Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 02/16/13


AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
826 PM MST FRI FEB 15 2013 .UPDATE...FORECAST RIGHT ON TRACK. SKIES WILL GRADUALLY CLEAR OVERNIGHT AND OCCASIONAL GUSTY WINDS SHOULD REDEVELOP IN/NEAR FOOTHILLS AS MOUNTAIN TOP STABLE LAYER STRENGTHENS. SUNNY AND BREEZY CONDITIONS WILL SPREAD OVER MOST OF THE FORECAST AREA SATURDAY WITH MUCH WARMER TEMPERATURES. && .AVIATION...WINDS WERE TURNING TO SOUTHERLY WITH NORMAL SOUTH/SOUTHWEST WINDS AT KDEN AND KAPA EXPECTED OVERNIGHT. STILL POTENTIAL GUSTY WINDS DEVELOPING AT KBJC AFTER 08Z-10Z WITH STRENGTHENING MOUNTAIN TOP STABLE LAYER...BUT LACK OF FLOW COULD LIMIT POTENTIAL GUSTS TO 30 KTS. WITH SUNNY SKIES AND BETTER MIXING ON SATURDAY...RELATIVELY HIGH CHANCE THAT GUSTY WEST/NORTHWEST WINDS UP TO 20-25 KTS WILL SPREAD TO KDEN AND KAPA BY 20Z-21Z SATURDAY. && .PREV DISCUSSION... /ISSUED 329 PM MST FRI FEB 15 2013/ SHORT TERM...WEAK SHORTWAVE IN NORTHWEST FLOW ALOFT CLIPPING NORTHEAST PLAINS OF COLORADO AT PRESENT TIME. RADAR INDICATING A FEW LIGHT SHOWERS MOVING SOUTHEAST ACROSS WASHINGTON AND ELBERT COUNTIES ON BACK EDGE OF THE MID LEVEL ASCENT. DOESN`T APPEAR MUCH IS REACHING THE GROUND BASED ON WEB CAMS AND SURFACE OBS. ENOUGH MIXING BEHIND SURGE HAS HELPED TO PRODUCE GUSTY WINDS ACROSS MUCH OF PLAINS WITH SOME GUSTS NEAR 40 MPH FROM DENVER NORTH TOWARD THE WYOMING BORDER. OVER THE MOUNTAINS...WEB CAMS STILL SHOWING LIGHT SNOW ALONG THE CONTINENTAL DIVIDE OF SUMMIT AND GRAND COUNTIES... THOUGH HAS BEEN SHOWING SIGNS OF DECREASING DURING THE PAST COUPLE OF HOURS. GUSTY WINDS ALSO OCCURRING ACROSS THE MOUNTAINS AND ALONG THE FOOTHILLS. LATEST RAP SHOWS MOISTURE DEPTH DECREASING DURING THE EVENING ACROSS THE MOUNTAINS. DESPITE CONTINUED OROGRAPHICS...SHOULD SEE SNOW DECREASE THROUGH THE EVENING AND COME TO AN END AROUND MIDNIGHT AS MID LEVEL WARMING INCREASES AND LAPSE RATES DECREASE. ANY ADDITIONAL ACCUMULATIONS WILL BE LIGHT. MID LEVEL WARMING TO DEVELOP MOUNTAIN WAVE BY MIDNIGHT. INCREASING SUBSIDENCE WILL HELP WITH DOWNWARD MOMENTUM TO INCREASE WINDS ACROSS MOUNTAINS AND ALONG FOOTHILLS. DOES NOT LOOK LIKE A HIGH WIND SITUATION AS CROSS MOUNTAIN FLOW EXPECTED TO BE AROUND 40 KTS. MODELS SHOW SOME HINTS OF THE WAVE WEAKENING AFTER MIDNIGHT...WITH PERHAPS A DECREASE IN THE SPEEDS. ACROSS THE PLAINS...WINDS TO GRADUALLY DECREASE DURING THE EVENING AS SURFACE GRADIENT WEAKENS...THOUGH MAY REMAIN GUSTY NEAR THE BASE OF THE FOOTHILLS AND FAR EASTERN PLAINS. OVERNIGHT TEMPERATURES TO BE SLIGHTLY WARMER MOST AREAS DUE TO THE WARM AIR ADVECTION AND WIND. HOWEVER...LOW LYING AREAS BELOW THE MID LEVEL INVERSION TO BE MUCH COLDER WITH PERHAPS BELOW ZERO READINGS IN THE VALLEYS OF GRAND AND JACKSON COUNTIES. ON SATURDAY...NORTHWEST FLOW ALOFT TO CONTINUE AS UPPER RIDGE BUILDS ACROSS THE GREAT BASIN...THOUGH GRADIENT WILL BE WEAKER. SO WINDS TO BE LIGHTER...THOUGH WILL STILL BE A BIT GUSTY ACROSS THE MOUNTAINS AND HIGHER FOOTHILLS. SOME MIXING POSSIBLE OVER THE PLAINS COULD CREATE SOME GUSTY NORTHWEST WINDS DURING THE AFTERNOON. HIGHS TO WARM INTO THE 50S ACROSS THE PLAINS. LONG TERM...ON SATURDAY NIGHT...AN UPPER LEVEL TROUGH WILL BE OVER THE NORTHERN ROCKIES WHILE A WEAK RIDGE MOVES ACROSS COLORADO. THIS IS EXPECTED TO BRING DRY CONDITIONS SATURDAY NIGHT AND FOR MOST OF SUNDAY. COULD SEE A FEW LIGHT SNOW SHOWERS LATE SUNDAY AFTERNOON OVER THE MOUNTAINS OF NORTH CENTRAL COLORADO AS THE UPPER LEVEL TROUGH OVER THE NORTHERN ROCKIES SHIFTS EAST-SOUTHEAST. A SURFACE LOW WILL FORM OVER SOUTHEAST COLORADO SUNDAY IN ADVANCE OF THE TROUGH. THIS WILL CAUSE WINDS TO TURN NORTHERLY OVER NORTHEAST COLORADO SUNDAY AFTERNOON. EXPECT THIS TO START PULLING IN COOLER AIR SO DROPPED HIGHS FOR SUNDAY A FEW DEGREES. HOWEVER...IT WILL STILL BE MILD WITH HIGHS IN THE 50S. THE BASE OF THE TROUGH WILL MOVE ACROSS WYOMING AND NORTHERN COLORADO SUNDAY NIGHT AND EARLY MONDAY. THIS WILL LIKELY BRING A SHOT OF LIGHT SNOW TO THE MOUNTAINS. FOR THE FRONT RANGE...NOT A FAVORABLE SET UP BUT WINDS MAY TURN UPSLOPE FOR LONG ENOUGH TO PRODUCE LIGHT SNOW ALONG THE FRONT RANGE. THE PLAINS MAY SEE A LIGHT DUSTING AT BEST. SNOW MAY LINGER INTO MONDAY MORNING OVER THE MOUNTAINS AND PALMER DIVIDE BEFORE DRIER MOVES IN FOR MONDAY AFTERNOON. A WEAK RIDGE WILL KEEP DRY CONDITIONS OVER COLORADO MONDAY NIGHT AND TUESDAY. HIGHS WILL BE NEAR NORMAL TUESDAY WITH READINGS IN THE 40S. A DEEP TROUGH WILL MOVE ONTO THE CALIFORNIA COAST TUESDAY. GENERAL PATTERN HAS BEEN CONSISTENT FOR THE PAST FEW DAYS WITH THIS DEEP TROUGH CLOSING OFF AND MOVING ACROSS THE GREAT BASIN AND THEN THE ROCKIES BY MID TO LATE WEEK. DETAILS ON TRACK DEVELOPMENT STILL NEEDS TO BE WORKED OUT. TEMPERATURES WILL BE COOL WITH MOST PLACES SEEING PRECIPITATION SOMETIME LATE WEDNESDAY THROUGH THURSDAY. MANY OF THE MODELS ARE SHOWING A CLOSED LOW LIFTING NORTHEAST ACROSS UTAH ON WEDNESDAY AND THEN REFORMING THE MAIN LOW OVER SOUTHEAST COLORADO BY THURSDAY MORNING. THIS WOULD WORK AGAINST HEAVY SNOW FOR THE FRONT RANGE. ONCE THE LOW REFORMS OVER SOUTHEAST COLORADO...IT WILL THEN LIFT NORTHEAST ACROSS THE CENTRAL PLAINS WHERE IT WILL LIKELY PRODUCE BLIZZARD CONDITIONS THURSDAY AND THURSDAY NIGHT. WILL HAVE THE HIGHEST POPS OVER THE COLORADO EASTERN PLAINS BECAUSE OF THIS. EXPECT COOL CONDITIONS TO PREVAIL FRIDAY BECAUSE OF A LONG WAVE TROUGH STILL OVER THE WESTERN U.S. A WEAKER TROUGH WILL BE OVER THE GREAT BASIN FRIDAY AND WILL HAVE LOW POPS IN THE MOUNTAINS FOR THIS SYSTEM. AVIATION...GUSTY NORTHERLY WINDS AT DEN BEGINNING TO SHOW SOME SIGNS OF DECREASING AND SHIFTING TO THE NORTHEAST. GRADIENT WEAKER AND BJC AND APA. CEILINGS HAVE INCREASED TO ABOVE 7000 FEET AGL WITH VFR PREVAILING. WINDS TO CONTINUE TO WEAKEN ACROSS THE AREA AIRPORTS...BECOMING SOUTHEAST AROUND 03Z. SOUTHWEST DRAINAGE WINDS TO THEN DEVELOP BY 06Z...THOUGH MAY BE MORE WESTERLY AT BJC. POSSIBLE MOUNTAIN WAVE OVER FRONT RANGE OVERNIGHT WITH POTENTIAL GUSTS TO 40 KTS AT BJC. WINDS TO SHIFT TO THE NORTHWEST AT 15Z SATURDAY. SOME GUSTS TO 20 KTS POSSIBLE AT DEN. VFR TO CONTINUE WITH UNLIMITED CEILINGS. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...BARJENBRUCH LONG TERM....MEIER AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS PUEBLO CO
308 PM MST THU FEB 14 2013 .SHORT TERM...(TONIGHT AND TOMORROW) ISSUED AT 308 PM MST THU FEB 14 2013 A FAST MOVING COLD FRONT HAS MOVED SOUTH OF HIGHWAY 50. THE FRONT SHOULD CLEAR THE CO/NM BORDER BY 22Z. THE HRRR AND RAP PROG ANY LINGERING SNOW SHOWERS TO END BY MIDNIGHT ACROSS THE AREA. HOWEVER...THE NAM12 AND GFS ARE HOLDING ON TO SNOW SHOWERS THROUGH 12Z ACROSS THE SOUTHERN I-25 CORRIDOR. DECIDED TO LEAVE SOME 15 TO 35 POPS SOUTH AND WEST OF TAD IN THE GRIDS. DUE TO TO THE FAST MOVEMENT OF THE FRONT/PRECIP...LITTLE TO NO ACCUMULATIONS ARE EXPECTED UNDER ANY OF THE SNOW SHOWERS EAST OF THE CONTINENTAL DIVIDE. GUSTY NORTHEAST WINDS WILL BEGIN TO RELAX AFTER 02Z. WEST OF THE I-25 CORRIDOR...LIGHT SNOW SHOWERS WILL CONTINUE IN AND AROUND THE LEADVILLE AREA OVERNIGHT INTO TOMORROW MORNING. THE SAN LUIS VALLEY WILL BE MOSTLY CLEAR...COLD...AND DRY OVERNIGHT FRIDAY...MODELS CONTINUE TO SHOW LIGHT SNOW SHOWERS IN THE LEADVILLE AREA THROUGH FRIDAY AFTERNOON AND HAVE KEPT POPS IN PLACE AS PREVIOUSLY FORECASTED. 700MB TEMPERATURES WILL FALLING TO -11 TO -13.5C WILL KEEP HIGH TEMPERATURES 3-5 DEGREES COOLER ACROSS MOST LOCATIONS FRIDAY AFTERNOON. A FEW LINGERING CLOUDS ACROSS THE AREA WILL ALSO HELP TO CAP HIGH TEMPERATURES TOMORROW AFTERNOON. -PJC .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 308 PM MST THU FEB 14 2013 (FRIDAY NIGHT-THURSDAY) FRIDAY NIGHT-SUNDAY...STRONG NORTH TO NORTHWEST FLOW ALOFT ACROSS THE REGION FRIDAY NIGHT MODERATES AND BECOMES MORE WESTERLY THROUGH THE DAY SUNDAY AS UPPER LEVEL RIDGING BUILDING ACROSS THE GREAT BASIN FLATTENS ACROSS THE STATE AHEAD OF MORE SHORT WAVE ENERGY MOVING ONSHORE ACROSS THE PAC NORTHWEST COAST. DRY WEATHER WITH WELL ABOVE SEASONAL TEMPERATURES EXPECTED THROUGH THE FIRST PART OF THE HOLIDAY WEEKEND...WITH BREEZY WEST WINDS ACROSS THE HIGHER TERRAIN AND IMMEDIATE ADJACENT PLAINS SATURDAY AND SATURDAY NIGHT. SHOULD SEE INCREASING HIGH CLOUDS FROM WEST TO EAST THROUGH THE DAY SUNDAY AS THE SYSTEM CONTINUES TO MOVE ACROSS THE GREAT BASIN. SUNDAY NIGHT-MONDAY NIGHT...STILL SOME MODEL DIFFERENCES ON AMPLITUDE OF GREAT BASIN SYSTEM MOVING ACROSS THE ROCKIES WITH THE 12Z GFS STILL DIGGING FURTHER SOUTH THAN THE ECMWF...HOWEVER THE GFS HAS STARTED TO TREND FURTHER NORTH AND IS WEAKER WITH THE SYSTEM THAN PREVIOUS RUNS. WITH THAT SAID...SHOULD STILL SEE A HEALTHY COLD FRONT WITH A 10-20 DEGREE DROP IN TEMPERATURES FROM SUNDAY...MOST NOTICEABLE ACROSS EASTERN COLORADO. HAVE ALSO KEPT ISOLATED TO SCATTERED POPS INTACT ACROSS THE HIGHER TERRAIN AND IMMEDIATE ADJACENT PLAINS...WITH NOT MUCH PRECIPITATION EXPECTED...ESPECIALLY IF THE SYSTEM CONTINUES TO TREND FURTHER NORTH. TUESDAY-THURSDAY...WARMER WESTERLY FLOW PROGGED ACROSS THE AREA TUESDAY WITH INCREASING SOUTHWEST FLOW TUESDAY NIGHT AND WEDNESDAY AHEAD OF A STRONGER SYSTEM MOVING INTO THE GREAT BASIN. SOME DIFFERENCES IN MOVEMENT OF THIS SYSTEM WITH THE GFS LIFTING IT ACROSS SOUTH CENTRAL COLORADO WEDNESDAY NIGHT AND INTO THE NORTHWEST KANSAS ON THURSDAY. THE LATEST EC IS A TAD FURTHER SOUTH WITH THE SYSTEM ACROSS SOUTHWEST KANSAS ON THURSDAY...WHICH PRODUCES BETTER CHANCES OF SNOW AND BLOWING SNOW ACROSS THE SOUTHEAST PLAINS NORTH OF HIGHWAY 50...ESPECIALLY AREAS ALONG THE PALMER DVD. AT ANY RATE...MODEL CONSENSUS IS FAIRLY CONSERVATIVE THIS FAR OUT AND HAVE INCREASED POPS TO CHANCES ALONG THE CONTDVD FOR THE WEDNESDAY THROUGH EARLY THURSDAY PERIODS. HAVE ALSO INCREASED POPS TO SLIGHT CHANCES ACROSS PORTIONS OF THE PLAINS. THIS SYSTEM WILL LIKELY PRODUCE SIGNIFICANT WEATHER SOMEWHERE ACROSS THE REGION...THOUGH TIME WILL TELL AS TO EXACTLY WHERE. -MW && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING) ISSUED AT 308 PM MST THU FEB 14 2013 VFR CONDITIONS ARE EXPECTED AT ALL THREE TAF SITES...KALS...KCOS...AND KPUB THROUGH TOMORROW AFTERNOON WITH AN OCCASIONAL DROP TO MVFR CONDITIONS AT KCOS EARLY THIS EVENING DUE TO LIGHT SNOW SHOWER ACTIVITY IN THE AREA. GUSTY WINDS FROM THE NORTH AND NORTHEAST WILL DIMINISH LATER THIS EVENING. -PJC && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...PJC LONG TERM...MW AVIATION...PJC
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
939 AM MST THU FEB 14 2013 .UPDATE... && .SHORT TERM...CURRENT FORECASTS STILL SEEM ON TRACK AS UPPER TROUGH MOVES ACROSS COLORADO. LATEST MODELS CONTINUE TO SHOW DECENT MID LEVEL QG ASCENT SPREADING ACROSS THE AREA THROUGH THE AFTERNOON. WEB CAMS ACROSS MOUNTAINS CONTINUE TO SNOW LIGHT SNOW ACROSS MUCH OF THE AREA...DOESN`T APPEAR TOO HEAVY AT THIS TIME. SNOW WILL CONTINUE THROUGH THE EVENING...WITH AMOUNTS LESS THAN ADVISORY CRITERIA. ACROSS PLAINS...FRONT CURRENTLY MOVING SOUTH ACROSS EASTERN LARIMER AND CENTRAL WELD COUNTIES...EXTENDING INTO SOUTHERN MORGAN AND SOUTHERN WASHINGTON COUNTIES. RADAR SHOWING BAND OF PRECIP ALONG AND NORTH OF THE FRONT. WEB CAMS IN THIS AREA NOT SHOWING MUCH REACHING THE GROUND ALONG THE FRONT. FRONT TO MOVE SOUTH DURING THE MORNING...WITH PRECIP SPREADING SOUTH AND WEST. LATEST MODELS STILL POINTING AREAS ALONG FOOTHILLS AND WESTERN SECTIONS OF URBAN CORRIDOR FOR THE HIGHER SNOW AMOUNTS THROUGH THE AFTERNOON AS SEVERAL BANDS APPEAR TO CONVERGE IN THIS AREA. OVERALL...LIGHT SNOW AMOUNTS STILL ON TRACK...WITH A GENERAL 1 TO 3 INCHES IN AND NEAR FOOTHILLS...WITH LESS AMOUNTS EASTWARD. WILL NEED TO WATCH FOR ANY BANDS PARKING IN ONE AREA FOR AN EXTENDED PERIOD WHICH COULD INCREASE SNOW AMOUNTS...AT THIS TIME THE CHANCES OF THIS OCCURRING IS LOW. WILL ALSO NEED TO WATCH AN AREA FROM EASTERN MORGAN COUNTY INTO WASHINGTON COUNTY AS THE LATEST NAM AND THE LOCAL CAIC WRF RUC SUGGESTING A BAND OF 1 TO 3 INCHES IN THIS AREA BY 00Z. .AVIATION...CURRENT TAF TRENDS STILL SEEM ON TRACK. FRONT AND LEADING EDGE OF PRECIP BAND JUST NORTH AND EAST OF DIA...SLOWING SAGGING SOUTHWARD. WINDS AT DIA NOW SHOWING SIGNS OF A NORTHEAST DIRECTION. FRONT AND PRECIP TO SPREAD ACROSS THE DENVER AREA THROUGH THE MORNING. CEILINGS AND VISIBILITY TO LOWER BY 18Z WITH ILS CONDITIONS A GOOD BET. MVFR CONDITIONS TO PREVAIL BETWEEN 18Z AND 03Z WITH POSSIBLE IFR CONDITIONS. ANY SNOW ACCUMULATIONS STILL EXPECTED TO BE LESS THAN AN INCH. CONDITIONS TO GRADUALLY IMPROVE AFTER 03Z BUT CEILINGS SHOULD REMAIN BELOW 7000 FEET AGL. && .PREV DISCUSSION... /ISSUED 330 AM MST THU FEB 14 2013/ SHORT TERM...A DISORGANIZED WEAK TROUGH WILL SLIDE FROM THE NORTHERN ROCKIES ONTO THE PLAINS TODAY...BRINGING SOME WEAK LIFT AND COLD ADVECTION ACROSS NORTHEASTERN COLORADO. GFS SEEMS TO HAVE A BETTER HANDLE ON THE POSITION AND TIMING OF THE LIFT...NAM SEEMS TOO FAR SOUTH WITH THE BEST LIFT AT THIS TIME. BEST ENHANCEMENT ON SATELLITE UPSTREAM FROM DENVER ACTUALLY SEEMS TO HAVE VERY LITTLE PRECIPITATION WITH IT...THE BANDED SHOWERS ARE IN THE COLDER AIR FURTHER NORTH ACROSS WYOMING. EVEN THERE THE SHOWERS LOOK PRETTY LIGHT. CURRENT MOTION WOULD HAVE THESE CLIPPING NORTHEASTERN COLORADO THIS MORNING. HOWEVER...DEEPER COLD AIR WILL BE FORCED SOUTHWARD BEHIND THE TROUGH...EVIDENCED BY PRESSURE RISES IN MONTANA...AND THIS SHOULD HELP PULL THE SHOWER BANDS SOUTHWARD THIS AFTERNOON. IN ADDITION THE CONVERGENCE THAT DEVELOPS IN AND NEAR THE FOOTHILLS WILL LIKELY HELP FORCE SHOWERS SOMEWHERE IN THAT AREA...PROBABLY WITH SOME MOTION TO THE BANDING IN THE COLD ADVECTION. HARD TO SAY WHERE THE SYNOPTIC SCALE BANDS WILL GO...BUT FAVORING THIS AREA OF CONVERGENCE AS THE MODELS DO MAKES SENSE. AS A RESULT...EVEN THOUGH EXPECTED AMOUNTS WILL BE LIGHT THE CHANCE OF GETTING A LITTLE SNOW AROUND DENVER LOOKS FAIRLY GOOD FROM MID AFTERNOON INTO EARLY EVENING. EXPECT MOST PLACES WILL HAVE LESS THAN AN INCH...THOUGH IF A BAND STALLS OR SOMEPLACE GETS HIT MORE THAN ONCE HEAVIER SNOW WOULD BE POSSIBLE. WITH THE FOOTHILLS FAVORED FOR A WHILE THE IDEA OF 1 TO 3 INCHES SEEMS FINE. MAIN CHANGES IN THIS PACKAGE WILL BE TO FOCUS MORE CLEARLY ON THE AFTERNOON AND EVENING PERIODS...AND TO RAISE POPS IN THE HIGHER MOUNTAINS AS WELL AS THERE COULD BE REPEATED PERIODS OF LIGHT SNOW. LONG TERM...ANOTHER BATCH OF ENERGY MOVES DOWN THE BACK SIDE OF THE MEAN TROUGH EAST OF US ON FRIDAY. STRONG NORTHERLY FLOW ALOFT IS PROGGED OVER THE CWA BY FRIDAY AFTERNOON INTO THE EVENING. BY SATURDAY MORNING...THE FLOW ALOFT RELAXES AS AN UPPER RIDGE MOVES EASTWARD. THE UPPER RIDGE MOVES ACROSS THE FORECAST AREA SATURDAY NIGHT WITH FAIRLY WEAK ZONAL FLOW ALOFT. THE QG VERTICAL VELOCITY FIELDS HAVE A BIT OF UPWARD MOTION PROGGED FRIDAY MORNING FOR THE EASTERN THIRD OF THE CWA ONLY. IT`S ALL DOWNWARD MOTION FOR THE REST OF FRIDAY THROUGH SATURDAY. VERY WEAK UPWARD MOTION IS INDICATED FOR SATURDAY NIGHT. ON FRIDAY MORNING...THE BOUNDARY LAYER FLOW BECOMES NORTHWESTERLY AND THAT CONTINUES INTO FRIDAY EVENING...THEN THE FLOW IS WESTERLY THROUGH MUCH OF SATURDAY. ALL DOWNSLOPING. FOR MOISTURE...THERE IS QUITE A BIT OVER MUCH OF THE CWA FRIDAY...HOWEVER IS DOES GRADUALLY DECREASE THROUGH THE DAY. MODELS HAVE IT PRETTY DRY BY 12Z SATURDAY MORNING. SATURDAY AND SATURDAY EVENING ARE VERY DRY. THERE IS A BIT OF UPPER LEVEL MOISTURE PROGGED TO MOVE INTO THE WESTERN HALF OF THE CWA SATURDAY NIGHT LATE. THE QPF FIELDS HAVE A TAD OF MEASURABLE SNOWFALL OVER THE MOUNTAINS AND EASTERN HALF OF THE PLAINS FRIDAY. AFTER THAT THERE IS NOTHING THROUGH SUNDAY MORNING AT 12Z. WILL KEEP "LIKELY"S GOING IN THE MOUNTAINS FOR SOME OF FRIDAY WITH THE OROGRAPHICS AND MOISTURE IN MIND. WILL TAPER POPS OFF BY AFTERNOON AND END THEM IN THE MOUNTAINS DURING THE EVENING. WILL LOWER POPS TO NOTHING OR NEAR NOTHING OVER THE FOOTHILLS AND IMMEDIATE PLAINS WITH THE STRONG DOWNSLOPE DRYING IN MIND ON FRIDAY. WILL LEAVE SOME MINOR POPS OVER THE REST OF THE PLAINS FRIDAY. AFTER THAT DRY FOR ALL AREAS THROUGH 12Z SUNDAY MORNING. FOR TEMPERATURES...FRIDAY`S HIGHS WILL STAY CLOSE TO TODAY`S READINGS. SATURDAY`S HIGHS ARE SUPPOSED TO WARM SOME 6-12 C FROM FRIDAY`S READINGS. FOR THE LATER DAYS...SUNDAY THROUGH WEDNESDAY...MODELS HAVE WEAK ZONAL FLOW OVER THE CWA SUNDAY. AN UPPER TROUGH IS TO PUSH ACROSS COLORADO SUNDAY NIGHT INTO MONDAY MORNING. PRETTY STRONG NORTHWESTERLY FLOW ALOFT IS PROGGED MONDAY INTO MONDAY NIGHT...THEN ANOTHER UPPER RIDGE MOVES OVER THROUGH MID DAY TUESDAY. FOR THE REST OF TUESDAY INTO EARLY WEDNESDAY...PRETTY STRONG WEST-SOUTHWESTERLY FLOW ALOFT IS EXPECTED IN ADVANCE OF THE NEXT UPPER TROUGH. THIS ONE LOOKS FAIRLY STRONG...BUT WHO KNOWS? THE LAST SEVERAL SYSTEMS HAVE BEEN WEAK AND DISORGANIZED AND POOR PRECIPITATION-MAKERS...YET THEY GENERALLY LOOKED MUCH BETTER A FEW DAYS OUT. THE UPCOMING MONDAY TROUGH IS A GOOD EXAMPLE...BUT THERE IS STILL TIME BEFORE IT ARRIVES. SO BY 00Z LATE WEDNESDAY AFTERNOON...THE GFS SHOWS A PRETTY STRONG OPEN TROUGH AXIS OVER THE WESTERN COLORADO BORDER. AT THE SAME TIME...THE ECMWF HAS A CLOSED CIRCULATION AT THE BOTTOM OF ITS UPPER TROUGH OVER THE SOUTHWESTERN CORNER OF COLORADO. THE TWO MODELS ARE IN GOOD AGREEMENT TIMING-WISE. FOR MOISTURE...IT INCREASES UP HIGH ON SUNDAY...AND THERE IS SOME FOR EARLY MONDAY`S TROUGH...BUT NOTHING GREAT. YESTERDAY AND THE DAY BEFORE`S 00Z MODEL RUNS HAD UPSLOPE AND DEEP MOISTURE FOR THE PLAINS WITH THE EARLY MONDAY TROUGH...NOW THE ECMWF HAS LITTLE MOISTURE AND NO UPSLOPE. THE GFS HAS BRIEF SHOT. AGAIN...THEY ARE CHANGING FOR THE WORSE IF PRECIPITATION IS WHAT YOU SEEK. TEMPERATURES WARM SUNDAY...THEN COOL OFF MONDAY...THEN WARM AGAIN TUESDAY AND WEDNESDAY. AVIATION...A COLD FRONT IS EXPECTED THROUGH DENVER IN THE 16Z TO 18Z RANGE WITH LOWERING CEILINGS AND NORTH WINDS GUSTING IN THE 20 TO 30 KNOT RANGE. EXPECT INSTRUMENT APPROACHES WILL BE NEEDED TO KDEN BY 20Z...WITH PERIODS OF IFR CONDITIONS IN LIGHT SNOW SHOWERS BETWEEN 21Z AND 03Z. THERE IS STILL A CHANCE OF LIGHT SHOWERS AFTER THAT TIME...AND CEILINGS MAY REMAIN BELOW 7000 FT AGL THE REST OF THE NIGHT...BUT WILL LIKELY BE HIGHER BY FRIDAY MORNING. IF THERE IS SNOW ACCUMULATIONS ARE EXPECTED TO BE LESS THAN AN INCH. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....RJK AVIATION...D-L
AREA FORECAST DISCUSSION
NWS ALBANY NY
1009 PM EST FRI FEB 15 2013 .SYNOPSIS... TONIGHT THROUGH SATURDAY NIGHT...WAVES OF LOW PRESSURE WILL MOVE FROM THE MID ATLANTIC COAST TO WELL SOUTH AND EAST OF LONG ISLAND BRINGING A LIGHT SNOWFALL FROM THE MID HUDSON VALLEY INTO WESTERN NEW ENGLAND. THE WAVES OF LOW PRESSURE WILL MERGE INTO A POWERFUL STORM EAST OF THE GULF OF MAINE BRINGING BLUSTERY AND COLD CONDITIONS FOR SUNDAY...BUT WITH THE BULK OF SNOWFALL OCCURRING ACROSS COASTAL NEW ENGLAND. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 10 PM EST...PRECIPITATION IS BEGINNING TO BLOSSOM ON KENX RADAR...PARTICULARLY ACROSS THE MID HUDSON VALLEY REGION...AND ALSO ACROSS THE WEST/CENTRAL MOHAWK RIVER VALLEY AND AREAS JUST N AND W OF THE IMMEDIATE CAPITAL REGION. LATEST RUC13 INDICATES AN AREA OF ENHANCED 850-700 MB FRONTOGENETICAL FORCING ACROSS EASTERN PA EXTENDING INTO EASTERN NYS...AND THIS AREA IS EXPECTED TO CONTINUE EXPANDING NE OVER THE NEXT 1-3 HOURS...BEFORE GRADUALLY SHIFTING EASTWARD A FEW HOURS AFTER MIDNIGHT. BASED ON THIS...AND REGIONAL RADAR TRENDS...HAVE INCREASED POPS INTO THE CHC RANGE OVER THE NEXT FEW HOURS FOR THE IMMEDIATE CAPITAL REGION AND AREAS N AND W...INTO THE CENTRAL MOHAWK RIVER VALLEY AND THE SARATOGA REGION. MOST OF THIS PRECIP SHOULD FALL AS SNOW...ALTHOUGH CAN NOT RULE OUT A FEW RAINDROPS INITIALLY IN SOME LOWER ELEVATIONS GIVEN A RELATIVELY WARM BOUNDARY LAYER. A LIGHT COATING COULD OCCUR ON SOME COLDER SURFACES FROM THIS LIGHT SNOW. FOR AREAS MAINLY S AND E OF ALBANY...THE PRECIPITATION AREA SHOULD CONTINUE EXPANDING N AND E THROUGH AROUND 2 AM...BEFORE SHIFTING SLOWLY EAST. BOUNDARY LAYER TEMPS REMAIN SOMEWHAT MILD...AND SHOULD ALLOW FOR PRECIP TO BEGIN MAINLY AS LIGHT RAIN IN VALLEY AREAS...WITH A RAIN/SNOW MIX ACROSS HIGHER ELEVATIONS. HOWEVER...AFTER ABOUT 1-2 HOURS OF EVAPORATIONAL COOLING...EVEN VALLEY AREAS SHOULD TRANSITION TO SNOW AROUND OR JUST AFTER MIDNIGHT...WITH HIGHER ELEVATIONS CHANGING OVER MORE QUICKLY. STILL EXPECT SNOWFALL TOTALS OF AROUND AN INCH FOR HUDSON VALLEY LOCATIONS...WITH PERHAPS 1-3 INCHES FOR AREAS E OF THE HUDSON RIVER INTO NW CT...AND EASTERN DUTCHESS CO. FURTHER N AND W...STILL EXPECT MAINLY UNDER AN INCH...WITH PERHAPS 1-2 INCHES ACROSS PORTIONS OF THE SOUTHERN BERKSHIRES. AS FOR MIN TEMPS...GIVEN THE ABUNDANT CLOUD COVER OVERNIGHT...AND THE FACT THAT CURRENT TEMPS ARE RUNNING A BIT WARMER THAN PREVIOUS GUIDANCE SUGGESTED...HAVE RAISED MINS BY ABOUT 1-3 DEGREES IN MOST AREAS...WITH MID/UPPER 20S EXPECTED WITHIN THE HUDSON RIVER VALLEY FROM ALBANY SOUTH...AND TEENS TO LOWER/MID 20S ACROSS THE SOUTHERN ADIRONDACKS. ELSEWHERE...EXPECT MAINLY LOWER/MID 20S. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... ANOTHER WAVE OF LOW PRESSURE MERGES OFFSHORE NEW ENGLAND AND RAPID STRENGTHENING OF THE SYSTEM SHOULD OCCUR AS AN UPPER CUT OFF LOW INTERACTS WITH THE SYSTEM. CONSENSUS FROM GUIDANCE AND ENSEMBLES SUGGESTS THE STORM TRACKS TOO FAR EAST TO REALLY IMPACT OUR FORECAST AREA...WITH PERHAPS JUST SOME ADDITIONAL LIGHT ACCUMULATION FOR WESTERN NEW ENGLAND SATURDAY NIGHT AND EARLY SUNDAY MORNING. STILL THERE SHOULD BE ENOUGH CLOUD COVER AND LIGHT WINDS TO KEEP HIGH TEMPERATURES A LITTLE BELOW NORMAL...IN THE LOWER TO MID 30S...20S IN HIGHER TERRAIN. AS THE STORM RAPIDLY STRENGTHENS AND TRACKS INTO SOUTHEASTERN CANADA...THE MEAN UPPER TROUGH AXIS BUILDS EAST AND VERY COLD AIR SPILLS EAST INTO OUR REGION. THE TIGHT PRESSURE GRADIENT AROUND THE STRONG LOW PRESSURE SHOULD SUPPORT STRONG WINDS THROUGHOUT THE NORTHEASTERN U.S. MAKING FOR A NOTICEABLY COLD DAY SUNDAY. THERE COULD BE WIND CHILL ISSUES AND MAYBE BORDERING ON WIND ADVISORY WIND SPEEDS IN SOME AREAS. HIGHS SUNDAY IN THE LOWER TO MID 20S...SOME UPPER 20S SOUTHERN AREAS AND TEENS IN HIGHER TERRAIN. THE STORM IS PREDICTED TO BE SLOW TO EXIT...AND THE WINDS MAY DIMINISH ONLY GRADUALLY SUNDAY NIGHT INTO MONDAY. AGAIN...THERE MAY BE SOME WIND CHILL ISSUES IN SOME AREAS...ESPECIALLY SUNDAY NIGHT. LOWS SUNDAY NIGHT IN THE SINGLE NUMBERS TO LOWER TEENS...AROUND OR JUST BELOW ZERO IN COLDER AREAS. HIGHS MONDAY IN THE UPPER 20S TO LOWER 30S...LOWER 20S IN HIGHER TERRAIN. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... MONDAY NIGHT...A RIDGE OF HIGH PRESSURE WILL SLIDE EASTWARD ACROSS THE REGION...WHICH SHOULD BRING GENERALLY DRY CONDITIONS...WITH DECREASING WIND. SOME HIGH/MID LEVEL CLOUDS MAY INCREASE LATE AT NIGHT IN ADVANCE OF A SYSTEM APPROACHING FROM THE SOUTHWEST. EXPECT ANOTHER COLD NIGHT...WITH MINS FALLING INTO THE SINGLE DIGITS ACROSS NORTHERN AREAS...AND TEENS ELSEWHERE. TUE-TUE NT...MODELS CONTINUE PREVIOUS TRENDS OF A MORE PROGRESSIVE...AND FURTHER NORTH TRACK OF A SYSTEM DURING THIS TIME PERIOD. STRONG WARM ADVECTION IN ADVANCE OF THIS SYSTEM SHOULD STILL BRING A PERIOD OF PRECIPITATION TO THE REGION...MOST LIKELY TUE AFTERNOON AND NIGHT...ALTHOUGH IT COULD START AS EARLY AS TUE MORNING. FORECAST SOUNDINGS INDICATE MUCH OF THE REGION SHOULD BE COLD ENOUGH TO SUPPORT MAINLY SNOW...ALTHOUGH BOUNDARY LAYER TEMPS...AND SOME WARMING WITHIN THE 925-850 LAYER COULD ALLOW FOR SOME RAIN TO MIX IN...ESP FOR AREAS SOUTH OF INTERSTATE 90 TUE AFTERNOON. WILL INDICATE CHC POPS FOR THIS TIME PERIOD...WITH MAINLY SNOW FOR NORTHERN AREAS...AND A RAIN/SNOW MIX FOR CENTRAL AND SOUTHERN AREAS DEVELOPING BY TUE AFTERNOON...WITH PRECIPITATION CHANGING TO SNOW ALL AREAS FOR TUE NT. MODELS HAVE TRENDED TOWARD LESS OVERALL QPF...WITH THE 12Z/GEM REMAINING THE WETTER OUTLIER ALLOWING FOR MORE SECONDARY COASTAL DEVELOPMENT FOR TUE NT. ASSUMING THE 12Z/GFS/GEFS AND ECMWF PROVE CORRECT...IT APPEARS THAT THIS EVENT SHOULD MAINLY COMPRISE OF LIGHT TO PERHAPS MODERATE PRECIPITATION AMTS. WED-THU NT...AS THE REMNANT UPPER LEVEL TROUGH PASSES NORTH OF THE REGION WED AND WED EVENING...THE DEEP CYCLONIC FLOW WITHIN COLD AIR ADVECTION SHOULD PROMOTE SCATTERED SNOW SHOWERS ACROSS MUCH OF THE REGION...WITH THE MORE PERSISTENT SNOW SHOWERS ACROSS TRADITIONALLY FAVORED AREAS OF THE WESTERN ADIRONDACKS...MOHAWK VALLEY...AND POSSIBLY ACROSS THE SOUTHERN GREENS AND NORTHERN BERKSHIRES. THE SNOW SHOWERS SHOULD DIMINISH IN AREAL COVERAGE LATE WED INTO WED NT...FOLLOWED BY FAIR AND COLD CONDITIONS FOR THU INTO THU NT WITH BELOW NORMAL TEMPS. SO...FOR MAX TEMPS...EXPECT LOWER/MID 30S IN VALLEYS WED...WITH MAINLY 20S ACROSS HIGHER ELEVATIONS...WITH MAX TEMPS A FEW DEGREES COLDER FOR THU. FOR MINS...EXPECT MAINLY 20S ACROSS VALLEY REGIONS AND ADJACENT WESTERN NEW ENGLAND FOR WED AM GIVEN CLOUDS AND SOME WIND...THEN TEENS IN LOWER ELEVATIONS...AND SINGLE DIGITS ACROSS HIGHER ELEVATIONS FOR THU AM AND THU NT/FRI AM. FRI...PREVIOUS RUNS OF VARIOUS GLOBAL DETERMINISTIC MODELS AND ENSEMBLES HAVE INDICATED ANOTHER POTENTIAL STORM SYSTEM APPROACHING THE REGION SOMETIME LATE FRI INTO NEXT WEEKEND. SEVERAL 12Z/15 MODELS HAVE TRENDED WEAKER...AND FURTHER SOUTH WITH ANY POTENTIAL SYSTEM...GIVEN STRENGTHENING UPPER LEVEL RIDGING/BLOCKING ACROSS CENTRAL/EASTERN CANADA. STILL A GREAT DEAL OF UNCERTAINTY AT THIS TIME RANGE...SO HAVE MAINTAINED CHC POPS FOR FRI...WITH THERMAL PROFILES SUGGESTING ALL SNOW. EXPECT MAX TEMPS TO POTENTIALLY REACH 30-35 IN LOWER ELEVATIONS...AND 20S FOR HIGHER TERRAIN. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... AN UPPER LEVEL DISTURBANCE WILL PASS ACROSS SOUTHERN PORTIONS OF THE REGION LATER TONIGHT. THIS DISTURBANCE WILL BRING WIDESPREAD MID LEVEL CLOUDS OVERNIGHT...ALONG WITH A BRIEF PERIOD OF LIGHT SNOW AT KPOU AND KPSF AFTER MIDNIGHT...WHICH COULD INITIALLY BE MIXED WITH RAIN. KALB APPEARS TO BE ON THE NORTHWEST EDGE OF THE DEVELOPING PRECIPITATION SHIELD...AND WILL ONLY INDICATE VCSH FOR NOW UNLESS RADAR TRENDS INDICATE OTHERWISE LATER THIS EVENING. IN AREAS WHERE THE SNOW DEVELOPS...A PERIOD OF MVFR OR POSSIBLE IFR VSBYS AND CIGS WILL BE POSSIBLE BETWEEN 06Z-10Z/SAT. ELSEWHERE...MAINLY VFR CONDITIONS ARE EXPECTED THROUGH DAYBREAK. ON SATURDAY...AREAS OF MVFR CIGS COULD LINGER AT KPOU AND KPSF THROUGH AROUND 15Z. OTHERWISE...VFR CONDITIONS ARE EXPECTED. WINDS WILL BECOME MAINLY NORTHWEST OVERNIGHT AT GENERALLY LESS THAN 7 T. WINDS WILL BECOME NORTH TO NORTHWEST ON SATURDAY AT GENERALLY 5-10 KT...ALTHOUGH MAY BE A BIT STRONGER AT KALB AND KPSF...ESP FROM LATE MORNING INTO THE AFTERNOON HOURS. OUTLOOK... SAT NT-TUE NT...VFR. NO SIG WX. WED...VFR BECMG MVFR/IFR. -SN/-RA POSSIBLE IN AFTERNOON. && .HYDROLOGY... NO HYDROLOGY PROBLEMS ARE EXPECTED OVER THE NEXT FEW DAYS. SNOW MELT WILL CONTINUE TO BE GRADUAL THROUGH SATURDAY WITH ABOVE FREEZING TEMPERATURES DURING THE DAY...AND BELOW FREEZING AT NIGHT. TEMPERATURES WILL BECOME COLDER FOR THE 2ND HALF OF THE WEEKEND SLOWING...AND EVEN ENDING THE SNOWMELT. THE PREDOMINANT PTYPE TODAY INTO THE MID WEEK WILL BE SNOW. THE SYSTEMS DURING THAT TIME FRAME ARE EXPECTED TO ONLY PRODUCE LIGHT SNOW AMOUNTS. THEREFORE...NO IMPACTS ARE EXPECTED ON THE ALY HSA WATERWAYS. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...NAS NEAR TERM...KL/NAS SHORT TERM...NAS LONG TERM...KL AVIATION...KL HYDROLOGY...NAS
AREA FORECAST DISCUSSION
NWS NEW YORK NY
706 PM EST FRI FEB 15 2013 .SYNOPSIS... A COLD FRONT MOVES ACROSS THE REGION TONIGHT AND STALLS TO OUR EAST ON SATURDAY. A NOR`EASTER WILL DEVELOP SATURDAY NIGHT WELL SOUTHEAST OF MONTAUK AND TRACK TOWARDS THE CANADIAN MARITIMES WITH THE HEAVIEST PRECIPITATION REMAINING JUST EAST OF THE AREA. COLD CANADIAN HIGH PRESSURE GRADUALLY BUILDS IN FOR SUNDAY INTO MONDAY. A COLD FRONT TRACKS ACROSS THE REGION LATE TUESDAY FOLLOWED BY HIGH PRESSURE WEDNESDAY THROUGH THURSDAY. A COMPLEX FRONTAL SYSTEM WILL APPROACH ON FRIDAY. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... EARLY THIS EVENING...THE COLD FRONTAL BOUNDARY IS ALONG SOUTHEAST PA THROUGH SOUTHEAST NEW YORK WITH INCREASING CLOUDS MOVING INTO THE LOWER HUDSON VALLEY WHILE PRECIP IS MAINLY ACROSS SOUTHEAST PA. THE COLD FRONT WILL MOVE SLOWLY ACROSS THE REGION TONIGHT GENERALLY BETWEEN 3Z AND 8Z WITH WINDS TURNING MORE NORTHERLY BEHIND IT FROM WEST TO EAST. COLD AIR ADVECTION BEGINS THEREAFTER THE STRENGTHENING NORTHERLY FLOW. JUST SOME MINOR ADJUSTMENTS TO POPS...TEMPS...CLOUDS...AND DEWPOINTS OVER THE NEXT FEW HOURS. OVERALL..FORECAST IS ON TRACK. LIGHT PCPN OVER SOUTH CENTRAL PA EXPANDS RAPIDLY THIS EVENING WITH ONSET AROUND 10 PM OVER NE NJ INTO LOWER HUDSON VALLEY. LATEST HRRR THOUGH SUGGEST LIGHT PCPN COULD EVEN MOVE IN AN HOUR EARLIER INTO THE LOWER HUDSON VALLEY. WE`RE IN AN AREA OF COUPLED JET STREAKS THAT IS PROVIDING ENOUGH OMEGA FOR THE LIGHT PCPN. QPF IS LESS THAN A QUARTER INCH AND PERHAPS LESS THAN A TENTH. TEMPS WILL FALL INTO THE 20`S OVER THE INTERIOR WITH 30`S ALONG THE COAST. THUS...PCPN STARTS AS LIGHT RAIN ALONG THE COAST AND THEN MIXES WITH WET SNOW...LITTLE OR NO ACCUMULATION. INLAND...THE PCPN IS MAINLY LIGHT SNOW...THUS 1 TO LOCALLY 2 INCHES ARE FCST WITH THE MAIN ACCUMULATION OCCURRING ON THE SNOW PACK DUE TO MARGINAL TEMPS AT THE START OF THE PCPN. LIGHT PCPN AXIS SLOWLY SHIFTS EAST BY EARLY SATURDAY. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... FOCUS OF ATTENTION IS ON EXPLOSIVE CYCLOGENESIS FORCED BY THE 160+ KT SUB TROPICAL JET LEFT FRONT QUAD ON SATURDAY NIGHT. BASED ON EXTENSIVE ANALYSIS OF ENSEMBLE SYSTEMS AND COLLABORATION WITHIN THE NATIONAL WEATHER SERVICE INCLUDING 6 COASTAL WFO`S AND HPC WWD...CONFIDENCE IS INCREASING ON A NEAR MISS FOR SIGNIFICANT PCPN SATURDAY NIGHT IN OUR FCST AREA. HAVE SEEN 12Z ECMWF...15Z SREF...12Z GEFS AND 18Z NAM. THUS...GOING WITH A CHANCE FOR VERY LIGHT PCPN WHICH WOULD INCLUDE SPRINKLES AND FLURRIES DURING THE DAY ON SATURDAY WITH HIGH TEMPS CLOSE TO THE SLIGHT COOLER NAM MOS. AS THE NOR`EASTER SPINS UP WELL OFF THE MID ATLANTIC COAST SATURDAY EVENING...POPS INCREASE TO CATEGORICAL EAST WITH LOW CHANCE WEST. PCPN IS ALL SNOW. HAVE AMOUNTS OF 2-3" FAR EAST AND AROUND AN INCH FROM NEW HAVEN TO WESTERN SUFFOLK. ELSEWHERE IT`S JUST A DUSTING. EVEN THESE AMOUNTS COULD BE HIGH. WILL KEEP THE OUTLOOK FOR THE FAR EASTERN ZONE WITH LOW CHANCE FOR THE TRACK TO SHIFT BACK SLIGHTLY TO THE WEST. WINDS REALLY START TO INCREASE AFTER MIDNIGHT. && .LONG TERM /SUNDAY THROUGH FRIDAY/... MEDIUM RANGE MODEL GUIDANCE IS STILL IN GENERAL AGREEMENT THROUGH THE END OF THE WEEK. TO START...INTENSE LOW PRESSURE WILL BE MOVING UP TROUGH THE CANADIAN MARITIMES ON SUNDAY AS ITS PARENT CLOSED UPPER LOW TRAVERSES THE REGION ON SUNDAY...WITH COLD/BLUSTERY CONDITIONS. NW FLOW 20-30 MPH WITH GUSTS 35-45 MPH AND TEMPS ONLY RISING TO THE UPPER 20S AND LOWER 30S WILL RESULT IN WIND CHILLS IN THE TEENS DURING THE DAY ON SUNDAY. WINDS WILL STILL REMAIN QUITE BRISK IN TO SUNDAY NIGHT...SO AS TEMPS FALL INTO THE TEENS AND LOWER 20S SUNDAY NIGHT...WIND CHILLS OF OF ZERO TO 10 BELOW ARE LIKELY. TEMPS AND WIND CHILLS SHOULD RECOVER A LITTLE MON INTO MON NIGHT AS A NARROW HIGH PRESSURE RIDGE SLIDES ACROSS...WITH HIGHS MAINLY 30-35 AND LOWS MON NIGHT IN THE 20S. AN ACCOMPANYING UPPER RIDGE SHOULD SLIDE BY TUE MORNING...ALLOWING A FRONTAL SYSTEM TO IMPACT THE AREA FROM THE WEST TUE INTO TUE NIGHT. IF PCPN ARRIVES EARLY ENOUGH ON TUE...IT COULD BEGIN AS A BRIEF PD OF SNOW OR A RAIN/SNOW MIX ACROSS THE INTERIOR...OTHERWISE RAIN SHOULD BE THE PREDOMINANT P-TYPE DURING THE DAY. AFTER COLD FROPA TUE EVENING...PCPN COULD CHANGE BACK TO SNOW...ESPECIALLY OVER THE INTERIOR...AS COLDER AIR BEGINS TO FILTER BACK IN. THE FLOW ALOFT WILL BEGIN TO TRANSITION TO A MORE BLOCKY REGIME DURING MID TO LATE NEXT WEEK...WITH TEMPS GENERALLY NEAR AVG. FIRST...HIGH PRESSURE WILL SLIDE ACROSS WED INTO THU EVENING...THEN AS ONE LEG OF A DEVELOPING OMEGA OR REX BLOCK BECOMES ESTABLISHED OVER THE NRN PLAINS LATE IN THE WEEK...A SERIES OF SRN STREAM DISTURBANCES TRAVELING ALONG ITS SRN PERIPHERY WILL IMPACT THE AREA. THE FIRST OF THESE SHOULD BRING A LIGHT SNOWFALL EVENT FRI INTO FRI NIGHT...AS HIGH PRESSURE TO THE NE SUPPLIES COLD SFC AIR AND WESTERLY FLOW ALOFT PREVENTS MID LEVEL WARMING. THE ECMWF HAS BEEN CONSISTENTLY PREDICTING A MORE SIGNIFICANT SRN STREAM LOW BEYOND THE END OF THE FCST PERIOD THAT WILL NEED TO BE WATCHED...SO WINTER APPEARS FAR FROM BEING OVER. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... A COLD FRONT GRADUALLY WORKS EAST ACROSS THE REGION TONIGHT. LOW PRESSURE DEVELOPS WELL SE OF THE REGION SAT. LIGHT PRECIPITATION WILL OVERSPREAD WESTERN TERMINALS AFTER 03Z. THE PRECIP WILL GRADUALLY TRANSITION TO SNOW AFTER MIDNIGHT. IFR CONDS LIKELY AT KSWF/KHPN. ACROSS CITY TERMINALS MVFR CONDS LIKELY WITH A PERIOD OF IFR POSSIBLE IN SN AFTER MIDNIGHT. POTENTIAL FOR AROUND AN INCH AT KHPN AND KSWF...ELSEWHERE LITTLE OR NO SNOW ACCUMULATION ON RUNWAYS WITH TEMPERATURES JUST ABOVE FREEZING. RA/SN GRADUALLY SHIFTS EASTWARDS AFTER MIDNIGHT...BUT LIKELY WEAKENING AS IT DOES SO. CONDS GRADUALLY IMPROVE TO VFR SAT MORNING...THEN GENERALLY VFR WITH N WINDS AROUND 10 KT. MVFR OR LOWER CONDS IN LIGHT SNOW DEVELOPMENT POSSIBLE FOR EASTERN TERMINALS AFTER 21Z...MORES KGON. NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KEWR FCSTER COMMENTS: AMENDMENTS MAY BE NEEDED TO ADJUST TIMING OF IMPROVEMENT TO VFR SAT MORNING. KJFK FCSTER COMMENTS: AMENDMENTS MAY BE NEEDED TO ADJUST TIMING OF IMPROVEMENT TO VFR SAT MORNING. KLGA FCSTER COMMENTS: AMENDMENTS MAY BE NEEDED TO ADJUST TIMING OF IMPROVEMENT TO VFR SAT MORNING. KTEB FCSTER COMMENTS: AMENDMENTS MAY BE NEEDED TO ADJUST TIMING OF IMPROVEMENT TO VFR SAT MORNING. KHPN FCSTER COMMENTS: AMENDMENTS MAY BE NEEDED TO ADJUST TIMING OF IMPROVEMENT TO VFR SAT MORNING. KISP FCSTER COMMENTS: AMENDMENTS MAY BE NEEDED TO ADJUST TIMING OF IMPROVEMENT TO VFR SAT MORNING. MVFR OR LOWER CONDS POSSIBLE IN LIGHT SNOW AFTER 21Z. .OUTLOOK FOR 00Z SUNDAY THROUGH TUESDAY... .SAT NIGHT-SUN...MVFR POSSIBLE EAST OF NYC TERMINALS. OFFSHORE LOW DEVELOPMENT WILL NEED TO WATCHED FOR ADDITIONAL PCPN. STRONG NW FLOW WITH GUSTS OF 35 TO 40 KT POSSIBLE ON SUN. .MON...VFR. GUSTY NW FLOW 25 TO 30 KT. .TUE...PSBL MVFR OR LOWER WITH PCPN. GUSTY SW FLOW. .WED...VFR. GUSTY W FLOW. && .MARINE... SUB-SCA CONDITIONS PREVAIL ON ALL WATERS INTO SATURDAY. WINDS VEER NORTH BY LATE TONIGHT AND INCREASE ON SATURDAY. GALES WILL LIKELY DEVELOP...ESPECIALLY EAST...LATE SAT NIGHT AS LOW PRESSURE WELL SOUTHEAST OF MONTAUK RAPIDLY DEEPENS. THUS GALE WATCH HAS BEEN ISSUED. GALES LIKELY ON ALL WATERS ON SUNDAY IN THE WAKE OF INTENSE LOW PRESSURE DEPARTING INTO THE CANADIAN MARITIMES...LASTING INTO SUNDAY NIGHT-MON ON THE OCEAN AND THE EASTERN SOUND/BAYS. QUIET CONDS SHOULD RETURN BY LATE DAY MON OR MON EVENING AS WEAK HIGH PRESSURE SLIDES ACROSS. INCREASING SW FLOW AHEAD OF AN APPROACHING FRONTAL SYSTEM COULD BRING MARGINAL SCA CONDS TO THE OCEAN WATERS FROM LATE DAY TUE INTO TUE EVENING...CONTINUING IN W-NW POST-FRONTAL FLOW ON WED. && .HYDROLOGY... NO HYDROLOGIC IMPACT EXPECTED WITH LIGHT PCPN THOUGH SATURDAY NIGHT. QPF WITH FRONTAL SYSTEMS ON TUE /MOSTLY RAIN/ AND AGAIN ON FRI /SNOW/ SHOULD BE LIGHT AND NOT PRESENT ANY PROBLEMS. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...GALE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ANZ330-340-350-353. && $$ SYNOPSIS...TONGUE NEAR TERM...JM/TONGUE SHORT TERM...TONGUE LONG TERM...GOODMAN AVIATION...DW MARINE...GOODMAN/TONGUE HYDROLOGY...TONGUE
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
954 PM EST FRI FEB 15 2013 .SYNOPSIS... LOW PRESSURE ALONG A COLD FRONT FROM SOUTHEASTERN NEW YORK STATE TO SOUTHERN VIRGINIA WILL MOVE OFF THE COAST EARLY SATURDAY MORNING. A NEW LOW PRESSURE SYSTEM WILL FORM ALONG THIS FRONT EAST OF NORTH CAROLINA SATURDAY AFTERNOON...INTENSIFYING AS IT PASSES EAST OF CAPE COD ON SUNDAY AS A LARGE AND STRONG GALE. HIGH PRESSURE IS FORECAST TO FOLLOW FOR MONDAY INTO EARLY TUESDAY. THEN A COLD FRONT FROM THE GREAT LAKES SHOULD MOVE THROUGH THE NORTHEAST LATER ON TUESDAY. A LARGE HIGH PRESSURE SYSTEM FROM CENTRAL CANADA SHOULD THEN BEGIN SLOWLY BUILD INTO THE AREA LATER ON WEDNESDAY THROUGH THURSDAY. A WARM FRONT MAY LIFT NORTH TOWARD THE AREA EARLY FRIDAY. && .NEAR TERM /UNTIL 7 AM SATURDAY MORNING/... 950 PM: ISSUED SHORT FUSE WSW FOR HIGH TERRAIN NW SECTION OF OUR FA BASED ON THE THE 00Z/16 NAM VV AND QPF...LATEST HPC QPF...AND THE 01Z/16 RAP. PRETTY GOOD CONVERGENCE ON THE SFC BOUNDARY AND SOME FGEN IS GENERATING DECENT QPF. VSBYS IN SNOW ARE DECREASING TO A MILE AS OF 945 PM. I KNOW THIS AREA GETS LOTS OF SNOW IN A WINTER BUT TO GET A LITTLE BETTER VSBY FOR THE SLIPPERY TRAVEL...A SHORT FUSE WSW WAS ISSUED. WE ACCIDENTALLY RAN IT TIL 4AM SUNDAY BUT REWORKED THE HAZARD PRIOR TO POSTING THE WSW. MOST OF WHAT WILL ACCUMULATE SHOULD BE COMPLETE BY 4 AM. RAISED POPS A BIT FOR SATURDAY IN NJ/DE WHERE THE NAM IS STARTING TO ADD QPF AND DECENT VV. THIS SYSTEM STILL BEARS MONITORING FOR AN ADVY SITUATION IN DE AND COASTAL NJ SATURDAY AND SATURDAY EVENING. 850PM: IMPRESSIVE VV IN THE NEW 00Z NAM FOR THE FIRST 3-6 HRS NW EDGE OF THE FA. SHOULD RESULT IN A BRIEF BUT MDT TO HEAVY WET SNOW FOR 2-4 HRS FM VCNTY KRDG-KABE NWWD. WILL ADJUST FCST SLIGHTLY. WE WILL BE ISSUING SPS`S FOR VERY SLIPPERY TRAVEL IN THIS AREA SHORTLY. TONIGHT...745 PM ESTF UPDATE 1.75 HRS EARLY. HAVE FURTHER DELAYED THE CHANGE TO SNOW ABOUT AN HOUR OR TWO AND THE ONSET OF PCPN AS WELL. THE RAP IS DOING PRETTY WELL. CLOUD TOP COOLING AND BRIGHT BANDING IS SHOWING THE SNOW COOLING BUT THE BL IS TOO WARM AND I DONT THINK AMOUNTS ARE GOING TO REACH FCST VALUES EXCEPT HIGH TERRAIN AND MAINLY N OF RTE 80. RAIN MAY BE SOMEWHAT CONVECTIVE IN NATURE. STRONG VV IN THE IDEAL DENDRITIC GROWTH ZONE MAY ASSIST SNOW AMTS FROM THE POCONOS INTO SUSSEX COUNTY WITH A PERIOD OF MDT SNOW THERE BETWEEN 4Z AND AND 7Z. POSSIBLY BRIEFLY DOWN TO ALLENTOWN AROUND 05Z-06Z? ALREADY TRIMMED SNOW AMTS PRIOR TO 06Z AND EVEN THESE ARE PROBABLY TOO LARGE BY 1/2 INCH. TEMPS WERE WARMED FURTHER THIS EVENING I95 NWWD. A CHANGEOVER TO SNOW SHOULD ARRIVE IN THE LEHIGH VALLEY AREA BETWEEN 04Z-06Z AND ABOUT 07Z PHL...IF ITS STILL PRECIPITATING. ANY SIGNIFICANT PRECIPITATION LIKELY SHUTS OFF FROM THE IMPULSE BEFORE DAYBREAK ALTHOUGH THERE IS MODEL DISCREPANCY ON THIS. CONFIDENCE ON SNOW AMOUNTS TONIGHT IS WELL BELOW AVERAGE. THATS WHY I HAVENT PUBLISHED A SNOW TOTAL MAP AND JUST LETTING THE CRON POST AMTS IN THE DAY 1 AND 2 SECTION OF OUR WINTER WX IMAGERY. && .SHORT TERM /7 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... THE FIRST IMPULSE SHOULD CLEAR US EARLY IN THE SHORT TERM. THEN, IF ONE WANTS A SNOWIER FORECAST, ONE FALLS INTO THE CANADIAN/GFS CAMP. OUR FORECAST THROUGH THE SHORT TERM LEANS AWAY FROM THIS AND TOWARD A ECMWF/NAM KIND OF SOLUTION, ALTHOUGH WE DO INCORPORATE SOME OF THE FORMER BECAUSE OF THE UNCERTAINTY. THE GFS AND CANADIAN ARE DEVELOPING MORE OF A NEGATIVE TILT WITH A STRONGER SECOND IMPULSE AT H5, AND THAT HAS THEM DEEPER AND FURTHER EAST WITH THE ASSOCIATED LOW PRESSURE SYSTEM (THE MAIN ONE WITH THIS MAJOR TROUGH AXIS). ALTHOUGH OUR QPF IS ON THE LIGHTER SIDE BECAUSE WE FAVOR A LESS VIGOROUS SOLUTION AT OUR LATITUDE, ALL MODEL SOUNDINGS SAY THAT ALL AREAS WOULD SEE SNOW EITHER FROM THE START OF OR ONLY A FEW HOURS INTO THE SHORT TERM. WE HAVE THEREFORE ADJUSTED MAX TEMPERATURES DOWNWARD. OUR QPF AND SNOW VALUES IN THE LATTER PART OF THE SHORT TERM AND THE FIRST PART OF THE LONG TERM COMBINED WOULD BRING OUR EASTERN ZONES INTO ADVISORY TERRITORY. GIVEN THE UNCERTAINTY, WE HAVE DECIDED NOT TO ISSUE ONE AT THIS TIME. WE DO NOTE THAT IF OUR FORECAST WERE CORRECT FROM THE NEAR TERM THROUGH THE EARLY PART OF THE LONG TERM, THEN WE WOULD SEE LOWER END ADVISORY SNOW AMOUNTS OVER A FAIR AMOUNT OF THE FORECAST AREA. HOWEVER, THIS WOULD HAPPEN OVER A PERIOD OF AT LEAST 24 HOURS, SOME OF WHICH WOULD BE FREE OF SIGNIFICANT PRECIPITATION. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... MODELS CONTINUE TO DIFFER ON HOW MUCH SNOW MIGHT FALL LATER SATURDAY AND SATURDAY NIGHT. THE LATEST RUN OF THE GFS INDICATES A SLIGHTLY MORE WESTERN TRACK WHILE THE LATEST ECMWF INDICATES A MORE EASTERLY TRACK. AS A RESULT...NO DRASTIC CHANGE HAS BEEN MADE TO THE FORECAST AT THIS POINT IN TIME. BASICALLY AN ADVISORY TO SUB-ADVISORY EVENT FOR THE CWA, WITH THE HIGHEST AMOUNTS CLOSEST TO THE COASTAL AREAS...WITH LESSER AMOUNTS FURTHER INLAND. WHATEVER SNOW DOES FALL, THE BULK OF IT SHOULD BE OVER BY 6 AM SUNDAY. SLIGHT POPS WERE ADDED TO THE WEATHER GRIDS FOR SUNDAY DUE TO THE PROXIMITY OF THE MID-LEVEL TROUGH, BUT NOTHING SIGNIFICANT IS EXPECTED DURING THIS TIME PERIOD. A BLUSTERY DAY IS EXPECTED IN THE CWA ON SUNDAY DUE TO THE PRESSURE GRADIENT FROM THE EXITING STORM. WITH HIGH TEMPERATURES IN THE MID 20S IN THE NORTH AND LOW TO MID 30S SOUTH...IT WILL FEEL LIKE WINTER AGAIN. WHETHER OR NOT WIND ADVISORIES WILL BE NECESSARY WILL DEPEND ON HOW FAR EAST THE STORM TRACK HAPPENS TO BE. MONDAY SHOULD BE A LESS WINDIER DAY WITH SUNNY SKIES. TEMPERATURES THOUGH SHOULD STILL BE ABOUT 5 TO 10 DEGREES COLDER THAN AVERAGE. AS THE HIGH SLIDES OFF THE COAST EARLY TUESDAY...A WARM FRONT WILL LIFT NORTH ALLOWING TEMPERATURES TO RISE INTO THE MID TO UPPER 40S IN MOST PLACES. PRECIPITATION COULD START OUT AS SNOW...BUT SHOULD CHANGE OVER TO RAIN AS THE DAY WEAR ON. A COLD FRONT ASSOCIATED WITH A LOW PRESSURE SYSTEM MOVING THROUGH THE GREAT LAKES REGION WILL PASS THROUGH THE CWA TUESDAY EVENING/NIGHT...WHICH WILL BRING BACK COLDER TEMPERATURES AND CHANGE ANY LINGERING RAIN TO SNOW...ESPECIALLY IN THE NORTH. THEN BASICALLY BENIGN WEATHER UNTIL THE NEXT SYSTEM APPROACHES FROM THE WEST ON FRIDAY. PRECIP WITH THAT EVENT LOOKS LIKE IT WILL BE MAINLY RAIN IN THE SOUTH WITH A LEAST A MIXTURE IN THE NORTH. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TONIGHT...CONDITIONS ARE FORECAST TO DETERIORATE TO MVFR OR IFR OVER ALL THE TAF SITES FROM NORTHWEST TO SOUTHEAST. THERE MAY BE A PERIOD WHEN THEY IMPROVE TO MVFR OR VFR ON SATURDAY MORNING BEFORE THEY MAY BEGIN TO DETERIORATE LATER IN THE DAY. WINDS SHOULD VEER FROM SOUTHWEST OR WEST TO NORTH DURING THE COURSE OF THE TAF PERIOD WITH SOME GUSTINESS TO AROUND 20 KT EARLY IN THE PERIOD AND PERHAPS AGAIN LATE. OUTLOOK... SATURDAY NIGHT...IFR CONDITIONS...ESPECIALLY SOUTH AND EAST OF I-95...IMPROVING TO VFR TOWARD MORNING. SUNDAY...MAINLY VFR AND BLUSTERY. POSSIBLE MVFR SNOW SHWRS NORTH. NORTHWEST WINDS GUSTING 25 TO 30 KNOTS. CONFIDENCE MODERATE. MONDAY AND MONDAY NIGHT...MAINLY VFR. CONFIDENCE HIGH. TUESDAY...LOWERING TO MVFR OR IFR IN MIXED PRECIPITATION IN THE MORNING. CHANCE OF LLWS. CONFIDENCE IS MODERATE. TUESDAY NIGHT...IMPROVING TO VFR. WEDNESDAY...MAINLY VFR. && .MARINE... SUB-ADVISORY CONDITIONS ARE FORECAST INTO SATURDAY, BUT THEN WILL APPROACH OR REACH ADVISORY CONDITIONS LATE IN THE DAY ON GOOD COLD AIR ADVECTION AND A NORTHWEST FLOW. SEAS SHOULD BUILD TO ADVISORY CONDITIONS BY LATE SATURDAY AFTERNOON. OUTLOOK... THE DEVELOPING AND DEEPENING OFFSHORE LOW OFF NORTH CAROLINA WILL CONTINUE SCA CONDITIONS OVER MARINE AREA (OCEAN AND DELAWARE BAY) WIDESPREAD SCA CONDITIONS THROUGH THE REMAIN PORTION OF THE WEEKEND. DEPENDING ON THE PATH OF THIS STORM...GALES ARE EVEN POSSIBLE SATURDAY NIGHT INTO SUNDAY ON THE OCEAN AND LOWER DELAWARE BAY. THIS SITUATION WILL BE RE- EXAMINED WITH LATER MODEL RUNS. A SOUTHWEST FLOW BEHIND AN ADVANCING WARM FRONT IS EXPECTED TO SCA BACK TO THE FORECAST WATERS ON TUESDAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...WINTER WEATHER ADVISORY UNTIL 5 AM EST SATURDAY FOR PAZ055. NJ...WINTER WEATHER ADVISORY UNTIL 5 AM EST SATURDAY FOR NJZ001-007- 008. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...DRAG/MIKETTA NEAR TERM...DRAG 954P SHORT TERM...DELISI LONG TERM...MIKETTA AVIATION...DELISI/DRAG/MIKETTA MARINE...DELISI/DRAG/MIKETTA EQUIPMENT...
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
850 PM EST FRI FEB 15 2013 .SYNOPSIS... LOW PRESSURE ALONG A COLD FRONT FROM SOUTHEASTERN NEW YORK STATE TO SOUTHERN VIRGINIA WILL MOVE OFF THE COAST EARLY SATURDAY MORNING. A NEW LOW PRESSURE SYSTEM WILL FORM ALONG THIS FRONT EAST OF NORTH CAROLINA SATURDAY AFTERNOON...INTENSIFYING AS IT PASSES EAST OF CAPE COD ON SUNDAY AS A LARGE AND STRONG GALE. HIGH PRESSURE IS FORECAST TO FOLLOW FOR MONDAY INTO EARLY TUESDAY. THEN A COLD FRONT FROM THE GREAT LAKES SHOULD MOVE THROUGH THE NORTHEAST LATER ON TUESDAY. A LARGE HIGH PRESSURE SYSTEM FROM CENTRAL CANADA SHOULD THEN BEGIN SLOWLY BUILD INTO THE AREA LATER ON WEDNESDAY THROUGH THURSDAY. A WARM FRONT MAY LIFT NORTH TOWARD THE AREA EARLY FRIDAY. && .NEAR TERM /UNTIL 7 AM SATURDAY MORNING/... 850PM: IMPRESSIVE VV IN THE NEW 00Z NAM FOR THE FIRST 3-6 HRS NW EDGE OF THE FA. SHOULD RESULT IN A BRIEF BUT MDT TO HEAVY WET SNOW FOR 2-4 HRS FM VCNTY KRDG-KABE NWWD. WILL ADJUST FCST SLIGHTLY. WE WILL BE ISSUING SPS`S FOR VERY SLIPPERY TRAVEL IN THIS AREA SHORTLY. TONIGHT...745 PM ESTF UPDATE 1.75 HRS EARLY. HAVE FURTHER DELAYED THE CHANGE TO SNOW ABOUT AN HOUR OR TWO AND THE ONSET OF PCPN AS WELL. THE RAP IS DOING PRETTY WELL. CLOUD TOP COOLING AND BRIGHT BANDING IS SHOWING THE SNOW COOLING BUT THE BL IS TOO WARM AND I DONT THINK AMOUNTS ARE GOING TO REACH FCST VALUES EXCEPT HIGH TERRAIN AND MAINLY N OF RTE 80. RAIN MAY BE SOMEWHAT CONVECTIVE IN NATURE. STRONG VV IN THE IDEAL DENDRITIC GROWTH ZONE MAY ASSIST SNOW AMTS FROM THE POCONOS INTO SUSSEX COUNTY WITH A PERIOD OF MDT SNOW THERE BETWEEN 4Z AND AND 7Z. POSSIBLY BRIEFLY DOWN TO ALLENTOWN AROUND 05Z-06Z? ALREADY TRIMMED SNOW AMTS PRIOR TO 06Z AND EVEN THESE ARE PROBABLY TOO LARGE BY 1/2 INCH. TEMPS WERE WARMED FURTHER THIS EVENING I95 NWWD. A CHANGEOVER TO SNOW SHOULD ARRIVE IN THE LEHIGH VALLEY AREA BETWEEN 04Z-06Z AND ABOUT 07Z PHL...IF ITS STILL PRECIPITATING. ANY SIGNIFICANT PRECIPITATION LIKELY SHUTS OFF FROM THE IMPULSE BEFORE DAYBREAK ALTHOUGH THERE IS MODEL DISCREPANCY ON THIS. CONFIDENCE ON SNOW AMOUNTS TONIGHT IS WELL BELOW AVERAGE. THATS WHY I HAVENT PUBLISHED A SNOW TOTAL MAP AND JUST LETTING THE CRON POST AMTS IN THE DAY 1 AND 2 SECTION OF OUR WINTER WX IMAGERY. && .SHORT TERM /7 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... THE FIRST IMPULSE SHOULD CLEAR US EARLY IN THE SHORT TERM. THEN, IF ONE WANTS A SNOWIER FORECAST, ONE FALLS INTO THE CANADIAN/GFS CAMP. OUR FORECAST THROUGH THE SHORT TERM LEANS AWAY FROM THIS AND TOWARD A ECMWF/NAM KIND OF SOLUTION, ALTHOUGH WE DO INCORPORATE SOME OF THE FORMER BECAUSE OF THE UNCERTAINTY. THE GFS AND CANADIAN ARE DEVELOPING MORE OF A NEGATIVE TILT WITH A STRONGER SECOND IMPULSE AT H5, AND THAT HAS THEM DEEPER AND FURTHER EAST WITH THE ASSOCIATED LOW PRESSURE SYSTEM (THE MAIN ONE WITH THIS MAJOR TROUGH AXIS). ALTHOUGH OUR QPF IS ON THE LIGHTER SIDE BECAUSE WE FAVOR A LESS VIGOROUS SOLUTION AT OUR LATITUDE, ALL MODEL SOUNDINGS SAY THAT ALL AREAS WOULD SEE SNOW EITHER FROM THE START OF OR ONLY A FEW HOURS INTO THE SHORT TERM. WE HAVE THEREFORE ADJUSTED MAX TEMPERATURES DOWNWARD. OUR QPF AND SNOW VALUES IN THE LATTER PART OF THE SHORT TERM AND THE FIRST PART OF THE LONG TERM COMBINED WOULD BRING OUR EASTERN ZONES INTO ADVISORY TERRITORY. GIVEN THE UNCERTAINTY, WE HAVE DECIDED NOT TO ISSUE ONE AT THIS TIME. WE DO NOTE THAT IF OUR FORECAST WERE CORRECT FROM THE NEAR TERM THROUGH THE EARLY PART OF THE LONG TERM, THEN WE WOULD SEE LOWER END ADVISORY SNOW AMOUNTS OVER A FAIR AMOUNT OF THE FORECAST AREA. HOWEVER, THIS WOULD HAPPEN OVER A PERIOD OF AT LEAST 24 HOURS, SOME OF WHICH WOULD BE FREE OF SIGNIFICANT PRECIPITATION. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... MODELS CONTINUE TO DIFFER ON HOW MUCH SNOW MIGHT FALL LATER SATURDAY AND SATURDAY NIGHT. THE LATEST RUN OF THE GFS INDICATES A SLIGHTLY MORE WESTERN TRACK WHILE THE LATEST ECMWF INDICATES A MORE EASTERLY TRACK. AS A RESULT...NO DRASTIC CHANGE HAS BEEN MADE TO THE FORECAST AT THIS POINT IN TIME. BASICALLY AN ADVISORY TO SUB-ADVISORY EVENT FOR THE CWA, WITH THE HIGHEST AMOUNTS CLOSEST TO THE COASTAL AREAS...WITH LESSER AMOUNTS FURTHER INLAND. WHATEVER SNOW DOES FALL, THE BULK OF IT SHOULD BE OVER BY 6 AM SUNDAY. SLIGHT POPS WERE ADDED TO THE WEATHER GRIDS FOR SUNDAY DUE TO THE PROXIMITY OF THE MID-LEVEL TROUGH, BUT NOTHING SIGNIFICANT IS EXPECTED DURING THIS TIME PERIOD. A BLUSTERY DAY IS EXPECTED IN THE CWA ON SUNDAY DUE TO THE PRESSURE GRADIENT FROM THE EXITING STORM. WITH HIGH TEMPERATURES IN THE MID 20S IN THE NORTH AND LOW TO MID 30S SOUTH...IT WILL FEEL LIKE WINTER AGAIN. WHETHER OR NOT WIND ADVISORIES WILL BE NECESSARY WILL DEPEND ON HOW FAR EAST THE STORM TRACK HAPPENS TO BE. MONDAY SHOULD BE A LESS WINDIER DAY WITH SUNNY SKIES. TEMPERATURES THOUGH SHOULD STILL BE ABOUT 5 TO 10 DEGREES COLDER THAN AVERAGE. AS THE HIGH SLIDES OFF THE COAST EARLY TUESDAY...A WARM FRONT WILL LIFT NORTH ALLOWING TEMPERATURES TO RISE INTO THE MID TO UPPER 40S IN MOST PLACES. PRECIPITATION COULD START OUT AS SNOW...BUT SHOULD CHANGE OVER TO RAIN AS THE DAY WEAR ON. A COLD FRONT ASSOCIATED WITH A LOW PRESSURE SYSTEM MOVING THROUGH THE GREAT LAKES REGION WILL PASS THROUGH THE CWA TUESDAY EVENING/NIGHT...WHICH WILL BRING BACK COLDER TEMPERATURES AND CHANGE ANY LINGERING RAIN TO SNOW...ESPECIALLY IN THE NORTH. THEN BASICALLY BENIGN WEATHER UNTIL THE NEXT SYSTEM APPROACHES FROM THE WEST ON FRIDAY. PRECIP WITH THAT EVENT LOOKS LIKE IT WILL BE MAINLY RAIN IN THE SOUTH WITH A LEAST A MIXTURE IN THE NORTH. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TONIGHT...CONDITIONS ARE FORECAST TO DETERIORATE TO MVFR OR IFR OVER ALL THE TAF SITES FROM NORTHWEST TO SOUTHEAST. THERE MAY BE A PERIOD WHEN THEY IMPROVE TO MVFR OR VFR ON SATURDAY MORNING BEFORE THEY MAY BEGIN TO DETERIORATE LATER IN THE DAY. WINDS SHOULD VEER FROM SOUTHWEST OR WEST TO NORTH DURING THE COURSE OF THE TAF PERIOD WITH SOME GUSTINESS TO AROUND 20 KT EARLY IN THE PERIOD AND PERHAPS AGAIN LATE. OUTLOOK... SATURDAY NIGHT...IFR CONDITIONS...ESPECIALLY SOUTH AND EAST OF I-95...IMPROVING TO VFR TOWARD MORNING. SUNDAY...MAINLY VFR AND BLUSTERY. POSSIBLE MVFR SNOW SHWRS NORTH. NORTHWEST WINDS GUSTING 25 TO 30 KNOTS. CONFIDENCE MODERATE. MONDAY AND MONDAY NIGHT...MAINLY VFR. CONFIDENCE HIGH. TUESDAY...LOWERING TO MVFR OR IFR IN MIXED PRECIPITATION IN THE MORNING. CHANCE OF LLWS. CONFIDENCE IS MODERATE. TUESDAY NIGHT...IMPROVING TO VFR. WEDNESDAY...MAINLY VFR. && .MARINE... SUB-ADVISORY CONDITIONS ARE FORECAST INTO SATURDAY, BUT THEN WILL APPROACH OR REACH ADVISORY CONDITIONS LATE IN THE DAY ON GOOD COLD AIR ADVECTION AND A NORTHWEST FLOW. SEAS SHOULD BUILD TO ADVISORY CONDITIONS BY LATE SATURDAY AFTERNOON. OUTLOOK... THE DEVELOPING AND DEEPENING OFFSHORE LOW OFF NORTH CAROLINA WILL CONTINUE SCA CONDITIONS OVER MARINE AREA (OCEAN AND DELAWARE BAY) WIDESPREAD SCA CONDITIONS THROUGH THE REMAIN PORTION OF THE WEEKEND. DEPENDING ON THE PATH OF THIS STORM...GALES ARE EVEN POSSIBLE SATURDAY NIGHT INTO SUNDAY ON THE OCEAN AND LOWER DELAWARE BAY. THIS SITUATION WILL BE RE- EXAMINED WITH LATER MODEL RUNS. A SOUTHWEST FLOW BEHIND AN ADVANCING WARM FRONT IS EXPECTED TO SCA BACK TO THE FORECAST WATERS ON TUESDAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...DRAG/MIKETTA NEAR TERM...DRAG 850P SHORT TERM...DELISI LONG TERM...MIKETTA AVIATION...DELISI/DRAG/MIKETTA MARINE...DELISI/DRAG/MIKETTA EQUIPMENT...
