROM NOON THROUGH TONIGHT. WIND SHIFT TO WEST WITH FRONT WILL OCCUR SHORTLY AFTER MIDNIGHT. AS OF NOW WLY FLOW LOOKS TO BE BELOW 40 KT GUSTS...SO LATER SHIFTS WILL HAVE TO HONE IN ON IF THERE IS A WIND THREAT FOR LATE TONIGHT/THURSDAY MORNING. TEMPERATURES. WARM AHEAD OF THE COLD FRONT WITH UPR 50S OUT THERE NOW EASILY REACHING THE UPR 60S/LOW 70S BEFORE PREFRONTAL PRECIP/CLOUDS LIMIT INCREASES. 850MB TEMPS ARE NEAR 12C...SO MID 70S WOULD BE POSSIBLE IN SUNNY CONDITIONS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/... WARM EVENING AHEAD OF THE PREFRONTAL RAIN BANDS. PRECIP SLOWLY CUTS OF WITH STRATIFORM TRAILING MAIN BAND FOR A FEW HOURS. UPSLOPE SNOW OF ONLY A COUPLE INCHES. NO WINTER WEATHER ADVISORY EXPECTED. WITH COLD AIR ADVECTION...MIN TEMPS TONIGHT WILL BE SIMILAR TO THE HIGH TEMPS FOR THURSDAY. && .LONG TERM /THURSDAY THROUGH TUESDAY/... AFTR TUE AND TDA`S VERY WARM TEMPS THE RGN WL RETURN TO MORE NORMAL LATE JAN/ERLY FEB TEMPS FOR THE XTND PD. BRZY/WINDY WL BE THE OPERATIVE WORDS FOR THU AS HIGH PRES BUILDS INTO THE RGN. TEMPS THU WL BE 25 DEGS COOLER THAN TDA. UPSLOPE SNSH WL ALSO BE A CONCERN W/ SVRL INCHES OF ACCUM PSBL IN THE HIGHLANDS. AM ADVSRY MAY BE REQUIRED. HIGH PRES WL BUILD INTO THE RGN FRI AFTN AND SAT. HIGHS GNRLY IN THE U30S E OF THE MTNS. LOWS IN THE 20S. UPPER-LEVEL DISTURBANCES WILL BRING A CHANCE FOR SNOW SHOWERS...W/ THE BEST CHCS BEING ACROSS THE NORTHERN AND WESTERN CWA. DURG THE XTND PD FAST UPR LVL WL PREVAIL..AND W/ THIS IS THE PTNL FOR MORE ALBERTA CLIPPERS. A DISTURBANCE WILL PASS THROUGH SATURDAY NIGHT. ANOTHER MAY IMPACT THE AREA TUE. HIGHS CONT IN THE U30S/L40S SUN THRU TUE. LOWS IN THE MU20S. && .AVIATION /11Z WEDNESDAY THROUGH SUNDAY/... MVFR CIGS SPREADING NORTH FROM SRN VA HAVE CROSSED IAD AND WILL MOVE ACROSS THE DC METRO THROUGH THE MID MORNING HOURS. SLY LOW LEVEL WIND SHEAR INCREASES TODAY PEAKING TONIGHT JUST AHEAD OF A COLD FRONT. CHANCES FOR THUNDER WITH VERY GUSTY WINDS AND HEAVY RAINFALL...ON THE ORDER OF 50 KT. WINDS SHIFT WEST AND DECREASE LATE TONIGHT. GUSTY NW WINDS XPCTD THU. SKIES/CIGS SHOULD BE VFR. VFR CONDITIONS ARE EXPECTED MOST OF THE TIME THU NIGHT THROUGH SUNDAY. && .MARINE... SLY GALE EXPECTED BY LATE AFTERNOON CONTINUING UNTIL THE COLD FRONT CROSSES LATE TONIGHT. HIGH PRES BLDG INTO THE WATERS WL LKLY CONT TO CAUSE STRONG WIND GUSTS DURG THU. HV ISSUED A GALE WRNG FOR CHES BAY/LWR TIDAL PTMC...AND A STRONG SCA FOR THE RMDR OF THE WATERS. A COLD FRONT WILL PASS THROUGH THURSDAY NIGHT, GUSTY WINDS ARE EXPECTED BEHIND THE FRONT FRIDAY. HIGH PRES OVR THE WATERS SAT. ANOTHER COLD FRONT MAY IMPACT THE WATERS SUNDAY. && .TIDES/COASTAL FLOODING... COASTAL FLOOD ADVISORY IN EFFECT THIS EVENING AND TONIGHT FOR ANNE ARUNDEL AND NORTH...AND DC/ALEXANDRIA. A SOUTHERLY FLOW WILL INCREASE TODAY WITH GUSTS AROUND 35 KNOTS DURING THE AFTERNOON AND EVENING HOURS. THE STRONG SOUTHERLY FLOW WILL PUSH WATER UP THE CHESAPEAKE BAY AND THE TIDAL POTOMAC RIVER UNTIL THE COLD FRONT PASSES LATE TONIGHT. SINCE THE FLOW WILL BE SLY ONLY THE WATER IN THE BAY IS EXPECTED TO SURGE NORTHWARD. HAD THIS BEEN A SOUTHEASTERLY GALE...THEN ADDED WATER WOULD LIKELY CAUSE MODERATE FLOODING. WIND SHOULD BE STRONG ENOUGH TO CAUSE WIDESPREAD MINOR INUNDATION BEFORE HIGH TIDE...THEN CONTINUE UNTIL THE COLD FRONT...NOT NECESSARILY ONLY NEAR HIGH TIDE. LATER SHIFTS WILL HAVE TO MONITOR WATER RISE FROM LOWER PARTS OF THE BAY. NW WINDS WILL ALLOW FOR TIDAL ANOMALIES TO DECREASE THU. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...COASTAL FLOOD ADVISORY FROM 7 PM THIS EVENING TO 3 AM EST THURSDAY FOR DCZ001. MD...WIND ADVISORY FROM NOON TODAY TO 6 AM EST THURSDAY FOR MDZ501. FLASH FLOOD WATCH FROM 3 PM EST THIS AFTERNOON THROUGH LATE TONIGHT FOR MDZ501-502. COASTAL FLOOD ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM EST THURSDAY FOR MDZ007-011-014. VA...WIND ADVISORY FROM NOON TODAY TO 6 AM EST THURSDAY FOR VAZ025>030-036>040-503-504. FLASH FLOOD WATCH FROM 3 PM EST THIS AFTERNOON THROUGH LATE TONIGHT FOR VAZ503-504. COASTAL FLOOD ADVISORY FROM 7 PM THIS EVENING TO 3 AM EST THURSDAY FOR VAZ054. WV...WIND ADVISORY FROM NOON TODAY TO 6 AM EST THURSDAY FOR WVZ050- 055-501>503-505-506. FLASH FLOOD WATCH FROM 3 PM EST THIS AFTERNOON THROUGH LATE TONIGHT FOR WVZ050-055-501>506. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR ANZ530>543. SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST THURSDAY FOR ANZ530>532-535-536-538>540. GALE WARNING FROM 4 PM THIS AFTERNOON TO 6 AM EST THURSDAY FOR ANZ530>532-535-536-538>540. GALE WARNING FROM 4 PM THIS AFTERNOON TO 6 PM EST THURSDAY FOR ANZ533-534-537-541>543. && $$ UPDATE...JACKSON PREVIOUS DISCUSSION...JACKSON/WOODY!
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1028 AM EST WED JAN 30 2013 .SYNOPSIS... UNSEASONABLY WARM AIR WILL OVERSPREAD THE REGION TODAY IN ADVANCE OF A STRONG COLD FRONT. SHOWERS AND SCATTERED THUNDERSTORMS WILL DEVELOP THIS AFTERNOON IN THIS MOIST AIR MASS...AND THE RAIN WILL BE HEAVY AT TIMES. COLDER AIR BEHIND THE FRONT WILL TRIGGER LAKE EFFECT SNOWS ACROSS CENTRAL NEW YORK ON THURSDAY AND THURSDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... 9 AM UPDATE... YET ANOTHER UPDATE TO BUMP TEMPS DOWN AT KAVP WITH SENSOR READING AROUND 4 DEGREES TOO WARM. NO OTHER CHGS NEEDED AT THIS TIME AS A MAJOR WX EVENT IS IMPENDING FOR TONIGHT. 730 AM UPDATE... QUICK UPDATE TO BUMP CURRENT TEMPS UP IN WYOMING/LACKAWANNA VLYS AS KAVP IS NOW UP TO 62F. MESONET SITES IN THAT AREA ARE CURRENTLY IN THE MID-50S THUS NOT OUT OF THE QUESTION THAT SCRANTON WILKES- BARRE AIRPORT IS IN THE LOW 60S AS IT SITS AROUND 1000 FEET UP AND WITH STRONG INVERSION IN PLACE PER KALY/KOKX 12Z RAOBS. 630 AM UPDATE...MINOR T/TD TWEEKS IN THE NEAR TERM...RAISING MAXES BY A FEW DEG MAINLY FINGER LAKES AND CNTRL SRN TIER. ALSO ADDED PC SKIES FOR PARTS OF THE RGN THIS MRNG. CRUDE XTRAPOLATION OF LEADING PCPN SHIELD INDICATES ARRIVAL TIME ARND 1730Z INTO WRN STEUBEN. WE`LL SEE IF THIS HOLDS. NO OTHER CHGS. PREV BLO... 510 AM UPDATE...BUMPED UP START TIME OF THE FLOOD WATCH TO 21Z. PREV BLO.. LOTS TO LOOK AT THIS FCST PCKG. MAIN FOCUS IS ON THE APRCHNG CDFNT AND DIGGING UPR TROF...WHICH WILL BRING A ROUND OF +RA AND WIND TO THE RGN STARTING THIS AFTERNOON INTO THE OVRNGT HRS. THERE IS TREMENDOUS BUST POTNL WITH THIS FCST...STARTING OFF WITH MAX TEMPS TDA. WE ARE FCSTNG MAXES INTO THE LOWER 60S MAINLY W OF I-81...BUT IF WE GET SOME BREAKS OF SUN LATER THIS MRNG THIS FCST WILL BE ON THE COOL SIDE. WE ALSO NOTE THAT TEMPS ARE CRNTLY (AS OF 330 AM) A60 OVER MOST OF OH. ATTM WE PLAYED IT CLOSE TO THE VEST...WITH EXPECTATION THAT ANY SUNSHINE WILL BE LIMITED. BUT IT IS SOMETHING TO WATCH. MDLS HAVE BEEN LEANING SLOWER WITH THIS DYNAMIC SYSTEM...AND OUR FCST REFLECTS THIS. DO NOT XPCT MUCH PCPN BEFORE 18Z...WITH THE HEAVIEST RAIN LIKELY TO FALL VERY LATE AFTN/EVNG. WE EXPANDED THE FFA TO INCLUDE THE ENTIRE FCST AREA...MAIN THREAT BEING +RA AND FLASH FLOODING...AS MDLS ARE SHIFTING THE HEAVY PCPN AXIS FURTHER TO THE WEST. WE STARTED THE FLOOD WATCH AT 00Z EXPECTING THAT ANY HYDRO ISSUES WILL BE AFTER THIS TIME...BUT DAY SHIFT MAY HAVE TO MOVE UP THE START TIME IF PCPN WORKS IN EARLIER THAN XPCTD. ATTM WE XPCT RAINFALL TO AVG SOMEWHERE BETWEEN 1 AND 2 INCHES....LCLY HIER AMTS IN THE SRLY UPSLOPE FAVORED AREAS...LOWEST AMTS PRBLY IN THE LAKE PLAIN. ADDED TSRA TO THE MIX THIS AFTN/EVNG GIVEN WHAT`S BEEN OCCURRING UPSTREAM AND FCST SI`S FROM 0 TO -2. STRONG DYNAMICS IN ALMOST ANY FIELD YOU LOOK AT...INCLUDING IMPRSV UPR LVL DVRGNC ASSCD WITH THE RR QUAD OF AN UPR LVL JET COUPLED WITH STRONG LOW LVL FNTL CONVERGENCE SO CAT POPS CONTINUE TO LOOK GOOD. STEADIER RAINS WILL END LATER TNGT FROM W TO E...PSBLY MIXING WITH -SHSN TWDS DAYBREAK. POTNL FOR SOME VERY GUSTY WINDS WITH ANY CONVECTION THAT DVLPS NEAR/ALONG THE FNT. GIVEN THIS AND THE STRONG WINDS XPCTD BEHIND THE CDFNT ON THU...WE ISSUED A HIGH WIND WATCH FOR THE ENTIRE RGN. RECORD TEMPS FOR TDA INCLUDE 54F AT SYR (2006/1914), 52 AT BGM (1974), AND 66 AT AVP (1947). SYR AND BGM RECORDS ARE GONERS. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... XPCT STRONG WINDS ON THU. NAM/GFS MOS GDNC SHOWING SUSTAINED 25 TO 30 WHICH IS ONE OF THE BETTER INDICATORS SUGGESTING WARNING CRITERIA WINDS ALONG THE LAKE PLAIN. ISALLOBARIC FIELDS ALSO MORE IMPRSV THAN PREV WARNING/ADVISORY EVENT. POTNL FOR WARNING CRITERIA SPCLY ACRS THE LAKE PLAIN AND PSBLY ADJACENT COUNTIES...WITH AN ADVISORY APPEARING LIKELY FOR THE REMAINDER OF THE CWA. AS COLDER AIR WORKS IN ON THU...LES WILL DVLP EAST OF LAKE ONTARIO. PROFILES AND TRAJECTORIES LOOK FVRBL THU AFTN INTO THU NGT FOR SIG ACCUMS AS 850 TEMPS FALL TO -18C...SO AN LES WATCH WAS ISSUED. THIS ACTIVITY IS XPCTD TO DROP SWD LATE THU NGT ON 290-300 FLOW INTO ONON/MAD/SRN ONEIDA. THIS BAND MAY LIFT BACK NWD ON FRI NGT AS LOW LVL FLOW BCMS SWLY AHEAD OF THE NXT CLIPPER. && .LONG TERM /SATURDAY THROUGH TUESDAY/... LK EFFECT SNOW STARTING OFF PD ACRS FAR NRN NY WL TRANSITION NORTH OF THE REGION BY 06Z SATURDAY AS SFC RIDGE NOSES INTO AREA. WK UL TROF WL MV THRU SAT AFTN WITH EC BEING STRONGEST WITH VORT MAX AND GFS WEAKER. THEREFORE HV GONE WITH ONLY CHC POPS AT THIS TIME PER HPC GUIDANCE. POPS WL INCREASE SAT NGT AND SUN AS ANOTHER WV AND ASSOC SFC LOW DROPS THRU THE CWA THO ONLY TO BTWN 40-50%. 12Z GUIDANCE HAS COME INTO BETTER AGREEMENT WITH WV DROPPING INTO NERN U.S. AND DVLPNG SFC LOPRES SUN AFTN/EVNG SOMEWHERE IN THE GULF OF MAINE. ENERGY WL LKLY NOT TRANSFER OFF THE COAST QUICKLY ENUF TO GIVE US A THREAT FOR WIDESPREAD SNOW FOR EARLY NEXT WEEK. TEMPS DRG THE EXTNDD PORTION WL SETTLE OUT CLOSE TO SEASONAL VALUES. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... 12Z WED UPDATE... ONE OF THE MAIN AVIATION IMPACTS THE NEXT 12-18 HRS WILL BE LLWS...AS A VERY STG LOW-LVL JET DVLPS OVER THE RGN...WITH AN INVERSION ALSO IN PLACE IN THE LWST 2K FT...TO KEEP THE STGST WINDS JUST OFF THE SFC. THIS HAZARD WAS CARRIED AT ALL SITES. THERE IS SOME PSBLTY THAT WARMING SFC TEMPS THIS AFTN WILL BE ENOUGH TO ERODE THE INVERSION...AND BRING STG GUSTY WINDS (35-40 KT) ALL THE WAY TO THE SFC. ALTHOUGH WE FEEL THIS IS A LOW PROB OCCURRENCE...KSYR AND KBGM MAY BE THE MOST PROBABLE SITES FOR THIS (DOWNSLOPING SRLY FLOW AT KSYR AND ADDED ELEVATION AT KBGM). SUCH TRENDS WILL OBVIOUSLY BE WATCHED CLOSELY THROUGHOUT THE DAY. EARLY THIS MRNG...SOME LWR CLDS AND LGT FOG COULD OCNLY FLOAT THROUGH AT KBGM/KAVP. OTHERWISE...MAINLY VFR SHOULD PREVAIL INTO EARLY AFTN. FROM 19-22Z ONWARD THROUGH THE EVE HRS...AS THE MAIN COLD FRNTL BNDRY SLOWLY APPROACHES...RAIN SHOULD BECOME STEADIER IN NATURE...WITH PREVAILING MVFR CONDS. EMBEDDED CONVECTIVE ELEMENTS ARE CERTAINLY NOT OUT OF THE QUESTION...GIVEN THE STRENGTH OF THIS SYSTEM...AND THE UNSEASONABLE WARMTH IN PLACE. HOWEVER...WE DON`T FEEL CONFIDENT ENOUGH TO INSERT THUNDER OR EXCESSIVE WIND GUSTS (40+ KT) ATTM. ONCE AGN...RADAR TRENDS WILL BE CLOSELY MONITORED THROUGHOUT THE DAY. FROPA SHOULD OCCUR FM 06-09Z THU...WITH AN ABRUPT WIND SHIFT TO WRLY...AND QUITE AN INCREASE IN THE WINDS AS WELL (GUSTS OF 35-45 KT). .OUTLOOK... THU/FRI/SAT/SUN...OCNL MVFR TO IFR RESTRICTIONS...IN SHSN. && .HYDROLOGY... CONSENSUS OF MODEL AND MAN MADE GUID PROGS PUTS 1 TO UP TO 2.5 INCHES WITH THE HEAVIEST RAIN AXIS FURTHER WEST ACROSS THE FINGER LAKES AND CHEMUNG BASINS OF NY. WILL HAVE TWO BATCHES WITH THE INITIAL BATCH ALREADY IN WRN PA AND WRN NY NOW. THIS FIRST BATCH MOVES QUICKLY THROUGH THIS AFTN. RAINFALL THIS AFTN UP TO HALF AN INCH. QUICK RESPONSE ON STREAMS BUT NO FLOODING INITIALLY. THE COLD FRONT WILL COME THROUGH LATE EVE AND EARLY MORNING WITH MORE HEAVY RAIN. ANOTHER QUICK INCH IN LESS THAN 6 HOURS WHICH WILL BE MOSTLY RUNOFF. STREAMS AND RIVERS WILL RESPOND QUICKLY. FLASH FLOODING POSSIBLE...FOLLOWED BY MINOR RIVER FLOODING. FLOOD WATCH CONTINUES FOR ENTIRE CWA STARTING AT 4 PM INTO THURSDAY MORNING. RIVER FLOOD WARNINGS JUST ISSUED FOR WEST BRANCH DELAWARE RIVER AT WALTON TIOUGHNIOGA RIVER AT CORTLAND CHENANGO RIVER AT SHERBURNE SUSQUEHANNA RIVER AT VESTAL SUSQUEHANNA RIVER AT WAVERLY/SAYRE SUSQUEHANNA RIVER AT TOWANDA SUSQUEHANNA RIVER AT MESHOPPEN SUSQUEHANNA RIVER NEAR WILKES-BARRE && .BGM WATCHES/WARNINGS/ADVISORIES... PA...FLOOD WATCH FROM 4 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR PAZ038>040-043-044-047-048-072. HIGH WIND WATCH FROM 7 PM EST THIS EVENING THROUGH THURSDAY EVENING FOR PAZ038>040-043-044-047-048-072. NY...FLOOD WATCH FROM 4 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR NYZ009-015>018-022>025-036-037-044>046- 055>057-062. HIGH WIND WATCH FROM 7 PM EST THIS EVENING THROUGH THURSDAY EVENING FOR NYZ009-015>018-022>025-036-037-044>046- 055>057-062. LAKE EFFECT SNOW WATCH FROM THURSDAY MORNING THROUGH FRIDAY MORNING FOR NYZ009. && $$ SYNOPSIS... NEAR TERM...PVN SHORT TERM... LONG TERM...PVN AVIATION...MLJ HYDROLOGY...
