Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 02/17/14


AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
622 AM EST SAT FEB 15 2014 .SYNOPSIS... THE LATEST LOW PRESSURE SYSTEM WILL QUICKLY SLIDE EAST OFF THE COAST TODAY...BUT NOT BEFORE IT BRINGS ANOTHER ROUND OF SNOW TO THE REGION. HIGH PRESSURE WILL THEN BE THE DOMINANT FEATURE IN THE REGIONAL WEATHER PATTERN THROUGH MONDAY...FOLLOWED BY FAST MOVING BUT RELATIVELY WEAK FRONTAL SYSTEMS ON TUESDAY AND WEDNESDAY. A STRONGER WARM FRONT AND ASSOCIATED LOW PRESSURE WILL AFFECT THE AREA THURSDAY NIGHT INTO FRIDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AN AREA OF LOW PRESSURE WILL MOVE ACRS NC THIS MRNG THEN NEWD OFF THE ATLC CST. IT WILL RAPIDLY INTENSIFY WELL OFF THE CST AS IT MOVS TWD THE CANADIAN MARITIMES BY SUN MRNG. AS THE LOW MOVES ON BY, IT WILL BRING SOME PRECIP WITH IT. LATEST RADAR SHOWED SOME SNOW ACRS WRN SECTIONS OF THE AREA ALREADY THIS MRNG WITH BOTH KRDG AND KABE REPORTING SNOW. THE GUID IS HAVING SOME DISAGREEMENT AS TO HOW FAST IT PUSHES EAST, WITH MOST IN AGREEMENT THAT IT DOESN`T GET TO THE I-95 CORRIDOR UNTIL AT LEAST AROUND DAYBREAK. THERE ARE ALSO SOME QUESTIONS AS TO HOW MUCH QPF WE WILL SEE, WITH THE HRRR AND ECMWF ON THE LOWER END AND THE SREF AND GFS A BIT HIGHER. FROM THE I-95 CORRIDOR S AND E, THERE IS ALSO THE QUESTION OF TEMPS AND PRECIP TYPE AS TEMPS ARE FCST TO GET ABV FREEZING DURG THE DAY SO THERE SHOULD AT LEAST BE SOME MIXING AND CHANGING DURG THE DAY TODAY. THEREFORE, WILL BE KEEPING ACCUMS ABOUT THE SAME AND NOT BE MAKING ANY CHANGES TO THE ADVYS. HOWEVER, IT SEEMS THAT THIS WINTER VIRTUALLY EVERY SYS HAS OVERPERFORMED, SO IF THIS ONE DOES, THERE MAY NEED TO BE A SEWD MVMT OF ADVYS, BUT CERTAINLY THIS IS A MORE MARGINAL EVENT DUE TO TIME OF YEAR, TIME OF DAY AND TEMPS. TEMPS ARE A BIT WARMER THAN ORIGINALLY FCST ACRS THE ERN SHORE AND SRN DEL SO HAVE CHANGED PRECIP TYPE TO RAIN OR MIX IN THESE AREAS FOR NOW. ALSO PUSHED BACK ONSET TIME OF PRECIP S AND E OF THE I-95 CORRIDOR. THE HRRR SEEMS TO BE HANDLING THIS QUITE WELL SO WENT MORE IN LINE WITH ITS FCST. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/... PRECIP SHOULD BE ALL BUT OVER OR COMING TO AN END AT THE START OF THE PD AND HIGH PRES WILL BUILD IN FROM THE W. THE PGRAD BETWEEN THE AFOREMENTIONED HIGH AND THE INTENSIFYING LOW WILL BE QUITE STRONG AND EXPECT GUSTY NW WIND TO DEVELOP. THIS WILL MAKE A COLD NIGHT FEEL EVEN COLDER. WIND COULD GUST UPWARDS OF 25 TO 30 MPH AND THE SKY WILL GRADUALLY CLEAR. && .LONG TERM /SUNDAY THROUGH FRIDAY/... IN THE WAKE OF TODAY`S LOW...HIGH PRESSURE AT THE SURFACE AND RIDGING ALOFT WILL START TO BUILD IN. THERE IS ONE EXCEPTION ON SUNDAY AFTERNOON...BOTH THE GFS AND NAM SHOW WEAK POSITIVE PRESSURE ADVECTION AT THE 1.5PV LEVEL ACROSS E CENTRAL PA INTO NW NJ. THIS LOOKS TO BE ASSOCIATED WITH A SMALL EMBEDDED UPPER LEVEL TROUGH. THE WINDOW OF LIFT IS LIMITED TO JUST A FEW HOURS SUNDAY AFTERNOON...AND WITH NORTHERLY FLOW...THERE IS LIMITED MOISTURE. STILL THERE IS A BRIEF WINDOW OF OPPORTUNITY FOR SOME SNOW. DUE TO THE BRIEF WINDOW OF OPPORTUNITY...DO NOT ANTICIPATE MUCH ADDITIONAL ACCUMULATION AT THIS TIME. THE CONTINENTAL POLAR AIR MASS REMAINS IN PLACE THROUGH AT LEAST MONDAY...LIMITING...AT LEAST FOR NOW...SIGNIFICANT MELTING OF THE SNOWPACK OVER THE REGION. CONSIDERING THIS...HAVE FOLLOWED THE TREND OF PREVIOUS SHIFTS IN UNDERCUTTING GUIDANCE FOR MAX TEMPERATURES DUE TO THE SNOWPACK FOR MOST OF THE REGION. THE FIRST SIGN OF THE WARMER PATTERN SHIFT COMES WITH THE SYSTEM MONDAY NIGHT INTO TUESDAY. THOUGH ANY PRECIPITATION WITH THIS SYSTEM SHOULD INITIALLY BEGIN AS SNOW...A WEAK WARM FRONT SHOULD LIFT AS FAR NORTH AS THE DELMARVA AREA...SO AT LEAST THE SOUTHERN HALF OF OUR REGION MAY SEE A BRIEF CHANGE OVER TO RAIN BEFORE THE PRECIPITATION ENDS TUESDAY AFTERNOON. THEN COMES THE REALLY EXCITING PART OF THE FORECAST...WE SHOULD SEE A PAIR OF WARM FRONTS...ONE ON WEDNESDAY...ANOTHER ONE THURSDAY...BRINGING WARMER CONDITIONS TO THE REGION. IN BOTH CASES...MOST OF THE PRECIPITATION WE EXPECT WITH THESE SYSTEMS SHOULD BE IN THE WARM SECTOR...MEANING WE WOULD EXPECT TO SEE MOSTLY RAIN. GIVEN THE HIGH LIQUID CONTENT OF THE SNOW PACK...STILL UNDERCUT GUIDANCE MAX T FOR THE DELAWARE RIVER VALLEY AND LOCATIONS NORTHWEST OF THERE ON WEDNESDAY...AND UNDERCUT GUIDANCE IN THE POCONOS AND THE LEHIGH VALLEY...WHERE CURRENT SNOW DEPTHS ARE ABOVE 20 INCHES...THROUGH THE END OF THE WEEK. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... LTST RADAR IMAGERY SHOWED A BAND OF SNOW OVER THE NRN AND WRN AREAS. THIS SNOW DROPPED KRDG DOWN FAIRLY QUICKLY AS IT MOVED BY BUT THEY HAVE RETURNED TO VFR CIGS BUT MVFR VSBY NOW THAT IT HAS PASSED. KABE REMAINS MVFR AND SOME IFR IS NOT OUT OF THE QUESTION UNTIL IT MOVES BY THEM. ALL OTHER SITES REMAIN VFR. IT IS EXPECTED THEY WILL REMAIN VFR UNTIL IMPACTED BY PRECIP LATER THIS MRNG. ALG THE I-95 CORRIDOR, THAT SHUD BE AROUND DAYBREAK. THE LATEST GUID INDICATES THAT ONCE A SITE GOES DOWN THEY SHUD STAY DOWN, BUT BASED UPON WHAT IS BEING OBSERVED SO FAR TONIGHT, CONFIDENCE IS LOW ON THAT. THERE WILL CERTAINLY BE PERIODS OF REDUCED CIGS/VSBYS BUT ITS PSBL THERE COULD BE SOME BREAKS AS WELL. FROM THE I-95 CORRIDOR S AND E PRECIP COULD MIX WITH OR CHANGE TO RAIN AS WELL DURING THE DAY AS TEMPS CLIMB ABV FREEZING. BY EVENING, MOST IF NOT ALL OF THE PRECIP IS OVER AND CONDS SHUD RETURN TO VFR. THEN THE NEXT ISSUE IS A STRONG AND GUSTY NW WIND WHICH WILL DEVELOP THE WIND CUD GUST TO 30 KTS OVERNIGHT. OUTLOOK... SUNDAY...GENERALLY VFR. A FEW LIGHT SHSN WILL BE POSSIBLE MAINLY NW OF KABE. MONDAY...GENERALLY VFR THROUGH THE DAY. MONDAY NIGHT AND TUESDAY...MVFR AND OCCASIONAL IFR IN SN THROUGH TUESDAY MORNING. PRECIPITATION MAY BRIEFLY CHANGE TO RA IN THE AFTERNOON BEFORE ENDING...WITH A RETURN TO VFR CONDITIONS. WEDNESDAY...GENERALLY VFR WITH SOME MVFR CEILINGS POSSIBLE IN RA DURING THE DAY WEDNESDAY. && .MARINE... AN AREA OF LOW PRESSURE WILL MOVE ACRS NC THIS MRNG THEN OFF THE ATLC CST AS IT MOVES NEWD TWD THE CAN MARITIMES BY SUN MRNG. THE LOW WILL RAPIDLY INTENSIFY AS IT MOVES TWD CANADA. THE PRESSURE GRADIENT BETWEEN THIS LOW AND HIGH PRESSURE THAT MOVES IN BEHIND IT WILL BECOME QUITE STRONG AND A GUSTY NW WIND IS EXPECTED TO DEVELOP BY LATE AFTN. THEREFORE, THE GALE WATCH IS BEING REPLACED BY A GALE WRNG FOR ALL MARINE ZONES AND IT WILL BE IN EFFECT THRU 11Z. OUTLOOK... SUNDAY...SCA CONDITIONS EXPECTED FOR MUCH OF THE DAY...DECREASING BELOW SCA BY LATE SUNDAY NIGHT. MONDAY THROUGH WEDNESDAY...SUB-SCA CONDITIONS EXPECTED. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR PAZ054- 055-060>062-101>106. NJ...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NJZ001- 007>009. DE...NONE. MD...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR MDZ008. MARINE...GALE WARNING FROM 4 PM THIS AFTERNOON TO 6 AM EST SUNDAY FOR ANZ430-431-450>455. && $$ SYNOPSIS...JOHNSON NEAR TERM...NIERENBERG SHORT TERM...NIERENBERG LONG TERM...JOHNSON AVIATION...JOHNSON/NIERENBERG MARINE...JOHNSON/NIERENBERG
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
408 AM EST SAT FEB 15 2014 .SYNOPSIS... THE LATEST LOW PRESSURE SYSTEM WILL QUICKLY SLIDE EAST OFF THE COAST TODAY...BUT NOT BEFORE IT BRINGS ANOTHER ROUND OF SNOW TO THE REGION. HIGH PRESSURE WILL THEN BE THE DOMINANT FEATURE IN THE REGIONAL WEATHER PATTERN THROUGH MONDAY...FOLLOWED BY FAST MOVING BUT RELATIVELY WEAK FRONTAL SYSTEMS ON TUESDAY AND WEDNESDAY. A STRONGER WARM FRONT AND ASSOCIATED LOW PRESSURE WILL AFFECT THE AREA THURSDAY NIGHT INTO FRIDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AN AREA OF LOW PRESSURE WILL MOVE ACRS NC THIS MRNG THEN NEWD OFF THE ATLC CST. IT WILL RAPIDLY INTENSIFY WELL OFF THE CST AS IT MOVS TWD THE CANADIAN MARITIMES BY SUN MRNG. AS THE LOW MOVES ON BY, IT WILL BRING SOME PRECIP WITH IT. LATEST RADAR SHOWED SOME SNOW ACRS WRN SECTIONS OF THE AREA ALREADY THIS MRNG WITH BOTH KRDG AND KABE REPORTING SNOW. THE GUID IS HAVING SOME DISAGREEMENT AS TO HOW FAST IT PUSHES EAST, WITH MOST IN AGREEMENT THAT IT DOESN`T GET TO THE I-95 CORRIDOR UNTIL AT LEAST AROUND DAYBREAK. THERE ARE ALSO SOME QUESTIONS AS TO HOW MUCH QPF WE WILL SEE, WITH THE HRRR AND ECMWF ON THE LOWER END AND THE SREF AND GFS A BIT HIGHER. FROM THE I-95 CORRIDOR S AND E, THERE IS ALSO THE QUESTION OF TEMPS AND PRECIP TYPE AS TEMPS ARE FCST TO GET ABV FREEZING DURG THE DAY SO THERE SHOULD AT LEAST BE SOME MIXING AND CHANGING DURG THE DAY TODAY. THEREFORE, WILL BE KEEPING ACCUMS ABOUT THE SAME AND NOT BE MAKING ANY CHANGES TO THE ADVYS. HOWEVER, IT SEEMS THAT THIS WINTER VIRTUALLY EVERY SYS HAS OVERPERFORMED, SO IF THIS ONE DOES, THERE MAY NEED TO BE A SEWD MVMT OF ADVYS, BUT CERTAINLY THIS IS A MORE MARGINAL EVENT DUE TO TIME OF YEAR, TIME OF DAY AND TEMPS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/... PRECIP SHOULD BE ALL BUT OVER OR COMING TO AN END AT THE START OF THE PD AND HIGH PRES WILL BUILD IN FROM THE W. THE PGRAD BETWEEN THE AFOREMENTIONED HIGH AND THE INTENSIFYING LOW WILL BE QUITE STRONG AND EXPECT GUSTY NW WIND TO DEVELOP. THIS WILL MAKE A COLD NIGHT FEEL EVEN COLDER. WIND COULD GUST UPWARDS OF 25 TO 30 MPH AND THE SKY WILL GRADUALLY CLEAR. && .LONG TERM /SUNDAY THROUGH FRIDAY/... IN THE WAKE OF TODAY`S LOW...HIGH PRESSURE AT THE SURFACE AND RIDGING ALOFT WILL START TO BUILD IN. THERE IS ONE EXCEPTION ON SUNDAY AFTERNOON...BOTH THE GFS AND NAM SHOW WEAK POSITIVE PRESSURE ADVECTION AT THE 1.5PV LEVEL ACROSS E CENTRAL PA INTO NW NJ. THIS LOOKS TO BE ASSOCIATED WITH A SMALL EMBEDDED UPPER LEVEL TROUGH. THE WINDOW OF LIFT IS LIMITED TO JUST A FEW HOURS SUNDAY AFTERNOON...AND WITH NORTHERLY FLOW...THERE IS LIMITED MOISTURE. STILL THERE IS A BRIEF WINDOW OF OPPORTUNITY FOR SOME SNOW. DUE TO THE BRIEF WINDOW OF OPPORTUNITY...DO NOT ANTICIPATE MUCH ADDITIONAL ACCUMULATION AT THIS TIME. THE CONTINENTAL POLAR AIR MASS REMAINS IN PLACE THROUGH AT LEAST MONDAY...LIMITING...AT LEAST FOR NOW...SIGNIFICANT MELTING OF THE SNOWPACK OVER THE REGION. CONSIDERING THIS...HAVE FOLLOWED THE TREND OF PREVIOUS SHIFTS IN UNDERCUTTING GUIDANCE FOR MAX TEMPERATURES DUE TO THE SNOWPACK FOR MOST OF THE REGION. THE FIRST SIGN OF THE WARMER PATTERN SHIFT COMES WITH THE SYSTEM MONDAY NIGHT INTO TUESDAY. THOUGH ANY PRECIPITATION WITH THIS SYSTEM SHOULD INITIALLY BEGIN AS SNOW...A WEAK WARM FRONT SHOULD LIFT AS FAR NORTH AS THE DELMARVA AREA...SO AT LEAST THE SOUTHERN HALF OF OUR REGION MAY SEE A BRIEF CHANGE OVER TO RAIN BEFORE THE PRECIPITATION ENDS TUESDAY AFTERNOON. THEN COMES THE REALLY EXCITING PART OF THE FORECAST...WE SHOULD SEE A PAIR OF WARM FRONTS...ONE ON WEDNESDAY...ANOTHER ONE THURSDAY...BRINGING WARMER CONDITIONS TO THE REGION. IN BOTH CASES...MOST OF THE PRECIPITATION WE EXPECT WITH THESE SYSTEMS SHOULD BE IN THE WARM SECTOR...MEANING WE WOULD EXPECT TO SEE MOSTLY RAIN. GIVEN THE HIGH LIQUID CONTENT OF THE SNOW PACK...STILL UNDERCUT GUIDANCE MAX T FOR THE DELAWARE RIVER VALLEY AND LOCATIONS NORTHWEST OF THERE ON WEDNESDAY...AND UNDERCUT GUIDANCE IN THE POCONOS AND THE LEHIGH VALLEY...WHERE CURRENT SNOW DEPTHS ARE ABOVE 20 INCHES...THROUGH THE END OF THE WEEK. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/... LTST RADAR IMAGERY SHOWED A BAND OF SNOW OVER THE NRN AND WRN AREAS. THIS SNOW DROPPED KRDG DOWN FAIRLY QUICKLY AS IT MOVED BY BUT THEY HAVE RETURNED TO VFR CIGS BUT MVFR VSBY NOW THAT IT HAS PASSED. KABE REMAINS MVFR AND SOME IFR IS NOT OUT OF THE QUESTION UNTIL IT MOVES BY THEM. ALL OTHER SITES REMAIN VFR. IT IS EXPECTED THEY WILL REMAIN VFR UNTIL IMPACTED BY PRECIP LATER THIS MRNG. ALG THE I-95 CORRIDOR, THAT SHUD BE AROUND DAYBREAK. THE LATEST GUID INDICATES THAT ONCE A SITE GOES DOWN THEY SHUD STAY DOWN, BUT BASED UPON WHAT IS BEING OBSERVED SO FAR TONIGHT, CONFIDENCE IS LOW ON THAT. THERE WILL CERTAINLY BE PERIODS OF REDUCED CIGS/VSBYS BUT ITS PSBL THERE COULD BE SOME BREAKS AS WELL. FROM THE I-95 CORRIDOR S AND E PRECIP COULD MIX WITH OR CHANGE TO RAIN AS WELL DURING THE DAY AS TEMPS CLIMB ABV FREEZING. BY EVENING, MOST IF NOT ALL OF THE PRECIP IS OVER AND CONDS SHUD RETURN TO VFR. THEN THE NEXT ISSUE IS A STRONG AND GUSTY NW WIND WHICH WILL DEVELOP THE WIND CUD GUST TO 30 KTS OVERNIGHT. OUTLOOK... SUNDAY...GENERALLY VFR. A FEW LIGHT SHSN WILL BE POSSIBLE MAINLY NW OF KABE. MONDAY...GENERALLY VFR THROUGH THE DAY. MONDAY NIGHT AND TUESDAY...MVFR AND OCCASIONAL IFR IN SN THROUGH TUESDAY MORNING. PRECIPITATION MAY BRIEFLY CHANGE TO RA IN THE AFTERNOON BEFORE ENDING...WITH A RETURN TO VFR CONDITIONS. WEDNESDAY...GENERALLY VFR WITH SOME MVFR CEILINGS POSSIBLE IN RA DURING THE DAY WEDNESDAY. && .MARINE... AN AREA OF LOW PRESSURE WILL MOVE ACRS NC THIS MRNG THEN OFF THE ATLC CST AS IT MOVES NEWD TWD THE CAN MARITIMES BY SUN MRNG. THE LOW WILL RAPIDLY INTENSIFY AS IT MOVES TWD CANADA. THE PRESSURE GRADIENT BETWEEN THIS LOW AND HIGH PRESSURE THAT MOVES IN BEHIND IT WILL BECOME QUITE STRONG AND A GUSTY NW WIND IS EXPECTED TO DEVELOP BY LATE AFTN. THEREFORE, THE GALE WATCH IS BEING REPLACED BY A GALE WRNG FOR ALL MARINE ZONES AND IT WILL BE IN EFFECT THRU 11Z. OUTLOOK... SUNDAY...SCA CONDITIONS EXPECTED FOR MUCH OF THE DAY...DECREASING BELOW SCA BY LATE SUNDAY NIGHT. MONDAY THROUGH WEDNESDAY...SUB-SCA CONDITIONS EXPECTED. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR PAZ054- 055-060>062-101>106. NJ...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NJZ001- 007>009. DE...NONE. MD...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR MDZ008. MARINE...GALE WARNING FROM 4 PM THIS AFTERNOON TO 6 AM EST SUNDAY FOR ANZ430-431-450>455. && $$ SYNOPSIS...JOHNSON NEAR TERM...NIERENBERG SHORT TERM...NIERENBERG LONG TERM...JOHNSON AVIATION...JOHNSON/NIERENBERG MARINE...JOHNSON/NIERENBERG
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
638 AM EST SAT FEB 15 2014 .SYNOPSIS... A FRONT WILL CROSS THE REGION LATE TONIGHT...WHICH WILL BRING A PERIOD OF SHOWERS FOLLOWED BY WINDY CONDITIONS SATURDAY. FAIR WEATHER EXPECTED SUNDAY AND MONDAY. A WEAK FRONT WILL APPROACH THE REGION TUESDAY. A WARMING TREND IS EXPECTED NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... COLD FRONT MOVING EAST OF THE MIDLANDS AT 11Z. AREA OF SHOWERS MOVING TO THE NORTHEAST OF CAE. SHOWERS IN THE NORTH MIDLANDS/PEE DEE EARLY THEN DECREASING CLOUDINESS THIS MORNING AS UPPER LEVEL TROUGH MOVES EAST AND SURFACE LOW MOVES NORTHEAST OFFSHORE NORTH CAROLINA. WINDS BEGINNING TO INCREASE UPSTREAM ACROSS GEORGIA WITH GUSTS 20 TO 30 KNOTS. WINDY CONDITIONS EXPECTED TO INCREASE ACROSS THE AREA AS SURFACE PRESSURE GRADIENT TIGHTENS. WEAK COLD ADVECTION BUT WITH CLEARING SKIES AND PLENTY OF SUN TEMPERATURES WILL ONLY BE A CATEGORY OR SO COOLER THAN TODAY. THE WINDS WILL BE THE MAIN FOCUS WITH A TIGHT PRESSURE GRADIENT BETWEEN THE DEEPENING LOW OFFSHORE AND HIGH PRESSURE BUILDING IN FROM THE WEST. LAKE WIND ADVISORY FROM 7 AM THROUGH 5 PM TO ACCOUNT FOR THE STRONG WINDS. THE POTENTIAL FOR A WIND ADVISORY EXISTS AS THE UPPER SYSTEM BECOMES A BIT NEGATIVELY TILTED AND THERE WILL BE SOME DOWNSLOPING FLOW. LATEST LAMP AND RAP GUIDANCE SUGGESTS WINDS GUSTS AROUND 30 KTS...SO WILL HOLD OFF ON WIND ADVISORY. THE SIGNIFICANT WINDS ON MAY IMPEDE THE ICE STORM CLEAN UP IN THE SOUTHERN MIDLANDS AND CENTRAL SAVANNAH RIVER AREA. HIGH TEMPERATURES SHOULD RANGE FROM THE UPPER 40S TO AROUND 50 NORTHERN MIDLANDS TO MID 50S SOUTHEASTERN MIDLANDS. && .SHORT TERM /SUNDAY THROUGH MONDAY/... SOME CLOUDS LATE TONIGHT AND EARLY SUNDAY ASSOCIATED WITH WEAK TROUGH BUT AIR MASS WILL BE DRY. GUIDANCE TEMPERATURES MAINLY IN THE MID TO UPPER 20S...MAY BE TOO LOW DUE TO CLOUDS. TEMPERATURES MODERATING ON SUNDAY WITH HIGH PRESSURE ACROSS THE AREA AND DOWNSLOPE FLOW. MAX TEMPERATURES IN THE LOW TO MID 50S NORTH TO THE LOW 60S CSRA. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... UPPER LEVEL FLOW WILL BECOME ZONAL THROUGH MID WEEK...WITH UPPER GROGGINESS DEVELOPING TO OUR WEST BY LATE WEEK. A FRONT WILL APPROACH THE REGION TUESDAY...THEN STALL AND LIFT NORTH AS A WARM FRONT THROUGH LATE WEEK...PROVIDING A SLIGHT CHANCE OF SHOWERS. UPPER HEIGHT RISES OVER THE SE CONUS...AND S TO SW LOW LEVEL FLOW AHEAD OF ANOTHER APPROACHING FRONT...WILL PROVIDE WARM TEMPERATURES MID TO LATE WEEK. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... MVFR CONDITIONS AT THE TAF SITES IMPROVING TO VFR FROM 13Z THROUGH THE END OF THE PERIOD. COLD FRONT QUICKLY MOVING EAST OF THE TAF SITES AND WILL MOVE OFFSHORE OVER THE NEXT COUPLE OF HOURS. WINDS HAVE BEGUN TO INCREASE AND BECOME GUSTY AS THE PRESSURE GRADIENT TIGHTENS BEHIND THE FRONT. BY 13Z WINDS WILL HAVE BECOME WESTERLY AROUND 18 KNOTS WITH GUSTS TO 28 KNOTS...THEN SLOWLY VEER TO NORTHWESTERLY AND SUBSIDE THROUGH THE AFTERNOON HOURS WITH GUSTS CEASING BY 23Z. FROM 16/02Z THROUGH THE END OF THE PERIOD WINDS WILL BE LIGHT AND VARIABLE. WITH DRIER AIR MOVING INTO THE AREA CLOUDS WILL ALSO DIMINISH THROUGH THE AFTERNOON. EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION EXPECTED SUNDAY MORNING THROUGH WEDNESDAY. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...LAKE WIND ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR SCZ015- 016-018-020>022-025>031-035>038-041. GA...LAKE WIND ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR GAZ040- 063>065-077. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
151 AM EST SAT FEB 15 2014 .SYNOPSIS... A FRONT WILL CROSS THE REGION LATE TONIGHT...WHICH WILL BRING A PERIOD OF SHOWERS FOLLOWED BY WINDY CONDITIONS SATURDAY. FAIR WEATHER EXPECTED SUNDAY AND MONDAY. A WEAK FRONT WILL APPROACH THE REGION TUESDAY. A WARMING TREND IS EXPECTED NEXT WEEK. && .NEAR TERM /THROUGH TODAY/... STRONG SHORT WAVE TROUGH OVER WEST GEORGIA AT 06Z. COLD FRONT ASSOCIATED WITH FAST MOVING/CLIPPER TYPE SYSTEM APPROACHING THE REGION FROM THE WEST EARLY THIS MORNING. STRONG HEIGHT FALLS COMBINED WITH THE FORECAST AREA FALLING WITHIN THE FAVORED LEFT EXIT REGION OF THE UPPER JET WILL BRING STRONG UPWARD VERTICAL MOTION OVER THE AREA DURING THE 06Z-12Z TIME FRAME. LATEST REGIONAL RADAR SHOWING RAIN MOVING ACROSS CSRA/PIEDMONT...WILL SPREAD ACROSS MIDLANDS MAINLY BEFORE DAWN. CATEGORICAL POPS BEFORE 12Z. CONFIDENCE IS HIGH MEASURABLE PRECIPITATION WILL BE OBSERVED...ALTHOUGH OVERALL PRECIPITATION AMOUNTS WILL BE LIMITED BY INITIAL DRY AIR IN PLACE AND THE SPEED OF THIS SYSTEM. GENERALLY EXPECTING AROUND A TENTH TO UP TO 0.25 INCHES OF RAINFALL. LATEST MESOSCALE MODELS SUGGEST RAIN WILL EXIT REGION BEFORE 15Z AT THE LATEST. SO CUT POPS BACK AFTER 12Z...WITH DECREASING CLOUDS AS LOW PRESSURE SYSTEM MOVES OFF TO THE NORTHEAST. SOME WEAK COLD ADVECTION EXPECTED ON SATURDAY BUT WITH CLEARING SKIES AND PLENTY OF SUN TEMPERATURES WILL ONLY BE A CATEGORY OR SO COOLER THAN TODAY. THE WINDS WILL BE THE MAIN FOCUS ON SATURDAY WITH A TIGHT PRESSURE GRADIENT BETWEEN THE DEEPENING LOW OFFSHORE AND HIGH PRESSURE BUILDING IN FROM THE WEST. LAKE WIND ADVISORY FROM 7 AM THROUGH 5 PM TO ACCOUNT FOR THE STRONG WINDS. THE POTENTIAL FOR A WIND ADVISORY EXISTS AS THE UPPER SYSTEM BECOMES A BIT NEGATIVELY TILTED AND THERE WILL BE SOME DOWNSLOPING FLOW. LATEST LAMP AND RAP GUIDANCE SUGGESTS WINDS GUSTS AROUND 30 KTS...SO WILL HOLD OFF ON WIND ADVISORY. THE SIGNIFICANT WINDS ON SATURDAY MAY IMPEDE THE ICE STORM CLEAN UP IN THE SOUTHERN MIDLANDS AND CENTRAL SAVANNAH RIVER AREA. HIGH TEMPERATURES SHOULD RANGE FROM THE UPPER 40S TO AROUND 50 NORTHERN MIDLANDS TO MID 50S SOUTHEASTERN MIDLANDS. && .SHORT TERM /TONIGHT THROUGH MONDAY/... SOME CLOUDS LATE TONIGHT AND EARLY SUNDAY ASSOCIATED WITH WEAK TROUGH BUT AIR MASS WILL BE DRY. GUIDANCE TEMPERATURES MAINLY IN THE MID TO UPPER 20S...MAY BE TOO LOW DUE TO CLOUDS. TEMPERATURES MODERATING ON SUNDAY WITH HIGH PRESSURE ACROSS THE AREA AND DOWNSLOPE FLOW. MAX TEMPERATURES IN THE LOW TO MID 50S NORTH TO THE LOW 60S CSRA. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... UPPER LEVEL FLOW WILL BECOME ZONAL THROUGH MID WEEK...WITH UPPER GROGGINESS DEVELOPING TO OUR WEST BY LATE WEEK. A FRONT WILL APPROACH THE REGION TUESDAY...THEN STALL AND LIFT NORTH AS A WARM FRONT THROUGH LATE WEEK...PROVIDING A SLIGHT CHANCE OF SHOWERS. UPPER HEIGHT RISES OVER THE SE CONUS...AND S TO SW LOW LEVEL FLOW AHEAD OF ANOTHER APPROACHING FRONT...WILL PROVIDE WARM TEMPERATURES MID TO LATE WEEK. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... MVFR CONDITIONS MOVING INTO THE TAF SITES...WITH IMPROVING CONDITIONS AFTER 12Z. FAST MOVING SYSTEM CURRENTLY JUST WEST OF THE TAF SITES WILL SPREAD MVFR AND RAIN SHOWERS INTO THE TAF SITES BY 07Z...08Z IN OGB. SYSTEM WILL BE EXITING EASTWARD AROUND 12Z WITH CONDITIONS IMPROVING TO VFR. MAIN CONCERN THROUGH THE PERIOD WILL BE WINDS WHICH WILL BECOME SOUTHWESTERLY AROUND 10 KNOTS WITH GUSTS TO 17 KNOTS AS THE RAIN MOVES INTO THE AREA...THEN FURTHER INCREASE WESTERLY TO AROUND 18 KNOTS WITH GUSTS TO 27 KNOTS AROUND 12Z AS THE PRESSURE GRADIENT TIGHTENS ON THE BACKSIDE OF THE SYSTEM. WINDS WILL SLOWLY BEGIN TO SUBSIDE DURING THE AFTERNOON AND EVENING HOURS...BECOMING LIGHT AND VARIABLE BY 16/02Z. EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION EXPECTED SUNDAY MORNING THROUGH WEDNESDAY. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...LAKE WIND ADVISORY FROM 7 AM THIS MORNING TO 5 PM EST THIS AFTERNOON FOR SCZ015-016-018-020>022-025>031-035>038-041. GA...LAKE WIND ADVISORY FROM 7 AM THIS MORNING TO 5 PM EST THIS AFTERNOON FOR GAZ040-063>065-077. && $$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
216 PM CST Sat Feb 15 2014 ...Updated long term discussion... .SHORT TERM...(Today and tonight) ISSUED AT 123 AM CST SAT FEB 15 2014 Today: Pretty interesting temperature forecast for today. A lee low with an associated warm front will clip the southern part of the forecast area of responsibility during the afternoon. Here, very warm 850 hPa temperatures of 18-20C & downslope plume will be pretty close to the Colorado and Oklahoma state borders. The tail end of the HRRR is also latching on to this in the reflection of a sfc thermal gradient across far southwest Kansas. Think that mid 70sF will be a distinct possibility by Elkhart. Elsewhere, an approaching cold front will move across portions of southwest Kansas today. As seen with yesterday, there will be considerable mixing and think that the NAM is under-doing this and the low level thermal gradient. Will call for a gradient of low 60sF across much of the forecast area with mid 60sF to low 70sF across far western Kansas. Tonight: By this evening, high pressure will ridge across the outlook area with fairly light winds. There will be weak upslope flow across western Kansas with weak warm air advection in the low levels on the backside of the departing high. The NAM/NSSL WRF/SREF probabilities show fog potential for Sunday morning. Not very confident in spatial arrangement of fog, but have added it in the wx grids in case these three models are correct. Future shifts can adjust as necessary. Dewpoints won`t be very high, but there could be a radiational fog environment with an inversion and light sfc winds. Overnight minimums will be higher as fog and mid to high level cloud cover lingers. Saw no reason to deviate from previous forecast, which is widespread low 30s for lows. .LONG TERM...(Sunday night through Saturday) ISSUED AT 216 PM CST SAT FEB 15 2014 The 12z medium range models are all similar in showing a fairly zonal upper flow pattern with fast moving shortwave troughs moving east over the country in the flow. The first wave is progged to move out over the Plains Sunday night with another wave progged to move out around Wednesday night into Thursday. The models tend to keep the strongest upper level energy, and consequently any significant precipitation associated with these waves confined to the northern Plains. On Wednesday night the models show that the low level moisture return makes a brief show in central Kansas but it gets rapidly shunted off to the east. The 12z ECMWF is more in line with the GFS and not quite as amplified as its previous run, which suggested a rain changing over to snow. Not overly impressed with precipitation chances but given the uncertainty and in deference to my neighboring WFOs, will keep some slight chance pops for rain or a rain/snow mix over central and south central Kansas from Wednesday night into Thursday. Late in the week on into next weekend, the models are indicating that the upper level ridge along the west coast of North America will undergo some amplification. As this occurs, the models show a deep trough developing over the central Plains during the weekend. This would bring about another period of colder than normal temperatures to western Kansas through the weekend into early the following week. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) ISSUED AT 1118 AM CST SAT FEB 15 2014 Winds will shift to more of a northerly direction today with wind speeds around 15 knots gusting to over 20 knots at times. Wind speeds then decrease to around 10 knots by early this evening. VFR conditions will prevail with only a few high clouds. && .PRELIMINARY POINT TEMPS/POPS... DDC 31 61 39 57 / 0 0 0 0 GCK 32 62 39 56 / 0 0 0 0 EHA 32 69 41 58 / 0 0 0 0 LBL 32 66 41 58 / 0 0 0 0 HYS 30 57 36 56 / 0 0 0 0 P28 32 59 40 59 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Sugden LONG TERM...Gerard AVIATION...Hovorka_42
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1042 AM MST SAT FEB 15 2014 .UPDATE... ISSUED AT 951 AM MST SAT FEB 15 2014 JUST COMPLETED AN UPDATE. PROBLEMATIC TEMPERATURE FORECAST TODAY. MODELS NOT HANDLING SURFACE PATTERN WELL AS COLD FRONT HAS SURGED SOUTH FASTER AND WITH COLDER AIR THAN ADVERTISED. THE LATEST TWO VERSIONS OF THE RAP HAVE CAUGHT ONTO THE WIND AND LAYOUT OF THE TEMPERATURES. SOME LOCATIONS MAY END UP REMAINING STEADY OR EVEN SLOWLY FALLING FOR THE REST OF THE TODAY. SO USED IT AT AS A BASIS FOR THIS UPDATE. WILL KEEP WATCHING TRENDS OF COURSE BUT WOULD NOT BE SURPRISED IF HAVE TO DO ANOTHER UPDATE. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 228 AM MST SAT FEB 15 2014 ZONAL FLOW ALOFT OVER THE UNITED STATES KEEPS THE PATTERN PROGRESSIVE THROUGH THE SHORT TERM PERIOD WITH GENERALLY WARM AND DRY CONDITIONS EXPECTED. FORECAST CONCERN IS THE POSSIBILITY OF STRONGER WINDS SUNDAY AND SUNDAY NIGHT. THE UPPER RIDGE CURRENTLY IN PLACE OVER THE WESTERN UNITED STATES TRANSLATES EAST ACROSS THE ROCKIES TODAY AND THE HIGH PLAINS TONIGHT AHEAD OF A THROUGH THAT MOVES THROUGH THEW INTERMOUNTAIN WEST ON SUNDAY AND ACROSS THE HIGH PLAINS REGION SUNDAY NIGHT. WESTERLY FLOW REMAINS IN PLACE MONDAY AND MONDAY NIGHT. AT THE SURFACE...BREEZY SOUTHWEST WINDS WILL TURN NORTHWEST BEHIND A COLD FRONT THAT MOVES THROUGH THE FORECAST AREA BY MID DAY TODAY. A COOLER AREA OF HIGH PRESSURE MOVES QUICKLY THROUGH THE FORECAST AREA OVERNIGHT WITH WINDS TURNING BACK TO THE SOUTHWEST BY SUNDAY MORNING AS A PREFRONTAL TROUGH DEEPENS ALONG THE FRONT RANGE AHEAD OF THE APPROACHING UPPER TROUGH. SURFACE WINDS TURN NORTHWEST AGAIN WITH THE PASSAGE OF ANOTHER COLD FRONT SUNDAY EVENING. MODELS ARE HINTING AT THE POSSIBILITY OF SOME LIGHT PRECIPITATION ACROSS THE FAR NORTH AND NORTHEAST SECTIONS OF THE FORECAST AREA SUNDAY NIGHT...BUT THE BULK OF THE QPF SHOWING UP REMAINS NORTH OF THE FORECAST AREA AND HAVE DECIDED TO LEAVE ANY POSSIBILITY OF PRECIPITATION OUT OF THE FORECAST FOR NOW. SURFACE WINDS RETURN QUICKLY TO THE SOUTHWEST AS ANOTHER LEE TROUGH DEEPENS ALONG THE FRONT RANGE IN RESPONSE TO THE WESTERLY FLOW ALOFT. THIS SURFACE TROUGH MOVES EAST MONDAY NIGHT WITH GENERALLY WESTERLY WINDS ACROSS THE FORECAST AREA. BREEZY AND GUSTY SOUTHWEST WINDS ARE EXPECTED AHEAD OF THE COLD FRONT ON SUNDAY WITH BREEZY AND GUSTY NORTHWEST WINDS BEHIND THE FRONT SUNDAY NIGHT. HAVE HELD OFF ON ANY WIND HIGHLIGHTS AT THIS TIME SINCE MODEL WIND SPEEDS ARE CURRENTLY BELOW ADVISORY THRESHOLDS AND TRANSITION THE FORECAST AREA PRETTY QUICKLY...BUT MAY NEED TO ISSUE A WIND HIGHLIGHT IF WIND SPEEDS LOOK LIKE THEY WILL BE STRONGER OR ARE SUSTAINED FOR A LONGER TIME PERIOD THAN CURRENTLY ADVERTISED. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 228 AM MST SAT FEB 15 2014 UPPER LEVEL FLOW WILL BE WESTERLY IN A ZONAL FLOW PATTERN OVER THE TRI STATE AREA FOR TUESDAY...RESULTING IN QUIET WEATHER WITH FAIR CONDITIONS. A RIDGE WILL BUILD FROM THE WEST AND WILL MOVE INTO THE HIGH PLAINS WEDNESDAY. A TROUGH WILL DEVELOP AND MOVE THROUGH THE FORECAST AREA WEDNESDAY NIGHT IN ASSOCIATION WITH A CLOSED UPPER LEVEL LOW FORECAST TO MOVE ACROSS THE NORTH CENTRAL PLAINS. A SECOND PUSH OF COLDER AIR ALOFT WILL MOVE INTO THE REGION FRIDAY NIGHT INTO SATURDAY MORNING. NUMEROUS FRONTAL PASSAGES WILL TAKE PLACE DURING THE EXTENDED FORECAST. A WEAK COLD FRONT WILL MOVE THROUGH THE HIGH PLAINS TUESDAY. GUIDANCE SUGGESTS SURFACE TEMPERATURES WILL REACH THE LOWER 60S. HOWEVER COLD AIR ADVECTION AT 850 MB WITH TEMPERATURES BETWEEN 8 AND 12 CELSIUS...ALONG WITH NORTHWEST WINDS AT THE SURFACE...SUGGEST TEMPERATURES CLOSER TO THE MIDDLE 50S. LOWERED TEMPERATURES A BIT FROM WHAT INIT PROCEDURE PLACED IN THE FORECAST. REGARDLESS OF TEMPERATURES...WEATHER IS EXPECTED TO BE QUIET FOR TUESDAY. A WARM FRONT WILL PASS OVER THE HIGH PLAINS WEDNESDAY WITH PLENTY OF WARM AIR ADVECTION AT 850 MB AND THE SURFACE. WITH 850 TEMPERATURES FROM GUIDANCE BETWEEN 12 AND 15 CELSIUS...TEMPERATURES AT THE SURFACE WILL MORE LIKELY REACH THE UPPER 50S TO LOW 60S IN THE AFTERNOON. THE WEATHER COULD BECOME MORE INTERESTING WEDNESDAY NIGHT AS A COLD FRONT APPROACHES THE AREA FROM THE NORTHWEST. MODEL GUIDANCE DIFFERS AS TO THE TIMING OF THE FRONTAL PASSAGE...BUT SLIGHT CHANCES FOR PRECIPITATION ARE POSSIBLE FOR THE AREA. 1000 TO 500 MB MODEL THICKNESS DIFFER SOMEWHAT AS TO PLACEMENT OF THE RAIN/SNOW LINE... BUT CONSENSUS GENERALLY INDICATES WARM SECTOR WILL START OVER THE AREA BEFORE THE COLD SECTOR MOVES INTO THE AREA THURSDAY MORNING. THEREFORE IF PRECIPITATION DOES OCCUR...IT WILL PROBABLY START OUT AS RAIN OVERNIGHT WEDNESDAY AND TRANSITION INTO A MIXTURE OF SNOW AND RAIN SOMETIME THURSDAY MORNING. TEMPERATURES WILL STAY RIGHT AROUND AVERAGE FOR THURSDAY AND FRIDAY...WITH HIGHS REACHING THE UPPER 40S TO LOWER 50S. ANOTHER COLD FRONT WILL PUSH THROUGH THE HIGH PLAINS FRIDAY NIGHT...WHICH WILL DECREASE HIGH TEMPERATURES INTO THE UPPER 30S TO LOWER 40S FOR SATURDAY. SOME LIGHT SNOW SHOWERS MIGHT OCCUR WITH THE FRONTAL PASSAGE...BUT NO SIGNIFICANT SNOW ACCUMULATIONS ARE EXPECTED AT THIS TIME. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1039 AM MST SAT FEB 15 2014 VARIABLE AND CHANGING CONDITIONS ACROSS THE AREA...ESPECIALLY NEAR KGLD. STRONG COLD FRONT HAS SURGED SOUTH. FOR KGLD...THIS WILL CREATE NEAR MVFR OR MVFR CONDITIONS THROUGH THE MIDDLE OF THE AFTERNOON. OTHERWISE THE REMAINDER OF THE PERIOD FOR KGLD AND THE ENTIRE PERIOD AT KMCK WILL BE VFR. WINDS WILL GUSTY OUT OF THE NORTH FOR THE REST OF THE AFTERNOON. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...BULLER SHORT TERM...LOCKHART LONG TERM...99 AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1121 AM CST Sat Feb 15 2014 ...Updated aviation section... .SHORT TERM...(Today and tonight) ISSUED AT 123 AM CST SAT FEB 15 2014 Today: Pretty interesting temperature forecast for today. A lee low with an associated warm front will clip the southern part of the forecast area of responsibility during the afternoon. Here, very warm 850 hPa temperatures of 18-20C & downslope plume will be pretty close to the Colorado and Oklahoma state borders. The tail end of the HRRR is also latching on to this in the reflection of a sfc thermal gradient across far southwest Kansas. Think that mid 70sF will be a distinct possibility by Elkhart. Elsewhere, an approaching cold front will move across portions of southwest Kansas today. As seen with yesterday, there will be considerable mixing and think that the NAM is under-doing this and the low level thermal gradient. Will call for a gradient of low 60sF across much of the forecast area with mid 60sF to low 70sF across far western Kansas. Tonight: By this evening, high pressure will ridge across the outlook area with fairly light winds. There will be weak upslope flow across western Kansas with weak warm air advection in the low levels on the backside of the departing high. The NAM/NSSL WRF/SREF probabilities show fog potential for Sunday morning. Not very confident in spatial arrangement of fog, but have added it in the wx grids in case these three models are correct. Future shifts can adjust as necessary. Dewpoints won`t be very high, but there could be a radiational fog environment with an inversion and light sfc winds. Overnight minimums will be higher as fog and mid to high level cloud cover lingers. Saw no reason to deviate from previous forecast, which is widespread low 30s for lows. .LONG TERM...(Sunday through Friday) ISSUED AT 314 AM CST SAT FEB 15 2014 On Sunday, there will be a nearly zonal flow over the plains, with a cold front approaching from the north. It should be mostly sunny with mainly high cirrus clouds passing overhead. Winds will be from the southwest and the pressure gradient will tighten up in the afternoon as the cold front encroaches. Winds should start out from the southwest at 5 to 15 mph in the morning, but increase from the southwest at 15 to 20 mph with gusts to near 30 mph in the afternoon. It should warm up nicely into the upper 50s to lower 60s, but the winds will still be noticeable. Sunday night could be windier than Sunday, as the cold front moves through. South winds will shift to the northwest at 15 to 30 mph, gusting as high as 40 mph. A wind advisory may be needed for parts of Sunday night and Monday morning. Those strong winds will continue into Monday morning, bringing the same 20 mph to 30 mph gusting to 40 mph range to that area east of a Scott City to Meade line. By late Monday, winds should be from the west at around 10 mph. The cold front will bring down max temps somewhat, into the middle 50s. Tuesday will respond to a wind shift back to the southwest, with mostly sunny skies and maximum temperatures in the middle to upper 60s. A zonal flow will return aloft Tuesday into Wednesday. Wednesday should be the warmest day overall, with lower 60s expected north of I-70, and maxes around 70F along the Oklahoma border. A large upper level trough will approach from the west Wednesday night, bringing first a slight chance for rain to our western CWA, basically west of a Hays to Liberal line, and then a chance for light snow after midnight Wednesday night. By Thursday morning, there will be a cold front dragging through southwest Kansas, the precip may be either rain or snow Thursday morning. By afternoon, the lower layers should warm up enough to change any precipitation back to rain, east of a Scott City to Garden City to near Liberal line. Right now, I do not think anyone will get more than light rain or light snow. We will go into a zonal flow aloft by Friday, and then to a southwest upper level flow by Saturday. Friday will be a moderating day with highs in the mid 50s to lower 60s, then clouds and shallow cold air spilling south from the northern plains will dip maximum temperatures back into the lower to middle 40s by Saturday, which will be closer to climatological highs. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) ISSUED AT 1118 AM CST SAT FEB 15 2014 Winds will shift to more of a northerly direction today with wind speeds around 15 knots gusting to over 20 knots at times. Wind speeds then decrease to around 10 knots by early this evening. VFR conditions will prevail with only a few high clouds. && .PRELIMINARY POINT TEMPS/POPS... DDC 62 31 61 39 / 0 0 0 0 GCK 63 32 62 39 / 0 0 0 0 EHA 76 32 69 41 / 0 0 0 0 LBL 69 32 66 41 / 0 0 0 0 HYS 61 30 57 36 / 0 0 0 0 P28 61 32 59 40 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Sugden LONG TERM...Burke AVIATION...Hovorka_42
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1006 AM MST SAT FEB 15 2014 .UPDATE... ISSUED AT 951 AM MST SAT FEB 15 2014 JUST COMPLETED AN UPDATE. PROBLEMATIC TEMPERATURE FORECAST TODAY. MODELS NOT HANDLING SURFACE PATTERN WELL AS COLD FRONT HAS SURGED SOUTH FASTER AND WITH COLDER AIR THAN ADVERTISED. THE LATEST TWO VERSIONS OF THE RAP HAVE CAUGHT ONTO THE WIND AND LAYOUT OF THE TEMPERATURES. SOME LOCATIONS MAY END UP REMAINING STEADY OR EVEN SLOWLY FALLING FOR THE REST OF THE TODAY. SO USED IT AT AS A BASIS FOR THIS UPDATE. WILL KEEP WATCHING TRENDS OF COURSE BUT WOULD NOT BE SURPRISED IF HAVE TO DO ANOTHER UPDATE. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 228 AM MST SAT FEB 15 2014 ZONAL FLOW ALOFT OVER THE UNITED STATES KEEPS THE PATTERN PROGRESSIVE THROUGH THE SHORT TERM PERIOD WITH GENERALLY WARM AND DRY CONDITIONS EXPECTED. FORECAST CONCERN IS THE POSSIBILITY OF STRONGER WINDS SUNDAY AND SUNDAY NIGHT. THE UPPER RIDGE CURRENTLY IN PLACE OVER THE WESTERN UNITED STATES TRANSLATES EAST ACROSS THE ROCKIES TODAY AND THE HIGH PLAINS TONIGHT AHEAD OF A THROUGH THAT MOVES THROUGH THEW INTERMOUNTAIN WEST ON SUNDAY AND ACROSS THE HIGH PLAINS REGION SUNDAY NIGHT. WESTERLY FLOW REMAINS IN PLACE MONDAY AND MONDAY NIGHT. AT THE SURFACE...BREEZY SOUTHWEST WINDS WILL TURN NORTHWEST BEHIND A COLD FRONT THAT MOVES THROUGH THE FORECAST AREA BY MID DAY TODAY. A COOLER AREA OF HIGH PRESSURE MOVES QUICKLY THROUGH THE FORECAST AREA OVERNIGHT WITH WINDS TURNING BACK TO THE SOUTHWEST BY SUNDAY MORNING AS A PREFRONTAL TROUGH DEEPENS ALONG THE FRONT RANGE AHEAD OF THE APPROACHING UPPER TROUGH. SURFACE WINDS TURN NORTHWEST AGAIN WITH THE PASSAGE OF ANOTHER COLD FRONT SUNDAY EVENING. MODELS ARE HINTING AT THE POSSIBILITY OF SOME LIGHT PRECIPITATION ACROSS THE FAR NORTH AND NORTHEAST SECTIONS OF THE FORECAST AREA SUNDAY NIGHT...BUT THE BULK OF THE QPF SHOWING UP REMAINS NORTH OF THE FORECAST AREA AND HAVE DECIDED TO LEAVE ANY POSSIBILITY OF PRECIPITATION OUT OF THE FORECAST FOR NOW. SURFACE WINDS RETURN QUICKLY TO THE SOUTHWEST AS ANOTHER LEE TROUGH DEEPENS ALONG THE FRONT RANGE IN RESPONSE TO THE WESTERLY FLOW ALOFT. THIS SURFACE TROUGH MOVES EAST MONDAY NIGHT WITH GENERALLY WESTERLY WINDS ACROSS THE FORECAST AREA. BREEZY AND GUSTY SOUTHWEST WINDS ARE EXPECTED AHEAD OF THE COLD FRONT ON SUNDAY WITH BREEZY AND GUSTY NORTHWEST WINDS BEHIND THE FRONT SUNDAY NIGHT. HAVE HELD OFF ON ANY WIND HIGHLIGHTS AT THIS TIME SINCE MODEL WIND SPEEDS ARE CURRENTLY BELOW ADVISORY THRESHOLDS AND TRANSITION THE FORECAST AREA PRETTY QUICKLY...BUT MAY NEED TO ISSUE A WIND HIGHLIGHT IF WIND SPEEDS LOOK LIKE THEY WILL BE STRONGER OR ARE SUSTAINED FOR A LONGER TIME PERIOD THAN CURRENTLY ADVERTISED. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 228 AM MST SAT FEB 15 2014 UPPER LEVEL FLOW WILL BE WESTERLY IN A ZONAL FLOW PATTERN OVER THE TRI STATE AREA FOR TUESDAY...RESULTING IN QUIET WEATHER WITH FAIR CONDITIONS. A RIDGE WILL BUILD FROM THE WEST AND WILL MOVE INTO THE HIGH PLAINS WEDNESDAY. A TROUGH WILL DEVELOP AND MOVE THROUGH THE FORECAST AREA WEDNESDAY NIGHT IN ASSOCIATION WITH A CLOSED UPPER LEVEL LOW FORECAST TO MOVE ACROSS THE NORTH CENTRAL PLAINS. A SECOND PUSH OF COLDER AIR ALOFT WILL MOVE INTO THE REGION FRIDAY NIGHT INTO SATURDAY MORNING. NUMEROUS FRONTAL PASSAGES WILL TAKE PLACE DURING THE EXTENDED FORECAST. A WEAK COLD FRONT WILL MOVE THROUGH THE HIGH PLAINS TUESDAY. GUIDANCE SUGGESTS SURFACE TEMPERATURES WILL REACH THE LOWER 60S. HOWEVER COLD AIR ADVECTION AT 850 MB WITH TEMPERATURES BETWEEN 8 AND 12 CELSIUS...ALONG WITH NORTHWEST WINDS AT THE SURFACE...SUGGEST TEMPERATURES CLOSER TO THE MIDDLE 50S. LOWERED TEMPERATURES A BIT FROM WHAT INIT PROCEDURE PLACED IN THE FORECAST. REGARDLESS OF TEMPERATURES...WEATHER IS EXPECTED TO BE QUIET FOR TUESDAY. A WARM FRONT WILL PASS OVER THE HIGH PLAINS WEDNESDAY WITH PLENTY OF WARM AIR ADVECTION AT 850 MB AND THE SURFACE. WITH 850 TEMPERATURES FROM GUIDANCE BETWEEN 12 AND 15 CELSIUS...TEMPERATURES AT THE SURFACE WILL MORE LIKELY REACH THE UPPER 50S TO LOW 60S IN THE AFTERNOON. THE WEATHER COULD BECOME MORE INTERESTING WEDNESDAY NIGHT AS A COLD FRONT APPROACHES THE AREA FROM THE NORTHWEST. MODEL GUIDANCE DIFFERS AS TO THE TIMING OF THE FRONTAL PASSAGE...BUT SLIGHT CHANCES FOR PRECIPITATION ARE POSSIBLE FOR THE AREA. 1000 TO 500 MB MODEL THICKNESS DIFFER SOMEWHAT AS TO PLACEMENT OF THE RAIN/SNOW LINE... BUT CONSENSUS GENERALLY INDICATES WARM SECTOR WILL START OVER THE AREA BEFORE THE COLD SECTOR MOVES INTO THE AREA THURSDAY MORNING. THEREFORE IF PRECIPITATION DOES OCCUR...IT WILL PROBABLY START OUT AS RAIN OVERNIGHT WEDNESDAY AND TRANSITION INTO A MIXTURE OF SNOW AND RAIN SOMETIME THURSDAY MORNING. TEMPERATURES WILL STAY RIGHT AROUND AVERAGE FOR THURSDAY AND FRIDAY...WITH HIGHS REACHING THE UPPER 40S TO LOWER 50S. ANOTHER COLD FRONT WILL PUSH THROUGH THE HIGH PLAINS FRIDAY NIGHT...WHICH WILL DECREASE HIGH TEMPERATURES INTO THE UPPER 30S TO LOWER 40S FOR SATURDAY. SOME LIGHT SNOW SHOWERS MIGHT OCCUR WITH THE FRONTAL PASSAGE...BUT NO SIGNIFICANT SNOW ACCUMULATIONS ARE EXPECTED AT THIS TIME. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 430 AM MST SAT FEB 15 2014 CONDITIONS ARE EXPECTED TO REMAIN VFR THROUGH THE TAF PERIOD AT MCK AND GLD. SOUTHWEST WINDS WILL TURN NORTHWEST AND BECOME GUSTY BETWEEN 15Z-18Z AS A COLD FRONT MOVES THROUGH THE CENTRAL HIGH PLAINS REGION. SKY COVER WILL INCREASE AND CEILINGS WILL LOWER AS THE FRONT MOVES THROUGH...WITH DECREASING SKY COVER AND HIGHER CLOUD BASES OVERNIGHT. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...BULLER SHORT TERM...LOCKHART LONG TERM...99 AVIATION...LOCKHART
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
535 AM CST Sat Feb 15 2014 ...Updated for the aviation discussion... .SHORT TERM...(Today and tonight) ISSUED AT 123 AM CST SAT FEB 15 2014 Today: Pretty interesting temperature forecast for today. A lee low with an associated warm front will clip the southern part of the forecast area of responsibility during the afternoon. Here, very warm 850 hPa temperatures of 18-20C & downslope plume will be pretty close to the Colorado and Oklahoma state borders. The tail end of the HRRR is also latching on to this in the reflection of a sfc thermal gradient across far southwest Kansas. Think that mid 70sF will be a distinct possibility by Elkhart. Elsewhere, an approaching cold front will move across portions of southwest Kansas today. As seen with yesterday, there will be considerable mixing and think that the NAM is under-doing this and the low level thermal gradient. Will call for a gradient of low 60sF across much of the forecast area with mid 60sF to low 70sF across far western Kansas. Tonight: By this evening, high pressure will ridge across the outlook area with fairly light winds. There will be weak upslope flow across western Kansas with weak warm air advection in the low levels on the backside of the departing high. The NAM/NSSL WRF/SREF probabilities show fog potential for Sunday morning. Not very confident in spatial arrangement of fog, but have added it in the wx grids in case these three models are correct. Future shifts can adjust as necessary. Dewpoints won`t be very high, but there could be a radiational fog environment with an inversion and light sfc winds. Overnight minimums will be higher as fog and mid to high level cloud cover lingers. Saw no reason to deviate from previous forecast, which is widespread low 30s for lows. .LONG TERM...(Sunday through Friday) ISSUED AT 314 AM CST SAT FEB 15 2014 On Sunday, there will be a nearly zonal flow over the plains, with a cold front approaching from the north. It should be mostly sunny with mainly high cirrus clouds passing overhead. Winds will be from the southwest and the pressure gradient will tighten up in the afternoon as the cold front encroaches. Winds should start out from the southwest at 5 to 15 mph in the morning, but increase from the southwest at 15 to 20 mph with gusts to near 30 mph in the afternoon. It should warm up nicely into the upper 50s to lower 60s, but the winds will still be noticeable. Sunday night could be windier than Sunday, as the cold front moves through. South winds will shift to the northwest at 15 to 30 mph, gusting as high as 40 mph. A wind advisory may be needed for parts of Sunday night and Monday morning. Those strong winds will continue into Monday morning, bringing the same 20 mph to 30 mph gusting to 40 mph range to that area east of a Scott City to Meade line. By late Monday, winds should be from the west at around 10 mph. The cold front will bring down max temps somewhat, into the middle 50s. Tuesday will respond to a wind shift back to the southwest, with mostly sunny skies and maximum temperatures in the middle to upper 60s. A zonal flow will return aloft Tuesday into Wednesday. Wednesday should be the warmest day overall, with lower 60s expected north of I-70, and maxes around 70F along the Oklahoma border. A large upper level trough will approach from the west Wednesday night, bringing first a slight chance for rain to our western CWA, basically west of a Hays to Liberal line, and then a chance for light snow after midnight Wednesday night. By Thursday morning, there will be a cold front dragging through southwest Kansas, the precip may be either rain or snow Thursday morning. By afternoon, the lower layers should warm up enough to change any precipitation back to rain, east of a Scott City to Garden City to near Liberal line. Right now, I do not think anyone will get more than light rain or light snow. We will go into a zonal flow aloft by Friday, and then to a southwest upper level flow by Saturday. Friday will be a moderating day with highs in the mid 50s to lower 60s, then clouds and shallow cold air spilling south from the northern plains will dip maximum temperatures back into the lower to middle 40s by Saturday, which will be closer to climatological highs. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) ISSUED AT 530 AM CST SAT FEB 15 2014 The first concern is wind shear this morning. There is a south-southwest low level jet, just off the surface, at around 2000 ft. It is blowing nearly 40 knots at that level, while at the surface winds are southerly at only 13 knots. As that jet moves off to the east around 16z, the localized wind shear will diminish. Cirrus clouds are increasing, and cigs in the bkn200-250 range should develop by 15 to 16Z. Later this afternoon, the cirrus deck will scatter out, a cold front will move through, and winds will shift to the north at around 10kts by 21z. && .PRELIMINARY POINT TEMPS/POPS... DDC 62 31 61 39 / 0 0 0 0 GCK 63 32 62 39 / 0 0 0 0 EHA 76 32 69 41 / 0 0 0 0 LBL 69 32 66 41 / 0 0 0 0 HYS 61 30 57 36 / 0 0 0 0 P28 61 32 59 40 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Sugden LONG TERM...Burke AVIATION...Burke
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
326 AM CST Sat Feb 15 2014 ...Update for the long term discussion... .SHORT TERM...(Today and tonight) ISSUED AT 123 AM CST SAT FEB 15 2014 Today: Pretty interesting temperature forecast for today. A lee low with an associated warm front will clip the southern part of the forecast area of responsibility during the afternoon. Here, very warm 850 hPa temperatures of 18-20C & downslope plume will be pretty close to the Colorado and Oklahoma state borders. The tail end of the HRRR is also latching on to this in the reflection of a sfc thermal gradient across far southwest Kansas. Think that mid 70sF will be a distinct possibility by Elkhart. Elsewhere, an approaching cold front will move across portions of southwest Kansas today. As seen with yesterday, there will be considerable mixing and think that the NAM is under-doing this and the low level thermal gradient. Will call for a gradient of low 60sF across much of the forecast area with mid 60sF to low 70sF across far western Kansas. Tonight: By this evening, high pressure will ridge across the outlook area with fairly light winds. There will be weak upslope flow across western Kansas with weak warm air advection in the low levels on the backside of the departing high. The NAM/NSSL WRF/SREF probabilities show fog potential for Sunday morning. Not very confident in spatial arrangement of fog, but have added it in the wx grids in case these three models are correct. Future shifts can adjust as necessary. Dewpoints won`t be very high, but there could be a radiational fog environment with an inversion and light sfc winds. Overnight minimums will be higher as fog and mid to high level cloud cover lingers. Saw no reason to deviate from previous forecast, which is widespread low 30s for lows. .LONG TERM...(Sunday through Friday) ISSUED AT 314 AM CST SAT FEB 15 2014 On Sunday, there will be a nearly zonal flow over the plains, with a cold front approaching from the north. It should be mostly sunny with mainly high cirrus clouds passing overhead. Winds will be from the southwest and the pressure gradient will tighten up in the afternoon as the cold front encroaches. Winds should start out from the southwest at 5 to 15 mph in the morning, but increase from the southwest at 15 to 20 mph with gusts to near 30 mph in the afternoon. It should warm up nicely into the upper 50s to lower 60s, but the winds will still be noticeable. Sunday night could be windier than Sunday, as the cold front moves through. South winds will shift to the northwest at 15 to 30 mph, gusting as high as 40 mph. A wind advisory may be needed for parts of Sunday night and Monday morning. Those strong winds will continue into Monday morning, bringing the same 20 mph to 30 mph gusting to 40 mph range to that area east of a Scott City to Meade line. By late Monday, winds should be from the west at around 10 mph. The cold front will bring down max temps somewhat, into the middle 50s. Tuesday will respond to a wind shift back to the southwest, with mostly sunny skies and maximum temperatures in the middle to upper 60s. A zonal flow will return aloft Tuesday into Wednesday. Wednesday should be the warmest day overall, with lower 60s expected north of I-70, and maxes around 70F along the Oklahoma border. A large upper level trough will approach from the west Wednesday night, bringing first a slight chance for rain to our western CWA, basically west of a Hays to Liberal line, and then a chance for light snow after midnight Wednesday night. By Thursday morning, there will be a cold front dragging through southwest Kansas, the precip may be either rain or snow Thursday morning. By afternoon, the lower layers should warm up enough to change any precipitation back to rain, east of a Scott City to Garden City to near Liberal line. Right now, I do not think anyone will get more than light rain or light snow. We will go into a zonal flow aloft by Friday, and then to a southwest upper level flow by Saturday. Friday will be a moderating day with highs in the mid 50s to lower 60s, then clouds and shallow cold air spilling south from the northern plains will dip maximum temperatures back into the lower to middle 40s by Saturday, which will be closer to climatological highs. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) ISSUED AT 1100 PM CST FRI FEB 14 2014 Some mid to high level clouds this morning/today. Frontal system moves through with southerly winds veering northwesterly by noon or so then northerly this afternoon. Magnitudes 10-15 kt. && .PRELIMINARY POINT TEMPS/POPS... DDC 62 31 61 39 / 0 0 0 0 GCK 63 32 62 39 / 0 0 0 0 EHA 76 32 69 41 / 0 0 0 0 LBL 69 32 66 41 / 0 0 0 0 HYS 61 30 57 36 / 0 0 0 0 P28 61 32 59 40 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Sugden LONG TERM...Burke AVIATION...Sugden
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
123 AM CST Sat Feb 15 2014 ...Update to short term... .SHORT TERM...(Today and tonight) ISSUED AT 123 AM CST SAT FEB 15 2014 Today: Pretty interesting temperature forecast for today. A lee low with an associated warm front will clip the southern part of the forecast area of responsibility during the afternoon. Here, very warm 850 hPa temperatures of 18-20C & downslope plume will be pretty close to the Colorado and Oklahoma state borders. The tail end of the HRRR is also latching on to this in the reflection of a sfc thermal gradient across far southwest Kansas. Think that mid 70sF will be a distinct possibility by Elkhart. Elsewhere, an approaching cold front will move across portions of southwest Kansas today. As seen with yesterday, there will be considerable mixing and think that the NAM is under-doing this and the low level thermal gradient. Will call for a gradient of low 60sF across much of the forecast area with mid 60sF to low 70sF across far western Kansas. Tonight: By this evening, high pressure will ridge across the outlook area with fairly light winds. There will be weak upslope flow across western Kansas with weak warm air advection in the low levels on the backside of the departing high. The NAM/NSSL WRF/SREF probabilities show fog potential for Sunday morning. Not very confident in spatial arrangement of fog, but have added it in the wx grids in case these three models are correct. Future shifts can adjust as necessary. Dewpoints won`t be very high, but there could be a radiational fog environment with an inversion and light sfc winds. Overnight minimums will be higher as fog and mid to high level cloud cover lingers. Saw no reason to deviate from previous forecast, which is widespread lows 30sF for lows. .LONG TERM...(Saturday night through Friday) ISSUED AT 204 PM CST FRI FEB 14 2014 The mid to high level flow will remain mostly zonal through Tuesday, with a progressive shortwave trough passing by Monday morning. Mild weather can be expected Sunday ahead of the associated front with highs in the 50s/60s; then Monday should be just a little cooler with highs in the 50s. After a mild day Tuesday with highs in the 60s to lower 70s, along with weak lee troughing on the high plains, a longwave upper level trough is expected to develop over the high plains and Rockies by mid to late week, with strong, embedded shortwave troughs and associated cold fronts progressing across the plains. The timing and amplitude of these systems late Wednesday/Thursday and then again late Friday or early Saturday is questionable. But all the models suggest a rather progressive series of shortwave troughs, with most of the low level moisture well off to the east. There may be enough mid level moisture for a few showers or a little light snow late Wednesday night into Thursday, with high temperatures cooling back into the high 40s or lower 50s on Thursday, depending on the extent of cloud and precipitation. At this point, we are not expecting any major precipitation events through February 24th. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) ISSUED AT 1100 PM CST FRI FEB 14 2014 Some mid to high level clouds this morning/today. Frontal system moves through with southerly winds veering northwesterly by noon or so then northerly this afternoon. Magnitudes 10-15 kt. && .PRELIMINARY POINT TEMPS/POPS... DDC 62 32 61 39 / 0 0 0 0 GCK 63 33 62 39 / 0 0 0 0 EHA 76 35 69 41 / 0 0 0 0 LBL 69 34 66 41 / 0 0 0 0 HYS 61 31 57 36 / 0 0 0 0 P28 61 33 59 40 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Sugden LONG TERM...Finch AVIATION...Sugden
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
906 PM EST SUN FEB 16 2014 .UPDATE... ISSUED AT 905 PM EST SUN FEB 16 2014 TEMPERATURES ARE CRASHING THIS EVENING...ALREADY -8F AT THE OFFICE HERE IN NEGAUNEE TWP. ALTHOUGH HIGHER CLOUDS ARE MOVING INTO THE AREA FROM THE WEST...IT WILL TAKE AWHILE FOR THEM TO REACH THE EASTERN HALF OF THE FORECAST AREA. AS SUCH...LOWERED TEMPERATURES ACROSS THE ENTIRE AREA. IN FACT...WOULD NOT BE SURPRISED TO SEE TEMPS -20F ACROSS THE EAST TONIGHT. WITH THE CLOUDS MOVING INTO THE WEST...TEMPS SHOULD LEVEL OUT THERE...BUT STILL CLOSE TO ZERO OR A LITTLE BELOW. OTHERWISE...LOTS OF RADAR RETURNS IN MN...BUT IT LOOKS LIKE MOST OF IT IS VIRGA AS THERE ARE NOT MANY SFC REPORTS OF SNOW UNTIL YOU GET MUCH CLOSER TO THE FRONT IN THE DAKOTAS. COULD SEE SOME LIGHT SNOW TIED TO THE FIRST PUNCH OF WARM ADVECTION MOVING NORTHWARD LATE TONIGHT...BUT THE THOUGHT IS THAT THE BEST SNOW WILL NOT MOVE INTO THE WEST UNTIL AFT 12Z. AS SUCH...WILL LOWER POPS TONIGHT INTO EARLY MON MORNING ESPECIALLY ACROSS THE CENTRAL PART OF THE FORECAST AREA. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 418 PM EST SUN FEB 16 2014 WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL PATTERN ACROSS THE WEST AND CNTRL CONUS WITH A MID/UPPER LEVEL TROUGH AND SEVERAL EMBEDDED SHRTWVS THROUGH THE NRN ROCKIES. LINGERING CONFLUENT FLOW OVER NRN ONTARIO INTO THE NRN LAKES AND ASSOCIATED SFC ARCTIC HIGH PRESSURE HAS BROUGHT MOSTLY CLEAR SKIES TO THE REGION. VIS LOOP SHOWED MID/HIGH CLOUD SPREADING QUICKLY THROUGH MN WITH THE WAA REGIME AHEAD OF LOW PRES OVER THE WRN PLAINS. TONIGHT...CLEAR SKIES EARLY THIS EVENING SHOULD GIVE WAY TO INCREASING CLOUDS OVERNIGHT...PER MDLS RH FCST AND SATELLITE TRENDS. RADIATIONAL COOLING THIS EVENING WILL ALLOW TEMPS TO DROP QUICKLY WITH GRADUALLY RISING TEMPS OVERNIGHT FROM WEST TO EAST. OVER THE ERN CWA...WITH THE LONGER PERIOD OF CLEAR SKIES...TEMPS COULD DROP TO AROUND -10F OR EVENING COLDER. OTHERWISE...LOWS IN THE ZERO TO -5F RANGE ARE EXPECTED CENTRAL AND 0 TO 5F WEST. MONDAY...THE MODELS WERE IN RELATIVELY GOOD AGREEMENT AS THE MID LEVEL TROUGH MOVES THROUGH THE UPPER MS VALLEY AND GREAT LAKES. THE STRONGER 700-300 MB QVECTOR CONV ASSOCIATED WITH THE THE SRN SHRTWV WILL IS EXPECTED TO MOVE THROUGH SRN WI INTO SRN LOWER MI. HOWEVER...THE WEAKER QG FORCING TO THE NORTH ALONG WITH 285K-290K ISENTROPIC LIFT AHEAD OF THE TROUGH WITH 2G/KG AVAILABLE SHOULD ALSO SUPPORT MODERATE SNOWFALL ACROSS UPPER MICHIGAN. WITH THE STRONGER DYNAMICS TO THE SOUTH OF THE CWA...THE FCST LEANED MORE TOWARD THE LOWER END OF CONSENSUS QPF VALUES...MAINLY IN THE 0.25 TO 0.35 INCH RANGE...PER NAM AND REGIONAL GEM. UPWARD MOTION THE DGZ SUPPORTS SLR VALUES IN THE 15/1 TO 20/1 RANGE GIVING OVERALL SNOWFALL AMOUNTS IN THE 3 TO 6 INCH RANGE. ALTHOUGH SRLY WINDS WILL INCREASE AND BECOME GUSTY AT TIMES...BLSN IS NOT EXPECTED TO BE A SIGNIFICANT PROBLEM. A WINTER WEATHER ADVISORY WAS ISSUED TO COVER THE EXPECTED CONDITIONS. THE BEST CHANCE TO REACH OR EXCEED THE 6 INCH WARNING THRESHOLD WOULD BE OVER THE SRN CWA...BUT CONFIDENCE WAS NOT HIGH ENOUGH TO POST A WINTER STORM WARNING. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 335 PM EST SUN FEB 16 2014 A SHORTWAVE TROUGH WILL BE OVER WRN UPPER MI AT 00Z TUE AND WILL PUSH E OF THE CWA SHORTLY AFTER 06Z TUE. MOST OF THE SNOW FROM THIS SYSTEM COMES PRIOR TO 00Z TUE...SO WILL LEAVE MOST OF THE DISCUSSION OF THIS SYSTEM TO THE SHORT TERM FORECASTER. 12Z/16 GFS CONTINUES TO APPEAR TOO FAST WITH THE SYSTEM...SO STUCK WITH NON-GFS SOLUTIONS FOR POPS/QPF. MOST OF THE ADDITIONAL SNOW MON NIGHT FALLS PRIOR TO 06Z...WITH NO SNOW EXPECTED IN THE 00Z-06Z TIME PERIOD OVER FAR WRN UPPER MI TO 2 INCHES OVER THE ERN CWA. DEEP MOISTURE EXITS WITH THE SHORTWAVE LATE MON NIGHT WHILE MID/LOW LEVEL TEMPS INCREASE AS THE MID LEVEL PORTION OF A WARM FRONT MOVES IN FROM THE W. THIS TRAPS MOISTURE IN THE LOW LEVELS OVER THE ERN CWA WITH DRY AIR ABOVE THE INVERSION...WHICH LEAVES THE DGZ DRY AND SUB-INVERSION TEMPS NOT SUFFICIENT FOR ICE CRYSTAL FORMATION. THINK THERE IS A POSSIBILITY OF FREEZING DRIZZLE OVER ERN UPPER MI FOR A BRIEF PERIOD LATE MON NIGHT INTO TUE MORNING AS THE SFC PORTION OF THE WARM FRONT APPROACHES. THE CENTRAL AND WRN CWA WILL NOT SEE AS MUCH MOISTURE UNDER THE INVERSION...SO NOT AS WORRIED THERE. HOWEVER...GIVEN LACK OF SIGNIFICANT TOPOGRAPHY FOR UPSLOPE WITH THE SW WINDS OVER SCHOOLCRAFT AND LUCE COUNTIES...WILL NOT ADD FREEZING DRIZZLE TO THE FORECAST AT THIS TIME. THE REST OF TUE IS TRICKY...ESPECIALLY WITH TEMPERATURES POSSIBLY APPROACHING FREEZING FOR THE FIRST TIME IN A WHILE. A THERMAL RIDGE PASSES OVERHEAD AROUND MID DAY TUE WITH 850MB TEMPS AOA 0C IN MOST LOCATIONS...WHICH IS FAVORABLE FOR WARMER TEMPS. NEGATIVES FOR THE WARMER TEMPS ARE EASIER TO COME UP WITH...INCLUDING THE FACT THAT IT HAS BEEN QUITE COLD LATELY SO THE SNOW PACK IS VERY COLD. WE WILL HAVE FRESH SNOW FROM THE PREVIOUS EVENING THAT WILL HELP KEEP TEMPS COLD AND SFC ALBEDO LOWER. ANY WARMING POTENTIAL FROM THE NORMAL WARMER WATERS OF THE GREAT LAKES WILL BE REDUCED OR ELIMINATED DUE TO ICE COVER. UNTIL THE WARM FRONT MOVES THROUGH...THERE SHOULD BE A GOOD AMOUNT OF CLOUD COVER...WHICH WILL LIMIT WARMING. A COLD FRONT MOVES INTO THE CWA LATE TUE AFTERNOON AND TUE EVENING...BRINGING COLDER AIR AND MORE CLOUDS. IN FACT...BY 00Z WED...NWRN UPPER MI SHOULD SEE 850MB TEMPS DOWN TO -4C. ANOTHER SIGNIFICANT NEGATIVE FOR THE WARMER TEMPS IS THAT MODELS ARE SHOWING A COUPLE OF WEAK SHORTWAVES MOVING ACROSS THE NRN CWA FROM EARLY TUE AFTERNOON THROUGH TUE EVENING...WHICH WILL AT LEAST KEEP CLOUD COVER UP OVER NRN UPPER MI AND LAKE SUPERIOR AND MAY EVEN BRING SOME MINOR LIGHT SNOW /SINCE AREAS OF THE LOW AND MID LEVELS THAT WILL BE ABOVE 0C WILL BE DRY WITH SUB-ZERO WET BULB TEMPS/. CONSIDERING ALL THIS...TEMPS WILL BE VERY CONDITIONAL...WITH THE BEST CHANCES OF SEEING ABOVE FREEZING TEMPS OVER SRN UPPER MI NEAR THE WI BORDER. LEFT TEMPS SIMILAR ALONG THE WI BORDER...BUT LOWERED A COUPLE OF DEGREES OVER NRN AREAS. NO SIGNIFICANT PRECIP IS EXPECTED WED AND TEMPS WILL BE BELOW FREEZING AS MODELS CONTINUE TO INDICATE 850MB TEMPS AOB -5C AT 18Z. ANOTHER THERMAL RIDGE MOVES THROUGH WED NIGHT. A SHORTWAVE LOOKS TO MOVE INTO THE REGION LATER THU INTO THU NIGHT...BRINGING COLDER AIR FOR THE REST OF THU ALONG WITH INCREASED CLOUD COVER. AS FAR AS PRECIP IS CONCERNED...THINGS ARE A LOT MORE UNCERTAIN AS MODELS DO NOT HAVE GOOD CONTINUITY WITH THE EXACT LOCATION AND INTENSITY OF THE SHORTWAVE. AT THIS TIME...IT DOES APPEAR THE BULK OF THE SHORTWAVE ENERGY WILL GO N OF THE CWA...WITH POSSIBLY ADVISORY LEVEL SNOWFALL OVER UPPER MI. AGAIN...UNCERTAINTY IS HIGH IN THE PRECIP FORECAST FOR THIS TIME PERIOD. THEN FOR FRI THROUGH NEXT SUN...IT APPEARS THAT UPPER TROUGHING WILL DOMINATE MUCH OF THE CONUS...BRINGING A RETURN OF BELOW NORMAL TEMPERATURES. WHILE THERE IS MORE CONFIDENCE IN THE COLDER TEMPS...OVERALL CONFIDENCE IS LOW. USED GENERAL MODEL CONSENSUS FOR THIS PERIOD OF THE FORECAST. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 632 PM EST SUN FEB 16 2014 A QUIET AVIATION WEATHER EVENING WITH HIGH PRESSURE IN CONTROL. LOW PRESSURE OVER THE PLAINS WILL MOVE TOWARD THE AREA TONIGHT...AND PASS ACROSS THE REGION ON MONDAY. SOUTH-SOUTHEAST WINDS WILL DEVELOP AHEAD OF THE SYSTEM TONIGHT...WITH A STRONG LOW LEVEL JET POTENTIALLY CAUSING LLWS AT ALL TERMINALS AROUND SUNRISE MONDAY. SNOW ASSOCIATED WITH THE SYSTEM WILL SPREAD ACROSS THE REGION FROM W-E MONDAY MORNING...ALONG WITH IFR VSBYS. IT IS POSSIBLE THAT SITES WILL SEE LIFR VSBYS LATER TMRW MORNING WHEN THE SOUTH WINDS GUST TO 20-25KT CREATING BLSN. SNOW SHOULD DIMINISH LATE MON AFTN INTO MONDAY NIGHT. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 418 PM EST SUN FEB 16 2014 OVERALL...WINDS ARE FORECAST TO BE LESS THAN 25 KTS THROUGH THE UPCOMING WEEK. SOUTHEAST WINDS TO 30 KTS OCCUR MONDAY AND MONDAY EVENING OVER EASTERN AND NORTH CENTRAL LK SUPERIOR...BUT GALES ARE NOT EXPECTED AS MAIN SFC LOW PRESSURE PASSES OVER CNTRL AND LOWER GREAT LAKES. WINDS MAY TREND STRONGER LATE THIS WEEK AS ANOTHER LOW PRESSURE SYSTEM IMPACTS THE REGION. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 11 AM MONDAY TO 1 AM EST TUESDAY FOR MIZ006-007-014-085. WINTER WEATHER ADVISORY FROM 7 AM EST /6 AM CST/ TO 10 PM EST /9 PM CST/ MONDAY FOR MIZ001-003>005-010>013-084. WINTER WEATHER ADVISORY FROM 5 AM EST /4 AM CST/ TO 7 PM EST /6 PM CST/ MONDAY FOR MIZ002-009. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...MRD SHORT TERM...JLB LONG TERM...TITUS AVIATION...MRD MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
636 PM EST SUN FEB 16 2014 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 418 PM EST SUN FEB 16 2014 WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL PATTERN ACROSS THE WEST AND CNTRL CONUS WITH A MID/UPPER LEVEL TROUGH AND SEVERAL EMBEDDED SHRTWVS THROUGH THE NRN ROCKIES. LINGERING CONFLUENT FLOW OVER NRN ONTARIO INTO THE NRN LAKES AND ASSOCIATED SFC ARCTIC HIGH PRESSURE HAS BROUGHT MOSTLY CLEAR SKIES TO THE REGION. VIS LOOP SHOWED MID/HIGH CLOUD SPREADING QUICKLY THROUGH MN WITH THE WAA REGIME AHEAD OF LOW PRES OVER THE WRN PLAINS. TONIGHT...CLEAR SKIES EARLY THIS EVENING SHOULD GIVE WAY TO INCREASING CLOUDS OVERNIGHT...PER MDLS RH FCST AND SATELLITE TRENDS. RADIATIONAL COOLING THIS EVENING WILL ALLOW TEMPS TO DROP QUICKLY WITH GRADUALLY RISING TEMPS OVERNIGHT FROM WEST TO EAST. OVER THE ERN CWA...WITH THE LONGER PERIOD OF CLEAR SKIES...TEMPS COULD DROP TO AROUND -10F OR EVENING COLDER. OTHERWISE...LOWS IN THE ZERO TO -5F RANGE ARE EXPECTED CENTRAL AND 0 TO 5F WEST. MONDAY...THE MODELS WERE IN RELATIVELY GOOD AGREEMENT AS THE MID LEVEL TROUGH MOVES THROUGH THE UPPER MS VALLEY AND GREAT LAKES. THE STRONGER 700-300 MB QVECTOR CONV ASSOCIATED WITH THE THE SRN SHRTWV WILL IS EXPECTED TO MOVE THROUGH SRN WI INTO SRN LOWER MI. HOWEVER...THE WEAKER QG FORCING TO THE NORTH ALONG WITH 285K-290K ISENTROPIC LIFT AHEAD OF THE TROUGH WITH 2G/KG AVAILABLE SHOULD ALSO SUPPORT MODERATE SNOWFALL ACROSS UPPER MICHIGAN. WITH THE STRONGER DYNAMICS TO THE SOUTH OF THE CWA...THE FCST LEANED MORE TOWARD THE LOWER END OF CONSENSUS QPF VALUES...MAINLY IN THE 0.25 TO 0.35 INCH RANGE...PER NAM AND REGIONAL GEM. UPWARD MOTION THE DGZ SUPPORTS SLR VALUES IN THE 15/1 TO 20/1 RANGE GIVING OVERALL SNOWFALL AMOUNTS IN THE 3 TO 6 INCH RANGE. ALTHOUGH SRLY WINDS WILL INCREASE AND BECOME GUSTY AT TIMES...BLSN IS NOT EXPECTED TO BE A SIGNIFICANT PROBLEM. A WINTER WEATHER ADVISORY WAS ISSUED TO COVER THE EXPECTED CONDITIONS. THE BEST CHANCE TO REACH OR EXCEED THE 6 INCH WARNING THRESHOLD WOULD BE OVER THE SRN CWA...BUT CONFIDENCE WAS NOT HIGH ENOUGH TO POST A WINTER STORM WARNING. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 335 PM EST SUN FEB 16 2014 A SHORTWAVE TROUGH WILL BE OVER WRN UPPER MI AT 00Z TUE AND WILL PUSH E OF THE CWA SHORTLY AFTER 06Z TUE. MOST OF THE SNOW FROM THIS SYSTEM COMES PRIOR TO 00Z TUE...SO WILL LEAVE MOST OF THE DISCUSSION OF THIS SYSTEM TO THE SHORT TERM FORECASTER. 12Z/16 GFS CONTINUES TO APPEAR TOO FAST WITH THE SYSTEM...SO STUCK WITH NON-GFS SOLUTIONS FOR POPS/QPF. MOST OF THE ADDITIONAL SNOW MON NIGHT FALLS PRIOR TO 06Z...WITH NO SNOW EXPECTED IN THE 00Z-06Z TIME PERIOD OVER FAR WRN UPPER MI TO 2 INCHES OVER THE ERN CWA. DEEP MOISTURE EXITS WITH THE SHORTWAVE LATE MON NIGHT WHILE MID/LOW LEVEL TEMPS INCREASE AS THE MID LEVEL PORTION OF A WARM FRONT MOVES IN FROM THE W. THIS TRAPS MOISTURE IN THE LOW LEVELS OVER THE ERN CWA WITH DRY AIR ABOVE THE INVERSION...WHICH LEAVES THE DGZ DRY AND SUB-INVERSION TEMPS NOT SUFFICIENT FOR ICE CRYSTAL FORMATION. THINK THERE IS A POSSIBILITY OF FREEZING DRIZZLE OVER ERN UPPER MI FOR A BRIEF PERIOD LATE MON NIGHT INTO TUE MORNING AS THE SFC PORTION OF THE WARM FRONT APPROACHES. THE CENTRAL AND WRN CWA WILL NOT SEE AS MUCH MOISTURE UNDER THE INVERSION...SO NOT AS WORRIED THERE. HOWEVER...GIVEN LACK OF SIGNIFICANT TOPOGRAPHY FOR UPSLOPE WITH THE SW WINDS OVER SCHOOLCRAFT AND LUCE COUNTIES...WILL NOT ADD FREEZING DRIZZLE TO THE FORECAST AT THIS TIME. THE REST OF TUE IS TRICKY...ESPECIALLY WITH TEMPERATURES POSSIBLY APPROACHING FREEZING FOR THE FIRST TIME IN A WHILE. A THERMAL RIDGE PASSES OVERHEAD AROUND MID DAY TUE WITH 850MB TEMPS AOA 0C IN MOST LOCATIONS...WHICH IS FAVORABLE FOR WARMER TEMPS. NEGATIVES FOR THE WARMER TEMPS ARE EASIER TO COME UP WITH...INCLUDING THE FACT THAT IT HAS BEEN QUITE COLD LATELY SO THE SNOW PACK IS VERY COLD. WE WILL HAVE FRESH SNOW FROM THE PREVIOUS EVENING THAT WILL HELP KEEP TEMPS COLD AND SFC ALBEDO LOWER. ANY WARMING POTENTIAL FROM THE NORMAL WARMER WATERS OF THE GREAT LAKES WILL BE REDUCED OR ELIMINATED DUE TO ICE COVER. UNTIL THE WARM FRONT MOVES THROUGH...THERE SHOULD BE A GOOD AMOUNT OF CLOUD COVER...WHICH WILL LIMIT WARMING. A COLD FRONT MOVES INTO THE CWA LATE TUE AFTERNOON AND TUE EVENING...BRINGING COLDER AIR AND MORE CLOUDS. IN FACT...BY 00Z WED...NWRN UPPER MI SHOULD SEE 850MB TEMPS DOWN TO -4C. ANOTHER SIGNIFICANT NEGATIVE FOR THE WARMER TEMPS IS THAT MODELS ARE SHOWING A COUPLE OF WEAK SHORTWAVES MOVING ACROSS THE NRN CWA FROM EARLY TUE AFTERNOON THROUGH TUE EVENING...WHICH WILL AT LEAST KEEP CLOUD COVER UP OVER NRN UPPER MI AND LAKE SUPERIOR AND MAY EVEN BRING SOME MINOR LIGHT SNOW /SINCE AREAS OF THE LOW AND MID LEVELS THAT WILL BE ABOVE 0C WILL BE DRY WITH SUB-ZERO WET BULB TEMPS/. CONSIDERING ALL THIS...TEMPS WILL BE VERY CONDITIONAL...WITH THE BEST CHANCES OF SEEING ABOVE FREEZING TEMPS OVER SRN UPPER MI NEAR THE WI BORDER. LEFT TEMPS SIMILAR ALONG THE WI BORDER...BUT LOWERED A COUPLE OF DEGREES OVER NRN AREAS. NO SIGNIFICANT PRECIP IS EXPECTED WED AND TEMPS WILL BE BELOW FREEZING AS MODELS CONTINUE TO INDICATE 850MB TEMPS AOB -5C AT 18Z. ANOTHER THERMAL RIDGE MOVES THROUGH WED NIGHT. A SHORTWAVE LOOKS TO MOVE INTO THE REGION LATER THU INTO THU NIGHT...BRINGING COLDER AIR FOR THE REST OF THU ALONG WITH INCREASED CLOUD COVER. AS FAR AS PRECIP IS CONCERNED...THINGS ARE A LOT MORE UNCERTAIN AS MODELS DO NOT HAVE GOOD CONTINUITY WITH THE EXACT LOCATION AND INTENSITY OF THE SHORTWAVE. AT THIS TIME...IT DOES APPEAR THE BULK OF THE SHORTWAVE ENERGY WILL GO N OF THE CWA...WITH POSSIBLY ADVISORY LEVEL SNOWFALL OVER UPPER MI. AGAIN...UNCERTAINTY IS HIGH IN THE PRECIP FORECAST FOR THIS TIME PERIOD. THEN FOR FRI THROUGH NEXT SUN...IT APPEARS THAT UPPER TROUGHING WILL DOMINATE MUCH OF THE CONUS...BRINGING A RETURN OF BELOW NORMAL TEMPERATURES. WHILE THERE IS MORE CONFIDENCE IN THE COLDER TEMPS...OVERALL CONFIDENCE IS LOW. USED GENERAL MODEL CONSENSUS FOR THIS PERIOD OF THE FORECAST. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 632 PM EST SUN FEB 16 2014 A QUIET AVIATION WEATHER EVENING WITH HIGH PRESSURE IN CONTROL. LOW PRESSURE OVER THE PLAINS WILL MOVE TOWARD THE AREA TONIGHT...AND PASS ACROSS THE REGION ON MONDAY. SOUTH-SOUTHEAST WINDS WILL DEVELOP AHEAD OF THE SYSTEM TONIGHT...WITH A STRONG LOW LEVEL JET POTENTIALLY CAUSING LLWS AT ALL TERMINALS AROUND SUNRISE MONDAY. SNOW ASSOCIATED WITH THE SYSTEM WILL SPREAD ACROSS THE REGION FROM W-E MONDAY MORNING...ALONG WITH IFR VSBYS. IT IS POSSIBLE THAT SITES WILL SEE LIFR VSBYS LATER TMRW MORNING WHEN THE SOUTH WINDS GUST TO 20-25KT CREATING BLSN. SNOW SHOULD DIMINISH LATE MON AFTN INTO MONDAY NIGHT. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 418 PM EST SUN FEB 16 2014 OVERALL...WINDS ARE FORECAST TO BE LESS THAN 25 KTS THROUGH THE UPCOMING WEEK. SOUTHEAST WINDS TO 30 KTS OCCUR MONDAY AND MONDAY EVENING OVER EASTERN AND NORTH CENTRAL LK SUPERIOR...BUT GALES ARE NOT EXPECTED AS MAIN SFC LOW PRESSURE PASSES OVER CNTRL AND LOWER GREAT LAKES. WINDS MAY TREND STRONGER LATE THIS WEEK AS ANOTHER LOW PRESSURE SYSTEM IMPACTS THE REGION. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 11 AM MONDAY TO 1 AM EST TUESDAY FOR MIZ006-007-014-085. WINTER WEATHER ADVISORY FROM 7 AM EST /6 AM CST/ TO 10 PM EST /9 PM CST/ MONDAY FOR MIZ001-003>005-010>013-084. WINTER WEATHER ADVISORY FROM 5 AM EST /4 AM CST/ TO 7 PM EST /6 PM CST/ MONDAY FOR MIZ002-009. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...TITUS AVIATION...MRD MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
349 PM EST SAT FEB 15 2014 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 345 PM EST SAT FEB 15 2014 WV IMAGERY AND RUC ANALYSIS INDICATED A WELL-DEFINED UPSTREAM CLIPPER SHORTWAVE TROUGH INTO NRN MN AND ANOTHER TO THE SOUTH OVER IA. RELATIVELY STEEP 700-500 MB LAPSE RATES FROM 7.5C-8.0C/KM HAS HELPED MAXIMIZING LIFT WITH THE MODERATE 700-500 MB QVECTOR CONV AHEAD OF THE SHRTWV HAS SUPPORTED AREAS OF MODERATE SNOW FROM NRN MN INTO WRN LAKE SUPERIOR. THE SNOW ALSO FROM NRN MN INTO THE KEWEENAW ALSO HAD A CONVECTIVE APPEARANCE...PER VIS SATELLITE LOOP. OTHERWISE...CLOUDS WERE THICKENING ACROSS THE REST OF UPPER MI AS THE AREA OF SNOW FROM NEAR DLH INTO NW WI APPROACHED IWD. THE INITIAL FOCUS FOR THE HEAVIER SNOW INTO THE KEWEENAW THIS AFTERNOON WAS ALIGNED WITH 800-600 MB FGEN. HOWEVER...SATELLITE/RADAR TRENDS AND THE NAM/REGIONAL GEM SUGGEST THAT THE STRONGER FORCING WILL SLIDE THROUGH WRN AND WRN UPPER MI THIS EVENING AHEAD OF THE SHRTWV. UPSTREAM OBS AND MODELS CONSENSUS QPF OF 0.10 TO 0.15 INCH WITH THE SLR VALUES OF AROUND 20/1 WOULD GIVE SNOWFALL AMOUNTS IN THE 2 TO 3 INCH RANGE. SOME LOCAL HIGHER AMOUNTS MAY BE POSSIBLE OVER THE KEWEENAW WHERE THE DURATION OF FGEN FORCING AND LOCALLY WHERE THE CONVECTIVE NATURE OF THE SNOW SQUEEZES OUT SOME GREATER AMOUNTS. AMOUNTS OVER THE KEWEENAW WOULD LIKELY BE MUCH HIGHER BUT THE EXTENSIVE ICE COVER HAS LIMITED ANY LAKE ENHANCEMENT WITH THE LOW LEVEL ERLY FLOW. EXPECT THE SNOW TO DIMINISH QUICKLY FROM WEST TO EAST LATE THIS EVENING AS THE SHRTWV DEPARTS. HIGH PRES WILL BUILD INTO THE REGION LATE TONIGHT AND SUNDAY WITH LOW LEVEL NE FLOW. THERE MAY ALSO BE SOME LIGHT LES INTO N CNTRL UPPER MI WITH SOME MOISTURE/HEAT FLUX FROM ANY GAPS IN THE LAKE ICE COVER. LOW LEVEL MOISTURE WILL ALSO GRADUALLY DIMINISH WITH PARTLY SUNNY SKIES BY AFTERNOON. TEMPERATURES WILL REMAIN BELOW NORMAL WITH HIGHS RECOVERING INTO THE MID AND UPPER TEENS. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 345 PM EST SAT FEB 15 2014 OVERALL PATTERN IN THE LONG TERM IS INITIALLY DRIVEN BY ENERGY EJECTING OUT OF A DEEP UPPER LOW CURRENTLY OVER THE GULF OF AK. THAT UPPER LOW WILL WEAKEN SIGNIFICANTLY MON INTO TUE...WITH SOME OF THE REMAINING ENERGY BEING TRANSPORTED INTO THE WRN AND CENTRAL CONUS MID-LATE THIS WEEK WHERE MODELS INDICATE IT WILL BE DEEPENED INTO A AMPLIFIED UPPER TROUGH OVER THE PLAINS STATES. THE FIRST WAVE OF ENERGY IS SET TO MOVE THROUGH THE AREA LATE MON INTO MON NIGHT. A FEW THINGS ARE LEADING TO MODEL DISAGREEMENT ON THE STRENGTH...TRACK AND TIMING OF THIS SYSTEM...WHICH IMPACTS RELATED FIELDS SUCH AS QPF. FIRST...THE ENERGY IS STILL TIED TO THE LOW AND IS OVER THE PACIFIC...AND THEREFORE OUT OF THE BETTER UPPER LEVEL OBSERVATION NETWORK SO SAMPLING IS AT LEAST SOMEWHAT OF AN ISSUE. SECOND...AND PROBABLY THE MORE SUBSTANTIAL REASON FOR DISAGREEMENT...IS THAT THE ENERGY LOOKS TO BE SPLIT BETWEEN A NRN AND SRN SHORTWAVE...THE SOUTHERN OF WHICH IS HELPED OUT BY AN JET STREAK AND IS THE MAIN FEATURE. MODELS ARE HAVING TROUBLE /RUN TO RUN AND MODEL TO MODEL/ WITH AGREEMENT ON HOW MUCH OF THE ENERGY TO ALLOT TO EACH OF THE SHORTWAVES...ALONG WITH MOISTURE FIELDS AND SUCH. THE 12Z/15 GFS AND 00Z/15 ECMWF REPRESENT TWO OF THE EXTREMES WITH THE NRN SHORTWAVE. THE GFS IS WEAKER AND FASTER /WITH LOWER QPF TOTALS LESS THAN 0.30 INCHES/ WHILE THE ECMWF IS STRONGER AND SLOWER AND ACTUALLY HAS THE NRN SHORTWAVE BECOMING THE DOMINANT FEATURE WHILE BECOMING CLOSED OFF OVER LOWER MI LATE MON. THE ECMWF HAS THE MOST QPF AT 0.35-0.45 INCHES. WHILE NOT AT ALL SURE IF ANY OF THESE TWO SOLUTIONS WILL BE CORRECT...WILL USE THE 12/15 NAM AND 12/15 GEM SOLUTIONS WHICH ARE MORE IN THE MIDDLE OF THE ROAD. THE NAM IS CLOSER TO THE GFS WHILE THE GEM IS CLOSER TO THE ECMWF...BUT THEY ARE STILL MORE MODERATED SOLUTIONS TO THE TWO EXTREMES. THIS GIVES TOTAL QPF OF 0.25-0.35 INCHES...WHICH TRANSLATES TO ROUGHLY 3-5 INCHES OF SNOW...WHICH MATCHES UP TO THE PREVIOUS SHIFT AS WELL. ADDITIONAL...YET WEAKER...SHORTWAVES MAY MOVE THROUGH TUE INTO WED...WITH CONTINUED MODEL DISAGREEMENT. HOWEVER...MOISTURE LOOKS TO BE QUITE A BIT MORE LIMITED DURING THIS TIME FRAME SO WIDESPREAD PRECIP IS NOT AS MUCH OF AN ISSUE. MORE INTERESTINGLY...MODELS BRING AN 850MB THERMAL RIDGE ACROSS THE CWA LATE MON NIGHT THROUGH TUE...BRINGING 850MB TEMPS AS WARM AS 0C ACROSS THE CWA. WHILE THIS WILL ALLOW FOR MAX SFC TEMPS AROUND 30F...WET BULB ZERO TEMPS ABOVE THE SFC WILL BE BELOW ZERO. THIS IS WHERE PRECIP IS MORE OF AN ISSUE IN THAT THE DRY MID LEVELS WILL LEAVE THE DGZ DRY AND THE STRONG INVERSION BENEATH THE THERMAL RIDGE WILL TRAP PLENTY OF MOISTURE IN THE LOW LEVELS LATE MON NIGHT BEFORE THAT MOISTURE GETS MIXED BY DAYTIME HEATING TUE. COULD SEE SOME FREEZING DRIZZLE N OF LAKE MICHIGAN DUE TO SW WINDS OFF LAKE MICHIGAN AND UPSLOPE FLOW THERE. AN UPPER TROUGH THEN TUE NIGHT/WED MORNING...BRINGING A COOLER AIRMASS WITH IT. THE UPPER RIDGE THAT MODELS HAVE MOVING THROUGH LATE WED/WED NIGHT IS SLOWER THAN PREVIOUS MODEL RUNS...SO TEMPS MAY NOT GET AS WARM ON WED. WENT AHEAD AND LOWERED TEMPS A COUPLE OF DEGREES WED. THU THROUGH NEXT SUN IS EVEN MORE UNCERTAIN AS THE UPPER TROUGH MOVES INTO THE PLAINS. QUESTIONS ABOUT STRENGTH AND PLACEMENT OF THE TROUGH...ALONG WITH PHASING AND HOW MUCH/WHEN PIECES OF ENERGY CAN EJECT FROM THE TROUGH ARE IMPOSSIBLE TO ANSWER AT THIS POINT. THERE IS POTENTIAL FOR MUCH STRONGER SYSTEMS TO BE MOVING THROUGH THE REGION...WHICH INCLUDES POSSIBILITIES OF SIGNIFICANT PRECIP /EITHER MIXED PTYPE OR SNOW/. THIS PART OF THE FORECAST BEARS CLOSER MONITORING BY THOSE WITH TRAVEL/OUTDOOR INTERESTS AS FORECASTS ARE REFINED IN THE NEXT FEW DAYS. IT DOES LOOK LIKE ANOTHER ROUND OF COLDER AIR WILL MOVED INTO THE REGION LATE IN THE FORECAST PERIOD INTO EARLY NEXT WEEK. USED A CONSENSUS OF GUIDANCE AT THIS POINT GIVEN THE POOR MODEL TO MODEL AGREEMENT AND RUN TO RUN CONTINUITY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1247 PM EST SAT FEB 15 2014 SNOW AND IFR CONDITIONS AT CMX WILL ALSO SPREAD TO IWD AND SAW LATE THSI AFTERNOON AND EVENING AS A DISTURBANCE APPROACHES THE UPPER LAKES. EXPECT CONDITIONS TO BEGIN IMPROVING TO MVFR BY LATE EVENING AT KIWD AND KCMX AND OVERNIGHT TONIGHT AT KSAW. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 345 PM EST SAT FEB 15 2014 A SERIES OF WEAK TROUGHS MOVING THROUGH THE AREA WILL CONTINUE TO BRING ROUNDS OF LIGHT TO SOMETIMES MODERATE SNOW THROUGH WEDNESDAY. WINDS WILL GENERALLY STAY UNDER 20 KTS WITH TWO EXCEPTIONS. ONE WILL BE LATE THIS AFTERNOON AND TONIGHT AS E-NE WINDS WILL INCREASE TO 15 TO 25 KNOTS OVER THE WESTERN LAKE. THE SECOND WILL BE THE POTENTIAL FOR 20 TO 30 KT SE WINDS OVER MAINLY THE EAST HALF OF LAKE SUPERIOR ON MONDAY AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM. WITH THE LAKE ALMOST COMPLETELY ICE COVERED...NO SIGNIFICANT AREAS OF FREEZING SPRAY ARE EXPECTED. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR MIZ001- 003. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...TITUS AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS DULUTH MN
716 PM CST SUN FEB 16 2014 .UPDATE... ISSUED AT 710 PM CST SUN FEB 16 2014 GUSTY EAST WINDS TO 25 KT HAVE PRODUCED ENOUGH LIFT TO KICK OFF LOW CLOUDS AND FLURRIES ALONG THE NORTH SHORE AND WESTERN TIP OF LAKE SUPERIOR THIS EVENING. THIS EVENING SNOW WILL BE VERY LIGHT WITH NO ACCUMULATION. THE MAIN PERIOD OF ACCUMULATING SNOW WILL AROUND AROUND MIDNIGHT IN THE TWIN PORTS. HAVE INCREASED WINDS OVERNIGHT BASED ON LATEST NAM BUFR SOUNDINGS AND 23Z RUN OF HRRR SHOWING GUSTY SE WINDS AHEAD OF THE TROUGH. THE STRONGEST WINDS AND GUSTS TO 25 KT WILL BE FOUND ACROSS THE BRD LAKES REGION..EAST OVER THE ST CROIX RIVER VALLEY. DUE TO THE COMBO OF GUSTY WINDS AND FALLING SNOW...HAVE ALSO INTRODUCED AREAS OF BLOWING SNOW TO THE FCST. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 301 PM CST SUN FEB 16 2014 AT 300PM/2100Z...SURFACE HIGH PRESSURE WAS CENTERED OVER ONTARIO WITH ITS RIDGE AXIS STRETCHING SOUTH THROUGH THE NORTHLAND. THIS WAS PROVIDING THE NORTHLAND SUNNY TO MOSTLY SUNNY SKIES. HOWEVER...THERE WAS INCREASING CLOUD COVER WEST OF THE NORTHLAND AND ACROSS THE NORTHERN PLAINS AHEAD OF AN APPROACHING TROUGH/WARM FRONT STRETCHING FROM SOUTHERN ALBERTA AND THROUGH THE NORTHERN HIGH PLAINS IN EASTERN MONTANA AND WYOMING. THE EASTERN FORECAST AREA HAD VERY LIGHT TO CALM WIND...BUT THE WESTERN FORECAST AREA HAD INCREASING SE WINDS. THE TEMPERATURES RANGED FROM THE SINGLE DIGITS IN THE ARROWHEAD TO THE MID TO UPPER TEENS ACROSS THE REST OF THE FORECAST AREA. THE FOCUS FOR THIS FORECAST IS THE ROUND OF SNOW EXPECTED TO MOVE THROUGH THE NORTHLAND AFTER MIDNIGHT AND THROUGH MONDAY IN ADVANCE OF THE TROUGH/WARM FRONT WHICH WILL MOVE THROUGH THE NORTHLAND MONDAY. SOME MODELS INCREASED PCPN AMOUNTS FOR SOME AREAS...WHICH RESULTED IN INCREASING SNOWFALL AMOUNTS...SUCH AS FOR THE TWIN PORTS. WIDESPREAD SNOWFALL AMOUNTS AROUND 6 INCHES ARE EXPECTED FOR THE TWIN PORTS AREA AND ALONG THE INTERSTATE 35 CORRIDOR...AND CONSIDERING PERIODS OF HEAVY SNOWFALL RATES COULD MAKE FOR DIFFICULT DRIVING CONDITIONS FOR THE MORNING COMMUTE...I DECIDED TO EXPAND THE WINTER STORM WARNING TO THE SOUTH CENTRAL FORECAST AREA. SNOW WILL BEGIN TO SPREAD INTO NORTH CENTRAL AND CENTRAL MINNESOTA AROUND MIDNIGHT AS THE TROUGH/WARM FRONT MOVE INTO THE CENTRAL/EASTERN DAKOTAS AROUND THIS TIME. THE SNOW WILL QUICKLY SPREAD INTO NORTHEAST MINNESOTA AND NORTHWEST WISCONSIN AFTER MIDNIGHT AND MONDAY MORNING. THERE ARE STILL SOME DIFFERENCES IN MODEL PCPN AMOUNTS AND SLIGHTLY DIFFERENT TIMING. I LEANED ON A WIDE BLEND...BUT PERHAPS A LITTLE MORE TOWARDS THE SREF. THE MODELS...INCLUDING THE SREF...SUGGEST WIDESPREAD 4 TO 7 INCHES WITH THE HIGHEST AMOUNTS ACROSS THE CENTRAL AND EASTERN FORECAST AREA. DESPITE THE WARMER AIR WITH THIS SYSTEM...SEVERAL MODELS ARE SUGGESTING SNOW TO LIQUID RATIOS AROUND OR GREATER THAN 15 TO 1. THIS MAY IN PART DUE TO THE LIKELIHOOD OF SOME ENHANCED DEPTH AND LIFT IN THE DENDRITIC GROWTH ZONE...WHICH WILL HELP INCREASE THE SNOW TO LIQUID RATIOS. THE HIGHEST AMOUNTS OF SNOW WILL LIKELY BE ALONG THE NORTH SHORE...WHERE AMOUNTS COULD REACH UP TO 8 INCHES DUE TO A LITTLE LAKE ENHANCEMENT FROM SE TO E WINDS. GRANTED...THE LAKE IS FAIRLY ICE COVERED...BUT WE HAVE STILL BEEN SEEING SOME LAKE ENHANCEMENT AND LIGHT LAKE EFFECT SNOW RECENTLY. THE SNOW WILL BEGIN TO MOVE EAST OF THE NORTHLAND MONDAY AFTERNOON. HIGH TEMPERATURES WILL BE LIMITED TO THE LOW TO MID 20S ACROSS THE EASTERN FORECAST AREA...BUT PARTS OF THE WESTERN FORECAST WILL LIKELY SEE ABOVE FREEZING TEMPERATURES THANKS TO PARTIAL SUNSHINE IN THE MID TO LATE AFTERNOON. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 301 PM CST SUN FEB 16 2014 SIGNIFICANT SNOW SHOULD BE DIMINISHING RAPIDLY ACROSS THE EASTERN SECTIONS OF THE DULUTH CWA..OR ENDED ALTOGETHER..BY THE BEGINNING OF THE MONDAY NIGHT PERIOD. SECONDARY S/W TROF WILL ROTATE EASTWARD ACROSS THE NORTHLAND MONDAY NIGHT/TUE MORNING..WITH CONTINUED LOW LEVEL WARM ADVECTION IN OUR BRIEF EXCURSION INTO THE WARM SECTOR. THIS SHOULD BE SUFFICIENT TO SQUEEZE OUT SOME VERY LIGHT PRECIP. MOST LIKELY IN THE FORM OF SOME PATCHY LIGHT SNOW OVER THE FAR NORTH..BUT PROBABLY IN THE FORM OF FLURRIES OR SOME PATCHY LIGHT FREEZING DRIZZLE ALONG AND SOUTH OF THE HIGHWAY 2 CORRIDOR. OVERALL..NOT A MAJOR EVENT..BUT COULD BE ENOUGH TO PROLONG SLICK ROADS IN MANY AREAS IN THE WAKE OF MODERATE SNOWFALL TONIGHT AND MONDAY. WEAK COLD ADVECTION AND HIGH PRESSURE WILL THEN BUILD INTO THE REGION LATER TUESDAY/WEDNESDAY. HOWEVER..UNLIKE MOST OF THE LAST 2 MONTHS..THIS POST-FRONTAL AIRMASS WILL HAVE ITS SOURCE REGION IN THE DOWNSLOPE OF THE NORTHERN ROCKIES. AS A RESULT..TUE/WED SHOULD BE CONSIDERABLY WARMER ACROSS THE REGION..ESPECIALLY WITH THE STRONGER FEBRUARY SUN AND LONGER DAYS..WHICH WILL ALLOW INSOLATION TO INTERACT WITH THE LOWER ALBEDO OF THE FORESTED AREAS. WE HAVE RAISED MAX TEMPS SOME FROM THE PREVIOUS FORECAST FOR BOTH DAYS..AND SOME AREAS ON WED COULD PUSH 40 ACROSS NW WISCONSIN AND PARTS OF NE MN. NEXT RAPIDLY MOVING DISTURBANCE WILL MOVE ACROSS THE NORTHERN TIER OF STATES MID WEEK..AFFECTING THE NORTHLAND WED NIGHT/THUR. RIGHT NOW..MOST CURRENT MEDIUM RANGE GUIDANCE DEPICTS THE ORIENTATION AND DYNAMIC FORCING WITH THIS SYSTEM AS SIMILAR TO THE ONE FOR TONIGHT AND MONDAY..WITH A RAPID INCREASE IN STRONG UPWARD VERTICAL MOTION FIELDS DEVELOPING ACROSS MN LATER WED NIGHT/THUR MORNING. AIRMASS WILL NOT BE AS COLD..SO SNOW RATIOS WILL BE LOWER..AND SOME PRECIP COULD BE A MIX OR RAIN ACROSS THE FAR SOUTH DEPENDING ON THE EVENTUAL EVOLUTION OF THE WARM SECTOR. SO..SNOWFALL AMOUNTS MAY BE LESSER AND SNOW OF THE HEAVIER/WETTER VARIETY. HOWEVER..IT SHOULD BE NOTED THAT THE STRENGTH OF THE VERTICAL MOTION FIELDS AND RAPID DEVELOPMENT OF PRECIP WED NIGHT WOULD ARGUE FOR STRONG DYNAMIC AND DIABATIC COOLING OF THE LOWER PORTIONS OF THE ATMOSPHERE..AND THUS A MOSTLY SNOW SOLUTION. OF COURSE..THE ECM/GFS HAVE A HARDER TIME HANDLING THE NORTHWARD SURGE OF THE WARM AIR ALOFT..SO THE POTENTIAL FOR MIXED PRECIP OR RAIN SEEMS TO BE BACK ON THE TABLE A BIT MORE THAN THIS TIME YESTERDAY. PTYPE ISSUES SHOULD BECOME CLEARER WHEN THIS SYSTEM GETS INTO THE 84 HR FORECAST WINDOW OF THE WRF-BASED MODELS AND ENSEMBLE SYSTEMS THAT SEEM TO HANDLE THE RETURNING WARM LAYER IN STRONG WARM ADVECTION PATTERNS BETTER. FOR THE THUR-SAT TIME FRAME..MORE NORTHERLY COMPONENT TO THE FLOW ALOFT DEVELOPS ONCE AGAIN..WITH THE STORM TRACK RETREATING SOUTHWARD. AS A RESULT..PROGRESSIVELY COLDER AIR OF MORE ARCTIC ORIGIN SHOULD GRADUALLY BECOME ESTABLISHED ONCE AGAIN..ALONG WITH A FEW CHANCES FOR SOME LIGHT SNOW. ANOTHER STRONG PUSH OF VERY COLD ARCTIC AIR WITH 850 TEMPS AOB -25C LOOKS TO BE ON TAP FOR LATE NEXT WEEKEND AND THE BEGINNING OF THE WEEK OF FEB 24..JUST BEYOND THE RANGE OF THIS 7 DAY FORECAST WINDOW. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 615 PM CST SUN FEB 16 2014 GUSTY SOUTHEAST WINDS WILL PREVAIL OVERNIGHT AHEAD OF A STRONG FRONT. THE FRONT WILL SPREAD LOW CLOUDS AND MODERATE TO HEAVY SNOW ACROSS THE FORECAST AREA THROUGH THE NIGHT...MAINLY AFTER 06-08Z. THERE WILL BE A 4-6 HOUR WINDOW OF HEAVY SNOW WITH 1-2" PER HOUR SNOWFALL RATES THROUGH MONDAY MORNING. THE PERIOD OF GREATEST ACCUMULATION AND IFR/LIFR FLIGHT RESTRICTIONS ARE EXPECTED IN THE KINL-KBRD AREAS AROUND 08-12Z...SHIFTING EAST TO THE KHIB- KDLH AREAS DURING THE 10-15Z TIME FRAME...THEN MOVING OVER KHYR ROUGHLY BETWEEN 12-18Z. AS THE FRONT TRANSLATES EAST ACROSS THE REGION MONDAY AFTERNOON/EARLY EVENING...WINDS WILL TURN OUT OF THE WEST AND CONDITIONS WILL RAPIDLY IMPROVE. && .PRELIMINARY POINT TEMPS/POPS... DLH 5 25 18 37 / 100 100 10 20 INL 15 26 18 31 / 100 100 30 30 BRD 15 34 21 36 / 100 100 10 10 HYR 9 28 17 40 / 90 100 10 10 ASX 0 28 18 38 / 90 100 20 20 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WARNING FROM 2 AM TO 6 PM CST MONDAY FOR MNZ012-020- 021. WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST MONDAY FOR MNZ010-018-025-026-033>036. WINTER STORM WARNING FROM 2 AM TO 3 PM CST MONDAY FOR MNZ037-038. WINTER WEATHER ADVISORY FROM 2 AM TO 3 PM CST MONDAY FOR MNZ011- 019. WI...WINTER STORM WARNING FROM 2 AM TO 3 PM CST MONDAY FOR WIZ001>004- 006>009. LS...NONE. && $$ UPDATE...GRANING SHORT TERM...GROCHOCINSKI LONG TERM...MILLER AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1121 AM CST SAT FEB 15 2014 .UPDATE... ISSUED AT 1103 AM CST SAT FEB 15 2014 UPDATED TO INCLUDE 18Z AVIATION DISCUSSION BELOW. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 408 AM CST SAT FEB 15 2014 REGIONAL RADAR THIS MORNING HAS TWO AREAS OF ENHANCED REFLECTIVITY ASSOCIATED WITH A STRONG JET STREAK MOVING SE ACROSS THE NORTHERN PLAINS. ACROSS ND/SD...THE REFLECTIVITY PATTERN IS MORE DISORGANIZED AND IS WEAKER COMPARED TO ANOTHER AREA IN NEBRASKA WHICH HAS A BETTER ORIENTATION OF THE 92-70H FRONTOGENETIC REGIME. IN ADDITION...ACROSS THE UPPER MIDWEST...MOISTURE IS LACKING IN THE DENDRITIC GROWTH ZONE. ALTHOUGH THE LATEST 07Z RAP HAS INCREASED THE MOISTURE IN THIS GROWTH ZONE BY 12-15Z IN WESTERN MN...AM NOT TOTALLY CONVINCED BOTH THE MOISTURE AND LIFT WILL ORGANIZE ENOUGH TO WARRANT CATEGORICAL POPS NORTH OF THE MN RIVER VALLEY. AM LEANING TOWARD THE CONTINUED HIGHER POPS ALONG THE IA/MN BORDER BY 15-18Z...WITH LOWER CONFIDENCE FURTHER TO THE N/NE. WOULD LIKE TO SEE MORE -SN OBS IN SD/ND BEFORE CONFIDENCE INCREASES FOR SNOWFALL TOTALS GREATER THAN A LIGHT DUSTING NORTH OF THE MN RIVER VALLEY. HOWEVER...DUE TO THE STRENGTH OF THE FORCING BY 15-18Z ALONG THE IA/MN...THERE COULD BE A QUICK 1-2 INCHES OF SNOW BEFORE IT TAPERS OFF BY EARLY AFTN. ELSEWHERE...CONFIDENCE IS LOW FOR ANYTHING MORE THAN ONE HALF INCH. TEMPERATURES MAY REACH THE LOWER 30S ALONG THE LEE OF THE BUFFALO RIDGE TODAY AS UPSTREAM OBS IN SW ND/NW SD HAVE 30S ALREADY THIS MORNING. THE MEAN FLOW IN THE BOUNDARY LAYER WILL HELP ADVECT THESE TEMPS ACROSS SD...AND INTO SW MN LATER TODAY. ELSEWHERE...20S WILL BE COMMON. NO CHGS ON THE FORECAST TONIGHT AS CLEARING TAKES PLACE IN THE WAKE OF THIS SYSTEM. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 408 AM CST SAT FEB 15 2014 SEMI-ZONAL FLOW BECOMES ESTABLISHED BY 18Z SUNDAY...AND THE NEXT SYSTEM RACES TOWARD THE AREA. THE ATTENDANT PV REFLECTION IS A BIT DISJOINTED...WITH ONE POCKET PASSING ACROSS NORTHERN MN AND THE OTHER PASSING ACROSS IOWA. REGARDLESS...SHOULD SEE A DECENT PERIOD OF PRECIPITATION ON SUNDAY NIGHT AND MONDAY AS THE TROUGH TAKES ON A SLIGHT NEGATIVE TILT AND A HEALTHY BURST OF ISENTROPIC UPGLIDE ARRIVES /PER THE 280K-295K SURFACES/. THERMAL PROFILES ARE WARMER WITH THIS SYSTEM...AND 0-6KM SFC WET BULB TEMPS ILLUSTRATE THE POTENTIAL FOR LIGHT FREEZING DRIZZLE OR SLEET ACROSS SOUTHWEST/SOUTH CENTRAL MN ON SUNDAY NIGHT BETWEEN 03Z AND 12Z...WITH AREAS OF FREEZING DRIZZLE ACROSS THE SOUTHEAST ON MONDAY AFTERNOON AT THE END OF THE EVENT. SNOW ACCUMULATIONS DURING THE 24 HOUR PERIOD /00Z MON-00Z TUE/ COULD APPROACH WARNING CRITERIA /6 INCHES/ IN OUR NORTHERN WEST CENTRAL WI COUNTIES...TAPERING TO AROUND 3 INCHES IN THE TWIN CITIES...DOWN TO AROUND 1 INCH IN THE SOUTHWEST WHERE THE POTENTIAL FOR MIXED PRECIP EXISTS. TUESDAY THROUGH WEDNESDAY THEN LOOK TO BE BENIGN WEATHER-WISE IN THE WAKE OF THE SYSTEM...WITH THE MAIN HIGHLIGHT BEING WARMER TEMPERATURES WITH HIGHS IN THE MID 30S TO POSSIBLY EVEN LOWER 40S. ATTENTION AT THE END OF THE WORK WEEK WILL BE FOCUSED ON THE POTENTIAL FOR A NOTABLE SYSTEM BRINGING SIGNIFICANT SNOWFALL ACCUMULATIONS TO THE REGION. MODEL SOLUTIONS ARE ADMITTEDLY ALL OVER THE MAP WITH RESPECT TO THE SYNOPTIC DETAILS...BUT BOTH ECMWF AND GFS MODELS HAVE BEEN INSISTENT ON THE ARRIVAL OF AT LEAST ONE SUBSTANTIAL MID LATITUDE CYCLONE TOWARD NEXT WEEKEND. STAY TUNED... && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1103 AM CST SAT FEB 15 2014 QUICKLY MOVING SHORTWAVE AND SURFACE LOW CURRENTLY WORKING THROUGH THE REGION... HELPING TO GENERATE A BRIEF PERIOD OF MODERATE TO HEAVY SNOWFALL... PARTICULARLY OVER SOUTHERN LOCATIONS. CEILINGS AND VISIBILITIES WILL DIP INTO IFR RANGE FOR A 1-2 HOUR WINDOW AS THE ACTIVITY MOVES THROUGH... WITH SOME LOWER CEILINGS THEN LINGERING INTO THE EVENING. MAIN QUESTION/UNCERTAINTY IS WITH HOW LONG MVFR CEILINGS WILL LAST TONIGHT. UPSTREAM OBS SUGGEST IT SHOULD REMAIN FOR A WHILE... ALTHOUGH THE GUIDANCE WANTS TO DRY THINGS OUT IN THE BOUNDARY LAYER DURING THE NIGHTTIME HOURS... AND THE DRIER AIR ISN/T TOO FAR SOUTH OF THE MOISTURE STREAM ADVANCING FROM THE NORTHERN DAKOTAS. WE SHOULD EVENTUALLY SCOUR IT OUT... AND WILL THEN BE LOOKING AT ADVANCING AC AND CIRRUS AHEAD OF THE NEXT SYSTEM... WHICH WILL IMPACT THE REGION SUNDAY NIGHT. KMSP...PRIMARY CONCERNS ARE IN THE FIRST 1-2 HOURS OF THE FORECAST... WHEN SOME LIFR CONDITIONS ARE EXPECTED WITH A SHORT PERIOD OF HEAVY SNOW. THINGS WILL IMPROVE IN TERMS OF VISIBILITY AS QUICKLY AS THEY DETERIORATE. THE MAIN QUESTION THEN BECOMES HOW QUICKLY AND TO WHAT EXTENT CEILINGS WILL IMPROVE. FEEL THEY WILL GET ABOVE 017 FT FAIRLY QUICKLY... BUT SHOULD SEE MVFR LINGERING INTO TONIGHT FOR A DECENT AMOUNT OF TIME BEFORE SUFFICIENT SUBSIDENCE AND DRY AIR CAN SCOUR THINGS OUT. HOWEVER... THAT IS CERTAINLY SOMETHING TO WATCH AND THE IMPROVEMENT COULD COME EARLIER/LATER THAN EXPECTED. THINGS WILL THEN BE QUIET THROUGH SUNDAY UNTIL THE NEXT SYSTEM ARRIVES SUNDAY NIGHT. /OUTLOOK FOR KMSP/ SUNDAY NIGHT AND MONDAY...MVFR CEILINGS AND VISIBILITIES EXPECTED WITH SNOW... IFR CONDITIONS POSSIBLE. SOUTHEAST WIND 10 TO 20 KT SHIFTING WEST. MONDAY NIGHT...VFR. SOUTHWEST WIND 10 TO 20 KT. TUESDAY...VFR. SOUTHWEST WIND 10 TO 20 KT SHIFTING WEST. TUESDAY NIGHT...VFR. WEST WIND 5 TO 15 KT. WEDNESDAY...MVFR CEILINGS POSSIBLE WITH A CHANCE OF RAIN. SOUTH WIND 15 TO 25 KT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ UPDATE... SHORT TERM...JLT LONG TERM...LS AVIATION...
