Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 11/25/12
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1014 PM EST SAT NOV 24 2012
.SYNOPSIS...
COOL AND BLUSTERY CONDITIONS ARE EXPECTED FOR THE REMAINDER OF
THE WEEKEND INTO EARLY NEXT WEEK. UNCERTAINTY REMAINS REGARDING
THE TRACK AND INTENSITY OF A STORM TUESDAY AND WEDNESDAY. MUCH
COLDER WEATHER IS EXPECTED BEHIND THE STORM LATE NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
10 PM UPDATE...
MOST OF THE LIGHT FLURRIES AND SPRINKLES HAVE DISSIPATED IN THE
LAST HOUR OR SO THANKS TO NEAR SFC INSTABILITY WANING AND LOSS OF
CONNECTION TO THE LOW-MID LVL MOISTURE PROVIDED FROM THE LAKE
EFFECT SNOWS WELL UPSTREAM. THEREFORE...ALTHOUGH A FEW MORE
FLURRIES OVERNIGHT CAN/T BE RULED OUT AS COMPLETE DECOUPLING IS
UNLIKELY WITH SHORTWAVE ROTATING INTO NRN NEW ENGLAND...EXPECT
THAT MUCH OF THE REMAINDER OF THE NIGHT WILL REMAIN DRY ACROSS
INTERIOR SRN NEW ENGLAND. OTHERWISE...TEMPS/DWPTS ARE ALREADY
DROPPING OFF RAPIDLY DESPITE THE WINDS REMAINING FAIRLY STRONG
ACROSS THE AREA. HAVE ADJUSTED THE TEMPS/DWPTS ALONG WITH
POPS/SKIES/WX TO ACCOUNT FOR RECENT TRENDS AND THINKING FOR THE
REMAINDER OF THE NIGHT.
PREVIOUS DISCUSSION...
430 PM UPDATE... WINDS HAVE INCREASED LATE THIS AFTERNOON AS THE
MIXING DEPTH GETS TO NEAR 850 MB. A GUST TO 44 KTS JUST OCCURRED
AT WORCESTER AT 4 PM... WITH 32 KTS WAS REPORTED AT ORANGE MA AND
33 KTS AT PITTSFIELD AT 3 PM. THE NORTHWEST PRESSURE GRADIENT WILL
CONTINUE TO TIGHTEN UP THIS EVENING AND OVERNIGHT IN THE WAKE OF
AN UPPER LEVEL TROUGH SWINGING ACROSS NORTHERN NEW ENGLAND. WINDS
AT 3000-5000 FT OFF THE GROUND ARE FORECAST TO INCREASE TO 40-45
KNOTS OVERNIGHT. IT IS A TRICKY CALL FOR THE WINDS TONIGHT. BUFKIT
SHOWS THAT DESPITE THE COLD AIR ADVECTION...THE WINDS DIMINISH TO
15 KT OVER MOST OF THE INTERIOR AS THE TEMPERATURE DROPS AND THE
MIXING LEVEL IS NOT AS DEEP. A MAJOR EXCEPTION IS ALONG THE
COAST...EVERYWHERE FROM CAPE ANN TO CAPE COD AND ON THE RI
COAST...WHERE IT SHOULD REMAIN GUSTING TO 25 TO 30 KTS OVERNIGHT.
FOR THE MOST PART...LAKE EFFECT SNOW SHOWERS HAVE BEEN CONFINED TO
THE BERKSHIRES. HOWEVER...A LIGHT SPRINKLE WAS REPORTED AT 3 PM IN
NASHUA NH... SO SOME OF THE PRECIPITATION IS HITTING THE GROUND.
CANNOT RULE OUT A FLAKE OF SNOW MAINLY WEST OF THE CONNECTICUT
RIVER THIS EVENING BUT ACTIVITY SHOULD DIMINISH WITH NIGHTFALL.
THE RAP MODEL SHOWS NO PRECIPITATION AFTER 04Z.
LOWS MAINLY IN THE UPPER TEENS TO MID 20S EXCEPT NEAR 30 ALONG THE
IMMEDIATE SOUTH COAST.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
SUNDAY...
SHOULD BE RATHER SIMILAR TO TODAY. SUNSHINE SHOULD GIVE WAY TO A
FAST MOVING BATCH OF MID LEVEL CLOUDINESS IN THE AFTERNOON LEADING
TO PARTLY TO MOSTLY CLOUDY SKIES. USED A 50-50 BLEND OF GFS AND
NAM FOR SKY GRIDS SINCE THEY DIFFERED ON THE TIMING OF THESE CLOUDS.
IT WILL AGAIN BECOME WINDY WITH GUSTS TO 20 TO 30 KTS FROM MID
MORNING THROUGH MID AFTERNOON AS THE MIXING INCREASES. WINDS
SHOULD DIMINISH LATE IN THE AFTERNOON. HIGHS MAINLY IN THE 40S.
SUNDAY NIGHT...
BECOMING MOSTLY CLEAR WITH LIGHT WINDS AND LOWS 20-30.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
* COLDER...DRY WEATHER EXPECTED EARLY NEXT WEEK
* A STORM IS LIKELY TO AFFECT THE AREA MID WEEK
* COLDER WEATHER EXPECTED LATE NEXT WEEK
24/12Z MODELS ARE STARTING TO SHOW SOME CONSISTENCY THROUGHOUT THE
LONG TERM PORTION OF THE FORECAST. THERE IS STILL PLENTY OF
UNCERTAINTY REGARDING THE MID WEEK STORM...THOUGH THE 06Z GFS/00Z
ECMWF/12Z GFS ALL HAVE SIMILAR SOLUTIONS WITH LOW PRESSURE MOVING
OFF THE MID ATLANTIC COAST AND TRAVELING JUST SOUTH OF THE 40/70
BENCHMARK AND BRINGING SNOW TO MUCH OF THE AREA WITH A FOCUS ON THE
SOUTHERN PORTIONS OF SOUTHERN NEW ENGLAND. HOWEVER...THE 12Z NAM
/AN OUTLIER AT THIS POINT/ SIMPLY HAS HIGH PRESSURE OVER THE REGION
AND NO INDICATION OF PRECIP AT ALL. WILL TREND TOWARD A
ECMWF/GFS/HPC SOLUTION... HOWEVER...KEEPING IN MIND ALL THE FLIP
FLOPPING AND UNCERTAINTY WILL ONLY TREND TOWARD IT.
ASIDE FROM THE STORM...THE WEATHER IS FAIRLY QUIET BOTH EARLY AND
LATE NEXT WEEK WITH NORTHWESTERLY FLOW BRINGING COLDER TEMPERATURES.
MONDAY...STRONG NORTHWESTERLY FLOW WILL CONTINUE TO KEEP TEMPS
SLIGHTLY BELOW NORMAL. HIGH PRESSURE BUILDS IN KEEPING MOSTLY CLEAR
SKIES THROUGH THE DAY AND INTO THE EVENING.
TUESDAY INTO WEDNESDAY...GIVEN THE NUMEROUS SOLUTIONS OVER THE LAST
SEVERAL DAYS AM STILL HESITANT TO MAKE A RUN FOR A SINGLE SOLUTION.
THAT SAID...THE ECMWF AND GFS HAVE STARTED TO FOCUS TOWARDS LOW
PRESSURE ON A SOUTHERLY TRACK ALONG OR JUST SOUTH OF THE 40/70
BENCHMARK FOR WINTER STORMS. AT THIS POINT...THIS SOLUTION BRINGS
HEAVY SNOW...LIKELY FOCUSED MORE ON THE SOUTHERN AREAS OF THE CWA
MAINLY ON TUESDAY NIGHT INTO WEDNESDAY. THERE ARE STILL OTHER
SOLUTIONS...THE NAM HAS HIGH PRESSURE OVER THE REGION TUESDAY.
HOWEVER...AT THIS POINT...THE ECMWF/GFS SOLUTION APPEARS THE MOST
LIKELY. WILL TREND TOWARD THIS SOLUTION...BUT CONFIDENCE IS STILL
LOW.
THURSDAY AND FRIDAY...DESPITE ALL THE DISCREPANCIES/UNCERTAINTY FOR
EARLIER IN THE PERIOD...THESE TWO PERIODS HAVE FAIRLY GOOD AGREEMENT
AMONGST THE MODELS. NORTHWESTERLY FLOW WITH THE COOLEST TEMPS OF
THE SEASON THUS FAR MOVING IN ON STRONG COLD AIR ADVECTION. LOOKS
LIKE A COLD AND BRISK END TO THE WEEK.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
OVERVIEW...MODERATE TO HIGH CONFIDENCE.
VFR CONDITIONS THROUGH SUNDAY NIGHT. SCATTERED LIGHT SNOW SHOWERS
SHOULD BE CONFINED TO BERKSHIRES THIS EVENING ALTHOUGH A FLAKE OR
TWO CANNOT BE RULED OUT BEFORE 04Z. W-NW WINDS GUSTING TO 20-30
KTS MOST AREAS. WINDS MAY DIMINISH TO 15 KTS IN THE INTERIOR
OVERNIGHT AND INCREASING AGAIN AFTER DAYBREAK. WINDS DIMINISHING
AGAIN IN THE LATE AFTERNOON SUNDAY EXCEPT ALONG THE COAST.
KBOS TAF...MODERATE TO HIGH CONFIDENCE. VFR THROUGH SUNDAY NIGHT.
W-NW WINDS WITH GUSTS TO 20-30 KT TONIGHT AND SUNDAY.
KBDL TAF...HIGH CONFIDENCE. VFR THROUGH SUNDAY NIGHT. SLIGHT
CHANCE OF A FLURRY THIS EVENING. W-NW WINDS WITH GUSTS 20-30 KT
THIS EVENING AND AGAIN SUNDAY MID MORNING THROUGH MID AFTERNOON.
OUTLOOK...MONDAY THROUGH THURSDAY...
MONDAY...HIGH CONFIDENCE. VFR.
TUESDAY THROUGH WEDNESDAY MORNING...LOW CONFIDENCE. MVFR/IFR
CONDITIONS POSSIBLE IN POTENTIAL RA/SN/FZRA/SNPL.
WEDNESDAY AFTERNOON THROUGH THURSDAY...MODERATE TO HIGH CONFIDENCE.
VFR.
&&
.MARINE...
MODERATE CONFIDENCE INTO SUNDAY NIGHT...
GALE WARNINGS CONTINUE FOR THE COASTAL WATERS INCLUDING NANTUCKET
SOUND...EXCEPT FOR THE INNER HARBORS AND BAYS WHERE SMALL CRAFT
ADVISORIES ARE POSTED. AS AN UPPER LEVEL SHORT WAVE TROUGH SWINGS
THROUGH NORTHERN NEW ENGLAND OVERNIGHT...W TO NW WINDS WILL
CONTINUE TO INCREASE OVER THE COASTAL WATERS...REACHING 35 KTS
OVER THE GALE WARNING AREA AND CONTINUING INTO MUCH OF SUNDAY.
THERE IS A CHANCE THAT A FEW GUSTS TO GALE FORCE COULD OCCUR
CLOSER TO THE COAST IN THE SMALL CRAFT ADVISORY AREA...BUT
FREQUENT GUSTS ARE NOT EXPECTED. ONE CONCERN IS A GUST TO 44 KTS
AT WORCESTER AIRPORT RIGHT AT 4 PM... BUT WE ARE THINKING THAT
THIS IS ELEVATIONAL AND STILL RELATED TO THE MAXIMUM MIXING OF THE
AFTERNOON. WE WILL NEED TO WATCH THIS CLOSELY IN CASE GALES ARE
NEEDED EVERYWHERE ALONG THE COAST OVERNIGHT.
SEAS ARE FORECAST TO CONTINUE TO BUILD TO 8 TO 11 FEET ACROSS THE
OUTER WATERS TONIGHT.
WINDS SHOULD BEGIN TO DIMINISH TO BELOW GALE FORCE IN THE
AFTERNOON BUT SMALL CRAFT ADVISORY LEVEL WIND GUSTS TO 25 KTS MAY
CONTINUE OVER THE OUTER WATERS THROUGH SUNDAY NIGHT. SLOWLY
SUBSIDING SEAS SUNDAY NIGHT.
OUTLOOK...MONDAY THROUGH THURSDAY...
MODERATE CONFIDENCE THROUGH THE PERIOD.
SEAS WILL FALL BELOW 5 FEET LATE MONDAY AND REMAIN BELOW THROUGH
LATE TUESDAY. THEN SEAS WILL BUILD AGAIN AS LOW PRESSURE APPROACHES
THE WATERS LATE TUESDAY INTO WEDNESDAY AND REMAIN ABOVE 5 FEET
THROUGH THE PERIOD. WINDS WILL REMAIN BELOW 25 KTS THROUGH TUESDAY.
WINDS INCREASE TO 25 TO 30 KTS WEDNESDAY AND THURSDAY AS LOW
PRESSURE MOVES ACROSS THE WATERS. LOW PROBABILITY OF GALES LATE
WEDNESDAY INTO THURSDAY.
&&
.FIRE WEATHER...
NO HEADLINES ARE ANTICIPATED BUT FELT IT WAS WORTH MENTIONING THAT
THE MINIMUM RELATIVE HUMIDITIES WILL BE DOWN AROUND 30 PERCENT
SUNDAY AFTERNOON. WINDS WILL BE GUSTING TO 20 TO 30 MPH BUT WILL
BE DIMINISHING IN THE MID TO LATE AFTERNOON AT THE TIME OF THE
MINIMUM HUMIDITIES.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...GALE WARNING UNTIL 10 AM EST SUNDAY FOR ANZ232>235-237-256.
SMALL CRAFT ADVISORY UNTIL 7 PM EST SUNDAY FOR ANZ230-231-236-
251.
GALE WARNING UNTIL 1 PM EST SUNDAY FOR ANZ250-254-255.
&&
$$
SYNOPSIS...RLG/GAF
NEAR TERM...DOODY/RLG/GAF
SHORT TERM...GAF
LONG TERM...RLG
AVIATION...RLG/GAF
MARINE...RLG/GAF
FIRE WEATHER...
AREA FORECAST DISCUSSION...CORRECTED
NWS TAUNTON MA
629 PM EST SAT NOV 24 2012
.SYNOPSIS...
COOL AND BLUSTERY CONDITIONS ARE EXPECTED FOR THE REMAINDER OF
THE WEEKEND INTO EARLY NEXT WEEK. UNCERTAINTY REMAINS REGARDING
THE TRACK AND INTENSITY OF A STORM TUESDAY AND WEDNESDAY. MUCH
COLDER WEATHER IS EXPECTED BEHIND THE STORM LATE NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
630 PM UPDATE...MADE MINOR UPDATES TO TEMPERATURES AND SKY COVER.
ALSO ADDED SPRINKLES AND FLURRIES TO THE GRIDS FOR THE NEXT COUPLE
OF HOURS FOR THE REMAINING LIGHT RADAR ECHOES. OTHERWISE...THE
FORECAST IS ON TRACK.
430 PM UPDATE... WINDS HAVE INCREASED LATE THIS AFTERNOON AS THE
MIXING DEPTH GETS TO NEAR 850 MB. A GUST TO 44 KTS JUST OCCURRED
AT WORCESTER AT 4 PM... WITH 32 KTS WAS REPORTED AT ORANGE MA AND
33 KTS AT PITTSFIELD AT 3 PM. THE NORTHWEST PRESSURE GRADIENT WILL
CONTINUE TO TIGHTEN UP THIS EVENING AND OVERNIGHT IN THE WAKE OF
AN UPPER LEVEL TROUGH SWINGING ACROSS NORTHERN NEW ENGLAND. WINDS
AT 3000-5000 FT OFF THE GROUND ARE FORECAST TO INCREASE TO 40-45
KNOTS OVERNIGHT. IT IS A TRICKY CALL FOR THE WINDS TONIGHT. BUFKIT
SHOWS THAT DESPITE THE COLD AIR ADVECTION...THE WINDS DIMINISH TO
15 KT OVER MOST OF THE INTERIOR AS THE TEMPERATURE DROPS AND THE
MIXING LEVEL IS NOT AS DEEP. A MAJOR EXCEPTION IS ALONG THE
COAST...EVERYWHERE FROM CAPE ANN TO CAPE COD AND ON THE RI
COAST...WHERE IT SHOULD REMAIN GUSTING TO 25 TO 30 KTS OVERNIGHT.
FOR THE MOST PART...LAKE EFFECT SNOW SHOWERS HAVE BEEN CONFINED TO
THE BERKSHIRES. HOWEVER...A LIGHT SPRINKLE WAS REPORTED AT 3 PM IN
NASHUA NH... SO SOME OF THE PRECIPITATION IS HITTING THE GROUND.
CANNOT RULE OUT A FLAKE OF SNOW MAINLY WEST OF THE CONNECTICUT
RIVER THIS EVENING BUT ACTIVITY SHOULD DIMINISH WITH NIGHTFALL.
THE RAP MODEL SHOWS NO PRECIPITATION AFTER 04Z.
LOWS MAINLY IN THE UPPER TEENS TO MID 20S EXCEPT NEAR 30 ALONG THE
IMMEDIATE SOUTH COAST.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
SUNDAY...
SHOULD BE RATHER SIMILAR TO TODAY. SUNSHINE SHOULD GIVE WAY TO A
FAST MOVING BATCH OF MID LEVEL CLOUDINESS IN THE AFTERNOON LEADING
TO PARTLY TO MOSTLY CLOUDY SKIES. USED A 50-50 BLEND OF GFS AND
NAM FOR SKY GRIDS SINCE THEY DIFFERED ON THE TIMING OF THESE CLOUDS.
IT WILL AGAIN BECOME WINDY WITH GUSTS TO 20 TO 30 KTS FROM MID
MORNING THROUGH MID AFTERNOON AS THE MIXING INCREASES. WINDS
SHOULD DIMINISH LATE IN THE AFTERNOON. HIGHS MAINLY IN THE 40S.
SUNDAY NIGHT...
BECOMING MOSTLY CLEAR WITH LIGHT WINDS AND LOWS 20-30.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
* COLDER...DRY WEATHER EXPECTED EARLY NEXT WEEK
* A STORM IS LIKELY TO AFFECT THE AREA MID WEEK
* COLDER WEATHER EXPECTED LATE NEXT WEEK
24/12Z MODELS ARE STARTING TO SHOW SOME CONSISTENCY THROUGHOUT THE
LONG TERM PORTION OF THE FORECAST. THERE IS STILL PLENTY OF
UNCERTAINTY REGARDING THE MID WEEK STORM...THOUGH THE 06Z GFS/00Z
ECMWF/12Z GFS ALL HAVE SIMILAR SOLUTIONS WITH LOW PRESSURE MOVING
OFF THE MID ATLANTIC COAST AND TRAVELING JUST SOUTH OF THE 40/70
BENCHMARK AND BRINGING SNOW TO MUCH OF THE AREA WITH A FOCUS ON THE
SOUTHERN PORTIONS OF SOUTHERN NEW ENGLAND. HOWEVER...THE 12Z NAM
/AN OUTLIER AT THIS POINT/ SIMPLY HAS HIGH PRESSURE OVER THE REGION
AND NO INDICATION OF PRECIP AT ALL. WILL TREND TOWARD A
ECMWF/GFS/HPC SOLUTION... HOWEVER...KEEPING IN MIND ALL THE FLIP
FLOPPING AND UNCERTAINTY WILL ONLY TREND TOWARD IT.
ASIDE FROM THE STORM...THE WEATHER IS FAIRLY QUIET BOTH EARLY AND
LATE NEXT WEEK WITH NORTHWESTERLY FLOW BRINGING COLDER TEMPERATURES.
MONDAY...STRONG NORTHWESTERLY FLOW WILL CONTINUE TO KEEP TEMPS
SLIGHTLY BELOW NORMAL. HIGH PRESSURE BUILDS IN KEEPING MOSTLY CLEAR
SKIES THROUGH THE DAY AND INTO THE EVENING.
TUESDAY INTO WEDNESDAY...GIVEN THE NUMEROUS SOLUTIONS OVER THE LAST
SEVERAL DAYS AM STILL HESITANT TO MAKE A RUN FOR A SINGLE SOLUTION.
THAT SAID...THE ECMWF AND GFS HAVE STARTED TO FOCUS TOWARDS LOW
PRESSURE ON A SOUTHERLY TRACK ALONG OR JUST SOUTH OF THE 40/70
BENCHMARK FOR WINTER STORMS. AT THIS POINT...THIS SOLUTION BRINGS
HEAVY SNOW...LIKELY FOCUSED MORE ON THE SOUTHERN AREAS OF THE CWA
MAINLY ON TUESDAY NIGHT INTO WEDNESDAY. THERE ARE STILL OTHER
SOLUTIONS...THE NAM HAS HIGH PRESSURE OVER THE REGION TUESDAY.
HOWEVER...AT THIS POINT...THE ECMWF/GFS SOLUTION APPEARS THE MOST
LIKELY. WILL TREND TOWARD THIS SOLUTION...BUT CONFIDENCE IS STILL
LOW.
THURSDAY AND FRIDAY...DESPITE ALL THE DISCREPANCIES/UNCERTAINTY FOR
EARLIER IN THE PERIOD...THESE TWO PERIODS HAVE FAIRLY GOOD AGREEMENT
AMONGST THE MODELS. NORTHWESTERLY FLOW WITH THE COOLEST TEMPS OF
THE SEASON THUS FAR MOVING IN ON STRONG COLD AIR ADVECTION. LOOKS
LIKE A COLD AND BRISK END TO THE WEEK.
&&
.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
OVERVIEW...MODERATE TO HIGH CONFIDENCE.
VFR CONDITIONS THROUGH SUNDAY NIGHT. SCATTERED LIGHT SNOW SHOWERS
SHOULD BE CONFINED TO BERKSHIRES THIS EVENING ALTHOUGH A FLAKE OR
TWO CANNOT BE RULED OUT BEFORE 04Z. W-NW WINDS GUSTING TO 20-30
KTS MOST AREAS. WINDS MAY DIMINISH TO 15 KTS IN THE INTERIOR
OVERNIGHT AND INCREASING AGAIN AFTER DAYBREAK. WINDS DIMINISHING
AGAIN IN THE LATE AFTERNOON SUNDAY EXCEPT ALONG THE COAST.
KBOS TAF...MODERATE TO HIGH CONFIDENCE. VFR THROUGH SUNDAY NIGHT.
W-NW WINDS WITH GUSTS TO 20-30 KT TONIGHT AND SUNDAY.
KBDL TAF...HIGH CONFIDENCE. VFR THROUGH SUNDAY NIGHT. SLIGHT
CHANCE OF A FLURRY THIS EVENING. W-NW WINDS WITH GUSTS 20-30 KT
THIS EVENING AND AGAIN SUNDAY MID MORNING THROUGH MID AFTERNOON.
OUTLOOK...MONDAY THROUGH THURSDAY...
MONDAY...HIGH CONFIDENCE. VFR.
TUESDAY THROUGH WEDNESDAY MORNING...LOW CONFIDENCE. MVFR/IFR
CONDITIONS POSSIBLE IN POTENTIAL RA/SN/FZRA/SNPL.
WEDNESDAY AFTERNOON THROUGH THURSDAY...MODERATE TO HIGH CONFIDENCE.
VFR.
&&
.MARINE...
MODERATE CONFIDENCE INTO SUNDAY NIGHT...
GALE WARNINGS CONTINUE FOR THE COASTAL WATERS INCLUDING NANTUCKET
SOUND...EXCEPT FOR THE INNER HARBORS AND BAYS WHERE SMALL CRAFT
ADVISORIES ARE POSTED. AS AN UPPER LEVEL SHORT WAVE TROUGH SWINGS
THROUGH NORTHERN NEW ENGLAND OVERNIGHT...W TO NW WINDS WILL
CONTINUE TO INCREASE OVER THE COASTAL WATERS...REACHING 35 KTS
OVER THE GALE WARNING AREA AND CONTINUING INTO MUCH OF SUNDAY.