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
858 AM EST WED JAN 30 2013 .SYNOPSIS... UNSEASONABLY WARM AIR WILL OVERSPREAD THE REGION TODAY IN ADVANCE OF A STRONG COLD FRONT. SHOWERS AND SCATTERED THUNDERSTORMS WILL DEVELOP THIS AFTERNOON IN THIS MOIST AIR MASS...AND THE RAIN WILL BE HEAVY AT TIMES. COLDER AIR BEHIND THE FRONT WILL TRIGGER LAKE EFFECT SNOWS ACROSS CENTRAL NEW YORK ON THURSDAY AND THURSDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... 9 AM UPDATE... YET ANOTHER UPDATE TO BUMP TEMPS DOWN AT KAVP WITH SENSOR READING AROUND 4 DEGREES TOO WARM. NO OTHER CHGS NEEDED AT THIS TIME AS A MAJOR WX EVENT IS IMPENDING FOR TONIGHT. 730 AM UPDATE... QUICK UPDATE TO BUMP CURRENT TEMPS UP IN WYOMING/LACKAWANNA VLYS AS KAVP IS NOW UP TO 62F. MESONET SITES IN THAT AREA ARE CURRENTLY IN THE MID-50S THUS NOT OUT OF THE QUESTION THAT SCRANTON WILKES- BARRE AIRPORT IS IN THE LOW 60S AS IT SITS AROUND 1000 FEET UP AND WITH STRONG INVERSION IN PLACE PER KALY/KOKX 12Z RAOBS. 630 AM UPDATE...MINOR T/TD TWEEKS IN THE NEAR TERM...RAISING MAXES BY A FEW DEG MAINLY FINGER LAKES AND CNTRL SRN TIER. ALSO ADDED PC SKIES FOR PARTS OF THE RGN THIS MRNG. CRUDE XTRAPOLATION OF LEADING PCPN SHIELD INDICATES ARRIVAL TIME ARND 1730Z INTO WRN STEUBEN. WE`LL SEE IF THIS HOLDS. NO OTHER CHGS. PREV BLO... 510 AM UPDATE...BUMPED UP START TIME OF THE FLOOD WATCH TO 21Z. PREV BLO.. LOTS TO LOOK AT THIS FCST PCKG. MAIN FOCUS IS ON THE APRCHNG CDFNT AND DIGGING UPR TROF...WHICH WILL BRING A ROUND OF +RA AND WIND TO THE RGN STARTING THIS AFTERNOON INTO THE OVRNGT HRS. THERE IS TREMENDOUS BUST POTNL WITH THIS FCST...STARTING OFF WITH MAX TEMPS TDA. WE ARE FCSTNG MAXES INTO THE LOWER 60S MAINLY W OF I-81...BUT IF WE GET SOME BREAKS OF SUN LATER THIS MRNG THIS FCST WILL BE ON THE COOL SIDE. WE ALSO NOTE THAT TEMPS ARE CRNTLY (AS OF 330 AM) A60 OVER MOST OF OH. ATTM WE PLAYED IT CLOSE TO THE VEST...WITH EXPECTATION THAT ANY SUNSHINE WILL BE LIMITED. BUT IT IS SOMETHING TO WATCH. MDLS HAVE BEEN LEANING SLOWER WITH THIS DYNAMIC SYSTEM...AND OUR FCST REFLECTS THIS. DO NOT XPCT MUCH PCPN BEFORE 18Z...WITH THE HEAVIEST RAIN LIKELY TO FALL VERY LATE AFTN/EVNG. WE EXPANDED THE FFA TO INCLUDE THE ENTIRE FCST AREA...MAIN THREAT BEING +RA AND FLASH FLOODING...AS MDLS ARE SHIFTING THE HEAVY PCPN AXIS FURTHER TO THE WEST. WE STARTED THE FLOOD WATCH AT 00Z EXPECTING THAT ANY HYDRO ISSUES WILL BE AFTER THIS TIME...BUT DAY SHIFT MAY HAVE TO MOVE UP THE START TIME IF PCPN WORKS IN EARLIER THAN XPCTD. ATTM WE XPCT RAINFALL TO AVG SOMEWHERE BETWEEN 1 AND 2 INCHES....LCLY HIER AMTS IN THE SRLY UPSLOPE FAVORED AREAS...LOWEST AMTS PRBLY IN THE LAKE PLAIN. ADDED TSRA TO THE MIX THIS AFTN/EVNG GIVEN WHAT`S BEEN OCCURRING UPSTREAM AND FCST SI`S FROM 0 TO -2. STRONG DYNAMICS IN ALMOST ANY FIELD YOU LOOK AT...INCLUDING IMPRSV UPR LVL DVRGNC ASSCD WITH THE RR QUAD OF AN UPR LVL JET COUPLED WITH STRONG LOW LVL FNTL CONVERGENCE SO CAT POPS CONTINUE TO LOOK GOOD. STEADIER RAINS WILL END LATER TNGT FROM W TO E...PSBLY MIXING WITH -SHSN TWDS DAYBREAK. POTNL FOR SOME VERY GUSTY WINDS WITH ANY CONVECTION THAT DVLPS NEAR/ALONG THE FNT. GIVEN THIS AND THE STRONG WINDS XPCTD BEHIND THE CDFNT ON THU...WE ISSUED A HIGH WIND WATCH FOR THE ENTIRE RGN. RECORD TEMPS FOR TDA INCLUDE 54F AT SYR (2006/1914), 52 AT BGM (1974), AND 66 AT AVP (1947). SYR AND BGM RECORDS ARE GONERS. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... XPCT STRONG WINDS ON THU. NAM/GFS MOS GDNC SHOWING SUSTAINED 25 TO 30 WHICH IS ONE OF THE BETTER INDICATORS SUGGESTING WARNING CRITERIA WINDS ALONG THE LAKE PLAIN. ISALLOBARIC FIELDS ALSO MORE IMPRSV THAN PREV WARNING/ADVISORY EVENT. POTNL FOR WARNING CRITERIA SPCLY ACRS THE LAKE PLAIN AND PSBLY ADJACENT COUNTIES...WITH AN ADVISORY APPEARING LIKELY FOR THE REMAINDER OF THE CWA. AS COLDER AIR WORKS IN ON THU...LES WILL DVLP EAST OF LAKE ONTARIO. PROFILES AND TRAJECTORIES LOOK FVRBL THU AFTN INTO THU NGT FOR SIG ACCUMS AS 850 TEMPS FALL TO -18C...SO AN LES WATCH WAS ISSUED. THIS ACTIVITY IS XPCTD TO DROP SWD LATE THU NGT ON 290-300 FLOW INTO ONON/MAD/SRN ONEIDA. THIS BAND MAY LIFT BACK NWD ON FRI NGT AS LOW LVL FLOW BCMS SWLY AHEAD OF THE NXT CLIPPER. && .LONG TERM /SATURDAY THROUGH TUESDAY/... LK EFFECT SNOW STARTING OFF PD ACRS FAR NRN NY WL TRANSITION NORTH OF THE REGION BY 06Z SATURDAY AS SFC RIDGE NOSES INTO AREA. WK UL TROF WL MV THRU SAT AFTN WITH EC BEING STRONGEST WITH VORT MAX AND GFS WEAKER. THEREFORE HV GONE WITH ONLY CHC POPS AT THIS TIME PER HPC GUIDANCE. POPS WL INCREASE SAT NGT AND SUN AS ANOTHER WV AND ASSOC SFC LOW DROPS THRU THE CWA THO ONLY TO BTWN 40-50%. 12Z GUIDANCE HAS COME INTO BETTER AGREEMENT WITH WV DROPPING INTO NERN U.S. AND DVLPNG SFC LOPRES SUN AFTN/EVNG SOMEWHERE IN THE GULF OF MAINE. ENERGY WL LKLY NOT TRANSFER OFF THE COAST QUICKLY ENUF TO GIVE US A THREAT FOR WIDESPREAD SNOW FOR EARLY NEXT WEEK. TEMPS DRG THE EXTNDD PORTION WL SETTLE OUT CLOSE TO SEASONAL VALUES. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... 12Z WED UPDATE... ONE OF THE MAIN AVIATION IMPACTS THE NEXT 12-18 HRS WILL BE LLWS...AS A VERY STG LOW-LVL JET DVLPS OVER THE RGN...WITH AN INVERSION ALSO IN PLACE IN THE LWST 2K FT...TO KEEP THE STGST WINDS JUST OFF THE SFC. THIS HAZARD WAS CARRIED AT ALL SITES. THERE IS SOME PSBLTY THAT WARMING SFC TEMPS THIS AFTN WILL BE ENOUGH TO ERODE THE INVERSION...AND BRING STG GUSTY WINDS (35-40 KT) ALL THE WAY TO THE SFC. ALTHOUGH WE FEEL THIS IS A LOW PROB OCCURRENCE...KSYR AND KBGM MAY BE THE MOST PROBABLE SITES FOR THIS (DOWNSLOPING SRLY FLOW AT KSYR AND ADDED ELEVATION AT KBGM). SUCH TRENDS WILL OBVIOUSLY BE WATCHED CLOSELY THROUGHOUT THE DAY. EARLY THIS MRNG...SOME LWR CLDS AND LGT FOG COULD OCNLY FLOAT THROUGH AT KBGM/KAVP. OTHERWISE...MAINLY VFR SHOULD PREVAIL INTO EARLY AFTN. FROM 19-22Z ONWARD THROUGH THE EVE HRS...AS THE MAIN COLD FRNTL BNDRY SLOWLY APPROACHES...RAIN SHOULD BECOME STEADIER IN NATURE...WITH PREVAILING MVFR CONDS. EMBEDDED CONVECTIVE ELEMENTS ARE CERTAINLY NOT OUT OF THE QUESTION...GIVEN THE STRENGTH OF THIS SYSTEM...AND THE UNSEASONABLE WARMTH IN PLACE. HOWEVER...WE DON`T FEEL CONFIDENT ENOUGH TO INSERT THUNDER OR EXCESSIVE WIND GUSTS (40+ KT) ATTM. ONCE AGN...RADAR TRENDS WILL BE CLOSELY MONITORED THROUGHOUT THE DAY. FROPA SHOULD OCCUR FM 06-09Z THU...WITH AN ABRUPT WIND SHIFT TO WRLY...AND QUITE AN INCREASE IN THE WINDS AS WELL (GUSTS OF 35-45 KT). .OUTLOOK... THU/FRI/SAT/SUN...OCNL MVFR TO IFR RESTRICTIONS...IN SHSN. && .HYDROLOGY... CONSENSUS OF MODEL AND MAN MADE GUID PROGS PUTS UP TO 2 INCHES OF QPF OVER THE WRN CATS AND PARTS OF NEPA. THIS SEEMS RATHER HIGH FOR A FAST MVG COLD FNT BUT WE DO HAVE A WV DVLPG ALONG THE FNT THAT DVLPS GOOD LL CONV THAT IN TURN BRINGS A PD OF SLY OR SELY INFLOW...MAINLY INTO THE CATS. IF WE SEE THE WORST CASE SCENARIO THERE WLD BE SOME MINOR FLOOD PRBLMS ON THE MAIN RVRS. OF BIGGER CNCRN TO ME WLD BE THE SMALLER STREAMS WHERE THIS PTNL RAIN WLD FALL OVER A RELATIVELY SMALL WINDOW...ABT 6 HRS. OTR FACTOR TO ALWAYS CONSIDER IS THE ONGOING PRBLM WITH FLOOD DAMAGED STREAM BEDS IN THE AREA FROM PAST EVENTS. WILL ISSUE A GENERIC FLOOD WATCH FOR THE WESTERN CATS AND MUCH OF NEPA TO CVR THE RAIN AND FLOOD PTNL. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...FLOOD WATCH FROM 4 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR PAZ038>040-043-044-047-048-072. HIGH WIND WATCH FROM 7 PM EST THIS EVENING THROUGH THURSDAY EVENING FOR PAZ038>040-043-044-047-048-072. NY...FLOOD WATCH FROM 4 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR NYZ009-015>018-022>025-036-037-044>046- 055>057-062. HIGH WIND WATCH FROM 7 PM EST THIS EVENING THROUGH THURSDAY EVENING FOR NYZ009-015>018-022>025-036-037-044>046- 055>057-062. LAKE EFFECT SNOW WATCH FROM THURSDAY MORNING THROUGH FRIDAY MORNING FOR NYZ009. && $$ SYNOPSIS... NEAR TERM...PVN SHORT TERM... LONG TERM...PVN AVIATION...MLJ HYDROLOGY...
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
738 AM EST WED JAN 30 2013 .SYNOPSIS... UNSEASONABLY WARM AIR WILL OVERSPREAD THE REGION TODAY IN ADVANCE OF A STRONG COLD FRONT. SHOWERS AND SCATTERED THUNDERSTORMS WILL DEVELOP THIS AFTERNOON IN THIS MOIST AIR MASS...AND THE RAIN WILL BE HEAVY AT TIMES. COLDER AIR BEHIND THE FRONT WILL TRIGGER LAKE EFFECT SNOWS ACROSS CENTRAL NEW YORK ON THURSDAY AND THURSDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... 730 AM UPDATE... QUICK UPDATE TO BUMP CURRENT TEMPS UP IN WYOMING/LACKAWANNA VLYS AS KAVP IS NOW UP TO 62F. MESONET SITES IN THAT AREA ARE CURRENTLY IN THE MID-50S THUS NOT OUT OF THE QUESTION THAT SCRANTON WILKES- BARRE AIRPORT IS IN THE LOW 60S AS IT SITS AROUND 1000 FEET UP AND WITH STRONG INVERSION IN PLACE PER KALY/KOKX 12Z RAOBS. 630 AM UPDATE...MINOR T/TD TWEEKS IN THE NEAR TERM...RAISING MAXES BY A FEW DEG MAINLY FINGER LAKES AND CNTRL SRN TIER. ALSO ADDED PC SKIES FOR PARTS OF THE RGN THIS MRNG. CRUDE XTRAPOLATION OF LEADING PCPN SHIELD INDICATES ARRIVAL TIME ARND 1730Z INTO WRN STEUBEN. WE`LL SEE IF THIS HOLDS. NO OTHER CHGS. PREV BLO... 510 AM UPDATE...BUMPED UP START TIME OF THE FLOOD WATCH TO 21Z. PREV BLO.. LOTS TO LOOK AT THIS FCST PCKG. MAIN FOCUS IS ON THE APRCHNG CDFNT AND DIGGING UPR TROF...WHICH WILL BRING A ROUND OF +RA AND WIND TO THE RGN STARTING THIS AFTERNOON INTO THE OVRNGT HRS. THERE IS TREMENDOUS BUST POTNL WITH THIS FCST...STARTING OFF WITH MAX TEMPS TDA. WE ARE FCSTNG MAXES INTO THE LOWER 60S MAINLY W OF I-81...BUT IF WE GET SOME BREAKS OF SUN LATER THIS MRNG THIS FCST WILL BE ON THE COOL SIDE. WE ALSO NOTE THAT TEMPS ARE CRNTLY (AS OF 330 AM) A60 OVER MOST OF OH. ATTM WE PLAYED IT CLOSE TO THE VEST...WITH EXPECTATION THAT ANY SUNSHINE WILL BE LIMITED. BUT IT IS SOMETHING TO WATCH. MDLS HAVE BEEN LEANING SLOWER WITH THIS DYNAMIC SYSTEM...AND OUR FCST REFLECTS THIS. DO NOT XPCT MUCH PCPN BEFORE 18Z...WITH THE HEAVIEST RAIN LIKELY TO FALL VERY LATE AFTN/EVNG. WE EXPANDED THE FFA TO INCLUDE THE ENTIRE FCST AREA...MAIN THREAT BEING +RA AND FLASH FLOODING...AS MDLS ARE SHIFTING THE HEAVY PCPN AXIS FURTHER TO THE WEST. WE STARTED THE FLOOD WATCH AT 00Z EXPECTING THAT ANY HYDRO ISSUES WILL BE AFTER THIS TIME...BUT DAY SHIFT MAY HAVE TO MOVE UP THE START TIME IF PCPN WORKS IN EARLIER THAN XPCTD. ATTM WE XPCT RAINFALL TO AVG SOMEWHERE BETWEEN 1 AND 2 INCHES....LCLY HIER AMTS IN THE SRLY UPSLOPE FAVORED AREAS...LOWEST AMTS PRBLY IN THE LAKE PLAIN. ADDED TSRA TO THE MIX THIS AFTN/EVNG GIVEN WHAT`S BEEN OCCURRING UPSTREAM AND FCST SI`S FROM 0 TO -2. STRONG DYNAMICS IN ALMOST ANY FIELD YOU LOOK AT...INCLUDING IMPRSV UPR LVL DVRGNC ASSCD WITH THE RR QUAD OF AN UPR LVL JET COUPLED WITH STRONG LOW LVL FNTL CONVERGENCE SO CAT POPS CONTINUE TO LOOK GOOD. STEADIER RAINS WILL END LATER TNGT FROM W TO E...PSBLY MIXING WITH -SHSN TWDS DAYBREAK. POTNL FOR SOME VERY GUSTY WINDS WITH ANY CONVECTION THAT DVLPS NEAR/ALONG THE FNT. GIVEN THIS AND THE STRONG WINDS XPCTD BEHIND THE CDFNT ON THU...WE ISSUED A HIGH WIND WATCH FOR THE ENTIRE RGN. RECORD TEMPS FOR TDA INCLUDE 54F AT SYR (2006/1914), 52 AT BGM (1974), AND 66 AT AVP (1947). SYR AND BGM RECORDS ARE GONERS. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... XPCT STRONG WINDS ON THU. NAM/GFS MOS GDNC SHOWING SUSTAINED 25 TO 30 WHICH IS ONE OF THE BETTER INDICATORS SUGGESTING WARNING CRITERIA WINDS ALONG THE LAKE PLAIN. ISALLOBARIC FIELDS ALSO MORE IMPRSV THAN PREV WARNING/ADVISORY EVENT. POTNL FOR WARNING CRITERIA SPCLY ACRS THE LAKE PLAIN AND PSBLY ADJACENT COUNTIES...WITH AN ADVISORY APPEARING LIKELY FOR THE REMAINDER OF THE CWA. AS COLDER AIR WORKS IN ON THU...LES WILL DVLP EAST OF LAKE ONTARIO. PROFILES AND TRAJECTORIES LOOK FVRBL THU AFTN INTO THU NGT FOR SIG ACCUMS AS 850 TEMPS FALL TO -18C...SO AN LES WATCH WAS ISSUED. THIS ACTIVITY IS XPCTD TO DROP SWD LATE THU NGT ON 290-300 FLOW INTO ONON/MAD/SRN ONEIDA. THIS BAND MAY LIFT BACK NWD ON FRI NGT AS LOW LVL FLOW BCMS SWLY AHEAD OF THE NXT CLIPPER. && .LONG TERM /SATURDAY THROUGH TUESDAY/... LK EFFECT SNOW STARTING OFF PD ACRS FAR NRN NY WL TRANSITION NORTH OF THE REGION BY 06Z SATURDAY AS SFC RIDGE NOSES INTO AREA. WK UL TROF WL MV THRU SAT AFTN WITH EC BEING STRONGEST WITH VORT MAX AND GFS WEAKER. THEREFORE HV GONE WITH ONLY CHC POPS AT THIS TIME PER HPC GUIDANCE. POPS WL INCREASE SAT NGT AND SUN AS ANOTHER WV AND ASSOC SFC LOW DROPS THRU THE CWA THO ONLY TO BTWN 40-50%. 12Z GUIDANCE HAS COME INTO BETTER AGREEMENT WITH WV DROPPING INTO NERN U.S. AND DVLPNG SFC LOPRES SUN AFTN/EVNG SOMEWHERE IN THE GULF OF MAINE. ENERGY WL LKLY NOT TRANSFER OFF THE COAST QUICKLY ENUF TO GIVE US A THREAT FOR WIDESPREAD SNOW FOR EARLY NEXT WEEK. TEMPS DRG THE EXTNDD PORTION WL SETTLE OUT CLOSE TO SEASONAL VALUES. && .AVIATION /13Z WEDNESDAY THROUGH SUNDAY/... 12Z WED UPDATE... ONE OF THE MAIN AVIATION IMPACTS THE NEXT 12-18 HRS WILL BE LLWS...AS A VERY STG LOW-LVL JET DVLPS OVER THE RGN...WITH AN INVERSION ALSO IN PLACE IN THE LWST 2K FT...TO KEEP THE STGST WINDS JUST OFF THE SFC. THIS HAZARD WAS CARRIED AT ALL SITES. THERE IS SOME PSBLTY THAT WARMING SFC TEMPS THIS AFTN WILL BE ENOUGH TO ERODE THE INVERSION...AND BRING STG GUSTY WINDS (35-40 KT) ALL THE WAY TO THE SFC. ALTHOUGH WE FEEL THIS IS A LOW PROB OCCURRENCE...KSYR AND KBGM MAY BE THE MOST PROBABLE SITES FOR THIS (DOWNSLOPING SRLY FLOW AT KSYR AND ADDED ELEVATION AT KBGM). SUCH TRENDS WILL OBVIOUSLY BE WATCHED CLOSELY THROUGHOUT THE DAY. EARLY THIS MRNG...SOME LWR CLDS AND LGT FOG COULD OCNLY FLOAT THROUGH AT KBGM/KAVP. OTHERWISE...MAINLY VFR SHOULD PREVAIL INTO EARLY AFTN. FROM 19-22Z ONWARD THROUGH THE EVE HRS...AS THE MAIN COLD FRNTL BNDRY SLOWLY APPROACHES...RAIN SHOULD BECOME STEADIER IN NATURE...WITH PREVAILING MVFR CONDS. EMBEDDED CONVECTIVE ELEMENTS ARE CERTAINLY NOT OUT OF THE QUESTION...GIVEN THE STRENGTH OF THIS SYSTEM...AND THE UNSEASONABLE WARMTH IN PLACE. HOWEVER...WE DON`T FEEL CONFIDENT ENOUGH TO INSERT THUNDER OR EXCESSIVE WIND GUSTS (40+ KT) ATTM. ONCE AGN...RADAR TRENDS WILL BE CLOSELY MONITORED THROUGHOUT THE DAY. FROPA SHOULD OCCUR FM 06-09Z THU...WITH AN ABRUPT WIND SHIFT TO WRLY...AND QUITE AN INCREASE IN THE WINDS AS WELL (GUSTS OF 35-45 KT). .OUTLOOK... THU/FRI/SAT/SUN...OCNL MVFR TO IFR RESTRICTIONS...IN SHSN. && .HYDROLOGY... CONSENSUS OF MODEL AND MAN MADE GUID PROGS PUTS UP TO 2 INCHES OF QPF OVER THE WRN CATS AND PARTS OF NEPA. THIS SEEMS RATHER HIGH FOR A FAST MVG COLD FNT BUT WE DO HAVE A WV DVLPG ALONG THE FNT THAT DVLPS GOOD LL CONV THAT IN TURN BRINGS A PD OF SLY OR SELY INFLOW...MAINLY INTO THE CATS. IF WE SEE THE WORST CASE SCENARIO THERE WLD BE SOME MINOR FLOOD PRBLMS ON THE MAIN RVRS. OF BIGGER CNCRN TO ME WLD BE THE SMALLER STREAMS WHERE THIS PTNL RAIN WLD FALL OVER A RELATIVELY SMALL WINDOW...ABT 6 HRS. OTR FACTOR TO ALWAYS CONSIDER IS THE ONGOING PRBLM WITH FLOOD DAMAGED STREAM BEDS IN THE AREA FROM PAST EVENTS. WILL ISSUE A GENERIC FLOOD WATCH FOR THE WESTERN CATS AND MUCH OF NEPA TO CVR THE RAIN AND FLOOD PTNL. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...FLOOD WATCH FROM 4 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR PAZ038>040-043-044-047-048-072. HIGH WIND WATCH FROM 7 PM EST THIS EVENING THROUGH THURSDAY EVENING FOR PAZ038>040-043-044-047-048-072. NY...FLOOD WATCH FROM 4 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR NYZ009-015>018-022>025-036-037-044>046- 055>057-062. HIGH WIND WATCH FROM 7 PM EST THIS EVENING THROUGH THURSDAY EVENING FOR NYZ009-015>018-022>025-036-037-044>046- 055>057-062. LAKE EFFECT SNOW WATCH FROM THURSDAY MORNING THROUGH FRIDAY MORNING FOR NYZ009. && $$ SYNOPSIS... NEAR TERM...PVN SHORT TERM... LONG TERM...PVN AVIATION...MLJ HYDROLOGY...