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
532 AM CST SAT FEB 15 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 408 AM CST SAT FEB 15 2014 REGIONAL RADAR THIS MORNING HAS TWO AREAS OF ENHANCED REFLECTIVITY ASSOCIATED WITH A STRONG JET STREAK MOVING SE ACROSS THE NORTHERN PLAINS. ACROSS ND/SD...THE REFLECTIVITY PATTERN IS MORE DISORGANIZED AND IS WEAKER COMPARED TO ANOTHER AREA IN NEBRASKA WHICH HAS A BETTER ORIENTATION OF THE 92-70H FRONTOGENETIC REGIME. IN ADDITION...ACROSS THE UPPER MIDWEST...MOISTURE IS LACKING IN THE DENDRITIC GROWTH ZONE. ALTHOUGH THE LATEST 07Z RAP HAS INCREASED THE MOISTURE IN THIS GROWTH ZONE BY 12-15Z IN WESTERN MN...AM NOT TOTALLY CONVINCED BOTH THE MOISTURE AND LIFT WILL ORGANIZE ENOUGH TO WARRANT CATEGORICAL POPS NORTH OF THE MN RIVER VALLEY. AM LEANING TOWARD THE CONTINUED HIGHER POPS ALONG THE IA/MN BORDER BY 15-18Z...WITH LOWER CONFIDENCE FURTHER TO THE N/NE. WOULD LIKE TO SEE MORE -SN OBS IN SD/ND BEFORE CONFIDENCE INCREASES FOR SNOWFALL TOTALS GREATER THAN A LIGHT DUSTING NORTH OF THE MN RIVER VALLEY. HOWEVER...DUE TO THE STRENGTH OF THE FORCING BY 15-18Z ALONG THE IA/MN...THERE COULD BE A QUICK 1-2 INCHES OF SNOW BEFORE IT TAPERS OFF BY EARLY AFTN. ELSEWHERE...CONFIDENCE IS LOW FOR ANYTHING MORE THAN ONE HALF INCH. TEMPERATURES MAY REACH THE LOWER 30S ALONG THE LEE OF THE BUFFALO RIDGE TODAY AS UPSTREAM OBS IN SW ND/NW SD HAVE 30S ALREADY THIS MORNING. THE MEAN FLOW IN THE BOUNDARY LAYER WILL HELP ADVECT THESE TEMPS ACROSS SD...AND INTO SW MN LATER TODAY. ELSEWHERE...20S WILL BE COMMON. NO CHGS ON THE FORECAST TONIGHT AS CLEARING TAKES PLACE IN THE WAKE OF THIS SYSTEM. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 408 AM CST SAT FEB 15 2014 SEMI-ZONAL FLOW BECOMES ESTABLISHED BY 18Z SUNDAY...AND THE NEXT SYSTEM RACES TOWARD THE AREA. THE ATTENDANT PV REFLECTION IS A BIT DISJOINTED...WITH ONE POCKET PASSING ACROSS NORTHERN MN AND THE OTHER PASSING ACROSS IOWA. REGARDLESS...SHOULD SEE A DECENT PERIOD OF PRECIPITATION ON SUNDAY NIGHT AND MONDAY AS THE TROUGH TAKES ON A SLIGHT NEGATIVE TILT AND A HEALTHY BURST OF ISENTROPIC UPGLIDE ARRIVES /PER THE 280K-295K SURFACES/. THERMAL PROFILES ARE WARMER WITH THIS SYSTEM...AND 0-6KM SFC WET BULB TEMPS ILLUSTRATE THE POTENTIAL FOR LIGHT FREEZING DRIZZLE OR SLEET ACROSS SOUTHWEST/SOUTH CENTRAL MN ON SUNDAY NIGHT BETWEEN 03Z AND 12Z...WITH AREAS OF FREEZING DRIZZLE ACROSS THE SOUTHEAST ON MONDAY AFTERNOON AT THE END OF THE EVENT. SNOW ACCUMULATIONS DURING THE 24 HOUR PERIOD /00Z MON-00Z TUE/ COULD APPROACH WARNING CRITERIA /6 INCHES/ IN OUR NORTHERN WEST CENTRAL WI COUNTIES...TAPERING TO AROUND 3 INCHES IN THE TWIN CITIES...DOWN TO AROUND 1 INCH IN THE SOUTHWEST WHERE THE POTENTIAL FOR MIXED PRECIP EXISTS. TUESDAY THROUGH WEDNESDAY THEN LOOK TO BE BENIGN WEATHER-WISE IN THE WAKE OF THE SYSTEM...WITH THE MAIN HIGHLIGHT BEING WARMER TEMPERATURES WITH HIGHS IN THE MID 30S TO POSSIBLY EVEN LOWER 40S. ATTENTION AT THE END OF THE WORK WEEK WILL BE FOCUSED ON THE POTENTIAL FOR A NOTABLE SYSTEM BRINGING SIGNIFICANT SNOWFALL ACCUMULATIONS TO THE REGION. MODEL SOLUTIONS ARE ADMITTEDLY ALL OVER THE MAP WITH RESPECT TO THE SYNOPTIC DETAILS...BUT BOTH ECMWF AND GFS MODELS HAVE BEEN INSISTENT ON THE ARRIVAL OF AT LEAST ONE SUBSTANTIAL MID LATITUDE CYCLONE TOWARD NEXT WEEKEND. STAY TUNED... && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 511 AM CST SAT FEB 15 2014 MAIN AVIATION CONCERN IS TIMING OF -SN ONCE IT DEVELOPS ACROSS WESTERN MN...AND SHIFTS EASTWARD ACROSS SOUTHERN MN DURING THE LATE MORNING/EARLY AFTN. AFT THE -SN ENDS...MVFR/IFR CIGS WILL BE POSSIBLE. REGIONAL RADAR HAD DEPICTED AN AREA OF -SN ACROSS SOUTHERN ND...STARTING TO MOVE TO THE E/SE ACROSS NE SD AS OF 515 AM. ALTHOUGH VFR CIGS REMAINED ACROSS ND UNDER THE HIGHER REFLECTIVITY...MODELS CONTINUED TO SATURATE THE ATMOSPHERE BY 15Z ACROSS SW/WC MN WHICH -SN SHOULD BEGIN. BASED ON TIMING OF OUR LOCAL MODEL...-SN SHOULD BEGIN NEAR KRWF BY 14Z...KAXN BY 15Z AND AT KSTC BY 17Z. THERE SHOULD BE A PERIOD OF IFR/MVFR VSBYS IN -SN. HOWEVER...IT DOESN/T LOOK TO BE HEAVY ENOUGH FOR VSBYS LESS THAN 1SM. BY 21Z...MOST OF THE -SN SHOULD BE EAST OF MPX TAF AREA...BUT MVFR CIGS SHOULD CONTINUE IN THE WAKE OF THE PRECIPITATION UNTIL AT LEAST 3-6Z. CONFIDENCE ON -SN DEVELOPING THIS MORNING IS HIGH...BUT LOW ON THE INTENSITY AND HOW LONG IT WILL LAST. WINDS WILL START FROM THE S/SSE ARND 8-12 KTS...BECOME LIGHT S/SW THIS AFTN...THEN NW OVERNIGHT. KMSP... SE WNDS WILL INCREASE ABV 6 KTS BY 14-15Z. VFR CIGS WILL DECREASE TO MVFR ONCE THE -SN STARTS ARND 1630-17Z...WITH A PERIOD OF IFR VBSYS IN -SN. THE MVFR CIGS /LOWER THAN 1.7K/ SHOULD REMAIN AT MSP AFT THE -SN ENDS...BUT SLOWLY LIFT DURING THE EVENING. VFR CONDS ARE POSSIBLE BY 12Z/16. CONFIDENCE ON -SN BY 18Z IS HIGH...BUT LOW CONFIDENCE ON VSBY/CIGS ONCE THE -SN DEVELOPS. WINDS WILL REMAIN FROM THE SE ARND 8-10 KTS THRU 23Z...THEN DECREASE AND BECOME MORE SW...THEN NW OVERNIGHT. EXPECT GUSTY WINDS DEVELOPING AFT 12Z/16. /OUTLOOK FOR KMSP/ SUN...VFR EARLY. MVFR/IFR IN -SN LATE. LIGHT...BECMG SE 10 KTS. MON...MVFR/IFR EARLY IN -SN. VFR BY AFTN. WIND WSW 5 KT. TUE...VFR. WIND SW TO W 5-10 KT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...JLT LONG TERM...LS AVIATION...JLT
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
408 AM CST SAT FEB 15 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 408 AM CST SAT FEB 15 2014 REGIONAL RADAR THIS MORNING HAS TWO AREAS OF ENHANCED REFLECTIVITY ASSOCIATED WITH A STRONG JET STREAK MOVING SE ACROSS THE NORTHERN PLAINS. ACROSS ND/SD...THE REFLECTIVITY PATTERN IS MORE DISORGANIZED AND IS WEAKER COMPARED TO ANOTHER AREA IN NEBRASKA WHICH HAS A BETTER ORIENTATION OF THE 92-70H FRONTOGENETIC REGIME. IN ADDITION...ACROSS THE UPPER MIDWEST...MOISTURE IS LACKING IN THE DENDRITIC GROWTH ZONE. ALTHOUGH THE LATEST 07Z RAP HAS INCREASED THE MOISTURE IN THIS GROWTH ZONE BY 12-15Z IN WESTERN MN...AM NOT TOTALLY CONVINCED BOTH THE MOISTURE AND LIFT WILL ORGANIZE ENOUGH TO WARRANT CATEGORICAL POPS NORTH OF THE MN RIVER VALLEY. AM LEANING TOWARD THE CONTINUED HIGHER POPS ALONG THE IA/MN BORDER BY 15-18Z...WITH LOWER CONFIDENCE FURTHER TO THE N/NE. WOULD LIKE TO SEE MORE -SN OBS IN SD/ND BEFORE CONFIDENCE INCREASES FOR SNOWFALL TOTALS GREATER THAN A LIGHT DUSTING NORTH OF THE MN RIVER VALLEY. HOWEVER...DUE TO THE STRENGTH OF THE FORCING BY 15-18Z ALONG THE IA/MN...THERE COULD BE A QUICK 1-2 INCHES OF SNOW BEFORE IT TAPERS OFF BY EARLY AFTN. ELSEWHERE...CONFIDENCE IS LOW FOR ANYTHING MORE THAN ONE HALF INCH. TEMPERATURES MAY REACH THE LOWER 30S ALONG THE LEE OF THE BUFFALO RIDGE TODAY AS UPSTREAM OBS IN SW ND/NW SD HAVE 30S ALREADY THIS MORNING. THE MEAN FLOW IN THE BOUNDARY LAYER WILL HELP ADVECT THESE TEMPS ACROSS SD...AND INTO SW MN LATER TODAY. ELSEWHERE...20S WILL BE COMMON. NO CHGS ON THE FORECAST TONIGHT AS CLEARING TAKES PLACE IN THE WAKE OF THIS SYSTEM. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 408 AM CST SAT FEB 15 2014 SEMI-ZONAL FLOW BECOMES ESTABLISHED BY 18Z SUNDAY...AND THE NEXT SYSTEM RACES TOWARD THE AREA. THE ATTENDANT PV REFLECTION IS A BIT DISJOINTED...WITH ONE POCKET PASSING ACROSS NORTHERN MN AND THE OTHER PASSING ACROSS IOWA. REGARDLESS...SHOULD SEE A DECENT PERIOD OF PRECIPITATION ON SUNDAY NIGHT AND MONDAY AS THE TROUGH TAKES ON A SLIGHT NEGATIVE TILT AND A HEALTHY BURST OF ISENTROPIC UPGLIDE ARRIVES /PER THE 280K-295K SURFACES/. THERMAL PROFILES ARE WARMER WITH THIS SYSTEM...AND 0-6KM SFC WET BULB TEMPS ILLUSTRATE THE POTENTIAL FOR LIGHT FREEZING DRIZZLE OR SLEET ACROSS SOUTHWEST/SOUTH CENTRAL MN ON SUNDAY NIGHT BETWEEN 03Z AND 12Z...WITH AREAS OF FREEZING DRIZZLE ACROSS THE SOUTHEAST ON MONDAY AFTERNOON AT THE END OF THE EVENT. SNOW ACCUMULATIONS DURING THE 24 HOUR PERIOD /00Z MON-00Z TUE/ COULD APPROACH WARNING CRITERIA /6 INCHES/ IN OUR NORTHERN WEST CENTRAL WI COUNTIES...TAPERING TO AROUND 3 INCHES IN THE TWIN CITIES...DOWN TO AROUND 1 INCH IN THE SOUTHWEST WHERE THE POTENTIAL FOR MIXED PRECIP EXISTS. TUESDAY THROUGH WEDNESDAY THEN LOOK TO BE BENIGN WEATHER-WISE IN THE WAKE OF THE SYSTEM...WITH THE MAIN HIGHLIGHT BEING WARMER TEMPERATURES WITH HIGHS IN THE MID 30S TO POSSIBLY EVEN LOWER 40S. ATTENTION AT THE END OF THE WORK WEEK WILL BE FOCUSED ON THE POTENTIAL FOR A NOTABLE SYSTEM BRINGING SIGNIFICANT SNOWFALL ACCUMULATIONS TO THE REGION. MODEL SOLUTIONS ARE ADMITTEDLY ALL OVER THE MAP WITH RESPECT TO THE SYNOPTIC DETAILS...BUT BOTH ECMWF AND GFS MODELS HAVE BEEN INSISTENT ON THE ARRIVAL OF AT LEAST ONE SUBSTANTIAL MID LATITUDE CYCLONE TOWARD NEXT WEEKEND. STAY TUNED... && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1146 PM CST FRI FEB 14 2014 VFR FOR THE NEXT 6-9 HOURS WITH CONDITIONS DETERIORATING QUICKLY INTO EARLY SATURDAY AFTERNOON. CLOUDS WILL INCREASE LATE TONIGHT...THICKENING AND LOWERING AHEAD OF A CLIPPER SYSTEM TRACKING ALONG A LINE FROM EASTERN SOUTH DAKOTA TO SOUTHWESTERN MINNESOTA AND NORTHEASTERN IOWA SATURDAY AFTERNOON. IFR VIS SNOW WILL LIKELY ACCOMPANY THE SYSTEM...PARTICULARLY ALONG THE MINNESOTA RIVER VALLEY. SNOWFALL AMOUNTS WILL RANGE FROM LESS THAN AN INCH AT AXN AND STC TO AROUND AN INCH AT RWF/MSP/RNH/EAU. KMSP...SKC TONIGHT...THEN CLOUDS INCREASE WITH SNOW BEGINNING LATE MORNING. INTENSITY WILL INCREASE QUICKLY WITH 1-2SM LIKELY FOR A FEW HOURS BEFORE TAPERING OFF IN THE MID TO LATE AFTERNOON. SNOW RATES SHOULD REMAIN 1/2 INCH PER HOUR OR LESS. /OUTLOOK FOR KMSP/ SUN...MVFR CIGS POSSIBLE WITH SN LIKELY LATE SUN NIGHT. LIGHT/VARIABLE WIND BECOMING SE 10-15 KTS. MON...MVFR CONDITIONS WITH -SN LIKELY EARLY. WIND SW 10 KT. TUE...VFR LIKELY. WIND SW 5-10 KT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...JLT LONG TERM...LS AVIATION...BORGHOFF
AREA FORECAST DISCUSSION
NWS SPRINGFIELD MO
935 PM CST Sun Feb 16 2014 .UPDATE... Issued at 934 PM CST SUN FEB 16 2014 We have made some tweaks to PoPs overnight along with adding a slight chance for thunder across much of the area. The latest surface analysis indicates a warm front extending from central Kansas, south to around Stillwater, Oklahoma. This front then continues southeast to around Lake Eufaula in east-central Oklahoma. Dew points to the south of this front across Oklahoma have actually risen into the lower and middle 50s. North of the front across the Ozarks, dew points ranged from the middle 20s to lower 30s. 9 PM temperatures were still in the middle to upper 40s across southwestern Missouri. In contrast, temperatures around Rolla and Salem were in the lower to middle 30s. Later this evening and overnight, weak surface low pressure will develop across north-central Oklahoma as digging short wave energy emerges across the central Plains. This low will pull northeast towards Kansas City by around sunrise. The warm front will follow suit and push northeast into western Missouri. Ahead of this front, lift will rapidly increase in both the low levels (isentropic upglide owing to a 50 knot low level jet) and the upper levels. Rain showers are therefore expected to blossom and increase in coverage starting around 06 UTC or shortly thereafter. We have maintained high-end likely and categorical PoPs across central Missouri where low-level moisture transport and theta-e advection will be maximized. In contrast, we have slightly lowered PoPs overnight near the Arkansas border where low level lift will be weaker. We have also added a slight chance for thunder generally along and north of the Interstate 44 corridor late tonight. The last three runs of the RAP and to some extent the NAM have latched onto a slug of MUCAPEs in the 300-600 J/kg range with source parcels rooted in the 825-750 mb layer. As that digging wave approaches, a quick cooling of mid-level temperatures may also support some small hail/graupel from any thunderstorms or heavier showers. We are still concerned about the potential for some freezing rain late tonight as those showers develop and push into the eastern Ozarks. While southeasterly winds will increase and result in steady or slowly rising temperatures, we will also see wet-bulbing as precipitation falls into a relatively dry low-level air mass. At this time, the main area of concern is up across eastern Maries and Phelps Counties where shower coverage will be greatest and temperatures will be right around the freezing mark. We will also have to watch areas down towards Salem and Eminence if shower activity manages to develop farther south. && .SHORT TERM...(This Evening through Monday) Issued at 146 PM CST SUN FEB 16 2014 Another challenging and complex day of temperatures across the area today. Clouds and easterly winds have wreaked havoc, with temperatures barely moving in central Missouri with modest warming elsewhere. In the coming hours, should see some additional warming with readings varying from the mid 30s in central Missouri to the low/mid 50s across southern Missouri. The forecast gets even more complicated tonight and Monday. A potent shortwave will traverse the upper Midwest sending a front through the area. Southerly flow will increase rapidly tonight ahead of this system. Should see temperatures fall to their minimums during the late evening hours, then steady off/rise during the overnight hours. This situation is rather similar to what we saw last Thursday night into Friday morning. In similar fashion there is a risk for some light freezing rain across the eastern Ozarks between 3-8 AM. Temperatures look to hold right near the freezing mark during this time frame, especially in the valleys and lower lying areas of Dent/Shannon/Oregon counties. This will not be a widespread risk, nor are we expecting more than just a thin glaze of patchy accumulation. Nevertheless, this could cause brief travel challenges for the morning rush. Main forcing with this system will be targeting areas to our north. Warm advection regime will spark isolated to widely scattered showers after midnight, and this will get more organized along a front that will quickly move through the area during the daylight hours of Monday morning. Rainfall amounts will be on the order of hundredths of an inch in most locations. Central Missouri could see totals in the one to two tenths of an inch range. As fast as rain moves in, it will exit to the east and we should see some clearing during the afternoon. Temperatures will continue to remain tricky, but stay seasonable for the time of year. Highs should range from the 40s east to mid 50s west. .LONG TERM...(Monday Night through Sunday) Issued at 146 PM CST SUN FEB 16 2014 Milder temperatures will begin to move in for Tuesday through the middle part of the week. Winds will become breezy especially over the western half of the area on Tuesday afternoon. Will have to watch for elevated fire weather conditions Tuesday afternoon depending on gusty winds and the lower atmosphere mixing out. The next storm system to affect the area will be moving in Wednesday night through Thursday. Cold front will move into the area very late Wednesday night into Thursday morning. Widespread rainfall is expected with embedded thunder. The better dynamics and thermal profiles for stronger convection will be just off to our southeast with an earlier passage of the cold front during the day through most of the Ozarks. Average rainfall amounts will range from a quarter to half an inch. Cooler weather will follow for the end of the week into next weekend. The models are in disagreement with the Friday night into Saturday time frame. The GFS keeps the area dry with a west- northwest flow and high pressure in control. The ECMWF has a robust shortwave moving through the area with quick round of precip and colder solution. At this time...have leaned more towards the ECMWF solution for the weekend time frame with precip chances Friday night into Saturday and colder temperatures. && .AVIATION...(For the 00Z TAFS through 00Z Monday Evening) Issued at 530 PM CST SUN FEB 16 2014 An upper level disturbance will move through the region from later tonight into early Monday morning. Ahead of this disturbance, a strong low level jet stream will develop and result in low level wind shear conditions. Surface winds will also increase and become gusty out of the southeast later tonight. Scattered rain showers are then expected to develop from later tonight into early Monday morning as low level moisture increases. That increase in moisture is also expected to lead to the development of MVFR ceilings. There is one weather model that indicates that enough instability will be present for a few thunderstorms. Given that this is the only model indicating this potential, we have not included a mention of thunder at this time. A cold front will then pass through southern Missouri around mid-morning on Monday. This front will sweep precipitation out of the area with MVFR ceilings lagging for an hour or two. Winds behind this front will shift to the west and then northwest and remain gusty. Skies will clear by early afternoon with winds beginning to diminish around sunset. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ UPDATE...Schaumann SHORT TERM...Gagan LONG TERM...Griffin AVIATION...Schaumann
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1030 PM MST Fri Feb 14 2014 .DISCUSSION... Update forthcoming as a few changes have been made. Winds along the Rocky Mountain Front have decreased. Gusts to 40 or 45 mph are still possible for the next few hours but RUC analysis continues to indicate 700 mb winds will decrease overnight. Therefore, have canceled the High Wind warning. Radar returns indicate snow continuing to fall over the Rocky Mountain Front and, to a lesser extent, the mountains of southwest Montana so will allow the winter weather highlights to ride. Have lowered pops across most of the Hi-Line for the remainder of the evening. Temperatures look good. && .AVIATION... UPDATED 0530Z. Several weather disturbances pushing through Montana during the period. Winds decreasing overnight along the Northern Rockies and north central Montana. Areas of snow showers are possible over the mountains of southwest Montana early in the period with a chance for MFR conditions near the snow showers. Conditions will improve Saturday morning and early afternoon with increasing cloudiness after 00z and and areas of showers as the next disturbance moves in from the west. && .PREV DISCUSSION...ISSUED 244 PM MST Fri Feb 14 2014 Tonight through Sunday...Windy conditions will continue through this evening over portions of North Central MT as an upper level disturbance continues to move through the region. Additionally...the westerly flow is allowing for snow to fall over the Rocky Mountain Front and portions of Southwest MT. The best snow accumulations will fall in the mountains...but a few mountain pass roadways could be impacted through the evening hours...thus the advisory will continue. The next change was to add a high wind watch for all of North Central MT for late Saturday night through Sunday night. Both the NAM/GFS continue to prog a fairly strong wind event over much of the region...thus the watch has been issued. There will continue to be a small chance for precip at lower elevations over the weekend and a good chance for precip in the mountains. At this time I held off on mentioning the potential for freezing rain on Sunday as the westerly flow should keep the precip either just rain or snow...however this will be watched closely. Temperatures will continue to run a few degrees above normal for most areas through the weekend. Brusda Sunday night through Friday...A generally moist and unsettled pattern will persist over the region through most of the forecast period. Westerly flow brings dry conditions to the plains and precipitation to the Continental Divide into Tuesday. A low pressure system with ample Pacific moisture and associated cold front move across Montana Tuesday night into Wednesday bringing accumulating mountain snowfall to elevations above 5000 feet, with rain/snow mix possible at lower elevations. Models remain in agreement that a very unsettled period will linger Tuesday through Thursday as multiple disturbance bring precipitation to various parts of Central Montana. Timing and location of precipitation during this period is somewhat poorly agreed upon; standard for a pattern of this nature. In the wake of a secondary front passing Thursday, cold air will move in from the north. Temperatures will drop noticeably but do not look to go much below zero at this time. Overall temperatures will remain warm into Wednesday before beginning a downward trend into the weekend. With a moist and unstable pattern expected, POP was raised quite a bit over the mountains, with valleys to a lesser extent, during almost the entire long term forecast. && .PRELIMINARY POINT TEMPS/POPS... GTF 30 46 35 45 / 20 10 20 20 CTB 27 43 30 41 / 20 10 30 20 HLN 28 47 32 46 / 30 20 30 30 BZN 22 45 30 45 / 40 20 30 40 WEY 20 37 25 36 / 100 60 90 80 DLN 25 46 31 42 / 50 30 40 50 HVR 27 41 29 45 / 20 0 30 20 LWT 28 42 32 42 / 20 0 30 20 && .TFX WATCHES/WARNINGS/ADVISORIES... HIGH WIND WATCH from late Saturday night through late Sunday night Blaine...Cascade...Chouteau...Eastern Glacier...Eastern Pondera...Eastern Teton...Fergus...Hill...Judith Basin... Liberty...Northern Rocky Mountain Front...Southern Rocky Mountain Front...Toole. WINTER WEATHER ADVISORY until 5 AM MST Saturday Beaverhead... Gallatin...Madison. WINTER WEATHER ADVISORY until 5 AM MST Saturday Northern Rocky Mountain Front...Southern Rocky Mountain Front. && $$ weather.gov/greatfalls www.twitter.com/NWSGreatFalls www.facebook.com/US.NationalWeatherService.GreatFalls.gov
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1212 AM EST FRI FEB 14 2014 .SYNOPSIS...AN UPPER LEVEL DISTURBANCE AND ATTENDANT SURFACE LOW PRESSURE SYSTEM WILL CROSS THE REGION THIS MORNING. HIGH PRESSURE WILL BUILD IN BEHIND THE SYSTEM ON SUNDAY. && .NEAR TERM /THROUGH SATURDAY/... AS OF 840 PM FRIDAY... THE LATEST SURFACE ANALYSIS SHOWED A SURFACE LOW OVER KENTUCKY MOVING EAST...WITH COOLING CLOUD TOPS MOVING OVER THE APPALACHIANS ALTHOUGH THE HIGHER RADAR REFLECTIVITY WAS FARTHER WEST...BASICALLY IN THE AXIS OF HIGHER PRECIPITABLE WATER VALUES ON THE LATEST SPC MESOANALYSIS PAGE THAT EXTENDED ACROSS EASTERN KENTUCKY AND TENNESSEE INTO ALABAMA AND NORTHWEST GEORGIA. THE LATEST KGSO SOUNDING AT 00Z WAS VERY DRY...ALTHOUGH SURFACE DEW POINTS EVEN IN THE NORTHWEST PIEDMONT...IN THE TEENS IN SOME PLACES VERY EARLY THIS EVENING...HAD RISEN INTO THE UPPER 20S SUCH THAT DEW POINTS IN CENTRAL NORTH CAROLINA RANGED FROM THE UPPER 20S TO THE MID 30S. IN A FEW LOCATIONS...ESPECIALLY OVER PARTS OF THE SANDHILLS AND THE COASTAL PLAIN WHERE CLOUDS WERE SLOWER MOVING IN...TEMPERATURES FELL QUICKLY INTO THE UPPER 30S BUT THESE VALUES SHOULD STABILIZE GIVEN THE DECENT SURFACE MOISTURE AND THE CLOUDS MOVING IN. GOOD LIFT IS FORECAST BY THE GUIDANCE LATE TONIGHT WITH 850MB THETA- E VALUES INCREASING AS THE STRONG MID-LEVEL TROUGH APPROACHES FROM THE WEST. GOOD DIVERGENCE IS NOTED ON WATER VAPOR IMAGERY AND GOOD DIVERGENCE IS ALSO FORECAST OVERNIGHT BY THE RAP. THE PRECIPITABLE WATER AXIS IS FORECAST BY THE RAP TO MOVE INTO CENTRAL NORTH CAROLINA BY 09Z...COINCIDENT WITH THE LATEST HRRR WHICH SHOWS THE LEADING EDGE OF PRECIPITATION DEVELOPING A LITTLE FASTER OVER THE SANDHILLS AND THE PIEDMONT BETWEEN 08Z AND 10Z NEAR WHERE THE RAP FORECAST ABOUT 100J/KG OF MUCAPE IN THE LAYER BETWEEN 1000MB AND 700MB. THIS PRECIPITATION COULD SPREAD NORTHEAST TOWARD KRWI AND KIXA PRIOR TO SUNRISE...SO HAVE SPED UP THE TIMING OF THE CHANCES FOR PRECIPITATION AFTER MIDNIGHT. FOR THE OVERNIGHT HOURS...THE WET- BULB ZERO TEMPERATURES RISE TO FREEZING OR ABOVE IN CENTRAL NORTH CAROLINA BY 04Z...AND PARTIAL THICKNESSES ARE INDETERMINATE. SO... REVIEWING THE BUFR AND RAP SOUNDINGS FOR THE ABOVE-FREEZING LAYER DEPTH...THROUGH 12Z ALL OF THAT GUIDANCE IS SUFFICIENTLY DEEP WITH THAT LAYER...AT LEAST TO NEAR 2000FT...TO KEEP THE TYPE LIQUID. MADE SOME ADJUSTMENTS TO LOWS BASED UPON CURRENT TRENDS...A LITTLE COOLER WHERE THE TEMPERATURES HAD FALLEN FASTER...AND A DEGREE OR TWO RISE IN THE TRIAD DUE TO THE QUICKER ONSET OF CLOUDS. WILL CONTINUE THE POTENTIAL FOR PATCHY FOG IN THE FORECAST BUT DELAYED THE TIMING TO ONLY BE COINCIDENT WITH ANY CHANCES FOR RAIN. SATURDAY...THE CLIPPER SURFACE WAVE WILL DEEPEN AS IT MOVES QUICKLY ENE THROUGH CENTRAL AND EASTERN NC...BEFORE BOMBING AS IT TURNS NE UP THE MIDDLE ATLANTIC COAST...BENEATH THE STRONGLY DYNAMIC AND INCREASINGLY NEGATIVELY-TILTED TROUGH ALOFT. IN A SIMILAR SYNOPTIC PATTERN AND RADAR PRESENTATION AS THE MID-UPPER LOW ON THU...THOUGH ON A SLIGHTLY MORE SOUTHERN TRACK...A DEFORMATION BAND WILL DEVELOP ON THE WEST SIDE OF THE RAPIDLY DEEPENING LOW...AND SUBSEQUENTLY PIVOT EASTWARD THROUGH CENTRAL NC THROUGH MID AFTERNOON. BASED ON THE HIGH BIAS DISPLAYED WITH PRECIPITATION AMOUNTS BY THE NWP GUIDANCE FOR THE EVENT FROM THU...WILL FOLLOW THE MORE SUBDUED CONSENSUS OF THE 12Z ECMWF/NAM OF AROUND ONE QUARTER INCH STORM TOTAL RAIN. P-TYPE SHOULD INDEED BE JUST THAT - RAIN - OWING TO A MILD AND RELATIVELY DEEP BOUNDARY LAYER THAT SHOULD COMPLETELY MELT SNOWFLAKES GENERATED IN...AND FALLING FROM...A COLD/BELOW FREEZING AND STEEP LAPSE RATE-BEARING LAYER ALOFT. THERE IS STILL A NON-ZERO CHANCE OF SOME WET SNOWFLAKES ON THE VERY BACK SIDE OF THE PRECIPITATION OVER THE NORTHERN PIEDMONT...MAINLY TOWARD THE TRIAD AND KTDF...AROUND 15Z AS THE NAM BUFR AND RAP SOUNDINGS DIMINISH THE ABOVE FREEZING LAYER BELOW 1000FT. THIS MAY BE OVERDONE...THOUGH... GIVEN EXPECTED SURFACE TEMPERATURES...AND BY THEN IT IS ANTICIPATED THE HIGHER-RATE PRECIPITATION WILL BE SHIFTING OFF TO THE EAST. NEVERTHELESS...IF THE PACE OF PRECIPITATION IS SLOWER TO SHIFT EAST THAN ANTICIPATED...THIS MAY HAVE TO BE REINTRODUCED TO THE FORECAST BUT IMPACT...IF IT OCCURS...SHOULD BE QUITE SMALL OWING TO THE SURFACE TEMPERATURES. THE BIGGER STORY WILL BE VERY STRONG NW WINDS THAT WILL DEVELOP IN THE TIGHT PRESSURE GRADIENT BEHIND THE DEPARTING LOW AND INCOMING UPSTREAM HIGH PRESSURE. BUFR SOUNDINGS INDICATE MIXED LAYER WINDS OF 25-30 KTS...WITH WINDS AT THE TOP OF THE MIXED IN THE MID-UPPER 30S KTS. THIS MIXING SHOULD SUPPORT SUSTAINED WINDS BETWEEN 15-25 KTS...WITH FREQUENT GUSTS OF 25-30 KTS...DEVELOPING AS THE CLEARING SPREADS EAST AND THE MIXED LAYER DEEPENS. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... AS OF 300 PM FRIDAY... AS LOW PRESSURE EXITS TO THE NORTHEAST SKIES WILL CLEAR OUT FOR MOST OF SATURDAY NIGHT BEFORE CLOUDS BEGIN TO MOVE IN AGAIN EARLY SUNDAY MORNING AS A MUCH DRIER...WEAKER CLIPPER SYSTEM APPROACHES FROM THE NORTHWEST. IN ADDITIONS THE SURFACE FLOW WILL BECOME VERY WEEK AND RADIATIONAL COOLING WILL ENSUE FOR MOST OF THE NIGHT...HELPING TEMPERATURES DROP INTO THE MID TO UPPER 20S FOR LOWS SATURDAY NIGHT. ON SUNDAY THE DRY CLIPPER SYSTEM DROPS THROUGH THE WEAKENING UPPER LEVEL TROUGH. MOST OF THE LIMITED MOISTURE WITH THIS SYSTEM IS LEFT ON THE WEST SIDE OF THE APPALACHIANS AND THE SYSTEM DRIES OUT PRETTY QUICKLY. WILL LEAVE THE FORECAST DRY WITH SOME CLOUDINESS...ESPECIALLY IN THE NORTH...THAT WILL HELP TO KEEP MAX TEMPS DOWN ON SUNDAY. EXPECT MID 40S NW TO LOWER 50S ACROSS THE SOUTH WHERE CLOUD COVER WILL BE LIMITED. SURFACE HIGH PRESSURE WILL BUILD TO THE NORTHWEST...KEEPING NORTHERLY FLOW OVER CENTRAL NC THROUGH SUNDAY NIGHT. THIS WEAK COLD AIR ADVECTION AND MOSTLY CLEAR SKIES WILL ONCE AGAIN BRING LOWS SUNDAY NIGHT DOWN INTO THE MID 20S TO LOW 30S. ON MONDAY THE HIGH SHIFTS EASTWARD ACROSS THE MID ATLANTIC STATES AND WILL TRY TO SET UP A BRIEF HYBRID/IN SITU CAD EVENT...DEPENDING ON WHAT MODEL YOU BELIEVE. WHILE THE WEDGE FRONT WONT REALLY HAVE A CHANCE TO GET LOCKED IN...IT WILL BE ENOUGH TO MAKE SKIES OVERCAST BY MONDAY AFTERNOON WITH SOME DRIZZLE POSSIBLE...MAINLY ACROSS THE NW PIEDMONT. HIGHS UPPER 40S NW TO MID 50S SE. BY MONDAY NIGHT THE HIGH MOVES OFFSHORE AND WE BEGIN TO ENTER A WARM AIR ADVECTION REGIME BETWEEN THE HIGH OFFSHORE AND AN APPROACHING FRONTAL SYSTEM WEST OF THE MOUNTAINS. LOWS WILL MODERATE TO THE MID 30S TO UPPER 40S MONDAY NIGHT. WE WILL STAY DRY BUT MOISTURE WILL STEADILY INCREASE INTO TUESDAY. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 300 PM FRIDAY... CONFIDENCE DECREASES IN THE FORECAST BY TUESDAY AS A FRONTAL SYSTEM APPROACHES FROM THE WEST. WHILE THERE IS HIGH CONFIDENCE THAT A FRONT WILL CROSS CENTRAL NC SOMETIME ON TUESDAY...DETAILS REGARDING THE POSITION AND STRENGTH OF THE PARENT LOW AND AMOUNT OF QPF ARE ALL MURKY AT THIS TIME. WE DO KNOW HOWEVER THAT WITH TEMPERATURES EXPECTED TO BE IN THE 60S THAT THIS WILL BE AN ALL LIQUID EVENT. MODEL SOUNDINGS SHOWN IN BUFKIT LEAD TO FAIRLY HIGH CONFIDENCE THAT THERE WONT BE ANY INSTABILITY AVAILABLE ON TUESDAY FOR THUNDER. THE FRONT WILL STALL OUT SOMEWHERE SOUTH OF THE AREA ON TUESDAY NIGHT WITH LOWS GENERALLY IN THE LOW TO MID 40S. ON WEDNESDAY MORNING THE FRONT WILL RETREAT BACK TO THE NORTH AS A WARM FRONT AND CROSS THE AREA ONCE AGAIN...WITH PRECIPIATION POSSIBLE INTO WEDNESDAY AFTERNOON. SOUNDINGS INDICATE THEIR MAY BE WEAK SURFACE BASED CAPE OF LESS THAN 500 J/KG AVAILABLE OF THE VERY TALL AND SKINNY VARIETY WITH A DECENT CAP AT 850MB THAT IT WOULD HAVE TO BUST THROUGH...MAKING CONFIDENCE FOR THUNDER SLIGHTLY BETTER FOR WEDNESDAY BUT STILL NOT LIKELY. WITH SW FLOW RETURNING HIGHS WILL SOAR INTO THE MID 60S TO EVEN LOWER 70S POSSIBLE ACROSS THE SOUTH. WEDNESDAY NIGHT SHOULD BE DRY WITH LOWS MODERATING TO THE UPPER 40S TO LOW 50S. FAIRLY STRONG LOW PRESSURE IS EXPECTED TO MOVE OUT OF THE MIDWEST UP THROUGH THE GREAT LAKES REGION ON THURSDAY. CENTRAL NC WILL REMAIN NICELY IN THE WARM SECTOR AHEAD OF THIS SYSTEM ON THURSDAY AND THE ANCHORED BERMUDA HIGH WILL KEEP MOIST SOUTHERLY FLOW OVER THE AREA. HIGHEST TEMPERATURES OF THE SEASON MAY BE IN ORDER AS HIGHS GO INTO THE UPPER 60S TO MID 70S NW TO SE. WITH THE EXTRA MOISTURE EXPECT PARTLY TO MOSTLY CLOUDY SKIES. ON FRIDAY THE FRONTAL SYSTEM BECOMES MORE EAST TO WEST ORIENTED AS THE PARENT LOW SPEEDS OFF TO THE NORTHEAST. EXPECT PRECIPITATION TO OVERSPREAD THE ENTIRE AREA BY FRIDAY AFTERNOON. WITH A LOT OF MOISTURE AVAILABLE THIS COULD SHAPE UP TO BE A FAIRLY HEAVY RAIN EVENT BUT IT IS TOO EARLY TO TELL AT THIS TIME. HIGHS FRIDAY DEPENDENT ON FRONTAL LOCATION. && .AVIATION /06Z SATURDAY THROUGH TUESDAY/... AS OF 1210 AM SATURDAY... AN AREA OF LOW PRESSURE TRACKING THROUGH THE CAROLINAS TONIGHT THROUGH MIDDAY WILL BRING A 3 TO 6 HOUR PERIOD OF SUB-VFR CEILINGS AND RAIN TO ALL THE TERMINALS. VFR CONDITIONS ARE EXPECTED TO RAPIDLY RETURN BETWEEN 15Z WEST AND 18Z-21Z EAST AS THE SYSTEM DEPARTS SATURDAY. WINDS WILL SHIFT FROM SW TO NW AND BECOME VERY STRONG AND GUSTY ONCE THE RAIN DEPARTS...WITH SUSTAINED WINDS OF 15 TO 20KT...GUSTING TO 25-35KT. WINDS WILL SUBSIDE AFTER DARK WITH A FEW SPRINKLES POSSIBLE OVERNIGHT AS AN UPPER LEVEL DISTURBANCES MOVES INTO THE AREA. OTHERWISE...DRY VFR CONDITIONS ARE EXPECTED THROUGH EARLY NEXT WEEK. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DJF NEAR TERM...MWS/DJF SHORT TERM...ELLIS LONG TERM...ELLIS AVIATION...CBL
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
944 PM CST SUN FEB 16 2014 .UPDATE... ISSUED AT 944 PM CST SUN FEB 16 2014 INCOMING MODEL GUIDANCE AND OBSERVATIONS AGREE WITH THE PREVIOUS UPDATE. THE POTENTIAL FOR MORE SIGNIFICANT SNOWFALL (AROUND 6 INCHES) CONTINUES TO DECREASE. MOST AREAS WILL RECEIVE 1 TO 4 INCHES...WITH THE HIGHER AMOUNTS NEAR THE INTERNATIONAL BORDER AND EAST OF THE VALLEY. IT WOULD APPEAR THAT THE TIMING OF INDIVIDUAL FEATURES (UPPER SHORTWAVES...JET STREAKS...FRONTOGENESIS) IS JUST A BIT OFF TO PRODUCE ANY ORGANIZED BANDS OF SNOWFALL. UPDATE ISSUED AT 712 PM CST SUN FEB 16 2014 RADAR IMAGERY INDICATES MODERATE TO HEAVY SNOWFALL ACROSS NORTHCENTRAL NORTH DAKOTA. THE 23Z RAP AND 21Z MPX HOPWRF APPEAR TO HAVE THE BEST HANDLE ON THE CURRENT SITUATION. THE UPPER TROUGH HAS YET TO ENTER THE WESTERN DAKOTAS...AND THIS SLOWER TRANSITION EASTWARD IS LIKELY AFFECTING THE OVERALL PROGRESSION OF THE SYSTEM. THERE IS A LEAD UPPER WAVE RESPONSIBLE FOR THE SNOW ACROSS NC ND...AND THE MAIN UPPER WAVE WILL NOT BE ABLE TO MERGE WITH THE LEAD WAVE. WITH ALL OF THIS SAID...THE RAP DEPICTS MULTIPLE UPPER JET STREAKS MOVING THROUGH THE REGION TONIGHT. PWATS WILL BE 0.4 TO 0.5 INCHES...SO PERIODS OF MODERATE TO HEAVY SNOWFALL STILL LIKELY. FOLLOWING THE 23Z RAP/21 MPX HOPWRF...THE MOST LIKELY WIDESPREAD SNOWFALL WILL BE ACROSS THE DVL BASIN AND NORTHERN VALLEY THROUGH 06Z. AS THE MAIN UPPER TROUGH APPROACHES...EXPECT MORE WIDESPREAD SNOWFALL TO DEVELOP ALONG AND EAST OF THE VALLEY AFTER 06Z. THESE MODELS INDICATE 2-4 INCHES DVL BASIN INTO THE NORTHERN VALLEY THROUGH MIDNIGHT...AND THEN 2-4 INCHES EAST OF THE VALLEY AFTER MIDNIGHT (WITH 1-3 INCHES ELSEWHERE). THIS BASICALLY AGREES WITH THE PREVIOUS FORECAST...BUT JUST A BIT HIGHER ACROSS THE DVL BASIN. SOUTHERLY WINDS CONTINUE TO INCREASE...AND BLOWING SNOW WILL ALSO BE AN ISSUE. && .SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT) ISSUED AT 319 PM CST SUN FEB 16 2014 SNOW AMOUNTS AND TIMING REMAINS THE ISSUE. 12Z MODELS AND SHORT RANGE MODELS BACKED OFF ON TIMING OF MAIN SNOW BAND NOT ARRIVING INTO THE RED RIVER VALLEY TIL 03-06Z AND EASTERN FCST AREA AFTER 06Z. HRRR/RAP/18Z NAM CATCHES ONTO SNOW BANDS IN EASTERN MONTANA DEVELOPING NORTH OF SURFACE LOW IN SOUTHEASTERN MONTANA AND NEAR SHORT WAVE MOVING THRU MONTANA. AHEAD OF THIS MAIN PRECIPITATION BAND IS INITIAL WARM ADVECTION BAND THAT HAS BEEN MOVING EAST SLOWLY THRU WESTERN MANITOBA INTO ERN ND. SNOW WITH THIS BAND LOOKS GOOD ON RADAR BUT OBS INDICATE SNOWFALL PATCHY. UNSURE EXACTLY HOW IT WILL EVOLVE...BUT MAIN UPPER TROUGH IS STILL OVER WRN/CNTRL MONTANA AND ALL MODELS SHOW GOOD UPPER LEVEL DIVERGENCE AHEAD OF IT AND DECENT 700 MB VERTICAL MOTION ALONG WITH GOOD ISENTROPIC LIFT ALONG THE 290K SURFACE AHEAD OF SYSTEM SPREADING INTO ERN ND/NW MN TONIGHT. SO DESPITE A BIT LATER START STILL LOOKING FOR SAME IDEA IN TERMS OF SNOW TOTALS WITH 1-2 FAR WEST TO 3 OR SO IN THE RED RIVER VALLEY TO 4-5 EASTERN FCST AREA. SNOW WILL END IN THE RRV BY 12Z AND IN THE EAST BY 15Z. SOUTH- SOUTHEAST WINDS GUSTY TO 30 KTS AT TIMES THIS AFTN WITH NAM BUFKIT SOUNDINGS INDICATING PEAK MIXING IN LOWEST LAYERS 00Z-03Z IN THE RED RIVER VALLEY WHERE 28-30 KTS AVAILABLE. PUBLIC REPORTS INDICATE LOW LEVEL BLOWING SNOW/DRIFTING AND IN SPOTS POOR VISIBILITY. WILL MAINTAIN THIS IDEA INTO THE EVENING. WHERE SNOW DOES OCCUR WITH WIND NEAR BLIZZARD CONDITIONS WILL OCCUR BUT WINDS APPEAR TO BE BLO BLIZZARD THRESHOLD UNLESS SOMETHING CHANGES. THUS WINTER WX ADVISORY LOOKS GOOD...EVEN FOR WESTERN FCST AREA WHERE SNOW TOTALS ARE BLO ADV THRESHOLDS FOR SNOWFALL. CLEARING WILL MOVE IN MONDAY BEHIND THE FRONT WITH A WEST WIND AND WARMER AIRMASS WITH HIGHS 30-35 IN MOST AREAS MON AFTN. MONDAY NIGHT WILL BE MILD AS WELL WITH TEMPS HOLDING UP WITH WEST BREEZE AND SOME MID LEVEL CLOUDS MOVING BACK IN AS A SHORT WAVE MOVES EAST INTO NORTH DAKOTA. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 319 PM CST SUN FEB 16 2014 AFOREMENTIONED SHORT WAVE WILL MOVE INTO MINNESOTA TUESDAY AND MAY PRODUCE A LITTLE LIGHT SNOW IN THE LAKE OF THE WOODS REGION SO KEPT LOW POPS. OTHERWISE PRETTY MILD AGAIN AS SFC FLOW REMAINS WEST OR SOUTHWEST. HIGH PRESSURE DROPS IN TUES NIGHT...THEN SOUTHEASTERLY FLOW WILL PICK UP WED AFTN AHEAD OF NEXT LOW TO MOVE THROUGH SOUTHERN CANADA. WILL RESTRICT SOME POPS FOR LIGHT SNOW AHEAD OF THIS SYSTEM TO THE AFTN IN NE ND. OR WEDNESDAY NIGHT THROUGH SUNDAY.. LOW AMPLITUDE PROGRESSIVE FLOW BEGINS TO AMPLIFY THIS PERIOD. UPPER RIDGE FORECAST TO REBUILD ALONG 140W WITH TROUGH NEAR 90W. BY THE END OF THE PERIOD THE PATTERN SHIFTS EAST ABOUT 10 DEGREES PUTTING THE NORTHERN PLAINS BACK INTO A COLDER PATTERN. FOR WEDNESDAY EVENING INTO THURSDAY A STRONG LOW TRACKS SLOWLY JUST NORTH OF THE INTERNATIONAL BORDER. LIGHT SNOWS FORECAST AHEAD OF THE FRONT ON THURSDAY IN UPGLIDE ZONE...SIMILAR TO SYSTEM GOING THROUGH REGION TODAY AND TONIGHT. MODELS IN FAIR AGREEMENT THAT WRAP AROUND SNOWS WILL MOVE ACROSS MAINLY THE NORTHERN HALF OF THE REGION. LIGHT SNOW WILL LINGER IN THE EASTERN CWFA INTO THURSDAY EVENING. COLDER AIR PUSHES BACK ACROSS THE CWFA ON FRIDAY. FOR LATE FRIDAY INTO SATURDAY A SYSTEM THAT THE MODELS HAVE TRENDED SOUTH WITH BRUSHES THE FAR SOUTHERN CWFA. THE GFS/DGEX ARE MOST BULLISH WITH QPF WHILE THE ECMWF KEEPS THE FA DRY UNDER SURFACE HIGH PRESSURE... AND THE GEM HAS SOME -SN. MODELS TEND TO AGREE THERE WILL BE SOME WEAK LOW - MID LEVEL ISENTROPIC UPGLIDE. WITH CYCLONIC FLOW IN DEEPENING UPPER TROUGH FEEL LOW END POPS AT THIS POINT OK. THE EXTENDED PERIOD ENDS COLD AND DRY...THE COMMON THEME FOR THIS WINTER. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 712 PM CST SUN FEB 16 2014 CONDITIONS WILL DETERIORATE THROUGH THE OVERNIGHT HOURS...THEN IMPROVE ON MONDAY. THERE IS STILL SOME UNCERTAINTY REGARDING EXACTLY HOW THIS SYSTEM WILL EVOLVE...AND WILL AMEND THE TAFS AS MORE CONFIDENCE IS OBTAINED. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...WINTER WEATHER ADVISORY UNTIL 6 AM CST MONDAY FOR NDZ006>008- 014>016-024-026>030-038-039-049-052>054. MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST MONDAY FOR MNZ001>004-007- 029-030-040. WINTER WEATHER ADVISORY UNTIL 9 AM CST MONDAY FOR MNZ005-006-008- 009-013>017-022>024-027-028-031-032. && $$ UPDATE...TG SHORT TERM...RIDDLE LONG TERM...EWENS/RIDDLE AVIATION...TG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
712 PM CST SUN FEB 16 2014 .UPDATE... ISSUED AT 712 PM CST SUN FEB 16 2014 RADAR IMAGERY INDICATES MODERATE TO HEAVY SNOWFALL ACROSS NORTHCENTRAL NORTH DAKOTA. THE 23Z RAP AND 21Z MPX HOPWRF APPEAR TO HAVE THE BEST HANDLE ON THE CURRENT SITUATION. THE UPPER TROUGH HAS YET TO ENTER THE WESTERN DAKOTAS...AND THIS SLOWER TRANSITION EASTWARD IS LIKELY AFFECTING THE OVERALL PROGRESSION OF THE SYSTEM. THERE IS A LEAD UPPER WAVE RESPONSIBLE FOR THE SNOW ACROSS NC ND...AND THE MAIN UPPER WAVE WILL NOT BE ABLE TO MERGE WITH THE LEAD WAVE. WITH ALL OF THIS SAID...THE RAP DEPICTS MULTIPLE UPPER JET STREAKS MOVING THROUGH THE REGION TONIGHT. PWATS WILL BE 0.4 TO 0.5 INCHES...SO PERIODS OF MODERATE TO HEAVY SNOWFALL STILL LIKELY. FOLLOWING THE 23Z RAP/21 MPX HOPWRF...THE MOST LIKELY WIDESPREAD SNOWFALL WILL BE ACROSS THE DVL BASIN AND NORTHERN VALLEY THROUGH 06Z. AS THE MAIN UPPER TROUGH APPROACHES...EXPECT MORE WIDESPREAD SNOWFALL TO DEVELOP ALONG AND EAST OF THE VALLEY AFTER 06Z. THESE MODELS INDICATE 2-4 INCHES DVL BASIN INTO THE NORTHERN VALLEY THROUGH MIDNIGHT...AND THEN 2-4 INCHES EAST OF THE VALLEY AFTER MIDNIGHT (WITH 1-3 INCHES ELSEWHERE). THIS BASICALLY AGREES WITH THE PREVIOUS FORECAST...BUT JUST A BIT HIGHER ACROSS THE DVL BASIN. SOUTHERLY WINDS CONTINUE TO INCREASE...AND BLOWING SNOW WILL ALSO BE AN ISSUE. && .SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT) ISSUED AT 319 PM CST SUN FEB 16 2014 SNOW AMOUNTS AND TIMING REMAINS THE ISSUE. 12Z MODELS AND SHORT RANGE MODELS BACKED OFF ON TIMING OF MAIN SNOW BAND NOT ARRIVING INTO THE RED RIVER VALLEY TIL 03-06Z AND EASTERN FCST AREA AFTER 06Z. HRRR/RAP/18Z NAM CATCHES ONTO SNOW BANDS IN EASTERN MONTANA DEVELOPING NORTH OF SURFACE LOW IN SOUTHEASTERN MONTANA AND NEAR SHORT WAVE MOVING THRU MONTANA. AHEAD OF THIS MAIN PRECIPITATION BAND IS INITIAL WARM ADVECTION BAND THAT HAS BEEN MOVING EAST SLOWLY THRU WESTERN MANITOBA INTO ERN ND. SNOW WITH THIS BAND LOOKS GOOD ON RADAR BUT OBS INDICATE SNOWFALL PATCHY. UNSURE EXACTLY HOW IT WILL EVOLVE...BUT MAIN UPPER TROUGH IS STILL OVER WRN/CNTRL MONTANA AND ALL MODELS SHOW GOOD UPPER LEVEL DIVERGENCE AHEAD OF IT AND DECENT 700 MB VERTICAL MOTION ALONG WITH GOOD ISENTROPIC LIFT ALONG THE 290K SURFACE AHEAD OF SYSTEM SPREADING INTO ERN ND/NW MN TONIGHT. SO DESPITE A BIT LATER START STILL LOOKING FOR SAME IDEA IN TERMS OF SNOW TOTALS WITH 1-2 FAR WEST TO 3 OR SO IN THE RED RIVER VALLEY TO 4-5 EASTERN FCST AREA. SNOW WILL END IN THE RRV BY 12Z AND IN THE EAST BY 15Z. SOUTH- SOUTHEAST WINDS GUSTY TO 30 KTS AT TIMES THIS AFTN WITH NAM BUFKIT SOUNDINGS INDICATING PEAK MIXING IN LOWEST LAYERS 00Z-03Z IN THE RED RIVER VALLEY WHERE 28-30 KTS AVAILABLE. PUBLIC REPORTS INDICATE LOW LEVEL BLOWING SNOW/DRIFTING AND IN SPOTS POOR VISIBILITY. WILL MAINTAIN THIS IDEA INTO THE EVENING. WHERE SNOW DOES OCCUR WITH WIND NEAR BLIZZARD CONDITIONS WILL OCCUR BUT WINDS APPEAR TO BE BLO BLIZZARD THRESHOLD UNLESS SOMETHING CHANGES. THUS WINTER WX ADVISORY LOOKS GOOD...EVEN FOR WESTERN FCST AREA WHERE SNOW TOTALS ARE BLO ADV THRESHOLDS FOR SNOWFALL. CLEARING WILL MOVE IN MONDAY BEHIND THE FRONT WITH A WEST WIND AND WARMER AIRMASS WITH HIGHS 30-35 IN MOST AREAS MON AFTN. MONDAY NIGHT WILL BE MILD AS WELL WITH TEMPS HOLDING UP WITH WEST BREEZE AND SOME MID LEVEL CLOUDS MOVING BACK IN AS A SHORT WAVE MOVES EAST INTO NORTH DAKOTA. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 319 PM CST SUN FEB 16 2014 AFOREMENTIONED SHORT WAVE WILL MOVE INTO MINNESOTA TUESDAY AND MAY PRODUCE A LITTLE LIGHT SNOW IN THE LAKE OF THE WOODS REGION SO KEPT LOW POPS. OTHERWISE PRETTY MILD AGAIN AS SFC FLOW REMAINS WEST OR SOUTHWEST. HIGH PRESSURE DROPS IN TUES NIGHT...THEN SOUTHEASTERLY FLOW WILL PICK UP WED AFTN AHEAD OF NEXT LOW TO MOVE THROUGH SOUTHERN CANADA. WILL RESTRICT SOME POPS FOR LIGHT SNOW AHEAD OF THIS SYSTEM TO THE AFTN IN NE ND. OR WEDNESDAY NIGHT THROUGH SUNDAY.. LOW AMPLITUDE PROGRESSIVE FLOW BEGINS TO AMPLIFY THIS PERIOD. UPPER RIDGE FORECAST TO REBUILD ALONG 140W WITH TROUGH NEAR 90W. BY THE END OF THE PERIOD THE PATTERN SHIFTS EAST ABOUT 10 DEGREES PUTTING THE NORTHERN PLAINS BACK INTO A COLDER PATTERN. FOR WEDNESDAY EVENING INTO THURSDAY A STRONG LOW TRACKS SLOWLY JUST NORTH OF THE INTERNATIONAL BORDER. LIGHT SNOWS FORECAST AHEAD OF THE FRONT ON THURSDAY IN UPGLIDE ZONE...SIMILAR TO SYSTEM GOING THROUGH REGION TODAY AND TONIGHT. MODELS IN FAIR AGREEMENT THAT WRAP AROUND SNOWS WILL MOVE ACROSS MAINLY THE NORTHERN HALF OF THE REGION. LIGHT SNOW WILL LINGER IN THE EASTERN CWFA INTO THURSDAY EVENING. COLDER AIR PUSHES BACK ACROSS THE CWFA ON FRIDAY. FOR LATE FRIDAY INTO SATURDAY A SYSTEM THAT THE MODELS HAVE TRENDED SOUTH WITH BRUSHES THE FAR SOUTHERN CWFA. THE GFS/DGEX ARE MOST BULLISH WITH QPF WHILE THE ECMWF KEEPS THE FA DRY UNDER SURFACE HIGH PRESSURE... AND THE GEM HAS SOME -SN. MODELS TEND TO AGREE THERE WILL BE SOME WEAK LOW - MID LEVEL ISENTROPIC UPGLIDE. WITH CYCLONIC FLOW IN DEEPENING UPPER TROUGH FEEL LOW END POPS AT THIS POINT OK. THE EXTENDED PERIOD ENDS COLD AND DRY...THE COMMON THEME FOR THIS WINTER. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 712 PM CST SUN FEB 16 2014 CONDITIONS WILL DETERIORATE THROUGH THE OVERNIGHT HOURS...THEN IMPROVE ON MONDAY. THERE IS STILL SOME UNCERTAINTY REGARDING EXACTLY HOW THIS SYSTEM WILL EVOLVE...AND WILL AMEND THE TAFS AS MORE CONFIDENCE IS OBTAINED. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...WINTER WEATHER ADVISORY UNTIL 6 AM CST MONDAY FOR NDZ006>008- 014>016-024-026>030-038-039-049-052>054. MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST MONDAY FOR MNZ001>004-007- 029-030-040. WINTER WEATHER ADVISORY UNTIL 9 AM CST MONDAY FOR MNZ005-006-008- 009-013>017-022>024-027-028-031-032. && $$ UPDATE...TG SHORT TERM...RIDDLE LONG TERM...EWENS/RIDDLE AVIATION...TG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1147 PM CST FRI FEB 14 2014 .UPDATE... ISSUED AT 1146 PM CST FRI FEB 14 2014 TEMPS HAVE BEGUN TO STEADY OR EVEN RISE IN A FEW PLACES WEST OF THE RED RIVER AS CLOUDS AND WINDS PICK UP. THERE ARE SOME RADAR ECHOES DEVELOPING OVER WESTERN ND ALTHOUGH NOT MUCH APPEARS TO BE REACHING THE GROUND YET. THINK IT WILL BE A WHILE BEFORE SATURATION SO KEPT MOST POPS IN THE WEST AFTER 12Z WHICH FITS THE MOST RECENT MODEL RUNS. BETTER CHANCES IN FAR NORTHEASTERN CWA WITH THE NORTHERN SHORTWAVE...SO CONTINUED TO KEEP HIGH POPS IN NORTHERN LAKE OF THE WOODS. UPDATE ISSUED AT 941 PM CST FRI FEB 14 2014 RADAR RETURNS OVER EASTERN MT HAVE BEEN SLOW TO ENTER THE WESTERN PART OF ND AND HAVE SHOWN A BIT OF A WEAKENING TREND. THE 00Z NAM IS QUITE A BIT LESS IMPRESSIVE WITH THE SNOW ENTERING OUR SOUTHEASTERN CWA THAN PREVIOUS RUNS. THE 02Z RAP HAS THE PRECIP DISSIPATING BEFORE IT EVEN ENTERS EASTERN ND. WANT TO GET A LOOK AT THE 00Z GFS AND SEE THE SNOW ENTERING THE WESTERN PART OF THE STATE BEFORE MAKING MORE RADICAL CHANGES TO POPS. FOR NOW...CUT THEM QUITE A BIT FOR TONIGHT...KEEPING ONLY A SMALL SLIVER OUT IN THE WEST BEFORE 12Z. ALSO MADE SOME MINOR ADJUSTEMENTS TO POPS FOR TOMORROW BUT KEPT THE SOUTH AND WEST IN THE LIKELY CATEGORY FOR NOW. TEMP WISE...CLOUDS HAVE KEPT THE NORTHEAST A BIT WARMER THAN EXPECTED WHILE THE SOUTHEAST HAS ALREADY DROPPED BELOW ZERO. THINK THAT THE WESTERN COUNTIES SHOULD START RISING IN A FEW HOURS AS SOUTHERLY WINDS AND CLOUDS MOVE INTO THE REGION. LOWERED LOWS A BIT IN THE SOUTHERN COUNTIES WHERE BWP HAS ALREADY DROPPED TO ZERO. UPDATE ISSUED AT 627 PM CST FRI FEB 14 2014 MADE A FEW MINOR TWEAKS TO MATCH CURRENT CLOUD COVER...BUT NO MAJOR CHANGES FOR THE EARLY EVENING UPDATE. CONTINUE TO THINK WE SHOULD SEE A SHARP DROP OVER THE EASTERN COUNTIES AFTER SUNSET AND THEN RISING TEMPS THROUGHOUT THE AREA FOR THE REST OF THE NIGHT. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 302 PM CST FRI FEB 14 2014 THE MAIN CHALLENGE WILL BE SNOW POTENTIAL TONIGHT INTO SATURDAY MORNING. MODELS ARE IN DECENT AGREEMENT...WITH ONLY MINOR DIFFERENCES WITH QPF AND LOCATION. A COUPLE UPPER WAVES WILL PROPAGATE THROUGH THE REGION LATER TONIGHT INTO SATURDAY. THE STRONGEST FORCING FROM THESE FEATURES WILL MAINLY AFFECT THE SW FA AND THE NE FA. MODELS KEEP THE FORCING FROM THESE FEATURES SEPARATE UNTIL EAST OF THE REGION. THUS...EXPECT AROUND AN INCH OF SNOWFALL ACROSS THESE AREAS (POSSIBLY A BIT HIGHER FOR NORTHERN LAKE OF THE WOODS COUNTY). TEMPERATURES TONIGHT WILL LIKELY FALL UNTIL CLOUDS ARRIVE...THEN STEADY OR SLOWLY RISE. USED THE CONSSHORT GUIDANCE FOR HOURLY VALUES. HIGH PRESSURE MOVES THROUGH THE REGION SATURDAY NIGHT...THUS LOWERED MIN TEMPS A FEW DEGREES. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 302 PM CST FRI FEB 14 2014 SUNDAY-MONDAY...UPPER FLOW WILL BECOME ZONAL AHEAD OF THE NEXT UPPER WAVE. MODELS ALL INDICATE A PERIOD OF 850MB WARM AIR ADVECTION SNOW THAT WILL MOVE THROUGH THE AREA SUNDAY AFTERNOON/NIGHT ASSOCIATED WITH THE UPPER WAVE. THERE IS STILL SOME DISAGREEMENT WITH EXACTLY HOW/WHEN THIS EVENT WILL UNFOLD...AND EXACTLY WHERE THE HEAVIEST SNOWFALL WILL BE LOCATED. AT ANY RATE...1-3 INCHES MOST AREAS...POSSIBLY SLIGHTLY MORE ACROSS THE SOUTHEAST FA. AHEAD OF THE SNOW...SOUTHERLY WINDS WILL BE BREEZY (SUNDAY AFTERNOON). MUCH LIKE PAST SOUTHERLY WIND EVENTS...ANTICIPATE AT LEAST PATCHY BLOWING SNOW ACROSS THE NORTHERN RED RIVER VALLEY (AND INSERTED THIS INTO THE FORECAST). SYNOPTIC PATTERN IS SUCH THAT LOW LEVEL WESTERLY FLOW...AND A WARMER AIRMASS...SHOULD LEAD TO MAX TEMPS NEAR FREEZING ON MONDAY. MONDAY NIGHT-FRIDAY...LONG TERM WILL SEE A SHIFT FROM A ZONAL PATTERN EARLY IN THE PERIOD TO LONG WAVE TROUGHING OVER ROCKIES BY NEXT WEEKEND. WILL SEE A SERIES OF SHORT WAVE TROUGH/RIDGES MOVE THROUGH IN THE MID WEEK...WITH CHANCES OF SNOW AROUND DAY 6/7. WITH THE ZONAL PATTERN AND UPPER WAVES MOVING ACROSS SRN CANADA...SEEING A LOT OF LOW POPS FOR THE SECOND HALF OF THE PERIOD. BEST CHANCE...HOWEVER...APPEARS TO BE WED NIGHT INTO THU AS A DEEPER WAVE MOVES ACROSS THE NORTHERN TIER. ECMWF SHOWS A LOW MOVING OUT OF WYOMING WED AND INVERTED TROUGH LIFTING INTO THE VALLEY WED NIGHT...HOWEVER PRECIP MAY BE MOSTLY ACROSS THE NORTH OR SOUTHERN MANITOBA. TEMPS WILL BE IN THE LOW 30S FOR MUCH OF THE FIRST HALF OF THE WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1146 PM CST FRI FEB 14 2014 VFR CONDITIONS WILL CONTINUE THROUGH SATURDAY MORNING WITH INCREASING HIGH AND MID LEVEL CLOUDS OVERNIGHT. MODELS BEGIN BRINGING IN SOME MVFR CIGS BEHIND A COLD FRONT LATE MORNING INTO THE AFTERNOON. THERE HAS ALSO BEEN A TREND TOWARDS NORTHERLY WINDS PICKING UP TO AROUND 15 KTS SO BUMPED UP WINDS A BIT. THINK THAT SNOW WILL STAY AWAY FROM TAF SITES AT THIS POINT SO WILL NOT INCLUDE FOR NOW. VFR CONDITIONS WILL RETURN TOWARDS THE END OF THE PERIOD AND WINDS WILL START TO DIMINISH. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...JR SHORT TERM...TG LONG TERM...TG/SPEICHER AVIATION...JR
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
659 PM EST SUN FEB 16 2014 .SYNOPSIS... HIGH PRESSURE WILL MOVE ACROSS THE LOWER LAKES TONIGHT AND MOVE OFF THE MID ATLANTIC COAST MONDAY. A CLIPPER SYSTEM WILL TRACK ACROSS THE FORECAST AREA MONDAY AFTERNOON INTO MONDAY NIGHT. && .NEAR TERM /THROUGH MONDAY/... RECENT RADAR TRENDS HAVE SHOWN SOME DECREASE IN SNOW SHOWERS SOUTH IF I-76 WHILE SNOW IS FLARING UP AGAIN NEAR CLEVELAND AS THE NEXT PUSH OF MOISTURE SEEN MOVING SE ON THE DTX RADAR ARRIVES. HAVE UPDATED THE FORECAST TO CARRY SNOW SHOWERS FOR MOST OF NE OHIO THROUGH THE FIRST PART OF THE EVENING...WITH ACTIVITY REALLY DECREASING TOWARDS 9 PM AS THE RUC SHOWS MOISTURE DIMINISHING RAPIDLY AFTER THAT TIME. COULD SEE ANOTHER INCH OF SNOW ACROSS MUCH OF THE SNOWBELT...WHILE AREAS FURTHER INLAND WILL STRUGGLE TO GET MORE THAN A FEW TENTHS. CLOUDS HAVE MOSTLY CLEARED NORTH OF LAKE ERIE AS THE HIGH STRENGTHENS TO THE NORTH SO THERE WILL BE AN END TO THE SNOW SHOWERS AS WE PROGRESS THROUGH THE EVENING. PREVIOUS DISCUSSION... REMNANTS OF THE LOW NOW OVER VIRGINIA. MODELS CONTINUE TO MOVE LOW OFF THE MID ATLANTIC COAST THIS EVENING AND THEN DISSIPATE...AS HIGH PRESSURE NOW OVER MIDDLE MISSISSIPPI VALLEY...MOVES ACROSS THE AREA TONIGHT. LAST LINGERING SNOW SHOWERS ACROSS NE OH AND NW PA WILL END THIS EVENING...THOUGH COULD STILL SEE A FEW FLURRIES THROUGH THE EVENING HOURS. HIGH FORECAST TO BE CENTERED OVER FORECAST AREA TOWARD MIDNIGHT LOCAL. AS IT DOES CLOUDS WILL GRADUALLY THIN. OF COURSE CLOUDS FROM NEXT APPROACHING SYSTEM ALREADY INTO WRN INDIANA SO DO NOT THINK SKIES WILL CLEAR OUT. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... TOMORROW WILL START QUIET ENOUGH WITH HIGH PRESSURE OVERHEAD...BUT THAT WILL BE SHORT LIVED. MODELS CONTINUE TO DEVELOP PANHANDLE LOW OVERNIGHT...THEN TRACK IT NORTHEAST ACROSS OHIO TOMORROW EVENING AND THEN LAKE ERIE MONDAY NIGHT. STILL SOME UNCERTAINTY ABOUT ITS EXACT TRACK BUT IT APPEARS THAT MODELS ARE TRACKING LOW ACROSS WESTERN OHIO. SNOW AMOUNTS STILL HOVERING CLOSE TO THE ADVISORY CRITERIA OF 3 TO 5 INCHES. AS QUICKLY AS THE LOW IS FORECAST TO MOVE...AND WITH THE CURRENT TRACK ACROSS LAKE ERIE SHOULD REMAIN BELOW WARNING CRITERIA...BUT WILL NEED TO CONTINUE TO MONITOR. AREAS OF NE OH AND NW PA COULD SEE A BRIEF PERIOD OF SLEET...BUT DID NOT MENTION IN THE WEATHER GRIDS WITH SO MUCH DOUBT AS TO THE PRECISE TRACK AND TIMING OF THE LOW. THIS STORM WILL BE EAST OF THE AREA BY TUESDAY AFTERNOON WITH A PERIOD OF WARM ADVECTION PATTERN SETTING UP FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. THERE COULD BE JUST ENOUGH LIFT TO GENERATE SOME SNOW FLURRIES ACROSS THE EASTERN HALF OF THE REGION TUESDAY NIGHT INTO WEDNESDAY. && .LONG TERM /THURSDAY THROUGH SUNDAY/... THE FIRST PORTION OF THE EXTENDED FORECAST IS SIMILAR ON MOST OF THE MODELS AND IS IN LINE WITH THE CURRENT FORECAST. LOW PRESSURE DEVELOPS ON A FRONT CROSSING THE MIDWEST. WE REMAIN ON THE WARM SIDE OF THE LOW WITH RAIN THURSDAY INTO THURSDAY NIGHT. THUNDER IS NOT OUT OF THE QUESTION BUT IT IS TOO EARLY TO TRY AND GET THAT SPECIFIC WITH THE FORECAST. THE COMBINATION OF SNOW MELT AND RAIN WILL POSE A FLOOD RISK AS WELL AS AN ICE JAM RISK ON THE OUR SLOWER AND COLDER WATERWAYS. BY FRIDAY THE LOW GETS ABSORBED IN THE MAIN SURFACE LOW ACROSS EASTERN CANADA. THE GEM DEVELOPS A SECOND WAVE ON THE FRONT AND IS SLOWER TO END THE PRECIPITATION ACROSS NE OH/NW PA ON FRIDAY AND WILL WATCH TO SEE IF THIS TREND DEVELOPS ON ANY OF THE OTHER PROMINENT MODELS. STILL SOME DIFFERENCES ON THE SYSTEM NEXT WEEKEND. THE GFS AND MOST MODELS BRING THE NEXT COLD FRONT THROUGH LATER SATURDAY...THEN DEVELOP A WAVE ON THE FRONT TO OUR EAST. THIS OPENS THE DOOR FOR A CHANCE FOR A FEW SHOWERS WITH THE FRONTAL PASSAGE AND PERHAPS A CHANCE OF SNOW AS THE COLDER AIR FILTERS IN. THE ECMWF RAPIDLY DEVELOPS A FULL BLOWN SURFACE LOW ACROSS EASTERN OHIO AND IS AN OUTLIER. THE FORECAST WILL KEEP SATURDAY MILD THEN BRING COLDER WEATHER BACK BY SUNDAY. && .AVIATION /00Z TUESDAY THROUGH FRIDAY/... A RIDGE WILL MOVE WEST TO EAST ACROSS THE REGION TONIGHT AND MONDAY MORNING. THE LAKE EFFECT CLOUDS/FLURRIES AND SNOW SHOWERS WERE DECREASING QUICKLY THIS EVENING. THE BIG QUESTION IS WILL SOME FOG FORM. HIGHS CLOUDS WILL BE MOVING IN OVERNIGHT ESPECIALLY FOR THE SOUTHERN PORTION OF THE FORECAST AREA. THIS MAY INHIBIT THE FOG SOME. MENTIONED FOG IN THE TAFS ESPECIALLY CLOSE TO THE LAKESHORE AND IN THE MANSFIELD AREA. IN FACT SOME STRATUS COULD COME IN OFF OF LAKE ERIE INTO TOLEDO IN THE EASTERLY FLOW. FOR MONDAY ANY FOG WILL BURN OFF QUICKLY. THE CLOUDS WILL CONTINUE TO THICKEN AND LOWER. SOME QUESTION HOW QUICKLY THE SNOW WILL COME IN. AT THIS TIME LEANING TOWARD LATE AFTERNOON FOR NW OHIO. THE SNOW SHOULD SPREAD EAST QUICKLY. OUTLOOK...NON-VFR MONDAY NIGHT LASTING INTO TUESDAY. NON-VFR LIKELY REDEVELOPING THURSDAY AND THURSDAY NIGHT. && .MARINE... THE WEATHER PATTERN WILL BECOME MUCH MORE ACTIVE THIS WEEK WITH STRONGER WINDS AND WIND SHIFTS ON LAKE ERIE. NORTH WINDS WILL VEER TOWARD THE EAST AND SOUTHEAST BY MONDAY MORNING. THE EAST TO SOUTHEAST WIND WILL BECOME RATHER BRISK MONDAY AFTERNOON ON THE WESTERN BASIN. WINDS WILL SHIFT TO SOUTHWEST AS THE LOW PRESSURE SYSTEM GOES BY ON MONDAY NIGHT. WE COULD SEE 25 TO 30 KNOTS TUESDAY MORNING. THE NEXT COLD FRONT COMES QUICK...WEDNESDAY MORNING...AND WINDS WILL NOT HAVE MUCH CHANCE TO SETTLE DOWN. THERE COULD BE A BREAK FOR A SHORT TIME WEDNESDAY NIGHT AS HIGH PRESSURE CROSSES THE OHIO VALLEY. THE NEXT LOW PRESSURE SYSTEM WILL BE STRONGER AND WINDS WILL ONCE AGAIN REACH 25 TO PERHAPS 30 KNOTS BY THURSDAY NIGHT AND FRIDAY. WITH WARMER TEMPERATURES...THE ICE WILL LIKELY BEGIN TO SHIFT AND MOVE LATER IN THE WEEK. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...DJB NEAR TERM...DJB/KEC SHORT TERM...DJB LONG TERM...KOSARIK AVIATION...KIELTYKA MARINE...KOSARIK
AREA FORECAST DISCUSSION
NWS NORMAN OK
916 PM CST SUN FEB 16 2014 .UPDATE... THE HRRR SEEMS TO HAVE A DECENT HANDLE ON THE WESTERN AND NORTHERN EXTENT OF NEAR SURFACE MOISTURE. CLOUD COVER AND WINDS SHOULD KEEP DENSE FOG FAIRLY LOW TONIGHT. HOWEVER...AS BETTER MOISTURE REACHES FAR NORTHERN OK LATE THIS EVENING...SOME PATCHY DENSE FOG MAY FORM FOR A FEW HOURS NEAR ALVA...CHEROKEE ETC. AS WINDS INCREASE AND SHIFT OVERNIGHT...ANY FOG WILL BE REMOVED. WILL EXTEND PATCHY FOG A LITTLE NORTH AND WEST...GENERALLY THROUGH ABOUT 8-10Z. && .DISCUSSION... && .PREV DISCUSSION... /ISSUED 512 PM CST SUN FEB 16 2014/ AVIATION... MVFR... THEN IFR CEILINGS EXPECTED TO DEVELOP QUICKLY THIS EVENING NEAR THE I-35 CORRIDOR... AFFECTING OKC/OUN/PNC. ALONG WITH THIS IS THE POSSIBILITY OF FOG CREATING MFVR VIS AS WELL. PATCHY DRIZZLE MAY ALSO OCCUR... BUT CHANCE NOT HIGH ENOUGH AT THIS TIME TO INCLUDE. SFC WINDS EXPECTED TO VEER AHEAD OF STRONG COLD FRONT LATE TONIGHT... WHICH SHOULD SCOUR OUT THE LOW LEVEL MOISTURE AND ALLOW VFR CONDITIONS TO DEVELOP AT ALL SITES. STRONG... GUSTY NORTH WINDS WILL OCCUR BEHIND THE FRONT WITH GUSTS OVER 30KTS. WINDS WILL DIMINISH QUICKLY DURING THE AFTN HOURS TOMORROW. 30 PREV DISCUSSION... /ISSUED 417 PM CST SUN FEB 16 2014/ DISCUSSION... ONLY A SMALL AREA OF STRATUS REMAINS NEAR ARDMORE THIS AFTERNOON. HOWEVER...IT WILL QUICKLY RETURN EARLY THIS EVENING AND SPREAD NORTHWARD OVER CENTRAL AND EASTERN OK. MOST WIND SPEEDS WILL REMAIN AROUND 10 TO 15 KT THROUGH THE EVENING...BUT EXPECT AT LEAST SOME PATCHY FOG TO DEVELOP ON THE WESTERN EDGE OF THE STRATUS OVER CENTRAL OK ALONG I35. THE FOG WILL LIKELY COME EARLY (AROUND 06Z) AND END QUICKLY (BEFORE SUNRISE). THIS WILL BE NEAR A SFC TROUGH AHEAD OF THE APPROACHING COLD FRONT. ALSO...SOME DRIZZLE STILL APPEARS LIKELY ACROSS OUR EXTREME E/SE ZONES BEFORE THE LOW LEVEL FLOW QUICKLY VEERS BY SUNRISE. TEMPS WILL STILL REMAIN AROUND 5 DEGREES ABOVE AVG TOMORROW AFTERNOON BEHIND THE FRONT AS SKIES QUICKLY CLEAR. THE SURFACE HIGH WILL QUICKLY MOVE E/SE OVERNIGHT MONDAY AND SW SFC FLOW WILL RETURN OVER THE AREA TUES QUICKLY WARMING THINGS BACK UP WELL ABOVE NORMAL. RAPID MOISTURE RETURN IS STILL ANTICIPATED BY WED AS A PRESSURE FALLS INCREASE IN THE LEE OF THE ROCKIES AHEAD OF A SOUTHERN STREAM PAC SHORTWAVE TROUGH AND A DIGGING INTERMOUNTAIN WEST SHORTWAVE TROUGH. THE INITIAL SOUTHERN TROUGH WILL PASS OVERHEAD WED. THE LIFT ASSOCIATED WITH THIS FEATURE WILL COMBINE WITH STRONG ISENTROPIC ASCENT TO PRODUCE SOME SHOWERS AND THUNDERSTORMS WITHIN AN UNSEASONABLY MOIST AIR ACROSS CENTRAL AND EASTERN OK. FOR THE MOMENT...WILL KEEP HIGHEST POPS ACROSS THE N/NE WHERE THE MOST SIGNIFICANT LIFT IS ANTICIPATED NEAR DRYLINE/COLD FRONT INTERSECTION AND THE SFC LOW. THE STRONGEST COLD FRONT OVER THE NEXT 7 DAYS WILL ACCOMPANY A MID TO UPPER TROUGH SWINGING OVER THE MIDWEST NEXT SATURDAY...ALTHOUGH IT APPEARS IT WILL REMAIN DRY AROUND HERE. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 48 62 37 69 / 10 0 0 0 HOBART OK 45 63 35 69 / 0 0 0 0 WICHITA FALLS TX 48 67 38 73 / 0 0 0 0 GAGE OK 40 61 33 68 / 0 0 0 0 PONCA CITY OK 45 60 35 67 / 10 0 0 0 DURANT OK 58 69 40 71 / 10 10 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
936 PM EST SUN FEB 16 2014 .SYNOPSIS... HIGH PRESSURE WILL BUILD INTO CENTRAL PA TONIGHT AND MONDAY. AN AREA OF LOW PRESSURE WILL MOVE THROUGH THE REGION MONDAY NIGHT AND TUESDAY MORNING...BRINGING A WIDESPREAD MODERATE ACCUMULATION OF SNOW. TEMPERATURES WILL GRADUALLY WARM THROUGH THE UPCOMING WEEK...AS A SERIES OF STORM SYSTEMS MOVE THROUGH AND PULL WARMER AIR INTO THE AREA. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... WATER VAPOR LOOP SHOWS POTENT SHORTWAVE EXITING PA THIS EVENING. LARGE SCALE SUBSIDENCE IN THE WAKE OF THIS FEATURE IS PRODUCING CLEARING SKIES ACROSS MUCH OF CENTRAL PA AS OF 02Z. OROGRAPHIC FORCING OF RESIDUAL LOW LVL MOISTURE CONTINUES TO PRODUCE LGT SNOW SHOWERS ACROSS THE LAUREL HIGHLANDS...BUT EVEN THERE EXPECT CLEARING SKIES LATER TONIGHT...AS HIGH PRES BUILDS IN FROM THE GRT LKS. TIGHTENING PRES GRAD BTWN DEPARTING WEAK SFC LOW AND UPSTREAM HIGH IS CREATING INCREASING WINDS ACROSS THE CENTRAL MTNS LATE THIS EVENING WITH GUSTS TO ARND 20KTS. HOWEVER...EXPECT WINDS TO DIMINISH TOWARDS DAWN...AS SFC HIGH ARRIVES. NEARLY PERFECT CONDS FOR RADIATIONAL COOLING ACROSS WESTERN PA LATE TONIGHT...WITH SFC HIGH OVERHEAD AND DEEP SNOW COVER. THUS...HAVE CONTINUED THE TREND OF UNDERCUTTING MOS BY BLENDING WITH LATEST RAP GUIDANCE. TEMPS ACROSS THE NW MTNS SHOULD EASILY FALL BLW ZERO AND WIDESPREAD SINGLE DIGITS APPEAR LIKELY EVEN ACROSS THE LOWER SUSQ VALLEY. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... HIGH PRES AND ASSOC DRY AIR MASS SHOULD PROVIDE CENTRAL PA WITH A SUNNY AND NEARLY CALM MORNING. WAA ALOFT IN ADVANCE OF NEXT SHORTWAVE SHOULD SPREAD HIGH CLOUDS INTO THE AREA BY AFTN. ALL MDLS AND ENSEMBLE MEMBERS HOLD THE SNOW OFF UNTIL AFTER 00Z TUES. TEMPS GET BACK INTO THE M/U20S BY AFTN...BUT WILL STAY 10 TO 12F BELOW NORMALS WITH ALL THAT SNOW ON THE GROUND FOR THE DIMINISHING SUNSHINE TO WORK ON. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... 12Z GFS NOW IN BETTER AGREEMENT WITH ECMWF OF EVOLUTION OF SHORTWAVE /DROPPING OUT OF THE CENTRAL ROCKIES THIS SUNDAY EVENING/ DIGGING QUICKLY TO THE ESE ACROSS THE CENTRAL PLAINS DURING THE DAY MONDAY...BEFORE IMPACTING OUR LOCAL WEATHER WITH ANOTHER 6-9 HOUR PERIOD OF SNOW BEGINNING MONDAY EVE THROUGH THE MID MORNING HOURS OF TUESDAY. LATEST GUIDANCE CONTINUES TO CENTER AROUND A FAIRLY WIDESPREAD 0.10-0.20 SWATH OF QPF...WHICH AT 15:1 RATIO SH OULD TRANSLATE INTO A 2-4 INCH SNOWFALL FOR MOST AREAS...A LITTLE LESS NEAR 1-3 ACROSS THE SOUTH. BEST PERIOD OF MODERATE SNOWS WILL BE FROM 06-12Z TUE...AS 100 KT UPPER JET STREAK SLIDES BY OVER A POTENT 40-45KT MEAN 925-850 MB SRLY JET. THOUGH LATEST SREF AND WPC GUIDANCE SUGGESTS LESS POTENTIAL FOR LIGHT FZRA ACROSS SOUTHERN TIER...HAVE TO RESPECT THE STRENGTH OF THE LOW LEVEL JET...SO MAINTAINED MENTION IN FCST FOR NOW. AFTER COLLABORATION WITH NEIGHBORING OFFICES...AGREED THAT IS IT STILL A BIT EARLY TO ISSUE AN ADVISORY FOR MON EVE INTO TUE /3RD PERIOD/...BUT POPS REMAIN HIGH AS CONFIDENCE CONTINUES TO INCREASE IN THIS PORTION OF THE FORECAST. WARMING LOW CLOUDS...AND THE QUICK DEPARTURE OF THE SEEDER-FEEDER HIGHER CLOUD DECK LATER TUESDAY MORNING COULD LEAD TO SOME LINGERING LIGHT FZDZ /ESPECIALLY ACROSS THE SOUTH AND WEST/. AFTER TUES...MODELS ALSO KEEPING TREND OF COMING MORE INTO OVERALL AGREEMENT...AT LEAST UNTIL THE WEEKEND. ANOTHER VERY WEAK DIP IN THE TROUGH SLIPS THROUGH ON WED IN FAST FLOW BRINGING A WEAKENING COLD FRONTAL PASSAGE...BUT PRECIP WILL BE VERY LIGHT OR TOUGH TO COME BY AT ALL. THEN A NOTICEABLE WARM-UP BEGINS FOR THE LATE WEEK AS THE PATTERN BEGINS TO MODIFY WITH A BROAD UPPER TROUGH FORMING OVER THE ROCKIES...FINALLY BRINGING SW FLOW...WAA...AND RISING HEIGHTS. DID SHAVE A FEW DEGREES OFF OF MID/LATE WEEK TEMPS...BUT STILL EXPECTING HIGHS GENERALLY REACHING THE 40S WED-FRI WITH MILDER LOWS AS WE REMAIN ON THE WARM SIDE OF A SYSTEM ROTATING AROUND LOW CENTERED OVER UPPER GREAT LAKES. COLD FRONT ASSOCIATED WITH THAT SYSTEM WILL EXTEND SOUTH ACROSS THE MIDWEST AND WILL BE DIVIDING LINE BETWEEN WARM AIR AND COLD AIR. WARM FRONTAL BOUNDARY AHEAD OF IT WILL BRING INCREASING CHANCES FOR A WIDESPREAD RAIN EVENT LATER THU INTO EARLY FRI...WITH QPF AROUND 0.50. WITH SOUTHERLY FLOW BRINGING WARMER AIR OVER THE SNOWPACK THU NIGHT...SHOULD SEE DECENT AMOUNT OF FOG DEVELOP. RAIN WILL MOVE IN FROM THE WEST LATE THU...IMPACTING MUCH OF CENTRAL PA THU NIGHT BEFORE COLD FRONT SLOGS THROUGH ON FRI PUSHING PRECIP EASTWARD. BEHIND THE FRONT...AIR ONLY SLIGHTLY COLDER BUT SERIES OF WEAKER WAVES WILL AGAIN CARVE OUT A BROAD TROUGH OVER THE GLAKES AND GIVE US A COUPLE REINFORCING SHOTS OF COOLER AIR. POTENTIAL FOR ANOTHER MORE NOTABLE WAVE TO SLIDES THROUGH OVER THE WEEKEND /AS HINTED IN THE ECMWF/ IN THIS ACTIVE WEATHER PATTERN. WAY TOO MANY WEATHER FEATURES BETWEEN NOW AND THEN TO GET WORKED UP ABOUT THAT ONE ATTM. WITH THE WARMING TREND...WILL NEED TO MONITOR ISSUES RELATED TO ACCELERATED MELTING OF SNOW COVER AND RIVER ICE. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... SNOW SHOWERS AND FLURRIES ASSOCD WITH WEAK TROUGH ALOFT WILL DECREASE OVER CENTRAL PA AIRFIELDS THIS EVENING. IFR LIKELY FOR BFD/JST THROUGH MID EVENING...WITH MVFR CIGS ELSEWHERE ACROSS CENTRAL AIRFIELDS...AND GENERALLY VFR FOR SOUTHEAST TAF SITES. STRONG SUBSIDENCE TONIGHT WILL LEAD TO SUBSTANTIAL CLEARING. WIND WILL NOT TOALLY DIE OFF IN MOST PLACES...BUT MAY BECOME CALM IN THE DEEPEST VALLEYS. EXPECT VFR FROM LATE TONIGHT INTO EARLY EVENING ON MONDAY. JUST AFTER 00Z TUESDAY...ANOTHER SYSTEM WILL START TO MAKE ITS WAY THROUGH PENNSYLVANIA...BRINGING IFR TO LIFR CONDITIONS. THIS MONDAY NIGHT SHOT WILL PRODUCE A 6-12 HOUR PERIOD OF SNOW EVERYWHERE. SOME IP/ZR IS POSSIBLE ACROSS THE SRN TIER AS WARM AIR BRIEFLY MOVES IN ALOFT. MOST PRECIP WILL BE TO THE EAST OF THE AREA BEFORE NOON ON TUES. OUTLOOK... WED...NO SIG WX. FOG POSS. THU...FOG WITH WINTRY MIX TURNING TO RAIN. REDUCTIONS LIKELY. FRI...SHRA THEN CFOPA...THEN SHSN W. BREEZY. IFR/MVFR LIKELY. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO NEAR TERM...FITZGERALD SHORT TERM...DANGELO/FITZGERALD LONG TERM...RXR AVIATION...DANGELO/DEVOIR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
