Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/18/13


AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
339 PM MST MON DEC 16 2013 .SHORT TERM...MODERATE NORTHWEST FLOW ALOFT CURRENTLY OVER THE REGION WITH MID LEVEL JET STREAK MOVING INTO WESTERN WYOMING. COMBINATION OF MIXING AND WEAK MOUNTAIN WAVE KEEPING GUSTY WINDS GOING ACROSS HIGHER MOUNTAINS AND ALONG FOOTHILLS. ALSO A WEAK INVERSION AT MOUNTAIN TOP...THOUGH IT SEEMS IT`S BEING OFFSET BY SOME COLDER AIR AT MID LEVELS. THE MIXING HELPED SPREAD WINDS FURTHER EAST ACROSS URBAN CORRIDOR. SOME GUSTS AROUND 55 MPH WERE OBSERVED IN THE FAVORED TERRAIN. JET STREAK EXPECTED TO MOVE JUST NORTHEAST OF THE AREA DURING THE EVENING...WITH INCREASED SUBSIDENCE BY MIDNIGHT. CROSS SECTIONS SHOWING SOME MID LEVEL WARMING BEHIND THE JET STREAK WHICH SHOULD INCREASE THE MOUNTAIN TOP INVERSION AND ENHANCE THE MOUNTAIN WAVE. LATEST RAP CROSS SECTIONS SHOW THE CROSS MOUNTAIN FLOW INCREASING TO AROUND 40 KTS NEAR MOUNTAIN TOP AFTER MIDNIGHT. THUS...SHOULD SEE WINDS INCREASE ACROSS THE MOUNTAINS AND FOOTHILLS OVERNIGHT. LATEST MODEL GUIDANCE STILL INDICATING THE STRONGER WINDS IN THE MID AND UPPER SLOPES OF THE NORTHERN FOOTHILLS...AND SEEMS REASONABLE BASED ON THE NORTHWEST FLOW ALOFT. SPEEDS TO STAY BELOW HIGH WIND CRITERIA. POTENTIAL FOR OCCASIONAL WESTERLY WINDS SPREADING ONTO THE ADJACENT PLAINS. DID INCREASE THE WINDS SLIGHTLY ALONG THE BASE OF THE FOOTHILLS OVERNIGHT. INCREASED OVERNIGHT TEMPERATURES A FEW MORE DEGREES...ESPECIALLY IN AND NEAR FOOTHILLS WHERE DOWNSLOPE WINDS WILL KEEP TEMPERATURES FAIRLY MILD. ON TUESDAY...FLOW ALOFT BECOMES A BIT MORE WESTERLY AND DECREASES SLIGHTLY. THERE IS SOME WEAK DOWNWARD MOTION...WITH WEAKENING SUBSIDENCE. BUT MIXING IS EXPECTED BY AFTERNOON WHICH WILL HELP KEEP SOME GUSTY WINDS GOING IN AND NEAR FOOTHILLS. ACROSS PLAINS...WEAK SURFACE GRADIENT WILL ALLOW FOR WINDS TO BE LIGHT AND TREND TOWARD DIURNAL TRENDS. TEMPERATURES ACROSS PLAINS TO BE SLIGHTLY COOLER DUE TO LESS DOWNSLOPE FLOW...STILL SHOULD WARM CLOSE TO 60 DEGREES. .LONG TERM...FLOW ALOFT WILL FLATTEN AND BECOME WESTERLY TUESDAY NIGHT AND WEDNESDAY AS AN UPPER LEVEL TROUGH MOVES OVER THE PACIFIC NORTHWEST AND KNOCKS DOWN THE RIDGE OVER THE WESTERN STATES. AIRMASS WILL REMAIN WARM UNDER THE WESTERLY FLOW WITH HIGHS IN THE 60S. MOISTURE AT THE UPPER LEVELS WILL INCREASE...SO EXPECT HIGH CLOUDS TO INCREASE AND COULD HOLD BACK TEMPERATURES SOME IF THICK WAVE CLOUDS FORM. RECORD HIGH FOR WEDNESDAY IS 66 AND COULD BE BROKEN IF ENOUGH SUNSHINE PREVAILS. A WEAK SHORT WAVE TROUGH WILL MOVE ACROSS THE STATE WEDNESDAY NIGHT AS FLOW ALOFT BACKS TO THE SOUTHWEST. WILL HAVE LOW POPS IN THE MOUNTAINS FOR THIS. ELSEWHERE JUST EXPECTED AN INCREASE IN CLOUDS. TEMPERATURES WILL REMAIN MILD WEDNESDAY NIGHT WITH LOWS ABOVE FREEZING MOST LOCATIONS. COLD FRONT WILL MOVE ACROSS NORTHEAST COLORADO THURSDAY MORNING. HIGHS WILL BE REACHED EARLY IN THE DAY AND EXPECT TEMPERATURES TO FALL DURING THE AFTERNOON HOURS. THE COLD AIRMASS IS SHALLOW SO DO NOT EXPECT MUCH IF ANY PRECIPITATION TO FORM DUE TO UPSLOPE WINDS. MODELS SHOWING A BAND OF PRECIPITATION FORMING OVER NORTHWEST COLORADO AND INTO WYOMING DUE TO THE JET. THE NORTH CENTRAL MOUNTAINS WILL HAVE A GOOD CHANCE AT SEEING SOME OF THE SNOW...BUT ELSEWHERE CHANCES ARE LOW. THE SNOW THAT DOES FALL IS EXPECTED TO BE LIGHT. MAIN LOW DIVES SOUTH AND CUTS OFF OVER NORTHERN MEXICO AND THE MAIN JET STAYS TO OUR NORTH LEAVING THE AREA UNDER A WEAK FLOW ALOFT FRIDAY AND SATURDAY. THERE WILL BE ANOTHER CHANCE/SLIGHT CHANCE OF SNOW AS THE TROUGH AXIS MOVE ACROSS COLORADO SATURDAY. THOUGH IF ANY SNOW FORMS IT WILL BE LIGHT. THE MOUNTAINS WILL HAVE THE BEST CHANCE FOR SNOW DUE TO OROGRAPHIC LIFT. TEMPERATURES WILL BE COOL FRIDAY AND SATURDAY WITH HIGHS IN THE 30S OVER NORTHEAST COLORADO. NORTHWEST FLOW ALOFT WILL PREVAIL SUNDAY AND MONDAY AS THE MAIN TROUGH SHIFTS EAST OF COLORADO AND A RIDGE DEVELOPS ALONG THE WEST COAST. TEMPERATURES WILL WARM A LITTLE SUNDAY AND MONDAY. MAY BE ENOUGH MOISTURE EMBEDDED IN THE NORTHWEST FLOW ALOFT TO PRODUCE LIGHT SNOW AT TIMES ALONG AND WEST OF THE CONTINENTAL DIVIDE. && .AVIATION... && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....MEIER AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1009 AM MST MON DEC 16 2013 .UPDATE... && .SHORT TERM...WINDS BEEN A BIT GUSTY IN AND NEAR FOOTHILLS DUE TO MIXING AND SUBSIDENCE WITH NORTHWEST FLOW ALOFT. SOUNDINGS INDICATING PERSISTENT MOUNTAIN TOP INVERSION. JET STREAK CURRENTLY MOVING ACROSS WYOMING HELPING WITH SUBSIDENCE OVER COLORADO. THERE MAY BE SOME DECREASE IN THE WINDS THIS AFTERNOON AS A BIT OF COLD AIR ADVECTION WEAKENS THE INVERSION. CURRENT WIND FORECASTS SEEM REASONABLE FOR NOW...BUT WILL INCLUDE A BIT MORE WIND TO URBAN CORRIDOR FOR THIS AFTERNOON BASED ON CURRENT OBSERVATIONS AND EXPECTED MIXING. MOUNTAIN WAVE MAY BE AMPLIFIED OVERNIGHT WITH SOME WARM AIR ADVECTION...WITH POTENTIAL FOR STRONGER WIND GUSTS. NO WIND HILITIES EXPECTED AT THIS TIME...SPEEDS SHOULD REMAIN BELOW CRITERIA. .AVIATION...NORTHWEST WINDS OCCURRING ACROSS AREA AIRPORTS...WOULD EXPECT THIS TREND TO CONTINUE THROUGH THE AFTERNOON AS NORTHWEST WINDS ALOFT CONTINUE TO MIX TO THE SURFACE. THE RAP AND HRRR DO INDICATE WEAK ANTICYCLONE DEVELOPING NORTH OF DENVER DURING THE AFTERNOON...WITH LIGHT NORTHEAST WINDS AT KDEN. FEEL THIS WILL BE SHORT LIVED DUE TO THE EXPECTED MIXING. WILL CONTINUE TREND OF CURRENT TAFS. && .PREV DISCUSSION... /ISSUED 423 AM MST MON DEC 16 2013/ SHORT TERM...NORTHWESTERLY FLOW ALOFT WILL CONTINUE OVER COLORADO TODAY. MODELS HAVE STRUGGLED A BIT WITH THE LITTLE RIPPLES IN THE FLOW...AND HAVE TRIED TO DECREASE THE WINDS A BIT TOO QUICKLY. SUSPECT THIS WILL STILL BE THE CASE TODAY AS ANOTHER JET STREAK SLIDES JUST NORTHEAST OF US. THERE IS A LITTLE COLD ADVECTION ALOFT TODAY...THEN WARM ADVECTION AGAIN BEHIND THE JET STREAK BY THIS EVENING. THIS SHOULD CREATE A MORE FAVORABLE TEMPERATURE PROFILE FOR AN AMPLIFIED MOUNTAIN WAVE AGAIN SO DESPITE THE VERY GRADUAL DECREASING GRADIENT...THERE MAY ACTUALLY BE STRONGER GUSTS OVERNIGHT. BLENDED IN THE LATEST WIND GUIDANCE WHICH FOCUSES THE WINDS MORE IN THE MID TO UPPER SLOPES OF THE FRONT RANGE OVERNIGHT WHICH IS PROBABLY ALRIGHT...BUT THE WINDS WILL PROBABLY ALSO SPILL INTO THE BOULDER AREA AT TIMES SINCE THE COLD AIR HAS BEEN PRETTY WELL DISPLACED. I WARMED TEMPERATURES SLIGHTLY IN LIGHT OF THE CURRENT READINGS...GFS LOOKS TOO WARM BUT NAM SEEMS NOT TO KNOW THAT THE SURFACE COLD AIR IS GONE. ALSO ADDED A BIT MORE CLOUD COVER AS WAVE CLOUDS WILL LIKELY COME AND GO. LONG TERM...MODELS HAVE NORTHWESTERLY FLOW ALOFT BECOMING WEST- NORTHWESTERLY FROM TUESDAY AT 12Z THROUGH WEDNESDAY AT 12Z. A FLATTENING UPPER RIDGE AXIS MOVES ACROSS THE CWA ON WEDNESDAY AND THE FLOW ALOFT BECOMES SOUTHWESTERLY BY WEDNESDAY NIGHT LATE. AT 12Z THURSDAY MORNING...THE MODELS SHOW AN UPPER TROUGH JUST GETTING INTO THE NORTHWESTERN GREAT BASIN. WEAK DOWNWARD QG VERTICAL VELOCITY IS PROGGED FOR THE CWA TUESDAY INTO WEDNESDAY. BY WEDNESDAY AFTERNOON...WEAK UPWARD MOTION IS INDICATED...WHICH CONTINUES WEDNESDAY NIGHT. THE BOUNDARY LAYER WINDS CONTINUE TO HAVE A DOWNSLOPING COMPONENT TO THEM TUESDAY INTO MID DAY WEDNESDAY. NORMAL DIURNAL PATTERNS THEN KICK IN. THE GFS AND CANADIAN BRING A COLD FRONT INTO THE NORTHEAST BY 12Z THURSDAY MORNING...THE ECMWF KEEPS SHOWING IT MOVE IN ON THURSDAY. FOR MOISTURE...IT IS DRY TUESDAY AND TUESDAY NIGHT. THERE IS SOME UPPER LEVEL MOISTURE PROGGED ON WEDNESDAY...THEN LATE WEDNESDAY NIGHT...MOISTURE STARTS MOVING INTO THE WESTERN CWA IN EARNEST DUE TO THE NEXT UPPER TROUGH. THERE IS A TAD OF MEASURABLE PRECIPITATION OVER THE HIGH MOUNTAINS WEST OF THE DIVIDE BY THURSDAY MORNING. NO POPS TUESDAY THROUGH WEDNESDAY NIGHT. FOR TEMPERATURES...TUESDAY`S HIGHS ARE 1-3 C WARM THAN TODAY`S EXPECTED HIGHS. WEDNESDAY`S HIGHS ARE UP ANOTHER 1-3 C OVER TUESDAY`S. FOR THE LATER DAYS...THURSDAY THROUGH SUNDAY...MODELS HAVE WEST-SOUTHWESTERLY FLOW ALOFT ON THURSDAY WITH AN UPPER TROUGH DEVELOPING OVER THE GREAT BASIN. SOUTHWESTERLY FLOW ALOFT IS PROGGED FRIDAY WITH THE UPPER TROUGH AXIS OVER WESTERN COLORADO LATE FRIDAY AFTERNOON. THE UPPER TROUGH AXIS IS NOT PROGGED TO PUSH EASTWARD ACROSS THE CWA UNTIL SATURDAY AFTERNOON AND NIGHT. ON SUNDAY...NORTH-NORTHWESTERLY FLOW ALOFT IS PROGGED FOR COLORADO. THE STORMS AND THE COLD AIR IS NOT SIGNIFICANT ACCORDING TO THE LATEST RUNS. AVIATION...VFR THROUGH TONIGHT. WESTERLY WINDS WILL PREVAIL...WITH GUSTS TO 30 KNOTS AT KBJC AND 20 KNOTS AT KDEN...PROBABLY LIGHTER AT KAPA. TREND MAY BE A BIT MORE NW DURING THE DAY...THEN BACK TO MORE SW THIS EVENING. MOUNTAIN WAVE ACTIVITY TO THE WEST COULD EVEN BRING PERIODS OF S TO SE WINDS TONIGHT...THOUGH THIS IS UNCERTAIN. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....RJK AVIATION...D-L
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
953 PM EST TUE DEC 17 2013 .SYNOPSIS... A LOW PRESSURE SYSTEM JUST OFF THE DELMARVA COAST WILL MOVE NORTHEAST AND BE EAST OF THE NEW ENGLAND COAST BY WEDNESDAY MORNING. AN UPPER AIR DISTURBANCE WILL MOVE THROUGH THE DELMARVA OVERNIGHT INTO WEDNESDAY MORNING. A HIGH PRESSURE SYSTEM WILL NOSE BACK IN FROM THE WEST FOR THE MIDDLE OF THE WEEK. A COLD FRONT SHOULD REACH THE GREAT LAKES ON FRIDAY AND SLOWLY SAG AND THEN STALL OVER OR JUST NORTH OF THE FORECAST AREA ON THE WEEKEND. THE FRONT SHOULD THEN START MOVING THROUGH THE FORECAST AREA LATE SUNDAY OR ON MONDAY. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... HAVE CONTINUED TO UPDATE OVERNIGHT LOW TEMPERATURES BASED ON THE LATEST OBSERVATIONS OVER THE NORTHWEST PART OF THE AREA WHERE THE BEST RADIATIONAL COOLING HAS OCCURRED. NO CHANGES TO THE EARLIER UPDATE AROUND 730 PM TO INTRODUCE SNOW ACCUMULATIONS UNDER AN INCH IN THE DELMARVA AND SOUTHERN NJ WITH THE LAST SHORTWAVE MOVING THROUGH THE AREA. THESE ACCUMULATIONS ARE SOMEWHAT LOWER THAN THE LATEST HRRR MODEL OUTPUT, BUT THE HRRR HAS BEEN TRENDING LOWER. HRRR RUNS IN THE LATE AFTERNOON SHOWED SOME LOCATIONS WITH 3+ INCHES OF SNOW, BUT LATEST HRRR HAS MAX SNOW ACCUMULATIONS IN THE 1 TO 2 INCH RANGE. SINCE THE HRRR IS TRENDING OUR WAY, AND THERE IS NOTHING IN THE CURRENT OBSERVATIONS TO SUGGEST MORE SIGNIFICANT SNOWFALL SHOULD BE EXPECTED, WE`LL HOLD WITH WHAT WE`VE GOT IN THE FORECAST. ALL PRECIPITATION SHOULD CLEAR THE COAST AND BE MOVING OUT TO SEA BY 08Z. ELSEWHERE IN THE FORECAST AREA, TEMPERATURES HAVE DROPPED BELOW FREEZING. FOG HAS DEVELOPED IN SOME LOCATIONS, AND MANY SPOTS WHERE MELTING OCCURRED EARLIER TODAY ARE NOW DEALING WITH BLACK ICE. AN SPS HAS BEEN ISSUED. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... HIGH PRESSURE TO THE WEST WILL BEGIN TO BUILD IN WED. SKIES WILL BE MOSTLY SUNNY AND A GUSTY WEST TO NORTHWEST WINDS WILL BE ACROSS THE AREA. HIGH TEMPERATURES WILL BE IN THE UPPER 20S TO LOW 30S NORTH AND LOW/MID 30S ACROSS PHILADELPHIA AND THE DELMARVA. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... THE LONGTERM WILL START OUT RATHER BENIGN GIVING US A MUCH NEEDED REPRIEVE FROM THE CURRENT MESS THAT OUR WINTER HAS QUICKLY BECOME. LONGWAVE TROUGHING WILL BE WELL EAST OF THE REGION AS FLAT RIDGING PUNCHES IN FROM THE WEST ON WEDNESDAY NIGHT. NO MATTER AS WE SHOULD BE PRECIPITATION FREE FOR A COUPLE DAYS ALL THE WHILE TEMPERATURES START TO MODERATE TOWARDS THE ABOVE NORMAL SPECTRUM BY THE END OF THE WORK WEEK UNDER DEEP LAYER SOUTHWEST FLOW. SPLIT FLOW ALOFT WILL KEEP A MAJORITY OF THE ENERGY WELL TO OUR NORTH AND SOUTHWEST AS SOUTHEAST RIDGING STRENGTHENS BY FRIDAY AND SATURDAY. CLOSED LOW ACROSS THE FOUR CORNERS WILL BEGIN TO LIFT INTO THE CENTRAL PLAINS WITH A CONFLUENT ZONE ACROSS THE OHIO VALLEY SATURDAY AND SUNDAY. STRONGER DEEP LAYER SOUTHWEST FLOW REALLY BUMPS UP TEMPERATURES AND PWATS BY THE WEEKEND...CLOSE TO +3SD ON THE PWATS...THE GULF IS OPEN. THIS COULD POSE ISSUES (SMALL STREAM FLOODING) THIS WEEKEND WITH AS A SLOW MOVING FRONTAL BOUNDARY SINKS SOUTHWARD INTO OUR CWA, THOUGH ITS EXACT POSITIONING/TIMING STILL PROVIDES PLENTY OF SPREAD WITHIN THE GUIDANCE ENVELOPE. THE GFS IS FASTER AND PUSHES THE FRONT THROUGH ON SUNDAY NIGHT WHILE THE THE EC KEEPS IT HUNG UP TO OUR NORTH LONGER ULTIMATELY CLEARING OUR AREA LATE MONDAY NIGHT. DID SLOW THE TIMING OF THE POPS DOWN A BIT FROM THE PREVIOUS RUNS WITH THE FRONTAL ZONE PARALLEL TO THE FLOW ALOFT. AHEAD OF THE FRONT, WHEREVER IT LIES, AT LEAST THE SOUTHERN HALF OF THE CWA WILL BE IN A MODIFYING WARM SECTOR. SOME OF THE EXTENDED GUIDANCE IS REALLY CRANKING UP THE TORCH LATE THIS WEEKEND WHICH WOULD EASILY GIVE US RECORD TEMPERATURES. THIS ASSUMES MIXING UP TO 850MB AND A CLEAN WARM SECTOR, BOTH OF WHICH IS HARD TO DO IN THE MIDDLE OF DECEMBER. THE DETERMINISTIC EC IS THE MOST ROBUST GUIDANCE WITH ITS THERMAL FIELDS THIS WEEKEND, AND FROM WHAT WAS SEEN OFF ITS 00Z ENSEMBLE MEAN (12Z WAS NOT AVAILABLE IN TIME) DIDN`T HAVE THE SUPPORT THAT THE GFS/GEFS DID. FOR THE MOST PART WE USED A BLEND OF THE NEW WPC LONGTERM GUIDANCE AND OUR PREVIOUS FORECAST, WHICH KEEPS MOST THINGS UNCHANGED GIVEN THE UNCERTAINTY OF THE FRONTAL POSITION LATE THIS WEEK/WEEKEND. DID INCREASE TEMPERATURES A BIT ABOVE WPC THIS WEEKEND AND IT LOOKS LIKE 60S ARE WELL WITHIN REACH. TEMPERATURES WILL DROP BACK TOWARDS NORMAL OR BELOW BY TUESDAY DEPENDING THE TIMING OF THE FRONTAL PASSAGE. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. OVERNIGHT...STILL HAVE A THREAT OF PRECIPITATION IN THE KMIV TAF WITH THE LAST PART OF THE STORM SYSTEM MOVING THROUGH. THE PRECIPITATION THREAT SHOULD BE OVER BY 08Z. ELSEWHERE THERE ARE LOCALIZED IFR/MVFR CONDITIONS IN FOG AND LOW CLOUDS, BUT CONDITIONS HAVE IMPROVED SLIGHTLY OVER THE PAST HOUR. RESTRICTIONS IN FOG AND LOW CLOUDS SHOULD IMPROVE AFTER 09Z AS WINDS INCREASE FROM THE NORTHWEST. WED...VFR CONDITIONS EXPECTED WITH WEST TO NORTHWEST WINDS GUSTING TO AROUND 20 KTS. OUTLOOK... WEDNESDAY NIGHT - THURSDAY...VFR WITH SOUTHWEST WINDS. FRIDAY...MOSTLY VFR. CHANCE OF MVFR CONDITIONS NORTHWEST. SOME GUSTY SOUTHWEST WINDS POSSIBLE ON THE COASTAL PLAIN AIRPORTS. FRIDAY NIGHT AND SATURDAY...MAINLY VFR. SOME MVFR CONDITIONS IN SHOWERS WITH A GREATER CHANCE/CONFIDENCE NORTHERN AIRPORTS. && .MARINE... AN INTENSIFYING LOW PRESSURE AREA WILL MOVE OFF THE MID ATLANTIC COAST OVERNIGHT. AS THE STORM BEGINS TO PULL AWAY...WINDS WILL SWING AROUND TO NORTH/NORTHWEST AND STEADILY INCREASE IN SPEED. SMALL CRAFT FLAGS BEGIN OVER THE OCEAN WATERS AT MIDNIGHT AND ON THE DEL MAY TOWARDS DAWN. NO CHANGE HAS BEEN MADE ON THIS TIMING. OUTLOOK... WEDNESDAY NIGHT...SUB-SCA CONDITIONS SHOULD DEVELOP AS WE LOSE THE STRONGER WINDS AND SEAS BEGIN TO SUBSIDE BELOW 5 FEET. CONFIDENCE IS MEDIUM. THURSDAY THROUGH SATURDAY...AN INCREASING RETURN SOUTHWEST FLOW. THERE IS A CHANCE FOR SMALL CRAFT ADVISORY CONDITIONS THROUGH THE PERIOD. THE LIMITING FACTOR MAY BE THAT THE AIR MASS WILL BE BECOMING WARMER THAN THE OCEAN AND BAY WATERS. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST WEDNESDAY FOR ANZ450>455. SMALL CRAFT ADVISORY FROM 5 AM TO 6 PM EST WEDNESDAY FOR ANZ430-431. && $$ SYNOPSIS...SZATKOWSKI/HEAVENER NEAR TERM...SZATKOWSKI/O`HARA SHORT TERM...O`HARA LONG TERM...HEAVENER AVIATION...SZATKOWSKI/HEAVENER/O`HARA MARINE...SZATKOWSKI/HEAVENER/O`HARA
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
824 PM EST TUE DEC 17 2013 .SYNOPSIS... A DRY COLD FRONT WILL MOVE ACROSS THE REGION TONIGHT. HIGH PRESSURE WILL BUILD ACROSS THE REGION WEDNESDAY THEN SLIDE OFF THE SOUTHEAST COAST THURSDAY. A SOUTHERLY FLOW WILL BRING MUCH ABOVE NORMAL TEMPERATURES TO THE AREA FOR THE WEEKEND. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... BASED ON LATEST RAP MODEL...DRY COLD FRONT EXPECTED TO MOVE THROUGH THE REGION BETWEEN 05Z AND 08Z. WINDS MAY BE GUSTY AS FRONT MOVES THROUGH THEN DIMINISH TOWARD DAYBREAK. LOW TEMPERATURES EXPECTED TO FALL INTO THE LOW TO MID 30S. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/... BY SUNRISE WEDNESDAY THE COLD FRONT WILL BE WELL OFF THE COAST. HIGH PRESSURE WILL BUILD INTO REGION FROM THE WEST. OUR AIR MASS WILL REMAIN DRY. UNDER SUNNY SKIES...SHOULD SEE TEMPERATURES WARM INTO THE 50S. THE AREA OF HIGH PRESSURE WILL BE CENTERED OVER THE AREA WEDNESDAY NIGHT. THERE MAY BE SOME HIGH CLOUDINESS AS THE UPPER RIDGE FLATTENS BUT EXPECT THIS CLOUDINESS WILL BE THIN AND STRONG NET RADIATIONAL COOLING SHOULD OCCUR. GUIDANCE TEMPERATURES WERE CONSISTENT WITH LOWS IN THE MID 20S TO LOWER 30S. WARMING SHOULD BEGIN THURSDAY AS THE HIGH SHIFTS OFF THE COAST AND A SOUTHERLY FLOW DEVELOPS. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... RETURN FLOW ON THE WEST SIDE OF HIGH PRESSURE OFF THE SOUTHEAST COAST WILL BRING INCREASING MOISTURE AND WARMER TEMPERATURES TO THE AREA INTO THE WEEKEND. RAPIDLY INCREASING MOISTURE WILL LIKELY RESULT LOW MORNING STRATUS FRIDAY AND SATURDAY. TEMPERATURES WILL INCREASE TO MUCH ABOVE NORMAL BY SUNDAY WITH MORNING LOWS NEAR 60 AND HIGHS IN THE MID TO UPPER 70S. A COLD FRONT WILL APPROACH THE AREA FROM THE WEST ON SUNDAY AND CROSS THE AREA SUNDAY NIGHT INTO MONDAY. WILL INCREASE POPS TO THE 60 TO 70 PERCENT RANGE WITH THE FRONTAL PASSAGE. WITH WARM MOIST AIR AT LOW LEVELS...A 40 TO 50 KT LOW LEVEL JET...AND SLIGHTLY UNSTABLE LI VALUES...SOME CONVECTION IS POSSIBLE WITH THIS FRONTAL PASSAGE. WILL HAVE TO WATCH THIS AS WE GET CLOSER TO THE EVENT. DRIER AND COLDER AIR WILL MOVE IN BEHIND THE FRONT MONDAY AFTERNOON INTO TUESDAY. WHILE THE TREND FOR INCREASING TEMPERATURES AND DEWPOINTS IS HIGH CONFIDENCE...THE DETAILS ARE TOUGH TO NAIL DOWN DUE TO THE POTENTIAL FOR MORNING STRATUS ON FRIDAY AND SATURDAY. CONFIDENCE FOR RAIN WITH THE FRONTAL PASSAGE IS ABOVE AVERAGE. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE FORECAST PERIOD. A DRY COLD FRONT WILL CROSS THE REGION DURING THE 04Z-08Z TIME FRAME TURNING SOUTHWESTERLY WINDS NORTHWESTERLY AROUND 5 TO 10 MPH. SOME POSSIBLE CIRRUS CLOUDS PASSING EARLY IN THE PERIOD...OTHERWISE CLEAR SKIES THROUGH THE FORECAST. EXTENDED AVIATION OUTLOOK...INCREASING LOW LEVEL MOISTURE COMBINED WITH NOCTURNAL COOLING COULD ALLOW MVFR/IFR CIGS/FOG TO DEVELOP DURING THE LATE NIGHT AND EARLY MORNING HOURS FRIDAY THROUGH SUNDAY. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
846 PM CST TUE DEC 17 2013 .DISCUSSION... 845 PM CST FOR EVENING UPDATE... MINOR TWEAKS TO NEAR TERM GOING FORECAST THIS EVENING...MAINLY TO RAISE MIN TEMPS A LITTLE OVERNIGHT AND TO TWEAK SKY COVER THIS EVENING BASED ON SATELLITE TRENDS. HIGHLY SHEARED MID-LEVEL SHORT WAVE NOTED IN FAST NORTHWEST FLOW ALOFT PER RAOB/GOES VAPOR IMAGERY ACROSS THE AREA EARLY THIS EVENING...WITH 85-95 KT H5 SPEED MAX NOTED IN MPX-DVN-ILX RAOBS. REGIONAL RADAR MOSAIC HAS BEEN DEPICTING AN AREA OF VERY LIGHT SNOW AND FLURRIES ACROSS SOUTHERN WI AND FAR NORTHEAST IL THIS EVENING IN ASSOCIATION WITH THIS FEATURE...WITH AN AREA OF BKN-OVC CLOUD COVER AS FAR SOUTH AS THE STREATOR-KANKAKEE-REMINGTON AREAS. MODEL GUIDANCE PICKS UP ON THIS SHEARED WAVE...MOVING IT QUICKLY EAST OF THE AREA BY/AFTER 06Z. THIS SHOULD ALLOW CLEARING FROM THE WEST DURING THE LATE EVENING/OVERNIGHT HOURS...WITH BACK EDGE OF LOWER CLOUDS NOW ROUGHLY MONROE WI-PERU IL. SOME PATCHY CIRRUS WILL CONTINUE TO SPILL IN FROM THE NORTHWEST IN ASSOCIATION WITH UPPER JET. BRISK WEST-NORTHWEST WINDS WILL DECREASE AFTER MIDNIGHT... AS SURFACE RIDGE AXIS NOW OVER IA-MN BUILDS EAST IN RESPONSE TO RISING HEIGHTS ALOFT IN WAKE OF DEPARTING UPPER TROUGH. DESPITE LIGHTER WINDS...CLEARING SKIES AND SNOW COVER...WARM ADVECTION IS ALREADY DEVELOPING ALOFT WEST OF THE MISSISSIPPI RIVER AS WINDS BACK TO THE WEST-SOUTHWEST WITH APPROACHING WARM FRONT. SURFACE DEW POINTS HOLDING IN THE LOW-MID TEENS ACROSS THE REGION AND THOUGH THEY WILL LIKELY DROP A LITTLE BIT...HAVE BUMPED UP FORECAST MINS 1-2 DEG ACROSS THE CWA TO NEAR 10 (WITH ARR/RPJ STILL IN UPPER SINGLE DIGITS) ACROSS NORTH CENTRAL IL...AND TEENS MAINLY ELSEWHERE. OTHERWISE...ONLY CHANGE WAS TO INCREASE CLOUD COVER PERCENTAGE IN SKY GRIDS A BIT WITH THE AFOREMENTIONED PATCH OF BKN-OVC CLOUDS CURRENTLY OVER THE CWA. REMAINDER OF FORECAST APPEARS IN GOOD SHAPE THROUGH TOMORROW. RATZER && .PREV DISCUSSION... 327 PM CST A VERY ACTIVE WEATHER PATTERN IS EXPECTED THROUGH THE WEEKEND WITH A PLETHORA OF CONCERNS...INCLUDING PRECIP TIMING...TYPES AND AMOUNTS...ESPECIALLY WITH THE WEEKEND SYSTEM. AFTER ANOTHER CHILLY NIGHT TONIGHT UNDER PARTLY CLOUDY SKIES...SOUTHWESTERLY WINDS WILL PICK UP...PRODUCING A WARMER DAY ACROSS THE REGION FOR WEDNESDAY. IT APPEARS THAT TEMPERATURES WILL CLIMB AT LEAST A COUPLE OF DEGREES ABOVE FREEZE ACROSS THE WHOLE AREA. UNFORTUNATELY...THE EXTENSIVE SNOW PACK WILL KEEP TEMPERATURES FOR WARMING MORE...AT LEAST UNTIL THURSDAY. THE GUIDANCE IS HAVING TROUBLE WITH AGREEING ON THE PLACEMENT OF A FRONTAL ZONE ON THURSDAY. THE NCEP MODELS...NAMELY THE GFS AND NAM SUGGEST THAT THIS BOUNDARY WILL SAG SOUTHWARD TO NEAR THE I-80 CORRIDOR DURING THE DAY ON THURSDAY. THIS SOLUTION WOULD FAVOR COOLER TEMPERATURES NEAR FREEZING ACROSS FAR NORTHERN ILLINOIS ON THURSDAYS. HOWEVER...THE ECMWF SUGGESTS THAT THIS FRONT WILL REMAIN ACROSS FAR SOUTHERN WISCONSIN...WITH SOUTHERLY FLOW AND WARMER CONDITIONS CONTINUING. I HAVE CHOSEN TO FOLLOW CLOSER TO THE ECMWF AS IT APPEARS THAT THE SURFACE LOW...WHICH THE FRONTAL ZONE EMANATES FROM...ACROSS THE UPPER GREAT LAKES REGION IS BEING OVERDONE A BIT BY THE NCEP MODELS...AND AS A CONSEQUENCE THEY DRIVE THE FRONT A BIT FARTHER SOUTH ACROSS NORTHERN ILLINOIS. OVERALL...THE ECMWF WOULD SUGGEST MUCH LESS OF A THREAT OF FREEZING DZ/RAIN AND LIKELY KEEP IT LIQUID WITH SURFACE TEMPS ABOVE FREEZING. THE ONLY EXCEPTION TO THIS MAY BE ACROSS FAR NORTHERN ILLINOIS. OVERALL...THE INCREASE IN LOW LEVEL MOISTURE TO THE SOUTH OF THE FRONTAL ZONE WILL LIKELY LEAD TO LOW CLOUDS AND EVEN FOG ACROSS MUCH OF THE AREA LATER THURSDAY INTO THURSDAY NIGHT. A SURFACE WAVE IS FORECAST TO MOVE ALONG THE FRONTAL ZONE THURSDAY NIGHT INTO FRIDAY...AND THIS FINALLY ALLOW THE FRONT TO SHIFT SOUTHWARD ACROSS THE AREA BY FRIDAY. IT APPEARS ISENTROPIC ASCENT WILL PRODUCE SOME LIGHT PRECIP IN ASSOCIATION WITH THIS SURFACE WAVE THURSDAY NIGHT INTO FRIDAY. AS THE COLD AIR BEGINS TO FILTER SOUTHWARD IT APPEARS THE PRECIP COULD EITHER CHANGE OVER TO A PERIOD OF LIGHT SNOW...OR FREEZING DRIZZLE. SOME OF THE FORECAST SOUNDINGS INDICATE THAT THE DENDRITIC GROWTH ZONE WILL BE VOID OF DECENT MOISTURE...WHICH WOULD FAVOR FREEZING DRIZZLE OVER LIGHT SNOW. I HAVE MENTIONED A SNOW OR LIGHT FREEZING DRIZZLE CHANCE OVER NORTHERN ILLINOIS LATE THURSDAY NIGHT INTO FRIDAY MORNING TO COVER THIS POTENTIAL. OTHERWISE ATTENTION TURNS TO THE SYSTEM EXPECTED TO DIG ACROSS THE SOUTHWEST..NEAR BAJA CALIFORNIA BY FRIDAY NIGHT. THIS DIGGING SYSTEM IS EXPECTED TO TRANSITION A QUASI-ZONAL FLOW PATTERN ACROSS THE CONUS INTO A SOUTHWESTERLY FLOW PATTERN ALOFT...AS DOWNSTREAM HEIGHT RISES LEAD TO POSITIVE HEIGHT ANOMALIES AND RIDGING ACROSS THE EASTERN CONUS. THIS PATTERN IS VERY CONDUCIVE TO PRODUCING A SIGNIFICANT PRECIP EVENT ACROSS PORTIONS OF THE CENTRAL CONUS. A STRONG AND IMPRESSIVE SOUTHERLY 60+ KT LOW LEVEL JET IS PROGGED TO DEVELOP BY SATURDAY IN RESPONSE TO THE PATTERN SHIFT...WITH LOW PRESSURE DEVELOPING ACROSS TEXAS. THIS LOW LEVEL JET WILL TRANSPORT COPIOUS AMOUNTS OF MOISTURE NORTHWARD ACROSS THE MISSISSIPPI AND OHIO VALLEYS. OVERALL...THIS CONTINUES TO BE A VERY COMPLEX FORECAST AS THE SYSTEM APPEARS THAT IT WILL...AT LEAST TEMPORALLY...SEPARATE ITSELF FROM THE MAIN SOUTHERN STREAM FLOW. MUCH OF THE GUIDANCE IS IN FAIR AGREEMENT WITH TAKING THIS SYSTEM EAST-NORTHEASTWARD ACROSS THE TEXAS PANHANDLE LATE SATURDAY AND THEN MERGING BACK INTO THE MAIN TROUGH BY SUNDAY AS IT MOVES ACROSS MISSOURI. OVERALL...IN THE LOWER LEVELS...THIS LOOKS TO SET UP A FRONTAL BOUNDARY RIGHT ACROSS THE CENTRAL STATES...WITH AN ELONGATED AREA OF SURFACE LOW PRESSURE LIKELY TO TRANSITION ALONG THE BOUNDARY THROUGH THE WEEKEND. STRONG MOISTURE CONVERGENCE AND FRONTOGENESIS IS LIKELY IN THE VICINITY OF THE SOUTHWEST TO NORTHEAST ORIENTED BOUNDARY...ALONG THE NOSE OF THE LOW LEVEL JET. THIS WILL LIKELY RESULT IN HEAVY PRECIPITATION ACROSS AT LEAST PORTIONS OF THE AREA LATE SATURDAY INTO SUNDAY. THE MAIN QUESTIONS AT THIS POINT CONTINUE TO BE...WHAT FORM WILL THE PRECIP BE? I CONTINUE TO FOLLOWER CLOSER TO THE ECMWF SOLUTION FOR THE SYSTEM AS IT HAS BEEN VERY GOOD LATELY. THE MAIN CONCERNS I HAVE IS THE THERMAL PROFILE WITH THIS SYSTEM. IT IS POSSIBLE THAT THE PRECIP BEGINS AS A WINTER MIX OF RAIN FREEZING RAIN SLEET AND SNOW...ESPECIALLY ACROSS THE NORTH. MY SOUTHERN COUNTIES MAY BECOME WARM ENOUGH TO RESULT IN MAINLY RAIN...AT LEAST THROUGH SATURDAY NIGHT. THERE ARE DEFINITELY SIGNS THAT THIS SYSTEM COULD TRANSITION OVER TO FREEZING RAIN AND THEN SNOW SATURDAY NIGHT ACROSS NORTHERN ILLINOIS AS THE SYSTEM TRYS TO PULL IN COLDER AIR IN THE LOWER LEVELS FOR THE NORTH. SIGNIFICANT ACCUMULATIONS ARE CERTAINLY POSSIBLE ACROSS PORTIONS OF NORTHERN ILLINOIS. HOWEVER...THE THERM PROFILE...AND HENCE WHERE SNOW VERSE RAIN WILL FALL COULD EASILY CHANGE IN FUTURE FORECASTS. SO...IN SPITE OF THE FACT CONFIDENCE IS INCREASING THAT WE WILL SEE A DECENT PRECIP EVENT ACROSS THE AREA. CONFIDENCE ON PRECIP TYPE...AND WHERE THE RAIN/VERSES HEAVY SNOW LINE SETS UP REMAINS LOW AT THIS TIME. FOR THESE REASONS...IT IS TOO EARLY TO START MENTIONING AMOUNTS OF SNOW OR ICE FOR ANY GIVEN AREAS. THE AMOUNT OF PRECIP WITH THIS SYSTEM COULD CAUSE HYDRO ISSUES...WITH PRECIP AMOUNTS POSSIBLY EXCEEDING AN INCH OR TWO ACROSS PORTIONS OF THE AREA. THIS WILL HAVE TO BE WATCHED...ESPECIALLY IF THE PRECIP FALLS AS RAIN ON TOP OF ANY REMAINING SNOW PACK. ANOTHER SHOT OF COLDER AIR WILL OVERSPREAD THE AREA EARLY NEXT WEEK IN THE WAKE OF THIS SYSTEM...WITH HIGH PRESSURE BUILDING IN ACROSS THE REGION. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 00Z... * VFR CEILINGS THIS EVENING...THEN CLEARING. * GUSTY SOUTHWEST WINDS WEDNESDAY. * FOG WITH LOW END MVFR CONDITIONS DEVELOPING LATE IN THE PERIOD. * POSSIBLE IFR CEILINGS AND FREEZING DRIZZLE LATE IN THE PERIOD. RODRIGUEZ //DISCUSSION...UPDATED 00Z... OUTSIDE OF AN ISOLATED AREA OF FLURRIES NORTH OF THE TERMINALS...RATHER QUIET CONDITIONS ONGOING ACROSS THE AIRPORT THIS EVENING. LINGERING VFR CEILINGS WILL CONTINUE TO MOVE OVERHEAD THIS EVENING BEFORE DEPARTING TO THE EAST OVERNIGHT. QUIET/VFR CONDITIONS EXPECTED FOR MOST OF THE FORECAST PERIOD WEDNESDAY. AN APPROACHING SURFACE RIDGE WILL QUICKLY MOVE EAST THROUGH THE REGION WITH WINDS BACKING TO THE SOUTHWEST WEDNESDAY MORNING...WITH SPEEDS/GUSTS INCREASING THROUGH THE AFTERNOON. A WARMER AND MORE MOIST AIR MASS IS EXPECTED TO MOVE NORTH ACROSS THE REGION ON WEDNESDAY. THIS INCREASE IN MOISTURE WILL AID IN THE DEVELOPMENT OF FOG AND LOW CEILINGS WEDNESDAY NIGHT. HAVE TRENDED THIS WAY WITH THE ORD TAF...INDICATING LOW END MVFR CONDITIONS BY THE EVENING. CONDITIONS WILL FURTHER DETERIORATE WEDNESDAY NIGHT WITH IFR CONDITIONS LIKELY...BUT WITH LOW CONFIDENCE ON EXACT TIMING THE ONLY REASON FOR LEAVING THIS OUT OF THE TAF AT THIS TIME. SOMETHING ELSE TO MONITOR FOR WEDNESDAY EVENING IS THE POTENTIAL FOR DRIZZLE OR FREEZING DRIZZLE IF TEMPERATURES ARE COLD ENOUGH...WITH CONFIDENCE LOW ON THE EXACT TEMPERATURE TREND DURING THIS PERIOD. RODRIGUEZ //ORD AND MDW CONFIDENCE...UPDATED 00Z... * HIGH CONFIDENCE WITH VFR CONDITIONS TONIGHT. * HIGH CONFIDENCE WITH WIND SPEED/DIRECTION. * MEDIUM HIGH CONFIDENCE WITH MVFR CONDITIONS LATE IN THE PERIOD. * LOW CONFIDENCE WITH IFR CONDITIONS AND FREEZING DRIZZLE LATE IN THE PERIOD. RODRIGUEZ //OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z... THURSDAY...IFR/LIFR LIKELY. CHANCE OF -RA/DZ WITH AREAS OF FOG. FRIDAY...IFR LIKELY. CHANCE OF -RA/-SN. SATURDAY...IFR POSSIBLE. CHANCE OF WINTRY MIX DURING THE DAY...THEN SNOW AT NIGHT. SUNDAY...IFR POSSIBLE. SNOW LIKELY. MONDAY...MVFR CEILINGS POSSIBLE. RODRIGUEZ && .MARINE... 315 PM CST WILL LEAVE HEADLINES AS IS THIS EVENING FOR MARGINAL WESTERLY GALES ON SOUTHERN PART OF THE LAKE...BUT ALLOW EVENING SHIFT TO ASSESS AND POSSIBLY CANCEL EARLY. SMALL CRAFT ADVISORY FROM WINTHROP HARBOR TO GARY IS IN GOOD SHAPE. THEN CONCERN SHIFTS TO LIKELY SOUTH-SOUTHWEST GALES ON WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT COURTESY OF STRONG PRESSURE FALLS AND A TIGHT PRESSURE GRADIENT WITH LOW PRESSURE APPROACHING FROM THE WEST AND HIGH PRESSURE OVER THE OH VALLEY. HAVE HIGHEST CONFIDENCE IN GALES DEVELOPING ON THE SOUTH HALF WITH SOMEWHAT LESSER CONFIDENCE ON THE NORTH IN TERMS OF DURATION AND SEEING PREVAILING GALES...BUT FELT IT WAS PRUDENT TO ISSUE A GALE WATCH FOR THE ENTIRE OPEN LAKE FROM 21Z WEDS TO 10Z THURS. WILL LIKELY NEED A SCA FOR THE NEAR SHORE ZONES DURING THIS TIME. AFTER GALE IS DROPPED FOR GARY TO MI CITY NSH ZONE THIS EVENING...ITS POSSIBLE THAT THE SCA MAY JUST BE EXTENDED THROUGH TOMORROW NIGHT FOR THIS ZONE. A COLD FRONT WILL THEN SHIFT SOUTH DOWN THE LAKE THURSDAY THROUGH THURSDAY NIGHT..WITH LARGE VARIANCE AMONGST FORECAST GUIDANCE IN THE TIMING OF THIS FRONT. HAVE FAVORED A SLOWER MOVEMENT OF THE FRONT DOWN THE SOUTHERN PORTION OF THE LAKE WITH THIS FORECAST ISSUANCE. THERE IS SOME POTENTIAL FOR FAIRLY STRONG BUT LIKELY SUB-GALE NORTHERLY WINDS BEHIND THE FRONT. WEAK HIGH PRESSURE WILL THEN RESULT IN LIGHTER WINDS FRIDAY NIGHT INTO SATURDAY. HOWEVER...ANOTHER STRONGER SYSTEM THEN LOOKS TO MOVE FROM THE OHIO VALLEY TOWARD THE CENTRAL LAKES LATE SATURDAY INTO SUNDAY. THE POTENTIAL CERTAINLY EXISTS FOR NORTHEAST TO NORTH GALES IN ASSOCIATION WITH THIS SYSTEM DEPENDING ON ITS ULTIMATE TRACK AND STRENGTH...BUT FOR NOW HAVE INCREASED WINDS TO 30 KT. RC && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 10 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL MIDNIGHT WEDNESDAY. GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...3 PM WEDNESDAY TO 4 AM THURSDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
  [top] Area Forecast Discussion National Weather Service Lincoln IL 817 PM CST Tue Dec 17 2013 .DISCUSSION... ISSUED 815 PM CST Tue Dec 17 2013 Surface high pressure over eastern Kansas and western Missouri early this evening will track to our south tonight. A very dry air mass was advecting southeast into central Illinois this evening with mid to upper teens common over the northern half of the forecast area. The dry air combined with just enough wind overnight should keep any significant fog problems at bay. Last few runs of the HRRR model have backed off with the low vsbys in parts of our area but with the ridge axis expected to be right over our area by 12z, not that confident to remove the current patchy fog wording in the grids late tonight. As the surface high shifts off to our southeast tomorrow, we can expect an increasing southerly wind across the entire area which should help push temperatures into the upper 30s north to the middle 40s southwest. Have made some minor adjustments to the evening dew points and temperatures, as well as backing off the fog wording until the 4am to 8am time frame. Updated zones should be out soon. Smith && .AVIATION... ISSUED 525 PM CST Tue Dec 17 2013 Main forecast concern revolves around fog potential in the 09z-13z time frame. Still expecting mainly VFR conditions this forecast period as surface high pressure settles to our south. West to northwest flow will bring in some very dry air at the surface with upstream dew points in the mid teens early this evening. However, with a mostly clear sky and diminishing winds along with a snow cover, there still is the potential for seeing some patchy fog late tonight. Confidence still not great enough at this point to include at any one site wtih all the short term models coming up with different solutions just before dawn. As the surface high shifts off to our southeast tomorrow, look for west winds tonight at around 10 kts or less, to back more into a southwest to south direction on Wednesday with speeds picking up to between 12 and 17 kts by afternoon. Smith && .PREV DISCUSSION... ISSUED 300 PM CST Tue Dec 17 2013 The short term will be highlighted by a warming trend through mid week. Fog may become an issue as the snow melts over the next few days. A cold front is still slated for Friday morning, with a major winter storm taking aim on the area for the weekend. Precip type issues remain the biggest challenge with that storm. The 12z guidance has generally trended warmer on Sat and Sat night, which means rain longer and farther north, with a band of freezing rain in our northern area. Snow chances may hold off until very late Sat night and possibly until Sunday as the colder air finally flows into central IL. Snow amounts on the NW side of this system could be very high, with the latest trends putting that band just to our northwest. Any shift in the placement of the stationary front and track of the low up along the front will be critical to precip type distribution and amounts of snow and ice. SHORT TERM...Tonight through Friday night. The quick clipper snows from today should be out of our southeast counties by evening. We will not mention any snow in the worded zones as a result. Fog potential tonight does not appear as high as previous model runs, although the models have not been handling the ground level moisture very well at all. We kept a mention of patchy fog in our grids for tonight, but do not expect any widespread dense fog despite very light winds and clear skies. Wednesday will see high pressure sliding east of IL and southerly winds increasing. Warm advection flows will intensify in the afternoon, helping to push temperatures into the 40s in many areas. Snow cover will reduce the effective heating of the sun, with energy going to melting the snow. That may keep highs in the upper 30s over areas with deeper snow. The additional ground level moisture should help fog develop Wed night, despite some steadier south winds overnight. Fog should linger Thursday morning as mid and upper level moisture increases ahead of the approaching cold front. Rain showers should hold off until afternoon when isentropic lift intensifies due to 45kts of flow up the 295k surface. Rain should generally remain north of Lincoln in proximity to the developing mid-level warm front and nose of the theta-e ridge. There remains some concern as to the extent of freezing rain later Thursday night into Friday morning as surface temps northwest of Peoria dip below freezing behind the cold front. We kept a mention of FZRA in that area, with a thin layer of icing possible. Precipitation chances should become confined mainly to the southeast half of our area Friday afternoon and Friday night as the cold front and shortwave shift east. Once again, any rain falling into the night could transition to freezing rain along and north of I-72. The cold front is projected to stall out just to the southeast of Illinois, in prep for a return push northward when the weekend storm approaches. LONG TERM...Saturday through Tuesday. A surge of warm air and moisture in the mid levels will strengthen on Saturday, pushing the front back north as a warm front. Rain will re-develop or advance northward during the day, with freezing rain possible in the morning north of I-72 before surface temps climb above freezing. All or our forecast area except maybe around Galesburg should climb above freezing during the afternoon, keeping all precipitation as rain. The timing and speed of the low riding up the front will dictate how soon that colder air will be drawn into the northern edges of the storm and change the rain to freezing rain and eventually snow. Saturday night could see an extended period of freezing rain in a band from SW to NE across our counties, including areas from Rushville/Jacksonville/ Springfield north to Canton/Peoria and east to Bloomington and Champaign. Ice amounts could reach over a quarter inch in some areas, depending on how soon the cold air arrives at low levels. Snow is expected to develop on the NW fringes of our area as soon as Saturday evening, but more likely after midnight into Sunday. A couple of inches of snow could accumulate on Sunday in areas west of I-57, with lesser amounts toward I-57 and east. A band of deformation snows could increase those amounts in bands west of I-55. There remains a great deal of uncertainty with the weekend storm system, but the trends have been for a warmer solution in our counties, even from the previously colder ECMWF. Dry and colder conditions will follow the storm, and should set up better travel conditions for Christmas Eve day through Christmas, and possibly longer. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1108 AM CST MON DEC 16 2013 .UPDATE... 1108 AM CST THE NEXT CLIPPER CONTINUES TO MAKE SOUTHEAST PROGRESS TOWARD THE AREA. LATEST RADAR MOSAIC SHOWS A BAND OF MODERATE TO HEAVY SNOW STRETCHING FROM NEAR RICE LAKE WISCONSIN SOUTH JUST EAST OF ROCHESTER MINNESOTA TO PRAIRIE DU CHIEN WISCONSIN WHICH IS TRACKING SOUTHEAST. A LOOK AT RECENT OBS FROM UP THIS WAY SHOW PERIODS OF 1/4SM VSBY WITH ROCHESTER COMING IN WITH ABOUT AN HOUR AND 20 MINUTES OF VSBY BELOW 1SM. BASED ON TRAJECTORY OF MOVEMENT THE CURRENT SOUTHERN EDGE OF THE HIGHEST REFLECTIVITY WOULD LIKELY TRACK JUST NORTH OF A LINE FROM ROCKFORD TO CHICAGO WITH PERIPHERAL LIGHTER INTENSITY SNOW EXTENDING FURTHER SOUTH ROUGHLY A STERLING TO RENSSELAER LINE. GOING POPS IN GOOD SHAPE COVERAGE WISE SO WILL ONLY MAKE MINOR TWEAKS AS WELL AS RAISE VALUES IN THE FAR NORTHEAST. TIMING STILL LOOKS ON TRACK TO AFFECT RFD EARLY THIS AFTERNOON AND THE CHICAGO METRO LATE THIS AFTERNOON...WITH THE PEAK PERIOD IN THE 3 OR 4 TO ABOUT 6 PM TIME FRAME. NEAR TERM FORECAST GUIDANCE SHOWS A RANGE OF SNOW FALL AMOUNTS AND HAVE VERY FEW RECENT REPORTS. AREAS A BIT FURTHER UPSTREAM ACROSS FAR SOUTHERN MINNESOTA DID SHOW AMOUNTS OF 1 TO 1.5 INCHES WHICH SEEMS REASONABLE AND FALLS IN LINE WITH THE CURRENT FORECAST OF 1 TO POSSIBLY 2 INCHES ALONG AND NORTH OF THE ROCKFORD TO CHICAGO TO VALPARAISO LINE WITH A QUICK DROP OFF TO THE SOUTH. THE MAIN ISSUE MAY BE A NARROWER BAND OF HIGHER INTENSITY SNOW THAN WHAT IS CURRENTLY OBSERVED UPSTREAM...LEADING TO A SHORTER DURATION WHICH WOULD THEN ALLOW FOR AMOUNTS OF LESS THAN AN INCH IN THE NORTHERN AREAS BUT THIS WILL BE MORE OF A NOWCAST DETERMINATION SO WILL STICK WITH THE 1-2 RANGE WITH HIGHEST AMOUNTS NORTH WITH RATES OF 0.5 TO 0.75 INCHES PER HOUR POSSIBLE. MDB //PREV DISCUSSION... 316 AM CST TODAY... MAIN CONCERNS FOR TODAY WILL BE ON THE APPROACH OF A CLIPPER SYSTEM THAT IS CURRENTLY PROGRESSING SOUTHEAST ACROSS THE NORTHERN PLAINS. IR IMAGERY EARLY THIS MORNING INDICATES A WEAK WAVE OVER CENTRAL/NORTHERN IL PUSHING EAST INTO NORTHCENTRAL IN. REGIONAL RADAR AND SFC OBS DEPICT SOME LIGHT SNOW FALLING FROM THIS WAVE...WITH A HANDFUL OF REPORTING SITES INDICATING REDUCED VSBYS TO ARND 1SM...INDICATING SOME LIGHT ACCUMS ARE LIKELY TAKING PLACE. THE BULK OF THE SNOW EARLY THIS MORNING HAS FALLEN SOUTH OF A ROCKFORD TO OHARE LINE...WITH AN EVEN GREATER FOCUS FROM LASALLE TO EASTERN WILL COUNTY AND POINTS SOUTH. EXPECT MOST LOCATIONS THAT HAVE SEEN LGT SNOW TO PICK UP BETWEEN A FEW TENTHS UP TO AND ARND 1" BEFORE ENDING ARND DAYBREAK. BASED ON IR IMAGERY THE CLEARING LINE WAS ALREADY PUSHING INTO FAR NORTHWEST IL...AND WILL CONTINUE TO BRING AN END TO THE MORNING SNOW. TEMPS BRIEFLY WARMED WITH THIS WAVE...HOWEVER WITH THE CLEARING EXPECTED TO PUSH OVER THESE AREAS WITHIN THE NEXT COUPLE OF HOURS TEMPS WILL QUICKLY RADIATE INTO THE SINGLE DIGITS AND POSSIBLY A HANDFUL OF POINTS ACROSS THE FAR WESTERN CWFA MAY DIP TO BELOW ZERO. AS PREVIOUSLY NOTED...YET ANOTHER MID-LVL WAVE IS PROGGED TO TAKE THE EXPRESS TRAIN FROM THE NORTHERN PLAINS TOWARDS SOUTHEAST WISC/NORTHEAST IL. ESTIMATED TIME OF ARRIVAL APPEARS TO BE BY MIDDAY...QUICKLY SHIFTING EAST BY MID-AFTERNOON. THE AREAS OF GREATEST CONCERN ARE NORTH OF A OGLE COUNTY TO KANKAKEE COUNTY LINE...WITH THE HIGHEST TOTALS FALLING ALONG AND NORTH OF A ROCKFORD TO CHICAGO LINE. UNFORTUNATELY IT SETS THE STAGE FOR A ROUGH COMMUTE HOME. GUIDANCE HAS BEEN UNDERDOING THIS WAVE WITH RESPECT TO THE WEAK ADVECTION AHEAD...IRONICALLY THE GFS HAS HAD A SLIGHTLY BETTER HANDLE. LOOKING AT BUFR PROFILES VIA THE GFS AND A LITTLE WEDGE OF 3HOURS BETWEEN 20-23Z INDICATES IMPRESSIVE OMEGA (LIFT) INTO THE FAVORED DGZ. DESPITE THE DGZ NOT BEING VERY THICK...THE EFFICIENCY OF THIS WAVE WILL LIKELY PRODUCE A BURST OF MODERATE TO HEAVY SNOW IN THIS TIMEFRAME. COBB OUTPUT USING THE GFS INDICATES HOURLY SNOWFALL RATES OF 1"/HR WITH A RATIO IN THE UPPER TEENS. THIS APPEARS TO PUT DOWN A QUICK 1-2" OF SNOWFALL THIS AFTN...AND IF THE SYSTEM SLOWS...THIS COULD EASILY BECOME 2-3" MAINLY ALONG AND NORTH OF A ROCKFORD TO CHICAGO LINE. AS FOR TEMPS TODAY...CONSIDERABLE CLOUD COVER WILL KEEP TEMPS IN CHECK AND LIKELY TOP OUT IN THE UPR TEENS TO LOW 20S. THE FAR SOUTHERN CWFA COULD WARM INTO THE MID 20S BY MID/LATE AFTN. CONFIDENCE IN TEMPS/SNOW...HIGH. CONFIDENCE IN SNOWFALL TOTALS...HIGH. TONIGHT... ON THE HEELS OF THE AFTN MID-LVL CLIPPER PRODUCING SNOW FOR PORTIONS OF THE CWFA...IT APPEARS MOTHER NATURE HAS INDEED FOLLOWED SUIT WITH THE GIFT THAT KEEPS ON GIVING...AS YET ANOTHER MID-LVL WAVE IS POISED TO ARRIVE ACROSS THE UPPER MIDWEST AND INTO THE CWFA LATE TONIGHT THRU DAYBREAK TUE. MID-LVL VORT WILL REMAIN OVERHEAD WITH TEMPS ALOFT HOLDING IN THE -6 TO -9 DEG C RANGE. DESPITE CONSIDERABLE CLOUD COVER TONIGHT...TEMPS SHUD BE ABLE TO RADIATE INTO THE LOW/MID TEENS. THE OVERNIGHT CLIPPER DOES NOT APPEAR TO BE AS POTENT AS ITS PREDECESSOR...NONETHELESS IT WILL NOT TAKE MUCH MOISTURE TO EASILY PRODUCE ANOTHER HALF INCH OF SNOWFALL OVERNIGHT INTO DAYBREAK TUE. CONFIDENCE IN TEMPS/SNOW...HIGH. TUESDAY THROUGH WEDNESDAY... MAIN FEATURE FOR TUE WILL BE THE EVOLVING WEATHER PATTERN...WHICH WILL BE UNDERGOING SOME CHANGES. THE CHALLENGE WILL BE ON HOW WARM SFC TEMPS WILL BE...GIVEN THE EXPANSIVE SNOWPACK. ENSEMBLES INDICATE THE ANOMALOUS RIDGES...ONE ACROSS THE CENTRAL ATLANTIC AND THE OTHER ACROSS THE EASTERN PACIFIC...WILL BE ON THE MOVE BY TUE. THIS HAS RECENTLY CREATED A BOTTLENECK WITH THE 500MB TROUGH PARKED ACROSS THE GREAT LAKES/ONTARIO...BUT WILL BEGIN TO WEAKEN AND PIVOT EAST THROUGH THE MIDDLE OF THE WEEK. BY WED GUIDANCE INDICATES THE MID-LVL FLOW WILL FLATTEN OUT...WHICH ONLY APPEARS TO BE MORE OF A TRANSITIONAL PHASE AS YET ANOTHER HIGH AMPLITUDE RIDGE IS POISED TO DEVELOP ACROSS THE EASTERN PACIFIC. SFC RIDGING WILL ENGULF MUCH OF THE SOUTHERN STATES...AND LIKELY STRETCH NORTH INTO THE CWFA BY TUE AFTN THRU WED. BRINGING A PERIOD OF DRY WEATHER THRU WED EVE. THE LARGEST CHALLENGE FOR TUE/WED WILL BE ON HOW WARM TEMPS WILL ACTUALLY BECOME. AS PREVIOUSLY NOTED ABOUT THE EXPANSIVE SNOWPACK...GUIDANCE HAS CONTINUED TO STRUGGLE WITH THE SIZE AND DEPTH OF SNOWPACK...WHICH MOST LIKELY IS CAUSING TEMPS TO BE MODERATING A LITTLE TOO MUCH FOR WED. FLOW DOES TURN SOUTHWESTERLY WITH WARMER AIR ADVECTING INTO THE REGION...HOWEVER IT WILL LIKELY BECOME SOMEWHAT TEMPERED BY THE SNOWPACK. SO A DECENT THERMAL INVERSION WILL PROB SETUP WED AFTN/EVE. WITH THE WARMER SLOWLY LIFTING OVERHEAD...COUPLED WITH RISING DEW POINTS...THE SNOWPACK WILL BEGIN TO MELT. THUS LEADING TO THE DEVELOPMENT OF PATCHY FOG. AT THIS TIME HAVE COOLED TEMPS A DEG OR TWO FOR WED...SIDING MORE WITH THE LATEST GFS...WHICH KEEPS TEMPS MAINLY ARND 30. THEN OVERNIGHT LOWS WILL LIKELY ONLY FALL A FEW DEGREES INTO THE MID/UPR 20S. CONFIDENCE IN TEMPS...MEDIUM. THURSDAY THROUGH SATURDAY... THE SEMI-ZONAL FLOW THAT SETUP FOR WED WILL EVOLVE INTO A SOUTHWESTERLY FLOW WITH WEAK RIDGING DEVELOPING ACROSS THE EASTERN CONUS. GUIDANCE HAS CONTINUED IN THE MEDIUM TERM TO PROG A 500MB VORT MAX SLIDING EAST INTO THE FAR SOUTHWESTERN CONUS THUR. TIMING HAS SLOWED SLIGHTLY...HOWEVER THE ENERGY ASSOCIATED WITH THIS SYSTEM WILL LIKELY SPAWN A SFC WAVE SOMEWHERE ALONG THE LEE-SIDE OF THE ROCKIES NEAR THE OKLAHOMA PAN-HANDLE. THE EC/GFS DIFFER ON THE PATH OF THIS WAVE BEYOND THUR. THIS WILL LIKELY REMAIN A CHALLENGE AS NUMERICAL WEATHER MODELS FREQUENTLY STRUGGLE ON THE PLACEMENT OF BARE GROUND/SNOWPACK...RESULTING IN A SOMEWHAT WOBBLE EFFECT ON THE PATH A SFC LOW WILL TAKE. AT THIS TIME IT APPEARS FAVORABLE THAT THE LOW WILL LIFT NORTHEAST ACROSS THE CENTRAL PLAINS TOWARDS THE CWFA FRI MORNING. WITH THE ABUNDANCE OF WARM AIR ADVECTION ACROSS THE REGION THUR-FRI...PRECIP WILL LIKELY CHANGE OVER FROM A RAIN/SNOW MIX AT ONSET TO RAIN. PATCHY FOG WILL ALSO ACCOMPANY THE PRECIP FROM THE MELTING SNOWPACK. MAX TEMPS FOR THUR/FRI WILL CONTINUE TO BE A CHALLENGE GIVEN THE AFOREMENTIONED CONDITIONS...SO HAVE SIDED MORE WITH PREVIOUS FORECASTS AND KEEPING TEMPS IN THE MID/UPR 30S. ALTHOUGH THIS WILL ALSO HINGE ON THE TRACK OF THE SFC LOW...WHICH ANY ADJUSTMENTS TO THE SOUTHEAST WOULD FAVORED COOLER TEMPS AND MAY INTRODUCE ADDITIONAL P-TYPE CONCERNS. THEN ENSEMBLES CONTINUE TO POINT TOWARDS A RETURN OF TROUGHING FOR THE UPPER MIDWEST/GREAT LAKES REGION TOWARDS THE END OF THE WEEK. A COLD FRONT SHUD PUSH ACROSS THE CWFA FRI...BRINGING TEMPS BACK TO SEASONAL CONDS. SAT WILL FEATURE TEMPS HOLDING IN THE UPR 20S/ARND 30. ACROSS THE WESTERN CONUS THE 500MB TROUGH WILL PIVOT EAST SAT...AND GUIDANCE CONTINUES TO INDICATE A POTENT SYSTEM EJECTING EAST AND LIFTING NORTHEAST ACROSS THE TENN/OHIO VALLEY FOR THE WEEKEND. CONFIDENCE...MEDIUM. SUNDAY THROUGH FIRST HALF OF CHRISTMAS WEEK... FOR THE SECOND HALF OF THE WEEKEND INTO EARLY CHRISTMAS WEEK...ENSEMBLES CONTINUE TO POINT AT A RETURN TO COOL WEATHER FOR THE REGION. THE EASTERN PACIFIC/WESTERN ATLANTIC MID-LVL RIDGES RETURN...ALTHOUGH DO NOT APPEAR TO BE AS STRONG. THIS ALLOWS SOME TROUGHING ACROSS THE GREAT LAKES...WITH PERHAPS A SERIES OF WEAK WAVES AND SOME LGT SNOW FOR THE END OF THE WEEKEND/EARLY CHRISTMAS WEEK. CONFIDENCE...MEDIUM. BEACHLER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * SNOW THIS AFTERNOON AFTER 21Z. A PERIOD OF VIS UNDER A MILE POSSIBLE IN THE HEAVIER BANDS OF SNOW...BETWEEN 22 AND 00 UTC. * CIGS MAY FALL TO IFR FOR A PERIOD IN THE AFTN DURING THE SNOW. * CIGS REMAIN MVFR OVERNIGHT WITH SNOW ENDING IN THE EVENING. * ANOTHER ROUND OF SNOW EXPECTED BETWEEN 12 AND 16 UTC...WITH LOW VIS DOWN AROUND 1SM LIKELY. * STRONG NORTHWESTERLY WINDS ON DEVELOPING AFTER 16 UTC ON TUESDAY. KJB //DISCUSSION...UPDATED 18Z... THERE WILL BE A FAIRLY ACTIVE PERIOD OF WEATHER ACROSS THE TERMINALS THROUGH THE PERIOD...AS TWO CLIPPER SYSTEMS IMPACT THE AREA. THE FIRST DISTURBANCE...CURRENTLY DROPPING SOUTHEASTWARD ACROSS WISCONSIN AND NORTHERN IOWA...IS SUPPORTING A BAND OF MODERATE TO OCCASIONALLY HEAVY SNOW ACROSS SOUTHEASTERN MN AND ADJACENT AREAS OF WI AND IA EARLY THIS AFTERNOON. THIS ACTIVITY SHOULD MOVE ACROSS NORTHERN ILLINOIS BY MID TO LATE AFTERNOON...LIKELY PRODUCING A SHORT PERIOD OF MODERATE SNOW. SEVERAL SITES UNDER THIS BAND OF SNOW ARE DROPPING DOWN TO A QUARTER MILE. IT APPEARS SIMILAR CONDITIONS WILL BE OBSERVED AT MOST OF THE EASTERN TERMINALS AFTER 3 PM THIS AFTERNOON...WITH THE MOSTLY LIKELY TIME FOR LOW VIS UNDER A MILE BETWEEN 4 AND 6 PM...AND A HOUR OR TWO SOONER AT KRFD. ANY HEAVY SNOW BURSTS WOULD LIKELY ONLY LAST UP TO AN HOUR...WITH LIGHTER SNOW OUTSIDE OF THESE BANDS. CIGS WITHIN THE SNOW WILL ALSO LIKELY FALL DOWN AROUND OR POSSIBLY JUST BELOW 1,000 FEET AGL FOR BRIEF PERIODS. THE SNOW WILL ABATE QUICKLY AFTER 7 PM THIS EVENING. THE NEXT DISTURBANCE ARRIVES FOR EARLY TUESDAY MORNING. THIS SYSTEM WILL BE VERY SIMILAR TO THE FIRST...WITH ANOTHER DECENT 3 TO 4 HOUR WINDOW OF SOME MODERATE...TO PERHAPS HEAVY SNOWFALL. THE BEST TIMING FOR MOST TERMINAL SITES WOULD BE BETWEEN ABOUT 12 UTC AND 16 UTC TUESDAY MORNING. ONCE THE SNOW ENDS BY LATE MORNING...THE MAIN CONCERN WILL BE WITH THE WINDS. THE WINDS ARE EXPECTED TO INCREASE OUT OF THE NORTHWEST BY LATE MORNING. WIND GUSTS IN EXCESS OF 30 KT APPEAR LIKELY...AND THEY COULD EVEN BE CLOSE TO 35 KT FOR A SHORT PERIOD EARLY TUESDAY AFTERNOON. KJB //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH CONFIDENCE IN SNOW FALLING THIS AFTN AND RELATED VSBY AND CIG HEIGHTS. * MEDIUM-HIGH CONFIDENCE IN SN TUESDAY MORNING. * HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. KJB //OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z... TUESDAY NIGHT AND WEDNESDAY...VFR. THURSDAY...CHC OF RA AND SN IN THE MORNING BECOMING ALL RAIN. FOG IS LIKELY. IFR CIGS. FRIDAY...CHC RAIN OR SNOW BECOMING ALL SNOW BY THE AFTERNOON. IFR CIGS PSBL...IMPROVING OVERNIGHT. SATURDAY...CHC SNOW. MVFR OR LOWER. SUNDAY...SCHC SNOW IN THE MORNING. MVFR PSBL. JEE && .MARINE... 403 AM CST HIGH PRESSURE IS MOVING OVER THE LAKE THIS MORNING WITH WINDS BECOMING SOUTHWEST THROUGH THE MORNING. WAVES WILL CONTINUE TO SUBSIDE THEREFORE EXPECTING THE SMALL CRAFT ADVISORY FOR PLACES EAST OF GARY INDIANA TO END ON TIME THIS MORNING. LOW PRESSURE PASSES TO THE NORTH TOMORROW AND THE PRESSURE GRADIENT TIGHTENS RESULTING IN INCREASING WINDS THROUGH TUESDAY. ISSUED A GALE WATCH FOR THE SOUTHERN HALF OF THE LAKE AND POINTS EAST OF GARY FOR TUESDAY MORNING THROUGH TUESDAY EVENING. THE OPEN WATERS SEEM LIKE A SLAM DUNK...BUT CONFIDENCE IS MEDIUM FOR THE INDIANA NEARSHORE WATERS. REGARDLESS A WATCH IS CERTAINLY VALID. FOR THE ILLINOIS NEARSHORE WATERS...ISSUED ANOTHER SMALL CRAFT ADVISORY AS WINDS SHOULD TOP OUT AROUND 30 KT. COULD SEE A FEW GALE FORCE GUSTS TUESDAY MORNING...BUT NOT ENOUGH TO WARRANT A GALE HEADLINE. WINDS DIMINISH TUESDAY NIGHT BUT WAVES WILL REMAIN HAZARDOUS OVER NORTHWEST INDIANA...SO AN ADDITIONAL SMALL CRAFT ADVISORY WILL BE NEEDED. HIGH PRESSURE PASSES TO OUR SOUTH TUESDAY NIGHT INTO WEDNESDAY AND A LOW PRESSURE TROUGH APPROACHES FROM THE WEST WEDNESDAY. WINDS TURN SOUTHWEST AND INCREASE IN SPEED. A SMALL CRAFT ADVISORY MAY BE NEEDED FOR HIGH WINDS. THE NEXT LOW PRESSURE SYSTEM PASSES OVER THE LAKE THURSDAY NIGHT WITH WINDS BECOMING NORTHWEST ON ITS BACKSIDE. HIGH PRESSURE ARRIVES FRIDAY NIGHT WITH LIGHT WINDS EXPECTED AS WE MOVE INTO THE WEEKEND. YET ANOTHER LOW PRESSURE SYSTEM PUSHES UP THE OHIO RIVER VALLEY SATURDAY NIGHT INTO SUNDAY WITH WINDS STRENGTHENING AND BECOMING NORTHWEST. JEE && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...LMZ744-LMZ745...MIDNIGHT TUESDAY TO 9 AM TUESDAY. GALE WATCH...LMZ744-LMZ745...9 AM TUESDAY TO 9 PM TUESDAY. SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...MIDNIGHT TUESDAY TO MIDNIGHT WEDNESDAY. GALE WATCH...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...5 AM TUESDAY TO 9 PM TUESDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 1150 AM CST Mon Dec 16 2013 .DISCUSSION... ISSUED 1000 AM CST Mon Dec 16 2013 Clouds currently blanket most of central Illinois in the wake of a weak clipper system that tracked through the region overnight. Trailing frontal boundary stretches from southern Illinois northwestward into the Dakotas. Immediately north of the boundary, low clouds and fog persist from near Terre Haute, Indiana westward to Quincy. With winds expected to remain very light from the east/northeast until later this afternoon when the front begins to lift back northward, think clouds will hold firm across the area. The exception will be across the far southern KILX CWA around Flora and Lawrenceville where partly to mostly sunny skies will be observed. Meanwhile, next clipper system is currently evident on water vapor imagery over northern Minnesota. This system is bringing light snow to much of Minnesota into northern Iowa, with its projected trajectory to remain mostly north of central Illinois today. 12z NAM forecast soundings remain quite dry and latest HRRR keeps radar echoes further north. Will therefore only mention a chance for flurries along/north of I-74 this afternoon/evening. Zone update has already been issued. Barnes && .AVIATION... ISSUED 1150 AM CST Mon Dec 16 2013 IFR conditions will continue at the I-72 terminals this afternoon as a stationary frontal boundary remains in the vicinity. Once weak low pressure tracks into the Great Lakes, light/variable winds initially will become westerly by early evening. This will allow ceilings to improve markedly into the VFR category. Based on timing of clipper system to the north, winds will switch to westerly at KPIA by 00z then further east at KCMI by 03z. After that, W/NW winds will prevail through Tuesday morning with gradually clearing skies. Barnes && .PREV DISCUSSION... ISSUED 256 AM CST Mon Dec 16 2013 Weak high pressure over much of the Midwest with northwesterly flow aloft ushering in a couple of clipper systems in the short term. Snow coming to an end this morning over ILX, but first issues with the forecast revolve around the resolution of the next system moving in later this afternoon/evening. Ridge building in the SW will eventually result in some moderation of the temperatures in the region, but existing snow field will counter the warm up as well. Influence of the snowpack not represented well in the models. In addition, GFS and ECMWF starting to come more into line with the next major system next weekend. However, the details are the fine line with major ramifications to the thermal profile and resultant precip type. SHORT TERM...Today and Tomorrow... Cold and cloudy conditions continue as one clipper pulls away from the region and another comes in on its heels later this afternoon. Snow showers should remain mainly to the NE, but considering the more southerly track of this mornings wave, will keep slight chance pops in the NE. Little to no accumulations expected and will keep the QPF low. Temperatures a little under guidance today as the impact of the snow is not showing up enough in the models. Another cold overnight, and temperatures begin to moderate with more westerly flow at the sfc for Tuesday. Still concerned that the forecast is a couple degrees too high, particularly in the south. Winds becoming more southwesterly for Tuesday night, especially after midnight, ushering in warmer air with a bit more moisture. Moving this RH over a snowpack brings the threat of fog. However, between the winds staying up just a bit and with the models having a major issue with the boundary layer, confidence is low. LONG TERM...Wednesday through Sunday... Low confidence continues with the temperatures through the middle of the week. Will depend greatly on the persistence of the WAA from the SW and the snow melt. After the main trof pulls to the east Tues night/Wed, flow eventually moves to a more SWrly pattern with a trof digging in over the west coast. Deep upper low becoming briefly cut off in the GFS and ECMWF as the models start to converge. SWrly flow setting up and putting ILX in a transition zone temperature wise with the initial passage of the front on Thurs night/Friday. Front moving into and stalling out just to the south over the Ohio River Valley. Location of the boundary as a series of upper waves eject out and along said front will make a major difference on the forecast. Northerly extent of the precip with respect to the front is the main issue for the forecast as well as how deep into the cold air the precip reaches. Latest ECMWF even pointing to ice, while GFS maintains mostly snow after a transitional mix. Precip type is still ambiguous, much less QPF depending on extent of precip with the front stalled to the south. A series of small waves rippling along the stalled front keeps high chance pops in the AllBlend for Fri through Sunday and will leave that as is. HJS && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
920 PM EST TUE DEC 17 2013 .UPDATE... THE NEAR TERM SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 326 PM EST TUE DEC 17 2013 HIGH PRESSURE WILL BRING A BRIEF BREAK FROM PRECIPITATION TO THE AREA TONIGHT THROUGH WEDNESDAY NIGHT. ON THURSDAY THIS WILL SHIFT TO THE SOUTHEAST PUTTING CENTRAL INDIANA IN A SOUTHWEST FLOW PATTERN WHICH WILL BRING WARMER TEMPERATURES AND RAIN TO THE AREA. ON SUNDAY THIS COULD CHANGE OVER TO SNOW OR A MIX AS COLD AIR FILTERS IN AFTER A COLD FRONTAL PASSAGE. DRIER AIR WILL MOVE IN BEHIND THAT SYSTEM FOR A DRY START TO THE WORK WEEK. && .NEAR TERM /REST OF TONIGHT/... ISSUED AT 920 PM EST TUE DEC 17 2013 SOME RESIDUAL LOW CLOUDS LINGERING OVER THE AREA...BUT THESE EXPECTED TO GRADUALLY MOVE OFF TO THE EAST OVER THE NEXT SEVERAL HOURS AS DRIER AIR ADVECTS IN. LOW CLOUDS OVER NORTHERN ILLINOIS MAY GRAZE THE FAR NORTHERN ZONES LATER TONIGHT BASED ON SHORT TERM MODEL DATA...BUT OVERALL EXPECTED TREND IS FOR SKIES TO CLEAR. CURRENT TEMPERATURES WARMER THAN WHAT WAS EXPECTED BY THIS TIME...BUT WITH DIMINISHING WINDS AND CLEARING SKIES...THINK TEMPERATURES WILL START TAILING OFF MORE LATER TONIGHT. LOW LEVEL THICKNESSES SUPPORT THE CURRENT FORECAST LOWS...SO WILL NOT CHANGE THEM AT THIS TIME. ONLY CHANGE TO FORECAST ON THE UPDATE IS TO TAKE OUT THE WIND GUSTS. PREVIOUS DISCUSSION FOLLOWS. UPPER RIDGING WILL START TO BUILD OVER THE AREA TONIGHT FINALLY BRINGING AN END TO CHANCES FOR SNOW AND FLURRIES. SKY COVER SHOULD START TO SCATTER OUT FROM THE NORTHWEST TO SOUTHEAST. WITH THIS IN MIND STUCK CLOSER TO THE LOWER END OF GUIDANCE NUMBERS FOR LOWS IN THE MIDDLE TEENS NORTH TO AROUND 20 SOUTH. FORECAST SOUNDINGS NO LONGER LOOK AS STEEP WITH THE INVERSION AND GUIDANCE SHOWS NO INDICATIONS OF FOG OVERNIGHT. LOOKING UPSTREAM VISIBILITIES INCREASE GREATLY WITH THE INCREASED MIXING BEHIND THE UPPER WAVE...SO DECIDED TO REMOVE THE PATCHY FOG MENTION. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... ISSUED AT 326 PM EST TUE DEC 17 2013 HIGH PRESSURE WILL SLIDE THROUGH TO THE SOUTH OF THE AREA WEDNESDAY AND WEDNESDAY NIGHT. ALONG WITH UPPER RIDGING THIS SHOULD ALLOW FOR MOSTLY CLEAR TO PARTLY CLOUDY SKIES AND INCREASING TEMPERATURES AS WARM ADVECTION RAMPS UP. HAVE SOME CONCERNS THAT THIS WARM ADVECTION OVER WHATEVER SNOWPACK IS LEFT COULD LEAD TO SOME ADVECTION FOG LATE WEDNESDAY NIGHT. NOT CERTAIN MUCH SNOW WILL BE LEFT THOUGH AND WINDS MIGHT BE A LITTLE TOO STRONG FOR SUCH A SET UP THOUGH SO UNCERTAINTY IS PRETTY HIGH. WITH THIS IN MIND WILL ADD PATCHY FOG BUT NOTHING WORSE THAN THAT. ON THURSDAY SHOULD SEE INCREASING CLOUDS WITH THE WARM ADVECTION. THURSDAY NIGHT GOOD LOW LEVEL JET SETS UP AND SHOULD PROVIDE PLENTY OF FORCING FOR RAIN...AND THUS STUCK WITH HIGHER GUIDANCE NUMBERS FOR LIKELY POPS. FRIDAY THE COLD FRONT MOVES THROUGH THE AREA BUT STALLS OUT TO THE SOUTH AND NO REAL COLD ADVECTION GETS STARTED UNTIL LATER IN THE LONG TERM. THE FORCING FROM THE FRONT THOUGH SHOULD KEEP RAIN LIKELY ACROSS THE AREA THROUGH THE DAY. TEMPERATURE-WISE STUCK WITH WARMER GUIDANCE NUMBERS UNDER STRONG SOUTHWEST FLOW. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ISSUED AT 147 PM EST TUE DEC 17 2013 GFS AND ECMWF ARE COMING INTO BETTER AGREEMENT THAT A WET AND ACTIVE PATTERN WILL BE IN PLACE DURING THE WEEKEND. A FRONTAL BOUNDARY LOOKS TO BE IN PLACE ACROSS INDIANA ON FRIDAY NIGHT INTO SATURDAY. A TROUGH ALOFT IS EXPECTED TO PUSH THROUGH THE AREA...PROVIDING LIFT. WITH GOOD MOISTURE IN PLACE AHEAD OF THESE DYNAMICS...CONFIDENCE IN A RAIN FORECAST IS BECOMING HIGHER. ECMWF AND GFS DISAGREE WITH FRONTAL PASSAGE WITH THE ECMWF APPEARING TO BE A BIT SLOW. FOR NOW WILL NOR TRY ANY TIME ANY KIND OF PRECIPITATION CHANGE OVER...BUT JUST MENTION CHANCES FOR RAIN AND/OR SNOW. AS THE FRONT AND UPPER TROUGH DEPART ON SUNDAY NIGHT INTO MONDAY...A HIGH PRESSURE SYSTEM OF COLD...POLAR AIR WILL SETTLE ACROSS THE OHIO VALLEY...RESULTING IN DRY WEATHER WITH TEMPERATURES SLIGHTLY BELOW NORMAL. && .AVIATION /DISCUSSION FOR 180300Z TAF ISSUANCE/... ISSUED AT 912 PM EST TUE DEC 17 2013 INITIAL AREA OF STRATUS HAS LARGELY SHIFTED EAST OF THE TERMINALS AS OF 02Z. A SECOND AREA OF STRATUS WITH CEILINGS AT 3500-4000FT IS DROPPING SOUTHEAST FROM NORTHERN ILLINOIS. MODEL SOUNDINGS AND RH PROGS FROM THE NAM AND RAP BOTH INDICATE THAT OTHER THAN KLAF...THIS AREA OF CLOUDS SHOULD REMAIN NORTH OF THE OTHER TERMINALS. 00Z DISCUSSION FOLLOWS. MVFR CONDITIONS ARE POSSIBLE THIS EVENING...THEN VFR CONDITIONS EXPECTED THROUGH WEDNESDAY. QUICK MOVING UPPER WAVE THAT BROUGHT THE SNOW SHOWERS DURING THE AFTERNOON HAVE RAPIDLY MOVED INTO OHIO THIS EVENING. STUBBORN STRATOCU DECK LINGERING AT ALL SITES EARLY THIS EVENING AIDED BY LINGERING LOW LEVEL MOISTURE. DRIER AIR PRESENT OVER THE MID MISSISSIPPI VALLEY IN CONCERT WITH HIGH PRESSURE...AND THIS SHOULD FINALLY PUSH THE MVFR DECK EAST OF ALL TERMINALS BY MID/LATE EVENING. SKIES SHOULD BECOME MOSTLY CLEAR OVERNIGHT WITH W/NW WINDS AT 5-10KTS PRECLUDING WIDESPREAD VISIBILITY RESTRICTIONS. THE HIGH WILL DRIFT INTO THE SOUTHEAST STATES BY WEDNESDAY EVENING...WITH WESTERLY WINDS GRADUALLY BACKING TO A SOUTHERLY DIRECTION BY LATE DAY AND STRENGTHENING TO NEAR 15KTS BY THE AFTERNOON AS THE SURFACE PRESSURE GRADIENT TIGHTENS. OTHER THAN PASSING MID AND HIGH LEVEL CLOUDS...ANTICIPATE MOSTLY SUNNY SKIES THROUGHOUT THE DAY. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...CP NEAR TERM...CP/JAS SHORT TERM...CP LONG TERM....PUMA AVIATION...RYAN VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
912 PM EST TUE DEC 17 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 326 PM EST TUE DEC 17 2013 HIGH PRESSURE WILL BRING A BRIEF BREAK FROM PRECIPITATION TO THE AREA TONIGHT THROUGH WEDNESDAY NIGHT. ON THURSDAY THIS WILL SHIFT TO THE SOUTHEAST PUTTING CENTRAL INDIANA IN A SOUTHWEST FLOW PATTERN WHICH WILL BRING WARMER TEMPERATURES AND RAIN TO THE AREA. ON SUNDAY THIS COULD CHANGE OVER TO SNOW OR A MIX AS COLD AIR FILTERS IN AFTER A COLD FRONTAL PASSAGE. DRIER AIR WILL MOVE IN BEHIND THAT SYSTEM FOR A DRY START TO THE WORK WEEK. && .NEAR TERM /TONIGHT/... ISSUED AT 326 PM EST TUE DEC 17 2013 UPPER RIDGING WILL START TO BUILD OVER THE AREA TONIGHT FINALLY BRINGING AN END TO CHANCES FOR SNOW AND FLURRIES. SKY COVER SHOULD START TO SCATTER OUT FROM THE NORTHWEST TO SOUTHEAST. WITH THIS IN MIND STUCK CLOSER TO THE LOWER END OF GUIDANCE NUMBERS FOR LOWS IN THE MIDDLE TEENS NORTH TO AROUND 20 SOUTH. FORECAST SOUNDINGS NO LONGER LOOK AS STEEP WITH THE INVERSION AND GUIDANCE SHOWS NO INDICATIONS OF FOG OVERNIGHT. LOOKING UPSTREAM VISIBILITIES INCREASE GREATLY WITH THE INCREASED MIXING BEHIND THE UPPER WAVE...SO DECIDED TO REMOVE THE PATCHY FOG MENTION. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... ISSUED AT 326 PM EST TUE DEC 17 2013 HIGH PRESSURE WILL SLIDE THROUGH TO THE SOUTH OF THE AREA WEDNESDAY AND WEDNESDAY NIGHT. ALONG WITH UPPER RIDGING THIS SHOULD ALLOW FOR MOSTLY CLEAR TO PARTLY CLOUDY SKIES AND INCREASING TEMPERATURES AS WARM ADVECTION RAMPS UP. HAVE SOME CONCERNS THAT THIS WARM ADVECTION OVER WHATEVER SNOWPACK IS LEFT COULD LEAD TO SOME ADVECTION FOG LATE WEDNESDAY NIGHT. NOT CERTAIN MUCH SNOW WILL BE LEFT THOUGH AND WINDS MIGHT BE A LITTLE TOO STRONG FOR SUCH A SET UP THOUGH SO UNCERTAINTY IS PRETTY HIGH. WITH THIS IN MIND WILL ADD PATCHY FOG BUT NOTHING WORSE THAN THAT. ON THURSDAY SHOULD SEE INCREASING CLOUDS WITH THE WARM ADVECTION. THURSDAY NIGHT GOOD LOW LEVEL JET SETS UP AND SHOULD PROVIDE PLENTY OF FORCING FOR RAIN...AND THUS STUCK WITH HIGHER GUIDANCE NUMBERS FOR LIKELY POPS. FRIDAY THE COLD FRONT MOVES THROUGH THE AREA BUT STALLS OUT TO THE SOUTH AND NO REAL COLD ADVECTION GETS STARTED UNTIL LATER IN THE LONG TERM. THE FORCING FROM THE FRONT THOUGH SHOULD KEEP RAIN LIKELY ACROSS THE AREA THROUGH THE DAY. TEMPERATURE-WISE STUCK WITH WARMER GUIDANCE NUMBERS UNDER STRONG SOUTHWEST FLOW. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ISSUED AT 147 PM EST TUE DEC 17 2013 GFS AND ECMWF ARE COMING INTO BETTER AGREEMENT THAT A WET AND ACTIVE PATTERN WILL BE IN PLACE DURING THE WEEKEND. A FRONTAL BOUNDARY LOOKS TO BE IN PLACE ACROSS INDIANA ON FRIDAY NIGHT INTO SATURDAY. A TROUGH ALOFT IS EXPECTED TO PUSH THROUGH THE AREA...PROVIDING LIFT. WITH GOOD MOISTURE IN PLACE AHEAD OF THESE DYNAMICS...CONFIDENCE IN A RAIN FORECAST IS BECOMING HIGHER. ECMWF AND GFS DISAGREE WITH FRONTAL PASSAGE WITH THE ECMWF APPEARING TO BE A BIT SLOW. FOR NOW WILL NOR TRY ANY TIME ANY KIND OF PRECIPITATION CHANGE OVER...BUT JUST MENTION CHANCES FOR RAIN AND/OR SNOW. AS THE FRONT AND UPPER TROUGH DEPART ON SUNDAY NIGHT INTO MONDAY...A HIGH PRESSURE SYSTEM OF COLD...POLAR AIR WILL SETTLE ACROSS THE OHIO VALLEY...RESULTING IN DRY WEATHER WITH TEMPERATURES SLIGHTLY BELOW NORMAL. && .AVIATION /DISCUSSION FOR 180300Z TAF ISSUANCE/... ISSUED AT 912 PM EST TUE DEC 17 2013 INITIAL AREA OF STRATUS HAS LARGELY SHIFTED EAST OF THE TERMINALS AS OF 02Z. A SECOND AREA OF STRATUS WITH CEILINGS AT 3500-4000FT IS DROPPING SOUTHEAST FROM NORTHERN ILLINOIS. MODEL SOUNDINGS AND RH PROGS FROM THE NAM AND RAP BOTH INDICATE THAT OTHER THAN KLAF...THIS AREA OF CLOUDS SHOULD REMAIN NORTH OF THE OTHER TERMINALS. 00Z DISCUSSION FOLLOWS. MVFR CONDITIONS ARE POSSIBLE THIS EVENING...THEN VFR CONDITIONS EXPECTED THROUGH WEDNESDAY. QUICK MOVING UPPER WAVE THAT BROUGHT THE SNOW SHOWERS DURING THE AFTERNOON HAVE RAPIDLY MOVED INTO OHIO THIS EVENING. STUBBORN STRATOCU DECK LINGERING AT ALL SITES EARLY THIS EVENING AIDED BY LINGERING LOW LEVEL MOISTURE. DRIER AIR PRESENT OVER THE MID MISSISSIPPI VALLEY IN CONCERT WITH HIGH PRESSURE...AND THIS SHOULD FINALLY PUSH THE MVFR DECK EAST OF ALL TERMINALS BY MID/LATE EVENING. SKIES SHOULD BECOME MOSTLY CLEAR OVERNIGHT WITH W/NW WINDS AT 5-10KTS PRECLUDING WIDESPREAD VISIBILITY RESTRICTIONS. THE HIGH WILL DRIFT INTO THE SOUTHEAST STATES BY WEDNESDAY EVENING...WITH WESTERLY WINDS GRADUALLY BACKING TO A SOUTHERLY DIRECTION BY LATE DAY AND STRENGTHENING TO NEAR 15KTS BY THE AFTERNOON AS THE SURFACE PRESSURE GRADIENT TIGHTENS. OTHER THAN PASSING MID AND HIGH LEVEL CLOUDS...ANTICIPATE MOSTLY SUNNY SKIES THROUGHOUT THE DAY. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...CP NEAR TERM...CP SHORT TERM...CP LONG TERM....PUMA AVIATION...RYAN VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