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
650 AM EST WED JAN 30 2013 .SYNOPSIS... UNSEASONABLY WARM AIR WILL OVERSPREAD THE REGION TODAY IN ADVANCE OF A STRONG COLD FRONT. SHOWERS AND SCATTERED THUNDERSTORMS WILL DEVELOP THIS AFTERNOON IN THIS MOIST AIR MASS...AND THE RAIN WILL BE HEAVY AT TIMES. COLDER AIR BEHIND THE FRONT WILL TRIGGER LAKE EFFECT SNOWS ACROSS CENTRAL NEW YORK ON THURSDAY AND THURSDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... 630 AM UPDATE...MINOR T/TD TWEEKS IN THE NEAR TERM...RAISING MAXES BY A FEW DEG MAINLY FINGER LAKES AND CNTRL SRN TIER. ALSO ADDED PC SKIES FOR PARTS OF THE RGN THIS MRNG. CRUDE XTRAPOLATION OF LEADING PCPN SHIELD INDICATES ARRIVAL TIME ARND 1730Z INTO WRN STEUBEN. WE`LL SEE IF THIS HOLDS. NO OTHER CHGS. PREV BLO... 510 AM UPDATE...BUMPED UP START TIME OF THE FLOOD WATCH TO 21Z. PREV BLO.. LOTS TO LOOK AT THIS FCST PCKG. MAIN FOCUS IS ON THE APRCHNG CDFNT AND DIGGING UPR TROF...WHICH WILL BRING A ROUND OF +RA AND WIND TO THE RGN STARTING THIS AFTERNOON INTO THE OVRNGT HRS. THERE IS TREMENDOUS BUST POTNL WITH THIS FCST...STARTING OFF WITH MAX TEMPS TDA. WE ARE FCSTNG MAXES INTO THE LOWER 60S MAINLY W OF I-81...BUT IF WE GET SOME BREAKS OF SUN LATER THIS MRNG THIS FCST WILL BE ON THE COOL SIDE. WE ALSO NOTE THAT TEMPS ARE CRNTLY (AS OF 330 AM) A60 OVER MOST OF OH. ATTM WE PLAYED IT CLOSE TO THE VEST...WITH EXPECTATION THAT ANY SUNSHINE WILL BE LIMITED. BUT IT IS SOMETHING TO WATCH. MDLS HAVE BEEN LEANING SLOWER WITH THIS DYNAMIC SYSTEM...AND OUR FCST REFLECTS THIS. DO NOT XPCT MUCH PCPN BEFORE 18Z...WITH THE HEAVIEST RAIN LIKELY TO FALL VERY LATE AFTN/EVNG. WE EXPANDED THE FFA TO INCLUDE THE ENTIRE FCST AREA...MAIN THREAT BEING +RA AND FLASH FLOODING...AS MDLS ARE SHIFTING THE HEAVY PCPN AXIS FURTHER TO THE WEST. WE STARTED THE FLOOD WATCH AT 00Z EXPECTING THAT ANY HYDRO ISSUES WILL BE AFTER THIS TIME...BUT DAY SHIFT MAY HAVE TO MOVE UP THE START TIME IF PCPN WORKS IN EARLIER THAN XPCTD. ATTM WE XPCT RAINFALL TO AVG SOMEWHERE BETWEEN 1 AND 2 INCHES....LCLY HIER AMTS IN THE SRLY UPSLOPE FAVORED AREAS...LOWEST AMTS PRBLY IN THE LAKE PLAIN. ADDED TSRA TO THE MIX THIS AFTN/EVNG GIVEN WHAT`S BEEN OCCURRING UPSTREAM AND FCST SI`S FROM 0 TO -2. STRONG DYNAMICS IN ALMOST ANY FIELD YOU LOOK AT...INCLUDING IMPRSV UPR LVL DVRGNC ASSCD WITH THE RR QUAD OF AN UPR LVL JET COUPLED WITH STRONG LOW LVL FNTL CONVERGENCE SO CAT POPS CONTINUE TO LOOK GOOD. STEADIER RAINS WILL END LATER TNGT FROM W TO E...PSBLY MIXING WITH -SHSN TWDS DAYBREAK. POTNL FOR SOME VERY GUSTY WINDS WITH ANY CONVECTION THAT DVLPS NEAR/ALONG THE FNT. GIVEN THIS AND THE STRONG WINDS XPCTD BEHIND THE CDFNT ON THU...WE ISSUED A HIGH WIND WATCH FOR THE ENTIRE RGN. RECORD TEMPS FOR TDA INCLUDE 54F AT SYR (2006/1914), 52 AT BGM (1974), AND 66 AT AVP (1947). SYR AND BGM RECORDS ARE GONERS. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... XPCT STRONG WINDS ON THU. NAM/GFS MOS GDNC SHOWING SUSTAINED 25 TO 30 WHICH IS ONE OF THE BETTER INDICATORS SUGGESTING WARNING CRITERIA WINDS ALONG THE LAKE PLAIN. ISALLOBARIC FIELDS ALSO MORE IMPRSV THAN PREV WARNING/ADVISORY EVENT. POTNL FOR WARNING CRITERIA SPCLY ACRS THE LAKE PLAIN AND PSBLY ADJACENT COUNTIES...WITH AN ADVISORY APPEARING LIKELY FOR THE REMAINDER OF THE CWA. AS COLDER AIR WORKS IN ON THU...LES WILL DVLP EAST OF LAKE ONTARIO. PROFILES AND TRAJECTORIES LOOK FVRBL THU AFTN INTO THU NGT FOR SIG ACCUMS AS 850 TEMPS FALL TO -18C...SO AN LES WATCH WAS ISSUED. THIS ACTIVITY IS XPCTD TO DROP SWD LATE THU NGT ON 290-300 FLOW INTO ONON/MAD/SRN ONEIDA. THIS BAND MAY LIFT BACK NWD ON FRI NGT AS LOW LVL FLOW BCMS SWLY AHEAD OF THE NXT CLIPPER. && .LONG TERM /SATURDAY THROUGH TUESDAY/... LK EFFECT SNOW STARTING OFF PD ACRS FAR NRN NY WL TRANSITION NORTH OF THE REGION BY 06Z SATURDAY AS SFC RIDGE NOSES INTO AREA. WK UL TROF WL MV THRU SAT AFTN WITH EC BEING STRONGEST WITH VORT MAX AND GFS WEAKER. THEREFORE HV GONE WITH ONLY CHC POPS AT THIS TIME PER HPC GUIDANCE. POPS WL INCREASE SAT NGT AND SUN AS ANOTHER WV AND ASSOC SFC LOW DROPS THRU THE CWA THO ONLY TO BTWN 40-50%. 12Z GUIDANCE HAS COME INTO BETTER AGREEMENT WITH WV DROPPING INTO NERN U.S. AND DVLPNG SFC LOPRES SUN AFTN/EVNG SOMEWHERE IN THE GULF OF MAINE. ENERGY WL LKLY NOT TRANSFER OFF THE COAST QUICKLY ENUF TO GIVE US A THREAT FOR WIDESPREAD SNOW FOR EARLY NEXT WEEK. TEMPS DRG THE EXTNDD PORTION WL SETTLE OUT CLOSE TO SEASONAL VALUES. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... 12Z WED UPDATE... ONE OF THE MAIN AVIATION IMPACTS THE NEXT 12-18 HRS WILL BE LLWS...AS A VERY STG LOW-LVL JET DVLPS OVER THE RGN...WITH AN INVERSION ALSO IN PLACE IN THE LWST 2K FT...TO KEEP THE STGST WINDS JUST OFF THE SFC. THIS HAZARD WAS CARRIED AT ALL SITES. THERE IS SOME PSBLTY THAT WARMING SFC TEMPS THIS AFTN WILL BE ENOUGH TO ERODE THE INVERSION...AND BRING STG GUSTY WINDS (35-40 KT) ALL THE WAY TO THE SFC. ALTHOUGH WE FEEL THIS IS A LOW PROB OCCURRENCE...KSYR AND KBGM MAY BE THE MOST PROBABLE SITES FOR THIS (DOWNSLOPING SRLY FLOW AT KSYR AND ADDED ELEVATION AT KBGM). SUCH TRENDS WILL OBVIOUSLY BE WATCHED CLOSELY THROUGHOUT THE DAY. EARLY THIS MRNG...SOME LWR CLDS AND LGT FOG COULD OCNLY FLOAT THROUGH AT KBGM/KAVP. OTHERWISE...MAINLY VFR SHOULD PREVAIL INTO EARLY AFTN. FROM 19-22Z ONWARD THROUGH THE EVE HRS...AS THE MAIN COLD FRNTL BNDRY SLOWLY APPROACHES...RAIN SHOULD BECOME STEADIER IN NATURE...WITH PREVAILING MVFR CONDS. EMBEDDED CONVECTIVE ELEMENTS ARE CERTAINLY NOT OUT OF THE QUESTION...GIVEN THE STRENGTH OF THIS SYSTEM...AND THE UNSEASONABLE WARMTH IN PLACE. HOWEVER...WE DON`T FEEL CONFIDENT ENOUGH TO INSERT THUNDER OR EXCESSIVE WIND GUSTS (40+ KT) ATTM. ONCE AGN...RADAR TRENDS WILL BE CLOSELY MONITORED THROUGHOUT THE DAY. FROPA SHOULD OCCUR FM 06-09Z THU...WITH AN ABRUPT WIND SHIFT TO WRLY...AND QUITE AN INCREASE IN THE WINDS AS WELL (GUSTS OF 35-45 KT). .OUTLOOK... THU/FRI/SAT/SUN...OCNL MVFR TO IFR RESTRICTIONS...IN SHSN. && .HYDROLOGY... CONSENSUS OF MODEL AND MAN MADE GUID PROGS PUTS UP TO 2 INCHES OF QPF OVER THE WRN CATS AND PARTS OF NEPA. THIS SEEMS RATHER HIGH FOR A FAST MVG COLD FNT BUT WE DO HAVE A WV DVLPG ALONG THE FNT THAT DVLPS GOOD LL CONV THAT IN TURN BRINGS A PD OF SLY OR SELY INFLOW...MAINLY INTO THE CATS. IF WE SEE THE WORST CASE SCENARIO THERE WLD BE SOME MINOR FLOOD PRBLMS ON THE MAIN RVRS. OF BIGGER CNCRN TO ME WLD BE THE SMALLER STREAMS WHERE THIS PTNL RAIN WLD FALL OVER A RELATIVELY SMALL WINDOW...ABT 6 HRS. OTR FACTOR TO ALWAYS CONSIDER IS THE ONGOING PRBLM WITH FLOOD DAMAGED STREAM BEDS IN THE AREA FROM PAST EVENTS. WILL ISSUE A GENERIC FLOOD WATCH FOR THE WESTERN CATS AND MUCH OF NEPA TO CVR THE RAIN AND FLOOD PTNL. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...FLOOD WATCH FROM 4 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR PAZ038>040-043-044-047-048-072. HIGH WIND WATCH FROM THIS EVENING THROUGH THURSDAY EVENING FOR PAZ038>040-043-044-047-048-072. NY...FLOOD WATCH FROM 4 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR NYZ009-015>018-022>025-036-037-044>046- 055>057-062. HIGH WIND WATCH FROM THIS EVENING THROUGH THURSDAY EVENING FOR NYZ009-015>018-022>025-036-037-044>046-055>057-062. LAKE EFFECT SNOW WATCH FROM THURSDAY MORNING THROUGH FRIDAY MORNING FOR NYZ009. && $$ SYNOPSIS... NEAR TERM... SHORT TERM... LONG TERM...PVN AVIATION...MLJ HYDROLOGY...