839 PM EST SUN FEB 16 2014 .SYNOPSIS... HIGH PRESSURE WILL BUILD INTO CENTRAL PA TONIGHT AND MONDAY. AN AREA OF LOW PRESSURE WILL MOVE THROUGH THE REGION MONDAY NIGHT AND TUESDAY MORNING...BRINGING A WIDESPREAD MODERATE ACCUMULATION OF SNOW. TEMPERATURES WILL GRADUALLY WARM THROUGH THE UPCOMING WEEK...AS A SERIES OF STORM SYSTEMS MOVE THROUGH AND PULL WARMER AIR INTO THE AREA. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... WATER VAPOR LOOP SHOWS POTENT SHORTWAVE EXITING PA THIS EVENING. LARGE SCALE SUBSIDENCE IN THE WAKE OF THIS FEATURE IS PRODUCING CLEARING SKIES ACROSS MUCH OF CENTRAL PA AS OF 01Z. OROGRAPHIC FORCING OF RESIDUAL LOW LVL MOISTURE CONTINUES TO PRODUCE LGT SNOW ACROSS THE LAUREL HIGHLANDS...BUT EVEN THERE EXPECT CLEARING SKIES LATER TONIGHT...AS HIGH PRES BUILDS IN FROM THE GRT LKS. VSBYS RAPIDLY RISING ACROSS SW PA AT 01Z...SO WILL LET WINT WX ADVISORY DIE AT 02Z ACROSS SOMERSET CO. PRES GRADIENT WILL TIGHTEN THIS EVENING BTWN DEPARTING WEAK SFC LOW AND UPSTREAM HIGH. OBS ACROSS THE W MTNS ALREADY SHOWING INCREASING WGUSTS TO ARND 20KTS. HOWEVER...EXPECT WINDS TO DIMINISH TOWARDS DAWN...AS SFC HIGH ARRIVES. NEARLY PERFECT CONDS FOR RADIATIONAL COOLING ACROSS WESTERN PA LATE TONIGHT...WITH SFC HIGH OVERHEAD AND DEEP SNOW COVER. THUS...HAVE CONTINUED THE TREND OF UNDERCUTTING MOS BY BLENDING WITH LATEST RAP GUIDANCE. TEMPS ACROSS THE NW MTNS SHOULD EASILY FALL BLW ZERO AND WIDESPREAD SINGLE DIGITS APPEAR LIKELY EVEN ACROSS THE LOWER SUSQ VALLEY. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... HIGH PRES AND ASSOC DRY AIR MASS SHOULD PROVIDE CENTRAL PA WITH A SUNNY AND NEARLY CALM MORNING. WAA ALOFT IN ADVANCE OF NEXT SHORTWAVE SHOULD SPREAD HIGH CLOUDS INTO THE AREA BY AFTN. ALL MDLS AND ENSEMBLE MEMBERS HOLD THE SNOW OFF UNTIL AFTER 00Z TUES. TEMPS GET BACK INTO THE M/U20S BY AFTN...BUT WILL STAY 10 TO 12F BELOW NORMALS WITH ALL THAT SNOW ON THE GROUND FOR THE DIMINISHING SUNSHINE TO WORK ON. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... 12Z GFS NOW IN BETTER AGREEMENT WITH ECMWF OF EVOLUTION OF SHORTWAVE /DROPPING OUT OF THE CENTRAL ROCKIES THIS SUNDAY EVENING/ DIGGING QUICKLY TO THE ESE ACROSS THE CENTRAL PLAINS DURING THE DAY MONDAY...BEFORE IMPACTING OUR LOCAL WEATHER WITH ANOTHER 6-9 HOUR PERIOD OF SNOW BEGINNING MONDAY EVE THROUGH THE MID MORNING HOURS OF TUESDAY. LATEST GUIDANCE CONTINUES TO CENTER AROUND A FAIRLY WIDESPREAD 0.10-0.20 SWATH OF QPF...WHICH AT 15:1 RATIO SH OULD TRANSLATE INTO A 2-4 INCH SNOWFALL FOR MOST AREAS...A LITTLE LESS NEAR 1-3 ACROSS THE SOUTH. BEST PERIOD OF MODERATE SNOWS WILL BE FROM 06-12Z TUE...AS 100 KT UPPER JET STREAK SLIDES BY OVER A POTENT 40-45KT MEAN 925-850 MB SRLY JET. THOUGH LATEST SREF AND WPC GUIDANCE SUGGESTS LESS POTENTIAL FOR LIGHT FZRA ACROSS SOUTHERN TIER...HAVE TO RESPECT THE STRENGTH OF THE LOW LEVEL JET...SO MAINTAINED MENTION IN FCST FOR NOW. AFTER COLLABORATION WITH NEIGHBORING OFFICES...AGREED THAT IS IT STILL A BIT EARLY TO ISSUE AN ADVISORY FOR MON EVE INTO TUE /3RD PERIOD/...BUT POPS REMAIN HIGH AS CONFIDENCE CONTINUES TO INCREASE IN THIS PORTION OF THE FORECAST. WARMING LOW CLOUDS...AND THE QUICK DEPARTURE OF THE SEEDER-FEEDER HIGHER CLOUD DECK LATER TUESDAY MORNING COULD LEAD TO SOME LINGERING LIGHT FZDZ /ESPECIALLY ACROSS THE SOUTH AND WEST/. AFTER TUES...MODELS ALSO KEEPING TREND OF COMING MORE INTO OVERALL AGREEMENT...AT LEAST UNTIL THE WEEKEND. ANOTHER VERY WEAK DIP IN THE TROUGH SLIPS THROUGH ON WED IN FAST FLOW BRINGING A WEAKENING COLD FRONTAL PASSAGE...BUT PRECIP WILL BE VERY LIGHT OR TOUGH TO COME BY AT ALL. THEN A NOTICEABLE WARM-UP BEGINS FOR THE LATE WEEK AS THE PATTERN BEGINS TO MODIFY WITH A BROAD UPPER TROUGH FORMING OVER THE ROCKIES...FINALLY BRINGING SW FLOW...WAA...AND RISING HEIGHTS. DID SHAVE A FEW DEGREES OFF OF MID/LATE WEEK TEMPS...BUT STILL EXPECTING HIGHS GENERALLY REACHING THE 40S WED-FRI WITH MILDER LOWS AS WE REMAIN ON THE WARM SIDE OF A SYSTEM ROTATING AROUND LOW CENTERED OVER UPPER GREAT LAKES. COLD FRONT ASSOCIATED WITH THAT SYSTEM WILL EXTEND SOUTH ACROSS THE MIDWEST AND WILL BE DIVIDING LINE BETWEEN WARM AIR AND COLD AIR. WARM FRONTAL BOUNDARY AHEAD OF IT WILL BRING INCREASING CHANCES FOR A WIDESPREAD RAIN EVENT LATER THU INTO EARLY FRI...WITH QPF AROUND 0.50. WITH SOUTHERLY FLOW BRINGING WARMER AIR OVER THE SNOWPACK THU NIGHT...SHOULD SEE DECENT AMOUNT OF FOG DEVELOP. RAIN WILL MOVE IN FROM THE WEST LATE THU...IMPACTING MUCH OF CENTRAL PA THU NIGHT BEFORE COLD FRONT SLOGS THROUGH ON FRI PUSHING PRECIP EASTWARD. BEHIND THE FRONT...AIR ONLY SLIGHTLY COLDER BUT SERIES OF WEAKER WAVES WILL AGAIN CARVE OUT A BROAD TROUGH OVER THE GLAKES AND GIVE US A COUPLE REINFORCING SHOTS OF COOLER AIR. POTENTIAL FOR ANOTHER MORE NOTABLE WAVE TO SLIDES THROUGH OVER THE WEEKEND /AS HINTED IN THE ECMWF/ IN THIS ACTIVE WEATHER PATTERN. WAY TOO MANY WEATHER FEATURES BETWEEN NOW AND THEN TO GET WORKED UP ABOUT THAT ONE ATTM. WITH THE WARMING TREND...WILL NEED TO MONITOR ISSUES RELATED TO ACCELERATED MELTING OF SNOW COVER AND RIVER ICE. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... SNOW SHOWERS AND FLURRIES ASSOCD WITH WEAK TROUGH ALOFT WILL DECREASE OVER CENTRAL PA AIRFIELDS THIS EVENING. IFR LIKELY FOR BFD/JST THROUGH MID EVENING...WITH MVFR CIGS ELSEWHERE ACROSS CENTRAL AIRFIELDS...AND GENERALLY VFR FOR SOUTHEAST TAF SITES. STRONG SUBSIDENCE TONIGHT WILL LEAD TO SUBSTANTIAL CLEARING. WIND WILL NOT TOALLY DIE OFF IN MOST PLACES...BUT MAY BECOME CALM IN THE DEEPEST VALLEYS. EXPECT VFR FROM LATE TONIGHT INTO EARLY EVENING ON MONDAY. JUST AFTER 00Z TUESDAY...ANOTHER SYSTEM WILL START TO MAKE ITS WAY THROUGH PENNSYLVANIA...BRINGING IFR TO LIFR CONDITIONS. THIS MONDAY NIGHT SHOT WILL PRODUCE A 6-12 HOUR PERIOD OF SNOW EVERYWHERE. SOME IP/ZR IS POSSIBLE ACROSS THE SRN TIER AS WARM AIR BRIEFLY MOVES IN ALOFT. MOST PRECIP WILL BE TO THE EAST OF THE AREA BEFORE NOON ON TUES. OUTLOOK... WED...NO SIG WX. FOG POSS. THU...FOG WITH WINTRY MIX TURNING TO RAIN. REDUCTIONS LIKELY. FRI...SHRA THEN CFOPA...THEN SHSN W. BREEZY. IFR/MVFR LIKELY. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 9 PM EST THIS EVENING FOR PAZ033. && $$ SYNOPSIS...DANGELO NEAR TERM...FITZGERALD SHORT TERM...DANGELO/FITZGERALD LONG TERM...RXR AVIATION...DANGELO/DEVOIR
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1245 AM EST SAT FEB 15 2014 .SYNOPSIS... AN UPPER LEVEL SYSTEM WILL QUICKLY MOVE OFF THE MID ATLANTIC COAST TODAY AS HIGH PRESSURE BUILDS IN FROM THE WEST. A COLD FRONT WILL REACH OUR AREA FROM THE WEST MONDAY NIGHT ON TUESDAY. EXPECT A SOUTHERLY WIND FLOW TO BRING MUCH ABOVE NORMAL TEMPERATURES LATE IN THE WEEK. && .NEAR TERM /THROUGH TODAY/... 930 PM UPDATE...PATCHES OF LIGHT PRECIP SEEN ON RADARS ATTM FROM FAR ERN KY AND SRN WV DOWN THRU THE GREAT VALLEY AND INTO ERN AL. THESE ARE ALL AHEAD OF THE UPPER SHORTWAVE. SFC OBS INDICATE RATES OF A FEW HUNDREDTHS PER HOUR. SPC MESOANALYSIS SUGGESTS THE NE ALABAMA ACTIVITY...WHICH PER TRENDS WOULD AFFECT OUR CWFA THE MOST...IS OCCURRING IN AN AREA OF WEAK WARM UPGLIDE AHEAD OF THE BASE OF THE 850MB TROUGH. RUC PROGS SUGGEST THIS FORCING DIVES SEWD ACRS GA AND INTO THE SC MIDLANDS...BUT THEY STILL SHOW SOME LIGHT QPF CROSSING THE FA DIRECTLY AHEAD OF THE UPPER WAVE AND REASONABLY CLOSE TO EARLIER TIMING. TWEAKED POPS DOWNWARD THIS EVENING TO ACCOUNT FOR THE SPOTTY NATURE OF THE ACTIVITY NOW ENTERING SW NC AND NE GA...BUT OVERALL POPS LOOK REASONABLE...AND THE PRECIP RATES SUGGESTED BY THE GOING QPF ARE OK. 00Z NAM SEEMS TO MOVE THE PRECIP OUT FASTER TOMORROW MORNING. TEMPS AND DEWPOINTS WERE OK BUT DID TOUCH THEM UP ONCE AGAIN PER SHORT TERM CONSENSUS GUIDANCE. NEW TEMPS ARE SOMEWHAT WARMER ESPECIALLY EARLY IN THE EVENT IN THE MTNS...WHICH REDUCES THE STORM TOTAL SNOWFALL IN SOME PLACES DUE TO HIGHER SNOW LEVELS THIS EVENING. WILL REISSUE WSW PRODUCT SHORTLY BUT WORDING WILL LIKELY BE VERY CLOSE TO THAT ALREADY USED. 700 PM UPDATE...REVISED POPS...AND TO A LESSER EXTENT QPF... FOLLOWING THE 18Z NAM/GFS AND 15Z SREF. THE MODELS GENERALLY AGREE ON A WAVE OF PRECIP PASSING THRU THE PIEDMONT BEFORE DAYBREAK. ISENTROPIC FORCING DOES LOOK PRETTY LIMITED BUT IT IS HARD TO IGNORE THE DYNAMIC LIFT AND DEEP COLUMN OF MOISTURE PROGGED TO CROSS WITH THE SHORTWAVE. ALSO RECALL THAT THE TRACK OF THIS WAVE IS PRETTY SIMILAR TO THAT THURSDAY MORNING...WHICH THE NAM/GFS CORRECTLY INDICATED WOULD BRING PRECIP TO THE PIEDMONT IN ITS DEFORMATION ZONE. THUS FELT CONFIDENT ENOUGH TO GO CATEGORICAL...IF NOT BRIEFLY...IN A BAND TRAVERSING THE CWFA. QPF STILL LOOKED PRETTY GOOD BUT MADE CHANGES MAINLY EAST OF THE SNOW AREA. IT CONTINUES TO LOOK LIKE THE COLDER AIR CAPABLE OF ALLOWING SNOW TO REACH THE SURFACE EAST OF THE MTNS/FOOTHILLS WILL NOT PUSH IN FAST ENOUGH TO ALLOW MUCH SNOW ACCUMULATION. SNOW MENTION IS A BIT LESS EXPANSIVE OVER THE NC PIEDMONT AS A RESULT. IN THE MTNS...ACCUMS ARE PRETTY SIMILAR WITH THE ONLY TOTALS ABOVE ADVY CRITERIA SHOWN IN THE HIGHEST ELEVATIONS. TEMP/DEWPT TRENDS FROM EARLIER UPDATE STILL LOOK TO BE ON TRACK. ON ANOTHER NOTE...TAKING ANOTHER LOOK AT WINDS SUNDAY...THE GRADIENT APPEARS TO RELAX FAST ENOUGH TO ALLOW THE WIND ADVY TO EXPIRE MUCH EARLIER THAN PREVIOUSLY THOUGHT. WILL TRIM IT BACK TO END SATURDAY EVENING. AT 215 PM EST FRIDAY...A STRONG SHORTWAVE WILL DIVE INTO THE BASE OF AN EASTERN NORTH AMERICAN TROUGH TONIGHT...REACHING THE CENTRAL CAROLINAS BY SATURDAY MORNING. THIS SHORTWAVE WILL MOVE UP THE EAST COAST ON SATURDAY. MODEST ISENTROPIC UPGLIDE WILL SPREAD OVER THE MOUNTAINS ATE THIS EVENING...AND THE FOOTHILLS AND PIEDMONT SHORTLY THEREAFTER... SUPPORTING THE DEVELOPMENT OF PRECIPITATION AHEAD OF AN APPROACHING COLD FRONT. MODEL SOUNDINGS SHOW MOISTURE EXTENDING TO LEVELS COLD ENOUGH FOR ICE NUCLEATION...BUT LOWER LEVELS WILL INITIALLY BE WARM ENOUGH FOR RAIN. WITH NO WARM NOSE ALOFT...THIS WILL BE A RAIN/SNOW SETUP. AS THE NIGHT PROGRESSES...SNOW LEVELS FALL TO THE FLOORS OF THE MOUNTAINS VALLEYS...AND BRIEFLY TO THE SURFACE IN THE LEE OF THE MOUNTAINS...MAINLY IN WESTERN NC. MINIMUM TEMPERATURES ARE EXPECTED TO BE NEAR NORMAL...AND ABOVE FREEZING EAST OF THE MOUNTAINS. SNOW ACCUMULATIONS EAST OF THE BLUE RIDGE ARE NOT EXPECTED. FRONTAL PASSAGE BEFORE DAWN WILL BE FOLLOWED BY MOISTURE WRAPPING AROUND A DEEPENING SURFACE LOW OVER THE INTERSTATE 77 CORRIDOR OF NC. PRECIPITATION MAY LINGER IN THE WESTERN NC PIEDMONT FOR A FEW HOURS AFTER DAYBREAK BEFORE THE SURFACE LOW MOVES OFF TO THE NE AND TAKES THE MOISTURE WITH IT. A TRANSITION FROM SNOW TO RAIN IS EXPECTED DURING THIS TIME FRAME. GUSTY NW WINDS BEHIND THE FRONT MAY SUPPORT A WIND ADVISORY NEAR THE BLUE RIDGE ON SATURDAY. MOIST NW FLOW SNOW WILL SET UP BEHIND THE FRONT...WITH SNOW CONTINUING IN THE NC MOUNTAINS UNTIL DRYING AT MIDDAY. MOST ACCUMULATIONS WILL BE ABOVE 3500 FEET...WHERE WINTER WEATHER ADVISORY CRITERIA ARE EXPECTED TO BE MET. A FEW LOCATIONS NEAR THE TN BORDER COULD RECEIVE FOUR TO FIVE INCHES...BUT THE COVERAGE WOULD BE TOO CONFINED TO ISSUE A WARNING FOR THOSE COUNTIES. HIGH TEMPERATURES SATURDAY WILL RUN SLIGHTLY BELOW NORMAL IN THE LEE OF THE MOUNTAINS AS COLD ADVECTION OFFSETS DOWNSLOPE FLOW WARMING. TEMPERATURES IN THE MOUNTAINS WOULD RUN ALMOST 12 DEGREES BELOW NORMAL IN COLD ADVECTION. && .SHORT TERM /TONIGHT THROUGH MONDAY/... AS OF 2 PM FRIDAY...WE BEGIN A WELL-DESERVED PERIOD OF RELATIVELY QUIET WEATHER. ONE LAST SHORT WAVE IS EXPECTED TO DROP DOWN INTO THE MEAN UPPER TROF OVER THE EAST ON SATURDAY NIGHT...AND IT WILL PASS EARLY ON SUNDAY MORNING. THIS WAVE WILL BRING SOME MOISTURE DOWN FROM THE NORTHWEST ON SUNDAY MORNING. THE LOW LEVEL FLOW AHEAD OF THE WAVE WILL BE WESTERLY...SO ALTHOUGH WE WILL HAVE SOME MID LEVEL FORCING WITH THE PASSAGE OF THE WAVE...THE LOW LEVELS WILL NOT BE COOPERATIVE FOR PRECIP PRODUCTION ON THE TN BORDER. WE ARE CARRYING A SLIGHT CHANCE POP OVER THE NORTHERN MTNS AND IT APPEARS THIS SHOULD SUFFICE...FOR SNOW SHOWERS MAINLY SUNDAY MORNING. ONCE THAT WAVE PASSES...THE UPPER PATTERN DEAMPLIFIES AND BEGINS A PERIOD OF NEARLY ZONAL FLOW INTO MONDAY AND BEYOND. A SHORT WAVE MOVING UP THE OH VALLEY ON MONDAY WILL DRAW MOISTURE FROM THE GULF WITH A DEVELOPING SOUTHERLY UPSLOPE COMPONENT. THIS COULD FORCE SOME SHOWER ACTIVITY OVER THE MTNS AND JUST E OF THE BLUE RIDGE IN THE AFTERNOON AS THE MOISTURE INCREASES. OTHERWISE...WE ARE LOOKING AT TEMPS SLOWLY MODERATING...WITH A RETURN TO NORMAL ON SUNDAY AND SUNDAY NIGHT...AND THEN SLIGHTLY ABOVE NORMAL ON MONDAY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 210 PM EST FRIDAY...ZONAL FLOW ACROSS THE CONUS WILL GIVE WAY TO AN RNA PATTERN LATER IN THE MEDIUM RANGE AS A TROUGH DIGS ACROSS THE WRN US...INDUCING RIDGING OVER THE EAST. MONDAY NIGHT A FAST MOVING SOUTHERN STREAM SHORT WAVE WILL CROSS THE REGION. BASED ON THE LLVL TEMPERATURE PROFILE...PCPN WITH THIS FEATURE SHOULD BE ALL RAIN. WITH THE BEST OF THE FORCING EXPECTED TO PASS NORTH OF THE REGION...QPF SHOULD BE LIGHT WITH THE WAVE IN ANY EVENT. TEMPERATURES WILL WARM CONSIDERABLY ON TUESDAY WITH MAX TEMPS EXPECTED TO RUN ABOUT 10 DEGREES ABOVE NORMAL ACROSS THE REGION. ON WEDNESDAY THE LONG WAVE RIDGE WILL BEGIN TO BUILD ACROSS THE SOUTHEAST STATES...YIELDING AN EVEN WARMER DAY. ONE POTENTIAL CAVEAT IS THAT THE GFS SHOWS QUITE A BIT OF LLVL MOISTURE. AS WARM ADVECTION INCREASES...AND THE COLD AIRMASS IS GRADUALLY DISPLACED BY MUCH WARMER AIR...WE COULD SEE QUITE A BIT OF STRATUS TUESDAY AND WEDNESDAY MORNINGS. THERE MAY BE SOME LIGHT SHOWER ACTIVITY OVER AND NEAR THE BLUE RIDGE BY EARLY WEDNESDAY MORNING AS PW/S INCREASE TO 150-175 PERCENT OF NORMAL ON THE GFS. SOUTHWESTERLY FLOW WILL BECOME STRONGER ON THURSDAY AS THE RIDGE BUILDS AND A SHORT WAVE LIFTS ACROSS THE UPPER MID-WEST. THE RESULTING INCREASE IN MOISTURE AND UPSLOPE FLOW MAY TRIGGER SHOWER ACTIVITY OVER THE REGION...ESPECIALLY ACROSS THE MOUNTAINS AND FOOTHILLS. THIS SEAMS REASONABLE AND WE HAVE SHOWERS OVER ALL BUT THE SOUTHEAST TIER OF COUNTIES FOR THURSDAY. THE LOW LIFTING ACROSS THE GREAT LAKES MAY PUSH A COLD FRONT INTO THE REGION BY FRIDAY. WE WILL SEE JUST HOW FAR THAT BOUNDARY WILL PUSH UNDER SOUTHWESTERLY FLOW ALOFT. THE ECMWF CAPE VALUES INCREASE TO OVER 1000 J/KG OVER THE FOOTHILLS AND PIEDMONT. THE GFS DEWPOINTS RISE INTO THE 60S...ALSO SUPPORTIVE OF DEEP CONVECTION. THEREFORE I HAVE SHOWERS AND THUNDERSTORMS IN FOR FRIDAY. IT/S WAY TOO EARLY TO ASCERTAIN THE SEVERE THREAT...THOUGH THE ANAFRONT NATURE OF THE SYSTEM WOULD BE MORE SUPPORTIVE OF HEAVY RAIN OUT AT DAY 7 AND BEYOND. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AT KCLT...THE LEADING EDGE OF STEADIER RAIN IS MAKING STEADY EASTWARD PROGRESS ACRS THE UPSTATE ATTM...WITH THE BEST PERIOD OF LIFT AND MOISTURE EXPECTED TO AFFECT THE TERMINAL BETWEEN 07-11Z. DURING THIS TIME...TEMPORARY RESTRICTIONS TO MVFR DUE TO RAIN AND/OR CIGS ARE EXPECTED. TOWARD THE START OF THE MORNING PUSH TIME...WINDS SHOULD HAVE VEERING TO WSW WITH A SWITCH TO WNW OR NW SHORTLY THEREAFTER. IN THE IMMEDIATE WAKE OF THE EARLY MORNING WAVE PASSAGE...CAA AND SFC PRESSURE RISES SHOULD CAUSE THE WESTERLY WIND TO BECOMING GUSTY AND REMAIN THAT WAY FOR MUCH OF THE DAY. A QUICK IMPROVEMENT TO VFR SHOULD OCCUR NOT TOO FAR AFTER DAYBREAK. ELSEWHERE...AHEAD OF A FAST MOVING S/WV TROUGH...A PERIOD OF RAIN AND MTN SNOW...ALONG WITH MVFR CIGS IS EXPECTED DURING THE PRE-DAWN HOURS. WINDS WILL VEER TO WESTERLY AND BECOME GUSTY DURING THE EARLY TO MID-MORNING HOURS AS PCPN CHANCES END EAST OF THE BLUE RIDGE. CIG RESTRICTIONS AND SNOW SHOWER CHANCES WILL BECOMING INCREASINGLY CONFINED TO THE TENNESSEE BORDER COUNTIES AS THE MORNING WEARS ON BEFORE ENDING ALTOGETHER THIS AFTERNOON. OUTLOOK...VFR BUT BREEZY CONDITIONS ARE TONIGHT AND THRU THE WEEKEND. PRECIP OR LOW CIGS MAY RETURN WITH A FRONTAL PASSAGE MONDAY NIGHT. THE SOUTHEAST U.S. SHOULD SEE A SPRINGLIKE WARM AND WET PATTERN LATER IN THE WEEK...WITH SHRA/TSRA CAUSING SPOTTY RESTRICTIONS. CONFIDENCE TABLE... 05-11Z 11-17Z 17-23Z 23-05Z KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 95% KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 92% KAVL HIGH 100% HIGH 100% HIGH 100% HIGH 84% KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 82% KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 92% KAND HIGH 100% HIGH 100% HIGH 100% HIGH 92% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...WIND ADVISORY FROM 6 AM THIS MORNING TO 6 PM EST THIS EVENING FOR NCZ033-049-050-052-053-064-065-501-503-505-507-509. WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NCZ033-048>052-058-059-062-063. SC...WIND ADVISORY FROM 6 AM THIS MORNING TO 6 PM EST THIS EVENING FOR SCZ003. && $$ SYNOPSIS...JAT NEAR TERM...JAT/WIMBERLEY SHORT TERM...PM LONG TERM...MCAVOY AVIATION...CSH/WIMBERLEY
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
904 PM MST SUN FEB 16 2014 .UPDATE... ISSUED AT 900 PM MST SUN FEB 16 2014 LATEST RADAR/SATELLITE LOOPS SHOW BACK EDGE OF PRECIP SHIELD OVER FAST WESTERN SD...MOVING EAST WITH MAIN BAND OF SHRASN PUSHING INTO CENTRAL SD. HAVE ADJUSTED POPS/WEATHER TO ACCOUNT FOR SLIGHTLY SLOWER TIMING THAN PREVIOUS THOUGHT. HIGH WIND WARNING ALLOWED TO EXPIRE AS BOUNDARY LAYER SLOWLY DECOUPLES AND SQUEEZE AROUND THE BLACK HILLS TAPERS OFF. UPDATE ISSUED AT 448 PM MST SUN FEB 16 2014 21Z RAP SUPPORTS A STRONG ISALLOBARIC PUSH ASSOCIATED WITH FAST MOVING COLD FRONT AND 50KT BOUNDARY LAYER WINDS. SPEARFISH JUST GUSTED TO 56KTS WITH PASSAGE...SO WILL THROW OUT A SHORT HIGH WIND WARNING FOR THE LEE SIDE OF THE BLACK HILLS. && .SHORT TERM...THIS EVENING THROUGH MONDAY NIGHT ISSUED AT 300 PM MST SUN FEB 16 2014 CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER SOUTHWEST SK...WITH SECONDARY LOW OVER SOUTHEASTERN MT. ARCTIC BOUNDARY STRETCHES FROM NORTHEASTERN MT INTO CENTRAL SD. PACIFIC COLD FRONT IS NOW MOVING QUICKLY EAST ACROSS EASTERN MT AND INTO NORTHEASTERN WY. UPPER LEVEL ANALYSIS SHOWS WEAK RIDGING OVER THE HIGH PLAINS...WITH A TROF BEHIND IT MOVING ACROSS THE ROCKIES AND INTO THE HIGH PLAINS. STRONG SYSTEM STILL CONTINUES TO SIT AND SPIN OFF THE PACIFIC NW COAST. SKIES ARE MOSTLY CLOUDY ACROSS MUCH OF THE AREA...WITH SOME BREAKS OF SUN...ESPECIALLY ACROSS SOUTHERN AREAS. A WIDE RANGE OF TEMPS ARE IN PLACE ACROSS THE CWA RIGHT NOW...20S AND LOWER 30S OVER FAR NORTHWESTERN SD...TO THE 50S OVER SOUTHWESTERN SD. WINDS ARE SOUTH TO SOUTHEAST TO THE NORTH AND EAST OF THE BLACK HILLS...WITH WEST TO SOUTHWEST WINDS OVER NORTHEASTERN WY AND THE BLACK HILLS. UPPER LEVEL SHORTWAVE WILL MOVE QUICKLY ACROSS THE REGION LATE TODAY AND TONIGHT...EXITING OUR AREA OVERNIGHT. THE BULK OF SHOWER ACTIVITY WILL BE BETWEEN 00Z AND 06Z...WITH THE BEST CHANCES ACROSS NORTHEASTERN WY...THE BLACK HILLS...AND SOUTHWESTERN SD...AS SHOWERS ALONG THE FRONT MOVE EAST-SOUTHEAST. HAVE RAISED POPS A BIT MORE ACROSS THESE AREAS. A LIGHTNING STRIKE OR TWO CANNOT BE RULED OUT ACROSS NORTHEASTERN WY LATE THIS AFTERNOON. COLD FRONT WILL ACCOMPANY THE WAVE AND BRING A QUICK AND SHARP COOLDOWN BEHIND IT LATE THIS AFTERNOON AND EVENING. PCPN WILL MAINLY START OFF AS RAIN...BUT SHOULD QUICKLY CHANGEOVER TO SNOW...ESPECIALLY ACROSS NORTHEASTERN WY AND THE BLACK HILLS...AS LOWER ATMOSPHERE SATURATES AND WET BULB ZERO HEIGHTS DROP. SOME HEAVIER SHOWERS LOOK LIKELY OVER NORTHEASTERN WY AND SOUTHWESTERN SD...SO THINKING SOME ACCUMULATION IS LIKELY IN THESE AREAS...PROBABLY 1 TO 2 INCHES WHERE THESE HEAVIER SHOWERS PASS ACROSS. THERE IS ALSO POTENTIAL FOR STRONG WIND GUSTS IN THE VICINITY OF SHOWERS AND BRIEFLY AS THE FRONT PASSES...AS 30 TO 50 KT LOW LEVEL JET PASSES ACROSS THE REGION. BULK OF SHOWERS WILL MOVE SOUTH OF THE AREA AND DISSIPATE BY MIDNIGHT...WITH JUST A SLIGHT CHANCE THEREAFTER OVER SOUTH CENTRAL SD. LOWS WILL BE IN THE 20S. NORTHWESTERLY FLOW ALOFT WILL CONTINUE TO BRING DISTURBANCES ACROSS THE REGION THIS WEEK...THOUGH THE DISTURBANCES EARLY IN THE WEEK WILL BE VERY WEAK AND JUST BRING SOME MID AND HIGH CLOUDS. SKIES WILL BE MOSTLY SUNNY ON MONDAY WITH ABOVE AVERAGE TEMPERATURES PERSISTING. HIGHS WILL BE IN THE 40S AND 50S...WARMEST ACROSS SOUTHERN SD. GUSTY SOUTHWESTERLY WINDS CAN BE EXPECTED ACROSS NORTHEASTERN WY...ESPECIALLY CAMPBELL CO. SOME CLOUDS CAN BE EXPECTED MONDAY NIGHT...ESPECIALLY ACROSS WESTERN PORTIONS OF THE CWA...WITH LOWS IN THE MID 20S TO MID 30S. && .LONG TERM...TUESDAY THROUGH SUNDAY ISSUED AT 300 PM MST SUN FEB 16 2014 SEMI-AMPLIFIED WESTERLY FLOW WILL PERSIST THROUGH THE MIDDLE OF THE WEEK BEFORE AN UPPER FLOW PATTERN CHANGE ENSUES. UPPER JET AND ASSOCIATED IMPULSES EMANATING FROM THE NE PAC UPPER TROUGH WILL CONTINUE TO BRING NEAR DAILY DISTURBANCES THROUGH THE NORTHERN PLAINS...WITH ASSOCIATED SFC COLD FRONTS AND WINDY CONDITIONS EARLY IN THE PERIOD. THE RETURN OF THE EASTERN PAC/WESTERN CONUS RIDGE TOWARD THE END OF THE WEEK IS EXPECTED...AS A STRONG MID TROPOSPHERIC JET ADVECTS EAST OUT OF ASIA AND SUPPORTS BREAKDOWN OF THE NE PAC UPPER TROUGH...WITH TENDENCIES TOWARD A POTENTIALLY STRONG POSITIVE PNA. THE RESULT OF THIS TRANSITION WILL BE THE RETURN OF COLD AIR TO THE REGION WITH FAIRLY LONG TRAJECTORY NORTHERLY FLOW ALOFT. ECMWF AND NAEFS GUIDANCE BEYOND NEXT WEEKEND ARE LEANING TOWARD ONLY A BRIEF STAY /3-4 DAYS/ OF COLD CONDITIONS...WITH AN EASTERN SHIFT OF THE WESTERN NOAM RIDGE BY EARLY NEXT WEEK. HIGHS WILL GENERALLY BE IN THE 40S AND 50S THROUGH MID WEEK...WITH A RETURN OF NORMAL TO BELOW NORMAL TEMPS BY FRIDAY. CARRIED PERIODIC POPS IN THE WED THROUGH SAT PERIOD...WITH MEAN UPPER LEVEL TROUGHING AND THE POTENTIAL FOR NORTHERLY FLOW IMPULSES ROTATING AROUND THE EDGE OF THE HUDSON BAY LOW BY THE WEEKEND. WED/S SYSTEM HAS TRENDED STRONGER AND EARLIER AND HAVE SHIFTED POPS EAST SOME. OTHERWISE...STILL MUCH UNCERTAINTY WRT TO IMPULSE TIMING/TRACK WHICH WILL DICTATE PRECIP CHANCES BEYOND THUR. HENCE...RETAINED PREVIOUS LOW POP MENTIONS FRI AND SAT. NO SIG WX SYSTEMS OR SNOW ACCUMS EXPECTED ATTM. AS STATED ABOVE...DEGREE OF CAA WILL HINGE ON HOW FAST THE WESTERN CONUS RIDGE SHIFTS EAST...WITH THE MAJORITY OF HEIGHT FALLS AND CAA STILL PROGGED TO REMAIN ENE OF THE FA. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 900 PM MST SUN FEB 16 2014 BAND OF MVFR CIGS/VSBYS...LOCAL IFR CONDITIONS...DUE TO SHRASN ACROSS THE SD PLAINS WILL QUICKLY EXIT THE CWA OVERNIGHT LEADING TO VFR CONDITIONS FOR MONDAY. GUSTY NORTHWEST WINDS ON THE SD PLAINS WILL SLOWLY SUBSIDE FROM WEST TO EAST OVERNIGHT. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ UPDATE...HELGESON SHORT TERM...26 LONG TERM...JC AVIATION...HELGESON
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
451 PM MST SUN FEB 16 2014 .UPDATE... ISSUED AT 448 PM MST SUN FEB 16 2014 21Z RAP SUPPORTS A STRONG ISALLOBARIC PUSH ASSOCIATED WITH FAST MOVING COLD FRONT AND 50KT BOUNDARY LAYER WINDS. SPEARFISH JUST GUSTED TO 56KTS WITH PASSAGE...SO WILL THROW OUT A SHORT HIGH WIND WARNING FOR THE LEE SIDE OF THE BLACK HILLS. && .SHORT TERM...THIS EVENING THROUGH MONDAY NIGHT ISSUED AT 300 PM MST SUN FEB 16 2014 CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER SOUTHWEST SK...WITH SECONDARY LOW OVER SOUTHEASTERN MT. ARCTIC BOUNDARY STRETCHES FROM NORTHEASTERN MT INTO CENTRAL SD. PACIFIC COLD FRONT IS NOW MOVING QUICKLY EAST ACROSS EASTERN MT AND INTO NORTHEASTERN WY. UPPER LEVEL ANALYSIS SHOWS WEAK RIDGING OVER THE HIGH PLAINS...WITH A TROF BEHIND IT MOVING ACROSS THE ROCKIES AND INTO THE HIGH PLAINS. STRONG SYSTEM STILL CONTINUES TO SIT AND SPIN OFF THE PACIFIC NW COAST. SKIES ARE MOSTLY CLOUDY ACROSS MUCH OF THE AREA...WITH SOME BREAKS OF SUN...ESPECIALLY ACROSS SOUTHERN AREAS. A WIDE RANGE OF TEMPS ARE IN PLACE ACROSS THE CWA RIGHT NOW...20S AND LOWER 30S OVER FAR NORTHWESTERN SD...TO THE 50S OVER SOUTHWESTERN SD. WINDS ARE SOUTH TO SOUTHEAST TO THE NORTH AND EAST OF THE BLACK HILLS...WITH WEST TO SOUTHWEST WINDS OVER NORTHEASTERN WY AND THE BLACK HILLS. UPPER LEVEL SHORTWAVE WILL MOVE QUICKLY ACROSS THE REGION LATE TODAY AND TONIGHT...EXITING OUR AREA OVERNIGHT. THE BULK OF SHOWER ACTIVITY WILL BE BETWEEN 00Z AND 06Z...WITH THE BEST CHANCES ACROSS NORTHEASTERN WY...THE BLACK HILLS...AND SOUTHWESTERN SD...AS SHOWERS ALONG THE FRONT MOVE EAST-SOUTHEAST. HAVE RAISED POPS A BIT MORE ACROSS THESE AREAS. A LIGHTNING STRIKE OR TWO CANNOT BE RULED OUT ACROSS NORTHEASTERN WY LATE THIS AFTERNOON. COLD FRONT WILL ACCOMPANY THE WAVE AND BRING A QUICK AND SHARP COOLDOWN BEHIND IT LATE THIS AFTERNOON AND EVENING. PCPN WILL MAINLY START OFF AS RAIN...BUT SHOULD QUICKLY CHANGEOVER TO SNOW...ESPECIALLY ACROSS NORTHEASTERN WY AND THE BLACK HILLS...AS LOWER ATMOSPHERE SATURATES AND WET BULB ZERO HEIGHTS DROP. SOME HEAVIER SHOWERS LOOK LIKELY OVER NORTHEASTERN WY AND SOUTHWESTERN SD...SO THINKING SOME ACCUMULATION IS LIKELY IN THESE AREAS...PROBABLY 1 TO 2 INCHES WHERE THESE HEAVIER SHOWERS PASS ACROSS. THERE IS ALSO POTENTIAL FOR STRONG WIND GUSTS IN THE VICINITY OF SHOWERS AND BRIEFLY AS THE FRONT PASSES...AS 30 TO 50 KT LOW LEVEL JET PASSES ACROSS THE REGION. BULK OF SHOWERS WILL MOVE SOUTH OF THE AREA AND DISSIPATE BY MIDNIGHT...WITH JUST A SLIGHT CHANCE THEREAFTER OVER SOUTH CENTRAL SD. LOWS WILL BE IN THE 20S. NORTHWESTERLY FLOW ALOFT WILL CONTINUE TO BRING DISTURBANCES ACROSS THE REGION THIS WEEK...THOUGH THE DISTURBANCES EARLY IN THE WEEK WILL BE VERY WEAK AND JUST BRING SOME MID AND HIGH CLOUDS. SKIES WILL BE MOSTLY SUNNY ON MONDAY WITH ABOVE AVERAGE TEMPERATURES PERSISTING. HIGHS WILL BE IN THE 40S AND 50S...WARMEST ACROSS SOUTHERN SD. GUSTY SOUTHWESTERLY WINDS CAN BE EXPECTED ACROSS NORTHEASTERN WY...ESPECIALLY CAMPBELL CO. SOME CLOUDS CAN BE EXPECTED MONDAY NIGHT...ESPECIALLY ACROSS WESTERN PORTIONS OF THE CWA...WITH LOWS IN THE MID 20S TO MID 30S. && .LONG TERM...TUESDAY THROUGH SUNDAY ISSUED AT 300 PM MST SUN FEB 16 2014 SEMI-AMPLIFIED WESTERLY FLOW WILL PERSIST THROUGH THE MIDDLE OF THE WEEK BEFORE AN UPPER FLOW PATTERN CHANGE ENSUES. UPPER JET AND ASSOCIATED IMPULSES EMANATING FROM THE NE PAC UPPER TROUGH WILL CONTINUE TO BRING NEAR DAILY DISTURBANCES THROUGH THE NORTHERN PLAINS...WITH ASSOCIATED SFC COLD FRONTS AND WINDY CONDITIONS EARLY IN THE PERIOD. THE RETURN OF THE EASTERN PAC/WESTERN CONUS RIDGE TOWARD THE END OF THE WEEK IS EXPECTED...AS A STRONG MID TROPOSPHERIC JET ADVECTS EAST OUT OF ASIA AND SUPPORTS BREAKDOWN OF THE NE PAC UPPER TROUGH...WITH TENDENCIES TOWARD A POTENTIALLY STRONG POSITIVE PNA. THE RESULT OF THIS TRANSITION WILL BE THE RETURN OF COLD AIR TO THE REGION WITH FAIRLY LONG TRAJECTORY NORTHERLY FLOW ALOFT. ECMWF AND NAEFS GUIDANCE BEYOND NEXT WEEKEND ARE LEANING TOWARD ONLY A BRIEF STAY /3-4 DAYS/ OF COLD CONDITIONS...WITH AN EASTERN SHIFT OF THE WESTERN NOAM RIDGE BY EARLY NEXT WEEK. HIGHS WILL GENERALLY BE IN THE 40S AND 50S THROUGH MID WEEK...WITH A RETURN OF NORMAL TO BELOW NORMAL TEMPS BY FRIDAY. CARRIED PERIODIC POPS IN THE WED THROUGH SAT PERIOD...WITH MEAN UPPER LEVEL TROUGHING AND THE POTENTIAL FOR NORTHERLY FLOW IMPULSES ROTATING AROUND THE EDGE OF THE HUDSON BAY LOW BY THE WEEKEND. WED/S SYSTEM HAS TRENDED STRONGER AND EARLIER AND HAVE SHIFTED POPS EAST SOME. OTHERWISE...STILL MUCH UNCERTAINTY WRT TO IMPULSE TIMING/TRACK WHICH WILL DICTATE PRECIP CHANCES BEYOND THUR. HENCE...RETAINED PREVIOUS LOW POP MENTIONS FRI AND SAT. NO SIG WX SYSTEMS OR SNOW ACCUMS EXPECTED ATTM. AS STATED ABOVE...DEGREE OF CAA WILL HINGE ON HOW FAST THE WESTERN CONUS RIDGE SHIFTS EAST...WITH THE MAJORITY OF HEIGHT FALLS AND CAA STILL PROGGED TO REMAIN ENE OF THE FA. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 448 PM MST SUN FEB 16 2014 IFR ST/FG WILL CONTINUE OVER FAR NORTHEAST PORTIONS OF THE AREA THROUGH EARLY THIS EVENING. A FAST MOVING COLD FRONT WILL RACE THROUGH THE CWA TONIGHT BRINGING SHRASN CHANGING TO SHSN ALONG WITH GUSTY NORTHWEST WINDS WITH THE SHOWERS. GUSTS TO 55KTS WILL OCCUR ALONG THE LEE SIDE OF THE BLACK HILLS AS THE FRONT SURGES SOUTHEAST. MVFR CIGS/VSBYS WILL BE ASSOCIATED WITH THE SHOWERS. CONDITIONS WILL RAPIDLY IMPROVE AFTER 06Z TONIGHT AS DRIER AIR MOVES INTO THE REGION. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...HIGH WIND WARNING UNTIL 9 PM MST THIS EVENING FOR SDZ012-025-026- 031-072-073. WY...NONE. && $$ UPDATE...HELGESON SHORT TERM...26 LONG TERM...JC AVIATION...HELGESON
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
420 AM EST SAT FEB 15 2014 .SHORT TERM...(TODAY AND TONIGHT)...(TODAY AND TONIGHT)...LOW PRESSURE OVER WRN NC AND CENTRAL VA CONTINUES TO MOVE EAST TO NORTHEAST THIS MORNING. THE ASSOCIATED COLD FRONT HAD JUST MOVED EAST OFF THE CUMBERLAND PLATEAU AT 09Z. TEMPS STAYED ON THE MILD SIDE OVERNIGHT AND HAD JUST RECENTLY FALLEN BELOW 32 DEGREES ACROSS OUR NRN PLATEAU COUNTIES AND PARTS OF LEE AND WISE COUNTIES OF SW VA. WRAP AROUND MOISTURE WILL CONTINUE TO AFFECT MAINLY SW VA AND NE TN THIS MORNING...BUT WAS ALREADY BECOMING VERY SHALLOW OVER WRN AREAS. THE MOISTURE DECREASE AND MILD TEMPS OVERNIGHT SEVERELY HINDERED GETTING MUCH SNOW ACCUMULATIONS ON OUR PLATEAU AND CENTRAL VALLEY COUNTIES...SO OPTED TO CANCEL THE WINTER WEATHER ADVISORY FOR THOSE AREAS. KEEPING THE ADVISORY AND WARNING AREAS INTACT FOR NOW FOR SW VA...NE TN AND THE NRN/SMOKY MTNS OF E TN. RUC AND NAM MODELS SHOW A DECENT AMOUNT OF W-NW UPSLOPE LOW LEVEL FLOW AND SOME INSTABILITY THROUGH THE MORNING HOURS...PLUS SOUNDINGS IN THESE AREAS INDICATED A GOOD POSSIBILITY OF SNOW OCCURRING ABOVE 2500 TO 3000 FEET OVERNIGHT. OTHERWISE...TEMPS WILL PROBABLY MAX OUT THIS MORNING OR AT BEST WARM A FEW DEGREES IN THE AFTERNOON WITH SUNSHINE EXPECTED. MID AND HIGH CLOUDS SHOULD INCREASE TONIGHT WHICH SUPPORTED MORE OF A BLEND OF THE DIFFERING MOS MINS. ANY PRECIPITATION FOR TONIGHT APPEARS TO BE A TRACE EVENT WITH FLURRIES...WHICH WAS DOWNPLAYED IN THE GRIDS. LATER SHIFTS MAY BE ABLE TO DROP ALL MENTION OF ANY FLURRIES FOR TONIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY)...WEAK DISTURBANCE IN NW FLOW WILL BRUSH NE TN AND SW VA SUNDAY MORNING. SOME LIGHT SNOW OR SNOW FLURRIES WILL END BY LATE MORNING THEN WEAK HIGH PRESSURE WILL BUILD ACROSS THE FORECAST AREA WITH FLOW BECOMING MORE ZONAL. SKIES WILL BECOME MOSTLY SUNNY CENTRAL AND SOUTH WITH TEMPERATURES WARMING TO NEAR AVERAGE ACROSS THE SOUTH AND CENTRAL BUT LINGERING CLOUDS ACROSS THE NORTH WILL KEEP HIGHS THERE IN THE UPPER 30S TO LOWER 40S. SUNDAY NIGHT HIGH PRESSURE BEGINS TO SHIFT EAST. MONDAY LOW PRESSURE OVER THE SOUTHERN PLAINS AND DEVELOPING FRONTAL SYSTEM SPREADS CLOUDS INTO THE TN VALLEY WITH CHANCE OF RAIN BY AFTERNOON. SOUTH TO SOUTHWEST WINDS AHEAD OF THE FRONT WILL WARM TEMPERATURES INTO THE 50S. THIS IS THE BEGINNING OF A MUCH WARMER PATTERN. AS THE FRONT MOVES THROUGH MONDAY NIGHT SKIES WILL CLEAR EARLY TUESDAY AS HIGH PRESSURE SHIFTS EAST. TUESDAY WILL CONTINUE TO BE MILDER AND SUNNY WITH HIGHS IN THE 50S TO LOWER 60S. TUESDAY NIGHT MOISTURE SPREADS BACK NORTH AND AN UNSETTLED PATTERN SETS UP WITH SHOWERS WEDNESDAY AS A DEEPER AREA OF LOW PRESSURE FORMS OVER THE PLAINS BY WEDNESDAY NIGHT. THIS STRONGER SYSTEM BRINGS EVEN WARMER CONDITIONS WEDNESDAY AND THURSDAY AS THE MAIN FRONTAL SYSTEM APPROACHES. SHOWERS AGAIN WILL BE ON THE INCREASE WITH THE AIR MASS BECOMING UNSTABLE THURSDAY INTO FRIDAY WITH THUNDERSTORMS POSSIBLE AS HIGHS REACH INTO THE 60S IN ALL BUT THE HIGHER ELEVATIONS BOTH DAYS. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 38 29 53 32 58 / 10 10 10 10 30 KNOXVILLE MCGHEE TYSON AIRPORT, TN 38 28 49 30 55 / 20 20 10 10 30 OAK RIDGE, TN 36 27 50 30 54 / 20 20 10 10 30 TRI CITIES AIRPORT, TN 35 22 42 24 49 / 50 20 20 10 20 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR THE FOLLOWING ZONES: HANCOCK...HAWKINS...NORTHWEST CARTER... NORTHWEST GREENE...SULLIVAN...WASHINGTON TN. WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR THE FOLLOWING ZONES: BLOUNT SMOKY MOUNTAINS...COCKE SMOKY MOUNTAINS...JOHNSON...SEVIER SMOKY MOUNTAINS...SOUTHEAST CARTER...SOUTHEAST GREENE...SOUTHEAST MONROE...UNICOI. VA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR THE FOLLOWING ZONES: LEE...RUSSELL...SCOTT...WASHINGTON. WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR THE FOLLOWING ZONES: WISE. && $$ TG/TD
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AREA FORECAST DISCUSSION
NWS LA CROSSE WI
510 PM CST SUN FEB 16 2014 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 316 PM CST SUN FEB 16 2014 MAIN SHORT TERM FORECAST IS ON HEAVY SNOW EXPECTED MONDAY MORNING. CURRENTLY AS OF 20Z...WATER VAPOR IMAGERY AND RAP 500MB HEIGHT ANALYSIS SHOWED A SHORTWAVE TROUGH EXTENDING FROM ALBERTA THROUGH IDAHO...RIDGING FROM TEXAS INTO SOUTHERN MANITOBA...AND TROUGHING OVER THE NORTHEAST U.S.. WITH THE FORECAST AREA IN THE INFLECTION POINT EAST OF THE UPPER RIDGE AXIS...HIGH PRESSURE EXISTS AT THE SURFACE WITH SUBSIDENCE AND DRYING IN THE LOW TO MID LEVELS. THIS RESULTED IN CLEARING OF LOW CLOUDS THIS MORNING. HOWEVER...MID AND HIGH CLOUDS ARE QUICKLY SPREADING EAST FROM THE DAKOTAS INTO THE FORECAST AREA. THESE ARE ASSOCIATED WITH A WARM ADVECTION REGIME IN PLACE ON THE BACK SIDE OF THE SURFACE HIGH. PRECIPITABLE WATER ANALYSIS SHOWED VALUES AROUND 0.5 INCH FROM OKLAHOMA INTO WESTERN NORTH DAKOTA...COMPARED TO 0.1-0.25 INCHES OVER THE FORECAST AREA. MODELS REMAIN CONSISTENT WITH THE EXPECTED SNOW TO MOVE ACROSS THE AREA LATER TONIGHT INTO MONDAY. THE MAIN FEATURE RESPONSIBLE FOR THE SNOW IS THE SHORTWAVE TROUGH OVER IDAHO WHICH REACHES THE FORECAST AREA AT 18Z MONDAY. ITS WORTH NOTING THAT BETWEEN 12-18Z MONDAY THE SHORTWAVE TROUGH INTENSIFIES AND TAKES ON A NEGATIVE TILT. IN RESPONSE LIFT GREATLY INCREASES AHEAD OF THE TROUGH...AND TO BALANCE SUBSIDENCE INCREASES BEHIND IT. THE LIFT WILL ACT ON THE PLUME OF 0.5 INCH PRECIPITABLE WATER SEEN OVER THE WESTERN DAKOTAS TO PRODUCE THE SNOW. SOME INTERESTING FACETS FOR TONIGHT INTO MONDAY... 1. AS THE LOW LEVEL JET INCREASES TONIGHT AHEAD OF THE TROUGH...IT APPEARS A WARM ADVECTION BAND OF SNOW WILL DEVELOP FROM CENTRAL INTO SOUTHEAST MN AROUND MIDNIGHT...THEN LIFT NORTHEASTWARD THROUGH THE REST OF THE NIGHT. UNSURE HOW MUCH OF THIS SNOW WILL REACH THE SURFACE AS MODELS DEPICT LEFTOVER DRY AIR BETWEEN 750-900MB THAT NEEDS SATURATING. THEREFORE...PRECIPITATION CHANCES ARE KEPT LOWER PRIOR TO 09Z. AS WE APPROACH 12Z...THE BIG BATCH OF SNOW ASSOCIATED WITH THE WARM CONVEYOR BELT AND DPVA AHEAD OF THE SHORTWAVE TROUGH WILL ENCOMPASS MUCH OF THE WESTERN HALF OF THE FORECAST AREA. 2. THERE IS A VERY TIGHT MODEL CONSENSUS FOR 12-18Z MONDAY TO BE THE TIME PERIOD OF HEAVIEST QPF/SNOW. WITH A LITTLE NEGATIVE EPV THROWN IN IN THE MID LEVELS...EASILY COULD SEE SOME CONVECTIVE NATURE TO THE SNOW. SNOWFALL RATES OF 1 INCH PER HOUR EASILY SEEM PLAUSIBLE FOR A COUPLE HOURS...KNOCKING VISIBILITIES DOWN TO 1/4 MILE. THESE RATES SHOULD OCCUR AT THE WORST TIME...MORNING COMMUTE. ALTHOUGH TOTAL SNOWFALL AMOUNTS OVER THE SOUTHWEST HALF OF THE FORECAST AREA ARE ONLY FORECAST RIGHT NOW IN THE 4-5 INCH RANGE...BELOW WARNING CRITERIA...ISSUED A WARNING BASED ON TIME OF DAY. FAR WESTERN AREAS SUCH AS ROCHESTER LOOK TO GET INTO SOME BLOWING SNOW TOO. ALSO WARNED FOR THAT AREA BECAUSE THE 16.12Z MODELS HAVE TRENDED QPF UP ACROSS THE SOUTHERN PORTION OF THE FORECAST AREA...NOW NEAR 1/3 OF AN INCH. 3. WITH THE STRONG SUBSIDENCE OCCURRING ON THE BACK SIDE OF THE TROUGH...SKIES SHOULD CLEAR WEST TO EAST DURING THE MID AFTERNOON INTO THE EVENING HOURS. THIS SHOULD MAKE THE AFTERNOON COMMUTE MUCH MORE MANAGEABLE...PROVIDED ROADS ARE CLEANED UP IN TIME. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 316 PM CST SUN FEB 16 2014 AFTER AN ACTIVE SHORT TERM PERIOD...THE LONG TERM LOOKS FAIRLY QUIET. THERE ARE SOME ITEMS OF INTEREST... 1. TEMPERATURES CLIMBING ABOVE NORMAL TUESDAY AND WEDNESDAY. THE FLOW PATTERN BECOMES MORE ZONAL...ALLOWING PACIFIC AIR TO FLOW INTO THE FORECAST AREA. WARMEST DAY SHOULD COME TUESDAY AHEAD OF A COLD FRONT PASSING THROUGH LATE IN THE DAY. 850MB TEMPS ARE PROGGED TO CLIMB TO 4-6C...WHICH SHOULD ALLOW HIGHS TO TOP OUT AS HIGH AS THE LOW 40S. SLIGHTLY COOLER CONDITIONS ARE FORECAST ON WEDNESDAY BEHIND THE FRONT. IT SHOULD BE NOTED THAT THE LAST TIME LA CROSSE WAS ABOVE NORMAL WAS JANUARY 30TH. AT ROCHESTER...IT WAS JANUARY 16TH. 2. STORM SYSTEM LIFTING OUT OF THE CENTRAL PLAINS WEDNESDAY NIGHT. ECMWF RUNS FROM 15.00Z AND PRIOR TOOK THIS SYSTEM AND REALLY INTENSIFIED IT WHILE LIFTING NORTHEAST THROUGH THE FORECAST AREA. THAT CHANGED WITH THE 15.12Z ECMWF AND LATEST 16.12Z ECMWF/CANADIAN/GFS CONTINUE TO BRING THE SYSTEM INTO LOWER MICHIGAN BY THURSDAY EVENING. ALONG ITS TRACK...ASSISTED BY A NORTHERN STREAM SHORTWAVE TROUGH CROSSING THE UPPER MIDWEST...A BAND OF PRECIPITATION IS LOOKING MORE LIKELY TO MOVE THROUGH THE AREA LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. ENOUGH WARM AIR LOOKS TO GET PULLED UP INTO THE SYSTEM TO ALLOW FOR A MIX OF PRECIPITATION IN SOUTHEAST SECTIONS OF THE FORECAST AREA. SOMETHING WORTH MONITORING. 3. SYSTEM TO BRING A BRIEF BOUT OF SNOW FRIDAY INTO FRIDAY NIGHT. BOTH THE 16.12Z GFS AND CANADIAN BRING A SHORTWAVE TROUGH AND DEFORMATION SNOW ACROSS THE FORECAST AREA DURING THIS TIME FRAME. HOWEVER...THERE IS NO SIGN OF THIS SHORTWAVE IN THE ECMWF. FOR NOW JUST HAVE LOW CHANCES OF SNOW IN THE FORECAST. 4. HEADING BACK TO BELOW NORMAL BEGINNING THURSDAY NIGHT. ALL MODELS HAVE MATCHED UP WELL WITH CFS FORECASTS SUGGESTING TEMPERATURES GOING BACK BELOW NORMAL AS TROUGHING REESTABLISHES ITSELF OVER THE UPPER MIDWEST. BY THE WEEKEND...850MB TEMPS MAY GET STUCK BELOW -10C AGAIN...WITH SOME HINTS OF -20C AIR COMING AT THE AREA JUST BEYOND THE LONG TERM PERIOD. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 510 PM CST SUN FEB 16 2014 WINTER STORM WILL BRING SNOW...LOW VSBYS/CLOUDS...AND GUSTY WINDS TO THE REGION MONDAY MORNING. INCH PER HOUR SNOWFALL RATES ARE EXPECTED FOR A FEW HOURS...AND BLSN SHOULD OCCUR AT KRST FOR A GOOD PORTION OF THE DAY. TIMING ON WHEN THE HEAVIEST SNOW MOVES IN...AND MOVES OUT...PRESENTS SOME CHALLENGES. BUFKIT SOUNDINGS SUGGEST A FEW HOURS EARLIER THAN MODELED QPF FIELDS. MEANWHILE...MID LEVEL FRONTOGENETIC WING COULD PRODUCE A BAND OF SNOW WELL AHEAD OF THE MAIN AREA SNOW. MOST OF THIS WOULD PROBABLY BE 4-P6SM FOR VSBY. OVERALL TRENDS THE PAST COUPLE DAYS HAS BEEN TO SLOW DOWN THE SYSTEM. WILL PUSH THE ONSET OF THE SUB 1SM SNOWS A COUPLE HOURS...STILL FOCUSING ON A 4-5 HOUR TIME FRAME FOR THE HEAVY SNOW. WINDS ARE GOING TO INCREASE THIS EVENING FROM THE SOUTHEAST AS THE PRESSURE GRADIENT TIGHTENS AHEAD OF THE SHORTWAVE TROUGH/SFC LOW. SOME SLACKENING CAN BE EXPECTED AS THE SNOW COMES IN - WITH A BAGGIER GRADIENT. STILL...IT WILL BE STRONG ENOUGH TO BLOW/DRIFT THE SNOW AT KRST...AND MUCH OF THE VSBY REDUCTIONS OUTSIDE OF THE HEAVY SNOW CAN BE ATTRIBUTED TO THAT. THE SYSTEM/S COLD FRONT SHOULD MOVE THROUGH IN THE 21-00Z MON TIME FRAME...WITH A SCATTERING OUT OF THE CLOUD DECK. ANTICIPATE REFINEMENTS TO THE FORECAST AS RADAR TRENDS MAKE SNOW ONSET/EXIT MORE EVIDENT. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...WINTER STORM WARNING FROM 3 AM TO 3 PM CST MONDAY FOR WIZ017-029- 032>034-041>044-053>055-061. MN...WINTER STORM WARNING FROM 3 AM TO 3 PM CST MONDAY FOR MNZ079- 086>088-094>096. IA...WINTER STORM WARNING FROM 3 AM TO 3 PM CST MONDAY FOR IAZ008>011- 018-019-029-030. && $$ SHORT TERM...AJ LONG TERM....AJ AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1135 AM CST SAT FEB 15 2014 .UPDATE... ISSUED AT 1135 AM CST SAT FEB 15 2014 HAVE ADDED IN WINNESHEIK AND FAYETTE COUNTIES INTO THE ADVISORY. 15.12Z AND 15.15Z RAP GUIDANCE...ALONG WITH RADAR TRENDS...SUGGEST THESE COUNTIES COULD ALSO PICK UP 2 TO 4 INCHES. ITS WORTH NOTING THAT THE 15.15Z RAP SUGGESTS SOME OF THE HEAVIER SNOW COULD EVEN SPREAD ONE MORE COLUMN OF COUNTIES EASTWARD...I.E. WABASHA TO CLAYTON. WILL MONITOR RADAR TRENDS TO SEE IF EXPANSION EASTWARD IS NEEDED. UPDATE ISSUED AT 1040 AM CST SAT FEB 15 2014 16Z WATER VAPOR LOOP SHOWS A FAIRLY IMPRESSIVE SHORTWAVE DIGGING SOUTHEAST THROUGH SOUTHWEST MN...HEADING TOWARDS NORTH CENTRAL IOWA. AHEAD OF THE SHORTWAVE...COMBINATION OF DPVA...ISENTROPIC LIFT AND SOME NEGATIVE EPV FLOWING IN HAS HELPED TO INVIGORATE A BAND OF SNOW ALONG/WEST OF I-35. IT TOOK A LITTLE BIT TO OVERCOME LOW LEVEL SATURATION ISSUES...SEEN ON THE 12Z MPX SOUNDING...BUT ONCE IT DID VISIBILITIES QUICKLY DROPPED FROM 10 MILES TO BASICALLY 1/4 MILE. SOME SNOWFALL REPORTS RECEIVED THUS FAR COURTESY OF NWS CHANHASSEN WERE 2.5 INCHES IN REDWOOD FALLS AND 1.5 INCHES IN MANKATO. WITH THESE SITES STILL SNOWING...LOOKS LIKE THEY COULD ACCUMULATE A QUICK 2 TO 4 INCHES. 16.11Z AND 16.12Z RAP13 -12 TO -18C OMEGA OUTPUT HAS LINED UP WELL WITH THE HEAVY RATES COMING OUT OF THIS SNOW BAND. FOLLOWING OUT IN TIME WOULD SUGGEST OUR FAR WESTERN 8 COUNTIES...BASICALLY MOSTLY ALONG AND WEST OF HIGHWAY 52...WOULD BE IMPACTED. GIVEN THE VISIBILITIES AND SNOWFALL REPORTS RECEIVED THUS FAR...HAVE ISSUED AN ADVISORY. ANOTHER FACTOR CONSIDERED TOO IS WINDS...WHICH HAVE BEEN SUSTAINED AROUND 15 KT IN THE ADVISORY AREA WITH GUSTS OF 20-25 KT. THIS WILL EASILY BLOW AND DRIFT SOME OF THE SNOW AROUND. MEANWHILE...FARTHER TO THE EAST...LOOKS LIKE MOST LOCATIONS EAST OF THE MISSISSIPPI RIVER ARE GOING TO GET MISSED BY MUCH OF THE SNOW. THIS IS BECAUSE THE TRACK OF THE SHORTWAVE IS HEADING SOUTHEAST...VERSUS EAST. THEREFORE...HAVE TRIMMED POPS AND SNOW AMOUNTS A LITTLE. && .SHORT TERM...(TODAY THRU SUNDAY) ISSUED AT 252 AM CST SAT FEB 15 2014 EVEN IN THIS FAST MOVING FLOW...TIMING OF SHORT TERM RIDGE EARLY THIS MORNING HAS LED TO ANOTHER SUB ZERO START. FAVORED COLD SPOTS OF WESTERN AND CENTRAL WISCONSIN /CRANBERRY COUNTY/ IN THE 10 TO 20 BELOW. MEANWHILE UPSTREAM...MULTITUDE OF SHORT WAVE TROUGHS WAIT IN THE WINGS WITH PRECIPITATION THREAT TODAY AND AGAIN MONDAY. FOCUS REMAINS ON THOSE SYSTEMS AND POTENTIAL IMPACT. STRONG JET RIDING OVER INTERMOUNTAIN UPPER RIDGE HELPING TO PUSH NEXT SHORT WAVE TROUGH INTO THE REGION TODAY. CLOUDS ALREADY ON THE INCREASE WITH PATCHY PRECIPITATION NOTED OVER THE NORTHERN PLAINS. DECENT MID LEVEL Q-G FORCING SHOULD CREATE ENOUGH LIFT FOR EXPANSION OF SNOW AS WAVE APPROACHES BUT HAVE SLOWED TIMING A LITTLE TO MAINLY THIS AFTERNOON...MOVING ACROSS RIVER BY EVENING. GENERAL SNOW AMOUNTS SHOULD BE IN 1 TO 2 INCH RANGE WITH SHORT DURATION SNOW. COULD BE SOME BANDS IN SNOW LEADING TO HIGHER SNOW RATES AND SHORT TERM IMPACT TO TRAVEL BUT EVEN WITH A LITTLE WIND...SEEMS TO BE A SUB ADVISORY TYPE OF DAY. ALTHOUGH LOOKING LESS AND LESS LIKELY...STILL SEE SUBTLE HINTS OF LOSS OF ICE IN TOP DOWN APPROACH LATE IN DAY ACROSS MAINLY NORTHEAST IOWA. SOME LIFT FOR A SHORT PERIOD AS WELL SO COULD NOT COMPLETELY RULE OUT A SHORT PERIOD OF FREEZING DRIZZLE. BETWEEN SYSTEMS...SUNDAY LOOKS QUIET AS SHORT TERM UPPER RIDGE PASSES THROUGH. SEASONABLY COOL DAY ON TAP. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 252 AM CST SAT FEB 15 2014 ACTIVE...LOWER AMPLITUDE FLOW WILL LEAD TO ANOTHER SHORT WAVE TROUGH COMING IN SUNDAY NIGHT AND MONDAY. A BIT STRONGER DYNAMICS WITH THIS ONE...DEEPER Q-G FORCING AND EVEN HINTS OF DUAL JET STRUCTURE WITH MORE DIVERGENCE ALOFT TO HELP SUPPORT STRONG LIFT. WARMER AIRMASS AND MORE MOISTURE TO WORK WITH AS WELL...SO ADVISORY CERTAINLY POSSIBLE HEADING INTO THE MONDAY MORNING COMMUTE. WHILE MODELS IN DECENT AGREEMENT WITH TIMING...SUBTLE DIFFERENCES IN TEMPERATURE PROFILES NOTED. GFS/ECMWF REMAIN A BIT COLDER WITH ALL SNOW...WHILE NAM REMAINS THE WARMER MODEL WITH SOME SLEET OR BRIEF FREEZING RAIN SCENARIOS IN PARTS OF NORTHEAST IOWA INTO SOUTHWEST WISCONSIN AROUND DAYBREAK MONDAY. MODELS ARE TRENDING COLDER AND STRONGER DYNAMICS SUPPORT THAT IDEA. EVEN IN WARMEST SCENARIO... TEMPERATURES ALOFT MAY ONLY WARM A DEGREE OR TWO ABOVE FREEZING ALLOWING FOR BRIEF SLEET PERIOD AT BEST SO SNOW ONLY SCENARIO SEEMS BEST TO GO WITH. AGAIN...FAST MOVING SYSTEM BUT SNOWFALL RATES COULD BE IMPRESSIVE FOR 2 TO 3 HOURS MONDAY MORNING. 2 TO 5 INCHES...WITH HIGHER AMOUNTS ALONG AND NORTH OF INTERSTATE 94 IN WISCONSIN. CERTAINLY EXPECTING TRAVEL PROBLEMS FOR HIGHWAYS AND SCHOOLS. TUESDAY AND WEDNESDAY LOOK QUIET AS ANOTHER SMALL SCALE RIDGE MOVES IN. STRONG JET PUSHING INTO PACIFIC NORTHWEST WILL KICK ANOTHER TROUGH INTO THE MIDWEST BY WEDNESDAY NIGHT THOUGH WITH MEDIUM RANGE GUIDANCE CONSISTENT IN SURGE OF WARMER AIR AND INFLUX OF MOISTURE BY LATER HALF OF NEXT WEEK. A LITTLE EARLY TO NAIL DOWN PRECIPITATION TYPES BUT COULD BE LOOKING AT SNOW IN NORTHWEST HALF OF FORECAST AREA WITH ALL RAIN TO THE SOUTHEAST. STILL CONCERNED THAT HIGHER QPF AND MELTING COULD LEAD TO SOME FLOODING ISSUES BUT WILL HAVE TO WAIT TO SEE HOW THIS SYSTEM EVOLVES IN FORECAST GUIDANCE NEXT FEW DAYS. TRACK OF SURFACE LOW AND DEFORMATION ZONE WITH HEAVIEST SNOW COULD ALSO TRACK ACROSS THE REGION SO PLENTY TO KEEP AN EYE ON IN LATER PERIODS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY) ISSUED AT 1135 AM CST SAT FEB 15 2014 BAND OF SNOW AHEAD OF LOW PRESSURE IN EASTERN SOUTH DAKOTA IS RAPIDLY APPROACH RST. VISIBILITIES QUICKLY DROP...FROM VFR TO LIFR/VLIFR AS THE SNOW MOVES IN. HAVE TRENDED THE 18Z TAF FOR RST IN THAT FASHION...WITH CEILINGS ALSO DROPPING FROM VFR TO IFR/LIFR. LOOKS LIKE THE PERIOD OF HEAVIER SNOW SHOULD BE SHORT LIVED AT RST...WITH VISIBILITIES AND CEILINGS CLIMBING TO IFR BY 22Z...MVFR BY 00Z AND VISIBILITIES TO VFR BY 02Z. MEANWHILE...AT LSE...SNOW BAND LOOKS TO MOVE IN AROUND 20Z WITH VISIBILITIES FALLING TO IFR AND CEILINGS TO MVFR. APPEARS THE SNOW SHOULD NOT BE AS HEAVY AT LSE BASED ON MODEL FORCING FORECASTS...THUS HAVE ONLY WENT AS LOW AS TEMPORARILY LIFR WITH VISIBILITIES BETWEEN 21-24Z. EXPECT VISIBILITIES TO CLIMB TO VFR BY 03Z AS THE SNOW DIMINISHES. LOOK FOR TOTAL SNOWFALL ACCUMULATIONS AT RST OF 3...MAYBE 4 INCHES...AND AT LSE OF UP TO 2 INCHES. AN MVFR STRATUS DECK WILL LIKELY LINGER AT BOTH TAF SITES THROUGH MUCH OF THE NIGHT...SCATTERING OUT TOWARDS 09-12Z AS DRIER AIR FLOWS IN FROM THE NORTHWEST. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR MNZ086- 087-094-095. IA...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR IAZ008>010-018-019-029. && $$ UPDATE...AJ SHORT TERM...SHEA LONG TERM...SHEA AVIATION...AJ
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1109 AM CST SAT FEB 15 2014 .UPDATE...SHORTWAVE CONTINUES TO APPROACH FROM SW MN. UPPER JET DRIVING IN AND ENHANCING SNOWS ACROSS NRN MO/SRN IA. MODELS HAVE BEEN CONSISTENT IN KEEPING BETTER UPPER JET RELATED FORCING LARGELY TO OUR SOUTH. DEF ZONE SNOWS PROGGD MORE TO OUR NORTH. AS THE ELONGATED NORTH/SOUTH BAND ACROSS IA SHIFTS EAST IT WILL BE AIDED BY DIFFERENTIAL CYCLONIC VORTICITY ADVECTION OF THE SHORTWAVE. MODEL QPF SOLUTIONS SHOWING A SPLIT WITH THE ABOVE SCENARIO LEAVING SRN WI WITH A RELATIVE MIN BETWEEN THE BETTER FORCING AREAS. THE HRRR SHOWS DRAMATIC WEAKENING OF PRECIP WITH TIME WHILE GFS/NAM/ECMWF SHOW THIS AS WELL WITH STILL A FEW HUNDREDTHS OF LIQUID. SO GIVEN THE CONSENSUS OF THE MODEL DATA THIS POINTS TOWARDS GOING LINE TO WEAKEN A BIT WITH TIME. SO IT LOOKS LIKE A QUICK HITTING EVENT FROM MID AFTERNOON THROUGH EARLY EVENING WITH AN INCH AT MOST FOR ALL OF SRN WI. PC && .AVIATION/18Z TAFS/...QUICK HITTING SNOW EVENT FROM MID AFTERNOON INTO EARLY EVENING. LOOKING AT AN INCH OR LESS IN MOST AREAS AS MODELS WEAKEN CURRENT VIGOROUS BAND ACROSS IA TRENDING HEAVIER SNOW NORTH AND SOUTH OF SRN WI. WILL CONTINUE TO MONITOR THESE TRENDS TO ENSURE WEAKENING PANS OUT AS SUGGESTED BY MODELS. EXPECTING CIGS AND VSBYS TO LOWER TO AT LEAST MVFR LEVELS WITH SOME IFR VSBYS LIKELY ESP IN SC WI WHERE BAND MAY STILL BE A BIT BETTER ORGANZIED. LOW LEVEL RH PROGS SUGGEST LOWER CLOUD DECK LINGERS INTO SUNDAY MORNING. PC && .PREV DISCUSSION... /ISSUED 339 AM CST SAT FEB 15 2014/ TODAY AND TONIGHT...FORECAST CONFIDENCE...HIGH MODELS CONTINUE TO DELAY MOVING LIGHT SNOW INTO SRN WITH THE SHORT TERM/HI RESOLUTION MODELS KEEPING THE FORECAST AREA DRY THROUGH 21Z AND BARELY REACHING A DELLS...MADISON TO JANESVILLE LINE BY 00Z. OTHER OPERATIONAL MODELS IN LINE WITH KEEPING AT LEAST THE LAKESHORE COUNTIES SNOW FREE UNTIL 00Z WITH SNOW TRACKING ACROSS REGION WITH BEST 500-300MB DIFFERENTIAL VORTICITY ADVECTION...AS ISENTROPIC UPGLIDE AHEAD OF SHORT WAVE WEAKENS AS IT MOVES INTO SRN WI AND RE- FOCUSES TO THE SOUTH OVER ILLINOIS. WILL HAVE A SHARP GRADIENT TO POPS LATE THIS AFTERNOON TO MATCH TIGHT CONDENSATION PRESSURE DEFICIT ON ISENTROPIC FORECASTS THAT CORRELATE WELL WITH COLUMN SATURATION ON FORECAST SOUNDINGS. CATEGORICAL POPS EVERYWHERE THIS EVENING...WITH ABOUT A 3-HOUR LONG PERIOD OF LIGHT TO MODERATE SNOW. QPF GRADIENT AS WELL...WITH AROUND 0.10 INCH IN THE SW TAPERING TO AROUND 0.05 IN THE NORTHEAST AND EAST. 15:1 TO 16:1 SNOW LIQUID RATIOS YIELD AROUND 1 INCH OVER MOST OF THE CWA WITH 1.5 TO 2 INCH AMOUNTS IN THE SOUTHWEST THIRD. MODELS HAVE 925MB THERMAL RIDGE OVER FORECAST AREA AT 00Z...TO DIFFERING MAGNITUDES. FORECAST SOUNDINGS ALL AGREE MIXING ONLY UP TO BETWEEN 935 TO 930 MB SO WENT COOLER THAN WHAT 925MB WOULD INDICATE WITH HIGHS IN THE TEENS TO AROUND 20...SIMILAR TO PREVIOUS FORECAST. NAM SLOWER WITH COLD ADVECTION OVERNIGHT AND IS 2C TO 3C WARMER THAN GFS/ECMWF AT 925 MB AT 12Z SUNDAY. LINGERING CLOUDS SUPPORT BLENDED TEMPS WHICH GIVE LOWS IN THE SINGLE DIGITS ABOVE INLAND...AND 10 TO 13 ABOVE ALONG THE LAKE. SUNDAY AND MONDAY...FORECAST CONFIDENCE...HIGH SHOULD BE DRY SUNDAY AS HIGH PRESSURE BRIEFLY SLIDES THROUGH. NORTHEAST WINDS OFF LAKE MICHIGAN WILL PROBABLY KEEP SKIES MOSTLY CLOUDY THROUGH AT LEAST THE MORNING IN THE EAST. HIGHS WILL REMAIN ABOUT 10 DEGREES BELOW NORMAL. LOW PRESSURE IS EXPECTED TO APPROACH THE AREA SUNDAY NIGHT...THEN MOVE THROUGH ON MONDAY. MODELS HAVE CONTINUED TO SHOW A COLDER SOUTHERN TRACK OF THE SFC LOW...SO REMOVED ANY MENTION OF MIXED PRECIPITATION AS ONLY SNOW IS EXPECTED AT THIS POINT. STRONG WARM ADVECTION IS EXPECTED THROUGH THIS EVENT...SO LOOKS LIKE PLENTY OF LIFT. TEMPERATURES AND THICKNESS VALUES SUGGEST LIQUID TO SNOW RATIOS OF 10-12 TO 1. STILL A DECENT RANGE IN QPF AMONG MODELS...SO USED CONSENSUS APPROACH...RESULTING IN SNOW AMOUNTS OF 4 TO 5 INCHES. TUESDAY AND WEDNESDAY...FORECAST CONFIDENCE...MEDIUM MODELS IN DECENT AGREEMENT WITH A SPELL OF MILDER TEMPS FOR THE MIDDLE OF THE WEEK. LOOKS MAINLY DRY TUESDAY AND WEDNESDAY WITH MID TO UPPER 30S FOR HIGH TEMPS. THURSDAY AND FRIDAY...FORECAST CONFIDENCE...LOW THE GFS REMAINS SIMILAR TO TUE/WED WITH TEMPS FOR THURSDAY...WITH SOME LIGHT RAIN MOVING THROUGH. THE ECMWF ON THE OTHER HAND STILL SHOWS A STRONG LOW LIFTING NORTHEAST THROUGH THE WESTERN FORECAST AREA...WITH STRONG SOUTHERLY FLOW BRINGING UP A DECENT AMOUNT OF RAIN AND TEMPS UP AROUND 50. CONTINUED TO SPLIT THE DIFFERENCE...WITH HIGHS NEAR 40...SIMILAR TO THE CANADIAN SOLUTION. DRY WEATHER IS EXPECTED FRIDAY...AS A COLDER AIRMASS MOVES IN BEHIND THE DEPARTING LOW. PRETTY GOOD SPREAD IN HIGH TEMPS BETWEEN THE GFS IN THE MID TO UPPER 20S AND ECMWF IN THE MID TO UPPER 30S. SPLIT THE DIFFERENCE IN TEMPS FOR NOW. AVIATION/12Z TAFS/...CLEAR SKIES WITH SURFACE TO 850 MB RIDGING AND LIGHT WINDS. WILL SEE VFR CONDITIONS AT KMSN UNTIL MID TO LATE AFTERNOON AND 00Z AT EASTERN TAF SITES. HIGH TO MID-LEVEL CLOUDS SPREAD IN AHEAD OF APPROACHING SHORT WAVE TROUGH...WITH SNOW AND MVFR CIGS/VSBYS WITH OCCASIONAL IFR VSBYS REACHING KMSN AROUND 21Z...KUES BETWEEN 22Z AND 23Z AND KMKE AND KENW AROUND 00Z. EXPECTING AROUND A 3-4 HOUR LONG PERIOD OF SNOW WITH ACCUMULATIONS AROUND 1 INCH AT ALL TAF SITES. MVFR CIGS WILL HOLD IN AT ALL SITES THROUGH THE REMAINDER OF THE FORECAST. NOT MUCH WIND SO BLOWING/DRIFTING WILL NOT BE A BIG PROBLEM. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ TODAY/TONIGHT AND AVIATION/MARINE...REM SUNDAY THROUGH FRIDAY...DDV
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
416 AM MST SAT FEB 15 2014 .SHORT TERM...(TODAY THROUGH MONDAY NIGHT) ISSUED AT 400 AM MST SAT FEB 15 2014 WIND HAS INCREASED SINCE MIDNIGHT OVER MUCH OF THE LOWER ELEVATIONS IN SOUTHEAST WYOMING. LAR HAD A GUST TO 52 KTS AND CYS A GUST TO 47 KTS. THE WINDS HAVE INCREASED JUST AS THE GFS SHOWED AN AXIS OF 60 KT 700MB WINDS STRETCHING FROM RAWLINS TO CHEYENNE. WILL KEEP THE HIGH WIND WARNINGS GOING AS IS...ALTHOUGH THE WINDS SHOULD DECREASE AFTER SUNRISE AS PRESSURE RISES OCCUR OVER THE PLAINS. A WEAK FRONT IS PROGGED TO PUSH SOUTHWARD TO THE EAST OF THE LARAMIE RANGE THROUGH THE MORNING. THERE IS ENOUGH LLVL CONVERGENCE AND WEAK MIDLEVEL FRONTOGENESIS TO GENERATE LIGHT QPF BEHIND THE SFC BOUNDARY. TEMPERATURES IN THE MID-TO-UPPER 30S WOULD SUPPORT A MIX OF RAIN AND SNOW. SFC WINDS CLOSER TO THE COLORADO BORDER NEVER REALLY GO NORTHERLY...BUT STAY WEST- NORTHWESTERLY AND DOWNSLOPE WHICH WILL KEEP PRECIP CHANCES LOWER IN LARAMIE AND ALBANY COUNTIES. MOIST 700-500MB NORTHWESTERLY FLOW WILL KEEP OROGRAPHIC SNOWS GOING IN THE SIERRA MADRE AND SNOWY RANGES THROUGH LATE MORNING...HOWEVER ONLY LIGHT ACCUMULATIONS (AN ADDITIONAL 1-3 INCHES) IS EXPECTED. SHORTWAVE RIDGE MOVES OVER THE REGION TONIGHT AND WINDS ACROSS SOUTHEAST WYOMING WILL DECREASE OVER THE PERIOD FROM LATE THIS MORNING THROUGH TONIGHT. THE BREAK IN THE WIND IS REALLY SHORT LIVED AS A SHORTWAVE QUICKLY APPROACHES THE REGION ON SUNDAY WITH PRESSURE FALLS OCCURRING DURING THE DAY IN ADVANCE OF IT. WINDS COULD BE CLOSE TO HIGH WIND CRITERIA IN THE WIND PRONE AREAS (ESPECIALLY ARLINGTON AND BORDEAUX) ON SUNDAY AFTERNOON AND EVENING. SHORTWAVE IS REALLY PROGRESSIVE...AND WHILE SNOW WILL BECOME LIKELY OVER THE SIERRA MADRE AND SNOWY RANGES BY SUN AFTN...IT WILL END BY SUN EVENING IN THE SUBSIDENCE BEHIND THE SYSTEM. STRONG ZONAL FLOW ALOFT WILL COMBINE WITH A STRONG PRESSURE GRADIENT TO MAINTAIN WINDY CONDITIONS OVER SOUTHEAST WYOMING THROUGH MONDAY. TEMPS WILL BE MILD...ESPECIALLY ON SUN AND MON...WHEN HIGHS IN THE 50S WILL BE COMMON OVER THE PLAINS. .LONG TERM...(TUESDAY THROUGH SATURDAY) ISSUED AT 400 AM MST SAT FEB 15 2014 PROGRESSIVE ZONAL FLOW WILL DOMINATE NEXT WEEK WITH A DEEPER TROUGH AND COLDER AIR MASS ARRIVING FOR THE SECOND HALF OF THE WEEK. WINDS WILL BE THE MAIN CONCERN DURING THE MIDDLE OF NEXT WEEK...ESPECIALLY FOR AREAS ALONG AND WEST OF I-25. WOULD NOT BE SURPRISED IF TUESDAY NIGHT AND WEDNESDAY MORNING NEEDS ANOTHER WIND HIGHLIGHT FOR THE WIND PRONE AREAS IN TIME AS SHORTWAVE ENERGY AND REFLECTED SFC LOW STRENGTHENS PREFRONTAL LLVL GRADIENTS. BY WEDNESDAY AFTERNOON...BOTH MEDIUM RANGE MODELS ARE CONSISTENT IN TRACKING A COLD FRONT THRU THE CWFA. ASIDE FROM PERHAPS A BRIEF BORA EVENT WITH THE FRONT...EXPECT WINDS TO BE LESS FOR THE THURSDAY THROUGH SATURDAY TIMEFRAME AS THE COLDER AIR MASS TAKES CONTROL. BEST PRECIPITATION CHANCES THROUGH THE PERIOD WILL FALL IN THE SNOWY/SIERRA MADRE RANGES WHERE PERSISTENT QUICK ZONAL FLOW ENHANCES OROGRAPHIC ASCENT. AS FOR LOWER ELEVATIONS...EXPECT A BRIEF PERIOD ASSOCIATED WITH FROPA WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT...WITH PERHAPS ANOTHER PERIOD OF LIGHT SNOW ON FRIDAY AS THE COLD AIR MASS IS REINFORCED BY A SECOND FRONT. AT THIS POINT...ONLY LIGHT ACCUMULATIONS WILL BE POSSIBLE OUTSIDE OF THE MOUNTAINS. THE WARMER PREFRONTAL AIR MASS WILL YIELD TUESDAY AND WEDNESDAY AS THE WARMEST DAYS OF THE PERIOD. ON THESE DAYS H7 TEMPERATURES OF -2C TO -6C WILL YIELD AFTERNOON HIGHS CLOSE TO 40 WEST OF THE LARAMIE RANGE...WITH UPPER 40S TO LOW 50S OUT ON THE EASTERN PLAINS. OF COURSE THE EASTERN PLAINS TEMPERATURES WILL BE ENHANCED BY DOWNSLOPE ASSUMING LEE-SIDE LENTICULARS DONT CUT INTO HIGHS. THIS ALL CHANGES FOR THURSDAY THROUGH SATURDAY HOWEVER AS H7 TEMPS PLUMMET TO -10C TO -13C. AS SUCH HIGHS WILL FALL BACK INTO THE 30S BY THE END OF THE WEEK...WITH EVEN SOME 20S FOR SATURDAY. WITH CLIMATOLOGYS INFLUENCE ON MOS DATA...THESE MAY EVEN BE A BIT OPTIMISTIC. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY EVENING) ISSUED AT 1035 PM MST FRI FEB 14 2014 STILL SOME CONCERNS FOR LOWERING FLIGHT CONDITIONS AS A COLD FRONT SAGS INTO THE AREA FROM THE NORTHWEST. TIMING ON THE FRONT LOOKS TO BE AROUND THE 12Z TIME FRAME WITH SNOW DEVELOPING OVER THE LARAMIE RANGE AND POSSIBLY OUT BY LARAMIE AT THAT TIME. OF NOTE...THE LATEST HRRR FORECAST KEEPS THE PANHANDLE VFR THROUGH 12Z...SO CONFIDENCE IS SOMEWHAT HIGH THAT OUR AIRPORTS OUT THAT WAY WILL BE FINE. && .FIRE WEATHER... ISSUED AT 400 AM MST SAT FEB 15 2014 MINIMAL FIRE WEATHER CONCERNS THROUGH EARLY NEXT WEEK. TEMPERATURES WILL BE 10-15 DEGREES ABOVE NORMAL BUT MINIMUM AFTERNOON HUMIDITY VALUES WILL GENERALLY BE ABOVE 30 PERCENT. WINDY CONDITIONS WILL PERSIST THROUGH THE MIDDLE PART OF NEXT WEEK...ESPECIALLY ACROSS SOUTHEAST WYOMING. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...HIGH WIND WARNING UNTIL NOON MST TODAY FOR WYZ106-110-114-116- 117. HIGH WIND WARNING UNTIL 5 AM MST EARLY THIS MORNING FOR WYZ104- 109-115. NE...NONE. && $$ SHORT TERM...FINCH LONG TERM...HAHN AVIATION...CLAYCOMB FIRE WEATHER...FINCH
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1038 PM MST FRI FEB 14 2014 .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 355 PM MST FRI FEB 14 2014 CURRENT OBSERVATIONS ACROSS THE AREA SHOW WINDS JUST STARTING TO INCREASE OVER SOUTHEAST WYOMING AND THE LAPS ANALYSIS SHOWS SURFACE PRESSURE FALLS TO THE EAST OF THE MOUNTAINS. WINDS AT ARLINGTON HAVE INCREASED ALL AFTERNOON AND ARE NOW OBSERVING GUSTS AROUND 50 MPH. WINDS WILL CONTINUE TO INCREASE THIS EVENING WITH GUSTS AROUND 60 MPH BY SUNSET. THE WEAK CLIPPER...WHICH IS PLAYING A ROLE IN THE HIGH WINDS FOR TONIGHT...WILL DIG SOUTHEAST INTO THE DAKOTAS AS AN ASSOCIATED COLD FRONT SLIDES SOUTH AND STALLS ACROSS THE FORECAST AREA LATE TONIGHT AND EARLY SATURDAY. SNOWFALL IS LOOKING MORE LIKELY ACROSS THE HIGH PLAINS OF SE WYOMING AND IN THE MOUNTAINS TONIGHT THROUGH SATURDAY MORNING. WILL HAVE TO MONITOR SNOWFALL AMOUNTS SINCE THE SREF IS SHOWING DECENT QPF AMOUNTS ACROSS THE SNOWY RANGE...ALBANY COUNTY...AND PORTIONS OF PLATTE AND CONVERSE COUNTY INCLUDING THE NORTHERN LARAMIE RANGE. LLVL CONVERGENCE NEAR THE FRONT AND UPPER LEVEL JET DYNAMICS MAY RESULT IN MODERATE TO LOCALLY HEAVY SNOWFALL RATES FOR A WHILE TONIGHT. 3 TO 6 INCHES OF SNOW IS POSSIBLE IN THE SNOWY RANGE AND NORTHERN LARAMIE RANGE...BUT WITH HIGH WINDS BEING THE MAIN HAZARD...WILL JUST MENTION THE SNOW POTENTIAL IN THE HIGH WIND WARNING FOR THE SNOWY RANGE. THE LOWER ELEVATIONS ARE A LITTLE MORE TRICKY DUE TO SNOW LEVELS AND SOMEWHAT WARMER TEMPERATURES AHEAD OF THE FRONT. FOR NOW...EXPECT 1 TO 2 INCHES OF SNOW NORTH OF A LINE FROM LARAMIE TO CHADRON NEBRASKA. WOULD NOT BE SURPRISED IF A FEW AREAS OBSERVE NEAR 4 INCHES IN THE HEAVIER SNOW BANDS. HOWEVER...DID NOT ISSUE A WINTER WEATHER ADVISORY SINCE THERE IS LOW CONFIDENCE ON WHERE THESE AREAS MIGHT BE. THERE IS ADDITIONAL CONCERN THAT ANY HEAVIER SNOWFALL MAY ACCUMULATE RAPIDLY SINCE TEMPERATURES DID NOT GET AS WARM AS PREVIOUSLY EXPECTED DUE TO CLOUD COVER AND SOME REMAINING SNOW PACK. FURTHER SOUTH ALONG I80...LITTLE OR NO SNOW IS EXPECTED AS THE FRONT STALLS NEAR THE COLORADO BORDER. INCREASED POP BETWEEN 60 TO 80 PERCENT ALONG AND NORTH OF THE PLATTE RIVER VALLEY IN ADDITION TO ALBANY COUNTY...WITH LOWER VALUES FURTHER SOUTH. BY SATURDAY AFTERNOON...DRIER WEATHER IS EXPECTED THROUGH SATURDAY NIGHT AS A SHORTWAVE RIDGE MOVES OVER THE FORECAST AREA. HIGH TEMPERATURES WILL CLIMB INTO THE 40S ACROSS MOST OF THE AREA...BUT REMAIN NEAR 40 FURTHER NORTH. STILL KEPT HIGH TEMPERATURES A FEW DEGREES BELOW MOS SINCE THERE HAS BEEN A BIT OF A WARM BIAS RECENTLY. GUSTY WEST TO SOUTHWEST WINDS ARE LIKELY AGAIN LATE SATURDAY NIGHT INTO SUNDAY MORNING AS THE NEXT COLD FRONT MOVES TOWARDS THE AREA. IN ADDITION...GUSTS UP TO 60 MPH ARE POSSIBLE OVER THE WIND PRONE AREAS WEST OF THE LARAMIE RANGE. ALTHOUGH SOME PRECIPITATION IS EXPECTED WITH THIS NEXT FRONT ON SUNDAY...EXPECT IT TO BE LIGHT SINCE THIS UPPER LEVEL DISTURBANCE IS MORE PROGRESSIVE IN NATURE AND WILL QUICKLY EXIT THE AREA SUNDAY NIGHT. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 330 PM MST FRI FEB 14 2014 LIKE YESTERDAY...FORECAST CHALLENGES WILL FOCUS ON WINDS...PRECIPITATION AND TEMPERATURES. THE 12Z NUMERICAL MODEL GUIDANCE CONTINUES TO DEPICT A PROGRESSIVE ZONAL FLOW ALOFT THROUGH MIDWEEK...FOLLOWED BY A MORE AMPLIFIED WESTERN CONUS TROUGH/EASTERN CONUS RIDGE BY WEEK`S END. BOTH MONDAY AND TUESDAY WILL BE BETWEEN PACIFIC WEATHER SYSTEMS WITH DRY...WINDY AND MILD CONDITIONS WITH SURFACE HIGH PRESSURE OVER COLORADO AND LEE TROUGH OVER THE HIGH PLAINS. THE CRAIG TO CASPER 700/850MB GRADIENTS WILL RANGE BETWEEN 55 AND 65M. 700MB WINDS WILL LIKEWISE PEAK BETWEEN 55 AND 65KT IN THE VICINITY OF THE LARAMIE RANGE. THE POTENTIAL FOR HIGH WIND EVENT FROM MONDAY AFTERNOON THROUGH TUESDAY FOR WIND PRONE AREAS OF SOUTHEAST WY IS LOOKING BETTER WITH TODAY`S MODEL RUN. TEMPERATURES WILL AVERAGE 10 TO 15 DEGREES ABOVE SEASONAL NORMALS WITH HIGHS IN THE 40S AND 50S LOWER ELEVATIONS WITH 30S FOR THE HIGHER TERRAIN. ABUNDANT PACIFIC MOISTURE ARRIVES WEDNESDAY WITH PRECIPITATION (LOW ELEVATION RAIN AND HIGH ELEVATION SNOW) DEVELOPING FROM THE LARAMIE RANGE WESTWARD. DOWNSLOPE LOW LEVEL FLOW WILL LIMIT THE COVERAGE OF PRECIPITATION ACROSS THE HIGH PLAINS WEDNESDAY NIGHT. IT WILL TURN COOLER FOR AREAS OUT WEST BEHIND THE PACIFIC FRONT WITH 20S AND 30S... WHILE IT REMAINS MILD EAST WITH 40S AND 50S. WITH HIGHER SNOW LEVELS...SNOW ACCUMULATIONS WILL BE LIGHT. CROSS MOUNTAIN FLOW REMAINS HIGH FOR WINDY CONDITIONS FOR WIND PRONE AREAS OF SOUTHEAST WY. THURSDAY WILL BE BETWEEN PACIFIC SYSTEMS ONCE AGAIN WITH MAINLY DRY CONDITIONS EXCEPT FOR THE MOUNTAINS WHERE SOME OROGRAPHIC SNOW SHOWERS WILL LINGER. IT WILL BE COOLER THURSDAY WITH HIGHS CLOSER TO SEASONAL NORMALS. PRESSURE GRADIENT REMAINS TIGHT WITH THE APPROACH OF THE NEXT PACIFIC COLD FRONT SO GUSTY WESTERLY WINDS WILL CONTINUE. TROUGH DEEPENS OVER THE ROCKIES FRIDAY. COLD FRONT WILL BE THROUGH THE CWA BY FRIDAY MORNING WITH STRONG COLD AIR ADVECTION AND MORE WIDESPREAD POST-FRONTAL SNOW. PRESSURE GRADIENT RELAXES WITH BRISK WEST TO NORTHWEST WINDS. BELOW SEASONAL NORMAL TEMPERATURES WITH HIGHS IN THE 20S AND 30S VALLEYS AND HIGH PLAINS AND TEENS FOR THE MOUNTAINS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY EVENING) ISSUED AT 1035 PM MST FRI FEB 14 2014 STILL SOME CONCERNS FOR LOWERING FLIGHT CONDITIONS AS A COLD FRONT SAGS INTO THE AREA FROM THE NORTHWEST. TIMING ON THE FRONT LOOKS TO BE AROUND THE 12Z TIME FRAME WITH SNOW DEVELOPING OVER THE LARAMIE RANGE AND POSSIBLY OUT BY LARAMIE AT THAT TIME. OF NOTE...THE LATEST HRRR FORECAST KEEPS THE PANHANDLE VFR THROUGH 12Z...SO CONFIDENCE IS SOMEWHAT HIGH THAT OUR AIRPORTS OUT THAT WAY WILL BE FINE. && .FIRE WEATHER... ISSUED AT 219 PM MST FRI FEB 14 2014 MINIMAL FIRE WEATHER CONCERNS THROUGH NEXT WEEK. MINIMUM AFTERNOON HUMIDITIES WILL FALL TO AROUND 20 TO 30 PERCENT BY SUNDAY WITH GUSTY WINDS ACROSS THE HIGH PLAINS. PERIODS OF RAIN AND SNOW ARE EXPECTED FURTHER NORTH TONIGHT AND AGAIN SUNDAY NIGHT...MAINLY NORTH OF THE I80 CORRIDOR. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...HIGH WIND WARNING UNTIL NOON MST SATURDAY FOR WYZ106-110-114-116- 117. HIGH WIND WARNING UNTIL 5 AM MST SATURDAY FOR WYZ104-109-115. NE...NONE. && $$ SHORT TERM...TJT LONG TERM...JAMSKI AVIATION...CLAYCOMB FIRE WEATHER...TJT
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