ISSUED BY NATIONAL WEATHER SERVICE LA CROSSE WI 539 PM CST MON DEC 16 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 302 PM CST MON DEC 16 2013 MAIN SHORT TERM CONCERN IS ON SNOW POTENTIAL LATE TONIGHT INTO TUESDAY MORNING. CURRENTLY AS OF 21Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED RIDGING OVER THE WESTERN U.S. INTO BRITISH COLUMBIA WHILE TROUGHING DOMINATED EASTERN CANADA AND IN GENERAL THE EASTERN U.S.. WITHIN THIS TROUGHING...TWO SHORTWAVES WERE NOTED OVER SOUTHERN MINNESOTA AND IN NORTH DAKOTA. THE SHORTWAVE OVER SOUTHERN MINNESOTA WAS PRODUCING A BAND OF SNOW ON RADAR MARCHING ACROSS WISCONSIN... CLIPPING PORTIONS OF NORTHEAST IOWA INTO NORTHERN ILLINOIS. THE NEXT AREA OF SNOW EXISTS OVER EASTERN MONTANA INTO WESTERN NORTH DAKOTA...ON THE WEST SIDE OF THE SHORTWAVE THERE. THIS BAND OF SNOW IS BEING PRODUCED MORE BY MID-LEVEL FRONTOGENESIS AND UPPER DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A 110-130 KT JET STREAK IN NORTHEAST MONTANA PER RAP ANALYSIS. CLOSER TO THE FORECAST AREA...COMBINATION OF LOW SUN ANGLE AND A SURFACE RIDGE OF HIGH PRESSURE IN PLACE HAS BEEN LIMITING MIXING...KEEPING A STRATUS DECK IN PLACE FOR MUCH OF THE DAY. THE AIRMASS IS ALSO COOL IN A SHALLOW LAYER...SINCE 850MB TEMPS RANGE FROM 4C TO -4C SOUTHWEST TO NORTHEAST ACROSS THE FORECAST AREA. 12Z DVN SOUNDING REALLY REFLECTS THE SHALLOW COOL LAYER AND THE STRATUS WITH A SATURATED VERY STRONG INVERSION BETWEEN 925MB AND 825MB. FOCUS IS ON THE SHORTWAVE COMING OUT OF NORTH DAKOTA...ALONG WITH THE MID LEVEL FRONTOGENESIS AND UPPER JET STREAK ON ITS WESTERN SIDE...WHICH ARE PROGGED TO DIG SOUTHEAST TO DUBUQUE BY 12Z TUESDAY. MODELS ARE IN VERY GOOD AGREEMENT ON ALL OF THE AFOREMENTIONED FEATURES THUS HAVE FOLLOWED THE CONSENSUS. WE SHOULD SEE A DRY EVENING AREA WIDE...THEN THE BAND OF SNOW UP IN WESTERN NORTH DAKOTA WILL ARRIVE GENERALLY TO LOCATIONS ALONG/NORTH OF US-20. RAISED PRECIPITATION CHANCES UP TO 70 IN THIS AREA...AND EVEN INCLUDED SOME CHANCES A BIT FARTHER SOUTH TOWARDS BUT NOT TO THE I-80 CORRIDOR IN THE EVENT THE BAND SLIPS A BIT FARTHER SOUTH. MUCH OF THE SNOW LOOKS TO BE CONFINED BETWEEN 06-12Z TUESDAY...WITH PERHAPS A LITTLE SNOW LINGERING IN NORTHWEST ILLINOIS BETWEEN 12-14Z BEFORE IT PUSHES OFF TO THE EAST. TOTAL SNOW AMOUNTS MAY BE UPWARDS OF 1/2 INCH TO 1 INCH...HIGHEST NEAR DUBUQUE. OTHER ISSUES OF NOTE IN THE SHORT TERM. 1. WINDS PICKING UP IN THE WAKE OF THE SHORTWAVE PASSAGE. THE PRESSURE GRADIENT IS PROGGED TO REALLY TIGHTEN UP TUESDAY MORNING...RESULTING IN WEST TO NORTHWEST SPEEDS OF 15 TO 25 MPH WITH GUSTS PERHAPS APPROACHING 35 MPH. WINDS DO NOT LOOK TO RELAX UNTIL LATE IN THE DAY WITH DIURNAL COOLING AND THE APPROACH OF A SURFACE RIDGE AXIS. THE WINDS COULD BLOW SOME OF THE SNOW AROUND THAT FALLS TONIGHT INTO TUESDAY MORNING. 2. CLOUDS. THE STRATUS DECK CURRENTLY IN PLACE LOOKS TO CLEAR OUT THIS EVENING AS WINDS SHIFT WEST...DRAWING DRIER AIR IN OUT OF NEBRASKA AND WESTERN IOWA. SKIES HAVE BEEN CLEARING IN WESTERN IOWA ALL DAY REFLECTING THE DRY AIR. CLOUDS SHOULD TEMPORARILY INCREASE WITH THE APPROACH OF THE NORTH DAKOTA SNOW BAND...THEN DECREASE AGAIN ON TUESDAY IN ITS WAKE. 3. TEMPERATURES. IF WINDS CAN DECOUPLE THIS EVENING WHEN SKIES ARE CLEAR...READINGS COULD DIP INTO THE SINGLE DIGITS. CONFIDENCE IS NOT HIGH ENOUGH TO GO THAT COLD...THUS STAYED CLOSER TOWARDS THE CONSENSUS. HIGHS DEFINITELY WARMER TOMORROW WITH MORE SUN AND WINDS FOR MIXING...THOUGH 850MB TEMPS ARE COOLER BETWEEN -8 AND -10C. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 302 PM CST MON DEC 16 2013 MAIN LONG TERM FORECAST CONCERNS ARE ON PRECIPITATION TYPES WEDNESDAY NIGHT THROUGH FRIDAY...AND AGAIN SATURDAY INTO SUNDAY. MODELS REMAIN CONSISTENT IN SHOWING A MAJOR PATTERN CHANGE OVER THE NEXT FEW DAYS...RESULTING FROM A POTENT TROUGH DIGGING DOWN FROM NORTHERN BRITISH COLUMBIA AT 00Z WEDNESDAY TO SOUTHERN CALIFORNIA BY 00Z FRIDAY. THIS MODULATES THE PATTERN DOWNSTREAM OVER THE FORECAST AREA FROM NORTHWEST FLOW ON TUESDAY...TO ZONAL ON WEDNESDAY...AND FINALLY SOUTHWESTERLY ON THURSDAY. IN RESPONSE TO THIS PATTERN CHANGE...WARM ADVECTION IS EXPECTED...WITH MOISTURE ADVECTION COMING INTO PLAY AS WELL ONCE HIGH PRESSURE MOVES OUT OF THE WAY OF THE GULF OF MEXICO COME WEDNESDAY. AFTER WHAT WILL BE QUIET WEATHER TUESDAY NIGHT AND WEDNESDAY... THINGS GET MORE INTERESTING FOR WEDNESDAY NIGHT AND THURSDAY. 16.12Z NAM/GFS/ECMWF ALL SHOW LOW LEVEL SATURATION TAKING PLACE WEDNESDAY NIGHT...WITH THE DEPTH OF THE SATURATION GROWING IN TIME THROUGH THURSDAY. AS HIGHER MOISTURE IMPINGES ON THE COOLER...SNOW PACK OVER THE AREA...ANTICIPATING AREAS OF FOG TO DEVELOP WEDNESDAY EVENING. MAY EVENTUALLY NEED A DENSE FOG ADVISORY. IN ADDITION...THERE COULD EVEN BE SOME DRIZZLE IN THIS FOG WEDNESDAY NIGHT...AS SUGGESTED BY THE 16.12Z NAM QPF FIELDS...BUT CONFIDENCE IS TOO LOW TO MENTION PRIOR TO 12Z THURSDAY. BETTER MODEL AGREEMENT AFTER 12Z THURSDAY FOR DEEPER LOW LEVEL MOISTURE AND THE ISENTROPIC LIFT DOES GRADUALLY INCREASE. THUS...PRECIPITATION CHANCES INCREASE THROUGH THE DAY THURSDAY. SOUNDINGS DEPICT NO ICE IN THE CLOUDS...THUS ANY PRECIPITATION THAT FALLS WILL BE IN LIQUID FORM...WITH THE SURFACE AND POSSIBLY EVEN GROUND TEMPERATURE DICTATING WHETHER IT FREEZES ON CONTACT. IT DOES SEEM THAT THE GREATER ICING THREAT WOULD BE NORTH OF I-80 THURSDAY MORNING...SINCE TEMPERATURES IN MOST PLACES ALONG/SOUTH OF I-80 MAY STRUGGLE TO FALL BELOW FREEZING WEDNESDAY NIGHT. A COLD FRONTAL BOUNDARY IS PROGGED TO SLOWLY SLIDE SOUTHEAST THROUGH THE FORECAST AREA ON THURSDAY...WHICH COMBINED WITH DAYTIME HEATING SHOULD HELP TO GET RID OF THE FOG. AS WE HEAD TOWARDS THE WEEKEND...MODELS ARE IN GOOD AGREEMENT SPLITTING UP THAT WESTERN TROUGH. THE NORTHERN PORTION SHORTWAVE TROUGH IS PROGGED TO SLIDE ACROSS MN AND WI...WHICH SIMULTANEOUSLYBRINGS A SURFACE LOW NORTHEAST THROUGH THE FORECAST AREA. PRECIPITATION SHOULD INTENSIFY SOME AHEAD OF THE SURFACE LOW...ENOUGH TO WARRANT HIGHER PRECIPITATION CHANCES. THE PRECIPITATION THEN EXITS OFF TO THE EAST FRIDAY WITH THE PASSAGE OF THE TROUGH. AGAIN...NO ICE IS SUGGESTED IN THE CLOUDS...MEANING EITHER RAIN OR FREEZING RAIN AT THE SURFACE DEPENDING ON THE SURFACE TEMPERATURE. FOCUS THEN SHIFTS TO THE SOUTHERN PORTION OF THE WESTERN TROUGH...WHICH THE 16.12Z ECMWF/CANADIAN/GFS ALL SHOW LIFTING UP THROUGH THE CENTRAL PLAINS AND ILLINOIS SATURDAY INTO SUNDAY. WE NEED TO WATCH THIS SHORTWAVE AND ASSOCIATED SYSTEM CLOSELY FOR SNOW...SLEET AND FREEZING RAIN. THE THREAT FOR SLEET AND FREEZING RAIN RIGHT NOW SEEMS TO BE HIGHEST SOUTHEAST OF A LINE FROM ROCK FALLS TO MOLINE IL AND MT. PLEASANT IA. RAISED PRECIPITATION CHANCES IN THIS AREA TOO FOR SATURDAY NIGHT TOWARDS 60 AS MODELS ARE COMING INTO BETTER AGREEMENT. COLDER AND DRIER AIR WILL FILTER IN BEHIND THIS SYSTEM FOR SUNDAY NIGHT AND MONDAY AS AN ARCTIC HIGH PRESSURE AREA BUILDS SOUTH INTO THE REGION. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING) ISSUED AT 539 PM CST MON DEC 16 2013 TROUGH OR WEAK WARM FRONT ASSOCIATED WITH SHORT WAVE MOVING ACROSS ONTARIO MOVING THROUGH THE AREA EARLY THIS EVENING. IFR CONDITIONS DEVELOPED AHEAD OF THIS FEATURE EARLIER BUT AS WESTERLY LOW LEVEL FLOW TAKES OVER THIS EVENING...EXPECT IMPROVING CONDITIONS. ANOTHER WEAK IMPULSE WITH Q-G FORCING COULD BRING ANOTHER SHOT OF SNOW TO MAINLY NORTH AREAS LATER TONIGHT BUT MINIMAL IMPACT FURTHER SOUTH. WHILE MVFR CONDITIONS COULD DEVELOP AT KDBQ...EXPECT MAINLY VFR CONDITIONS TO PREVAIL LATER TONIGHT AT OTHER SITES. && .DVN WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...SHEA
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
1025 PM EST TUE DEC 17 2013 .UPDATE... ISSUED AT 1025 PM EST TUE DEC 17 2013 DID A QUICK UPDATE TO ADD SOME LOW CLOUDS INTO THE NORTHERN PARTS OF THE CWA AS THAT LAST WAVE PASSES BY TO THE NORTHEAST OVERNIGHT. DID ALSO UPDATE THE AVIATION GRIDS TO REFLECT THESE MVFR CIGS. FINE TUNED OVERNIGHT LOWS IN LIGHT OF THE COLD TO NEUTRAL ADVECTION OVERNIGHT AND NORTHERN CLOUDS. THESE UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. UPDATE ISSUED AT 650 PM EST TUE DEC 17 2013 23Z SFC ANALYSIS SHOWS A DEPARTING AREA OF LOW PRESSURE...WITH A TIGHT AND COMPACT PRESSURE GRADIENT...EXITING KENTUCKY. THIS IS TAKING A BATCH OF LIGHT RAIN...AND SNOW ON THE NORTHERN FRINGE... EAST AND OUT OF THE AREA...AS WELL. THE LATEST HIGH RESOLUTION MODELS SUPPORT THIS TREND WITH THE HRRR AND RUC13 ESSENTIALLY DRY THROUGH THE REST OF THE NIGHT. HIGH PRESSURE BUILDING INTO EAST KENTUCKY WILL CLEAR MOST OF THE CLOUDS OUT OF THE SKY LEAVING BEHIND JUST A SMATTERING OF MID LEVELS ONES THAT COULD PRODUCE A FEW FLURRIES THROUGH THE REST OF THE EVENING. OTHERWISE...IT WILL BE DRIER AND COLDER OVERNIGHT WITH TEMPERATURES FALLING INTO THE MID 20S BY EARLY WEDNESDAY MORNING. HAVE UPDATED THE GRIDS TO REFLECT THIS MAKING CHANGES PRIMARILY TO THE POPS AND WX ONES AND T/TD TO A LESSER EXTENT. THESE HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. UPDATES TO THE ZFP AND HWO WILL BE ISSUED SHORTLY...ONCE THE MEASURABLE PCPN CLEARS THE CWA WITHIN THE HOUR. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT) ISSUED AT 331 PM EST TUE DEC 17 2013 MODELS HAVE BEEN CHANGING THROUGHOUT THE LAST 24 HOURS...MAKING IT HARD TO PINPOINT AN EXACT FORECAST UNTIL LOOKING AT ONGOING CONDITIONS. SO FAR TODAY...THE HRRR SEEMS TO BE INITIALIZING THE BEST WITH ONGOING CONDITIONS...AND THE OTHER HIRES MODELS HAVE FOLLOWED SUIT THROUGHOUT THE DAY. BASED ON CURRENT TRENDS...AND LATEST HIRES MODEL DATA...FAVOR A LESS IMPACTFUL EVENING WITH MAINLY LIGHT RAIN...ENDING BEFORE MIDNIGHT IN MOST AREAS. WITH TEMPERATURES WELL ABOVE FREEZING IN MOST LOCATIONS RIGHT NOW...AND ROAD TEMPS SITTING ABOVE FREEZING AS WELL...DO NOT EXPECT ANY IMPACTS OTHER THAN SOME LIGHT RAIN...MAINLY NORTH OF THE MOUNTAIN PARKWAY. CLOUD COVER CURRENTLY EXTENDS SOUTHWARD ACROSS MUCH OF THE CWA. AS PRECIPITATION QUICKLY MOVES OFF TO THE EAST...TEMPERATURES WILL COOL WITH LOSS OF DAYTIME HEATING...BUT LATEST DATA SUPPORTS THE IDEA THAT TEMPS WILL STILL BE ABOVE FREEZING THROUGH MOST OF THE EVENING. ANY SNOW THAT DOES FALL WILL BE LATE IN THE EVENING ACROSS THE FAR EASTERN CWA /PIKE COUNTY/...AS WELL AS ACROSS SOME OF THE HIGHEST TERRAIN NEAR THE VIRGINIA BORDER. DROPPED SNOW TOTALS SUBSTANTIALLY...WITH ONLY A COUPLE TENTHS EXPECTED IN THE HIGHEST TERRAIN. NEIGHBORING OFFICES SEEM TO HAVE FOLLOWED SUIT WITH THIS LOWER IMPACT SOLUTION AS WELL. THE PRECIPITATION SHOULD CLEAR EARLY IN THE NIGHT...WITH DRY AND COLDER AIR FILTERING IN BEHIND...EFFECTIVELY CUTTING OFF THE CLOUD COVER FROM WEST TO EAST. AS THIS COLDER AIRMASS TAKES HOLD...AND CLOUDS CLEAR...EXPECT TEMPS TO MIX OUT OVERNIGHT INTO THE MID 20S ACROSS MUCH OF THE REGION. SUNNY SKIES WILL FINALLY MAKE AN APPEARANCE DURING THE DAY TOMORROW AS HIGH PRESSURE REMAINS IN CONTROL. TEMPERATURES WILL BE ON THE COOLER SIDE COMPARED TO TODAY...BUT WILL STILL BE ABLE TO WARM UP TO ABOUT THE 40 DEGREE MARK. NAM12 FORECAST SOUNDINGS SHOW THE ATMOSPHERE BECOMING QUITE DRY...WITH DEW POINTS DROPPING SUBSTANTIALLY. THIS WILL ESPECIALLY BE THE CASE IN THE HIGHER TERRAIN WEDNESDAY NIGHT...WHERE DEW POINTS COULD DROP AS LOW AS 9 DEGREES. OVERNIGHT LOW TEMPS WILL DROP TO AROUND FREEZING OR SLIGHTLY BELOW...WITH A GOOD SET UP FOR A RIDGE VALLEY SPLIT TO OCCUR. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 341 PM EST TUE DEC 17 2013 THE EXTENDED FORECAST PERIOD BEGINS ON THURSDAY WITH A MAINLY ZONAL PATTERN OVER THE CONUS WITH AN UPPER LEVEL LOW OVER THE SOUTHWEST. THE BIG QUESTION BECOMES THE TIMING OF THE UPPER LOW AS IT MOVES TO THE EAST AND WHERE THE FRONT SETS UP OVER THE OHIO VALLEY. THE CURRENT TREND IN THE MODELS IS FOR A STRONGER LOW TO FORM ON THE FRONT TO THE WEST OF THE AREA. THIS SOLUTION WILL CREATE A SHARP WAVE ON THE FRONT AND PUSH A WARM FRONT TO THE NORTH OF THE AREA. THIS SOLUTION WOULD PRODUCE MUCH LESS RAINFALL BECAUSE THE STATIONARY FRONT WOULD STAY TO THE WEST AND NORTH OF EASTERN KENTUCKY. THE JURY IS REALLY STILL OUT ON THIS SOLUTION AND WOULD NOT BE TOO SURPRISED TO SEE A COUPLE DIFFERENT SOLUTIONS BEFORE THE WEEKEND GETS HERE. AS SUCH...TIMING OF THE SYSTEM AND THE AMOUNT OF RAINFALL IS FAIRLY LOW CONFIDENCE. IN ADDITION...HAVE SEEN THE MODELS STRUGGLE TIME AND TIME AGAIN WITH TRYING TO NAIL DOWN TRANSITIONS IN THE PATTERN LIKE THE ONE WE ARE SEEING. DID TREND THE FORECAST TO THE NEWER MODEL BLEND. ALSO WITH THIS SOLUTION...THERE WILL NOT BE MUCH TIME TO GET ANY COLD AIR INTO THE AREA AS THE FRONT MOVES THROUGH. THIS WILL DECREASE THE CHANCES FOR WINTRY PRECIPITATION ON THE BACK END OF THE FRONT. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 645 PM EST TUE DEC 17 2013 CONDITIONS ARE RAPIDLY IMPROVING THROUGH THE FORECAST AREA AS HIGH PRESSURE MOVES IN FROM THE WEST AND THE LINGERING PCPN/LOWER CLOUDS EXIT TO THE EAST. VFR CONDITIONS WILL FOLLOW FOR THE REST OF THE PERIOD. A TIGHT PRESSURE GRADIENT WITH THE PASSING LOW WILL RELAX OVER THE NEXT SEVERAL HOURS ALSO SETTLING THE BRISK NORTHWEST WINDS TO WEST ONES AT BETWEEN 5 AND 10 KTS. THIS IS REFLECTED IN THE TAFS AND GRIDS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...JMW LONG TERM...JJ AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
650 PM EST TUE DEC 17 2013 .UPDATE... ISSUED AT 650 PM EST TUE DEC 17 2013 23Z SFC ANALYSIS SHOWS A DEPARTING AREA OF LOW PRESSURE...WITH A TIGHT AND COMPACT PRESSURE GRADIENT...EXITING KENTUCKY. THIS IS TAKING A BATCH OF LIGHT RAIN...AND SNOW ON THE NORTHERN FRINGE... EAST AND OUT OF THE AREA...AS WELL. THE LATEST HIGH RESOLUTION MODELS SUPPORT THIS TREND WITH THE HRRR AND RUC13 ESSENTIALLY DRY THROUGH THE REST OF THE NIGHT. HIGH PRESSURE BUILDING INTO EAST KENTUCKY WILL CLEAR MOST OF THE CLOUDS OUT OF THE SKY LEAVING BEHIND JUST A SMATTERING OF MID LEVELS ONES THAT COULD PRODUCE A FEW FLURRIES THROUGH THE REST OF THE EVENING. OTHERWISE...IT WILL BE DRIER AND COLDER OVERNIGHT WITH TEMPERATURES FALLING INTO THE MID 20S BY EARLY WEDNESDAY MORNING. HAVE UPDATED THE GRIDS TO REFLECT THIS MAKING CHANGES PRIMARILY TO THE POPS AND WX ONES AND T/TD TO A LESSER EXTENT. THESE HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. UPDATES TO THE ZFP AND HWO WILL BE ISSUED SHORTLY...ONCE THE MEASURABLE PCPN CLEARS THE CWA WITHIN THE HOUR. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT) ISSUED AT 331 PM EST TUE DEC 17 2013 MODELS HAVE BEEN CHANGING THROUGHOUT THE LAST 24 HOURS...MAKING IT HARD TO PINPOINT AN EXACT FORECAST UNTIL LOOKING AT ONGOING CONDITIONS. SO FAR TODAY...THE HRRR SEEMS TO BE INITIALIZING THE BEST WITH ONGOING CONDITIONS...AND THE OTHER HIRES MODELS HAVE FOLLOWED SUIT THROUGHOUT THE DAY. BASED ON CURRENT TRENDS...AND LATEST HIRES MODEL DATA...FAVOR A LESS IMPACTFUL EVENING WITH MAINLY LIGHT RAIN...ENDING BEFORE MIDNIGHT IN MOST AREAS. WITH TEMPERATURES WELL ABOVE FREEZING IN MOST LOCATIONS RIGHT NOW...AND ROAD TEMPS SITTING ABOVE FREEZING AS WELL...DO NOT EXPECT ANY IMPACTS OTHER THAN SOME LIGHT RAIN...MAINLY NORTH OF THE MOUNTAIN PARKWAY. CLOUD COVER CURRENTLY EXTENDS SOUTHWARD ACROSS MUCH OF THE CWA. AS PRECIPITATION QUICKLY MOVES OFF TO THE EAST...TEMPERATURES WILL COOL WITH LOSS OF DAYTIME HEATING...BUT LATEST DATA SUPPORTS THE IDEA THAT TEMPS WILL STILL BE ABOVE FREEZING THROUGH MOST OF THE EVENING. ANY SNOW THAT DOES FALL WILL BE LATE IN THE EVENING ACROSS THE FAR EASTERN CWA /PIKE COUNTY/...AS WELL AS ACROSS SOME OF THE HIGHEST TERRAIN NEAR THE VIRGINIA BORDER. DROPPED SNOW TOTALS SUBSTANTIALLY...WITH ONLY A COUPLE TENTHS EXPECTED IN THE HIGHEST TERRAIN. NEIGHBORING OFFICES SEEM TO HAVE FOLLOWED SUIT WITH THIS LOWER IMPACT SOLUTION AS WELL. THE PRECIPITATION SHOULD CLEAR EARLY IN THE NIGHT...WITH DRY AND COLDER AIR FILTERING IN BEHIND...EFFECTIVELY CUTTING OFF THE CLOUD COVER FROM WEST TO EAST. AS THIS COLDER AIRMASS TAKES HOLD...AND CLOUDS CLEAR...EXPECT TEMPS TO MIX OUT OVERNIGHT INTO THE MID 20S ACROSS MUCH OF THE REGION. SUNNY SKIES WILL FINALLY MAKE AN APPEARANCE DURING THE DAY TOMORROW AS HIGH PRESSURE REMAINS IN CONTROL. TEMPERATURES WILL BE ON THE COOLER SIDE COMPARED TO TODAY...BUT WILL STILL BE ABLE TO WARM UP TO ABOUT THE 40 DEGREE MARK. NAM12 FORECAST SOUNDINGS SHOW THE ATMOSPHERE BECOMING QUITE DRY...WITH DEW POINTS DROPPING SUBSTANTIALLY. THIS WILL ESPECIALLY BE THE CASE IN THE HIGHER TERRAIN WEDNESDAY NIGHT...WHERE DEW POINTS COULD DROP AS LOW AS 9 DEGREES. OVERNIGHT LOW TEMPS WILL DROP TO AROUND FREEZING OR SLIGHTLY BELOW...WITH A GOOD SET UP FOR A RIDGE VALLEY SPLIT TO OCCUR. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 341 PM EST TUE DEC 17 2013 THE EXTENDED FORECAST PERIOD BEGINS ON THURSDAY WITH A MAINLY ZONAL PATTERN OVER THE CONUS WITH AN UPPER LEVEL LOW OVER THE SOUTHWEST. THE BIG QUESTION BECOMES THE TIMING OF THE UPPER LOW AS IT MOVES TO THE EAST AND WHERE THE FRONT SETS UP OVER THE OHIO VALLEY. THE CURRENT TREND IN THE MODELS IS FOR A STRONGER LOW TO FORM ON THE FRONT TO THE WEST OF THE AREA. THIS SOLUTION WILL CREATE A SHARP WAVE ON THE FRONT AND PUSH A WARM FRONT TO THE NORTH OF THE AREA. THIS SOLUTION WOULD PRODUCE MUCH LESS RAINFALL BECAUSE THE STATIONARY FRONT WOULD STAY TO THE WEST AND NORTH OF EASTERN KENTUCKY. THE JURY IS REALLY STILL OUT ON THIS SOLUTION AND WOULD NOT BE TOO SURPRISED TO SEE A COUPLE DIFFERENT SOLUTIONS BEFORE THE WEEKEND GETS HERE. AS SUCH...TIMING OF THE SYSTEM AND THE AMOUNT OF RAINFALL IS FAIRLY LOW CONFIDENCE. IN ADDITION...HAVE SEEN THE MODELS STRUGGLE TIME AND TIME AGAIN WITH TRYING TO NAIL DOWN TRANSITIONS IN THE PATTERN LIKE THE ONE WE ARE SEEING. DID TREND THE FORECAST TO THE NEWER MODEL BLEND. ALSO WITH THIS SOLUTION...THERE WILL NOT BE MUCH TIME TO GET ANY COLD AIR INTO THE AREA AS THE FRONT MOVES THROUGH. THIS WILL DECREASE THE CHANCES FOR WINTRY PRECIPITATION ON THE BACK END OF THE FRONT. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 645 PM EST TUE DEC 17 2013 CONDITIONS ARE RAPIDLY IMPROVING THROUGH THE FORECAST AREA AS HIGH PRESSURE MOVES IN FROM THE WEST AND THE LINGERING PCPN/LOWER CLOUDS EXIT TO THE EAST. VFR CONDITIONS WILL FOLLOW FOR THE REST OF THE PERIOD. A TIGHT PRESSURE GRADIENT WITH THE PASSING LOW WILL RELAX OVER THE NEXT SEVERAL HOURS ALSO SETTLING THE BRISK NORTHWEST WINDS TO WEST ONES AT BETWEEN 5 AND 10 KTS. THIS IS REFLECTED IN THE TAFS AND GRIDS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...JMW LONG TERM...JJ AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS PADUCAH KY
228 PM CST Mon Dec 16 2013 .SHORT TERM...(This Evening through Wednesday night) ISSUED AT 228 PM CST MON DEC 16 2013 We have finally gotten rid of the low level moisture and mainly clear skies are common across the Quad State. This is in stark contrast to conditions immediately north of our CWA, on the other side of a frontal boundary, where ceilings are below 1000 ft and visibilities are restricted and winds are northeasterly. The RAP13 keeps the bulk of the lower level moisture to our north/northeast throughout the rest of the day. If any low clouds do invade our area, it would be up in the EVV - tristate region. The aforementioned boundary to our north is progged to slide south across the region later today/this evening, as energy aloft to our northwest travels southeast in the NW flow. Not sure of the amount of cloudiness that will accompany the frontal passage, as the GFS is more robust with the low level moisture returning this evening. It appears as though a secondary boundary moves through the area during the morning hours on Tuesday and brings another possible wave of clouds. Not enough moisture in either frontal passage to worry about any precipitation. However, decent cold air advection will take place behind this secondary front and likely cause temperatures to be lower on Tuesday then today. While this was seen in the models yesterday, it appears as though the degree of cold air coming in is a bit more impressive. Low level temps (~925mb) drop back down to -7/-8 deg C by the end of the day Tuesday. Therefore, we might not get above 40 in our far northern counties and remain in the low to mid 40s elsewhere, with sfc high pressure centered over Springfield MO by 00Z Wed. This colder weather is definitely not here to stay however. We start to see warm air advection begin in earnest on Tuesday night...as high pressure slides southeast into the TN valley by 12Z Wednesday. High pressure continues to move southeast toward the southeast coast throughout the day, putting our area in increasing southwest flow. This should pump everyone well into the 40s and 50s for highs Wednesday. Guidance numbers seem a bit too cool, especially given how warm we are getting today, although we did start out warmer this morning. Tuesday nights lows via guidance seem too cold though and that is likely why they are lower for highs on Wednesday. It seems more logical that highs should top out in the upper 40s to mid 50s. .LONG TERM...(Thursday through Monday) ISSUED AT 228 PM CST MON DEC 16 2013 The latest long range models are in general agreement, that a frontal boundary will enter into the area Friday, then slow down through Saturday night, then push east of the area on Sunday as low pressure tracks NE from the Ozarks to the Ohio Valley region. Mild temperatures are forecast Thursday through Saturday. Turning colder again Sunday. Scattered showers are forecast as early as Thursday night into Friday as weak mid level support, increased moisture and low level warm advection support the chance. Upper system is forecast to track across Old Mexico, then turn NE into the southern Plains and eventually mid Mississippi Valley region over the weekend. An increase in moisture and ascent is expected Friday night through Saturday night, with periods of showers (and a few thunderstorms given the persistent elevated instability forecast). Locally heavy rain appears a good possibility given the forecast upper air pattern supports this scenario. Forecast precipitable water values are expected to exceed 1.5" which is above the 99th percentile for this time of year. Still time for the models to adjust and lock in. So expect adjustments and such as we progress through the week. Could be a window of opportunity for strong storms late Saturday night into Sunday morning if the aforementioned low tracks along the Ohio River. Some of the models show very strong wind fields and a hint of surface based instability, mainly over west KY. Will see. Again, adjustments will likely be made. Falling temps expected Sunday in the wake of the front. Cannot rule out very light snow or flurries on the backside of the system late Sunday / Sunday night. Will not play this up at all, as the models show decreasing moisture in the confluence region of the phasing positive tilt mid level trof over the nation`s mid section. Dry and cold weather is forecast Monday with high pressure back across the area. && .AVIATION... ISSUED AT 1037 AM CST MON DEC 16 2013 SSW winds today up to 10 kts, with just a few mid/high clouds. Confidence in lower clouds tonight is low. NAM guidance more suggestive of low clouds, fog potential than the GFS. The RAP shows moisture near surface, dry aloft. Should winds become light enough and with more snow melt today, will have to monitor for low cloud and/or patchy fog potential. For now, just a hedge forecast in that direction. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...NONE. IN...NONE. KY...NONE. && $$ SHORT TERM...CW LONG TERM...CN
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1037 AM CST Mon Dec 16 2013 .SHORT TERM...(Today through Wednesday) ISSUED AT 348 AM CST MON DEC 16 2013 Low clouds have cleared much of the region early this morning, with the exception of perhaps a few locations in the Evansville tri-state area. The low clouds were replaced by mid level clouds accompanying the passage of a mid level disturbance overnight. Model guidance indicates these clouds should clear the region from west to east through the morning. Some redevelopment of low clouds is possible by late morning and afternoon with lingering low level moisture still in place. However, their impact should gradually lessen as we progress towards mid week. Over the last 24 hours, we have expressed some concern for fog development for the next few nights as low level warm advection develops over top a cold moist snow covered ground. Despite what some raw model guidance was suggesting last night, little to no fog has formed over southeast Missouri thus far. Winds have stayed up overnight, but this should not inhibit the advection fog process we thought might occur. The air advecting into the region from the southwest is relatively dry, so that may be an inhibiting factor to fog formation instead, especially with a persistent light southwest wind. Similar conditions are expected tonight, so fog will hopefully not be much of an issue. Tuesday night may be a different story as light winds beneath a clear sky create more favorable conditions for radiation fog, particularly where any snow cover still exists. Low confidence precludes a mention in the forecast at this time - just something to keep in mind nonetheless. Below normal temperatures will persist today as the region remains in northwest flow aloft on the back side of a longwave trough over the east. However, a transition to a more zonal flow pattern by mid week will help to slowly moderate temperatures through the period. Highs by Tuesday should top the 40 degree mark in most locations, and possibly reach close to 50 degrees over southern portions of the area. Highs on Wednesday are expected to range from the upper 40s to mid 50s. Weak energy rotating across the Great Lakes may keep more sky cover in our northeastern counties through Tuesday, but this influence will lessen by Wednesday with more sunshine across the entire region. .LONG TERM...(Wednesday Night through Sunday) ISSUED AT 119 AM CST MON DEC 16 2013 We start the long term portion of the forecast with subtle shifts in the pattern that will lead to a moderation in temps. The upper level flow will be backing, as height falls in the southern Plains occur in response to a digging upper level jet. Downstream ridging will work in as upper level southwesterlies aid the moderation process. By Thursday, this moderating trend includes moisture, and elevated/overrunning pops begin to appear from the north and west, as a front will be taking shape and approach from that direction. Thursday night-Friday, we see surface dew point temps surging through the 50s, with 60F not far off. 850 mb winds have increased to 50 kts. Elevated instability parameters such as the K index suggest at least an isolated mention of thunder is still possible. Beyond Friday is where the model divergence takes place. However, despite the differing solutions, a trend of warmer layer threshold temps is starting to appear, as both the ECMWF/GFS have trended this direction the last two forecast nights. The ECMWF keeps a wetter forecast as the boundary still sets up/hangs in the vcnty thru the weekend, while the GFS moves it on thru before stalling/returning it. Both suggest mainly liquid pcpn chances by and large as a whole, although both also support a changeover before ending mention by late day 7 into day 8. && .AVIATION... ISSUED AT 1037 AM CST MON DEC 16 2013 SSW winds today up to 10 kts, with just a few mid/high clouds. Confidence in lower clouds tonight is low. NAM guidance more suggestive of low clouds, fog potential than the GFS. The RAP shows moisture near surface, dry aloft. Should winds become light enough and with more snow melt today, will have to monitor for low cloud and/or patchy fog potential. For now, just a hedge forecast in that direction. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...NONE. IN...NONE. KY...NONE. && $$
AREA FORECAST DISCUSSION
NWS PADUCAH KY
128 AM CST Mon Dec 16 2013 .UPDATE... ISSUED AT 1141 PM CST SUN DEC 15 2013 Updated aviation section for 06z TAF package. && .SHORT TERM...(This Evening through Tuesday Night) ISSUED AT 213 PM CST SUN DEC 15 2013 The short term forecast will continue to be a sky and temperature challenge, as no measureable precipitation is forecast with northwest flow aloft continuing. Plenty of remnant low level moisture has resulted in a prolonged period of cloudy skies early today. However, by mid morning, progress was being made in clearing skies in parts of southeast MO. The RAP model seemed to be doing the best with regards to the low level moisture departing that area. It indicates that the clearing will continue across southeast MO and maybe a bit further east into southwest IL/KY However, upstream cloudiness from disturbances aloft will likely keep most of southern IL, southwest IN and a good chunk of western KY in the clouds through tonight into Monday. Weak warm air advection will start up in southeast MO later today and into tonight. As this weak warm advection develops over top a cold moist snow covered ground, we could be looking at fog potential, as noted by the previous shift. Fog will be most prevalent in areas where the clouds have cleared and stay clear. Therefore, we expect the greatest fog potential in southeast MO. It will be tricky though because there is quite a bit of low level moisture upstream yet to travel down this way so pinpointing what areas might stay partly cloudy vs cloudy will be difficult, especially when mid clouds are expected later tonight as well. Interestingly enough, the 12Z SREF indicates the best chance for fog development, especially after 06Z tonight, in SEMO/far southwest IL. However, numerical guidance is not as hot on the idea. Will opt for patchy fog wording in SEMO for now and let the evening shift adjust as need be. Although no precipitation is forecast for tonight, weak disturbances in the flow are going to bring some mid level moisture. Northern neighboring WFOs have flurries/light snow forecast for tonight. Looking at soundings/mid level moisture plots in our area, there does appear to be enough moisture aloft (especially around 06Z)to produce snowflakes but the atmosphere is very dry below 750mb. But in our extreme northern counties, the 18Z NAM indicates there just might be enough moisture and we could wet bulb enough to produce a few flurries up north of the I-64 corridor but most of the activity should stay to our north, where the better moisture will be. Monday through Tuesday, below normal temperatures will persist as the region remains in northwest flow aloft on the back side of a longwave trough over the east. Minor disturbances traveling through this NW flow will likely bring us intermittent clouds but no precipitation is currently forecast...with the cloudiest areas being southern IL, southwest IN and parts of west KY. Finally, we start to get rid of this low level moisture Monday night into Tuesday across a good part of the area. We will also see robust warm air advection take place Tuesday night, which will start our big warm up. .LONG TERM...(Wednesday Night through Sunday) ISSUED AT 119 AM CST MON DEC 16 2013 We start the long term portion of the forecast with subtle shifts in the pattern that will lead to a moderation in temps. The upper level flow will be backing, as height falls in the southern Plains occur in response to a digging upper level jet. Downstream ridging will work in as upper level southwesterlies aid the moderation process. By Thursday, this moderating trend includes moisture, and elevated/overrunning pops begin to appear from the north and west, as a front will be taking shape and approach from that direction. Thursday night-Friday, we see surface dew point temps surging through the 50s, with 60F not far off. 850 mb winds have increased to 50 kts. Elevated instability parameters such as the K index suggest at least an isolated mention of thunder is still possible. Beyond Friday is where the model divergence takes place. However, despite the differing solutions, a trend of warmer layer threshold temps is starting to appear, as both the ECMWF/GFS have trended this direction the last two forecast nights. The ECMWF keeps a wetter forecast as the boundary still sets up/hangs in the vcnty thru the weekend, while the GFS moves it on thru before stalling/returning it. Both suggest mainly liquid pcpn chances by and large as a whole, although both also support a changeover before ending mention by late day 7 into day 8. && .AVIATION... ISSUED AT 119 AM CST MON DEC 16 2013 Lingering IFR cigs at KEVV/KOWB should move out soon. Broken mid level clouds are expected otherwise with occasional MVFR vsbys possible. After 14z, VFR conditions are expected through the day. Winds will be south to southwest at 5 to 10 kts through the TAF period. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...NONE. IN...NONE. KY...NONE. && $$
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1141 PM CST Sun Dec 15 2013 .UPDATE... ISSUED AT 1141 PM CST SUN DEC 15 2013 Updated aviation section for 06z TAF package. && .SHORT TERM...(This Evening through Tuesday Night) ISSUED AT 213 PM CST SUN DEC 15 2013 The short term forecast will continue to be a sky and temperature challenge, as no measureable precipitation is forecast with northwest flow aloft continuing. Plenty of remnant low level moisture has resulted in a prolonged period of cloudy skies early today. However, by mid morning, progress was being made in clearing skies in parts of southeast MO. The RAP model seemed to be doing the best with regards to the low level moisture departing that area. It indicates that the clearing will continue across southeast MO and maybe a bit further east into southwest IL/KY However, upstream cloudiness from disturbances aloft will likely keep most of southern IL, southwest IN and a good chunk of western KY in the clouds through tonight into Monday. Weak warm air advection will start up in southeast MO later today and into tonight. As this weak warm advection develops over top a cold moist snow covered ground, we could be looking at fog potential, as noted by the previous shift. Fog will be most prevalent in areas where the clouds have cleared and stay clear. Therefore, we expect the greatest fog potential in southeast MO. It will be tricky though because there is quite a bit of low level moisture upstream yet to travel down this way so pinpointing what areas might stay partly cloudy vs cloudy will be difficult, especially when mid clouds are expected later tonight as well. Interestingly enough, the 12Z SREF indicates the best chance for fog development, especially after 06Z tonight, in SEMO/far southwest IL. However, numerical guidance is not as hot on the idea. Will opt for patchy fog wording in SEMO for now and let the evening shift adjust as need be. Although no precipitation is forecast for tonight, weak disturbances in the flow are going to bring some mid level moisture. Northern neighboring WFOs have flurries/light snow forecast for tonight. Looking at soundings/mid level moisture plots in our area, there does appear to be enough moisture aloft (especially around 06Z)to produce snowflakes but the atmosphere is very dry below 750mb. But in our extreme northern counties, the 18Z NAM indicates there just might be enough moisture and we could wet bulb enough to produce a few flurries up north of the I-64 corridor but most of the activity should stay to our north, where the better moisture will be. Monday through Tuesday, below normal temperatures will persist as the region remains in northwest flow aloft on the back side of a longwave trough over the east. Minor disturbances traveling through this NW flow will likely bring us intermittent clouds but no precipitation is currently forecast...with the cloudiest areas being southern IL, southwest IN and parts of west KY. Finally, we start to get rid of this low level moisture Monday night into Tuesday across a good part of the area. We will also see robust warm air advection take place Tuesday night, which will start our big warm up. .LONG TERM...(Wednesday through Sunday) ISSUED AT 213 PM CST SUN DEC 15 2013 Will continue the forecast for an active weather regime late this week possibly extending into the weekend. Surface high pressure`s dominance on our FA will quickly fade as the high moves east toward the south Atlantic Coast by Wednesday evening. This will set the stage for southerly winds and a pronounced warm up Wednesday with the FA remaining in the warm sector until a cold front moves across the FA Friday. Both the ECMWF and GFS now bring this front through the FA Friday with the ECMWF now even a bit faster than the GFS. Will maintain small POPS across the west/NW part of the FA for Thursday and increase POPS slightly for Thursday night and Friday given the fairly consistent signal with the synoptic pattern through Friday. Will also keep a chance of thunderstorms for Thu night and Fri with K indices consistently AOA 30 for the last several model runs. Confidence with the post frontal part of the forecast remains more uncertain given major model changes with the GFS in particular. This is due to forecasting the movement of the southwest U.S. upper low/trough which is much slower with the latest GFS run and therefore the significant change/lesser precip chances for the weekend as a result of the southeast progression of the surface cold front and subsequent post frontal drying. Will tend to lean more toward the ECMWF position of maintaining... including with the 12Z model run...ample moisture across our FA given its NE progression of the upper low. Precip type will once again be borderline with the often generalization of the N part of the FA having the best chance for wintry precip and areas near the MO/AR and KY/TN border having a greater likelihood of rain as supported by a blend of several thickness parameters. This is particularly valid of the late weekend precip ahead of the upper low...assuming this even materializes given the aforementioned model differences. Warm air advection will occur Wed-Fri until the cold front moves through the FA Friday. The trend has been even warmer temps for Thursday which is now forecast to be as warm as Friday with the exception of the southeast/Pennyrile area where a later passage of the cold front should result in Friday temps AOA 60. Back to more typical temps thereafter. && .AVIATION... ISSUED AT 1141 PM CST SUN DEC 15 2013 Lingering IFR cigs at KEVV/KOWB will move out by 08z. Broken mid level clouds are expected overnight with occasional MVFR vsbys possible. After 14z, VFR conditions are expected through the day. Winds will be south to southwest at 5 to 10 kts through the TAF period. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...NONE. IN...NONE. KY...NONE. && $$ AVIATION...RST
AREA FORECAST DISCUSSION...UPDATED
NWS GRAY ME
913 PM EST TUE DEC 17 2013 .SYNOPSIS... LOW PRESSURE WILL DEVELOP SOUTH OF LONG ISLAND THIS EVENING AND WILL INTENSIFY AS IT MOVES NORTHEAST THROUGH THE GULF OF MAINE OVERNIGHT. LOW PRESSURE WILL CONTINUE EAST INTO THE MARITIMES ON WEDNESDAY. A WEAK RIDGE OF HIGH PRESSURE WILL BUILD IN FROM THE WEST WEDNESDAY NIGHT AND WILL SHIFT EAST OF THE REGION EARLY THURSDAY. LOW PRESSURE CROSSING SOUTHERN CANADA ON THURSDAY WILL SWING A TRAILING COLD FRONT TOWARD THE REGION. THE FRONT WILL STALL AS IT PUSHES INTO SOUTHERN NEW ENGLAND THURSDAY NIGHT AND LOW PRESSURE WILL TRACK NORTHEAST ALONG IT ON FRIDAY. THE FRONT WILL REMAIN STALLED OVER THE REGION FRIDAY NIGHT AND SATURDAY. ANOTHER AREA OF LOW PRESSURE WILL TRACK NORTHEAST OUT OF THE LOWER MISSISSIPPI VALLEY SATURDAY NIGHT THROUGH MONDAY. && .NEAR TERM /THROUGH WEDNESDAY/... UPDATE...WELL DEVELOPED BAND OF HEAVY SNFL HAS ORGANIZED ALONG THE CWFA COASTLINE FROM KPSM...THRU KPWM...AND KRKD. WHILE SN WILL WIND DOWN FROM W TO E FOR SRN PORTIONS OF THE FORECAST AREA...OCCASIONALLY HEAVY SNFL WILL CONTINUE FROM KPWM NWD THRU MIDNIGHT. GIVEN RADAR TRENDS...FORECAST...AND SNFL OBSERVATIONS REPORTED SO FAR I HAVE ADDED SAGADAHOC COUNTY TO THE WARNINGS. ANOTHER 2-3 INCHES OR MORE IS POSSIBLE THERE IN PERSISTENT BANDING...WHICH SHOULD BRING THE MAJORITY OF THE COUNTY OVER 6 INCHES. ELSEWHERE HEADLINES LOOK GOOD...AND WILL BE MONITORING FOR EXPIRATIONS/CANCELLATIONS THRU MIDNIGHT. OTHERWISE...UPDATED POP WITH BLEND OF LATEST HRRR TO BETTER DEFINE BACK EDGE OF PCPN. PREVIOUS DISCUSSION...THE MAIN FORECAST CHALLENGE HAS BEEN TRYING TO FIGURE OUT WHERE THE AXIS OF HEAVY PRECIPITATION IS GOING TO SET UP...IE...WILL IT BE OVER LAND OR OUT OVER THE WATER. AS THE LOW CONTINUES TO DEEPEN AND MOVE NORTHEASTWARD AND THE MID LEVEL LOW CLOSES OFF...A BAND OF HEAVY SNOW SHOULD DEVELOP ON OR NEAR THE COASTAL PLAIN. WHILE THERE MAY BE A PERIOD OF 1-2 INCHES/HR SNOWFALL RATES ON THE COASTAL PLAIN THIS EVENING DUE TO EXCELLENT SNOW GROWTH AND STRONG FRONTOGENETICAL FORCING...SPEED OF THE SYSTEM IS A PRIMARY MITIGATING FACTOR IN WARNING-TYPE ACCUMS OVER HALF OR MORE OF ANY GIVEN ZONE. BASED ON CURRENT BUOY OBS AND POSITION OF COASTAL FRONT...AS WELL AS THE LATEST 12Z ECMWF AND VARIOUS MESOSCALE MODELS...HAVE DECIDED AGAINST UPGRADING THE ADVISORY TO A WARNING. THERE LOOKS TO BE QUITE THE TIGHT SNOWFALL GRADIENT FROM THIS...SO WOULDN/T BE SURPRISED IF ISOLATED 7 INCH SNOWFALL AMOUNTS OCCUR RIGHT ON THE COAST...WITH MUCH LESS AS YOU GET BACK TOWARD CENTRAL CUMBERLAND COUNTY FOR EXAMPLE. ON THE MID COAST OF MAINE...HAVE CONTINUED THE WARNING AS HIGHER PRECIP AMOUNTS ARE LIKELY THERE. OVERALL...EXPECTING A GENERAL 3 TO 6 INCHES IN THE ADVISORY AREA...WITH POTENTIAL FOR A LITTLE LESS THAN THAT ON THE WESTERN EDGE OF THE ADVISORY...AND THE 4 TO 6 INCH AMOUNTS ON THE IMMEDIATE COAST. IN THE WARNING AREA ON THE MID COAST...4 TO 8 INCHES WITH LOCALLY HIGHER AMOUNTS POSSIBLE. WINDS SHOULD BE RELATIVELY LIGHT SO BLOWING AND DRIFTING WILL BE MITIGATED EXCEPT PERHAPS FOR A TIME LATE THIS EVENING AND OVERNIGHT ON THE IMMEDIATE COAST. && .SHORT TERM /WEDNESDAY NIGHT/... ANY LINGERING LIGHT SNOW ON THE COAST WILL COME TO AN END EARLY WEDNESDAY MORNING AS THE LOW PULLS AWAY. OTHERWISE...FAIR LATER WED THROUGH WED NIGHT. && .LONG TERM /THURSDAY THROUGH TUESDAY/... LOW PRESSURE CROSSING SOUTHERN CANADA ON THURSDAY WILL SWING A TRAILING COLD FRONT TOWARD THE REGION. WILL SEE MOSTLY CLOUDY SKIES IN NORTHERN SECTIONS WITH LOW CHANCE POPS FOR AFTERNOON SNOW SHOWERS. DOWNWIND OF THE MOUNTAINS SKIES WILL BE PARTLY SUNNY. WILL ACTUALLY SEE TEMPS RISE ABOVE FREEZING IN SOUTHERN ZONES WHERE TEMPS WILL TOP OUT IN THE LOWER TO MID 30S. SLIGHTLY COOLER IN THE NORTH WITH MID 20S TO LOWER 30S. THE FRONT WILL GRADUALLY DROP SOUTH THURSDAY NIGHT AND WILL STALL OVER SOUTHERN NEW ENGLAND BY FRIDAY MORNING. ASIDE FROM A FEW SNOW SHOWERS IN THE NORTH AND POSSIBLY A STRAY FLURRY IN THE SOUTH MOST OF THE NIGHT WILL JUST FEATURE VARIABLE CLOUDS. LOW PRESSURE MOVING NORTHEAST OUT OF THE LOWER GREAT LAKES WILL TRACK ALONG THE STALLED FRONTAL BOUNDARY ON FRIDAY. FRONTAL BOUNDARY WILL BE THE FOCUS FOR OVER-RUNNING PRECIP AHEAD OF THIS SYSTEM WITH LIGHT SNOW QUICKLY TRANSITIONING TO MIXED PRECIP FRIDAY MORNING IN SOUTHERN ZONES BEFORE CHANGING TO RAIN IN THE AFTERNOON. MIXED PRECIP IN THE NORTH MAY LAST THROUGH THE AFTERNOON BEFORE TAPERING OFF IN THE EVENING AS LOW PRESSURE PUSHES EAST OF THE FORECAST AREA. WILL SEE A WIDE RANGE IN HIGH TEMPS WITH UPPER 20S TO MID 30S IN THE NORTH AND MID 30S TO LOWER 40S IN THE SOUTH. FRONT WILL REMAIN STALLED OVER SOUTHERN NEW ENGLAND FRIDAY NIGHT AND SATURDAY AS HIGH PRESSURE BUILDS BY TO THE NORTH. SHORTWAVE EJECTING OUT OF THE TEXAS AREA WILL ONCE AGAIN CRANK UP THE OVER-RUNNING ALONG THIS BOUNDARY SATURDAY AFTERNOON. MODELS BEGIN TO DIVERGE AT THIS POINT WITH THE ECMWF SETTING UP FARTHER NORTH WHILE THE GFS KEEPING THE FRONT FARTHER SOUTH. CONSIDERING SNOW PACK WOULD BE LEANING MORE TOWARD THE GFS SOLUTION. IN ANY CASE WILL LIKELY SEE SOME MIXED PRECIP OR LIGHT RAIN BREAKING OUT IN THE AFTERNOON. POTENTIAL WILL BE THERE FOR AN EXTENDED PERIOD OF FREEZING RAIN OR MIXED PRECIPITATION IN NORTHERN ZONES SATURDAY NIGHT AND SUNDAY AS LOW PRESSURE APPROACHES FROM THE WEST. SIGNIFICANT ICING MAY BE AN ISSUE WITH THIS SYSTEM. PRECIPITATION WILL WIND DOWN SUNDAY NIGHT AS BROAD AREA OF WEAK LOW PRESSURE EDGES IN FROM THE WEST. FRONT WILL GENERALLY REMAIN STALLED OVER THE SOUTHERN NEW ENGLAND ON MONDAY AS LOW PRESSURE REDEVELOPS IN THE VICINITY OF CAPE COD AND HEADS NORTHEAST. THIS MAY PRODUCE SOME AFTERNOON SHOWERS IN COASTAL ZONES BUT THESE SHOULD PUSH EAST BY EVENING AS THE FRONT PUSHES FARTHER SOUTH BEHIND DEPARTING LOW. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... SHORT TERM...CONDITIONS LOWER TO IFR IN SNOW THIS EVENING FOR MOST OF THE AREA. IMPROVEMENT IS FORESEEN WEDNESDAY AS LOW PRESSURE PULLS AWAY. VFR EXPECTED THEN. LONG TERM...VFR THURSDAY. MVFR/IFR CEILINGS/VSBY DEVELOPING FRIDAY...PERSISTING THROUGH SUNDAY. && .MARINE... SHORT TERM...GALES FOR THE OCEAN TONIGHT INTO EARLY WED AS LOW PRESSURE WRAPS UP OFF THE COAST. SCA FOR THE BAYS. SCA CONDITIONS LIKELY PERSIST THROUGH WEDNESDAY NIGHT IN CAA. LONG TERM...SCA`S LIKELY ON THURSDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR MEZ013- 014-019>021-024. WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR MEZ018- 023. WINTER STORM WARNING UNTIL 7 AM EST WEDNESDAY FOR MEZ022- 025>028. NH...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NHZ008>010-013-014. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST WEDNESDAY FOR ANZ151-153. GALE WARNING UNTIL 4 PM EST WEDNESDAY FOR ANZ150-152-154. && $$ NEAR TERM...LEGRO
AREA FORECAST DISCUSSION
NWS GRAY ME
651 PM EST TUE DEC 17 2013 .SYNOPSIS... LOW PRESSURE WILL DEVELOP SOUTH OF LONG ISLAND THIS EVENING AND WILL INTENSIFY AS IT MOVES NORTHEAST THROUGH THE GULF OF MAINE OVERNIGHT. LOW PRESSURE WILL CONTINUE EAST INTO THE MARITIMES ON WEDNESDAY. A WEAK RIDGE OF HIGH PRESSURE WILL BUILD IN FROM THE WEST WEDNESDAY NIGHT AND WILL SHIFT EAST OF THE REGION EARLY THURSDAY. LOW PRESSURE CROSSING SOUTHERN CANADA ON THURSDAY WILL SWING A TRAILING COLD FRONT TOWARD THE REGION. THE FRONT WILL STALL AS IT PUSHES INTO SOUTHERN NEW ENGLAND THURSDAY NIGHT AND LOW PRESSURE WILL TRACK NORTHEAST ALONG IT ON FRIDAY. THE FRONT WILL REMAIN STALLED OVER THE REGION FRIDAY NIGHT AND SATURDAY. ANOTHER AREA OF LOW PRESSURE WILL TRACK NORTHEAST OUT OF THE LOWER MISSISSIPPI VALLEY SATURDAY NIGHT THROUGH MONDAY. && .NEAR TERM /THROUGH WEDNESDAY/... UPDATE...LOW PRES CONTINUES TO DEVELOP INVOF CAPE COD AT THIS HOUR. WAA ALOFT IS SHARPENING THE MID LEVEL THERMAL BOUNDARY...AND RESULTING IN BANDS OF OCCASIONALLY HEAVY SNFL. CURRENTLY WATCHING ONE SUCH BAND TRANSLATING NWD FROM MIDDLESEX AND ESSEX COUNTIES IN MA. IT APPEARS TO BE CORRELATED WITH STRONGEST H8 FRONTOGENESIS ACCORDING TO MOST RECENT RAP FORECAST. THE WRN EXTENT OF THIS BAND IS PROGGED TO CONTINUE UP ALONG THE COAST TOWARDS DOWNEAST ME BY MORNING. THE INLAND EXTENT OF THAT HEAVIEST PCPN REMAINS UNCERTAIN...AS WELL AS THE FACT THAT BACK EDGE OF SNFL IS RAPIDLY APPROACHING FROM THE W. GIVEN THE CURRENT SPEED OF THINGS...I FEEL THAT HEADLINES ARE IN GOOD SHAPE. WILL MONITOR RADAR TRENDS FOR AREAS FROM PWM NEWD...AS THERE IS STILL A POSSIBILITY THAT LOW END WARNING CRITERIA IS MET. PREVIOUS DISCUSSION...THE MAIN FORECAST CHALLENGE HAS BEEN TRYING TO FIGURE OUT WHERE THE AXIS OF HEAVY PRECIPITATION IS GOING TO SET UP...IE...WILL IT BE OVER LAND OR OUT OVER THE WATER. AS THE LOW CONTINUES TO DEEPEN AND MOVE NORTHEASTWARD AND THE MID LEVEL LOW CLOSES OFF...A BAND OF HEAVY SNOW SHOULD DEVELOP ON OR NEAR THE COASTAL PLAIN. WHILE THERE MAY BE A PERIOD OF 1-2 INCHES/HR SNOWFALL RATES ON THE COASTAL PLAIN THIS EVENING DUE TO EXCELLENT SNOW GROWTH AND STRONG FRONTOGENETICAL FORCING...SPEED OF THE SYSTEM IS A PRIMARY MITIGATING FACTOR IN WARNING-TYPE ACCUMS OVER HALF OR MORE OF ANY GIVEN ZONE. BASED ON CURRENT BUOY OBS AND POSITION OF COASTAL FRONT...AS WELL AS THE LATEST 12Z ECMWF AND VARIOUS MESOSCALE MODELS...HAVE DECIDED AGAINST UPGRADING THE ADVISORY TO A WARNING. THERE LOOKS TO BE QUITE THE TIGHT SNOWFALL GRADIENT FROM THIS...SO WOULDN/T BE SURPRISED IF ISOLATED 7 INCH SNOWFALL AMOUNTS OCCUR RIGHT ON THE COAST...WITH MUCH LESS AS YOU GET BACK TOWARD CENTRAL CUMBERLAND COUNTY FOR EXAMPLE. ON THE MID COAST OF MAINE...HAVE CONTINUED THE WARNING AS HIGHER PRECIP AMOUNTS ARE LIKELY THERE. OVERALL...EXPECTING A GENERAL 3 TO 6 INCHES IN THE ADVISORY AREA...WITH POTENTIAL FOR A LITTLE LESS THAN THAT ON THE WESTERN EDGE OF THE ADVISORY...AND THE 4 TO 6 INCH AMOUNTS ON THE IMMEDIATE COAST. IN THE WARNING AREA ON THE MID COAST...4 TO 8 INCHES WITH LOCALLY HIGHER AMOUNTS POSSIBLE. WINDS SHOULD BE RELATIVELY LIGHT SO BLOWING AND DRIFTING WILL BE MITIGATED EXCEPT PERHAPS FOR A TIME LATE THIS EVENING AND OVERNIGHT ON THE IMMEDIATE COAST. && .SHORT TERM /WEDNESDAY NIGHT/... ANY LINGERING LIGHT SNOW ON THE COAST WILL COME TO AN END EARLY WEDNESDAY MORNING AS THE LOW PULLS AWAY. OTHERWISE...FAIR LATER WED THROUGH WED NIGHT. && .LONG TERM /THURSDAY THROUGH TUESDAY/... LOW PRESSURE CROSSING SOUTHERN CANADA ON THURSDAY WILL SWING A TRAILING COLD FRONT TOWARD THE REGION. WILL SEE MOSTLY CLOUDY SKIES IN NORTHERN SECTIONS WITH LOW CHANCE POPS FOR AFTERNOON SNOW SHOWERS. DOWNWIND OF THE MOUNTAINS SKIES WILL BE PARTLY SUNNY. WILL ACTUALLY SEE TEMPS RISE ABOVE FREEZING IN SOUTHERN ZONES WHERE TEMPS WILL TOP OUT IN THE LOWER TO MID 30S. SLIGHTLY COOLER IN THE NORTH WITH MID 20S TO LOWER 30S. THE FRONT WILL GRADUALLY DROP SOUTH THURSDAY NIGHT AND WILL STALL OVER SOUTHERN NEW ENGLAND BY FRIDAY MORNING. ASIDE FROM A FEW SNOW SHOWERS IN THE NORTH AND POSSIBLY A STRAY FLURRY IN THE SOUTH MOST OF THE NIGHT WILL JUST FEATURE VARIABLE CLOUDS. LOW PRESSURE MOVING NORTHEAST OUT OF THE LOWER GREAT LAKES WILL TRACK ALONG THE STALLED FRONTAL BOUNDARY ON FRIDAY. FRONTAL BOUNDARY WILL BE THE FOCUS FOR OVER-RUNNING PRECIP AHEAD OF THIS SYSTEM WITH LIGHT SNOW QUICKLY TRANSITIONING TO MIXED PRECIP FRIDAY MORNING IN SOUTHERN ZONES BEFORE CHANGING TO RAIN IN THE AFTERNOON. MIXED PRECIP IN THE NORTH MAY LAST THROUGH THE AFTERNOON BEFORE TAPERING OFF IN THE EVENING AS LOW PRESSURE PUSHES EAST OF THE FORECAST AREA. WILL SEE A WIDE RANGE IN HIGH TEMPS WITH UPPER 20S TO MID 30S IN THE NORTH AND MID 30S TO LOWER 40S IN THE SOUTH. FRONT WILL REMAIN STALLED OVER SOUTHERN NEW ENGLAND FRIDAY NIGHT AND SATURDAY AS HIGH PRESSURE BUILDS BY TO THE NORTH. SHORTWAVE EJECTING OUT OF THE TEXAS AREA WILL ONCE AGAIN CRANK UP THE OVER-RUNNING ALONG THIS BOUNDARY SATURDAY AFTERNOON. MODELS BEGIN TO DIVERGE AT THIS POINT WITH THE ECMWF SETTING UP FARTHER NORTH WHILE THE GFS KEEPING THE FRONT FARTHER SOUTH. CONSIDERING SNOW PACK WOULD BE LEANING MORE TOWARD THE GFS SOLUTION. IN ANY CASE WILL LIKELY SEE SOME MIXED PRECIP OR LIGHT RAIN BREAKING OUT IN THE AFTERNOON. POTENTIAL WILL BE THERE FOR AN EXTENDED PERIOD OF FREEZING RAIN OR MIXED PRECIPITATION IN NORTHERN ZONES SATURDAY NIGHT AND SUNDAY AS LOW PRESSURE APPROACHES FROM THE WEST. SIGNIFICANT ICING MAY BE AN ISSUE WITH THIS SYSTEM. PRECIPITATION WILL WIND DOWN SUNDAY NIGHT AS BROAD AREA OF WEAK LOW PRESSURE EDGES IN FROM THE WEST. FRONT WILL GENERALLY REMAIN STALLED OVER THE SOUTHERN NEW ENGLAND ON MONDAY AS LOW PRESSURE REDEVELOPS IN THE VICINITY OF CAPE COD AND HEADS NORTHEAST. THIS MAY PRODUCE SOME AFTERNOON SHOWERS IN COASTAL ZONES BUT THESE SHOULD PUSH EAST BY EVENING AS THE FRONT PUSHES FARTHER SOUTH BEHIND DEPARTING LOW. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... SHORT TERM...CONDITIONS LOWER TO IFR IN SNOW THIS EVENING FOR MOST OF THE AREA. IMPROVEMENT IS FORESEEN WEDNESDAY AS LOW PRESSURE PULLS AWAY. VFR EXPECTED THEN. LONG TERM...VFR THURSDAY. MVFR/IFR CEILINGS/VSBY DEVELOPING FRIDAY...PERSISTING THROUGH SUNDAY. && .MARINE... SHORT TERM...GALES FOR THE OCEAN TONIGHT INTO EARLY WED AS LOW PRESSURE WRAPS UP OFF THE COAST. SCA FOR THE BAYS. SCA CONDITIONS LIKELY PERSIST THROUGH WEDNESDAY NIGHT IN CAA. LONG TERM...SCA`S LIKELY ON THURSDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR MEZ013- 014-019>021-024-025. WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR MEZ018- 023. WINTER STORM WARNING UNTIL 7 AM EST WEDNESDAY FOR MEZ022- 026>028. NH...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NHZ008>010-013-014. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST WEDNESDAY FOR ANZ151-153. GALE WARNING UNTIL 4 PM EST WEDNESDAY FOR ANZ150-152-154. && $$ NEAR TERM...LEGRO
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
654 PM EST TUE DEC 17 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 343 PM EST TUE DEC 17 2013 NOTE THAT TEMPS AT CMX REMAIN QUESTIONABLE DUE TO FAULTY FAN ON OBSERVATION EQUIPMENT. TECHNICIANS WL BE WORKING ON THIS PROBLEM TMRW. 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW PERSISTENT NW FLOW ALF BTWN DEEP UPR TROF CENTERED OVER ONTARIO AND UPR RDG OVER WRN NAMERICA. H5 TEMPS WITHIN THE TROF EXTENDING INTO THE GREAT LKS ARE AS LO AS -40C...SO THE AREA REMAINS IN THE GRIP OF WINTER CHILL. ONE SHRTWV EMBEDDED WITHIN THE UPR TROF BROUGHT SOME -SN TO THE SCNTRL CWA THIS MRNG...BUT THIS DISTURBANCE/DEEPER MSTR SHOWN ON THE 12Z GRB RAOB HAVE SHIFTED TO THE E. ANOTHER SHRTWV IS PRESENT OVER MN... BUT THIS DISTURBANCE WL BE PASSING TOO FAR TO THE S TO HAVE AN IMPACT ON UPR MI. YET ANOTHER SHRTWV IS OVER NW ONTARIO AND DROPPING SEWD. ATTENDANT SFC-H85 COLD FNT MOVED INTO WRN UPR MI THIS AFTN. 12Z INL/YPL RAOBS SHOW HI RELATIVE RH TO H6-5 AND 12Z H85 TEMPS RANGING FM -13C AT INL RIGHT BEHIND THE COLD FNT TO -24C AT YPL... WHICH WAS DEEPER INTO THE COLD AIRMASS. SO THERE ARE POCKETS OF SHSN EXTENDING UPWIND OF LK SUP IN NRN MN/ADJOINING ONTARIO. FARTHER TO THE W...THERE ARE SIGNS THE FLOW IS BECOMING A BIT MORE PROGRESSIVE...AT LEAST FOR A SHORT TIME. 00Z-12Z H3 HGT RISES UP TO 150M WERE REPORTED AT SEVERAL UPR AIR SITES FM THE NRN PLAINS INTO SCNTRL CANADA AS THE WRN RDG SHIFTS TO THE E. MAIN FCST CONCERNS IN THE SHORT TERM FOCUS ON LES POPS/AMOUNTS WITH ARRIVAL OF MORE ARCTIC AIR BEHIND EARLY AFTN/EARLY EVNG COLD FROPA. TNGT...SHRTWV IN NW ONTARIO IS FCST TO SHIFT SEWD ACRS NRN LK SUP... ACCOMPANIED BY AREA OF WEAK H85-5 QVECTOR CNVGC/SOME DEEPER MSTR AND ATTENDANT COLD FROPA. EXPECT SHSN INTENSITY/COVERAGE TO INCRS LATE THIS AFTN/EVNG W-E...ESPECIALLY IN AREAS NEAR LK SUP FAVORED BY THE WNW FLOW IN THE WAKE OF THE COLD FROPA...WHICH WL BE FOLLOWED BY AXIS OF H85 TEMPS AS LO AS -20C. ALTHOUGH NOT OUT OF THE QUESTION THERE COULD BE SOME HEAVIER SHSN IN THE FAVORED SN BELTS...ADVY SN SEEMS UNLIKELY. THE FIRST LIMITING FACTOR WL BE RELATIVELY SHORT DURATION OF THE HEAVIER LES. HGT RISES NOTED IN THE NRN PLAINS/ SCENTRAL CANADA ARE PROGGED TO FOLLOW QUICKLY THE DEPARTING SHRTWV LATER IN THE EVNG WITH VIGOUROUS DNVA/DEEP LYR QVECTOR DVGC LOWERING SUBSIDENCE INVRN TO NEAR 3K FT OVER THE KEWEENAW BY 12Z. APRCH OF SFC RDG AXIS AND SHIFTING LLVL WINDS OVER THE W UNDER THESE NEGATIVE DYNAMICS...WITH RDG AXIS ARRIVING THERE BY 12Z...WL ALSO ACT TO SUPPRESS THE SN AMOUNTS. IN FACT...SUITE OF HIER RES MODEL OUTPUT IS QUITE VARIABLE ON QPF...WITH FCSTS INCONSISTENT ON MAGNITUDE/HGT/ TIMING OF SHARPER UVV AND RELATIVE TO THE DGZ. IN THE NW WIND SN BELTS TO THE E OF MQT...SHSN WL ARRIVE DURING THE EVNG AND PERSIST THRU 12Z. LONGER FETCH OVER THE OPEN WATER WL PLAY AN ENHANCEMENT ROLE IN INTENSIFYING THE SHSN STREAMING INTO THIS AREA...BUT SHIFTING WINDS MAY LIMIT THE RESIDENCE TIME OF THE HEAVIER SHSN HERE AS WELL. THE MOST FAVORABLE FACTOR FOR HEAVIER SN OVER THE ERN CWA NEAR LK SUP WL BE THE POTENTIAL FOR LAND BREEZE CNVGC OVER FAR EASTERN ALGER/NRN LUCE COUNTIES. BUT FCST SDNGS SHOW SUBSIDENCE INVRN SINKING FAIRLY STEADY HERE AS WELL LATER AT NGT WHEN THE POTENTIAL FOR THE SHARPER LLVL CNVGC WOULD BE GREATER. AS IS TYPICAL...AREAS OVER THE SCENTRAL WL SEE NOTHING MORE THAN ISOLD -SHSN WITH DOWNSLOPE FLOW. EXPECT THE LOWEST MIN TEMPS OVER THE INTERIOR W...WHERE THERE WL BE SOME CLRG/LIGHT WINDS WITH ARRIVAL OF SFC RDG AXIS. WED...AS THE UPR FLOW TENDS TO SHIFT MORE ZONAL...A SHRTWV IS FCST TO SHIFT E THRU SCENTRAL CANADA...WITH ASSOCIATED SFC LO PRES FCST TO MOVE INTO NRN MN BY 00Z THU. GENERAL WAD/ISENTROPIC LIFT BTWN THIS SHRTWV/SFC LO AND SFC HI SHIFTING INTO THE SE CONUS WL IMPACT THE UPR GRT LKS. AS THE FLOW BACKS TO THE SW...LINGERING LES OVER THE KEWEENAW AND FAR E CWA NEAR LK SUP WL SHIFT OUT INTO THE OPEN LK. THE BULK OF THE MODELS SHOW LGT SN ASSOCIATED WITH THE SHARPER ISENTROPIC ASCENT FALLING OVER LK SUP. THE CNDN MODEL IS THE ONE EXCEPTION...AS THIS MODEL SHOWS THE SFC LO A BIT FARTHER S IN MN AND STRIPE OF LGT -SN IMPACTING APPROXIMATELY THE NE HALF OF THE CWA. GIVEN PERSISTENCE OF TROF IN ERN CANADA AND CHILL...SUSPECT THIS MODEL IS ON THE RIGHT TRACK. SO WL SHIFT THE AXIS OF CHC POPS A BIT TO THE SW INTO THE NRN LAND CWA. FEED OF RELATIVELY DRY LLVL AIR WL LIMIT ANY POTENTIAL SN ACCUM EVEN IF THE MORE PESSIMISTIC CNDN MODEL DOES VERIFY. ALSO LOWERED FCST MAX TEMPS A BIT TO REFLECT THE POTENTIAL FOR MORE TENACIOUS COLD LLVL AIR. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 457 PM EST TUE DEC 17 2013 MUCH OF THIS FCST PERIOD IS IN THE MODERATE TO LOWER CONFIDENCE RANGE. AT 00Z THURSDAY MUCH OF THE CONTINENTAL U.S. WILL BE UNDER A BROAD WEAK RIDGE TO ZONAL FLOW AT 500MB...WITH THE DOMINANT LOW SPINNING ACROSS N CANADA WITH LONGWAVE TROUGHS EXTENDING ACROSS BOTH THE WEST AND EAST COASTS. AN INITIAL BROAD SFC LOW/TROUGH WILL EXTEND NE INTO CENTRAL LAKE SUPERIOR AT 00Z. WHILE THE GFS PUSHES THE LOW E OF LAKE SUPERIOR BY 06Z THURSDAY...THE ECMWF KEEPS IT AS PART OF THE MAIN SYSTEM TO OUR S. THE RESULT IS A COMPLETELY DIFFERENT FCST FOR WEDNESDAY NIGHT...WITH LES OFF THE GFS ON STRONGER NW WINDS...WHILE THE ECMWF SOLUTION KEEPS A WAA SCHEME OVER THE AREA A BIT LONGER. THEY BOTH DO AGREE WITH SOME SORT OF LAKE ENHANCEMENT N OR NW FLOW BY THURSDAY AFTERNOON...ALTHOUGH THE GFS IS APPROX 2C COOLER NEAR THE SFC. LOOK FOR THE CANADIAN AND W COAST SYSTEMS TO DEEPEN AS THEY SINK SSE THURSDAY AND FRIDAY. AT 18Z THURSDAY THE MAIN TROUGH WILL EXTEND FROM THE S LOW OVER S CA UP THROUGH MT INTO S CANADA. A QUICK BURST OF SNOW THURSDAY NIGHT LOOKS TO BE ABOUT IT...EXCEPT FOR SOME LAKE EFFECT/LAKE ENHANCEMENT ON W TO NW WINDS OVER THE KEWEENAW PENINSULA...AND AROUND AND E OF MUNISING THROUGH ABOUT MID MORNING FRIDAY. TOTAL SNOWFALL OF 1-2IN STILL LOOK GOOD. CONFIDENCE REMAINS LOW WITH THIS SYSTEM. THE 12Z NAM DID NOT REALLY BRING ANY OF THE SYNOPTIC MOISTURE INTO UPPER MI...ALTHOUGH THE 18Z VERSION BROUGHT SNOW BACK NW SIMILARLY TO THE GFS. WILL STILL HIGHLIGHT THE POTENTIAL FOR A FEW INCHES OF SNOW LATE THURSDAY AFTERNOON INTO FRIDAY MORNING...MAINLY OVER THE HIGHER TERRAIN NEAR LAKE SUPERIOR. THE NEXT LOW OVER THE ROCKIES SATURDAY WILL EJECT NE SUNDAY...WITH UPPER MI AGAIN ON THE BACK SIDE OF THE LOW. GIVEN THE STRENGTH OF THE SYSTEM...AND SIGNIFICANT HIGH DROPPING IN FROM THE NW SUNDAY THROUGH MONDAY...MUCH COLDER AIR WILL BE ABLE TO SLIDE IN. 850MB TEMPS OF -20 TO -22C WILL BE POSSIBLE. THERE ARE SOME TIMING DIFFERENCES BETWEEN THE GFS AND ECMWF AT THIS PERIOD...BUT THEY ARE CONSISTENT WITH THE COLD AIR. FARTHER OUT...EXPECT STRONG WAA TUESDAY BEHIND THE COLD AIRMASS. WHILE TIMING IS STILL IN QUESTION...SW 40-55KT 850MB WINDS WITH SFC WINDS OF 15-25KTS LOOK LIKELY FOR A 6HR WINDOW BETWEEN 09Z TUESDAY TO 00Z WEDNESDAY. WILL NEED TO MONITOR MODEL TRENDS TO ADD MORE SPECIFICITY AS THE TIME NEARS. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 653 PM EST TUE DEC 17 2013 LAKE EFFECT SNOW WILL CONTINUE AT CMX...BUT CONDITIONS WILL BECOME LESS FAVORABLE FOR LOWER CIGS AND VIS STARTING EARLY WED. AT IWD AND SAW...EXPECT IMPROVEMENT THROUGH THE TAF PERIOD AS A RIDGE OF HIGH PRESSURE MOVES INTO THE AREA. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 343 PM EST TUE DEC 17 2013 EXPECT NW WINDS TO 25-30 KTS THIS EVENING BEHIND A COLD FRONTAL PASSAGE TO DIMINISH AND BACK TO THE SW WITH APPROACH OF A HI PRES RIDGE LATER TONIGHT INTO WED. A VERY CHANGEABLE WEATHER PATTERN WILL THEN DOMINATE THE UPPER GREAT LAKES THE REST OF THE WEEK...WITH HARD TO TIME DISTURBANCES IMPACTING LAKE SUPERIOR. CONFIDENCE IS LOW IN TIMING THESE DISTURBANCES AND ACCOMPANYING WIND SHIFTS...BUT GALES APPEAR UNLIKELY THRU THE FORECAST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...KF AVIATION...TITUS MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