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
512 AM EST WED JAN 30 2013 .SYNOPSIS... UNSEASONABLY WARM AIR WILL OVERSPREAD THE REGION TODAY IN ADVANCE OF A STRONG COLD FRONT. SHOWERS AND SCATTERED THUNDERSTORMS WILL DEVELOP THIS AFTERNOON IN THIS MOIST AIR MASS...AND THE RAIN WILL BE HEAVY AT TIMES. COLDER AIR BEHIND THE FRONT WILL TRIGGER LAKE EFFECT SNOWS ACROSS CENTRAL NEW YORK ON THURSDAY AND THURSDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... 510 AM UPDATE...BUMPED UP START TIME OF THE FLOOD WATCH TO 21Z. PREV BLO.. LOTS TO LOOK AT THIS FCST PCKG. MAIN FOCUS IS ON THE APRCHNG CDFNT AND DIGGING UPR TROF...WHICH WILL BRING A ROUND OF +RA AND WIND TO THE RGN STARTING THIS AFTERNOON INTO THE OVRNGT HRS. THERE IS TREMENDOUS BUST POTNL WITH THIS FCST...STARTING OFF WITH MAX TEMPS TDA. WE ARE FCSTNG MAXES INTO THE LOWER 60S MAINLY W OF I-81...BUT IF WE GET SOME BREAKS OF SUN LATER THIS MRNG THIS FCST WILL BE ON THE COOL SIDE. WE ALSO NOTE THAT TEMPS ARE CRNTLY (AS OF 330 AM) A60 OVER MOST OF OH. ATTM WE PLAYED IT CLOSE TO THE VEST...WITH EXPECTATION THAT ANY SUNSHINE WILL BE LIMITED. BUT IT IS SOMETHING TO WATCH. MDLS HAVE BEEN LEANING SLOWER WITH THIS DYNAMIC SYSTEM...AND OUR FCST REFLECTS THIS. DO NOT XPCT MUCH PCPN BEFORE 18Z...WITH THE HEAVIEST RAIN LIKELY TO FALL VERY LATE AFTN/EVNG. WE EXPANDED THE FFA TO INCLUDE THE ENTIRE FCST AREA...MAIN THREAT BEING +RA AND FLASH FLOODING...AS MDLS ARE SHIFTING THE HEAVY PCPN AXIS FURTHER TO THE WEST. WE STARTED THE FLOOD WATCH AT 00Z EXPECTING THAT ANY HYDRO ISSUES WILL BE AFTER THIS TIME...BUT DAY SHIFT MAY HAVE TO MOVE UP THE START TIME IF PCPN WORKS IN EARLIER THAN XPCTD. ATTM WE XPCT RAINFALL TO AVG SOMEWHERE BETWEEN 1 AND 2 INCHES....LCLY HIER AMTS IN THE SRLY UPSLOPE FAVORED AREAS...LOWEST AMTS PRBLY IN THE LAKE PLAIN. ADDED TSRA TO THE MIX THIS AFTN/EVNG GIVEN WHAT`S BEEN OCCRRING UPSTREAM AND FCST SI`S FROM 0 TO -2. STRONG DYNAMICS IN ALMOST ANY FLEID YOU LOOK AT...INCLUDING IMPRSV UPR LVL DVRGNC ASSCD WITH THE RR QUAD OF AN UPR LVL JET COUPLED WITH STRONG LOW LVL FNTL CONVERGENCE SO CAT POPS CONTINUE TO LOOK GOOD. STEADIER RAINS WILL END LATER TNGT FROM W TO E...PSBLY MIXING WITH -SHSN TWDS DAYBREAK. POTNL FOR SOME VERY GUSTY WINDS WITH ANY CONVECTION THAT DVLPS NEAR/ALONG THE FNT. GIVEN THIS AND THE STRONG WINDS XPCTD BEHIND THE CDFNT ON THU...WE ISSUED A HIGH WIND WATCH FOR THE ENTIRE RGN. RECORD TEMPS FOR TDA INCLUDE 54F AT SYR (2006/1914), 52 AT BGM (1974), AND 66 AT AVP (1947). SYR AND BGM RECORDS ARE GONERS. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... XPCT STRONG WINDS ON THU. NAM/GFS MOS GDNC SHOWING SUSTAINED 25 TO 30 WHICH IS ONE OF THE BETTER INDICATORS SUGGESTING WARNING CRITERIA WINDS ALONG THE LAKE PLAIN. ISALOBARIC FIELDS ALSO MORE IMPRSV THAN PREV WARNING/ADVISORY EVENT. POTNL FOR WARNING CRITERIA SPCLY ACRS THE LAKE PLAIN AND PSBLY ADJACENT COUNTIES...WITH AN ADVISORY APPEARING LIKELY FOR THE REMAINDER OF THE CWA. AS COLDER AIR WORKS IN ON THU...LES WILL DVLP EAST OF LAKE ONTARIO. PROFILES AND TRAJECTORIES LOOK FVRBL THU AFTN INTO THU NGT FOR SIG ACCUMS AS 850 TEMPS FALL TO -18C...SO AN LES WATCH WAS ISSUED. THIS ACTIVITY IS XPCTD TO DROP SWD LATE THU NGT ON 290-300 FLOW INTO ONON/MAD/SRN ONEIDA. THIS BAND MAY LIFT BACK NWD ON FRI NGT AS LOW LVL FLOW BCMS SWLY AHEAD OF THE NXT CLIPPER. && .LONG TERM /SATURDAY THROUGH TUESDAY/... LK EFFECT SNOW STARTING OFF PD ACRS FAR NRN NY WL TRANSITION NORTH OF THE REGION BY 06Z SATURDAY AS SFC RIDGE NOSES INTO AREA. WK UL TROF WL MV THRU SAT AFTN WITH EC BEING STRONGEST WITH VORT MAX AND GFS WEAKER. THEREFORE HV GONE WITH ONLY CHC POPS AT THIS TIME PER HPC GUIDANCE. POPS WL INCREASE SAT NGT AND SUN AS ANOTHER WV AND ASSOC SFC LOW DROPS THRU THE CWA THO ONLY TO BTWN 40-50%. 12Z GUIDANCE HAS COME INTO BETTER AGREEMENT WITH WV DROPPING INTO NERN U.S. AND DVLPNG SFC LOPRES SUN AFTN/EVNG SOMEWHERE IN THE GULF OF MAINE. ENERGY WL LKLY NOT TRANSFER OFF THE COAST QUICKLY ENUF TO GIVE US A THREAT FOR WIDESPREAD SNOW FOR EARLY NEXT WEEK. TEMPS DRG THE EXTNDD PORTION WL SETTLE OUT CLOSE TO SEASONAL VALUES. && .AVIATION /10Z WEDNESDAY THROUGH SUNDAY/... 06Z WED UPDATE... THE PRIMARY AVIATION IMPACT THE NEXT 12-24 HRS WILL LIKELY BE LLWS...AS A VERY STG LOW-LVL JET DVLPS OVER THE RGN...WITH AN INVERSION ALSO IN PLACE IN THE LWST 2K FT...TO KEEP THE STGST WINDS JUST OFF THE SFC. THIS HAZARD WAS CARRIED AT ALL SITES. THERE IS SOME PSBLTY THAT WARMING SFC TEMPS THIS AFTN WILL BE ENOUGH TO ERODE THE INVERSION...AND BRING STG GUSTY WINDS (35-40 KT) ALL THE WAY TO THE SFC. ALTHOUGH WE FEEL THIS IS A LOW PROB OCCURRENCE...KSYR AND KBGM MAY BE THE MOST PROBABLE SITES FOR THIS (DOWNSLOPING SRLY FLOW AT KSYR AND ADDED ELEVATION AT KBGM). SUCH TRENDS WILL OBVIOUSLY BE WATCHED CLOSELY THROUGHOUT THE DAY. EARLY THIS MRNG...LWR STRATUS CLDS AND FOG ARE EXPECTED TO PREVAIL AT KELM/KBGM/KITH/KAVP...WITH PERSISTENT IFR. KSYR AND KRME SHOULD STAY MVFR TO VFR. FROM ABT 14-21Z...LWR CLDS COULD WELL BREAK FOR A TIME AT KELM/KSYR...WITH MOSTLY VFR. ELSEWHERE...BKN-OVC MVFR CIGS ARE EXPECTED TO PREVAIL. FROM ABT 21Z ONWARD THROUGH THE EVE HRS...AS THE MAIN COLD FRNTL BNDRY SLOWLY APPROACHES...RAIN SHOULD BECOME STEADIER IN NATURE...WITH PREVAILING MVFR CONDS. EMBEDDED CONVECTIVE ELEMENTS ARE CERTAINLY NOT OUT OF THE QUESTION...GIVEN THE STRENGTH OF THIS SYSTEM...AND THE UNSEASONABLE WARMTH IN PLACE. HOWEVER...WE DON`T FEEL CONFIDENT ENOUGH TO INSERT THUNDER OR EXCESSIVE WIND GUSTS (40+ KT) ATTM. ONCE AGN...RADAR TRENDS WILL BE CLOSELY MONITORED THROUGHOUT THE DAY. FOR MOST SITES...FROPA SHOULD OCCUR FM 06-09Z THU (JUST BEYOND THE VALID TAF PD). .OUTLOOK... THU/FRI/SAT/SUN...OCNL MVFR TO IFR RESTRICTIONS...IN SHSN. && .HYDROLOGY... CONSENSUS OF MODEL AND MAN MADE GUID PROGS PUTS UP TO 2 INCHES OF QPF OVER THE WRN CATS AND PARTS OF NEPA. THIS SEEMS RATHER HIGH FOR A FAST MVG COLD FNT BUT WE DO HAVE A WV DVLPG ALONG THE FNT THAT DVLPS GOOD LL CONV THAT IN TURN BRINGS A PD OF SLY OR SELY INFLOW...MAINLY INTO THE CATS. IF WE SEE THE WORST CASE SCENARIO THERE WLD BE SOME MINOR FLOOD PRBLMS ON THE MAIN RVRS. OF BIGGER CNCRN TO ME WLD BE THE SMALLER STREAMS WHERE THIS PTNL RAIN WLD FALL OVER A RELATIVELY SMALL WINDOW...ABT 6 HRS. OTR FACTOR TO ALWAYS CONSIDER IS THE ONGOING PRBLM WITH FLOOD DAMAGED STREAM BEDS IN THE AREA FROM PAST EVENTS. WILL ISSUE A GENERIC FLOOD WATCH FOR THE WESTERN CATS AND MUCH OF NEPA TO CVR THE RAIN AND FLOOD PTNL. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...FLOOD WATCH FROM 4 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR PAZ038>040-043-044-047-048-072. HIGH WIND WATCH FROM THIS EVENING THROUGH THURSDAY EVENING FOR PAZ038>040-043-044-047-048-072. NY...FLOOD WATCH FROM 4 PM EST THIS AFTERNOON THROUGH THURSDAY MORNING FOR NYZ009-015>018-022>025-036-037-044>046- 055>057-062. HIGH WIND WATCH FROM THIS EVENING THROUGH THURSDAY EVENING FOR NYZ009-015>018-022>025-036-037-044>046-055>057-062. LAKE EFFECT SNOW WATCH FROM THURSDAY MORNING THROUGH FRIDAY MORNING FOR NYZ009. && $$ LONG TERM...PVN AVIATION...MLJ/RRM HYDROLOGY...
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
353 AM CST WED JAN 30 2013 .SHORT TERM...TODAY THROUGH FRIDAY NIGHT 353 AM CST WED JAN 30 2013 MAIN FORECAST CONCERNS THIS PACKAGE...WINTER STORM/SNOW AMOUNTS/ WINDS TODAY...TEMPERATURE TRENDS AND INTERMITTENT -SN/FLURRY CHANCES TONIGHT THRU FRI NIGHT. 06Z SURFACE ANALYSIS HAD THE SFC LOW DEEPENING OVER LOWER MI WITH ARCTIC HIGH PRESSURE BUILDING INTO MT. PRESSURE GRADIENT WAS INCREASING ACROSS THE REGION...WITH NORTH TO NORTHWEST WINDS BRINGING IN COLDER AIR AND ERODING THE WARM LAYER ALOFT. -SN IN THE FCST AREA BEING REPORTED AS FAR SOUTHEAST AS KOLZ/KOVS AS OF 0630Z. WV IMAGERY SHOWED A VIGOROUS SHORTWAVE LIFTING THRU THE CENTRAL/SOUTHERN PLAINS AND TOWARD THE REGION. MAIN DEFORMATION BAND OF SNOW WITH THIS FEATURE WAS LIFTING FROM NORTHEAST KS/SOUTHEAST NEB AND MUCH OF THE SOUTHWEST HALF OF IA...MAKING STEADY BUT DELAYED PROGRESS NORTHEAST TOWARD THE AREA. NO GLARING ERRORS NOTED WITH 30.00Z MODEL INITIALIZATIONS. GIVEN THE PASSING STRONG MID LEVEL TROUGH TODAY/TONIGHT AND FLOW TRANSITIONING TO NORTHWEST...SOLUTIONS AS SIMILAR AS CAN BE EXPECTED FOR TODAY THRU FRI NIGHT. DPROG/DT OF 500MB HGTS AT 30.00Z SHOWED THE SLOWER/ STRONGER MODEL RUNS OF 28.00Z AND 29.00Z VERIFIED BEST WITH THE TROUGH OVER THE CENTRAL CONUS. ALL WERE VERY GOOD WITH THE EAST/WEST NOAM COAST RIDGING. ECMWF WITH THE BETTER RUN-TO-RUN CONSISTENCY. MODEL CONSENSUS TRENDS SLOWER AS THE MAIN TROUGH/ENERGY MOVES INTO THE NORTHEAST CONUS BY 12Z THU. TREND CONTINUES A BIT STRONGER WITH A NORTHERN STREAM SHORTWAVE TO DROPS ACROSS MN/WI ON THU. CONSISTENCY GOOD FOR THU NIGHT THRU FRI NIGHT AS NORTHWEST FLOW ALOFT BECOMES ESTABLISHED OVER THE REGION...BUT DIFFERENCES ON DETAILS OF MINOR SHORTWAVES IN THIS FLOW. ECMWF WITH THE BETTER OVERALL RUN-TO-RUN CONSISTENCY TODAY INTO FRI NIGHT. CHECK OF OBS VS. MODEL DATA AT 06Z SHOWED A CONSENSUS LOOKED BEST AS THE SFC LOW DEEPENED OVER LOWER MI. PER WV IMAGERY MODELS ALL LOOK REASONABLE WITH THE SHORTWAVE ENERGY ROTATING AROUND THE EAST SIDE OF THE TROUGH AND TOWARD THE UPPER MIDWEST. ECMWF/NAM LOOKED BEST WITH THE 00-06Z PRECIP ACROSS THE MID/UPPER MS VALLEY. FAVORED A MODEL/ ENSEMBLE CONSENSUS WEIGHTED TOWARD THE ECMWF WITH ITS BETTER RUN-TO- RUN CONSISTENCY AND PERFORMANCE WITH THE 00-06Z MID-CONUS PRECIP. SHORT TERM FCST CONFIDENCE AVERAGE TO GOOD THIS CYCLE. IN THE SHORT TERM...TODAY IS ALREADY PROBLEMATIC DUE TO AN EASTWARD SHIFT OF THE MODEL CONSENSUS WITH QPF /SNOW/ PRODUCTION AND INHERITED HEADLINES. DEFORMATION BAND OF SNOW ASSOCIATED WITH THE STRONG MID LEVEL SHORTWAVE AND MDT/STRONG 850-500MB FN CONVERGENCE STILL TRANSLATES ACROSS THE AREA TODAY. WITH ALL THE MID MS/LOWER OH VALLEY CONVECTION DRIVING THE TROUGH/COLD FRONT EAST...AND INTERCEPTING A LOT OF THE MOISTURE...SHORTWAVE PV ADVECTION/ DIVERGENCE ALOFT AND LOWER/MID LEVEL FN FORCING APPEAR TO HAVE LESS MOISTURE TO WORK WITH THAN EARLIER MODEL RUNS INDICATED. ANOTHER THING WORKING AGAINST HEAVIER QPF/SNOW THRU TODAY IS FASTER MOVEMENT OF THE FORCING ACROSS THE AREA. WHAT LOOKED LIKE IT MIGHT BE 18HRS OF FORCING/LIFT NOW LOOKS MORE LIKE 9-12HRS AS THE SHORTWAVE PASSES. ALL THIS TRENDS TOWARD LESS SNOW FOR THE AREA EARLY THIS MORNING AND TODAY. HAVE ALREADY CANCELED ADVISORIES AND REDUCED WINTER STORM WARNING TO ADVISORY ALONG/NORTHWEST OF A NEW HAMPTON IA-LA CROSSE-BLACK RIVER FALLS LINE. WARNING CONTINUES TO LOOK GOOD ACROSS THE SOUTHEAST 1/3 TO HALF OF THE FCST AREA. MAY NOT QUITE GET 6 INCHES OF SNOW...BUT BLOWING/DRIFTING LATER AS NORTHWEST GRADIENT WINDS CONTINUE TO INCREASE ALONG/SOUTHEAST OF A KOLZ-VIROQUA-NECEDAH WI LINE LOOKING TO MAKE FOR MISERABLE TRAVEL TODAY IN THOSE AREAS. SYSTEM EXITS QUICKLY DURING THE MID/LATE AFTERNOON HOURS AND MAY BE ABLE TO CANCEL SOME HEADLINES EARLY...ESPECIALLY WEST OF THE MS RIVER. ARCTIC AIR POURS INTO THE AREA BEHIND THE DEPARTING LOW TONIGHT. GRADIENT REMAINS TIGHT FOR NORTHWEST WINDS OF 10 TO 20 MPH INTO THU MORNING AS TEMPERATURES HEAD TO NEAR AND BELOW ZERO...PRODUCING WINDS CHILLS OF 20-25 BELOW OVER THE WEST 1/3 OF THE FCST AREA. WILL ISSUE A WIND CHILL ADVISORY ALONG/WEST OF A WABASHA MN TO NEW HAMPTON IA LINE FOR LATE TONIGHT/THU MORNING. THE NORTHERN STREAM SHORTWAVE DROPS ACROSS THE AREA LATE TONIGHT/THU WITH DEEP CYCLONIC CONVERGENCE...RATHER DEEP MOISTURE AND STEEP LOW LEVEL LAPSE RATES ON THU. RAISED -SN CHANCES TO 60 PERCENT ACROSS THE NORTH END OF THE FCST AREA AND 20-50 PERCENT ELSEWHERE ACROSS THE NORTHEAST HALF OF THE FCST AREA FOR TONIGHT/THU...FOR OCCASIONAL VERY LIGHT SNOW THAT MAY SEE SOME 1/2 INCH ACCUMULATIONS OF FLUFF. EVEN COLDER AIRMASS SETTLES OVER THE AREA THU NIGHT WITH 925MB TEMPS IN THE -20C TO -26C RANGE...DEPENDING ON SPECIFIC MODEL DETAILS. WINDS WILL BE LIGHTER...MORE IN THE 5-10MPH RANGE BUT TEMPS AROUND 12Z FRIDAY LOOKING TO BE IN THE -8F TO -16F RANGE. WIND CHILLS THU NIGHT/FRI MORNING HEADED INTO THE -20 TO -35 RANGE AND ANOTHER WIND CHILL ADVISORY WILL BE NEEDED. WILL NOT COMPLICATE HEADLINE PICTURE ANY FURTHER AND LEAVE THIS ONE TO BE ISSUED LATER. DETAILS DIFFER AMONG THE MODELS BY FRI/FRI NIGHT BUT ALL DROP ANOTHER STRONGER SHORTWAVE SOUTHEAST ACROSS THE GREAT LAKES...ALONG WITH A WEAKER ONE SOUTHEAST ACROSS THE NORTHERN PLAINS. THIS SETS OFF A ROUND OF MDT TO STRONG 925-700MB WARM ADVECTION LIFT ACROSS THE REGION. THE QUESTION IS HOW MUCH MOISTURE WILL THERE BE AND WHERE WILL THE STRONGER OF THE ISENTROPIC LIFT/VERTICAL MOTION OCCUR. MODEL CONSENSUS KEEPS THE SFC-850MB LAYER DRY FRI SO WILL LEAVE FRI DRY FOR NOW. SMALL -SN CHANCE FRI NIGHT REASONABLE WITH BETTER INDICATION FOR SFC TO AT LEAST 800MB SATURATION BEING PUSHED INTO THE COLD AIRMASS OVER THE AREA. FAVORING A MODEL/ENSEMBLE CONSENSUS LEAD BY THE ECMWF...USED A BLEND OF THE NUMERICAL TEMPERATURE GUIDANCE WEIGHTED TOWARD THE ECMWF FOR HIGHS/LOWS TODAY THRU FRI NIGHT. TEMPS TO FALL TODAY AS THE ARCTIC AIRMASS SPREADS IN...WITH HIGHS AROUND 12-13Z THIS MORNING. FOR THU NIGHT LOWS...IF WINDS BECOME LIGHT/VARIABLE CALM OVER THE FRESH SNOW COVER IN THE -20C TO -26C 925MB AIRMASS...LOWS IN SOME OF THE SHELTERED VALLEYS/NORMALLY COLDER LOW LAYING AREAS COULD DROP INTO THE -20F TO -30F RANGE. .LONG TERM...SATURDAY THROUGH TUESDAY... 