THERE IS A CHANCE THAT A FEW GUSTS TO GALE FORCE COULD OCCUR
CLOSER TO THE COAST IN THE SMALL CRAFT ADVISORY AREA...BUT
FREQUENT GUSTS ARE NOT EXPECTED. ONE CONCERN IS A GUST TO 44 KTS
AT WORCESTER AIRPORT RIGHT AT 4 PM... BUT WE ARE THINKING THAT
THIS IS ELEVATIONAL AND STILL RELATED TO THE MAXIMUM MIXING OF THE
AFTERNOON. WE WILL NEED TO WATCH THIS CLOSELY IN CASE GALES ARE
NEEDED EVERYWHERE ALONG THE COAST OVERNIGHT.
SEAS ARE FORECAST TO CONTINUE TO BUILD TO 8 TO 11 FEET ACROSS THE
OUTER WATERS TONIGHT.
WINDS SHOULD BEGIN TO DIMINISH TO BELOW GALE FORCE IN THE
AFTERNOON BUT SMALL CRAFT ADVISORY LEVEL WIND GUSTS TO 25 KTS MAY
CONTINUE OVER THE OUTER WATERS THROUGH SUNDAY NIGHT. SLOWLY
SUBSIDING SEAS SUNDAY NIGHT.
OUTLOOK...MONDAY THROUGH THURSDAY...
MODERATE CONFIDENCE THROUGH THE PERIOD.
SEAS WILL FALL BELOW 5 FEET LATE MONDAY AND REMAIN BELOW THROUGH
LATE TUESDAY. THEN SEAS WILL BUILD AGAIN AS LOW PRESSURE APPROACHES
THE WATERS LATE TUESDAY INTO WEDNESDAY AND REMAIN ABOVE 5 FEET
THROUGH THE PERIOD. WINDS WILL REMAIN BELOW 25 KTS THROUGH TUESDAY.
WINDS INCREASE TO 25 TO 30 KTS WEDNESDAY AND THURSDAY AS LOW
PRESSURE MOVES ACROSS THE WATERS. LOW PROBABILITY OF GALES LATE
WEDNESDAY INTO THURSDAY.
&&
.FIRE WEATHER...
NO HEADLINES ARE ANTICIPATED BUT FELT IT WAS WORTH MENTIONING THAT
THE MINIMUM RELATIVE HUMIDITIES WILL BE DOWN AROUND 30 PERCENT
SUNDAY AFTERNOON. WINDS WILL BE GUSTING TO 20 TO 30 MPH BUT WILL
BE DIMINISHING IN THE MID TO LATE AFTERNOON AT THE TIME OF THE
MINIMUM HUMIDITIES.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...GALE WARNING UNTIL 10 AM EST SUNDAY FOR ANZ232>235-237-256.
SMALL CRAFT ADVISORY UNTIL 7 PM EST SUNDAY FOR ANZ230-231-236-
251.
GALE WARNING UNTIL 1 PM EST SUNDAY FOR ANZ250-254-255.
&&
$$
SYNOPSIS...RLG/GAF
NEAR TERM...RLG/GAF
SHORT TERM...GAF
LONG TERM...RLG
AVIATION...RLG/GAF
MARINE...RLG/GAF
FIRE WEATHER...
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1019 PM EST SAT NOV 24 2012
...FROST/FREEZE CONDITIONS TONIGHT...
.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER GEORGIA AND THE CAROLINAS THROUGH
MONDAY. A WEAK COLD FRONT WILL PASS THROUGH LATE TUESDAY WITH HIGH
PRESSURE RETURNING FOR MID TO LATE NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
TEMPERATURES ARE STILL DROPPING RAPIDLY THIS EVENING UNDER CLEAR
SKIES AND LIGHT WINDS. 25/03Z OBSERVATIONS SHOWED SOME INLAND
LOCATIONS HAD ALREADY DROPPED INTO THE MID 30S WITH UPPER
30S TO LOWER 40S MORE COMMON. ALTHOUGH 1-3 KT OF WIND COULD
CERTAINLY OCCUR AT A FEW REPORTING STATIONS THROUGH ABOUT 1-2 AM
AS A SHORTWAVE MOVING RAPIDLY THROUGH THE UPPER SAVANNAH RIVER
AREA MAKES ITS CLOSEST APPROACH...THE STRONG NOCTURNAL INVERSION
NOTED ON THE 25/00Z CHS RAOB AND RAP MODEL SOUNDINGS SUGGEST THE
BOUNDARY LAYER WILL REMAIN DECOUPLED THROUGH SUNRISE. THIS
COUPLED WITH CLEAR SKIES WILL YIELD A NEARLY PERFECT RADIATIONAL
REGIME...ESPECIALLY AFTER 2 AM WHEN ANY SUCH WIND INFLUENCES
SHOULD CEASE AS THE SHORTWAVE MOVES OFFSHORE. 18Z GUIDANCE CAME
IN A BIT COOLER...BUT IS STILL RUNNING SEVERAL DEGREES TOO WARM
PER GOING EVENING THERMAL TRENDS. IN FACT...AS HAS BEEN THE CASE
WITH THE PAST SEVERAL STRONG RADIATIONAL EVENTS...THE ECMWF MOS
HAS BEEN TRENDING THE BEST...ALTHOUGH IT TOO IS RUNNING 1-2
DEGREES TOO WARM THIS EVENING. MADE A FEW MORE MINOR ADJUSTMENTS
TO HOURLY TEMPERATURES AND OVERNIGHT LOWS...BUT STILL EXPECTED
TEMPERATURES TO DROP INTO THE UPPER 20S INLAND WITH LOWER-MID 30S
CLOSER TO THE COAST.
THE CURRENT FREEZE WARNING LOOKS WELL PLACED WITH FREEZING
TEMPERATURES POSSIBLE AS FAR EAST AS AN AWENDAW-WEST ASHLEY-ADAMS
RUN-GARDENS CORNER-HARDEEVILLE LINE IN SOUTHEAST SOUTH CAROLINA
AND A POOLER-RICEBORO-TOWNSEND LINE IN SOUTHEAST GEORGIA. AREAS
ALONG THE I-26 CORRIDOR BETWEEN SUMMERVILLE AND NORTH CHARLESTON
MAY HOLD JUST ABOVE OR JUST TOUCH FREEZING DUE TO SOME URBAN
INFLUENCES AND DOWNTOWN CHARLESTON LOOKS TO REMAIN WELL ABOVE
FREEZING DUE TO THE WARMING INFLUENCES OF THE CHARLESTON HARBOR.
IT COULD BE CLOSE TO FREEZING IN THE OUTER FRINGES OF DOWNTOWN
SAVANNAH...INCLUDING HUNTER ARMY AIRFIELD...BUT THE CORE OF
THE DOWNTOWN AREA LOOKS TO HOLD ABOVE FREEZING...ESPECIALLY NEAR
THE SAVANNAH RIVER. THE TEMPERATURE FORECAST IN BEAUFORT COUNTY IS
ALWAYS A CHALLENGE ON STRONG RADIATIONAL NIGHTS GIVEN THE COUNTY
IS RIDDLED WITH NUMEROUS WATERWAYS...BUT AREAS SUCH AS BLUFFTON
AND GARDENS CORNER WILL LIKELY MAKE A RUN SOLID FOR THE FREEZING
MARK.
FREEZE DURATIONS LOOK TO RANGE FROM 3-5 HOURS ACROSS INTERIOR
PORTIONS OF LIBERTY...BRYAN AND LONG COUNTIES AND CLOSER TO 1-3
HOURS ALONG THE HIGHWAY 17/INTERSTATE 95 CORRIDORS.
IT NOW APPEARS PER GOING EVENING TEMPERATURE TRENDS THAT THE RISK
FOR SCATTERED FROST IS INCREASING ACROSS PORTIONS OF THE GEORGIA
COASTAL ZONES. PER COLLABORATION WITH WFO JACKSONVILLE...A FROST
ADVISORY WILL BE ISSUED FOR MAINLY THE WESTERN HALF OF COASTAL
CHATHAM...COASTAL BRYAN...COASTAL LIBERTY AND COASTAL MCINTOSH.
THIS INCLUDES COMMUNITIES SUCH AS THUNDERBOLT...HALFMOON
LANDING...SHELLMAN BLUFF AND DARIEN.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
BROAD HIGH PRESSURE ACROSS THE REGION SUNDAY WILL SHIFT OFFSHORE
MONDAY WITH A RELATIVELY WEAK COLD FRONT TO PUSH INTO THE AREA
TUESDAY. IT LOOKS TO REMAIN DRY THROUGH MONDAY NIGHT ALTHOUGH HIGH
CLOUDS WILL BE ON THE INCREASE LATE IN THE PERIOD. WEAK UPPER
TROUGH...UPPER JET...SLIGHTLY DEEPER MOISTURE AND THE SURFACE
FRONT WILL LEAD TO ISOLATED/SCATTERED SHOWERS TUESDAY. HIGH
TEMPERATURES WILL REMAIN BELOW NORMAL SUNDAY AND THEN GET BACK
ABOVE NORMAL MONDAY BEFORE RETURNING TO CLOSER TO NORMAL TUESDAY.
LOWS WILL DROP TO AROUND FREEZING MONDAY MORNING INLAND WITH UPPER
30S INLAND TUESDAY MORNING. A FREEZE WATCH AND/OR WARNING COULD
EVENTUALLY BE NEEDED MONDAY MORNING FOR SOME AREAS AWAY FROM THE
IMMEDIATE COAST BUT THIS DEPENDS ON WHETHER FREEZING CONDITIONS
OCCUR SUNDAY MORNING AND THUS WHETHER THE FROST/FREEZE PROGRAM
ENDS.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THE COLD FRONT SHOULD BE OFFSHORE BY LATE TUESDAY NIGHT WITH BROAD
UPPER RIDGING WEDNESDAY INTO SATURDAY. GUIDANCE HAS BEEN SHOWING A
DRYING TREND REGARDING THE FRONT SO WE ARE ONLY CARRYING SLIGHT
CHANCE FOR SHOWERS TUESDAY NIGHT WITH DRY WEATHER THEREAFTER.
LOW-LEVEL RIDGING WILL KEEP TEMPS FROM DROPPING VERY MUCH BEHIND THE
FRONT DESPITE A COOLER AIRMASS BUILDING IN. HIGHS WILL BE IN THE 60S
WITH LOWS IN THE 30S/40S.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
VFR.
EXTENDED AVIATION OUTLOOK...LOW PROBABILITIES OF MVFR CONDITIONS
AND SHOWERS WITH THE COLD FRONTAL PASSAGE...MAINLY TUESDAY NIGHT
INTO EARLY WEDNESDAY.
&&
.MARINE...
THE PRESSURE GRADIENT HAS FINALLY RELAXED ENOUGH TO ALLOW THE LONG
STANDING SCA OVER THE OFFSHORE GA WATERS TO BE DROPPED. HIGH
PRESSURE WILL BUILD TO JUST WEST OF THE REGION BY LATER TONIGHT
WITH WINDS AND SEAS EXPECTED TO REMAIN BELOW HIGHLIGHT LEVELS.
SUNDAY THROUGH THURSDAY...BROAD HIGH PRESSURE OVER THE REGION SUNDAY
WILL SHIFT OFFSHORE MONDAY WITH A COLD FRONTAL PASSAGE TUESDAY
NIGHT. HIGH PRESSURE WILL THEN RETURN THROUGH MID WEEK. THE WORST
CONDITIONS LOOK TO OCCUR WEDNESDAY INTO THURSDAY DUE TO THE
TIGHTENING PRESSURE GRADIENT AND SHOT OF COLD AIR ADVECTION.
HOWEVER...CONDITIONS WILL LIKELY REMAIN JUST BELOW ADVISORY
LEVELS...ESPECIALLY ACROSS THE NEARSHORE WATERS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...FROST ADVISORY FROM 1 AM TO 8 AM EST SUNDAY FOR GAZ117-119-139-
141.
FREEZE WARNING FROM 1 AM TO 8 AM EST SUNDAY FOR GAZ116-118-137-
138-140.
SC...FREEZE WARNING FROM 1 AM TO 8 AM EST SUNDAY FOR SCZ048>052.
MARINE...NONE.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
920 PM CST SAT NOV 24 2012
.DISCUSSION...
919 PM CST
NO SIGNIFICANT CHANGES IN THE FORECAST FOR THE REST OF TONIGHT
BESIDES MINOR TWEAKING OF GRIDDED DATA TO FIT WITH CURRENT
CONDITIONS.
WITH THE WARM AIR ADVECTION AND THICKENING CLOUDS AHEAD OF THE
SHORT WAVE TROUGH MOVING EAST-SOUTHEAST OVER NORTHWEST AND
SOUTHWEST MN AS WELL AS NORTHWEST IA THIS EVENING TEMPERATURES
HAVE HELD STEADY OR EVEN RECOVERED UP TO A COUPLE OF DEGREES F AS
THE SOUTH WINDS HAVE PICKED UP A BIT. NIGHTTIME MINIMUMS LIKELY
ALREADY REACHED SOME LOCATIONS WHILE OTHERS FALL OR RISE A DEGREE
OR TWO OVERNIGHT.
BY MID EVENING THE THICKENING MID LEVEL CLOUDS HAD SPREAD OVER ALL
BUT THE FAR SOUTH AND SOUTHEAST PARTS OF THE FORECAST AREA. RADAR
HAS BEEN DETECTING SOME RETURNS OF LATE AS LIFT RESULTING FROM
THE WARM AIR ADVECTION INCREASES. HOWEVER...LOW LEVELS ACROSS
SOUTHERN WI AS WELL AS NORTHERN IL AND NORTHWEST IN ARE DRY AND
ANY METEORS FALLING FROM THESE MID LEVEL CLOUDS HAVE BEEN AND
WILL CONTINUE TO EVAPORATE BEFORE THEY CAN REACH THE SURFACE.
TRS
&&
.PREV DISCUSSION...
234 PM CST
THE FORECAST CHALLENGES FOR TODAY ARE MAINLY TEMPERATURES AS
READINGS LOOK TO WARM LATER THIS EVENING THROUGH THE DAY SUNDAY
THEN A COOL DOWN INTO MONDAY...FOLLOWED BY A WARM-UP WITH WHAT
LOOKS TO POTENTIALLY BE 50S TO END NOVEMBER AND START
METEOROLOGICAL WINTER.
THE STUBBORN CYCLONIC FLOW AND ITS PESKY STRATUS IS ON THE WAY OUT
WITH A SURFACE RIDGE AXIS MOVING QUICKLY OVER THE AREA THIS EVE.
MID-LEVEL WARM AIR ADVECTION CLOUDS ARE ALREADY SPREADING OVER THIS
RIDGE ACROSS WESTERN IL AND SHOULD QUICKLY EXPAND EAST THROUGH THE
EVE. BEFORE THE ARRIVAL OF THESE CLOUDS IN THE HOURS AFTER
SUNSET...EASTERN AREAS SHOULD SEE TEMPERATURE DROPS THROUGH THE
20S GIVEN LIGHT WINDS. A GRADUAL CLIMB IN TEMPERATURES IS THEN
EXPECTED AREA WIDE AS PRESSURE FALLS AND RETURN FLOW SPREAD IN.
TEMPERATURES ARE LIKELY TO CLIMB BACK TO THE UPPER 20S TO MID 30S
BY DAYBREAK ON SUNDAY.
THE WARM AIR ADVECTION CLOUDS TONIGHT ARE ASSOCIATED WITH A STRONG
UPPER LEVEL LOW MOVING EAST ACROSS NORTHERN SASKATCHEWAN AND
MANITOBA...AND MORE SO WITH A RELATED PV ANOMALY AND SHORT WAVE
EXTENDING SOUTHWARD. THIS WILL TRANSLATE INTO WI BY OVERNIGHT AND
ALREADY TO THE EASTERN GREAT LAKES BY SUNDAY MORNING. SUPPORT FOR
UPWARD MOTION DOES SPREAD THIS FAR SOUTH AS REFLECTED IN RAP AND
NAM Q-VECTOR CONVERGENCE FIELDS. HOWEVER...SATURATION AND MID-
LEVEL MOISTURE CONVERGENCE IS BETTER SITUATED TO THE NORTH. THIS
DISJOINT WILL LIKELY KEEP PRECIPITATION TO THE NORTH...THOUGH
FLURRIES COULD GET CLOSE TO THE WI/IL STATE LINE LATER THIS EVE.
THE WARM SECTOR OF THIS CLIPPER-LIKE SYSTEM WILL CONTINUE OVER THE
AREA INTO SUNDAY. THIS HAS OFFERED 40S TO THE WEST OF THE REGION
IN NEBRASKA TODAY...AND ENVISION LOWER TO MID 40S DURING THE DAY
SUNDAY HERE. AS THE COLD FRONT MOVES THROUGH...WINDS WILL TURN
MORE NORTHWEST BY NIGHT AND TEMPERATURES WILL FALL BACK INTO THE
20S FOR LOWS.
TRENDS CONTINUE TO SUPPORT THIS LOW-LEVEL COOL AIR AND RIDGING
PUSH FROM THE NORTH TO EVOLVE THE PRIMARY BAROCLINIC ZONE TO THE
SOUTH OF THE AREA ON MON NIGHT AND TUE...AND THUS KEEP THE
PRIMARY FORCING FOR PRECIPITATION THERE AS WELL. AS THIS UNFOLDS
THOUGH...THERE STILL IS A WINDOW FOR SMALL CHANCES OF LIGHT SNOW
ACROSS THE SOUTHERN FORECAST AREA...MAINLY LATER MONDAY AFTERNOON
AND NIGHT. THE SPREAD IN THE SREF AND GEFS MEMBERS IS NOW LOW OVER
THE AREA...SO CONFIDENCE ON THIS IS FAIRLY HIGH.
BEYOND THIS...TEMPERATURES WILL SLOWLY MODERATE THROUGH MID WEEK
AS UPPER LEVEL RIDGING ACROSS THE WESTERN STATES EASES EAST.
WITH A LARGE CLOSED LOW OFF THE WEST COAST FORECAST CONSISTENTLY
BY GUIDANCE...THERE WILL BE LITTLE PROGRESSION OF MAJOR WEATHER
SYSTEMS. A QUICK MOVING UPPER LEVEL JET MAX AND ASSOCIATED SHORT
WAVE IS SEEN ON THU NIGHT/FRIDAY WITHIN THE SUITE OF LONG RANGE
GUIDANCE. AGAIN THERE CONTINUES TO BE DECENT BUT SHORT-LIVED
DYNAMICS FORECAST WITH THIS. HAVE INCREASED POPS SOME FROM A
PROVIDED GUIDANCE BLEND. TEMPERATURE SPREAD BY DAYS 6 AND 7 IN THE
FORECAST REALLY INCREASES IN GUIDANCE...SO CONFIDENCE
DROPS...HOWEVER GUIDANCE IS FAVORING TEMPERATURES TO BE ABOVE
NORMAL. ONE OF THE REASONS FOR SUCH SPREAD LOOKS TO BE CLOUD
COVER...AS THE DETERMINISTIC GFS DRAGS UP QUITE A BIT OF LOW-LEVEL
JUICE WITH THE THU NIGHT/FRI WAVE THAT MAY BE TOUGH TO SCOUR THIS
TIME OF YEAR.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* WIND SHIFT TO NW SUNDAY AFTERNOON.
BMD
//DISCUSSION...UPDATED 00Z...
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD WITH ONLY
MINOR CONCERN BEING WIND SHIFT ASSOCIATED WITH A WEAK COLD FRONT
THAT WILL PASS ACROSS THE AREA SUNDAY AFTERNOON. THIS
EVENING...SURFACE RIDGING HAS SLID EAST ACROSS THE AREA WITH LIGHT
SOUTHWESTERLY FLOW IN PLACE ACROSS NORTHERN ILLINOIS AND NORTHWEST
INDIANA. LOW PRESSURE LIES OVER MANITOBA WITH A COLD FRONT PUSHING
ACROSS THE DAKOTAS. THIS FRONT WILL MOVE INTO THE WESTERN GREAT
LAKES REGION OVERNIGHT ALLOWING SOUTHWEST WINDS TO INCREASE SLIGHTLY
TO ABOVE 10 KT. A FEW GUSTS INTO THE MID TEENS ARE POSSIBLE. MID AND
HIGH CLOUDS AHEAD OF THIS SYSTEM ARE ALREADY PUSHING INTO THE
REGION. MID AFTERNOON SUNDAY...THIS COLD FRONT IS EXPECTED TO PUSH
ACROSS THE NORTHERN ILLINOIS TERMINALS SHIFTING WINDS TO THE NW.
WITH A STRONG RIDGE IN PLACE ACROSS THE SOUTHERN STATES CUTTING OFF
MOISTURE TO THIS SYSTEM...EXPECT THE FRONT TO PASS THROUGH WITH VFR
CIGS AND NO PRECIPITATION.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...VFR.
TUESDAY...VFR.
WEDNESDAY...VFR.
THURSDAY...CHC RAIN/SNOW THURSDAY NIGHT.
FRIDAY...CHC RAIN.
BMD
&&
.MARINE...
217 PM...A RIDGE OF HIGH PRESSURE WILL PASS ACROSS LAKE MICHIGAN
EARLY THIS EVENING AS LOW PRESSURE OVER SOUTHERN MANITOBA MOVES
EAST ACROSS THE NORTHERN LAKES SUNDAY AND WEAKENS SUNDAY NIGHT.
THE GRADIENT WILL TIGHTEN TONIGHT BETWEEN THE APPROACHING LOW AND
THE WEAKENING RIDGE. WEST WINDS WILL SHIFT SOUTHWESTERLY THIS
EVENING AND STEADILY INCREASE TO 15-25KTS BY LATE EVENING AND
OVERNIGHT. SOME GUSTS TO 30 KTS ARE POSSIBLE ESPECIALLY OVER THE
SOUTHERN PART OF THE LAKE WHERE THE GRADIENT WILL BE TIGHTEST. A
TRAILING COLD FRONT FROM THIS LOW WILL MOVE ACROSS THE LAKE SUNDAY
AFTERNOON SHIFTING WINDS WESTERLY. AS ANOTHER AREA OF HIGH
PRESSURE MOVES SOUTHEAST FROM THE NORTHERN PLAINS SUNDAY NIGHT TO
THE SOUTHERN LAKES AND OHIO VALLEY MONDAY...THE GRADIENT WILL ONCE
AGAIN TIGHTEN WITH NORTHWEST WINDS 20-25KTS EXPECTED. GRADIENT
COULD BE STRONG ENOUGH FOR GUSTS TO 30KTS OVER NORTHERN LAKE
MICHIGAN. AS THIS HIGH SETTLES SOUTH OF THE LAKE ON TUESDAY...
WINDS WILL TURN SOUTHWESTERLY AND SHOULD RAPIDLY STRENGTHEN
TUESDAY AFTERNOON AS ANOTHER LOW MOVES ACROSS ONTARIO AND THE
NORTHERN LAKES WITH 30KTS AGAIN POSSIBLE OVER THE NORTHERN HALF OF
THE LAKE. ANOTHER AREA OF HIGH PRESSURE WILL MOVE ACROSS THE
MIDWEST AND LAKES REGION MID WEEK. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
901 PM CST SAT NOV 24 2012
.DISCUSSION...
234 PM CST
THE FORECAST CHALLENGES FOR TODAY ARE MAINLY TEMPERATURES AS
READINGS LOOK TO WARM LATER THIS EVENING THROUGH THE DAY SUNDAY
THEN A COOL DOWN INTO MONDAY...FOLLOWED BY A WARM-UP WITH WHAT
LOOKS TO POTENTIALLY BE 50S TO END NOVEMBER AND START
METEOROLOGICAL WINTER.