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
819 PM EST FRI FEB 15 2013 .SYNOPSIS... LOW PRESSURE ALONG A COLD FRONT FROM SOUTHEASTERN NEW YORK STATE TO SOUTHERN VIRGINIA WILL MOVE OFF THE COAST EARLY SATURDAY MORNING. A NEW LOW PRESSURE SYSTEM WILL FORM ALONG THIS FRONT EAST OF NORTH CAROLINA SATURDAY AFTERNOON...INTENSIFYING AS IT PASSES EAST OF CAPE COD ON SUNDAY AS A LARGE AND STRONG GALE. HIGH PRESSURE IS FORECAST TO FOLLOW FOR MONDAY INTO EARLY TUESDAY. THEN A COLD FRONT FROM THE GREAT LAKES SHOULD MOVE THROUGH THE NORTHEAST LATER ON TUESDAY. A LARGE HIGH PRESSURE SYSTEM FROM CENTRAL CANADA SHOULD THEN BEGIN SLOWLY BUILD INTO THE AREA LATER ON WEDNESDAY THROUGH THURSDAY. A WARM FRONT MAY LIFT NORTH TOWARD THE AREA EARLY FRIDAY. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... TONIGHT...745 PM ESTF UPDATE 1.75 HRS EARLY. HAVE FURTHER DELAYED THE CHANGE TO SNOW ABOUT AN HOUR OR TWO AND THE ONSET OF PCPN AS WELL. THE RAP IS DOING PRETTY WELL. CLOUD TOP COOLING AND BRIGHT BANDING IS SHOWING THE SNOW COOLING BUT THE BL IS TOO WARM AND I DONT THINK AMOUNTS ARE GOING TO REACH FCST VALUES EXCEPT HIGH TERRAIN AND MAINLY N OF RTE 80. RAIN MAY BE SOMEWHAT CONVECTIVE IN NATURE. STRONG VV IN THE IDEAL DENDRITIC GROWTH ZONE MAY ASSIST SNOW AMTS FROM THE POCONOS INTO SUSSEX COUNTY WITH A PERIOD OF MDT SNOW THERE BETWEEN 4Z AND AND 7Z. POSSIBLY BRIEFLY DOWN TO ALLENTOWN AROUND 05Z-06Z? ALREADY TRIMMED SNOW AMTS PRIOR TO 06Z AND EVEN THESE ARE PROBABLY TOO LARGE BY 1/2 INCH. TEMPS WERE WARMED FURTHER THIS EVENING I95 NWWD. A CHANGEOVER TO SNOW SHOULD ARRIVE IN THE LEHIGH VALLEY AREA BETWEEN 04Z-06Z AND ABOUT 07Z PHL...IF ITS STILL PRECIPITATING. ANY SIGNIFICANT PRECIPITATION LIKELY SHUTS OFF FROM THE IMPULSE BEFORE DAYBREAK ALTHOUGH THERE IS MODEL DISCREPANCY ON THIS. CONFIDENCE ON SNOW AMOUNTS TONIGHT IS WELL BELOW AVERAGE. THATS WHY I HAVENT PUBLISHED A SNOW TOTAL MAP AND JUST LETTING THE CRON POST AMTS IN THE DAY 1 AND 2 SECTION OF OUR WINTER WX IMAGERY. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... THE FIRST IMPULSE SHOULD CLEAR US EARLY IN THE SHORT TERM. THEN, IF ONE WANTS A SNOWIER FORECAST, ONE FALLS INTO THE CANADIAN/GFS CAMP. OUR FORECAST THROUGH THE SHORT TERM LEANS AWAY FROM THIS AND TOWARD A ECMWF/NAM KIND OF SOLUTION, ALTHOUGH WE DO INCORPORATE SOME OF THE FORMER BECAUSE OF THE UNCERTAINTY. THE GFS AND CANADIAN ARE DEVELOPING MORE OF A NEGATIVE TILT WITH A STRONGER SECOND IMPULSE AT H5, AND THAT HAS THEM DEEPER AND FURTHER EAST WITH THE ASSOCIATED LOW PRESSURE SYSTEM (THE MAIN ONE WITH THIS MAJOR TROUGH AXIS). ALTHOUGH OUR QPF IS ON THE LIGHTER SIDE BECAUSE WE FAVOR A LESS VIGOROUS SOLUTION AT OUR LATITUDE, ALL MODEL SOUNDINGS SAY THAT ALL AREAS WOULD SEE SNOW EITHER FROM THE START OF OR ONLY A FEW HOURS INTO THE SHORT TERM. WE HAVE THEREFORE ADJUSTED MAX TEMPERATURES DOWNWARD. OUR QPF AND SNOW VALUES IN THE LATTER PART OF THE SHORT TERM AND THE FIRST PART OF THE LONG TERM COMBINED WOULD BRING OUR EASTERN ZONES INTO ADVISORY TERRITORY. GIVEN THE UNCERTAINTY, WE HAVE DECIDED NOT TO ISSUE ONE AT THIS TIME. WE DO NOTE THAT IF OUR FORECAST WERE CORRECT FROM THE NEAR TERM THROUGH THE EARLY PART OF THE LONG TERM, THEN WE WOULD SEE LOWER END ADVISORY SNOW AMOUNTS OVER A FAIR AMOUNT OF THE FORECAST AREA. HOWEVER, THIS WOULD HAPPEN OVER A PERIOD OF AT LEAST 24 HOURS, SOME OF WHICH WOULD BE FREE OF SIGNIFICANT PRECIPITATION. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... MODELS CONTINUE TO DIFFER ON HOW MUCH SNOW MIGHT FALL LATER SATURDAY AND SATURDAY NIGHT. THE LATEST RUN OF THE GFS INDICATES A SLIGHTLY MORE WESTERN TRACK WHILE THE LATEST ECMWF INDICATES A MORE EASTERLY TRACK. AS A RESULT...NO DRASTIC CHANGE HAS BEEN MADE TO THE FORECAST AT THIS POINT IN TIME. BASICALLY AN ADVISORY TO SUB-ADVISORY EVENT FOR THE CWA, WITH THE HIGHEST AMOUNTS CLOSEST TO THE COASTAL AREAS...WITH LESSER AMOUNTS FURTHER INLAND. WHATEVER SNOW DOES FALL, THE BULK OF IT SHOULD BE OVER BY 6 AM SUNDAY. SLIGHT POPS WERE ADDED TO THE WEATHER GRIDS FOR SUNDAY DUE TO THE PROXIMITY OF THE MID-LEVEL TROUGH, BUT NOTHING SIGNIFICANT IS EXPECTED DURING THIS TIME PERIOD. A BLUSTERY DAY IS EXPECTED IN THE CWA ON SUNDAY DUE TO THE PRESSURE GRADIENT FROM THE EXITING STORM. WITH HIGH TEMPERATURES IN THE MID 20S IN THE NORTH AND LOW TO MID 30S SOUTH...IT WILL FEEL LIKE WINTER AGAIN. WHETHER OR NOT WIND ADVISORIES WILL BE NECESSARY WILL DEPEND ON HOW FAR EAST THE STORM TRACK HAPPENS TO BE. MONDAY SHOULD BE A LESS WINDIER DAY WITH SUNNY SKIES. TEMPERATURES THOUGH SHOULD STILL BE ABOUT 5 TO 10 DEGREES COLDER THAN AVERAGE. AS THE HIGH SLIDES OFF THE COAST EARLY TUESDAY...A WARM FRONT WILL LIFT NORTH ALLOWING TEMPERATURES TO RISE INTO THE MID TO UPPER 40S IN MOST PLACES. PRECIPITATION COULD START OUT AS SNOW...BUT SHOULD CHANGE OVER TO RAIN AS THE DAY WEAR ON. A COLD FRONT ASSOCIATED WITH A LOW PRESSURE SYSTEM MOVING THROUGH THE GREAT LAKES REGION WILL PASS THROUGH THE CWA TUESDAY EVENING/NIGHT...WHICH WILL BRING BACK COLDER TEMPERATURES AND CHANGE ANY LINGERING RAIN TO SNOW...ESPECIALLY IN THE NORTH. THEN BASICALLY BENIGN WEATHER UNTIL THE NEXT SYSTEM APPROACHES FROM THE WEST ON FRIDAY. PRECIP WITH THAT EVENT LOOKS LIKE IT WILL BE MAINLY RAIN IN THE SOUTH WITH A LEAST A MIXTURE IN THE NORTH. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TONIGHT...CONDITIONS ARE FORECAST TO DETERIORATE TO MVFR OR IFR OVER ALL THE TAF SITES FROM NORTHWEST TO SOUTHEAST. THERE MAY BE A PERIOD WHEN THEY IMPROVE TO MVFR OR VFR ON SATURDAY MORNING BEFORE THEY MAY BEGIN TO DETERIORATE LATER IN THE DAY. WINDS SHOULD VEER FROM SOUTHWEST OR WEST TO NORTH DURING THE COURSE OF THE TAF PERIOD WITH SOME GUSTINESS TO AROUND 20 KT EARLY IN THE PERIOD AND PERHAPS AGAIN LATE. OUTLOOK... SATURDAY NIGHT...IFR CONDITIONS...ESPECIALLY SOUTH AND EAST OF I-95...IMPROVING TO VFR TOWARD MORNING. SUNDAY...MAINLY VFR AND BLUSTERY. POSSIBLE MVFR SNOW SHWRS NORTH. NORTHWEST WINDS GUSTING 25 TO 30 KNOTS. CONFIDENCE MODERATE. MONDAY AND MONDAY NIGHT...MAINLY VFR. CONFIDENCE HIGH. TUESDAY...LOWERING TO MVFR OR IFR IN MIXED PRECIPITATION IN THE MORNING. CHANCE OF LLWS. CONFIDENCE IS MODERATE. TUESDAY NIGHT...IMPROVING TO VFR. WEDNESDAY...MAINLY VFR. && .MARINE... SUB-ADVISORY CONDITIONS ARE FORECAST INTO SATURDAY, BUT THEN WILL APPROACH OR REACH ADVISORY CONDITIONS LATE IN THE DAY ON GOOD COLD AIR ADVECTION AND A NORTHWEST FLOW. SEAS SHOULD BUILD TO ADVISORY CONDITIONS BY LATE SATURDAY AFTERNOON. OUTLOOK... THE DEVELOPING AND DEEPENING OFFSHORE LOW OFF NORTH CAROLINA WILL CONTINUE SCA CONDITIONS OVER MARINE AREA (OCEAN AND DELAWARE BAY) WIDESPREAD SCA CONDITIONS THROUGH THE REMAIN PORTION OF THE WEEKEND. DEPENDING ON THE PATH OF THIS STORM...GALES ARE EVEN POSSIBLE SATURDAY NIGHT INTO SUNDAY ON THE OCEAN AND LOWER DELAWARE BAY. THIS SITUATION WILL BE RE- EXAMINED WITH LATER MODEL RUNS. A SOUTHWEST FLOW BEHIND AN ADVANCING WARM FRONT IS EXPECTED TO SCA BACK TO THE FORECAST WATERS ON TUESDAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...DRAG/MIKETTA 819 NEAR TERM...DRAG 819 SHORT TERM...DELISI LONG TERM...MIKETTA AVIATION...DELISI/DRAG/MIKETTA 819 MARINE...DELISI/DRAG/MIKETTA
AREA FORECAST DISCUSSION...UPDATED
NWS MIAMI FL
1250 PM EST THU FEB 14 2013 .AVIATION... THE STATIONARY FRONT HAS MOVED BACK NORTH INTO THE LAKE OKEECHOBEE AREA EARLY THIS AFTERNOON. THIS HAS ALLOWED FOR THE SKIES TO BECOME PARTLY CLOUDY OVER MOST OF THE TAF SITES EARLY THIS AFTERNOON...AND ALLOWED FOR THE EAST COAST SEA BREEZE TO SET UP ALONG THE EAST COASTAL AREAS. THE EAST COAST SEA BREEZE WILL CONTINUE TO PUSH SLOWLY INLAND THIS AFTERNOON ALLOWING FOR THE WINDS AT KFLL TO REMAIN EASTERLY AT 5 TO 10 KNOTS...AND SWING TO A EASTERLY DIRECTION AT KOPF TAF SITE AROUND 19Z AND THEN AT KMIA TAF SITE AROUND 20Z. REST OF THE TAF SITES SHOULD REMAIN IN A SOUTH TO SOUTHWEST DIRECTION THIS AFTERNOON AT 5 TO 10 KNOTS. WITH THE EAST COAST SEA BREEZE SETTING UP ALONG THE EAST COAST AREA AND THE SKIES BEING PARTLY CLOUDY...THIS WILL ALLOW FOR SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP OVER THE EASTERN AREAS OF THE CWA. SO HAVE INTRODUCE VCTS FOR ALL OF THE EAST COAST TAF SITES UNTIL 01Z...EXCEPT FOR KPBI WHERE VCSH WILL REMAIN...DUE TO THE FRONT LOCATED OVER THIS SITE. KAPF TAF SITE WILL ALSO ONLY SEE VCSH FOR THIS AFTERNOON. THE THUNDER THREAT OVER THE EAST COAST TAF SITES WILL COME TO AN END AROUND 00Z TO 01Z TONIGHT...AS THE HEATING OF THE DAY IS LOST AND THE WINDS BECOME MORE SOUTHWEST OVER THE TAF SITES AT 5 KNOTS OR LESS. AT THIS TIME THE VIS AND CEILING SHOULD REMAIN IN THE VFR CONDITIONS OUTSIDE OF ANY SHOWERS AND THUNDERSTORMS THAT DO DEVELOP. IN THE SHOWERS AND THUNDERSTORMS THE VIS AND CEILING COULD FALL DOWN INTO THE IFR CONDITIONS. && ...AVIATION...54/BNB .PREV DISCUSSION... /ISSUED 815 AM EST THU FEB 14 2013/ ..ISOLATED TSTORMS, SOME COULD CONTAIN STRONG WIND GUSTS AND LOCALLY HEAVY RAINFALL... UPDATE...WAVES OF HEAVY SHOWERS CONTINUE TO MOVE NE ACROSS COLLIER TO PALM BEACH COUNTIES. ONLY ONE LIGHTNING STRIKE NOTED JUST OFF THE COLLIER COAST A COUPLE OF HOURS AGO. GIVEN RADAR AND EXPECTED TRENDS, HAVE INCREASED POPS ACROSS THE AREA. HRRR SHOWS A GENERAL DECREASING TREND LATER THIS MORNING BEFORE THINGS REV BACK UP AGAIN THIS AFTERNOON...AND WITH SLIGHTLY BETTER HEATING ACROSS BROWARD AND MIAMI-DADE COUNTIES, TSTORMS COULD ERUPT ABOUT ANYWHERE BUT BETTER CHANCES THERE. MORNING ANALYSIS INDICATES THE POTENTIAL FOR A FEW STRONG TSTORMS WITH GUSTY WINDS TO AROUND 50 MPH. THERE IS SOME INCREASING INSTABILITY ALONG WITH AN INCOMING SHORTWAVE OVER THE GULF OF MEXICO WHICH COULD IGNITE A FEW STRONG TSTORMS, PARTICULARLY THIS AFTERNOON INTO EARLY THIS EVENING. TEMPS WERE LOWERED A BIT ACROSS SE AREAS SINCE CLOUDS ARE INCREASING FROM THE WEST. THEREFORE, MAX TEMPS IN THE LOWER 80S ARE NOW FORECAST WITH MID-UPPER 70S LAKE OKEECHOBEE REGION. && /GREGORIA PREV DISCUSSION... /ISSUED 621 AM EST THU FEB 14 2013/ AVIATION... COLD FRONT CURRENTLY NEAR A FORT LAUDERDALE TO EVERGLADES CITY LINE AND CLEARLY DEFINED BY BROKEN LINE OF SHRA BEHIND THE BOUNDARY. THE FRONT IS EXPECTED TO STALL ACROSS SOUTH FLORIDA BUT MODEL GUIDANCE DIFFERS JUST WHERE THE BOUNDARY BECOMES STATIONARY AND THIS WILL LIKELY PLAY HAVOC WITH THE WIND DIRECTION. AT ANY RATE, INCREASED CLOUD COVER WILL OCCUR WITH CHANCES OF RAIN ALSO INCREASING AT ALL TERMINALS THROUGH THE FORECAST WITH OCCASIONAL MVFR CIG/VSBY AND BRIEF IFR CANNOT BE RULED OUT EITHER. && KOB PREV DISCUSSION... /ISSUED 333 AM EST THU FEB 14 2013/ SHORT TERM... A COLD FRONT WILL CONTINUE TO SLOWLY MOVE INTO SOUTH FLORIDA AS TODAY PROGRESSES. MOISTURE ADVECTION WILL TAKE PLACE THROUGHOUT THE DAY LEADING TO AN INCREASED CHANCE OF RAIN. SINCE THIS FRONT WILL STALL OUT, IT LOOKS LIKE IT WILL BE A CLOUDY AND WET 48 HOUR PERIOD WITH SOME STEADY RAIN ALONG THE FRONT AS WELL AS THE POTENTIAL FOR SOME HEAVIER SHOWERS AND A FEW THUNDERSTORMS. INSTABILITY WILL BE RATHER LOW THROUGHOUT THE PERIOD WHICH WILL LIMIT THE THUNDERSTORM ACTIVITY, HOWEVER SOME EMBEDDED THUNDERSTORMS COULD DEVELOP. THE MAIN CONCERN WITH THIS FRONT WILL BE THE POTENTIAL FOR HEAVY RAIN. MODEL CONCENSUS IS SHOWING A WIDESPREAD AREA OF 1 TO 2 INCHES OF RAIN TODAY INTO FRIDAY. SOME AREAS COULD SEE LOCALIZED HIGHER TOTALS IN EXCESS OF 3 INCHES WHERE THE HEAVIER SHOWERS OR THUNDERSTORMS SET UP. THIS COULD RESULT IN ISOLATED URBAN FLOODING. HOWEVER, WIDESPREAD FLOOD PROBLEMS ARE NOT EXPECTED DUE TO THE DRY SPELL WE HAVE BEEN IN. LONG TERM... A STRONGER FRONT WILL BEGIN TO HELP MOVE ALL OF THE SHOWER AND THUNDERSTORM ACTIVITY OUT OF THE REGION BY FRIDAY NIGHT INTO EARLY SATURDAY MORNING. BEHIND THIS FRONT A STRONG AREA OF HIGH PRESSURE WILL BUILD IN FROM THE NORTH BRINGING IN MUCH COLDER TEMPERATURES TO THE REGION. THE STRONGEST PUSH OF COLD AIR WILL MOVE INTO THE REGION SATURDAY NIGHT AND SUNDAY. THE EXACT TIMING OF THIS IS STILL UNCERTAIN AS THE GFS IS SLIGHTLY SLOWER AND A LITTLE BIT WARMER ON SATURDAY NIGHT INTO SUNDAY, HOWEVER IT HAS BEEN TRENDING TOWARDS THE QUICKER AND COLDER ECMWF SOLUTION. THE FORECAST IS TRENDED TOWARDS THE ECMWF WHICH WOULD DROP TEMPERATURES INTO THE MID 30S IN GLADES AND HENDRY COUNTIES ON BOTH SUNDAY AND MONDAY MORNING. THERE COULD BE ISOLATED POCKETS OF TEMPERATURES DROPPING TO NEAR FREEZING IN THE COLDER LOCATIONS. WE WILL CONTINUE TO MONITOR THESE TRENDS. TEMPERATURES ON SUNDAY MORNING ACROSS THE SOUTHEASTERN METRO AREAS WILL BE IN THE MID TO UPPER 40S. COLD AIR ADVECTION WILL CONTINUE DURING THE DAY ON SUNDAY AS MANY AREAS WILL REMAIN IN THE MID TO UPPER 60S FOR DAYTIME HIGHS. THIS AREA OF HIGH PRESSURE WILL MOVE EAST OF THE AREA EARLY NEXT WEEK RESULTING MODERATING TEMPERATURES BY MONDAY AFTERNOON INTO TUESDAY WITH DRY CONDITIONS. MARINE... A COLD FRONT WILL STALL OUT OVER THE ATLANTIC AND GULF WATERS TODAY. THIS FRONT WILL REMAIN IN PLACE THROUGH FRIDAY CREATING A CHANCE OF SHOWERS AND A FEW THUNDERSTORMS. WINDS WILL REMAIN OUT OF THE SOUTH AT 10 TO 15 KNOTS THIS AFTERNOON. THE FRONT WILL MOVE TO THE SOUTH OF THE REGION ON FRIDAY NIGHT INTO SATURDAY. GUSTY NORTHWEST WINDS BEHIND THE FRONT MAY CREATE HAZARDOUS MARINE CONDITIONS THIS WEEKEND. FIRE WEATHER... MINIMUM RELATIVE HUMIDITY VALUES WILL REMAIN ABOVE CRITICAL VALUES ON THURSDAY NIGHT INTO FRIDAY. THESE VALUES ARE EXPECTED BE MUCH LOWER BEHIND THE FRONT ON SUNDAY AND MONDAY AFTERNOON. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 79 63 76 60 / 80 70 50 40 FORT LAUDERDALE 83 67 77 62 / 70 70 50 50 MIAMI 83 66 80 63 / 70 70 50 50 NAPLES 79 61 75 58 / 90 70 50 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...55/CWC AVIATION/RADAR...30/KOB
AREA FORECAST DISCUSSION
NWS MIAMI FL
815 AM EST THU FEB 14 2013 ...ISOLATED TSTORMS, SOME COULD CONTAIN STRONG WIND GUSTS AND LOCALLY HEAVY RAINFALL... .UPDATE...WAVES OF HEAVY SHOWERS CONTINUE TO MOVE NE ACROSS COLLIER TO PALM BEACH COUNTIES. ONLY ONE LIGHTNING STRIKE NOTED JUST OFF THE COLLIER COAST A COUPLE OF HOURS AGO. GIVEN RADAR AND EXPECTED TRENDS, HAVE INCREASED POPS ACROSS THE AREA. HRRR SHOWS A GENERAL DECREASING TREND LATER THIS MORNING BEFORE THINGS REV BACK UP AGAIN THIS AFTERNOON...AND WITH SLIGHTLY BETTER HEATING ACROSS BROWARD AND MIAMI-DADE COUNTIES, TSTORMS COULD ERUPT ABOUT ANYWHERE BUT BETTER CHANCES THERE. MORNING ANALYSIS INDICATES THE POTENTIAL FOR A FEW STRONG TSTORMS WITH GUSTY WINDS TO AROUND 50 MPH. THERE IS SOME INCREASING INSTABILITY ALONG WITH AN INCOMING SHORTWAVE OVER THE GULF OF MEXICO WHICH COULD IGNITE A FEW STRONG TSTORMS, PARTICULARLY THIS AFTERNOON INTO EARLY THIS EVENING. TEMPS WERE LOWERED A BIT ACROSS SE AREAS SINCE CLOUDS ARE INCREASING FROM THE WEST. THEREFORE, MAX TEMPS IN THE LOWER 80S ARE NOW FORECAST WITH MID-UPPER 70S LAKE OKEECHOBEE REGION. /GREGORIA && .PREV DISCUSSION... /ISSUED 621 AM EST THU FEB 14 2013/ AVIATION... COLD FRONT CURRENTLY NEAR A FORT LAUDERDALE TO EVERGLADES CITY LINE AND CLEARLY DEFINED BY BROKEN LINE OF SHRA BEHIND THE BOUNDARY. THE FRONT IS EXPECTED TO STALL ACROSS SOUTH FLORIDA BUT MODEL GUIDANCE DIFFERS JUST WHERE THE BOUNDARY BECOMES STATIONARY AND THIS WILL LIKELY PLAY HAVOC WITH THE WIND DIRECTION. AT ANY RATE, INCREASED CLOUD COVER WILL OCCUR WITH CHANCES OF RAIN ALSO INCREASING AT ALL TERMINALS THROUGH THE FORECAST WITH OCCASIONAL MVFR CIG/VSBY AND BRIEF IFR CANNOT BE RULED OUT EITHER. KOB PREV DISCUSSION... /ISSUED 333 AM EST THU FEB 14 2013/ SHORT TERM... A COLD FRONT WILL CONTINUE TO SLOWLY MOVE INTO SOUTH FLORIDA AS TODAY PROGRESSES. MOISTURE ADVECTION WILL TAKE PLACE THROUGHOUT THE DAY LEADING TO AN INCREASED CHANCE OF RAIN. SINCE THIS FRONT WILL STALL OUT, IT LOOKS LIKE IT WILL BE A CLOUDY AND WET 48 HOUR PERIOD WITH SOME STEADY RAIN ALONG THE FRONT AS WELL AS THE POTENTIAL FOR SOME HEAVIER SHOWERS AND A FEW THUNDERSTORMS. INSTABILITY WILL BE RATHER LOW THROUGHOUT THE PERIOD WHICH WILL LIMIT THE THUNDERSTORM ACTIVITY, HOWEVER SOME EMBEDDED THUNDERSTORMS COULD DEVELOP. THE MAIN CONCERN WITH THIS FRONT WILL BE THE POTENTIAL FOR HEAVY RAIN. MODEL CONCENSUS IS SHOWING A WIDESPREAD AREA OF 1 TO 2 INCHES OF RAIN TODAY INTO FRIDAY. SOME AREAS COULD SEE LOCALIZED HIGHER TOTALS IN EXCESS OF 3 INCHES WHERE THE HEAVIER SHOWERS OR THUNDERSTORMS SET UP. THIS COULD RESULT IN ISOLATED URBAN FLOODING. HOWEVER, WIDESPREAD FLOOD PROBLEMS ARE NOT EXPECTED DUE TO THE DRY SPELL WE HAVE BEEN IN. LONG TERM... A STRONGER FRONT WILL BEGIN TO HELP MOVE ALL OF THE SHOWER AND THUNDERSTORM ACTIVITY OUT OF THE REGION BY FRIDAY NIGHT INTO EARLY SATURDAY MORNING. BEHIND THIS FRONT A STRONG AREA OF HIGH PRESSURE WILL BUILD IN FROM THE NORTH BRINGING IN MUCH COLDER TEMPERATURES TO THE REGION. THE STRONGEST PUSH OF COLD AIR WILL MOVE INTO THE REGION SATURDAY NIGHT AND SUNDAY. THE EXACT TIMING OF THIS IS STILL UNCERTAIN AS THE GFS IS SLIGHTLY SLOWER AND A LITTLE BIT WARMER ON SATURDAY NIGHT INTO SUNDAY, HOWEVER IT HAS BEEN TRENDING TOWARDS THE QUICKER AND COLDER ECMWF SOLUTION. THE FORECAST IS TRENDED TOWARDS THE ECMWF WHICH WOULD DROP TEMPERATURES INTO THE MID 30S IN GLADES AND HENDRY COUNTIES ON BOTH SUNDAY AND MONDAY MORNING. THERE COULD BE ISOLATED POCKETS OF TEMPERATURES DROPPING TO NEAR FREEZING IN THE COLDER LOCATIONS. WE WILL CONTINUE TO MONITOR THESE TRENDS. TEMPERATURES ON SUNDAY MORNING ACROSS THE SOUTHEASTERN METRO AREAS WILL BE IN THE MID TO UPPER 40S. COLD AIR ADVECTION WILL CONTINUE DURING THE DAY ON SUNDAY AS MANY AREAS WILL REMAIN IN THE MID TO UPPER 60S FOR DAYTIME HIGHS. THIS AREA OF HIGH PRESSURE WILL MOVE EAST OF THE AREA EARLY NEXT WEEK RESULTING MODERATING TEMPERATURES BY MONDAY AFTERNOON INTO TUESDAY WITH DRY CONDITIONS. MARINE... A COLD FRONT WILL STALL OUT OVER THE ATLANTIC AND GULF WATERS TODAY. THIS FRONT WILL REMAIN IN PLACE THROUGH FRIDAY CREATING A CHANCE OF SHOWERS AND A FEW THUNDERSTORMS. WINDS WILL REMAIN OUT OF THE SOUTH AT 10 TO 15 KNOTS THIS AFTERNOON. THE FRONT WILL MOVE TO THE SOUTH OF THE REGION ON FRIDAY NIGHT INTO SATURDAY. GUSTY NORTHWEST WINDS BEHIND THE FRONT MAY CREATE HAZARDOUS MARINE CONDITIONS THIS WEEKEND. FIRE WEATHER... MINIMUM RELATIVE HUMIDITY VALUES WILL REMAIN ABOVE CRITICAL VALUES ON THURSDAY NIGHT INTO FRIDAY. THESE VALUES ARE EXPECTED BE MUCH LOWER BEHIND THE FRONT ON SUNDAY AND MONDAY AFTERNOON. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 79 63 76 60 / 80 70 50 40 FORT LAUDERDALE 83 67 77 62 / 70 70 50 50 MIAMI 83 66 80 63 / 70 70 50 50 NAPLES 79 61 75 58 / 90 70 50 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
335 AM EST THU FEB 14 2013 .SYNOPSIS... 08Z WATER VAPOR AND H4 RAP ANALYSIS SHOW BROAD LONGWAVE TROUGHING IN PLACE OVER MUCH OF THE CONUS. FEATURE EMBEDDED WITHIN THIS LARGER SCALE FLOW THAT WILL HAVE THE MOST SHORT TERM INFLUENCE IS A SHORTWAVE IMPULSE EJECTING EASTWARD FROM THE SOUTHERN PLAINS/NORTHERN MEXICO. THIS FEATURE WILL MOVE SLOWLY EASTWARD TOWARD THE FL PENINSULA INTO FRIDAY KEEPING OUR AREA WITHIN IN A REGION OF BROAD SYNOPTIC ASCENT/QG FORCING. WV IMAGERY SHOWS THAT WE HAVE NO LACK OF MID/UPPER LEVEL MOISTURE STREAMING ACROSS THE NORTHERN GULF AND CENTRAL/NORTHERN FL PENINSULA FOR THIS BROAD LIFT TO ACT ON. AT THE SURFACE...COLD FRONT CONTINUES TO VERY SLOW DRIFT SOUTH AND EAST INTO THE SOUTHERN FLORIDA PENINSULA. THE BOUNDARY HAS NOW CLEARED ALL OF OUR FORECAST AREA WITH COOLER AND DRIER LOW LEVEL AIR TRYING TO FILTER IN FROM THE NORTH. THIS DRY AIR WILL ONLY BE IN THE VERY LOWEST LEVELS...AND SHOWERS WILL REMAIN IN THE FORECAST...EVEN IN THE POST-FRONTAL ENVIRONMENT. REGIONAL RADARS...SHOW A SCATTERING OF LIGHT SHOWER ACTIVITY ACROSS THE REGION EARLY THIS MORNING...WITH A FEW HEAVIER CELLS DOWN OVER THE SOUTHERN PENINSULA IN CLOSER PROXIMITY TO THE FRONTAL FOCUS. && .SHORT TERM (TODAY THROUGH SATURDAY)... TODAY/TONIGHT... SURFACE BOUNDARY WILL BECOME STALLED THIS MORNING ACROSS THE SE GULF AND FAR SOUTHERN FL PENINSULA...AND THEN REMAIN IN PLACE THROUGH TONIGHT. MID/UPPER LEVEL SHORTWAVE IMPULSE WILL GRADUALLY ELONGATE AND MOVE EASTWARD ACROSS THE NORTHERN GULF TOWARD THE REGION. THE RAINFALL FORECAST REMAINS A TRICKY ONE AS THE FORCING MECHANISMS ARE ALL RATHER BROAD WITH NOTHING OBVIOUS TO FOCUS THE LIFT IN ONE PLACE VS ANOTHER. OVERALL...STILL FEEL THE MOST WIDESPREAD SHOWERS ACTIVITY WILL EVENTUALLY DEVELOP BY LATER TODAY AND INTO THE OVERNIGHT ALONG AND TO THE SOUTH OF THE I-4 CORRIDOR...WHERE LARGE SCALE QG FORCING WILL BECOME COINCIDENT WITH WELL DEFINED DIFFLUENCE ALOFT...AND AT LEAST SOME LOW LEVEL UPGLIDE TO THE NORTH OF THE SURFACE BOUNDARY. FOR THIS MORNING...ONE DEPARTING JET STREAK UP THE EASTERN SEABOARD IS SUPPORTING A SWATH OF GOOD DIVERGENCE ALOFT AND A BAND OF SHOWERS/RAIN ACROSS APALACHEE BAY AND THE FL BIG BEND. GUIDANCE SUGGESTS THAT ALTHOUGH THIS DIVERGENCE WILL BE PULLING AWAY WITH TIME...INCREASING CHANCES FOR SHOWERS WILL ONCE AGAIN ARRIVE ACROSS OUR NORTHERN NATURE COAST ZONES FOR A TIME THIS MORNING. BY THE AFTERNOON...THESE DYNAMICS WILL BE ESSENTIALLY GONE AND THINK THE BEST FOCUS FOR SHOWERS SHIFTS SOUTHWARD. HAVE CHANCE POPS THIS MORNING FOR ALL WITH A BAND OF LIKELY UP TOWARD LEVY COUNTY FOR REASONS DISCUSSED ABOVE. THEREAFTER FOR THE AFTERNOON AND EVENING KEPT CHANCE POPS NORTH OF TAMPA BAY WITH LIKELY TO CATEGORICAL RAIN CHANCES ALONG THE I-4 CORRIDOR AND SOUTHWARD. TEMPERATURES WILL DEPEND HIGHLY ON THE EVENTUAL RAINFALL PATTERNS AND ARRIVAL TIMING...BUT MID 60S FAR NORTH RANGING TO LOWER 70S MID ZONES...AND MID/UPPER 70S SOUTH SHOULD WORK WELL. LOW TEMPS TONIGHT WILL RANGE FROM THE 40S FAR NORTH TO THE LOW/MID 50 MID ZONES...AND MID 50S TO AROUND 60 FAR SOUTH. SOME OF THE STATISTICAL GUIDANCE WANTS TO BRING TEMPS DOWN INTO THE 30S FAR NORTH...BUT FEEL WITH THE AMOUNT OF CLOUDS AND POTENTIAL FOR AT LEAST SOME RESIDUAL SHOWERS ACTIVITY...EVEN AS FAR NORTH AS LEVY COUNTY...THAT 30S ARE UNLIKELY. FRIDAY/FRIDAY NIGHT... SHORTWAVE AXIS PASSES TO OUR EAST EARLY IN THE DAY WITH A DECLINE IN THE LARGE SCALE FORCING. UPPER JET CONFIGURATION FAVORS LESS AND LESS DIFFLUENCE ALOFT AS WELL. EXPECT A SCATTERING OF SHOWERS TO STILL BE ONGOING DURING THE MORNING HOURS...ESPECIALLY SOUTH AND EAST OF TAMPA BAY IN CLOSER PROXIMITY TO THE SURFACE BOUNDARY. THIS ACTIVITY SHOULD SLOWLY PIVOT EASTWARD AND AWAY FROM OUR ZONES LATER FRIDAY AND ESPECIALLY FRIDAY EVENING AS A BIG PATTERN CHANGE FOR THE UPCOMING WEEKEND BEGINS TO RAPIDLY EVOLVE TO OUR NORTHWEST. SO...SCATTERED SHOWERS (BUT NOT A WASHOUT) EXPECTED FROM TAMPA BAY/POLK COUNTY SOUTHWARD ON FRIDAY...WITH THIS ACTIVITY ENDING FOR ALL ZONES DURING FRIDAY NIGHT. UPPER LEVEL PATTERN WILL BE AMPLIFYING OVER THE EASTERN HALF OF THE NATION ON FRIDAY...WITH A STRONG SHORTWAVE IMPULSE WORKING DOWN THE BACKSIDE OF THE TROUGH. THIS ENERGY WILL ACT TO REALLY SHARPEN THE FLOW FRIDAY NIGHT INTO SATURDAY ACROSS THE SOUTHEASTERN STATES/FL PENINSULA. FIRST BOUNDARY ASSOCIATED WITH THIS TROUGH LOOKS TO QUICKLY CROSS THE AREA FRIDAY NIGHT...WITH CAA INTENSIFYING AFTER MIDNIGHT. WILL SEE WIDESPREAD TEMPS IN THE 40S BY EARLY SATURDAY MORNING. SOME UPPER 30S ARE LIKELY ACROSS THE NATURE COAST...AND 50S AT THE IMMEDIATE COAST FROM PINELLAS COUNTY SOUTHWARD. SATURDAY... SHARP SHORTWAVE IMPULSE EJECTS ACROSS THE PENINSULA SURGING A REINFORCING COLD FRONT ACROSS THE AREA DURING THE DAY. THIS FRONT WILL HAVE A DRY PASSAGE...BUT WILL DELIVER ONE OF THE COLDEST (IF NOT THE COLDEST) OVERALL LOW LEVEL COLUMNS OF THE WINTER SO FAR. 850MB TEMPS WILL DROP BELOW ZERO ACROSS AT LEAST THE CENTRAL AND NORTHERN PORTIONS OF THE FORECAST AREA. GFS 850MB TEMPS BY SATURDAY EVENING ARE ON THE ORDER OF 3-3.5 STANDARD DEVIATIONS BELOW CLIMO FOR MID FEBRUARY. THE GFS TENDS TO HAVE A COLD BIAS IN ITS 850MB TEMPS...BUT EVEN TAKING THIS BIAS INTO CONSIDERATION...A BIG COOL DOWN IN IN STORE FOR THE WEEKEND. WINDS WILL BECOME GUSTY SATURDAY AFTERNOON BEHIND THIS SECONDARY FRONT...ESPECIALLY CLOSE TO THE COAST...AND IT WILL FEEL QUITE COOL FOR OUTDOOR ACTIVITIES. MORE ON THIS BRIEF...BUT SHARP COLD SNAP IN THE LONG RANGE DISCUSSION BELOW. && .LONG TERM (SUNDAY THROUGH NEXT WEDNESDAY)... THE MAIN STORY IN THE EXTENDED FORECAST CONTINUES TO BE THE COLD TEMPERATURES OVER THE UPCOMING WEEKEND. WE WILL LIKELY BE DEALING WITH FREEZING TEMPERATURES FOR PORTIONS OF OUR AREA BOTH SATURDAY NIGHT AND SUNDAY NIGHT. SATURDAY NIGHT WILL BE AN ADVECTIVE FREEZE WITH SOME WIND CHILL ISSUES AS WELL. SUNDAY NIGHT WILL BE MORE OF A RADIATIONAL COOLING FREEZE. TEMPERATURES BOTH NIGHTS COULD END UP QUITE SIMILAR...BUT IT WILL PROBABLY FEEL COLDER SATURDAY NIGHT WITH WINDS AROUND 10 MPH. RIGHT NOW EXPECT WIDESPREAD TEMPERATURES BETWEEN 28 AND 32 DEGREES BOTH NIGHTS FROM ABOUT HERNANDO COUNTY NORTHWARD. SOUTH OF THERE...I AM LEANING TOWARD MID 30S OVER THE INTERIOR. IF SKIES STAY CLEAR SUNDAY NIGHT AND WE COMPLETELY DECOUPLE LEADING TO CALM WINDS...FREEZING TEMPERATURES WILL EXTEND MUCH FARTHER SOUTH. THIS IS ALL STILL BEYOND 72 HOURS OUT SO NO WATCHES ARE NEEDED YET AND THERE IS STILL PLENTY OF TIME TO REFINE THE FORECAST. AS QUICK AS THE COLD AIR MOVES IN...IT MOVES BACK OUT. SUNDAY WILL BE THE COLDEST DAY WITH HIGHS ONLY IN THE UPPER 50S TO NEAR 60 FROM TAMPA BAY NORTH AND IN THE LOWER TO MIDDLE 60S WELL TO THE SOUTH. ON MONDAY WE WILL BE 10 DEGREES WARMER THAN THAT WHICH BRINGS US BACK TO NEAR NORMAL. WE WILL BE IN A VERY PROGRESSIVE PATTERN THROUGH MID-WEEK AND BEYOND WITH COLD FRONTS ARRIVING ABOUT EVERY THIRD DAY. THE NEXT CHANCE OF RAIN WILL BE LATE TUESDAY AND TUESDAY NIGHT FOLLOWED BY DRIER...AND SOMEWHAT COOLER AIR ON WEDNESDAY. && .AVIATION... THE LAST BATCH OF HEAVIER SHOWERS IS MOVING THROUGH FMY AND RSW NOW. THE REST OF THE REGION SHOULD SEE MAINLY VFR CONDITIONS THROUGH MID AFTERNOON OR SO. RAIN IS EXPECTED TO REDEVELOP OVER THE GULF LATER WHICH SHOULD BRING MVFR CEILINGS TO ALL TERMINALS THROUGH THE EVENING HOURS. THE NORTHERN TERMINALS HAVE THE BEST CHANCE AT RETURNING TO VFR AFTER 00Z WHILE THE SOUTHERN TERMINALS COULD SEE AN EXTENDED PERIOD OF MVFR OR PERHAPS EVEN IFR CEILINGS LASTING INTO THE MORNING HOURS FRIDAY. && .MARINE... FRONTAL BOUNDARY WILL STALL JUST SOUTH OF THE FORECAST WATERS THROUGH FRIDAY HELPING TO KEEP PERIODS OF RAIN/SHOWERS ACROSS THE EASTERN GULF THE NEXT 24 HOURS. NORTH TO NORTHEAST FLOW WILL OCCASIONALLY APPROACH CAUTIONARY LEVELS...ESPECIALLY SOUTH OF TAMPA BAY THROUGH THIS EVENING WITH ALL ZONES REMAINING BELOW HEADLINE CRITERIA ON FRIDAY. ANOTHER STRONGER BUT DRY FRONT WILL QUICKLY MOVE THROUGH THE EASTERN GULF OF MEXICO FRIDAY NIGHT AND SATURDAY MORNING WITH WINDS AND SEAS RAPIDLY BUILDING TO ADVISORY LEVELS FROM THE NORTHWEST FOR MUCH OF SATURDAY AND SATURDAY NIGHT. WINDS AND WAVES WILL GRADUALLY SUBSIDE INTO SUNDAY AS HIGH PRESSURE BUILDS OVER THE REGION. && .FIRE WEATHER... RELATIVE HUMIDITY WILL REMAIN WELL ABOVE CRITICAL LEVELS TODAY. THE ONE CONCERN WILL HOWEVER BE FOR LOW DISPERSION INDICES THROUGH THE DAY. SOMEWHAT DRIER AIR WILL BEGIN TO ARRIVE OVER THE NORTHERN ZONES FOR FRIDAY AND A BRIEF PERIOD OF RELATIVE HUMIDITY BELOW 35 PERCENT IS POSSIBLE FOR LEVY/CITRUS AND SUMTER COUNTIES. DESPITE THE DRY AIR UP NORTH...ERC VALUES ARE LOW...AND DISPERSION INDICES WILL REMAIN LOW AS WELL. THESE CONDITIONS SHOULD PREVENT ANY RED FLAG CONDITIONS FROM BEING MET. MUCH DRIER AIR ARRIVES FOR ALL ZONES ON SATURDAY... ALONG WITH GUSTY NORTHWEST WINDS BY THE AFTERNOON HOURS. WILL NEED TO MONITOR CONDITIONS CLOSELY FOR SATURDAY AS LOW RELATIVE HUMIDITY...GUSTY WINDS...AND HIGH DISPERSIONS MAY ALLOW FOR SOME BRIEF RED FLAG CONDITIONS. && PRELIMINARY POINT TEMPS/POPS... TPA 69 55 69 51 / 80 50 30 10 FMY 76 62 73 55 / 90 70 50 30 GIF 72 53 71 47 / 80 60 30 10 SRQ 69 56 70 52 / 80 60 30 20 BKV 68 50 70 41 / 60 50 20 10 SPG 68 58 69 56 / 80 60 30 10 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR CHARLOTTE- LEE. GULF WATERS...NONE. && $$ SYNOPSIS/SHORT TERM/MARINE/FIRE WEATHER...MROCZKA LONG TERM/AVIATION/DECISION SUPPORT SERVICES...JILLSON
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
320 PM CST THU FEB 14 2013 .SYNOPSIS... 18Z SURFACE ANALYSIS INDICATED LOW PRESSURE OVER NORTHERN LOWER MI WITH A TROUGH OR WEAK COLD FRONT REACHING SOUTH-SOUTHWEST ACROSS IL...MO INTO EASTERN OK. A SECOND REINFORCING COLD FRONT EXTENDED WEST FROM THE LOW ACROSS WI TO ALONG THE IA/MN BORDER. SOUTH OF THIS FRONT...TEMPERATURES WERE IN THE 30S TO LOWER 40S WITH BRISK W-NW WINDS ACROSS THE FORECAST AREA. ALOFT...A BROAD CYCLONIC FLOW ENCOMPASSED THE EASTERN 2/3RDS OF THE CONTINENTAL U.S. THERE WERE A SERIES OF SHORTWAVES EMBEDDED IN THIS FLOW FROM THE GREAT LAKES TO THE CANADIAN ROCKIES. THE FOCUS IN THE SHORT TERM IS A VORT MAX EVIDENT ON SATELLITE WV IMAGES OVER N CENTRAL IA...WHERE AREA RADARS AND SURFACE REPORTS WERE INDICATING SNOW SHOWERS. && .SHORT TERM...TONIGHT AND FRIDAY... MAIN FOCUS IS ON THE SNOW SHOWERS THAT WILL OVERSPREAD THE AREA LATE THIS AFTERNOON AND EVENING...THEN COOLER TEMPERATURES AND POTENTIAL FLURRIES THROUGH FRIDAY. AN AXIS OF ROTATION SEEN IN RECENT KDMX 88D LOOPS INDICATED THE UPSTREAM VORT MAX WAS CENTERED ROUGHLY NORTH OF WEBSTER CITY AT 20Z. THIS WAS WELL SOUTH OF THE OPERATIONAL NAM...GFS AND ECMWF TRACKS FROM THIS MORNING. THE RECENT RAP RUNS APPEARED TO HAVE A DECENT CAPTURE OF THIS VORT CENTER AND WILL FOLLOW ITS OVERALL SOUTHEASTWARD TRACK. THIS WILL SEND THE UPSTREAM SNOW SHOWERS... TRENDING HEAVIEST ALONG AND NORTH OF THE VORT MAX...SOUTHEAST THROUGH THE EAST CENTRAL IA AND THEN W CENTRAL IL OVER THE NEXT SEVERAL HOURS. COLD ADVECTION ALOFT WAS SHOWN LEADING TO STEEP MID LEVEL LAPSE RATES ON THE ORDER OF 7 TO 8 DEG C/KM IN THIS MORNING/S MODEL RUNS. THIS...COMBINED WITH THE UPPER LEVEL FORCING AND LIFT ALONG THE SOUTHWARD MOVING COLD FRONT WILL SUPPORT CONTINUED LIGHT TO MODERATE SNOW SHOWERS AND AT LEAST LIGHT ACCUMULATIONS. THE HIGH RES RAP CONTINUES TO INDICATE QPF VALUES IN THE RANGE OF .2 TO .3 INCHES AS SNOW SHOWERS TRACK FROM ABOUT CID THROUGH THE QUAD CITIES TO NEAR KEWANEE BETWEEN 23Z AND 05Z AND HAVE LIKELY POPS ALONG THIS AXIS. WHILE THIS LOOKS OVERDONE BASED ON MEAGER PRECIPITATION AMOUNTS REPORTED SO FAR AT AUTOMATED UPSTREAM SITES...CANNOT RULE OUT BANDS OF 1 TO POSSIBLY 2 INCH SNOW ACCUMULATIONS IF THE CONVECTION TAPS INTO THE DEEPER INSTABILITY OVER THE NEXT SEVERAL HOURS. BASED ON THE INITIAL WARM LOW LEVELS AND TEMPERATURES IN THE 30S TO LOWER 40S LEADING TO A RAIN/SNOW MIX AT ONSET...WILL STAY CLOSE TO A MORE CONSERVATIVE .5 TO 1 INCH SNOWFALL RANGE FOR NOW AND WATCH TRENDS CLOSELY. THE CURRENT PACE OF THE VORT MAX SHOULD SEND THE SHOWERS EAST OF THE AREA BY MID EVENING...AND HAVE ONLY SLIGHT CHANCE POPS AFTER MIDNIGHT IN THE EAST AND SOUTHEAST. THE COLD FRONT SHOULD SLIDE THROUGH THE ENTIRE AREA BY MIDNIGHT...FOLLOWED BY PARTIAL CLEARING BASED ON SATELLITE TRENDS. GUIDANCE LOWS BY SUNRISE IN THE MID TEENS NORTH TO MID 20S SOUTH LOOK REASONABLE. FRIDAY...WILL KEEP A MENTION OF SCATTERED FLURRIES GOING IN THE FORECAST BASED ON THE STREAM OF WEAK IMPULSES AND MID LEVEL MOISTURE IN THE CYCLONIC FLOW ALOFT. CLOUD COVER AND COLD AIR ADVECTION SHOULD LIMIT THE DIURNAL TEMPERATURE RISE. HAVE STAYED CLOSE TO THE PREVIOUS FORECAST AND LATEST MODEL GUIDANCE WITH HIGHS RANGING FROM THE LOWER 20S NORTH TO LOWER 30S SOUTH. SHEETS .LONG TERM...FRIDAY NIGHT THROUGH NEXT THURSDAY FRIDAY NIGHT AND SATURDAY WE REMAIN IN THE NORTHWEST CYCLONIC FLOW AND STEEP MID LEVEL LAPSE RATES WITH ENOUGH LOW LEVEL MOISTURE TO ALLOW FOR FLURRIES DURING THE OVERNIGHT AND SATURDAY MORNING. WE ALSO HAVE SOME UPPER LEVEL VORT MAXES THAT SHOULD ALSO HELP TO TRIGGER THESE FLURRIES. THERE IS NOT REALLY ENOUGH MOISTURE FOR MORE THAN THAT...THOUGH A DUSTING IS POSSIBLE IF REPEAT ACTIVITY AFFECTS THE SAME AREA. TEMPERATURES TO REMAIN COLD THROUGH SATURDAY WITH HIGHS SATURDAY IN THE 20S TO AROUND 30. WARMED MINS FRIDAY NIGHT DUE TO THE EXTRA CLOUD COVER AND RANGE FROM 10-20. STRONG WARM AIR ADVECTION SETS IN OVER THE AREA AT 850MB SATURDAY NIGHT AND SUNDAY. THIS IS LIKELY TO BRING ANOTHER BAND OF CLOUD COVER ACROSS THE AREA OVERNIGHT AND SUNDAY MORNING. SATURDAY NIGHT MINS ARE LIKELY TO NOT SHOW MUCH CHANGE YET AS MOST OF THE WARMING IS ALOFT. SUNDAY HOWEVER WE ARE LIKELY TO SEE A BIG WARM-UP WITH HIGHS IN THE MID 30S NORTHEAST TO THE UPPER 40S SOUTHWEST. TEMPERATURES APPROACHING 50 ARE POSSIBLE IF WE CAN CLEAR OUT AND MIX DEEPLY ENOUGH. THE NEXT PUZZLE OF THE DAY IS MONDAY AND MONDAY NIGHT AS OUR NEXT STRONG STORM SYSTEM CROSSES THE MIDWEST. A RELATIVELY SHALLOW LONGWAVE TROUGH MOVES ACROSS THE AREA WITH TWO SEPARATE PIECES OF ENERGY...ONE FARTHER NORTH THAT GENERATES A SURFACE LOW OVER SOUTHERN MINNESOTA BY MONDAY MORNING. ANOTHER PIECE OF ENERGY IS OVER NEW MEXICO WHICH GENERATES A SURFACE LOW OVER OKLAHOMA AT THE SAME TIME. THIS SYSTEM SWEEPS OUT ACROSS THE MIDWEST MONDAY AND MONDAY NIGHT. MODELS HAVE BEEN VARYING ON HOW WELL PHASED THESE SYSTEMS WILL BE OVER THE PAST COUPLE DAYS AS WELL AS HOW MUCH ENERGY WILL BE WITH EACH. THUS...THE IMPACT FOR OUR CWA HAS VARIED FROM DRY TO A RAIN/SNOW MIX. FOR NOW MODELS ARE COMING IN A LITTLE SLOWER AND STRONGER...AND ARE BRINGING MORE MOISTURE AND WARMTH INTO THE AREA. THUS...HAVE RAISED POPS THROUGH THE PERIOD. ALSO...HAVE CONVERTED MONDAY TO NEARLY ALL RAIN...WITH JUST A RAIN SNOW MIX ACROSS THE NORTH. MONDAY NIGHT WE GRADUALLY SWITCH TO ALL SNOW...BUT THE TIMING IS STILL VERY MUCH UP IN THE AIR. DUE TO THE START BEING ALL RAIN...SNOWFALL AMOUNTS WILL BE LIGHT. TUESDAY AND WEDNESDAY ARE RELATIVELY QUIET WITH A STRONG SURFACE RIDGE BUILDING INTO THE AREA FOR DRY AND COLD CONDITIONS. IN FACT...IF WE CAN GET DECENT RADIATIONAL CONDITIONS FOR TUESDAY NIGHT MIN TEMPS COULD DIP INTO THE SINGLE DIGITS OVER A FAIRLY LARGE PORTION OF THE AREA. HOWEVER...THIS IS STILL SOMEWHAT QUESTIONABLE AND HAVE STAYED A LITTLE WARMER FOR NOW. THE BIG QUESTION OF THE FORECAST COMES THURSDAY. FOR SEVERAL MODEL RUNS NOW...THE ECMWF AND GFS HAVE BEEN ADVERTISING A VERY STRONG STORM FOR THE MIDWEST ON THURSDAY AND FRIDAY. THERE IS REMARKABLE CONSISTENCY AND CONFIDENCE IS GROWING THAT SOMEWHERE IN THE MIDWEST THERE WILL BE A MAJOR WINTER STORM...IF NOT A BLIZZARD. HOWEVER...WHETHER OUR AREA WILL BE AFFECTED OR NOT IS VERY MUCH IN QUESTION. WE CURRENTLY HAVE DIFFERING MODEL SOLUTIONS...ONE OF WHICH DEPICTS THE WINTER STORM AFFECTING THE CWA WITH MAJOR SNOW ACCUMULATIONS...ANOTHER WHICH BRINGS IN MORE WARM AIR AND AFFECTS US WITH ANOTHER RAIN/SNOW MIX EVENT WITH LESSER ACCUMULATIONS. IN GENERAL PREFER THE MORE CONSISTENT AND BETTER VERIFYING ECMWF WHICH HAS THE LARGER SNOW ACCUMULATIONS...BUT CANNOT TOTALLY DISCOUNT THE WARMER GFS EITHER. WE WILL HAVE TO WATCH THIS STORM VERY CAREFULLY OVER THE NEXT SEVERAL DAYS TO MONITOR THESE TRENDS. YOU WILL DEFINITELY WANT TO KEEP UP WITH THE LATEST INFORMATION REGARDING THIS WINTER STORM SYSTEM. FOR NOW THE LATEST FORECAST REFLECTS A BLENDED APPROACH...AND WE WILL HAVE TO REFINE WITH LATER FORECASTS. ..LE.. && .AVIATION... AN UPPER LEVEL DISTURBANCE AND SOUTHWARD MOVING SURFACE COLD FRONT WILL COMBINE TO PRODUCE SNOW SHOWERS OVER EASTERN IA INTO NW IL THIS AFTERNOON AND EVENING. THIS WILL CAUSE CIGS TO LOWER TO MVFR THIS EVENING. SNOW SHOWERS AND POSSIBLE IFR VISIBILITIES NOW APPEAR MOST LIKELY TO AFFECT THE CID AND MLI TERMINALS...MAINLY IN A WINDOW BETWEEN 22Z AND 03Z THIS EVENING. WEST TO NW WINDS FROM 14 TO 24 KTS WILL DIMINISH AND VEER TO MORE PREDOMINANTLY NORTHWEST DURING THIS TIME. OVERNIGHT...AT LEAST PARTIAL CLEARING OF CLOUDS IS EXPECTED WITH CONDITIONS IMPROVING TO VFR. AN UNSETTLED PATTERN WILL CONTINUE INTO FRIDAY...WITH PREVAILING VFR CONDITIONS EXPECTED WITH POSSIBLE FLURRIES THROUGH THE DAY. SHEETS && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SHEETS/LE
AREA FORECAST DISCUSSION
NWS DES MOINES IA
310 PM CST THU FEB 14 2013 .SHORT TERM /TONIGHT/... FORECAST CONCERN IS FOCUSED ON QUICK MOVING SHORTWAVE TO BRING SOME LIGHT PRECIP TO THE FORECAST AREA THROUGH THIS EVENING. WEAK BROAD FORCING ALONG THE COLD FRONT WILL BRING LIGHT SNOW OR RAIN THROUGH THE LATE AFTERNOON BEFORE SWITCHING OVER TO ALL SNOW AFTER 00Z FRIDAY. BUFR SOUNDINGS SHOWING BRIEF WINDOW OF FAIRLY DEEP SATURATION FROM 21Z OR CURRENTLY THROUGH 03Z FRIDAY. COLUMN LOSES ICE INTRODUCTION AND FORCING ACROSS NORTHERN IOWA B/T 00-03Z. BELIEVE MODELS ARE BIT SLOW WITH MOVING THIS SYSTEM OUT AND CUT BACK ON POPS PAST 03Z. 17Z HRRR QUICKLY DIMINISHES PRECIP BY 02Z WHICH COINCIDES WITH SEVERAL OF THE HIRES WRF MODELS AND NAM12. ALSO DECREASED SNOW AMOUNTS WITH THE QUICKER MOVEMENT...WEAKER FORCING AND LESS MOISTURE AVAILABLE. .LONG TERM /FRIDAY THROUGH THURSDAY/... COLD AIR SETTLING INTO THE REGION BY 12Z FRIDAY WITH GENERALLY A CLOUDY DAY IN STORE. LINGERING FLURRIES WILL BE POSSIBLE FRIDAY WITH WEAK WAVE PASSING THROUGH THE REGION DURING THE DAYTIME HOURS. OTHERWISE TEMPERATURES WILL CREEP BACK UP DURING THE DAY TO NEAR 20 NORTH AND THE LOWER 30S IN THE SOUTH. AS HIGH BUILDS SOUTH FRIDAY NIGHT SKIES WILL CLEAR OUT AND COLDER NIGHT IN STORE. LOWS WILL DROP OFF INTO THE SINGLE DIGITS NORTH WITH THE TEENS IN THE SOUTHEAST. H850 TEMPS REMAIN RATHER COLD THROUGH THE EARLY PART OF THE FORECAST BUT AS THE RIDGE AXIS SLIPS EAST SATURDAY EVENING...TEMPS WARM OVERNIGHT INTO SUNDAY MORNING. WARM AIR ADVECTION WILL INITIATE CLOUDS WITH GENERALLY LIGHT FLOW OVERNIGHT. BY SUNDAY MED RANGE MODELS CONTINUE WITH PREVIOUS RUNS TO SHOW DECENT WARM UP BY LATE DAY. H850 TEMPS WARM TO NEAR 0C NORTHEAST AND TO NEAR 4-5C SOUTHWEST AND WEST BY 00Z. THIS BODES WELL FOR TRENDS OF HIGHS IN THE 50S ACROSS THE SOUTHWEST PORTION OF THE FORECAST AREA WITH HIGHS ABOVE THE FREEZING MARK IN THE NORTHEAST. AS THE NEXT UPSTREAM WAVE APPROACHES THE AREA ANOTHER STRONG COLD FRONT WILL PASS SOUTHEAST THROUGH IOWA ON MONDAY. LIFT ASSOCIATED WITH IT WILL ALLOW FOR A RAIN OR RAIN/SNOW MIXTURE TO OCCUR SOUTHEAST BY LATE IN THE AFTERNOON. ANOTHER STRETCH OF COLDER THAN NORMAL WEATHER IS ANTICIPATED FOR THE EARLY PORTION OF NEXT WEEK WITH A SLOW MODERATION TOWARD THURSDAY...BUT STILL BELOW THE FREEZING MARK. MED RANGE MODELS STILL PAINT AN ACTIVE STORM OVER THE FORECAST AREA BY LATE WED OR EARLY THURSDAY WITH THE MAIN PORTION OF THE STORM TO HIT THURSDAY THROUGH FRIDAY. SIGNATURE HAS SHOWN UP FOR TWO DAYS NOW IN MOST MED RANGE MODELS...BUT EVEN SO...AT SEVEN DAYS OUT THERE ARE STILL TO BE MANY CHANGES IN THE TRACK AND DETAILS. AT THIS TIME WILL EMPHASIZE ONLY A STRONGER SYSTEM OVER THE CENTRAL STATES LOOKS MORE LIKELY BUT WAY TOO EARLY TO BECOME OVERLY EXCITED ABOUT MODEL DETAILS...ESPECIALLY GIVEN THAT THE 12Z GFS IS ABOUT 10 MB STRONGER THAN THE 12Z EURO MODEL TODAY. && .AVIATION...14/18Z INTERMITTENT MVFR STRATUS WILL PERSIST THROUGH THE AFTERNOON AND LOW CONFIDENCE WITH AN EXTENDED PERIOD OF MVFR STRATUS...BUT HIGH ENOUGH TO MENTION TIMING WITH A TEMPO. COLD FRONT DRAPED ACROSS NORTHERN IOWA WILL CONTINUE TO PUSH SOUTHWARD THROUGH THE AFTERNOON HOURS AND LOOKS TO HAVE A LITTLE THICKER STRATUS BEHIND IT. LATEST HRRR HAS CIGS FILLING BACK INTO CENTRAL IOWA PAST 20Z THIS AFTERNOON. OTHER CONCERN IS WITH MVFR/IFR VIS DUE TO LIGHT SNOW DEVELOPING LATER THIS AFTERNOON ALONG AND BEHIND THE FRONT. HAVE MENTION LOWER VIS AT MCW/FOD/ALO THIS AFTERNOON. MAY SEE LOWER VIS AT DSM/OTM BY THE EARLY EVENING BUT HAD LOW CONFIDENCE WITH MENTION AS NOT EXPECTING TO BE PERSISTENT. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...PODRAZIK LONG TERM...REV AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1143 AM CST THU FEB 14 2013 ....UPDATED FOR 18Z AVIATION DISCUSSION... .SHORT TERM /TODAY/... FIRST SHORTWAVE IS CURRENTLY SKIRTING THE NORTHEAST CORNER OF THE STATE THIS MORNING WITH FIRST PUSH OF SLIGHTLY COOLER AIR INTO THE STATE. HOWEVER...A SECOND SHORTWAVE WILL DROP SOUTHEAST THROUGH THE DAKOTAS AND INTO THE STATE BY THIS AFTERNOON. WEAK TO MODERATE FRONTOGENESIS WILL DROP INTO NORTH CENTRAL IOWA THIS AFTERNOON ASSOCIATED WITH THIS WAVE ALONG WITH WEAK ISENTROPIC LIFT. FAIRLY DEEP SATURATION AS WELL INDICATED IN THE BUFR SOUNDINGS AND LIGHT SNOW IS EXPECTED IN THE NORTH DURING THE AFTERNOON. FARTHER SOUTH...SOUNDINGS ARE WARMER AND IT APPEARS SOME THREAT OF RAIN AND SNOW EXISTS AND HAVE MAINTAINED SOME MIX WITH INITIAL ONSET OF ANY PCPN. SOUNDINGS MIX NICELY IN THE LOW LEVELS TODAY AND TEMPERATURES SHOULD WARM BEFORE THE BIGGER PUSH OF COLD AIR ARRIVES LATE TODAY INTO TONIGHT. AT THIS POINT...SNOW TOTALS IN THE NORTH WILL LIKELY BE AROUND AN INCH. .LONG TERM /TONIGHT THROUGH WEDNESDAY/... INITIALLY NORTHWEST TO NORTHERLY FLOW ALOFT REMAINS ACROSS THE REGION...WITH A WEAK SHORTWAVE SLIDING SOUTHEASTWARD THROUGH THE STATE TONIGHT. THIS WILL USHER IN ANOTHER PUSH OF COLD AIR...AND PROVIDE SUPPORT FOR SOME LIGHT SNOW ACROSS MUCH OF THE CWA THIS EVENING. EXPECT A BAND OF SNOW TO BE ORIENTED IN VICINITY OF THE HWY 20 CORRIDOR BY EARLY EVENING...WITH THE BAND MOVING OUT OF THE SOUTHERN CWA BY THE EARLY MORNING HOURS. ANY ACCUMULATIONS SHOULD REMAIN LIGHT WITH MOST SITES AROUND A HALF INCH OR LESS...WITH A FEW LOCATIONS POSSIBLY RECEIVING AS MUCH AS AN INCH. WITH THE CONTINUED PUSH OF COLD AIR INTO THE STATE...AND CYCLONIC FLOW ALOFT SCATTERED FLURRIES EXPECTED TONIGHT THROUGH FRIDAY NIGHT. ANOTHER WEAK IMPULSE ALSO SET TO DROP THROUGH THE CWA FRIDAY AFTERNOON. SOUNDINGS SHOWING LITTLE MOISTURE THOUGH...SO HAVE JUST STUCK WITH THE FLURRY MENTION WITH THIS WAVE. UPPER TROUGH TO FINALLY PUSH EAST OF THE REGION THIS WEEKEND...WITH UPPER LEVEL RIDGING BUILDING INTO THE CENTRAL US SATURDAY INTO SUNDAY. RETURN FLOW WILL SETUP ACROSS THE REGION LATE SATURDAY NIGHT INTO SUNDAY...WITH STRONG PUSH OF WAA SENDING H85 TEMPS INTO THE +4C RANGE. WITH SOUTH TO SOUTHWEST FLOW AT THE SURFACE AND ALOFT AND WITH MOSTLY SUNNY SKIES...SHOULD WARM UP NICELY SUNDAY. THEREFORE CONTINUED TO GO ABOVE GUIDANCE FOR TEMPS SUNDAY....PUSHING TEMPS INTO THE 40S/AROUND 50 ACROSS THE SOUTHWESTERN HALF OF THE CWA. AN UPPER LEVEL WAVE THEN DIGS INTO THE NORTHERN US...SLIDING THROUGH THE REGION BY MONDAY INTO MONDAY NIGHT. THE ASSOCIATED COLD FRONT WILL SWEEP ACROSS THE CWA MONDAY...WITH A CHANCE FOR SOME LIGHT RAIN EXPECTED TO DEVELOP IN VICINITY OF THE FRONT ACROSS THE SOUTHEASTERN CWA MONDAY. OTHERWISE REMAINDER OF CWA SHOULD REMAIN DRY...AS DEF ZONE PRECIP SHOULD SKIRT THE CWA TO THE NORTH/EAST. COULD SEE SOME FLURRIES ACROSS THE FAR NORTH...BUT FOR NOW HAVE LEFT DRY. OTHERWISE COLD AIR REMAINS IN PLACE THROUGH MUCH OF THE EXTENDED WITH HIGH PRESSURE AND DRY CONDITIONS EXPECTED FOR TUESDAY INTO EARLY WEDNESDAY. LONG RANGE MODELS STILL IN VERY GOOD AGREEMENT DIGGING A DEEP UPPER LEVEL TROUGH OVER THE INTERMOUNTAIN WEST BY MID WEEK...WITH THIS SYSTEM EXPECTED TO EJECT EASTWARD THROUGH THE REGION JUST BEYOND THE CURRENT FORECAST PERIOD TOWARD THURSDAY INTO FRIDAY. WITH MANY DETAILS REMAINING UNCERTAIN THIS FAR OUT...STILL LOOKS LIKE AN INCREASING LIKELIHOOD THAT A LARGE STORM SYSTEM COULD IMPACT THE AREA BY THE END OF NEXT WEEK. && .AVIATION...14/18Z INTERMITTENT MVFR STRATUS WILL PERSIST THROUGH THE AFTERNOON AND LOW CONFIDENCE WITH AN EXTENDED PERIOD OF MVFR STRATUS...BUT HIGH ENOUGH TO MENTION TIMING WITH A TEMPO. COLD FRONT DRAPED ACROSS NORTHERN IOWA WILL CONTINUE TO PUSH SOUTHWARD THROUGH THE AFTERNOON HOURS AND LOOKS TO HAVE A LITTLE THICKER STRATUS BEHIND IT. LATEST HRRR HAS CIGS FILLING BACK INTO CENTRAL IOWA PAST 20Z THIS AFTERNOON. OTHER CONCERN IS WITH MVFR/IFR VIS DUE TO LIGHT SNOW DEVELOPING LATER THIS AFTERNOON ALONG AND BEHIND THE FRONT. HAVE MENTION LOWER VIS AT MCW/FOD/ALO THIS AFTERNOON. MAY SEE LOWER VIS AT DSM/OTM BY THE EARLY EVENING BUT HAD LOW CONFIDENCE WITH MENTION AS NOT EXPECTING TO BE PERSISTENT. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...COGIL LONG TERM...BEERENDS AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS TOPEKA KS
531 PM CST FRI FEB 15 2013 ...UPDATE TO AVIATION... .DISCUSSION... 12Z UPPER AIR DATA DEPICTED AT 130KT JET DIVING SOUTH OUT OF WESTERN SASKATCHEWAN WITH WIDESPREAD 500MB TEMPS OF AROUND -40C OVER THE NORTHERN PLAINS AND EASTERN CANADA. AN UPPER LEVEL TROF WAS MAKING SOUTHWARD PROGRESS OUT OF THE WESTERN DAKOTAS IN RECENT HOURS PER WATER VAPOR IMAGERY. WEAK RADAR RETURNS HAVE DEVELOPED OVER MUCH OF NORTHERN KANSAS THOUGH DEWPOINT DEPRESSIONS AROUND 20F ARE LIKELY KEEP MUCH OF THIS WEAK ACTIVITY FROM REACHING THE GROUND. 20Z SURFACE-3KM LAPSE RATES NEAR 9C/KM WERE NOTED IN CENTRAL NEBRASKA...WITH AROUND 8C/KM VALUES EAST AND ALSO SOUTHEAST INTO THE LOCAL AREA. THE MAIN ISSUES TONIGHT ARE WHERE AND HOW LONG THE SNOW SHOWERS WILL LAST. THE VARIOUS GUIDANCE ALL POINTS TO A MORE SUSTAINED AREA OF PRECIPITATION SOMEWHERE IN NORTHEAST KANSAS...WITH THE DETAILS THE MAIN ISSUE. AS THE UPPER TROF CONTINUES SOUTH TO SOUTHEAST...THE LAPSE RATES REMAIN NEAR 8C/KM WELL INTO THE NIGHT AS FRONTOGENESIS AROUND 750MB INCREASES AND FOCUSES ON THE NORTHEAST TIP OF A DEVELOPING THETA-E RIDGE AT THIS LEVEL...RESULTING IN GOOD LIFT THROUGH THE DENDRITIC GROWTH ZONE. THE MOST RECENT HRRR AND RAP DATA HAS BEEN PUSHING THIS AREA NORTHEAST...FAVORING FAR NORTHEAST KANSAS MAINLY AROUND 03Z. HAVE INCREASED CHANCES AND AMOUNTS UP HERE...BUT STILL LIMITED MOISTURE AND THE COVERAGE OF ANY BANDS AND EXACTLY WHERE THIS WILL END UP KEEPS CHANCES BELOW LIKELY LEVELS. SOME BRIEF MODERATE SNOWFALLS CAN BE EXPECTED IN THE HEAVIEST PRECIPITATION... AND LOCAL AMOUNTS NEAR AN INCH SEEM PLAUSIBLE. ANY ACCUMULATING SNOW SHOULD END WELL BEFORE SUNRISE AS THE UPPER TROF SWINGS INTO THE MISSISSIPPI VALLEY. WESTERN AREAS SEE A QUICKLY DRYING TROPOSPHERE THIS EVENING...BUT HIGH CLOUD RETURNS THERE LATE TONIGHT AS WARM AIR ADVECTION ENSUES FROM THE UPPER PATTERN SHIFTING EAST. THOUGH INSOLATION WILL BE LIMITED AS THE CLOUDS DEEPEN SATURDAY...SOUTHWEST WINDS SHOULD SUPPORT TEMPS SEVERAL DEGREES ABOVE TODAYS LEVELS FOR CENTRAL AND WESTERN LOCATIONS. 65 SHORTWAVE RIDGING AND WARM AIR ADVECTION IS EXPECTED TO BRING WARMER TEMPS AND SUNNY SKIES TO THE AREA FOR SUNDAY. THEN THE NEXT SHORTWAVE IS EXPECTED TO MOVE ACROSS THE CENTRAL AND NORTHERN PLAINS BRINGING A COLD FRONT THROUGH THE AREA LATE SUNDAY NIGHT AND MONDAY MORNING. MODELS CONTINUE TO SHOW THE BETTER MOISTURE TO THE EAST OF THE FORECAST AREA. AND WITH THE FRONT PUSHING INTO MO BY THE LATE MORNING HOURS...PRECIP CHANCES SHOULD BE CONFINED TO FAR EASTERN KS DURING THE DAY MONDAY. TUESDAY AND WEDNESDAY LOOK TO BE IN BETWEEN SYSTEMS WITH SURFACE RIDGING BUILDING SOUTH THROUGH THE PLAINS. THIS SHOULD KEEP TEMPS FROM WARMING UP VERY MUCH. THE NEXT BIG WEATHER MAKER LOOKS TO IMPACT THE REGION WEDNESDAY NIGHT AND THURSDAY. BOTH THE GFS AND ECMWF HAVE TRENDED SLIGHTLY SLOWER WITH THE UPPER CLOSED LOW AS IT MOVES OUT OF THE SOUTHERN ROCKIES. HOWEVER THE GFS REMAINS SLIGHTLY FASTER THAN THE GFS. THE OTHER TREND OF NOTE IS THE ECMWF FURTHER NORTH WITH THE TRACK OF THE LOW PRESSURE SYSTEM. THIS COMPLICATES THE FORECAST OF PRECIP TYPE QUITE A BIT. INITIALLY WITH THE COLD SURFACE RIDGE IN PLACE WEDNESDAY...GFS FORECAST SOUNDINGS SUPPORT ALL SNOW WEDNESDAY EVENING. HOWEVER BOTH MODELS SHOW STRONG WARM AIR ADVECTION ALOFT AND A WARM NOSE DEVELOPING THROUGH THE NIGHT WITH SURFACE TEMPS REMAINING IN THE 20S AND LOWER 30S. AS THE WARM AIR ADVECTION DEVELOPS...FREEZING RAIN AND SLEET BECOME POSSIBLE WHILE SURFACE TEMPS ARE BELOW FREEZING. ON TOP OF THIS IS THE POTENTIAL FOR MID LEVEL DRY AIR TO WRAP UP IN THE SYSTEM AND FOR THE SOUNDINGS TO LOOSE SATURATION WITHIN THE DENDRITIC GROWTH LAYER ADDING TO THE POTENTIAL FOR FREEZING RAIN. REALLY THE TRACK OF THE SYSTEM DOES NOT FAVOR AN ALL SNOW EVENT FOR THE BULK OF THE FORECAST AREA. CONFIDENCE IN TRYING TO NAIL DOWN PRECIP TYPE IS VERY LOW AT THIS POINT GIVEN THAT IT IS 6 DAYS OUT...BUT THINK THAT THE PROBABILITY OF MIX WINTRY PRECIP IS HIGH ENOUGH THAT IT SHOULD BE MENTIONED IN THE FORECAST. ONE SHOULD NOT GET CAUGHT UP ON WHERE THE FORECAST HAS THE RAIN/SNOW LINE /WHICH IS LIKELY TO FLUCTUATE IN THE COMING DAYS/...BUT THAT THERE IS THE POTENTIAL FOR A MIXED BAG OF PRECIP. THINGS THAT COULD CHANGE THIS IS IF THE MAGNITUDE OF LOW LEVEL WARM AIR ADVECTION WERE TO INCREASE AND RAISE SURFACE TEMPS ABOVE FREEZING OR IF THE STORM SYSTEM TRENDS SOUTH AGAIN. IN ANY CASE IT LOOKS TO BE MESSY. WOLTERS && .AVIATION... EXPECT OCCASIONAL FLURRIES OVERNIGHT WITH SCATTERED SNOW SHOWERS THROUGH 6Z. THE HEAVIER SNOW SHOWERS MAY REDUCE VISIBILITIES DOWN TO 2 TO 3 SM AND CEILINGS MAY BRIEFLY DROP TO MVFR. AFTER 8Z THE SNOW SHOWERS AND FLURRIES WILL PUSH SOUTHEAST OF THE TAF SITES AND CEILINGS AND VISIBILITIES WILL REMAIN ABOVE VFR. GARGAN && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS JACKSON KY
1250 AM EST THU FEB 14 2013 .UPDATE... ISSUED AT 1250 AM EST THU FEB 14 2013 UPDATED THE FORECAST TO ADJUST THE CLOUD COVER FOR SOME ANTICIPATED LOW LEVEL STRATO CU. COVERAGE SHOULD SLOWLY SPREAD SPREAD WEST THROUGH THE NIGHT NIGHT BEFORE LIFTING AFTER 12Z. OTHERWISE THE FORECAST IS ON TRACK. UPDATE ISSUED AT 1006 PM EST WED FEB 13 2013 PRECIP SHOULD BE DONE FOR THE NIGHT AND IS REMOVED FROM THE 1ST PERIOD FORECAST. CLOUDS WILL BE TRICKY...BUT SHOULD GENERALLY BE MOST PREVALENT IN THE SE AND LEAST IN THE NW OVERNIGHT. UPDATE ISSUED AT 655 PM EST WED FEB 13 2013 HAVE UPDATED PRIMARILY FOR SKY COVER AND POPS IN THE FIRST PERIOD. CLEARING WAS ARRIVING FROM THE WEST EARLY THIS EVENING...AND BASED ON THE RUC AND NAM SHOULD PROGRESS SOUTHEAST TONIGHT. HOWEVER...THEY DO ALSO SUGGEST ANOTHER INCREASE IN CLOUDS FROM THE WEST BEFORE DAWN. THE ONLY RETURNS LEFT ON RADAR WERE IN THE FAR EASTERN PART OF THE AREA...WERE VERY LIGHT AND ON THE DECREASE. HAVE LOWERED POPS TO NOTHING MORE THAN 20 PERCENT OVER THE EASTERN TIP OF THE AREA...BUT DID ALLOW FOR SOME FLURRIES A BIT FURTHER WEST. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 231 PM EST WED FEB 13 2013 THE SFC LOW HAS PUSHED EAST INTO VA AND A SHORT PERIOD OF COLDER AIR IS CYCLING INTO THE AREA ON NW WINDS. MID LEVEL TROF RUNS FROM NEAR CLE TO CMH TO BNA AND WILL FOLLOW TO THE EAST LATER THIS AFTERNOON. WITH THE PASSAGE OF THE MID LEVEL TROF THIS EVENING THE PCPN SHOULD COME TO AN END AND RIDGING AT BOTH THE SFC AND MID LEVELS WILL BUILD INTO THE AREA. EXPECTING TEMPS TO FALL SLOWLY THE REST OF THIS AFTERNOON AND OVERNIGHT. CURRENT TEMPS IN THE MID 30S WILL BOTTOM OUT IN THE MORNING NEAR 30. THEN THE RIDGING WILL BRING A RETURN TO MLDER TEMPS THU AFTERNOON WITH HIGHS CLIMBING TO THE LOWER 50S. THE NEXT DISTURBANCE...CURRENTLY IN THE NRN PLAINS...WILL PUSH ACROSS THE WRN GREAT LAKES THU NIGHT BUT NOT IN TIME TO BRING MUCH COLDER TEMPS AS THE WINDS WILL SLOWLY RETURN TO THE WEST AND THEN SW TOWARDS FRI DAWN SO TEMPS WILL ONLY DROP TO THE LOWER 30S THU NIGHT...BUT UNDER PARTLY CLOUDY SKIES AND WITHOUT ANY PCPN. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 315 PM EST WED FEB 13 2013 A FAIRLY ACTIVE AND PROGRESSIVE WEATHER PATTERN WILL BE IN PLACE DURING THE LONG TERM PORTION OF THE FORECAST. A SERIES OF DISTURBANCES WILL CARVE OUT A DEEP TROF OVER THE EASTERN UNITED STATES FOR THE UPCOMING WEEKEND. AS COLDER AIR MOVES INTO THE AREA ON FRIDAY...MAY SEE SOME RAIN OR SNOW SHOWERS. WITH COLD AIR ADVECTION AND SOME UPSLOPE FLOW SNOW SHOWERS WILL ALSO BE POSSIBLE AT TIMES FROM FRIDAY NIGHT INTO SATURDAY NIGHT...MAINLY IN THE EASTERN PART OF THE FORECAST AREA. THE UPPER LEVEL TROF WILL QUICKLY MOVE EAST WITH WEAK RIDGING OVER THE OH VALLEY BY MONDAY. THIS WILL RESULT IN A QUICK WARM UP WITH TEMPERATURES RETURNING TO ABOVE NORMAL READINGS ON MONDAY AFTER WELL BELOW NORMAL TEMPERATURES OVER THE WEEKEND. AN APPROACHING COLD FRONT WILL BRING ANOTHER ROUND OF RAIN SHOWERS MONDAY NIGHT INTO TUESDAY. THERE COULD BE SOME LIGHT SNOW SHOWERS TUESDAY NIGHT AS COLDER AIR RETURNS ONCE AGAIN. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1250 AM EST THU FEB 14 2013 THE MAIN CONCERN FOR THE FIRST 6 HOURS OF THE TAF PERIOD IS SOME LOW LEVEL STRATO CU THAT IS EXPECTED TO DEVELOP OVER THE SOUTH AND EASTERN KENTUCKY. THE MVFR AND IFR CEILINGS WILL LIFT TO ABOUT 5 KFT AFTER 12Z. DURING THE DAY...WINDS UP TO 20 KNOTS OUT OF THE NORTHWEST WILL MIX TO THE SURFACE BEFORE TAPERING OFF BY 23Z. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SHALLENBERGER SHORT TERM...DUSTY LONG TERM...SBH AVIATION...SHALLENBERGER
AREA FORECAST DISCUSSION...UPDATED
NWS WAKEFIELD VA
434 PM EST THU FEB 14 2013 .SYNOPSIS... HIGH PRESSURE SLIDES OFF THE COAST TONIGHT AND A COLD FRONT APPROACHES THE MID ATLANTIC REGION ON FRIDAY. THE COLD FRONT WILL PASS THROUGH THE AREA FRIDAY NIGHT...FOLLOWED BY UNSETTLED CONDITIONS AND A COOLER CANADIAN AIRMASS FOR THE REMAINDER OF THE WEEKEND. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... HIGH PRESSURE SLIDES OFF THE COAST TONIGHT. AS THIS HAPPENS...A STEADY STREAM OF MID TO HIGH LEVEL CLOUDS OVER SE VA AND NE NC WILL GRADUALLY MOVE EWD WITH THE BACK EDGE OF THE RIDGE. EXPECT MOSTLY CLEAR SKIES AREAWIDE TONIGHT WITH LOWS IN THE 30S (NEAR 40 IMMEDIATE COAST). && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... FRIDAY AND FRIDAY NIGHT... FRIDAY WILL BE A DAY OF TRANSITION WITH HIGH PRESSURE OFF THE COAST AND A COLD FRONT APPROACHING FROM THE WEST. THE DAY WILL START OFF MOSTLY SUNNY BUT HIGH CLOUDS WILL MOVE INTO THE AREA FROM THE NORTHWEST DURING THE AFTN. THE COLD FRONT...WHICH EXTENDS FROM A LOW PRESSURE SYSTEM TRACKING ACROSS THE ST LAWRENCE RIVER VALLEY...WILL PASS THROUGH THE AREA FRIDAY NIGHT. PRECIP BEGINS AS ALL RAIN AND IS EXPECTED TO CHANGE OVER TO SNOW OR A RAIN/SNOW MIX AFTER MIDNIGHT AS COLD AIR INFILTRATES THE WRN HALF OF THE FA. EXPECT SNOW OVER FAR NW AREAS...AND A RAIN/SNOW MIX GENERALLY ALONG THE I-95 TRAVEL CORRIDOR BY EARLY SATURDAY MORNING. SATURDAY AND SATURDAY NIGHT... AN AREA OF LOW PRESSURE IS NOW PROGGED TO DEVELOP OFF THE NC COAST EARLY SATURDAY AND STAY JUST OFF THE MID ATLANTIC COAST DURING THE DAY. MEANWHILE SHORTWAVE ENERGY ROUNDING THE BASE OF THE DEEP UPPER LEVEL TROUGH...A STRONG JET STREAK MAXING OUT AROUND 150 KT... AND PLENTY OF COLD CANADIAN AIR ON THE BACK SIDE OF THE LOW WILL MAKE FOR AN INTERESTING FORECAST. THE NAM AND GFS MODELS ARE IN FAIR AGREEMENT WITH THE PLACEMENT OF THE DEVELOPING LOW PRESSURE CENTER (NAM IS A BIT FURTHER TO THE EAST BUT NOT BY MUCH) AND ALSO WITH GENERAL PLACEMENT OF QPF. THE GFS IS BULLISH WITH THE 6HR PRECIP AMTS AND THE NAM APPEARS TO BE TOO LIMITED WITH ITS QPF COVERAGE/AMTS DUE TO ITS CONVECTIVE PARAMETERIZATIONS. HIGHER QPF AMOUNTS ARE ANTICIPATED TO OCCUR GENERALLY ALONG AND NORTH OF I-64 INCLUDING THE MD/VA EASTERN SHORE. ALSO...A VERY TIGHT PRESSURE GRADIENT DEVELOPS DUE TO COLD AND DRY CANADIAN AIR TO THE NORTHWEST AND WARM/MOIST AIR TO THE SOUTHEAST. NORTHWEST WINDS WILL BECOME BREEZY...ESPECIALLY ALONG THE COAST. THE CLASH OF AIRMASSES SHOULD KEEP PERSISTENT WINTRY PRECIP OVER FAR NW AREAS THROUGH MOST OF THE DAY SATURDAY. HAVE INTRODUCED A COMBO OF SNOW AND SLEET (REALLY GRAUPEL AKA SNOW GRAINS) DURING THE DAY AS THE UPPER LEVEL TROUGH ENHANCES CONVECTIVE PRECIP AND WILL HELP DRIVE DOWN SNOW LEVELS AND WET BULB ZERO HEIGHTS. BY LATE AFTN/EARLY SATURDAY EVENING...WINTRY PRECIP IS EXPECTED TO SHIFT FURTHER TO THE SOUTHEAST AS A SNOW/GRAUPEL MIX WITH RAIN NEAR THE IMMEDIATE COAST. AS THE COASTAL LOW TRACKS TO THE NORTHEAST DURING THE EVENING AND TEMPERATURES BEGIN TO DROP... PRECIP SHOULD BECOME ALL SNOW BY LATE EVENING. STORM TOTAL SNOW ACCUMULATIONS AT THIS TIME RANGE FROM 0.6-1.6 INCHES NORTH OF A LINE FROM FVX-RIC-SBY...AND 0.5 INCHES OR LESS SOUTH OF THIS LINE. THE POTENTIAL FOR WINTRY CONDITIONS WILL BE COVERED IN THE HAZARDOUS WEATHER OUTLOOK AT THIS TIME. PRECIP IS EXPECTED TO QUICKLY SHUT OFF LATE SATURDAY EVENING ONCE THE LOW MOVES AWAY FROM THE MID ATLANTIC COAST. COLDER AIR WILL BE ABLE TO TAKE HOLD OF THE REGION SATURDAY NIGHT DESPITE DECENT MIXING PROVIDED BY NORTHWEST REMAINING ELEVATED OVERNIGHT. ANTICIPATE LOWS IN THE 20S. THE REGION WILL STAY UNDER THE INFLUENCE OF A BROAD UPPER LEVEL TROUGH THROUGH SUNDAY. COLDER AIR AND BREEZY WNW WINDS SHOULD PRODUCE WIND CHILLS IN THE UPPER TEENS TO LOWER 20S SUNDAY MORNING. EXPECT COOL HIGHS WITH TEMPS IN THE MID TO UPPER 30S (NEAR 40 IMMEDIATE COAST). && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... WILL LEAN TOWARD HPC GUIDANCE. THIS LEANS TOWARD A ECMWF ENSEMBLE SOLUTION. AFTER THE COLD FRONT AND LOW MOVE AWAY SUNDAY SHOULD BE A SUNNY COLD BREEZY DAY WITH TEMPERATURES BELOW NORMAL. IT SHOULD CONTINUE DRY THROUGH MONDAY WITH JUST A SLIGHT WARM UP ON MONDAY. THE FIRST SYSTEM TO IMPACT THE AREA WILL BE ON TUESDAY. BOTH GFS AND ECMWF ARE SIMILAR WITH THE MAIN LOW GOING UP TO THE WEST OF THE AREA AND PLENTY OF WARM AIR ARRIVING AHEAD OF THE PRECIPITATION SO WENT WITH MAINLY A RAIN EVENT. THE FRONT WILL AGAIN PUSH THROUGH ON TUESDAY NIGHT WITH PLENTY OF COLD AIR AND THERE COULD BE SOME MIX OR CHANGE TO SNOW SHOWERS AS THE FRONT PASSES. THE NEXT SYSTEM APPROACHES TOWARD THE END OF THE PERIOD. THE MODELS CONSENSUS WOULD KEEP IT MAINLY OUT OF THE AREA UNTIL FRIDAY SO KEPT IT DRY THROUGH THURSDAY. FOLLOWED ALONG CLOSE TO MOSGUIDE TEMPERATURES WHICH WERE ALSO CLOSE TO HPC. THIS KEEPS TEMPERATURES BELOW NORMAL FOR WEDNESDAY AND THURSDAY. && .AVIATION /22Z THURSDAY THROUGH TUESDAY/... LOOKING AT RAP SOUNDINGS CAN SEE ENOUGH MOISTURE IN THE BOUNDARY LAYER FOR SOME CLOUDS AND HAVE SEEN ESPECIALLY TOWARD THE COAST A BKN LAYER CLOSE TO 3000 FEET. THIS WILL SLOWLY LIFT AND DISSIPATE AS THE AFTERNOON GOES ON WITH MAINLY CLEAR SKIES BY EVENING. WINDS WILL BE VARIABLE AND LIGHT. CONTINUED VFR CONDITIONS TONIGHT AND FRIDAY. A STRONG COLD FRONT MOVES THROUGH THE AREA LATE FRIDAY NIGHT/EARLY SATURDAY MORNING. THERE IS A CHANCE OF RAIN AND/OR SNOW SHOWERS WITH THE FRONTAL PASSAGE ESPECIALLY FROM NW OF A LINE FROM RIC TO SBY AND THIS COULD LEAD TO MVFR OR IFR CONDITIONS FOR A TIME AS INTO SATURDAY AFTERNOON BEFORE VFR BUT BREEZY CONDITIONS RETURN FOR THE REST OF THE WEEKEND. && .MARINE... SFC HI PRES MOVES OVR THE WTRS FM THIS EVE THROUGH FRI MRNG. NEXT CDFNT APPROACHES FM THE W FRI AFTN/EVE...AND SLOWS AT IT REACHES THE CST SAT MRNG. MEANWHILE...WK SFC LO PRES BEGINS TO DVLP A FEW HUNDRED MI OFF THE NC/SC CST SAT MRNG. 12Z/14 NAM/GFS BOTH GRADUALLY INTENSIFY THE LO AS IT TRACKS NNE OFFSHR SAT INTO SAT NGT...(THE GFS MORE SO THAN THE NAM...AS WELL AS BEING CLOSER TO THE IMMEDIATE CST). CONTG W/ IDEA OF DELAY IN STRONGEST LO LVL CAA UNTIL SAT EVE THROUGH SUN...AS A RESULT OF THE STRENGTHENING SFC LO PRES TRACKING E OF CAPE COD...AND THE MID/UPR LVL TROUGH CROSSES THE MDATLC RGN. INCRSG CONFIDENCE FOR SOLID SCAS FM LT SAT THROUGH SUN...W/ (RIGHT NOW AT LEAST) A LO PROB FOR A PD OF GALES...ESP ON THE NRN OCN WTRS. LO LVL CAA RMNS THROUGH SUN NGT/ERY MON...BEFORE WANING DURG MON AS SFC HI PRES ARRIVES FM THE W/TROUGH ALOFT DEPARTS THROUGH THE CANADIAN MARITIMES (RESULTING IN LIGHTER WINDS/LWRG WAVES/SEAS). && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...BMD NEAR TERM...BMD SHORT TERM...BMD LONG TERM...JAB AVIATION...AJZ/JAB MARINE...ALB
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
423 PM EST THU FEB 14 2013 .SYNOPSIS... HIGH PRESSURE SLIDES OFF THE COAST TONIGHT AND A COLD FRONT APPROACHES THE MID ATLANTIC REGION ON FRIDAY. THE COLD FRONT WILL PASS THROUGH THE AREA FRIDAY NIGHT...FOLLOWED BY UNSETTLED CONDITIONS AND A COOLER CANADIAN AIRMASS FOR THE REMAINDER OF THE WEEKEND. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... HIGH PRESSURE SLIDES OFF THE COAST TONIGHT. AS THIS HAPPENS...A STEADY STREAM OF MID TO HIGH LEVEL CLOUDS OVER SE VA AND NE NC WILL GRADUALLY MOVE EWD WITH THE BACK EDGE OF THE RIDGE. EXPECT MOSTLY CLEAR SKIES AREAWIDE TONIGHT WITH LOWS IN THE 30S (NEAR 40 IMMEDIATE COAST). && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... FRIDAY AND FRIDAY NIGHT... FRIDAY WILL BE A DAY OF TRANSITION WITH HIGH PRESSURE OFF THE COAST AND A COLD FRONT APPROACHING FROM THE WEST. THE DAY WILL START OFF MOSTLY SUNNY BUT HIGH CLOUDS WILL MOVE INTO THE AREA FROM THE NORTHWEST DURING THE AFTN. THE COLD FRONT...WHICH EXTENDS FROM A LOW PRESSURE SYSTEM TRACKING ACROSS THE ST LAWRENCE RIVER VALLEY...WILL PASS THROUGH THE AREA FRIDAY NIGHT. PRECIP BEGINS AS ALL RAIN AND IS EXPECTED TO CHANGE OVER TO SNOW OR A RAIN/SNOW MIX AFTER MIDNIGHT AS COLD AIR INFILTRATES THE WRN HALF OF THE FA. EXPECT SNOW OVER FAR NW AREAS...AND A RAIN/SNOW MIX GENERALLY ALONG THE I-95 TRAVEL CORRIDOR BY EARLY SATURDAY MORNING. SATURDAY AND SATURDAY NIGHT... AN AREA OF LOW PRESSURE IS NOW PROGGED TO DEVELOP OFF THE NC COAST EARLY SATURDAY AND STAY JUST OFF THE MID ATLANTIC COAST DURING THE DAY. MEANWHILE SHORTWAVE ENERGY ROUNDING THE BASE OF THE DEEP UPPER LEVEL TROUGH...A STRONG JET STREAK MAXING OUT AROUND 150 KT... AND PLENTY OF COLD CANADIAN AIR ON THE BACK SIDE OF THE LOW WILL MAKE FOR AN INTERESTING FORECAST. THE NAM AND GFS MODELS ARE IN FAIR AGREEMENT WITH THE PLACEMENT OF THE DEVELOPING LOW PRESSURE CENTER (NAM IS A BIT FURTHER TO THE EAST BUT NOT BY MUCH) AND ALSO WITH GENERAL PLACEMENT OF QPF. THE GFS IS BULLISH WITH THE 6HR PRECIP AMTS AND THE NAM APPEARS TO BE TOO LIMITED WITH ITS QPF COVERAGE/AMTS DUE TO ITS CONVECTIVE PARAMETERIZATIONS. HIGHER QPF AMOUNTS ARE ANTICIPATED TO OCCUR GENERALLY ALONG AND NORTH OF I-64 INCLUDING THE MD/VA EASTERN SHORE. ALSO...A VERY TIGHT PRESSURE GRADIENT DEVELOPS DUE TO COLD AND DRY CANADIAN AIR TO THE NORTHWEST AND WARM/MOIST AIR TO THE SOUTHEAST. NORTHWEST WINDS WILL BECOME BREEZY...ESPECIALLY ALONG THE COAST. THE CLASH OF AIRMASSES SHOULD KEEP PERSISTENT WINTRY PRECIP OVER FAR NW AREAS THROUGH MOST OF THE DAY SATURDAY. HAVE INTRODUCED A COMBO OF SNOW AND SLEET (REALLY GRAUPEL AKA SNOW GRAINS) DURING THE DAY AS THE UPPER LEVEL TROUGH ENHANCES CONVECTIVE PRECIP AND WILL HELP DRIVE DOWN SNOW LEVELS AND WET BULB ZERO HEIGHTS. BY LATE AFTN/EARLY SATURDAY EVENING...WINTRY PRECIP IS EXPECTED TO SHIFT FURTHER TO THE SOUTHEAST AS A SNOW/GRAUPEL MIX WITH RAIN NEAR THE IMMEDIATE COAST. AS THE COASTAL LOW TRACKS TO THE NORTHEAST DURING THE EVENING AND TEMPERATURES BEGIN TO DROP... PRECIP SHOULD BECOME ALL SNOW BY LATE EVENING. STORM TOTAL SNOW ACCUMULATIONS AT THIS TIME RANGE FROM 0.6-1.6 INCHES NORTH OF A LINE FROM FVX-RIC-SBY...AND 0.5 INCHES OR LESS SOUTH OF THIS LINE. PRECIP IS EXPECTED TO QUICKLY SHUT OFF LATE SATURDAY EVENING ONCE THE LOW MOVES AWAY FROM THE MID ATLANTIC COAST. COLDER AIR WILL BE ABLE TO TAKE HOLD OF THE REGION SATURDAY NIGHT DESPITE DECENT MIXING PROVIDED BY NORTHWEST REMAINING ELEVATED OVERNIGHT. ANTICIPATE LOWS IN THE 20S. THE REGION WILL STAY UNDER THE INFLUENCE OF A BROAD UPPER LEVEL TROUGH THROUGH SUNDAY. COLDER AIR AND BREEZY WNW WINDS SHOULD PRODUCE WIND CHILLS IN THE UPPER TEENS TO LOWER 20S SUNDAY MORNING. EXPECT COOL HIGHS WITH TEMPS IN THE MID TO UPPER 30S (NEAR 40 IMMEDIATE COAST). && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... WILL LEAN TOWARD HPC GUIDANCE. THIS LEANS TOWARD A ECMWF ENSEMBLE SOLUTION. AFTER THE COLD FRONT AND LOW MOVE AWAY SUNDAY SHOULD BE A SUNNY COLD BREEZY DAY WITH TEMPERATURES BELOW NORMAL. IT SHOULD CONTINUE DRY THROUGH MONDAY WITH JUST A SLIGHT WARM UP ON MONDAY. THE FIRST SYSTEM TO IMPACT THE AREA WILL BE ON TUESDAY. BOTH GFS AND ECMWF ARE SIMILAR WITH THE MAIN LOW GOING UP TO THE WEST OF THE AREA AND PLENTY OF WARM AIR ARRIVING AHEAD OF THE PRECIPITATION SO WENT WITH MAINLY A RAIN EVENT. THE FRONT WILL AGAIN PUSH THROUGH ON TUESDAY NIGHT WITH PLENTY OF COLD AIR AND THERE COULD BE SOME MIX OR CHANGE TO SNOW SHOWERS AS THE FRONT PASSES. THE NEXT SYSTEM APPROACHES TOWARD THE END OF THE PERIOD. THE MODELS CONSENSUS WOULD KEEP IT MAINLY OUT OF THE AREA UNTIL FRIDAY SO KEPT IT DRY THROUGH THURSDAY. FOLLOWED ALONG CLOSE TO MOSGUIDE TEMPERATURES WHICH WERE ALSO CLOSE TO HPC. THIS KEEPS TEMPERATURES BELOW NORMAL FOR WEDNESDAY AND THURSDAY. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... LOOKING AT RAP SOUNDINGS CAN SEE ENOUGH MOISTURE IN THE BOUNDARY LAYER FOR SOME CLOUDS AND HAVE SEEN ESPECIALLY TOWARD THE COAST A BKN LAYER CLOSE TO 3000 FEET. THIS WILL SLOWLY LIFT AND DISSIPATE AS THE AFTERNOON GOES ON WITH MAINLY CLEAR SKIES BY EVENING. WINDS WILL BE VARIABLE AND LIGHT. CONTINUED VFR CONDITIONS TONIGHT AND FRIDAY. A STRONG COLD FRONT MOVES THROUGH THE AREA LATE FRIDAY NIGHT/EARLY SATURDAY MORNING. THERE IS A CHANCE OF RAIN AND/OR SNOW SHOWERS WITH THE FRONTAL PASSAGE ESPECIALLY FROM NW OF A LINE FROM RIC TO SBY AND THIS COULD LEAD TO MVFR OR IFR CONDITIONS FOR A TIME AS INTO SATURDAY AFTERNOON BEFORE VFR BUT BREEZY CONDITIONS RETURN FOR THE REST OF THE WEEKEND. && .MARINE... SFC HI PRES MOVES OVR THE WTRS FM THIS EVE THROUGH FRI MRNG. NEXT CDFNT APPROACHES FM THE W FRI AFTN/EVE...AND SLOWS AT IT REACHES THE CST SAT MRNG. MEANWHILE...WK SFC LO PRES BEGINS TO DVLP A FEW HUNDRED MI OFF THE NC/SC CST SAT MRNG. 12Z/14 NAM/GFS BOTH GRADUALLY INTENSIFY THE LO AS IT TRACKS NNE OFFSHR SAT INTO SAT NGT...(THE GFS MORE SO THAN THE NAM...AS WELL AS BEING CLOSER TO THE IMMEDIATE CST). CONTG W/ IDEA OF DELAY IN STRONGEST LO LVL CAA UNTIL SAT EVE THROUGH SUN...AS A RESULT OF THE STRENGTHENING SFC LO PRES TRACKING E OF CAPE COD...AND THE MID/UPR LVL TROUGH CROSSES THE MDATLC RGN. INCRSG CONFIDENCE FOR SOLID SCAS FM LT SAT THROUGH SUN...W/ (RIGHT NOW AT LEAST) A LO PROB FOR A PD OF GALES...ESP ON THE NRN OCN WTRS. LO LVL CAA RMNS THROUGH SUN NGT/ERY MON...BEFORE WANING DURG MON AS SFC HI PRES ARRIVES FM THE W/TROUGH ALOFT DEPARTS THROUGH THE CANADIAN MARITIMES (RESULTING IN LIGHTER WINDS/LWRG WAVES/SEAS). && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...BMD NEAR TERM...BMD SHORT TERM...BMD LONG TERM...JAB AVIATION...AJZ/JAB MARINE...ALB
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1247 PM EST THU FEB 14 2013 .SYNOPSIS... HIGH PRESSURE RETURNS TODAY IN WAKE OF DEPARTING LOW PRESSURE. A COLD FRONT PASSES THROUGH THE REGION LATE FRIDAY...FOLLOWED BY UNSETTLED CONDITIONS AND A COOLER CANADIAN AIRMASS FOR THE REMAINDER OF THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... LATEST WATER VAPOR IMAGERY SHOWS SEVERAL SHORTWAVES EMBEDDED IN BROAD UPPER LEVEL TROUGH OVER THE CNTRL/ERN CONUS THIS MORNING. SHORTWAVE/ENERGY RESPONSIBLE FOR PRECIP YESTERDAY HAS PUSHED OFF THE NE COAST. ALSO VISIBLE IS SRN STREAM MOISTURE BEING SHUNTED TO THE SOUTH OF THE REGION ALLOWING FOR DRYING CONDITIONS OVER THE MID ATLANTIC. AT THE SFC...LOW PRESSURE HAS LIFTED WELL OFF THE COAST AS HIGH PRESSURE BUILDS INTO THE SOUTHEAST. AFOREMENTIONED DRY AIR AND HIGH PRESSURE WILL RESULT IN CLEARING SKIES TODAY. HOWEVER...LOW STRATUS WILL PERSIST THROUGH MID MORNING...POSSIBLE LATER ACROSS THE ERN SHORE. CALM WINDS...CLEARING SKIES AND RESIDUAL LOW LEVEL MOISTURE WILL RESULT IN PATCHY FOG ACROSS THE PIEDMONT THROUGH MID MORNING. OTHERWISE...SFC HIGH PRESSURE WILL CONTINUE TO BUILD OVER THE SOUTHEAST TODAY...EXTENDING NEWD INTO THE MID ATLANTIC. LACK OF STRONG CAA WILL ALLOW MODEST RECOVERS IN LOW LEVEL THICKNESS VALUES...RESULTING IN SLIGHTLY ABOVE NORMAL DAYTIME TEMPS (LOW/MID 50S). MEANWHILE...A SHORTWAVE AND ASSOCIATED SFC LOW WILL LIFT OVER THE GREAT LAKES TONIGHT. A WEAK COLD FRONT WILL LOCATE OVER WRN VA AS AN ARCTIC FRONT REACHES THE OH VALLEY BY EARLY FRIDAY MORNING. WILL BEGIN TO SEE INCREASING CLOUDS ACROSS THE NW FA EARLY FRIDAY MORNING. TEMPS WILL DROP INTO THE LOW 30S NW TO NEAR 40 SE UNDER CLEAR/MOSTLY CLEAR SKIES AND LIGHT WINDS. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... ADDITIONAL ENERGY WILL DIVE INTO THE UPPER MIDWEST AIDED BY A 140+ KT JET STREAK...HELPING DEEPEN THE UPPER TROUGH ACROSS THE ERN CONUS. AFOREMENTIONED GREAT LAKES LOW WILL LIFT WELL TO THE NE AS THE ARCTIC COLD FRONT LOCATES OVER THE OH/TN VALLEYS FRIDAY AFTERNOON. THEREAFTER...TIMING AND SPATIAL DIFFERENCES IN LATEST MODEL GUIDANCE WILL RESULT IN A BELOW CONFIDENCE FORECAST BEGINNING FRIDAY NIGHT WITH FRONTAL PASSAGE AND CYCLOGENESIS ALONG THE MID ATLANTIC COAST. TRENDED FORECAST TOWARD A GFS/ECMWF BLEND AS NAM GUIDANCE SEEMS UNREALISTIC WITH DEVELOPING A SFC LOW TOO FAR INLAND. THUS...COLD FRONT IS FORECAST TO CROSS THE REGION LATE FRIDAY AS A BROAD LONGWAVE TROUGH SETTLES OVER THE ERN CONUS. WAVE OF LOW PRESSURE WILL LIFT ALONG A COASTAL BOUNDARY FRIDAY NIGHT...DEVELOPING INTO A COASTAL LOW OFF THE MID ATLANTIC COAST SATURDAY MORNING AS A STRONG PV ANOMALY AND THE DEEP UPPER TROUGH APPROACH. STRONG FRONTOGENETIC FORCING ALONG THE ARCTIC FRONT WILL LOCATE OVER THE NW FA LATE FRIDAY NIGHT. MOISTURE WILL BE SOMEWHAT LIMITED WITH PRECIP WATERS AOB HALF AN INCH. HOWEVER...HIGH MODEL RH AND OMEGA AT -10C AS WELL AS GOOD DYNAMICS (PROVIDED BY SHORTWAVE AND LOW LEVEL FRONTOGENETIC FORCING) WILL BE ENOUGH FOR PRECIP ACROSS FA THROUGH SATURDAY MORNING. HAVE INTRODUCED CHANCE POPS ACROSS THE PIEDMONT THROUGH THE NRN FA AND THE ERN SHORE SATURDAY MORNING. MAIN FORECAST CHALLENGE WILL BE TIMING OF COLD CANADIAN AIR LATE FRIDAY NIGHT/EARLY SATURDAY MORNING. TEMPERATURE PROFILES SUGGEST ACCUMULATING SNOW OVER MUCH OF THE PIEDMONT EARLY SATURDAY MORNING AND OVER THE NRN FA BY SUNRISE. TEMPS WILL WARM ABOVE FREEZING SHORTLY AFTER SUNRISE TO CHANGE ALL PRECIP OVER TO RAIN. HAVE PLACED LIGHT ACCUMULATIONS (LESS THAN HALF AN INCH) OVER PORTIONS OF THE PIEDMONT SATURDAY MORNING. WILL LIKELY HAVE TO ADD ADDITIONAL LIGHT ACCUMULATIONS FURTHER EAST AND NORTH...BUT WILL WAIT FOR BETTER MODEL CONSENSUS. TEMPS FRIDAY AFTERNOON WILL RANGE FROM THE MID/UPPER 50S TO NEAR 60 ALONG THE COAST...SO GROUND TEMPS WILL LIMIT AMOUNT OF ACCUMULATIONS. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... FOLLOWING HPC GUIDANCE FOR MOST OF THE PERIOD. THE ECMWF AND GFS NOW SIMILAR WITH FRONT COMING THROUGH SATURDAY NIGHT. THERE IS NOW MORE CONSENSUS IN NOT PHASING THE UPPER SYSTEM UNTIL IT IS OFFSHORE WHICH SHOULD KEEP THE DEVELOPMENT AWAY FROM OUR AREA. COULD STILL HAVE SOME LIGHT PRECIPITATION WITH THE STRONG FRONT AS IT MOVES ACROSS THE AREA SATURDAY NIGHT. LOOKING AT TEMPERATURE PROFILES...IT IS POSSIBLE THAT SOME SNOW COULD MIX WITH THE RAIN SHOWERS AS IT PASSES THROUGH. NOT EXPECTING MANY SHOWERS AND ALL PRECIPITATION SHOULD BE LIGHT. BY SUNDAY HIGH PRESSURE IS BUILDING OVER THE AREA AND TEMPERATURES WILL PLUNGE WITH HIGHS MAINLY AROUND 40. FOLLOWED HPC AND MOSGUIDE FOR TEMPERATURES AS THEY ARE SIMILAR. NEXT UPPER TROF BEGINS TO APPROACH ON TUESDAY AND PUSHES ANOTHER FRONT ACROSS THE AREA TUESDAY AND TUESDAY NIGHT. THERE WILL BE ENOUGH WARM UP AHEAD OF THIS FRONT THAT ALL PRECIPITATION SHOULD BE RAIN. HIGH TEMPERATURES WILL BE BACK INTO THE 50S. ANOTHER COOL DOWN TO SLIGHTLY BELOW NORMAL TEMPERATURES WILL OCCUR ON WEDNESDAY. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... LOOKING AT RAP SOUNDINGS CAN SEE ENOUGH MOISTURE IN THE BOUNDARY LAYER FOR SOME CLOUDS AND HAVE SEEN ESPECIALLY TOWARD THE COAST A BKN LAYER CLOSE TO 3000 FEET. THIS WILL SLOWLY LIFT AND DISSIPATE AS THE AFTERNOON GOES ON WITH MAINLY CLEAR SKIES BY EVENING. WINDS WILL BE VARIABLE AND LIGHT. CONTINUED VFR CONDITIONS TONIGHT AND FRIDAY. A STRONG COLD FRONT MOVES THROUGH THE AREA LATE FRIDAY NIGHT/EARLY SATURDAY MORNING. THERE IS A CHANCE OF RAIN AND/OR SNOW SHOWERS WITH THE FRONTAL PASSAGE ESPECIALLY FROM NW OF A LINE FROM RIC TO SBY AND THIS COULD LEAD TO MVFR OR IFR CONDITIONS FOR A TIME AS INTO SATURDAY AFTERNOON BEFORE VFR BUT BREEZY CONDITIONS RETURN FOR THE REST OF THE WEEKEND. && .MARINE... ALL SCA FLAGS ARE NOW EXPIRED. HIGH PRESSURE BUILDS ACROSS THE AREA TODAY AND REMAINS OFF THE SOUTHEAST COAST THROUGH FRIDAY. LOW PRESSURE TRACKS N OF THE SAINT LAWRENCE VALLEY THURSDAY NIGHT AND FRIDAY DRAGGING A STRONG COLD FRONT TOWARD THE REGION FRIDAY AFTERNOON...AND ACROSS THE MID ATLANTIC COAST LATE FRIDAY NIGHT INTO SATURDAY MORNING. SECONDARY LOW PRESSURE DEVELOPMENT IS EXPECTED ALONG THE BOUNDARY AS IT CROSSES THE AREA AND THIS WILL DELAY THE STRONGEST CAA UNTIL LATER SATURDAY. INCREASED WIND SPEEDS (TO SCA OUT OF THE NW) ARE EXPECTED ALONG WITH BUILDING WAVES/SEAS SATURDAY NIGHT INTO SUNDAY. SURFACE HIGH PRESSURE RETURNS MONDAY RESULTING IN LIGHTER WIND AND SUBSIDING WAVES/SEAS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...SAM/TMG NEAR TERM...SAM SHORT TERM...SAM LONG TERM...JAB AVIATION...AJZ/JAB MARINE...AJZ