441 PM EST MON DEC 16 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 347 PM EST MON DEC 16 2013 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOWS PERSISTENT NW FLOW ALF OVER THE GREAT LKS BTWN DEEP TROF OVER ERN NAMERICA AND RDG ALONG THE W COAST. VERY COLD CNDN AIR IS IN PLACE OVER THE UPR LKS WITH H5/H85 TEMPS JUST UNDER -30C/ARND -18 OR 19C. DISTURBANCE RESPONSIBLE FOR SN ON SUN HAS NOW PUSHED E INTO QUEBEC...BUT ANOTHER WELL DEFINED CLIPPER SHRTWV JUST E OF LK WINNIPEG EARLY THIS AFTN IS FOLLOWING QUICKLY BEHIND. SHRTWV RDG/DRY MID LVL AIR SHOWN ON THE 12Z APX/GRB RAOBS BROUGHT DRY WX TO UPR MI EARLY THIS AFTN. ALTHOUGH ABSOLUTE MSTR IS LIMITED FOR THE TRAILING DISTURBANCE WITH 12Z PWATS NO HIER THAN 0.25-0.35 INCH IN MN...A BAND OF SN UNDER THE DEEP LYR QVECTOR CNVGC/DPVA/ISENTROPIC ASCENT AHEAD OF THIS FEATURE IS MOVING INTO WRN LK SUP. THE BAND IS RATHER NARROW...BUT VSBYS UNDER THE HEAVIER SN HAVE FALLEN AS LO AS 1/4-3/4 MILES. THIS SN BAND SHIFTED INTO THE WRN COUNTIES BY MID AFTN...AND THE VSBY AT IWD DROPPED TO 1/4SM FOR AN HR. SOME SHSN AND PERHAPS A VORTEX ARE PRESENT OVER NCNTRL LK MI...AND THESE ARE DRIFTING TO THE NNE. ALTHOUGH SOME LIGHT SN LINGERS BACK INTO NW MN BEHIND THIS BAND...VSBYS THERE ARE AOA 3 MILES UNDER THE UPR LVL DRYING SHOWN ON WV IMAGERY/QVECTOR DVGC IN THE WAKE OF THE SHRTWV TROF. IN FACT...THERE HAS BEEN SOME CLRG OVER CENTRAL MN. FARTHER TO THE NW...THERE IS ANOTHER CLIPPER DISTURBANCE DIGGING SEWD IN SASKATCHEWAN. MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE POPS/SN AMNTS AND GOING HEADLINE OVER THE ERN CWA ASSOCIATED WITH APRCHG CLIPPER SHRTWV. FOCUS FOR TUE SHIFTS TO POTENTIAL IMPACT OF SECOND TRAILING DISTURBANCE IN WRN CANADA AS WELL AS THE CHC FOR MORE LK EFFECT SN. LATE THIS AFTN/THRU THIS EVNG...TENDED TO BUMP POPS UP TO CATEGORICAL FOR A FEW HRS AT MOST PLACES W-E THIS AFTN INTO EARLY EVNG WITH PASSAGE OF RATHER NARROW BAND OF SN UNDER AXIS OF H85-5 QVECTOR CNVGC AHEAD OF APRCHG SHRTWV. WITH 2G/KG SPECIFIC HUMIDITY PRESENT NEAR H725 AND A 2-3 HR PERIOD OF HEAVIER SN...EXPECT MOST PLACES WL SEE ARND AN INCH TO PERHAPS 2 INCHES OF SN UNDER THIS HEAVIER BURST. THE ONE EXCEPTION WL BE IN THE SSW FLOW DOWNWIND OF LK MI...WHERE SOME LK ENHANCEMENT WITH H85 TEMPS NEAR -16C/DEEPER MSTR/DYNAMIC FORCING JUSTIFIES GOING WINTER WX ADVY UNTIL PASSAGE OF THE BAND/WSHFT TO THE WSW AFT MIDNGT OVER THE E WL DIMINISH THESE SHSN. FVRBL OMEGA PROFILE WITHIN THE DGZ WL AID IN SN ACCUMS. TO THE W...JUST SOME LINGERING SCT -SHSN WL FOLLOW THE BAND UNDER MID LVL DRYING/QVECTOR DVGC. WHERE THERE IS A BETTER CHC FOR AT LEAST PARTIAL CLRG OVER THE SCNTRL...TENDED TO LOWER FCST MIN TEMPS A BIT WELL INTO THE SINGLE NUMBERS ABV ZERO. LATER TNGT/TUE...MOST OF THE EARLY MRNG SHOULD BE MOCLDY WITH JUST SOME SCT -SHSN/FLURRIES UNDER QVECTOR DVGC IN THE WAKE OF THE DEPARTING CLIPPER. THE SHRTWV NOW OVER SASKATCHEWAN IS FCST TO DIG SEWD AND INTO THE UPR LKS BY 12Z TUE. ALTHOUGH MORE IMPRESSIVE MSTR/DYNAMIC FORCING WL ACCOMPANY ANOTHER SHRTWV PASSING TO THE S IN WI...ARRIVAL OF COLD FNT/DEEPER MSTR ASSOCIATED WITH THE SASKATCHEWAN DISTURBANCE WL BRING A RETURN OF HIER POPS TO MAINLY NW UPR MI ON TUE MRNG. THERE IS SOME DISAGREEMENT AMONG THE MODELS ON HOW MUCH DEEPER MSTR WL ACCOMPANY THIS FROPA. IN GENERAL...THE 12Z NAM/GFS SHOW MORE FVRBL ALIGNMENT BTWN THE DEEPER MSTR AND FROPA TIMING. ALTHOUGH THERE IS SOME POTENTIAL FOR A BRIEF PERIOD OF LK ENHANCED SN WITH H85 TEMPS RISING TO -10C IN THE NARROW THERMAL RDG AHEAD OF THIS FNT...THE NAM/GFS SHOW DEEPER MSTR LINGERING FOR ONLY A 3-6HR PERIOD. AS THE FNT SHIFTS TO THE E...THESE SHSN WL FOLLOW THE BNDRY...WITH THE HIER POPS CLOSER TO LK SUP. BUT WL CARRY LOWER CHC POPS EVEN OVER THE SCENTRAL...WHICH WL BE CLOSER TO THE DYNAMIC FORCING ASSOCIATED WITH SHRTWV PASSING THRU WI. AFTER THE HEAVIER SHSN END OVER THE NW...EXPECT LIGHTER MULTIPLE BAND LES TO IMPACT THE WNW WIND SN BELTS THERE AS COLDER AIR WITH H85 TEMPS FALLING TO ARND -18C BY 00Z WED FOLLOW THE BNDRY. NOT OUT OF THE QUESTION THERE COULD BE ADVY SN FALL OVER THE NW THRU THE DAY...BUT CONCERNS ABOUT TIMING OF DEEPER MSTR LOWER CONFIDENCE ENUF TO HOLD OFF ON A HEADLINE FOR NOW. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 440 PM EST MON DEC 16 2013 EXPECT CONTINUED NW FLOW OVER THE KEWEENAW PENINSULA TUESDAY EVENING WITH ANOTHER 1 TO ALMOST 2IN. A QUICK 1-4IN OF SNOW WILL BE POSSIBLE E OF MUNISING AND N OF NEWBERRY TUESDAY NIGHT. MAY NEED TO HOIST A LES ADVISORY FOR E ALGER AND N PORTIONS OF LUCE COUNTY...WITH THE CONVERGENCE BEHIND THE EXITING LOW. WITH THE 500MB TROUGH SET UP FROM E ONTARIO THROUGH THE LOWER GREAT LAKES...AND A SIZABLE RIDGE DOMINATING THE W HALF OF THE NATION...CHANCES ARE GOOD FOR RIDGING TO MOVE IN FOR MID WEEK. THE RIDGE WILL SLIDE IN AT THE SFC AND ALOFT WEDNESDAY MORNING...AHEAD OF A BROAD AREA OF LOW PRESSURE SET UP FROM SW AND SCENTRAL CANADA THROUGH THE NORTHERN PLAINS. THE WARM WEATHER WILL CONTINUE FOR WEDNESDAY AHEAD OF THIS LOW. ENJOY IT WHILE IT LASTS. WHILE READINGS WILL BE ABOVE WHAT WE HAVE BEEN USE TO /HAVE NOT HAD TEMPS ABOVE 15F AT NWS MQT SINCE THE FIRST 5 DAYS OF DECEMBER/...THEY WILL REMAIN AROUND NORMAL FOR THIS TIME OF YEAR. HIGHS ARE TYPICALLY IN THE MID TO UPPER 20S IN MID DECEMBER. EXPECT THE RIDGE ALOFT TO QUICKLY TURNING TO MORE ZONAL FLOW WEDNESDAY NIGHT WITH BOOKEND TROUGHS OVER THE FAR W AND E SECTIONS OF THE UNITED STATES. BY 00Z THURSDAY THE SFC LOW WILL HAVE MOVED TO THE SE...STRETCHING FROM E CO THROUGH LAKE SUPERIOR. THE N EXTENT OF THE SFC LOW WILL SLOWLY SINK ACROSS LAKE MI AND LOWER MI THROUGH THE DAY THURSDAY...WITH SW FLOW AT 500MB ON THURSDAY IN RESPONSE TO THE LOW DIVING ALONG THE W COAST INTO CA...AND THE NORTHERN LOW PUSHING ACROSS CENTRAL CANADA. A QUICK TENTH OF AN INCH OR SO OF LIQUID FROM THURSDAY AFTERNOON THROUGH THURSDAY EVENING. WITH SNOW RATIOS OF 20-25:1...WILL LIKELY HAVE 1-2IN OF SNOW CWA WIDE BY MIDNIGHT. THE SFC LOW WILL THEN CONSOLIDATE ACROSS LOWER MI AND LAKE HURON AT 12Z FRIDAY...WITH UPPER MI AND THE UPPER GREAT LAKES RETURNING TO OUR TROUGH PATTERN FROM THURSDAY THROUGH NEXT MONDAY. ANOTHER 1-2IN OF SNOW POSSIBLE BEFORE DRYING UP BY LATE FRIDAY MORNING. A BRIEF RIDGE WILL ATTEMPT TO BUILD IN ALOFT SATURDAY OVER THE SE CWA...AS THE NEXT SIGNIFICANT TROUGH PUSHES IN FROM CENTRAL CANADA AND THE PLAINS STATES. A SERIES OF EMBEDDED WAVES WILL CONTINUE TO NEAR FROM THE NW THROUGH AT LEAST MONDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1222 PM EST MON DEC 16 2013 EXPECT VFR CONDITIONS AT TAF ISSUANCE TO DETERIORATE TO IFR W-E AS A BAND OF SN CROSSES UPR MI W-E. THERE MAY BE BRIEF PERIOD OF LIFR CONDITIONS WHEN THE SN IS HEAVIEST. THIS BAND OF SN WL SHIFT E OF SAW AFT 00Z. CONDITIONS IN THE WAKE OF THIS BAND ARE LIKELY TO IMPROVE TO MVFR AND THEN PERHAPS VFR UNDER MID LVL DRYING AT IWD AND SAW...WHERE THE EXPECTED W-SW FLOW IN ITS WAKE WL DOWNSLOPE. CMX IS LIKELY TO HOLD ON TO MVFR CONDITIONS. THE ARRIVAL OF ANOTHER LO PRES TROF/DEEPER MSTR WL BRING A PERIOD OF HEAVIER SHSN/IFR CONDITIONS TO CMX/IWD ON TUE MRNG...BUT DOWNSLOPE NATURE OF THE W WIND INDICATES NO WORSE THAN MVFR WX AT SAW. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 355 PM EST MON DEC 16 2013 S WINDS UP TO 25 TO 30 KTS THIS AFTERNOON AHEAD OF AN APPROACHING LOW PRESSURE TROUGH WILL SHIFT TO THE SW AND DIMINISH OVERNIGHT TO 20 TO 25 KTS AS THE TROUGH SHIFTS TO THE EAST. A STRONGER WEST TO NORTHWEST WIND UP TO 30 KTS WILL DEVELOP ON TUE FOLLOWING THE PASSAGE OF A COLD FRONT. NOT OUT OF THE QUESTION THERE COULD BE A FEW GUSTS TO NEAR GALE FORCE OVER WESTERN LAKE SUPERIOR. NO GALES ARE FORESEEN QUITE YET FROM TUESDAY NIGHT THROUGH SATURDAY...ALTHOUGH A COUPLE OF PERIODS GET CLOSER TO GUSTS OF 25-30KTS. HIGH PRESSURE WILL MOVE INTO THE CENTRAL PLAINS TUESDAY EVENING AND WILL PUSH A BRIEF RIDGE ACROSS LAKE SUPERIOR WEDNESDAY. A TROUGH EXTENDING FROM A BROAD LOW OVER THE ROCKIES AND NORTHERN PLAINS WILL MOVE INTO THE UPPER GREAT LAKES WEDNESDAY NIGHT AND THURSDAY. EXPECT THE LOW TO SINK ACROSS LOWER MICHIGAN BY FRIDAY MORNING. IN THE WAKE OF THE LOW...HIGH PRESSURE OVER THE CENTRAL PLAINS FRIDAY MORNING SHOULD SLOWLY BUILD INTO THE UPPER GREAT LAKES ON FRIDAY...AND REMAIN IN PLACE THROUGH FRIDAY NIGHT. WEAK LOW PRESSURE WILL THEN PUSH ACROSS THE AREA FOR THE START OF THE WEEKEND. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 1 AM EST TUESDAY FOR MIZ007-014. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...KF AVIATION...KC MARINE...KC/KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
355 PM EST MON DEC 16 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 347 PM EST MON DEC 16 2013 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOWS PERSISTENT NW FLOW ALF OVER THE GREAT LKS BTWN DEEP TROF OVER ERN NAMERICA AND RDG ALONG THE W COAST. VERY COLD CNDN AIR IS IN PLACE OVER THE UPR LKS WITH H5/H85 TEMPS JUST UNDER -30C/ARND -18 OR 19C. DISTURBANCE RESPONSIBLE FOR SN ON SUN HAS NOW PUSHED E INTO QUEBEC...BUT ANOTHER WELL DEFINED CLIPPER SHRTWV JUST E OF LK WINNIPEG EARLY THIS AFTN IS FOLLOWING QUICKLY BEHIND. SHRTWV RDG/DRY MID LVL AIR SHOWN ON THE 12Z APX/GRB RAOBS BROUGHT DRY WX TO UPR MI EARLY THIS AFTN. ALTHOUGH ABSOLUTE MSTR IS LIMITED FOR THE TRAILING DISTURBANCE WITH 12Z PWATS NO HIER THAN 0.25-0.35 INCH IN MN...A BAND OF SN UNDER THE DEEP LYR QVECTOR CNVGC/DPVA/ISENTROPIC ASCENT AHEAD OF THIS FEATURE IS MOVING INTO WRN LK SUP. THE BAND IS RATHER NARROW...BUT VSBYS UNDER THE HEAVIER SN HAVE FALLEN AS LO AS 1/4-3/4 MILES. THIS SN BAND SHIFTED INTO THE WRN COUNTIES BY MID AFTN...AND THE VSBY AT IWD DROPPED TO 1/4SM FOR AN HR. SOME SHSN AND PERHAPS A VORTEX ARE PRESENT OVER NCNTRL LK MI...AND THESE ARE DRIFTING TO THE NNE. ALTHOUGH SOME LIGHT SN LINGERS BACK INTO NW MN BEHIND THIS BAND...VSBYS THERE ARE AOA 3 MILES UNDER THE UPR LVL DRYING SHOWN ON WV IMAGERY/QVECTOR DVGC IN THE WAKE OF THE SHRTWV TROF. IN FACT...THERE HAS BEEN SOME CLRG OVER CENTRAL MN. FARTHER TO THE NW...THERE IS ANOTHER CLIPPER DISTURBANCE DIGGING SEWD IN SASKATCHEWAN. MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE POPS/SN AMNTS AND GOING HEADLINE OVER THE ERN CWA ASSOCIATED WITH APRCHG CLIPPER SHRTWV. FOCUS FOR TUE SHIFTS TO POTENTIAL IMPACT OF SECOND TRAILING DISTURBANCE IN WRN CANADA AS WELL AS THE CHC FOR MORE LK EFFECT SN. LATE THIS AFTN/THRU THIS EVNG...TENDED TO BUMP POPS UP TO CATEGORICAL FOR A FEW HRS AT MOST PLACES W-E THIS AFTN INTO EARLY EVNG WITH PASSAGE OF RATHER NARROW BAND OF SN UNDER AXIS OF H85-5 QVECTOR CNVGC AHEAD OF APRCHG SHRTWV. WITH 2G/KG SPECIFIC HUMIDITY PRESENT NEAR H725 AND A 2-3 HR PERIOD OF HEAVIER SN...EXPECT MOST PLACES WL SEE ARND AN INCH TO PERHAPS 2 INCHES OF SN UNDER THIS HEAVIER BURST. THE ONE EXCEPTION WL BE IN THE SSW FLOW DOWNWIND OF LK MI...WHERE SOME LK ENHANCEMENT WITH H85 TEMPS NEAR -16C/DEEPER MSTR/DYNAMIC FORCING JUSTIFIES GOING WINTER WX ADVY UNTIL PASSAGE OF THE BAND/WSHFT TO THE WSW AFT MIDNGT OVER THE E WL DIMINISH THESE SHSN. FVRBL OMEGA PROFILE WITHIN THE DGZ WL AID IN SN ACCUMS. TO THE W...JUST SOME LINGERING SCT -SHSN WL FOLLOW THE BAND UNDER MID LVL DRYING/QVECTOR DVGC. WHERE THERE IS A BETTER CHC FOR AT LEAST PARTIAL CLRG OVER THE SCNTRL...TENDED TO LOWER FCST MIN TEMPS A BIT WELL INTO THE SINGLE NUMBERS ABV ZERO. LATER TNGT/TUE...MOST OF THE EARLY MRNG SHOULD BE MOCLDY WITH JUST SOME SCT -SHSN/FLURRIES UNDER QVECTOR DVGC IN THE WAKE OF THE DEPARTING CLIPPER. THE SHRTWV NOW OVER SASKATCHEWAN IS FCST TO DIG SEWD AND INTO THE UPR LKS BY 12Z TUE. ALTHOUGH MORE IMPRESSIVE MSTR/DYNAMIC FORCING WL ACCOMPANY ANOTHER SHRTWV PASSING TO THE S IN WI...ARRIVAL OF COLD FNT/DEEPER MSTR ASSOCIATED WITH THE SASKATCHEWAN DISTURBANCE WL BRING A RETURN OF HIER POPS TO MAINLY NW UPR MI ON TUE MRNG. THERE IS SOME DISAGREEMENT AMONG THE MODELS ON HOW MUCH DEEPER MSTR WL ACCOMPANY THIS FROPA. IN GENERAL...THE 12Z NAM/GFS SHOW MORE FVRBL ALIGNMENT BTWN THE DEEPER MSTR AND FROPA TIMING. ALTHOUGH THERE IS SOME POTENTIAL FOR A BRIEF PERIOD OF LK ENHANCED SN WITH H85 TEMPS RISING TO -10C IN THE NARROW THERMAL RDG AHEAD OF THIS FNT...THE NAM/GFS SHOW DEEPER MSTR LINGERING FOR ONLY A 3-6HR PERIOD. AS THE FNT SHIFTS TO THE E...THESE SHSN WL FOLLOW THE BNDRY...WITH THE HIER POPS CLOSER TO LK SUP. BUT WL CARRY LOWER CHC POPS EVEN OVER THE SCENTRAL...WHICH WL BE CLOSER TO THE DYNAMIC FORCING ASSOCIATED WITH SHRTWV PASSING THRU WI. AFTER THE HEAVIER SHSN END OVER THE NW...EXPECT LIGHTER MULTIPLE BAND LES TO IMPACT THE WNW WIND SN BELTS THERE AS COLDER AIR WITH H85 TEMPS FALLING TO ARND -18C BY 00Z WED FOLLOW THE BNDRY. NOT OUT OF THE QUESTION THERE COULD BE ADVY SN FALL OVER THE NW THRU THE DAY...BUT CONCERNS ABOUT TIMING OF DEEPER MSTR LOWER CONFIDENCE ENUF TO HOLD OFF ON A HEADLINE FOR NOW. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 400 AM EST MON DEC 16 2013 UPPER TROUGH THAT WILL SWING INTO THE REGION THIS AFTERNOON AND TONIGHT WILL CONTINUE TO INFLUENCE THE UPPER GREAT LAKES REGION ON TUESDAY BEFORE DEPARTING ON TUESDAY NIGHT. AT THE SURFACE...AN ELONGATED TROUGH WILL BE STRETCHING SOUTH FROM HUDSON BAY TO NORTHERN LAKE SUPERIOR AT 12Z TUESDAY AND IT WILL SHIFT EAST THROUGH THE DAY. THIS SHIFT WILL ALLOW FOR COLDER 850MB TEMPERATURES TO SLIDE SOUTHEAST ACROSS UPPER MICHIGAN THROUGH THE DAY (FROM -10C AT 12Z TO -16C AT 00Z WEDNESDAY). ALTHOUGH THERE ARE SOME MINOR DIFFERENCES IN THE MODELS ON THE 850MB TEMPS...THEY ARE FAIRLY CONSISTENT IN THE WIND FIELDS WITH WEST-NORTHWESTERLY FLOW ACROSS THE AREA. MOISTURE ON THE OTHER HAND IS ALL OVER THE MAP AND LEADS TO UNCERTAINTY ON THE SNOWFALL AMOUNTS IN THE WNW SNOW BELTS. THERE SHOULD BE ENOUGH LOW LEVEL MOISTURE FOR SOME LIGHT LAKE EFFECT SNOW TO START TUESDAY MORNING (EVEN THOUGH DELTA-T VALUES ARE A LITTLE MARGINAL). BUT WITH THE 850-700MB MOISTURE LACKING OVER MUCH OF THE AREA AS THE MAIN AREA SLIDES SOUTH OF THE CWA WITH AN EMBEDDED SHORTWAVE...WOULD EXPECT ACCUMULATIONS TO BE LIGHT. MODEL QPF SEEMS TO PICK UP ON THIS IDEA FAIRLY WELL AND ONLY SHOW VERY LIGHT AMOUNTS FOR THE FIRST PART OF THE MORNING. BUT AS THE COLDER AIR AND DEEPER MOISTURE SWEEP IN DURING THE AFTERNOON WITH A WEAK SHORTWAVE...WOULD EXPECT THE INTENSITY OF THE SHOWERS TO INCREASE AS INVERSION HEIGHTS RISE TO 8-10KFT AND LAKE INDUCED CAPES RISE TO 400-500 J/KG. MODEL SOUNDINGS SHOW MUCH OF THE FAVORED LIFT TO BE RIGHT WITHIN THE DGZ...SO WOULD EXPECT SNOW RATIOS TO BE HIGHER END DURING THE AFTERNOON AND FIRST PART OF THE EVENING (MID-UPPER 20S). DID TREND RATIOS UP TOWARDS THAT VALUE...BUT WILL NEED TO KEEP AN EYE ON BL WINDS...BECAUSE THE STRONGER WINDS INDICATED BY THE NAM (NEARING 30KTS) MAY BE ENOUGH TO FRACTURE THE FLAKES AND REDUCE RATIOS. WITH THIS FAVORABLE PERIOD...DID TREND SNOW AMOUNTS UP FOR THE HIGHER TERRAIN FROM ROCKLAND THROUGH THE KEWEENAW (TO 2-4 INCHES) THROUGH THE EVENING HOURS. IN ADDITION...THE SHORTWAVE FORCING...BETTER MOISTURE AND 20-25KT BL WINDS WOULD EXPECT THE SNOW SHOWERS TO HANG TOGETHER FARTHER INLAND THAN PURE LAKE EFFECT AND HAVE CHANCE OF SNOW SHOWERS STRETCHING EAST TO COVER MUCH OF THE WESTERN HALF OF THE U.P. WITH THE DELAYED ARRIVAL OF THE COLDER AIR AND MOISTURE...TRENDED POPS BACK SIGNIFICANTLY OVER THE EAST TO START TUESDAY. WOULD EXPECT A PERIOD OF LITTLE TO NO SNOW INTO THE FIRST PART OF THE AFTERNOON...BEFORE THE COLDER AIR ARRIVES BEHIND THE TROUGH AND INCREASES THE SNOW THROUGH THE EVENING. WHILE THE SNOW IS INCREASING OVER THE EAST...THERE SHOULD BE A DIMINISHING TREND OVER THE WEST DUE TO AN INCOMING HIGH PRESSURE RIDGE. BUFKIT SOUNDINGS ARE SHOWING SIGNIFICANT FALLS TO THE INVERSION HEIGHTS (BELOW 4KFT OVERNIGHT) WITH THE ASSOCIATED SUBSIDENCE. THEREFORE...WILL CONTINUE TO SHOW THE DIMINISHING IDEA WITH THE POPS FIRST OVER THE WEST AND THEN THE EAST LATE IN THE NIGHT. OVERALL...WOULD THINK AREAS EAST OF MUNISING WOULD SEE SNOWFALL AMOUNTS THROUGH TUESDAY NIGHT OF 2-5 INCHES. THE ACTIVE PERIOD OF WEAK SYSTEMS CONTINUES ON WEDNESDAY AS SHORTWAVE QUICKLY SLIDES THROUGH UPPER MICHIGAN. MODELS HAVE TRENDED FARTHER NORTH WITH THIS WAVE AND ASSOCIATED WARM AIR ADVECTION THAN 24HRS AGO...WHICH PUTS THE MAIN AXIS OF THE LIGHT SNOW OVER NORTHERN UPPER MICHIGAN OR LAKE SUPERIOR. A WEAK SURFACE LOW WILL ALSO BE ASSOCIATED WITH THIS WAVE...WITH A TRACK SIMILAR BUT DELAYED FROM THE SNOW AXIS. WILL ATTEMPT TO PROVIDE BETTER TIMING ON THE SNOW/POPS FOR WEDNESDAY AS IT TRAVELS ACROSS THE CWA. WILL KEEP POPS AT CHANCE VALUES AT THIS POINT DUE TO THERE STILL BEING MODEL DIFFERENCES IN THE EXACT LOCATIONS OF BEST SNOW. AMOUNTS SHOULD BE ON THE LIGHT SIDE...WITH A DUSTING TO MAYBE 1-1.5IN. SNOW RATIOS WILL LIKELY BE IN THE UPPER TEENS OR AROUND 20...SINCE THE FORCING IS IN THE DGZ BUT WINDS IN THAT AREA WILL LIKELY FRACTURE THE FLAKES ENOUGH TO KEEP THE RATIOS FROM BEING HIGHER. MODELS DIFFER ON THE LOW LEVEL AND SURFACE FEATURES WEDNESDAY NIGHT INTO THURSDAY AND LEADS TO UNCERTAINTY ON PCPN FORECAST. UPPER GREAT LAKES REGION WILL BE UNDER NEARLY ZONAL FLOW FOR THIS TIME FRAME AS AN UPPER TROUGH BEGINS TO DEVELOP OVER THE WESTERN CONUS. DECENT DIFFERENCES IN THE 00Z GEM/ECMWF AND THE 00Z GFS IN HOW FAR NORTH THE UPPER JET WILL BE...WHICH INFLUENCES THE LOWER LEVEL TEMPERATURE FIELDS. AT THE SURFACE...THE GEM/ECMWF/UKMET HOLD A SURFACE TROUGH OVER THE GREAT LAKES REGION THAT STRETCHES SOUTHWEST TO THE DEVELOPING LOW THAT WILL BE CONTROLLING THE WEATHER FOR THURSDAY NIGHT. GFS ON THE OTHERHAND HAS THE TROUGH FARTHER TO THE SOUTH AND A HIGH PRESSURE RIDGE FROM A HIGH IN SOUTHERN SASKATCHEWAN NOSING OVER LAKE SUPERIOR (OTHER MODELS KEEP IT IN SOUTHERN ONTARIO). THESE LITTLE DIFFERENCES HAVE A FAIRLY SIGNIFICANT AFFECT ON PRECIPITATION MODE WITH 850MB TEMPS AROUND 3C COOLER (-13C OVER LAKE SUPERIOR) AND LOCATIONS (GFS MORE NORTHERLY THAN EAST-NORTHEAST SEEN ON GEM/ECMWF). IN ADDITION...ECMWF DOES SHOW SOME BROAD WARM AIR ADVECTION ALONG THE THERMAL BOUNDARY ON THURSDAY THAT COULD LEAD TO MORE SYNOPTIC SNOW. OVERALL...WILL GO WITH CHANCE POPS ON THURSDAY...MAINLY OVER THE NORTHWEST HALF OF THE CWA AND HAVE SOME HIGHER VALUES OVER THE KEWEENAW WHERE THE SNOW WILL BE MOST LIKELY. DIFFERENCES CONTINUE WITH LOW THAT IS EXPECTED TO MOVE OUT OF THE CENTRAL PLAINS AND THROUGH THE GREAT LAKES REGION. ITS TRACK WILL LARGELY BE DETERMINED ON WHICH MODELS SURFACE TROUGH POSTION IS CORRECT...AS IT WILL TRACK ALONG THAT SAME PATH. THUS...ECMWF/GEM ARE FARTHER NORTH (MOVING THROUGH NORTHERN/CENTRAL LOWER MICHIGAN) AND THE GFS SLIDES IT ACROSS LAKE ERIE. THIS ALSO AFFECTS THERMAL FIELDS...BUT THE U.P. SHOULD SEE IT STAYING AS ALL SNOW EVEN IF THE ECMWF SOLUTION IS CORRECT. WOULD EXPECT AN AREA OF FGEN PRECIPITATION TO MOVE ACROSS UPPER MICHIGAN...BUT LOCATION IS TOO UNCERTAIN AT THIS POINT. ALSO...925-850MB TEMPS SHOULD BE COLD ENOUGH FOR ENHANCEMENT OFF LAKE SUPERIOR WITH THE NORTHERLY WINDS. WILL CONTINUE TO SHOW HIGH CHANCE OR LIKELY POPS FOR THE THURSDAY NIGHT PERIOD AND WOULD THINK A GENERAL 2-4 INCHES OF SNOW WOULD BE EXPECTED IF USING A BLEND OF THE GEM/ECMWF. THE HIGHEST AMOUNTS WOULD BE NEAR LAKE SUPERIOR AND IF THE FGEN AND LAKE ENHANCEMENT LOCATIONS LINE UP TOTALS COULD BE A LITTLE HIGHER. BEHIND THE LOW...WOULD EXPECT A PERIOD OF LAKE EFFECT ON FRIDAY BEFORE QUICKLY DIMINISHING AS HIGH PRESSURE TAKES HOLD. TOO MUCH UNCERTAINTY IN THE MODELS FOR THE WEEKEND WEATHER...BUT NO SIGNIFICANT SNOW IS EXPECTED. WILL LIKELY SEE LAKE EFFECT SNOW NEAR LAKE SUPERIOR ON SUNDAY AS WINDS TURN NORTHERLY AND 850MB TEMPERATURES FALL BEHIND A WEAK LOW. HIGHS THIS WEEKEND (TEENS) LOOK TO CONTINUE THE BELOW NORMAL TREND THIS MONTH. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1222 PM EST MON DEC 16 2013 EXPECT VFR CONDITIONS AT TAF ISSUANCE TO DETERIORATE TO IFR W-E AS A BAND OF SN CROSSES UPR MI W-E. THERE MAY BE BRIEF PERIOD OF LIFR CONDITIONS WHEN THE SN IS HEAVIEST. THIS BAND OF SN WL SHIFT E OF SAW AFT 00Z. CONDITIONS IN THE WAKE OF THIS BAND ARE LIKELY TO IMPROVE TO MVFR AND THEN PERHAPS VFR UNDER MID LVL DRYING AT IWD AND SAW...WHERE THE EXPECTED W-SW FLOW IN ITS WAKE WL DOWNSLOPE. CMX IS LIKELY TO HOLD ON TO MVFR CONDITIONS. THE ARRIVAL OF ANOTHER LO PRES TROF/DEEPER MSTR WL BRING A PERIOD OF HEAVIER SHSN/IFR CONDITIONS TO CMX/IWD ON TUE MRNG...BUT DOWNSLOPE NATURE OF THE W WIND INDICATES NO WORSE THAN MVFR WX AT SAW. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 355 PM EST MON DEC 16 2013 S WINDS UP TO 25 TO 30 KTS THIS AFTERNOON AHEAD OF AN APPROACHING LOW PRESSURE TROUGH WILL SHIFT TO THE SW AND DIMINISH OVERNIGHT TO 20 TO 25 KTS AS THE TROUGH SHIFTS TO THE EAST. A STRONGER WEST TO NORTHWEST WIND UP TO 30 KTS WILL DEVELOP ON TUE FOLLOWING THE PASSAGE OF A COLD FRONT. NOT OUT OF THE QUESTION THERE COULD BE A FEW GUSTS TO NEAR GALE FORCE OVER WESTERN LAKE SUPERIOR. NO GALES ARE FORESEEN QUITE YET FROM TUESDAY NIGHT THROUGH SATURDAY...ALTHOUGH A COUPLE OF PERIODS GET CLOSER TO GUSTS OF 25-30KTS. HIGH PRESSURE WILL MOVE INTO THE CENTRAL PLAINS TUESDAY EVENING AND WILL PUSH A BRIEF RIDGE ACROSS LAKE SUPERIOR WEDNESDAY. A TROUGH EXTENDING FROM A BROAD LOW OVER THE ROCKIES AND NORTHERN PLAINS WILL MOVE INTO THE UPPER GREAT LAKES WEDNESDAY NIGHT AND THURSDAY. EXPECT THE LOW TO SINK ACROSS LOWER MICHIGAN BY FRIDAY MORNING. IN THE WAKE OF THE LOW...HIGH PRESSURE OVER THE CENTRAL PLAINS FRIDAY MORNING SHOULD SLOWLY BUILD INTO THE UPPER GREAT LAKES ON FRIDAY...AND REMAIN IN PLACE THROUGH FRIDAY NIGHT. WEAK LOW PRESSURE WILL THEN PUSH ACROSS THE AREA FOR THE START OF THE WEEKEND. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 1 AM EST TUESDAY FOR MIZ007-014. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...SRF AVIATION...KC MARINE...KC/KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
348 PM EST MON DEC 16 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 347 PM EST MON DEC 16 2013 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOWS PERSISTENT NW FLOW ALF OVER THE GREAT LKS BTWN DEEP TROF OVER ERN NAMERICA AND RDG ALONG THE W COAST. VERY COLD CNDN AIR IS IN PLACE OVER THE UPR LKS WITH H5/H85 TEMPS JUST UNDER -30C/ARND -18 OR 19C. DISTURBANCE RESPONSIBLE FOR SN ON SUN HAS NOW PUSHED E INTO QUEBEC...BUT ANOTHER WELL DEFINED CLIPPER SHRTWV JUST E OF LK WINNIPEG EARLY THIS AFTN IS FOLLOWING QUICKLY BEHIND. SHRTWV RDG/DRY MID LVL AIR SHOWN ON THE 12Z APX/GRB RAOBS BROUGHT DRY WX TO UPR MI EARLY THIS AFTN. ALTHOUGH ABSOLUTE MSTR IS LIMITED FOR THE TRAILING DISTURBANCE WITH 12Z PWATS NO HIER THAN 0.25-0.35 INCH IN MN...A BAND OF SN UNDER THE DEEP LYR QVECTOR CNVGC/DPVA/ISENTROPIC ASCENT AHEAD OF THIS FEATURE IS MOVING INTO WRN LK SUP. THE BAND IS RATHER NARROW...BUT VSBYS UNDER THE HEAVIER SN HAVE FALLEN AS LO AS 1/4-3/4 MILES. THIS SN BAND SHIFTED INTO THE WRN COUNTIES BY MID AFTN...AND THE VSBY AT IWD DROPPED TO 1/4SM FOR AN HR. SOME SHSN AND PERHAPS A VORTEX ARE PRESENT OVER NCNTRL LK MI...AND THESE ARE DRIFTING TO THE NNE. ALTHOUGH SOME LIGHT SN LINGERS BACK INTO NW MN BEHIND THIS BAND...VSBYS THERE ARE AOA 3 MILES UNDER THE UPR LVL DRYING SHOWN ON WV IMAGERY/QVECTOR DVGC IN THE WAKE OF THE SHRTWV TROF. IN FACT...THERE HAS BEEN SOME CLRG OVER CENTRAL MN. FARTHER TO THE NW...THERE IS ANOTHER CLIPPER DISTURBANCE DIGGING SEWD IN SASKATCHEWAN. MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE POPS/SN AMNTS AND GOING HEADLINE OVER THE ERN CWA ASSOCIATED WITH APRCHG CLIPPER SHRTWV. FOCUS FOR TUE SHIFTS TO POTENTIAL IMPACT OF SECOND TRAILING DISTURBANCE IN WRN CANADA AS WELL AS THE CHC FOR MORE LK EFFECT SN. LATE THIS AFTN/THRU THIS EVNG...TENDED TO BUMP POPS UP TO CATEGORICAL FOR A FEW HRS AT MOST PLACES W-E THIS AFTN INTO EARLY EVNG WITH PASSAGE OF RATHER NARROW BAND OF SN UNDER AXIS OF H85-5 QVECTOR CNVGC AHEAD OF APRCHG SHRTWV. WITH 2G/KG SPECIFIC HUMIDITY PRESENT NEAR H725 AND A 2-3 HR PERIOD OF HEAVIER SN...EXPECT MOST PLACES WL SEE ARND AN INCH TO PERHAPS 2 INCHES OF SN UNDER THIS HEAVIER BURST. THE ONE EXCEPTION WL BE IN THE SSW FLOW DOWNWIND OF LK MI...WHERE SOME LK ENHANCEMENT WITH H85 TEMPS NEAR -16C/DEEPER MSTR/DYNAMIC FORCING JUSTIFIES GOING WINTER WX ADVY UNTIL PASSAGE OF THE BAND/WSHFT TO THE WSW AFT MIDNGT OVER THE E WL DIMINISH THESE SHSN. FVRBL OMEGA PROFILE WITHIN THE DGZ WL AID IN SN ACCUMS. TO THE W...JUST SOME LINGERING SCT -SHSN WL FOLLOW THE BAND UNDER MID LVL DRYING/QVECTOR DVGC. WHERE THERE IS A BETTER CHC FOR AT LEAST PARTIAL CLRG OVER THE SCNTRL...TENDED TO LOWER FCST MIN TEMPS A BIT WELL INTO THE SINGLE NUMBERS ABV ZERO. LATER TNGT/TUE...MOST OF THE EARLY MRNG SHOULD BE MOCLDY WITH JUST SOME SCT -SHSN/FLURRIES UNDER QVECTOR DVGC IN THE WAKE OF THE DEPARTING CLIPPER. THE SHRTWV NOW OVER SASKATCHEWAN IS FCST TO DIG SEWD AND INTO THE UPR LKS BY 12Z TUE. ALTHOUGH MORE IMPRESSIVE MSTR/DYNAMIC FORCING WL ACCOMPANY ANOTHER SHRTWV PASSING TO THE S IN WI...ARRIVAL OF COLD FNT/DEEPER MSTR ASSOCIATED WITH THE SASKATCHEWAN DISTURBANCE WL BRING A RETURN OF HIER POPS TO MAINLY NW UPR MI ON TUE MRNG. THERE IS SOME DISAGREEMENT AMONG THE MODELS ON HOW MUCH DEEPER MSTR WL ACCOMPANY THIS FROPA. IN GENERAL...THE 12Z NAM/GFS SHOW MORE FVRBL ALIGNMENT BTWN THE DEEPER MSTR AND FROPA TIMING. ALTHOUGH THERE IS SOME POTENTIAL FOR A BRIEF PERIOD OF LK ENHANCED SN WITH H85 TEMPS RISING TO -10C IN THE NARROW THERMAL RDG AHEAD OF THIS FNT...THE NAM/GFS SHOW DEEPER MSTR LINGERING FOR ONLY A 3-6HR PERIOD. AS THE FNT SHIFTS TO THE E...THESE SHSN WL FOLLOW THE BNDRY...WITH THE HIER POPS CLOSER TO LK SUP. BUT WL CARRY LOWER CHC POPS EVEN OVER THE SCENTRAL...WHICH WL BE CLOSER TO THE DYNAMIC FORCING ASSOCIATED WITH SHRTWV PASSING THRU WI. AFTER THE HEAVIER SHSN END OVER THE NW...EXPECT LIGHTER MULTIPLE BAND LES TO IMPACT THE WNW WIND SN BELTS THERE AS COLDER AIR WITH H85 TEMPS FALLING TO ARND -18C BY 00Z WED FOLLOW THE BNDRY. NOT OUT OF THE QUESTION THERE COULD BE ADVY SN FALL OVER THE NW THRU THE DAY...BUT CONCERNS ABOUT TIMING OF DEEPER MSTR LOWER CONFIDENCE ENUF TO HOLD OFF ON A HEADLINE FOR NOW. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 400 AM EST MON DEC 16 2013 UPPER TROUGH THAT WILL SWING INTO THE REGION THIS AFTERNOON AND TONIGHT WILL CONTINUE TO INFLUENCE THE UPPER GREAT LAKES REGION ON TUESDAY BEFORE DEPARTING ON TUESDAY NIGHT. AT THE SURFACE...AN ELONGATED TROUGH WILL BE STRETCHING SOUTH FROM HUDSON BAY TO NORTHERN LAKE SUPERIOR AT 12Z TUESDAY AND IT WILL SHIFT EAST THROUGH THE DAY. THIS SHIFT WILL ALLOW FOR COLDER 850MB TEMPERATURES TO SLIDE SOUTHEAST ACROSS UPPER MICHIGAN THROUGH THE DAY (FROM -10C AT 12Z TO -16C AT 00Z WEDNESDAY). ALTHOUGH THERE ARE SOME MINOR DIFFERENCES IN THE MODELS ON THE 850MB TEMPS...THEY ARE FAIRLY CONSISTENT IN THE WIND FIELDS WITH WEST-NORTHWESTERLY FLOW ACROSS THE AREA. MOISTURE ON THE OTHER HAND IS ALL OVER THE MAP AND LEADS TO UNCERTAINTY ON THE SNOWFALL AMOUNTS IN THE WNW SNOW BELTS. THERE SHOULD BE ENOUGH LOW LEVEL MOISTURE FOR SOME LIGHT LAKE EFFECT SNOW TO START TUESDAY MORNING (EVEN THOUGH DELTA-T VALUES ARE A LITTLE MARGINAL). BUT WITH THE 850-700MB MOISTURE LACKING OVER MUCH OF THE AREA AS THE MAIN AREA SLIDES SOUTH OF THE CWA WITH AN EMBEDDED SHORTWAVE...WOULD EXPECT ACCUMULATIONS TO BE LIGHT. MODEL QPF SEEMS TO PICK UP ON THIS IDEA FAIRLY WELL AND ONLY SHOW VERY LIGHT AMOUNTS FOR THE FIRST PART OF THE MORNING. BUT AS THE COLDER AIR AND DEEPER MOISTURE SWEEP IN DURING THE AFTERNOON WITH A WEAK SHORTWAVE...WOULD EXPECT THE INTENSITY OF THE SHOWERS TO INCREASE AS INVERSION HEIGHTS RISE TO 8-10KFT AND LAKE INDUCED CAPES RISE TO 400-500 J/KG. MODEL SOUNDINGS SHOW MUCH OF THE FAVORED LIFT TO BE RIGHT WITHIN THE DGZ...SO WOULD EXPECT SNOW RATIOS TO BE HIGHER END DURING THE AFTERNOON AND FIRST PART OF THE EVENING (MID-UPPER 20S). DID TREND RATIOS UP TOWARDS THAT VALUE...BUT WILL NEED TO KEEP AN EYE ON BL WINDS...BECAUSE THE STRONGER WINDS INDICATED BY THE NAM (NEARING 30KTS) MAY BE ENOUGH TO FRACTURE THE FLAKES AND REDUCE RATIOS. WITH THIS FAVORABLE PERIOD...DID TREND SNOW AMOUNTS UP FOR THE HIGHER TERRAIN FROM ROCKLAND THROUGH THE KEWEENAW (TO 2-4 INCHES) THROUGH THE EVENING HOURS. IN ADDITION...THE SHORTWAVE FORCING...BETTER MOISTURE AND 20-25KT BL WINDS WOULD EXPECT THE SNOW SHOWERS TO HANG TOGETHER FARTHER INLAND THAN PURE LAKE EFFECT AND HAVE CHANCE OF SNOW SHOWERS STRETCHING EAST TO COVER MUCH OF THE WESTERN HALF OF THE U.P. WITH THE DELAYED ARRIVAL OF THE COLDER AIR AND MOISTURE...TRENDED POPS BACK SIGNIFICANTLY OVER THE EAST TO START TUESDAY. WOULD EXPECT A PERIOD OF LITTLE TO NO SNOW INTO THE FIRST PART OF THE AFTERNOON...BEFORE THE COLDER AIR ARRIVES BEHIND THE TROUGH AND INCREASES THE SNOW THROUGH THE EVENING. WHILE THE SNOW IS INCREASING OVER THE EAST...THERE SHOULD BE A DIMINISHING TREND OVER THE WEST DUE TO AN INCOMING HIGH PRESSURE RIDGE. BUFKIT SOUNDINGS ARE SHOWING SIGNIFICANT FALLS TO THE INVERSION HEIGHTS (BELOW 4KFT OVERNIGHT) WITH THE ASSOCIATED SUBSIDENCE. THEREFORE...WILL CONTINUE TO SHOW THE DIMINISHING IDEA WITH THE POPS FIRST OVER THE WEST AND THEN THE EAST LATE IN THE NIGHT. OVERALL...WOULD THINK AREAS EAST OF MUNISING WOULD SEE SNOWFALL AMOUNTS THROUGH TUESDAY NIGHT OF 2-5 INCHES. THE ACTIVE PERIOD OF WEAK SYSTEMS CONTINUES ON WEDNESDAY AS SHORTWAVE QUICKLY SLIDES THROUGH UPPER MICHIGAN. MODELS HAVE TRENDED FARTHER NORTH WITH THIS WAVE AND ASSOCIATED WARM AIR ADVECTION THAN 24HRS AGO...WHICH PUTS THE MAIN AXIS OF THE LIGHT SNOW OVER NORTHERN UPPER MICHIGAN OR LAKE SUPERIOR. A WEAK SURFACE LOW WILL ALSO BE ASSOCIATED WITH THIS WAVE...WITH A TRACK SIMILAR BUT DELAYED FROM THE SNOW AXIS. WILL ATTEMPT TO PROVIDE BETTER TIMING ON THE SNOW/POPS FOR WEDNESDAY AS IT TRAVELS ACROSS THE CWA. WILL KEEP POPS AT CHANCE VALUES AT THIS POINT DUE TO THERE STILL BEING MODEL DIFFERENCES IN THE EXACT LOCATIONS OF BEST SNOW. AMOUNTS SHOULD BE ON THE LIGHT SIDE...WITH A DUSTING TO MAYBE 1-1.5IN. SNOW RATIOS WILL LIKELY BE IN THE UPPER TEENS OR AROUND 20...SINCE THE FORCING IS IN THE DGZ BUT WINDS IN THAT AREA WILL LIKELY FRACTURE THE FLAKES ENOUGH TO KEEP THE RATIOS FROM BEING HIGHER. MODELS DIFFER ON THE LOW LEVEL AND SURFACE FEATURES WEDNESDAY NIGHT INTO THURSDAY AND LEADS TO UNCERTAINTY ON PCPN FORECAST. UPPER GREAT LAKES REGION WILL BE UNDER NEARLY ZONAL FLOW FOR THIS TIME FRAME AS AN UPPER TROUGH BEGINS TO DEVELOP OVER THE WESTERN CONUS. DECENT DIFFERENCES IN THE 00Z GEM/ECMWF AND THE 00Z GFS IN HOW FAR NORTH THE UPPER JET WILL BE...WHICH INFLUENCES THE LOWER LEVEL TEMPERATURE FIELDS. AT THE SURFACE...THE GEM/ECMWF/UKMET HOLD A SURFACE TROUGH OVER THE GREAT LAKES REGION THAT STRETCHES SOUTHWEST TO THE DEVELOPING LOW THAT WILL BE CONTROLLING THE WEATHER FOR THURSDAY NIGHT. GFS ON THE OTHERHAND HAS THE TROUGH FARTHER TO THE SOUTH AND A HIGH PRESSURE RIDGE FROM A HIGH IN SOUTHERN SASKATCHEWAN NOSING OVER LAKE SUPERIOR (OTHER MODELS KEEP IT IN SOUTHERN ONTARIO). THESE LITTLE DIFFERENCES HAVE A FAIRLY SIGNIFICANT AFFECT ON PRECIPITATION MODE WITH 850MB TEMPS AROUND 3C COOLER (-13C OVER LAKE SUPERIOR) AND LOCATIONS (GFS MORE NORTHERLY THAN EAST-NORTHEAST SEEN ON GEM/ECMWF). IN ADDITION...ECMWF DOES SHOW SOME BROAD WARM AIR ADVECTION ALONG THE THERMAL BOUNDARY ON THURSDAY THAT COULD LEAD TO MORE SYNOPTIC SNOW. OVERALL...WILL GO WITH CHANCE POPS ON THURSDAY...MAINLY OVER THE NORTHWEST HALF OF THE CWA AND HAVE SOME HIGHER VALUES OVER THE KEWEENAW WHERE THE SNOW WILL BE MOST LIKELY. DIFFERENCES CONTINUE WITH LOW THAT IS EXPECTED TO MOVE OUT OF THE CENTRAL PLAINS AND THROUGH THE GREAT LAKES REGION. ITS TRACK WILL LARGELY BE DETERMINED ON WHICH MODELS SURFACE TROUGH POSTION IS CORRECT...AS IT WILL TRACK ALONG THAT SAME PATH. THUS...ECMWF/GEM ARE FARTHER NORTH (MOVING THROUGH NORTHERN/CENTRAL LOWER MICHIGAN) AND THE GFS SLIDES IT ACROSS LAKE ERIE. THIS ALSO AFFECTS THERMAL FIELDS...BUT THE U.P. SHOULD SEE IT STAYING AS ALL SNOW EVEN IF THE ECMWF SOLUTION IS CORRECT. WOULD EXPECT AN AREA OF FGEN PRECIPITATION TO MOVE ACROSS UPPER MICHIGAN...BUT LOCATION IS TOO UNCERTAIN AT THIS POINT. ALSO...925-850MB TEMPS SHOULD BE COLD ENOUGH FOR ENHANCEMENT OFF LAKE SUPERIOR WITH THE NORTHERLY WINDS. WILL CONTINUE TO SHOW HIGH CHANCE OR LIKELY POPS FOR THE THURSDAY NIGHT PERIOD AND WOULD THINK A GENERAL 2-4 INCHES OF SNOW WOULD BE EXPECTED IF USING A BLEND OF THE GEM/ECMWF. THE HIGHEST AMOUNTS WOULD BE NEAR LAKE SUPERIOR AND IF THE FGEN AND LAKE ENHANCEMENT LOCATIONS LINE UP TOTALS COULD BE A LITTLE HIGHER. BEHIND THE LOW...WOULD EXPECT A PERIOD OF LAKE EFFECT ON FRIDAY BEFORE QUICKLY DIMINISHING AS HIGH PRESSURE TAKES HOLD. TOO MUCH UNCERTAINTY IN THE MODELS FOR THE WEEKEND WEATHER...BUT NO SIGNIFICANT SNOW IS EXPECTED. WILL LIKELY SEE LAKE EFFECT SNOW NEAR LAKE SUPERIOR ON SUNDAY AS WINDS TURN NORTHERLY AND 850MB TEMPERATURES FALL BEHIND A WEAK LOW. HIGHS THIS WEEKEND (TEENS) LOOK TO CONTINUE THE BELOW NORMAL TREND THIS MONTH. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1222 PM EST MON DEC 16 2013 EXPECT VFR CONDITIONS AT TAF ISSUANCE TO DETERIORATE TO IFR W-E AS A BAND OF SN CROSSES UPR MI W-E. THERE MAY BE BRIEF PERIOD OF LIFR CONDITIONS WHEN THE SN IS HEAVIEST. THIS BAND OF SN WL SHIFT E OF SAW AFT 00Z. CONDITIONS IN THE WAKE OF THIS BAND ARE LIKELY TO IMPROVE TO MVFR AND THEN PERHAPS VFR UNDER MID LVL DRYING AT IWD AND SAW...WHERE THE EXPECTED W-SW FLOW IN ITS WAKE WL DOWNSLOPE. CMX IS LIKELY TO HOLD ON TO MVFR CONDITIONS. THE ARRIVAL OF ANOTHER LO PRES TROF/DEEPER MSTR WL BRING A PERIOD OF HEAVIER SHSN/IFR CONDITIONS TO CMX/IWD ON TUE MRNG...BUT DOWNSLOPE NATURE OF THE W WIND INDICATES NO WORSE THAN MVFR WX AT SAW. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 449 AM EST MON DEC 16 2013 WITH A HIGH PRESSURE RIDGE OVER THE AREA...GALES HAVE ENDED. NEXT CHANCE FOR STRONGER WINDS WOULD BE TUESDAY AFTERNOON AS THERE COULD BE SOME GALE FORCE GUSTS TO 35 KNOTS ACROSS THE WEST HALF OF LAKE SUPERIOR WITH NORTHWEST WINDS AND COLDER AIR COMING ACROSS LAKE SUPERIOR. OTHERWISE...NO GALES ARE SEEN AS NO STRONG PRESSURE SYSTEMS STAY AWAY FROM THE AREA. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 1 AM EST TUESDAY FOR MIZ007-014. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...SRF AVIATION...KC MARINE...07
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
324 AM CST Mon Dec 16 2013 .SHORT TERM: (Through Tonight) Issued at 1233 AM CST Mon Dec 16 2013 Clipper continues to move esewd thru the region with the sfc fnt stretched thru the area near I-70. A lot of uncertainty remains as to where any fg develops, if any, or if mainly st will develop. Areas S of the fnt may continue to see enuf mixing to prevent any fg development despite the additional moisture due to sn melt. Clouds are expected to linger thru much of the day across the nrn half of the CWA. Have trended twd the warmer guidance across the region. May still need to raise temps across the srn counties as some areas further SW have already reached the lower to mid 40s. With mixing expected to continue overnight and at least high clouds spreading over the region, have trended twd the warmer guidance thru tonight as well. Tilly .LONG TERM: (Tuesday through Sunday) Issued at 242 AM CST Mon Dec 16 2013 (Tuesday through Wednesday) With no precip expected thru this period, focus will be warming temps. Mdls are in good agreement regarding mass fields. Prev forecast still appears to be largely on track and have therefore made only minor changes. In general, continued trend twd warmer guidance. With strong WAA over the region on Wed, going forecast may not be warm enuf as thermal ridge pushes thru the region. Believe mdls are holding on to the snow field too long into the forecast period. One factor that may hinder this strong warming is development of fg/st. (Thursday through Sunday) Focus quickly turns to the systems to impact the area late this week and thru the weekend. Mdls are coming into better agreement, but differences remain that would be the difference in ra turning to sn or resulting in fzra. Timing and placement differences exist over the weekend as another system pulls newd thru the region. The ECMWF brings the sfc low further nwd suggesting ra, while the GFS keeps the system further S suggesting mostly a sn event. Due to uncertainty regarding placement and timing, have kept the going forecast as is except for changes in POPs to account for at least an agreement or possibility of precip. Will make adjustments as needed as mdls come into better agreement. Tilly && .AVIATION: (For the 06z TAFs through 06z Monday Night) Issued at 1138 PM CST Sun Dec 15 2013 BUFKIT soundings from the RAP still show light winds and a strong surface-based inversion along with nearly saturated conditions at the lowest levels. It still looks like a period of IFR to MVFR fog will develop over the next 6 hours, then lift into stratus during the morning hours, but confidence remains low with respect to the timing. Stratus is likely to linger for most of the day due to poor mixing and low sun angle, especially at KUIN. Conditions should improve during the day, but fog/stratus is possible again on Monday night due to the additional moisture provided by melting snow. Specifics for KSTL: A boundary is wavering back and forth across KSTL, causing fluctuations in the temperature and dew point, which in turn is affecting the fog potential. It still looks like a period of IFR or MVFR fog will develop over the next 6 hours, then lift into stratus during the morning hours. Confidence in the timing of fog remains low. Conditions should improve during the day, however fog/stratus is possible again on Monday night due to the additional moisture provided by melting snow. Kanofsky && .PRELIMINARY POINT TEMPS/POPS: Saint Louis 42 28 45 29 / 5 0 0 0 Quincy 32 22 38 22 / 5 0 0 0 Columbia 45 27 46 28 / 5 0 0 0 Jefferson City 46 27 48 28 / 5 0 0 0 Salem 40 27 41 26 / 10 0 0 0 Farmington 47 28 48 28 / 5 0 0 0 && .LSX WATCHES/WARNINGS/ADVISORIES: MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
109 AM CST Mon Dec 16 2013 .SHORT TERM: (Through Tonight) Issued at 1233 AM CST Mon Dec 16 2013 Clipper continues to move esewd thru the region with the sfc fnt stretched thru the area near I-70. A lot of uncertainty remains as to where any fg develops, if any, or if mainly st will develop. Areas S of the fnt may continue to see enuf mixing to prevent any fg development despite the additional moisture due to sn melt. Clouds are expected to linger thru much of the day across the nrn half of the CWA. Have trended twd the warmer guidance across the region. May still need to raise temps across the srn counties as some areas further SW have already reached the lower to mid 40s. With mixing expected to continue overnight and at least high clouds spreading over the region, have trended twd the warmer guidance thru tonight as well. Tilly .LONG TERM: (Monday Night through Next Sunday) Issued at 259 PM CST Sun Dec 15 2013 Despite another weak and ill-defined cold front passing though the area on Tuesday, the temperatures should moderate some. The real moderation however will begin to unfold on Tuesday night as the surface high retreats and low level WAA gets underway. Strong WAA will be in full swing on Wednesday as low level flow becomes south/southwesterly and the upper flow transitions to quasi-zonal. This should be a big snow melter with highs in the upper 40s-middle 50s. The extended portion of the forecast, especially towards the weekend, is marked by considerable uncertainty. A big pattern change will continue to evolve with considerable amplification from the central Pacific across the CONUS. The main feature will be the development of a split flow regime with a deep long wave positively tilted trof in the western U.S. and upper low in the southwest. This trof develops in response to the absorption of an upper low currently in the southeast Pacific near 27N/134W and short waves digging southward out of the Gulf of AK along the west coast. The northern stream will serve to bring a cold front through the area Thursday night/early Friday accompanied by a chance of rain and possibly some rain/snow mix in the wake. However the northern stream is sharper on the GFS and it also leaves the upper low spinning in the vicinity of northern Baja CA. This solution would suggest limited post-frontal precipitation with high pressure building into the Mid MS Valley late Friday and then additional waves in the northern stream reinforcing the high pressure and essentially keeping precipitation south of the area. Alternatively the ECMWF develops an overrunning scenario Saturday into Sunday and potential for a winter mess. There is no scientific basis at this point in time to suggest one solution is vastly better than another and the models will continue to change multiple times in the details in the coming week. Given the forecast large scale pattern changes and vastly differing model solutions and resultant low confidence, the best approach at this time is more of an ensemblistic approach with some mixed flavor. Glass && .AVIATION: (For the 06z TAFs through 06z Monday Night) Issued at 1138 PM CST Sun Dec 15 2013 BUFKIT soundings from the RAP still show light winds and a strong surface-based inversion along with nearly saturated conditions at the lowest levels. It still looks like a period of IFR to MVFR fog will develop over the next 6 hours, then lift into stratus during the morning hours, but confidence remains low with respect to the timing. Stratus is likely to linger for most of the day due to poor mixing and low sun angle, especially at KUIN. Conditions should improve during the day, but fog/stratus is possible again on Monday night due to the additional moisture provided by melting snow. Specifics for KSTL: A boundary is wavering back and forth across KSTL, causing fluctuations in the temperature and dew point, which in turn is affecting the fog potential. It still looks like a period of IFR or MVFR fog will develop over the next 6 hours, then lift into stratus during the morning hours. Confidence in the timing of fog remains low. Conditions should improve during the day, however fog/stratus is possible again on Monday night due to the additional moisture provided by melting snow. Kanofsky && .PRELIMINARY POINT TEMPS/POPS: Saint Louis 28 44 28 54 / 0 0 0 0 Quincy 22 37 21 48 / 0 0 0 0 Columbia 27 45 27 56 / 0 0 0 0 Jefferson City 27 47 27 57 / 0 0 0 0 Salem 27 40 25 48 / 0 0 0 0 Farmington 28 47 27 52 / 0 0 0 0 && .LSX WATCHES/WARNINGS/ADVISORIES: MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1159 PM CST Sun Dec 15 2013 .UPDATE: Issued at 849 PM CST Sun Dec 15 2013 A well-defined baroclinic zone reaching from the Dakotas southeastward through northwest Missouri has extended through east central Missouri and into southwest Illinois this evening, and makes for a bit of a tricky forecast overnight tonight. Despite uncertainties associated with this baroclinic zone, feel that overall, the going forecast this evening remains on track. Pockets of light snow have continued over Iowa and Illinois in response to a vort max moving within the northwest flow aloft, and while much of the activity looks to remain north of the area, still cannot rule out some light freezing rain or light snow, mainly over the northern periphery of the forecast area. The most recent run of the HRRR supports this, indicating spotty precipitation over the next few hours over northeast Missouri and west central Illinois. Near and south of the baroclinic zone, dewpoints this evening are still hanging in the middle to upper 20s, thus feel that the mention of fog for this area continues to be warranted tonight as temperatures fall. Beyond adjusting near term trends based on current observations, no major changes have been warranted this evening. JP && .SHORT TERM: (Tonight through Monday) Issued at 259 PM CST Sun Dec 15 2013 Lots of caveats to the forecast for tonight leading to low confidence in some of the details. A strong surface front currently extends from western SD through central NE and northeast KS across northern MO into west central IL. The models are in decent agreement that a surface low pressure wave will track southeastward along the front from the central Plains into southern IL tonight with the front sagging southward in its wake. This surface low will be in response to a weak elongated short wave/vort max migrating southeastward within the NW flow aloft. The large scale forcing and strongest low level baroclinicity/frontogenesis will reside to the north of the forecast area from Iowa thru north central IL into southeast IN and this is where the greatest threat of snow should reside. Along the far southern periphery of this zone which encompasses a zone from around Edina to Quincy to White Hall to Nokomis, the RAP suggests there could be a brief shot of decent ascent. It also has some very light QPF within this zone and the last few available runs of the HRRR showed some spotty precipitation. The overall low level flow regime is characterized south of the aforementioned front and above the boundary layer by warm air advection. This WAA while also contributing to lift has warmed the atmosphere and soundings suggest any precipitation could teeter between light freezing rain or light snow. I have added some low pops to account for this probability and it will bear close watching on the evening shift. Further south snow melt has contributed to low level moistening and some of the guidance suggests fog and stratus will develop. The 12z run of the NAM even went as far as developing freezing drizzle. The boundary layer is where all the models have the poorest time resolving, thus my confidence is limited, but given the current surface dew points are now close to the forecast mins I have opted to included a mention of fog in the forecast. If stratus and fog are widespread on Monday morning, then the trend should be for this to erode/dissipate as the morning progresses and weak low level WAA kicks in. If the stratus/fog or clouds are at a minimum then my forecast highs are likely too cool. Glass .LONG TERM: (Monday Night through Next Sunday) Issued at 259 PM CST Sun Dec 15 2013 Despite another weak and ill-defined cold front passing though the area on Tuesday, the temperatures should moderate some. The real moderation however will begin to unfold on Tuesday night as the surface high retreats and low level WAA gets underway. Strong WAA will be in full swing on Wednesday as low level flow becomes south/southwesterly and the upper flow transitions to quasi-zonal. This should be a big snow melter with highs in the upper 40s-middle 50s. The extended portion of the forecast, especially towards the weekend, is marked by considerable uncertainty. A big pattern change will continue to evolve with considerable amplification from the central Pacific across the CONUS. The main feature will be the development of a split flow regime with a deep long wave positively tilted trof in the western U.S. and upper low in the southwest. This trof develops in response to the absorption of an upper low currently in the southeast Pacific near 27N/134W and short waves digging southward out of the Gulf of AK along the west coast. The northern stream will serve to bring a cold front through the area Thursday night/early Friday accompanied by a chance of rain and possibly some rain/snow mix in the wake. However the northern stream is sharper on the GFS and it also leaves the upper low spinning in the vicinity of northern Baja CA. This solution would suggest limited post-frontal precipitation with high pressure building into the Mid MS Valley late Friday and then additional waves in the northern stream reinforcing the high pressure and essentially keeping precipitation south of the area. Alternatively the ECMWF develops an overrunning scenario Saturday into Sunday and potential for a winter mess. There is no scientific basis at this point in time to suggest one solution is vastly better than another and the models will continue to change multiple times in the details in the coming week. Given the forecast large scale pattern changes and vastly differing model solutions and resultant low confidence, the best approach at this time is more of an ensemblistic approach with some mixed flavor. Glass && .AVIATION: (For the 06z TAFs through 06z Monday Night) Issued at 1138 PM CST Sun Dec 15 2013 BUFKIT soundings from the RAP still show light winds and a strong surface-based inversion along with nearly saturated conditions at the lowest levels. It still looks like a period of IFR to MVFR fog will develop over the next 6 hours, then lift into stratus during the morning hours, but confidence remains low with respect to the timing. Stratus is likely to linger for most of the day due to poor mixing and low sun angle, especially at KUIN. Conditions should improve during the day, but fog/stratus is possible again on Monday night due to the additional moisture provided by melting snow. Specifics for KSTL: A boundary is wavering back and forth across KSTL, causing fluctuations in the temperature and dew point, which in turn is affecting the fog potential. It still looks like a period of IFR or MVFR fog will develop over the next 6 hours, then lift into stratus during the morning hours. Confidence in the timing of fog remains low. Conditions should improve during the day, however fog/stratus is possible again on Monday night due to the additional moisture provided by melting snow. Kanofsky && .LSX WATCHES/WARNINGS/ADVISORIES: MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS GLASGOW MT
904 PM MST TUE DEC 17 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH THURSDAY... UPDATE...HAVE SOME CONCERN FOR FREEZING SPRINKLES ACROSS AREAS NORTH OF THE MISSOURI RIVER. VERY LIGHT PCPN SHOWING UP ON THE KTFX RADAR THIS EVENING OVER BLAINE COUNTY. FOR NOW WILL NOT JUMP ON IT. HOWEVER MAY HAVE TO DO A QUICK UPDATE LATER IF THE TREND CONTINUES AS THE RUC MODEL SUGGESTS. OTHERWISE ATTEMPTED TO ADJUST OVERNIGHT TEMPERATURES WITH A WIDE RANGE DUE TO ELEVATION TEMPERATURE WISE ACROSS THE FORECAST AREA. PROTON WARM AIR ALOFT AND SHALLOW INVERSION WILL PERSIST OVERNIGHT WITH WEST TO SOUTHWEST FLOW AHEAD OF THE COLD FRONT. THIS STRONG FLOW WILL KEEP INVERSION FROM DEEPENING TOO MUCH UNTIL THE COLD FRONT DROPS OUT OF CANADA. FRONT IS EXPECTED INTO NORTHEAST MONTANA DURING THE MORNING...SLIDING INTO SOUTHERN MONTANA IN THE AFTERNOON. MOISTURE MOVES INTO THE REGION WITH THE COLD AIR...WITH SOME CHANCE OF FREEZING RAIN IN THE MORNING BEFORE THE AIRMASS COOLS ENOUGH FOR SNOW. SHORTWAVE PUSHING INTO WESTERN CANADA WILL FOCUS THE BEST LIFT ACROSS THE SOUTHWEST HALF OF THE STATE...LEAVING MUCH OF NORTHEAST MONTANA INFLUENCED BY THE DRIER BUT COLD HIGH PRESSURE. BEST CHANCE OF SNOW IS EXPECTED IN THE BETTER UPSLOPE AREAS IN THE SOUTHWEST BEGINNING LATE WEDNESDAY AFTERNOON...THEN SPREADING INTO THE YELLOWSTONE VALLEY WEDNESDAY NIGHT BEFORE TAPERING OFF THURSDAY. BLOWING SNOW NOT EXPECTED TO BE EXTENSIVE WITH WINDS MOSTLY BELOW 20 MPH WHERE THE SNOW WILL OCCUR. THE CANADIAN HIGH PRESSURE MOVES OVER NORTHEAST MONTANA LATE THURSDAY THEN INTO THE DAKOTAS. COLDEST AIR IS OVER THE REGION THURSDAY WITH 850MB TEMPERATURES AROUND MINUS 18...RESULTING IN SUBZERO SURFACE TEMPERATURES. MAY HAVE ENOUGH WIND AS THE HIGH PUSHES SOUTH FOR WIND CHILL CONCERNS ON WEDNESDAY NIGHT. EBERT .LONG TERM...THURSDAY NIGHT THROUGH TUESDAY... THE EXTENDED PERIOD BEGINS THURSDAY EVENING WITH NORTHEAST MONTANA UNDER A NORTHWESTERLY FLOW ALOFT AND A SPLIT-WAVE TROUGH MOVING THROUGH THE REGION. TO THE NORTH NEAR HUDSON BAY IS A CLOSED UPPER LOW WITH ARCTIC TEMPERATURES. TO THE SOUTH IS THE TROUGH EXTENSION TAKING A WINTER STORM EAST TOWARDS THE GREAT LAKES REGION. THE LOCAL AREA WITH A RETREATING COLD FRONT WILL SEE 850MB TEMPERATURES OF AROUND -10C. SO EXPECT SINGLE TO DOUBLE DIGITS BELOW 0F BY FRIDAY MORNING...AND BELOW NORMAL HIGHS ON FRIDAY. ANOTHER ARCTIC COLD FRONT SURGES SOUTH INTO MONTANA ON THE WEEKEND FOR COLDER TEMPERATURES. THE TIMING AND LOCATION FOR SNOW IS NOT YET SETTLED BETWEEN THE GFS AND EC. BUT ABOVE CLIMO POPS SEEMS REASONABLE FOR NOW. SO WENT AHEAD LOWERED TEMPERATURES AND RAISED POPS A BIT. THEN MODELS SHOW ANOTHER WAVE OF VARYING STRENGTH...DEPENDING ON MODEL...EARLY NEXT WEEK...WHICH COULD BRING MORE SNOW AND LOWERING TEMPERATURES. SCT PREVIOUS DISCUSSION... NORTHEAST MONTANA WILL BE UNDER THE INFLUENCE OF SURFACE HIGH PRESSURE ON THURSDAY NIGHT. MODELS DEPICT 850MB TEMPERATURES GRADUALLY MODIFYING OVERNIGHT AS THE HIGH SLIDES EASTWARD INTO THE DAKOTAS. HOWEVER...THE LATEST ECMWF FOR INSTANCE STILL SHOWS A RANGE OF 850MB TEMPERATURES AROUND -10C ON THE BORDER BETWEEN THE CWA AND NORTH DAKOTA...RANGING TO ABOUT -4C NEAR WINNETT. OVERALL...EXPECT A COLD MORNING ON FRIDAY WITH LOWS DROPPING BELOW ZERO FOR A LARGE PORTION OF THE REGION. STILL EXPECT DRY CONDITIONS PERSISTING INTO FRIDAY GIVEN THE INFLUENCE OF HIGH PRESSURE. UPPER LEVEL SHORTWAVES RIDING ON NORTHWEST FLOW ALOFT WILL AFFECT THE REGION AS EARLY AS FRIDAY NIGHT...LINGERING INTO SATURDAY. THE 00Z RUNS OF THE GFS AND ECMWF SHOW GOOD CONSENSUS ON QPF PLACEMENT IN THE WESTERN ZONES...BUT THE ECWMF HAS THE PRECIPITATION MAKING IT A BIT FURTHER EASTWARD. MOISTURE AT THIS TIME APPEARS LIMITED...ECMWF AND GFS SHOW ABOUT 1-1.5 G/KG 700MB MIXING RATIOS ACROSS MUCH OF THE CWA FRIDAY NIGHT...BUT AS HIGH AS ABOUT 2.0 G/KG IN SOUTHWEST PHILLIPS/PETROLEUM COUNTIES. DO NOT SEE MUCH JET ENHANCEMENT AT THIS TIME AND UPPER LEVEL SYSTEM IS NOT ALL THAT IMPRESSIVE SO PVA SHOULD BE WEAK AT BEST. SURFACE BOUNDARY PUSHING INTO THE CWA FROM THE NORTHEAST ON SATURDAY COULD ENHANCE LOW LEVEL CONVERGENCE AND PROMOTE LIFT. THAT IN CONJUNCTION WITH THE UPPER LEVEL SUPPORT FROM SHORTWAVE ENERGY PROPAGATING THROUGH THE FLOW MAY COMBINE WITH AVAILABLE MOISTURE TO SQUEEZE OUT SOME LIGHT SNOW...BUT WOULD NOT THINK MOST PLACES WOULD SEE MUCH MORE THAN A COATING TO AN INCH OF SNOW. HIGHEST CONFIDENCE ON ACCUMULATIONS AT THIS POINT APPEAR TO BE IN THE SOUTHWESTERN ZONES...CO-LOCATED WITH THAT HIGHER MID LEVEL MIXING RATIO AIR WITHIN THE DENDRITIC GROWTH ZONE. WEAK UPPER RIDGING MAY BECOME ESTABLISHED OVER THE NORTHERN PLAINS EARLY NEXT WEEK...SO WILL ALLOW FOR A MODERATING TREND IN TEMPERATURES. ENSEMBLE SPREAD IN THE MODELS INCREASES THIS FAR OUT INTO THE EXTENDED AND PRECIPITATION CHANCES WILL HINGE ON TIMING/TRACK OF SHORTWAVES THAT ARE NOT YET PREDICTABLE WITH MUCH CONFIDENCE. FEEL GOOD ABOUT INTRODUCING NEAR CLIMO/SLIGHT CHANCE POPS INTO THE GRIDS THROUGH MUCH OF THE LATTER PORTIONS OF THE EXTENDED. MALIAWCO && .AVIATION... VFR CONDITIONS WILL CONTINUE INTO TONIGHT. WINDS WILL BE LIGHT AND VARIABLE OVERNIGHT. LIGHT SNOW WILL BE POSSIBLE ON WEDNESDAY WITH THE PASSAGE OF AN ARCTIC COLD FRONT. MALIAWCO && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS BILLINGS MT
330 PM MST MON DEC 16 2013 .SHORT TERM...VALID FOR TUE AND WED... MILD AND WINDY WEATHER WILL CONTINUE THROUGH WED BENEATH NORTHWEST FLOW ALOFT...BUT A SHORT WAVE TROUGH WILL THEN SEND AN ARCTIC COLD FRONT SOUTH THROUGH THE REGION WITH SNOW BEGINNING WED NIGHT. TONIGHT...WE HAVE LINGERED SOME LIKELY POPS THROUGH THE EVENING IN THE BAKER AREA...LARGELY BASED ON RECENT RAP SIMULATIONS WHICH ARE ABOUT THE ONLY GUIDANCE CAPTURING ONGOING SNOW OVER THAT AREA. THE SNOW /WHICH WE DID NOT EXPECT TO THIS MAGNITUDE/ APPEARS DRIVEN BY MID-LEVEL FRONTOGENESIS...WHICH SHOULD ONLY SLOWLY WANE DURING THE LATE AFTERNOON AND EVENING. OTHERWISE...WINDS WILL INCREASE BEFORE DAYBREAK AGAIN IN THE LIVINGSTON AND NYE AREAS AS SUBSTANTIAL LEE- SIDE SURFACE PRESSURE FALLS TAKE SHAPE FROM NORTH CENTRAL MT UP TO CENTRAL ALBERTA. WE THUS BEGAN A WIND ADVISORY AT 09 UTC FOR THOSE LOCATIONS. FINALLY...WE GENERALLY HELD LOWS A BIT WARMER THAN WHAT GUIDANCE WOULD SUGGEST IN MOST PLACES TONIGHT SINCE DEWPOINTS THIS AFTERNOON HAVE MAINLY STAYED IN THE 20S F. OUR CONFIDENCE IS LOWER THAN NORMAL THOUGH. ONE EXCEPTION TO THIS METHODOLOGY WAS AT BAKER WHERE FRESH SNOW COULD ALLOW TEMPERATURES TO FALL QUICKLY. TUE...A STRONG LOW-LEVEL PRESSURE GRADIENT WILL CONTINUE FOR SOUTH CENTRAL MT AND CONTINUE TO BE AIDED BY ISALLOBARIC FORCING WITH AN AXIS OF 5 HPA/3 HOUR SURFACE PRESSURE FALLS NORTHEAST OF THE LOCAL AREA. THE MAGNITUDE OF MID-LEVEL STABILITY AND 700-HPA WIND SPEEDS OF 50 KT OVER LIVINGSTON BODE WELL FOR ADVISORY-LEVEL WINDS THANKS TO A 15-20 HPA SURFACE GRADIENT BETWEEN IDAHO FALLS AND LEWISTOWN. DOWNSTREAM...MID-LEVEL WINDS ARE CLOSER TO 60 KT FOR HARLOWTON AND BIG TIMBER...AND LOW-LEVEL LAPSE RATES ARE STEEP ENOUGH TO SUPPORT 60 MPH GUSTS IN THOSE AREAS. THUS...WE ISSUED A WIND ADVISORY OVER NORTHERN SWEET GRASS COUNTY AND A HIGH WIND WATCH ACROSS SOUTHERN WHEATLAND COUNTY /WHERE WARNING CRITERIA IS LOWER/ BEGINNING AT 13 UTC TUE. AN IN-HOUSE STATISTICAL METHOD FOR HIGH WINDS IN SOUTHERN WHEATLAND COUNTY ALSO SUPPORTS 60-65 MPH GUSTS AT HARLOWTON. HIGHS WILL BE MILD AGAIN TUE...WITH 50+ F READINGS IN SOUTH CENTRAL MT. TUE NIGHT...STRONG WINDS WILL CONTINUE IN SOUTH CENTRAL MT...SO WE KEPT HEADLINES GOING. A WELL-MIXED BOUNDARY LAYER MAY KEEP LOWS ON THE WARM SIDE...EVEN ON THE RIDGETOPS OF SOUTHEASTERN MT. BY WED...THE LOW-LEVEL PRESSURE GRADIENT WILL BE RELAXING...SO THE WINDS SHOULD BEGIN DECREASING DURING THE MORNING. ANOTHER MILD DAY IS IN STORE...AND MUCH LIKE PRIOR DAYS IT/S POSSIBLE THAT GUIDANCE WILL HAVE A COLD BIAS GIVEN THE RAPIDLY MELTING SNOW FIELD. ON WED NIGHT...WE HAVE HIGH CONFIDENCE IN AN ARCTIC COLD FRONT PUSHING TO THE SOUTH ACROSS THE AREA...WITH WIDESPREAD SNOW DEVELOPING BEHIND THE BOUNDARY PER WELL-CLUSTERED 12 UTC MODEL SOLUTIONS. QG FORCING ALOFT AND LOW-LEVEL UPSLOPE STRONGLY SUPPORTS A FEW INCHES OF SNOW OVER MUCH OF THE AREA BY DAYBREAK THU. SCHULTZ .LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON... SURGE OF ARCTIC AIR THURSDAY MORNING WILL BE CONTINUING TO SUPPORT SNOWFALL AS A DISTURBANCE SWING THROUGH WESTERN MONTANA. SURFACE WINDS LOOK TO STAY IN A NORTHEASTERLY ORIENTATION WHICH WILL FAVOR UPSLOPE EFFECTS AND GENERALLY EXPECT 2 TO 6 INCH SNOWFALL AMOUNTS ACROSS THE REGION WITH 4 TO 5 INCHES BEING REALLY COMMON. THIS IS TIMING WITH THE THURSDAY MORNING COMMUTE SO SLICK ROADS AND POOR VISIBILITY SHOULD BE EXPECTED. SNOW DISSIPATES THURSDAY AFTERNOON AND EARLY EVENING AS THE ARCTIC HIGH QUICKLY PULLS TO THE SOUTHEAST AND LEESIDE TROFFING BEGINS ALONG THE FRONT RANGE. THIS PATTERN MAY CAUSE AN EPISODE OF BLOWING SNOW LATE THURSDAY NIGHT AND FRIDAY SO WILL HAVE TO WATCH FOR A BIMODAL WINTER THREAT BUT IT MAY NOT BE CONTINUOUS. TEMPERATURES ON THURSDAY LOOK GO NOWHERE WITH COLD ADVECTION CONTINUING AND CLOUDS AND SNOW ELIMINATING HEATING. WILL BE SOME COLD SPOTS THURSDAY NIGHT ACROSS THE EAST BUT MIXING OVER THE WESTERN ZONES SHOULD LIMIT TEMPERATURES FROM FALLING BELOW ZERO. FRIDAY TEMPERATURES ALREADY MODERATING ACROSS THE AREA WITH WESTERN ZONES TRYING TO APPROACH 30. WINDS WILL BE ON THE INCREASE FOR GAP FLOW AREAS WITH THIS PATTERN CONTINUING INTO SATURDAY. FOR SATURDAY AND BEYOND NORTHWEST FLOW ALOFT LOOKS MOIST AND UNSETTLED WITH A WAFFLING ARCTIC BOUNDARY ACROSS THE REGION. ANALOGS AND CONFIDENCE TOOLKIT DIAGNOSTICS SHOW IT IS NOT A VERY WET PATTERN BUT SOME SHOWER ACTIVITY SHOULD BE EXPECTED WITH MODELS INDICATING A STRONG MOISTURE TAP MOVING INTO THE PACIFIC NORTHWEST. MODELS ARE ALSO SHOWING A BETTER PUSH OF COLD AIR INTO SOUTHEAST MONTANA SATURDAY NIGHT AND SUSPECT THAT THIS MAY BE A RECURRENT THEME THROUGH THE EXTENDED. HAVE ADDED ISOLATED TO SCATTERED SHOWER ACTIVITY FOR PERIODS SATURDAY AND BEYOND. BORSUM && .AVIATION... LIGHT SNOW WITH MVFR CONDITIONS WILL PERSIST INVOF KMLS WITH IFR CONDITIONS TO THE EAST INCLUDING KBHK. VFR CONDITIONS ACROSS WESTERN AREAS WITH GUSTY WINDS ALONG THE FOOTHILLS. EXPECT WINDS TO BECOME EVEN STRONGER AFTER MIDNIGHT TONIGHT. BORSUM && .PRELIMINARY POINT TEMP/POPS... TUE WED THU FRI SAT SUN MON ----------------------------------------------------------- BIL 026/052 033/047 010/014 002/028 017/030 019/039 026/040 00/N 02/R 88/S 12/J 32/J 22/J 22/J LVM 032/049 034/048 012/016 004/028 019/031 024/037 028/040 00/N 02/R 88/S 22/J 32/J 22/J 22/J HDN 020/055 029/048 007/014 908/027 009/029 009/038 018/041 00/B 02/R 88/S 11/B 22/J 22/J 22/J MLS 020/040 026/042 002/008 910/019 002/020 009/031 018/037 10/B 02/R 88/S 11/B 12/J 22/J 22/J 4BQ 019/047 025/048 005/014 908/024 006/025 012/038 021/042 10/B 00/B 58/S 11/B 22/J 22/J 22/J BHK 017/038 022/039 002/008 908/018 004/019 006/028 019/036 60/B 01/B 78/S 10/B 12/J 22/J 22/J SHR 023/051 027/050 008/016 906/025 009/029 012/037 018/043 00/B 01/B 58/S 11/B 22/J 22/J 22/J && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...HIGH WIND WATCH IN EFFECT FROM TUESDAY MORNING THROUGH WEDNESDAY MORNING FOR ZONE 28. WIND ADVISORY IN EFFECT FROM 6 AM TUESDAY TO NOON MST WEDNESDAY FOR ZONE 41. WIND ADVISORY IN EFFECT FROM 2 AM TUESDAY TO NOON MST WEDNESDAY FOR ZONES 65-66. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1132 AM CST MON DEC 16 2013 .UPDATE... ISSUED AT 1035 AM CST MON DEC 16 2013 AFTER A RELATIVELY MILD START TO THE MORNING...TEMPERATURES ARE WARMING RAPIDLY...AIDED IN PART BY CLEAR SKIES AND A DOWNSLOPING COMPONENT TO THE LOW LEVEL WIND. FOR THIS AFTERNOON...MODEL GUIDANCE CONTINUES TO INDICATE COOLING IN MID LEVELS ATOP THE REGION TODAY AS A WAVE ADVANCES SOUTHEAST FROM THE CANADIAN PRAIRIES INTO THE GREAT LAKES REGION. BUT DESPITE THE COOLING ALOFT...LITTLE IMPACT ON THE SURFACE TEMPERATURES IS ANTICIPATED. IN FACT WILL PUSH UP HIGHS SLIGHTLY ACROSS OUR NORTH AS KONL AND KANW HAVE ALREADY ECLIPSED 40F AS OF 10 AM THIS MORNING. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 356 AM CST MON DEC 16 2013 TODAY AND TONIGHT...A POWERFUL THERMAL RIDGE WILL CONTINUE OPERATING ACROSS THE FORECAST AREA. A WEAK COLD FRONT ACROSS SERN MT THIS MORNING COULD DROP THROUGH THE NERN PORTION OF THE FCST AREA THIS AFTERNOON BUT TEMPS BEHIND THE FRONT ARE ABOVE FREEZING SO NO SIGNIFICANT COOLING IS EXPECTED. THE TEMPERATURE FCST TODAY FOLLOWS THE WARMEST MODELS WHICH ARE THE HRRR AND RAP FORECASTING MID TO UPPER 50S ACROSS SWRN NEB. THESE MODELS HAVE VERIFIED THE BEST OVER THE WEEKEND. 40S ARE EXPECTED ACROSS THE SNOW COVER NORTH AND THIS SNOW IS MELTING. WINDS AT H850 MB CONTINUE AT 30 TO 40 KT TODAY WITH 500M AGL WINDS OF 20 TO 25 KTS. THIS WOULD PRODUCE 15 TO 25 MPH WINDS AT THE SFC. THE MID LEVEL CLOUD SHIELD ACROSS WRN SD AND ERN MT IS EXPECTED TO SLICE THROUGH THE NERN PORTION OF THE FCST AREA TODAY WITH SCT-BKN CIRRUS SOUTH AND WEST. HIGH CLOUDS ARE EXPECTED TONIGHT AND THE NAM SUGGESTED MID LEVEL CLOUDS NORTH AND EAST. ALL OF THESE CLOUDS SHOULD LIMIT RADIATIONAL COOLING AND THE BEST GUESS WITH LOWS TONIGHT IS 20S WITH UPPER 20S UNDER THE MID LEVEL CLOUD DECK. H850 MB WINDS WEAKEN TO 10 TO 25 KTS WEST WHICH WOULD SUPPORT MODEST RADIATIONAL COOLING DESPITE THE CLOUD COVER. 30 TO 40KT H850 WINDS CONTINUE NORTH AND EAST SUPPORTING THE WARMER LOWS. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 356 AM CST MON DEC 16 2013 PRIMARY FORECAST CONCERNS DEAL WITH TEMPERATURES THE NEXT SEVERAL DAYS...THEN TURNS TO STRONG FRONTAL PASSAGE THURSDAY WITH COLDER TEMPERATURES AND POSSIBLY SNOW FOR PARTS OF THE AREA. RIDGING ALOFT WILL BUILD OVER THE CENTRAL PLAINS ON TUESDAY IN THE WAKE OF AN UPPER LEVEL SHORTWAVE TROUGH. STILL EXPECT TO SEE AN INFLUENCE ON TEMPERATURES OVER THE NORTHERN PARTS OF NEBRASKA FROM THE SNOWPACK...HOWEVER WITH TEMPERATURES RISING ABOVE FREEZING SHOULD CONTINUE TO SEE THE SNOW MELT IN THE COMING DAYS. DO HAVE A WARMING TREND FOR THE SNOWPACK LOCATIONS...HOWEVER DIDN/T GO TOO WARM YET UNTIL START TO SEE MUCH LESS INFLUENCE FROM THE SNOW. WHERE THE GROUND IS DRY...LOOKING AT HIGHS 10 TO 15 DEGREES WARMER IN THE 50S TO NEAR 60 ON TUESDAY. THE UPPER LEVEL LOW CURRENTLY OVER ALASKA...AS WELL AS THE UPPER LOW OFF THE CALIFORNIA COAST WILL BOTH MAKE THEIR WAY ONTO THE WEST COAST TUESDAY NIGHT AND WEDNESDAY. THESE TWO SYSTEMS WILL STAY SEPARATE...BUT WILL BOTH WORK TO DEEPEN THE TROUGH ACROSS THE WESTERN CONUS. AS THIS OCCURS...THE THERMAL RIDGE WILL STRENGTHEN WITH 850MB TEMPERATURES NEARING 16C. DID INCREASE LOWS FOR TUESDAY NIGHT DUE TO THE WARMING EXPECTED...HOWEVER WITH FAIRLY LIGHT WINDS AND DEWPOINTS IN THE UPPER TEENS AND LOW 20S...MAY STILL GET TEMPERATURES TO FALL INTO THE MID AND UPPER 20S. THIS PERIOD MAY NEED TO BE ADJUSTED IN COMING FORECASTS. THEN FOR WEDNESDAY...SOME PORTIONS OF SOUTHWEST NEBRASKA SHOULD APPROACH OR EXCEED 60 DEGREES. AGAIN...AREAS ACROSS THE NORTH ARE QUESTIONABLE DUE TO THE SNOWPACK. WILL SEE HOW THE NEXT COUPLE OF DAYS MELT THE SNOW AND WILL ADJUST HIGHS IN THESE AREAS AS NEEDED. WINDS LOOK TO BE PRETTY LIGHT ON WEDNESDAY TO LIMIT THE MIXING WITH MODELS ONLY MIXING TO 850MB OR LOWER. IF DEEPER MIXING CAN BE REALIZED TEMPERATURES WILL BE TOO LOW AND NEED TO BE ADJUSTED UPWARDS. FOR EXAMPLE...AT LBF MIXING TO 850MB WEDNESDAY AFTERNOON WOULD BRING A HIGH OF 64 DEGREES. IS SOME DIFFERENCES ON TIMING OF THE ARCTIC FRONT ON THURSDAY...WHICH THEN TRANSLATES TO LOWER CONFIDENCE ON HIGHS. LOOKING AT THE 16.00Z MODELS...THE OPERATIONAL GFS HAS STAYED FAIRLY SIMILAR IN TIMING WHICH IS THE COLDEST SOLUTION. THIS WOULD SUGGEST HIGHS FROM THE UPPER TEENS OVER NORTH CENTRAL NEBRASKA TO THE MID 30S IN THE SOUTHWEST. HOWEVER THE GFS ENSEMBLES ARE SHOWING A VARIETY OF SOLUTIONS AS IT SHOWS A DIFFERENCE OF 5 STANDARD DEVIATIONS FOR MUCH OF THE FORECAST WHICH TRANSLATES TO A 20 DEGREE DIFFERENCE AMONG JUST THE GFS SOLUTIONS. THE ECMWF DID SPEED THE FRONT UP SLIGHTLY WITH THE 16.00Z RUN...HOWEVER THE GEM SLOWED IT DOWN. WITH THE WIDE VARIETY OF SOLUTIONS AND LOWER CONFIDENCE WILL KEEP THE FORECAST FAIRLY SIMILAR TO THE ONGOING FORECAST UNTIL THERE IS BETTER SUPPORT TO GO COLDER. IT DOES CONTINUE TO LOOK LIKE THERE WILL BE SOME POST-FRONTAL PRECIPITATION...HOWEVER IT LOOKS LIKE VERY LIGHT PRECIPITATION. IN THE UPPER LEVEL PATTERN...THE UPPER LOW NOW OFF THE CALIFORNIA COAST WILL MOVE ACROSS THE CENTRAL PLAINS JUST AHEAD OF THE ARCTIC FRONT /WITH LITTLE OR NO IMPACT IN THE SENSIBLE WEATHER/...AND WITH THE WEST COAST SYSTEM DIGGING INTO SOUTHERN CALIFORNIA ON THURSDAY...THERE ISN/T A GOOD MOISTURE FEED INTO THE AREA AS THE ARCTIC FRONT PASSES. THIS WILL LEAD TO A DISJOINTED ATTEMPT AT PRECIPITATION AS LIFT IS NOT IN THE AREA WHEN THE COLUMN SEES THE GREATEST AMOUNT OF MOISTURE...WHILE THE MODELS ARE ALSO SHOWING A DRY LAYER AROUND 700MB TO ALSO INHIBIT PRECIPITATION. CURRENT FORECAST LIMITS THE PRECIPITATION TO MAINLY THE NORTHWEST HALF OF THE FORECAST AREA. HAVE BEEN WATCHING A SIGNAL FOR DRIZZLE ON THURSDAY OVER THE PAST FEW DAYS...AND ALTHOUGH SOUNDINGS WON/T DISCOUNT IT RIGHT NOW WITH THE DRY LAYER EXPECTED...THEY ARE ALSO SHOWING ENOUGH DRY AIR RIGHT AT THE SURFACE WHICH MAY KEEP ANY DRIZZLE FROM BEING A THREAT. THEN AS THE COLUMN COOLS FURTHER WITH THE COLD AIR INTRUSION...AND THE DRY LAYER GOES AWAY...DRIZZLE POTENTIAL WILL DIMINISH WITH ONLY SNOW CHANCES. WILL CONTINUE TO KEEP THE DRIZZLE MENTION OUT OF THE FORECAST FOR NOW AND WATCH IN THE COMING DAYS. BEYOND THURSDAY NIGHT THE MODELS ARE TRYING TO KICK OUT THE COLD AIR TO BRING MORE SEASONABLE TEMPERATURES TO THE FORECAST AREA INTO NEXT WEEKEND. HOWEVER...THE GFS ENSEMBLE MEMBERS ARE ALL OVER THE BOARD WITH STANDARD DEVIATIONS OF 5 TO 7 ON HIGHS AND LOWS FRIDAY THROUGH SUNDAY SO CONFIDENCE IS NOT REAL HIGH AT THIS POINT ON TEMPERATURES THROUGH THAT TIME FRAME AND HAVE USED A CONSENSUS APPROACH FOR THE FORECAST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1132 AM CST MON DEC 16 2013 VFR TO PREVAIL ACROSS ALL WESTERN AND NORTH CENTRAL NEBRASKA TERMINALS THROUGH THE 18Z TAF ISSUANCE PERIOD. OTHERWISE BREEZY NORTHWESTERLY WINDS WILL CONTINUE THIS AFTERNOON FOR MUCH OF THE REGION...BUT SHOULD WEAKEN THIS EVENING AS THE ATMOSPHERE DECOUPLES. AT KVTN...A WEAK BOUNDARY WILL HELP KEEP THE LOWER TROPOSPHERE MIXED THIS EVENING...WITH WIND GUST POTENTIAL OF UP TO 18KTS THROUGH 05Z. THE ONLY OTHER CONCERN TO THE AVIATION COMMUNITY IS THAT GUIDANCE IS PEGGING AN AREA OF 25KT LOW LEVEL WIND SHEAR OVERNIGHT ACROSS NORTH CENTRAL NEBRASKA /INCLUDING KVTN/. BUT WILL NOT INCLUDE A MENTION OF WS IN THE OFFICIAL TAF FOR NOW AS VALUES FALL BELOW ISSUANCE CRITERIA...WILL CONTINUE TO MONITOR. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JACOBS SHORT TERM...CDC LONG TERM...BROOKS AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1036 AM CST MON DEC 16 2013 .UPDATE... ISSUED AT 1035 AM CST MON DEC 16 2013 AFTER A RELATIVELY MILD START TO THE MORNING...TEMPERATURES ARE WARMING RAPIDLY...AIDED IN PART BY CLEAR SKIES AND A DOWNSLOPING COMPONENT TO THE LOW LEVEL WIND. FOR THIS AFTERNOON...MODEL GUIDANCE CONTINUES TO INDICATE COOLING IN MID LEVELS ATOP THE REGION TODAY AS A WAVE ADVANCES SOUTHEAST FROM THE CANADIAN PRAIRIES INTO THE GREAT LAKES REGION. BUT DESPITE THE COOLING ALOFT...LITTLE IMPACT ON THE SURFACE TEMPERATURES IS ANTICIPATED. IN FACT WILL PUSH UP HIGHS SLIGHTLY ACROSS OUR NORTH AS KONL AND KANW HAVE ALREADY ECLIPSED 40F AS OF 10 AM THIS MORNING. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 356 AM CST MON DEC 16 2013 TODAY AND TONIGHT...A POWERFUL THERMAL RIDGE WILL CONTINUE OPERATING ACROSS THE FORECAST AREA. A WEAK COLD FRONT ACROSS SERN MT THIS MORNING COULD DROP THROUGH THE NERN PORTION OF THE FCST AREA THIS AFTERNOON BUT TEMPS BEHIND THE FRONT ARE ABOVE FREEZING SO NO SIGNIFICANT COOLING IS EXPECTED. THE TEMPERATURE FCST TODAY FOLLOWS THE WARMEST MODELS WHICH ARE THE HRRR AND RAP FORECASTING MID TO UPPER 50S ACROSS SWRN NEB. THESE MODELS HAVE VERIFIED THE BEST OVER THE WEEKEND. 40S ARE EXPECTED ACROSS THE SNOW COVER NORTH AND THIS SNOW IS MELTING. WINDS AT H850 MB CONTINUE AT 30 TO 40 KT TODAY WITH 500M AGL WINDS OF 20 TO 25 KTS. THIS WOULD PRODUCE 15 TO 25 MPH WINDS AT THE SFC. THE MID LEVEL CLOUD SHIELD ACROSS WRN SD AND ERN MT IS EXPECTED TO SLICE THROUGH THE NERN PORTION OF THE FCST AREA TODAY WITH SCT-BKN CIRRUS SOUTH AND WEST. HIGH CLOUDS ARE EXPECTED TONIGHT AND THE NAM SUGGESTED MID LEVEL CLOUDS NORTH AND EAST. ALL OF THESE CLOUDS SHOULD LIMIT RADIATIONAL COOLING AND THE BEST GUESS WITH LOWS TONIGHT IS 20S WITH UPPER 20S UNDER THE MID LEVEL CLOUD DECK. H850 MB WINDS WEAKEN TO 10 TO 25 KTS WEST WHICH WOULD SUPPORT MODEST RADIATIONAL COOLING DESPITE THE CLOUD COVER. 30 TO 40KT H850 WINDS CONTINUE NORTH AND EAST SUPPORTING THE WARMER LOWS. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 356 AM CST MON DEC 16 2013 PRIMARY FORECAST CONCERNS DEAL WITH TEMPERATURES THE NEXT SEVERAL DAYS...THEN TURNS TO STRONG FRONTAL PASSAGE THURSDAY WITH COLDER TEMPERATURES AND POSSIBLY SNOW FOR PARTS OF THE AREA. RIDGING ALOFT WILL BUILD OVER THE CENTRAL PLAINS ON TUESDAY IN THE WAKE OF AN UPPER LEVEL SHORTWAVE TROUGH. STILL EXPECT TO SEE AN INFLUENCE ON TEMPERATURES OVER THE NORTHERN PARTS OF NEBRASKA FROM THE SNOWPACK...HOWEVER WITH TEMPERATURES RISING ABOVE FREEZING SHOULD CONTINUE TO SEE THE SNOW MELT IN THE COMING DAYS. DO HAVE A WARMING TREND FOR THE SNOWPACK LOCATIONS...HOWEVER DIDN/T GO TOO WARM YET UNTIL START TO SEE MUCH LESS INFLUENCE FROM THE SNOW. WHERE THE GROUND IS DRY...LOOKING AT HIGHS 10 TO 15 DEGREES WARMER IN THE 50S TO NEAR 60 ON TUESDAY. THE UPPER LEVEL LOW CURRENTLY OVER ALASKA...AS WELL AS THE UPPER LOW OFF THE CALIFORNIA COAST WILL BOTH MAKE THEIR WAY ONTO THE WEST COAST TUESDAY NIGHT AND WEDNESDAY. THESE TWO SYSTEMS WILL STAY SEPARATE...BUT WILL BOTH WORK TO DEEPEN THE TROUGH ACROSS THE WESTERN CONUS. AS THIS OCCURS...THE THERMAL RIDGE WILL STRENGTHEN WITH 850MB TEMPERATURES NEARING 16C. DID INCREASE LOWS FOR TUESDAY NIGHT DUE TO THE WARMING EXPECTED...HOWEVER WITH FAIRLY LIGHT WINDS AND DEWPOINTS IN THE UPPER TEENS AND LOW 20S...MAY STILL GET TEMPERATURES TO FALL INTO THE MID AND UPPER 20S. THIS PERIOD MAY NEED TO BE ADJUSTED IN COMING FORECASTS. THEN FOR WEDNESDAY...SOME PORTIONS OF SOUTHWEST NEBRASKA SHOULD APPROACH OR EXCEED 60 DEGREES. AGAIN...AREAS ACROSS THE NORTH ARE QUESTIONABLE DUE TO THE SNOWPACK. WILL SEE HOW THE NEXT COUPLE OF DAYS MELT THE SNOW AND WILL ADJUST HIGHS IN THESE AREAS AS NEEDED. WINDS LOOK TO BE PRETTY LIGHT ON WEDNESDAY TO LIMIT THE MIXING WITH MODELS ONLY MIXING TO 850MB OR LOWER. IF DEEPER MIXING CAN BE REALIZED TEMPERATURES WILL BE TOO LOW AND NEED TO BE ADJUSTED UPWARDS. FOR EXAMPLE...AT LBF MIXING TO 850MB WEDNESDAY AFTERNOON WOULD BRING A HIGH OF 64 DEGREES. IS SOME DIFFERENCES ON TIMING OF THE ARCTIC FRONT ON THURSDAY...WHICH THEN TRANSLATES TO LOWER CONFIDENCE ON HIGHS. LOOKING AT THE 16.00Z MODELS...THE OPERATIONAL GFS HAS STAYED FAIRLY SIMILAR IN TIMING WHICH IS THE COLDEST SOLUTION. THIS WOULD SUGGEST HIGHS FROM THE UPPER TEENS OVER NORTH CENTRAL NEBRASKA TO THE MID 30S IN THE SOUTHWEST. HOWEVER THE GFS ENSEMBLES ARE SHOWING A VARIETY OF SOLUTIONS AS IT SHOWS A DIFFERENCE OF 5 STANDARD DEVIATIONS FOR MUCH OF THE FORECAST WHICH TRANSLATES TO A 20 DEGREE DIFFERENCE AMONG JUST THE GFS SOLUTIONS. THE ECMWF DID SPEED THE FRONT UP SLIGHTLY WITH THE 16.00Z RUN...HOWEVER THE GEM SLOWED IT DOWN. WITH THE WIDE VARIETY OF SOLUTIONS AND LOWER CONFIDENCE WILL KEEP THE FORECAST FAIRLY SIMILAR TO THE ONGOING FORECAST UNTIL THERE IS BETTER SUPPORT TO GO COLDER. IT DOES CONTINUE TO LOOK LIKE THERE WILL BE SOME POST-FRONTAL PRECIPITATION...HOWEVER IT LOOKS LIKE VERY LIGHT PRECIPITATION. IN THE UPPER LEVEL PATTERN...THE UPPER LOW NOW OFF THE CALIFORNIA COAST WILL MOVE ACROSS THE CENTRAL PLAINS JUST AHEAD OF THE ARCTIC FRONT /WITH LITTLE OR NO IMPACT IN THE SENSIBLE WEATHER/...AND WITH THE WEST COAST SYSTEM DIGGING INTO SOUTHERN CALIFORNIA ON THURSDAY...THERE ISN/T A GOOD MOISTURE FEED INTO THE AREA AS THE ARCTIC FRONT PASSES. THIS WILL LEAD TO A DISJOINTED ATTEMPT AT PRECIPITATION AS LIFT IS NOT IN THE AREA WHEN THE COLUMN SEES THE GREATEST AMOUNT OF MOISTURE...WHILE THE MODELS ARE ALSO SHOWING A DRY LAYER AROUND 700MB TO ALSO INHIBIT PRECIPITATION. CURRENT FORECAST LIMITS THE PRECIPITATION TO MAINLY THE NORTHWEST HALF OF THE FORECAST AREA. HAVE BEEN WATCHING A SIGNAL FOR DRIZZLE ON THURSDAY OVER THE PAST FEW DAYS...AND ALTHOUGH SOUNDINGS WON/T DISCOUNT IT RIGHT NOW WITH THE DRY LAYER EXPECTED...THEY ARE ALSO SHOWING ENOUGH DRY AIR RIGHT AT THE SURFACE WHICH MAY KEEP ANY DRIZZLE FROM BEING A THREAT. THEN AS THE COLUMN COOLS FURTHER WITH THE COLD AIR INTRUSION...AND THE DRY LAYER GOES AWAY...DRIZZLE POTENTIAL WILL DIMINISH WITH ONLY SNOW CHANCES. WILL CONTINUE TO KEEP THE DRIZZLE MENTION OUT OF THE FORECAST FOR NOW AND WATCH IN THE COMING DAYS. BEYOND THURSDAY NIGHT THE MODELS ARE TRYING TO KICK OUT THE COLD AIR TO BRING MORE SEASONABLE TEMPERATURES TO THE FORECAST AREA INTO NEXT WEEKEND. HOWEVER...THE GFS ENSEMBLE MEMBERS ARE ALL OVER THE BOARD WITH STANDARD DEVIATIONS OF 5 TO 7 ON HIGHS AND LOWS FRIDAY THROUGH SUNDAY SO CONFIDENCE IS NOT REAL HIGH AT THIS POINT ON TEMPERATURES THROUGH THAT TIME FRAME AND HAVE USED A CONSENSUS APPROACH FOR THE FORECAST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 514 AM CST MON DEC 16 2013 VFR IS EXPECTED ALL AREAS TODAY AND TONIGHT. SCT-BKN MID AND HIGH LEVEL CLOUDS WILL CONTINUE MOVING SOUTHEAST THROUGH THE REGION. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JACOBS SHORT TERM...CDC LONG TERM...BROOKS AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