THE STUBBORN CYCLONIC FLOW AND ITS PESKY STRATUS IS ON THE WAY OUT
WITH A SURFACE RIDGE AXIS MOVING QUICKLY OVER THE AREA THIS EVE.
MID-LEVEL WARM AIR ADVECTION CLOUDS ARE ALREADY SPREADING OVER THIS
RIDGE ACROSS WESTERN IL AND SHOULD QUICKLY EXPAND EAST THROUGH THE
EVE. BEFORE THE ARRIVAL OF THESE CLOUDS IN THE HOURS AFTER
SUNSET...EASTERN AREAS SHOULD SEE TEMPERATURE DROPS THROUGH THE
20S GIVEN LIGHT WINDS. A GRADUAL CLIMB IN TEMPERATURES IS THEN
EXPECTED AREA WIDE AS PRESSURE FALLS AND RETURN FLOW SPREAD IN.
TEMPERATURES ARE LIKELY TO CLIMB BACK TO THE UPPER 20S TO MID 30S
BY DAYBREAK ON SUNDAY.
THE WARM AIR ADVECTION CLOUDS TONIGHT ARE ASSOCIATED WITH A STRONG
UPPER LEVEL LOW MOVING EAST ACROSS NORTHERN SASKATCHEWAN AND
MANITOBA...AND MORE SO WITH A RELATED PV ANOMALY AND SHORT WAVE
EXTENDING SOUTHWARD. THIS WILL TRANSLATE INTO WI BY OVERNIGHT AND
ALREADY TO THE EASTERN GREAT LAKES BY SUNDAY MORNING. SUPPORT FOR
UPWARD MOTION DOES SPREAD THIS FAR SOUTH AS REFLECTED IN RAP AND
NAM Q-VECTOR CONVERGENCE FIELDS. HOWEVER...SATURATION AND MID-
LEVEL MOISTURE CONVERGENCE IS BETTER SITUATED TO THE NORTH. THIS
DISJOINT WILL LIKELY KEEP PRECIPITATION TO THE NORTH...THOUGH
FLURRIES COULD GET CLOSE TO THE WI/IL STATE LINE LATER THIS EVE.
THE WARM SECTOR OF THIS CLIPPER-LIKE SYSTEM WILL CONTINUE OVER THE
AREA INTO SUNDAY. THIS HAS OFFERED 40S TO THE WEST OF THE REGION
IN NEBRASKA TODAY...AND ENVISION LOWER TO MID 40S DURING THE DAY
SUNDAY HERE. AS THE COLD FRONT MOVES THROUGH...WINDS WILL TURN
MORE NORTHWEST BY NIGHT AND TEMPERATURES WILL FALL BACK INTO THE
20S FOR LOWS.
TRENDS CONTINUE TO SUPPORT THIS LOW-LEVEL COOL AIR AND RIDGING
PUSH FROM THE NORTH TO EVOLVE THE PRIMARY BAROCLINIC ZONE TO THE
SOUTH OF THE AREA ON MON NIGHT AND TUE...AND THUS KEEP THE
PRIMARY FORCING FOR PRECIPITATION THERE AS WELL. AS THIS UNFOLDS
THOUGH...THERE STILL IS A WINDOW FOR SMALL CHANCES OF LIGHT SNOW
ACROSS THE SOUTHERN FORECAST AREA...MAINLY LATER MONDAY AFTERNOON
AND NIGHT. THE SPREAD IN THE SREF AND GEFS MEMBERS IS NOW LOW OVER
THE AREA...SO CONFIDENCE ON THIS IS FAIRLY HIGH.
BEYOND THIS...TEMPERATURES WILL SLOWLY MODERATE THROUGH MID WEEK
AS UPPER LEVEL RIDGING ACROSS THE WESTERN STATES EASES EAST.
WITH A LARGE CLOSED LOW OFF THE WEST COAST FORECAST CONSISTENTLY
BY GUIDANCE...THERE WILL BE LITTLE PROGRESSION OF MAJOR WEATHER
SYSTEMS. A QUICK MOVING UPPER LEVEL JET MAX AND ASSOCIATED SHORT
WAVE IS SEEN ON THU NIGHT/FRIDAY WITHIN THE SUITE OF LONG RANGE
GUIDANCE. AGAIN THERE CONTINUES TO BE DECENT BUT SHORT-LIVED
DYNAMICS FORECAST WITH THIS. HAVE INCREASED POPS SOME FROM A
PROVIDED GUIDANCE BLEND. TEMPERATURE SPREAD BY DAYS 6 AND 7 IN THE
FORECAST REALLY INCREASES IN GUIDANCE...SO CONFIDENCE
DROPS...HOWEVER GUIDANCE IS FAVORING TEMPERATURES TO BE ABOVE
NORMAL. ONE OF THE REASONS FOR SUCH SPREAD LOOKS TO BE CLOUD
COVER...AS THE DETERMINISTIC GFS DRAGS UP QUITE A BIT OF LOW-LEVEL
JUICE WITH THE THU NIGHT/FRI WAVE THAT MAY BE TOUGH TO SCOUR THIS
TIME OF YEAR.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* WIND SHIFT TO NW SUNDAY AFTERNOON.
BMD
//DISCUSSION...UPDATED 00Z...
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD WITH ONLY
MINOR CONCERN BEING WIND SHIFT ASSOCIATED WITH A WEAK COLD FRONT
THAT WILL PASS ACROSS THE AREA SUNDAY AFTERNOON. THIS
EVENING...SURFACE RIDGING HAS SLID EAST ACROSS THE AREA WITH LIGHT
SOUTHWESTERLY FLOW IN PLACE ACROSS NORTHERN ILLINOIS AND NORTHWEST
INDIANA. LOW PRESSURE LIES OVER MANITOBA WITH A COLD FRONT PUSHING
ACROSS THE DAKOTAS. THIS FRONT WILL MOVE INTO THE WESTERN GREAT
LAKES REGION OVERNIGHT ALLOWING SOUTHWEST WINDS TO INCREASE SLIGHTLY
TO ABOVE 10 KT. A FEW GUSTS INTO THE MID TEENS ARE POSSIBLE. MID AND
HIGH CLOUDS AHEAD OF THIS SYSTEM ARE ALREADY PUSHING INTO THE
REGION. MID AFTERNOON SUNDAY...THIS COLD FRONT IS EXPECTED TO PUSH
ACROSS THE NORTHERN ILLINOIS TERMINALS SHIFTING WINDS TO THE NW.
WITH A STRONG RIDGE IN PLACE ACROSS THE SOUTHERN STATES CUTTING OFF
MOISTURE TO THIS SYSTEM...EXPECT THE FRONT TO PASS THROUGH WITH VFR
CIGS AND NO PRECIPITATION.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...VFR.
TUESDAY...VFR.
WEDNESDAY...VFR.
THURSDAY...CHC RAIN/SNOW THURSDAY NIGHT.
FRIDAY...CHC RAIN.
BMD
&&
.MARINE...
217 PM...A RIDGE OF HIGH PRESSURE WILL PASS ACROSS LAKE MICHIGAN
EARLY THIS EVENING AS LOW PRESSURE OVER SOUTHERN MANITOBA MOVES
EAST ACROSS THE NORTHERN LAKES SUNDAY AND WEAKENS SUNDAY NIGHT.
THE GRADIENT WILL TIGHTEN TONIGHT BETWEEN THE APPROACHING LOW AND
THE WEAKENING RIDGE. WEST WINDS WILL SHIFT SOUTHWESTERLY THIS
EVENING AND STEADILY INCREASE TO 15-25KTS BY LATE EVENING AND
OVERNIGHT. SOME GUSTS TO 30 KTS ARE POSSIBLE ESPECIALLY OVER THE
SOUTHERN PART OF THE LAKE WHERE THE GRADIENT WILL BE TIGHTEST. A
TRAILING COLD FRONT FROM THIS LOW WILL MOVE ACROSS THE LAKE SUNDAY
AFTERNOON SHIFTING WINDS WESTERLY. AS ANOTHER AREA OF HIGH
PRESSURE MOVES SOUTHEAST FROM THE NORTHERN PLAINS SUNDAY NIGHT TO
THE SOUTHERN LAKES AND OHIO VALLEY MONDAY...THE GRADIENT WILL ONCE
AGAIN TIGHTEN WITH NORTHWEST WINDS 20-25KTS EXPECTED. GRADIENT
COULD BE STRONG ENOUGH FOR GUSTS TO 30KTS OVER NORTHERN LAKE
MICHIGAN. AS THIS HIGH SETTLES SOUTH OF THE LAKE ON TUESDAY...
WINDS WILL TURN SOUTHWESTERLY AND SHOULD RAPIDLY STRENGTHEN
TUESDAY AFTERNOON AS ANOTHER LOW MOVES ACROSS ONTARIO AND THE
NORTHERN LAKES WITH 30KTS AGAIN POSSIBLE OVER THE NORTHERN HALF OF
THE LAKE. ANOTHER AREA OF HIGH PRESSURE WILL MOVE ACROSS THE
MIDWEST AND LAKES REGION MID WEEK. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
522 PM CST SAT NOV 24 2012
.DISCUSSION...
234 PM CST
THE FORECAST CHALLENGES FOR TODAY ARE MAINLY TEMPERATURES AS
READINGS LOOK TO WARM LATER THIS EVENING THROUGH THE DAY SUNDAY
THEN A COOL DOWN INTO MONDAY...FOLLOWED BY A WARM-UP WITH WHAT
LOOKS TO POTENTIALLY BE 50S TO END NOVEMBER AND START
METEOROLOGICAL WINTER.
THE STUBBORN CYCLONIC FLOW AND ITS PESKY STRATUS IS ON THE WAY OUT
WITH A SURFACE RIDGE AXIS MOVING QUICKLY OVER THE AREA THIS EVE.
MID-LEVEL WARM AIR ADVECTION CLOUDS ARE ALREADY SPREADING OVER THIS
RIDGE ACROSS WESTERN IL AND SHOULD QUICKLY EXPAND EAST THROUGH THE
EVE. BEFORE THE ARRIVAL OF THESE CLOUDS IN THE HOURS AFTER
SUNSET...EASTERN AREAS SHOULD SEE TEMPERATURE DROPS THROUGH THE
20S GIVEN LIGHT WINDS. A GRADUAL CLIMB IN TEMPERATURES IS THEN
EXPECTED AREA WIDE AS PRESSURE FALLS AND RETURN FLOW SPREAD IN.
TEMPERATURES ARE LIKELY TO CLIMB BACK TO THE UPPER 20S TO MID 30S
BY DAYBREAK ON SUNDAY.
THE WARM AIR ADVECTION CLOUDS TONIGHT ARE ASSOCIATED WITH A STRONG
UPPER LEVEL LOW MOVING EAST ACROSS NORTHERN SASKATCHEWAN AND
MANITOBA...AND MORE SO WITH A RELATED PV ANOMALY AND SHORT WAVE
EXTENDING SOUTHWARD. THIS WILL TRANSLATE INTO WI BY OVERNIGHT AND
ALREADY TO THE EASTERN GREAT LAKES BY SUNDAY MORNING. SUPPORT FOR
UPWARD MOTION DOES SPREAD THIS FAR SOUTH AS REFLECTED IN RAP AND
NAM Q-VECTOR CONVERGENCE FIELDS. HOWEVER...SATURATION AND MID-
LEVEL MOISTURE CONVERGENCE IS BETTER SITUATED TO THE NORTH. THIS
DISJOINT WILL LIKELY KEEP PRECIPITATION TO THE NORTH...THOUGH
FLURRIES COULD GET CLOSE TO THE WI/IL STATE LINE LATER THIS EVE.
THE WARM SECTOR OF THIS CLIPPER-LIKE SYSTEM WILL CONTINUE OVER THE
AREA INTO SUNDAY. THIS HAS OFFERED 40S TO THE WEST OF THE REGION
IN NEBRASKA TODAY...AND ENVISION LOWER TO MID 40S DURING THE DAY
SUNDAY HERE. AS THE COLD FRONT MOVES THROUGH...WINDS WILL TURN
MORE NORTHWEST BY NIGHT AND TEMPERATURES WILL FALL BACK INTO THE
20S FOR LOWS.
TRENDS CONTINUE TO SUPPORT THIS LOW-LEVEL COOL AIR AND RIDGING
PUSH FROM THE NORTH TO EVOLVE THE PRIMARY BAROCLINIC ZONE TO THE
SOUTH OF THE AREA ON MON NIGHT AND TUE...AND THUS KEEP THE
PRIMARY FORCING FOR PRECIPITATION THERE AS WELL. AS THIS UNFOLDS
THOUGH...THERE STILL IS A WINDOW FOR SMALL CHANCES OF LIGHT SNOW
ACROSS THE SOUTHERN FORECAST AREA...MAINLY LATER MONDAY AFTERNOON
AND NIGHT. THE SPREAD IN THE SREF AND GEFS MEMBERS IS NOW LOW OVER
THE AREA...SO CONFIDENCE ON THIS IS FAIRLY HIGH.
BEYOND THIS...TEMPERATURES WILL SLOWLY MODERATE THROUGH MID WEEK
AS UPPER LEVEL RIDGING ACROSS THE WESTERN STATES EASES EAST.
WITH A LARGE CLOSED LOW OFF THE WEST COAST FORECAST CONSISTENTLY
BY GUIDANCE...THERE WILL BE LITTLE PROGRESSION OF MAJOR WEATHER
SYSTEMS. A QUICK MOVING UPPER LEVEL JET MAX AND ASSOCIATED SHORT
WAVE IS SEEN ON THU NIGHT/FRIDAY WITHIN THE SUITE OF LONG RANGE
GUIDANCE. AGAIN THERE CONTINUES TO BE DECENT BUT SHORT-LIVED
DYNAMICS FORECAST WITH THIS. HAVE INCREASED POPS SOME FROM A
PROVIDED GUIDANCE BLEND. TEMPERATURE SPREAD BY DAYS 6 AND 7 IN THE
FORECAST REALLY INCREASES IN GUIDANCE...SO CONFIDENCE
DROPS...HOWEVER GUIDANCE IS FAVORING TEMPERATURES TO BE ABOVE
NORMAL. ONE OF THE REASONS FOR SUCH SPREAD LOOKS TO BE CLOUD
COVER...AS THE DETERMINISTIC GFS DRAGS UP QUITE A BIT OF LOW-LEVEL
JUICE WITH THE THU NIGHT/FRI WAVE THAT MAY BE TOUGH TO SCOUR THIS
TIME OF YEAR.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* WIND SHIFT TO NW SUNDAY AFTERNOON.
BMD
//DISCUSSION...UPDATED 00Z...
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD WITH ONLY
MINOR CONCERN BEING WIND SHIFT ASSOCIATED WITH A WEAK COLD FRONT
THAT WILL PASS ACROSS THE AREA SUNDAY AFTERNOON. THIS
EVENING...SURFACE RIDGING HAS SLID EAST ACROSS THE AREA WITH LIGHT
SOUTHWESTERLY FLOW IN PLACE ACROSS NORTHERN ILLINOIS AND NORTHWEST
INDIANA. LOW PRESSURE LIES OVER MANITOBA WITH A COLD FRONT PUSHING
ACROSS THE DAKOTAS. THIS FRONT WILL MOVE INTO THE WESTERN GREAT
LAKES REGION OVERNIGHT ALLOWING SOUTHWEST WINDS TO INCREASE SLIGHTLY
TO ABOVE 10 KT. A FEW GUSTS INTO THE MID TEENS ARE POSSIBLE. MID AND
HIGH CLOUDS AHEAD OF THIS SYSTEM ARE ALREADY PUSHING INTO THE
REGION. MID AFTERNOON SUNDAY...THIS COLD FRONT IS EXPECTED TO PUSH
ACROSS THE NORTHERN ILLINOIS TERMINALS SHIFTING WINDS TO THE NW.
WITH A STRONG RIDGE IN PLACE ACROSS THE SOUTHERN STATES CUTTING OFF
MOISTURE TO THIS SYSTEM...EXPECT THE FRONT TO PASS THROUGH WITH VFR
CIGS AND NO PRECIPITATION.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...VFR.
TUESDAY...VFR.
WEDNESDAY...VFR.
THURSDAY...CHC RAIN/SNOW THURSDAY NIGHT.
FRIDAY...CHC RAIN.
BMD
&&
.MARINE...
217 PM...A RIDGE OF HIGH PRESSURE WILL PASS ACROSS LAKE MICHIGAN
EARLY THIS EVENING AS LOW PRESSURE OVER SOUTHERN MANITOBA MOVES
EAST ACROSS THE NORTHERN LAKES SUNDAY AND WEAKENS SUNDAY NIGHT.
THE GRADIENT WILL TIGHTEN TONIGHT BETWEEN THE APPROACHING LOW AND
THE WEAKENING RIDGE. WEST WINDS WILL SHIFT SOUTHWESTERLY THIS
EVENING AND STEADILY INCREASE TO 15-25KTS BY LATE EVENING AND
OVERNIGHT. SOME GUSTS TO 30 KTS ARE POSSIBLE ESPECIALLY OVER THE
SOUTHERN PART OF THE LAKE WHERE THE GRADIENT WILL BE TIGHTEST. A
TRAILING COLD FRONT FROM THIS LOW WILL MOVE ACROSS THE LAKE SUNDAY
AFTERNOON SHIFTING WINDS WESTERLY. AS ANOTHER AREA OF HIGH
PRESSURE MOVES SOUTHEAST FROM THE NORTHERN PLAINS SUNDAY NIGHT TO
THE SOUTHERN LAKES AND OHIO VALLEY MONDAY...THE GRADIENT WILL ONCE
AGAIN TIGHTEN WITH NORTHWEST WINDS 20-25KTS EXPECTED. GRADIENT
COULD BE STRONG ENOUGH FOR GUSTS TO 30KTS OVER NORTHERN LAKE
MICHIGAN. AS THIS HIGH SETTLES SOUTH OF THE LAKE ON TUESDAY...
WINDS WILL TURN SOUTHWESTERLY AND SHOULD RAPIDLY STRENGTHEN
TUESDAY AFTERNOON AS ANOTHER LOW MOVES ACROSS ONTARIO AND THE
NORTHERN LAKES WITH 30KTS AGAIN POSSIBLE OVER THE NORTHERN HALF OF
THE LAKE. ANOTHER AREA OF HIGH PRESSURE WILL MOVE ACROSS THE
MIDWEST AND LAKES REGION MID WEEK. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
124 AM CST FRI NOV 23 2012
.UPDATE...PUBLIC WEATHER DISCUSSION.
.SHORT TERM /TONIGHT/...
CLOUDS FOLLOWING SECONDARY STRONG COLD FRONT ADVANCING OVER ENTIRE
AREA FOR THE REMAINDER OF TONIGHT. FLURRIES WILL ACCOMPANY THE COLD
AIR ESPECIALLY NORTH SECTIONS THROUGH NIGHT AND MID MORNING
TOMORROW. STRONG NW WINDS ALSO EXPECTED. /REV
.PREVIOUS EVENING UPDATE SHORT TERM /TONIGHT/...
NO CHANGES TO WIND ADVISORY OVERNIGHT. ISOLATED SITES CONTINUE TO
HIT SUSTAINED AND GUST ADVISORY CRITERIA...30 AND 45 MPH
RESPECTIVELY. AIRMASS WILL REMAIN MIXED OVERNIGHT ESPECIALLY WITH
PASSAGE OF ANOTHER COLD ADVECTION MAX AFTER 06Z ASSOCIATED WITH
SECONDARY FRONT CURRENTLY DEPICTED FROM SD INTO MN. 01Z RAP 0-500M
LAYER WINDS REMAIN FAIRLY STEADY...BUT INCREASING SLIGHTLY 06Z-13Z.
&&
.AFTERNOON SHORT TERM /TONIGHT/...
A STRONG COLD FRONT IS PLOWING ACROSS IOWA FROM NORTHWEST TO
SOUTHEAST. THE WIND SHIFT HAS JUST PASSED THROUGH GRINNELL AND
CHARITON...AND WILL REACH OTTUMWA AND THE REST OF OUR SOUTHEASTERN
COUNTIES WITHIN THE NEXT COUPLE OF HOURS. HOWEVER...THE STRONGER
WINDS AND COLDER AIR ARE DELAYED A COUPLE OF COUNTIES BEHIND THE
WIND SHIFT...WITH TEMPERATURES ALREADY FALLING PRECIPITOUSLY ACROSS
OUR NORTHERN AREAS. LOW CLOUDS HAVE ALSO SPREAD INTO NORTHERN
IOWA...BUT FURTHER SOUTH SKIES ARE MOSTLY CLEAR.
THE AFOREMENTIONED TEMPERATURE...CLOUD...AND WIND FIELDS NECESSITATE
A PRE FIRST PERIOD IN THE AFTERNOON FORECAST ISSUANCE. WINDS SHOULD
DECREASE A LITTLE BIT WITH SUNSET AS MIXING DIMINISHES...HOWEVER
ANOTHER SHORTWAVE MOVING AROUND THE 500 MB LOW WILL TRANSLATE AT THE
SURFACE INTO AN EFFECTIVE REINFORCING COOL FRONT SWEEPING ACROSS THE
AREA OVERNIGHT. THIS FEATURE SHOULD ENTER OUR NORTHWEST A LITTLE
BEFORE MIDNIGHT AND CROSS THE AREA BEFORE SUNRISE...ACCOMPANIED BY A
SECOND WIND SURGE AND ADDITIONAL LOW CLOUDS. AT THIS TIME IT APPEARS
BASED ON FORECAST SOUNDINGS THAT THE STRATUS LAYER WILL BE FAIRLY
SHALLOW AND WITH NOT MUCH LIFT IN THE LAYER...SO HAVE LEFT FLURRIES
OUT OF THE FORECAST. OF GREATER CONCERN IS WHETHER OR NOT THE SECOND
WIND SURGE WILL ALLOW SPEEDS OR GUSTS TO REACH ADVISORY CRITERIA
OVERNIGHT. THERE APPEARS TO BE A GOOD POSSIBILITY OF THIS AND WITH
THE ADVISORY ALREADY IN EFFECT...HAVE OPTED NOT TO MAKE ANY CHANGES
TO THE HAZARD/HEADLINE AT THIS TIME. IN ANY EVENT WINDY CONDITIONS
WILL PERSIST THROUGH THE NIGHT AND INTO THE MORNING WITH RAPIDLY
FALLING TEMPERATURES AFTER SUNSET. WENT WITH A NON DIURNAL CURVE IN
AN ATTEMPT TO APPROXIMATE THE EFFECTS OF THE STRONG COLD AIR
ADVECTION BEHIND THE FRONT THIS EVENING AND WITH THE SECOND PUSH
OVERNIGHT.
.LONG TERM /FRIDAY THROUGH THURSDAY/...
LOW LEVEL COLD ADVECTION WILL CONTINUE TO PREVAIL ON FRIDAY LEADING
TO A COLD AND BLUSTERY DAY. HIGH TEMPERATURES WILL RANGE FROM THE
UPPER 20S NORTH TO THE MID TO UPPER 30S SOUTH. A WELL MIXED BOUNDARY
LAYER TO NEAR 875 MB WILL KEEP BREEZY TO GUSTY NORTHWEST WINDS IN
PLACE. THE WINDS COMBINED WITH THE TEMPERATURES WILL RESULT IN
APPARENT TEMPERATURE VALUES IN THE SINGLE DIGITS TO TEENS NORTH AND
TEENS TO MID 20S SOUTH. STRATUS DECK IS EXPECTED OVER THE NORTHEAST
TO BEGIN THE DAY BEFORE DIMINISHING THROUGH THE DAY. RIDGE OF HIGH
PRESSURE WILL MOVE INTO CENTRAL IOWA FRIDAY NIGHT WITH WINDS
DROPPING OFF. CLOUD COVER SHOULD INCREASE ACROSS THE WEST WITH MID
LEVEL THETA-E ADVECTION DEVELOPING. THE INCREASING MID LEVEL
TEMPERATURES WILL ENHANCE THE LOW LEVEL VERSION. THE STEEP INVERSION
AND DIMINISHING WINDS SHOULD LEAD TEMPERATURES WELL INTO THE TEENS.