353 AM CST WED JAN 30 2013 NOT A LOT OF TIME SPENT IN THE DAY 4-7 PERIOD AGAIN THIS MORNING WITH ALL THE ISSUES AND HEADLINES IN THE SHORT TERM. 30.00Z MEDIUM RANGE MODELS IN RATHER GOOD AGREEMENT SAT FOR YET ANOTHER STRONGER NORTHWEST FLOW SHORTWAVE TO DROP SOUTHEAST ACROSS THE REGION...THIS ONE ACROSS MN/WI...OVER WHAT WILL STILL BE A RATHER COLD AND EASIER TO SATURATE AIRMASS/COLUMN. SMALL -SN CHANCE SAT LOOKS REASONABLE. GOOD CONSENSUS FOR THE FLOW TO FLATTEN A BIT/BECOME MORE WEST- NORTHWEST SUN INTO MON WITH YET ANOTHER SHORTWAVE TO DROP SOUTHEAST ACROSS THE REGION. MAY YET NEED SMALL -SN CHANCES OVER MUCH OF THE FCST AREA SUN DEPENDING ON DETAILS/WHERE THIS WAVE AND ATTENDANT SFC LOW TRACK. AREA REMAINS UNDER NORTHWEST FLOW ALOFT MON/TUE BUT MODELS DIVERGING WITH TIMING OF UNIDENTIFIABLE SHORTWAVES THRU THE FLOW. FCST CONFIDENCE IN THE LONG TERM LOOKS AVERAGE. GIVEN THIS AND NOT A LOT TIME PICKING THRU THE DETAILS...LITTLE IF ANY CHANGES MADE TO THE THE MODEL/ENSEMBLE CONSENSUS DATA IN THE DAY 4-7 FCST GRIDS. && .AVIATION...THROUGH 06Z THURSDAY 1105 PM CST TUE JAN 29 2013 THE SURFACE LOW HAS MOVED SLOWLY OUT OF NORTHWEST ARKANSAS INTO SOUTH CENTRAL MISSOURI THIS EVENING. THIS HAS RESULTED IN A SLOW NORTHWARD PUSH OF THE SNOW FROM SOUTHWEST IOWA INTO CENTRAL IOWA. THE 30.00Z NAM AND 30.02Z HRRR CONTINUE TO HAVE A GOOD HANDLE ON HOW THE PRECIPITATION HAS BEEN EVOLVING THIS EVENING WITH BOTH MODELS SUGGESTING THAT KLSE HAS A BETTER CHANCE OF GETTING INTO THE PRECIPITATION THAN KRST DOES. WITH THE NORTHEAST MOVEMENT OF THE SNOW...IT IS EXPECTED TO START MOVING INTO KLSE LATE TONIGHT AND KRST AROUND 12Z WITH VISIBILITIES GOING DOWN TO MVFR. AS THE MODERATE TO STRONG FRONTOGENESIS IN THE 750-500 MB LAYER COMES ACROSS WEDNESDAY MORNING...THE SNOW SHOULD INTENSIFY BUT WITH THE BEST ISENTROPIC UP GLIDE ON THE 290K SURFACE REMAINING SOUTHEAST OF BOTH TAF SITES...NOT EXPECTING THE HEAVIEST BAND OF SNOW TO IMPACT EITHER TAF SITE. BOTH SITES SHOULD STILL SEE IFR CONDITIONS BUT THE VISIBILITY SHOULD BE LOWER AT KLSE. KRST WILL SEE IMPROVEMENT STARTING ALREADY LATE WEDNESDAY MORNING AND IN THE EARLY AFTERNOON OR KLSE AS CONDITIONS GO BACK TO MVFR. SOME FLURRIES EXPECTED TO HANG ON DURING THE AFTERNOON WITH VFR VISIBILITY BUT LOOK FOR THE CEILINGS TO REMAIN MVFR FOR THE REMAINDER OF THE PERIOD. THE TIGHT GRADIENT AROUND THE SURFACE LOW WILL PRODUCE SUSTAINED NORTH TO NORTHWEST WINDS OF 15 TO 20 KNOTS WITH GUSTS OF 25 TO 30. THE NAM BUFKIT SOUNDINGS SUGGEST THE LOW LEVEL LAPSE RATES WILL REMAIN STEEP ENOUGH TO KEEP THE GUSTS GOING AFTER SUNSET WEDNESDAY EVENING. && .ARX WATCHES/WARNINGS/ADVISORIES... 353 AM CST WED JAN 30 2013 WI...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR WIZ029- 033-034-041. WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR WIZ042>044-053>055-061. MN...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR MNZ088- 095-096. WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST THURSDAY FOR MNZ079-086-087-094-095. IA...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR IAZ009- 010-018-019. WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST THURSDAY FOR IAZ008-009-018-019. WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR IAZ011- 029-030. && $$ SHORT TERM...RRS LONG TERM....RRS AVIATION.....04
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1005 AM EST WED JAN 30 2013 .SYNOPSIS... A WARM FRONT WILL PUSH NORTH OF THE REGION THIS MORNING...BRINGING MILDER CONDITIONS. WINDS WILL BECOME VERY WINDY LATE THIS AFTERNOON AND TONIGHT AHEAD OF A STRONG COLD FRONT. HEAVY SHOWERS AND ISOLATED THUNDERSTORMS ARE POSSIBLE. THE FRONT WILL PUSH ACROSS THE REGION THURSDAY MORNING...BRINGING WITH MORE WINDY CONDITIONS AND COLDER TEMPERATURES. A COUPLE OF RELATIVELY FAST MOVING SYSTEMS MAY PRODUCE LIGHT SNOW ON SUNDAY AND AGAIN ON TUESDAY OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 1005 AM UPDATE... DENSE FOG CONTINUES TO AFFECT INTERIOR SOUTHERN NEW ENGLAND AS OF MID TO LATE MORNING. BASED ON CURRENT OBSERVATIONS AND TRENDS WILL LIKELY HAVE TO EXTEND IT INTO THE AFTERNOON WITH UNSEASONABLY HIGH DEWPOINT OVER RUNNING TEMPS IN THE LOWER TO MIDDLE 30S. MEANWHILE...ACROSS THE COASTAL PLAIN THE SURFACE HAS MIXED OUT AND TEMPS HAVE SOARED INTO THE 50S. IN FACT...A FEW LOCATIONS MAY TAKE A RUN AT 60 LATER THIS AFTERNOON. NOW WE ARE CONFIDENT THAT TEMPERATURES WILL EVENTUALLY REACH INTO THE 50S ACROSS THE INTERIOR...BUT ITS UNCERTAIN EXACTLY HOW FAST THAT WILL OCCUR. IN SOME LOCATIONS...PARTICULARLY ACROSS SOUTHERN NH THIS MAY NOT HAPPEN UNTIL EARLY EVENING. WE FOLLOWED THE HRRR MODEL TEMPS WHICH SEEM TO HAVE A GOOD HANDLE ON THE SITUATION. MAINLY DRY WEATHER EXPECTED FOR THE NEXT FEW HOURS...BUT SOME SCATTERED SHOWERS MAY WORK INTO THE INTERIOR LATER IN THE AFTERNOON BUT CERTAINLY NOT EXPECTING A WASHOUT. BEST DYNAMICS WILL REMAIN WELL TO OUR WEST FOR THE REMAINDER OF THE AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/... TONIGHT... SHOWERS WILL MOVE IN AHEAD OF APPROACHING FRONT...SOME OF WHICH MAY PRODUCE HEAVY DOWNPOURS. GOOD INSTABILITY CONTINUES AS K INDICES RISE TO THE MID 30S...SO HAVE MENTIONED ISOLD THUNDERSTORMS THROUGH MOST OF THE NIGHT. BIGGEST EFFECTS WILL BE DUE TO STRONG WINDS WITH TIGHT PRES GRADIENT. H85 AND H925 JETS ON ORDER OF 70-80 KT WILL CROSS THE REGION AND...WITH MILD TEMPS REMAINING...EXPECT SOME VERY STRONG GUSTS TO MIX DOWN ESPECIALLY WITH ANY CONVECTION THAT DEVELOPS. LOOKS LIKE THE BIGGEST THREAT FOR THE STRONGEST GUSTS WILL BE ACROSS SOUTHEASTERN SECTIONS. WITH THE THREAT OF DAMAGING WINDS ACROSS RI/SE MA...HAVE ISSUED HIGH WIND WARNING FOR THOSE AREAS. WOULD NOT BE SURPRISED TO SEE GUSTS ON ORDER OF 50-55 MPH...MAYBE EVEN HIGHER. ELSEWHERE...HAVE KEPT THE HIGH WIND WATCH IN PLACE...THOUGH COULD BE CONVERTING TO EITHER A WIND ADVISORY OR WARNING DURING THE DAY SHIFT. EXPECT TEMPS TO ACTUALLY TOP OFF LATE TONIGHT OR EVEN INTO THE WEE HOURS OF THURSDAY. A FEW SPOTS MAY ACTUALLY SEE 60 DEGREES... LIKELY ACROSS EASTERN AREAS. SHORT RANGE MODELS IN GOOD AGREEMENT THAT THE COLD FRONT WILL MOVE INTO WESTERN AREAS AFTER 06Z...REACHING THE E COAST AROUND 12Z OR SO. COLDER AIR WILL START TO SPILL INTO WESTERN AREAS BY AROUND SUNRISE. && .LONG TERM /THURSDAY THROUGH TUESDAY/... HIGHLIGHTS... * WIND ADVISORY STRENGTH WINDS POSSIBLE BEHIND FRONT THU * COLDER THU NIGHT INTO THE WEEKEND * CHANCE OF SNOW...PROBABLY LIGHT...ON SUN AND AGAIN TUE OVERALL PICTURE...STRONG COLD FRONT MOVES OFFSHORE THU. BROAD UPPER LONG WAVE TROF DOMINATES ACROSS EASTERN N AMERICA IN THE LONGER TERM PERIOD WITH SERIES OF QUICK MOVING SHORT WAVE TROFS PASSING THROUGH. SURFACE REFLECTION OF THESE SHORTWAVES ARE CLIPPER SYSTEMS. LOOKS LIKE ONE PASS THRU ON SUN AND ANOTHER TUE. SOME UNCERTAINTY WHETHER THE SURFACE CENTERS WILL PASS JUST N OR JUST S OF SOUTHERN NEW ENGLAND. STEADIER AND SOMEWHAT HIGHER QPF EXPECTED NORTH OF THE CENTER...AND SURFACE LOWS PASSING S OF SOUTHERN NEW ENGLAND CAN ADD A LITTLE MORE QPF DUE TO SOME ATLC INFLOW. AT THIS TIME...NONE OF THESE SYSTEMS LOOK ESPECIALLY POTENT WITH ANY SNOW ACCUM LOOKING TO BE UNDER ADVISORY THRESHOLDS. THIS PICTURE COULD CHANGE AS WE GET CLOSER TO THESE EVENTS. DAY BY DAY PICTURE... THU...DEEP MIXING BEHIND COLD FRONT MAY BE ENOUGH TO SUPPORT WIND ADVISORIES OVER PORTIONS OF THE AREA DURING THE LATE MORNING AND AFTERNOON. NO HEADLINES NOW DUE TO THE PREFRONTAL HIGH WIND WARNINGS/WATCHES. TEMPS MAY HOLD STEADY FOR A WHILE DURING THE MORNING AND START A STEADY SLIDE DURING THE AFTERNOON INTO THU NIGHT DUE TO STRONG COLD AIR ADVECTION. FRI...ALL MODELS INDICATE A FAIRLY WELL DEFINED SHORT WAVE TROF PASSAGE ON FRI. MOISTURE IS LIMITED BUT SHARPNESS OF THE TROF SUGGESTS MENTION OF SCT FLURRIES. SAT...LOOKS DRY WITH BELOW NORMAL TEMPS. SUN...SHORT WAVE TROF WITH BAGGINESS IN SFC PRES FIELD DEPICTED BY MEDIUM RANGE MODELS SUGGESTS A CHANCE OF LIGHT SNOW. ALTHOUGH THE GFS SHOWS A TAD MORE QPF...THE ECMWF ACTUALLY SHOWS A SOMEWHAT SHARPER SHORT WAVE TROF WITH A NEGATIVE TILT HINT. PUT POPS AT 50 PERCENT FOR MOST OF AREA FOR SUN. MON-TUE...MON LOOKS DRY BEFORE ANOTHER SHORT WAVE UPPER TROF AND SFC CLIPPER LOW PASSES THRU WITH ANOTHER CHANCE OF A PERIOD OF LIGHT SNOW. GFS ENSEMBLES SEEM TO FAVOR A SLIGHTLY MORE SOUTHERLY TRACK WITH THIS LOW CENTER COMPARED WITH THE ONE ON SUN BUT TOO FAR OUT FOR MUCH CONFIDENCE. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW...MODERATE TO HIGH CONFIDENCE ON TRENDS BUT LOW CONFIDENCE ON TIMING. REST OF TODAY...IFR TO LOW END MVFR CONDITIONS WILL PERSIST ON THE COASTAL PLAIN. MAINLY LIFR CONDITIONS WILL CONTINUE AT LEAST INTO MID AFTERNOON ACROSS THE INTERIOR AS A RESULT OF DENSE FOG. CONDITIONS SHOULD EVENTUALLY IMPROVE TO IFR...BUT THAT MAY NOT OCCUR UNTIL LATER THIS AFTERNOON/EARLY EVENING. LOW LEVEL JET MOVES IN WITH S-SW WINDS UP TO 50-60 KT DURING THIS AFTERNOON. EXPECT GUSTS UP TO 30-40 KT AT THE SURFACE MAINLY ACROSS RI/SE MA AND HIGHER TERRAIN. TONIGHT...MVFR VSBYS/IFR-LIFR CIGS PREVALENT AS STRONG COLD FRONT MOVES THROUGH. LLWS CONTINUES...APPROACHING 75 KT AT 2KFT ALONG THE S COAST...CAPE COD AND THE ISLANDS...POSSIBLY APPROACHING 80 KT ACROSS OUTER CAPE COD AND NANTUCKET AFTER 09Z THU. EXPECT SURFACE GUSTS OF 40-50 KT ACROSS MOST AREAS...POSSIBLY UP TO 55 KT ALONG S COAST. ISOLD TSTMS POSSIBLE ALONG/AHEAD OF COLD FRONT. CIGS/VSBYS MAY START TO IMPROVE TO VFR ACROSS CT VALLEY AFTER 09Z...THOUGH LOWER CONFIDENCE ON TIMING. KBOS TAF...MODERATE CONFIDENCE. IFR TO LOW END MVFR CONTINUES THROUGH THE AFTERNOON. SW LLWS EXPECTED THIS AFTERNOON/TONIGHT. SW SURFACE WIND GUSTS UP TO 40-50 KT FROM 03Z-11Z. KBDL TAF...MODERATE CONFIDENCE. LIFR CONDITIONS IN DENSE FOG SHOULD EVENTUALLY IMPROVE TO IFR SOMETIME THIS AFTERNOON. S-SW LLWS EXPECTED THROUGH TONIGHT. S-SW WIND GUSTS UP TO 40-50 KT FROM 04Z-10Z. OUTLOOK...THURSDAY THROUGH SUNDAY... HIGH CONFIDENCE OF VFR CONDITIONS BY LATE MORNING THU AND LASTING THRU SAT. LOW TO MODERATE CONFIDENCE OF MVFR CIGS/VSBYS WITH POCKETS OF IFR IN SNOW SUN. SFC WIND GUSTS 35 TO 45 KT LIKELY BEHIND COLD FRONT THU AFTERNOON AND CONTINUING TO GUST TO AROUND 25 KT THU NIGHT AND FRI. && .MARINE... MODERATE TO HIGH CONFIDENCE THROUGH TONIGHT. TODAY...S-SW WINDS WILL PICK UP DURING THE DAY...POSSIBLY REACHING GALE FORCE ON THE OPEN WATERS THIS AFTERNOON. SEAS WILL ALSO BUILD...UP TO 8 FT ON THE SOUTHERN WATERS BY EVENING. TONIGHT...EXPECT STRONGEST S-SW WINDS TO MOVE ACROSS THE WATERS DURING THIS TIMEFRAME. MAY SEE WIND GUSTS UP TO 50-55 KT OVER THE OPEN WATERS SO HAVE ISSUED STORM WARNINGS. WINDS MAY NOT QUITE REACH STORM FORCE ON BOSTON HARBOR OR NARRAGANSETT BAY...SO ISSUED GALES FOR THOSE WATERS. SEAS MAY REACH 15-18 FT ON THE SOUTHERN OUTER WATERS LATE TONIGHT. OUTLOOK...THURSDAY THROUGH SUNDAY... MODERATE TO HIGH CONFIDENCE THRU SATURDAY. MODERATE CONFIDENCE FOR SUNDAY. STORM FORCE WINDS AHEAD OF FRONT AND THEN STRONG GALE LIKELY BEHIND THE FRONT FROM W TO NW WITH GUSTS 40 TO 45 KT THU AFTERNOON AND EVENING. WINDS GRADUALLY DIMINISHING LATE THU NIGHT INTO FRI BUT MAY STILL SEE GUSTS BETWEEN 25 AND 30 KT ON FRI. WINDS SHOULD BE UNDER SMALL CRAFT ADVISORY THRESHOLDS ON SAT BUT POSSIBLY REACHING TO NEAR GALE FORCE IN GUSTS OVER OUTER S AND SE COASTAL WATERS SUN AFTERNOON FROM W OR WNW AS DEPARTING LOW OVER THE GULF OF MAINE INTENSIFIES. AREAS OF FREEZING SPRAY POSSIBLE LATE THU NIGHT THRU SAT. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...DENSE FOG ADVISORY UNTIL NOON EST TODAY FOR CTZ002>004. HIGH WIND WATCH FROM 6 PM EST THIS EVENING THROUGH THURSDAY MORNING FOR CTZ002>004. MA...DENSE FOG ADVISORY UNTIL NOON EST TODAY FOR MAZ002>005-008>012- 026. HIGH WIND WATCH FROM 6 PM EST THIS EVENING THROUGH THURSDAY MORNING FOR MAZ002>016-026. HIGH WIND WARNING FROM 9 PM THIS EVENING TO 8 AM EST THURSDAY FOR MAZ017>024. NH...DENSE FOG ADVISORY UNTIL NOON EST TODAY FOR NHZ011-012-015. HIGH WIND WATCH FROM 6 PM EST THIS EVENING THROUGH THURSDAY MORNING FOR NHZ011-012-015. RI...DENSE FOG ADVISORY UNTIL NOON EST TODAY FOR RIZ001. HIGH WIND WARNING FROM 9 PM THIS EVENING TO 8 AM EST THURSDAY FOR RIZ001>008. MARINE...STORM WARNING FROM 6 PM THIS EVENING TO 11 AM EST THURSDAY FOR ANZ231>235-237-250-251-254>256. GALE WARNING FROM 6 PM THIS EVENING TO 11 AM EST THURSDAY FOR ANZ230-236. && $$ SYNOPSIS...EVT/THOMPSON NEAR TERM...FRANK SHORT TERM...EVT LONG TERM...THOMPSON AVIATION...FRANK/EVT/THOMPSON MARINE...EVT/THOMPSON
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