330 AM CST MON FEB 17 2014 .DISCUSSION... 330 AM CST SHORT TERM (THROUGH TONIGHT)... MAIN CONCERNS ARE WITH INCREASED POTENTIAL FOR A PERIOD OF HEAVY SNOW THIS AFTERNOON FOR THE ENTIRE CWA WHICH COULD HAVE SIGNIFICANT IMPACTS WITH WHITE OUT CONDITIONS UNDER POSSIBLE TWO TO THREE INCH PER HOUR SNOWFALL RATES SOME OF WHICH COULD FALL UNDER CONVECTIVE ELEMENTS...WITH AREA WIDE 4 TO 8 INCHES LIKELY AND SOME ISOLATED AMOUNTS NEAR 10 INCHES DEFINITELY NOT OUT OF THE QUESTION. IMPRESSIVE STRONG STORM ANTICIPATED TO TAKE SHAPE OVER THE AREA LATER TODAY CAN BE OBSERVED ON SATELLITE IMAGERY...WITH MID/UPPER LEVEL TROUGH CURRENTLY PUSHING EAST THROUGH THE NORTHERN PLAINS. OUT AHEAD OF THIS SYSTEM...LATEST RAP ANALYSIS DEPICTING STRONG ISENTROPIC ASCENT OCCURRING ACROSS THE ENTIRE REGION INCLUDING LOCALLY OVER THE CWA. THIS HAS RESULTED IN PERSISTENT MID/HIGH LEVEL CLOUD COVER TO STREAM OUT AHEAD OF THIS SYSTEM...WITH CURRENT RADAR IMAGERY LIGHTING UP WITH SOME DECENT RETURNS. ALTHOUGH RATHER DRY AIR IN PLACE HAS LIMITED ANY PRECIP TO REACH THE SURFACE AND ANTICIPATE FOR THIS TO FURTHER BE THE CASE OVER THE NEXT COUPLE OF HOURS. WHAT COULD BE EXPECTED IN THE NEAR TERM ARE SOME ISOLATED FLURRIES PRIMARILY OVER THE NORTHWEST HALF OF THE CWA...WITH RFD CURRENTLY REPORTING 9 MILES IN LIGHT SNOW. ISENTROPIC ASCENT WILL CONTINUE THIS MORNING...WITH SHORT TERM GUIDANCE HINTING AT THE POSSIBILITY FOR FURTHER PRECIP DEVELOPMENT ENTERING THE SOUTHWEST CWA JUST AFTER THE 12Z TIME FRAME. PREVIOUSLY DISCUSSED WARMING/WARM WEDGE STILL ANTICIPATED HERE THIS MORNING AND COULD INITIALLY BRING A WINTRY MIX BUT STAYING CONFINED TO THE SOUTHERN HALF OF THE CWA...PRIMARILY SOUTH OF THE I80 CORRIDOR. IF ANYTHING WERE TO OCCUR DURING THIS TIME FRAME...ANTICIPATE IT TO BE ON THE LIGHTER SIDE WITH THE PREVIOUSLY MENTIONED DRIER AIR STILL NEEDING TO BE OVERCOME. NONETHELESS...WITH AN ANTICIPATED SLOWING TREND WITH THE EVOLUTION OF TODAY`S SYSTEM...THIS WINTRY MIX COULD BE MORE PREVALENT THAN PREVIOUSLY THOUGHT TO START THE PERIOD. SO HAVE INCLUDED CHANCE ZR/IP IN THE GRIDS THROUGH 15Z. CAN MAKE OUT TWO SEPARATE PIECES OF STRONG ENERGY TRAVERSING THE MID LEVEL FLOW...NOW WITH ALL GUIDANCE IN STRONG AGREEMENT WITH THE EVOLUTION OF THIS ENERGY AS IT APPROACHES THE REGION. ABOUT THE ONLY DIFFERENCE AT THIS TIME IS SOME SLIGHT TIMING DIFFERENCES WITH THE APPROACH OF THE BETTER FORCING/PRECIP LATER TODAY. A CONTINUED SLOWER TREND HAS BEEN THE PREFERRED TREND HERE THIS MORNING...AND HAVE DELAYED HIGHEST POPS TODAY. ALTHOUGH DID NOT OVERLY STRAY TOO MUCH WITH THE PREVIOUSLY MENTIONED ISENTROPIC ASCENT AND POTENTIAL PRECIP OUT AHEAD OF IT. HAVE CONTINUED THE MENTION IN THE GRIDS FOR A MIX OF SLEET FOR LATER IN THE MORNING...MAINLY FOR THE SOUTHERN TIER OF COUNTIES. ALTHOUGH THERMAL PROFILES WOULD BE SUPPORTIVE OF THIS WINTRY MIX CONTINUING...HAVE LIMITED MENTION OF THIS MIX AS BETTER FORCING SHOULD BE ARRIVING DURING THIS TIME. WHATEVER LINGERING WARM WEDGE IN THE COLUMN WILL QUICKLY COOL THE COLUMN TO THE WET BULB AS STRONG DYNAMIC FORCING ARRIVES...WITH ANY MIX QUICKLY CHANGING OVER TO ALL SNOW. ONCE AGAIN...ALL GUIDANCE POINTING AT SIGNIFICANT SNOWFALL RATES BEGINNING AT SOON AS LATE MORNING FOR THE WESTERN CWA. TWO PIECES OF ENERGY WILL PHASE TOGETHER BY EARLY AFTERNOON...WITH THIS MID/UPPER LEVEL TROUGH BECOMING NEGATIVELY TILTED. AS THIS OCCURS...ATTENDANT LOW TO DEEPEN AS IT MOVES THROUGH CENTRAL ILLINOIS WITH 850MB LOW REALLY BEGINNING TO TAKE SHAPE. STRONG DYNAMICAL FORCING ASSOCIATED WITH THIS MID LEVEL TROUGH AND SIGNIFICANT HEIGHT FALLS WILL ALLOW FORCING TO SWING THROUGH THE CWA BY LATE MORNING INTO THE EARLY AFTERNOON. ASSOCIATED FRONTOGENETICAL FORCING WILL LIKEWISE PUSH EAST THROUGH THE AREA THIS AFTERNOON...WITH THE PRESENCE OF NEGATIVE EPV. THIS PRESENCE OF BOTH SLANTWISE AND UPRIGHT MOTIONS ARE LEADING FOR SOME REALLY IMPRESSIVE VERTICAL MOTION...WITH FORECAST OMEGA AMONG ALL GUIDANCE SOME OF THE HIGHEST IVE OBSERVED IN SOME TIME. THE STRONGEST VERTICAL MOTIONS ARE EXPECTED TO PUSH EAST TO WEST ACROSS THE CWA INTO THE EARLY AFTERNOON TIME FRAME AND CONTINUING THROUGH MID/LATE AFTERNOON...WITH FORCING CENTERED RIGHT IN THE MIDDLE OF THE CWA. ALTHOUGH CURRENT FORECAST SNOW TOTALS ARE THE HIGHEST IN THESE LOCATIONS...TOTALS DONT STRAY TOO MUCH FROM THE AMOUNTS ACROSS THE REMAINING CWA. THIS IS IN DUE TO PART TO HOW UNSTABLE THIS SYSTEM WILL BE...INCLUDING CONVECTIVE INSTABILITY. BOTH NAM/GFS SHOWING IMPRESSIVE MUCAPE TO PUSH NORTHEAST THROUGH THE CWA AS EARLY AS MID MORNING...AND THE BEGINNING STAGES OF THIS CAN ALREADY BE OBSERVED TO OUR WEST/SOUTHWEST WITH LATEST RAP ANALYSIS DEPICTING 100-200 J/KG OVER IOWA/MISSOURI/KANSAS. WITH SREF GUIDANCE INDICATING HIGH PROBABILITIES OF AT LEAST 50-100 J/KG OF MUCAPE TO MOVE OVERHEAD LATER TODAY...FEEL THAT THE NAM/GFS SOLUTION OF 100 TO ALMOST 300 J/KG IS NOT OF THE QUESTION. THE PRESENCE OF THIS STRONG FORCING...STRONG INSTABILITY AND ABUNDANCE OF MOISTURE NOT ONLY LIKELY BEING PRESENT BUT ALSO COMING TOGETHER...HAS STEERED THE FORECAST SIGNIFICANTLY MORE PESSIMISTIC THIS MORNING. HEAVIEST SNOW...WHICH WILL FALL WITH HIGH INTENSITIES AND POSSIBLY AT A RATE OF TWO TO THREE INCHES PER HOUR AT TIMES SHOULD ARRIVE THE FAR WESTERN CWA BY MID/LATE MORNING...AND THEN SPREADING EAST THROUGH THE REMAINING CWA BY EARLY AFTERNOON. EXPECT THESE HIGH SNOWFALL INTENSITIES THROUGH MID TO LATE AFTERNOON...AND POSSIBLY CONTINUE INTO THE EARLY EVENING FOR THE EASTERN THIRD OF THE CWA. THIS HEAVY SNOW WILL QUICKLY ACCUMULATE ON ROADS WITH NEAR VISIBILITY LIKELY UNDER THIS HEAVY SNOW...CREATING VERY HAZARDOUS CONDITIONS. AS WAS MENTIONED PREVIOUSLY...THE HIGHEST TOTALS ARE IN THE CWA ALIGNED WITH THE BETTER FORCING...BUT FEEL THAT ANY LACKING FORCING WILL BE SUPPLEMENTED WITH THE CONVECTIVE NATURE OF THIS SYSTEM. CONVECTIVE ALLOWING MODELS INDICATE THE PRESENCE OF THUNDER BREAKING OUT BY EARLY AFTERNOON. ALTHOUGH GUIDANCE IS HINTING THAT THIS WILL BE MORE PREFERRED ACROSS THE SOUTHERN CWA...WITH GUIDANCE INDICATING INSTABILITY INTO SOUTHERN WISCONSIN...HAVE INCLUDED A CHANCE FOR THUNDER IN THE GRIDS FOR THE ENTIRE CWA. ITS THESE CONVECTIVE ELEMENTS WHICH COULD SUPPLEMENT HIGHER RATES AND RESULTANT SNOWFALL TOTALS. SO FOR THE WARNING ISSUED OVERNIGHT...WILL HAVE AREA WIDE 4 TO 8 INCHES WITH THE POSSIBILITY OF SLIGHTLY HIGHER AMOUNTS NEAR 10 INCHES. IF THESE CONVECTIVE ELEMENTS WERE TO MATERIALIZE...THEN AREAS DEFINITELY COULD OBSERVE THESE HIGHER AMOUNTS. ALSO...ITS POSSIBLE THAT THESE AMOUNTS COULD BE OBSERVED IN A 4-6 HOUR WINDOW. HAVE THE WARNING ENDING EARLY THIS EVENING FOR THE WESTERN CWA AND THEN AT 3Z LATER THIS EVENING FOR THE EASTERN CWA. IF LATER GUIDANCE THIS MORNING CONTINUES TO SUPPORT CURRENT THINKING...SITUATION FORECAST TO UNFOLD LATER THIS AFTERNOON WILL DEFINITELY BE SOMETHING TO NOT TAKE LIGHTLY. RODRIGUEZ LONG TERM (TUESDAY THROUGH SUNDAY)... FAST ON THE HEELS OF TODAY`S DEPARTING SYSTEM WILL BE ANOTHER NORTHERN STREAM SYSTEM TRACKING ACROSS SOUTHERN CANADA. VERY STRONG WARM AIR ADVECTION WILL BE UNDERWAY ALOFT TUES MORNING AND EVENTUALLY DEVELOPING AT THE SURFACE AS SOUTHERLY WINDS PICK UP. DEEP AND FRESHLY RELOADED SNOW COVER OVER THE AREA WILL UNDOUBTEDLY RETARD THE WARM UP...BUT STILL THINK TEMPS SHOULD MANAGE TO CLIMB ABOVE FREEZING MOST AREAS FOR THE FIRST TIME IN WEEKS TUES AFTERNOON. WEAK COLD FRONT MOVES THROUGH TUESDAY EVENING WITH LITTLE FANFARE AND BARELY TIME FOR MUCH COLD AIR TO SEEP SOUTHWARD BEFORE WARM AIR ADVECTION BEGINS AGAIN LATER WEDNESDAY IN ADVANCE OF LATE WEDNESDAY NIGHT INTO THURSDAY`S WELL ADVERTISED BIG HULLABALOO. NOT SURPRISINGLY GIVEN THE COMPLEXITY OF THE PATTERN AND DEALING WITH PHASING ISSUES...MODELS HAVE FLOPPED BACK FROM THEIR PREVIOUS FLIP WITH MORE EMPHASIS ON A STRENGTHENING SOUTHERN LOW LIFTING NORTHEAST INTO THE GREAT LAKES. STILL SOME DIFFERENCES IN STRENGTH AND EXACT TRACK...BUT ECMWF/GFS NOW AGREE ON TAKING A SFC LOW OVER NORTHERN MISSOURI 18Z THURS NORTHEAST TO THE UPPER GREAT LAKES BY THURSDAY NIGHT...WITH CONSIDERABLE DEEPEN OF THE LOW ALONG THE WAY. ECMWF AND 06Z NAM ARE STRONGER AND A BIT FARTHER NORTHWEST...BUT NAM/GFS/ECMWF ALL HAVE THE SAME GENERAL IDEA. FIRST FORECAST ISSUE WILL BE WEDNESDAY NIGHT AS INITIAL BATCH OF WAA PRECIP BREAKS OUT AND LIFTS NORTH ACROSS THE AREA. MODEL QPF REMAINS FAIRLY HIGH AND WITH SOME ELEVATED INSTABILITY ALSO EVIDENT IN THE MODELS...CERTAINLY ENOUGH TO WARRANT A CONTINUED SLIGHT CHANCE MENTION OF THUNDERSTORMS. THE BIGGEST PROBLEM WED NIGHT WILL BE HOW FAST THE 2M TEMPS WARM UP. WHILE VERY STRONG WAA WILL BE TAKING PLACE ALOFT...INITIALLY EASTERLY WINDS OVER THE AREA AND DEEP SNOW PACK COULD ALLOW FOR A RATHER PROLONGED PERIOD OF FREEZING RAIN AND AN ICING THREAT DEPENDING ON SFC TEMPS. MANY OF THE MODEL SUGGEST A SURGE OF WARM LATE WEDNESDAY NIGHT...ESPECIALLY SOUTHERN CWA...BUT ITS GOING TO BE CLOSE. ONLY A MATTER OF A COUPLE DEGREES COULD MEAN THE DIFFERENCE BETWEEN A SIGNIFICANT ICING PROBLEM AND ALL RAIN AND THIS FAR OUT IT REALLY IS ANYONE`S GUESS WHAT SIDE OF 32F ANY ONE GIVEN AREA WILL END UP ON AS THE RAIN FALLS. CERTAINLY FARTHER NORTH WOULD STAND THE BETTER CHANCE OF FREEZING RAIN...BUT THE ICING POTENTIAL CANNOT BE RULED OUT EVEN OVER SOUTHERN PORTIONS OF THE CWA. THIS LATEST SWING IN THE MODELS TOWARD A MORE AMPLIFIED SOUTHERN LOW TRACKING NORTH IS BAD NEWS FOR IN THE HYDROLOGY DEPARTMENT. WHILE NOT AS HORRIFYING AS THE NIGHTMARE SCENARIO THE ECMWF HAD BEEN PAINTING A COUPLE DAYS AGO WITH 50 AND NEAR 60F DEWPOINTS TO THE WISCONSIN LINE...THE LATEST GUIDANCE DOES DRAG THE 40F ISODROSOTHERM FAR NORTH INTO THE AREA ON THURSDAY...WITH EVEN SOME 50F DEWPOINTS FAR SOUTHERN CWA. THE HIGHER THE DEWPOINTS THE MORE RAPID THE SNOW MELT WILL BE AND THE MORE OF A PROBLEM ANY MODERATE TO HEAVY RAIN THAT FALLS WILL POSE THURSDAY. TEMPS LOOK TO CLIMB SAFELY ABOVE FREEZING THURS AM EVEN NORTH TO THE WI BORDER ENDING THE FRZ RAIN THREAT...BUT WITH PWATS PROGGED TO CLIMB TO OVER AN INCH (200-250% OF NORMAL) THURSDAY THE POTENTIAL WILL EXIST FOR HEAVY RAINFALL. HAVE ALREADY BEEN HARPING ON ALL THE HYDRO CONCERNS IN THE ESF ISSUED FRIDAY AND UPDATED OVER THE WEEKEND AND REALLY NO BIG CHANGES IN THINKING AT THIS POINT OTHER THAN TO SAY THE FLOOD POTENTIAL IS LOOKING MORE OMINOUS THAN IT DID 24 HOURS AGO. STRONG COLD FRONT LOOKS TO SWEEP THROUGH THURSDAY EVENING BRINGING AN END TO THE RAIN AND POSSIBLE THUNDERSTORMS AND ALLOWING DRIER AND COLDER AIR TO FILTER INTO THE REGION. WHILE COLDER AIR FILTERS IN FOR THE WEEKEND WITH MEDIUM RANGE MODELS SUGGESTING ONE OR TWO SYSTEM COULD AFFECT THE REGION WITH WHAT WOULD PROBABLY BE SOME SNOWFALL. TIMING AND TRACK OF THESE LOWER AMPLITUDE WAVES ARE ALL OVER THE PLACE IN THE MODELS SO ONLY CARRYING LOW CHANCES POPS FOR NOW. IZZI && .HYDROLOGY... 330 AM CST LATEST MODEL GUIDANCE DOES LOOK MORE WORRISOME THAN IT DID 24 HOURS AGO REGARDING THE FLOOD POTENTIAL THURSDAY...POSSIBLY LINGERING INTO THE WEEKEND. MORE DETAIL METEOROLOGICAL DISCUSSION IS ABOVE. NO CHANGES REALLY TO THE PREVIOUS HYDROLOGICAL DISCUSSION OTHER THAN SLIGHTLY MORE SNOW AND SNOW WATER EQUIVALENT IS EXPECTED TO BE IN PLACE AFTER TODAY`S SNOW SYSTEM. WILL FRESHEN UP THE ESF AGAIN THIS MORNING BUT NOT PLANNING ANY BIG CHANGES. && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * SLIGHT CHANCE FOR SNOW SHOWERS DURING THE MORNING * HEAVY SNOW TO DEVELOP EARLY AFTERNOON WITH OCNL VSBY BETWEEN 1/16SM AND 1/4SM EXPECTED * SLIGHT CHANCE OF THUNDERSTORM (THUNDERSNOW) IN THE AFTERNOON * STRONG SOUTHEAST WINDS DEVELOP DURING MORNING WITH GUSTS TO AROUND 25KT EXPECTED...DIMINISHING AS HEAVY SNOW STARTS * QUICK IMPROVEMENT AS SNOW ENDS EARLY MONDAY EVENING IZZI //DISCUSSION...UPDATED 06Z... LAKE EFFECT MVFR CIGS LIKELY TO PERSIST FOR AT LEAST A FEW MORE HOURS OVERNIGHT BEFORE PROBABLY BREAKING UP LATE. CONTINUE TO SEE SOME MODELS STARTING UP SNOW SHOWERS DURING THE MORNING HOURS MONDAY...WHICH IF IT WERE TO HAPPEN COULD RESULT IN A MUCH EARLIER ONSET TO IFR CONDITIONS THAN INDICATED IN THE CURRENT TAFS. HANDLING THIS WITH A VCSH IN THE TAFS AND WILL MONITOR RADAR/SATELLITE TRENDS THIS MORNING AND RE-ACCESS LATER. STRONG PRESSURE FALLS TO OUR WEST IN RESPONSE TO THE DEVELOPING LOW WILL RESULT IN A QUICK RAMP UP OF SOUTHEAST WINDS EARLY MONDAY MORNING WITH GUSTS OF 25-30KT EXPECTED BY MID-LATE MORNING. BIG STORY WILL BE THE INTENSE SNOW EXPECTED TO DEVELOP MONDAY AFTERNOON. ALL INDICATIONS ARE THAT 3 TO 6 HOUR LONG WINDOW OF MODERATE TO HEAVY SNOW WILL OCCUR MONDAY AFTERNOON. GETTING FAIRLY STRONG SIGNALS IN THE MODELS TO SUPPORT PERIODIC VERY HEAVY SNOWFALL WITH EVEN A SMALL CHANCE OF ISOLATED THUNDERSTORMS. WINDS WILL SUBSIDE AS SNOW BEGINS BUT WITH SNOWFALL RATES OF AT LEAST AN INCH PER HOUR LIKELY AND CRIPPLING RATES OF 2"+ PER HOUR POSSIBLE THE DECREASING WINDS WILL BE A BIT OF A MOOT POINT. CONDITIONS ARE LIKELY TO QUICKLY IMPROVE AS THE TROUGH MOVES THROUGH EARLY MONDAY EVENING. WINDS WILL SHIFT TO WESTERLY AND THERE WILL PROBABLY BE SEVERAL HOURS OF LINGER MVFR CIGS INTO THE EVENING HOURS. IZZI //ORD AND MDW CONFIDENCE...UPDATED 06Z... * LOW CONFIDENCE IN SNOW POTENTIAL BETWEEN 13-18Z MONDAY * HIGH CONFIDENCE IN ONSET TIME OF MOD-HVY SNOW +/- AN HOUR OR TWO * MEDIUM CONFIDENCE IN OCNL VSBY 1/4SM OR LOWER WITH ACCUMULATION RATES OF 1"/HOUR OR GREATER * MEDIUM-HIGH CONFIDENCE ON END TIME OF SNOW MONDAY EVENING +/- AN HOUR OR TWO * HIGH CONFIDENCE IN REMAINDER OF FORECAST ELEMENTS IZZI //OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z... TUESDAY AND WEDNESDAY...PREDOMINANTLY VFR. THURSDAY...RAIN/FOG/IFR LIKELY. FZRA POSSIBLE IN THE MORNING. FRIDAY...VFR PROBABLE. SATURDAY...CHANCE OF RA OR SN. MDB && .MARINE... 324 AM CST HAVE HOISTED A GALE WARNING FOR A LARGE PORTION OF CENTRAL LAKE MICHIGAN FOR TODAY. THE DEEPER SFC LOW IN THE MODELS SHOULD RESULT IN A PERIOD OF SOUTHEAST GALES THIS MORNING INTO THE EARLY AFTERNOON BEFORE THE BAGGIER PRESSURE GRADIENT APPROACHES THE LAKE ASSOCIATED WITH THE INVERTED TROUGH NORTH OF THE LOW TRACKING ACROSS DOWNSTATE IL AND IN. BRIEF SHOT OF WESTERLY WINDS TONIGHT IN THE WAKE OF THE TROUGH AND DEPARTING LOW BEFORE SOUTHERLY WINDS BEGIN TO REALLY CRANK UP AGAIN ON TUESDAY AS ANOTHER STRONG LOW TRACK EAST ACROSS THE SOUTHERN CANADIAN PRAIRIES. COULD BE BORDERLINE SOUTHERLY GALES ON TUESDAY AFTERNOON AS WELL...BUT FOR NOW JUST STUCK WITH OCNL GALE WORDING IN THE GLF AND WILL LET NEXT SHIFT GET ANOTHER LOOK BEFORE DECIDING ON POSSIBLE GALE HEADLINES FOR TUESDAY. IZZI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011- ILZ012-ILZ019-ILZ020-ILZ021-ILZ032-ILZ039 UNTIL 6 PM MONDAY. WINTER STORM WARNING...ILZ006-ILZ013-ILZ014-ILZ022-ILZ023- ILZ033...9 AM MONDAY TO 9 PM MONDAY. IN...WINTER STORM WARNING...INZ001-INZ002-INZ010-INZ011-INZ019...9 AM MONDAY TO 9 PM MONDAY. LM...GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ868-LMZ870-LMZ872-LMZ874-LMZ876...8 AM MONDAY TO 3 PM MONDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 PM MONDAY. && $$ 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...CORRECTION
NWS NORTHERN INDIANA
345 AM EST MON FEB 17 2014 .SYNOPSIS... ISSUED AT 343 PM EST MON FEB 17 2014 A LOW PRESSURE SYSTEM OVER THE PLAINS WILL MOVE EAST THROUGH INDIANA THIS AFTERNOON AND EVENING...CAUSING A BAND OF MODERATE TO HEAVY SNOW TO PIVOT THROUGH THE AREA DURING THIS TIME. SOME SLEET AND FREEZING RAIN MAY MIX WITH THE SNOW ALONG AND SOUTH OF HIGHWAY 24 IN INDIANA AND OHIO. TOTAL SNOW ACCUMULATIONS ARE FORECAST TO RANGE BETWEEN 2 AND 6 INCHES ACROSS THE FORECAST AREA...HEAVIEST ACROSS NORTHERN AREAS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 343 AM EST MON FEB 17 2014 BURST OF MOD-HVY SNOW THIS AFTN/EVE / MIXED WITH SLEET SOUTH OF HWY 24 / THE PRIMARY FOCUS THIS PERIOD... MORNING WATER VAPOR IMAGERY SHOWS A WELL DEFINED PV ANOMALY NEAR THE NE/CO BORDER WITH ANOTHER NORTHERN STREAM UPPER WAVE EDGING TOWARD THE MT/ND BORDER. GUIDANCE NOW IN EXCELLENT AGREEMENT IN PHASING THESE WAVES AS THEY RIPPLE QUICKLY EAST WITH A CLOSED MID LVL CIRCULATION EVENTUALLY EMERGING OVER SOUTHERN LOWER MICHIGAN THIS EVENING. THIS STRONG UPPER TROUGH WILL SHIFT NEGATIVE AND DEEP WITH 1.5 PVU SFC NEAR 700 MB ONCE IT LIFTS INTO IL/IN LATER TODAY. ASSOCIATED DEEP PLUME OF UPWARD VERTICAL MOTION WITH VIGOROUS WAVE LOOKS TO LIFT ENE THROUGH THE LOCAL AREA LATER THIS AFTN/EVE WITH A 4-7 HOUR PERIOD OF ACCUMULATING SNOW ANTICIPATED. SNOWFALL RATES OF 1-2" PER HR POSSIBLE GIVEN VERY STRONG DYNAMICS AND LOW LEVEL MOISTURE TRANSPORT/CONVERGENCE WITHIN DEVELOPING TROWAL AS SFC REFLECTION DEEPENS NORTHEAST INTO NRN INDIANA/SE MI. XSECTIONS/SOUNDINGS IMPRESSIVE WITH STEEP MID LVL LAPSE RATES INTO ESPECIALLY SOUTHERN AREAS ALONG WITH A THIN LAYER WHERE THETA-E DECREASES WITH HEIGHT. GIVEN THIS CANNOT RULE OUT SOME THUNDER BUT COVERAGE AND CONFIDENCE OF OCCURRENCE REMAINS TOO LOW TO INCLUDE A THUNDER MENTION IN GRIDS. NORTHERLY TRACK OF THIS PHASED SYSTEM WILL ALLOW SOME WARMER AIR ALOFT TO WORK INTO AREAS SOUTH/ALONG THE HWY 24 CORRIDOR WHERE PRECIP MAY MIX WITH SLEET (AND LOWER CHC FOR FREEZING RAIN FAR SOUTH) TO START BEFORE DYNAMIC/EVAPORATIVE COOLING OVERWHELMS SUPPORTING A CHANGEOVER TO ALL SNOW. THIS SHOULD CUT DOWN ON SNOW TOTAL A BIT HERE...WITH HEAVIEST TOTALS EXPECTED ACROSS THE FAR NORTH WHERE PIVOT IS EXPECTED UNDER DEVELOPING 700 MB LOW TRACK. CURRENT EXPECTATIONS ARE FOR A QUICK 4-6" (LOCALIZED 6" PLUS AMOUNTS POSSIBLE) OF SNOW NORTHWEST OF HWY 24...3-5" ALONG HWY 24...AND 2-4" SOUTHEAST OF HWY 24. STRONG RISE FALL COUPLET OVERSPREADS THIS EVENING INTO THE EARLY OVERNIGHT HOURS WHICH MAY CREATE SOME BLOWING/DRIFTING SNOW FOR A TIME. AS FOR THE NEAR TERM (THIS MORNING INTO EARLY AFTN)...6-8 MB SFC 3 HR PRESSURE FALLS WILL ALLOW WINDS TO PICK UP AND GUST TO BTW 25-30 MPH LATER THIS MORNING. THIS MAY LEAD TO SOME BLOWING AND DRIFTING IN RURAL/OPEN AREAS. CHANCES FOR SNOW INCREASE WITH TIME AS 850-700 MB THETA-E GRADIENT SHIFTS EAST INTO WESTERN AREAS THIS MORNING. BAND OF SNOW TRYING TO GET STARTED ALONG THIS GRADIENT ACROSS SOUTHERN WI/NORTHERN IL AS OF THIS WRITING BUT LOSING THE BATTLE TO DRY SUB-CLOUD LAYER AT THIS TIME. RAP SATURATES OVER THE AREA WITH RELATIVE NARROW OF SNOW DEVELOPING OVER WESTERN ZONES BTW 15-18Z WHILE THE 06Z NAM SLOWER AFTER 18Z. OPTED FOR CHC POPS GIVEN THE UNCERTAINTY. && .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 343 AM EST MON FEB 17 2014 FOR TUESDAY...QUIET WEATHER IN STORE WITH DEPARTURE OF MONDAYS SNOW PRODUCER...AS SHORT WAVE UPPER RIDGING TRACKS ACROSS THE GREAT LAKES. MID/UPPER LEVEL PATTERN TO BE QUITE PROGRESSIVE THROUGH MID WEEK AS LOWER AMPLITUDE WAVE TRACKS ACROSS NORTHERN PLAINS/NORTHERN GREAT LAKES EVENTUALLY ALLOWING SFC TROUGH/COLD FRONT PASSAGE INTO THE AREA TUESDAY NIGHT/EARLY WEDNESDAY MORNING. LOW LEVEL HEIGHT GRADIENT SHOULD STEADILY STRENGTHEN ON TUESDAY IN ADVANCE OF THIS TROUGH WHICH SHOULD ALLOW FOR SOUTH WINDS TO INCREASE BY MIDDAY. CURRENTLY EXPECTING GUSTS UP TO AROUND 25 MPH WHICH COULD CREATE SOME DRIFTING CONCERNS EARLY TUESDAY AFTERNOON ACROSS OPEN AREAS FOR ESPECIALLY EAST TO WEST ORIENTED ROADWAYS. RELATIVELY LOWER SNOW TO LIQUID RATIOS AND SFC TEMPS WARMING TO ABOVE FREEZING IN THE AFTERNOON SHOULD TEND TO MITIGATE THIS CONCERN HOWEVER. THE RELATIVELY DRY AIR MASS IN PLACE SHOULD LIMIT ANY MEASURABLE PRECIP CHANCES IN ASSOCIATION WITH THE FRONT TUESDAY NIGHT...ALTHOUGH GIVEN MOISTURE PROFILES AND WEAK LIFT CANNOT COMPLETELY RULE OUT SOME VERY LIGHT PATCHY FREEZING DRIZZLE FOR A BRIEF TIME IN IMMEDIATE VICINITY OF THE FRONT. WEAK THERMAL TROUGH WILL BE IN PLACE ACROSS THE AREA FOR WEDNESDAY BEHIND THIS FRONT...WITH EVENTUAL ONSET OF STRONGER LOW LEVEL WAA AGAIN TOWARD WEDNESDAY EVENING AS LOW LEVEL ANTICYCLONE SHIFTS TO THE MID ATLANTIC STATES. PRESENCE OF LOW LEVEL THERMAL TROUGH AND VERY SHALLOW MIXED LAYER DEPTHS SHOULD RESULT IN HIGHS A DEGREE OR TWO LOWER THAN TUESDAY AFTERNOON...ALTHOUGH STILL INTO AT LEAST MID 30S MOST LOCATIONS. WITH DAYTIME TEMPS MARGINALLY ABOVE FREEZING AND NIGHTTIME TEMPS EXPECTED TO DROP BELOW FREEZING TUESDAY NIGHT/WEDNESDAY NIGHT...SNOWMELT WILL BE VERY GRADUAL AND NO SIGNIFICANT HYDROLOGIC IMPACTS ARE EXPECTED THROUGH MIDWEEK. CONCERN FOR THURSDAY WILL THEN SHIFT TO WARMING TREND AND POTENTIAL FOR SIGNIFICANT RAINFALL WHICH WILL LEAD TO INCREASED FLOOD POTENTIAL. BULK OF GUIDANCE HAS NOW SHIFTED BACK TO TREND OF SEVERAL DAYS AGO IN DEPICTING TWO DISTINCT EASTERN PACIFIC WAVES PHASING ACROSS THE UPPER MIDWEST/NORTHERN GREAT LAKES...AND PROMOTING STRONGER CYCLOGENESIS ACROSS THE WESTERN GREAT LAKES FOR THURSDAY. DETAILS STILL DIFFICULT TO PIN DOWN AT THIS POINT WITH HOW THESE WAVES WILL INTERACT AND EXTENT/TIMING OF LOW LEVEL DEEPENING...BUT HAVE SLIGHTLY TRENDED FORECAST TO THIS STRONGER EVOLUTION. STRONG LOW LEVEL THETAE ADVECTION/MOISTURE TRANSPORT TO RACE NORTHEASTWARD INTO THE LOCAL AREA BY THURSDAY MORNING WITH PTYPE CONCERNS LIKELY TO EXIST AT ONSET OF PRECIP. A BRIEF PERIOD OF -SN/-FZRA IS POSSIBLE THURSDAY MORNING BEFORE STRENGTH OF LOW LEVEL ADVECTION OVERWHELMS PROFILES AND SUPPORTS LIQUID PRECIP TYPE. AFTER THIS INITIAL WARM/MOIST ADVECTIVE SURGE THURSDAY...ITEM OF LOWER CONFIDENCE WILL BE POTENTIAL FOR ANY ADDITIONAL PRECIP INTO THURSDAY EVENING THAT MAY HAVE SOME CONVECTIVE NATURE DEPENDING ON EXACT EVOLUTION OF PATTERN. THIS WILL NEED TO BE WATCHED FOR POTENTIAL HIGHER RAINFALL AMOUNTS THAT WILL IMPACT FLOOD POTENTIAL...ESPECIALLY IN LIGHT OF SFC DEW POINTS LIKELY RISING INTO THE UPPER 30S TO LOWER 40S THAT WILL ACCELERATE SNOWMELT. LARGER SCALE FRONTAL FORCING MAY ALLOW RAIN TO PERSIST THROUGH MUCH OF THURSDAY NIGHT...ESPECIALLY ACROSS EASTERN HALF OF THE AREA. COLDER AIR TO ADVECT BACK INTO THE REGION FOR FRIDAY BEHIND THIS SYSTEM THAT MAY PROVIDE SOME BENEFIT TO RUNOFF FROM RECENT RAIN/MELTING SNOW. WILL CONTINUE WITH ESF THIS MORNING HIGHLIGHTING OVERALL POTENTIAL...BUT MUCH OF THIS WILL DEPEND ON EXACT RAINFALL AMOUNTS THURSDAY ALONG WITH HOW QUICKLY UPSTREAM SYSTEM PHASES WHICH WILL BE CRITICAL FOR TEMP/DEW PT TRENDS. PREDICTABILITY IN SMALLER SCALE WAVES IMPACTING THE AREA FOR THE WEEKEND STILL QUITE LOW AT THIS TIME...ALTHOUGH NEW 00Z GUIDANCE STILL SUPPORTS IDEA OF DEEPER MOISTURE SHUNTED WELL SOUTH OF THE AREA. HAVE CONTINUED PREVIOUS LOW CHANCE -SN/RA POPS FOR THE WEEKEND WITH A SERIES OF LOW LEVEL AMPLITUDE CLIPPER SYSTEMS POSSIBLE THROUGH THE EARLY PORTIONS OF NEXT WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1229 AM EST MON FEB 17 2014 SATELLITE AND OBSERVATION TRENDS SHOW MVFR STRATO CU DECK ERODING AND SINKING SOUTH AS OF THIS WRITING. LIGHT EASTERLY WINDS AND INCREASING HIGH LEVEL CLOUDS SHOULD BE ENOUGH TO PRECLUDE SIGNIFICANT VIS RESTRICTIONS AT THE THERMIANALS THIS MORNING. ATTENTION THIS AFTN/EVE WILL TURN TO TIMING OF 4-6 HR PERIOD OF MODERATE/HEAVY SNOW AS VERY DYNAMIC/STRONG UPPER LEVEL SYSTEM LIFTS INTO THE AREA. LATEST GUIDANCE HAS TRENDED A LITTLE SLOWER WITH THIS INCORPORATED INTO 06Z TAFS. OTHERWISE...IMPRESSIVE PRESSURE FALLS TODAY WILL RESULT IN A BREEZY DAY WITH SHALLOW MIXING GENERALLY HOLDING GUSTS TO LESS THAN 30 KNOTS BEFORE DIMINISHING LATE AFTN/EARLY EVE AS SFC LOW CENTER TRACKS INTO NORTHERN INDIANA. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM EST TUESDAY FOR INZ006>009-017-018-025>027-032>034. WINTER WEATHER ADVISORY FROM NOON EST /11 AM CST/ TODAY TO 11 PM EST /10 PM CST/ THIS EVENING FOR INZ003>005-012>016-020- 022>024. MI...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM EST TUESDAY FOR MIZ079>081. WINTER WEATHER ADVISORY FROM NOON TODAY TO 11 PM EST THIS EVENING FOR MIZ077-078. OH...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM EST TUESDAY FOR OHZ001-002-004-005-015-016-024-025. LM...NONE. && $$ SYNOPSIS...JT SHORT TERM...STEINWEDEL LONG TERM...MARSILI AVIATION...STEINWEDEL VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS GOODLAND KS
937 PM MST SUN FEB 16 2014 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 151 PM MST SUN FEB 16 2014 CONCERNS THROUGH TOMORROW WILL BE WINDS TONIGHT AND FIRE WEATHER ISSUES MONDAY. COLD FRONT WILL MOVE THROUGH THE AREA DURING THE LATE EVENING AND OVERNIGHT HOURS. TIGHTENING PRESSURE GRADIENT AND 3 HOUR PRESSURE RISES BEHIND THE FRONT INDICATE THAT WINDS WILL BE NEAR WIND ADVISORY CRITERIA. MODELS INDICATE THAT WINDS AT 850 MB WILL BE IN THE 40 TO 50 KNOT RANGE. PROBLEM IS THAT LOW LEVEL LAPSE RATES ARE POOR DUE TO DECOUPLING FROM THE SURFACE. SOUNDINGS SHOW THE LOW LEVEL INVERSION REMAINING INTACT. ALSO STRONGEST DOWNWARD MOTION OCCURS AFTER THE STRONGEST LOW LEVEL WINDS HAVE MOVED OFF TO THE EAST. ALSO SINCE DO NOT THINK THERE WILL BE ANY PRECIPITATION AROUND...THE HIGHER WINDS SHOULD NOT BE MIXED DOWN TO THE GROUND. SO DO NOT PLAN ON ISSUING A WIND ADVISORY BUT WOULD NOT BE SURPRISED THAT WE COULD SEE GUSTS TO NEAR 45 MPH RIGHT AFTER THE FRONTAL PASSAGE. NOT A LOT OF COLD AIR BEHIND THIS FRONT. THAT COMBINED WITH A STRONG DOWNSLOPE COMPONENT TO THE WINDS SLOWING DOWN THE COOLING...LOW TEMPERATURES SHOULD STAY RATHER MILD AND MAY STAY ABOVE FREEZING IN SOME LOCATIONS. SHOULD SEE PLENTY OF SUN ON MONDAY. SURFACE RIDGE WILL MOVE TO THE SOUTH OF THE AREA BY LATE MORNING WITH A NEW LEE TROUGH DEVELOPING TO OUR WEST. WINDS WILL SHIFT FROM WEST TO NORTHWEST IN THE MORNING TO SOUTH AND SOUTHWEST IN THE AFTERNOON. MODELS DO NOT COMPLETELY GET RID OF LOW LEVEL INVERSION. HOWEVER WITH ONLY WEAK COOLING AND DOWNSLOPE COMPONENT TO THE WIND...TEMPERATURES MAY END UP BEING WARMER THAN TODAYS MAXES. DID RAISE MAXES A LITTLE BASED ON THE DRY AIR MASS...850 MB TEMPERATURES...AND A BLEND OF THE BETTER PERFORMING GUIDANCE FROM THE LAST FEW DAYS. REFER TO THE FIRE WEATHER SECTION FOR HOW THIS ALL AFFECTS FIRE WEATHER ISSUES. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 146 PM MST SUN FEB 16 2014 THE WARM DRY PATTERN WILL CONTINUE THROUGH WEDNESDAY AS A DRY ENVIRONMENT WILL PERSIST OVER THE AREA. A SURFACE TROUGH OF LOW PRESSURE WILL MOVE THROUGH THE AREA LATE MONDAY NIGHT THROUGH EARLY TUESDAY MORNING. BEHIND THE TROUGH WINDS WILL BECOME BREEZY EAST OF THE COLORADO BORDER TUESDAY AFTERNOON. WEDNESDAY A SHORT WAVE RIDGE WILL BUILD OVER THE AREA. WEDNESDAY NIGHT AN UPPER LEVEL TROUGH AND ASSOCIATED COLD FRONT WILL MOVE THROUGH THE AREA. THE ENVIRONMENT CONTINUES TO LOOK UNFAVORABLE FOR PRECIP. DEVELOPMENT AS THE MAIN UPPER LEVEL LOW OVER THE NORTHERN PLAINS BRINGS A DRY SLOT OVER THE TRI-STATE AREA AHEAD OF THE TROUGH. WITH THE ADDED LIFT OF THE FRONTAL PASSAGE THERE MAY BE ENOUGH LIFT TO GENERATE SOME PRECIP. FROM THE SHALLOW SATURATED LAYER. DRY CONDITIONS AND SLIGHTLY COOLER TEMPERATURES MOVE OVER THE AREA THURSDAY INTO FRIDAY AS ZONAL FLOW FOLLOWS THE TROUGH FROM WEDNESDAY NIGHT. FRIDAY NIGHT ANOTHER UPPER LEVEL TROUGH WILL MOVE ACROSS THE AREA BRINGING A STRONGER COLD FRONT WITH IT. MODELS HAVE FLATTENED THE TROUGH OUT CONSIDERABLY FROM YESTERDAY WHICH IN TURN HAS SHOVED THE DEEPER MOISTURE FURTHER NORTHEAST. AS A RESULT PRECIP. CHANCES HAVE DROPPED...WITH DRY CONDITIONS FORECAST FOR MUCH OF THE AREA FOR FRIDAY NIGHT THROUGH SATURDAY NIGHT. TEMPERATURES BEHIND THE FRONT WILL BE 10 TO 15 DEGREES BELOW NORMAL. SUNDAY A WARM FRONT MOVES THROUGH THE AREA BRINGING TEMPERATURES BACK TO NORMAL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 928 PM MST SUN FEB 16 2014 VFR CONDITIONS WILL CONTINUE THROUGH THE TAF PERIOD. THE COLD FRONT HAS ALREADY MOVED THROUGH KGLD AND WINDS HAVE SHIFTED TO THE NORTHWEST...A LITTLE EARLIER THAN PREVIOUSLY THOUGHT. THE COLD FRONT WILL HAVE MOVED THROUGH KMCK BEFORE 06Z WITH NORTHWEST WINDS AROUND 15 KTS AFTER BRIEFLY HIGHER WIND SPEEDS AND GUSTS. BASED ON OBSERVATIONS AT KGLD AND UPSTREAM...DID NOT INCLUDE GUSTS IN FOR THE INITIAL PREVAILING GROUP AT EITHER TERMINAL. HOWEVER...BUFKIT RAP SOUNDINGS STILL INDICATE WINDS INCREASING OVERNIGHT WITH GUSTS AROUND 30 TO 35 KTS BETWEEN 06Z AND 12Z. SINCE THE RAP SEEMS TO BE CATCHING THE CURRENT CONDITIONS AND UPSTREAM SITES HAVE GUSTS AROUND 35 KTS...DECIDED TO GO WITH THIS FOR NOW. TOMORROW AFTERNOON WINDS WILL SHIFT AGAIN TO THE WEST- SOUTHWEST...WITH GUSTS AROUND 20 TO 25 KTS. WINDS SHOULD DIMINISH AROUND SUNSET...REMAINING SUSTAINED AROUND OR UNDER 10 KTS WITH NO GUSTS. && .FIRE WEATHER... ISSUED AT 151 PM MST SUN FEB 16 2014 MUCH OF THE AREA WILL SEE RELATIVE HUMIDITIES OF 20 PERCENT OR SLIGHTLY LESS. QUESTION WILL BE THE WINDS. BELIEVE MODELS ARE OVERDOING WINDS FOR THE FOLLOWING REASONS. SURFACE RIDGE WILL HAVE NOT MOVED AWAY TOO FAR PLUS CROSS MOUNTAIN COMPONENT IS NOT THE GREATEST TO ALLOW A QUICK AND STRONG DEVELOPMENT OF A LEE TROUGH. ALSO THERE IS LITTLE TO NO DOWNWARD MOTION. IN FACT ANOTHER SHORTWAVE TROUGH WILL BE MOVING THROUGH. LOW LEVEL LAPSE RATES ARE NOT VERY GOOD AND THAT COMBINED WITH THE LACK OF DOWNWARD MOTION...MAKES ME THINK THAT MODELS ARE OVERDOING THE MIXING. HAD CONSIDERED A FIRE WEATHER WATCH FOR THE SOUTHWEST PORTION WHERE THE BEST COMBINATION OF WINDS AND RELATIVE HUMIDITIES WERE. HOWEVER AS SPECIFIED ABOVE...BELIEVE WILL NOT HAVE STRONG ENOUGH WINDS AND DO NOT BELIEVE RED FLAG CONDITIONS WILL BE MET FOR THREE HOURS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...BULLER LONG TERM...JTL AVIATION...ALW FIRE WEATHER...BULLER
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1252 AM EST MON FEB 17 2014 .UPDATE... ISSUED AT 905 PM EST SUN FEB 16 2014 TEMPERATURES ARE CRASHING THIS EVENING...ALREADY -8F AT THE OFFICE HERE IN NEGAUNEE TWP. ALTHOUGH HIGHER CLOUDS ARE MOVING INTO THE AREA FROM THE WEST...IT WILL TAKE AWHILE FOR THEM TO REACH THE EASTERN HALF OF THE FORECAST AREA. AS SUCH...LOWERED TEMPERATURES ACROSS THE ENTIRE AREA. IN FACT...WOULD NOT BE SURPRISED TO SEE TEMPS -20F ACROSS THE EAST TONIGHT. WITH THE CLOUDS MOVING INTO THE WEST...TEMPS SHOULD LEVEL OUT THERE...BUT STILL CLOSE TO ZERO OR A LITTLE BELOW. OTHERWISE...LOTS OF RADAR RETURNS IN MN...BUT IT LOOKS LIKE MOST OF IT IS VIRGA AS THERE ARE NOT MANY SFC REPORTS OF SNOW UNTIL YOU GET MUCH CLOSER TO THE FRONT IN THE DAKOTAS. COULD SEE SOME LIGHT SNOW TIED TO THE FIRST PUNCH OF WARM ADVECTION MOVING NORTHWARD LATE TONIGHT...BUT THE THOUGHT IS THAT THE BEST SNOW WILL NOT MOVE INTO THE WEST UNTIL AFT 12Z. AS SUCH...WILL LOWER POPS TONIGHT INTO EARLY MON MORNING ESPECIALLY ACROSS THE CENTRAL PART OF THE FORECAST AREA. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 418 PM EST SUN FEB 16 2014 WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL PATTERN ACROSS THE WEST AND CNTRL CONUS WITH A MID/UPPER LEVEL TROUGH AND SEVERAL EMBEDDED SHRTWVS THROUGH THE NRN ROCKIES. LINGERING CONFLUENT FLOW OVER NRN ONTARIO INTO THE NRN LAKES AND ASSOCIATED SFC ARCTIC HIGH PRESSURE HAS BROUGHT MOSTLY CLEAR SKIES TO THE REGION. VIS LOOP SHOWED MID/HIGH CLOUD SPREADING QUICKLY THROUGH MN WITH THE WAA REGIME AHEAD OF LOW PRES OVER THE WRN PLAINS. TONIGHT...CLEAR SKIES EARLY THIS EVENING SHOULD GIVE WAY TO INCREASING CLOUDS OVERNIGHT...PER MDLS RH FCST AND SATELLITE TRENDS. RADIATIONAL COOLING THIS EVENING WILL ALLOW TEMPS TO DROP QUICKLY WITH GRADUALLY RISING TEMPS OVERNIGHT FROM WEST TO EAST. OVER THE ERN CWA...WITH THE LONGER PERIOD OF CLEAR SKIES...TEMPS COULD DROP TO AROUND -10F OR EVENING COLDER. OTHERWISE...LOWS IN THE ZERO TO -5F RANGE ARE EXPECTED CENTRAL AND 0 TO 5F WEST. MONDAY...THE MODELS WERE IN RELATIVELY GOOD AGREEMENT AS THE MID LEVEL TROUGH MOVES THROUGH THE UPPER MS VALLEY AND GREAT LAKES. THE STRONGER 700-300 MB QVECTOR CONV ASSOCIATED WITH THE THE SRN SHRTWV WILL IS EXPECTED TO MOVE THROUGH SRN WI INTO SRN LOWER MI. HOWEVER...THE WEAKER QG FORCING TO THE NORTH ALONG WITH 285K-290K ISENTROPIC LIFT AHEAD OF THE TROUGH WITH 2G/KG AVAILABLE SHOULD ALSO SUPPORT MODERATE SNOWFALL ACROSS UPPER MICHIGAN. WITH THE STRONGER DYNAMICS TO THE SOUTH OF THE CWA...THE FCST LEANED MORE TOWARD THE LOWER END OF CONSENSUS QPF VALUES...MAINLY IN THE 0.25 TO 0.35 INCH RANGE...PER NAM AND REGIONAL GEM. UPWARD MOTION THE DGZ SUPPORTS SLR VALUES IN THE 15/1 TO 20/1 RANGE GIVING OVERALL SNOWFALL AMOUNTS IN THE 3 TO 6 INCH RANGE. ALTHOUGH SRLY WINDS WILL INCREASE AND BECOME GUSTY AT TIMES...BLSN IS NOT EXPECTED TO BE A SIGNIFICANT PROBLEM. A WINTER WEATHER ADVISORY WAS ISSUED TO COVER THE EXPECTED CONDITIONS. THE BEST CHANCE TO REACH OR EXCEED THE 6 INCH WARNING THRESHOLD WOULD BE OVER THE SRN CWA...BUT CONFIDENCE WAS NOT HIGH ENOUGH TO POST A WINTER STORM WARNING. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 335 PM EST SUN FEB 16 2014 A SHORTWAVE TROUGH WILL BE OVER WRN UPPER MI AT 00Z TUE AND WILL PUSH E OF THE CWA SHORTLY AFTER 06Z TUE. MOST OF THE SNOW FROM THIS SYSTEM COMES PRIOR TO 00Z TUE...SO WILL LEAVE MOST OF THE DISCUSSION OF THIS SYSTEM TO THE SHORT TERM FORECASTER. 12Z/16 GFS CONTINUES TO APPEAR TOO FAST WITH THE SYSTEM...SO STUCK WITH NON-GFS SOLUTIONS FOR POPS/QPF. MOST OF THE ADDITIONAL SNOW MON NIGHT FALLS PRIOR TO 06Z...WITH NO SNOW EXPECTED IN THE 00Z-06Z TIME PERIOD OVER FAR WRN UPPER MI TO 2 INCHES OVER THE ERN CWA. DEEP MOISTURE EXITS WITH THE SHORTWAVE LATE MON NIGHT WHILE MID/LOW LEVEL TEMPS INCREASE AS THE MID LEVEL PORTION OF A WARM FRONT MOVES IN FROM THE W. THIS TRAPS MOISTURE IN THE LOW LEVELS OVER THE ERN CWA WITH DRY AIR ABOVE THE INVERSION...WHICH LEAVES THE DGZ DRY AND SUB-INVERSION TEMPS NOT SUFFICIENT FOR ICE CRYSTAL FORMATION. THINK THERE IS A POSSIBILITY OF FREEZING DRIZZLE OVER ERN UPPER MI FOR A BRIEF PERIOD LATE MON NIGHT INTO TUE MORNING AS THE SFC PORTION OF THE WARM FRONT APPROACHES. THE CENTRAL AND WRN CWA WILL NOT SEE AS MUCH MOISTURE UNDER THE INVERSION...SO NOT AS WORRIED THERE. HOWEVER...GIVEN LACK OF SIGNIFICANT TOPOGRAPHY FOR UPSLOPE WITH THE SW WINDS OVER SCHOOLCRAFT AND LUCE COUNTIES...WILL NOT ADD FREEZING DRIZZLE TO THE FORECAST AT THIS TIME. THE REST OF TUE IS TRICKY...ESPECIALLY WITH TEMPERATURES POSSIBLY APPROACHING FREEZING FOR THE FIRST TIME IN A WHILE. A THERMAL RIDGE PASSES OVERHEAD AROUND MID DAY TUE WITH 850MB TEMPS AOA 0C IN MOST LOCATIONS...WHICH IS FAVORABLE FOR WARMER TEMPS. NEGATIVES FOR THE WARMER TEMPS ARE EASIER TO COME UP WITH...INCLUDING THE FACT THAT IT HAS BEEN QUITE COLD LATELY SO THE SNOW PACK IS VERY COLD. WE WILL HAVE FRESH SNOW FROM THE PREVIOUS EVENING THAT WILL HELP KEEP TEMPS COLD AND SFC ALBEDO LOWER. ANY WARMING POTENTIAL FROM THE NORMAL WARMER WATERS OF THE GREAT LAKES WILL BE REDUCED OR ELIMINATED DUE TO ICE COVER. UNTIL THE WARM FRONT MOVES THROUGH...THERE SHOULD BE A GOOD AMOUNT OF CLOUD COVER...WHICH WILL LIMIT WARMING. A COLD FRONT MOVES INTO THE CWA LATE TUE AFTERNOON AND TUE EVENING...BRINGING COLDER AIR AND MORE CLOUDS. IN FACT...BY 00Z WED...NWRN UPPER MI SHOULD SEE 850MB TEMPS DOWN TO -4C. ANOTHER SIGNIFICANT NEGATIVE FOR THE WARMER TEMPS IS THAT MODELS ARE SHOWING A COUPLE OF WEAK SHORTWAVES MOVING ACROSS THE NRN CWA FROM EARLY TUE AFTERNOON THROUGH TUE EVENING...WHICH WILL AT LEAST KEEP CLOUD COVER UP OVER NRN UPPER MI AND LAKE SUPERIOR AND MAY EVEN BRING SOME MINOR LIGHT SNOW /SINCE AREAS OF THE LOW AND MID LEVELS THAT WILL BE ABOVE 0C WILL BE DRY WITH SUB-ZERO WET BULB TEMPS/. CONSIDERING ALL THIS...TEMPS WILL BE VERY CONDITIONAL...WITH THE BEST CHANCES OF SEEING ABOVE FREEZING TEMPS OVER SRN UPPER MI NEAR THE WI BORDER. LEFT TEMPS SIMILAR ALONG THE WI BORDER...BUT LOWERED A COUPLE OF DEGREES OVER NRN AREAS. NO SIGNIFICANT PRECIP IS EXPECTED WED AND TEMPS WILL BE BELOW FREEZING AS MODELS CONTINUE TO INDICATE 850MB TEMPS AOB -5C AT 18Z. ANOTHER THERMAL RIDGE MOVES THROUGH WED NIGHT. A SHORTWAVE LOOKS TO MOVE INTO THE REGION LATER THU INTO THU NIGHT...BRINGING COLDER AIR FOR THE REST OF THU ALONG WITH INCREASED CLOUD COVER. AS FAR AS PRECIP IS CONCERNED...THINGS ARE A LOT MORE UNCERTAIN AS MODELS DO NOT HAVE GOOD CONTINUITY WITH THE EXACT LOCATION AND INTENSITY OF THE SHORTWAVE. AT THIS TIME...IT DOES APPEAR THE BULK OF THE SHORTWAVE ENERGY WILL GO N OF THE CWA...WITH POSSIBLY ADVISORY LEVEL SNOWFALL OVER UPPER MI. AGAIN...UNCERTAINTY IS HIGH IN THE PRECIP FORECAST FOR THIS TIME PERIOD. THEN FOR FRI THROUGH NEXT SUN...IT APPEARS THAT UPPER TROUGHING WILL DOMINATE MUCH OF THE CONUS...BRINGING A RETURN OF BELOW NORMAL TEMPERATURES. WHILE THERE IS MORE CONFIDENCE IN THE COLDER TEMPS...OVERALL CONFIDENCE IS LOW. USED GENERAL MODEL CONSENSUS FOR THIS PERIOD OF THE FORECAST. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1251 AM EST MON FEB 17 2014 A LOW PRESSURE SYSTEM OVER THE PLAINS WILL MOVE TOWARD THE AREA...SPREADING SNOW INTO UPPER MICHIGAN ON MONDAY. EXPECT VFR CONDITIONS TONIGHT TO RAPIDLY GIVE WAY TO IFR CONDITIONS MONDAY MORNING AT IWD AND CMX...AND PERHAPS WAITING UNTIL LATE MORNING SAW. COULD SEE SOME PERIODS OF LIFR VSBYS/CIGS AND SAW AND CMX DURING THE AFTERNOON HOURS BEFORE ALL SITES IMPROVE TO MVFR MONDAY EVENING. IN ADDITION TO THE SNOW...A LOW LEVEL JET WILL DEVELOP OVER THE AREA LATE TONIGHT INTO MONDAY MORNING. THIS SHOULD ALLOW LLWS TO DEVELOP LATE TONIGHT AND CONTINUE THROUGH THE MORNING HOURS. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 418 PM EST SUN FEB 16 2014 OVERALL...WINDS ARE FORECAST TO BE LESS THAN 25 KTS THROUGH THE UPCOMING WEEK. SOUTHEAST WINDS TO 30 KTS OCCUR MONDAY AND MONDAY EVENING OVER EASTERN AND NORTH CENTRAL LK SUPERIOR...BUT GALES ARE NOT EXPECTED AS MAIN SFC LOW PRESSURE PASSES OVER CNTRL AND LOWER GREAT LAKES. WINDS MAY TREND STRONGER LATE THIS WEEK AS ANOTHER LOW PRESSURE SYSTEM IMPACTS THE REGION. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 11 AM THIS MORNING TO 1 AM EST TUESDAY FOR MIZ006-007-014-085. WINTER WEATHER ADVISORY FROM 7 AM EST /6 AM CST/ THIS MORNING TO 10 PM EST /9 PM CST/ THIS EVENING FOR MIZ001-003>005- 010>013-084. WINTER WEATHER ADVISORY FROM 5 AM EST /4 AM CST/ EARLY THIS MORNING TO 7 PM EST /6 PM CST/ THIS EVENING FOR MIZ002-009. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...MRD SHORT TERM...JLB LONG TERM...TITUS AVIATION...MRD MARINE...JLB
AREA FORECAST DISCUSSION
NWS DULUTH MN
1142 PM CST SUN FEB 16 2014 .UPDATE... ISSUED AT 710 PM CST SUN FEB 16 2014 GUSTY EAST WINDS TO 25 KT HAVE PRODUCED ENOUGH LIFT TO KICK OFF LOW CLOUDS AND FLURRIES ALONG THE NORTH SHORE AND WESTERN TIP OF LAKE SUPERIOR THIS EVENING. THIS EVENING SNOW WILL BE VERY LIGHT WITH NO ACCUMULATION. THE MAIN PERIOD OF ACCUMULATING SNOW WILL AROUND AROUND MIDNIGHT IN THE TWIN PORTS. HAVE INCREASED WINDS OVERNIGHT BASED ON LATEST NAM BUFR SOUNDINGS AND 23Z RUN OF HRRR SHOWING GUSTY SE WINDS AHEAD OF THE TROUGH. THE STRONGEST WINDS AND GUSTS TO 25 KT WILL BE FOUND ACROSS THE BRD LAKES REGION..EAST OVER THE ST CROIX RIVER VALLEY. DUE TO THE COMBO OF GUSTY WINDS AND FALLING SNOW...HAVE ALSO INTRODUCED AREAS OF BLOWING SNOW TO THE FCST. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 301 PM CST SUN FEB 16 2014 AT 300PM/2100Z...SURFACE HIGH PRESSURE WAS CENTERED OVER ONTARIO WITH ITS RIDGE AXIS STRETCHING SOUTH THROUGH THE NORTHLAND. THIS WAS PROVIDING THE NORTHLAND SUNNY TO MOSTLY SUNNY SKIES. HOWEVER...THERE WAS INCREASING CLOUD COVER WEST OF THE NORTHLAND AND ACROSS THE NORTHERN PLAINS AHEAD OF AN APPROACHING TROUGH/WARM FRONT STRETCHING FROM SOUTHERN ALBERTA AND THROUGH THE NORTHERN HIGH PLAINS IN EASTERN MONTANA AND WYOMING. THE EASTERN FORECAST AREA HAD VERY LIGHT TO CALM WIND...BUT THE WESTERN FORECAST AREA HAD INCREASING SE WINDS. THE TEMPERATURES RANGED FROM THE SINGLE DIGITS IN THE ARROWHEAD TO THE MID TO UPPER TEENS ACROSS THE REST OF THE FORECAST AREA. THE FOCUS FOR THIS FORECAST IS THE ROUND OF SNOW EXPECTED TO MOVE THROUGH THE NORTHLAND AFTER MIDNIGHT AND THROUGH MONDAY IN ADVANCE OF THE TROUGH/WARM FRONT WHICH WILL MOVE THROUGH THE NORTHLAND MONDAY. SOME MODELS INCREASED PCPN AMOUNTS FOR SOME AREAS...WHICH RESULTED IN INCREASING SNOWFALL AMOUNTS...SUCH AS FOR THE TWIN PORTS. WIDESPREAD SNOWFALL AMOUNTS AROUND 6 INCHES ARE EXPECTED FOR THE TWIN PORTS AREA AND ALONG THE INTERSTATE 35 CORRIDOR...AND CONSIDERING PERIODS OF HEAVY SNOWFALL RATES COULD MAKE FOR DIFFICULT DRIVING CONDITIONS FOR THE MORNING COMMUTE...I DECIDED TO EXPAND THE WINTER STORM WARNING TO THE SOUTH CENTRAL FORECAST AREA. SNOW WILL BEGIN TO SPREAD INTO NORTH CENTRAL AND CENTRAL MINNESOTA AROUND MIDNIGHT AS THE TROUGH/WARM FRONT MOVE INTO THE CENTRAL/EASTERN DAKOTAS AROUND THIS TIME. THE SNOW WILL QUICKLY SPREAD INTO NORTHEAST MINNESOTA AND NORTHWEST WISCONSIN AFTER MIDNIGHT AND MONDAY MORNING. THERE ARE STILL SOME DIFFERENCES IN MODEL PCPN AMOUNTS AND SLIGHTLY DIFFERENT TIMING. I LEANED ON A WIDE BLEND...BUT PERHAPS A LITTLE MORE TOWARDS THE SREF. THE MODELS...INCLUDING THE SREF...SUGGEST WIDESPREAD 4 TO 7 INCHES WITH THE HIGHEST AMOUNTS ACROSS THE CENTRAL AND EASTERN FORECAST AREA. DESPITE THE WARMER AIR WITH THIS SYSTEM...SEVERAL MODELS ARE SUGGESTING SNOW TO LIQUID RATIOS AROUND OR GREATER THAN 15 TO 1. THIS MAY IN PART DUE TO THE LIKELIHOOD OF SOME ENHANCED DEPTH AND LIFT IN THE DENDRITIC GROWTH ZONE...WHICH WILL HELP INCREASE THE SNOW TO LIQUID RATIOS. THE HIGHEST AMOUNTS OF SNOW WILL LIKELY BE ALONG THE NORTH SHORE...WHERE AMOUNTS COULD REACH UP TO 8 INCHES DUE TO A LITTLE LAKE ENHANCEMENT FROM SE TO E WINDS. GRANTED...THE LAKE IS FAIRLY ICE COVERED...BUT WE HAVE STILL BEEN SEEING SOME LAKE ENHANCEMENT AND LIGHT LAKE EFFECT SNOW RECENTLY. THE SNOW WILL BEGIN TO MOVE EAST OF THE NORTHLAND MONDAY AFTERNOON. HIGH TEMPERATURES WILL BE LIMITED TO THE LOW TO MID 20S ACROSS THE EASTERN FORECAST AREA...BUT PARTS OF THE WESTERN FORECAST WILL LIKELY SEE ABOVE FREEZING TEMPERATURES THANKS TO PARTIAL SUNSHINE IN THE MID TO LATE AFTERNOON. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 301 PM CST SUN FEB 16 2014 SIGNIFICANT SNOW SHOULD BE DIMINISHING RAPIDLY ACROSS THE EASTERN SECTIONS OF THE DULUTH CWA..OR ENDED ALTOGETHER..BY THE BEGINNING OF THE MONDAY NIGHT PERIOD. SECONDARY S/W TROF WILL ROTATE EASTWARD ACROSS THE NORTHLAND MONDAY NIGHT/TUE MORNING..WITH CONTINUED LOW LEVEL WARM ADVECTION IN OUR BRIEF EXCURSION INTO THE WARM SECTOR. THIS SHOULD BE SUFFICIENT TO SQUEEZE OUT SOME VERY LIGHT PRECIP. MOST LIKELY IN THE FORM OF SOME PATCHY LIGHT SNOW OVER THE FAR NORTH..BUT PROBABLY IN THE FORM OF FLURRIES OR SOME PATCHY LIGHT FREEZING DRIZZLE ALONG AND SOUTH OF THE HIGHWAY 2 CORRIDOR. OVERALL..NOT A MAJOR EVENT..BUT COULD BE ENOUGH TO PROLONG SLICK ROADS IN MANY AREAS IN THE WAKE OF MODERATE SNOWFALL TONIGHT AND MONDAY. WEAK COLD ADVECTION AND HIGH PRESSURE WILL THEN BUILD INTO THE REGION LATER TUESDAY/WEDNESDAY. HOWEVER..UNLIKE MOST OF THE LAST 2 MONTHS..THIS POST-FRONTAL AIRMASS WILL HAVE ITS SOURCE REGION IN THE DOWNSLOPE OF THE NORTHERN ROCKIES. AS A RESULT..TUE/WED SHOULD BE CONSIDERABLY WARMER ACROSS THE REGION..ESPECIALLY WITH THE STRONGER FEBRUARY SUN AND LONGER DAYS..WHICH WILL ALLOW INSOLATION TO INTERACT WITH THE LOWER ALBEDO OF THE FORESTED AREAS. WE HAVE RAISED MAX TEMPS SOME FROM THE PREVIOUS FORECAST FOR BOTH DAYS..AND SOME AREAS ON WED COULD PUSH 40 ACROSS NW WISCONSIN AND PARTS OF NE MN. NEXT RAPIDLY MOVING DISTURBANCE WILL MOVE ACROSS THE NORTHERN TIER OF STATES MID WEEK..AFFECTING THE NORTHLAND WED NIGHT/THUR. RIGHT NOW..MOST CURRENT MEDIUM RANGE GUIDANCE DEPICTS THE ORIENTATION AND DYNAMIC FORCING WITH THIS SYSTEM AS SIMILAR TO THE ONE FOR TONIGHT AND MONDAY..WITH A RAPID INCREASE IN STRONG UPWARD VERTICAL MOTION FIELDS DEVELOPING ACROSS MN LATER WED NIGHT/THUR MORNING. AIRMASS WILL NOT BE AS COLD..SO SNOW RATIOS WILL BE LOWER..AND SOME PRECIP COULD BE A MIX OR RAIN ACROSS THE FAR SOUTH DEPENDING ON THE EVENTUAL EVOLUTION OF THE WARM SECTOR. SO..SNOWFALL AMOUNTS MAY BE LESSER AND SNOW OF THE HEAVIER/WETTER VARIETY. HOWEVER..IT SHOULD BE NOTED THAT THE STRENGTH OF THE VERTICAL MOTION FIELDS AND RAPID DEVELOPMENT OF PRECIP WED NIGHT WOULD ARGUE FOR STRONG DYNAMIC AND DIABATIC COOLING OF THE LOWER PORTIONS OF THE ATMOSPHERE..AND THUS A MOSTLY SNOW SOLUTION. OF COURSE..THE ECM/GFS HAVE A HARDER TIME HANDLING THE NORTHWARD SURGE OF THE WARM AIR ALOFT..SO THE POTENTIAL FOR MIXED PRECIP OR RAIN SEEMS TO BE BACK ON THE TABLE A BIT MORE THAN THIS TIME YESTERDAY. PTYPE ISSUES SHOULD BECOME CLEARER WHEN THIS SYSTEM GETS INTO THE 84 HR FORECAST WINDOW OF THE WRF-BASED MODELS AND ENSEMBLE SYSTEMS THAT SEEM TO HANDLE THE RETURNING WARM LAYER IN STRONG WARM ADVECTION PATTERNS BETTER. FOR THE THUR-SAT TIME FRAME..MORE NORTHERLY COMPONENT TO THE FLOW ALOFT DEVELOPS ONCE AGAIN..WITH THE STORM TRACK RETREATING SOUTHWARD. AS A RESULT..PROGRESSIVELY COLDER AIR OF MORE ARCTIC ORIGIN SHOULD GRADUALLY BECOME ESTABLISHED ONCE AGAIN..ALONG WITH A FEW CHANCES FOR SOME LIGHT SNOW. ANOTHER STRONG PUSH OF VERY COLD ARCTIC AIR WITH 850 TEMPS AOB -25C LOOKS TO BE ON TAP FOR LATE NEXT WEEKEND AND THE BEGINNING OF THE WEEK OF FEB 24..JUST BEYOND THE RANGE OF THIS 7 DAY FORECAST WINDOW. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1145 PM CST SUN FEB 16 2014 GUSTY SOUTHEAST WINDS WILL PREVAIL OVERNIGHT AHEAD OF A STRONG FRONT. THE FRONT WILL SPREAD LOWERING CEILINGS AND SNOW ACROSS THE FORECAST AREA THROUGH DAYBREAK. THERE WILL BE A 4-6 HOUR WINDOW OF +SN WITH RAPID ACCUMULATIONS AND IFR/LIFR CIGS THROUGH MONDAY MORNING. PLEASE REFER TO THE LATEST WINTER WEATHER MESSAGE FOR MORE DETAILS ON SNOW AMOUNTS. AS THE FRONT TRANSLATES EAST ACROSS THE REGION MONDAY AFTERNOON...WINDS WILL TURN OUT OF THE WEST AND CONDITIONS WILL RAPIDLY IMPROVE. && .PRELIMINARY POINT TEMPS/POPS... DLH 4 25 18 37 / 100 100 10 20 INL 11 26 18 31 / 100 100 30 30 BRD 15 34 21 36 / 100 100 10 10 HYR 9 28 17 40 / 90 100 10 10 ASX -1 28 18 38 / 90 100 20 20 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WARNING UNTIL 6 PM CST MONDAY FOR MNZ012-020-021. WINTER WEATHER ADVISORY UNTIL NOON CST MONDAY FOR MNZ010-018-025- 026-033>036. WINTER STORM WARNING UNTIL 3 PM CST MONDAY FOR MNZ037-038. WINTER WEATHER ADVISORY UNTIL 3 PM CST MONDAY FOR MNZ011-019. WI...WINTER STORM WARNING UNTIL 3 PM CST MONDAY FOR WIZ001>004- 006>009. LS...NONE. && $$ AVIATION...GRANING
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
348 AM CST Mon Feb 17 2014 .DISCUSSION... Issued at 346 AM CST MON FEB 17 2014 Freezing rain is blossoming across central and northern MO early this morning in an area of deep isentropic ascent and increasing moisture. The freezing line has been able to lift a tad further north than what was forecast and currently stretches from just north of St. Joseph to near Chillicothe and just north of Boonville. Temperatures are expected to remain above freezing for the remainder of the day for areas south of this line so the freezing rain advisory will be adjusted to remove a few counties near St. Joe. Further north and east, concern is growing that ice totals may be a bit higher than previously forecast for the Kirksville, Milan and Macon areas. Both the RAP and HRRR have been persistent in producing QPF amounts around a half inch for these areas through mid-morning, most of which would fall as freezing rain. If these amounts were to verify, several counties across northern and northeast Missouri would see ice accumulations between a quarter of an inch and a half inch which would push them into ice storm warning criteria. However, both of these models have been initializing with precipitation too far west near Kansas City where radar echoes have been slow to develop. Isentropic ascent is currently maximized near and east of the US 65 corridor which is where most of the precipitation is, with only weak ascent if not downglide starting to push into western MO. This downglide is forecast to increase through the morning so that precipitation may struggle to intensify over western MO, causing the RAP and HRRR precipitation forecasts to be too high. Will therefore stick with ice totals of a quarter inch or less for northeastern portions of the forecast area. However this area will be watched very closely in case precipitation does expand further west and leads to more ice accumulation than what is currently forecast. Colder air will filter in aloft after 8 am and cause precipitation over northern MO to mix with sleet and snow. Snow and sleet accumulations up to an inch are possible mainly north of a Maryville to Kirksville line. Any sleet and snow should be fairly short lived as isentropic downglide will really increase after 15Z and bring precipitation to a rapid end by noon. The main story behind this system will be rising temperatures with westerly downslope flow bringing temperatures into the middle and upper 50s for most areas on Tuesday. The next weather maker will arrive Wednesday night and Thursday when a surface low will track from southern Kansas into central and northeast Missouri. Rain will overspread the area ahead of this system Wednesday night and Thursday morning and there could be a few thunderstorms near and south of the surface low track. Quasi-zonal upper flow behind this system will keep temperatures several degrees above average through Friday. Models continue to advertise a weak system moving into the area over the weekend with the potential for light wintry precipitation. Higher preference was placed on the more consistent GFS solution which would keep any precipitation amounts fairly light. && .AVIATION...(For the 06Z TAFS through 06Z Monday Night) Issued at 1156 PM CST SUN FEB 16 2014 Models have been a little too aggressive bringing low ceilings northward this evening, and feel this trend may continue. Ceilings will gradually fall into MVFR category towards 3am as low level lift increases. There will be a brief window where ceilings drop to IFR levels towards daybreak ahead of a weak surface trough. Scattered showers and or drizzle will work across the KC terminals through daybreak, but with temperatures already at or above freezing, the icing threat should be minimal. Ceilings should quickly rebound after this front moves through at 15Z, with VFR skies and gusty west northwest winds through the afternoon. At STJ, and across northern Missouri, slightly higher potential for light icing, with a brief changeover to snow at STJ after daybreak. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...FREEZING RAIN ADVISORY until Noon CST today FOR MOZ014-022>025- 032-033-040. WINTER WEATHER ADVISORY until Noon CST today FOR MOZ005>008- 015>017. FREEZING RAIN ADVISORY until 9 AM CST this morning FOR MOZ011>013. WINTER WEATHER ADVISORY until 9 AM CST this morning FOR MOZ001>004. && $$ DISCUSSION...Hawblitzel AVIATION...Dux
AREA FORECAST DISCUSSION
NWS SPRINGFIELD MO
1212 AM CST Mon Feb 17 2014 .UPDATE... Issued at 934 PM CST SUN FEB 16 2014 We have made some tweaks to PoPs overnight along with adding a slight chance for thunder across much of the area. The latest surface analysis indicates a warm front extending from central Kansas, south to around Stillwater, Oklahoma. This front then continues southeast to around Lake Eufaula in east-central Oklahoma. Dew points to the south of this front across Oklahoma have actually risen into the lower and middle 50s. North of the front across the Ozarks, dew points ranged from the middle 20s to lower 30s. 9 PM temperatures were still in the middle to upper 40s across southwestern Missouri. In contrast, temperatures around Rolla and Salem were in the lower to middle 30s. Later this evening and overnight, weak surface low pressure will develop across north-central Oklahoma as digging short wave energy emerges across the central Plains. This low will pull northeast towards Kansas City by around sunrise. The warm front will follow suit and push northeast into western Missouri. Ahead of this front, lift will rapidly increase in both the low levels (isentropic upglide owing to a 50 knot low level jet) and the upper levels. Rain showers are therefore expected to blossom and increase in coverage starting around 06 UTC or shortly thereafter. We have maintained high-end likely and categorical PoPs across central Missouri where low-level moisture transport and theta-e advection will be maximized. In contrast, we have slightly lowered PoPs overnight near the Arkansas border where low level lift will be weaker. We have also added a slight chance for thunder generally along and north of the Interstate 44 corridor late tonight. The last three runs of the RAP and to some extent the NAM have latched onto a slug of MUCAPEs in the 300-600 J/kg range with source parcels rooted in the 825-750 mb layer. As that digging wave approaches, a quick cooling of mid-level temperatures may also support some small hail/graupel from any thunderstorms or heavier showers. We are still concerned about the potential for some freezing rain late tonight as those showers develop and push into the eastern Ozarks. While southeasterly winds will increase and result in steady or slowly rising temperatures, we will also see wet-bulbing as precipitation falls into a relatively dry low-level air mass. At this time, the main area of concern is up across eastern Maries and Phelps Counties where shower coverage will be greatest and temperatures will be right around the freezing mark. We will also have to watch areas down towards Salem and Eminence if shower activity manages to develop farther south. && .SHORT TERM...(This Evening through Monday) Issued at 146 PM CST SUN FEB 16 2014 Another challenging and complex day of temperatures across the area today. Clouds and easterly winds have wreaked havoc, with temperatures barely moving in central Missouri with modest warming elsewhere. In the coming hours, should see some additional warming with readings varying from the mid 30s in central Missouri to the low/mid 50s across southern Missouri. The forecast gets even more complicated tonight and Monday. A potent shortwave will traverse the upper Midwest sending a front through the area. Southerly flow will increase rapidly tonight ahead of this system. Should see temperatures fall to their minimums during the late evening hours, then steady off/rise during the overnight hours. This situation is rather similar to what we saw last Thursday night into Friday morning. In similar fashion there is a risk for some light freezing rain across the eastern Ozarks between 3-8 AM. Temperatures look to hold right near the freezing mark during this time frame, especially in the valleys and lower lying areas of Dent/Shannon/Oregon counties. This will not be a widespread risk, nor are we expecting more than just a thin glaze of patchy accumulation. Nevertheless, this could cause brief travel challenges for the morning rush. Main forcing with this system will be targeting areas to our north. Warm advection regime will spark isolated to widely scattered showers after midnight, and this will get more organized along a front that will quickly move through the area during the daylight hours of Monday morning. Rainfall amounts will be on the order of hundredths of an inch in most locations. Central Missouri could see totals in the one to two tenths of an inch range. As fast as rain moves in, it will exit to the east and we should see some clearing during the afternoon. Temperatures will continue to remain tricky, but stay seasonable for the time of year. Highs should range from the 40s east to mid 50s west. .LONG TERM...(Monday Night through Sunday) Issued at 146 PM CST SUN FEB 16 2014 Milder temperatures will begin to move in for Tuesday through the middle part of the week. Winds will become breezy especially over the western half of the area on Tuesday afternoon. Will have to watch for elevated fire weather conditions Tuesday afternoon depending on gusty winds and the lower atmosphere mixing out. The next storm system to affect the area will be moving in Wednesday night through Thursday. Cold front will move into the area very late Wednesday night into Thursday morning. Widespread rainfall is expected with embedded thunder. The better dynamics and thermal profiles for stronger convection will be just off to our southeast with an earlier passage of the cold front during the day through most of the Ozarks. Average rainfall amounts will range from a quarter to half an inch. Cooler weather will follow for the end of the week into next weekend. The models are in disagreement with the Friday night into Saturday time frame. The GFS keeps the area dry with a west- northwest flow and high pressure in control. The ECMWF has a robust shortwave moving through the area with quick round of precip and colder solution. At this time...have leaned more towards the ECMWF solution for the weekend time frame with precip chances Friday night into Saturday and colder temperatures. && .AVIATION...(For the 06Z TAFS through 06Z Monday Night) Issued at 1154 PM CST SUN FEB 16 2014 A quick moving storm system will bring multiple impacts to the area over the next 18 hours. First off, low level wind shear will continue into early Monday morning as a low level jet stream remains over the region. Brisk and gusty southeasterly surface winds will also persist overnight. We will also see showers develop with even a few thunderstorms possible. At this time, we think the best threat for any thunderstorms will be around Springfield late tonight and early Monday morning. We have covered this with a TEMPO group. Weather models have backed off somewhat on MVFR potential late tonight and early Monday morning. We therefore brought MVFR in as a TEMPO group instead of going with prevailing groups. A cold front will then sweep through the area around mid-morning which will bring an end to the rain showers. Winds will become brisk and gusty out of the northwest behind the front with clouds clearing by early afternoon. Winds will then quickly diminish Monday evening. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ UPDATE...Schaumann SHORT TERM...Gagan LONG TERM...Griffin AVIATION...Schaumann
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1150 PM CST SUN FEB 16 2014 .UPDATE... ISSUED AT 1150 PM CST SUN FEB 16 2014 SNOWFALL ACROSS THE FA HAS BECOME LESS ORGANIZED AS WE ARE IN BETWEEN STRONGER FORCING MECHANISMS. ANOTHER STRONGER BAND OF SNOW (NOW JUST WEST OF JAMESTOWN) WILL CONTINUE TO PROPAGATE EAST/NORTHEAST PRODUCING ANOTHER 1-3 INCHES FROM ITS CURRENT LOCATION INTO NW MN. THE LATEST RAP GUIDANCE SUGGESTS ANOTHER STRONGER BAND OF SNOWFALL WILL AFFECT WC MN TOWARD 12Z (ALTHOUGH THE HEAVIEST SNOWFALL WOULD BE JUST EAST OF THE FA). DID NOT MAKE MUCH CHANGE TO THE GRIDS AS THEY BASICALLY DEPICT THIS OUTCOME. WINDS ALOFT ARE NOT MIXING VERY EFFICIENTLY...AND WILL TAME DOWN THE BLOWING SNOW MENTION. && .SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT) ISSUED AT 319 PM CST SUN FEB 16 2014 SNOW AMOUNTS AND TIMING REMAINS THE ISSUE. 12Z MODELS AND SHORT RANGE MODELS BACKED OFF ON TIMING OF MAIN SNOW BAND NOT ARRIVING INTO THE RED RIVER VALLEY TIL 03-06Z AND EASTERN FCST AREA AFTER 06Z. HRRR/RAP/18Z NAM CATCHES ONTO SNOW BANDS IN EASTERN MONTANA DEVELOPING NORTH OF SURFACE LOW IN SOUTHEASTERN MONTANA AND NEAR SHORT WAVE MOVING THRU MONTANA. AHEAD OF THIS MAIN PRECIPITATION BAND IS INITIAL WARM ADVECTION BAND THAT HAS BEEN MOVING EAST SLOWLY THRU WESTERN MANITOBA INTO ERN ND. SNOW WITH THIS BAND LOOKS GOOD ON RADAR BUT OBS INDICATE SNOWFALL PATCHY. UNSURE EXACTLY HOW IT WILL EVOLVE...BUT MAIN UPPER TROUGH IS STILL OVER WRN/CNTRL MONTANA AND ALL MODELS SHOW GOOD UPPER LEVEL DIVERGENCE AHEAD OF IT AND DECENT 700 MB VERTICAL MOTION ALONG WITH GOOD ISENTROPIC LIFT ALONG THE 290K SURFACE AHEAD OF SYSTEM SPREADING INTO ERN ND/NW MN TONIGHT. SO DESPITE A BIT LATER START STILL LOOKING FOR SAME IDEA IN TERMS OF SNOW TOTALS WITH 1-2 FAR WEST TO 3 OR SO IN THE RED RIVER VALLEY TO 4-5 EASTERN FCST AREA. SNOW WILL END IN THE RRV BY 12Z AND IN THE EAST BY 15Z. SOUTH- SOUTHEAST WINDS GUSTY TO 30 KTS AT TIMES THIS AFTN WITH NAM BUFKIT SOUNDINGS INDICATING PEAK MIXING IN LOWEST LAYERS 00Z-03Z IN THE RED RIVER VALLEY WHERE 28-30 KTS AVAILABLE. PUBLIC REPORTS INDICATE LOW LEVEL BLOWING SNOW/DRIFTING AND IN SPOTS POOR VISIBILITY. WILL MAINTAIN THIS IDEA INTO THE EVENING. WHERE SNOW DOES OCCUR WITH WIND NEAR BLIZZARD CONDITIONS WILL OCCUR BUT WINDS APPEAR TO BE BLO BLIZZARD THRESHOLD UNLESS SOMETHING CHANGES. THUS WINTER WX ADVISORY LOOKS GOOD...EVEN FOR WESTERN FCST AREA WHERE SNOW TOTALS ARE BLO ADV THRESHOLDS FOR SNOWFALL. CLEARING WILL MOVE IN MONDAY BEHIND THE FRONT WITH A WEST WIND AND WARMER AIRMASS WITH HIGHS 30-35 IN MOST AREAS MON AFTN. MONDAY NIGHT WILL BE MILD AS WELL WITH TEMPS HOLDING UP WITH WEST BREEZE AND SOME MID LEVEL CLOUDS MOVING BACK IN AS A SHORT WAVE MOVES EAST INTO NORTH DAKOTA. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 319 PM CST SUN FEB 16 2014 AFOREMENTIONED SHORT WAVE WILL MOVE INTO MINNESOTA TUESDAY AND MAY PRODUCE A LITTLE LIGHT SNOW IN THE LAKE OF THE WOODS REGION SO KEPT LOW POPS. OTHERWISE PRETTY MILD AGAIN AS SFC FLOW REMAINS WEST OR SOUTHWEST. HIGH PRESSURE DROPS IN TUES NIGHT...THEN SOUTHEASTERLY FLOW WILL PICK UP WED AFTN AHEAD OF NEXT LOW TO MOVE THROUGH SOUTHERN CANADA. WILL RESTRICT SOME POPS FOR LIGHT SNOW AHEAD OF THIS SYSTEM TO THE AFTN IN NE ND. OR WEDNESDAY NIGHT THROUGH SUNDAY.. LOW AMPLITUDE PROGRESSIVE FLOW BEGINS TO AMPLIFY THIS PERIOD. UPPER RIDGE FORECAST TO REBUILD ALONG 140W WITH TROUGH NEAR 90W. BY THE END OF THE PERIOD THE PATTERN SHIFTS EAST ABOUT 10 DEGREES PUTTING THE NORTHERN PLAINS BACK INTO A COLDER PATTERN. FOR WEDNESDAY EVENING INTO THURSDAY A STRONG LOW TRACKS SLOWLY JUST NORTH OF THE INTERNATIONAL BORDER. LIGHT SNOWS FORECAST AHEAD OF THE FRONT ON THURSDAY IN UPGLIDE ZONE...SIMILAR TO SYSTEM GOING THROUGH REGION TODAY AND TONIGHT. MODELS IN FAIR AGREEMENT THAT WRAP AROUND SNOWS WILL MOVE ACROSS MAINLY THE NORTHERN HALF OF THE REGION. LIGHT SNOW WILL LINGER IN THE EASTERN CWFA INTO THURSDAY EVENING. COLDER AIR PUSHES BACK ACROSS THE CWFA ON FRIDAY. FOR LATE FRIDAY INTO SATURDAY A SYSTEM THAT THE MODELS HAVE TRENDED SOUTH WITH BRUSHES THE FAR SOUTHERN CWFA. THE GFS/DGEX ARE MOST BULLISH WITH QPF WHILE THE ECMWF KEEPS THE FA DRY UNDER SURFACE HIGH PRESSURE... AND THE GEM HAS SOME -SN. MODELS TEND TO AGREE THERE WILL BE SOME WEAK LOW - MID LEVEL ISENTROPIC UPGLIDE. WITH CYCLONIC FLOW IN DEEPENING UPPER TROUGH FEEL LOW END POPS AT THIS POINT OK. THE EXTENDED PERIOD ENDS COLD AND DRY...THE COMMON THEME FOR THIS WINTER. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1150 PM CST SUN FEB 16 2014 PERIODS OF SNOW...AND MVFR/IFR CONDITIONS...WILL CONTINUE THROUGH THE NIGHTTIME HOURS. THESE CONDITIONS WILL END FROM WEST TO EAST MONDAY MORNING...WITH VFR CONDITIONS MOVING IN. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...WINTER WEATHER ADVISORY UNTIL 6 AM CST MONDAY FOR NDZ006>008- 014>016-024-026>030-038-039-049-052>054. MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST MONDAY FOR MNZ001>004-007- 029-030-040. WINTER WEATHER ADVISORY UNTIL 9 AM CST MONDAY FOR MNZ005-006-008- 009-013>017-022>024-027-028-031-032. && $$ UPDATE...TG SHORT TERM...RIDDLE LONG TERM...EWENS/RIDDLE AVIATION...TG
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1100 PM CST SUN FEB 16 2014 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 316 PM CST SUN FEB 16 2014 MAIN SHORT TERM FORECAST IS ON HEAVY SNOW EXPECTED MONDAY MORNING. CURRENTLY AS OF 20Z...WATER VAPOR IMAGERY AND RAP 500MB HEIGHT ANALYSIS SHOWED A SHORTWAVE TROUGH EXTENDING FROM ALBERTA THROUGH IDAHO...RIDGING FROM TEXAS INTO SOUTHERN MANITOBA...AND TROUGHING OVER THE NORTHEAST U.S.. WITH THE FORECAST AREA IN THE INFLECTION POINT EAST OF THE UPPER RIDGE AXIS...HIGH PRESSURE EXISTS AT THE SURFACE WITH SUBSIDENCE AND DRYING IN THE LOW TO MID LEVELS. THIS RESULTED IN CLEARING OF LOW CLOUDS THIS MORNING. HOWEVER...MID AND HIGH CLOUDS ARE QUICKLY SPREADING EAST FROM THE DAKOTAS INTO THE FORECAST AREA. THESE ARE ASSOCIATED WITH A WARM ADVECTION REGIME IN PLACE ON THE BACK SIDE OF THE SURFACE HIGH. PRECIPITABLE WATER ANALYSIS SHOWED VALUES AROUND 0.5 INCH FROM OKLAHOMA INTO WESTERN NORTH DAKOTA...COMPARED TO 0.1-0.25 INCHES OVER THE FORECAST AREA. MODELS REMAIN CONSISTENT WITH THE EXPECTED SNOW TO MOVE ACROSS THE AREA LATER TONIGHT INTO MONDAY. THE MAIN FEATURE RESPONSIBLE FOR THE SNOW IS THE SHORTWAVE TROUGH OVER IDAHO WHICH REACHES THE FORECAST AREA AT 18Z MONDAY. ITS WORTH NOTING THAT BETWEEN 12-18Z MONDAY THE SHORTWAVE TROUGH INTENSIFIES AND TAKES ON A NEGATIVE TILT. IN RESPONSE LIFT GREATLY INCREASES AHEAD OF THE TROUGH...AND TO BALANCE SUBSIDENCE INCREASES BEHIND IT. THE LIFT WILL ACT ON THE PLUME OF 0.5 INCH PRECIPITABLE WATER SEEN OVER THE WESTERN DAKOTAS TO PRODUCE THE SNOW. SOME INTERESTING FACETS FOR TONIGHT INTO MONDAY... 1. AS THE LOW LEVEL JET INCREASES TONIGHT AHEAD OF THE TROUGH...IT APPEARS A WARM ADVECTION BAND OF SNOW WILL DEVELOP FROM CENTRAL INTO SOUTHEAST MN AROUND MIDNIGHT...THEN LIFT NORTHEASTWARD THROUGH THE REST OF THE NIGHT. UNSURE HOW MUCH OF THIS SNOW WILL REACH THE SURFACE AS MODELS DEPICT LEFTOVER DRY AIR BETWEEN 750-900MB THAT NEEDS SATURATING. THEREFORE...PRECIPITATION CHANCES ARE KEPT LOWER PRIOR TO 09Z. AS WE APPROACH 12Z...THE BIG BATCH OF SNOW ASSOCIATED WITH THE WARM CONVEYOR BELT AND DPVA AHEAD OF THE SHORTWAVE TROUGH WILL ENCOMPASS MUCH OF THE WESTERN HALF OF THE FORECAST AREA. 2. THERE IS A VERY TIGHT MODEL CONSENSUS FOR 12-18Z MONDAY TO BE THE TIME PERIOD OF HEAVIEST QPF/SNOW. WITH A LITTLE NEGATIVE EPV THROWN IN IN THE MID LEVELS...EASILY COULD SEE SOME CONVECTIVE NATURE TO THE SNOW. SNOWFALL RATES OF 1 INCH PER HOUR EASILY SEEM PLAUSIBLE FOR A COUPLE HOURS...KNOCKING VISIBILITIES DOWN TO 1/4 MILE. THESE RATES SHOULD OCCUR AT THE WORST TIME...MORNING COMMUTE. ALTHOUGH TOTAL SNOWFALL AMOUNTS OVER THE SOUTHWEST HALF OF THE FORECAST AREA ARE ONLY FORECAST RIGHT NOW IN THE 4-5 INCH RANGE...BELOW WARNING CRITERIA...ISSUED A WARNING BASED ON TIME OF DAY. FAR WESTERN AREAS SUCH AS ROCHESTER LOOK TO GET INTO SOME BLOWING SNOW TOO. ALSO WARNED FOR THAT AREA BECAUSE THE 16.12Z MODELS HAVE TRENDED QPF UP ACROSS THE SOUTHERN PORTION OF THE FORECAST AREA...NOW NEAR 1/3 OF AN INCH. 3. WITH THE STRONG SUBSIDENCE OCCURRING ON THE BACK SIDE OF THE TROUGH...SKIES SHOULD CLEAR WEST TO EAST DURING THE MID AFTERNOON INTO THE EVENING HOURS. THIS SHOULD MAKE THE AFTERNOON COMMUTE MUCH MORE MANAGEABLE...PROVIDED ROADS ARE CLEANED UP IN TIME. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 316 PM CST SUN FEB 16 2014 AFTER AN ACTIVE SHORT TERM PERIOD...THE LONG TERM LOOKS FAIRLY QUIET. THERE ARE SOME ITEMS OF INTEREST... 1. TEMPERATURES CLIMBING ABOVE NORMAL TUESDAY AND WEDNESDAY. THE FLOW PATTERN BECOMES MORE ZONAL...ALLOWING PACIFIC AIR TO FLOW INTO THE FORECAST AREA. WARMEST DAY SHOULD COME TUESDAY AHEAD OF A COLD FRONT PASSING THROUGH LATE IN THE DAY. 850MB TEMPS ARE PROGGED TO CLIMB TO 4-6C...WHICH SHOULD ALLOW HIGHS TO TOP OUT AS HIGH AS THE LOW 40S. SLIGHTLY COOLER CONDITIONS ARE FORECAST ON WEDNESDAY BEHIND THE FRONT. IT SHOULD BE NOTED THAT THE LAST TIME LA CROSSE WAS ABOVE NORMAL WAS JANUARY 30TH. AT ROCHESTER...IT WAS JANUARY 16TH. 2. STORM SYSTEM LIFTING OUT OF THE CENTRAL PLAINS WEDNESDAY NIGHT. ECMWF RUNS FROM 15.00Z AND PRIOR TOOK THIS SYSTEM AND REALLY INTENSIFIED IT WHILE LIFTING NORTHEAST THROUGH THE FORECAST AREA. THAT CHANGED WITH THE 15.12Z ECMWF AND LATEST 16.12Z ECMWF/CANADIAN/GFS CONTINUE TO BRING THE SYSTEM INTO LOWER MICHIGAN BY THURSDAY EVENING. ALONG ITS TRACK...ASSISTED BY A NORTHERN STREAM SHORTWAVE TROUGH CROSSING THE UPPER MIDWEST...A BAND OF PRECIPITATION IS LOOKING MORE LIKELY TO MOVE THROUGH THE AREA LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. ENOUGH WARM AIR LOOKS TO GET PULLED UP INTO THE SYSTEM TO ALLOW FOR A MIX OF PRECIPITATION IN SOUTHEAST SECTIONS OF THE FORECAST AREA. SOMETHING WORTH MONITORING. 3. SYSTEM TO BRING A BRIEF BOUT OF SNOW FRIDAY INTO FRIDAY NIGHT. BOTH THE 16.12Z GFS AND CANADIAN BRING A SHORTWAVE TROUGH AND DEFORMATION SNOW ACROSS THE FORECAST AREA DURING THIS TIME FRAME. HOWEVER...THERE IS NO SIGN OF THIS SHORTWAVE IN THE ECMWF. FOR NOW JUST HAVE LOW CHANCES OF SNOW IN THE FORECAST. 4. HEADING BACK TO BELOW NORMAL BEGINNING THURSDAY NIGHT. ALL MODELS HAVE MATCHED UP WELL WITH CFS FORECASTS SUGGESTING TEMPERATURES GOING BACK BELOW NORMAL AS TROUGHING REESTABLISHES ITSELF OVER THE UPPER MIDWEST. BY THE WEEKEND...850MB TEMPS MAY GET STUCK BELOW -10C AGAIN...WITH SOME HINTS OF -20C AIR COMING AT THE AREA JUST BEYOND THE LONG TERM PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1100 PM CST SUN FEB 16 2014 WINTER STORM WILL BRING SNOW...LOW VSBYS/CLOUDS...AND GUSTY WINDS TO THE REGION MONDAY MORNING. INCH PER HOUR SNOWFALL RATES ARE EXPECTED FOR A FEW HOURS...AND BLSN SHOULD OCCUR AT KRST FOR A GOOD PORTION OF THE DAY. TIMING ON WHEN THE HEAVIEST SNOW MOVES IN...AND MOVES OUT...PRESENTS SOME CHALLENGES. BUFKIT SOUNDINGS SUGGEST A FEW HOURS EARLIER THAN MODELED QPF FIELDS. TRENDS IN THE MODELS HAVE BEEN A BIT SLOWER THOUGH...WITH LATEST RAP/HRRR/NAM12 ALSO SUGGESTING A DELAY IN HEAVY SNOW ONSET. ENOUGH AGREEMENT IN THE MODELS TO FOLLOW SUIT...AND WILL ADJUST TAFS. MEANWHILE...MID LEVEL FRONTOGENETIC WING COULD PRODUCE A BAND OF SNOW WELL AHEAD OF THE MAIN AREA SNOW. MOST OF THIS WOULD PROBABLY BE 4-P6SM FOR VSBY. STILL FOCUSING ON A 4 HOUR TIME FRAME FOR THE HEAVY SNOW. SOUTHEAST WINDS HAVE INCREASED AS THE PRESSURE GRADIENT TIGHTENS AHEAD OF THE SHORTWAVE TROUGH/SFC LOW. SOME SLACKENING CAN BE EXPECTED AS THE SNOW COMES IN - WITH A BAGGIER GRADIENT. STILL...IT WILL BE STRONG ENOUGH TO BLOW/DRIFT THE SNOW AT KRST...AND MUCH OF THE VSBY REDUCTIONS OUTSIDE OF THE HEAVY SNOW CAN BE ATTRIBUTED TO THAT. THE SYSTEM/S COLD FRONT SHOULD MOVE THROUGH IN THE 21-00Z MON TIME FRAME...WITH A SCATTERING OUT OF THE CLOUD DECK. ANTICIPATE REFINEMENTS TO THE FORECAST AS RADAR TRENDS MAKE SNOW ONSET/EXIT MORE EVIDENT. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...WINTER STORM WARNING FROM 3 AM TO 3 PM CST MONDAY FOR WIZ017-029- 032>034-041>044-053>055-061. MN...WINTER STORM WARNING FROM 3 AM TO 3 PM CST MONDAY FOR MNZ079- 086>088-094>096. IA...WINTER STORM WARNING FROM 3 AM TO 3 PM CST MONDAY FOR IAZ008>011- 018-019-029-030. && $$ SHORT TERM...AJ LONG TERM....AJ AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