CERTAINLY DEPENDENT ON CLOUDS AND HOW QUICKLY THEY MOVE IN. THE
STRONG LOW LEVEL INVERSION WILL CONTINUE ON SATURDAY AND WILL TEMPER
THE POTENTIAL FOR WARMING ON SATURDAY DESPITE RETURN SOUTHERLY FLOW.
HIGHS WILL RANGE FROM THE MID 30S TO LOWER 40S THE A LITTLE WARMER
ON SUNDAY.
A SHORT WAVE WILL DROP DOWN THROUGH THE NORTHWEST FLOW SUNDAY NIGHT
AND FOLLOWED BY ANOTHER MONDAY NIGHT AND TUESDAY. THIS WILL HELP
DRIVE COLDER AIR BACK INTO THE STATE. THE GEM REMAINS AN OVERLY
AGGRESSIVE OUTLIER DURING THE PERIOD COMBINING THE TWO WAVES AND
DEVELOPING A LOW PRESSURE SYSTEM THROUGH MISSOURI AND SOUTHERN
ILLINOIS WITH POTENTIAL OF MODERATE SNOWFALL THROUGH THE STATE.
STILL A VERY UNLIKELY SCENARIO WITH CANADIAN HIGH PRESSURE DROPPING
INTO THE UPPER MIDWEST AND SUPPRESSING THE SYSTEM WELL TO THE SOUTH.
POSSIBLE TO HAVE LIGHT RAIN OR SNOW WITH THE FRONTAL PASSAGE ON
MONDAY AND MONDAY NIGHT AND HAVE MAINTAINED LOW POPS. HIGH PRESSURE
WILL PREVAIL THROUGH THE REMAINDER OF THE EXTENDED WITH NEAR TO
BELOW CLIMATOLOGY TEMPERATURES AND NO PRECIPITATION EXPECTED.
&&
.AVIATION...23/06Z
VFR STRATUS COVERS PORTIONS OF NRN IA AT 0530Z WITH MVFR STRATUS
JUST UPSTREAM ACROSS THE MN BORDER. THESE MVFR CIGS ARE EXPECTED TO
AFFECT AT LEAST KFOD/KMCW/KALO INTO FRI MORNING. POTENTIAL IS THERE
FARTHER SOUTH TOO...BUT CONFIDENCE NOT GREAT ENOUGH TO INCLUDE AS OF
YET. A SECONDARY PUSH OF COLD AIR AND MIXING...ESSENTIALLY
COINCIDENT WITH THE MVFR CIGS...WILL BOOST GUSTS ONCE AGAIN EARLY
FRI MORNING WITH GUSTS OVER 30KTS NORTH. MVFR CIGS SHOULD EXIT BY
LATE FRI MORNING FOLLOWED BY VERY GRADUALLY DECREASING WINDS INTO
THE AFTERNOON...AND EVENTUALLY SHARPER DECOUPLING BY SUNSET.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY THROUGH 6 AM CST FRIDAY FOR CALHOUN-CERRO GORDO-EMMET-
HANCOCK-HUMBOLDT-KOSSUTH-PALO ALTO-POCAHONTAS-SAC-WEBSTER-WINNEBAGO-
WORTH-WRIGHT
&&
$$
UPDATE PUBLIC DISCUSSION...REV
AVIATION...SMALL
SHORT TERM...LEE
LONG TERM...DONAVON
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1134 PM CST THU NOV 22 2012
.UPDATE...
ADDED 06Z TAF DISCUSSION.
NO CHANGES TO WIND ADVISORY OVERNIGHT. ISOLATED SITES CONTINUE TO
HIT SUSTAINED AND GUST ADVISORY CRITERIA...30 AND 45 MPH
RESPECTIVELY. AIRMASS WILL REMAIN MIXED OVERNIGHT ESPECIALLY WITH
PASSAGE OF ANOTHER COLD ADVECTION MAX AFTER 06Z ASSOCIATED WITH
SECONDARY FRONT CURRENTLY DEPICTED FROM SD INTO MN. 01Z RAP 0-500M
LAYER WINDS REMAIN FAIRLY STEADY...BUT INCREASING SLIGHTLY 06Z-13Z.
&&
.SHORT TERM /TONIGHT/...
A STRONG COLD FRONT IS PLOWING ACROSS IOWA FROM NORTHWEST TO
SOUTHEAST. THE WIND SHIFT HAS JUST PASSED THROUGH GRINNELL AND
CHARITON...AND WILL REACH OTTUMWA AND THE REST OF OUR SOUTHEASTERN
COUNTIES WITHIN THE NEXT COUPLE OF HOURS. HOWEVER...THE STRONGER
WINDS AND COLDER AIR ARE DELAYED A COUPLE OF COUNTIES BEHIND THE
WIND SHIFT...WITH TEMPERATURES ALREADY FALLING PRECIPITOUSLY ACROSS
OUR NORTHERN AREAS. LOW CLOUDS HAVE ALSO SPREAD INTO NORTHERN
IOWA...BUT FURTHER SOUTH SKIES ARE MOSTLY CLEAR.
THE AFOREMENTIONED TEMPERATURE...CLOUD...AND WIND FIELDS NECESSITATE
A PRE FIRST PERIOD IN THE AFTERNOON FORECAST ISSUANCE. WINDS SHOULD
DECREASE A LITTLE BIT WITH SUNSET AS MIXING DIMINISHES...HOWEVER
ANOTHER SHORTWAVE MOVING AROUND THE 500 MB LOW WILL TRANSLATE AT THE
SURFACE INTO AN EFFECTIVE REINFORCING COOL FRONT SWEEPING ACROSS THE
AREA OVERNIGHT. THIS FEATURE SHOULD ENTER OUR NORTHWEST A LITTLE
BEFORE MIDNIGHT AND CROSS THE AREA BEFORE SUNRISE...ACCOMPANIED BY A
SECOND WIND SURGE AND ADDITIONAL LOW CLOUDS. AT THIS TIME IT APPEARS
BASED ON FORECAST SOUNDINGS THAT THE STRATUS LAYER WILL BE FAIRLY
SHALLOW AND WITH NOT MUCH LIFT IN THE LAYER...SO HAVE LEFT FLURRIES
OUT OF THE FORECAST. OF GREATER CONCERN IS WHETHER OR NOT THE SECOND
WIND SURGE WILL ALLOW SPEEDS OR GUSTS TO REACH ADVISORY CRITERIA
OVERNIGHT. THERE APPEARS TO BE A GOOD POSSIBILITY OF THIS AND WITH
THE ADVISORY ALREADY IN EFFECT...HAVE OPTED NOT TO MAKE ANY CHANGES
TO THE HAZARD/HEADLINE AT THIS TIME. IN ANY EVENT WINDY CONDITIONS
WILL PERSIST THROUGH THE NIGHT AND INTO THE MORNING WITH RAPIDLY
FALLING TEMPERATURES AFTER SUNSET. WENT WITH A NON DIURNAL CURVE IN
AN ATTEMPT TO APPROXIMATE THE EFFECTS OF THE STRONG COLD AIR
ADVECTION BEHIND THE FRONT THIS EVENING AND WITH THE SECOND PUSH
OVERNIGHT.
.LONG TERM /FRIDAY THROUGH THURSDAY/...
LOW LEVEL COLD ADVECTION WILL CONTINUE TO PREVAIL ON FRIDAY LEADING
TO A COLD AND BLUSTERY DAY. HIGH TEMPERATURES WILL RANGE FROM THE
UPPER 20S NORTH TO THE MID TO UPPER 30S SOUTH. A WELL MIXED BOUNDARY
LAYER TO NEAR 875 MB WILL KEEP BREEZY TO GUSTY NORTHWEST WINDS IN
PLACE. THE WINDS COMBINED WITH THE TEMPERATURES WILL RESULT IN
APPARENT TEMPERATURE VALUES IN THE SINGLE DIGITS TO TEENS NORTH AND
TEENS TO MID 20S SOUTH. STRATUS DECK IS EXPECTED OVER THE NORTHEAST
TO BEGIN THE DAY BEFORE DIMINISHING THROUGH THE DAY. RIDGE OF HIGH
PRESSURE WILL MOVE INTO CENTRAL IOWA FRIDAY NIGHT WITH WINDS
DROPPING OFF. CLOUD COVER SHOULD INCREASE ACROSS THE WEST WITH MID
LEVEL THETA-E ADVECTION DEVELOPING. THE INCREASING MID LEVEL
TEMPERATURES WILL ENHANCE THE LOW LEVEL VERSION. THE STEEP INVERSION
AND DIMINISHING WINDS SHOULD LEAD TEMPERATURES WELL INTO THE TEENS.
CERTAINLY DEPENDENT ON CLOUDS AND HOW QUICKLY THEY MOVE IN. THE
STRONG LOW LEVEL INVERSION WILL CONTINUE ON SATURDAY AND WILL TEMPER
THE POTENTIAL FOR WARMING ON SATURDAY DESPITE RETURN SOUTHERLY FLOW.
HIGHS WILL RANGE FROM THE MID 30S TO LOWER 40S THE A LITTLE WARMER
ON SUNDAY.
A SHORT WAVE WILL DROP DOWN THROUGH THE NORTHWEST FLOW SUNDAY NIGHT
AND FOLLOWED BY ANOTHER MONDAY NIGHT AND TUESDAY. THIS WILL HELP
DRIVE COLDER AIR BACK INTO THE STATE. THE GEM REMAINS AN OVERLY
AGGRESSIVE OUTLIER DURING THE PERIOD COMBINING THE TWO WAVES AND
DEVELOPING A LOW PRESSURE SYSTEM THROUGH MISSOURI AND SOUTHERN
ILLINOIS WITH POTENTIAL OF MODERATE SNOWFALL THROUGH THE STATE.
STILL A VERY UNLIKELY SCENARIO WITH CANADIAN HIGH PRESSURE DROPPING
INTO THE UPPER MIDWEST AND SUPPRESSING THE SYSTEM WELL TO THE SOUTH.
POSSIBLE TO HAVE LIGHT RAIN OR SNOW WITH THE FRONTAL PASSAGE ON
MONDAY AND MONDAY NIGHT AND HAVE MAINTAINED LOW POPS. HIGH PRESSURE
WILL PREVAIL THROUGH THE REMAINDER OF THE EXTENDED WITH NEAR TO
BELOW CLIMATOLOGY TEMPERATURES AND NO PRECIPITATION EXPECTED.
&&
.AVIATION...23/06Z
VFR STRATUS COVERS PORTIONS OF NRN IA AT 0530Z WITH MVFR STRATUS
JUST UPSTREAM ACROSS THE MN BORDER. THESE MVFR CIGS ARE EXPECTED TO
AFFECT AT LEAST KFOD/KMCW/KALO INTO FRI MORNING. POTENTIAL IS THERE
FARTHER SOUTH TOO...BUT CONFIDENCE NOT GREAT ENOUGH TO INCLUDE AS OF
YET. A SECONDARY PUSH OF COLD AIR AND MIXING...ESSENTIALLY
COINCIDENT WITH THE MVFR CIGS...WILL BOOST GUSTS ONCE AGAIN EARLY
FRI MORNING WITH GUSTS OVER 30KTS NORTH. MVFR CIGS SHOULD EXIT BY
LATE FRI MORNING FOLLOWED BY VERY GRADUALLY DECREASING WINDS INTO
THE AFTERNOON...AND EVENTUALLY SHARPER DECOUPLING BY SUNSET.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY THROUGH 6 AM CST FRIDAY FOR CALHOUN-CERRO GORDO-EMMET-
HANCOCK-HUMBOLDT-KOSSUTH-PALO ALTO-POCAHONTAS-SAC-WEBSTER-WINNEBAGO-
WORTH-WRIGHT
&&
$$
UPDATE/AVIATION...SMALL
SHORT TERM...LEE
LONG TERM...DONAVON
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
850 PM EST SAT NOV 24 2012
.SYNOPSIS...
FLURRIES WILL SLOWLY DIMINISH OVERNIGHT. TEMPERATURES WILL REMAIN
BELOW NORMAL THROUGH THE WEEK...WITH THE NEXT CHANCE FOR SNOW
COMING MONDAY NIGHT INTO TUESDAY.
&&
.NEAR TERM /THROUGH SUNDAY/...
INVERSION HEIGHTS PER THE NAM AND RAP ARE ALREADY FALLING OFF THIS
EVENING DOWNWIND OF LAKE ERIE. THEY STARTED OUT ABOVE 8 KFT
EARLIER...AND LOOK TO BE DOWN TOWARD 5 KFT NOW. WHILE INSTABILITY
IS STILL RATHER IMPRESSIVE GIVEN LAKE TEMPERATURES AROUND +7 TO
+8C AND MODEL 850 MB TEMPERATURES AROUND -11C...THE LENGTH OF
FETCH OVER THE LAKE AS WELL AS UPSTREAM ANTECEDENT CONDITIONS
REALLY ARE NOT. SURFACE DEWPOINTS NORTH OF LAKE HURON ARE RUNNING
NEAR 10F...WHILE IS YIELDING DEWPOINT DEPRESSIONS OF 10-20F IN
SOUTHERN ONTARIO. THIS IS JUST A BIT TOO DRY TO GET LAKE EFFECT
HUMMING ALONG WITHOUT MULTI-LAKE FLOW CONDITIONS. AS IT
STANDS...WE NEVER FULLY GOT A MULTI-LAKE CONNECTION BETWEEN LAKE
HURON AND LAKE ERIE TO GET THE BANDING GOING OVER OUR AREA AS THE
LOW LEVEL FLOW COMPONENT WAS A BIT TOO WESTERLY. AS A
RESULT...WHILE WIDESPREAD SNOW SHOWERS DID STILL OCCUR...THE
BANDING THAT FLOWED OVER MORE THAN ONE LAKE REMAINED MAINLY IN
NORTHERN LOWER MICHIGAN (SUPERIOR/MICHIGAN) AND UPSTATE NEW YORK
(HURON/ERIE). AS LOW LEVEL FLOW BACKS AGAIN TONIGHT IN RESPONSE TO
ANOTHER SHORT WAVE DIVING SOUTHWARD AND MODEST WARM ADVECTION AT
850 MB DEVELOPS...THIS SHOULD EVEN BRING THE SNOW SHOWERS AND
FLURRIES WE HAVE AROUND THIS EVENING TO AN END. FRIES
PREVIOUS DISCUSSION ABOUT TOMORROW FOLLOWS...
A SHORTWAVE IS EXPECTED TO SPEED TO THE EAST TOMORROW...RACING
FROM LOWER MICHIGAN IN THE MORNING TO NEW JERSEY IN THE EVENING.
OVER THE LAST FEW DAYS...MODELS HAVE VERY GRADUALLY INTENSIFIED
THE SHORTWAVE IN ADDITION TO BRINGING IT FARTHER TO THE SOUTH.
APPEARS THAT ANY PRECIPITATION ASSOCIATED WITH THE SHORTWAVE WILL
JUST GLANCE THE LOCAL FORECAST AREA...AND ALTHOUGH POPS COME A BIT
FARTHER SOUTH THAN PREVIOUS FORECAST...HAVE NOT GONE MUCH FARTHER
SOUTH THAN INTERSTATE 80. EXPECT SOME MINOR IMPROVEMENT IN HIGH
TEMPERATURES COMPARED TO TODAY WITH SOUTHWESTERLY WINDS AT 10-15
MPH...BUT TEMPERATURES WILL STILL BE SEVERAL DEGREES BELOW NORMAL.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
WEAK HIGH PRESSURE WILL MOVE INTO THE SOUTHEASTERN UNITED
STATES...ALLOWING FOR AT LEAST ONE DAY OF DRY WEATHER FOR ALL
COUNTIES SUNDAY NIGHT INTO MONDAY. MODELS THEN FOLLOW THE HIGH
PRESSURE WITH A CYCLONE...WITH MUCH OF THE PRECIPITATION FALLING
TO THE NORTH OF THE SURFACE LOW. MODELS HAVE BEEN QUITE
INCONSISTENT WITH THE STORM DURING THE LAST COUPLE OF DAYS...AND
THEREFORE HAVE DECIDED NOT TO MAKE ANY MAJOR CHANGES TO THIS
PORTION OF THE FORECAST. MADE SOME SLIGHT TWEAKS WITH TIMING OF
SYSTEM...BUT OTHERWISE WILL KEEP GENERAL FORECAST OF CHANCE
POPS...WITH SOME LIKELY POPS CREEPING INTO THE RIDGES. ANY
PRECIPITATION IS EXPECTED TO START AS SNOW MONDAY NIGHT...WITH
MOST PLACES CHANGING OVER TO RAIN ON TUESDAY. TEMPERATURES WILL
REMAIN BELOW NORMAL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A CHANCE OF A RAIN SNOW MIX OVER MOST OF THE REGION TUESDAY NIGHT
INTO WEDNESDAY AS SURFACE LOW MOVES TOWARD THE UPPER OHIO VALLEY.
THIS SYSTEM THEN MOVES EASTWARD BY WEDNESDAY WITH ANOTHER SHOT OF
NORTHWEST FLOW AGAIN BRINGING THE CHANCE FOR A SHORT PERIOD OF
LAKE EFFECT SNOW FLURRIES AND SHOWERS. THEN BY WEDNESDAY NIGHT DRY
AND CONTINUED SEASONABLE THROUGH SATURDAY.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
A COLD NORTHWESTERLY FLOW OFF OF LAKE ERIE WILL SHIFT TO MORE
WESTERLY BY DAWN. THIS WILL ALLOW FOR ANY LINGERING SNOW SHOWERS TO
TAPER OFF FOR THE MOST PART BY 06Z AND VFR CONDITIONS TO PREVAIL
FOR THE MAJORITY. ANY REMAINING RESTRICTIONS WILL BE LIMITED TO
KFKL/KDUJ...WITH CEILINGS LOWERING TO MVFR OVERNIGHT. IN
ADDITION...VISIBILITIES MAY BRIEFLY DROP TO MVFR WITH LINGERING
SNOW SHOWERS AT KFKL/KDUJ. WESTERLY WINDS AT 5 TO 10 KTS CAN BE
EXPECTED OVERNIGHT.
VFR CEILINGS WILL PREVAIL THROUGH MUCH OF THE DAY SUNDAY WITH A
WEAK DISTURBANCE BRINGING THE CHANCE OF SNOW SHOWERS TO KFKL FROM
THE LATE MORNING INTO THE EARLY AFTERNOON. WINDS WILL BE
SOUTHWESTERLY AT AROUND 10 KTS AND GUST TO 20 KTS AT TIMES IN THE
LATE MORNING TO EARLY AFTERNOON.
.OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/...
VFR CONDITIONS WILL PREVAIL FOR THE MAJORITY SUNDAY NIGHT THROUGH
MONDAY AS HIGH PRESSURE CROSSES THE AREA. A LOW PRESSURE SYSTEM
APPROACHING FROM THE SOUTHWEST WILL BRING THE CHANCE OF RAIN AND
SNOW WITH RESTRICTIONS TO THE TERMINALS FOR LATE MONDAY NIGHT
INTO TUESDAY. HIGH PRESSURE WILL THEN BUILD IN FROM THE WEST AND
ALLOW FOR MOSTLY VFR CONDITIONS TO PREVAIL WEDNESDAY INTO THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
706 PM EST SAT NOV 24 2012
.SYNOPSIS...
SNOW CURRENTLY AFFECTING A LARGE PORTION OF THE FORECAST AREA WILL
DIMINISH TONIGHT. TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH THE
WEEK...WITH THE NEXT CHANCE FOR SNOW COMING MONDAY NIGHT INTO
TUESDAY.
&&
.NEAR TERM /THROUGH SUNDAY/...
INVERSION HEIGHTS PER THE NAM AND RAP ARE ALREADY FALLING OFF THIS
EVENING DOWNWIND OF LAKE ERIE. THEY STARTED OUT ABOVE 8 KFT
EARLIER...AND SHOULD FALL TOWARD 5 KFT WITHIN THE NEXT FEW HOURS.
WHILE INSTABILITY IS STILL RATHER IMPRESSIVE GIVEN LAKE
TEMPERATURES AROUND +7 TO +8C AND MODEL 850 MB TEMPERATURES AROUND
-11C...THE LENGTH OF FETCH OVER THE LAKE AS WELL AS UPSTREAM
ANTECEDENT CONDITIONS REALLY ARE NOT. BOUNDARY LAYER DEWPOINTS
NORTH OF LAKE HURON ARE RUNNING NEAR 10F...WHILE IS YIELDING
DEWPOINT DEPRESSIONS OF 10-20F IN SOUTHERN ONTARIO. THIS IS JUST A
BIT TOO DRY TO GET LAKE EFFECT HUMMING ALONG WITHOUT MULTI-LAKE
FLOW CONDITIONS. AS IT STANDS...WE NEVER FULLY GOT A MULTI-LAKE
CONNECTION BETWEEN LAKE HURON AND LAKE ERIE TO GET THE BANDING
GOING OVER OUR AREA AS THE LOW LEVEL FLOW COMPONENT WAS A BIT TOO
WESTERLY. AS A RESULT...WHILE WIDESPREAD SNOW SHOWERS DID STILL
OCCUR...THE BANDING THAT FLOWED OVER MORE THAN ONE LAKE REMAINED
MAINLY IN NORTHERN LOWER MICHIGAN (SUPERIOR/MICHIGAN) AND UPSTATE
NEW YORK (HURON/ERIE). AS LOW LEVEL FLOW BACKS AGAIN TONIGHT IN
RESPONSE TO ANOTHER SHORT WAVE DIVING SOUTHWARD...THIS SHOULD EVEN
BRING THE SNOW SHOWERS AND FLURRIES WE HAVE AROUND THIS EVENING TO
AN END.
BECAUSE OF THE AFOREMENTIONED PROBLEMS FOR MODERATE SNOWFALL
ACCUMULATIONS...THE LAKE EFFECT SNOW ADVISORY HAS BEEN DROPPED.
ANY ENHANCED BANDS THAT MAY PERK UP THIS EVENING WILL BE HANDLED
WITH SPECIAL WEATHER STATEMENTS...HOWEVER THE LIKELIHOOD OF
STRONGER BANDS IS DECREASING BY THE HOUR ACROSS THE AREA. FRIES
PREVIOUS DISCUSSION ABOUT TOMORROW FOLLOWS...
A SHORTWAVE IS EXPECTED TO SPEED TO THE EAST TOMORROW...RACING
FROM LOWER MICHIGAN IN THE MORNING TO NEW JERSEY IN THE EVENING.
OVER THE LAST FEW DAYS...MODELS HAVE VERY GRADUALLY INTENSIFIED
THE SHORTWAVE IN ADDITION TO BRINGING IT FARTHER TO THE SOUTH.