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1228 PM EST THU FEB 14 2013 .SYNOPSIS... FAST MOVING LOW PRESSURE WILL MOVE ACROSS THE GREAT LAKES TODAY BRINGING A CHANCE OF RAIN SHOWERS EARLY AND SNOW SHOWERS OVERNIGHT AS A WEAK FRONT CROSSES. COLDER AIR BEHIND THE FRONT WILL PROVIDE THE RISK FOR SNOW SHOWERS INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... NOT MUCH MORE THAN FEW FLURRIES ARE BEING OBSERVED THIS MORNING OUT AHEAD OF THE LOW PRESSURE SYSTEM CURRENTLY ANALYZED OVER MICHIGAN. THE RUC SEEMS TO BE PICKING UP ON THESE FLURRIES WITH MID LEVEL CLOUD DECK RIGHT AROUND THE LOWER END OF THE DENDRITIC GROWTH ZONE HELPING TO SEED THE LOWER LEVEL STRATUS. THIS SHOULD END SHORTLY AS WARM ADVECTION AND MIXING OUT AHEAD OF THE LOW HELPS TO WARM TEMPERATURES ABOVE FREEZING. WITH MID-DECK REMAINING IN PLACE HOWEVER...DIDN`T GO OVER ZEALOUS WITH THE WARMING TODAY AND TEMPERATURES WERE KEPT CLOSE TO MET GUIDANCE. WITH VERY LITTLE MOISTURE FOR THIS CLIPPER-LOW TO WORK WITH AS IS APPARENT IN BOTH SATELLITE DATA AND THE MODEL RUNS...MAINTAINED HIGHER CHANCE POPS FOR MUCH OF THE NORTHERN HALF OF THE REGION TODAY...CLOSER TO THE LOW CENTER WHERE BETTER LIFT IS PRESENT. PRECIPITATION SHOULD MAINLY START OUT AS RAIN THROUGH EARLY THIS EVENING AHEAD OF THE LAGGING COLD FRONT THAT SHOULD CROSS OVERNIGHT. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... WEAK COLD ADVECTION RETURNS THURSDAY NIGHT INTO FRIDAY AS A STRONG COLD FRONT PUSHES ACROSS THE REGION. TEMPERATURES WILL FALL WELL BELOW NORMAL BY FRIDAY NIGHT AND CONTINUE QUITE COLD INTO SATURDAY AS 850MB TEMPS FALL TO -18C. EXPECT SCATTERED SNOW SHOWERS THROUGH THE PERIOD. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... PROGRESSIVE PTN IS INDICATED THROUGH THE LONG TERM PD WITH SHSN DIMINISHING SATURDAY NGT INTO SUNDAY. WARM ADVCTN REGIME IS EXPECTED TO MODERATE TEMPS BACK TOWARD THE AVERAGES AND ABOVE BY MONDAY AS THE NXT UPR LVL TROF DVLPS EWD. THAT SYSTEMS CDFNT IS PROJECTED ACRS THE REGION BY TUESDAY NGT. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... ALTHOUGH HIGH PRESSURE RIDGE IS MOVING INTO THE REGION...IFR STRATUS REMAINS DRAPED ACROSS THE PORTS THIS AFTERNOON. LOW LEVEL MOISTURE IS TRAPPED AT THE SURFACE...BUT SOME HEATING THIS AFTERNOON SHOULD BRING CEILINGS BACK ABOVE 1000 FEET. A RAPIDLY MOVING COLD FRONT PUSHING ACROSS THE GREAT LAKES TONIGHT WILL SHIFT WINDS FROM THE SOUTH TO THE WEST AND PROVIDE A FEW GUSTS TO 20 KNOTS OVERNIGHT. THE MVFR STRATOCU WITH AND BEHIND THE FRONT WILL PERSIST INTO FRIDAY. LITTLE PRECIPITATION IS EXPECTED WITH THE FRONT BUT HAVE INCLUDED SOME FLURRIES AT THE NORTHERN PORTS. .OUTLOOK.../FRIDAY THROUGH MONDAY/... PERIODIC RESTRICTIONS ARE PSBL THRU SUN AS SVRL FAST MOVG DISTURBANCES MOVE THRU THE GT LKS RGN. HI PRES AND VFR CONDS RETURN MON. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1044 AM EST THU FEB 14 2013 .SYNOPSIS... FAST MOVING LOW PRESSURE WILL MOVE ACROSS THE GREAT LAKES TODAY BRINGING A CHANCE OF RAIN SHOWERS EARLY AND SNOW SHOWERS OVERNIGHT AS A WEAK FRONT CROSSES. COLDER AIR BEHIND THE FRONT WILL PROVIDE THE RISK FOR SNOW SHOWERS INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... NOT MUCH MORE THAN FEW FLURRIES ARE BEING OBSERVED THIS MORNING OUT AHEAD OF THE LOW PRESSURE SYSTEM CURRENTLY ANALYZED OVER MICHIGAN. THE RUC SEEMS TO BE PICKING UP ON THESE FLURRIES WITH MID LEVEL CLOUD DECK RIGHT AROUND THE LOWER END OF THE DENDRITIC GROWTH ZONE HELPING TO SEED THE LOWER LEVEL STRATUS. THIS SHOULD END SHORTLY AS WARM ADVECTION AND MIXING OUT AHEAD OF THE LOW HELPS TO WARM TEMPERATURES ABOVE FREEZING. WITH MID-DECK REMAINING IN PLACE HOWEVER...DIDN`T GO OVER ZEALOUS WITH THE WARMING TODAY AND TEMPERATURES WERE KEPT CLOSE TO MET GUIDANCE. WITH VERY LITTLE MOISTURE FOR THIS CLIPPER-LOW TO WORK WITH AS IS APPARENT IN BOTH SATELLITE DATA AND THE MODEL RUNS...MAINTAINED HIGHER CHANCE POPS FOR MUCH OF THE NORTHERN HALF OF THE REGION TODAY...CLOSER TO THE LOW CENTER WHERE BETTER LIFT IS PRESENT. PRECIPITATION SHOULD MAINLY START OUT AS RAIN THROUGH EARLY THIS EVENING AHEAD OF THE LAGGING COLD FRONT THAT SHOULD CROSS OVERNIGHT. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... WEAK COLD ADVECTION RETURNS THURSDAY NIGHT INTO FRIDAY AS A STRONG COLD FRONT PUSHES ACROSS THE REGION. TEMPERATURES WILL FALL WELL BELOW NORMAL BY FRIDAY NIGHT AND CONTINUE QUITE COLD INTO SATURDAY AS 850MB TEMPS FALL TO -18C. EXPECT SCATTERED SNOW SHOWERS THROUGH THE PERIOD. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... PROGRESSIVE PTN IS INDICATED THROUGH THE LONG TERM PD WITH SHSN DIMINISHING SATURDAY NGT INTO SUNDAY. WARM ADVCTN REGIME IS EXPECTED TO MODERATE TEMPS BACK TOWARD THE AVERAGES AND ABOVE BY MONDAY AS THE NXT UPR LVL TROF DVLPS EWD. THAT SYSTEMS CDFNT IS PROJECTED ACRS THE REGION BY TUESDAY NGT. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... ALTHOUGH HIGH PRESSURE RIDGE IS MOVING INTO THE REGION...MVFR STRATUS REMAINS DRAPED FROM PITTSBURGH TO THE SOUTH. LOW LEVEL MOISTURE APPEARS TO BE TRAPPED AT THE SURFACE. EXPECT THAT MVFR CONDITIONS WILL CONTINUE AT MOST SITES...WITH MOST LOCATIONS KEEPING THE STRATUS DECK...WITH FOG REDEVELOPING IN LOCATIONS AS STRATUS SLOWLY MOVES TO THE EAST OVERNIGHT. EXPECT STRATOCUMULUS TO DEVELOP ACROSS THE AREA THURSDAY. HAVE STUCK WITH VFR CIGS IN TAFS FOR NOW...ALTHOUGH MODEL PROFILES SHOW THAT CIGS MAY ACTUALLY DEVELOP AS HIGH MVFR INSTEAD. MOST LOCATIONS SHOULD HAVE S-SW GUSTS TO 15-20 KTS DURING THE AFTERNOON HOURS. STILL DO NOT HAVE ENOUGH CONFIDENCE IN PRECIPITATION CHANCES AT FKL/DUJ TO INCLUDE IN TAFS AT THIS TIME...ALTHOUGH THIS EVENING WOULD HAVE THE GREATEST LIKELIHOOD FOR SNOW SHOWERS. .OUTLOOK.../FRIDAY THROUGH MONDAY/... PERIODIC RESTRICTIONS ARE PSBL THRU SUN AS SVRL FAST MOVG DISTURBANCES MOVE THRU THE GT LKS RGN. HI PRES AND VFR CONDS RETURN MON. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
359 PM EST THU FEB 14 2013 .SHORT TERM...THIS EVENING AND TONIGHT THE VORTICITY RICH POTENTIAL VORTICITY ANOMALY NOW SPINNING ACROSS CENTRAL LAKE MICHIGAN HAS LED TO A NUMBER OF SPOKES/BANDS OF PRECIPITATION SLIDING THROUGH LOWER MICHIGAN. SINCE MIDDAY THESE BANDS HAVE BEEN NOTHING MORE THAN LIGHT RAIN SHOWERS OR SPRINKLES PER SFC REPORTS AND A NEAR SURFACE MELTING LAYER AT GREATER THAN 4C. VARIOUS HIRES MODELS ARE SUGGESTING THAT CONVECTION/SHOWER DEVELOPMENT WILL TAKE PLACE ALONG AND AHEAD OF THE COLD FRONT BETWEEN 21-00Z. THIS IDEA REMAINS VALID. DIFFICULT TO EVALUATE THE OVERALL THERMODYNAMIC PROFILE OR HOW MUCH CAPE IS OUT THERE WITH THE VALID RUC BASED SPC MESOANALYSIS GRAPHIC SHOWING NOTHING IN THE WAY OF MUCAPE. GOING THROUGH MODEL DATA THOUGH SUGGESTS THAT 50 TO 100 J/KG IS PLAUSIBLE GIVEN SFC/DWPT VALUES THAT ARE ON TARGET. EVOLUTION OF MODEL SOUNDINGS SUGGESTS THAT IT WILL REQUIRE SOME COOLING FROM APPROACHING COLD FRONT TO ERODE A LOW CAPPING LAYER TO ALLOW FOR INITIATION. THE POTENTIAL EXISTS FOR CONVECTION TO YIELD GRAUPEL/ICE PELLETS. ADDITIONALLY...THERE REMAINS A POSSIBILITY THAT BURSTS COULD PRODUCE MORE IN THE WAY OF SNOW...AND THE PERCENTAGE OF OCCURRENCE IS AN UNKNOWN. FARTHER NORTH...EXPECTING THE ACTIVITY TO FALL AS RAIN...ALTHOUGH THIS AREAS STANDS A BETTER CHANCE TO SEE SOME LIGHT SNOW WITH MINOR ACCUMULATIONS. WINDS WILL INCREASE...UP TO 25 TO 30 MPH...AS WIND DIRECTIONS SHIFT FROM 200 TO 240 POST COLD FRONT. ISENTROPIC DOWNGLIDE WILL COMMENCE BETWEEN 00-03Z...KICKING IT UP A COUPLE OF GEARS BETWEEN 03-09Z. THE COLUMN IS SHOWN TO BECOME QUITE STABLE IN THE 900-700MB LAYER...TOO STABLE TO SUPPORT MUCH IN THE WAY OF SNOW TONIGHT. NAM IS HIGHLIGHTING SOME LAKE EFFECT BANDING/ENHANCED CONVERGENCE ACROSS SW LOWER LATE TONIGHT. DID LEAVE A LOW CHANCE FOR LIGHT IN ACROSS THE SOUTH AS THERE IS SOME POTENTIAL FOR SOME SNOWFLAKES TO MAKE THE TRIP ACROSS THE PENINSULA. OTHERWISE...FLURRIES FOR A MAJORITY OF THE AREA. LOWS TONIGHT WERE DERIVED FROM A BLEND OF RAW MODEL OUTPUT...A DECENT ADJUSTMENT DOWNWARD UPPER TEENS NORTH TO UPPER 20S SOUTH. && .LONG TERM...FRIDAY THROUGH NEXT THURSDAY LONGWAVE TROUGH WILL LOCK COOL AIR IN PLACE OVER THE GREAT LAKES THROUGH THE WEEKEND...AS H850 TEMPS DROP TO AROUND -18C (BY SAT NIGHT) IN THE POST-FRONTAL AIRMASS. CHANCES FOR ACCUMULATING SNOW LOOK FAIRLY LOW FOR THIS SIDE OF THE STATE...AND WILL BE DUE TO A COMBINATION OF WEAK SHORTWAVES AND LAKE EFFECT. SHORTWAVES MAY BE A LITTLE HARD TO TIME DUE TO SMALL NATURE AND LACK OF SAMPLING (AT THIS TIME) AND FORECAST ADJUSTMENTS ARE STILL POSSIBLE AS CHANGES IN TIMING/LOCATION OF SHORTWAVES IMPACT LAKE EFFECT PARAMETERS SUCH AS STABILITY...MOISTURE...AND WIND SPEED AND TRAJECTORY. MODEL GUIDANCE TAKES THE WAVE NOW DROPPING THROUGH SOUTHERN MANITOBA ACROSS NORTHERN LOWER MICHIGAN TOMORROW...WHILE ALSO SHEARING APART ANOTHER SHORTWAVE AS IT DROPS FROM THE DAKOTAS DOWN INTO THE OHIO VALLEY. VERY WEAK LIFT ASSOCIATED WITH THESE WAVES COULD PROVIDE A BRIEF SNOW SHOWER TO THE AREA...BUT MAINLY EXPECT A LOT OF CLOUDS AND FLURRIES AROUND DUE TO LAKE EFFECT AND STEEP LAPSE RATES. DID KEEP LOW POPS IN THE FORECAST...BUT THINK FAIRLY WEAK FLOW OVER THE LAKE AND ONLY MODERATE INSTABILITY SHOULD KEEP ACCUMULATIONS TO OUR WEST. SIMILAR POP FORECAST EXISTS ON FRIDAY NIGHT. ALTHOUGH MOISTURE DEPTH AND COLD AIR ADVECTION WILL INCREASE...MEAN SURFACE-850MB FLOW ACROSS LAKE MICHIGAN WILL ONLY RUN 10-15 KNOTS...AND WILL TURN A LITTLE MORE TO THE NORTHWEST. AGAIN WOULD EXPECT MOSTLY FLURRIES...AND ONLY LOW CHANCES FOR LIGHT ACCUMULATIONS SOUTH OF A LINE FROM HOWELL TO DETROIT. POTENTIAL FOR LIGHT SNOW LOOKS A LITTLE BETTER ON SATURDAY AS A SHORTWAVE TROUGH AXIS CLIPS ACROSS THE AREA. LAKE EFFECT ENHANCEMENT ALSO LOOKS MORE LIKELY AS EQUILIBRIUM HEIGHTS OVER LAKE MICHIGAN HIT THEIR PEAK AROUND 12KFT AND LAKE TO H850 DELTA T VALUES RISE TO OVER 20 C. LIMITING FACTORS FOR THIS SIDE OF THE STATE ONCE AGAIN WILL BE LIGHT FLOW AND WINDS TURNING MORE TO THE NORTH-NORTHWEST. WOULD EXPECT FLURRIES AND SCATTERED LIGHT SNOW SHOWERS ACROSS THE AREA IN THIS SET-UP...WITH BETTER POTENTIAL (HIGHER POPS) SOUTH OF M-59 WHERE CONVERGENCE SHOULD BE BETTER. LONGWAVE TROUGH WILL PUSH TO THE EAST COAST DURING THE SECOND HALF OF THE WEEKEND...ALLOWING AN UPSTREAM RIDGE TO SLIDE IN OVERHEAD SUNDAY INTO MONDAY. ENERGY DIVING OUT OF THE GULF OF ALASKA WILL DROP THROUGH THE CENTRAL ROCKIES MONDAY...PULLING ADDITIONAL ENERGY OUT OF THE SOUTHERN STREAM BEFORE IT BECOMES MORE ORGANIZED AND DEEPENS OVER THE GREAT LAKES MONDAY NIGHT AND TUESDAY (AIDED BY GOOD HEIGHT FALLS AND STRONG JET DYNAMICS). TRENDS WITH THE EURO AND GFS HAVE BEEN TO SHIFT THIS SYSTEM FURTHER NORTH OVER THE PAST 24 HOURS...WITH A SURFACE LOW CENTER TRACK MORE ACROSS CENTRAL OR NORTHERN MICHIGAN. GIVEN THAT THE GEM AND UKMET ARE STILL FURTHER SOUTH WITH THE TRACK...MADE JUST MINOR ADJUSTMENTS TO PRECIPITATION TYPE THIS FORECAST CYCLE TO INCREASE RAIN POTENTIAL. 14.12Z EURO/GFS SOLUTIONS NOW SUPPORT ALL RAIN MONDAY NIGHT BEFORE A CHANGEOVER TO SNOW BEHIND A STRONG COLD FRONT ON TUESDAY. ACCUMULATIONS STILL LOOK POSSIBLE...BUT MAY BE DELAYED UNTIL TUESDAY. && .MARINE... LOW PRESSURE WILL TRACK THROUGH LOWER MICHIGAN THIS AFTERNOON AND ACROSS NORTHERN LAKE HURON THIS EVENING. CURRENT SURFACE OBSERVATIONS IN THE INCREASED GRADIENT PORTION OF THE SURFACE LOW IS SUPPORTING WIND GUSTS OF UP TO 30 KNOTS. WITH NO EXPECTED DEEPENING/ACTUAL MIDLEVEL WEAKENING RATES WILL CANCEL THE GALE WATCH AND FORGO A GALE WARNING. THIS IS ALSO SUPPORTED BY THE VERY BRIEF DURATION TIME. HOWEVER...WITH THE COLD NORTHWEST FLOW FOLLOWING THE CYCLONE...DID ISSUE A BRISK WIND ADVISORY FOR ALL NEARSHORE ZONES. WINDS WILL WEAKEN ON FRIDAY AS ARCTIC HIGH PRESSURE BUILDS INTO THE WESTERN GREAT LAKES REGION. THIS HIGH WILL KEEP RELATIVELY LIGHT WINDS ON THE LAKES THROUGH THE WEEKEND. A LOW PRESSURE SYSTEM IS FORECAST TO INTENSIFY OVER THE GREAT LAKES REGION MONDAY NIGHT INTO TUESDAY AND WILL OFFER THE NEXT CHANCE FOR STRONG WINDS. && .AVIATION...ISSUED 104 PM EST THU FEB 14 2013 //DISCUSSION... THE CLOSED MIDLEVEL LOW CIRCULATION NOW ROUNDING INTO MID LOWER MICHIGAN WILL PUSH INITIAL PRECIPITATION ACTIVITY EAST OF THE AREA. IN FACT...ALL TERMINALS ARE CURRENTLY REPORTING NO PRECIPITATION. OUTSIDE OF A COUPLE ROGUE SPRINKLES...EXPECT DRY CONDITIONS FOR THE NEXT 3 HOURS. THE NEXT FEATURE TO MONITOR WILL BE AN ATTENDANT COLD FRONT THAT WILL SWING THROUGH SOUTHEASTERN MICHIGAN BETWEEN 21-00Z. FORCING ALONG AND AHEAD OF THE COLD FRONT IS EXPECTED TO ACT ON INCREASING LOWER ATMOSPHERIC INSTABILITY TO CAUSE SHOWERS/CONVECTION TO INITIATE OVERHEAD. PRECIPITATION RATES WITHIN THE CONVECTION COULD YIELD GRAUPEL OR ICE PELLETS. SOME QUESTION AS TO HOW WARM THE NEAR SURFACE LAYER WILL GET...WHICH BRINGS SOME PRECIPITATION TYPE CONCERNS. KEPT A SNOW MENTION IN WITH CONVECTIVE RAIN/PL AT KFNT...WHILE MAINTAINED AN ALL SNOW MENTION AT KMBS. THE STRENGTH OF THE COLD AIR ADVECTION MAY SUPPORT A GOOD WESTERLY POP OF WIND POST COLD FRONT...POTENTIALLY UP TO 30 KNOTS. FOR DTW...CONFIDENCE HAS INCREASED THAT CONVECTIVE RAIN SHOWERS WILL DEVELOP ALONG AN APPROACHING COLD FRONT. THIS IS EXPECTED TO OCCUR BETWEEN 21-00Z. GRAUPEL OR PL WILL BE POSSIBLE IN THE HEAVIEST CONVECTIVE CELLS. AFTER THE COLD FRONT...CONDITIONS WILL QUIET DOWN THIS EVENING BEFORE LIGHT SNOW SHOWERS/FLURRIES BECOME POSSIBLE AGAIN AFTER 7Z. //DTW THRESHOLD THREATS... * HIGH CONFIDENCE IN CEILING HEIGHTS BELOW 5000 FEET THROUGHOUT MUCH IF NOT ALL OF THE TAF PERIOD. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... BRISK WIND ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING SAGINAW BAY...FROM 7 PM THURSDAY TO 10 AM FRIDAY. LAKE ST CLAIR... BRISK WIND ADVISORY...UNTIL 4 AM FRIDAY. MI WATERS OF LAKE ERIE... BRISK WIND ADVISORY...UNTIL 4 AM FRIDAY. && $$ SHORT TERM...CB LONG TERM....HLO MARINE.......CB AVIATION.....CB YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1243 PM EST THU FEB 14 2013 .UPDATE... ISSUED AT 947 AM EST THU FEB 14 2013 NO CHANGES PLANNED TO THE ONGOING HEADLINES THIS MORNING. SNOWFALL REPORTS ACROSS NORTHEAST WI AND SOUTHERN MENOMINEE COUNTY HAVE BEEN AROUND 3 INCHES. WITH MODERATE SNOW EXPECTED TO CONTINUE FOR ANOTHER FEW HOURS...THE GOING 3 TO 5 INCH FORECAST LOOKS ON TRACK. THE ONE LOCATION WHERE AMOUNTS MAY END UP A LITTLE HIGHER THAT PREVIOUSLY FORECAST IS ACROSS SOUTHERN DELTA AND SCHOOLCRAFT COUNTIES...MAINLY OVER THE GARDEN AND STONINGTON PENINSULAS...WHERE THE SNOW RATIOS HAVE BEEN A LITTLE HIGHER THAN FARTHER SOUTH. REPORTS OF 1.5 TO 2 INCHES HAVE BEEN COMMON ALONG LAKE MI. WITH ANOTHER INCH OR SO POSSIBLE WITH A HEAVIER BAND OF SNOW FOCUSED UNDER 900 TO 850MB FRONTOGENESIS. WILL ISSUE A SPECIAL WX STATEMENT FOR THOSE LOCATIONS FOR LOCAL SNOW AMOUNTS UP TO 3 INCHES. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 448 AM EST THU FEB 14 2013 ATTENTION INITIALLY THIS MORNING IS ON THE LOW TRACKING THROUGH WISCONSIN THAT WILL TRACK TO THE EAST-NORTHEAST AND INTO NORTHERN LOWER MICHIGAN THIS MORNING. FORTUNATELY...MODELS HAVE COME INTO MUCH BETTER AGREEMENT ON THE TRACK OF THIS LOW FROM 24 HOURS AGO. STRONG SHORTWAVE NOTED ON WV IMAGERY IN SOUTHWEST WISCONSIN WITH A SECONDARY WAVE UPSTREAM IN NORTH DAKOTA. THIS SECONDARY WAVE WILL BE THE ONE THAT AMPLIFIES THE TROUGH OVER THE GREAT LAKES AND LEADS TO BELOW NORMAL TEMPERATURES AND LAKE EFFECT FOR TONIGHT INTO SATURDAY. BOTH THE LOW AND SHORTWAVE HAVE STARTED TO SHIFT MORE TO THE EAST IN THE LAST HOUR OR TWO...AS THE MODELS HAVE SHOWN. THIS LEADS TO A LITTLE MORE CONFIDENCE ON THE TRACK OF THE LOW AND ASSOCIATED PRECIPITATION ON THE NORTH SIDE FOR THIS MORNING. FAIRLY BROAD AREA OF LIGHT TO MODERATE SNOW ACROSS CENTRAL AND NORTHEAST WISCONSIN AS OF 4AM...WITH LIGHT SNOW OVER SOUTH CENTRAL UPPER MICHIGAN. USING LATEST RADAR DATA...IT APPEARS THIS STRONGEST PRECIPITATION IS TIED TO THE 900-800MB FGEN AND FN CONVERGENCE...WITH THE BROAD AREA OF LIGHT SNOW IN THE 750-650MB FGEN/Q-VECTOR CONV. TRACKING THIS TO THE EAST-NORTHEAST WITH THE LATEST RAP AND GFS/NAM...WOULD EXPECT THE LIGHT SNOW TO SLIDE ACROSS LOCATIONS SOUTHEAST OF WATERSMEET TO GWINN TO SENEY THROUGH THE MORNING HOURS. THE HEAVIEST SNOW SHOULD FOCUS OVER THE SOUTHERN HALF/THIRD OF MENOMINEE COUNTY FROM 12-17Z. 00Z NAM ACTUALLY KEPT THAT BEST FGEN AREA JUST SOUTH OF THE CWA...BUT THE 06Z RUN AND LATEST RAP/HRRR WOULD SUPPORT THE BEST SNOW ALONG AND SOUTH OF A LINE FROM ATHELSTANE WISCONSIN...TO BAGLEY...TO THE MENOMINEE/DELTA COUNTY LINE. SNOW RATIOS SHOULD BE AROUND 13 TO 1 WITH THE NARROW DGZ AND MUCH OF THE LOWER LEVEL FORCING AT OR BELOW THE DGZ. THUS...WITH QPF AMOUNTS TOWARDS 0.25-0.35 IN THAT HEAVIEST BAND...WOULD EXPECT THE SOUTHERN HALF OF MENOMINEE COUNTY TO SEE 2-4 INCHES OF SNOW. THE CITY OF MENOMINEE WOULD HAVE THE BEST OPPORTUNITY FOR SLIGHTLY HIGHER AMOUNTS TOWARDS 5 INCHES...DEPENDING ON WHERE THAT HEAVIEST BAND TRACKS THROUGH NORTHEAST WISCONSIN. WILL LEAVE THE ADVISORY AS IS SINCE THINKS LOOK TO BE IN DECENT SHAPE WITH THE TRACK OF THE HEAVIEST PRECIPITATION AND TIMING. ONE FINAL NOTE...THE RAP/HRRR DO BRING SOME OF THE HEAVIER SNOW INTO FAR SOUTHERN DELTA/SCHOOLCRAFT COUNTIES FOR LOCATIONS RIGHT ALONG LAKE MICHIGAN...BUT WILL WAIT TO SEE HOW THINGS EVOLVED BEFORE ISSUING AN SPS. AS THIS LOW SHIFTS TO THE EAST...EXPECT NORTHWESTERLY FLOW TO SLOWLY DROP 850MB TEMPS TOWARDS -17C BY 00Z FRIDAY. WITH LAKE SUPERIOR TEMPS IN THE 1-2C RANGE...EXPECT LAKE SOME LAKE ENHANCEMENT FOR THE FIRST PART OF THE DAY IN NORTHERLY WIND FAVORED LOCATIONS OVER THE WEST AND NORTH CENTRAL. THIS WILL TRANSITION TO PURE LAKE EFFECT BY EVENING AS THE DEEPER MOISTURE DEPARTS AND DELTA-T VALUES PUSH TOWARDS 18. EVEN THOUGH CONDITIONS BECOME FAVORABLE THIS EVENING AND THROUGH THE NIGHT...THERE IS SOME CONCERN IN THE AMOUNT OF SNOW THAT WILL FALL. THIS IS DUE TO THE DRY AIR WORKING IN BEHIND THE LOW...WHICH WILL KEEP INVERSION HEIGHTS TOWARD 5KFT OR EVEN LOWER IF OUR LOCAL WRF RUNS ARE CORRECT. A LINGERING TROUGH OVER THE EASTERN LAKE FROM THE LOW WILL LEAD TO WINDS OUT OF THE NNW TONIGHT AND HAVE FOLLOWED LOCAL CLIMATOLOGY POPS. EXPECT THE LAKE EFFECT TO BE BEST TONIGHT OVER THE WEST FIRST...ESPECIALLY TOWARDS WESTERN GOGEBIC/ONTONAGON COUNTIES WHERE THERE IS A SLIGHTLY LONGER FETCH AND THEN INCREASING OVERNIGHT OVER THE EAST AS THE COLDER AIR ARRIVES AND PUSHES THE CLOUD IN THE DGZ. LAKE ENHANCEMENT TODAY SHOULD HAVE LOWER SNOW RATIOS...IN THE MID TEENS...BUT AS THE COLDER AIR ARRIVES TONIGHT MUCH OF THE CLOUD WILL BE WITHIN THE DGZ AND EXPECT RATIOS TO RISE TOWARDS 30-1 BY FRIDAY MORNING. WOULD THINK THE VERY FLUFFY NATURE OF THE SNOW WILL TRY TO OFFSET THE LOWER INVERSION HEIGHTS AND STILL PUSH VALUES TOWARDS LOW END ADVISORY AMOUNTS BY FRIDAY MORNING IN THE LONGER FETCH AREAS...GOGEBIC/ONTONAGON/ALGER. SINCE IT WILL MAINLY BE DURING THE OVERNIGHT HOURS AND LIMITED IMPACT WITH THE FLUFFINESS...WILL NOT ISSUE AN ADVISORY AT THIS POINT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 448 AM EST THU FEB 14 2013 AN ACTIVE PATTERN WILL BE THE RULE ACROSS THE CONUS THRU THE LONG TERM AND PROBABLY RIGHT THRU THE END OF THE MONTH. SPLIT FLOW WILL GENERALLY DOMINATE WITH AN ENERGETIC SRN STREAM THOUGH FLOW WILL BE MORE CONSOLIDATED AT TIMES. AS IT HAS FOR DAYS...GFS LONG RANGE RUNS CONTINUE TO SHOW A SERIES OF POTENTIALLY SIGNIFICANT SRN STREAM SYSTEMS MOVING ACROSS THE CONUS THRU THE END OF THE MONTH. WHETHER ANY OF THESE SYSTEMS LIFT FAR ENOUGH N AND/OR PHASE WITH THE NRN STREAM TO BRING A SIGNIFICANT STORM SYSTEM INTO THE UPPER GREAT LAKES REMAINS TO BE SEEN. ONE THING THAT MAY EVENTUALLY FAVOR THE STORM TRACK PROGRESSIVELY SHIFTING NW WITH TIME ACROSS THE CONUS... ALLOWING SYSTEMS TO LIFT FARTHER N AND W FROM THE SRN ROCKIES...IS THE MJO WHICH HAS BEEN ACTIVE SINCE EARLY JAN. WHILE THE RECENT PHASE OF THE MJO HAS BEEN SUPPORTIVE OF COLDER WEATHER OVER THE GREAT LAKES...THAT WILL CHANGE OVER THE NEXT COUPLE OF WEEKS AS THE SHIFTING MJO PHASE BEGINS TO FAVOR RIDGING/WARMER CONDITIONS OVER THE ERN CONUS AND TROFFING/COLDER WEATHER OVER THE W. THIS WOULD AT LEAST SUPPORT A TENDENCY FOR ACTIVE SYSTEMS TO LIFT INTO THE GREAT LAKES LATER THIS MONTH. FOR UPPER MI...THE LONG TERM PORTION OF THE FCST TODAY STILL DOESN`T APPEAR TO OFFER ANY SIGNIFICANT SYSTEMS... BUT THERE WILL BE ONE TO WATCH JUST BEYOND THE TIME PERIOD OF THIS FCST AT THE END OF NEXT WEEK. BEHIND THE CLIPPER MOVING THRU THE GREAT LAKES TODAY...INFLUX OF ARCTIC AIR UNDERNEATH DEEPENING MID/UPPER TROF WILL LEAD TO LES THRU AT LEAST THE FIRST HALF OF THE WEEKEND. MODERATION WILL OCCUR BRIEFLY EARLY NEXT WEEK. THEN...A NEW TROF AMPLIFYING INTO THE CNTRL/ERN CONUS WILL BRING THE POTENTIAL FOR A PHASING SYSTEM OVER THE GREAT LAKES/ERN CONUS EARLY NEXT WEEK. HOW MUCH IMPACT THAT SYSTEM WILL HAVE OVER UPPER MI REMAINS TO BE SEEN. MID/UPPER LEVEL TROF WILL BE STEADILY DEEPENING OVER THE GREAT LAKES FRI/FRI NIGHT...AND WITH 850MB TEMPS AROUND -20C...LES WILL BE THE RULE DOWNWIND OF LAKE SUPERIOR. AT THE LOW-LEVELS...GENERAL NORTHWEST WINDS FRI WILL SHIFT A LITTLE MORE NORTHERLY FRI NIGHT. LAND BREEZES...ESPECIALLY FRI NIGHT/SAT MORNING...WILL HAVE SOME INFLUENCE ON THE WIND FIELD AND WILL SERVE TO FOCUS HEAVIER LES. INITIALLY...INVERSION FRI MORNING WILL BE AROUND 4-5KFT...BUT WILL STEADILY RISE UNDER DEEPENING MID LEVEL TROF...REACHING 8-10KFT FRI NIGHT. INVERSION MAY EVEN DISAPPEAR FOR A TIME FRI NIGHT PER GFS/NAM FCST SOUNDINGS AS TROF REACHES ITS DEEPEST OVER THE UPPER LAKES. SO...EXPECT A STEADY INCREASE IN LES INTENSITY FRI...AND THEN SNOW WILL PROBABLY BECOME HVY AT TIMES FRI NIGHT...IN PARTICULAR WHERE CONVERGENCE ZONES SET UP DUE TO LAND BREEZES. ALTHOUGH DGZ WILL BE PUSHED TOWARD THE SFC BY THE COLDER AIR OVER THE AREA...NAM FCST SOUNDINGS SHOW SUFFICIENT LAKE MODERATION TO KEEP DGZ AT LEAST IN THE LOWER PORTION OF THE CONVECTIVE LAYER. LONGER FETCH ACROSS THE E HALF OF LAKE SUPERIOR INTO NCNTRL UPPER MI SHOULD HELP KEEP DGZ HIGHER AND BETTER POSITIONED IN THE CONVECTIVE LAYER. AS A RESULT... EXPECT SNOW TO WATER RATIOS TO END UP AROUND 30 TO 1. AT THIS POINT...EXPECT ADVY LEVEL LES FOR THE MOST PART IN THE SNOWBELTS FAVORED BY NW WINDS FRI. SNOWFALL COULD THEN PUSH WARNING CRITERIA FRI NIGHT OVER GOGEBIC/ONTONAGON COUNTIES AND MORE SO OVER ALGER/NRN SCHOOLCRAFT COUNTIES AND PERHAPS FAR ERN MARQUETTE COUNTY DEPENDING ON HOW LAND BREEZE CONVERGENCE EVOLVES FRI NIGHT/SAT MORNING. SINCE POTENTIAL FOR WARNING AMOUNTS (8 INCHES OR MORE IN 12HRS OR 12 OR MORE IN 24HRS) IS FAIRLY HIGH FOR ALGER/NRN SCHOOLCRAFT...WILL ISSUE A LAKE EFFECT SNOW WATCH THERE FOR FRI THRU SAT MORNING. IN THE OTHER AREAS AFFECTED BY LES...ADVYS WILL PROBABLY WORK OUT. GIVEN THAT IT`S 3RD PERIOD...ESPECIALLY LATER 3RD PERIOD THAT SNOW REALLY PICKS UP...INTO A 4TH PERIOD EVENT...WILL NOT ISSUE ADVYS WITH THIS FCST ISSUANCE. SAT/SAT NIGHT...MID/UPPER TROF SHIFTS E AND SFC HIGH PRES RIDGE PUSHES INTO THE WRN GREAT LAKES. UNDER RISING HEIGHTS...INVERSIONS WILL FALL...RESULTING IN LES INTENSITY QUICKLY DIMINISHING W TO E. AS WINDS BACK W THEN SW SAT AFTN/SAT NIGHT...LINGERING LES WILL SHIFT...EVENTUALLY MOVING OUT OF THE FCST AREA...BUT PROBABLY NOT UNTIL LATE SAT NIGHT OVER THE NE. WITH A POTENTIAL PERIOD OF CLEAR SKIES/CALM WIND AS SFC HIGH PASSES OVER THE AREA SAT NIGHT...TEMPS COULD TANK. DROPPED MINS CONSIDERABLY FROM PREVIOUS FCST TO -10 TO -15F IN THE TRADITIONAL INTERIOR COLD SPOTS OVER THE W HALF. COULD BE SIMILAR READINGS OVER THE E IF CLEARING SPREADS THAT FAR E. IF THERE ENDS UP BEING SEVERAL HRS OF CLEAR SKIES/CALM WINDS...SOME TRADITIONAL COLD SPOTS MAY FALL BLO -20F. SUN...MID LEVEL RIDGE WILL BUILD INTO THE GREAT LAKES DOWNSTREAM OF NEXT TROF AMPLIFYING S INTO THE ROCKIES/WRN PLAINS. FAIRLY STRONG WAA PATTERN COULD LEAD TO SOME -SN SUN...BUT ECWMF/GFS HOLD STRONGEST WAA OFF TO THE W AND NW OF UPPER MI. SO...WILL PLAN FOR A DRY DAY SUN. TROF DIGGING INTO THE ROCKIES/WRN PLAINS SUN WILL SHIFT E...REACHING THE MISSISSIPPI VALLEY MON...THE GREAT LAKES TUE AND NEW ENGLAND WED. TROF TAKES ON A NEGATIVE TILT AFTER PASSING THE WRN GREAT LAKES...SO WOULD EXPECT THE MORE SIGNIFICANT PCPN WITH THE TROF TO BE E OF HERE. NONETHELESS...THERE COULD BE SOME ACCUMULATING SNOW AS THE SYSTEM PASSES ACROSS THE AREA MON...DEPENDING ON HOW QUICKLY THE ASSOCIATED SFC LOW ORGANIZES AND WHAT TRACK IT TAKES. RIGHT NOW...IT APPEARS THE SFC LOW WILL TRACK ACROSS UPPER MI WHICH SHOULD KEEP HEAVIER SNOW TO THE N OF HERE. HOWEVER...SINCE THIS SYSTEM IS SEVERAL DAYS OUT...INTENSITY/TRACK OF SYSTEM COULD CHANGE QUITE A BIT. WHAT IS MORE CERTAIN IS THAT ARCTIC AIR WILL AGAIN DUMP INTO THE UPPER LAKES MON NIGHT/TUE ON NORTHERLY WINDS...BRINGING ANOTHER ROUND OF LES DOWNWIND OF LAKE SUPERIOR. RAISED POPS WELL ABOVE CONSENSUS TO LIKELY/CATEGORICAL TO REFLECT THE GOOD RUN-TO-RUN CONSISTENCY OF MEDIUM RANGE GUIDANCE ON THE MAGNITUDE OF THE INCOMING COLD THAT WILL BE MUCH MORE THAN SUFFICIENT FOR LES. LES WILL GRADUALLY WIND DOWN WED AS TROF DEPARTS AND RIDGE BUILDS INTO THE UPPER MISSISSIPPI VALLEY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1242 PM EST THU FEB 14 2013 AN INITIAL BURST OF LAKE-ENHANCED SNOW ON THE BACKSIDE OF A DEPARTING CLIPPER SYSTEM IS RESULTING IN CIGS AND VIS ON THE LIFR/IFR THRESHOLD AT ALL SITES. EXPECT VIS TO IMPROVE AND -SHSN TO DIMINISH THIS AFTERNOON AS MOISTURE FROM THE SYSTEM PULLS OUT OF THE AREA. THEN LATE TONIGHT...LES INTENSITY WILL INCREASE AT MAINLY IWD AND CMX AS WNW TO NW WINDS BRING ARCTIC AIR OVER LAKE SUPERIOR. VIS WILL FALL TO NEAR LIFR LEVELS...AND WILL LIKELY DROP LOWER AT TIMES UNDER HEAVIER LES BANDS ON FRIDAY. IWD HAS THE BIGGEST QUESTION MARK AS IT LOOKS LIKE A SIGNIFICANT LES BAND WILL SET UP JUST NORTH OF THE TERMINAL. IF THIS BAND DRIFTS SOUTH AT TIMES FRIDAY MORNING...VIS COULD FALL BELOW AIRFIELD LANDING MINS FOR AN EXTENDED PERIOD. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 448 AM EST THU FEB 14 2013 A LOW PRESSURE SYSTEM MOVING THROUGH WISCONSIN THIS MORNING WILL SHIFT EAST TO QUEBEC TONIGHT AND LEAD TO INCREASING NORTHERLY WINDS THIS AFTERNOON. EXPECT MOST LOCATIONS TO BE IN THE 20-30KT RANGE...BUT THERE COULD BE A FEW GALE FORCE GUSTS TO 35 KNOTS OVER THE CENTRAL PART OF LAKE SUPERIOR. COLDER AIR AND PERSISTENT NORTH TO NORTHWEST WINDS TONIGHT INTO SATURDAY MORNING WILL LEAD TO HEAVY FREEZING SPRAY AND HAVE ISSUED A HEAVY FREEZING SPRAY WARNING FOR PORTIONS OF LAKE SUPERIOR. HIGH PRESSURE WILL THEN BUILD IN ON SATURDAY AND SUNDAY FROM THE NORTHERN PLAINS AND DECREASE THE WINDS BELOW 15KTS. THEN AS A LOW PRESSURE SYSTEM APPROACHES LAKE SUPERIOR ON SUNDAY AND MOVES THROUGH ON MONDAY...EXPECT SOUTHERLY WINDS TO INCREASE TO 20-25KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW WATCH FROM FRIDAY MORNING THROUGH SATURDAY AFTERNOON FOR MIZ006-085. WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MIZ012. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING FROM 7 PM THIS EVENING TO 7 AM EST SATURDAY FOR LSZ264>266. LAKE MICHIGAN... NONE. && $$ UPDATE...TK SHORT TERM...SRF LONG TERM...ROLFSON AVIATION...TK MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
951 AM EST THU FEB 14 2013 .UPDATE... ISSUED AT 947 AM EST THU FEB 14 2013 NO CHANGES PLANNED TO THE ONGOING HEADLINES THIS MORNING. SNOWFALL REPORTS ACROSS NORTHEAST WI AND SOUTHERN MENOMINEE COUNTY HAVE BEEN AROUND 3 INCHES. WITH MODERATE SNOW EXPECTED TO CONTINUE FOR ANOTHER FEW HOURS...THE GOING 3 TO 5 INCH FORECAST LOOKS ON TRACK. THE ONE LOCATION WHERE AMOUNTS MAY END UP A LITTLE HIGHER THAT PREVIOUSLY FORECAST IS ACROSS SOUTHERN DELTA AND SCHOOLCRAFT COUNTIES...MAINLY OVER THE GARDEN AND STONINGTON PENINSULAS...WHERE THE SNOW RATIOS HAVE BEEN A LITTLE HIGHER THAN FARTHER SOUTH. REPORTS OF 1.5 TO 2 INCHES HAVE BEEN COMMON ALONG LAKE MI. WITH ANOTHER INCH OR SO POSSIBLE WITH A HEAVIER BAND OF SNOW FOCUSED UNDER 900 TO 850MB FRONTOGENESIS. WILL ISSUE A SPECIAL WX STATEMENT FOR THOSE LOCATIONS FOR LOCAL SNOW AMOUNTS UP TO 3 INCHES. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 448 AM EST THU FEB 14 2013 ATTENTION INITIALLY THIS MORNING IS ON THE LOW TRACKING THROUGH WISCONSIN THAT WILL TRACK TO THE EAST-NORTHEAST AND INTO NORTHERN LOWER MICHIGAN THIS MORNING. FORTUNATELY...MODELS HAVE COME INTO MUCH BETTER AGREEMENT ON THE TRACK OF THIS LOW FROM 24 HOURS AGO. STRONG SHORTWAVE NOTED ON WV IMAGERY IN SOUTHWEST WISCONSIN WITH A SECONDARY WAVE UPSTREAM IN NORTH DAKOTA. THIS SECONDARY WAVE WILL BE THE ONE THAT AMPLIFIES THE TROUGH OVER THE GREAT LAKES AND LEADS TO BELOW NORMAL TEMPERATURES AND LAKE EFFECT FOR TONIGHT INTO SATURDAY. BOTH THE LOW AND SHORTWAVE HAVE STARTED TO SHIFT MORE TO THE EAST IN THE LAST HOUR OR TWO...AS THE MODELS HAVE SHOWN. THIS LEADS TO A LITTLE MORE CONFIDENCE ON THE TRACK OF THE LOW AND ASSOCIATED PRECIPITATION ON THE NORTH SIDE FOR THIS MORNING. FAIRLY BROAD AREA OF LIGHT TO MODERATE SNOW ACROSS CENTRAL AND NORTHEAST WISCONSIN AS OF 4AM...WITH LIGHT SNOW OVER SOUTH CENTRAL UPPER MICHIGAN. USING LATEST RADAR DATA...IT APPEARS THIS STRONGEST PRECIPITATION IS TIED TO THE 900-800MB FGEN AND FN CONVERGENCE...WITH THE BROAD AREA OF LIGHT SNOW IN THE 750-650MB FGEN/Q-VECTOR CONV. TRACKING THIS TO THE EAST-NORTHEAST WITH THE LATEST RAP AND GFS/NAM...WOULD EXPECT THE LIGHT SNOW TO SLIDE ACROSS LOCATIONS SOUTHEAST OF WATERSMEET TO GWINN TO SENEY THROUGH THE MORNING HOURS. THE HEAVIEST SNOW SHOULD FOCUS OVER THE SOUTHERN HALF/THIRD OF MENOMINEE COUNTY FROM 12-17Z. 00Z NAM ACTUALLY KEPT THAT BEST FGEN AREA JUST SOUTH OF THE CWA...BUT THE 06Z RUN AND LATEST RAP/HRRR WOULD SUPPORT THE BEST SNOW ALONG AND SOUTH OF A LINE FROM ATHELSTANE WISCONSIN...TO BAGLEY...TO THE MENOMINEE/DELTA COUNTY LINE. SNOW RATIOS SHOULD BE AROUND 13 TO 1 WITH THE NARROW DGZ AND MUCH OF THE LOWER LEVEL FORCING AT OR BELOW THE DGZ. THUS...WITH QPF AMOUNTS TOWARDS 0.25-0.35 IN THAT HEAVIEST BAND...WOULD EXPECT THE SOUTHERN HALF OF MENOMINEE COUNTY TO SEE 2-4 INCHES OF SNOW. THE CITY OF MENOMINEE WOULD HAVE THE BEST OPPORTUNITY FOR SLIGHTLY HIGHER AMOUNTS TOWARDS 5 INCHES...DEPENDING ON WHERE THAT HEAVIEST BAND TRACKS THROUGH NORTHEAST WISCONSIN. WILL LEAVE THE ADVISORY AS IS SINCE THINKS LOOK TO BE IN DECENT SHAPE WITH THE TRACK OF THE HEAVIEST PRECIPITATION AND TIMING. ONE FINAL NOTE...THE RAP/HRRR DO BRING SOME OF THE HEAVIER SNOW INTO FAR SOUTHERN DELTA/SCHOOLCRAFT COUNTIES FOR LOCATIONS RIGHT ALONG LAKE MICHIGAN...BUT WILL WAIT TO SEE HOW THINGS EVOLVED BEFORE ISSUING AN SPS. AS THIS LOW SHIFTS TO THE EAST...EXPECT NORTHWESTERLY FLOW TO SLOWLY DROP 850MB TEMPS TOWARDS -17C BY 00Z FRIDAY. WITH LAKE SUPERIOR TEMPS IN THE 1-2C RANGE...EXPECT LAKE SOME LAKE ENHANCEMENT FOR THE FIRST PART OF THE DAY IN NORTHERLY WIND FAVORED LOCATIONS OVER THE WEST AND NORTH CENTRAL. THIS WILL TRANSITION TO PURE LAKE EFFECT BY EVENING AS THE DEEPER MOISTURE DEPARTS AND DELTA-T VALUES PUSH TOWARDS 18. EVEN THOUGH CONDITIONS BECOME FAVORABLE THIS EVENING AND THROUGH THE NIGHT...THERE IS SOME CONCERN IN THE AMOUNT OF SNOW THAT WILL FALL. THIS IS DUE TO THE DRY AIR WORKING IN BEHIND THE LOW...WHICH WILL KEEP INVERSION HEIGHTS TOWARD 5KFT OR EVEN LOWER IF OUR LOCAL WRF RUNS ARE CORRECT. A LINGERING TROUGH OVER THE EASTERN LAKE FROM THE LOW WILL LEAD TO WINDS OUT OF THE NNW TONIGHT AND HAVE FOLLOWED LOCAL CLIMATOLOGY POPS. EXPECT THE LAKE EFFECT TO BE BEST TONIGHT OVER THE WEST FIRST...ESPECIALLY TOWARDS WESTERN GOGEBIC/ONTONAGON COUNTIES WHERE THERE IS A SLIGHTLY LONGER FETCH AND THEN INCREASING OVERNIGHT OVER THE EAST AS THE COLDER AIR ARRIVES AND PUSHES THE CLOUD IN THE DGZ. LAKE ENHANCEMENT TODAY SHOULD HAVE LOWER SNOW RATIOS...IN THE MID TEENS...BUT AS THE COLDER AIR ARRIVES TONIGHT MUCH OF THE CLOUD WILL BE WITHIN THE DGZ AND EXPECT RATIOS TO RISE TOWARDS 30-1 BY FRIDAY MORNING. WOULD THINK THE VERY FLUFFY NATURE OF THE SNOW WILL TRY TO OFFSET THE LOWER INVERSION HEIGHTS AND STILL PUSH VALUES TOWARDS LOW END ADVISORY AMOUNTS BY FRIDAY MORNING IN THE LONGER FETCH AREAS...GOGEBIC/ONTONAGON/ALGER. SINCE IT WILL MAINLY BE DURING THE OVERNIGHT HOURS AND LIMITED IMPACT WITH THE FLUFFINESS...WILL NOT ISSUE AN ADVISORY AT THIS POINT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 448 AM EST THU FEB 14 2013 AN ACTIVE PATTERN WILL BE THE RULE ACROSS THE CONUS THRU THE LONG TERM AND PROBABLY RIGHT THRU THE END OF THE MONTH. SPLIT FLOW WILL GENERALLY DOMINATE WITH AN ENERGETIC SRN STREAM THOUGH FLOW WILL BE MORE CONSOLIDATED AT TIMES. AS IT HAS FOR DAYS...GFS LONG RANGE RUNS CONTINUE TO SHOW A SERIES OF POTENTIALLY SIGNIFICANT SRN STREAM SYSTEMS MOVING ACROSS THE CONUS THRU THE END OF THE MONTH. WHETHER ANY OF THESE SYSTEMS LIFT FAR ENOUGH N AND/OR PHASE WITH THE NRN STREAM TO BRING A SIGNIFICANT STORM SYSTEM INTO THE UPPER GREAT LAKES REMAINS TO BE SEEN. ONE THING THAT MAY EVENTUALLY FAVOR THE STORM TRACK PROGRESSIVELY SHIFTING NW WITH TIME ACROSS THE CONUS... ALLOWING SYSTEMS TO LIFT FARTHER N AND W FROM THE SRN ROCKIES...IS THE MJO WHICH HAS BEEN ACTIVE SINCE EARLY JAN. WHILE THE RECENT PHASE OF THE MJO HAS BEEN SUPPORTIVE OF COLDER WEATHER OVER THE GREAT LAKES...THAT WILL CHANGE OVER THE NEXT COUPLE OF WEEKS AS THE SHIFTING MJO PHASE BEGINS TO FAVOR RIDGING/WARMER CONDITIONS OVER THE ERN CONUS AND TROFFING/COLDER WEATHER OVER THE W. THIS WOULD AT LEAST SUPPORT A TENDENCY FOR ACTIVE SYSTEMS TO LIFT INTO THE GREAT LAKES LATER THIS MONTH. FOR UPPER MI...THE LONG TERM PORTION OF THE FCST TODAY STILL DOESN`T APPEAR TO OFFER ANY SIGNIFICANT SYSTEMS... BUT THERE WILL BE ONE TO WATCH JUST BEYOND THE TIME PERIOD OF THIS FCST AT THE END OF NEXT WEEK. BEHIND THE CLIPPER MOVING THRU THE GREAT LAKES TODAY...INFLUX OF ARCTIC AIR UNDERNEATH DEEPENING MID/UPPER TROF WILL LEAD TO LES THRU AT LEAST THE FIRST HALF OF THE WEEKEND. MODERATION WILL OCCUR BRIEFLY EARLY NEXT WEEK. THEN...A NEW TROF AMPLIFYING INTO THE CNTRL/ERN CONUS WILL BRING THE POTENTIAL FOR A PHASING SYSTEM OVER THE GREAT LAKES/ERN CONUS EARLY NEXT WEEK. HOW MUCH IMPACT THAT SYSTEM WILL HAVE OVER UPPER MI REMAINS TO BE SEEN. MID/UPPER LEVEL TROF WILL BE STEADILY DEEPENING OVER THE GREAT LAKES FRI/FRI NIGHT...AND WITH 850MB TEMPS AROUND -20C...LES WILL BE THE RULE DOWNWIND OF LAKE SUPERIOR. AT THE LOW-LEVELS...GENERAL NORTHWEST WINDS FRI WILL SHIFT A LITTLE MORE NORTHERLY FRI NIGHT. LAND BREEZES...ESPECIALLY FRI NIGHT/SAT MORNING...WILL HAVE SOME INFLUENCE ON THE WIND FIELD AND WILL SERVE TO FOCUS HEAVIER LES. INITIALLY...INVERSION FRI MORNING WILL BE AROUND 4-5KFT...BUT WILL STEADILY RISE UNDER DEEPENING MID LEVEL TROF...REACHING 8-10KFT FRI NIGHT. INVERSION MAY EVEN DISAPPEAR FOR A TIME FRI NIGHT PER GFS/NAM FCST SOUNDINGS AS TROF REACHES ITS DEEPEST OVER THE UPPER LAKES. SO...EXPECT A STEADY INCREASE IN LES INTENSITY FRI...AND THEN SNOW WILL PROBABLY BECOME HVY AT TIMES FRI NIGHT...IN PARTICULAR WHERE CONVERGENCE ZONES SET UP DUE TO LAND BREEZES. ALTHOUGH DGZ WILL BE PUSHED TOWARD THE SFC BY THE COLDER AIR OVER THE AREA...NAM FCST SOUNDINGS SHOW SUFFICIENT LAKE MODERATION TO KEEP DGZ AT LEAST IN THE LOWER PORTION OF THE CONVECTIVE LAYER. LONGER FETCH ACROSS THE E HALF OF LAKE SUPERIOR INTO NCNTRL UPPER MI SHOULD HELP KEEP DGZ HIGHER AND BETTER POSITIONED IN THE CONVECTIVE LAYER. AS A RESULT... EXPECT SNOW TO WATER RATIOS TO END UP AROUND 30 TO 1. AT THIS POINT...EXPECT ADVY LEVEL LES FOR THE MOST PART IN THE SNOWBELTS FAVORED BY NW WINDS FRI. SNOWFALL COULD THEN PUSH WARNING CRITERIA FRI NIGHT OVER GOGEBIC/ONTONAGON COUNTIES AND MORE SO OVER ALGER/NRN SCHOOLCRAFT COUNTIES AND PERHAPS FAR ERN MARQUETTE COUNTY DEPENDING ON HOW LAND BREEZE CONVERGENCE EVOLVES FRI NIGHT/SAT MORNING. SINCE POTENTIAL FOR WARNING AMOUNTS (8 INCHES OR MORE IN 12HRS OR 12 OR MORE IN 24HRS) IS FAIRLY HIGH FOR ALGER/NRN SCHOOLCRAFT...WILL ISSUE A LAKE EFFECT SNOW WATCH THERE FOR FRI THRU SAT MORNING. IN THE OTHER AREAS AFFECTED BY LES...ADVYS WILL PROBABLY WORK OUT. GIVEN THAT IT`S 3RD PERIOD...ESPECIALLY LATER 3RD PERIOD THAT SNOW REALLY PICKS UP...INTO A 4TH PERIOD EVENT...WILL NOT ISSUE ADVYS WITH THIS FCST ISSUANCE. SAT/SAT NIGHT...MID/UPPER TROF SHIFTS E AND SFC HIGH PRES RIDGE PUSHES INTO THE WRN GREAT LAKES. UNDER RISING HEIGHTS...INVERSIONS WILL FALL...RESULTING IN LES INTENSITY QUICKLY DIMINISHING W TO E. AS WINDS BACK W THEN SW SAT AFTN/SAT NIGHT...LINGERING LES WILL SHIFT...EVENTUALLY MOVING OUT OF THE FCST AREA...BUT PROBABLY NOT UNTIL LATE SAT NIGHT OVER THE NE. WITH A POTENTIAL PERIOD OF CLEAR SKIES/CALM WIND AS SFC HIGH PASSES OVER THE AREA SAT NIGHT...TEMPS COULD TANK. DROPPED MINS CONSIDERABLY FROM PREVIOUS FCST TO -10 TO -15F IN THE TRADITIONAL INTERIOR COLD SPOTS OVER THE W HALF. COULD BE SIMILAR READINGS OVER THE E IF CLEARING SPREADS THAT FAR E. IF THERE ENDS UP BEING SEVERAL HRS OF CLEAR SKIES/CALM WINDS...SOME TRADITIONAL COLD SPOTS MAY FALL BLO -20F. SUN...MID LEVEL RIDGE WILL BUILD INTO THE GREAT LAKES DOWNSTREAM OF NEXT TROF AMPLIFYING S INTO THE ROCKIES/WRN PLAINS. FAIRLY STRONG WAA PATTERN COULD LEAD TO SOME -SN SUN...BUT ECWMF/GFS HOLD STRONGEST WAA OFF TO THE W AND NW OF UPPER MI. SO...WILL PLAN FOR A DRY DAY SUN. TROF DIGGING INTO THE ROCKIES/WRN PLAINS SUN WILL SHIFT E...REACHING THE MISSISSIPPI VALLEY MON...THE GREAT LAKES TUE AND NEW ENGLAND WED. TROF TAKES ON A NEGATIVE TILT AFTER PASSING THE WRN GREAT LAKES...SO WOULD EXPECT THE MORE SIGNIFICANT PCPN WITH THE TROF TO BE E OF HERE. NONETHELESS...THERE COULD BE SOME ACCUMULATING SNOW AS THE SYSTEM PASSES ACROSS THE AREA MON...DEPENDING ON HOW QUICKLY THE ASSOCIATED SFC LOW ORGANIZES AND WHAT TRACK IT TAKES. RIGHT NOW...IT APPEARS THE SFC LOW WILL TRACK ACROSS UPPER MI WHICH SHOULD KEEP HEAVIER SNOW TO THE N OF HERE. HOWEVER...SINCE THIS SYSTEM IS SEVERAL DAYS OUT...INTENSITY/TRACK OF SYSTEM COULD CHANGE QUITE A BIT. WHAT IS MORE CERTAIN IS THAT ARCTIC AIR WILL AGAIN DUMP INTO THE UPPER LAKES MON NIGHT/TUE ON NORTHERLY WINDS...BRINGING ANOTHER ROUND OF LES DOWNWIND OF LAKE SUPERIOR. RAISED POPS WELL ABOVE CONSENSUS TO LIKELY/CATEGORICAL TO REFLECT THE GOOD RUN-TO-RUN CONSISTENCY OF MEDIUM RANGE GUIDANCE ON THE MAGNITUDE OF THE INCOMING COLD THAT WILL BE MUCH MORE THAN SUFFICIENT FOR LES. LES WILL GRADUALLY WIND DOWN WED AS TROF DEPARTS AND RIDGE BUILDS INTO THE UPPER MISSISSIPPI VALLEY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 639 AM EST THU FEB 14 2013 A LOW PRESSURE SYSTEM EXITING CENTRAL WISCONSIN THIS MORNING WILL PRODUCE LIGHT SNOW SHOWERS AT KSAW FOR THE FIRST COUPLE OF HOURS OF THE FORECAST. FOCUS THEN TURNS TO LAKE ENHANCED SNOW FOR A PERIOD TODAY...A BRIEF LULL DURING LATE AFTERNOON AND EARLY EVENING BEFORE LAKE EFFECT ARRIVES FOR NORTH-NORTHWEST WIND LOCATIONS. WILL CONTINUE IDEA OF LOWER VISIBILITIES AND CEILINGS WITH LAKE ENHANCED SNOW THROUGH THIS AFTERNOON AT ALL SITES. BUT AS THE LOW QUICKLY DEPARTS THIS AFTERNOON...SUPPORTING DEEP MOISTURE DEPARTS AND EXPECT WEAKENING SNOW SHOWERS INTO THE EVENING. BUT WITH COLDER AIR INCREASING THROUGH THE NIGHT...SHOULD SEE LAKE EFFECT SNOW INTENSIFY AT KIWD/KCMX THROUGH THE NIGHT. KSAW ON THE OTHER HAND WON/T SEE TOO FAVORABLE WIND DIRECTIONS AND HAVE JUST WENT WITH MVFR CEILINGS. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 448 AM EST THU FEB 14 2013 A LOW PRESSURE SYSTEM MOVING THROUGH WISCONSIN THIS MORNING WILL SHIFT EAST TO QUEBEC TONIGHT AND LEAD TO INCREASING NORTHERLY WINDS THIS AFTERNOON. EXPECT MOST LOCATIONS TO BE IN THE 20-30KT RANGE...BUT THERE COULD BE A FEW GALE FORCE GUSTS TO 35 KNOTS OVER THE CENTRAL PART OF LAKE SUPERIOR. COLDER AIR AND PERSISTENT NORTH TO NORTHWEST WINDS TONIGHT INTO SATURDAY MORNING WILL LEAD TO HEAVY FREEZING SPRAY AND HAVE ISSUED A HEAVY FREEZING SPRAY WARNING FOR PORTIONS OF LAKE SUPERIOR. HIGH PRESSURE WILL THEN BUILD IN ON SATURDAY AND SUNDAY FROM THE NORTHERN PLAINS AND DECREASE THE WINDS BELOW 15KTS. THEN AS A LOW PRESSURE SYSTEM APPROACHES LAKE SUPERIOR ON SUNDAY AND MOVES THROUGH ON MONDAY...EXPECT SOUTHERLY WINDS TO INCREASE TO 20-25KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW WATCH FROM FRIDAY MORNING THROUGH SATURDAY AFTERNOON FOR MIZ006-085. WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MIZ012. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING FROM 7 PM THIS EVENING TO 7 AM EST SATURDAY FOR LSZ264>266. LAKE MICHIGAN... NONE. && $$ UPDATE...TK SHORT TERM...SRF LONG TERM...ROLFSON AVIATION...SRF MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
640 AM EST THU FEB 14 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 448 AM EST THU FEB 14 2013 ATTENTION INITIALLY THIS MORNING IS ON THE LOW TRACKING THROUGH WISCONSIN THAT WILL TRACK TO THE EAST-NORTHEAST AND INTO NORTHERN LOWER MICHIGAN THIS MORNING. FORTUNATELY...MODELS HAVE COME INTO MUCH BETTER AGREEMENT ON THE TRACK OF THIS LOW FROM 24 HOURS AGO. STRONG SHORTWAVE NOTED ON WV IMAGERY IN SOUTHWEST WISCONSIN WITH A SECONDARY WAVE UPSTREAM IN NORTH DAKOTA. THIS SECONDARY WAVE WILL BE THE ONE THAT AMPLIFIES THE TROUGH OVER THE GREAT LAKES AND LEADS TO BELOW NORMAL TEMPERATURES AND LAKE EFFECT FOR TONIGHT INTO SATURDAY. BOTH THE LOW AND SHORTWAVE HAVE STARTED TO SHIFT MORE TO THE EAST IN THE LAST HOUR OR TWO...AS THE MODELS HAVE SHOWN. THIS LEADS TO A LITTLE MORE CONFIDENCE ON THE TRACK OF THE LOW AND ASSOCIATED PRECIPITATION ON THE NORTH SIDE FOR THIS MORNING. FAIRLY BROAD AREA OF LIGHT TO MODERATE SNOW ACROSS CENTRAL AND NORTHEAST WISCONSIN AS OF 4AM...WITH LIGHT SNOW OVER SOUTH CENTRAL UPPER MICHIGAN. USING LATEST RADAR DATA...IT APPEARS THIS STRONGEST PRECIPITATION IS TIED TO THE 900-800MB FGEN AND FN CONVERGENCE...WITH THE BROAD AREA OF LIGHT SNOW IN THE 750-650MB FGEN/Q-VECTOR CONV. TRACKING THIS TO THE EAST-NORTHEAST WITH THE LATEST RAP AND GFS/NAM...WOULD EXPECT THE LIGHT SNOW TO SLIDE ACROSS LOCATIONS SOUTHEAST OF WATERSMEET TO GWINN TO SENEY THROUGH THE MORNING HOURS. THE HEAVIEST SNOW SHOULD FOCUS OVER THE SOUTHERN HALF/THIRD OF MENOMINEE COUNTY FROM 12-17Z. 00Z NAM ACTUALLY KEPT THAT BEST FGEN AREA JUST SOUTH OF THE CWA...BUT THE 06Z RUN AND LATEST RAP/HRRR WOULD SUPPORT THE BEST SNOW ALONG AND SOUTH OF A LINE FROM ATHELSTANE WISCONSIN...TO BAGLEY...TO THE MENOMINEE/DELTA COUNTY LINE. SNOW RATIOS SHOULD BE AROUND 13 TO 1 WITH THE NARROW DGZ AND MUCH OF THE LOWER LEVEL FORCING AT OR BELOW THE DGZ. THUS...WITH QPF AMOUNTS TOWARDS 0.25-0.35 IN THAT HEAVIEST BAND...WOULD EXPECT THE SOUTHERN HALF OF MENOMINEE COUNTY TO SEE 2-4 INCHES OF SNOW. THE CITY OF MENOMINEE WOULD HAVE THE BEST OPPORTUNITY FOR SLIGHTLY HIGHER AMOUNTS TOWARDS 5 INCHES...DEPENDING ON WHERE THAT HEAVIEST BAND TRACKS THROUGH NORTHEAST WISCONSIN. WILL LEAVE THE ADVISORY AS IS SINCE THINKS LOOK TO BE IN DECENT SHAPE WITH THE TRACK OF THE HEAVIEST PRECIPITATION AND TIMING. ONE FINAL NOTE...THE RAP/HRRR DO BRING SOME OF THE HEAVIER SNOW INTO FAR SOUTHERN DELTA/SCHOOLCRAFT COUNTIES FOR LOCATIONS RIGHT ALONG LAKE MICHIGAN...BUT WILL WAIT TO SEE HOW THINGS EVOLVED BEFORE ISSUING AN SPS. AS THIS LOW SHIFTS TO THE EAST...EXPECT NORTHWESTERLY FLOW TO SLOWLY DROP 850MB TEMPS TOWARDS -17C BY 00Z FRIDAY. WITH LAKE SUPERIOR TEMPS IN THE 1-2C RANGE...EXPECT LAKE SOME LAKE ENHANCEMENT FOR THE FIRST PART OF THE DAY IN NORTHERLY WIND FAVORED LOCATIONS OVER THE WEST AND NORTH CENTRAL. THIS WILL TRANSITION TO PURE LAKE EFFECT BY EVENING AS THE DEEPER MOISTURE DEPARTS AND DELTA-T VALUES PUSH TOWARDS 18. EVEN THOUGH CONDITIONS BECOME FAVORABLE THIS EVENING AND THROUGH THE NIGHT...THERE IS SOME CONCERN IN THE AMOUNT OF SNOW THAT WILL FALL. THIS IS DUE TO THE DRY AIR WORKING IN BEHIND THE LOW...WHICH WILL KEEP INVERSION HEIGHTS TOWARD 5KFT OR EVEN LOWER IF OUR LOCAL WRF RUNS ARE CORRECT. A LINGERING TROUGH OVER THE EASTERN LAKE FROM THE LOW WILL LEAD TO WINDS OUT OF THE NNW TONIGHT AND HAVE FOLLOWED LOCAL CLIMATOLOGY POPS. EXPECT THE LAKE EFFECT TO BE BEST TONIGHT OVER THE WEST FIRST...ESPECIALLY TOWARDS WESTERN GOGEBIC/ONTONAGON COUNTIES WHERE THERE IS A SLIGHTLY LONGER FETCH AND THEN INCREASING OVERNIGHT OVER THE EAST AS THE COLDER AIR ARRIVES AND PUSHES THE CLOUD IN THE DGZ. LAKE ENHANCEMENT TODAY SHOULD HAVE LOWER SNOW RATIOS...IN THE MID TEENS...BUT AS THE COLDER AIR ARRIVES TONIGHT MUCH OF THE CLOUD WILL BE WITHIN THE DGZ AND EXPECT RATIOS TO RISE TOWARDS 30-1 BY FRIDAY MORNING. WOULD THINK THE VERY FLUFFY NATURE OF THE SNOW WILL TRY TO OFFSET THE LOWER INVERSION HEIGHTS AND STILL PUSH VALUES TOWARDS LOW END ADVISORY AMOUNTS BY FRIDAY MORNING IN THE LONGER FETCH AREAS...GOGEBIC/ONTONAGON/ALGER. SINCE IT WILL MAINLY BE DURING THE OVERNIGHT HOURS AND LIMITED IMPACT WITH THE FLUFFINESS...WILL NOT ISSUE AN ADVISORY AT THIS POINT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 448 AM EST THU FEB 14 2013 AN ACTIVE PATTERN WILL BE THE RULE ACROSS THE CONUS THRU THE LONG TERM AND PROBABLY RIGHT THRU THE END OF THE MONTH. SPLIT FLOW WILL GENERALLY DOMINATE WITH AN ENERGETIC SRN STREAM THOUGH FLOW WILL BE MORE CONSOLIDATED AT TIMES. AS IT HAS FOR DAYS...GFS LONG RANGE RUNS CONTINUE TO SHOW A SERIES OF POTENTIALLY SIGNIFICANT SRN STREAM SYSTEMS MOVING ACROSS THE CONUS THRU THE END OF THE MONTH. WHETHER ANY OF THESE SYSTEMS LIFT FAR ENOUGH N AND/OR PHASE WITH THE NRN STREAM TO BRING A SIGNIFICANT STORM SYSTEM INTO THE UPPER GREAT LAKES REMAINS TO BE SEEN. ONE THING THAT MAY EVENTUALLY FAVOR THE STORM TRACK PROGRESSIVELY SHIFTING NW WITH TIME ACROSS THE CONUS... ALLOWING SYSTEMS TO LIFT FARTHER N AND W FROM THE SRN ROCKIES...IS THE MJO WHICH HAS BEEN ACTIVE SINCE EARLY JAN. WHILE THE RECENT PHASE OF THE MJO HAS BEEN SUPPORTIVE OF COLDER WEATHER OVER THE GREAT LAKES...THAT WILL CHANGE OVER THE NEXT COUPLE OF WEEKS AS THE SHIFTING MJO PHASE BEGINS TO FAVOR RIDGING/WARMER CONDITIONS OVER THE ERN CONUS AND TROFFING/COLDER WEATHER OVER THE W. THIS WOULD AT LEAST SUPPORT A TENDENCY FOR ACTIVE SYSTEMS TO LIFT INTO THE GREAT LAKES LATER THIS MONTH. FOR UPPER MI...THE LONG TERM PORTION OF THE FCST TODAY STILL DOESN`T APPEAR TO OFFER ANY SIGNIFICANT SYSTEMS... BUT THERE WILL BE ONE TO WATCH JUST BEYOND THE TIME PERIOD OF THIS FCST AT THE END OF NEXT WEEK. BEHIND THE CLIPPER MOVING THRU THE GREAT LAKES TODAY...INFLUX OF ARCTIC AIR UNDERNEATH DEEPENING MID/UPPER TROF WILL LEAD TO LES THRU AT LEAST THE FIRST HALF OF THE WEEKEND. MODERATION WILL OCCUR BRIEFLY EARLY NEXT WEEK. THEN...A NEW TROF AMPLIFYING INTO THE CNTRL/ERN CONUS WILL BRING THE POTENTIAL FOR A PHASING SYSTEM OVER THE GREAT LAKES/ERN CONUS EARLY NEXT WEEK. HOW MUCH IMPACT THAT SYSTEM WILL HAVE OVER UPPER MI REMAINS TO BE SEEN. MID/UPPER LEVEL TROF WILL BE STEADILY DEEPENING OVER THE GREAT LAKES FRI/FRI NIGHT...AND WITH 850MB TEMPS AROUND -20C...LES WILL BE THE RULE DOWNWIND OF LAKE SUPERIOR. AT THE LOW-LEVELS...GENERAL NORTHWEST WINDS FRI WILL SHIFT A LITTLE MORE NORTHERLY FRI NIGHT. LAND BREEZES...ESPECIALLY FRI NIGHT/SAT MORNING...WILL HAVE SOME INFLUENCE ON THE WIND FIELD AND WILL SERVE TO FOCUS HEAVIER LES. INITIALLY...INVERSION FRI MORNING WILL BE AROUND 4-5KFT...BUT WILL STEADILY RISE UNDER DEEPENING MID LEVEL TROF...REACHING 8-10KFT FRI NIGHT. INVERSION MAY EVEN DISAPPEAR FOR A TIME FRI NIGHT PER GFS/NAM FCST SOUNDINGS AS TROF REACHES ITS DEEPEST OVER THE UPPER LAKES. SO...EXPECT A STEADY INCREASE IN LES INTENSITY FRI...AND THEN SNOW WILL PROBABLY BECOME HVY AT TIMES FRI NIGHT...IN PARTICULAR WHERE CONVERGENCE ZONES SET UP DUE TO LAND BREEZES. ALTHOUGH DGZ WILL BE PUSHED TOWARD THE SFC BY THE COLDER AIR OVER THE AREA...NAM FCST SOUNDINGS SHOW SUFFICIENT LAKE MODERATION TO KEEP DGZ AT LEAST IN THE LOWER PORTION OF THE CONVECTIVE LAYER. LONGER FETCH ACROSS THE E HALF OF LAKE SUPERIOR INTO NCNTRL UPPER MI SHOULD HELP KEEP DGZ HIGHER AND BETTER POSITIONED IN THE CONVECTIVE LAYER. AS A RESULT... EXPECT SNOW TO WATER RATIOS TO END UP AROUND 30 TO 1. AT THIS POINT...EXPECT ADVY LEVEL LES FOR THE MOST PART IN THE SNOWBELTS FAVORED BY NW WINDS FRI. SNOWFALL COULD THEN PUSH WARNING CRITERIA FRI NIGHT OVER GOGEBIC/ONTONAGON COUNTIES AND MORE SO OVER ALGER/NRN SCHOOLCRAFT COUNTIES AND PERHAPS FAR ERN MARQUETTE COUNTY DEPENDING ON HOW LAND BREEZE CONVERGENCE EVOLVES FRI NIGHT/SAT MORNING. SINCE POTENTIAL FOR WARNING AMOUNTS (8 INCHES OR MORE IN 12HRS OR 12 OR MORE IN 24HRS) IS FAIRLY HIGH FOR ALGER/NRN SCHOOLCRAFT...WILL ISSUE A LAKE EFFECT SNOW WATCH THERE FOR FRI THRU SAT MORNING. IN THE OTHER AREAS AFFECTED BY LES...ADVYS WILL PROBABLY WORK OUT. GIVEN THAT IT`S 3RD PERIOD...ESPECIALLY LATER 3RD PERIOD THAT SNOW REALLY PICKS UP...INTO A 4TH PERIOD EVENT...WILL NOT ISSUE ADVYS WITH THIS FCST ISSUANCE. SAT/SAT NIGHT...MID/UPPER TROF SHIFTS E AND SFC HIGH PRES RIDGE PUSHES INTO THE WRN GREAT LAKES. UNDER RISING HEIGHTS...INVERSIONS WILL FALL...RESULTING IN LES INTENSITY QUICKLY DIMINISHING W TO E. AS WINDS BACK W THEN SW SAT AFTN/SAT NIGHT...LINGERING LES WILL SHIFT...EVENTUALLY MOVING OUT OF THE FCST AREA...BUT PROBABLY NOT UNTIL LATE SAT NIGHT OVER THE NE. WITH A POTENTIAL PERIOD OF CLEAR SKIES/CALM WIND AS SFC HIGH PASSES OVER THE AREA SAT NIGHT...TEMPS COULD TANK. DROPPED MINS CONSIDERABLY FROM PREVIOUS FCST TO -10 TO -15F IN THE TRADITIONAL INTERIOR COLD SPOTS OVER THE W HALF. COULD BE SIMILAR READINGS OVER THE E IF CLEARING SPREADS THAT FAR E. IF THERE ENDS UP BEING SEVERAL HRS OF CLEAR SKIES/CALM WINDS...SOME TRADITIONAL COLD SPOTS MAY FALL BLO -20F. SUN...MID LEVEL RIDGE WILL BUILD INTO THE GREAT LAKES DOWNSTREAM OF NEXT TROF AMPLIFYING S INTO THE ROCKIES/WRN PLAINS. FAIRLY STRONG WAA PATTERN COULD LEAD TO SOME -SN SUN...BUT ECWMF/GFS HOLD STRONGEST WAA OFF TO THE W AND NW OF UPPER MI. SO...WILL PLAN FOR A DRY DAY SUN. TROF DIGGING INTO THE ROCKIES/WRN PLAINS SUN WILL SHIFT E...REACHING THE MISSISSIPPI VALLEY MON...THE GREAT LAKES TUE AND NEW ENGLAND WED. TROF TAKES ON A NEGATIVE TILT AFTER PASSING THE WRN GREAT LAKES...SO WOULD EXPECT THE MORE SIGNIFICANT PCPN WITH THE TROF TO BE E OF HERE. NONETHELESS...THERE COULD BE SOME ACCUMULATING SNOW AS THE SYSTEM PASSES ACROSS THE AREA MON...DEPENDING ON HOW QUICKLY THE ASSOCIATED SFC LOW ORGANIZES AND WHAT TRACK IT TAKES. RIGHT NOW...IT APPEARS THE SFC LOW WILL TRACK ACROSS UPPER MI WHICH SHOULD KEEP HEAVIER SNOW TO THE N OF HERE. HOWEVER...SINCE THIS SYSTEM IS SEVERAL DAYS OUT...INTENSITY/TRACK OF SYSTEM COULD CHANGE QUITE A BIT. WHAT IS MORE CERTAIN IS THAT ARCTIC AIR WILL AGAIN DUMP INTO THE UPPER LAKES MON NIGHT/TUE ON NORTHERLY WINDS...BRINGING ANOTHER ROUND OF LES DOWNWIND OF LAKE SUPERIOR. RAISED POPS WELL ABOVE CONSENSUS TO LIKELY/CATEGORICAL TO REFLECT THE GOOD RUN-TO-RUN CONSISTENCY OF MEDIUM RANGE GUIDANCE ON THE MAGNITUDE OF THE INCOMING COLD THAT WILL BE MUCH MORE THAN SUFFICIENT FOR LES. LES WILL GRADUALLY WIND DOWN WED AS TROF DEPARTS AND RIDGE BUILDS INTO THE UPPER MISSISSIPPI VALLEY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 639 AM EST THU FEB 14 2013 A LOW PRESSURE SYSTEM EXITING CENTRAL WISCONSIN THIS MORNING WILL PRODUCE LIGHT SNOW SHOWERS AT KSAW FOR THE FIRST COUPLE OF HOURS OF THE FORECAST. FOCUS THEN TURNS TO LAKE ENHANCED SNOW FOR A PERIOD TODAY...A BRIEF LULL DURING LATE AFTERNOON AND EARLY EVENING BEFORE LAKE EFFECT ARRIVES FOR NORTH-NORTHWEST WIND LOCATIONS. WILL CONTINUE IDEA OF LOWER VISIBILITIES AND CEILINGS WITH LAKE ENHANCED SNOW THROUGH THIS AFTERNOON AT ALL SITES. BUT AS THE LOW QUICKLY DEPARTS THIS AFTERNOON...SUPPORTING DEEP MOISTURE DEPARTS AND EXPECT WEAKENING SNOW SHOWERS INTO THE EVENING. BUT WITH COLDER AIR INCREASING THROUGH THE NIGHT...SHOULD SEE LAKE EFFECT SNOW INTENSIFY AT KIWD/KCMX THROUGH THE NIGHT. KSAW ON THE OTHER HAND WON/T SEE TOO FAVORABLE WIND DIRECTIONS AND HAVE JUST WENT WITH MVFR CEILINGS. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 448 AM EST THU FEB 14 2013 A LOW PRESSURE SYSTEM MOVING THROUGH WISCONSIN THIS MORNING WILL SHIFT EAST TO QUEBEC TONIGHT AND LEAD TO INCREASING NORTHERLY WINDS THIS AFTERNOON. EXPECT MOST LOCATIONS TO BE IN THE 20-30KT RANGE...BUT THERE COULD BE A FEW GALE FORCE GUSTS TO 35 KNOTS OVER THE CENTRAL PART OF LAKE SUPERIOR. COLDER AIR AND PERSISTENT NORTH TO NORTHWEST WINDS TONIGHT INTO SATURDAY MORNING WILL LEAD TO HEAVY FREEZING SPRAY AND HAVE ISSUED A HEAVY FREEZING SPRAY WARNING FOR PORTIONS OF LAKE SUPERIOR. HIGH PRESSURE WILL THEN BUILD IN ON SATURDAY AND SUNDAY FROM THE NORTHERN PLAINS AND DECREASE THE WINDS BELOW 15KTS. THEN AS A LOW PRESSURE SYSTEM APPROACHES LAKE SUPERIOR ON SUNDAY AND MOVES THROUGH ON MONDAY...EXPECT SOUTHERLY WINDS TO INCREASE TO 20-25KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW WATCH FROM FRIDAY MORNING THROUGH SATURDAY AFTERNOON FOR MIZ006-085. WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MIZ012. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING FROM 7 PM THIS EVENING TO 7 AM EST SATURDAY FOR LSZ264>266. LAKE MICHIGAN... NONE. && $$ SHORT TERM...SRF LONG TERM...ROLFSON AVIATION...SRF MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
449 AM EST THU FEB 14 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 448 AM EST THU FEB 14 2013 ATTENTION INITIALLY THIS MORNING IS ON THE LOW TRACKING THROUGH WISCONSIN THAT WILL TRACK TO THE EAST-NORTHEAST AND INTO NORTHERN LOWER MICHIGAN THIS MORNING. FORTUNATELY...MODELS HAVE COME INTO MUCH BETTER AGREEMENT ON THE TRACK OF THIS LOW FROM 24 HOURS AGO. STRONG SHORTWAVE NOTED ON WV IMAGERY IN SOUTHWEST WISCONSIN WITH A SECONDARY WAVE UPSTREAM IN NORTH DAKOTA. THIS SECONDARY WAVE WILL BE THE ONE THAT AMPLIFIES THE TROUGH OVER THE GREAT LAKES AND LEADS TO BELOW NORMAL TEMPERATURES AND LAKE EFFECT FOR TONIGHT INTO SATURDAY. BOTH THE LOW AND SHORTWAVE HAVE STARTED TO SHIFT MORE TO THE EAST IN THE LAST HOUR OR TWO...AS THE MODELS HAVE SHOWN. THIS LEADS TO A LITTLE MORE CONFIDENCE ON THE TRACK OF THE LOW AND ASSOCIATED PRECIPITATION ON THE NORTH SIDE FOR THIS MORNING. FAIRLY BROAD AREA OF LIGHT TO MODERATE SNOW ACROSS CENTRAL AND NORTHEAST WISCONSIN AS OF 4AM...WITH LIGHT SNOW OVER SOUTH CENTRAL UPPER MICHIGAN. USING LATEST RADAR DATA...IT APPEARS THIS STRONGEST PRECIPITATION IS TIED TO THE 900-800MB FGEN AND FN CONVERGENCE...WITH THE BROAD AREA OF LIGHT SNOW IN THE 750-650MB FGEN/Q-VECTOR CONV. TRACKING THIS TO THE EAST-NORTHEAST WITH THE LATEST RAP AND GFS/NAM...WOULD EXPECT THE LIGHT SNOW TO SLIDE ACROSS LOCATIONS SOUTHEAST OF WATERSMEET TO GWINN TO SENEY THROUGH THE MORNING HOURS. THE HEAVIEST SNOW SHOULD FOCUS OVER THE SOUTHERN HALF/THIRD OF MENOMINEE COUNTY FROM 12-17Z. 00Z NAM ACTUALLY KEPT THAT BEST FGEN AREA JUST SOUTH OF THE CWA...BUT THE 06Z RUN AND LATEST RAP/HRRR WOULD SUPPORT THE BEST SNOW ALONG AND SOUTH OF A LINE FROM ATHELSTANE WISCONSIN...TO BAGLEY...TO THE MENOMINEE/DELTA COUNTY LINE. SNOW RATIOS SHOULD BE AROUND 13 TO 1 WITH THE NARROW DGZ AND MUCH OF THE LOWER LEVEL FORCING AT OR BELOW THE DGZ. THUS...WITH QPF AMOUNTS TOWARDS 0.25-0.35 IN THAT HEAVIEST BAND...WOULD EXPECT THE SOUTHERN HALF OF MENOMINEE COUNTY TO SEE 2-4 INCHES OF SNOW. THE CITY OF MENOMINEE WOULD HAVE THE BEST OPPORTUNITY FOR SLIGHTLY HIGHER AMOUNTS TOWARDS 5 INCHES...DEPENDING ON WHERE THAT HEAVIEST BAND TRACKS THROUGH NORTHEAST WISCONSIN. WILL LEAVE THE ADVISORY AS IS SINCE THINKS LOOK TO BE IN DECENT SHAPE WITH THE TRACK OF THE HEAVIEST PRECIPITATION AND TIMING. ONE FINAL NOTE...THE RAP/HRRR DO BRING SOME OF THE HEAVIER SNOW INTO FAR SOUTHERN DELTA/SCHOOLCRAFT COUNTIES FOR LOCATIONS RIGHT ALONG LAKE MICHIGAN...BUT WILL WAIT TO SEE HOW THINGS EVOLVED BEFORE ISSUING AN SPS. AS THIS LOW SHIFTS TO THE EAST...EXPECT NORTHWESTERLY FLOW TO SLOWLY DROP 850MB TEMPS TOWARDS -17C BY 00Z FRIDAY. WITH LAKE SUPERIOR TEMPS IN THE 1-2C RANGE...EXPECT LAKE SOME LAKE ENHANCEMENT FOR THE FIRST PART OF THE DAY IN NORTHERLY WIND FAVORED LOCATIONS OVER THE WEST AND NORTH CENTRAL. THIS WILL TRANSITION TO PURE LAKE EFFECT BY EVENING AS THE DEEPER MOISTURE DEPARTS AND DELTA-T VALUES PUSH TOWARDS 18. EVEN THOUGH CONDITIONS BECOME FAVORABLE THIS EVENING AND THROUGH THE NIGHT...THERE IS SOME CONCERN IN THE AMOUNT OF SNOW THAT WILL FALL. THIS IS DUE TO THE DRY AIR WORKING IN BEHIND THE LOW...WHICH WILL KEEP INVERSION HEIGHTS TOWARD 5KFT OR EVEN LOWER IF OUR LOCAL WRF RUNS ARE CORRECT. A LINGERING TROUGH OVER THE EASTERN LAKE FROM THE LOW WILL LEAD TO WINDS OUT OF THE NNW TONIGHT AND HAVE FOLLOWED LOCAL CLIMATOLOGY POPS. EXPECT THE LAKE EFFECT TO BE BEST TONIGHT OVER THE WEST FIRST...ESPECIALLY TOWARDS WESTERN GOGEBIC/ONTONAGON COUNTIES WHERE THERE IS A SLIGHTLY LONGER FETCH AND THEN INCREASING OVERNIGHT OVER THE EAST AS THE COLDER AIR ARRIVES AND PUSHES THE CLOUD IN THE DGZ. LAKE ENHANCEMENT TODAY SHOULD HAVE LOWER SNOW RATIOS...IN THE MID TEENS...BUT AS THE COLDER AIR ARRIVES TONIGHT MUCH OF THE CLOUD WILL BE WITHIN THE DGZ AND EXPECT RATIOS TO RISE TOWARDS 30-1 BY FRIDAY MORNING. WOULD THINK THE VERY FLUFFY NATURE OF THE SNOW WILL TRY TO OFFSET THE LOWER INVERSION HEIGHTS AND STILL PUSH VALUES TOWARDS LOW END ADVISORY AMOUNTS BY FRIDAY MORNING IN THE LONGER FETCH AREAS...GOGEBIC/ONTONAGON/ALGER. SINCE IT WILL MAINLY BE DURING THE OVERNIGHT HOURS AND LIMITED IMPACT WITH THE FLUFFINESS...WILL NOT ISSUE AN ADVISORY AT THIS POINT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 448 AM EST THU FEB 14 2013 AN ACTIVE PATTERN WILL BE THE RULE ACROSS THE CONUS THRU THE LONG TERM AND PROBABLY RIGHT THRU THE END OF THE MONTH. SPLIT FLOW WILL GENERALLY DOMINATE WITH AN ENERGETIC SRN STREAM THOUGH FLOW WILL BE MORE CONSOLIDATED AT TIMES. AS IT HAS FOR DAYS...GFS LONG RANGE RUNS CONTINUE TO SHOW A SERIES OF POTENTIALLY SIGNIFICANT SRN STREAM SYSTEMS MOVING ACROSS THE CONUS THRU THE END OF THE MONTH. WHETHER ANY OF THESE SYSTEMS LIFT FAR ENOUGH N AND/OR PHASE WITH THE NRN STREAM TO BRING A SIGNIFICANT STORM SYSTEM INTO THE UPPER GREAT LAKES REMAINS TO BE SEEN. ONE THING THAT MAY EVENTUALLY FAVOR THE STORM TRACK PROGRESSIVELY SHIFTING NW WITH TIME ACROSS THE CONUS... ALLOWING SYSTEMS TO LIFT FARTHER N AND W FROM THE SRN ROCKIES...IS THE MJO WHICH HAS BEEN ACTIVE SINCE EARLY JAN. WHILE THE RECENT PHASE OF THE MJO HAS BEEN SUPPORTIVE OF COLDER WEATHER OVER THE GREAT LAKES...THAT WILL CHANGE OVER THE NEXT COUPLE OF WEEKS AS THE SHIFTING MJO PHASE BEGINS TO FAVOR RIDGING/WARMER CONDITIONS OVER THE ERN CONUS AND TROFFING/COLDER WEATHER OVER THE W. THIS WOULD AT LEAST SUPPORT A TENDENCY FOR ACTIVE SYSTEMS TO LIFT INTO THE GREAT LAKES LATER THIS MONTH. FOR UPPER MI...THE LONG TERM PORTION OF THE FCST TODAY STILL DOESN`T APPEAR TO OFFER ANY SIGNIFICANT SYSTEMS... BUT THERE WILL BE ONE TO WATCH JUST BEYOND THE TIME PERIOD OF THIS FCST AT THE END OF NEXT WEEK. BEHIND THE CLIPPER MOVING THRU THE GREAT LAKES TODAY...INFLUX OF ARCTIC AIR UNDERNEATH DEEPENING MID/UPPER TROF WILL LEAD TO LES THRU AT LEAST THE FIRST HALF OF THE WEEKEND. MODERATION WILL OCCUR BRIEFLY EARLY NEXT WEEK. THEN...A NEW TROF AMPLIFYING INTO THE CNTRL/ERN CONUS WILL BRING THE POTENTIAL FOR A PHASING SYSTEM OVER THE GREAT LAKES/ERN CONUS EARLY NEXT WEEK. HOW MUCH IMPACT THAT SYSTEM WILL HAVE OVER UPPER MI REMAINS TO BE SEEN. MID/UPPER LEVEL TROF WILL BE STEADILY DEEPENING OVER THE GREAT LAKES FRI/FRI NIGHT...AND WITH 850MB TEMPS AROUND -20C...LES WILL BE THE RULE DOWNWIND OF LAKE SUPERIOR. AT THE LOW-LEVELS...GENERAL NORTHWEST WINDS FRI WILL SHIFT A LITTLE MORE NORTHERLY FRI NIGHT. LAND BREEZES...ESPECIALLY FRI NIGHT/SAT MORNING...WILL HAVE SOME INFLUENCE ON THE WIND FIELD AND WILL SERVE TO FOCUS HEAVIER LES. INITIALLY...INVERSION FRI MORNING WILL BE AROUND 4-5KFT...BUT WILL STEADILY RISE UNDER DEEPENING MID LEVEL TROF...REACHING 8-10KFT FRI NIGHT. INVERSION MAY EVEN DISAPPEAR FOR A TIME FRI NIGHT PER GFS/NAM FCST SOUNDINGS AS TROF REACHES ITS DEEPEST OVER THE UPPER LAKES. SO...EXPECT A STEADY INCREASE IN LES INTENSITY FRI...AND THEN SNOW WILL PROBABLY BECOME HVY AT TIMES FRI NIGHT...IN PARTICULAR WHERE CONVERGENCE ZONES SET UP DUE TO LAND BREEZES. ALTHOUGH DGZ WILL BE PUSHED TOWARD THE SFC BY THE COLDER AIR OVER THE AREA...NAM FCST SOUNDINGS SHOW SUFFICIENT LAKE MODERATION TO KEEP DGZ AT LEAST IN THE LOWER PORTION OF THE CONVECTIVE LAYER. LONGER FETCH ACROSS THE E HALF OF LAKE SUPERIOR INTO NCNTRL UPPER MI SHOULD HELP KEEP DGZ HIGHER AND BETTER POSITIONED IN THE CONVECTIVE LAYER. AS A RESULT... EXPECT SNOW TO WATER RATIOS TO END UP AROUND 30 TO 1. AT THIS POINT...EXPECT ADVY LEVEL LES FOR THE MOST PART IN THE SNOWBELTS FAVORED BY NW WINDS FRI. SNOWFALL COULD THEN PUSH WARNING CRITERIA FRI NIGHT OVER GOGEBIC/ONTONAGON COUNTIES AND MORE SO OVER ALGER/NRN SCHOOLCRAFT COUNTIES AND PERHAPS FAR ERN MARQUETTE COUNTY DEPENDING ON HOW LAND BREEZE CONVERGENCE EVOLVES FRI NIGHT/SAT MORNING. SINCE POTENTIAL FOR WARNING AMOUNTS (8 INCHES OR MORE IN 12HRS OR 12 OR MORE IN 24HRS) IS FAIRLY HIGH FOR ALGER/NRN SCHOOLCRAFT...WILL ISSUE A LAKE EFFECT SNOW WATCH THERE FOR FRI THRU SAT MORNING. IN THE OTHER AREAS AFFECTED BY LES...ADVYS WILL PROBABLY WORK OUT. GIVEN THAT IT`S 3RD PERIOD...ESPECIALLY LATER 3RD PERIOD THAT SNOW REALLY PICKS UP...INTO A 4TH PERIOD EVENT...WILL NOT ISSUE ADVYS WITH THIS FCST ISSUANCE. SAT/SAT NIGHT...MID/UPPER TROF SHIFTS E AND SFC HIGH PRES RIDGE PUSHES INTO THE WRN GREAT LAKES. UNDER RISING HEIGHTS...INVERSIONS WILL FALL...RESULTING IN LES INTENSITY QUICKLY DIMINISHING W TO E. AS WINDS BACK W THEN SW SAT AFTN/SAT NIGHT...LINGERING LES WILL SHIFT...EVENTUALLY MOVING OUT OF THE FCST AREA...BUT PROBABLY NOT UNTIL LATE SAT NIGHT OVER THE NE. WITH A POTENTIAL PERIOD OF CLEAR SKIES/CALM WIND AS SFC HIGH PASSES OVER THE AREA SAT NIGHT...TEMPS COULD TANK. DROPPED MINS CONSIDERABLY FROM PREVIOUS FCST TO -10 TO -15F IN THE TRADITIONAL INTERIOR COLD SPOTS OVER THE W HALF. COULD BE SIMILAR READINGS OVER THE E IF CLEARING SPREADS THAT FAR E. IF THERE ENDS UP BEING SEVERAL HRS OF CLEAR SKIES/CALM WINDS...SOME TRADITIONAL COLD SPOTS MAY FALL BLO -20F. SUN...MID LEVEL RIDGE WILL BUILD INTO THE GREAT LAKES DOWNSTREAM OF NEXT TROF AMPLIFYING S INTO THE ROCKIES/WRN PLAINS. FAIRLY STRONG WAA PATTERN COULD LEAD TO SOME -SN SUN...BUT ECWMF/GFS HOLD STRONGEST WAA OFF TO THE W AND NW OF UPPER MI. SO...WILL PLAN FOR A DRY DAY SUN. TROF DIGGING INTO THE ROCKIES/WRN PLAINS SUN WILL SHIFT E...REACHING THE MISSISSIPPI VALLEY MON...THE GREAT LAKES TUE AND NEW ENGLAND WED. TROF TAKES ON A NEGATIVE TILT AFTER PASSING THE WRN GREAT LAKES...SO WOULD EXPECT THE MORE SIGNIFICANT PCPN WITH THE TROF TO BE E OF HERE. NONETHELESS...THERE COULD BE SOME ACCUMULATING SNOW AS THE SYSTEM PASSES ACROSS THE AREA MON...DEPENDING ON HOW QUICKLY THE ASSOCIATED SFC LOW ORGANIZES AND WHAT TRACK IT TAKES. RIGHT NOW...IT APPEARS THE SFC LOW WILL TRACK ACROSS UPPER MI WHICH SHOULD KEEP HEAVIER SNOW TO THE N OF HERE. HOWEVER...SINCE THIS SYSTEM IS SEVERAL DAYS OUT...INTENSITY/TRACK OF SYSTEM COULD CHANGE QUITE A BIT. WHAT IS MORE CERTAIN IS THAT ARCTIC AIR WILL AGAIN DUMP INTO THE UPPER LAKES MON NIGHT/TUE ON NORTHERLY WINDS...BRINGING ANOTHER ROUND OF LES DOWNWIND OF LAKE SUPERIOR. RAISED POPS WELL ABOVE CONSENSUS TO LIKELY/CATEGORICAL TO REFLECT THE GOOD RUN-TO-RUN CONSISTENCY OF MEDIUM RANGE GUIDANCE ON THE MAGNITUDE OF THE INCOMING COLD THAT WILL BE MUCH MORE THAN SUFFICIENT FOR LES. LES WILL GRADUALLY WIND DOWN WED AS TROF DEPARTS AND RIDGE BUILDS INTO THE UPPER MISSISSIPPI VALLEY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1222 AM EST THU FEB 14 2013 CMX/IWD...EXPECT MVFR CONDITIONS TO PREDOMINATE AT THESE LOCATIONS THRU THIS MRNG WITH AREA OF HEAVIER SN ON NRN FLANK OF CLIPPER LO MOVING INTO WI REMAINING TO THE S. AS COLDER AIR ARRIVES THIS AFTN ON THE HEELS OF A GUSTY NNW WIND...EXPECT SOME LES TO DVLP WITH VSBY FALLING TO IFR UNDER SOME OF THE HEAVIER SHSN...ESPECIALLY AT IWD WITH LONGER FETCH/MORE FVRBL UPSLOPE FLOW. SAW...EVEN THOUGH HEAVIER SN ASSOCIATED WITH CLIPPER LO MOVING THRU WI WL REMAIN TO THE S...EXPECT IFR CONDITIONS TO PREDOMINATE THRU THIS MRNG WITH UPSLOPE NNE FLOW OFF LK SUP BRINGING LO CLDS/SOME -SN. CONDITIONS WL IMPROVE TO MVFR LATER TDAY AS THE FLOW BACKS SUFFICIENTLY TO A DOWNSLOPING NNW FLOW. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 448 AM EST THU FEB 14 2013 A LOW PRESSURE SYSTEM MOVING THROUGH WISCONSIN THIS MORNING WILL SHIFT EAST TO QUEBEC TONIGHT AND LEAD TO INCREASING NORTHERLY WINDS THIS AFTERNOON. EXPECT MOST LOCATIONS TO BE IN THE 20-30KT RANGE...BUT THERE COULD BE A FEW GALE FORCE GUSTS TO 35 KNOTS OVER THE CENTRAL PART OF LAKE SUPERIOR. COLDER AIR AND PERSISTENT NORTH TO NORTHWEST WINDS TONIGHT INTO SATURDAY MORNING WILL LEAD TO HEAVY FREEZING SPRAY AND HAVE ISSUED A HEAVY FREEZING SPRAY WARNING FOR PORTIONS OF LAKE SUPERIOR. HIGH PRESSURE WILL THEN BUILD IN ON SATURDAY AND SUNDAY FROM THE NORTHERN PLAINS AND DECREASE THE WINDS BELOW 15KTS. THEN AS A LOW PRESSURE SYSTEM APPROACHES LAKE SUPERIOR ON SUNDAY AND MOVES THROUGH ON MONDAY...EXPECT SOUTHERLY WINDS TO INCREASE TO 20-25KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW WATCH FROM FRIDAY MORNING THROUGH SATURDAY AFTERNOON FOR MIZ006-085. WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MIZ012. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING FROM 7 PM THIS EVENING TO 7 AM EST SATURDAY FOR LSZ264>266. LAKE MICHIGAN... NONE. && $$ SHORT TERM...SRF LONG TERM...ROLFSON AVIATION...KC MARINE...SRF
AREA FORECAST DISCUSSION
NWS JACKSON MS
910 PM CST FRI FEB 15 2013 .UPDATE...LATEST SURFACE ANALYSIS HAS THE COLD FRONT SOUTH OF OUR CWA WITH HIGH PRESSURE CENTERED OVER THE PLAINS. THE PRESSURE GRADIENT AROUND THE HIGH WILL KEEP A COOL NORTH WIND OVER OUR AREA THROUGH THE NIGHT. WATER VAPOR IMAGERY/RUC ANALYSIS HAS THE UPPER LEVEL TROUGH AXIS SWINGING THROUGH THE SOUTHERN PLAINS. VERY COLD AIR WAS ASSOCIATED WITH THE TROUGH INCLUDING TEMPS COOLER THAN -30C AT 50H. RUC ANALYSIS WAS SHOWING THE 850MB ZERO DEGREE ISOTHERM NEAR A NATCHEZ TO JACKSON TO MACON LINE. THIS WAS COLLOCATED WITH A BAND OF MID LEVEL CLOUDS THAT LOCAL RADARS SUGGEST MAY DROP A FEW SPRINKLES AT TIMES. NORTHWEST OF THIS BAND OVER OUR DELTA REGION ONLY A FEW HIGH THIN CIRRUS CLOUDS WERE NOTED. LOOKING AT THE 00Z JAN SOUNDING AND RUC ANALYSIS HAVE DECIDED TO REMOVE ANY MENTION OF FLURRIES TONIGHT. ANY WET BULB COOLING AFFECTS SHOULD BE NORTH OF THE SPRINKLES. THE BAND OF MID LEVEL CLOUDS WILL CONTINUE TO GRADUALLY SHIFT SOUTHEAST THROUGH THE NIGHT. IT WILL BE COLDER TONIGHT WITH MORNING LOWS AT OR BELOW FREEZING OVER THE NORTHERN THIRD OF THE AREA. OUR SOUTHEAST MOST ZONES MAY BOTTOM OUT NEAR 40 DEGREES BUT MOST OF THE AREA WILL BE IN THE 30S AT DAYBREAK. /22/ && .AVIATION...NW WINDS OF 5-6KTS WILL CONTINUE TONIGHT. NW WINDS WILL INCREASE SATURDAY TO 10-15KTS WITH GUSTS OF 20KTS BY 17Z. OTHERWISE...VFR CONDS WILL PERSIST THROUGH SATURDAY NIGHT. /22/ && .PREV DISCUSSION... /ISSUED 405 PM CST FRI FEB 15 2013/ DISCUSSION...IT HAS TURNED OUT TO BE A RATHER PLEASANT DAY ACROSS A GOOD PORTION OF THE REGION...DESPITE A COLD FRONT PUSHING THROUGH THE HEART OF THE LOWER MISSISSIPPI VALLEY. THIS FRONT HAS BEEN ACCOMPANIED BY A FEW CLOUDS FROM TIME TO TIME...BUT THE THICKEST CLOUDS HAVE ONLY STARTED MOVING INTO WESTERN AND NORTHWEST ZONES IN THE PAST FEW YOURS. THESE CLOUDS COULD BEGIN PRODUCING SOME SPRINKLES AND PERHAPS EVEN A LIGHT SHOWER OR TWO TONIGHT ACROSS OUR REGION DUE TO COMBINATION OF LIFT FROM LOW LEVEL COLD AIR ADVECTION AND THE PROXIMITY OF A LARGE UPPER TROUGH OF LOW PRESSURE. PRECIP SHOULD NOT BE AT ALL HEAVY (IF YOU INDEED GET IT) DUE TO LACK OF MOISTURE AND CYCLOGENESIS. A LARGER STICKING POINT IS WHETHER OR NOT TO INCLUDE MENTION OF SNOW FLURRIES IN THE FORECAST BECAUSE PROGGED COLUMN TEMPS SUGGEST LEAST A MIX OF A FEW WET AND SMALL SNOWFLAKES LATE TONIGHT FOR AREAS ROUGHLY ALONG THE I-20 CORRIDOR AND NORTHEAST TOWARD THE GOLDEN TRIANGLE. IF SOME FLAKES DO FLY IN A FEW OF THESE AREAS IT SHOULD TRULY BE QUITE LIGHT AND THUS INCAPABLE OF STICKING TO SURFACES SINCE GROUND TEMPS IN AREAS AFFECTED SHOULD BE ABOVE FREEZING. THE POTENTIAL PROSPECT FOR ANOTHER SNOWFLAKE OR TWO (MIXED WITH RAIN SHOWERS) WILL REMAIN FOR LOCATIONS UP NEAR THE HIGHWAY 82 CORRIDOR THROUGH THE FIRST HALF OF THE DAY TOMORROW. THE MECHANISM FOR THIS LITTLE BIT OF LOW LEVEL CONVECTIVE SHOWERS WILL BE MINOR AND GROWING MORE INSIGNIFICANT THROUGHOUT THE DAY SINCE THE PREVIOUSLY-MENTIONED UPPER TROUGH AXIS WILL BE PULLING OFF TO THE EAST. OTHERWISE... ANTICIPATE PARTLY CLOUDY SKIES AT WORST WITH A STIFF NORTHWEST BREEZE WORSENING THE AMBIENT CHILLS AS HIGHS RANGE FROM THE UPPER 40S TO MID 50S. THE TOMORROW NIGHT THROUGH SUNDAY PERIOD LOOKS TO REMAIN RATHER BENIGN AS SHORT WAVE RIDGING (AND ASSOCIATED SURFACE HIGH PRESSURE) TAKES SHAPE BEHIND THE DEPARTING TROUGH AND THE ENERGY COMING TOWARD THE REGION FOR MONDAY. TEMPERATURES WILL GENERALLY TREND A LITTLE COOLER THAN AVERAGE OVER THIS 36 HOUR PERIOD WITH POTENTIAL FOR A SOLID FREEZE (LOWS IN THE 20S) FOR MANY AREAS SATURDAY NIGHT OR REALLY EARLY SUNDAY. WENT WITH MAV GUIDANCE LOWS FOR NOW WITH LITTLE ADJUSTMENT. HOWEVER...MID LEVEL CLOUDS TRYING TO STREAM IN FROM THE NORTH MAY WORK TO LIMIT RADIATIONAL COOLING POTENTIAL NORTH OF I-20 SATURDAY NIGHT AND THEREFORE AT LEAST THESE LOCATIONS HAVE A LITTLE POSSIBILITY OF VERIFYING WARMER THAN ADVERTISED. SUNDAY INTO SUNDAY NIGHT WILL DEFINITELY BE WARMER THAN SATURDAY WITH WINDS TURNING AROUND TO THE SOUTH IN ADVANCE OF A QUICK-HITTING RAIN MAKER SLATED FOR THE START OF THE WORK WEEK. /BB/ PREV DISCUSSION... /ISSUED 438 AM CST FRI FEB 15 2013/ LONG TERM...THE LONG TERM WILL FEATURE TWO SYSTEMS...THE FIRST ARRIVING LATE MON AFTERNOON INTO MON NGT AND THE SECOND MORE POTENT SYSTEM FOR THU-THU NGT. FOR MON INTO MON NGT...A SOLID TROUGH WILL PROGRESS THROUGH THE CENTRAL CONUS AND HELP PUSH A COLD FRONT ACROSS THE REGION. IN ADVANCE OF THE SYSTEM...DEEPER MOISTURE WILL INCREASE AND SUPPORT HIGH RAIN CHANCES BY MON NGT. MODEL TRENDS ARE DEVELOPING PRECIP IN THE INCREASING WAA REGIME SOONER AND THUS WILL CONTINUE TO TREND UPWARD WITH POPS FOR LATE MON AFTERNOON. STILL...THE BEST COMBO OF CONVERGENCE AND LIFT WILL BE DURING THE MON NGT PERIOD. GUID DATA HAS BEEN ROCK SOLID ON TIMING AND CONTINUE TO STRONGLY SUPPORT PRECIP FOR THE NGT PERIOD. DUE TO THIS...HAVE INCREASED POPS TO CATEGORICAL. MODEL DATA DOES SHOW A BIT OF ELEVATED INSTABILITY... ENOUGH TO SUPPORT ISO TSRA AND HAVE WORDED THE WEATHER AS SUCH. AS FOR HEAVY RAIN POTENTIAL...THIS RISK SEEMS LOW AT THIS POINT DUE TO LACK OF HIGH QUALITY GULF MOISTURE BEING IN PLACE...THE LACK OF INSTABILITY(EFFICIENT DEEP CONVECTION) AND THE PROGRESSIVE NATURE OF THE RAIN AREA. THE AREA LOOKS TO SEE .5 TO 1.0 INCH OF PRECIP. WHILE THE REGION HAS BE EXCEPTIONALLY WET OF LATE...WE SHOULD BE ABLE TO HANDLE THIS SORT OF PRECIP. DUE TO THIS...WILL REMOVE THE MENTION OF HEAVY RAIN AND FLOODING POTENTIAL. I EXPECT MOST OF THE PRECIP TO BE OUT OF THE CWA STARTING THE TUE PERIOD. WILL HOLD ON TO SOME LOW END POPS ACROSS THE EAST FOR JUST THE FIRST COUPLE HRS...THEN DRY THINGS. THE AIRMASS FOR MID WEEK LOOKS TO BRING NORMAL TYPE CONDITIONS. AS FOR TEMPS...CONTINUED TO USE A BLEND OF THE GFS AND THE OTHER COOLER GUID DATA SETS. FOR LATE WEEK...MODELS CONTINUE TO ADVERTISE THE POTENTIAL FOR A POTENT SYSTEM. TIMING HAS BEEN QUITE GOOD AND CONSISTENT FOR BEING THIS FAR OUT. THE FOCUS HAS BEEN ON THU AND THU NGT FOR A ROUND OF STORMS TO IMPACT THE REGION. THE OVERALL SETUP LOOKS VERY SPRING LIKE AND SUPPORTIVE OF SEVERE WEATHER. DUE TO MODEL CONSISTENCY AND HIGHER CONFIDENCE THAN NORMAL FOR 6-7 DAYS OUT...WILL MENTION THE RISK FOR SEVERE STORMS DURING THIS TIME. /CME/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 35 50 28 62 / 18 3 1 0 MERIDIAN 35 51 26 60 / 18 6 1 1 VICKSBURG 34 52 27 64 / 17 2 0 0 HATTIESBURG 40 54 27 61 / 19 2 0 0 NATCHEZ 35 53 30 64 / 21 1 0 0 GREENVILLE 30 47 30 60 / 7 8 1 0 GREENWOOD 31 46 28 62 / 9 9 2 1 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ 22/BB/CME
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
529 PM CST Fri Feb 15 2013 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... Short Range (Tonight through Sunday)... Main weather concern for this period centers on the overnight period but confined to only the western third of the CWA. One last vorticity max/shortwave diving down the backside of a retreating broad upper trough will drop south-southeast across eastern NE passing just west of the MO/KS state line overnight. Satellite imagery and radar returns suggest two vorticity maxima...one moving into northeast NE and a second west of BIE. Features are best seen on NAM h7 prog. Scattered snow showers a bit more widespread than shown by NAM output while RAP looks too generous on qpf. Prefer blending the two model outputs which results in higher pops and expanding snow shield a bit more east. Moderately high liquid/snow ratios show potential for a narrow swath of 1+ inches of snow over the far western counties. Given the expected scattered coverage of the snow prefer keeping pops under the likely category for now. Snow will have exited the southwestern CWA by Saturday morning with clearing from north to south. Saturday will bring the start of a welcome warmup over the Plains which will quickly spread east...reaching into the western counties by the afternoon hours. A band of dense mid level clouds will spread from west to east Saturday night and herald the arrival of the deepening warm air advection zone. Still expecting a significant warmup on Sunday although there may be a tighter west to east gradient due as boundary layer winds take on a south-southeast direction which will limit the degree of warming further east. MJ Medium Range (Monday through Friday)... Next week continues to look very active, with two systems moving through the Plains on Monday night and again from Wednesday night through early Friday. The primary focus will be the significant system for Wednesday night through Thursday night, which has the potential to be a fairly major winter storm if the current track pans out. On Monday, a deep longwave trough will dive through the Central Plains, driving a surface cold front through the CWA during the daylight hours. A broad area of scattered rain showers will be possible along and ahead of the front, but amounts will be light as moisture return into the Plains will be quite limited. A brief mix with snow may be possible along our eastern border if any light precipitation can linger behind the surface boundary, but no snow accumulation is expected. By Wednesday night, a deep upper low will begin to eject out of the four corners region. As it moves eastward into the southern Plains, strong southerly flow will draw Gulf moisture into the system, which will combine with the existing Pacific moisture and enhance precipitation coverage and intensity as the system begins to lift northeast. All model solutions bring the elevated warm front into at least the southeastern two thirds of the CWA by Thursday morning but keep cold air lingering at the surface over almost the entirety of the area, indicating a potential for freezing rain in those areas. Since this is a deviation from previous forecasts, have started out with a slight chance for freezing rain on top of the primary rain/snow mix, but the probability for ice may need to be heightened if future forecasts look similar. As cold air wraps in behind the 850mb low, precipitation should change to all snow from west to east during the day on Thursday, becoming all snow and lifting out of the area after 00z Friday. Very preliminary snowfall totals range from more than 6 inches across the northern third of the forecast area where precipitation type is likely to be snow during the majority of the event, to 2-3 inches in west central and eastern parts of the CWA, then tapering to less than 2 inches in the far southwest where rain or freezing rain will be the predominant precipitation type during the majority of the event. With the consistency of model solutions, both temporally and between different model configurations, the overall potential for a winter storm is increasing. However, precipitation types and snowfall amounts are still somewhat uncertain and will need to be further refined, especially as this system heads onshore early next week. Laflin && .AVIATION... For the 00Z TAFs...Area of snow showers over southeast NE is tracking directly toward the STJ/MCI/MKC corridor and will affect all 3 terminals between 02Z and 06Z. The wave producing this activity is more robust than the one last night, and therefore expect it to hold together long enough to produce occl MVFR or IFR restrictions through this 4 hour period with some potential light accumulations on runways. Hawblitzel && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ WFO EAX
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