1132 AM EST WED JAN 30 2013 ...WINDY WITH RECORD WARMTH THIS AFTERNOON... ...SLIGHT RISK OF SEVERE THUNDERSTORMS WITH DAMAGING WIND GUSTS IN SOUTHEAST GEORGIA THIS EVENING... .CURRENTLY... MORNING SURFACE ANALYSIS DEPICTS A STRONG COLD FRONT EXTENDING FROM THE OHIO VALLEY SOUTHWARD TO THE CENTRAL GULF COAST AND THE WESTERN GULF OF MEXICO. WAVES OF LOW PRESSURE ARE PROGRESSING NORTHEASTWARD ALONG THIS FRONT...AND AN EXTENSIVE SQUALL LINE IS FOUND JUST AHEAD OF THE FRONT. THIS SQUALL LINE IS ENTERING NORTHWEST GEORGIA AND TRAILS SOUTH-SOUTHWESTWARD THROUGH ALABAMA AND SOUTHERN MISSISSIPPI. THIS SQUALL LINE HAS PRODUCED NUMEROUS REPORTS OF DAMAGING WINDS AND ISOLATED TORNADOES DURING THE PAST 24 HOURS. ALOFT...DEEP-LAYERED RIDGING WAS SITUATED OVER THE WESTERN ATLANTIC...WHILE A SHARP TROUGH OVER THE MISSOURI VALLEY WAS IN THE PROCESS OF BECOMING NEGATIVELY TILTED. THIS WEATHER PATTERN HAS BROUGHT A STRONG VEERING WIND PROFILE INTO OUR REGION. THE MORNING SOUNDING AT JACKSONVILLE REVEALED 35 KNOT WINDS AT 1000 FEET. SUSTAINED SOUTHERLY SURFACE WIND SPEEDS ARE ALREADY EXCEEDING 20 KNOTS IN SOME LOCATIONS...AND WE MAY NEED TO EXTEND THE WIND ADVISORY TO COVER ALL OF OUR COUNTIES THIS AFTERNOON AS THE GRADIENT TIGHTENS FURTHER. NEAR ALL-TIME JANUARY RECORDS ARE POSSIBLE THIS AFTERNOON AT JACKSONVILLE (84 DEGREES...LAST REACHED IN 1982) AND ALMA (83 DEGREES...REACHED YESTERDAY). THE STORM PREDICTION CENTER HAS MAINTAINED A SLIGHT RISK FOR SEVERE THUNDERSTORMS DUE TO DAMAGING WIND GUSTS FOR OUR SOUTHEAST GA COUNTIES. LATEST RUC GUIDANCE SUGGESTS THAT A FEW SHOWERS WILL DEVELOP OVER THE NORTHEAST GULF THIS AFTERNOON...WHICH WILL MOVE QUICKLY INTO INTERIOR SE GA. SLOWED THE SOUTHEASTWARD PROGRESSION OF POPS LATE THIS AFTERNOON/EVENING DUE TO LATEST TRENDS IN THE SHORT TERM GUIDANCE. MODEL SOUNDINGS SUGGEST A UNI-DIRECTIONAL SHEAR VECTOR BY THE TIME THE SQUALL LINE ARRIVES IN SE GA AND THE FL BIG BEND AROUND SUNSET. INSTABILITY WILL ALMOST NEGLIGIBLE PER MODEL SOUNDINGS...AND THUS NOT EXPECTING A WIDESPREAD SEVERE WEATHER EVENT...AS DYNAMICS WILL ALSO BE LIFTING NORTHWARD AND AWAY FROM OUR REGION AS THE SQUALL LINE MOVES THROUGH. RAINFALL AMOUNTS OF ONE QUARTER TO ONE HALF INCH ARE EXPECTED WITH THIS EVENT. RAIN SHOULD END OVER OUR SOUTHERN COUNTIES BY 09Z. && .AVIATION... VFR CONDITIONS WILL PREVAIL THROUGH AT LEAST 02Z. SOUTHERLY SURFACE WINDS WILL REMAIN SUSTAINED AT 15 TO 25 KTS AT ALL TAF SITES THROUGH 00Z. SURFACE GUSTS UP TO 35 KNOTS ARE EXPECTED AFTER 16Z. SURFACE WINDS WILL BECOME SOUTHWESTERLY TOWARDS 00Z AND THEN WESTERLY AFTER 06Z FOLLOWING THE PASSAGE OF A COLD FRONT. SHOWERS AND ISOLATED EMBEDDED THUNDERSTORMS WILL PROGRESS ACROSS THE TERMINALS FROM 02Z-06Z...WITH A PERIOD OF SUB-VFR CONDITIONS LIKELY DURING THIS TIME PERIOD. A FEW LINGERING SHOWERS ARE POSSIBLE THROUGH 09Z. SOUTH TO SOUTHWEST WINDS OF 25 TO 35 KTS FROM 2000 TO 10000 FEET WILL INCREASE TO 40 TO 55 KTS TOWARDS 00Z. && .MARINE... SMALL CRAFT ADVISORIES ARE POSTED THROUGH THURSDAY...WITH SOUTH WINDS INCREASING TO 20 TO 30 KNOTS WITH OCCASIONAL GUSTS TO GALE FORCE. MORE GALE FORCE GUSTS POSSIBLE TONIGHT AS SQUALL LINE MOVES OFFSHORE...THEN SHIFT TO W/NW LATE TONIGHT WITH STRONG COLD AIR PUSH BEHIND THE FRONT THURSDAY MORNING WITH A SUBSIDING TREND FOR THU AFTERNOON. EXPECTING GALE FORCE GUSTS TO BE PREVALENT FOR A SHORT TIME DURING THE PASSAGE OF THE SQUALL LINE...SO WE WILL NOT ISSUE A GALE WARNING AT THIS TIME. HIGH PRESSURE WILL THEN BUILD IN THROUGH THE WEEKEND...WITH HEADLINES NOT ANTICIPATED AT THIS TIME. RIP CURRENTS: LOW RISK WITH SIDE-SHORE FLOW TODAY AND OFFSHORE FLOW ON THURSDAY. .FIRE WX... STRONG SOUTH WINDS TODAY WILL PUSH DISPERSION INDICES WELL ABOVE CRITICAL LEVELS CLOSE TO 100...BUT RH LEVELS WILL REMAIN GENERALLY ABOVE 40 PERCENT. FOR THURS...COOL AND DRY AIRMASS WILL PUSH IN ON NORTHWEST WINDS AND EXPECT CRITICAL RH VALUES DOWN AROUND 25 PERCENT...BUT SUSTAINED WINDS MAY REMAIN JUST BELOW 15 MPH. ERC VALUES MAY ALSO DECREASE DEPENDING UPON AMOUNT OF RAINFALL TONIGHT. WILL CONSIDER A FIRE WEATHER WATCH DURING THE AFTERNOON FORECAST PACKAGE GIVEN THESE FACTORS. && .PRELIMINARY POINT TEMPS/POPS... AMG 81 45 59 33 / 50 60 10 0 SSI 79 48 59 39 / 20 60 10 0 JAX 84 48 61 33 / 20 70 10 0 SGJ 82 53 61 39 / 20 60 10 0 GNV 82 51 62 33 / 20 70 10 0 OCF 84 53 63 34 / 20 60 10 0 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR ALACHUA-BAKER- BRADFORD-COLUMBIA-GILCHRIST-HAMILTON-SUWANNEE-UNION. LAKE WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR CLAY-DUVAL- FLAGLER-MARION-NASSAU-PUTNAM-ST JOHNS. GA...WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR APPLING-ATKINSON- BACON-BRANTLEY-CHARLTON-CLINCH-COFFEE-ECHOLS-JEFF DAVIS- PIERCE-WARE-WAYNE. LAKE WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR COASTAL CAMDEN-COASTAL GLYNN-INLAND CAMDEN-INLAND GLYNN. AM...SMALL CRAFT ADVISORY UNTIL 3 PM EST THURSDAY FOR ALTAMAHA SOUND GA TO FERNANDINA BEACH FL 20 NM TO 60 NM OFFSHORE- FERNANDINA BEACH TO ST AUGUSTINE FL 20 NM TO 60 NM OFFSHORE- ST AUGUSTINE TO FLAGLER BEACH FL 20 NM TO 60 NM OFFSHORE. SMALL CRAFT ADVISORY FOR WINDS UNTIL 11 AM EST THURSDAY FOR ALTAMAHA SOUND GA TO FERNANDINA BEACH FL OUT 20 NM- FERNANDINA BEACH TO ST AUGUSTINE FL OUT 20 NM-ST AUGUSTINE TO FLAGLER BEACH FL OUT 20 NM. && $$ NELSON/ENYEDI/CHASE
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
108 PM EST WED JAN 30 2013 .PREV DISCUSSION... /ISSUED 1043 AM EST WED JAN 30 2013/ UPDATE... HAVE MADE UPDATES TO THE WEATHER AND POP GRIDS...AND SLOWED DOWN THE CURRENT TIMING OF THE SQUALL LINE. WE ARE STARTING TO SEE ISOLATED SUPERCELLS OUT FRONT OF THE MAIN LINE. THERE IS AN ESPECIALLY STRONG TO SEVERE CELL IN EAST CENTRAL ALABAMA. WE ARE STILL ON TRACK FOR SEVERE THUNDERSTORMS TODAY THROUGH THE AREA. THE MAIN LINE IS EXPECTED TO PUSH THROUGH THE STATE WITH STRONG WINDS BEING THE MAIN THREAT. THERE IS ALSO A RISK OF TORNADOES WITH THESE STORMS...ESPECIALLY ANY SUPERCELLS OUT IN FRONT OF THE LINE. DID ADJUST THE TEMPERATURES DOWN A FEW DEGREES AS THEY WERE FORECAST WARMER THAN WHAT WAS GOING ON. NO OTHER UPDATES ARE EXPECTED AT THIS TIME. ARG PREV DISCUSSION... /ISSUED 647 AM EST WED JAN 30 2013/ PREV DISCUSSION... /ISSUED 621 AM EST WED JAN 30 2013/ UPDATE... SECOND UPDATE TO INCLUDE EXPANDED TORNADO WATCH 17 AREA IN THE FFC WATCHES/WARNINGS/ADVISORIES SECTION BELOW. BELANGER PREV DISCUSSION... /ISSUED 410 AM EST WED JAN 30 2013/ SHORT TERM /TODAY THROUGH THURSDAY NIGHT/... PRIMARY CONCERN IS THREAT AND TIMING OF SEVERE CONVECTION THIS AFTERNOON AND EARLY EVENING. VERY IMPRESSIVE STORM SYSTEM APPROACHING THE STATE THIS MORNING. WHILE FAVORABLE SIG TOR PARAMETER VALUES CURRENTLY CONFINED TO AREA CLOSER TO THE COAST BASED ON RAP ANALYSES...HAVE SEEN A FEW REPORTS OF WIND DAMAGE FURTHER NORTH OVER WRN TN AND NRN MS IN LOW CAPE AREAS. IF MODELS ARE TO BE BELIEVED...PARAMETERS SHOULD BE MORE FAVORABLE HERE THAN WHAT IS CURRENTLY SHOWN TO THE WEST. 00Z MODELS HAVE SLOWED TIMING OF MAIN LINE OF TSRA SOMEWHAT WITH NAM SLOWEST. 06Z NAM ALSO CONTINUING SLOWER TREND. LINE SHOULD MOVE INTO NW CORNER OF CWA AROUND 10AM... I-85 BY 3PM AND AHN-MCN-AMERICUS LINE BY 7PM AND EXITING SE CORNER OF CWA AROUND 10PM. INGREDIENTS STILL APPEAR SUFFICIENT FOR AT LEAST ISOLD AREAS OF WIND DMG OR BRIEF TORNADOES. AS OFTEN THE CASE...06Z NAM MLCAPE SHOWING MORE INSTABILITY THAN OTHER MODELS WITH VALUES AROUND 400-700 J/KG. 00Z GFS HAS 200-400 J/KG OVER ALL BUT NE GA. VERTICAL WIND SHEAR WILL BE VERY STRONG. 0-1KM BULK SHEAR 40-50KTS SEEN ON GFS AND NAM. FAVORABLE CIN...LCL AND DEEP LAYER SHEAR YIELDING DECENT SIG TOR PARAMETER VALUES... 1-2 WITH GFS AND 2-5 ON NAM. THIS VALUES ARE HIGHER THAN PREV SVR EVENT ON DEC 26 WHEN WE SAW 3 WEAK TORNADOES IN MIDDLE GA. WINDS STILL SHOULD KEEP MOST OF AREA IN ADV CRITERIA TODAY AND THIS EVENING. HAVE EXTENDED WIND ADV TIL MIDNIGHT. HIGH WIND WARNING CRITERIA NOT QUITE BEING MET IN LATEST MODEL GRIDS...BUT VERY CLOSE. WITH WET SOILS DEVELOPING QUICKLY THIS AFTERNOON...HAVE CONTINUED WIND WARNING THRU 6PM...AFTER WHICH TIME LLJ WILL SHIFT EAST OF THE NE GA MOUNTAINS. HEAVY RAIN WILL ALSO BE SIGNIFICANT THREAT. AGREE WITH LATEST HPC GUIDANCE WHICH HAS BUMPED UP EVENT TOTAL PRECIP TO 1 TO 2 INCHES WITH SOME AREAS OF NE GA APPROACHING 2.5 INCHES...DUE TO SLOWER TIMING AND PROGRESSION OF TSRA. SFC DEWPOINTS HAVE BEEN HIGHER THAN FCST LAST SEVERAL HOURS AS WELL. BASED ON LATEST GRIDDED FFG AND QPF...HAVE EXPANDED FLOOD WATCH SOUTH TO AREAS NORTH OF A FRANKLIN TO ROSWELL TO CLEVELAND LINE. FINALLY...ANOTHER LOW AMPLITUDE SHORT WAVE PROGGED TO MOVE ALONG LONG WAVE TROUGH OVER TN VALLEY THURS NIGHT. WITH COLD AIR IN PLACE...ESP ALOFT...COULD SEE SOME FLURRIES OR VERY LIGHT SNOW SHOWERS. NO IMPACTS EXPECTED. SNELSON LONG TERM /FRIDAY THROUGH TUESDAY/... EXTENDED MODELS IN FAIRLY GOOD AGREEMENT THROUGH THE LONG TERM...WITH LONG WAVE UPPER-LEVEL TROUGH SITUATED OVER THE EASTERN U.S. THOUGH EARLY NEXT WEEK. GENERALLY...NORTHWEST FLOW WILL PERSIST OVER THE REGION...AND MODELS CONTINUE TO ADVERTISE A SERIES OF UPPER LEVEL SHORT WAVES IMPACTING THE AREA AS A RESULT. THE FIRST DISTURBANCE OCCURS AT THE TAIL END OF THE SHORT TERM PERIODS...AND WHAT MOISTURE QUICKLY DISSIPATES INTO THE LONG TERM EARLY FRIDAY. THE SECOND DISTURBANCE LOOKS TO APPROACH THE AREA LATE SATURDAY AND REMAIN ACROSS FAR NORTH GEORGIA EARLY SUNDAY...WITH SLIGHTLY MORE MOISTURE AVAILABLE THAN THE PREVIOUS SHORTWAVE. FOR NOW...WITH THE LATEST MODEL TIMING FOR THIS SYSTEM...LOOKS LIKE IT WILL PRIMARILY BE RAIN...WITH SOME POSSIBILITY OF A RAIN-SNOW MIX INTO SUNDAY MORNING. HAVE GENERALLY GONE WITH SLIGHT CHANCE POPS...AND HAVE KEPT NO ACCUMULATIONS FOR NORTH GEORGIA. HAVE SCALED BACK POPS SLIGHTLY FOR THE THIRD SHORT WAVE EXPECTED MONDAY NIGHT INTO TUESDAY. LATEST MODEL RUNS ARE LESS ENTHUSIASTIC WITH THE FRONTAL SUPPORT...AND THEREFORE LESS AGGRESSIVE WITH MOISTURE AND PRECIP POTENTIAL. HAVE CONTINUED WITH SLIGHT CHANCE POPS MONDAY NIGHT AND TUESDAY...AND QUICKLY DROP POPS OFF INTO TUESDAY NIGHT. BELANGER FIRE WEATHER... AS DRY AIR PLUNGES IN BEHIND FRONT...HUMIDITY PROGGED TO DROP TO 22 TO 25 PCT FOR A FEW HOURS THURS AFTERNOON OVER MIDDLE GA. WITH 1 TO 2 INCHES OF RAIN EXPECTED TODAY...FUELS ARE EXPECTED TO BE TOO WET TO REQUIRE ANY FIRE DANGER STATEMENTS. SNELSON .AVIATION... 18Z UPDATE... MVFR CONDITIONS EXPECTED THROUGH THE DAY TODAY AND THROUGH EARLY EVENING ACROSS MOST OF THE AREA. AFTER THE MOISTURE CLEARS OUT...EXPECT VFR CONDITIONS. MAIN CONCERN TODAY IS THE TIMING OF THE SQUALL LINE MOVING THROUGH THE AREA. HAVE ADJUSTED THE TAFS FOR BEST TIMING...POTENTIAL EXISTS FOR SEVERE WEATHER WITH THESE STORMS INCLUDING DAMAGING WIND AND POSSIBLE TORNADOES. //ATL CONFIDENCE...18Z UPDATE... MEDIUM CONFIDENCE ON TIMING...HIGH CONFIDENCE ON ALL OTHER ELEMENTS. ARG && .PRELIMINARY POINT TEMPS/POPS... ATHENS 71 38 50 33 / 100 100 5 5 ATLANTA 67 35 49 33 / 100 60 5 5 BLAIRSVILLE 61 32 43 27 / 100 60 5 20 CARTERSVILLE 67 34 47 31 / 100 40 5 10 COLUMBUS 72 38 56 39 / 100 70 5 5 GAINESVILLE 63 35 47 32 / 100 70 5 10 MACON 73 39 55 33 / 90 100 5 5 ROME 68 33 48 31 / 100 40 5 10 PEACHTREE CITY 68 36 51 32 / 100 60 5 5 VIDALIA 80 46 59 36 / 70 90 0 5 && .FFC WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR THE FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BARTOW...BIBB...BLECKLEY... BUTTS...CARROLL...CATOOSA...CHATTAHOOCHEE...CHATTOOGA... CHEROKEE...CLARKE...CLAYTON...COBB...COWETA...CRAWFORD...CRISP... DADE...DEKALB...DODGE...DOOLY...DOUGLAS...EMANUEL...FAYETTE... FLOYD...FORSYTH...GLASCOCK...GORDON...GREENE...GWINNETT...HALL... HANCOCK...HARALSON...HARRIS...HEARD...HENRY...HOUSTON... JACKSON...JASPER...JEFFERSON...JOHNSON...JONES...LAMAR... LAURENS...MACON...MADISON...MARION...MERIWETHER...MONROE... MONTGOMERY...MORGAN...MUSCOGEE...NEWTON...NORTH FULTON... OCONEE...OGLETHORPE...PAULDING...PEACH...PIKE...POLK...PULASKI... PUTNAM...ROCKDALE...SCHLEY...SOUTH FULTON...SPALDING...STEWART... SUMTER...TALBOT...TALIAFERRO...TAYLOR...TELFAIR...TOOMBS... TREUTLEN...TROUP...TWIGGS...UPSON...WALKER...WALTON...WARREN... WASHINGTON...WEBSTER...WHEELER...WHITFIELD...WILCOX...WILKES... WILKINSON. TORNADO WATCH UNTIL 4 PM EST THIS AFTERNOON FOR THE FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BARTOW...BIBB...BLECKLEY... BUTTS...CARROLL...CATOOSA...CHATTAHOOCHEE...CHATTOOGA... CHEROKEE...CLARKE...CLAYTON...COBB...COWETA...CRAWFORD...DADE... DAWSON...DEKALB...DOOLY...DOUGLAS...FANNIN...FAYETTE...FLOYD... FORSYTH...GILMER...GORDON...GREENE...GWINNETT...HALL...HANCOCK... HARALSON...HARRIS...HEARD...HENRY...HOUSTON...JACKSON...JASPER... JONES...LAMAR...LUMPKIN...MACON...MADISON...MARION... MERIWETHER...MONROE...MORGAN...MURRAY...MUSCOGEE...NEWTON... NORTH FULTON...OCONEE...OGLETHORPE...PAULDING...PEACH... PICKENS...PIKE...POLK...PULASKI...PUTNAM...ROCKDALE...SCHLEY... SOUTH FULTON...SPALDING...STEWART...SUMTER...TALBOT... TALIAFERRO...TAYLOR...TOWNS...TROUP...TWIGGS...UNION...UPSON... WALKER...WALTON...WEBSTER...WHITE...WHITFIELD...WILKES... WILKINSON. HIGH WIND WARNING UNTIL 6 PM EST THIS EVENING FOR THE FOLLOWING ZONES: DAWSON...FANNIN...GILMER...LUMPKIN...MURRAY...PICKENS... TOWNS...UNION...WHITE. FLOOD WATCH UNTIL MIDNIGHT EST TONIGHT FOR THE FOLLOWING ZONES: BARTOW...CATOOSA...CHATTOOGA...CHEROKEE...COBB...DADE...DAWSON... FANNIN...FLOYD...FORSYTH...GILMER...GORDON...HARALSON... LUMPKIN...MURRAY...NORTH FULTON...PAULDING...PICKENS...POLK... TOWNS...UNION...WALKER...WHITE...WHITFIELD. WIND ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT EST TONIGHT FOR THE FOLLOWING ZONES: DAWSON...FANNIN...GILMER...LUMPKIN... MURRAY...PICKENS...TOWNS...UNION...WHITE. && $$ SHORT TERM...ARG LONG TERM....11 AVIATION...ARG
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