APPEARS THAT ANY PRECIPITATION ASSOCIATED WITH THE SHORTWAVE WILL
JUST GLANCE THE LOCAL FORECAST AREA...AND ALTHOUGH POPS COME A BIT
FARTHER SOUTH THAN PREVIOUS FORECAST...HAVE NOT GONE MUCH FARTHER
SOUTH THAN INTERSTATE 80. EXPECT SOME MINOR IMPROVEMENT IN HIGH
TEMPERATURES COMPARED TO TODAY WITH SOUTHWESTERLY WINDS AT 10-15
MPH...BUT TEMPERATURES WILL STILL BE SEVERAL DEGREES BELOW NORMAL.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
WEAK HIGH PRESSURE WILL MOVE INTO THE SOUTHEASTERN UNITED
STATES...ALLOWING FOR AT LEAST ONE DAY OF DRY WEATHER FOR ALL
COUNTIES SUNDAY NIGHT INTO MONDAY. MODELS THEN FOLLOW THE HIGH
PRESSURE WITH A CYCLONE...WITH MUCH OF THE PRECIPITATION FALLING
TO THE NORTH OF THE SURFACE LOW. MODELS HAVE BEEN QUITE
INCONSISTENT WITH THE STORM DURING THE LAST COUPLE OF DAYS...AND
THEREFORE HAVE DECIDED NOT TO MAKE ANY MAJOR CHANGES TO THIS
PORTION OF THE FORECAST. MADE SOME SLIGHT TWEAKS WITH TIMING OF
SYSTEM...BUT OTHERWISE WILL KEEP GENERAL FORECAST OF CHANCE
POPS...WITH SOME LIKELY POPS CREEPING INTO THE RIDGES. ANY
PRECIPITATION IS EXPECTED TO START AS SNOW MONDAY NIGHT...WITH
MOST PLACES CHANGING OVER TO RAIN ON TUESDAY. TEMPERATURES WILL
REMAIN BELOW NORMAL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A CHANCE OF A RAIN SNOW MIX OVER MOST OF THE REGION TUESDAY NIGHT
INTO WEDNESDAY AS SURFACE LOW MOVES TOWARD THE UPPER OHIO VALLEY.
THIS SYSTEM THEN MOVES EASTWARD BY WEDNESDAY WITH ANOTHER SHOT OF
NORTHWEST FLOW AGAIN BRINGING THE CHANCE FOR A SHORT PERIOD OF
LAKE EFFECT SNOW FLURRIES AND SHOWERS. THEN BY WEDNESDAY NIGHT DRY
AND CONTINUED SEASONABLE THROUGH SATURDAY.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
A COLD NORTHWESTERLY FLOW OFF OF LAKE ERIE WILL SHIFT TO MORE
WESTERLY BY DAWN. THIS WILL ALLOW FOR ANY LINGERING SNOW SHOWERS TO
TAPER OFF FOR THE MOST PART BY 06Z AND VFR CONDITIONS TO PREVAIL
FOR THE MAJORITY. ANY REMAINING RESTRICTIONS WILL BE LIMITED TO
KFKL/KDUJ...WITH CEILINGS LOWERING TO MVFR OVERNIGHT. IN
ADDITION...VISIBILITIES MAY BRIEFLY DROP TO MVFR WITH LINGERING
SNOW SHOWERS AT KFKL/KDUJ. WESTERLY WINDS AT 5 TO 10 KTS CAN BE
EXPECTED OVERNIGHT.
VFR CEILINGS WILL PREVAIL THROUGH MUCH OF THE DAY SUNDAY WITH A
WEAK DISTURBANCE BRINGING THE CHANCE OF SNOW SHOWERS TO KFKL FROM
THE LATE MORNING INTO THE EARLY AFTERNOON. WINDS WILL BE
SOUTHWESTERLY AT AROUND 10 KTS AND GUST TO 20 KTS AT TIMES IN THE
LATE MORNING TO EARLY AFTERNOON.
.OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/...
VFR CONDITIONS WILL PREVAIL FOR THE MAJORITY SUNDAY NIGHT THROUGH
MONDAY AS HIGH PRESSURE CROSSES THE AREA. A LOW PRESSURE SYSTEM
APPROACHING FROM THE SOUTHWEST WILL BRING THE CHANCE OF RAIN AND
SNOW WITH RESTRICTIONS TO THE TERMINALS FOR LATE MONDAY NIGHT
INTO TUESDAY. HIGH PRESSURE WILL THEN BUILD IN FROM THE WEST AND
ALLOW FOR MOSTLY VFR CONDITIONS TO PREVAIL WEDNESDAY INTO THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
637 PM EST SAT NOV 24 2012
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 350 PM EST SAT NOV 24 2012
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW NW FLOW ALF OVER
THE GRT LKS BTWN TROF OVER ERN NAMERICA AND A RDG OVER THE ROCKIES.
RIGHT NOW...THERE IS A SHRTWV RDG ALF DOMINATING THE UPR LKS...WITH
SFC HI PRES RDG AXIS STRETCHING FM NOW ONTARIO S INTO THE UPPER
MIDWEST. DESPITE THE APRCH OF THIS RDG AXIS AND LO INVRN BASE SHOWN
ON THE 12Z INL/MPX RAOBS THAT HAS ALLOWED AT LEAST PARTIAL CLEARING
OF LO CLDS OVER MN...THE SC OVER THE CWA HAS BEEN QUITE RESILIENT
WITH H925-85 THERMAL TROF /H85 TEMPS IN THE -12C TO -15C RANGE/
UNDER HIER INVRNS H85-5 AS SHOWN ON THE 12Z GRB/APX RAOBS IN THE
LLVL NW FLOW E OF THE INCOMING SFC HI PRES RDG. THESE LO CLDS ARE
TENDING TO BREAK UP MORE AGGRESSIVELY OVER THE FAR SCENTRAL CWA WITH
DOWNSLOPE NATURE OF THE LLVL FLOW. ALTHOUGH LOWERING SUBSIDENCE
INVRN HAS TENDED TO CAUSE THE LES IN THE CHILLY NW FLOW TO DIMINISH
WITH TIME...THE SHSN HAVE BEEN MOST PERSISTENT NEAR MUNISING WITH
UPSTREAM MOISTENING OFF LK NIPIGON AND MORE LLVL CNVGC ENHANCING THE
LES IN THAT AREA. LOOKING TO THE W...SKIES ARE PCLDY CLOSE TO THE
SFC RDG AXIS...BUT THICKER CLDS ASSOCIATED WITH WAD IN THE SSW FLOW
AHEAD OF ANOTHER SHRTWV NEAR LK WINNIPEG THAT HAS BEEN RIDING OVER
THE ROCKIES RDG ARE MOVING STEADILY TO THE E INTO ERN MN THIS AFTN.
SOME -SN HAS MOVED INTO NW MN THIS AFTN UNDER DEEP ISENTROPIC
ASCENT/SOME UPR DVGC IN THE EXIT REGION OF 120KT H3 JET MAX
SUPPORTING THE SHRTWV.
MAIN FCST CONCERNS THRU SUN INCLUDE TIMING OF SN AND PCPN AMOUNTS
TNGT IN ADVANCE OF CLIPPER TYPE SHRTWV NEAR LK WINNIPEG AND THEN
TRANSITION TO LES ON SUN IN ITS WAKE.
TNGT...AS SFC HI PRES RDG SHIFTS TO THE ERN GRT LKS...EXPECT SW
FLOW/ISENTROPIC ASCENT BTWN DEPARTING RDG AND SHRTWV NEAR LK
WINNIPEG TRACKING TO THE ESE ACRS ONTARIO TO DOMINATE. SINCE THE
MAIN PV ANOMALY WL BE PASSING TO THE N...SHARPER ISENTROPIC ASCENT
BEST SHOWN ON THE 280-290K SFCS /H8-65/ WL BE TRANSIENT AS WARM
CONVEYOR BELT MSTR AXIS SWINGS THRU THE UPR LKS AHEAD OF DRY
SLOTTING ON THE SRN FLANK OF PV ANOMALY TRACK. -SN SHOULD ARRIVE
OVER THE W IN THE EVNG AND PUSH TO ERY AFTER 06Z...WHEN THE PCPN WL
BEGIN TO DIMINISH W-E FOLLOWING THE SHIFT OF THE WARM CONVEYOR BELT
RIBBON TO THE E. PCPN CHCS WL BE ENHANCED BY RIBBON OF H85-7 FGEN...
SOME UPR DVGC IN LEFT EXIT REGION OF H3 JET MAX SUPPORTING THE
ONTARIO SHRTWV...AND SOME DPVA ASSOCIATED WITH ANOTHER SHRTWV
TRACKING THRU THE UPR MIDWEST ON THE SRN FLANK OF THE MAIN PV
ANOMALY. GIVEN FCST H7 SPECIFIC HUMIDITY UP TO 2 G/KG AND A 3-6 HR
PERIOD OF -SN WITH TRANSIENT WARM CONVEYOR BELT/DEEP ASCENT...LOOKS
LIKE 1 TO 2 INCHES OF SN IS LIKELY WITH DECENT OMEGA IN THE DGZ. 12Z
GUIDANCE SHOWS THE SHARPER ISENTROPIC ASCENT/FGEN IMPACTING THE WI
BORDER AREA WITH HIER QPF/SN AMOUNTS ARND 2 INCHES MOST LIKELY
THERE. SOME OF THE MODELS ALSO HINT THERE COULD BE SOME LK
ENHANCEMENT OFF LK MI...BUT THE H925 WINDS LOOK TO BACK TO A MORE
FAVORABLE SW DIRECTION ONLY BRIEFLY TO ALLOW FOR TOO MUCH
ENHANCEMENT AT ISQ-ERY. WITH RELATIVELY QUICK ARRIVAL OF THICKER
CLDS/WAD THIS EVNG...EXPECT NEAR STEADY TEMPS MUCH OF THE NGT AFTER
EARLY MODEST DIURNAL TEMP FALL.
SUN...LINGERING -SN OVER THE E WL END SOON AFTER 12Z FOLLOWING EXIT
OF WARM CONVEYOR BELT MSTR RIBBON TO THE E AND ARRIVAL OF DRY
SLOTTING. HOWEVER...12Z MODELS HAVE TENDED TO DIG THE PV ANOMALY
MORE TO THE ESE OVER NE LK SUP DURING THE DAY. SO AS THE DAY GOES
ON...A COLD CYC NW FLOW WL DVLP IN THE WAKE OF COLD FROPA AS
ASSOCIATED SFC LO SHIFTS TO JUST E OF LK SUP BY 00Z MON. AT THE SAME
TIME...AN AXIS OF SHARPER QVECTOR CNVGC/DPVA AND SOME DEEPER MSTR WL
IMPACT MAINLY THE NE HALF OF THE FA CLOSER TO THE TRACK OF THE
SHRTWV. WITH H85 TEMPS PROGGED TO FALL AS LO AS -15C OVER THE W HALF
OF LK SUP IN THE AFTN...EXPECT MORE WDSPRD LES TO DEVELOP IN THAT
AREA. ALSO BUMPED UP POPS OVER THE NE IN THE AFTN ESPECIALLY NEAR LK
SUP GIVEN FAVORABLE ALIGNMENT OF ONSHORE WNW FLOW...DEEPER MSTR/
DPVA/QVECTOR CNVGC...AND COOLING. THE DAY SHOULD BE DRY OVER THE
SCENTRAL WITH DOWNSLOPE FLOW IN THE ABSENCE OF ANY DYNAMIC
SUPPORT/DEEP MSTR THERE.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 350 PM EST SAT NOV 24 2012
THE MAIN FOCUS IN THE LONG TERM REVOLVES AROUND THE CHANCE FOR
MODERATE LAKE EFFECT SNOW ACCUMULATION EAST NEAR LAKE SUPERIOR
LATE SUNDAY NIGHT THROUGH MONDAY. EXACT LOCATIONS OF THIS POTENTIAL
ARE STILL UNCERTAIN...THOUGH THE MAIN THREAT APPEARS TO BE IN ALGER
COUNTY FROM MUNISING TO GRAND MARAIS AND SOUTH INTO NORTHERN
SCHOOLCRAFT COUNTY. ANOTHER ROUND OF LIGHT SNOW VERY SIMILAR TO
TONIGHTS SYSTEM WILL MOVE THROUGH THE AREA TUESDAY NIGHT. MILDER
PATTERN CHANGES WILL THEN BE IN THE MAKING TOWARD THE END OF THE
WEEK.
SUNDAY NIGHT THROUGH MONDAY NIGHT...THE SHORTWAVE TROUGH ASSOCIATED
WITH THE CLIPPER SYSTEM NOTED IN THE SHORT TERM WILL BE CROSSING
NORTH-CENTRAL LAKE SUPERIOR AND WESTERN UPPER MI AT THE START OF THE
PERIOD. THE ECMWF AND REGIONAL GEM HAVE BEEN QUICKER WITH THE
SHORTWAVE WITH EACH PROGRESSIVE RUN...AND HAVE COME IN LINE WITH THE
GFS AND NAM SOLUTIONS. TRENDS FROM BOTH THE GFS AND ECMWF ARE TO ADD
SUBTLE AMPLIFICATION TO THE WNW FLOW IN THE MID-LEVELS OVER THE
GREAT LAKES...WHILE THE REGIONAL GEM HAS TRENDED TO A LESS AMPLIFIED
FLOW. PREFER THE IDEA PRESENTED BY THE GFS/ECMWF AS THE NICE SHOT OF
CAA BEHIND THE LOW-LEVEL CLIPPER WILL LIKELY ADD SOME AMPLIFICATION
TO THE MID-LEVEL TROUGHING.
LINGERING LIGHT SNOW FROM THE CLIPPER WILL BE ENDING ACROSS THE
EASTERN PORTION OF THE CWA AT 00Z MONDAY AS THE LOW DEPARTS INTO SE
ONTARIO. CAA IMMEDIATELY BEHIND THE SYSTEM IS NOT ALL THAT
IMPRESSIVE...WITH H8 TEMPS ONLY AROUND -10C OVER EASTERN LAKE
SUPERIOR AT 06Z MONDAY. HOWEVER...H8 TEMPS BEGIN TO FALL FOR THE
WESTERN HALF...REACHING -14C BY 06Z MONDAY. AT THE SAME TIME...A
WEAK RIDGE BETWEEN THE DEPARTING TROUGH AND INCOMING AMPLIFYING
TROUGH WILL BE PASSING OVERHEAD AND LIKELY DISRUPT THE LOW-LEVEL
SURFACE FLOW. WHAT MAKES THIS CONCERNING IS THAT SFC TO H8 FLOW FROM
THE NW WOULD PUT A DOMINANT LES BAND INTO FAR EASTERN ALGER COUNTY
BEGINNING SUNDAY EVENING...WHILE A BACKING OF THE FLOW BEHIND THE
SUBTLE RIDGE WOULD TEMPORARILY PUSH THE BAND ALONG THE SHORE. STILL
BEING TWO DAYS OUT...THE CONNECTION BETWEEN THE MID-LEVEL FLOW AND
SFC LES SET-UP IS SOMEWHAT UNCLEAR...BUT WOULD NOT BE SURPRISED IF
THE BAND WOBBLES BETWEEN EASTERN ALGER COUNTY AND NORTHERN LUCE
COUNTY ON EARLY MONDAY MORNING. THEN...THE SECONDARY TROUGH WILL AID
LES INTENSITY ACROSS THE WHOLE NORTH SHORE OF UPPER MI LATER MONDAY
MORNING INTO THE AFTERNOON. THIS WILL OCCUR AS THE BEST CAA AND
COLDEST H8 TEMPS...AROUND -15 TO -16C...WILL BE MOVING OVER THE
LAKE. ADDITIONALLY...LAKE-INDUCED EQUILIBRIUM VALUES BASED OFF OF A
CONSERVATIVE LAKE WATER TEMPERATURE OF 5C WILL BE UPWARDS OF 7KFT
ACROSS THE WEST AND 9KFT FOR THE EAST. FINALLY...THE DGZ WILL BE
LOCATED IN THE HIGHEST 3KFT OF THE CONVECTIVE LAYER IN THE
EAST...LEADING TO THE POTENTIAL FOR INCREASED AGGREGATION FROM
DENDRITES AND THUS HIGHER SNOW RATIOS OF ABOUT 20 TO 1.
THEREFORE...EXPECT THE HIGHEST LES INTENSITY MONDAY MORNING INTO
EARLY AFTERNOON OVER THE EAST NEAR LAKE SUPERIOR.
THE NAM...GEM...AND LOCAL WRF ALL HAVE A DOMINANT BAND WITH
SIGNIFICANT LES FOR CENTRAL ALGER AND NORTHERN SCHOOLCRAFT COUNTY. A
BLEND OF NAM AND LOCAL WRF QPF RESULTED IN ACCUMULATIONS OF 6-10
INCHES CENTERED OVER MELSTRAND. ONLY USED THIS BLEND TO SEE
POTENTIAL AND WILL USE A MORE CONSERVATIVE APPROACH GIVEN THE
UNCERTAINTY OF BAND PLACEMENT. NEEDLESS TO SAY...HEADLINES MAY BE
NEEDED IF HI-RES MODELS REMAIN CONSISTENT WITH LES BAND PLACEMENT.
DRY AIR ADVECTION FROM THE SOUTHWEST IN THE LOW LEVELS...AND H8 WAA
OVERNIGHT MONDAY WILL BEGIN TO ERODE LES FROM WEST TO EAST ACROSS
THE CWA. INVERSION HEIGHTS WILL ALSO CRASH FROM AROUND 9KFT 00Z
TUESDAY TO <5KFT BY 09Z TUESDAY. MEANWHILE WINDS WILL BEGIN BACKING
AND SHOULD PUSH REMAINING LES OFFSHORE...WITH LITTLE ACTIVITY
REMAINING BY TUESDAY MORNING.
TUESDAY THROUGH WEDNESDAY...ANOTHER SHORTWAVE TROUGH DIGGING ESE OUT
OF CANADA WILL IMPACT THE CWA BY TUESDAY AFTERNOON AND BRING A ROUND
OF LIGHT SNOW TO MAINLY THE NORTHERN CWA. THE BEST UPPER LEVEL PV
ANOMALY AND MID-LEVEL Q-VECTOR DIVERGENCE ARE PROGGED TO MOVE
THROUGH TUESDAY AFTERNOON AND EVENING. THE LEFT EXIT OF A 120KT NW
TO SE ORIENTED UPPER JET WILL BE TRACKING ACROSS CENTRAL WI...SO
BEST FEATURES DO NOT QUITE LINE UP. THE LOWEST LEVELS WILL BE DRY
ENOUGH TO THE SOUTH TO PREVENT INITIAL PRECIP FROM REACHING THE
GROUND. DID NOT MAKE MANY CHANGES TO THE PREVIOUS FORECAST OTHER
THAN INCREASE POPS SLIGHTLY FOR THE ENTIRE CWA. THE TROUGH AXIS WILL
THEN PASS THROUGH THE CWA BY 12Z WEDNESDAY AND USHER IN
ANOTHER...YET SHORT-LIVED AND WEAKER...LES EVENT. INVERSION HEIGHTS
COLLAPSE QUITE QUICKLY TO ABOUT 4KFT BY WEDNESDAY AFTERNOON...AND
THE AIR BEHIND THIS SYSTEM IS CONSIDERABLY DRY THROUGHOUT THE
COLUMN. THEREFORE...EXPECTATION IS THAT THERE WILL BE A QUICK LES
EVENT WEDNESDAY MORNING INTO EARLY AFTERNOON FOR THE NW
SNOWBELTS...MAINLY ACROSS THE KEWEENAW PENINSULA AND EAST OF
MUNISING WHERE MOISTURE IS MORE ABUNDANT.
WEDNESDAY NIGHT THROUGH SATURDAY...THE PATTERN TURNS QUIET FOR MUCH
OF THE UPPER GREAT LAKES FOR THE SECOND HALF OF THE WEEK. OTHER THAN
SOME LIGHT LES POSSIBLE EAST NEAR LAKE SUPERIOR ON THURSDAY
NIGHT...NO REAL SIGNIFICANT PRECIP CHANCES PRESENT THEMSELVES AS THE
MAIN ENERGY REMAINS SOUTH OF THE CWA WITH AN UPPER LEVEL DISTURBANCE
MOVING ACROSS THE MID MISSISSIPPI VALLEY ON FRIDAY. THOUGH ON THE
EDGE OF THE FORECAST PERIOD...A STRONG RIDGE WITHIN PACIFIC FLOW
LOOKS TO BRING WELL-ABOVE AVERAGE TEMPS TO BEGIN DECEMBER.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 633 PM EST SAT NOV 24 2012
WITH SFC HIGH PRES RIDGE SHIFTING E OF THE AREA...A BRIEF PERIOD OF
VFR CONDITIONS IS POSSIBLE THIS EVENING. OTHERWISE...ATTENTION TURNS
TO CLIPPER TYPE LOW PRES SYSTEM THAT WILL BRING A PERIOD OF -SN TO
KIWD/KCMX/KSAW LATER THIS EVENING/OVERNIGHT. -SN WILL LIKELY LAST
3-6HRS AT EACH LOCATION. WHILE VIS WILL FLUCTUATE PER UPSTREAM
OBS...IFR VIS SHOULD BE THE PREVAILING CONDITION IN THE -SN. AFTER
THE -SN ENDS W-E OVERNIGHT/EARLY SUN MORNING...EXPECT LINGERING MVFR
CIGS WITH RESIDUAL LOW-LEVEL MOISTURE. ARRIVAL OF COLDER AIR WILL
GENERATE MORE LAKE EFFECT -SHSN SUN MORNING AT KIWD AND ESPECIALLY
AT KCMX WHERE THE EXPECTED W WIND WILL UPSLOPE. ON THE OTHER HAND...
CONDITIONS SUN ARE LIKELY TO TREND TO VFR AT KSAW WITH DOWNSLOPE
WIND COMPONENT.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 350 PM EST SAT NOV 24 2012
EXPECT S-SW WINDS UP TO 20 KTS IN ADVANCE OF A CLIPPER SYSTEM
TONIGHT TO VEER TO THE WNW ON SUN AS THE LO MOVES TO THE E OF LAKE
SUP AND DRAGS A COLD FRONT ACROSS THE AREA.
NORTHWEST WINDS OF 20 TO 30 KNOTS DUE TO HIGH PRESSURE QUICKLY
IMPINGING ON A DEPARTING LOW OVER FAR EASTERN UPPER MICHIGAN WILL BE
POSSIBLE SUNDAY NIGHT...WITH EVEN A FEW GALE FORCE GUSTS UP TO 35
KNOTS NOT OUT OF THE QUESTION. EXPECT THESE WINDS TO QUICKLY
DECREASE ON MONDAY AS A HIGH PRESSURE RIDGE SETTLES OVER THE UPPER
GREAT LAKES. SOUTHWEST WINDS OF 20 TO 25 KNOTS WILL THEN BE
POSSIBLE...MAINLY FOR THE WEST HALF OF LAKE SUPERIOR ON TUESDAY
AHEAD OF A COLD FRONT. ONCE THE FRONT PASSES TUESDAY AFTERNOON AND
EVENING...WINDS WILL VEER TO THE W/NW AND INCREASE TO 20 TO 25 KNOTS
FOR THE EAST HALF OF THE LAKE THROUGH WEDNESDAY. EXPECT WINDS TO
REMAIN BELOW 20 KNOTS FOR THE REMAINDER OF THE PERIOD.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KLUBER
AVIATION...ROLFSON
MARINE...KC/KLUBER
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1055 PM CST THU NOV 22 2012
.AVIATION.../00Z TAF ISSUANCE/
UPPER LOW STILL PROGGED TO MOVE ACROSS THE NORTHERN PORTION OF THE
AREA OVERNIGHT WITH FORCING SHIFTING TO THE NORTHEAST. STILL WILL
LIKELY DROP TO IFR AT TIMES AS THIS UPPER TROUGH MOVES THROUGH.
CONDITIONS SHOULD IMPROVE FROM WEST TO EAST ACROSS AT LEAST MN
PORTION OF THE AREA FRIDAY. WILL GO VFR AROUND 18Z OVER WESTERN
AREAS AND THEN INTO WESTERN WISCONSIN NOT UNTIL FRIDAY EVENING. GFS
APPEARS TO BE A BIT MORE PESSIMISTIC IN HOLDING LOWER LEVEL RH.