518 AM CST MON DEC 16 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 356 AM CST MON DEC 16 2013 TODAY AND TONIGHT...A POWERFUL THERMAL RIDGE WILL CONTINUE OPERATING ACROSS THE FORECAST AREA. A WEAK COLD FRONT ACROSS SERN MT THIS MORNING COULD DROP THROUGH THE NERN PORTION OF THE FCST AREA THIS AFTERNOON BUT TEMPS BEHIND THE FRONT ARE ABOVE FREEZING SO NO SIGNIFICANT COOLING IS EXPECTED. THE TEMPERATURE FCST TODAY FOLLOWS THE WARMEST MODELS WHICH ARE THE HRRR AND RAP FORECASTING MID TO UPPER 50S ACROSS SWRN NEB. THESE MODELS HAVE VERIFIED THE BEST OVER THE WEEKEND. 40S ARE EXPECTED ACROSS THE SNOW COVER NORTH AND THIS SNOW IS MELTING. WINDS AT H850 MB CONTINUE AT 30 TO 40 KT TODAY WITH 500M AGL WINDS OF 20 TO 25 KTS. THIS WOULD PRODUCE 15 TO 25 MPH WINDS AT THE SFC. THE MID LEVEL CLOUD SHIELD ACROSS WRN SD AND ERN MT IS EXPECTED TO SLICE THROUGH THE NERN PORTION OF THE FCST AREA TODAY WITH SCT-BKN CIRRUS SOUTH AND WEST. HIGH CLOUDS ARE EXPECTED TONIGHT AND THE NAM SUGGESTED MID LEVEL CLOUDS NORTH AND EAST. ALL OF THESE CLOUDS SHOULD LIMIT RADIATIONAL COOLING AND THE BEST GUESS WITH LOWS TONIGHT IS 20S WITH UPPER 20S UNDER THE MID LEVEL CLOUD DECK. H850 MB WINDS WEAKEN TO 10 TO 25 KTS WEST WHICH WOULD SUPPORT MODEST RADIATIONAL COOLING DESPITE THE CLOUD COVER. 30 TO 40KT H850 WINDS CONTINUE NORTH AND EAST SUPPORTING THE WARMER LOWS. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 356 AM CST MON DEC 16 2013 PRIMARY FORECAST CONCERNS DEAL WITH TEMPERATURES THE NEXT SEVERAL DAYS...THEN TURNS TO STRONG FRONTAL PASSAGE THURSDAY WITH COLDER TEMPERATURES AND POSSIBLY SNOW FOR PARTS OF THE AREA. RIDGING ALOFT WILL BUILD OVER THE CENTRAL PLAINS ON TUESDAY IN THE WAKE OF AN UPPER LEVEL SHORTWAVE TROUGH. STILL EXPECT TO SEE AN INFLUENCE ON TEMPERATURES OVER THE NORTHERN PARTS OF NEBRASKA FROM THE SNOWPACK...HOWEVER WITH TEMPERATURES RISING ABOVE FREEZING SHOULD CONTINUE TO SEE THE SNOW MELT IN THE COMING DAYS. DO HAVE A WARMING TREND FOR THE SNOWPACK LOCATIONS...HOWEVER DIDN/T GO TOO WARM YET UNTIL START TO SEE MUCH LESS INFLUENCE FROM THE SNOW. WHERE THE GROUND IS DRY...LOOKING AT HIGHS 10 TO 15 DEGREES WARMER IN THE 50S TO NEAR 60 ON TUESDAY. THE UPPER LEVEL LOW CURRENTLY OVER ALASKA...AS WELL AS THE UPPER LOW OFF THE CALIFORNIA COAST WILL BOTH MAKE THEIR WAY ONTO THE WEST COAST TUESDAY NIGHT AND WEDNESDAY. THESE TWO SYSTEMS WILL STAY SEPARATE...BUT WILL BOTH WORK TO DEEPEN THE TROUGH ACROSS THE WESTERN CONUS. AS THIS OCCURS...THE THERMAL RIDGE WILL STRENGTHEN WITH 850MB TEMPERATURES NEARING 16C. DID INCREASE LOWS FOR TUESDAY NIGHT DUE TO THE WARMING EXPECTED...HOWEVER WITH FAIRLY LIGHT WINDS AND DEWPOINTS IN THE UPPER TEENS AND LOW 20S...MAY STILL GET TEMPERATURES TO FALL INTO THE MID AND UPPER 20S. THIS PERIOD MAY NEED TO BE ADJUSTED IN COMING FORECASTS. THEN FOR WEDNESDAY...SOME PORTIONS OF SOUTHWEST NEBRASKA SHOULD APPROACH OR EXCEED 60 DEGREES. AGAIN...AREAS ACROSS THE NORTH ARE QUESTIONABLE DUE TO THE SNOWPACK. WILL SEE HOW THE NEXT COUPLE OF DAYS MELT THE SNOW AND WILL ADJUST HIGHS IN THESE AREAS AS NEEDED. WINDS LOOK TO BE PRETTY LIGHT ON WEDNESDAY TO LIMIT THE MIXING WITH MODELS ONLY MIXING TO 850MB OR LOWER. IF DEEPER MIXING CAN BE REALIZED TEMPERATURES WILL BE TOO LOW AND NEED TO BE ADJUSTED UPWARDS. FOR EXAMPLE...AT LBF MIXING TO 850MB WEDNESDAY AFTERNOON WOULD BRING A HIGH OF 64 DEGREES. IS SOME DIFFERENCES ON TIMING OF THE ARCTIC FRONT ON THURSDAY...WHICH THEN TRANSLATES TO LOWER CONFIDENCE ON HIGHS. LOOKING AT THE 16.00Z MODELS...THE OPERATIONAL GFS HAS STAYED FAIRLY SIMILAR IN TIMING WHICH IS THE COLDEST SOLUTION. THIS WOULD SUGGEST HIGHS FROM THE UPPER TEENS OVER NORTH CENTRAL NEBRASKA TO THE MID 30S IN THE SOUTHWEST. HOWEVER THE GFS ENSEMBLES ARE SHOWING A VARIETY OF SOLUTIONS AS IT SHOWS A DIFFERENCE OF 5 STANDARD DEVIATIONS FOR MUCH OF THE FORECAST WHICH TRANSLATES TO A 20 DEGREE DIFFERENCE AMONG JUST THE GFS SOLUTIONS. THE ECMWF DID SPEED THE FRONT UP SLIGHTLY WITH THE 16.00Z RUN...HOWEVER THE GEM SLOWED IT DOWN. WITH THE WIDE VARIETY OF SOLUTIONS AND LOWER CONFIDENCE WILL KEEP THE FORECAST FAIRLY SIMILAR TO THE ONGOING FORECAST UNTIL THERE IS BETTER SUPPORT TO GO COLDER. IT DOES CONTINUE TO LOOK LIKE THERE WILL BE SOME POST-FRONTAL PRECIPITATION...HOWEVER IT LOOKS LIKE VERY LIGHT PRECIPITATION. IN THE UPPER LEVEL PATTERN...THE UPPER LOW NOW OFF THE CALIFORNIA COAST WILL MOVE ACROSS THE CENTRAL PLAINS JUST AHEAD OF THE ARCTIC FRONT /WITH LITTLE OR NO IMPACT IN THE SENSIBLE WEATHER/...AND WITH THE WEST COAST SYSTEM DIGGING INTO SOUTHERN CALIFORNIA ON THURSDAY...THERE ISN/T A GOOD MOISTURE FEED INTO THE AREA AS THE ARCTIC FRONT PASSES. THIS WILL LEAD TO A DISJOINTED ATTEMPT AT PRECIPITATION AS LIFT IS NOT IN THE AREA WHEN THE COLUMN SEES THE GREATEST AMOUNT OF MOISTURE...WHILE THE MODELS ARE ALSO SHOWING A DRY LAYER AROUND 700MB TO ALSO INHIBIT PRECIPITATION. CURRENT FORECAST LIMITS THE PRECIPITATION TO MAINLY THE NORTHWEST HALF OF THE FORECAST AREA. HAVE BEEN WATCHING A SIGNAL FOR DRIZZLE ON THURSDAY OVER THE PAST FEW DAYS...AND ALTHOUGH SOUNDINGS WON/T DISCOUNT IT RIGHT NOW WITH THE DRY LAYER EXPECTED...THEY ARE ALSO SHOWING ENOUGH DRY AIR RIGHT AT THE SURFACE WHICH MAY KEEP ANY DRIZZLE FROM BEING A THREAT. THEN AS THE COLUMN COOLS FURTHER WITH THE COLD AIR INTRUSION...AND THE DRY LAYER GOES AWAY...DRIZZLE POTENTIAL WILL DIMINISH WITH ONLY SNOW CHANCES. WILL CONTINUE TO KEEP THE DRIZZLE MENTION OUT OF THE FORECAST FOR NOW AND WATCH IN THE COMING DAYS. BEYOND THURSDAY NIGHT THE MODELS ARE TRYING TO KICK OUT THE COLD AIR TO BRING MORE SEASONABLE TEMPERATURES TO THE FORECAST AREA INTO NEXT WEEKEND. HOWEVER...THE GFS ENSEMBLE MEMBERS ARE ALL OVER THE BOARD WITH STANDARD DEVIATIONS OF 5 TO 7 ON HIGHS AND LOWS FRIDAY THROUGH SUNDAY SO CONFIDENCE IS NOT REAL HIGH AT THIS POINT ON TEMPERATURES THROUGH THAT TIME FRAME AND HAVE USED A CONSENSUS APPROACH FOR THE FORECAST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 514 AM CST MON DEC 16 2013 VFR IS EXPECTED ALL AREAS TODAY AND TONIGHT. SCT-BKN MID AND HIGH LEVEL CLOUDS WILL CONTINUE MOVING SOUTHEAST THROUGH THE REGION. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...CDC LONG TERM...BROOKS AVIATION...CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
357 AM CST MON DEC 16 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 356 AM CST MON DEC 16 2013 TODAY AND TONIGHT...A POWERFUL THERMAL RIDGE WILL CONTINUE OPERATING ACROSS THE FORECAST AREA. A WEAK COLD FRONT ACROSS SERN MT THIS MORNING COULD DROP THROUGH THE NERN PORTION OF THE FCST AREA THIS AFTERNOON BUT TEMPS BEHIND THE FRONT ARE ABOVE FREEZING SO NO SIGNIFICANT COOLING IS EXPECTED. THE TEMPERATURE FCST TODAY FOLLOWS THE WARMEST MODELS WHICH ARE THE HRRR AND RAP FORECASTING MID TO UPPER 50S ACROSS SWRN NEB. THESE MODELS HAVE VERIFIED THE BEST OVER THE WEEKEND. 40S ARE EXPECTED ACROSS THE SNOW COVER NORTH AND THIS SNOW IS MELTING. WINDS AT H850 MB CONTINUE AT 30 TO 40 KT TODAY WITH 500M AGL WINDS OF 20 TO 25 KTS. THIS WOULD PRODUCE 15 TO 25 MPH WINDS AT THE SFC. THE MID LEVEL CLOUD SHIELD ACROSS WRN SD AND ERN MT IS EXPECTED TO SLICE THROUGH THE NERN PORTION OF THE FCST AREA TODAY WITH SCT-BKN CIRRUS SOUTH AND WEST. HIGH CLOUDS ARE EXPECTED TONIGHT AND THE NAM SUGGESTED MID LEVEL CLOUDS NORTH AND EAST. ALL OF THESE CLOUDS SHOULD LIMIT RADIATIONAL COOLING AND THE BEST GUESS WITH LOWS TONIGHT IS 20S WITH UPPER 20S UNDER THE MID LEVEL CLOUD DECK. H850 MB WINDS WEAKEN TO 10 TO 25 KTS WEST WHICH WOULD SUPPORT MODEST RADIATIONAL COOLING DESPITE THE CLOUD COVER. 30 TO 40KT H850 WINDS CONTINUE NORTH AND EAST SUPPORTING THE WARMER LOWS. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 356 AM CST MON DEC 16 2013 PRIMARY FORECAST CONCERNS DEAL WITH TEMPERATURES THE NEXT SEVERAL DAYS...THEN TURNS TO STRONG FRONTAL PASSAGE THURSDAY WITH COLDER TEMPERATURES AND POSSIBLY SNOW FOR PARTS OF THE AREA. RIDGING ALOFT WILL BUILD OVER THE CENTRAL PLAINS ON TUESDAY IN THE WAKE OF AN UPPER LEVEL SHORTWAVE TROUGH. STILL EXPECT TO SEE AN INFLUENCE ON TEMPERATURES OVER THE NORTHERN PARTS OF NEBRASKA FROM THE SNOWPACK...HOWEVER WITH TEMPERATURES RISING ABOVE FREEZING SHOULD CONTINUE TO SEE THE SNOW MELT IN THE COMING DAYS. DO HAVE A WARMING TREND FOR THE SNOWPACK LOCATIONS...HOWEVER DIDN/T GO TOO WARM YET UNTIL START TO SEE MUCH LESS INFLUENCE FROM THE SNOW. WHERE THE GROUND IS DRY...LOOKING AT HIGHS 10 TO 15 DEGREES WARMER IN THE 50S TO NEAR 60 ON TUESDAY. THE UPPER LEVEL LOW CURRENTLY OVER ALASKA...AS WELL AS THE UPPER LOW OFF THE CALIFORNIA COAST WILL BOTH MAKE THEIR WAY ONTO THE WEST COAST TUESDAY NIGHT AND WEDNESDAY. THESE TWO SYSTEMS WILL STAY SEPARATE...BUT WILL BOTH WORK TO DEEPEN THE TROUGH ACROSS THE WESTERN CONUS. AS THIS OCCURS...THE THERMAL RIDGE WILL STRENGTHEN WITH 850MB TEMPERATURES NEARING 16C. DID INCREASE LOWS FOR TUESDAY NIGHT DUE TO THE WARMING EXPECTED...HOWEVER WITH FAIRLY LIGHT WINDS AND DEWPOINTS IN THE UPPER TEENS AND LOW 20S...MAY STILL GET TEMPERATURES TO FALL INTO THE MID AND UPPER 20S. THIS PERIOD MAY NEED TO BE ADJUSTED IN COMING FORECASTS. THEN FOR WEDNESDAY...SOME PORTIONS OF SOUTHWEST NEBRASKA SHOULD APPROACH OR EXCEED 60 DEGREES. AGAIN...AREAS ACROSS THE NORTH ARE QUESTIONABLE DUE TO THE SNOWPACK. WILL SEE HOW THE NEXT COUPLE OF DAYS MELT THE SNOW AND WILL ADJUST HIGHS IN THESE AREAS AS NEEDED. WINDS LOOK TO BE PRETTY LIGHT ON WEDNESDAY TO LIMIT THE MIXING WITH MODELS ONLY MIXING TO 850MB OR LOWER. IF DEEPER MIXING CAN BE REALIZED TEMPERATURES WILL BE TOO LOW AND NEED TO BE ADJUSTED UPWARDS. FOR EXAMPLE...AT LBF MIXING TO 850MB WEDNESDAY AFTERNOON WOULD BRING A HIGH OF 64 DEGREES. IS SOME DIFFERENCES ON TIMING OF THE ARCTIC FRONT ON THURSDAY...WHICH THEN TRANSLATES TO LOWER CONFIDENCE ON HIGHS. LOOKING AT THE 16.00Z MODELS...THE OPERATIONAL GFS HAS STAYED FAIRLY SIMILAR IN TIMING WHICH IS THE COLDEST SOLUTION. THIS WOULD SUGGEST HIGHS FROM THE UPPER TEENS OVER NORTH CENTRAL NEBRASKA TO THE MID 30S IN THE SOUTHWEST. HOWEVER THE GFS ENSEMBLES ARE SHOWING A VARIETY OF SOLUTIONS AS IT SHOWS A DIFFERENCE OF 5 STANDARD DEVIATIONS FOR MUCH OF THE FORECAST WHICH TRANSLATES TO A 20 DEGREE DIFFERENCE AMONG JUST THE GFS SOLUTIONS. THE ECMWF DID SPEED THE FRONT UP SLIGHTLY WITH THE 16.00Z RUN...HOWEVER THE GEM SLOWED IT DOWN. WITH THE WIDE VARIETY OF SOLUTIONS AND LOWER CONFIDENCE WILL KEEP THE FORECAST FAIRLY SIMILAR TO THE ONGOING FORECAST UNTIL THERE IS BETTER SUPPORT TO GO COLDER. IT DOES CONTINUE TO LOOK LIKE THERE WILL BE SOME POST-FRONTAL PRECIPITATION...HOWEVER IT LOOKS LIKE VERY LIGHT PRECIPITATION. IN THE UPPER LEVEL PATTERN...THE UPPER LOW NOW OFF THE CALIFORNIA COAST WILL MOVE ACROSS THE CENTRAL PLAINS JUST AHEAD OF THE ARCTIC FRONT /WITH LITTLE OR NO IMPACT IN THE SENSIBLE WEATHER/...AND WITH THE WEST COAST SYSTEM DIGGING INTO SOUTHERN CALIFORNIA ON THURSDAY...THERE ISN/T A GOOD MOISTURE FEED INTO THE AREA AS THE ARCTIC FRONT PASSES. THIS WILL LEAD TO A DISJOINTED ATTEMPT AT PRECIPITATION AS LIFT IS NOT IN THE AREA WHEN THE COLUMN SEES THE GREATEST AMOUNT OF MOISTURE...WHILE THE MODELS ARE ALSO SHOWING A DRY LAYER AROUND 700MB TO ALSO INHIBIT PRECIPITATION. CURRENT FORECAST LIMITS THE PRECIPITATION TO MAINLY THE NORTHWEST HALF OF THE FORECAST AREA. HAVE BEEN WATCHING A SIGNAL FOR DRIZZLE ON THURSDAY OVER THE PAST FEW DAYS...AND ALTHOUGH SOUNDINGS WON/T DISCOUNT IT RIGHT NOW WITH THE DRY LAYER EXPECTED...THEY ARE ALSO SHOWING ENOUGH DRY AIR RIGHT AT THE SURFACE WHICH MAY KEEP ANY DRIZZLE FROM BEING A THREAT. THEN AS THE COLUMN COOLS FURTHER WITH THE COLD AIR INTRUSION...AND THE DRY LAYER GOES AWAY...DRIZZLE POTENTIAL WILL DIMINISH WITH ONLY SNOW CHANCES. WILL CONTINUE TO KEEP THE DRIZZLE MENTION OUT OF THE FORECAST FOR NOW AND WATCH IN THE COMING DAYS. BEYOND THURSDAY NIGHT THE MODELS ARE TRYING TO KICK OUT THE COLD AIR TO BRING MORE SEASONABLE TEMPERATURES TO THE FORECAST AREA INTO NEXT WEEKEND. HOWEVER...THE GFS ENSEMBLE MEMBERS ARE ALL OVER THE BOARD WITH STANDARD DEVIATIONS OF 5 TO 7 ON HIGHS AND LOWS FRIDAY THROUGH SUNDAY SO CONFIDENCE IS NOT REAL HIGH AT THIS POINT ON TEMPERATURES THROUGH THAT TIME FRAME AND HAVE USED A CONSENSUS APPROACH FOR THE FORECAST. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1115 PM CST SUN DEC 15 2013 WITH ONLY MIDDLE AND HIGH CLOUD CEILINGS AND NO RESTRICTIONS TO VISIBILITY...FLIGHT CONDITIONS WILL BE UNRESTRICTED THROUGH MONDAY EVENING. WIND 270-300 AT LESS THAN 10KT WILL INCREASE TO 10-14KT BY LATE MONDAY MORNING OR EARLY AFTERNOON. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...CDC LONG TERM...BROOKS AVIATION...SPRINGER
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
309 PM EST MON DEC 16 2013 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL TRACK FROM THE UPPER OHIO VALLEY TO OFF THE NEW JERSEY COAST BY TUESDAY AFTERNOON. THIS LOW WILL BRING A LIGHT SNOWFALL TO MUCH OF CENTRAL NEW YORK AND A MODERATE SNOWFALL TO PARTS OF NORTHEAST PENNSYLVANIA AND THE CATSKILLS FROM LATE TONIGHT THROUGH TUESDAY. AFTER THIS LOW PASSES BY...COLD AIR WILL REMAIN ACROSS THE REGION THROUGH WEDNESDAY WITH MORE LAKE EFFECT SNOW SHOWERS AND FLURRIES. MUCH MILDER AIR WILL BEGIN TO RETURN TO THE REGION BY THE END OF THE WEEK AS A SOUTHWESTERLY FLOW OF AIR BECOMES ESTABLISHED ACROSS THE EASTERN UNITED STATES. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... SINGLE SHORELINE LAKE EFFECT SNOW BAND OFF LAKE ONTARIO HAS NOW SHIFTED INLAND AND WAS BREAKING UP INTO MULTIPLE BANDS OF LESS ORGANIZED SNOW SHOWERS AND FLURRIES. RAP MODEL SOUNDINGS SHOW A PRONOUNCED SHIFT TO NW FLOW UNDER THE INVERSION AT 18-19Z AND INDEED THE KTYX 88D SHOWS A NW FLO ARND 340 DEGREES AT 3000 FEET AGL. IN ADDTN...SUBSDC WILL CONT TO PUSH THE INVERSION DOWN WHICH AS PER MODEL SOUNDINGS IS PROJECTED TO DROP TO ARND 3000 FEET AGL FROM 7000 FEET AGL AT PRESENT. BY 00 TO 01Z...THE LL FLOW BACKS TO THE SW. THIS IN EFFECT WILL CUT OFF THE LES SNOWS AND FLURRIES BY 03Z THE LATEST. FOR ACCUMULATIONS...I CAN SEE ANTHR 1-2 INCHES BTWN SYR AND CORTLAND IN THE HIGHLANDS OF CENTRAL NY. REST OF CWA WILL SEE PC SKIES THIS AFTERNOON WITH SCATTERED FLURRIES AS THE TEMPERATURES IN THE BNDRY LAYER UNDER THE INVERSION WERE IN THE MAXIMUM ZONE OF ICE CRYSTAL FORMATION ARND -12C TO 15C (AT 1000 MB MAX GROWTH IS -12C). HENCE FLOW OVER THE HILLS AND EVEN A LITTLE CONVECTIVE OVERTURNING IN SC CLDS WILL SPIT OUT SOME FLURRIES. FARTHER AWAY FROM THE LAKES IN NE PA...WHERE BNDRY LAYER WAS DRIER...FLURRIES WERE SUBLIMATING SO HAVE NO POPS THERE. AFTER SUNSET...WITH THE LOSS OF THE SFC HEATING AND THE LL FLOW TURNING MORE W-SW...SKIES SHUD CLR AND THE LES ACVTY WILL END AS STATED ABV. I SEE RAPID COOLING IN THE BNDRY LAYER...UNTIL HIGHER CLDS BEGIN ARRIVING FROM THE SW BTWN 6 AND 9Z AHEAD OF CLIPPER SYSTEM. I HAVE SOME LIGHT SNOWS AND FLURRIES ARRIVING FROM 9Z TO 12Z ACRS ENTIRE FORECAST AREA FROM APPROACHING CLIPPER SYSTEM. SO I HAVE ADDED POPS LATE. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... ISSUED WINTER WEATHER ADVY FOR TUESDAY FROM 5 AM TO 5 PM FOR THE APPROACHING CLIPPER-LIKE SYSTEM. ALL SYNOPTIC AND MESOSCALE MODELS SHOW A DECENT SHOT OF SIGNIFICANT WAA/ISEN LIFT WITH ENUF MOISTURE TO SQUEEZE OUT AT LEAST .1 TO .2 INCHES OF QPF...WITH POTENTIALLY A LITTLE MORE ACRS PIKE/SULLIVAN CO/S. ASSUMING A 15 TO 1 SNOW TO QPF RATIO I CAN SEE ARND 3-5 INCHES IN THESE TWO COUNTIES WHICH MEETS OUR ADVY CRITERIA OF 4 INCHES/12 HOURS. SO IN COLLABORATION WITH SURROUNDING OFFICES WE ISSUED A WW ADVY FOR SNOW. WPC WWD GRAPHIC ALSO IN LINE SHOWING A SMALL AREA OF 4-6 INCHES IN SULLIVAN/PIKE CO/S. REST OF CWA WE FEEL WILL SEE MAINLY 1-3 INCHES. WILL MENTION IN HWO AS ROADS LIKELY WILL BE HAZARDOUS TO SOME EXTENT TUE AM FOR REST OF FORECAST AREA. AFTER THIS SYSTEM PASSES BY...AN UPR LVL TROF WILL PUSH SOUTHEAST ACRS THE REGION WITH MODEST CAA. I KEPT CHC SN SHOWERS/FLURRIES IN AS SOME LAKE EFFECT MOISTURE WILL CONT TO STREAM INTO C NY AND NRN PA UNDER THIS COLDER AIR ALOFT. HIGHEST POPS AND AMNTS WILL BE IN OUR FAR NRN COUNTIES DIRECTLY DOWNWIND OF LAKE ONTARIO. MAY NEED TO CONSIDER LES ADVYS LATER IN THIS PERIOD FOR MAINLY WEDNESDAY. THEN FOR WED NGT SOME WAA KICKS IN COINCIDENT WITH RISING HGHTS SO THERE LIKELY WILL BE SOME LIMITED AMNTS OF LIFTG TO SUPPORT JUST A CHC POPS FOR SN SHOWERS/FLURRIES. THEN FOR THURSDAY...SW FLO SETS UP IN EARNEST AS TEMPS BEGIN TO SOAR AT 850 MB. THIS WILL CUT OFF ALL LAKE EFFECT MOISTURE AND START A TURN TO MUCH MILDER WX FOR OUR REGION. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... MEDIUM RANGE MODELS ARE NOW IN MUCH BETTER AGREEMENT DURING THIS ACTIVE EXTENDED FORECAST PERIOD. THE UPPER LEVEL PATTERN WILL FEATURE A DEEP WESTERN TROF AND STRONG SOUTHEAST RIDGE THAT WILL PROVIDE A FAIRLY MILD DEEP SOUTHWEST FLOW ACROSS THE NORTHEAST. AT THE SFC, THURSDAY NIGHT THROUGH FRIDAY NIGHT, SFC LOW PRES WILL TRACK FROM THE MID WEST NORTHEAST ACROSS THE UPPER GREAT LAKES THEN EAST ACROSS NEARBY SOUTHERN CANADA. AS THIS SYSTEM PASSES TO OUR WEST WARM AIR WILL OVERSPREAD THE AREA BRINGING MAINLY RAIN SHOWERS ON FRIDAY. FRIDAY NIGHT THE TRAILING COLD FRONT IS EXPECTED TO CROSS THE AREA WITH MIXED RAIN/SNOW SHOWERS POSSIBLE. SATURDAY MAY BE MAINLY DRY AS SFC HIGH PRES BRIEFLY BUILDS SOUTH OVER THE NORTHEAST. SATURDAY NIGHT THROUGH SUNDAY NIGHT, ANOTHER LOW PRES SYSTEM WILL MOVE NORTHEAST ALONG THIS STALLED BOUNDARY AND INTO THE NORTHEAST. A STRONG THERMAL GRADIENT WILL RESIDE OVER THE REGION THEREFORE DETERMINING P-TYPE WILL BE VERY DIFFICULT. FOR NOW WILL MENTION BOTH RAIN/SNOW. CURRENT TREND IS FOR A WARMER SOLUTION SO THIS SECOND WAVE COULD BE ASSOCIATED WITH SIGNIFICANT RAINFALL. STILL MUCH TO BE DETERMINED. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... A WEAK SFC TROF IS PASSING THROUGH THE REGION THIS AFTERNOON WITH WIDESPREAD FLURRIES AND OCCASIONAL MVFR CONDITIONS. AT KSYR, A BETTER DEFINED LAKE SNOW BAND WILL BRING OCCASIONAL IFR CONDITIONS THROUGH 22Z. BY THIS EVENING WEAK FLOW AND SOME LOW LEVEL DRYING SHOULD RESULT IN VFR CONDITIONS FOR MUCH OF THE OVERNIGHT PERIOD. A SYSTEM PASSING TO OUR SOUTH WILL SPREAD IFR/MVFR SNOW ACROSS THE TERMINALS BEGINNING 10Z-12Z. THE LOWER RESTRICTIONS ARE EXPECTED OVER THE SRN/CNTRL TERMINALS. NORTHWEST WINDS AT 1O KNOTS WITH GUST AROUND 18 KNOTS BECOMING LIGHT THIS EVENING THEN SOUTHEAST AT 5-10 KNOTS ON TUESDAY. OUTLOOK... TUESDAY THROUGH WEDNESDAY...RESTRICTIONS POSSIBLE FROM SNOW SHOWERS. WEDNESDAY NIGHT THROUGH THURSDAY...BECOMING VFR. THURSDAY NIGHT THROUGH SATURDAY...RESTRICTIONS POSSIBLE IN RAIN/SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...WINTER WEATHER ADVISORY FROM 5 AM TO 5 PM EST TUESDAY FOR PAZ048. NY...WINTER WEATHER ADVISORY FROM 5 AM TO 5 PM EST TUESDAY FOR NYZ062. && $$ SYNOPSIS...DJN NEAR TERM...DJN SHORT TERM...DJN LONG TERM...RRM AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
224 PM EST MON DEC 16 2013 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL TRACK FROM THE UPPER OHIO VALLEY TO OFF THE NEW JERSEY COAST BY TUESDAY AFTERNOON. THIS LOW WILL BRING A LIGHT SNOWFALL TO MUCH OF CENTRAL NEW YORK AND A MODERATE SNOWFALL TO PARTS OF NORTHEAST PENNSYLVANIA AND THE CATSKILLS FROM LATE TONIGHT THROUGH TUESDAY. AFTER THIS LOW PASSES BY...COLD AIR WILL REMAIN ACROSS THE REGION THROUGH WEDNESDAY WITH MORE LAKE EFFECT SNOW SHOWERS AND FLURRIES. MUCH MILDER AIR WILL BEGIN TO RETURN TO THE REGION BY THE END OF THE WEEK AS A SOUTHWESTERLY FLOW OF AIR BECOMES ESTABLISHED ACROSS THE EASTERN UNITED STATES. && .NEAR TERM /THROUGH TONIGHT/... SINGLE SHORELINE LAKE EFFECT SNOW BAND OFF LAKE ONTARIO HAS NOW SHIFTED INLAND AND WAS BREAKING UP INTO MULTIPLE BANDS OF LESS ORGANIZED SNOW SHOWERS AND FLURRIES. RAP MODEL SOUNDINGS SHOW A PRONOUNCED SHIFT TO NW FLOW UNDER THE INVERSION AT 18-19Z AND INDEED THE KTYX 88D SHOWS A NW FLO ARND 340 DEGREES AT 3000 FEET AGL. IN ADDTN...SUBSDC WILL CONT TO PUSH THE INVERSION DOWN WHICH AS PER MODEL SOUNDINGS IS PROJECTED TO DROP TO ARND 3000 FEET AGL FROM 7000 FEET AGL AT PRESENT. BY 00 TO 01Z...THE LL FLOW BACKS TO THE SW. THIS IN EFFECT WILL CUT OFF THE LES SNOWS AND FLURRIES BY 03Z THE LATEST. FOR ACCUMULATIONS...I CAN SEE ANTHR 1-2 INCHES BTWN SYR AND CORTLAND IN THE HIGHLANDS OF CENTRAL NY. REST OF CWA WILL SEE PC SKIES THIS AFTERNOON WITH SCATTERED FLURRIES AS THE TEMPERATURES IN THE BNDRY LAYER UNDER THE INVERSION WERE IN THE MAXIMUM ZONE OF ICE CRYSTAL FORMATION ARND -12C TO 15C (AT 1000 MB MAX GROWTH IS -12C). HENCE FLOW OVER THE HILLS AND EVEN A LITTLE CONVECTIVE OVERTURNING IN SC CLDS WILL SPIT OUT SOME FLURRIES. FARTHER AWAY FROM THE LAKES IN NE PA...WHERE BNDRY LAYER WAS DRIER...FLURRIES WERE SUBLIMATING SO HAVE NO POPS THERE. AFTER SUNSET...WITH THE LOSS OF THE SFC HEATING AND THE LL FLOW TURNING MORE W-SW...SKIES SHUD CLR AND THE LES ACVTY WILL END AS STATED ABV. I SEE RAPID COOLING IN THE BNDRY LAYER...UNTIL HIGHER CLDS BEGIN ARRIVING FROM THE SW BTWN 6 AND 9Z AHEAD OF CLIPPER SYSTEM. I HAVE SOME LIGHT SNOWS AND FLURRIES ARRIVING FROM 9Z TO 12Z ACRS ENTIRE FORECAST AREA FROM APPROACHING CLIPPER SYSTEM. SO I HAVE ADDED POPS LATE. && .SHORT TERM /TUESDAY THROUGH THURSDAY/... XPCT SCT -SHSN TO PREVAIL ON TUE NGT WITH A SFC TROF IN THE VCNTY...AIDED BY ANOTHER S/WV. IT APPEARS THAT LES SNOWS WILL DVLP ON WED AS THE SFC TROF DEPARTS AND FLOW BCMS MORE WRLY. ACTIVITY SHUD BE FAIRLY SHORT LIVED AS WINDS COME ARND TO THE SW WED EVNG AS LOW PRES MOVS INTO THE CNTRL GTLAKES. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... MEDIUM RANGE MODELS ARE NOW IN MUCH BETTER AGREEMENT DURING THIS ACTIVE EXTENDED FORECAST PERIOD. THE UPPER LEVEL PATTERN WILL FEATURE A DEEP WESTERN TROF AND STRONG SOUTHEAST RIDGE THAT WILL PROVIDE A FAIRLY MILD DEEP SOUTHWEST FLOW ACROSS THE NORTHEAST. AT THE SFC, THURSDAY NIGHT THROUGH FRIDAY NIGHT, SFC LOW PRES WILL TRACK FROM THE MID WEST NORTHEAST ACROSS THE UPPER GREAT LAKES THEN EAST ACROSS NEARBY SOUTHERN CANADA. AS THIS SYSTEM PASSES TO OUR WEST WARM AIR WILL OVERSPREAD THE AREA BRINGING MAINLY RAIN SHOWERS ON FRIDAY. FRIDAY NIGHT THE TRAILING COLD FRONT IS EXPECTED TO CROSS THE AREA WITH MIXED RAIN/SNOW SHOWERS POSSIBLE. SATURDAY MAY BE MAINLY DRY AS SFC HIGH PRES BRIEFLY BUILDS SOUTH OVER THE NORTHEAST. SATURDAY NIGHT THROUGH SUNDAY NIGHT, ANOTHER LOW PRES SYSTEM WILL MOVE NORTHEAST ALONG THIS STALLED BOUNDARY AND INTO THE NORTHEAST. A STRONG THERMAL GRADIENT WILL RESIDE OVER THE REGION THEREFORE DETERMINING P-TYPE WILL BE VERY DIFFICULT. FOR NOW WILL MENTION BOTH RAIN/SNOW. CURRENT TREND IS FOR A WARMER SOLUTION SO THIS SECOND WAVE COULD BE ASSOCIATED WITH SIGNIFICANT RAINFALL. STILL MUCH TO BE DETERMINED. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... A WEAK SFC TROF IS PASSING THROUGH THE REGION THIS AFTERNOON WITH WIDESPREAD FLURRIES AND OCCASIONAL MVFR CONDITIONS. AT KSYR, A BETTER DEFINED LAKE SNOW BAND WILL BRING OCCASIONAL IFR CONDITIONS THROUGH 22Z. BY THIS EVENING WEAK FLOW AND SOME LOW LEVEL DRYING SHOULD RESULT IN VFR CONDITIONS FOR MUCH OF THE OVERNIGHT PERIOD. A SYSTEM PASSING TO OUR SOUTH WILL SPREAD IFR/MVFR SNOW ACROSS THE TERMINALS BEGINNING 10Z-12Z. THE LOWER RESTRICTIONS ARE EXPECTED OVER THE SRN/CNTRL TERMINALS. NORTHWEST WINDS AT 1O KNOTS WITH GUST AROUND 18 KNOTS BECOMING LIGHT THIS EVENING THEN SOUTHEAST AT 5-10 KNOTS ON TUESDAY. OUTLOOK... TUESDAY THROUGH WEDNESDAY...RESTRICTIONS POSSIBLE FROM SNOW SHOWERS. WEDNESDAY NIGHT THROUGH THURSDAY...BECOMING VFR. THURSDAY NIGHT THROUGH SATURDAY...RESTRICTIONS POSSIBLE IN RAIN/SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJN NEAR TERM...DJN SHORT TERM... LONG TERM...RRM AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
145 PM EST MON DEC 16 2013 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL TRACK FROM THE UPPER OHIO VALLEY TO OFF THE NEW JERSEY COAST BY TUESDAY AFTERNOON. THIS LOW WILL BRING A LIGHT SNOWFALL TO MUCH OF CENTRAL NEW YORK AND A MODERATE SNOWFALL TO PARTS OF NORTHEAST PENNSYLVANIA AND THE CATSKILLS FROM LATE TONIGHT THROUGH TUESDAY. AFTER THIS LOW PASSES BY...COLD AIR WILL REMAIN ACROSS THE REGION THROUGH WEDNESDAY WITH MORE LAKE EFFECT SNOW SHOWERS AND FLURRIES. MUCH MILDER AIR WILL BEGIN TO RETURN TO THE REGION BY THE END OF THE WEEK AS A SOUTHWESTERLY FLOW OF AIR BECOMES ESTABLISHED ACROSS THE EASTERN UNITED STATES. && .NEAR TERM /THROUGH TONIGHT/... SINGLE SHORELINE LAKE EFFECT SNOW BAND OFF LAKE ONTARIO HAS NOW SHIFTED INLAND AND WAS BREAKING UP INTO MULTIPLE BANDS OF LESS ORGANIZED SNOW SHOWERS AND FLURRIES. RAP MODEL SOUNDINGS SHOW A PRONOUNCED SHIFT TO NW FLOW UNDER THE INVERSION AT 18-19Z AND INDEED THE KTYX 88D SHOWS A NW FLO ARND 340 DEGREES AT 3000 FEET AGL. IN ADDTN...SUBSDC WILL CONT TO PUSH THE INVERSION DOWN WHICH AS PER MODEL SOUNDINGS IS PROJECTED TO DROP TO ARND 3000 FEET AGL FROM 7000 FEET AGL AT PRESENT. BY 00 TO 01Z...THE LL FLOW BACKS TO THE SW. THIS IN EFFECT WILL CUT OFF THE LES SNOWS AND FLURRIES BY 03Z THE LATEST. FOR ACCUMULATIONS...I CAN SEE ANTHR 1-2 INCHES BTWN SYR AND CORTLAND IN THE HIGHLANDS OF CENTRAL NY. REST OF CWA WILL SEE PC SKIES THIS AFTERNOON WITH SCATTERED FLURRIES AS THE TEMPERATURES IN THE BNDRY LAYER UNDER THE INVERSION WERE IN THE MAXIMUM ZONE OF ICE CRYSTAL FORMATION ARND -12C TO 15C (AT 1000 MB MAX GROWTH IS -12C). HENCE FLOW OVER THE HILLS AND EVEN A LITTLE CONVECTIVE OVERTURNING IN SC CLDS WILL SPIT OUT SOME FLURRIES. FARTHER AWAY FROM THE LAKES IN NE PA...WHERE BNDRY LAYER WAS DRIER...FLURRIES WERE SUBLIMATING SO HAVE NO POPS THERE. AFTER SUNSET...WITH THE LOSS OF THE SFC HEATING AND THE LL FLOW TURNING MORE W-SW...SKIES SHUD CLR AND THE LES ACVTY WILL END AS STATED ABV. I SEE RAPID COOLING IN THE BNDRY LAYER...UNTIL HIGHER CLDS BEGIN ARRIVING FROM THE SW BTWN 6 AND 9Z AHEAD OF CLIPPER SYSTEM. I HAVE SOME LIGHT SNOWS AND FLURRIES ARRIVING FROM 9Z TO 12Z ACRS ENTIRE FORECAST AREA FROM APPROACHING CLIPPER SYSTEM. SO I HAVE ADDED POPS LATE. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... XPCT SCT -SHSN TO PREVAIL ON TUE NGT WITH A SFC TROF IN THE VCNTY...AIDED BY ANOTHER S/WV. IT APPEARS THAT LES SNOWS WILL DVLP ON WED AS THE SFC TROF DEPARTS AND FLOW BCMS MORE WRLY. ACTIVITY SHUD BE FAIRLY SHORT LIVED AS WINDS COME ARND TO THE SW WED EVNG AS LOW PRES MOVS INTO THE CNTRL GTLAKES. && .LONG TERM /THURSDAY THROUGH MONDAY/... UPPER LEVEL PATTERN THROUGH MUCH OF THE EXTENDED FEATURES A NEGATIVE PNA PATTERN, WRN TROF/ERN RIDGE. MAINLY DRY WEATHER IS EXPECTED WEDNESDAY NIGHT THROUGH THURSDAY NIGHT AS SFC HIGH PRES WILL BE OFF THE MID ATLANTIC WITH LOW PRES MOVING INTO THE UPPER GREAT LAKES. SOUTHWEST FLOW WILL PROVIDE MODERATING CONDITIONS. LATTER PART OF THE EXTENDED SHOWS THE MEDIUM RANGE MODELS WITH SIGNIFICANT DIFFERENCES. FOLLOWED WPC GUIDANCE WHICH FOLLOWS THE ECMWF. ON FRIDAY, SFC LOW PRES MOVING THROUGH EASTERN CANADA WILL BRING RAIN SHOWERS FOLLOWED BY MIXED RAIN/SNOW SHOWERS AFTER FROPA FRIDAY NIGHT. THIS BOUNDARY THEN STALLS JUST SOUTH OF AREA WITH SEVERAL WAVES MOVING NORTHEAST ALONG BOUNDARY. THIS WILL BRING A CONTINUATION OF CHC POPS FOR RAIN/SNOW SHOWERS. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... A WEAK SFC TROF IS PASSING THROUGH THE REGION THIS AFTERNOON WITH WIDESPREAD FLURRIES AND OCCASIONAL MVFR CONDITIONS. AT KSYR, A BETTER DEFINED LAKE SNOW BAND WILL BRING OCCASIONAL IFR CONDITIONS THROUGH 22Z. BY THIS EVENING WEAK FLOW AND SOME LOW LEVEL DRYING SHOULD RESULT IN VFR CONDITIONS FOR MUCH OF THE OVERNIGHT PERIOD. A SYSTEM PASSING TO OUR SOUTH WILL SPREAD IFR/MVFR SNOW ACROSS THE TERMINALS BEGINNING 10Z-12Z. THE LOWER RESTRICTIONS ARE EXPECTED OVER THE SRN/CNTRL TERMINALS. NORTHWEST WINDS AT 1O KNOTS WITH GUST AROUND 18 KNOTS BECOMING LIGHT THIS EVENING THEN SOUTHEAST AT 5-10 KNOTS ON TUESDAY. OUTLOOK... TUESDAY THROUGH WEDNESDAY...RESTRICTIONS POSSIBLE FROM SNOW SHOWERS. WEDNESDAY NIGHT THROUGH THURSDAY...BECOMING VFR. THURSDAY NIGHT THROUGH SATURDAY...RESTRICTIONS POSSIBLE IN RAIN/SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJN NEAR TERM...DJN SHORT TERM... LONG TERM...PVN/RRM AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1252 PM EST MON DEC 16 2013 .SYNOPSIS... A SERIES OF CLIPPERS WILL BRING PERIODS OF LIGHT SNOW OR SNOW SHOWERS TO CENTRAL NEW YORK AND NORTHEAST PENNSYLVANIA THROUGH MIDWEEK. LAKE EFFECT SNOW SHOWERS WILL ALSO BE POSSIBLE AT TIMES EAST AND SOUTHEAST OF LAKE ONTARIO. TEMPERATURES WILL BEGIN TO MODERATE BY THE END OF THE WEEK. && .NEAR TERM /THROUGH TUESDAY/... KBGM AND KTYX 88D/S CONT TO SHOW A NARROW LES BAND ACRS LAKE ONTARIO E OF SODUS BAY INTO NW ONONDAGA CO WHERE IT BECOMES MORE DIFFUSE. VIS SATL IMAGERY ALSO SHOWS THIS BAND WHICH EVENTUALLY SNAKES DOWN THRU SRN MADISON...OTSEGO TO SCHOHARIE COUNTIES. THE BAND LOSES ITS ORGANIZATION IN THE MTNS OF CORTLAND SRN MADISON AND CHENANGO/OTSEGO CO/S. THE FLOW WAS RATHER LIGHT IN THE SFC LAYER RUNNING LESS THAN 10 KNOTS FROM THE W OR NW. BUT THE 925 MB FLO REMAINS ARND 10-15 KTS AND CONTS TO DIRECT LAKE MOISTURE IN NC NY FROM LAKE ONTARIO THRU THE AFTERNOON ON A 290 TO 300 DEGREE FLOW. TEMPS WERE VERY COLD UNDER THE INVERSION WHICH WERE ARND -20C NR 7000 FEET AGL. THE INVERSION LOWERS FROM 7000 FEET TO 3000 FEET AGL BY 23Z. THIS OCCURS AS THE COLD BUILDS IN AT LOWER LEVELS WITH -18C AT 3000 FEET AGL BY 22Z AS PER LATEST RAP MODEL SOUNDING AT KSYR. THE MEAN WIND BELOW THE INVERSION REMAINS FROM 290-300 DEGREES SO WILL CONT WITH CAT TO LIKELY POPS ACRS ONONDAGA TO MADISON/SRN ONEIDA CO/S WITH JUST MINOR TWEAKS FROM PREV SHIFT. HAVE 2-4 INCHES OF SNOW FALLING UP THERE BY LATE EVENING. DECIDED AGAINST AN LES ADVY BECAUSE THERE WAS SHEAR IN THE LOW- LEVELS...THE FLO WEAKENS LATER THIS AFTERNOON AND THERE WAS LARGE SCALE SUBSC PUSHING THE INVERSION DOWN. REST OF CWA WILL SEE SCT-BKN SC WITH FLURRIES AS THE MAX GROWTH ZONE FOR ICE CRYSTALS IS NOT FAR ABV THE SFC. THIS MEANS THAT ANY LIFTG EITHER OROGRAPHIC OR SIMPLY SOME WEAK CONVECTIVE OVERTURNING IN AN SC CLOUD CUD PRODUCE A FEW FLAKES FOR THE REMAINDER OF THE AFTERNOON. SUBSC CONTS TO WORK IN ACRS THE CWA TONIGHT. THE LES WILL EVENTUALLY WEAKEN AND SHIFT N OF THE CWA AS THE FLOW TURNS MORE SWRLY BY 3Z OR SO. CLDS FROM NEXT SYSTEM WILL ADVECT OVHD LATER IN THE NIGHT. HENCE I SEE MAINLY CLR SKIES MUCH OF CWA LEADING TO SIGNIFICANT NET RAD COOLING IN THE EVENING...THINK TEMPS WILL FALL QUICKLY...THEN REBOUND SOME LATE TONIGHT AS THE CLDS INCREASE AND THICKEN. LATEST LAV GUIDC SUGGESTS THIS. PREVIOUS DISCUSSION IS BELOW... 445 AM UPDATE...LES ADVISORY FOR NRN ONEIDA CANCELLED. PREV BLO... ARCTIC FNT ENTERING THE NRN CWA EARLY THIS MRNG SHIFTING THE LOW LVL FLOW TO MORE OF A NWLY DIRECTION. LES SNOW WILL LIKELY REMAIN OVER ONON/MADISON AND FAR SRN ONEIDA TDA. VERY DRY LOW LVL AIR WORKING INTO THE RGN BEHIND THIS FNT...AND LOW LVL FLOW WEAKENS LATER THIS MRNG. XPCT ACCUMS GNRLY IN THE 2-3 INCH RNG FOR MUCH OF THIS AREA TDA. THIS ACTIVITY WILL GRADUALLY SHIFT NWD LATE TDA INTO THE EVNG HRS AS LOW LVL FLOW BACKS. SCT -SHSN ACRS PORTIONS OF THE SRN TIER INTO NE PA THIS MRNG DUE TO ERIE STREAMER. LATE TNGT NXT S/WV...CRNTLY OVER SRN CANADA...WILL DIVE SEWD INTO THE FCST AREA. AREA OF LGT SNOW WILL BEGIN TO WORK INTO THE RGN AFTER 06Z. MIN TEMPS TNGT LIKELY TO BE ARND 06Z WITH STEADY OR SLOWLY RISING TEMPS AFTERWARDS. THIS AREA OF SNOW SHUD PUSH EWD AND OUT OF THE RGN BY LATE MRNG OR EARLY AFTN...BUT NXT S/WV IS RIGHT ON IT`S HEELS WHICH MAY SPREAD MORE LGT SNOW ACRS THE RGN LATER IN THE AFTN. ATTM...WE ARE ANTICIPATING ACCUMS IN THE 2-4 INCH RNG WITH THIS SYSTEM. WILL HAVE TO MONITOR 2NDRY CYCLOGENESIS OFF THE JERSEY CST WHICH COULD BUMP UP AMTS A BIT ACRS THE CATSKILLS AND POCONOS. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... XPCT SCT -SHSN TO PREVAIL ON TUE NGT WITH A SFC TROF IN THE VCNTY...AIDED BY ANOTHER S/WV. IT APPEARS THAT LES SNOWS WILL DVLP ON WED AS THE SFC TROF DEPARTS AND FLOW BCMS MORE WRLY. ACTIVITY SHUD BE FAIRLY SHORT LIVED AS WINDS COME ARND TO THE SW WED EVNG AS LOW PRES MOVS INTO THE CNTRL GTLAKES. && .LONG TERM /THURSDAY THROUGH MONDAY/... UPPER LEVEL PATTERN THROUGH MUCH OF THE EXTENDED FEATURES A NEGATIVE PNA PATTERN, WRN TROF/ERN RIDGE. MAINLY DRY WEATHER IS EXPECTED WEDNESDAY NIGHT THROUGH THURSDAY NIGHT AS SFC HIGH PRES WILL BE OFF THE MID ATLANTIC WITH LOW PRES MOVING INTO THE UPPER GREAT LAKES. SOUTHWEST FLOW WILL PROVIDE MODERATING CONDITIONS. LATTER PART OF THE EXTENDED SHOWS THE MEDIUM RANGE MODELS WITH SIGNIFICANT DIFFERENCES. FOLLOWED WPC GUIDANCE WHICH FOLLOWS THE ECMWF. ON FRIDAY, SFC LOW PRES MOVING THROUGH EASTERN CANADA WILL BRING RAIN SHOWERS FOLLOWED BY MIXED RAIN/SNOW SHOWERS AFTER FROPA FRIDAY NIGHT. THIS BOUNDARY THEN STALLS JUST SOUTH OF AREA WITH SEVERAL WAVES MOVING NORTHEAST ALONG BOUNDARY. THIS WILL BRING A CONTINUATION OF CHC POPS FOR RAIN/SNOW SHOWERS. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... A WEAK SFC TROF IS PASSING THROUGH THE REGION THIS AFTERNOON WITH WIDESPREAD FLURRIES AND OCCASIONAL MVFR CONDITIONS. AT KSYR, A BETTER DEFINED LAKE SNOW BAND WILL BRING OCCASIONAL IFR CONDITIONS THROUGH 22Z. BY THIS EVENING WEAK FLOW AND SOME LOW LEVEL DRYING SHOULD RESULT IN VFR CONDITIONS FOR MUCH OF THE OVERNIGHT PERIOD. A SYSTEM PASSING TO OUR SOUTH WILL SPREAD IFR/MVFR SNOW ACROSS THE TERMINALS BEGINNING 10Z-12Z. THE LOWER RESTRICTIONS ARE EXPECTED OVER THE SRN/CNTRL TERMINALS. NORTHWEST WINDS AT 1O KNOTS WITH GUST AROUND 18 KNOTS BECOMING LIGHT THIS EVENING THEN SOUTHEAST AT 5-10 KNOTS ON TUESDAY. OUTLOOK... TUESDAY THROUGH WEDNESDAY...RESTRICTIONS POSSIBLE FROM SNOW SHOWERS. WEDNESDAY NIGHT THROUGH THURSDAY...BECOMING VFR. THURSDAY NIGHT THROUGH SATURDAY...RESTRICTIONS POSSIBLE IN RAIN/SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJN NEAR TERM...DJN SHORT TERM... LONG TERM...PVN/RRM AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1026 AM EST MON DEC 16 2013 .SYNOPSIS... A SERIES OF CLIPPERS WILL BRING PERIODS OF LIGHT SNOW OR SNOW SHOWERS TO CENTRAL NEW YORK AND NORTHEAST PENNSYLVANIA THROUGH MIDWEEK. LAKE EFFECT SNOW SHOWERS WILL ALSO BE POSSIBLE AT TIMES EAST AND SOUTHEAST OF LAKE ONTARIO. TEMPERATURES WILL BEGIN TO MODERATE BY THE END OF THE WEEK. && .NEAR TERM /THROUGH TUESDAY/... KBGM AND KTYX 88D/S CONT TO SHOW A NARROW LES BAND ACRS LAKE ONTARIO E OF SODUS BAY INTO NW ONONDAGA CO WHERE IT BECOMES MORE DIFFUSE. VIS SATL IMAGERY ALSO SHOWS THIS BAND WHICH EVENTUALLY SNAKES DOWN THRU SRN MADISON...OTSEGO TO SCHOHARIE COUNTIES. THE BAND LOSES ITS ORGANIZATION IN THE MTNS OF CORTLAND SRN MADISON AND CHENANGO/OTSEGO CO/S. THE FLOW WAS RATHER LIGHT IN THE SFC LAYER RUNNING LESS THAN 10 KNOTS FROM THE W OR NW. BUT THE 925 MB FLO REMAINS ARND 10-15 KTS AND CONTS TO DIRECT LAKE MOISTURE IN NC NY FROM LAKE ONTARIO THRU THE AFTERNOON ON A 290 TO 300 DEGREE FLOW. TEMPS WERE VERY COLD UNDER THE INVERSION WHICH WERE ARND -20C NR 7000 FEET AGL. THE INVERSION LOWERS FROM 7000 FEET TO 3000 FEET AGL BY 23Z. THIS OCCURS AS THE COLD BUILDS IN AT LOWER LEVELS WITH -18C AT 3000 FEET AGL BY 22Z AS PER LATEST RAP MODEL SOUNDING AT KSYR. THE MEAN WIND BELOW THE INVERSION REMAINS FROM 290-300 DEGREES SO WILL CONT WITH CAT TO LIKELY POPS ACRS ONONDAGA TO MADISON/SRN ONEIDA CO/S WITH JUST MINOR TWEAKS FROM PREV SHIFT. HAVE 2-4 INCHES OF SNOW FALLING UP THERE BY LATE EVENING. DECIDED AGAINST AN LES ADVY BECAUSE THERE WAS SHEAR IN THE LOW- LEVELS...THE FLO WEAKENS LATER THIS AFTERNOON AND THERE WAS LARGE SCALE SUBSC PUSHING THE INVERSION DOWN. REST OF CWA WILL SEE SCT-BKN SC WITH FLURRIES AS THE MAX GROWTH ZONE FOR ICE CRYSTALS IS NOT FAR ABV THE SFC. THIS MEANS THAT ANY LIFTG EITHER OROGRAPHIC OR SIMPLY SOME WEAK CONVECTIVE OVERTURNING IN AN SC CLOUD CUD PRODUCE A FEW FLAKES FOR THE REMAINDER OF THE AFTERNOON. SUBSC CONTS TO WORK IN ACRS THE CWA TONIGHT. THE LES WILL EVENTUALLY WEAKEN AND SHIFT N OF THE CWA AS THE FLOW TURNS MORE SWRLY BY 3Z OR SO. CLDS FROM NEXT SYSTEM WILL ADVECT OVHD LATER IN THE NIGHT. HENCE I SEE MAINLY CLR SKIES MUCH OF CWA LEADING TO SIGNIFICANT NET RAD COOLING IN THE EVENING...THINK TEMPS WILL FALL QUICKLY...THEN REBOUND SOME LATE TONIGHT AS THE CLDS INCREASE AND THICKEN. LATEST LAV GUIDC SUGGESTS THIS. PREVIOUS DISCUSSION IS BELOW... 445 AM UPDATE...LES ADVISORY FOR NRN ONEIDA CANCELLED. PREV BLO... ARCTIC FNT ENTERING THE NRN CWA EARLY THIS MRNG SHIFTING THE LOW LVL FLOW TO MORE OF A NWLY DIRECTION. LES SNOW WILL LIKELY REMAIN OVER ONON/MADISON AND FAR SRN ONEIDA TDA. VERY DRY LOW LVL AIR WORKING INTO THE RGN BEHIND THIS FNT...AND LOW LVL FLOW WEAKENS LATER THIS MRNG. XPCT ACCUMS GNRLY IN THE 2-3 INCH RNG FOR MUCH OF THIS AREA TDA. THIS ACTIVITY WILL GRADUALLY SHIFT NWD LATE TDA INTO THE EVNG HRS AS LOW LVL FLOW BACKS. SCT -SHSN ACRS PORTIONS OF THE SRN TIER INTO NE PA THIS MRNG DUE TO ERIE STREAMER. LATE TNGT NXT S/WV...CRNTLY OVER SRN CANADA...WILL DIVE SEWD INTO THE FCST AREA. AREA OF LGT SNOW WILL BEGIN TO WORK INTO THE RGN AFTER 06Z. MIN TEMPS TNGT LIKELY TO BE ARND 06Z WITH STEADY OR SLOWLY RISING TEMPS AFTERWARDS. THIS AREA OF SNOW SHUD PUSH EWD AND OUT OF THE RGN BY LATE MRNG OR EARLY AFTN...BUT NXT S/WV IS RIGHT ON IT`S HEELS WHICH MAY SPREAD MORE LGT SNOW ACRS THE RGN LATER IN THE AFTN. ATTM...WE ARE ANTICIPATING ACCUMS IN THE 2-4 INCH RNG WITH THIS SYSTEM. WILL HAVE TO MONITOR 2NDRY CYCLOGENESIS OFF THE JERSEY CST WHICH COULD BUMP UP AMTS A BIT ACRS THE CATSKILLS AND POCONOS. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... XPCT SCT -SHSN TO PREVAIL ON TUE NGT WITH A SFC TROF IN THE VCNTY...AIDED BY ANOTHER S/WV. IT APPEARS THAT LES SNOWS WILL DVLP ON WED AS THE SFC TROF DEPARTS AND FLOW BCMS MORE WRLY. ACTIVITY SHUD BE FAIRLY SHORT LIVED AS WINDS COME ARND TO THE SW WED EVNG AS LOW PRES MOVS INTO THE CNTRL GTLAKES. && .LONG TERM /THURSDAY THROUGH SUNDAY/... UPPER LEVEL PATTERN THROUGH MUCH OF THE EXTENDED FEATURES A NEGATIVE PNA PATTERN, WRN TROF/ERN RIDGE. MAINLY DRY WEATHER IS EXPECTED WEDNESDAY NIGHT THROUGH THURSDAY NIGHT AS SFC HIGH PRES WILL BE OFF THE MID ATLANTIC WITH LOW PRES MOVING INTO THE UPPER GREAT LAKES. SOUTHWEST FLOW WILL PROVIDE MODERATING CONDITIONS. LATTER PART OF THE EXTENDED SHOWS THE MEDIUM RANGE MODELS WITH SIGNIFICANT DIFFERENCES. FOLLOWED WPC GUIDANCE WHICH FOLLOWS THE ECMWF. ON FRIDAY, SFC LOW PRES MOVING THROUGH EASTERN CANADA WILL BRING RAIN SHOWERS FOLLOWED BY MIXED RAIN/SNOW SHOWERS AFTER FROPA FRIDAY NIGHT. THIS BOUNDARY THEN STALLS JUST SOUTH OF AREA WITH SEVERAL WAVES MOVING NORTHEAST ALONG BOUNDARY. THIS WILL BRING A CONTINUATION OF CHC POPS FOR RAIN/SNOW SHOWERS. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... 12Z UPDATE... LAKE SNOWS WILL CONTINUE OFF AND ON THROUGH THE DAY WITH OCNL MVFR/IFR RESTRICTIONS AT KSYR. EXPECT IFR VSBYS IN BLOWING SNOW BETWEEN NOW AND 16Z. REMAINDER OF TERMINALS SHOULD BE VFR TODAY WITH OCNL MVFR RESTRICTION POSSIBLY PASSING THROUGH BUT NOT ENOUGH CONFIDENCE TO INCLUDE IN TAFS AT THIS TIME. LIGHT MVFR SNOWS MOVE IN AFTER 10Z FROM THE WEST ON TUESDAY FOR ALL BUT KRME. W-NW WINDS AROUND 10-12KTS WILL GUST DURING THE DAY TO AROUND 20KTS. WINDS BCM LGT/VRB OVERNIGHT THEN BECOME SERLY AROUND 5KTS TOWARD 12Z. OUTLOOK... TUESDAY THROUGH WEDNESDAY...RESTRICTIONS POSSIBLE FROM SNOW SHOWERS. WEDNESDAY NIGHT THROUGH THURSDAY...BECOMING VFR. THURSDAY NIGHT AND FRIDAY...RESTRICTIONS POSSIBLE IN RAIN SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJN NEAR TERM...DJN SHORT TERM... LONG TERM...PVN/RRM AVIATION...PVN
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1213 AM EST MON DEC 16 2013 .SYNOPSIS... A COLD WEST FLOW OF AIR CROSSING THE LOWER GREAT LAKES WILL CONTINUE TO GENERATE LAKE EFFECT SNOWS EAST AND SOUTHEAST OF THE LAKES INTO MONDAY. A CLIPPER SYSTEM BRINGS ANOTHER GENERAL LIGHT SNOWFALL MONDAY NIGHT THROUGH TUESDAY NIGHT. TEMPERATURES WILL RISE ABOVE NORMAL TOWARD THE END OF THE WEEK WITH A CHANCE FOR RAIN FRIDAY AHEAD OF THE NEXT STORM SYSTEM. && .NEAR TERM /THROUGH TODAY/... WESTERLY FLOW ACROSS THE LAKES WILL CONTINUE LAKE EFFECT SNOWS OVERNIGHT. A COLD FRONT DROPPING SOUTH ACROSS LAKE ONTARIO WILL CROSS SOUTH ACROSS NEW YORK OVERNIGHT WITH WINDS VEERING TO NORTHWEST. THIS WILL SHIFT THE LAKE BANDS FURTHER SOUTH THROUGH THE EARLY MORNING. OFF LAKE ERIE...THE LAKE EFFECT SNOW BAND EXTENDS WEST TO EAST ACROSS ALONG THE I-86 CORRIDOR AT MIDNIGHT. THE BAND HAS WEAKENED SOME FROM EARLIER IN THE EVENING BUT SNOW RATES UP TO AN INCH AN HOUR WILL CONTINUE INTO THE EARLY MORNING HOURS. THE LAKE SNOW ADVISORY FOR WYOMING HAS BEEN DROPPED AND THE LAKE SNOW WARNINGS FOR CHAUTAUQUA AND CATTARAUGUS COUNTIES AND THE ADVISORY FOR ALLEGANY HAVE BEEN EXTENDED THROUGH 15Z. MESOSCALE GUIDANCE INCLUDING THE HRRR AND RGEM CONTINUE TO SHOW LAKE SNOWS WILL CONTINUING INTO THE EARLY MORNING HOURS BUT IN A BIT WEAKER STATE AS THE FRONT DROPS SOUTH SHIFTING THE LAKE BANDS TO A NORTHWEST-SOUTHEAST ORIENTATION. THE SHORTER FETCH ACROSS THE LAKE WILL BREAK THE BAND INTO WEAKER MULTI-BANDS WHICH WILL PRODUCE AN ADDITIONAL 3-5 INCHES THROUGH THE MORNING. OFF LAKE ONTARIO...A VERY STRONG LONG AXIS PARALLEL LAKE BAND AS OF MIDNIGHT IS SHOWING SIGNS OF SHIFTING SOUTHWARD AS THE COLD FRONT BEGINS TO CROSS LAKE ONTARIO. LAKE EFFECT SNOW WARNINGS WERE ADDED TO JEFFERSON AND LEWIS COUNTIES AS REPORTS OF SNOW RATES EXCEEDING 3-4 INCHES PER HOUR HAVE BEEN OBSERVED BENEATH THE BAND. MESOSCALE GUIDANCE HERE SUGGESTS THE BAND WILL SLOWLY SHIFT SOUTH SOUTH AS STEERING WINDS VEER TO NORTHWESTERLY BEHIND THE COLD FRONT SHIFTING SOUTH OF THE LAKE. THE BAND WILL DRIFT SOUTH THROUGH 10Z THEN RUN ALONG THE SOUTHEASTERN LAKE ONTARIO SHORELINE THROUGH THE REMAINDER OF THE NIGHT. THE HIGHER QPF IS EXPECTED ACROSS OSWEGO COUNTY THROUGH THE EVENT SO A WARNING REMAINS HERE. SNOWFALL RATES OF ONE-TWO OR MORE INCHES PER HOUR CAN BRING 7-14 INCHES OF SNOW POSSIBLY OVERNIGHT. ONCE THE BAND BECOMES MORE NORTHWEST-SOUTHEAST ORIENTED THEN LAKE SNOWS WILL BEGIN TO ACCUMULATE ACROSS NORTHERN CAYUGA AND WAYNE COUNTIES TOWARD EARLY MONDAY MORNING. MONDAY...ONGOING WEAKER NORTHWEST FLOW LAKE EFFECT SNOWS IN THE MORNING SHOULD DECREASE IN INTENSITY WITH DEPLETING MOISTURE PROFILES AND LOWERING INVERSIONS. NAM BUFKIT PROFILES SHOW INVERSIONS LOWERING BELOW 10KFT TOWARD 18Z AS WEAK HIGH PRESSURE NOSES DOWN ACROSS THE LOWER GREAT LAKES. TEMPERATURES WILL REMAIN VERY COLD WITH HIGHS LIMITED TO THE TEENS ACROSS WNY AND SINGLE DIGITS EAST OF LAKE ONTARIO. WIND CHILLS UNDER A WEST TO NORTHWEST FLOW WILL RUN A SOLID 10 DEGREES BELOW OBSERVED SURFACE TEMPS. OUTSIDE OF THE LAKE EFFECT SOME SUNSHINE SHOULD BREAK OUT TOWARD THE AFTERNOON AS THE HIGH PRESSURE BUILDS OVERHEAD WITH MAINLY DRY BUT COLD CONDITIONS. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... TO START THIS TIME PERIOD LAKE EFFECT SNOW WILL LIKELY BE ONGOING EAST OF BOTH LAKES. AT THE SURFACE HIGH PRESSURE WILL QUICKLY PASS ACROSS THE REGION MONDAY NIGHT...AND WHILE WINDS WILL BACK SOME AHEAD OF THE AREA OF HIGH PRESSURE SENDING LAKE EFFECT SNOW NORTHWARD...INCREASING WIND SHEAR AND BRIEF PASSAGE OF DRIER AIR WILL QUICKLY ERODE AWAY THE SNOW BANDS. THE 12Z OPERATIONAL MODEL RUNS ARE COMING INTO BETTER ALIGNMENT WITH A STRENGTHENING RIDGE OF HIGH PRESSURE OVER THE WEST...WITH SEVERAL SHORTWAVES DIVING SOUTHWARD ACROSS THE GREAT LAKES REGION. EACH OF THESE WAVES OF LOW PRESSURE WILL LIKELY BRING A BURST OF SNOW TO THE REGION...GENERALLY SEVERAL INCHES TO LOW END ADVISORY LEVEL SNOWS...WITH THE FIRST WAVE ARRIVING LATER MONDAY NIGHT. WEAK ISENTROPIC UPGLIDE AHEAD OF THE SHORTWAVE...COMBINED WITH DIFFLUENT FLOW AHEAD OF THE SHORTWAVE PROMOTING VERTICAL UPLIFT SHOULD BRING A LIGHT SNOW TO WESTERN NEW YORK OVERNIGHT...AND REACHING EASTERN ZONES LATE MONDAY NIGHT OR EARLY TUESDAY. BEHIND THE FIRST SHORTWAVE TROUGH A SHORTWAVE RIDGE WILL CROSS THE REGION TUESDAY WITH PRECIPITATION CHANCES TRENDING DOWN WITH THE LOSS OF UPWARD MOTION. HOWEVER THE NEXT SHORTWAVE WILL ARRIVE TUESDAY NIGHT WITH ANOTHER ROUND OF LIGHT SNOW ACROSS THE REGION. ON WEDNESDAY NORTHWEST FLOW WILL CONTINUE ALOFT...WHILE HIGH PRESSURE AT THE SURFACE CENTERED OVER THE TENNESSEE VALLEY WILL BRING MORE OF A WEST TO EAST FLOW ACROSS THE GREAT LAKES. TEMPERATURES AT 850 HPA WILL BE JUST COLD ENOUGH TO PROMOTE INSTABILITY FOR ANOTHER ROUND OF LAKE EFFECT SNOWS...WITH THE LAKES NOW COOLED DOWN TO AROUND +2C ON ERIE AND +3-4C ON LAKE ONTARIO. FALLING LAKE INDUCED EQUILIBRIUM LEVELS AND LOWERING INVERSION HEIGHTS THROUGH THE DAY WILL NOT MAKE FOR AN IDEAL LAKE EFFECT SNOW SET UP THAT WE SAW LAST WEEK. STILL SEVERAL ADDITIONAL INCHES OF SNOW ARE POSSIBLE THROUGH THE DAY WEDNESDAY...TAPERING OFF WEDNESDAY NIGHT. OUTSIDE OF THESE LAKE BANDS SOME SUNSHINE IS POSSIBLE. TEMPERATURES WILL LIKELY REMAIN JUST BELOW NORMAL THROUGH THE TIME PERIOD...AND NOT AS COLD AS IN PRIOR DAYS. && .LONG TERM /THURSDAY THROUGH SUNDAY/... A BRIEF PATTERN CHANGE WILL EVOLVE THIS TIME PERIOD AS A LONG WAVE TROUGH FLATTENS THE WESTERN US RIDGE. IN RESPONSE DOWNSTREAM A RIDGE OF HIGH PRESSURE WILL DEVELOP ACROSS THE EAST COAST...THOUGH THE COLD POLAR LOW DROPPING SOUTHWARD TO HUDSON BAY WILL LIKELY RESTRICT THE AMPLIFICATION OF THE RIDGE. THIS WILL BRING SOME WARMING TEMPERATURES TO THE AREA TO START THE TIME PERIOD. MODELS ARE STILL SHOWING SOME INCONSISTENCIES WITH THE TIMING OF THE EJECTION OF THE CUT OFF LOW OVER THE DESERT SOUTHWEST. THIS CUT OFF LOW OVER THE SOUTHWEST WILL EVENTUALLY EJECT FROM THE SOUTHWEST AND LIKELY INTERACT WITH THE NORTHERN BRANCH OF THE JET STREAM. WILL BRING SOME CHANCE POPS ACROSS THE REGION FOR NEXT WEEKEND AS SHORTWAVES WITHIN THE NORTHERN BRANCH OF THE JET STREAM CROSS THE AREA. WITH THE 12Z MODELS BACKING OFF ON THE TIMING OF THE EJECTION OF THE DESERT CUT OFF LOW...A DEEPER LOW POSING A LARGER STORM SYSTEM MAY NOT REACH THE AREA UNTIL THE BEGINNING OF NEXT WEEK. && .AVIATION /05Z MONDAY THROUGH FRIDAY/... LAKE EFFECT SNOWS OFF LAKE ERIE IS NOW STEAMING EAST ACROSS THE SOUTHERN TIER WITH IFR CONDITIONS AT KJHW. LAKE EFFECT WILL CONTINUE BUT IN AN MUCH WEAKENED STATE THROUGH THE OVERNIGHT EVENTUALLY TAPERING OFF MONDAY MORNING. NORTH OF THIS LAKE EFFECT VFR IS ONGOING AND WILL CONTINUE THROUGH MONDAY AT KBUF/KIAG/KROC. EAST OF LAKE ONTARIO AN INTENSE BAND OF LAKE EFFECT IS OBSERVED BETWEEN KART AND KSYR. THE NORTHERN EDGE IS IMPACTING KART WITH IFR CONDITIONS. LATER TONIGHT THIS BAND WILL SHIFT SOUTH TOWARD KSYR AND KFZY WITH KART BECOMING VFR AGAIN. LAKE SNOWS WILL CONTINUE UNDER A NORTHWEST FLOW THROUGH MONDAY MORNING THEN BEGIN TO TAPER OFF AS HIGH PRESSURE BUILD OVERHEAD MONDAY AFTERNOON. OUTLOOK... MONDAY NIGHT...MAINLY VFR. TUESDAY...SNOW SHOWERS LIKELY WITH AREAS OF MVFR/IFR. WEDNESDAY...MAINLY VFR WITH A CHANCE OF SNOW SHOWERS...EXCEPT LAKE EFFECT SNOW SHOWERS LIKELY SOUTHEAST OF THE LAKES WITH LOCAL IFR. THURSDAY AND FRIDAY...MAINLY VFR. && .MARINE... BRISK WESTERLY WINDS ACROSS THE LAKE IS RESULTING IN A PERIOD OF HIGH END ADVISORY LEVEL WINDS AND WAVES ON BOTH LAKES TONIGHT LASTING INTO MONDAY BEFORE HIGH PRESSURE BUILDS OVER THE REGION ALONG WITH DIMINISHING WINDS. A CLIPPER SYSTEM WILL DROP SOUTH ACROSS THE LAKES ON TUESDAY. WINDS AND WAVES WILL INCREASE AGAIN TUESDAY NIGHT INTO WEDNESDAY BEHIND THIS PASSING CLIPPER SYSTEM. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...LAKE EFFECT SNOW WARNING UNTIL 5 AM EST EARLY THIS MORNING FOR NYZ007-008. LAKE EFFECT SNOW WARNING UNTIL 4 PM EST THIS AFTERNOON FOR NYZ006. LAKE EFFECT SNOW ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR NYZ004-005. LAKE EFFECT SNOW WARNING UNTIL 10 AM EST THIS MORNING FOR NYZ019-020. LAKE EFFECT SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR NYZ021. MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR LEZ040- 041. SMALL CRAFT ADVISORY UNTIL 3 AM EST EARLY THIS MORNING FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR LOZ043>045. SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR LOZ042. && $$ SYNOPSIS...SMITH NEAR TERM...SMITH SHORT TERM...THOMAS LONG TERM...THOMAS AVIATION...SMITH MARINE...SMITH/TMA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
334 PM CST MON DEC 16 2013 .SHORT TERM...(THIS AFTERNOON THROUGH TUESDAY AFTERNOON) ISSUED AT 334 PM CST MON DEC 16 2013 FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE AREAS OF BLOWING/DRIFTING SNOW RESULTING IN POSSIBLE ICY ROADS/BLACK ICE ACROSS THE NORTH THROUGH THIS EVENING...AND A CHANCE OF LIGHT SNOW THIS AFTERNOON AND EVENING WEST TO EAST. CURRENTLY...STRONG NORTHWEST FLOW ALOFT WITH A SHARP RIDGE OFF THE WEST COAST AND A BROAD LONG WAVE TROUGH OVER THE EASTERN UNITED STATES. UPPER LEVEL JET STREAM EXTENDS FROM THE TOP OF THE RIDGE OVER ALASKA...SOUTHEAST INTO THE NORTHERN HIGH PLAINS OF MT/WY. STRONG PRESSURE GRADIENT CONTINUES TO DEVELOP ACROSS WEST AND CENTRAL NORTH DAKOTA WEST OF A SURFACE TROUGH OVER FAR WESTERN MINNESOTA. GRADIENT FORCING WILL INCREASE THROUGHOUT THE DAY AND INTO THIS EVENING AS THE TROUGH REMAINS QUASI-STATIONARY AND AS A SURFACE HIGH BUILDS OFF TO OUR WEST CENTERED OVER THE NORTHEASTERN SNAKE RIVER VALLEY OF EASTERN IDAHO. MODELS EARLIER WERE LOOKING LIKE THEY WERE TRENDING TOWARDS A CONSENSUS REGARDING PRECIPITATION CHANCES THIS AFTERNOON AND EVENING. NOW NOT SO MUCH. MOISTURE IS HAVING A HARD TIME REACHING THE GROUND ACROSS MY WEST CENTRAL. WEB CAMS OVER SOUTHWEST NORTH DAKOTA DEFINITELY SHOWING SNOWFALL ALTHOUGH MOSTLY MELTING ON THE ROAD SURFACES. BOWMAN RADAR STILL LIT UP...AND BAKER MT STILL REPORTING SNOW. THE 12Z ECMWF AND LATEST RAP SEEM TO BE CAPTURING REALITY THE BEST VERSUS OTHER GUIDANCE. LEANED IN THEIR DIRECTION WITH LINGERING LIGHT PRECIPITATION SOUTHWEST NOW THROUGH THIS EVENING...AND ANOTHER AREA OF LIGHT PRECIPITATION MOVING SOUTHEAST OVER MY EASTERN COUNTIES LATE AFTERNOON AND EVENING. THIS AREA CURRENTLY SHOWING UP ON RADAR OVER SOUTHEAST SK/SOUTHWEST MANITOBA. THE INCREASING PRESSURE GRADIENT WILL SEE WINDS INCREASE TO JUST BELOW WIND ADVISORY CRITERIA MOST LOCATIONS NOW THROUGH THE EVENING HOURS...BEFORE WINDING DOWN AFTER 06Z. AT THIS TIME WINDS ARE SUSTAINED AT 15-25 MPH MOST LOCATIONS...WITH GUSTS AS HIGH AS 35 MPH REPORTED. ROAD SFC TEMPS REMAIN AT OR BELOW FREEZING NORTH AND ABOVE 32F SOUTH. AIR TEMPERATURES MAINLY IN THE LOWER TO MID 30S. WIND DRIVEN SNOW IS STILL EXPECTED TO CREATE HAZARDOUS TRAVEL...ESPECIALLY WHEN WET ROADS REFREEZE AND/OR BLOWING SNOW STARTS TO STICK THIS AFTERNOON. WILL MAINTAIN THE SPECIAL WEATHER STATEMENT AS IS FOR NOW AND LET THE EVENING CREW DECIDE ITS FATE AT THE 7PM UPDATE PERIOD. TUESDAY MORNING/AFTERNOON LOOK TO BE RELATIVELY QUIET WITH PARTLY CLOUDY SKIES AND DRY CONDITIONS. A WARM FRONT MOVING INTO SOUTHEAST MONTANA WILL SEE TEMPERATURES WARMING TO NEAR 40 OVER MY FAR SOUTHWEST CORNER. SHARP TEMPERATURE GRADIENT WITH HIGHS AROUND 15 ABOVE FOR THE TURTLE MOUNTAINS. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 334 PM CST MON DEC 16 2013 THE MAIN FORECAST ISSUE IS SNOWFALL AMOUNTS AND COVERAGE WITH THE MID WEEK STORM. A LOW PRESSURE CLIPPER SYSTEM IS FORECAST TO DEVELOP TUESDAY OVER ALBERTA AND MOVE EAST/SOUTHEAST TOWARDS NORTH DAKOTA TUESDAY NIGHT. WINDS ACROSS THE FORECAST AREA SHOULD START OUT SOUTHERLY EARLY TUESDAY EVENING...BECOMING WEST DURING THE EVENING/NIGHT WITH WARM ADVECTION AS NORTH DAKOTA REMAINS IN THE WARM SECTOR OF THE SYSTEM. ON WEDNESDAY THE CLIPPER LOW DEVELOPS INTO MORE OF A COLD FRONT IN NATURE...MOVING SOUTH ACROSS THE STATE. IT APPEARS THAT THE MARKED COLD ADVECTION WITH THE ARCTIC AIR BEGINS WEDNESDAY AROUND NOON IN THE NORTH AND DURING THE AFTERNOON FARTHER SOUTH. HIGHS WEDNESDAY SHOULD RANGE FROM THE UPPER TEENS/MID 20S NORTH TO THE UPPER 20S/30S SOUTH. KEPT A SLIGHT CHANCE OF LIGHT SNOW IN THE NORTHWEST AND NORTH CENTRAL NORTH DAKOTA ALONG THE ARCTIC COLD FRONT. MODEL AGREEMENT CONTINUES TO IMPROVE REGARDING THE MAIN SYNOPTIC FEATURES OF THE UPPER LEVEL TROUGH AND VORT ENERGY IMPULSES...AS WELL AS THE POSITION OF THE COLD FRONT AND ARCTIC HIGH PRESSURE SYSTEM. THE UPPER LEVEL TROUGH MOVES ACROSS NORTH DAKOTA THURSDAY/THURSDAY EVENING. MEANWHILE THE SURFACE ARCTIC HIGH DIVES SOUTH FROM ALBERTA INTO MONTANA WEDNESDAY NIGHT/THURSDAY. IN NORTH DAKOTA...THE ARCTIC COLD FRONT MOVES SOUTH ACROSS THE STATE WEDNESDAY AFTERNOON/EVENING WITH COLD ADVECTION CONTINUING THROUGH THE DAY THURSDAY. THE PLACEMENT OF SNOWFALL LOOKS TO BE HIGHEST IN MONTANA...BUT SNOW ACCUMULATIONS ALONG THE NORTH DAKOTA/SOUTH DAKOTA BORDER SHOULD BE IN THE 2-4 INCH RANGE. FOR WESTERN AND CENTRAL NORTH DAKOTA THE BULK OF THE SNOWFALL SHOULD BEGIN WEDNESDAY NIGHT IN THE WEST...AND EXPAND INTO CENTRAL NORTH DAKOTA AFTER MIDNIGHT WEDNESDAY NIGHT/DAYBREAK THURSDAY MORNING...CONTINUE FOR MUCH OF THE DAY THURSDAY...BEFORE TAPERING OFF IN THE JAMES RIVER VALLEY THURSDAY EVENING. VERY COLD AIR WILL ACCOMPANY THIS STORM SYSTEM WEDNESDAY NIGHT THROUGH SATURDAY. SOME AREAS...ESPECIALLY THE NORTH...MAY HIT WIND CHILL ADVISORY CRITERIA WEDNESDAY NIGHT AND THURSDAY NIGHT. THE UPPER LEVEL PATTERN THROUGH THE WEEKEND CONTINUES NORTHWEST FLOW ALOFT WITH A LARGE HUDSON BAY LOW IN PLACE. TOWARDS THE BEGINNING OF NEXT WEEK THE MODELS ARE HINTING AT A MORE PROGRESSIVE PATTERN WITH A WESTERN RIDGE BUILDING AND PUSHING THE HUDSON BAY LOW EASTWARD. NO BIG WARM-UPS BUT NO BIG ARCTIC OUTBREAKS EITHER. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING) ISSUED AT 334 PM CST MON DEC 16 2013 MAINLY VFR CIGS/VSBYS EXPECTED NEXT 24HR. BKN/OVC CIGS BETWEEN 5KFT AND 10KFT WITH GUSTY WEST-NORTHWESTERLY WINDS OF 20KT TO 30KT WILL DOMINATE MOST OF THE AERODROMES TODAY AND THIS EVENING. BLOWING/DRIFTING SNOW IS POSSIBLE BUT NOT EXPECTED TO AFFECT VISIBILITIES BELOW VFR AT THIS TIME. A VCSH AND A TEMPO GROUP WILL BE MAINTAINED FOR KDIK AND KJMS. SHOULD REMAIN MAINLY DRY OTHER TERMINALS. EXPECT SCT CLOUDS TO SKC AFTER 06Z TUESDAY WITH BRISK WINDS OF 15KT CONTINUING THROUGH 12Z TUESDAY. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...NH LONG TERM...JV AVIATION...NH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