801 AM CST MON FEB 17 2014 .DISCUSSION... 330 AM CST SHORT TERM (THROUGH TONIGHT)... MAIN CONCERNS ARE WITH INCREASED POTENTIAL FOR A PERIOD OF HEAVY SNOW THIS AFTERNOON FOR THE ENTIRE CWA WHICH COULD HAVE SIGNIFICANT IMPACTS WITH WHITE OUT CONDITIONS UNDER POSSIBLE TWO TO THREE INCH PER HOUR SNOWFALL RATES SOME OF WHICH COULD FALL UNDER CONVECTIVE ELEMENTS...WITH AREA WIDE 4 TO 8 INCHES LIKELY AND SOME ISOLATED AMOUNTS NEAR 10 INCHES DEFINITELY NOT OUT OF THE QUESTION. IMPRESSIVE STRONG STORM ANTICIPATED TO TAKE SHAPE OVER THE AREA LATER TODAY CAN BE OBSERVED ON SATELLITE IMAGERY...WITH MID/UPPER LEVEL TROUGH CURRENTLY PUSHING EAST THROUGH THE NORTHERN PLAINS. OUT AHEAD OF THIS SYSTEM...LATEST RAP ANALYSIS DEPICTING STRONG ISENTROPIC ASCENT OCCURRING ACROSS THE ENTIRE REGION INCLUDING LOCALLY OVER THE CWA. THIS HAS RESULTED IN PERSISTENT MID/HIGH LEVEL CLOUD COVER TO STREAM OUT AHEAD OF THIS SYSTEM...WITH CURRENT RADAR IMAGERY LIGHTING UP WITH SOME DECENT RETURNS. ALTHOUGH RATHER DRY AIR IN PLACE HAS LIMITED ANY PRECIP TO REACH THE SURFACE AND ANTICIPATE FOR THIS TO FURTHER BE THE CASE OVER THE NEXT COUPLE OF HOURS. WHAT COULD BE EXPECTED IN THE NEAR TERM ARE SOME ISOLATED FLURRIES PRIMARILY OVER THE NORTHWEST HALF OF THE CWA...WITH RFD CURRENTLY REPORTING 9 MILES IN LIGHT SNOW. ISENTROPIC ASCENT WILL CONTINUE THIS MORNING...WITH SHORT TERM GUIDANCE HINTING AT THE POSSIBILITY FOR FURTHER PRECIP DEVELOPMENT ENTERING THE SOUTHWEST CWA JUST AFTER THE 12Z TIME FRAME. PREVIOUSLY DISCUSSED WARMING/WARM WEDGE STILL ANTICIPATED HERE THIS MORNING AND COULD INITIALLY BRING A WINTRY MIX BUT STAYING CONFINED TO THE SOUTHERN HALF OF THE CWA...PRIMARILY SOUTH OF THE I80 CORRIDOR. IF ANYTHING WERE TO OCCUR DURING THIS TIME FRAME...ANTICIPATE IT TO BE ON THE LIGHTER SIDE WITH THE PREVIOUSLY MENTIONED DRIER AIR STILL NEEDING TO BE OVERCOME. NONETHELESS...WITH AN ANTICIPATED SLOWING TREND WITH THE EVOLUTION OF TODAY`S SYSTEM...THIS WINTRY MIX COULD BE MORE PREVALENT THAN PREVIOUSLY THOUGHT TO START THE PERIOD. SO HAVE INCLUDED CHANCE ZR/IP IN THE GRIDS THROUGH 15Z. CAN MAKE OUT TWO SEPARATE PIECES OF STRONG ENERGY TRAVERSING THE MID LEVEL FLOW...NOW WITH ALL GUIDANCE IN STRONG AGREEMENT WITH THE EVOLUTION OF THIS ENERGY AS IT APPROACHES THE REGION. ABOUT THE ONLY DIFFERENCE AT THIS TIME IS SOME SLIGHT TIMING DIFFERENCES WITH THE APPROACH OF THE BETTER FORCING/PRECIP LATER TODAY. A CONTINUED SLOWER TREND HAS BEEN THE PREFERRED TREND HERE THIS MORNING...AND HAVE DELAYED HIGHEST POPS TODAY. ALTHOUGH DID NOT OVERLY STRAY TOO MUCH WITH THE PREVIOUSLY MENTIONED ISENTROPIC ASCENT AND POTENTIAL PRECIP OUT AHEAD OF IT. HAVE CONTINUED THE MENTION IN THE GRIDS FOR A MIX OF SLEET FOR LATER IN THE MORNING...MAINLY FOR THE SOUTHERN TIER OF COUNTIES. ALTHOUGH THERMAL PROFILES WOULD BE SUPPORTIVE OF THIS WINTRY MIX CONTINUING...HAVE LIMITED MENTION OF THIS MIX AS BETTER FORCING SHOULD BE ARRIVING DURING THIS TIME. WHATEVER LINGERING WARM WEDGE IN THE COLUMN WILL QUICKLY COOL THE COLUMN TO THE WET BULB AS STRONG DYNAMIC FORCING ARRIVES...WITH ANY MIX QUICKLY CHANGING OVER TO ALL SNOW. ONCE AGAIN...ALL GUIDANCE POINTING AT SIGNIFICANT SNOWFALL RATES BEGINNING AT SOON AS LATE MORNING FOR THE WESTERN CWA. TWO PIECES OF ENERGY WILL PHASE TOGETHER BY EARLY AFTERNOON...WITH THIS MID/UPPER LEVEL TROUGH BECOMING NEGATIVELY TILTED. AS THIS OCCURS...ATTENDANT LOW TO DEEPEN AS IT MOVES THROUGH CENTRAL ILLINOIS WITH 850MB LOW REALLY BEGINNING TO TAKE SHAPE. STRONG DYNAMICAL FORCING ASSOCIATED WITH THIS MID LEVEL TROUGH AND SIGNIFICANT HEIGHT FALLS WILL ALLOW FORCING TO SWING THROUGH THE CWA BY LATE MORNING INTO THE EARLY AFTERNOON. ASSOCIATED FRONTOGENETICAL FORCING WILL LIKEWISE PUSH EAST THROUGH THE AREA THIS AFTERNOON...WITH THE PRESENCE OF NEGATIVE EPV. THIS PRESENCE OF BOTH SLANTWISE AND UPRIGHT MOTIONS ARE LEADING FOR SOME REALLY IMPRESSIVE VERTICAL MOTION...WITH FORECAST OMEGA AMONG ALL GUIDANCE SOME OF THE HIGHEST IVE OBSERVED IN SOME TIME. THE STRONGEST VERTICAL MOTIONS ARE EXPECTED TO PUSH EAST TO WEST ACROSS THE CWA INTO THE EARLY AFTERNOON TIME FRAME AND CONTINUING THROUGH MID/LATE AFTERNOON...WITH FORCING CENTERED RIGHT IN THE MIDDLE OF THE CWA. ALTHOUGH CURRENT FORECAST SNOW TOTALS ARE THE HIGHEST IN THESE LOCATIONS...TOTALS DONT STRAY TOO MUCH FROM THE AMOUNTS ACROSS THE REMAINING CWA. THIS IS IN DUE TO PART TO HOW UNSTABLE THIS SYSTEM WILL BE...INCLUDING CONVECTIVE INSTABILITY. BOTH NAM/GFS SHOWING IMPRESSIVE MUCAPE TO PUSH NORTHEAST THROUGH THE CWA AS EARLY AS MID MORNING...AND THE BEGINNING STAGES OF THIS CAN ALREADY BE OBSERVED TO OUR WEST/SOUTHWEST WITH LATEST RAP ANALYSIS DEPICTING 100-200 J/KG OVER IOWA/MISSOURI/KANSAS. WITH SREF GUIDANCE INDICATING HIGH PROBABILITIES OF AT LEAST 50-100 J/KG OF MUCAPE TO MOVE OVERHEAD LATER TODAY...FEEL THAT THE NAM/GFS SOLUTION OF 100 TO ALMOST 300 J/KG IS NOT OF THE QUESTION. THE PRESENCE OF THIS STRONG FORCING...STRONG INSTABILITY AND ABUNDANCE OF MOISTURE NOT ONLY LIKELY BEING PRESENT BUT ALSO COMING TOGETHER...HAS STEERED THE FORECAST SIGNIFICANTLY MORE PESSIMISTIC THIS MORNING. HEAVIEST SNOW...WHICH WILL FALL WITH HIGH INTENSITIES AND POSSIBLY AT A RATE OF TWO TO THREE INCHES PER HOUR AT TIMES SHOULD ARRIVE THE FAR WESTERN CWA BY MID/LATE MORNING...AND THEN SPREADING EAST THROUGH THE REMAINING CWA BY EARLY AFTERNOON. EXPECT THESE HIGH SNOWFALL INTENSITIES THROUGH MID TO LATE AFTERNOON...AND POSSIBLY CONTINUE INTO THE EARLY EVENING FOR THE EASTERN THIRD OF THE CWA. THIS HEAVY SNOW WILL QUICKLY ACCUMULATE ON ROADS WITH NEAR VISIBILITY LIKELY UNDER THIS HEAVY SNOW...CREATING VERY HAZARDOUS CONDITIONS. AS WAS MENTIONED PREVIOUSLY...THE HIGHEST TOTALS ARE IN THE CWA ALIGNED WITH THE BETTER FORCING...BUT FEEL THAT ANY LACKING FORCING WILL BE SUPPLEMENTED WITH THE CONVECTIVE NATURE OF THIS SYSTEM. CONVECTIVE ALLOWING MODELS INDICATE THE PRESENCE OF THUNDER BREAKING OUT BY EARLY AFTERNOON. ALTHOUGH GUIDANCE IS HINTING THAT THIS WILL BE MORE PREFERRED ACROSS THE SOUTHERN CWA...WITH GUIDANCE INDICATING INSTABILITY INTO SOUTHERN WISCONSIN...HAVE INCLUDED A CHANCE FOR THUNDER IN THE GRIDS FOR THE ENTIRE CWA. ITS THESE CONVECTIVE ELEMENTS WHICH COULD SUPPLEMENT HIGHER RATES AND RESULTANT SNOWFALL TOTALS. SO FOR THE WARNING ISSUED OVERNIGHT...WILL HAVE AREA WIDE 4 TO 8 INCHES WITH THE POSSIBILITY OF SLIGHTLY HIGHER AMOUNTS NEAR 10 INCHES. IF THESE CONVECTIVE ELEMENTS WERE TO MATERIALIZE...THEN AREAS DEFINITELY COULD OBSERVE THESE HIGHER AMOUNTS. ALSO...ITS POSSIBLE THAT THESE AMOUNTS COULD BE OBSERVED IN A 4-6 HOUR WINDOW. HAVE THE WARNING ENDING EARLY THIS EVENING FOR THE WESTERN CWA AND THEN AT 3Z LATER THIS EVENING FOR THE EASTERN CWA. IF LATER GUIDANCE THIS MORNING CONTINUES TO SUPPORT CURRENT THINKING...SITUATION FORECAST TO UNFOLD LATER THIS AFTERNOON WILL DEFINITELY BE SOMETHING TO NOT TAKE LIGHTLY. RODRIGUEZ LONG TERM (TUESDAY THROUGH SUNDAY)... FAST ON THE HEELS OF TODAY`S DEPARTING SYSTEM WILL BE ANOTHER NORTHERN STREAM SYSTEM TRACKING ACROSS SOUTHERN CANADA. VERY STRONG WARM AIR ADVECTION WILL BE UNDERWAY ALOFT TUES MORNING AND EVENTUALLY DEVELOPING AT THE SURFACE AS SOUTHERLY WINDS PICK UP. DEEP AND FRESHLY RELOADED SNOW COVER OVER THE AREA WILL UNDOUBTEDLY RETARD THE WARM UP...BUT STILL THINK TEMPS SHOULD MANAGE TO CLIMB ABOVE FREEZING MOST AREAS FOR THE FIRST TIME IN WEEKS TUES AFTERNOON. WEAK COLD FRONT MOVES THROUGH TUESDAY EVENING WITH LITTLE FANFARE AND BARELY TIME FOR MUCH COLD AIR TO SEEP SOUTHWARD BEFORE WARM AIR ADVECTION BEGINS AGAIN LATER WEDNESDAY IN ADVANCE OF LATE WEDNESDAY NIGHT INTO THURSDAY`S WELL ADVERTISED BIG HULLABALOO. NOT SURPRISINGLY GIVEN THE COMPLEXITY OF THE PATTERN AND DEALING WITH PHASING ISSUES...MODELS HAVE FLOPPED BACK FROM THEIR PREVIOUS FLIP WITH MORE EMPHASIS ON A STRENGTHENING SOUTHERN LOW LIFTING NORTHEAST INTO THE GREAT LAKES. STILL SOME DIFFERENCES IN STRENGTH AND EXACT TRACK...BUT ECMWF/GFS NOW AGREE ON TAKING A SFC LOW OVER NORTHERN MISSOURI 18Z THURS NORTHEAST TO THE UPPER GREAT LAKES BY THURSDAY NIGHT...WITH CONSIDERABLE DEEPEN OF THE LOW ALONG THE WAY. ECMWF AND 06Z NAM ARE STRONGER AND A BIT FARTHER NORTHWEST...BUT NAM/GFS/ECMWF ALL HAVE THE SAME GENERAL IDEA. FIRST FORECAST ISSUE WILL BE WEDNESDAY NIGHT AS INITIAL BATCH OF WAA PRECIP BREAKS OUT AND LIFTS NORTH ACROSS THE AREA. MODEL QPF REMAINS FAIRLY HIGH AND WITH SOME ELEVATED INSTABILITY ALSO EVIDENT IN THE MODELS...CERTAINLY ENOUGH TO WARRANT A CONTINUED SLIGHT CHANCE MENTION OF THUNDERSTORMS. THE BIGGEST PROBLEM WED NIGHT WILL BE HOW FAST THE 2M TEMPS WARM UP. WHILE VERY STRONG WAA WILL BE TAKING PLACE ALOFT...INITIALLY EASTERLY WINDS OVER THE AREA AND DEEP SNOW PACK COULD ALLOW FOR A RATHER PROLONGED PERIOD OF FREEZING RAIN AND AN ICING THREAT DEPENDING ON SFC TEMPS. MANY OF THE MODEL SUGGEST A SURGE OF WARM LATE WEDNESDAY NIGHT...ESPECIALLY SOUTHERN CWA...BUT ITS GOING TO BE CLOSE. ONLY A MATTER OF A COUPLE DEGREES COULD MEAN THE DIFFERENCE BETWEEN A SIGNIFICANT ICING PROBLEM AND ALL RAIN AND THIS FAR OUT IT REALLY IS ANYONE`S GUESS WHAT SIDE OF 32F ANY ONE GIVEN AREA WILL END UP ON AS THE RAIN FALLS. CERTAINLY FARTHER NORTH WOULD STAND THE BETTER CHANCE OF FREEZING RAIN...BUT THE ICING POTENTIAL CANNOT BE RULED OUT EVEN OVER SOUTHERN PORTIONS OF THE CWA. THIS LATEST SWING IN THE MODELS TOWARD A MORE AMPLIFIED SOUTHERN LOW TRACKING NORTH IS BAD NEWS FOR IN THE HYDROLOGY DEPARTMENT. WHILE NOT AS HORRIFYING AS THE NIGHTMARE SCENARIO THE ECMWF HAD BEEN PAINTING A COUPLE DAYS AGO WITH 50 AND NEAR 60F DEWPOINTS TO THE WISCONSIN LINE...THE LATEST GUIDANCE DOES DRAG THE 40F ISODROSOTHERM FAR NORTH INTO THE AREA ON THURSDAY...WITH EVEN SOME 50F DEWPOINTS FAR SOUTHERN CWA. THE HIGHER THE DEWPOINTS THE MORE RAPID THE SNOW MELT WILL BE AND THE MORE OF A PROBLEM ANY MODERATE TO HEAVY RAIN THAT FALLS WILL POSE THURSDAY. TEMPS LOOK TO CLIMB SAFELY ABOVE FREEZING THURS AM EVEN NORTH TO THE WI BORDER ENDING THE FRZ RAIN THREAT...BUT WITH PWATS PROGGED TO CLIMB TO OVER AN INCH (200-250% OF NORMAL) THURSDAY THE POTENTIAL WILL EXIST FOR HEAVY RAINFALL. HAVE ALREADY BEEN HARPING ON ALL THE HYDRO CONCERNS IN THE ESF ISSUED FRIDAY AND UPDATED OVER THE WEEKEND AND REALLY NO BIG CHANGES IN THINKING AT THIS POINT OTHER THAN TO SAY THE FLOOD POTENTIAL IS LOOKING MORE OMINOUS THAN IT DID 24 HOURS AGO. STRONG COLD FRONT LOOKS TO SWEEP THROUGH THURSDAY EVENING BRINGING AN END TO THE RAIN AND POSSIBLE THUNDERSTORMS AND ALLOWING DRIER AND COLDER AIR TO FILTER INTO THE REGION. WHILE COLDER AIR FILTERS IN FOR THE WEEKEND WITH MEDIUM RANGE MODELS SUGGESTING ONE OR TWO SYSTEM COULD AFFECT THE REGION WITH WHAT WOULD PROBABLY BE SOME SNOWFALL. TIMING AND TRACK OF THESE LOWER AMPLITUDE WAVES ARE ALL OVER THE PLACE IN THE MODELS SO ONLY CARRYING LOW CHANCES POPS FOR NOW. IZZI && .HYDROLOGY...330 AM CST LATEST MODEL GUIDANCE DOES LOOK MORE WORRISOME THAN IT DID 24 HOURS AGO REGARDING THE FLOOD POTENTIAL THURSDAY...POSSIBLY LINGERING INTO THE WEEKEND. MORE DETAIL METEOROLOGICAL DISCUSSION IS ABOVE. NO CHANGES REALLY TO THE PREVIOUS HYDROLOGICAL DISCUSSION OTHER THAN SLIGHTLY MORE SNOW AND SNOW WATER EQUIVALENT IS EXPECTED TO BE IN PLACE AFTER TODAY`S SNOW SYSTEM. WILL FRESHEN UP THE ESF AGAIN THIS MORNING BUT NOT PLANNING ANY BIG CHANGES. && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * BAND OF HEAVY SNOW THIS MORNING WITH VSBY LESS THAN A HALF MILE POSSIBLE...NEAR WHITE-OUT VERY BRIEFLY POSSIBLE. * HEAVY SNOW TO DEVELOP EARLY-MID AFTERNOON WITH OCNL VSBY BETWEEN 1/16SM AND 1/4SM EXPECTED * SLIGHT CHANCE OF THUNDERSTORM (THUNDERSNOW) IN THE MID-LATE AFTERNOON * STRONG SOUTHEAST WINDS WITH GUSTS TO AROUND 25KT EXPECTED. * QUICK IMPROVEMENT TO CIGS/VSBY AS SNOW ENDS EARLY THIS EVENING IZZI/BMD //DISCUSSION...UPDATED 12Z... A SHORT LIVED BUT INTENSE SNOW STORM WILL AFFECT THE AREA TODAY. RADAR ECHOS OVER DOWNSTATE ILLINOIS ARE INITIALLY EVAPORATING BEFORE REACHING THE GROUND...BUT SNOW COULD BEGIN TO PENETRATE THE LOW LEVEL DRY AIR AS EARLY AS MID MORNING...BUT MORE LIKELY BY LATE MORNING AND DEFINITELY BY EARLY AFTERNOON. MOST INTENSE SNOWFALL STILL LOOKS TO BE FOCUSED ON THE 19-23Z TIME FRAME FOR CHICAGO AND ALL INDICATIONS ARE THAT VSBY WILL DROP AT TIMES TO AT LEAST 1/4SM IF NOT LOWER WITH EVEN SOME THREAT OF +TSSN. SNOWFALL RATES COULD EXCEED 2 INCHES PER HOUR AT TIMES. STRONG SOUTHEAST WINDS THIS MORNING WILL DECREASE IN INTENSITY SOME AS THE SNOW PEAKS THIS AFTERNOON...BUT DIRECTION LIKELY TO REMAIN SE THROUGH MOST IF NOT ALL OF THE DURATION OF THE ACCUMULATING SNOW. INVERTED TROUGH SHOULD MOVE THROUGH THIS EVENING RESULTING IN WIND SHIFT TO WEST AND A QUICK WINDING DOWN OF THE SNOWFALL. IZZI //ORD AND MDW CONFIDENCE...UPDATED 14Z... * HIGH CONFIDENCE IN VSBY AT LEAST AS LOW AS HALF MILE 1430-1530Z. * HIGH CONFIDENCE IN ONSET TIME OF MOD-HVY SNOW +/- AN HOUR OR SO * MEDIUM CONFIDENCE IN OCNL VSBY 1/4SM OR LOWER WITH ACCUMULATION RATES OF 1"/HOUR OR GREATER * MEDIUM-HIGH CONFIDENCE ON END TIME OF SNOW MONDAY EVENING +/- AN HOUR OR SO * HIGH CONFIDENCE IN REMAINDER OF FORECAST ELEMENTS IZZI/BMD //OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z... TUESDAY NIGHT THROUGH WEDNESDAY...PREDOMINANTLY VFR. WEDNESDAY NIGHT...RAIN OR FZRA DEVELOPING. THURSDAY..RAIN/FOG/IFR LIKELY. FZRA POSSIBLE IN THE MORNING. FRIDAY...VFR PROBABLE. SATURDAY AND SUNDAY...SOME POTENTIAL FOR SNOW. IZZI && .MARINE... 324 AM CST HAVE HOISTED A GALE WARNING FOR A LARGE PORTION OF CENTRAL LAKE MICHIGAN FOR TODAY. THE DEEPER SFC LOW IN THE MODELS SHOULD RESULT IN A PERIOD OF SOUTHEAST GALES THIS MORNING INTO THE EARLY AFTERNOON BEFORE THE BAGGIER PRESSURE GRADIENT APPROACHES THE LAKE ASSOCIATED WITH THE INVERTED TROUGH NORTH OF THE LOW TRACKING ACROSS DOWNSTATE IL AND IN. BRIEF SHOT OF WESTERLY WINDS TONIGHT IN THE WAKE OF THE TROUGH AND DEPARTING LOW BEFORE SOUTHERLY WINDS BEGIN TO REALLY CRANK UP AGAIN ON TUESDAY AS ANOTHER STRONG LOW TRACK EAST ACROSS THE SOUTHERN CANADIAN PRAIRIES. COULD BE BORDERLINE SOUTHERLY GALES ON TUESDAY AFTERNOON AS WELL...BUT FOR NOW JUST STUCK WITH OCNL GALE WORDING IN THE GLF AND WILL LET NEXT SHIFT GET ANOTHER LOOK BEFORE DECIDING ON POSSIBLE GALE HEADLINES FOR TUESDAY. IZZI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011- ILZ012-ILZ019-ILZ020-ILZ021-ILZ032-ILZ039 UNTIL 6 PM MONDAY. WINTER STORM WARNING...ILZ006-ILZ013-ILZ014-ILZ022-ILZ023-ILZ033 UNTIL 9 PM MONDAY. IN...WINTER STORM WARNING...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9 PM MONDAY. LM...GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ868-LMZ870-LMZ872-LMZ874-LMZ876 UNTIL 3 PM MONDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 PM MONDAY. && $$ 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
NWS CHICAGO/ROMEOVILLE IL
549 AM CST MON FEB 17 2014 .DISCUSSION... 330 AM CST SHORT TERM (THROUGH TONIGHT)... MAIN CONCERNS ARE WITH INCREASED POTENTIAL FOR A PERIOD OF HEAVY SNOW THIS AFTERNOON FOR THE ENTIRE CWA WHICH COULD HAVE SIGNIFICANT IMPACTS WITH WHITE OUT CONDITIONS UNDER POSSIBLE TWO TO THREE INCH PER HOUR SNOWFALL RATES SOME OF WHICH COULD FALL UNDER CONVECTIVE ELEMENTS...WITH AREA WIDE 4 TO 8 INCHES LIKELY AND SOME ISOLATED AMOUNTS NEAR 10 INCHES DEFINITELY NOT OUT OF THE QUESTION. IMPRESSIVE STRONG STORM ANTICIPATED TO TAKE SHAPE OVER THE AREA LATER TODAY CAN BE OBSERVED ON SATELLITE IMAGERY...WITH MID/UPPER LEVEL TROUGH CURRENTLY PUSHING EAST THROUGH THE NORTHERN PLAINS. OUT AHEAD OF THIS SYSTEM...LATEST RAP ANALYSIS DEPICTING STRONG ISENTROPIC ASCENT OCCURRING ACROSS THE ENTIRE REGION INCLUDING LOCALLY OVER THE CWA. THIS HAS RESULTED IN PERSISTENT MID/HIGH LEVEL CLOUD COVER TO STREAM OUT AHEAD OF THIS SYSTEM...WITH CURRENT RADAR IMAGERY LIGHTING UP WITH SOME DECENT RETURNS. ALTHOUGH RATHER DRY AIR IN PLACE HAS LIMITED ANY PRECIP TO REACH THE SURFACE AND ANTICIPATE FOR THIS TO FURTHER BE THE CASE OVER THE NEXT COUPLE OF HOURS. WHAT COULD BE EXPECTED IN THE NEAR TERM ARE SOME ISOLATED FLURRIES PRIMARILY OVER THE NORTHWEST HALF OF THE CWA...WITH RFD CURRENTLY REPORTING 9 MILES IN LIGHT SNOW. ISENTROPIC ASCENT WILL CONTINUE THIS MORNING...WITH SHORT TERM GUIDANCE HINTING AT THE POSSIBILITY FOR FURTHER PRECIP DEVELOPMENT ENTERING THE SOUTHWEST CWA JUST AFTER THE 12Z TIME FRAME. PREVIOUSLY DISCUSSED WARMING/WARM WEDGE STILL ANTICIPATED HERE THIS MORNING AND COULD INITIALLY BRING A WINTRY MIX BUT STAYING CONFINED TO THE SOUTHERN HALF OF THE CWA...PRIMARILY SOUTH OF THE I80 CORRIDOR. IF ANYTHING WERE TO OCCUR DURING THIS TIME FRAME...ANTICIPATE IT TO BE ON THE LIGHTER SIDE WITH THE PREVIOUSLY MENTIONED DRIER AIR STILL NEEDING TO BE OVERCOME. NONETHELESS...WITH AN ANTICIPATED SLOWING TREND WITH THE EVOLUTION OF TODAY`S SYSTEM...THIS WINTRY MIX COULD BE MORE PREVALENT THAN PREVIOUSLY THOUGHT TO START THE PERIOD. SO HAVE INCLUDED CHANCE ZR/IP IN THE GRIDS THROUGH 15Z. CAN MAKE OUT TWO SEPARATE PIECES OF STRONG ENERGY TRAVERSING THE MID LEVEL FLOW...NOW WITH ALL GUIDANCE IN STRONG AGREEMENT WITH THE EVOLUTION OF THIS ENERGY AS IT APPROACHES THE REGION. ABOUT THE ONLY DIFFERENCE AT THIS TIME IS SOME SLIGHT TIMING DIFFERENCES WITH THE APPROACH OF THE BETTER FORCING/PRECIP LATER TODAY. A CONTINUED SLOWER TREND HAS BEEN THE PREFERRED TREND HERE THIS MORNING...AND HAVE DELAYED HIGHEST POPS TODAY. ALTHOUGH DID NOT OVERLY STRAY TOO MUCH WITH THE PREVIOUSLY MENTIONED ISENTROPIC ASCENT AND POTENTIAL PRECIP OUT AHEAD OF IT. HAVE CONTINUED THE MENTION IN THE GRIDS FOR A MIX OF SLEET FOR LATER IN THE MORNING...MAINLY FOR THE SOUTHERN TIER OF COUNTIES. ALTHOUGH THERMAL PROFILES WOULD BE SUPPORTIVE OF THIS WINTRY MIX CONTINUING...HAVE LIMITED MENTION OF THIS MIX AS BETTER FORCING SHOULD BE ARRIVING DURING THIS TIME. WHATEVER LINGERING WARM WEDGE IN THE COLUMN WILL QUICKLY COOL THE COLUMN TO THE WET BULB AS STRONG DYNAMIC FORCING ARRIVES...WITH ANY MIX QUICKLY CHANGING OVER TO ALL SNOW. ONCE AGAIN...ALL GUIDANCE POINTING AT SIGNIFICANT SNOWFALL RATES BEGINNING AT SOON AS LATE MORNING FOR THE WESTERN CWA. TWO PIECES OF ENERGY WILL PHASE TOGETHER BY EARLY AFTERNOON...WITH THIS MID/UPPER LEVEL TROUGH BECOMING NEGATIVELY TILTED. AS THIS OCCURS...ATTENDANT LOW TO DEEPEN AS IT MOVES THROUGH CENTRAL ILLINOIS WITH 850MB LOW REALLY BEGINNING TO TAKE SHAPE. STRONG DYNAMICAL FORCING ASSOCIATED WITH THIS MID LEVEL TROUGH AND SIGNIFICANT HEIGHT FALLS WILL ALLOW FORCING TO SWING THROUGH THE CWA BY LATE MORNING INTO THE EARLY AFTERNOON. ASSOCIATED FRONTOGENETICAL FORCING WILL LIKEWISE PUSH EAST THROUGH THE AREA THIS AFTERNOON...WITH THE PRESENCE OF NEGATIVE EPV. THIS PRESENCE OF BOTH SLANTWISE AND UPRIGHT MOTIONS ARE LEADING FOR SOME REALLY IMPRESSIVE VERTICAL MOTION...WITH FORECAST OMEGA AMONG ALL GUIDANCE SOME OF THE HIGHEST IVE OBSERVED IN SOME TIME. THE STRONGEST VERTICAL MOTIONS ARE EXPECTED TO PUSH EAST TO WEST ACROSS THE CWA INTO THE EARLY AFTERNOON TIME FRAME AND CONTINUING THROUGH MID/LATE AFTERNOON...WITH FORCING CENTERED RIGHT IN THE MIDDLE OF THE CWA. ALTHOUGH CURRENT FORECAST SNOW TOTALS ARE THE HIGHEST IN THESE LOCATIONS...TOTALS DONT STRAY TOO MUCH FROM THE AMOUNTS ACROSS THE REMAINING CWA. THIS IS IN DUE TO PART TO HOW UNSTABLE THIS SYSTEM WILL BE...INCLUDING CONVECTIVE INSTABILITY. BOTH NAM/GFS SHOWING IMPRESSIVE MUCAPE TO PUSH NORTHEAST THROUGH THE CWA AS EARLY AS MID MORNING...AND THE BEGINNING STAGES OF THIS CAN ALREADY BE OBSERVED TO OUR WEST/SOUTHWEST WITH LATEST RAP ANALYSIS DEPICTING 100-200 J/KG OVER IOWA/MISSOURI/KANSAS. WITH SREF GUIDANCE INDICATING HIGH PROBABILITIES OF AT LEAST 50-100 J/KG OF MUCAPE TO MOVE OVERHEAD LATER TODAY...FEEL THAT THE NAM/GFS SOLUTION OF 100 TO ALMOST 300 J/KG IS NOT OF THE QUESTION. THE PRESENCE OF THIS STRONG FORCING...STRONG INSTABILITY AND ABUNDANCE OF MOISTURE NOT ONLY LIKELY BEING PRESENT BUT ALSO COMING TOGETHER...HAS STEERED THE FORECAST SIGNIFICANTLY MORE PESSIMISTIC THIS MORNING. HEAVIEST SNOW...WHICH WILL FALL WITH HIGH INTENSITIES AND POSSIBLY AT A RATE OF TWO TO THREE INCHES PER HOUR AT TIMES SHOULD ARRIVE THE FAR WESTERN CWA BY MID/LATE MORNING...AND THEN SPREADING EAST THROUGH THE REMAINING CWA BY EARLY AFTERNOON. EXPECT THESE HIGH SNOWFALL INTENSITIES THROUGH MID TO LATE AFTERNOON...AND POSSIBLY CONTINUE INTO THE EARLY EVENING FOR THE EASTERN THIRD OF THE CWA. THIS HEAVY SNOW WILL QUICKLY ACCUMULATE ON ROADS WITH NEAR VISIBILITY LIKELY UNDER THIS HEAVY SNOW...CREATING VERY HAZARDOUS CONDITIONS. AS WAS MENTIONED PREVIOUSLY...THE HIGHEST TOTALS ARE IN THE CWA ALIGNED WITH THE BETTER FORCING...BUT FEEL THAT ANY LACKING FORCING WILL BE SUPPLEMENTED WITH THE CONVECTIVE NATURE OF THIS SYSTEM. CONVECTIVE ALLOWING MODELS INDICATE THE PRESENCE OF THUNDER BREAKING OUT BY EARLY AFTERNOON. ALTHOUGH GUIDANCE IS HINTING THAT THIS WILL BE MORE PREFERRED ACROSS THE SOUTHERN CWA...WITH GUIDANCE INDICATING INSTABILITY INTO SOUTHERN WISCONSIN...HAVE INCLUDED A CHANCE FOR THUNDER IN THE GRIDS FOR THE ENTIRE CWA. ITS THESE CONVECTIVE ELEMENTS WHICH COULD SUPPLEMENT HIGHER RATES AND RESULTANT SNOWFALL TOTALS. SO FOR THE WARNING ISSUED OVERNIGHT...WILL HAVE AREA WIDE 4 TO 8 INCHES WITH THE POSSIBILITY OF SLIGHTLY HIGHER AMOUNTS NEAR 10 INCHES. IF THESE CONVECTIVE ELEMENTS WERE TO MATERIALIZE...THEN AREAS DEFINITELY COULD OBSERVE THESE HIGHER AMOUNTS. ALSO...ITS POSSIBLE THAT THESE AMOUNTS COULD BE OBSERVED IN A 4-6 HOUR WINDOW. HAVE THE WARNING ENDING EARLY THIS EVENING FOR THE WESTERN CWA AND THEN AT 3Z LATER THIS EVENING FOR THE EASTERN CWA. IF LATER GUIDANCE THIS MORNING CONTINUES TO SUPPORT CURRENT THINKING...SITUATION FORECAST TO UNFOLD LATER THIS AFTERNOON WILL DEFINITELY BE SOMETHING TO NOT TAKE LIGHTLY. RODRIGUEZ LONG TERM (TUESDAY THROUGH SUNDAY)... FAST ON THE HEELS OF TODAY`S DEPARTING SYSTEM WILL BE ANOTHER NORTHERN STREAM SYSTEM TRACKING ACROSS SOUTHERN CANADA. VERY STRONG WARM AIR ADVECTION WILL BE UNDERWAY ALOFT TUES MORNING AND EVENTUALLY DEVELOPING AT THE SURFACE AS SOUTHERLY WINDS PICK UP. DEEP AND FRESHLY RELOADED SNOW COVER OVER THE AREA WILL UNDOUBTEDLY RETARD THE WARM UP...BUT STILL THINK TEMPS SHOULD MANAGE TO CLIMB ABOVE FREEZING MOST AREAS FOR THE FIRST TIME IN WEEKS TUES AFTERNOON. WEAK COLD FRONT MOVES THROUGH TUESDAY EVENING WITH LITTLE FANFARE AND BARELY TIME FOR MUCH COLD AIR TO SEEP SOUTHWARD BEFORE WARM AIR ADVECTION BEGINS AGAIN LATER WEDNESDAY IN ADVANCE OF LATE WEDNESDAY NIGHT INTO THURSDAY`S WELL ADVERTISED BIG HULLABALOO. NOT SURPRISINGLY GIVEN THE COMPLEXITY OF THE PATTERN AND DEALING WITH PHASING ISSUES...MODELS HAVE FLOPPED BACK FROM THEIR PREVIOUS FLIP WITH MORE EMPHASIS ON A STRENGTHENING SOUTHERN LOW LIFTING NORTHEAST INTO THE GREAT LAKES. STILL SOME DIFFERENCES IN STRENGTH AND EXACT TRACK...BUT ECMWF/GFS NOW AGREE ON TAKING A SFC LOW OVER NORTHERN MISSOURI 18Z THURS NORTHEAST TO THE UPPER GREAT LAKES BY THURSDAY NIGHT...WITH CONSIDERABLE DEEPEN OF THE LOW ALONG THE WAY. ECMWF AND 06Z NAM ARE STRONGER AND A BIT FARTHER NORTHWEST...BUT NAM/GFS/ECMWF ALL HAVE THE SAME GENERAL IDEA. FIRST FORECAST ISSUE WILL BE WEDNESDAY NIGHT AS INITIAL BATCH OF WAA PRECIP BREAKS OUT AND LIFTS NORTH ACROSS THE AREA. MODEL QPF REMAINS FAIRLY HIGH AND WITH SOME ELEVATED INSTABILITY ALSO EVIDENT IN THE MODELS...CERTAINLY ENOUGH TO WARRANT A CONTINUED SLIGHT CHANCE MENTION OF THUNDERSTORMS. THE BIGGEST PROBLEM WED NIGHT WILL BE HOW FAST THE 2M TEMPS WARM UP. WHILE VERY STRONG WAA WILL BE TAKING PLACE ALOFT...INITIALLY EASTERLY WINDS OVER THE AREA AND DEEP SNOW PACK COULD ALLOW FOR A RATHER PROLONGED PERIOD OF FREEZING RAIN AND AN ICING THREAT DEPENDING ON SFC TEMPS. MANY OF THE MODEL SUGGEST A SURGE OF WARM LATE WEDNESDAY NIGHT...ESPECIALLY SOUTHERN CWA...BUT ITS GOING TO BE CLOSE. ONLY A MATTER OF A COUPLE DEGREES COULD MEAN THE DIFFERENCE BETWEEN A SIGNIFICANT ICING PROBLEM AND ALL RAIN AND THIS FAR OUT IT REALLY IS ANYONE`S GUESS WHAT SIDE OF 32F ANY ONE GIVEN AREA WILL END UP ON AS THE RAIN FALLS. CERTAINLY FARTHER NORTH WOULD STAND THE BETTER CHANCE OF FREEZING RAIN...BUT THE ICING POTENTIAL CANNOT BE RULED OUT EVEN OVER SOUTHERN PORTIONS OF THE CWA. THIS LATEST SWING IN THE MODELS TOWARD A MORE AMPLIFIED SOUTHERN LOW TRACKING NORTH IS BAD NEWS FOR IN THE HYDROLOGY DEPARTMENT. WHILE NOT AS HORRIFYING AS THE NIGHTMARE SCENARIO THE ECMWF HAD BEEN PAINTING A COUPLE DAYS AGO WITH 50 AND NEAR 60F DEWPOINTS TO THE WISCONSIN LINE...THE LATEST GUIDANCE DOES DRAG THE 40F ISODROSOTHERM FAR NORTH INTO THE AREA ON THURSDAY...WITH EVEN SOME 50F DEWPOINTS FAR SOUTHERN CWA. THE HIGHER THE DEWPOINTS THE MORE RAPID THE SNOW MELT WILL BE AND THE MORE OF A PROBLEM ANY MODERATE TO HEAVY RAIN THAT FALLS WILL POSE THURSDAY. TEMPS LOOK TO CLIMB SAFELY ABOVE FREEZING THURS AM EVEN NORTH TO THE WI BORDER ENDING THE FRZ RAIN THREAT...BUT WITH PWATS PROGGED TO CLIMB TO OVER AN INCH (200-250% OF NORMAL) THURSDAY THE POTENTIAL WILL EXIST FOR HEAVY RAINFALL. HAVE ALREADY BEEN HARPING ON ALL THE HYDRO CONCERNS IN THE ESF ISSUED FRIDAY AND UPDATED OVER THE WEEKEND AND REALLY NO BIG CHANGES IN THINKING AT THIS POINT OTHER THAN TO SAY THE FLOOD POTENTIAL IS LOOKING MORE OMINOUS THAN IT DID 24 HOURS AGO. STRONG COLD FRONT LOOKS TO SWEEP THROUGH THURSDAY EVENING BRINGING AN END TO THE RAIN AND POSSIBLE THUNDERSTORMS AND ALLOWING DRIER AND COLDER AIR TO FILTER INTO THE REGION. WHILE COLDER AIR FILTERS IN FOR THE WEEKEND WITH MEDIUM RANGE MODELS SUGGESTING ONE OR TWO SYSTEM COULD AFFECT THE REGION WITH WHAT WOULD PROBABLY BE SOME SNOWFALL. TIMING AND TRACK OF THESE LOWER AMPLITUDE WAVES ARE ALL OVER THE PLACE IN THE MODELS SO ONLY CARRYING LOW CHANCES POPS FOR NOW. IZZI && .HYDROLOGY... 330 AM CST LATEST MODEL GUIDANCE DOES LOOK MORE WORRISOME THAN IT DID 24 HOURS AGO REGARDING THE FLOOD POTENTIAL THURSDAY...POSSIBLY LINGERING INTO THE WEEKEND. MORE DETAIL METEOROLOGICAL DISCUSSION IS ABOVE. NO CHANGES REALLY TO THE PREVIOUS HYDROLOGICAL DISCUSSION OTHER THAN SLIGHTLY MORE SNOW AND SNOW WATER EQUIVALENT IS EXPECTED TO BE IN PLACE AFTER TODAY`S SNOW SYSTEM. WILL FRESHEN UP THE ESF AGAIN THIS MORNING BUT NOT PLANNING ANY BIG CHANGES. && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 12Z... * OCNL SNOW/IFR COULD DEVELOP WITH INITIAL WAVES OF SNOW MID-LATE MORNING * HEAVY SNOW TO DEVELOP EARLY-MID AFTERNOON WITH OCNL VSBY BETWEEN 1/16SM AND 1/4SM EXPECTED * SLIGHT CHANCE OF THUNDERSTORM (THUNDERSNOW) IN THE MID-LATE AFTERNOON * STRONG SOUTHEAST WINDS DEVELOP DURING MORNING WITH GUSTS TO AROUND 25KT EXPECTED...DIMINISHING AS HEAVY SNOW STARTS * QUICK IMPROVEMENT TO CIGS/VSBY AS SNOW ENDS EARLY THIS EVENING IZZI //DISCUSSION...UPDATED 12Z... A SHORT LIVED BUT INTENSE SNOW STORM WILL AFFECT THE AREA TODAY. RADAR ECHOS OVER DOWNSTATE ILLINOIS ARE INITIALLY EVAPORATING BEFORE REACHING THE GROUND...BUT SNOW COULD BEGIN TO PENETRATE THE LOW LEVEL DRY AIR AS EARLY AS MID MORNING...BUT MORE LIKELY BY LATE MORNING AND DEFINITELY BY EARLY AFTERNOON. MOST INTENSE SNOWFALL STILL LOOKS TO BE FOCUSED ON THE 19-23Z TIME FRAME FOR CHICAGO AND ALL INDICATIONS ARE THAT VSBY WILL DROP AT TIMES TO AT LEAST 1/4SM IF NOT LOWER WITH EVEN SOME THREAT OF +TSSN. SNOWFALL RATES COULD EXCEED 2 INCHES PER HOUR AT TIMES. STRONG SOUTHEAST WINDS THIS MORNING WILL DECREASE IN INTENSITY SOME AS THE SNOW PEAKS THIS AFTERNOON...BUT DIRECTION LIKELY TO REMAIN SE THROUGH MOST IF NOT ALL OF THE DURATION OF THE ACCUMULATING SNOW. INVERTED TROUGH SHOULD MOVE THROUGH THIS EVENING RESULTING IN WIND SHIFT TO WEST AND A QUICK WINDING DOWN OF THE SNOWFALL. IZZI //ORD AND MDW CONFIDENCE...UPDATED 12Z... * LOW-MEDIUM CONFIDENCE IN SNOW POTENTIAL MID-LATE MORNING * HIGH CONFIDENCE IN ONSET TIME OF MOD-HVY SNOW +/- AN HOUR OR SO * MEDIUM CONFIDENCE IN OCNL VSBY 1/4SM OR LOWER WITH ACCUMULATION RATES OF 1"/HOUR OR GREATER * MEDIUM-HIGH CONFIDENCE ON END TIME OF SNOW MONDAY EVENING +/- AN HOUR OR SO * HIGH CONFIDENCE IN REMAINDER OF FORECAST ELEMENTS IZZI //OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z... TUESDAY NIGHT THROUGH WEDNESDAY...PREDOMINANTLY VFR. WEDNESDAY NIGHT...RAIN OR FZRA DEVELOPING. THURSDAY..RAIN/FOG/IFR LIKELY. FZRA POSSIBLE IN THE MORNING. FRIDAY...VFR PROBABLE. SATURDAY AND SUNDAY...SOME POTENTIAL FOR SNOW. IZZI && .MARINE... 324 AM CST HAVE HOISTED A GALE WARNING FOR A LARGE PORTION OF CENTRAL LAKE MICHIGAN FOR TODAY. THE DEEPER SFC LOW IN THE MODELS SHOULD RESULT IN A PERIOD OF SOUTHEAST GALES THIS MORNING INTO THE EARLY AFTERNOON BEFORE THE BAGGIER PRESSURE GRADIENT APPROACHES THE LAKE ASSOCIATED WITH THE INVERTED TROUGH NORTH OF THE LOW TRACKING ACROSS DOWNSTATE IL AND IN. BRIEF SHOT OF WESTERLY WINDS TONIGHT IN THE WAKE OF THE TROUGH AND DEPARTING LOW BEFORE SOUTHERLY WINDS BEGIN TO REALLY CRANK UP AGAIN ON TUESDAY AS ANOTHER STRONG LOW TRACK EAST ACROSS THE SOUTHERN CANADIAN PRAIRIES. COULD BE BORDERLINE SOUTHERLY GALES ON TUESDAY AFTERNOON AS WELL...BUT FOR NOW JUST STUCK WITH OCNL GALE WORDING IN THE GLF AND WILL LET NEXT SHIFT GET ANOTHER LOOK BEFORE DECIDING ON POSSIBLE GALE HEADLINES FOR TUESDAY. IZZI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011- ILZ012-ILZ019-ILZ020-ILZ021-ILZ032-ILZ039 UNTIL 6 PM MONDAY. WINTER STORM WARNING...ILZ006-ILZ013-ILZ014-ILZ022-ILZ023- ILZ033...9 AM MONDAY TO 9 PM MONDAY. IN...WINTER STORM WARNING...INZ001-INZ002-INZ010-INZ011-INZ019...9 AM MONDAY TO 9 PM MONDAY. LM...GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ868-LMZ870-LMZ872-LMZ874-LMZ876 UNTIL 3 PM MONDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 PM MONDAY. && $$ 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
NWS CHICAGO/ROMEOVILLE IL
409 AM CST MON FEB 17 2014 .DISCUSSION... 330 AM CST SHORT TERM (THROUGH TONIGHT)... MAIN CONCERNS ARE WITH INCREASED POTENTIAL FOR A PERIOD OF HEAVY SNOW THIS AFTERNOON FOR THE ENTIRE CWA WHICH COULD HAVE SIGNIFICANT IMPACTS WITH WHITE OUT CONDITIONS UNDER POSSIBLE TWO TO THREE INCH PER HOUR SNOWFALL RATES SOME OF WHICH COULD FALL UNDER CONVECTIVE ELEMENTS...WITH AREA WIDE 4 TO 8 INCHES LIKELY AND SOME ISOLATED AMOUNTS NEAR 10 INCHES DEFINITELY NOT OUT OF THE QUESTION. IMPRESSIVE STRONG STORM ANTICIPATED TO TAKE SHAPE OVER THE AREA LATER TODAY CAN BE OBSERVED ON SATELLITE IMAGERY...WITH MID/UPPER LEVEL TROUGH CURRENTLY PUSHING EAST THROUGH THE NORTHERN PLAINS. OUT AHEAD OF THIS SYSTEM...LATEST RAP ANALYSIS DEPICTING STRONG ISENTROPIC ASCENT OCCURRING ACROSS THE ENTIRE REGION INCLUDING LOCALLY OVER THE CWA. THIS HAS RESULTED IN PERSISTENT MID/HIGH LEVEL CLOUD COVER TO STREAM OUT AHEAD OF THIS SYSTEM...WITH CURRENT RADAR IMAGERY LIGHTING UP WITH SOME DECENT RETURNS. ALTHOUGH RATHER DRY AIR IN PLACE HAS LIMITED ANY PRECIP TO REACH THE SURFACE AND ANTICIPATE FOR THIS TO FURTHER BE THE CASE OVER THE NEXT COUPLE OF HOURS. WHAT COULD BE EXPECTED IN THE NEAR TERM ARE SOME ISOLATED FLURRIES PRIMARILY OVER THE NORTHWEST HALF OF THE CWA...WITH RFD CURRENTLY REPORTING 9 MILES IN LIGHT SNOW. ISENTROPIC ASCENT WILL CONTINUE THIS MORNING...WITH SHORT TERM GUIDANCE HINTING AT THE POSSIBILITY FOR FURTHER PRECIP DEVELOPMENT ENTERING THE SOUTHWEST CWA JUST AFTER THE 12Z TIME FRAME. PREVIOUSLY DISCUSSED WARMING/WARM WEDGE STILL ANTICIPATED HERE THIS MORNING AND COULD INITIALLY BRING A WINTRY MIX BUT STAYING CONFINED TO THE SOUTHERN HALF OF THE CWA...PRIMARILY SOUTH OF THE I80 CORRIDOR. IF ANYTHING WERE TO OCCUR DURING THIS TIME FRAME...ANTICIPATE IT TO BE ON THE LIGHTER SIDE WITH THE PREVIOUSLY MENTIONED DRIER AIR STILL NEEDING TO BE OVERCOME. NONETHELESS...WITH AN ANTICIPATED SLOWING TREND WITH THE EVOLUTION OF TODAY`S SYSTEM...THIS WINTRY MIX COULD BE MORE PREVALENT THAN PREVIOUSLY THOUGHT TO START THE PERIOD. SO HAVE INCLUDED CHANCE ZR/IP IN THE GRIDS THROUGH 15Z. CAN MAKE OUT TWO SEPARATE PIECES OF STRONG ENERGY TRAVERSING THE MID LEVEL FLOW...NOW WITH ALL GUIDANCE IN STRONG AGREEMENT WITH THE EVOLUTION OF THIS ENERGY AS IT APPROACHES THE REGION. ABOUT THE ONLY DIFFERENCE AT THIS TIME IS SOME SLIGHT TIMING DIFFERENCES WITH THE APPROACH OF THE BETTER FORCING/PRECIP LATER TODAY. A CONTINUED SLOWER TREND HAS BEEN THE PREFERRED TREND HERE THIS MORNING...AND HAVE DELAYED HIGHEST POPS TODAY. ALTHOUGH DID NOT OVERLY STRAY TOO MUCH WITH THE PREVIOUSLY MENTIONED ISENTROPIC ASCENT AND POTENTIAL PRECIP OUT AHEAD OF IT. HAVE CONTINUED THE MENTION IN THE GRIDS FOR A MIX OF SLEET FOR LATER IN THE MORNING...MAINLY FOR THE SOUTHERN TIER OF COUNTIES. ALTHOUGH THERMAL PROFILES WOULD BE SUPPORTIVE OF THIS WINTRY MIX CONTINUING...HAVE LIMITED MENTION OF THIS MIX AS BETTER FORCING SHOULD BE ARRIVING DURING THIS TIME. WHATEVER LINGERING WARM WEDGE IN THE COLUMN WILL QUICKLY COOL THE COLUMN TO THE WET BULB AS STRONG DYNAMIC FORCING ARRIVES...WITH ANY MIX QUICKLY CHANGING OVER TO ALL SNOW. ONCE AGAIN...ALL GUIDANCE POINTING AT SIGNIFICANT SNOWFALL RATES BEGINNING AT SOON AS LATE MORNING FOR THE WESTERN CWA. TWO PIECES OF ENERGY WILL PHASE TOGETHER BY EARLY AFTERNOON...WITH THIS MID/UPPER LEVEL TROUGH BECOMING NEGATIVELY TILTED. AS THIS OCCURS...ATTENDANT LOW TO DEEPEN AS IT MOVES THROUGH CENTRAL ILLINOIS WITH 850MB LOW REALLY BEGINNING TO TAKE SHAPE. STRONG DYNAMICAL FORCING ASSOCIATED WITH THIS MID LEVEL TROUGH AND SIGNIFICANT HEIGHT FALLS WILL ALLOW FORCING TO SWING THROUGH THE CWA BY LATE MORNING INTO THE EARLY AFTERNOON. ASSOCIATED FRONTOGENETICAL FORCING WILL LIKEWISE PUSH EAST THROUGH THE AREA THIS AFTERNOON...WITH THE PRESENCE OF NEGATIVE EPV. THIS PRESENCE OF BOTH SLANTWISE AND UPRIGHT MOTIONS ARE LEADING FOR SOME REALLY IMPRESSIVE VERTICAL MOTION...WITH FORECAST OMEGA AMONG ALL GUIDANCE SOME OF THE HIGHEST IVE OBSERVED IN SOME TIME. THE STRONGEST VERTICAL MOTIONS ARE EXPECTED TO PUSH EAST TO WEST ACROSS THE CWA INTO THE EARLY AFTERNOON TIME FRAME AND CONTINUING THROUGH MID/LATE AFTERNOON...WITH FORCING CENTERED RIGHT IN THE MIDDLE OF THE CWA. ALTHOUGH CURRENT FORECAST SNOW TOTALS ARE THE HIGHEST IN THESE LOCATIONS...TOTALS DONT STRAY TOO MUCH FROM THE AMOUNTS ACROSS THE REMAINING CWA. THIS IS IN DUE TO PART TO HOW UNSTABLE THIS SYSTEM WILL BE...INCLUDING CONVECTIVE INSTABILITY. BOTH NAM/GFS SHOWING IMPRESSIVE MUCAPE TO PUSH NORTHEAST THROUGH THE CWA AS EARLY AS MID MORNING...AND THE BEGINNING STAGES OF THIS CAN ALREADY BE OBSERVED TO OUR WEST/SOUTHWEST WITH LATEST RAP ANALYSIS DEPICTING 100-200 J/KG OVER IOWA/MISSOURI/KANSAS. WITH SREF GUIDANCE INDICATING HIGH PROBABILITIES OF AT LEAST 50-100 J/KG OF MUCAPE TO MOVE OVERHEAD LATER TODAY...FEEL THAT THE NAM/GFS SOLUTION OF 100 TO ALMOST 300 J/KG IS NOT OF THE QUESTION. THE PRESENCE OF THIS STRONG FORCING...STRONG INSTABILITY AND ABUNDANCE OF MOISTURE NOT ONLY LIKELY BEING PRESENT BUT ALSO COMING TOGETHER...HAS STEERED THE FORECAST SIGNIFICANTLY MORE PESSIMISTIC THIS MORNING. HEAVIEST SNOW...WHICH WILL FALL WITH HIGH INTENSITIES AND POSSIBLY AT A RATE OF TWO TO THREE INCHES PER HOUR AT TIMES SHOULD ARRIVE THE FAR WESTERN CWA BY MID/LATE MORNING...AND THEN SPREADING EAST THROUGH THE REMAINING CWA BY EARLY AFTERNOON. EXPECT THESE HIGH SNOWFALL INTENSITIES THROUGH MID TO LATE AFTERNOON...AND POSSIBLY CONTINUE INTO THE EARLY EVENING FOR THE EASTERN THIRD OF THE CWA. THIS HEAVY SNOW WILL QUICKLY ACCUMULATE ON ROADS WITH NEAR VISIBILITY LIKELY UNDER THIS HEAVY SNOW...CREATING VERY HAZARDOUS CONDITIONS. AS WAS MENTIONED PREVIOUSLY...THE HIGHEST TOTALS ARE IN THE CWA ALIGNED WITH THE BETTER FORCING...BUT FEEL THAT ANY LACKING FORCING WILL BE SUPPLEMENTED WITH THE CONVECTIVE NATURE OF THIS SYSTEM. CONVECTIVE ALLOWING MODELS INDICATE THE PRESENCE OF THUNDER BREAKING OUT BY EARLY AFTERNOON. ALTHOUGH GUIDANCE IS HINTING THAT THIS WILL BE MORE PREFERRED ACROSS THE SOUTHERN CWA...WITH GUIDANCE INDICATING INSTABILITY INTO SOUTHERN WISCONSIN...HAVE INCLUDED A CHANCE FOR THUNDER IN THE GRIDS FOR THE ENTIRE CWA. ITS THESE CONVECTIVE ELEMENTS WHICH COULD SUPPLEMENT HIGHER RATES AND RESULTANT SNOWFALL TOTALS. SO FOR THE WARNING ISSUED OVERNIGHT...WILL HAVE AREA WIDE 4 TO 8 INCHES WITH THE POSSIBILITY OF SLIGHTLY HIGHER AMOUNTS NEAR 10 INCHES. IF THESE CONVECTIVE ELEMENTS WERE TO MATERIALIZE...THEN AREAS DEFINITELY COULD OBSERVE THESE HIGHER AMOUNTS. ALSO...ITS POSSIBLE THAT THESE AMOUNTS COULD BE OBSERVED IN A 4-6 HOUR WINDOW. HAVE THE WARNING ENDING EARLY THIS EVENING FOR THE WESTERN CWA AND THEN AT 3Z LATER THIS EVENING FOR THE EASTERN CWA. IF LATER GUIDANCE THIS MORNING CONTINUES TO SUPPORT CURRENT THINKING...SITUATION FORECAST TO UNFOLD LATER THIS AFTERNOON WILL DEFINITELY BE SOMETHING TO NOT TAKE LIGHTLY. RODRIGUEZ LONG TERM (TUESDAY THROUGH SUNDAY)... FAST ON THE HEELS OF TODAY`S DEPARTING SYSTEM WILL BE ANOTHER NORTHERN STREAM SYSTEM TRACKING ACROSS SOUTHERN CANADA. VERY STRONG WARM AIR ADVECTION WILL BE UNDERWAY ALOFT TUES MORNING AND EVENTUALLY DEVELOPING AT THE SURFACE AS SOUTHERLY WINDS PICK UP. DEEP AND FRESHLY RELOADED SNOW COVER OVER THE AREA WILL UNDOUBTEDLY RETARD THE WARM UP...BUT STILL THINK TEMPS SHOULD MANAGE TO CLIMB ABOVE FREEZING MOST AREAS FOR THE FIRST TIME IN WEEKS TUES AFTERNOON. WEAK COLD FRONT MOVES THROUGH TUESDAY EVENING WITH LITTLE FANFARE AND BARELY TIME FOR MUCH COLD AIR TO SEEP SOUTHWARD BEFORE WARM AIR ADVECTION BEGINS AGAIN LATER WEDNESDAY IN ADVANCE OF LATE WEDNESDAY NIGHT INTO THURSDAY`S WELL ADVERTISED BIG HULLABALOO. NOT SURPRISINGLY GIVEN THE COMPLEXITY OF THE PATTERN AND DEALING WITH PHASING ISSUES...MODELS HAVE FLOPPED BACK FROM THEIR PREVIOUS FLIP WITH MORE EMPHASIS ON A STRENGTHENING SOUTHERN LOW LIFTING NORTHEAST INTO THE GREAT LAKES. STILL SOME DIFFERENCES IN STRENGTH AND EXACT TRACK...BUT ECMWF/GFS NOW AGREE ON TAKING A SFC LOW OVER NORTHERN MISSOURI 18Z THURS NORTHEAST TO THE UPPER GREAT LAKES BY THURSDAY NIGHT...WITH CONSIDERABLE DEEPEN OF THE LOW ALONG THE WAY. ECMWF AND 06Z NAM ARE STRONGER AND A BIT FARTHER NORTHWEST...BUT NAM/GFS/ECMWF ALL HAVE THE SAME GENERAL IDEA. FIRST FORECAST ISSUE WILL BE WEDNESDAY NIGHT AS INITIAL BATCH OF WAA PRECIP BREAKS OUT AND LIFTS NORTH ACROSS THE AREA. MODEL QPF REMAINS FAIRLY HIGH AND WITH SOME ELEVATED INSTABILITY ALSO EVIDENT IN THE MODELS...CERTAINLY ENOUGH TO WARRANT A CONTINUED SLIGHT CHANCE MENTION OF THUNDERSTORMS. THE BIGGEST PROBLEM WED NIGHT WILL BE HOW FAST THE 2M TEMPS WARM UP. WHILE VERY STRONG WAA WILL BE TAKING PLACE ALOFT...INITIALLY EASTERLY WINDS OVER THE AREA AND DEEP SNOW PACK COULD ALLOW FOR A RATHER PROLONGED PERIOD OF FREEZING RAIN AND AN ICING THREAT DEPENDING ON SFC TEMPS. MANY OF THE MODEL SUGGEST A SURGE OF WARM LATE WEDNESDAY NIGHT...ESPECIALLY SOUTHERN CWA...BUT ITS GOING TO BE CLOSE. ONLY A MATTER OF A COUPLE DEGREES COULD MEAN THE DIFFERENCE BETWEEN A SIGNIFICANT ICING PROBLEM AND ALL RAIN AND THIS FAR OUT IT REALLY IS ANYONE`S GUESS WHAT SIDE OF 32F ANY ONE GIVEN AREA WILL END UP ON AS THE RAIN FALLS. CERTAINLY FARTHER NORTH WOULD STAND THE BETTER CHANCE OF FREEZING RAIN...BUT THE ICING POTENTIAL CANNOT BE RULED OUT EVEN OVER SOUTHERN PORTIONS OF THE CWA. THIS LATEST SWING IN THE MODELS TOWARD A MORE AMPLIFIED SOUTHERN LOW TRACKING NORTH IS BAD NEWS FOR IN THE HYDROLOGY DEPARTMENT. WHILE NOT AS HORRIFYING AS THE NIGHTMARE SCENARIO THE ECMWF HAD BEEN PAINTING A COUPLE DAYS AGO WITH 50 AND NEAR 60F DEWPOINTS TO THE WISCONSIN LINE...THE LATEST GUIDANCE DOES DRAG THE 40F ISODROSOTHERM FAR NORTH INTO THE AREA ON THURSDAY...WITH EVEN SOME 50F DEWPOINTS FAR SOUTHERN CWA. THE HIGHER THE DEWPOINTS THE MORE RAPID THE SNOW MELT WILL BE AND THE MORE OF A PROBLEM ANY MODERATE TO HEAVY RAIN THAT FALLS WILL POSE THURSDAY. TEMPS LOOK TO CLIMB SAFELY ABOVE FREEZING THURS AM EVEN NORTH TO THE WI BORDER ENDING THE FRZ RAIN THREAT...BUT WITH PWATS PROGGED TO CLIMB TO OVER AN INCH (200-250% OF NORMAL) THURSDAY THE POTENTIAL WILL EXIST FOR HEAVY RAINFALL. HAVE ALREADY BEEN HARPING ON ALL THE HYDRO CONCERNS IN THE ESF ISSUED FRIDAY AND UPDATED OVER THE WEEKEND AND REALLY NO BIG CHANGES IN THINKING AT THIS POINT OTHER THAN TO SAY THE FLOOD POTENTIAL IS LOOKING MORE OMINOUS THAN IT DID 24 HOURS AGO. STRONG COLD FRONT LOOKS TO SWEEP THROUGH THURSDAY EVENING BRINGING AN END TO THE RAIN AND POSSIBLE THUNDERSTORMS AND ALLOWING DRIER AND COLDER AIR TO FILTER INTO THE REGION. WHILE COLDER AIR FILTERS IN FOR THE WEEKEND WITH MEDIUM RANGE MODELS SUGGESTING ONE OR TWO SYSTEM COULD AFFECT THE REGION WITH WHAT WOULD PROBABLY BE SOME SNOWFALL. TIMING AND TRACK OF THESE LOWER AMPLITUDE WAVES ARE ALL OVER THE PLACE IN THE MODELS SO ONLY CARRYING LOW CHANCES POPS FOR NOW. IZZI && .HYDROLOGY... 330 AM CST LATEST MODEL GUIDANCE DOES LOOK MORE WORRISOME THAN IT DID 24 HOURS AGO REGARDING THE FLOOD POTENTIAL THURSDAY...POSSIBLY LINGERING INTO THE WEEKEND. MORE DETAIL METEOROLOGICAL DISCUSSION IS ABOVE. NO CHANGES REALLY TO THE PREVIOUS HYDROLOGICAL DISCUSSION OTHER THAN SLIGHTLY MORE SNOW AND SNOW WATER EQUIVALENT IS EXPECTED TO BE IN PLACE AFTER TODAY`S SNOW SYSTEM. WILL FRESHEN UP THE ESF AGAIN THIS MORNING BUT NOT PLANNING ANY BIG CHANGES. && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * CHANCE FOR SNOW SHOWERS BY MID TO LATE MORNING * HEAVY SNOW TO DEVELOP EARLY-MID AFTERNOON WITH OCNL VSBY BETWEEN 1/16SM AND 1/4SM EXPECTED * SLIGHT CHANCE OF THUNDERSTORM (THUNDERSNOW) IN THE MID-LATE AFTERNOON * STRONG SOUTHEAST WINDS DEVELOP DURING MORNING WITH GUSTS TO AROUND 25KT EXPECTED...DIMINISHING AS HEAVY SNOW STARTS * QUICK IMPROVEMENT TO CIGS/VSBY AS SNOW ENDS EARLY THIS EVENING IZZI //DISCUSSION...UPDATED 09Z... ONLY NOTABLE CHANGE TO PREVIOUS TAFS WAS TO INCLUDE A TEMPO FOR LIGHT SNOW MID-LATE MORNING. LOW LEVELS REMAIN DRY BUT FAIRLY EXTENSIVE VIRGA (SOME RATHER INTENSE ECHOS) SHOWING UP ON RADAR AND AM CONCERNED THAT CONTINUED PRECIPITATING INTO THE DRY WILL MOISTEN THINGS UP ENOUGH FOR SNOW TO DEVELOP. HEAVIEST SNOW BY FAR IS EXPECTED TO BE THIS AFTERNOON...BUT WORRIED THAT THERE COULD STILL BE SOME PERIODIC IFR LIGHT SNOW MID-LATE MORNING AHEAD OF THE BIG HULLABALOO. IZZI UPDATED 06Z... LAKE EFFECT MVFR CIGS LIKELY TO PERSIST FOR AT LEAST A FEW MORE HOURS OVERNIGHT BEFORE PROBABLY BREAKING UP LATE. CONTINUE TO SEE SOME MODELS STARTING UP SNOW SHOWERS DURING THE MORNING HOURS MONDAY...WHICH IF IT WERE TO HAPPEN COULD RESULT IN A MUCH EARLIER ONSET TO IFR CONDITIONS THAN INDICATED IN THE CURRENT TAFS. HANDLING THIS WITH A VCSH IN THE TAFS AND WILL MONITOR RADAR/SATELLITE TRENDS THIS MORNING AND RE-ACCESS LATER. STRONG PRESSURE FALLS TO OUR WEST IN RESPONSE TO THE DEVELOPING LOW WILL RESULT IN A QUICK RAMP UP OF SOUTHEAST WINDS EARLY MONDAY MORNING WITH GUSTS OF 25-30KT EXPECTED BY MID-LATE MORNING. BIG STORY WILL BE THE INTENSE SNOW EXPECTED TO DEVELOP MONDAY AFTERNOON. ALL INDICATIONS ARE THAT 3 TO 6 HOUR LONG WINDOW OF MODERATE TO HEAVY SNOW WILL OCCUR MONDAY AFTERNOON. GETTING FAIRLY STRONG SIGNALS IN THE MODELS TO SUPPORT PERIODIC VERY HEAVY SNOWFALL WITH EVEN A SMALL CHANCE OF ISOLATED THUNDERSTORMS. WINDS WILL SUBSIDE AS SNOW BEGINS BUT WITH SNOWFALL RATES OF AT LEAST AN INCH PER HOUR LIKELY AND CRIPPLING RATES OF 2"+ PER HOUR POSSIBLE THE DECREASING WINDS WILL BE A BIT OF A MOOT POINT. CONDITIONS ARE LIKELY TO QUICKLY IMPROVE AS THE TROUGH MOVES THROUGH EARLY MONDAY EVENING. WINDS WILL SHIFT TO WESTERLY AND THERE WILL PROBABLY BE SEVERAL HOURS OF LINGER MVFR CIGS INTO THE EVENING HOURS. IZZI //ORD AND MDW CONFIDENCE...UPDATED 09Z... * LOW CONFIDENCE IN SNOW POTENTIAL BETWEEN 14-18Z THIS MORNING * HIGH CONFIDENCE IN ONSET TIME OF MOD-HVY SNOW +/- AN HOUR OR SO * MEDIUM CONFIDENCE IN OCNL VSBY 1/4SM OR LOWER WITH ACCUMULATION RATES OF 1"/HOUR OR GREATER * MEDIUM-HIGH CONFIDENCE ON END TIME OF SNOW MONDAY EVENING +/- AN HOUR OR SO * HIGH CONFIDENCE IN REMAINDER OF FORECAST ELEMENTS IZZI //OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z... TUESDAY AND WEDNESDAY...PREDOMINANTLY VFR. THURSDAY...RAIN/FOG/IFR LIKELY. FZRA POSSIBLE IN THE MORNING. FRIDAY...VFR PROBABLE. SATURDAY...CHANCE OF RA OR SN. MDB && .MARINE... 324 AM CST HAVE HOISTED A GALE WARNING FOR A LARGE PORTION OF CENTRAL LAKE MICHIGAN FOR TODAY. THE DEEPER SFC LOW IN THE MODELS SHOULD RESULT IN A PERIOD OF SOUTHEAST GALES THIS MORNING INTO THE EARLY AFTERNOON BEFORE THE BAGGIER PRESSURE GRADIENT APPROACHES THE LAKE ASSOCIATED WITH THE INVERTED TROUGH NORTH OF THE LOW TRACKING ACROSS DOWNSTATE IL AND IN. BRIEF SHOT OF WESTERLY WINDS TONIGHT IN THE WAKE OF THE TROUGH AND DEPARTING LOW BEFORE SOUTHERLY WINDS BEGIN TO REALLY CRANK UP AGAIN ON TUESDAY AS ANOTHER STRONG LOW TRACK EAST ACROSS THE SOUTHERN CANADIAN PRAIRIES. COULD BE BORDERLINE SOUTHERLY GALES ON TUESDAY AFTERNOON AS WELL...BUT FOR NOW JUST STUCK WITH OCNL GALE WORDING IN THE GLF AND WILL LET NEXT SHIFT GET ANOTHER LOOK BEFORE DECIDING ON POSSIBLE GALE HEADLINES FOR TUESDAY. IZZI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011- ILZ012-ILZ019-ILZ020-ILZ021-ILZ032-ILZ039 UNTIL 6 PM MONDAY. WINTER STORM WARNING...ILZ006-ILZ013-ILZ014-ILZ022-ILZ023- ILZ033...9 AM MONDAY TO 9 PM MONDAY. IN...WINTER STORM WARNING...INZ001-INZ002-INZ010-INZ011-INZ019...9 AM MONDAY TO 9 PM MONDAY. LM...GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ868-LMZ870-LMZ872-LMZ874-LMZ876...8 AM MONDAY TO 3 PM MONDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 PM MONDAY. && $$ 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
NWS NORTHERN INDIANA
550 AM EST MON FEB 17 2014 .SYNOPSIS... ISSUED AT 343 PM EST MON FEB 17 2014 A LOW PRESSURE SYSTEM OVER THE PLAINS WILL MOVE EAST THROUGH INDIANA THIS AFTERNOON AND EVENING...CAUSING A BAND OF MODERATE TO HEAVY SNOW TO PIVOT THROUGH THE AREA DURING THIS TIME. SOME SLEET AND FREEZING RAIN MAY MIX WITH THE SNOW ALONG AND SOUTH OF HIGHWAY 24 IN INDIANA AND OHIO. TOTAL SNOW ACCUMULATIONS ARE FORECAST TO RANGE BETWEEN 2 AND 6 INCHES ACROSS THE FORECAST AREA...HEAVIEST ACROSS NORTHERN AREAS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 343 AM EST MON FEB 17 2014 BURST OF MOD-HVY SNOW LATER THIS AFTN AND EVE / MIXED WITH SLEET SOUTH OF HWY 24 / THE PRIMARY FOCUS THIS PERIOD... MORNING WATER VAPOR IMAGERY SHOWS A WELL DEFINED PV ANOMALY NEAR THE NE/CO BORDER WITH ANOTHER NORTHERN STREAM UPPER WAVE EDGING TOWARD THE MT/ND BORDER. GUIDANCE NOW IN EXCELLENT AGREEMENT IN PHASING THESE WAVES AS THEY RIPPLE QUICKLY EAST WITH A CLOSED MID LVL CIRCULATION EVENTUALLY EMERGING OVER SOUTHERN LOWER MICHIGAN THIS EVENING. THIS STRONG UPPER TROUGH WILL SHIFT NEGATIVE AND DEEP WITH 1.5 PVU SFC NEAR 700 MB ONCE IT LIFTS INTO IL/IN LATER TODAY. ASSOCIATED DEEP PLUME OF UPWARD VERTICAL MOTION WITH VIGOROUS WAVE LOOKS TO LIFT ENE THROUGH THE LOCAL AREA LATER THIS AFTN/EVE WITH A 4-7 HOUR PERIOD OF ACCUMULATING SNOW ANTICIPATED. SNOWFALL RATES OF 1-2" PER HR POSSIBLE GIVEN VERY STRONG DYNAMICS AND LOW LEVEL MOISTURE TRANSPORT/CONVERGENCE WITHIN DEVELOPING TROWAL AS SFC REFLECTION DEEPENS NORTHEAST INTO NRN INDIANA/SE MI. XSECTIONS/SOUNDINGS IMPRESSIVE WITH STEEP MID LVL LAPSE RATES INTO ESPECIALLY SOUTHERN AREAS ALONG WITH A THIN LAYER WHERE THETA-E DECREASES WITH HEIGHT. GIVEN THIS CANNOT RULE OUT SOME THUNDER BUT COVERAGE AND CONFIDENCE OF OCCURRENCE REMAINS TOO LOW TO INCLUDE A THUNDER MENTION IN GRIDS. NORTHERLY TRACK OF THIS PHASED SYSTEM WILL ALLOW SOME WARMER AIR ALOFT TO WORK INTO AREAS SOUTH/ALONG THE HWY 24 CORRIDOR WHERE PRECIP MAY MIX WITH SLEET (AND LOWER CHC FOR FREEZING RAIN FAR SOUTH) TO START BEFORE DYNAMIC/EVAPORATIVE COOLING OVERWHELMS SUPPORTING A CHANGEOVER TO ALL SNOW. THIS SHOULD CUT DOWN ON SNOW TOTAL A BIT HERE...WITH HEAVIEST TOTALS EXPECTED ACROSS THE FAR NORTH WHERE PIVOT IS EXPECTED UNDER DEVELOPING 700 MB LOW TRACK. CURRENT EXPECTATIONS ARE FOR A QUICK 4-6" (LOCALIZED 6" PLUS AMOUNTS POSSIBLE) OF SNOW NORTHWEST OF HWY 24...3-5" ALONG HWY 24...AND 2-4" SOUTHEAST OF HWY 24. STRONG RISE FALL COUPLET OVERSPREADS THIS EVENING INTO THE EARLY OVERNIGHT HOURS WHICH MAY CREATE SOME BLOWING/DRIFTING SNOW FOR A TIME. AS FOR THE NEAR TERM (THIS MORNING INTO EARLY AFTN)...6-8 MB SFC 3 HR PRESSURE FALLS WILL ALLOW WINDS TO PICK UP AND GUST TO BTW 25-30 MPH LATER THIS MORNING. THIS MAY LEAD TO SOME BLOWING AND DRIFTING IN RURAL/OPEN AREAS. CHANCES FOR SNOW INCREASE WITH TIME AS 850-700 MB THETA-E GRADIENT SHIFTS EAST INTO WESTERN AREAS THIS MORNING. BAND OF SNOW TRYING TO GET STARTED ALONG THIS GRADIENT ACROSS SOUTHERN WI/NORTHERN IL AS OF THIS WRITING BUT LOSING THE BATTLE TO DRY SUB-CLOUD LAYER AT THIS TIME. RAP SATURATES OVER THE AREA WITH RELATIVE NARROW OF SNOW DEVELOPING OVER WESTERN ZONES BTW 15-18Z WHILE THE 06Z NAM SLOWER AFTER 18Z. OPTED FOR CHC POPS GIVEN THE UNCERTAINTY. && .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 343 AM EST MON FEB 17 2014 FOR TUESDAY...QUIET WEATHER IN STORE WITH DEPARTURE OF MONDAYS SNOW PRODUCER...AS SHORT WAVE UPPER RIDGING TRACKS ACROSS THE GREAT LAKES. MID/UPPER LEVEL PATTERN TO BE QUITE PROGRESSIVE THROUGH MID WEEK AS LOWER AMPLITUDE WAVE TRACKS ACROSS NORTHERN PLAINS/NORTHERN GREAT LAKES EVENTUALLY ALLOWING SFC TROUGH/COLD FRONT PASSAGE INTO THE AREA TUESDAY NIGHT/EARLY WEDNESDAY MORNING. LOW LEVEL HEIGHT GRADIENT SHOULD STEADILY STRENGTHEN ON TUESDAY IN ADVANCE OF THIS TROUGH WHICH SHOULD ALLOW FOR SOUTH WINDS TO INCREASE BY MIDDAY. CURRENTLY EXPECTING GUSTS UP TO AROUND 25 MPH WHICH COULD CREATE SOME DRIFTING CONCERNS EARLY TUESDAY AFTERNOON ACROSS OPEN AREAS FOR ESPECIALLY EAST TO WEST ORIENTED ROADWAYS. RELATIVELY LOWER SNOW TO LIQUID RATIOS AND SFC TEMPS WARMING TO ABOVE FREEZING IN THE AFTERNOON SHOULD TEND TO MITIGATE THIS CONCERN HOWEVER. THE RELATIVELY DRY AIR MASS IN PLACE SHOULD LIMIT ANY MEASURABLE PRECIP CHANCES IN ASSOCIATION WITH THE FRONT TUESDAY NIGHT...ALTHOUGH GIVEN MOISTURE PROFILES AND WEAK LIFT CANNOT COMPLETELY RULE OUT SOME VERY LIGHT PATCHY FREEZING DRIZZLE FOR A BRIEF TIME IN IMMEDIATE VICINITY OF THE FRONT. WEAK THERMAL TROUGH WILL BE IN PLACE ACROSS THE AREA FOR WEDNESDAY BEHIND THIS FRONT...WITH EVENTUAL ONSET OF STRONGER LOW LEVEL WAA AGAIN TOWARD WEDNESDAY EVENING AS LOW LEVEL ANTICYCLONE SHIFTS TO THE MID ATLANTIC STATES. PRESENCE OF LOW LEVEL THERMAL TROUGH AND VERY SHALLOW MIXED LAYER DEPTHS SHOULD RESULT IN HIGHS A DEGREE OR TWO LOWER THAN TUESDAY AFTERNOON...ALTHOUGH STILL INTO AT LEAST MID 30S MOST LOCATIONS. WITH DAYTIME TEMPS MARGINALLY ABOVE FREEZING AND NIGHTTIME TEMPS EXPECTED TO DROP BELOW FREEZING TUESDAY NIGHT/WEDNESDAY NIGHT...SNOWMELT WILL BE VERY GRADUAL AND NO SIGNIFICANT HYDROLOGIC IMPACTS ARE EXPECTED THROUGH MIDWEEK. CONCERN FOR THURSDAY WILL THEN SHIFT TO WARMING TREND AND POTENTIAL FOR SIGNIFICANT RAINFALL WHICH WILL LEAD TO INCREASED FLOOD POTENTIAL. BULK OF GUIDANCE HAS NOW SHIFTED BACK TO TREND OF SEVERAL DAYS AGO IN DEPICTING TWO DISTINCT EASTERN PACIFIC WAVES PHASING ACROSS THE UPPER MIDWEST/NORTHERN GREAT LAKES...AND PROMOTING STRONGER CYCLOGENESIS ACROSS THE WESTERN GREAT LAKES FOR THURSDAY. DETAILS STILL DIFFICULT TO PIN DOWN AT THIS POINT WITH HOW THESE WAVES WILL INTERACT AND EXTENT/TIMING OF LOW LEVEL DEEPENING...BUT HAVE SLIGHTLY TRENDED FORECAST TO THIS STRONGER EVOLUTION. STRONG LOW LEVEL THETAE ADVECTION/MOISTURE TRANSPORT TO RACE NORTHEASTWARD INTO THE LOCAL AREA BY THURSDAY MORNING WITH PTYPE CONCERNS LIKELY TO EXIST AT ONSET OF PRECIP. A BRIEF PERIOD OF -SN/-FZRA IS POSSIBLE THURSDAY MORNING BEFORE STRENGTH OF LOW LEVEL ADVECTION OVERWHELMS PROFILES AND SUPPORTS LIQUID PRECIP TYPE. AFTER THIS INITIAL WARM/MOIST ADVECTIVE SURGE THURSDAY...ITEM OF LOWER CONFIDENCE WILL BE POTENTIAL FOR ANY ADDITIONAL PRECIP INTO THURSDAY EVENING THAT MAY HAVE SOME CONVECTIVE NATURE DEPENDING ON EXACT EVOLUTION OF PATTERN. THIS WILL NEED TO BE WATCHED FOR POTENTIAL HIGHER RAINFALL AMOUNTS THAT WILL IMPACT FLOOD POTENTIAL...ESPECIALLY IN LIGHT OF SFC DEW POINTS LIKELY RISING INTO THE UPPER 30S TO LOWER 40S THAT WILL ACCELERATE SNOWMELT. LARGER SCALE FRONTAL FORCING MAY ALLOW RAIN TO PERSIST THROUGH MUCH OF THURSDAY NIGHT...ESPECIALLY ACROSS EASTERN HALF OF THE AREA. COLDER AIR TO ADVECT BACK INTO THE REGION FOR FRIDAY BEHIND THIS SYSTEM THAT MAY PROVIDE SOME BENEFIT TO RUNOFF FROM RECENT RAIN/MELTING SNOW. WILL CONTINUE WITH ESF THIS MORNING HIGHLIGHTING OVERALL POTENTIAL...BUT MUCH OF THIS WILL DEPEND ON EXACT RAINFALL AMOUNTS THURSDAY ALONG WITH HOW QUICKLY UPSTREAM SYSTEM PHASES WHICH WILL BE CRITICAL FOR TEMP/DEW PT TRENDS. PREDICTABILITY IN SMALLER SCALE WAVES IMPACTING THE AREA FOR THE WEEKEND STILL QUITE LOW AT THIS TIME...ALTHOUGH NEW 00Z GUIDANCE STILL SUPPORTS IDEA OF DEEPER MOISTURE SHUNTED WELL SOUTH OF THE AREA. HAVE CONTINUED PREVIOUS LOW CHANCE -SN/RA POPS FOR THE WEEKEND WITH A SERIES OF LOW LEVEL AMPLITUDE CLIPPER SYSTEMS POSSIBLE THROUGH THE EARLY PORTIONS OF NEXT WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 550 AM EST MON FEB 17 2014 MAINLY VFR THIS MORNING WITH PRIMARY FOCUS ON RAPIDLY DETERIORATING FLIGHT CONDITIONS WITH 4-6 HR PERIOD OF MODERATE/HEAVY SNOW LATE THIS AFTN AND EVE AS A VERY DYNAMIC/STRONG UPPER LEVEL SYSTEM LIFTS INTO THE AREA. OTHERWISE...IMPRESSIVE PRESSURE FALLS THROUGH EARLY AFTERNOON WILL RESULT IN A BREEZY DAY WITH SHALLOW MIXING GENERALLY HOLDING GUSTS TO LESS THAN 30 KNOTS BEFORE DIMINISHING LATE AFTN/EARLY EVE AS SFC LOW CENTER TRACKS INTO NORTHERN INDIANA. IMPROVING CONDITIONS ARE EXPECTED LATER TONIGHT AS SYSTEM LIFTS OUT OF THE AREA. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM EST TUESDAY FOR INZ006>009-017-018-025>027-032>034. WINTER WEATHER ADVISORY FROM NOON EST /11 AM CST/ TODAY TO 11 PM EST /10 PM CST/ THIS EVENING FOR INZ003>005-012>016-020- 022>024. MI...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM EST TUESDAY FOR MIZ079>081. WINTER WEATHER ADVISORY FROM NOON TODAY TO 11 PM EST THIS EVENING FOR MIZ077-078. OH...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 3 AM EST TUESDAY FOR OHZ001-002-004-005-015-016-024-025. LM...NONE. && $$ SYNOPSIS...JT SHORT TERM...STEINWEDEL LONG TERM...MARSILI AVIATION...STEINWEDEL VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS GOODLAND KS
333 AM MST MON FEB 17 2014 .SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT) ISSUED AT 314 AM MST MON FEB 17 2014 SHORT TERM FORECAST CONCERN IS THE POSSIBILITY OF PRECIPITATION LATE WEDNESDAY AND WEDNESDAY NIGHT. BREEZY NORTHWEST WINDS EARLY TODAY WILL WEAKEN THROUGH THE DAY AND TURN BACK TO THE SOUTHWEST AS A SURFACE TROUGH DEEPENS ALONG THE FRONT RANGE AND WESTERLY WINDS CONTINUE ALOFT. A WEAK TROUGH ALOFT MOVES ACROSS THE FORECAST AREA ON TUESDAY WITH A TROUGH REFLECTED AT THE SURFACE THAT WILL AGAIN SEE SOUTHWEST WINDS TURNING TO THE NORTHWEST AND BECOMING GUSTY DURING THE AFTERNOON. THERE WILL BE WEAK RIDGING A LOFT AHEAD OF THE NEXT TROUGH EXPECTED TO MOVE EAST OF THE ROCKIES WEDNESDAY NIGHT ALONG WITH A COLD FRONT THAT PUSHES THROUGH THE FORECAST AREA WEDNESDAY EVENING. ALONG AND BEHIND THE FRONT THERE IS A BAND OF PRECIPITATION THAT IS CONSISTENTLY SHOWING UP IN MODEL SOLUTIONS. THIS PRECIPITATION IS EXPECTED TO START OUT AS RAIN WEDNESDAY EVENING AND TRANSITION TO ALL SNOW AFTER MIDNIGHT WITH ONE INCH OR LESS OF TOTAL SNOW ACCUMULATIONS. .LONG TERM...(THURSDAY THROUGH SUNDAY) ISSUED AT 314 AM MST MON FEB 17 2014 UPPER LEVEL TROUGH WILL MOVE EASTWARD AS AN UPPER LEVEL SHORTWAVE TROUGH MOVES INTO THE HIGH PLAINS FOR THURSDAY. CENTRAL TROUGH AXIS LOOKS TO BE SOMEWHERE BETWEEN THE COLORADO FRONT RANGE AND OUR FORECAST AREA. STRONGEST JET AND VORT MAXES SHOULD REMAIN SOUTH OF THE TRI STATE AREA. A WEAK SHORTWAVE RIDGE WILL THEN MOVE INTO THE FORECAST AREA THURSDAY BEFORE DISSIPATING THURSDAY NIGHT. ANOTHER PUSH OF COLD AIR ALOFT WILL MOVE INTO THE REGION FRIDAY AS AN UPPER LEVEL TROUGH WILL PERSIST OVER THE AREA NEXT WEEKEND. SURFACE COLD FRONT SHOULD BE WELL THROUGH THE FORECAST AREA BY THURSDAY MORNING...HOWEVER SOME LINGERING LIGHT SNOW SHOWERS WILL BE POSSIBLE BEHIND THE FRONT. NO SIGNIFICANT SNOW ACCUMULATIONS WITH THIS SYSTEM ARE EXPECTED AT THIS TIME. THE REGION WILL RECEIVE A BRIEF BREAK IN WEATHER THURSDAY AFTERNOON AND EVENING AS A SMALL AREA OF SURFACE HIGH PRESSURE SLIDES INTO THE HIGH PLAINS. ANOTHER COLD FRONTAL PASSAGE WILL AFFECT THE AREA FRIDAY AFTERNOON...WHICH WILL BRING CHANCES FOR SOME WIDESPREAD LIGHT SNOW SHOWERS OVERNIGHT INTO SATURDAY MORNING. HIGH TEMPERATURES WILL DIP SLIGHTLY BELOW AVERAGE INTO THE UPPER 30S. WARMER AIR WILL APPROACH FROM THE SOUTH SUNDAY...BUT THE WARM FRONT DOES NOT LOOK TO PASS THROUGH THE AREA. HIGH TEMPERATURES WILL RETURN TO APPROXIMATELY NORMAL CONDITIONS IN THE MID 40S. THE SLOW MOVING BOUNDARY LOOKS TO SET UP THROUGH WEST CENTRAL KANSAS...WHICH MAY CAUSE SOME LIGHT PRECIPITATION ACROSS THE AREA MONDAY. 1000-500 MB THICKNESS INDICATES THAT THE FORECAST AREA WILL BE SPLIT...WITH CHANCES FOR LIGHT RAIN SHOWERS IN THE SOUTHERN HALF AND CHANCES FOR LIGHT SNOW SHOWERS IN THE NORTHERN HALF. HIGH TEMPERATURES SHOULD STAY IN THE LOW TO MID 40S. GUIDANCE SUGGESTS THE WARM FRONT WILL MAKE A FINAL PUSH THROUGH THE REGION BY MONDAY LATE AFTERNOON. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 928 PM MST SUN FEB 16 2014 VFR CONDITIONS WILL CONTINUE THROUGH THE TAF PERIOD. THE COLD FRONT HAS ALREADY MOVED THROUGH KGLD AND WINDS HAVE SHIFTED TO THE NORTHWEST...A LITTLE EARLIER THAN PREVIOUSLY THOUGHT. THE COLD FRONT WILL HAVE MOVED THROUGH KMCK BEFORE 06Z WITH NORTHWEST WINDS AROUND 15 KTS AFTER BRIEFLY HIGHER WIND SPEEDS AND GUSTS. BASED ON OBSERVATIONS AT KGLD AND UPSTREAM...DID NOT INCLUDE GUSTS IN FOR THE INITIAL PREVAILING GROUP AT EITHER TERMINAL. HOWEVER...BUFKIT RAP SOUNDINGS STILL INDICATE WINDS INCREASING OVERNIGHT WITH GUSTS AROUND 30 TO 35 KTS BETWEEN 06Z AND 12Z. SINCE THE RAP SEEMS TO BE CATCHING THE CURRENT CONDITIONS AND UPSTREAM SITES HAVE GUSTS AROUND 35 KTS...DECIDED TO GO WITH THIS FOR NOW. TOMORROW AFTERNOON WINDS WILL SHIFT AGAIN TO THE WEST- SOUTHWEST...WITH GUSTS AROUND 20 TO 25 KTS. WINDS SHOULD DIMINISH AROUND SUNSET...REMAINING SUSTAINED AROUND OR UNDER 10 KTS WITH NO GUSTS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...LOCKHART LONG TERM...99 AVIATION...ALW
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
727 AM EST MON FEB 17 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 522 AM EST MON FEB 17 2014 09Z WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL PATTERN ACROSS THE WEST AND CENTRAL CONUS WITH A MID/UPPER LEVEL TROUGH AND SEVERAL EMBEDDED SHRTWVS EMERGING FROM THE NRN ROCKIES INTO THE WRN PLAINS. WAA/ISENTROPIC LIFT AHEAD OF THIS SHORTWAVE TROUGH HAS ALLOWED MID-HIGH CLOUDS TO SPREAD INTO THE FCST AREA FM THE WEST. AS A RESULT...MUCH BELOW ZERO TEMPS FM LAST EVENING OVER CENTRAL AND EASTERN COUNTIES OF THE CWA HAVE BEGUN TO MODERATE ABV ZERO AT MANY LOCATIONS. SOME LIGHT SNOW IS ALSO NOW APPEARING ON RADAR AND SFC OBS OVER NCNTRL WI AND FAR WRN UPR MI. TODAY...MODELS IN GENERALLY GOOD AGREEMENT ON DEPICTION/MOVEMENT OF MAIN SHORTWAVE NOW OVER WRN NEBRASKA TRACKING IT AND ASSOC SFC LOW ESE THROUGH CNTRL ILLINOIS AND NRN INDIANA LATE AFTERNOON/EARLY EVENING. NORTHERN SHORTWAVE OVER THE DAKOTAS APPEARS TO BECOME MORE SHEARED OUT WITH TIME AS IT APPROACHES THE WRN LAKES LATE THIS AFTERNOON. THIS IS REFLECTED IN 700-300 MB LAYER Q-VECTORS WHICH SHOWS BEST CONV/LIFT GENERALLY PASSING SOUTH AND EAST OF THE FCST AREA THIS AFTERNOON. ALSO A LIMITING FACTOR FOR HEAVY SNOW TODAY OVER OUR AREA IS THE VERY DRY AIRMASS ALREADY IN PLACE AS NOTED ON 00Z GRB AND APX SOUNDINGS. CONSEQUENTLY..IT WILL TAKE LONGER FOR COLUMN TO MOISTEN FM ISENTROPIC ASCENT AS THUS WILL LIKELY LIMIT SNOW AMOUNTS SOMEWHAT. CONTINUED THE PREV FCST TREND OF GOING ON THE LOWER END OF MODEL GUIDANCE FOR QPF AMOUNTS RANGING FROM .15 INCH FAR EAST TO NEARLY .3 INCH NEAR MNM. USING COBB METHOD AVERAGED SLR VALUES AROUND 17:1...TOTAL SNOW AMOUNTS FROM THIS SYSTEM WILL LIKELY FALL INTO THE 3 TO 5 INCH RANGE ACROSS MUCH OF THE AREA...BUT FAR NE CWA MAY STRUGGLE TO REACH MINIMAL ADVISORY CRITERIA OF 3 INCHES DUE TO EFFECTS OF ATTENDANT DRY AIR DELAYING ARRIVAL OF PCPN UNTIL MAINLY AFTERNOON. SSE WINDS ARE EXPECTED TO INCREASE AND GUST NEAR 25 MPH AT TIMES BY LATE MORNING/AFTERNOON WHICH MAY CONTRIBUTE TO SOME BLSN BUT NOTHING OF GREAT SIGNIFICANCE. CONTINUED THE WINTER WEATHER ADVISORIES ACROSS THE AREA BUT GIVEN POTENTIAL LIMITING FACTORS MENTIONED ABOVE...LOWERED HIGH END OF ADVISORY RANGE TO 5 INCHES FOR WEST AND CENTRAL COUNTIES AND WENT GENERALLY 2 TO 4 INCHES FOR ERN COUNTIES. TONIGHT...DEEP MOISTURE QUICKLY EXITS FROM WEST TO EAST THIS EVENING AS SHORTWAVE DEPARTS SE OF REGION AND MODEL SOUNDINGS SHOW GOOD MID-LVL SUBSIDENCE/DRYING LATE TONIGHT. WAA DEVELOPING FROM THE WEST LATE TONIGHT AHEAD OF NEXT SHORTWAVE APPROACHING FM THE NRN PLAINS MAY BRIEFLY ALLOW FOR SOME PATCHY FREEZING DRIZZLE TO FORM OVER ERN COUNTIES IN UPSLOPE SOUTHERLY FLOW AS DGZ DRIES OUT...BUT STILL NOT CONFIDENT ENOUGH TO INCLUDE IN FCST. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 522 AM EST MON FEB 17 2014 ZONAL FLOW BRINGS MULTIPLE SHORTWAVES ACROSS THE REGION THROUGH THE UPCOMING WEEK. STRONGEST WAVE BEYOND TODAY IS STILL ON TRACK TO IMPACT GREAT LAKES THURSDAY AND THURSDAY NIGHT THOUGH CURRENT INDICATIONS ARE THAT BIGGEST IMPACT WILL STAY MORE OVER THE OHIO VALLEY AND LOWER GREAT LAKES. OPPORTUNITY TO FINALLY REACH ABOVE FREEZING WFO MARQUETTE WILL BE THE MIDDLE OF THIS WEEK...THOUGH IT IS NOT LOOKING AS SURE AS IT DID THE LAST COUPLE DAYS. WHATEVER WARM UP OCCURS WILL NOT LAST AS IN WAKE OF THE LATE WEEK SYSTEM LARGER SCALE TROUGHING WITH COLDER TEMPERATURES DEVELOPS OVER MUCH OF THE CNTRL CONUS BY NEXT WEEKEND. TUESDAY AND TUESDAY NIGHT...SHORTWAVE AND SFC LOW THAT ARE BRINGING SNOW TO REGION TODAY HEAD OFF ACROSS NEW ENGLAND. WESTERLY FLOW ALOFT WILL BRING ADDITIONAL SHORTWAVES FROM THE NORTHERN PLAINS TO THE WESTERN GREAT LAKES BY TUESDAY AFTN. STRONGEST WAVE ON TUESDAY CROSSES SOUTHERN MANITOBA INTO ONTARIO...WITH ASSOCIATED 995-1000MB SFC LOW MOVING ACROSS ONTARIO IN THE AFTN...TO THE NORTH OF LK SUPERIOR. SOUNDINGS SHOW PLENTY OF MID LEVEL MOISTURE TO H7 BUT ALSO HAVE A LOT OF DRY AIR BLO THAT. ONLY EXCEPTION IS OVER EASTERN CWA WHERE THERE MAY BE ENOUGH LOW-LEVEL MOISTURE TO RESULT IN SOME FREEZING DRIZZLE IN THE MORNING. H85 FRONT LIKELY WILL BE VCNTY OF SOUTHERN LK SUPERIOR SO KEPT SLIGHT CHANCES MAINLY OVER LK SUPERIOR AND IN THE FAR NORTH CWA. WARMEST TEMPS OVER FAR WEST WHERE MAY BE SOME BKN SUNSHINE TO START THE DAY. H925-H9 TEMPS STILL AROUND 0C SO WOULD NOT TAKE MUCH MIXING TO PUNCH TEMPS INTO AT LEAST MID 30S. FARTHER TO THE EAST...MORE CLOUDS AND SW WINDS OFF MAINLY ICE COVERED LK MICHIGAN SHOULD KEEP TEMPS BLO FREEZING. GENERALLY QUIET TUESDAY NIGHT THOUGH WILL HAVE TO WATCH WESTERN CWA LATE AS THERE MAY BE ENOUGH LOW-LEVEL MOISTURE AND UPSLOPE IN WAKE OF SFC TROUGH WORKING THROUGH TO PRODUCE LGT PRECIP. SOUNDINGS WOULD SUPPORT SOME RISK OF FREEZING DRIZZLE WITH LIMITED MOISTURE IN DGZ...THAT IS IF THERE IS SUFFICIENT MOISTURE IN THE LOW-LEVELS. WEDNESDAY...EARLIER IT LOOKED AS THERE WOULD BE NW WINDS IN WAKE OF TROUGH ON TUESDAY TO RESULT IN COOLING FOR THE NORTH OFF ICE COVERED LK SUPERIOR. WINDS IN BLYR NOW MORE WRLY WHICH OPENS POSSIBILITY OF WARMER TEMPERATURES OVER MUCH OF CWA...EXCEPT ALONG IMMEDIATED LK SUPERIOR SHORE OVER WESTERN CWA AND ACROSS KEWEENAW PENINSULA. BIAS CORRECTED GUIDANCE INDICATED MID 30S FOR MOST AREAS WITH EVEN TEMPS AROUND 40 IN THE SCNTRL. USED THIS SOLN AS A BLEND INTO PREVIOUS FORECAST WHICH RESULTED IN SOLID MID 30S FOR GOOD PART OF CWA. COULD BE SOME LOW-LEVEL MOISTURE TO BEGIN THE DAY...BUT THIS SHOULD SCOUR OUT BY AFTN. OVERALL A QUIET WEATHER DAY OUT AHEAD OF STRONGER LOW-MID LEVEL TROUGHING DEVELOPING OVER THE CNTRL CONUS. THURSDAY AND FRIDAY...FATE OF THE LATE WEEK SYSTEM IS STILL CLOUDED WITH MUCH UNCERTAINTY AT THIS POINT. ECMWF AND GFS TRENDED BACK TO MORE WRAPPED UP AND WETTER SYSTEM AS SOUTHERN BRANCH SHORTWAVE DOMINATES AND ALLOWS THE LARGER SCALE SHORTWAVE TROUGH TO BECOME MORE NEGATIVELY TILTED AS IT SWEEPS ACROSS UPPER GREAT LAKES. RESULTING SFC LOW DEEPENS TO SUB 980MB LOW OVER UPPER LAKES BY THURSDAY NIGHT. AS ALLUDED TO YDY...SHORTWAVES THAT HELP FORM THIS SYSTEM ARE STILL AROUND THE ALLUTIANS AND MAYBE EVEN FARTHER WEST THAN THAT OVER NORTHERN RUSSIA. SO...ALTHOUGH THE 00Z ECMWF SOLUTION COULD OCCUR AS IT SHOWED SOMETHING SIMILAR TWO DAYS AGO...IT IS ESSENTIALLY ONE OF MANY SOLNS THAT REPRESENT THE MODEL ENSEMBLE AT THIS POINT. ONLY CHANGE THAT WAS MADE COMPARED TO CONSENSUS WAS TO LINGER CHANCE POPS ON THURSDAY NIGHT IN CASE THE SLOWER/WRAPPED UP IDEA IS CORRECT. ALSO BROUGHT CHANCE FOR RAIN FARTHER NORTH OVER EASTERN CWA. SEEMS THAT IF THE WARMER IDEA IS RIGHT...FZRA COULD ALSO BE AN ISSUE TOO DUE TO LIMITED LOW-LEVEL WARM AIR ADVECTION BLO H85 OR MAYBE JUST FROM THE RAIN FREEZING ON SUB FREEZING ROAD SURFACES DUE TO THE PERSISTENT CHILL THAT HAS BEEN WITH US SINCE EARLY DECEMBER. EVEN THOUGH THE SPECIFICS WITH THIS SYSTEM ARE FAR FROM CERTAIN AND WILL LIKELY CHANGE UNTIL LATER THIS WEEK...THINK IT IS WORTH A HEADS UP MENTION IN THE HAZARDOUS WEATHER OUTLOOK. PRIMARY ISSUE INTO FRIDAY WILL BE STRONGER WINDS CLOSER TO LK SUPERIOR WITH SMALL CHANCES OF SNOW SHOWERS IN LINGERING CYCLONIC MOIST FLOW ON BACKSIDE OF THE DEPARTING LOW PRESSURE SYSTEM. THE WARM UP WILL BE OVER BUT TEMPS WILL BE AROUND NORMAL WITH READINGS IN THE MID TO UPPER 20S. UNCERTAINTY HIGH BEYOND FRIDAY. MODEL CONSENSUS WAS USED FOR NOW WHICH FEATURES PLETHORA OF SLIGHT CHANCE POPS. SEEMS THAT IDEA OF SHORTWAVE LIFTING BACK ACROSS THE AREA AND BRINGING SOME LGT SNOW IS OFF THE TABLE NOW AS THAT SYSTEM IS MUCH WEAKER AND FCST TO REMAIN WELL TO THE SOUTH AND EAST OF CWA IF IT IS THERE AT ALL. TEMPS SATURDAY IN THE TEENS AND LOWER 20S...WITH MORE NOTABLE COOLING FOR SUNDAY WITH HIGHS IN THE LOWER TO MIDDLE TEENS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 708 AM EST MON FEB 17 2014 A LOW PRESSURE SYSTEM APPROACHING FROM THE PLAINS WILL SPREAD SNOW WEST TO EAST ACROSS UPPER MICHIGAN TODAY. SNOW REACHING KIWD HAS ALREADY DROPPED VSBY TO IFR THERE. EXPECT VSBYS AND/OR CIGS TO LOWER TO IFR BY LATE MORNING AT KCMX. KSAW HAS SEEN CIGS LOWER TO LIFR IN UPSLOPE SE FLOW. EXPECT VSBY TO LOWER TO IFR AROUND 18Z WITH ONSET OF HEAVIER SNOW. COULD SEE SOME PERIODS OF LIFR VSBYS/CIGS AT SAW AND CMX DURING THE AFTERNOON HOURS BEFORE ALL SITES IMPROVE TO MVFR THIS EVENING AND TO VFR OVERNIGHT TONIGHT. IN ADDITION TO THE SNOW...A LOW LEVEL JET OVER THE AREA WILL CONTRIBUTE TO LLWS THIS MORNING. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 522 AM EST MON FEB 17 2014 WINDS ARE FORECAST TO BE LESS THAN 30 KTS THIS WEEK. LOW PRESSURE SYSTEM MOVING THROUGH LATE IN THE WEEK MAY RESULT IN STRONGER WINDS THAN CURRENTLY FORECAST...MAINLY ON THURSDAY AFTERNOON AND THURSDAY NIGHT. GALES MAY EVEN OCCUR. ONCE THIS LOW LIFTS TO THE NORTH...WEST WINDS TO 30 KTS OR GALES APPEAR LIKELY ON FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 1 PM THIS AFTERNOON TO 1 AM EST TUESDAY FOR MIZ006-007-014-085. WINTER WEATHER ADVISORY UNTIL 10 PM EST /9 PM CST/ THIS EVENING FOR MIZ001-003>005-010>013-084. WINTER WEATHER ADVISORY UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR MIZ002-009. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...VOSS LONG TERM...JLA AVIATION...VOSS MARINE...JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