WILL HAVE TO MONITOR THIS IN LATER FORECASTS. NORTHWEST WINDS
REMAIN STRONG INTO THE MORNING BEFORE TAPERING BY LATE AFTERNOON.
KMSP...STILL WILL SEE SOME LIGHT SNOW PASS ACROSS THE AREA
OVERNIGHT. LESS THAN ONE HALF INCH ACCUMUALTION. WILL KEEP IT JUST
ABOVE IFR. SLOW CLEARING INTO THE AFTERNOON AS SURFACE RIDGE
APPROACHES FROM THE WEST. WILL SCATTER CLOUDS AFTER 21Z AND
DIMINISH WIND THROUGH 00Z/24.
/OUTLOOK FOR KMSP/
SAT...VFR. WINDS S AT 5-10KTS.
SUN...VFR. WINDS WNW AT 5-10KTS.
MON...MAINLY VFR...POSSIBLE MVFR CIGS LATE WITH -SN. WINDS N 5 KTS.
&&
.PREV DISCUSSION...
/ISSUED 222 PM CST THU NOV 22 2012/
THERE IS ABOUT A 30 DEGREE DIFFERENCE IN THE TEMPERATURE EARLY
THIS AFTERNOON ACROSS THE CWA FROM WEST TO EAST. THE STRONG COLD
FRONT IS NEAR A RICE LAKE-MENOMINEE LINE AND WILL BE EAST OF OUR
CWA BY 22Z. IN THE WAKE OF THE FRONT...NORTHWEST WINDS OF 20 TO 25
MPH WITH GUSTS WELL INTO THE 30 MPH RANGE ARE COMMON. A BAND OF RAIN
AND SNOW EXISTS AS WELL BEHIND THE FRONT FROM SOUTHWEST MN THROUGH
CENTRAL AREAS OF THE STATE AND INTO THE ARROWHEAD. THIS IS AHEAD
OF AN AXIS OF MID LEVEL FRONTOGENESIS ALONG WITH A SUBSTANTIAL PV
BOOT AIMED AT KDLH. WEB CAMS THIS AFTERNOON HAVE INDICATED A QUICK
COATING OF SNOW AS THE BAND MOVES THROUGH.
OUR LOCAL WRF AND THE HRRR HAVE A PRETTY GOOD HANDLE ON THE
PRECIPITATION PATTERN. THE BAND OF FRONTOGENESIS WILL MOVE THROUGH
THE EASTERN MN...INCLUDING THE TWIN CITIES...IN THE 21Z-24Z TIME
FRAME AND ACROSS WEST CENTRAL WI IN THE 00Z-03Z PERIOD. OUR WRF
AND THE HRRR SUGGEST THE BEST CHANCES FOR PRECIPITATION DURING THE
LATE AFTERNOON AND EARLY EVENING HOURS ARE FROM THE NORTH METRO ON
NORTH AND EAST. THIS IS WHERE LIKELY POPS EXIST FOR A TIME WITH
DIMINISHING POPS TO THE SOUTH. A QUICK HALF INCH OF SNOW IS NOT
OUT OF THE QUESTION.
DURING THE LATE EVENING THROUGH OVERNIGHT HOURS...A SECONDARY
TROUGH WILL ROTATE SOUTHEAST ACROSS THE FA. SOME LIGHT SNOW IS
LIKELY...ESPECIALLY OVER OUR FAR NORTHERN TIER OF COUNTIES WITH
PERHAPS A HALF INCH OF SNOW. THEREFORE...RAISED POPS INTO THE LIKELY
CATEGORY FOR THIS AREA WITH CHANCE POPS FOR A FEW ROWS OF COUNTIES
TO THE SOUTH. ADDED FLURRIES ELSEWHERE OVERNIGHT AND FRIDAY
MORNING WITH THE COLD...MOIST...CYCLONIC FLOW.
DEBATED ON WHAT TO DO WITH THE WIND ADVISORY IN EFFECT THROUGH THE
NIGHT. I WOULD PREFER TO SEE AT LEAST A 10 MB PRESSURE GRADIENT
FROM KMSP TO THE SD BORDER. WE ARE CURRENTLY RUNNING AT 8 MB AND
MOST SOLUTIONS KEEP IT THIS WAY THROUGH THE NIGHT. HOWEVER...
EXAMINATION OF THE VERTICAL PROFILES FROM THE NAM THROUGH BUFKIT
INDICATE WEST CENTRAL THROUGH SOUTH CENTRAL MN AS HAVING PRETTY
GOOD POTENTIAL FOR SEEING 30 MPH SUSTAINED WINDS DURING THE
EVENING HOURS. IN ADDITION...TOP OF THE CHANNEL MOMENTUM TRANSFER
INDICATES THE POTENTIAL FOR EAST CENTRAL MN...INCLUDING THE TWIN
CITIES...TO HAVE GUSTS POTENTIAL NEAR 45 MPH DURING THE EVENING AS
WELL. LOOKING AT THE SREF...SEVERAL NMMB MEMBERS WERE BETWEEN 42
AND 45 KNOTS ADDING CONFIDENCE TO THE NAM SOLUTION. EVEN THE
FAVORITE ARW KF MEMBER WAS AT 42 KNOTS. HENCE...WILL NOT MESS WITH
THE ADVISORY AT THIS TIME WITH PLENTY OF POTENTIAL FOR
VERIFICATION OVER THE NEXT 8 TO 12 HOURS.
IT WILL BE BLUSTERY AND COLD OVER THE AREA TOMORROW AS BRISK
NORTHWEST WINDS CONTINUE. HIGHS WILL ONLY BE IN THE 20S. FACTOR IN
THE WIND AND THE APPARENT TEMPERATURE IS ONLY IN THE SINGLE DIGITS
AND TEENS. THERE SHOULD BE SOME FLURRIES AS WELL OVER EASTERN
AREAS IN THE MORNING.
NOTHING TOO EXCITING DURING THE WEEKEND OR NEXT WEEK. HIGH PRESSURE
WILL PASS BY ON SATURDAY WITH A LITTLE MODERATION IN TEMPERATURE
FOR SUNDAY BEFORE ANOTHER COLD FRONT PUSHES THROUGH ON MONDAY.
THERE ARE SOME DIFFERENCES BETWEEN THE GFS/GEM AND THE ECMWF
REGARDING A LOW PRESSURE SYSTEM PASSING SOUTH OF US MONDAY NIGHT
AND TUESDAY. THE GFS/GEM HAVE IT FARTHER NORTH WITH SNOW INTO FAR
SOUTHERN MN WHILE THE ECMWF HAS HIGH PRESSURE OVER IA WITH THE LOW
WAY SOUTHEAST. COLLABORATION WAS TO LEAVE THE SMALL POPS IN THE
FAR SOUTH PART OF MN DUE TO THE DIFFERENCES.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WIND ADVISORY UNTIL 6 AM CST FRIDAY FOR ANOKA-BLUE EARTH-BROWN-
CARVER-CHIPPEWA-DAKOTA-DOUGLAS-FARIBAULT-FREEBORN-GOODHUE-
HENNEPIN-KANDIYOHI-LAC QUI PARLE-LE SUEUR-MARTIN-MCLEOD-
MEEKER-NICOLLET-POPE-RAMSEY-REDWOOD-RENVILLE-RICE-SCOTT-
SHERBURNE-SIBLEY-STEARNS-STEELE-STEVENS-SWIFT-TODD-WASECA-
WASHINGTON-WATONWAN-WRIGHT-YELLOW MEDICINE.
WI...NONE.
&&
$$
RAH/BORGHOFF
AREA FORECAST DISCUSSION
NWS TULSA OK
1042 AM CST FRI NOV 23 2012
.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
VFR CONDITIONS WILL CONTINUE WITH WINDS DIMINISHING AFTER SUNSET.
&&
.PREV DISCUSSION... /ISSUED 939 AM CST FRI NOV 23 2012/
..UPDATE...
DISCUSSION...
TEMP TRENDS HAVE BEEN RUNNING A BIT LOWER THAN FORECAST EARLY THIS
MORNING AND LATEST SHORT TERM HOURLY DATA SUGGESTS TEMPS WILL BE
SLOW TO RISE ESPECIALLY THIS AFTERNOON. GIVEN THE ONGOING STRONG
COLD ADVECTION AND THE POCKET OF SUB ZERO 850MB TEMPS YET TO SLIDE
INTO THE AREA PER LATEST RUC DATA...THIS SLOW WARMING TREND LOOKS
PLAUSIBLE. THIS WILL ALSO LOWER HIGH TEMPS A FEW DEGREES PRIMARILY
NORTH OF INTERSTATE 40. GUSTY WINDS WILL PERSIST THROUGH THE
AFTERNOON.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 52 26 56 38 / 0 0 0 0
FSM 60 27 56 33 / 10 0 0 0
MLC 57 26 59 37 / 10 0 0 0
BVO 49 20 57 32 / 0 0 0 0
FYV 50 21 52 32 / 0 0 0 0
BYV 49 24 50 35 / 0 0 0 0
MKO 54 23 56 34 / 0 0 0 0
MIO 49 22 55 37 / 0 0 0 0
F10 57 26 57 38 / 0 0 0 0
HHW 59 28 57 34 / 10 0 0 0
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
AVIATION...07
AREA FORECAST DISCUSSION
NWS TULSA OK
939 AM CST FRI NOV 23 2012
...UPDATE...
.DISCUSSION...
TEMP TRENDS HAVE BEEN RUNNING A BIT LOWER THAN FORECAST EARLY THIS
MORNING AND LATEST SHORT TERM HOURLY DATA SUGGESTS TEMPS WILL BE
SLOW TO RISE ESPECIALLY THIS AFTERNOON. GIVEN THE ONGOING STRONG
COLD ADVECTION AND THE POCKET OF SUB ZERO 850MB TEMPS YET TO SLIDE
INTO THE AREA PER LATEST RUC DATA...THIS SLOW WARMING TREND LOOKS
PLAUSIBLE. THIS WILL ALSO LOWER HIGH TEMPS A FEW DEGREES PRIMARILY
NORTH OF INTERSTATE 40. GUSTY WINDS WILL PERSIST THROUGH THE
AFTERNOON.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 52 26 56 38 / 0 0 0 0
FSM 60 27 56 33 / 10 0 0 0
MLC 57 26 59 37 / 10 0 0 0
BVO 49 20 57 32 / 0 0 0 0
FYV 50 21 52 32 / 0 0 0 0
BYV 49 24 50 35 / 0 0 0 0
MKO 54 23 56 34 / 0 0 0 0
MIO 49 22 55 37 / 0 0 0 0
F10 57 26 57 38 / 0 0 0 0
HHW 58 28 57 34 / 10 0 0 0
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
SHORT TERM...07
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
933 AM EST FRI NOV 23 2012
.SYNOPSIS...
HIGH PRESSURE WILL WEAKEN AND SHIFT EAST AHEAD OF A COLD FRONT
MOVING THROUGH THE AREA THIS AFTERNOON. THIS FRONT WILL USHER IN
COLDER AIR WHICH WILL LINGER OVER THE WEEKEND. ANOTHER COLD FRONT IS
EXPECTED TO APPROACH THE AREA BY THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 910 AM EST...WATCHING PRECIP WITH FRONT OVER MIDDLE TENNESSEE.
THE SHOWERS HAVE SHOWN A SLIGHT DIMINISHING TREND AS THEY ENTER THE
DRIER AIR OVER THE EASTERN HALF OF THE STATE. LATEST RAP RUN
SUGGESTED THIS WOULD OCCUR THOUGH ITS PLACEMENT OF THE PRECIP IS A
LITTLE TOO FAR WEST. IT DOES SUGGEST SOME UPSLOPE ENHANCEMENT OR
REDEVELOPMENT OVER THE CUMBERLAND PLATEAU AND THEN AS THE FRONT
ENTERS THE SMOKIES...BUT FOLLOWING ITS TRENDS OUR CWFA WOULD SEE A
LATER START TO PRECIP THAN CURRENTLY FCST AND ONLY THE TN BORDER
COUNTIES WOULD BE AFFECTED AT ALL. EXTRAPOLATING THE CURRENT MOTION
ON RADAR WOULD BRING THE PRECIP TO THE BORDER AT ABOUT 18Z. ON THESE
NOTES...DELAYED THE ONSET OF PRECIP BY A COUPLE OF HOURS.
A MAJOR SHORT WAVE TROUGH TRAVERSING THE GREAT LAKES THIS MORNING
WILL INDUCE HEIGHT FALLS ACROSS MUCH OF THE EASTERN CONUS TODAY...
ALLOWING AN ASSOCIATED COLD FRONT TO SWEEP ACROSS OUR AREA THIS
AFTERNOON. THE FRONTAL BAND OF PRECIP MOVING ACROSS THE MISS RIVER
VALLEY EARLY THIS MORNING IS ALREADY FAIRLY MEAGER. IT APPEARS THAT
AS THE SHORT WAVE APPROACHES NEW ENGLAND LATER TODAY...PRE-FRONTAL
FLOW WILL VEER...AND WE WILL LOSE WHAT LITTLE LOW LEVEL FORCING
EXISTS WITH THE FRONT. IN FACT...MODEL QPF PROGS BARELY BRING EVEN
THE LIGHTEST OF PRECIP INTO THE FAR WESTERN MTNS OF NORTH CAROLINA
THIS AFTERNOON. AS SUCH...I/VE BACKED OFF EVER SO SLIGHTLY ON
POPS...FEATURING 40-50 PERCENT IN A NARROW CORRIDOR ALONG THE TENN
BORDER...TAPERING TO ONLY 20 PERCENT NEAR THE SOUTHERN ESCARPMENT OF
THE BLUE RIDGE. A DRY FORECAST WILL BE MAINTAINED IN THE PIEDMONT...
WITH PERHAPS A BRIEF PERIOD OF BKN/OVC MID/HIGH CLOUDS BEING THE
ONLY FANFARE.
THE BIGGER STORY WILL BE THE SHARP DROP IN TEMPS AND RELATIVELY
GUSTY WINDS BEHIND THE FRONT BEGINNING THIS EVENING...ESP ACROSS THE
MTNS. TEMPS WILL DROP QUICKLY INTO THE 40S AFTER SUNSET...WITH MOST
AREAS EXPECTED TO SEE BELOW NORMAL MIN TEMPS BY SUNRISE. WINDS WILL
BE QUITE GUSTY OVER THE MTNS IN THE NW FLOW COLD ADVECTION...BUT
PROGGED PRESSURE GRADIENT AND LOW LEVEL WIND FIELDS SUPPORT SPEEDS
WELL UNDER ADVISORY CRITERIA. THERE WILL BE SHALLOW LOW LEVEL
MOISTURE ALONG THE TENN BORDER IN A MODERATE NW FLOW REGIME WITH
QUICKLY FALLING SNOW LEVELS...SO A FEW HOURS OF FLURRIES OR LIGHT
SNOW SHOWERS WILL BE POSSIBLE...SUPPORTING SLIGHT TO LOW CHANCE
POPS.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AT 230 AM EST FRIDAY...AN UPPER TROUGH WILL BE ALONG THE EAST COAST
ON SATURDAY. AS THIS TROUGH MOVES OFFSHORE...A SOUTHERN STREAM
SHORTWAVE WILL MOVE ACROSS THE SOUTHEAST...LEAVING THE CAROLINA
COAST LATE SATURDAY NIGHT. UPPER FLOW BECOMES ZONAL ON SUNDAY AND
SUNDAY NIGHT...WITH NO SIGNIFICANT UPPER SYSTEM CROSSING OUR AREA.
NW FLOW SNOW SHOWERS WILL DIMINISH IN THE NW NC MOUNTAINS ON
SATURDAY...WHILE A THE SURFACE PRESSURE GRADIENT GRADUALLY RELAXES
OVER OUR AREA. NO SIGNIFICANT SNOW ACCUMULATIONS ARE EXPECTED ALONG
THE NORTHERN TN BORDER SATURDAY. DRY HIGH PRESSURE WILL MOVE OVER
THE SOUTHEAST ON SATURDAY NIGHT AND SUNDAY...WHILE A SURFACE FRONT
STALLS OVER THE OH AND POTOMAC RIVER VALLEYS. ON SUNDAY NIGHT...
SOUTHERLY FLOW ON THE BACK SIDE OF THE HIGH PRESSURE WILL SPREAD
GULF MOISTURE NORTH IN THE MS RIVER VALLEY....BUT OUR AREA WILL
REMAIN DRY. TEMPERATURES WILL START OUT AROUND 10 DEGREES BELOW
NORMAL IN COLD ADVECTION ON SATURDAY AND SATURDAY NIGHT...THEN WILL
WARM TO AROUND 5 DEGREES BELOW NORMAL.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 240 AM FRIDAY...THE MODELS CONTINUE TO SHOW AN UPPER
CONFLUENCE ZONE ACROSS THE SRN M/ATL REGION TO BEGIN THE EXT PERIOD.
AN ASSOCIATED LLVL HIGH CENTER WILL BE SITUATED WELL OFFSHORE BY
THIS TIME ALLOWING A GOOD RETURN FLOW INTO THE CAROLINA REGION. THE
S/LY FLOW WILL BE MAINLY DRY AS DEEPER GOM MOISTURE WILL BE FLUXED
AHEAD OF A DEVELOPING CYCLONE AND SFC FRONT ACROSS THE LOWER MS
VALLEY. A GOOD AMOUNT FALL INSOL WILL HAVE TO COUNTER A LEFTOVER CP
AIRMASS HOWEVER...SO MAX TEMPS SHOULD REACH RIGHT AROUND OR A DEGREE
OR SO BELOW NORMAL. THIS WILL BE THE WARMEST DAY OF THE PERIOD AS
INCREASED CLOUD COVER AND ANOTHER CP SFC HIGH WORKS IN DURING THE
WEEK.
THE GFS AND THE ECMWF DIFFER WITH THE DEEPNESS OF THE UPPER
TROF WITH THE GFS BEING MORE ACUTE AND THUS MORE DYNAMIC WITH THE
UPPER JET AND DIV WHILE THE AXIS CROSSES TO THE NE TUE AFTERNOON.
EXPECT WIDESPREAD CLOUDINESS AND PRECIP DURING FROPA WITH VERY
LIMITED SFC BASED INSTABILITY. SHEAR LEVELS SHOULD BE MODERATE GIVEN
A BLEND OF THE OP MODELS...SO REALLY NOTHING MORE THAN -SHRA IS
EXPECTED BEFORE AND DURING THE BOUNDARY PASSAGE. SOME AREAS OF DIFF
HEATING MAY ALLOW THE FORMATION OF A LOW END QLCS...BUT NOTHING REAL
STRONG OR SEVERE IS PROBABLE AT THIS TIME. A PERIOD OF NW FLOW -SNSH
WILL LIKELY DEVELOP IN WRAP AROUND MOISTURE LATE TUE INTO EARLY
WED...WITH THE NC MTN HIGHER ELEVATIONS ABOVE 3.5 KFT RECEIVING ANY
MEASURABLE...YET SUB/ADVISORY LEVEL SNOWFALL.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
15Z UPDATE...NO SIGNIFICANT CHANGES TO TAFS EXCEPT TO ADD A LOW
END GUST MENTION AT KCLT FOR POTENTIAL TO MIX DOWN STRONGER WINDS
THIS AFTERNOON. MEANWHILE...IN UPSTATE SC...SOME SPORADIC PATCHES
OF LAKE INDUCED FOG OCCURRED EARLY THIS MORNING NEAR KCEU AND
KAND...BRIEFLY CAUSING IFR CONDITIONS AT KCEU. A FEW LOW CLOUDS
MAY HANG OVER THE AREA FOR ANOTHER HOUR OR SO THIS MORNING BUT
OPERATIONAL IMPACTS ARE NOT EXPECTED.
AT KCLT AND ELSEWHERE...VFR CONDITIONS ARE EXPECTED THROUGH THE
PERIOD. SOME PATCHY FOG/LOW STRATUS HAS DEVELOPED NEAR AREA LAKES
THIS MORNING...WITH LIFR CONDITIONS RECENTLY NOTED AT KCEU. KAND
EVEN REPORTED FEW002 BRIEFLY. WE CANNOT RULE OUT A BRIEF PERIOD OF
RESTRICTIONS AT KAND OVER THE NEXT COUPLE OF HOURS...BUT CONFIDENCE
IS LOW ATTM.
A COLD FRONT APPROACHING FROM THE TENNESSEE VALLEY WILL CROSS THE
AREA THIS AFTERNOON. THIS FRONT WILL BE DRY FOR THE VAST MAJORITY OF
THE AREA...ALTHOUGH A FEW SHOWERS WILL BE POSSIBLE THIS AFTERNOON
AND EVENING NEAR THE TENNESSEE BORDER. SOME CLOUD COVER WILL ALSO
ACCOMPANY THE FRONT...BUT THESE SHOULD BE MAINLY OF THE MID AND HIGH
LEVEL VARIETY. CALM WINDS THIS MORNING WILL GIVE WAY TO S/SW WINDS
OF 5-10 KT BY EARLY AFTERNOON. WINDS WILL TURN TOWARD THE WEST AS
THE FRONT CROSSES THE AREA THIS AFTERNOON/EVENING...THEN BECOME NW
BY LATE EVENING. GUSTS IN THE 20S WILL BE POSSIBLE AT KAVL THIS
EVENING AND EVEN THROUGH THE OVERNIGHT.
OUTLOOK...DRY HIGH PRESSURE WILL CONTROL THE WEATHER OVER THE
REGION SATURDAY THROUGH MONDAY. ANOTHER COLD FRONT WILL CROSS THE
REGION ON TUE...POSSIBLY BRINGING FLT RESTRICTIONS AND RAINFALL.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...SBK
NEAR TERM...JDL/WIMBERLEY
SHORT TERM...JAT
LONG TERM...SBK
AVIATION...JDL/WIMBERLEY
AREA FORECAST DISCUSSION...UPDATED
NWS NASHVILLE TN
1131 PM CST THU NOV 22 2012
.UPDATE...FOR 06Z AVIATION DISCUSSION.
&&
.AVIATION...06Z AVIATION DISCUSSION.
BKN VEIL CI TO CONTINUE ACROSS MID STATE EARLY PORTION...WITH
SHORT RANGE MODELS CONTINUING TO SHOW A WEAK FRONTAL PASSAGE
EXPECTED ACROSS MID STATE FROM 23/10Z-23/18Z. SFC WIND SHIFT
LINE STILL LOOKING TO PASS CKV AROUND 23/12Z...BNA AROUND
23/14Z...AND CSV AROUND 23/18Z. STILL LOOKS LIKE FRONTAL PASSAGE
WILL BRING WITH IT ONLY LIGHT PCPN. VFR VSBYS/VFR CEILINGS...HIGH
MVFR CEILINGS CSV...EXPECTED BEFORE FRONTAL PASSAGE. CLRING SKIES
BEHIND FRONTAL PASSAGE. SFC GUSTS TO 20KTS CKV/BNA THRU 24/00Z.
&&
.PREV DISCUSSION.../ISSUED 722 PM CST THU NOV 22 2012/
UPDATE...
BAND OF SHOWERS STRETCHES FROM CENTRAL IL SW THROUGH THE ARKLATEX
REGION. LATEST HRRR DATA STILL SHOWS THE SOLID LINE OF SHOWERS
REACHING INTO THE NW THIRD OF MIDDLE TN BETWEEN MIDNIGHT AND 6
AM...THEN POINTS SW AROUND AND JUST AFTER SUNRISE. FOR THE MOST
PART...MOSTLY CLOUDY SKIES IS CURRENTLY THE RULE ACROSS THE MID
STATE. WILL GO AHEAD AND ADJUST THE SKY GRIDS TOWARD A LITTLE MORE
IN THE WAY OF CLOUDINESS OVERNIGHT. ADDITIONALLY...WILL GO AHEAD
AND EXPAND THE SLIGHT CHANCE OVERNIGHT A LITTLE FURTHER EASTWARD.