334 PM CST THU FEB 14 2013 .SHORT TERM... ISSUED AT 333 PM CST THU FEB 14 2013 (TONIGHT) SECONDARY COLD FRONT IS EXPECTED TO MOVE THROUGH THE CWFA BY AROUND MIDNIGHT. ALOFT...A FAIRLY STRONG 500-HPA SHORTWAVE TROUGH WILL PROVIDE FORCING FOR ASCENT AND HELP TO PRODUCE SOME LIGHT PRECIPITATION FOR CENTRAL AND NORTHERN SECTIONS OF THE AREA. NWP GUIDANCE HAVE NOT EXACTLY BEEN CONSISTENT WITH PLACEMENT OF QPF AXIS...INCLUDING HI-RES SHORT-TERM MODELS SUCH AS THE RAP/HRRR. THEREFORE...HAVE ELECTED TO KEEP CHANCE POPS IN AREAS WHERE BEST MID/UPPER LEVEL FORCING WILL BE LOCATED. OVERALL...STILL LOOKS LIKE A LIGHT QPF EVENT WITH A RAIN/SNOW MIX INITIALLY CHANGING OVER TO SNOW AS THE BOUNDARY LAYER COOLS SUFFICIENTLY. ACCUMULATIONS OF SNOWFALL ARE LIKELY TO BE ON THE ORDER OF A DUSTING TO A QUARTER OF AN INCH...THOUGH THESE NW FLOW "SYSTEMS" THIS WINTER HAVE NOT EXACTLY BEEN WELL BEHAVED. GOSSELIN && .LONG TERM... ISSUED AT 333 PM CST THU FEB 14 2013 (FRIDAY THROUGH SUNDAY) THE TAIL END OF THE SHORTWAVE SHOULD BE THROUGH MOST OF THE AREA BY 18Z THURSDAY. WILL KEEP SCATTERED FLURRIES GOING THROUGH THE MORNING HOURS UNTIL THE LAST OF THE ENERGY CLEARS THE AREA. CERTAINLY NOT EXPECTING ANY ADDITIONAL ACCUMULATION AS WE WILL BE WELL INTO COLD/DRY ADVECTION THROUGH THE LOWEST 10,000FT OF THE ATMOSPHERE AFTER 12Z. A COLD DRY AIRMASS DROPS ACROSS THE AREA AS ANOTHER SHORTWAVE DIPS DOWN THE BACKSIDE OF THE OVERALL TROF...DIGGING AND AMPLIFYING THE LONGWAVE INTO THE LOWER MISSISSIPPI VALLEY ON SATURDAY. NAM KICKS OUT SOME LIGHT QPF LATE FRIDAY NIGHT/EARLY SATURDAY MORNING AS THE SHORTWAVE RIPPLES BY...BUT THE GFS IS DRY AND THE LOCAL WRF MODEL KEEPS THE PRECIP OUT OF OUR AREA SO HAVE KEPT FORECAST DRY AT THIS TIME. THE AMPLIFIED LONGWAVE MOVES EAST SATURDAY NIGHT ALLOWING UPPER LEVEL RIDGING AND WARMER TEMPERATURES TO BUILD BACK INTO MISSOURI AND ILLINOIS ON SUNDAY. MOS GUIDANCE LOOKS VERY REASONABLE THROUGH THE PERIOD...SO HAVE USED A BLEND OF THE PREVIOUS FORECAST AND MOS FOR TEMPERATURES THROUGH SUNDAY. (MONDAY THROUGH THURSDAY) ANOTHER LONGWAVE TROF DEEPENS ACROSS THE ROCKY MOUNTAINS SUNDAY NIGHT INTO MONDAY. THIS WILL FORCE LEE-SIDE CYCLOGENESIS MONDAY...BUT JUST AS THE UPPER SYSTEM ISN`T A TIGHTLY COMPACTED SHORTWAVE...THE SURFACE SYSTEM WILL LIKEWISE BE AN ELONGATED TROF STRETCHING FROM SOUTHERN ONTARIO ALL THE WAY TO TEXAS. PLENTY OF MOISTURE CONVERGENCE IN THE WARM ADVECTION AHEAD OF THE TROF MONDAY SO HAVE INCREASED POPS TO LIKELY. AS THE SYSTEM WINDS UP OVER THE GREAT LAKES ON MONDAY NIGHT AND COLD ADVECTION REALLY RAMPS UP OVER THE AREA...THE RAIN MAY END AS A LITTLE LIGHT SNOW. TUESDAY AND WEDNESDAY LOOK PRETTY TRANQUIL AHEAD OF THE NEXT SYSTEM WITH SEASONABLY COOL TEMPERATURES...BUT THURSDAY LOOKS PRETTY INTERESTING. MEDIUM RANGE GUIDANCE IS REMARKABLY SIMILAR ON THURSDAY WITH A VERY STRONG SHORTWAVE MOVING OFF THE ROCKIES...GENERATING A CLOSED LOW THROUGH MOST OF THE DEPTH OF THE TROPOSPHERE. BOTH THE GFS AND ECMWF HAVE THE SURFACE LOW GENERALLY BETWEEN WICHITA AND TOPEKA...WHICH IS PRETTY DARN GOOD AGREEMENT THIS FAR OUT. RIGHT NOW...THE MOST LIKELY PRECIPITATION TYPE ACROSS THE AREA LOOKS LIKE A WET SLOPPY RAIN/SNOW MIX AS WE`LL BE ON THE NORTHEAST SIDE OF THE STORM...STILL IN THE COLD SECTOR. HOWEVER THIS COULD...AND LIKELY WILL CHANGE ABOUT A DOZEN TIMES BETWEEN NOW AND THEN. CARNEY && .AVIATION... ISSUED AT 1138 AM CST THU FEB 14 2013 VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THIS AFTERNOON AS UPPER-LEVEL IMPULSE RESPONSIBLE FOR BRINGING COLD FRONT THROUGH THE REGION EARLIER THIS MORNING STAYS FAR ENOUGH NORTH/NORTHEAST TO HAVE ALMOST NO IMPACT OTHER THAN WIND SHIFT TO THE WEST- NORTHWEST. DROPPED GUSTS AT TAF SITES WITH EXCEPTION OF KUIN AS HIGHER WINDS ALOFT WEAKEN WITH TIME. UPSTREAM OBSERVATIONS ALSO SUPPORT A BIT WEAKER WINDS AND WIND GUSTS THAN PREVIOUSLY THOUGHT. MID/HIGH LEVEL CLOUDINESS WILL STREAM IN THIS AFTERNOON FROM WEST TO EAST IN WNW FLOW ALOFT. MVFR CEILINGS ARE FORECAST TO MOVE SOUTHEASTWARD WITH TIME AND AFFECT TAF SITES OVERNIGHT AS A SECOND UPPER-LEVEL IMPULSE BRINGS A REINFORCING SHOT OF COLDER AIR ALONG WITH A CHANCE OF LIGHT SNOW. BEST CHANCES OF LIGHT SNOW ATTM LOOK TO BE ORIENTED WEST- EAST ORIENTED NEAR INTERSTATE 70. THIS SCENARIO IS SUPPORTED BY LAST FEW RUNS OF RAP GUIDANCE WHICH HAS PERFORMED QUITE WELL THIS WINTER...INCLUDING THE FEB. 2 SURPRISE SNOW WHICH CAME BENEATH NW FLOW ALOFT AS WELL. LOW CLOUDINESS WILL SCATTER OUT BY TOMORROW MORNING WITH WINDS VEERING TO THE NORTHWEST WITH SPEEDS BETWEEN 10 AND 15 MPH. SPECIFICS FOR KSTL... VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THIS AFTERNOON AS UPPER-LEVEL IMPULSE RESPONSIBLE FOR BRINGING COLD FRONT THROUGH THE REGION EARLIER THIS MORNING STAYS FAR ENOUGH NORTH/NORTHEAST TO HAVE NO IMPACT OTHER THAN WIND SHIFT TO THE WEST-NORTHWEST. DROPPED GUSTS AT LAMBERT AS HIGHER WINDS FROM ALOFT WEAKEN WITH TIME. UPSTREAM OBSERVATIONS ALSO SUPPORT A BIT WEAKER WINDS AND WIND GUSTS THAN PREVIOUSLY THOUGHT. MID/HIGH LEVEL CLOUDINESS WILL STREAM IN THIS AFTERNOON FROM WEST TO EAST IN WNW FLOW ALOFT. MVFR CEILINGS ARE FORECAST TO MOVE SOUTHEASTWARD WITH TIME AND AFFECT TAF SITES OVERNIGHT AS A SECOND UPPER-LEVEL IMPULSE BRINGS A REINFORCING SHOT OF COLDER AIR ALONG WITH A CHANCE OF LIGHT SNOW. BEST CHANCES OF LIGHT SNOW ATTM LOOK TO BE ORIENTED WEST-EAST ORIENTED NEAR INTERSTATE 70. THIS SCENARIO IS SUPPORTED BY LAST FEW RUNS OF RAP GUIDANCE WHICH HAS PERFORMED QUITE WELL THIS WINTER...INCLUDING THE FEB. 2 SURPRISE SNOW WHICH CAME BENEATH NW FLOW ALOFT AS WELL. LOW CLOUDINESS WILL SCATTER OUT BY TOMORROW MORNING WITH WINDS VEERING TO THE NORTHWEST WITH SPEEDS BETWEEN 10 AND 15 MPH. GOSSELIN && .PRELIMINARY POINT TEMPS/POPS... SAINT LOUIS 30 37 22 34 / 30 10 10 5 QUINCY 24 33 17 31 / 30 10 10 5 COLUMBIA 28 37 19 35 / 20 10 10 5 JEFFERSON CITY 29 37 20 35 / 20 10 10 5 SALEM 32 36 21 32 / 30 10 10 5 FARMINGTON 31 39 20 36 / 20 10 10 5 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1147 AM CST THU FEB 14 2013 .SHORT TERM... ISSUED AT 320 AM CST THU FEB 14 2013 (TODAY) FIRST IN A SERIES OF COLD FRONTS TO SLIDE THROUGH FORECAST AREA THIS MORNING WITH SOUTHWEST WINDS VEERING TO THE WEST AND PICKING UP. NOT A LOT OF CAA WITH THIS INITIAL FRONTAL BOUNDARY AND WITH DECENT MIXING TO 850 MB...SO SHOULD STILL SEE TEMPS WARM UP TODAY INTO THE UPPER 40S TO MID 50S. AS FOR THE WINDS...TO INCREASE TO 10 TO 20 MPH WITH GUSTS NEAR 30 MPH AT TIMES THIS AFTERNOON...ESPECIALLY OVER NORTHERN PORTIONS OF FORECAST AREA. BYRD && .LONG TERM... ISSUED AT 320 AM CST THU FEB 14 2013 (TONIGHT-SUNDAY) BEEN STRUGGLING ON WHAT TO DO WITH PRECIP POTENTIAL TONIGHT AS SECONDARY SHORTWAVE DROPS S AND DEEPENS TROF OVER THE CENTRAL U.S. 00Z NAM AND ASSOCIATED OUTPUT SUGGESTS VORT MAX WILL STAY RATHER WELL-DEFINED AS IT DIVES SE ACROSS THE AREA TONIGHT GENERATING LIGHT QPF OVER MOST OF THE REGION AND SUGGESTING SOME VERY MINOR SNOW ACCUMULATIONS. MEANWHILE...WHILE OTHER SOLUTIONS TEND TO FORECAST MORE OF A BROAD TROF...AND LESSER QPF...SWEEPING ACROSS THE AREA. NOT CERTAIN WHICH TREND IS MORE CORRECT...BUT AM A LITTLE CONCERNED THAT ALL SHORT RANGE SOLUTIONS DO INDICATE MID LEVEL LAPSE RATES GETTING FAIRLY STEEP OVERNIGHT. HAVE DECIDED TO ADD CHANCE POPS FOR MUCH OF THE AREA...SLOWLY SPREADING FROM N TO S DURING THE OVERNIGHT HOURS. GIVEN FORECAST SOUNDINGS IT CERTAINLY POSSIBLE THAT ANY PRECIP WOULD START AS A BIT OF LIGHT RAIN...BUT IF THERE IS ANY INTENSITY TO THE PRECIP THINK EVAP COOLING WILL QUICKLY COOL LOW LEVELS ENOUGH TO CHANGE THE RAIN TO SNOW. THE LEADING EDGE OF THE TRULY COLD AIR WILL ARRIVE LATER TONIGHT...AND DUE TO ITS LATE ARRIVAL MINS MAY STILL NOT BE TOO TERRIBLY COLD. HOWEVER...THE TEMPERATURE REBOUND ON FRIDAY SHOULD NOT BE MORE THAN 10 DEGREES DUE TO THE INTENSITY OF THE COLD AIR ADVECTION...EVEN WITH A FAIR AMOUNT OF AFTERNOON SUNSHINE. THE CAA IS FORECAST TO CONTINUE INTO THE START OF THE WEEKEND...AND A REINFORCING SHOT OF COLD AIR SHOULD ARRIVE FRIDAY NIGHT/SATURDAY MORNING AS A THIRD SHORTWAVE DIVES INTO THE AREA. WILL HAVE TO KEEP AN EYE ON THE PRECIP POTENTIAL WITH THIS FEATURE AS THE TRICKY N/NW FLOW PERSISTS OVER THE CENTRAL CONUS...BUT RIGHT NOW IT APPEARS MAIN DYNAMICS WOULD BE IMPACTING AREAS WEST OF OUR CWA. LOWEST TEMPERATURES OF THIS COLD SNAP SHOULD BE ON SATURDAY...WITH MORNING LOWS IN THE TEENS AND LOWER 20S AND HIGHS IN THE 30-35 DEGREE RANGE. 00Z RUNS CONTINUE TO SUPPORT IDEA THAT UA PATTERN WILL REMAIN QUITE PROGRESSIVE...TAKING CENTRAL CONUS TROF TO THE EAST COAST BY SUNDAY WHICH IN TURN WILL ALLOW A RAPID MODERATION IN TEMPERATURES OVER THE MID MISSISSIPPI VALLEY FOR THE LAST HALF OF THE WEEKEND. TEMPERATURES SHOULD CLIMB 15 DEGREES OR SO FROM SATURDAY`S HIGHS...AND RANGE FROM THE MID 40S OVER OUR E IL COUNTIES TO AROUND 50 OVER MID MO. (MONDAY-WEDNESDAY) MODEL TO MODEL AND RUN TO RUN AGREEMENT IN BROAD-SCALE SYNOPTIC FEATURES CONTINUES INTO THE FIRST HALF OF NEXT WEEK...WITH NEXT STRONG TROF PUSHING ACROSS AREA MONDAY AND MONDAY EVENING WITH FAIRLY GOOD RAIN POTENTIAL GIVEN MOISTURE ADVECTION INTO AREA AND STRONG DYNAMICS. ANOTHER ROUND OF BELOW NORMAL TEMPERATURES IS EXPECTED IN THE WAKE OF THIS SYSTEM ON TUESDAY AND WEDNESDAY. TRUETT && .AVIATION... ISSUED AT 1138 AM CST THU FEB 14 2013 VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THIS AFTERNOON AS UPPER-LEVEL IMPULSE RESPONSIBLE FOR BRINGING COLD FRONT THROUGH THE REGION EARLIER THIS MORNING STAYS FAR ENOUGH NORTH/NORTHEAST TO HAVE ALMOST NO IMPACT OTHER THAN WIND SHIFT TO THE WEST- NORTHWEST. DROPPED GUSTS AT TAF SITES WITH EXCEPTION OF KUIN AS HIGHER WINDS ALOFT WEAKEN WITH TIME. UPSTREAM OBSERVATIONS ALSO SUPPORT A BIT WEAKER WINDS AND WIND GUSTS THAN PREVIOUSLY THOUGHT. MID/HIGH LEVEL CLOUDINESS WILL STREAM IN THIS AFTERNOON FROM WEST TO EAST IN WNW FLOW ALOFT. MVFR CEILINGS ARE FORECAST TO MOVE SOUTHEASTWARD WITH TIME AND AFFECT TAF SITES OVERNIGHT AS A SECOND UPPER-LEVEL IMPULSE BRINGS A REINFORCING SHOT OF COLDER AIR ALONG WITH A CHANCE OF LIGHT SNOW. BEST CHANCES OF LIGHT SNOW ATTM LOOK TO BE ORIENTED WEST- EAST ORIENTED NEAR INTERSTATE 70. THIS SCENARIO IS SUPPORTED BY LAST FEW RUNS OF RAP GUIDANCE WHICH HAS PERFORMED QUITE WELL THIS WINTER...INCLUDING THE FEB. 2 SURPRISE SNOW WHICH CAME BENEATH NW FLOW ALOFT AS WELL. LOW CLOUDINESS WILL SCATTER OUT BY TOMORROW MORNING WITH WINDS VEERING TO THE NORTHWEST WITH SPEEDS BETWEEN 10 AND 15 MPH. SPECIFICS FOR KSTL... VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THIS AFTERNOON AS UPPER-LEVEL IMPULSE RESPONSIBLE FOR BRINGING COLD FRONT THROUGH THE REGION EARLIER THIS MORNING STAYS FAR ENOUGH NORTH/NORTHEAST TO HAVE NO IMPACT OTHER THAN WIND SHIFT TO THE WEST-NORTHWEST. DROPPED GUSTS AT LAMBERT AS HIGHER WINDS FROM ALOFT WEAKEN WITH TIME. UPSTREAM OBSERVATIONS ALSO SUPPORT A BIT WEAKER WINDS AND WIND GUSTS THAN PREVIOUSLY THOUGHT. MID/HIGH LEVEL CLOUDINESS WILL STREAM IN THIS AFTERNOON FROM WEST TO EAST IN WNW FLOW ALOFT. MVFR CEILINGS ARE FORECAST TO MOVE SOUTHEASTWARD WITH TIME AND AFFECT TAF SITES OVERNIGHT AS A SECOND UPPER-LEVEL IMPULSE BRINGS A REINFORCING SHOT OF COLDER AIR ALONG WITH A CHANCE OF LIGHT SNOW. BEST CHANCES OF LIGHT SNOW ATTM LOOK TO BE ORIENTED WEST-EAST ORIENTED NEAR INTERSTATE 70. THIS SCENARIO IS SUPPORTED BY LAST FEW RUNS OF RAP GUIDANCE WHICH HAS PERFORMED QUITE WELL THIS WINTER...INCLUDING THE FEB. 2 SURPRISE SNOW WHICH CAME BENEATH NW FLOW ALOFT AS WELL. LOW CLOUDINESS WILL SCATTER OUT BY TOMORROW MORNING WITH WINDS VEERING TO THE NORTHWEST WITH SPEEDS BETWEEN 10 AND 15 MPH. GOSSELIN && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS BILLINGS MT
856 PM MST FRI FEB 15 2013 .SHORT TERM...VALID FOR SAT AND SUN... WE INCREASED FORECAST LOWS BY A COUPLE DEGREES TONIGHT ACROSS MUCH OF THE AREA...BUT THAT WAS REALLY THE ONLY ADJUSTMENT OF NOTE WITH OUR EVENING UPDATE. MID-LEVEL WARM AIR ADVECTION IS BEGINNING THIS EVENING AS A 500-HPA RIDGE STARTS BUILDING IN FROM THE WEST. THERE HAVE BEEN SOME ECHOES ON RADAR IMAGERY OVER FAR EASTERN MT TIED TO WEAK FORCING ON ISENTROPIC SURFACES ALONG THE MID-LEVEL WARM FRONT THE LAST FEW HOURS...BUT AS OF 0345 UTC THERE HAVE BEEN NO REPORTS OF PRECIPITATION AT THE GROUND. EVEN SO...WE DECIDED TO MAINTAIN A SLIGHT CHANCE OF SNOW FOR BAKER THROUGH 06 UTC BASED ON THE 00 UTC NAM AND RECENT RAP SIMULATIONS. TEMPERATURES HAVE ONLY DROPPED OFF SLOWLY IN MANY AREAS THIS EVENING THANKS TO 1/ MID- AND HIGH-LEVEL CLOUDS...AND 2/ INCREASING WINDS ACROSS SOUTH CENTRAL MT WHILE LEE TROUGHING BECOMES ESTABLISHED. BASED ON THAT...WE UTILIZED THE NEW 00 UTC MET AND RECENT LAMP MOS TO RAISE LOWS A FEW DEGREES IN MANY AREAS. FINALLY...WINDS ARE ON THE INCREASE AT LIVINGSTON...AND THE 00 UTC NAM STILL CALLS FOR A PRESSURE GRADIENT OF AT LEAST 15 HPA BETWEEN IDAHO FALLS AND LEWISTOWN BY SAT MORNING. THUS...OUR WIND ADVISORY LOOKS ON TRACK. SCHULTZ .LONG TERM...VALID FOR MON...TUE...WED...THU...FRI... NO MAJOR CHANGES TO THE GOING FORECAST THIS AFTERNOON. UPPER TROF PUSHES THROUGH THE AREA ON MONDAY EXITING MONDAY NIGHT. CURRENT LOW POPS LOOK OK FOR SUNDAY NIGHT...BUT MAY NEED TO BUMP UP DAYTIME POPS MONDAY IF LATEST SOLUTION PERSIST. TEMPERATURES MONDAY WILL BE BELOW SEASONAL LEVELS...MAINLY IN THE 30S. TUESDAY BRINGS AN UPPER RIDGE TO THE AREA FOR MAINLY DRY CONDITIONS...THOUGH A BACKDOOR COLD FRONT COULD BRING SOME LIGHT SNOW/FLURRIES TO EASTERN ZONES. STRONG STORM SYSTEM TAKING SHAPE FOR WEDNESDAY INTO NEXT WEEKEND. SOUTHERLY DIFFLUENT FLOW WILL DEVELOP ON WEDNESDAY OVER THE AREA ON THE FRONT SIDE OF THE TROF. UPPER LOW THEN PUSHES OUT OF CALIFORNIA ON A NORTHEASTERLY TRAJECTORY INTO THE CENTRAL PLAINS BY THURSDAY...THEN PINWHEELS INTO THE NORTHERN PLAINS ON FRIDAY. MODELS DISAGREEING ON THE TRACK WITH THIS LOW...WHICH IS NOT UNCOMMON 5 TO 7 DAYS OUT. GFS GOES WELL SOUTH OF THE FOUR CORNERS WITH THE UPPER LOW BEFORE KICKING NORTH...WHILE THE ECMWF TAKES A PATH FROM LAS VEGAS TO GRAND JUNCTION. THE MORE NORTHERLY PATH WOULD KEEP MORE ENERGY AND MOISTURE ACROSS SOUTHERN MONTANA THAN THE FURTHER SOUTH SOLUTION. CURRENTLY HAVE TEMPERATURES WELL BELOW AVERAGE IN THE FORECAST FOR THIS PERIOD WHICH SEEMS REASONABLE GIVEN THE DEEP TROF OVER THE AREA. BROADBRUSH CHANCE TYPE PRECIPITATION CHANCES SEEM REASONABLE AS WELL. THIS TYPE OF SYSTEM CLIMATOLOGICALLY HAS A GOOD CHANCE TO PRODUCE SIGNIFICANT PRECIPITATION OVER THE AREA...ESPECIALLY SOUTHEAST MONTANA AND WILL BE WATCHED CLOSELY AS IT EVOLVES IN THE MODELS OVER THE NEXT FEW DAYS. CHAMBERS && .AVIATION... VFR CONDITIONS EXPECTED TONIGHT. WINDS OVER WESTERN FOOTHILLS LOCATIONS WILL INCREASE OVERNIGHT WITH GUSTS AROUND 40KTS EXPECTED. WIND GUSTS WILL INCREASE TO AROUND 50KTS BY SUNRISE IN THE LIVINGSTON TO BIG TIMBER TO NYE TRIANGLE. LOW LEVEL WIND SHEAR WILL EXIST OVERNIGHT FOR KMLS AND KSHR TAF LOCATIONS WITH WEST TO NORTHWEST WINDS AROUND 35KTS JUST OFF THE SURFACE. TWH && .PRELIMINARY POINT TEMP/POPS... SAT SUN MON TUE WED THU FRI ----------------------------------------------------------- BIL 029/052 030/044 021/032 014/028 013/024 010/027 014/033 00/N 16/W 42/J 11/B 34/S 42/S 22/S LVM 035/049 030/040 017/033 013/033 016/026 011/032 016/035 00/N 36/J 43/J 02/J 34/S 32/S 22/S HDN 024/048 025/041 019/030 009/028 013/026 006/027 008/032 00/U 16/J 52/J 11/B 24/S 42/S 22/S MLS 028/049 033/041 019/026 007/026 007/023 006/022 009/027 10/U 15/W 62/J 11/B 13/S 32/S 22/S 4BQ 025/046 027/041 019/027 008/027 011/026 007/020 008/028 10/U 03/J 62/J 11/B 14/S 42/S 22/S BHK 025/045 029/041 017/021 003/020 005/017 003/014 003/024 20/B 04/J 62/J 11/U 13/S 32/S 22/S SHR 019/045 020/038 017/029 008/030 015/027 005/024 007/033 00/U 04/J 63/J 11/B 25/S 52/S 22/S && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...WIND ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 9 AM MST SUNDAY FOR ZONES 65-66. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1100 PM MST Wed Feb 13 2013 .DISCUSSION... Update forthcoming. Cold front has pushed through the Great Falls area and areas of snow have developed behind the front. Radar indicating a couple of bands of snow located just north of Great Falls and moving northwest to southeast. This band is slowly sagging south. RUC analysis indicates heaviest snow should fall between now and midnight with snow tapering off after that. Have raised pops and snow amounts for portions of North Central Montana. Emanuel && .AVIATION... Updated 0600Z. A moist northwest flow aloft will continue over Montana through Thursday. Scattered showers can be expected around terrain across Central Montana through about 12z. Activity diminishes early morning over most of Montana before skies clear out a bit through the middle of the day. Expect mid and upper clouds to increase later afternoon Thursday before another possible round of evening showers. && .PREV DISCUSSION...Issued 248 PM MST Wed Feb 13 2013 Wednesday through Friday...Convective activity continues to develop and move across Central and North Central Montana with showers slowly moving southward into the Mountains of Southwest Montana. Convective activity should continue into the evening hours but diminish significantly by sunset when daytime heating no longer drives the thermal activity. Temperatures decrease back towards seasonal averages tonight behind the cold front. High temperatures will be limited as the cool air mass slowly moderates over the next 24 hours. Some moisture aloft will allow for the possibility of snow showers over the higher terrain through Thursday night...however no significant accumulations are expected...especially at the lower elevation. An upper level ridge will begin to move into the region by Friday and allow for drier and warmer conditions to again develop throughout the day...with temperatures rising back above seasonal averages. Suk Friday night through Wednesday night...Good consistency continues among the models for this period. An upper level ridge of high pressure building into Montana Friday night and Saturday will keep the area mostly dry and quite mild (10 to 15 degrees above normal - with highs on Saturday reaching into the 40s to lower 50s). A shortwave trough will flatten the ridge as it moves into the area from the Pacific Northwest coast on Saturday, bringing a chance of showers to the Rocky Mountain Front and increasing westerly downslope winds to the remainder of the area. This shortwave will then move southeast through the area Saturday night into Sunday with an associated Canadian cold front. The chance for precipitation will increase Saturday night, while models continue to bring widespread light snow to the area on Sunday. Have therefore increased the chance for precipitation a bit more through these periods. Temperatures will be quite cool with the frontal passage on Sunday, as highs will only reach into the upper 20s to mid 30s most areas. Forecast snowfall amounts are fairly light at this time (with most lower elevations only forecast to receive an inch or 2 of snow). However, this situation will continue to be monitored for potential winter weather highlights, as the warm-up prior to the snow may warm pavement enough that initially melting snow may refreeze with the passage of the cold front, causing icy roadways. This may become a situation similar to that from this past weekend. An upper level ridge of high pressure will then follow this system into the state Sunday night through Monday night, allowing temperatures to warm back closer to normal with a decreasing chance of snow. A deep upper level trough of low pressure will then move across the western CONUS Tuesday night through Wednesday. The trough is forecast to split somewhat, with the southern portion taking the bulk of the energy south of the area. Despite this, a low level easterly flow may bring enough moisture into the southern half of the state to allow a good chance of snow to develop across central/southwest Montana. Coulston && .PRELIMINARY POINT TEMPS/POPS... GTF 21 35 21 42 / 100 10 10 10 CTB 16 34 21 41 / 30 10 10 10 HLN 25 35 22 40 / 40 30 20 10 BZN 20 31 16 36 / 60 40 30 10 WEY 10 24 6 29 / 60 30 40 10 DLN 20 32 17 37 / 30 30 20 10 HVR 10 27 9 31 / 20 10 10 10 LWT 16 28 14 34 / 100 30 10 10 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
910 PM MST Wed Feb 13 2013 .DISCUSSION... Update forthcoming. Cold front has pushed through the Great Falls area and areas of snow have developed behind the front. Radar indicating a couple of bands of snow located just north of Great Falls and moving northwest to southeast. This band is slowly sagging south. RUC analysis indicates heaviest snow should fall between now and midnight with snow tapering off after that. Have raised pops and snow amounts for portions of North Central Montana. Emanuel && .AVIATION... Updated 0040Z. A moist northwest flow aloft will continue over Montana through Thursday. Scattered showers can be expected around terrain across Central Montana. Activity diminishes overnight but small areas of light snow may persist across some valley locations in the forecast area. Expect local MVFR conditions and mountain obscurations through 12Z in these locations. Precipitation expected to mostly end with cloud cover decreasing from the north after 12Z. && .PREV DISCUSSION...Issued 248 PM MST Wed Feb 13 2013 Wednesday through Friday...Convective activity continues to develop and move across Central and North Central Montana with showers slowly moving southward into the Mountains of Southwest Montana. Convective activity should continue into the evening hours but diminish significantly by sunset when daytime heating no longer drives the thermal activity. Temperatures decrease back towards seasonal averages tonight behind the cold front. High temperatures will be limited as the cool air mass slowly moderates over the next 24 hours. Some moisture aloft will allow for the possibility of snow showers over the higher terrain through Thursday night...however no significant accumulations are expected...especially at the lower elevation. An upper level ridge will begin to move into the region by Friday and allow for drier and warmer conditions to again develop throughout the day...with temperatures rising back above seasonal averages. Suk Friday night through Wednesday night...Good consistency continues among the models for this period. An upper level ridge of high pressure building into Montana Friday night and Saturday will keep the area mostly dry and quite mild (10 to 15 degrees above normal - with highs on Saturday reaching into the 40s to lower 50s). A shortwave trough will flatten the ridge as it moves into the area from the Pacific Northwest coast on Saturday, bringing a chance of showers to the Rocky Mountain Front and increasing westerly downslope winds to the remainder of the area. This shortwave will then move southeast through the area Saturday night into Sunday with an associated Canadian cold front. The chance for precipitation will increase Saturday night, while models continue to bring widespread light snow to the area on Sunday. Have therefore increased the chance for precipitation a bit more through these periods. Temperatures will be quite cool with the frontal passage on Sunday, as highs will only reach into the upper 20s to mid 30s most areas. Forecast snowfall amounts are fairly light at this time (with most lower elevations only forecast to receive an inch or 2 of snow). However, this situation will continue to be monitored for potential winter weather highlights, as the warm-up prior to the snow may warm pavement enough that initially melting snow may refreeze with the passage of the cold front, causing icy roadways. This may become a situation similar to that from this past weekend. An upper level ridge of high pressure will then follow this system into the state Sunday night through Monday night, allowing temperatures to warm back closer to normal with a decreasing chance of snow. A deep upper level trough of low pressure will then move across the western CONUS Tuesday night through Wednesday. The trough is forecast to split somewhat, with the southern portion taking the bulk of the energy south of the area. Despite this, a low level easterly flow may bring enough moisture into the southern half of the state to allow a good chance of snow to develop across central/southwest Montana. Coulston && .PRELIMINARY POINT TEMPS/POPS... GTF 21 35 21 42 / 100 10 10 10 CTB 16 34 21 41 / 30 10 10 10 HLN 25 35 22 40 / 40 30 20 10 BZN 20 31 16 36 / 60 40 30 10 WEY 10 24 6 29 / 60 30 40 10 DLN 20 32 17 37 / 30 30 20 10 HVR 10 27 9 31 / 20 10 10 10 LWT 16 28 14 34 / 100 30 10 10 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1142 AM CST THU FEB 14 2013 .UPDATE... UPDATED EARLIER TO TEMPS TO RAISE A COUPLE OF DEGREES FOR TODAY AS TEMPS ACROSS THE NORTH STAYED WARM OVERNIGHT AND WERE ALREADY NEAR HIGHS. DISTURBANCE WILL CONTINUE TO PUSH SOUTH FROM S DAKOTA INTO NEBRASKA THIS AFTERNOON...WHILE ANOTHER DISTURBANCE IS EXITING SW NEBRASKA INTO CO/KS. WITH TEMPS GENERALLY IN THE MID 30S AND COLD AIR WITH THE DISTURBANCES AND SOME WEAK LIFT...EXPECTING MAINLY LIGHT SNOW SHOWERS OR FLURRIES. WIND ADVISORY CONTINUES FOR THE DAY...WITH WINDS STARTING TO INCREASE...WITH SEVERAL SITES APPROACHING ADV CRITERIA. LIKELY A MARGINAL EVENT...BUT STILL BE WILL A WINDY AFTERNOON. && .AVIATION... MVFR CIGS ASSOCIATED WITH A DISTURBANCE ACROSS S DAKOTA WILL SPREAD INTO NRN NEB...AND THE KVTN TERMINAL...THIS AFTERNOON. ALSO COULD SEE SOME LIGHT SNOW OR FLURRIES...AND WILL MENTION WITH A TEMPO GROUP. SW NEB...AND THE KLBF TERMINAL MAY SEE SOME ISOLD FLURRIES...HOWEVER COVERAGE DOES NOT WARRANT MENTION IN THE TAF AT THIS TIME. WILL CONTINUE TO MONITOR RADAR AND MAY AMEND FOR A BRIEF PERIOD OF LIGHT SNOW...ALTHOUGH DURATION SHOULD BE SHORT. CIGS EXPECTED TO REMAIN IN THE VFR CATEGORY FOR KLBF. WINDS THIS AFTERNOON WILL INCREASE TO 20 TO 30 KTS WITH HIGHER GUSTS. WINDS DIMINISH THIS EVENING BECOMING LESS THAN 10KTS OVERNIGHT. TOMORROW SOME LINGER FLURRIES/MVFR CIGS ACROSS THE AREA...HOWEVER NOT EXPECTING THE STRONG WINDS. && .PREV DISCUSSION... /ISSUED 633 AM CST THU FEB 14 2013/ UPDATE... DISCUSSION... NO MAJOR CHANGES TO THIS UPDATE. 06Z NAM IS A BIT DRIER WITH QPF AMOUNTS. SHSN CONVERAGE IS ABOUT THE SAME. LESS THAN AN INCH OF SNOW IS EXPECTED. PREV DISCUSSION... /ISSUED 328 AM CST THU FEB 14 2013/ DISCUSSION... NEAR TERM...TODAY AND TONIGHT. SCATTERED SNOW SHOWERS DEVELOP TODAY THROUGH THIS EVENING WITH THE PASSAGE OF AN ARCTIC FRONT. WINDS AHEAD AND BEHIND THE FRONT SHOULD REACH WIND ADVISORY CRITERIA. STEEP LAPSE RATES TO 600-700MB SUPPORT THE WIND AND CONVECTIVE PCPN. THE RUC AND OTHER MODELS SUPPORT STRATUS WHICH COULD PERSIST INTO TONIGHT ACROSS THE NORTH. TEMPERATURES THIS AFTN WILL BE CONTINGENT ON THE FRONTAL PASSAGE. THE HRRR AND RAP MODELS SHOWS 40S SOUTH AND 30S NORTH. A BLEND OF GEM AND NAM WAS THE BASIS FOR THE FCST WHICH GIVES A SIMILAR EFFECT. NEITHER THE RAP OR HRRR FCST MAX TEMPS...JUST HOURLY. WINDS AND TEMPS DROP TONIGHT AS THE ARCTIC HIGH BUILDS THROUGH THE UPPER MISSOURI BASIN AND PACIFIC HIGH PRESSURE BUILDS THROUGH THE HIGH PLAINS. ALL MODELS SHOW LOW PRESSURE DEVELOPING ACROSS ERN SD SIGNALING A REINFORCING COLD FRONT FOR FRIDAY. SHORT TERM...12Z FRIDAY THROUGH 12Z SUNDAY. BROAD CYCLONIC FLOW ACROSS THE NORTHERN AND CENTRAL PLAINS WILL REMAIN ON FRIDAY...WITH AN ADDITIONAL SHORTWAVE IMPULSE DIVING SOUTH THROUGH AMPLIFIED NORTHWESTERLY FLOW. DUE TO FAVORABLE UPPER JET DYNAMICS AND THE FACT THAT LOW LEVEL LAPSE RATES REMAIN STEEP WITHIN A SATURATED DENDRITIC LAYER...WILL MAINTAIN -SN AND FLURRIES ACROSS THE ENTIRE CWA ON FRIDAY. THE IMPULSE QUICKLY DROPS TO THE SOUTH WITH A WARM FRONT PUSHING WEST TO EAST FRIDAY NIGHT INTO SATURDAY...TEMPERATURES SHOULD START TO MODERATE...WITH HIGHS APPROACHING 50 SOUTH OF INTERSTATE 80 AND ACROSS THE EASTERN PANHANDLE. LONG TERM...12Z SUNDAY AND BEYOND. SHORTWAVE RIDGING ACROSS THE REGION WILL GIVE WAY TO PROGRESSIVE ZONAL FLOW AS A TROUGH ADVANCES ACROSS THE NORTHERN ROCKIES ONTO THE PLAINS. IN ADVANCE OF THE TROUGH...SURFACE LOW PRESSURE OVER THE HIGH PLAINS WILL DEEPEN THROUGHOUT THE DAY ON SUNDAY...ALLOWING FOR WESTERLY TO SOUTHWESTERLY WIND WHICH WILL HELP WARM TEMPERATURES. LOOKING AT MID TO UPPER 50S GENERALLY OVER THE SOUTHERN HALF OF THE CWA...AND WHERE SNOW REMAINS...MID 40S SEEM PLAUSIBLE. THE WAVE WILL EVENTUALLY DRAG A COLD FRONT THROUGH THE CWA EARLY ON MONDAY...AT THIS TIME NOT SEEING MUCH SUPPORT FOR PRECIPITATION PRODUCTION...BUT HIGHS WILL BE SOME 15-20 DEGREES COOLER. THE NEXT IN LINE OF SHORTWAVE RIDGING ARRIVES EARLY TO MIDDLE NEXT WEEK...HOWEVER WE WILL BE RECYCLING SOME COLDER AIR BACK FROM THE EAST...SO A WARM UP MAY BE MODERATED SOMEWHAT. ATTENTION THEN TURNS TO THE NEXT SIGNIFICANT TROUGH WHICH SHOULD BE LOCATED ACROSS THE GREAT BASIN AROUND 12Z ON WEDNESDAY. SURPRISINGLY...THERE IS BETTER THAN AVERAGE CONTINUITY/AGREEMENT BETWEEN THE LONGER RANGE SOLUTIONS AND SEVERAL ENSEMBLE MEMBERS...WHICH SUGGEST A POTENTIALLY SIGNIFICANT STORM FOR THE CWA...SIMILAR TO THE TRACK OF LAST WEEKEND/S SYSTEM. ONE DIFFERENCE IS THAT THE MODELS ARE SHOWING SOME NEGATIVELY TILTED TENDENCIES WITH THE OVERALL SYSTEM...ALLOWING FOR A MUCH LONGER PERIOD OF QPF ACROSS THE CWA...INTERESTING. THAT BEING SAID...THE POTENTIAL SYSTEM IS SEVEN DAY/S OUT...SO WON`T GET TOO EXCITED YET. THUS WILL LIMIT POPS AT 30 PERCENT /OR LESS/ FOR NOW. && .LBF WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 6 PM CST /5 PM MST/ THIS EVENING FOR NEZ004>010-022>029-035>038-056>059-069>071-094. && $$ UPDATE/AVIATION....MASEK
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1116 AM CST THU FEB 14 2013 .AVIATION...18Z TAF. WINDS WILL INCREASE A LITTLE YET THIS AFTERNOON AND THEN DIMINISH AS THE SUN GOES DOWN THIS EVENING. THERE ARE SOME MID AND LOWER CLOUDS TO THE NORTHWEST THAT WILL BE MOVING INTO THE KGRI TERMINAL AREA THIS AFTERNOON...BUT THE CEILINGS WILL REMAIN VFR THROUGH THE PERIOD. && .PREV DISCUSSION... /ISSUED 529 AM CST THU FEB 14 2013/ SHORT TERM...ALTHOUGH NO TRULY HIGH-IMPACT WEATHER IS EXPECTED DURING THE NEXT 72 HOURS...THINGS START OFF WITH A SOMEWHAT MARGINAL WIND ADVISORY EVENT TODAY...FOLLOWED BY PESKY HARD-TO-PIN-DOWN FLURRY/BRIEF SNOW SHOWER CHANCES FROM THIS AFTERNOON THROUGH FRIDAY EVENING. ALTHOUGH THE VAST MAJORITY OF THE CWA IS UNLIKELY TO SEE ACCUMULATING SNOW...A LIGHT DUSTING HERE OR THERE IS NOT OUT OF THE QUESTION ESPECIALLY FRIDAY AFTERNOON/EVENING. 10Z OBJECTIVE CENTRAL PLAINS SURFACE ANALYSIS REVEALS A SUBTLE SURFACE TROUGH FROM EASTERN-SOUTHERN KANSAS...TRAILING SOUTHWEST FROM A 1001MB LOW IN WISCONSIN. A BROAD WEST-NORTHWEST SURFACE WIND REGIME WAS FIRMLY IN PLACE ACROSS THE CWA...WITH SUSTAINED SPEEDS GENERALLY 5-15 MPH. THESE STEADY BREEZES ARE RESULTING IN AT LEAST A SLIGHTLY-WARMER-THAN-EXPECTED NIGHT...WITH OVERNIGHT LOWS IN MOST AREAS LIKELY BOTTOMING OUT BETWEEN 27-31 DEGREES. TO THE NORTH...A SOMEWHAT ILL-DEFINED EAST-WEST COLD FRONT IS ALIGNED ACROSS SOUTH DAKOTA...WITH THIS BOUNDARY EXPECTED TO VERY SLOWLY BLEED SOUTHWARD ACROSS THE LOCAL AREA AS THE DAY WEARS ON. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA IS HIGHLIGHTED BY INCREASINGLY ACTIVE NORTHWEST FLOW...AS JUST IN THE PAST 12 HOURS A PAIR OF LOW AMPLITUDE CLIPPER SHORTWAVE TROUGHS HAVE TRACKED ALONG A CORRIDOR FROM THE DAKOTAS TOWARD IA. 11-3.9 MICRON SATELLITE IMAGERY SHOWS RELATIVELY CLEAR SKIES STEADILY GIVING WAY TO INCREASING HIGH CLOUD COVER FROM THE WEST. MEANWHILE...A SMALL BATCH OF MID LEVEL CLOUDS THAT BROUGHT SOME RATHER UNEXPECTED BRIEF SPRINKLES TO PARTS OF THE CWA LAST EVENING HAS MOVED WELL OFF TO THE SOUTHEAST. TODAY...THE MAIN FOCUS CONTINUES TO BE ON INCREASING NORTHWEST WINDS...ALTHOUGH WILL STATE UP FRONT THAT THE INTENSITY/DURATION OF THE STRONGEST WINDS HAS NOW TRENDED DOWNWARD A BIT OVER THE PAST FEW MODEL RUNS...SO THIS WILL LIKELY BE A SOMEWHAT MARGINAL WIND ADVISORY EVENT. WINDS WILL NOT START THE DAY ALL THAT STRONG...AS IT WILL BE AT LEAST LATE MORNING/EARLY AFTERNOON BEFORE INCREASING PRESSURE RISES AND DEEPENING MIXING BEHIND THE INITIAL PASSING COLD FRONT RAMPS SPEEDS UP. ALOFT...THIS INCREASING SURGE OF NORTHWEST WINDS WILL BE DRIVEN BY LOW AMPLITUDE SHORTWAVE TROUGH DROPPING SOUTH OF SD INTO NEB/IA. HAVE MADE NO CHANGES WHATSOEVER TO THE WIND ADVISORY ITSELF...STARTING AT 11 AM AND ENDING AT 6 PM...WITH THE OVERALL BEST TIME FRAME FOR SUSTAINED SPEEDS NEARING/MEETING 30 MPH WITH GUSTS 40 TO POSSIBLY 45 MPH CENTERED DURING THE MID-AFTERNOON. FARTHER SOUTH IN OUR KS ZONES...AM GENERALLY EXPECTING SUSTAINED SPEEDS TO TOP OUT CLOSE TO 25 MPH...THUS FALLING ABOUT 5 MPH SHORT OF ADVISORY CRITERIA SO NOT ANTICIPATING ANY SOUTHWARD EXPANSION AT THIS TIME. HOURLY TEMP TRENDS WILL BE TRICKY TODAY WITH A FAIRLY RAPID INITIAL RISE THEN FOLLOWED BY A SLOW-BUT-STEADY FALL AS THE AFTERNOON WEARS ON AND COLD AIR ADVECTION TAKES HOLD. HAVE FOLLOWED THE 06Z RAP SOLUTION FAIRLY CLOSELY...WHICH ACTUALLY RESULTED IN ABOUT A 4 DEGREE UPWARD BUMP TO HIGHS WITH MOST OF SOUTH CENTRAL NEBRASKA NOW EXPECTED TO AT LEAST BRIEFLY TOUCH THE MID IF NOT UPPER 40S EXCEPT COOLER FAR NORTH...AND KS ZONES RIGHT AROUND 50. THE ONLY CAVEAT HERE IS WHETHER INCOMING MID/HIGH CLOUDS ARE THICK ENOUGH TO TEMPER THINGS A BIT. PRECIPITATION WISE...KEPT ALL MENTION OUT OF THE MORNING HOURS...BEFORE BRINGING IN NON-MEASURABLE CHANCES FOR FLURRIES AND/OR SPRINKLES DURING THE AFTERNOON IN RESPONSE TO THE INCOMING MID LEVEL SHORTWAVE TROUGH AND INCREASING UPPER JET DYNAMICS. RAW MODEL QPF FIELDS CONTINUE TO BE ALL OVER THE PLACE...AND ALTHOUGH THE MAJORITY OF THE CWA MAY NOT SEE A SINGLE RAIN DROP OR SNOWFLAKE BEFORE SUNSET...IT SEEMS THE MOST FAVORED AREAS WOULD BE NORTH OF NEBRASKA HWY 92 AND ALSO WITHIN THE SOUTHWEST 1/4 OF THE CWA. THIS EVENING/TONIGHT...ALTHOUGH IT WILL REMAIN QUITE BREEZY EARLY ON THIS EVENING...HAVE FAIRLY HIGH CONFIDENCE THAT THE WIND SPEEDS WILL SAFELY FALL BELOW ADVISORY CRITERIA BY THE CURRENT EXPIRATION TIME OF 6 PM...WITH SUSTAINED SPEEDS THEN STEADILY TRENDING DOWN THROUGH THE REMAINDER OF THE NIGHT AS SURFACE HIGH PRESSURE SETTLES IN FROM THE NORTHWEST. IN FACT AFTER MIDNIGHT...ONLY LOOKING AT SPEEDS AROUND 10 MPH MOST AREAS. ALTHOUGH THE VAST MAJORITY OF THE CWA WILL LIKELY REMAIN PRECIP-FREE TONIGHT...ITS OFTEN SEEN IN THIS TYPE OF NORTHWEST FLOW PATTERN THAT EVEN SMALL BANDS/PATCHES OF MID LEVEL CLOUDS COULD PRODUCE SOME SPORADIC FLURRIES...SO WILL CONTINUE TO KEEP IT SIMPLE AND BLANKET THE ENTIRE CWA WITH THIS SLIGHT FLURRY CHANCE. NUDGED DOWN LOW TEMPS GENERALLY 1-2 DEGREES FROM PREVIOUS GRIDS...WITH MOST AREAS BOTTOMING OUT 15-19 DEGREES ASSUMING THAT A CLOUD BAND DOESN/T PARK ITSELF SOMEWHERE AND HOLD THINGS UP A BIT HIGHER. FRIDAY INTO FRIDAY EVENING WILL HOLD THE BEST POTENTIAL FOR A MORE WIDESPREAD COVERAGE OF FLURRIES AND POSSIBLY VERY LIGHT SNOW ACCUMULATIONS IN A FEW AREAS...AS THE FINAL AND LIKELY MOST VIGOROUS NORTHWEST-FLOW SHORTWAVE TROUGH DROPS SOUTHWARD ACROSS THE HEART OF THE LOCAL AREA...FOCUSED WITHIN THE EXIT REGION OF A RATHER STOUT MERIDIONAL UPPER JET OF 120+ KNOTS. ALTHOUGH WILL KEEP AN OUTSIDE CHANCE OF A FLURRY GOING ON FRIDAY MORNING...HAVE ADDED A SLIGHT CHANCE MEASURABLE POP TO THE AFTERNOON/EVENING HOURS AS THE MAIN SHORTWAVE AXIS PASSES OVER. THIS IS LOOKING LIKE A FAIRLY CLASSIC SETUP FOR QUICK NORTH-TO-SOUTH MOVING BRIEF SNOW SHOWERS...GIVEN STEEP LOW LEVEL LAPSE RATES AND DEEP MIXING. THIS SCENARIO IS WELL CAPTURED IN THE REFLECTIVITY PROG OF THE 00Z 4KM WRF-NMM...WITH HIT AND MISS SNOW SHOWERS BLOSSOMING ACROSS THE AREA DURING THE DAY BEFORE WEAKENING AND EVENTUALLY MOVING OUT ALTOGETHER BY MIDNIGHT AS THE BACK EDGE OF THE MID LEVEL TROUGH AXIS PASSES. THIS WILL BE A SITUATION WHERE SOME AREAS SEE A LIGHT DUSTING OF SNOW...WHILE OTHERS MISS OUT COMPLETELY...AND AS THESE MESOSCALE DETAILS BECOME CLEARER ITS POSSIBLE THAT POPS MIGHT BE RAISED ABOVE THE CURRENT 20 PERCENT IN SOME AREAS. ALTHOUGH AFTERNOON/EVENING WIND SPEEDS WILL NOT BE AS STRONG AS TODAY...AT LEAST A FEW HOURS OF SUSTAINED 15-20 MPH SPEEDS IS EXPECTED...WHICH COULD POSSIBLY RESULT IN LOCALIZED/BRIEF VISIBILITY RESTRICTIONS UNDER PASSING SNOW SHOWERS...BUT NOT A WIDESPREAD HAZARD WORTHY OF MENTION IN THE HWO AT THIS TIME. TEMP-WISE...MADE A VERY SMALL UPWARD NUDGE TO PREVIOUS HIGHS BUT THIS WILL STILL BE THE COLDEST DAY OF THE WEEK WITH HIGHS IN THE 30S MOST AREAS AND MAYBE ONLY UPPER 20S FAR NORTH. LIGHT WESTERLY BREEZES LATE FRIDAY NIGHT SHOULD KEEP LOWS FROM TANKING TOO FAR...BUT STILL DROPPING DOWN BETWEEN 14-18 MOST AREAS. SATURDAY INTO SATURDAY NIGHT...HAVE RATHER HIGH CONFIDENCE IN A DRY PERIOD WITH WARMING TEMPERATURES...AS THE BIG PICTURE ALOFT INVOLVES AN INVADING SHORTWAVE RIDGE IN THE WAKE OF A DEEP LONGWAVE TROUGH EXITING EASTWARD ACROSS THE EASTERN CONUS. IN THE LOW LEVELS...WEST-SOUTHWEST BREEZES GENERALLY 10-15 MPH WILL BRING IN SOME PRETTY STOUT WARM AIR ADVECTION DURING THE DAY...ALTHOUGH THIS MAY BE TEMPERED SOMEWHAT BY WHAT COULD BE A FAIRLY SOLID PASSING DECK OF MID CLOUDS. NO MATTER WHAT THOUGH...A NOTABLE WARM-UP OVER FRIDAY IS IN STORE...AND BASED ON A BLEND OF THE 00Z NAM/ECMWF RAISED 3-4 DEGREES FROM PREVIOUS FORECAST ESPECIALLY ACROSS WESTERN COUNTIES...NOW CALLING FOR A RANGE FROM LOW 40S EAST TO NEAR 50 WEST. SUPPOSE A FEW SPRINKLES FALLING OUT OF THE AFOREMENTIONED MID DECK IS NOT OUT OF THE QUESTION...BUT SEEMS UNLIKELY ENOUGH FOR NOW TO OMIT ANY GRID MENTION. SATURDAY NIGHT...LIGHT WESTERLY BREEZES SHOULD KEEP LOW TEMPS SEVERAL DEGREES WARMER THAN THE PREVIOUS FEW NIGHTS...AND MADE LITTLE CHANGE WITH MID 20S MOST AREAS. LONG TERM...SUNDAY THROUGH WEDNESDAY. THE LONG TERM WILL CONSIST OF A SERIES OF PROGRESSIVE SHORTWAVE TROUGHS AND RIDGES OF PACIFIC ORIGIN. TOOK MORE OF A CONSENSUS APPROACH FOR THE LONG TERM...FAVORING ENSEMBLE MEANS. SUNDAY APPEARS THAT IT WILL BE THE MOST MILD DAY AS 850 MB TEMPERATURES WARM UP NICELY IN ASSOCIATION WITH A PASSING SHORTWAVE RIDGE. THERE WILL BE INCREASED WARMING JUST AHEAD OF AN APPROACHING COLD FRONT...WITH SURFACE SOUTHWEST WIND DECREASING AS THE FRONT APPROACHES...CONDITIONS COULD BECOME DOWNRIGHT SPRING-LIKE FOR THE AFTERNOON. COLDER AIR SPILLS IN FOR MONDAY...AND INCREASED WIND SPEEDS FROM THE NORTH QUITE A BIT FROM ALLBLEND/CONSALL AS A RESULT OF THE HEALTHY COLD AIR ADVECTION. THE COOL SURFACE HIGH FINALLY MAKES ITS WAY INTO OUR AREA BY TUESDAY...WHICH SHOULD BE JUST ABOUT THE COOLEST HIGH FOR THE LONG TERM BEFORE A BIT OF A REBOUND OCCURS FOR WEDNESDAY. THIS REBOUND OCCURS AHEAD OF A DIGGING MEAN LONG TROUGH OVER THE ROCKY MOUNTAINS WHICH WILL BE MOVING EAST. && .GID WATCHES/WARNINGS/ADVISORIES... NE...WIND ADVISORY UNTIL 6 PM CST THIS EVENING FOR NEZ039>041-046>049- 060>064-072>077-082>087. KS...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
633 AM CST THU FEB 14 2013 .UPDATE... .DISCUSSION... NO MAJOR CHANGES TO THIS UPDATE. 06Z NAM IS A BIT DRIER WITH QPF AMOUNTS. SHSN CONVERAGE IS ABOUT THE SAME. LESS THAN AN INCH OF SNOW IS EXPECTED. && .PREV DISCUSSION... /ISSUED 529 AM CST THU FEB 14 2013/ UPDATE... AVIATION... SCATTERED MVFR WILL SPREAD INTO NRN NEB THIS AFTN WITH THE PASSAGE OF AN ARCTIC FRONT CURRENTLY AT 11Z NEAR KSDY. SCATTERED SNOW SHOWERS AND MVFR WILL ACCOMPANY THE FRONT. MVFR AND ISOLATED SNOW SHOWERS MAY PERSIST TONIGHT ACROSS THE NORTH. ELSEWHERE MOSTLY VFR IS EXPECTED WITH ISOLATED RAIN OR SNOW SHOWERS DURING THE DAY TODAY. WINDS WILL INCREASE THIS AFTERNOON TO 32025G40KT AND DECREASE AT SUNSET. PREV DISCUSSION... /ISSUED 328 AM CST THU FEB 14 2013/ DISCUSSION... NEAR TERM...TODAY AND TONIGHT. SCATTERED SNOW SHOWERS DEVELOP TODAY THROUGH THIS EVENING WITH THE PASSAGE OF AN ARCTIC FRONT. WINDS AHEAD AND BEHIND THE FRONT SHOULD REACH WIND ADVISORY CRITERIA. STEEP LAPSE RATES TO 600-700MB SUPPORT THE WIND AND CONVECTIVE PCPN. THE RUC AND OTHER MODELS SUPPORT STRATUS WHICH COULD PERSIST INTO TONIGHT ACROSS THE NORTH. TEMPERATURES THIS AFTN WILL BE CONTINGENT ON THE FRONTAL PASSAGE. THE HRRR AND RAP MODELS SHOWS 40S SOUTH AND 30S NORTH. A BLEND OF GEM AND NAM WAS THE BASIS FOR THE FCST WHICH GIVES A SIMILAR EFFECT. NEITHER THE RAP OR HRRR FCST MAX TEMPS...JUST HOURLY. WINDS AND TEMPS DROP TONIGHT AS THE ARCTIC HIGH BUILDS THROUGH THE UPPER MISSOURI BASIN AND PACIFIC HIGH PRESSURE BUILDS THROUGH THE HIGH PLAINS. ALL MODELS SHOW LOW PRESSURE DEVELOPING ACROSS ERN SD SIGNALING A REINFORCING COLD FRONT FOR FRIDAY. SHORT TERM...12Z FRIDAY THROUGH 12Z SUNDAY. BROAD CYCLONIC FLOW ACROSS THE NORTHERN AND CENTRAL PLAINS WILL REMAIN ON FRIDAY...WITH AN ADDITIONAL SHORTWAVE IMPULSE DIVING SOUTH THROUGH AMPLIFIED NORTHWESTERLY FLOW. DUE TO FAVORABLE UPPER JET DYNAMICS AND THE FACT THAT LOW LEVEL LAPSE RATES REMAIN STEEP WITHIN A SATURATED DENDRITIC LAYER...WILL MAINTAIN -SN AND FLURRIES ACROSS THE ENTIRE CWA ON FRIDAY. THE IMPULSE QUICKLY DROPS TO THE SOUTH WITH A WARM FRONT PUSHING WEST TO EAST FRIDAY NIGHT INTO SATURDAY...TEMPERATURES SHOULD START TO MODERATE...WITH HIGHS APPROACHING 50 SOUTH OF INTERSTATE 80 AND ACROSS THE EASTERN PANHANDLE. LONG TERM...12Z SUNDAY AND BEYOND. SHORTWAVE RIDGING ACROSS THE REGION WILL GIVE WAY TO PROGRESSIVE ZONAL FLOW AS A TROUGH ADVANCES ACROSS THE NORTHERN ROCKIES ONTO THE PLAINS. IN ADVANCE OF THE TROUGH...SURFACE LOW PRESSURE OVER THE HIGH PLAINS WILL DEEPEN THROUGHOUT THE DAY ON SUNDAY...ALLOWING FOR WESTERLY TO SOUTHWESTERLY WIND WHICH WILL HELP WARM TEMPERATURES. LOOKING AT MID TO UPPER 50S GENERALLY OVER THE SOUTHERN HALF OF THE CWA...AND WHERE SNOW REMAINS...MID 40S SEEM PLAUSIBLE. THE WAVE WILL EVENTUALLY DRAG A COLD FRONT THROUGH THE CWA EARLY ON MONDAY...AT THIS TIME NOT SEEING MUCH SUPPORT FOR PRECIPITATION PRODUCTION...BUT HIGHS WILL BE SOME 15-20 DEGREES COOLER. THE NEXT IN LINE OF SHORTWAVE RIDGING ARRIVES EARLY TO MIDDLE NEXT WEEK...HOWEVER WE WILL BE RECYCLING SOME COLDER AIR BACK FROM THE EAST...SO A WARM UP MAY BE MODERATED SOMEWHAT. ATTENTION THEN TURNS TO THE NEXT SIGNIFICANT TROUGH WHICH SHOULD BE LOCATED ACROSS THE GREAT BASIN AROUND 12Z ON WEDNESDAY. SURPRISINGLY...THERE IS BETTER THAN AVERAGE CONTINUITY/AGREEMENT BETWEEN THE LONGER RANGE SOLUTIONS AND SEVERAL ENSEMBLE MEMBERS...WHICH SUGGEST A POTENTIALLY SIGNIFICANT STORM FOR THE CWA...SIMILAR TO THE TRACK OF LAST WEEKEND/S SYSTEM. ONE DIFFERENCE IS THAT THE MODELS ARE SHOWING SOME NEGATIVELY TILTED TENDENCIES WITH THE OVERALL SYSTEM...ALLOWING FOR A MUCH LONGER PERIOD OF QPF ACROSS THE CWA...INTERESTING. THAT BEING SAID...THE POTENTIAL SYSTEM IS SEVEN DAY/S OUT...SO WON`T GET TOO EXCITED YET. THUS WILL LIMIT POPS AT 30 PERCENT /OR LESS/ FOR NOW. AVIATION... MVFR WILL SPREAD INTO NRN NEB THIS AFTN WITH THE PASSAGE OF AN ARCTIC FRONT CURRENTLY AT 08Z NEAR KGGW. SCATTERED SNOW SHOWERS WILL ACCOMPANY THE FRONT. MVFR AND ISOLATES SNOW SHOWERS MAY PERSIST TONIGHT ACROSS THE NORTH. ELSEWHERE MOSTLY VFR IS EXPECTED WITH ISOLATED RAIN OR SNOW SHOWERS DURING THE DAY TODAY. && .LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY FROM 10 AM CST /9 AM MST/ THIS MORNING TO 6 PM CST /5 PM MST/ THIS EVENING FOR NEZ004>010-022>029-035>038-056>059- 069>071-094. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION....CDC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
540 AM CST THU FEB 14 2013 .AVIATION...12Z KGRI TAF. WIND WILL INCREASE SPEED FOR THIS MORNING WITH INCREASING HEIGHT RISES BEHIND A COLD FRONT. CEILINGS COULD BE A BIT TRICKY...YET PROBABLY MAINLY IN THE MID-RANGE FOR HEIGHT. COULD BE SOME SPRINKLE/FLURRY ACTIVITY...BUT AIR IN LOWER LEVELS IS QUITE DRY...SO THIS WILL NOT AMOUNT TO A WHOLE LOT...PERHAPS GIVING A QUICK BIT OF A BURST OF WIND. MODELS INDICATE THAT THERE COULD BE AT LEAST SOME SCATTERED STRATUS STICKING AROUND FOR THIS EVENING WITH DECREASING WIND BUT CONTINUING POSSIBILITY OF FLURRIES...NOT INCLUDED IN THE FORECAST AS CONFIDENCE IS NOT HIGH FOR THIS OCCURRENCE. && .PREV DISCUSSION... /ISSUED 529 AM CST THU FEB 14 2013/ SHORT TERM...ALTHOUGH NO TRULY HIGH-IMPACT WEATHER IS EXPECTED DURING THE NEXT 72 HOURS...THINGS START OFF WITH A SOMEWHAT MARGINAL WIND ADVISORY EVENT TODAY...FOLLOWED BY PESKY HARD-TO-PIN-DOWN FLURRY/BRIEF SNOW SHOWER CHANCES FROM THIS AFTERNOON THROUGH FRIDAY EVENING. ALTHOUGH THE VAST MAJORITY OF THE CWA IS UNLIKELY TO SEE ACCUMULATING SNOW...A LIGHT DUSTING HERE OR THERE IS NOT OUT OF THE QUESTION ESPECIALLY FRIDAY AFTERNOON/EVENING. 10Z OBJECTIVE CENTRAL PLAINS SURFACE ANALYSIS REVEALS A SUBTLE SURFACE TROUGH FROM EASTERN-SOUTHERN KANSAS...TRAILING SOUTHWEST FROM A 1001MB LOW IN WISCONSIN. A BROAD WEST-NORTHWEST SURFACE WIND REGIME WAS FIRMLY IN PLACE ACROSS THE CWA...WITH SUSTAINED SPEEDS GENERALLY 5-15 MPH. THESE STEADY BREEZES ARE RESULTING IN AT LEAST A SLIGHTLY-WARMER-THAN-EXPECTED NIGHT...WITH OVERNIGHT LOWS IN MOST AREAS LIKELY BOTTOMING OUT BETWEEN 27-31 DEGREES. TO THE NORTH...A SOMEWHAT ILL-DEFINED EAST-WEST COLD FRONT IS ALIGNED ACROSS SOUTH DAKOTA...WITH THIS BOUNDARY EXPECTED TO VERY SLOWLY BLEED SOUTHWARD ACROSS THE LOCAL AREA AS THE DAY WEARS ON. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA IS HIGHLIGHTED BY INCREASINGLY ACTIVE NORTHWEST FLOW...AS JUST IN THE PAST 12 HOURS A PAIR OF LOW AMPLITUDE CLIPPER SHORTWAVE TROUGHS HAVE TRACKED ALONG A CORRIDOR FROM THE DAKOTAS TOWARD IA. 11-3.9 MICRON SATELLITE IMAGERY SHOWS RELATIVELY CLEAR SKIES STEADILY GIVING WAY TO INCREASING HIGH CLOUD COVER FROM THE WEST. MEANWHILE...A SMALL BATCH OF MID LEVEL CLOUDS THAT BROUGHT SOME RATHER UNEXPECTED BRIEF SPRINKLES TO PARTS OF THE CWA LAST EVENING HAS MOVED WELL OFF TO THE SOUTHEAST. TODAY...THE MAIN FOCUS CONTINUES TO BE ON INCREASING NORTHWEST WINDS...ALTHOUGH WILL STATE UP FRONT THAT THE INTENSITY/DURATION OF THE STRONGEST WINDS HAS NOW TRENDED DOWNWARD A BIT OVER THE PAST FEW MODEL RUNS...SO THIS WILL LIKELY BE A SOMEWHAT MARGINAL WIND ADVISORY EVENT. WINDS WILL NOT START THE DAY ALL THAT STRONG...AS IT WILL BE AT LEAST LATE MORNING/EARLY AFTERNOON BEFORE INCREASING PRESSURE RISES AND DEEPENING MIXING BEHIND THE INITIAL PASSING COLD FRONT RAMPS SPEEDS UP. ALOFT...THIS INCREASING SURGE OF NORTHWEST WINDS WILL BE DRIVEN BY LOW AMPLITUDE SHORTWAVE TROUGH DROPPING SOUTH OF SD INTO NEB/IA. HAVE MADE NO CHANGES WHATSOEVER TO THE WIND ADVISORY ITSELF...STARTING AT 11 AM AND ENDING AT 6 PM...WITH THE OVERALL BEST TIME FRAME FOR SUSTAINED SPEEDS NEARING/MEETING 30 MPH WITH GUSTS 40 TO POSSIBLY 45 MPH CENTERED DURING THE MID-AFTERNOON. FARTHER SOUTH IN OUR KS ZONES...AM GENERALLY EXPECTING SUSTAINED SPEEDS TO TOP OUT CLOSE TO 25 MPH...THUS FALLING ABOUT 5 MPH SHORT OF ADVISORY CRITERIA SO NOT ANTICIPATING ANY SOUTHWARD EXPANSION AT THIS TIME. HOURLY TEMP TRENDS WILL BE TRICKY TODAY WITH A FAIRLY RAPID INITIAL RISE THEN FOLLOWED BY A SLOW-BUT-STEADY FALL AS THE AFTERNOON WEARS ON AND COLD AIR ADVECTION TAKES HOLD. HAVE FOLLOWED THE 06Z RAP SOLUTION FAIRLY CLOSELY...WHICH ACTUALLY RESULTED IN ABOUT A 4 DEGREE UPWARD BUMP TO HIGHS WITH MOST OF SOUTH CENTRAL NEBRASKA NOW EXPECTED TO AT LEAST BRIEFLY TOUCH THE MID IF NOT UPPER 40S EXCEPT COOLER FAR NORTH...AND KS ZONES RIGHT AROUND 50. THE ONLY CAVEAT HERE IS WHETHER INCOMING MID/HIGH CLOUDS ARE THICK ENOUGH TO TEMPER THINGS A BIT. PRECIPITATION WISE...KEPT ALL MENTION OUT OF THE MORNING HOURS...BEFORE BRINGING IN NON-MEASURABLE CHANCES FOR FLURRIES AND/OR SPRINKLES DURING THE AFTERNOON IN RESPONSE TO THE INCOMING MID LEVEL SHORTWAVE TROUGH AND INCREASING UPPER JET DYNAMICS. RAW MODEL QPF FIELDS CONTINUE TO BE ALL OVER THE PLACE...AND ALTHOUGH THE MAJORITY OF THE CWA MAY NOT SEE A SINGLE RAIN DROP OR SNOWFLAKE BEFORE SUNSET...IT SEEMS THE MOST FAVORED AREAS WOULD BE NORTH OF NEBRASKA HWY 92 AND ALSO WITHIN THE SOUTHWEST 1/4 OF THE CWA. THIS EVENING/TONIGHT...ALTHOUGH IT WILL REMAIN QUITE BREEZY EARLY ON THIS EVENING...HAVE FAIRLY HIGH CONFIDENCE THAT THE WIND SPEEDS WILL SAFELY FALL BELOW ADVISORY CRITERIA BY THE CURRENT EXPIRATION TIME OF 6 PM...WITH SUSTAINED SPEEDS THEN STEADILY TRENDING DOWN THROUGH THE REMAINDER OF THE NIGHT AS SURFACE HIGH PRESSURE SETTLES IN FROM THE NORTHWEST. IN FACT AFTER MIDNIGHT...ONLY LOOKING AT SPEEDS AROUND 10 MPH MOST AREAS. ALTHOUGH THE VAST MAJORITY OF THE CWA WILL LIKELY REMAIN PRECIP-FREE TONIGHT...ITS OFTEN SEEN IN THIS TYPE OF NORTHWEST FLOW PATTERN THAT EVEN SMALL BANDS/PATCHES OF MID LEVEL CLOUDS COULD PRODUCE SOME SPORADIC FLURRIES...SO WILL CONTINUE TO KEEP IT SIMPLE AND BLANKET THE ENTIRE CWA WITH THIS SLIGHT FLURRY CHANCE. NUDGED DOWN LOW TEMPS GENERALLY 1-2 DEGREES FROM PREVIOUS GRIDS...WITH MOST AREAS BOTTOMING OUT 15-19 DEGREES ASSUMING THAT A CLOUD BAND DOESN/T PARK ITSELF SOMEWHERE AND HOLD THINGS UP A BIT HIGHER. FRIDAY INTO FRIDAY EVENING WILL HOLD THE BEST POTENTIAL FOR A MORE WIDESPREAD COVERAGE OF FLURRIES AND POSSIBLY VERY LIGHT SNOW ACCUMULATIONS IN A FEW AREAS...AS THE FINAL AND LIKELY MOST VIGOROUS NORTHWEST-FLOW SHORTWAVE TROUGH DROPS SOUTHWARD ACROSS THE HEART OF THE LOCAL AREA...FOCUSED WITHIN THE EXIT REGION OF A RATHER STOUT MERIDIONAL UPPER JET OF 120+ KNOTS. ALTHOUGH WILL KEEP AN OUTSIDE CHANCE OF A FLURRY GOING ON FRIDAY MORNING...HAVE ADDED A SLIGHT CHANCE MEASURABLE POP TO THE AFTERNOON/EVENING HOURS AS THE MAIN SHORTWAVE AXIS PASSES OVER. THIS IS LOOKING LIKE A FAIRLY CLASSIC SETUP FOR QUICK NORTH-TO-SOUTH MOVING BRIEF SNOW SHOWERS...GIVEN STEEP LOW LEVEL LAPSE RATES AND DEEP MIXING. THIS SCENARIO IS WELL CAPTURED IN THE REFLECTIVITY PROG OF THE 00Z 4KM WRF-NMM...WITH HIT AND MISS SNOW SHOWERS BLOSSOMING ACROSS THE AREA DURING THE DAY BEFORE WEAKENING AND EVENTUALLY MOVING OUT ALTOGETHER BY MIDNIGHT AS THE BACK EDGE OF THE MID LEVEL TROUGH AXIS PASSES. THIS WILL BE A SITUATION WHERE SOME AREAS SEE A LIGHT DUSTING OF SNOW...WHILE OTHERS MISS OUT COMPLETELY...AND AS THESE MESOSCALE DETAILS BECOME CLEARER ITS POSSIBLE THAT POPS MIGHT BE RAISED ABOVE THE CURRENT 20 PERCENT IN SOME AREAS. ALTHOUGH AFTERNOON/EVENING WIND SPEEDS WILL NOT BE AS STRONG AS TODAY...AT LEAST A FEW HOURS OF SUSTAINED 15-20 MPH SPEEDS IS EXPECTED...WHICH COULD POSSIBLY RESULT IN LOCALIZED/BRIEF VISIBILITY RESTRICTIONS UNDER PASSING SNOW SHOWERS...BUT NOT A WIDESPREAD HAZARD WORTHY OF MENTION IN THE HWO AT THIS TIME. TEMP-WISE...MADE A VERY SMALL UPWARD NUDGE TO PREVIOUS HIGHS BUT THIS WILL STILL BE THE COLDEST DAY OF THE WEEK WITH HIGHS IN THE 30S MOST AREAS AND MAYBE ONLY UPPER 20S FAR NORTH. LIGHT WESTERLY BREEZES LATE FRIDAY NIGHT SHOULD KEEP LOWS FROM TANKING TOO FAR...BUT STILL DROPPING DOWN BETWEEN 14-18 MOST AREAS. SATURDAY INTO SATURDAY NIGHT...HAVE RATHER HIGH CONFIDENCE IN A DRY PERIOD WITH WARMING TEMPERATURES...AS THE BIG PICTURE ALOFT INVOLVES AN INVADING SHORTWAVE RIDGE IN THE WAKE OF A DEEP LONGWAVE TROUGH EXITING EASTWARD ACROSS THE EASTERN CONUS. IN THE LOW LEVELS...WEST-SOUTHWEST BREEZES GENERALLY 10-15 MPH WILL BRING IN SOME PRETTY STOUT WARM AIR ADVECTION DURING THE DAY...ALTHOUGH THIS MAY BE TEMPERED SOMEWHAT BY WHAT COULD BE A FAIRLY SOLID PASSING DECK OF MID CLOUDS. NO MATTER WHAT THOUGH...A NOTABLE WARM-UP OVER FRIDAY IS IN STORE...AND BASED ON A BLEND OF THE 00Z NAM/ECMWF RAISED 3-4 DEGREES FROM PREVIOUS FORECAST ESPECIALLY ACROSS WESTERN COUNTIES...NOW CALLING FOR A RANGE FROM LOW 40S EAST TO NEAR 50 WEST. SUPPOSE A FEW SPRINKLES FALLING OUT OF THE AFOREMENTIONED MID DECK IS NOT OUT OF THE QUESTION...BUT SEEMS UNLIKELY ENOUGH FOR NOW TO OMIT ANY GRID MENTION. SATURDAY NIGHT...LIGHT WESTERLY BREEZES SHOULD KEEP LOW TEMPS SEVERAL DEGREES WARMER THAN THE PREVIOUS FEW NIGHTS...AND MADE LITTLE CHANGE WITH MID 20S MOST AREAS. LONG TERM...SUNDAY THROUGH WEDNESDAY. THE LONG TERM WILL CONSIST OF A SERIES OF PROGRESSIVE SHORTWAVE TROUGHS AND RIDGES OF PACIFIC ORIGIN. TOOK MORE OF A CONSENSUS APPROACH FOR THE LONG TERM...FAVORING ENSEMBLE MEANS. SUNDAY APPEARS THAT IT WILL BE THE MOST MILD DAY AS 850 MB TEMPERATURES WARM UP NICELY IN ASSOCIATION WITH A PASSING SHORTWAVE RIDGE. THERE WILL BE INCREASED WARMING JUST AHEAD OF AN APPROACHING COLD FRONT...WITH SURFACE SOUTHWEST WIND DECREASING AS THE FRONT APPROACHES...CONDITIONS COULD BECOME DOWNRIGHT SPRING-LIKE FOR THE AFTERNOON. COLDER AIR SPILLS IN FOR MONDAY...AND INCREASED WIND SPEEDS FROM THE NORTH QUITE A BIT FROM ALLBLEND/CONSALL AS A RESULT OF THE HEALTHY COLD AIR ADVECTION. THE COOL SURFACE HIGH FINALLY MAKES ITS WAY INTO OUR AREA BY TUESDAY...WHICH SHOULD BE JUST ABOUT THE COOLEST HIGH FOR THE LONG TERM BEFORE A BIT OF A REBOUND OCCURS FOR WEDNESDAY. THIS REBOUND OCCURS AHEAD OF A DIGGING MEAN LONG TROUGH OVER THE ROCKY MOUNTAINS WHICH WILL BE MOVING EAST. && .GID WATCHES/WARNINGS/ADVISORIES... NE...WIND ADVISORY FROM 11 AM THIS MORNING TO 6 PM CST THIS EVENING FOR NEZ039>041-046>049-060>064-072>077-082>087. KS...NONE. && $$ SHORT TERM...PFANNKUCH LONG TERM/AVIATION...HEINLEIN
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
529 AM CST THU FEB 14 2013 .UPDATE... .AVIATION... SCATTERED MVFR WILL SPREAD INTO NRN NEB THIS AFTN WITH THE PASSAGE OF AN ARCTIC FRONT CURRENTLY AT 11Z NEAR KSDY. SCATTERED SNOW SHOWERS AND MVFR WILL ACCOMPANY THE FRONT. MVFR AND ISOLATED SNOW SHOWERS MAY PERSIST TONIGHT ACROSS THE NORTH. ELSEWHERE MOSTLY VFR IS EXPECTED WITH ISOLATED RAIN OR SNOW SHOWERS DURING THE DAY TODAY. WINDS WILL INCREASE THIS AFTERNOON TO 32025G40KT AND DECREASE AT SUNSET. && .PREV DISCUSSION... /ISSUED 328 AM CST THU FEB 14 2013/ DISCUSSION... NEAR TERM...TODAY AND TONIGHT. SCATTERED SNOW SHOWERS DEVELOP TODAY THROUGH THIS EVENING WITH THE PASSAGE OF AN ARCTIC FRONT. WINDS AHEAD AND BEHIND THE FRONT SHOULD REACH WIND ADVISORY CRITERIA. STEEP LAPSE RATES TO 600-700MB SUPPORT THE WIND AND CONVECTIVE PCPN. THE RUC AND OTHER MODELS SUPPORT STRATUS WHICH COULD PERSIST INTO TONIGHT ACROSS THE NORTH. TEMPERATURES THIS AFTN WILL BE CONTINGENT ON THE FRONTAL PASSAGE. THE HRRR AND RAP MODELS SHOWS 40S SOUTH AND 30S NORTH. A BLEND OF GEM AND NAM WAS THE BASIS FOR THE FCST WHICH GIVES A SIMILAR EFFECT. NEITHER THE RAP OR HRRR FCST MAX TEMPS...JUST HOURLY. WINDS AND TEMPS DROP TONIGHT AS THE ARCTIC HIGH BUILDS THROUGH THE UPPER MISSOURI BASIN AND PACIFIC HIGH PRESSURE BUILDS THROUGH THE HIGH PLAINS. ALL MODELS SHOW LOW PRESSURE DEVELOPING ACROSS ERN SD SIGNALING A REINFORCING COLD FRONT FOR FRIDAY. SHORT TERM...12Z FRIDAY THROUGH 12Z SUNDAY. BROAD CYCLONIC FLOW ACROSS THE NORTHERN AND CENTRAL PLAINS WILL REMAIN ON FRIDAY...WITH AN ADDITIONAL SHORTWAVE IMPULSE DIVING SOUTH THROUGH AMPLIFIED NORTHWESTERLY FLOW. DUE TO FAVORABLE UPPER JET DYNAMICS AND THE FACT THAT LOW LEVEL LAPSE RATES REMAIN STEEP WITHIN A SATURATED DENDRITIC LAYER...WILL MAINTAIN -SN AND FLURRIES ACROSS THE ENTIRE CWA ON FRIDAY. THE IMPULSE QUICKLY DROPS TO THE SOUTH WITH A WARM FRONT PUSHING WEST TO EAST FRIDAY NIGHT INTO SATURDAY...TEMPERATURES SHOULD START TO MODERATE...WITH HIGHS APPROACHING 50 SOUTH OF INTERSTATE 80 AND ACROSS THE EASTERN PANHANDLE. LONG TERM...12Z SUNDAY AND BEYOND. SHORTWAVE RIDGING ACROSS THE REGION WILL GIVE WAY TO PROGRESSIVE ZONAL FLOW AS A TROUGH ADVANCES ACROSS THE NORTHERN ROCKIES ONTO THE PLAINS. IN ADVANCE OF THE TROUGH...SURFACE LOW PRESSURE OVER THE HIGH PLAINS WILL DEEPEN THROUGHOUT THE DAY ON SUNDAY...ALLOWING FOR WESTERLY TO SOUTHWESTERLY WIND WHICH WILL HELP WARM TEMPERATURES. LOOKING AT MID TO UPPER 50S GENERALLY OVER THE SOUTHERN HALF OF THE CWA...AND WHERE SNOW REMAINS...MID 40S SEEM PLAUSIBLE. THE WAVE WILL EVENTUALLY DRAG A COLD FRONT THROUGH THE CWA EARLY ON MONDAY...AT THIS TIME NOT SEEING MUCH SUPPORT FOR PRECIPITATION PRODUCTION...BUT HIGHS WILL BE SOME 15-20 DEGREES COOLER. THE NEXT IN LINE OF SHORTWAVE RIDGING ARRIVES EARLY TO MIDDLE NEXT WEEK...HOWEVER WE WILL BE RECYCLING SOME COLDER AIR BACK FROM THE EAST...SO A WARM UP MAY BE MODERATED SOMEWHAT. ATTENTION THEN TURNS TO THE NEXT SIGNIFICANT TROUGH WHICH SHOULD BE LOCATED ACROSS THE GREAT BASIN AROUND 12Z ON WEDNESDAY. SURPRISINGLY...THERE IS BETTER THAN AVERAGE CONTINUITY/AGREEMENT BETWEEN THE LONGER RANGE SOLUTIONS AND SEVERAL ENSEMBLE MEMBERS...WHICH SUGGEST A POTENTIALLY SIGNIFICANT STORM FOR THE CWA...SIMILAR TO THE TRACK OF LAST WEEKEND/S SYSTEM. ONE DIFFERENCE IS THAT THE MODELS ARE SHOWING SOME NEGATIVELY TILTED TENDENCIES WITH THE OVERALL SYSTEM...ALLOWING FOR A MUCH LONGER PERIOD OF QPF ACROSS THE CWA...INTERESTING. THAT BEING SAID...THE POTENTIAL SYSTEM IS SEVEN DAY/S OUT...SO WON`T GET TOO EXCITED YET. THUS WILL LIMIT POPS AT 30 PERCENT /OR LESS/ FOR NOW. AVIATION... MVFR WILL SPREAD INTO NRN NEB THIS AFTN WITH THE PASSAGE OF AN ARCTIC FRONT CURRENTLY AT 08Z NEAR KGGW. SCATTERED SNOW SHOWERS WILL ACCOMPANY THE FRONT. MVFR AND ISOLATES SNOW SHOWERS MAY PERSIST TONIGHT ACROSS THE NORTH. ELSEWHERE MOSTLY VFR IS EXPECTED WITH ISOLATED RAIN OR SNOW SHOWERS DURING THE DAY TODAY. && .LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY FROM 10 AM CST /9 AM MST/ THIS MORNING TO 6 PM CST /5 PM MST/ THIS EVENING FOR NEZ004>010-022>029-035>038-056>059- 069>071-094. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION....CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
328 AM CST THU FEB 14 2013 .DISCUSSION... NEAR TERM...TODAY AND TONIGHT. SCATTERED SNOW SHOWERS DEVELOP TODAY THROUGH THIS EVENING WITH THE PASSAGE OF AN ARCTIC FRONT. WINDS AHEAD AND BEHIND THE FRONT SHOULD REACH WIND ADVISORY CRITERIA. STEEP LAPSE RATES TO 600-700MB SUPPORT THE WIND AND CONVECTIVE PCPN. THE RUC AND OTHER MODELS SUPPORT STRATUS WHICH COULD PERSIST INTO TONIGHT ACROSS THE NORTH. TEMPERATURES THIS AFTN WILL BE CONTINGENT ON THE FRONTAL PASSAGE. THE HRRR AND RAP MODELS SHOWS 40S SOUTH AND 30S NORTH. A BLEND OF GEM AND NAM WAS THE BASIS FOR THE FCST WHICH GIVES A SIMILAR EFFECT. NEITHER THE RAP OR HRRR FCST MAX TEMPS...JUST HOURLY. WINDS AND TEMPS DROP TONIGHT AS THE ARCTIC HIGH BUILDS THROUGH THE UPPER MISSOURI BASIN AND PACIFIC HIGH PRESSURE BUILDS THROUGH THE HIGH PLAINS. ALL MODELS SHOW LOW PRESSURE DEVELOPING ACROSS ERN SD SIGNALING A REINFORCING COLD FRONT FOR FRIDAY. SHORT TERM...12Z FRIDAY THROUGH 12Z SUNDAY. BROAD CYCLONIC FLOW ACROSS THE NORTHERN AND CENTRAL PLAINS WILL REMAIN ON FRIDAY...WITH AN ADDITIONAL SHORTWAVE IMPULSE DIVING SOUTH THROUGH AMPLIFIED NORTHWESTERLY FLOW. DUE TO FAVORABLE UPPER JET DYNAMICS AND THE FACT THAT LOW LEVEL LAPSE RATES REMAIN STEEP WITHIN A SATURATED DENDRITIC LAYER...WILL MAINTAIN -SN AND FLURRIES ACROSS THE ENTIRE CWA ON FRIDAY. THE IMPULSE QUICKLY DROPS TO THE SOUTH WITH A WARM FRONT PUSHING WEST TO EAST FRIDAY NIGHT INTO SATURDAY...TEMPERATURES SHOULD START TO MODERATE...WITH HIGHS APPROACHING 50 SOUTH OF INTERSTATE 80 AND ACROSS THE EASTERN PANHANDLE. LONG TERM...12Z SUNDAY AND BEYOND. SHORTWAVE RIDGING ACROSS THE REGION WILL GIVE WAY TO PROGRESSIVE ZONAL FLOW AS A TROUGH ADVANCES ACROSS THE NORTHERN ROCKIES ONTO THE PLAINS. IN ADVANCE OF THE TROUGH...SURFACE LOW PRESSURE OVER THE HIGH PLAINS WILL DEEPEN THROUGHOUT THE DAY ON SUNDAY...ALLOWING FOR WESTERLY TO SOUTHWESTERLY WIND WHICH WILL HELP WARM TEMPERATURES. LOOKING AT MID TO UPPER 50S GENERALLY OVER THE SOUTHERN HALF OF THE CWA...AND WHERE SNOW REMAINS...MID 40S SEEM PLAUSIBLE. THE WAVE WILL EVENTUALLY DRAG A COLD FRONT THROUGH THE CWA EARLY ON MONDAY...AT THIS TIME NOT SEEING MUCH SUPPORT FOR PRECIPITATION PRODUCTION...BUT HIGHS WILL BE SOME 15-20 DEGREES COOLER. THE NEXT IN LINE OF SHORTWAVE RIDGING ARRIVES EARLY TO MIDDLE NEXT WEEK...HOWEVER WE WILL BE RECYCLING SOME COLDER AIR BACK FROM THE EAST...SO A WARM UP MAY BE MODERATED SOMEWHAT. ATTENTION THEN TURNS TO THE NEXT SIGNIFICANT TROUGH WHICH SHOULD BE LOCATED ACROSS THE GREAT BASIN AROUND 12Z ON WEDNESDAY. SURPRISINGLY...THERE IS BETTER THAN AVERAGE CONTINUITY/AGREEMENT BETWEEN THE LONGER RANGE SOLUTIONS AND SEVERAL ENSEMBLE MEMBERS...WHICH SUGGEST A POTENTIALLY SIGNIFICANT STORM FOR THE CWA...SIMILAR TO THE TRACK OF LAST WEEKEND/S SYSTEM. ONE DIFFERENCE IS THAT THE MODELS ARE SHOWING SOME NEGATIVELY TILTED TENDENCIES WITH THE OVERALL SYSTEM...ALLOWING FOR A MUCH LONGER PERIOD OF QPF ACROSS THE CWA...INTERESTING. THAT BEING SAID...THE POTENTIAL SYSTEM IS SEVEN DAY/S OUT...SO WON`T GET TOO EXCITED YET. THUS WILL LIMIT POPS AT 30 PERCENT /OR LESS/ FOR NOW. && .AVIATION... MVFR WILL SPREAD INTO NRN NEB THIS AFTN WITH THE PASSAGE OF AN ARCTIC FRONT CURRENTLY AT 08Z NEAR KGGW. SCATTERED SNOW SHOWERS WILL ACCOMPANY THE FRONT. MVFR AND ISOLATES SNOW SHOWERS MAY PERSIST TONIGHT ACROSS THE NORTH. ELSEWHERE MOSTLY VFR IS EXPECTED WITH ISOLATED RAIN OR SNOW SHOWERS DURING THE DAY TODAY. && .LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY FROM 10 AM CST /9 AM MST/ THIS MORNING TO 6 PM CST /5 PM MST/ THIS EVENING FOR NEZ004>010-022>029-035>038-056>059- 069>071-094. && $$ SHORT TERM/LONG TERM...JACOBS NEAR TERM/AVIATION....CDC
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1043 AM MST THU FEB 14 2013 .UPDATE...CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER THE WESTERN GREAT LAKES...WITH A TIGHT PRESSURE GRADIENT IN PLACE TO THE WEST ACROSS THE NORTHERN PLAINS. UPPER LEVEL ANALYSIS SHOWS LOW OVER HUDSON BAY...WITH TROF ACROSS THE CENTRAL AND EASTERN CONUS. STRONG JET FROM WESTERN CANADA THROUGH THE CENTRAL PLAINS IS BRINGING NUMEROUS WEAK DISTURBANCES ACROSS THE REGION. CURRENT ONE IS MOVING ACROSS THE NORTHERN HIGH PLAINS NOW. SKIES ARE MAINLY CLOUDY ACROSS THE AREA...WITH SOME BREAKS ACROSS WESTERN SD. KUDX RADAR SHOWING BANDS OF SNOW SHOWERS DEVELOPING PARALLEL TO THE FLOW ACROSS FAR NORTHEASTERN WY AND WESTERN SD. THE HEAVIEST SHOWERS CONTINUE TO BE ACROSS THE NORTHERN INTO WEST CENTRAL BLACK HILLS...WHERE UP TO 6 INCHES HAS FALLEN IN THE FAVORED HIGHER ELEVATIONS SINCE LATE YESTERDAY...ESPECIALLY NORTHWESTERN PORTIONS OF THE BLACK HILLS. WINDS INCREASED AGAIN ACROSS THE PLAINS EARLY THIS MORNING...WITH SOME GUSTS IN THE 50 TO 60 MPH RANGE FROM 2WX TO RAP EARLIER THIS MORNING. TEMPS ARE MOSTLY IN THE MID 20S TO LOWER 30S. HAVE ONLY MADE MINOR CHANGES TO THE FORECAST FOR THE REST OF TODAY AS SNOW SHOWERS CONTINUE TO DEVELOP AND TRACK SOUTHEAST ACROSS THE AREA THROUGH THE AFTERNOON. LOW LEVEL INSTABILITY AND MOISTURE IS SUFFICIENT FOR SCATTERED TO NUMEROUS COVERAGE OF SHOWERS FOR MOST OF THE AREA. ADDITIONAL SNOWFALL AMOUNTS OF 1 TO 3 INCHES ARE EXPECTED ACROSS THE NORTHERN BLACK HILLS AND BEAR LODGE MTS...WITH THE HIGHEST AMOUNTS OVER NORTHWEST FACING SLOPES. ANY ACCUMULATIONS ACROSS THE PLAINS WILL GENERALLY BE LESS THAN AN INCH. SNOW SHOWERS WILL DECREASE IN COVERAGE ACROSS THE AREA LATE THIS AFTERNOON AND EVENING AS INSTABILITY DIMINISHES. THE COMBINATION OF SNOW SHOWERS AND WIND WILL BRIEFLY PRODUCE LOW VISIBILITIES ACROSS THE PLAINS. THE STRONG WINDS ACROSS THE PLAINS WILL CONTINUE INTO THE AFTERNOON...BUT START TO DIMINISH AFTER 21Z AS BEST PRESSURE RISES SHIFT EAST AND PRESSURE GRADIENT WEAKENS. TEMPERATURES WILL REMAIN NEARLY STEADY IN MOST AREAS...MID 20S TO MID 30S. && .AVIATION...18Z TAFS EXPECT SCT CONVECTIVE SHSN OVER THE AREA TODAY WITH LOCALIZED IFR CIGS/VSBYS. SHSN ACTIVITY WILL WANE SOME TONIGHT...EXCEPT OVER THE NORTHERN BLACK HILLS. && PREV DISCUSSION... /ISSUED 349 AM MST THU FEB 14 2013/ DISCUSSION...UPPER LEVEL ANALYSIS HAS BROAD TROF OVER SOUTH CENTRAL CANADA WITH RIDGE JUST OFF THE WEST COAST. IN BETWEEN...FAST NORTHWEST FLOW IS PRESENT ACROSS THE NORTHERN ROCKIES AND PLAINS WITH A 120KT JET DRIVING SEVERAL WEAK SHORTWAVES THROUGH MONTANA INTO EASTERN WYOMING AND WESTERN SOUTH DAKOTA. SKIES ARE MOSTLY CLOUDY WITH SOME SNOW CROSSING NORTHEAST WYOMING AND THE BLACK HILLS AT THE MOMENT. AT THE SURFACE...LOW PRESSURE IS LOCATED ACROSS CENTRAL NORTH DAKOTA AND EASTERN SOUTH DAKOTA...WITH HIGH PRESSURE ACROSS THE NORTHERN AND CENTRAL ROCKIES. TIGHT PRESSURE GRADIENT REMAINS ACROSS WESTERN SOUTH DAKOTA...STILL PRODUCING WINDY CONDITIONS. TEMPERATURES RANGE FROM THE 20S TO LOWER 30S. FOR TODAY...CYCLONIC FLOW ALOFT REMAINS OVER THE AREA...WITH SHORTWAVE ENERGY CONTINUING TO BRING SNOW TO MUCH OF THE AREA. GREATEST CHANCES WILL BE OVER NORTHWEST SOUTH DAKOTA...AND ALSO THE NORTHERN BLACK HILLS WHERE UPSLOPE ENHANCEMENT IS EXPECTED TO CONTINUE. VERY GUSTY WINDS WILL CONTINUE THROUGH THE DAY AS PRESSURE GRADIENT REMAINS TIGHT BEHIND SURFACE LOW. SURFACE LOW SHIFTS EAST THIS AFTERNOON...ALLOWING GRADIENT TO RELAX...AND WINDS TO SUBSIDE LATE IN THE AFTERNOON. TEMPERATURES WILL BE MUCH COOLER TODAY AS CANADIAN HIGH PRESSURE SETTLES IN. FOR FRIDAY...SNOW CHANCES LINGER THROUGH THE DAY...MAINLY OVER THE WESTERN CWA...AS REGION REMAINS UNDER WEAK CYCLONIC FLOW ALOFT. MODELS CONTINUE TO INDICATE UPSLOPE ENHANCEMENT THROUGH THE DAY...THOUGH IT SHOULD COME TO AN END BY EVENING AS MOISTURE DIMINISHES. TEMPERATURES WILL REMAIN BELOW AVERAGE ON FRIDAY. ON SATURDAY...WESTERN UPPER RIDGE FINALLY PUSHES ACROSS THE NORTHERN ROCKIES INTO THE NORTHERN PLAINS. DRY AND VERY MILD CONDITIONS ARE EXPECTED...WITH HIGH TEMPERATURES IN THE 40S TO LOWER 50S. EXTENDED...THE MODELS ARE IN GOOD AGREEMENT WITH THE FORECAST FOR A MODERATELY STRONG TROUGH CROSSING THE NORTHERN PLAINS SUNDAY NIGHT THROUGH MONDAY NIGHT. THE SURFACE LOW IS EXPECTED TO DROP THROUGH EASTERN NORTH DAKOTA PRODUCING A WRAP AROUND BAND OF POST FRONTAL PRECIP OVER THE WESTERN DAKOTAS. THE NEXT SYSTEM WHICH IS FORECAST TO CROSS THE CENTRAL PLAINS WEDNESDAY AND THURSDAY IS POSITIONED TO DEVELOP A BROAD AREA OF UPWARD MOTION OVER THE FORECAST AREA... ESPECIALLY THE EASTERN SLOPES OF THE BLKHLS AND SOUTH CENTRAL SOUTH DAKOTA. THIS MIDWEEK SYSTEM IS ALSO ON A BETTER TRAJECTORY FOR TAPPING INTO GULF MOISTURE. TEMPERATURES WILL DROP TO BELOW NORMALS AFTER SUNDAY AND THEN CONTINUE TO COOL A FEW MORE DEGREES DURING MID WEEK. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR CENTRAL BLACK HILLS-NORTHERN BLACK HILLS. WIND ADVISORY UNTIL 5 PM MST /6 PM CST/ THIS AFTERNOON FOR BENNETT-BUTTE-CUSTER CO PLAINS-FALL RIVER-HAAKON-HARDING- HERMOSA FOOT HILLS-JACKSON-MELLETTE-NORTHERN FOOT HILLS- NORTHERN MEADE CO PLAINS-PENNINGTON CO PLAINS-PERKINS-RAPID CITY-SHANNON-SOUTHERN FOOT HILLS-SOUTHERN MEADE CO PLAINS- STURGIS/PIEDMONT FOOT HILLS-TODD-TRIPP-ZIEBACH. WY...WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR WYOMING BLACK HILLS. && $$ SHORT TERM...26 LONG TERM....WFO UNR AVIATION...HELGESON
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
944 PM EST FRI FEB 15 2013 .DISCUSSION...RAIN AND SNOW SHOWERS MAINLY OVER THE NORTHEASTERN THIRD OF THE REGION...ACROSS SOUTHWEST VIRGINIA AND NORTHEAST TENNESSEE AT THIS TIME. RUC AND NAM SHOW MOST PRECIPITATION ENDING BY 06Z AS MAIN SHORTWAVE ASSOCIATED WITH TODAYS COLD FRONT MOVES FARTHER EAST IN NC. UPDATED ZONES TO LOWER POPS A LITTLE MORE SOUTH AND WEST FOR THE REST OF THE NIGHT. TEMPERATURES FALLING SLOWLY SO CURRENT LOWS LOOK GOOD. MAY GET SOME CLEARING WEST BEFORE MORNING SO LOWS THERE MAY BE A LITTLE TOO WARM. WINDS HAVE DECREASED ACROSS THE FORECAST AREA SO WIND CHILLS NOT THAT SIGNIFICANT. UPDATED FORECAST SENT. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 32 43 23 47 29 / 10 10 0 0 0 KNOXVILLE MCGHEE TYSON AIRPORT, TN 30 38 20 43 28 / 20 20 10 0 0 OAK RIDGE, TN 30 41 20 44 26 / 20 20 10 0 0 TRI CITIES AIRPORT, TN 28 37 17 35 21 / 30 30 20 10 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ TD
AREA FORECAST DISCUSSION...UPDATED
NWS BLACKSBURG VA
955 PM EST FRI FEB 15 2013 .SYNOPSIS... A COLD FRONT MOVES EAST OF THE REGION OVERNIGHT...FOLLOWED BY A STRONGER ARCTIC COLD FRONT SATURDAY NIGHT. MEANWHILE...AN AREA OF LOW PRESSURE WILL FORM ALONG THE FIRST BOUNDARY AND MOVE OFF THE CAROLINA COAST BEFORE TURNING NORTH LATER SATURDAY. HIGH PRESSURE ARRIVES SUNDAY NIGHT BEFORE ANOTHER COLD FRONT ENTERS THE APPALACHIANS LATE MONDAY NIGHT. && .NEAR TERM /THROUGH SATURDAY/... AS OF 950 PM EST FRIDAY... BASED ON ADDED SNOWFALL REPORTS OF AROUND 3 INCHES IN TAZEWELL CTY ALONG WITH DEVELOPING SLICK ROAD CONDITIONS...WENT AHEAD WITH A WINTER WEATHER ADVISORY THROUGH 4 AM FOR TAZEWELL...MERCER AND BLAND CTYS WHERE COULD SEE UP TO 4 INCHES OF SNOW BEFORE THINGS TAPER OFF TO FLURRIES. AS OF 845 PM EST FRIDAY... PERSISTENT BAND OF SNOW REMAINS ACROSS FAR SW VA INTO SE WVA ALONG THE LEADING EDGE OF THE DEEPENING 5H TROF TO THE WEST AND UNDER A WEAK SHORTWAVE AHEAD OF THE MAIN UPPER COLD POOL. WARM SURFACES FROM EARLIER TODAY HAVE APPARENTLY LIMITED ACCUMULATIONS DESPITE SEVERAL HOURS OF DECENT SNOWFALL WITH TOTALS OF 1-2 INCHES REPORTED MAINLY ON GRASSY SURFACES. SINCE APPEARS WILL BE TAPERING SHORTLY WONT HOIST AN ADVISORY YET UNLESS HEAVIER BANDS PERSIST LONGER. OTRW LATEST RAP AND LOCAL RNK WRF SHOW THIS BAND OF SNOW FINALLY WEAKENING BEFORE MIDNIGHT AS ENERGY SHIFTS EAST AND THE 85H FLOW TURNS MORE NNW. THUS KEEPING IN A FEW MORE HOURS OF CAT/LIKELY POPS THERE BEFORE DIMINISHING AFTER MIDNIGHT. OTRW COLD FRONT NOW ENTERING THE PIEDMONT WITH A FEW RAIN SHOWER BANDS ALONG IT OVER THE SE IN STRONG SW FLOW ALOFT DEPICTED OFF EVENING SOUNDINGS. EXPECT THIS RAINFALL TO AFFECT AREAS MAINLY EAST OF THE BLUE RIDGE BEFORE THE FRONT FINALLY GETS FAR ENOUGH EAST OF THE REGION TO SUPPORT A LITTLE BETTER DOWNSLOPING IN THE NEXT FEW HOURS. THUS THINKING WILL SEE A LULL IN PRECIP FOR THE MOST PART DURING THE EARLY MORNING HOURS WITH THE FRONT TO THE SE...ONLY WEAK UPSLOPE OVER THE WEST...AND LITTLE SUPPORT ALOFT AS WE SLIDE IN BETWEEN UPPER IMPULSES LATER TONIGHT. THIS IN LINE WITH POPS FROM EARLIER FOR AFTER MIDNIGHT SO ONLY TWEAKED POP COVERAGE LATER ON. HAVE SEEN LITTLE SNOW IN THE ADVISORY AREA BUT LEAVING HEADLINES AS IS FOR NOW. TEMPS SLOW TO FALL OUT EAST BUT WILL GET INTO BETTER COLD ADVECTION SHORTLY WITH THE LAV MOS LOOKING TOO WARM MOST SPOTS OVERNIGHT. PREVIOUS DISCUSSION... A MORE POTENT UPPER LEVEL WAVE PUSHING INTO THE CENTRAL PLAINS THIS AFTERNOON WILL MOVE ACROSS THE CAROLINAS ON SATURDAY...WHICH SPINS UP A SFC LOW OFF THE NC COAST. MODELS SHOW GOOD 700MB FRONTOGENESIS FORMING IN ADVANCE OF THIS SYSTEM...SUGGESTING HEAVY BANDS OF PRECIP WILL DEVELOP ACROSS NC AND IN THE EASTERN PORTION OF OUR FORECAST AREA. FORECAST SOUNDINGS SUGGEST TEMPS ALOFT WILL SUPPORT SNOW...OR A RAIN/SNOW MIX. DYNAMIC COOLING WITH THIS STRONG SYSTEM SHOULD KEEP MOST OF THE PRECIP IN THE FORM OF SNOW. SOME FACTORS THAT COULD LIMIT SNOW ACCUMULATION ARE THE WARM GROUND TEMPS AND THE FACT OUR AREA WILL BE ON THE NORTHWEST SIDE OF THE BEST LIFT. IN FACT...THE GFS IS AN OUTLIER WITH THE WESTERN EXTENT OF THE PRCIP SHIELD...AND A SLIGHTLY MORE EASTERN TRACK...AS SHOWN BY THE 12Z ECMWF KEEPS THE HEAVIEST AMOUNTS OUT OF FORECAST AREA. STILL...WILL ISSUE WINTER WEATHER ADVISORIES FOR THE NC MOUNTAINS FOR NEAR ADVISORY CRITERIA IN HIGHER ELEVATIONS...BUT LESS AMOUNTS TO THE EAST AND NO HEADLINES. AS THE SFC LOW DEEPENS...WINDS WILL INCREASE FROM THE NORTHWEST AND UPSLOPE SNOW SHOWERS WILL AGAIN DEVELOP ACROSS SOUTHEAST WEST VIRGINIA. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... AS OF 408 PM EST FRIDAY... LOW PRESSURE MOVING ALONG TONIGHT`S COLD FRONT SATURDAY WILL BE MOVING FAR ENOUGH AWAY FROM OUR AREA TO PULL ITS PRECIP SHIELD JUST OUT OF OUR EXTREME EASTERN COUNTIES EARLY SATURDAY NIGHT. DEPENDING UPON HOW DEEP THIS LOW TURNS OUT TO BE...SNOW MAY HOLD ALONG THESE COUNTIES A LITTLE LONGER THAN CURRENTLY FORECAST. ARCTIC BOUNDARY ARRIVING WILL GENERATE UPSLOPE SNOW SHOWERS AGAIN SATURDAY NIGHT...WITH ENOUGH MOISTURE TO POSSIBLY DELIVER SOME SNOW SHOWERS INTO THE NEW RIVER VALLEY. AS AN UPPER LEVEL DISTURBANCE LEAVES AFTER MIDNIGHT INTO SUNDAY MORNING...MOISTURE DRIES OUT RAPIDLY AND SNOW SHOWERS WILL BE MORE CONFINED TO SE WEST VA. EXPECTING THE GREATEST COVERAGE OF SNOW SHOWERS AROUND 6Z/1AM SUNDAY. UP TO 4" MAY FALL ACROSS WESTERN GREENBRIER WITH AN INCH OR TWO DOWN INTO BLF AND SIMILAR LOCATIONS ABOVE 2500 FEET. WIND DIRECTION SHOULD ALSO DELIVER SOME SNOW BANDS INTO NW NC WHERE AN INCH OR LESS IS EXPECTED BUT 2" ABOVE 3500 FEET. AS CLOUDS ARE REMOVED AND BETTER MIXING OCCURS ADVISORY CRITERIA WIND GUSTS ARE LIKELY ASHE/WATAUGA/GRAYSON AND A HIGH WIND WATCH MAY NEED TO BE CONSIDERED. AGAIN...MOS TEMPS LOOK TOO WARM WITH A SHALLOW ARCTIC AIRMASS SO USED SOME OF THE COLDER VALUES. SINGLE DIGITS DEWPOINTS AND RELAXING OF WIND WILL ALLOW DECOUPLING AND WIDESPREAD LOWS IN THE MIDDLE TEENS SUNDAY NIGHT. UPPER TROUGH LEAVES MONDAY WITH QUICK WAA...BUT A LOW MOVING INTO THE GREAT LAKES WILL DRAG A FRONT AND PRECIP ACROSS THE REGION LATE MONDAY NIGHT...WITH EVAP COOLING LIKELY PRODUCING A QUICK SHOT OF SLEET AND MAYBE SOME FREEZING RAIN ACROSS GREENBRIER INITIALLY. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 350 PM EST FRIDAY... HIGH PRESSURE DRIFTS OFF THE SOUTHEAST COAST ALLOWING A COLD FRONT TO PASS OVER THE REGION TUESDAY. A WINTRY MIX OF RAIN/SNOW/SLEET MAY STILL BE FALLING ACROSS THE GREENBRIER VALLEY AND ALLEGHANY HIGHLANDS TUESDAY MORNING. TEMPERATURES WARM BY MID MORNING WITH ALL PRECIPITATION FALLING AS RAIN. RAIN EXITS QUICKLY BY THE EVENING RUSH HOUR WITH WINDS INCREASING FROM THE WEST. WE WILL SEE CLEARING CONDITIONS FROM EAST TO WEST OVERNIGHT WITH SOME LINGERING CLOUDS/UPSLOPE SNOW SHOWERS INTO EARLY WEDNESDAY MORNING. TRAJECTORIES ARE NOT FAVORABLE FOR SIGNIFICANT UPSLOPE ACCUMULATIONS. MOISTURE COULD BE SHALLOW BY THE TIME THE COLDEST AIR ARRIVES TO JUST HAVE SPOTTY FREEZING DRIZZLE/SCATTERED FLURRIES. STRONG SOUTHWEST FLOW AHEAD OF THE FRONT MAY CREATE SOME WIND PROBLEMS ACROSS THE BLUEFIELD/RICHLANDS AREA TUESDAY MORNING. AS THE JET TRANSFERS EAST OF THE APPALACHIANS...STRONG WINDS MIXING TO THE SURFACE COULD PRODUCE ADVISORY GUSTS FOR THE REST OF THE AREA. WILL CONTINUE TO HIGHLIGHT IN THE HWO. STRONG AND GUSTY WINDS WILL ALSO FOLLOW THE FRONT WITH ANY ADVISORY GUSTS REMAINING ALONG THE HIGHER RIDGES ALONG THE BLUE RIDGE. HIGH PRESSURE WILL MOVE OVER THE REGION WEDNESDAY AFTERNOON WITH BREEZY CONDITIONS RELAXING BY THE EVENING. A WARM FRONT IS EXPECTED TO OVERRUN THIS SURFACE HIGH PRESSURE ON THURSDAY. LIGHT PRECIPITATION COULD START FALLING AS EARLY AS THURSDAY AFTERNOON (12Z GFS) OR START EARLY FRIDAY MORNING (12Z ECMWF). AS PRECIPITATION FALLS INTO THIS RIDGE...AN INSITU WEDGE WILL DEVELOP WITH A PERSISTENT EASTERLY FLOW THROUGH THE DAY FRIDAY. DESPITE THE TIMING DIFFERENCES...EVAPORATIVE COOLING IN BOTH MODELS OVERNIGHT SUPPORT FROZEN PRECIPITATION THURSDAY NIGHT INTO FRIDAY. GFS FORECAST SOUNDING SUGGESTING FREEZING RAIN. WITH UNCERTAINTY LOOMING LARGE THIS FAR OUT...WILL KEEP GRIDS SIMPLE WITH RAIN/SNOW. GFS IS ALSO BREAKING THE WEDGE QUICKLY FRIDAY MORNING. KEPT THE WEDGE IN LONGER AND COULD SEE IT BREAKING FRIDAY NIGHT VIA PRESSURE FALLS OVER THE OHIO VALLEY PER THE ECMWF. TEMPERATURES WILL HOVER AROUND NORMAL ON TUESDAY. CHILLY HIGH PRESSURE WILL TREND AFTERNOON TEMPERATURES BELOW NORMAL WEDNESDAY AND THURSDAY. TEMPERATURES WILL CONTINUE TO TREND COLDER FRIDAY WITH A WET COLD AIR DAMMING EVENT EXPECTED. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... AS OF 555 PM EST FRIDAY... COLD FRONT NOW CROSSING INTO WESTERN VIRGINIA WITH BROKEN AREAS OF LIGHT TO MODERATE RAIN/SNOW ALONG AND BEHIND THE BOUNDARY ATTM. LOCAL WRF SEEMS TO STILL HAVE THE BEST HANDLE SO WILL FOLLOW CLOSELY AND PUSH RAIN A BIT FARTHER EAST THIS EVENING TO PERHAPS KLYH SINCE GOOD DOWNSLOPE IS LAGGING THE FRONT. OTRW WILL HAVE PERIODIC MVFR TO IFR AT KBLF...AND MOSTLY MVFR AT KLWB AS EXPECTING BEST COVERAGE OF SNOW TO SLIDE SOUTH OF THAT AREA THIS EVENING. MAY ALSO INCLUDE A PERIOD OF MVFR AT BOTH KBCB/KROA WITH MOSTLY -SHRA AT ROANOKE AND PERHAPS A MIX TO SNOW AT KBCB BEFORE THINGS START TO TAPER OFF SOME LATER THIS EVENING. ELSW WILL MAINTAIN VFR OUT EAST PENDING JUST HOW FAR THE PRECIP GETS IN THE NEXT FEW HOURS. KLWB AND KBLF WILL TRANSITION TO AN UPSLOPING PCPN -SHSN EVENT AROUND MIDNIGHT IF NOT SOONER AND CONTINUE THROUGH TOMORROW. STILL LOOKING FOR MVFR CIGS/VSBYS AND EXPECT -SHSN TO BE LIGHT. KDAN IS INTERESTING FOR THE LATTER PORTION OF THE TAF PERIOD. LIFT DEVELOPING ON THE BACK SIDE OF THE DEEPENING LOW SLIDING OFF THE COAST WILL BEGIN TO DEVELOP A PRECIPITATION SHIELD. IT CURRENTLY LOOKS LIKE KDAN WILL BE ON THE EDGE OF THIS AND WILL KEEP SOME BORDERLINE VFR CIGS IN AFTER 12Z ALONG WITH SOME PCPN THAT MAY BE ALL SNOW DURING THE MORNING. LOW LEVEL WINDS DO NOT RAMP UP UNTIL LATER IN THE DAY SATURDAY IN RESPONSE TO DEEPENING OF COASTAL LOW SO DO NOT EXPECT SIGNIFICANT WINDS TO HAMPER AVIATION INTERESTS THROUGH THIS TAF PERIOD. EXTENDED AVIATION DISCUSSION... REASONING THROUGH THE EXTENDED PORTION STILL APPLIES AS PER PREVIOUS DISCUSSION: HIGH PRESSURE AND VFR CONDITIONS WILL RETURN TO THE MOUNTAINS BY SUNDAY. GOOD FLYING WEATHER SHOULD PREVAIL UNTIL TUESDAY...WHEN A NEW COLD FRONT COULD BRING SHOWERS WITH GUSTY WINDS ALONG WITH MVFR/IFR CEILINGS. VFR QUICKLY RETURNS ON WEDNESDAY WITH HIGH PRESSURE FOLLOWING THE FRONT. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WINTER WEATHER ADVISORY UNTIL 4 AM EST SATURDAY FOR VAZ007-010. NC...WINTER WEATHER ADVISORY UNTIL NOON EST SUNDAY FOR NCZ001-018. WV...WINTER WEATHER ADVISORY UNTIL 4 AM EST SATURDAY FOR WVZ042. && $$ SYNOPSIS...AMS/KM NEAR TERM...AMS/JH/PH SHORT TERM...KM LONG TERM...RCS AVIATION...AMS/JH/NF