524 AM EST MON FEB 17 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 522 AM EST MON FEB 17 2014 09Z WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL PATTERN ACROSS THE WEST AND CENTRAL CONUS WITH A MID/UPPER LEVEL TROUGH AND SEVERAL EMBEDDED SHRTWVS EMERGING FROM THE NRN ROCKIES INTO THE WRN PLAINS. WAA/ISENTROPIC LIFT AHEAD OF THIS SHORTWAVE TROUGH HAS ALLOWED MID-HIGH CLOUDS TO SPREAD INTO THE FCST AREA FM THE WEST. AS A RESULT...MUCH BELOW ZERO TEMPS FM LAST EVENING OVER CENTRAL AND EASTERN COUNTIES OF THE CWA HAVE BEGUN TO MODERATE ABV ZERO AT MANY LOCATIONS. SOME LIGHT SNOW IS ALSO NOW APPEARING ON RADAR AND SFC OBS OVER NCNTRL WI AND FAR WRN UPR MI. TODAY...MODELS IN GENERALLY GOOD AGREEMENT ON DEPICTION/MOVEMENT OF MAIN SHORTWAVE NOW OVER WRN NEBRASKA TRACKING IT AND ASSOC SFC LOW ESE THROUGH CNTRL ILLINOIS AND NRN INDIANA LATE AFTERNOON/EARLY EVENING. NORTHERN SHORTWAVE OVER THE DAKOTAS APPEARS TO BECOME MORE SHEARED OUT WITH TIME AS IT APPROACHES THE WRN LAKES LATE THIS AFTERNOON. THIS IS REFLECTED IN 700-300 MB LAYER Q-VECTORS WHICH SHOWS BEST CONV/LIFT GENERALLY PASSING SOUTH AND EAST OF THE FCST AREA THIS AFTERNOON. ALSO A LIMITING FACTOR FOR HEAVY SNOW TODAY OVER OUR AREA IS THE VERY DRY AIRMASS ALREADY IN PLACE AS NOTED ON 00Z GRB AND APX SOUNDINGS. CONSEQUENTLY..IT WILL TAKE LONGER FOR COLUMN TO MOISTEN FM ISENTROPIC ASCENT AS THUS WILL LIKELY LIMIT SNOW AMOUNTS SOMEWHAT. CONTINUED THE PREV FCST TREND OF GOING ON THE LOWER END OF MODEL GUIDANCE FOR QPF AMOUNTS RANGING FROM .15 INCH FAR EAST TO NEARLY .3 INCH NEAR MNM. USING COBB METHOD AVERAGED SLR VALUES AROUND 17:1...TOTAL SNOW AMOUNTS FROM THIS SYSTEM WILL LIKELY FALL INTO THE 3 TO 5 INCH RANGE ACROSS MUCH OF THE AREA...BUT FAR NE CWA MAY STRUGGLE TO REACH MINIMAL ADVISORY CRITERIA OF 3 INCHES DUE TO EFFECTS OF ATTENDANT DRY AIR DELAYING ARRIVAL OF PCPN UNTIL MAINLY AFTERNOON. SSE WINDS ARE EXPECTED TO INCREASE AND GUST NEAR 25 MPH AT TIMES BY LATE MORNING/AFTERNOON WHICH MAY CONTRIBUTE TO SOME BLSN BUT NOTHING OF GREAT SIGNIFICANCE. CONTINUED THE WINTER WEATHER ADVISORIES ACROSS THE AREA BUT GIVEN POTENTIAL LIMITING FACTORS MENTIONED ABOVE...LOWERED HIGH END OF ADVISORY RANGE TO 5 INCHES FOR WEST AND CENTRAL COUNTIES AND WENT GENERALLY 2 TO 4 INCHES FOR ERN COUNTIES. TONIGHT...DEEP MOISTURE QUICKLY EXITS FROM WEST TO EAST THIS EVENING AS SHORTWAVE DEPARTS SE OF REGION AND MODEL SOUNDINGS SHOW GOOD MID-LVL SUBSIDENCE/DRYING LATE TONIGHT. WAA DEVELOPING FROM THE WEST LATE TONIGHT AHEAD OF NEXT SHORTWAVE APPROACHING FM THE NRN PLAINS MAY BRIEFLY ALLOW FOR SOME PATCHY FREEZING DRIZZLE TO FORM OVER ERN COUNTIES IN UPSLOPE SOUTHERLY FLOW AS DGZ DRIES OUT...BUT STILL NOT CONFIDENT ENOUGH TO INCLUDE IN FCST. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 522 AM EST MON FEB 17 2014 ZONAL FLOW BRINGS MULTIPLE SHORTWAVES ACROSS THE REGION THROUGH THE UPCOMING WEEK. STRONGEST WAVE BEYOND TODAY IS STILL ON TRACK TO IMPACT GREAT LAKES THURSDAY AND THURSDAY NIGHT THOUGH CURRENT INDICATIONS ARE THAT BIGGEST IMPACT WILL STAY MORE OVER THE OHIO VALLEY AND LOWER GREAT LAKES. OPPORTUNITY TO FINALLY REACH ABOVE FREEZING WFO MARQUETTE WILL BE THE MIDDLE OF THIS WEEK...THOUGH IT IS NOT LOOKING AS SURE AS IT DID THE LAST COUPLE DAYS. WHATEVER WARM UP OCCURS WILL NOT LAST AS IN WAKE OF THE LATE WEEK SYSTEM LARGER SCALE TROUGHING WITH COLDER TEMPERATURES DEVELOPS OVER MUCH OF THE CNTRL CONUS BY NEXT WEEKEND. TUESDAY AND TUESDAY NIGHT...SHORTWAVE AND SFC LOW THAT ARE BRINGING SNOW TO REGION TODAY HEAD OFF ACROSS NEW ENGLAND. WESTERLY FLOW ALOFT WILL BRING ADDITIONAL SHORTWAVES FROM THE NORTHERN PLAINS TO THE WESTERN GREAT LAKES BY TUESDAY AFTN. STRONGEST WAVE ON TUESDAY CROSSES SOUTHERN MANITOBA INTO ONTARIO...WITH ASSOCIATED 995-1000MB SFC LOW MOVING ACROSS ONTARIO IN THE AFTN...TO THE NORTH OF LK SUPERIOR. SOUNDINGS SHOW PLENTY OF MID LEVEL MOISTURE TO H7 BUT ALSO HAVE A LOT OF DRY AIR BLO THAT. ONLY EXCEPTION IS OVER EASTERN CWA WHERE THERE MAY BE ENOUGH LOW-LEVEL MOISTURE TO RESULT IN SOME FREEZING DRIZZLE IN THE MORNING. H85 FRONT LIKELY WILL BE VCNTY OF SOUTHERN LK SUPERIOR SO KEPT SLIGHT CHANCES MAINLY OVER LK SUPERIOR AND IN THE FAR NORTH CWA. WARMEST TEMPS OVER FAR WEST WHERE MAY BE SOME BKN SUNSHINE TO START THE DAY. H925-H9 TEMPS STILL AROUND 0C SO WOULD NOT TAKE MUCH MIXING TO PUNCH TEMPS INTO AT LEAST MID 30S. FARTHER TO THE EAST...MORE CLOUDS AND SW WINDS OFF MAINLY ICE COVERED LK MICHIGAN SHOULD KEEP TEMPS BLO FREEZING. GENERALLY QUIET TUESDAY NIGHT THOUGH WILL HAVE TO WATCH WESTERN CWA LATE AS THERE MAY BE ENOUGH LOW-LEVEL MOISTURE AND UPSLOPE IN WAKE OF SFC TROUGH WORKING THROUGH TO PRODUCE LGT PRECIP. SOUNDINGS WOULD SUPPORT SOME RISK OF FREEZING DRIZZLE WITH LIMITED MOISTURE IN DGZ...THAT IS IF THERE IS SUFFICIENT MOISTURE IN THE LOW-LEVELS. WEDNESDAY...EARLIER IT LOOKED AS THERE WOULD BE NW WINDS IN WAKE OF TROUGH ON TUESDAY TO RESULT IN COOLING FOR THE NORTH OFF ICE COVERED LK SUPERIOR. WINDS IN BLYR NOW MORE WRLY WHICH OPENS POSSIBILITY OF WARMER TEMPERATURES OVER MUCH OF CWA...EXCEPT ALONG IMMEDIATED LK SUPERIOR SHORE OVER WESTERN CWA AND ACROSS KEWEENAW PENINSULA. BIAS CORRECTED GUIDANCE INDICATED MID 30S FOR MOST AREAS WITH EVEN TEMPS AROUND 40 IN THE SCNTRL. USED THIS SOLN AS A BLEND INTO PREVIOUS FORECAST WHICH RESULTED IN SOLID MID 30S FOR GOOD PART OF CWA. COULD BE SOME LOW-LEVEL MOISTURE TO BEGIN THE DAY...BUT THIS SHOULD SCOUR OUT BY AFTN. OVERALL A QUIET WEATHER DAY OUT AHEAD OF STRONGER LOW-MID LEVEL TROUGHING DEVELOPING OVER THE CNTRL CONUS. THURSDAY AND FRIDAY...FATE OF THE LATE WEEK SYSTEM IS STILL CLOUDED WITH MUCH UNCERTAINTY AT THIS POINT. ECMWF AND GFS TRENDED BACK TO MORE WRAPPED UP AND WETTER SYSTEM AS SOUTHERN BRANCH SHORTWAVE DOMINATES AND ALLOWS THE LARGER SCALE SHORTWAVE TROUGH TO BECOME MORE NEGATIVELY TILTED AS IT SWEEPS ACROSS UPPER GREAT LAKES. RESULTING SFC LOW DEEPENS TO SUB 980MB LOW OVER UPPER LAKES BY THURSDAY NIGHT. AS ALLUDED TO YDY...SHORTWAVES THAT HELP FORM THIS SYSTEM ARE STILL AROUND THE ALLUTIANS AND MAYBE EVEN FARTHER WEST THAN THAT OVER NORTHERN RUSSIA. SO...ALTHOUGH THE 00Z ECMWF SOLUTION COULD OCCUR AS IT SHOWED SOMETHING SIMILAR TWO DAYS AGO...IT IS ESSENTIALLY ONE OF MANY SOLNS THAT REPRESENT THE MODEL ENSEMBLE AT THIS POINT. ONLY CHANGE THAT WAS MADE COMPARED TO CONSENSUS WAS TO LINGER CHANCE POPS ON THURSDAY NIGHT IN CASE THE SLOWER/WRAPPED UP IDEA IS CORRECT. ALSO BROUGHT CHANCE FOR RAIN FARTHER NORTH OVER EASTERN CWA. SEEMS THAT IF THE WARMER IDEA IS RIGHT...FZRA COULD ALSO BE AN ISSUE TOO DUE TO LIMITED LOW-LEVEL WARM AIR ADVECTION BLO H85 OR MAYBE JUST FROM THE RAIN FREEZING ON SUB FREEZING ROAD SURFACES DUE TO THE PERSISTENT CHILL THAT HAS BEEN WITH US SINCE EARLY DECEMBER. EVEN THOUGH THE SPECIFICS WITH THIS SYSTEM ARE FAR FROM CERTAIN AND WILL LIKELY CHANGE UNTIL LATER THIS WEEK...THINK IT IS WORTH A HEADS UP MENTION IN THE HAZARDOUS WEATHER OUTLOOK. PRIMARY ISSUE INTO FRIDAY WILL BE STRONGER WINDS CLOSER TO LK SUPERIOR WITH SMALL CHANCES OF SNOW SHOWERS IN LINGERING CYCLONIC MOIST FLOW ON BACKSIDE OF THE DEPARTING LOW PRESSURE SYSTEM. THE WARM UP WILL BE OVER BUT TEMPS WILL BE AROUND NORMAL WITH READINGS IN THE MID TO UPPER 20S. UNCERTAINTY HIGH BEYOND FRIDAY. MODEL CONSENSUS WAS USED FOR NOW WHICH FEATURES PLETHORA OF SLIGHT CHANCE POPS. SEEMS THAT IDEA OF SHORTWAVE LIFTING BACK ACROSS THE AREA AND BRINGING SOME LGT SNOW IS OFF THE TABLE NOW AS THAT SYSTEM IS MUCH WEAKER AND FCST TO REMAIN WELL TO THE SOUTH AND EAST OF CWA IF IT IS THERE AT ALL. TEMPS SATURDAY IN THE TEENS AND LOWER 20S...WITH MORE NOTABLE COOLING FOR SUNDAY WITH HIGHS IN THE LOWER TO MIDDLE TEENS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1251 AM EST MON FEB 17 2014 A LOW PRESSURE SYSTEM OVER THE PLAINS WILL MOVE TOWARD THE AREA...SPREADING SNOW INTO UPPER MICHIGAN ON MONDAY. EXPECT VFR CONDITIONS TONIGHT TO RAPIDLY GIVE WAY TO IFR CONDITIONS MONDAY MORNING AT IWD AND CMX...AND PERHAPS WAITING UNTIL LATE MORNING SAW. COULD SEE SOME PERIODS OF LIFR VSBYS/CIGS AND SAW AND CMX DURING THE AFTERNOON HOURS BEFORE ALL SITES IMPROVE TO MVFR MONDAY EVENING. IN ADDITION TO THE SNOW...A LOW LEVEL JET WILL DEVELOP OVER THE AREA LATE TONIGHT INTO MONDAY MORNING. THIS SHOULD ALLOW LLWS TO DEVELOP LATE TONIGHT AND CONTINUE THROUGH THE MORNING HOURS. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 522 AM EST MON FEB 17 2014 WINDS ARE FORECAST TO BE LESS THAN 30 KTS THIS WEEK. LOW PRESSURE SYSTEM MOVING THROUGH LATE IN THE WEEK MAY RESULT IN STRONGER WINDS THAN CURRENTLY FORECAST...MAINLY ON THURSDAY AFTERNOON AND THURSDAY NIGHT. GALES MAY EVEN OCCUR. ONCE THIS LOW LIFTS TO THE NORTH...WEST WINDS TO 30 KTS OR GALES APPEAR LIKELY ON FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 1 PM THIS AFTERNOON TO 1 AM EST TUESDAY FOR MIZ006-007-014-085. WINTER WEATHER ADVISORY UNTIL 10 PM EST /9 PM CST/ THIS EVENING FOR MIZ001-003>005-010>013-084. WINTER WEATHER ADVISORY UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR MIZ002-009. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...VOSS LONG TERM...JLA AVIATION...MRD MARINE...JLA
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
955 AM CST MON FEB 17 2014 .UPDATE... ISSUED AT 926 AM CST MON FEB 17 2014 LATEST MSAS SHOWS ELONGATED SFC PRESS TROUGH EXTENDING FROM SCTRL MANITOBA ACROSS NWRN MN INTO WRN IOWA. SFC PRESS FALLS CONTINUE AHEAD OF THE FEATURE AS A RESULT OF THE WARM AIR ADVECTION. LATEST SPC MESO SHOWS RELATIVELY WEAK 85H FRONTOGENESIS AS CORE OF STRONGEST LLJ HAS TRANSLATED INTO ERN WISC ZONES. BUFKIT TIME/HEIGHT XSECTS OF DGZ/OMEGA PATTERN INDICATES MAJORITY OF OMEGA IS OCCURRING JUST ABOVE MOST FAVORED DGZ. PLAN VIEW OF DGZ/OMEGA FROM NAM12 SUGGESTS SNOWFALL RATES OF 1/2 TO 1 INCH/HR WILL OCCUR OVER MOST OF CWA THROUGH 18Z. AFTER THAT TIME...OMEGA DECREASES CONSIDERABLY AND SATURATION IN ICE NUCLEATION LAYER DECREASES DRAMATICALLY FROM WEST TO EAST. THIS IS SUPPORTED ALSO IN THE LATEST NARRE-TL PROBABILISTIC REFLECTIVITY PRODUCTS. NOTED A FEW METAR REPORTS WITH UP IN PAST 2 HRS JUST WEST OF CWA ON BACK EDGE OF FAVORED ICE NUCLEATION LAYER. MAY SEE SOME PATCHY FZDZ AT BACK EDGE OF PRECIP THIS AFTN BUT WILL LEAVE OUT FOR NOW. CURRENT EXPIRATION OF ADVISORY/WARNING LOOKS GOOD. TOTAL AMOUNTS MAY BE LESS THAN 6" FOR MOST OF TWIN PORTS VICINITY WITH HIGHEST TOTALS ALONG NORTH SHORE AS ALREADY MENTIONED IN VARIOUS PRODUCTS. && .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 304 AM CST MON FEB 17 2014 FORECAST CONCERNS ARE ON HEADLINES. SFC LOW CENTER AT 08Z WAS LOCATED IN CENTRAL SASKATCHEWAN WITH A WARM FRONT SEWD INTO THE EASTERN DAKOTAS. LIGHT SNOW HAS FORMED AHEAD OF THIS SYSTEM IN AN AREA OF 700MB FGEN DRAPED OVER THE FA FROM THE ARROWHEAD INTO NW WI. THIS IS DEPICTED WELL ON RADAR WITH FIRST BAND OF MODERATE SNOW...WITH VSBYS DOWN TO A HALF MILE...LIFTING NEWD INTO THE ARROWHEAD AND NW WI AT 0830Z. AFTER THIS INITIAL BAND...THERE APPEARS TO BE A BREAK IN THE ACTION WITH NO SNOW FOR A FEW HOURS AS THE 700MB FGEN MOVES OUT OF THE AREA. NEXT BAND OF FGEN IS DUE TO ARRIVE IN THE FA BY 12Z AT 850MB. THIS IS ASSOCIATED WITH THE LARGE BATCH OF SNOW IN SE SD AT 0830Z. EXPECT SNOW FALL RATES TO APPROACH ONE INCH PER HOUR UNTIL AROUND 15Z. SNOW AMOUNTS SHOULD RANGE FROM 3 TO 4 INCHES BETWEEN 12Z AND 18Z MAINLY ALONG AND E OF HIGHWAY 53...AND ALONG THE I35 CORRIDOR FROM DULUTH TO PINE CITY. 1 TO 3 INCHES TO THE W OF HIGHWAY 53. THE SNOW WILL PERSIST UNTIL 21Z AND THEN START TO DIMINISH FROM W TO E AS THE WARM FRONT MOVES THROUGH MUCH OF THE AREA AND REACHES THE TIP OF THE ARROWHEAD SEWD TO THE EASTERN EDGE OF THE FA BY 00Z TUESDAY. BEHIND THE FRONT IS DRIER AND WARMER AIR. HAVE LEFT THE HEADLINES AS IS...BUT DID EXTEND THE WARNING OVER THE EASTERN WI FA UNTIL 00Z WITH FROPA AND TO MATCH NEIGHBORING OFFICES. THE SNOW WILL CONTINUE TO DIMINISH FROM 00Z TO 03Z AS THE BEST FORCING HAS MOVED E OF THE FA ALONG WITH THE WARM FRONT. ONLY EXPECTING AN ADDITIONAL TENTH OF AN INCH OF SNOW DURING THIS TIME. AFTER 03Z...HAVE REMOVED POPS UNTIL 08Z WHEN A MID LEVEL SHORT WAVE CLIPS THE INTERNATIONAL BORDER. SOME FGEN IS NOTED AT 925MB...BUT HAVE SMALL/LOW POPS AS MOISTURE WILL BE LACKING AND PCPN IS ONLY SUPPORTED BY THE GFS AND ECMWF. NAM/GEM/SREF/UKMET AND THE SHORT TERM HIRES MODELS ARE DRY. HAVE REMOVED THE MENTION OF -FZDZ WHICH IS NO LONGER SUPPORTED BY ANY OF THE MODELS. A WEAK COLD FRONT IS DUE TO MOVE THROUGH THE FA ON TUESDAY. MOISTURE IS LIMITED...BUT DO HAVE SOME POPS ACROSS THE FAR N DUE TO ITS PROXIMITY TO THE SFC LOW CENTER MOVING THROUGH SOUTH CENTRAL CANADA. AMOUNTS WILL BE LIGHT. EVEN THOUGH SFC MAX TEMPS WILL BE IN THE 30S...THERMAL PROFILES SUGGEST THE PTYPE WILL BE ALL SNOW. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 304 AM CST MON FEB 17 2014 A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE NORTHLAND TUESDAY NIGHT PASSING THROUGH ON WEDNESDAY. MOST AREAS WILL BE DRY AND MILD...WITH HIGHS WEDNESDAY IN THE THIRTIES. ANOTHER SHORTWAVE WILL IMPACT THE REGION LATE WEDNESDAY NIGHT INTO THURSDAY NIGHT...AND BRING A CHANCE FOR SNOW. THE GFS/ECMWF ARE IN DECENT AGREEMENT WEDNESDAY NIGHT HAVING TWO SEPARATE WAVES WITH A SURFACE LOW ALONG OR JUST NORTH OF THE INTERNATIONAL BORDER WITH A SECOND LOW IN THE CENTRAL/SOUTHERN PLAINS REGION. THE ECMWF REALLY DEEPENS THE SOUTHERN LOW AS IT MOVES NORTHEAST INTO SOUTHEAST WI/SOUTHERN LAKE MICHIGAN BY 00Z FRI...AND CONTINUES TO DEEPEN THE LOW ANOTHER 16MB OVER 12 HOURS THURSDAY NIGHT AS IT MOVES TO EASTERN LAKE SUPERIOR. OTHER THAN THE STRENGTH OF THE LOW...THE GFS/ECMWF REMAIN IN DECENT AGREEMENT THROUGH 12Z FRI...WITH THE GFS FURTHER EAST WITH THE LOW AT 12Z FRI. WE BACKED OFF ON POPS A BIT WEDNESDAY NIGHT...AND INCREASED SOME THURSDAY INTO THURSDAY NIGHT...ESPECIALLY OVER EASTERN AREAS. THOSE WITH TRAVEL PLANS THURSDAY-THURSDAY NIGHT SHOULD MONITOR THE FORECAST CLOSELY AS THIS SYSTEM IS QUITE STRONG AND A TRACK FURTHER NORTH AND WEST COULD BRING SIGNIFICANTLY HIGHER SNOWFALL INTO THE NORTHLAND. THIS LOW WILL ALSO USHER IN COLDER AIR INTO THE REGION THURSDAY NIGHT AND BEYOND. THURSDAY WILL REMAIN IN THE THIRTIES...BUT WILL DROP TO THE TEENS TO LOWER TWENTIES BY FRIDAY...THEN TO 5 TO 15 BY SUNDAY. THE WEEKEND LOOKS TO BE RELATIVELY QUIET AT THIS TIME...WITH PERHAPS SOME LIGHT SNOW OR FLURRIES OVER THE SOUTHERN HALF. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 539 AM CST MON FEB 17 2014 RADAR SHOWED SNOW WAS EXPANDING ACROSS THE REGION...AND WIDESPREAD IFR/MVFR CONDITIONS WILL OCCUR THROUGH MUCH OF THE DAY. WE FOLLOWED CLOSE TO THE RAP IN DIMINISHING THE LOWER CEILINGS TODAY AND HELD ONTO RESTRICTED VSBYS LONGER THAN THE MODELS WOULD SUGGEST. HEAVIEST SNOW WILL OCCUR THROUGH NOON...AND LAST LONGER OVER THE ARROWHEAD AND OVER NORTH CENTRAL WISCONSIN. && .PRELIMINARY POINT TEMPS/POPS... DLH 26 17 35 15 / 100 10 10 10 INL 27 17 33 12 / 100 20 30 10 BRD 33 19 37 13 / 100 0 0 0 HYR 27 16 37 13 / 100 10 0 10 ASX 27 16 37 17 / 100 10 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR MNZ012-020- 021. WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MNZ010-018-025- 026-033>036. WINTER STORM WARNING UNTIL 3 PM CST THIS AFTERNOON FOR MNZ037- 038. WINTER WEATHER ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR MNZ011- 019. WI...WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR WIZ002>004- 008-009. WINTER STORM WARNING UNTIL 3 PM CST THIS AFTERNOON FOR WIZ001- 006-007. LS...NONE. && $$ UPDATE...CANNON SHORT TERM...GSF LONG TERM...MELDE AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS DULUTH MN
539 AM CST MON FEB 17 2014 .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 304 AM CST MON FEB 17 2014 FORECAST CONCERNS ARE ON HEADLINES. SFC LOW CENTER AT 08Z WAS LOCATED IN CENTRAL SASKATCHEWAN WITH A WARM FRONT SEWD INTO THE EASTERN DAKOTAS. LIGHT SNOW HAS FORMED AHEAD OF THIS SYSTEM IN AN AREA OF 700MB FGEN DRAPED OVER THE FA FROM THE ARROWHEAD INTO NW WI. THIS IS DEPICTED WELL ON RADAR WITH FIRST BAND OF MODERATE SNOW...WITH VSBYS DOWN TO A HALF MILE...LIFTING NEWD INTO THE ARROWHEAD AND NW WI AT 0830Z. AFTER THIS INITIAL BAND...THERE APPEARS TO BE A BREAK IN THE ACTION WITH NO SNOW FOR A FEW HOURS AS THE 700MB FGEN MOVES OUT OF THE AREA. NEXT BAND OF FGEN IS DUE TO ARRIVE IN THE FA BY 12Z AT 850MB. THIS IS ASSOCIATED WITH THE LARGE BATCH OF SNOW IN SE SD AT 0830Z. EXPECT SNOW FALL RATES TO APPROACH ONE INCH PER HOUR UNTIL AROUND 15Z. SNOW AMOUNTS SHOULD RANGE FROM 3 TO 4 INCHES BETWEEN 12Z AND 18Z MAINLY ALONG AND E OF HIGHWAY 53...AND ALONG THE I35 CORRIDOR FROM DULUTH TO PINE CITY. 1 TO 3 INCHES TO THE W OF HIGHWAY 53. THE SNOW WILL PERSIST UNTIL 21Z AND THEN START TO DIMINISH FROM W TO E AS THE WARM FRONT MOVES THROUGH MUCH OF THE AREA AND REACHES THE TIP OF THE ARROWHEAD SEWD TO THE EASTERN EDGE OF THE FA BY 00Z TUESDAY. BEHIND THE FRONT IS DRIER AND WARMER AIR. HAVE LEFT THE HEADLINES AS IS...BUT DID EXTEND THE WARNING OVER THE EASTERN WI FA UNTIL 00Z WITH FROPA AND TO MATCH NEIGHBORING OFFICES. THE SNOW WILL CONTINUE TO DIMINISH FROM 00Z TO 03Z AS THE BEST FORCING HAS MOVED E OF THE FA ALONG WITH THE WARM FRONT. ONLY EXPECTING AN ADDITIONAL TENTH OF AN INCH OF SNOW DURING THIS TIME. AFTER 03Z...HAVE REMOVED POPS UNTIL 08Z WHEN A MID LEVEL SHORT WAVE CLIPS THE INTERNATIONAL BORDER. SOME FGEN IS NOTED AT 925MB...BUT HAVE SMALL/LOW POPS AS MOISTURE WILL BE LACKING AND PCPN IS ONLY SUPPORTED BY THE GFS AND ECMWF. NAM/GEM/SREF/UKMET AND THE SHORT TERM HIRES MODELS ARE DRY. HAVE REMOVED THE MENTION OF -FZDZ WHICH IS NO LONGER SUPPORTED BY ANY OF THE MODELS. A WEAK COLD FRONT IS DUE TO MOVE THROUGH THE FA ON TUESDAY. MOISTURE IS LIMITED...BUT DO HAVE SOME POPS ACROSS THE FAR N DUE TO ITS PROXIMITY TO THE SFC LOW CENTER MOVING THROUGH SOUTH CENTRAL CANADA. AMOUNTS WILL BE LIGHT. EVEN THOUGH SFC MAX TEMPS WILL BE IN THE 30S...THERMAL PROFILES SUGGEST THE PTYPE WILL BE ALL SNOW. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 304 AM CST MON FEB 17 2014 A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE NORTHLAND TUESDAY NIGHT PASSING THROUGH ON WEDNESDAY. MOST AREAS WILL BE DRY AND MILD...WITH HIGHS WEDNESDAY IN THE THIRTIES. ANOTHER SHORTWAVE WILL IMPACT THE REGION LATE WEDNESDAY NIGHT INTO THURSDAY NIGHT...AND BRING A CHANCE FOR SNOW. THE GFS/ECMWF ARE IN DECENT AGREEMENT WEDNESDAY NIGHT HAVING TWO SEPARATE WAVES WITH A SURFACE LOW ALONG OR JUST NORTH OF THE INTERNATIONAL BORDER WITH A SECOND LOW IN THE CENTRAL/SOUTHERN PLAINS REGION. THE ECMWF REALLY DEEPENS THE SOUTHERN LOW AS IT MOVES NORTHEAST INTO SOUTHEAST WI/SOUTHERN LAKE MICHIGAN BY 00Z FRI...AND CONTINUES TO DEEPEN THE LOW ANOTHER 16MB OVER 12 HOURS THURSDAY NIGHT AS IT MOVES TO EASTERN LAKE SUPERIOR. OTHER THAN THE STRENGTH OF THE LOW...THE GFS/ECMWF REMAIN IN DECENT AGREEMENT THROUGH 12Z FRI...WITH THE GFS FURTHER EAST WITH THE LOW AT 12Z FRI. WE BACKED OFF ON POPS A BIT WEDNESDAY NIGHT...AND INCREASED SOME THURSDAY INTO THURSDAY NIGHT...ESPECIALLY OVER EASTERN AREAS. THOSE WITH TRAVEL PLANS THURSDAY-THURSDAY NIGHT SHOULD MONITOR THE FORECAST CLOSELY AS THIS SYSTEM IS QUITE STRONG AND A TRACK FURTHER NORTH AND WEST COULD BRING SIGNIFICANTLY HIGHER SNOWFALL INTO THE NORTHLAND. THIS LOW WILL ALSO USHER IN COLDER AIR INTO THE REGION THURSDAY NIGHT AND BEYOND. THURSDAY WILL REMAIN IN THE THIRTIES...BUT WILL DROP TO THE TEENS TO LOWER TWENTIES BY FRIDAY...THEN TO 5 TO 15 BY SUNDAY. THE WEEKEND LOOKS TO BE RELATIVELY QUIET AT THIS TIME...WITH PERHAPS SOME LIGHT SNOW OR FLURRIES OVER THE SOUTHERN HALF. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 539 AM CST MON FEB 17 2014 RADAR SHOWED SNOW WAS EXPANDING ACROSS THE REGION...AND WIDESPREAD IFR/MVFR CONDITIONS WILL OCCUR THROUGH MUCH OF THE DAY. WE FOLLOWED CLOSE TO THE RAP IN DIMINISHING THE LOWER CEILINGS TODAY AND HELD ONTO RESTRICTED VSBYS LONGER THAN THE MODELS WOULD SUGGEST. HEAVIEST SNOW WILL OCCUR THROUGH NOON...AND LAST LONGER OVER THE ARROWHEAD AND OVER NORTH CENTRAL WISCONSIN. && .PRELIMINARY POINT TEMPS/POPS... DLH 26 17 35 15 / 100 10 10 10 INL 27 17 33 12 / 100 20 30 10 BRD 33 19 37 13 / 100 0 0 0 HYR 27 16 37 13 / 100 10 0 10 ASX 27 16 37 17 / 100 10 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR MNZ012-020- 021. WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MNZ010-018-025- 026-033>036. WINTER STORM WARNING UNTIL 3 PM CST THIS AFTERNOON FOR MNZ037- 038. WINTER WEATHER ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR MNZ011- 019. WI...WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR WIZ002>004- 008-009. WINTER STORM WARNING UNTIL 3 PM CST THIS AFTERNOON FOR WIZ001- 006-007. LS...NONE. && $$ SHORT TERM...GSF LONG TERM...MELDE AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
644 AM CST Mon Feb 17 2014 .UPDATE... Issued at 644 AM CST MON FEB 17 2014 Precipitation is rapidly clearing out from west to east so the threat for significant snow and ice is decreasing. Additional icing will be confined to the Moberly/Macon/Kirksville areas and should just be a few hundredths of an inch. Band of light precipitation swinging through far northern MO near Maryville and Bethany is a mix of snow, sleet and rain/freezing rain and will produce very minor snow accumulations less than an inch. It`s possible that precipitation could fill in a bit more over far northern MO over the next few hours and produce up to an inch of snow near Milan and Kirksville. Will continue to remove counties from the advisories as needed as temperatures rise above freezing and precipitation tapers off from west to east. && .DISCUSSION... Issued at 346 AM CST MON FEB 17 2014 Freezing rain is blossoming across central and northern MO early this morning in an area of deep isentropic ascent and increasing moisture. The freezing line has been able to lift a tad further north than what was forecast and currently stretches from just north of St. Joseph to near Chillicothe and just north of Boonville. Temperatures are expected to remain above freezing for the remainder of the day for areas south of this line so the freezing rain advisory will be adjusted to remove a few counties near St. Joe. Further north and east, concern is growing that ice totals may be a bit higher than previously forecast for the Kirksville, Milan and Macon areas. Both the RAP and HRRR have been persistent in producing QPF amounts around a half inch for these areas through mid-morning, most of which would fall as freezing rain. If these amounts were to verify, several counties across northern and northeast Missouri would see ice accumulations between a quarter of an inch and a half inch which would push them into ice storm warning criteria. However, both of these models have been initializing with precipitation too far west near Kansas City where radar echoes have been slow to develop. Isentropic ascent is currently maximized near and east of the US 65 corridor which is where most of the precipitation is, with only weak ascent if not downglide starting to push into western MO. This downglide is forecast to increase through the morning so that precipitation may struggle to intensify over western MO, causing the RAP and HRRR precipitation forecasts to be too high. Will therefore stick with ice totals of a quarter inch or less for northeastern portions of the forecast area. However this area will be watched very closely in case precipitation does expand further west and leads to more ice accumulation than what is currently forecast. Colder air will filter in aloft after 8 am and cause precipitation over northern MO to mix with sleet and snow. Snow and sleet accumulations up to an inch are possible mainly north of a Maryville to Kirksville line. Any sleet and snow should be fairly short lived as isentropic downglide will really increase after 15Z and bring precipitation to a rapid end by noon. The main story behind this system will be rising temperatures with westerly downslope flow bringing temperatures into the middle and upper 50s for most areas on Tuesday. The next weather maker will arrive Wednesday night and Thursday when a surface low will track from southern Kansas into central and northeast Missouri. Rain will overspread the area ahead of this system Wednesday night and Thursday morning and there could be a few thunderstorms near and south of the surface low track. Quasi-zonal upper flow behind this system will keep temperatures several degrees above average through Friday. Models continue to advertise a weak system moving into the area over the weekend with the potential for light wintry precipitation. Higher preference was placed on the more consistent GFS solution which would keep any precipitation amounts fairly light. && .AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning) Issued at 525 AM CST MON FEB 17 2014 Back edge of precipitation is currently close to a STJ-MCI-SZL line with mainly dry conditions expected to the west of this line for the rest of the day. Clearing line already near TOP will make it into the KC area within the next hour or two. Further east areas of freezing rain will impact areas around IRK for several more hours with a tenth or two of ice accumulation expected. Sleet and snow may also fall across this area with minor accumulations. Clearing will reach IRK by 18Z. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...FREEZING RAIN ADVISORY until Noon CST today FOR MOZ014-023>025- 032-033-040. WINTER WEATHER ADVISORY until 9 AM CST this morning FOR MOZ003- 004. WINTER WEATHER ADVISORY until Noon CST today FOR MOZ005>008- 015>017. && $$ UPDATE...Hawblitzel DISCUSSION...Hawblitzel AVIATION...Hawblitzel
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
523 AM CST Mon Feb 17 2014 .DISCUSSION... Issued at 346 AM CST MON FEB 17 2014 Freezing rain is blossoming across central and northern MO early this morning in an area of deep isentropic ascent and increasing moisture. The freezing line has been able to lift a tad further north than what was forecast and currently stretches from just north of St. Joseph to near Chillicothe and just north of Boonville. Temperatures are expected to remain above freezing for the remainder of the day for areas south of this line so the freezing rain advisory will be adjusted to remove a few counties near St. Joe. Further north and east, concern is growing that ice totals may be a bit higher than previously forecast for the Kirksville, Milan and Macon areas. Both the RAP and HRRR have been persistent in producing QPF amounts around a half inch for these areas through mid-morning, most of which would fall as freezing rain. If these amounts were to verify, several counties across northern and northeast Missouri would see ice accumulations between a quarter of an inch and a half inch which would push them into ice storm warning criteria. However, both of these models have been initializing with precipitation too far west near Kansas City where radar echoes have been slow to develop. Isentropic ascent is currently maximized near and east of the US 65 corridor which is where most of the precipitation is, with only weak ascent if not downglide starting to push into western MO. This downglide is forecast to increase through the morning so that precipitation may struggle to intensify over western MO, causing the RAP and HRRR precipitation forecasts to be too high. Will therefore stick with ice totals of a quarter inch or less for northeastern portions of the forecast area. However this area will be watched very closely in case precipitation does expand further west and leads to more ice accumulation than what is currently forecast. Colder air will filter in aloft after 8 am and cause precipitation over northern MO to mix with sleet and snow. Snow and sleet accumulations up to an inch are possible mainly north of a Maryville to Kirksville line. Any sleet and snow should be fairly short lived as isentropic downglide will really increase after 15Z and bring precipitation to a rapid end by noon. The main story behind this system will be rising temperatures with westerly downslope flow bringing temperatures into the middle and upper 50s for most areas on Tuesday. The next weather maker will arrive Wednesday night and Thursday when a surface low will track from southern Kansas into central and northeast Missouri. Rain will overspread the area ahead of this system Wednesday night and Thursday morning and there could be a few thunderstorms near and south of the surface low track. Quasi-zonal upper flow behind this system will keep temperatures several degrees above average through Friday. Models continue to advertise a weak system moving into the area over the weekend with the potential for light wintry precipitation. Higher preference was placed on the more consistent GFS solution which would keep any precipitation amounts fairly light. && .AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning) Issued at 525 AM CST MON FEB 17 2014 Back edge of precipitation is currently close to a STJ-MCI-SZL line with mainly dry conditions expected to the west of this line for the rest of the day. Clearing line already near TOP will make it into the KC area within the next hour or two. Further east areas of freezing rain will impact areas around IRK for several more hours with a tenth or two of ice accumulation expected. Sleet and snow may also fall across this area with minor accumulations. Clearing will reach IRK by 18Z. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...FREEZING RAIN ADVISORY until Noon CST today FOR MOZ014-022>025- 032-033-040. WINTER WEATHER ADVISORY until Noon CST today FOR MOZ005>008- 015>017. FREEZING RAIN ADVISORY until 9 AM CST this morning FOR MOZ011>013. WINTER WEATHER ADVISORY until 9 AM CST this morning FOR MOZ001>004. && $$ DISCUSSION...Hawblitzel AVIATION...Hawblitzel
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
417 PM EST MON FEB 17 2014 .SYNOPSIS... A WEAK FRONT TO CROSS THE AREA OVERNIGHT. HIGH PRESSURE WILL BRIEFLY TAKE HOLD TUESDAY. ANOTHER FRONT WILL AFFECT THE REGION FRIDAY. A WARMING TREND IS STILL ON TAP FOR THIS WEEK. && .NEAR TERM /THROUGH TUESDAY/... TONIGHT...HIGH PRESSURE ALONG THE EAST COAST WILL SLIDE OFFSHORE ALLOWING A COLD FRONT TO CROSS THE AREA OVERNIGHT. MOISTURE WITH THE FRONT WILL REMAIN LIMITED AND MOSTLY CONFINED TO THE LOW LEVELS. AS SUCH HAVE REMAINED WITH SLIGHT CHANCE POPS ACROSS THE NORTHERN AND WESTERN MIDLANDS WITH NO POPS ELSEWHERE AS DOWNSLOPING FURTHER DIMINISHES REMAINING MOISTURE. INCREASING CLOUDS SHOULD KEEP OVERNIGHT LOWS IN THE LOW TO MID 40S. TUESDAY...THE FRONT WILL MOVE EAST OF THE MIDLANDS AND CSRA AROUND SUNRISE. HIGH PRESSURE WILL QUICKLY CROSS THE AREA AS THE FRONT BECOMES STATIONARY ALONG THE GULF COAST. WENT WITH MOS CONSENSUS FOR HIGHS TUESDAY IN THE MID 60S TO LOWER 70S. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...UPPER AND SURFACE LOW PRESSURE WILL BE OFF THE NEW ENGLAND COAST BY TUESDAY NIGHT WITH THE ASSOCIATED FRONT ALSO OFFSHORE. ANOTHER AREA OF SURFACE LOW PRESSURE WILL BE CENTERED OVER SOUTH CENTRAL CANADA WITH A COLD FRONT DRAPED ACROSS THE OHIO AND TENNESSEE VALLEYS. MOISTURE AND CLOUDINESS WILL INCREASE ACROSS THE FORECAST AREA AHEAD OF THE FRONT LATE TUESDAY INTO WEDNESDAY. GFS PRECIPITABLE WATER VALUES ARE AROUND 1 INCH WEDNESDAY MORNING. THE FRONT WILL CROSS THE FORECAST AREA WEDNESDAY MORNING BRINGING ONLY A SLIGHT CHANCE OF RAIN. SURFACE HIGH PRESSURE WILL RETURN BY WEDNESDAY AFTERNOON. ABOVE NORMAL TEMPERATURES ON WEDNESDAY IN THE LOWER TO MIDDLE 70S. WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...MODELS ARE IN GOOD AGREEMENT SHOWING A LARGE TROUGH DEVELOPING OVER THE ROCKIES REGION BY EARLY THURSDAY. THE UPPER TROUGH WILL DIG TOWARD THE CENTRAL PLAINS WITH A DOWNSTREAM RIDGE OVER THE EASTERN CONUS. AT THE SURFACE...AN AREA OF LOW PRESSURE CENTERED OVER THE CENTRAL PLAINS EARLY THURSDAY WILL SHIFT NORTHEASTWARD TOWARD THE GREAT LAKES AND DEEPEN WITH A WARM FRONT EXTENDING INTO THE FORECAST AREA. CONTINUED TO INDICATE A SLIGHT CHANCE OF RAIN ALONG THE WARM FRONT ON THURSDAY. TEMPERATURES ON THURSDAY WILL BE ABOVE NORMAL WITH UPPER RIDGING AND SOUTHERLY FLOW INTO THE AREA. EXPECT HIGHS IN THE LOW TO MID 70S. && .LONG TERM /FRIDAY THROUGH MONDAY/... FRIDAY THROUGH FRIDAY NIGHT...SURFACE LOW PRESSURE WILL CONTINUE TO DEEPEN AS IT SHIFTS NORTHEASTWARD INTO CANADA EARLY FRIDAY WITH A COLD FRONT DRAPED ACROSS THE APPALACHIANS. MODELS SHOW AMPLE MOISTURE ACROSS THE AREA FRIDAY MORNING WITH GFS PRECIPITABLE WATER VALUES AROUND 1.4 INCHES AT 12Z. THE COLD FRONT WILL CROSS THE FORECAST AREA DURING THE FRIDAY MORNING/EARLY AFTERNOON TIME FRAME WITH RAIN LIKELY. THE SPC HAS NORTHERN AND CENTRAL GEORGIA AND THE CAROLINAS IN ITS DAY 5 CONVECTIVE OUTLOOK. STRONG FLOW ALOFT MAY RESULT IN A DAMAGING WIND THREAT. THE COLD FRONT SHOULD BE EAST OF THE FORECAST AREA BY FRIDAY EVENING AS THE UPPER TROUGH SHIFTS EASTWARD AND EXPANDS ACROSS THE EASTERN CONUS. SATURDAY THROUGH MONDAY...THE FRONTAL BOUNDARY MAY STALL ALONG THE COAST ON SATURDAY WITH SURFACE HIGH PRESSURE RIDGING INTO THE FORECAST AREA BEHIND IT. MOISTURE WILL INCREASE AGAIN ON SUNDAY WITH MODEL PRECIPITABLE WATER VALUES RETURNING TO OVER AN INCH. THE NEXT COLD FRONT WILL APPROACH FROM THE WEST MONDAY WITH HIGH PRESSURE AND DRY AIR RETURNING TUESDAY. && .AVIATION /21Z MONDAY THROUGH SATURDAY/... HIGH CONFIDENCE FOR VFR THROUGH THE EVENING. HIGH PRESSURE OVER THE AREA WILL MOVE OFFSHORE THIS EVENING ALLOWING A TROUGH OF LOW PRESSURE TO CROSS THE AREA OVERNIGHT. HIGH CLOUDS WILL CROSS THE TAF SITES THIS AFTERNOON. WILL SEE CLOUDS INCREASING AND LOWERING DURING THE EVENING. BOTH THE RUC AND HRRR MODELS INDICATING IFR CONDITION DEVELOPING AROUND 04Z. CONFIDENCE STILL LOW...SO WILL KEEP VFR OVERNIGHT. BY 18/12Z THE FRONT WILL BE EAST OF THE TAF SITES...SO HIGH CONFIDENCE FOR VFR DURING THE DAY TUESDAY. EXTENDED AVIATION OUTLOOK...CEILING RESTRICTIONS POSSIBLE WEDNESDAY MORNING AS COLD FRONT CROSSES THE REGION AND AGAIN ON FRIDAY AS A STRONG COLD FRONT MOVES THROUGH. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
249 PM EST MON FEB 17 2014 .SYNOPSIS... HIGH PRESSURE ALONG THE COAST WILL MOVE OFFSHORE THIS EVENING ALLOWING A WEAK FRONT TO CROSS THE AREA OVERNIGHT. HIGH PRESSURE WILL BRIEFLY TAKE HOLD TUESDAY. ANOTHER FRONT WILL AFFECT THE REGION FRIDAY. A WARMING TREND IS STILL ON TAP FOR THIS WEEK. && .NEAR TERM /THROUGH TUESDAY/... HIGH PRESSURE ALONG THE EAST COAST WILL SLIDE OFFSHORE THIS EVENING ALLOWING A COLD FRONT TO CROSS THE AREA TONIGHT. MOISTURE WITH THE FRONT WILL REMAIN LIMITED AND MOSTLY CONFINED TO THE LOW LEVELS. AS SUCH HAVE REMAINED WITH SLIGHT CHANCE POPS ACROSS THE NORTHERN AND WESTERN MIDLANDS WITH NO POPS ELSEWHERE AS DOWNSLOPING FURTHER DIMINISHES REMAINING MOISTURE. THE FRONT WILL MOVE EAST OF THE MIDLANDS AND CSRA AROUND SUNRISE TUESDAY. HIGH PRESSURE WILL QUICKLY CROSS THE AREA ON TUESDAY AS THE FRONT BECOMES STATIONARY ALONG THE GULF COAST. TEMPERATURES THIS AFTERNOON ARE WELL ON THE WAY TO HIGHS RANGING FROM THE LOWER 50S NORTH TO MID 60S CSRA. INCREASING CLOUDS SHOULD KEEP OVERNIGHT LOWS IN THE LOW TO MID 40S. WENT WITH MOS CONSENSUS FOR HIGHS TUESDAY IN THE MID 60S TO LOWER 70S. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...UPPER AND SURFACE LOW PRESSURE WILL BE OFF THE NEW ENGLAND COAST BY TUESDAY NIGHT WITH THE ASSOCIATED FRONT ALSO OFFSHORE. ANOTHER AREA OF SURFACE LOW PRESSURE WILL BE CENTERED OVER SOUTH CENTRAL CANADA WITH A COLD FRONT DRAPED ACROSS THE OHIO AND TENNESSEE VALLEYS. MOISTURE AND CLOUDINESS WILL INCREASE ACROSS THE FORECAST AREA AHEAD OF THE FRONT LATE TUESDAY INTO WEDNESDAY. GFS PRECIPITABLE WATER VALUES ARE AROUND 1 INCH WEDNESDAY MORNING. THE FRONT WILL CROSS THE FORECAST AREA WEDNESDAY MORNING BRINGING ONLY A SLIGHT CHANCE OF RAIN. SURFACE HIGH PRESSURE WILL RETURN BY WEDNESDAY AFTERNOON. ABOVE NORMAL TEMPERATURES ON WEDNESDAY IN THE LOWER TO MIDDLE 70S. WEDNESAY NIGHT THROUGH THURSDAY NIGHT...MODELS ARE IN GOOD AGREEMENT SHOWING A LARGE TROUGH DEVELOPING OVER THE ROCKIES REGION BY EARLY THURSDAY. THE UPPER TROUGH WILL DIG TOWARD THE CENTRAL PLAINS WITH A DOWNSTREAM RIDGE OVER THE EASTERN CONUS. AT THE SURFACE...AN AREA OF LOW PRESSURE CENTERED OVER THE CENTRAL PLAINS EARLY THURSDAY WILL SHIFT NORTHEASTWARD TOWARD THE GREAT LAKES AND DEEPEN WITH A WARM FRONT EXTENDING INTO THE FORECAST AREA. CONTINUED TO INDICATE A SLIGHT CHANCE OF RAIN ALONG THE WARM FRONT ON THURSDAY. TEMPERATURES ON THURSDAY WILL BE ABOVE NORMAL WITH UPPER RIDGING AND SOUTHERLY FLOW INTO THE AREA. EXPECT HIGHS IN THE LOW TO MID 70S. && .LONG TERM /FRIDAY THROUGH MONDAY/... FRIDAY THROUGH FRIDAY NIGHT...SURFACE LOW PRESSURE WILL CONTINUE TO DEEPEN AS IT SHIFTS NORTHEASTWARD INTO CANADA EARLY FRIDAY WITH A COLD FRONT DRAPED ACROSS THE APPALACHIANS. MODELS SHOW AMPLE MOISTURE ACROSS THE AREA FRIDAY MORNING WITH GFS PRECIPITABLE WATER VALUES AROUND 1.4 INCHES AT 12Z. THE COLD FRONT WILL CROSS THE FORECAST AREA DURING THE FRIDAY MORNING/EARLY AFTERNOON TIME FRAME WITH RAIN LIKELY. THE SPC HAS NORTHERN AND CENTRAL GEORGIA AND THE CAROLINAS IN ITS DAY 5 CONVECTIVE OUTLOOK. STRONG FLOW ALOFT MAY RESULT IN A DAMAGING WIND THREAT. THE COLD FRONT SHOULD BE EAST OF THE FORECAST AREA BY FRIDAY EVENING AS THE UPPER TROUGH SHIFTS EASTWARD AND EXPANDS ACROSS THE EASTERN CONUS. SATURDAY THROUGH MONDAY...THE FRONTAL BOUNDARY MAY STALL ALONG THE COAST ON SATURDAY WITH SURFACE HIGH PRESSURE RIDGING INTO THE FORECAST AREA BEHIND IT. MOISTURE WILL INCREASE AGAIN ON SUNDAY WITH MODEL PRECIPITABLE WATER VALUES RETURNING TO OVER AN INCH. THE NEXT COLD FRONT WILL APPROACH FROM THE WEST MONDAY WITH HIGH PRESSURE AND DRY AIR RETURNING TUESDAY. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... HIGH CONFIDENCE FOR VFR THROUGH THE EVENING. HIGH PRESSURE OVER THE AREA WILL MOVE OFFSHORE THIS EVENING ALLOWING A TROUGH OF LOW PRESSURE TO CROSS THE AREA OVERNIGHT. HIGH CLOUDS WILL CROSS THE TAF SITES THIS AFTERNOON. WILL SEE CLOUDS INCREASING AND LOWERING DURING THE EVENING. BOTH THE RUC AND HRRR MODELS INDICATING IFR CONDITION DEVELOPING AROUND 04Z. CONFIDENCE STILL LOW...SO WILL KEEP VFR OVERNIGHT. BY 18/12Z THE FRONT WILL BE EAST OF THE TAF SITES...SO HIGH CONFIDENCE FOR VFR DURING THE DAY TUESDAY. EXTENDED AVIATION OUTLOOK...CEILING RESTRICTIONS POSSIBLE WEDNESDAY MORNING AS COLD FRONT CROSSES THE REGION AND AGAIN ON FRIDAY AS A STRONG COLD FRONT MOVES THROUGH. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
135 PM EST MON FEB 17 2014 .SYNOPSIS... HIGH PRESSURE ALONG THE COAST WILL MOVE OFFSHORE THIS EVENING ALLOWING A WEAK FRONT WILL CROSS THE AREA OVERNIGHT. HIGH PRESSURE WILL BRIEFLY TAKE HOLD TUESDAY. ANOTHER FRONT WILL AFFECT THE REGION FRIDAY. A WARMING TREND IS STILL ON TAP FOR THIS WEEK. && .NEAR TERM /THROUGH TUESDAY/... HIGH PRESSURE ALONG THE EAST COAST WILL SLIDE OFFSHORE THIS EVENING ALLOWING A COLD FRONT TO CROSS THE AREA TONIGHT. MOISTURE WITH THE FRONT WILL REMAIN LIMITED AND MOSTLY CONFINED TO THE LOW LEVELS. AS SUCH HAVE REMAINED WITH SLIGHT CHANCE POPS ACROSS THE NORTHERN AND WESTERN MIDLANDS WITH NO POPS ELSEWHERE AS DOWNSLOPING FURTHER DIMINISHES REMAINING MOISTURE. THE FRONT WILL MOVE EAST OF THE MIDLANDS AND CSRA AROUND SUNRISE TUESDAY. HIGH PRESSURE WILL QUICKLY CROSS THE AREA ON TUESDAY AS THE FRONT BECOMES STATIONARY ALONG THE GULF COAST. TEMPERATURES THIS AFTERNOON ARE WELL ON THE WAY TO HIGHS RANGING FROM THE LOWER 50S NORTH TO MID 60S CSRA. INCREASING CLOUDS SHOULD KEEP OVERNIGHT LOWS IN THE LOW TO MID 40S. WENT WITH MOS CONSENSUS FOR HIGHS TUESDAY IN THE MID 60S TO LOWER 70S. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... THE NEXT LOW PRESSURE SYSTEM WILL SWING THROUGH THE GREAT LAKES REGION TUESDAY NIGHT...PUSHING ANOTHER COLD FRONT EASTWARD AND BRING THE STATIONARY FRONT FROM THE COAST BACK NORTHWARD. THIS WILL BRING A WEAK DISTURBANCE THROUGH THE FORECAST AREA LATE TUESDAY NIGHT INTO WEDNESDAY MORNING. MOISTURE WITH THE FRONT WILL AGAIN BE LIMITED WITH MODEL SOUNDINGS INDICATING DRY AIR IN THE MID LEVELS. HAVE ADJUSTED THE POPS SLIGHTLY REMAINING WITH CHANCE OVER MOST OF THE FORECAST AREA...HOWEVER QPF AMOUNTS WILL GENERALLY BE A COUPLE OF HUNDREDTHS. HIGH PRESSURE BUILDING BACK IN DURING THE AFTERNOON HOURS AND AGAIN PUSH THE STATIONARY FRONT JUST SOUTH OF THE AREA FOR WEDNESDAY NIGHT. TEMPERATURES WILL CONTINUE TO WARM WITH AFTERNOON HIGHS IN THE LOWER 70S ON WEDNESDAY...AND OVERNIGHT LOWS IN THE UPPER 40S TO LOWER 50S EACH NIGHT. && .LONG TERM /THURSDAY THROUGH SUNDAY/... UPPER LEVEL PATTERN WILL REMAIN LOW ZONAL THROUGH THE PERIOD ALLOWING FOR PROGRESSION OF SYSTEMS THROUGH THE FORECAST AREA. LOW PRESSURE WILL BE DEEPENING AS IT CROSSES THE CENTRAL MS VALLEY ON THURSDAY AND MOVES INTO THE CENTRAL GREAT LAKES THURSDAY NIGHT. THE ASSOCIATED COLD FRONT WILL CROSS THE GULF STATES THURSDAY NIGHT AND INTO THE FORECAST AREA FRIDAY. THIS WILL BRING INCREASING CHANCES OF RAIN SHOWERS TO THE AREA FOR MUCH OF FRIDAY. HAVE ONLY INCREASED POPS SLIGHTLY FOR THIS TIME PERIOD AS MODELS AGREE ON SYNOPTIC SITUATION BUT DISAGREE ON TIMING WITH GFS CURRENTLY SLOWER THAN ECMWF. THE FRONT WILL STALL ALONG THE COAST FRIDAY EVENING WITH HIGH PRESSURE AND DRIER AIR BUILDING INTO THE REGION. CONFIDENCE LOW FOR SATURDAY AND SUNDAY AS GFS RAPIDLY RETURNS MOISTURE TO THE AREA ON SATURDAY WHILE ECMWF HANGS ON TO DRY AIR INTO SUNDAY. AS A RESULT ON MINOR ADJUSTMENTS MADE TO SATURDAY AND SUNDAY. TEMPERATURES THROUGH THE LONG TERM WILL ABOVE NORMAL. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... HIGH CONFIDENCE FOR VFR THROUGH THE EVENING. HIGH PRESSURE OVER THE AREA WILL MOVE OFFSHORE THIS EVENING ALLOWING A TROUGH OF LOW PRESSURE TO CROSS THE AREA OVERNIGHT. HIGH CLOUDS WILL CROSS THE TAF SITES THIS AFTERNOON. WILL SEE CLOUDS INCREASING AND LOWERING DURING THE EVENING. BOTH THE RUC AND HRRR MODELS INDICATING IFR CONDITION DEVELOPING AROUND 04Z. CONFIDENCE STILL LOW...SO WILL KEEP VFR OVERNIGHT. BY 18/12Z THE FRONT WILL BE EAST OF THE TAF SITES...SO HIGH CONFIDENCE FOR VFR DURING THE DAY TUESDAY. EXTENDED AVIATION OUTLOOK...CEILING RESTRICTIONS POSSIBLE WEDNESDAY MORNING AS COLD FRONT CROSSES THE REGION AND AGAIN ON FRIDAY AS A STRONG COLD FRONT MOVES THROUGH. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
427 PM CST MON FEB 17 2014 .DISCUSSION... 248 PM CST SHORT TERM...THROUGH TONIGHT... WILL LEAVE THE WINTER STORM WARNING AS IS...WITH THE WESTERN COUNTIES ENDING AT 6PM AND THE EASTERN COUNTIES ENDING AT 9PM CST. TWO LOWS ARE OVER THE REGION. THE DEEPER ONE IS OVER SOUTHWEST MN WHILE THE OTHER IS OVER SOUTHERN IL. BOTH LOWS HAVE DEEPENED IN THE PAST HOUR. ALOFT...THERE IS AN UPPER LEVEL TROUGH FROM MN THROUGH MO WITH A SLIGHT NEGATIVE TILT. THIS TROUGH IS PROVIDING THE LIFT FOR THE SNOW. THE RAP HAS HAD A PRETTY GOOD IDEA OF THE FGEN FORCING AND CAPE TODAY. THE FGEN IS FOCUSED JUST SOUTH OF THE CWA AND HAVE IT PASSING FROM MCLEAN COUNTY INTO CENTRAL INDIANA LATE THIS AFTERNOON AND THE CAPE REMAINS ON THE WARM SIDE OF THE FGEN BAND. AS SUCH THINKING THUNDERSNOW WILL REMAIN CONFINED TO AREAS SOUTH OF I-80 AND NORTHWEST INDIANA FOR THE NEXT COUPLE OF HOURS BEFORE SHIFTING INTO INDIANA BY 3PM. BUT THINKING THUNDERSNOW IS NOT AS LIKELY AS IT WAS EARLIER TODAY...AND WE ARE ON A DOWNWARD TREND. AREAS SOUTH OF I-80 AND NW INDIANA...HAVE ALSO BEEN HARDEST HIT BY SNOW THUS FAR WITH REPORTS AS HIGH AS 2.5 INCHES PER HOUR. THE AREA OF SNOW RESPONSIBLE FOR THOSE INTENSE RATES HAS MOVED EAST. HOWEVER ANOTHER BAND OF SNOW COINCIDING WITH THE FGEN BAND STRETCHES FROM MCHENRY COUNTY THROUGH CHAMPAIGN COUNTY. IT JUST MOVED OVER THE OFFICE HERE AND VSBY DROPPED TO LESS THAN 1/8 OF A MILE WITH HEAVY SNOW. AS SUCH WILL KEEP HEAVY SNOW IN THE FORECAST AS THIS BAND PROGRESSES EASTWARD. HAVE THE BAND PUSHING EAST OF THE CWA BY 5PM CST. THE BACK END OF THE SNOW STRETCHES FROM EASTERN MN TO PEORIA TO DECATUR IL AND IS QUICKLY PUSHING EAST AS WELL. AS SUCH QUICKENED THE END TIME OF SNOW IN THE GRIDS. LEFT TOTALS AS IS WITH GENERALLY 4 TO 8 INCHES ACROSS THE CWA. EXPECTING SLIGHTLY LOWER TOTALS ALONG THE IL/WI STATE LINE AND THEN HIGHER TOTALS ACROSS THE SOUTHERN CWA. WITH THIS BEING A WETTER TYPE SNOW...LEFT BLOWING SNOW OUT OF THE FORECAST. WIND GUSTS PICK UP SOUTH OF I-80 BEHIND THE TROUGH AXIS THIS EVENING. GUSTS UP TO 25 KT ARE EXPECTED...AND THEY DIMINISH BY MORNING. FOR TEMPS...THE PREVIOUS FORECAST WAS RIGHT ON SO DID NOT MAKE TOO MANY CHANGES TO TODAYS TEMPS. FOR TONIGHT...WENT A BIT LOWER THAN GUIDANCE GIVEN THE FRESH SNOW AND CLEARING SKIES. LOWS WILL BE IN THE MID TEENS TO AROUND 20. JEE TUESDAY THROUGH WEDNESDAY... SEMI-ZONAL FLOW OVERHEAD CONTINUES TO PUSH THE 500MB TROUGH AXIS TO THE EAST OF THE REGION TUESDAY...WITH SFC RIDGING BUILDING INTO NORTHERN IL/NORTHWEST IN. THE COMBINATION OF RIDGING...P-CLOUDY SKIES...ALONG WITH MID-LVL TEMPS BEGINNING TO WARM...SHOULD ALLOW SFC TEMPS TO WARM MID/UPR 30S TUE AFTN. A FEW POINTS ALONG THE FAR SOUTHERN CWFA COULD TOUCH 40 DEGREES. THEN WITH THE SEMI-ZONAL FLOW ALLOWING FOR A RELATIVELY FLUID ENVIRONMENT...A WEAK TROUGH PIVOTS EAST FROM THE NORTHERN PLAINS TUE AFTN/EVE...AND BRINGS THICKENING CLOUD COVER BACK TO THE FORECAST AREA. LOCAL MODEL WAS INDICATING SOME SPRINKLES WITH THE WEAK WAVE OVER THE NORTHERN PORTIONS OF THE FORECAST AREA TUE EVE...HOWEVER FEEL TOO MUCH DRY AIR WILL NEED TO BE OVERCOME...SO WILL CONTINUE TO RIDE WITH A DRY FORECAST THROUGH TUE NGT INTO WED AS FRONTAL BOUNDARY SWEEPS EAST ACROSS THE CWFA. SFC RIDGING WILL DEPART EAST...HOWEVER BROAD RIDGING ACROSS THE CENTRAL PLAINS WILL THEN PROVIDE ANOTHER DRY INFLUENCE FOR THE AREA INTO WED. THIS FEATURE WILL THEN SHIFT EAST TOWARDS THE OHIO VALLEY. TEMPS ONLY COOL MARGINALLY TUE NGT ALOFT...SO NOT EXPECTING MUCH COOLING AT THE SFC...THUS HAVE HELD ONTO TEMPS IN THE LOW/MID 20S FOR OVERNIGHT LOWS. THEN FOR WED WITH ANOTHER DRY DAY AND P-CLOUDY SKIES...TEMPS SHUD BE ABLE TO WARM BACK ABOVE FREEZING INTO THE LOW/MID 30S. WEAK MID-LVL RIDGE SLIDES OVERHEAD WED AFTN/EVE...WITH SFC RIDGING KEEPING A SLIGHT INFLUENCE OVER THE CWFA THRU EARLY EVE. THIS SHUD KEEP PRECIP OUT OF THE FORECAST AREA UNTIL LATE WED NGT/EARLY THUR. CONFIDENCE...MEDIUM/HIGH. THURSDAY THROUGH FRIDAY... FOCUS REMAINS ON THE THURSDAY TIMEFRAME...ESPECIALLY WITH THE SUBSTANTIAL WARM-UP THAT CONTINUES TO BE PROGGED BY NUMEROUS FORECAST MODELS. WHILE SOME CORRECTIONS CONTINUE TO TAKE PLACE...WITH RESPECT TO THE PLACEMENT/INTENSITY OF THE DEVELOPING SHORTWAVE AND WARM AIR. 500MB TROUGH REMAINS MORE OF AN ELONGATED SETUP...WITH THE VORT MAX OVER THE NORTHERN ROCKIES DESPITE THE TROUGH STRETCHING SOUTH THROUGH THE FOOTHILLS OF COLORADO EARLY THUR. GUIDANCE CONTINUES TO POINT TOWARDS A SFC WAVE DEVELOPING ON THE LEE-SIDE OF THE ROCKIES NEAR SOUTHEAST COLORADO EARLY THUR. WITH THE DOWNSTREAM RIDGING OVER THE SOUTHEAST CONUS...RETURN FLOW MOISTURE WILL LIKELY STREAM NORTH AHEAD OF THIS DEVELOPING SYSTEM. ENSEMBLES HAVE MAINTAINED A DECENT AGREEMENT WITH PWAT VALUES NEARING 1" FOR AREAS ALONG AND SOUTH OF I-80 IN NORTHERN IL/NORTHWEST IN THUR...WITH STRONG MFLUX CONVERGENCE AT 850MB. THIS COUPLED WITH A VERY ROBUST LLVL JET...AND STRONG INSTABILITY...POINT TOWARDS NOT ONLY THE POTENTIAL FOR MODERATE RAIN GIVEN THE SURGE IN WARM AIR OVER THE FORECAST AREA...BUT ALSO THE POSSIBILITY FOR STRONG THUNDERSTORMS. THE SPC HAS A PORTION OF THE FORECAST AREA...OUTLOOKED FOR POSSIBLE STRONG THUNDERSTORMS. THIS REMAINS MAINLY ALONG AND EAST OF A PONTIAC TO RENSSELAER LINE FOR THE MAIN FOCUS AREA...HOWEVER GIVEN THE CONTINUED UNCERTAINTY ON TIMING/INTENSITY/PLACEMENT OF THE SYSTEM THIS WILL LIKELY BE ADJUSTED OVER TIME. SHORTWAVE THEN SLIDES OVER THE FORECAST AREA THUR EVE...WITH A FRONTAL BOUNDARY BRINGING AN END TO THE MILD AIRMASS AND RETURNING P-TYPE BACK TO LGT SNOW BEFORE ENDING FRI MORNING FROM WEST TO EAST. AFTER TEMPS REACHING INTO THE MID/UPR 40S THUR...FRI HIGHS WILL RETURN TO MORE SEASONAL CONDS IN THE LOW/MID 30S. CONFIDENCE...MEDIUM. SATURDAY THROUGH EARLY NEXT WEEK... THE UPCOMING WEEKEND THROUGH EARLY NEXT WEEK PATTERN IS PROGGED TO RETURN TO WHAT HAS BEEN A COMMON PATTERN OF TROUGHING OVER THE GREAT LAKES REGION...WITH HIGH AMPLITUDE RIDGING PUSHING INTO WESTERN CANADA. TEMPS FOR THE WEEKEND WILL COOL BACK INTO THE 20S FOR HIGHS. THEN GUIDANCE IS INDICATING A COUPLE WEAK MID-LVL WAVES TRAVERSING THE REGION FOR THE SECOND HALF OF THE WEEKEND INTO EARLY NEXT WEEK. CONFIDENCE...MEDIUM/HIGH. && .HYDROLOGY... LATEST MODEL GUIDANCE CONTINUES TO INDICATE ENHANCED CONCERN REGARDING FLOODING POTENTIAL FOR THURSDAY...POSSIBLY LINGERING INTO THE WEEKEND. MORE DETAIL METEOROLOGICAL DISCUSSION IS ABOVE. NO CHANGES REALLY TO THE PREVIOUS HYDROLOGICAL DISCUSSION OTHER THAN SLIGHTLY MORE SNOW AND SNOW WATER EQUIVALENT IS EXPECTED TO BE IN PLACE AFTER TODAY`S SNOW SYSTEM. WILL FRESHEN UP THE ESF AGAIN THIS MORNING BUT NOT PLANNING ANY BIG CHANGES. && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 22Z... * MAINLY 1-2SM VSBY TIL 00Z IN LIGHT SNOW...REDUCTION TO 1/2 OR 3/4SM LIKELY DURING 23Z HOUR. VSBY IMPROVEMENT AFTER 00Z...WITH SNOW ENDING 01Z. * LIGHT SOUTHEAST WINDS TURN TO WEST AROUND 00 OR 01Z WITH SPEEDS INCREASING TO 10-15 KT. * VARIABLE MVFR CIGS LOWERING TO LOW END MVFR AS SNOW ENDS...LINGERING INTO MID OR LATE EVENING. MDB //DISCUSSION...UPDATED 22Z... SNOW BEGINNING TO EXIT THE AREA WITH INTENSITY ALSO DIMINISHING BUT ONE LAST BAND IS HEADING EAST TO THE CHICAGO AREA LIKELY REACHING THESE TERMINALS AROUND 23Z. THIS WILL LIKELY BRING VSBY BACK DOWN BELOW 1SM FOR A BRIEF PERIOD. OTHERWISE EXPECT 1-2SM VSBY PRIOR TO THAT. THIS BETTER FOCUSED SNOW WILL EXIT AROUND 00Z THOUGH SOME WRAP AROUND NOTED NEAR DBQ MAY KEEP SOME LIGHT SNOW LINGERING WITH SOME REDUCED VSBY FOR AN HOUR OR TWO BEYOND. BEYOND THAT LOWER MVFR CIGS WILL PERSIST THROUGH THE EVENING. LIGHT AND VARIABLE WINDS WILL TURN WESTERLY AND INCREASE EARLY THIS EVENING. MDB FROM 18Z... GOING FORECAST SEEMS LARGELY ON TRACK FOR THE TERMINALS WITH MODERATE TO HEAVY SNOW SPREADING NORTHEAST INTO THE REGION EARLY THIS AFTERNOON AND UPSTREAM OBS SHOWING VSBY QUICKLY DROPPING TO 1/4 TO 1/2 MILE. NARROW CORRIDOR ON INSTABILITY AHEAD OF AN APPROACHING F-GEN BAND CURRENTLY MOVING ACROSS THE RIVER STILL APPEARS TO BE THE BEST CHANCE FOR THUNDER TO MOVE NEAR THE TERMINALS...THOUGH STILL FAVORS AREAS JUST SOUTH OF DOWNTOWN CHICAGO. MDW MAY BE CLOSE BUT DO NOT HAVE THE CONFIDENCE IN COVERAGE TO ADD AT THIS TIME. DRIER AIR PUSHES INTO THE AREA BY LATE AFTERNOON/EARLY EVENING AND RATES SHOULD TAPER...THEN FORCING ENDS ABRUPTLY MID EVENING. LINGERING LOW LEVEL MOISTURE WILL RESULT IN LOWER MVFR OR PSBLY IFR CIGS HANGING OUT OVERNIGHT...THOUGH EXPECT VFR CONDITIONS BY AROUND DAYBREAK TOMORROW. BMD //ORD AND MDW CONFIDENCE...UPDATED 22Z... * HIGH CONFIDENCE IN PRIMARILY 1-2SM VSBY WITH REDUCTION TO LESS THAN 1SM AT TIMES DURING 23Z HOUR. MEDIUM-HIGH CONFIDENCE IN MVFR TAKING OVER AND SNOW MAINLY ENDING TOWARD 01Z. * MEDIUM-HIGH CONFIDENCE IN WIND TRENDS AND TIMING OF SHIFT TO WEST. * HIGH CONFIDENCE IN VARIABLE MVFR CIGS BECOMING STEADY LOW MVFR EARLY THIS EVENING...MEDIUM CONFIDENCE IN TIMING OF SCATTERING. MDB //OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z... TUESDAY NIGHT THROUGH WEDNESDAY...PREDOMINANTLY VFR. WEDNESDAY NIGHT...RAIN OR FZRA DEVELOPING. THURSDAY..RAIN/FOG/IFR LIKELY. FZRA POSSIBLE IN THE MORNING. FRIDAY...VFR PROBABLE. SATURDAY AND SUNDAY...SOME POTENTIAL FOR SNOW. IZZI && .MARINE... 300 PM CST HAVE EXTENDED THE GALE WARNING FOR THE CENTRAL PORTIONS OF LAKE MICHIGAN INTO THIS EVENING AS A STRONG SOUTHEASTERLY PRESSURE GRADIENT WILL REMAIN...BETWEEN STRONG HIGH PRESSURE SLOWLY MOVES THROUGH THE NERN CONUS AND A DEEP TROUGH AND STRONG COLD FRONT MOVE THROUGH THE UPPER MISSISSIPPI VALLEY AND INTO THE WESTERN GREAT LAKES REGION. THE COLD FRONT WILL PUSH ACROSS THE LAKE TONIGHT AND A WEAK RIDGE WILL QUICKLY FOLLOW THE FRONT...SETTING UP A PERIOD OF RELATIVELY VARIABLE...BUT WEAKER WINDS OVER THE LAKE. BY TUESDAY NIGHT...A CLIPPER TYPE SYSTEM WILL TRACK THROUGH SRN CANADA...DRAGGING ANOTHER COLD FRONT ACROSS THE PLAINS. AS THE FRONTAL TROUGH APPROACHES THE LAKES...SLY-SWLY WINDS WILL INCREASE TO ARND 30KT...WITH OCCASIONAL GALE FORCE GUSTS POSSIBLE. THE NEXT SIGNIFICANT WEATHER SYSTEM TO IMPACT THE LAKES IS EXPECTED TO DEVELOP OVER THE PLAINS WEDNESDAY NIGHT WITH WEAKER LOW PRESSURE DEVELOPING OVER THE DAKOTAS AND A STRONGER LOW DEVELOPING OVER THE SOUTH HIGH PLAINS. THE SOUTHERN LOW WILL BE THE MAIN SYSTEM OF CONCERN AS IT IS EXPECTED TO DEEPEN RAPIDLY AS IT TRACKS THROUGH ERN WISCONSIN THURSDAY NIGHT...WHILE DRAGGING A STRONG COLD FRONT ACROSS THE LAKE. SWLY WINDS MAY APPROACH GALE FORCE JUST AHEAD OF THE COLD FRONT...AND WILL LIKELY EXCEED GALE FORCE WHILE SHIFTING TO WLY FOLLOWING THE FROPA. KREIN && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011- ILZ012-ILZ019-ILZ020-ILZ021-ILZ032-ILZ039 UNTIL 6 PM MONDAY. WINTER STORM WARNING...ILZ006-ILZ013-ILZ014-ILZ022-ILZ023-ILZ033 UNTIL 9 PM MONDAY. IN...WINTER STORM WARNING...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9 PM MONDAY. LM...GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ868-LMZ870-LMZ872-LMZ874-LMZ876 UNTIL 9 PM MONDAY. && $$ 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
NWS CHICAGO/ROMEOVILLE IL
403 PM CST MON FEB 17 2014 .DISCUSSION... 248 PM CST SHORT TERM...THROUGH TONIGHT... WILL LEAVE THE WINTER STORM WARNING AS IS...WITH THE WESTERN COUNTIES ENDING AT 6PM AND THE EASTERN COUNTIES ENDING AT 9PM CST. TWO LOWS ARE OVER THE REGION. THE DEEPER ONE IS OVER SOUTHWEST MN WHILE THE OTHER IS OVER SOUTHERN IL. BOTH LOWS HAVE DEEPENED IN THE PAST HOUR. ALOFT...THERE IS AN UPPER LEVEL TROUGH FROM MN THROUGH MO WITH A SLIGHT NEGATIVE TILT. THIS TROUGH IS PROVIDING THE LIFT FOR THE SNOW. THE RAP HAS HAD A PRETTY GOOD IDEA OF THE FGEN FORCING AND CAPE TODAY. THE FGEN IS FOCUSED JUST SOUTH OF THE CWA AND HAVE IT PASSING FROM MCLEAN COUNTY INTO CENTRAL INDIANA LATE THIS AFTERNOON AND THE CAPE REMAINS ON THE WARM SIDE OF THE FGEN BAND. AS SUCH THINKING THUNDERSNOW WILL REMAIN CONFINED TO AREAS SOUTH OF I-80 AND NORTHWEST INDIANA FOR THE NEXT COUPLE OF HOURS BEFORE SHIFTING INTO INDIANA BY 3PM. BUT THINKING THUNDERSNOW IS NOT AS LIKELY AS IT WAS EARLIER TODAY...AND WE ARE ON A DOWNWARD TREND. AREAS SOUTH OF I-80 AND NW INDIANA...HAVE ALSO BEEN HARDEST HIT BY SNOW THUS FAR WITH REPORTS AS HIGH AS 2.5 INCHES PER HOUR. THE AREA OF SNOW RESPONSIBLE FOR THOSE INTENSE RATES HAS MOVED EAST. HOWEVER ANOTHER BAND OF SNOW COINCIDING WITH THE FGEN BAND STRETCHES FROM MCHENRY COUNTY THROUGH CHAMPAIGN COUNTY. IT JUST MOVED OVER THE OFFICE HERE AND VSBY DROPPED TO LESS THAN 1/8 OF A MILE WITH HEAVY SNOW. AS SUCH WILL KEEP HEAVY SNOW IN THE FORECAST AS THIS BAND PROGRESSES EASTWARD. HAVE THE BAND PUSHING EAST OF THE CWA BY 5PM CST. THE BACK END OF THE SNOW STRETCHES FROM EASTERN MN TO PEORIA TO DECATUR IL AND IS QUICKLY PUSHING EAST AS WELL. AS SUCH QUICKENED THE END TIME OF SNOW IN THE GRIDS. LEFT TOTALS AS IS WITH GENERALLY 4 TO 8 INCHES ACROSS THE CWA. EXPECTING SLIGHTLY LOWER TOTALS ALONG THE IL/WI STATE LINE AND THEN HIGHER TOTALS ACROSS THE SOUTHERN CWA. WITH THIS BEING A WETTER TYPE SNOW...LEFT BLOWING SNOW OUT OF THE FORECAST. WIND GUSTS PICK UP SOUTH OF I-80 BEHIND THE TROUGH AXIS THIS EVENING. GUSTS UP TO 25 KT ARE EXPECTED...AND THEY DIMINISH BY MORNING. FOR TEMPS...THE PREVIOUS FORECAST WAS RIGHT ON SO DID NOT MAKE TOO MANY CHANGES TO TODAYS TEMPS. FOR TONIGHT...WENT A BIT LOWER THAN GUIDANCE GIVEN THE FRESH SNOW AND CLEARING SKIES. LOWS WILL BE IN THE MID TEENS TO AROUND 20. JEE TUESDAY THROUGH WEDNESDAY... SEMI-ZONAL FLOW OVERHEAD CONTINUES TO PUSH THE 500MB TROUGH AXIS TO THE EAST OF THE REGION TUESDAY...WITH SFC RIDGING BUILDING INTO NORTHERN IL/NORTHWEST IN. THE COMBINATION OF RIDGING...P-CLOUDY SKIES...ALONG WITH MID-LVL TEMPS BEGINNING TO WARM...SHOULD ALLOW SFC TEMPS TO WARM MID/UPR 30S TUE AFTN. A FEW POINTS ALONG THE FAR SOUTHERN CWFA COULD TOUCH 40 DEGREES. THEN WITH THE SEMI-ZONAL FLOW ALLOWING FOR A RELATIVELY FLUID ENVIRONMENT...A WEAK TROUGH PIVOTS EAST FROM THE NORTHERN PLAINS TUE AFTN/EVE...AND BRINGS THICKENING CLOUD COVER BACK TO THE FORECAST AREA. LOCAL MODEL WAS INDICATING SOME SPRINKLES WITH THE WEAK WAVE OVER THE NORTHERN PORTIONS OF THE FORECAST AREA TUE EVE...HOWEVER FEEL TOO MUCH DRY AIR WILL NEED TO BE OVERCOME...SO WILL CONTINUE TO RIDE WITH A DRY FORECAST THROUGH TUE NGT INTO WED AS FRONTAL BOUNDARY SWEEPS EAST ACROSS THE CWFA. SFC RIDGING WILL DEPART EAST...HOWEVER BROAD RIDGING ACROSS THE CENTRAL PLAINS WILL THEN PROVIDE ANOTHER DRY INFLUENCE FOR THE AREA INTO WED. THIS FEATURE WILL THEN SHIFT EAST TOWARDS THE OHIO VALLEY. TEMPS ONLY COOL MARGINALLY TUE NGT ALOFT...SO NOT EXPECTING MUCH COOLING AT THE SFC...THUS HAVE HELD ONTO TEMPS IN THE LOW/MID 20S FOR OVERNIGHT LOWS. THEN FOR WED WITH ANOTHER DRY DAY AND P-CLOUDY SKIES...TEMPS SHUD BE ABLE TO WARM BACK ABOVE FREEZING INTO THE LOW/MID 30S. WEAK MID-LVL RIDGE SLIDES OVERHEAD WED AFTN/EVE...WITH SFC RIDGING KEEPING A SLIGHT INFLUENCE OVER THE CWFA THRU EARLY EVE. THIS SHUD KEEP PRECIP OUT OF THE FORECAST AREA UNTIL LATE WED NGT/EARLY THUR. CONFIDENCE...MEDIUM/HIGH. THURSDAY THROUGH FRIDAY... FOCUS REMAINS ON THE THURSDAY TIMEFRAME...ESPECIALLY WITH THE SUBSTANTIAL WARM-UP THAT CONTINUES TO BE PROGGED BY NUMEROUS FORECAST MODELS. WHILE SOME CORRECTIONS CONTINUE TO TAKE PLACE...WITH RESPECT TO THE PLACEMENT/INTENSITY OF THE DEVELOPING SHORTWAVE AND WARM AIR. 500MB TROUGH REMAINS MORE OF AN ELONGATED SETUP...WITH THE VORT MAX OVER THE NORTHERN ROCKIES DESPITE THE TROUGH STRETCHING SOUTH THROUGH THE FOOTHILLS OF COLORADO EARLY THUR. GUIDANCE CONTINUES TO POINT TOWARDS A SFC WAVE DEVELOPING ON THE LEE-SIDE OF THE ROCKIES NEAR SOUTHEAST COLORADO EARLY THUR. WITH THE DOWNSTREAM RIDGING OVER THE SOUTHEAST CONUS...RETURN FLOW MOISTURE WILL LIKELY STREAM NORTH AHEAD OF THIS DEVELOPING SYSTEM. ENSEMBLES HAVE MAINTAINED A DECENT AGREEMENT WITH PWAT VALUES NEARING 1" FOR AREAS ALONG AND SOUTH OF I-80 IN NORTHERN IL/NORTHWEST IN THUR...WITH STRONG MFLUX CONVERGENCE AT 850MB. THIS COUPLED WITH A VERY ROBUST LLVL JET...AND STRONG INSTABILITY...POINT TOWARDS NOT ONLY THE POTENTIAL FOR MODERATE RAIN GIVEN THE SURGE IN WARM AIR OVER THE FORECAST AREA...BUT ALSO THE POSSIBILITY FOR STRONG THUNDERSTORMS. THE SPC HAS A PORTION OF THE FORECAST AREA...OUTLOOKED FOR POSSIBLE STRONG THUNDERSTORMS. THIS REMAINS MAINLY ALONG AND EAST OF A PONTIAC TO RENSSELAER LINE FOR THE MAIN FOCUS AREA...HOWEVER GIVEN THE CONTINUED UNCERTAINTY ON TIMING/INTENSITY/PLACEMENT OF THE SYSTEM THIS WILL LIKELY BE ADJUSTED OVER TIME. SHORTWAVE THEN SLIDES OVER THE FORECAST AREA THUR EVE...WITH A FRONTAL BOUNDARY BRINGING AN END TO THE MILD AIRMASS AND RETURNING P-TYPE BACK TO LGT SNOW BEFORE ENDING FRI MORNING FROM WEST TO EAST. AFTER TEMPS REACHING INTO THE MID/UPR 40S THUR...FRI HIGHS WILL RETURN TO MORE SEASONAL CONDS IN THE LOW/MID 30S. CONFIDENCE...MEDIUM. SATURDAY THROUGH EARLY NEXT WEEK... THE UPCOMING WEEKEND THROUGH EARLY NEXT WEEK PATTERN IS PROGGED TO RETURN TO WHAT HAS BEEN A COMMON PATTERN OF TROUGHING OVER THE GREAT LAKES REGION...WITH HIGH AMPLITUDE RIDGING PUSHING INTO WESTERN CANADA. TEMPS FOR THE WEEKEND WILL COOL BACK INTO THE 20S FOR HIGHS. THEN GUIDANCE IS INDICATING A COUPLE WEAK MID-LVL WAVES TRAVERSING THE REGION FOR THE SECOND HALF OF THE WEEKEND INTO EARLY NEXT WEEK. CONFIDENCE...MEDIUM/HIGH. && .HYDROLOGY... LATEST MODEL GUIDANCE CONTINUES TO INDICATE ENHANCED CONCERN REGARDING FLOODING POTENTIAL FOR THURSDAY...POSSIBLY LINGERING INTO THE WEEKEND. MORE DETAIL METEOROLOGICAL DISCUSSION IS ABOVE. NO CHANGES REALLY TO THE PREVIOUS HYDROLOGICAL DISCUSSION OTHER THAN SLIGHTLY MORE SNOW AND SNOW WATER EQUIVALENT IS EXPECTED TO BE IN PLACE AFTER TODAY`S SNOW SYSTEM. WILL FRESHEN UP THE ESF AGAIN THIS MORNING BUT NOT PLANNING ANY BIG CHANGES. && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * SOUTHEASTERLY WINDS BECOMING LIGHT AND VARIABLE LATE THIS AFTERNOON/EARLY EVENING...THEN TURNING WESTERLY. * PERIODS OF HEAVY SNOW WITH NEAR WHITEOUT CONDITIONS AT TIMES WITH SNOW RATES IN EXCESS OF AN INCH PER HOUR AT TIMES. * POTENTIAL FOR THUNDERSNOW. BMD //DISCUSSION...UPDATED 18Z... GOING FORECAST SEEMS LARGELY ON TRACK FOR THE TERMINALS WITH MODERATE TO HEAVY SNOW SPREADING NORTHEAST INTO THE REGION EARLY THIS AFTERNOON AND UPSTREAM OBS SHOWING VSBY QUICKLY DROPPING TO 1/4 TO 1/2 MILE. NARROW CORRIDOR ON INSTABILITY AHEAD OF AN APPROACHING F-GEN BAND CURRENTLY MOVING ACROSS THE RIVER STILL APPEARS TO BE THE BEST CHANCE FOR THUNDER TO MOVE NEAR THE TERMINALS...THOUGH STILL FAVORS AREAS JUST SOUTH OF DOWNTOWN CHICAGO. MDW MAY BE CLOSE BUT DO NOT HAVE THE CONFIDENCE IN COVERAGE TO ADD AT THIS TIME. DRIER AIR PUSHES INTO THE AREA BY LATE AFTERNOON/EARLY EVENING AND RATES SHOULD TAPER...THEN FORCING ENDS ABRUPTLY MID EVENING. LINGERING LOW LEVEL MOISTURE WILL RESULT IN LOWER MVFR OR PSBLY IFR CIGS HANGING OUT OVERNIGHT...THOUGH EXPECT VFR CONDITIONS BY AROUND DAYBREAK TOMORROW. BMD //ORD AND MDW CONFIDENCE...UPDATED 20Z... * MEDIUM CONFIDENCE IN WIND SPEEDS/DIRECTION & TIMING WIND SHIFT. * HIGH CONFIDENCE IN VSBY FALLING TO 1/4SM OR LESS WITH SNOW RATES IN EXCESS OF AN INCH PER HOUR AT TIMES. * LOW CONFIDENCE IN THUNDERSNOW AT TERMINALS. BMD //OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z... TUESDAY NIGHT THROUGH WEDNESDAY...PREDOMINANTLY VFR. WEDNESDAY NIGHT...RAIN OR FZRA DEVELOPING. THURSDAY..RAIN/FOG/IFR LIKELY. FZRA POSSIBLE IN THE MORNING. FRIDAY...VFR PROBABLE. SATURDAY AND SUNDAY...SOME POTENTIAL FOR SNOW. IZZI && .MARINE... 300 PM CST HAVE EXTENDED THE GALE WARNING FOR THE CENTRAL PORTIONS OF LAKE MICHIGAN INTO THIS EVENING AS A STRONG SOUTHEASTERLY PRESSURE GRADIENT WILL REMAIN...BETWEEN STRONG HIGH PRESSURE SLOWLY MOVES THROUGH THE NERN CONUS AND A DEEP TROUGH AND STRONG COLD FRONT MOVE THROUGH THE UPPER MISSISSIPPI VALLEY AND INTO THE WESTERN GREAT LAKES REGION. THE COLD FRONT WILL PUSH ACROSS THE LAKE TONIGHT AND A WEAK RIDGE WILL QUICKLY FOLLOW THE FRONT...SETTING UP A PERIOD OF RELATIVELY VARIABLE...BUT WEAKER WINDS OVER THE LAKE. BY TUESDAY NIGHT...A CLIPPER TYPE SYSTEM WILL TRACK THROUGH SRN CANADA...DRAGGING ANOTHER COLD FRONT ACROSS THE PLAINS. AS THE FRONTAL TROUGH APPROACHES THE LAKES...SLY-SWLY WINDS WILL INCREASE TO ARND 30KT...WITH OCCASIONAL GALE FORCE GUSTS POSSIBLE. THE NEXT SIGNIFICANT WEATHER SYSTEM TO IMPACT THE LAKES IS EXPECTED TO DEVELOP OVER THE PLAINS WEDNESDAY NIGHT WITH WEAKER LOW PRESSURE DEVELOPING OVER THE DAKOTAS AND A STRONGER LOW DEVELOPING OVER THE SOUTH HIGH PLAINS. THE SOUTHERN LOW WILL BE THE MAIN SYSTEM OF CONCERN AS IT IS EXPECTED TO DEEPEN RAPIDLY AS IT TRACKS THROUGH ERN WISCONSIN THURSDAY NIGHT...WHILE DRAGGING A STRONG COLD FRONT ACROSS THE LAKE. SWLY WINDS MAY APPROACH GALE FORCE JUST AHEAD OF THE COLD FRONT...AND WILL LIKELY EXCEED GALE FORCE WHILE SHIFTING TO WLY FOLLOWING THE FROPA. KREIN && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011- ILZ012-ILZ019-ILZ020-ILZ021-ILZ032-ILZ039 UNTIL 6 PM MONDAY. WINTER STORM WARNING...ILZ006-ILZ013-ILZ014-ILZ022-ILZ023-ILZ033 UNTIL 9 PM MONDAY. IN...WINTER STORM WARNING...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9 PM MONDAY. LM...GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ868-LMZ870-LMZ872-LMZ874-LMZ876 UNTIL 9 PM MONDAY. && $$ 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
THE FORECAST DISCUSSION FOR THE REMAINDER OF THE WEEK WILL BE
POSTLY SHORTLY.