WILL BUMP POPS UP SOME AS WELL. REMAINDER OF FCST IN GOOD SHAPE.
PREV DISCUSSION.../ISSUED 552 PM CST THU NOV 22 2012/
UPDATE...FOR 00Z AVIATION DISCUSSION.
AVIATION...00Z AVIATION DISCUSSION.
VEIL OF BKN CI EXPECTED TO CONTINUE ACROSS MID STATE THRU AT LEAST
23/10Z...WITH A WEAK FRONTAL PASSAGE EXPECTED ACROSS THE MID
STATE FROM 23/10Z-23/18Z. SFC WIND SHIFT LINE STILL LOOKING TO
PASS CKV AROUND 23/12Z...BNA AROUND 23/14Z...AND CSV AROUND
23/18Z. FRONTAL PASSAGE WILL BRING WITH IT ONLY LIGHT PCPN.
VFR VSBYS WITH VFR CEILINGS...HIGH MVFR CEILINGS CSV...EXPECTED
BEFORE FRONTAL PASSAGE. CLRING SKIES EXPECTED BEHIND FRONTAL
PASSAGE WITH SFC GUSTS TO 20KTS POSSIBLE CKV/BNA.
PREV DISCUSSION.../ISSUED 234 PM CST THU NOV 22 2012/
DISCUSSION...HIGH PRESSURE STILL HANGING IN ACROSS MIDDLE
TENNESSEE, BUT WILL SLIDE OFF FURTHER TO THE EAST AS A STRONG
COLD FRONT APPROACHES THE MID STATE. FRONT CURRENTLY STRETCHES
FROM THE UPPER MIDWEST INTO THE SOUTHERN PLAINS. WARM AIR PILING
UP AHEAD OF THE FRONT, WITH AFTERNOON TEMPERATURES RUNNING A FEW
DEGREES ABOVE EARLIER FORECAST. LOW-LEVEL AIR REMAINS VERY DRY,
WITH DEW POINT DEPRESSIONS RUNNING CLOSE TO 30 DEGREES. EXPECT
MOISTURE ADVECTION TO INCREASE THIS EVENING AND OVERNIGHT AS THE
PRESSURE GRADIENT STRENGTHENS, WITH SHOWERS CREEPING INTO
NORTHWEST MIDDLE TENNESSEE AFTER MIDNIGHT, AND SCATTERED SHOWERS
SPREADING ACROSS THE MID STATE FRIDAY MORNING. THIS WILL BE A LOW-
QPF EVENT, WITH PRECIPITATION EXPECT TO END BY NOON, THEN MUCH
COLDER AIR MOVING IN FRIDAY EVENING AND EARLY SATURDAY MORNING.
LOOK FOR A QUICK WARM-UP SUNDAY AND MONDAY AS WE GET RETURN FLOW
AHEAD OF THE NEXT ACTIVE SYSTEM.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
31
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1145 PM CST THU NOV 22 2012
.DISCUSSION...
LOOK FOR GUSTY NORTH SURFACE WINDS TO DEVELOP ACROSS WEST CENTRAL
TEXAS DURING THE NEXT 6 HOURS. AVIATION BELOW HAS ADDITIONAL
INFORMATION.
&&
.AVIATION...
THE LATEST RUC SURFACE DATA INDICATE THE COLD FRONT WILL PUSH
SOUTH ACROSS WEST CENTRAL TEXAS DURING THE NEXT 6 HOURS. THE FRONT
IS CURRENTLY LOCATED NEAR A BIG SPRING TO HASKELL LINE. NORTH OF
THE FRONT...METAR DATA INDICATE WINDS ARE GUSTING NEAR 20 KNOTS.
ALSO...THE RUC 925 MB RELATIVE HUMIDITY FIELD INDICATES STRATUS
AND ASSOCIATED MVFR CEILINGS MAY RETURN TO OUR SOUTHERN COUNTIES
AS WE WERE PREVIOUSLY THINKING. SO...I CONTINUED MVFR CEILINGS FOR
THE SONORA AND JUNCTION TERMINALS. FOR TOMORROW...LOOK FOR NORTH
WINDS AROUND 15 KNOTS...WITH POSSIBLE GUSTS RANGING FROM 25 TO 30
KNOTS. AFTER SUNSET TOMORROW EVENING...PLAN FOR NORTH WINDS TO
DIMINISH TO AROUND 10 KNOTS...AS SURFACE HIGH PRESSURE BEGINS TO
BUILD OVER TEXAS.
HUBER
&&
.PREV DISCUSSION... /ISSUED 1013 PM CST THU NOV 22 2012/
DISCUSSION...
MADE ONLY A MINOR ADJUSTMENT TO THE AREA OF SHOWERS TO OUR SOUTH
FOR TONIGHT...PUSHING THEM SLIGHTLY FARTHER SOUTH. EXPECT SHOWERS
TO BE HELD GENERALLY SOUTH OF A LINE FROM SAN SABA TO BARNHART AS
THE FRONT IS MOVING JUST SLIGHTLY FASTER THAN EARLIER MODEL RUNS
HAD PROJECTED. GRIDS ARE PUBLISHED AND TEXT PRODUCTS ARE OUT.
PREV DISCUSSION... /ISSUED 601 PM CST THU NOV 22 2012/
DISCUSSION...
LOOK FOR A STRONG COLD FRONT TO BRING GUSTY NORTH SURFACE WINDS
TO WEST CENTRAL TEXAS LATER TONIGHT. AVIATION BELOW HAS DETAILS.
AVIATION...
ANOTHER STRONG COLD FRONT WILL SWEEP ACROSS WEST CENTRAL TEXAS
TONIGHT AND BRING GUSTY NORTH SURFACE WINDS. THE FRONT...WHICH IS
CURRENTLY IN THE TEXAS PANHANDLE...WILL MOVE INTO THE NORTHERN BIG
COUNTRY AROUND MIDNIGHT. FROM MIDNIGHT THROUGH 12Z...EXPECT
SURFACE WINDS TO RAPIDLY BECOME NORTH...WITH INITIAL GUSTS NEAR 30
KNOTS POSSIBLE. MEANWHILE...STRATUS WILL RETURN TO OUR SOUTHERN
COUNTIES TONIGHT AND BRING MVFR TO AT LEAST SONORA AND JUNCTION.
AS THE FRONT MOVES THROUGH OUR SOUTHERN COUNTIES JUST AFTER
SUNRISE TOMORROW MORNING...CEILINGS WILL LIFT INTO THE VFR RANGE.
IN ADDITION...SOME SHOWERS ARE POSSIBLE WITH THE FRONT...MAINLY
ALONG AND SOUTH OF AN OZONA TO BROWNWOOD LINE. HOWEVER...WITH ONLY
A SLIGHT CHANCE FOR SHOWERS...I DECIDED NOT TO ADD ANY WEATHER TO
ANY OF OUR TERMINALS. DURING THE DAY TOMORROW...PLAN FOR VFR
CONDITIONS...WITH GUSTY NORTH SURFACE WINDS.
HUBER
PREV DISCUSSION... /ISSUED 337 PM CST THU NOV 22 2012/
SHORT TERM...
SHOWERS ACROSS THE BIG COUNTRY HAVE COME TO AN END...WITH REMNANT
MID LEVEL CLOUD COVER AND A SPARSE CU FIELD PRESENT OVER THE EASTERN
HALF OF THE CWA. RAINFALL AMOUNTS LEFT A LITTLE TO BE DESIRED BUT
BIG COUNTRY RESIDENTS CAN BE THANKFUL FOR THE ONE OR TWO HUNDREDTHS
OF AN INCH THAT FELL THIS MORNING. A COLD FRONT IS SITUATED FROM
NEAR CLOVIS /NM/...TO CANADIAN /TX/...TO HUTCHINSON /KS/ AND WILL
CONTINUE SOUTH OVERNIGHT...MAKING ITS WAY THROUGH THE CWA AFTER
MIDNIGHT. AHEAD OF THE FRONT...WE WILL SEE LIGHT SOUTH WINDS AND
CLEAR SKIES. ONCE THE BOUNDARY PASSES...WINDS WILL SHIFT ABRUPTLY TO
THE NORTH AND INCREASE TO 15-20 MPH SUSTAINED...WITH HIGHER GUSTS.
THERE IS A SLIGHT POTENTIAL FOR CONVECTION TO INITIATE ALONG THE
FRONTAL BOUNDARY BUT THIS WOULD LIKELY BE CONFINED TO THE SOUTHERN
HALF OF THE CWA. LOW POPS WERE MAINTAINED THROUGH FRIDAY MORNING
WITH LOW QPF ANTICIPATED. THIS FRONT SHOULD BE THROUGH THE CWA BY
/OR JUST AFTER/ 12Z FRIDAY MORNING AND GUSTY NORTH WINDS OF 15-25
MPH ARE EXPECTED THROUGHOUT MOST OF THE DAY. TEMPS WILL BE ON THE
ORDER OF 15-20 DEGREES COOLER TOMORROW WITH HIGHS FORECAST TO REMAIN
IN THE LOW/MID 60S. ENHANCED MOISTURE ABOVE THE COLD DOME...IN
CONJUNCTION WITH WEAK ISENTROPIC ASCENT...WILL SUPPORT THE FORMATION
OF A STRATO CUMULUS DECK OVER THE CWA AFTER SUNRISE. THIS CLOUD
COVER WILL CLEAR FROM NORTH TO SOUTH AS DRIER AIR ADVECTS INTO THE
AREA BUT SHOULD SERVE TO KEEP TEMPS DOWN A BIT IN THE SOUTHERN
ZONES.
JOHNSON
LONG TERM...
ENOUGH DRY AIR ADVECTION SHOULD ALLOW SKIES TO GRADUALLY CLEAR OVER
OUR SOUTHERN COUNTIES FRIDAY EVENING. WINDS WILL ALSO DIMINISH DURING
THE EVENING AND BECOME LIGHT FRIDAY NIGHT...AS SURFACE HIGH DROPS
SOUTHEAST ACROSS OKLAHOMA WITH A RIDGE EXTENSION SOUTHWEST ACROSS OUR
AREA. THIS SETUP WILL FACILITATE GOOD RADIATIONAL COOLING OVERNIGHT...
AND WE ARE GOING WITH LOWS NEAR THE COLDER MAV GUIDANCE.
A STRONG TEMPERATURE RECOVERY IS IN STORE SATURDAY...AIDED BY ABUNDANT
SUNSHINE WITH SOUTH WINDS DEVELOPING. WARMER STILL FOR SUNDAY WITH
AFTERNOON HIGHS EXPECTED TO BE MOSTLY IN THE MID 70S. SOUTH-SOUTHWEST
WINDS WILL BE INCREASE AND BECOME GUSTY BY SUNDAY WITH LEE SIDE
TROUGHING AND INCREASED SURFACE PRESSURE GRADIENT. TEMPERATURES MONDAY
EXPECTED TO BE 10-15 DEGREES ABOVE NORMAL...AS 850 MB THERMAL RIDGING
SHIFTS ACROSS OUR AREA WITH SOUTHWEST TO WEST LOW-LEVEL FLOW. GIVEN
THIS SETUP...GOING ABOVE GUIDANCE MONDAY WITH HIGHS IN THE UPPER
70S TO NEAR 80 ACROSS OUR CENTRAL AND SOUTHERN COUNTIES. TIMING
OF THE NEXT COLD FRONT COMES INTO PLAY MONDAY. IF THE FRONT ENTERS
THE BIG COUNTRY DURING THE AFTERNOON...COULD RESULT IN COOLER
HIGHS FOR OUR NORTHERN COUNTIES.
THE COLD FRONT WILL PUSH SOUTH THROUGH OUR AREA MONDAY NIGHT...WITH
NORTH WINDS FOLLOWING AND COOLER TEMPERATURES FOR TUESDAY. MODELS
HAVE BEEN TRENDING WEAKER WITH THIS FRONT DURING THE PAST FEW DAYS...
WITH LESS DIGGING OF THE UPPER TROUGH ACROSS THE PLAINS STATES. NOW
APPEARS THAT IT WILL BE MORE OF A PASSING SHOT OF COOLER AIR FOLLOWED
BY A QUICK MODERATION OF TEMPERATURES WEDNESDAY INTO THURSDAY.
19
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 43 62 32 65 44 / 10 0 0 0 0
SAN ANGELO 46 63 32 69 42 / 10 5 0 0 0
JUNCTION 52 62 33 68 39 / 20 20 0 0 0
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
HUBER
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1111 AM CST FRI NOV 23 2012
.AVIATION/18Z TAFS/...993 MILLIBAR SURFACE LOW EAST OF LAKE
SUPERIOR CONTINUES TO PULL AWAY. TIGHT PRESSURE GRADIENT LINGERS
WITH THE GUSTY NW WINDS. FLURRIES STILL HERE AND THERE THOUGH
VSBYS ARE STAYING UP. SOME CLEARING ACTUALLY WORKING IN FROM THE
LAKE AND THIS ALSO IN AN AREA RIGHT BEHIND A 30 UNIT RUC DEFINED
VORT MAX SO ENHANCED SUBSIDENCE IN THAT AREA IS PLAUSIBLE.
STRATUS DECK RIGHT AROUND MVFR THRESHOLDS AND THIS WILL PERSIST
INTO THE EVENING HOURS. SUBSTANTIAL REDUCTION IN 925-850 RH AS THE
NIGHT WEARS ON SO WILL GO WITH SOME CLEARING. HIGH PRESSURE RIDGE
TO BRING CONSIDERABLY LIGHT ER WINDS FOR SATURDAY ALONG WITH MORE
IN THE WAY OF SUNSHINE.
PC
&&
.PREV DISCUSSION... /ISSUED 304 AM CST FRI NOV 23 2012/
TODAY AND TONIGHT...FORECAST CONFIDENCE...HIGH
A VERY STRONG MID LEVEL SHORT WAVE WAS CENTERED OVER NORTHERN
WISCONSIN EARLY THIS MORNING...AND IS EXPECTED TO MOVE NORTH OF LAKE
HURON BY THE NOON HOUR. THE ASSOCIATED SURFACE LOW IS WELL OUT AHEAD
OF THIS UPPER LEVEL FEATURE...BUT TAKING A SIMILAR PATH. SNOW SHOWERS
WITH THE SHORT WAVE WERE OVER EASTERN MN AND NORTHWEST WISCONSIN AND
SHOULD STAY NORTH OF THE FORECAST AREA TODAY. A LARGE LOWER STRATUS
DECK HAS OVERSPREAD THE AREA...REACHING INTO NORTHERN ILLINOIS. WE
COULD SEE A FEW SNOW FLAKES OUT OF THAT...OTHERWISE NOT EXPECTED
ANYTHING MEASURABLE TODAY. IN FACT...ONCE THE SHORT WAVE EXITS TO
THE EAST...THE STRONG SUBSIDENCE IN ITS WAKE MAY START TO PUNCH A
DECENT HOLE IN THE STRATUS RESULTING IN SOME AFTERNOON SUNSHINE.
HOWEVER...THE COLD ADVECTION WILL GIVE US PRETTY STEEP LOW LEVEL
LAPSE RATES THAT MAY OVERRULE THE SUBSIDENCE FOR A TIME AND KEEP THE
CLOUDS LOCKED IN A LITTLE LONGER. WINDS TO REMAIN ELEVATED TODAY
WITH GUSTS TO 30 MPH CONTINUING UNTIL MID AFTERNOON...THAT WILL PUT
WIND CHILLS IN THE UPPER TEENS TO LOWER 20S.
HIGH PRESSURE NUDGES IN TONIGHT. WE SHOULD FINALLY SEE SOME CLEARING
AND THE WINDS WILL DIMINISH. TEMPS TO FALL INTO THE MID TEENS TO LOW
20S.
SATURDAY AND SUNDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH
HIGH PRESSURE WILL BRING SUNNY SKIES SATURDAY...BUT WITH 925 MB
TEMPS OF -5C AT BEST...HIGHS WILL STRUGGLE INTO THE LOW 30S. A WEAK
SHORTWAVE WILL SLIDE THROUGH THE AREA SATURDAY NIGHT...BRINGING
INCREASED CLOUDS ALONG WITH THE POSSIBILITY OF A FEW SNOWFLAKES IN
THE NORTHERN FORECAST AREA. NOT THAT EXCITED ABOUT CHANCES...AS LOW
LEVEL MOISTURE NOT THAT IMPRESSIVE...ALONG WITH PRETTY MARGINAL
LIFT. STILL...ENOUGH DEPTH TO THE SATURATION AND LIFT IN THE NORTH
TO MENTION SLIGHT CHANCE FOR LIGHT SNOW AND ISOLATED FLURRIES.
THE NAM MOVES THE SHORTWAVE THROUGH A BIT LATER THAN OTHER
MODELS...LINGERING THE SNOW CHANCES INTO SUNDAY MORNING. OPTED TO
GO WITH BULK OF OTHER SOLUTIONS...WHICH SUGGEST DRY CONDITIONS BY
SUNDAY MORNING. LOOKS A BIT MILDER SUNDAY...WITH HIGH TEMPS BACK
TOWARD NORMAL FOR LATE NOVEMBER.
MONDAY THROUGH THURSDAY...FORECAST CONFIDENCE...MEDIUM
MODELS HAVE CONTINUED DRIER TREND FOR LOW PRESSURE SYSTEM MONDAY
NIGHT INTO TUESDAY. THE CANADIAN HAD BEEN THE LONE HOLDOUT FOR
KEEPING A DECENT PRECIP EVENT GOING FOR SOUTHERN WISCONSIN...BUT THE
LATEST RUN CAME IN FARTHER SOUTH. KEPT SOME LOW POPS GOING...AS THE
GFS AND CANADIAN STILL BRUSH THE FORECAST AREA WITH SOME LIGHT SNOW.
HIGH PRESSURE IS EXPECTED TO BRING A RETURN OF QUIET WEATHER TO
SOUTHERN WISCONSIN FOR WEDNESDAY AND THURSDAY.
LOOKS LIKE TEMPERATURES WILL BE NEAR TO A COUPLE DEGREES BELOW
NORMAL FOR MUCH OF NEXT WEEK...POSSIBLY MODERATING A BIT BY THE END
OF THE WEEK.
AVIATION/12Z TAFS/...
A LARGE MVFR STATUS DECK COVERS MUCH OF THE GREAT LAKES AND UPPER
MISSISSIPPI VALLEY REGION EARLY THIS MORNING. WE SHOULD START TO SEE
AN EROSION OF THESE CLOUDS FROM WEST TO EAST BY LATE THIS
MORNING...REACHING KMKE BY LATE AFTERNOON OR EARLY EVENING.
WINDS WILL REMAIN STRONG OUT OF THE NORTHWEST THROUGH MUCH OF THE
DAYLIGHT HOURS...FINALLY DIMINISHING WITH SUNSET AND THE ARRIVAL OF
HIGH PRESSURE AND A WEAKER PRESSURE GRADIENT.
MARINE...
A GALE WARNING REMAINS IN EFFECT UNTIL 10 PM THIS EVENING...
THEREAFTER A SMALL CRAFT ADVISORY WILL LIKELY REMAIN IN EFFECT
THROUGH THE MORNING ON SATURDAY. THE STRONG NORTHWEST WINDS TODAY
WILL GRADUALLY DIMINISH BY THE EVENING HOURS AS THE PRESSURE
GRADIENT RELAXES WITH HIGH PRESSURE PUSHING INTO THE REGION.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...GALE WARNING UNTIL 10 PM CST THIS EVENING FOR LMZ643>646.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...DAVIS
SATURDAY THROUGH THURSDAY...DDV
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1257 AM EST SUN NOV 25 2012
.SYNOPSIS...
COOL AND BLUSTERY CONDITIONS ARE EXPECTED FOR THE REMAINDER OF
THE WEEKEND INTO EARLY NEXT WEEK. UNCERTAINTY REMAINS REGARDING
THE TRACK AND INTENSITY OF A STORM TUESDAY AND WEDNESDAY. MUCH
COLDER WEATHER IS EXPECTED BEHIND THE STORM LATE NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
1 AM UPDATE...
ONLY MINOR TWEAKS TO THE FORCAST WITH THIS UPDATE. ADJUSTED SKIES
TOWARD LATEST RAP GUIDANCE WHICH HAS BEEN HANDLING THE STRATO-CU
FROM UPSTREAM. OTHERWISE...ONLY OTHER CHANGES WERE MADE TO BRING
TEMPS/DWPTS UP TO CURRENT TRENDS.
PREVIOUS DISCUSSION...
430 PM UPDATE... WINDS HAVE INCREASED LATE THIS AFTERNOON AS THE
MIXING DEPTH GETS TO NEAR 850 MB. A GUST TO 44 KTS JUST OCCURRED
AT WORCESTER AT 4 PM... WITH 32 KTS WAS REPORTED AT ORANGE MA AND
33 KTS AT PITTSFIELD AT 3 PM. THE NORTHWEST PRESSURE GRADIENT WILL
CONTINUE TO TIGHTEN UP THIS EVENING AND OVERNIGHT IN THE WAKE OF
AN UPPER LEVEL TROUGH SWINGING ACROSS NORTHERN NEW ENGLAND. WINDS
AT 3000-5000 FT OFF THE GROUND ARE FORECAST TO INCREASE TO 40-45
KNOTS OVERNIGHT. IT IS A TRICKY CALL FOR THE WINDS TONIGHT. BUFKIT
SHOWS THAT DESPITE THE COLD AIR ADVECTION...THE WINDS DIMINISH TO
15 KT OVER MOST OF THE INTERIOR AS THE TEMPERATURE DROPS AND THE
MIXING LEVEL IS NOT AS DEEP. A MAJOR EXCEPTION IS ALONG THE
COAST...EVERYWHERE FROM CAPE ANN TO CAPE COD AND ON THE RI
COAST...WHERE IT SHOULD REMAIN GUSTING TO 25 TO 30 KTS OVERNIGHT.
FOR THE MOST PART...LAKE EFFECT SNOW SHOWERS HAVE BEEN CONFINED TO
THE BERKSHIRES. HOWEVER...A LIGHT SPRINKLE WAS REPORTED AT 3 PM IN
NASHUA NH... SO SOME OF THE PRECIPITATION IS HITTING THE GROUND.
CANNOT RULE OUT A FLAKE OF SNOW MAINLY WEST OF THE CONNECTICUT
RIVER THIS EVENING BUT ACTIVITY SHOULD DIMINISH WITH NIGHTFALL.
THE RAP MODEL SHOWS NO PRECIPITATION AFTER 04Z.
LOWS MAINLY IN THE UPPER TEENS TO MID 20S EXCEPT NEAR 30 ALONG THE
IMMEDIATE SOUTH COAST.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
SUNDAY...
SHOULD BE RATHER SIMILAR TO TODAY. SUNSHINE SHOULD GIVE WAY TO A
FAST MOVING BATCH OF MID LEVEL CLOUDINESS IN THE AFTERNOON LEADING
TO PARTLY TO MOSTLY CLOUDY SKIES. USED A 50-50 BLEND OF GFS AND
NAM FOR SKY GRIDS SINCE THEY DIFFERED ON THE TIMING OF THESE CLOUDS.
IT WILL AGAIN BECOME WINDY WITH GUSTS TO 20 TO 30 KTS FROM MID
MORNING THROUGH MID AFTERNOON AS THE MIXING INCREASES. WINDS
SHOULD DIMINISH LATE IN THE AFTERNOON. HIGHS MAINLY IN THE 40S.