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
918 PM EST FRI FEB 15 2013 .SYNOPSIS... A COLD FRONT MOVES EAST OF THE REGION OVERNIGHT...FOLLOWED BY A STRONGER ARCTIC COLD FRONT SATURDAY NIGHT. MEANWHILE...AN AREA OF LOW PRESSURE WILL FORM ALONG THE FIRST BOUNDARY AND MOVE OFF THE CAROLINA COAST BEFORE TURNING NORTH LATER SATURDAY. HIGH PRESSURE ARRIVES SUNDAY NIGHT BEFORE ANOTHER COLD FRONT ENTERS THE APPALACHIANS LATE MONDAY NIGHT. && .NEAR TERM /THROUGH SATURDAY/... AS OF 845 PM EST FRIDAY... PERSISTENT BAND OF SNOW REMAINS ACROSS FAR SW VA INTO SE WVA ALONG THE LEADING EDGE OF THE DEEPENING 5H TROF TO THE WEST AND UNDER A WEAK SHORTWAVE AHEAD OF THE MAIN UPPER COLD POOL. WARM SURFACES FROM EARLIER TODAY HAVE APPARENTLY LIMITED ACCUMULATIONS DESPITE SEVERAL HOURS OF DECENT SNOWFALL WITH TOTALS OF 1-2 INCHES REPORTED MAINLY ON GRASSY SURFACES. SINCE APPEARS WILL BE TAPERING SHORTLY WONT HOIST AN ADVISORY YET UNLESS HEAVIER BANDS PERSIST LONGER. OTRW LATEST RAP AND LOCAL RNK WRF SHOW THIS BAND OF SNOW FINALLY WEAKENING BEFORE MIDNIGHT AS ENERGY SHIFTS EAST AND THE 85H FLOW TURNS MORE NNW. THUS KEEPING IN A FEW MORE HOURS OF CAT/LIKELY POPS THERE BEFORE DIMINISHING AFTER MIDNIGHT. OTRW COLD FRONT NOW ENTERING THE PIEDMONT WITH A FEW RAIN SHOWER BANDS ALONG IT OVER THE SE IN STRONG SW FLOW ALOFT DEPICTED OFF EVENING SOUNDINGS. EXPECT THIS RAINFALL TO AFFECT AREAS MAINLY EAST OF THE BLUE RIDGE BEFORE THE FRONT FINALLY GETS FAR ENOUGH EAST OF THE REGION TO SUPPORT A LITTLE BETTER DOWNSLOPING IN THE NEXT FEW HOURS. THUS THINKING WILL SEE A LULL IN PRECIP FOR THE MOST PART DURING THE EARLY MORNING HOURS WITH THE FRONT TO THE SE...ONLY WEAK UPSLOPE OVER THE WEST...AND LITTLE SUPPORT ALOFT AS WE SLIDE IN BETWEEN UPPER IMPULSES LATER TONIGHT. THIS IN LINE WITH POPS FROM EARLIER FOR AFTER MIDNIGHT SO ONLY TWEAKED POP COVERAGE LATER ON. HAVE SEEN LITTLE SNOW IN THE ADVISORY AREA BUT LEAVING HEADLINES AS IS FOR NOW. TEMPS SLOW TO FALL OUT EAST BUT WILL GET INTO BETTER COLD ADVECTION SHORTLY WITH THE LAV MOS LOOKING TOO WARM MOST SPOTS OVERNIGHT. PREVIOUS DISCUSSION... A MORE POTENT UPPER LEVEL WAVE PUSHING INTO THE CENTRAL PLAINS THIS AFTERNOON WILL MOVE ACROSS THE CAROLINAS ON SATURDAY...WHICH SPINS UP A SFC LOW OFF THE NC COAST. MODELS SHOW GOOD 700MB FRONTOGENESIS FORMING IN ADVANCE OF THIS SYSTEM...SUGGESTING HEAVY BANDS OF PRECIP WILL DEVELOP ACROSS NC AND IN THE EASTERN PORTION OF OUR FORECAST AREA. FORECAST SOUNDINGS SUGGEST TEMPS ALOFT WILL SUPPORT SNOW...OR A RAIN/SNOW MIX. DYNAMIC COOLING WITH THIS STRONG SYSTEM SHOULD KEEP MOST OF THE PRECIP IN THE FORM OF SNOW. SOME FACTORS THAT COULD LIMIT SNOW ACCUMULATION ARE THE WARM GROUND TEMPS AND THE FACT OUR AREA WILL BE ON THE NORTHWEST SIDE OF THE BEST LIFT. IN FACT...THE GFS IS AN OUTLIER WITH THE WESTERN EXTENT OF THE PRCIP SHIELD...AND A SLIGHTLY MORE EASTERN TRACK...AS SHOWN BY THE 12Z ECMWF KEEPS THE HEAVIEST AMOUNTS OUT OF FORECAST AREA. STILL...WILL ISSUE WINTER WEATHER ADVISORIES FOR THE NC MOUNTAINS FOR NEAR ADVISORY CRITERIA IN HIGHER ELEVATIONS...BUT LESS AMOUNTS TO THE EAST AND NO HEADLINES. AS THE SFC LOW DEEPENS...WINDS WILL INCREASE FROM THE NORTHWEST AND UPSLOPE SNOW SHOWERS WILL AGAIN DEVELOP ACROSS SOUTHEAST WEST VIRGINIA. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... AS OF 408 PM EST FRIDAY... LOW PRESSURE MOVING ALONG TONIGHT`S COLD FRONT SATURDAY WILL BE MOVING FAR ENOUGH AWAY FROM OUR AREA TO PULL ITS PRECIP SHIELD JUST OUT OF OUR EXTREME EASTERN COUNTIES EARLY SATURDAY NIGHT. DEPENDING UPON HOW DEEP THIS LOW TURNS OUT TO BE...SNOW MAY HOLD ALONG THESE COUNTIES A LITTLE LONGER THAN CURRENTLY FORECAST. ARCTIC BOUNDARY ARRIVING WILL GENERATE UPSLOPE SNOW SHOWERS AGAIN SATURDAY NIGHT...WITH ENOUGH MOISTURE TO POSSIBLY DELIVER SOME SNOW SHOWERS INTO THE NEW RIVER VALLEY. AS AN UPPER LEVEL DISTURBANCE LEAVES AFTER MIDNIGHT INTO SUNDAY MORNING...MOISTURE DRIES OUT RAPIDLY AND SNOW SHOWERS WILL BE MORE CONFINED TO SE WEST VA. EXPECTING THE GREATEST COVERAGE OF SNOW SHOWERS AROUND 6Z/1AM SUNDAY. UP TO 4" MAY FALL ACROSS WESTERN GREENBRIER WITH AN INCH OR TWO DOWN INTO BLF AND SIMILAR LOCATIONS ABOVE 2500 FEET. WIND DIRECTION SHOULD ALSO DELIVER SOME SNOW BANDS INTO NW NC WHERE AN INCH OR LESS IS EXPECTED BUT 2" ABOVE 3500 FEET. AS CLOUDS ARE REMOVED AND BETTER MIXING OCCURS ADVISORY CRITERIA WIND GUSTS ARE LIKELY ASHE/WATAUGA/GRAYSON AND A HIGH WIND WATCH MAY NEED TO BE CONSIDERED. AGAIN...MOS TEMPS LOOK TOO WARM WITH A SHALLOW ARCTIC AIRMASS SO USED SOME OF THE COLDER VALUES. SINGLE DIGITS DEWPOINTS AND RELAXING OF WIND WILL ALLOW DECOUPLING AND WIDESPREAD LOWS IN THE MIDDLE TEENS SUNDAY NIGHT. UPPER TROUGH LEAVES MONDAY WITH QUICK WAA...BUT A LOW MOVING INTO THE GREAT LAKES WILL DRAG A FRONT AND PRECIP ACROSS THE REGION LATE MONDAY NIGHT...WITH EVAP COOLING LIKELY PRODUCING A QUICK SHOT OF SLEET AND MAYBE SOME FREEZING RAIN ACROSS GREENBRIER INITIALLY. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 350 PM EST FRIDAY... HIGH PRESSURE DRIFTS OFF THE SOUTHEAST COAST ALLOWING A COLD FRONT TO PASS OVER THE REGION TUESDAY. A WINTRY MIX OF RAIN/SNOW/SLEET MAY STILL BE FALLING ACROSS THE GREENBRIER VALLEY AND ALLEGHANY HIGHLANDS TUESDAY MORNING. TEMPERATURES WARM BY MID MORNING WITH ALL PRECIPITATION FALLING AS RAIN. RAIN EXITS QUICKLY BY THE EVENING RUSH HOUR WITH WINDS INCREASING FROM THE WEST. WE WILL SEE CLEARING CONDITIONS FROM EAST TO WEST OVERNIGHT WITH SOME LINGERING CLOUDS/UPSLOPE SNOW SHOWERS INTO EARLY WEDNESDAY MORNING. TRAJECTORIES ARE NOT FAVORABLE FOR SIGNIFICANT UPSLOPE ACCUMULATIONS. MOISTURE COULD BE SHALLOW BY THE TIME THE COLDEST AIR ARRIVES TO JUST HAVE SPOTTY FREEZING DRIZZLE/SCATTERED FLURRIES. STRONG SOUTHWEST FLOW AHEAD OF THE FRONT MAY CREATE SOME WIND PROBLEMS ACROSS THE BLUEFIELD/RICHLANDS AREA TUESDAY MORNING. AS THE JET TRANSFERS EAST OF THE APPALACHIANS...STRONG WINDS MIXING TO THE SURFACE COULD PRODUCE ADVISORY GUSTS FOR THE REST OF THE AREA. WILL CONTINUE TO HIGHLIGHT IN THE HWO. STRONG AND GUSTY WINDS WILL ALSO FOLLOW THE FRONT WITH ANY ADVISORY GUSTS REMAINING ALONG THE HIGHER RIDGES ALONG THE BLUE RIDGE. HIGH PRESSURE WILL MOVE OVER THE REGION WEDNESDAY AFTERNOON WITH BREEZY CONDITIONS RELAXING BY THE EVENING. A WARM FRONT IS EXPECTED TO OVERRUN THIS SURFACE HIGH PRESSURE ON THURSDAY. LIGHT PRECIPITATION COULD START FALLING AS EARLY AS THURSDAY AFTERNOON (12Z GFS) OR START EARLY FRIDAY MORNING (12Z ECMWF). AS PRECIPITATION FALLS INTO THIS RIDGE...AN INSITU WEDGE WILL DEVELOP WITH A PERSISTENT EASTERLY FLOW THROUGH THE DAY FRIDAY. DESPITE THE TIMING DIFFERENCES...EVAPORATIVE COOLING IN BOTH MODELS OVERNIGHT SUPPORT FROZEN PRECIPITATION THURSDAY NIGHT INTO FRIDAY. GFS FORECAST SOUNDING SUGGESTING FREEZING RAIN. WITH UNCERTAINTY LOOMING LARGE THIS FAR OUT...WILL KEEP GRIDS SIMPLE WITH RAIN/SNOW. GFS IS ALSO BREAKING THE WEDGE QUICKLY FRIDAY MORNING. KEPT THE WEDGE IN LONGER AND COULD SEE IT BREAKING FRIDAY NIGHT VIA PRESSURE FALLS OVER THE OHIO VALLEY PER THE ECMWF. TEMPERATURES WILL HOVER AROUND NORMAL ON TUESDAY. CHILLY HIGH PRESSURE WILL TREND AFTERNOON TEMPERATURES BELOW NORMAL WEDNESDAY AND THURSDAY. TEMPERATURES WILL CONTINUE TO TREND COLDER FRIDAY WITH A WET COLD AIR DAMMING EVENT EXPECTED. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... AS OF 555 PM EST FRIDAY... COLD FRONT NOW CROSSING INTO WESTERN VIRGINIA WITH BROKEN AREAS OF LIGHT TO MODERATE RAIN/SNOW ALONG AND BEHIND THE BOUNDARY ATTM. LOCAL WRF SEEMS TO STILL HAVE THE BEST HANDLE SO WILL FOLLOW CLOSELY AND PUSH RAIN A BIT FARTHER EAST THIS EVENING TO PERHAPS KLYH SINCE GOOD DOWNSLOPE IS LAGGING THE FRONT. OTRW WILL HAVE PERIODIC MVFR TO IFR AT KBLF...AND MOSTLY MVFR AT KLWB AS EXPECTING BEST COVERAGE OF SNOW TO SLIDE SOUTH OF THAT AREA THIS EVENING. MAY ALSO INCLUDE A PERIOD OF MVFR AT BOTH KBCB/KROA WITH MOSTLY -SHRA AT ROANOKE AND PERHAPS A MIX TO SNOW AT KBCB BEFORE THINGS START TO TAPER OFF SOME LATER THIS EVENING. ELSW WILL MAINTAIN VFR OUT EAST PENDING JUST HOW FAR THE PRECIP GETS IN THE NEXT FEW HOURS. KLWB AND KBLF WILL TRANSITION TO AN UPSLOPING PCPN -SHSN EVENT AROUND MIDNIGHT IF NOT SOONER AND CONTINUE THROUGH TOMORROW. STILL LOOKING FOR MVFR CIGS/VSBYS AND EXPECT -SHSN TO BE LIGHT. KDAN IS INTERESTING FOR THE LATTER PORTION OF THE TAF PERIOD. LIFT DEVELOPING ON THE BACK SIDE OF THE DEEPENING LOW SLIDING OFF THE COAST WILL BEGIN TO DEVELOP A PRECIPITATION SHIELD. IT CURRENTLY LOOKS LIKE KDAN WILL BE ON THE EDGE OF THIS AND WILL KEEP SOME BORDERLINE VFR CIGS IN AFTER 12Z ALONG WITH SOME PCPN THAT MAY BE ALL SNOW DURING THE MORNING. LOW LEVEL WINDS DO NOT RAMP UP UNTIL LATER IN THE DAY SATURDAY IN RESPONSE TO DEEPENING OF COASTAL LOW SO DO NOT EXPECT SIGNIFICANT WINDS TO HAMPER AVIATION INTERESTS THROUGH THIS TAF PERIOD. EXTENDED AVIATION DISCUSSION... REASONING THROUGH THE EXTENDED PORTION STILL APPLIES AS PER PREVIOUS DISCUSSION: HIGH PRESSURE AND VFR CONDITIONS WILL RETURN TO THE MOUNTAINS BY SUNDAY. GOOD FLYING WEATHER SHOULD PREVAIL UNTIL TUESDAY...WHEN A NEW COLD FRONT COULD BRING SHOWERS WITH GUSTY WINDS ALONG WITH MVFR/IFR CEILINGS. VFR QUICKLY RETURNS ON WEDNESDAY WITH HIGH PRESSURE FOLLOWING THE FRONT. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...WINTER WEATHER ADVISORY UNTIL NOON EST SUNDAY FOR NCZ001-018. WV...NONE. && $$ SYNOPSIS...AMS/KM NEAR TERM...AMS/JH/PH SHORT TERM...KM LONG TERM...RCS AVIATION...AMS/JH/NF
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
532 PM CST FRI FEB 15 2013 .SHORT TERM...THROUGH MONDAY NIGHT 319 PM CST FRI FEB 15 2013 BENIGN WEATHER THROUGH THE WEEKEND LEADS INTO MONDAYS WEATHER SYSTEM WHICH WILL NEED TO BE WATCHED FOR CHANGES. MUCH LESS CLOUD ACROSS THE AREA TODAY THAN FORECAST WITH MIXING NOT DEEP ENOUGH TO FORM MUCH STRATOCUMULUS EXCEPT OVER NORTH-CENTRAL WI. LONGWAVE TROUGH AXIS CONTINUES EASTWARD PROGRESS WITH LAST OF SHORTWAVE TROUGH ENERGY COMING THROUGH TONIGHT AND EARLY SATURDAY. LATEST RAP AND WATER VAPOR HAS THIS BROAD CIRCULATION AXIS FROM KINL-KLBF...AND SURFACE LOW PRESSURE IN EASTERN NEB. CLOUD COVER OVER NWRN MN MOVING TOWARD THE AREA WILL ARRIVE THIS EVENING FOR A CLOUD PERIOD INTO SATURDAY MORNING. NOT TO CONFIDENT ON THE COVERAGE OF THIS CLOUD COMING IN...IT MAY BE MORE IN AREAS. HAVE LEFT A MENTION OF FLURRIES IN THIS WEAKLY LIFTED AIR MASS THROUGH NOON SATURDAY. AGGRESSIVE RIDGE BUILDING THEN TAKES PLACE LATER SATURDAY AND SUNDAY. UPSTREAM RAOB HEIGHT RISES SEEN ACROSS WRN CANADA WITH THIS PROGRESSIVE HIGHER AMPLITUDE RIDGE. HAVE COOLED THE LOW TEMPERATURES SUNDAY MORNING OVER CENTRAL WI WITH NEARLY CALM WINDS AND LITTLE CLOUD UNDER LOW-LEVEL RIDGING. THESE ARE BELOW MOS GUIDANCE BY ABOUT 5-7F. WARM ADVECTION WILL BEGIN TO RAISE TEMPERATURES SUNDAY AND THE FORCING DOES NOT SEEM SUFFICIENT TO CREATE PRECIPITATION PER CONSENSUS 15.12Z MODEL GUIDANCE. HOWEVER...THE WARM ADVECTION AND THERMAL RIBBON LIFTING ACROSS THE AREA WILL CREATE AN ARC OF CLOUDS ORIENTED NW-SE TO SHIFT NEWRD ACROSS THE AREA. HAVE INCREASED SKY COVER A BIT FOR SUNDAY...SOME FLURRIES MAY BE POSSIBLE BUT HAVE NOT INCLUDED THEM IN THE FORECAST. FAIRLY INTERESTING TROUGH TO SHIFT INTO THE AREA MONDAY. THE TROUGH IS CURRENTLY IN THE ERN PACIFIC APPROACHING 47N/140W PER GOES WATER VAPOR. MODEL GUIDANCE CONSENSUS FROM 15.12Z IS THAT THERE WILL NRN AND SRN ENERGY IN THIS TROUGH. THE SRN PIECE OF ENERGY IS HANDLED DIFFERENTLY BY THE LATEST GUIDANCE. THE 15.12Z NAM/SREF DEVELOP ONLY A WEAK CYCLONE VIA THE SRN ENERGY...WHILE THE GEM GLOBAL AND 15.00Z FIM MODEL ARE AGGRESSIVE WITH THE CYCLONE DEEPENING IT ALONG A KANSAS CITY TO MILWAUKEE TRACK...AND DROPPING A 4-8 INCH SNOW BAND ACROSS WI. 15.12Z ECMWF/GFS ARE SIMILAR AND OFFER A COMPROMISE BETWEEN THE TWO CAMPS WITH THE CYCLONE DEEPENING LATER...INTO MICHIGAN. HAVE GONE WITH THIS COMPROMISE ON TIMING AND INTENSITY. MONDAY WILL SEE A GULF SURGE OF MOISTURE IN THE SOUTHERLY FLOW... DEEPENING A SURFACE-BASED LAYER TO OVER 1 KM DEEP. THIS WILL BE PRE-FRONTAL IN THE SOUTHERLY FLOW AND WITHOUT DEEP CLOUD AND ICE...BUT ISENTROPIC LIFT OF 3-5 UB/S IN THE LAYER ...DZ/FZDZ WILL BE POSSIBLE. THE MOIST TONGUE IS MAINLY IN WI AND EAST AND THAT IS WHERE DZ/FZDZ CHANCES WILL BE BEST. TEMPERATURES WILL BE WARMING MONDAY WITH ABOVE FREEZING HIGHS AROUND I-90 AND SOUTH EXPECTED. THUS...DZ OR RAIN SHOWERS COULD BE FREEZING IN THE EARLY AFTERNOON IF ROADS DO NOT RESPOND TO WARMING. WITH QPFS LESS THAN 0.10 INCHES...WOULD EXPECT ONLY LIGHT ICING TO OCCUR. AS TROUGH SHIFTS EAST LATE MONDAY AND MONDAY EVENING...A TRANSITION TO SNOW WILL OCCUR FROM WEST TO EAST WITH SNOW AMOUNTS OF LESS THAN AN INCH. HAVE INCREASED PRECIPITATION CHANCES OVERALL...BUT WI LOOKS TO BE THE MAIN WEATHER AREA FOR THIS SYSTEM. THERE IS A CHANCE THIS COULD NEED AN ADVISORY IF FREEZING PRECIPITATION LOOKS MORE WIDESPREAD OR THE MORE AGGRESSIVE CYCLONE SOLUTION IN THE GEM SHOULD BECOME MORE PROBABLE. THE SPREAD IN THE CYCLOGENESIS SEEN FROM THE SRN ENERGY IN THE MODEL GUIDANCE SUGGESTS THIS IS AN UNSTABLE SYSTEM AND COULD LEAD TO FORECAST CHANGES. WILL TAKE A STEP UP IN OUR FORECAST VISIBILITY OF THIS SYSTEM. .LONG TERM...TUESDAY THROUGH FRIDAY 319 PM CST FRI FEB 15 2013 ACTIVE EXTENDED PERIOD SETTING UP WITH THE FOCUS ON A SHORT ARCTIC INTRUSION MID WEEK FOLLOWED BY THE POTENTIAL OF A WINTER STORM TO IMPACT THE UPPER MIDWEST NEXT THURSDAY NIGHT AND FRIDAY. GOING INTO TUESDAY...A LOT DEPENDS ON THE EVOLUTION AND PHASING OF THE STORM SYSTEM THAT IS EXPECTED TO TRACK THROUGH MONDAY AND MONDAY NIGHT...AND HOW MUCH ARCTIC AIR IS PULLED SOUTH IN ITS WAKE. 15.12Z GUIDANCE SHOWS SIMILAR SOLUTIONS FOR 850 MB TEMPERATURES TO PLUMMET AS LOW AS -15C TO -20C TUESDAY AND WEDNESDAY. STANDARDIZED ANOMALIES FOR THIS PERIOD RANGE FROM 1 TO 1.5 BELOW NORMAL AND WITH BROAD CYCLONIC FLOW ALOFT...IT WILL MAKE FOR A COUPLE COLD WINTER DAYS. HIGHS IN THE TEENS AND OVERNIGHT LOWS IN THE SINGLE DIGITS ABOVE ZERO...WITH OCCASIONAL LIGHT SNOW OR FLURRIES TUESDAY. THE COLD AIRMASS SETS THE STAGE FOR LATER IN THE WEEK AS A WESTERN CONUS TROUGH DEEPENS AND MOVES EAST. AS HAS BEEN ALLUDED TO IN PREVIOUS DISCUSSIONS...THE RUN-TO-RUN AND MODEL CONSISTENCY FOR THIS FEATURE REMAINS VERY HIGH. DETERMINISTIC MODELS STILL POINT FOR A SURFACE LOW TRACK THROUGH THE CENTRAL PLAINS TO NORTHERN ILLINOIS BY 12Z FRIDAY BRINGING WIDESPREAD PRECIPITATION TO THE ENTIRE AREA WITH A CLASSIC DEFORMATION BAND OF SNOW SETTING UP. LOOKING AT THE 15.12Z GFS ENSEMBLE...SURFACE LOW TRACK LOCATIONS VARY FROM EASTERN IOWA...SOUTHERN WISCONSIN...AND ILLINOIS. SIMILAR IDEAS ARE FOUND IN THE 15.00Z ECMWF ENSEMBLE. THE STABILITY AND LACK OF SPREAD WITHIN THE NUMERICAL GUIDANCE FOR THIS WEATHER SYSTEM ARE VERY HIGH. ONE ISSUE THAT MAY PRECLUDE THIS FROM BEING A MORE SIGNIFICANT EVENT IS THAT THE BOTH THE UPPER LEVEL AND SURFACE WAVES APPEAR TO BE WEAKENING AS IT APPROACHES THE UPPER MIDWEST. 500 MB STANDARDIZED ANOMALIES DROP FROM -2.5 ACROSS KANSAS TO BARELY BELOW NORMAL AS IT CROSSES THE AREA. THIS IS REFLECTED IN THE SURFACE LOW PRESSURE WHICH REMAINS AROUND 1000 MB THROUGHOUT. EARLIER RUNS SHOWED DEEPER CYCLOGENESIS WITH 980-990 MB LOWS. THE 15.12Z ECMWF REALLY DAMPENS OUT THE UPPER LEVEL AND SURFACE WAVE...BECOMING ALMOST OCCLUDED BY FRIDAY AFTERNOON. TEMPERATURE PROFILES ACROSS THE AREA CONTINUE TO SHOW AN ALL SNOW EVENT...THOUGH THERE IS A SLIGHT WARMING TREND NOTED. IF THE SYSTEM WERE TO DEEPEN AND WRAP UP MORE...THEN A PUSH OF WARMER AIR COULD PRESENT A RAIN/SNOW MIX BUT RIGHT NOW THIS IS NOT THE CASE. HAVE TRENDED PRECIPITATION CHANCES ABOVE MODEL CONSENSUS THURSDAY NIGHT GIVEN CONTINUED EXCELLENT MODEL AGREEMENT AND THE SLOWER TIMING OF THE SYSTEM. ALTHOUGH IT IS A BIT TOO EARLY TO SPECULATE ON AMOUNTS...25.12Z GFS ENSEMBLE AND 25.12Z ECMWF SHOW WIDESPREAD AMOUNTS OF 0.50 TO 0.75 INCHES OF LIQUID. SNOW RATIOS ARE NOT VERY HIGH...MOST LIKELY A BIT BELOW CLIMATOLOGICAL VALUES /10 TO 12:1/ SO IN SHORT...WARNING LEVEL /6 INCHES/ SNOW TOTALS COULD BE MET OR EXCEEDED ACROSS PARTS OF THE REGION. && .AVIATION...TONIGHT AND SATURDAY 532 PM CST FRI FEB 15 2013 DESPITE THE CLEAR SKIES TO BEGIN THE AVIATION FORECAST...THE FORECAST IS QUITE DIFFICULT. THE PROBLEM IS TRYING TO FIGURE OUT IF AND WHEN STRATUS WOULD MOVE INTO THE TAF SITES FROM THE NORTHWEST. PRESENTLY THERE ARE AREAS OF MVFR STRATUS OVER THE EASTERN DAKOTAS AND MOSTLY VFR STRATUS ACROSS NORTHERN MINNESOTA. WITH A NORTHWEST FLOW AND NOW HEADING INTO THE NIGHTTIME COOLING PERIOD...IT SHOULD BE EASIER FOR THE STRATUS TO FLOW TOWARDS THE TAF SITES. MODELS SUCH AS THE RAP THAT HAVE A BETTER HANDLE ON THE CURRENT LOW LEVEL MOISTURE SITUATION PROG THESE CLOUDS TO MOVE INTO THE TAF SITES AROUND 09Z...A LITTLE LATER THAN PREVIOUSLY FORECAST. MVFR CEILINGS STILL SEEM THE WAY TO GO. THERE CERTAINLY COULD BE SOME FLURRIES WITH THIS STRATUS...BUT LACK THEREOF UPSTREAM ALONG WITH CONFIDENCE OF THE STRATUS IMPACTING THE TAF SITES BEING LESS THAN AVERAGE HAS RESULTED IN REMOVAL OF FLURRIES. IF THE STRATUS DOES INDEED MOVE INTO THE TAF SITES...NEXT QUESTION WOULD BE WHEN DOES IT CLEAR. WITH A SURFACE RIDGE OVER THE EASTERN DAKOTAS MOVING OVERHEAD ON SATURDAY...THE LIGHTER WINDS ASSOCIATED WITH IT MAKE MIXING A LITTLE MORE DIFFICULT. HOWEVER...THE HIGHER SUN ANGLE NOW SHOULD ALLOW THE CLOUDS TO SCATTER OUT BY 20Z. NEEDLESS TO SAY...A LOW CONFIDENCE FORECAST WITH WHETHER CONDITIONS CAN STAY VFR OR END UP WITH MVFR CEILINGS. && .ARX WATCHES/WARNINGS/ADVISORIES... 319 PM CST FRI FEB 15 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BAUMGARDT LONG TERM...TAYLOR/BAUMGARDT AVIATION...AJ
AREA FORECAST DISCUSSION...CORRECTED
NWS MILWAUKEE/SULLIVAN WI
353 PM CST THU FEB 14 2013 .SHORT TERM... .TONIGHT AND FRIDAY...FORECAST CONFIDENCE MEDIUM. SURFACE LOW MOVES NORTHEAST FROM LAKE HURON TO SOUTHERN QUEBEC AS HIGH PRESSURE BUILDS INTO THE NORTHERN AND CENTRAL PLAINS. DECENT SHORTWAVE MOVING BY JUST TO OUR SOUTHWEST EARLY THIS EVENING. HOWEVER...APPEARS PRECIP...OTHER THAN FLURRIES...WILL STICK TO OUR SOUTHWEST. MODELS AGREE ON KEEPING MAIN AREA OF PRECIP TO THE SOUTHWEST. ALSO...EXTRAPOLATION OF CURRENT SWATH OF LIGHT SNOW ASSOCIATED WITH VORT MAX OVER CENTRAL IOWA WOULD SHOW MAIN AREA OF PRECIP MOVING TO OUR SOUTHWEST. LIGHT SNOW/FLURRIES WRAPPING AROUND THE LOW IN EAST CENTRAL WISCONSIN WILL EXIT THIS EVENING AS THE LOW LIFTS NORTHEAST. HOWEVER...KEPT FLURRY MENTION IN FOR THE NIGHT UNTIL DRY AIR CURRENTLY IN MINNESOTA MOVES IN. THE CLEARING AREA IN MINNESOTA HAS EXPANDED...AND MATCHES UP WELL WITH THE RAP 850MB RH. WOULD HAVE THIS GETTING TO OUR WEST/NORTHWEST AREA SOMETIME AROUND MIDNIGHT...PUTTING A HALT TO FLURRIES AS IT MOVES IN. THIS COULD CREATE A PROBLEM FOR TONIGHT/S LOWS...COULD SEE TEMPS REALLY DROP IF SIGNIFICANT CLEARING TAKES PLACE. A WEAKER SHORTWAVE MOVES THROUGH TOMORROW AFTERNOON...SO EXPECTING CLOUD COVER TO INCREASE FRIDAY MORNING WITH FLURRIES RETURNING. THERE IS SOME PVA AND WAA BETWEEN 850 AND 700MB IN THE AFTERNOON...BUT OVERALL NOT IMPRESSED BY Q VECTOR CONVERGENCE. 925MB COLD AIR ADVECTION TAKES HOLD TONIGHT. 925MB TEMPS DROP FROM AROUND -3 TO -5C AT 00Z FRIDAY TO -11 TO -13C BY 12Z FRIDAY. NOT TOO MUCH OF A REBOUND FOR FRIDAY EITHER. HIGHEST 925MB TEMPS ON FRIDAY ABOUT -10 TO -12C. HOWEVER...MODELS HAVE BEEN A BIT COOL WHERE SNOW PACK ISN/T AS SIGNIFICANT. PUT IN HIGHS IN THE 22-27F RANGE. SATURDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH SOUTHERN WISCONSIN IS ON THE WESTERN PERIPHERY OF THE LARGE UPPER TROUGH AXIS. MODELS SHOW SHEARED CYCLONIC VORTICITY AXIS MOVING ACROSS SOUTHERN WISCONSIN. SATURATED LOW LEVELS BELOW AN INVERSION AROUND 5 THSD FT WITH STEEP LAPSE RATES BELOW THE INVERSION. SOME FLURRY POTENTIAL. SURFACE RIDGE AXIS THEN NUDGES INTO WESTERN WISCONSIN BY THE END OF THE DAY. SATURDAY NIGHT THROUGH SUNDAY NIGHT...FORECAST CONFIDENCE...MEDIUM TO HIGH THE HIGH PRESSURE RIDGE SHIFTS EAST OF AREA WITH THE PLAINS TROUGH APPROACHING. WARM ADVECTION UNDERWAY THROUGH THIS PERIOD. WARMEST 925 TEMPS ARRIVE SUNDAY NIGHT WITH READINGS RISING TO AT OR ABOVE 0 CELSIUS. SHOULD BE A NON DIURNAL TEMPERATURE TREND WITH RISING TEMPERATURES. MONDAY AND MONDAY NIGHT FORECAST CONFIDENCE...MEDIUM TO HIGH THE MID/UPPER LEVEL UPPER TROUGH EXITS THE NORTHERN AND CENTRAL PLAINS MONDAY AND MOVES INTO THE WESTERN GREAT LAKES MONDAY NIGHT. A DECENT SURGE OF MOISTURE ADVECTS NORTHWARD AHEAD AND ALONG OF THE LOWER LEVEL TROUGH. GFS/GEM AND ECMWF ALL SHOW PRECIP ARRIVING MONDAY AFTERNOON AND MONDAY NIGHT. THICKNESS AND 850 MB TEMPERATURES TREND TOWARD A MIX OR MAINLY SNOW EXCEPT FAR SOUTHEAST. HOWEVER GFS FORECAST SOUNDING SHOW A WARM BOUNDARY LAYER WHICH WOULD BRING MORE RAIN SOUTH AND RAIN/SNOW NORTH. 850/925 TEMPS THEN COLLAPSE DURING THE EVENING TRANSITIONING THE PRECIPITATION TO SNOW. .LONG TERM... TUESDAY...FORECAST CONFIDENCE...MEDIUM LINGERING CYCLONIC FLOW FROM THE DEPARTING MID LEVEL TROUGH SUGGESTS KEEPING SOME SMALL POPS EAST FOR SNOW SHOWERS EARLY. THEN PRONOUNCED DRYING. DECENT COLD ADVECTION EXPECTED BEHIND THE STRENGTHENING LOW TO THE EAST/NORTHEAST. WEDNESDAY...FORECAST CONFIDENCE... BROAD CYCLONIC FLOW MOVES OFF AS A MID LEVEL RIDGE MOVES ACROSS WISCONSIN. A RATHER STRONG CANADIAN HIGH WILL BE RIDGING SOUTHEAST INTO THE AREA CONTINUING THE COLD TEMPERATURES. THURSDAY...FORECAST CONFIDENCE... STRONG SHORTWAVE OVER THE SOUTHWEST U.S. LIFTS NORTHEAST. MAIN DIFFERENCE IS THAT THE 12Z ECMWF IS SOMEWHAT SLOWER AND FARTHER SOUTH. GFS AND ECMWF BOTH BRING A STRONG LOW THAT WOULD FAVOR HEAVY SNOW EVENTUALLY AFFECTING PORTIONS OF THE FORECAST AREA. THE ECMWF IS A FAVORABLE TRACK FOR HEAVY SNOW OVER SOUTHEAST WISCONSIN...WITH THE GFS A LITTLE FARTHER NORTH. HEAVY PRECIPITATION AMOUNTS ON BOTH MODELS...WITH THE HEAVIEST ON THE GFS. THIS WILL BE A POTENTIAL SNOWSTORM FOR LATER THURSDAY OR FRIDAY. PREFER THE SOMEWHAT SLOWER ECMWF SO WILL NOT RAISE POPS FROM THE CONSENSUS GRIDS ON THURSDAY. && .AVIATION/00Z TAFS/... VFR CEILINGS WERE WEST OF ABOUT A JANESVILLE TO GREEN LAKE LINE AROUND MID AFTERNOON. THINKING THESE CONDITIONS WILL SPREAD EAST THIS EVENING AS THE SURFACE LOW MOVES EAST. NAM AND GFS SOUNDINGS QUITE DIFFERENT IN TERMS OF CEILING HEIGHT. THINKING THE SOLUTION IS SOMEWHERE IN THE MIDDLE BASED ON UPSTREAM OBS. LEANING TOWARDS VFR CONDITIONS FOR THE MAJORITY OF THE NIGHT ONCE THE LOW MOVES EAST. AREA OF DRY AIR OVER MINNESOTA HAS EXPANDED AND WILL LIKELY ARRIVE IN OUR AREA AFTER MIDNIGHT. MORE CONFIDENT IN VFR CONDITIONS THEN. COULD SEE SCATTERED FLURRIES TONIGHT UNTIL DRY AIR OVER MINNESOTA MOVES IN. NOT EXPECTING ANY ACCUMULATION AT THE TAF SITES THOUGH. CLOUDS WILL BUILD BACK IN FRIDAY MORNING AS ANOTHER SHORTWAVE APPROACHES. THIS WILL BRING ANOTHER CHANCE FOR FLURRIES AS WELL. NOT EXPECTING MUCH IF ANY ACCUMULATION. && .MARINE... A SMALL CRAFT ADVISORY IS IN EFFECT THROUGH MIDNIGHT TONIGHT AS LOW PRESSURE MOVES OFF TO THE NORTHEAST. SOUNDINGS SHOW WIND GUSTS DIMINISHING AFTER MIDNIGHT. HOWEVER...THE PRESSURE GRADIENT IS STILL FAIRLY TIGHT THROUGH FRIDAY MORNING AND THERE COULD BE A FEW GUSTS TO CRITERIA AFTER MIDNIGHT. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR LMZ643>646. && $$ TONIGHT/FRIDAY AND AVIATION/MARINE...MEB FRIDAY NIGHT THROUGH THURSDAY...HENTZ
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
306 PM CST THU FEB 14 2013 .SHORT TERM... .TONIGHT AND FRIDAY...FORECAST CONFIDENCE MEDIUM. SURFACE LOW MOVES NORTHEAST FROM LAKE HURON TO SOUTHERN QUEBEC AS HIGH PRESSURE BUILDS INTO THE NORTHERN AND CENTRAL PLAINS. DECENT SHORTWAVE MOVING BY JUST TO OUR SOUTHWEST EARLY THIS EVENING. HOWEVER...APPEARS PRECIP...OTHER THAN FLURRIES...WILL STICK TO OUR SOUTHWEST. MODELS AGREE ON KEEPING MAIN AREA OF PRECIP TO THE SOUTHWEST. ALSO...EXTRAPOLATION OF CURRENT SWATH OF LIGHT SNOW ASSOCIATED WITH VORT MAX OVER CENTRAL IOWA WOULD SHOW MAIN AREA OF PRECIP MOVING TO OUR SOUTHWEST. LIGHT SNOW/FLURRIES WRAPPING AROUND THE LOW IN EAST CENTRAL WISCONSIN WILL EXIT THIS EVENING AS THE LOW LIFTS NORTHEAST. HOWEVER...KEPT FLURRY MENTION IN FOR THE NIGHT UNTIL DRY AIR CURRENTLY IN MINNESOTA MOVES IN. THE CLEARING AREA IN MINNESOTA HAS EXPANDED...AND MATCHES UP WELL WITH THE RAP 850MB RH. WOULD HAVE THIS GETTING TO OUR WEST/NORTHWEST AREA SOMETIME AROUND MIDNIGHT...PUTTING A HALT TO FLURRIES AS IT MOVES IN. THIS COULD CREATE A PROBLEM FOR TONIGHT/S LOWS...COULD SEE TEMPS REALLY DROP IF SIGNIFICANT CLEARING TAKES PLACE. A WEAKER SHORTWAVE MOVES THROUGH TOMORROW AFTERNOON...SO EXPECTING CLOUD COVER TO INCREASE FRIDAY MORNING WITH FLURRIES RETURNING. THERE IS SOME PVA AND WAA BETWEEN 850 AND 700MB IN THE AFTERNOON...BUT OVERALL NOT IMPRESSED BY Q VECTOR CONVERGENCE. 925MB COLD AIR ADVECTION TAKES HOLD TONIGHT. 925MB TEMPS DROP FROM AROUND -3 TO -5C AT 00Z FRIDAY TO -11 TO -13C BY 12Z FRIDAY. NOT TOO MUCH OF A REBOUND FOR FRIDAY EITHER. HIGHEST 925MB TEMPS ON FRIDAY ABOUT -10 TO -12C. HOWEVER...MODELS HAVE BEEN A BIT COOL WHERE SNOW PACK ISN/T AS SIGNIFICANT. PUT IN HIGHS IN THE 22-27F RANGE. SATURDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH SOUTHERN WISCONSIN IS ON THE WESTERN PERIPHERY OF THE LARGE UPPER TROUGH AXIS. MODELS SHOW SHEARED CYCLONIC VORTICITY AXIS MOVING ACROSS SOUTHERN WISCONSIN. SATURATED LOW LEVELS BELOW AN INVERSION AROUND 5 THSD FT WITH STEEP LAPSE RATES BELOW THE INVERSION. SOME FLURRY POTENTIAL. SURFACE RIDGE AXIS THEN NUDGES INTO WESTERN WISCONSIN BY THE END OF THE DAY. SATURDAY NIGHT THROUGH SUNDAY NIGHT...FORECAST CONFIDENCE...MEDIUM TO HIGH THE HIGH PRESSURE RIDGE SHIFTS EAST OF AREA WITH THE PLAINS TROUGH APPROACHING. WARM ADVECTION UNDERWAY THROUGH THIS PERIOD. WARMEST 925 TEMPS ARRIVE SUNDAY NIGHT WITH READINGS RISING TO AT OR ABOVE 0 CELSIUS. SHOULD BE A NON DIURNAL TEMPERATURE TREND WITH RISING TEMPERATURES. MONDAY AND MONDAY NIGHT FORECAST CONFIDENCE...MEDIUM TO HIGH THE MID/UPPER LEVEL UPPER TROUGH EXITS THE NORTHERN AND CENTRAL PLAINS MONDAY AND MOVES INTO THE WESTERN GREAT LAKES MONDAY NIGHT. A DECENT SURGE OF MOISTURE ADVECTS NORTHWARD AHEAD AND ALONG OF THE LOWER LEVEL TROUGH. GFS/GEM AND ECMWF ALL SHOW PRECIP ARRIVING MONDAY AFTERNOON AND MONDAY NIGHT. THICKNESS AND 850 MB TEMPERATURES TREND TOWARD A MIX OR MAINLY SNOW EXCEPT FAR SOUTHEAST. HOWEVER GFS FORECAST SOUNDING SHOW A WARM BOUNDARY LAYER WHICH WOULD BRING MORE RAIN SOUTH AND RAIN/SNOW NORTH. 850/925 TEMPS THEN COLLAPSE DURING THE EVENING TRANSITIONING THE PRECIPITATION TO SNOW. .LONG TERM... TUESDAY...FORECAST CONFIDENCE...MEDIUM LINGERING CYCLONIC FLOW FROM THE DEPARTING MID LEVEL TROUGH SUGGESTS KEEPING SOME SMALL POPS EAST FOR SNOW SHOWERS EARLY. THEN PRONOUNCED DRYING. DECENT COLD ADVECTION EXPECTED BEHIND THE STRENGTHENING LOW TO THE EAST/NORTHEAST. WEDNESDAY...FORECAST CONFIDENCE... BROAD CYCLONIC FLOW MOVES OFF AS A MID LEVEL RIDGE MOVES ACROSS WISCONSIN. A RATHER STRONG CANADIAN HIGH WILL BE RIDGING SOUTHEAST INTO THE AREA CONTINUING THE COLD TEMPERATURES. THURSDAY...FORECAST CONFIDENCE... STRONG SHORTWAVE OVER THE SOUTHWEST U.S. LIFTS NORTHEAST. MAIN DIFFERENCE IS THAT THE 12Z ECMWF IS SOMEWHAT SLOWER AND FARTHER SOUTH. GFS AND ECMWF BOTH BRING A STRONG LOW THAT WOULD FAVOR HEAVY SNOW EVENTUALLY AFFECTING PORTIONS OF THE FORECAST AREA. THE ECMWF IS A FAVORABLE TRACK FOR HEAVY SNOW OVER SOUTHEAST WISCONSIN...WITH THE GFS A LITTLE FARTHER NORTH. HEAVY PRECIPITATION AMOUNTS ON BOTH MODELS...WITH THE HEAVIEST ON THE GFS. THIS WILL BE A POTENTIAL SNOWSTORM FOR LATER THURSDAY OR FRIDAY. PREFER THE SOMEWHAT SLOWER ECMWF SO WILL NOT RAISE POPS FROM THE CONSENSUS GRIDS ON THURSDAY. && .AVIATION/00Z TAFS/... VFR CEILINGS WERE WEST OF ABOUT A JANESVILLE TO GREEN LAKE LINE AROUND MID AFTERNOON. THINKING THESE CONDITIONS WILL SPREAD EAST THIS EVENING AS THE SURFACE LOW MOVES EAST. NAM AND GFS SOUNDINGS QUITE DIFFERENT IN TERMS OF CEILING HEIGHT. THINKING THE SOLUTION IS SOMEWHERE IN THE MIDDLE BASED ON UPSTREAM OBS. LEANING TOWARDS VFR CONDITIONS FOR THE MAJORITY OF THE NIGHT ONCE THE LOW MOVES EAST. AREA OF DRY AIR OVER MINNESOTA HAS EXPANDED AND WILL LIKELY ARRIVE IN OUR AREA AFTER MIDNIGHT. MORE CONFIDENT IN VFR CONDITIONS THEN. COULD SEE SCATTERED FLURRIES TONIGHT UNTIL DRY AIR OVER MINNESOTA MOVES IN. NOT EXPECTING ANY ACCUMULATION AT THE TAF SITES THOUGH. CLOUDS WILL BUILD BACK IN FRIDAY MORNING AS ANOTHER SHORTWAVE APPROACHES. THIS WILL BRING ANOTHER CHANCE FOR FLURRIES AS WELL. NOT EXPECTING MUCH IF ANY ACCUMULATION. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR LMZ643>646. && $$ TONIGHT/FRIDAY AND AVIATION/MARINE...MEB FRIDAY NIGHT THROUGH THURSDAY...HENTZ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
237 PM CST THU FEB 14 2013 .SHORT TERM...TONIGHT THROUGH SUNDAY 237 PM CST THU FEB 14 2013 MAIN FORECAST CONCERNS FOR THE SHORT TERM PERIOD: 1. TEMPERATURE AND CLOUD TRENDS THROUGHOUT CURRENTLY AS OF 20Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED RIDGING JUST OFF THE WEST COAST OF THE U.S. INTO BRITISH COLUMBIA...WHILE TROUGHING COVERED MUCH OF EASTERN CANADA INTO THE NORTHERN PLAINS AND WESTERN GREAT LAKES REGION. COMING THROUGH THE TROUGH WAS A SHORTWAVE TROUGH APPROACHING THE SIOUX FALLS SOUTH DAKOTA AREA...WHILE ANOTHER SHORTWAVE WAS SEEN IN CENTRAL SASKATCHEWAN. THE SHORTWAVE THAT AFFECTED THE AREA LAST NIGHT INTO THIS MORNING HAS MOVED OFF INTO LOWER MICHIGAN. RADAR IMAGERY SHOWED A FEW RAIN/SNOW SHOWERS OVER MUCH OF WISCONSIN IN THE WAKE OF THE LOWER MICHIGAN SHORTWAVE...DUE TO CYCLONIC FLOW OF LOW LEVEL MOISTURE AND STEEP LOW LEVEL LAPSE RATES. TO THE WEST...RADAR ALSO SHOWS A BAND OF RAIN/SNOW FROM CENTRAL SOUTH DAKOTA INTO NORTHWEST IOWA...ASSOCIATED WITH THE SIOUX FALLS SHORTWAVE. NORTHWEST LOW LEVEL WINDS BETWEEN THE TWO SHORTWAVES ARE GRADUALLY BRINGING IN COLDER AIR. SOUNDINGS AT BIS...ABR...MPX AND INL ALL HAD 850MB TEMPS DROP 3-4C BETWEEN 00Z AND 12Z...ALL BETWEEN -7 AND -12C AS OF 12Z. SOME DRIER AIR WAS ALSO ACCOMPANYING THE NORTHWEST WINDS...NOTED BY SATELLITE IMAGERY SHOWING CLEARING ACROSS NORTHERN MN. TONIGHT THROUGH SATURDAY DEFINITELY ARE GOING TO BE COLDER THAN AS OF LATE. THE SHORTWAVE OVER CENTRAL SASKATCHEWAN COMBINED WITH ANOTHER SHORTWAVE CURRENTLY UP IN NORTHERN MANITOBA ARE GOING TO DIG SOUTH...CARVING OUT A DEEP TROUGH OVER THE REGION BY 00Z SATURDAY. 850MB TEMPS FALL AS THIS TROUGH FORMS...DROPPING TO -14 TO -18C BY 18Z FRIDAY AND -16 TO -20C BY 12Z SATURDAY PER MODEL CONSENSUS. THOSE AT 12Z SATURDAY ARE 1.5 STANDARD DEVIATIONS BELOW NORMAL. THE ONLY MITIGATING FACTOR TO THE COLD AIR WOULD BE THE LACK OF SNOW OVER THE SOUTHWEST HALF OF THE FORECAST AREA...WHICH IF SOME SUN CAN OCCUR WOULD REALLY HELP TO BOOST TEMPS UP GIVEN THE CLIMBING SUN ANGLE NOW. GENERALLY FOLLOWED A BLEND OF THE ECMWF AND 30 DAY BIAS CORRECTED GFS GRIDDED MOS GUIDANCE DATA SINCE THEY HAVE BEEN DOING WELL AS OF LATE FOR HIGHS. LOWS ARE HIGHLY CONTINGENT ON CLOUD COVER. AFTER SOME CLEARING TONIGHT... MORE LOW TO MID CLOUDS MOVE IN FROM THE NORTHWEST FOR FRIDAY AND FRIDAY NIGHT...ASSOCIATED WITH THAT SHORTWAVE DROPPING DOWN OUT OF MANITOBA. THESE CLOUDS COMBINED WITH A NORTHWEST BREEZE SHOULD HELP KEEP LOWS FROM BOTTOMING OUT...THUS A BLEND OF GUIDANCE FOR LOWS SEEMS REASONABLE. HANDLING CLOUD COVER SATURDAY COULD BE TRICKY. A RIDGE OF HIGH PRESSURE IS PROGGED TO BUILD INTO THE WESTERN PORTIONS OF THE FORECAST AREA. WILL FOLLOW THE GENERAL MODEL CONSENSUS OF THE LOW CLOUDS BREAKING UP THROUGH THE DAY...DUE TO A COMBINATION OF THE LOW LEVEL FLOW BECOMING ANTICYCLONIC AND DAYTIME MIXING. HOWEVER...IT IS POSSIBLE THE CLOUDS COULD HANG ON FOR MUCH OF THE DAY. THIS COMBINED WITH 850MB TEMPS STILL ONLY BETWEEN -14C WEST TO -20C EAST AT 18Z WILL KEEP TEMPERATURES SEASONABLY COOL. FOR SATURDAY NIGHT AND SUNDAY...A POTENT SHORTWAVE TROUGH IS PROGGED TO DROP INTO THE PACIFIC NORTHWEST AND NORTHERN ROCKIES...FORMING TWO DISTINCT LOW PRESSURE AREAS ACROSS THE PLAINS DURING THE DAY SUNDAY. A SOUTHERLY LOW LEVEL JET WILL DEVELOP AHEAD OF THESE TWO LOWS...BRINGING UP WARMER AIR. AN INCREASE OF MID AND HIGH CLOUDS ARE LIKELY TO ACCOMPANY THIS WARM ADVECTION. SO THE QUESTION FOR LOWS SATURDAY NIGHT IS TIMING OF WHEN THE WARM ADVECTION STARTS UP AND MID CLOUDS MOVE IN...VERSUS THE DEPARTURE TO THE EAST OF THE SURFACE RIDGE. OUR WISCONSIN COUNTIES HAVE THE BEST SHOT OF FAVORABLE RADIATIONAL COOLING CONDITIONS...THUS LEANED TOWARDS THE COLDER SIDE OF GUIDANCE THERE. TEMPERATURES SHOULD RISE FROM LATE SATURDAY NIGHT THROUGH SUNDAY AT MOST LOCATIONS AS SOUTHERLY WINDS INCREASE. QUESTION ON SUNDAY IS HOW WARM DO WE GET...WITH 850MB TEMPS THAT COULD APPROACH 0C NEAR CHARLES CITY IA BY 00Z MONDAY. IT APPEARS SUNSHINE WILL BE ON THE INCREASE WEST OF THE MS RIVER AS THE MID CLOUD LIFTS TO THE NORTH. GIVEN THE LACK OF SNOW OVER THE SOUTHWEST HALF OF THE FORECAST AREA...LEANED MORE TOWARDS THE CONSISTENTLY WARM ECMWF...BRINGING HIGHS AT LEAST TO THE MID 30S AROUND CHARLES CITY. PRECIPITATION WISE...MUCH OF THE SHORT TERM LOOKS DRY WITH RESPECT TO REACHING 0.01" OF LIQUID EQUIVALENT IN ANY 12 HOUR PERIOD. FLURRIES LOOK LIKELY...HOWEVER...FOR FRIDAY AND FRIDAY NIGHT OUT OF THOSE LOW CLOUDS SINCE THEY EXIST WITHIN THE DENDRITIC GROWTH ZONE AND HAVE WEAK LIFT FROM THE SHORTWAVE. PREVIOUS FORECAST MENTIONED CONCERN THAT AS THE WARM ADVECTION STARTS UP SATURDAY NIGHT THAT WE COULD SEE SOME SNOW FALL OUT OF THE ASSOCIATED MID CLOUD DECK. THAT STILL REMAINS A CONCERN...THOUGH THINK FLURRIES WOULD BE THE MOST THAT GETS PRODUCED. THEN AGAIN...THESE FLURRIES MIGHT BE ABSORBED BY LOWER LEVEL DRY AIR. FOR NOW HAVE KEPT THE FORECAST DRY FOR SATURDAY NIGHT AND SUNDAY. .LONG TERM...SUNDAY NIGHT THROUGH THURSDAY 237 PM CST THU FEB 14 2013 MAIN CONCERNS FOR THE LONG TERM PERIOD... 1. TEMPERATURES AND PRECIPITATION POTENTIAL THROUGH MONDAY 2. BRIEF ARCTIC AIR SHOT FOR MID-WEEK 3. POTENTIAL FOR A WINTER STORM TO IMPACT THE AREA LATE IN THE WEEK VERY GOOD MODEL AGREEMENT EXISTS AMONGST THE 14.12Z ECMWF/GFS/CANADIAN/UKMET THROUGHOUT MUCH OF THE LONG TERM PERIOD. FOR SUNDAY NIGHT INTO MONDAY...THE TROUGHING THAT WAS COMING ACROSS THE NORTHERN ROCKIES EVOLVES BY MONDAY EVENING INTO A FULL LONGITUDINAL TROUGH ACROSS THE CANADIAN AND U.S. PLAINS. THIS TROUGHING EVENTUALLY PHASES TOGETHER AS IT CROSSES THE REGION AND HEADS INTO THE GREAT LAKES FOR TUESDAY. PRIOR TO THE PHASING...A REALLY STRONG PUSH OF WARM AIR COMES UP AT THE REGION WITH 850MB TEMPS BETWEEN -2C AND +4C AT 12Z MONDAY. HAVE BOOSTED HIGH TEMPERATURES FOR MONDAY AS A RESULT...THOUGH COULD BE EVEN HIGHER AS NOTED BY THE 14.12Z ECMWF. ALSO...MODELS CONTINUE TO TREND FARTHER WEST WITH THE SOUTHERN LOW COMING OUT OF THE SOUTHERN PLAINS. AS SUCH...NOW ABOUT THE EASTERN TWO THIRDS OF THE AREA IS AFFECTED BY LIGHT PRECIPITATION FOR MONDAY AFTERNOON AND EVENING. THUS...HAVE EXPANDED LOW PRECIPITATION CHANCES FARTHER WEST AND RAISED THEM 5-10 PERCENT. IF TRENDS CONTINUE...THESE CHANCES WILL NEED TO BE RAISED MORE. WITH THE WARMER TEMPERATURES TOO...MIXING WITH OR CHANGING TO RAIN IS AN ISSUE AS WELL. AS THE PHASED TROUGH FORMS OVER THE AREA MONDAY NIGHT AND TUESDAY... ARCTIC AIR FLOWS INTO THE REGION. 850MB TEMPS PLUMMET TO -12 TO -14C BY 12Z TUESDAY AND -14 TO -20C BY 12Z WEDNESDAY. THUS...A MUCH COOLER PERIOD IS ON TAP AGAIN. CANADIAN HIGH PRESSURE BUILDING DOWN INTO THE NORTHERN PLAINS...IN THE WAKE OF THE PHASED TROUGH...WILL PROVIDE FOR BLUSTERY CONDITIONS. WIND CHILLS RIGHT NOW LOOK TO STAY JUST ABOVE ADVISORY CRITERIA...BOTTOMING OUT AT MOST IN THE -15 TO -20F RANGE WEDNESDAY MORNING. LASTLY...ABOUT THE POTENTIAL WINTER STORM LATE IN THE WEEK. THERE IS SURPRISINGLY CONSISTENT AND GOOD MODEL AGREEMENT AMONGST THE ECMWF...GFS AND THEIR RESPECTIVE ENSEMBLES OF A DEEP TROUGH FORMING OVER THE WESTERN U.S. ON WEDNESDAY. AS THIS TROUGH HEADS EAST TOWARDS THE PLAINS...A DEEP LOW PRESSURE AREA DEVELOPS OVER THE CENTRAL PLAINS BY THURSDAY MORNING. THERE ARE A FEW QUESTIONS FROM HERE ON...WHICH MAY TAKE AT LEAST A FEW MORE DAYS TO ANSWER: 1. TIMING AND STRENGTH AS USUAL 2. HOW QUICK DOES THE PRECIPITATION SPREAD INTO THE AREA IF IT INDEED AFFECTS US 3. HOW MUCH PRECIPITATION WOULD OCCUR 4. DEPENDING ON HOW MUCH THE SYSTEM WRAPS UP...MAY HAVE TO DEAL WITH PRECIPITATION TYPE ISSUES FOR NOW HAVE STAYED WITH A CONSENSUS APPROACH...WHICH BY THURSDAY NIGHT YIELDS 50-60 PERCENT CHANCES OF PRECIPITATION REGION-WIDE. ALL PRECIPITATION RIGHT NOW LOOKS TO FALL AS SNOW...WHICH COULD BE SIGNIFICANT. SINCE THE STORM IS VERY FAR OUT IN THE FORECAST AND JUST BEYOND THE CURRENT HWO PERIOD...HAVE KEPT THE MENTION OF THE STORM TO THIS DISCUSSION ONLY. HOWEVER...IF TRENDS ON THIS SYSTEM CONTINUE...LATER SHIFTS WILL NEED TO MENTION THE STORM IN THE HWO AND IN OTHER DECISION SUPPORT SERVICES. && .AVIATION...THROUGH 18Z FRIDAY 1210 PM CST THU FEB 14 2013 WHILE VISIBILITIES NOT EXPECTED TO HAMPER AVIATION...CEILINGS WILL BE TROUBLESOME WITH ONE SHORT WAVE TROUGH PASSING BY TO THE SOUTHWEST AND A MIX OF STRATUS AND MID LEVEL CLOUDS UPSTREAM. COMBINATION OF PASSING SHORT WAVE AND CYCLONIC FLOW FROM PREVIOUS SYSTEM...CLOUDS WILL FILL IN QUITE A BIT REST OF TODAY WITH GENERAL VFR AND LIMITED MVFR CEILINGS ANTICIPATED. COULD ALSO SEE SOME SNOW SHOWERS BUT AGAIN...DO NOT EXPECT BIG IMPACT THERE. SUBSIDENCE TO THE NORTH SHOULD PRODUCE PERIOD TONIGHT OF CLEAR TO SCATTERED DECKS BEFORE MAINLY MID LEVEL CLOUDS ADVECT BACK IN EARLY FRIDAY. STEEP LAPSE RATES SUGGEST STRATUS AND FLURRIES COULD DOMINATE ON FRIDAY AS WELL BUT MAINLY VFR CONDITIONS SHOULD PREVAIL. && .ARX WATCHES/WARNINGS/ADVISORIES... 237 PM CST THU FEB 14 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION.....SHEA
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1126 PM CST WED FEB 13 2013 .SHORT TERM...TONIGHT INTO THURSDAY 827 PM CST WED FEB 13 2013 827 PM BRIEF UPDATE...14.00Z NAM SHIFTED THE NARROW FRONTOGENESIS BAND ON THE NORTH SIDE OF THE SURFACE LOW SLIGHTLY SOUTH... IMPACTING MOSTLY CLARK NOW. 14.23Z HRRR ALSO HAS A VERY SLIGHT TREND SOUTH. GIVEN THE UNCERTAINTY ON WHERE EXACTLY THIS BAND WILL SET UP...HAVE DECLINED TO UPGRADE TO A WARNING. IN GENERAL...SNOW AMOUNTS SHOULD TOTAL IN THE 3-6 INCH RANGE...HIGHEST MOST LIKELY OCCURRING IN NORTHERN CLARK COUNTY. DEFINITELY HEAVIEST SNOW BETWEEN MIDNIGHT AND 8 AM REMAINS ON TARGET. 724 PM BRIEF UPDATE...IN ADDITION TO THE UPDATE INFORMATION BELOW MADE AT 555 PM...NOTICED THAT BLENDING THE QPF FOR 06-12Z THURSDAY FROM THE PREFERRED MODEL GROUP RESULTS IN A NARROW BAND AROUND HIGHWAY 29 INTO SOUTHERN TAYLOR COUNTY UPWARDS OF 0.30 INCHES. SNOW TO WATER RATIOS...GIVEN ONLY A 75 MB DEEP DENDRITIC GROWTH ZONE PROGGED...SHOULD END UP MOSTLY IN THAT 13-15 TO 1 RANGE... RESULTING IN A 6 HOUR PERIOD OF 3-5 INCHES OF SNOW. WE COULD APPROACH LOW END WARNING CRITERIA IN THIS BAND. AFTER COLLABORATION WITH GRB...WILL STICK WITH THE ADVISORY FOR NOW PENDING THE 14.00Z NAM. TOUGHEST PART WITH A WARNING WOULD BE GRABBING THE RIGHT AREA SINCE THIS WILL BE A NARROW BAND. MAIN UPDATE AT 555 PM... TWO SHORTWAVES ARE EVIDENT ON WATER VAPOR...ONE OVER WEST CENTRAL MINNESOTA AND THE OTHER IN SOUTHERN SASKATCHEWAN. THESE ARE BOTH DROPPING SOUTHEAST THROUGH THE NORTHWEST FLOW ALOFT. WITH THE WEST CENTRAL MINNESOTA SHORTWAVE...TWO AREAS OF RADAR RETURNS ARE PRESENT. THE FIRST ASSOCIATED WITH WARM ADVECTION EXTENDS FROM JUST WEST OF THE TWIN CITIES SOUTH INTO NORTH CENTRAL IOWA. SO FAR...OBSERVATIONS HAVE NOT SHOWN MUCH PRECIPITATION FALLING FROM THIS BAND...SUGGESTING A LOW LEVEL DRY AIR ISSUE ABSORBING THE PRECIPITATION. THE SECOND BAND ON THE OTHER HAND IS PRODUCING SNOW...WHICH STRETCHED FROM JAMESTOWN NORTH DAKOTA TO ST CLOUD MN. THIS BAND IS ASSOCIATED WITH LOW TO MID-LEVEL FRONTOGENESIS ON THE NORTH SIDE OF THE SHORTWAVE TRACK. MANY VISIBILITY REPORTS OF A 1/2 MILE TOO IN THE SNOW. 13.20Z HRRR...13.18Z NAM...13.12Z HIRES-NMM AND REGIONAL CANADIAN ALL HAVE BEEN HANDLING CURRENT RADAR TRENDS WELL WITH THE WEST CENTRAL MINNESOTA SHORTWAVE. THE IDEA IS THAT THE WARM ADVECTION BAND OF RADAR RETURNS WILL MOVE ACROSS THE SOUTHERN TWO-THIRDS OF THE FORECAST AREA BETWEEN 02-08Z...LASTING FOR A COUPLE OF HOURS AT ANY ONE LOCATION...FOLLOWED BY A DRY SLOT. GIVEN LACK OF PRECIPITATION OBSERVED UPSTREAM...AM UNCERTAIN WHETHER WE WILL SEE ANY PRECIPITATION FROM THIS BAND. HAVE TRENDED PRECIPITATION CHANCES TOWARDS THE ABOVE MODEL GROUP IDEA AND MAY HAVE TO DRY THINGS OUT MORE. IF PRECIPITATION OCCURS...IT NOW LOOKS MORE LIKE A RAIN/SNOW ISSUE GIVEN THE WARM LAYER IS AT THE SURFACE. MODELS HAD SUGGESTED A WARM LAYER RIGHT ABOVE THE SURFACE...BUT THIS SEEMS OVERDONE BECAUSE THEY ARE NOT HANDLING THE TEMPERATURES WELL ACROSS THE SLOWLY DIMINISHING SNOWPACK. AS SUCH...REMOVED THE FREEZING RAIN/SLEET POTENTIAL. THE NORTHERN BAND IS STILL ON TRACK TO IMPACT THE ADVISORY AREA AFTER 03Z. WOULD NOT BE SURPRISED TO SEE VISIBILITIES QUICKLY DROP TO 1 MILE OR LESS SEEING THE 1/2 MILE UPSTREAM. THE NORTHERN BAND IS THEN SUGGESTED TO WRAP BACKWARDS AND TRACK SOUTHEAST ACROSS MUCH OF THE FORECAST AREA BETWEEN 09-16Z...WELL TRENDED FROM THE PREVIOUS FORECAST. AM CONCERNED A LITTLE BIT ABOUT HOW MUCH QPF COULD OCCUR IN TAYLOR AND CLARK COUNTIES WHERE THE ADVISORY IS POSTED. THE 13.12Z HIRES-NMM IS ABOUT 0.10 OF AN INCH HIGHER THAN CURRENTLY FORECAST FOR 06-12Z TONIGHT...WITH THE HRRR SUGGESTING SIMILAR POTENTIAL. HAVE RAISED QPF SLIGHTLY BUT MAY NEED TO RAISE MORE. SNOWFALL AMOUNTS UP TO 5 INCHES NOW SEEM POSSIBLE...STILL BELOW WARNING CRITERIA AT THIS POINT. FOR THURSDAY...THERE LOOKS TO BE A BREAK BETWEEN THE CURRENT SHORTWAVE TRACKING THROUGH TONIGHT INTO TOMORROW MORNING AND THEN THE ONE APPROACHING FROM SOUTHERN SASKATCHEWAN. HIRES MODELS /ARW AND NMM/ TRACK THE SHORTWAVE INTO IOWA...WITH ITS LOW TO MID LEVEL FRONTOGENESIS BAND IMPACTING FAR WESTERN PORTIONS OF SOUTHEAST MINNESOTA AND INTO NORTHEAST IOWA...PRIMARILY BETWEEN 21-03Z. MAY MAKE SOME ADJUSTMENTS TO PRECIPITATION CHANCES TO ACCOUNT FOR THE TRACK OF THIS FRONTOGENESIS BAND. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY 236 PM CST WED FEB 13 2013 13.12 MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT SATURDAY NIGHT THROUGH MONDAY. UPPER LEVEL RIDGE WILL MOVE OVER THE REGION ON SUNDAY. SOUTHERLY FLOW AT THE SURFACE WILL INCREASE AHEAD OF A TROUGH RACING ACROSS THE NORTHERN ROCKIES. WILL HAVE TO KEEP A CLOSE EYE ON TEMPERATURES ON SUNDAY. THE LATEST ECMWF WARMS HIGHS INTO THE UPPER 30S TO LOWER 40S SOUTH OF INTERSTATE 90 AND THIS SEEMS REASONABLE. THE NEXT TROUGH IS EXPECTED TO MOVE ACROSS THE REGION ON MONDAY BUT THE FORECAST AREA LOOKS TO BE SPLIT BETWEEN A SOUTHERN STREAM WAVE MOVING UP THE OHIO RIVER VALLEY AND A NORTHERN STREAM WAVE MOVING ACROSS SOUTHERN ONTARIO/NORTHERN LAKE SUPERIOR. A COLD FRONT WILL MOVE ACROSS THE AREA MONDAY NIGHT INTO TUESDAY WITH COOLER AIR ARRIVING ON TUESDAY. HIGHS ARE EXPECTED TO FALL INTO THE TEENS TO LOWER 20S. COOL HIGH PRESSURE WILL REMAIN OVERHEAD INTO WEDNESDAY WITH MAINLY DRY AND QUIET WEATHER EXPECTED. && .AVIATION...THROUGH 06Z FRIDAY 1126 PM CST WED FEB 13 2013 BAND OF RAIN AND SNOW HAS MOVED THROUGH KRST AND HAS ALMOST CLEARED KLSE...ASSOCIATED WITH A WARM FRONT. LOWER MVFR CEILINGS ARE COMING IN BEHIND THIS BAND. TO THE NORTHWEST...ANOTHER AREA OF PRECIPITATION...IN THIS CASE ALL SNOW...WAS PRESENT FROM NEAR MANKATO TO THE TWIN CITIES AS OF 05Z. THIS IS RIGHT BEHIND A COLD FRONT. EXPECT THE BAND OF SNOW TO MOVE THROUGH THE TAF SITES BETWEEN 09-15Z...WITH A FEW HOURS OF IFR VISIBILITIES AND PERHAPS EVEN IFR CEILINGS OCCURRING. KLSE LOOKS TO END UP A LITTLE CLOSER TO THE HEAVIER SNOW...THUS HAVE INCLUDED A TEMPO GROUP FOR LIFR VISIBILITIES...IN AGREEMENT WITH WHAT WAS PRESENT AT MSP. SNOWFALL ACCUMULATIONS LOOK LIGHT...GENERALLY AN INCH OR LESS. MAINLY VFR VISIBILITIES...MVFR CEILINGS AND FLURRIES ARE ANTICIPATED AFTER 15 OR 16Z...AS CYCLONIC FLOW PERSISTS IN THE WAKE OF THE LOW PRESSURE SYSTEM BRINGING THE CURRENT PRECIPITATION. SOME CONCERN THAT KRST COULD PICK SOME ACCUMULATING SNOW LATE IN THE DAY...ASSOCIATED WITH ANOTHER LOW PRESSURE SYSTEM DROPPING SOUTHEAST INTO IOWA. HOWEVER...IT APPEARS THE BULK OF THE SNOW RIGHT NOW WILL STAY SOUTH OF THE TAF SITES. NORTHWEST WINDS...WHICH COULD GUST UP TO 20 KT AT KRST...SHOULD HELP DRIVE IN DRIER AIR THURSDAY EVENING. ANTICIPATING THIS DRIER AIR TO HELP SCATTER OUT THE CLOUDS AT KRST. UNSURE IF THE DRIER AIR WILL GET INTO KLSE PRIOR TO 06Z...THUS HAVE HELD ONTO THE MVFR CEILING. && .ARX WATCHES/WARNINGS/ADVISORIES... 827 PM CST WED FEB 13 2013 WI...WINTER WEATHER ADVISORY UNTIL NOON CST THURSDAY FOR WIZ017-029. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...WETENKAMP AVIATION...AJ
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1019 PM MST WED FEB 13 2013 .AVIATION...06Z TAFS HAVE A COLD FRONT THAT IS FORECAST TO MOVE INTO THE PANHANDLE AND SOUTHEAST WYOMING OVERNIGHT INTO THURSDAY MORNING. LATEST SREF AND HRRR GUIDANCE FORECASTING A BAND OF IFR DEVELOPING OVER THE CENTRAL PANHANDLE AROUND THE 10Z TIMEFRAME...PERSISTING THROUGH LATE MORNING. CONFIDENCE MEDIUM IN THIS HAPPENING AS WE DO HAVE A BAND OF SNOW IN THAT SAME GENERAL AREA RIGHT NOW. SO THIS GUIDANCE IS SHOWING IT EXPANDING A LITTLE MORE LATER IN THE MORNING. WENT AHEAD WITH SOME IFR CONDITIONS FOR KAIA...KSNY AND POSSIBLY KBFF. 01Z HRRR HAS THIS BAND JUST EAST OF KCYS AROUND 14Z...SO KEPT IT OUT OF THE TAF FOR NOW. LATER SHIFT WILL NEED TO MONITOR CLOSELY. OUT WEST FOR KRWL AND KLAR...THINK SNOW WILL DEVELOP AS THIS FRONT MOVES THROUGH THAT AREA...BRINGING A PERIOD OF IFR CONDITIONS. THIS WOULD BE MORE THE 12Z FORECAST CHALLENGE. BEHIND THE FRONT...VERY STRONG NORTHWEST WINDS EXPECTED IN THE PANHANDLE...WITH GUSTS TO 40KTS AT ALL LOCATIONS THROUGH 00Z. CLAYCOMB && .PREV DISCUSSION... /ISSUED 606 PM MST WED FEB 13 2013/ UPDATE... WINDS IN THE WARNED AREA...NAMELY BORDEAUX...ARLINGTON AND THE SOUTHERN LARAMIE RANGE HAVE SHOWN STEADY DECREASES THE PAST COUPLE HOURS. WENT AHEAD AND ALLOWED THE HIGH WIND WARNING TO EXPIRE ON TIME AT 6 PM. GETTING SOME LIGHT SNOW BEING REPORTED IN THE NORTHERN PANHANDLE AS WELL. RADAR IS SHOWING A BAND OF ENHANCED SNOW SHOWERS ROUGHLY FROM ALLIANCE TO TORRINGTON TO WHEATLAND MOVING SOUTH. WENT AHEAD AND ADDED SOME SMALL CHANCE POPS FURTHER SOUTH THAN WHAT WE HAD PREVIOUS. UPDATES HAVE BEEN SENT. CLAYCOMB PREV DISCUSSION... /ISSUED 401 PM MST WED FEB 13 2013/ SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT... STILL GETTING OCCASIONAL WIND GUSTS TO 45-50 MPH ACROSS THE WIND PRONE AREAS THIS AFTERNOON...HOWEVER THE TREND HAS BEEN DOWNWARD SINCE LATE MORNING. WILL KEEP THE HIGH WIND WARNING GOING THROUGH 6 PM AS THE GFS SHOWS 700MB WINDS AROUND 45 KTS THROUGH 00Z THURS AND THE 700MB CAG-CPR GRADIENT REMAINS ABOVE 40 METERS. STILL EXPECTING WINDS TO CONSISTENTLY DROP BELOW 50 MPH BY LATE THIS EVENING OVER THE WIND PRONE AREAS AS THE LLVL GRADIENT DECREASES FURTHER AND THE LLVL WINDS HAVE A MORE NORTHWESTERLY ORIENTATION. PRETTY STRONG SHORTWAVE MOVING SOUTHWARD OVER THE NORTHERN PLAINS OVERNIGHT WILL DRIVE A COLD FRONT ACROSS THE AREA BY THURSDAY MORNING. FOCUS FOR THE STRONGER WINDS WILL SHIFT EASTWARD OVER THE PANHANDLE ZONES BY THURSDAY MORNING. DECIDED TO ISSUE A WIND ADVISORY FROM THURSDAY MORNING THROUGH THE AFTERNOON BASED ON SOME FAVORABLE INGREDIENTS. THE GFS SHOWS NORTHWESTERLY 700MB FLOW AROUND 50 KTS BY 18Z THURS ALONG WITH GOOD SUBSIDENCE (COLD AIR ADVECTION) BEHIND THE SHORTWAVE. IN ADDITION...LLVL LAPSE RATES ARE EXCELLENT BY LATE MORNING OVER THE PANHANDLE WITH 35-40 KTS OF UNIDIRECTIONAL FLOW IN THE MIXED LAYER. SINCE SEVERAL SITES IN THE PANHANDLE WERE CLOSE TO HITTING 45 MPH GUSTS THIS AFTERNOON...BELIEVE THAT GUSTS TO 45-50 MPH WILL DEFINITELY BE POSSIBLE TOMORROW. THERE WILL BE A GOOD AMOUNT OF 700-500MB MOISTURE IN THE NORTHWESTERLY FLOW THURSDAY MORNING THROUGH FRIDAY MORNING...WITH THE AXIS OVER SOUTHEAST WY. THE GFS AND THE NAM SHOW WEAK MIDLEVEL FRONTOGENESIS ACROSS EXTREME SOUTHEAST WYOMING/NEBRASKA PANHANDLE ON THURS AFTN. HIGHEST QPF ON THURS AFTN IS GENERALLY WEST OF THE LARAMIE RANGE (TO THE WEST OF THE FRONTOGENESIS AXIS)...SO COULD SEE SOME ENHANCEMENT IN SNOWFALL RATES AT THAT TIME. HOWEVER...SNOWFALL AMOUNTS ACROSS THE LOWER ELEVATIONS WILL GENERALLY BE LESS THAN AN INCH THROUGH FRIDAY MORNING. DO HAVE SNOWFALL AMOUNTS OF 6 TO 9 INCHES IN THE SIERRA MADRE AND SNOWY RANGES FROM TONIGHT THROUGH FRIDAY MORNING. SINCE SNOWFALL RATES WILL BE LIGHT WITH THIS EVENT...AND BLOWING SNOW WILL NOT BE MUCH OF A PROBLEM OVER SOUTHEAST WY...DECIDED TO HOLD OFF ON ISSUING A MARGINAL WINTER WEATHER ADVISORY. THIS IS ONE OF THOSE HIGHER ACCUMULATION BUT LONG DURATION EVENTS OVER THE MTNS. WILL CONTINUE TO HIGHLIGHT THE SNOWFALL ACCUMULATIONS IN THE MTNS IN THE HWO AND SPS. TEMPS WILL OBVIOUSLY BE COLDER ON THURS BEHIND THE FROPA AS 700MB TEMPS DROP DOWN TO -14C. A FINAL SHORTWAVE DIVES DOWN INTO THE NORTHERN AND CENTRAL PLAINS ON FRIDAY BEFORE THE LONG WAVE TROUGH QUICKLY SHIFTS EASTWARD. THIS SHORTWAVE WILL MAINTAIN THE COLD NORTHWESTERLY FLOW OVER THE REGION FOR ONE MORE DAY. ANOTHER SLUG OF 700-500MB MOISTURE MOVES OVER THE AREA FROM FRIDAY MORNING INTO THE AFTN BEFORE THE MIDLEVELS DRY OUT. A LIGHT QPF EVENT COULD BE IN STORE WITH THIS SHORTWAVE...WITH SNOW AMOUNTS LIMITED BY WEAK DYNAMICS AND QUITE PROGRESSIVE NATURE OF THE SYSTEM. LONG TERM...SATURDAY THROUGH WEDNESDAY.... MILD AND MAINLY DRY WEATHER EXPECTED SATURDAY AND SUNDAY AS UPPER RIDGE TRANSLATES ACROSS THE REGION. SOME WINDINESS WILL OCCUR MAINLY SATURDAY AS SFC LEE TROF SETS UP OVER THE HIGH PLAINS INCREASING THE SFC PRESSURE GRADIENT. BY LATE SUNDAY UPPER SHORTWAVE WILL MOVE INTO THE NRN ROCKIES AND PROCEED INTO THE NORTHERN PLAINS AND CENTRAL ROCKIES SUNDAY NIGHT INTO MONDAY. THIS WILL PUSH NEXT COLD FRONT ACROSS THE AREA LATE SUNDAY AS WELL AS BRING SOME SNOW OR SNOW SHOWERS. PROGRESSIVE UPPER FLOW ALLOWS NEXT UPPER RIDGE TO PASS ACROSS MONDAY NIGHT WHILE NEXT MORE SIGNIFICANT UPPER TROF MOVES ONSHORE ALONG THE WEST COAST. WARMER AGAIN TUESDAY THEN EFFECTS OF THIS NEXT UPPER TROF SHOULD ARRIVE WEDS WITH SNOW AND SNOW SHOWERS SPREADING OVER MAINLY THE WY PORTION OF THE CWA ALONG WITH COOLER TEMPERATURES. WILL HAVE TO WATCH THIS SYSTEM CLOSELY AS IT HAS SOME POTENTIAL TO BE SIGNIFICANT. && FIRE WEATHER... MINIMAL FIRE WEATHER CONCERNS THROUGH FRIDAY. TEMPERATURES WILL BE AROUND 10-15 DEGREES BELOW NORMAL ON THURSDAY AND FRIDAY. MINIMUM AFTERNOON HUMIDITIES WILL GENERALLY BE ABOVE 40 PERCENT. THERE WILL BE ISOLATED TO WIDELY SCATTERED SNOW SHOWERS THURSDAY MORNING THROUGH FRIDAY MORNING OVER THE PLAINS...HOWEVER ACCUMULATIONS ARE EXPECTED TO BE LESS THAN AN INCH. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...WIND ADVISORY FROM 8 AM THURSDAY TO 4 PM THURSDAY FOR NEZ002- NEZ003-NEZ019-NEZ020-NEZ021-NEZ054-NEZ055-NEZ095-NEZ096. && $$ SHORT TERM/FIRE WEATHER...FINCH LONG TERM/AVIATION...RE
AREA FORECAST DISCUSSION
NWS ALBANY NY
113 AM EST SAT FEB 16 2013 .SYNOPSIS... TONIGHT THROUGH SATURDAY NIGHT...WAVES OF LOW PRESSURE WILL MOVE FROM THE MID ATLANTIC COAST TO WELL SOUTH AND EAST OF LONG ISLAND BRINGING A LIGHT SNOWFALL FROM THE MID HUDSON VALLEY INTO WESTERN NEW ENGLAND. THE WAVES OF LOW PRESSURE WILL MERGE INTO A POWERFUL STORM EAST OF THE GULF OF MAINE BRINGING BLUSTERY AND COLD CONDITIONS FOR SUNDAY...BUT WITH THE BULK OF SNOWFALL OCCURRING ACROSS COASTAL NEW ENGLAND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1230 PM EST...HAD TO MAKE SOME CHANGES NAMELY TO REFLECT THE FACT THAT LIGHT SNOW DEVELOPED MORE QUICKLY THAN ORIGINALLY THOUGHT OVER THE CAPITAL DISTRICT AND EVEN POINTS TO THE SOUTH. INCREASED POPS TO HIGH LIKELY OR EVEN CATEGORICAL IN THESE AREAS SINCE INDEED IT IS EITHER SNOW (OR RAINING SOUTH WHERE SURFACE TEMPERATURES WERE TOO WARM TO SUPPORT SNOW YET). HOWEVER...WITH EVAPORATIVE COOLING WE ARE CONFIDENT THAT THE RAIN WILL CHANGE TO SNOW IN THESE AREAS IN A FEW HOURS. OTHERWISE...JUST RE-TOOLED THE HOURLY GRIDS...ESPECIALLY TEMPERATURES WHICH HAD DROPPED THE FASTEST THE SNOW WAS FALLING. HOWEVER...OVERNIGHT LOWS STILL LOOK REASONABLE SO LEFT THEM ALONE. THE LATEST RUC13 INDICATES AN AREA OF ENHANCED 850-700 MB FRONTOGENETICAL FORCING ACROSS EASTERN PA EXTENDING INTO EASTERN NYS...AND THIS AREA HAS EXPANDED NE. IT WILL THEN GRADUALLY SHIFT EASTWARD A FEW HOURS AFTER MIDNIGHT. FOR AREAS MAINLY S AND E OF ALBANY...THE PRECIPITATION AREA SHOULD CONTINUE EXPANDING N AND E THROUGH AROUND 2 AM...BEFORE SHIFTING SLOWLY EAST. BOUNDARY LAYER TEMPS REMAIN SOMEWHAT MILD...AND SHOULD ALLOW FOR PRECIP TO BEGIN MAINLY AS LIGHT RAIN IN VALLEY AREAS...WITH A RAIN/SNOW MIX ACROSS HIGHER ELEVATIONS. HOWEVER...AFTER ABOUT 1-2 HOURS OF EVAPORATIONAL COOLING...EVEN VALLEY AREAS SHOULD TRANSITION TO SNOW AROUND OR JUST AFTER MIDNIGHT...WITH HIGHER ELEVATIONS CHANGING OVER MORE QUICKLY. STILL EXPECT SNOWFALL TOTALS OF AROUND AN INCH FOR HUDSON VALLEY LOCATIONS...WITH PERHAPS 1-3 INCHES FOR AREAS E OF THE HUDSON RIVER INTO NW CT...AND EASTERN DUTCHESS CO. FURTHER N AND W...STILL EXPECT MAINLY UNDER AN INCH...WITH PERHAPS 1-2 INCHES ACROSS PORTIONS OF THE SOUTHERN BERKSHIRES. THE GREATER CAPITAL DISTRICT AND POINTS TO THE NORTH WILL RECEIVE A COATING TO AN INCH OF SNOWFALL. AS FOR MIN TEMPS...GIVEN THE ABUNDANT CLOUD COVER OVERNIGHT...AND THE FACT THAT CURRENT TEMPS ARE RUNNING A BIT WARMER THAN PREVIOUS GUIDANCE SUGGESTED...HAVE RAISED MINS BY ABOUT 1-3 DEGREES IN MOST AREAS...WITH MID/UPPER 20S EXPECTED WITHIN THE HUDSON RIVER VALLEY FROM ALBANY SOUTH...AND TEENS TO LOWER/MID 20S ACROSS THE SOUTHERN ADIRONDACKS. ELSEWHERE...EXPECT MAINLY LOWER/MID 20S. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/... ANOTHER WAVE OF LOW PRESSURE MERGES OFFSHORE NEW ENGLAND AND RAPID STRENGTHENING OF THE SYSTEM SHOULD OCCUR AS AN UPPER CUT OFF LOW INTERACTS WITH THE SYSTEM. CONSENSUS FROM GUIDANCE AND ENSEMBLES SUGGESTS THE STORM TRACKS TOO FAR EAST TO REALLY IMPACT OUR FORECAST AREA...WITH PERHAPS JUST SOME ADDITIONAL LIGHT ACCUMULATION FOR WESTERN NEW ENGLAND SATURDAY NIGHT AND EARLY SUNDAY MORNING. STILL THERE SHOULD BE ENOUGH CLOUD COVER AND LIGHT WINDS TO KEEP HIGH TEMPERATURES A LITTLE BELOW NORMAL...IN THE LOWER TO MID 30S...20S IN HIGHER TERRAIN. AS THE STORM RAPIDLY STRENGTHENS AND TRACKS INTO SOUTHEASTERN CANADA...THE MEAN UPPER TROUGH AXIS BUILDS EAST AND VERY COLD AIR SPILLS EAST INTO OUR REGION. THE TIGHT PRESSURE GRADIENT AROUND THE STRONG LOW PRESSURE SHOULD SUPPORT STRONG WINDS THROUGHOUT THE NORTHEASTERN U.S. MAKING FOR A NOTICEABLY COLD DAY SUNDAY. THERE COULD BE WIND CHILL ISSUES AND MAYBE BORDERING ON WIND ADVISORY WIND SPEEDS IN SOME AREAS. HIGHS SUNDAY IN THE LOWER TO MID 20S...SOME UPPER 20S SOUTHERN AREAS AND TEENS IN HIGHER TERRAIN. THE STORM IS PREDICTED TO BE SLOW TO EXIT...AND THE WINDS MAY DIMINISH ONLY GRADUALLY SUNDAY NIGHT INTO MONDAY. AGAIN...THERE MAY BE SOME WIND CHILL ISSUES IN SOME AREAS...ESPECIALLY SUNDAY NIGHT. LOWS SUNDAY NIGHT IN THE SINGLE NUMBERS TO LOWER TEENS...AROUND OR JUST BELOW ZERO IN COLDER AREAS. HIGHS MONDAY IN THE UPPER 20S TO LOWER 30S...LOWER 20S IN HIGHER TERRAIN. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... MONDAY NIGHT...A RIDGE OF HIGH PRESSURE WILL SLIDE EASTWARD ACROSS THE REGION...WHICH SHOULD BRING GENERALLY DRY CONDITIONS...WITH DECREASING WIND. SOME HIGH/MID LEVEL CLOUDS MAY INCREASE LATE AT NIGHT IN ADVANCE OF A SYSTEM APPROACHING FROM THE SOUTHWEST. EXPECT ANOTHER COLD NIGHT...WITH MINS FALLING INTO THE SINGLE DIGITS ACROSS NORTHERN AREAS...AND TEENS ELSEWHERE. TUE-TUE NT...MODELS CONTINUE PREVIOUS TRENDS OF A MORE PROGRESSIVE...AND FURTHER NORTH TRACK OF A SYSTEM DURING THIS TIME PERIOD. STRONG WARM ADVECTION IN ADVANCE OF THIS SYSTEM SHOULD STILL BRING A PERIOD OF PRECIPITATION TO THE REGION...MOST LIKELY TUE AFTERNOON AND NIGHT...ALTHOUGH IT COULD START AS EARLY AS TUE MORNING. FORECAST SOUNDINGS INDICATE MUCH OF THE REGION SHOULD BE COLD ENOUGH TO SUPPORT MAINLY SNOW...ALTHOUGH BOUNDARY LAYER TEMPS...AND SOME WARMING WITHIN THE 925-850 LAYER COULD ALLOW FOR SOME RAIN TO MIX IN...ESP FOR AREAS SOUTH OF INTERSTATE 90 TUE AFTERNOON. WILL INDICATE CHC POPS FOR THIS TIME PERIOD...WITH MAINLY SNOW FOR NORTHERN AREAS...AND A RAIN/SNOW MIX FOR CENTRAL AND SOUTHERN AREAS DEVELOPING BY TUE AFTERNOON...WITH PRECIPITATION CHANGING TO SNOW ALL AREAS FOR TUE NT. MODELS HAVE TRENDED TOWARD LESS OVERALL QPF...WITH THE 12Z/GEM REMAINING THE WETTER OUTLIER ALLOWING FOR MORE SECONDARY COASTAL DEVELOPMENT FOR TUE NT. ASSUMING THE 12Z/GFS/GEFS AND ECMWF PROVE CORRECT...IT APPEARS THAT THIS EVENT SHOULD MAINLY COMPRISE OF LIGHT TO PERHAPS MODERATE PRECIPITATION AMTS. WED-THU NT...AS THE REMNANT UPPER LEVEL TROUGH PASSES NORTH OF THE REGION WED AND WED EVENING...THE DEEP CYCLONIC FLOW WITHIN COLD AIR ADVECTION SHOULD PROMOTE SCATTERED SNOW SHOWERS ACROSS MUCH OF THE REGION...WITH THE MORE PERSISTENT SNOW SHOWERS ACROSS TRADITIONALLY FAVORED AREAS OF THE WESTERN ADIRONDACKS...MOHAWK VALLEY...AND POSSIBLY ACROSS THE SOUTHERN GREENS AND NORTHERN BERKSHIRES. THE SNOW SHOWERS SHOULD DIMINISH IN AREAL COVERAGE LATE WED INTO WED NT...FOLLOWED BY FAIR AND COLD CONDITIONS FOR THU INTO THU NT WITH BELOW NORMAL TEMPS. SO...FOR MAX TEMPS...EXPECT LOWER/MID 30S IN VALLEYS WED...WITH MAINLY 20S ACROSS HIGHER ELEVATIONS...WITH MAX TEMPS A FEW DEGREES COLDER FOR THU. FOR MINS...EXPECT MAINLY 20S ACROSS VALLEY REGIONS AND ADJACENT WESTERN NEW ENGLAND FOR WED AM GIVEN CLOUDS AND SOME WIND...THEN TEENS IN LOWER ELEVATIONS...AND SINGLE DIGITS ACROSS HIGHER ELEVATIONS FOR THU AM AND THU NT/FRI AM. FRI...PREVIOUS RUNS OF VARIOUS GLOBAL DETERMINISTIC MODELS AND ENSEMBLES HAVE INDICATED ANOTHER POTENTIAL STORM SYSTEM APPROACHING THE REGION SOMETIME LATE FRI INTO NEXT WEEKEND. SEVERAL 12Z/15 MODELS HAVE TRENDED WEAKER...AND FURTHER SOUTH WITH ANY POTENTIAL SYSTEM...GIVEN STRENGTHENING UPPER LEVEL RIDGING/BLOCKING ACROSS CENTRAL/EASTERN CANADA. STILL A GREAT DEAL OF UNCERTAINTY AT THIS TIME RANGE...SO HAVE MAINTAINED CHC POPS FOR FRI...WITH THERMAL PROFILES SUGGESTING ALL SNOW. EXPECT MAX TEMPS TO POTENTIALLY REACH 30-35 IN LOWER ELEVATIONS...AND 20S FOR HIGHER TERRAIN. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AN UPPER LEVEL DISTURBANCE WILL PASS ACROSS SOUTHERN PORTIONS OF THE REGION LATE TONIGHT. THIS DISTURBANCE WILL BRING WIDESPREAD LIGHT SNOW TO KPOU/KPSF UNTIL SHORTLY BEFORE SUNRISE...AND THROUGH 07Z/08Z AT KALB. AT KGFL LITTLE OR NO SNOW IS EXPECTED. ANY IFR CONDITIONS AT KALB WILL END BY AROUND 07Z...BUT NOT UNTIL AROUND 10Z AT KPOU AND KPSF. AT KGFL CONDITIONS WILL GET NO LOWER THAN MVFR. AFTER 12Z...EXPECT VFR CONDITIONS AT ALL THE TAF SIDES FOR THE REST OF THE TAF PERIOD ENDING AT 06Z SUNDAY. WINDS WILL BE NORTH TO NORTHWEST AT LESS THAN 8 KTS THROUGH EARLY SATURDAY MORNING...THEN INCREASE TO 8 TO 10 KTS BY LATE MORNING WITH SOME GUSTS TO 15 KTS POSSIBLE...ESPECIALLY AT KALB. THESE WINDS WILL PERSIST THROUGH 06Z SUNDAY. OUTLOOK... LATE SAT NT-MON NT...VFR. NO SIG WX. TUE...MVFR/IFR TUE WITH MIXED PCPN. TUE NITE-WED...MAINLY VFR. CHC MVFR -SHSN. && .HYDROLOGY... NO HYDROLOGY PROBLEMS ARE EXPECTED OVER THE NEXT FEW DAYS. SNOW MELT WILL CONTINUE TO BE GRADUAL THROUGH SATURDAY WITH ABOVE FREEZING TEMPERATURES DURING THE DAY...AND BELOW FREEZING AT NIGHT. TEMPERATURES WILL BECOME COLDER FOR THE 2ND HALF OF THE WEEKEND SLOWING...AND EVEN ENDING THE SNOWMELT. THE PREDOMINANT PTYPE TODAY INTO THE MID WEEK WILL BE SNOW. THE SYSTEMS DURING THAT TIME FRAME ARE EXPECTED TO ONLY PRODUCE LIGHT SNOW AMOUNTS. THEREFORE...NO IMPACTS ARE EXPECTED ON THE ALY HSA WATERWAYS. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...NAS NEAR TERM...HWJIV/KL SHORT TERM...NAS LONG TERM...KL AVIATION...GJM HYDROLOGY...NAS
AREA FORECAST DISCUSSION
NWS ALBANY NY
1225 AM EST SAT FEB 16 2013 .SYNOPSIS... TONIGHT THROUGH SATURDAY NIGHT...WAVES OF LOW PRESSURE WILL MOVE FROM THE MID ATLANTIC COAST TO WELL SOUTH AND EAST OF LONG ISLAND BRINGING A LIGHT SNOWFALL FROM THE MID HUDSON VALLEY INTO WESTERN NEW ENGLAND. THE WAVES OF LOW PRESSURE WILL MERGE INTO A POWERFUL STORM EAST OF THE GULF OF MAINE BRINGING BLUSTERY AND COLD CONDITIONS FOR SUNDAY...BUT WITH THE BULK OF SNOWFALL OCCURRING ACROSS COASTAL NEW ENGLAND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1230 PM EST...HAD TO MAKE SOME CHANGES NAMELY TO REFLECT THE FACT THAT LIGHT SNOW DEVELOPED MORE QUICKLY THAN ORIGINALLY THOUGHT OVER THE CAPITAL DISTRICT AND EVEN POINTS TO THE SOUTH. INCREASED POPS TO HIGH LIKELY OR EVEN CATEGORICAL IN THESE AREAS SINCE INDEED IT IS EITHER SNOW (OR RAINING SOUTH WHERE SURFACE TEMPERATURES WERE TOO WARM TO SUPPORT SNOW YET). HOWEVER...WITH EVAPORATIVE COOLING WE ARE CONFIDENT THAT THE RAIN WILL CHANGE TO SNOW IN THESE AREAS IN A FEW HOURS. OTHERWISE...JUST RE-TOOLED THE HOURLY GRIDS...ESPECIALLY TEMPERATURES WHICH HAD DROPPED THE FASTEST THE SNOW WAS FALLING. HOWEVER...OVERNIGHT LOWS STILL LOOK REASONABLE SO LEFT THEM ALONE. THE LATEST RUC13 INDICATES AN AREA OF ENHANCED 850-700 MB FRONTOGENETICAL FORCING ACROSS EASTERN PA EXTENDING INTO EASTERN NYS...AND THIS AREA HAS EXPANDED NE. IT WILL THEN GRADUALLY SHIFT EASTWARD A FEW HOURS AFTER MIDNIGHT. FOR AREAS MAINLY S AND E OF ALBANY...THE PRECIPITATION AREA SHOULD CONTINUE EXPANDING N AND E THROUGH AROUND 2 AM...BEFORE SHIFTING SLOWLY EAST. BOUNDARY LAYER TEMPS REMAIN SOMEWHAT MILD...AND SHOULD ALLOW FOR PRECIP TO BEGIN MAINLY AS LIGHT RAIN IN VALLEY AREAS...WITH A RAIN/SNOW MIX ACROSS HIGHER ELEVATIONS. HOWEVER...AFTER ABOUT 1-2 HOURS OF EVAPORATIONAL COOLING...EVEN VALLEY AREAS SHOULD TRANSITION TO SNOW AROUND OR JUST AFTER MIDNIGHT...WITH HIGHER ELEVATIONS CHANGING OVER MORE QUICKLY. STILL EXPECT SNOWFALL TOTALS OF AROUND AN INCH FOR HUDSON VALLEY LOCATIONS...WITH PERHAPS 1-3 INCHES FOR AREAS E OF THE HUDSON RIVER INTO NW CT...AND EASTERN DUTCHESS CO. FURTHER N AND W...STILL EXPECT MAINLY UNDER AN INCH...WITH PERHAPS 1-2 INCHES ACROSS PORTIONS OF THE SOUTHERN BERKSHIRES. THE GREATER CAPITAL DISTRICT AND POINTS TO THE NORTH WILL RECEIVE A COATING TO AN INCH OF SNOWFALL. AS FOR MIN TEMPS...GIVEN THE ABUNDANT CLOUD COVER OVERNIGHT...AND THE FACT THAT CURRENT TEMPS ARE RUNNING A BIT WARMER THAN PREVIOUS GUIDANCE SUGGESTED...HAVE RAISED MINS BY ABOUT 1-3 DEGREES IN MOST AREAS...WITH MID/UPPER 20S EXPECTED WITHIN THE HUDSON RIVER VALLEY FROM ALBANY SOUTH...AND TEENS TO LOWER/MID 20S ACROSS THE SOUTHERN ADIRONDACKS. ELSEWHERE...EXPECT MAINLY LOWER/MID 20S. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/... ANOTHER WAVE OF LOW PRESSURE MERGES OFFSHORE NEW ENGLAND AND RAPID STRENGTHENING OF THE SYSTEM SHOULD OCCUR AS AN UPPER CUT OFF LOW INTERACTS WITH THE SYSTEM. CONSENSUS FROM GUIDANCE AND ENSEMBLES SUGGESTS THE STORM TRACKS TOO FAR EAST TO REALLY IMPACT OUR FORECAST AREA...WITH PERHAPS JUST SOME ADDITIONAL LIGHT ACCUMULATION FOR WESTERN NEW ENGLAND SATURDAY NIGHT AND EARLY SUNDAY MORNING. STILL THERE SHOULD BE ENOUGH CLOUD COVER AND LIGHT WINDS TO KEEP HIGH TEMPERATURES A LITTLE BELOW NORMAL...IN THE LOWER TO MID 30S...20S IN HIGHER TERRAIN. AS THE STORM RAPIDLY STRENGTHENS AND TRACKS INTO SOUTHEASTERN CANADA...THE MEAN UPPER TROUGH AXIS BUILDS EAST AND VERY COLD AIR SPILLS EAST INTO OUR REGION. THE TIGHT PRESSURE GRADIENT AROUND THE STRONG LOW PRESSURE SHOULD SUPPORT STRONG WINDS THROUGHOUT THE NORTHEASTERN U.S. MAKING FOR A NOTICEABLY COLD DAY SUNDAY. THERE COULD BE WIND CHILL ISSUES AND MAYBE BORDERING ON WIND ADVISORY WIND SPEEDS IN SOME AREAS. HIGHS SUNDAY IN THE LOWER TO MID 20S...SOME UPPER 20S SOUTHERN AREAS AND TEENS IN HIGHER TERRAIN. THE STORM IS PREDICTED TO BE SLOW TO EXIT...AND THE WINDS MAY DIMINISH ONLY GRADUALLY SUNDAY NIGHT INTO MONDAY. AGAIN...THERE MAY BE SOME WIND CHILL ISSUES IN SOME AREAS...ESPECIALLY SUNDAY NIGHT. LOWS SUNDAY NIGHT IN THE SINGLE NUMBERS TO LOWER TEENS...AROUND OR JUST BELOW ZERO IN COLDER AREAS. HIGHS MONDAY IN THE UPPER 20S TO LOWER 30S...LOWER 20S IN HIGHER TERRAIN. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... MONDAY NIGHT...A RIDGE OF HIGH PRESSURE WILL SLIDE EASTWARD ACROSS THE REGION...WHICH SHOULD BRING GENERALLY DRY CONDITIONS...WITH DECREASING WIND. SOME HIGH/MID LEVEL CLOUDS MAY INCREASE LATE AT NIGHT IN ADVANCE OF A SYSTEM APPROACHING FROM THE SOUTHWEST. EXPECT ANOTHER COLD NIGHT...WITH MINS FALLING INTO THE SINGLE DIGITS ACROSS NORTHERN AREAS...AND TEENS ELSEWHERE. TUE-TUE NT...MODELS CONTINUE PREVIOUS TRENDS OF A MORE PROGRESSIVE...AND FURTHER NORTH TRACK OF A SYSTEM DURING THIS TIME PERIOD. STRONG WARM ADVECTION IN ADVANCE OF THIS SYSTEM SHOULD STILL BRING A PERIOD OF PRECIPITATION TO THE REGION...MOST LIKELY TUE AFTERNOON AND NIGHT...ALTHOUGH IT COULD START AS EARLY AS TUE MORNING. FORECAST SOUNDINGS INDICATE MUCH OF THE REGION SHOULD BE COLD ENOUGH TO SUPPORT MAINLY SNOW...ALTHOUGH BOUNDARY LAYER TEMPS...AND SOME WARMING WITHIN THE 925-850 LAYER COULD ALLOW FOR SOME RAIN TO MIX IN...ESP FOR AREAS SOUTH OF INTERSTATE 90 TUE AFTERNOON. WILL INDICATE CHC POPS FOR THIS TIME PERIOD...WITH MAINLY SNOW FOR NORTHERN AREAS...AND A RAIN/SNOW MIX FOR CENTRAL AND SOUTHERN AREAS DEVELOPING BY TUE AFTERNOON...WITH PRECIPITATION CHANGING TO SNOW ALL AREAS FOR TUE NT. MODELS HAVE TRENDED TOWARD LESS OVERALL QPF...WITH THE 12Z/GEM REMAINING THE WETTER OUTLIER ALLOWING FOR MORE SECONDARY COASTAL DEVELOPMENT FOR TUE NT. ASSUMING THE 12Z/GFS/GEFS AND ECMWF PROVE CORRECT...IT APPEARS THAT THIS EVENT SHOULD MAINLY COMPRISE OF LIGHT TO PERHAPS MODERATE PRECIPITATION AMTS. WED-THU NT...AS THE REMNANT UPPER LEVEL TROUGH PASSES NORTH OF THE REGION WED AND WED EVENING...THE DEEP CYCLONIC FLOW WITHIN COLD AIR ADVECTION SHOULD PROMOTE SCATTERED SNOW SHOWERS ACROSS MUCH OF THE REGION...WITH THE MORE PERSISTENT SNOW SHOWERS ACROSS TRADITIONALLY FAVORED AREAS OF THE WESTERN ADIRONDACKS...MOHAWK VALLEY...AND POSSIBLY ACROSS THE SOUTHERN GREENS AND NORTHERN BERKSHIRES. THE SNOW SHOWERS SHOULD DIMINISH IN AREAL COVERAGE LATE WED INTO WED NT...FOLLOWED BY FAIR AND COLD CONDITIONS FOR THU INTO THU NT WITH BELOW NORMAL TEMPS. SO...FOR MAX TEMPS...EXPECT LOWER/MID 30S IN VALLEYS WED...WITH MAINLY 20S ACROSS HIGHER ELEVATIONS...WITH MAX TEMPS A FEW DEGREES COLDER FOR THU. FOR MINS...EXPECT MAINLY 20S ACROSS VALLEY REGIONS AND ADJACENT WESTERN NEW ENGLAND FOR WED AM GIVEN CLOUDS AND SOME WIND...THEN TEENS IN LOWER ELEVATIONS...AND SINGLE DIGITS ACROSS HIGHER ELEVATIONS FOR THU AM AND THU NT/FRI AM. FRI...PREVIOUS RUNS OF VARIOUS GLOBAL DETERMINISTIC MODELS AND ENSEMBLES HAVE INDICATED ANOTHER POTENTIAL STORM SYSTEM APPROACHING THE REGION SOMETIME LATE FRI INTO NEXT WEEKEND. SEVERAL 12Z/15 MODELS HAVE TRENDED WEAKER...AND FURTHER SOUTH WITH ANY POTENTIAL SYSTEM...GIVEN STRENGTHENING UPPER LEVEL RIDGING/BLOCKING ACROSS CENTRAL/EASTERN CANADA. STILL A GREAT DEAL OF UNCERTAINTY AT THIS TIME RANGE...SO HAVE MAINTAINED CHC POPS FOR FRI...WITH THERMAL PROFILES SUGGESTING ALL SNOW. EXPECT MAX TEMPS TO POTENTIALLY REACH 30-35 IN LOWER ELEVATIONS...AND 20S FOR HIGHER TERRAIN. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AN UPPER LEVEL DISTURBANCE WILL PASS ACROSS SOUTHERN PORTIONS OF THE REGION LATER TONIGHT. THIS DISTURBANCE WILL BRING WIDESPREAD MID LEVEL CLOUDS OVERNIGHT...ALONG WITH A BRIEF PERIOD OF LIGHT SNOW AT KPOU AND KPSF AFTER MIDNIGHT...WHICH COULD INITIALLY BE MIXED WITH RAIN. KALB APPEARS TO BE ON THE NORTHWEST EDGE OF THE DEVELOPING PRECIPITATION SHIELD...AND WILL ONLY INDICATE VCSH FOR NOW UNLESS RADAR TRENDS INDICATE OTHERWISE LATER THIS EVENING. IN AREAS WHERE THE SNOW DEVELOPS...A PERIOD OF MVFR OR POSSIBLE IFR VSBYS AND CIGS WILL BE POSSIBLE BETWEEN 06Z-10Z/SAT. ELSEWHERE...MAINLY VFR CONDITIONS ARE EXPECTED THROUGH DAYBREAK. ON SATURDAY...AREAS OF MVFR CIGS COULD LINGER AT KPOU AND KPSF THROUGH AROUND 15Z. OTHERWISE...VFR CONDITIONS ARE EXPECTED. WINDS WILL BECOME MAINLY NORTHWEST OVERNIGHT AT GENERALLY LESS THAN 7 T. WINDS WILL BECOME NORTH TO NORTHWEST ON SATURDAY AT GENERALLY 5-10 KT...ALTHOUGH MAY BE A BIT STRONGER AT KALB AND KPSF...ESP FROM LATE MORNING INTO THE AFTERNOON HOURS. OUTLOOK... SAT NT-TUE NT...VFR. NO SIG WX. WED...VFR BCMG MVFR/IFR. -SN/-RA POSSIBLE IN AFTERNOON. && .HYDROLOGY... NO HYDROLOGY PROBLEMS ARE EXPECTED OVER THE NEXT FEW DAYS. SNOW MELT WILL CONTINUE TO BE GRADUAL THROUGH SATURDAY WITH ABOVE FREEZING TEMPERATURES DURING THE DAY...AND BELOW FREEZING AT NIGHT. TEMPERATURES WILL BECOME COLDER FOR THE 2ND HALF OF THE WEEKEND SLOWING...AND EVEN ENDING THE SNOWMELT. THE PREDOMINANT PTYPE TODAY INTO THE MID WEEK WILL BE SNOW. THE SYSTEMS DURING THAT TIME FRAME ARE EXPECTED TO ONLY PRODUCE LIGHT SNOW AMOUNTS. THEREFORE...NO IMPACTS ARE EXPECTED ON THE ALY HSA WATERWAYS. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...NAS NEAR TERM...HWJIV/KL SHORT TERM...NAS LONG TERM...KL AVIATION...KL HYDROLOGY...NAS