&& .HYDROLOGY... LATEST MODEL GUIDANCE DOES LOOK MORE WORRISOME THAN IT DID 24 HOURS AGO REGARDING THE FLOOD POTENTIAL THURSDAY...POSSIBLY LINGERING INTO THE WEEKEND. MORE DETAIL METEOROLOGICAL DISCUSSION IS ABOVE. NO CHANGES REALLY TO THE PREVIOUS HYDROLOGICAL DISCUSSION OTHER THAN SLIGHTLY MORE SNOW AND SNOW WATER EQUIVALENT IS EXPECTED TO BE IN PLACE AFTER TODAY`S SNOW SYSTEM. WILL FRESHEN UP THE ESF AGAIN THIS MORNING BUT NOT PLANNING ANY BIG CHANGES. && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * SOUTHEASTERLY WINDS BECOMING LIGHT AND VARIABLE LATE THIS AFTERNOON/EARLY EVENING...THEN TURNING WESTERLY. * PERIODS OF HEAVY SNOW WITH NEAR WHITEOUT CONDITIONS AT TIMES WITH SNOW RATES IN EXCESS OF AN INCH PER HOUR AT TIMES. * POTENTIAL FOR THUNDERSNOW. BMD //DISCUSSION...UPDATED 18Z... GOING FORECAST SEEMS LARGELY ON TRACK FOR THE TERMINALS WITH MODERATE TO HEAVY SNOW SPREADING NORTHEAST INTO THE REGION EARLY THIS AFTERNOON AND UPSTREAM OBS SHOWING VSBY QUICKLY DROPPING TO 1/4 TO 1/2 MILE. NARROW CORRIDOR ON INSTABILITY AHEAD OF AN APPROACHING F-GEN BAND CURRENTLY MOVING ACROSS THE RIVER STILL APPEARS TO BE THE BEST CHANCE FOR THUNDER TO MOVE NEAR THE TERMINALS...THOUGH STILL FAVORS AREAS JUST SOUTH OF DOWNTOWN CHICAGO. MDW MAY BE CLOSE BUT DO NOT HAVE THE CONFIDENCE IN COVERAGE TO ADD AT THIS TIME. DRIER AIR PUSHES INTO THE AREA BY LATE AFTERNOON/EARLY EVENING AND RATES SHOULD TAPER...THEN FORCING ENDS ABRUPTLY MID EVENING. LINGERING LOW LEVEL MOISTURE WILL RESULT IN LOWER MVFR OR PSBLY IFR CIGS HANGING OUT OVERNIGHT...THOUGH EXPECT VFR CONDITIONS BY AROUND DAYBREAK TOMORROW. BMD //ORD AND MDW CONFIDENCE...UPDATED 20Z... * MEDIUM CONFIDENCE IN WIND SPEEDS/DIRECTION & TIMING WIND SHIFT. * HIGH CONFIDENCE IN VSBY FALLING TO 1/4SM OR LESS WITH SNOW RATES IN EXCESS OF AN INCH PER HOUR AT TIMES. * LOW CONFIDENCE IN THUNDERSNOW AT TERMINALS. BMD //OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z... TUESDAY NIGHT THROUGH WEDNESDAY...PREDOMINANTLY VFR. WEDNESDAY NIGHT...RAIN OR FZRA DEVELOPING. THURSDAY..RAIN/FOG/IFR LIKELY. FZRA POSSIBLE IN THE MORNING. FRIDAY...VFR PROBABLE. SATURDAY AND SUNDAY...SOME POTENTIAL FOR SNOW. IZZI && .MARINE... 300 PM CST HAVE EXTENDED THE GALE WARNING FOR THE CENTRAL PORTIONS OF LAKE MICHIGAN INTO THIS EVENING AS A STRONG SOUTHEASTERLY PRESSURE GRADIENT WILL REMAIN...BETWEEN STRONG HIGH PRESSURE SLOWLY MOVES THROUGH THE NERN CONUS AND A DEEP TROUGH AND STRONG COLD FRONT MOVE THROUGH THE UPPER MISSISSIPPI VALLEY AND INTO THE WESTERN GREAT LAKES REGION. THE COLD FRONT WILL PUSH ACROSS THE LAKE TONIGHT AND A WEAK RIDGE WILL QUICKLY FOLLOW THE FRONT...SETTING UP A PERIOD OF RELATIVELY VARIABLE...BUT WEAKER WINDS OVER THE LAKE. BY TUESDAY NIGHT...A CLIPPER TYPE SYSTEM WILL TRACK THROUGH SRN CANADA...DRAGGING ANOTHER COLD FRONT ACROSS THE PLAINS. AS THE FRONTAL TROUGH APPROACHES THE LAKES...SLY-SWLY WINDS WILL INCREASE TO ARND 30KT...WITH OCCASIONAL GALE FORCE GUSTS POSSIBLE. THE NEXT SIGNIFICANT WEATHER SYSTEM TO IMPACT THE LAKES IS EXPECTED TO DEVELOP OVER THE PLAINS WEDNESDAY NIGHT WITH WEAKER LOW PRESSURE DEVELOPING OVER THE DAKOTAS AND A STRONGER LOW DEVELOPING OVER THE SOUTH HIGH PLAINS. THE SOUTHERN LOW WILL BE THE MAIN SYSTEM OF CONCERN AS IT IS EXPECTED TO DEEPEN RAPIDLY AS IT TRACKS THROUGH ERN WISCONSIN THURSDAY NIGHT...WHILE DRAGGING A STRONG COLD FRONT ACROSS THE LAKE. SWLY WINDS MAY APPROACH GALE FORCE JUST AHEAD OF THE COLD FRONT...AND WILL LIKELY EXCEED GALE FORCE WHILE SHIFTING TO WLY FOLLOWING THE FROPA. KREIN && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011- ILZ012-ILZ019-ILZ020-ILZ021-ILZ032-ILZ039 UNTIL 6 PM MONDAY. WINTER STORM WARNING...ILZ006-ILZ013-ILZ014-ILZ022-ILZ023-ILZ033 UNTIL 9 PM MONDAY. IN...WINTER STORM WARNING...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9 PM MONDAY. LM...GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ868-LMZ870-LMZ872-LMZ874-LMZ876 UNTIL 9 PM MONDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 PM MONDAY. && $$ 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
NWS CHICAGO/ROMEOVILLE IL
158 PM CST MON FEB 17 2014 .DISCUSSION... 330 AM CST SHORT TERM (THROUGH TONIGHT)... MAIN CONCERNS ARE WITH INCREASED POTENTIAL FOR A PERIOD OF HEAVY SNOW THIS AFTERNOON FOR THE ENTIRE CWA WHICH COULD HAVE SIGNIFICANT IMPACTS WITH WHITE OUT CONDITIONS UNDER POSSIBLE TWO TO THREE INCH PER HOUR SNOWFALL RATES SOME OF WHICH COULD FALL UNDER CONVECTIVE ELEMENTS...WITH AREA WIDE 4 TO 8 INCHES LIKELY AND SOME ISOLATED AMOUNTS NEAR 10 INCHES DEFINITELY NOT OUT OF THE QUESTION. IMPRESSIVE STRONG STORM ANTICIPATED TO TAKE SHAPE OVER THE AREA LATER TODAY CAN BE OBSERVED ON SATELLITE IMAGERY...WITH MID/UPPER LEVEL TROUGH CURRENTLY PUSHING EAST THROUGH THE NORTHERN PLAINS. OUT AHEAD OF THIS SYSTEM...LATEST RAP ANALYSIS DEPICTING STRONG ISENTROPIC ASCENT OCCURRING ACROSS THE ENTIRE REGION INCLUDING LOCALLY OVER THE CWA. THIS HAS RESULTED IN PERSISTENT MID/HIGH LEVEL CLOUD COVER TO STREAM OUT AHEAD OF THIS SYSTEM...WITH CURRENT RADAR IMAGERY LIGHTING UP WITH SOME DECENT RETURNS. ALTHOUGH RATHER DRY AIR IN PLACE HAS LIMITED ANY PRECIP TO REACH THE SURFACE AND ANTICIPATE FOR THIS TO FURTHER BE THE CASE OVER THE NEXT COUPLE OF HOURS. WHAT COULD BE EXPECTED IN THE NEAR TERM ARE SOME ISOLATED FLURRIES PRIMARILY OVER THE NORTHWEST HALF OF THE CWA...WITH RFD CURRENTLY REPORTING 9 MILES IN LIGHT SNOW. ISENTROPIC ASCENT WILL CONTINUE THIS MORNING...WITH SHORT TERM GUIDANCE HINTING AT THE POSSIBILITY FOR FURTHER PRECIP DEVELOPMENT ENTERING THE SOUTHWEST CWA JUST AFTER THE 12Z TIME FRAME. PREVIOUSLY DISCUSSED WARMING/WARM WEDGE STILL ANTICIPATED HERE THIS MORNING AND COULD INITIALLY BRING A WINTRY MIX BUT STAYING CONFINED TO THE SOUTHERN HALF OF THE CWA...PRIMARILY SOUTH OF THE I80 CORRIDOR. IF ANYTHING WERE TO OCCUR DURING THIS TIME FRAME...ANTICIPATE IT TO BE ON THE LIGHTER SIDE WITH THE PREVIOUSLY MENTIONED DRIER AIR STILL NEEDING TO BE OVERCOME. NONETHELESS...WITH AN ANTICIPATED SLOWING TREND WITH THE EVOLUTION OF TODAY`S SYSTEM...THIS WINTRY MIX COULD BE MORE PREVALENT THAN PREVIOUSLY THOUGHT TO START THE PERIOD. SO HAVE INCLUDED CHANCE ZR/IP IN THE GRIDS THROUGH 15Z. CAN MAKE OUT TWO SEPARATE PIECES OF STRONG ENERGY TRAVERSING THE MID LEVEL FLOW...NOW WITH ALL GUIDANCE IN STRONG AGREEMENT WITH THE EVOLUTION OF THIS ENERGY AS IT APPROACHES THE REGION. ABOUT THE ONLY DIFFERENCE AT THIS TIME IS SOME SLIGHT TIMING DIFFERENCES WITH THE APPROACH OF THE BETTER FORCING/PRECIP LATER TODAY. A CONTINUED SLOWER TREND HAS BEEN THE PREFERRED TREND HERE THIS MORNING...AND HAVE DELAYED HIGHEST POPS TODAY. ALTHOUGH DID NOT OVERLY STRAY TOO MUCH WITH THE PREVIOUSLY MENTIONED ISENTROPIC ASCENT AND POTENTIAL PRECIP OUT AHEAD OF IT. HAVE CONTINUED THE MENTION IN THE GRIDS FOR A MIX OF SLEET FOR LATER IN THE MORNING...MAINLY FOR THE SOUTHERN TIER OF COUNTIES. ALTHOUGH THERMAL PROFILES WOULD BE SUPPORTIVE OF THIS WINTRY MIX CONTINUING...HAVE LIMITED MENTION OF THIS MIX AS BETTER FORCING SHOULD BE ARRIVING DURING THIS TIME. WHATEVER LINGERING WARM WEDGE IN THE COLUMN WILL QUICKLY COOL THE COLUMN TO THE WET BULB AS STRONG DYNAMIC FORCING ARRIVES...WITH ANY MIX QUICKLY CHANGING OVER TO ALL SNOW. ONCE AGAIN...ALL GUIDANCE POINTING AT SIGNIFICANT SNOWFALL RATES BEGINNING AT SOON AS LATE MORNING FOR THE WESTERN CWA. TWO PIECES OF ENERGY WILL PHASE TOGETHER BY EARLY AFTERNOON...WITH THIS MID/UPPER LEVEL TROUGH BECOMING NEGATIVELY TILTED. AS THIS OCCURS...ATTENDANT LOW TO DEEPEN AS IT MOVES THROUGH CENTRAL ILLINOIS WITH 850MB LOW REALLY BEGINNING TO TAKE SHAPE. STRONG DYNAMICAL FORCING ASSOCIATED WITH THIS MID LEVEL TROUGH AND SIGNIFICANT HEIGHT FALLS WILL ALLOW FORCING TO SWING THROUGH THE CWA BY LATE MORNING INTO THE EARLY AFTERNOON. ASSOCIATED FRONTOGENETICAL FORCING WILL LIKEWISE PUSH EAST THROUGH THE AREA THIS AFTERNOON...WITH THE PRESENCE OF NEGATIVE EPV. THIS PRESENCE OF BOTH SLANTWISE AND UPRIGHT MOTIONS ARE LEADING FOR SOME REALLY IMPRESSIVE VERTICAL MOTION...WITH FORECAST OMEGA AMONG ALL GUIDANCE SOME OF THE HIGHEST IVE OBSERVED IN SOME TIME. THE STRONGEST VERTICAL MOTIONS ARE EXPECTED TO PUSH EAST TO WEST ACROSS THE CWA INTO THE EARLY AFTERNOON TIME FRAME AND CONTINUING THROUGH MID/LATE AFTERNOON...WITH FORCING CENTERED RIGHT IN THE MIDDLE OF THE CWA. ALTHOUGH CURRENT FORECAST SNOW TOTALS ARE THE HIGHEST IN THESE LOCATIONS...TOTALS DONT STRAY TOO MUCH FROM THE AMOUNTS ACROSS THE REMAINING CWA. THIS IS IN DUE TO PART TO HOW UNSTABLE THIS SYSTEM WILL BE...INCLUDING CONVECTIVE INSTABILITY. BOTH NAM/GFS SHOWING IMPRESSIVE MUCAPE TO PUSH NORTHEAST THROUGH THE CWA AS EARLY AS MID MORNING...AND THE BEGINNING STAGES OF THIS CAN ALREADY BE OBSERVED TO OUR WEST/SOUTHWEST WITH LATEST RAP ANALYSIS DEPICTING 100-200 J/KG OVER IOWA/MISSOURI/KANSAS. WITH SREF GUIDANCE INDICATING HIGH PROBABILITIES OF AT LEAST 50-100 J/KG OF MUCAPE TO MOVE OVERHEAD LATER TODAY...FEEL THAT THE NAM/GFS SOLUTION OF 100 TO ALMOST 300 J/KG IS NOT OF THE QUESTION. THE PRESENCE OF THIS STRONG FORCING...STRONG INSTABILITY AND ABUNDANCE OF MOISTURE NOT ONLY LIKELY BEING PRESENT BUT ALSO COMING TOGETHER...HAS STEERED THE FORECAST SIGNIFICANTLY MORE PESSIMISTIC THIS MORNING. HEAVIEST SNOW...WHICH WILL FALL WITH HIGH INTENSITIES AND POSSIBLY AT A RATE OF TWO TO THREE INCHES PER HOUR AT TIMES SHOULD ARRIVE THE FAR WESTERN CWA BY MID/LATE MORNING...AND THEN SPREADING EAST THROUGH THE REMAINING CWA BY EARLY AFTERNOON. EXPECT THESE HIGH SNOWFALL INTENSITIES THROUGH MID TO LATE AFTERNOON...AND POSSIBLY CONTINUE INTO THE EARLY EVENING FOR THE EASTERN THIRD OF THE CWA. THIS HEAVY SNOW WILL QUICKLY ACCUMULATE ON ROADS WITH NEAR VISIBILITY LIKELY UNDER THIS HEAVY SNOW...CREATING VERY HAZARDOUS CONDITIONS. AS WAS MENTIONED PREVIOUSLY...THE HIGHEST TOTALS ARE IN THE CWA ALIGNED WITH THE BETTER FORCING...BUT FEEL THAT ANY LACKING FORCING WILL BE SUPPLEMENTED WITH THE CONVECTIVE NATURE OF THIS SYSTEM. CONVECTIVE ALLOWING MODELS INDICATE THE PRESENCE OF THUNDER BREAKING OUT BY EARLY AFTERNOON. ALTHOUGH GUIDANCE IS HINTING THAT THIS WILL BE MORE PREFERRED ACROSS THE SOUTHERN CWA...WITH GUIDANCE INDICATING INSTABILITY INTO SOUTHERN WISCONSIN...HAVE INCLUDED A CHANCE FOR THUNDER IN THE GRIDS FOR THE ENTIRE CWA. ITS THESE CONVECTIVE ELEMENTS WHICH COULD SUPPLEMENT HIGHER RATES AND RESULTANT SNOWFALL TOTALS. SO FOR THE WARNING ISSUED OVERNIGHT...WILL HAVE AREA WIDE 4 TO 8 INCHES WITH THE POSSIBILITY OF SLIGHTLY HIGHER AMOUNTS NEAR 10 INCHES. IF THESE CONVECTIVE ELEMENTS WERE TO MATERIALIZE...THEN AREAS DEFINITELY COULD OBSERVE THESE HIGHER AMOUNTS. ALSO...ITS POSSIBLE THAT THESE AMOUNTS COULD BE OBSERVED IN A 4-6 HOUR WINDOW. HAVE THE WARNING ENDING EARLY THIS EVENING FOR THE WESTERN CWA AND THEN AT 3Z LATER THIS EVENING FOR THE EASTERN CWA. IF LATER GUIDANCE THIS MORNING CONTINUES TO SUPPORT CURRENT THINKING...SITUATION FORECAST TO UNFOLD LATER THIS AFTERNOON WILL DEFINITELY BE SOMETHING TO NOT TAKE LIGHTLY. RODRIGUEZ LONG TERM (TUESDAY THROUGH SUNDAY)... FAST ON THE HEELS OF TODAY`S DEPARTING SYSTEM WILL BE ANOTHER NORTHERN STREAM SYSTEM TRACKING ACROSS SOUTHERN CANADA. VERY STRONG WARM AIR ADVECTION WILL BE UNDERWAY ALOFT TUES MORNING AND EVENTUALLY DEVELOPING AT THE SURFACE AS SOUTHERLY WINDS PICK UP. DEEP AND FRESHLY RELOADED SNOW COVER OVER THE AREA WILL UNDOUBTEDLY RETARD THE WARM UP...BUT STILL THINK TEMPS SHOULD MANAGE TO CLIMB ABOVE FREEZING MOST AREAS FOR THE FIRST TIME IN WEEKS TUES AFTERNOON. WEAK COLD FRONT MOVES THROUGH TUESDAY EVENING WITH LITTLE FANFARE AND BARELY TIME FOR MUCH COLD AIR TO SEEP SOUTHWARD BEFORE WARM AIR ADVECTION BEGINS AGAIN LATER WEDNESDAY IN ADVANCE OF LATE WEDNESDAY NIGHT INTO THURSDAY`S WELL ADVERTISED BIG HULLABALOO. NOT SURPRISINGLY GIVEN THE COMPLEXITY OF THE PATTERN AND DEALING WITH PHASING ISSUES...MODELS HAVE FLOPPED BACK FROM THEIR PREVIOUS FLIP WITH MORE EMPHASIS ON A STRENGTHENING SOUTHERN LOW LIFTING NORTHEAST INTO THE GREAT LAKES. STILL SOME DIFFERENCES IN STRENGTH AND EXACT TRACK...BUT ECMWF/GFS NOW AGREE ON TAKING A SFC LOW OVER NORTHERN MISSOURI 18Z THURS NORTHEAST TO THE UPPER GREAT LAKES BY THURSDAY NIGHT...WITH CONSIDERABLE DEEPEN OF THE LOW ALONG THE WAY. ECMWF AND 06Z NAM ARE STRONGER AND A BIT FARTHER NORTHWEST...BUT NAM/GFS/ECMWF ALL HAVE THE SAME GENERAL IDEA. FIRST FORECAST ISSUE WILL BE WEDNESDAY NIGHT AS INITIAL BATCH OF WAA PRECIP BREAKS OUT AND LIFTS NORTH ACROSS THE AREA. MODEL QPF REMAINS FAIRLY HIGH AND WITH SOME ELEVATED INSTABILITY ALSO EVIDENT IN THE MODELS...CERTAINLY ENOUGH TO WARRANT A CONTINUED SLIGHT CHANCE MENTION OF THUNDERSTORMS. THE BIGGEST PROBLEM WED NIGHT WILL BE HOW FAST THE 2M TEMPS WARM UP. WHILE VERY STRONG WAA WILL BE TAKING PLACE ALOFT...INITIALLY EASTERLY WINDS OVER THE AREA AND DEEP SNOW PACK COULD ALLOW FOR A RATHER PROLONGED PERIOD OF FREEZING RAIN AND AN ICING THREAT DEPENDING ON SFC TEMPS. MANY OF THE MODEL SUGGEST A SURGE OF WARM LATE WEDNESDAY NIGHT...ESPECIALLY SOUTHERN CWA...BUT ITS GOING TO BE CLOSE. ONLY A MATTER OF A COUPLE DEGREES COULD MEAN THE DIFFERENCE BETWEEN A SIGNIFICANT ICING PROBLEM AND ALL RAIN AND THIS FAR OUT IT REALLY IS ANYONE`S GUESS WHAT SIDE OF 32F ANY ONE GIVEN AREA WILL END UP ON AS THE RAIN FALLS. CERTAINLY FARTHER NORTH WOULD STAND THE BETTER CHANCE OF FREEZING RAIN...BUT THE ICING POTENTIAL CANNOT BE RULED OUT EVEN OVER SOUTHERN PORTIONS OF THE CWA. THIS LATEST SWING IN THE MODELS TOWARD A MORE AMPLIFIED SOUTHERN LOW TRACKING NORTH IS BAD NEWS FOR IN THE HYDROLOGY DEPARTMENT. WHILE NOT AS HORRIFYING AS THE NIGHTMARE SCENARIO THE ECMWF HAD BEEN PAINTING A COUPLE DAYS AGO WITH 50 AND NEAR 60F DEWPOINTS TO THE WISCONSIN LINE...THE LATEST GUIDANCE DOES DRAG THE 40F ISODROSOTHERM FAR NORTH INTO THE AREA ON THURSDAY...WITH EVEN SOME 50F DEWPOINTS FAR SOUTHERN CWA. THE HIGHER THE DEWPOINTS THE MORE RAPID THE SNOW MELT WILL BE AND THE MORE OF A PROBLEM ANY MODERATE TO HEAVY RAIN THAT FALLS WILL POSE THURSDAY. TEMPS LOOK TO CLIMB SAFELY ABOVE FREEZING THURS AM EVEN NORTH TO THE WI BORDER ENDING THE FRZ RAIN THREAT...BUT WITH PWATS PROGGED TO CLIMB TO OVER AN INCH (200-250% OF NORMAL) THURSDAY THE POTENTIAL WILL EXIST FOR HEAVY RAINFALL. HAVE ALREADY BEEN HARPING ON ALL THE HYDRO CONCERNS IN THE ESF ISSUED FRIDAY AND UPDATED OVER THE WEEKEND AND REALLY NO BIG CHANGES IN THINKING AT THIS POINT OTHER THAN TO SAY THE FLOOD POTENTIAL IS LOOKING MORE OMINOUS THAN IT DID 24 HOURS AGO. STRONG COLD FRONT LOOKS TO SWEEP THROUGH THURSDAY EVENING BRINGING AN END TO THE RAIN AND POSSIBLE THUNDERSTORMS AND ALLOWING DRIER AND COLDER AIR TO FILTER INTO THE REGION. WHILE COLDER AIR FILTERS IN FOR THE WEEKEND WITH MEDIUM RANGE MODELS SUGGESTING ONE OR TWO SYSTEM COULD AFFECT THE REGION WITH WHAT WOULD PROBABLY BE SOME SNOWFALL. TIMING AND TRACK OF THESE LOWER AMPLITUDE WAVES ARE ALL OVER THE PLACE IN THE MODELS SO ONLY CARRYING LOW CHANCES POPS FOR NOW. IZZI && .HYDROLOGY... LATEST MODEL GUIDANCE DOES LOOK MORE WORRISOME THAN IT DID 24 HOURS AGO REGARDING THE FLOOD POTENTIAL THURSDAY...POSSIBLY LINGERING INTO THE WEEKEND. MORE DETAIL METEOROLOGICAL DISCUSSION IS ABOVE. NO CHANGES REALLY TO THE PREVIOUS HYDROLOGICAL DISCUSSION OTHER THAN SLIGHTLY MORE SNOW AND SNOW WATER EQUIVALENT IS EXPECTED TO BE IN PLACE AFTER TODAY`S SNOW SYSTEM. WILL FRESHEN UP THE ESF AGAIN THIS MORNING BUT NOT PLANNING ANY BIG CHANGES. && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * SOUTHEASTERLY WINDS BECOMING LIGHT AND VARIABLE LATE THIS AFTERNOON/EARLY EVENING...THEN TURNING WESTERLY. * PERIODS OF HEAVY SNOW WITH NEAR WHITEOUT CONDITIONS AT TIMES WITH SNOW RATES IN EXCESS OF AN INCH PER HOUR AT TIMES. * POTENTIAL FOR THUNDERSNOW. BMD //DISCUSSION...UPDATED 18Z... GOING FORECAST SEEMS LARGELY ON TRACK FOR THE TERMINALS WITH MODERATE TO HEAVY SNOW SPREADING NORTHEAST INTO THE REGION EARLY THIS AFTERNOON AND UPSTREAM OBS SHOWING VSBY QUICKLY DROPPING TO 1/4 TO 1/2 MILE. NARROW CORRIDOR ON INSTABILITY AHEAD OF AN APPROACHING F-GEN BAND CURRENTLY MOVING ACROSS THE RIVER STILL APPEARS TO BE THE BEST CHANCE FOR THUNDER TO MOVE NEAR THE TERMINALS...THOUGH STILL FAVORS AREAS JUST SOUTH OF DOWNTOWN CHICAGO. MDW MAY BE CLOSE BUT DO NOT HAVE THE CONFIDENCE IN COVERAGE TO ADD AT THIS TIME. DRIER AIR PUSHES INTO THE AREA BY LATE AFTERNOON/EARLY EVENING AND RATES SHOULD TAPER...THEN FORCING ENDS ABRUPTLY MID EVENING. LINGERING LOW LEVEL MOISTURE WILL RESULT IN LOWER MVFR OR PSBLY IFR CIGS HANGING OUT OVERNIGHT...THOUGH EXPECT VFR CONDITIONS BY AROUND DAYBREAK TOMORROW. BMD //ORD AND MDW CONFIDENCE...UPDATED 20Z... * MEDIUM CONFIDENCE IN WIND SPEEDS/DIRECTION & TIMING WIND SHIFT. * HIGH CONFIDENCE IN VSBY FALLING TO 1/4SM OR LESS WITH SNOW RATES IN EXCESS OF AN INCH PER HOUR AT TIMES. * LOW CONFIDENCE IN THUNDERSNOW AT TERMINALS. BMD //OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z... TUESDAY NIGHT THROUGH WEDNESDAY...PREDOMINANTLY VFR. WEDNESDAY NIGHT...RAIN OR FZRA DEVELOPING. THURSDAY..RAIN/FOG/IFR LIKELY. FZRA POSSIBLE IN THE MORNING. FRIDAY...VFR PROBABLE. SATURDAY AND SUNDAY...SOME POTENTIAL FOR SNOW. IZZI && .MARINE... 324 AM CST HAVE HOISTED A GALE WARNING FOR A LARGE PORTION OF CENTRAL LAKE MICHIGAN FOR TODAY. THE DEEPER SFC LOW IN THE MODELS SHOULD RESULT IN A PERIOD OF SOUTHEAST GALES THIS MORNING INTO THE EARLY AFTERNOON BEFORE THE BAGGIER PRESSURE GRADIENT APPROACHES THE LAKE ASSOCIATED WITH THE INVERTED TROUGH NORTH OF THE LOW TRACKING ACROSS DOWNSTATE IL AND IN. BRIEF SHOT OF WESTERLY WINDS TONIGHT IN THE WAKE OF THE TROUGH AND DEPARTING LOW BEFORE SOUTHERLY WINDS BEGIN TO REALLY CRANK UP AGAIN ON TUESDAY AS ANOTHER STRONG LOW TRACK EAST ACROSS THE SOUTHERN CANADIAN PRAIRIES. COULD BE BORDERLINE SOUTHERLY GALES ON TUESDAY AFTERNOON AS WELL...BUT FOR NOW JUST STUCK WITH OCNL GALE WORDING IN THE GLF AND WILL LET NEXT SHIFT GET ANOTHER LOOK BEFORE DECIDING ON POSSIBLE GALE HEADLINES FOR TUESDAY. IZZI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011- ILZ012-ILZ019-ILZ020-ILZ021-ILZ032-ILZ039 UNTIL 6 PM MONDAY. WINTER STORM WARNING...ILZ006-ILZ013-ILZ014-ILZ022-ILZ023-ILZ033 UNTIL 9 PM MONDAY. IN...WINTER STORM WARNING...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9 PM MONDAY. LM...GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ868-LMZ870-LMZ872-LMZ874-LMZ876 UNTIL 9 PM MONDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 PM MONDAY. && $$ 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
NWS CHICAGO/ROMEOVILLE IL
1210 PM CST MON FEB 17 2014 .DISCUSSION... 330 AM CST SHORT TERM (THROUGH TONIGHT)... MAIN CONCERNS ARE WITH INCREASED POTENTIAL FOR A PERIOD OF HEAVY SNOW THIS AFTERNOON FOR THE ENTIRE CWA WHICH COULD HAVE SIGNIFICANT IMPACTS WITH WHITE OUT CONDITIONS UNDER POSSIBLE TWO TO THREE INCH PER HOUR SNOWFALL RATES SOME OF WHICH COULD FALL UNDER CONVECTIVE ELEMENTS...WITH AREA WIDE 4 TO 8 INCHES LIKELY AND SOME ISOLATED AMOUNTS NEAR 10 INCHES DEFINITELY NOT OUT OF THE QUESTION. IMPRESSIVE STRONG STORM ANTICIPATED TO TAKE SHAPE OVER THE AREA LATER TODAY CAN BE OBSERVED ON SATELLITE IMAGERY...WITH MID/UPPER LEVEL TROUGH CURRENTLY PUSHING EAST THROUGH THE NORTHERN PLAINS. OUT AHEAD OF THIS SYSTEM...LATEST RAP ANALYSIS DEPICTING STRONG ISENTROPIC ASCENT OCCURRING ACROSS THE ENTIRE REGION INCLUDING LOCALLY OVER THE CWA. THIS HAS RESULTED IN PERSISTENT MID/HIGH LEVEL CLOUD COVER TO STREAM OUT AHEAD OF THIS SYSTEM...WITH CURRENT RADAR IMAGERY LIGHTING UP WITH SOME DECENT RETURNS. ALTHOUGH RATHER DRY AIR IN PLACE HAS LIMITED ANY PRECIP TO REACH THE SURFACE AND ANTICIPATE FOR THIS TO FURTHER BE THE CASE OVER THE NEXT COUPLE OF HOURS. WHAT COULD BE EXPECTED IN THE NEAR TERM ARE SOME ISOLATED FLURRIES PRIMARILY OVER THE NORTHWEST HALF OF THE CWA...WITH RFD CURRENTLY REPORTING 9 MILES IN LIGHT SNOW. ISENTROPIC ASCENT WILL CONTINUE THIS MORNING...WITH SHORT TERM GUIDANCE HINTING AT THE POSSIBILITY FOR FURTHER PRECIP DEVELOPMENT ENTERING THE SOUTHWEST CWA JUST AFTER THE 12Z TIME FRAME. PREVIOUSLY DISCUSSED WARMING/WARM WEDGE STILL ANTICIPATED HERE THIS MORNING AND COULD INITIALLY BRING A WINTRY MIX BUT STAYING CONFINED TO THE SOUTHERN HALF OF THE CWA...PRIMARILY SOUTH OF THE I80 CORRIDOR. IF ANYTHING WERE TO OCCUR DURING THIS TIME FRAME...ANTICIPATE IT TO BE ON THE LIGHTER SIDE WITH THE PREVIOUSLY MENTIONED DRIER AIR STILL NEEDING TO BE OVERCOME. NONETHELESS...WITH AN ANTICIPATED SLOWING TREND WITH THE EVOLUTION OF TODAY`S SYSTEM...THIS WINTRY MIX COULD BE MORE PREVALENT THAN PREVIOUSLY THOUGHT TO START THE PERIOD. SO HAVE INCLUDED CHANCE ZR/IP IN THE GRIDS THROUGH 15Z. CAN MAKE OUT TWO SEPARATE PIECES OF STRONG ENERGY TRAVERSING THE MID LEVEL FLOW...NOW WITH ALL GUIDANCE IN STRONG AGREEMENT WITH THE EVOLUTION OF THIS ENERGY AS IT APPROACHES THE REGION. ABOUT THE ONLY DIFFERENCE AT THIS TIME IS SOME SLIGHT TIMING DIFFERENCES WITH THE APPROACH OF THE BETTER FORCING/PRECIP LATER TODAY. A CONTINUED SLOWER TREND HAS BEEN THE PREFERRED TREND HERE THIS MORNING...AND HAVE DELAYED HIGHEST POPS TODAY. ALTHOUGH DID NOT OVERLY STRAY TOO MUCH WITH THE PREVIOUSLY MENTIONED ISENTROPIC ASCENT AND POTENTIAL PRECIP OUT AHEAD OF IT. HAVE CONTINUED THE MENTION IN THE GRIDS FOR A MIX OF SLEET FOR LATER IN THE MORNING...MAINLY FOR THE SOUTHERN TIER OF COUNTIES. ALTHOUGH THERMAL PROFILES WOULD BE SUPPORTIVE OF THIS WINTRY MIX CONTINUING...HAVE LIMITED MENTION OF THIS MIX AS BETTER FORCING SHOULD BE ARRIVING DURING THIS TIME. WHATEVER LINGERING WARM WEDGE IN THE COLUMN WILL QUICKLY COOL THE COLUMN TO THE WET BULB AS STRONG DYNAMIC FORCING ARRIVES...WITH ANY MIX QUICKLY CHANGING OVER TO ALL SNOW. ONCE AGAIN...ALL GUIDANCE POINTING AT SIGNIFICANT SNOWFALL RATES BEGINNING AT SOON AS LATE MORNING FOR THE WESTERN CWA. TWO PIECES OF ENERGY WILL PHASE TOGETHER BY EARLY AFTERNOON...WITH THIS MID/UPPER LEVEL TROUGH BECOMING NEGATIVELY TILTED. AS THIS OCCURS...ATTENDANT LOW TO DEEPEN AS IT MOVES THROUGH CENTRAL ILLINOIS WITH 850MB LOW REALLY BEGINNING TO TAKE SHAPE. STRONG DYNAMICAL FORCING ASSOCIATED WITH THIS MID LEVEL TROUGH AND SIGNIFICANT HEIGHT FALLS WILL ALLOW FORCING TO SWING THROUGH THE CWA BY LATE MORNING INTO THE EARLY AFTERNOON. ASSOCIATED FRONTOGENETICAL FORCING WILL LIKEWISE PUSH EAST THROUGH THE AREA THIS AFTERNOON...WITH THE PRESENCE OF NEGATIVE EPV. THIS PRESENCE OF BOTH SLANTWISE AND UPRIGHT MOTIONS ARE LEADING FOR SOME REALLY IMPRESSIVE VERTICAL MOTION...WITH FORECAST OMEGA AMONG ALL GUIDANCE SOME OF THE HIGHEST IVE OBSERVED IN SOME TIME. THE STRONGEST VERTICAL MOTIONS ARE EXPECTED TO PUSH EAST TO WEST ACROSS THE CWA INTO THE EARLY AFTERNOON TIME FRAME AND CONTINUING THROUGH MID/LATE AFTERNOON...WITH FORCING CENTERED RIGHT IN THE MIDDLE OF THE CWA. ALTHOUGH CURRENT FORECAST SNOW TOTALS ARE THE HIGHEST IN THESE LOCATIONS...TOTALS DONT STRAY TOO MUCH FROM THE AMOUNTS ACROSS THE REMAINING CWA. THIS IS IN DUE TO PART TO HOW UNSTABLE THIS SYSTEM WILL BE...INCLUDING CONVECTIVE INSTABILITY. BOTH NAM/GFS SHOWING IMPRESSIVE MUCAPE TO PUSH NORTHEAST THROUGH THE CWA AS EARLY AS MID MORNING...AND THE BEGINNING STAGES OF THIS CAN ALREADY BE OBSERVED TO OUR WEST/SOUTHWEST WITH LATEST RAP ANALYSIS DEPICTING 100-200 J/KG OVER IOWA/MISSOURI/KANSAS. WITH SREF GUIDANCE INDICATING HIGH PROBABILITIES OF AT LEAST 50-100 J/KG OF MUCAPE TO MOVE OVERHEAD LATER TODAY...FEEL THAT THE NAM/GFS SOLUTION OF 100 TO ALMOST 300 J/KG IS NOT OF THE QUESTION. THE PRESENCE OF THIS STRONG FORCING...STRONG INSTABILITY AND ABUNDANCE OF MOISTURE NOT ONLY LIKELY BEING PRESENT BUT ALSO COMING TOGETHER...HAS STEERED THE FORECAST SIGNIFICANTLY MORE PESSIMISTIC THIS MORNING. HEAVIEST SNOW...WHICH WILL FALL WITH HIGH INTENSITIES AND POSSIBLY AT A RATE OF TWO TO THREE INCHES PER HOUR AT TIMES SHOULD ARRIVE THE FAR WESTERN CWA BY MID/LATE MORNING...AND THEN SPREADING EAST THROUGH THE REMAINING CWA BY EARLY AFTERNOON. EXPECT THESE HIGH SNOWFALL INTENSITIES THROUGH MID TO LATE AFTERNOON...AND POSSIBLY CONTINUE INTO THE EARLY EVENING FOR THE EASTERN THIRD OF THE CWA. THIS HEAVY SNOW WILL QUICKLY ACCUMULATE ON ROADS WITH NEAR VISIBILITY LIKELY UNDER THIS HEAVY SNOW...CREATING VERY HAZARDOUS CONDITIONS. AS WAS MENTIONED PREVIOUSLY...THE HIGHEST TOTALS ARE IN THE CWA ALIGNED WITH THE BETTER FORCING...BUT FEEL THAT ANY LACKING FORCING WILL BE SUPPLEMENTED WITH THE CONVECTIVE NATURE OF THIS SYSTEM. CONVECTIVE ALLOWING MODELS INDICATE THE PRESENCE OF THUNDER BREAKING OUT BY EARLY AFTERNOON. ALTHOUGH GUIDANCE IS HINTING THAT THIS WILL BE MORE PREFERRED ACROSS THE SOUTHERN CWA...WITH GUIDANCE INDICATING INSTABILITY INTO SOUTHERN WISCONSIN...HAVE INCLUDED A CHANCE FOR THUNDER IN THE GRIDS FOR THE ENTIRE CWA. ITS THESE CONVECTIVE ELEMENTS WHICH COULD SUPPLEMENT HIGHER RATES AND RESULTANT SNOWFALL TOTALS. SO FOR THE WARNING ISSUED OVERNIGHT...WILL HAVE AREA WIDE 4 TO 8 INCHES WITH THE POSSIBILITY OF SLIGHTLY HIGHER AMOUNTS NEAR 10 INCHES. IF THESE CONVECTIVE ELEMENTS WERE TO MATERIALIZE...THEN AREAS DEFINITELY COULD OBSERVE THESE HIGHER AMOUNTS. ALSO...ITS POSSIBLE THAT THESE AMOUNTS COULD BE OBSERVED IN A 4-6 HOUR WINDOW. HAVE THE WARNING ENDING EARLY THIS EVENING FOR THE WESTERN CWA AND THEN AT 3Z LATER THIS EVENING FOR THE EASTERN CWA. IF LATER GUIDANCE THIS MORNING CONTINUES TO SUPPORT CURRENT THINKING...SITUATION FORECAST TO UNFOLD LATER THIS AFTERNOON WILL DEFINITELY BE SOMETHING TO NOT TAKE LIGHTLY. RODRIGUEZ LONG TERM (TUESDAY THROUGH SUNDAY)... FAST ON THE HEELS OF TODAY`S DEPARTING SYSTEM WILL BE ANOTHER NORTHERN STREAM SYSTEM TRACKING ACROSS SOUTHERN CANADA. VERY STRONG WARM AIR ADVECTION WILL BE UNDERWAY ALOFT TUES MORNING AND EVENTUALLY DEVELOPING AT THE SURFACE AS SOUTHERLY WINDS PICK UP. DEEP AND FRESHLY RELOADED SNOW COVER OVER THE AREA WILL UNDOUBTEDLY RETARD THE WARM UP...BUT STILL THINK TEMPS SHOULD MANAGE TO CLIMB ABOVE FREEZING MOST AREAS FOR THE FIRST TIME IN WEEKS TUES AFTERNOON. WEAK COLD FRONT MOVES THROUGH TUESDAY EVENING WITH LITTLE FANFARE AND BARELY TIME FOR MUCH COLD AIR TO SEEP SOUTHWARD BEFORE WARM AIR ADVECTION BEGINS AGAIN LATER WEDNESDAY IN ADVANCE OF LATE WEDNESDAY NIGHT INTO THURSDAY`S WELL ADVERTISED BIG HULLABALOO. NOT SURPRISINGLY GIVEN THE COMPLEXITY OF THE PATTERN AND DEALING WITH PHASING ISSUES...MODELS HAVE FLOPPED BACK FROM THEIR PREVIOUS FLIP WITH MORE EMPHASIS ON A STRENGTHENING SOUTHERN LOW LIFTING NORTHEAST INTO THE GREAT LAKES. STILL SOME DIFFERENCES IN STRENGTH AND EXACT TRACK...BUT ECMWF/GFS NOW AGREE ON TAKING A SFC LOW OVER NORTHERN MISSOURI 18Z THURS NORTHEAST TO THE UPPER GREAT LAKES BY THURSDAY NIGHT...WITH CONSIDERABLE DEEPEN OF THE LOW ALONG THE WAY. ECMWF AND 06Z NAM ARE STRONGER AND A BIT FARTHER NORTHWEST...BUT NAM/GFS/ECMWF ALL HAVE THE SAME GENERAL IDEA. FIRST FORECAST ISSUE WILL BE WEDNESDAY NIGHT AS INITIAL BATCH OF WAA PRECIP BREAKS OUT AND LIFTS NORTH ACROSS THE AREA. MODEL QPF REMAINS FAIRLY HIGH AND WITH SOME ELEVATED INSTABILITY ALSO EVIDENT IN THE MODELS...CERTAINLY ENOUGH TO WARRANT A CONTINUED SLIGHT CHANCE MENTION OF THUNDERSTORMS. THE BIGGEST PROBLEM WED NIGHT WILL BE HOW FAST THE 2M TEMPS WARM UP. WHILE VERY STRONG WAA WILL BE TAKING PLACE ALOFT...INITIALLY EASTERLY WINDS OVER THE AREA AND DEEP SNOW PACK COULD ALLOW FOR A RATHER PROLONGED PERIOD OF FREEZING RAIN AND AN ICING THREAT DEPENDING ON SFC TEMPS. MANY OF THE MODEL SUGGEST A SURGE OF WARM LATE WEDNESDAY NIGHT...ESPECIALLY SOUTHERN CWA...BUT ITS GOING TO BE CLOSE. ONLY A MATTER OF A COUPLE DEGREES COULD MEAN THE DIFFERENCE BETWEEN A SIGNIFICANT ICING PROBLEM AND ALL RAIN AND THIS FAR OUT IT REALLY IS ANYONE`S GUESS WHAT SIDE OF 32F ANY ONE GIVEN AREA WILL END UP ON AS THE RAIN FALLS. CERTAINLY FARTHER NORTH WOULD STAND THE BETTER CHANCE OF FREEZING RAIN...BUT THE ICING POTENTIAL CANNOT BE RULED OUT EVEN OVER SOUTHERN PORTIONS OF THE CWA. THIS LATEST SWING IN THE MODELS TOWARD A MORE AMPLIFIED SOUTHERN LOW TRACKING NORTH IS BAD NEWS FOR IN THE HYDROLOGY DEPARTMENT. WHILE NOT AS HORRIFYING AS THE NIGHTMARE SCENARIO THE ECMWF HAD BEEN PAINTING A COUPLE DAYS AGO WITH 50 AND NEAR 60F DEWPOINTS TO THE WISCONSIN LINE...THE LATEST GUIDANCE DOES DRAG THE 40F ISODROSOTHERM FAR NORTH INTO THE AREA ON THURSDAY...WITH EVEN SOME 50F DEWPOINTS FAR SOUTHERN CWA. THE HIGHER THE DEWPOINTS THE MORE RAPID THE SNOW MELT WILL BE AND THE MORE OF A PROBLEM ANY MODERATE TO HEAVY RAIN THAT FALLS WILL POSE THURSDAY. TEMPS LOOK TO CLIMB SAFELY ABOVE FREEZING THURS AM EVEN NORTH TO THE WI BORDER ENDING THE FRZ RAIN THREAT...BUT WITH PWATS PROGGED TO CLIMB TO OVER AN INCH (200-250% OF NORMAL) THURSDAY THE POTENTIAL WILL EXIST FOR HEAVY RAINFALL. HAVE ALREADY BEEN HARPING ON ALL THE HYDRO CONCERNS IN THE ESF ISSUED FRIDAY AND UPDATED OVER THE WEEKEND AND REALLY NO BIG CHANGES IN THINKING AT THIS POINT OTHER THAN TO SAY THE FLOOD POTENTIAL IS LOOKING MORE OMINOUS THAN IT DID 24 HOURS AGO. STRONG COLD FRONT LOOKS TO SWEEP THROUGH THURSDAY EVENING BRINGING AN END TO THE RAIN AND POSSIBLE THUNDERSTORMS AND ALLOWING DRIER AND COLDER AIR TO FILTER INTO THE REGION. WHILE COLDER AIR FILTERS IN FOR THE WEEKEND WITH MEDIUM RANGE MODELS SUGGESTING ONE OR TWO SYSTEM COULD AFFECT THE REGION WITH WHAT WOULD PROBABLY BE SOME SNOWFALL. TIMING AND TRACK OF THESE LOWER AMPLITUDE WAVES ARE ALL OVER THE PLACE IN THE MODELS SO ONLY CARRYING LOW CHANCES POPS FOR NOW. IZZI && .HYDROLOGY... LATEST MODEL GUIDANCE DOES LOOK MORE WORRISOME THAN IT DID 24 HOURS AGO REGARDING THE FLOOD POTENTIAL THURSDAY...POSSIBLY LINGERING INTO THE WEEKEND. MORE DETAIL METEOROLOGICAL DISCUSSION IS ABOVE. NO CHANGES REALLY TO THE PREVIOUS HYDROLOGICAL DISCUSSION OTHER THAN SLIGHTLY MORE SNOW AND SNOW WATER EQUIVALENT IS EXPECTED TO BE IN PLACE AFTER TODAY`S SNOW SYSTEM. WILL FRESHEN UP THE ESF AGAIN THIS MORNING BUT NOT PLANNING ANY BIG CHANGES. && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * GUSTY SOUTHEASTERLY WINDS BECOMING LIGHT AND VARIABLE LATE THIS AFTERNOON/EARLY EVENING...THEN TURNING WESTERLY. * PERIODS OF HEAVY SNOW WITH NEAR WHITEOUT CONDITIONS AT TIMES WITH SNOW RATES IN EXCESS OF AN INCH PER HOUR AT TIME. * POTENTIAL FOR THUNDERSNOW. BMD //DISCUSSION...UPDATED 18Z... GOING FORECAST SEEMS LARGELY ON TRACK FOR THE TERMINALS WITH MODERATE TO HEAVY SNOW SPREADING NORTHEAST INTO THE REGION EARLY THIS AFTERNOON AND UPSTREAM OBS SHOWING VSBY QUICKLY DROPPING TO 1/4 TO 1/2 MILE. NARROW CORRIDOR ON INSTABILITY AHEAD OF AN APPROACHING F-GEN BAND CURRENTLY MOVING ACROSS THE RIVER STILL APPEARS TO BE THE BEST CHANCE FOR THUNDER TO MOVE NEAR THE TERMINALS...THOUGH STILL FAVORS AREAS JUST SOUTH OF DOWNTOWN CHICAGO. MDW MAY BE CLOSE BUT DO NOT HAVE THE CONFIDENCE IN COVERAGE TO ADD AT THIS TIME. DRIER AIR PUSHES INTO THE AREA BY LATE AFTERNOON/EARLY EVENING AND RATES SHOULD TAPER...THEN FORCING ENDS ABRUPTLY MID EVENING. LINGERING LOW LEVEL MOISTURE WILL RESULT IN LOWER MVFR OR PSBLY IFR CIGS HANGING OUT OVERNIGHT...THOUGH EXPECT VFR CONDITIONS BY AROUND DAYBREAK TOMORROW. BMD //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM CONFIDENCE IN WIND SPEEDS/DIRECTION & TIMING WIND SHIFT. * HIGH CONFIDENCE IN VSBY FALLING TO 1/4SM OR LESS WITH SNOW RATES IN EXCESS OF AN INCH PER HOUR AT TIMES...MEDIUM CONFIDENCE IN TIMING. * LOW CONFIDENCE IN THUNDERSNOW AT TERMINALS. BMD //OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z... TUESDAY NIGHT THROUGH WEDNESDAY...PREDOMINANTLY VFR. WEDNESDAY NIGHT...RAIN OR FZRA DEVELOPING. THURSDAY..RAIN/FOG/IFR LIKELY. FZRA POSSIBLE IN THE MORNING. FRIDAY...VFR PROBABLE. SATURDAY AND SUNDAY...SOME POTENTIAL FOR SNOW. IZZI && .MARINE... 324 AM CST HAVE HOISTED A GALE WARNING FOR A LARGE PORTION OF CENTRAL LAKE MICHIGAN FOR TODAY. THE DEEPER SFC LOW IN THE MODELS SHOULD RESULT IN A PERIOD OF SOUTHEAST GALES THIS MORNING INTO THE EARLY AFTERNOON BEFORE THE BAGGIER PRESSURE GRADIENT APPROACHES THE LAKE ASSOCIATED WITH THE INVERTED TROUGH NORTH OF THE LOW TRACKING ACROSS DOWNSTATE IL AND IN. BRIEF SHOT OF WESTERLY WINDS TONIGHT IN THE WAKE OF THE TROUGH AND DEPARTING LOW BEFORE SOUTHERLY WINDS BEGIN TO REALLY CRANK UP AGAIN ON TUESDAY AS ANOTHER STRONG LOW TRACK EAST ACROSS THE SOUTHERN CANADIAN PRAIRIES. COULD BE BORDERLINE SOUTHERLY GALES ON TUESDAY AFTERNOON AS WELL...BUT FOR NOW JUST STUCK WITH OCNL GALE WORDING IN THE GLF AND WILL LET NEXT SHIFT GET ANOTHER LOOK BEFORE DECIDING ON POSSIBLE GALE HEADLINES FOR TUESDAY. IZZI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011- ILZ012-ILZ019-ILZ020-ILZ021-ILZ032-ILZ039 UNTIL 6 PM MONDAY. WINTER STORM WARNING...ILZ006-ILZ013-ILZ014-ILZ022-ILZ023-ILZ033 UNTIL 9 PM MONDAY. IN...WINTER STORM WARNING...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9 PM MONDAY. LM...GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ868-LMZ870-LMZ872-LMZ874-LMZ876 UNTIL 3 PM MONDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 PM MONDAY. && $$ 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
NWS CHICAGO/ROMEOVILLE IL
1004 AM CST MON FEB 17 2014 .DISCUSSION... 330 AM CST SHORT TERM (THROUGH TONIGHT)... MAIN CONCERNS ARE WITH INCREASED POTENTIAL FOR A PERIOD OF HEAVY SNOW THIS AFTERNOON FOR THE ENTIRE CWA WHICH COULD HAVE SIGNIFICANT IMPACTS WITH WHITE OUT CONDITIONS UNDER POSSIBLE TWO TO THREE INCH PER HOUR SNOWFALL RATES SOME OF WHICH COULD FALL UNDER CONVECTIVE ELEMENTS...WITH AREA WIDE 4 TO 8 INCHES LIKELY AND SOME ISOLATED AMOUNTS NEAR 10 INCHES DEFINITELY NOT OUT OF THE QUESTION. IMPRESSIVE STRONG STORM ANTICIPATED TO TAKE SHAPE OVER THE AREA LATER TODAY CAN BE OBSERVED ON SATELLITE IMAGERY...WITH MID/UPPER LEVEL TROUGH CURRENTLY PUSHING EAST THROUGH THE NORTHERN PLAINS. OUT AHEAD OF THIS SYSTEM...LATEST RAP ANALYSIS DEPICTING STRONG ISENTROPIC ASCENT OCCURRING ACROSS THE ENTIRE REGION INCLUDING LOCALLY OVER THE CWA. THIS HAS RESULTED IN PERSISTENT MID/HIGH LEVEL CLOUD COVER TO STREAM OUT AHEAD OF THIS SYSTEM...WITH CURRENT RADAR IMAGERY LIGHTING UP WITH SOME DECENT RETURNS. ALTHOUGH RATHER DRY AIR IN PLACE HAS LIMITED ANY PRECIP TO REACH THE SURFACE AND ANTICIPATE FOR THIS TO FURTHER BE THE CASE OVER THE NEXT COUPLE OF HOURS. WHAT COULD BE EXPECTED IN THE NEAR TERM ARE SOME ISOLATED FLURRIES PRIMARILY OVER THE NORTHWEST HALF OF THE CWA...WITH RFD CURRENTLY REPORTING 9 MILES IN LIGHT SNOW. ISENTROPIC ASCENT WILL CONTINUE THIS MORNING...WITH SHORT TERM GUIDANCE HINTING AT THE POSSIBILITY FOR FURTHER PRECIP DEVELOPMENT ENTERING THE SOUTHWEST CWA JUST AFTER THE 12Z TIME FRAME. PREVIOUSLY DISCUSSED WARMING/WARM WEDGE STILL ANTICIPATED HERE THIS MORNING AND COULD INITIALLY BRING A WINTRY MIX BUT STAYING CONFINED TO THE SOUTHERN HALF OF THE CWA...PRIMARILY SOUTH OF THE I80 CORRIDOR. IF ANYTHING WERE TO OCCUR DURING THIS TIME FRAME...ANTICIPATE IT TO BE ON THE LIGHTER SIDE WITH THE PREVIOUSLY MENTIONED DRIER AIR STILL NEEDING TO BE OVERCOME. NONETHELESS...WITH AN ANTICIPATED SLOWING TREND WITH THE EVOLUTION OF TODAY`S SYSTEM...THIS WINTRY MIX COULD BE MORE PREVALENT THAN PREVIOUSLY THOUGHT TO START THE PERIOD. SO HAVE INCLUDED CHANCE ZR/IP IN THE GRIDS THROUGH 15Z. CAN MAKE OUT TWO SEPARATE PIECES OF STRONG ENERGY TRAVERSING THE MID LEVEL FLOW...NOW WITH ALL GUIDANCE IN STRONG AGREEMENT WITH THE EVOLUTION OF THIS ENERGY AS IT APPROACHES THE REGION. ABOUT THE ONLY DIFFERENCE AT THIS TIME IS SOME SLIGHT TIMING DIFFERENCES WITH THE APPROACH OF THE BETTER FORCING/PRECIP LATER TODAY. A CONTINUED SLOWER TREND HAS BEEN THE PREFERRED TREND HERE THIS MORNING...AND HAVE DELAYED HIGHEST POPS TODAY. ALTHOUGH DID NOT OVERLY STRAY TOO MUCH WITH THE PREVIOUSLY MENTIONED ISENTROPIC ASCENT AND POTENTIAL PRECIP OUT AHEAD OF IT. HAVE CONTINUED THE MENTION IN THE GRIDS FOR A MIX OF SLEET FOR LATER IN THE MORNING...MAINLY FOR THE SOUTHERN TIER OF COUNTIES. ALTHOUGH THERMAL PROFILES WOULD BE SUPPORTIVE OF THIS WINTRY MIX CONTINUING...HAVE LIMITED MENTION OF THIS MIX AS BETTER FORCING SHOULD BE ARRIVING DURING THIS TIME. WHATEVER LINGERING WARM WEDGE IN THE COLUMN WILL QUICKLY COOL THE COLUMN TO THE WET BULB AS STRONG DYNAMIC FORCING ARRIVES...WITH ANY MIX QUICKLY CHANGING OVER TO ALL SNOW. ONCE AGAIN...ALL GUIDANCE POINTING AT SIGNIFICANT SNOWFALL RATES BEGINNING AT SOON AS LATE MORNING FOR THE WESTERN CWA. TWO PIECES OF ENERGY WILL PHASE TOGETHER BY EARLY AFTERNOON...WITH THIS MID/UPPER LEVEL TROUGH BECOMING NEGATIVELY TILTED. AS THIS OCCURS...ATTENDANT LOW TO DEEPEN AS IT MOVES THROUGH CENTRAL ILLINOIS WITH 850MB LOW REALLY BEGINNING TO TAKE SHAPE. STRONG DYNAMICAL FORCING ASSOCIATED WITH THIS MID LEVEL TROUGH AND SIGNIFICANT HEIGHT FALLS WILL ALLOW FORCING TO SWING THROUGH THE CWA BY LATE MORNING INTO THE EARLY AFTERNOON. ASSOCIATED FRONTOGENETICAL FORCING WILL LIKEWISE PUSH EAST THROUGH THE AREA THIS AFTERNOON...WITH THE PRESENCE OF NEGATIVE EPV. THIS PRESENCE OF BOTH SLANTWISE AND UPRIGHT MOTIONS ARE LEADING FOR SOME REALLY IMPRESSIVE VERTICAL MOTION...WITH FORECAST OMEGA AMONG ALL GUIDANCE SOME OF THE HIGHEST IVE OBSERVED IN SOME TIME. THE STRONGEST VERTICAL MOTIONS ARE EXPECTED TO PUSH EAST TO WEST ACROSS THE CWA INTO THE EARLY AFTERNOON TIME FRAME AND CONTINUING THROUGH MID/LATE AFTERNOON...WITH FORCING CENTERED RIGHT IN THE MIDDLE OF THE CWA. ALTHOUGH CURRENT FORECAST SNOW TOTALS ARE THE HIGHEST IN THESE LOCATIONS...TOTALS DONT STRAY TOO MUCH FROM THE AMOUNTS ACROSS THE REMAINING CWA. THIS IS IN DUE TO PART TO HOW UNSTABLE THIS SYSTEM WILL BE...INCLUDING CONVECTIVE INSTABILITY. BOTH NAM/GFS SHOWING IMPRESSIVE MUCAPE TO PUSH NORTHEAST THROUGH THE CWA AS EARLY AS MID MORNING...AND THE BEGINNING STAGES OF THIS CAN ALREADY BE OBSERVED TO OUR WEST/SOUTHWEST WITH LATEST RAP ANALYSIS DEPICTING 100-200 J/KG OVER IOWA/MISSOURI/KANSAS. WITH SREF GUIDANCE INDICATING HIGH PROBABILITIES OF AT LEAST 50-100 J/KG OF MUCAPE TO MOVE OVERHEAD LATER TODAY...FEEL THAT THE NAM/GFS SOLUTION OF 100 TO ALMOST 300 J/KG IS NOT OF THE QUESTION. THE PRESENCE OF THIS STRONG FORCING...STRONG INSTABILITY AND ABUNDANCE OF MOISTURE NOT ONLY LIKELY BEING PRESENT BUT ALSO COMING TOGETHER...HAS STEERED THE FORECAST SIGNIFICANTLY MORE PESSIMISTIC THIS MORNING. HEAVIEST SNOW...WHICH WILL FALL WITH HIGH INTENSITIES AND POSSIBLY AT A RATE OF TWO TO THREE INCHES PER HOUR AT TIMES SHOULD ARRIVE THE FAR WESTERN CWA BY MID/LATE MORNING...AND THEN SPREADING EAST THROUGH THE REMAINING CWA BY EARLY AFTERNOON. EXPECT THESE HIGH SNOWFALL INTENSITIES THROUGH MID TO LATE AFTERNOON...AND POSSIBLY CONTINUE INTO THE EARLY EVENING FOR THE EASTERN THIRD OF THE CWA. THIS HEAVY SNOW WILL QUICKLY ACCUMULATE ON ROADS WITH NEAR VISIBILITY LIKELY UNDER THIS HEAVY SNOW...CREATING VERY HAZARDOUS CONDITIONS. AS WAS MENTIONED PREVIOUSLY...THE HIGHEST TOTALS ARE IN THE CWA ALIGNED WITH THE BETTER FORCING...BUT FEEL THAT ANY LACKING FORCING WILL BE SUPPLEMENTED WITH THE CONVECTIVE NATURE OF THIS SYSTEM. CONVECTIVE ALLOWING MODELS INDICATE THE PRESENCE OF THUNDER BREAKING OUT BY EARLY AFTERNOON. ALTHOUGH GUIDANCE IS HINTING THAT THIS WILL BE MORE PREFERRED ACROSS THE SOUTHERN CWA...WITH GUIDANCE INDICATING INSTABILITY INTO SOUTHERN WISCONSIN...HAVE INCLUDED A CHANCE FOR THUNDER IN THE GRIDS FOR THE ENTIRE CWA. ITS THESE CONVECTIVE ELEMENTS WHICH COULD SUPPLEMENT HIGHER RATES AND RESULTANT SNOWFALL TOTALS. SO FOR THE WARNING ISSUED OVERNIGHT...WILL HAVE AREA WIDE 4 TO 8 INCHES WITH THE POSSIBILITY OF SLIGHTLY HIGHER AMOUNTS NEAR 10 INCHES. IF THESE CONVECTIVE ELEMENTS WERE TO MATERIALIZE...THEN AREAS DEFINITELY COULD OBSERVE THESE HIGHER AMOUNTS. ALSO...ITS POSSIBLE THAT THESE AMOUNTS COULD BE OBSERVED IN A 4-6 HOUR WINDOW. HAVE THE WARNING ENDING EARLY THIS EVENING FOR THE WESTERN CWA AND THEN AT 3Z LATER THIS EVENING FOR THE EASTERN CWA. IF LATER GUIDANCE THIS MORNING CONTINUES TO SUPPORT CURRENT THINKING...SITUATION FORECAST TO UNFOLD LATER THIS AFTERNOON WILL DEFINITELY BE SOMETHING TO NOT TAKE LIGHTLY. RODRIGUEZ LONG TERM (TUESDAY THROUGH SUNDAY)... FAST ON THE HEELS OF TODAY`S DEPARTING SYSTEM WILL BE ANOTHER NORTHERN STREAM SYSTEM TRACKING ACROSS SOUTHERN CANADA. VERY STRONG WARM AIR ADVECTION WILL BE UNDERWAY ALOFT TUES MORNING AND EVENTUALLY DEVELOPING AT THE SURFACE AS SOUTHERLY WINDS PICK UP. DEEP AND FRESHLY RELOADED SNOW COVER OVER THE AREA WILL UNDOUBTEDLY RETARD THE WARM UP...BUT STILL THINK TEMPS SHOULD MANAGE TO CLIMB ABOVE FREEZING MOST AREAS FOR THE FIRST TIME IN WEEKS TUES AFTERNOON. WEAK COLD FRONT MOVES THROUGH TUESDAY EVENING WITH LITTLE FANFARE AND BARELY TIME FOR MUCH COLD AIR TO SEEP SOUTHWARD BEFORE WARM AIR ADVECTION BEGINS AGAIN LATER WEDNESDAY IN ADVANCE OF LATE WEDNESDAY NIGHT INTO THURSDAY`S WELL ADVERTISED BIG HULLABALOO. NOT SURPRISINGLY GIVEN THE COMPLEXITY OF THE PATTERN AND DEALING WITH PHASING ISSUES...MODELS HAVE FLOPPED BACK FROM THEIR PREVIOUS FLIP WITH MORE EMPHASIS ON A STRENGTHENING SOUTHERN LOW LIFTING NORTHEAST INTO THE GREAT LAKES. STILL SOME DIFFERENCES IN STRENGTH AND EXACT TRACK...BUT ECMWF/GFS NOW AGREE ON TAKING A SFC LOW OVER NORTHERN MISSOURI 18Z THURS NORTHEAST TO THE UPPER GREAT LAKES BY THURSDAY NIGHT...WITH CONSIDERABLE DEEPEN OF THE LOW ALONG THE WAY. ECMWF AND 06Z NAM ARE STRONGER AND A BIT FARTHER NORTHWEST...BUT NAM/GFS/ECMWF ALL HAVE THE SAME GENERAL IDEA. FIRST FORECAST ISSUE WILL BE WEDNESDAY NIGHT AS INITIAL BATCH OF WAA PRECIP BREAKS OUT AND LIFTS NORTH ACROSS THE AREA. MODEL QPF REMAINS FAIRLY HIGH AND WITH SOME ELEVATED INSTABILITY ALSO EVIDENT IN THE MODELS...CERTAINLY ENOUGH TO WARRANT A CONTINUED SLIGHT CHANCE MENTION OF THUNDERSTORMS. THE BIGGEST PROBLEM WED NIGHT WILL BE HOW FAST THE 2M TEMPS WARM UP. WHILE VERY STRONG WAA WILL BE TAKING PLACE ALOFT...INITIALLY EASTERLY WINDS OVER THE AREA AND DEEP SNOW PACK COULD ALLOW FOR A RATHER PROLONGED PERIOD OF FREEZING RAIN AND AN ICING THREAT DEPENDING ON SFC TEMPS. MANY OF THE MODEL SUGGEST A SURGE OF WARM LATE WEDNESDAY NIGHT...ESPECIALLY SOUTHERN CWA...BUT ITS GOING TO BE CLOSE. ONLY A MATTER OF A COUPLE DEGREES COULD MEAN THE DIFFERENCE BETWEEN A SIGNIFICANT ICING PROBLEM AND ALL RAIN AND THIS FAR OUT IT REALLY IS ANYONE`S GUESS WHAT SIDE OF 32F ANY ONE GIVEN AREA WILL END UP ON AS THE RAIN FALLS. CERTAINLY FARTHER NORTH WOULD STAND THE BETTER CHANCE OF FREEZING RAIN...BUT THE ICING POTENTIAL CANNOT BE RULED OUT EVEN OVER SOUTHERN PORTIONS OF THE CWA. THIS LATEST SWING IN THE MODELS TOWARD A MORE AMPLIFIED SOUTHERN LOW TRACKING NORTH IS BAD NEWS FOR IN THE HYDROLOGY DEPARTMENT. WHILE NOT AS HORRIFYING AS THE NIGHTMARE SCENARIO THE ECMWF HAD BEEN PAINTING A COUPLE DAYS AGO WITH 50 AND NEAR 60F DEWPOINTS TO THE WISCONSIN LINE...THE LATEST GUIDANCE DOES DRAG THE 40F ISODROSOTHERM FAR NORTH INTO THE AREA ON THURSDAY...WITH EVEN SOME 50F DEWPOINTS FAR SOUTHERN CWA. THE HIGHER THE DEWPOINTS THE MORE RAPID THE SNOW MELT WILL BE AND THE MORE OF A PROBLEM ANY MODERATE TO HEAVY RAIN THAT FALLS WILL POSE THURSDAY. TEMPS LOOK TO CLIMB SAFELY ABOVE FREEZING THURS AM EVEN NORTH TO THE WI BORDER ENDING THE FRZ RAIN THREAT...BUT WITH PWATS PROGGED TO CLIMB TO OVER AN INCH (200-250% OF NORMAL) THURSDAY THE POTENTIAL WILL EXIST FOR HEAVY RAINFALL. HAVE ALREADY BEEN HARPING ON ALL THE HYDRO CONCERNS IN THE ESF ISSUED FRIDAY AND UPDATED OVER THE WEEKEND AND REALLY NO BIG CHANGES IN THINKING AT THIS POINT OTHER THAN TO SAY THE FLOOD POTENTIAL IS LOOKING MORE OMINOUS THAN IT DID 24 HOURS AGO. STRONG COLD FRONT LOOKS TO SWEEP THROUGH THURSDAY EVENING BRINGING AN END TO THE RAIN AND POSSIBLE THUNDERSTORMS AND ALLOWING DRIER AND COLDER AIR TO FILTER INTO THE REGION. WHILE COLDER AIR FILTERS IN FOR THE WEEKEND WITH MEDIUM RANGE MODELS SUGGESTING ONE OR TWO SYSTEM COULD AFFECT THE REGION WITH WHAT WOULD PROBABLY BE SOME SNOWFALL. TIMING AND TRACK OF THESE LOWER AMPLITUDE WAVES ARE ALL OVER THE PLACE IN THE MODELS SO ONLY CARRYING LOW CHANCES POPS FOR NOW. IZZI && .HYDROLOGY... LATEST MODEL GUIDANCE DOES LOOK MORE WORRISOME THAN IT DID 24 HOURS AGO REGARDING THE FLOOD POTENTIAL THURSDAY...POSSIBLY LINGERING INTO THE WEEKEND. MORE DETAIL METEOROLOGICAL DISCUSSION IS ABOVE. NO CHANGES REALLY TO THE PREVIOUS HYDROLOGICAL DISCUSSION OTHER THAN SLIGHTLY MORE SNOW AND SNOW WATER EQUIVALENT IS EXPECTED TO BE IN PLACE AFTER TODAY`S SNOW SYSTEM. WILL FRESHEN UP THE ESF AGAIN THIS MORNING BUT NOT PLANNING ANY BIG CHANGES. && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * HEAVY SNOW TO DEVELOP EARLY-MID AFTERNOON WITH OCNL VSBY BETWEEN 1/16SM AND 1/4SM EXPECTED * SLIGHT CHANCE OF THUNDERSTORM (THUNDERSNOW) IN THE MID-LATE AFTERNOON * STRONG SOUTHEAST WINDS WITH GUSTS TO AROUND 25KT EXPECTED. * QUICK IMPROVEMENT TO CIGS/VSBY AS SNOW ENDS EARLY THIS EVENING IZZI/BMD //DISCUSSION...UPDATED 12Z... A SHORT LIVED BUT INTENSE SNOW STORM WILL AFFECT THE AREA TODAY. RADAR ECHOS OVER DOWNSTATE ILLINOIS ARE INITIALLY EVAPORATING BEFORE REACHING THE GROUND...BUT SNOW COULD BEGIN TO PENETRATE THE LOW LEVEL DRY AIR AS EARLY AS MID MORNING...BUT MORE LIKELY BY LATE MORNING AND DEFINITELY BY EARLY AFTERNOON. MOST INTENSE SNOWFALL STILL LOOKS TO BE FOCUSED ON THE 19-23Z TIME FRAME FOR CHICAGO AND ALL INDICATIONS ARE THAT VSBY WILL DROP AT TIMES TO AT LEAST 1/4SM IF NOT LOWER WITH EVEN SOME THREAT OF +TSSN. SNOWFALL RATES COULD EXCEED 2 INCHES PER HOUR AT TIMES. STRONG SOUTHEAST WINDS THIS MORNING WILL DECREASE IN INTENSITY SOME AS THE SNOW PEAKS THIS AFTERNOON...BUT DIRECTION LIKELY TO REMAIN SE THROUGH MOST IF NOT ALL OF THE DURATION OF THE ACCUMULATING SNOW. INVERTED TROUGH SHOULD MOVE THROUGH THIS EVENING RESULTING IN WIND SHIFT TO WEST AND A QUICK WINDING DOWN OF THE SNOWFALL. IZZI //ORD AND MDW CONFIDENCE...UPDATED 16Z... * HIGH CONFIDENCE IN ONSET TIME OF MOD-HVY SNOW +/- AN HOUR OR SO * MEDIUM CONFIDENCE IN OCNL VSBY 1/4SM OR LOWER WITH ACCUMULATION RATES OF 1"/HOUR OR GREATER * MEDIUM-HIGH CONFIDENCE ON END TIME OF SNOW MONDAY EVENING +/- AN HOUR OR SO * HIGH CONFIDENCE IN REMAINDER OF FORECAST ELEMENTS IZZI/BMD //OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z... TUESDAY NIGHT THROUGH WEDNESDAY...PREDOMINANTLY VFR. WEDNESDAY NIGHT...RAIN OR FZRA DEVELOPING. THURSDAY..RAIN/FOG/IFR LIKELY. FZRA POSSIBLE IN THE MORNING. FRIDAY...VFR PROBABLE. SATURDAY AND SUNDAY...SOME POTENTIAL FOR SNOW. IZZI && .MARINE... 324 AM CST HAVE HOISTED A GALE WARNING FOR A LARGE PORTION OF CENTRAL LAKE MICHIGAN FOR TODAY. THE DEEPER SFC LOW IN THE MODELS SHOULD RESULT IN A PERIOD OF SOUTHEAST GALES THIS MORNING INTO THE EARLY AFTERNOON BEFORE THE BAGGIER PRESSURE GRADIENT APPROACHES THE LAKE ASSOCIATED WITH THE INVERTED TROUGH NORTH OF THE LOW TRACKING ACROSS DOWNSTATE IL AND IN. BRIEF SHOT OF WESTERLY WINDS TONIGHT IN THE WAKE OF THE TROUGH AND DEPARTING LOW BEFORE SOUTHERLY WINDS BEGIN TO REALLY CRANK UP AGAIN ON TUESDAY AS ANOTHER STRONG LOW TRACK EAST ACROSS THE SOUTHERN CANADIAN PRAIRIES. COULD BE BORDERLINE SOUTHERLY GALES ON TUESDAY AFTERNOON AS WELL...BUT FOR NOW JUST STUCK WITH OCNL GALE WORDING IN THE GLF AND WILL LET NEXT SHIFT GET ANOTHER LOOK BEFORE DECIDING ON POSSIBLE GALE HEADLINES FOR TUESDAY. IZZI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011- ILZ012-ILZ019-ILZ020-ILZ021-ILZ032-ILZ039 UNTIL 6 PM MONDAY. WINTER STORM WARNING...ILZ006-ILZ013-ILZ014-ILZ022-ILZ023-ILZ033 UNTIL 9 PM MONDAY. IN...WINTER STORM WARNING...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9 PM MONDAY. LM...GALE WARNING...LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ868-LMZ870-LMZ872-LMZ874-LMZ876 UNTIL 3 PM MONDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 3 PM MONDAY. && $$ 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
NWS NORTHERN INDIANA
352 PM EST MON FEB 17 2014 .SYNOPSIS... ISSUED AT 115 PM EST MON FEB 17 2014 A LOW PRESSURE SYSTEM OVER CENTRAL ILLINOIS WILL QUICKLY MOVE INTO WESTERN LAKE ERIE THIS EVENING AND DEEPLY STRENGTHEN. THIS WILL CAUSE A BAND OF MODERATE TO HEAVY SNOW TO PIVOT THROUGH THE AREA THROUGH THE EVENING HOURS. SOME SLEET AND FREEZING RAIN WILL MIX WITH THE SNOW ALONG AND SOUTH OF HIGHWAY 24 IN INDIANA AND OHIO. TOTAL SNOW ACCUMULATIONS ARE FORECAST TO RANGE BETWEEN 2 AND 6 INCHES ACROSS THE FORECAST AREA...HEAVIEST ACROSS NORTHERN AREAS. TRAVEL CONDITIONS WILL RAPIDLY DETERIORATE THROUGH THE AFTERNOON AND EVENING HOURS. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 349 PM EST MON FEB 17 2014 SNOWFALL RATES 2-3.5 INCHES/HR IN XTRMLY HVY TSSN ENTERING WRN CWA. CONTD VERY SIMILAR RAP/NAM/PREV BLENDED APPROACH UTILIZED WITH MIDDAY UPDATE. GENERAL CONTD CONSENSUS OF SREF MEAN AND TIGHT PLUME PACK IN ADDITION TO 12 UTC NAM COBB OUTPUT SUPPORTS LATEST EVENT TOTALS IN PRIOR 1233 PM EST WSW UPDATE WITH HIEST GENRLY ALONG NORTH OF TOLL ROAD. THANKFULLY XTRM RATES BRIEF AND WITH TRANSITION TO LESS THAN OPTIMAL FLAKE SIZE OUTSIDE OF CONVECTIVE ELEMENTS SHOULD KEEP MAJORITY OF ACCUMS TO LTE 6 INCHES. SOME CONCERN THOUGH FOR HIR AMOUNTS WITH TROWAL LIFTING ACRS FAR NRN CWA THIS EVENING PRIOR TO LIFTG FARTHER N OF CWA BYND 03 UTC...INDICATIONS THOUGH THAT IT WILL LIE OUT E-W JUST NORTH OF CWA...BEFORE GRDL EWD LIFTOUT. LEADING WARM CONVEYOR BELT INTENSE WITH XTRM MSTR TAP WITH 6-7 G/KG ON I295K SFC SLIDES EWD THROUGH SRN IN THIS EVENING...PROVIDING XTRM MFLUX/UVM ATOP NOSE OF RAMPING SWRLY 850-7H JET AXIS. JETLET OF 65 KTS AT 21 UTC POSITIONED ACRS SRN IN...STRENGTHENS TO 75 KTS MEAN LYR FLOW INTO SRN OH BY 00 UTC. SPECIAL KILX MIDDAY SNDG YIELDS 320 J/KG MUCAPE/LIFTED FM 7H AND WHILE LATEST RAP TREND NOTED DOWNWARD WRT MUCAPE WL CONT WITH PRIOR AREA ADDED AND HAVE NOW INCLUDED FAR ERN AREAS AS WELL IN 22-02 UTC TIMEFRAME GIVEN APPROACH OF STOUT 6-7 C/KM MID TROPOSPHERIC LAPSE RATE PLUME AND SYSTEM DEEPENING. MID LVL CIRC AND TO CLOSE OFF ACRS CHICAGOLAND SHORTLY AND TRACK EWD TO WINDSOR ONT BY 09 UTC TUE...ALSO SUGGESTING HIEST AMOUNTS HERE/JUST NORTH OF CWA...WHERE HIGHLY ELEVATED MAX UVM BEST COLLOCATED WITHIN A SATURATED DGZ. RAPID CRASH OF CLOUD DEPTH IN WAKE OF SYSTEM IN PERTURBED MOIST BLYR STILL SUGGESTIVE OF BRIEF LIGHT FZDZSN POTNL AT BEFORE ENDING. HELD ONTO CLOUD COVER A BIT LONGER INTO TUE AWAITING SHORTWAVE 925MB RIDGING THAT STILL HOLDS JUST WEST FM KGRB INTO NERN IL AT 12 UTC TUE. && .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 349 PM EST MON FEB 17 2014 FOCUS CONTINUES ON WARMER TEMPERATURES/ADDITIONAL PRECIPITATION THROUGH FRIDAY AND FLOODING/SEVERE WEATHER CONCERNS. THE NEXT RIPPLE IN THE UPPER FLOW WILL AID IN THE DEVELOPMENT OF LOW PRESSURE WHICH WILL TRACK ACROSS SOUTHERN CANADA WITH A TRAILING COLD FRONT. THIS FRONT WILL SWEEP INTO THE REGION LATE TUES NGT INTO WEDNESDAY BUT WILL BE STARVED OF MOISTURE AND DYNAMICS LEADING TO A GENERALLY QUIET PASSAGE. ALTHOUGH COOLER AIR WILL ARRIVE BEHIND THE FRONT...THIS WILL BE SHORT LIVED AND COMPARED TO THE AIR OF THE PAST SEVERAL WEEKS WILL FEEL DOWNRIGHT NICE. TEMPERATURES WILL CLIMB ABOVE FREEZING WEDNESDAY ALLOWING FOR THE START OF THE MELTDOWN OF THE LARGE SNOWPACK ACROSS THE REGION. DEWPOINTS WILL REMAIN IN THE 20S...KEEPING ANY FOG FORMATION AWAY AND ALLOWING FOR A SLOW RELEASE AND NO SIGNIFICANT HYDRO ISSUES. PIECE OF ENERGY ORIGINATING FROM GULF OF ALASKA UPPER LOW WILL DROP INTO THE WESTERN STATES AND CARVE OUT A DEEPENING TROUGH WHICH WILL ALLOW A SURGE OF EVEN WARMER AIR STARTING LATE WEDS NGT INTO THURS GULF OF MEXICO OPENING WIDE TO SEND ABUNDANT MSTR TO THE REGION. THIS WILL SET THE STAGE FOR PRECIP ARRIVING LATE WEDS NGT INTO THURSDAY MORNING. LOW LEVEL THERMAL PROFILES SHOW ABOVE FREEZING VALUES...HOWEVER REMAINING SNOWPACK MAY POSE A INITIAL CHALLENGE AND THREAT OF BRIEF PERIOD OF FREEZING RAIN AT ONSET OF RAINFALL. HOWEVER...BY MID THURSDAY MORNING TEMPS SHOULD BE ABOVE FREEZING AND ANY ICING THREAT OVER. HAVE ADJUSTED GRIDS TO REFLECT THIS. IN ADDITION...LAST FEW FRAMES OF NAM12 AND HINTS ON ECMWF/GFS INDICATE NEGATIVE SHOWWALTER VALUES BEGIN TO NUDGE IN BY LATE MORNING IN WESTERN AREAS AND ACROSS THE ENTIRE AREA THURS AFTERNOON. ECMWF IS MOST AGGRESSIVE WITH MSTR RETURN AS SFC DEWPTS CLIMB INTO THE LOWER 50S IN SE HALF. WHILE SOME MODELS HINT THERE COULD BE A BREAK IN PRECIP...HAVE DECIDED TO CONTINUE WITH CAT POPS...INTRODUCED THUNDER WEST LATE AM AND INCREASED TO CHC THUNDER ALL AREAS THURS AFTN. CONTINUED MENTION OF FOG WHICH WILL LIKELY BE DENSE AS DWPTS CLIMB ABOVE 40S ACROSS THE ENTIRE AREA. BEST CHANCES FOR HEAVY RAINFALL LOOK TO BE THROUGH THURS MORNING AND AGAIN LATE AFTN INTO EVENING AS COLD FRONT ARRIVES. IN TERMS OF FLOODING THREAT...GREATEST RELEASE WILL OCCUR INTO THURS EVE AND ONLY SLOW DOWN SOMEWHAT THURS NGT WITH TEMPS CLIMBING BACK ABOVE FREEZING FRIDAY. IF ADVERTISED DEWPOINTS DO ARRIVE...LIKELY WON`T BE MUCH OF A SNOWPACK LEFT WITH FLOODING CONCERNS INCREASE SUBSTANTIALLY AND TEMPS IN THE 30S TO LOW 40S WILL ALLOW FOR CONTINUED MELTING. HWO AND ESF HAVE THIS HANDLED WELL THUS FAR SO NO CHANGES PLANNED. TO COMPLICATE MATTERS FURTHER...GIVEN THE AMOUNT OF MSTR...ELEVATED INSTABILITY AND STRONG LL FLOW ON THE ORDER OF 60 KTS PLUS...THREAT FOR STG-SVR STORMS DOES EXIST AND WILL NEED TO BE MONITORED. SPC PLACED IN/OH UNDER DAY 4 OUTLOOK FOR SEVERE ON MORNING ISSUANCE. WILL HOLD OFF FOR NOW ON MENTION IN HWO. SEVERAL CLIPPER SYSTEMS TO MOVE THROUGH OVER THE WEEKEND TO WRECK HAVOC WITH TEMPS AS AFTERNOON HIGHS EVEN INTO SAT REMAIN NEAR OR ABOVE FREEZING. MORE SIGNIFICANT BLAST OF COLD AIR WILL ARRIVE LATE IN THE WEEKEND INTO NEXT WEEK AS 850 MB TEMPS DROP BACK TO -10 C OR LOWER. CHANCE FOR PRECIP MAY ARRIVE WITH EACH CLIPPER SYSTEM BUT KEEPING WITH GOING FORECAST WITH MINIMAL CHANCES FOR NOW AS TIMING/TRACK ISSUES ABOUND. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1250 PM EST MON FEB 17 2014 FOCUS PRIMARILY UPON UPSTREAM/RAPIDLY DEEPENING SYSTEM ACRS CNTL IL TO TRACK INTO WRN LK ERIE BY LATE THIS EVENING. ELEVATED CONVECTIVE POTNL NECESSITATES INCLUSION OF TSSN AT KSBN...CHCS TS PSBL AT KFWA...BUT WILL HOLD FOR NOW. STILL SNOWFALL RATES 1 TO 2 INCHES PER HOUR TO BRING PERIOD OF IFR/LIFR MET CONDS ACRS NRN IN. PTYPE SHOULD REMAIN ALL SNOW AT KSBN...THOUGH FAR NRN REACH OF WARM LYR ALOFT MAY CREATE SOME MIXED SNPL AT KFWA PRIOR TO CHANGEOVER TO ALL SNOW WITH STRONG DYNAMIC COLUMN COOLING. CLOUD TOPS RAPIDLY LWR/WARM AS SYSTEM DEPARTS LATE THIS EVENING GIVING POTNL FOR SUPERCOOLED FZDZ MIX WITH LIGHT SN. KEPT AOB FUEL ATL INTO AT LEAST 14 UTC TUE PER STRENGTH OF INVERSION...LONGER THAN LATEST MODEL GUID/PRIOR FCSTS WOULD SUGGEST. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER WEATHER ADVISORY UNTIL 3 AM EST TUESDAY FOR INZ006>009- 017-018-025>027-032>034. WINTER WEATHER ADVISORY UNTIL 11 PM EST /10 PM CST/ THIS EVENING FOR INZ003>005-012>016-020-022>024. MI...WINTER WEATHER ADVISORY UNTIL 3 AM EST TUESDAY FOR MIZ079>081. WINTER WEATHER ADVISORY UNTIL 11 PM EST THIS EVENING FOR MIZ077- 078. OH...WINTER WEATHER ADVISORY UNTIL 3 AM EST TUESDAY FOR OHZ001-002- 004-005-015-016-024-025. LM...NONE. && $$ SYNOPSIS...MURPHY SHORT TERM...MURPHY LONG TERM...FISHER AVIATION...MURPHY VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
116 PM EST MON FEB 17 2014 .SYNOPSIS... ISSUED AT 115 PM EST MON FEB 17 2014 A LOW PRESSURE SYSTEM OVER CENTRAL ILLINOIS WILL QUICKLY MOVE INTO WESTERN LAKE ERIE THIS EVENING AND DEEPLY STRENGTHEN. THIS WILL CAUSE A BAND OF MODERATE TO HEAVY SNOW TO PIVOT THROUGH THE AREA THROUGH THE EVENING HOURS. SOME SLEET AND FREEZING RAIN MAY MIX WITH THE SNOW ALONG AND SOUTH OF HIGHWAY 24 IN INDIANA AND OHIO. TOTAL SNOW ACCUMULATIONS ARE FORECAST TO RANGE BETWEEN 2 AND 6 INCHES ACROSS THE FORECAST AREA...HEAVIEST ACROSS NORTHERN AREAS. TRAVEL CONDITIONS WILL RAPIDLY DETERIORATE THROUGH THE AFTERNOON AND EVENING HOURS. && .UPDATE... ISSUED AT 1250 PM EST MON FEB 17 2014 DECISIVELY STRONG UPSTREAM MUCAPE PLUME 150-400 J/KG PER LATEST RAP ANALYSIS ASSOCD WITH EXTREME LAPSE RATES AOA 700 MB. GIVEN STRENGTH OF FORCED ASCENT OF 60 PLUS KNOT 8H JET AS IT MOVES EWD ACRS SRN IN...THEN MORE NEWD INTO WCNTL OH THIS EVENING AS SYSTEM UNDERGOES RAPID DEEPENING PER HFC BURGEONING TO 230-250M/12 HR AS IT SLIDES EWD THRU CWA. INSTABILITY/DEEPENING AND POIGNANT DRY SLOT PUNCH INTO SRN IL SUGGEST INTRODUCTION OF ISOLD TS IN HEAVY SN APPLICAPLE FOR LATER THIS AFTN. PTYPE REMAINS A CONCERN...THOUGH BY AND LARGE DYNAMIC/INITIAL EVAP COOLING SHOULD PRECLUDE SIG NWD PENETRATION INTO SRN REACH OF CWA...SIMILAR TO LATEST RAP13 MAX TW PROGS. BRIEF ZR PSBL HERE THOUGH SLEETY/GRAUPEL MIX MORE DOMINANT...STILL KEEPING SLR IN CHECK. FARTHER NORTH CONVECTIVE ELEMENTS TO SUPPORT BRIEF SNFL RATES NEAR 2 IN/HR. FURTHERMORE...CLOSE OFF OF MID TROPOSPHERIC FLOW ACRS SRN MI AS IT GENUFLECTS TO NEG TILT WITH WWD BEND TO MOIST I295K TROWAL LIFTING NWD ACRS TOLL ROAD INTO SRN LWR MI...TO LIKELY BRING HIEST AMOUNTS ACRS NWRN IN INTO SCNTL LWR MI...WHERE ISOLD GTE 6 INCHES PSBL. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 343 AM EST MON FEB 17 2014 BURST OF MOD-HVY SNOW LATER THIS AFTN AND EVE / MIXED WITH SLEET SOUTH OF HWY 24 / THE PRIMARY FOCUS THIS PERIOD... MORNING WATER VAPOR IMAGERY SHOWS A WELL DEFINED PV ANOMALY NEAR THE NE/CO BORDER WITH ANOTHER NORTHERN STREAM UPPER WAVE EDGING TOWARD THE MT/ND BORDER. GUIDANCE NOW IN EXCELLENT AGREEMENT IN PHASING THESE WAVES AS THEY RIPPLE QUICKLY EAST WITH A CLOSED MID LVL CIRCULATION EVENTUALLY EMERGING OVER SOUTHERN LOWER MICHIGAN THIS EVENING. THIS STRONG UPPER TROUGH WILL SHIFT NEGATIVE AND DEEP WITH 1.5 PVU SFC NEAR 700 MB ONCE IT LIFTS INTO IL/IN LATER TODAY. ASSOCIATED DEEP PLUME OF UPWARD VERTICAL MOTION WITH VIGOROUS WAVE LOOKS TO LIFT ENE THROUGH THE LOCAL AREA LATER THIS AFTN/EVE WITH A 4-7 HOUR PERIOD OF ACCUMULATING SNOW ANTICIPATED. SNOWFALL RATES OF 1-2" PER HR POSSIBLE GIVEN VERY STRONG DYNAMICS AND LOW LEVEL MOISTURE TRANSPORT/CONVERGENCE WITHIN DEVELOPING TROWAL AS SFC REFLECTION DEEPENS NORTHEAST INTO NRN INDIANA/SE MI. XSECTIONS/SOUNDINGS IMPRESSIVE WITH STEEP MID LVL LAPSE RATES INTO ESPECIALLY SOUTHERN AREAS ALONG WITH A THIN LAYER WHERE THETA-E DECREASES WITH HEIGHT. GIVEN THIS CANNOT RULE OUT SOME THUNDER BUT COVERAGE AND CONFIDENCE OF OCCURRENCE REMAINS TOO LOW TO INCLUDE A THUNDER MENTION IN GRIDS. NORTHERLY TRACK OF THIS PHASED SYSTEM WILL ALLOW SOME WARMER AIR ALOFT TO WORK INTO AREAS SOUTH/ALONG THE HWY 24 CORRIDOR WHERE PRECIP MAY MIX WITH SLEET (AND LOWER CHC FOR FREEZING RAIN FAR SOUTH) TO START BEFORE DYNAMIC/EVAPORATIVE COOLING OVERWHELMS SUPPORTING A CHANGEOVER TO ALL SNOW. THIS SHOULD CUT DOWN ON SNOW TOTAL A BIT HERE...WITH HEAVIEST TOTALS EXPECTED ACROSS THE FAR NORTH WHERE PIVOT IS EXPECTED UNDER DEVELOPING 700 MB LOW TRACK. CURRENT EXPECTATIONS ARE FOR A QUICK 4-6" (LOCALIZED 6" PLUS AMOUNTS POSSIBLE) OF SNOW NORTHWEST OF HWY 24...3-5" ALONG HWY 24...AND 2-4" SOUTHEAST OF HWY 24. STRONG RISE FALL COUPLET OVERSPREADS THIS EVENING INTO THE EARLY OVERNIGHT HOURS WHICH MAY CREATE SOME BLOWING/DRIFTING SNOW FOR A TIME. AS FOR THE NEAR TERM (THIS MORNING INTO EARLY AFTN)...6-8 MB SFC 3 HR PRESSURE FALLS WILL ALLOW WINDS TO PICK UP AND GUST TO BTW 25-30 MPH LATER THIS MORNING. THIS MAY LEAD TO SOME BLOWING AND DRIFTING IN RURAL/OPEN AREAS. CHANCES FOR SNOW INCREASE WITH TIME AS 850-700 MB THETA-E GRADIENT SHIFTS EAST INTO WESTERN AREAS THIS MORNING. BAND OF SNOW TRYING TO GET STARTED ALONG THIS GRADIENT ACROSS SOUTHERN WI/NORTHERN IL AS OF THIS WRITING BUT LOSING THE BATTLE TO DRY SUB-CLOUD LAYER AT THIS TIME. RAP SATURATES OVER THE AREA WITH RELATIVE NARROW OF SNOW DEVELOPING OVER WESTERN ZONES BTW 15-18Z WHILE THE 06Z NAM SLOWER AFTER 18Z. OPTED FOR CHC POPS GIVEN THE UNCERTAINTY. && .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 343 AM EST MON FEB 17 2014 FOR TUESDAY...QUIET WEATHER IN STORE WITH DEPARTURE OF MONDAYS SNOW PRODUCER...AS SHORT WAVE UPPER RIDGING TRACKS ACROSS THE GREAT LAKES. MID/UPPER LEVEL PATTERN TO BE QUITE PROGRESSIVE THROUGH MID WEEK AS LOWER AMPLITUDE WAVE TRACKS ACROSS NORTHERN PLAINS/NORTHERN GREAT LAKES EVENTUALLY ALLOWING SFC TROUGH/COLD FRONT PASSAGE INTO THE AREA TUESDAY NIGHT/EARLY WEDNESDAY MORNING. LOW LEVEL HEIGHT GRADIENT SHOULD STEADILY STRENGTHEN ON TUESDAY IN ADVANCE OF THIS TROUGH WHICH SHOULD ALLOW FOR SOUTH WINDS TO INCREASE BY MIDDAY. CURRENTLY EXPECTING GUSTS UP TO AROUND 25 MPH WHICH COULD CREATE SOME DRIFTING CONCERNS EARLY TUESDAY AFTERNOON ACROSS OPEN AREAS FOR ESPECIALLY EAST TO WEST ORIENTED ROADWAYS. RELATIVELY LOWER SNOW TO LIQUID RATIOS AND SFC TEMPS WARMING TO ABOVE FREEZING IN THE AFTERNOON SHOULD TEND TO MITIGATE THIS CONCERN HOWEVER. THE RELATIVELY DRY AIR MASS IN PLACE SHOULD LIMIT ANY MEASURABLE PRECIP CHANCES IN ASSOCIATION WITH THE FRONT TUESDAY NIGHT...ALTHOUGH GIVEN MOISTURE PROFILES AND WEAK LIFT CANNOT COMPLETELY RULE OUT SOME VERY LIGHT PATCHY FREEZING DRIZZLE FOR A BRIEF TIME IN IMMEDIATE VICINITY OF THE FRONT. WEAK THERMAL TROUGH WILL BE IN PLACE ACROSS THE AREA FOR WEDNESDAY BEHIND THIS FRONT...WITH EVENTUAL ONSET OF STRONGER LOW LEVEL WAA AGAIN TOWARD WEDNESDAY EVENING AS LOW LEVEL ANTICYCLONE SHIFTS TO THE MID ATLANTIC STATES. PRESENCE OF LOW LEVEL THERMAL TROUGH AND VERY SHALLOW MIXED LAYER DEPTHS SHOULD RESULT IN HIGHS A DEGREE OR TWO LOWER THAN TUESDAY AFTERNOON...ALTHOUGH STILL INTO AT LEAST MID 30S MOST LOCATIONS. WITH DAYTIME TEMPS MARGINALLY ABOVE FREEZING AND NIGHTTIME TEMPS EXPECTED TO DROP BELOW FREEZING TUESDAY NIGHT/WEDNESDAY NIGHT...SNOWMELT WILL BE VERY GRADUAL AND NO SIGNIFICANT HYDROLOGIC IMPACTS ARE EXPECTED THROUGH MIDWEEK. CONCERN FOR THURSDAY WILL THEN SHIFT TO WARMING TREND AND POTENTIAL FOR SIGNIFICANT RAINFALL WHICH WILL LEAD TO INCREASED FLOOD POTENTIAL. BULK OF GUIDANCE HAS NOW SHIFTED BACK TO TREND OF SEVERAL DAYS AGO IN DEPICTING TWO DISTINCT EASTERN PACIFIC WAVES PHASING ACROSS THE UPPER MIDWEST/NORTHERN GREAT LAKES...AND PROMOTING STRONGER CYCLOGENESIS ACROSS THE WESTERN GREAT LAKES FOR THURSDAY. DETAILS STILL DIFFICULT TO PIN DOWN AT THIS POINT WITH HOW THESE WAVES WILL INTERACT AND EXTENT/TIMING OF LOW LEVEL DEEPENING...BUT HAVE SLIGHTLY TRENDED FORECAST TO THIS STRONGER EVOLUTION. STRONG LOW LEVEL THETAE ADVECTION/MOISTURE TRANSPORT TO RACE NORTHEASTWARD INTO THE LOCAL AREA BY THURSDAY MORNING WITH PTYPE CONCERNS LIKELY TO EXIST AT ONSET OF PRECIP. A BRIEF PERIOD OF -SN/-FZRA IS POSSIBLE THURSDAY MORNING BEFORE STRENGTH OF LOW LEVEL ADVECTION OVERWHELMS PROFILES AND SUPPORTS LIQUID PRECIP TYPE. AFTER THIS INITIAL WARM/MOIST ADVECTIVE SURGE THURSDAY...ITEM OF LOWER CONFIDENCE WILL BE POTENTIAL FOR ANY ADDITIONAL PRECIP INTO THURSDAY EVENING THAT MAY HAVE SOME CONVECTIVE NATURE DEPENDING ON EXACT EVOLUTION OF PATTERN. THIS WILL NEED TO BE WATCHED FOR POTENTIAL HIGHER RAINFALL AMOUNTS THAT WILL IMPACT FLOOD POTENTIAL...ESPECIALLY IN LIGHT OF SFC DEW POINTS LIKELY RISING INTO THE UPPER 30S TO LOWER 40S THAT WILL ACCELERATE SNOWMELT. LARGER SCALE FRONTAL FORCING MAY ALLOW RAIN TO PERSIST THROUGH MUCH OF THURSDAY NIGHT...ESPECIALLY ACROSS EASTERN HALF OF THE AREA. COLDER AIR TO ADVECT BACK INTO THE REGION FOR FRIDAY BEHIND THIS SYSTEM THAT MAY PROVIDE SOME BENEFIT TO RUNOFF FROM RECENT RAIN/MELTING SNOW. WILL CONTINUE WITH ESF THIS MORNING HIGHLIGHTING OVERALL POTENTIAL...BUT MUCH OF THIS WILL DEPEND ON EXACT RAINFALL AMOUNTS THURSDAY ALONG WITH HOW QUICKLY UPSTREAM SYSTEM PHASES WHICH WILL BE CRITICAL FOR TEMP/DEW PT TRENDS. PREDICTABILITY IN SMALLER SCALE WAVES IMPACTING THE AREA FOR THE WEEKEND STILL QUITE LOW AT THIS TIME...ALTHOUGH NEW 00Z GUIDANCE STILL SUPPORTS IDEA OF DEEPER MOISTURE SHUNTED WELL SOUTH OF THE AREA. HAVE CONTINUED PREVIOUS LOW CHANCE -SN/RA POPS FOR THE WEEKEND WITH A SERIES OF LOW LEVEL AMPLITUDE CLIPPER SYSTEMS POSSIBLE THROUGH THE EARLY PORTIONS OF NEXT WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1250 PM EST MON FEB 17 2014 FOCUS PRIMARILY UPON UPSTREAM/RAPIDLY DEEPENING SYSTEM ACRS CNTL IL TO TRACK INTO WRN LK ERIE BY LATE THIS EVENING. ELEVATED CONVECTIVE POTNL NECESSITATES INCLUSION OF TSSN AT KSBN...CHCS TS PSBL AT KFWA...BUT WILL HOLD FOR NOW. STILL SNOWFALL RATES 1 TO 2 INCHES PER HOUR TO BRING PERIOD OF IFR/LIFR MET CONDS ACRS NRN IN. PTYPE SHOULD REMAIN ALL SNOW AT KSBN...THOUGH FAR NRN REACH OF WARM LYR ALOFT MAY CREATE SOME MIXED SNPL AT KFWA PRIOR TO CHANGEOVER TO ALL SNOW WITH STRONG DYNAMIC COLUMN COOLING. CLOUD TOPS RAPIDLY LWR/WARM AS SYSTEM DEPARTS LATE THIS EVENING GIVING POTNL FOR SUPERCOOLED FZDZ MIX WITH LIGHT SN. KEPT AOB FUEL ATL INTO AT LEAST 14 UTC TUE PER STRENGTH OF INVERSION...LONGER THAN LATEST MODEL GUID/PRIOR FCSTS WOULD SUGGEST. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER WEATHER ADVISORY UNTIL 3 AM EST TUESDAY FOR INZ006>009- 017-018-025>027-032>034. WINTER WEATHER ADVISORY UNTIL 11 PM EST /10 PM CST/ THIS EVENING FOR INZ003>005-012>016-020-022>024. MI...WINTER WEATHER ADVISORY UNTIL 3 AM EST TUESDAY FOR MIZ079>081. WINTER WEATHER ADVISORY UNTIL 11 PM EST THIS EVENING FOR MIZ077- 078. OH...WINTER WEATHER ADVISORY UNTIL 3 AM EST TUESDAY FOR OHZ001-002- 004-005-015-016-024-025. LM...NONE. && $$ UPDATE...MURPHY SYNOPSIS...MURPHY SHORT TERM...STEINWEDEL LONG TERM...MARSILI AVIATION...MURPHY VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
447 PM EST MON FEB 17 2014 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 445 PM EST MON FEB 17 2014 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH THROUGH THE UPPER MS VALLEY WITH SEVERAL EMBEDDED SHRTWVS...THE STRONGEST OF WHICH WAS LOCATED OVER CNTRL IL. MODERATE 700-300 MB QVECTOR CONV FARTHER NORTH AHEAD OF A WEAKER SHRTWV OVER NW WI SUPPORTED LIGHT TO MODERATE SNOW FORM NRN WI THROUGH UPPER MI. TONIGHT...RADAR/SATELLITE TRENDS AND SHORT RANGE MODELS SUGGEST THAT THE HEAVIER SNOW THIS EVENING WILL REMAIN ACROSS SRN PORTION OF THE CWA...WHERE ADDITIONAL AMOUNTS OF 1 TO 3 INCHES ARE LIKELY AFTER 21Z. DEEP MOISTURE QUICKLY EXITS FROM WEST TO EAST THIS EVENING AS SHORTWAVE DEPARTS SE OF REGION AND LEVEL RIDGING BUILDS IN WITH STRONG MID LVL SUBSIDENCE AND DRYING LATE TONIGHT. TUESDAY...ANOTHER WEAK SHRTWV MOVING THROUGH NRN ONTARIO WILL BRUSH LAKE SUPERIOR. A BAND OF 290K ISENTROPIC LIFT AHEAD OF THE SHRTWV MAY PRODUCE SOME LIGHT SNOW...BUT SHOULD REMAIN MAINLY NORTH OF UPPER MI. OTHERWISE...925-850 MB RH FCST SUGGESTS THAT THERE WILL BE ENOUGH CLEARING AND SUNSHINE FOR TEMPS TO CLIMB ABOVE NORMAL INTO THE LOW AND MID 30S NORTH AND EAST AND THE UPPER 30S SOUTH. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 445 PM EST MON FEB 17 2014 PROGRESSIVE/LOWER AMPLITUDE PATTERN WILL LEAD TO A PERIOD OF WARMER WEATHER AND ABOVE NORMAL TEMPS CENTERED ON THE MIDWEEK PERIOD. HOWEVER...THE WARMTH WILL BE SHORT-LIVED. ALL INDICATIONS POINT TOWARD THE RETURN OF A STRONG RIDGE CENTERED ALONG OR SLIGHTLY INLAND OF THE WEST COAST THIS WEEKEND INTO NEXT WEEK. MANY OF THE GEM ENSEMBLES OVER THE LAST FEW DAYS HAVE INDICATED A VERY COLD REGIME FOR LATE FEB NEXT WEEK...AND NOW TODAYS 12Z ECMWF SHOWS A BITTERLY COLD AIR MASS DUMPING INTO THE UPPER LAKES DURING THE MIDDLE OF NEXT WEEK WITH A REINFORCING SHOT UPSTREAM YET. DETERMINISTIC GFS RUNS OUT TO 16 DAYS HAVE SHOWN WIDE FLUCTUATION IN THE LAST DAY OR SO... BUT RUNS KEEP APPEARING THAT MAINTAIN A VERY AMPLIFIED PATTERN OF WRN RIDGE/ERN TROF...LEADING TO A VERY COLD PERIOD FOR THE UPPER LAKES. IN ANY EVENT...AS THIS CHANGE BACK TO A COLD PATTERN GETS UNDERWAY...ATTENTION WILL BE ON AN AMPLIFYING TROF SHIFTING ACROSS THE CONUS DURING THE MID AND LATE WEEK. OVER THE LAST SEVERAL DAYS...MODELS HAVE STRUGGLED WITH PHASING OF SHORTWAVES WITHIN THE DEEPENING TROF. HOWEVER...WITH TODAYS 12Z MEDIUM RANGE MODEL RUNS...THERE ARE SOLID TRENDS TOWARD MUCH BETTER AGREEMENT ON A SRN STREAM WAVE LIFTING NE AND PHASING WITH A NRN BRANCH WAVE OVER AND JUST NE OF THE GREAT LAKES. THIS WILL LEAD TO THE ONLY SIGNIFICANT PCPN EVENT (SNOW AND MIXED PCPN) DURING THE LONG TERM PORTION OF THE FCST. OUTSIDE OF THIS ONE EVENT...NOT MUCH PCPN IS EXPECTED DURING THE LONG TERM. BEGINNING TUE NIGHT...NEXT SHORTWAVE TROF WILL QUICKLY SHIFT ACROSS THE WRN GREAT LAKES. WITH SEVERAL DISJOINTED VORT CENTERS COMPRISING THE TROF...NOT EXPECTING MUCH IF ANY PCPN...ESPECIALLY WITH DEEP LAYER FORCING/MID LEVEL MOISTURE EXITING TO THE E OF THE AREA ALREADY IN THE EVENING. BEFORE THAT HAPPENS...MAY SEE A LITTLE BIT OF -SN/FLURRY ACTIVITY OVER THE E EARLY IN THE EVENING. AFTER THAT...QUESTION IS WHETHER THERE MIGHT BE SOME FLURRIES OR MORE LIKELY -FZDZ AS TEMP PROFILE IN LINGERING GENERALLY SHALLOW MOISTURE IS ABOVE -10C. UNDER W TO WNW LOW-LEVEL WINDS...BEST CHANCE WOULD BE OVER THE UPSLOPE AREAS OF WRN UPPER MI AND PERHAPS THE FAR NE FCST AREA AS WINDS VEER WNW THERE LATER IN THE NIGHT. SINCE ANY ADDITIONAL MOISTENING THAT COULD BE PROVIDED BY LAKE SUPERIOR IS VERY LIMITED AS THE LAKE IS NEARLY COMPLETELY ICED OVER...WILL HOLD OFF ON INCLUDING A MENTION OF -FZDZ. TUE NIGHT WILL BE ONE OF THE WARMER NIGHTS IN QUITE A WHILE UNDER PACIFIC AIR MASS WITH WINDS HELPING TO KEEP TEMPS UP. EXPECT MINS IN THE TEENS TO LOWER 20S. WED WILL BE A DRY DAY AS SHORTWAVE TROF SHIFTS E OF THE AREA AND SHORTWAVE RIDGING BUILDS INTO THE WRN LAKES. WHILE THERE MIGHT BE SOME LOW CLOUDS LINGERING INTO WED MORNING...EXPECT MOST AREAS TO SEE A GOOD DISPLAY OF SUNSHINE WED. HIGHER MID TO LATE FEB SUN ANGLE WORKING ON THE LOWER ALBEDO FORESTED TERRAIN WILL HELP TEMPS RISE INTO THE 30S ACROSS THE BOARD. MAY NOT BE OUT OF THE QUESTION FOR A FEW LOCATIONS TO REACH 40F WHERE DOWNSLOPING OCCURS. WITH W TO WNW WINDS FOR MUCH OF THE DAY...TEMPS WILL BE COOLEST NEAR LAKE SUPERIOR OVER WRN UPPER MI AND OVER THE NE FCST AREA. IN THOSE LOCATIONS... TEMPS SHOULDN`T RISE ABOVE FREEZING. AS ALLUDED TO ABOVE...MEDIUM RANGE GUIDANCE HAS STRONGLY TRENDED TOWARD MUCH BETTER AGREEMENT WITH THE DETAILS OF AMPLIFYING TROF SHIFTING ACROSS THE CONUS MID AND LATE WEEK. ALTHOUGH THE MODEL AGREEMENT THAT HAS APPEARED WITH TODAYS 12Z MODEL RUNS IS RATHER REMARKABLE GIVEN THE VERY RECENT DISAGREEMENT...THE SHORTWAVES INVOLVED ARE STILL IN THE GULF OF ALASKA AND ALEUTIANS...SUGGESTING CONTINUED ADJUSTMENTS ARE IN THE OFFING. THAT SAID...THE GEM/GFS/ECMWF ARE IN EXCELLENT AGREEMENT TODAY SHOWING A SRN STREAM SHORTWAVE MOVING OUT OVER THE SRN PLAINS THU AND THEN LIFTING NE AND PHASING WITH NRN STREAM ENERGY OVER THE UPPER MISSISSIPPI VALLEY. RESULT IS A SFC LOW OVER THE SRN PLAINS THU MORNING LIFTING NE ACROSS NW IL AND THEN RAPIDLY DEEPENING AS IT MOVES JUST E OF KGRB THEN ACROSS ERN LAKE SUPERIOR THU NIGHT. WITH 12HR HEIGHT FALLS OF 250-300M AT 500MB...THIS WILL BE A VERY DYNAMIC SYSTEM WITH A RAPIDLY ORGANIZING/INTENSIFYING PCPN SHIELD AS IT MOVES ACROSS THE UPPER LAKES. WITH SYSTEM TAPPING A GOOD FEED OF GULF MOISTURE... STRONG DYNAMICS WILL MAKE THIS A SIGNIFICANT PCPN PRODUCER ACROSS MUCH OF UPPER MI. BASED OFF 12Z MODELS WHICH ARE IN GOOD AGREEMENT...PTYPE SHOULD BE JUST SNOW W OF LINE ROUGHLY FROM JUST NW MENOMINEE TO AROUND MUNISING WITH A WINTRY MIX TO THE E FOR AT LEAST A TIME. HOWEVER...UNTIL SHORTWAVES INVOLVED ARRIVE IN THE CONUS/CANADA...EXPECT SOME FLUCTUATION IN SYSTEM STRENGTH/TRACK AND THERMAL FIELDS/PTYPES. POPS WILL BE RAISED ACROSS THE BOARD TO CATEGORICAL FOR AT LEAST A PORTION OF THU AFTN/NIGHT. DEPENDING ON EXACTLY HOW STRONG THE LOW BECOMES...WINDS/BLSN COULD BECOME SIGNIFICANT ON THE BACKSIDE. RIGHT NOW...IT APPEARS BACKSIDE WINDS WILL BE FROM A W TO WNW DIRECTION. IF SO...THOUGH FALLING SNOW WILL BE MUCH LIGHTER...BLIZZARD CONDITIONS WILL BE POSSIBLE OVER THE KEWEENAW WITH THE ADDED COMPONENT OF BLSN OFF LAKE SUPERIOR ICE COVER. STRONG WINDS WILL LIKELY LOOSEN UP ICE COVER AND CREATE SUFFICIENT BREAKS FOR SOME LES OFF LAKE SUPERIOR AFTER THE SYNOPTIC MOISTURE PULLS OUT FRI AND 850MB TEMPS FALL INTO THE MID -TEENS C. ARCTIC AIR BECOMES RE-ESTABLISHED OVER THE GREAT LAKES OVER THE WEEKEND INTO NEXT WEEK. HOW COLD IS UNCERTAIN...BUT TEMPS SHOULD BE SOLIDLY BLO NORMAL WITH A TREND TO COLDER CONDITIONS EARLY NEXT WEEK AND BEYOND. WHILE THERE MAY BE SOME -SN AT TIMES AND PROBABLY SOME LIMITED LAKE EFFECT OFF LAKE SUPERIOR DUE TO FRACTURED ICE COVER/SMALL OPEN WATER AREAS...NO PCPN OF SIGNIFICANCE IS ANTICIPATED AT THIS POINT SAT THRU MON. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 110 PM EST MON FEB 17 2014 WIDESPREAD SNOW WILL BRING IFR CONDITIONS TO THE TAF SITES THIS AFTERNOON INTO THIS EVENING. THERE MAY ALSO BEE SOME PERIODS OF LIFR VSBYS/CIGS BEFORE ALL SITES IMPROVE TO MVFR MONDAY EVENING. HOWEVER...CONFIDENCE WITH THE TIMING/DURATION OF THE PERIODS IS LOW. MVFR CONDITIONS OVERNIGHT ARE EXPECTED TO IMPROVE TO VFR TUE MORNING AS DRIER MOVES IN BEHIND A FRONTAL SYSTEM. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 445 PM EST MON FEB 17 2014 WINDS ARE FORECAST TO BE LESS THAN 30 KTS THROUGH WED. THERE IS THE POTENTIAL FOR A STRONG LOW PRESSURE SYSTEM TO MOVE THROUGH LAKE SUPERIOR THURSDAY NIGHT AND INTO NORTHERN ONTARIO FRIDAY. THIS WOULD LIKELY BRING A PERIOD OF NORTHWEST TO WEST GALES LATE THURSDAY NIGHT THROUGH FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 1 AM EST TUESDAY FOR MIZ006-007- 014-085. WINTER WEATHER ADVISORY UNTIL 10 PM EST /9 PM CST/ THIS EVENING FOR MIZ001-003>005-010>013-084. WINTER WEATHER ADVISORY UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR MIZ002-009. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...ROLFSON AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