100 PM CST MON DEC 16 2013 .UPDATE... ISSUED AT 100 PM CST MON DEC 16 2013 STRONG NORTHWEST FLOW ALOFT WITH A RIDGE OFF THE WEST COAST AND A BROAD TROUGH OVER THE EASTERN CONUS. UPPER LEVEL JET STREAM EXTENDS FROM ALASKA SOUTHEAST INTO THE NORTHERN HIGH PLAINS. STRONG PRESSURE GRADIENT TAKING SHAPE ACROSS WEST AND CENTRAL NORTH DAKOTA WEST OF A SURFACE TROUGH NEAR THE RED RIVER VALLEY. GRADIENT FORCING WILL INCREASE THROUGHOUT THE DAY AND INTO THIS EVENING AS THE TROUGH REMAINS QUASI-STATIONARY AND AS A SURFACE HIGH BUILDS OFF TO OUR WEST CENTERED OVER THE NORTHEASTERN SNAKE RIVER VALLEY OF EASTERN IDAHO. MODELS ARE STARTING TO SHOW THEIR CARDS REGARDING PRECIPITATION CHANCES THIS AFTERNOON AND EVENING. DECENT AREA OF RADAR ECHOS COVER MOST OF NORTHEASTERN MONTANA. LATEST NAM AND 4KM WRF ARE DEPICTING THIS RATHER WELL. LEANED ON THEIR GUIDANCE IN BRINGING THIS AREA OF PRECIPITATION EAST ACROSS WEST AND CENTRAL NORTH DAKOTA THROUGH THIS AFTERNOON AND EARLY EVENING AS UPPER LEVEL DIVERGENCE IN THE LEFT EXIT REGION OF THE UPPER JET OVERSPREADS THE NORTHERN PLAINS. EMBEDDED MID LEVEL IMPULSE WILL ALSO AID IN PRECIPITATION DEVELOPMENT. AT THIS TIME EXPECT QPF TO BE LIGHT WITH MAYBE UP TO HALF AN INCH OF SNOWFALL POSSIBLE. WITH THE INCREASING PRESSURE GRADIENT MENTIONED ABOVE...WILL SEE WINDS INCREASE TO JUST BELOW WIND ADVISORY CRITERIA THIS AFTERNOON MOST LOCATIONS...THEN MORE CENTRAL AND EAST THIS EVENING BEFORE WINDING DOWN AFTER 06Z. AT THIS TIME WINDS ARE SUSTAINED AT 15-20 MPH MOST LOCATIONS...WITH GUSTS AS HIGH AS 30 MPH REPORTED...AND WILL ONLY INCREASE OVER THE NEXT FEW HOURS. NORTH DAKOTA DOT REPORTED FROST COVERED ROADS ACROSS CERTAIN PARTS OF THE STATE THE PAST SEVERAL HOURS...IN ADDITION TO NOW ICE COVERED ROADS NORTH WHERE ROAD SFC TEMPS REMAIN BELOW FREEZING BUT AIR TEMPERATURES HAVE WARMED TO NEAR 32F. WIND DRIVEN SNOW THUS CREATING HAZARDOUS TRAVEL. EXPECT TRAVEL PROBLEMS TO ONLY INCREASE FOR THE REMAINDER OF THE AFTERNOON AND EVENING. WILL MAINTAIN THE SPECIAL WEATHER STATEMENT AS IS FOR NOW. MAY NEED TO CONSIDER EXPANDING DEPENDING ON HOW WARM WE WILL GET...ANY REPORTS FROM THE DOT OR LAW ENFORCEMENT...AND HOW MUCH SNOW MAY FALL THROUGH EARLY TO MID EVENING. UPDATE ISSUED AT 1007 AM CST MON DEC 16 2013 HOURLY WEATHER ELEMENTS WERE UPDATED BASED ON LATEST OBSERVATIONS. DID NOT CHANGE OUR FORECAST HIGHS MUCH FROM WHAT WAS INHERITED. MAIN UPDATE WAS TO INCREASE POPS SOUTHWEST THIS MORNING WITH BAKER MT REPORTING LIGHT SNOW AND THE BOWMAN RADAR LIT UP PRETTY GOOD OVER MY FAR SOUTHWEST CORNER. UPDATE ISSUED AT 642 AM CST MON DEC 16 2013 UPDATE FOR EARLY MORNING TEMPERATURE TRENDS AND TO INCREASE POPS NORTH AND EAST THIS AFTERNOON. LATEST TRENDS AND HI-RES MODEL RUNS INDICATE LITTLE OR NO THREAT FOR FREEZING RAIN/SLEET WITH P-TYPE EXPECTED TO BE ALL SNOW OR POSSIBLE RAIN/SNOW MIX THIS AFTERNOON IN LOCATIONS WITH WARMER SURFACE TEMPS. LATEST EARLY MORNING MODEL RUNS INCLUDING THE 06Z WRF AND 11Z RAP ARE ALSO INSISTENT ON AN AREA OF LIGHT SNOW TRACKING OVER THE NORTHERN AND EASTERN PORTIONS OF THE FORECAST AREA THIS AFTERNOON. HAVE INCREASED POPS DURING THE AFTERNOON. THE LIGHT SNOW MAY ADD TO THE TRAVEL HAZARDS...IN THE FORM OF BRIEF REDUCED VISIBILITY...AS WINDS GUST TO 35 MPH. THIS IS IN ADDITION TO THE THREAT OF EXISTING SNOW BLOWING ACROSS ROADS...MELTING...THEN RE-FREEZING. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 315 AM CST MON DEC 16 2013 MAIN HIGHLIGHTS WILL BE AREAS OF BLOWING/DRIFTING SNOW WITH ICY ROADS/BLACK ICE POSSIBLY DEVELOPING MONDAY AFTERNOON NORTH...AND A SLIGHT CHANCE OF MIXED PRECIPITATION THIS AFTERNOON AS ANOTHER SHORTWAVE TRAVERSES THROUGH. THE LATEST WATER VAPOR IMAGERY SHOWS TWO SHORTWAVES OF INTEREST. THE FIRST WAS LOCATED NEAR LAKE WINNIPEG MOVING SOUTHEAST WITH TIME. LOCAL AND REGIONAL RADAR WAS SHOWING AN AREA OF LIGHT SNOW FROM NORTHEAST MONTANA...ACROSS NORTHWEST AND INTO NORTH CENTRAL NORTH DAKOTA. THIS SHORTWAVE IS ALSO INTERACTING WITH A SURFACE WARM FRONT LOCATED FROM NEAR SHERWOOD...TO MINOT...AND SOUTH TO GLEN ULLIN AND THEN SNAKING INTO PIERRE SOUTH DAKOTA. MINOT DUAL POL RADAR SHOWS SOME POTENTIAL FOR AN ELEVATED MELTING LAYER AND POSSIBLY MIXED PRECIPITATION. THE RAP13 WAS INDICATING THAT LIGHT SNOW WOULD MAINLY DOMINATE THE PRECIPITATION BAND WITH THE POSSIBILITY OF LIGHT FREEZING RAIN ON THE BACK EDGE. WILL CONTINUE WITH THIS THINKING EARLY THIS MORNING. THE SECOND SHORTWAVE WAS LOCATED IN EAST CENTRAL ALBERTA...WHICH IS FORECAST TO SHIFT INTO MOHALL BY 00Z TUESDAY. THE LEFT EXIT REGION OF A 140KT H3 JET WILL CREATE ENOUGH LIFT TO PRODUCE A SLIGHT CHC OF MIXED PRECIPITATION FOR THE NORTH THIS AFTERNOON. MOST TEMPERATURES WILL WARM ABOVE FREEZING FROM WEST TO EAST TODAY AS THE WARM FRONT CONTINUES TO ADVANCE EAST. THE MAIN ISSUE THIS AFTERNOON WILL BE BRISK WESTERLY WINDS OF 20 TO 30 MPH CREATING BLOWING/DRIFTING SNOW ACROSS THE HIGHWAYS WITH POSSIBLE BLACK ICE FORMING. A SPECIAL WEATHER STATEMENT WAS ISSUED HIGHLIGHTING THE POTENTIAL FOR BLOWING AND DRIFTING SNOW...MELTING...AND THEN REFREEZING ACROSS THE NORTH. GIVEN SUCCESSIVE ROUNDS OF LIGHT SNOW THE LAST FEW DAYS...BRISK WINDS...AND AFTERNOON TEMPERATURES HOVERING AROUND FREEZING...THIS AREA WILL BE IN LINE FOR THE BLOWING/DRIFTING/MELTING/REFREEZING PROCESSES. FARTHER SOUTH AND WEST WHERE TEMPERATURES WILL BE IN THE UPPER 30S...EXPECT ICY TRAVEL TO DEVELOP TONIGHT ONCE WE FALL BELOW FREEZING AFTER SUNSET. AFTERNOON HIGHS TODAY WILL RANGE FROM THE UPPER 20S IN THE TURTLE MOUNTAINS TO THE UPPER 30S WEST. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 315 AM CST MON DEC 16 2013 THE MAIN FORECAST ISSUE IS SNOWFALL AMOUNTS AND COVERAGE WITH THE MID WEEK STORM. ON TUESDAY...COLDER AIR WILL BEGIN TO GRADUALLY SAG INTO NORTHEAST NORTH DAKOTA WITH HIGHS EXPECTED TO ONLY REACH THE TEENS. MILD WEATHER WILL CONTINUE IN THE SOUTHWEST WITH HIGHS IN THE 30S LIKELY. MODEL AGREEMENT IS IMPROVING REGARDING THE NORTHERN STREAM TROUGH THAT WILL IMPACT THE STATE WEDNESDAY NIGHT INTO THURSDAY. THE SOUTHERN HALF OF THE FORECAST AREA...PARTICULARLY ALONG AND SOUTH OF THE INTERSTATE 94 CORRIDOR...IS STILL FAVORED FOR THE HIGHER SNOWFALL AMOUNTS. MODEL QPF GENERALLY RANGES FROM 0.2 TO AROUND 0.3 INCHES. WITH RELATIVELY CONSERVATIVE SNOW TO LIQUID RATIOS NEAR OR BELOW 20 TO 1...THAT WOULD RESULT IN GENERAL 4 TO 6 INCH SNOWFALL AMOUNTS. HOWEVER...WITH THE INCREASINGLY COLD THERMAL PROFILE AND POTENTIAL FOR NARROW BANDS OF ENHANCED LIFT...WE COULD EASILY SEE PERIODS OF HIGHER RATIOS...WHICH WOULD PUSH SNOWFALL AMOUNTS OVER WARNING CRITERIA SOME AREAS. PLENTY COULD CHANGE OVER THE NEXT 2 TO 3 DAYS...BUT THE POTENTIAL IS THERE. VERY COLD AIR WILL ACCOMPANY THE TROUGH WEDNESDAY NIGHT THROUGH SATURDAY. SOME AREAS...ESPECIALLY THE NORTH...MAY HIT WIND CHILL ADVISORY CRITERIA WEDNESDAY AND THURSDAY NIGHTS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 100 PM CST MON DEC 16 2013 MAINLY VFR CIGS/VSBYS EXPECTED NEXT 24HR. BKN/OVC CIGS BETWEEN 5KFT AND 10KFT WITH GUSTY WEST-NORTHWESTERLY WINDS OF 20KT TO 30KT WILL DOMINATE MOST OF THE AERODROMES TODAY. BLOWING/DRIFTING SNOW IS POSSIBLE BUT NOT EXPECTED TO AFFECT VISIBILITIES BELOW VFR AT THIS TIME. A VCSH AND A TEMPO GROUP HAS BEEN ADDED ALL LOCATIONS THIS AFTERNOON THROUGH MID EVENING AS AN AREA OF SNOW IS EXPECTED TO MOVE EAST ACROSS NORTH DAKOTA OVER THE NEXT SEVERAL HOURS...POSSIBLY ACCOMPANIED BY A BRIEF MVFR CIG AND/OR VIS. EXPECT SCT CLOUDS TO SKC AFTER 06Z TUESDAY WITH BRISK WINDS OF 15KT CONTINUING THROUGH 12Z TUESDAY. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...NH SHORT TERM...KS LONG TERM...RK AVIATION...NH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1007 AM CST MON DEC 16 2013 .UPDATE... ISSUED AT 1007 AM CST MON DEC 16 2013 HOURLY WEATHER ELEMENTS WERE UPDATED BASED ON LATEST OBSERVATIONS. DID NOT CHANGE OUR FORECAST HIGHS MUCH FROM WHAT WAS INHERITED. MAIN UPDATE WAS TO INCREASE POPS SOUTHWEST THIS MORNING WITH BAKER MT REPORTING LIGHT SNOW AND THE BOWMAN RADAR LIT UP PRETTY GOOD OVER MY FAR SOUTHWEST CORNER. UPDATE ISSUED AT 642 AM CST MON DEC 16 2013 UPDATE FOR EARLY MORNING TEMPERATURE TRENDS AND TO INCREASE POPS NORTH AND EAST THIS AFTERNOON. LATEST TRENDS AND HI-RES MODEL RUNS INDICATE LITTLE OR NO THREAT FOR FREEZING RAIN/SLEET WITH P-TYPE EXPECTED TO BE ALL SNOW OR POSSIBLE RAIN/SNOW MIX THIS AFTERNOON IN LOCATIONS WITH WARMER SURFACE TEMPS. LATEST EARLY MORNING MODEL RUNS INCLUDING THE 06Z WRF AND 11Z RAP ARE ALSO INSISTENT ON AN AREA OF LIGHT SNOW TRACKING OVER THE NORTHERN AND EASTERN PORTIONS OF THE FORECAST AREA THIS AFTERNOON. HAVE INCREASED POPS DURING THE AFTERNOON. THE LIGHT SNOW MAY ADD TO THE TRAVEL HAZARDS...IN THE FORM OF BRIEF REDUCED VISIBILITY...AS WINDS GUST TO 35 MPH. THIS IS IN ADDITION TO THE THREAT OF EXISTING SNOW BLOWING ACROSS ROADS...MELTING...THEN RE-FREEZING. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 315 AM CST MON DEC 16 2013 MAIN HIGHLIGHTS WILL BE AREAS OF BLOWING/DRIFTING SNOW WITH ICY ROADS/BLACK ICE POSSIBLY DEVELOPING MONDAY AFTERNOON NORTH...AND A SLIGHT CHANCE OF MIXED PRECIPITATION THIS AFTERNOON AS ANOTHER SHORTWAVE TRAVERSES THROUGH. THE LATEST WATER VAPOR IMAGERY SHOWS TWO SHORTWAVES OF INTEREST. THE FIRST WAS LOCATED NEAR LAKE WINNIPEG MOVING SOUTHEAST WITH TIME. LOCAL AND REGIONAL RADAR WAS SHOWING AN AREA OF LIGHT SNOW FROM NORTHEAST MONTANA...ACROSS NORTHWEST AND INTO NORTH CENTRAL NORTH DAKOTA. THIS SHORTWAVE IS ALSO INTERACTING WITH A SURFACE WARM FRONT LOCATED FROM NEAR SHERWOOD...TO MINOT...AND SOUTH TO GLEN ULLIN AND THEN SNAKING INTO PIERRE SOUTH DAKOTA. MINOT DUAL POL RADAR SHOWS SOME POTENTIAL FOR AN ELEVATED MELTING LAYER AND POSSIBLY MIXED PRECIPITATION. THE RAP13 WAS INDICATING THAT LIGHT SNOW WOULD MAINLY DOMINATE THE PRECIPITATION BAND WITH THE POSSIBILITY OF LIGHT FREEZING RAIN ON THE BACK EDGE. WILL CONTINUE WITH THIS THINKING EARLY THIS MORNING. THE SECOND SHORTWAVE WAS LOCATED IN EAST CENTRAL ALBERTA...WHICH IS FORECAST TO SHIFT INTO MOHALL BY 00Z TUESDAY. THE LEFT EXIT REGION OF A 140KT H3 JET WILL CREATE ENOUGH LIFT TO PRODUCE A SLIGHT CHC OF MIXED PRECIPITATION FOR THE NORTH THIS AFTERNOON. MOST TEMPERATURES WILL WARM ABOVE FREEZING FROM WEST TO EAST TODAY AS THE WARM FRONT CONTINUES TO ADVANCE EAST. THE MAIN ISSUE THIS AFTERNOON WILL BE BRISK WESTERLY WINDS OF 20 TO 30 MPH CREATING BLOWING/DRIFTING SNOW ACROSS THE HIGHWAYS WITH POSSIBLE BLACK ICE FORMING. A SPECIAL WEATHER STATEMENT WAS ISSUED HIGHLIGHTING THE POTENTIAL FOR BLOWING AND DRIFTING SNOW...MELTING...AND THEN REFREEZING ACROSS THE NORTH. GIVEN SUCCESSIVE ROUNDS OF LIGHT SNOW THE LAST FEW DAYS...BRISK WINDS...AND AFTERNOON TEMPERATURES HOVERING AROUND FREEZING...THIS AREA WILL BE IN LINE FOR THE BLOWING/DRIFTING/MELTING/REFREEZING PROCESSES. FARTHER SOUTH AND WEST WHERE TEMPERATURES WILL BE IN THE UPPER 30S...EXPECT ICY TRAVEL TO DEVELOP TONIGHT ONCE WE FALL BELOW FREEZING AFTER SUNSET. AFTERNOON HIGHS TODAY WILL RANGE FROM THE UPPER 20S IN THE TURTLE MOUNTAINS TO THE UPPER 30S WEST. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 315 AM CST MON DEC 16 2013 THE MAIN FORECAST ISSUE IS SNOWFALL AMOUNTS AND COVERAGE WITH THE MID WEEK STORM. ON TUESDAY...COLDER AIR WILL BEGIN TO GRADUALLY SAG INTO NORTHEAST NORTH DAKOTA WITH HIGHS EXPECTED TO ONLY REACH THE TEENS. MILD WEATHER WILL CONTINUE IN THE SOUTHWEST WITH HIGHS IN THE 30S LIKELY. MODEL AGREEMENT IS IMPROVING REGARDING THE NORTHERN STREAM TROUGH THAT WILL IMPACT THE STATE WEDNESDAY NIGHT INTO THURSDAY. THE SOUTHERN HALF OF THE FORECAST AREA...PARTICULARLY ALONG AND SOUTH OF THE INTERSTATE 94 CORRIDOR...IS STILL FAVORED FOR THE HIGHER SNOWFALL AMOUNTS. MODEL QPF GENERALLY RANGES FROM 0.2 TO AROUND 0.3 INCHES. WITH RELATIVELY CONSERVATIVE SNOW TO LIQUID RATIOS NEAR OR BELOW 20 TO 1...THAT WOULD RESULT IN GENERAL 4 TO 6 INCH SNOWFALL AMOUNTS. HOWEVER...WITH THE INCREASINGLY COLD THERMAL PROFILE AND POTENTIAL FOR NARROW BANDS OF ENHANCED LIFT...WE COULD EASILY SEE PERIODS OF HIGHER RATIOS...WHICH WOULD PUSH SNOWFALL AMOUNTS OVER WARNING CRITERIA SOME AREAS. PLENTY COULD CHANGE OVER THE NEXT 2 TO 3 DAYS...BUT THE POTENTIAL IS THERE. VERY COLD AIR WILL ACCOMPANY THE TROUGH WEDNESDAY NIGHT THROUGH SATURDAY. SOME AREAS...ESPECIALLY THE NORTH...MAY HIT WIND CHILL ADVISORY CRITERIA WEDNESDAY AND THURSDAY NIGHTS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 642 AM CST MON DEC 16 2013 VFR CIGS/VSBYS CAN BE EXPECTED NEXT 24HR. BKN/OVC CIGS BETWEEN 5KFT AND 10KFT WITH GUSTY WEST-NORTHWESTERLY WINDS OF 20KT TO 30KT WILL DOMINATE MOST OF THE AERODROMES. BLOWING/DRIFTING SNOW IS POSSIBLE BUT NOT EXPECTED TO AFFECT VISIBILITIES BELOW VFR AT THIS TIME. A VCSH HAS BEEN ADDED TO KISN/KMOT/KJMS MONDAY AFTERNOON AS AN UPPER LEVEL DISTURBANCE TRACKS ACROSS NORTHERN AND CENTRAL NORTH DAKOTA. EXPECT SCT CLOUDS TO SKC AFTER 00Z TUESDAY WITH BRISK WINDS OF 15KT CONTINUING THROUGH 12Z TUESDAY. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...NH SHORT TERM...KS LONG TERM...RK AVIATION...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
649 AM CST MON DEC 16 2013 .UPDATE... ISSUED AT 642 AM CST MON DEC 16 2013 UPDATE FOR EARLY MORNING TEMPERATURE TRENDS AND TO INCREASE POPS NORTH AND EAST THIS AFTERNOON. LATEST TRENDS AND HI-RES MODEL RUNS INDICATE LITTLE OR NO THREAT FOR FREEZING RAIN/SLEET WITH P-TYPE EXPECTED TO BE ALL SNOW OR POSSIBLE RAIN/SNOW MIX THIS AFTERNOON IN LOCATIONS WITH WARMER SURFACE TEMPS. LATEST EARLY MORNING MODEL RUNS INCLUDING THE 06Z WRF AND 11Z RAP ARE ALSO INSISTENT ON AN AREA OF LIGHT SNOW TRACKING OVER THE NORTHERN AND EASTERN PORTIONS OF THE FORECAST AREA THIS AFTERNOON. HAVE INCREASED POPS DURING THE AFTERNOON. THE LIGHT SNOW MAY ADD TO THE TRAVEL HAZARDS...IN THE FORM OF BRIEF REDUCED VISIBILITY...AS WINDS GUST TO 35 MPH. THIS IS IN ADDITION TO THE THREAT OF EXISTING SNOW BLOWING ACROSS ROADS...MELTING...THEN RE-FREEZING. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 315 AM CST MON DEC 16 2013 MAIN HIGHLIGHTS WILL BE AREAS OF BLOWING/DRIFTING SNOW WITH ICY ROADS/BLACK ICE POSSIBLY DEVELOPING MONDAY AFTERNOON NORTH...AND A SLIGHT CHANCE OF MIXED PRECIPITATION THIS AFTERNOON AS ANOTHER SHORTWAVE TRAVERSES THROUGH. THE LATEST WATER VAPOR IMAGERY SHOWS TWO SHORTWAVES OF INTEREST. THE FIRST WAS LOCATED NEAR LAKE WINNIPEG MOVING SOUTHEAST WITH TIME. LOCAL AND REGIONAL RADAR WAS SHOWING AN AREA OF LIGHT SNOW FROM NORTHEAST MONTANA...ACROSS NORTHWEST AND INTO NORTH CENTRAL NORTH DAKOTA. THIS SHORTWAVE IS ALSO INTERACTING WITH A SURFACE WARM FRONT LOCATED FROM NEAR SHERWOOD...TO MINOT...AND SOUTH TO GLEN ULLIN AND THEN SNAKING INTO PIERRE SOUTH DAKOTA. MINOT DUAL POL RADAR SHOWS SOME POTENTIAL FOR AN ELEVATED MELTING LAYER AND POSSIBLY MIXED PRECIPITATION. THE RAP13 WAS INDICATING THAT LIGHT SNOW WOULD MAINLY DOMINATE THE PRECIPITATION BAND WITH THE POSSIBILITY OF LIGHT FREEZING RAIN ON THE BACK EDGE. WILL CONTINUE WITH THIS THINKING EARLY THIS MORNING. THE SECOND SHORTWAVE WAS LOCATED IN EAST CENTRAL ALBERTA...WHICH IS FORECAST TO SHIFT INTO MOHALL BY 00Z TUESDAY. THE LEFT EXIT REGION OF A 140KT H3 JET WILL CREATE ENOUGH LIFT TO PRODUCE A SLIGHT CHC OF MIXED PRECIPITATION FOR THE NORTH THIS AFTERNOON. MOST TEMPERATURES WILL WARM ABOVE FREEZING FROM WEST TO EAST TODAY AS THE WARM FRONT CONTINUES TO ADVANCE EAST. THE MAIN ISSUE THIS AFTERNOON WILL BE BRISK WESTERLY WINDS OF 20 TO 30 MPH CREATING BLOWING/DRIFTING SNOW ACROSS THE HIGHWAYS WITH POSSIBLE BLACK ICE FORMING. A SPECIAL WEATHER STATEMENT WAS ISSUED HIGHLIGHTING THE POTENTIAL FOR BLOWING AND DRIFTING SNOW...MELTING...AND THEN REFREEZING ACROSS THE NORTH. GIVEN SUCCESSIVE ROUNDS OF LIGHT SNOW THE LAST FEW DAYS...BRISK WINDS...AND AFTERNOON TEMPERATURES HOVERING AROUND FREEZING...THIS AREA WILL BE IN LINE FOR THE BLOWING/DRIFTING/MELTING/REFREEZING PROCESSES. FARTHER SOUTH AND WEST WHERE TEMPERATURES WILL BE IN THE UPPER 30S...EXPECT ICY TRAVEL TO DEVELOP TONIGHT ONCE WE FALL BELOW FREEZING AFTER SUNSET. AFTERNOON HIGHS TODAY WILL RANGE FROM THE UPPER 20S IN THE TURTLE MOUNTAINS TO THE UPPER 30S WEST. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 315 AM CST MON DEC 16 2013 THE MAIN FORECAST ISSUE IS SNOWFALL AMOUNTS AND COVERAGE WITH THE MID WEEK STORM. ON TUESDAY...COLDER AIR WILL BEGIN TO GRADUALLY SAG INTO NORTHEAST NORTH DAKOTA WITH HIGHS EXPECTED TO ONLY REACH THE TEENS. MILD WEATHER WILL CONTINUE IN THE SOUTHWEST WITH HIGHS IN THE 30S LIKELY. MODEL AGREEMENT IS IMPROVING REGARDING THE NORTHERN STREAM TROUGH THAT WILL IMPACT THE STATE WEDNESDAY NIGHT INTO THURSDAY. THE SOUTHERN HALF OF THE FORECAST AREA...PARTICULARLY ALONG AND SOUTH OF THE INTERSTATE 94 CORRIDOR...IS STILL FAVORED FOR THE HIGHER SNOWFALL AMOUNTS. MODEL QPF GENERALLY RANGES FROM 0.2 TO AROUND 0.3 INCHES. WITH RELATIVELY CONSERVATIVE SNOW TO LIQUID RATIOS NEAR OR BELOW 20 TO 1...THAT WOULD RESULT IN GENERAL 4 TO 6 INCH SNOWFALL AMOUNTS. HOWEVER...WITH THE INCREASINGLY COLD THERMAL PROFILE AND POTENTIAL FOR NARROW BANDS OF ENHANCED LIFT...WE COULD EASILY SEE PERIODS OF HIGHER RATIOS...WHICH WOULD PUSH SNOWFALL AMOUNTS OVER WARNING CRITERIA SOME AREAS. PLENTY COULD CHANGE OVER THE NEXT 2 TO 3 DAYS...BUT THE POTENTIAL IS THERE. VERY COLD AIR WILL ACCOMPANY THE TROUGH WEDNESDAY NIGHT THROUGH SATURDAY. SOME AREAS...ESPECIALLY THE NORTH...MAY HIT WIND CHILL ADVISORY CRITERIA WEDNESDAY AND THURSDAY NIGHTS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 642 AM CST MON DEC 16 2013 VFR CIGS/VSBYS CAN BE EXPECTED NEXT 24HR. BKN/OVC CIGS BETWEEN 5KFT AND 10KFT WITH GUSTY WEST-NORTHWESTERLY WINDS OF 20KT TO 30KT WILL DOMINATE MOST OF THE AERODROMES. BLOWING/DRIFTING SNOW IS POSSIBLE BUT NOT EXPECTED TO AFFECT VISIBILITIES BELOW VFR AT THIS TIME. A VCSH HAS BEEN ADDED TO KISN/KMOT/KJMS MONDAY AFTERNOON AS AN UPPER LEVEL DISTURBANCE TRACKS ACROSS NORTHERN AND CENTRAL NORTH DAKOTA. EXPECT SCT CLOUDS TO SKC AFTER 00Z TUESDAY WITH BRISK WINDS OF 15KT CONTINUING THROUGH 12Z TUESDAY. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE/LONG TERM...RP KINNEY SHORT TERM/AVIATION...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1217 AM CST MON DEC 16 2013 .UPDATE... ISSUED AT 1217 AM CST MON DEC 16 2013 LATEST WATER VAPOR SHOWS THE NEXT UPSTREAM SHORTWAVE NOW SEEN CIRCULATING INTO SOUTHWEST MANITOBA. REGIONAL RADAR HAS AN AREA OF LIGHT SNOW SHIFTING ACROSS THE NORTHERN BORDER WILL BE WATCHED CLOSELY AS THE PREVIOUS FORECAST CAPTURED THE POTENTIAL FOR FREEZING RAIN AS WARMER AIR CONTINUES TO ADVECT IN FROM THE WEST. THE HRRR AND RAP13 HAVE AN AREA OF LIGHT SNOW FOLLOWED BY A POCKET OF LIGHT FREEZING RAIN ON ITS BACKEDGE SPREADING FROM NORTHWEST TO SOUTHEAST OVERNIGHT. THIS IS ALSO CONFIRMED ON THE NAM HOURLY BUFKIT SOUNDINGS. THE CURRENT FORECAST HAS THIS HANDLED WELL WITH LITTLE CHANGES NEEDED AT THIS TIME. UPDATE ISSUED AT 949 PM CST SUN DEC 15 2013 MAIN UPDATE CONCERN WAS INCREASING WINDS LATE TONIGHT INTO MONDAY AND POSSIBLY SOME MIXED PRECIPITATION. 16 DEC 00 UTC NAM SOUNDINGS SHOW QUITE A BIT OF WARM AIR ALOFT LATEST HRRR CONTINUES TO INDICATE A BAND OF LIGHT PRECIPITATION MOVING NORTHWEST TO SOUTHEAST ACROSS THE AREA LATE TONIGHT. IF THIS DEVELOPS...NAM SOUNDINGS INDICATE A POSSIBILITY OF FREEZING RAIN OR SLEET. AS YOU GET INTO EASTERN PORTIONS OF CENTRAL NORTH DAKOTA IT MAY REMAIN COLD ENOUGH FOR ALL SNOW. PRECIPITATION SHOULD REMAIN LIGHT SO AT THIS TIME AM NOT ANTICIPATING ANY ADVISORY. WILL MENTION THE POSSIBILITY OF MIXED PRECIPITATION IN THE UPDATED HWO. WILL ALSO MENTION PATCHY BLOWING SNOW...MAINLY NORTH LATE TONIGHT INTO MONDAY AS WEST WINDS INCREASE BEHIND THE WARM FRONT. UPDATED PRODUCTS WILL BE SENT OUT SHORTLY. UPDATE ISSUED AT 658 PM CST SUN DEC 15 2013 WILL NEED TO CONTINUE AND MONITOR TEMPERATURES THROUGH THE EVENING. WARM FRONT REMAINS OVER WESTERN NORTH DAKOTA AND WILL LIKELY BE A FEW MORE HOURS BEFORE IT BEGINS TO MAKE PROGRESS EASTWARD. THUS WILL NEED TO MODIFY EVENING TEMPERATURES WITH CENTRAL AND EASTERN AREAS STARTING OUT WITH TEMPERATURES MAINLY IN THE SINGLE DIGITS ABOVE ZERO...WITH THE FAR EAST IN THE SINGLE DIGITS BELOW ZERO. TEMPERATURES ARE EXPECTED TO RISE OVERNIGHT SO THESE WILL LIKELY BE THE OVERNIGHT LOWS...UNLESS WE WOULD DROP A FEW MORE DEGREES BEFORE TEMPERATURES BEGIN TO CLIMB. LATEST RAP AND ESPECIALLY HRRR SEEM TO HAVE A REASONABLE HANDLE ON THE CURRENT LIGHT SNOW OVER THE NORTHEAST CWA. UTILIZED THE HRRR FOR SHORT TERM POPS TONIGHT. THE AREA OVER THE NORTH CENTRAL MOVES SOUTHEAST WITH ANOTHER AREA OF LIGHT SNOW DEVELOPING OVER THE NORTHWEST LATER THIS EVENING AND SPREADING SOUTHEAST AS THE WARM FRONT TRACKS EAST ACROSS THE CWA. && .SHORT TERM...(TODAY THROUGH MONDAY AFTERNOON) ISSUED AT 319 PM CST SUN DEC 15 2013 FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE CHANCES FOR LIGHT SNOW TONIGHT AND MONDAY...ALONG WITH A WARMING TREND OVER THE NEXT 24 HOURS FOR MOST LOCATIONS. CURRENTLY...LIGHT SNOW CONTINUES TO DIMINISH AND PUSH EAST AS FORCING AHEAD OF A SFC TROUGH DECREASES. SKIES HAVE PARTIALLY CLEARED WEST CENTRAL AND SOUTHWEST BEHIND THE TROUGH. LEFT EXIT REGION OF AN UPPER LEVEL JET STREAK WILL REMAIN ALOFT AT LEAST THROUGH TONIGHT. COUPLED WITH A WEAK MID LEVEL DISTURBANCE WILL MAINTAIN A SLIGHT CHANCE OF LIGHT SNOW MOST LOCATIONS THROUGH 12Z ALONG WITH CLOUDY SKIES. WEAK CAA TONIGHT INTO MONDAY...HOWEVER WITH THE INCREASE IN MIXING WE EXPECT THE ARCTIC AIR TO BE SCOURED OUT RESULTING IN STEADY TO WARMING TEMPERATURES TONIGHT INTO MONDAY. HIGHS IN THE 30S WILL BE COMMON ACROSS WEST AND CENTRAL NORTH DAKOTA MONDAY AFTERNOON. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 319 PM CST SUN DEC 15 2013 THE MAIN FORECAST ISSUE IS THE POTENTIAL FOR ANOTHER ROUND OF SNOW AND COLDER TEMPERATURES MID TO LATE WEEK. RELATIVELY MILD AIR WILL OVERSPREAD THE ENTIRE FORECAST AREA ON MONDAY AND WILL CONTINUE MONDAY NIGHT THROUGH TUESDAY NIGHT. A REINFORCEMENT OF MILD PACIFIC AIR WILL MOVE INTO THE REGION TUESDAY NIGHT AS AN ALBERTA CLIPPER LOW PRESSURE SYSTEM MOVES FROM ALBERTA TUESDAY AFTERNOON TO SOUTHERN MANITOBA BY WEDNESDAY MORNING...WITH A WARM FRONT EXTENDING FROM THE LOW THAT WILL MOVE EAST ACROSS NORTH DAKOTA TUESDAY NIGHT. ON WEDNESDAY AN ARCTIC COLD FRONT IS FORECAST TO ENTER NORTHERN NORTH DAKOTA LATE MORNING/NOON...AND MOVE SOUTH ACROSS THE STATE REACHING THE SOUTH DAKOTA BORDER BY/DURING WEDNESDAY EVENING. THUS A LARGE TEMPERATURE DIFFERENCE FROM NORTH TO SOUTH ACROSS THE STATE ON WEDNESDAY. TEMPERATURES SHOULD REACH INTO THE TEENS TO LOWER 20S ALONG AND AHEAD OF THE ARCTIC FRONT IN THE NORTHERN COUNTIES...AND REACH INTO THE UPPER 20S/MID 30S SOUTHERN COUNTIES. AS THE SURFACE ARCTIC FRONT MOVES SOUTH...AN UPPER LEVEL TROUGH WILL DIG SOUTHWARD ACROSS THE ROCKIES/FRONT RANGE...AND THE TROUGH AXIS AND ACCOMPANYING ENERGY IMPULSE WILL ACT TO INDUCE SNOWFALL ALONG AND BEHIND THE ARCTIC FRONT. AT THIS TIME THE MODEL SOLUTIONS APPEAR TO COME CLOSER TO AGREEMENT...WITH SNOWFALL IN MONTANA WEDNESDAY...EXPANDING EASTWARD INTO NORTH DAKOTA WEDNESDAY NIGHT AND THURSDAY...AND EXITING THE STATE TO THE EAST THURSDAY NIGHT. CURRENT MODELS SUGGEST SOUTHERN NORTH DAKOTA AND NORTHERN SOUTH DAKOTA WOULD BE THE TARGET FOR HIGHEST PRECIPITATION AMOUNTS. CURRENT ESTIMATES ARE THAT IN A TIME PERIOD OF WEDNESDAY NIGHT THROUGH THURSDAY NIGHT: 2 TO 3 INCHES OF SNOW ALONG AND SOUTH OF INTERSTATE 94...TO AROUND 1/2 INCH ALONG THE CANADIAN BORDER. THE ARCTIC AIR REMAINS IN PLACE THURSDAY THROUGH FRIDAY/FRIDAY NIGHT. LOW TEMPERATURES BELOW ZERO IN THE NORTH WEDNESDAY NIGHT...AND OVER ALL OF NORTH DAKOTA THURSDAY NIGHT...AND MOST AREAS FRIDAY NIGHT. WIND CHILL HEADLINES MAY BE NEEDED THURSDAY NIGHT THROUGH FRIDAY MORNING. THEN SOME MODERATION OVER THE WEEKEND - BUT STILL BELOW AVERAGE TEMPERATURES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1217 AM CST MON DEC 16 2013 THROUGH 14Z MONDAY...HAVE INCLUDED A BRIEF PERIOD OF LIGHT SNOW AND FREEZING RAIN FROM KMOT TO KJMS. USED A VCSH FROM KISN/KBIS/KDIK. AFTER 14Z MONDAY...BRISK WEST TO NORTHWEST WINDS OF 15 TO 30 MPH WILL TAKE CONTROL ACROSS WESTERN AND CENTRAL NORTH DAKOTA. EXPECT MAINLY VFR CIGS AND VSBYS THROUGH THE PERIOD. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KS SHORT TERM...NH LONG TERM...JV AVIATION...KS
AREA FORECAST DISCUSSION...UPDATED
NWS PORTLAND OR
532 AM PST MON DEC 16 2013 .SYNOPSIS...AREAS OF FOG ACROSS THE REGION THIS MORNING. HIGH PRESSURE WILL BUILD TODAY FOR INCREASING OFFSHORE FLOW...AND POSSIBLE CLEARING TONIGHT. CLEAR SKIES COMBINED WITH LIGHT WINDS WILL RESULT IN COOLER TEMPERATURES LATE TONIGHT WITH MORE VALLEY FOG AND POSSIBLY FREEZING FOG FOR TUESDAY MORNING. A COLDER SYSTEM WILL BRING RAIN AND MOUNTAIN SNOW TUESDAY NIGHT AND WEDNESDAY. THERE WILL BE A BREAK IN PRECIPITATION THURSDAY BEFORE A SERIES OF WARMER SYSTEMS BRING PERIODS OF RAIN AND MOUNTAIN SNOW FRIDAY AND THROUGH THE WEEKEND. && .UPDATE...FOG HAS LIFTED IN MANY AREAS WARRANTING THE CANCELLATION OF THE DENSE FOG ADVISORY. THERE WILL BE PATCHY DENSE FOG THROUGH THE MORNING. PREVIOUS SHORT TERM DISCUSSION...TODAY THROUGH WEDNESDAY NIGHT...THE WEAK FRONT AND LOW-LEVEL PRECIPITATION THAT STALLED OVER THE AREA LAST NIGHT IS DISSIPATING AND PUSHING EASTWARD EARLY THIS MORNING. SURFACE WINDS ARE EASING OVER THE AREA AND WIDESPREAD FOG HAS DEVELOPED. VISIBILITIES ARE MOSTLY AROUND A HALF OF A MILE...BUT SHOULD LOWER TO A QUARTER OF A MILE IN THE NEXT COUPLE OF HOURS AS THE WINDS CONTINUE TO EASE. THIS FOG WILL LIKELY CONTINUE THROUGH THE MORNING COMMUTE AND HAVE CONTINUED THE DENSE FOG ADVISORY FOR THE WILLAMETTE VALLEY AND ALONG THE I-5 CORRIDOR OF THE LOWER COLUMBIA RIVER. ALTHOUGH NOT CURRENTLY INCLUDED IN THE ADVISORY...THE COAST WILL ALSO HAVE POCKETS OF DENSE FOG. WILL MONITOR WEB CAMERAS FOR THE COASTAL FOG AND UPDATE THE FORECAST IF THE DENSE FOG BECOMES MORE WIDESPREAD. HIGH PRESSURE ALOFT WILL STRENGTHEN OVER THE AREA TODAY AND HOLD THROUGH TUESDAY WITH A STRONG SUBSIDENCE INVERSION OVER THE AREA RESULTING IN WARMER TEMPERATURES FOR THE HIGHER TERRAIN THAN THE LOWER ELEVATIONS. THE INVERSION WILL ALSO LIMIT MIXING TO THE LOWER LEVELS AND VALLEY FOG MAY REMAIN INTO THE AFTERNOON. THE HRRR MODEL FORECASTS FOG WITH VISIBILITIES AT OR BELOW A HALF OF A MILE IN THE INTERIOR VALLEYS THROUGH 21Z (1 PM). A THERMAL TROUGH WILL DEVELOP OVER THE COAST TODAY AND WEAK N-NE WINDS SHOULD AID IN THE FOG CLEARING SOMEWHAT THIS AFTERNOON. HOWEVER...THE NORTHERLY FLOW WILL PROBABLY CAUSE LEFTOVER LOW CLOUDS TO BANK UP AGAINST THE SOUTH END OF THE WILLAMETTE VALLEY...LEADING TO A COOL AND CLOUDY CONDITIONS FOR THE SOUTH VALLEY. CLEARING IS LIKELY THIS EVENING IN MOST AREAS EXCEPT FOR THE SOUTHERN WILLAMETTE VALLEY AS PREVIOUSLY DISCUSSED. ANY CLEARING WILL LEAD TO ENHANCED RADIATION COOLING WITH NEAR FREEZING TEMPERATURES EARLY TUESDAY MORNING. FOG WILL AGAIN DEVELOP IN THE INTERIOR VALLEYS AS THE WINDS EASE LATE TONIGHT WITH THE POSSIBILITY FOR AT LEAST SPOTTY FREEZING FOG TUESDAY MORNING. WITH LIGHT FLOW AND INCREASING HIGH CLOUDS TUESDAY AHEAD OF AN APPROACHING FRONT ANY LOW CLOUDS WILL BE STUBBORN AND SLOW TO DISSIPATE UNDER THE STRONGER INVERSION. WHILE VALLEYS REMAIN IN THE UPPER 30S AND 40S...FOOTHILLS MAY WARM TO THE MID TO UPPER 50S. A WEAK COLD FRONT WILL BRING INCREASING CHANCES FOR PRECIPITATION ACROSS THE NORTH TUESDAY EVENING AND NIGHT. THE FRONT WILL SLOWLY MOVE SOUTHWARD WITH PRECIPITATION REACHING SOUTHERN AREAS BY WEDNESDAY AFTERNOON. MODEL SOUNDINGS SHOW THAT THE MOISTURE WILL AGAIN BE CONFINED TO THE LOWER LEVELS WITH THIS FRONT AND THINK THE PRECIPITATION WILL BE REALLY LIGHT WITH A MIX OF DRIZZLE AND RAIN. SNOW LEVELS WILL INITIALLY BE HIGH...ABOVE 6000 FEET. COLDER AIR BEHIND THE FRONT WILL LOWER SNOW LEVELS DOWN TO AROUND 1500 TO 2000 FEET WEDNESDAY NIGHT. MODELS ARE FORECASTING THAT A SHORTWAVE TROUGH WILL ENHANCE PRECIPITATION OVER THE CASCADES LATE WEDNESDAY NIGHT...AND EXPECT A QUICK BURST OF ACCUMULATING SNOW FOR THE CASCADES AND CASCADE FOOTHILLS. HARTLEY .LONG TERM...THURSDAY THROUGH SUNDAY...MOUNTAIN SHOWERS WILL DECREASE THURSDAY MORNING AS THE UPPER RIDGE REASSERTS ITSELF OVER THE PACIFIC NW...WITH WIDESPREAD FOG ALONG THE COAST AND THE INTERIOR VALLEYS. THURSDAY WILL BE DRY BUT CLOUDY. MODELS ARE IN BETTER AGREEMENT THAT THE NEXT FRONT WILL APPROACH FROM THE NORTH THURSDAY NIGHT AND DRAG PRECIPITATION FROM NORTH TO SOUTH ACROSS THE AREA FRIDAY AND SATURDAY. ONSHORE WINDS SHOULD RAPIDLY RAISE SNOW LEVELS BEFORE THE ONSET OF PRECIPITATION AND EXPECT SNOW TO BE LIMITED TO THE CASCADES. SNOW LEVELS SHOULD RISE ABOVE PASS LEVEL FRIDAY NIGHT. MODELS HINT OF A DIRTY RIDGE PATTERN THROUGH EARLY NEXT WEEK WITH A SERIES OF WEAK SYSTEMS RIDING OVER THE RIDGE AND BRINGING PERIODS OF LIGHT RAIN AND MOUNTAIN SNOW. HARTLEY && .AVIATION...WIDESPREAD LIFR AND IFR CONDITIONS EXIST ACROSS THE AREA EARLY THIS MORNING. WITH INCREASING...ALBEIT LIGHT...OFFSHORE FLOW...KONP SHOULD IMPROVE TO VFR THIS MORNING. HOWEVER...IMPROVEMENT WILL BE SLOWER TO OCCUR FOR THE REST OF THE TAF SITES. THERE IS A DISTINCT POSSIBILITY THAT SEVERAL OF THE INLAND TAF SITES...ESPECIALLY KSLE AND KEUG...MAY STAY IFR THROUGH THE FORECAST PERIOD. HOWEVER...FOR NOW WE WILL CONTINUE THE TREND THAT AT LEAST SOME MVFR TO EVEN VFR CONDITIONS WILL DEVELOP FOR THE PORTLAND TAF SITES DURING THE AFTERNOON AS WEAK EASTERLY AND NORTHERLY FLOW HELPS MIX OUT SOME OF THE LOW LEVEL MOISTURE. WHAT IMPROVEMENT DOES OCCUR MONDAY AFTERNOON...WILL LIKELY DETERIORATE QUICKLY TO IFR AND LIFR CONDITIONS TOWARDS 03Z TUESDAY FOR MOST TAF SITES AWAY FROM THE COLUMBIA RIVER. KPDX AND APPROACHES...IFR TO LIFR CONDITIONS SHOULD PERSIST UNTIL APPROXIMATELY 20Z MONDAY. LIGHT EASTERLY FLOW SHOULD ALLOW CONDITIONS TO IMPROVE TO VFR FOR SEVERAL HOURS THIS AFTERNOON. VFR CONDITIONS WILL LIKELY DETERIORATE TO LIFR/IFR CONDITIONS TOWARDS 03-06Z TUESDAY. /NEUMAN && .MARINE...WINDS REMAIN RATHER LIGHT ACROSS THE WATERS EARLY THIS MORNING WITH THIS TREND CONTINUING THROUGH TUESDAY NIGHT. HOWEVER...SEAS ARE CURRENTLY IN THE 12-13 FT RANGE. LATEST MODEL GUIDANCE SUGGESTS THESE WILL DROP BELOW 10 FT TOWARDS MIDDAY. HOWEVER...WILL KEEP THE SMALL CRAFT FOR SEAS OUT THROUGH 00Z TO ACCOUNT FOR SOME OF THE UNCERTAINTY. OTHERWISE...A WEAK FRONT WILL PUSH INTO THE WATERS TUESDAY NIGHT. MODELS CONTINUE TO SUGGEST POST FRONTAL NORTHWESTERLIES WILL REACH SMALL CRAFT THRESHOLDS OF 25 TO 30 KT LATE WEDNESDAY. THIS SHOULD PUSH SEAS BACK UP TOWARDS 10 FT THURSDAY. ANOTHER SYSTEM LOOKS ON TAP FOR FRIDAY...BUT AT THIS POINT...GALE FORCE OR HIGHER WINDS ARE NOT ANTICIPATED. /NEUMAN && .PQR WATCHES/WARNINGS/ADVISORIES... OR...DENSE FOG ADVISORY UNTIL 10 AM PST THIS MORNING FOR CENTRAL WILLAMETTE VALLEY-GREATER PORTLAND METRO AREA-LOWER COLUMBIA-SOUTH WILLAMETTE VALLEY. WA...DENSE FOG ADVISORY UNTIL 10 AM PST THIS MORNING FOR GREATER VANCOUVER AREA. PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM PST THIS AFTERNOON FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM. SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST THIS AFTERNOON. && $$ MORE WEATHER INFORMATION ONLINE AT.. HTTP://WEATHER.GOV/PORTLAND INTERACT WITH US VIA SOCIAL MEDIA WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV WWW.TWITTER.COM/NWSPORTLAND THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS PORTLAND OR
301 AM PST MON DEC 16 2013 .SYNOPSIS...AREAS OF FOG ACROSS THE REGION THIS MORNING WITH PATCHY DENSE FOG LIKELY DURING THE MORNING COMMUTE. HIGH PRESSURE WILL BUILD TODAY FOR INCREASING OFFSHORE FLOW...AND POSSIBLE CLEARING TONIGHT. CLEAR SKIES COMBINED WITH LIGHT WINDS WILL RESULT IN COOLER TEMPERATURES LATE TONIGHT WITH MORE VALLEY FOG AND POSSIBLY FREEZING FOG FOR TUESDAY MORNING. A COLDER SYSTEM WILL BRING RAIN AND MOUNTAIN SNOW TUESDAY NIGHT AND WEDNESDAY. THERE WILL BE A BREAK IN PRECIPITATION THURSDAY BEFORE A SERIES OF WARMER SYSTEMS BRING PERIODS OF RAIN AND MOUNTAIN SNOW FRIDAY AND THROUGH THE WEEKEND. && .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...THE WEAK FRONT AND LOW-LEVEL PRECIPITATION THAT STALLED OVER THE AREA LAST NIGHT IS DISSIPATING AND PUSHING EASTWARD EARLY THIS MORNING. SURFACE WINDS ARE EASING OVER THE AREA AND WIDESPREAD FOG HAS DEVELOPED. VISIBILITIES ARE MOSTLY AROUND A HALF OF A MILE...BUT SHOULD LOWER TO A QUARTER OF A MILE IN THE NEXT COUPLE OF HOURS AS THE WINDS CONTINUE TO EASE. THIS FOG WILL LIKELY CONTINUE THROUGH THE MORNING COMMUTE AND HAVE CONTINUED THE DENSE FOG ADVISORY FOR THE WILLAMETTE VALLEY AND ALONG THE I-5 CORRIDOR OF THE LOWER COLUMBIA RIVER. ALTHOUGH NOT CURRENTLY INCLUDED IN THE ADVISORY...THE COAST WILL ALSO HAVE POCKETS OF DENSE FOG. WILL MONITOR WEB CAMERAS FOR THE COASTAL FOG AND UPDATE THE FORECAST IF THE DENSE FOG BECOMES MORE WIDESPREAD. HIGH PRESSURE ALOFT WILL STRENGTHEN OVER THE AREA TODAY AND HOLD THROUGH TUESDAY WITH A STRONG SUBSIDENCE INVERSION OVER THE AREA RESULTING IN WARMER TEMPERATURES FOR THE HIGHER TERRAIN THAN THE LOWER ELEVATIONS. THE INVERSION WILL ALSO LIMIT MIXING TO THE LOWER LEVELS AND VALLEY FOG MAY REMAIN INTO THE AFTERNOON. THE HRRR MODEL FORECASTS FOG WITH VISIBILITIES AT OR BELOW A HALF OF A MILE IN THE INTERIOR VALLEYS THROUGH 21Z (1 PM). A THERMAL TROUGH WILL DEVELOP OVER THE COAST TODAY AND WEAK N-NE WINDS SHOULD AID IN THE FOG CLEARING SOMEWHAT THIS AFTERNOON. HOWEVER...THE NORTHERLY FLOW WILL PROBABLY CAUSE LEFTOVER LOW CLOUDS TO BANK UP AGAINST THE SOUTH END OF THE WILLAMETTE VALLEY...LEADING TO A COOL AND CLOUDY CONDITIONS FOR THE SOUTH VALLEY. CLEARING IS LIKELY THIS EVENING IN MOST AREAS EXCEPT FOR THE SOUTHERN WILLAMETTE VALLEY AS PREVIOUSLY DISCUSSED. ANY CLEARING WILL LEAD TO ENHANCED RADIATION COOLING WITH NEAR FREEZING TEMPERATURES EARLY TUESDAY MORNING. FOG WILL AGAIN DEVELOP IN THE INTERIOR VALLEYS AS THE WINDS EASE LATE TONIGHT WITH THE POSSIBILITY FOR AT LEAST SPOTTY FREEZING FOG TUESDAY MORNING. WITH LIGHT FLOW AND INCREASING HIGH CLOUDS TUESDAY AHEAD OF AN APPROACHING FRONT ANY LOW CLOUDS WILL BE STUBBORN AND SLOW TO DISSIPATE UNDER THE STRONGER INVERSION. WHILE VALLEYS REMAIN IN THE UPPER 30S AND 40S...FOOTHILLS MAY WARM TO THE MID TO UPPER 50S. A WEAK COLD FRONT WILL BRING INCREASING CHANCES FOR PRECIPITATION ACROSS THE NORTH TUESDAY EVENING AND NIGHT. THE FRONT WILL SLOWLY MOVE SOUTHWARD WITH PRECIPITATION REACHING SOUTHERN AREAS BY WEDNESDAY AFTERNOON. MODEL SOUNDINGS SHOW THAT THE MOISTURE WILL AGAIN BE CONFINED TO THE LOWER LEVELS WITH THIS FRONT AND THINK THE PRECIPITATION WILL BE REALLY LIGHT WITH A MIX OF DRIZZLE AND RAIN. SNOW LEVELS WILL INITIALLY BE HIGH...ABOVE 6000 FEET. COLDER AIR BEHIND THE FRONT WILL LOWER SNOW LEVELS DOWN TO AROUND 1500 TO 2000 FEET WEDNESDAY NIGHT. MODELS ARE FORECASTING THAT A SHORTWAVE TROUGH WILL ENHANCE PRECIPITATION OVER THE CASCADES LATE WEDNESDAY NIGHT...AND EXPECT A QUICK BURST OF ACCUMULATING SNOW FOR THE CASCADES AND CASCADE FOOTHILLS. HARTLEY .LONG TERM...THURSDAY THROUGH SUNDAY...MOUNTAIN SHOWERS WILL DECREASE THURSDAY MORNING AS THE UPPER RIDGE REASSERTS ITSELF OVER THE PACIFIC NW...WITH WIDESPREAD FOG ALONG THE COAST AND THE INTERIOR VALLEYS. THURSDAY WILL BE DRY BUT CLOUDY. MODELS ARE IN BETTER AGREEMENT THAT THE NEXT FRONT WILL APPROACH FROM THE NORTH THURSDAY NIGHT AND DRAG PRECIPITATION FROM NORTH TO SOUTH ACROSS THE AREA FRIDAY AND SATURDAY. ONSHORE WINDS SHOULD RAPIDLY RAISE SNOW LEVELS BEFORE THE ONSET OF PRECIPITATION AND EXPECT SNOW TO BE LIMITED TO THE CASCADES. SNOW LEVELS SHOULD RISE ABOVE PASS LEVEL FRIDAY NIGHT. MODELS HINT OF A DIRTY RIDGE PATTERN THROUGH EARLY NEXT WEEK WITH A SERIES OF WEAK SYSTEMS RIDING OVER THE RIDGE AND BRINGING PERIODS OF LIGHT RAIN AND MOUNTAIN SNOW. HARTLEY && .AVIATION...WIDESPREAD LIFR AND IFR CONDITIONS EXIST ACROSS THE AREA EARLY THIS MORNING. WITH INCREASING...ALBEIT LIGHT...OFFSHORE FLOW...KONP SHOULD IMPROVE TO VFR THIS MORNING. HOWEVER...IMPROVEMENT WILL BE SLOWER TO OCCUR FOR THE REST OF THE TAF SITES. THERE IS A DISTINCT POSSIBILITY THAT SEVERAL OF THE INLAND TAF SITES...ESPECIALLY KSLE AND KEUG...MAY STAY IFR THROUGH THE FORECAST PERIOD. HOWEVER...FOR NOW WE WILL CONTINUE THE TREND THAT AT LEAST SOME MVFR TO EVEN VFR CONDITIONS WILL DEVELOP FOR THE PORTLAND TAF SITES DURING THE AFTERNOON AS WEAK EASTERLY AND NORTHERLY FLOW HELPS MIX OUT SOME OF THE LOW LEVEL MOISTURE. WHAT IMPROVEMENT DOES OCCUR MONDAY AFTERNOON...WILL LIKELY DETERIORATE QUICKLY TO IFR AND LIFR CONDITIONS TOWARDS 03Z TUESDAY FOR MOST TAF SITES AWAY FROM THE COLUMBIA RIVER. KPDX AND APPROACHES...IFR TO LIFR CONDITIONS SHOULD PERSIST UNTIL APPROXIMATELY 20Z MONDAY. LIGHT EASTERLY FLOW SHOULD ALLOW CONDITIONS TO IMPROVE TO VFR FOR SEVERAL HOURS THIS AFTERNOON. VFR CONDITIONS WILL LIKELY DETERIORATE TO LIFR/IFR CONDITIONS TOWARDS 03-06Z TUESDAY. /NEUMAN && .MARINE...WINDS REMAIN RATHER LIGHT ACROSS THE WATERS EARLY THIS MORNING WITH THIS TREND CONTINUING THROUGH TUESDAY NIGHT. HOWEVER...SEAS ARE CURRENTLY IN THE 12-13 FT RANGE. LATEST MODEL GUIDANCE SUGGESTS THESE WILL DROP BELOW 10 FT TOWARDS MIDDAY. HOWEVER...WILL KEEP THE SMALL CRAFT FOR SEAS OUT THROUGH 00Z TO ACCOUNT FOR SOME OF THE UNCERTAINTY. OTHERWISE...A WEAK FRONT WILL PUSH INTO THE WATERS TUESDAY NIGHT. MODELS CONTINUE TO SUGGEST POST FRONTAL NORTHWESTERLIES WILL REACH SMALL CRAFT THRESHOLDS OF 25 TO 30 KT LATE WEDNESDAY. THIS SHOULD PUSH SEAS BACK UP TOWARDS 10 FT THURSDAY. ANOTHER SYSTEM LOOKS ON TAP FOR FRIDAY...BUT AT THIS POINT...GALE FORCE OR HIGHER WINDS ARE NOT ANTICIPATED. /NEUMAN && .PQR WATCHES/WARNINGS/ADVISORIES... OR...DENSE FOG ADVISORY UNTIL 10 AM PST THIS MORNING FOR CENTRAL WILLAMETTE VALLEY-GREATER PORTLAND METRO AREA-LOWER COLUMBIA-SOUTH WILLAMETTE VALLEY. WA...DENSE FOG ADVISORY UNTIL 10 AM PST THIS MORNING FOR GREATER VANCOUVER AREA. PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM PST THIS AFTERNOON FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM. SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST THIS AFTERNOON. && $$ MORE WEATHER INFORMATION ONLINE AT.. HTTP://WEATHER.GOV/PORTLAND INTERACT WITH US VIA SOCIAL MEDIA WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV WWW.TWITTER.COM/NWSPORTLAND THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS PORTLAND OR
925 PM PST SUN DEC 15 2013 .SYNOPSIS...A WEAK STATIONARY FRONT IS DISSIPATING OVER OREGON THIS EVENING LEAVING PLENTY OF LOW LEVEL MOISTURE BEHIND. THIS MOISTURE WILL RESULT IN LOCALLY DENSE FOG TONIGHT AND MONDAY MORNING. HIGH PRESSURE WILL BUILD INTO THE PACIFIC NORTHWEST MONDAY FOR INCREASING OFFSHORE FLOW...WHICH SHOULD CONFINE THE FOG MORE TOWARD EUGENE LATER MONDAY INTO TUESDAY. A COLDER SYSTEM IS EXPECTED TO BRING RAIN AND MOUNTAIN SNOW BY WEDNESDAY...WITH SNOW LEVELS LOWERING WELL INTO THE FOOTHILLS BY THURSDAY. LOW SNOW LEVELS WILL PERSIST THURSDAY NIGHT INTO EARLY FRIDAY AS THE NEXT PACIFIC FRONT APPROACHES...BUT WARMER AIR IS EXPECTED TO PUSH IN WITH THE FRONT LATER FRIDAY AND SATURDAY. && .UPDATE...BAROCLINIC ZONE WILL REMAIN DRAPED OVER THE AREA TONIGHT. ANY MINIMAL FORCING ON THE FRONT WILL TAPER OFF TONIGHT...BUT EXPECT A FEW MORE HOURS OF DRIZZLE AT THE COAST/COAST RANGE...AND IN THE HIGHER TERRAIN. WINDS ARE EASING UP AND WE ARE STARTING TO SEE SOME MORE FOG AND LOWERING OF THE CLOUD DECK...BUT FEEL THAT IT WILL BE A LATER START TO MORE WIDESPREAD DENSE FOG...AND THIS IS CONFIRMED BY THE HRRR SFC VISBY PROG SHOWING A LOWERING OF CIGS/REDUCED VISBYS LATE TONIGHT INTO EARLY MONDAY. ISSUED A DENSE FOG ADVISORY FOR MUCH OF THE VALLEY...THAT WILL AFFECT SOME AREAS FOR THE MONDAY MORNING COMMUTE. WILL WATCH WEB CAMS CLOSELY TO SEE IF DENSE FOG BECOMES MORE WIDESPREAD ALONG THE COAST. HAD SPOTTER REPORTS OF LOWERING VSBYS NEAR TILLAMOOK AND ALREADY HAVE PRETTY THICK FOG AROUND ASTORIA. /KMD .SHORT TERM...TONIGHT THROUGH WEDNESDAY...A WEAK COLD FRONT STALLED OVER OREGON EARLIER TODAY...AND IS NOW DISSIPATING AS A STATIONARY FRONT ACROSS THE REGION. THE BULK OF THE PRECIPITATION MOVED THROUGH WITH A FAST-MOVING SHORTWAVE EARLIER TODAY...BUT THERE ARE STILL SOME AREAS OF LIGHT RAIN AND DRIZZLE WITHIN THE LEFTOVER LOW-LEVEL MOIST LAYER. EXPECT THESE AREAS TO BECOME MORE CONFINED TO THE HIGHER TERRAIN OVERNIGHT AS HIGH PRESSURE BUILDS IN FROM THE PACIFIC. WITH RIDGING DEVELOPING AT THE SURFACE AND ALOFT...CONDITIONS WILL BE IDEAL FOR INVERSION BUILDING TONIGHT. WITH ABUNDANT MOISTURE TRAPPED WITHIN THE INVERSION EXPECT FOG TO BE FAIRLY WIDESPREAD TONIGHT...BECOMING DENSE IN THE WILLAMETTE VALLEY. A THERMAL TROUGH EXTENDING NORTHWARD FROM THE CALIFORNIA COAST SHOULD INDUCE SOME NORTHERLY FLOW MONDAY...ALLOWING FOR SOME MIXING MOST AREAS. HOWEVER THE NORTHERLY FLOW WILL PROBABLY CAUSE LEFTOVER LOW CLOUDS TO BANK UP AGAINST THE SOUTH END OF THE WILLAMETTE VALLEY...LEADING TO A COOL AND CLAMMY DAY WITH HIGHS AROUND 40 MONDAY AS MOST OTHER AREAS AIM FOR 50 DEGREES...OR AT LEAST THE UPPER 40S IF CLOUDS ARE A BIT PESKIER AS SOME GUIDANCE SUGGESTS. SHOULD BE A NICE DAY IN THE FOOTHILLS AND CASCADES. NORTHERLY FLOW WILL WANE MONDAY NIGHT AND TUESDAY...POSSIBLY ALLOWING SOME FOG TO FORM IN THE VALLEYS AWAY FROM THE WEST END OF THE COLUMBIA GORGE. WITH 12Z MET/MAV GUIDANCE SHOWING LOWER DEWPOINTS OUTLYING VALLEYS...WILL HAVE A BETTER SHOT AT GETTING BELOW FREEZING AND THUS AREAS OF FREEZING FOG TUE MORNING. WITH LIGHT FLOW AND INCREASING HIGH CLOUDS TUESDAY ANY LOW CLOUDS SHOULD BE FAIRLY PERSISTENT AND SLOW TO BURN OFF IN THE STRONGER INVERSION. WHILE VALLEYS REMAIN IN THE UPPER 30S AND 40S...18Z NAM 850 MB TEMPS AROUND +5 TO +6 DEG C SHOULD SUPPORT TEMPS IN THE MID TO UPPER 50S IN THE FOOTHILLS ABOVE THE INVERSION. COASTAL AREAS SHOULD ALSO BE FAIRLY MILD BOTH MONDAY AND TUESDAY. MEANWHILE A SYSTEM PRESENTLY OUT IN THE PACIFIC NEAR 160W SHOULD MERGE WITH A COLD GULF OF ALASKA LOW OVER THE NEXT 24-48 HOURS... EVENTUALLY PUSHING A COLD FRONT FROM THE GULF OF ALASKA SOUTH TOWARD THE PACIFIC NORTHWEST LATE TUESDAY. AT THIS POINT MODEL CONSENSUS SHOWS FAIRLY LIGHT QPF...BUT THERE IS SOME POTENTIAL FOR A WEAK AND BRIEF SUBTROPICAL TAP TO SET UP WITH THIS FRONT. EITHER WAY...RAIN SHOULD SPREAD FROM NORTH TO SOUTH ACROSS THE FORECAST AREA TUE NIGHT AND WED...FOLLOWED BY COLDER AIR WITH SNOW LEVELS FALLING INTO THE COAST RANGE AND FOOTHILL ELEVATIONS BY WED NIGHT. WEAGLE .LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY. THE COLD FRONT WILL CONTINUE TO MOVE THROUGH THE AREA BY LATE WEDNESDAY NIGHT AND PRECIPITATION WILL TAPER OFF LEAVING ONLY A FEW LINGERING SHOWERS BY EARLY THURSDAY MORNING. THIS WILL BE IN THE FORM OF RAIN FOR THE LOWER ELEVATIONS AND SNOW IN THE CASCADES AS THE SNOW LEVELS WILL FALL BEHIND THE FRONT. THERE IS A CHANCE FOR SOME SNOW IN THE HIGHER ELEVATIONS OF THE COAST RANGE...BUT THIS IS DEPENDENT UPON HOW FAST SNOW LEVELS DROP BEFORE THE PRECIP ENDS. THURSDAY WILL BE DRY UNDER NORTHERLY FLOW ALOFT AHEAD OF THE NEXT SYSTEM. TIMING DIFFERENCES REMAIN BETWEEN FORECAST MODELS WITH THE ARRIVAL OF THIS SYSTEM...WITH THE 12Z ECMWF STILL ABOUT 12 HRS FASTER THAN THE GFS. IF THE SYSTEM DOES ARRIVE EARLIER...PRECIP MAY BEGIN AS SNOW FOR AREAS SUCH AS THE COAST RANGE...WILLAPA HILLS... AND CASCADE FOOTHILLS THROUGH EARLY FRIDAY MORNING. HOWEVER...THIS WILL LIKELY BE RAIN FOR MOST OF THE AREA AS SNOW LEVELS QUICKLY RISE...AND SNOW LEVELS SHOULD RISE ABOVE THE CASCADE PASSES BY SATURDAY MORNING. THIS RAIN WILL CONTINUE INTO SATURDAY AND ENHANCED BY A PASSING SHORTWAVE EMBEDDED IN THE UPPER LEVEL FLOW. ANOTHER DISTURBANCE MAY IMPACT THE NORTHERN PARTS OF THE AREA BY SUNDAY... BUT THIS FEATURE IS MUCH WEAKER IN THE 12Z ECMWF. CULLEN && .AVIATION...GENERALLY IFR ALONG THE COAST AND IN THE INTERIOR VALLEYS AS OF 04Z. HOWEVER...NOT NEARLY AS MUCH LIFR COMPARED TO 24 HOURS AGO. LIFR COVERAGE TO INCREASE THROUGH THE NIGHT WITH ABUNDANT LOW LEVEL MOISTURE IN PLACE AND LITTLE IN THE WAY OF WIND. MODELS SHOW A HINT OF N TO NE LOW-LEVEL FLOW DEVELOPING MON AFTERNOON...WITH THE NAM THE MOST PRONOUNCED WITH IT. WOULD EXPECT COASTAL SITES TO BECOME VFR BY AT LEAST 18Z MON...ESPECIALLY KONP. INLAND VALLEYS SHOULD ALSO ACHIEVE VFR CONDITIONS...BUT PROBABLY NOT UNTIL 20Z OR A BIT LATER. THE LOW-LEVEL NLY FLOW MAY KEEP KEUG IN MVFR OR WORSE THE ENTIRE DAY. KPDX AND APPROACHES...IFR TO LIFR CONDITIONS EXPECTED TO PERSIST THROUGH AT LEAST 20Z MON. A BETTER CHANCE OF IMPROVING TO VFR MON AFTERNOON WITH LIGHT LOW-LEVEL NE-E FLOW. WEISHAAR && .MARINE...SEAS AT 00Z WERE RUNNING ABOUT 1-2 FT BELOW ENP GUIDANCE VALID AT 00Z. SHORTLY BEFORE 04Z SEAS HAD RISEN TO 12-14 FT...CLOSE TO THE 06Z ENP FORECAST. THIS LONG-PERIOD SWELL TRAIN WILL CONTINUE THROUGH MON AFTERNOON. SEAS MAY DROP BELOW 10 FT A BIT EARLIER THAN GUIDANCE SUGGESTS...BUT WILL LEAVE THE SMALL CRAFT ADVISORY TIMING AS IS. LITTLE IN THE WAY OF WIND ISSUES FOR THE NEXT COUPLE OF DAYS. MODELS...ESPECIALLY THE NAM...DEVELOP A THERMAL TROUGH ALONG THE SOUTH OREGON COAST LATE TONIGHT THROUGH MON...WHICH COULD PRODUCE SOME N-NE 20 KT GUSTS OVER THE FAR SRN WATERS. BELIEVE THE NAM MAY BE A BIT OVERDONE WITH THIS THERMAL TROUGH FEATURE. ECMWF AND GFS NOT NEARLY AS STRONG WITH IT. ANOTHER WEAK FRONT IS EXPECTED TO PUSH THROUGH THE WATERS LATE TUE. THE MODELS INDICATE LOW END SMALL CRAFT ADVISORY WINDS MAY BE A POSSIBILITY IN THE NW POST FRONTAL WINDS ON WED. IN ADDITION SEAS MAY BUILD BACK NEAR 10 FT WED AND WED NIGHT. WEISHAAR && .PQR WATCHES/WARNINGS/ADVISORIES... OR...DENSE FOG ADVISORY FOR THE WILLAMETTE VALLEY...GREATER PORTLAND AREA AND LOWER COLUMBIA LATE TONIGHT THROUGH 10 AM MONDAY. WA...DENSE FOG ADVISORY FOR THE GREATER VANCOUVER AREA AND LOWER COLUMBIA LATE TONIGHT THROUGH 10 AM MONDAY. PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM PST MONDAY FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM. SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST MONDAY. && $$ MORE WEATHER INFORMATION ONLINE AT.. HTTP://WEATHER.GOV/PORTLAND INTERACT WITH US VIA SOCIAL MEDIA WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV WWW.TWITTER.COM/NWSPORTLAND THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS PORTLAND OR
900 PM PST SUN DEC 15 2013 .SYNOPSIS...A WEAK STATIONARY FRONT IS DISSIPATING OVER OREGON THIS EVENING LEAVING PLENTY OF LOW LEVEL MOISTURE BEHIND. THIS MOISTURE WILL RESULT IN LOCALLY DENSE FOG TONIGHT AND MONDAY MORNING. HIGH PRESSURE WILL BUILD INTO THE PACIFIC NORTHWEST MONDAY FOR INCREASING OFFSHORE FLOW...WHICH SHOULD CONFINE THE FOG MORE TOWARD EUGENE LATER MONDAY INTO TUESDAY. A COLDER SYSTEM IS EXPECTED TO BRING RAIN AND MOUNTAIN SNOW BY WEDNESDAY...WITH SNOW LEVELS LOWERING WELL INTO THE FOOTHILLS BY THURSDAY. LOW SNOW LEVELS WILL PERSIST THURSDAY NIGHT INTO EARLY FRIDAY AS THE NEXT PACIFIC FRONT APPROACHES...BUT WARMER AIR IS EXPECTED TO PUSH IN WITH THE FRONT LATER FRIDAY AND SATURDAY. && .UPDATE...BAROCLINIC ZONE WILL REMAIN DRAPED OVER THE AREA TONIGHT. ANY MINIMAL FORCING ON THE FRONT WILL TAPER OFF TONIGHT...BUT EXPECT A FEW MORE HOURS OF DRIZZLE AT THE COAST/COAST RANGE...AND IN THE HIGHER TERRAIN. WINDS ARE EASING UP AND WE ARE STARTING TO SEE SOME MORE FOG...BUT FEEL THAT IT WILL BE A LATER START TO MORE WIDESPREAD DENSE FOG...AND THIS IS CONFIRMED BY THE HRRR SFC VISBY PROG SHOWING A LOWERING OF CIGS/REDUCED VISBYS LATE TONIGHT INTO EARLY MONDAY. WE HAVE A POTENTIAL FOR A DENSE FOG ADVISORY TO BE ISSUED OVERNIGHT...JUST WORKING ON TIMING AS THIS WILL LIKELY AFFECT AREAS FOR THE MONDAY MORNING COMMUTE. MAY SEE THIS COME OUT AS EARLY AS THIS EVENING. /KMD .SHORT TERM...TONIGHT THROUGH WEDNESDAY...A WEAK COLD FRONT STALLED OVER OREGON EARLIER TODAY...AND IS NOW DISSIPATING AS A STATIONARY FRONT ACROSS THE REGION. THE BULK OF THE PRECIPITATION MOVED THROUGH WITH A FAST-MOVING SHORTWAVE EARLIER TODAY...BUT THERE ARE STILL SOME AREAS OF LIGHT RAIN AND DRIZZLE WITHIN THE LEFTOVER LOW-LEVEL MOIST LAYER. EXPECT THESE AREAS TO BECOME MORE CONFINED TO THE HIGHER TERRAIN OVERNIGHT AS HIGH PRESSURE BUILDS IN FROM THE PACIFIC. WITH RIDGING DEVELOPING AT THE SURFACE AND ALOFT...CONDITIONS WILL BE IDEAL FOR INVERSION BUILDING TONIGHT. WITH ABUNDANT MOISTURE TRAPPED WITHIN THE INVERSION EXPECT FOG TO BE FAIRLY WIDESPREAD TONIGHT...BECOMING DENSE IN THE WILLAMETTE VALLEY. A THERMAL TROUGH EXTENDING NORTHWARD FROM THE CALIFORNIA COAST SHOULD INDUCE SOME NORTHERLY FLOW MONDAY...ALLOWING FOR SOME MIXING MOST AREAS. HOWEVER THE NORTHERLY FLOW WILL PROBABLY CAUSE LEFTOVER LOW CLOUDS TO BANK UP AGAINST THE SOUTH END OF THE WILLAMETTE VALLEY...LEADING TO A COOL AND CLAMMY DAY WITH HIGHS AROUND 40 MONDAY AS MOST OTHER AREAS AIM FOR 50 DEGREES...OR AT LEAST THE UPPER 40S IF CLOUDS ARE A BIT PESKIER AS SOME GUIDANCE SUGGESTS. SHOULD BE A NICE DAY IN THE FOOTHILLS AND CASCADES. NORTHERLY FLOW WILL WANE MONDAY NIGHT AND TUESDAY...POSSIBLY ALLOWING SOME FOG TO FORM IN THE VALLEYS AWAY FROM THE WEST END OF THE COLUMBIA GORGE. WITH 12Z MET/MAV GUIDANCE SHOWING LOWER DEWPOINTS OUTLYING VALLEYS...WILL HAVE A BETTER SHOT AT GETTING BELOW FREEZING AND THUS AREAS OF FREEZING FOG TUE MORNING. WITH LIGHT FLOW AND INCREASING HIGH CLOUDS TUESDAY ANY LOW CLOUDS SHOULD BE FAIRLY PERSISTENT AND SLOW TO BURN OFF IN THE STRONGER INVERSION. WHILE VALLEYS REMAIN IN THE UPPER 30S AND 40S...18Z NAM 850 MB TEMPS AROUND +5 TO +6 DEG C SHOULD SUPPORT TEMPS IN THE MID TO UPPER 50S IN THE FOOTHILLS ABOVE THE INVERSION. COASTAL AREAS SHOULD ALSO BE FAIRLY MILD BOTH MONDAY AND TUESDAY. MEANWHILE A SYSTEM PRESENTLY OUT IN THE PACIFIC NEAR 160W SHOULD MERGE WITH A COLD GULF OF ALASKA LOW OVER THE NEXT 24-48 HOURS... EVENTUALLY PUSHING A COLD FRONT FROM THE GULF OF ALASKA SOUTH TOWARD THE PACIFIC NORTHWEST LATE TUESDAY. AT THIS POINT MODEL CONSENSUS SHOWS FAIRLY LIGHT QPF...BUT THERE IS SOME POTENTIAL FOR A WEAK AND BRIEF SUBTROPICAL TAP TO SET UP WITH THIS FRONT. EITHER WAY...RAIN SHOULD SPREAD FROM NORTH TO SOUTH ACROSS THE FORECAST AREA TUE NIGHT AND WED...FOLLOWED BY COLDER AIR WITH SNOW LEVELS FALLING INTO THE COAST RANGE AND FOOTHILL ELEVATIONS BY WED NIGHT. WEAGLE .LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY. THE COLD FRONT WILL CONTINUE TO MOVE THROUGH THE AREA BY LATE WEDNESDAY NIGHT AND PRECIPITATION WILL TAPER OFF LEAVING ONLY A FEW LINGERING SHOWERS BY EARLY THURSDAY MORNING. THIS WILL BE IN THE FORM OF RAIN FOR THE LOWER ELEVATIONS AND SNOW IN THE CASCADES AS THE SNOW LEVELS WILL FALL BEHIND THE FRONT. THERE IS A CHANCE FOR SOME SNOW IN THE HIGHER ELEVATIONS OF THE COAST RANGE...BUT THIS IS DEPENDENT UPON HOW FAST SNOW LEVELS DROP BEFORE THE PRECIP ENDS. THURSDAY WILL BE DRY UNDER NORTHERLY FLOW ALOFT AHEAD OF THE NEXT SYSTEM. TIMING DIFFERENCES REMAIN BETWEEN FORECAST MODELS WITH THE ARRIVAL OF THIS SYSTEM...WITH THE 12Z ECMWF STILL ABOUT 12 HRS FASTER THAN THE GFS. IF THE SYSTEM DOES ARRIVE EARLIER...PRECIP MAY BEGIN AS SNOW FOR AREAS SUCH AS THE COAST RANGE...WILLAPA HILLS... AND CASCADE FOOTHILLS THROUGH EARLY FRIDAY MORNING. HOWEVER...THIS WILL LIKELY BE RAIN FOR MOST OF THE AREA AS SNOW LEVELS QUICKLY RISE...AND SNOW LEVELS SHOULD RISE ABOVE THE CASCADE PASSES BY SATURDAY MORNING. THIS RAIN WILL CONTINUE INTO SATURDAY AND ENHANCED BY A PASSING SHORTWAVE EMBEDDED IN THE UPPER LEVEL FLOW. ANOTHER DISTURBANCE MAY IMPACT THE NORTHERN PARTS OF THE AREA BY SUNDAY... BUT THIS FEATURE IS MUCH WEAKER IN THE 12Z ECMWF. CULLEN && .AVIATION...GENERALLY IFR ALONG THE COAST AND IN THE INTERIOR VALLEYS AS OF 04Z. HOWEVER...NOT NEARLY AS MUCH LIFR COMPARED TO 24 HOURS AGO. LIFR COVERAGE TO INCREASE THROUGH THE NIGHT WITH ABUNDANT LOW LEVEL MOISTURE IN PLACE AND LITTLE IN THE WAY OF WIND. MODELS SHOW A HINT OF N TO NE LOW-LEVEL FLOW DEVELOPING MON AFTERNOON...WITH THE NAM THE MOST PRONOUNCED WITH IT. WOULD EXPECT COASTAL SITES TO BECOME VFR BY AT LEAST 18Z MON...ESPECIALLY KONP. INLAND VALLEYS SHOULD ALSO ACHIEVE VFR CONDITIONS...BUT PROBABLY NOT UNTIL 20Z OR A BIT LATER. THE LOW-LEVEL NLY FLOW MAY KEEP KEUG IN MVFR OR WORSE THE ENTIRE DAY. KPDX AND APPROACHES...IFR TO LIFR CONDITIONS EXPECTED TO PERSIST THROUGH AT LEAST 20Z MON. A BETTER CHANCE OF IMPROVING TO VFR MON AFTERNOON WITH LIGHT LOW-LEVEL NE-E FLOW. WEISHAAR && .MARINE...SEAS AT 00Z WERE RUNNING ABOUT 1-2 FT BELOW ENP GUIDANCE VALID AT 00Z. SHORTLY BEFORE 04Z SEAS HAD RISEN TO 12-14 FT...CLOSE TO THE 06Z ENP FORECAST. THIS LONG-PERIOD SWELL TRAIN WILL CONTINUE THROUGH MON AFTERNOON. SEAS MAY DROP BELOW 10 FT A BIT EARLIER THAN GUIDANCE SUGGESTS...BUT WILL LEAVE THE SMALL CRAFT ADVISORY TIMING AS IS. LITTLE IN THE WAY OF WIND ISSUES FOR THE NEXT COUPLE OF DAYS. MODELS...ESPECIALLY THE NAM...DEVELOP A THERMAL TROUGH ALONG THE SOUTH OREGON COAST LATE TONIGHT THROUGH MON...WHICH COULD PRODUCE SOME N-NE 20 KT GUSTS OVER THE FAR SRN WATERS. BELIEVE THE NAM MAY BE A BIT OVERDONE WITH THIS THERMAL TROUGH FEATURE. ECMWF AND GFS NOT NEARLY AS STRONG WITH IT. ANOTHER WEAK FRONT IS EXPECTED TO PUSH THROUGH THE WATERS LATE TUE. THE MODELS INDICATE LOW END SMALL CRAFT ADVISORY WINDS MAY BE A POSSIBILITY IN THE NW POST FRONTAL WINDS ON WED. IN ADDITION SEAS MAY BUILD BACK NEAR 10 FT WED AND WED NIGHT. WEISHAAR && .PQR WATCHES/WARNINGS/ADVISORIES... OR...NONE. WA...NONE. PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM PST MONDAY FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM. SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST MONDAY. && $$ MORE WEATHER INFORMATION ONLINE AT.. HTTP://WEATHER.GOV/PORTLAND INTERACT WITH US VIA SOCIAL MEDIA WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV WWW.TWITTER.COM/NWSPORTLAND THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1013 AM EST MON DEC 16 2013 .SYNOPSIS... A SERIES OF WEAK LOW PRESSURE SYSTEMS WILL TRACK FROM THE NORTHERN PLAINS THROUGH THE EASTERN UNITED STATES TODAY THROUGH TUESDAY. HIGH PRESSURE WILL BE OVER THE REGION WEDNESDAY AND THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... FORECAST ON TRACK WITH LIGHT SNOW CONFINED TO NW GREENBRIER COUNTY THIS MORNING WITH VERY LITTLE OF SIGNIFICANCE FALLING AS FAR EAST AS LEWISBURG. ADJUSTED SKY/WIND/T/TD GRIDS PER LATEST OBS/SATELLITE. PREVIOUS VALID DISCUSSION AS OF 300 AM EST MONDAY TWO PIECES OF ENERGY COME THROUGH THE NORTHWEST FLOW TODAY AND TONIGHT. FEATURES WERE SUBTLE IN THE WATER VAPOR LOOP BUT EACH HAD AN AREA OF DEEPER MOISTURE. FIRST WAVE ARRIVES EARLY THIS MORNING CROSSING THROUGH WEST VIRGINIA INTO SOUTHERN PENNSYLVANIA BETWEEN 09Z/4AM AND 18Z/1PM. THE NEXT WAVE WILL BE SLIGHTLY STRONGER AND HAS A SURFACE COLD FRONT WITH IT. THIS REACHES THE WESTERN COUNTY WARNING AREA AFTER 06Z/1AM TONIGHT. WILL HAVE BEST PROBABILITY OF PRECIPITATION AS THESE SHORT WAVES CROSS THROUGH. BY TONIGHT SURFACE AND LOW LEVEL WINDS BECOME MORE WEST SO UPSLOPE COMPONENT WILL NOT BE AS FAVORABLE. HIGHEST PROBABILITY WILL REMAIN OVER NORTHWEST SECTIONS OF GREENBRIER COUNTY. LEE CIRRUS WAS FORMING FROM NEW JERSEY TO CENTRAL VIRGINIA AT 2AM. MODELS INDICATED HIGH CLOUDS WILL CONTINUE TO EXPAND EAST OF THE BLUE RIDGE AND SPREAD FARTHER SOUTH ALONG THE MOUNTAINS. STAYED CLOSE TO MAV GUIDANCE FOR WINDS AND TEMPERATURES TODAY AND TONIGHT. && .SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/... AS OF 300 AM EST MONDAY... THE FIRST OF TWO SHORTWAVE TROUGHS WITHIN A LARGER LONGWAVE TROUGH PATTERN WILL MOVE THROUGH THE REGION TUESDAY MORNING. THE SECOND WILL CROSS THE AREA TUESDAY EVENING. THE BULK OF THE ASSOCIATED ENERGY WITH BOTH OF THESE WILL REMAIN NORTH OF THE REGION. HOWEVER...ENOUGH ASSOCIATED MOISTURE...UPPER LEVEL SUPPORT...AND STRONG NORTHWEST FLOW UPSLOPING WILL TAKE PLACE TO ALLOW FOR SOME SNOW SHOWERS ACROSS PARTS OF SOUTHEAST WEST VIRGINIA. MOST OF THE ACCUMULATING SNOW WILL BE CONFINED TO THE PREFERRED UPSLOPE AREAS OF WESTERN GREENBRIER COUNTY WV. ONE TO TWO INCHES OF SNOW WILL BE POSSIBLE IN THIS REGION DURING THIS TIME PERIOD. MODEL GUIDANCE CONTINUE TO SUGGEST THE FORMATION OF A TIGHT PRESSURE GRADIENT OVER THE REGION ALONG WITH 850 MB WINDS IN THE 40 TO 50 KT RANGE. WE WILL STILL FORECAST VERY GUSTY WINDS ACROSS THE MOUNTAINS FROM LATE TUESDAY THROUGH EARLY WEDNESDAY MORNING. SPEEDS WILL BE LESS ACROSS THE PIEDMONT...BUT STILL WITH NOTABLE GUSTS. AFTER THIS TIME...THE WINDS WILL BACK MORE TO THE WEST AND THEN SOUTHWEST AS AN UPPER RIDGE BUILDS OVER THE OHIO VALLEY. THIS WILL BRING AN END TO THE UPSLOPE SNOW SHOWERS OVER SE WV AND A TREND TOWARD LESS CLOUD COVER. SURFACE WINDS WILL BECOME LIGHT AS SURFACE HIGH PRESSURE BUILDS OVER THE REGION. BY THURSDAY...THE SURFACE HIGH WILL SHIFT TO THE COAST...THUS ALLOWING WINDS TO BECOME MORE SOUTHERLY. NO PRECIPITATION IS EXPECTED ON THURSDAY...BUT CLOUD COVER WILL START TO INCREASE WITH THE APPROACH OF A DISTURBANCE THROUGH THE MID-MISSISSIPPI VALLEY. TEMPERATURES WILL BEGIN TO TREND MILDER ON THURSDAY...A TREND THAT WILL CONTINUE THE WEEKEND. && .LONG TERM /FRIDAY THROUGH SUNDAY/... AS OF 253 PM EST SUNDAY... SOUTHWESTERLY FLOW AND INCREASING HEIGHTS WILL BRING TEMPERATURES WARMER THAN NORMAL TEMPERATURES ON FRIDAY. SATURDAY TEMPERATURES COULD ALSO BE WARMER THAN NORMAL...BUT MAY FEEL A LITTLE COOLER WITH PASSING SHOWERS. A COLD FRONT IS EXPECTED TO PASS OVER THE REGION ON SUNDAY. THIS FRONT WILL BRING TEMPERATURES BACK TO SEASONAL LEVELS. FOR THE MOST PART...MODELS ARE IN FAIRLY GOOD AGREEMENT WITH TRACKING A COLD FRONT FROM THE CENTRAL PLAINS ON THURSDAY TO THE EAST COAST ON SUNDAY. MODELS SHOWING WAVES TRACKING ALONG THE FRONT EACH DAY. AS EACH WAVE PASSES...THE FRONT WILL ADVANCE TO THE EAST. THE CHANCE FOR SHOWERS WILL INCREASE ACROSS THE MOUNTAINS ON FRIDAY. POPS INCREASE FOR THE ENTIRE FORECAST AREA ON SATURDAY AS THE FRONT EDGES CLOSER...BUT WILL KEEP CHANCES BETWEEN 30-40 PERCENT. THE BETTER CHANCE FOR SHOWERS WILL BE WITH THE FRONTAL PASSAGE ON SUNDAY. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... AS OF 705 AM EST MONDAY... SHORT WAVE TRACKING OUT OF THE OHIO VALLEY WILL RESULT IN IFR CEILINGS ACROSS SOUTHEAST WEST VIRGINIA...ALONG WITH OCCASIONAL LIGHT SNOW WITH MVFR VISIBILITIES. DOWNSLOPE COMPONENT TO THE WINDS WILL KEEP KROA/KLYH AND KDAN VFR ALTHOUGH WIDESPREAD MID AND HIGH CLOUDS ARE EXPECTED. THIS WAVE WILL PASS THROUGH THE AREA BY EARLY AFTERNOON GIVING A BREAK IN PRECIPITATION TO THE WESTERN UPSLOPE AREAS. HOWEVER...FOLLOWING THIS FEATURE WINDS MAY BRIEFLY GUSTS 15 TO 25 KNOTS. HRRR AND LOCAL WRF MODELS SHOWED REASONABLE TIMING AND LOCATION OF PRECIPITATION THIS MORNING. ANOTHER SHORT WAVE WILL FOLLOW A SIMILAR PATH TONIGHT...REACHING THE AREA AROUND MIDNIGHT. THIS WAVE WILL BRING SNOW BACK INTO KBLF AND KLWB AND WILL PUSH A COLD FRONT THROUGH THE REGION. VERY GUSTY WINDS ARE EXPECTED ON TUESDAY BEHIND THE FRONT. WIND GUSTS OF 20 TO 40 MPH ARE POSSIBLE. THE EXTENDED LOOKS TO FEATURE VFR CONDITIONS KROA/KLYH/KDAN BUT KBCB/KBLF/KLWB WILL BE PERIODICALLY BATTLING UPSLOPE CLOUDS AND SNOW SHOWERS THROUGH WEDNESDAY. WINDS WILL ALSO BE A CONCERN AT ALL SITES THROUGH MID-WEEK. HIGH PRESSURE THEN GAINS CONTROL FOR THE END OF THE WEEK WITH LIGHTER SOUTHWEST WINDS AND VFR CONDITIONS. THINGS WILL BE DETERIORATING FOR THE WEEKEND AS NEXT LOW PRESSURE SYSTEM MOVES IN FROM THE WEST WITH PRECIPITATION AND MVFR OR LOWER CONDITIONS EXPECTED. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS/PC SHORT TERM...DS LONG TERM...RCS AVIATION...AMS/PM
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