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1135 PM CST FRI FEB 15 2013 ...UPDATE TO AVIATION... .DISCUSSION... 12Z UPPER AIR DATA DEPICTED AT 130KT JET DIVING SOUTH OUT OF WESTERN SASKATCHEWAN WITH WIDESPREAD 500MB TEMPS OF AROUND -40C OVER THE NORTHERN PLAINS AND EASTERN CANADA. AN UPPER LEVEL TROF WAS MAKING SOUTHWARD PROGRESS OUT OF THE WESTERN DAKOTAS IN RECENT HOURS PER WATER VAPOR IMAGERY. WEAK RADAR RETURNS HAVE DEVELOPED OVER MUCH OF NORTHERN KANSAS THOUGH DEWPOINT DEPRESSIONS AROUND 20F ARE LIKELY KEEP MUCH OF THIS WEAK ACTIVITY FROM REACHING THE GROUND. 20Z SURFACE-3KM LAPSE RATES NEAR 9C/KM WERE NOTED IN CENTRAL NEBRASKA...WITH AROUND 8C/KM VALUES EAST AND ALSO SOUTHEAST INTO THE LOCAL AREA. THE MAIN ISSUES TONIGHT ARE WHERE AND HOW LONG THE SNOW SHOWERS WILL LAST. THE VARIOUS GUIDANCE ALL POINTS TO A MORE SUSTAINED AREA OF PRECIPITATION SOMEWHERE IN NORTHEAST KANSAS...WITH THE DETAILS THE MAIN ISSUE. AS THE UPPER TROF CONTINUES SOUTH TO SOUTHEAST...THE LAPSE RATES REMAIN NEAR 8C/KM WELL INTO THE NIGHT AS FRONTOGENESIS AROUND 750MB INCREASES AND FOCUSES ON THE NORTHEAST TIP OF A DEVELOPING THETA-E RIDGE AT THIS LEVEL...RESULTING IN GOOD LIFT THROUGH THE DENDRITIC GROWTH ZONE. THE MOST RECENT HRRR AND RAP DATA HAS BEEN PUSHING THIS AREA NORTHEAST...FAVORING FAR NORTHEAST KANSAS MAINLY AROUND 03Z. HAVE INCREASED CHANCES AND AMOUNTS UP HERE...BUT STILL LIMITED MOISTURE AND THE COVERAGE OF ANY BANDS AND EXACTLY WHERE THIS WILL END UP KEEPS CHANCES BELOW LIKELY LEVELS. SOME BRIEF MODERATE SNOWFALLS CAN BE EXPECTED IN THE HEAVIEST PRECIPITATION... AND LOCAL AMOUNTS NEAR AN INCH SEEM PLAUSIBLE. ANY ACCUMULATING SNOW SHOULD END WELL BEFORE SUNRISE AS THE UPPER TROF SWINGS INTO THE MISSISSIPPI VALLEY. WESTERN AREAS SEE A QUICKLY DRYING TROPOSPHERE THIS EVENING...BUT HIGH CLOUD RETURNS THERE LATE TONIGHT AS WARM AIR ADVECTION ENSUES FROM THE UPPER PATTERN SHIFTING EAST. THOUGH INSOLATION WILL BE LIMITED AS THE CLOUDS DEEPEN SATURDAY...SOUTHWEST WINDS SHOULD SUPPORT TEMPS SEVERAL DEGREES ABOVE TODAYS LEVELS FOR CENTRAL AND WESTERN LOCATIONS. 65 SHORTWAVE RIDGING AND WARM AIR ADVECTION IS EXPECTED TO BRING WARMER TEMPS AND SUNNY SKIES TO THE AREA FOR SUNDAY. THEN THE NEXT SHORTWAVE IS EXPECTED TO MOVE ACROSS THE CENTRAL AND NORTHERN PLAINS BRINGING A COLD FRONT THROUGH THE AREA LATE SUNDAY NIGHT AND MONDAY MORNING. MODELS CONTINUE TO SHOW THE BETTER MOISTURE TO THE EAST OF THE FORECAST AREA. AND WITH THE FRONT PUSHING INTO MO BY THE LATE MORNING HOURS...PRECIP CHANCES SHOULD BE CONFINED TO FAR EASTERN KS DURING THE DAY MONDAY. TUESDAY AND WEDNESDAY LOOK TO BE IN BETWEEN SYSTEMS WITH SURFACE RIDGING BUILDING SOUTH THROUGH THE PLAINS. THIS SHOULD KEEP TEMPS FROM WARMING UP VERY MUCH. THE NEXT BIG WEATHER MAKER LOOKS TO IMPACT THE REGION WEDNESDAY NIGHT AND THURSDAY. BOTH THE GFS AND ECMWF HAVE TRENDED SLIGHTLY SLOWER WITH THE UPPER CLOSED LOW AS IT MOVES OUT OF THE SOUTHERN ROCKIES. HOWEVER THE GFS REMAINS SLIGHTLY FASTER THAN THE GFS. THE OTHER TREND OF NOTE IS THE ECMWF FURTHER NORTH WITH THE TRACK OF THE LOW PRESSURE SYSTEM. THIS COMPLICATES THE FORECAST OF PRECIP TYPE QUITE A BIT. INITIALLY WITH THE COLD SURFACE RIDGE IN PLACE WEDNESDAY...GFS FORECAST SOUNDINGS SUPPORT ALL SNOW WEDNESDAY EVENING. HOWEVER BOTH MODELS SHOW STRONG WARM AIR ADVECTION ALOFT AND A WARM NOSE DEVELOPING THROUGH THE NIGHT WITH SURFACE TEMPS REMAINING IN THE 20S AND LOWER 30S. AS THE WARM AIR ADVECTION DEVELOPS...FREEZING RAIN AND SLEET BECOME POSSIBLE WHILE SURFACE TEMPS ARE BELOW FREEZING. ON TOP OF THIS IS THE POTENTIAL FOR MID LEVEL DRY AIR TO WRAP UP IN THE SYSTEM AND FOR THE SOUNDINGS TO LOOSE SATURATION WITHIN THE DENDRITIC GROWTH LAYER ADDING TO THE POTENTIAL FOR FREEZING RAIN. REALLY THE TRACK OF THE SYSTEM DOES NOT FAVOR AN ALL SNOW EVENT FOR THE BULK OF THE FORECAST AREA. CONFIDENCE IN TRYING TO NAIL DOWN PRECIP TYPE IS VERY LOW AT THIS POINT GIVEN THAT IT IS 6 DAYS OUT...BUT THINK THAT THE PROBABILITY OF MIX WINTRY PRECIP IS HIGH ENOUGH THAT IT SHOULD BE MENTIONED IN THE FORECAST. ONE SHOULD NOT GET CAUGHT UP ON WHERE THE FORECAST HAS THE RAIN/SNOW LINE /WHICH IS LIKELY TO FLUCTUATE IN THE COMING DAYS/...BUT THAT THERE IS THE POTENTIAL FOR A MIXED BAG OF PRECIP. THINGS THAT COULD CHANGE THIS IS IF THE MAGNITUDE OF LOW LEVEL WARM AIR ADVECTION WERE TO INCREASE AND RAISE SURFACE TEMPS ABOVE FREEZING OR IF THE STORM SYSTEM TRENDS SOUTH AGAIN. IN ANY CASE IT LOOKS TO BE MESSY. WOLTERS && .AVIATION... KTOP AND KFOE WILL REMAIN UNDER VFR STRATUS AND AT TIMES MVFR STRATUS WITH OCCASIONAL LIGHT SNOW OR FLURRIES THROUGH AT LEAST 12Z. KMHK SHOULD REMAIN WEST OF THE STRATUS DECK THIS MORNING. VFR STRATUS MAY FORM AT THE TAF SITES BY AFTERNOON. GARGAN && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1127 PM CST Fri Feb 15 2013 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... Short Range (Tonight through Sunday)... Main weather concern for this period centers on the overnight period but confined to only the western third of the CWA. One last vorticity max/shortwave diving down the backside of a retreating broad upper trough will drop south-southeast across eastern NE passing just west of the MO/KS state line overnight. Satellite imagery and radar returns suggest two vorticity maxima...one moving into northeast NE and a second west of BIE. Features are best seen on NAM h7 prog. Scattered snow showers a bit more widespread than shown by NAM output while RAP looks too generous on qpf. Prefer blending the two model outputs which results in higher pops and expanding snow shield a bit more east. Moderately high liquid/snow ratios show potential for a narrow swath of 1+ inches of snow over the far western counties. Given the expected scattered coverage of the snow prefer keeping pops under the likely category for now. Snow will have exited the southwestern CWA by Saturday morning with clearing from north to south. Saturday will bring the start of a welcome warmup over the Plains which will quickly spread east...reaching into the western counties by the afternoon hours. A band of dense mid level clouds will spread from west to east Saturday night and herald the arrival of the deepening warm air advection zone. Still expecting a significant warmup on Sunday although there may be a tighter west to east gradient due as boundary layer winds take on a south-southeast direction which will limit the degree of warming further east. MJ Medium Range (Monday through Friday)... Next week continues to look very active, with two systems moving through the Plains on Monday night and again from Wednesday night through early Friday. The primary focus will be the significant system for Wednesday night through Thursday night, which has the potential to be a fairly major winter storm if the current track pans out. On Monday, a deep longwave trough will dive through the Central Plains, driving a surface cold front through the CWA during the daylight hours. A broad area of scattered rain showers will be possible along and ahead of the front, but amounts will be light as moisture return into the Plains will be quite limited. A brief mix with snow may be possible along our eastern border if any light precipitation can linger behind the surface boundary, but no snow accumulation is expected. By Wednesday night, a deep upper low will begin to eject out of the four corners region. As it moves eastward into the southern Plains, strong southerly flow will draw Gulf moisture into the system, which will combine with the existing Pacific moisture and enhance precipitation coverage and intensity as the system begins to lift northeast. All model solutions bring the elevated warm front into at least the southeastern two thirds of the CWA by Thursday morning but keep cold air lingering at the surface over almost the entirety of the area, indicating a potential for freezing rain in those areas. Since this is a deviation from previous forecasts, have started out with a slight chance for freezing rain on top of the primary rain/snow mix, but the probability for ice may need to be heightened if future forecasts look similar. As cold air wraps in behind the 850mb low, precipitation should change to all snow from west to east during the day on Thursday, becoming all snow and lifting out of the area after 00z Friday. Very preliminary snowfall totals range from more than 6 inches across the northern third of the forecast area where precipitation type is likely to be snow during the majority of the event, to 2-3 inches in west central and eastern parts of the CWA, then tapering to less than 2 inches in the far southwest where rain or freezing rain will be the predominant precipitation type during the majority of the event. With the consistency of model solutions, both temporally and between different model configurations, the overall potential for a winter storm is increasing. However, precipitation types and snowfall amounts are still somewhat uncertain and will need to be further refined, especially as this system heads onshore early next week. Laflin && .AVIATION... For the 06Z TAFs...band of light snow is rapidly weakening and pushing into west central MO, south of the KC terminals. May still see some brief light snow and MVFR restrictions lingering at MCI/MKC at the start of the TAF period but in general expect rapid improvement at these terminals soon. Behind the snow there is a lingering swath of MVFR stratocumulus over northeast KS that is skirting the STJ/MCI/MKC corridor. This may clip these terminals over the next few hours but otherwise expect no significant aviation concerns for the next 24 hours. Hawblitzel && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ WFO EAX
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
203 AM CST SAT FEB 16 2013 .UPDATE... .SHORT TERM... THE GEMREG...NAM...RUC AND HRRR SHOW A DEVELOPING WARM FRONT MOVING EAST THROUGH NRN NEB THIS MORNING AND WEAKENING DURING THE AFTN. RADAR SUPPORTS THE DEVELOPMENT OF SCATTERED SNOW SHOWERS. SKIES SHOULD CLEAR OUT BEHIND THE WARM FRONT THROUGHOUT THE MORNING...AFTN AND EVENING HOURS. TEMPERATURES TODAY RANGE FROM NEAR 40 NORTHEAST TO MID 50S SOUTHWEST. LOW THROUGHOUT THE FCST AREA TONIGHT FALL TO AROUND 20. .PREV DISCUSSION... /ISSUED 1134 PM CST FRI FEB 15 2013/ AVIATION... SHORT RANGE PROJECTIONS INDICATE LIGHT SNOW OR FLURRIES MOVING INTO NORTH CENTRAL NEBRASKA BY 12Z AND ARE MOST LIKELY NORTH AND EAST OF A VTN-BBW LINE. IN THAT AREA...CEILINGS ARE LIKELY TO BE LESS THAN 1000 FEET AGL AND VISIBILITY LESS THAN 3SM. HOWEVER...AT THIS TIME...IT APPEARS THAT VTN...TIF AND BBW WILL BE ON THE WESTERN EDGE WITH CEILINGS 1000-2000 FEET AGL AND WE WILL KEEP THE INSTRUMENT CONDITIONS OUT OF THE TERMINAL FORECAST FOR VTN FOR THE TIME BEING. IN THE REST OF CENTRAL AND WESTERN NEBRASKA...CEILINGS ARE LIKELY TO BE ABOVE 3000 FEET AGL WITH NO RESTRICTIONS TO VISIBILITY. WIND IS EXPECTED TO INCREASE SATURDAY MORNING AND BECOME 300-320 AT 10-14G20-24KT 18Z AND LATER. LOOKING AT THE SHORT TERM FORECAST SOUNDINGS FOR LBF...I SEE THAT WIND INCREASES SHARPLY AT THE TOP OF THE SURFACE INVERSION JUST ABOVE 2000 FEET AGL WITH SPEED CHANGE OF ABOUT 30KT AND ABOUT 30 DEGREES CHANGE IN DIRECTION. AT THIS TIME... IT APPEARS THAT THE SHEAR WILL BE HIGHER THAN THE THRESHOLD ALTITUDE OF 2000 FEET AGL AND WILL NOT BE INCLUDED IN THE TERMINAL FORECAST FOR LBF. THE TIME OF THE GREATEST RISK OF LOW LEVEL WIND SHEAR WILL BE 12-15Z. PREV DISCUSSION... /ISSUED 337 PM CST FRI FEB 15 2013/ SYNOPSIS... ISSUED AT 335 PM CST FRI FEB 15 2013 AT 21Z...WATER VAPOR IMAGERY SHOWED A SHORTWAVE TROUGH MOVING THROUGH THE DAKOTAS AND CENTRAL NEBRASKA EMBEDDED WITHIN A TROUGH CENTERED NORTH TO SOUTH THROUGH THE MISSISSIPPI RIVER VALLEY. UPSTREAM...A STRONG RIDGE WAS IN PLACE ACROSS THE WEST COAST...WITH A SHORTWAVE TROUGH MOVING TOWARDS BRITISH COLUMBIA. LOCALLY...CONVECTIVE SNOW SHOWERS WERE SEEN ACROSS MUCH OF NEBRASKA AS STEEP LOW LEVEL LAPSE RATES AND MIXING WAS OBSERVED. SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 335 PM CST FRI FEB 15 2013 SHOWER ACTIVITY WILL DIMINISH THIS EVENING WITH THE LOSS OF DAYTIME HEATING. CLOUD COVER WILL ALSO DIMINISH FOR A TIME DURING THE EVENING HOURS AS THE FORECAST AREA SITS IN AN AREA OF SUBISIDENCE ON THE BACKSIDE OF THE SHORTWAVE TROUGH. A WARM FRONT WILL MOVE EAST ACROSS NEBRASKA OVERNIGHT...SO EXPECTING LOWS EARLY /AROUND 06Z/. WARM ADVECTION ALOFT...ALONG WITH SOME DECENT CONVERGENT AND LIFT ALONG THE FRONT COULD BRING MORE LIGHT SNOW BEGINNING AFTER 09Z. PUT SOME FLURRIES IN THE FORECAST FOR LOCATIONS ACROSS NORTHERN NEBRASKA NEAR HIGHWAY 83. GOING INTO SATURDAY MORNING...AS THE FRONT TRANSITIONS EAST...THE SNOW CHANCES WILL ALSO MOVE EAST INTO NORTH CENTRAL NEBRASKA. DON/T BELIEVE ANY AMOUNTS WILL BE MUCH...MAYBE A TENTH OF AN INCH OR SO...BUT DID ADD SNOW CHANCES EAST OF HIGHWAY 83 AND NORTH OF HIGHWAY 91. BEHIND THE FRONT...MUCH WARMER AIR WILL MOVE INTO THE AREA. BY 00Z SUNDAY...850MB TEMPERATURES WILL RISE 10 DEGREES OR BETTER...WITH VALUES AROUND 5C OVER THE FAR SOUTHWEST COUNTIES. THIS WARMING WILL LEAD TO HIGHS IN THE 40S AND EVEN LOW 50S ACROSS THE FORECAST AREA. SNOW COVER DOES REMAIN FROM LAST WEEK/S SNOW STORM...SO WILL LIKELY SEE AN AREA WITH COOLER HIGHS FROM THE EAST CENTRAL PANHANDLE UP THROUGH NORTH CENTRAL NEBRASKA. SOME OF THESE PLACES MAY ONLY SEE HIGHS UP IN THE UPPER 30S TO AROUND 40. LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 335 PM CST FRI FEB 15 2013 A WARM FRONT WILL MOVE TO THE EAST ACROSS THE FORECAST AREA WITH WARM DRY PACIFIC AIR AS THE RIDGE OVER THE WESTERN CONUS PUSHES EAST. STILL SOME SNOW COVER OVER THE SANDHILLS BUT SATURDAYS HIGHS EXPECTED TO CUT IT BACK SIGNIFICANTLY. HIGH TEMPERATURES SUNDAY AROUND 50 SOUTH AND MID 40S NORTH. 850MB TEMPERATURES AROUND 9C SUNDAY. LOW PRESSURE WILL MOVE ALONG THE CANADIAN BORDER AND DRAW A COLD FRONT THROUGH THE NORTHERN PLAINS SUNDAY NIGHT INTO MONDAY WITH STRONG COLD AIR ADVECTION...GUSTY NORTHWEST WINDS AND POSSIBLY SOME LIGHT SNOW. HAVE LEFT DRY FOR NOW WITH BUFR SOUNDINGS SHOWING HIGH BASED PRECIP VIRGA WITH MUCH DRIER LOWER LEVELS. COLD ARCTIC AIR WILL MOVE SOUTH INTO THE CENTRAL PLAINS THROUGH THE MIDDLE OF THE WEEK WITH HIGHS IN THE 30S MONDAY FALLING INTO THE TEENS AND 20S FOR HIGHS ON THURSDAY FRIDAY. TRAJECTORY OF STORM SYSTEM MOVING OUT OF THE ROCKIES AND ONTO THE PLAINS WEDNESDAY WILL HAVE ABUNDANT MOISTURE FROM A WIDE OPEN GULF. TRAJECTORY FURTHER WEST THAN USUAL WITH MOISTURE ADVECTING ACROSS THE SOUTHERN PLAINS THROUGH THE TEXAS PANHANDLE INTO NORTHEAST COLORADO FROM WEDNESDAY. STRONG DEEP EASTERLY FLOW OVER WESTERN NEBRASKA WEDNESDAY INTO THURSDAY. HAVE UPPED POPS INTO LIKELY CATEGORIES ON THURSDAY. REMAINS TO BE SEEN HOW MUCH CONVECTION WILL BE OVER THE CENTRAL AND SOUTHERN PLAINS WHICH MAY ROB NEEDED MOISTURE. MODELS CONTINUE IN GOOD AGREEMENT WITH THIS SYSTEM. COOL DOWN TOWARDS THE END OF THE WEEK AND THEN GRADUALLY WARMING INTO THE WEEKEND BUT REMAINING WELL BELOW NORMAL FOR THE SEASON. MORE ACTIVE PATTERN. && .LBF WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...CDC LONG TERM...JACOBS AVIATION....CDC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
354 AM EST SAT FEB 16 2013 .SYNOPSIS... A STRONG TROUGH ALOFT WILL PIVOT ACROSS THE SOUTHEASTERN US TODAY...AND RESULT IN RAPID CYCLOGENESIS UP THE MIDDLE ATLANTIC AND NORTHEAST COASTS TONIGHT AND SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 340 AM SATURDAY... ...PERIOD OF WINTRY WEATHER REMAINS POSSIBLE THIS EVENING INTO TONIGHT ALONG AND EAST OF HIGHWAY 1... WILL LEAVE THE CURRENT ADVISORY AS-IS. EXPECT ACCUMULATIONS 1-2" AT MOST...AND THOSE AMOUNTS ARE MOST LIKELY IN THE NE COASTAL PLAIN NEAR THE VA BORDER N/NE OF THE TRIANGLE. ALTHOUGH IT APPEARS THAT THE SURFACE CYCLONE WILL BE DEVELOPING CLOSER TO THE COAST (NEAR MHX) THAN PREVIOUSLY ANTICIPATED AND THAT RELATIVELY MORE PRECIP WILL OCCUR ACROSS CENTRAL NC (PER LATEST RAP MODEL RUNS) IN ASSOC/W STRONG LOW-LEVEL FRONTOGENESIS 12-18Z AND THEN STRONG DPVA IN THE PRESENCE OF A DESTABILIZING AIRMASS 21-00Z...IT APPEARS THAT THE BOUNDARY LAYER WILL REMAIN TOO WARM THROUGH ~00Z THIS EVENING FOR A CHANGEOVER TO OCCUR IN MOST LOCATIONS...WITH THE COLDER AIRMASS CURRENTLY BUILDING INTO THE MID-ATLANTIC STALLING NORTH OF CENTRAL NC DUE TO VERY STRONG H5 HEIGHT FALLS IN ADVANCE OF THE APPROACHING UPPER LEVEL TROUGH...RESULTING IN BROAD PRESSURE FALLS OVER NC/VA WHICH WILL HOLD A WEAK PRESSURE TROUGH IN PLACE AND DELAY THE ARRIVAL OF THE COLDER AIRMASS FROM THE NORTH. EXPECT THE BEST CHANGEOVER POTENTIAL TO OCCUR AFTER 00Z...WHEN FORCING FOR PRECIP WILL GENERALLY BEGIN TO WANE OVER CENTRAL NC AND PRECIPITATION WILL BEGIN TO PROGRESS EAST TOWARD THE COAST. BASICALLY...THIS MAY BE YET ANOTHER CASE WHERE THE COLD AIR `CHASES` THE PRECIP...EXCEPT PERHAPS N/NE OF THE TRIANGLE WHERE FAVORABLE THERMAL PROFILES ARE MORE LIKELY TO COINCIDE WITH STRONG FORCING IN THE FORM OF LOW-LEVEL FRONTOGENESIS AND STRONG DPVA IN THE PRESENCE OF VERY STEEP (7-8C/KM) MID-LEVEL LAPSE RATES. ONE CAVEAT...GIVEN STRONG DPVA...GOOD LOW-LEVEL FRONTOGENESIS AND VERY STEEP MID-LEVEL LAPSE RATES (7-8 C/KM) IN ADVANCE OF THE APPROACHING UPPER LEVEL TROUGH...IT IS POSSIBLE THAT A QUICK BURST OF ACCUMULATING CONVECTIVE SNOW COULD OCCUR AT ABOUT THE SAME TIME AS THE COLDER AIRMASS BEGINS TO ARRIVE FROM THE NORTH ~00Z FROM GUILFORD/RANDOLPH COUNTIES EASTWARD. HOWEVER...PREVIOUS EXPERIENCE WOULD SUGGEST THAT TOO MUCH UNCERTAINTY IS PRESENT TO WARRANT EXPANDING THE ADVISORY AREA WHEN WAITING FOR A COLDER AIRMASS TO ADVECT INTO THE AREA AND WHEN RELYING PRIMARILY ON CONVECTIVE PRECIPITATION FOR ACCUMULATIONS. -VINCENT && .SHORT TERM /SUNDAY THROUGH MONDAY/... AS OF 210 AM SATURDAY... BREEZY COLD CONDITIONS EARLY SUNDAY WILL PERSIST MUCH OF THE DAY. LOW LEVEL THICKNESSES SUGGEST THE COLDEST AIR WILL BE OVER THE NORTHERN AND EASTERN ZONES WHERE HIGHS WILL STRUGGLE TO REACH NEAR 40. TEMPERATURES IN THE 40S EXPECTED ACROSS THE SOUTHERN TIER NEAR THE SC BORDER. THE COLD UPPER TROUGH IS FORECAST TO BEGIN TO LIFT OUT LATE SUNDAY INTO MONDAY. HOWEVER... THE COLD SURFACE HIGH PRESSURE IS FORECAST TO BE DIRECTLY OVERHEAD SUNDAY NIGHT INTO 12Z MONDAY. THIS WILL MEAN COLD/CLEAR/CALM CONDITIONS WITH HEAVY FROST AND HARD FREEZE BY 12Z MONDAY. LOWS 18-25. WAA WILL BEGIN MONDAY... ESPECIALLY IN THE AFTERNOON. OTHER THAN A FEW HIGH CLOUDS... IT SHOULD BE MOSTLY SUNNY WITH SW WINDS 10-15 MPH. HIGHS 48 TO 55 NE TO SW. && .LONG TERM / MONDAY NIGHT THROUGH FRIDAY/... AS OF 210 AM SATURDAY... A COUPLE OF SYSTEMS ARE EXPECTED TO BRING RAIN CHANCES TO OUR REGION THIS WEEK. THE FIRST IS FORECAST FOR TUESDAY. STRONG WARMING OUT AHEAD OF THE COLD FRONT WILL LEAD TO ALL RAIN SHOWERS. A BIT OF IN-SITU CAD MAY KEEP TEMPS DOWN IN THE PIEDMONT. QPF CONTINUES TO BE LIGHT WITH UP TO 0.25 IN THE NW WITH LESSER AMOUNTS TO THE EAST. CLOUDY WITH A 40-50 PERCENT CHANCE OF SHOWERS. HIGHS GENERALLY IN THE 45-50 RANGE NW... WITH 50S SE AFTER LOWS OF 35-42 TUESDAY. WEDNESDAY AND THURSDAY... HIGH PRESSURE SHOULD BUILD IN FROM THE NW AND NORTH WED-THU... WITH THE STRONGEST CAA EXPECTED THU. THIS MAY SET UP A STRONGER CAD EVENT FOR FRIDAY AS THE HIGH IS FORECAST TO BE IN A FAVORABLE POSITION AND STRENGTH TO INDUCE CAD AS THE NEXT SYSTEM APPROACHES FRIDAY. WED...FAIR AND SEASONABLE. LOWS IN THE 30S. HIGHS IN THE 50S. THU... MOSTLY SUNNY. LOWS 25-30. HIGHS 48-53. FRI..MOSTLY CLOUDY. A CHANCE OF RAIN. CHILLY. LOWS IN THE 30S. HIGHS IN THE 40S EXCEPT 50-55 SE. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 100 AM SATURDAY... AFTER INITIALLY VFR CONDITIONS...THE PASSAGE OF A STRONG DEEP LAYER FRONTAL ZONE WILL RESULT IN A RAPIDLY EXPANDING...BUT NARROW... PRECIPITATION AXIS ACROSS THE WEST-CENTRAL CAROLINAS BETWEEN 09-15Z. THE PRECIPITATION AXIS WILL THEN EXPAND IN AREAL EXTENT AND PIVOT EASTWARD ACROSS CENTRAL NC THROUGH THIS EVENING...OWING TO THE AMPLIFICATION OF A STRONG TROUGH ALOFT FROM THE CENTRAL PLAINS TO THE SOUTHEAST STATES. THE PRECIPITATION WILL LIKELY BEGIN AS A MIX OF RAIN AND SNOW...BEFORE GRADUALLY TRANSITIONING TO ALL SNOW FOR THE AFTERNOON AND EVENING HOURS. CEILINGS AND VISIBILITY RESTRICTIONS WILL CONSEQUENTLY FALL INTO MVFR-IFR RANGE...BEFORE THE STEADY PRECIPITATION ENDS AND SKIES CLEAR FROM WEST TO EAST THIS EVENING. A FEW LINGERING SNOW SHOWERS WILL BE POSSIBLE THROUGH MIDNIGHT...HOWEVER...AS THE VERY COLD AND DYNAMIC TROUGH AXIS ALOFT PIVOTS EASTWARD. LOOKING AHEAD: BREEZY CONDITIONS SUNDAY...FOLLOWED BY ANOTHER FRONTAL SYSTEM AND ASSOCIATED SUB-VFR CONDITIONS AND RAIN THAT WILL AFFECT THE REGION TUE. && RAH WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 4 PM SATURDAY TO 4 AM EST SUNDAY FOR NCZ007>011-025>028-041>043-077-078-085-086-088-089. && $$ SYNOPSIS...MWS NEAR TERM...VINCENT SHORT TERM...BADGETT LONG TERM...BADGETT AVIATION...MWS
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
414 AM EST SAT FEB 16 2013 .SYNOPSIS... A MOIST UPPER LEVEL LOW WILL CROSS THE REGION TODAY...WITH DRY HIGH PRESSURE BUILDING IN FROM THE NORTH SUNDAY. A COLD FRONT WILL APPROACH THE CAROLINAS AND NORTHEAST GEORGIA TUESDAY WITH ANOTHER AREA OF CANADIAN HIGH PRESSURE BUILDING IN ON WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF EARLY SAT MORNING...UPPER TROUGH WILL SWING THROUGH THE REGION TODAY WITH FURTHER COLD ADVECTION AND STRONG VORT MAX ACCOMPANYING IT. VERY LIGHT PRECIP ALREADY FALLING OVER THE PIEDMONT. THIS AREA IS FAVORED BY THE NAM...GFS...RAP AND HRRR AS BEING THE FOCUS FOR THE BULK OF THE PRECIP. FORCING FROM THE WAVE WILL BE ENHANCED OVER THE PIEDMONT BY LOW LEVEL CONVERGENCE BETWEEN THE INVADING ARCTIC AIRMASS AND EXISTING COASTAL AIR. THE TROUGH STEADILY PROGRESSES EAST...WITH THE BASE HAVING DEPARTED THE CWFA BY 00Z...WITH DEEP DRY AIR RAPIDLY WORKING IN. TEMPERATURE PROFILES DO NOT INDICATE A WARM NOSE GIVEN THE ALREADY COLD AIR IN PLACE. DEEP SATURATION MEANS RAIN OR SNOW WILL MAINLY BE DETERMINED BY SURFACE TEMP. FREEZING LEVELS ARE PRETTY LOW AND SFC TEMPS WILL BE MOSTLY IN THE 30S OVER THE PIEDMONT. A RAIN/SNOW MIX WILL LIKELY TRANSITION TO SNOW AS THE FREEZING LEVEL LOWERS DUE TO THE WET BULB EFFECT. FOR QPF...SOMEWHAT TRICKY WITH OPERATIONAL MODELS SHOWING SOME POSSIBLE CONVECTIVE EFFECTS AND LOCALIZED AREAS SEEING SIGNIFICANTLY HIGHER AMOUNTS OF SNOWFALL. INDEED BOTH THE NAM AND GFS SHOW UP TO A COUPLE HUNDRED JOULES OF MUCAPE THIS AFTERNOON OVER A PORTION OF NE GA AND THE WESTERN UPSTATE. 21Z SREF BACKS THIS UP WITH LIKELY-RANGE PROBS OF 100 J. SO THIS COULD HELP ENHANCE TOTALS DURING THE EARLY TO MID AFTERNOON WHEN THE FORCING IS STRONGEST ANYWAY. CHOSE MODEST QPF DERIVED FROM A MODEL BLEND WHICH HAPPENS TO BE IN LINE WITH THE GENERAL PATTERN AND AMOUNTS OF THE LAST FEW GFS RUNS...WITH ABOUT A QUARTER INCH SOUTHEAST OF A LINE FROM GREENWOOD TO CHESTER. FAIRLY HIGH SNOW RATIOS OF 13-16 TO 1 WILL PRODUCE TOTALS GENERALLY OF 1 TO 2 INCHES TODAY. THIS MEETS OUR WINTER WX ADVY CRITERIA OVER THE SRN FOOTHILLS AND PIEDMONT OF NC AS WELL AS MOST OF THE SC PIEDMONT. IN ADDITION TO THE SYNOPTIC FORCING...PERSISTENT NORTHWEST FLOW WILL PRODUCE ENHANCED SNOWFALL IN THE UPSLOPE AREAS OF THE MOUNTAINS. NONETHELESS...TOTALS ARE COMPARABLE TO PREVIOUS FCST AND EXISTING WINTER WX ADVY WILL COVER THIS. HIGH TEMPS TODAY WILL BE WELL BELOW NORMAL IN THE ARCTIC AIR. WITH MOSTLY OVERCAST SKIES USED A BLEND OF GFS AND CMC-REGIONAL TEMPS. BOTH THE GFS AND NAM QUICKLY DRY THINGS OUT BEHIND THE DEPARTING TROUGH SO SOME BREAKS IN THE CLOUD COVER COULD COME LATE IN THE DAY ESPECIALLY SOUTHWEST...BUT PROBABLY TOO LATE TO HAVE MUCH OF AN IMPACT ON HIGHS. FURTHERMORE ANY SNOW COVER COULD LIMIT TEMPS FROM RISING. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... AS OF 300 AM SATURDAY...THE UPPER TROUGH AXIS WILL PROGRESS QUICKLY ACROSS THE REGION TONIGHT...BRINGING A QUICK END TO ANY LINGERING PRECIP. THE ONLY EXCEPTION WILL BE ACROSS THE FAR WESTERN NC MTNS... AS A MOIST NW FLOW SHOULD YIELD PERSISTENT SNOW SHOWERS THROUGH THE OVERNIGHT. THE MODELS ARE RATHER STINGY WITH QPF TONIGHT...AS THE NAM BARELY SQUEEZES OUT .05-.1 INCH ALONG THE TENN BORDER...WHILE THE GFS IS EVEN DRIER. THIS IS SOMEWHAT SURPRISING...AS THE MOIST LAYER IS PROGGED TO EXTEND TO ABOUT 800 MB THROUGH THE OVERNIGHT... WHILE H8 WINDS SHOULD BE IN THE 30-40 KT RANGE. IN ADDITION...TEMPS IN THE MOIST LAYER ARE EXPECTED TO BE EXTREMELY COOL...AS LOW AS -19 C BY 12Z SUNDAY. THEREFORE...EVEN IF THERE IS LITTLE LIQUID EQUIVALENT...THIS PATTERN IS SUGGESTIVE OF EFFICIENT SNOW PRODUCTION...WITH SNOW:LIQUID RATIOS AS HIGH AS 30:1 POSSIBLE LATE TONIGHT. THEREFORE...WE WILL FORECAST AN ADDITIONAL 1 TO 4 INCHES IN THE USUAL NW FLOW AREAS OVERNIGHT. TEMPS WILL BE VERY COOL TONIGHT THROUGH TOMORROW...EASILY 10 DEGREES BELOW CLIMO. HOWEVER...WITH HEIGHTS RISING IN THE WAKE OF THE UPPER TROUGH AXIS...THE REMAINDER OF THE SHORT TERM WILL FEATURE QUICKLY MODERATING TEMPS THAT WILL WARM VERY CLOSE TO NORMAL BY MONDAY AFTERNOON. BY THE END OF THE PERIOD...A MAJOR STORM SYSTEM WILL LIFT OUT OF THE CENTRAL PLAINS...WITH AN ATTENDANT FRONTAL BAND OF PRECIP EXPECTED TO MARCH ACROSS THE TENN VALLEY LATE MONDAY/MONDAY NIGHT. POPS WILL INCREASE QUICKLY FROM WEST TO EAST ACROSS OUR AREA LATE MONDAY NIGHT...BECOMING LIKELY ACROSS THE NC MTNS BY DAYBREAK. IT STILL APPEARS THAT PRECIP COULD BEGIN AS SNOW IN THE HIGH ELEVATIONS OF THE NC MTNS. THERE COULD ALSO BE SOME BRIEF FREEZING RAIN IN SHELTERED VALLEYS TUE MORNING...BUT THE PREDOMINANT P-TYPE SHOULD BE RAIN IN ALL AREAS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 330 AM SATURDAY...THE COLD FRONT WILL STILL BE OFF TO THE WEST BY 12Z TUE WITH A DECENT SPREAD OF LIGHT PRECIP ACROSS MOST OF THE CWFA...INCREASING EAST THROUGHOUT THE DAY. THE STRONGEST QG FORCING WILL REMAIN NORTH DURING FROPA...HOWEVER A 100 KT FINGER OF THE STJ WILL PUSH INTO MIDLANDS AND PROVIDE SOME MEASURE OF UPPER DIV SUPPORT OVER THE SRN MOST ZONES. THE FLOW BACKS DOWN THE PROFILE AND THE LLVL JET BECOMES ALIGNED PARALLEL TO THE BLUE RIDGE...THUS MECHANICAL LIFT WILL BE LIMITED. ALL THIS TO SAY THE ADDITIONAL PRECIP AMOUNTS UNTIL FROPA EARLY WED WILL BE RATHER LIGHT WITH MOST AREAS RECEIVING LESS THAN A QUARTER INCH. THERE COULD BE SOME WRAP AROUND -SNSH LINGERING ACROSS THE NRN MTNS THROUGH 06Z WED...BUT THE TREND HAS BEEN FOR LESS AND LESS AVAILABLE MOISTURE...ESP WITH THE ECMWF. IN ANY CASE...ANY AMOUNTS OF SNOW WILL BE LIGHT BTW 00Z-06Z WED. HIGH TEMPS WILL BE TRICKY WITH ALL THE CLOUDS/PRECIP...YET DECENT SW/LY FLOW...BUT MAXES A CAT OR SO BELOW NORMAL SEEMS REASONABLE PER THE LLVL THICKNESS PATTERN AND SUFFICIENT LACK OF INSOL. THE MODELS AGREE WELL WITH THE PATTERN WED THROUGH THE END OF THE PERIOD. A SHARP RIDGE AXIS WILL BUILD ACROSS THE PLAINS STATES AND PROPAGATE TOWARD THE EAST COAST THROUGH 00Z FRI. THIS WILL MAINTAIN CANADIAN HIGH PRESSURE AT THE SFC AND LOW BL THETA/E AIR WED AND THU. GOOD INSOL...BUT N/LY FLOW WILL KEEP MAXES NEAR NORMAL PERHAPS A DEGREE OR SO BELOW WED. A MODIFYING AIRMASS WITH INCREASING MID/HIGH CLOUDS THU SHOULD HOLD MAX TEMPS IN CHECK AT ABOUT 3-4 DEGREES BELOW NORMAL. ANOTHER LOW PRESSURE SYSTEM DEEPENS AND MOVES INTO THE CENTRAL MIDWEST BY THU EVENING. THE BEST UPPER DYNAMICS AGAIN WILL BE WELL NORTH OF THE CWFA BY THE TIME A COLD FRONT REACHES THE NC MTNS AROUND MID DAY FRI. THE MAIN PRECIP TYPE LOOKS TO BE ALL RAIN...WITH SOME HIGH ELEV SNOW. AGAIN...AMOUNTS LOOK TO REMAIN ON THE LOW SIDE. THERE COULD BE A DEVELOPING TRIPLE POINT LOW AND A MEASURE OF SFC/BASED SHEAR STORM DEVELOPMENT FRI AFTERNOON...BUT INSTABILITY BE A LIMITING FACTOR FOR ANY REAL STRONG/SVR CONCERN OR CONJECTURE AT THIS POINT. THE CWFA WILL LIKELY SEE A NOTICEABLE GRADIENT OF MAX TEMPS FRI AS THE LLVL THERMAL TROF EXITS TO THE NORTH AND A WARM FRONT IMPINGES UPON THE AREA FROM THE SOUTH. FOR NOW...GENERALLY THINK MAX TEMPS WILL BE A 3-5 DEGREES ABOVE NORMAL SOUTH AND ABOUT 5-8 DEGREES BELOW NORMAL NORTH OF I40. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/... AT KCLT...VFR CIG WITH UNLIMITED VSBY EXPECTED TO PERSIST FOR MUCH OF THE NIGHT. NAM AND GFS GUIDANCE BOTH INDICATIVE OF PRECIP DEVELOPING OVER THE NC PIEDMONT JUST BEFORE DAYBREAK IN AREA OF LLVL CONVERGENCE ASSOCIATED WITH FURTHER PUSH OF COLD AIR. GFS AND ITS DERIVATIVES BRING THIS IN WITHOUT RESTRICTIONS WHILE THE NAM FAMILY SHOWS LOW MVFR TO IFR CIGS. CAN/T TOTALLY DISREGARD THIS THOUGH THE FORCING IS NOT IDEAL AND BOTH MODELS ARE OVERDOING PRECIP ATTM. LOWERING CIG LIKELY THROUGH THE MORNING SO TO HANDLE THE POTENTIAL JUST MOVED THE MVFR UP TO 11Z. 00Z MODEL PACKAGE STILL SUPPORTIVE OF A MIDDAY PEAK IN PRECIP ACTIVITY AHEAD OF UPPER TROUGH PASSAGE. SFC TEMPS MAY BE ABOVE FREEZING THOUGH SNOW WOULD STILL BE ABLE TO REACH THE SFC...IF NOT SNOW THEN RAIN. CIGS LIFT TO VFR BY AFTERNOON THEN SCATTER AFTER 00Z SUN. NW WINDS THRU THE PERIOD. BIGGEST GUST POTENTIAL IS IN THE EVENING WITH INCREASING COLD AIR ADVECTION PROMOTING MIXING. ELSEWHERE...MOSTLY VFR CIGS TONIGHT WITH NO VSBY RESTRICTIONS ANTICIPATED. GUIDANCE INDICATES SOME POSSIBILITY OF MVFR CIG DEVELOPING WITH PRECIP JUST BEFORE DAYBREAK OVER THE ERN PIEDMONT THOUGH CONFIDENCE IS LOW THAT THAT WOULD HAPPEN. CIGS HOWEVER LIKELY TO LOWER WITH INCREASING DEEP MOISTURE BY THE EARLY DAYTIME HOURS. MVFR CIGS WILL ACCOMPANY PRECIP IN THE LATE MORNING WEST TO MIDDAY EAST. PRECIP TYPE WILL SOMEWHAT DEPEND ON SFC TEMP THOUGH SNOW SHOULD BE ABLE TO AT LEAST MIX IN AT ALL THE SITES. CHC TOO LOW TO MENTION AT KAND BUT IS INCLUDED ELSEWHERE. RETURN TO VFR BY LATE AFTN WITH GUSTS POSSIBLE FROM MIDDAY THROUGH THE END OF THE PERIOD AS COLD ADVECTION MAINTAINS DEEPLY MIXED SFC LAYER. OUTLOOK...MOISTURE AND SOME RESTRICTIONS WILL REMAIN ALONG THE TN BORDER THROUGH EARLY SUNDAY. ELSEWHERE...CONDITIONS WILL GENERALLY REMAIN DRY WITH VFR CONDITIONS. HIGH PRESSURE BUILDS OVER THE REGION EARLY NEXT WEEK. CONFIDENCE TABLE... 09-15Z 15-21Z 21-03Z 03-09Z KCLT HIGH 94% MED 75% HIGH 95% HIGH 100% KGSP HIGH 91% LOW 55% HIGH 100% HIGH 100% KAVL HIGH 98% MED 77% HIGH 100% HIGH 100% KHKY HIGH 97% MED 76% HIGH 100% HIGH 100% KGMU HIGH 94% LOW 54% HIGH 100% HIGH 100% KAND HIGH 91% LOW 53% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .FIRE WEATHER... DRY AND BREEZY TO WINDY CONDITIONS ARE EXPECTED ON SUNDAY. HOWEVER...THE LOWEST RH VALUES WILL BE MID TO LATE AFTERNOON...WHILE THE WINDIEST CONDITIONS SHOULD BE IN THE MORNING THROUGH EARLY AFTERNOON. IN ADDITION...WE WILL HAVE TO WAIT AND SEE HOW MUCH PRECIPITATION FALLS OVER THE NEXT 24 TO 36 HOURS IN ORDER TO ASSESS FUEL MOISTURE CONTENT AND ASSOCIATED FIRE DANGER FOR LATE THIS WEEKEND. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...WINTER WEATHER ADVISORY UNTIL NOON EST SUNDAY FOR NCZ033- 048>052-058. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NCZ053- 065-068>072-082-501-503-505-507>510. SC...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR SCZ002- 003-005>009-012>014. && $$ SYNOPSIS...SBK NEAR TERM...WIMBERLEY SHORT TERM...JDL LONG TERM...SBK AVIATION...WIMBERLEY FIRE WEATHER...GSP
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1139 PM EST FRI FEB 15 2013 .SYNOPSIS... A COLD FRONT MOVES EAST OF THE REGION OVERNIGHT...FOLLOWED BY A STRONGER ARCTIC COLD FRONT SATURDAY NIGHT. MEANWHILE...AN AREA OF LOW PRESSURE WILL FORM ALONG THE FIRST BOUNDARY AND MOVE OFF THE CAROLINA COAST BEFORE TURNING NORTH LATER SATURDAY. HIGH PRESSURE ARRIVES SUNDAY NIGHT BEFORE ANOTHER COLD FRONT ENTERS THE APPALACHIANS LATE MONDAY NIGHT. && .NEAR TERM /THROUGH SATURDAY/... AS OF 950 PM EST FRIDAY... BASED ON ADDED SNOWFALL REPORTS OF AROUND 3 INCHES IN TAZEWELL CTY ALONG WITH DEVELOPING SLICK ROAD CONDITIONS...WENT AHEAD WITH A WINTER WEATHER ADVISORY THROUGH 4 AM FOR TAZEWELL...MERCER AND BLAND CTYS WHERE COULD SEE UP TO 4 INCHES OF SNOW BEFORE THINGS TAPER OFF TO FLURRIES. AS OF 845 PM EST FRIDAY... PERSISTENT BAND OF SNOW REMAINS ACROSS FAR SW VA INTO SE WVA ALONG THE LEADING EDGE OF THE DEEPENING 5H TROF TO THE WEST AND UNDER A WEAK SHORTWAVE AHEAD OF THE MAIN UPPER COLD POOL. WARM SURFACES FROM EARLIER TODAY HAVE APPARENTLY LIMITED ACCUMULATIONS DESPITE SEVERAL HOURS OF DECENT SNOWFALL WITH TOTALS OF 1-2 INCHES REPORTED MAINLY ON GRASSY SURFACES. SINCE APPEARS WILL BE TAPERING SHORTLY WONT HOIST AN ADVISORY YET UNLESS HEAVIER BANDS PERSIST LONGER. OTRW LATEST RAP AND LOCAL RNK WRF SHOW THIS BAND OF SNOW FINALLY WEAKENING BEFORE MIDNIGHT AS ENERGY SHIFTS EAST AND THE 85H FLOW TURNS MORE NNW. THUS KEEPING IN A FEW MORE HOURS OF CAT/LIKELY POPS THERE BEFORE DIMINISHING AFTER MIDNIGHT. OTRW COLD FRONT NOW ENTERING THE PIEDMONT WITH A FEW RAIN SHOWER BANDS ALONG IT OVER THE SE IN STRONG SW FLOW ALOFT DEPICTED OFF EVENING SOUNDINGS. EXPECT THIS RAINFALL TO AFFECT AREAS MAINLY EAST OF THE BLUE RIDGE BEFORE THE FRONT FINALLY GETS FAR ENOUGH EAST OF THE REGION TO SUPPORT A LITTLE BETTER DOWNSLOPING IN THE NEXT FEW HOURS. THUS THINKING WILL SEE A LULL IN PRECIP FOR THE MOST PART DURING THE EARLY MORNING HOURS WITH THE FRONT TO THE SE...ONLY WEAK UPSLOPE OVER THE WEST...AND LITTLE SUPPORT ALOFT AS WE SLIDE IN BETWEEN UPPER IMPULSES LATER TONIGHT. THIS IN LINE WITH POPS FROM EARLIER FOR AFTER MIDNIGHT SO ONLY TWEAKED POP COVERAGE LATER ON. HAVE SEEN LITTLE SNOW IN THE ADVISORY AREA BUT LEAVING HEADLINES AS IS FOR NOW. TEMPS SLOW TO FALL OUT EAST BUT WILL GET INTO BETTER COLD ADVECTION SHORTLY WITH THE LAV MOS LOOKING TOO WARM MOST SPOTS OVERNIGHT. PREVIOUS DISCUSSION... A MORE POTENT UPPER LEVEL WAVE PUSHING INTO THE CENTRAL PLAINS THIS AFTERNOON WILL MOVE ACROSS THE CAROLINAS ON SATURDAY...WHICH SPINS UP A SFC LOW OFF THE NC COAST. MODELS SHOW GOOD 700MB FRONTOGENESIS FORMING IN ADVANCE OF THIS SYSTEM...SUGGESTING HEAVY BANDS OF PRECIP WILL DEVELOP ACROSS NC AND IN THE EASTERN PORTION OF OUR FORECAST AREA. FORECAST SOUNDINGS SUGGEST TEMPS ALOFT WILL SUPPORT SNOW...OR A RAIN/SNOW MIX. DYNAMIC COOLING WITH THIS STRONG SYSTEM SHOULD KEEP MOST OF THE PRECIP IN THE FORM OF SNOW. SOME FACTORS THAT COULD LIMIT SNOW ACCUMULATION ARE THE WARM GROUND TEMPS AND THE FACT OUR AREA WILL BE ON THE NORTHWEST SIDE OF THE BEST LIFT. IN FACT...THE GFS IS AN OUTLIER WITH THE WESTERN EXTENT OF THE PRCIP SHIELD...AND A SLIGHTLY MORE EASTERN TRACK...AS SHOWN BY THE 12Z ECMWF KEEPS THE HEAVIEST AMOUNTS OUT OF FORECAST AREA. STILL...WILL ISSUE WINTER WEATHER ADVISORIES FOR THE NC MOUNTAINS FOR NEAR ADVISORY CRITERIA IN HIGHER ELEVATIONS...BUT LESS AMOUNTS TO THE EAST AND NO HEADLINES. AS THE SFC LOW DEEPENS...WINDS WILL INCREASE FROM THE NORTHWEST AND UPSLOPE SNOW SHOWERS WILL AGAIN DEVELOP ACROSS SOUTHEAST WEST VIRGINIA. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... AS OF 408 PM EST FRIDAY... LOW PRESSURE MOVING ALONG TONIGHT`S COLD FRONT SATURDAY WILL BE MOVING FAR ENOUGH AWAY FROM OUR AREA TO PULL ITS PRECIP SHIELD JUST OUT OF OUR EXTREME EASTERN COUNTIES EARLY SATURDAY NIGHT. DEPENDING UPON HOW DEEP THIS LOW TURNS OUT TO BE...SNOW MAY HOLD ALONG THESE COUNTIES A LITTLE LONGER THAN CURRENTLY FORECAST. ARCTIC BOUNDARY ARRIVING WILL GENERATE UPSLOPE SNOW SHOWERS AGAIN SATURDAY NIGHT...WITH ENOUGH MOISTURE TO POSSIBLY DELIVER SOME SNOW SHOWERS INTO THE NEW RIVER VALLEY. AS AN UPPER LEVEL DISTURBANCE LEAVES AFTER MIDNIGHT INTO SUNDAY MORNING...MOISTURE DRIES OUT RAPIDLY AND SNOW SHOWERS WILL BE MORE CONFINED TO SE WEST VA. EXPECTING THE GREATEST COVERAGE OF SNOW SHOWERS AROUND 6Z/1AM SUNDAY. UP TO 4" MAY FALL ACROSS WESTERN GREENBRIER WITH AN INCH OR TWO DOWN INTO BLF AND SIMILAR LOCATIONS ABOVE 2500 FEET. WIND DIRECTION SHOULD ALSO DELIVER SOME SNOW BANDS INTO NW NC WHERE AN INCH OR LESS IS EXPECTED BUT 2" ABOVE 3500 FEET. AS CLOUDS ARE REMOVED AND BETTER MIXING OCCURS ADVISORY CRITERIA WIND GUSTS ARE LIKELY ASHE/WATAUGA/GRAYSON AND A HIGH WIND WATCH MAY NEED TO BE CONSIDERED. AGAIN...MOS TEMPS LOOK TOO WARM WITH A SHALLOW ARCTIC AIRMASS SO USED SOME OF THE COLDER VALUES. SINGLE DIGITS DEWPOINTS AND RELAXING OF WIND WILL ALLOW DECOUPLING AND WIDESPREAD LOWS IN THE MIDDLE TEENS SUNDAY NIGHT. UPPER TROUGH LEAVES MONDAY WITH QUICK WAA...BUT A LOW MOVING INTO THE GREAT LAKES WILL DRAG A FRONT AND PRECIP ACROSS THE REGION LATE MONDAY NIGHT...WITH EVAP COOLING LIKELY PRODUCING A QUICK SHOT OF SLEET AND MAYBE SOME FREEZING RAIN ACROSS GREENBRIER INITIALLY. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 350 PM EST FRIDAY... HIGH PRESSURE DRIFTS OFF THE SOUTHEAST COAST ALLOWING A COLD FRONT TO PASS OVER THE REGION TUESDAY. A WINTRY MIX OF RAIN/SNOW/SLEET MAY STILL BE FALLING ACROSS THE GREENBRIER VALLEY AND ALLEGHANY HIGHLANDS TUESDAY MORNING. TEMPERATURES WARM BY MID MORNING WITH ALL PRECIPITATION FALLING AS RAIN. RAIN EXITS QUICKLY BY THE EVENING RUSH HOUR WITH WINDS INCREASING FROM THE WEST. WE WILL SEE CLEARING CONDITIONS FROM EAST TO WEST OVERNIGHT WITH SOME LINGERING CLOUDS/UPSLOPE SNOW SHOWERS INTO EARLY WEDNESDAY MORNING. TRAJECTORIES ARE NOT FAVORABLE FOR SIGNIFICANT UPSLOPE ACCUMULATIONS. MOISTURE COULD BE SHALLOW BY THE TIME THE COLDEST AIR ARRIVES TO JUST HAVE SPOTTY FREEZING DRIZZLE/SCATTERED FLURRIES. STRONG SOUTHWEST FLOW AHEAD OF THE FRONT MAY CREATE SOME WIND PROBLEMS ACROSS THE BLUEFIELD/RICHLANDS AREA TUESDAY MORNING. AS THE JET TRANSFERS EAST OF THE APPALACHIANS...STRONG WINDS MIXING TO THE SURFACE COULD PRODUCE ADVISORY GUSTS FOR THE REST OF THE AREA. WILL CONTINUE TO HIGHLIGHT IN THE HWO. STRONG AND GUSTY WINDS WILL ALSO FOLLOW THE FRONT WITH ANY ADVISORY GUSTS REMAINING ALONG THE HIGHER RIDGES ALONG THE BLUE RIDGE. HIGH PRESSURE WILL MOVE OVER THE REGION WEDNESDAY AFTERNOON WITH BREEZY CONDITIONS RELAXING BY THE EVENING. A WARM FRONT IS EXPECTED TO OVERRUN THIS SURFACE HIGH PRESSURE ON THURSDAY. LIGHT PRECIPITATION COULD START FALLING AS EARLY AS THURSDAY AFTERNOON (12Z GFS) OR START EARLY FRIDAY MORNING (12Z ECMWF). AS PRECIPITATION FALLS INTO THIS RIDGE...AN INSITU WEDGE WILL DEVELOP WITH A PERSISTENT EASTERLY FLOW THROUGH THE DAY FRIDAY. DESPITE THE TIMING DIFFERENCES...EVAPORATIVE COOLING IN BOTH MODELS OVERNIGHT SUPPORT FROZEN PRECIPITATION THURSDAY NIGHT INTO FRIDAY. GFS FORECAST SOUNDING SUGGESTING FREEZING RAIN. WITH UNCERTAINTY LOOMING LARGE THIS FAR OUT...WILL KEEP GRIDS SIMPLE WITH RAIN/SNOW. GFS IS ALSO BREAKING THE WEDGE QUICKLY FRIDAY MORNING. KEPT THE WEDGE IN LONGER AND COULD SEE IT BREAKING FRIDAY NIGHT VIA PRESSURE FALLS OVER THE OHIO VALLEY PER THE ECMWF. TEMPERATURES WILL HOVER AROUND NORMAL ON TUESDAY. CHILLY HIGH PRESSURE WILL TREND AFTERNOON TEMPERATURES BELOW NORMAL WEDNESDAY AND THURSDAY. TEMPERATURES WILL CONTINUE TO TREND COLDER FRIDAY WITH A WET COLD AIR DAMMING EVENT EXPECTED. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 1130 PM EST FRIDAY... COLD FRONT NOW CROSSING INTO THE PIEDMONT WITH A LINGERING BAND OF MOSTLY RAIN SHOWERS ALONG AND BEHIND THE BOUNDARY MAINLY FROM KLYH TO KMTV ATTM. LOCAL WRF CONTINUES TO STILL HAVE THE BEST HANDLE SO WILL FOLLOW CLOSELY AND PUSH RAIN A BIT FARTHER EAST INTO KLYH/KDAN FOR A FEW HOURS OVERNIGHT SINCE GOOD DOWNSLOPE IS LAGGING THE FRONT. OTRW WILL HAVE PERIODIC MVFR TO IFR AT KBLF WHERE SNOW HAS FINALLY TAPERED OFF...AND MOSTLY MVFR AT KLWB/KBCB AS EXPECTING UPSLOPE TO KEEP LOW CIGS ALONG THE WESTERN SLOPES WITH SOME OF THE COLD ADVECTION STRATO-CU SPILLING EAST TOWARD THE BLUE RIDGE OVERNIGHT. MAY CONTINUE TO INCLUDE A VFR MENTION OF A -SHSN OVERNIGHT IN THE WEST BUT LOOKING QUITE ISOLATED UNTIL LATE AT BEST WHEN BETTER UPSLOPE KICKS IN. ELSW WILL MAINTAIN VFR OUT EAST PENDING JUST HOW FAR THE PRECIP GETS IN THE NEXT FEW HOURS BUT EVEN THEN APPEARS CIGS AOA 4K FT. KLWB AND KBLF WILL TRANSITION TO AN UPSLOPING PCPN -SHSN EVENT BY DAYBREAK AND CONTINUE OFF AND ON THROUGH SATURDAY. STILL LOOKING FOR MVFR CIGS/VSBYS AND EXPECT -SHSN TO BE LIGHT AS BEST MOISTURE WILL BE TO THE EAST WITH THE OFFSHORE LOW TAKING SHAPE. KDAN/KLYH IS INTERESTING FOR THE LATTER PORTION OF THE TAF PERIOD. LIFT DEVELOPING ON THE BACK SIDE OF THE DEEPENING LOW SLIDING OFF THE COAST WILL BEGIN TO DEVELOP A PRECIPITATION SHIELD TO THE WEST. IT CURRENTLY LOOKS LIKE KDAN WILL BE ON THE EDGE OF THIS AND WILL INTRO A PERIOD OF MVFR CIGS IN AFTER 12Z ALONG WITH SOME PCPN THAT MAY BE ALL SNOW DURING THE MORNING. ALSO POTENTIAL FOR A NARROW RIBBON OF SNOW OR SNOW SHOWERS TO DEVELOP NEAR HIGHWAY 29 SATURDAY AFTERNOON WHICH COULD BRING LOCALIZED MVFR/IFR IN A SWATH SO INCLUDING A BIT MORE SNOW MENTION AT BOTH KDAN/KLYH AGAIN SATURDAY AFTERNOON BUT LOW CONFIDENCE AT THIS POINT. LOW LEVEL WINDS DO NOT RAMP UP UNTIL LATER IN THE DAY SATURDAY IN RESPONSE TO DEEPENING OF COASTAL LOW SO DO NOT EXPECT SIGNIFICANT WINDS TO HAMPER AVIATION INTERESTS UNTIL LATE SATURDAY OR MORESO SATURDAY NIGHT. EXTENDED AVIATION DISCUSSION... REASONING THROUGH THE EXTENDED PORTION STILL APPLIES AS PER PREVIOUS DISCUSSION: HIGH PRESSURE AND VFR CONDITIONS WILL RETURN TO THE MOUNTAINS BY SUNDAY ALTHOUGH NW WINDS WILL BE QUITE STRONG AND GUSTY. GOOD FLYING WEATHER SHOULD PREVAIL UNTIL TUESDAY...WHEN A NEW COLD FRONT COULD BRING SHOWERS WITH GUSTY WINDS ALONG WITH MVFR/IFR CEILINGS. VFR QUICKLY RETURNS ON WEDNESDAY WITH HIGH PRESSURE FOLLOWING THE FRONT. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WINTER WEATHER ADVISORY UNTIL 4 AM EST SATURDAY FOR VAZ007-010. NC...WINTER WEATHER ADVISORY UNTIL NOON EST SUNDAY FOR NCZ001-018. WV...WINTER WEATHER ADVISORY UNTIL 4 AM EST SATURDAY FOR WVZ042. && $$ SYNOPSIS...AMS/KM NEAR TERM...AMS/JH/PH SHORT TERM...KM LONG TERM...RCS AVIATION...AMS/JH/NF
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1048 PM CST FRI FEB 15 2013 .SHORT TERM...THROUGH MONDAY NIGHT 319 PM CST FRI FEB 15 2013 BENIGN WEATHER THROUGH THE WEEKEND LEADS INTO MONDAYS WEATHER SYSTEM WHICH WILL NEED TO BE WATCHED FOR CHANGES. MUCH LESS CLOUD ACROSS THE AREA TODAY THAN FORECAST WITH MIXING NOT DEEP ENOUGH TO FORM MUCH STRATOCUMULUS EXCEPT OVER NORTH-CENTRAL WI. LONGWAVE TROUGH AXIS CONTINUES EASTWARD PROGRESS WITH LAST OF SHORTWAVE TROUGH ENERGY COMING THROUGH TONIGHT AND EARLY SATURDAY. LATEST RAP AND WATER VAPOR HAS THIS BROAD CIRCULATION AXIS FROM KINL-KLBF...AND SURFACE LOW PRESSURE IN EASTERN NEB. CLOUD COVER OVER NWRN MN MOVING TOWARD THE AREA WILL ARRIVE THIS EVENING FOR A CLOUD PERIOD INTO SATURDAY MORNING. NOT TO CONFIDENT ON THE COVERAGE OF THIS CLOUD COMING IN...IT MAY BE MORE IN AREAS. HAVE LEFT A MENTION OF FLURRIES IN THIS WEAKLY LIFTED AIR MASS THROUGH NOON SATURDAY. AGGRESSIVE RIDGE BUILDING THEN TAKES PLACE LATER SATURDAY AND SUNDAY. UPSTREAM RAOB HEIGHT RISES SEEN ACROSS WRN CANADA WITH THIS PROGRESSIVE HIGHER AMPLITUDE RIDGE. HAVE COOLED THE LOW TEMPERATURES SUNDAY MORNING OVER CENTRAL WI WITH NEARLY CALM WINDS AND LITTLE CLOUD UNDER LOW-LEVEL RIDGING. THESE ARE BELOW MOS GUIDANCE BY ABOUT 5-7F. WARM ADVECTION WILL BEGIN TO RAISE TEMPERATURES SUNDAY AND THE FORCING DOES NOT SEEM SUFFICIENT TO CREATE PRECIPITATION PER CONSENSUS 15.12Z MODEL GUIDANCE. HOWEVER...THE WARM ADVECTION AND THERMAL RIBBON LIFTING ACROSS THE AREA WILL CREATE AN ARC OF CLOUDS ORIENTED NW-SE TO SHIFT NEWRD ACROSS THE AREA. HAVE INCREASED SKY COVER A BIT FOR SUNDAY...SOME FLURRIES MAY BE POSSIBLE BUT HAVE NOT INCLUDED THEM IN THE FORECAST. FAIRLY INTERESTING TROUGH TO SHIFT INTO THE AREA MONDAY. THE TROUGH IS CURRENTLY IN THE ERN PACIFIC APPROACHING 47N/140W PER GOES WATER VAPOR. MODEL GUIDANCE CONSENSUS FROM 15.12Z IS THAT THERE WILL NRN AND SRN ENERGY IN THIS TROUGH. THE SRN PIECE OF ENERGY IS HANDLED DIFFERENTLY BY THE LATEST GUIDANCE. THE 15.12Z NAM/SREF DEVELOP ONLY A WEAK CYCLONE VIA THE SRN ENERGY...WHILE THE GEM GLOBAL AND 15.00Z FIM MODEL ARE AGGRESSIVE WITH THE CYCLONE DEEPENING IT ALONG A KANSAS CITY TO MILWAUKEE TRACK...AND DROPPING A 4-8 INCH SNOW BAND ACROSS WI. 15.12Z ECMWF/GFS ARE SIMILAR AND OFFER A COMPROMISE BETWEEN THE TWO CAMPS WITH THE CYCLONE DEEPENING LATER...INTO MICHIGAN. HAVE GONE WITH THIS COMPROMISE ON TIMING AND INTENSITY. MONDAY WILL SEE A GULF SURGE OF MOISTURE IN THE SOUTHERLY FLOW... DEEPENING A SURFACE-BASED LAYER TO OVER 1 KM DEEP. THIS WILL BE PRE-FRONTAL IN THE SOUTHERLY FLOW AND WITHOUT DEEP CLOUD AND ICE...BUT ISENTROPIC LIFT OF 3-5 UB/S IN THE LAYER ...DZ/FZDZ WILL BE POSSIBLE. THE MOIST TONGUE IS MAINLY IN WI AND EAST AND THAT IS WHERE DZ/FZDZ CHANCES WILL BE BEST. TEMPERATURES WILL BE WARMING MONDAY WITH ABOVE FREEZING HIGHS AROUND I-90 AND SOUTH EXPECTED. THUS...DZ OR RAIN SHOWERS COULD BE FREEZING IN THE EARLY AFTERNOON IF ROADS DO NOT RESPOND TO WARMING. WITH QPFS LESS THAN 0.10 INCHES...WOULD EXPECT ONLY LIGHT ICING TO OCCUR. AS TROUGH SHIFTS EAST LATE MONDAY AND MONDAY EVENING...A TRANSITION TO SNOW WILL OCCUR FROM WEST TO EAST WITH SNOW AMOUNTS OF LESS THAN AN INCH. HAVE INCREASED PRECIPITATION CHANCES OVERALL...BUT WI LOOKS TO BE THE MAIN WEATHER AREA FOR THIS SYSTEM. THERE IS A CHANCE THIS COULD NEED AN ADVISORY IF FREEZING PRECIPITATION LOOKS MORE WIDESPREAD OR THE MORE AGGRESSIVE CYCLONE SOLUTION IN THE GEM SHOULD BECOME MORE PROBABLE. THE SPREAD IN THE CYCLOGENESIS SEEN FROM THE SRN ENERGY IN THE MODEL GUIDANCE SUGGESTS THIS IS AN UNSTABLE SYSTEM AND COULD LEAD TO FORECAST CHANGES. WILL TAKE A STEP UP IN OUR FORECAST VISIBILITY OF THIS SYSTEM. .LONG TERM...TUESDAY THROUGH FRIDAY 319 PM CST FRI FEB 15 2013 ACTIVE EXTENDED PERIOD SETTING UP WITH THE FOCUS ON A SHORT ARCTIC INTRUSION MID WEEK FOLLOWED BY THE POTENTIAL OF A WINTER STORM TO IMPACT THE UPPER MIDWEST NEXT THURSDAY NIGHT AND FRIDAY. GOING INTO TUESDAY...A LOT DEPENDS ON THE EVOLUTION AND PHASING OF THE STORM SYSTEM THAT IS EXPECTED TO TRACK THROUGH MONDAY AND MONDAY NIGHT...AND HOW MUCH ARCTIC AIR IS PULLED SOUTH IN ITS WAKE. 15.12Z GUIDANCE SHOWS SIMILAR SOLUTIONS FOR 850 MB TEMPERATURES TO PLUMMET AS LOW AS -15C TO -20C TUESDAY AND WEDNESDAY. STANDARDIZED ANOMALIES FOR THIS PERIOD RANGE FROM 1 TO 1.5 BELOW NORMAL AND WITH BROAD CYCLONIC FLOW ALOFT...IT WILL MAKE FOR A COUPLE COLD WINTER DAYS. HIGHS IN THE TEENS AND OVERNIGHT LOWS IN THE SINGLE DIGITS ABOVE ZERO...WITH OCCASIONAL LIGHT SNOW OR FLURRIES TUESDAY. THE COLD AIRMASS SETS THE STAGE FOR LATER IN THE WEEK AS A WESTERN CONUS TROUGH DEEPENS AND MOVES EAST. AS HAS BEEN ALLUDED TO IN PREVIOUS DISCUSSIONS...THE RUN-TO-RUN AND MODEL CONSISTENCY FOR THIS FEATURE REMAINS VERY HIGH. DETERMINISTIC MODELS STILL POINT FOR A SURFACE LOW TRACK THROUGH THE CENTRAL PLAINS TO NORTHERN ILLINOIS BY 12Z FRIDAY BRINGING WIDESPREAD PRECIPITATION TO THE ENTIRE AREA WITH A CLASSIC DEFORMATION BAND OF SNOW SETTING UP. LOOKING AT THE 15.12Z GFS ENSEMBLE...SURFACE LOW TRACK LOCATIONS VARY FROM EASTERN IOWA...SOUTHERN WISCONSIN...AND ILLINOIS. SIMILAR IDEAS ARE FOUND IN THE 15.00Z ECMWF ENSEMBLE. THE STABILITY AND LACK OF SPREAD WITHIN THE NUMERICAL GUIDANCE FOR THIS WEATHER SYSTEM ARE VERY HIGH. ONE ISSUE THAT MAY PRECLUDE THIS FROM BEING A MORE SIGNIFICANT EVENT IS THAT THE BOTH THE UPPER LEVEL AND SURFACE WAVES APPEAR TO BE WEAKENING AS IT APPROACHES THE UPPER MIDWEST. 500 MB STANDARDIZED ANOMALIES DROP FROM -2.5 ACROSS KANSAS TO BARELY BELOW NORMAL AS IT CROSSES THE AREA. THIS IS REFLECTED IN THE SURFACE LOW PRESSURE WHICH REMAINS AROUND 1000 MB THROUGHOUT. EARLIER RUNS SHOWED DEEPER CYCLOGENESIS WITH 980-990 MB LOWS. THE 15.12Z ECMWF REALLY DAMPENS OUT THE UPPER LEVEL AND SURFACE WAVE...BECOMING ALMOST OCCLUDED BY FRIDAY AFTERNOON. TEMPERATURE PROFILES ACROSS THE AREA CONTINUE TO SHOW AN ALL SNOW EVENT...THOUGH THERE IS A SLIGHT WARMING TREND NOTED. IF THE SYSTEM WERE TO DEEPEN AND WRAP UP MORE...THEN A PUSH OF WARMER AIR COULD PRESENT A RAIN/SNOW MIX BUT RIGHT NOW THIS IS NOT THE CASE. HAVE TRENDED PRECIPITATION CHANCES ABOVE MODEL CONSENSUS THURSDAY NIGHT GIVEN CONTINUED EXCELLENT MODEL AGREEMENT AND THE SLOWER TIMING OF THE SYSTEM. ALTHOUGH IT IS A BIT TOO EARLY TO SPECULATE ON AMOUNTS...25.12Z GFS ENSEMBLE AND 25.12Z ECMWF SHOW WIDESPREAD AMOUNTS OF 0.50 TO 0.75 INCHES OF LIQUID. SNOW RATIOS ARE NOT VERY HIGH...MOST LIKELY A BIT BELOW CLIMATOLOGICAL VALUES /10 TO 12:1/ SO IN SHORT...WARNING LEVEL /6 INCHES/ SNOW TOTALS COULD BE MET OR EXCEEDED ACROSS PARTS OF THE REGION. && .AVIATION...THROUGH 06Z SUNDAY 1048 PM CST FRI FEB 15 2013 CONFIDENCE HAS INCREASED THAT MVFR STRATUS WILL AFFECT THE TAF SITES THIS MORNING. AN AREA OF MVFR STRATUS WAS PRESENT OVER WESTERN MINNESOTA...JUST TO THE EAST OF A HIGH PRESSURE RIDGE IN EASTERN SOUTH DAKOTA. THIS STRATUS HAS BEEN MOVING EASTWARD AND EXPANDING. EXTRAPOLATION ALONG WITH NAM/RAP MODEL FORECASTS BRING THE STRATUS INTO KRST AROUND 10Z AND KLSE AROUND 12Z. FLURRIES HAVE ALSO BECOME MORE PREVALANT WITHIN THE STRATUS...AND WITH THE CONFIDENCE NOW HIGHER ABOUT THE STRATUS AFFECTING THE TAF SITES... ADDED -SHSN BACK IN. THE CLEARING TIME OF THE STRATUS IS STILL A LITTLE UNCERTAIN...BUT GIVEN THAT THE WEST SIDE OF THE STRATUS BANK IS MOVING AND DAYTIME MIXING WILL HELP OUT...GIVES CONFIDENCE THE STRATUS DECK WILL NOT GET STUCK. HAVE KEPT THE 20Z TIME FOR SCATTERING OUT OF THE CLOUDS...IN AGREEMENT TOO WITH THE NAM MODEL FORECAST. CLEAR SKIES SHOULD DOMINATE MUCH OF THE EVENING AS THE RIDGE OF HIGH PRESSURE BECOMES FIRMLY IN CONTROL. EXPECT WINDS TO GENERALLY REMAIN LIGHT...LESS THAN 10 KT...DUE TO THE HIGH PRESSURE RIDGE BUILDING IN. && .ARX WATCHES/WARNINGS/ADVISORIES... 319 PM CST FRI FEB 15 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BAUMGARDT LONG TERM...TAYLOR/BAUMGARDT AVIATION...AJ
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
836 AM EST SAT FEB 16 2013 .UPDATE... WK BUT DISTINCT MESOLOW WHICH SPUN UP INVOF OF PARENT SFC TROUGH NR KMKG ARND 0930Z CONTS TO CURL ESE THIS MORNING AND CURRENTLY WEST OF KBTL. UPSTREAM CVRG BAND WHILE NOT AS INTENSE AS EARLIER XPCD TO REINTENSIFY THROUGH LT MORNING ALG A KBIV...KAZO...KOEB LINE AS LK AGGREGATE THERMAL TROUGHING STRENGTHENS AND UPSTREAM LK MSTR FLUX MAXIMIZES INLAND. THIS MAY NECESSITATE A EWD EXPANSION OF CURRENT ADVISORY OVR ST JOE MI TO INCLUDE BRANCH AND PERHAPS EVEN HILLSDALE. TRENDING NR TERM RUC SOLUTIONS ADVERTISE A SIMILAR EVOLUTION AND EVEN DIP FOCUSED BAND DOWN TO KTOL BY LT AFTN. HWVR GIVEN THINGS STILL IN A STATE OF FLUX WILL CONT TO MONITOR DVLPMNTS AS PLACEMENT ON LOCATION OF WRN FLANK STILL UNCERTAIN. OTRWS SIG UPSTREAM NEG THETA-E ADVTN ASSOCD/W BLDG ARCTIC RIDGING LOOKS TO STIFLE ADDNL SRN LAKE DVLPMNT UNTIL LT AFTN TIMED W/FURTHER AND MORE FVRBL LL VEERING INTO SW MI/NW IN. && .SHORT TERM... /TODAY THROUGH SUNDAY NIGHT/ PRIMARY FOCUS REMAINS ON LAKE EFFECT SNOW AMOUNTS AND IMPACTS ACROSS FAR NORTHERN INDIANA AND SOUTHWEST LOWER MICHIGAN TODAY THROUGH SUNDAY MORNING... A DIGGING UPPER TROUGH AXIS AND EMBEDDED SHORTWAVE ENERGY WILL PIVOT THROUGH THE SOUTHERN GREAT LAKES REGION THIS MORNING WITH THE CORE OF COLD AIR (7H TEMPS TO -28C) DROPPING THROUGH THIS AFTERNOON INTO TONIGHT. THIS WILL RESULT IN EXTREME OVER-LAKE INSTABILITY WITH IMPRESSIVE LAKE-7H TEMP DIFFERENTIALS NEAR 30C AND UVM/MOISTURE MAXIMIZED WITHIN THE DGZ THROUGH THE EVENT. HOWEVER...MORE WESTERLY 300 DEGREE LOW LEVEL TRAJECTORIES AND A SUBSTANTIAL DIURNAL COMPONENT TODAY WILL LIMIT ORGANIZATION (MORE CELLULAR) WITH DRY UPPER MIDWEST ENTRAINMENT AND LARGE SCALE SUBSIDENCE BEHIND THIS MORNING`S MID LEVEL WAVE ALSO LIMITING FACTORS FOR SIGNIFICANT SNOW ACCUMS. THIS DRYING/POOR FETCH COMBO COULD EVEN RESULT IN A PERIOD OF LITTLE/NO SNOW SHOWER ACTIVITY BY LATE MORNING/EARLY AFTERNOON. THIS WILL LIKELY KEEP SNOW TOTALS IN CHECK THROUGH 00Z WITH LOCATIONS NORTH OF HWY 6 IN INDIANA/MI STILL EXPECTING SNOW ACCUMS BETWEEN 1 AND 4 INCHES. ELSEWHERE...EXPECT VERY COLD CONDITIONS WITH ISOLATED TO SCATTERED SNOW SHOWERS POSSIBLE...ESPECIALLY EARLY THIS MORNING ALONG THE SYNOPTIC TROUGH WITH DUSTING TO HALF INCH TYPE ACCUMS POSSIBLE. SLIGHT IN-CLOUD VEERING TO A MORE FAVORABLE 320-330 DEGREE FETCH...LITTLE/NO SHEAR...AND FAVORABLE DIURNAL TIMING SHOULD COMBINE TO ALLOW AN INTENSE SHORE PARALLEL SNOW BAND TO MATERIALIZE WITHIN AN INTENSIFYING DIRECT THERMAL CIRCULATION/AGGREGATE SFC TROUGH TONIGHT. HI-RES GUIDANCE CONTINUES TO SUGGEST MESOLOW DEVELOPMENT WHICH WILL NO DOUBT DETERMINE WHERE THIS BAND SETS UP/PIVOTS OVERNIGHT INTO EARLY SUNDAY MORNING. INTENSE SNOWFALL RATES OF 2-3 INCHES PER HOUR WILL BE POSSIBLE WITHIN THIS BAND. QUESTIONS OBVIOUSLY AT THIS JUNCTURE REMAIN EXACTLY WHERE THIS SETS UP AND POSSIBLE INTERFERENCE (FLOW INTERRUPTION) FROM ANY MESOLOW. A 00Z MODEL CONSENSUS DOES FAVOR NORTHERN/EASTERN BERRIEN, WESTERN CASS MI, AND ST JOE INDIANA AS THE PIVOT POINT WITH THE POTENTIAL FOR SEVERAL HOURS OF HEAVY SNOW. FOR NOW WILL HOLD SERVE WITH CURRENT HEADLINES GIVEN UNCERTAINTIES. REGARDLESS THERE IS THE POTENTIAL FOR SIGNIFICANT LAKE EFFECT SNOW MAINLY LATER THIS EVENING INTO THE OVERNIGHT HOURS. ELSEWHERE...MAINLY DRY AND COLD. WAA WITH RIDGING ALOFT AND BACKING LOW LEVEL TRAJECTORIES WILL BRING ANY LINGERING LAKE EFFECT SNOW TO AN END BY EARLY SUNDAY AFTERNOON WITH NO SENSIBLE WX CONCERNS SUNDAY AFTERNOON/NIGHT. && .LONG TERM... /MONDAY THROUGH FRIDAY/ ALL IN ALL LITTLE SIG CHNG FM YDAY ANALYSIS WITH OVERALL INCRSD CONFIDENCE WRT QPF/TIMING ASSOCD WITH LOW/MODERATE AMPLITUDE NRN STREAM WAVE /CRNTLY APPROACHING PAC NW/ TO MAINTAIN PROGRESSIVE NATURE INTO ERLY NEXT WEEK. SYSTEM TRAVERSING SCNTL CAN/NRN PLAINS MONDAY TO SLOW TUESDAY/INCRSGLY VERTICALLY STACKED AS SRN END/SE CO FNTL WAVE PROCEEDS INTO OCCLUSAL IN NRN GRTLKS. SOME DISCOUNT/CAUTION TO THE MORE RAPID NAM/SREF SIGNALS...PER VARIANCE AS NOTED IN PMDHMD. AT SAME TIME DIFFICULT TO UNDERESTIMATE SHALLOW/DRY/COLD CP AIR ADVANCE AFFORDED BY POLEWARD CONNECTIVITY AT SFC/LLVLS OF SUCH INTENSE NRN MANITOBA ANTICYCLONE. ATTEMPT TO FURTHER DETAIL TIMING OF RAFL ONSET THROUGH CWA WITH SIGNALS OF DEEP MSTR/UVM HOLDING OFF TIL LATE IN DAY ONCE LATE OPEN GOMEX FEED/NRN TERMINUS OF HIGHLY INTENSE 925-8H LLJ TO 65 KTS AIMING FM MO BOOTHILL THROUGH MOUTH OF OH RVR INTO FAR SWRN IN TO DEMAND FORCED MOIST ASCENT...MOST LIKELY UNTIL LATE AFTN/21 UTC MON TIMEFRAME. RAPID EWD SHIFT OF FEATURE INTO UPR OH VLY BY 06 UTC TO GRTLY LIMIT UVM ACRS RGN AFT RAFL SLUG...WITH TRANSITION TO LIGHTER RA/SN MIX TO SN THROUGH THE NIGHT WITH LITTLE/NO ACCUMS. THEREAFTER...MINOR LES RESPONSE PER WRLY FLOW AND MUTED MIXED LYR DEPTH. ALL EYES RMN ON LATE WEEK SYSTEM. SLIGHT NWD SHIFT SFC/ALOFT NOTED PER MULTIMODEL CONSENSUS...THOUGH CERTAINLY NOT SIG ENOUGH TO DISMISS. INTMTN/SWRN STATES TROF AT APEX 00 UTC THU/F120. THEREAFTER HOLD DOUBTS AS TO EXACT TRACK. LOW AMPLITUDE/WEAKNESS NOTED IN DOWNSTREAM RIDGE THEREAFTER AS SYSTEM EJECTS FM ERN NM INTO CNTL PLAINS DY6. THIS DOWNSTREAM WEAKNESS COULD AFFORD POTNL TO BIFURCATE AND MAINTAIN A MORE EWD MOMENTUM INTO DY7. ALSO TREND TWRDS CPC 8-14 ANALOGS COULD SUGGEST A POTNL REXING OF SYSTEM PER WEAK/ANTECEDENT SRN CANADA/JAMES BAY RIDGE AIDED BY A POS HGHT ANOMOLY PHASE THEREAFTER INTO DY8. POTNL STILL HOLDS OUT AS BEST SYNOPTIC SYSTEM SINCE DEC 26 AS THU NIGHT ONSLAUGHT OF INITIAL STRONG ISENT LIFT/STRONG EVAP/STRONGER DYNAMIC COOLING PROCESSES TO ELICIT RAPID WETBULB COLLAPSE FOR SN/PSBLY BECMG HVY ACRS SWRN/WRN CWA BY ERLY FRI. THEREAFTER A DOWNSTREAM RIDGE SPLIT/REX DVLPMNT REMOTELY COULD OFFER A STALLED DEEP SYSTEM TO SLOWLY WITHER ON VINE ACRS NRN IN/SRN LWR MI...AT LEAST THROUGH HERO FCSTR EYES. LARGE STANDARD DEVIATION SPREAD PER MEDIUM RANGE MODEL ACCUMULATIONS. SAN COMPACTION WITH CLIMATOLOGICAL MEAN NEAR 14/1 RATIOS USED AFFORDED RANGES GNRLY WITHIN 3-7 INCH RANGE...FWIW AT F144-180. && .AVIATION... /06 UTC TAFS/ LAKE EFFECT SNOW SHOWERS WILL IMPACT SBN THROUGH THE PERIOD...ESPECIALLY THIS MORNING AND AGAIN SATURDAY NIGHT. THIS WILL RESULT IN VARIABLE FLIGHT CONDITIONS THROUGH THE PERIOD. THERE COULD BE A LULL IN THE SNOW SHOWER ACTIVITY LATER THIS MORNING INTO THE EARLY AFTERNOON AS SUBSIDENCE/DRYING BUILDS IN BRIEFLY BEHIND THIS MORNING`S WEAK MID LEVEL SHORTWAVE. AN INTENSE SINGLE BAND MAY SET UP OVER SBN SATURDAY NIGHT WITH LIFR CONDITIONS AND INTENSE 1-3 INCH PER HOUR SNOWFALL RATES POSSIBLE. EXPECT MAINLY DRY/VFR CONDITIONS AT FWA...ALTHOUGH CANNOT RULE OUT A FEW SNOW SHOWERS THROUGH THE PERIOD WHICH COULD BRIEFLY REDUCE VISBYS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...LAKE EFFECT SNOW ADVISORY UNTIL 4 AM EST /3 AM CST/ SUNDAY FOR INZ003>005. MI...LAKE EFFECT SNOW ADVISORY UNTIL 4 AM EST SUNDAY FOR MIZ079. LAKE EFFECT SNOW WARNING UNTIL 10 AM EST SUNDAY FOR MIZ077-078. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 10 AM EST SUNDAY FOR LMZ043-046. && $$ SHORT TERM...STEINWEDEL LONG TERM...MURPHY AVIATION...STEINWEDEL UPDATE...T
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
901 AM EST SAT FEB 16 2013 .SYNOPSIS... ISSUED AT 330 AM EST SAT FEB 16 2013 OCCASIONAL SNOW SHOWERS WILL CONTINUE TODAY AND INTO THIS EVENING. THE SNOW WILL BE HEAVY AT TIMES. LAKE SHORE AREAS WILL PICK UP ANOTHER 2 TO 4 INCHES...WHILE INLAND AREAS SEE 1 TO 2 INCHES. THE SNOW IS EXPECTED TO DIMINISH AFTER MIDNIGHT. BY MONDAY LOW PRESSURE WILL MOVE INTO THE UPPER MIDWEST. THIS SYSTEM WILL BRIEFLY BRING TEMPERATURES UP TO AROUND 40 BY MONDAY AFTERNOON. A PERIOD OF RAIN IS EXPECTED MONDAY AFTERNOON...THAT WILL TURN TO SNOW MONDAY NIGHT AND CONTINUE ON TUESDAY. MORE SNOW LOOKS LIKELY BY THURSDAY NIGHT AND FRIDAY. && .UPDATE... ISSUED AT 900 AM EST SAT FEB 16 2013 AFTER FURTHER CONSIDERATION...WILL BE UPGRADING MASON AND OCEANA TO A WARNING. RAP GUIDANCE SUGGESTS THAT AFTER A LULL THIS MORNING... ANOTHER SIGNIFICANT BAND MAY EXTEND FROM THESE COUNTIES THROUGH MUSKEGON...ALLEGAN...AND KALAMAZOO COUNTIES. UPDATE ISSUED AT 848 AM EST SAT FEB 16 2013 HAVE RECEIVED RECENT 8-12" SNOW REPORTS FROM SEVERAL LOCATIONS IN MASON AND OCEANA COUNTIES BENEATH AN AREA OF SATELLITE IR TEMPERATURES THAT WERE COLDER THAN -30C BETWEEN 11-12Z. 830 AM AWOS OBSERVATION AT HART INDICATES VISIBILITY BELOW 1/4 MILE. SUSPECT STRONG FRONTOGENETIC FORCING HAS BEEN AT PLAY AS TEMPERATURES AT RQB AND CAD HAD DROPPED AS MUCH AS 10 DEGREES OR MORE OVER THE PAST FEW HOURS. PRESENT THINKING IS THAT FGEN FORCING SHOULD DECREASE ALONG WITH MOST INTENSE SNOW THROUGH 10 AM. THIS IS SUPPORTED BY THE 16/09Z RUN OF THE HRRR...WHICH TAPERS PRECIP AND MOVES IT INLAND THROUGH 15Z. BELIEVING WE ARE ON A DOWNWARD TREND AFTER A PEAK IN SNOWFALL INTENSITY...WILL KEEP THE ADVISORY GOING IN THIS AREA AND UPDATE WITH THE LATEST THINKING. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 330 AM EST SAT FEB 16 2013 A RATHER DISORGANIZED PATTERN SO FAR EARLY THIS MORNING. A SURFACE TROUGH HAS BEEN CROSSING THE LAKE EARLY THIS MORNING AND THE WIND PATTERN AROUND THIS TROUGH HAS BEEN DISRUPTING ANY ORGANIZED LAKE EFFECT BANDS. THERE HAS BEEN A PERSISTENT BAND ACROSS THE NW COUNTIES NEAR LUDINGTON AND WHITEHALL...BUT OTHER SNOW BANDS HAVE BEEN FAIRLY TRANSITORY...KEEPING ACCUMS DOWN. THE SURFACE TROUGH LINGERS OVER THE AREA MUCH OF TODAY...SO FEEL WE MAY STRUGGLE TO GET PERSISTENT LES BANDS. RAP13 LOW LEVEL CONVERGENCE FIELDS SUGGEST THE LDM BAND MAY HOLD PAT MUCH OF THE DAY. IF THIS HOLDS TRUE...THIS BAND COULD PUT DOWN ANOTHER FOUR INCHES OR SO. A BETTER FLAIR UP IS INDICATED TOWARD 16Z FOR THE SW COUNTIES AND THIS IS PAINTED TO LAST THROUGH MUCH OF THE AFTERNOON. ALSO OF INTEREST IS A SYNOPTIC CONVERGENCE BAND THAT FLAIRS UP NORTH OF THE SURFACE TROUGH ALONG HIGHWAY 10 BY MID TO LATE AFTERNOON TODAY. IF THIS HOLDS TRUE THERE COULD BE A BURST OF SNOW ACROSS ALL OF THE NORTHERN COUNTIES INTO THIS EVENING. NEEDLESS TO SAY A RATHER COMPLEX PATTERN FOR TODAY. THOUGHT ABOUT DROPPING SOME OF THE COUNTIES IN THE ADVISORY AS THE LAKE EFFECT DOES NOT LOOK AS ROBUST ANYMORE. HOWEVER SINCE SNOW WILL STILL OCCUR...IT IS SORT OF HARD TO DROP HEADLINES IN THE MIDDLE OF AN EVENT. SO WILL LEAVE THE ADVISORY AS IS...ALTHOUGH WILL HIGHLIGHT SLIGHTLY LESS ACCUMS. ON THE OTHER HAND...INLAND AREAS COULD SEE A BIT MORE SNOW THEN WHAT IS CURRENTLY IN THE FORECAST DUE TO THE SYNOPTIC FEATURES. SO HAVE BUMPED UP ACCUMS A BIT INLAND... ESPECIAL NEAR HIGHWAY 10 TO COVER THE POSSIBLE CONVERGENCE BURST LATE TODAY INTO THIS EVENING. THE SNOW SHOULD BE DWINDLING AFTER MIDNIGHT AS THE SYSTEM PULLS AWAY AND INVERSION LEVELS COME DOWN. WILL CONTINUE WITH THE CHANCE POPS ON SUNDAY ALONG THE LAKE SHORE. WINDS WILL PIVOT FROM THE NNW EARLY IN THE DAY TO SW TOWARD MID DAY. THIS SHOULD PUSH ANY LAKE BAND INLAND...PRODUCING A BRIEF SNOW SHOWER MAINLY WEST OF U.S. 131. THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE MONDAY SYSTEM... BRINGING IT IN QUICKER. HAVE INCREASED POPS TO LIKELY BY MID TO LATE AFTERNOON. SHOULD BE WARM ENOUGH OF MOSTLY RAIN...ALTHOUGH A MIX SHOULD FALL OVER CENTRAL LOWER. .LONG TERM...(MONDAY NIGHT THROUGH FRIDAY) ISSUED AT 330 AM EST SAT FEB 16 2013 ACTIVE WEATHER PATTERN NEXT WEEK WITH TWO STORMS TO WATCH. A CLIPPER MOVES MOVES EAST MONDAY NIGHT WITH RAIN AND SNOW MIX CHANGING TO SNOW...FOLLOWED BY WEST FLOW LAKE EFFECT SNOW FROM TUESDAY AFTERNOON INTO WEDNESDAY. SFC AND SHORTWAVE UPPER RIDGING MOVES IN TO END THE LAKE EFFECT ON WEDNESDAY NIGHT...BUT THE LULL WILL BE SHORT LIVED AS A STORM TAKES SHAPE ACROSS THE PLAINS AND MOVES NORTHEAST SPREADING A BAND OF SNOW INTO LOWER MICHIGAN BY LATE THURSDAY. SNOW COULD BE HEAVY THURSDAY NIGHT AS AN AREA OF STRONG UPPER LEVEL DIVERGENCE AND DEEP LIFT MOVES OVER LOWER MICHIGAN. SNOW WILL CONTINUE ON FRIDAY AS AN UPPER LOW MOVES ACROSS ALTHOUGH WITH LESS INTENSITY AS DEEPER LIFT AND MOISTURE MOVES EAST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 651 AM EST SAT FEB 16 2013 LAKE EFFECT SNOW SHOWERS WILL BRING AREAS OF IFR AND PATCHY LIFR TODAY. CONDITIONS WILL VARY QUITE A BIT WITH VFR AND MVFR PREVAILING WELL INLAND. WINDS WILL BE NORTHWEST AT OR BELOW 10 KNOTS. THE SNOW WILL BEGIN TO LET UP THIS EVENING WITH MOSTLY VFR EXPECTED LATER TONIGHT. && .MARINE... ISSUED AT 330 AM EST SAT FEB 16 2013 WILL KEEP MARINE HEADLINE AS IS...SCA THROUGH TONIGHT. && .HYDROLOGY... ISSUED AT 330 AM EST SAT FEB 16 2013 COLDER AIR HAS LOCKED UP ANY FURTHER SNOW MELT. WE WILL SEE A BRIEF WARM UP ON MONDAY WITH TEMPS REACHING AROUND 40 ALONG WITH SOME RAIN. SINCE THE WARM UP WILL BE BRIEF AND THE RAIN SHOULD BY LESS THAN A QUARTER INCH...NO HYDRO ISSUES ARE EXPECTED. HOWEVER A FLOOD ADVISORY REMAINS IN EFFECT FOR HIGH WATERS ON THE PERE MARQUETTE NEAR SCOTTVILLE. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST THIS EVENING FOR MIZ037-043-050-056-064-071-072. LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ038- 044-057-065-073. LM...SMALL CRAFT ADVISORY UNTIL 4 AM EST SUNDAY FOR LMZ844>849. && $$ UPDATE...TJT SYNOPSIS...JK SHORT TERM...JK LONG TERM...OSTUNO AVIATION...OSTUNO HYDROLOGY...JK MARINE...JK
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
642 AM CST SAT FEB 16 2013 .UPDATE... .SHORT TERM... MULTI MODEL BLEND OF RUC...HRRR...GEMREG...SREF...NAM...ECM PRODUCED WARMER TEMPS TODAY AND SUNDAY AS WARRANTED BY THE KUNR SOUNDING. NO DISCERNIBLE CHANGE OCCURRED TO THE ONGOING WEATHER USING THE SAME BLEND. A NEW FCST IS OUT...KIML COULD REACH 60F ON SUNDAY. OVERALL THE SNOW MOVES OUT QUICKLY THIS MORNING WITH CLEARING TO FOLLOW JUST A RAPIDLY ALONG AND WEST OF HIGHWAY 83. CLOUDS STAY IN LONGER EAST OF 83 AS ANOTHER BATCH OF CLOUDS MOVES DOWN FROM THE DAKOTAS LATER THIS MORNING. .PREV DISCUSSION... /ISSUED 515 AM CST SAT FEB 16 2013/ UPDATE... AVIATION... MVFR IN SNOW AND LOW CIGS WILL MOVE SLOWLY EAST TODAY. THE RUC AND NAM KEEP MVFR CIGS IN PLACE FROM KVTN-KTIF EAST THROUGHOUT THE AFTN EVEN AFTER THE SNOW ENDS WHILE THE GFS OPENS UP THE AREA TO VFR BY 18Z ONCE THE SNOW MOVES OUT. THE FCST FOLLOWS THE GFS...THE FASTER SOLNS. THE GENERAL FEELING IS ONCE THE SNOW ENDS...CIGS WILL IMPROVE TO VFR. VFR IS EXPECTED ALL AREAS TONIGHT IF THE GFS VERIFIES. PREV DISCUSSION... /ISSUED 413 AM CST SAT FEB 16 2013/ UPDATE... SHORT TERM... RAN A BLEND OF ECM...GEMREG...NAM...RUC AND HRRR FOR THE ONGOING LIGHT SNOW ASSOCIATED WITH THE WARM FRONT ACROSS WRN NEB. THIS STILL GIVES LESS THAN AN INCH ACCUMULATION BUT THE RADAR IS LOOKING PRETTY ROBUST SO WE WILL HAVE TO WAIT FOR THE SNOW TO PASS OVER AN OBSERVATION SITE. THE LATEST DETAILS ON THE WEDS-THUR STORM ARE OUT IN THE FORM OF A SPECIAL WEATHER STATEMENT. PREV DISCUSSION... /ISSUED 337 AM CST SAT FEB 16 2013/ SHORT TERM...THROUGH 00Z MONDAY. THE GEMREG...NAM...RUC AND HRRR SHOW A DEVELOPING WARM FRONT MOVING EAST THROUGH NRN NEB THIS MORNING AND WEAKENING DURING THE AFTN. RADAR SUPPORTS THE DEVELOPMENT OF SCATTERED SNOW SHOWERS. SKIES SHOULD CLEAR OUT BEHIND THE WARM FRONT THROUGHOUT THE MORNING...AFTN AND EVENING HOURS. TEMPERATURES TODAY RANGE FROM NEAR 40 NORTHEAST TO MID 50S SOUTHWEST. LOW THROUGHOUT THE FCST AREA TONIGHT FALL TO AROUND 20. LONG TERM...00Z MONDAY AND BEYOND. MAIN FOCUS IN THE EXTENDED PERIOD REMAINS CENTERED ON THE POTENTIALLY SIGNIFICANT WINTER STORM POISED TO ARRIVE LATE WEDNESDAY LASTING INTO FRIDAY. CONFIDENCE IS INCREASING WITH THIS STORM AS THERE REMAINS STRONG SYNOPTIC AGREEMENT THROUGH THE EXTENDED PERIOD. MONDAY...BRIEF SHORTWAVE RIDGING ALOFT WILL BREAK DOWN AND BUILD EAST OF THE FORECAST AREA AS A SHORTWAVE TROUGH ADVANCED FROM THE ROCKIES ACROSS THE PLAINS. LONGER RANGE SOLUTIONS CONTINUE TO SHOW LIMITED SUPPORT FOR PRECIPITATION PRODUCTION...THUS WILL CONTINUE THE DRY FORECAST FOR NOW. THE WAVE WILL PULL A COLD FRONT ACROSS THE CWA LATE SUNDAY INTO EARLY MONDAY...WITH STRONG CAA AND A TIGHT GRADIENT TO FOLLOW...MONDAY WILL BE BLUSTERY WITH HIGHS RUNNING 15F OR MORE COOLER THAN SUNDAY AFTERNOON. INTO TUESDAY...THE OVERALL SYNOPTIC PATTERN REMAINS FAIRLY PROGRESSIVE AS SHORTWAVE RIDGING BUILDS ACROSS WESTERN NEBRASKA...HOWEVER TEMPERATURES WILL BE SLOW TO WARM TUESDAY AND WEDNESDAY HOWEVER AS EASTERLY FLOW WILL RECYCLE ARCTIC AIR BACK ACROSS MUCH OF THE CWA. SEEING A LARGE RANGE IN HIGHS FOR BOTH MONDAY AND TUESDAY...WITH 20S ACROSS NORTH CENTRAL NEBRASKA...AND POSSIBLY UPPER 30S TO LOW 40S ACROSS THE FAR SOUTHWEST. ATTENTION NOW TURNS TO THE POTENTIALLY BIG WINTER STORM FOR WEDNESDAY NIGHT AND THURSDAY. LONG RANGE SOLUTIONS CONTINUE TO ADVERTISE A STRONG UPPER LOW WHICH WILL EJECT FROM THE FOUR CORNERS REGION WEDNESDAY NIGHT INTO THE CENTRAL PLAINS BY EARLY THURSDAY. CYCLOGENESIS WILL BE ONGOING ACROSS THE EASTERN PLAINS OF COLORADO ON WEDNESDAY...WITH A RAPID DEEPENING OF THE SURFACE LOW EXPECTED. GIVEN STRONG SURFACE HIGH PRESSURE OF ~1040MB OVER THE GREAT LAKES REGION...AN INCREASING PRESSURE GRADIENT WILL DEVELOP ACROSS THE CWA...WITH THE POTENTIAL OF 25-30 MPH WIND GUSTS WEDNESDAY AND THURSDAY. THE MODELS ALSO SUGGEST PLENTIFUL MOISTURE ADVECTION IN ADVANCE OF THE SYSTEM...WITH EASTERLY UPSLOPE POSSIBLY ALLOWING FOR SNOW PRODUCTION AS EARLY AS LATE WEDNESDAY NIGHT. MEANWHILE...DOWNSTREAM OF THE UPPER TROUGH...RIDGING AND PV DESTRUCTION ACROSS THE UPPER MISSISSIPPI RIVER VALLEY WILL ALLOW THE TROUGH/CLOSED LOW TO BECOME NEGATIVELY TILTED...WITH THE PROGRESSION OF THE H5 LOW SLOWED. MODEL CONSENSUS INDICATES THE TRACK OF THE H5 LOW FROM SE COLORADO INTO NEBRASKA FROM 06Z THURSDAY THROUGH 00Z FRIDAY...PLACING MUCH OF THE FORECAST AREA UNDER A BROAD DEFORMATION BAND FOR A 12-18 HOUR PERIOD....THUS THE POTENTIAL OF A LONG SNOW EVENT IS POSSIBLE. THERE ARE A FEW DIFFERENCES WITH THE TRACK OF THE H5 LOW...MAINLY THE GFS AND ENSEMBLES ARE MORE PROGRESSIVE WITH THE TRACK OF THE LOW...CARRYING IT INTO SOUTHEASTERN NEBRASKA BY 00Z FRIDAY. THE EC WOBBLES THE H5 LOW NORTHWARD THROUGH CENTRAL NEBRASKA INTO SOUTH DAKOTA BY 06Z FRIDAY. REGARDLESS OF THE DIFFERENCES...MEAN /GFS AND EC/ QPF ACCUMULATION ARE CLOSE TO EACH OTHER /~.75 OF INCH AT KLBF/...WITH THE ENSEMBLES RUNNING SLIGHTLY HIGHER /.85/...ALL OF THIS IS EXPECTED TO FALL AS SNOW...POSSIBLY WIND DRIVEN. GIVEN THE INGREDIENTS...A MAJOR WINTER STORM IS TAKING SHAPE. AVIATION... SHORT RANGE PROJECTIONS INDICATE LIGHT SNOW OR FLURRIES MOVING INTO NORTH CENTRAL NEBRASKA BY 12Z AND ARE MOST LIKELY NORTH AND EAST OF A VTN-BBW LINE. IN THAT AREA...CEILINGS ARE LIKELY TO BE LESS THAN 1000 FEET AGL AND VISIBILITY LESS THAN 3SM. HOWEVER...AT THIS TIME...IT APPEARS THAT VTN...TIF AND BBW WILL BE ON THE WESTERN EDGE WITH CEILINGS 1000-2000 FEET AGL AND WE WILL KEEP THE INSTRUMENT CONDITIONS OUT OF THE TERMINAL FORECAST FOR VTN FOR THE TIME BEING. IN THE REST OF CENTRAL AND WESTERN NEBRASKA...CEILINGS ARE LIKELY TO BE ABOVE 3000 FEET AGL WITH NO RESTRICTIONS TO VISIBILITY. WIND IS EXPECTED TO INCREASE SATURDAY MORNING AND BECOME 300-320 AT 10-14G20-24KT 18Z AND LATER. LOOKING AT THE SHORT TERM FORECAST SOUNDINGS FOR LBF...I SEE THAT WIND INCREASES SHARPLY AT THE TOP OF THE SURFACE INVERSION JUST ABOVE 2000 FEET AGL WITH SPEED CHANGE OF ABOUT 30KT AND ABOUT 30 DEGREES CHANGE IN DIRECTION. AT THIS TIME... IT APPEARS THAT THE SHEAR WILL BE HIGHER THAN THE THRESHOLD ALTITUDE OF 2000 FEET AGL AND WILL NOT BE INCLUDED IN THE TERMINAL FORECAST FOR LBF. THE TIME OF THE GREATEST RISK OF LOW LEVEL WIND SHEAR WILL BE 12-15Z. && .LBF WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION....CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
515 AM CST SAT FEB 16 2013 .UPDATE... .AVIATION... MVFR IN SNOW AND LOW CIGS WILL MOVE SLOWLY EAST TODAY. THE RUC AND NAM KEEP MVFR CIGS IN PLACE FROM KVTN-KTIF EAST THROUGHOUT THE AFTN EVEN AFTER THE SNOW ENDS WHILE THE GFS OPENS UP THE AREA TO VFR BY 18Z ONCE THE SNOW MOVES OUT. THE FCST FOLLOWS THE GFS...THE FASTER SOLNS. THE GENERAL FEELING IS ONCE THE SNOW ENDS...CIGS WILL IMPROVE TO VFR. VFR IS EXPECTED ALL AREAS TONIGHT IF THE GFS VERIFIES. && .PREV DISCUSSION... /ISSUED 413 AM CST SAT FEB 16 2013/ UPDATE... SHORT TERM... RAN A BLEND OF ECM...GEMREG...NAM...RUC AND HRRR FOR THE ONGOING LIGHT SNOW ASSOCIATED WITH THE WARM FRONT ACROSS WRN NEB. THIS STILL GIVES LESS THAN AN INCH ACCUMULATION BUT THE RADAR IS LOOKING PRETTY ROBUST SO WE WILL HAVE TO WAIT FOR THE SNOW TO PASS OVER AN OBSERVATION SITE. THE LATEST DETAILS ON THE WEDS-THUR STORM ARE OUT IN THE FORM OF A SPECIAL WEATHER STATEMENT. PREV DISCUSSION... /ISSUED 337 AM CST SAT FEB 16 2013/ SHORT TERM...THROUGH 00Z MONDAY. THE GEMREG...NAM...RUC AND HRRR SHOW A DEVELOPING WARM FRONT MOVING EAST THROUGH NRN NEB THIS MORNING AND WEAKENING DURING THE AFTN. RADAR SUPPORTS THE DEVELOPMENT OF SCATTERED SNOW SHOWERS. SKIES SHOULD CLEAR OUT BEHIND THE WARM FRONT THROUGHOUT THE MORNING...AFTN AND EVENING HOURS. TEMPERATURES TODAY RANGE FROM NEAR 40 NORTHEAST TO MID 50S SOUTHWEST. LOW THROUGHOUT THE FCST AREA TONIGHT FALL TO AROUND 20. LONG TERM...00Z MONDAY AND BEYOND. MAIN FOCUS IN THE EXTENDED PERIOD REMAINS CENTERED ON THE POTENTIALLY SIGNIFICANT WINTER STORM POISED TO ARRIVE LATE WEDNESDAY LASTING INTO FRIDAY. CONFIDENCE IS INCREASING WITH THIS STORM AS THERE REMAINS STRONG SYNOPTIC AGREEMENT THROUGH THE EXTENDED PERIOD. MONDAY...BRIEF SHORTWAVE RIDGING ALOFT WILL BREAK DOWN AND BUILD EAST OF THE FORECAST AREA AS A SHORTWAVE TROUGH ADVANCED FROM THE ROCKIES ACROSS THE PLAINS. LONGER RANGE SOLUTIONS CONTINUE TO SHOW LIMITED SUPPORT FOR PRECIPITATION PRODUCTION...THUS WILL CONTINUE THE DRY FORECAST FOR NOW. THE WAVE WILL PULL A COLD FRONT ACROSS THE CWA LATE SUNDAY INTO EARLY MONDAY...WITH STRONG CAA AND A TIGHT GRADIENT TO FOLLOW...MONDAY WILL BE BLUSTERY WITH HIGHS RUNNING 15F OR MORE COOLER THAN SUNDAY AFTERNOON. INTO TUESDAY...THE OVERALL SYNOPTIC PATTERN REMAINS FAIRLY PROGRESSIVE AS SHORTWAVE RIDGING BUILDS ACROSS WESTERN NEBRASKA...HOWEVER TEMPERATURES WILL BE SLOW TO WARM TUESDAY AND WEDNESDAY HOWEVER AS EASTERLY FLOW WILL RECYCLE ARCTIC AIR BACK ACROSS MUCH OF THE CWA. SEEING A LARGE RANGE IN HIGHS FOR BOTH MONDAY AND TUESDAY...WITH 20S ACROSS NORTH CENTRAL NEBRASKA...AND POSSIBLY UPPER 30S TO LOW 40S ACROSS THE FAR SOUTHWEST. ATTENTION NOW TURNS TO THE POTENTIALLY BIG WINTER STORM FOR WEDNESDAY NIGHT AND THURSDAY. LONG RANGE SOLUTIONS CONTINUE TO ADVERTISE A STRONG UPPER LOW WHICH WILL EJECT FROM THE FOUR CORNERS REGION WEDNESDAY NIGHT INTO THE CENTRAL PLAINS BY EARLY THURSDAY. CYCLOGENESIS WILL BE ONGOING ACROSS THE EASTERN PLAINS OF COLORADO ON WEDNESDAY...WITH A RAPID DEEPENING OF THE SURFACE LOW EXPECTED. GIVEN STRONG SURFACE HIGH PRESSURE OF ~1040MB OVER THE GREAT LAKES REGION...AN INCREASING PRESSURE GRADIENT WILL DEVELOP ACROSS THE CWA...WITH THE POTENTIAL OF 25-30 MPH WIND GUSTS WEDNESDAY AND THURSDAY. THE MODELS ALSO SUGGEST PLENTIFUL MOISTURE ADVECTION IN ADVANCE OF THE SYSTEM...WITH EASTERLY UPSLOPE POSSIBLY ALLOWING FOR SNOW PRODUCTION AS EARLY AS LATE WEDNESDAY NIGHT. MEANWHILE...DOWNSTREAM OF THE UPPER TROUGH...RIDGING AND PV DESTRUCTION ACROSS THE UPPER MISSISSIPPI RIVER VALLEY WILL ALLOW THE TROUGH/CLOSED LOW TO BECOME NEGATIVELY TILTED...WITH THE PROGRESSION OF THE H5 LOW SLOWED. MODEL CONSENSUS INDICATES THE TRACK OF THE H5 LOW FROM SE COLORADO INTO NEBRASKA FROM 06Z THURSDAY THROUGH 00Z FRIDAY...PLACING MUCH OF THE FORECAST AREA UNDER A BROAD DEFORMATION BAND FOR A 12-18 HOUR PERIOD....THUS THE POTENTIAL OF A LONG SNOW EVENT IS POSSIBLE. THERE ARE A FEW DIFFERENCES WITH THE TRACK OF THE H5 LOW...MAINLY THE GFS AND ENSEMBLES ARE MORE PROGRESSIVE WITH THE TRACK OF THE LOW...CARRYING IT INTO SOUTHEASTERN NEBRASKA BY 00Z FRIDAY. THE EC WOBBLES THE H5 LOW NORTHWARD THROUGH CENTRAL NEBRASKA INTO SOUTH DAKOTA BY 06Z FRIDAY. REGARDLESS OF THE DIFFERENCES...MEAN /GFS AND EC/ QPF ACCUMULATION ARE CLOSE TO EACH OTHER /~.75 OF INCH AT KLBF/...WITH THE ENSEMBLES RUNNING SLIGHTLY HIGHER /.85/...ALL OF THIS IS EXPECTED TO FALL AS SNOW...POSSIBLY WIND DRIVEN. GIVEN THE INGREDIENTS...A MAJOR WINTER STORM IS TAKING SHAPE. AVIATION... SHORT RANGE PROJECTIONS INDICATE LIGHT SNOW OR FLURRIES MOVING INTO NORTH CENTRAL NEBRASKA BY 12Z AND ARE MOST LIKELY NORTH AND EAST OF A VTN-BBW LINE. IN THAT AREA...CEILINGS ARE LIKELY TO BE LESS THAN 1000 FEET AGL AND VISIBILITY LESS THAN 3SM. HOWEVER...AT THIS TIME...IT APPEARS THAT VTN...TIF AND BBW WILL BE ON THE WESTERN EDGE WITH CEILINGS 1000-2000 FEET AGL AND WE WILL KEEP THE INSTRUMENT CONDITIONS OUT OF THE TERMINAL FORECAST FOR VTN FOR THE TIME BEING. IN THE REST OF CENTRAL AND WESTERN NEBRASKA...CEILINGS ARE LIKELY TO BE ABOVE 3000 FEET AGL WITH NO RESTRICTIONS TO VISIBILITY. WIND IS EXPECTED TO INCREASE SATURDAY MORNING AND BECOME 300-320 AT 10-14G20-24KT 18Z AND LATER. LOOKING AT THE SHORT TERM FORECAST SOUNDINGS FOR LBF...I SEE THAT WIND INCREASES SHARPLY AT THE TOP OF THE SURFACE INVERSION JUST ABOVE 2000 FEET AGL WITH SPEED CHANGE OF ABOUT 30KT AND ABOUT 30 DEGREES CHANGE IN DIRECTION. AT THIS TIME... IT APPEARS THAT THE SHEAR WILL BE HIGHER THAN THE THRESHOLD ALTITUDE OF 2000 FEET AGL AND WILL NOT BE INCLUDED IN THE TERMINAL FORECAST FOR LBF. THE TIME OF THE GREATEST RISK OF LOW LEVEL WIND SHEAR WILL BE 12-15Z. && .LBF WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION....CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