1043 AM EST WED JAN 30 2013 .UPDATE... HAVE MADE UPDATES TO THE WEATHER AND POP GRIDS...AND SLOWED DOWN THE CURRENT TIMING OF THE SQUALL LINE. WE ARE STARTING TO SEE ISOLATED SUPERCELLS OUT FRONT OF THE MAIN LINE. THERE IS AN ESPECIALLY STRONG TO SEVERE CELL IN EAST CENTRAL ALABAMA. WE ARE STILL ON TRACK FOR SEVERE THUNDERSTORMS TODAY THROUGH THE AREA. THE MAIN LINE IS EXPECTED TO PUSH THROUGH THE STATE WITH STRONG WINDS BEING THE MAIN THREAT. THERE IS ALSO A RISK OF TORNADOES WITH THESE STORMS...ESPECIALLY ANY SUPERCELLS OUT IN FRONT OF THE LINE. DID ADJUST THE TEMPERATURES DOWN A FEW DEGREES AS THEY WERE FORECAST WARMER THAN WHAT WAS GOING ON. NO OTHER UPDATES ARE EXPECTED AT THIS TIME. ARG && .PREV DISCUSSION... /ISSUED 647 AM EST WED JAN 30 2013/ PREV DISCUSSION... /ISSUED 621 AM EST WED JAN 30 2013/ UPDATE... SECOND UPDATE TO INCLUDE EXPANDED TORNADO WATCH 17 AREA IN THE FFC WATCHES/WARNINGS/ADVISORIES SECTION BELOW. BELANGER PREV DISCUSSION... /ISSUED 410 AM EST WED JAN 30 2013/ SHORT TERM /TODAY THROUGH THURSDAY NIGHT/... PRIMARY CONCERN IS THREAT AND TIMING OF SEVERE CONVECTION THIS AFTERNOON AND EARLY EVENING. VERY IMPRESSIVE STORM SYSTEM APPROACHING THE STATE THIS MORNING. WHILE FAVORABLE SIG TOR PARAMETER VALUES CURRENTLY CONFINED TO AREA CLOSER TO THE COAST BASED ON RAP ANALYSES...HAVE SEEN A FEW REPORTS OF WIND DAMAGE FURTHER NORTH OVER WRN TN AND NRN MS IN LOW CAPE AREAS. IF MODELS ARE TO BE BELIEVED...PARAMETERS SHOULD BE MORE FAVORABLE HERE THAN WHAT IS CURRENTLY SHOWN TO THE WEST. 00Z MODELS HAVE SLOWED TIMING OF MAIN LINE OF TSRA SOMEWHAT WITH NAM SLOWEST. 06Z NAM ALSO CONTINUING SLOWER TREND. LINE SHOULD MOVE INTO NW CORNER OF CWA AROUND 10AM... I-85 BY 3PM AND AHN-MCN-AMERICUS LINE BY 7PM AND EXITING SE CORNER OF CWA AROUND 10PM. INGREDIENTS STILL APPEAR SUFFICIENT FOR AT LEAST ISOLD AREAS OF WIND DMG OR BRIEF TORNADOES. AS OFTEN THE CASE...06Z NAM MLCAPE SHOWING MORE INSTABILITY THAN OTHER MODELS WITH VALUES AROUND 400-700 J/KG. 00Z GFS HAS 200-400 J/KG OVER ALL BUT NE GA. VERTICAL WIND SHEAR WILL BE VERY STRONG. 0-1KM BULK SHEAR 40-50KTS SEEN ON GFS AND NAM. FAVORABLE CIN...LCL AND DEEP LAYER SHEAR YIELDING DECENT SIG TOR PARAMETER VALUES... 1-2 WITH GFS AND 2-5 ON NAM. THIS VALUES ARE HIGHER THAN PREV SVR EVENT ON DEC 26 WHEN WE SAW 3 WEAK TORNADOES IN MIDDLE GA. WINDS STILL SHOULD KEEP MOST OF AREA IN ADV CRITERIA TODAY AND THIS EVENING. HAVE EXTENDED WIND ADV TIL MIDNIGHT. HIGH WIND WARNING CRITERIA NOT QUITE BEING MET IN LATEST MODEL GRIDS...BUT VERY CLOSE. WITH WET SOILS DEVELOPING QUICKLY THIS AFTERNOON...HAVE CONTINUED WIND WARNING THRU 6PM...AFTER WHICH TIME LLJ WILL SHIFT EAST OF THE NE GA MOUNTAINS. HEAVY RAIN WILL ALSO BE SIGNIFICANT THREAT. AGREE WITH LATEST HPC GUIDANCE WHICH HAS BUMPED UP EVENT TOTAL PRECIP TO 1 TO 2 INCHES WITH SOME AREAS OF NE GA APPROACHING 2.5 INCHES...DUE TO SLOWER TIMING AND PROGRESSION OF TSRA. SFC DEWPOINTS HAVE BEEN HIGHER THAN FCST LAST SEVERAL HOURS AS WELL. BASED ON LATEST GRIDDED FFG AND QPF...HAVE EXPANDED FLOOD WATCH SOUTH TO AREAS NORTH OF A FRANKLIN TO ROSWELL TO CLEVELAND LINE. FINALLY...ANOTHER LOW AMPLITUDE SHORT WAVE PROGGED TO MOVE ALONG LONG WAVE TROUGH OVER TN VALLEY THURS NIGHT. WITH COLD AIR IN PLACE...ESP ALOFT...COULD SEE SOME FLURRIES OR VERY LIGHT SNOW SHOWERS. NO IMPACTS EXPECTED. SNELSON LONG TERM /FRIDAY THROUGH TUESDAY/... EXTENDED MODELS IN FAIRLY GOOD AGREEMENT THROUGH THE LONG TERM...WITH LONG WAVE UPPER-LEVEL TROUGH SITUATED OVER THE EASTERN U.S. THOUGH EARLY NEXT WEEK. GENERALLY...NORTHWEST FLOW WILL PERSIST OVER THE REGION...AND MODELS CONTINUE TO ADVERTISE A SERIES OF UPPER LEVEL SHORT WAVES IMPACTING THE AREA AS A RESULT. THE FIRST DISTURBANCE OCCURS AT THE TAIL END OF THE SHORT TERM PERIODS...AND WHAT MOISTURE QUICKLY DISSIPATES INTO THE LONG TERM EARLY FRIDAY. THE SECOND DISTURBANCE LOOKS TO APPROACH THE AREA LATE SATURDAY AND REMAIN ACROSS FAR NORTH GEORGIA EARLY SUNDAY...WITH SLIGHTLY MORE MOISTURE AVAILABLE THAN THE PREVIOUS SHORTWAVE. FOR NOW...WITH THE LATEST MODEL TIMING FOR THIS SYSTEM...LOOKS LIKE IT WILL PRIMARILY BE RAIN...WITH SOME POSSIBILITY OF A RAIN-SNOW MIX INTO SUNDAY MORNING. HAVE GENERALLY GONE WITH SLIGHT CHANCE POPS...AND HAVE KEPT NO ACCUMULATIONS FOR NORTH GEORGIA. HAVE SCALED BACK POPS SLIGHTLY FOR THE THIRD SHORT WAVE EXPECTED MONDAY NIGHT INTO TUESDAY. LATEST MODEL RUNS ARE LESS ENTHUSIASTIC WITH THE FRONTAL SUPPORT...AND THEREFORE LESS AGGRESSIVE WITH MOISTURE AND PRECIP POTENTIAL. HAVE CONTINUED WITH SLIGHT CHANCE POPS MONDAY NIGHT AND TUESDAY...AND QUICKLY DROP POPS OFF INTO TUESDAY NIGHT. BELANGER FIRE WEATHER... AS DRY AIR PLUNGES IN BEHIND FRONT...HUMIDITY PROGGED TO DROP TO 22 TO 25 PCT FOR A FEW HOURS THURS AFTERNOON OVER MIDDLE GA. WITH 1 TO 2 INCHES OF RAIN EXPECTED TODAY...FUELS ARE EXPECTED TO BE TOO WET TO REQUIRE ANY FIRE DANGER STATEMENTS. SNELSON AVIATION... 12Z UPDATE... STILL MONITORING LINE OF STRONG TSRA THAT WILL MOVE ACROSS THE STATE TODAY AND THIS EVENING. TIMING HAS SHIFTED SLIGHTLY AND NOW APPEARS TSRA WILL AFFECT ATL METRO 19Z-23Z. EXPECT STRONG CROSSWIND AT E-W RUNWAY AIRPORTS TODAY...GUSTS COULD APPROACH 32KTS AT KATL. CIGS SHOULD STAY RIGHT NEAR IFR THRESHOLD AT KATL AND REMAIN JUST ABOVE IFR ELSEWHERE. EXPECT END TO CIGS AND PRECIP AROUND 23-00Z. STRONG WEST WINDS WILL CONTINUE OVERNIGHT AND THURS. //ATL CONFIDENCE...12Z UPDATE... MEDIUM CONFIDENCE ON IFR CIGS THIS MORNING. HIGH CONFIDENCE ON ALL OTHER ELEMENTS. SNELSON && .PRELIMINARY POINT TEMPS/POPS... ATHENS 71 38 50 33 / 100 100 5 5 ATLANTA 67 35 49 33 / 100 60 5 5 BLAIRSVILLE 61 32 43 27 / 100 60 5 20 CARTERSVILLE 67 34 47 31 / 100 40 5 10 COLUMBUS 72 38 56 39 / 100 70 5 5 GAINESVILLE 63 35 47 32 / 100 70 5 10 MACON 73 39 55 33 / 90 100 5 5 ROME 68 33 48 31 / 100 40 5 10 PEACHTREE CITY 68 36 51 32 / 100 60 5 5 VIDALIA 80 46 59 36 / 70 90 0 5 && .FFC WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR THE FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BARTOW...BIBB...BLECKLEY... BUTTS...CARROLL...CATOOSA...CHATTAHOOCHEE...CHATTOOGA... CHEROKEE...CLARKE...CLAYTON...COBB...COWETA...CRAWFORD...CRISP... DADE...DEKALB...DODGE...DOOLY...DOUGLAS...EMANUEL...FAYETTE... FLOYD...FORSYTH...GLASCOCK...GORDON...GREENE...GWINNETT...HALL... HANCOCK...HARALSON...HARRIS...HEARD...HENRY...HOUSTON... JACKSON...JASPER...JEFFERSON...JOHNSON...JONES...LAMAR... LAURENS...MACON...MADISON...MARION...MERIWETHER...MONROE... MONTGOMERY...MORGAN...MUSCOGEE...NEWTON...NORTH FULTON... OCONEE...OGLETHORPE...PAULDING...PEACH...PIKE...POLK...PULASKI... PUTNAM...ROCKDALE...SCHLEY...SOUTH FULTON...SPALDING...STEWART... SUMTER...TALBOT...TALIAFERRO...TAYLOR...TELFAIR...TOOMBS... TREUTLEN...TROUP...TWIGGS...UPSON...WALKER...WALTON...WARREN... WASHINGTON...WEBSTER...WHEELER...WHITFIELD...WILCOX...WILKES... WILKINSON. TORNADO WATCH UNTIL 4 PM EST THIS AFTERNOON FOR THE FOLLOWING ZONES: BALDWIN...BANKS...BARROW...BARTOW...BIBB...BLECKLEY... BUTTS...CARROLL...CATOOSA...CHATTAHOOCHEE...CHATTOOGA... CHEROKEE...CLARKE...CLAYTON...COBB...COWETA...CRAWFORD...DADE... DAWSON...DEKALB...DOOLY...DOUGLAS...FANNIN...FAYETTE...FLOYD... FORSYTH...GILMER...GORDON...GREENE...GWINNETT...HALL...HANCOCK... HARALSON...HARRIS...HEARD...HENRY...HOUSTON...JACKSON...JASPER... JONES...LAMAR...LUMPKIN...MACON...MADISON...MARION... MERIWETHER...MONROE...MORGAN...MURRAY...MUSCOGEE...NEWTON... NORTH FULTON...OCONEE...OGLETHORPE...PAULDING...PEACH... PICKENS...PIKE...POLK...PULASKI...PUTNAM...ROCKDALE...SCHLEY... SOUTH FULTON...SPALDING...STEWART...SUMTER...TALBOT... TALIAFERRO...TAYLOR...TOWNS...TROUP...TWIGGS...UNION...UPSON... WALKER...WALTON...WEBSTER...WHITE...WHITFIELD...WILKES... WILKINSON. HIGH WIND WARNING UNTIL 6 PM EST THIS EVENING FOR THE FOLLOWING ZONES: DAWSON...FANNIN...GILMER...LUMPKIN...MURRAY...PICKENS... TOWNS...UNION...WHITE. FLOOD WATCH THROUGH THIS EVENING FOR THE FOLLOWING ZONES: BARTOW...CATOOSA...CHATTOOGA...CHEROKEE...COBB...DADE...DAWSON... FANNIN...FLOYD...FORSYTH...GILMER...GORDON...HARALSON... LUMPKIN...MURRAY...NORTH FULTON...PAULDING...PICKENS...POLK... TOWNS...UNION...WALKER...WHITE...WHITFIELD. WIND ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT EST TONIGHT FOR THE FOLLOWING ZONES: DAWSON...FANNIN...GILMER...LUMPKIN... MURRAY...PICKENS...TOWNS...UNION...WHITE. && $$ SHORT TERM...ARG LONG TERM....31 AVIATION...ARG
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
209 PM CST WED JAN 30 2013 .DISCUSSION... 944 AM CST A WEAK SECONDARY SURFACE LOW IS MAKING ITS WAY THROUGH NORTHERN IL THIS MORNING WITH ARCTIC AIR SLOWLY SPILLING INTO WESTERN IL. FREEPORT IL HAS ALREADY TURNED OVER TO SNOW AND GETTING REPORTS OF RAIN MIXING WITH SLEET FROM DIXON AND ROCKFORD. AS TEMPS FALL TODAY EXPECTING RAIN TO QUICKLY CHANGE OVER TO SNOW WITH A BRIEF PERIOD OF SLEET/ICE PELLETS POSSIBLE. NOT EXPECTING ANY SIGNIFICANT IMPACTS FROM SLEET/ICE PELLETS. FOR THE WINTER WEATHER ADVISORY FOR WINNEBAGO...OGLE...AND BOONE COUNTIES...WILL KEEP IT GOING BUT THINKING THE BEST FORCING WILL OCCUR WHEN TEMPS ARE ABOVE FREEZING. THE UPPER LEVEL JET STREAKS LEFT EXIT REGION IS OVER NORTHERN IL WHILE THE SPC RAP AND OTHER GUIDANCE INDICATE A BAND OF 850 MB FRONTOGENESIS EXTENDING FROM SOUTHERN WI THROUGH MOLINE IL. NEGATIVE EPV LIES ABOVE THE FRONTOGENESIS WHICH WOULD SUPPORT BANDS OF LOCALLY HEAVIER SNOWFALL. HOWEVER...THE FRONTOGENESIS IS EXPECTED TO WEAKEN SIGNIFICANTLY THROUGH THE EARLY AFTERNOON HOURS SO THINKING THE HEAVIEST SNOW WILL FALL THROUGH 3PM AT THE LATEST ACROSS THE ADVISORY AREA. GIVEN THAT RAIN IS JUST TURNING OVER TO SNOW NOW...AGREE WITH THE PREVIOUS FORECAST THAT THE ADVISORY CRITERIA WILL PROBABLY ONLY BE MET IN ISOLATED LOCATIONS. OVERALL EXPECTING 2-4 INCHES OF SNOW IN THE ADVISORY AREA WITH LOCALLY HIGHER AMOUNTS POSSIBLE IF A MESOSCALE BAND SETS UP OVER THE AREA. AS TEMPS FALL THROUGH THE DAY RAIN WILL TURN OVER TO SNOW THROUGHOUT THE DAY. ROUGH TIMINGS ARE ALL SNOW ACROSS THE ADVISORY AREA BY NOON...NORTH OF I-55 BY 4-5 PM...CHICAGO BY 5-6 PM...AND ALL SNOW ACROSS THE AREA BY 7-8PM. EXPECTING A WET SNOW AS IT FIRST TURNS OVER THEN BECOMING A MORE AVERAGE SNOW LATE THIS AFTERNOON/EVENING. ONCE AGAIN EXPECTING 2-4 INCHES IN THE NORTHWEST CORNER OF THE CWA...1-2 INCHES NORTH OF A MENDOTA TO WAUKEGAN LINE...AND LESS THAN AN INCH ELSEWHERE. JEE //PREV DISCUSSION... 353 AM CST FORECAST CHALLENGES THIS MORNING INCLUDE POTENTIAL FOR SNOW TODAY...CLOUD COVER AND ITS POTENTIAL IMPACTS ON TEMPS...AND CLIPPER SYSTEM ARRIVING FRIDAY NIGHT INTO SATURDAY. VERY TRICKY FORECAST TODAY AS COLDER AIR SPILLS INTO THE REGION AND PORTIONS OF THE CWA POTENTIALLY GET CLIPPED BY TROWAL. HAVE OPTED TO ISSUE A WINTER WX ADVISORY FOR MY NW 3 COUNTIES MOSTLY DUE TO MODEL GUIDANCE AND TO MAKE A PRETTIER WATCH/WARNING/ADVISORY MAP BUT HAVE SERIOUS DOUBTS ABOUT WHETHER IT WILL COME CLOSE TO VERIFYING BASED ON CURRENT TRENDS IN OBSERVATIONAL DATA. WARM CONVEYOR BELT WITH ITS MASSIVE STREAM OF RAIN CONTINUES TO SHIFT EASTWARD AND OUT OF THE CWA EARLY THIS MORNING AND WOULD ANTICIPATE THIS TREND TO CONTINUE AS WATER VAPOR IMAGERY SHOWS MASSIVE DEVELOPING MID LEVEL DRY INTRUSION PUNCHING NORTHEAST INTO THE REGION. SURFACE ANALYSIS HAS ANOTHER IN SEEMING CONGA LINE OF LOWS OVER MISSOURI STILL AT 09Z...AS THIS LOW TRANSLATES NORTHEAST INTO ILLINOIS EARLY THIS MORNING IT WILL ACT TO SLOW THE INTRUSION OF COLD AIR AND LIKELY DELAY THE RAIN/SNOW TRANSITION LINE FROM MAKING GOOD HEADWAY ACROSS THE CWA UNTIL IT LIFTS OUT OF THE AREA TOWARD MIDDAY. PROFILERS AND OBJECTIVE ANALYSIS HAVE A 120KT+ 500MB JET PUNCHING NE INTO THE DRY INTRUSION WITH STRONG ASCENT TO THE LEFT OF THIS JET SUPPORTING AN INTENSIFYING TROWAL THIS MORNING OVER IOWA AND NORTHEAST MISSOURI. SUSPECT THAT THIS MORNING INTO THE EARLY AFTERNOON AS THE DRY INTRUSION MOVES IN THAT THE PREDOMINANT PRECIP TYPE WILL SHIFT TO DRIZZLE AND VERY LIGHT RAIN...THOUGH AS THE VORT NEAR MCI MOVES EAST COULD SEE SOME SHOWERS REDEVELOPING IMMEDIATELY IN ADVANCE OF THIS FEATURE. BY MIDDAY/EARLY AFTERNOON THE TROWAL OVER IOWA/NORTHWEST MO WILL BEGIN TO TRANSLATE EAST INTO NORTHERN ILLINOIS...BUT BY THAT POINT INSTABILITY WILL BE WEAKENING AND BECOMING MORE FOCUSED TO OUR NORTH. ALSO...STRONG SYNOPTIC ASCENT WILL ALSO BE SHIFTING NORTH INTO WI/MI AS THE MID LEVEL JET STREAK PUNCH NORTH INTO THE UPPER GREAT LAKES. SUSPECT THAT THIS WILL LEAVE OUR CWA WITH A GLANCING BLOW FROM THE DECAYING SOUTHERN FLANKS OF WHAT WILL BE A VERY HEALTHY TROWEL THIS MORNING. COMPUTER MODELS AND HPC GUIDANCE WOULD SUGGEST A SWATH OF 3 TO 5 INCHES OF SNOW ACROSS OUR NORTHWEST CWA WHERE I PLACED THE ADVISORY...WHILE WHAT I`M LOOKING AT IN OBSERVATIONAL DATA MAKE ME WONDER IF WE`LL BE ABLE TO SQUEEZE OUT EVEN 2 INCHES. AS A COMPROMISE WILL GO WITH 2 TO 4 INCHES "POSSIBLE" WORDING AND PUT OUT AN ADVISORY TO BLEND WITH NEIGHBORS AND ERR ON THE SIDE OF CAUTION...BUT DEFINITELY SEEING SOME BUST POTENTIAL IN THIS FORECAST. ACROSS THE REMAINDER OF THE CWA EXPECT DRIZZLY/SHOWERY WEATHER MUCH OF THE DAY WITH A TRANSITION FROM RAIN TO SNOW TAKING PLACE FROM NORTHWEST TO SOUTHEAST THIS AFTERNOON. SUPPOSE THERE COULD BE UP TO AN INCH OF ACCUMULATION FROM THE REMNANTS OF THE TROWAL BUT NOT LOOKING TO BE A TERRIBLY BIG DEAL. IN FACT...THE FALLING TEMPS AND BLUSTERY WINDS WILL PROBABLY BE THE BIGGER STORY FOR MOST. DEEP TROUGH THEN ESTABLISHES ITSELF OVER THE GREAT LAKES AND NORTHEAST FOR THE REMAINDER OF THE WEEK. FORECAST SOUNDINGS SHOW THE PRESENCE OF A STOUT FRONTAL INVERSION WHICH OFTEN TRAPS MOISTURE/STRATUS THIS TIME OF YEAR...PARTICULARLY WITH THE CYCLONIC LOW LEVEL FLOW FORECAST TO BE IN PLACE THROUGH THE REST OF THE WORK WEEK. GUIDANCE CONTINUE TO FORECAST H8 TEMPS DROPPING TO -20C OR A BIT COLDER BY THURSDAY AFTERNOON...SO CERTAINLY LOOKS TO BE A VERY FORMIDABLE SHOT OF ARCTIC AIR. HOWEVER...HAVE GENERALLY TRENDED TEMPS TOWARD THE WARMEST AVAILABLE GUIDANCE TONIGHT AS STRONG WINDS AND STRATUS ARE EXPECTED TO HELP KEEP TEMPS UP. AS SECONDARY SURGE OF ARCTIC AIR ARRIVES THURSDAY PROBABLY WILL SEE VERY LITTLE RECOVERY INTO TEMPS AND WITH CLOUDS LIKELY TO LINGER THURSDAY NIGHT AGAIN WENT WITH THE WARMER SIDE OF GUIDANCE. THE EXPECTED LACK OF SNOW COVER WOULD ALSO TEND TO SUPPORT NOT GOING AS COLD AS MOS NUMBERS FOR THIS TIME PERIOD. PRECIP WISE AFTER TODAY NOT ANTICIPATING ANY BIG PRECIP THREAT UNTIL FRIDAY NIGHT. HOWEVER...THE PRESENCE OF A STRATUS DECK WITH TEMPS FROM THE SFC TO 700MB PROGGED TO DROP INTO THE PRIME DENDRITIC GROWTH RANGE SUGGESTS THAT IT WILL TAKE VERY LITTLE FORCING FOR THIS DECK TO LEAK FLURRIES OR EVEN LIGHT SNOW. THE BEST CHANCE OF "FLAKY STRATUS" LOOKS TO BE THURSDAY INTO THURSDAY NIGHT AS THAT SECONDARY SURGE OF COLD AIR ARRIVES...BUT JUST ABOUT ANY WEAK IMPULSE PIVOTING AROUND THE TROUGH COULD BE ENOUGH TO PRODUCE SOME LIGHT SNOW OR FLURRIES. STRONGER CLIPPER IS STILL PROGGED TO ZIP SOUTHEAST INTO THE REGION FRIDAY NIGHT INTO SATURDAY AND GIVEN THE COLD AIR MASS IN PLACE COULD EASILY WRING OUT A SWATH OF A COUPLE/FEW INCHES OF SNOW. GUIDANCE STILL SUGGESTS THAT THE BEST CHANCES OF THIS WOULD BE IN OUR SOUTHERN CWA AND GIVEN A COUPLE DAYS OF CONSISTENCY IN THE MODELS HAVE GONE ABOVE GUIDANCE POPS AND NUDGED UP TO LOW END LIKELYS. OBVIOUSLY AS WE GET CLOSER TO THE EVENT THE TRACK COULD NEED TO BE NUDGED NORTH OR SOUTH...BUT DOES LOOKS LIKE SOMEWHERE IN THE NEIGHBORHOOD STANDS A DECENT SHOT OF SOME ACCUMULATING SNOW. A MODERATING TREND STILL APPEARS TO BE IN THE OFFING LATER IN THE WEEKEND INTO EARLY NEXT WEEK AS THE UPPER FLOW FLATTENS OUT. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * NW WINDS INCREASING THROUGH THE AFTN AND GUSTING TO 25-30 KT BY LATE AFTN AND EVENING. * AREAS OF RAIN/SNOW CHANGING TO ALL SNOW. VSBY BRIEFLY DOWN TO 1-3 MILES AT ORD THROUGH EARLY EVENING. * CONDITIONS IMPROVING TO MVFR CIG/VSBY THIS EVE. ALLSOPP //DISCUSSION...UPDATED 20Z... AREAS OF SNOW ARE MOVING ACROSS EASTERN IA AND NORTHERN IL...MAINLY DPA...ORD NORTHWARD. LESS IMPACT AT MDW. VSBY AT TIMES 1-3 MILES BUT THEN BOUNCING UP TO VFR. EXPECT A DUSTING TO 1/2 INCH ACCUMULATION. PREVIOUS DISCUSSION 18Z... WEAK LOW PRESSURE OVER CHICAGO AT NOON...WILL MOVE NORTHEAST ACROSS SOUTHERN LAKE MI THIS AFTERNOON. WINDS SHIFT NW IN THE WAKE OF THE LOW...AND LIGHT RAIN AND DRIZZLE MIXES WITH AND CHANGES TO SNOW. HOWEVER RADAR TRENDS SHOW THE BACK EDGE OF PRECIP LIFTING RAPIDLY NORTHEAST ABOUT THE TIME PRECIP CHANGES FROM RAIN TO SNOW...SO NO ACCUMULATION EXPECTED AT ORD OR MDW. IN FACT...VISIBILITY WILL IMPROVE RAPIDLY THIS AFTERNOON AS PRECIP ENDS AND COLDER DRIER AIR ARRIVES. IFR CIGS HAVE BEEN RUNNING AROUND 600 TO 800 FEET BUT SHOULD GRADUALLY IMPROVE TO MVFR AROUND 1000-1500 FT DURING THE AFTERNOON. CIGS SHOULD GRADUALLY LIFT TO AROUND 2000 FT OR BETTER THIS EVENING. AS CIGS AND VSBYS IMPROVE...NORTHWEST WINDS WILL BE PICKING UP THROUGH THE AFTERNOON. STRONG ARCTIC HIGH PRESSURE BUILDING INTO THE CENTRAL PLAINS WILL CREATE A TIGHT PRESSURE GRADIENT WHICH WILL PERSIST INTO THURSDAY NIGHT. BY MID TO LATE THIS AFTERNOON WINDS WILL BE 15-20 KT SUSTAINED WITH GUSTS 25-30 KT. WINDS MAY DIMINISH SLIGHTLY LATE TONIGHT EARLY THU MORNING...BUT GUSTS WILL PICK UP TO 25-30 AGAIN LATE MORNING AND AFTERNOON. ALLSOPP //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE IN WIND FORECAST. * LOW TO MEDIUM CONFIDENCE IN CIG/VSBY TRENDS WITH SNOW. LOTS OF VARIABILITY IN VSBY NEXT SEVERAL HOURS. * MEDIUM-HIGH CONFIDENCE IN IMPROVING CIG/VSBY THIS EVENING. ALLSOPP //OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z... THURSDAY NIGHT...VFR. FRIDAY...VFR...THEN MVFR AND A CHANCE OF SNOW OVERNIGHT. SATURDAY...MVFR BECOMING VFR. SUNDAY...VFR. MONDAY...VFR. TUESDAY...VFR. TRS && .MARINE... 208 PM CST ELONGATED AREA OF LOW PRESSURE STRETCHED FROM SOUTHERN LAKE MICHIGAN INTO SOUTHERN QUEBEC THIS AFTERNOON...WITH LOW PRESSURE CENTER OVER SOUTHWEST LOWER MICHIGAN EXPECTED TO DEEPEN AS IT LIFTS NORTHEAST AWAY FROM LAKE MICHIGAN TONIGHT. THE COMBINATION OF TIGHTENING SURFACE PRESSURE GRADIENT AND THE ADVECTION OF MUCH COLDER AIR BEHIND THE LOW WILL PROVIDE FOR NORTH-NORTHWEST GALES ACROSS THE LAKE TONIGHT. WINDS WILL GRADUALLY EASE BELOW GALE FORCE THURSDAY MORNING...THOUGH WITH CANADIAN HIGH PRESSURE BUILDING SOUTHEAST ACROSS THE PLAINS THE GRADIENT WILL REMAIN FAIRLY STOUT. THIS WILL KEEP WINDS IN THE 20-30 KT RANGE THROUGH THURSDAY NIGHT AND EARLY FRIDAY...THOUGH WITH A MORE-BACKED WEST-NORTHWEST DIRECTION. GIVEN THE EXPECTED PROGRESSION OF WIND TRENDS...THE CURRENT GALE WARNING FOR THE LAKE MICHIGAN OPEN WATERS APPEARS REASONABLE RUNNING THROUGH 9 AM CST THURSDAY...THOUGH COULD PERHAPS SEE A FEW GALE FORCE GUSTS LINGER ACROSS THE SOUTHEAST PART OF THE LAKE THROUGH LATE THURSDAY MORNING. TIMING OF THE GALE WARNING FOR INDIANA NEARSHORE ZONES ENDING AT 4 AM CST THURSDAY ALSO STILL APPEARS ON TRACK. SMALL CRAFT ADVISORIES WILL LIKELY NEED TO BE CARRIED THROUGH MUCH OF FRIDAY...PARTICULARLY FOR THE INDIANA NEARSHORE ZONES WHERE WAVES WILL BE SLOWEST TO COME DOWN IN PERSISTENT WEST-NORTHWEST FLOW. WINDS SHOULD DECREASE MORE MARKEDLY ACROSS THE LAKE BY FRIDAY AFTERNOON AS THE NORTHERN EXTENSION OF THE SURFACE HIGH PRESSURE RIDGE AXIS MOVES ACROSS THE AREA. A WEAK CLIPPER-TYPE LOW PRESSURE SYSTEM IS ANTICIPATED TO MOVE ACROSS THE MIDWEST SOUTH OF THE LAKES SATURDAY WHICH MAY RESULT IN SOME FLUCTUATION IN WIND DIRECTION DEPENDING ON DETAILS OF LOW TRACK...THOUGH WINDS SHOULD REMAIN LESS THAN 20 KTS. A SECOND STRONGER LOW WILL PASS ACROSS THE NORTHERN LAKES SATURDAY NIGHT...WHICH WILL RESULT IN ANOTHER FAIRLY SHORT PERIOD OF STRONGER 30 KT NORTHWEST WINDS LATER SATURDAY NIGHT INTO SUNDAY. WINDS WILL COME BACK DOWN AS HIGH PRESSURE RIDGING THEN MOVES IN QUICKLY AGAIN SUNDAY NIGHT. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ008 UNTIL 4 PM WEDNESDAY. IN...NONE. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 9 AM THURSDAY. SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 4 AM FRIDAY. GALE WARNING...INDIANA NEARSHORE WATERS UNTIL 4 AM THURSDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
157 PM CST WED JAN 30 2013 .DISCUSSION... 944 AM CST A WEAK SECONDARY SURFACE LOW IS MAKING ITS WAY THROUGH NORTHERN IL THIS MORNING WITH ARCTIC AIR SLOWLY SPILLING INTO WESTERN IL. FREEPORT IL HAS ALREADY TURNED OVER TO SNOW AND GETTING REPORTS OF RAIN MIXING WITH SLEET FROM DIXON AND ROCKFORD. AS TEMPS FALL TODAY EXPECTING RAIN TO QUICKLY CHANGE OVER TO SNOW WITH A BRIEF PERIOD OF SLEET/ICE PELLETS POSSIBLE. NOT EXPECTING ANY SIGNIFICANT IMPACTS FROM SLEET/ICE PELLETS. FOR THE WINTER WEATHER ADVISORY FOR WINNEBAGO...OGLE...AND BOONE COUNTIES...WILL KEEP IT GOING BUT THINKING THE BEST FORCING WILL OCCUR WHEN TEMPS ARE ABOVE FREEZING. THE UPPER LEVEL JET STREAKS LEFT EXIT REGION IS OVER NORTHERN IL WHILE THE SPC RAP AND OTHER GUIDANCE INDICATE A BAND OF 850 MB FRONTOGENESIS EXTENDING FROM SOUTHERN WI THROUGH MOLINE IL. NEGATIVE EPV LIES ABOVE THE FRONTOGENESIS WHICH WOULD SUPPORT BANDS OF LOCALLY HEAVIER SNOWFALL. HOWEVER...THE FRONTOGENESIS IS EXPECTED TO WEAKEN SIGNIFICANTLY THROUGH THE EARLY AFTERNOON HOURS SO THINKING THE HEAVIEST SNOW WILL FALL THROUGH 3PM AT THE LATEST ACROSS THE ADVISORY AREA. GIVEN THAT RAIN IS JUST TURNING OVER TO SNOW NOW...AGREE WITH THE PREVIOUS FORECAST THAT THE ADVISORY CRITERIA WILL PROBABLY ONLY BE MET IN ISOLATED LOCATIONS. OVERALL EXPECTING 2-4 INCHES OF SNOW IN THE ADVISORY AREA WITH LOCALLY HIGHER AMOUNTS POSSIBLE IF A MESOSCALE BAND SETS UP OVER THE AREA. AS TEMPS FALL THROUGH THE DAY RAIN WILL TURN OVER TO SNOW THROUGHOUT THE DAY. ROUGH TIMINGS ARE ALL SNOW ACROSS THE ADVISORY AREA BY NOON...NORTH OF I-55 BY 4-5 PM...CHICAGO BY 5-6 PM...AND ALL SNOW ACROSS THE AREA BY 7-8PM. EXPECTING A WET SNOW AS IT FIRST TURNS OVER THEN BECOMING A MORE AVERAGE SNOW LATE THIS AFTERNOON/EVENING. ONCE AGAIN EXPECTING 2-4 INCHES IN THE NORTHWEST CORNER OF THE CWA...1-2 INCHES NORTH OF A MENDOTA TO WAUKEGAN LINE...AND LESS THAN AN INCH ELSEWHERE. JEE //PREV DISCUSSION... 353 AM CST FORECAST CHALLENGES THIS MORNING INCLUDE POTENTIAL FOR SNOW TODAY...CLOUD COVER AND ITS POTENTIAL IMPACTS ON TEMPS...AND CLIPPER SYSTEM ARRIVING FRIDAY NIGHT INTO SATURDAY. VERY TRICKY FORECAST TODAY AS COLDER AIR SPILLS INTO THE REGION AND PORTIONS OF THE CWA POTENTIALLY GET CLIPPED BY TROWAL. HAVE OPTED TO ISSUE A WINTER WX ADVISORY FOR MY NW 3 COUNTIES MOSTLY DUE TO MODEL GUIDANCE AND TO MAKE A PRETTIER WATCH/WARNING/ADVISORY MAP BUT HAVE SERIOUS DOUBTS ABOUT WHETHER IT WILL COME CLOSE TO VERIFYING BASED ON CURRENT TRENDS IN OBSERVATIONAL DATA. WARM CONVEYOR BELT WITH ITS MASSIVE STREAM OF RAIN CONTINUES TO SHIFT EASTWARD AND OUT OF THE CWA EARLY THIS MORNING AND WOULD ANTICIPATE THIS TREND TO CONTINUE AS WATER VAPOR IMAGERY SHOWS MASSIVE DEVELOPING MID LEVEL DRY INTRUSION PUNCHING NORTHEAST INTO THE REGION. SURFACE ANALYSIS HAS ANOTHER IN SEEMING CONGA LINE OF LOWS OVER MISSOURI STILL AT 09Z...AS THIS LOW TRANSLATES NORTHEAST INTO ILLINOIS EARLY THIS MORNING IT WILL ACT TO SLOW THE INTRUSION OF COLD AIR AND LIKELY DELAY THE RAIN/SNOW TRANSITION LINE FROM MAKING GOOD HEADWAY ACROSS THE CWA UNTIL IT LIFTS OUT OF THE AREA TOWARD MIDDAY. PROFILERS AND OBJECTIVE ANALYSIS HAVE A 120KT+ 500MB JET PUNCHING NE INTO THE DRY INTRUSION WITH STRONG ASCENT TO THE LEFT OF THIS JET SUPPORTING AN INTENSIFYING TROWAL THIS MORNING OVER IOWA AND NORTHEAST MISSOURI. SUSPECT THAT THIS MORNING INTO THE EARLY AFTERNOON AS THE DRY INTRUSION MOVES IN THAT THE PREDOMINANT PRECIP TYPE WILL SHIFT TO DRIZZLE AND VERY LIGHT RAIN...THOUGH AS THE VORT NEAR MCI MOVES EAST COULD SEE SOME SHOWERS REDEVELOPING IMMEDIATELY IN ADVANCE OF THIS FEATURE. BY MIDDAY/EARLY AFTERNOON THE TROWAL OVER IOWA/NORTHWEST MO WILL BEGIN TO TRANSLATE EAST INTO NORTHERN ILLINOIS...BUT BY THAT POINT INSTABILITY WILL BE WEAKENING AND BECOMING MORE FOCUSED TO OUR NORTH. ALSO...STRONG SYNOPTIC ASCENT WILL ALSO BE SHIFTING NORTH INTO WI/MI AS THE MID LEVEL JET STREAK PUNCH NORTH INTO THE UPPER GREAT LAKES. SUSPECT THAT THIS WILL LEAVE OUR CWA WITH A GLANCING BLOW FROM THE DECAYING SOUTHERN FLANKS OF WHAT WILL BE A VERY HEALTHY TROWEL THIS MORNING. COMPUTER MODELS AND HPC GUIDANCE WOULD SUGGEST A SWATH OF 3 TO 5 INCHES OF SNOW ACROSS OUR NORTHWEST CWA WHERE I PLACED THE ADVISORY...WHILE WHAT I`M LOOKING AT IN OBSERVATIONAL DATA MAKE ME WONDER IF WE`LL BE ABLE TO SQUEEZE OUT EVEN 2 INCHES. AS A COMPROMISE WILL GO WITH 2 TO 4 INCHES "POSSIBLE" WORDING AND PUT OUT AN ADVISORY TO BLEND WITH NEIGHBORS AND ERR ON THE SIDE OF CAUTION...BUT DEFINITELY SEEING SOME BUST POTENTIAL IN THIS FORECAST. ACROSS THE REMAINDER OF THE CWA EXPECT DRIZZLY/SHOWERY WEATHER MUCH OF THE DAY WITH A TRANSITION FROM RAIN TO SNOW TAKING PLACE FROM NORTHWEST TO SOUTHEAST THIS AFTERNOON. SUPPOSE THERE COULD BE UP TO AN INCH OF ACCUMULATION FROM THE REMNANTS OF THE TROWAL BUT NOT LOOKING TO BE A TERRIBLY BIG DEAL. IN FACT...THE FALLING TEMPS AND BLUSTERY WINDS WILL PROBABLY BE THE BIGGER STORY FOR MOST. DEEP TROUGH THEN ESTABLISHES ITSELF OVER THE GREAT LAKES AND NORTHEAST FOR THE REMAINDER OF THE WEEK. FORECAST SOUNDINGS SHOW THE PRESENCE OF A STOUT FRONTAL INVERSION WHICH OFTEN TRAPS MOISTURE/STRATUS THIS TIME OF YEAR...PARTICULARLY WITH THE CYCLONIC LOW LEVEL FLOW FORECAST TO BE IN PLACE THROUGH THE REST OF THE WORK WEEK. GUIDANCE CONTINUE TO FORECAST H8 TEMPS DROPPING TO -20C OR A BIT COLDER BY THURSDAY AFTERNOON...SO CERTAINLY LOOKS TO BE A VERY FORMIDABLE SHOT OF ARCTIC AIR. HOWEVER...HAVE GENERALLY TRENDED TEMPS TOWARD THE WARMEST AVAILABLE GUIDANCE TONIGHT AS STRONG WINDS AND STRATUS ARE EXPECTED TO HELP KEEP TEMPS UP. AS SECONDARY SURGE OF ARCTIC AIR ARRIVES THURSDAY PROBABLY WILL SEE VERY LITTLE RECOVERY INTO TEMPS AND WITH CLOUDS LIKELY TO LINGER THURSDAY NIGHT AGAIN WENT WITH THE WARMER SIDE OF GUIDANCE. THE EXPECTED LACK OF SNOW COVER WOULD ALSO TEND TO SUPPORT NOT GOING AS COLD AS MOS NUMBERS FOR THIS TIME PERIOD. PRECIP WISE AFTER TODAY NOT ANTICIPATING ANY BIG PRECIP THREAT UNTIL FRIDAY NIGHT. HOWEVER...THE PRESENCE OF A STRATUS DECK WITH TEMPS FROM THE SFC TO 700MB PROGGED TO DROP INTO THE PRIME DENDRITIC GROWTH RANGE SUGGESTS THAT IT WILL TAKE VERY LITTLE FORCING FOR THIS DECK TO LEAK FLURRIES OR EVEN LIGHT SNOW. THE BEST CHANCE OF "FLAKY STRATUS" LOOKS TO BE THURSDAY INTO THURSDAY NIGHT AS THAT SECONDARY SURGE OF COLD AIR ARRIVES...BUT JUST ABOUT ANY WEAK IMPULSE PIVOTING AROUND THE TROUGH COULD BE ENOUGH TO PRODUCE SOME LIGHT SNOW OR FLURRIES. STRONGER CLIPPER IS STILL PROGGED TO ZIP SOUTHEAST INTO THE REGION FRIDAY NIGHT INTO SATURDAY AND GIVEN THE COLD AIR MASS IN PLACE COULD EASILY WRING OUT A SWATH OF A COUPLE/FEW INCHES OF SNOW. GUIDANCE STILL SUGGESTS THAT THE BEST CHANCES OF THIS WOULD BE IN OUR SOUTHERN CWA AND GIVEN A COUPLE DAYS OF CONSISTENCY IN THE MODELS HAVE GONE ABOVE GUIDANCE POPS AND NUDGED UP TO LOW END LIKELYS. OBVIOUSLY AS WE GET CLOSER TO THE EVENT THE TRACK COULD NEED TO BE NUDGED NORTH OR SOUTH...BUT DOES LOOKS LIKE SOMEWHERE IN THE NEIGHBORHOOD STANDS A DECENT SHOT OF SOME ACCUMULATING SNOW. A MODERATING TREND STILL APPEARS TO BE IN THE OFFING LATER IN THE WEEKEND INTO EARLY NEXT WEEK AS THE UPPER FLOW FLATTENS OUT. IZZI && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * NW WINDS INCREASING THROUGH THE AFTN AND GUSTING TO 25-30 KT BY LATE AFTN AND EVENING. * AREAS OF RAIN/SNOW CHANGING TO ALL SNOW. VSBY BRIEFLY DOWN TO 1-3 MILES AT ORD THROUGH EARLY EVENING. * CONDITIONS IMPROVING TO MVFR CIG/VSBY THIS EVE. ALLSOPP //DISCUSSION...UPDATED 20Z... AREAS OF SNOW ARE MOVING ACROSS EASTERN IA AND NORTHERN IL...MAINLY DPA...ORD NORTHWARD. LESS IMPACT AT MDW. VSBY AT TIMES 1-3 MILES BUT THEN BOUNCING UP TO VFR. EXPECT A DUSTING TO 1/2 INCH ACCUMULATION. PREVIOUS DISCUSSION 18Z... WEAK LOW PRESSURE OVER CHICAGO AT NOON...WILL MOVE NORTHEAST ACROSS SOUTHERN LAKE MI THIS AFTERNOON. WINDS SHIFT NW IN THE WAKE OF THE LOW...AND LIGHT RAIN AND DRIZZLE MIXES WITH AND CHANGES TO SNOW. HOWEVER RADAR TRENDS SHOW THE BACK EDGE OF PRECIP LIFTING RAPIDLY NORTHEAST ABOUT THE TIME PRECIP CHANGES FROM RAIN TO SNOW...SO NO ACCUMULATION EXPECTED AT ORD OR MDW. IN FACT...VISIBILITY WILL IMPROVE RAPIDLY THIS AFTERNOON AS PRECIP ENDS AND COLDER DRIER AIR ARRIVES. IFR CIGS HAVE BEEN RUNNING AROUND 600 TO 800 FEET BUT SHOULD GRADUALLY IMPROVE TO MVFR AROUND 1000-1500 FT DURING THE AFTERNOON. CIGS SHOULD GRADUALLY LIFT TO AROUND 2000 FT OR BETTER THIS EVENING. AS CIGS AND VSBYS IMPROVE...NORTHWEST WINDS WILL BE PICKING UP THROUGH THE AFTERNOON. STRONG ARCTIC HIGH PRESSURE BUILDING INTO THE CENTRAL PLAINS WILL CREATE A TIGHT PRESSURE GRADIENT WHICH WILL PERSIST INTO THURSDAY NIGHT. BY MID TO LATE THIS AFTERNOON WINDS WILL BE 15-20 KT SUSTAINED WITH GUSTS 25-30 KT. WINDS MAY DIMINISH SLIGHTLY LATE TONIGHT EARLY THU MORNING...BUT GUSTS WILL PICK UP TO 25-30 AGAIN LATE MORNING AND AFTERNOON. ALLSOPP //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE IN WIND FORECAST. * LOW TO MEDIUM CONFIDENCE IN CIG/VSBY TRENDS WITH SNOW. LOTS OF VARIABILITY IN VSBY NEXT SEVERAL HOURS. * MEDIUM