353 PM EST MON FEB 17 2014 .SHORT TERM... AFTERNOON THROUGH TONIGHT THE WINTER WEATHER ADVISORY WILL REMAIN IN EFFECT TONIGHT FOR HIGH END ADVISORY SNOW ACCUMULATION. THE RANGE OF 3 TO 6 INCHES WILL LIKELY VERIFY CLOSER TO THE 6 INCH END OF THE RANGE FOR MOST LOCATIONS. LOCALLY HIGHER AMOUNTS AND A SHORT FUSED WARNING UPGRADE ALSO REMAINS IN PLAY AS THE POSITION AND CHARACTER OF MESOSCALE FORCING BECOMES CLEARER. THIS WOULD MOST LIKELY BE IN THE TRI CITIES TO NORTHERN THUMB BASED ON OBSERVATIONS AS THEY BECOME AVAILABLE DURING THE LATE AFTERNOON INTO EARLY EVENING. THE MAIN UNCERTAINTY WITH AN UPGRADE LIES WITH THE PROGRESSION VERSUS PIVOT OF THE DEFORMATION AXIS ON THE NORTH FLANK OF THE SYSTEM AND THE NORTHWARD PUSH OF THE DRY SLOT. OBSERVATIONS WILL BE MONITORED FOR A PIVOT WHICH WOULD PERMIT HIGHER RATES FOR A LONGER PERIOD OF TIME AND HIGHER SYSTEM TOTALS AND/OR 6 INCH AMOUNTS COMING IN CLOSER TO 6 TO 9 HOUR TIME PERIOD. FARTHER SOUTH, A CONVECTIVE COMPONENT IN THE FORCING WILL BRING HIGH SNOWFALL RATES AND EVEN SOME GRAUPEL/SNOW PELLETS WITH A RUMBLE OF THUNDER AT TIMES BEFORE THE MID LEVEL DRY SLOT CONFINES TOTAL ACCUMULATION CLOSER TO 4 INCHES. MID AFTERNOON SATELLITE IMAGERY SHOWS THE LOW PRESSURE SYSTEM OVER ILLINOIS/INDIANA COMING TOGETHER IN A STRONGLY DYNAMIC FASHION. VISIBILITY NEAR ZERO IN SURFACE OBSERVATIONS WITH SEVERAL CLUSTERS OF CG LIGHTNING STRIKES DEPICTS THE CONVECTIVE NATURE OF THE SITUATION, AS DOES THE SPECIAL 18Z KILX SOUNDING WITH BORDERLINE DRY ADIABATIC LAPSE RATES IN THE 700-500 MB LAYER. NEAR TERM MODEL FIELDS HAVE PICKED UP ON THIS AS A STRONG COMBINATION OF MID LEVEL DCVA AND LOW LEVEL THETA-E ADVECTION ON 850 MB WIND PUSHING 50 KNOTS. THE WIND FIELD WILL EVENTUALLY GET CONVERTED TO TROWAL FORCING WITH SPECIFIC HUMIDITY SETTLING IN AROUND 3 G/KG. THE TROWAL/DEFORMATION AXIS IS EXPECTED TO SET UP NORTH OF THE INTERSTATE 69 CORRIDOR AS THE SURFACE LOW DROPS FROM 1007 MB TO NEAR 1000 MB OVER THE EAST SHORE OF LAKE ST CLAIR BY MIDNIGHT. AS MENTIONED ABOVE, THERE WILL BE CONVECTIVE INSTABILITY BOTH WITHIN THE WARM ADVECTION PATTERN AND ON THE INTERIOR FLANK OF THE TROWAL/THETA-E RIDGE. THIS THERMODYNAMIC ENVIRONMENT COUPLED WITH THE STRONG WIND FIELD WILL RESULT IN SNOWFALL RATES IN THE 1-2 INCH PER HOUR RANGE. IN ADDITION, MODEL SOUNDINGS INDICATE FAVORABLE TEMPERATURE AND MOISTURE PROFILES THAT DEPICT A DGZ DEPTH ROUGHLY FROM 600 TO 800 MB THAT SHOULD SUPPORT SNOW RATIO IN THE 10-13:1 RANGE. THE NAM AND THE RAP MODELS SEEMINGLY HAVE ALSO PICKED UP ON THE COMBINATION OF HIGHER MOISTURE CONTENT AND STRONG DYNAMIC FORCING REFLECTED IN LIQUID EQUIVALENT QPF RANGING FROM 0.6 TO 0.8 IN THE 12 HOUR PERIOD FROM 18Z TO 06Z TONIGHT. THIS ILLUSTRATES THE POTENTIAL FOR OVERACHIEVEMENT SHOULD MESOSCALE FORCING STALL OVER ANY ONE REGION OF SE MICHIGAN DURING THE EVENING. THE SYSTEM WILL THEN MOVE EASTWARD ENOUGH OVERNIGHT FOR SNOW TO DIMINISH ON THE WESTERN FLANK OF THE UPPER CIRCULATION BY SUNRISE TUESDAY MORNING. && .LONG TERM...TUESDAY THROUGH SUNDAY PROGRESSIVE LOW AMPLITUDE LONGWAVE PATTERN WILL CONTINUE THROUGH THE MID WEEK BEFORE BROAD TROUGH SETS UP ACROSS MUCH OF THE CENTRAL CONUS AND GREAT LAKES THROUGH THE WEEKEND. THE ENERGETIC JET WILL SHIFT FAR ENOUGH NORTH TO ALLOW A WARMUP THROUGH THE MID WEEK PERIOD WITH TEMPS IN THE MID 30S AND EVEN NEAR 40F BEFORE THE NEXT TROUGH AND STRONG SYSTEM PUSHES THE MILD AIR SOUTH DROPPING US BACK INTO THE 20S. THE DIFFICULTY IN THE TEMP FORECAST WILL BE TAKING INTO ACCOUNT THE DEEP SNOWPACK THAT IS PRESENT ACROSS THE AREA. THERE MAY BE SOME LINGERING LIGHT SNOW SHOWERS OR FLURRIES OVER THE AREA TUESDAY MORNING AS THE BACK EDGE OF MONDAYS SYSTEM HOLDS OVER THE AREA. AS THIS EXITS...A FRONTAL BOUNDARY EXTENDING SOUTHEAST FROM A MUCH LARGER SYSTEM OVER CENTRAL CANADA WILL LIFT NORTH THROUGH THE GREAT LAKES. THIS...ALONG WITH A SHORTWAVE RIDGE BUILDING ACROSS THE AREA...WILL LEAD TO INCREASING SW FLOW AND A WAA PATTERN. LOW LEVEL TEMPS WILL CLIMB FROM -8C/-12C AT 850MB/925MB CURRENTLY UP TO AROUND 3-5C BY LATE TUESDAY AFTERNOON. MODEL SOUNDING KEEP THE BOUNDARY MUCH COOLER THOUGH WITH TEMPS STILL BELOW 0C. GUSTY WINDS SHOULD BE ABLE TO MIX SOME OF THAT DOWN BUT THE COLD DEEP SNOWPACK WILL WORK AGAINST IT MUCH OF TIME. WITH THE WARMEST AIR TAKING SO LONG TO GET INTO THE AREA...HAVE KEPT HIGH TEMPS AROUND THE MID 30S FOR NOW. WEDNESDAYS FORECAST WILL ALSO BE A TRICKY ONE AS A COLD FRONT WILL SWEEP THROUGH THE AREA IN THE MORNING. THERE IS A LOW CHANCE THAT WE COULD SEE SOME SNOW FLAKES FROM THIS FRONT BUT NOT MUCH IN THE WAY OF ACCUMULATIONS. LOW LEVEL THERMAL PROFILE DOES NOT TANK MUCH AS RIDGING QUICKLY BUILDS IN THE WAKE OF THIS FRONT. MID LEVELS DO COOL QUITE A BIT THOUGH. WITH SFC HIGH PRESSURE BRINGING MOSTLY CLEAR SKIES...SHOULD NOT BE TOO HARD TO GET BACK INTO THE MID/UPPER 30S EVEN WITH SFC-800MB TEMPS HOVERING AROUND 0C. POTENTIAL TO ADD A DEGREE OR TWO TO THE FORECAST BUT ONCE AGAIN WOULD LIKE TO SEE HOW SEVERE THE SNOW PACK AFFECTS THINGS BEFORE GOING TOO HIGH. LOW PRESSURE ORIGINATING FROM THE TEXAS PANHANDLE WILL TRACK NORTHEAST TOWARD THE GREAT LAKES BY THURSDAY. THE TRACK AND ORIENTATION OF THIS SYSTEM WILL ALLOW MOISTURE FROM THE GULF OF MEXICO TO ENHANCE QPF AMOUNTS AND ALSO WARM THE SYSTEM CONSIDERABLY. EXPECTING BETWEEN 0.5 AND 1.0 INCHES OF RAINFALL ALONG WITH CONSIDERABLE SNOWMELT FROM THIS SYSTEM...WHICH MAY LEAD TO RIVER/AREAL FLOOD ISSUES. AVERAGE SNOW CORES ACROSS THE REGION ARE OVER 3 INCHES OF LIQUID EQUIVALENT IN 16 INCHES OF SNOW DEPTH...EXCLUDING THE 3-6 INCHES EXPECTED TONIGHT. && .MARINE... A LOW PRESSURE SYSTEM WILL TRACK FROM SOUTH OF LAKE MICHIGAN ACROSS TO WESTERN LAKE ERIE AND NORTHEAST THROUGH LAKE ST CLAIR TONIGHT. THIS WILL PRODUCE A PERIOD OF HEAVY SNOW THIS EVENING. GUSTY WESTERLY WINDS WILL FOLLOW THE SYSTEM ON TUESDAY MORNING WITH THE POTENTIAL TO BRIEFLY TOP 25 KNOTS OVER LAKE ERIE AND LAKE ST CLAIR. WINDS WILL RELAX SOME TUESDAY AFTERNOON AS A RIDGE OF HIGH PRESSURE BUILDS INTO THE REGION. A WEAK COLD FRONT COULD AGAIN LEAD TO GUSTY WINDS ON WEDNESDAY BUT THIS TIME OUT OF THE NORTHWEST. SUBSTANTIAL ICE COVERAGE ACROSS ALL MARINE AREAS WILL KEEP WAVES ABSENT FROM ALL FORECAST PRODUCTS. && .AVIATION...ISSUED 1258 PM EST MON FEB 17 2014 //DISCUSSION... VFR CONDITIONS WILL BE IN PLACE THROUGH MID AFTERNOON FOLLOWED BY QUICKLY DETERIORATING CEILING AND VISIBILITY AS SNOW SPREADS OVER THE REGION. LATE AFTERNOON TIMING REMAINS ON TRACK WITH FAIRLY UNIFORM ONSET AND 3-6 INCH TOTAL ACCUMULATION EXPECTED ACROSS THE TERMINAL CORRIDOR, LIKELY VERIFYING AT THE HIGH END OF THE RANGE. THE SNOW WILL BE INTERMITTENT IFR UNTIL LOW LEVELS SATURATE AND THEN WILL RAMP UP CONSIDERABLY DURING THE EVENING ROUGHLY DURING THE 00Z-06Z PERIOD WHEN LIFR IS EXPECTED. THERE IS ALSO POTENTIAL FOR VISIBILITY NEAR ZERO AT TIMES BUT TIMING ON THIS REMAINS A BIT UNCERTAIN FOR INCLUSION IN THIS FORECAST ISSUANCE. LATER UPDATES COULD INCLUDE A VLIFR WINDOW PERHAPS AT DTW INITIALLY AND THEN AT POINTS FARTHER NORTH DEPENDING ON AFTERNOON OBSERVATIONS UPSTREAM. THE SNOW WILL DIMINISH DURING THE OVERNIGHT AND GRADUALLY GIVE WAY TO VFR CEILING DURING TUESDAY MORNING ACCOMPANIED BY A GUSTY WEST WIND. FOR DTW... VFR CEILING WILL DROP QUICKLY BELOW 5000 FEET AFTER 20Z WITH ONSET OF LIGHT SNOW. RATES WILL THEN INCREASE RAPIDLY TOWARD 00Z WITH UP TO AN INCH PER HOUR EXPECTED AT PEAK INTENSITY 00Z-04Z. TOTAL ACCUMULATION OF 3-6 INCHES THAT HAS BEEN CALLED FOR WILL LIKELY VERIFY CLOSER TO THE 6 INCH END OF THE RANGE. //DTW THRESHOLD THREATS... * HIGH CONFIDENCE IN CEILING BELOW 5000 FT LATE AFTERNOON THROUGH TONIGHT. * HIGH CONFIDENCE IN PRECIPITATION TYPE AS SNOW. * MEDIUM CONFIDENCE IN VISIBILITY 1/2 MILE OR LESS IN HEAVY SNOW DURING THE EVENING. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054-MIZ055- MIZ060-MIZ061-MIZ062-MIZ063-MIZ068-MIZ069-MIZ070-MIZ075-MIZ076- MIZ082-MIZ083...UNTIL 4 AM TUESDAY. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...BT LONG TERM....DRK/MM MARINE.......DRK AVIATION.....BT YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
111 PM EST MON FEB 17 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 522 AM EST MON FEB 17 2014 09Z WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL PATTERN ACROSS THE WEST AND CENTRAL CONUS WITH A MID/UPPER LEVEL TROUGH AND SEVERAL EMBEDDED SHRTWVS EMERGING FROM THE NRN ROCKIES INTO THE WRN PLAINS. WAA/ISENTROPIC LIFT AHEAD OF THIS SHORTWAVE TROUGH HAS ALLOWED MID-HIGH CLOUDS TO SPREAD INTO THE FCST AREA FM THE WEST. AS A RESULT...MUCH BELOW ZERO TEMPS FM LAST EVENING OVER CENTRAL AND EASTERN COUNTIES OF THE CWA HAVE BEGUN TO MODERATE ABV ZERO AT MANY LOCATIONS. SOME LIGHT SNOW IS ALSO NOW APPEARING ON RADAR AND SFC OBS OVER NCNTRL WI AND FAR WRN UPR MI. TODAY...MODELS IN GENERALLY GOOD AGREEMENT ON DEPICTION/MOVEMENT OF MAIN SHORTWAVE NOW OVER WRN NEBRASKA TRACKING IT AND ASSOC SFC LOW ESE THROUGH CNTRL ILLINOIS AND NRN INDIANA LATE AFTERNOON/EARLY EVENING. NORTHERN SHORTWAVE OVER THE DAKOTAS APPEARS TO BECOME MORE SHEARED OUT WITH TIME AS IT APPROACHES THE WRN LAKES LATE THIS AFTERNOON. THIS IS REFLECTED IN 700-300 MB LAYER Q-VECTORS WHICH SHOWS BEST CONV/LIFT GENERALLY PASSING SOUTH AND EAST OF THE FCST AREA THIS AFTERNOON. ALSO A LIMITING FACTOR FOR HEAVY SNOW TODAY OVER OUR AREA IS THE VERY DRY AIRMASS ALREADY IN PLACE AS NOTED ON 00Z GRB AND APX SOUNDINGS. CONSEQUENTLY..IT WILL TAKE LONGER FOR COLUMN TO MOISTEN FM ISENTROPIC ASCENT AS THUS WILL LIKELY LIMIT SNOW AMOUNTS SOMEWHAT. CONTINUED THE PREV FCST TREND OF GOING ON THE LOWER END OF MODEL GUIDANCE FOR QPF AMOUNTS RANGING FROM .15 INCH FAR EAST TO NEARLY .3 INCH NEAR MNM. USING COBB METHOD AVERAGED SLR VALUES AROUND 17:1...TOTAL SNOW AMOUNTS FROM THIS SYSTEM WILL LIKELY FALL INTO THE 3 TO 5 INCH RANGE ACROSS MUCH OF THE AREA...BUT FAR NE CWA MAY STRUGGLE TO REACH MINIMAL ADVISORY CRITERIA OF 3 INCHES DUE TO EFFECTS OF ATTENDANT DRY AIR DELAYING ARRIVAL OF PCPN UNTIL MAINLY AFTERNOON. SSE WINDS ARE EXPECTED TO INCREASE AND GUST NEAR 25 MPH AT TIMES BY LATE MORNING/AFTERNOON WHICH MAY CONTRIBUTE TO SOME BLSN BUT NOTHING OF GREAT SIGNIFICANCE. CONTINUED THE WINTER WEATHER ADVISORIES ACROSS THE AREA BUT GIVEN POTENTIAL LIMITING FACTORS MENTIONED ABOVE...LOWERED HIGH END OF ADVISORY RANGE TO 5 INCHES FOR WEST AND CENTRAL COUNTIES AND WENT GENERALLY 2 TO 4 INCHES FOR ERN COUNTIES. TONIGHT...DEEP MOISTURE QUICKLY EXITS FROM WEST TO EAST THIS EVENING AS SHORTWAVE DEPARTS SE OF REGION AND MODEL SOUNDINGS SHOW GOOD MID-LVL SUBSIDENCE/DRYING LATE TONIGHT. WAA DEVELOPING FROM THE WEST LATE TONIGHT AHEAD OF NEXT SHORTWAVE APPROACHING FM THE NRN PLAINS MAY BRIEFLY ALLOW FOR SOME PATCHY FREEZING DRIZZLE TO FORM OVER ERN COUNTIES IN UPSLOPE SOUTHERLY FLOW AS DGZ DRIES OUT...BUT STILL NOT CONFIDENT ENOUGH TO INCLUDE IN FCST. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 522 AM EST MON FEB 17 2014 ZONAL FLOW BRINGS MULTIPLE SHORTWAVES ACROSS THE REGION THROUGH THE UPCOMING WEEK. STRONGEST WAVE BEYOND TODAY IS STILL ON TRACK TO IMPACT GREAT LAKES THURSDAY AND THURSDAY NIGHT THOUGH CURRENT INDICATIONS ARE THAT BIGGEST IMPACT WILL STAY MORE OVER THE OHIO VALLEY AND LOWER GREAT LAKES. OPPORTUNITY TO FINALLY REACH ABOVE FREEZING WFO MARQUETTE WILL BE THE MIDDLE OF THIS WEEK...THOUGH IT IS NOT LOOKING AS SURE AS IT DID THE LAST COUPLE DAYS. WHATEVER WARM UP OCCURS WILL NOT LAST AS IN WAKE OF THE LATE WEEK SYSTEM LARGER SCALE TROUGHING WITH COLDER TEMPERATURES DEVELOPS OVER MUCH OF THE CNTRL CONUS BY NEXT WEEKEND. TUESDAY AND TUESDAY NIGHT...SHORTWAVE AND SFC LOW THAT ARE BRINGING SNOW TO REGION TODAY HEAD OFF ACROSS NEW ENGLAND. WESTERLY FLOW ALOFT WILL BRING ADDITIONAL SHORTWAVES FROM THE NORTHERN PLAINS TO THE WESTERN GREAT LAKES BY TUESDAY AFTN. STRONGEST WAVE ON TUESDAY CROSSES SOUTHERN MANITOBA INTO ONTARIO...WITH ASSOCIATED 995-1000MB SFC LOW MOVING ACROSS ONTARIO IN THE AFTN...TO THE NORTH OF LK SUPERIOR. SOUNDINGS SHOW PLENTY OF MID LEVEL MOISTURE TO H7 BUT ALSO HAVE A LOT OF DRY AIR BLO THAT. ONLY EXCEPTION IS OVER EASTERN CWA WHERE THERE MAY BE ENOUGH LOW-LEVEL MOISTURE TO RESULT IN SOME FREEZING DRIZZLE IN THE MORNING. H85 FRONT LIKELY WILL BE VCNTY OF SOUTHERN LK SUPERIOR SO KEPT SLIGHT CHANCES MAINLY OVER LK SUPERIOR AND IN THE FAR NORTH CWA. WARMEST TEMPS OVER FAR WEST WHERE MAY BE SOME BKN SUNSHINE TO START THE DAY. H925-H9 TEMPS STILL AROUND 0C SO WOULD NOT TAKE MUCH MIXING TO PUNCH TEMPS INTO AT LEAST MID 30S. FARTHER TO THE EAST...MORE CLOUDS AND SW WINDS OFF MAINLY ICE COVERED LK MICHIGAN SHOULD KEEP TEMPS BLO FREEZING. GENERALLY QUIET TUESDAY NIGHT THOUGH WILL HAVE TO WATCH WESTERN CWA LATE AS THERE MAY BE ENOUGH LOW-LEVEL MOISTURE AND UPSLOPE IN WAKE OF SFC TROUGH WORKING THROUGH TO PRODUCE LGT PRECIP. SOUNDINGS WOULD SUPPORT SOME RISK OF FREEZING DRIZZLE WITH LIMITED MOISTURE IN DGZ...THAT IS IF THERE IS SUFFICIENT MOISTURE IN THE LOW-LEVELS. WEDNESDAY...EARLIER IT LOOKED AS THERE WOULD BE NW WINDS IN WAKE OF TROUGH ON TUESDAY TO RESULT IN COOLING FOR THE NORTH OFF ICE COVERED LK SUPERIOR. WINDS IN BLYR NOW MORE WRLY WHICH OPENS POSSIBILITY OF WARMER TEMPERATURES OVER MUCH OF CWA...EXCEPT ALONG IMMEDIATED LK SUPERIOR SHORE OVER WESTERN CWA AND ACROSS KEWEENAW PENINSULA. BIAS CORRECTED GUIDANCE INDICATED MID 30S FOR MOST AREAS WITH EVEN TEMPS AROUND 40 IN THE SCNTRL. USED THIS SOLN AS A BLEND INTO PREVIOUS FORECAST WHICH RESULTED IN SOLID MID 30S FOR GOOD PART OF CWA. COULD BE SOME LOW-LEVEL MOISTURE TO BEGIN THE DAY...BUT THIS SHOULD SCOUR OUT BY AFTN. OVERALL A QUIET WEATHER DAY OUT AHEAD OF STRONGER LOW-MID LEVEL TROUGHING DEVELOPING OVER THE CNTRL CONUS. THURSDAY AND FRIDAY...FATE OF THE LATE WEEK SYSTEM IS STILL CLOUDED WITH MUCH UNCERTAINTY AT THIS POINT. ECMWF AND GFS TRENDED BACK TO MORE WRAPPED UP AND WETTER SYSTEM AS SOUTHERN BRANCH SHORTWAVE DOMINATES AND ALLOWS THE LARGER SCALE SHORTWAVE TROUGH TO BECOME MORE NEGATIVELY TILTED AS IT SWEEPS ACROSS UPPER GREAT LAKES. RESULTING SFC LOW DEEPENS TO SUB 980MB LOW OVER UPPER LAKES BY THURSDAY NIGHT. AS ALLUDED TO YDY...SHORTWAVES THAT HELP FORM THIS SYSTEM ARE STILL AROUND THE ALLUTIANS AND MAYBE EVEN FARTHER WEST THAN THAT OVER NORTHERN RUSSIA. SO...ALTHOUGH THE 00Z ECMWF SOLUTION COULD OCCUR AS IT SHOWED SOMETHING SIMILAR TWO DAYS AGO...IT IS ESSENTIALLY ONE OF MANY SOLNS THAT REPRESENT THE MODEL ENSEMBLE AT THIS POINT. ONLY CHANGE THAT WAS MADE COMPARED TO CONSENSUS WAS TO LINGER CHANCE POPS ON THURSDAY NIGHT IN CASE THE SLOWER/WRAPPED UP IDEA IS CORRECT. ALSO BROUGHT CHANCE FOR RAIN FARTHER NORTH OVER EASTERN CWA. SEEMS THAT IF THE WARMER IDEA IS RIGHT...FZRA COULD ALSO BE AN ISSUE TOO DUE TO LIMITED LOW-LEVEL WARM AIR ADVECTION BLO H85 OR MAYBE JUST FROM THE RAIN FREEZING ON SUB FREEZING ROAD SURFACES DUE TO THE PERSISTENT CHILL THAT HAS BEEN WITH US SINCE EARLY DECEMBER. EVEN THOUGH THE SPECIFICS WITH THIS SYSTEM ARE FAR FROM CERTAIN AND WILL LIKELY CHANGE UNTIL LATER THIS WEEK...THINK IT IS WORTH A HEADS UP MENTION IN THE HAZARDOUS WEATHER OUTLOOK. PRIMARY ISSUE INTO FRIDAY WILL BE STRONGER WINDS CLOSER TO LK SUPERIOR WITH SMALL CHANCES OF SNOW SHOWERS IN LINGERING CYCLONIC MOIST FLOW ON BACKSIDE OF THE DEPARTING LOW PRESSURE SYSTEM. THE WARM UP WILL BE OVER BUT TEMPS WILL BE AROUND NORMAL WITH READINGS IN THE MID TO UPPER 20S. UNCERTAINTY HIGH BEYOND FRIDAY. MODEL CONSENSUS WAS USED FOR NOW WHICH FEATURES PLETHORA OF SLIGHT CHANCE POPS. SEEMS THAT IDEA OF SHORTWAVE LIFTING BACK ACROSS THE AREA AND BRINGING SOME LGT SNOW IS OFF THE TABLE NOW AS THAT SYSTEM IS MUCH WEAKER AND FCST TO REMAIN WELL TO THE SOUTH AND EAST OF CWA IF IT IS THERE AT ALL. TEMPS SATURDAY IN THE TEENS AND LOWER 20S...WITH MORE NOTABLE COOLING FOR SUNDAY WITH HIGHS IN THE LOWER TO MIDDLE TEENS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 110 PM EST MON FEB 17 2014 WIDESPREAD SNOW WILL BRING IFR CONDITIONS TO THE TAF SITES THIS AFTERNOON INTO THIS EVENING. THERE MAY ALSO BEE SOME PERIODS OF LIFR VSBYS/CIGS BEFORE ALL SITES IMPROVE TO MVFR MONDAY EVENING. HOWEVER...CONFIDENCE WITH THE TIMING/DURATION OF THE PERIODS IS LOW. MVFR CONDITIONS OVERNIGHT ARE EXPECTED TO IMPROVE TO VFR TUE MORNING AS DRIER MOVES IN BEHIND A FRONTAL SYSTEM. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 522 AM EST MON FEB 17 2014 WINDS ARE FORECAST TO BE LESS THAN 30 KTS THIS WEEK. LOW PRESSURE SYSTEM MOVING THROUGH LATE IN THE WEEK MAY RESULT IN STRONGER WINDS THAN CURRENTLY FORECAST...MAINLY ON THURSDAY AFTERNOON AND THURSDAY NIGHT. GALES MAY EVEN OCCUR. ONCE THIS LOW LIFTS TO THE NORTH...WEST WINDS TO 30 KTS OR GALES APPEAR LIKELY ON FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL 1 AM EST TUESDAY FOR MIZ006-007- 014-085. WINTER WEATHER ADVISORY UNTIL 10 PM EST /9 PM CST/ THIS EVENING FOR MIZ001-003>005-010>013-084. WINTER WEATHER ADVISORY UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR MIZ002-009. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...VOSS LONG TERM...JLA AVIATION...JLB MARINE...JLA
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
331 PM CST MON FEB 17 2014 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 245 PM CST MON FEB 17 2014 UPPER TROUGH WORKING ACROSS THE AREA THIS AFTERNOON HAS GONE QUITE NEGATIVE ON US...WHICH HAS RESULTED IN THE SNOW AND CLOUDS FILLING BACK IN TO THE WEST. THE WRN EDGE OF THE SNOW IS FAIRLY SHARP AND IS ASSOCIATED WITH A WARM FRONT AND SOME VERY MILD PACIFIC AIR...AS EVIDENCED BY 50 DEGREE TEMPERATURES AS CLOSE AS SIOUX CITY...IA. EVEN OUT IN WRN MN WHERE THE SKIES HAVE CLEARED OUT...TEMPERATURES HAVE MANAGED TO PUSH UP INTO THE MID/UPPER 30S. THIS MILD AIRMASS WILL BE WITH US THROUGH THE REST OF THE SHORT TERM. CONSIDERING MSP HAS NOT HAD A DAY WITH AN AVERAGE TEMPERATURE ABOVE NORMAL SINCE JAN 24TH...I`M SURE SOME WARMER TEMPERATURES WILL BE WELL RECEIVED! WITH GENERAL SLOWING OF THE SYSTEM...HAVE HAD TO SLOW DOWN EASTWARD MOVEMENT OF CLEARING AND ENDING OF SNOW IN GRIDS. SNOW LIKELY WILL NOT CLEAR WRN WISCONSIN UNTIL 00Z...BUT HAVE DECIDED TO NOT EXTEND THE WARNING BEYOND 3 PM. THIS IS BECAUSE VISIBILITY RESTRICTIONS HAVE MAINLY COME UP TO 2 OR MORE MILES...WHICH MEANS THE RATES HAVE REALLY LET UP. AT THIS POINT...ANY REMAINING SNOWS WILL BE LIGHT WITH ACCUMULATIONS UP TO AN INCH. THIS WILL BRING SNOW TOTALS IN WISCONSIN UP TO AROUND 4 INCHES...WHICH COMBINED WITH THE LIGHTER INTENSITY DOES NOT REALLY JUSTIFY KEEPING THE WARNING GOING...EVEN IF LIGHT SNOW BLEEDS TO 00Z. FOR HIGHS TOMORROW...ONLY GUIDANCE THAT WAS AVOIDED AT THIS POINT WAS THE SREF/NAM/GFS. THIS IS BECAUSE THESE MODELS CONTINUE TO OVER COOL THE BOUNDARY LAYER DUE TO THE SNOW COVER. INSTEAD...CONTINUED TO TREND THINGS TOWARD THE WARMER NCEP MOS GUIDANCE AND NON-NCEP RAW MODEL OUTPUT. THIS CONTINUES THE MENTION OF UPPER 30S TO LOWER 40S...THOUGH WITH THE EDGE OF THE SNOWPACK SO CLOSE...WOULD NOT BE SURPRISED IF THESE TEMPERATURES ENDED UP BEING ABOUT 5 DEGREES TOO COLD...ESPECIALLY OUT SW OF THE MN RIVER. IF A HIGH OF 40 CAN BE ACHIEVED...IT WOULD BE THE FIRST TIME SINCE JANUARY 12TH AT MSP AND EAU CLAIRE AND DECEMBER 27TH FOR ST. CLOUD. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 245 PM CST MON FEB 17 2014 LONG TERM TRENDS CONTINUE TO INDICATE A WARM PERIOD INTO MIDWEEK BEFORE THE NEXT SIGNIFICANT TROUGH DROPS INTO THE MIDSECTION OF THE COUNTRY...WITH CYCLOGENESIS OVER KANSAS/OKLAHOMA REGION... LIFTING NORTHEAST AND OCCLUDING OVER EASTERN WISCONSIN BY THURSDAY EVENING. FOLLOWING THIS WILL BE ANOTHER SHOT OF COLD AIR THROUGH THE REMAINDER OF THE WEEK AND INTO NEXT WEEK AS THE EASTERN CONUS TROUGH REDEVELOPS. THE PRESENT FORECAST TRACK OF THE NEXT SURFACE LOW WILL SPREAD A DECENT SWATH OF SNOW BACK INTO OUR CWA THURSDAY. THE 12Z DETERMINISTIC GFS AND ECMWF BOTH INDICATE THE SURFACE LOW TRACKING OVER EASTERN WISCONSIN THURSDAY. WEST CENTRAL WISCONSIN HAS THE BEST SHOT OF 4 INCHES OR MORE OF SNOW WITH THIS SYSTEM. WE HAVE EXTENDED THE LIKELY POPS EXTEND INTO EAST CENTRAL INTO SOUTH CENTRAL MINNESOTA...WITH LESSER SNOW AMOUNTS AMOUNTS EXPECTED HERE. PTYPE ISSUES RETURN AS WARMER AIR IS LIFTED NORTH AND EAST OF THE INITIAL TROUGH FOR WEDNESDAY. APPEARS TO BE A RAIN...SLEET...SNOW MIX POSSIBLE DEVELOPING LATER WEDNESDAY NIGHT OVER THE REGION. DID INCLUDE THIS MIXED PRECIPITATION POSSIBILITY INTO EARLY THURSDAY. AS THE LOW SHIFTS EAST THURSDAY...COLDER AIR WILL DROP INTO THE AREA AND TRANSITION ANY MIX OVER TO SNOW. COOLER TEMPERATURES FOLLOW THIS SYSTEM WITH HIGHS DROPPING BACK INTO THE TEENS THROUGH THE WEEKEND. WILL COULD SEE SOME MORE BELOW ZERO LOWS ACROSS MUCH OF THE AREA BY EARLY NEXT WEEK. THE 12Z ECMWF DROPS A LARGE ARCTIC 1042MB HIGH SOUTHEAST OVER THE EASTERN CONUS LATE IN THE WEEKEND. THE 12Z ECMWF SHOWS H85 TEMPERATURES DROPPING BACK TO MINUS 32C OVER THE GREAT LAKES BY NEXT TUESDAY NIGHT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1148 AM CST MON FEB 17 2014 MAIN CHANGE WITH THESE TAFS WAS TO DELAY THE RETURN OF VFR CONDITIONS THIS AFTERNOON/EVENING AS THE SYSTEM MOVING THROUGH IS BEGINNING TO TAKE ON MORE OF A NORTHWESTWARD TILT...WHICH HAS ALLOWED EVERYTHING TO SLOW DOWN A BIT. BASED TIMING OF THE RETURN TO VFR ON THE RAP...THOUGH TIMING ERRORS OF ABOUT +/- 1 HOUR CAN BE EXPECTED. TONIGHT INTO TUESDAY MORNING...NEXT TROUGH MOVES THROUGH WHICH WILL BRING NOTHING MORE THAN INCREASED MID LEVEL CLOUDS. BESIDE THE CLOUDS THIS TROUGH WILL LEAD TO A DECENT AMOUNT IN TURNING WITH WINDS...THOUGH MODEL AGREEMENT ON WIND DIRECTION IS GOOD. KMSP...HRRR HAS HAD A GOOD HANDEL ON THE BACK EDGE OF THE SNOW THIS MORNING...THOUGH RADAR CURRENTLY SHOWS REFLECTIVITY STARTING TO FILL BACK IN TO OUR WEST...SO WE MAY NOT COMPLETELY RID THE AIR OF SNOWFLAKES UNTIL THE LOWER CLOUDS CLEAR OUT. CONFIDENCE LOWER ON GOING BACK TO VFR...BUT BASED ON CURRENT TRENDS...THE SLOWER PLAY OF THE RAP IS PROBABLY A GOOD START. CONFIDENCE HIGH IN REMAINDER OF TAF FOR TONIGHT/TUESDAY. /OUTLOOK FOR KMSP/ WED...VFR. WIND WSW EARLY...BCMG SSE 5-15 KT. THU...MVFR OR LOWER WITH SN LIKELY. WIND WNW 10-15KT. FRI...VFR. WINDS NW 5-10KT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MPG LONG TERM...DWE AVIATION...MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1214 PM CST MON FEB 17 2014 .UPDATE... ISSUED AT 1148 AM CST MON FEB 17 2014 SNOW IS BEGINNING TO WIND DOWN ACROSS MN AND MOVE INTO WI...THOUGH RATES HAVE STARTED TO COME DOWN AS EVIDENCED BY THE LACK OF OBSERVATIONS WITH VISIBILITIES UNDER 1SM. THOUGH SNOW IS MOVING OUT A BIT SLOWER...NO EXTENSIONS IN TIME WITH THE WARNING ARE PLANNED AS THE BRUNT OF THE ACCUMULATING SNOWS WILL BE DOWN BY 18Z IN MN AND 20Z IN WI. 18Z AVIATION DISCUSSION ADDED BELOW. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 410 AM CST MON FEB 17 2014 ONLY MINOR TWEAKS WERE MADE TO THE SHORT TERM PERIOD OF THE FORECAST. THE SNOW EVENT IS COMMENCING ACROSS CENTRAL AND SOUTH CENTRAL MN...DRIVEN BY A HEALTHY MID/UPPER TROUGH EJECTING FROM THE NORTHERN PLAINS TOWARD THE GREAT LAKES. WHILE THE DURATION OF THE FORCING AND ATTENDANT SNOWFALL WILL BE RATHER SHORT /3-4 HOURS/...THE INTENSE NATURE OF SAID FORCING SHOULD SUPPLY HOURLY ACCUMULATIONS IN THE 1-1.5 INCH RANGE...KEEPING SNOWFALL TOTALS IN CHECK WITH PRIOR FORECASTS /GENERALLY 3-7 INCHES ACROSS THE CWA/. WINDS HAVE BEEN A BIT STRONGER THAN PREVIOUSLY EXPECTED...SO HAVE HIT THE MENTION OF BLOWING SNOW A BIT HARDER. SNOW TAPERS FROM WEST TO EAST DURING THE LATE MORNING AND AFTERNOON...WITH MOST LOCATIONS SNOWFALL-FREE BY 00Z TUESDAY. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 410 AM CST MON FEB 17 2014 MILD WX WILL OCCUR IN THE WAKE OF TODAY/S SYSTEM AS MORE PACIFIC AIR RIDES OVER THE ROCKIES AND INTO THE UPPER MIDWEST. 30S AND A FEW 40S WILL LIKELY OCCUR ACROSS THE AREA TUE/WED. ONLY MINOR DIFFERENCES IN SFC TEMPS FROM PREVIOUS FORECAST. THIS IS BASED ON MODELS CORRELATION TO SNOW DEPTH AND AMT OF SUNLIGHT. THERE REMAINS SOME UNCERTAINTY FOR WED NIGHT/THURSDAY SYSTEM WHICH TAKES THE SFC LOW A FEW HUNDRED MILES TO THE NW FROM PREVIOUS MODEL RUNS. THIS IS BASED ON THE SLOWER MOVEMENT OF THE LONG WAVE TROUGH ACROSS THE ROCKIES AND A STRONGER JET STREAM ACROSS THE CENTRAL U.S. THIS WILL MAKE FOR A POSSIBLE SNOW STORM ALONG THE N/NW SIDE OF THE SFC LOW TRACK...BUT ALL THE RIGHT ELEMENTS MUST COME TOGETHER. AT THIS TIME...BASED ON THICKNESS VALUES...TIMING AND STRENGTH OF THE UPPER JET...WILL CONTINUE WITH A CHANCE OF A MIXTURE OF FREEZING RAIN/RAIN OR SNOW BEFORE WE GET A BETTER IDEA ONCE IT MOVES INTO THE ROCKIES BY TUE. THE FORECAST FOR THE UPCOMING WEEKEND REMAINS COLD AS PREVIOUS FORECAST INDICATED. ONCE THE PATTERN CHGS WITH A BROAD LONG WAVE TROUGH REESTABLISHES ACROSS THE CENTRAL/EASTERN U.S....THE ARCTIC AIR FROM CANADA WILL ONCE AGAIN COMMENCE OVER OUR REGION. THE COLD PATTERN LOOKS TO HOLD AT LEAST THROUGH EARLY NEXT WEEK. NO MAJOR STORM SYSTEMS EXPECTED ONCE THE WED/THU SYSTEM MOVES THROUGH. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1148 AM CST MON FEB 17 2014 MAIN CHANGE WITH THESE TAFS WAS TO DELAY THE RETURN OF VFR CONDITIONS THIS AFTERNOON/EVENING AS THE SYSTEM MOVING THROUGH IS BEGINNING TO TAKE ON MORE OF A NORTHWESTWARD TILT...WHICH HAS ALLOWED EVERYTHING TO SLOW DOWN A BIT. BASED TIMING OF THE RETURN TO VFR ON THE RAP...THOUGH TIMING ERRORS OF ABOUT +/- 1 HOUR CAN BE EXPECTED. TONIGHT INTO TUESDAY MORNING...NEXT TROUGH MOVES THROUGH WHICH WILL BRING NOTHING MORE THAN INCREASED MID LEVEL CLOUDS. BESIDE THE CLOUDS THIS TROUGH WILL LEAD TO A DECENT AMOUNT IN TURNING WITH WINDS...THOUGH MODEL AGREEMENT ON WIND DIRECTION IS GOOD. KMSP...HRRR HAS HAD A GOOD HANDEL ON THE BACK EDGE OF THE SNOW THIS MORNING...THOUGH RADAR CURRENTLY SHOWS REFLECTIVITY STARTING TO FILL BACK IN TO OUR WEST...SO WE MAY NOT COMPLETELY RID THE AIR OF SNOWFLAKES UNTIL THE LOWER CLOUDS CLEAR OUT. CONFIDENCE LOWER ON GOING BACK TO VFR...BUT BASED ON CURRENT TRENDS...THE SLOWER PLAY OF THE RAP IS PROBABLY A GOOD START. CONFIDENCE HIGH IN REMAINDER OF TAF FOR TONIGHT/TUESDAY. /OUTLOOK FOR KMSP/ WED...VFR. WIND WSW EARLY...BCMG SSE 5-15 KT. THU...MVFR OR LOWER WITH SN LIKELY. WIND WNW 10-15KT. FRI...VFR. WINDS NW 5-10KT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WARNING UNTIL NOON CST TODAY FOR MNZ051>053-059>063- 068>070-077-078. WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MNZ043>045-050- 085-093. WI...WINTER STORM WARNING UNTIL 3 PM CST THIS AFTERNOON FOR WIZ014>016-023>028. && $$ UPDATE...MPG SHORT TERM...LS LONG TERM...JLT AVIATION...MPG
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1210 PM CST Mon Feb 17 2014 .UPDATE... Issued at 1207 PM CST MON FEB 17 2014 The last of the snow and sleet has exited the CWA and clear skies have replaced the clouds. Gusty west-northwest winds with pronounced downslope component is allowing temperatures to warm quickly...and ahead of early forecasts. Have raised high temperatures by 3-5F for all but the far eastern counties. UPDATE Issued at 644 AM CST MON FEB 17 2014 Precipitation is rapidly clearing out from west to east so the threat for significant snow and ice is decreasing. Additional icing will be confined to the Moberly/Macon/Kirksville areas and should just be a few hundredths of an inch. Band of light precipitation swinging through far northern MO near Maryville and Bethany is a mix of snow, sleet and rain/freezing rain and will produce very minor snow accumulations less than an inch. It`s possible that precipitation could fill in a bit more over far northern MO over the next few hours and produce up to an inch of snow near Milan and Kirksville. Will continue to remove counties from the advisories as needed as temperatures rise above freezing and precipitation tapers off from west to east. && .DISCUSSION... Issued at 346 AM CST MON FEB 17 2014 Freezing rain is blossoming across central and northern MO early this morning in an area of deep isentropic ascent and increasing moisture. The freezing line has been able to lift a tad further north than what was forecast and currently stretches from just north of St. Joseph to near Chillicothe and just north of Boonville. Temperatures are expected to remain above freezing for the remainder of the day for areas south of this line so the freezing rain advisory will be adjusted to remove a few counties near St. Joe. Further north and east, concern is growing that ice totals may be a bit higher than previously forecast for the Kirksville, Milan and Macon areas. Both the RAP and HRRR have been persistent in producing QPF amounts around a half inch for these areas through mid-morning, most of which would fall as freezing rain. If these amounts were to verify, several counties across northern and northeast Missouri would see ice accumulations between a quarter of an inch and a half inch which would push them into ice storm warning criteria. However, both of these models have been initializing with precipitation too far west near Kansas City where radar echoes have been slow to develop. Isentropic ascent is currently maximized near and east of the US 65 corridor which is where most of the precipitation is, with only weak ascent if not downglide starting to push into western MO. This downglide is forecast to increase through the morning so that precipitation may struggle to intensify over western MO, causing the RAP and HRRR precipitation forecasts to be too high. Will therefore stick with ice totals of a quarter inch or less for northeastern portions of the forecast area. However this area will be watched very closely in case precipitation does expand further west and leads to more ice accumulation than what is currently forecast. Colder air will filter in aloft after 8 am and cause precipitation over northern MO to mix with sleet and snow. Snow and sleet accumulations up to an inch are possible mainly north of a Maryville to Kirksville line. Any sleet and snow should be fairly short lived as isentropic downglide will really increase after 15Z and bring precipitation to a rapid end by noon. The main story behind this system will be rising temperatures with westerly downslope flow bringing temperatures into the middle and upper 50s for most areas on Tuesday. The next weather maker will arrive Wednesday night and Thursday when a surface low will track from southern Kansas into central and northeast Missouri. Rain will overspread the area ahead of this system Wednesday night and Thursday morning and there could be a few thunderstorms near and south of the surface low track. Quasi-zonal upper flow behind this system will keep temperatures several degrees above average through Friday. Models continue to advertise a weak system moving into the area over the weekend with the potential for light wintry precipitation. Higher preference was placed on the more consistent GFS solution which would keep any precipitation amounts fairly light. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon) Issued at 1125 AM CST MON FEB 17 2014 Skies have rapidly cleared across western MO this morning and will remain clear for this forecast. Back edge of snow has pushed into far northeast MO and will exit there shortly. Strong northwest winds aloft have mixed down to the surface so gusty winds will continue until late afternoon. Impressive looking inversion expected to form within the boundary layer later this evening. Southwesterly winds will ramp up just above this inversion resulting in LLWS concerns by the pre-dawn hours of Tuesday morning. Once inversion begins to break down by mid-morning winds will become gusty rapidly. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ UPDATE...MJ DISCUSSION...Hawblitzel AVIATION...MJ
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1131 AM CST Mon Feb 17 2014 .UPDATE... Issued at 644 AM CST MON FEB 17 2014 Precipitation is rapidly clearing out from west to east so the threat for significant snow and ice is decreasing. Additional icing will be confined to the Moberly/Macon/Kirksville areas and should just be a few hundredths of an inch. Band of light precipitation swinging through far northern MO near Maryville and Bethany is a mix of snow, sleet and rain/freezing rain and will produce very minor snow accumulations less than an inch. It`s possible that precipitation could fill in a bit more over far northern MO over the next few hours and produce up to an inch of snow near Milan and Kirksville. Will continue to remove counties from the advisories as needed as temperatures rise above freezing and precipitation tapers off from west to east. && .DISCUSSION... Issued at 346 AM CST MON FEB 17 2014 Freezing rain is blossoming across central and northern MO early this morning in an area of deep isentropic ascent and increasing moisture. The freezing line has been able to lift a tad further north than what was forecast and currently stretches from just north of St. Joseph to near Chillicothe and just north of Boonville. Temperatures are expected to remain above freezing for the remainder of the day for areas south of this line so the freezing rain advisory will be adjusted to remove a few counties near St. Joe. Further north and east, concern is growing that ice totals may be a bit higher than previously forecast for the Kirksville, Milan and Macon areas. Both the RAP and HRRR have been persistent in producing QPF amounts around a half inch for these areas through mid-morning, most of which would fall as freezing rain. If these amounts were to verify, several counties across northern and northeast Missouri would see ice accumulations between a quarter of an inch and a half inch which would push them into ice storm warning criteria. However, both of these models have been initializing with precipitation too far west near Kansas City where radar echoes have been slow to develop. Isentropic ascent is currently maximized near and east of the US 65 corridor which is where most of the precipitation is, with only weak ascent if not downglide starting to push into western MO. This downglide is forecast to increase through the morning so that precipitation may struggle to intensify over western MO, causing the RAP and HRRR precipitation forecasts to be too high. Will therefore stick with ice totals of a quarter inch or less for northeastern portions of the forecast area. However this area will be watched very closely in case precipitation does expand further west and leads to more ice accumulation than what is currently forecast. Colder air will filter in aloft after 8 am and cause precipitation over northern MO to mix with sleet and snow. Snow and sleet accumulations up to an inch are possible mainly north of a Maryville to Kirksville line. Any sleet and snow should be fairly short lived as isentropic downglide will really increase after 15Z and bring precipitation to a rapid end by noon. The main story behind this system will be rising temperatures with westerly downslope flow bringing temperatures into the middle and upper 50s for most areas on Tuesday. The next weather maker will arrive Wednesday night and Thursday when a surface low will track from southern Kansas into central and northeast Missouri. Rain will overspread the area ahead of this system Wednesday night and Thursday morning and there could be a few thunderstorms near and south of the surface low track. Quasi-zonal upper flow behind this system will keep temperatures several degrees above average through Friday. Models continue to advertise a weak system moving into the area over the weekend with the potential for light wintry precipitation. Higher preference was placed on the more consistent GFS solution which would keep any precipitation amounts fairly light. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon) Issued at 1125 AM CST MON FEB 17 2014 Skies have rapidly cleared across western MO this morning and will remain clear for this forecast. Back edge of snow has pushed into far northeast MO and will exit there shortly. Strong northwest winds aloft have mixed down to the surface so gusty winds will continue until late afternoon. Impressive looking inversion expected to form within the boundary layer later this evening. Southwesterly winds will ramp up just above this inversion resulting in LLWS concerns by the pre-dawn hours of Tuesday morning. Once inversion begins to break down by mid-morning winds will become gusty rapidly. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...FREEZING RAIN ADVISORY until Noon CST today FOR MOZ024-025-032- 033. WINTER WEATHER ADVISORY until Noon CST today FOR MOZ007-008-016- 017. && $$ UPDATE...Hawblitzel DISCUSSION...Hawblitzel AVIATION...MJ
AREA FORECAST DISCUSSION
NWS BILLINGS MT
1048 AM MST MON FEB 17 2014 .UPDATE... HAVE ADDED WHEATLAND COUNTY TO THE HIGH WIND WARNING AS JUDITH GAP RECENTLY GUSTED TO THE MID 50S...WITH PEAK WINDS EXPECTED LATER TODAY. NO OTHER CHANGES AT THIS TIME. JKL PREVIOUS DISCUSSION ISSUED 904 AM... CONDITIONS HAVE BECOME A BIT MORE FAVORABLE FOR WINDS AT LIVINGSTON THIS MORNING...WITH A BACKED GRADIENT DUE TO WESTERN AND CENTRAL MT PRESSURE FALLS...AND WINDS HAVE INCREASED AS A RESULT HERE AND DECREASED AT SUCH PLACES AS BIG TIMBER...HARLOWTON AND JUDITH GAP. ONSET OF COLD ADVECTION AND DESTABILIZING WILL ALLOW FOR WINDS TO INCREASE AGAIN THRU SWEET GRASS AND WHEATLAND COUNTIES THIS AFTERNOON...SO THE CURRENT LULL IS ONLY TEMPORARY. AM A BIT CONCERNED THAT GUSTS COULD PUSH 60 MPH IN WHEATLAND COUNTY LATER TODAY WITH MIXING BUT THERE ARE A COUPLE FACTORS WORKING AGAINST THIS...PRESSURE FALLS TO OUR SOUTH IN ID/WY AND SOME SYNOPTIC SCALE ASCENT AS SHORTWAVE ENERGY APPROACHES FROM THE WEST. SO WILL KEEP GUSTS LIMITED TO 50-55 MPH AT HARLOWTON AND JUDITH GAP. WINDS WILL REMAIN STRONG THRU TONIGHT. WILL MAKE NO CHANGES TO THE WIND HIGHLIGHTS FOR LIVINGSTON...NYE AND BIG TIMBER. SURPRISE SURPRISE ANOTHER WINDY DAY FOLKS. THERE IS QUITE A BIT OF WIND FLOW OVER THE CREST OF THE BIG HORNS THIS MORNING AND BURGESS JCT WINDS WERE GUSTING NEAR 50 MPH AT 8 AM. RAP SUGGESTS THAT THRU MIXING SHERIDAN WILL SEE INCREASED WSW GUSTS LATER THIS MORNING...BUT FEEL THAT WITHOUT STRONGER DESCENT WE WILL NOT SEE THAT DEGREE OF WIND PUSH DOWN THE LEE OF THE MTNS. THAT BEING SAID WILL NEED TO WATCH THE SHERIDAN AREA TODAY AND HAVE RAISED WIND SPEEDS TO SHOW GUSTS TO 30 MPH TODAY. OTHER THAN WIND THERE ARE NO OTHER FORECAST ISSUES TODAY. TEMPS WILL RISE TO THE 40S OR LOW 50S WITH PERSISTENT DOWNSLOPE CONDITIONS AND A FRONTAL PASSAGE LATE. SNOW SHOWERS WILL INCREASE OVER THE WEST SLOPES AFTER 00Z. JKL && .SHORT TERM...VALID FOR TDY AND TUE... UPPER JET ENERGY WILL CONTINUE TO MOVE ACROSS THE AREA CREATING A FAST WESTERLY FLOW THROUGH THE FORECAST PERIOD. ENSEMBLE SITUATIONAL AWARENESS TABLE CONTINUED TO HIGHLIGHT ANOMALOUSLY HIGH MID LEVEL WINDS WITH SOME ANOMALIES SHOWING UP AT 850 MB AS WELL. FORECAST CHALLENGE CONTINUES TO BE HOW MUCH WIND WILL REACH THE GROUND. HOWEVER...FOR THIS MORNING IN KLVM...NYE AND BIG TIMBER...THE CAUSATIVE FACTORS FOR WINDS WILL BE GAP FLOW AND IN THE CASE OF BIG TIMBER POSSIBLE MOUNTAIN WAVES. BIG TIMBER/S WIND SPEEDS WERE IN THE 50S EARLY THIS MORNING. THERE WAS DRAINAGE OCCURRING OUT OF THE MAIN BOULDER...AND IR SATELLITE IMAGERY SHOWED WAVE CLOUDS OVER THE AREA. EXPECT THIS SETUP TO CONTINUE DURING THE MORNING HOURS BEFORE MIXING TAKES OVER IN THE AFTERNOON. THUS WILL CONTINUE THE HIGH WIND WARNING FOR THIS AREA. FOR THE GAP FLOW AREAS...WINDS WERE NOT AS STRONG THIS MORNING...AND PRESSURE FALLS WERE BACK OVER W MT. THE GFS AND WRF BROUGHT GOOD PRESSURE FALLS INTO THE KLVM AREA BY 18Z. COUNTING ON THE FALLS TO REORIENT THE PRESSURE GRADIENT TO FAVOR STRONG GAP FLOW WINDS THIS MORNING SO WILL LEAVE HIGH WIND WARNING IN PLACE. REMAINDER OF THE AREA WILL BE BREEZY TO WINDY TODAY...ESPECIALLY THIS AFTERNOON DUE TO MIXING. THE STRONGEST WINDS WILL BE W OF KBIL. SHORTWAVE ENERGY...PACIFIC MOISTURE AND A COLD FRONT WILL APPROACH THE AREA TODAY. MOISTURE COULD BE SEEN IN SATELLITE IMAGERY THIS MORNING. THESE FACTORS WILL BRING A SLIGHT CHANCE OF SNOW SHOWERS TO THE WESTERN MOUNTAINS...OTHERWISE IT WILL BE A PARTLY CLOUDY DAY. MIXDOWNS SUPPORTED TEMPERATURES IN THE 40S TO LOWER 50S. THE WAVE AND FRONT WILL MOVE THROUGH THE AREA TONIGHT BRINGING MOUNTAIN SNOW AND A SLIGHT CHANCE OF RAIN AND SNOW SHOWERS TO THE PLAINS. TIME-HEIGHTS FOR THE SW MOUNTAINS WERE UNSTABLE SO EXPECT A FEW INCHES OF SNOW FOR THE HIGH TERRAIN. THE BREEZY TO WINDY CONDITIONS WILL CONTINUE ACROSS THE AREA BUT DO NOT ANTICIPATE ANY HIGHLIGHTS. THE SYSTEM WILL MOVE OUT OF THE AREA EARLY ON TUE WITH SOME LINGERING PRECIPITATION CHANCES OVER AND NEAR THE MOUNTAINS. IT WILL REMAIN WINDY ON TUE. TEMPERATURES WILL BE SIMILAR TO TODAY/S READINGS. BRIEF UPPER RIDGING WILL BUILD OVER THE AREA TUE AFTERNOON BEFORE ANOTHER SHORTWAVE AND COLD FRONT MOVE INTO THE REGION TUE NIGHT. THERE WILL BE A BAND OF FRONTOGENESIS ALONG THE FRONT BUT NOT A LOT OF MOISTURE OVER THE PLAINS SO LOWERED THE POPS. THE MOUNTAINS WILL HAVE THE BEST CHANCE OF PRECIPITATION. ANOTHER LEE TROUGH WILL PRECEDE THE FRONT TUE NIGHT WHICH WILL BRING INCREASING WINDS TO KLVM. HAVE INCREASED THE WIND SPEEDS FOR THIS PERIOD. WILL HAVE TO SEE IF ANY HIGHLIGHTS WILL BE NEEDED AS ARRIVAL OF FRONT WILL CUT OFF STRONG GAP FLOW WINDS LATE TUE NIGHT. ARTHUR .LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN... WEDNESDAY WILL SEE THE WIND EPISODE CONTINUE AND SPREAD INTO THE PLAINS AS AN EARLY MORNING COLD FRONT IS FOLLOWED BY STRONG MOMENTUM ALOFT AND AN UNSTABLE AIRMASS. DRY AIR ROTATING AROUND AN UPPER LOW IN SASKATCHEWAN WILL LIMIT SHOWER ACTIVITY BUT IT SHOULD PERMIT SOME SUNSHINE WHICH WILL KEEP TEMPERATURES AROUND THE 40 DEGREE MARK AND ALLOW FOR STEEP LOW LEVEL LAPSE RATES SUPPORTING MIXING. AS THE WEDNESDAY SYSTEM MOVES EAST WEDNESDAY NIGHT ANOTHER SURGE OF ENERGY MOVES INTO NORTHWEST MONTANA IN NORTHWEST FLOW ALOFT. SHORTWAVE RIDGING BEHIND THE FIRST SYSTEM SLOWS HEIGHT FALLS OVER THE REGION AND PATTERN BECOMES LESS PROGRESSIVE. INCREASING NORTHWEST FLOW ALOFT CAUSES THE NEXT SURFACE WAVE TO TRANSLATE ACROSS MONTANA AS OPPOSED TO CANADA AND THIS WILL BRING A BETTER CHANCE FOR SNOW WITH COLDER TEMPERATURES MOVING INTO THE AREA. THURSDAY NIGHT AND FRIDAY IS ONE OF THE PERIODS THAT HAS A BETTER CHANCE TO PRODUCE SNOWFALL AS THE COLDEST AIR PUSHES UP AGAINST THE HIGHER TERRAIN AND UPSLOPE WORKS WITH AN UNSTABLE AND MOIST ATMOSPHERE. SURFACE PRESSURE IS NOT OVERLY DEEP AND MIDLEVEL NORTHWEST FLOW CAUSES THE UPSLOPE ORIENTATION TO BE LESS THAN IDEAL SO SIGNIFICANT SNOW IS HARDLY EXPECTED. BUT IT WILL BE A BIG CHANGE FROM THE MILD AND WINDY WEATHER. SATURDAY AND SUNDAY AN UPSTREAM RIDGE BEGINS TO BUILD OVER THE PACIFIC NORTHWEST WHILE THE COLDER AIR IS REINFORCED OVER EASTERN MONTANA BY NORTHWEST FLOW ALOFT. A BAND OF ISENTROPIC/FRONTOGENIC PRECIPITATION IS EXPECTED OVER THE CENTRAL AND EASTERN ZONES WITH THE WESTERN ZONES BEGINNING TO SEE KLONDIKE CHINOOK CONDITIONS. MONDAY THE PATTERN BREAKS DOWN AS THE ENERGY MOVING ACROSS THE CANADIAN ROCKIES DISPLACES THE COLD AIR FURTHER EAST. THIS WILL BRING MODERATING TEMPERATURES AND DECREASE CHANCES FOR SNOW. AND POSSIBLY MORE WIND FOR GAP FLOW AREAS. TEMPERATURES WILL BE COLDEST FRIDAY NIGHT THROUGH SUNDAY WITH HIGHS 30 OR LOWER AND MINIMUMS OF 5 TO 15...ROUGHLY 15 DEGREES BELOW NORMAL. BORSUM && .AVIATION... STRONG AND GUSTY SOUTHWEST TO WEST WINDS ARE EXPECTED TO CONTINUE ALONG THE FOOTHILLS TODAY...WITH GUSTS IN EXCESS OF 50 KNOTS POSSIBLE. OTHERWISE...VFR CONDITIONS ARE EXPECTED TO PREVAIL ACROSS THE REGION...WITH THE EXCEPTION OF SOME MOUNTAIN SHOWER ACTIVITY. THERE IS ALSO A CHANCE FOR SOME ISOLATED SHOWERS THIS EVENING FROM BILLINGS WESTWARD ...WITH LOCALIZED REDUCTIONS IN FLIGHT CONDITIONS POSSIBLE. AAG && .PRELIMINARY POINT TEMP/POPS... TDY TUE WED THU FRI SAT SUN ------------------------------------------------------- BIL 049 030/048 033/044 025/038 020/030 011/027 012/030 1/N 21/N 32/W 12/J 34/J 32/J 22/J LVM 051 029/046 032/043 020/035 017/029 004/025 010/031 1/N 32/J 42/W 23/J 44/J 22/J 22/J HDN 051 029/053 032/046 023/039 018/033 009/029 009/031 1/N 21/N 32/W 12/J 24/J 32/J 22/J MLS 047 027/045 029/044 020/035 017/026 006/022 008/024 0/B 11/B 32/W 12/J 23/J 22/J 12/J 4BQ 052 029/051 029/047 023/039 018/032 008/028 009/029 0/B 21/N 12/W 02/J 24/J 22/J 22/J BHK 045 025/042 023/043 016/033 012/027 002/020 003/022 0/N 10/N 22/W 11/B 23/J 22/J 12/J SHR 052 026/047 028/047 018/039 016/030 005/028 008/031 1/N 21/N 14/W 12/J 34/J 42/J 32/J && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...HIGH WIND WARNING IN EFFECT UNTIL 6 PM MST THIS EVENING FOR ZONES 28-41-63-65-66. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BILLINGS MT
904 AM MST MON FEB 17 2014 .UPDATE... CONDITIONS HAVE BECOME A BIT MORE FAVORABLE FOR WINDS AT LIVINGSTON THIS MORNING...WITH A BACKED GRADIENT DUE TO WESTERN AND CENTRAL MT PRESSURE FALLS...AND WINDS HAVE INCREASED AS A RESULT HERE AND DECREASED AT SUCH PLACES AS BIG TIMBER...HARLOWTON AND JUDITH GAP. ONSET OF COLD ADVECTION AND DESTABILIZING WILL ALLOW FOR WINDS TO INCREASE AGAIN THRU SWEET GRASS AND WHEATLAND COUNTIES THIS AFTERNOON...SO THE CURRENT LULL IS ONLY TEMPORARY. AM A BIT CONCERNED THAT GUSTS COULD PUSH 60 MPH IN WHEATLAND COUNTY LATER TODAY WITH MIXING BUT THERE ARE A COUPLE FACTORS WORKING AGAINST THIS...PRESSURE FALLS TO OUR SOUTH IN ID/WY AND SOME SYNOPTIC SCALE ASCENT AS SHORTWAVE ENERGY APPROACHES FROM THE WEST. SO WILL KEEP GUSTS LIMITED TO 50-55 MPH AT HARLOWTON AND JUDITH GAP. WINDS WILL REMAIN STRONG THRU TONIGHT. WILL MAKE NO CHANGES TO THE WIND HIGHLIGHTS FOR LIVINGSTON...NYE AND BIG TIMBER. SURPRISE SURPRISE ANOTHER WINDY DAY FOLKS. THERE IS QUITE A BIT OF WIND FLOW OVER THE CREST OF THE BIG HORNS THIS MORNING AND BURGESS JCT WINDS WERE GUSTING NEAR 50 MPH AT 8 AM. RAP SUGGESTS THAT THRU MIXING SHERIDAN WILL SEE INCREASED WSW GUSTS LATER THIS MORNING...BUT FEEL THAT WITHOUT STRONGER DESCENT WE WILL NOT SEE THAT DEGREE OF WIND PUSH DOWN THE LEE OF THE MTNS. THAT BEING SAID WILL NEED TO WATCH THE SHERIDAN AREA TODAY AND HAVE RAISED WIND SPEEDS TO SHOW GUSTS TO 30 MPH TODAY. OTHER THAN WIND THERE ARE NO OTHER FORECAST ISSUES TODAY. TEMPS WILL RISE TO THE 40S OR LOW 50S WITH PERSISTENT DOWNSLOPE CONDITIONS AND A FRONTAL PASSAGE LATE. SNOW SHOWERS WILL INCREASE OVER THE WEST SLOPES AFTER 00Z. JKL && .SHORT TERM...VALID FOR TDY AND TUE... UPPER JET ENERGY WILL CONTINUE TO MOVE ACROSS THE AREA CREATING A FAST WESTERLY FLOW THROUGH THE FORECAST PERIOD. ENSEMBLE SITUATIONAL AWARENESS TABLE CONTINUED TO HIGHLIGHT ANOMALOUSLY HIGH MID LEVEL WINDS WITH SOME ANOMALIES SHOWING UP AT 850 MB AS WELL. FORECAST CHALLENGE CONTINUES TO BE HOW MUCH WIND WILL REACH THE GROUND. HOWEVER...FOR THIS MORNING IN KLVM...NYE AND BIG TIMBER...THE CAUSATIVE FACTORS FOR WINDS WILL BE GAP FLOW AND IN THE CASE OF BIG TIMBER POSSIBLE MOUNTAIN WAVES. BIG TIMBER/S WIND SPEEDS WERE IN THE 50S EARLY THIS MORNING. THERE WAS DRAINAGE OCCURRING OUT OF THE MAIN BOULDER...AND IR SATELLITE IMAGERY SHOWED WAVE CLOUDS OVER THE AREA. EXPECT THIS SETUP TO CONTINUE DURING THE MORNING HOURS BEFORE MIXING TAKES OVER IN THE AFTERNOON. THUS WILL CONTINUE THE HIGH WIND WARNING FOR THIS AREA. FOR THE GAP FLOW AREAS...WINDS WERE NOT AS STRONG THIS MORNING...AND PRESSURE FALLS WERE BACK OVER W MT. THE GFS AND WRF BROUGHT GOOD PRESSURE FALLS INTO THE KLVM AREA BY 18Z. COUNTING ON THE FALLS TO REORIENT THE PRESSURE GRADIENT TO FAVOR STRONG GAP FLOW WINDS THIS MORNING SO WILL LEAVE HIGH WIND WARNING IN PLACE. REMAINDER OF THE AREA WILL BE BREEZY TO WINDY TODAY...ESPECIALLY THIS AFTERNOON DUE TO MIXING. THE STRONGEST WINDS WILL BE W OF KBIL. SHORTWAVE ENERGY...PACIFIC MOISTURE AND A COLD FRONT WILL APPROACH THE AREA TODAY. MOISTURE COULD BE SEEN IN SATELLITE IMAGERY THIS MORNING. THESE FACTORS WILL BRING A SLIGHT CHANCE OF SNOW SHOWERS TO THE WESTERN MOUNTAINS...OTHERWISE IT WILL BE A PARTLY CLOUDY DAY. MIXDOWNS SUPPORTED TEMPERATURES IN THE 40S TO LOWER 50S. THE WAVE AND FRONT WILL MOVE THROUGH THE AREA TONIGHT BRINGING MOUNTAIN SNOW AND A SLIGHT CHANCE OF RAIN AND SNOW SHOWERS TO THE PLAINS. TIME-HEIGHTS FOR THE SW MOUNTAINS WERE UNSTABLE SO EXPECT A FEW INCHES OF SNOW FOR THE HIGH TERRAIN. THE BREEZY TO WINDY CONDITIONS WILL CONTINUE ACROSS THE AREA BUT DO NOT ANTICIPATE ANY HIGHLIGHTS. THE SYSTEM WILL MOVE OUT OF THE AREA EARLY ON TUE WITH SOME LINGERING PRECIPITATION CHANCES OVER AND NEAR THE MOUNTAINS. IT WILL REMAIN WINDY ON TUE. TEMPERATURES WILL BE SIMILAR TO TODAY/S READINGS. BRIEF UPPER RIDGING WILL BUILD OVER THE AREA TUE AFTERNOON BEFORE ANOTHER SHORTWAVE AND COLD FRONT MOVE INTO THE REGION TUE NIGHT. THERE WILL BE A BAND OF FRONTOGENESIS ALONG THE FRONT BUT NOT A LOT OF MOISTURE OVER THE PLAINS SO LOWERED THE POPS. THE MOUNTAINS WILL HAVE THE BEST CHANCE OF PRECIPITATION. ANOTHER LEE TROUGH WILL PRECEDE THE FRONT TUE NIGHT WHICH WILL BRING INCREASING WINDS TO KLVM. HAVE INCREASED THE WIND SPEEDS FOR THIS PERIOD. WILL HAVE TO SEE IF ANY HIGHLIGHTS WILL BE NEEDED AS ARRIVAL OF FRONT WILL CUT OFF STRONG GAP FLOW WINDS LATE TUE NIGHT. ARTHUR .LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN... WEDNESDAY WILL SEE THE WIND EPISODE CONTINUE AND SPREAD INTO THE PLAINS AS AN EARLY MORNING COLD FRONT IS FOLLOWED BY STRONG MOMENTUM ALOFT AND AN UNSTABLE AIRMASS. DRY AIR ROTATING AROUND AN UPPER LOW IN SASKATCHEWAN WILL LIMIT SHOWER ACTIVITY BUT IT SHOULD PERMIT SOME SUNSHINE WHICH WILL KEEP TEMPERATURES AROUND THE 40 DEGREE MARK AND ALLOW FOR STEEP LOW LEVEL LAPSE RATES SUPPORTING MIXING. AS THE WEDNESDAY SYSTEM MOVES EAST WEDNESDAY NIGHT ANOTHER SURGE OF ENERGY MOVES INTO NORTHWEST MONTANA IN NORTHWEST FLOW ALOFT. SHORTWAVE RIDGING BEHIND THE FIRST SYSTEM SLOWS HEIGHT FALLS OVER THE REGION AND PATTERN BECOMES LESS PROGRESSIVE. INCREASING NORTHWEST FLOW ALOFT CAUSES THE NEXT SURFACE WAVE TO TRANSLATE ACROSS MONTANA AS OPPOSED TO CANADA AND THIS WILL BRING A BETTER CHANCE FOR SNOW WITH COLDER TEMPERATURES MOVING INTO THE AREA. THURSDAY NIGHT AND FRIDAY IS ONE OF THE PERIODS THAT HAS A BETTER CHANCE TO PRODUCE SNOWFALL AS THE COLDEST AIR PUSHES UP AGAINST THE HIGHER TERRAIN AND UPSLOPE WORKS WITH AN UNSTABLE AND MOIST ATMOSPHERE. SURFACE PRESSURE IS NOT OVERLY DEEP AND MIDLEVEL NORTHWEST FLOW CAUSES THE UPSLOPE ORIENTATION TO BE LESS THAN IDEAL SO SIGNIFICANT SNOW IS HARDLY EXPECTED. BUT IT WILL BE A BIG CHANGE FROM THE MILD AND WINDY WEATHER. SATURDAY AND SUNDAY AN UPSTREAM RIDGE BEGINS TO BUILD OVER THE PACIFIC NORTHWEST WHILE THE COLDER AIR IS REINFORCED OVER EASTERN MONTANA BY NORTHWEST FLOW ALOFT. A BAND OF ISENTROPIC/FRONTOGENIC PRECIPITATION IS EXPECTED OVER THE CENTRAL AND EASTERN ZONES WITH THE WESTERN ZONES BEGINNING TO SEE KLONDIKE CHINOOK CONDITIONS. MONDAY THE PATTERN BREAKS DOWN AS THE ENERGY MOVING ACROSS THE CANADIAN ROCKIES DISPLACES THE COLD AIR FURTHER EAST. THIS WILL BRING MODERATING TEMPERATURES AND DECREASE CHANCES FOR SNOW. AND POSSIBLY MORE WIND FOR GAP FLOW AREAS. TEMPERATURES WILL BE COLDEST FRIDAY NIGHT THROUGH SUNDAY WITH HIGHS 30 OR LOWER AND MINIMUMS OF 5 TO 15...ROUGHLY 15 DEGREES BELOW NORMAL. BORSUM && .AVIATION... STRONG AND GUSTY SOUTHWEST TO WEST WINDS ARE EXPECTED TO CONTINUE ALONG THE FOOTHILLS TODAY...WITH GUSTS IN EXCESS OF 50 KNOTS POSSIBLE. OTHERWISE...VFR CONDITIONS ARE EXPECTED TO PREVAIL ACROSS THE REGION...WITH THE EXCEPTION OF SOME MOUNTAIN SHOWER ACTIVITY. THERE IS ALSO A CHANCE FOR SOME ISOLATED SHOWERS THIS EVENING FROM BILLINGS WESTWARD ...WITH LOCALIZED REDUCTIONS IN FLIGHT CONDITIONS POSSIBLE. AAG && .PRELIMINARY POINT TEMP/POPS... TDY TUE WED THU FRI SAT SUN ------------------------------------------------------- BIL 049 030/048 033/044 025/038 020/030 011/027 012/030 1/N 21/N 32/W 12/J 34/J 32/J 22/J LVM 051 029/046 032/043 020/035 017/029 004/025 010/031 1/N 32/J 42/W 23/J 44/J 22/J 22/J HDN 051 029/053 032/046 023/039 018/033 009/029 009/031 1/N 21/N 32/W 12/J 24/J 32/J 22/J MLS 047 027/045 029/044 020/035 017/026 006/022 008/024 0/B 11/B 32/W 12/J 23/J 22/J 12/J 4BQ 052 029/051 029/047 023/039 018/032 008/028 009/029 0/B 21/N 12/W 02/J 24/J 22/J 22/J BHK 045 025/042 023/043 016/033 012/027 002/020 003/022 0/N 10/N 22/W 11/B 23/J 22/J 12/J SHR 052 026/047 028/047 018/039 016/030 005/028 008/031 1/N 21/N 14/W 12/J 34/J 42/J 32/J && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...HIGH WIND WARNING IN EFFECT UNTIL 6 PM MST THIS EVENING FOR ZONES 41-65-66. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1240 PM CST MON FEB 17 2014 .UPDATE... CLOUDS HAVE THINNED ACROSS THE SOUTHERN HALF OF THE AREA THIS AFTERNOON AND AS A RESULT TEMPERATURES HAVE BEEN ON THE MARCH UPWARDS. RAISED MAX T GRIDS FOR THE SOUTHERN ZONES. NEW GRIDS OUT SHORTLY. 23 && .PREV DISCUSSION... /ISSUED 1133 AM CST MON FEB 17 2014/ AVIATION... COLD FRONT WILL BE WORKING ITS WAY INTO SE TX THIS AFTERNOON AND WILL STALL SOMEWHERE ACROSS THE AREA. COULD SEE SOME CLEARING BEHIND THE FRONT FOR OUR FAR NORTHERN TAFS...BUT FURTHER TO THE SOUTH EXPECT PERIODS OF MAINLY MVFR CEILINGS THROUGHOUT THE AFTERNOON. AS THE FRONT BEGINS TO MOVE BACK TO THE NORTH TONIGHT...LOW MAINLY MVFR CEILINGS ARE ANTICIPATED ALONG AND SOUTH OF THE BOUNDARY WITH PERIODS OF IFR CEILINGS AND VISIBILITIES POSSIBLE TOO. PERIODS OF IFR/LIFR CEILINGS AND VISIBILITIES POSSIBLE AT GLS DUE TO AREA SEA FOG. 42 PREV DISCUSSION... /ISSUED 1004 AM CST MON FEB 17 2014/ UPDATE... SEE DISCUSSION FOR MORNING UPDATE. DISCUSSION... MOSTLY CLOUDS SKIES ACROSS THE AREA CURRENTLY ALONG WITH SOME DENSE FOG IN THE BAYS. A COLD FRONT HAS JUST MADE IT PAST DFW AND IS EXPECTED TO CONTINUE TO SAG SOUTHWARDS DURING THE AFTERNOON. THIS FRONT IS IN ASSOCIATION WITH A SHORTWAVE CURRENTLY MOVING EAST ACROSS THE MIDWEST. THINKING REMAINS MOSTLY UNCHANGED THAT THE FRONT WILL STALL IN BRAZOS COUNTY WITH A WIND SHIFT POSSIBLE A BIT FURTHER SOUTH. THIS WILL MEAN THAT WARM AND HUMID CONDITIONS WILL PERSIST FOR MUCH OF SOUTHEAST TEXAS TODAY ALONG WITH THE FOG IN THE BAYS. BECAUSE OF THIS HAVE EXTENDED THE DENSE FOG ADVISORY UNTIL NOON TODAY FOR THE BAYS AND NEARSHORE WATERS. THE OTHER CONCERN WILL BE AFTERNOON TEMPERATURES. 850MB TEMPERATURES ARE CURRENTLY AROUND 18C WHICH IS VERY WARM FOR THIS TIME OF YEAR. CLOUDS ALONG WITH SOME 850 COOLING WILL HELP KEEP AFTERNOON TEMPERATURES FROM REALIZING THEIR FULL POTENTIAL BUT IT STILL SHOULD BE WARM. WOULDN`T BE SURPRISED IF SOME PLACES HIT 80 THIS AFTERNOON. MODELS ARE ALSO SHOWING THAT JUST BEHIND THE FRONT THERE WILL BE SOME CLEARING WITH THE COLDER AIR HOLDING BACK SOME. AS OF NOW IT LOOKS LIKE THE CLEARING LINE WILL COME UP JUST SHORT OF KCLL. IF THE CLEARING LINE MAKES IT TO KCLL TEMPERATURES WILL LIKELY QUICKLY RISE AS CAA HOLDS BACK. FOR NOW HAVE JUST BUMPED UP HIGH TEMPERATURES A DEGREE AT KCLL AND A COUPLE OF OTHER PLACES. WILL KEEP AN EYE ON THAT CLEARING LINE AS RAP SHOWS TEMPERATURES AROUND 80 AT HEARNE THIS AFTERNOON. NO OTHER CHANGES PLANNED AT THIS TIME. 23 PREV DISCUSSION... /ISSUED 354 AM CST MON FEB 17 2014/ DISCUSSION... WEAK FRONT WILL MAKE ITS WAY INTO NRN PARTS OF SE TX THIS AFTN THEN STALL SOMEWHERE ALONG A LINE FROM MAYBE COLUMBUS-LIVINGSTON THIS EVENING. THE BOUNDARY WILL HEAD BACK NORTH EARLY TUE. WX SHOULD OTHERWISE BE STATUS QUO THRU EARLY THURS WITH MCLDY WARM CONDITIONS PREVAILING. AND SOME PERIODS OF SEA FOG AT THE COAST. MADE SOME FCST CHANGES LATE THURS & INTO THE WEEKEND. FRONT THAT WAS EARLIER EXPECTED TO STALL INLAND LATE THURS NOW LOOKS LIKE IT SHOULD HAVE MORE THAN ENOUGH SUPPORT TO PUSH WELL OFF THE COAST THURS EVENING. NUDGED POPS UP A TOUCH AS WELL AS PW`S CLIMB TO 1.3-1.5" IN ADVANCE OF THE BOUNDARY. FAVORABLE RRQ JET POSITION & STRONG LLVL JET NOTED...BUT CAP APPEARS LIKE IT MIGHT WIN OUT & LIMIT MUCH CONVECTIVE PRECIP OVER OUR FA. LOWERED TEMPS IN THE WAKE OF THE FRONT AND PULLED MENTION OF SEA FOG W/ ITS PASSAGE AS WELL. SOME DIFFERENCES IN THE MEDIUM RANGE SOLNS THIS WEEKEND AND BEYOND. ECMWF IS QUICK TO BRING A RETURN OF MOISTURE AND PRECIP CHANCES ACROSS SRN PARTS OF THE AREA LATE SAT WHILE GFS BRINGS A WEAK REINFORCING BOUNDARY OFF THE COAST AT THAT TIME. NO REAL CONFIDENCE IN EITHER ONE AT THIS POINT. BOTH DO INDICATE A 1040+MB HIGH SLIDING SWD INTO THE PLAINS NEXT WEEK AND SENDING ASSOCIATED FRONT INTO OUR REGION AROUND 25TH OR 26TH. 47 MARINE... GENERALLY LIGHT/MODERATE ONSHORE WINDS WILL PREVAIL THROUGH MUCH OF THIS WEEK. A WEAK COLD FRONT IS EXPECTED TO MOVE INTO THE NRN PARTS OF SE TX TONIGHT BUT SHOULD STALL BEFORE IT REACHES THE COAST. AS A RESULT...WINDS OVER THE COASTAL WATERS SHOULD REMAIN OUT OF THE SSE. A SECOND STRONGER FRONT IS FCST TO MOVE THROUGH THE AREA LATER THIS WEEK (LIKELY THURS NIGHT/EARLY FRI MORNING). UNTIL THEN SEA FOG MAY BE AN ISSUE FOR THE BAYS/NEARSHORE WATERS AS THE WARMER AIRMASS OV- ERRIDES THE COOLER SHELF WATERS. ONSHORE WINDS COULD GET STRENGTHEN ENOUGH BY WEDS NIGHT/THURS FOR CAUTION FLAGS. 41 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 55 76 61 77 63 / 10 10 10 10 10 HOUSTON (IAH) 60 76 63 77 64 / 10 10 10 10 10 GALVESTON (GLS) 60 69 61 70 63 / 10 10 10 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ DISCUSSION...23
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1133 AM CST MON FEB 17 2014 .AVIATION... COLD FRONT WILL BE WORKING ITS WAY INTO SE TX THIS AFTERNOON AND WILL STALL SOMEWHERE ACROSS THE AREA. COULD SEE SOME CLEARING BEHIND THE FRONT FOR OUR FAR NORTHERN TAFS...BUT FURTHER TO THE SOUTH EXPECT PERIODS OF MAINLY MVFR CEILINGS THROUGHOUT THE AFTERNOON. AS THE FRONT BEGINS TO MOVE BACK TO THE NORTH TONIGHT...LOW MAINLY MVFR CEILINGS ARE ANTICIPATED ALONG AND SOUTH OF THE BOUNDARY WITH PERIODS OF IFR CEILINGS AND VISIBILITIES POSSIBLE TOO. PERIODS OF IFR/LIFR CEILINGS AND VISIBILITIES POSSIBLE AT GLS DUE TO AREA SEA FOG. 42 && .PREV DISCUSSION... /ISSUED 1004 AM CST MON FEB 17 2014/ UPDATE... SEE DISCUSSION FOR MORNING UPDATE. DISCUSSION... MOSTLY CLOUDS SKIES ACROSS THE AREA CURRENTLY ALONG WITH SOME DENSE FOG IN THE BAYS. A COLD FRONT HAS JUST MADE IT PAST DFW AND IS EXPECTED TO CONTINUE TO SAG SOUTHWARDS DURING THE AFTERNOON. THIS FRONT IS IN ASSOCIATION WITH A SHORTWAVE CURRENTLY MOVING EAST ACROSS THE MIDWEST. THINKING REMAINS MOSTLY UNCHANGED THAT THE FRONT WILL STALL IN BRAZOS COUNTY WITH A WIND SHIFT POSSIBLE A BIT FURTHER SOUTH. THIS WILL MEAN THAT WARM AND HUMID CONDITIONS WILL PERSIST FOR MUCH OF SOUTHEAST TEXAS TODAY ALONG WITH THE FOG IN THE BAYS. BECAUSE OF THIS HAVE EXTENDED THE DENSE FOG ADVISORY UNTIL NOON TODAY FOR THE BAYS AND NEARSHORE WATERS. THE OTHER CONCERN WILL BE AFTERNOON TEMPERATURES. 850MB TEMPERATURES ARE CURRENTLY AROUND 18C WHICH IS VERY WARM FOR THIS TIME OF YEAR. CLOUDS ALONG WITH SOME 850 COOLING WILL HELP KEEP AFTERNOON TEMPERATURES FROM REALIZING THEIR FULL POTENTIAL BUT IT STILL SHOULD BE WARM. WOULDN`T BE SURPRISED IF SOME PLACES HIT 80 THIS AFTERNOON. MODELS ARE ALSO SHOWING THAT JUST BEHIND THE FRONT THERE WILL BE SOME CLEARING WITH THE COLDER AIR HOLDING BACK SOME. AS OF NOW IT LOOKS LIKE THE CLEARING LINE WILL COME UP JUST SHORT OF KCLL. IF THE CLEARING LINE MAKES IT TO KCLL TEMPERATURES WILL LIKELY QUICKLY RISE AS CAA HOLDS BACK. FOR NOW HAVE JUST BUMPED UP HIGH TEMPERATURES A DEGREE AT KCLL AND A COUPLE OF OTHER PLACES. WILL KEEP AN EYE ON THAT CLEARING LINE AS RAP SHOWS TEMPERATURES AROUND 80 AT HEARNE THIS AFTERNOON. NO OTHER CHANGES PLANNED AT THIS TIME. 23 PREV DISCUSSION... /ISSUED 354 AM CST MON FEB 17 2014/ DISCUSSION... WEAK FRONT WILL MAKE ITS WAY INTO NRN PARTS OF SE TX THIS AFTN THEN STALL SOMEWHERE ALONG A LINE FROM MAYBE COLUMBUS-LIVINGSTON THIS EVENING. THE BOUNDARY WILL HEAD BACK NORTH EARLY TUE. WX SHOULD OTHERWISE BE STATUS QUO THRU EARLY THURS WITH MCLDY WARM CONDITIONS PREVAILING. AND SOME PERIODS OF SEA FOG AT THE COAST. MADE SOME FCST CHANGES LATE THURS & INTO THE WEEKEND. FRONT THAT WAS EARLIER EXPECTED TO STALL INLAND LATE THURS NOW LOOKS LIKE IT SHOULD HAVE MORE THAN ENOUGH SUPPORT TO PUSH WELL OFF THE COAST THURS EVENING. NUDGED POPS UP A TOUCH AS WELL AS PW`S CLIMB TO 1.3-1.5" IN ADVANCE OF THE BOUNDARY. FAVORABLE RRQ JET POSITION & STRONG LLVL JET NOTED...BUT CAP APPEARS LIKE IT MIGHT WIN OUT & LIMIT MUCH CONVECTIVE PRECIP OVER OUR FA. LOWERED TEMPS IN THE WAKE OF THE FRONT AND PULLED MENTION OF SEA FOG W/ ITS PASSAGE AS WELL. SOME DIFFERENCES IN THE MEDIUM RANGE SOLNS THIS WEEKEND AND BEYOND. ECMWF IS QUICK TO BRING A RETURN OF MOISTURE AND PRECIP CHANCES ACROSS SRN PARTS OF THE AREA LATE SAT WHILE GFS BRINGS A WEAK REINFORCING BOUNDARY OFF THE COAST AT THAT TIME. NO REAL CONFIDENCE IN EITHER ONE AT THIS POINT. BOTH DO INDICATE A 1040+MB HIGH SLIDING SWD INTO THE PLAINS NEXT WEEK AND SENDING ASSOCIATED FRONT INTO OUR REGION AROUND 25TH OR 26TH. 47 MARINE... GENERALLY LIGHT/MODERATE ONSHORE WINDS WILL PREVAIL THROUGH MUCH OF THIS WEEK. A WEAK COLD FRONT IS EXPECTED TO MOVE INTO THE NRN PARTS OF SE TX TONIGHT BUT SHOULD STALL BEFORE IT REACHES THE COAST. AS A RESULT...WINDS OVER THE COASTAL WATERS SHOULD REMAIN OUT OF THE SSE. A SECOND STRONGER FRONT IS FCST TO MOVE THROUGH THE AREA LATER THIS WEEK (LIKELY THURS NIGHT/EARLY FRI MORNING). UNTIL THEN SEA FOG MAY BE AN ISSUE FOR THE BAYS/NEARSHORE WATERS AS THE WARMER AIRMASS OV- ERRIDES THE COOLER SHELF WATERS. ONSHORE WINDS COULD GET STRENGTHEN ENOUGH BY WEDS NIGHT/THURS FOR CAUTION FLAGS. 41 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 77 55 76 61 77 / 10 10 10 10 10 HOUSTON (IAH) 78 60 76 63 77 / 10 10 10 10 10 GALVESTON (GLS) 70 60 69 61 70 / 10 10 10 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY...WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. && $$ DISCUSSION...23 AVIATION/MARINE...42
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
311 PM CST MON FEB 17 2014 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 310 PM CST MON FEB 17 2014 CURRENTLY AS OF 21Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED NEARLY ZONAL FLOW ACROSS MUCH OF THE NORTHERN U.S....WITH THE BIG EXCEPTION FOR A NARROW BUT POTENT/DEEP SHORTWAVE TROUGH EXTENDING FROM MINNESOTA INTO EASTERN MISSOURI. STRONG LIFT AHEAD OF THE TROUGH COMBINED WITH A SURGE OF PRECIPITABLE WATER AROUND A 0.5 INCH PER 12Z MPX SOUNDING BROUGHT SNOW TO MUCH OF THE FORECAST AREA. THIS SNOW WAS VERY EFFICENT IN REDUCING VISIBILITIES...WITH MANY LOCATIONS SEEING 3-4 HOURS OF 1/2 MILE OR LESS...AIDED TOO BY WINDS THAT GUSTED 20 TO 30 MPH. ROADS QUICKLY DETEORIATED TOO. SNOWFALL ACCUMULATIONS...ON THE OTHER HAND...WERE LESS THAN EXPECTED DESPITE THE STRONG FORCING. BELIEVE SOME LEFT-OVER DRY AIR SEEN ON THE 12Z DVN SOUNDING ABSORBED SOME OF THE SNOW...AND KEPT THE SNOW FROM ORGANIZING INTO ONE SOLID AREA. IT ALSO APPEARS THAT THE STRONGEST LIFT ENDED UP SHIFTING SOUTH...INITALLY PROGGED OVER NORTHERN WISCONSIN ON FRIDAY TO OVER THE FORECAST AREA YESTERDAY AND IN REALITY ENDED UP OVER ILLINOIS. STRONG SUBSIDENCE IN THE WAKE OF THE SHORTWAVE TROUGH HAS LED TO CLEARING SKIES IN MN AND IA. WARMER AIR IS ALSO ACCOMPANYING THE CLEARING...WITH READINGS IN THE 30S ALONG AND WEST OF I-35. ANY LINGERING SNOW ALONG/EAST OF THE MISSISSIPPI RIVER WILL PUSH OFF TO THE EAST EARLY THIS EVENING. CLEARING SHOULD THEN WORK ITS WAY ACROSS THE FORECAST AREA TONIGHT AS 500MB HEIGHTS RISE IN THE WAKE OF THE SHORTWAVE TROUGH. ATTENTION THEN TURNS TO A STRING OF SHORTWAVES STRETCHING FROM WASHINGTON STATE INTO SOUTHERN SASKATCHEWAN. THESE SHORTWAVES ARE PROGGED BY ALL MODELS TO DIG INTO THE REGION TUESDAY AFTERNOON. AHEAD OF THESE SHORTWAVES...A PLUME OF WARMER 925-850MB AIR IS FORECAST...WITH 925MB TEMPS CLIMBING TO 2-6C BY 12Z TUESDAY. THESE TEMPS GRADUALLY COOL THROUGH THE DAY AS THE SHORTWAVES APPROACH...BUT THE COMBINATION OF FILTERED SUNSHINE AND THESE WARMER TEMPS SHOULD ALLOW HIGHS TO CLIMB INTO THE MID 30S TO LOW 40S. BOTH THE 17.12Z GFS AND ECMWF HINT AT SOME LIGHT QPF PRODUCED FROM THESE SHORTWAVES AS WELL IN THE AFTERNOON. SOUNDINGS DEPICT A DRY LAYER BETWEEN 700-900MB TO OVERCOME...SO FOR NOW HAVE KEPT ANY PRECIPITATION OUT OF THE FORECAST. WOULD NOT BE SURPRISED IF SOME SPRINKLES OCCUR...THOUGH. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 310 PM CST MON FEB 17 2014 THERE ARE TWO ITEMS OF CONCERN IN THE LONG TERM...A POSSIBLE HIGH IMPACT WINTER STORM FOR THURSDAY...AND THEN MORE BELOW NORMAL TEMPERATURES FOR FRIDAY AND BEYOND. WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...MENTIONED IN YESTERDAYS DISCUSSION MODELS HAD TRENDED AWAY FROM HAVING A CENTRAL PLAINS STORM AFFECTING THE AREA. THAT HAS COMPLETELY CHANGED WITH THE 17.12Z MODELS. THE EVOLUTION OF THIS STORM IS A RESULT OF PHASING OF TWO SHORTWAVE TROUGHS...AT 12Z THURSDAY PROGGED OVER KANSAS AND THE DAKOTAS. THE PHASING LOOKS TO BEGIN OVER THE FORECAST AREA THURSDAY AFTERNOON...RESULTING IN A RAPIDLY DEEPENING SURFACE LOW BEING PULLED NORTH FROM EASTERN KANSAS INTO UPPER MI. PLENTIFUL MOISTURE FROM THE GULF OF MEXICO SHOULD ADVECT NORTH INTO THE FORECAST AREA AHEAD OF THE STORM...WITH PRECIPITABLE WATER VALUES PROGGED TO REACH 0.5-0.75 INCHES. WITH 17.12Z MODEL CONSENSUS ALL HEADING TOWARD THE PHASED IDEA...INCREASING PRECIPITATION CHANCES...ESPECIALLY FOR THURSDAY. BEING PHASED...THERE ARE GOING TO BE ISSUES... 1. PRECIPITATION TYPE. THERE IS SOME WARM AIR AROUND WEDNESDAY NIGHT...WITH WARM LAYER ALOFT TEMPS AROUND 3C...WHICH WHEN THE INITIAL PRECIPITATION STARTS TO FALL COULD END UP BEING AS RAIN...FREEZING RAIN OR SLEET. EVAPORATIVE COOLING SHOULD THEN ALLOW THE TYPE TO GO OVER TO SNOW. THIS IS TEMPORARY FOR THE SOUTHEAST HALF OF THE FORECAST AREA...BECAUSE AS WE HEAD INTO THE DAY THURSDAY...WARM AIR COMES BACK IN FROM THE SOUTH. AT THE SAME TIME DAYTIME HEATING IS HELPING TO BRING TEMPERATURES UP INTO THE MID 30S ALONG THE MS RIVER AND EAST. SO A MIX WITH RAIN IS POSSIBLE. THESE PRECIPITATION TYPE ISSUES ARE GOING TO CREATE HAVOC WITH FORECASTING SNOWFALL AMOUNTS. 2. SNOWFALL AMOUNTS. THE NORTHWEST / DEFORMATION SIDE OF THIS STORM COULD EASILY PUT DOWN SOME HEAVY SNOW IF THE PHASING OCCURS AS PLANNED. THE NEW 17.18Z NAM REALLY HITS AN AREA FROM NORTH CENTRAL IOWA INTO CENTRAL WISCONSIN HARD WITH UPWARDS OF 1-1.5 INCHES OF QPF. THIS IS ON THE HIGH SIDE OF ALL AVAILABLE GUIDANCE...INCLUDING THE 15.09Z/15.15Z SREF...BUT REFLECTS THAT WE NEED TO WATCH THE STORM. WHERE THE DEFORMATION TRACKS TOO DEPENDS ON THE STORM TRACK. 3. WINDS ON THE BACK SIDE FOR THURSDAY AFTERNOON/NIGHT. 925MB WINDS FROM THE 17.12Z GFS AND ECMWF ARE SUGGESTED TO INCREASE TO 30-40 KT IN A STRONG COLD ADVECTION REGIME THURSDAY EVENING. THESE WINDS COULD RESULT IN EXTENSIVE BLOWING OF THE SNOW. INCREASED WINDS AND MENTIONED BLOWING SNOW...BUT MAY NEED TO RAISE WINDS MORE. WITH THE CURRENT STORM SYSTEM STILL LINGERING AROUND...AND THAT THE MODELS HAVE JUST TRENDED BACK TO A PHASED SYSTEM...HAVE DECIDED NOT TO ISSUE A WINTER STORM WATCH AT THIS POINT. HOWEVER...SHOULD MODELS SHOW THE SAME THING AGAIN TONIGHT...WATCHES MAY BE NEEDED... ESPECIALLY OVER THE NORTHWEST HALF OF THE FORECAST AREA. FRIDAY INTO EARLY NEXT WEEK...17.12Z GFS/ECMWF/CANADIAN REMAIN IN GOOD AGREEMENT ON A COOL DOWN EACH DAY. THIS COOL DOWN IS A RESULT OF AN OMEGA BLOCK THAT DEVELOPS FROM ALASKA DOWN THE WEST COAST OF THE U.S...CAUSING DEEP TROUGHING OVER MUCH OF CANADA INTO THE UPPER MIDWEST. FOLLOWING A MODEL CONSENSUS FORECAST...WE COULD BE APPROACHING WIND CHILL ADVISORY CONCERNS AGAIN AS EARLY AS MONDAY. EVEN COLDER AIR APPEARS TO BE LURKING BEYOND MONDAY...ESPECIALLY IN THE ECMWF AND CFS. THIS DEEP UPPER TROUGHING FORMING PUSHES MOST PRECIPITATING SYSTEMS SOUTH OF THE FORECAST AREA...BUT DO HAVE SOME LOW CHANCES OF SNOW HERE AND THERE FOR SHORTWAVES TRAVERSING THE BOTTOM OF THE TROUGH. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY NOON) ISSUED AT 1135 AM CST MON FEB 17 2014 BAND OF MDT/HEAVY SNOW WITH IFR/LIFR VSBYS AND IFR/MVFR CIGS CONTINUED TO MOVE EAST ACROSS THE FCST AREA AT MID-DAY. BACK EDGE OF THIS BAND WAS ALREADY MOVING INTO THE KRST AREA...WITH DECREASING CLOUDS/CLEARING ALREADY APPROACHING I-35. TRENDED KRST FOR IMPROVING CONDITIONS THRU THE 18-21Z PERIOD. FURTHER EAST...DISTANCE-SPEED TOOL HAS THE HEAVIER SNOW MOVING EAST OF KLSE BY 1930Z THEN ENDING BY MID AFTERNOON...WITH THE DECREASE OF CLOUDS MOVING IN AROUND 22Z. WILL NEED TO WATCH THE DECREASE OF CLOUDS AT BOTH KRST/KLSE...AS APPEARS SOME MVFR CLOUDS MAY PIVOT SOUTHEAST FROM WEST OF KMSP AND HOLD MVFR CIGS ACROSS SOUTHEAST MN/WESTERN WI LATER INTO THE AFTERNOON AS FLOW BECOMES NORTHWEST BEHIND THE SNOW BAND INTO EARLY THIS EVENING. SFC-700MB FLOW TURNS BACK TO THE WEST AND SOUTHWEST BY LATER THIS EVENING AS THE NEXT TROUGH MOVES INTO THE NORTHERN PLAINS...WHICH WOULD ADVECT ANY MVFR CLOUDS THAT MAY LINGER OUT OF THE AREA DURING THE EVENING. GOOD VFR EXPECTED FOR THE LATE EVENING THRU MORNING HOURS OF TUE. STRONG WARMING AND THE SOUTHWEST FLOW TUE MAY PUSH SOME BOUNDARY LAYER MOISTURE FROM MELTING SNOW ACROSS IA NORTHWARD FOR TUE...FOR WHAT MAY BE SOME SCT MVFR CLOUDS BY LATE MORNING AND FOR TUE AFTERNOON. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR WIZ017-029- 034-042>044-053>055-061. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...RRS