413 AM CST SAT FEB 16 2013 .UPDATE... .SHORT TERM... RAN A BLEND OF ECM...GEMREG...NAM...RUC AND HRRR FOR THE ONGOING LIGHT SNOW ASSOCIATED WITH THE WARM FRONT ACROSS WRN NEB. THIS STILL GIVES LESS THAN AN INCH ACCUMULATION BUT THE RADAR IS LOOKING PRETTY ROBUST SO WE WILL HAVE TO WAIT FOR THE SNOW TO PASS OVER AN OBSERVATION SITE. THE LATEST DETAILS ON THE WEDS-THUR STORM ARE OUT IN THE FORM OF A SPECIAL WEATHER STATEMENT. .PREV DISCUSSION... /ISSUED 337 AM CST SAT FEB 16 2013/ SHORT TERM...THROUGH 00Z MONDAY. THE GEMREG...NAM...RUC AND HRRR SHOW A DEVELOPING WARM FRONT MOVING EAST THROUGH NRN NEB THIS MORNING AND WEAKENING DURING THE AFTN. RADAR SUPPORTS THE DEVELOPMENT OF SCATTERED SNOW SHOWERS. SKIES SHOULD CLEAR OUT BEHIND THE WARM FRONT THROUGHOUT THE MORNING...AFTN AND EVENING HOURS. TEMPERATURES TODAY RANGE FROM NEAR 40 NORTHEAST TO MID 50S SOUTHWEST. LOW THROUGHOUT THE FCST AREA TONIGHT FALL TO AROUND 20. LONG TERM...00Z MONDAY AND BEYOND. MAIN FOCUS IN THE EXTENDED PERIOD REMAINS CENTERED ON THE POTENTIALLY SIGNIFICANT WINTER STORM POISED TO ARRIVE LATE WEDNESDAY LASTING INTO FRIDAY. CONFIDENCE IS INCREASING WITH THIS STORM AS THERE REMAINS STRONG SYNOPTIC AGREEMENT THROUGH THE EXTENDED PERIOD. MONDAY...BRIEF SHORTWAVE RIDGING ALOFT WILL BREAK DOWN AND BUILD EAST OF THE FORECAST AREA AS A SHORTWAVE TROUGH ADVANCED FROM THE ROCKIES ACROSS THE PLAINS. LONGER RANGE SOLUTIONS CONTINUE TO SHOW LIMITED SUPPORT FOR PRECIPITATION PRODUCTION...THUS WILL CONTINUE THE DRY FORECAST FOR NOW. THE WAVE WILL PULL A COLD FRONT ACROSS THE CWA LATE SUNDAY INTO EARLY MONDAY...WITH STRONG CAA AND A TIGHT GRADIENT TO FOLLOW...MONDAY WILL BE BLUSTERY WITH HIGHS RUNNING 15F OR MORE COOLER THAN SUNDAY AFTERNOON. INTO TUESDAY...THE OVERALL SYNOPTIC PATTERN REMAINS FAIRLY PROGRESSIVE AS SHORTWAVE RIDGING BUILDS ACROSS WESTERN NEBRASKA...HOWEVER TEMPERATURES WILL BE SLOW TO WARM TUESDAY AND WEDNESDAY HOWEVER AS EASTERLY FLOW WILL RECYCLE ARCTIC AIR BACK ACROSS MUCH OF THE CWA. SEEING A LARGE RANGE IN HIGHS FOR BOTH MONDAY AND TUESDAY...WITH 20S ACROSS NORTH CENTRAL NEBRASKA...AND POSSIBLY UPPER 30S TO LOW 40S ACROSS THE FAR SOUTHWEST. ATTENTION NOW TURNS TO THE POTENTIALLY BIG WINTER STORM FOR WEDNESDAY NIGHT AND THURSDAY. LONG RANGE SOLUTIONS CONTINUE TO ADVERTISE A STRONG UPPER LOW WHICH WILL EJECT FROM THE FOUR CORNERS REGION WEDNESDAY NIGHT INTO THE CENTRAL PLAINS BY EARLY THURSDAY. CYCLOGENESIS WILL BE ONGOING ACROSS THE EASTERN PLAINS OF COLORADO ON WEDNESDAY...WITH A RAPID DEEPENING OF THE SURFACE LOW EXPECTED. GIVEN STRONG SURFACE HIGH PRESSURE OF ~1040MB OVER THE GREAT LAKES REGION...AN INCREASING PRESSURE GRADIENT WILL DEVELOP ACROSS THE CWA...WITH THE POTENTIAL OF 25-30 MPH WIND GUSTS WEDNESDAY AND THURSDAY. THE MODELS ALSO SUGGEST PLENTIFUL MOISTURE ADVECTION IN ADVANCE OF THE SYSTEM...WITH EASTERLY UPSLOPE POSSIBLY ALLOWING FOR SNOW PRODUCTION AS EARLY AS LATE WEDNESDAY NIGHT. MEANWHILE...DOWNSTREAM OF THE UPPER TROUGH...RIDGING AND PV DESTRUCTION ACROSS THE UPPER MISSISSIPPI RIVER VALLEY WILL ALLOW THE TROUGH/CLOSED LOW TO BECOME NEGATIVELY TILTED...WITH THE PROGRESSION OF THE H5 LOW SLOWED. MODEL CONSENSUS INDICATES THE TRACK OF THE H5 LOW FROM SE COLORADO INTO NEBRASKA FROM 06Z THURSDAY THROUGH 00Z FRIDAY...PLACING MUCH OF THE FORECAST AREA UNDER A BROAD DEFORMATION BAND FOR A 12-18 HOUR PERIOD....THUS THE POTENTIAL OF A LONG SNOW EVENT IS POSSIBLE. THERE ARE A FEW DIFFERENCES WITH THE TRACK OF THE H5 LOW...MAINLY THE GFS AND ENSEMBLES ARE MORE PROGRESSIVE WITH THE TRACK OF THE LOW...CARRYING IT INTO SOUTHEASTERN NEBRASKA BY 00Z FRIDAY. THE EC WOBBLES THE H5 LOW NORTHWARD THROUGH CENTRAL NEBRASKA INTO SOUTH DAKOTA BY 06Z FRIDAY. REGARDLESS OF THE DIFFERENCES...MEAN /GFS AND EC/ QPF ACCUMULATION ARE CLOSE TO EACH OTHER /~.75 OF INCH AT KLBF/...WITH THE ENSEMBLES RUNNING SLIGHTLY HIGHER /.85/...ALL OF THIS IS EXPECTED TO FALL AS SNOW...POSSIBLY WIND DRIVEN. GIVEN THE INGREDIENTS...A MAJOR WINTER STORM IS TAKING SHAPE. AVIATION... SHORT RANGE PROJECTIONS INDICATE LIGHT SNOW OR FLURRIES MOVING INTO NORTH CENTRAL NEBRASKA BY 12Z AND ARE MOST LIKELY NORTH AND EAST OF A VTN-BBW LINE. IN THAT AREA...CEILINGS ARE LIKELY TO BE LESS THAN 1000 FEET AGL AND VISIBILITY LESS THAN 3SM. HOWEVER...AT THIS TIME...IT APPEARS THAT VTN...TIF AND BBW WILL BE ON THE WESTERN EDGE WITH CEILINGS 1000-2000 FEET AGL AND WE WILL KEEP THE INSTRUMENT CONDITIONS OUT OF THE TERMINAL FORECAST FOR VTN FOR THE TIME BEING. IN THE REST OF CENTRAL AND WESTERN NEBRASKA...CEILINGS ARE LIKELY TO BE ABOVE 3000 FEET AGL WITH NO RESTRICTIONS TO VISIBILITY. WIND IS EXPECTED TO INCREASE SATURDAY MORNING AND BECOME 300-320 AT 10-14G20-24KT 18Z AND LATER. LOOKING AT THE SHORT TERM FORECAST SOUNDINGS FOR LBF...I SEE THAT WIND INCREASES SHARPLY AT THE TOP OF THE SURFACE INVERSION JUST ABOVE 2000 FEET AGL WITH SPEED CHANGE OF ABOUT 30KT AND ABOUT 30 DEGREES CHANGE IN DIRECTION. AT THIS TIME... IT APPEARS THAT THE SHEAR WILL BE HIGHER THAN THE THRESHOLD ALTITUDE OF 2000 FEET AGL AND WILL NOT BE INCLUDED IN THE TERMINAL FORECAST FOR LBF. THE TIME OF THE GREATEST RISK OF LOW LEVEL WIND SHEAR WILL BE 12-15Z. && .LBF WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION....CDC
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1032 AM EST SAT FEB 16 2013 .SYNOPSIS... A COLD ARCTIC AIRMASS WILL FILTER INTO THE REGION TODAY WITH SOME SCATTERED LIGHT LAKE EFFECT SNOWS SOUTH OF THE LAKES. THE COLDEST AIR WILL ARRIVE ACROSS THE REGION SUNDAY AS A STRONG STORM SYSTEM MOVES ALONG THE NEW ENGLAND COAST. TEMPERATURES WILL ONLY RISE INTO THE TEENS SUNDAY. MONDAY A MODEST WARMING TREND BEGINS AHEAD OF THE NEXT STORM TO IMPACT THE AREA WITH A WINTRY MIX MONDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... THROUGH MID-MORNING...A WEAK AREA OF HIGH PRESSURE EXTENDS ACROSS EASTERN LAKE ONTARIO...WITH AN UPPER LEVEL TROF AXIS TO THE WEST ACROSS MICHIGAN. THERE ARE A COUPLE OF ILL-DEFINED FRONTAL BOUNDARIES IN THE MIX. A CONVERGENT FLOW ON LAKE ONTARIO CAN ALSO BE SEEN...PROBABLY DUE TO A LEFT OVER FRONTAL BOUNDARY...OR LAKE CONVERGENCE DUE TO THE LOCALLY WARMER TEMPERATURES. RADAR TREND SHOW AN EXPANSION OF SNOW SHOWERS ACROSS LAKE ERIE...WITH CONTINUED SNOW SHOWERS ON THE OPEN WATERS OF LAKE ONTARIO. WHILE THE LATTER IS FORECAST TO REMAIN OUT ON THE WATERS...THE APPROACHING UPPER TROF IS LIKELY TO PUSH THE SNOW SHOWERS ON LAKE ERIE ONSHORE. A CONSENSUS OF THE 12Z NAM/00Z RGEM/12Z HRRR ALL SHOW SOME LIGHT QPFS ASSOCIATED WITH THIS DURING THE AFTERNOON HOURS. BASED ON THE UPPER PATTERN...WHICH WILL SHIFT BOUNDARY LAYER WINDS TO THE WEST...THESE SOLUTIONS MAKE SENSE. BECAUSE OF THIS...WILL UP POPS TO LIKELY WEST OF ROCHESTER THIS AFTERNOON. THIS SAID...BECAUSE OF THE TRANSIENT NATURE OF THIS FEATURE...EXPECT ONLY LIGHT ACCUMULATIONS. WINDS WILL BE TOO SHEARED FOR MUCH IN THE WAY OF ORGANIZED BANDS. THERE IS SOME INDICATION BY THE HRRR THAT BRIEF PERIOD OF MODERATE SNOW SHOWERS WILL DEVELOP...BUT ITS HARD TO SAY WHERE THESE WOULD OCCUR GIVEN VARIABILITY IN MODEL RUNS. THE FAST MAJORITY OF LOCATIONS WILL GET LESS THAN AN INCH...WITH AN INCH OR TWO POSSIBLE IN HEAVIER SNOW SHOWERS. DO EXPECT A GOOD FLUFF FACTOR GIVEN 850 MB TEMPS OF -16C AS SHOWN ON OUR MORNING SOUNDING. EAST OF LAKE ONTARIO SHOULD REMAIN DRY...WITH A FAIR AMOUNT OF SUNSHINE. EXPECT HIGHS IN THE LOWER TO MID 20S IN MOST LOCATIONS. TONIGHT...THE WEAK SURFACE LOW WILL BE ABSORBED INTO THE STRENGTHENING STORM SYSTEM TRACKING NORTH OFF THE EAST COAST. AS THIS OCCURS MUCH COLDER AIR WILL ARRIVE UNDER NORTHWEST WINDS. THE CORE OF THE UPPER LEVEL TROUGH...COLD POOL ALOFT...WILL SHIFT OVER WESTERN NY. TEMPERATURES WILL PLUMMET THROUGH THE TEENS INTO THE SINGLE DIGITS MAKING FOR A VERY COLD NIGHT. WINDS WILL BE FAIRLY LIGHT SO NO THREAT FOR MUCH OF AN IMPACT FROM WIND CHILLS. THE NAM AND RGEM MODELS SHOW THAT SOME LAKE LAKE EFFECT COULD BECOME ORGANIZED EAST OF LAKE ERIE WITH NORTHWEST WINDS ALIGNING AND 850 MB TEMPS DROPPING TO AROUND -18C. ACCUMULATIONS ACROSS THE SOUTHERN TIER COULD BE IN THE TWO TO THREE INCH RANGE. ORGANIZED ACTIVITY OFF LAKE ONTARIO WILL HOLD OFF UNTIL SUNDAY. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... A WELL ALIGNED NORTHWEST OF COLDER AIR WILL SET UP ACROSS THE LOWER LAKES ON SUNDAY IN THE WAKE OF THE DEEP UPPER LEVEL TROUGH THAT WILL SLIDE EAST INTO NEW ENGLAND. WHILE THE DEEPER SYNOPTIC SCALE MOISTURE WILL SHIFT EAST INTO NEW ENGLAND...ENOUGH LOW LEVEL MOISTURE WILL REMAIN WITHIN WITH THE LAYER OF FAVORABLE SNOW GROWTH. THIS WILL RESULT IN BETTER ORGANIZED LAKE EFFECT SNOW SOUTHEAST OF BOTH LAKES. IT STILL LOOKS LIKE SNOW ACCUMULATIONS WILL STAY BELOW ADVISORY CRITERIA DUE TO THE SHORT FETCH ACROSS THE LAKES AND THE UNCERTAINTY REGARDING CONTRIBUTIONS OF MOISTURE FROM UPSTREAM LAKES. EXPECT THE HIGHEST ACCUMULATIONS TO BE ALONG THE CHAUTAUQUA RIDGE AND SOUTHEAST OF LAKE ONTARIO...FROM WAYNE TO SOUTHERN OSWEGO COUNTIES. AREAS OUTSIDE OF THE STEADIER LAKE EFFECT SNOW WILL SEE PARTLY CLOUDY SKIES WITH SOME FLURRIES. IT WILL BE RATHER COLD WITH AREAS TEMPERATURES EXPECTED TO HOLD STEADY IN THE TEENS. THE ONGOING LAKE SNOWS WILL DIMINISH SUNDAY NIGHT AS THE LOW LEVEL MOISTURE DECREASES AND THE SUBSIDENCE INVERSION CONTINUES TO LOWER. THIS WILL HAPPEN FIRST OFF LAKE ERIE...BUT THE WEAKENING LAKE ONTARIO BANDS WILL PROBABLY REMAIN INTACT THROUGH MONDAY MORNING. ON MONDAY...A WEAK SURFACE RIDGE WILL BE SANDWICHED BETWEEN LOW PRESSURE OVER THE CANADIAN MARITIMES AND A SECOND LOW THAT WILL BE ADVANCING EAST INTO THE UPPER MIDWEST. THE SOUTHERLY FLOW THAT SETS UP BETWEEN THESE TWO SYSTEMS WILL ALLOW TEMPERATURES TO REBOUND TO NEAR SEASONAL LEVELS...AFTER A COLD START TO THE DAY. ANY LAKE EFFECT SNOW SHOWERS THAT LINGER SOUTHEAST OF LAKE ONTARIO SHOULD END BY EARLY AFTERNOON. AS THE UPPER MIDWEST LOW TRACKS EAST ACROSS THE CENTRAL GREAT LAKES SUNDAY NIGHT...A POTENT LOW LEVEL JET WILL BE HEADING NORTHEAST TOWARD THE LOWER GREAT LAKES. THE LOW LEVEL JET WILL TAP INTO DEEPER MOISTURE OVER THE LOWER OHIO AND TENNESSEE VALLEYS AND ALLOW PCPN TO SPREAD EAST ACROSS OUR CWA. STRONG WARM AIR ADVECTION ALOFT ON THE NOSE OF THE LOW LEVEL JET WILL CREATE A TEMPERATURE PROFILE THAT WILL SUPPORT A WINTRY MIX OF PRECIPITATION...INCLUDING THE POSSIBILITY OF SLEET AND FREEZING RAIN. THE LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE LOW LEVEL JET AND WARMEST TEMPERATURES ALOFT WILL SHIFT EAST INTO CENTRAL AND EASTERN NEW YORK DURING THE SECOND HALF OF THE NIGHT. AS A RESULT...THE RISK FOR FREEZING RAIN MAY BE GREATER ACROSS THESE AREAS. EXPECT TEMPERATURES TO HOLD STEADY OR SLOWLY RISE MONDAY NIGHT. && .LONG TERM /TUESDAY THROUGH FRIDAY/... THE CENTRAL GREAT LAKES LOW WILL SHIFT EAST ACROSS SOUTHERN ONTARIO AND SOUTHERN QUEBEC ON TUESDAY. A PAIR OF FRONTS TRAILING SOUTH OF THE LOW WILL HAVE SOME IMPACT ON THE CWA. MIXED PCPN AT THE START OF THE DAY MAY CHANGE TO RAIN DURING THE MORNING...BEFORE COLDER AIR BUILDS IN DURING THE AFTERNOON AND CHANGES THE PCPN BACK TO SNOW. AS THE COLDER AIR DEEPENS TUESDAY NIGHT...WIDESPREAD SNOW SHOWERS WILL CONTINUE. AS FOR ANY WIND POTENTIAL...THERE IS A LOW LEVEL JET FORECAST TO MOVE INTO THE REGION...NEAR 60-70KTS. GFS BUFKIT MOMENTUM TRANSFER INDICATES A SUB-WARNING RESPONSE AS THE COLD AIR WORKS ITS WAY INTO WESTERN NY. THIS MAKES SENSE AS THE SURFACE LOW SHOULD BE NO LONGER DEEPENING AS IT MOVES WELL TO THE NORTH...WITH A ONLY A SMALL ISALLOBARIC WIND RESPONSE AS THE MAIN PRESSURE CHANGES WILL BE WELL NORTH OF THE REGION. ONCE THIS SYSTEM MOVES OUT OF THE REGION...EXPECT SCATTERED SNOW SHOWERS AND POSSIBLE STEADIER LAKE EFFECT SNOW TO CONTINUE INTO WEDNESDAY. ANOTHER RIDGE MOVES PAST ON THURSDAY FOR DRY WEATHER. THE NEXT SYSTEM ALSO APPEARS TO BE FAIRLY WELL HANDLED BY VARIOUS GUIDANCE PACKAGES. THIS SYSTEM CAN CURRENTLY BE FOUND HEADING EAST...JUST SOUTH OF THE ALEUTIAN ISLANDS ON SATELLITE IMAGERY. MODELS TAKE THIS FEATURE AND CREATE A CUTOFF OVER THE DESERT SOUTHWEST...AND THEN ACROSS THE PLAINS AND INTO THE GREAT LAKES REGION ON FRIDAY. CUTOFFS ARE NOT WELL HANDLED BY MODELS...AND OFTEN SLOWER MOVE EAST THAN MODEL FORECASTS. WILL FORECAST A CHANCE OF PRECIPITATION WITH THIS FEATURE AS IT IS SEVEN DAYS OUT...BUT IT MIGHT END UP REMAINING DRY FOR FRIDAY. && .AVIATION /16Z SATURDAY THROUGH WEDNESDAY/... THROUGH THE REMAINDER OF THE MORNING...EXPECT VFR CONDITIONS WITH SCT-BKN CIGS ABOVE 3000 FEET. AFTER THIS...AN AREA OF SNOW SHOWERS DEVELOPING ON EASTERN PORTIONS OF LAKE ERIE WILL GRADUALLY PUSH EAST AND HAVE SOME IMPACT ON THE BUF/IAG/JHW/ROC TERMINALS. ANY IMPACT SHOULD BE TEMPORARY IN NATURE...PROBABLY 1 TO 3 HOURS...BUT DURING THIS TIME VSBY BELOW 2SM IS POSSIBLE. ART SHOULD REMAIN DRY AND VFR. THIS AREA WILL DISSIPATE THIS EVENING...BUT UPSLOPE SNOW SHOWERS SHOULD EXPAND LATE TONIGHT...RESULTING IN LOWERING CIGS/VSBY SOUTH OF LAKE ONTARIO. SNOWFALL RATES SHOULD GENERALLY BE ON THE LIGHT SIDE AT MOST TAF LOCATIONS THROUGH 12Z. OUTLOOK... SUNDAY THROUGH SUNDAY NIGHT...VFR/MVFR WITH SCATTERED SNOW SHOWERS. MONDAY...VFR. TUESDAY...MVFR/IFR...RAIN CHANGING OVER TO SNOW LATE. TUESDAY NIGHT THROUGH WEDNESDAY...MVFR/LOCALIZED IFR IN LAKE EFFECT SNOW SHOWERS. && .MARINE... A COLD FRONT WILL STALL OVER THE SOUTHERN SHORE OF LAKE ONTARIO TODAY AS A WEAK SURFACE LOW TRACKS EAST ALONG THE BOUNDARY. THIS WILL WILL RESULT IN LIGHT AND VARIABLE WINDS THROUGH MUCH OF TODAY. NORTHWESTERLY WINDS WILL INCREASE SUNDAY AS COASTAL STORM SYSTEM MOVES EAST OF NEW ENGLAND. THIS WILL LIKELY BRING ANOTHER ROUND OF SMALL CRAFT ADVISORIES ALONG THE SOUTHERN LAKE ONTARIO SHORELINE. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...NONE. && $$ SYNOPSIS...SMITH NEAR TERM...APFFEL/SMITH SHORT TERM...TJP LONG TERM...TJP/ZAFF AVIATION...APFFEL/SMITH MARINE...APFFEL/SMITH
AREA FORECAST DISCUSSION
NWS BUFFALO NY
953 AM EST SAT FEB 16 2013 .SYNOPSIS... A COLD ARCTIC AIRMASS WILL FILTER INTO THE REGION TODAY WITH SOME SCATTERED LIGHT LAKE EFFECT SNOWS SOUTH OF THE LAKES. THE COLDEST AIR WILL ARRIVE ACROSS THE REGION SUNDAY AS A STRONG STORM SYSTEM MOVES ALONG THE NEW ENGLAND COAST. TEMPERATURES WILL ONLY RISE INTO THE TEENS SUNDAY. MONDAY A MODEST WARMING TREND BEGINS AHEAD OF THE NEXT STORM TO IMPACT THE AREA WITH A WINTRY MIX MONDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... THROUGH MID-MORNING...A WEAK AREA OF HIGH PRESSURE EXTENDS ACROSS EASTERN LAKE ONTARIO...WITH AN UPPER LEVEL TROF AXIS TO THE WEST ACROSS MICHIGAN. THERE ARE A COUPLE OF ILL-DEFINED FRONTAL BOUNDARIES IN THE MIX. A CONVERGENT FLOW ON LAKE ONTARIO CAN ALSO BE SEEN...PROBABLY DUE TO A LEFT OVER FRONTAL BOUNDARY...OR LAKE CONVERGENCE DUE TO THE LOCALLY WARMER TEMPERATURES. RADAR TREND SHOW AN EXPANSION OF SNOW SHOWERS ACROSS LAKE ERIE...WITH CONTINUED SNOW SHOWERS ON THE OPEN WATERS OF LAKE ONTARIO. WHILE THE LATTER IS FORECAST TO REMAIN OUT ON THE WATERS...THE APPROACHING UPPER TROF IS LIKELY TO PUSH THE SNOW SHOWERS ON LAKE ERIE ONSHORE. A CONSENSUS OF THE 12Z NAM/00Z RGEM/12Z HRRR ALL SHOW SOME LIGHT QPFS ASSOCIATED WITH THIS DURING THE AFTERNOON HOURS. BASED ON THE UPPER PATTERN...WHICH WILL SHIFT BOUNDARY LAYER WINDS TO THE WEST...THESE SOLUTIONS MAKE SENSE. BECAUSE OF THIS...WILL UP POPS TO LIKELY WEST OF ROCHESTER THIS AFTERNOON. THIS SAID...BECAUSE OF THE TRANSIENT NATURE OF THIS FEATURE...EXPECT ONLY LIGHT ACCUMULATIONS. WINDS WILL BE TOO SHEARED FOR MUCH IN THE WAY OF ORGANIZED BANDS. THERE IS SOME INDICATION BY THE HRRR THAT BRIEF PERIOD OF MODERATE SNOW SHOWERS WILL DEVELOP...BUT ITS HARD TO SAY WHERE THESE WOULD OCCUR GIVEN VARIABILITY IN MODEL RUNS. THE FAST MAJORITY OF LOCATIONS WILL GET LESS THAN AN INCH...WITH AN INCH OR TWO POSSIBLE IN HEAVIER SNOW SHOWERS. DO EXPECT A GOOD FLUFF FACTOR GIVEN 850 MB TEMPS OF -16C AS SHOWN ON OUR MORNING SOUNDING. EAST OF LAKE ONTARIO SHOULD REMAIN DRY...WITH A FAIR AMOUNT OF SUNSHINE. EXPECT HIGHS IN THE LOWER TO MID 20S IN MOST LOCATIONS. TONIGHT...THE WEAK SURFACE LOW WILL BE ABSORBED INTO THE STRENGTHENING STORM SYSTEM TRACKING NORTH OFF THE EAST COAST. AS THIS OCCURS MUCH COLDER AIR WILL ARRIVE UNDER NORTHWEST WINDS. THE CORE OF THE UPPER LEVEL TROUGH...COLD POOL ALOFT...WILL SHIFT OVER WESTERN NY. TEMPERATURES WILL PLUMMET THROUGH THE TEENS INTO THE SINGLE DIGITS MAKING FOR A VERY COLD NIGHT. WINDS WILL BE FAIRLY LIGHT SO NO THREAT FOR MUCH OF AN IMPACT FROM WIND CHILLS. THE NAM AND RGEM MODELS SHOW THAT SOME LAKE LAKE EFFECT COULD BECOME ORGANIZED EAST OF LAKE ERIE WITH NORTHWEST WINDS ALIGNING AND 850 MB TEMPS DROPPING TO AROUND -18C. ACCUMULATIONS ACROSS THE SOUTHERN TIER COULD BE IN THE TWO TO THREE INCH RANGE. ORGANIZED ACTIVITY OFF LAKE ONTARIO WILL HOLD OFF UNTIL SUNDAY. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... A WELL ALIGNED NORTHWEST OF COLDER AIR WILL SET UP ACROSS THE LOWER LAKES ON SUNDAY IN THE WAKE OF THE DEEP UPPER LEVEL TROUGH THAT WILL SLIDE EAST INTO NEW ENGLAND. WHILE THE DEEPER SYNOPTIC SCALE MOISTURE WILL SHIFT EAST INTO NEW ENGLAND...ENOUGH LOW LEVEL MOISTURE WILL REMAIN WITHIN WITH THE LAYER OF FAVORABLE SNOW GROWTH. THIS WILL RESULT IN BETTER ORGANIZED LAKE EFFECT SNOW SOUTHEAST OF BOTH LAKES. IT STILL LOOKS LIKE SNOW ACCUMULATIONS WILL STAY BELOW ADVISORY CRITERIA DUE TO THE SHORT FETCH ACROSS THE LAKES AND THE UNCERTAINTY REGARDING CONTRIBUTIONS OF MOISTURE FROM UPSTREAM LAKES. EXPECT THE HIGHEST ACCUMULATIONS TO BE ALONG THE CHAUTAUQUA RIDGE AND SOUTHEAST OF LAKE ONTARIO...FROM WAYNE TO SOUTHERN OSWEGO COUNTIES. AREAS OUTSIDE OF THE STEADIER LAKE EFFECT SNOW WILL SEE PARTLY CLOUDY SKIES WITH SOME FLURRIES. IT WILL BE RATHER COLD WITH AREAS TEMPERATURES EXPECTED TO HOLD STEADY IN THE TEENS. THE ONGOING LAKE SNOWS WILL DIMINISH SUNDAY NIGHT AS THE LOW LEVEL MOISTURE DECREASES AND THE SUBSIDENCE INVERSION CONTINUES TO LOWER. THIS WILL HAPPEN FIRST OFF LAKE ERIE...BUT THE WEAKENING LAKE ONTARIO BANDS WILL PROBABLY REMAIN INTACT THROUGH MONDAY MORNING. ON MONDAY...A WEAK SURFACE RIDGE WILL BE SANDWICHED BETWEEN LOW PRESSURE OVER THE CANADIAN MARITIMES AND A SECOND LOW THAT WILL BE ADVANCING EAST INTO THE UPPER MIDWEST. THE SOUTHERLY FLOW THAT SETS UP BETWEEN THESE TWO SYSTEMS WILL ALLOW TEMPERATURES TO REBOUND TO NEAR SEASONAL LEVELS...AFTER A COLD START TO THE DAY. ANY LAKE EFFECT SNOW SHOWERS THAT LINGER SOUTHEAST OF LAKE ONTARIO SHOULD END BY EARLY AFTERNOON. AS THE UPPER MIDWEST LOW TRACKS EAST ACROSS THE CENTRAL GREAT LAKES SUNDAY NIGHT...A POTENT LOW LEVEL JET WILL BE HEADING NORTHEAST TOWARD THE LOWER GREAT LAKES. THE LOW LEVEL JET WILL TAP INTO DEEPER MOISTURE OVER THE LOWER OHIO AND TENNESSEE VALLEYS AND ALLOW PCPN TO SPREAD EAST ACROSS OUR CWA. STRONG WARM AIR ADVECTION ALOFT ON THE NOSE OF THE LOW LEVEL JET WILL CREATE A TEMPERATURE PROFILE THAT WILL SUPPORT A WINTRY MIX OF PRECIPITATION...INCLUDING THE POSSIBILITY OF SLEET AND FREEZING RAIN. THE LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE LOW LEVEL JET AND WARMEST TEMPERATURES ALOFT WILL SHIFT EAST INTO CENTRAL AND EASTERN NEW YORK DURING THE SECOND HALF OF THE NIGHT. AS A RESULT...THE RISK FOR FREEZING RAIN MAY BE GREATER ACROSS THESE AREAS. EXPECT TEMPERATURES TO HOLD STEADY OR SLOWLY RISE MONDAY NIGHT. && .LONG TERM /TUESDAY THROUGH FRIDAY/... THE CENTRAL GREAT LAKES LOW WILL SHIFT EAST ACROSS SOUTHERN ONTARIO AND SOUTHERN QUEBEC ON TUESDAY. A PAIR OF FRONTS TRAILING SOUTH OF THE LOW WILL HAVE SOME IMPACT ON THE CWA. MIXED PCPN AT THE START OF THE DAY MAY CHANGE TO RAIN DURING THE MORNING...BEFORE COLDER AIR BUILDS IN DURING THE AFTERNOON AND CHANGES THE PCPN BACK TO SNOW. AS THE COLDER AIR DEEPENS TUESDAY NIGHT...WIDESPREAD SNOW SHOWERS WILL CONTINUE. AS FOR ANY WIND POTENTIAL...THERE IS A LOW LEVEL JET FORECAST TO MOVE INTO THE REGION...NEAR 60-70KTS. GFS BUFKIT MOMENTUM TRANSFER INDICATES A SUB-WARNING RESPONSE AS THE COLD AIR WORKS ITS WAY INTO WESTERN NY. THIS MAKES SENSE AS THE SURFACE LOW SHOULD BE NO LONGER DEEPENING AS IT MOVES WELL TO THE NORTH...WITH A ONLY A SMALL ISALLOBARIC WIND RESPONSE AS THE MAIN PRESSURE CHANGES WILL BE WELL NORTH OF THE REGION. ONCE THIS SYSTEM MOVES OUT OF THE REGION...EXPECT SCATTERED SNOW SHOWERS AND POSSIBLE STEADIER LAKE EFFECT SNOW TO CONTINUE INTO WEDNESDAY. ANOTHER RIDGE MOVES PAST ON THURSDAY FOR DRY WEATHER. THE NEXT SYSTEM ALSO APPEARS TO BE FAIRLY WELL HANDLED BY VARIOUS GUIDANCE PACKAGES. THIS SYSTEM CAN CURRENTLY BE FOUND HEADING EAST...JUST SOUTH OF THE ALEUTIAN ISLANDS ON SATELLITE IMAGERY. MODELS TAKE THIS FEATURE AND CREATE A CUTOFF OVER THE DESERT SOUTHWEST...AND THEN ACROSS THE PLAINS AND INTO THE GREAT LAKES REGION ON FRIDAY. CUTOFFS ARE NOT WELL HANDLED BY MODELS...AND OFTEN SLOWER MOVE EAST THAN MODEL FORECASTS. WILL FORECAST A CHANCE OF PRECIPITATION WITH THIS FEATURE AS IT IS SEVEN DAYS OUT...BUT IT MIGHT END UP REMAINING DRY FOR FRIDAY. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... SCT/BKN VFR CIGS PRESENT AT 12Z ACROSS THE AREA WITH SCATTERED LIGHT SNOW SHOWERS ACROSS WESTERN NY. A WEAK LOW PRESSURE AREA ARRIVING FROM NEAR GEORGIAN BAY WILL CONTINUE TO BRING SCATTERED SNOW SHOWERS ALONG WITH LIGHT AND VARIABLE WINS TROUGH MUCH OF TODAY AND INTO TONIGHT. THE WEAK LOW WILL BE ABSORBED BY A COASTAL STORM TONIGHT AND A MORE ALIGNED NORTHWEST FLOW WILL DEVELOP WITH ORGANIZED LAKE SNOWS RETURNING SOUTHEAST OF THE LAKES SUNDAY MORNING. OUTLOOK... SUNDAY THROUGH SUNDAY NIGHT...VFR/MVFR WITH SCATTERED SNOW SHOWERS. MONDAY...VFR. TUESDAY...MVFR/IFR...RAIN CHANGING OVER TO SNOW LATE. TUESDAY NIGHT THROUGH WEDNESDAY...MVFR/LOCALIZED IFR IN LAKE EFFECT SNOW SHOWERS. && .MARINE... A COLD FRONT WILL STALL OVER THE SOUTHERN SHORE OF LAKE ONTARIO TODAY AS A WEAK SURFACE LOW TRACKS EAST ALONG THE BOUNDARY. THIS WILL WILL RESULT IN WINDS WILL BECOMING LIGHT AND VARIABLE THROUGH MUCH OF TODAY. WILL CONTINUE SCA FOR THE SOUTHERN AND SOUTHEASTERN LAKE ONTARIO NEAR SHORES THROUGH MID MORNING WITH HIGHER WAVES LINGERING AFTER WINDS SUBSIDE. NORTHWESTERLY WINDS WILL INCREASE SUNDAY AS COASTAL STORM SYSTEM MOVES EAST OF NEW ENGLAND. THIS WILL LIKELY BRING ANOTHER ROUND OF SMALL CRAFT ADVISORIES ALONG THE SOUTHERN LAKE ONTARIO SHORELINE. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...NONE. && $$ SYNOPSIS...SMITH NEAR TERM...APFFEL/SMITH SHORT TERM...TJP LONG TERM...TJP/ZAFF AVIATION...SMITH MARINE...APFFEL/SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
948 AM EST SAT FEB 16 2013 .SYNOPSIS... A STRONG TROUGH ALOFT WILL PIVOT ACROSS THE SOUTHEASTERN US TODAY...AND RESULT IN RAPID CYCLOGENESIS UP THE MIDDLE ATLANTIC AND NORTHEAST COASTS TONIGHT AND SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 945 AM SATURDAY... UPDATE: REAL QUICK UPDATE TO INCLUDE EXPANSION OF WINTER WX ADVISORY FOR MOST OF CENTRAL NC...THAT NOW EXTENDS ALONG AND EAST OF A LINE FROM ALBEMARLE...TO ASHEBORO...TO GREENSBORO. ANOTHER UPDATE WILL BE ISSUED SHORTLY. ALTHOUGH IT APPEARS THAT THE SURFACE CYCLONE WILL BE DEVELOPING CLOSER TO THE COAST (NEAR MHX) THAN PREVIOUSLY ANTICIPATED AND THAT RELATIVELY MORE PRECIP WILL OCCUR ACROSS CENTRAL NC (PER LATEST RAP MODEL RUNS) IN ASSOC/W STRONG LOW-LEVEL FRONTOGENESIS 12-18Z AND THEN STRONG DPVA IN THE PRESENCE OF A DESTABILIZING AIRMASS 21-00Z...IT APPEARS THAT THE BOUNDARY LAYER WILL REMAIN TOO WARM THROUGH ~00Z THIS EVENING FOR A CHANGEOVER TO OCCUR IN MOST LOCATIONS...WITH THE COLDER AIRMASS CURRENTLY BUILDING INTO THE MID-ATLANTIC STALLING NORTH OF CENTRAL NC DUE TO VERY STRONG H5 HEIGHT FALLS IN ADVANCE OF THE APPROACHING UPPER LEVEL TROUGH...RESULTING IN BROAD PRESSURE FALLS OVER NC/VA WHICH WILL HOLD A WEAK PRESSURE TROUGH IN PLACE AND DELAY THE ARRIVAL OF THE COLDER AIRMASS FROM THE NORTH. EXPECT THE BEST CHANGEOVER POTENTIAL TO OCCUR AFTER 00Z...WHEN FORCING FOR PRECIP WILL GENERALLY BEGIN TO WANE OVER CENTRAL NC AND PRECIPITATION WILL BEGIN TO PROGRESS EAST TOWARD THE COAST. BASICALLY...THIS MAY BE YET ANOTHER CASE WHERE THE COLD AIR `CHASES` THE PRECIP...EXCEPT PERHAPS N/NE OF THE TRIANGLE WHERE FAVORABLE THERMAL PROFILES ARE MORE LIKELY TO COINCIDE WITH STRONG FORCING IN THE FORM OF LOW-LEVEL FRONTOGENESIS AND STRONG DPVA IN THE PRESENCE OF VERY STEEP (7-8C/KM) MID-LEVEL LAPSE RATES. ONE CAVEAT...GIVEN STRONG DPVA...GOOD LOW-LEVEL FRONTOGENESIS AND VERY STEEP MID-LEVEL LAPSE RATES (7-8 C/KM) IN ADVANCE OF THE APPROACHING UPPER LEVEL TROUGH...IT IS POSSIBLE THAT A QUICK BURST OF ACCUMULATING CONVECTIVE SNOW COULD OCCUR AT ABOUT THE SAME TIME AS THE COLDER AIRMASS BEGINS TO ARRIVE FROM THE NORTH ~00Z FROM GUILFORD/RANDOLPH COUNTIES EASTWARD. HOWEVER...PREVIOUS EXPERIENCE WOULD SUGGEST THAT TOO MUCH UNCERTAINTY IS PRESENT TO WARRANT EXPANDING THE ADVISORY AREA WHEN WAITING FOR A COLDER AIRMASS TO ADVECT INTO THE AREA AND WHEN RELYING PRIMARILY ON CONVECTIVE PRECIPITATION FOR ACCUMULATIONS. -VINCENT && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... AS OF 210 AM SATURDAY... BREEZY COLD CONDITIONS EARLY SUNDAY WILL PERSIST MUCH OF THE DAY. LOW LEVEL THICKNESSES SUGGEST THE COLDEST AIR WILL BE OVER THE NORTHERN AND EASTERN ZONES WHERE HIGHS WILL STRUGGLE TO REACH NEAR 40. TEMPERATURES IN THE 40S EXPECTED ACROSS THE SOUTHERN TIER NEAR THE SC BORDER. THE COLD UPPER TROUGH IS FORECAST TO BEGIN TO LIFT OUT LATE SUNDAY INTO MONDAY. HOWEVER... THE COLD SURFACE HIGH PRESSURE IS FORECAST TO BE DIRECTLY OVERHEAD SUNDAY NIGHT INTO 12Z MONDAY. THIS WILL MEAN COLD/CLEAR/CALM CONDITIONS WITH HEAVY FROST AND HARD FREEZE BY 12Z MONDAY. LOWS 18-25. WAA WILL BEGIN MONDAY... ESPECIALLY IN THE AFTERNOON. OTHER THAN A FEW HIGH CLOUDS... IT SHOULD BE MOSTLY SUNNY WITH SW WINDS 10-15 MPH. HIGHS 48 TO 55 NE TO SW. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 210 AM SATURDAY... A COUPLE OF SYSTEMS ARE EXPECTED TO BRING RAIN CHANCES TO OUR REGION THIS WEEK. THE FIRST IS FORECAST FOR TUESDAY. STRONG WARMING OUT AHEAD OF THE COLD FRONT WILL LEAD TO ALL RAIN SHOWERS. A BIT OF IN-SITU CAD MAY KEEP TEMPS DOWN IN THE PIEDMONT. QPF CONTINUES TO BE LIGHT WITH UP TO 0.25 IN THE NW WITH LESSER AMOUNTS TO THE EAST. CLOUDY WITH A 40-50 PERCENT CHANCE OF SHOWERS. HIGHS GENERALLY IN THE 45-50 RANGE NW... WITH 50S SE AFTER LOWS OF 35-42 TUESDAY. WEDNESDAY AND THURSDAY... HIGH PRESSURE SHOULD BUILD IN FROM THE NW AND NORTH WED-THU... WITH THE STRONGEST CAA EXPECTED THU. THIS MAY SET UP A STRONGER CAD EVENT FOR FRIDAY AS THE HIGH IS FORECAST TO BE IN A FAVORABLE POSITION AND STRENGTH TO INDUCE CAD AS THE NEXT SYSTEM APPROACHES FRIDAY. WED...FAIR AND SEASONABLE. LOWS IN THE 30S. HIGHS IN THE 50S. THU... MOSTLY SUNNY. LOWS 25-30. HIGHS 48-53. FRI..MOSTLY CLOUDY. A CHANCE OF RAIN. CHILLY. LOWS IN THE 30S. HIGHS IN THE 40S EXCEPT 50-55 SE. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... AS OF 635 AM SATURDAY... AFTER INITIALLY VFR CONDITIONS...THE PASSAGE OF A STRONG DEEP LAYER FRONTAL ZONE WILL RESULT IN A RAPIDLY EXPANDING...BUT NARROW... PRECIPITATION AXIS ACROSS THE WEST-CENTRAL CAROLINAS BETWEEN 12-15Z. THE PRECIPITATION AXIS WILL THEN EXPAND IN AREAL EXTENT AND PIVOT EASTWARD ACROSS CENTRAL NC THROUGH THIS EVENING...OWING TO THE AMPLIFICATION OF A STRONG TROUGH ALOFT FROM THE CENTRAL PLAINS TO THE SOUTHEAST STATES. THE PRECIPITATION WILL LIKELY BEGIN AS A MIX OF RAIN AND SNOW...BEFORE GRADUALLY TRANSITIONING TO ALL SNOW FOR THE AFTERNOON AND EVENING HOURS. CEILINGS AND VISIBILITY RESTRICTIONS WILL CONSEQUENTLY FALL INTO MVFR-IFR RANGE...BEFORE THE STEADY PRECIPITATION ENDS AND SKIES CLEAR FROM WEST TO EAST THIS EVENING. A FEW LINGERING SNOW SHOWERS WILL BE POSSIBLE THROUGH MIDNIGHT...HOWEVER...AS THE VERY COLD AND DYNAMIC TROUGH AXIS ALOFT PIVOTS EASTWARD. LOOKING AHEAD: BREEZY CONDITIONS SUNDAY...FOLLOWED BY ANOTHER FRONTAL SYSTEM AND ASSOCIATED SUB-VFR CONDITIONS AND RAIN THAT WILL AFFECT THE REGION TUE. && .RAH WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO 4 AM EST SUNDAY FOR NCZ011-027-028-042-043-078-088-089. WINTER WEATHER ADVISORY UNTIL 4 AM EST SUNDAY FOR NCZ007>010- 022>026-039>041-073>077-083>086. && $$ SYNOPSIS...MWS NEAR TERM...CBL/VINCENT SHORT TERM...BADGETT LONG TERM...BADGETT AVIATION...MWS/BADGETT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
635 AM EST SAT FEB 16 2013 .SYNOPSIS... A STRONG TROUGH ALOFT WILL PIVOT ACROSS THE SOUTHEASTERN US TODAY...AND RESULT IN RAPID CYCLOGENESIS UP THE MIDDLE ATLANTIC AND NORTHEAST COASTS TONIGHT AND SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 340 AM SATURDAY... ...PERIOD OF WINTRY WEATHER REMAINS POSSIBLE THIS EVENING INTO TONIGHT ALONG AND EAST OF HIGHWAY 1... WILL LEAVE THE CURRENT ADVISORY AS-IS. EXPECT ACCUMULATIONS 1-2" AT MOST...AND THOSE AMOUNTS ARE MOST LIKELY IN THE NE COASTAL PLAIN NEAR THE VA BORDER N/NE OF THE TRIANGLE. ALTHOUGH IT APPEARS THAT THE SURFACE CYCLONE WILL BE DEVELOPING CLOSER TO THE COAST (NEAR MHX) THAN PREVIOUSLY ANTICIPATED AND THAT RELATIVELY MORE PRECIP WILL OCCUR ACROSS CENTRAL NC (PER LATEST RAP MODEL RUNS) IN ASSOC/W STRONG LOW-LEVEL FRONTOGENESIS 12-18Z AND THEN STRONG DPVA IN THE PRESENCE OF A DESTABILIZING AIRMASS 21-00Z...IT APPEARS THAT THE BOUNDARY LAYER WILL REMAIN TOO WARM THROUGH ~00Z THIS EVENING FOR A CHANGEOVER TO OCCUR IN MOST LOCATIONS...WITH THE COLDER AIRMASS CURRENTLY BUILDING INTO THE MID-ATLANTIC STALLING NORTH OF CENTRAL NC DUE TO VERY STRONG H5 HEIGHT FALLS IN ADVANCE OF THE APPROACHING UPPER LEVEL TROUGH...RESULTING IN BROAD PRESSURE FALLS OVER NC/VA WHICH WILL HOLD A WEAK PRESSURE TROUGH IN PLACE AND DELAY THE ARRIVAL OF THE COLDER AIRMASS FROM THE NORTH. EXPECT THE BEST CHANGEOVER POTENTIAL TO OCCUR AFTER 00Z...WHEN FORCING FOR PRECIP WILL GENERALLY BEGIN TO WANE OVER CENTRAL NC AND PRECIPITATION WILL BEGIN TO PROGRESS EAST TOWARD THE COAST. BASICALLY...THIS MAY BE YET ANOTHER CASE WHERE THE COLD AIR `CHASES` THE PRECIP...EXCEPT PERHAPS N/NE OF THE TRIANGLE WHERE FAVORABLE THERMAL PROFILES ARE MORE LIKELY TO COINCIDE WITH STRONG FORCING IN THE FORM OF LOW-LEVEL FRONTOGENESIS AND STRONG DPVA IN THE PRESENCE OF VERY STEEP (7-8C/KM) MID-LEVEL LAPSE RATES. ONE CAVEAT...GIVEN STRONG DPVA...GOOD LOW-LEVEL FRONTOGENESIS AND VERY STEEP MID-LEVEL LAPSE RATES (7-8 C/KM) IN ADVANCE OF THE APPROACHING UPPER LEVEL TROUGH...IT IS POSSIBLE THAT A QUICK BURST OF ACCUMULATING CONVECTIVE SNOW COULD OCCUR AT ABOUT THE SAME TIME AS THE COLDER AIRMASS BEGINS TO ARRIVE FROM THE NORTH ~00Z FROM GUILFORD/RANDOLPH COUNTIES EASTWARD. HOWEVER...PREVIOUS EXPERIENCE WOULD SUGGEST THAT TOO MUCH UNCERTAINTY IS PRESENT TO WARRANT EXPANDING THE ADVISORY AREA WHEN WAITING FOR A COLDER AIRMASS TO ADVECT INTO THE AREA AND WHEN RELYING PRIMARILY ON CONVECTIVE PRECIPITATION FOR ACCUMULATIONS. -VINCENT && .SHORT TERM /SUNDAY THROUGH MONDAY/... AS OF 210 AM SATURDAY... BREEZY COLD CONDITIONS EARLY SUNDAY WILL PERSIST MUCH OF THE DAY. LOW LEVEL THICKNESSES SUGGEST THE COLDEST AIR WILL BE OVER THE NORTHERN AND EASTERN ZONES WHERE HIGHS WILL STRUGGLE TO REACH NEAR 40. TEMPERATURES IN THE 40S EXPECTED ACROSS THE SOUTHERN TIER NEAR THE SC BORDER. THE COLD UPPER TROUGH IS FORECAST TO BEGIN TO LIFT OUT LATE SUNDAY INTO MONDAY. HOWEVER... THE COLD SURFACE HIGH PRESSURE IS FORECAST TO BE DIRECTLY OVERHEAD SUNDAY NIGHT INTO 12Z MONDAY. THIS WILL MEAN COLD/CLEAR/CALM CONDITIONS WITH HEAVY FROST AND HARD FREEZE BY 12Z MONDAY. LOWS 18-25. WAA WILL BEGIN MONDAY... ESPECIALLY IN THE AFTERNOON. OTHER THAN A FEW HIGH CLOUDS... IT SHOULD BE MOSTLY SUNNY WITH SW WINDS 10-15 MPH. HIGHS 48 TO 55 NE TO SW. && .LONG TERM / MONDAY NIGHT THROUGH FRIDAY/... AS OF 210 AM SATURDAY... A COUPLE OF SYSTEMS ARE EXPECTED TO BRING RAIN CHANCES TO OUR REGION THIS WEEK. THE FIRST IS FORECAST FOR TUESDAY. STRONG WARMING OUT AHEAD OF THE COLD FRONT WILL LEAD TO ALL RAIN SHOWERS. A BIT OF IN-SITU CAD MAY KEEP TEMPS DOWN IN THE PIEDMONT. QPF CONTINUES TO BE LIGHT WITH UP TO 0.25 IN THE NW WITH LESSER AMOUNTS TO THE EAST. CLOUDY WITH A 40-50 PERCENT CHANCE OF SHOWERS. HIGHS GENERALLY IN THE 45-50 RANGE NW... WITH 50S SE AFTER LOWS OF 35-42 TUESDAY. WEDNESDAY AND THURSDAY... HIGH PRESSURE SHOULD BUILD IN FROM THE NW AND NORTH WED-THU... WITH THE STRONGEST CAA EXPECTED THU. THIS MAY SET UP A STRONGER CAD EVENT FOR FRIDAY AS THE HIGH IS FORECAST TO BE IN A FAVORABLE POSITION AND STRENGTH TO INDUCE CAD AS THE NEXT SYSTEM APPROACHES FRIDAY. WED...FAIR AND SEASONABLE. LOWS IN THE 30S. HIGHS IN THE 50S. THU... MOSTLY SUNNY. LOWS 25-30. HIGHS 48-53. FRI..MOSTLY CLOUDY. A CHANCE OF RAIN. CHILLY. LOWS IN THE 30S. HIGHS IN THE 40S EXCEPT 50-55 SE. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 635 AM SATURDAY... AFTER INITIALLY VFR CONDITIONS...THE PASSAGE OF A STRONG DEEP LAYER FRONTAL ZONE WILL RESULT IN A RAPIDLY EXPANDING...BUT NARROW... PRECIPITATION AXIS ACROSS THE WEST-CENTRAL CAROLINAS BETWEEN 12-15Z. THE PRECIPITATION AXIS WILL THEN EXPAND IN AREAL EXTENT AND PIVOT EASTWARD ACROSS CENTRAL NC THROUGH THIS EVENING...OWING TO THE AMPLIFICATION OF A STRONG TROUGH ALOFT FROM THE CENTRAL PLAINS TO THE SOUTHEAST STATES. THE PRECIPITATION WILL LIKELY BEGIN AS A MIX OF RAIN AND SNOW...BEFORE GRADUALLY TRANSITIONING TO ALL SNOW FOR THE AFTERNOON AND EVENING HOURS. CEILINGS AND VISIBILITY RESTRICTIONS WILL CONSEQUENTLY FALL INTO MVFR-IFR RANGE...BEFORE THE STEADY PRECIPITATION ENDS AND SKIES CLEAR FROM WEST TO EAST THIS EVENING. A FEW LINGERING SNOW SHOWERS WILL BE POSSIBLE THROUGH MIDNIGHT...HOWEVER...AS THE VERY COLD AND DYNAMIC TROUGH AXIS ALOFT PIVOTS EASTWARD. LOOKING AHEAD: BREEZY CONDITIONS SUNDAY...FOLLOWED BY ANOTHER FRONTAL SYSTEM AND ASSOCIATED SUB-VFR CONDITIONS AND RAIN THAT WILL AFFECT THE REGION TUE. && RAH WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 4 PM SATURDAY TO 4 AM EST SUNDAY FOR NCZ007>011-025>028-041>043-077-078-085-086-088-089. && $$ SYNOPSIS...MWS NEAR TERM...VINCENT SHORT TERM...BADGETT LONG TERM...BADGETT AVIATION...MWS/PWB
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
655 AM EST SAT FEB 16 2013 .SYNOPSIS... A MOIST UPPER LEVEL LOW WILL CROSS THE REGION TODAY...WITH DRY HIGH PRESSURE BUILDING IN FROM THE NORTH SUNDAY. A COLD FRONT WILL APPROACH THE CAROLINAS AND NORTHEAST GEORGIA TUESDAY WITH ANOTHER AREA OF CANADIAN HIGH PRESSURE BUILDING IN ON WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF EARLY SAT MORNING...UPPER TROUGH WILL SWING THROUGH THE REGION TODAY WITH FURTHER COLD ADVECTION AND STRONG VORT MAX ACCOMPANYING IT. VERY LIGHT PRECIP ALREADY FALLING OVER THE PIEDMONT. THIS AREA IS FAVORED BY THE NAM...GFS...RAP AND HRRR AS BEING THE FOCUS FOR THE BULK OF THE PRECIP. FORCING FROM THE WAVE WILL BE ENHANCED OVER THE PIEDMONT BY LOW LEVEL CONVERGENCE BETWEEN THE INVADING ARCTIC AIRMASS AND EXISTING COASTAL AIR. THE TROUGH STEADILY PROGRESSES EAST...WITH THE BASE HAVING DEPARTED THE CWFA BY 00Z...WITH DEEP DRY AIR RAPIDLY WORKING IN. TEMPERATURE PROFILES DO NOT INDICATE A WARM NOSE GIVEN THE ALREADY COLD AIR IN PLACE. DEEP SATURATION MEANS RAIN OR SNOW WILL MAINLY BE DETERMINED BY SURFACE TEMP. FREEZING LEVELS ARE PRETTY LOW AND SFC TEMPS WILL BE MOSTLY IN THE 30S OVER THE PIEDMONT. A RAIN/SNOW MIX WILL LIKELY TRANSITION TO SNOW AS THE FREEZING LEVEL LOWERS DUE TO THE WET BULB EFFECT. FOR QPF...SOMEWHAT TRICKY WITH OPERATIONAL MODELS SHOWING SOME POSSIBLE CONVECTIVE EFFECTS AND LOCALIZED AREAS SEEING SIGNIFICANTLY HIGHER AMOUNTS OF SNOWFALL. INDEED BOTH THE NAM AND GFS SHOW UP TO A COUPLE HUNDRED JOULES OF MUCAPE THIS AFTERNOON OVER A PORTION OF NE GA AND THE WESTERN UPSTATE. 21Z SREF BACKS THIS UP WITH LIKELY-RANGE PROBS OF 100 J. SO THIS COULD HELP ENHANCE TOTALS DURING THE EARLY TO MID AFTERNOON WHEN THE FORCING IS STRONGEST ANYWAY. CHOSE MODEST QPF DERIVED FROM A MODEL BLEND WHICH HAPPENS TO BE IN LINE WITH THE GENERAL PATTERN AND AMOUNTS OF THE LAST FEW GFS RUNS...WITH ABOUT A QUARTER INCH SOUTHEAST OF A LINE FROM GREENWOOD TO CHESTER. FAIRLY HIGH SNOW RATIOS OF 13-16 TO 1 WILL PRODUCE TOTALS GENERALLY OF 1 TO 2 INCHES TODAY. THIS MEETS OUR WINTER WX ADVY CRITERIA OVER THE SRN FOOTHILLS AND PIEDMONT OF NC AS WELL AS MOST OF THE SC PIEDMONT. IN ADDITION TO THE SYNOPTIC FORCING...PERSISTENT NORTHWEST FLOW WILL PRODUCE ENHANCED SNOWFALL IN THE UPSLOPE AREAS OF THE MOUNTAINS. NONETHELESS...TOTALS ARE COMPARABLE TO PREVIOUS FCST AND EXISTING WINTER WX ADVY WILL COVER THIS. HIGH TEMPS TODAY WILL BE WELL BELOW NORMAL IN THE ARCTIC AIR. WITH MOSTLY OVERCAST SKIES USED A BLEND OF GFS AND CMC-REGIONAL TEMPS. BOTH THE GFS AND NAM QUICKLY DRY THINGS OUT BEHIND THE DEPARTING TROUGH SO SOME BREAKS IN THE CLOUD COVER COULD COME LATE IN THE DAY ESPECIALLY SOUTHWEST...BUT PROBABLY TOO LATE TO HAVE MUCH OF AN IMPACT ON HIGHS. FURTHERMORE ANY SNOW COVER COULD LIMIT TEMPS FROM RISING. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... AS OF 300 AM SATURDAY...THE UPPER TROUGH AXIS WILL PROGRESS QUICKLY ACROSS THE REGION TONIGHT...BRINGING A QUICK END TO ANY LINGERING PRECIP. THE ONLY EXCEPTION WILL BE ACROSS THE FAR WESTERN NC MTNS... AS A MOIST NW FLOW SHOULD YIELD PERSISTENT SNOW SHOWERS THROUGH THE OVERNIGHT. THE MODELS ARE RATHER STINGY WITH QPF TONIGHT...AS THE NAM BARELY SQUEEZES OUT .05-.1 INCH ALONG THE TENN BORDER...WHILE THE GFS IS EVEN DRIER. THIS IS SOMEWHAT SURPRISING...AS THE MOIST LAYER IS PROGGED TO EXTEND TO ABOUT 800 MB THROUGH THE OVERNIGHT... WHILE H8 WINDS SHOULD BE IN THE 30-40 KT RANGE. IN ADDITION...TEMPS IN THE MOIST LAYER ARE EXPECTED TO BE EXTREMELY COOL...AS LOW AS -19 C BY 12Z SUNDAY. THEREFORE...EVEN IF THERE IS LITTLE LIQUID EQUIVALENT...THIS PATTERN IS SUGGESTIVE OF EFFICIENT SNOW PRODUCTION...WITH SNOW:LIQUID RATIOS AS HIGH AS 30:1 POSSIBLE LATE TONIGHT. THEREFORE...WE WILL FORECAST AN ADDITIONAL 1 TO 4 INCHES IN THE USUAL NW FLOW AREAS OVERNIGHT. TEMPS WILL BE VERY COOL TONIGHT THROUGH TOMORROW...EASILY 10 DEGREES BELOW CLIMO. HOWEVER...WITH HEIGHTS RISING IN THE WAKE OF THE UPPER TROUGH AXIS...THE REMAINDER OF THE SHORT TERM WILL FEATURE QUICKLY MODERATING TEMPS THAT WILL WARM VERY CLOSE TO NORMAL BY MONDAY AFTERNOON. BY THE END OF THE PERIOD...A MAJOR STORM SYSTEM WILL LIFT OUT OF THE CENTRAL PLAINS...WITH AN ATTENDANT FRONTAL BAND OF PRECIP EXPECTED TO MARCH ACROSS THE TENN VALLEY LATE MONDAY/MONDAY NIGHT. POPS WILL INCREASE QUICKLY FROM WEST TO EAST ACROSS OUR AREA LATE MONDAY NIGHT...BECOMING LIKELY ACROSS THE NC MTNS BY DAYBREAK. IT STILL APPEARS THAT PRECIP COULD BEGIN AS SNOW IN THE HIGH ELEVATIONS OF THE NC MTNS. THERE COULD ALSO BE SOME BRIEF FREEZING RAIN IN SHELTERED VALLEYS TUE MORNING...BUT THE PREDOMINANT P-TYPE SHOULD BE RAIN IN ALL AREAS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 330 AM SATURDAY...THE COLD FRONT WILL STILL BE OFF TO THE WEST BY 12Z TUE WITH A DECENT SPREAD OF LIGHT PRECIP ACROSS MOST OF THE CWFA...INCREASING EAST THROUGHOUT THE DAY. THE STRONGEST QG FORCING WILL REMAIN NORTH DURING FROPA...HOWEVER A 100 KT FINGER OF THE STJ WILL PUSH INTO MIDLANDS AND PROVIDE SOME MEASURE OF UPPER DIV SUPPORT OVER THE SRN MOST ZONES. THE FLOW BACKS DOWN THE PROFILE AND THE LLVL JET BECOMES ALIGNED PARALLEL TO THE BLUE RIDGE...THUS MECHANICAL LIFT WILL BE LIMITED. ALL THIS TO SAY THE ADDITIONAL PRECIP AMOUNTS UNTIL FROPA EARLY WED WILL BE RATHER LIGHT WITH MOST AREAS RECEIVING LESS THAN A QUARTER INCH. THERE COULD BE SOME WRAP AROUND -SNSH LINGERING ACROSS THE NRN MTNS THROUGH 06Z WED...BUT THE TREND HAS BEEN FOR LESS AND LESS AVAILABLE MOISTURE...ESP WITH THE ECMWF. IN ANY CASE...ANY AMOUNTS OF SNOW WILL BE LIGHT BTW 00Z-06Z WED. HIGH TEMPS WILL BE TRICKY WITH ALL THE CLOUDS/PRECIP...YET DECENT SW/LY FLOW...BUT MAXES A CAT OR SO BELOW NORMAL SEEMS REASONABLE PER THE LLVL THICKNESS PATTERN AND SUFFICIENT LACK OF INSOL. THE MODELS AGREE WELL WITH THE PATTERN WED THROUGH THE END OF THE PERIOD. A SHARP RIDGE AXIS WILL BUILD ACROSS THE PLAINS STATES AND PROPAGATE TOWARD THE EAST COAST THROUGH 00Z FRI. THIS WILL MAINTAIN CANADIAN HIGH PRESSURE AT THE SFC AND LOW BL THETA/E AIR WED AND THU. GOOD INSOL...BUT N/LY FLOW WILL KEEP MAXES NEAR NORMAL PERHAPS A DEGREE OR SO BELOW WED. A MODIFYING AIRMASS WITH INCREASING MID/HIGH CLOUDS THU SHOULD HOLD MAX TEMPS IN CHECK AT ABOUT 3-4 DEGREES BELOW NORMAL. ANOTHER LOW PRESSURE SYSTEM DEEPENS AND MOVES INTO THE CENTRAL MIDWEST BY THU EVENING. THE BEST UPPER DYNAMICS AGAIN WILL BE WELL NORTH OF THE CWFA BY THE TIME A COLD FRONT REACHES THE NC MTNS AROUND MID DAY FRI. THE MAIN PRECIP TYPE LOOKS TO BE ALL RAIN...WITH SOME HIGH ELEV SNOW. AGAIN...AMOUNTS LOOK TO REMAIN ON THE LOW SIDE. THERE COULD BE A DEVELOPING TRIPLE POINT LOW AND A MEASURE OF SFC/BASED SHEAR STORM DEVELOPMENT FRI AFTERNOON...BUT INSTABILITY BE A LIMITING FACTOR FOR ANY REAL STRONG/SVR CONCERN OR CONJECTURE AT THIS POINT. THE CWFA WILL LIKELY SEE A NOTICEABLE GRADIENT OF MAX TEMPS FRI AS THE LLVL THERMAL TROF EXITS TO THE NORTH AND A WARM FRONT IMPINGES UPON THE AREA FROM THE SOUTH. FOR NOW...GENERALLY THINK MAX TEMPS WILL BE A 3-5 DEGREES ABOVE NORMAL SOUTH AND ABOUT 5-8 DEGREES BELOW NORMAL NORTH OF I40. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AT KCLT...LOWERING CIG LIKELY THROUGH THE MORNING. LIGHT SHOWERS JUST BEFORE DAYBREAK HAVE BROUGHT AT LEAST BRIEF PERIODS OF MVFR CIGS TO SITES THEY PASS OVER. KCLT HAS ALREADY DONE SO ONCE AND SHOULD SEE THIS INCREASINGLY FREQUENTLY AS PRECIP BECOMES MORE WIDESPREAD...BUT AN EVENTUAL SOLID MVFR DECK WILL DEVELOP. MIDDAY PEAK IN PRECIP ACTIVITY EXPECTED AHEAD OF UPPER TROUGH PASSAGE. PRECIP WILL BEGIN AS A RAIN/SNOW MIX BUT A GRADUAL CHANGEOVER TO ALL SNOW SHOULD OCCUR...PROBABLY BY LATE MORNING. SHORT TERM GUIDANCE PRODUCES MVFR VSBY IN MOST AREAS AFFECTED BY PRECIP...SO TIED VSBY FCST TO PRECIP. CIGS LIFT TO VFR BY AFTERNOON THEN SCATTER AFTER 00Z SUN. NW WINDS THRU THE PERIOD. BIGGEST GUST POTENTIAL IS THIS EVENING AS ARCTIC AIR BLASTS IN PROMOTING MIXING. ELSEWHERE...CIGS WILL LOWER WITH INCREASING DEEP MOISTURE BY MID MORNING. INITIAL -SHRA/-SHSN WILL BRING IN AT LEAST BRIEF MVFR CIGS PRIOR TO THE WIDESPREAD LOWERING. MVFR CIGS WILL ACCOMPANY PRECIP IN THE LATE MORNING WEST TO MIDDAY EAST. RA/SN MIX WILL TRANSITION TO ALL SNOW FAIRLY QUICKLY AS FREEZING LEVELS ARE ALREADY LOW AND COLDER ARCTIC AIR WORKING IN WILL FURTHER LOWER THEM. HIGH CONFIDENCE IN AT LEAST SCATTERED PRECIP SO INCLUDED AT ALL SITES THROUGH THE AFTN. RETURN TO VFR BY LATE AFTN WITH GUSTS POSSIBLE FROM MIDDAY THROUGH THE END OF THE PERIOD AS COLD ADVECTION MAINTAINS DEEPLY MIXED SFC LAYER. NO FOG EXPECTED TONIGHT WITH THE INCOMING DRY ARCTIC AIR MASS...BUT CONTINUING UPSLOPE EFFECTS COULD PRODUCE -SHSN AND A VFR CIG IN THE MOUNTAINS NEAR THE TN BORDER. OUTLOOK...CONDITIONS WILL GENERALLY REMAIN DRY WITH VFR CONDITIONS SUNDAY. HIGH PRESSURE BUILDS OVER THE REGION EARLY NEXT WEEK. CONFIDENCE TABLE... 12-18Z 18-24Z 00-06Z 06-12Z KCLT HIGH 81% MED 65% HIGH 100% HIGH 100% KGSP MED 61% LOW 50% HIGH 100% HIGH 100% KAVL HIGH 83% MED 72% HIGH 100% HIGH 100% KHKY MED 74% MED 71% HIGH 100% HIGH 100% KGMU MED 62% LOW 51% HIGH 100% HIGH 100% KAND MED 62% MED 70% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .FIRE WEATHER... DRY AND BREEZY TO WINDY CONDITIONS ARE EXPECTED ON SUNDAY. HOWEVER...THE LOWEST RH VALUES WILL BE MID TO LATE AFTERNOON...WHILE THE WINDIEST CONDITIONS SHOULD BE IN THE MORNING THROUGH EARLY AFTERNOON. IN ADDITION...WE WILL HAVE TO WAIT AND SEE HOW MUCH PRECIPITATION FALLS OVER THE NEXT 24 TO 36 HOURS IN ORDER TO ASSESS FUEL MOISTURE CONTENT AND ASSOCIATED FIRE DANGER FOR LATE THIS WEEKEND. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...WINTER WEATHER ADVISORY UNTIL NOON EST SUNDAY FOR NCZ033- 048>052-058. WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NCZ053- 065-068>072-082-501-503-505-507>510. SC...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR SCZ002- 003-005>009-012>014. && $$ SYNOPSIS...SBK NEAR TERM...WIMBERLEY SHORT TERM...JDL LONG TERM...SBK AVIATION...WIMBERLEY FIRE WEATHER...HG
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1129 AM CST SAT FEB 16 2013 .DISCUSSION... ISSUED 1001 AM CST SAT FEB 16 2013 DEEP UPPER LOW CENTERED OVER THE GREAT LAKES CONTINUES TO BE THE PREDOMINANT WEATHER-MAKER ACROSS CENTRAL ILLINOIS TODAY. VERY COLD AIR ALOFT ASSOCIATED WITH THIS FEATURE...WITH 12Z 500MB TEMP OF -40C AT KILX. DESPITE PRESENCE OF SURFACE HIGH PRESSURE...STEEP LAPSE RATES WILL LEAD TO THE DEVELOPMENT OF SCT-BKN CU ACROSS NORTH-CENTRAL ILLINOIS THIS AFTERNOON. 13Z HRRR EVEN HINTS AT SOME CONVECTIVE SNOW-SHOWERS ALONG/NORTH OF I-74 AFTER 20Z. LATEST VISIBLE SATELLITE IMAGERY IS ALREADY SHOWING CU BEGINNING TO DEVELOP...AND UPSTREAM OBS SHOW AN AREA OF LIGHT SNOW ACROSS NORTHEAST IOWA. HAVE UPDATED THE FORECAST TO GO WITH SUNNY SKIES THIS MORNING...FOLLOWED BY PARTLY SUNNY CONDITIONS IN THE AFTERNOON. HAVE ALSO MENTIONED SCATTERED FLURRIES ALONG/NORTH OF I-74. ZONE UPDATE HAS ALREADY BEEN ISSUED. BARNES && .AVIATION... ISSUED 1129 AM CST SAT FEB 16 2013 MOSTLY CLEAR SKIES PREVAIL ACROSS CENTRAL ILLINOIS LATE THIS MORNING...HOWEVER CU-FIELD IS RAPIDLY DEVELOPING ALONG AND NORTH OF I-74. DUE TO VERY COLD AIR ALOFT AND RESULTING STEEP LAPSE RATES...EXPECT CU TO BECOME SCT-BKN AT TIMES. HAVE THEREFORE INCLUDED A TEMPO GROUP FOR LOW VFR CEILINGS AT THE I-74 TERMINALS THIS AFTERNOON. FURTHER SOUTHWEST...MOSTLY CLEAR SKIES WILL PERSIST AT BOTH KSPI AND KDEC. DIURNAL CLOUD COVER WILL DISSIPATE BY SUNSET...FOLLOWED BY MOSTLY CLEAR SKIES OVERNIGHT. HIGH CLOUDS CURRENTLY OVER THE PLAINS WILL PUSH EASTWARD SUNDAY MORNING...AS WARM FRONT APPROACHES FROM THE WEST. WINDS WILL INITIALLY BE FROM THE NORTHWEST AT AROUND 10KT THIS AFTERNOON...THEN WILL BECOME LIGHT/VARIABLE TONIGHT AS HIGH PRESSURE DRIFTS ACROSS THE AREA. ONCE THE HIGH MOVES FURTHER EAST...SOUTHEAST WINDS WILL DEVELOP ON SUNDAY. BARNES && .PREV DISCUSSION... ISSUED 330 AM CST SAT FEB 16 2013 FAIRLY QUIET WEATHER EXPECTED THIS WEEKEND AS BELOW NORMAL TEMPS THROUGH TONIGHT...MODERATE BACK ABOVE NORMAL EARLY NEXT WEEK. MORE ACTIVE WEATHER PATTERN EXPECTED DURING THE UPCOMING WORK WEEK WITH TWO FAIRLY STRONG WEATHER SYSTEMS TO IMPACT THE REGION MON AND MON NIGHT AND THU AND THU NIGHT. 00Z MODELS ARE IN GOOD AGREEMENT THROUGH EARLY NEXT WEEK WITH 1ST WEATHER SYSTEM AND THEN DIVERGE WITH HANDLING 2ND WEATHER SYSTEM LATER NEXT WORK WEEK AND WILL STAY CLOSE TO HPC/NCEP GUIDANCE. MODELS OVERALL HAVE TRENDED A BIT SLOWER WITH BOTH WX SYSTEMS AND STEERED THE FORECAST IN THAT DIRECTION WITH LOWER POPS BOTH MONDAY MORNING AND THU MORNING ESPECIALLY NE AREAS. STILL LOOKS LIKE MAINLY RAIN MONDAY AND MONDAY NIGHT WHILE MORE SNOW OR A MIXTURE OF PRECIPITATION THU AND THU NIGHT WITH ACCUMULATIONS POSSIBLE THEN. SHORT TERM...TODAY THROUGH MONDAY NIGHT STRONG UPPER LEVEL TROF REMAINS OVER EASTERN NORTH AMERICA EAST OF THE ROCKIES TODAY AND WILL SHIFT EAST OF IL LATER TONIGHT AND SUNDAY. AN EMBEDDED SHORT WAVE OVER NEBRASKA WILL TRACK SW OF IL TODAY KEEPING THE BRUNT OF ITS CLOUDS SW OF CENTRAL IL TODAY. OVERALL A PARTLY TO MOSTLY SUNNY DAY WITH MORE CLOUDS NE HALF. TEMPS ABOUT 10F BELOW NORMAL TODAY WITH UPPER 20S NE AND LOWER 30S SW. NW WINDS 10 TO 15 MPH AND GUSTS UP TO 20 MPH AGAIN TODAY. MOSTLY CLEAR SKIES TONIGHT AND LIGHTER WINDS AS HIGH PRESSURE RIDGE OVER THE CENTRAL PLAINS MOVES INTO IL BY DAWN SUNDAY. COLD LOWS OF 15 TO 20F EXPECTED TONIGHT AND COLDEST NE AREAS. TEMPS MODERATE SUNDAY AS HIGH PRESSURE RIDGE DRIFTS EAST ACROSS THE OH/TN VALLEYS WITH RETURN SE FLOW INTO IL AND MOSTLY SUNNY SKIES. HIGHS IN THE UPPER 30S NE AND LOWER 40S SW. BREEZY SOUTHERLY WINDS BY MONDAY AND BUMPED UP HIGHS A FEW MORE DEGREES IN THE UPPER 40S AND LOWER 50S. STRONG LOW PRESSURE MOVES INTO THE UPPER MS VALLEY MONDAY AND SWINGS COLD FRONT EAST THRU IL MONDAY NIGHT. THIS TO LIKELY DEVELOP SHOWERS BY MONDAY AFTERNOON AND MON EVENING AND THEN DIMINISH OVERNIGHT MONDAY NIGHT. BETWEEN A QUARTER AND HALF INCH OF RAIN OVER CENTRAL IL AND LOCALLY HIGHER AMOUNTS IN SE IL WHERE ISOLATED THUNDERSTORMS POSSIBLE SOUTH OF CHARLESTON/MATTOON MONDAY AFTERNOON AND MON EVENING. HAVE CHANCE OF LIGHT SNOW OVERNIGHT MONDAY NIGHT AS PRECIPITATION DIMINISHES BUT LITTLE OR NO ACCUMULATIONS. LONG TERM...TUESDAY THROUGH FRIDAY NIGHT QUIET WEATHER RETURNS TUE AND WED ALONG WITH COLDER TEMPS AND COLDEST ON WED AS CANADIAN HIGH PRESSURE RIDGES INTO IL WED. THEN ANOTHER LOW PRESSURE EJECTS NE INTO THE MS VALLEY BY THU NIGHT RETURNING MORE PRECIPITATION DEVELOPING DURING THE DAY THU FROM SW TO NE AND CONTINUE THU NIGHT. APPEARS COLD ENOUGH FOR SNOW THU MORNING THEN MIX OF FREEZING RAIN...SLEET AND RAIN TOO SOUTHERN AREAS THU AFTERNOON. THIS TO TRANSITION BACK TO SNOW FROM NW TO SE DURING THU NIGHT AS COLDER AIR RETURNS. COULD BE SOME SNOW ACCUMULATIONS THU AND THU NIGHT ESPECIALLY NORTH OF I-70 WITH HEAVIEST AMOUNTS NORTH OF I-72. MODELS STILL NOT IN BEST AGREEMENT WITH TRACK OF STORM SYSTEM AND OVERALL MODELS HAVE TRENDED FURTHER NORTH WITH TRACK OF SURFACE LOW NEAR CENTRAL IL LATER THU NIGHT. 07 && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1001 AM CST SAT FEB 16 2013 .DISCUSSION... ISSUED 1001 AM CST SAT FEB 16 2013 DEEP UPPER LOW CENTERED OVER THE GREAT LAKES CONTINUES TO BE THE PREDOMINANT WEATHER-MAKER ACROSS CENTRAL ILLINOIS TODAY. VERY COLD AIR ALOFT ASSOCIATED WITH THIS FEATURE...WITH 12Z 500MB TEMP OF -40C AT KILX. DESPITE PRESENCE OF SURFACE HIGH PRESSURE...STEEP LAPSE RATES WILL LEAD TO THE DEVELOPMENT OF SCT-BKN CU ACROSS NORTH-CENTRAL ILLINOIS THIS AFTERNOON. 13Z HRRR EVEN HINTS AT SOME CONVECTIVE SNOW-SHOWERS ALONG/NORTH OF I-74 AFTER 20Z. LATEST VISIBLE SATELLITE IMAGERY IS ALREADY SHOWING CU BEGINNING TO DEVELOP...AND UPSTREAM OBS SHOW AN AREA OF LIGHT SNOW ACROSS NORTHEAST IOWA. HAVE UPDATED THE FORECAST TO GO WITH SUNNY SKIES THIS MORNING...FOLLOWED BY PARTLY SUNNY CONDITIONS IN THE AFTERNOON. HAVE ALSO MENTIONED SCATTERED FLURRIES ALONG/NORTH OF I-74. ZONE UPDATE HAS ALREADY BEEN ISSUED. BARNES && .AVIATION... ISSUED 506 AM CST SAT FEB 16 2013 LITTLE CHANGE NEEDED TO PREVIOUS TAF SET. HAVE BEEN SEEING A FEW PATCHES OF CLOUDS AROUND 2500 FEET DRIFT SOUTHWARD OVER THE LAST FEW HOURS...AND THESE WILL LINGER FOR ANOTHER HOUR OR TWO. STEADY NORTHWEST WINDS AROUND 10 KNOTS TODAY WILL BECOME A BIT MORE LIGHT AND VARIABLE THIS EVENING...AS AN AXIS OF HIGH PRESSURE DRIFTS OVERHEAD. GEELHART && .PREV DISCUSSION... ISSUED 330 AM CST SAT FEB 16 2013 FAIRLY QUIET WEATHER EXPECTED THIS WEEKEND AS BELOW NORMAL TEMPS THROUGH TONIGHT...MODERATE BACK ABOVE NORMAL EARLY NEXT WEEK. MORE ACTIVE WEATHER PATTERN EXPECTED DURING THE UPCOMING WORK WEEK WITH TWO FAIRLY STRONG WEATHER SYSTEMS TO IMPACT THE REGION MON AND MON NIGHT AND THU AND THU NIGHT. 00Z MODELS ARE IN GOOD AGREEMENT THROUGH EARLY NEXT WEEK WITH 1ST WEATHER SYSTEM AND THEN DIVERGE WITH HANDLING 2ND WEATHER SYSTEM LATER NEXT WORK WEEK AND WILL STAY CLOSE TO HPC/NCEP GUIDANCE. MODELS OVERALL HAVE TRENDED A BIT SLOWER WITH BOTH WX SYSTEMS AND STEERED THE FORECAST IN THAT DIRECTION WITH LOWER POPS BOTH MONDAY MORNING AND THU MORNING ESPECIALLY NE AREAS. STILL LOOKS LIKE MAINLY RAIN MONDAY AND MONDAY NIGHT WHILE MORE SNOW OR A MIXTURE OF PRECIPITATION THU AND THU NIGHT WITH ACCUMULATIONS POSSIBLE THEN. SHORT TERM...TODAY THROUGH MONDAY NIGHT STRONG UPPER LEVEL TROF REMAINS OVER EASTERN NORTH AMERICA EAST OF THE ROCKIES TODAY AND WILL SHIFT EAST OF IL LATER TONIGHT AND SUNDAY. AN EMBEDDED SHORT WAVE OVER NEBRASKA WILL TRACK SW OF IL TODAY KEEPING THE BRUNT OF ITS CLOUDS SW OF CENTRAL IL TODAY. OVERALL A PARTLY TO MOSTLY SUNNY DAY WITH MORE CLOUDS NE HALF. TEMPS ABOUT 10F BELOW NORMAL TODAY WITH UPPER 20S NE AND LOWER 30S SW. NW WINDS 10 TO 15 MPH AND GUSTS UP TO 20 MPH AGAIN TODAY. MOSTLY CLEAR SKIES TONIGHT AND LIGHTER WINDS AS HIGH PRESSURE RIDGE OVER THE CENTRAL PLAINS MOVES INTO IL BY DAWN SUNDAY. COLD LOWS OF 15 TO 20F EXPECTED TONIGHT AND COLDEST NE AREAS. TEMPS MODERATE SUNDAY AS HIGH PRESSURE RIDGE DRIFTS EAST ACROSS THE OH/TN VALLEYS WITH RETURN SE FLOW INTO IL AND MOSTLY SUNNY SKIES. HIGHS IN THE UPPER 30S NE AND LOWER 40S SW. BREEZY SOUTHERLY WINDS BY MONDAY AND BUMPED UP HIGHS A FEW MORE DEGREES IN THE UPPER 40S AND LOWER 50S. STRONG LOW PRESSURE MOVES INTO THE UPPER MS VALLEY MONDAY AND SWINGS COLD FRONT EAST THRU IL MONDAY NIGHT. THIS TO LIKELY DEVELOP SHOWERS BY MONDAY AFTERNOON AND MON EVENING AND THEN DIMINISH OVERNIGHT MONDAY NIGHT. BETWEEN A QUARTER AND HALF INCH OF RAIN OVER CENTRAL IL AND LOCALLY HIGHER AMOUNTS IN SE IL WHERE ISOLATED THUNDERSTORMS POSSIBLE SOUTH OF CHARLESTON/MATTOON MONDAY AFTERNOON AND MON EVENING. HAVE CHANCE OF LIGHT SNOW OVERNIGHT MONDAY NIGHT AS PRECIPITATION DIMINISHES BUT LITTLE OR NO ACCUMULATIONS. LONG TERM...TUESDAY THROUGH FRIDAY NIGHT QUIET WEATHER RETURNS TUE AND WED ALONG WITH COLDER TEMPS AND COLDEST ON WED AS CANADIAN HIGH PRESSURE RIDGES INTO IL WED. THEN ANOTHER LOW PRESSURE EJECTS NE INTO THE MS VALLEY BY THU NIGHT RETURNING MORE PRECIPITATION DEVELOPING DURING THE DAY THU FROM SW TO NE AND CONTINUE THU NIGHT. APPEARS COLD ENOUGH FOR SNOW THU MORNING THEN MIX OF FREEZING RAIN...SLEET AND RAIN TOO SOUTHERN AREAS THU AFTERNOON. THIS TO TRANSITION BACK TO SNOW FROM NW TO SE DURING THU NIGHT AS COLDER AIR RETURNS. COULD BE SOME SNOW ACCUMULATIONS THU AND THU NIGHT ESPECIALLY NORTH OF I-70 WITH HEAVIEST AMOUNTS NORTH OF I-72. MODELS STILL NOT IN BEST AGREEMENT WITH TRACK OF STORM SYSTEM AND OVERALL MODELS HAVE TRENDED FURTHER NORTH WITH TRACK OF SURFACE LOW NEAR CENTRAL IL LATER THU NIGHT. 07 && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
214 PM EST SAT FEB 16 2013 .AVIATION... VARIABLE CONTS THIS AFTN WITHIN MOIST AND UNSTABLE BNDRY LYR AND EVIDENT IN OBSVD CONDS IN HEAVY SNOW SHSN AND IN RECENT KFWA METAR. XPC DIURNALLY ENHANCED ACTIVITY INLAND TO DECAY OUT BY LT AFTN W/LOSS OF HEATING. HWVR INTENSIFYING SHORE PARALLEL SINGLE BAND W/LK SUP CONNECTION SEEN TAKING SHAPE WEST OF MANISTEE DOWN TO LUNDINGTON AND POISED TO MARCH SWD THIS EVENING. IMPACTS AT KSBN APPEAR TO BE BRIEF AS BAND PIVOTS WWD TO WEST OF TERMINAL BUT GOING TO BE CLOSE. REGARDLESS A PD OF LIFR CONDS IN HEAVY SHSN LIKELY FOR A TIME THIS EVENING AND WILL AWAIT SWD EVOLUTION OF THIS BAND BFR ATTEMPTING TO TIME IT IN TAF. OTRWS CONDS IMPRVG ON SUN W/RTN OF VFR CONDS. && .UPDATE... WK BUT DISTINCT MESOLOW WHICH SPUN UP INVOF OF PARENT SFC TROUGH NR KMKG ARND 0930Z CONTS TO CURL ESE THIS MORNING AND CURRENTLY WEST OF KBTL. UPSTREAM CVRG BAND WHILE NOT AS INTENSE AS EARLIER XPCD TO REINTENSIFY THROUGH LT MORNING ALG A KBIV...KAZO...KOEB LINE AS LK AGGREGATE THERMAL TROUGHING STRENGTHENS AND UPSTREAM LK MSTR FLUX MAXIMIZES INLAND. THIS MAY NECESSITATE A EWD EXPANSION OF CURRENT ADVISORY OVR ST JOE MI TO INCLUDE BRANCH AND PERHAPS EVEN HILLSDALE. TRENDING NR TERM RUC SOLUTIONS ADVERTISE A SIMILAR EVOLUTION AND EVEN DIP FOCUSED BAND DOWN TO KTOL BY LT AFTN. HWVR GIVEN THINGS STILL IN A STATE OF FLUX WILL CONT TO MONITOR DVLPMNTS AS PLACEMENT ON LOCATION OF WRN FLANK STILL UNCERTAIN. OTRWS SIG UPSTREAM NEG THETA-E ADVTN ASSOCD/W BLDG ARCTIC RIDGING LOOKS TO STIFLE ADDNL SRN LAKE DVLPMNT UNTIL LT AFTN TIMED W/FURTHER AND MORE FVRBL LL VEERING INTO SW MI/NW IN. && .SHORT TERM... /TODAY THROUGH SUNDAY NIGHT/ PRIMARY FOCUS REMAINS ON LAKE EFFECT SNOW AMOUNTS AND IMPACTS ACROSS FAR NORTHERN INDIANA AND SOUTHWEST LOWER MICHIGAN TODAY THROUGH SUNDAY MORNING... A DIGGING UPPER TROUGH AXIS AND EMBEDDED SHORTWAVE ENERGY WILL PIVOT THROUGH THE SOUTHERN GREAT LAKES REGION THIS MORNING WITH THE CORE OF COLD AIR (7H TEMPS TO -28C) DROPPING THROUGH THIS AFTERNOON INTO TONIGHT. THIS WILL RESULT IN EXTREME OVER-LAKE INSTABILITY WITH IMPRESSIVE LAKE-7H TEMP DIFFERENTIALS NEAR 30C AND UVM/MOISTURE MAXIMIZED WITHIN THE DGZ THROUGH THE EVENT. HOWEVER...MORE WESTERLY 300 DEGREE LOW LEVEL TRAJECTORIES AND A SUBSTANTIAL DIURNAL COMPONENT TODAY WILL LIMIT ORGANIZATION (MORE CELLULAR) WITH DRY UPPER MIDWEST ENTRAINMENT AND LARGE SCALE SUBSIDENCE BEHIND THIS MORNING`S MID LEVEL WAVE ALSO LIMITING FACTORS FOR SIGNIFICANT SNOW ACCUMS. THIS DRYING/POOR FETCH COMBO COULD EVEN RESULT IN A PERIOD OF LITTLE/NO SNOW SHOWER ACTIVITY BY LATE MORNING/EARLY AFTERNOON. THIS WILL LIKELY KEEP SNOW TOTALS IN CHECK THROUGH 00Z WITH LOCATIONS NORTH OF HWY 6 IN INDIANA/MI STILL EXPECTING SNOW ACCUMS BETWEEN 1 AND 4 INCHES. ELSEWHERE...EXPECT VERY COLD CONDITIONS WITH ISOLATED TO SCATTERED SNOW SHOWERS POSSIBLE...ESPECIALLY EARLY THIS MORNING ALONG THE SYNOPTIC TROUGH WITH DUSTING TO HALF INCH TYPE ACCUMS POSSIBLE. SLIGHT IN-CLOUD VEERING TO A MORE FAVORABLE 320-330 DEGREE FETCH...LITTLE/NO SHEAR...AND FAVORABLE DIURNAL TIMING SHOULD COMBINE TO ALLOW AN INTENSE SHORE PARALLEL SNOW BAND TO MATERIALIZE WITHIN AN INTENSIFYING DIRECT THERMAL CIRCULATION/AGGREGATE SFC TROUGH TONIGHT. HI-RES GUIDANCE CONTINUES TO SUGGEST MESOLOW DEVELOPMENT WHICH WILL NO DOUBT DETERMINE WHERE THIS BAND SETS UP/PIVOTS OVERNIGHT INTO EARLY SUNDAY MORNING. INTENSE SNOWFALL RATES OF 2-3 INCHES PER HOUR WILL BE POSSIBLE WITHIN THIS BAND. QUESTIONS OBVIOUSLY AT THIS JUNCTURE REMAIN EXACTLY WHERE THIS SETS UP AND POSSIBLE INTERFERENCE (FLOW INTERRUPTION) FROM ANY MESOLOW. A 00Z MODEL CONSENSUS DOES FAVOR NORTHERN/EASTERN BERRIEN, WESTERN CASS MI, AND ST JOE INDIANA AS THE PIVOT POINT WITH THE POTENTIAL FOR SEVERAL HOURS OF HEAVY SNOW. FOR NOW WILL HOLD SERVE WITH CURRENT HEADLINES GIVEN UNCERTAINTIES. REGARDLESS THERE IS THE POTENTIAL FOR SIGNIFICANT LAKE EFFECT SNOW MAINLY LATER THIS EVENING INTO THE OVERNIGHT HOURS. ELSEWHERE...MAINLY DRY AND COLD. WAA WITH RIDGING ALOFT AND BACKING LOW LEVEL TRAJECTORIES WILL BRING ANY LINGERING LAKE EFFECT SNOW TO AN END BY EARLY SUNDAY AFTERNOON WITH NO SENSIBLE WX CONCERNS SUNDAY AFTERNOON/NIGHT. && .LONG TERM... /MONDAY THROUGH FRIDAY/ ALL IN ALL LITTLE SIG CHNG FM YDAY ANALYSIS WITH OVERALL INCRSD CONFIDENCE WRT QPF/TIMING ASSOCD WITH LOW/MODERATE AMPLITUDE NRN STREAM WAVE /CRNTLY APPROACHING PAC NW/ TO MAINTAIN PROGRESSIVE NATURE INTO ERLY NEXT WEEK. SYSTEM TRAVERSING SCNTL CAN/NRN PLAINS MONDAY TO SLOW TUESDAY/INCRSGLY VERTICALLY STACKED AS SRN END/SE CO FNTL WAVE PROCEEDS INTO OCCLUSAL IN NRN GRTLKS. SOME DISCOUNT/CAUTION TO THE MORE RAPID NAM/SREF SIGNALS...PER VARIANCE AS NOTED IN PMDHMD. AT SAME TIME DIFFICULT TO UNDERESTIMATE SHALLOW/DRY/COLD CP AIR ADVANCE AFFORDED BY POLEWARD CONNECTIVITY AT SFC/LLVLS OF SUCH INTENSE NRN MANITOBA ANTICYCLONE. ATTEMPT TO FURTHER DETAIL TIMING OF RAFL ONSET THROUGH CWA WITH SIGNALS OF DEEP MSTR/UVM HOLDING OFF TIL LATE IN DAY ONCE LATE OPEN GOMEX FEED/NRN TERMINUS OF HIGHLY INTENSE 925-8H LLJ TO 65 KTS AIMING FM MO BOOTHILL THROUGH MOUTH OF OH RVR INTO FAR SWRN IN TO DEMAND FORCED MOIST ASCENT...MOST LIKELY UNTIL LATE AFTN/21 UTC MON TIMEFRAME. RAPID EWD SHIFT OF FEATURE INTO UPR OH VLY BY 06 UTC TO GRTLY LIMIT UVM ACRS RGN AFT RAFL SLUG...WITH TRANSITION TO LIGHTER RA/SN MIX TO SN THROUGH THE NIGHT WITH LITTLE/NO ACCUMS. THEREAFTER...MINOR LES RESPONSE PER WRLY FLOW AND MUTED MIXED LYR DEPTH. ALL EYES RMN ON LATE WEEK SYSTEM. SLIGHT NWD SHIFT SFC/ALOFT NOTED PER MULTIMODEL CONSENSUS...THOUGH CERTAINLY NOT SIG ENOUGH TO DISMISS. INTMTN/SWRN STATES TROF AT APEX 00 UTC THU/F120. THEREAFTER HOLD DOUBTS AS TO EXACT TRACK. LOW AMPLITUDE/WEAKNESS NOTED IN DOWNSTREAM RIDGE THEREAFTER AS SYSTEM EJECTS FM ERN NM INTO CNTL PLAINS DY6. THIS DOWNSTREAM WEAKNESS COULD AFFORD POTNL TO BIFURCATE AND MAINTAIN A MORE EWD MOMENTUM INTO DY7. ALSO TREND TWRDS CPC 8-14 ANALOGS COULD SUGGEST A POTNL REXING OF SYSTEM PER WEAK/ANTECEDENT SRN CANADA/JAMES BAY RIDGE AIDED BY A POS HGHT ANOMOLY PHASE THEREAFTER INTO DY8. POTNL STILL HOLDS OUT AS BEST SYNOPTIC SYSTEM SINCE DEC 26 AS THU NIGHT ONSLAUGHT OF INITIAL STRONG ISENT LIFT/STRONG EVAP/STRONGER DYNAMIC COOLING PROCESSES TO ELICIT RAPID WETBULB COLLAPSE FOR SN/PSBLY BECMG HVY ACRS SWRN/WRN CWA BY ERLY FRI. THEREAFTER A DOWNSTREAM RIDGE SPLIT/REX DVLPMNT REMOTELY COULD OFFER A STALLED DEEP SYSTEM TO SLOWLY WITHER ON VINE ACRS NRN IN/SRN LWR MI...AT LEAST THROUGH HERO FCSTR EYES. LARGE STANDARD DEVIATION SPREAD PER MEDIUM RANGE MODEL ACCUMULATIONS. SAN COMPACTION WITH CLIMATOLOGICAL MEAN NEAR 14/1 RATIOS USED AFFORDED RANGES GNRLY WITHIN 3-7 INCH RANGE...FWIW AT F144-180. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...LAKE EFFECT SNOW ADVISORY UNTIL 4 AM EST /3 AM CST/ SUNDAY FOR INZ003>005. MI...LAKE EFFECT SNOW ADVISORY UNTIL 4 AM EST SUNDAY FOR MIZ079. LAKE EFFECT SNOW WARNING UNTIL 10 AM EST SUNDAY FOR MIZ077-078. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 10 AM EST SUNDAY FOR LMZ043-046. && $$ SHORT TERM...STEINWEDEL LONG TERM...MURPHY AVIATION...T UPDATE...T
AREA FORECAST DISCUSSION
NWS GOODLAND KS
350 PM MST SAT FEB 16 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 144 PM MST SAT FEB 16 2013 LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW LARGE TROUGH ACROSS WESTERN US WITH ITS AXIS CENTERED ALONG THE ROCKY MOUNTAINS...AND A LARGE SCALE TROUGH ACROSS THE EASTERN US. A SHORTWAVE TROUGH UPSTREAM OF THE H5 RIDGE IS DEEPENING OVER THE PACIFIC NW COAST. THE H5 RIDGE IS EXPECTED TO SHIFT EAST WITH A VERY DRY AIRMASS MOVING OVER OUR CWA. THE SHORTWAVE TROUGH UPSTREAM WILL DIG SOUTH TOWARDS THE GREAT BASIN OVERNIGHT AND TOWARDS THE CENTRAL ROCKIES MIDDAY. SURFACE GRADIENT WILL INCREASE AHEAD OF AN APPROACHING COLD FRONT WITH WINDS INCREASING ACROSS THE SOUTHERN HALF OF THE CWA THROUGH THE DAY. A PRE-FRONTAL TROUGH AXIS WILL MOVE INTO THE NORTHERN HALF OF THE CWA DURING THE AFTERNOON HOURS SUNDAY WITH WINDS DECREASING ALONG AND IMMEDIATELY BEHIND THIS FEATURE. WITH STRONG WAA AND DEEP MIXING EXPECTED WE ARE LIKELY TO SEE NEAR RECORD HIGH TEMPERATURES IN THE MID/UPPER 60S...POSSIBLY 70F. VERY LOW TD VALUES ARE ALSO EXPECTED BY SUNDAY AFTERNOON...WITH RH VALUES DROPPING TO RFW CRITERIA ACROSS MOST OF THE CWA DURING THE AFTERNOON. WE COULD SEE SINGLE DIGIT RH VALUES IN THE SOUTH AND WEST. AT THIS TIME...I AM MOST CONFIDENT IN WIND/RH CROSSOVER SOUTH OF I-70 WHERE I HAVE ISSUED RED FLAG WARNING. WITH THE POSSIBILITY OF WINDS DIMINISHING ACROSS THE NORTH...I AM NOT AS CONFIDENT IN WIND/RH CROSSOVER...SO I ISSUED A FIRE WEATHER WATCH ACROSS THE CENTRAL AND NORTHEASTERN PARTS OF THE CWA. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 219 PM MST SAT FEB 16 2013 LONG TERM FOCUS IS ON THE LOW PRESSURE SYSTEM MOVING EAST OF THE ROCKIES AND ACROSS THE CENTRAL HIGH PLAINS REGION WEDNESDAY NIGHT THROUGH THURSDAY NEXT WEEK. SUNDAY NIGHT A COLD FRONT MOVES THROUGH THE REGION WITH THE UPPER TROUGH MOVING THROUGH THE CENTRAL ROCKIES TO MOVE ACROSS THE CENTRAL HIGH PLAINS BY MID DAY ON MONDAY. SINCE CONDITIONS WILL BE MOSTLY DRY...EXPECT ONLY AN INCREASE IN CLOUDS AND COOLER TEMPERATURES WITHOUT ANY PRECIPITATION. HIGH TEMPERATURES WILL BE ABOUT 20 DEGREES COOLER ON MONDAY THAN THEY WERE ON SUNDAY. GUSTY NORTHWEST WINDS ARE ALSO EXPECTED DURING THE DAY BEHIND THE FRONT. SHORT WAVE RIDGING ALOFT IS EXPECTED ON TUESDAY AND TUESDAY NIGHT IN THE WAKE OF THE EXITING TROUGH AND PRIOR TO THE NEXT APPROACHING LOW PRESSURE CENTER DIVING SOUTH ALONG THE WEST COAST THAT MOVES INTO THE FAR SOUTHWEST UNITED STATES BY WEDNESDAY MORNING. A COOL HIGH PRESSURE AREA REMAINS OVER THE NORTHERN PLAINS AND EXTENDS INTO THE CENTRAL PLAINS THROUGH WEDNESDAY...TRANSPORTING LOW LEVEL MOISTURE INTO THE SOUTHERN AND CENTRAL HIGH PLAINS REGIONS WITH THE POSSIBILITY OF A LITTLE INSTABILITY MOVING OVER THE FORECAST AREA TO PRODUCE A MIX OF RAIN AND SNOW SHOWERS AND POSSIBLY EVEN A RUMBLE OF THUNDER LATE IN THE DAY ON WEDNESDAY IN THE WARM SECTOR AHEAD OF THE MAIN UPPER LOW CENTER AS IT MOVES EAST OF THE ROCKIES IN THE VICINITY OF SOUTHEAST COLORADO. HAVE LEFT THE MENTION OF THUNDER OUT FOR NOW. RAIN TRANSITIONS TO SNOW OVERNIGHT WEDNESDAY NIGHT AND EARLY THURSDAY MORNING AS COLDER AIR IS BROUGHT FURTHER SOUTH ACROSS THE HIGH PLAINS. DEPENDING UPON THE TIMING OF THE CHANGE OVER TO SNOW AND THE AMOUNT OF MOISTURE AND INSTABILITY THAT ACTUALLY AFFECTS THE FORECAST AREA...THERE IS THE POTENTIAL FOR A SIGNIFICANT SNOWFALL ACROSS THE CENTRAL HIGH PLAINS REGION MAINLY ACROSS THE NORTHEAST HALF OF THE FORECAST AREA. IT`S STILL FAR ENOUGH OUT THAT CONFIDENCE IS A LITTLE LACKING...BUT MODEL SOLUTIONS HAVE BEEN ADVERTISING REASONABLY SIMILAR SOLUTIONS THROUGH THE LATTER PORTIONS OF NEXT WEEK. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 350 PM MST SAT FEB 16 2013 VFR THROUGH THE PERIOD AT KGLD AND KMCK. W/SW WINDS UNDER 10KTS AT THE START OF THE PERIOD WILL REMAIN SO THROUGH 17Z OR SO BEFORE INCREASING AND BECOMING GUSTY FROM THE SOUTHWEST BY 19Z AND CONTINUING THROUGH 23Z OR SO. PEAK GUSTS DURING THE AFTERNOON AT KGLD AROUND 26KTS WITH 20KTS OR SO AT KMCK. LITTLE TO NO CLOUDINESS THROUGH MUCH OF THE PERIOD WITH ONLY AN INCREASE IN CIRRUS FROM THE NORTHWEST BY MID TO LATE AFTERNOON. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...RED FLAG WARNING FROM 11 AM MST /NOON CST/ TO 6 PM MST /7 PM CST/ SUNDAY FOR KSZ027>029-041-042. FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR KSZ003-004-013>016. CO...RED FLAG WARNING FROM 11 AM TO 6 PM MST SUNDAY FOR COZ254. FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR COZ253. NE...NONE. && $$ SHORT TERM...DR LONG TERM...LOCKHART AVIATION...99
AREA FORECAST DISCUSSION
NWS GOODLAND KS
242 PM MST SAT FEB 16 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 144 PM MST SAT FEB 16 2013 LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW LARGE TROUGH ACROSS WESTERN US WITH ITS AXIS CENTERED ALONG THE ROCKY MOUNTAINS...AND A LARGE SCALE TROUGH ACROSS THE EASTERN US. A SHORTWAVE TROUGH UPSTREAM OF THE H5 RIDGE IS DEEPENING OVER THE PACIFIC NW COAST. THE H5 RIDGE IS EXPECTED TO SHIFT EAST WITH A VERY DRY AIRMASS MOVING OVER OUR CWA. THE SHORTWAVE TROUGH UPSTREAM WILL DIG SOUTH TOWARDS THE GREAT BASIN OVERNIGHT AND TOWARDS THE CENTRAL ROCKIES MIDDAY. SURFACE GRADIENT WILL INCREASE AHEAD OF AN APPROACHING COLD FRONT WITH WINDS INCREASING ACROSS THE SOUTHERN HALF OF THE CWA THROUGH THE DAY. A PRE-FRONTAL TROUGH AXIS WILL MOVE INTO THE NORTHERN HALF OF THE CWA DURING THE AFTERNOON HOURS SUNDAY WITH WINDS DECREASING ALONG AND IMMEDIATELY BEHIND THIS FEATURE. WITH STRONG WAA AND DEEP MIXING EXPECTED WE ARE LIKELY TO SEE NEAR RECORD HIGH TEMPERATURES IN THE MID/UPPER 60S...POSSIBLY 70F. VERY LOW TD VALUES ARE ALSO EXPECTED BY SUNDAY AFTERNOON...WITH RH VALUES DROPPING TO RFW CRITERIA ACROSS MOST OF THE CWA DURING THE AFTERNOON. WE COULD SEE SINGLE DIGIT RH VALUES IN THE SOUTH AND WEST. AT THIS TIME...I AM MOST CONFIDENT IN WIND/RH CROSSOVER SOUTH OF I-70 WHERE I HAVE ISSUED RED FLAG WARNING. WITH THE POSSIBILITY OF WINDS DIMINISHING ACROSS THE NORTH...I AM NOT AS CONFIDENT IN WIND/RH CROSSOVER...SO I ISSUED A FIRE WEATHER WATCH ACROSS THE CENTRAL AND NORTHEASTERN PARTS OF THE CWA. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 219 PM MST SAT FEB 16 2013 LONG TERM FOCUS IS ON THE LOW PRESSURE SYSTEM MOVING EAST OF THE ROCKIES AND ACROSS THE CENTRAL HIGH PLAINS REGION WEDNESDAY NIGHT THROUGH THURSDAY NEXT WEEK. SUNDAY NIGHT A COLD FRONT MOVES THROUGH THE REGION WITH THE UPPER TROUGH MOVING THROUGH THE CENTRAL ROCKIES TO MOVE ACROSS THE CENTRAL HIGH PLAINS BY MID DAY ON MONDAY. SINCE CONDITIONS WILL BE MOSTLY DRY...EXPECT ONLY AN INCREASE IN CLOUDS AND COOLER TEMPERATURES WITHOUT ANY PRECIPITATION. HIGH TEMPERATURES WILL BE ABOUT 20 DEGREES COOLER ON MONDAY THAN THEY WERE ON SUNDAY. GUSTY NORTHWEST WINDS ARE ALSO EXPECTED DURING THE DAY BEHIND THE FRONT. SHORT WAVE RIDGING ALOFT IS EXPECTED ON TUESDAY AND TUESDAY NIGHT IN THE WAKE OF THE EXITING TROUGH AND PRIOR TO THE NEXT APPROACHING LOW PRESSURE CENTER DIVING SOUTH ALONG THE WEST COAST THAT MOVES INTO THE FAR SOUTHWEST UNITED STATES BY WEDNESDAY MORNING. A COOL HIGH PRESSURE AREA REMAINS OVER THE NORTHERN PLAINS AND EXTENDS INTO THE CENTRAL PLAINS THROUGH WEDNESDAY...TRANSPORTING LOW LEVEL MOISTURE INTO THE SOUTHERN AND CENTRAL HIGH PLAINS REGIONS WITH THE POSSIBILITY OF A LITTLE INSTABILITY MOVING OVER THE FORECAST AREA TO PRODUCE A MIX OF RAIN AND SNOW SHOWERS AND POSSIBLY EVEN A RUMBLE OF THUNDER LATE IN THE DAY ON WEDNESDAY IN THE WARM SECTOR AHEAD OF THE MAIN UPPER LOW CENTER AS IT MOVES EAST OF THE ROCKIES IN THE VICINITY OF SOUTHEAST COLORADO. HAVE LEFT THE MENTION OF THUNDER OUT FOR NOW. RAIN TRANSITIONS TO SNOW OVERNIGHT WEDNESDAY NIGHT AND EARLY THURSDAY MORNING AS COLDER AIR IS BROUGHT FURTHER SOUTH ACROSS THE HIGH PLAINS. DEPENDING UPON THE TIMING OF THE CHANGE OVER TO SNOW AND THE AMOUNT OF MOISTURE AND INSTABILITY THAT ACTUALLY AFFECTS THE FORECAST AREA...THERE IS THE POTENTIAL FOR A SIGNIFICANT SNOWFALL ACROSS THE CENTRAL HIGH PLAINS REGION MAINLY ACROSS THE NORTHEAST HALF OF THE FORECAST AREA. IT`S STILL FAR ENOUGH OUT THAT CONFIDENCE IS A LITTLE LACKING...BUT MODEL SOLUTIONS HAVE BEEN ADVERTISING REASONABLY SIMILAR SOLUTIONS THROUGH THE LATTER PORTIONS OF NEXT WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1031 AM MST SAT FEB 16 2013 VFR CONDITIONS WILL PERSIST THROUGH THE TAF PERIOD AT GLD AND MCK. A FEW MID TO HIGH LEVEL CLOUDS /AROUND 10KFT AGL/ WILL DEVELOP THIS AFTERNOON BUT OTHERWISE SKIES WILL BE CLEAR THROUGH THE FORECAST PERIOD. BREEZY NORTHWEST WINDS THIS AFTERNOON /20KTS GUSTING TO NEAR 30KTS/ WILL DECREASE THIS EVENING...BECOMING LIGHT AND VARIABLE THOUGH GENERALLY OUT OF THE WEST. EARLY TOMORROW WINDS WILL BE LIGHT OUT OF THE SOUTHWEST AS A SURFACE THROUGH SETS UP NEAR THE KANSAS- COLORADO BORDER. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...RED FLAG WARNING FROM 11 AM MST /NOON CST/ TO 6 PM MST /7 PM CST/ SUNDAY FOR KSZ027>029-041-042. FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR KSZ003-004-013>016. CO...RED FLAG WARNING FROM 11 AM TO 6 PM MST SUNDAY FOR COZ254. FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR COZ253. NE...NONE. && $$ SHORT TERM...DR LONG TERM...LOCKHART AVIATION...JJM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
145 PM MST SAT FEB 16 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 144 PM MST SAT FEB 16 2013 LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOW LARGE TROUGH ACROSS WESTERN US WITH ITS AXIS CENTERED ALONG THE ROCKY MOUNTAINS...AND A LARGE SCALE TROUGH ACROSS THE EASTERN US. A SHORTWAVE TROUGH UPSTREAM OF THE H5 RIDGE IS DEEPENING OVER THE PACIFIC NW COAST. THE H5 RIDGE IS EXPECTED TO SHIFT EAST WITH A VERY DRY AIRMASS MOVING OVER OUR CWA. THE SHORTWAVE TROUGH UPSTREAM WILL DIG SOUTH TOWARDS THE GREAT BASIN OVERNIGHT AND TOWARDS THE CENTRAL ROCKIES MIDDAY. SURFACE GRADIENT WILL INCREASE AHEAD OF AN APPROACHING COLD FRONT WITH WINDS INCREASING ACROSS THE SOUTHERN HALF OF THE CWA THROUGH THE DAY. A PRE-FRONTAL TROUGH AXIS WILL MOVE INTO THE NORTHERN HALF OF THE CWA DURING THE AFTERNOON HOURS SUNDAY WITH WINDS DECREASING ALONG AND IMMEDIATELY BEHIND THIS FEATURE. WITH STRONG WAA AND DEEP MIXING EXPECTED WE ARE LIKELY TO SEE NEAR RECORD HIGH TEMPERATURES IN THE MID/UPPER 60S...POSSIBLY 70F. VERY LOW TD VALUES ARE ALSO EXPECTED BY SUNDAY AFTERNOON...WITH RH VALUES DROPPING TO RFW CRITERIA ACROSS MOST OF THE CWA DURING THE AFTERNOON. WE COULD SEE SINGLE DIGIT RH VALUES IN THE SOUTH AND WEST. AT THIS TIME...I AM MOST CONFIDENT IN WIND/RH CROSSOVER SOUTH OF I-70 WHERE I HAVE ISSUED RED FLAG WARNING. WITH THE POSSIBILITY OF WINDS DIMINISHING ACROSS THE NORTH...I AM NOT AS CONFIDENT IN WIND/RH CROSSOVER...SO I ISSUED A FIRE WEATHER WATCH ACROSS THE CENTRAL AND NORTHEASTERN PARTS OF THE CWA. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 241 AM MST SAT FEB 16 2013 SUNDAY NIGHT-MONDAY NIGHT...LARGE SCALE FORCING FOR ASCENT WILL INCREASE SHARPLY OVERNIGHT SUNDAY AS STRONG FRONTAL CIRCULATION EXPECTED BEHIND THE SFC FRONT AND COINCIDES WELL WITH STRONGEST DIV Q AND PV ADVECTION ACROSS MUCH OF THE CWA. THETA E LAPSE RATES DO INDICATE CONDITIONAL INSTABILITY WILL BE PRESENT AT THIS TIME...BUT GIVEN T-TD DEPRESSIONS OF AIR MASS IN ADVANCE OF THIS SYSTEM MAKE ME DOUBTFUL THAT WIDESPREAD SATURATION WILL DEVELOP TO TAKE ADVANTAGE OF POTENTIAL INSTABILITY. WILL KEEP POPS IN THE 5-10 PERCENT RANGE UNTIL MORE CONFIDENT ABOUT POTENTIAL SATURATION IN THE H7-H5 LAYER SUNDAY NIGHT AND MONDAY MORNING. PERIOD OF SUBSIDENCE WILL DEVELOP BEHIND THIS SYSTEM AND WHILE THERE WILL BE A PERIOD OF STRONG FRONTOGENESIS LINGERING ACROSS THE AREA...DO NOT THINK FORCED ASCENT WILL BE STRONG ENOUGH TO PRODUCE ANY MEANINGFUL PRECIPITATION. TUESDAY THROUGH FRIDAY...AN UPPER LEVEL RIDGE WILL START OUT THE PERIOD ON TUESDAY WITH A BACKDOOR COLD FRONT MOVING IN DURING THE NIGHT. WEDNESDAY AN UPPER LEVEL LONG WAVE TROUGH WILL APPROACH THE TRI-STATE AREA. DURING THE DAY THE 850-700MB LAYER SATURATES AND STRONG ISENTROPIC LIFT DEVELOPS OVER THE AREA AHEAD OF THE LONG WAVE TROUGH. WITH TEMPERATURES BELOW FREEZING FOR MUCH OF THE AREA...FREEZING DRIZZLE MAY DEVELOP. WILL ONLY MENTION A RAIN/SNOW MIX AT THIS TIME RANGE INSTEAD. WEDNESDAY NIGHT COOLER AIR MOVES IN AS THE UPPER LEVEL TROUGH MOVES CLOSER TO THE AREA CAUSING THE PRECIPITATION TO CHANGE TO SNOW BY THE OVERNIGHT HOURS. DURING THE OVERNIGHT HOURS THE UPPER LEVEL TROUGH AND SURFACE LOW MOVE OVER THE AREA...CAUSING THE LIFT TO PEAK. WILL LIKELY SEE THE MOST SNOWFALL OCCUR LATE WEDNESDAY NIGHT THROUGH EARLY THURSDAY MORNING AS THE SURFACE LOW AND UPPER LEVEL TROUGH MOVE ACROSS THE AREA. THURSDAY MORNING A STRONG COLD FRONT MOVES IN BEHIND THE SURFACE LOW AS IT MOVES EAST. BEHIND THE FRONT NORTHWEST WINDS WILL QUICKLY STRENGTHEN. MEANWHILE SNOWFALL WILL TAPER OFF FROM WEST TO EAST AS THE WINTER STORM SYSTEM MOVES OUT OF THE AREA...COMING TO AN END BY THE OVERNIGHT HOURS. CURRENTLY LOOKS LIKE THE WINDS WILL STRENGTHEN AS THE SNOWFALL BEGINS TO WIND DOWN WHICH WILL HELP REDUCE THE IMPACTS OF THE STORM. FRIDAY LOOKS DRY AS A SHORT WAVE RIDGE MOVES OVER THE AREA AHEAD OF THE NEXT UPPER LEVEL TROUGH MOVING ACROSS THE DESERT SOUTHWEST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1031 AM MST SAT FEB 16 2013 VFR CONDITIONS WILL PERSIST THROUGH THE TAF PERIOD AT GLD AND MCK. A FEW MID TO HIGH LEVEL CLOUDS /AROUND 10KFT AGL/ WILL DEVELOP THIS AFTERNOON BUT OTHERWISE SKIES WILL BE CLEAR THROUGH THE FORECAST PERIOD. BREEZY NORTHWEST WINDS THIS AFTERNOON /20KTS GUSTING TO NEAR 30KTS/ WILL DECREASE THIS EVENING...BECOMING LIGHT AND VARIABLE THOUGH GENERALLY OUT OF THE WEST. EARLY TOMORROW WINDS WILL BE LIGHT OUT OF THE SOUTHWEST AS A SURFACE THROUGH SETS UP NEAR THE KANSAS- COLORADO BORDER. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...RED FLAG WARNING FROM 11 AM MST /NOON CST/ TO 6 PM MST /7 PM CST/ SUNDAY FOR KSZ027>029-041-042. FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR KSZ003-004-013>016. CO...RED FLAG WARNING FROM 11 AM TO 6 PM MST SUNDAY FOR COZ254. FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR COZ253. NE...NONE. && $$ SHORT TERM...DR LONG TERM...JRM/JTL AVIATION...JJM
AREA FORECAST DISCUSSION
NWS JACKSON KY