712 AM EST MON DEC 16 2013 .SYNOPSIS... A SERIES OF WEAK LOW PRESSURE SYSTEMS WILL TRACK FROM THE NORTHERN PLAINS THROUGH THE EASTERN UNITED STATES TODAY THROUGH TUESDAY. HIGH PRESSURE WILL BE OVER THE REGION WEDNESDAY AND THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM EST MONDAY TWO PIECES OF ENERGY COME THROUGH THE NORTHWEST FLOW TODAY AND TONIGHT. FEATURES WERE SUBTLE IN THE WATER VAPOR LOOP BUT EACH HAD AN AREA OF DEEPER MOISTURE. FIRST WAVE ARRIVES EARLY THIS MORNING CROSSING THROUGH WEST VIRGINIA INTO SOUTHERN PENNSYLVANIA BETWEEN 09Z/4AM AND 18Z/1PM. THE NEXT WAVE WILL BE SLIGHTLY STRONGER AND HAS A SURFACE COLD FRONT WITH IT. THIS REACHES THE WESTERN COUNTY WARNING AREA AFTER 06Z/1AM TONIGHT. WILL HAVE BEST PROBABILITY OF PRECIPITATION AS THESE SHORT WAVES CROSS THROUGH. BY TONIGHT SURFACE AND LOW LEVEL WINDS BECOME MORE WEST SO UPSLOPE COMPONENT WILL NOT BE AS FAVORABLE. HIGHEST PROBABILITY WILL REMAIN OVER NORTHWEST SECTIONS OF GREENBRIER COUNTY. LEE CIRRUS WAS FORMING FROM NEW JERSEY TO CENTRAL VIRGINIA AT 2AM. MODELS INDICATED HIGH CLOUDS WILL CONTINUE TO EXPAND EAST OF THE BLUE RIDGE AND SPREAD FARTHER SOUTH ALONG THE MOUNTAINS. STAYED CLOSE TO MAV GUIDANCE FOR WINDS AND TEMPERATURES TODAY AND TONIGHT. && .SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/... AS OF 300 AM EST MONDAY... THE FIRST OF TWO SHORTWAVE TROUGHS WITHIN A LARGER LONGWAVE TROUGH PATTERN WILL MOVE THROUGH THE REGION TUESDAY MORNING. THE SECOND WILL CROSS THE AREA TUESDAY EVENING. THE BULK OF THE ASSOCIATED ENERGY WITH BOTH OF THESE WILL REMAIN NORTH OF THE REGION. HOWEVER...ENOUGH ASSOCIATED MOISTURE...UPPER LEVEL SUPPORT...AND STRONG NORTHWEST FLOW UPSLOPING WILL TAKE PLACE TO ALLOW FOR SOME SNOW SHOWERS ACROSS PARTS OF SOUTHEAST WEST VIRGINIA. MOST OF THE ACCUMULATING SNOW WILL BE CONFINED TO THE PREFERRED UPSLOPE AREAS OF WESTERN GREENBRIER COUNTY WV. ONE TO TWO INCHES OF SNOW WILL BE POSSIBLE IN THIS REGION DURING THIS TIME PERIOD. MODEL GUIDANCE CONTINUE TO SUGGEST THE FORMATION OF A TIGHT PRESSURE GRADIENT OVER THE REGION ALONG WITH 850 MB WINDS IN THE 40 TO 50 KT RANGE. WE WILL STILL FORECAST VERY GUSTY WINDS ACROSS THE MOUNTAINS FROM LATE TUESDAY THROUGH EARLY WEDNESDAY MORNING. SPEEDS WILL BE LESS ACROSS THE PIEDMONT...BUT STILL WITH NOTABLE GUSTS. AFTER THIS TIME...THE WINDS WILL BACK MORE TO THE WEST AND THEN SOUTHWEST AS AN UPPER RIDGE BUILDS OVER THE OHIO VALLEY. THIS WILL BRING AN END TO THE UPSLOPE SNOW SHOWERS OVER SE WV AND A TREND TOWARD LESS CLOUD COVER. SURFACE WINDS WILL BECOME LIGHT AS SURFACE HIGH PRESSURE BUILDS OVER THE REGION. BY THURSDAY...THE SURFACE HIGH WILL SHIFT TO THE COAST...THUS ALLOWING WINDS TO BECOME MORE SOUTHERLY. NO PRECIPITATION IS EXPECTED ON THURSDAY...BUT CLOUD COVER WILL START TO INCREASE WITH THE APPROACH OF A DISTURBANCE THROUGH THE MID-MISSISSIPPI VALLEY. TEMPERATURES WILL BEGIN TO TREND MILDER ON THURSDAY...A TREND THAT WILL CONTINUE THE WEEKEND. && .LONG TERM /FRIDAY THROUGH SUNDAY/... AS OF 253 PM EST SUNDAY... SOUTHWESTERLY FLOW AND INCREASING HEIGHTS WILL BRING TEMPERATURES WARMER THAN NORMAL TEMPERATURES ON FRIDAY. SATURDAY TEMPERATURES COULD ALSO BE WARMER THAN NORMAL...BUT MAY FEEL A LITTLE COOLER WITH PASSING SHOWERS. A COLD FRONT IS EXPECTED TO PASS OVER THE REGION ON SUNDAY. THIS FRONT WILL BRING TEMPERATURES BACK TO SEASONAL LEVELS. FOR THE MOST PART...MODELS ARE IN FAIRLY GOOD AGREEMENT WITH TRACKING A COLD FRONT FROM THE CENTRAL PLAINS ON THURSDAY TO THE EAST COAST ON SUNDAY. MODELS SHOWING WAVES TRACKING ALONG THE FRONT EACH DAY. AS EACH WAVE PASSES...THE FRONT WILL ADVANCE TO THE EAST. THE CHANCE FOR SHOWERS WILL INCREASE ACROSS THE MOUNTAINS ON FRIDAY. POPS INCREASE FOR THE ENTIRE FORECAST AREA ON SATURDAY AS THE FRONT EDGES CLOSER...BUT WILL KEEP CHANCES BETWEEN 30-40 PERCENT. THE BETTER CHANCE FOR SHOWERS WILL BE WITH THE FRONTAL PASSAGE ON SUNDAY. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... AS OF 705 AM EST MONDAY... SHORT WAVE TRACKING OUT OF THE OHIO VALLEY WILL RESULT IN IFR CEILINGS ACROSS SOUTHEAST WEST VIRGINIA...ALONG WITH OCCASIONAL LIGHT SNOW WITH MVFR VISIBILITIES. DOWNSLOPE COMPONENT TO THE WINDS WILL KEEP KROA/KLYH AND KDAN VFR ALTHOUGH WIDESPREAD MID AND HIGH CLOUDS ARE EXPECTED. THIS WAVE WILL PASS THROUGH THE AREA BY EARLY AFTERNOON GIVING A BREAK IN PRECIPITATION TO THE WESTERN UPSLOPE AREAS. HOWEVER...FOLLOWING THIS FEATURE WINDS MAY BRIEFLY GUSTS 15 TO 25 KNOTS. HRRR AND LOCAL WRF MODELS SHOWED REASONABLE TIMING AND LOCATION OF PRECIPITATION THIS MORNING. ANOTHER SHORT WAVE WILL FOLLOW A SIMILAR PATH TONIGHT...REACHING THE AREA AROUND MIDNIGHT. THIS WAVE WILL BRING SNOW BACK INTO KBLF AND KLWB AND WILL PUSH A COLD FRONT THROUGH THE REGION. VERY GUSTY WINDS ARE EXPECTED ON TUESDAY BEHIND THE FRONT. WIND GUSTS OF 20 TO 40 MPH ARE POSSIBLE. THE EXTENDED LOOKS TO FEATURE VFR CONDITIONS KROA/KLYH/KDAN BUT KBCB/KBLF/KLWB WILL BE PERIODICALLY BATTLING UPSLOPE CLOUDS AND SNOW SHOWERS THROUGH WEDNESDAY. WINDS WILL ALSO BE A CONCERN AT ALL SITES THROUGH MID-WEEK. HIGH PRESSURE THEN GAINS CONTROL FOR THE END OF THE WEEK WITH LIGHTER SOUTHWEST WINDS AND VFR CONDITIONS. THINGS WILL BE DETERIORATING FOR THE WEEKEND AS NEXT LOW PRESSURE SYSTEM MOVES IN FROM THE WEST WITH PRECIPITATION AND MVFR OR LOWER CONDITIONS EXPECTED. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...DS LONG TERM...RCS AVIATION...AMS/PM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1045 AM CST TUE DEC 17 2013 .UPDATE... ISSUED AT 1045 AM CST TUE DEC 17 2013 AFTER COLLABORATION WITH MPX...HAVE ISSUED WINTER WEATHER ADVISORIES FOR SOUTHEAST MN AND TAYLOR/CLARK IN WI. IN THE CASE OF SOUTHEAST MN...ALTHOUGH SNOW SHOWER COVERAGE THERE LOOKS TO BE ISOLATED AT BEST...THERE ARE ALREADY REPORTS OF BLOWING AND DRIFTING SNOW IN DODGE COUNTY...ALONG WITH AN ACCIDENT ON US-14 JUST WEST OF ROCHESTER. WITH NORTHWEST WINDS STRONGEST ACROSS SOUTHEAST MN THROUGH THE AFTERNOON HOURS...LIKELY SUSTAINED AROUND 20 KT WITH GUSTS UPWARDS OF 30 KT...ANTICIPATING MORE BLOWING AND DRIFTING THROUGH THE AFTERNOON. THIS COULD EASILY LEAD TO MORE ACCIDENTS. IN THE CASE OF TAYLOR/CLARK...RAISED PRECIPITATION CHANCES UP ABOUT 30 PERCENT AND MAY NEED TO RAISE MORE AS SNOW SHOWERS ARE EXPANDING IN COVERAGE ACROSS NORTHERN WISCONSIN. IN ADDITION...KDLH RADAR SHOWS A CONVERGENT BAND OF SNOW ALONG A SURFACE TROUGH HEADING INTO NORTHWEST WI...WHICH WILL LIKELY IMPACT TAYLOR/CLARK COUNTIES THIS AFTERNOON. ON TOP OF ALL THIS...THE NORTHWEST WINDS ARE PICKING UP THERE WHICH COULD LEAD TO PATCHES OF BLOWING SNOW. SO A COMBINATION HERE OF SNOW AND BLOWING SNOW COULD LEAD TO ACCIDENTS. ELSEWHERE...PRECIPITATION CHANCES HAVE GENERALLY BEEN RAISED NORTH OF I-90 WITH DIURNAL SNOW SHOWERS EXPECTED IN A COLD ADVECTION REGIME NOW IN PLACE. DID HAVE TO BOOST SOME TEMPERATURES UP THROUGH THE EARLY AFTERNOON HOURS AS READINGS ROSE A BIT MORE THAN EXPECTED. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 408 AM CST TUE DEC 17 2013 FORECAST CONCERNS ARE ON SNOW CHANCES TODAY. FOCUS THEN QUICKLY TURNS TO STORM SYSTEM IMPACTING THE REGION THURSDAY INTO THURSDAY NIGHT WITH THE POTENTIAL FOR LIGHT FREEZING RAIN AND SNOW. AT 3 AM...WATER VAPOR IMAGERY SHOWED A WEAK SHORTWAVE PUSHING ACROSS THE FORECAST AREA PRODUCING LIGHT SNOW AS IT MOVES THROUGH. THE WAVE WILL EXIT THE AREA QUICKLY THIS MORNING BUT ANOTHER WAVE WAS RIGHT BEHIND THE FIRST AND WAS MOVING ACROSS EASTERN NORTH DAKOTA. THIS SECOND WAVE WILL BRING COLDER AIR ALOFT WITH IT...WITH 850 MB TEMPERATURES GOING FROM -7C OVER THE AREA EARLY THIS MORNING TO -17C BY LATE THIS AFTERNOON. THIS COLDER AIR ALOFT WILL STEEPEN THE 1000-850 MB LAPSE RATES...LEADING TO SCATTERED SNOW SHOWERS AND GUSTY WINDS FROM LATE THIS MORNING THROUGH THE AFTERNOON HOURS. THE MOISTURE LOOKS LIMITED OVER SOUTHEAST MINNESOTA AND NORTHEAST IOWA...ESPECIALLY WEST OF HIGHWAY 52. AREAS EAST OF HIGHWAY 52 THROUGH WESTERN INTO CENTRAL WISCONSIN CAN EXPECT A FEW PASSING SNOW SHOWERS TODAY WITH THE POTENTIAL TO PICK UP A FEW TENTHS OF ACCUMULATION. LOCATIONS OVER CENTRAL INTO NORTH CENTRAL WISCONSIN HAVE THE BEST CHANCES OF SEEING SOME LIGHT ACCUMULATIONS. OTHERWISE...NORTHWEST WINDS WILL PICK UP TODAY INTO THE 15 TO 25 MPH RANGE WITH SOME GUSTS AROUND 35 MPH OVER THE OPEN AREAS OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA. THESE WINDS WILL PRODUCE SOME PATCHY BLOWING SNOW AND AREAS OF DRIFTING SNOW WHICH COULD LEAD TO SOME SLICK SPOTS ON AREA ROADS. HIGH PRESSURE MOVES OVER THE REGION TONIGHT WITH QUIET WEATHER EXPECTED. PLAN ON A CHILLY NIGHT WITH LOWS RANGING FROM THE SINGLE DIGITS BELOW ZERO OVER NORTH CENTRAL WISCONSIN TO THE TEENS ACROSS NORTHEAST IOWA. THESE LOWS SHOULD OCCUR EARLY IN THE NIGHT. A WARM FRONT THEN PUSHES ACROSS THE UPPER MISSISSIPPI RIVER VALLEY LATE TONIGHT INTO EARLY WEDNESDAY MORNING AS A TROUGH DIVES INTO THE THE WEST COAST. TEMPERATURES ARE EXPECTED TO GRADUALLY RISE EARLY WEDNESDAY MORNING IN THE WAKE OF THE FRONT. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 408 AM CST TUE DEC 17 2013 LOW PRESSURE WILL DEVELOP OVER THE NORTHERN PLAINS ON WEDNESDAY...LEADING TO A TIGHT PRESSURE GRADIENT OVER THE UPPER MISSISSIPPI RIVER VALLEY. SOUTH/SOUTHWEST WINDS AHEAD OF THE LOW WILL HELP TO USHER IN A WARMER AIRMASS. 850 MB TEMPERATURES START OUT AT - 3C EARLY WEDNESDAY MORNING BUT THEN WARM TO +7C BY EARLY WEDNESDAY EVENING. THE WARM AIR STAYS WELL ALOFT THROUGH THE DAY BUT WE SHOULD STILL SEE HIGH TEMPERATURES WARM INTO THE 30S ACROSS MUCH OF THE FORECAST AREA. THE ONLY EXCEPTION WILL BE OVER NORTH CENTRAL WISCONSIN WHERE HIGHS ARE EXPECTED TO REACH INTO THE MID 20S. A FRONTAL BOUNDARY THEN SLIDES SOUTH ACROSS THE AREA LATE WEDNESDAY NIGHT INTO THURSDAY MORNING AS A TROUGH CONTINUES TO DEEPEN OVER THE SOUTHWEST CONUS. THE FRONT IS EXPECTED TO STALL OVER CENTRAL IOWA THROUGH SOUTH CENTRAL WISCONSIN. THE BOUNDARY WILL INTERACT WITH A SHORTWAVE MOVING ACROSS THE NORTHERN PLAINS AND THE RIGHT ENTRANCE REGION OF A 250 MB JET TO PRODUCE LIGHT SNOW AND FREEZING DRIZZLE FROM THURSDAY AFTERNOON THROUGH THURSDAY NIGHT. FORECAST SOUNDINGS SHOW ICE ALOFT FOR LOCATIONS NORTH OF INTERSTATE 90 BY THE TIME THE PRECIPITATION DEVELOPS LATE IN THE AFTERNOON. HOWEVER...FOR AREAS SOUTH OF INTERSTATE 90 THERE ISN/T ICE ALOFT WITH SOUNDINGS SHOWING A NEARLY SATURATED LAYER FROM THE SURFACE THROUGH 2KFT WITH WEAK OMEGA WITHIN THIS LAYER. THIS SHOULD LEAD TO AREAS OF FREEZING DRIZZLE OVER NORTHEAST IOWA INTO SOUTHWEST WISCONSIN EARLY THURSDAY MORNING. THE FREEZING DRIZZLE SHOULD GRADUALLY SWITCH OVER TO SNOW THURSDAY NIGHT AS COOLER AIR MOVES IN FROM THE NORTH AND SATURATION OCCURS ALOFT. WILL HAVE TO KEEP A VERY CLOSE EYE ON THE FORECAST MODELS THE NEXT FEW RUNS. THE ECMWF/GEM/GFS ARE IN AGREEMENT WITH THIS SCENARIO BUT THE NAM IS SHOWING THE FREEZING DRIZZLE DEVELOPING LATE WEDNESDAY NIGHT OVER NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN. THE 17.06 NAM IS NOW SHOWING A DRIZZLE SIGNATURE IN THE QPF FIELDS OVER THESE AREAS. WILL LEAN TOWARD THE ECMWF/GEM/GFS. HEADLINES MAY BE NEEDED OVER THESE AREAS FOR LIGHT ICE ACCUMULATIONS WHICH COULD LEAD TO DANGEROUS TRAVEL CONDITIONS. FORECAST MODELS ARE ALSO TRENDING A LITTLE COOLER WITH TEMPERATURES ON THURSDAY WITH MOST OF THE AREA NOT GETTING ABOVE THE FREEZING MARK...WHICH RAISES ADDITIONAL CONCERN FOR THE FREEZING DRIZZLE POTENTIAL. PLAN ON AREAS OF FOG WEDNESDAY NIGHT THROUGH THURSDAY FOR AREAS ALONG AND SOUTH OF INTERSTATE 90. THE FOG MAY BE DENSE AT TIMES...ESPECIALLY ACROSS NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN. THE PRECIPITATION SHOULD TURN OVER TO ALL SNOW BY EARLY FRIDAY MORNING. AT THIS TIME IT APPEARS SNOW ACCUMULATIONS OF 1 TO 3 INCHES ARE POSSIBLE ALONG AND NORTH OF I-90. A GLAZE TO AROUND A TENTH OF AN INCH OF ICING IS POSSIBLE SOUTH OF I-90. ONCE THE FREEZING DRIZZLE SWITCHES OVER TO SNOW...ACCUMULATIONS OF AROUND 1/2 INCH ARE POSSIBLE. THERE IS CONSIDERABLE UNCERTAINTY REGARDING THE TIMING AND PLACEMENT OF THE PRECIPITATION SO WILL HAVE TO KEEP A CLOSE EYE ON MODEL TRENDS TODAY AND TONIGHT. PRECIPITATION WILL END EARLY ON FRIDAY AS THE SYSTEM EXITS. SLIGHTLY COOLER TEMPERATURES MOVE BACK INTO THE REGION FOR THIS WEEKEND WITH HIGHS IN THE UPPER TEENS TO MID 20S BOTH FRIDAY AND SATURDAY. PLAN ON OVERNIGHT LOWS DIPPING INTO THE SINGLE DIGITS. A FEW WEAK DISTURBANCES COULD BRING SOME LIGHT SNOW TO THE AREA BUT ACCUMULATIONS APPEAR MINOR AT THIS TIME. A STRONGER SYSTEM THEN LIFTS NORTHEAST OUT OF MEXICO SATURDAY AND HEADS FOR THE OHIO RIVER VALLEY LATE SATURDAY NIGHT INTO SUNDAY MORNING. THIS SYSTEM WILL JUST GLANCE SOUTHWEST SECTIONS OF THE FORECAST AREA BRINGING LIGHT SNOW TO PORTIONS OF NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN. THERE WILL BE A BREAK IN THE PRECIPITATION CHANCES SUNDAY NIGHT BEFORE ANOTHER WEAK SYSTEM MOVES THROUGH ON MONDAY BRINGING SLIGHT CHANCES FOR LIGHT SNOW. IT WILL REMAIN ON THE COOL SIDE FOR THIS TIME OF YEAR GOING INTO NEXT WEEK WITH HIGHS IN THE TEENS AND LOWS IN THE SINGLE DIGITS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1140 PM CST MON DEC 16 2013 THE NEXT BAND OF LIGHT SNOW WAS STARTING TO TAKE SHAPE OVER CENTRAL AND NORTHERN MINNESOTA. THE SHORT WAVE TROUGH WITH THIS BAND OF SNOW LOOKS TO TRACK FARTHER TO THE NORTH THAN PREVIOUSLY EXPECTED. THIS HAS RESULTED IN A NORTHWARD SHIFT OF WHERE THE SNOW SHOULD FALL AS WELL AND IT NOW COULD BE QUITE POSSIBLE THAT NEITHER TAF SITE COULD SEE ANY SNOW. KLSE LOOKS TO HAVE A SLIGHTLY BETTER CHANCE OF BEING BRUSHED BY THE SOUTHERN EXTENT OF THE SNOW BAND AND HAVE SHOWN A SHORT PERIOD OF PREVAILING MVFR WITH THE POSSIBILITY OF IFR...BUT CONFIDENCE IS NOT HIGH IN THIS AT ALL. FOR KRST...HAVE GONE TO PREVAILING VFR OVERNIGHT WITH A POSSIBILITY OF MVFR IF THE SNOW BAND CAN REACH THE AIRPORT. THE SNOW CHANCES WILL END BEFORE SUNRISE AS A COLD FRONT GOES THROUGH. THE 17.00Z NAM AND 18.03Z RAP NOW BOTH SHOW THE INVERSION HOLDING TOUGH BEHIND THE FRONT UNTIL MID MORNING. ONCE THE INVERSION MIXES OUT...GOOD LOW LEVEL LAPSE RATES DEVELOP THAT WILL ALLOW FOR SUSTAINED NORTHWEST WINDS BETWEEN 15 AND 20 KNOTS WITH GUSTS OF BETWEEN 25 AND 30 KT. THIS WILL LIKELY PRODUCE A LOT OF DRIFTING SNOW AND POSSIBLY A LITTLE BIT OF BLOWING SNOW AT KRST. THERE SHOULD ALSO BE ENOUGH RESIDUAL LOW LEVEL MOISTURE TO ALLOW A MVFR CEILING TO DEVELOP ON TOP OF THE INSTABILITY LAYER. THE INVERSION WILL REDEVELOP EARLY TUESDAY EVENING ALLOWING THE WINDS TO SETTLE DOWN TO AROUND 10 KNOTS ENDING THE BLOWING SNOW AND MVFR CEILINGS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR WIZ017- 029. MN...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR MNZ079- 086-087-094-095. IA...NONE. && $$ UPDATE...AJ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1159 AM CST MON DEC 16 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 329 AM CST MON DEC 16 2013 MONITORING DYNAMIC SYSTEM NEAR LAKE WINNIPEG AND THE RADAR BAND DEVELOPING ACROSS ND AT 08Z. OTHER RADAR ECHO AND SOME SCT REPORTS OF SN- BEING REPORTED ALONG WARM ADVECTION ARM EXTENDING THROUGH THE EASTERN DAKOTAS AND INTO THE MN RIVER VALLEY. THIS SYSTEM WAS HANDLED WELL AND FEW CHANGES WERE MADE TO THE ONGOING FORECAST FOR TODAY EXCEPT FOR TIMING. STRONG CIRCULATION CLEARLY SEEN IN GOES WATER VAPOR IMAGERY NEAR LAKE WINNIPEG AND THIS SYSTEM AND ITS POTENTIAL VORTICITY ADVECTION WILL DIG TOWARD LAKE SUPERIOR AND DRAG GOOD DYNAMICS ACROSS NORTHERN WI TODAY. THIS POTENTIAL VORTICITY ADVECTION...IN COMBINATION WITH WARM ADVECTION ALONG THE THERMAL RIBBON FROM 700-900 MB...AND SOME MODERATE 250MB JET EXIT REGION DIVERGENCE WILL PRODUCE A SWATH OF 1-2 SNOW TODAY. HRRR TRENDS SHOW A SOMEWHAT NARROW BAND SHIFTING ACROSS WI DURING THE DAY...WITH ABOUT 2 HOURS OF SNOW AT ANY ONE POINT. HI-RES WINDOWS FROM NCEP NMM/ARW 16.00Z RUNS SUGGEST SIMILAR TIMING TODAY AND INTENSITY...BUT MAYBEA BIT WIDER BAND. A BREAK OCCURS LATE TODAY AND THIS EVENING...BUT HAVE INCREASED THE SNOW CHANCES TONIGHT WITH ANOTHER 1-2 INCHES NOW EXPECTED ALONG AND NORTH OF I-90. SECONDARY SHORTWAVE TROUGH RIDING ON THE NOSE OF THE POLAR JET WILL COME ACROSS THE AREA TONIGHT...A DIRECT HIT. SO...SNOWFALL SHOULD BREAK OUT AGAIN ALONG AND NORTH OF I-90 AROUND MIDNIGHT...WITH AREAS SOUTH A BIT MORE LIMITED IN THEIR SATURATION. THE ENERGY WILL SHIFT EAST BY SUNRISE. MODEL GUIDANCE HAS SOME SPREAD ON THE LOCATION OF THE SNOW WITH SOME SOLUTIONS FURTHER SOUTH...BUT IT SEEMS THE TRACK OF THE WAVE AND THE JET FLOW ALOFT WOULD SHOW PREFERENCE TO THE I-90 CORRIDOR AND NORTH. NEW SNOW TOTALS BY TUESDAY MORNING WILL BE IN THE 1-3 INCH RANGE WITH THE 3 INCH TOTALS MOST LIKELY ALONG AND NORTH OF I-94. HAVE COLLABORATED WITH SURROUNDING NWS OFFICES AND WILL HOLD OFF ON THE ADVISORY AS THE TWO SYSTEMS SHOULD BE SPACED IN TIME...AND THE 3 INCH TOTALS SHOULD BE THE HIGHER END RATHER THAN THE RULE. WILL COVER IT IN THE HAZ WEATHER OUTLOOK AND POSSIBLY A SPECIAL STATEMENT. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 329 AM CST MON DEC 16 2013 TUESDAY LOOKS TO BE A BREEZY DAY BEHIND THIS WAVE...IN THE 15-25 MPH RANGE. THEN...RIDGE BUILDING STARTS WITH MAINLY SUNSHINE EXCEPT ACROSS THE NORTH WHERE THE STORM TRACK SHIFT TO. A STRONG SHORTWAVE TRAVELS ALONG THE U.S. CANADA BORDER AND MORE WARM ADVECTION IS EXPECTED TUESDAY NIGHT AND WEDNESDAY NIGHT...WITH PRECIPITATION STILL OFF TO THE NORTH. THURSDAY-SUNDAY... SIGNALS CONTINUE IN THE MODEL GUIDANCE FOR PRECIPITATION TO SPREAD IN LATE THURSDAY AND THURSDAY NIGHT WITH THE FIRST SHORTWAVE TROUGH EJECTION FROM THE LONGWAVE DEVELOPING ACROSS THE WRN CONUS. THE SIGNAL IS REMAINING CONSISTENT WITH THE GFS AND GFS ENSEMBLES STILL THE COLDER SOLUTIONS...WITH THE FRONTAL BOUNDARY REMAINING THROUGH IL AND THE SOUTHERN FORECAST AREA IN SUB-ZERO SURFACE TEMPERATURES. ACROSS ABOUT THE SOUTHERN TWO-THIRDS...THE LIFT APPEARS LIMITED WITH ABUNDANT MOISTURE IN THE 0-3KM LAYER...BUT NOT ABOVE IN THE ICE PRODUCING LAYER. THUS THE GFS HAS A 3KM DEEP SUPERCOOLED LIQUID LAYER...CONSISTENT OVER THE PAST RUNS. THIS IS A FZDZ/FZRA SITUATION AND HOLD THE POTENTIAL FOR ICING. THE WARMER SOLUTIONS OF THE ECMWF/CANADIAN MODELS WOULD CAUSE RAIN IN THE SOUTH. THE SPREAD IN THE TEMPERATURE PROFILE IS STILL VERY LARGE THURSDAY/THU NIGHT AMONG THE WARM VERSUS COLD SOLUTIONS...WITH SURFACE HIGHS 28F IN THE GFS THURSDAY...AND 45F IN THE CANADIAN MODEL...WITH THE 16.00Z ECMWF IN THE MIDDLE. THAT IS WHERE OUR FORECAST TEMPERATURES REMAIN...THUS A MORE LIMITED ICING AREA IN NERN IA AND SWRN WI...AND AMOUNTS HAVE TRENDED LOWER...LESS THAN 0.10 INCHES. TO THE NORTH ON THURSDAY NIGHT IT APPEARS THE NORTHERN STREAM WAVE WILL PROVIDE ENOUGH FORCING FOR DEEP SATURATION AND LIGHT SNOWFALL THAT WOULD ACCUMULATE AROUND AN INCH. CURRENT FORECAST HAS THIS LIQUID VERSUS SNOW OUTCOME ALONG A KMCW-KISW LINE...WITH SNOW NORTHWEST. OVERALL...DID RAISE PRECIPITATION CHANCES BUT OVERALL CHANGES WERE MINOR WITH THAT SYSTEM. THE LONGWAVE TROUGH DIGS DEEPLY INTO MEXICO ON THE WEEKEND AND THERE IS HIGH SPREAD ON THE OUTCOMES FOR THIS MAJOR ENERGY. THERE WILL BE MAJOR WINTER WEATHER WITH THIS SYSTEM...BUT THE FURTHER SOUTH IT DIGS...THE MORE THE AREA WOULD SEEM TO REMAIN UNDER THE NRN STREAM OF ENERGY AND NOT BE AFFECTED. HAVE SMALL CHANCES OF PRECIPITATION IN THE FORECAST FOR NOW MAINLY FOR E/SE AREAS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1158 AM CST MON DEC 16 2013 CURRENTLY WATCHING A TROUGH OF LOW PRESSURE AND ASSOCIATED N-S BAND OF MODERATE TO OCCASIONALLY HEAVY SNOW MOVING EAST ACROSS THE MISSISSIPPI RIVER AT THIS TIME. SNOW SHOULD END AT KRST BY 20Z AND AT KLSE BY 22Z WITH CIGS/VIS IMPROVING INTO MVFR CATEGORY. PLAN ON MVFR STRATOCUMULUS TO LINGER INTO THIS EVENING. ANOTHER FAIRLY POTENT TROUGH OF LOW PRESSURE IS POISED TO IMPACT THE AREA AFTER MIDNIGHT WITH ANOTHER ROUND OF LIGHT TO MODERATE SNOW WITH VIS/CIGS DROPPING BACK INTO IFR/TEMPO LIFR CATEGORY IN THE 07-11Z TIME FRAME. IN ADDITION...LOOKS LIKE THIS TROUGH WILL BRING SOME GUSTY NORTHWEST WINDS BEHIND IT. PLAN ON NORTHWEST WINDS IN THE 20-30KT RANGE AT KRST AFTER 11Z...AND AT KLSE AFTER 12Z. THESE WINDS OVER A FALLING/FRESH SNOW IS EXPECTED TO PRODUCE SOME BLOWING SNOW ACROSS THE OPEN AREAS OF SOUTHEAST MN...INLUDING KRST. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BAUMGARDT LONG TERM...BAUMGARDT AVIATION...DAS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
602 AM CST MON DEC 16 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 329 AM CST MON DEC 16 2013 MONITORING DYNAMIC SYSTEM NEAR LAKE WINNIPEG AND THE RADAR BAND DEVELOPING ACROSS ND AT 08Z. OTHER RADAR ECHO AND SOME SCT REPORTS OF SN- BEING REPORTED ALONG WARM ADVECTION ARM EXTENDING THROUGH THE EASTERN DAKOTAS AND INTO THE MN RIVER VALLEY. THIS SYSTEM WAS HANDLED WELL AND FEW CHANGES WERE MADE TO THE ONGOING FORECAST FOR TODAY EXCEPT FOR TIMING. STRONG CIRCULATION CLEARLY SEEN IN GOES WATER VAPOR IMAGERY NEAR LAKE WINNIPEG AND THIS SYSTEM AND ITS POTENTIAL VORTICITY ADVECTION WILL DIG TOWARD LAKE SUPERIOR AND DRAG GOOD DYNAMICS ACROSS NORTHERN WI TODAY. THIS POTENTIAL VORTICITY ADVECTION...IN COMBINATION WITH WARM ADVECTION ALONG THE THERMAL RIBBON FROM 700-900 MB...AND SOME MODERATE 250MB JET EXIT REGION DIVERGENCE WILL PRODUCE A SWATH OF 1-2 SNOW TODAY. HRRR TRENDS SHOW A SOMEWHAT NARROW BAND SHIFTING ACROSS WI DURING THE DAY...WITH ABOUT 2 HOURS OF SNOW AT ANY ONE POINT. HI-RES WINDOWS FROM NCEP NMM/ARW 16.00Z RUNS SUGGEST SIMILAR TIMING TODAY AND INTENSITY...BUT MAYBEA BIT WIDER BAND. A BREAK OCCURS LATE TODAY AND THIS EVENING...BUT HAVE INCREASED THE SNOW CHANCES TONIGHT WITH ANOTHER 1-2 INCHES NOW EXPECTED ALONG AND NORTH OF I-90. SECONDARY SHORTWAVE TROUGH RIDING ON THE NOSE OF THE POLAR JET WILL COME ACROSS THE AREA TONIGHT...A DIRECT HIT. SO...SNOWFALL SHOULD BREAK OUT AGAIN ALONG AND NORTH OF I-90 AROUND MIDNIGHT...WITH AREAS SOUTH A BIT MORE LIMITED IN THEIR SATURATION. THE ENERGY WILL SHIFT EAST BY SUNRISE. MODEL GUIDANCE HAS SOME SPREAD ON THE LOCATION OF THE SNOW WITH SOME SOLUTIONS FURTHER SOUTH...BUT IT SEEMS THE TRACK OF THE WAVE AND THE JET FLOW ALOFT WOULD SHOW PREFERENCE TO THE I-90 CORRIDOR AND NORTH. NEW SNOW TOTALS BY TUESDAY MORNING WILL BE IN THE 1-3 INCH RANGE WITH THE 3 INCH TOTALS MOST LIKELY ALONG AND NORTH OF I-94. HAVE COLLABORATED WITH SURROUNDING NWS OFFICES AND WILL HOLD OFF ON THE ADVISORY AS THE TWO SYSTEMS SHOULD BE SPACED IN TIME...AND THE 3 INCH TOTALS SHOULD BE THE HIGHER END RATHER THAN THE RULE. WILL COVER IT IN THE HAZ WEATHER OUTLOOK AND POSSIBLY A SPECIAL STATEMENT. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 329 AM CST MON DEC 16 2013 TUESDAY LOOKS TO BE A BREEZY DAY BEHIND THIS WAVE...IN THE 15-25 MPH RANGE. THEN...RIDGE BUILDING STARTS WITH MAINLY SUNSHINE EXCEPT ACROSS THE NORTH WHERE THE STORM TRACK SHIFT TO. A STRONG SHORTWAVE TRAVELS ALONG THE U.S. CANADA BORDER AND MORE WARM ADVECTION IS EXPECTED TUESDAY NIGHT AND WEDNESDAY NIGHT...WITH PRECIPITATION STILL OFF TO THE NORTH. THURSDAY-SUNDAY... SIGNALS CONTINUE IN THE MODEL GUIDANCE FOR PRECIPITATION TO SPREAD IN LATE THURSDAY AND THURSDAY NIGHT WITH THE FIRST SHORTWAVE TROUGH EJECTION FROM THE LONGWAVE DEVELOPING ACROSS THE WRN CONUS. THE SIGNAL IS REMAINING CONSISTENT WITH THE GFS AND GFS ENSEMBLES STILL THE COLDER SOLUTIONS...WITH THE FRONTAL BOUNDARY REMAINING THROUGH IL AND THE SOUTHERN FORECAST AREA IN SUB-ZERO SURFACE TEMPERATURES. ACROSS ABOUT THE SOUTHERN TWO-THIRDS...THE LIFT APPEARS LIMITED WITH ABUNDANT MOISTURE IN THE 0-3KM LAYER...BUT NOT ABOVE IN THE ICE PRODUCING LAYER. THUS THE GFS HAS A 3KM DEEP SUPERCOOLED LIQUID LAYER...CONSISTENT OVER THE PAST RUNS. THIS IS A FZDZ/FZRA SITUATION AND HOLD THE POTENTIAL FOR ICING. THE WARMER SOLUTIONS OF THE ECMWF/CANADIAN MODELS WOULD CAUSE RAIN IN THE SOUTH. THE SPREAD IN THE TEMPERATURE PROFILE IS STILL VERY LARGE THURSDAY/THU NIGHT AMONG THE WARM VERSUS COLD SOLUTIONS...WITH SURFACE HIGHS 28F IN THE GFS THURSDAY...AND 45F IN THE CANADIAN MODEL...WITH THE 16.00Z ECMWF IN THE MIDDLE. THAT IS WHERE OUR FORECAST TEMPERATURES REMAIN...THUS A MORE LIMITED ICING AREA IN NERN IA AND SWRN WI...AND AMOUNTS HAVE TRENDED LOWER...LESS THAN 0.10 INCHES. TO THE NORTH ON THURSDAY NIGHT IT APPEARS THE NORTHERN STREAM WAVE WILL PROVIDE ENOUGH FORCING FOR DEEP SATURATION AND LIGHT SNOWFALL THAT WOULD ACCUMULATE AROUND AN INCH. CURRENT FORECAST HAS THIS LIQUID VERSUS SNOW OUTCOME ALONG A KMCW-KISW LINE...WITH SNOW NORTHWEST. OVERALL...DID RAISE PRECIPITATION CHANCES BUT OVERALL CHANGES WERE MINOR WITH THAT SYSTEM. THE LONGWAVE TROUGH DIGS DEEPLY INTO MEXICO ON THE WEEKEND AND THERE IS HIGH SPREAD ON THE OUTCOMES FOR THIS MAJOR ENERGY. THERE WILL BE MAJOR WINTER WEATHER WITH THIS SYSTEM...BUT THE FURTHER SOUTH IT DIGS...THE MORE THE AREA WOULD SEEM TO REMAIN UNDER THE NRN STREAM OF ENERGY AND NOT BE AFFECTED. HAVE SMALL CHANCES OF PRECIPITATION IN THE FORECAST FOR NOW MAINLY FOR E/SE AREAS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 602 AM CST MON DEC 16 2013 A COUPLE OF WEAK DISTURBANCES WILL BRING TWO ROUNDS LIGHT SNOW TO THE TAF SITES WITH IFR CONDITIONS EXPECTED. THE FIRST ROUND WILL MOVE INTO KRST AROUND 14Z...THEN INTO KLSE AROUND 15Z...WITH VISIBILITIES FALLING TO 1.5 MILES AND CEILINGS LOWERING INTO THE 800 TO 1KFT RANGE. THIS FIRST ROUND OF SNOW SHOULD EXIT THE AREA BY LATE THIS AFTERNOON WITH CONDITIONS IMPROVING TO VFR. THE SECOND ROUND OF LIGHT SNOW MOVES IN AFTER MIDNIGHT TONIGHT WITH IFR CONDITIONS EXPECTED ONCE AGAIN. PLAN ON TOTAL SNOW ACCUMULATIONS OF AROUND 1 INCH AT KRST AND AROUND 2 INCHES AT KLSE. THE SECOND ROUND OF SNOW WILL TAPER OFF AFTER 12Z WITH VFR CONDITIONS RETURNING. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BAUMGARDT LONG TERM...BAUMGARDT AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
329 AM CST MON DEC 16 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 329 AM CST MON DEC 16 2013 MONITORING DYNAMIC SYSTEM NEAR LAKE WINNIPEG AND THE RADAR BAND DEVELOPING ACROSS ND AT 08Z. OTHER RADAR ECHO AND SOME SCT REPORTS OF SN- BEING REPORTED ALONG WARM ADVECTION ARM EXTENDING THROUGH THE EASTERN DAKOTAS AND INTO THE MN RIVER VALLEY. THIS SYSTEM WAS HANDLED WELL AND FEW CHANGES WERE MADE TO THE ONGOING FORECAST FOR TODAY EXCEPT FOR TIMING. STRONG CIRCULATION CLEARLY SEEN IN GOES WATER VAPOR IMAGERY NEAR LAKE WINNIPEG AND THIS SYSTEM AND ITS POTENTIAL VORTICITY ADVECTION WILL DIG TOWARD LAKE SUPERIOR AND DRAG GOOD DYNAMICS ACROSS NORTHERN WI TODAY. THIS POTENTIAL VORTICITY ADVECTION...IN COMBINATION WITH WARM ADVECTION ALONG THE THERMAL RIBBON FROM 700-900 MB...AND SOME MODERATE 250MB JET EXIT REGION DIVERGENCE WILL PRODUCE A SWATH OF 1-2 SNOW TODAY. HRRR TRENDS SHOW A SOMEWHAT NARROW BAND SHIFTING ACROSS WI DURING THE DAY...WITH ABOUT 2 HOURS OF SNOW AT ANY ONE POINT. HI-RES WINDOWS FROM NCEP NMM/ARW 16.00Z RUNS SUGGEST SIMILAR TIMING TODAY AND INTENSITY...BUT MAYBEA BIT WIDER BAND. A BREAK OCCURS LATE TODAY AND THIS EVENING...BUT HAVE INCREASED THE SNOW CHANCES TONIGHT WITH ANOTHER 1-2 INCHES NOW EXPECTED ALONG AND NORTH OF I-90. SECONDARY SHORTWAVE TROUGH RIDING ON THE NOSE OF THE POLAR JET WILL COME ACROSS THE AREA TONIGHT...A DIRECT HIT. SO...SNOWFALL SHOULD BREAK OUT AGAIN ALONG AND NORTH OF I-90 AROUND MIDNIGHT...WITH AREAS SOUTH A BIT MORE LIMITED IN THEIR SATURATION. THE ENERGY WILL SHIFT EAST BY SUNRISE. MODEL GUIDANCE HAS SOME SPREAD ON THE LOCATION OF THE SNOW WITH SOME SOLUTIONS FURTHER SOUTH...BUT IT SEEMS THE TRACK OF THE WAVE AND THE JET FLOW ALOFT WOULD SHOW PREFERENCE TO THE I-90 CORRIDOR AND NORTH. NEW SNOW TOTALS BY TUESDAY MORNING WILL BE IN THE 1-3 INCH RANGE WITH THE 3 INCH TOTALS MOST LIKELY ALONG AND NORTH OF I-94. HAVE COLLABORATED WITH SURROUNDING NWS OFFICES AND WILL HOLD OFF ON THE ADVISORY AS THE TWO SYSTEMS SHOULD BE SPACED IN TIME...AND THE 3 INCH TOTALS SHOULD BE THE HIGHER END RATHER THAN THE RULE. WILL COVER IT IN THE HAZ WEATHER OUTLOOK AND POSSIBLY A SPECIAL STATEMENT. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 329 AM CST MON DEC 16 2013 TUESDAY LOOKS TO BE A BREEZY DAY BEHIND THIS WAVE...IN THE 15-25 MPH RANGE. THEN...RIDGE BUILDING STARTS WITH MAINLY SUNSHINE EXCEPT ACROSS THE NORTH WHERE THE STORM TRACK SHIFT TO. A STRONG SHORTWAVE TRAVELS ALONG THE U.S. CANADA BORDER AND MORE WARM ADVECTION IS EXPECTED TUESDAY NIGHT AND WEDNESDAY NIGHT...WITH PRECIPITATION STILL OFF TO THE NORTH. THURSDAY-SUNDAY... SIGNALS CONTINUE IN THE MODEL GUIDANCE FOR PRECIPITATION TO SPREAD IN LATE THURSDAY AND THURSDAY NIGHT WITH THE FIRST SHORTWAVE TROUGH EJECTION FROM THE LONGWAVE DEVELOPING ACROSS THE WRN CONUS. THE SIGNAL IS REMAINING CONSISTENT WITH THE GFS AND GFS ENSEMBLES STILL THE COLDER SOLUTIONS...WITH THE FRONTAL BOUNDARY REMAINING THROUGH IL AND THE SOUTHERN FORECAST AREA IN SUB-ZERO SURFACE TEMPERATURES. ACROSS ABOUT THE SOUTHERN TWO-THIRDS...THE LIFT APPEARS LIMITED WITH ABUNDANT MOISTURE IN THE 0-3KM LAYER...BUT NOT ABOVE IN THE ICE PRODUCING LAYER. THUS THE GFS HAS A 3KM DEEP SUPERCOOLED LIQUID LAYER...CONSISTENT OVER THE PAST RUNS. THIS IS A FZDZ/FZRA SITUATION AND HOLD THE POTENTIAL FOR ICING. THE WARMER SOLUTIONS OF THE ECMWF/CANADIAN MODELS WOULD CAUSE RAIN IN THE SOUTH. THE SPREAD IN THE TEMPERATURE PROFILE IS STILL VERY LARGE THURSDAY/THU NIGHT AMONG THE WARM VERSUS COLD SOLUTIONS...WITH SURFACE HIGHS 28F IN THE GFS THURSDAY...AND 45F IN THE CANADIAN MODEL...WITH THE 16.00Z ECMWF IN THE MIDDLE. THAT IS WHERE OUR FORECAST TEMPERATURES REMAIN...THUS A MORE LIMITED ICING AREA IN NERN IA AND SWRN WI...AND AMOUNTS HAVE TRENDED LOWER...LESS THAN 0.10 INCHES. TO THE NORTH ON THURSDAY NIGHT IT APPEARS THE NORTHERN STREAM WAVE WILL PROVIDE ENOUGH FORCING FOR DEEP SATURATION AND LIGHT SNOWFALL THAT WOULD ACCUMULATE AROUND AN INCH. CURRENT FORECAST HAS THIS LIQUID VERSUS SNOW OUTCOME ALONG A KMCW-KISW LINE...WITH SNOW NORTHWEST. OVERALL...DID RAISE PRECIPITATION CHANCES BUT OVERALL CHANGES WERE MINOR WITH THAT SYSTEM. THE LONGWAVE TROUGH DIGS DEEPLY INTO MEXICO ON THE WEEKEND AND THERE IS HIGH SPREAD ON THE OUTCOMES FOR THIS MAJOR ENERGY. THERE WILL BE MAJOR WINTER WEATHER WITH THIS SYSTEM...BUT THE FURTHER SOUTH IT DIGS...THE MORE THE AREA WOULD SEEM TO REMAIN UNDER THE NRN STREAM OF ENERGY AND NOT BE AFFECTED. HAVE SMALL CHANCES OF PRECIPITATION IN THE FORECAST FOR NOW MAINLY FOR E/SE AREAS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1115 PM CST SUN DEC 15 2013 THE BAND OF LIGHT SNOW THIS EVENING HAS PERSISTED LONGER AND MOVED A LITTLE FARTHER NORTHEAST THAN PREVIOUSLY EXPECTED. HOWEVER...IT CONTINUES TO MOVE SOUTHEAST AND WILL BE PAST BOTH TAF SITES BY 06Z. LOOKING UPSTREAM BEHIND THE SNOW BAND...VFR CONDITIONS EXPECTED TO PREVAIL THROUGH THE NIGHT. THE NEXT SHORT WAVE TROUGH CONTINUES TO MOVE SOUTHEAST ACROSS SASKATCHEWAN AND WILL MOVE ACROSS THE UPPER MIDWEST MONDAY. GOOD FORCING FROM THIS WAVE EXPECTED TO PRODUCE ANOTHER BAND OF LIGHT SNOW DURING THE DAY. THE 15.21Z SREF CONTINUES TO INDICATE IFR CONDITIONS IN THE LIGHT SNOW AND WILL SHOW THIS AT BOTH TAF SITES FROM MID MORNING INTO THE EARLY AFTERNOON. THE 16.00Z NAM CONTINUES TO SUGGEST THE POSSIBILITY OF LOOSING ICE IN THE CLOUDS AS THE PRECIPITATION IS COMING TO AN END FOR THE POSSIBILITY OF SOME FREEZING DRIZZLE. CONFIDENCE IS NOT HIGH IN THIS OUTCOME AND OPTED TO NOT INCLUDE AT THIS TIME. CONDITIONS SHOULD GO BACK UP TO VFR BEHIND THE SNOW BAND ONLY TO COME BACK DOWN TO MVFR DURING THE LATE EVENING AS THE NEXT SHORT WAVE TROUGH APPROACHES. THIS WAVE WILL PRODUCE YET ANOTHER BAND OF LIGHT SNOW OVERNIGHT MONDAY AND THE NEXT FORECAST WILL HAVE TO ADDRESS THIS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BAUMGARDT LONG TERM...BAUMGARDT AVIATION...04
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1157 PM CST TUE DEC 17 2013 .DISCUSSION... 845 PM CST FOR EVENING UPDATE... MINOR TWEAKS TO NEAR TERM GOING FORECAST THIS EVENING...MAINLY TO RAISE MIN TEMPS A LITTLE OVERNIGHT AND TO TWEAK SKY COVER THIS EVENING BASED ON SATELLITE TRENDS. HIGHLY SHEARED MID-LEVEL SHORT WAVE NOTED IN FAST NORTHWEST FLOW ALOFT PER RAOB/GOES VAPOR IMAGERY ACROSS THE AREA EARLY THIS EVENING...WITH 85-95 KT H5 SPEED MAX NOTED IN MPX-DVN-ILX RAOBS. REGIONAL RADAR MOSAIC HAS BEEN DEPICTING AN AREA OF VERY LIGHT SNOW AND FLURRIES ACROSS SOUTHERN WI AND FAR NORTHEAST IL THIS EVENING IN ASSOCIATION WITH THIS FEATURE...WITH AN AREA OF BKN-OVC CLOUD COVER AS FAR SOUTH AS THE STREATOR-KANKAKEE-REMINGTON AREAS. MODEL GUIDANCE PICKS UP ON THIS SHEARED WAVE...MOVING IT QUICKLY EAST OF THE AREA BY/AFTER 06Z. THIS SHOULD ALLOW CLEARING FROM THE WEST DURING THE LATE EVENING/OVERNIGHT HOURS...WITH BACK EDGE OF LOWER CLOUDS NOW ROUGHLY MONROE WI-PERU IL. SOME PATCHY CIRRUS WILL CONTINUE TO SPILL IN FROM THE NORTHWEST IN ASSOCIATION WITH UPPER JET. BRISK WEST-NORTHWEST WINDS WILL DECREASE AFTER MIDNIGHT... AS SURFACE RIDGE AXIS NOW OVER IA-MN BUILDS EAST IN RESPONSE TO RISING HEIGHTS ALOFT IN WAKE OF DEPARTING UPPER TROUGH. DESPITE LIGHTER WINDS...CLEARING SKIES AND SNOW COVER...WARM ADVECTION IS ALREADY DEVELOPING ALOFT WEST OF THE MISSISSIPPI RIVER AS WINDS BACK TO THE WEST-SOUTHWEST WITH APPROACHING WARM FRONT. SURFACE DEW POINTS HOLDING IN THE LOW-MID TEENS ACROSS THE REGION AND THOUGH THEY WILL LIKELY DROP A LITTLE BIT...HAVE BUMPED UP FORECAST MINS 1-2 DEG ACROSS THE CWA TO NEAR 10 (WITH ARR/RPJ STILL IN UPPER SINGLE DIGITS) ACROSS NORTH CENTRAL IL...AND TEENS MAINLY ELSEWHERE. OTHERWISE...ONLY CHANGE WAS TO INCREASE CLOUD COVER PERCENTAGE IN SKY GRIDS A BIT WITH THE AFOREMENTIONED PATCH OF BKN-OVC CLOUDS CURRENTLY OVER THE CWA. REMAINDER OF FORECAST APPEARS IN GOOD SHAPE THROUGH TOMORROW. RATZER //PREV DISCUSSION... 327 PM CST A VERY ACTIVE WEATHER PATTERN IS EXPECTED THROUGH THE WEEKEND WITH A PLETHORA OF CONCERNS...INCLUDING PRECIP TIMING...TYPES AND AMOUNTS...ESPECIALLY WITH THE WEEKEND SYSTEM. AFTER ANOTHER CHILLY NIGHT TONIGHT UNDER PARTLY CLOUDY SKIES...SOUTHWESTERLY WINDS WILL PICK UP...PRODUCING A WARMER DAY ACROSS THE REGION FOR WEDNESDAY. IT APPEARS THAT TEMPERATURES WILL CLIMB AT LEAST A COUPLE OF DEGREES ABOVE FREEZE ACROSS THE WHOLE AREA. UNFORTUNATELY...THE EXTENSIVE SNOW PACK WILL KEEP TEMPERATURES FOR WARMING MORE...AT LEAST UNTIL THURSDAY. THE GUIDANCE IS HAVING TROUBLE WITH AGREEING ON THE PLACEMENT OF A FRONTAL ZONE ON THURSDAY. THE NCEP MODELS...NAMELY THE GFS AND NAM SUGGEST THAT THIS BOUNDARY WILL SAG SOUTHWARD TO NEAR THE I-80 CORRIDOR DURING THE DAY ON THURSDAY. THIS SOLUTION WOULD FAVOR COOLER TEMPERATURES NEAR FREEZING ACROSS FAR NORTHERN ILLINOIS ON THURSDAYS. HOWEVER...THE ECMWF SUGGESTS THAT THIS FRONT WILL REMAIN ACROSS FAR SOUTHERN WISCONSIN...WITH SOUTHERLY FLOW AND WARMER CONDITIONS CONTINUING. I HAVE CHOSEN TO FOLLOW CLOSER TO THE ECMWF AS IT APPEARS THAT THE SURFACE LOW...WHICH THE FRONTAL ZONE EMANATES FROM...ACROSS THE UPPER GREAT LAKES REGION IS BEING OVERDONE A BIT BY THE NCEP MODELS...AND AS A CONSEQUENCE THEY DRIVE THE FRONT A BIT FARTHER SOUTH ACROSS NORTHERN ILLINOIS. OVERALL...THE ECMWF WOULD SUGGEST MUCH LESS OF A THREAT OF FREEZING DZ/RAIN AND LIKELY KEEP IT LIQUID WITH SURFACE TEMPS ABOVE FREEZING. THE ONLY EXCEPTION TO THIS MAY BE ACROSS FAR NORTHERN ILLINOIS. OVERALL...THE INCREASE IN LOW LEVEL MOISTURE TO THE SOUTH OF THE FRONTAL ZONE WILL LIKELY LEAD TO LOW CLOUDS AND EVEN FOG ACROSS MUCH OF THE AREA LATER THURSDAY INTO THURSDAY NIGHT. A SURFACE WAVE IS FORECAST TO MOVE ALONG THE FRONTAL ZONE THURSDAY NIGHT INTO FRIDAY...AND THIS FINALLY ALLOW THE FRONT TO SHIFT SOUTHWARD ACROSS THE AREA BY FRIDAY. IT APPEARS ISENTROPIC ASCENT WILL PRODUCE SOME LIGHT PRECIP IN ASSOCIATION WITH THIS SURFACE WAVE THURSDAY NIGHT INTO FRIDAY. AS THE COLD AIR BEGINS TO FILTER SOUTHWARD IT APPEARS THE PRECIP COULD EITHER CHANGE OVER TO A PERIOD OF LIGHT SNOW...OR FREEZING DRIZZLE. SOME OF THE FORECAST SOUNDINGS INDICATE THAT THE DENDRITIC GROWTH ZONE WILL BE VOID OF DECENT MOISTURE...WHICH WOULD FAVOR FREEZING DRIZZLE OVER LIGHT SNOW. I HAVE MENTIONED A SNOW OR LIGHT FREEZING DRIZZLE CHANCE OVER NORTHERN ILLINOIS LATE THURSDAY NIGHT INTO FRIDAY MORNING TO COVER THIS POTENTIAL. OTHERWISE ATTENTION TURNS TO THE SYSTEM EXPECTED TO DIG ACROSS THE SOUTHWEST..NEAR BAJA CALIFORNIA BY FRIDAY NIGHT. THIS DIGGING SYSTEM IS EXPECTED TO TRANSITION A QUASI-ZONAL FLOW PATTERN ACROSS THE CONUS INTO A SOUTHWESTERLY FLOW PATTERN ALOFT...AS DOWNSTREAM HEIGHT RISES LEAD TO POSITIVE HEIGHT ANOMALIES AND RIDGING ACROSS THE EASTERN CONUS. THIS PATTERN IS VERY CONDUCIVE TO PRODUCING A SIGNIFICANT PRECIP EVENT ACROSS PORTIONS OF THE CENTRAL CONUS. A STRONG AND IMPRESSIVE SOUTHERLY 60+ KT LOW LEVEL JET IS PROGGED TO DEVELOP BY SATURDAY IN RESPONSE TO THE PATTERN SHIFT...WITH LOW PRESSURE DEVELOPING ACROSS TEXAS. THIS LOW LEVEL JET WILL TRANSPORT COPIOUS AMOUNTS OF MOISTURE NORTHWARD ACROSS THE MISSISSIPPI AND OHIO VALLEYS. OVERALL...THIS CONTINUES TO BE A VERY COMPLEX FORECAST AS THE SYSTEM APPEARS THAT IT WILL...AT LEAST TEMPORALLY...SEPARATE ITSELF FROM THE MAIN SOUTHERN STREAM FLOW. MUCH OF THE GUIDANCE IS IN FAIR AGREEMENT WITH TAKING THIS SYSTEM EAST-NORTHEASTWARD ACROSS THE TEXAS PANHANDLE LATE SATURDAY AND THEN MERGING BACK INTO THE MAIN TROUGH BY SUNDAY AS IT MOVES ACROSS MISSOURI. OVERALL...IN THE LOWER LEVELS...THIS LOOKS TO SET UP A FRONTAL BOUNDARY RIGHT ACROSS THE CENTRAL STATES...WITH AN ELONGATED AREA OF SURFACE LOW PRESSURE LIKELY TO TRANSITION ALONG THE BOUNDARY THROUGH THE WEEKEND. STRONG MOISTURE CONVERGENCE AND FRONTOGENESIS IS LIKELY IN THE VICINITY OF THE SOUTHWEST TO NORTHEAST ORIENTED BOUNDARY...ALONG THE NOSE OF THE LOW LEVEL JET. THIS WILL LIKELY RESULT IN HEAVY PRECIPITATION ACROSS AT LEAST PORTIONS OF THE AREA LATE SATURDAY INTO SUNDAY. THE MAIN QUESTIONS AT THIS POINT CONTINUE TO BE...WHAT FORM WILL THE PRECIP BE? I CONTINUE TO FOLLOWER CLOSER TO THE ECMWF SOLUTION FOR THE SYSTEM AS IT HAS BEEN VERY GOOD LATELY. THE MAIN CONCERNS I HAVE IS THE THERMAL PROFILE WITH THIS SYSTEM. IT IS POSSIBLE THAT THE PRECIP BEGINS AS A WINTER MIX OF RAIN FREEZING RAIN SLEET AND SNOW...ESPECIALLY ACROSS THE NORTH. MY SOUTHERN COUNTIES MAY BECOME WARM ENOUGH TO RESULT IN MAINLY RAIN...AT LEAST THROUGH SATURDAY NIGHT. THERE ARE DEFINITELY SIGNS THAT THIS SYSTEM COULD TRANSITION OVER TO FREEZING RAIN AND THEN SNOW SATURDAY NIGHT ACROSS NORTHERN ILLINOIS AS THE SYSTEM TRYS TO PULL IN COLDER AIR IN THE LOWER LEVELS FOR THE NORTH. SIGNIFICANT ACCUMULATIONS ARE CERTAINLY POSSIBLE ACROSS PORTIONS OF NORTHERN ILLINOIS. HOWEVER...THE THERM PROFILE...AND HENCE WHERE SNOW VERSE RAIN WILL FALL COULD EASILY CHANGE IN FUTURE FORECASTS. SO...IN SPITE OF THE FACT CONFIDENCE IS INCREASING THAT WE WILL SEE A DECENT PRECIP EVENT ACROSS THE AREA. CONFIDENCE ON PRECIP TYPE...AND WHERE THE RAIN/VERSES HEAVY SNOW LINE SETS UP REMAINS LOW AT THIS TIME. FOR THESE REASONS...IT IS TOO EARLY TO START MENTIONING AMOUNTS OF SNOW OR ICE FOR ANY GIVEN AREAS. THE AMOUNT OF PRECIP WITH THIS SYSTEM COULD CAUSE HYDRO ISSUES...WITH PRECIP AMOUNTS POSSIBLY EXCEEDING AN INCH OR TWO ACROSS PORTIONS OF THE AREA. THIS WILL HAVE TO BE WATCHED...ESPECIALLY IF THE PRECIP FALLS AS RAIN ON TOP OF ANY REMAINING SNOW PACK. ANOTHER SHOT OF COLDER AIR WILL OVERSPREAD THE AREA EARLY NEXT WEEK IN THE WAKE OF THIS SYSTEM...WITH HIGH PRESSURE BUILDING IN ACROSS THE REGION. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * GUSTY SOUTH WINDS DEVELOP THIS AFTN WITH MAX GUSTS BTWN 20 AND 25 KT. * MVFR TO PSBL IFR CIGS AND MVFR FOG DEVELOP THIS EVENING. * COULD SEE -DZ OR -FZDZ EARLY THURSDAY MORNING. JEE //DISCUSSION...UPDATED 06Z... A RIDGE OF HIGH PRESSURE IS APPROACHING FROM THE WEST WITH VFR CIGS THINNING OUT OVER THE NEXT HOUR OR SO. WINDS WILL SLOWLY BECOME SOUTH BY THIS AFTERNOON AND BEGIN GUSTING TO 20 TO 25 KT. A TROUGH OF LOW PRESSURE THEN MOVES IN FROM THE WEST TOMORROW EVENING. THE UPPER LEVEL PRESSURE GRADIENT REMAINS STRONG SO OCNL GUSTS TO ARND 20 KT ARE POSSIBLE OVERNIGHT. WINDS WILL ALSO BECOME MORE SSW OVERNIGHT. WARM AIR AND MOISTURE WILL BE ADVECTED INTO THE REGION RESULTING IN CIGS LOWERING AND FOG DEVELOPMENT. FIRST...THE WARM AIR WILL INTERACT WITH THE SNOW PACK CREATING FOG. NOT SURE HOW DENSE THE FOG WILL BE AT THIS POINT...SO KEPT MVFR VSBYS GOING. THINKING ORD AND MDW WILL REMAIN OUT OF THE DENSER FOG AS THE TYPICALLY DO...BUT THE REMAINING TERMINALS WILL LIKELY SEE DENSER FOG THEN FORECAST. NOT SURE HOW DENSE AT THIS TIME. NOW FOR CIGS...GUIDANCE INDICATES MVFR IF NOT IFR CIGS ARE LIKELY TOMORROW EVENING AND OVERNIGHT. WILL REFINE THE CIG HEIGHTS AS CONFIDENCE GROWS. SOUNDINGS ALSO TRY TO SUGGEST THE ADDED MOISTURE MAY PRODUCE DRIZZLE OR FREEZING DRIZZLE...BUT NOT SURE HOW MUCH OF THAT MOISTURE WILL BE FOG VS. PRECIP. THEREFORE LEFT THE TAFS DRY FOR NOW. ALSO NOTE DRIZZLE VS. FREEZING DRIZZLE WILL DEPEND ON TEMPS...AND RIGHT NOW TEMPS LOOK LIKE THEY WILL BE RIGHT AROUND FREEZING. JEE //ORD AND MDW CONFIDENCE...UPDATED 06Z... * HIGH CONFIDENCE IN TAFS THROUGH 00Z. * MEDIUM CONFIDENCE IN GUSTS PERSISTING OVERNIGHT...GUSTS MAY BE LESS FREQUENT THAN FORECAST. * HIGH CONFIDENCE IN AT LEAST MVFR CIGS THIS EVENING...LOW CONFIDENCE IN HOW LOW CIGS WILL FALL. IFR OR LOWER IS PSBL. * HIGH CONFIDENCE IN FOG THIS EVENING...LOW CONFIDENCE IN HOW THICK FOG WILL BE AND TIMING. * LOW CONFIDENCE IN -DZ OR -FZDZ OCCURRING AND TIMING EARLY THURSDAY MORNING. JEE //OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z... THURSDAY...IFR/LIFR LIKELY. CHANCE OF -RA/DZ WITH AREAS OF FOG. FRIDAY...IFR LIKELY. CHANCE OF -RA/-SN. SATURDAY...IFR POSSIBLE. CHANCE OF WINTRY MIX DURING THE DAY...THEN SNOW AT NIGHT. SUNDAY...IFR POSSIBLE. SNOW LIKELY. MONDAY...MVFR CEILINGS POSSIBLE. RODRIGUEZ && .MARINE... 315 PM CST WILL LEAVE HEADLINES AS IS THIS EVENING FOR MARGINAL WESTERLY GALES ON SOUTHERN PART OF THE LAKE...BUT ALLOW EVENING SHIFT TO ASSESS AND POSSIBLY CANCEL EARLY. SMALL CRAFT ADVISORY FROM WINTHROP HARBOR TO GARY IS IN GOOD SHAPE. THEN CONCERN SHIFTS TO LIKELY SOUTH-SOUTHWEST GALES ON WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT COURTESY OF STRONG PRESSURE FALLS AND A TIGHT PRESSURE GRADIENT WITH LOW PRESSURE APPROACHING FROM THE WEST AND HIGH PRESSURE OVER THE OH VALLEY. HAVE HIGHEST CONFIDENCE IN GALES DEVELOPING ON THE SOUTH HALF WITH SOMEWHAT LESSER CONFIDENCE ON THE NORTH IN TERMS OF DURATION AND SEEING PREVAILING GALES...BUT FELT IT WAS PRUDENT TO ISSUE A GALE WATCH FOR THE ENTIRE OPEN LAKE FROM 21Z WEDS TO 10Z THURS. WILL LIKELY NEED A SCA FOR THE NEAR SHORE ZONES DURING THIS TIME. AFTER GALE IS DROPPED FOR GARY TO MI CITY NSH ZONE THIS EVENING...ITS POSSIBLE THAT THE SCA MAY JUST BE EXTENDED THROUGH TOMORROW NIGHT FOR THIS ZONE. A COLD FRONT WILL THEN SHIFT SOUTH DOWN THE LAKE THURSDAY THROUGH THURSDAY NIGHT..WITH LARGE VARIANCE AMONGST FORECAST GUIDANCE IN THE TIMING OF THIS FRONT. HAVE FAVORED A SLOWER MOVEMENT OF THE FRONT DOWN THE SOUTHERN PORTION OF THE LAKE WITH THIS FORECAST ISSUANCE. THERE IS SOME POTENTIAL FOR FAIRLY STRONG BUT LIKELY SUB-GALE NORTHERLY WINDS BEHIND THE FRONT. WEAK HIGH PRESSURE WILL THEN RESULT IN LIGHTER WINDS FRIDAY NIGHT INTO SATURDAY. HOWEVER...ANOTHER STRONGER SYSTEM THEN LOOKS TO MOVE FROM THE OHIO VALLEY TOWARD THE CENTRAL LAKES LATE SATURDAY INTO SUNDAY. THE POTENTIAL CERTAINLY EXISTS FOR NORTHEAST TO NORTH GALES IN ASSOCIATION WITH THIS SYSTEM DEPENDING ON ITS ULTIMATE TRACK AND STRENGTH...BUT FOR NOW HAVE INCREASED WINDS TO 30 KT. RC && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 10 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL MIDNIGHT WEDNESDAY. GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...3 PM WEDNESDAY TO 4 AM THURSDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
  [top] Area Forecast Discussion National Weather Service Lincoln IL 1111 PM CST Tue Dec 17 2013 .DISCUSSION... ISSUED 815 PM CST Tue Dec 17 2013 Surface high pressure over eastern Kansas and western Missouri early this evening will track to our south tonight. A very dry air mass was advecting southeast into central Illinois this evening with mid to upper teens common over the northern half of the forecast area. The dry air combined with just enough wind overnight should keep any significant fog problems at bay. Last few runs of the HRRR model have backed off with the low vsbys in parts of our area but with the ridge axis expected to be right over our area by 12z, not that confident to remove the current patchy fog wording in the grids late tonight. As the surface high shifts off to our southeast tomorrow, we can expect an increasing southerly wind across the entire area which should help push temperatures into the upper 30s north to the middle 40s southwest. Have made some minor adjustments to the evening dew points and temperatures, as well as backing off the fog wording until the 4am to 8am time frame. Updated zones should be out soon. && .AVIATION... ISSUED 1110 PM CST Tue Dec 17 2013 Except for the potential for a brief period of fog in the 10z-14z time frame...VFR conditions are expected to prevail. Another issue to address will be the threat for low level wind shear tomorrow night as the surface winds decouple while winds around 1500 feet remain out of the southwest at 40-50 kts. Surface winds tonight will continue from a westerly direction but continue to slowly decrease as the night wears on with the surface ridge axis passing thru central IL around dawn. Then, winds will back into a southwest to south direction Wednesday morning and increase to between 12 and 17 kts by early afternoon, with a few gusts up to 22 kts thru the mid afternoon hours before diminishing to around 12 kts after dark. With surface temperatures expected above freezing in all areas tomorrow, there should be quite a bit of melting of the snow, which in turn may bring about an increasing chance for the development of fog and low clouds late Wednesday night. However, it appears southerly winds will hold up enough to keep it out of the forecast thru 06z Thu. Smith && .PREV DISCUSSION... ISSUED 300 PM CST Tue Dec 17 2013 The short term will be highlighted by a warming trend through mid week. Fog may become an issue as the snow melts over the next few days. A cold front is still slated for Friday morning, with a major winter storm taking aim on the area for the weekend. Precip type issues remain the biggest challenge with that storm. The 12z guidance has generally trended warmer on Sat and Sat night, which means rain longer and farther north, with a band of freezing rain in our northern area. Snow chances may hold off until very late Sat night and possibly until Sunday as the colder air finally flows into central IL. Snow amounts on the NW side of this system could be very high, with the latest trends putting that band just to our northwest. Any shift in the placement of the stationary front and track of the low up along the front will be critical to precip type distribution and amounts of snow and ice. SHORT TERM...Tonight through Friday night. The quick clipper snows from today should be out of our southeast counties by evening. We will not mention any snow in the worded zones as a result. Fog potential tonight does not appear as high as previous model runs, although the models have not been handling the ground level moisture very well at all. We kept a mention of patchy fog in our grids for tonight, but do not expect any widespread dense fog despite very light winds and clear skies. Wednesday will see high pressure sliding east of IL and southerly winds increasing. Warm advection flows will intensify in the afternoon, helping to push temperatures into the 40s in many areas. Snow cover will reduce the effective heating of the sun, with energy going to melting the snow. That may keep highs in the upper 30s over areas with deeper snow. The additional ground level moisture should help fog develop Wed night, despite some steadier south winds overnight. Fog should linger Thursday morning as mid and upper level moisture increases ahead of the approaching cold front. Rain showers should hold off until afternoon when isentropic lift intensifies due to 45kts of flow up the 295k surface. Rain should generally remain north of Lincoln in proximity to the developing mid-level warm front and nose of the theta-e ridge. There remains some concern as to the extent of freezing rain later Thursday night into Friday morning as surface temps northwest of Peoria dip below freezing behind the cold front. We kept a mention of FZRA in that area, with a thin layer of icing possible. Precipitation chances should become confined mainly to the southeast half of our area Friday afternoon and Friday night as the cold front and shortwave shift east. Once again, any rain falling into the night could transition to freezing rain along and north of I-72. The cold front is projected to stall out just to the southeast of Illinois, in prep for a return push northward when the weekend storm approaches. LONG TERM...Saturday through Tuesday. A surge of warm air and moisture in the mid levels will strengthen on Saturday, pushing the front back north as a warm front. Rain will re-develop or advance northward during the day, with freezing rain possible in the morning north of I-72 before surface temps climb above freezing. All or our forecast area except maybe around Galesburg should climb above freezing during the afternoon, keeping all precipitation as rain. The timing and speed of the low riding up the front will dictate how soon that colder air will be drawn into the northern edges of the storm and change the rain to freezing rain and eventually snow. Saturday night could see an extended period of freezing rain in a band from SW to NE across our counties, including areas from Rushville/Jacksonville/ Springfield north to Canton/Peoria and east to Bloomington and Champaign. Ice amounts could reach over a quarter inch in some areas, depending on how soon the cold air arrives at low levels. Snow is expected to develop on the NW fringes of our area as soon as Saturday evening, but more likely after midnight into Sunday. A couple of inches of snow could accumulate on Sunday in areas west of I-57, with lesser amounts toward I-57 and east. A band of deformation snows could increase those amounts in bands west of I-55. There remains a great deal of uncertainty with the weekend storm system, but the trends have been for a warmer solution in our counties, even from the previously colder ECMWF. Dry and colder conditions will follow the storm, and should set up better travel conditions for Christmas Eve day through Christmas, and possibly longer. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
144 AM EST WED DEC 18 2013 .UPDATE... ISSUED AT 135 AM EST WED DEC 18 2013 HOURLY GRIDS WERE FRESHENED UP FOR RECENT TRENDS IN HOURLY TEMPS...DEWPOINTS AND WINDS. BREAKS WORKING ACROSS THE AREA FROM THE WEST AND HOLES IN THE LOW CLOUDS WILL LEAD TO VALLEY TEMPS...EVEN IN THE EAST THAT HAVE LEVELED OFF DROPPING AGAIN TOWARD DAWN. UPDATE ISSUED AT 1025 PM EST TUE DEC 17 2013 DID A QUICK UPDATE TO ADD SOME LOW CLOUDS INTO THE NORTHERN PARTS OF THE CWA AS THAT LAST WAVE PASSES BY TO THE NORTHEAST OVERNIGHT. DID ALSO UPDATE THE AVIATION GRIDS TO REFLECT THESE MVFR CIGS. FINE TUNED OVERNIGHT LOWS IN LIGHT OF THE COLD TO NEUTRAL ADVECTION OVERNIGHT AND NORTHERN CLOUDS. THESE UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. UPDATE ISSUED AT 650 PM EST TUE DEC 17 2013 23Z SFC ANALYSIS SHOWS A DEPARTING AREA OF LOW PRESSURE...WITH A TIGHT AND COMPACT PRESSURE GRADIENT...EXITING KENTUCKY. THIS IS TAKING A BATCH OF LIGHT RAIN...AND SNOW ON THE NORTHERN FRINGE... EAST AND OUT OF THE AREA...AS WELL. THE LATEST HIGH RESOLUTION MODELS SUPPORT THIS TREND WITH THE HRRR AND RUC13 ESSENTIALLY DRY THROUGH THE REST OF THE NIGHT. HIGH PRESSURE BUILDING INTO EAST KENTUCKY WILL CLEAR MOST OF THE CLOUDS OUT OF THE SKY LEAVING BEHIND JUST A SMATTERING OF MID LEVELS ONES THAT COULD PRODUCE A FEW FLURRIES THROUGH THE REST OF THE EVENING. OTHERWISE...IT WILL BE DRIER AND COLDER OVERNIGHT WITH TEMPERATURES FALLING INTO THE MID 20S BY EARLY WEDNESDAY MORNING. HAVE UPDATED THE GRIDS TO REFLECT THIS MAKING CHANGES PRIMARILY TO THE POPS AND WX ONES AND T/TD TO A LESSER EXTENT. THESE HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. UPDATES TO THE ZFP AND HWO WILL BE ISSUED SHORTLY...ONCE THE MEASURABLE PCPN CLEARS THE CWA WITHIN THE HOUR. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT) ISSUED AT 331 PM EST TUE DEC 17 2013 MODELS HAVE BEEN CHANGING THROUGHOUT THE LAST 24 HOURS...MAKING IT HARD TO PINPOINT AN EXACT FORECAST UNTIL LOOKING AT ONGOING CONDITIONS. SO FAR TODAY...THE HRRR SEEMS TO BE INITIALIZING THE BEST WITH ONGOING CONDITIONS...AND THE OTHER HIRES MODELS HAVE FOLLOWED SUIT THROUGHOUT THE DAY. BASED ON CURRENT TRENDS...AND LATEST HIRES MODEL DATA...FAVOR A LESS IMPACTFUL EVENING WITH MAINLY LIGHT RAIN...ENDING BEFORE MIDNIGHT IN MOST AREAS. WITH TEMPERATURES WELL ABOVE FREEZING IN MOST LOCATIONS RIGHT NOW...AND ROAD TEMPS SITTING ABOVE FREEZING AS WELL...DO NOT EXPECT ANY IMPACTS OTHER THAN SOME LIGHT RAIN...MAINLY NORTH OF THE MOUNTAIN PARKWAY. CLOUD COVER CURRENTLY EXTENDS SOUTHWARD ACROSS MUCH OF THE CWA. AS PRECIPITATION QUICKLY MOVES OFF TO THE EAST...TEMPERATURES WILL COOL WITH LOSS OF DAYTIME HEATING...BUT LATEST DATA SUPPORTS THE IDEA THAT TEMPS WILL STILL BE ABOVE FREEZING THROUGH MOST OF THE EVENING. ANY SNOW THAT DOES FALL WILL BE LATE IN THE EVENING ACROSS THE FAR EASTERN CWA /PIKE COUNTY/...AS WELL AS ACROSS SOME OF THE HIGHEST TERRAIN NEAR THE VIRGINIA BORDER. DROPPED SNOW TOTALS SUBSTANTIALLY...WITH ONLY A COUPLE TENTHS EXPECTED IN THE HIGHEST TERRAIN. NEIGHBORING OFFICES SEEM TO HAVE FOLLOWED SUIT WITH THIS LOWER IMPACT SOLUTION AS WELL. THE PRECIPITATION SHOULD CLEAR EARLY IN THE NIGHT...WITH DRY AND COLDER AIR FILTERING IN BEHIND...EFFECTIVELY CUTTING OFF THE CLOUD COVER FROM WEST TO EAST. AS THIS COLDER AIRMASS TAKES HOLD...AND CLOUDS CLEAR...EXPECT TEMPS TO MIX OUT OVERNIGHT INTO THE MID 20S ACROSS MUCH OF THE REGION. SUNNY SKIES WILL FINALLY MAKE AN APPEARANCE DURING THE DAY TOMORROW AS HIGH PRESSURE REMAINS IN CONTROL. TEMPERATURES WILL BE ON THE COOLER SIDE COMPARED TO TODAY...BUT WILL STILL BE ABLE TO WARM UP TO ABOUT THE 40 DEGREE MARK. NAM12 FORECAST SOUNDINGS SHOW THE ATMOSPHERE BECOMING QUITE DRY...WITH DEW POINTS DROPPING SUBSTANTIALLY. THIS WILL ESPECIALLY BE THE CASE IN THE HIGHER TERRAIN WEDNESDAY NIGHT...WHERE DEW POINTS COULD DROP AS LOW AS 9 DEGREES. OVERNIGHT LOW TEMPS WILL DROP TO AROUND FREEZING OR SLIGHTLY BELOW...WITH A GOOD SET UP FOR A RIDGE VALLEY SPLIT TO OCCUR. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 341 PM EST TUE DEC 17 2013 THE EXTENDED FORECAST PERIOD BEGINS ON THURSDAY WITH A MAINLY ZONAL PATTERN OVER THE CONUS WITH AN UPPER LEVEL LOW OVER THE SOUTHWEST. THE BIG QUESTION BECOMES THE TIMING OF THE UPPER LOW AS IT MOVES TO THE EAST AND WHERE THE FRONT SETS UP OVER THE OHIO VALLEY. THE CURRENT TREND IN THE MODELS IS FOR A STRONGER LOW TO FORM ON THE FRONT TO THE WEST OF THE AREA. THIS SOLUTION WILL CREATE A SHARP WAVE ON THE FRONT AND PUSH A WARM FRONT TO THE NORTH OF THE AREA. THIS SOLUTION WOULD PRODUCE MUCH LESS RAINFALL BECAUSE THE STATIONARY FRONT WOULD STAY TO THE WEST AND NORTH OF EASTERN KENTUCKY. THE JURY IS REALLY STILL OUT ON THIS SOLUTION AND WOULD NOT BE TOO SURPRISED TO SEE A COUPLE DIFFERENT SOLUTIONS BEFORE THE WEEKEND GETS HERE. AS SUCH...TIMING OF THE SYSTEM AND THE AMOUNT OF RAINFALL IS FAIRLY LOW CONFIDENCE. IN ADDITION...HAVE SEEN THE MODELS STRUGGLE TIME AND TIME AGAIN WITH TRYING TO NAIL DOWN TRANSITIONS IN THE PATTERN LIKE THE ONE WE ARE SEEING. DID TREND THE FORECAST TO THE NEWER MODEL BLEND. ALSO WITH THIS SOLUTION...THERE WILL NOT BE MUCH TIME TO GET ANY COLD AIR INTO THE AREA AS THE FRONT MOVES THROUGH. THIS WILL DECREASE THE CHANCES FOR WINTRY PRECIPITATION ON THE BACK END OF THE FRONT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY) ISSUED AT 139 AM EST WED DEC 18 2013 THE SOLID BAND OF STRATOCU AND ASSOCIATED MVFR CIGS IS QUICKLY WORKING EAST ACROSS THE AREA WITH ANOTHER NARROW BAND OF MVFR STRATOCU BEHIND IT. CONDITIONS SHOULD BECOME VFR IN ALL AREAS THROUGH 9Z OR 10Z AND REMAIN VFR THROUGH THE END OF THE PERIOD AS SFC AND UPPER LEVEL HIGH PRESSURE BUILD IN. THE PRESSURE GRADIENT WILL ALSO RELAX OVER THE NEXT SEVERAL HOURS...WITH VALLEY LOCATIONS GRADUALLY BECOMING LIGHT AND VARIABLE AND MORE OPEN TERRAIN LOCATIONS AND RIDGES TAPERING TO AROUND 5 KT...AND LOSING RECENT GUSTINESS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...JMW LONG TERM...JJ AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1234 AM EST WED DEC 18 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 343 PM EST TUE DEC 17 2013 NOTE THAT TEMPS AT CMX REMAIN QUESTIONABLE DUE TO FAULTY FAN ON OBSERVATION EQUIPMENT. TECHNICIANS WL BE WORKING ON THIS PROBLEM TMRW. 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW PERSISTENT NW FLOW ALF BTWN DEEP UPR TROF CENTERED OVER ONTARIO AND UPR RDG OVER WRN NAMERICA. H5 TEMPS WITHIN THE TROF EXTENDING INTO THE GREAT LKS ARE AS LO AS -40C...SO THE AREA REMAINS IN THE GRIP OF WINTER CHILL. ONE SHRTWV EMBEDDED WITHIN THE UPR TROF BROUGHT SOME -SN TO THE SCNTRL CWA THIS MRNG...BUT THIS DISTURBANCE/DEEPER MSTR SHOWN ON THE 12Z GRB RAOB HAVE SHIFTED TO THE E. ANOTHER SHRTWV IS PRESENT OVER MN... BUT THIS DISTURBANCE WL BE PASSING TOO FAR TO THE S TO HAVE AN IMPACT ON UPR MI. YET ANOTHER SHRTWV IS OVER NW ONTARIO AND DROPPING SEWD. ATTENDANT SFC-H85 COLD FNT MOVED INTO WRN UPR MI THIS AFTN. 12Z INL/YPL RAOBS SHOW HI RELATIVE RH TO H6-5 AND 12Z H85 TEMPS RANGING FM -13C AT INL RIGHT BEHIND THE COLD FNT TO -24C AT YPL... WHICH WAS DEEPER INTO THE COLD AIRMASS. SO THERE ARE POCKETS OF SHSN EXTENDING UPWIND OF LK SUP IN NRN MN/ADJOINING ONTARIO. FARTHER TO THE W...THERE ARE SIGNS THE FLOW IS BECOMING A BIT MORE PROGRESSIVE...AT LEAST FOR A SHORT TIME. 00Z-12Z H3 HGT RISES UP TO 150M WERE REPORTED AT SEVERAL UPR AIR SITES FM THE NRN PLAINS INTO SCNTRL CANADA AS THE WRN RDG SHIFTS TO THE E. MAIN FCST CONCERNS IN THE SHORT TERM FOCUS ON LES POPS/AMOUNTS WITH ARRIVAL OF MORE ARCTIC AIR BEHIND EARLY AFTN/EARLY EVNG COLD FROPA. TNGT...SHRTWV IN NW ONTARIO IS FCST TO SHIFT SEWD ACRS NRN LK SUP... ACCOMPANIED BY AREA OF WEAK H85-5 QVECTOR CNVGC/SOME DEEPER MSTR AND ATTENDANT COLD FROPA. EXPECT SHSN INTENSITY/COVERAGE TO INCRS LATE THIS AFTN/EVNG W-E...ESPECIALLY IN AREAS NEAR LK SUP FAVORED BY THE WNW FLOW IN THE WAKE OF THE COLD FROPA...WHICH WL BE FOLLOWED BY AXIS OF H85 TEMPS AS LO AS -20C. ALTHOUGH NOT OUT OF THE QUESTION THERE COULD BE SOME HEAVIER SHSN IN THE FAVORED SN BELTS...ADVY SN SEEMS UNLIKELY. THE FIRST LIMITING FACTOR WL BE RELATIVELY SHORT DURATION OF THE HEAVIER LES. HGT RISES NOTED IN THE NRN PLAINS/ SCENTRAL CANADA ARE PROGGED TO FOLLOW QUICKLY THE DEPARTING SHRTWV LATER IN THE EVNG WITH VIGOUROUS DNVA/DEEP LYR QVECTOR DVGC LOWERING SUBSIDENCE INVRN TO NEAR 3K FT OVER THE KEWEENAW BY 12Z. APRCH OF SFC RDG AXIS AND SHIFTING LLVL WINDS OVER THE W UNDER THESE NEGATIVE DYNAMICS...WITH RDG AXIS ARRIVING THERE BY 12Z...WL ALSO ACT TO SUPPRESS THE SN AMOUNTS. IN FACT...SUITE OF HIER RES MODEL OUTPUT IS QUITE VARIABLE ON QPF...WITH FCSTS INCONSISTENT ON MAGNITUDE/HGT/ TIMING OF SHARPER UVV AND RELATIVE TO THE DGZ. IN THE NW WIND SN BELTS TO THE E OF MQT...SHSN WL ARRIVE DURING THE EVNG AND PERSIST THRU 12Z. LONGER FETCH OVER THE OPEN WATER WL PLAY AN ENHANCEMENT ROLE IN INTENSIFYING THE SHSN STREAMING INTO THIS AREA...BUT SHIFTING WINDS MAY LIMIT THE RESIDENCE TIME OF THE HEAVIER SHSN HERE AS WELL. THE MOST FAVORABLE FACTOR FOR HEAVIER SN OVER THE ERN CWA NEAR LK SUP WL BE THE POTENTIAL FOR LAND BREEZE CNVGC OVER FAR EASTERN ALGER/NRN LUCE COUNTIES. BUT FCST SDNGS SHOW SUBSIDENCE INVRN SINKING FAIRLY STEADY HERE AS WELL LATER AT NGT WHEN THE POTENTIAL FOR THE SHARPER LLVL CNVGC WOULD BE GREATER. AS IS TYPICAL...AREAS OVER THE SCENTRAL WL SEE NOTHING MORE THAN ISOLD -SHSN WITH DOWNSLOPE FLOW. EXPECT THE LOWEST MIN TEMPS OVER THE INTERIOR W...WHERE THERE WL BE SOME CLRG/LIGHT WINDS WITH ARRIVAL OF SFC RDG AXIS. WED...AS THE UPR FLOW TENDS TO SHIFT MORE ZONAL...A SHRTWV IS FCST TO SHIFT E THRU SCENTRAL CANADA...WITH ASSOCIATED SFC LO PRES FCST TO MOVE INTO NRN MN BY 00Z THU. GENERAL WAD/ISENTROPIC LIFT BTWN THIS SHRTWV/SFC LO AND SFC HI SHIFTING INTO THE SE CONUS WL IMPACT THE UPR GRT LKS. AS THE FLOW BACKS TO THE SW...LINGERING LES OVER THE KEWEENAW AND FAR E CWA NEAR LK SUP WL SHIFT OUT INTO THE OPEN LK. THE BULK OF THE MODELS SHOW LGT SN ASSOCIATED WITH THE SHARPER ISENTROPIC ASCENT FALLING OVER LK SUP. THE CNDN MODEL IS THE ONE EXCEPTION...AS THIS MODEL SHOWS THE SFC LO A BIT FARTHER S IN MN AND STRIPE OF LGT -SN IMPACTING APPROXIMATELY THE NE HALF OF THE CWA. GIVEN PERSISTENCE OF TROF IN ERN CANADA AND CHILL...SUSPECT THIS MODEL IS ON THE RIGHT TRACK. SO WL SHIFT THE AXIS OF CHC POPS A BIT TO THE SW INTO THE NRN LAND CWA. FEED OF RELATIVELY DRY LLVL AIR WL LIMIT ANY POTENTIAL SN ACCUM EVEN IF THE MORE PESSIMISTIC CNDN MODEL DOES VERIFY. ALSO LOWERED FCST MAX TEMPS A BIT TO REFLECT THE POTENTIAL FOR MORE TENACIOUS COLD LLVL AIR. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 457 PM EST TUE DEC 17 2013 MUCH OF THIS FCST PERIOD IS IN THE MODERATE TO LOWER CONFIDENCE RANGE. AT 00Z THURSDAY MUCH OF THE CONTINENTAL U.S. WILL BE UNDER A BROAD WEAK RIDGE TO ZONAL FLOW AT 500MB...WITH THE DOMINANT LOW SPINNING ACROSS N CANADA WITH LONGWAVE TROUGHS EXTENDING ACROSS BOTH THE WEST AND EAST COASTS. AN INITIAL BROAD SFC LOW/TROUGH WILL EXTEND NE INTO CENTRAL LAKE SUPERIOR AT 00Z. WHILE THE GFS PUSHES THE LOW E OF LAKE SUPERIOR BY 06Z THURSDAY...THE ECMWF KEEPS IT AS PART OF THE MAIN SYSTEM TO OUR S. THE RESULT IS A COMPLETELY DIFFERENT FCST FOR WEDNESDAY NIGHT...WITH LES OFF THE GFS ON STRONGER NW WINDS...WHILE THE ECMWF SOLUTION KEEPS A WAA SCHEME OVER THE AREA A BIT LONGER. THEY BOTH DO AGREE WITH SOME SORT OF LAKE ENHANCEMENT N OR NW FLOW BY THURSDAY AFTERNOON...ALTHOUGH THE GFS IS APPROX 2C COOLER NEAR THE SFC. LOOK FOR THE CANADIAN AND W COAST SYSTEMS TO DEEPEN AS THEY SINK SSE THURSDAY AND FRIDAY. AT 18Z THURSDAY THE MAIN TROUGH WILL EXTEND FROM THE S LOW OVER S CA UP THROUGH MT INTO S CANADA. A QUICK BURST OF SNOW THURSDAY NIGHT LOOKS TO BE ABOUT IT...EXCEPT FOR SOME LAKE EFFECT/LAKE ENHANCEMENT ON W TO NW WINDS OVER THE KEWEENAW PENINSULA...AND AROUND AND E OF MUNISING THROUGH ABOUT MID MORNING FRIDAY. TOTAL SNOWFALL OF 1-2IN STILL LOOK GOOD. CONFIDENCE REMAINS LOW WITH THIS SYSTEM. THE 12Z NAM DID NOT REALLY BRING ANY OF THE SYNOPTIC MOISTURE INTO UPPER MI...ALTHOUGH THE 18Z VERSION BROUGHT SNOW BACK NW SIMILARLY TO THE GFS. WILL STILL HIGHLIGHT THE POTENTIAL FOR A FEW INCHES OF SNOW LATE THURSDAY AFTERNOON INTO FRIDAY MORNING...MAINLY OVER THE HIGHER TERRAIN NEAR LAKE SUPERIOR. THE NEXT LOW OVER THE ROCKIES SATURDAY WILL EJECT NE SUNDAY...WITH UPPER MI AGAIN ON THE BACK SIDE OF THE LOW. GIVEN THE STRENGTH OF THE SYSTEM...AND SIGNIFICANT HIGH DROPPING IN FROM THE NW SUNDAY THROUGH MONDAY...MUCH COLDER AIR WILL BE ABLE TO SLIDE IN. 850MB TEMPS OF -20 TO -22C WILL BE POSSIBLE. THERE ARE SOME TIMING DIFFERENCES BETWEEN THE GFS AND ECMWF AT THIS PERIOD...BUT THEY ARE CONSISTENT WITH THE COLD AIR. FARTHER OUT...EXPECT STRONG WAA TUESDAY BEHIND THE COLD AIRMASS. WHILE TIMING IS STILL IN QUESTION...SW 40-55KT 850MB WINDS WITH SFC WINDS OF 15-25KTS LOOK LIKELY FOR A 6HR WINDOW BETWEEN 09Z TUESDAY TO 00Z WEDNESDAY. WILL NEED TO MONITOR MODEL TRENDS TO ADD MORE SPECIFICITY AS THE TIME NEARS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1233 AM EST WED DEC 18 2013 ALL SITES SHOULD SEE GENERAL IMPROVEMENT THROUGH WED MORNING AS CONDITIONS BECOME LESS FAVORABLE FOR LAKE EFFECT CONDITIONS DUE TO HIGH PRESSURE MOVING INTO THE REGION. A WEAK LOW PRESSURE SYSTEM WILL MOVE THROUGH THE AREA TOWARD THE END OF THE TAF PERIOD...SO INTRODUCED WORSENING CONDITIONS AS LOW LEVEL MOISTURE INCREASES. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 343 PM EST TUE DEC 17 2013 EXPECT NW WINDS TO 25-30 KTS THIS EVENING BEHIND A COLD FRONTAL PASSAGE TO DIMINISH AND BACK TO THE SW WITH APPROACH OF A HI PRES RIDGE LATER TONIGHT INTO WED. A VERY CHANGEABLE WEATHER PATTERN WILL THEN DOMINATE THE UPPER GREAT LAKES THE REST OF THE WEEK...WITH HARD TO TIME DISTURBANCES IMPACTING LAKE SUPERIOR. CONFIDENCE IS LOW IN TIMING THESE DISTURBANCES AND ACCOMPANYING WIND SHIFTS...BUT GALES APPEAR UNLIKELY THRU THE FORECAST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...KF AVIATION...TITUS MARINE...KC
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
401 AM CST WED DEC 18 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 400 AM CST WED DEC 18 2013 AT THIS TIME YESTERDAY MORNING...THE FORECAST AREA WAS 15-30 DEGREES WARMER THAN WE ARE CURRENTLY. THE THERMOMETER WILL GET A WORKOUT TODAY AND EVEN AFTER A CHILLY START...WE SHOULD REBOUND QUITE WELL BY THE AFTERNOON. THE SURFACE RIDGE WILL BE OUT OVER LAKE MICHIGAN BY 15Z AND THE APPROACHING CLIPPER SHOULD BE NEARING THE WESTERN MN BORDER AROUND THE SAME TIME. THE WARM AIR ADVECTION OUT AHEAD OF THE SURFACE LOW THIS MORNING IS IMPRESSIVE AND IT`S THE REASON WE`RE FORECASTING THE WARMEST TEMPERATURES WE`VE SEEN IN OVER TWO WEEKS. THE 18.07Z RAP HAS NEARLY THE ENTIRE FORECAST AREA ABOVE 0C AT 925MB BY 00Z THIS EVENING /6-10C ACROSS MUCH OF WESTERN MN/ AND YOU`RE NOT SEEING THINGS...THAT IS INDEED THE 0C ISOTHERM NEAR THE MN/IA BORDER AT 700 MB. THIS SAME BUBBLE OF WARM AIR WAS OVER WESTERN NE AND SD YESTERDAY AND BROUGHT HIGHS BETWEEN 40-60. NOW THE WARMEST TEMPS WERE IN SNOW FREE AREAS...BUT LOWER 40S WERE OBSERVED EVEN WHERE THERE WAS SNOW ON THE GROUND. WE WILL CERTAINLY BE COOLER THAN WHAT THE PLAINS OBSERVED YESTERDAY...BUT THE DOWNSLOPE AREAS OF THE BUFFALO RIDGE COULD EASILY SEE SOME LOWER 40S...ESPECIALLY IF WE ESTABLISH A SOUTHWEST COMPONENT TO THE WIND BEFORE THE NOON HOUR. THE MIXING WILL NOT BE GREAT TODAY...ESPECIALLY WITH THE MORNING INVERSION AND SNOW COVER. WE SHOULDN`T MIX AS HIGH AS 925MB AND THIS WILL KEEP HIGHS FROM GETTING TOO WARM. WE HOPE THIS LACK OF MIXING DOESN`T MEAN WE`RE MUCH TOO WARM WITH THE TEMPS TODAY - VERIFICATION HAS SHOWN A WARM BIAS LATELY - THOUGH THAT HAS BEEN WITH 15 TO 30 DEGREE DEPARTURES FROM NORMAL. WE LIKE THE 18.00Z NAM MOS IN THAT IT KEPT THE WESTERN FORECAST AREA WARM AND COOLED THE EAST. THERE SHOULD BE A LARGE WEST-EAST TEMPERATURE GRADIENT TODAY /LOWER 40S FAR WEST - MID TO UPPER 20S FAR EAST/. THE TWIN CITIES METRO IS RIGHT IN THE MIDDLE OF THIS GRADIENT. THERE IS VIRTUALLY NO CHANCE FOR PRECIP IN THE SHORT TERM...BUT PATCHY BLOWING SNOW CAN NOT BE COMPLETELY RULED OUT LATE TONIGHT WHEN A PRONOUNCED AREA OF MSLP PRESSURE RISES SLIDES ACROSS MN BEHIND THE CLIPPER SYSTEM. WE SAW BLOWING SNOW YESTERDAY IN WESTERN MN...BUT THAT WAS WITH BL WINDS THAT WERE 5-7 KTS STRONGER. IN ADDITION...THE WARMER TEMPS TODAY SHOULD PROBABLY ACT TO SETTLE THE CURRENT SNOW PACK A BIT. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 400 AM CST WED DEC 18 2013 ARCTIC AIR WILL OOZE IN ON THURSDAY AS A 1035MB HIGH BUILDS SOUTHWARD INTO THE WESTERN HIGH PLAINS. WHILE THIS IS OCCURRING... A SHORT WAVE WILL MOVE EAST FROM THE NORTHERN ROCKIES DURING THE DAY BRINGING A SURGE OF MID LEVEL MOISTURE TO THE REGION. AMPLE UPGLIDE... SATURATION AND ADIABATIC OMEGA ON THE NAM/GFS 290K THETA SURFACES SPREAD INTO WEST CENTRAL MN BY NOON ON THURSDAY AND ACROSS THE CWA BY EVENING. MIXING RATIOS RISE TO BETWEEN 2 AND 3 G/KG. HOWEVER...THE BEST ADIABATIC OMEGA ONLY LASTS FOR ABOUT 6 HOURS. CONTINUED THE TREND OF RAISING POPS WITH LIKELY FOR THURSDAY AFTERNOON IN WEST CENTRAL MN WITH CATEGORICAL IN PLACE FROM SOUTHWEST MN THROUGH THE TWIN CITIES AND ACROSS MUCH OF WEST CENTRAL WI FOR THURSDAY EVENING. THE SNOW THEN TAPERS OFF GRADUALLY OVERNIGHT FROM WEST TO EAST WITH SOME LINGERING LIGHT SNOW FOR SOUTH CENTRAL MN THROUGH WEST CENTRAL WI ON FRIDAY. SNOW AMOUNTS OF 1.5 TO 2 INCHES ARE LIKELY BY DAYBREAK FRIDAY... ESPECIALLY ON AN EAST-WEST AXIS THAT RUNS THROUGH THE SOUTH METRO...WITH A FEW MORE TENTHS OF AN INCH ON FRIDAY TO THE EAST AND SOUTH OF THE METRO. THE HIGH TO OUR WEST WILL BUILD IN FOR SATURDAY WITH A DRY BUT COLD DAY. DIFFERENCES THEN EVOLVE BETWEEN THE ECMWF...GFS AND GEM ON THE LATTER HALF OF THE WEEKEND AS A STORM SYSTEM EXITS THE SOUTH PLAINS. THE ECMWF REMAINS DRY WITH THE NORTHWEST EDGE OF THE PRECIPITATION FROM THIS SOUTHERN SYSTEM STAYING TO OUR SOUTHEAST. THE GEM GOES HOG WILD DEVELOPING A CLOSED H7 LOW OVER US BY SATURDAY NIGHT WITH 3 TO 5 INCHES OF SNOW FOR SATURDAY NIGHT AND SUNDAY. THE GFS IS IN BETWEEN...HAVING TROUBLE SEPARATING THE NORTHERN AND SOUTHERN STREAM ENERGY. COLLABORATION WAS TO FOLLOW MORE OF THE DRY ECMWF SOLUTION AND REDUCE POPS FROM THE CR EXTEND. A SECOND ARCTIC HIGH WILL BUILD IN FROM SUNDAY INTO MONDAY WITH SOME VERY COLD AIR. DROPPED LOWS TO NEAR 15 BELOW FOR PORTIONS OF CENTRAL MN FOR MONDAY MORNING WITH AROUND 5 BELOW IN THE TWIN CITIES AND ZERO IN EAU CLAIRE. THIS MAY NOT BE COLD ENOUGH IF THE ECMWF IS CORRECT WITH IT/S GUIDANCE SUGGESTING LOWERING LOWS ANOTHER 5 TO 10 DEGREES. SOME MODERATION IS EXPECTED BY CHRISTMAS EVE DAY AS THE FLOW ALOFT BECOMES MORE WESTERLY AND THE HIGH DEPARTS TO OUR SOUTHEAST. HOWEVER...ANOTHER SHORT WAVE AND LOW PRESSURE SYSTEM ARE RIDING THE ARCTIC FRONT WITH SOME MORE SNOW POSSIBLE CHRISTMAS EVE AND CHRISTMAS DAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1008 PM CST TUE DEC 17 2013 VFR CONDITIONS THROUGHOUT PERIOD. SOME MID/HIGH LEVEL CLOUDS OUT AHEAD OF NEXT COLD FRONT WHICH WILL MOVE INTO CENTRAL MN AFTER 00Z.19. SURFACE WINDS BECOMING SOUTH/SOUTHEAST INTO THE MORNING AND THEN SOUTHWEST TO WEST AHEAD OF COLD FRONT. INITIAL FROPA WILL YIELD NW WINDS BUT GENERALLY LESS THAN 10 KNOTS. WINDS WILL LIKELY INCREASE AS ARCTIC FRONT SAGS INTO THE AREA AFTER 06Z.19. KMSP...VFR CONDITIONS. SURFACE WINDS BECOMING SOUTHEAST/SOUTH OVERNIGHT AND INTO WEDNESDAY...BEFORE BECOMING SOUTHWEST LATE AFTERNOON AND NORTHWEST AFTER 03Z.19. /OUTLOOK FOR KMSP/ THU...MVFR CIGS WITH IFR/-SN POSSIBLE. WINDS N 10-15 KT. FRI...MVFR CIGS WITH LINGERING IFR/-SN POSSIBLE. WINDS N 10-15 KT. SAT...MAINLY VFR. MVFR CIGS POSSIBLE. WINDS S 5 KT BCMG NW. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...CLF LONG TERM...RAH AVIATION...DWE
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