103 PM EST SAT FEB 16 2013 .UPDATE... ISSUED AT 103 PM EST SAT FEB 16 2013 SCATTERED SNOW SHOWERS ARE PRESENTLY RAMPING UP AS THE SHORTWAVE ENERGY DIVES SOUTHEAST INTO EASTERN KENTUCKY. HRRR SEEMS TO HAVE A PRETTY GOOD HANDLE ON THINGS THIS AFTERNOON AND SHOWS A SUBSTANTIAL WEAKENING TREND AROUND SUNSET THIS EVENING AS WE WOULD EXPECT. THUS...GOING TO KEEP THE HIGHEST POPS IN THE NEXT 2 TO 4 HOURS...THEN TRAIL THINGS BACK TO FLURRIES TONIGHT. BASED ON THE LACK OF ACTIVITY UPSTREAM...THE ONLY SUPPORT FOR ANY ACTIVITY TONIGHT WILL BE UPSLOPE FLOW INTO THE HIGHER TERRAIN. MADE SOME ADJUSTMENTS TO TIMING AND TRENDS...BUT NO FORECAST UPDATE IS NEEDED AT THIS TIME. UPDATE ISSUED AT 950 AM EST SAT FEB 16 2013 STILL DEALING WITH SOME FLURRIES NEAR THE VIRGINIA BORDER...WHICH REMAINS COVERED WITH ONGOING FORECAST. OTHERWISE...LATEST HI RES MODEL GUIDANCE SUGGEST A SLIGHTLY SLOWER ONSET OF SNOW SHOWER ACTIVITY THIS AFTERNOON...SO HAVE SLOWED THINGS DOWN A BIT. SNOW ACCUMULATIONS WILL BE HARD TO COME BY GIVEN SURFACE TEMPERATURES NEAR FREEZING. THE EXCEPTION WILL BE IN THE HIGH TERRAIN NEAR THE VIRGINIA BORDER WHERE UP TO A HALF INCH OF SNOW MAY BE POSSIBLE. OUTSIDE OF THESE MINOR CHANGES...FORECAST IS IN GOOD SHAPE. UPDATE ISSUED AT 740 AM EST SAT FEB 16 2013 GRIDS WERE UPDATED BASED ON THE LATEST TEMPERATURE AND DEWPOINT TRENDS. FLURRIES WERE ALSO PUT IN IN THE WEATHER GRIDS INITIALLY NEAR THE VA BORDER PER RADAR IMAGERY AND COOP REPORTS. OTHERWISE...THE FORECAST FOR TODAY STILL REMAINS ON TARGET. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 355 AM EST SAT FEB 16 2013 BEHIND A COLD FRONT THAT CROSSED THE REGION ON FRI EVENING...THE REGION REMAINS IN NW TO NORTHERLY FLOW IN THE LOW LEVELS AND UNDER THE INFLUENCE OF A DEEPENING TROUGH OVER THE EASTERN CONUS. LOW LEVEL MOISTURE IS RATHER LIMITED...BUT RADAR RETURNS HINT THAT SOME FLURRIES MAY BE FALLING FROM THE STRATOCU OVER THE BIG SANDY REGION AND NEAR THE VA BORDER. A FEW FLURRIES HAVE BEEN INSERTED IN THE GRIDS PRIOR TO DAWN OVER THE SOUTHEASTERN CWA IN LINE WITH RECENT RADAR TRENDS. OTHERWISE...A SHORTWAVE TROUGH WORKING THROUGH AN EASTERN CONUS TROUGH WILL APPROACH THE REGION TODAY...BRINGING A BIT OF MOISTURE WITH IT...BUT AS NOTED BY THE PREVIOUS FORECASTER...MOISTURE WILL BE RATHER SHALLOW. HOWEVER...WITH THE APPROACH OF THE SHORTWAVE TROUGH...COLD AIR ADVECTION SHOULD LEAD TO STEEPENING LAPSE RATES...AND THE GENERAL MODEL CONSENSUS IS FOR A PERIOD OF SCATTERED SNOW SHOWERS FROM AROUND MIDDAY THROUGH EARLY EVENING. BEFORE AND AFTER THIS POINT...FLURRIES OR ISOLATED SNOW SHOWERS WILL BE POSSIBLE. A COUPLE OF ADDITIONAL DISTURBANCES AND LINGERING NORTHWEST UPSLOPE FLOW WILL LEAD TO A THREAT OF A BIT BETTER COVERAGE OF SNOW SHOWERS OVER THE EASTERN CWA AND NEAR THE VA BORDER DURING MID TO LATE EVENING AND POSSIBLY TOWARD DAWN ON SUNDAY. ANY SNOW THAT FALLS WILL HAVE A HIGH SNOW TO LIQUID RATIO PERHAPS AS HIGH AS 20 TO 1...BUT INCREASING SUN ANGLE AND TEMPS NEARING THE FREEZING MARK SHOULD KEEP ACCUMULATIONS RATHER MINIMAL IN THE LOWER ELEVATIONS BELOW 1500 FEET TO A BRIEF DUSTING OR COATING OF SNOW. AT 1500 FEET OR ABOVE AS MUCH AS A HALF OF AN INCH COULD OCCUR AND ABOVE 2000 FEET AN INCH TO LOCALLY MORE ABOVE 3000 FEET CANNOT BE RULED OUT FROM THIS. MOISTURE SHOULD BECOME SHALLOWER BY SUN MORNING AND THIS COMBINED WITH TEMPS STARTING TO WARM SHOULD END THE THREAT FOR ANY FLURRIES BY MIDDAY ON SUNDAY. HOWEVER...STRATOCU MAY LINGER LONGER THAN SUGGEST BY THE 0Z GFS...POSSIBLY INTO THE AFTERNOON AS SUGGESTED BY THE 6Z NAM. FOR THIS FORECAST...HELD ONTO THE THREAT OF FLURRIES INTO THE DAY ON SUN IN THE SOUTHEAST AND WENT MORE PESSIMISTIC ON TIMING OF THE CLEARING ON SUN AS WELL. AS FOR TEMPERATURES...COLD AIR ADVECTION SHOULD LEAD TO MIN T LIKELY AFTER SUNRISE THIS MORNING AND MAX T SHOULD BE MORE ON THE ORDER OF THE 3 HOURLY TEMPS IN THE MOS GUIDANCE AND A FEW DEGREES BELOW MOS GUIDANCE MAX T. THE PREVIOUS FORECAST MAX T ALREADY HAD THIS IDEA...SO VERY LITTLE CHANGE WAS MADE. MIN T TONIGHT WERE NOT CHANGED MUCH FROM THE PREVIOUS FORECAST EITHER AND THEY SHOULD BE ON THE ORDER OF 10 DEGREES BELOW NORMAL. 850 MB TEMPS WILL BE -10C TO -15C WELL INTO THE DAY ON SUN AND MAX T WILL BE SIMILAR TO SAT...ESPECIALLY IN THE CENTRAL AND EASTERN CWA WHERE STRATOCU SHOULD BE MOST PERSISTENT. IF THE LOW CLOUDS LINGER AS THE 6Z NAM SUGGESTS IN THE CENTRAL AND EAST THEN MAX T MIGHT NOT REACH THE FREEZING MARK IN MANY LOCATIONS IN THE EASTERN PART OF THE CWA. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 358 AM EST SAT FEB 16 2013 THE MODELS REMAIN IN GOOD AGREEMENT WITH A PROGRESSIVE BUT FAIRLY AMPLIFIED PATTERN TO CONTROL ACROSS THE CONUS THROUGH THE LONG TERM. A DEPARTING DEEP UPPER LEVEL LOW WILL START OUT ACROSS NEW ENGLAND...WITH THE OHIO AND TENNESSEE VALLEYS ENJOYING A BRIEF DRY SPELL THANKS TO A TRANSIENT UPPER LEVEL RIDGE. TEMPERATURES WILL RETURN TO ABOVE NORMAL FOR MONDAY...WITH GUIDANCE TRENDING A BIT WARMER STILL...WITH HIGHS INTO THE MID 50S. A SHORT WAVE TROUGH WILL THEN DIG ACROSS THE NORTHERN PLAINS AND THE NORTHERN GREAT LAKES REGION THROUGH TUESDAY...ESCORTING A COLD FRONT THROUGH EASTERN KENTUCKY MONDAY NIGHT INTO EARLY TUESDAY MORNING. THERE ARE STILL SOME TIMING DIFFERENCES WITH THE FRONT...WITH THE ECMWF REMAINING THE SLOWEST AND THE MAJORITY OF THE REMAINING GUIDANCE MORE PROGRESSIVE. AS SUCH...HAVE CONTINUED TO CENTER THE HIGHEST POPS DURING THE OVERNIGHT PERIOD ON MONDAY NIGHT AND THEN SIDED WITH THE BLENDED GUIDANCE WITH POPS DECREASING RAPIDLY FROM WEST TO EAST TOWARDS 12Z TUESDAY. RIDGING WILL BRING MORE DRY WEATHER TO THE AREA FROM TUESDAY AFTERNOON THROUGH AT LEAST THURSDAY MORNING...ALTHOUGH WITH THE SURFACE HIGH CENTERED TO THE NORTH...TEMPERATURES WILL REMAIN BELOW NORMAL...WITH HIGHS RETREATING TO THE LOW AND MID 40S. BY THURSDAY...THE NEXT SYSTEM TAKES AIM AT THE AREA...THIS TIME OUT OF THE CENTRAL PLAINS...WITH A WARM FRONT THREATENING OUR AREA WITH OVERRUNNING PRECIPITATION BY LATE THURSDAY AFTERNOON. THE MODELS HAVE GENERALLY TRENDED SLOWER WITH THIS SYSTEM COMPARED TO 24 HOURS AGO...ESPECIALLY THE GFS. AS SUCH...HAVE KEPT THE MAIN SHOT OF THE RAIN RESERVED FOR THURSDAY NIGHT...ALIGNING CLOSE TO THE BLENDED GUIDANCE OUTPUT. BY FRIDAY...SOME SHOWERS MAY LINGER IN THE MORNING...WITH IMPROVING CONDITIONS BY AFTERNOON AND TEMPERATURES RETURNING TO ABOVE NORMAL READINGS IN THE 50S UNDER FAIRLY BRISK SOUTHWEST WINDS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 103 PM EST SAT FEB 16 2013 A WEAK DISTURBANCE WILL BRING GRADUALLY LOWERING CEILINGS INTO EASTERN KENTUCKY TODAY INTO THIS EVENING. HOWEVER...IT LOOKS LIKE THE WORSE CONDITIONS EXPECTED WILL BE 2500 FOOT MVFR CIGS. SOME QUESTION AS TO HOW LONG THE LOWER CIGS MAY PLAGUE THE AREA AS THERE IS QUITE A BIT OF DRY AND CLEARING UPSTREAM. THUS...AFTER THIS EVENING...SKY FORECAST TONIGHT REMAINS VERY UNCERTAIN. SNOW SHOWER ACTIVITY THIS AFTERNOON WILL TRAIL OFF TO FLURRIES TONIGHT. COULD BE A FEW STRONG WIND GUST OUT OF THE WEST-NORTHWEST TODAY...WITH STEADY WEST- NORTHWEST WINDS CONTINUING THROUGH TONIGHT. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KAS SHORT TERM...JP LONG TERM...GEOGERIAN AVIATION...KAS
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
352 PM EST SAT FEB 16 2013 .SHORT TERM...THIS AFTERNOON AND TONIGHT UPPER LEVEL WAVE AND MID LEVEL COLD POOL HAVE BROUGHT SEVERAL SNOW SQUALLS TO SOUTHEAST MICHIGAN TODAY...DROPPING A QUICK 1 TO 2 INCHES OF SNOW ACROSS AREAS ALONG AND SOUTH OF THE INTERSTATE 69 CORRIDOR. HOWEVER THE SURFACE TROUGH AND PV ANOMALY HAVE YET TO TRACK THROUGH SOUTHEAST MICHIGAN. THESE FEATURES WILL TRACK THROUGH DURING THE EVENING HOURS AND TURN WINDS TO A NORTHERLY DIRECTION...BRINGING COOLER AIR AND LAKE MOISTURE IN FROM LAKE HURON. ALTHOUGH THE DTX HIRES WRF RUNS DEVELOP AN IMPRESSIVE LAKE EFFECT BAND THAT TRACKS THROUGH THE THUMB REGION BETWEEN 21Z AND 06Z...MODEL INITIALIZATION IS VERY POOR AS THE 20Z PANEL INDICATES THERE SHOULD BE AN IMPRESSIVE BAND JUST OFFSHORE OF HURON COUNTY...WHICH BY THE VISIBLE SATELLITE IMAGERY IS FAR FROM REALITY. THIS FAILURE IN THE MODEL LOOKS TO BE THE FAILURE OF A MESOLOW TO DEVELOP ACROSS CENTRAL LAKE HURON...INSTEAD THE LAKE EFFECT IS IN A NORTHWEST TO SOUTHEAST ORIENTATION BEHIND THE MAIN SURFACE TROUGH. THIS IS ACTUALLY DEPICTED RATHER WELL BY THE HRRR MODEL WHICH BRINGS THIS FEATURE SOUTH THROUGH THE EARLY EVENING HOURS AND DEVELOPS A NORTH-SOUTH BAND OF LAKE EFFECT SNOW ACROSS THE EASTERN THUMB WITH SIGNIFICANT ASSISTANCE FROM CONVERGENCE AS NORTH-NORTHWEST WINDS OVER THE LAKE CONVERGE WITH NORTHEASTERLY WINDS ACROSS SOUTHERN LAKE HURON. THIS SETUP WOULD BRING SEVERAL INCHES OF ACCUMULATING SNOW TO SANILAC AND ST. CLAIR COUNTIES DURING THE EVENING HOURS UNTIL LAKE WINDS TURN MORE NORTHERLY AND CONVERGENCE ALONG THE LAKE BECOMES BROADER. TO ADD TO THE CONFUSION THE NAM MODEL IS VERY BRIEF WITH THE CONVERGENCE AND KEEPS MOST OF THE LAKE EFFECT SNOW OFFSHORE DURING THE EVENING HOURS. GIVEN THE GOOD INITIALIZATION INCLINATION IS TO LEAN TOWARDS THE HRRR SOLUTION AS EAST-WEST BANDS TEND TO TRANSITION TO NORTH-SOUTH AS THEY ENCOUNTER THE TOPOGRAPHY OF THE THUMB REGION...HOWEVER CANNOT RULE OUT THE POSSIBILITY OF A MESOLOW FORMING AND TRACKING FARTHER INLAND THAN SANILAC AND ST. CLAIR COUNTIES. THEREFORE WILL HANG ONTO THE WINTER WEATHER ADVISORY FOR THE THUMB REGION AND LET LATER SHIFTS PARE DOWN THE HEADLINE AS THE NATURE AND ORIENTATION OF THE LAKE EFFECT BECOME APPARENT DURING THE EVENING HOURS. THE PREVIOUS FORECAST AMOUNTS STILL LOOK SOLID IN THIS REGION WITH A GOOD 2 TO 4 INCHES EXPECTED WITH ISOLATED 6 INCH AMOUNTS NEAR THE LAKE HURON SHORELINE AREAS. && .LONG TERM...SUNDAY THROUGH FRIDAY VERY STRONG NEGATIVE POTENTIAL VORTICITY ADVECTION FROM RETREATING LARGE WAVELENGTH UPPER LEVEL TROUGH WILL LEAD TO RAPID 1000-500MB GEOPOTENTIAL HIGH RISES OVER SOUTHEASTERN MICHIGAN 12-00Z SUNDAY. THE MAXIMUM OF GEOPOTENTIAL HEIGHT RISES WILL REMAIN OVER THE SOUTHERN APPALACHIANS IN RESPONSE TO THE BOMBING NOR`EASTER...HOWEVER...HEIGHT RISE RIDGE AXIS WILL EXTEND NORTHWARD INTO CENTRAL GREAT LAKES. REMNANT LAKE EFFECT WILL BE ONGOING OVER SOUTH LAKE HURON THROUGH SUNDAY AFTERNOON BEFORE SWEEPING EASTWARD DUE TO INCREASING WESTERLY COLUMN FLOW. HIGH TEMPERATURES TOMORROW WILL BE CONSIDERABLY COLD...SOME 10-13 DEGREES BELOW NORMAL. A RATHER RAW DAY WITH JUST ENOUGH WIND MAGNITUDE TO ALLOW FOR WIND CHILL VALUES IN THE SINGLE DIGITS BEFORE NOON...TOPPING OUT BETWEEN 10-15 DEGREES FOR THE AFTERNOON. TYPICAL QUESTION MARK EXISTS CONCERNING POTENTIAL FOR STRATOCUMULUS TOMORROW. THE AREAS POSITION/PROXIMITY WITHIN EDGE OF RETREATING TROUGH AND OVERALL ARCTIC AIRMASS SUGGESTS SUNSHINE WILL GREET US IN THE MORNING. THIS CERTAINLY HAS SUPPORT WHEN LOOKING AT SATELLITE IMAGERY OVER NORTHERN MINNESOTA. THE MODELED INVERSION AT ROUGHLY 5 KFT AGL IS INTERESTING AS THE SOLUTION SHOWS NO MOISTURE TRAPPED WITHIN THE STABLE STRATIFIED LAYER IMMEDIATELY ABOVE INVERSION BASE OR EVEN AT THE INVERSION BASE ITSELF. WILL CONTINUE WITH THE INHERITED FORECAST WHICH CALLS FOR SUNSHINE TOMORROW. MODELS ARE COMING INTO AN AGREEMENT WITH THE SYSTEM THAT WILL APPROACH THE AREA MONDAY NIGHT. OVERALL...SYSTEM DYNAMICAL SUPPORT APPEARS ABOVE AVERAGE AS THE SOUTHERN EXTENSION OF THE MIDLEVEL TROUGH WILL BECOME LINKED TO SOUTHERN STREAM JET STREAM ENERGY OVER THE FOUR CORNERS AREA SUNDAY NIGHT. THE TROUGH AXIS WHICH WILL BEGIN AT A POSITIVE TILT WILL TURN NEUTRAL MONDAY NIGHT AND EVENTUALLY NEGATIVE BY TUESDAY MORNING. THE PRECEDING WARM AIR ADVECTION...WING OF ISENTROPIC LIFT IS SHOWN TO BE DRY. IT WILL REQUIRE ACTUAL MOISTURE TRANSPORT AND UPPER LEVEL JET SUPPORT TO GET PRECIPITATION GOING. DELAYED PRECIPITATION ONSET TIMING A FEW HOURS...NOW EXPECTED MAINLY FOR THE FIRST HALF OF MONDAY NIGHT. THE GFS SOLUTION AND RESULTANT PRECIPITATION TYPE SEEMS HIGHLY SUSPECT GIVEN THE OVERALL HEIGHT PATTERN AND FORECASTED WIND FIELD. REST OF THE MEDIUM RANGE SUITE SUGGESTS THAT A SUBSTANTIAL WARM LAYER FROM SFC-5 KFT AGL WILL SLIDE IN SUPPORTING A RAPID TRANSITION TO RAIN. FROM THIS VANTAGE POINT THIS SYSTEM HAS THE POTENTIAL TO BECOME A HIGHER IMPACT WIND EVENT. RIGHT NOW...FORECASTED VALUES OF UPWARDS OF 30 KNOTS SEEMS GOOD...WITH ALL THE MAIN FEATURE SLIGHTLY OUT OF PHASE. SUBSEQUENT SHIFTS CAN FINE TUNE THIS. && .MARINE... OTHER THAN AN ACTIVE SNOW SHOWER PATTERN TONIGHT...MARINE CONDITIONS WILL BE FAVORABLE THROUGH SUNDAY IN TERMS OF WIND OVER ALL MARINE AREAS AND WAVES OVER THE OPEN WATERS OF LAKE HURON. AFTER THAT...A STRONG LOW PRESSURE SYSTEM IS EXPECTED TO DEVELOP OVER THE PLAINS AND MIDWEST AND MOVE THROUGH THE GREAT LAKES MONDAY AND TUESDAY. MILD AIR SPREADING NORTHWARD AHEAD OF THE SYSTEM WILL BRING RAIN TO ALL AREAS EXCEPT THE FAR NORTH REACHES OF LAKE HURON. A STRONG COLD FRONT IS EXPECTED TO BRING A SHARP WESTERLY WIND SHIFT TUESDAY MORNING BUT SPEEDS ARE EXPECTED TO REMAIN BELOW GALE FORCE FOR NOW. STRONG NORTHWEST WIND TRAILING THE FRONT WILL EASE IN SPEED DURING WEDNESDAY. && .AVIATION...ISSUED 1226 PM EST SAT FEB 16 2013 //DISCUSSION... CEILINGS LOOK TO BE PREDOMINATELY MVFR AS A WEAK SURFACE LOW AND ASSOCIATED COLD FRONT SINK SOUTH THROUGH THE AREA THIS AFTERNOON AND EVENING. THERE WILL BE A CONTINUED THREAT FOR SNOW SHOWERS...WITH CONVECTIVE NATURE TO THE ACTIVITY LEAD TO BRIEF IFR BURSTS...LEADING TO 1 TO 3 INCHES OF ACCUMULATIONS BY THE TIME THE SNOW ENDS LATE THIS EVENING. SKIES LOOK TO BE CLEARING OUT OVERNIGHT AS SURFACE HIGH SETTLES OVER WESTERN LOWER MICHIGAN...MAINTAIN GENERALLY LIGHT WINDS. WINDS TODAY WILL ALSO BE VERY LIGHT AND VARIABLE WITH THE SURFACE LOW TRACKING THROUGH. //DTW THRESHOLD THREATS... * HIGH CONFIDENCE IN CEILING HEIGHTS BELOW 5000 FEET THROUGH THIS EVENING. * HIGH CONFIDENCE IN PRECIPITATION TYPE BEING SNOW. * MEDIUM CONFIDENCE IN CIGS/VSBYS ABOVE 200 FT AND 1/2SM THIS AFTERNOON. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY...MIZ049-MIZ054-MIZ062...UNTIL 10 PM SATURDAY. WINTER WEATHER ADVISORY...MIZ055-MIZ063...UNTIL 2 AM SUNDAY. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...KURIMSKI LONG TERM....CB MARINE.......KURIMSKI AVIATION.....KURIMSKI YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
132 PM EST SAT FEB 16 2013 .SYNOPSIS... ISSUED AT 330 AM EST SAT FEB 16 2013 OCCASIONAL SNOW SHOWERS WILL CONTINUE TODAY AND INTO THIS EVENING. THE SNOW WILL BE HEAVY AT TIMES. LAKE SHORE AREAS WILL PICK UP ANOTHER 2 TO 4 INCHES...WHILE INLAND AREAS SEE 1 TO 2 INCHES. THE SNOW IS EXPECTED TO DIMINISH AFTER MIDNIGHT. BY MONDAY LOW PRESSURE WILL MOVE INTO THE UPPER MIDWEST. THIS SYSTEM WILL BRIEFLY BRING TEMPERATURES UP TO AROUND 40 BY MONDAY AFTERNOON. A PERIOD OF RAIN IS EXPECTED MONDAY AFTERNOON...THAT WILL TURN TO SNOW MONDAY NIGHT AND CONTINUE ON TUESDAY. MORE SNOW LOOKS LIKELY BY THURSDAY NIGHT AND FRIDAY. && .UPDATE... ISSUED AT 132 PM EST SAT FEB 16 2013 AS DISCUSSED IN THE RECENT WSW UPDATE...EXPECT MASON AND OCEANA TO SEE A MARKED DROP IN SNOW INTENSITY LATER THIS AFTERNOON BASED ON RAP MODEL GUIDANCE. FOR NOW THOUGH...RADAR RETURNS AT SIGNIFICANT RANGE BEYOND LUDINGTON COMBINED WITH IMPRESSIVE BANDS NOTED ON IR SATELLITE INDICATE INTENSE SNOWFALL IS STILL LIKELY ONGOING. HAVE DROPPED LAKE...NEWAYGO...AND KENT COUNTIES FROM THE ADVISORY. ACCUMULATIONS WERE LIMITED IN THESE AREAS. THE REMAINING THREE INLAND COUNTIES (BARRY...KALAMAZOO... AND CALHOUN) ARE KEPT IN AN ADVISORY TO ACCOUNT MOSTLY FOR RAPID VISIBILITY CHANGES. BIV RECENTLY DROPPED TO 1/4 MILE UNDER ONE OF THE STRONGER BANDS. ACCUMULATING SNOW SHOULD NOT BE SO MUCH OF AN ISSUE AWAY FROM THE LAKESHORE THE REST OF TODAY. PRECIPITATION GENERALLY APPEARS MORE CELLULAR ON RADAR. THIS COMBINED WITH MID-FEBRUARY DAYTIME INSOLATION IS KEEPING ACCUMULATIONS IN CHECK. UPDATE ISSUED AT 900 AM EST SAT FEB 16 2013 AFTER FURTHER CONSIDERATION...WILL BE UPGRADING MASON AND OCEANA TO A WARNING. RAP GUIDANCE SUGGESTS THAT AFTER A LULL THIS MORNING... ANOTHER SIGNIFICANT BAND MAY EXTEND FROM THESE COUNTIES THROUGH MUSKEGON...ALLEGAN...AND KALAMAZOO COUNTIES. UPDATE ISSUED AT 848 AM EST SAT FEB 16 2013 HAVE RECEIVED RECENT 8-12" SNOW REPORTS FROM SEVERAL LOCATIONS IN MASON AND OCEANA COUNTIES BENEATH AN AREA OF SATELLITE IR TEMPERATURES THAT WERE COLDER THAN -30C BETWEEN 11-12Z. 830 AM AWOS OBSERVATION AT HART INDICATES VISIBILITY BELOW 1/4 MILE. SUSPECT STRONG FRONTOGENETIC FORCING HAS BEEN AT PLAY AS TEMPERATURES AT RQB AND CAD HAD DROPPED AS MUCH AS 10 DEGREES OR MORE OVER THE PAST FEW HOURS. PRESENT THINKING IS THAT FGEN FORCING SHOULD DECREASE ALONG WITH MOST INTENSE SNOW THROUGH 10 AM. THIS IS SUPPORTED BY THE 16/09Z RUN OF THE HRRR...WHICH TAPERS PRECIP AND MOVES IT INLAND THROUGH 15Z. BELIEVING WE ARE ON A DOWNWARD TREND AFTER A PEAK IN SNOWFALL INTENSITY...WILL KEEP THE ADVISORY GOING IN THIS AREA AND UPDATE WITH THE LATEST THINKING. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 330 AM EST SAT FEB 16 2013 A RATHER DISORGANIZED PATTERN SO FAR EARLY THIS MORNING. A SURFACE TROUGH HAS BEEN CROSSING THE LAKE EARLY THIS MORNING AND THE WIND PATTERN AROUND THIS TROUGH HAS BEEN DISRUPTING ANY ORGANIZED LAKE EFFECT BANDS. THERE HAS BEEN A PERSISTENT BAND ACROSS THE NW COUNTIES NEAR LUDINGTON AND WHITEHALL...BUT OTHER SNOW BANDS HAVE BEEN FAIRLY TRANSITORY...KEEPING ACCUMS DOWN. THE SURFACE TROUGH LINGERS OVER THE AREA MUCH OF TODAY...SO FEEL WE MAY STRUGGLE TO GET PERSISTENT LES BANDS. RAP13 LOW LEVEL CONVERGENCE FIELDS SUGGEST THE LDM BAND MAY HOLD PAT MUCH OF THE DAY. IF THIS HOLDS TRUE...THIS BAND COULD PUT DOWN ANOTHER FOUR INCHES OR SO. A BETTER FLAIR UP IS INDICATED TOWARD 16Z FOR THE SW COUNTIES AND THIS IS PAINTED TO LAST THROUGH MUCH OF THE AFTERNOON. ALSO OF INTEREST IS A SYNOPTIC CONVERGENCE BAND THAT FLAIRS UP NORTH OF THE SURFACE TROUGH ALONG HIGHWAY 10 BY MID TO LATE AFTERNOON TODAY. IF THIS HOLDS TRUE THERE COULD BE A BURST OF SNOW ACROSS ALL OF THE NORTHERN COUNTIES INTO THIS EVENING. NEEDLESS TO SAY A RATHER COMPLEX PATTERN FOR TODAY. THOUGHT ABOUT DROPPING SOME OF THE COUNTIES IN THE ADVISORY AS THE LAKE EFFECT DOES NOT LOOK AS ROBUST ANYMORE. HOWEVER SINCE SNOW WILL STILL OCCUR...IT IS SORT OF HARD TO DROP HEADLINES IN THE MIDDLE OF AN EVENT. SO WILL LEAVE THE ADVISORY AS IS...ALTHOUGH WILL HIGHLIGHT SLIGHTLY LESS ACCUMS. ON THE OTHER HAND...INLAND AREAS COULD SEE A BIT MORE SNOW THEN WHAT IS CURRENTLY IN THE FORECAST DUE TO THE SYNOPTIC FEATURES. SO HAVE BUMPED UP ACCUMS A BIT INLAND... ESPECIAL NEAR HIGHWAY 10 TO COVER THE POSSIBLE CONVERGENCE BURST LATE TODAY INTO THIS EVENING. THE SNOW SHOULD BE DWINDLING AFTER MIDNIGHT AS THE SYSTEM PULLS AWAY AND INVERSION LEVELS COME DOWN. WILL CONTINUE WITH THE CHANCE POPS ON SUNDAY ALONG THE LAKE SHORE. WINDS WILL PIVOT FROM THE NNW EARLY IN THE DAY TO SW TOWARD MID DAY. THIS SHOULD PUSH ANY LAKE BAND INLAND...PRODUCING A BRIEF SNOW SHOWER MAINLY WEST OF U.S. 131. THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE MONDAY SYSTEM... BRINGING IT IN QUICKER. HAVE INCREASED POPS TO LIKELY BY MID TO LATE AFTERNOON. SHOULD BE WARM ENOUGH OF MOSTLY RAIN...ALTHOUGH A MIX SHOULD FALL OVER CENTRAL LOWER. .LONG TERM...(MONDAY NIGHT THROUGH FRIDAY) ISSUED AT 330 AM EST SAT FEB 16 2013 ACTIVE WEATHER PATTERN NEXT WEEK WITH TWO STORMS TO WATCH. A CLIPPER MOVES MOVES EAST MONDAY NIGHT WITH RAIN AND SNOW MIX CHANGING TO SNOW...FOLLOWED BY WEST FLOW LAKE EFFECT SNOW FROM TUESDAY AFTERNOON INTO WEDNESDAY. SFC AND SHORTWAVE UPPER RIDGING MOVES IN TO END THE LAKE EFFECT ON WEDNESDAY NIGHT...BUT THE LULL WILL BE SHORT LIVED AS A STORM TAKES SHAPE ACROSS THE PLAINS AND MOVES NORTHEAST SPREADING A BAND OF SNOW INTO LOWER MICHIGAN BY LATE THURSDAY. SNOW COULD BE HEAVY THURSDAY NIGHT AS AN AREA OF STRONG UPPER LEVEL DIVERGENCE AND DEEP LIFT MOVES OVER LOWER MICHIGAN. SNOW WILL CONTINUE ON FRIDAY AS AN UPPER LOW MOVES ACROSS ALTHOUGH WITH LESS INTENSITY AS DEEPER LIFT AND MOISTURE MOVES EAST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1256 PM EST SAT FEB 16 2013 COMPLICATED SCENARIO FOR AVIATION INTERESTS THIS AFTERNOON AND EVENING. LAKE EFFECT SNOW SHOWERS ARE ONGOING THIS AFTERNOON... HOWEVER THERE A FEW WEAK WAVES MOVING THROUGH THAT ARE COMPLICATING THE SITUATION AND ARE DISRUPTING TYPICAL BANDING. KGRR AND KLAN SEEM TO BE NORTH AND EAST OF THE MORE SIGNIFICANT SNOW SHOWERS...AND SHOULD REMAIN SO WITH ONLY SCATTERED SNOW SHOWERS THIS AFTERNOON. THE OTHER SITES ARE SEEING DECENT LAKE EFFECT AT TIMES. KMKG IS SEEING MORE LAKE EFFECT BANDING...WHILE KAZO...KBTL...AND KJXN SHOULD SEE THE EFFECTS OF THE WAVE THAT IS JUST WEST OF HASTINGS AT 18Z. SOME LOWER IFR-LIFR CONDITIONS ARE EXPECTED WITH THIS WAVE AT THOSE SITES...ESPECIALLY KBTL AND KJXN. WE EXPECT SNOW SHOWERS TO GRADUALLY SHIFT OFFSHORE THIS EVENING FROM NE TO SW AS A LAND BREEZE DEVELOPS AND THE FLOW GENERALLY SHIFTS TO THE NE FOR A PERIOD OF TIME. THIS SHOULD ALLOW MOST AREA TO CLEAR OUT. LATE TONIGHT...SNOW SHOWERS WILL COME BACK ONSHORE NORTH OF KMKG AFTER 09Z...AND THESE WILL GRADUALLY SPREAD INLAND SUN MORNING AND WEAKEN. && .MARINE... ISSUED AT 330 AM EST SAT FEB 16 2013 WILL KEEP MARINE HEADLINE AS IS...SCA THROUGH TONIGHT. && .HYDROLOGY... ISSUED AT 330 AM EST SAT FEB 16 2013 COLDER AIR HAS LOCKED UP ANY FURTHER SNOW MELT. WE WILL SEE A BRIEF WARM UP ON MONDAY WITH TEMPS REACHING AROUND 40 ALONG WITH SOME RAIN. SINCE THE WARM UP WILL BE BRIEF AND THE RAIN SHOULD BY LESS THAN A QUARTER INCH...NO HYDRO ISSUES ARE EXPECTED. HOWEVER A FLOOD ADVISORY REMAINS IN EFFECT FOR HIGH WATERS ON THE PERE MARQUETTE NEAR SCOTTVILLE. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST THIS EVENING FOR MIZ050-056-064-071-072. LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ065- 073. LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THIS EVENING FOR MIZ037- 043. LM...SMALL CRAFT ADVISORY UNTIL 4 AM EST SUNDAY FOR LMZ844>849. && $$ UPDATE...TJT SYNOPSIS...JK SHORT TERM...JK LONG TERM...OSTUNO AVIATION...NJJ HYDROLOGY...JK MARINE...JK
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1256 PM EST SAT FEB 16 2013 .SYNOPSIS... ISSUED AT 330 AM EST SAT FEB 16 2013 OCCASIONAL SNOW SHOWERS WILL CONTINUE TODAY AND INTO THIS EVENING. THE SNOW WILL BE HEAVY AT TIMES. LAKE SHORE AREAS WILL PICK UP ANOTHER 2 TO 4 INCHES...WHILE INLAND AREAS SEE 1 TO 2 INCHES. THE SNOW IS EXPECTED TO DIMINISH AFTER MIDNIGHT. BY MONDAY LOW PRESSURE WILL MOVE INTO THE UPPER MIDWEST. THIS SYSTEM WILL BRIEFLY BRING TEMPERATURES UP TO AROUND 40 BY MONDAY AFTERNOON. A PERIOD OF RAIN IS EXPECTED MONDAY AFTERNOON...THAT WILL TURN TO SNOW MONDAY NIGHT AND CONTINUE ON TUESDAY. MORE SNOW LOOKS LIKELY BY THURSDAY NIGHT AND FRIDAY. && .UPDATE... ISSUED AT 900 AM EST SAT FEB 16 2013 AFTER FURTHER CONSIDERATION...WILL BE UPGRADING MASON AND OCEANA TO A WARNING. RAP GUIDANCE SUGGESTS THAT AFTER A LULL THIS MORNING... ANOTHER SIGNIFICANT BAND MAY EXTEND FROM THESE COUNTIES THROUGH MUSKEGON...ALLEGAN...AND KALAMAZOO COUNTIES. UPDATE ISSUED AT 848 AM EST SAT FEB 16 2013 HAVE RECEIVED RECENT 8-12" SNOW REPORTS FROM SEVERAL LOCATIONS IN MASON AND OCEANA COUNTIES BENEATH AN AREA OF SATELLITE IR TEMPERATURES THAT WERE COLDER THAN -30C BETWEEN 11-12Z. 830 AM AWOS OBSERVATION AT HART INDICATES VISIBILITY BELOW 1/4 MILE. SUSPECT STRONG FRONTOGENETIC FORCING HAS BEEN AT PLAY AS TEMPERATURES AT RQB AND CAD HAD DROPPED AS MUCH AS 10 DEGREES OR MORE OVER THE PAST FEW HOURS. PRESENT THINKING IS THAT FGEN FORCING SHOULD DECREASE ALONG WITH MOST INTENSE SNOW THROUGH 10 AM. THIS IS SUPPORTED BY THE 16/09Z RUN OF THE HRRR...WHICH TAPERS PRECIP AND MOVES IT INLAND THROUGH 15Z. BELIEVING WE ARE ON A DOWNWARD TREND AFTER A PEAK IN SNOWFALL INTENSITY...WILL KEEP THE ADVISORY GOING IN THIS AREA AND UPDATE WITH THE LATEST THINKING. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 330 AM EST SAT FEB 16 2013 A RATHER DISORGANIZED PATTERN SO FAR EARLY THIS MORNING. A SURFACE TROUGH HAS BEEN CROSSING THE LAKE EARLY THIS MORNING AND THE WIND PATTERN AROUND THIS TROUGH HAS BEEN DISRUPTING ANY ORGANIZED LAKE EFFECT BANDS. THERE HAS BEEN A PERSISTENT BAND ACROSS THE NW COUNTIES NEAR LUDINGTON AND WHITEHALL...BUT OTHER SNOW BANDS HAVE BEEN FAIRLY TRANSITORY...KEEPING ACCUMS DOWN. THE SURFACE TROUGH LINGERS OVER THE AREA MUCH OF TODAY...SO FEEL WE MAY STRUGGLE TO GET PERSISTENT LES BANDS. RAP13 LOW LEVEL CONVERGENCE FIELDS SUGGEST THE LDM BAND MAY HOLD PAT MUCH OF THE DAY. IF THIS HOLDS TRUE...THIS BAND COULD PUT DOWN ANOTHER FOUR INCHES OR SO. A BETTER FLAIR UP IS INDICATED TOWARD 16Z FOR THE SW COUNTIES AND THIS IS PAINTED TO LAST THROUGH MUCH OF THE AFTERNOON. ALSO OF INTEREST IS A SYNOPTIC CONVERGENCE BAND THAT FLAIRS UP NORTH OF THE SURFACE TROUGH ALONG HIGHWAY 10 BY MID TO LATE AFTERNOON TODAY. IF THIS HOLDS TRUE THERE COULD BE A BURST OF SNOW ACROSS ALL OF THE NORTHERN COUNTIES INTO THIS EVENING. NEEDLESS TO SAY A RATHER COMPLEX PATTERN FOR TODAY. THOUGHT ABOUT DROPPING SOME OF THE COUNTIES IN THE ADVISORY AS THE LAKE EFFECT DOES NOT LOOK AS ROBUST ANYMORE. HOWEVER SINCE SNOW WILL STILL OCCUR...IT IS SORT OF HARD TO DROP HEADLINES IN THE MIDDLE OF AN EVENT. SO WILL LEAVE THE ADVISORY AS IS...ALTHOUGH WILL HIGHLIGHT SLIGHTLY LESS ACCUMS. ON THE OTHER HAND...INLAND AREAS COULD SEE A BIT MORE SNOW THEN WHAT IS CURRENTLY IN THE FORECAST DUE TO THE SYNOPTIC FEATURES. SO HAVE BUMPED UP ACCUMS A BIT INLAND... ESPECIAL NEAR HIGHWAY 10 TO COVER THE POSSIBLE CONVERGENCE BURST LATE TODAY INTO THIS EVENING. THE SNOW SHOULD BE DWINDLING AFTER MIDNIGHT AS THE SYSTEM PULLS AWAY AND INVERSION LEVELS COME DOWN. WILL CONTINUE WITH THE CHANCE POPS ON SUNDAY ALONG THE LAKE SHORE. WINDS WILL PIVOT FROM THE NNW EARLY IN THE DAY TO SW TOWARD MID DAY. THIS SHOULD PUSH ANY LAKE BAND INLAND...PRODUCING A BRIEF SNOW SHOWER MAINLY WEST OF U.S. 131. THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE MONDAY SYSTEM... BRINGING IT IN QUICKER. HAVE INCREASED POPS TO LIKELY BY MID TO LATE AFTERNOON. SHOULD BE WARM ENOUGH OF MOSTLY RAIN...ALTHOUGH A MIX SHOULD FALL OVER CENTRAL LOWER. .LONG TERM...(MONDAY NIGHT THROUGH FRIDAY) ISSUED AT 330 AM EST SAT FEB 16 2013 ACTIVE WEATHER PATTERN NEXT WEEK WITH TWO STORMS TO WATCH. A CLIPPER MOVES MOVES EAST MONDAY NIGHT WITH RAIN AND SNOW MIX CHANGING TO SNOW...FOLLOWED BY WEST FLOW LAKE EFFECT SNOW FROM TUESDAY AFTERNOON INTO WEDNESDAY. SFC AND SHORTWAVE UPPER RIDGING MOVES IN TO END THE LAKE EFFECT ON WEDNESDAY NIGHT...BUT THE LULL WILL BE SHORT LIVED AS A STORM TAKES SHAPE ACROSS THE PLAINS AND MOVES NORTHEAST SPREADING A BAND OF SNOW INTO LOWER MICHIGAN BY LATE THURSDAY. SNOW COULD BE HEAVY THURSDAY NIGHT AS AN AREA OF STRONG UPPER LEVEL DIVERGENCE AND DEEP LIFT MOVES OVER LOWER MICHIGAN. SNOW WILL CONTINUE ON FRIDAY AS AN UPPER LOW MOVES ACROSS ALTHOUGH WITH LESS INTENSITY AS DEEPER LIFT AND MOISTURE MOVES EAST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1256 PM EST SAT FEB 16 2013 COMPLICATED SCENARIO FOR AVIATION INTERESTS THIS AFTERNOON AND EVENING. LAKE EFFECT SNOW SHOWERS ARE ONGOING THIS AFTERNOON... HOWEVER THERE A FEW WEAK WAVES MOVING THROUGH THAT ARE COMPLICATING THE SITUATION AND ARE DISRUPTING TYPICAL BANDING. KGRR AND KLAN SEEM TO BE NORTH AND EAST OF THE MORE SIGNIFICANT SNOW SHOWERS...AND SHOULD REMAIN SO WITH ONLY SCATTERED SNOW SHOWERS THIS AFTERNOON. THE OTHER SITES ARE SEEING DECENT LAKE EFFECT AT TIMES. KMKG IS SEEING MORE LAKE EFFECT BANDING...WHILE KAZO...KBTL...AND KJXN SHOULD SEE THE EFFECTS OF THE WAVE THAT IS JUST WEST OF HASTINGS AT 18Z. SOME LOWER IFR-LIFR CONDITIONS ARE EXPECTED WITH THIS WAVE AT THOSE SITES...ESPECIALLY KBTL AND KJXN. WE EXPECT SNOW SHOWERS TO GRADUALLY SHIFT OFFSHORE THIS EVENING FROM NE TO SW AS A LAND BREEZE DEVELOPS AND THE FLOW GENERALLY SHIFTS TO THE NE FOR A PERIOD OF TIME. THIS SHOULD ALLOW MOST AREA TO CLEAR OUT. LATE TONIGHT...SNOW SHOWERS WILL COME BACK ONSHORE NORTH OF KMKG AFTER 09Z...AND THESE WILL GRADUALLY SPREAD INLAND SUN MORNING AND WEAKEN. && .MARINE... ISSUED AT 330 AM EST SAT FEB 16 2013 WILL KEEP MARINE HEADLINE AS IS...SCA THROUGH TONIGHT. && .HYDROLOGY... ISSUED AT 330 AM EST SAT FEB 16 2013 COLDER AIR HAS LOCKED UP ANY FURTHER SNOW MELT. WE WILL SEE A BRIEF WARM UP ON MONDAY WITH TEMPS REACHING AROUND 40 ALONG WITH SOME RAIN. SINCE THE WARM UP WILL BE BRIEF AND THE RAIN SHOULD BY LESS THAN A QUARTER INCH...NO HYDRO ISSUES ARE EXPECTED. HOWEVER A FLOOD ADVISORY REMAINS IN EFFECT FOR HIGH WATERS ON THE PERE MARQUETTE NEAR SCOTTVILLE. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST THIS EVENING FOR MIZ050-056-064-071-072. LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ065- 073. LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THIS EVENING FOR MIZ037- 043. LM...SMALL CRAFT ADVISORY UNTIL 4 AM EST SUNDAY FOR LMZ844>849. && $$ UPDATE...TJT SYNOPSIS...JK SHORT TERM...JK LONG TERM...OSTUNO AVIATION...NJJ HYDROLOGY...JK MARINE...JK
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1159 AM CST SAT FEB 16 2013 .UPDATE... ISSUED AT 1159 AM CST SAT FEB 16 2013 RADAR ACTIVITY IS NOW CONFINED TO AREAS EAST OF A KANW TO KBBW LINE...WITH THE WARM FRONT CURRENTLY FROM NEAR KBIR TO KANW TO KBBW. OBSERVATIONS ARE SHOWING VERY LIGHT SNOW OR FLURRIES FROM THIS ACTIVITY AND AS THE FRONT CONTINUES TO MOVE EAST THIS AFTERNOON...DO EXPECT ANY ACCUMULATING SNOW TO END IN THE NEXT FEW HOURS WITH ONLY FLURRIES THROUGH THE REMAINDER OF THE AFTERNOON. TEMPERATURES HAVE BEEN CLIMBING STEADILY THROUGH THE MORNING WITH READINGS IN THE MID TO UPPER 40S ACROSS MUCH OF THE AREA BY 18Z. THE EXCEPTION IS AREAS WHERE SNOW COVER REMAINS OVER THE WESTERN AND NORTHERN SANDHILLS...WITH LOWER TEMPERATURES IN THOSE AREAS. ALSO...BREEZY WINDS WILL OCCUR THROUGH THE AFTERNOON AS THE BOUNDARY LAYER MIXES DOWN SOME OF THE STRONGER WINDS ALOFT. MAY MIX A BIT HIGHER THAN 850MB THIS AFTERNOON...AND WITH WINDS AT THAT LEVEL OF 25KTS TO 35KTS...WOULD EXPECT A FEW HOURS OF SOME PRETTY BREEZY CONDITIONS THIS AFTERNOON. .UPDATE... MULTI MODEL BLEND OF RUC...HRRR...GEMREG...SREF...NAM...ECM PRODUCED WARMER TEMPS TODAY AND SUNDAY AS WARRANTED BY THE KUNR SOUNDING. NO DISCERNIBLE CHANGE OCCURRED TO THE ONGOING WEATHER USING THE SAME BLEND. A NEW FCST IS OUT...KIML COULD REACH 60F ON SUNDAY. OVERALL THE SNOW MOVES OUT QUICKLY THIS MORNING WITH CLEARING TO FOLLOW JUST A RAPIDLY ALONG AND WEST OF HIGHWAY 83. CLOUDS STAY IN LONGER EAST OF 83 AS ANOTHER BATCH OF CLOUDS MOVES DOWN FROM THE DAKOTAS LATER THIS MORNING. .PREV DISCUSSION... /ISSUED 413 AM CST SAT FEB 16 2013/ .UPDATE... RAN A BLEND OF ECM...GEMREG...NAM...RUC AND HRRR FOR THE ONGOING LIGHT SNOW ASSOCIATED WITH THE WARM FRONT ACROSS WRN NEB. THIS STILL GIVES LESS THAN AN INCH ACCUMULATION BUT THE RADAR IS LOOKING PRETTY ROBUST SO WE WILL HAVE TO WAIT FOR THE SNOW TO PASS OVER AN OBSERVATION SITE. THE LATEST DETAILS ON THE WEDS-THUR STORM ARE OUT IN THE FORM OF A SPECIAL WEATHER STATEMENT. PREV DISCUSSION... /ISSUED 337 AM CST SAT FEB 16 2013/ SHORT TERM...THROUGH 00Z MONDAY. THE GEMREG...NAM...RUC AND HRRR SHOW A DEVELOPING WARM FRONT MOVING EAST THROUGH NRN NEB THIS MORNING AND WEAKENING DURING THE AFTN. RADAR SUPPORTS THE DEVELOPMENT OF SCATTERED SNOW SHOWERS. SKIES SHOULD CLEAR OUT BEHIND THE WARM FRONT THROUGHOUT THE MORNING...AFTN AND EVENING HOURS. TEMPERATURES TODAY RANGE FROM NEAR 40 NORTHEAST TO MID 50S SOUTHWEST. LOW THROUGHOUT THE FCST AREA TONIGHT FALL TO AROUND 20. LONG TERM...00Z MONDAY AND BEYOND. MAIN FOCUS IN THE EXTENDED PERIOD REMAINS CENTERED ON THE POTENTIALLY SIGNIFICANT WINTER STORM POISED TO ARRIVE LATE WEDNESDAY LASTING INTO FRIDAY. CONFIDENCE IS INCREASING WITH THIS STORM AS THERE REMAINS STRONG SYNOPTIC AGREEMENT THROUGH THE EXTENDED PERIOD. MONDAY...BRIEF SHORTWAVE RIDGING ALOFT WILL BREAK DOWN AND BUILD EAST OF THE FORECAST AREA AS A SHORTWAVE TROUGH ADVANCED FROM THE ROCKIES ACROSS THE PLAINS. LONGER RANGE SOLUTIONS CONTINUE TO SHOW LIMITED SUPPORT FOR PRECIPITATION PRODUCTION...THUS WILL CONTINUE THE DRY FORECAST FOR NOW. THE WAVE WILL PULL A COLD FRONT ACROSS THE CWA LATE SUNDAY INTO EARLY MONDAY...WITH STRONG CAA AND A TIGHT GRADIENT TO FOLLOW...MONDAY WILL BE BLUSTERY WITH HIGHS RUNNING 15F OR MORE COOLER THAN SUNDAY AFTERNOON. INTO TUESDAY...THE OVERALL SYNOPTIC PATTERN REMAINS FAIRLY PROGRESSIVE AS SHORTWAVE RIDGING BUILDS ACROSS WESTERN NEBRASKA...HOWEVER TEMPERATURES WILL BE SLOW TO WARM TUESDAY AND WEDNESDAY HOWEVER AS EASTERLY FLOW WILL RECYCLE ARCTIC AIR BACK ACROSS MUCH OF THE CWA. SEEING A LARGE RANGE IN HIGHS FOR BOTH MONDAY AND TUESDAY...WITH 20S ACROSS NORTH CENTRAL NEBRASKA...AND POSSIBLY UPPER 30S TO LOW 40S ACROSS THE FAR SOUTHWEST. ATTENTION NOW TURNS TO THE POTENTIALLY BIG WINTER STORM FOR WEDNESDAY NIGHT AND THURSDAY. LONG RANGE SOLUTIONS CONTINUE TO ADVERTISE A STRONG UPPER LOW WHICH WILL EJECT FROM THE FOUR CORNERS REGION WEDNESDAY NIGHT INTO THE CENTRAL PLAINS BY EARLY THURSDAY. CYCLOGENESIS WILL BE ONGOING ACROSS THE EASTERN PLAINS OF COLORADO ON WEDNESDAY...WITH A RAPID DEEPENING OF THE SURFACE LOW EXPECTED. GIVEN STRONG SURFACE HIGH PRESSURE OF ~1040MB OVER THE GREAT LAKES REGION...AN INCREASING PRESSURE GRADIENT WILL DEVELOP ACROSS THE CWA...WITH THE POTENTIAL OF 25-30 MPH WIND GUSTS WEDNESDAY AND THURSDAY. THE MODELS ALSO SUGGEST PLENTIFUL MOISTURE ADVECTION IN ADVANCE OF THE SYSTEM...WITH EASTERLY UPSLOPE POSSIBLY ALLOWING FOR SNOW PRODUCTION AS EARLY AS LATE WEDNESDAY NIGHT. MEANWHILE...DOWNSTREAM OF THE UPPER TROUGH...RIDGING AND PV DESTRUCTION ACROSS THE UPPER MISSISSIPPI RIVER VALLEY WILL ALLOW THE TROUGH/CLOSED LOW TO BECOME NEGATIVELY TILTED...WITH THE PROGRESSION OF THE H5 LOW SLOWED. MODEL CONSENSUS INDICATES THE TRACK OF THE H5 LOW FROM SE COLORADO INTO NEBRASKA FROM 06Z THURSDAY THROUGH 00Z FRIDAY...PLACING MUCH OF THE FORECAST AREA UNDER A BROAD DEFORMATION BAND FOR A 12-18 HOUR PERIOD....THUS THE POTENTIAL OF A LONG SNOW EVENT IS POSSIBLE. THERE ARE A FEW DIFFERENCES WITH THE TRACK OF THE H5 LOW...MAINLY THE GFS AND ENSEMBLES ARE MORE PROGRESSIVE WITH THE TRACK OF THE LOW...CARRYING IT INTO SOUTHEASTERN NEBRASKA BY 00Z FRIDAY. THE EC WOBBLES THE H5 LOW NORTHWARD THROUGH CENTRAL NEBRASKA INTO SOUTH DAKOTA BY 06Z FRIDAY. REGARDLESS OF THE DIFFERENCES...MEAN /GFS AND EC/ QPF ACCUMULATION ARE CLOSE TO EACH OTHER /~.75 OF INCH AT KLBF/...WITH THE ENSEMBLES RUNNING SLIGHTLY HIGHER /.85/...ALL OF THIS IS EXPECTED TO FALL AS SNOW...POSSIBLY WIND DRIVEN. GIVEN THE INGREDIENTS...A MAJOR WINTER STORM IS TAKING SHAPE. && $$ .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1159 AM CST SAT FEB 16 2013 LIGHT SNOW SHOWERS OR FLURRIES WILL BE CONFINED TO LOCATIONS EAST OF A LINE FROM KANW TO KBBW THIS AFTERNOON AND WILL DIMINISH BY EVENING AS A WARM FRONT PROGRESSES ACROSS THE AREA INTO EASTERN NEBRASKA. SKIES HAVE CLEARED OVER MUCH OF WESTERN NEBRASKA BY 18Z...HOWEVER WITH AFTERNOON MIXING...COULD SEE SOME SCATTERED CLOUDS NEAR 7K FEET. ALSO WITH THE MIXING OF THE BOUNDARY LAYER EXPECTED...SHOULD SEE NORTHWEST WINDS WITH GUSTS TO 25 OR 30KTS THROUGH THE AFTERNOON HOURS. CLEAR SKIES ARE EXPECTED OVERNIGHT...WITH WINDS DIMINISHING AS WELL. FOR SUNDAY...A COLD FRONT WILL MAKE ITS WAY INTO THE CENTRAL AND NORTHERN PLAINS. WINDS WILL SHIFT TO THE SOUTHWEST BY SUNDAY MORNING AHEAD OF THE FRONT AND INCREASE BY 18Z. THE FRONT IS NOT EXPECTED TO MOVE THROUGH KVTN OR KLBF UNTIL SUNDAY AFTERNOON OR EVENING SO A WIND SHIFT WILL NOT COME THROUGH THIS TIME PERIOD. MAY SEE AN INCREASE OF CLOUDS IN ADVANCE OF THE FRONT ON SUNDAY...BUT CEILINGS WILL BE VFR. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...BROOKS SHORT TERM...JACOBS LONG TERM...JACOBS AVIATION...BROOKS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
320 PM CST SAT FEB 16 2013 .SHORT TERM... TEMPS TONIGHT A CHALLENGE ONCE AGAIN. LOW CLOUDS/FOG FROM THIS MORNING CLEARED OFF AND A SOUTH-SOUTHEAST WIND HELPING TO WARM THINGS UP A BIT...BUT TEMPS QUITE VARIABLE WITH TEMPS STRUGGLING INTO THE MID TEENS IN MOST OF THE FCST AREA WHILE A FEW SPOTS IN THE MN TREES SEEING MID 20S. AREA OF CLOUD COVER DVL-JMS REGION REALLY BREAKING UP SOME THIS AFTN BUT IDEA IS THESE CLOUDS ASSOC WITH 850MB WARM ADV WILL SPREAD EAST TONIGHT. UPSTREAM CANADIAN RADAR AND OBS SHOWS SOME LIGHT SNOW BRANDON-DAUPHIN-PORTAGE MB REGION AND DID COORD WITH WFO BIS AND SPREAD SOME FLURRIES SOUTHEAST THIS EVENING INTO NE ND. FOR LATER TONIGHT...CLOUD BAND MOVES MORE INTO MN FCST AREA AND RAP ISENTROPIC FCSTS INDICATE SOME LIFT 750-850 MB REGION DEVELOPING IN BDE-BJI AREA BY 12Z SUN. THUS KEPT LOW POP FOR -SN IN LAKE OF THE WOODS REGION AND SPREAD MENTION OF FLURRIES A BIT MORE BACK INTO NRN VALLEY AND REST OF NW MN. BUFKIT SOUNDINGS SHOW PTYPE ALL -SN THRU 12Z. AS FOR TEMPS...QUITE CHALLENGING AS SHOULD SEE SOME DROP AGAIN IN THE EAST BUT OTHERWISE FAIRLY STEADY IF NOT RISE A BIT OVERNIGHT IN ERN ND. USED A BLEND OF MODEL GUIDANCE FOR HOURLY TEMPS. FOR SUNDAY...MAIN ISENTROPIC LIFT HANGS OVER LAKE OF THE WOODS REGION WITH MAJORITY OF THE FCST IN DRY SLOT AT 850 MB. SOUNDINGS DO SHOW SOME 925 MB MOISTURE BUT LIFT IN THAT LAYER APPEARS INSUFFICIENT TO PRODUCE ANY FZDZ WE HAD IN THE PREV FCST. THROUGH COORD WITH ABR/MPX/BIS REMOVED FZDZ MENTION SUNDAY. PTYPES IN FAR NW MN WHERE POPS ARE WOULD BE -SN. TEMPS SHOULD WARM ESP LATER ON IN THE DAY AS WINDS TURN A MORE WEST AND ALLOW TEMPS TO WARM INTO THE LOWER 30S. OTHERWISE EXPECT A STIFF SOUTH-SOUTHEAST WINDS LATE TONIGHT THRU SUNDAY MIDDAY. 12Z GFS MODEL A BIT MORE LIKE THE OTHER MODELS NOW IN REGARDS TO SUN NIGHT-MON SYSTEM. 00Z/06Z SAT RUNS A BIT AGGRESSIVE. SFC LOW WILL MOVE FROM EC SASK INTO SW MB SUNDAY AFTN THEN TOWARD LAKE OF THE WOODS REGION 06Z MON. MAIN SNOW WITH THIS LOW AND KEPT IDEA OF 2-4 INCHES IN RRT/BDE AREAS. OTHERWISE MAIN ACTION WILL WAIT WITH COLD FRONT WHICH WILL DROP DOWN SUN LATE NIGHT INTO MONDAY MORNING. SHOULD SEE SOME LIGHT SNOW WITH THIS...MORE SNOW SHOWERY...ALONG WITH A PD OF STRONG WINDS MONDAY. BUFKIT SOUNDINGS SHOW ADIABATIC TO AROUND 880 MB AT GFK/FAR MONDAY MIDDAY WHERE WINDS OF 30-35 KTS SHOULD MIX DOWN. STRONG COLD ADV AS WELL AS HIGH BUILDS IN AND SFC LOW STRENGTHENS TO OUR EAST. ISSUED A SPECIAL WX STATEMENT FOR MONDAY AS WIND AND LIGHT SNOW WILL CAUSE BLOWING SNOW AND LIKELY NASTY TRAVEL CONDITIONS. TEMPS TO DROP WELL BLOW ZERO MONDAY NIGHT AND RECOVER ONLY SLIGHTLY TO THE SINGLE DIGITS ABOVE AND BLO ZERO TUESDAY WITH DIMINISHING WINDS. WIND CHILLS THOUGH EARLY TUESDAY MAY DROP TO -30 TO -35F IN NE ND. .LONG TERM (TUE NIGHT-SAT)... MID LEVEL RIDGING AND SFC HIGH PRESSURE SHOULD BE OVER THE FA TO START THE LONG TERM PERIOD. WITH THE SFC HIGH AND A COLD AIRMASS IN PLACE TEMPS WILL STILL BE CHILLY TUE NIGHT INTO WED. FLOW WILL TRANSITION BACK TO THE SOUTHWEST WITH ANOTHER COLORADO LOW SYSTEM EJECTING OUT ON THU. HPC MEAN TAKES THIS LOW FROM SE COLORADO AT 12Z THU TO NEAR CHICAGO BY 12Z FRI WHICH USES A GLOBAL MEAN. LATEST RAW 12Z MODEL GUIDANCE FROM BOTH THE ECMWF AND GFS IS FURTHER WEST WITH THE SFC LOW. THEREFORE THERE IS STILL UNCERTAINTY WITH THE TRACK OF THIS NEXT SYSTEM YET. AS FOR NOW WILL LEAVE HIGHER THAN GUIDANCE PCPN CHANCES ACROSS THE SOUTHEAST FA FOR THU INTO THU NIGHT AND SEE WHAT LATER RUNS HAVE IN STORE. MAY BE LINGERING LIGHT SNOW FROM THIS SYSTEM ALL THE WAY INTO SAT. && .AVIATION... CLOUD COVER REMAINS THE MAIN AVIATION CHALLENGE. HAD THOUGHT SOME OF THE CLOUDS TO THE WEST OR NORTH WOULD WORK INTO THE VALLEY DURING THE AFTERNOON BUT THEY HAVE BEEN THINNING INSTEAD. EITHER WAY THE HEIGHT RANGES WOULD BE IN THE VFR RANGE. SHOULD SEE STEADY SOUTH WINDS TONIGHT BECOME GUSTY BY SUNDAY MORNING. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ RIDDLE/GODON
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
348 PM EST SAT FEB 16 2013 .SYNOPSIS... IN THE WAKE OF A DEPARTING UPPER LEVEL TROUGH...HIGH PRESSURE WILL BUILD OVER THE AREA ON SUNDAY. RETURN FLOW AND SOUTHERLY WINDS WILL BRING WARMER AIR TO THE REGION MONDAY AND OVERNIGHT AHEAD OF THE NEXT COLD FRONT THAT WILL CROSS LATE MONDAY NIGHT. RAIN WILL OVERSPREAD THE REGION AHEAD OF THIS NEXT FRONTAL PASSAGE. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... UPPER LEVEL TROUGH IS MOVING EAST THROUGH THE NORTHERN OHIO VALLEY/GREAT LAKES REGION TONIGHT. THE BEST COLD PUSH IS ONGOING RIGHT NOW AND HELPING TO CONTINUE THE CONVECTION GOING ON THIS AFTERNOON. WITH THE LOSS OF DAYTIME INSOLATION THE SURFACE WILL COOL OFF TONIGHT AND THERMAL DIFFERENTIAL CAUSING THE SNOW SHOWERS WILL QUICKLY DISSIPATE THIS EARLY EVENING...EVEN AS THE COLDEST AIR CONTINUES TO SETTLE OVER THE REGION LATE TONIGHT. NAM AND HRRR WERE PREVIOUSLY SHOWING A WEAK AREA OF FORCING AND LIGHT SNOW RUNNING FROM ABOUT INDIANAPOLIS AT 0Z TONIGHT TOWARDS CINCINNATI AROUND 6Z AND THEN SOUTH OF A MAYSVILLE/VANCEBURG LINE BY DAYBREAK. I INCLUDED SOME LIGHT SNOW IN THESE AREAS BUT THE ACTUAL OCCURRENCE OF THIS EVENT REMAINS TO BE SEEN AND MAY NOT MATERIALIZE. SKY COVER IS QUITE CELLULAR LOOKING IN NATURE AND SHOULD DISSIPATE RELATIVELY QUICKLY OUTSIDE OF CENTRAL OHIO TONIGHT...AND IN THE INDY-CINCY-NORTHERN KY LINE PREVIOUSLY MENTIONED FOR INCREASED SNOW POTENTIAL. THIS RELATIVE CLEARING WILL LET TEMPERATURES DROP INTO THE TEENS WITH SOME SINGLE DIGITS POSSIBLY IN COLDER LOW- LYING AREAS. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... A BRIEF RESPITE BETWEEN SYSTEMS WILL BE FOUND SUNDAY AND WARMER AIR WILL REALLY BEGIN TO BE USHERED IN MONDAY AFTER A MINOR DROP OR RELATIVELY STEADY TEMPERATURES IN THE LOWER 20S SUNDAY NIGHT. MILD AIR ON MONDAY AND OVERNIGHT WILL BE SHORT LIVED. RAIN WILL SPREAD EAST IN THE EVENING AS THE DAYTIME SHOULD JUST SEE INCREASING CLOUD COVER FROM WEST TO EAST. THE RAIN WILL BE EVERYWHERE BY MIDNIGHT AND IS EXPECTED TO TAIL OFF QUICKLY WITH THE PASSAGE OF THE FRONT...BEFORE DAYBREAK IN INDIANA. WINDS WILL SHIFT WEST BEHIND THE FRONT AND DRIER AIR BEING USHERED IN WILL MARK THE END OF THE RAIN. TEMPERATURES IN THE WARM SECTOR MONDAY SHOULD RISE INTO THE UPPER 40S AND LOW 50S...WITH SOME MID 50S POSSIBLE IN KENTUCKY. && .LONG TERM /TUESDAY THROUGH SATURDAY/... PERIOD BEGINS WITH A CDFNT FORECASTED TO BE PUSHING ACROSS THE FA. EXACT PLACEMENT OF THE FRONT AT 12Z TUESDAY WILL AFFECT THE PCPN TYPE AND POPS FOR THE FIRST FEW HOURS OF THE DAY. THE 12Z NAM APPEARS TO BE THE QUICKEST WITH THE FRONT...PUSHING IT INTO THE APPALACHIANS ALREADY. THE MORE GLOBAL MODELS HAVE THE FRONT SLOWER...MAYBE AROUND I-75. TRENDED TOWARDS THE CONSENSUS...THUS KEPT LIKELY POPS IN THE E AHEAD OF THE FNT...BUT DRIED OUT THE POPS POST FRONTAL. WITH FROPA SO EARLY...WILL PROBABLY SEE FALLING OR STEADY TEMPERATURES FOR TUESDAY. ALSO THREW IN A MENTION OF A CHC OF SNOW SHOWERS FOR LATE TUE MORNING INTO TUE AFTN AS THE MODELS ARE SHOWING CYCLONIC SFC FLOW COMBINING WITH WLY CAA AT H8. HIGH PRESSURE BUILDS DOWN INTO THE LOWER OHIO VALLEY TUE NIGHT INTO WED BEFORE LIFTING NE ACROSS THE FA WED NGT. THIS SHOULD PROVIDE DRY CONDITIONS FOR THE PERIOD...WITH NRN SECTIONS SEEING MORE CLOUDS THAN THE S TUE NGT AND WED...BEFORE MOSTLY CLEAR SKIES PREVAIL WED NGT. SYSTEM DIGS INTO THE SRN ROCKIES WED NGT...THEN EJECTS OUT THU INTO THU NGT. MODELS ARE SHOWING THEIR TYPICAL SPREAD. THE CMC IS THE QUICKEST THIS RUN IN BRINGING RETURN PCPN TO THE FA THU AFTN. THE 12Z RUNS OF THE GFS AND ECMWF ARE SLOWER...LIMITING POPS TO THE SW. THICKNESSES WILL BE COLD ENUF FOR SOME RAIN/SNOW AT THE ONSET. AS THE CENTER OF THE SYSTEM LIFTS OUT THRU THE PLAINS...AN AREA OF PCPN WILL BE PUSHED ACROSS THE FA THU NGT INTO FRI. PCPN WILL EITHER BE SN OR RA/SN MIX UNTIL A WRMFNT GRADUALLY BRINGS IN WARMER AIR CHANGING THE PCPN TO RA BEFORE IT ENDS ON FRIDAY. HIGH PRESSURE THEN BUILDS IN FOR FRIDAY. COLD AIR WILL WORK IN TUESDAY NIGHT DROPPING TEMPERATURES IN THE TEENS AND LOWER 20S. THE COOL NLY FLOW ON WED WILL KEEP TEMPS DOWN IN THE UPPER 20S N TO THE MID 30S NRN KY. THE CLEAR SKIES WILL ALLOW TEMPERATURES TO DROP BACK INTO THE TEENS AND LOWER 20S AGAIN. ONLY EXPECT HIGHS ON THU TO MAKE THE 30S AHEAD OF THE STORM SYSTEM...BUT WITH RISING TEMPS THU NGT. HIGHS FRIDAY SHOULD MAKE THE 40S AS THE REGION GETS WARM SECTORED. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... WIDESPREAD FLURRIES AND OCCASIONAL BRIEF HEAVY SNOW SHOWERS WILL CONTINUE TO AFFECT THE CMH/LCK/ILN/DAY TERMINALS THROUGH ABOUT 21Z BEFORE SHIFTING EAST OF THE AREA. EXPECT MAINLY VFR/MVFR CONDITIONS IN THIS TIME...BUT IN THE HEAVIEST OF SNOW SHOWERS COULD SEE IFR OR EVEN LIFR VSBYS FOR A BRIEF PERIOD OF TIME AND CIGS AROUND 1500FT. SECONDARY SUBTLE WAVE UPSTREAM OVER WI/IL/IA EXPECTED TO POSSIBLY BRING A MUCH SMALLER/MORE LIMITED SWATH OF SNOW TO CVG-AREA TERMINALS AFTER SUNSET...WITH LOW CONFIDENCE ON TIMING. WENT WITH A MIDDLE OF THE ROAD 04Z-07Z TIMEFRAME WHICH IS A LITTLE LATER THAN RAP AND A LITTLE EARLIER THAN NAM-WRF...BUT DON/T EXPECT OVERALL IMPACTS FROM THIS TO BE LARGE...THINKING MVFR CONDITIONS AT WORST. CLOUDS OVERNIGHT AND ESP INTO SUNDAY MORNING ARE PROBLEMATIC...WAS NOT EAGER TO IMPROVE MVFR/VFR BKN CIGS OVERNIGHT DESPITE PASSAGE OF UPPER TROUGH AND DEEPER SUBSIDENCE. THERE IS SOME LOW CLOUD UPSTREAM CAUGHT UNDERNEATH THE WEAK SURFACE FLOW /RIDGE AXIS/ WHERE THE LOW LEVEL FLOW TURNS FROM NWLY TO SWLY BUT SOME OF THIS IS ALSO OPEN- CELLULAR IN NATURE. IN GENERAL DELAYED THE CLEARING FROM BKN-SCT A FEW HOURS FROM INHERITED TAFS...THOUGH A PERIOD OF CLEARING IS POSSIBLE NEAR CVG LATE THIS AFTN/EVE BEFORE NEXT BATCH OF MOISTURE ARRIVES. OUTLOOK...MVFR CIGS AND VSBYS POSSIBLE MONDAY NIGHT AND EARLY TUESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...FRANKS NEAR TERM...FRANKS SHORT TERM...FRANKS LONG TERM...SITES AVIATION...BINAU
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
143 PM EST SAT FEB 16 2013 .SYNOPSIS... AN UPPER LEVEL TROUGH MOVING ACROSS THE GREAT LAKES WILL RESULT IN SEASONABLY COOL TEMPERATURES AND A CHANCE OF SNOW SHOWERS TODAY. HIGH PRESSURE WILL BUILD INTO THE AREA ON SUNDAY BEFORE A LOW PRESSURE SYSTEM MOVES IN FROM THE WEST MONDAY NIGHT. INCREASING SOUTHERLY FLOW AHEAD OF THE LOW WILL RESULT IN MUCH WARMER TEMPERATURES BY MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 16.12Z KILN RAOB SAMPLED THE IMPORTANT ASPECTS OF THE COLD/SHARP TROUGH THAT IS SHIFTING THROUGH THE AREA TODAY. WITH 500MB HEIGHTS/TEMPS NEAR 5250M/-40C RESPECTIVELY...THIS IS AN IMPRESSIVELY DEEP SYSTEM THAT WILL LEAD TO YET ANOTHER DAY OF HIGHLY VARIABLE/CHANGEABLE WEATHER INCLUDING SNOW SHOWERS WITH LOW VSBYS. THE STEEP LOW LEVEL LAPSE RATE ENVIRONMENT IS ALREADY IN PLACE PER THE 12Z SOUNDING /850MB TEMPS TO -14C/ AND THESE SHOULD FALL FURTHER TOWARD -17C INTO THIS EVENING...AND WITH THE TROUGH AXIS STILL TO THE WEST...TROPOSPHERIC COOLING /DECREASING STABILITY/ WILL CONTINUE TO SUPPORT AN INCREASE IN CLOUDS AND EVENTUALLY SNOW SHOWER DEVELOPMENT. THERE GENERALLY IS STRONG AGREEMENT FROM THE CONVECTION-ALLOWING SUITE OF GUIDANCE INCLUDING HRRR/SPC-WRF/NSSL-WRF THAT AREA OF SNOW SHOWERS NOW DEVELOPING TO OUR NORTHWEST/WEST WILL INCREASE IN COVERAGE/INTENSITY AS IT MOVES THROUGH OUR AREA LATE THIS MORNING/AFTN...WITH HIGHEST COVERAGE NORTH OF I-70...AND LEAST COVERAGE OVER NRN KY AND SERN IN. HAVE INCREASED SNOW CHANCES MOST AREAS FROM 16Z-21Z AND INDICATED ACCUMS UP TO AN INCH IN THE NORTH...THOUGH ACTUAL ACCUMS WILL BE HIGHLY DEPENDENT ON THE VERY SMALL SCALE CONVECTIVE SNOW BURSTS. RAP/NAM FCST BUFR SOUNDINGS /C25...KCMH...AND KILN/ ALL SUGGEST THAT DESPITE THE SHALLOW NATURE OF MOISTURE/CONVECTIVE SNOW SHOWERS...THAT SUPERSATURATION WITH RESPECT TO ICE IS LIKELY TO EXIST IN THE MOST INTENSE SQUALLS IN -12C TO -18C REGION OF SOUNDING WHICH WOULD LEAD TO LARGE DENDRITIC FLAKES AND HEAVY RATES /LOW VSBYS/ EVEN IN SHORT DURATION. ACCUMULATIONS WON/T BE THE IMPACT THOUGH...IT WILL BE RAPID REDUCTIONS IN VSBYS TO BELOW 1/2SM IN THE HEAVIEST SQUALLS...AND WITH A VERY COLD START THIS MORNING ROAD TEMPS MAY NOT BE AS RECEPTIVE TO MELTING...ESPECIALLY WITH WINDS COMING UP A BIT OUT OF THE NW THIS AFTERNOON AND TEMPS REMAINING IN THE 20S. SO THE AMBIENT SETUP SEEMS TO SUPPORT A HIGHER THAN NORMAL THREAT OF RAPIDLY CHANGING ROAD CONDITIONS AND VISIBILITIES THAT MAY LEAD TO MORE SIGNIFICANT IMPACTS ON OUR INTERSTATE HIGHWAY SYSTEM WITHIN THESE INTENSE SNOW BURSTS. WILL BE AGGRESSIVE WITH SPECIAL WEATHER STATEMENTS AND HWO WORDING AS THE SNOW SHOWERS DEVELOP LATER THIS MORNING/AFTN. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... THE UPPER LEVEL TROUGH AXIS WILL BEGIN TO SHIFT EAST OF THE AREA BY TONIGHT WITH MID/UPPER LEVEL RIDGING SLIDING OVERHEAD SUNDAY NIGHT INTO MONDAY. THIS WILL ALLOW FOR DRYING CONDITIONS AND DECREASING CLOUDS BY SUNDAY. HOWEVER...WE DO NOT REALLY GET INTO RETURN FLOW UNTIL SUNDAY NIGHT SO EXPECT SUNDAY TO REMAIN ON THE COOLER SIDE WITH HIGHS ONLY IN THE UPPER 20S TO LOWER 30S. WE COULD HAVE SOME EARLY LOWS SUNDAY EVENING WITH TEMPERATURES THEN STEADYING OFF OR EVEN RISING A LITTLE LATE AS LOW LEVEL SOUTHERLY FLOW BEGINS TO PICK UP AND WE GET SOME INCREASING CLOUDS. INCREASING SOUTHWESTERLY LOW LEVEL FLOW THROUGH THE DAY ON MONDAY WILL LEAD TO GOOD WAA AND SOME BREEZY CONDITIONS. THIS SHOULD PUSH TEMPERATURES WELL ABOVE NORMAL WITH HIGHS ON MONDAY INTO THE UPPER 40S TO LOWER/MID 50S. STRENGTHENING ISENTROPIC LIFT THROUGH THE DAY WILL LIKELY ALLOW FOR SOME SHOWERS TO DEVELOP THROUGH MID TO LATE AFTERNOON...ESPECIALLY ACROSS THE WEST. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... A COLD FRONT WILL BEGIN TO WORK INTO THE AREA OVERNIGHT MONDAY NIGHT AND MOVE EAST OF THE REGION TUESDAY MORNING. THIS FEATURE WILL ALLOW FOR COLDER AIR TO WORK INTO THE FA AND RAIN WILL BEGIN TO MIX AND THEN CHANGE OVER TO SNOW OVERNIGHT MONDAY NIGHT INTO TUESDAY. DUE TO THE FRONTAL PASSAGE TEMPERATURES WILL STRUGGLE TO RISE ON TUESDAY AND WILL ACTUALLY FALL SLOWLY THROUGH MOST OF THE DAY. SNOW WILL COME TO AN END TUESDAY AFTERNOON AND HIGH PRESSURE WILL WORK INTO THE FA. WITH MOSTLY CLEAR TO PARTLY CLOUDY SKIES TUESDAY NIGHT AND WEDNESDAY NIGHT TEMPERATURES WILL DROP DOWN INTO THE TEENS TO THE 20S FOR LOWS. THE NEXT STORM SYSTEM WILL BEGIN TO BRING PRECIPITATION INTO THE FA THURSDAY AFTERNOON WITH MORE WIDESPREAD PRECIPITATION ACROSS THE FA THURSDAY NIGHT. PRECIPITATION WILL BEGIN TO TAPER OFF ACROSS THE FA ON FRIDAY. PRECIPITATION WILL BE A MIX OF RAIN AND SNOW WITH THIS SYSTEM. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... WIDESPREAD FLURRIES AND OCCASIONAL BRIEF HEAVY SNOW SHOWERS WILL CONTINUE TO AFFECT THE CMH/LCK/ILN/DAY TERMINALS THROUGH ABOUT 21Z BEFORE SHIFTING EAST OF THE AREA. EXPECT MAINLY VFR/MVFR CONDITIONS IN THIS TIME...BUT IN THE HEAVIEST OF SNOW SHOWERS COULD SEE IFR OR EVEN LIFR VSBYS FOR A BRIEF PERIOD OF TIME AND CIGS AROUND 1500FT. SECONDARY SUBTLE WAVE UPSTREAM OVER WI/IL/IA EXPECTED TO POSSIBLY BRING A MUCH SMALLER/MORE LIMITED SWATH OF SNOW TO CVG-AREA TERMINALS AFTER SUNSET...WITH LOW CONFIDENCE ON TIMING. WENT WITH A MIDDLE OF THE ROAD 04Z-07Z TIMEFRAME WHICH IS A LITTLE LATER THAN RAP AND A LITTLE EARLIER THAN NAM-WRF...BUT DON/T EXPECT OVERALL IMPACTS FROM THIS TO BE LARGE...THINKING MVFR CONDITIONS AT WORST. CLOUDS OVERNIGHT AND ESP INTO SUNDAY MORNING ARE PROBLEMATIC...WAS NOT EAGER TO IMPROVE MVFR/VFR BKN CIGS OVERNIGHT DESPITE PASSAGE OF UPPER TROUGH AND DEEPER SUBSIDENCE. THERE IS SOME LOW CLOUD UPSTREAM CAUGHT UNDERNEATH THE WEAK SURFACE FLOW /RIDGE AXIS/ WHERE THE LOW LEVEL FLOW TURNS FROM NWLY TO SWLY BUT SOME OF THIS IS ALSO OPEN- CELLULAR IN NATURE. IN GENERAL DELAYED THE CLEARING FROM BKN-SCT A FEW HOURS FROM INHERITED TAFS...THOUGH A PERIOD OF CLEARING IS POSSIBLE NEAR CVG LATE THIS AFTN/EVE BEFORE NEXT BATCH OF MOISTURE ARRIVES. OUTLOOK...MVFR CIGS AND VSBYS POSSIBLE MONDAY NIGHT AND EARLY TUESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...JGL NEAR TERM...BINAU SHORT TERM...JGL LONG TERM...NOVAK AVIATION...BINAU
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AREA FORECAST DISCUSSION
NWS LA CROSSE WI
327 PM CST SAT FEB 16 2013 .SHORT TERM...THROUGH TUESDAY NIGHT 326 PM CST SAT FEB 16 2013 MUCH OF THE TIME TODAY WAS SPENT WORKING ON MONDAY INTO TUESDAY. IMPACTS LOOK TO BE MINIMAL AS MAIN PRECIPITATION REGION LOOKS TO ADVECT IN JUST EAST OF THE FORECAST AREA. CLOUDS HAVE BEEN A TOUGH FORECAST AS OF LATE...AND TONIGHT THEY COULD HAVE A HUGE IMPACT ON LOW TEMPERATURES. CURRENT GOES SATELLITE IMAGERY SHOWING CLOUDS EXPANDING IN WRN MN WEST OF THE SURFACE RIDGE AXIS FROM KINL TO KALO. MAINLY CUMULUS FIELDS ARE AFFECTING THE FORECAST AREA WITH THOSE EXPECTED TO DISSIPATE BY LATE AFTERNOON. SURFACE OBSERVATIONS SHOWING A STATIONARY FRONT LOCATED FROM ABOUT KFSD-KDSM WITH WARM AIR TO THE SOUTHWEST AND CONVERGENT FLOW INTO NE IA. GOES WATER VAPOR SHOWING THE MONDAY S/WV WELL NOW COMING ONTO THE WEST COAST WITH THE NRN ENERGY OVER BRITISH COLUMBIA AND THE 16.19Z RAP INDICATING A TROPOPAUSE FOLD TO 400MB INTO THE OR COAST REPRESENTING THE SRN ENERGY THAT IS FORECAST TO DIG INTO THE CENTRAL U.S. KUIL WASHINGTON RAOB HAD A 150M/12HR HEIGHT FALL THIS MORNING AHEAD OF THIS POTENT SHORTWAVE TROUGH. HAVE LOWERED THE LOW TONIGHT ACROSS CENTRAL WI AS THE SURFACE RIDGE WILL BE RIGHT OVERHEAD MOST OF THE NIGHT AND CLOUDS ARE FORECAST TO REMAIN MINIMAL. HAVE DROPPED LOWS 5-7F THERE TONIGHT FROM PREVIOUS FORECAST. CLOUDS ARE TOUGH THOUGH AND AM THINKING TWO AREAS COULD DEVELOP STRATUS...CURRENT HEAVY CUMULUS AREA OVER NRN WI AND CONVERGENT BOUNDARY ACROSS IA. THE NRN WI AREA COULD EXPAND OVER NRN FORECAST AREA LATE AND CLOUDS WILL ALSO SPREAD IN FROM THE SW. THUS...LOW CONFIDENCE IN FORECAST CLOUDS AND LOWS TONIGHT...BUT FORECASTING THE CENTRAL FORECAST AREA TO REMAIN MOSTLY CLEAR. WARM ADVECTION TO KICK IN SUNDAY AND PEAK SUNDAY NIGHT WITH WARMING OCCURRING INTO MONDAY WEATHER SYSTEM. 16.12Z MODEL CONSENSUS IS TO STILL DEVELOP THE NRN CYCLONE THE MOST...NORTH OF THE GREAT LAKES...WITH THE SRN ENERGY CAUSING WEAK CYCLOGENESIS ALONG THE FRONTAL BOUNDARY AS IT PASSES TO THE SE OF THE FORECAST AREA. SOME SPREAD STILL REMAINS IN THE GUIDANCE. THE 16.12Z NAM REMAINS CONSISTENT WITH IT/S PREVIOUS RUNS OF THE DRY OUTLIER. THE 16.12Z CANADIAN GLOBAL GEM STILL INSISTS ON A WET 0.30 INCHES AREA-WIDE WITH THIS SYSTEM /AND HIGHS IN THE 40S/. STILL PREFER THE CONSISTENT ECMWF/GFS RUNS ON THE OUTCOME FOR THIS SYSTEM. IT APPEARS THE MAIN MOISTURE AXIS WILL ONLY GRAZE THE ERN FORECAST AREA FROM CENTRAL WI TO SWRN WI...A STEP EAST FROM PREVIOUS MODEL RUNS. THIS SAME AREA WILL SEE THE DEEPEST SURFACE-BASED SATURATION COME IN MONDAY MORNING /KOVS 0-2 KM/...WITH THE LAYER MORE SHALLOW FURTHER TO THE NW /KEAU 1KM/. NW OF THE SURFACE WAVE...WOULD THINK A BIT OF ENHANCEMENT IN THE DEFORMATION WILL OCCUR AND HAVE KEPT HIGHEST PRECIPITATION CHANCES IN THAT SWRN-CENTRAL WI AREA...TAPERING LOWER TO THE NORTHWEST. IT APPEARS DEEP SATURATION TO COLDER THAN -10C TO GET ICE GROWTH WILL BE TROUBLESOME/SPOTTY OR JUST PLAIN HARD TO FORECAST WITH THIS SYSTEM. THE Q-G FORCING IS MODERATE ALOFT AND WEAKER IN THE LOW LEVELS PROVIDING OVERALL A WEAK BUT PRESENT LIFT SIGNAL. BUT REVIEWING MODEL SOUNDINGS FROM THE 16.09Z SREF AND 16.12Z NAM/GFS THERE IS CONSISTENT STRUGGLES WITH SATURATION NOTED...AND THUS HAVE GONE WITH A MAJORITY OF LIQUID IN THE FORECAST UNTIL THE COLD FRONT MOVES IN LATER MONDAY WITH VERY STRONG COLD ADVECTION TO DRIVE THE ICE PROCESS AND SNOW CONVERSION. THIS SATURATION STRUGGLE AWAY FROM THE SURFACE WAVE IS ALSO WHY PRECIPITATION CHANCES ARENT HIGHER FOR THIS FORECAST. MONDAY MORNING WILL SEE THE MOISTURE INCREASE AND SURFACE TEMPERATURES WARMING TO NEAR OR ABOVE FREEZING IN THE AFTERNOON. THIS WILL CAUSE A FZDZ POSSIBILITY MAINLY IN THE MORNING IF THE LAYER CAN PRECIPITATE...PROBABLY VERY LIGHT AMOUNTS AROUND 0.01-0.02 INCHES TO PROVIDE A LIGHT GLAZE AFTER COMMUTE TIME. MANY AREAS SOUTH OF I-90 WILL WARM TO ABOVE FREEZING BY MID-DAY...ESPECIALLY CLOSE TO THE MOIST AXIS SO IMPACTS WOULD BE MINIMAL THERE...OR AT LEAST SHORT LIVED. HAVE KEPT FZDZ STILL POSSIBLE FOR POINTS WITH AIR TEMPERATURES OF 35F OR COLDER AS ROADS MAY STILL BE SLOWER TO RECOVER TO ABOVE FREEZING. THE NORTHERN AND WESTERN AREAS COULD SEE FZDZ PERIODICALLY MONDAY THROUGH THE DAY...POSSIBLE MIXING WITH SNOW AS SATURATION OCCURS IN A PATCHY WAY. THE COLD FRONT WILL SWEEP IN WITH VERY STRONG COLD ADVECTION CONVERTING ALL LIGHT LIQUID PRECIPITATION TO SNOW. WITH THE COLD ADVECTION STRONG...LAPSE RATES IN THE LOWEST 1 KM ARE QUITE STEEP AND WILL PROMOTE WIND GUSTS IN THE 25 TO 35 MPH RANGE LATE MONDAY AND OVERNIGHT. HAVE INCREASED THE WINDS WITH THIS FORECAST BASED ON 16.12Z NAM/GFS BLEND. OVERALL...COMFORT REMAINS LOW ON THIS SYSTEM /I HAVE MORE CONFIDENCE IN THE THU-FRI SNOW/ BUT MY FEELING IS THAT THE IMPACTS WILL BE MINOR. DO NOT FEEL A NEED FOR A HEADLINE ON THIS SYSTEM AS THE LIQUID AMOUNTS LOOK TO BE PRETTY LIGHT. IN THE DEFORMATION AREA TEMPERATURES WOULD BE WARMEST AND MAINLY RAIN WOULD FALL. BUT THERE ARE SOME HINTS THAT UP TO A TENTH OF PRECIPITATION COULD FALL MONDAY AWAY FROM THE MOISTURE AXIS /KEAU SREF MEAN GIVES 0.07 OF FZDZ/ SO IT IS STILL A SYSTEM TO WATCH. .LONG TERM...WEDNESDAY THROUGH SATURDAY 326 PM CST SAT FEB 16 2013 THE FOCUS REMAINS ON THE INCREASINGLY ADVERTISED LATE WEEK SYSTEM AND THE DEGREE OF IMPACT IT WILL HAVE ON THE UPPER MIDWEST. LEADING UP TO THAT FEATURE...WEDNESDAY LOOKS TO BE A TRANSITION DAY WITH MORNING COLD ADVECTION AS A SURFACE HIGH AND UPPER LEVEL RIDGE AXIS REMAINS TO THE WEST OF THE FORECAST AREA. A COLD DAY ON TAP AS MORNING LOWS IN THE SINGLE DIGITS BELOW/ABOVE ZERO LOOK TO RISE INTO ONLY THE TEENS. THE RIDGE IS THEN EXPECTED TO BUILD ACROSS BY WEDNESDAY NIGHT...LEADING TO RETURN SOUTHERLY FLOW. A WESTERN CONUS TROUGH THEN DIGS AND MOVES EAST...EJECTING THE MAIN SHORTWAVE TROUGH OUT OF THE COLORADO ROCKIES BY 12Z THURSDAY. SURFACE LOW DEEPENS RAPIDLY ACROSS THE CENTRAL PLAINS THURSDAY...LIFTING TOWARD THE AREA. THE 16.12Z GFS ENSEMBLE REMAINS CLOSELY PACKED WITH A LOW TRACK ALONG A KANSAS CITY TO NORTHERN ILLINOIS LINE THURSDAY NIGHT INTO FRIDAY AFTERNOON. THE 16.12Z ECMWF TOOK A STEP NORTHWEST WITH ITS SURFACE LOW TRACK AND THE 16.12Z GEM AND FIM REMAIN THE SOUTHERLY OUTLIERS. THE GFS SEEMS TO BE A GOOD COMPROMISE. EARLIER TIMING ISSUES APPEAR TO BE RESOLVED FOR NOW. YESTERDAY/S CONCERNS ABOUT THE FILLING UPPER LEVEL TROUGH / SURFACE LOW AND ITS IMPACT WERE MUTED SLIGHTLY SINCE THE 16.12Z GFS...ECMWF AND FIM CAME IN A BIT STRONGER. HOWEVER...500 MB HEIGHT STANDARDIZED ANOMALIES STILL RISE FROM -3.5 ACROSS THE CENTRAL PLAINS...TO AROUND -0.5 BY 12Z FRIDAY WHICH SUGGESTS A WEAKENING TREND AND THE SYSTEM NOT NEARLY AS WOUND UP AS IT MAY BE IN THE CENTRAL PLAINS. PRECIPITATION WOULD OVERSPREAD THE AREA DURING THE AFTERNOON THURSDAY...WITH THE MAIN WARM ADVECTIVE WING SWINGING THROUGH THURSDAY NIGHT AND OVERNIGHT FRIDAY. THIS WOULD BE WHEN THE HIGHEST SNOW RATES OCCUR. AS THE SURFACE LOW THEN MOVES NEARBY...WRAP AROUND / DEFORMATION BANDING SNOW WOULD LINGER THROUGHOUT FRIDAY. SOUNDINGS STILL POINT TO AN ALL SNOW EVENT WITH THE WARMEST AIR REMAINING SOUTH OF THE AREA. THE MODEL CONSISTENCY AND RUN-TO-RUN SIMILARITIES REMAIN VERY ABOVE AVERAGE AND REMARKABLE FOR IT STILL BEING 6 DAYS OUT. GIVEN THE FEATURE IS CURRENTLY OVER THE DATA SPARSE NORTHERN PACIFIC...THERE CERTAINLY WILL BE FINE-TUNE DETAILS TO ESTABLISH. PRECIPITATION AMOUNTS TOOK A STEP UP IN THE LATEST ROUND OF GUIDANCE THOUGH STILL REMAIN BETWEEN 0.7 TO 1.0 INCH. CONFIDENCE CONTINUES TO GROW IN A WARNING LEVEL EVENT WITH WIDESPREAD 6 TO 10 INCH AMOUNTS IF THE CURRENT AND PAST SOLUTIONS INDEED VERIFY. THE BIG PICTURE IS THAT THOSE WITH INTERESTS AND TRAVEL CONCERNS LATE NEXT WEEK SHOULD CONTINUE TO MONITOR AND FOR NOW...HAVE CONTINUED TO PUSH HIGHER PRECIPITATION CHANCES THURSDAY NIGHT...AND TRENDED FRIDAY HIGHER AS WELL SINCE IF THE SYSTEM DOES SLOW DOWN / FILL IN THEN THERE WOULD CERTAINLY BE LINGERING DEFORMATION BANDING SNOW ACROSS MUCH OF THE AREA. THE PROLONGED DURATION / THURSDAY NIGHT THROUGH LATE FRIDAY NIGHT / COULD PRESENT SOME CHALLENGES FOR TRAVELERS AND ROAD CREWS AS WELL. && .AVIATION...THROUGH 18Z SUNDAY 1128 AM CST SAT FEB 16 2013 THE MAIN CONCERNS ARE IN THE NEAR TERM WITH SKY CONDITIONS AND SOME LIGHT SNOW POSSIBLY GETTING INTO RST. THIS BAND OF LIGHT SNOW HAS BEEN JUST TO THE WEST OF RST ALL MORNING AND HAS BROUGHT VISIBILITY DOWN TO IFR...MAINLY AT 1-2SM. THE CLOUDS DO APPEAR TO BE DIMINISHING IN COVERAGE AND THAT SHOULD BE THE TREND THROUGH THE AFTERNOON HOURS. FURTHER EAST AT LSE..MAINLY LOOKING AT A LOW END VFR BKN CLOUD DECK AT 3500-4500FT THROUGH THE AFTERNOON BEFORE SUBSIDENCE KICKS IN AND HELPS CLEAR THE CLOUDS LATER THIS AFTERNOON ON INTO THE EVENING. WINDS WILL REMAIN LIGHT THROUGH THE NIGHT AS A RIDGE AXIS OF HIGH PRESSURE MOVES THROUGH BUT AFTER IT PASSES BY TOMORROW MORNING...THE PRESSURE GRADIENT WILL TIGHTEN UP WITH SOUTHEAST WINDS INCREASING TO 10-20KTS BY LATE MORNING. && .ARX WATCHES/WARNINGS/ADVISORIES... 151 PM CST SAT FEB 16 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BAUMGARDT LONG TERM...TAYLOR AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
234 PM CST SAT FEB 16 2013 .SYNOPSIS... ISSUED AT 223 PM CST SAT FEB 16 2013 MODERATING TEMPS WITH SOME LIGHT TO MODERATE PRECIPITATION MONDAY NIGHT AND TUESDAY. STILL PLENTY OF QUESTIONS ABOUT THE NEXT SYSTEM EXPECTED TO ARRIVE LATE IN THE WEEK. UPR FLOW ACRS NOAM WL START OUT WITH A BROAD RIDGE OVER THE ERN PAC/WRN NOAM...ALBEIT WITH STG SHRTWV RIGHT IN THE MIDDLE OF THE RIDGE POSN. A DEEP TROF WAS OVER ERN NOAM...WITH RIDGING OVER THE WRN ATL. THE SHRTWV NOW IN THE WRN RIDGE POSN AND ITS SUCCESSOR WL BOTH DIG PROGRESSIVELY FARTHER W...EVENTUALLY PULLING THE MEAN TROF POSN BACK INTO THE WESTERN CONUS BY MID-WK. MEANWHILE...THE DOWNSTREAM PATTERN OVER THE ATL WL BREAK DOWN INTO A COMPLEX BLOCKING REGIME. THE BLOCKING WL EVOLVE WWD WITH TIME... RESULTING IN A SPLIT FLOW ACRS MUCH OF THE CONUS BY NEXT WEEKEND. THE TWO MAJOR SHRTWVS WORKING ACRS THE CONUS DURING THE PERIOD WL BOTH SUPPORT STG CYCLONES. THE CHANGING UPR PATTERN AND PASSAGE OF THE CYCLONES WL TAKE TEMPS ON A ROLLERCOASTER RIDE DURING THE PERIOD. THEY/LL START OUT COLD...QUICKLY WARM EARLY IN THE WEEK... DROP BACK TO BLO NORMAL MID-WEEK...THEN SETTLE BACK CLOSER TO NORMAL AS THE FLOW SETTLES INTO SPLIT REGIME. GIVEN THE 2 SIG SYSTEMS LIKELY TO IMPACT THE AREA...PCPN AMNTS WL PROBABLY END UP AOA NORMAL. && .SHORT TERM...TONIGHT AND SUNDAY ISSUED AT 223 PM CST SAT FEB 16 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE RIDGE STRETCHING FROM TEXAS TO ONTARIO THIS AFTERNOON. STEEPENING LOW LEVEL LAPSE RATES AND FLOW OFF SUPERIOR CONTRIBUTED TO A WIDESPREAD DIURNAL CU FIELD...WHICH SPREAD SOUTH ACROSS MUCH OF THE CWA BY EARLY THIS AFTERNOON. LAKE EFFECT SNOW SHOWERS REMAINED CONFINED TO NORTHERN VILAS COUNTY AND POINTS NORTH AND VSBYS IN THIS AREA SUGGEST ONLY MINOR ACCUMS AT BEST. PRETTY QUIET UPSTREAM AS WELL. FGEN INDUCED BAND OF CLOUDS AND LIGHT SNOW OVER THE PLAINS IS SLIDING SE WHILE SKY CONDITIONS ARE CLEARING OVER MINNESOTA. CLOUD TRENDS AND TEMPS ARE THE MAIN FORECAST CONCERNS IN THE SHORT TERM. TONIGHT...SURFACE HIGH PRESSURE TO MOVE ACROSS THE REGION AND THIS SHOULD RESULT IN LOW LEVEL FLOW BECOMING LIGHT THIS EVENING. ANTICIPATING STRATO-CU TO RAPIDLY DIMINISH WITH LOSS OF DAYTIME HEATING EARLY THIS EVENING...EXCEPT OVER NORTH-CENTRAL WISCONSIN WHERE IT SHOULD TAKE A FEW HOURS LONGER. AS A RESULT...EXPECT SKY CONDITIONS TO BECOME CLEAR TO MOSTLY CLEAR ACROSS THE REGION BY LATE THIS EVENING. STRATUS UPSTREAM THIS MORNING BENEATH THE RIDGE AXIS SEEMED ALIGNED WITH A LOW LEVEL THERMAL GRADIENT. THIS GRADIENT DOES NOT MOVE MUCH TONIGHT...SO AM NOT EXPECTING CLOUDS TO REFORM BENEATH THE SURFACE HIGH. TEMPS LAST NIGHT FELL INTO THE TEENS BELOW ZERO OVER N-C WISCONSIN. SHOULD HAVE LIGHTER WINDS IN THE BOUNDARY LAYER AND THE PWAT MINIMUM OVERHEAD...SO HAVE DROPPED TEMPS FROM THE PREVIOUS FORECAST. SUNDAY...HIGH PRESSURE MOVES EAST OF THE REGION AND RETURN FLOW WILL PUSH A WARM FRONT INTO THE NORTHERN MISSISSIPPI VALLEY BY THE AFTERNOON. THOUGH MID AND HIGH CLOUDS WILL BE INCREASING THROUGH THE DAY...DEEPER MOISTURE WILL STAY WELL OFF TO THE NORTHWEST OVER NORTHERN MINNESOTA AND SOUTH-CENTRAL CANADA. HIGHS WILL BE CONSIDERABLY WARMER THAN TODAYS READINGS...AND MOSTLY RANGE FROM THE LOWER TO MIDDLE 20S. .LONG TERM...SUNDAY NIGHT THROUGH SATURDAY ISSUED AT 223 PM CST SAT FEB 16 2013 WAA ON THE BACK SIDE OF DEPARTING RIDGE WL KICK INTO HIGH GEAR SUN NGT. THE STRONGEST ISENT LIFT AND BEST CHC AT SATURATION WL BE ACRS THE N. WENT WITH CHC POPS THERE...AND KEPT THE S DRY. EXPECT EVENING MINS THEN RISING TEMPS. COMPLEX STORM SYSTEM DRIVEN BY PHASING SHRTWVS WL BE ORGANIZING AS IT CROSSES THE AREA MON...THEN DEEPEN JUST OFF TO OUR E MON NGT INTO TUE. RAISED POPS AS FORCING LOOKS FAIRLY STG. BUT MOISTURE WL BE LIMITED...ESP INITIALLY. THAT WL PROBABLY RESULT IN ANOTHER EVENT WITH MESSY MIX OF SN/DZ/FZDZ DEPENDING ON WHETHER SUFFICIENT MID-LVL MOISTURE IS PRESENT AT ANY TIME TO SEED THE LOWER CLDS FM ABV. MODEL FCST SOUNDINGS SUGGEST LOWER-LEVELS OVER E-C WI COULD BRIEFLY BE WARM ENOUGH FOR JUST RAIN MON AFTN EVEN IF MOISTURE IS DEEP AT THAT TIME. WENT WITH MAINLY SN/FZDZ ACRS THE NW AND RA/SN IN THE SE ON MON. E-C WI COULD CERTAINLY SEE DZ RATHER THAN RAIN... BUT WANTED TO AVOID HAVING TOO MANY PCPN TYPES IN THE FCST. PCPN SHOULD CHG TO SNOW MON NGT...WITH SHSN ON THE BACK SIDE OF THE SYSTEM CONTG INTO TUE. UPPED POPS AS UPR TROF WL BE SHARPENING RIGHT ACRS THE AREA DURING THAT TIME. THINKING RIGHT NOW IS THAT THIS WL BE A 1-3 INCH EVENT...WITH THE HIGHER TOTALS IN THE NE. LAKE-EFFECT OFF LAKE SUPERIOR COULD BOOST TOTALS EVEN FURTHER OVER THE SNOWBELT...THOUGH THAT DEPENDS ON EXACT TRAJECTORIES SO WON/T GET TOO SPECIFIC WITH THAT YET. A BREAK FM THE SIG PCPN THEN EXPECTED WED INTO THU AS UPR RIDGE SHARPENS ACRS THE AREA. STG...COLD...VERY DRY LOW-LEVEL ANTICYCLONE WL BE RIDGING SWD INTO THE RGN FM THE HUDSON BAY AREA. LOW-LEVEL WINDS WL VEER ARND TO THE E...AND ALTHOUGH THE UPSTREAM AIR WL BE VERY DRY AND INVERSION HEIGHTS WL BE LOW...WL PROBABLY GET SOME LAKE FLURRIES INTO E-C WI. STILL A LOT OF QUESTIONS ABOUT THE SYSTEM HEADING INTO THE AREA DURING THE LATTER PART OF THE WEEK. DON/T LIKE THAT THE SYSTEM WL BE DRIVING INTO A DOWNSTREAM BLOCK AND HAVE VERY DRY AIR FEEDING INTO IT FM THE E AT LOW-LEVELS. THAT/S A CLASSIC LATE WINTER/EARLY SPRING FCST PROBLEM HERE...AND IT TYPICALLY RESULTS IN A CONSTANT DELAYING OF THE ONSET OF PCPN...AND OFTEN A REDUCTION IN PCPN TOTALS. ON THE OTHER HAND...IF SYSTEM CAN GET PCPN INTO THE AREA...DOWNSTREAM BLOCKING WL CAUSE IT TO SLOW TO A CRAWL...AND RESULT IN A LONG-DURATION EVENT. FEELING RIGHT NOW IS THAT THIS IS A SYSTEM THAT WL HAVE IT/S GREATEST IMPACT OUT IN THE PLAINS. MAX SNOWS WL PROBABLY END UP IN THE SW PART OF THE FCST AREA...AND THEY WILL PROBABLY BE CONSIDERABLY LESS THAN WHAT FALLS TO OUR SW. AT THIS POINT...WAS CONTENT WITH INITIALIZATION GRIDS THAT NEVER WENT BEYOND LIKELY POPS. CERTAINLY PLENTY OF TIME FOR LATER SHIFTS TO ADJUST FCST. WL CONT TO MENTION SYSTEM IN THE HWO...BUT DON/T PLAN ON PLAYING THIS UP AS A BIG STORM. && .AVIATION...FOR 18Z TAF ISSUANCE ISSUED AT 1132 AM CST SAT FEB 16 2013 AS NORTH FLOW CONTINUES OFF LAKE SUPERIOR...CONDITIONS TO BECOME SCT TO BKN THIS AFTERNOON...HIGHER PROBABILITIES OVER NORTH- CENTRAL AND NORTHEAST WISCONSIN THAN FOR CENTRAL WISCONSIN. MVFR CIGS WILL LIKELY IMPACT RHI AND POSSIBLY AUW/CWA THIS AFTERNOON...BUT SNOW SHOWERS SHOULD REMAIN NORTH OF THE AIRPORTS...FROM VILAS COUNTY TOWARDS LAKE SUPERIOR. HIGH PRESSURE OVER THE AREA TONIGHT WILL HELP SKIES CLEAR AND WINDS BECOME LIGHT AND VARIABLE. MID AND HIGH CLOUDS WILL BE ON THE INCREASE ON SUNDAY AHEAD OF AN APPROACHING WARM FRONT...BUT ANY THREAT OF PRECIP TO HOLD OFF UNTIL SUNDAY NIGHT. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS.......SKOWRONSKI SHORT TERM.....MPC LONG TERM......SKOWRONSKI AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1128 AM CST SAT FEB 16 2013 .SHORT TERM...THIS MORNING AND AFTERNOON 1003 AM CST SAT FEB 16 2013 CURRENTLY TRACKING A BAND OF LIGHT SNOW MOVING ACROSS SOUTHEAST MINNESOTA AND NORTHEAST IOWA WHICH HAS DROPPED VISIBILITY DOWN TO LESS THAN A MILE AT TIMES. SOME OF THAT MAY BE DUE TO SOME FOG BEING REPORTED IN CENTRAL MINNESOTA...BUT MOST OF THE VISIBILITY REDUCTIONS SHOULD BE DUE TO THE SNOW FALLING. AUSTIN CITY POLICE REPORTED THAT THERE WERE LARGE SNOW FLAKES COMING DOWN AROUND 9AM AND THAT SOME MINOR ACCUMULATIONS WERE BEGINNING. THE FORCING TO PRODUCE THIS SNOW APPEARS TO BE FROM WARM AIR ADVECTION AROUND 925MB ACCORDING TO 16.14Z RAP BUFKIT SOUNDINGS. THESE SOUNDINGS ALSO SHOW THE SATURATED THERMAL PROFILE BEING IN THE PEAK DENDRITIC GROWTH ZONE FROM THE SURFACE UP THROUGH ITS SATURATED LAYER AT ABOUT 4KFT. THE 16.14Z RAP SHOWS THIS AREA OF HIGH LOW LEVEL RELATIVE HUMIDITY AND WARM AIR ADVECTION PROPAGATING TO THE SOUTHEAST THROUGH THE EARLY PART OF THE AFTERNOON BEFORE ENTERING NORTHERN ILLINOIS AFTER 21Z. SO THE PRECIPITATION SHOULD END THEN. BASED ON ALL THIS...UPDATED THE FORECAST TO GO FROM FLURRIES TO THE PERIODS OF SNOW SHOWER THROUGH A PORTION OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA THROUGH 21Z. ALSO ENDED THE FLURRIES AFTER 21Z REGION-WIDE...BUT THAT WILL HAVE TO BE RE-EVALUATED THIS AFTERNOON BASED ON THE CLOUD COVER AT THAT TIME. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY 240 AM CST SAT FEB 16 2013 THIS SYSTEM WILL THEN PULL AWAY FROM THE REGION MONDAY NIGHT AND TUESDAY WITH A LINGERING CHANCE FOR SOME LIGHT SNOW ACROSS THE ENTIRE AREA MONDAY NIGHT AND JUST IN THE I94 CORRIDOR TUESDAY. AS THIS SYSTEM APPROACHES THE EAST COAST OF CANADA...THE MODELS NOW SHOW IS SLOWS CONSIDERABLY WITH RIDGING BUILDING OVER THE CENTRAL PORTIONS OF THE COUNTRY. THE NEXT SYSTEM WILL COME ONSHORE AND INTO THE ROCKIES TO FORM AN OMEGA BLOCK TYPE PATTERN BY WEDNESDAY. HOWEVER...THE SYSTEM COMING IN FROM THE WEST IS EXPECTED TO CONTINUE AN ATTEMPT TO MOVE INTO THE RIDGE AS THERE WILL BE MORE SYSTEMS TOPPING THE PACIFIC RIDGE AND MOVING TOWARD THE ROCKIES. THE MODELS NOW SHOW THE FIRST SYSTEM COMING OUT OF THE WEST TO LIFT INTO THE NORTHERN PLAINS BY FRIDAY AS THE DOWNSTREAM BLOCK REMAINS IN PLACE AND BEGINS TO FILL IN. THIS IS A DRAMATIC SHIFT IN THE UPPER AIR PATTERN FROM PREVIOUS MODEL RUNS WHICH DID NOT SHOW AN OMEGA BLOCK DEVELOPING AND WERE PROGRESSIVE WITH THE SYSTEM. THE SURFACE LOW IS NOW HANDLED QUITE DIFFERENTLY BY THE MODELS WITH THEM SHOWING A VERY DEEP LOW COMING OUT OF THE SOUTHERN ROCKIES WEDNESDAY NIGHT. WITH A FILLING UPPER LEVEL LOW...ALL THE MODELS SHOW THE SURFACE SYSTEM TO BE FILLING AS WELL...BUT TO DIFFERENT DEGREES ON HOW FAST THIS WILL HAPPEN. WOULD HAVE PREFERRED TO LET THE MODEL CONSENSUS GRIDS RIDE UNTIL CONFIDENCE ON HOW THIS SYSTEM WILL EVOLVE BECOMES HIGHER. HOWEVER...UNABLE TO DO THIS AND HAD TO RAISE THE PRECIPITATION CHANCES THURSDAY AFTERNOON AND NIGHT TO REMAIN IN COLLABORATION WITH SURROUNDING OFFICES. ENDED UP WITH 60 PERCENT ACROSS THE SOUTHWEST THURSDAY AFTERNOON ON THE LEADING EDGE OF THE PRECIPITATION SHIELD AND THEN 70 PERCENT FOR MUCH OF THE AREA THURSDAY NIGHT. && .AVIATION...THROUGH 18Z SUNDAY 1128 AM CST SAT FEB 16 2013 THE MAIN CONCERNS ARE IN THE NEAR TERM WITH SKY CONDITIONS AND SOME LIGHT SNOW POSSIBLY GETTING INTO RST. THIS BAND OF LIGHT SNOW HAS BEEN JUST TO THE WEST OF RST ALL MORNING AND HAS BROUGHT VISIBILITY DOWN TO IFR...MAINLY AT 1-2SM. THE CLOUDS DO APPEAR TO BE DIMINISHING IN COVERAGE AND THAT SHOULD BE THE TREND THROUGH THE AFTERNOON HOURS. FURTHER EAST AT LSE..MAINLY LOOKING AT A LOW END VFR BKN CLOUD DECK AT 3500-4500FT THROUGH THE AFTERNOON BEFORE SUBSIDENCE KICKS IN AND HELPS CLEAR THE CLOUDS LATER THIS AFTERNOON ON INTO THE EVENING. WINDS WILL REMAIN LIGHT THROUGH THE NIGHT AS A RIDGE AXIS OF HIGH PRESSURE MOVES THROUGH BUT AFTER IT PASSES BY TOMORROW MORNING...THE PRESSURE GRADIENT WILL TIGHTEN UP WITH SOUTHEAST WINDS INCREASING TO 10-20KTS BY LATE MORNING. && .ARX WATCHES/WARNINGS/ADVISORIES... 240 AM CST SAT FEB 16 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...HALBACH LONG TERM...04 AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1003 AM CST SAT FEB 16 2013 .SHORT TERM...THIS MORNING AND AFTERNOON 1003 AM CST SAT FEB 16 2013 CURRENTLY TRACKING A BAND OF LIGHT SNOW MOVING ACROSS SOUTHEAST MINNESOTA AND NORTHEAST IOWA WHICH HAS DROPPED VISIBILITY DOWN TO LESS THAN A MILE AT TIMES. SOME OF THAT MAY BE DUE TO SOME FOG BEING REPORTED IN CENTRAL MINNESOTA...BUT MOST OF THE VISIBILITY REDUCTIONS SHOULD BE DUE TO THE SNOW FALLING. AUSTIN CITY POLICE REPORTED THAT THERE WERE LARGE SNOW FLAKES COMING DOWN AROUND 9AM AND THAT SOME MINOR ACCUMULATIONS WERE BEGINNING. THE FORCING TO PRODUCE THIS SNOW APPEARS TO BE FROM WARM AIR ADVECTION AROUND 925MB ACCORDING TO 16.14Z RAP BUFKIT SOUNDINGS. THESE SOUNDINGS ALSO SHOW THE SATURATED THERMAL PROFILE BEING IN THE PEAK DENDRITIC GROWTH ZONE FROM THE SURFACE UP THROUGH ITS SATURATED LAYER AT ABOUT 4KFT. THE 16.14Z RAP SHOWS THIS AREA OF HIGH LOW LEVEL RELATIVE HUMIDITY AND WARM AIR ADVECTION PROPAGATING TO THE SOUTHEAST THROUGH THE EARLY PART OF THE AFTERNOON BEFORE ENTERING NORTHERN ILLINOIS AFTER 21Z. SO THE PRECIPITATION SHOULD END THEN. BASED ON ALL THIS...UPDATED THE FORECAST TO GO FROM FLURRIES TO THE PERIODS OF SNOW SHOWER THROUGH A PORTION OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA THROUGH 21Z. ALSO ENDED THE FLURRIES AFTER 21Z REGION-WIDE...BUT THAT WILL HAVE TO BE RE-EVALUATED THIS AFTERNOON BASED ON THE CLOUD COVER AT THAT TIME. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY 240 AM CST SAT FEB 16 2013 THIS SYSTEM WILL THEN PULL AWAY FROM THE REGION MONDAY NIGHT AND TUESDAY WITH A LINGERING CHANCE FOR SOME LIGHT SNOW ACROSS THE ENTIRE AREA MONDAY NIGHT AND JUST IN THE I94 CORRIDOR TUESDAY. AS THIS SYSTEM APPROACHES THE EAST COAST OF CANADA...THE MODELS NOW SHOW IS SLOWS CONSIDERABLY WITH RIDGING BUILDING OVER THE CENTRAL PORTIONS OF THE COUNTRY. THE NEXT SYSTEM WILL COME ONSHORE AND INTO THE ROCKIES TO FORM AN OMEGA BLOCK TYPE PATTERN BY WEDNESDAY. HOWEVER...THE SYSTEM COMING IN FROM THE WEST IS EXPECTED TO CONTINUE AN ATTEMPT TO MOVE INTO THE RIDGE AS THERE WILL BE MORE SYSTEMS TOPPING THE PACIFIC RIDGE AND MOVING TOWARD THE ROCKIES. THE MODELS NOW SHOW THE FIRST SYSTEM COMING OUT OF THE WEST TO LIFT INTO THE NORTHERN PLAINS BY FRIDAY AS THE DOWNSTREAM BLOCK REMAINS IN PLACE AND BEGINS TO FILL IN. THIS IS A DRAMATIC SHIFT IN THE UPPER AIR PATTERN FROM PREVIOUS MODEL RUNS WHICH DID NOT SHOW AN OMEGA BLOCK DEVELOPING AND WERE PROGRESSIVE WITH THE SYSTEM. THE SURFACE LOW IS NOW HANDLED QUITE DIFFERENTLY BY THE MODELS WITH THEM SHOWING A VERY DEEP LOW COMING OUT OF THE SOUTHERN ROCKIES WEDNESDAY NIGHT. WITH A FILLING UPPER LEVEL LOW...ALL THE MODELS SHOW THE SURFACE SYSTEM TO BE FILLING AS WELL...BUT TO DIFFERENT DEGREES ON HOW FAST THIS WILL HAPPEN. WOULD HAVE PREFERRED TO LET THE MODEL CONSENSUS GRIDS RIDE UNTIL CONFIDENCE ON HOW THIS SYSTEM WILL EVOLVE BECOMES HIGHER. HOWEVER...UNABLE TO DO THIS AND HAD TO RAISE THE PRECIPITATION CHANCES THURSDAY AFTERNOON AND NIGHT TO REMAIN IN COLLABORATION WITH SURROUNDING OFFICES. ENDED UP WITH 60 PERCENT ACROSS THE SOUTHWEST THURSDAY AFTERNOON ON THE LEADING EDGE OF THE PRECIPITATION SHIELD AND THEN 70 PERCENT FOR MUCH OF THE AREA THURSDAY NIGHT. && .AVIATION...TODAY AND TONIGHT 513 AM CST SAT FEB 16 2013 STRATUS WILL PRODUCE PERIODS OF MVFR CONDITIONS AND FLURRIES AT THE TAF SITES THROUGH THE LATE MORNING HOURS. PLAN ON CLOUD BASES IN THE 2500 TO 3500 FT RANGE. THE STRATUS SHOULD BECOME SCATTERED THIS AFTERNOON AS THE HIGH MOVES IN. HOWEVER...GUIDANCE SUGGESTS THE STRATUS COULD HOLD ON RIGHT ALONG AND EAST OF THE MISSISSIPPI RIVER LATE THIS AFTERNOON INTO THIS EVENING IMPACTING KLSE. THINKING THE STRATUS WILL MIX OUT DURING THE AFTERNOON HOURS BUT WILL HAVE TO KEEP A CLOSE EYE ON THIS. VFR CONDITIONS ARE EXPECTED DURING THE OVERNIGHT HOURS. SCATTERED TO BROKEN MID LEVEL CLOUDS WILL MOVE IN FROM THE WEST LATE TONIGHT AS A STORM SYSTEM MOVES INTO THE NORTHERN PLAINS. WINDS WILL BECOME LIGHT AND VARIABLE TODAY AS THE HIGH MOVES IN. LOOK FOR WINDS TO SWITCH TO THE SOUTHEAST AT 5 TO 10 KTS TONIGHT AS THE HIGH SLIDES EAST OF THE REGION. && .ARX WATCHES/WARNINGS/ADVISORIES... 240 AM CST SAT FEB 16 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...HALBACH LONG TERM...04 AVIATION...WETENKAMP