333 AM CST WED DEC 18 2013 .SHORT TERM...TODAY THROUGH FRIDAY VERY GOOD AGREEMENT AMONGST THE MODELS WITH THE UPPER LEVEL AND SURFACE FEATURES TO AFFECT OUR REGION THROUGH FRIDAY. FOR TODAY...A SURFACE LOW PRESSURE AREA IN CANADA THIS MORNING WILL DESCEND SOUTHEAST ALONG A STRONG NORTHWEST TO SOUTHEAST FRONTAL ZONE BISECTING THE UPPER MIDWEST. TEMPERATURES THROUGH THIS FRONTAL ZONE EARLY THIS MORNING RANGED FROM THE TEENS BELOW ZERO IN NORTHEAST MINNESOTA TO 45 TO 50 DEGREES IN SOUTHWEST SOUTH DAKOTA. THE MUCH COLDER AIR THAT WILL AFFECT OUR REGION IS SITUATED BEHIND THIS SURFACE LOW PRESSURE AREA IN CANADA EARLY THIS MORNING. UNTIL THIS MOVES IN TONIGHT...THE CWA WILL EXPERIENCE ANOTHER ABOVE NORMAL TEMPERATURE/MILD DAY AS THE WARM FRONT OUT WEST PUSHES EAST IN ADVANCE OF THE SURFACE LOW. SOUTH TO SOUTHEAST WINDS THIS MORNING WILL TURN WEST AND NORTHWEST THROUGH THE DAY. THE ISSUE TODAY WILL BE HOW MUCH OF THE WARMER AIR ALOFT WILL BE REALIZED AT THE SURFACE AS THERE WILL BE A STRONG INVERSION ACROSS THE CWA. DUE TO THIS INVERSION...THE STRONGER WEST TO NORTHWEST WINDS OFF THE SURFACE WILL HAVE A HARD TIME MIXING DOWN. THE SNOW COVER HAS ALSO DIMINISHED SOME ACROSS THE CWA OVER THE LAST FEW DAYS RANGING GENERALLY FROM 1 TO 4 INCHES. HIGH RH ON TSCTS AND CLOUDS ON SATELLITE SHOWS THAT THE AREA SHOULD BE COVERED BY AN EXPANSIVE DECK OF MID AND HIGH LEVEL CLOUDS THROUGH THE DAY...INHIBITING SURFACE HEATING. TEMPERATURES EARLY THIS MORNING ACROSS THE CWA WERE ALREADY IN THE UPPER TEENS TO MID 20S WITH 50S OFF THE SURFACE ACROSS THE CWA. THUS...DO EXPECT THE REGION TO WARM INTO THE MID 30S TO THE MID 40S WITH SOME UPPER 40S FAR SOUTHWEST IN THE CWA BY LATE THIS AFTERNOON MELTING MORE SNOW...ESPECIALLY SOUTHWEST IN THE CWA. AS THE SURFACE LOW PRESSURE AREA PASSES BY...A STRONG ARCTIC FRONT WILL DROP ACROSS THE REGION TONIGHT. THIS WILL BRING BLUSTERY NORTH TO NORTHEAST WINDS ALONG WITH A BIG FALL IN TEMPERATURES TONIGHT. EXPECT LOWS TONIGHT IN THE SINGLE DIGITS AND LOWER TEENS ACROSS THE CWA. THURSDAY WILL REMAIN VERY COLD WITH LITTLE IF ANY RISE IN TEMPERATURES THROUGH THE DAY. THE OTHER ISSUE FOR LATER TONIGHT THROUGH THURSDAY EVENING WILL BE THE LIGHT SNOW DEVELOPING. SHORT WAVE ENERGY DROPPING IN FROM THE NORTHWEST ALONG WITH THE WARM AIR RIDING OVER THE ARCTIC AIR AND RR UPPER LEVEL JET SUPPORT WILL BRING LIGHT SNOW INTO THE NORTHWEST CWA LATER TONIGHT. THIS LIGHT SNOW WILL DEVELOP SOUTH AND THEN EAST INTO THURSDAY. THE BEST CHANCES OF LIGHT SNOW AND DECENT ACCUMULATIONS WILL REMAIN FROM MOBRIDGE TO PIERRE AND THEN EAST OVER TO MILLER AND TO WATERTOWN WITH 1 TO 3 INCHES POSSIBLE. WITH DRIER ARCTIC AIR PUSHING IN ALONG WITH LESS LIFT...THE SNOW AND ACCUMULATIONS ARE EXPECTED TO BE LIGHTER FROM ABERDEEN TO SISSETON TO WHEATON MAYBE AN INCH OR LESS. THE OTHER ISSUE WILL BE THE BLUSTERY NORTH TO NORTHEAST WINDS DEVELOPING WITH THE STRONG CAA AND A TIGHTENING SURFACE PRESSURE GRADIENT. COULD SEE WINDS OF 20 TO 30 MPH DEVELOPING WHICH WILL BRING SOME BLOWING SNOW AND FALLING WIND CHILLS. THE LIGHT SNOW WILL MOVE OUT...WINDS WILL FALL OFF QUICKLY AND SKIES WILL CLEAR THURSDAY NIGHT AS SURFACE HIGH PRESSURE SETTLES OVER THE REGION. WITH THE NEW SNOW COVER...LIGHT WINDS AND CLEAR SKIES...TEMPERATURES WILL FALL TO BELOW ZERO ACROSS ALL OF THE CWA WITH MAYBE SOME TEENS BELOW ZERO IF CONDITIONS ARE RIGHT. WITH WINDS TURNING SOUTH BEHIND THE EXITING SURFACE HIGH PRESSURE AREA ON FRIDAY...TEMPERATURES WILL HAVE A LONG WAY TO GO WITH WEAK SURFACE WAA. WITH THE NEW SNOW COVER AND MOSTLY SUNNY SKIES...TEMPERATURES WILL STRUGGLE TO MAKE IT TO 10 DEGREES IN THE EASTERN CWA WITH 15 TO AROUND 20 DEGREES OUT WEST. .LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY THE PERIOD OPENS WITH AN UPPER TROUGH SITTING OVER THE REGION. THE UPPER FLOW FLATTENS SLIGHTLY ON MONDAY BEFORE ANOTHER TROF SHIFTS IN ON TUESDAY. MONDAY NIGHT/TUESDAY MORNING A COLD FRONT MOVES THROUGH THE PLAINS. EARLY TUESDAY THERE MAY BE ENOUGH MIXING AHEAD OF THE FRONT TO POP THE TEMPERATURES UP INTO THE 20S...BUT IF THE GFS TIMING IS CORRECT TEMPS WILL THEN FALL THROUGH THE DAY. THE ECMWF IS A LITTLE SLOWER AND WOULD GIVE SD A SLIGHTLY LONGER REPRIEVE FROM THE ANTICIPATED WELL BELOW NORMAL TEMPS FORECAST FOR THE EXTENDED. THERE ARE NO WELL DEFINED CHANCES OF PRECIP DURING THE EXTENDED. SOME CAA SHORTWAVE SNOW SHOWERS ARE POSSIBLE AT VARIOUS TIMES BUT FORECASTER CONFIDENCE WOULD BE VERY LOW IN TRYING TO PIN DOWN ANY EXACT TIMING OR LOCATION. THEREFORE STUCK WITH ALLBLEND AND ITS MOSTLY DRY CONSENSUS. && .AVIATION... 06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS VFR CONDITIONS WILL PREVAIL ACROSS THE AREA OVERNIGHT AND THROUGH THE DAY WEDNESDAY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ SHORT TERM...MOHR LONG TERM...WISE AVIATION...PARKIN WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS TUCSON AZ
535 AM MST WED DEC 18 2013 .SYNOPSIS...EXPECT UNSEASONABLY WARM TEMPERATURES AGAIN TODAY UNDER A BLANKET OF HIGH LEVEL CLOUDS. A LOW PRESSURE SYSTEM WILL THEN BRING GUSTY WINDS THURSDAY AFTERNOON FOLLOWED BY A GOOD CHANCE OF VALLEY RAIN AND MOUNTAIN SNOW LATE THURSDAY NIGHT INTO EARLY SATURDAY. COLDER TEMPERATURES WILL ALSO OCCUR FRIDAY THROUGH THE WEEKEND. CLEARING FROM THE WEST SUNDAY WITH DRIER CONDITIONS AND A SLOW WARMING TREND EARLY NEXT WEEK. && .UPDATE...12Z TUCSON SOUNDING IS IN AND IT LOOKS FAIRLY SIMILAR TO TUESDAY WITH A SUGGEST HIGH IN TUCSON OF 85 DEGREES. THAT WOULD TIE THE ALL-TIME DECEMBER HIGH TEMPERATURE. CURRENT CIRRUS OVER THE AREA RATHER THIN BUT THERE IS A THICKER DECK OVER NORTHERN BAJA WHICH WILL MOVE OVER THE AREA LATER THIS MORNING. THIS SHOULD KEEP TEMPERATURES FROM REACHING ITS POTENTIAL...HOWEVER SINCE MOST OF THE AREA IS STARTING OFF WARMER THAN TUESDAY...BELIEVE MY CURRENT FORECAST HIGHS FOR THE AREA ARE NOT WARM ENOUGH. LATEST RUNS OF THE HRRR AND RAP SHOWS HOURLY TEMPERATURES IN TUCSON THIS AFTERNOON OF 81 AND 82 RESPECTIVELY. WITH THAT IN MIND...WILL MAKE A QUICK UPDATE AND RAISE HIGHS UP TO 2 DEGREES. DAYSHIFT WILL CONTINUE TO MONITOR IN CASE ANOTHER UPDATE IS NEEDED. && .DISCUSSION...CONSIDERABLE HIGH CLOUDS ACROSS THE AREA THIS MORNING PROVIDING A MILD DECEMBER NIGHT. SW FLOW ALOFT WILL KEEP THESE CLOUDS AROUND FOR MOST OF THE DAYLIGHT HOURS AND THUS LIMITING HEATING. AFTER A VERY WARM TUESDAY WHERE SOME SPOTS SET/TIED RECORD HIGHS FOR THE 17TH...HIGHS TODAY WILL GENERALLY BE 2-8 DEGREES COOLER. THERE IS A BACK EDGE TO THESE CLOUDS SO EXPECT CLEARING SKIES FROM SW TO NE. WITH LESS CLOUD COVER...OVERNIGHT LOWS WILL BE COOLER THAN THIS MORNING. OUR NEXT WEATHER MAKER WILL BE IMPACTING THE PACIFIC NW TODAY. AS THIS SYSTEM DROPS SOUTH AND DEEPENS OVER THE NEXT 24-36 HOURS...THE PRESSURE GRADIENT WILL BE TIGHTENING UP FOR BREEZY TO LOCALLY WINDY CONDITIONS ON THURSDAY. MODELS PRETTY SIMILAR IN SHOWING A CLOSED 540DM LOW NEAR LOS ANGELES BY LATE THURSDAY AFTERNOON. ADDITIONALLY OVER THE NEXT 24-36 HOURS...THE HIGH PRECIPITABLE WATER VALUES THAT ARE OVER SOUTHERN BAJA AND TO ITS SOUTH...WILL START TO WORKS ITS WAY NORTH ACROSS SONORA MEXICO. MOISTURE ASSOCIATED WITH THE UPPER LOW WILL ALSO INCREASE ACROSS NORTHERN BAJA CALIFORNIA. CLOSED LOW IS FORECAST TO BE OVER NORTHERN BAJA THURSDAY NIGHT WITH SHOWERS DEVELOPING OVER OUR WESTERN AREAS. HAVE INCREASED POPS WEST OF TUCSON INTO THE 20-40% RANGE. THIS CLOSED LOW WILL CONTINUE TO MOVE EAST ACROSS NORTHERN SONORA ON FRIDAY WITH MOISTURE INCREASING OUT AHEAD OF LOW. HAVE INCREASED POPS...ESPECIALLY SOUTH OF TUCSON. ALSO ADDED SLIGHT CHANCE OF THUNDER ALONG THE BORDER WHERE -24C 500 MB AIR WILL RESIDE. ALSO UPPER QPF VALUES AND SNOW AMOUNTS FOR AREAS NEAR THE BORDER. SNOW LEVELS WILL BE LOWERING INTO THE 5500` TO 6500` LEVEL WITH 2-8 INCHES OF SNOW ABOVE 6000 FEET WITH HIGHEST TOTALS ACROSS THE SOUTHERN MOUNTAIN RANGES. WE MAY EVENTUALLY NEED A WINTER WEATHER ADVISORY FOR THESE RANGES ON FRIDAY. IT WILL BE MUCH COOLER WITH HIGHS MOSTLY IN THE 50S FOR THE LOWER ELEVATIONS. STORM TOTAL QPF WILL RANGE FROM 0.20" TO 0.80" WITH HIGHEST VALUES ACROSS SOUTHERN TOHONO OODHAM NATION EAST ACROSS SANTA CRUZ COUNTY AND THE SOUTHERN HALF OF COCHISE COUNTY. SYSTEM EJECT EAST INTO WEST TEXAS ON SATURDAY WITH LINGERING SHOWERS CONTINUING EASTERN AREAS A FAST MOVING SYSTEM DIVES IN FROM THE NORTH OF BACK SIDE OF LOW. HIGHS ON SATURDAY WILL REMAIN RATHER COOL. WARMER AND DRY ON SUNDAY WITH WARMING TREND CONTINUING INTO THE FIRST HALF OF NEXT WEEK. && .AVIATION...BKN-OVC CLOUDS MAINLY ABOVE 20K FT AGL THRU 19/04Z... THEN CLEARING SKIES FROM WEST TO EAST. ELY/SELY SURFACE WIND AT 10-15 KTS IN SOME AREAS THIS MORNING...PERSISTING THRU 18/18Z INCLUDING KTUS...OTHERWISE SURFACE WIND LESS THAN 10 KTS. NORMAL DIURNAL SURFACE WIND TRENDS ARE EXPECTED THIS AFTERNOON AND EVENING WITH SURFACE WIND SPEEDS LESS THAN 10 KTS. STRONG AND GUSTY SURFACE WINDS WILL DEVELOP THURSDAY MORNING...AND CONTINUE THROUGH THURSDAY NIGHT AS A STORM SYSTEM MOVES INTO THE REGION. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...DRY CONDITIONS WILL PREVAIL THROUGH THURSDAY. EXPECT BREEZY CONDITIONS THURSDAY AFTERNOON AHEAD OF A LOW PRESSURE SYSTEM MOVING INTO THE REGION. A FEW LOCALES IN COCHISE COUNTY MAY BRIEFLY EXPERIENCE RED FLAG CONDITIONS THURSDAY AFTERNOON. THE LOW PRESSURE SYSTEM WILL BRING A CHANCE OF SHOWERS MAINLY WEST OF TUCSON THURSDAY NIGHT. VALLEY RAIN AND MOUNTAIN SNOW ARE THEN LIKELY ON FRIDAY AND FRIDAY NIGHT FOR MUCH OF SOUTHEAST ARIZONA. EXPECT A FEW LINGERING SHOWERS MOSTLY EAST OF TUCSON ON SATURDAY...THEN DRY CONDITIONS WILL RETURN SUNDAY THROUGH NEXT TUESDAY. && .TWC WATCHES/WARNINGS/ADVISORIES...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
AREA FORECAST DISCUSSION
NWS ALBANY NY
944 AM EST WED DEC 18 2013 .SYNOPSIS... AN UPPER LEVEL DISTURBANCE CROSSING THE REGION WILL BRING SCATTERED SNOW SHOWERS AND FLURRIES INTO THE EARLY AFTERNOON. LAKE EFFECT SNOW SHOWERS OR SNOW SQUALLS WILL IMPACT PORTIONS OF THE WESTERN ADIRONDACKS THIS AFTERNOON AND TONIGHT. HIGH PRESSURE WILL BUILD IN FROM THE SOUTHWEST FOR THURSDAY...BRINGING MILDER TEMPERATURES...AND DRY CONDITIONS. A FRONTAL SYSTEM APPROACHING FROM THE WEST AND NORTH WILL BRING CLOUDS...ALONG WITH SOME SNOW AND RAIN SHOWERS FOR THURSDAY NIGHT INTO FRIDAY. A MORE SIGNIFICANT STORM SYSTEM MAY BRING WIDESPREAD PRECIPITATION FOR A PORTION OF THE UPCOMING WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 943 AM EST...THE LATEST RUC SHOWS THE H500 TROUGH AXIS...AND ITS ASSOCIATED MID LEVEL SHORT-WAVE MOVING ACROSS WRN NEW ENGLAND. SOME SCT SNOW SHOWER AND FLURRIES HAVE OCCURRED FROM THE CAPITAL REGION NORTH AND WEST...AND ESPECIALLY ALONG THE SPINE OF THE SRN GREENS...N-CNTRL TACONICS...AND BERKSHIRES. SOME SLIGHT AND LOW CHC POPS HAVE BEEN KEPT IN THE FORECAST INTO THE EARLY PM. MOSTLY CLOUDY CONDITIONS PERSIST NORTH OF THE MID HUDSON VALLEY AND NW CT. FURTHER UPSTREAM...DIFFUSE LAKE EFFECT ACTIVITY IS SETTING UP JUST DOWN STREAM OF LAKE ONTARIO. THIS ACTIVITY SHOULD ORGANIZE BETTER IN THE EARLY PM...AND THE LAKE EFFECT SNOW ADVISORY BEGINS FOR NRN HERKIMER AND HAMILTON COUNTIES AT 3 PM. CURRENT FORECAST TRENDS LOOK SIMILAR FOR 3 TO 6 INCHES OF HIGH RATIO SNOWFALL. THE FORECAST TREND LOOKS SIMILAR FOR THE LAKE POTENTIAL BELOW. THE LAKE RESPONSE WILL DEVELOP IN THE PM...AS COOLING WITHIN THE 850-700 MB LAYER COMBINES WITH AN INCREASING LOW LEVEL FLOW OVER WATER TRAJECTORY ACROSS LAKE ONTARIO...WITH SOME ADDITIONAL MOISTENING FROM LAKE HURON. IT APPEARS THAT THE LAKE EFFECT POTENTIAL FOR SINGLE SNOWBANDS WILL BE FOR A SOMEWHAT SHORT DURATION...MAINLY AFTER NOON TODAY...THROUGH AT LEAST 6 PM EST. EXPECT SEVERAL INCHES OF SNOW ACROSS PORTIONS OF NORTHERN HERKIMER CO...AND POSSIBLY EXTENDING INTO PORTIONS OF WEST CENTRAL AND NORTHWEST HAMILTON CO...MAINLY THIS AFTERNOON. SOME EXTENSION OF A SNOWBAND MAY ALSO IMPACT PORTIONS OF THE MOHAWK VALLEY/WRN CAPITAL REGION EARLY THIS THIS AFTERNOON...WITH MINOR ACCUMS POSSIBLE. ENHANCED UPSLOPE ACROSS PORTIONS OF SOUTHERN VT COULD ALSO LEAD TO A COUPLE INCHES OF SNOWFALL ACROSS EASTERN PORTIONS OF BENNINGTON CO AND WEST CENTRAL WINDHAM CO THIS AFTERNOON. AS FOR TEMPS...HAVE SIDED A BIT BELOW A MAV/MET MOS BLEND...WITH UPPER 20S TO LOWER 30S EXPECTED IN MOST VALLEY AREAS...AND MAINLY 20S FOR HIGHER ELEVATIONS. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... TONIGHT...THE AFOREMENTIONED SNOWBAND WILL LIKELY BE ONGOING THIS EVENING ACROSS THE ADVISORY AREA...AND LIFTING NORTHWARD...IMPACTING AREAS NEAR AND NORTH OF ROUTE 28. LATER TONIGHT...IT APPEARS THAT THE BAND SHOULD WEAKEN AS THE INVERSION LEVEL DROPS RAPIDLY...AND LOW LEVEL DIRECTIONAL SHEAR INCREASES AND DISRUPTS SINGLE BAND POTENTIAL. ELSEWHERE...EXPECT PARTLY CLOUDY SKIES...ALTHOUGH SOME PERIODS OF MOSTLY CLEAR SKIES WILL BE POSSIBLE. GIVEN OUR DEEP...FRESH SNOWPACK...ANY BREAKS IN THE CLOUDS WILL ALLOW TEMPS TO QUICKLY DROP. HAVE THEREFORE WENT BELOW THE COLDEST GUIDANCE...WITH MAINLY SINGLE DIGITS AND TEENS EXPECTED. SHOULD BREAKS IN THE CLOUDS BE MORE WIDESPREAD AND/OR LONGER IN DURATION...EVEN COLDER MIN TEMPS WOULD BE POSSIBLE. THU...LOW AND MID LEVEL WARM ADVECTION DEVELOPS AND STRENGTHENS. AS MILDER AND INCREASINGLY MOIST AIR MOVES OVER THE VERY COLD GROUND AND DEEP SNOW COVER...IT APPEARS THAT A LOW LEVEL INVERSION WILL DEVELOP...LEADING TO MOSTLY CLOUDY SKIES FOR AT LEAST THE NORTHERN THIRD OF THE REGION...WITH OCCASIONAL CLOUDS TO THE SOUTH. FOR MAX TEMPS...HAVE SIDED WITH THE COOLER OF THE MAV/MET MOS...WITH GENERALLY 30S EXPECTED FOR VALLEY AREAS...AND 20S TO AROUND 30 FOR HIGHER ELEVATIONS. THU NT-FRI NT...A FRONTAL BOUNDARY WILL GRADUALLY APPROACH FROM THE N AND W...AS WAVES OF LOW PRESSURE TRAVEL ALONG IT. SEVERAL SURGES OF ISENTROPIC LIFT WILL IMPACT THE REGION...ESP NORTHERN AND CENTRAL AREAS. IT APPEARS THAT THE BEST CHC FOR PRECIP WILL BE LATE THU NT INTO FRI EVENING. WARMING ALOFT COULD ALLOW FOR SOME MIXED PRECIP TO OCCUR ACROSS NORTHERN AREAS THU NT...AND AGAIN FRI NT...AND WILL HAVE TO WATCH MODEL TRENDS AND LOW LEVEL THERMAL PROFILES. QPF LOOKS LIGHT AT THIS TIME...BUT CAN NOT RULE OUT SOME AREAS OF LIGHT ICING...ESP FRI NT ACROSS PORTIONS OF THE SOUTHERN ADIRONDACKS AND WESTERN MOHAWK VALLEY. HAVE SIDED WITH...OR WENT BELOW THE COOLER MAV/MET...WITH NIGHTTIME MINS FALLING INTO THE 20S IN MOST AREAS...AND MAX TEMPS RANGING FROM THE UPPER 20S TO MID 30S ACROSS NORTHERN AREAS...AND MID 30S TO MID 40S ACROSS SOUTHERN AREAS. && .LONG TERM /SATURDAY THROUGH TUESDAY/... STILL DECENT AGREEMENT IN GUIDANCE AND ENSEMBLES FOR A STRONG WARM ADVECTION EVENT THAT SHOULD RESULT IN MORE RAIN THAN WINTRY PRECIPITATION. ONE SYSTEM WILL BE EXITING THROUGH SATURDAY MORNING WITH JUST SCATTERED RAIN AND SNOW SHOWERS ENDING. THE NEXT SYSTEM...WITH SOUTHERN STREAM ORIGINS...SPREADS MOSTLY RAIN OVER MUCH OF THE REGION SATURDAY AFTERNOON...STARTING AS A MIX IN THE SOUTHERN ADIRONDACKS. THERE COULD BE MINOR TO MODERATE ACCUMULATIONS OF MIXED PRECIPITATION...INCLUDING POSSIBLY FREEZING RAIN...IN THE SOUTHERN ADIRONDACKS THROUGH SATURDAY NIGHT BEFORE PRECIPITATION TURNS TO RAIN SUNDAY MORNING. THIS COULD BE A PROLONGED EVENT...WITH A VERY STRONG WEST SOUTHWESTERLY BOUNDARY LAYER JET AND DEEP MOISTURE...ALONG WITH STRONG ISENTROPIC LIFT WITHIN THE WARM ADVECTION...AND STRONG FRONTOGENESIS ALONG THE COLD FRONT. THERE COULD BE ENOUGH RAIN FOR SOME POTENTIAL RUN OFF PROBLEMS WHEN COMBINED WITH SNOW MELT. THE AXIS OF HEAVIEST RAIN LOOKS TO BE ALONG AND NORTH OF THE SCHOHARIE VALLEY...SOUTHERN ADIRONDACKS...HELDERBERGS TO THE LAKE GEORGE SARATOGA REGION...SOUTHERN GREEN MOUNTAINS AND BERKSHIRES. SOME INDICATIONS ARE THAT THE HEAVIEST RAIN COULD BE MOSTLY THE EXTREME NORTHERN SECTIONS OF THE FORECAST AREA...SO THERE IS CONSIDERABLE UNCERTAINTY ON WHERE THE HEAVIEST RAIN COULD FALL. THE POTENTIAL FOR HEAVY RAIN...SNOW MELT AND RUN OFF WILL BE ADDRESSED IN THE HWO. HIGHS SATURDAY IN THE 40S...MID TO UPPER 30S SOUTHERN ADIRONDACKS AND SOUTHERN GREEN MOUNTAINS. HIGHS SUNDAY IN THE LOWER TO MID 50S...WITH 40S IN HIGHER ELEVATIONS...AROUND 40 SOUTHERN ADIRONDACKS. THE FRONT TRACKS THROUGH SUNDAY NIGHT AND EARLY MONDAY WITH DEEP COLD ADVECTION SPREADING ACROSS OUR REGION. HIGHS MONDAY IN THE LOWER TO MID 30S...WITH UPPER 20S IN THE SOUTHERN ADIRONDACKS AND SOUTHERN GREEN MOUNTAINS. COLD ADVECTION CONTINUES TUESDAY WITH HIGHS IN THE 20S...UPPER TEENS IN THE SOUTHERN ADIRONDACKS. THERE COULD BE LAKE EFFECT SNOW BANDS MONDAY INTO TUESDAY BUT THE INLAND EXTENT IS IN QUESTION. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... AN UPPER LEVEL DISTURBANCE TRACKING THROUGH THE REGION WILL BRING PERIODS OF BROKEN CEILINGS ABOVE 3000 FEET THROUGH THE DAY. THERE COULD BE SOME FLURRIES THIS MORNING SO WILL PUT VCSH FOR A FEW HOURS AT KALB...KPSF...AND KGFL. AT THE SURFACE...HIGH PRESSURE WILL BUILD IN. SCATTERED VARIABLE BROKEN CEILINGS ABOVE 3000 FEET SHOULD CONTINUE THROUGH TONIGHT MAINLY AT KALB...KPSF AND KGFL BUT JUST SCATTERED AT KPOU. WINDS WILL BE LIGHT TO CALM THROUGH THE EARLY MORNING HOURS BECOMING WESTERLY DURING THE LATE MORNING AND INCREASING TO 6 TO 10 KNOTS. SOME GUSTS INTO THE TEENS ARE EXPECTED AT KALB AND KPSF FROM LATE MORNING THROUGH THE MID AFTERNOON...AND SHOULD CONTINUE INTO THE EVENING. WINDS SHOULD DECREASE TO 5 KT OR LESS LATER THIS EVENING AND CONTINUE THROUGH THE NIGHT. OUTLOOK... THURSDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. FRIDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN. FRIDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN. SATURDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...RA. SATURDAY NIGHT: HIGH OPERATIONAL IMPACT. LIKELY RA. SUNDAY: HIGH OPERATIONAL IMPACT. LIKELY RA. && .HYDROLOGY... LAKE EFFECT SNOWBANDS...AND SCATTERED SNOW SHOWERS WILL BE POSSIBLE TODAY AND TONIGHT...WITH MAXIMUM TOTAL LIQUID EQUIVALENT GENERALLY REMAINING UNDER ONE QUARTER OF AN INCH...WHICH WOULD BE ACROSS THE WESTERN ADIRONDACKS. OTHERWISE...THROUGH TONIGHT...TEMPS WILL CONTINUE TO BE BELOW NORMAL AND ICE WILL CONTINUE TO FORM AND THICKEN ON AREA RIVERS...STREAMS AND PARTICULARLY LAKES. A MODERATING TREND IN TEMPS IS LIKELY THU INTO FRI...WITH A FRONTAL BOUNDARY BRINGING SOME SHOWERS TO CLOSE THE WORK WEEK. SOME SNOW MELT IS LIKELY THIS WEEKEND. ALSO...A STORM SYSTEM MOVING ALONG A FRONTAL BOUNDARY MAY BRING SIGNIFICANT PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY WITH EVEN MILDER TEMPS. THIS WILL CONTINUE TO BE MONITORED FOR THE UPCOMING WEEKEND FOR THE POSSIBILITY OF SOME HYDRO ISSUES. 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...LAKE EFFECT SNOW ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM EST THURSDAY FOR NYZ032-033. MA...NONE. VT...NONE. && $$ SYNOPSIS...KL/WASULA NEAR TERM...KL/WASULA SHORT TERM...KL LONG TERM...NAS AVIATION...NAS HYDROLOGY...KL/WASULA
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
607 AM CST WED DEC 18 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 400 AM CST WED DEC 18 2013 AT THIS TIME YESTERDAY MORNING...THE FORECAST AREA WAS 15-30 DEGREES WARMER THAN WE ARE CURRENTLY. THE THERMOMETER WILL GET A WORKOUT TODAY AND EVEN AFTER A CHILLY START...WE SHOULD REBOUND QUITE WELL BY THE AFTERNOON. THE SURFACE RIDGE WILL BE OUT OVER LAKE MICHIGAN BY 15Z AND THE APPROACHING CLIPPER SHOULD BE NEARING THE WESTERN MN BORDER AROUND THE SAME TIME. THE WARM AIR ADVECTION OUT AHEAD OF THE SURFACE LOW THIS MORNING IS IMPRESSIVE AND IT`S THE REASON WE`RE FORECASTING THE WARMEST TEMPERATURES WE`VE SEEN IN OVER TWO WEEKS. THE 18.07Z RAP HAS NEARLY THE ENTIRE FORECAST AREA ABOVE 0C AT 925MB BY 00Z THIS EVENING /6-10C ACROSS MUCH OF WESTERN MN/ AND YOU`RE NOT SEEING THINGS...THAT IS INDEED THE 0C ISOTHERM NEAR THE MN/IA BORDER AT 700 MB. THIS SAME BUBBLE OF WARM AIR WAS OVER WESTERN NE AND SD YESTERDAY AND BROUGHT HIGHS BETWEEN 40-60. NOW THE WARMEST TEMPS WERE IN SNOW FREE AREAS...BUT LOWER 40S WERE OBSERVED EVEN WHERE THERE WAS SNOW ON THE GROUND. WE WILL CERTAINLY BE COOLER THAN WHAT THE PLAINS OBSERVED YESTERDAY...BUT THE DOWNSLOPE AREAS OF THE BUFFALO RIDGE COULD EASILY SEE SOME LOWER 40S...ESPECIALLY IF WE ESTABLISH A SOUTHWEST COMPONENT TO THE WIND BEFORE THE NOON HOUR. THE MIXING WILL NOT BE GREAT TODAY...ESPECIALLY WITH THE MORNING INVERSION AND SNOW COVER. WE SHOULDN`T MIX AS HIGH AS 925MB AND THIS WILL KEEP HIGHS FROM GETTING TOO WARM. WE HOPE THIS LACK OF MIXING DOESN`T MEAN WE`RE MUCH TOO WARM WITH THE TEMPS TODAY - VERIFICATION HAS SHOWN A WARM BIAS LATELY - THOUGH THAT HAS BEEN WITH 15 TO 30 DEGREE DEPARTURES FROM NORMAL. WE LIKE THE 18.00Z NAM MOS IN THAT IT KEPT THE WESTERN FORECAST AREA WARM AND COOLED THE EAST. THERE SHOULD BE A LARGE WEST-EAST TEMPERATURE GRADIENT TODAY /LOWER 40S FAR WEST - MID TO UPPER 20S FAR EAST/. THE TWIN CITIES METRO IS RIGHT IN THE MIDDLE OF THIS GRADIENT. THERE IS VIRTUALLY NO CHANCE FOR PRECIP IN THE SHORT TERM...BUT PATCHY BLOWING SNOW CAN NOT BE COMPLETELY RULED OUT LATE TONIGHT WHEN A PRONOUNCED AREA OF MSLP PRESSURE RISES SLIDES ACROSS MN BEHIND THE CLIPPER SYSTEM. WE SAW BLOWING SNOW YESTERDAY IN WESTERN MN...BUT THAT WAS WITH BL WINDS THAT WERE 5-7 KTS STRONGER. IN ADDITION...THE WARMER TEMPS TODAY SHOULD PROBABLY ACT TO SETTLE THE CURRENT SNOW PACK A BIT. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 400 AM CST WED DEC 18 2013 ARCTIC AIR WILL OOZE IN ON THURSDAY AS A 1035MB HIGH BUILDS SOUTHWARD INTO THE WESTERN HIGH PLAINS. WHILE THIS IS OCCURRING... A SHORT WAVE WILL MOVE EAST FROM THE NORTHERN ROCKIES DURING THE DAY BRINGING A SURGE OF MID LEVEL MOISTURE TO THE REGION. AMPLE UPGLIDE... SATURATION AND ADIABATIC OMEGA ON THE NAM/GFS 290K THETA SURFACES SPREAD INTO WEST CENTRAL MN BY NOON ON THURSDAY AND ACROSS THE CWA BY EVENING. MIXING RATIOS RISE TO BETWEEN 2 AND 3 G/KG. HOWEVER...THE BEST ADIABATIC OMEGA ONLY LASTS FOR ABOUT 6 HOURS. CONTINUED THE TREND OF RAISING POPS WITH LIKELY FOR THURSDAY AFTERNOON IN WEST CENTRAL MN WITH CATEGORICAL IN PLACE FROM SOUTHWEST MN THROUGH THE TWIN CITIES AND ACROSS MUCH OF WEST CENTRAL WI FOR THURSDAY EVENING. THE SNOW THEN TAPERS OFF GRADUALLY OVERNIGHT FROM WEST TO EAST WITH SOME LINGERING LIGHT SNOW FOR SOUTH CENTRAL MN THROUGH WEST CENTRAL WI ON FRIDAY. SNOW AMOUNTS OF 1.5 TO 2 INCHES ARE LIKELY BY DAYBREAK FRIDAY... ESPECIALLY ON AN EAST-WEST AXIS THAT RUNS THROUGH THE SOUTH METRO...WITH A FEW MORE TENTHS OF AN INCH ON FRIDAY TO THE EAST AND SOUTH OF THE METRO. THE HIGH TO OUR WEST WILL BUILD IN FOR SATURDAY WITH A DRY BUT COLD DAY. DIFFERENCES THEN EVOLVE BETWEEN THE ECMWF...GFS AND GEM ON THE LATTER HALF OF THE WEEKEND AS A STORM SYSTEM EXITS THE SOUTH PLAINS. THE ECMWF REMAINS DRY WITH THE NORTHWEST EDGE OF THE PRECIPITATION FROM THIS SOUTHERN SYSTEM STAYING TO OUR SOUTHEAST. THE GEM GOES HOG WILD DEVELOPING A CLOSED H7 LOW OVER US BY SATURDAY NIGHT WITH 3 TO 5 INCHES OF SNOW FOR SATURDAY NIGHT AND SUNDAY. THE GFS IS IN BETWEEN...HAVING TROUBLE SEPARATING THE NORTHERN AND SOUTHERN STREAM ENERGY. COLLABORATION WAS TO FOLLOW MORE OF THE DRY ECMWF SOLUTION AND REDUCE POPS FROM THE CR EXTEND. A SECOND ARCTIC HIGH WILL BUILD IN FROM SUNDAY INTO MONDAY WITH SOME VERY COLD AIR. DROPPED LOWS TO NEAR 15 BELOW FOR PORTIONS OF CENTRAL MN FOR MONDAY MORNING WITH AROUND 5 BELOW IN THE TWIN CITIES AND ZERO IN EAU CLAIRE. THIS MAY NOT BE COLD ENOUGH IF THE ECMWF IS CORRECT WITH IT/S GUIDANCE SUGGESTING LOWERING LOWS ANOTHER 5 TO 10 DEGREES. SOME MODERATION IS EXPECTED BY CHRISTMAS EVE DAY AS THE FLOW ALOFT BECOMES MORE WESTERLY AND THE HIGH DEPARTS TO OUR SOUTHEAST. HOWEVER...ANOTHER SHORT WAVE AND LOW PRESSURE SYSTEM ARE RIDING THE ARCTIC FRONT WITH SOME MORE SNOW POSSIBLE CHRISTMAS EVE AND CHRISTMAS DAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 541 AM CST WED DEC 18 2013 NO SIGNIFICANT AVIATION WEATHER CONCERNS TODAY OR TONIGHT. THERE IS A SYSTEM APPROACHING...SO THE WINDS WILL VEER AROUND 180 DEGREES FROM THE SOUTHEAST WINDS OUT THERE THIS MORNING. SPEEDS WILL REMAIN PRETTY CONSISTENT BETWEEN 8-12 KTS...WITH A BETTER CHANCE FOR GUSTS UP NEAR 20-25 KTS WHEN THE COLD FRONT COMES THROUGH TONIGHT AND THE WINDS ARE CLOSER TO 310 DEGREES. KMSP... TIMING THE VEERING WINDS IS THE BIGGEST CHALLENGE TODAY WITH NO VIS/CIG RESTRICTIONS. GOOD CONFIDENCE IN THE WIND DIRECTIONAL SHIFT IN THE TAF WITHIN 1-2 HOURS AND 10-30 DEGREES. OTHERWISE NO ISSUES WITH SNOW HOLDING OFF UNTIL THURSDAY EVENING. /OUTLOOK FOR KMSP/ THU NIGHT...MVFR CIGS WITH IFR VIS WITH -SN. LIFR VIS POSSIBLE. WINDS N 10-15 KT. FRI...MVFR CIGS WITH LINGERING IFR/-SN POSSIBLE EARLY. WINDS N 10-15 KT. SAT...MAINLY VFR. WINDS S 5 KT BCMG NW. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...CLF LONG TERM...RAH AVIATION...CLF
AREA FORECAST DISCUSSION
NWS ELKO NV
259 AM PST WED DEC 18 2013 .SYNOPSIS...A LOW PRESSURE SYSTEM WILL BRING SNOW TO THE GREAT BASIN TONIGHT AND THURSDAY. SNOW SHOWERS ARE EXPECTED AGAIN OVER THE WEEKEND. ALTHOUGH THERE MAY BE SOME SNOW SHOWERS AROUND...AT THIS TIME NO TRAVEL CONCERNS ARE ANTICIPATED FOR THE WEEK OF CHRISTMAS. && .SHORT TERM...TODAY THROUGH FRIDAY. HIGH PRESSURE TO OUR SOUTH IS BATTLING AN INCOMING SHORTWAVE THIS MORNING. IR IMAGERY SHOWS A LOT OF MID TO HIGH CLOUDINESS SPREADING ACROSS THE SIERRA MOUNTAIN RANGE AND INTO THE GREAT BASIN AS PACIFIC MOISTURE ALOFT ASSOCIATED WITH THE TROUGH TO BE BEGINS STREAMING INTO OREGON AND WASHINGTON STATE. WATER VAPOR IMAGERY REVEALS FEWER CLOUDS ACROSS NORTHWEST NEVADA AT THIS TIME...BETWIXT THE TWO UPPER LEVEL FEATURES. OTHERWISE...PRETTY QUIET THIS MORNING. TEMPERATURES ARE WARMER THAN RECENT NIGHTS AND DEWPOINTS ARE 10 DEGREES OR MORE ALL ACROSS THE BOARD. THE MODELS SEEM TO BE IN VERY GOOD AGREEMENT FOR THE SHORT TERM. WEDNESDAY MORNING. THIS WILL BE A DRY PERIOD. THERE MAY STILL BE SOME POCKETS OF FOG AHEAD OF ANTICIPATED TROUGH DEVELOPMENT...MORE LIKELY IN THE AREA OF WINNEMUCCA WHERE CLOUDINESS IS LESS EVIDENT. WEDNESDAY AFTERNOON THROUGH EARLY WEDNESDAY EVENING. A TROUGH WILL BEGIN TO DEVELOP OVER CANADA AND DROP DOWN. THE TROUGH AXIS WILL ALIGN THROUGH OR/WA/CA BY LATE EVENING. THE RR QUAD REGIONS OF A TWIN JET CORE IS SHOWN TO BEGIN INFILTRATING NORTHERN NEVADA BY THIS EVENING. LIGHT SNOW SHOWERS ARE EXPECTED TO BEGIN OVER CENTRAL NEVADA THIS AFTERNOON AND THEN DEVELOP ACROSS MOST AREAS BY THIS EVENING. HIGH TEMPERATURES WILL RANGE FROM THE MID 30S NORTH TO THE MID 50S SOUTH OF HIGHWAY 50. LATE WEDNESDAY EVENING THROUGH THURSDAY NIGHT. A WINTER STORM WATCH IS IN EFFECT FOR NORTHERN NYE AND WHITE PINE COUNTIES. A TROUGH AXIS WILL TRAVERSE THE GREAT BASIN AS CENTRAL LOW PRESSURE DEEPENS WHILE IT RELOCATES TO THE NORTHERN BAJA REGION. A STRONG AREA OF LOW LEVEL CONVERGENCE WILL CENTER OVER WHITE PINE COUNTY AND MODEL QPF IS SIGNIFICANT OVER NYE COUNTY AND WHITE PINE COUNTY. AT THIS TIME APPEARS THIS SYSTEM COULD PRODUCE 3 TO 5 INCHES OF SNOWFALL TO THE VALLEYS OF CENTRAL NEVADA WITH ELEVATIONS ABOVE 6500 FEET RECEIVING A FOOT OF SNOW. VALLEY AMOUNTS MAY CHANGE SO THE WINTER STORM WATCH WAS NOT ISSUED FOR A SPECIFIC ELEVATION. AN INCH OR TWO OF SNOW IS EXPECTED ELSEWHERE INCLUDING THE ELKO AND SPRING CREEK AREAS. WINDS WILL BE BREEZY ACROSS HUMBOLDT COUNTY AS MEAN LOW PRESSURE DROPS BEHIND THE SIERRAS IN THE AFTERNOON. SHOWERS SHOULD RAPIDLY TAPER OFF AROUND MIDNIGHT. LEFT SOME LOW POPS IN FOR WHITE PINE COUNTY AFTER MIDNIGHT THURSDAY. HIGH TEMPERATURES WILL RANGE FROM THE MID 20S NORTH TO AROUND 40 SOUTH OF HIGHWAY 50. LOW TEMPERATURES WILL BE IN THE 20S WEDNESDAY NIGHT AND IN THE SINGLE DIGITS THURSDAY NIGHT. FRIDAY. A SHORT WAVE RIDGE WILL BEGIN TO RAPIDLY PUSH ACROSS THE GREAT BASIN. A NORTHWEST FLOW ALOFT INDICATES THIS SHALLOW RIDGE WILL BE DIRTY. SO INTRODUCED LOW POPS ACROSS NORTHERN NEVADA. HIGH TEMPERATURES WILL BE IN THE 20S TO AROUND 30 DEGREES. .LONG TERM...FRIDAY NIGHT THROUGH NEXT TUESDAY. THE PERIOD COMMENCES WITH COASTAL RIDGING FROM BRITISH COLUMBIA TO SOUTHERN CALIFORNIA WITH THE TROF AXIS OVER THE ROCKIES...AND THE JET CORE OVER THE SILVER STATE. THE JET PLACEMENT...ALONG WITH THE SPIKE IN PWS SUGGEST SNOW ACCUMULATIONS IN EASTERN HUMBOLDT COUNTY AND PORTIONS OF ELKO COUNTY...WITH THE BEST ACCUMULATIONS IN OROGRAPHICALLY FAVORED NORTH FACING SLOPES. THE VALLEYS OF ELKO AND EASTERN HUMBOLDT COUNTY WILL LIKELY RECEIVE LESS THAN 2 INCHES OF SNOW FRIDAY NIGHT INTO SATURDAY. AS TIME ELAPSES...SHOWERS TAPER OFF ACROSS NORTHEASTERN NEVADA INTO SUNDAY...WITH SOME LINGERING ISOLATED SHOWERS POSSIBLE ACROSS MOUNTAINS. THE NAEFS AND THE GFS ARE BOTH SHOWING NEAR NORMAL TEMPERATURES TO SLIGHTLY ABOVE NORMAL TEMPERATURES BY DAY 7. THE ONLY CONCERN HERE IS THAT THE MODELS MAY BE WARMING IT UP A SKOSH TOO FAST IN THE GREAT BASIN...AS OFTEN...SNOW EVENTS FOLLOWED BY NORTHERLY FLOW RESULT IN COLD TEMPS. INTERESTINGLY...THE RMOP OF THE ENSEMBLE MEAN FORECAST...SHOWS STRONG/HIGH RMOP OVER THE LKN CWA LATE IN THE PERIOD BUT STRUGGLES EARLIER IN THE PERIOD WITH THE NORTHERLY FLOW. && .AVIATION...VFR CONDITIONS ARE EXPECTED AT ALL TAF SITES. && .LKN WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM THIS EVENING THROUGH THURSDAY EVENING FOR NORTHEASTERN NYE COUNTY...NORTHWESTERN NYE COUNTY...WHITE PINE COUNTY. && $$ 92/97/97
AREA FORECAST DISCUSSION
NWS PORTLAND OR
327 AM PST WED DEC 18 2013 .SYNOPSIS...A WEAK FRONT WILL CONTINUE LIGHT RAIN AND DRIZZLE THIS MORNING. A COLD TROUGH WILL BRING A SHOT OF SHOWERS LATER THIS MORNING AND AFTERNOON FOR SW WASHINGTON AND NW OREGON...AND LATE THIS AFTERNOON AND EVENING FOR THE CENTRAL/SOUTH WILLAMETTE VALLEY AND THE CASCADES. SNOW LEVELS WILL DRAMATICALLY DROP TODAY...WITH SNOW ACCUMULATIONS LIKELY FOR THE CASCADE FOOTHILLS AND CASCADES. DO NOT EXPECT MORE THAN A FEW SNOW FLURRIES FOR THE LOW LANDS. THERE WILL BE A BREAK IN PRECIPITATION THURSDAY BEFORE A WARMER SYSTEM BRINGS RAIN AND MOUNTAIN SNOW ON FRI. WILL NEED TO MONITOR THE POTENTIAL FOR A WINTRY MIX AT SOME LOW ELEVATION LOCATIONS FRI MORNING. AN UPPER LEVEL RIDGE WILL SET UP OVER THE NE PAC LATE IN THE WEEK...WITH SEVERAL SYSTEMS PUSHING OVER THE TOP OF THE RIDGE THROUGH EARLY NEXT WEEK. && .SHORT TERM...TODAY THROUGH FRIDAY NIGHT...A WEAK FRONT WILL CONTINUE LIGHT RAIN/DRIZZLE ACROSS THE REGION THIS MORNING...WITH ACCUMULATIONS GENERALLY LESS THAN A TENTH OF AN INCH. THERE WILL BE A BRIEF BREAK IN PRECIPITATION LATE THIS MORNING BEFORE A MORE DYNAMIC DISTURBANCE BRINGS ADDITIONAL RAIN AND MOUNTAIN SNOW THIS AFTERNOON AND EVENING. THIS SECOND BOUT OF PRECIPITATION IS ASSOCIATED WITH A COLD UPPER LEVEL TROUGH THAT IS DROPPING SOUTHWARD FROM THE GULF OF ALASKA. WATER VAPOR IMAGERY SHOWS THIS TROUGH JUST OFFSHORE VICTORIA B.C. EARLY THIS MORNING. THE TROUGH HAS TRACKED SLIGHTLY MORE OVER THE OCEAN THAN THE PREVIOUS MODEL RUNS FORECASTED ALLOWING MORE MOISTURE TO BECOME AVAILABLE THAN PREVIOUSLY THOUGHT. A COLD POOL WITH 500MB TEMPERATURES NEAR -28 CELSIUS WILL MOVE OVER THE AREA THIS EVENING RESULTING IN ENOUGH INSTABILITY AND LIFT TO TAP INTO THIS MOISTURE. THEREFORE HAVE GREATER FORECAST CONFIDENCE IN SHOWERS FOR TONIGHT AND HAVE RAISED POPS. THIS TROUGH WILL MOVE FAIRLY QUICKLY THROUGH THE AREA FROM NW TO SE WITH PRECIPITATION LIMITED TO THE CASCADES AND LANE COUNTY BY MIDNIGHT TONIGHT. SNOW LEVELS IS THE GREATEST FORECAST CHALLENGE WITH THIS SYSTEM AS THEY WILL DROP DRAMATICALLY THROUGHOUT THE DAY. SNOW LEVELS NEAR 6000 FEET EARLY THIS MORNING WILL LOWER TO LESS THAN A 1000 FEET THIS EVENING. THE SHOWERS SHOULD LEAD THE COLDER AIR AND EXPECT ONLY SNOW ACCUMULATIONS FOR THE CASCADES AND CASCADE FOOTHILLS. THE HRRR MODEL WHICH HISTORICALLY HAS HANDLED THESE TYPE OF SHOWERS VERY WELL SHOWS THESE SHOWERS REACHING THE SW WA COAST AROUND 17Z (11 AM) AND THE PORTLAND METRO AREA AROUND 22Z (2 PM)...AND OVER THE CENTRAL WILLAMETTE VALLEY AROUND 4 PM. THE QUICK MOVING NATURE OF THE TROUGH WILL LIMIT RAIN/SNOW ACCUMULATIONS AND EXPECT LESS THAN 0.25 INCH OF RAIN FOR THE NORTHERN LOW LAND AREAS AND LESS THAN 0.15 INCH FOR THE SOUTHERN LOW LAND AREAS. THE CASCADES WILL LIKELY HAVE 1 TO 3 INCHES OF SNOW WITH THE CASCADE FOOTHILLS POSSIBLY MEASURING UP TO 2 INCHES. HIGH PRESSURE WILL BUILD BEHIND THE TROUGH EARLY THURSDAY MORNING. LINGERING SURFACE MOISTURE FROM THE EVENING SHOWERS COMBINED WITH LIGHT WINDS AND CLEARING SKIES SHOULD RESULT IN WIDESPREAD RADIATION FOG EARLY THURSDAY MORNING. TEMPERATURES WILL BE BELOW FREEZING WITH FREEZING FOG POSSIBLY RESULTING IN SLICK DRIVING CONDITIONS FOR THE MORNING COMMUTE. WEAK OFFSHORE WINDS SHOULD DEVELOP THU AFTERNOON AND HELP DISSIPATE THE FOG. THURSDAY WILL BE DRY AND COLD WITH INCREASING CLOUDS AHEAD OF THE NEXT FRONT. THE NEXT MORE ORGANIZED FRONT WILL APPROACH THURSDAY NIGHT. THIS FRONT HAS A LOT MORE MOISTURE WITH IT AS GFS IS FORECASTING MODELED TROPICAL PRECIPITABLE WATER VALUES NEAR AN INCH. THE DIFFERENT FORECAST MODELS VARY ON THE TIMING...AND QPF WITH THIS FRONT WITH THE NAM MODEL BEING THE MOST AGGRESSIVE. HAVE LEANED TOWARDS A BLEND OF THE GFS AND NAM FOR TIMING AND AMOUNT OF PRECIPITATION. THE AVAILABLE MOISTURE...LIFT AND APPARENT SLOW MOVING NATURE OF THIS FRONT PROVIDES GREAT POTENTIAL FOR A DECENT RAINFALL EVENT FRIDAY. SNOW LEVELS SHOULD RAPIDLY WARM AHEAD OF THIS FRONT BUT THERE IS STILL THE POSSIBILITY THAT SOME OF THE PRECIPITATION WILL OVER RUN THE WARMING LEADING TO A BRIEF PERIOD OF LOW ELEVATION SNOW. HOWEVER...SIGNIFICANT IMPACTS APPEAR UNLIKELY...AS THERE WILL LIKELY NOT BE MUCH OF A COLD POOL ON THE EAST SIDE OF THE CASCADES. WILL HAVE A BETTER IDEA OF THE DEPTH OF THE COLD AIR AND WHAT IT WILL TAKE TO ERODE THE COLD AIR AFTER THE WEDNESDAY EVENT PLAYS OUT. HARTLEY .LONG TERM...SATURDAY THROUGH TUESDAY...MADE NO CHANGES AND PREVIOUS DISCUSSION FOLLOWS...AT THIS TIME...THE EXTENDED PORTION OF THE FCST APPEARS TO ON THE MILD AND MOIST SIDE. AN UPPER LEVEL RIDGE OVER THE NE PAC IS MODELED TO STEER SEVERAL BATCHES OF MOISTURE SOUTH INTO THE PAC NW OVER THE WEEKEND AND EARLY NEXT WEEK. THIS WILL LIKELY LEAD TO PERIODS OF LIGHT RAINFALL. CONFIDENCE ON THE TIMING OF THESE SYSTEMS IS NOT HIGH AT THIS TIME. DO NOT CURRENTLY EXPECT ANY SIGNIFICANT WEATHER IMPACTS TO HOLIDAY TRAVEL AHEAD OF CHRISTMAS. PYLE && .AVIATION...IFR AND LIFR CIGS AND OCCASIONAL VIS CONTINUE THIS MORNING THROUGH ABOUT 18Z-20Z. EXPECT MVFR CIGS AROUND 2500-3500 FT WITH DRIZZLE/LIGHT RAIN WHEN THE PRIMARY FRONT MOVES THROUGH LATER THIS AFTERNOON. CIGS LIFT TO LOW END MVFR TONIGHT...WITH A THREAT FOR LIFR FOG EARLY THURSDAY MORNING. KPDX AND APPROACHES...IFR CIGS BUT WITH VFR VIS WILL CONTINUE THROUGH ABOUT 18Z THIS MORNING WHEN THE NEXT FRONT APPROACHES. CIGS LIFT TO MVFR/LOW END VFR BEHIND THE FRONT...BUT IFR/LIFR FOG MAY REDEVELOP AROUND 12Z THURSDAY. /27 && .MARINE...AN APPROACHING COLD FRONT WILL BRING GUSTY NW POST FRONTAL WINDS UP TO 25 KT AND SEAS ABOVE 10 FT ACROSS THE WATERS THIS AFTERNOON. THE SMALL CRAFT ADVISORY FOR BOTH WINDS AND SEAS REMAINS IN EFFECT THROUGH EARLY THURSDAY MORNING. SEAS REMAIN AROUND 7 OR 8 FT THIS MORNING BEFORE RISING TO 10 TO 11 FT AS WINDS PICK UP LATER TODAY. SEAS AND WINDS EASE BACK ON THU AND THU NIGHT. BUT ANOTHER FRONT WILL BRING ANOTHER ROUND OF GUSTY WINDS AND SEAS FOR LATER FRI AND SAT. ROCKEY. && .PQR WATCHES/WARNINGS/ADVISORIES... OR...NONE. WA...NONE. PZ...SMALL CRAFT ADVISORY FOR WINDS FROM NOON TODAY TO NOON PST THURSDAY FOR COASTAL WATERS FROM CAPE SHOALWATER TO FLORENCE OUT 60 NM. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM NOON TODAY TO NOON PST THURSDAY FOR COASTAL WATERS FROM CAPE SHOALWATER TO FLORENCE OUT 60 NM. SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 3 PM THIS AFTERNOON TO 7 PM PST THIS EVENING. && $$ MORE WEATHER INFORMATION ONLINE AT.. HTTP://WEATHER.GOV/PORTLAND INTERACT WITH US VIA SOCIAL MEDIA WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV WWW.TWITTER.COM/NWSPORTLAND THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
634 AM EST WED DEC 18 2013 .SYNOPSIS... UPPER LVL TROUGH OVER THE NORTHEAST CONUS THIS MORNING WILL LIFT OUT...GIVING WAY TO A BUILDING RIDGE OFF OF THE E COAST FOR THE REST OF THE WEEK. AT THE SFC...A QUASI-STATIONARY FRONT WILL REMAIN DRAPED ACROSS THE EASTERN GRT LKS LATE THIS WEEK AND THROUGH THE WEEKEND. THIS BOUNDARY WILL FINALLY PUSH SOUTHEAST THRU PA LATE SUNDAY OR EARLY MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WATER VAPOR LOOP SHOWS UPPER TROUGH AXIS PASSING EAST OF PA AT 11Z. IN IT/S WAKE...A COLD WESTERLY FLOW CROSSING LK ERIE SHOULD SUPPORT A SINGLE LE SNOW BAND JUST NORTH OF THE PA BORDER TODAY...AS INDICATED BY LATEST NAM AND RAP OUTPUT. ELSEWHERE...LOW LVL MOISTURE TRAPPED BENEATH SUBSIDENCE INVERSION AND FORCED TO ASCEND THE ALLEGHENIES WILL PRODUCE FLURRIES/SCT -SHSN ACROSS THE W MTNS. ACCUMULATIONS SHOULD BE MAINLY JUST A DUSTING. HOWEVER...PERHAPS UP TO AN INCH OVR NW WARREN CO...DUE TO FRINGE EFFECTS OF LE BAND. TIGHTENING PRESSURE GRADIENT BTWN HIGH PRES OVR THE SERN STATES AND THE RAPIDLY INTENSIFYING LOW E OF NEW ENG WILL CREATE A BRISK WEST WIND TODAY ACROSS ALL OF CENTRAL PA WITH GUSTS BTWN 15-25KTS PER LATEST BUFKIT SOUNDINGS /HIGHEST ACROSS THE LAURELS AND SC MTNS/. MIXING TO THE ENS MEAN 925MB TEMPS SUPPORTS HIGH TEMPS SEVERAL DEG BLW NORMAL...RANGING FROM THE M20S W MTNS...TO THE M30S ACROSS THE LOWER SUSQ VALLEY WHERE DOWNSLOPING NW FLOW SHOULD YIELD PTSUNNY SKIES. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... FALLING INVERSION HGTS WITH ARRIVAL OF SFC RIDGE SHOULD BRING AN END TO ANY LINGERING FLURRIES ACROSS THE NW MTNS BY THIS EVENING. LIGHT WINDS AND A MCLEAR SKY SHOULD ALLOW TEMPS FALL FAIRLY QUICKLY INTO THE UTEENS/L20S THIS EVENING. HOWEVER...INCREASING CIRRUS AND DEVELOPING SWRLY BREEZE AS SFC RIDGE PASSES EAST OF THE AREA SHOULD CAUSE TEMPS TO LEVEL OFF OR EVEN RISE A BIT LATE TONIGHT. DEEP SW FLOW INDICATED BY THURSDAY...AS RIDGE BUILDS OFF THE EAST COAST AND TROUGH DIGS OVR THE WESTERN CONUS. THIS SW FLOW WILL ADVECT MUCH MILDER AIR INTO PA WITH READINGS LIKELY APPROACHING 40F IN THE NORTH AND SURGING WELL INTO THE 40S ACROSS THE SOUTHERN COUNTIES. LL JET AND ASSOC PLUME OF HIGH PWATS AT INTERFACE OF EASTERN RIDGE/WESTERN TROUGH WILL BE FOCUSED ACROSS THE EASTERN GRT LKS BUT WILL LIKELY PRODUCE MCLDY SKIES ACROSS NORTHERN PA ON THURSDAY...WHILE MSUNNY LIKELY IN THE SOUTH. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... LITTLE SPREAD AMONGST MED RANGE MDLS THRU THE UPCOMING WEEKEND...ALL OF WHICH SHOW AN ANOMALOUS TROUGH CENTERED OVR THE W PLAINS AND ANOMALOUS RIDGE OFF OF THE SE COAST. AT INTERFACE OF THESE SYSTEMS...A DEEP SOUTHERLY FLOW AND ASSOC PLUME OF HIGH PWATS WILL EXTEND ALONG QUASI-STATIONARY FRONT DRAPED FROM THE WESTERN GULF OF MEX TO THE E GRT LKS. WAVES OF LOW PRESSURE RIDING WEST OF PA WILL BRING THE CHC OF RAIN TO MAINLY THE NW COUNTIES AND KEEP THE ENTIRE CWA ON THE WARM SIDE OF THE BNDRY. BY SUNDAY...THE STRONGEST OF THE WAVES IS PROGGED TO TRACK ACROSS NW PA. GEFS PWATS ON THE ORDER OF 3-4SD ABV NORMAL WILL ACCOMPANY THE ASSOC LL JET AND WILL LIKELY PRODUCE HVY RAIN JUST WEST OF LOW TRACK. LATEST MDL BLEND INDICATES THIS HVY RAIN THREAT WILL BE JUST WEST OF OUR AREA. IN THE WARM SECTOR...NEAR RECORD HIGH TEMPS ARE POSSIBLE SUNDAY...AS GEFS MEAN 925/850 TEMPS SURGE TO NR 2SD ABV NORMAL. 00Z ECMWF MOS NUMBERS ALREADY INDICATING NR RECORD TEMPS IN THE L/M60S ACROSS THE EASTERN HALF OF THE STATE. TRAILING COLD FRONT SHOULD BRING A RETURN TO MORE DECEMBER-LIKE TEMPS BY EARLY NEXT WEEK. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... WIDESPREAD FOG WITH MVFR VSBYS AND CIGS...AND A FEW LIGHT SNOW SHOWERS WILL CONTINUE THROUGH THE MID MORNING HOURS. CONDITIONS SHOULD IMPROVE LATER THIS MORNING...AFTER 14-15Z AS HIGH PRESSURE BUILDS INTO REGION AND WINDS INCREASE AND PROVIDE SOME MIXING OF THE LOWER LEVELS. WNW WINDS WILL BECOME BRISK LATER THIS MORNING...AS THE PRESSURE GRADIENT TIGHTENS BETWEEN DEEPENING LOW PRES OVER THE CANADIAN MARITIMES AND HIGH PRES OVER THE SERN US. EASTERN TAF SITES SHOULD QUICKLY IMPROVE TO VFR CONDS IN DOWNSLOPING FLOW. JST AND BFD WILL TAKE A BIT LONGER...BUT WILL EVENTUALLY IMPROVE TO VFR AS WELL. AFTER A QUIET WEATHER ON THURS...A DEVELOPING MOIST SOUTHERLY FLOW WILL TURN THINGS UNSETTLED FRI INTO THIS WEEKEND. OUTLOOK... THU...GENERALLY VFR. FRI-SUN...REDUCED CONDS LKLY AS ABUNDANT MOISTURE AND MILDER AIR STREAMS NEWD AHEAD OF A SLOW-MOVING FRONTAL SYSTEM. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD NEAR TERM...FITZGERALD SHORT TERM...FITZGERALD LONG TERM...FITZGERALD AVIATION...GARTNER/EVANEGO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
617 AM EST WED DEC 18 2013 .SYNOPSIS... UPPER LVL TROUGH OVER THE NORTHEAST CONUS THIS MORNING WILL LIFT OUT...GIVING WAY TO A BUILDING RIDGE OFF OF THE E COAST FOR THE REST OF THE WEEK. AT THE SFC...A QUASI-STATIONARY FRONT WILL REMAIN DRAPED ACROSS THE EASTERN GRT LKS LATE THIS WEEK AND THROUGH THE WEEKEND. THIS BOUNDARY WILL FINALLY PUSH SOUTHEAST THRU PA LATE SUNDAY OR EARLY MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WATER VAPOR LOOP SHOWS UPPER TROUGH AXIS PASSING EAST OF PA AT 10Z. IN IT/S WAKE...A COLD WESTERLY FLOW CROSSING LK ERIE SHOULD SUPPORT A SINGLE LE SNOW BAND JUST NORTH OF THE PA BORDER TODAY...AS INDICATED BY LATEST NAM AND RAP OUTPUT. ELSEWHERE...LOW LVL MOISTURE TRAPPED BENEATH SUBSIDENCE INVERSION AND FORCED TO ASCEND THE ALLEGHENIES WILL PRODUCE FLURRIES/SCT -SHSN ACROSS THE W MTNS. ACCUMULATIONS SHOULD BE MAINLY JUST A DUSTING. HOWEVER...PERHAPS UP TO AN INCH OVR NW WARREN CO...DUE TO FRINGE EFFECTS OF LE BAND. TIGHTENING PRESSURE GRADIENT BTWN HIGH PRES OVR THE SERN STATES AND THE RAPIDLY INTENSIFYING LOW E OF NEW ENG WILL CREATE A BRISK WEST WIND TODAY ACROSS ALL OF CENTRAL PA WITH GUSTS BTWN 15-25KTS PER LATEST BUFKIT SOUNDINGS /HIGHEST ACROSS THE LAURELS AND SC MTNS/. MIXING TO THE ENS MEAN 925MB TEMPS SUPPORTS HIGH TEMPS SEVERAL DEG BLW NORMAL...RANGING FROM THE M20S W MTNS...TO THE M30S ACROSS THE LOWER SUSQ VALLEY WHERE DOWNSLOPING NW FLOW SHOULD YIELD PTSUNNY SKIES. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... FALLING INVERSION HGTS WITH ARRIVAL OF SFC RIDGE SHOULD BRING AN END TO ANY LINGERING FLURRIES ACROSS THE NW MTNS BY THIS EVENING. LIGHT WINDS AND A MCLEAR SKY SHOULD ALLOW TEMPS FALL FAIRLY QUICKLY INTO THE UTEENS/L20S THIS EVENING. HOWEVER...INCREASING CIRRUS AND DEVELOPING SWRLY BREEZE AS SFC RIDGE PASSES EAST OF THE AREA SHOULD CAUSE TEMPS TO LEVEL OFF OR EVEN RISE A BIT LATE TONIGHT. DEEP SW FLOW INDICATED BY THURSDAY...AS RIDGE BUILDS OFF THE EAST COAST AND TROUGH DIGS OVR THE WESTERN CONUS. THIS SW FLOW WILL ADVECT MUCH MILDER AIR INTO PA WITH READINGS LIKELY APPROACHING 40F IN THE NORTH AND SURGING WELL INTO THE 40S ACROSS THE SOUTHERN COUNTIES. LL JET AND ASSOC PLUME OF HIGH PWATS AT INTERFACE OF EASTERN RIDGE/WESTERN TROUGH WILL BE FOCUSED ACROSS THE EASTERN GRT LKS BUT WILL LIKELY PRODUCE MCLDY SKIES ACROSS NORTHERN PA ON THURSDAY...WHILE MSUNNY LIKELY IN THE SOUTH. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... LITTLE SPREAD AMONGST MED RANGE MDLS THRU THE UPCOMING WEEKEND...ALL OF WHICH SHOW AN ANOMALOUS TROUGH CENTERED OVR THE W PLAINS AND ANOMALOUS RIDGE OFF OF THE SE COAST. AT INTERFACE OF THESE SYSTEMS...A DEEP SOUTHERLY FLOW AND ASSOC PLUME OF HIGH PWATS WILL EXTEND ALONG QUASI-STATIONARY FRONT DRAPED FROM THE WESTERN GULF OF MEX TO THE E GRT LKS. WAVES OF LOW PRESSURE RIDING WEST OF PA WILL BRING THE CHC OF RAIN TO MAINLY THE NW COUNTIES AND KEEP THE ENTIRE CWA ON THE WARM SIDE OF THE BNDRY. BY SUNDAY...THE STRONGEST OF THE WAVES IS PROGGED TO TRACK ACROSS NW PA. GEFS PWATS ON THE ORDER OF 3-4SD ABV NORMAL WILL ACCOMPANY THE ASSOC LL JET AND WILL LIKELY PRODUCE HVY RAIN JUST WEST OF LOW TRACK. LATEST MDL BLEND INDICATES THIS HVY RAIN THREAT WILL BE JUST WEST OF OUR AREA. IN THE WARM SECTOR...NEAR RECORD HIGH TEMPS ARE POSSIBLE SUNDAY...AS GEFS MEAN 925/850 TEMPS SURGE TO NR 2SD ABV NORMAL. 00Z ECMWF MOS NUMBERS ALREADY INDICATING NR RECORD TEMPS IN THE L/M60S ACROSS THE EASTERN HALF OF THE STATE. TRAILING COLD FRONT SHOULD BRING A RETURN TO MORE DECEMBER-LIKE TEMPS BY EARLY NEXT WEEK. && .AVIATION /11Z WEDNESDAY THROUGH SUNDAY/... WIDESPREAD FOG WITH MVFR VSBYS AND CIGS...AND A FEW LIGHT SNOW SHOWERS WILL CONTINUE THROUGH THE MID MORNING HOURS. CONDITIONS SHOULD IMPROVE LATER THIS MORNING...AFTER 14-15Z AS HIGH PRESSURE BUILDS INTO REGION AND WINDS INCREASE AND PROVIDE SOME MIXING OF THE LOWER LEVELS. WNW WINDS WILL BECOME BRISK LATER THIS MORNING...AS THE PRESSURE GRADIENT TIGHTENS BETWEEN DEEPENING LOW PRES OVER THE CANADIAN MARITIMES AND HIGH PRES OVER THE SERN US. EASTERN TAF SITES SHOULD QUICKLY IMPROVE TO VFR CONDS IN DOWNSLOPING FLOW. JST AND BFD WILL TAKE A BIT LONGER...BUT WILL EVENTUALLY IMPROVE TO VFR AS WELL. AFTER A QUIET WEATHER ON THURS...A DEVELOPING MOIST SOUTHERLY FLOW WILL TURN THINGS UNSETTLED FRI INTO THIS WEEKEND. OUTLOOK... THU...GENERALLY VFR. FRI-SUN...REDUCED CONDS LKLY AS ABUNDANT MOISTURE AND MILDER AIR STREAMS NEWD AHEAD OF A SLOW-MOVING FRONTAL SYSTEM. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD NEAR TERM...FITZGERALD SHORT TERM...FITZGERALD LONG TERM...FITZGERALD AVIATION...GARTNER/EVANEGO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
547 AM EST WED DEC 18 2013 .SYNOPSIS... UPPER LVL TROUGH OVER THE NORTHEAST CONUS THIS MORNING WILL LIFT OUT...GIVING WAY TO A BUILDING RIDGE OFF OF THE E COAST FOR THE REST OF THE WEEK. AT THE SFC...A QUASI-STATIONARY FRONT WILL REMAIN DRAPED ACROSS THE EASTERN GRT LKS LATE THIS WEEK AND THROUGH THE WEEKEND. THIS BOUNDARY WILL FINALLY PUSH SOUTHEAST THRU PA LATE SUNDAY OR EARLY MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WATER VAPOR LOOP SHOWS UPPER TROUGH AXIS PASSING EAST OF PA AT 10Z. IN IT/S WAKE...A COLD WESTERLY FLOW CROSSING LK ERIE SHOULD SUPPORT A SINGLE LE SNOW BAND JUST NORTH OF THE PA BORDER TODAY...AS INDICATED BY LATEST NAM AND RAP OUTPUT. ELSEWHERE...LOW LVL MOISTURE TRAPPED BENEATH SUBSIDENCE INVERSION AND FORCED TO ASCEND THE ALLEGHENIES WILL PRODUCE FLURRIES/SCT -SHSN ACROSS THE W MTNS. ACCUMULATIONS SHOULD BE MAINLY JUST A DUSTING. HOWEVER...PERHAPS UP TO AN INCH OVR NW WARREN CO...DUE TO FRINGE EFFECTS OF LE BAND. TIGHTENING PRESSURE GRADIENT BTWN HIGH PRES OVR THE SERN STATES AND THE RAPIDLY INTENSIFYING LOW E OF NEW ENG WILL CREATE A BRISK WEST WIND TODAY ACROSS ALL OF CENTRAL PA WITH GUSTS BTWN 15-25KTS PER LATEST BUFKIT SOUNDINGS /HIGHEST ACROSS THE LAURELS AND SC MTNS/. MIXING TO THE ENS MEAN 925MB TEMPS SUPPORTS HIGH TEMPS SEVERAL DEG BLW NORMAL...RANGING FROM THE M20S W MTNS...TO THE M30S ACROSS THE LOWER SUSQ VALLEY WHERE DOWNSLOPING NW FLOW SHOULD YIELD PTSUNNY SKIES. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... FALLING INVERSION HGTS WITH ARRIVAL OF SFC RIDGE SHOULD BRING AN END TO ANY LINGERING FLURRIES ACROSS THE NW MTNS BY THIS EVENING. LIGHT WINDS AND A MCLEAR SKY SHOULD ALLOW TEMPS FALL FAIRLY QUICKLY INTO THE UTEENS/L20S THIS EVENING. HOWEVER...INCREASING CIRRUS AND DEVELOPING SWRLY BREEZE AS SFC RIDGE PASSES EAST OF THE AREA SHOULD CAUSE TEMPS TO LEVEL OFF OR EVEN RISE A BIT LATE TONIGHT. DEEP SW FLOW INDICATED BY THURSDAY...AS RIDGE BUILDS OFF THE EAST COAST AND TROUGH DIGS OVR THE WESTERN CONUS. THIS SW FLOW WILL ADVECT MUCH MILDER AIR INTO PA WITH READINGS LIKELY APPROACHING 40F IN THE NORTH AND SURGING WELL INTO THE 40S ACROSS THE SOUTHERN COUNTIES. LL JET AND ASSOC PLUME OF HIGH PWATS AT INTERFACE OF EASTERN RIDGE/WESTERN TROUGH WILL BE FOCUSED ACROSS THE EASTERN GRT LKS BUT WILL LIKELY PRODUCE MCLDY SKIES ACROSS NORTHERN PA ON THURSDAY...WHILE MSUNNY LIKELY IN THE SOUTH. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... LITTLE SPREAD AMONGST MED RANGE MDLS THRU THE UPCOMING WEEKEND...ALL OF WHICH SHOW AN ANOMALOUS TROUGH CENTERED OVR THE W PLAINS AND ANOMALOUS RIDGE OFF OF THE SE COAST. AT INTERFACE OF THESE SYSTEMS...A DEEP SOUTHERLY FLOW AND ASSOC PLUME OF HIGH PWATS WILL EXTEND ALONG QUASI-STATIONARY FRONT DRAPED FROM THE WESTERN GULF OF MEX TO THE E GRT LKS. WAVES OF LOW PRESSURE RIDING WEST OF PA WILL BRING THE CHC OF RAIN TO MAINLY THE NW COUNTIES AND KEEP THE ENTIRE CWA ON THE WARM SIDE OF THE BNDRY. BY SUNDAY...THE STRONGEST OF THE WAVES IS PROGGED TO TRACK ACROSS NW PA. GEFS PWATS ON THE ORDER OF 3-4SD ABV NORMAL WILL ACCOMPANY THE ASSOC LL JET AND WILL LIKELY PRODUCE HVY RAIN JUST WEST OF LOW TRACK. LATEST MDL BLEND INDICATES THIS HVY RAIN THREAT WILL BE JUST WEST OF OUR AREA. IN THE WARM SECTOR...NEAR RECORD HIGH TEMPS ARE POSSIBLE SUNDAY...AS GEFS MEAN 925/850 TEMPS SURGE TO NR 2SD ABV NORMAL. 00Z ECMWF MOS NUMBERS ALREADY INDICATING NR RECORD TEMPS IN THE L/M60S ACROSS THE EASTERN HALF OF THE STATE. TRAILING COLD FRONT SHOULD BRING A RETURN TO MORE DECEMBER-LIKE TEMPS BY EARLY NEXT WEEK. && .AVIATION /10Z WEDNESDAY THROUGH SUNDAY/... A WEAK PRESSURE GRADIENT ACROSS CENTRAL AND EASTERN PENN WILL MAINTAIN LIGHT WINDS AND MVFR VSBYS IN FOG/HAZE INTO THE OVERNIGHT...BEFORE A LIGHT WESTERLY WIND AND SOME DRIER AIR SHOULD ALLOW FOR SOME IMPROVEMENT LATE. IPT AND LNS HAVE BEEN FLIRTING WITH IFR VSBYS...WHICH MAY CONTINUE FOR THE NEXT FEW HOURS. ACROSS THE WESTERN TAF SITES /JST AND BFD/...ANOTHER DISTURBANCE WILL BRING SCT SHSN INTO THE AREA OVERNIGHT. AN UPSLOPING WNW FLOW WILL DEVELOP AS WELL...KNOCKING CIGS/VSBYS DOWN WITH CONTINUED SHSN ACTIVITY. WNW WINDS WILL BECOME BRISK ON WEDNESDAY...AS THE PRESSURE GRADIENT TIGHTENS BETWEEN DEEPENING LOW PRES OVER THE CANADIAN MARITIMES AND HIGH PRES OVER THE SERN US. EASTERN TAF SITES SHOULD IMPROVE TO GENERALLY VFR CONDS ON WED...IN THE DOWNSLOPING WNW FLOW. EVEN JST AND BFD WILL EVENTUALLY SEE SOME IMPROVEMENT /TO AT LEAST MVFR/ AS THE DAY PROGRESSES. AFTER A QUIET THURS...A DEVELOPING MOIST SOUTHERLY FLOW WILL TURN THINGS UNSETTLED FRI INTO THIS WEEKEND. OUTLOOK... WED...SHSN AND REDUCED CIGS/VSBYS EARLY ACROSS THE WESTERN MTNS /BFD AND JST/...WITH GRADUAL IMPROVEMENT. BECOMING VFR ELSEWHERE. THU...GENERALLY VFR. FRI-SUN...REDUCED CONDS LKLY AS ABUNDANT MOISTURE AND MILDER AIR STREAMS NEWD AHEAD OF A SLOW-MOVING FRONTAL SYSTEM. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD NEAR TERM...FITZGERALD SHORT TERM...FITZGERALD LONG TERM...FITZGERALD AVIATION...EVANEGO
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
530 AM CST WED DEC 18 2013 .UPDATE... SEE UPDATED AVIATIION DISCUSSION BELOW. && .PREVIOUS DISCUSSION... .SHORT TERM...TODAY THROUGH FRIDAY VERY GOOD AGREEMENT AMONGST THE MODELS WITH THE UPPER LEVEL AND SURFACE FEATURES TO AFFECT OUR REGION THROUGH FRIDAY. FOR TODAY...A SURFACE LOW PRESSURE AREA IN CANADA THIS MORNING WILL DESCEND SOUTHEAST ALONG A STRONG NORTHWEST TO SOUTHEAST FRONTAL ZONE BISECTING THE UPPER MIDWEST. TEMPERATURES THROUGH THIS FRONTAL ZONE EARLY THIS MORNING RANGED FROM THE TEENS BELOW ZERO IN NORTHEAST MINNESOTA TO 45 TO 50 DEGREES IN SOUTHWEST SOUTH DAKOTA. THE MUCH COLDER AIR THAT WILL AFFECT OUR REGION IS SITUATED BEHIND THIS SURFACE LOW PRESSURE AREA IN CANADA EARLY THIS MORNING. UNTIL THIS MOVES IN TONIGHT...THE CWA WILL EXPERIENCE ANOTHER ABOVE NORMAL TEMPERATURE/MILD DAY AS THE WARM FRONT OUT WEST PUSHES EAST IN ADVANCE OF THE SURFACE LOW. SOUTH TO SOUTHEAST WINDS THIS MORNING WILL TURN WEST AND NORTHWEST THROUGH THE DAY. THE ISSUE TODAY WILL BE HOW MUCH OF THE WARMER AIR ALOFT WILL BE REALIZED AT THE SURFACE AS THERE WILL BE A STRONG INVERSION ACROSS THE CWA. DUE TO THIS INVERSION...THE STRONGER WEST TO NORTHWEST WINDS OFF THE SURFACE WILL HAVE A HARD TIME MIXING DOWN. THE SNOW COVER HAS ALSO DIMINISHED SOME ACROSS THE CWA OVER THE LAST FEW DAYS RANGING GENERALLY FROM 1 TO 4 INCHES. HIGH RH ON TSCTS AND CLOUDS ON SATELLITE SHOWS THAT THE AREA SHOULD BE COVERED BY AN EXPANSIVE DECK OF MID AND HIGH LEVEL CLOUDS THROUGH THE DAY...INHIBITING SURFACE HEATING. TEMPERATURES EARLY THIS MORNING ACROSS THE CWA WERE ALREADY IN THE UPPER TEENS TO MID 20S WITH 50S OFF THE SURFACE ACROSS THE CWA. THUS...DO EXPECT THE REGION TO WARM INTO THE MID 30S TO THE MID 40S WITH SOME UPPER 40S FAR SOUTHWEST IN THE CWA BY LATE THIS AFTERNOON MELTING MORE SNOW...ESPECIALLY SOUTHWEST IN THE CWA. AS THE SURFACE LOW PRESSURE AREA PASSES BY...A STRONG ARCTIC FRONT WILL DROP ACROSS THE REGION TONIGHT. THIS WILL BRING BLUSTERY NORTH TO NORTHEAST WINDS ALONG WITH A BIG FALL IN TEMPERATURES TONIGHT. EXPECT LOWS TONIGHT IN THE SINGLE DIGITS AND LOWER TEENS ACROSS THE CWA. THURSDAY WILL REMAIN VERY COLD WITH LITTLE IF ANY RISE IN TEMPERATURES THROUGH THE DAY. THE OTHER ISSUE FOR LATER TONIGHT THROUGH THURSDAY EVENING WILL BE THE LIGHT SNOW DEVELOPING. SHORT WAVE ENERGY DROPPING IN FROM THE NORTHWEST ALONG WITH THE WARM AIR RIDING OVER THE ARCTIC AIR AND RR UPPER LEVEL JET SUPPORT WILL BRING LIGHT SNOW INTO THE NORTHWEST CWA LATER TONIGHT. THIS LIGHT SNOW WILL DEVELOP SOUTH AND THEN EAST INTO THURSDAY. THE BEST CHANCES OF LIGHT SNOW AND DECENT ACCUMULATIONS WILL REMAIN FROM MOBRIDGE TO PIERRE AND THEN EAST OVER TO MILLER AND TO WATERTOWN WITH 1 TO 3 INCHES POSSIBLE. WITH DRIER ARCTIC AIR PUSHING IN ALONG WITH LESS LIFT...THE SNOW AND ACCUMULATIONS ARE EXPECTED TO BE LIGHTER FROM ABERDEEN TO SISSETON TO WHEATON MAYBE AN INCH OR LESS. THE OTHER ISSUE WILL BE THE BLUSTERY NORTH TO NORTHEAST WINDS DEVELOPING WITH THE STRONG CAA AND A TIGHTENING SURFACE PRESSURE GRADIENT. COULD SEE WINDS OF 20 TO 30 MPH DEVELOPING WHICH WILL BRING SOME BLOWING SNOW AND FALLING WIND CHILLS. THE LIGHT SNOW WILL MOVE OUT...WINDS WILL FALL OFF QUICKLY AND SKIES WILL CLEAR THURSDAY NIGHT AS SURFACE HIGH PRESSURE SETTLES OVER THE REGION. WITH THE NEW SNOW COVER...LIGHT WINDS AND CLEAR SKIES...TEMPERATURES WILL FALL TO BELOW ZERO ACROSS ALL OF THE CWA WITH MAYBE SOME TEENS BELOW ZERO IF CONDITIONS ARE RIGHT. WITH WINDS TURNING SOUTH BEHIND THE EXITING SURFACE HIGH PRESSURE AREA ON FRIDAY...TEMPERATURES WILL HAVE A LONG WAY TO GO WITH WEAK SURFACE WAA. WITH THE NEW SNOW COVER AND MOSTLY SUNNY SKIES...TEMPERATURES WILL STRUGGLE TO MAKE IT TO 10 DEGREES IN THE EASTERN CWA WITH 15 TO AROUND 20 DEGREES OUT WEST. .LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY THE PERIOD OPENS WITH AN UPPER TROUGH SITTING OVER THE REGION. THE UPPER FLOW FLATTENS SLIGHTLY ON MONDAY BEFORE ANOTHER TROF SHIFTS IN ON TUESDAY. MONDAY NIGHT/TUESDAY MORNING A COLD FRONT MOVES THROUGH THE PLAINS. EARLY TUESDAY THERE MAY BE ENOUGH MIXING AHEAD OF THE FRONT TO POP THE TEMPERATURES UP INTO THE 20S...BUT IF THE GFS TIMING IS CORRECT TEMPS WILL THEN FALL THROUGH THE DAY. THE ECMWF IS A LITTLE SLOWER AND WOULD GIVE SD A SLIGHTLY LONGER REPRIEVE FROM THE ANTICIPATED WELL BELOW NORMAL TEMPS FORECAST FOR THE EXTENDED. THERE ARE NO WELL DEFINED CHANCES OF PRECIP DURING THE EXTENDED. SOME CAA SHORTWAVE SNOW SHOWERS ARE POSSIBLE AT VARIOUS TIMES BUT FORECASTER CONFIDENCE WOULD BE VERY LOW IN TRYING TO PIN DOWN ANY EXACT TIMING OR LOCATION. THEREFORE STUCK WITH ALLBLEND AND ITS MOSTLY DRY CONSENSUS. && .AVIATION... 12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS VFR CONDITIONS WILL PREVAIL ACROSS THE AREA THROUGH THIS EVENING. AN ARCTIC FRONT WILL BEGIN TO PUSH INTO THE REGION THIS EVENING. WINDS WILL SHIFT TO THE NORTH AND INCREASE TO 15 TO 25 KTS. AROUND MIDNIGHT CIGS WILL BEGIN TO LOWER TO MVFR. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...WISE SHORT TERM...MOHR LONG TERM...WISE AVIATION...WISE WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1213 PM MST WED DEC 18 2013 .UPDATE... ISSUED AT 1210 PM MST WED DEC 18 2013 DENSE FOG ADVISORY FOR THE LOWER PORTIONS OF THE COLORADO RIVER VALLEY WAS CANCELLED BY 1030. ATTENTION TURNS TO POTENTIAL FOR FREEZING RAIN IN THE VALLEYS TONIGHT. INVERSIONS ARE BEING MODIFIED SOMEWHAT TODAY WITH GUSTY WINDS AT 700MB CREATING SOME TURBULENCE MIXING AT THE TOPS OF THE INVERSION. THE UINTAH AND GUNNISON BASINS WILL LIKELY STAY TRAPPED WHILE THE OTHER VALLEYS WILL SEE SOME EROSION ALONG THE EDGES. TONIGHT...MOISTURE INCREASES IN MILD WARM ADVECTION. MODEL TIMING IS CONSISTENT WITH THE RAP 17Z SUPPORTING THE 12Z NAM FOR QPF SPREADING INTO NE UT AROUND 03Z AND INTO WESTERN CO AROUND 06Z. THE BEST CHANCE FOR VALLEY PRECIP IS 09-15Z EARLY THURSDAY MORNING FOR THE NORTHERN AND CENTRAL VALLEYS. THE NAM IS THE WET OUTLIER OVERNIGHT. FORECAST PROFILES SHOW AN ABOVE FREEZING LAYER TO 8KFT ABOVE THE GRAND VALLEY BUT WITH SURFACE TEMPERATURES FORECASTED TO STAY IN THE UPPER 20S OVERNIGHT. THE POTENTIAL FOR FREEZING RAIN IS STILL IN PLACE TONIGHT FOR THE NORTHERN AND CENTRAL VALLEYS SO WE ARE CONSIDERING AN ADVISORY. OTHERWISE COLD ADVECTION BEGINS EARLY THURSDAY MORNING WITH SNOW LEVELS AROUND 7500FT NORTH THROUGH THE DAY. THE ASSOCIATED COOL FRONT WITH THE ELONGATED TROUGH NOW IS PROGGED TO STAY NORTH OF THE FORECAST AREA THROUGH THURSDAY THEN PUSH INTO NE UT-NW CO THURSDAY NIGHT. SNOW AMOUNTS ARE EXPECTED TO BE LIGHT...BELOW ADVISORY AMOUNTS IN THE NORTHERN MTNS. && .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 329 AM MST WED DEC 18 2013 HIGH LEVEL CLOUDS HAVE SPREAD ACROSS THE FORECAST AREA AHEAD OF A PACIFIC UPPER LOW APPROACHING THE CA COAST EARLY THIS MORNING. THIS LOW IS GETTING ENTRAINED IN THE NORTHERN STREAM AND WILL BE EJECTED INLAND AS AN OPEN WAVE TODAY AND TRACK ACROSS ERN UT/WRN CO LATE TONIGHT AS A COLDER SHORTWAVE TROUGH DROPS DOWN THE BRITISH COLUMBIA AND THEN PACIFIC NW COAST. PARTLY SUNNY SKIES ARE EXPECTED TODAY WITH TEMPS SIMILAR OR A FEW DEGREES WARMER THAN YESTERDAY IN SW FLOW ALOFT. CLOUDS THICKEN AND LOWER TONIGHT WITH SOME SNOW DEVELOPING ACROSS MAINLY THE CENTRAL AND NORTHERN MTNS AS MODELS SHOW A DECENT AMOUNT OF MOISTURE CONTENT FOR THIS TIME OF YEAR. THE SAN JUANS SHOULD SEE SOME LIGHT ACCUMULATIONS TOWARD THU MORNING AS THE EJECTING CA LOW/TROUGH PASSES. THE POTENTIAL FOR SOME FREEZING RAIN PERSISTS FROM ROUGHLY MIDNIGHT TONIGHT TO SUNRISE THURSDAY...WHEN THAT CA LOW/TROUGH IS EXPECTED TO MOVE PAST. NOT SURE THE MODEL FORECAST SOUNDINGS ARE HANDLING THE VERY SHALLOW COLD AIR TRAPPED IN MANY VALLEYS. MAIN AREA OF CONCERN IS THE WEST-CENTRAL VALLEYS OF WRN CO AND THE EAST-CENTRAL VALLEYS OF ERN UTAH AND POSSIBLY AS FAR SOUTH AS BLANDING AND CORTEZ. WITH LITTLE MIXING EXPECTED TODAY...THE STAGNANT COLD AIR WILL REMAIN OVER THESE SNOW COVERED AREAS. WITH THE WARMER AND MOIST AIR ASSOCIATED WITH THE PACIFIC DISTURBANCE MOVING OVERHEAD...THIS COMBINATION COULD LEAD TO SOME LIGHT FREEZING RAIN IN PLACES. THE TUESDAY FORECAST TEAM ISSUED A SPECIAL WEATHER STATEMENT FOR THIS POSSIBILITY...AND THAT STATEMENT WILL BE CONTINUED. THE COLDER TROUGH DROPPING DOWN THE WEST COAST OF NORTH AMERICA TODAY IS EXPECTED TO SPLIT WITH THE SOUTHERN SECTION FORMING A CLOSED LOW IN THE VICINITY OF LOS ANGELES BY LATE THU AFTERNOON. THIS WILL KEEP SW FLOW ACROSS OUR AREA THU WHILE THE NRN SECTION MOVES ACROSS THE NRN ROCKIES. 700 MB FRONT AND LOW LEVEL CONVERGENCE SET UP NEAR THE CO-WY BORDER AND SHOULD BE THE MAIN FOCUS FOR PRECIPITATION. WILL KEEP HIGHEST POPS ACROSS THE NORTH ON THU. DESPITE SW FLOW ALOFT...THU TEMPS WILL BE COOLER IN MOST PLACES AS COLDER AIR OOZES IN BEHIND THE WED NIGHT DISTURBANCE. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 329 AM MST WED DEC 18 2013 THURSDAY NIGHT AND FRIDAY...THE WARM FRONT WHICH BROUGHT THE MIXED PRECIPITATION TO THE AREA WILL WAVE NORTH THU EVENING WITH MOST PCPN ENDING ACROSS CENTRAL AND SOUTHERN AREAS. THE DEFORMATION ZONE WILL REMAIN STATIONARY OVER THE NORTHERN HALF OF THE AREA...AND PRODUCE ISOLD TO SCATTERED SNOWFALL OVERNIGHT...MAINLY IN THE NORTHERN AND CENTRAL MOUNTAINS. ALL MODELS AGREE ON THIS SCENARIO...BUT THE NAM IS BY FAR THE DRIEST. HAVE STAYED CLOSER TO THE WETTER SOLUTIONS. FOR MOST OF FRIDAY THE DEFORMATION ZONE WILL REMAIN ALONG THE CO/WY BORDER...THEN BEGIN MOVING EAST AND SOUTH AS THE SPLIT TROUGH MOVES EAST AND SOUTH AS WELL. FRIDAY NIGHT THE FLOW ALOFT TURNS NORTHWESTERLY IN THE GFS AND ECMWF AND A SERIES OF VORT MAXES EMBEDDED IN THE NW FLOW WILL MOVE OVER THE AREA... CAUSING CLOUDS AND PCPN TO INCREASE FROM NW TO SE. SATURDAY AND SUNDAY...AS THE EMBEDDED TROUGHS MOVE OVERHEAD... MOISTURE AND PRECIPITATION INCREASE ACROSS THE AREA. THE PERIOD OF HEAVIEST AND MOST WIDESPREAD PCPN APPEARS TO BE SATURDAY THRU SATURDAY EVENING. LATE SAT NIGHT THROUGH SUN SHOULD SEE A RIDGE BUILDING OVER THE WESTERN U.S. WHICH PUSHED THE PCPN BAND EAST. THE FLOW ALOFT SHOULD REMAIN NORTHWESTERLY WITH ENOUGH MOISTURE FOR OROGRAPHIC SNOW SHOWERS TO CONTINUE OVER THE NORTHERN AND CENTRAL CO MOUNTAINS. MONDAY AND TUESDAY SHOULD SEE A CONTINUE DRYING TREND UNDER NORTHWEST FLOW ALOFT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY MORNING) ISSUED AT 1210 PM MST WED DEC 18 2013 VFR CONDITIONS WILL DOMINATE THROUGH THE AFTERNOON AND EARLY EVENING. CLOUDS AND PRECIPITATION WILL INCREASE OVER EASTERN UT THIS EVENING AND SPREAD EAST ACROSS WESTERN CO OVERNIGHT. MVFR CIGS AND VSBYS AREA POSSIBLE ACROSS THE AREA BY ABOUT 07Z WITH SNOW IN THE MOUNTAINS...MIXED RAIN AND SNOW AND EVEN SOME FREEZING RAIN POSSIBLE...IN MOST VALLEYS. MOUNTAIN TOPS WILL BECOME OBSCURED 07Z-15Z...THEN LIMITED TO THE MTNS EAST OF A LINE FROM KCAG TO KGUC AFT 15Z. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ UPDATE...JOE SHORT TERM...JAD LONG TERM...CC AVIATION...JOE/CC
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1007 AM MST WED DEC 18 2013 .UPDATE... && .SHORT TERM...OVERALL...CURRENT FORECASTS LOOK REASONABLE...SOME MINOR ADJUSTMENTS FOR CLOUD COVER AND WIND. FAIRLY EXTENSIVE CLOUD COVER ACROSS MUCH OF THE AREA...LESS OVER THE HIGHER TERRAIN. MOUNTAIN WAVE CLOUDS SITUATED EAST OF THE FOOTHILLS AND URBAN CORRIDOR. MODELS DO INDICATE SOME BREAKUP OF THE WAVE CLOUD DURING THE AFTERNOON...WITH SOME VARIATION. APPEARS THERE WILL BE ENOUGH CLOUD TO SLOW THE EXPECTED WARMUP...EVEN WITH THE WARM BEGINNING. ENOUGH MIXING WILL SHOULD BRING TEMPERATURES INTO THE MIDDLE 60S ACROSS MUCH OF THE PLAINS. IT IS VERY POSSIBLE THE RECORD OF 66 FOR DENVER WILL BE SURPASSED GIVEN THE WARMER AIRMASS AND EXPECTED MIXING. WINDS HAVE BEEN A BIT GUSTY IN AND NEAR FOOTHILLS...SHOULD CONTINUE FOR MUCH OF THE DAY BEFORE DECREASING AS SURFACE GRADIENT WEAKENS. APPEARS TEMPERATURES WILL GO BELOW THE MORNING LOW OF 43 DEGREES AT DENVER DUE TO WEAK EASTERLY WINDS BRINGING COOLER AIR INTO THE AREA...NOT EXPECTING A RECORD LOW MIN FOR THE DAY. FLOW ALOFT GOES FROM WESTERLY TO SOUTHWEST THIS EVENING WITH MORE MID LEVEL MOISTURE STREAMING TOWARD THE AREA. SHOULD SEE SOME OROGRAPHIC SNOW DEVELOPING IN THE PARK AND GORE RANGES SOMETIME AFTER MIDNIGHT. THERE MAY ALSO BE SOME LIGHT SNOW OVER THE FRONT RANGE MOUNTAINS LATE...WITH THE POTENTIAL FOR SOME BANDED PRECIPITATION. .AVIATION...SOUTHWEST WINDS SPREADING ACROSS THE AREA AIRPORTS WITH HELP OF MIXING. SOME GUSTS TO 30 KTS AT KBJC. SHOULD SEE A CONTINUATION OF THE SOUTHWESTERLY WINDS THROUGH THE AFTERNOON... MAY BE MORE WESTERLY AT KDEN BY 20Z. LATEST RAP AND HRRR SUGGESTING WINDS SHIFTING TO THE NORTHWEST BETWEEN 22Z AND 23Z AS GRADIENT BEGINS TO WEAKEN AND WINDS TRY TO GO CLOCKWISE. FOR NOW WILL CONTINUE WITH THE CURRENT TAF TRENDS...WITH THE IDEA OF ENOUGH MIXING WILL KEEP THE WINDS FROM SHIFTING TO THE NORTHWEST. VFR WILL CONTINUE THROUGH THURSDAY AFTERNOON...WITH MID LEVEL MOISTURE INCREASING AFTER MIDNIGHT. COLD FRONT EXPECTED TO MOVE ACROSS THE AREA AIRPORTS AROUND 19 OR 20Z WITH A NORTHERLY WIND SHIFT. SOME LOWERING OF THE CEILING DURING THE AFTERNOON. THERE MAY BE A CEILING OF AROUND 6000 FEET AT KDEN BY 00Z FRIDAY... CHANCES ARE LOW AT THIS TIME. && .PREV DISCUSSION... /ISSUED 449 AM MST WED DEC 18 2013/ SHORT TERM...MAIN QUESTION TODAY IS THE AMOUNT OF CLOUD COVER AND ITS EFFECT ON TEMPERATURES. PLENTY OF MOISTURE UPSTREAM THOUGH THERE IS SOME VARIABILITY. WITH NOT MUCH CHANGE IN THE WIND PATTERN...EXPECT THE WAVE CLOUD COVERING THE PLAINS TO CHANGE LITTLE TODAY WHILE THERE MAY BE SOME DECREASE IN THE HIGH CLOUDS OVER THE MOUNTAINS. CIRA SIMULATED SATELLITE IMAGERY SHOWS A PRETTY SOLID WAVE CLOUD PERSISTING DOWNSTREAM OF THE FRONT RANGE THROUGH TONIGHT WITH POOR AGREEMENT ON THE TIMING OF ANY CLEARING ELSEWHERE. SHOULD BE ENOUGH CLOUDS TO LIMIT TEMPERATURES...BUT THE AIRMASS HAS ALSO WARMED A LITTLE SINCE YESTERDAY. WE WILL BE OFF TO A WARM START...ALREADY IN THE 50S IN THE LOWER FOOTHILLS. UNDER CLEAR SKIES IT WOULD PROBABLY BE 70 IN DENVER TODAY...SO THE CURRENT MID 60S FORECAST IS PROBABLY STILL ALRIGHT. I DID LOWER THE HIGHS A LITTLE IN THE MOUNTAIN VALLEYS ESPECIALLY GRAND COUNTY. THESE AREAS DID NOT WARM AS MUCH YESTERDAY AND COOLED FURTHER OVERNIGHT. CLOUDS THICKEN UP TONIGHT WITH MID LEVEL MOISTURE MOVING INTO THE MOUNTAINS. EXPECT LIGHT OROGRAPHIC SNOW IN THE PARK RANGE...AND POSSIBLY STARTING IN THE FRONT RANGE MOUNTAINS LATE TONIGHT. PREFRONTAL WIND SHIFT TO SOME KIND OF EASTERLY SHOULD BRING COLDER LOWS ON THE PLAINS...THOUGH THIS MAY NOT GET INTO PLACES LIKE BOULDER. LOW SINCE MIDNIGHT OF 43 WOULD BREAK THE RECORD HIGH MIN...WE COULD GET BELOW THAT IF THE WESTERLIES STOP AT DIA BEFORE MIDNIGHT. ALSO FORECASTING A HIGH THERE OF 66 WHICH WOULD TIE THE RECORD FOR THE DATE. LONG TERM...ON THURSDAY...A STRONG SOUTHWESTERLY FLOW ALOFT WILL BE OVER COLORADO AHEAD OF AN UPPER TROUGH THAT WILL STRETCH FM WRN MONTANA INTO NRN CA. THE TROUGH WILL REMAIN TO THE WEST OF COLORADO WITH THE NRN BRANCH MOVING EASTWARD WHILE THE SRN BRANCH SLIDES INTO SRN CALIFORNIA. IN THE MOUNTAINS...SPATIAL CROSS-SECTIONS INDICATE A WSWLY RIDGETOP WINDS AROUND 30 KTS ON THURSDAY. MOISTURE DEEP ENOUGH TO PRODUCE SOME OROGRAPHIC SNOWFALL WHICH WOULD MOST FAVOR ZONES 31 AND 33. WEAK COLD AIR ADVECTION PRESENT SO SUSPECT GENERALLY LIGHT SNOW ALONG AND NORTH OF THE INTERSTATE 70 CORRIDOR. ANY ACCUMULATIONS WILL OCCUR ALONG WEST FACING ASPECTS (2-4 INCHES). FROM THE FRONT RANGE FOOTHILLS EASTWARD...A COLD FRONT WILL MAKE ITS WAY SOUTHWARD BY THE AFTERNOON...WITH NELY UPSLOPE WINDS INCREASING TO AROUND 700 MB BY THURSDAY EVENING. THE CHANCE OF SNOW WILL DECREASE IN THE MOUNTAINS WEST OF THE DIVIDE BUT INCREASE FM NORTH TO SOUTH IN AND NEAR THE FRONT RANGE THURSDAY EVENING. THE BEST CHC OF SNOW WILL BE IN ZONES 35 AND 38...WHERE ACCUMULATIONS OF AN INCH OR TWO MAY BE POSSIBLE...WITH LESSER AMOUNTS IN ZONE 36. THE UPSLOPE WILL BE FAIRLY SHALLOW AND BRIEF WITH CONDITIONS IMPROVING AFTER 09Z THURSDAY NIGHT AS THE LOW LEVEL WINDS BECOME NWLY. AFTER 12Z FRIDAY...THE AIRMASS WILL BE COOLER WITH SHALLOW LOW LEVEL MOISTURE LINGERING UNTIL 15Z...THEN THE AIRMASS WILL BE DRY FROM THE FRONT RANGE FOOTHILLS EASTWARD. THE CHANCE OF SNOW WILL CONTINUE IN THE MOUNTAINS WEST OF THE CONTINENTAL DIVIDE FOR FRIDAY THROUGH SUNDAY. OVERALL THE SNOW AMOUNTS WILL BE LIGHT (UP TO 3 INCHES IN EA 12 HR PERIOD). IT WILL REMAIN COOL IN DENVER ON SATURDAY WITH ANOTHER WEAK BOUT OF UPSLOPE EXPECTED SATURDAY EVENING. NOT MUCH IN THE WAY OF UPPER LEVEL SUPPORT AS A VERY ELONGATED UPPER TROUGH AXIS EVENTUALLY SLIDES ACROSS EASTERN COLORADO LATE SATURDAY. OVERALL QG ASCENT WILL BE NEARLY NEUTRAL SATURDAY NIGHT. THE FLOW ALOFT WILL BE NORTHWESTERLY ON SUNDAY WITH INCREASING SUBSIDENCE EXPECTED. WILL KEEP A CHANCE OF SNOW GOING IN THE MOUNTAINS BUT DRY ELSEWHERE. A GENERALLY DRY NORTHWESTERLY FLOW WILL CONTINUE INTO EARLY NEXT WEEK. THE NEXT STORM SYSTEM IS PROGGED TO DROP OUT OF THE NORTHWEST AND POSSIBLY IMPACT NORTHEAST COLORADO ON CHRISTMAS EVE...WITH A CHANCE OF SNOW FOR THE CWFA ON CHRISTMAS...AT LEAST FOR NOW. AVIATION...VFR THROUGH TONIGHT. WIND WILL BECOME WESTERLY AT KDEN/KAPA WITH GUSTS TO AROUND 20 KNOTS BY MIDDAY...WHILE WEST WINDS GUSTING IN THE 20 TO 30 KNOT RANGE WILL BE COMMON AT KBJC TODAY. WINDS WILL DIMINISH IN THE LATE AFTERNOON OR EARLY EVENING. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....COOPER AVIATION...D-L
AREA FORECAST DISCUSSION
NWS ALBANY NY
100 PM EST WED DEC 18 2013 .SYNOPSIS... AN UPPER LEVEL DISTURBANCE CROSSING THE REGION WILL BRING SCATTERED SNOW SHOWERS AND FLURRIES INTO THE EARLY AFTERNOON. LAKE EFFECT SNOW SHOWERS OR SNOW SQUALLS WILL IMPACT PORTIONS OF THE WESTERN ADIRONDACKS THIS AFTERNOON AND TONIGHT. HIGH PRESSURE WILL BUILD IN FROM THE SOUTHWEST FOR THURSDAY...BRINGING MILDER TEMPERATURES...AND DRY CONDITIONS. A FRONTAL SYSTEM APPROACHING FROM THE WEST AND NORTH WILL BRING CLOUDS...ALONG WITH SOME SNOW AND RAIN SHOWERS FOR THURSDAY NIGHT INTO FRIDAY. A MORE SIGNIFICANT STORM SYSTEM MAY BRING WIDESPREAD PRECIPITATION FOR A PORTION OF THE UPCOMING WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1230 PM EST...DECIDED TO BEGIN THE LAKE EFFECT ADVISORY EARLY AS THE LAKE BAND OFF ONTARIO HAS RAMPED IN THE PAST HOUR. OTHERWISE NO REAL OTHER CHANGES. TEMPERATURES STILL QUITE COLD IN VALLEY AREAS AS MIXING HAS NOT BEEN REALIZED. FEEL PRUDENT TO LOWER MANY VALLEY LOCATIONS ABOUT A CATEGORY BUT KEPT HIGHER ELEVATIONS ABOUT THE SAME. CLOUDS WILL MIX WITH SUNSHINE...MORE SUNSHINE TO THE SOUTH OF THE CAPITAL DISTRICT. LOOK FOR HIGHS GENERALLY 25 TO 30 TO ALBANY SOUTHWARD...20 TO 25 NORTHWARD. LOOK FOR WIDELY SCATTERED SNOW SHOWERS ACROSS MUCH OF THE REGION...WITH LITTLE OR NO ACCUMULATIONS...OUTSIDE OF THE ADIRONDACK PARK WHERE SOME IS LIKELY LATER THIS AFTERNOON AS THE LAKE MACHINE RAMPS UP. THE WIND WILL BECOME WESTERLY 5 TO 15 MPH ACROSS THE REGION. THE LATEST RUC CONTINUED TO SHOW THE H500 TROUGH AXIS...AND ITS ASSOCIATED MID LEVEL SHORT-WAVE MOVING ACROSS WRN NEW ENGLAND. SOME SCT SNOW SHOWER AND FLURRIES HAVE OCCURRED FROM THE CAPITAL REGION NORTH AND WEST...AND ESPECIALLY ALONG THE SPINE OF THE SRN GREENS...N-CNTRL TACONICS...AND BERKSHIRES. SOME SLIGHT AND LOW CHC POPS HAVE BEEN KEPT IN THE FORECAST INTO THE EARLY PM. MOSTLY CLOUDY CONDITIONS PERSIST NORTH OF THE MID HUDSON VALLEY AND NW CT. FURTHER UPSTREAM...DIFFUSE LAKE EFFECT ACTIVITY IS SETTING UP JUST DOWN STREAM OF LAKE ONTARIO. THIS ACTIVITY SHOULD ORGANIZE BETTER IN THE EARLY PM...AND THE LAKE EFFECT SNOW ADVISORY BEGINS FOR NRN HERKIMER AND HAMILTON COUNTIES AT 3 PM. CURRENT FORECAST TRENDS LOOK SIMILAR FOR 3 TO 6 INCHES OF HIGH RATIO SNOWFALL. THE FORECAST TREND LOOKS SIMILAR FOR THE LAKE POTENTIAL BELOW. THE LAKE RESPONSE WILL DEVELOP IN THE PM...AS COOLING WITHIN THE 850-700 MB LAYER COMBINES WITH AN INCREASING LOW LEVEL FLOW OVER WATER TRAJECTORY ACROSS LAKE ONTARIO...WITH SOME ADDITIONAL MOISTENING FROM LAKE HURON. IT APPEARS THAT THE LAKE EFFECT POTENTIAL FOR SINGLE SNOWBANDS WILL BE FOR A SOMEWHAT SHORT DURATION...MAINLY AFTER NOON TODAY...THROUGH AT LEAST 6 PM EST. EXPECT SEVERAL INCHES OF SNOW ACROSS PORTIONS OF NORTHERN HERKIMER CO...AND POSSIBLY EXTENDING INTO PORTIONS OF WEST CENTRAL AND NORTHWEST HAMILTON CO...MAINLY THIS AFTERNOON. SOME EXTENSION OF A SNOWBAND MAY ALSO IMPACT PORTIONS OF THE MOHAWK VALLEY/WRN CAPITAL REGION EARLY THIS THIS AFTERNOON...WITH MINOR ACCUMS POSSIBLE. ENHANCED UPSLOPE ACROSS PORTIONS OF SOUTHERN VT COULD ALSO LEAD TO A COUPLE INCHES OF SNOWFALL ACROSS EASTERN PORTIONS OF BENNINGTON CO AND WEST CENTRAL WINDHAM CO THIS AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... TONIGHT...THE AFOREMENTIONED SNOWBAND WILL LIKELY BE ONGOING THIS EVENING ACROSS THE ADVISORY AREA...AND LIFTING NORTHWARD...IMPACTING AREAS NEAR AND NORTH OF ROUTE 28. LATER TONIGHT...IT APPEARS THAT THE BAND SHOULD WEAKEN AS THE INVERSION LEVEL DROPS RAPIDLY...AND LOW LEVEL DIRECTIONAL SHEAR INCREASES AND DISRUPTS SINGLE BAND POTENTIAL. ELSEWHERE...EXPECT PARTLY CLOUDY SKIES...ALTHOUGH SOME PERIODS OF MOSTLY CLEAR SKIES WILL BE POSSIBLE. GIVEN OUR DEEP...FRESH SNOWPACK...ANY BREAKS IN THE CLOUDS WILL ALLOW TEMPS TO QUICKLY DROP. HAVE THEREFORE WENT BELOW THE COLDEST GUIDANCE...WITH MAINLY SINGLE DIGITS AND TEENS EXPECTED. SHOULD BREAKS IN THE CLOUDS BE MORE WIDESPREAD AND/OR LONGER IN DURATION...EVEN COLDER MIN TEMPS WOULD BE POSSIBLE. THU...LOW AND MID LEVEL WARM ADVECTION DEVELOPS AND STRENGTHENS. AS MILDER AND INCREASINGLY MOIST AIR MOVES OVER THE VERY COLD GROUND AND DEEP SNOW COVER...IT APPEARS THAT A LOW LEVEL INVERSION WILL DEVELOP...LEADING TO MOSTLY CLOUDY SKIES FOR AT LEAST THE NORTHERN THIRD OF THE REGION...WITH OCCASIONAL CLOUDS TO THE SOUTH. FOR MAX TEMPS...HAVE SIDED WITH THE COOLER OF THE MAV/MET MOS...WITH GENERALLY 30S EXPECTED FOR VALLEY AREAS...AND 20S TO AROUND 30 FOR HIGHER ELEVATIONS. THU NT-FRI NT...A FRONTAL BOUNDARY WILL GRADUALLY APPROACH FROM THE N AND W...AS WAVES OF LOW PRESSURE TRAVEL ALONG IT. SEVERAL SURGES OF ISENTROPIC LIFT WILL IMPACT THE REGION...ESP NORTHERN AND CENTRAL AREAS. IT APPEARS THAT THE BEST CHC FOR PRECIP WILL BE LATE THU NT INTO FRI EVENING. WARMING ALOFT COULD ALLOW FOR SOME MIXED PRECIP TO OCCUR ACROSS NORTHERN AREAS THU NT...AND AGAIN FRI NT...AND WILL HAVE TO WATCH MODEL TRENDS AND LOW LEVEL THERMAL PROFILES. QPF LOOKS LIGHT AT THIS TIME...BUT CAN NOT RULE OUT SOME AREAS OF LIGHT ICING...ESP FRI NT ACROSS PORTIONS OF THE SOUTHERN ADIRONDACKS AND WESTERN MOHAWK VALLEY. HAVE SIDED WITH...OR WENT BELOW THE COOLER MAV/MET...WITH NIGHTTIME MINS FALLING INTO THE 20S IN MOST AREAS...AND MAX TEMPS RANGING FROM THE UPPER 20S TO MID 30S ACROSS NORTHERN AREAS...AND MID 30S TO MID 40S ACROSS SOUTHERN AREAS. && .LONG TERM /SATURDAY THROUGH TUESDAY/... STILL DECENT AGREEMENT IN GUIDANCE AND ENSEMBLES FOR A STRONG WARM ADVECTION EVENT THAT SHOULD RESULT IN MORE RAIN THAN WINTRY PRECIPITATION. ONE SYSTEM WILL BE EXITING THROUGH SATURDAY MORNING WITH JUST SCATTERED RAIN AND SNOW SHOWERS ENDING. THE NEXT SYSTEM...WITH SOUTHERN STREAM ORIGINS...SPREADS MOSTLY RAIN OVER MUCH OF THE REGION SATURDAY AFTERNOON...STARTING AS A MIX IN THE SOUTHERN ADIRONDACKS. THERE COULD BE MINOR TO MODERATE ACCUMULATIONS OF MIXED PRECIPITATION...INCLUDING POSSIBLY FREEZING RAIN...IN THE SOUTHERN ADIRONDACKS THROUGH SATURDAY NIGHT BEFORE PRECIPITATION TURNS TO RAIN SUNDAY MORNING. THIS COULD BE A PROLONGED EVENT...WITH A VERY STRONG WEST SOUTHWESTERLY BOUNDARY LAYER JET AND DEEP MOISTURE...ALONG WITH STRONG ISENTROPIC LIFT WITHIN THE WARM ADVECTION...AND STRONG FRONTOGENESIS ALONG THE COLD FRONT. THERE COULD BE ENOUGH RAIN FOR SOME POTENTIAL RUN OFF PROBLEMS WHEN COMBINED WITH SNOW MELT. THE AXIS OF HEAVIEST RAIN LOOKS TO BE ALONG AND NORTH OF THE SCHOHARIE VALLEY...SOUTHERN ADIRONDACKS...HELDERBERGS TO THE LAKE GEORGE SARATOGA REGION...SOUTHERN GREEN MOUNTAINS AND BERKSHIRES. SOME INDICATIONS ARE THAT THE HEAVIEST RAIN COULD BE MOSTLY THE EXTREME NORTHERN SECTIONS OF THE FORECAST AREA...SO THERE IS CONSIDERABLE UNCERTAINTY ON WHERE THE HEAVIEST RAIN COULD FALL. THE POTENTIAL FOR HEAVY RAIN...SNOW MELT AND RUN OFF WILL BE ADDRESSED IN THE HWO. HIGHS SATURDAY IN THE 40S...MID TO UPPER 30S SOUTHERN ADIRONDACKS AND SOUTHERN GREEN MOUNTAINS. HIGHS SUNDAY IN THE LOWER TO MID 50S...WITH 40S IN HIGHER ELEVATIONS...AROUND 40 SOUTHERN ADIRONDACKS. THE FRONT TRACKS THROUGH SUNDAY NIGHT AND EARLY MONDAY WITH DEEP COLD ADVECTION SPREADING ACROSS OUR REGION. HIGHS MONDAY IN THE LOWER TO MID 30S...WITH UPPER 20S IN THE SOUTHERN ADIRONDACKS AND SOUTHERN GREEN MOUNTAINS. COLD ADVECTION CONTINUES TUESDAY WITH HIGHS IN THE 20S...UPPER TEENS IN THE SOUTHERN ADIRONDACKS. THERE COULD BE LAKE EFFECT SNOW BANDS MONDAY INTO TUESDAY BUT THE INLAND EXTENT IS IN QUESTION. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... A WEAK WARM FRONT WILL MOVE NORTH OF THE REGION THIS AFTERNOON. HIGH PRESSURE WILL RIDGE IN FROM THE MID ATLANTIC REGION TONIGHT INTO EARLY TOMORROW AFTERNOON. IN THE MOIST CYCLONIC FLOW ALOFT OCCASIONAL CLOUDS CONTINUE TO IMPACT THE TERMINALS FROM KALB AND KPSF NORTHWARD TO KGFL. ALSO A WEAK WARM FRONT IS LIFTING THROUGH THESE AREAS. SOME OF THE CLOUDS HAVE BEEN IN THE HIGH MVFR RANGE AT THESE SITES. THESE MVFR CLOUDS WILL BE POSSIBLE UNTIL THE LATE AFTERNOON/EARLY EVENING ESPECIALLY AT KGFL. FURTHER SOUTH...ONLY HIGH CLOUDS HAVE BEEN PERSISTING NEAR KPOU. VFR CONDITIONS ARE EXPECTED TO RETURN TO ALL THE TAF SITES THIS EVENING WITH LINGERING STRATOCUMULUS...TRANSITIONING TO MID AND HIGH CLOUDS WITH THE WARM ADVECTION OCCURRING ALOFT...AS THE SFC RIDGE ATTEMPTS TO BUILD IN. EXPECT WIDESPREAD MID LEVEL AND HIGH CLOUDS IN THE LATE MORNING FOR KGFL/KALB/KPOU/KPSF. THE WINDS WILL BE LIGHT FROM THE SOUTH TO SOUTHWEST AT LESS THAN 7 KTS INITIALLY...AND THEN WILL VEER TO THE WEST AT AROUND 10 KTS WITH SOME GUSTS CLOSER 20 KTS AT KALB IN THE LATE PM. THE WINDS WILL THEN BACK TO THE SOUTH TO SOUTHWEST EARLY THIS EVENING AT 5 TO 10 KTS. EXPECT THE SOUTH TO SOUTHWEST WINDS TO CONTINUE AT AROUND 10 KTS WITH GUSTS CLOSER TO 20 KTS AT KALB. OUTLOOK... THURSDAY PM...NO OPERATIONAL IMPACT. NO SIG WX. THURSDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. FRIDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN. FRIDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN. SATURDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...RA. SATURDAY NIGHT: HIGH OPERATIONAL IMPACT. LIKELY RA. SUNDAY: HIGH OPERATIONAL IMPACT. LIKELY RA. SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF RA. MONDAY: MODERATE OPERATIONAL IMPACT. SCATTERED SHRA...SHSN. && .HYDROLOGY... LAKE EFFECT SNOWBANDS...AND SCATTERED SNOW SHOWERS WILL BE POSSIBLE TODAY AND TONIGHT...WITH MAXIMUM TOTAL LIQUID EQUIVALENT GENERALLY REMAINING UNDER ONE QUARTER OF AN INCH...WHICH WOULD BE ACROSS THE WESTERN ADIRONDACKS. OTHERWISE...THROUGH TONIGHT...TEMPS WILL CONTINUE TO BE BELOW NORMAL AND ICE WILL CONTINUE TO FORM AND THICKEN ON AREA RIVERS...STREAMS AND PARTICULARLY LAKES. A MODERATING TREND IN TEMPS IS LIKELY THU INTO FRI...WITH A FRONTAL BOUNDARY BRINGING SOME SHOWERS TO CLOSE THE WORK WEEK. SOME SNOW MELT IS LIKELY THIS WEEKEND. ALSO...A STORM SYSTEM MOVING ALONG A FRONTAL BOUNDARY MAY BRING SIGNIFICANT PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY WITH EVEN MILDER TEMPS. THIS WILL CONTINUE TO BE MONITORED FOR THE UPCOMING WEEKEND FOR THE POSSIBILITY OF SOME HYDRO ISSUES. 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...LAKE EFFECT SNOW ADVISORY UNTIL 6 AM EST THURSDAY FOR NYZ032- 033. MA...NONE. VT...NONE. && $$ SYNOPSIS...KL/WASULA NEAR TERM...HWJIV/KL/WASULA SHORT TERM...KL LONG TERM...NAS AVIATION...WASULA HYDROLOGY...KL/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
1230 PM EST WED DEC 18 2013 .SYNOPSIS... AN UPPER LEVEL DISTURBANCE CROSSING THE REGION WILL BRING SCATTERED SNOW SHOWERS AND FLURRIES INTO THE EARLY AFTERNOON. LAKE EFFECT SNOW SHOWERS OR SNOW SQUALLS WILL IMPACT PORTIONS OF THE WESTERN ADIRONDACKS THIS AFTERNOON AND TONIGHT. HIGH PRESSURE WILL BUILD IN FROM THE SOUTHWEST FOR THURSDAY...BRINGING MILDER TEMPERATURES...AND DRY CONDITIONS. A FRONTAL SYSTEM APPROACHING FROM THE WEST AND NORTH WILL BRING CLOUDS...ALONG WITH SOME SNOW AND RAIN SHOWERS FOR THURSDAY NIGHT INTO FRIDAY. A MORE SIGNIFICANT STORM SYSTEM MAY BRING WIDESPREAD PRECIPITATION FOR A PORTION OF THE UPCOMING WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1230 PM EST...DECIDED TO BEGIN THE LAKE EFFECT ADVISORY EARLY AS THE LAKE BAND OFF ONTARIO HAS RAMPED IN THE PAST HOUR. OTHERWISE NO REAL OTHER CHANGES. TEMPERATURES STILL QUITE COLD IN VALLEY AREAS AS MIXING HAS NOT BEEN REALIZED. FEEL PRUDENT TO LOWER MANY VALLEY LOCATIONS ABOUT A CATEGORY BUT KEPT HIGHER ELEVATIONS ABOUT THE SAME. CLOUDS WILL MIX WITH SUNSHINE...MORE SUNSHINE TO THE SOUTH OF THE CAPITAL DISTRICT. LOOK FOR HIGHS GENERALLY 25 TO 30 TO ALBANY SOUTHWARD...20 TO 25 NORTHWARD. LOOK FOR WIDELY SCATTERED SNOW SHOWERS ACROSS MUCH OF THE REGION...WITH LITTLE OR NO ACCUMULATIONS...OUTSIDE OF THE ADIRONDACK PARK WHERE SOME IS LIKELY LATER THIS AFTERNOON AS THE LAKE MACHINE RAMPS UP. THE WIND WILL BECOME WESTERLY 5 TO 15 MPH ACROSS THE REGION. THE LATEST RUC CONTINUED TO SHOW THE H500 TROUGH AXIS...AND ITS ASSOCIATED MID LEVEL SHORT-WAVE MOVING ACROSS WRN NEW ENGLAND. SOME SCT SNOW SHOWER AND FLURRIES HAVE OCCURRED FROM THE CAPITAL REGION NORTH AND WEST...AND ESPECIALLY ALONG THE SPINE OF THE SRN GREENS...N-CNTRL TACONICS...AND BERKSHIRES. SOME SLIGHT AND LOW CHC POPS HAVE BEEN KEPT IN THE FORECAST INTO THE EARLY PM. MOSTLY CLOUDY CONDITIONS PERSIST NORTH OF THE MID HUDSON VALLEY AND NW CT. FURTHER UPSTREAM...DIFFUSE LAKE EFFECT ACTIVITY IS SETTING UP JUST DOWN STREAM OF LAKE ONTARIO. THIS ACTIVITY SHOULD ORGANIZE BETTER IN THE EARLY PM...AND THE LAKE EFFECT SNOW ADVISORY BEGINS FOR NRN HERKIMER AND HAMILTON COUNTIES AT 3 PM. CURRENT FORECAST TRENDS LOOK SIMILAR FOR 3 TO 6 INCHES OF HIGH RATIO SNOWFALL. THE FORECAST TREND LOOKS SIMILAR FOR THE LAKE POTENTIAL BELOW. THE LAKE RESPONSE WILL DEVELOP IN THE PM...AS COOLING WITHIN THE 850-700 MB LAYER COMBINES WITH AN INCREASING LOW LEVEL FLOW OVER WATER TRAJECTORY ACROSS LAKE ONTARIO...WITH SOME ADDITIONAL MOISTENING FROM LAKE HURON. IT APPEARS THAT THE LAKE EFFECT POTENTIAL FOR SINGLE SNOWBANDS WILL BE FOR A SOMEWHAT SHORT DURATION...MAINLY AFTER NOON TODAY...THROUGH AT LEAST 6 PM EST. EXPECT SEVERAL INCHES OF SNOW ACROSS PORTIONS OF NORTHERN HERKIMER CO...AND POSSIBLY EXTENDING INTO PORTIONS OF WEST CENTRAL AND NORTHWEST HAMILTON CO...MAINLY THIS AFTERNOON. SOME EXTENSION OF A SNOWBAND MAY ALSO IMPACT PORTIONS OF THE MOHAWK VALLEY/WRN CAPITAL REGION EARLY THIS THIS AFTERNOON...WITH MINOR ACCUMS POSSIBLE. ENHANCED UPSLOPE ACROSS PORTIONS OF SOUTHERN VT COULD ALSO LEAD TO A COUPLE INCHES OF SNOWFALL ACROSS EASTERN PORTIONS OF BENNINGTON CO AND WEST CENTRAL WINDHAM CO THIS AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... TONIGHT...THE AFOREMENTIONED SNOWBAND WILL LIKELY BE ONGOING THIS EVENING ACROSS THE ADVISORY AREA...AND LIFTING NORTHWARD...IMPACTING AREAS NEAR AND NORTH OF ROUTE 28. LATER TONIGHT...IT APPEARS THAT THE BAND SHOULD WEAKEN AS THE INVERSION LEVEL DROPS RAPIDLY...AND LOW LEVEL DIRECTIONAL SHEAR INCREASES AND DISRUPTS SINGLE BAND POTENTIAL. ELSEWHERE...EXPECT PARTLY CLOUDY SKIES...ALTHOUGH SOME PERIODS OF MOSTLY CLEAR SKIES WILL BE POSSIBLE. GIVEN OUR DEEP...FRESH SNOWPACK...ANY BREAKS IN THE CLOUDS WILL ALLOW TEMPS TO QUICKLY DROP. HAVE THEREFORE WENT BELOW THE COLDEST GUIDANCE...WITH MAINLY SINGLE DIGITS AND TEENS EXPECTED. SHOULD BREAKS IN THE CLOUDS BE MORE WIDESPREAD AND/OR LONGER IN DURATION...EVEN COLDER MIN TEMPS WOULD BE POSSIBLE. THU...LOW AND MID LEVEL WARM ADVECTION DEVELOPS AND STRENGTHENS. AS MILDER AND INCREASINGLY MOIST AIR MOVES OVER THE VERY COLD GROUND AND DEEP SNOW COVER...IT APPEARS THAT A LOW LEVEL INVERSION WILL DEVELOP...LEADING TO MOSTLY CLOUDY SKIES FOR AT LEAST THE NORTHERN THIRD OF THE REGION...WITH OCCASIONAL CLOUDS TO THE SOUTH. FOR MAX TEMPS...HAVE SIDED WITH THE COOLER OF THE MAV/MET MOS...WITH GENERALLY 30S EXPECTED FOR VALLEY AREAS...AND 20S TO AROUND 30 FOR HIGHER ELEVATIONS. THU NT-FRI NT...A FRONTAL BOUNDARY WILL GRADUALLY APPROACH FROM THE N AND W...AS WAVES OF LOW PRESSURE TRAVEL ALONG IT. SEVERAL SURGES OF ISENTROPIC LIFT WILL IMPACT THE REGION...ESP NORTHERN AND CENTRAL AREAS. IT APPEARS THAT THE BEST CHC FOR PRECIP WILL BE LATE THU NT INTO FRI EVENING. WARMING ALOFT COULD ALLOW FOR SOME MIXED PRECIP TO OCCUR ACROSS NORTHERN AREAS THU NT...AND AGAIN FRI NT...AND WILL HAVE TO WATCH MODEL TRENDS AND LOW LEVEL THERMAL PROFILES. QPF LOOKS LIGHT AT THIS TIME...BUT CAN NOT RULE OUT SOME AREAS OF LIGHT ICING...ESP FRI NT ACROSS PORTIONS OF THE SOUTHERN ADIRONDACKS AND WESTERN MOHAWK VALLEY. HAVE SIDED WITH...OR WENT BELOW THE COOLER MAV/MET...WITH NIGHTTIME MINS FALLING INTO THE 20S IN MOST AREAS...AND MAX TEMPS RANGING FROM THE UPPER 20S TO MID 30S ACROSS NORTHERN AREAS...AND MID 30S TO MID 40S ACROSS SOUTHERN AREAS. && .LONG TERM /SATURDAY THROUGH TUESDAY/... STILL DECENT AGREEMENT IN GUIDANCE AND ENSEMBLES FOR A STRONG WARM ADVECTION EVENT THAT SHOULD RESULT IN MORE RAIN THAN WINTRY PRECIPITATION. ONE SYSTEM WILL BE EXITING THROUGH SATURDAY MORNING WITH JUST SCATTERED RAIN AND SNOW SHOWERS ENDING. THE NEXT SYSTEM...WITH SOUTHERN STREAM ORIGINS...SPREADS MOSTLY RAIN OVER MUCH OF THE REGION SATURDAY AFTERNOON...STARTING AS A MIX IN THE SOUTHERN ADIRONDACKS. THERE COULD BE MINOR TO MODERATE ACCUMULATIONS OF MIXED PRECIPITATION...INCLUDING POSSIBLY FREEZING RAIN...IN THE SOUTHERN ADIRONDACKS THROUGH SATURDAY NIGHT BEFORE PRECIPITATION TURNS TO RAIN SUNDAY MORNING. THIS COULD BE A PROLONGED EVENT...WITH A VERY STRONG WEST SOUTHWESTERLY BOUNDARY LAYER JET AND DEEP MOISTURE...ALONG WITH STRONG ISENTROPIC LIFT WITHIN THE WARM ADVECTION...AND STRONG FRONTOGENESIS ALONG THE COLD FRONT. THERE COULD BE ENOUGH RAIN FOR SOME POTENTIAL RUN OFF PROBLEMS WHEN COMBINED WITH SNOW MELT. THE AXIS OF HEAVIEST RAIN LOOKS TO BE ALONG AND NORTH OF THE SCHOHARIE VALLEY...SOUTHERN ADIRONDACKS...HELDERBERGS TO THE LAKE GEORGE SARATOGA REGION...SOUTHERN GREEN MOUNTAINS AND BERKSHIRES. SOME INDICATIONS ARE THAT THE HEAVIEST RAIN COULD BE MOSTLY THE EXTREME NORTHERN SECTIONS OF THE FORECAST AREA...SO THERE IS CONSIDERABLE UNCERTAINTY ON WHERE THE HEAVIEST RAIN COULD FALL. THE POTENTIAL FOR HEAVY RAIN...SNOW MELT AND RUN OFF WILL BE ADDRESSED IN THE HWO. HIGHS SATURDAY IN THE 40S...MID TO UPPER 30S SOUTHERN ADIRONDACKS AND SOUTHERN GREEN MOUNTAINS. HIGHS SUNDAY IN THE LOWER TO MID 50S...WITH 40S IN HIGHER ELEVATIONS...AROUND 40 SOUTHERN ADIRONDACKS. THE FRONT TRACKS THROUGH SUNDAY NIGHT AND EARLY MONDAY WITH DEEP COLD ADVECTION SPREADING ACROSS OUR REGION. HIGHS MONDAY IN THE LOWER TO MID 30S...WITH UPPER 20S IN THE SOUTHERN ADIRONDACKS AND SOUTHERN GREEN MOUNTAINS. COLD ADVECTION CONTINUES TUESDAY WITH HIGHS IN THE 20S...UPPER TEENS IN THE SOUTHERN ADIRONDACKS. THERE COULD BE LAKE EFFECT SNOW BANDS MONDAY INTO TUESDAY BUT THE INLAND EXTENT IS IN QUESTION. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... MAINLY VFR CONDITIONS THIS AFTERNOON AT THE TAF SITES...BUT OCCASIONAL MVFR THIS AFTERNOON AT KPSF. AN UPPER LEVEL DISTURBANCE TRACKING THROUGH THE REGION WILL BRING PERIODS OF BROKEN CEILINGS ABOVE 3000 FEET THROUGH THE DAY. THERE COULD BE SOME FLURRIES THIS MORNING SO WILL PUT VCSH FOR A FEW HOURS AT KALB...KPSF...AND KGFL. AT THE SURFACE...HIGH PRESSURE WILL BUILD IN. SCATTERED VARIABLE BROKEN CEILINGS ABOVE 3000 FEET SHOULD CONTINUE THROUGH TONIGHT MAINLY AT KALB...KPSF AND KGFL BUT JUST SCATTERED AT KPOU. WINDS WILL BE LIGHT TO CALM THROUGH THE EARLY MORNING HOURS BECOMING WESTERLY DURING THE LATE MORNING AND INCREASING TO 6 TO 10 KNOTS. SOME GUSTS INTO THE TEENS ARE EXPECTED AT KALB AND KPSF FROM LATE MORNING THROUGH THE MID AFTERNOON...AND SHOULD CONTINUE INTO THE EVENING. WINDS SHOULD DECREASE TO 5 KT OR LESS LATER THIS EVENING AND CONTINUE THROUGH THE NIGHT. OUTLOOK... THURSDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. FRIDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN. FRIDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN. SATURDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...RA. SATURDAY NIGHT: HIGH OPERATIONAL IMPACT. LIKELY RA. SUNDAY: HIGH OPERATIONAL IMPACT. LIKELY RA. && .HYDROLOGY... LAKE EFFECT SNOWBANDS...AND SCATTERED SNOW SHOWERS WILL BE POSSIBLE TODAY AND TONIGHT...WITH MAXIMUM TOTAL LIQUID EQUIVALENT GENERALLY REMAINING UNDER ONE QUARTER OF AN INCH...WHICH WOULD BE ACROSS THE WESTERN ADIRONDACKS. OTHERWISE...THROUGH TONIGHT...TEMPS WILL CONTINUE TO BE BELOW NORMAL AND ICE WILL CONTINUE TO FORM AND THICKEN ON AREA RIVERS...STREAMS AND PARTICULARLY LAKES. A MODERATING TREND IN TEMPS IS LIKELY THU INTO FRI...WITH A FRONTAL BOUNDARY BRINGING SOME SHOWERS TO CLOSE THE WORK WEEK. SOME SNOW MELT IS LIKELY THIS WEEKEND. ALSO...A STORM SYSTEM MOVING ALONG A FRONTAL BOUNDARY MAY BRING SIGNIFICANT PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY WITH EVEN MILDER TEMPS. THIS WILL CONTINUE TO BE MONITORED FOR THE UPCOMING WEEKEND FOR THE POSSIBILITY OF SOME HYDRO ISSUES. 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...LAKE EFFECT SNOW ADVISORY UNTIL 6 AM EST THURSDAY FOR NYZ032- 033. MA...NONE. VT...NONE. && $$ SYNOPSIS...KL/WASULA NEAR TERM...HWJIV/KL/WASULA SHORT TERM...KL LONG TERM...NAS AVIATION...HWJIV/NAS HYDROLOGY...KL/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
1145 AM EST WED DEC 18 2013 .SYNOPSIS... AN UPPER LEVEL DISTURBANCE CROSSING THE REGION WILL BRING SCATTERED SNOW SHOWERS AND FLURRIES INTO THE EARLY AFTERNOON. LAKE EFFECT SNOW SHOWERS OR SNOW SQUALLS WILL IMPACT PORTIONS OF THE WESTERN ADIRONDACKS THIS AFTERNOON AND TONIGHT. HIGH PRESSURE WILL BUILD IN FROM THE SOUTHWEST FOR THURSDAY...BRINGING MILDER TEMPERATURES...AND DRY CONDITIONS. A FRONTAL SYSTEM APPROACHING FROM THE WEST AND NORTH WILL BRING CLOUDS...ALONG WITH SOME SNOW AND RAIN SHOWERS FOR THURSDAY NIGHT INTO FRIDAY. A MORE SIGNIFICANT STORM SYSTEM MAY BRING WIDESPREAD PRECIPITATION FOR A PORTION OF THE UPCOMING WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1145 AM EST...NO REAL CHANGES TO THE ONGOING FORECAST. HOWEVER...TEMPERATURES STILL QUITE COLD IN VALLEY AREAS AS MIXING HAS NOT BEEN REALIZED. FEEL PRUDENT TO LOWER MANY VALLEY LOCATIONS ABOUT A CATEGORY BUT KEPT HIGHER ELEVATIONS ABOUT THE SAME. CLOUDS WILL MIX WITH SUNSHINE...MORE SUNSHINE TO THE SOUTH OF THE CAPITAL DISTRICT. LOOK FOR HIGHS GENERALLY 25 TO 30 TO ALBANY SOUTHWARD...20 TO 25 NORTHWARD. LOOK FOR WIDELY SCATTERED SNOW SHOWERS ACROSS MUCH OF THE REGION...WITH LITTLE OR NO ACCUMULATIONS...OUTSIDE OF THE ADIRONDACK PARK WHERE SOME IS LIKELY LATER THIS AFTERNOON AS THE LAKE MACHINE RAMPS UP. THE WIND WILL BECOME WESTERLY 5 TO 15 MPH ACROSS THE REGION. THE LATEST RUC CONTINUED TO SHOW THE H500 TROUGH AXIS...AND ITS ASSOCIATED MID LEVEL SHORT-WAVE MOVING ACROSS WRN NEW ENGLAND. SOME SCT SNOW SHOWER AND FLURRIES HAVE OCCURRED FROM THE CAPITAL REGION NORTH AND WEST...AND ESPECIALLY ALONG THE SPINE OF THE SRN GREENS...N-CNTRL TACONICS...AND BERKSHIRES. SOME SLIGHT AND LOW CHC POPS HAVE BEEN KEPT IN THE FORECAST INTO THE EARLY PM. MOSTLY CLOUDY CONDITIONS PERSIST NORTH OF THE MID HUDSON VALLEY AND NW CT. FURTHER UPSTREAM...DIFFUSE LAKE EFFECT ACTIVITY IS SETTING UP JUST DOWN STREAM OF LAKE ONTARIO. THIS ACTIVITY SHOULD ORGANIZE BETTER IN THE EARLY PM...AND THE LAKE EFFECT SNOW ADVISORY BEGINS FOR NRN HERKIMER AND HAMILTON COUNTIES AT 3 PM. CURRENT FORECAST TRENDS LOOK SIMILAR FOR 3 TO 6 INCHES OF HIGH RATIO SNOWFALL. THE FORECAST TREND LOOKS SIMILAR FOR THE LAKE POTENTIAL BELOW. THE LAKE RESPONSE WILL DEVELOP IN THE PM...AS COOLING WITHIN THE 850-700 MB LAYER COMBINES WITH AN INCREASING LOW LEVEL FLOW OVER WATER TRAJECTORY ACROSS LAKE ONTARIO...WITH SOME ADDITIONAL MOISTENING FROM LAKE HURON. IT APPEARS THAT THE LAKE EFFECT POTENTIAL FOR SINGLE SNOWBANDS WILL BE FOR A SOMEWHAT SHORT DURATION...MAINLY AFTER NOON TODAY...THROUGH AT LEAST 6 PM EST. EXPECT SEVERAL INCHES OF SNOW ACROSS PORTIONS OF NORTHERN HERKIMER CO...AND POSSIBLY EXTENDING INTO PORTIONS OF WEST CENTRAL AND NORTHWEST HAMILTON CO...MAINLY THIS AFTERNOON. SOME EXTENSION OF A SNOWBAND MAY ALSO IMPACT PORTIONS OF THE MOHAWK VALLEY/WRN CAPITAL REGION EARLY THIS THIS AFTERNOON...WITH MINOR ACCUMS POSSIBLE. ENHANCED UPSLOPE ACROSS PORTIONS OF SOUTHERN VT COULD ALSO LEAD TO A COUPLE INCHES OF SNOWFALL ACROSS EASTERN PORTIONS OF BENNINGTON CO AND WEST CENTRAL WINDHAM CO THIS AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... TONIGHT...THE AFOREMENTIONED SNOWBAND WILL LIKELY BE ONGOING THIS EVENING ACROSS THE ADVISORY AREA...AND LIFTING NORTHWARD...IMPACTING AREAS NEAR AND NORTH OF ROUTE 28. LATER TONIGHT...IT APPEARS THAT THE BAND SHOULD WEAKEN AS THE INVERSION LEVEL DROPS RAPIDLY...AND LOW LEVEL DIRECTIONAL SHEAR INCREASES AND DISRUPTS SINGLE BAND POTENTIAL. ELSEWHERE...EXPECT PARTLY CLOUDY SKIES...ALTHOUGH SOME PERIODS OF MOSTLY CLEAR SKIES WILL BE POSSIBLE. GIVEN OUR DEEP...FRESH SNOWPACK...ANY BREAKS IN THE CLOUDS WILL ALLOW TEMPS TO QUICKLY DROP. HAVE THEREFORE WENT BELOW THE COLDEST GUIDANCE...WITH MAINLY SINGLE DIGITS AND TEENS EXPECTED. SHOULD BREAKS IN THE CLOUDS BE MORE WIDESPREAD AND/OR LONGER IN DURATION...EVEN COLDER MIN TEMPS WOULD BE POSSIBLE. THU...LOW AND MID LEVEL WARM ADVECTION DEVELOPS AND STRENGTHENS. AS MILDER AND INCREASINGLY MOIST AIR MOVES OVER THE VERY COLD GROUND AND DEEP SNOW COVER...IT APPEARS THAT A LOW LEVEL INVERSION WILL DEVELOP...LEADING TO MOSTLY CLOUDY SKIES FOR AT LEAST THE NORTHERN THIRD OF THE REGION...WITH OCCASIONAL CLOUDS TO THE SOUTH. FOR MAX TEMPS...HAVE SIDED WITH THE COOLER OF THE MAV/MET MOS...WITH GENERALLY 30S EXPECTED FOR VALLEY AREAS...AND 20S TO AROUND 30 FOR HIGHER ELEVATIONS. THU NT-FRI NT...A FRONTAL BOUNDARY WILL GRADUALLY APPROACH FROM THE N AND W...AS WAVES OF LOW PRESSURE TRAVEL ALONG IT. SEVERAL SURGES OF ISENTROPIC LIFT WILL IMPACT THE REGION...ESP NORTHERN AND CENTRAL AREAS. IT APPEARS THAT THE BEST CHC FOR PRECIP WILL BE LATE THU NT INTO FRI EVENING. WARMING ALOFT COULD ALLOW FOR SOME MIXED PRECIP TO OCCUR ACROSS NORTHERN AREAS THU NT...AND AGAIN FRI NT...AND WILL HAVE TO WATCH MODEL TRENDS AND LOW LEVEL THERMAL PROFILES. QPF LOOKS LIGHT AT THIS TIME...BUT CAN NOT RULE OUT SOME AREAS OF LIGHT ICING...ESP FRI NT ACROSS PORTIONS OF THE SOUTHERN ADIRONDACKS AND WESTERN MOHAWK VALLEY. HAVE SIDED WITH...OR WENT BELOW THE COOLER MAV/MET...WITH NIGHTTIME MINS FALLING INTO THE 20S IN MOST AREAS...AND MAX TEMPS RANGING FROM THE UPPER 20S TO MID 30S ACROSS NORTHERN AREAS...AND MID 30S TO MID 40S ACROSS SOUTHERN AREAS. && .LONG TERM /SATURDAY THROUGH TUESDAY/... STILL DECENT AGREEMENT IN GUIDANCE AND ENSEMBLES FOR A STRONG WARM ADVECTION EVENT THAT SHOULD RESULT IN MORE RAIN THAN WINTRY PRECIPITATION. ONE SYSTEM WILL BE EXITING THROUGH SATURDAY MORNING WITH JUST SCATTERED RAIN AND SNOW SHOWERS ENDING. THE NEXT SYSTEM...WITH SOUTHERN STREAM ORIGINS...SPREADS MOSTLY RAIN OVER MUCH OF THE REGION SATURDAY AFTERNOON...STARTING AS A MIX IN THE SOUTHERN ADIRONDACKS. THERE COULD BE MINOR TO MODERATE ACCUMULATIONS OF MIXED PRECIPITATION...INCLUDING POSSIBLY FREEZING RAIN...IN THE SOUTHERN ADIRONDACKS THROUGH SATURDAY NIGHT BEFORE PRECIPITATION TURNS TO RAIN SUNDAY MORNING. THIS COULD BE A PROLONGED EVENT...WITH A VERY STRONG WEST SOUTHWESTERLY BOUNDARY LAYER JET AND DEEP MOISTURE...ALONG WITH STRONG ISENTROPIC LIFT WITHIN THE WARM ADVECTION...AND STRONG FRONTOGENESIS ALONG THE COLD FRONT. THERE COULD BE ENOUGH RAIN FOR SOME POTENTIAL RUN OFF PROBLEMS WHEN COMBINED WITH SNOW MELT. THE AXIS OF HEAVIEST RAIN LOOKS TO BE ALONG AND NORTH OF THE SCHOHARIE VALLEY...SOUTHERN ADIRONDACKS...HELDERBERGS TO THE LAKE GEORGE SARATOGA REGION...SOUTHERN GREEN MOUNTAINS AND BERKSHIRES. SOME INDICATIONS ARE THAT THE HEAVIEST RAIN COULD BE MOSTLY THE EXTREME NORTHERN SECTIONS OF THE FORECAST AREA...SO THERE IS CONSIDERABLE UNCERTAINTY ON WHERE THE HEAVIEST RAIN COULD FALL. THE POTENTIAL FOR HEAVY RAIN...SNOW MELT AND RUN OFF WILL BE ADDRESSED IN THE HWO. HIGHS SATURDAY IN THE 40S...MID TO UPPER 30S SOUTHERN ADIRONDACKS AND SOUTHERN GREEN MOUNTAINS. HIGHS SUNDAY IN THE LOWER TO MID 50S...WITH 40S IN HIGHER ELEVATIONS...AROUND 40 SOUTHERN ADIRONDACKS. THE FRONT TRACKS THROUGH SUNDAY NIGHT AND EARLY MONDAY WITH DEEP COLD ADVECTION SPREADING ACROSS OUR REGION. HIGHS MONDAY IN THE LOWER TO MID 30S...WITH UPPER 20S IN THE SOUTHERN ADIRONDACKS AND SOUTHERN GREEN MOUNTAINS. COLD ADVECTION CONTINUES TUESDAY WITH HIGHS IN THE 20S...UPPER TEENS IN THE SOUTHERN ADIRONDACKS. THERE COULD BE LAKE EFFECT SNOW BANDS MONDAY INTO TUESDAY BUT THE INLAND EXTENT IS IN QUESTION. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... MAINLY VFR CONDITIONS THIS AFTERNOON AT THE TAF SITES...BUT OCCASIONAL MVFR THIS AFTERNOON AT KPSF. AN UPPER LEVEL DISTURBANCE TRACKING THROUGH THE REGION WILL BRING PERIODS OF BROKEN CEILINGS ABOVE 3000 FEET THROUGH THE DAY. THERE COULD BE SOME FLURRIES THIS MORNING SO WILL PUT VCSH FOR A FEW HOURS AT KALB...KPSF...AND KGFL. AT THE SURFACE...HIGH PRESSURE WILL BUILD IN. SCATTERED VARIABLE BROKEN CEILINGS ABOVE 3000 FEET SHOULD CONTINUE THROUGH TONIGHT MAINLY AT KALB...KPSF AND KGFL BUT JUST SCATTERED AT KPOU. WINDS WILL BE LIGHT TO CALM THROUGH THE EARLY MORNING HOURS BECOMING WESTERLY DURING THE LATE MORNING AND INCREASING TO 6 TO 10 KNOTS. SOME GUSTS INTO THE TEENS ARE EXPECTED AT KALB AND KPSF FROM LATE MORNING THROUGH THE MID AFTERNOON...AND SHOULD CONTINUE INTO THE EVENING. WINDS SHOULD DECREASE TO 5 KT OR LESS LATER THIS EVENING AND CONTINUE THROUGH THE NIGHT. OUTLOOK... THURSDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN. FRIDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN. FRIDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN. SATURDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...RA. SATURDAY NIGHT: HIGH OPERATIONAL IMPACT. LIKELY RA. SUNDAY: HIGH OPERATIONAL IMPACT. LIKELY RA. && .HYDROLOGY... LAKE EFFECT SNOWBANDS...AND SCATTERED SNOW SHOWERS WILL BE POSSIBLE TODAY AND TONIGHT...WITH MAXIMUM TOTAL LIQUID EQUIVALENT GENERALLY REMAINING UNDER ONE QUARTER OF AN INCH...WHICH WOULD BE ACROSS THE WESTERN ADIRONDACKS. OTHERWISE...THROUGH TONIGHT...TEMPS WILL CONTINUE TO BE BELOW NORMAL AND ICE WILL CONTINUE TO FORM AND THICKEN ON AREA RIVERS...STREAMS AND PARTICULARLY LAKES. A MODERATING TREND IN TEMPS IS LIKELY THU INTO FRI...WITH A FRONTAL BOUNDARY BRINGING SOME SHOWERS TO CLOSE THE WORK WEEK. SOME SNOW MELT IS LIKELY THIS WEEKEND. ALSO...A STORM SYSTEM MOVING ALONG A FRONTAL BOUNDARY MAY BRING SIGNIFICANT PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY WITH EVEN MILDER TEMPS. THIS WILL CONTINUE TO BE MONITORED FOR THE UPCOMING WEEKEND FOR THE POSSIBILITY OF SOME HYDRO ISSUES. 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...LAKE EFFECT SNOW ADVISORY FROM 3 PM THIS AFTERNOON TO 6 AM EST THURSDAY FOR NYZ032-033. MA...NONE. VT...NONE. && $$ SYNOPSIS...KL/WASULA NEAR TERM...HWJIV/KL/WASULA SHORT TERM...KL LONG TERM...NAS AVIATION...HWJIV/NAS HYDROLOGY...KL/WASULA
AREA FORECAST DISCUSSION
NWS GOODLAND KS
236 PM MST WED DEC 18 2013 .SHORT TERM...(THIS AFTERNOON THROUGH THURSDAY) ISSUED AT 100 PM MST WED DEC 18 2013 LATEST WV IMAGERY AND RAP H5 ANALYSIS INDICATES WESTERLY ZONAL FLOW IN PLACE ACROSS THE UNITED STATES...WITH TWO SHORTWAVE TROUGHS UPSTREAM OFF THE WEST COAST. THE FIRST TROUGH IS CENTERED OVER BRITISH COLUMBIA...WITH THE SECOND JUST WEST OF THE BAJA PENINSULA. AT THE SURFACE A TROUGH OF LOW PRESSURE EXTENDS FROM EASTERN COLORADO AND ACROSS SOUTH WEST NEBRASKA. A COLD FRONT IS IN PLACE ACROSS CENTRAL MONTANA AND NORTH DAKOTA WITH AN ARCTIC HIGH PRESSURE SYSTEM LURKING TO THE NORTH OF THE FEATURE READY TO MAKE A TREK SOUTH INTO THE PLAINS. WITH WESTERLY CROSS MOUNTAIN FLOW AND EMBEDDED UPPER LEVEL ENERGY CONTINUE TO MOVE EAST I WOULD EXPECT CLOUD COVER TO BEGIN TO INCREASE ONCE AGAIN TONIGHT...ESPECIALLY AFTER MIDNIGHT AS A TROUGH BEGINS TO MOVE FROM THE PAC NW AND DEEPEN ACROSS THE GREAT BASIN. CLOUD COVER COULD HAVE A NEGATIVE IMPACT ON RADIATIONAL COOLING...AND I WAS NOT CONFIDENT IN HOW LOW WE WILL ACTUALLY DROP BEFORE WINDS POSSIBLY INCREASE TOWARDS DAYBREAK THURSDAY. I HAVE TRENDED TEMPS UP A LITTLE. TEMPERATURE FORECAST THURSDAY IS COMPLICATED BY TIMING OF ARCTIC FRONT ARRIVAL. NAM/GFS CONTINUE TO SHOW FROPA IN THE 12-18Z TIME PERIOD...WITH THE LATEST RUNS OF THE ECMWF/GEM SEEM TO FAVOR AN AFTERNOON FRONTAL PASSAGE. CONTINUITY AND PERSONAL EXPERIENCE WOULD FAVOR THE QUICKER PASSAGE...HOWEVER WITH ABOUT 6HR OF SPREAD IN SOLUTIONS THIS COULD HAVE A LARGE IMPACT ON HIGH TEMPS. GOING BY THE COLDER END OF GUIDANCE NORTHERN HALF OF THE CWA LIKELY WOULDNT MAKE IT ABOVE FREEZING AND TEMPS WOULD BE FALLING TO THE 20S BY MID AFTERNOON. WARMER END OF GUIDANCE ALLOWS ENOUGH OF A WINDOW FOR TEMPS TO RISE TO AT LEAST THE UPPER 40S IF NOT THE LOW 50S ACROSS THE SOUTH. I NUDGED THE FORECAST TOWARDS THE FASTER GUIDANCE...HOWEVER CONFIDENCE IS NOT PARTICULARLY HIGH ON HOW THIS WILL TIME OUT. WE COULD END UP SEEING HIGHS IN THE NORTH OCCURRING IN THE EARLY MORNING NEAR SUNRISE. GUIDANCE CONTINUES TO SHOW INCREASING MID LEVEL MOISTURE AND WEAK FORCING FROM THE NORTHWEST...SO I COULDNT RULE OUT A FEW FLURRIES BY LATE THURSDAY AFTERNOON. I LEFT MENTION IN PLACE OVER YUMA COUNTY IN LINE WITH PREVIOUS FORECAST. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 234 PM MST WED DEC 18 2013 WESTERLY FLOW WILL CONTINUE THROUGH FRIDAY AHEAD OF A TROUGH MOVING SOUTHEAST FROM SOUTHERN CALIFORNIA. THE TROUGH WILL MOVE EAST INTO EASTERN NEW MEXICO SATURDAY. SURFACE HIGH PRESSURE WILL MOVE INTO THE CENTRAL PLAINS THURSDAY NIGHT AND FRIDAY. A SURFACE TROUGH WILL MOVE INTO EASTERN COLORADO FRIDAY NIGHT. THIS TROUGH WILL MOVE SOUTH INTO TEXAS SATURDAY WITH A COLD FRONT FOLLOWING. THERE WILL BE SOME FLURRIES POSSIBLE THURSDAY NIGHT AS COLDER AIR FILTERS INTO THE REGION BEHIND THE COLD FRONT. PLAN TO CONTINUE THIS AREA OF FLURRIES OVER THE NORTHWEST FA WHERE H8-7 LAYER MEAN MOISTURE IS BEST. OTHERWISE POPS WILL BE NIL THROUGH FRIDAY NIGHT DUE TO SUBSIDENCE. THE UPPER TROUGH OVER EASTERN NEW MEXICO WILL BRING A SLIGHT CHANCE OF LIGHT SNOW TO THE FAR SOUTHEAST ZONES SATURDAY AS DYNAMICS MOVE ACROSS SOUTHWEST AND SOUTHCENTRAL KANSAS. MIN TEMPERATURES THURSDAY NIGHT WILL FALL INTO THE LOWER TEENS AND COULD BE COLDER IF SKIES CLEAR. THE COLDEST AIR MOVES AWAY SO THAT LOW TEMPERATURES FRIDAY NIGHT WILL BE IN THE UPPER TEENS. MAX TEMPERATURES WILL RANGE FROM 30 TO AROUND 35 FRIDAY AND 35 TO AROUND 40 SATURDAY. IN THE EXTENDED...(SATURDAY NIGHT THROUGH WEDNESDAY)... SOME LIGHT SNOW WILL BE POSSIBLE SATURDAY NIGHT AS THE ABOVE MENTIONED TROUGH MOVES EAST ACROSS THE CENTRAL/SOUTHERN PLAINS. SLIGHT CHANCE POPS WILL BE OVER THE EXTREME SOUTHEAST FA WHERE MOISTURE IS BEST. UPPER FLOW WILL BECOME NORTHWEST SUNDAY AND CONTINUE THROUGH WEDNESDAY. SUBSIDENCE DURING THIS TIME WILL BRING DRY CONDITIONS. MIN TEMPERATURES WILL RANGE FROM THE TEENS SATURDAY THROUGH SUNDAY NIGHTS WARMING TO THE LOWER 20S MONDAY THROUGH WEDNESDAY NIGHTS. MAX TEMPERATURES SUNDAY WILL BE IN THE LOWER 30S. SOME WARMING INTO THE 40S WILL OCCUR MONDAY THROUGH WEDNESDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1022 AM MST WED DEC 18 2013 VFR CONDITIONS WILL PREVAIL AT BOTH KGLD AND KMCK TERMINALS. WEST WINDS GENERALLY BELOW 12KTS WILL BECOME LIGHT AND VARIABLE AROUND 00Z AS DAYTIME HEATING ENDS AND A SURFACE TROUGH SHIFTS EAST. WINDS WILL THEN SHIFT TO THE NORTH AND INCREASE TO 10-12KT RANGE LATE TONIGHT AS A FRONT APPROACHES THE REGION. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...FS AVIATION...DR
AREA FORECAST DISCUSSION
NWS GOODLAND KS
102 PM MST WED DEC 18 2013 .SHORT TERM...(THIS AFTERNOON THROUGH THURSDAY) ISSUED AT 100 PM MST WED DEC 18 2013 LATEST WV IMAGERY AND RAP H5 ANALYSIS INDICATES WESTERLY ZONAL FLOW IN PLACE ACROSS THE UNITED STATES...WITH TWO SHORTWAVE TROUGHS UPSTREAM OFF THE WEST COAST. THE FIRST TROUGH IS CENTERED OVER BRITISH COLUMBIA...WITH THE SECOND JUST WEST OF THE BAJA PENINSULA. AT THE SURFACE A TROUGH OF LOW PRESSURE EXTENDS FROM EASTERN COLORADO AND ACROSS SOUTH WEST NEBRASKA. A COLD FRONT IS IN PLACE ACROSS CENTRAL MONTANA AND NORTH DAKOTA WITH AN ARCTIC HIGH PRESSURE SYSTEM LURKING TO THE NORTH OF THE FEATURE READY TO MAKE A TREK SOUTH INTO THE PLAINS. WITH WESTERLY CROSS MOUNTAIN FLOW AND EMBEDDED UPPER LEVEL ENERGY CONTINUE TO MOVE EAST I WOULD EXPECT CLOUD COVER TO BEGIN TO INCREASE ONCE AGAIN TONIGHT...ESPECIALLY AFTER MIDNIGHT AS A TROUGH BEGINS TO MOVE FROM THE PAC NW AND DEEPEN ACROSS THE GREAT BASIN. CLOUD COVER COULD HAVE A NEGATIVE IMPACT ON RADIATIONAL COOLING...AND I WAS NOT CONFIDENT IN HOW LOW WE WILL ACTUALLY DROP BEFORE WINDS POSSIBLY INCREASE TOWARDS DAYBREAK THURSDAY. I HAVE TRENDED TEMPS UP A LITTLE. TEMPERATURE FORECAST THURSDAY IS COMPLICATED BY TIMING OF ARCTIC FRONT ARRIVAL. NAM/GFS CONTINUE TO SHOW FROPA IN THE 12-18Z TIME PERIOD...WITH THE LATEST RUNS OF THE ECMWF/GEM SEEM TO FAVOR AN AFTERNOON FRONTAL PASSAGE. CONTINUITY AND PERSONAL EXPERIENCE WOULD FAVOR THE QUICKER PASSAGE...HOWEVER WITH ABOUT 6HR OF SPREAD IN SOLUTIONS THIS COULD HAVE A LARGE IMPACT ON HIGH TEMPS. GOING BY THE COLDER END OF GUIDANCE NORTHERN HALF OF THE CWA LIKELY WOULDNT MAKE IT ABOVE FREEZING AND TEMPS WOULD BE FALLING TO THE 20S BY MID AFTERNOON. WARMER END OF GUIDANCE ALLOWS ENOUGH OF A WINDOW FOR TEMPS TO RISE TO AT LEAST THE UPPER 40S IF NOT THE LOW 50S ACROSS THE SOUTH. I NUDGED THE FORECAST TOWARDS THE FASTER GUIDANCE...HOWEVER CONFIDENCE IS NOT PARTICULARLY HIGH ON HOW THIS WILL TIME OUT. WE COULD END UP SEEING HIGHS IN THE NORTH OCCURRING IN THE EARLY MORNING NEAR SUNRISE. GUIDANCE CONTINUES TO SHOW INCREASING MID LEVEL MOISTURE AND WEAK FORCING FROM THE NORTHWEST...SO I COULDNT RULE OUT A FEW FLURRIES BY LATE THURSDAY AFTERNOON. I LEFT MENTION IN PLACE OVER YUMA COUNTY IN LINE WITH PREVIOUS FORECAST. .LONG TERM...(SATURDAY THROUGH WEDNESDAY) ISSUED AT 1208 AM MST WED DEC 18 2013 SHORTWAVE TROUGH AXIS WILL BE MOVING THROUGH THE PLAINS ON SATURDAY. BEST DYNAMICS WILL BE IN THE SOUTHERN PLAINS BUT THERE WILL BE LOW CHANCES FOR LIGHT SNOW ACROSS THE SOUTHEASTERN FORECAST AREA. SHORTWAVE RIDGING WILL FOLLOW FOR SUNDAY AND MONDAY WITH DRY CONDITIONS AND BELOW NORMAL TEMPERATURES ON SUNDAY REBOUNDING QUICKLY TO ABOVE NORMAL ON MONDAY. NEXT SYSTEM WILL BE MOVING OUT OF THE NORTHERN ROCKIES MIDWEEK...BRINGING ANOTHER SHOT OF SLIGHTLY COLDER AIR ON WEDNESDAY. ALTHOUGH MODELS ARE IN POOR AGREEMENT ON EVOLUTION OF THIS SYSTEM AS IT DIGS INTO THE PLAINS...PRECIPITATION CHANCES APPEAR SLIM TO NONE. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1022 AM MST WED DEC 18 2013 VFR CONDITIONS WILL PREVAIL AT BOTH KGLD AND KMCK TERMINALS. WEST WINDS GENERALLY BELOW 12KTS WILL BECOME LIGHT AND VARIABLE AROUND 00Z AS DAYTIME HEATING ENDS AND A SURFACE TROUGH SHIFTS EAST. WINDS WILL THEN SHIFT TO THE NORTH AND INCREASE TO 10-12KT RANGE LATE TONIGHT AS A FRONT APPROACHES THE REGION. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...DR LONG TERM...024 AVIATION...DR
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1203 PM CST WED DEC 18 2013 .UPDATED FOR 18Z AVIATION DISCUSSION... ISSUED AT 1131 AM CST WED DEC 18 2013 && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 400 AM CST WED DEC 18 2013 AT THIS TIME YESTERDAY MORNING...THE FORECAST AREA WAS 15-30 DEGREES WARMER THAN WE ARE CURRENTLY. THE THERMOMETER WILL GET A WORKOUT TODAY AND EVEN AFTER A CHILLY START...WE SHOULD REBOUND QUITE WELL BY THE AFTERNOON. THE SURFACE RIDGE WILL BE OUT OVER LAKE MICHIGAN BY 15Z AND THE APPROACHING CLIPPER SHOULD BE NEARING THE WESTERN MN BORDER AROUND THE SAME TIME. THE WARM AIR ADVECTION OUT AHEAD OF THE SURFACE LOW THIS MORNING IS IMPRESSIVE AND IT`S THE REASON WE`RE FORECASTING THE WARMEST TEMPERATURES WE`VE SEEN IN OVER TWO WEEKS. THE 18.07Z RAP HAS NEARLY THE ENTIRE FORECAST AREA ABOVE 0C AT 925MB BY 00Z THIS EVENING /6-10C ACROSS MUCH OF WESTERN MN/ AND YOU`RE NOT SEEING THINGS...THAT IS INDEED THE 0C ISOTHERM NEAR THE MN/IA BORDER AT 700 MB. THIS SAME BUBBLE OF WARM AIR WAS OVER WESTERN NE AND SD YESTERDAY AND BROUGHT HIGHS BETWEEN 40-60. NOW THE WARMEST TEMPS WERE IN SNOW FREE AREAS...BUT LOWER 40S WERE OBSERVED EVEN WHERE THERE WAS SNOW ON THE GROUND. WE WILL CERTAINLY BE COOLER THAN WHAT THE PLAINS OBSERVED YESTERDAY...BUT THE DOWNSLOPE AREAS OF THE BUFFALO RIDGE COULD EASILY SEE SOME LOWER 40S...ESPECIALLY IF WE ESTABLISH A SOUTHWEST COMPONENT TO THE WIND BEFORE THE NOON HOUR. THE MIXING WILL NOT BE GREAT TODAY...ESPECIALLY WITH THE MORNING INVERSION AND SNOW COVER. WE SHOULDN`T MIX AS HIGH AS 925MB AND THIS WILL KEEP HIGHS FROM GETTING TOO WARM. WE HOPE THIS LACK OF MIXING DOESN`T MEAN WE`RE MUCH TOO WARM WITH THE TEMPS TODAY - VERIFICATION HAS SHOWN A WARM BIAS LATELY - THOUGH THAT HAS BEEN WITH 15 TO 30 DEGREE DEPARTURES FROM NORMAL. WE LIKE THE 18.00Z NAM MOS IN THAT IT KEPT THE WESTERN FORECAST AREA WARM AND COOLED THE EAST. THERE SHOULD BE A LARGE WEST-EAST TEMPERATURE GRADIENT TODAY /LOWER 40S FAR WEST - MID TO UPPER 20S FAR EAST/. THE TWIN CITIES METRO IS RIGHT IN THE MIDDLE OF THIS GRADIENT. THERE IS VIRTUALLY NO CHANCE FOR PRECIP IN THE SHORT TERM...BUT PATCHY BLOWING SNOW CAN NOT BE COMPLETELY RULED OUT LATE TONIGHT WHEN A PRONOUNCED AREA OF MSLP PRESSURE RISES SLIDES ACROSS MN BEHIND THE CLIPPER SYSTEM. WE SAW BLOWING SNOW YESTERDAY IN WESTERN MN...BUT THAT WAS WITH BL WINDS THAT WERE 5-7 KTS STRONGER. IN ADDITION...THE WARMER TEMPS TODAY SHOULD PROBABLY ACT TO SETTLE THE CURRENT SNOW PACK A BIT. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 400 AM CST WED DEC 18 2013 ARCTIC AIR WILL OOZE IN ON THURSDAY AS A 1035MB HIGH BUILDS SOUTHWARD INTO THE WESTERN HIGH PLAINS. WHILE THIS IS OCCURRING... A SHORT WAVE WILL MOVE EAST FROM THE NORTHERN ROCKIES DURING THE DAY BRINGING A SURGE OF MID LEVEL MOISTURE TO THE REGION. AMPLE UPGLIDE... SATURATION AND ADIABATIC OMEGA ON THE NAM/GFS 290K THETA SURFACES SPREAD INTO WEST CENTRAL MN BY NOON ON THURSDAY AND ACROSS THE CWA BY EVENING. MIXING RATIOS RISE TO BETWEEN 2 AND 3 G/KG. HOWEVER...THE BEST ADIABATIC OMEGA ONLY LASTS FOR ABOUT 6 HOURS. CONTINUED THE TREND OF RAISING POPS WITH LIKELY FOR THURSDAY AFTERNOON IN WEST CENTRAL MN WITH CATEGORICAL IN PLACE FROM SOUTHWEST MN THROUGH THE TWIN CITIES AND ACROSS MUCH OF WEST CENTRAL WI FOR THURSDAY EVENING. THE SNOW THEN TAPERS OFF GRADUALLY OVERNIGHT FROM WEST TO EAST WITH SOME LINGERING LIGHT SNOW FOR SOUTH CENTRAL MN THROUGH WEST CENTRAL WI ON FRIDAY. SNOW AMOUNTS OF 1.5 TO 2 INCHES ARE LIKELY BY DAYBREAK FRIDAY... ESPECIALLY ON AN EAST-WEST AXIS THAT RUNS THROUGH THE SOUTH METRO...WITH A FEW MORE TENTHS OF AN INCH ON FRIDAY TO THE EAST AND SOUTH OF THE METRO. THE HIGH TO OUR WEST WILL BUILD IN FOR SATURDAY WITH A DRY BUT COLD DAY. DIFFERENCES THEN EVOLVE BETWEEN THE ECMWF...GFS AND GEM ON THE LATTER HALF OF THE WEEKEND AS A STORM SYSTEM EXITS THE SOUTH PLAINS. THE ECMWF REMAINS DRY WITH THE NORTHWEST EDGE OF THE PRECIPITATION FROM THIS SOUTHERN SYSTEM STAYING TO OUR SOUTHEAST. THE GEM GOES HOG WILD DEVELOPING A CLOSED H7 LOW OVER US BY SATURDAY NIGHT WITH 3 TO 5 INCHES OF SNOW FOR SATURDAY NIGHT AND SUNDAY. THE GFS IS IN BETWEEN...HAVING TROUBLE SEPARATING THE NORTHERN AND SOUTHERN STREAM ENERGY. COLLABORATION WAS TO FOLLOW MORE OF THE DRY ECMWF SOLUTION AND REDUCE POPS FROM THE CR EXTEND. A SECOND ARCTIC HIGH WILL BUILD IN FROM SUNDAY INTO MONDAY WITH SOME VERY COLD AIR. DROPPED LOWS TO NEAR 15 BELOW FOR PORTIONS OF CENTRAL MN FOR MONDAY MORNING WITH AROUND 5 BELOW IN THE TWIN CITIES AND ZERO IN EAU CLAIRE. THIS MAY NOT BE COLD ENOUGH IF THE ECMWF IS CORRECT WITH IT/S GUIDANCE SUGGESTING LOWERING LOWS ANOTHER 5 TO 10 DEGREES. SOME MODERATION IS EXPECTED BY CHRISTMAS EVE DAY AS THE FLOW ALOFT BECOMES MORE WESTERLY AND THE HIGH DEPARTS TO OUR SOUTHEAST. HOWEVER...ANOTHER SHORT WAVE AND LOW PRESSURE SYSTEM ARE RIDING THE ARCTIC FRONT WITH SOME MORE SNOW POSSIBLE CHRISTMAS EVE AND CHRISTMAS DAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1131 AM CST WED DEC 18 2013 VFR CONDITIONS SHOULD TODAY AHEAD OF AN APPROACHING COLD FRONT FROM THE NORTH. ONCE THE FRONT PASSES THROUGH WINDS WILL INCREASE OUT OF THE NORTH...WITH GUSTS NEAR 20KTS AT TIMES. THERE IS INDICATION THAT MVFR CLOUDS WILL DEVELOP BEHIND THE FRONT AS WELL FOR WEDNESDAY MORNING. LOOKING AHEAD...SNOW WILL DEVELOP DURING THE AFTERNOON. KMSP... FRONTAL PASSAGE SHOULD BE AROUND 06Z...WITH NORTHERLY WINDS THEREAFTER. MVFR CLOUDS CLOUD DEVELOP POST FRONTAL...SO HAVE BROKEN DECK AFTER MIDNIGHT. /OUTLOOK FOR KMSP/ WED EVENING...MVFR/IFR AND -SN. WINDS N AT 10KTS. THU...LINGERING MVFR/IFR AND -SN. WINDS NW AT 10G20KTS. FRI...VFR. WINDS SW AT 05KTS. SAT...VFR. WINDS NW AT 10KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...CLF LONG TERM...RAH AVIATION...JRB
AREA FORECAST DISCUSSION
NWS ELKO NV
1131 AM PST WED DEC 18 2013 .SYNOPSIS...A LOW PRESSURE SYSTEM WILL BRING SNOW TO THE GREAT BASIN TONIGHT AND THURSDAY. SNOW SHOWERS ARE EXPECTED AGAIN OVER THE WEEKEND. ALTHOUGH THERE MAY BE SOME SNOW SHOWERS AROUND...AT THIS TIME NO TRAVEL CONCERNS ARE ANTICIPATED FOR THE WEEK OF CHRISTMAS. && .UPDATE...IN THE NEXT COUPLE OF HOURS...ISOLATED RAIN SHOWERS ARE EXPECTED TO MOVE INTO PORTIONS OF NORTHER LANDER AND EXTREME SOUTHEAST HUMBOLDT COUNTY. WITH THE STRONG INVERSION IN PLACE...VALLEY TEMPERATURES REMAIN BELOW FREEZING. THIS WILL CREATE ISOLATED AREAS OF LIGHT FREEZING RAIN THROUGH THE AFTERNOON. SOME SLICK SPOTS ARE POSSIBLE ON I80 AND STATE ROUTE 305. ALSO RAISED POPS ACROSS CENTRAL NEVADA AND LOWERED TEMPS ACROSS ENTIRE CWA. && .PREV DISCUSSION... /ISSUED AT 259 AM / SYNOPSIS...A LOW PRESSURE SYSTEM WILL BRING SNOW TO THE GREAT BASIN TONIGHT AND THURSDAY. SNOW SHOWERS ARE EXPECTED AGAIN OVER THE WEEKEND. ALTHOUGH THERE MAY BE SOME SNOW SHOWERS AROUND...AT THIS TIME NO TRAVEL CONCERNS ARE ANTICIPATED FOR THE WEEK OF CHRISTMAS. SHORT TERM...TODAY THROUGH FRIDAY. HIGH PRESSURE TO OUR SOUTH IS BATTLING AN INCOMING SHORTWAVE THIS MORNING. IR IMAGERY SHOWS A LOT OF MID TO HIGH CLOUDINESS SPREADING ACROSS THE SIERRA MOUNTAIN RANGE AND INTO THE GREAT BASIN AS PACIFIC MOISTURE ALOFT ASSOCIATED WITH THE TROUGH TO BE BEGINS STREAMING INTO OREGON AND WASHINGTON STATE. WATER VAPOR IMAGERY REVEALS FEWER CLOUDS ACROSS NORTHWEST NEVADA AT THIS TIME...BETWIXT THE TWO UPPER LEVEL FEATURES. OTHERWISE...PRETTY QUIET THIS MORNING. TEMPERATURES ARE WARMER THAN RECENT NIGHTS AND DEW POINTS ARE 10 DEGREES OR MORE ALL ACROSS THE BOARD. THE MODELS SEEM TO BE IN VERY GOOD AGREEMENT FOR THE SHORT TERM. WEDNESDAY MORNING. THIS WILL BE A DRY PERIOD. THERE MAY STILL BE SOME POCKETS OF FOG AHEAD OF ANTICIPATED TROUGH DEVELOPMENT...MORE LIKELY IN THE AREA OF WINNEMUCCA WHERE CLOUDINESS IS LESS EVIDENT. WEDNESDAY AFTERNOON THROUGH EARLY WEDNESDAY EVENING. A TROUGH WILL BEGIN TO DEVELOP OVER CANADA AND DROP DOWN. THE TROUGH AXIS WILL ALIGN THROUGH OR/WA/CA BY LATE EVENING. THE RR QUAD REGIONS OF A TWIN JET CORE IS SHOWN TO BEGIN INFILTRATING NORTHERN NEVADA BY THIS EVENING. LIGHT SNOW SHOWERS ARE EXPECTED TO BEGIN OVER CENTRAL NEVADA THIS AFTERNOON AND THEN DEVELOP ACROSS MOST AREAS BY THIS EVENING. HIGH TEMPERATURES WILL RANGE FROM THE MID 30S NORTH TO THE MID 50S SOUTH OF HIGHWAY 50. LATE WEDNESDAY EVENING THROUGH THURSDAY NIGHT. A WINTER STORM WATCH IS IN EFFECT FOR NORTHERN NYE AND WHITE PINE COUNTIES. A TROUGH AXIS WILL TRAVERSE THE GREAT BASIN AS CENTRAL LOW PRESSURE DEEPENS WHILE IT RELOCATES TO THE NORTHERN BAJA REGION. A STRONG AREA OF LOW LEVEL CONVERGENCE WILL CENTER OVER WHITE PINE COUNTY AND MODEL QPF IS SIGNIFICANT OVER NYE COUNTY AND WHITE PINE COUNTY. AT THIS TIME APPEARS THIS SYSTEM COULD PRODUCE 3 TO 5 INCHES OF SNOWFALL TO THE VALLEYS OF CENTRAL NEVADA WITH ELEVATIONS ABOVE 6500 FEET RECEIVING A FOOT OF SNOW. VALLEY AMOUNTS MAY CHANGE SO THE WINTER STORM WATCH WAS NOT ISSUED FOR A SPECIFIC ELEVATION. AN INCH OR TWO OF SNOW IS EXPECTED ELSEWHERE INCLUDING THE ELKO AND SPRING CREEK AREAS. WINDS WILL BE BREEZY ACROSS HUMBOLDT COUNTY AS MEAN LOW PRESSURE DROPS BEHIND THE SIERRAS IN THE AFTERNOON. SHOWERS SHOULD RAPIDLY TAPER OFF AROUND MIDNIGHT. LEFT SOME LOW POPS IN FOR WHITE PINE COUNTY AFTER MIDNIGHT THURSDAY. HIGH TEMPERATURES WILL RANGE FROM THE MID 20S NORTH TO AROUND 40 SOUTH OF HIGHWAY 50. LOW TEMPERATURES WILL BE IN THE 20S WEDNESDAY NIGHT AND IN THE SINGLE DIGITS THURSDAY NIGHT. FRIDAY. A SHORT WAVE RIDGE WILL BEGIN TO RAPIDLY PUSH ACROSS THE GREAT BASIN. A NORTHWEST FLOW ALOFT INDICATES THIS SHALLOW RIDGE WILL BE DIRTY. SO INTRODUCED LOW POPS ACROSS NORTHERN NEVADA. HIGH TEMPERATURES WILL BE IN THE 20S TO AROUND 30 DEGREES. LONG TERM...FRIDAY NIGHT THROUGH NEXT TUESDAY. THE PERIOD COMMENCES WITH COASTAL RIDGING FROM BRITISH COLUMBIA TO SOUTHERN CALIFORNIA WITH THE TROF AXIS OVER THE ROCKIES...AND THE JET CORE OVER THE SILVER STATE. THE JET PLACEMENT...ALONG WITH THE SPIKE IN PWS SUGGEST SNOW ACCUMULATIONS IN EASTERN HUMBOLDT COUNTY AND PORTIONS OF ELKO COUNTY...WITH THE BEST ACCUMULATIONS IN OROGRAPHICALLY FAVORED NORTH FACING SLOPES. THE VALLEYS OF ELKO AND EASTERN HUMBOLDT COUNTY WILL LIKELY RECEIVE LESS THAN 2 INCHES OF SNOW FRIDAY NIGHT INTO SATURDAY. AS TIME ELAPSES...SHOWERS TAPER OFF ACROSS NORTHEASTERN NEVADA INTO SUNDAY...WITH SOME LINGERING ISOLATED SHOWERS POSSIBLE ACROSS MOUNTAINS. THE NAEFS AND THE GFS ARE BOTH SHOWING NEAR NORMAL TEMPERATURES TO SLIGHTLY ABOVE NORMAL TEMPERATURES BY DAY 7. THE ONLY CONCERN HERE IS THAT THE MODELS MAY BE WARMING IT UP A SKOSH TOO FAST IN THE GREAT BASIN...AS OFTEN...SNOW EVENTS FOLLOWED BY NORTHERLY FLOW RESULT IN COLD TEMPS. INTERESTINGLY...THE RMOP OF THE ENSEMBLE MEAN FORECAST...SHOWS STRONG/HIGH RMOP OVER THE LKN CWA LATE IN THE PERIOD BUT STRUGGLES EARLIER IN THE PERIOD WITH THE NORTHERLY FLOW. AVIATION...VFR CONDITIONS ARE EXPECTED AT ALL TAF SITES. && .LKN WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM 10 PM PST THIS EVENING THROUGH THURSDAY EVENING FOR NORTHEASTERN NYE COUNTY...NORTHWESTERN NYE COUNTY... WHITE PINE COUNTY. && $$ 94/99
AREA FORECAST DISCUSSION
NWS PORTLAND OR
928 AM PST WED DEC 18 2013 .SYNOPSIS...A COLD UPPER LEVEL TROUGH WILL BRING INCREASING SHOWERS LATER THIS MORNING AND AFTERNOON FOR SW WASHINGTON AND NW OREGON...AND LATE THIS AFTERNOON AND EVENING FOR THE CENTRAL/SOUTH WILLAMETTE VALLEY AND THE CASCADES. SNOW LEVELS WILL DRAMATICALLY DROP TODAY...WITH SNOW ACCUMULATIONS LIKELY FOR THE CASCADE FOOTHILLS AND CASCADES. DO NOT EXPECT MORE THAN A FEW SNOW FLURRIES FOR THE LOW LANDS. THERE WILL BE A BREAK IN PRECIPITATION THURSDAY BEFORE A WARMER SYSTEM BRINGS RAIN AND MOUNTAIN SNOW ON FRI. WILL NEED TO MONITOR THE POTENTIAL FOR A WINTRY MIX AT SOME LOW ELEVATION LOCATIONS FRI MORNING. AN UPPER LEVEL RIDGE WILL SET UP OVER THE NE PAC LATE IN THE WEEK...WITH SEVERAL SYSTEMS PUSHING OVER THE TOP OF THE RIDGE THROUGH EARLY NEXT WEEK. && ...MORNING UPDATE... A VERY WEAK FRONTAL BOUNDARY MOVED THROUGH THE REGION EARLY THIS MORNING...WITH LITTLE IMPACT OTHER THAN SOME AREAS OF DRIZZLE. THE DRIZZLE DID MANAGE TO ACCUMULATE TO A FEW HUNDREDTHS OF AN INCH IN A FEW LOCATIONS. THIS INITIAL FRONT HAS NOW PUSHED SOUTH OF OUR FCST AREA FOR THE MOST PART...ALTHOUGH SOME DRIZZLE MAY BE CONTINUING OVER THE LANE COUNTY CASCADES OVER THE NEXT HOUR OR SO. ANOTHER ROUND OF PRECIPITATION WILL BE MAKING ITS WAY INTO THE NORTHERN TIER OF OUR CWA LATER THIS MORNING...THEN PUSHING SOUTH THROUGH THE REGION THIS AFTERNOON AND THIS EVENING. THE PREVIOUS FCST APPEARS TO BE RUNNING PRETTY MUCH ON TRACK. DID NUDGE QPF VALUES FOR THE 18Z TO 00Z TIME FRAME DOWN A BIT. THE PAST FEW RUNS OF THE GFS HAVE BEEN INDICATING BETTER MOISTURE AND STRONGER LIFT THAN SOME OF THE OTHER MODELS...BUT THE 12Z RUN SOMEWHAT BACKED OFF OF THE STRONGER SOLUTION. PYLE .SHORT TERM... TODAY THROUGH FRIDAY NIGHT...A WEAK FRONT WILL CONTINUE LIGHT RAIN/DRIZZLE ACROSS THE REGION THIS MORNING...WITH ACCUMULATIONS GENERALLY LESS THAN A TENTH OF AN INCH. THERE WILL BE A BRIEF BREAK IN PRECIPITATION LATE THIS MORNING BEFORE A MORE DYNAMIC DISTURBANCE BRINGS ADDITIONAL RAIN AND MOUNTAIN SNOW THIS AFTERNOON AND EVENING. THIS SECOND BOUT OF PRECIPITATION IS ASSOCIATED WITH A COLD UPPER LEVEL TROUGH THAT IS DROPPING SOUTHWARD FROM THE GULF OF ALASKA. WATER VAPOR IMAGERY SHOWS THIS TROUGH JUST OFFSHORE VICTORIA B.C. EARLY THIS MORNING. THE TROUGH HAS TRACKED SLIGHTLY MORE OVER THE OCEAN THAN THE PREVIOUS MODEL RUNS FORECASTED ALLOWING MORE MOISTURE TO BECOME AVAILABLE THAN PREVIOUSLY THOUGHT. A COLD POOL WITH 500MB TEMPERATURES NEAR -28 CELSIUS WILL MOVE OVER THE AREA THIS EVENING RESULTING IN ENOUGH INSTABILITY AND LIFT TO TAP INTO THIS MOISTURE. THEREFORE HAVE GREATER FORECAST CONFIDENCE IN SHOWERS FOR TONIGHT AND HAVE RAISED POPS. THIS TROUGH WILL MOVE FAIRLY QUICKLY THROUGH THE AREA FROM NW TO SE WITH PRECIPITATION LIMITED TO THE CASCADES AND LANE COUNTY BY MIDNIGHT TONIGHT. SNOW LEVELS IS THE GREATEST FORECAST CHALLENGE WITH THIS SYSTEM AS THEY WILL DROP DRAMATICALLY THROUGHOUT THE DAY. SNOW LEVELS NEAR 6000 FEET EARLY THIS MORNING WILL LOWER TO LESS THAN A 1000 FEET THIS EVENING. THE SHOWERS SHOULD LEAD THE COLDER AIR AND EXPECT ONLY SNOW ACCUMULATIONS FOR THE CASCADES AND CASCADE FOOTHILLS. THE HRRR MODEL WHICH HISTORICALLY HAS HANDLED THESE TYPE OF SHOWERS VERY WELL SHOWS THESE SHOWERS REACHING THE SW WA COAST AROUND 17Z (11 AM) AND THE PORTLAND METRO AREA AROUND 22Z (2 PM)...AND OVER THE CENTRAL WILLAMETTE VALLEY AROUND 4 PM. THE QUICK MOVING NATURE OF THE TROUGH WILL LIMIT RAIN/SNOW ACCUMULATIONS AND EXPECT LESS THAN 0.25 INCH OF RAIN FOR THE NORTHERN LOW LAND AREAS AND LESS THAN 0.15 INCH FOR THE SOUTHERN LOW LAND AREAS. THE CASCADES WILL LIKELY HAVE 1 TO 3 INCHES OF SNOW WITH THE CASCADE FOOTHILLS POSSIBLY MEASURING UP TO 2 INCHES. HIGH PRESSURE WILL BUILD BEHIND THE TROUGH EARLY THURSDAY MORNING. LINGERING SURFACE MOISTURE FROM THE EVENING SHOWERS COMBINED WITH LIGHT WINDS AND CLEARING SKIES SHOULD RESULT IN WIDESPREAD RADIATION FOG EARLY THURSDAY MORNING. TEMPERATURES WILL BE BELOW FREEZING WITH FREEZING FOG POSSIBLY RESULTING IN SLICK DRIVING CONDITIONS FOR THE MORNING COMMUTE. WEAK OFFSHORE WINDS SHOULD DEVELOP THU AFTERNOON AND HELP DISSIPATE THE FOG. THURSDAY WILL BE DRY AND COLD WITH INCREASING CLOUDS AHEAD OF THE NEXT FRONT. THE NEXT MORE ORGANIZED FRONT WILL APPROACH THURSDAY NIGHT. THIS FRONT HAS A LOT MORE MOISTURE WITH IT AS GFS IS FORECASTING MODELED TROPICAL PRECIPITABLE WATER VALUES NEAR AN INCH. THE DIFFERENT FORECAST MODELS VARY ON THE TIMING...AND QPF WITH THIS FRONT WITH THE NAM MODEL BEING THE MOST AGGRESSIVE. HAVE LEANED TOWARDS A BLEND OF THE GFS AND NAM FOR TIMING AND AMOUNT OF PRECIPITATION. THE AVAILABLE MOISTURE...LIFT AND APPARENT SLOW MOVING NATURE OF THIS FRONT PROVIDES GREAT POTENTIAL FOR A DECENT RAINFALL EVENT FRIDAY. SNOW LEVELS SHOULD RAPIDLY WARM AHEAD OF THIS FRONT BUT THERE IS STILL THE POSSIBILITY THAT SOME OF THE PRECIPITATION WILL OVER RUN THE WARMING LEADING TO A BRIEF PERIOD OF LOW ELEVATION SNOW. HOWEVER...SIGNIFICANT IMPACTS APPEAR UNLIKELY...AS THERE WILL LIKELY NOT BE MUCH OF A COLD POOL ON THE EAST SIDE OF THE CASCADES. WILL HAVE A BETTER IDEA OF THE DEPTH OF THE COLD AIR AND WHAT IT WILL TAKE TO ERODE THE COLD AIR AFTER THE WEDNESDAY EVENT PLAYS OUT. HARTLEY .LONG TERM...SATURDAY THROUGH TUESDAY...MADE NO CHANGES AND PREVIOUS DISCUSSION FOLLOWS...AT THIS TIME...THE EXTENDED PORTION OF THE FCST APPEARS TO ON THE MILD AND MOIST SIDE. AN UPPER LEVEL RIDGE OVER THE NE PAC IS MODELED TO STEER SEVERAL BATCHES OF MOISTURE SOUTH INTO THE PAC NW OVER THE WEEKEND AND EARLY NEXT WEEK. THIS WILL LIKELY LEAD TO PERIODS OF LIGHT RAINFALL. CONFIDENCE ON THE TIMING OF THESE SYSTEMS IS NOT HIGH AT THIS TIME. DO NOT CURRENTLY EXPECT ANY SIGNIFICANT WEATHER IMPACTS TO HOLIDAY TRAVEL AHEAD OF CHRISTMAS. PYLE && .AVIATION...WIDESPREAD IFR STRATUS AND FOG ACROSS THE REGION... WITH AREAS OF DRIZZLE. CONDITIONS NOT CHANGING MUCH THROUGH 19Z. BUT AS UPPER LEVEL SYSTEM MOVES ACROSS REGION LATER THIS AM AND EARLY AFTERNOON...CONDITIONS WILL IMPROVE TO MVFR...AND EVENTUALLY VFR TOWARDS 00Z. HIGHER TERRAIN REMAINS OBSCURED IN CLOUDS THROUGH 04Z...BUT LIKELY LONGER AGAINST THE CASCADES AND POINTS TO E AND S OF KEUG. AIR MASS WILL DRY TONIGHT...BUT STILL EXPECT WITH POCKETS OF FOG/LOW STRATUS REFORMING IN VALLEYS/BAYS AFTER 10Z. KPDX AND APPROACHES...IFR STRATUS CONTINUES THIS AM...BUT WILL SEE CLOUDS BREAK AND LIFT TO MVFR AFTER 19Z...WITH VFR EXPECTED BY 00Z OR 01Z. SHOULD REMAIN VFR THROUGH 08Z...THEN IFR STRATUS AND FOG REFORMING.ROCKEY && .MARINE...AT 9 AM...COLD FRONT WAS 125 MILES NNW OF ASTORIA AND MOVING TO THE SE. THIS FRONT WILL MOVE ACROSS THE COASTAL WATERS THIS AM. N TO NW WIND WILL INCREASE BEHIND THE FRONT WITH WINDS GUSTING 25 KT. CURRENT ADVISORIES LOOK ON TRACK SO NO CHANGES. SEAS CURRENTLY 6 TO 7 FT...BUT WILL BUILD AGAIN TODAY AS WINDS INCREASE. STILL EXPECTING SEAS OF 9 TO 11 FT LATER TODAY AND TONIGHT WITH HIGHEST OVER THE OUTER WATERS. SEAS AND WINDS EASE BACK ON THU AND THU NIGHT. BUT ANOTHER FRONT WILL BRING GUSTY WINDS...POSSIBLY GALE FORCE...AND HIGHER SEAS FOR FRI AND SAT. ROCKEY. && .PQR WATCHES/WARNINGS/ADVISORIES... OR...NONE. WA...NONE. PZ...SMALL CRAFT ADVISORY FOR WINDS AND HAZARDOUS SEAS FOR THIS AFTERNOON THROUGH THU AM ON ALL COASTAL WATERS. SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS FROM 3 PM TO 7 PM TODAY. && $$ MORE WEATHER INFORMATION ONLINE AT.. HTTP://WEATHER.GOV/PORTLAND INTERACT WITH US VIA SOCIAL MEDIA WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV WWW.TWITTER.COM/NWSPORTLAND THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1120 AM CST WED DEC 18 2013 .UPDATE... SEE UPDATED AVIATIION DISCUSSION BELOW. THE CURRENT FORECAST LOOKS GOOD OVERALL. NO MAJOR CHANGES PLANNED AT THIS TIME. BASED ON A FEW HI-RES MODELS...LOOKS LIKE ACCUMULATING SNOWFALL WILL NOT OCCUR UNTIL CLOSER TO 12Z OUT WEST. VERY DRY AIR IN THE LOWER LEVELS IN THE EASTERN CWA SHOULD KEEP THIS AREA SNOW FREE UNTIL CLOSER TO 18Z THURSDAY. && .PREVIOUS DISCUSSION... .SHORT TERM...TODAY THROUGH FRIDAY VERY GOOD AGREEMENT AMONGST THE MODELS WITH THE UPPER LEVEL AND SURFACE FEATURES TO AFFECT OUR REGION THROUGH FRIDAY. FOR TODAY...A SURFACE LOW PRESSURE AREA IN CANADA THIS MORNING WILL DESCEND SOUTHEAST ALONG A STRONG NORTHWEST TO SOUTHEAST FRONTAL ZONE BISECTING THE UPPER MIDWEST. TEMPERATURES THROUGH THIS FRONTAL ZONE EARLY THIS MORNING RANGED FROM THE TEENS BELOW ZERO IN NORTHEAST MINNESOTA TO 45 TO 50 DEGREES IN SOUTHWEST SOUTH DAKOTA. THE MUCH COLDER AIR THAT WILL AFFECT OUR REGION IS SITUATED BEHIND THIS SURFACE LOW PRESSURE AREA IN CANADA EARLY THIS MORNING. UNTIL THIS MOVES IN TONIGHT...THE CWA WILL EXPERIENCE ANOTHER ABOVE NORMAL TEMPERATURE/MILD DAY AS THE WARM FRONT OUT WEST PUSHES EAST IN ADVANCE OF THE SURFACE LOW. SOUTH TO SOUTHEAST WINDS THIS MORNING WILL TURN WEST AND NORTHWEST THROUGH THE DAY. THE ISSUE TODAY WILL BE HOW MUCH OF THE WARMER AIR ALOFT WILL BE REALIZED AT THE SURFACE AS THERE WILL BE A STRONG INVERSION ACROSS THE CWA. DUE TO THIS INVERSION...THE STRONGER WEST TO NORTHWEST WINDS OFF THE SURFACE WILL HAVE A HARD TIME MIXING DOWN. THE SNOW COVER HAS ALSO DIMINISHED SOME ACROSS THE CWA OVER THE LAST FEW DAYS RANGING GENERALLY FROM 1 TO 4 INCHES. HIGH RH ON TSCTS AND CLOUDS ON SATELLITE SHOWS THAT THE AREA SHOULD BE COVERED BY AN EXPANSIVE DECK OF MID AND HIGH LEVEL CLOUDS THROUGH THE DAY...INHIBITING SURFACE HEATING. TEMPERATURES EARLY THIS MORNING ACROSS THE CWA WERE ALREADY IN THE UPPER TEENS TO MID 20S WITH 50S OFF THE SURFACE ACROSS THE CWA. THUS...DO EXPECT THE REGION TO WARM INTO THE MID 30S TO THE MID 40S WITH SOME UPPER 40S FAR SOUTHWEST IN THE CWA BY LATE THIS AFTERNOON MELTING MORE SNOW...ESPECIALLY SOUTHWEST IN THE CWA. AS THE SURFACE LOW PRESSURE AREA PASSES BY...A STRONG ARCTIC FRONT WILL DROP ACROSS THE REGION TONIGHT. THIS WILL BRING BLUSTERY NORTH TO NORTHEAST WINDS ALONG WITH A BIG FALL IN TEMPERATURES TONIGHT. EXPECT LOWS TONIGHT IN THE SINGLE DIGITS AND LOWER TEENS ACROSS THE CWA. THURSDAY WILL REMAIN VERY COLD WITH LITTLE IF ANY RISE IN TEMPERATURES THROUGH THE DAY. THE OTHER ISSUE FOR LATER TONIGHT THROUGH THURSDAY EVENING WILL BE THE LIGHT SNOW DEVELOPING. SHORT WAVE ENERGY DROPPING IN FROM THE NORTHWEST ALONG WITH THE WARM AIR RIDING OVER THE ARCTIC AIR AND RR UPPER LEVEL JET SUPPORT WILL BRING LIGHT SNOW INTO THE NORTHWEST CWA LATER TONIGHT. THIS LIGHT SNOW WILL DEVELOP SOUTH AND THEN EAST INTO THURSDAY. THE BEST CHANCES OF LIGHT SNOW AND DECENT ACCUMULATIONS WILL REMAIN FROM MOBRIDGE TO PIERRE AND THEN EAST OVER TO MILLER AND TO WATERTOWN WITH 1 TO 3 INCHES POSSIBLE. WITH DRIER ARCTIC AIR PUSHING IN ALONG WITH LESS LIFT...THE SNOW AND ACCUMULATIONS ARE EXPECTED TO BE LIGHTER FROM ABERDEEN TO SISSETON TO WHEATON MAYBE AN INCH OR LESS. THE OTHER ISSUE WILL BE THE BLUSTERY NORTH TO NORTHEAST WINDS DEVELOPING WITH THE STRONG CAA AND A TIGHTENING SURFACE PRESSURE GRADIENT. COULD SEE WINDS OF 20 TO 30 MPH DEVELOPING WHICH WILL BRING SOME BLOWING SNOW AND FALLING WIND CHILLS. THE LIGHT SNOW WILL MOVE OUT...WINDS WILL FALL OFF QUICKLY AND SKIES WILL CLEAR THURSDAY NIGHT AS SURFACE HIGH PRESSURE SETTLES OVER THE REGION. WITH THE NEW SNOW COVER...LIGHT WINDS AND CLEAR SKIES...TEMPERATURES WILL FALL TO BELOW ZERO ACROSS ALL OF THE CWA WITH MAYBE SOME TEENS BELOW ZERO IF CONDITIONS ARE RIGHT. WITH WINDS TURNING SOUTH BEHIND THE EXITING SURFACE HIGH PRESSURE AREA ON FRIDAY...TEMPERATURES WILL HAVE A LONG WAY TO GO WITH WEAK SURFACE WAA. WITH THE NEW SNOW COVER AND MOSTLY SUNNY SKIES...TEMPERATURES WILL STRUGGLE TO MAKE IT TO 10 DEGREES IN THE EASTERN CWA WITH 15 TO AROUND 20 DEGREES OUT WEST. .LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY THE PERIOD OPENS WITH AN UPPER TROUGH SITTING OVER THE REGION. THE UPPER FLOW FLATTENS SLIGHTLY ON MONDAY BEFORE ANOTHER TROF SHIFTS IN ON TUESDAY. MONDAY NIGHT/TUESDAY MORNING A COLD FRONT MOVES THROUGH THE PLAINS. EARLY TUESDAY THERE MAY BE ENOUGH MIXING AHEAD OF THE FRONT TO POP THE TEMPERATURES UP INTO THE 20S...BUT IF THE GFS TIMING IS CORRECT TEMPS WILL THEN FALL THROUGH THE DAY. THE ECMWF IS A LITTLE SLOWER AND WOULD GIVE SD A SLIGHTLY LONGER REPRIEVE FROM THE ANTICIPATED WELL BELOW NORMAL TEMPS FORECAST FOR THE EXTENDED. THERE ARE NO WELL DEFINED CHANCES OF PRECIP DURING THE EXTENDED. SOME CAA SHORTWAVE SNOW SHOWERS ARE POSSIBLE AT VARIOUS TIMES BUT FORECASTER CONFIDENCE WOULD BE VERY LOW IN TRYING TO PIN DOWN ANY EXACT TIMING OR LOCATION. THEREFORE STUCK WITH ALLBLEND AND ITS MOSTLY DRY CONSENSUS. && .AVIATION... 18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE REST OF THE DAYLIGHT HOURS. HOWEVER AN APPROACHING ARCTIC FRONT SHOULD BRING A MIX OF MVFR/IFR CIGS WITH IT FROM NORTH TO SOUTH OVER THE REGION TNT. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...SD SHORT TERM...MOHR LONG TERM...WISE AVIATION...TDK WEATHER.GOV/ABERDEEN