SUNDAY NIGHT...
BECOMING MOSTLY CLEAR WITH LIGHT WINDS AND LOWS 20-30.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
* COLDER...DRY WEATHER EXPECTED EARLY NEXT WEEK
* A STORM IS LIKELY TO AFFECT THE AREA MID WEEK
* COLDER WEATHER EXPECTED LATE NEXT WEEK
24/12Z MODELS ARE STARTING TO SHOW SOME CONSISTENCY THROUGHOUT THE
LONG TERM PORTION OF THE FORECAST. THERE IS STILL PLENTY OF
UNCERTAINTY REGARDING THE MID WEEK STORM...THOUGH THE 06Z GFS/00Z
ECMWF/12Z GFS ALL HAVE SIMILAR SOLUTIONS WITH LOW PRESSURE MOVING
OFF THE MID ATLANTIC COAST AND TRAVELING JUST SOUTH OF THE 40/70
BENCHMARK AND BRINGING SNOW TO MUCH OF THE AREA WITH A FOCUS ON THE
SOUTHERN PORTIONS OF SOUTHERN NEW ENGLAND. HOWEVER...THE 12Z NAM
/AN OUTLIER AT THIS POINT/ SIMPLY HAS HIGH PRESSURE OVER THE REGION
AND NO INDICATION OF PRECIP AT ALL. WILL TREND TOWARD A
ECMWF/GFS/HPC SOLUTION... HOWEVER...KEEPING IN MIND ALL THE FLIP
FLOPPING AND UNCERTAINTY WILL ONLY TREND TOWARD IT.
ASIDE FROM THE STORM...THE WEATHER IS FAIRLY QUIET BOTH EARLY AND
LATE NEXT WEEK WITH NORTHWESTERLY FLOW BRINGING COLDER TEMPERATURES.
MONDAY...STRONG NORTHWESTERLY FLOW WILL CONTINUE TO KEEP TEMPS
SLIGHTLY BELOW NORMAL. HIGH PRESSURE BUILDS IN KEEPING MOSTLY CLEAR
SKIES THROUGH THE DAY AND INTO THE EVENING.
TUESDAY INTO WEDNESDAY...GIVEN THE NUMEROUS SOLUTIONS OVER THE LAST
SEVERAL DAYS AM STILL HESITANT TO MAKE A RUN FOR A SINGLE SOLUTION.
THAT SAID...THE ECMWF AND GFS HAVE STARTED TO FOCUS TOWARDS LOW
PRESSURE ON A SOUTHERLY TRACK ALONG OR JUST SOUTH OF THE 40/70
BENCHMARK FOR WINTER STORMS. AT THIS POINT...THIS SOLUTION BRINGS
HEAVY SNOW...LIKELY FOCUSED MORE ON THE SOUTHERN AREAS OF THE CWA
MAINLY ON TUESDAY NIGHT INTO WEDNESDAY. THERE ARE STILL OTHER
SOLUTIONS...THE NAM HAS HIGH PRESSURE OVER THE REGION TUESDAY.
HOWEVER...AT THIS POINT...THE ECMWF/GFS SOLUTION APPEARS THE MOST
LIKELY. WILL TREND TOWARD THIS SOLUTION...BUT CONFIDENCE IS STILL
LOW.
THURSDAY AND FRIDAY...DESPITE ALL THE DISCREPANCIES/UNCERTAINTY FOR
EARLIER IN THE PERIOD...THESE TWO PERIODS HAVE FAIRLY GOOD AGREEMENT
AMONGST THE MODELS. NORTHWESTERLY FLOW WITH THE COOLEST TEMPS OF
THE SEASON THUS FAR MOVING IN ON STRONG COLD AIR ADVECTION. LOOKS
LIKE A COLD AND BRISK END TO THE WEEK.
&&
.AVIATION /05Z SUNDAY THROUGH THURSDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
OVERVIEW...MODERATE TO HIGH CONFIDENCE.
MOSTLY VFR THROUGH MONDAY. AFTER SOME CLEARING THIS MORNING...A
SHORTWAVE WILL LEAD TO INCREASING LOW AND MID CLOUDS THIS
AFTERNOON...BUT CIG HEIGHTS ARE EXPECTED TO REMAIN VFR THRUT.
OTHERWISE...CAN/T RULE OUT SOME LIGHT SNOW SHOWERS PARTICULARLY
TERMINALS NW OF A LINE FROM BDL-ORH-MHT IN THE AFTERNOON AND
EVENING SUN...BUT ONCE AGAIN...SAVE FOR BRIEF REDUCTIONS IN VSBY.
VFR IS EXPECTED TO DOMINATE.
WINDS SLACKEN A BIT WITH GUSTS GENERALLY 15-25 THRUT 06Z-12Z BUT
INCREASE AGAIN WITH W-NW GUSTS 20-30 KT DURING THE DAY SUN. WINDS
THEN SLACKEN OFF SIGNIFICANTLY OVERNIGHT SUN NIGHT.
KBOS TAF...MODERATE TO HIGH CONFIDENCE.
GENERALLY VFR EXPECTED. W-NW WINDS TONIGHT WITH GUSTS 20-25 KT
THROUGH 12Z...25-30 KT DURING THE DAY.
KBDL TAF...HIGH CONFIDENCE.
GENERALLY VFR. CANNOT RULE OUT A BRIEF FLURRY LATE THIS AFTERNOON
AND EVENING. OTHERWISE W-NW WINDS GUSTING TO 20 KT THROUGH
12Z...25-30 KT AFTER 12Z.
OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...
MONDAY...HIGH CONFIDENCE. VFR.
TUESDAY THROUGH WEDNESDAY MORNING...LOW CONFIDENCE. MVFR/IFR
CONDITIONS POSSIBLE IN POTENTIAL RA/SN/FZRA/SNPL.
WEDNESDAY AFTERNOON THROUGH THURSDAY...MODERATE TO HIGH CONFIDENCE.
VFR.
&&
.MARINE...
MODERATE CONFIDENCE INTO SUNDAY NIGHT...
GALE WARNINGS CONTINUE FOR THE COASTAL WATERS INCLUDING NANTUCKET
SOUND...EXCEPT FOR THE INNER HARBORS AND BAYS WHERE SMALL CRAFT
ADVISORIES ARE POSTED. AS AN UPPER LEVEL SHORT WAVE TROUGH SWINGS
THROUGH NORTHERN NEW ENGLAND OVERNIGHT...W TO NW WINDS WILL
CONTINUE TO INCREASE OVER THE COASTAL WATERS...REACHING 35 KTS
OVER THE GALE WARNING AREA AND CONTINUING INTO MUCH OF SUNDAY.
THERE IS A CHANCE THAT A FEW GUSTS TO GALE FORCE COULD OCCUR
CLOSER TO THE COAST IN THE SMALL CRAFT ADVISORY AREA...BUT
FREQUENT GUSTS ARE NOT EXPECTED. ONE CONCERN IS A GUST TO 44 KTS
AT WORCESTER AIRPORT RIGHT AT 4 PM... BUT WE ARE THINKING THAT
THIS IS ELEVATIONAL AND STILL RELATED TO THE MAXIMUM MIXING OF THE
AFTERNOON. WE WILL NEED TO WATCH THIS CLOSELY IN CASE GALES ARE
NEEDED EVERYWHERE ALONG THE COAST OVERNIGHT.
SEAS ARE FORECAST TO CONTINUE TO BUILD TO 8 TO 11 FEET ACROSS THE
OUTER WATERS TONIGHT.
WINDS SHOULD BEGIN TO DIMINISH TO BELOW GALE FORCE IN THE
AFTERNOON BUT SMALL CRAFT ADVISORY LEVEL WIND GUSTS TO 25 KTS MAY
CONTINUE OVER THE OUTER WATERS THROUGH SUNDAY NIGHT. SLOWLY
SUBSIDING SEAS SUNDAY NIGHT.
OUTLOOK...MONDAY THROUGH THURSDAY...
MODERATE CONFIDENCE THROUGH THE PERIOD.
SEAS WILL FALL BELOW 5 FEET LATE MONDAY AND REMAIN BELOW THROUGH
LATE TUESDAY. THEN SEAS WILL BUILD AGAIN AS LOW PRESSURE APPROACHES
THE WATERS LATE TUESDAY INTO WEDNESDAY AND REMAIN ABOVE 5 FEET
THROUGH THE PERIOD. WINDS WILL REMAIN BELOW 25 KTS THROUGH TUESDAY.
WINDS INCREASE TO 25 TO 30 KTS WEDNESDAY AND THURSDAY AS LOW
PRESSURE MOVES ACROSS THE WATERS. LOW PROBABILITY OF GALES LATE
WEDNESDAY INTO THURSDAY.
&&
.FIRE WEATHER...
NO HEADLINES ARE ANTICIPATED BUT FELT IT WAS WORTH MENTIONING THAT
THE MINIMUM RELATIVE HUMIDITIES WILL BE DOWN AROUND 30 PERCENT
SUNDAY AFTERNOON. WINDS WILL BE GUSTING TO 20 TO 30 MPH BUT WILL
BE DIMINISHING IN THE MID TO LATE AFTERNOON AT THE TIME OF THE
MINIMUM HUMIDITIES.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...GALE WARNING UNTIL 10 AM EST THIS MORNING FOR ANZ232>235-237-
256.
SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR ANZ230-
231-236-251.
GALE WARNING UNTIL 1 PM EST THIS AFTERNOON FOR ANZ250-254-255.
&&
$$
SYNOPSIS...RLG/GAF
NEAR TERM...DOODY/RLG/GAF
SHORT TERM...GAF
LONG TERM...RLG
AVIATION...DOODY/RLG
MARINE...RLG/GAF
FIRE WEATHER...
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
302 AM CST SUN NOV 25 2012
.DISCUSSION...
919 PM CST
NO SIGNIFICANT CHANGES IN THE FORECAST FOR THE REST OF TONIGHT
BESIDES MINOR TWEAKING OF GRIDDED DATA TO FIT WITH CURRENT
CONDITIONS.
WITH THE WARM AIR ADVECTION AND THICKENING CLOUDS AHEAD OF THE
SHORT WAVE TROUGH MOVING EAST-SOUTHEAST OVER NORTHWEST AND
SOUTHWEST MN AS WELL AS NORTHWEST IA THIS EVENING TEMPERATURES
HAVE HELD STEADY OR EVEN RECOVERED UP TO A COUPLE OF DEGREES F AS
THE SOUTH WINDS HAVE PICKED UP A BIT. NIGHTTIME MINIMUMS LIKELY
ALREADY REACHED SOME LOCATIONS WHILE OTHERS FALL OR RISE A DEGREE
OR TWO OVERNIGHT.
BY MID EVENING THE THICKENING MID LEVEL CLOUDS HAD SPREAD OVER ALL
BUT THE FAR SOUTH AND SOUTHEAST PARTS OF THE FORECAST AREA. RADAR
HAS BEEN DETECTING SOME RETURNS OF LATE AS LIFT RESULTING FROM
THE WARM AIR ADVECTION INCREASES. HOWEVER...LOW LEVELS ACROSS
SOUTHERN WI AS WELL AS NORTHERN IL AND NORTHWEST IN ARE DRY AND
ANY METEORS FALLING FROM THESE MID LEVEL CLOUDS HAVE BEEN AND
WILL CONTINUE TO EVAPORATE BEFORE THEY CAN REACH THE SURFACE.
TRS
//PREV DISCUSSION...
234 PM CST
THE FORECAST CHALLENGES FOR TODAY ARE MAINLY TEMPERATURES AS
READINGS LOOK TO WARM LATER THIS EVENING THROUGH THE DAY SUNDAY
THEN A COOL DOWN INTO MONDAY...FOLLOWED BY A WARM-UP WITH WHAT
LOOKS TO POTENTIALLY BE 50S TO END NOVEMBER AND START
METEOROLOGICAL WINTER.
THE STUBBORN CYCLONIC FLOW AND ITS PESKY STRATUS IS ON THE WAY OUT
WITH A SURFACE RIDGE AXIS MOVING QUICKLY OVER THE AREA THIS EVE.
MID-LEVEL WARM AIR ADVECTION CLOUDS ARE ALREADY SPREADING OVER THIS
RIDGE ACROSS WESTERN IL AND SHOULD QUICKLY EXPAND EAST THROUGH THE
EVE. BEFORE THE ARRIVAL OF THESE CLOUDS IN THE HOURS AFTER
SUNSET...EASTERN AREAS SHOULD SEE TEMPERATURE DROPS THROUGH THE
20S GIVEN LIGHT WINDS. A GRADUAL CLIMB IN TEMPERATURES IS THEN
EXPECTED AREA WIDE AS PRESSURE FALLS AND RETURN FLOW SPREAD IN.
TEMPERATURES ARE LIKELY TO CLIMB BACK TO THE UPPER 20S TO MID 30S
BY DAYBREAK ON SUNDAY.
THE WARM AIR ADVECTION CLOUDS TONIGHT ARE ASSOCIATED WITH A STRONG
UPPER LEVEL LOW MOVING EAST ACROSS NORTHERN SASKATCHEWAN AND
MANITOBA...AND MORE SO WITH A RELATED PV ANOMALY AND SHORT WAVE
EXTENDING SOUTHWARD. THIS WILL TRANSLATE INTO WI BY OVERNIGHT AND
ALREADY TO THE EASTERN GREAT LAKES BY SUNDAY MORNING. SUPPORT FOR
UPWARD MOTION DOES SPREAD THIS FAR SOUTH AS REFLECTED IN RAP AND
NAM Q-VECTOR CONVERGENCE FIELDS. HOWEVER...SATURATION AND MID-
LEVEL MOISTURE CONVERGENCE IS BETTER SITUATED TO THE NORTH. THIS
DISJOINT WILL LIKELY KEEP PRECIPITATION TO THE NORTH...THOUGH
FLURRIES COULD GET CLOSE TO THE WI/IL STATE LINE LATER THIS EVE.
THE WARM SECTOR OF THIS CLIPPER-LIKE SYSTEM WILL CONTINUE OVER THE
AREA INTO SUNDAY. THIS HAS OFFERED 40S TO THE WEST OF THE REGION
IN NEBRASKA TODAY...AND ENVISION LOWER TO MID 40S DURING THE DAY
SUNDAY HERE. AS THE COLD FRONT MOVES THROUGH...WINDS WILL TURN
MORE NORTHWEST BY NIGHT AND TEMPERATURES WILL FALL BACK INTO THE
20S FOR LOWS.
TRENDS CONTINUE TO SUPPORT THIS LOW-LEVEL COOL AIR AND RIDGING
PUSH FROM THE NORTH TO EVOLVE THE PRIMARY BAROCLINIC ZONE TO THE
SOUTH OF THE AREA ON MON NIGHT AND TUE...AND THUS KEEP THE
PRIMARY FORCING FOR PRECIPITATION THERE AS WELL. AS THIS UNFOLDS
THOUGH...THERE STILL IS A WINDOW FOR SMALL CHANCES OF LIGHT SNOW
ACROSS THE SOUTHERN FORECAST AREA...MAINLY LATER MONDAY AFTERNOON
AND NIGHT. THE SPREAD IN THE SREF AND GEFS MEMBERS IS NOW LOW OVER
THE AREA...SO CONFIDENCE ON THIS IS FAIRLY HIGH.
BEYOND THIS...TEMPERATURES WILL SLOWLY MODERATE THROUGH MID WEEK
AS UPPER LEVEL RIDGING ACROSS THE WESTERN STATES EASES EAST.
WITH A LARGE CLOSED LOW OFF THE WEST COAST FORECAST CONSISTENTLY
BY GUIDANCE...THERE WILL BE LITTLE PROGRESSION OF MAJOR WEATHER
SYSTEMS. A QUICK MOVING UPPER LEVEL JET MAX AND ASSOCIATED SHORT
WAVE IS SEEN ON THU NIGHT/FRIDAY WITHIN THE SUITE OF LONG RANGE
GUIDANCE. AGAIN THERE CONTINUES TO BE DECENT BUT SHORT-LIVED
DYNAMICS FORECAST WITH THIS. HAVE INCREASED POPS SOME FROM A
PROVIDED GUIDANCE BLEND. TEMPERATURE SPREAD BY DAYS 6 AND 7 IN THE
FORECAST REALLY INCREASES IN GUIDANCE...SO CONFIDENCE
DROPS...HOWEVER GUIDANCE IS FAVORING TEMPERATURES TO BE ABOVE
NORMAL. ONE OF THE REASONS FOR SUCH SPREAD LOOKS TO BE CLOUD
COVER...AS THE DETERMINISTIC GFS DRAGS UP QUITE A BIT OF LOW-LEVEL
JUICE WITH THE THU NIGHT/FRI WAVE THAT MAY BE TOUGH TO SCOUR THIS
TIME OF YEAR.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* SW WINDS ARND 10 KT WILL SHIFT TO THE NW IN THE AFTN.
BEACHLER
//DISCUSSION...UPDATED 06Z...
HIGH PRESSURE HAS DRIFTED TO THE SOUTHEAST OF THE REGION ACROSS
THE TENN VALLEY. THIS HAS ALLOWED WINDS TO SHIFT SOUTHWEST ACROSS
NORTHERN IL/NORTHWEST IN. HOWEVER...A WEAK UPPER LEVEL SYSTEM THAT
IS CURRENTLY BRINGING MID/UPR LEVEL CLOUDS TO NORTHERN
IL/NORTHWEST IN AIRFIELDS...WILL PUSH A FRONTAL BOUNDARY ACROSS
THE REGION LATER TODAY. THIS WILL ALLOW WINDS TO SHIFT WEST THEN
NORTHWEST...WITH SPEEDS GENERALLY AROUND 10 KT. A FEW GUSTS MAY
OCCUR PERIODICIALLY THROUGHOUT THE AFTN IN THE 14 TO 18 KT RANGE.
OVERALL EXPECT VFR CONDS TO PREVAIL THROUGHOUT THE ENTIRE CURRENT
TAF TIMEFRAME.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* HIGH CONFIDENCE IN CIGS/VSBY FORECAST.
* HIGH CONFIDENCE IN WIND SPEED FORECAST.
* MEDIUM CONFIDENCE IN WIND DIR CHANGE.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...VFR.
TUESDAY...VFR.
WEDNESDAY...VFR.
THURSDAY...CHC RAIN/SNOW THURSDAY NIGHT.
FRIDAY...CHC RAIN.
BMD
&&
.MARINE...
257 AM CST
ACROSS THE NORTHERN GREAT LAKES...THE GRADIENT IS EXPECTED TO
TIGHTEN. THUS RESULTING IN INCREASED SOUTHWEST WINDS BETWEEN 15-25KT
TODAY. AS A BOUNDARY SLIDES SOUTH ACROSS THE LAKE...WINDS WILL
SLOWLY SHIFT TO NORTHWEST. IN ADDITION THE GRADIENT APPEARS TO
REMAIN TIGHT ACROSS MUCH OF THE LAKE...WHICH MOST LIKELY WILL RESULT
IN WINDS AROUND 30 KT TONIGHT THROUGH MUCH OF MONDAY. AT THIS TIME
IT APPEARS WINDS WILL REMAIN SUB-GALE CRITERIA...HOWEVER AN
OCCASIONAL GUST TO GALE FORCE MAY OCCUR.
ANOTHER RIDGE OF HIGH PRESSURE WILL SLIDE EAST FROM THE CENTRAL
PLAINS MONDAY NIGHT...ARRIVING ACROSS THE GREAT LAKES REGION
TUESDAY. THIS WILL ALLOW WINDS TO SHIFT YET AGAIN TO THE
WEST/SOUTHWEST. TUESDAY A WEAK LOW PRESSURE WILL TRAVERSE CENTRAL
ONTARIO...AND COULD RESULT IN WINDS NEAR THE STRAITS OF MACKINAW
SHIFTING TO NORTH/NORTHEAST FOR A PERIOD OF TIME. THEN ANOTHER
AREA OF LOW PRESSURE IS FORECAST TO SLIDE ACROSS ONTARIO
TUE/WED...WITH HIGH PRESSURE QUICKLY BUILDING IN BEHIND THIS
FEATURE FOR WED NGT/THUR.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...6 PM SUNDAY
TO 9 AM MONDAY.
SMALL CRAFT ADVISORY...LMZ744-LMZ745...6 PM SUNDAY TO 10 PM
MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1158 PM CST SAT NOV 24 2012
.DISCUSSION...
919 PM CST
NO SIGNIFICANT CHANGES IN THE FORECAST FOR THE REST OF TONIGHT
BESIDES MINOR TWEAKING OF GRIDDED DATA TO FIT WITH CURRENT
CONDITIONS.
WITH THE WARM AIR ADVECTION AND THICKENING CLOUDS AHEAD OF THE
SHORT WAVE TROUGH MOVING EAST-SOUTHEAST OVER NORTHWEST AND
SOUTHWEST MN AS WELL AS NORTHWEST IA THIS EVENING TEMPERATURES
HAVE HELD STEADY OR EVEN RECOVERED UP TO A COUPLE OF DEGREES F AS
THE SOUTH WINDS HAVE PICKED UP A BIT. NIGHTTIME MINIMUMS LIKELY
ALREADY REACHED SOME LOCATIONS WHILE OTHERS FALL OR RISE A DEGREE
OR TWO OVERNIGHT.
BY MID EVENING THE THICKENING MID LEVEL CLOUDS HAD SPREAD OVER ALL
BUT THE FAR SOUTH AND SOUTHEAST PARTS OF THE FORECAST AREA. RADAR
HAS BEEN DETECTING SOME RETURNS OF LATE AS LIFT RESULTING FROM
THE WARM AIR ADVECTION INCREASES. HOWEVER...LOW LEVELS ACROSS
SOUTHERN WI AS WELL AS NORTHERN IL AND NORTHWEST IN ARE DRY AND
ANY METEORS FALLING FROM THESE MID LEVEL CLOUDS HAVE BEEN AND
WILL CONTINUE TO EVAPORATE BEFORE THEY CAN REACH THE SURFACE.
TRS
//PREV DISCUSSION...
234 PM CST
THE FORECAST CHALLENGES FOR TODAY ARE MAINLY TEMPERATURES AS
READINGS LOOK TO WARM LATER THIS EVENING THROUGH THE DAY SUNDAY
THEN A COOL DOWN INTO MONDAY...FOLLOWED BY A WARM-UP WITH WHAT
LOOKS TO POTENTIALLY BE 50S TO END NOVEMBER AND START
METEOROLOGICAL WINTER.
THE STUBBORN CYCLONIC FLOW AND ITS PESKY STRATUS IS ON THE WAY OUT
WITH A SURFACE RIDGE AXIS MOVING QUICKLY OVER THE AREA THIS EVE.
MID-LEVEL WARM AIR ADVECTION CLOUDS ARE ALREADY SPREADING OVER THIS
RIDGE ACROSS WESTERN IL AND SHOULD QUICKLY EXPAND EAST THROUGH THE
EVE. BEFORE THE ARRIVAL OF THESE CLOUDS IN THE HOURS AFTER
SUNSET...EASTERN AREAS SHOULD SEE TEMPERATURE DROPS THROUGH THE
20S GIVEN LIGHT WINDS. A GRADUAL CLIMB IN TEMPERATURES IS THEN
EXPECTED AREA WIDE AS PRESSURE FALLS AND RETURN FLOW SPREAD IN.
TEMPERATURES ARE LIKELY TO CLIMB BACK TO THE UPPER 20S TO MID 30S
BY DAYBREAK ON SUNDAY.
THE WARM AIR ADVECTION CLOUDS TONIGHT ARE ASSOCIATED WITH A STRONG
UPPER LEVEL LOW MOVING EAST ACROSS NORTHERN SASKATCHEWAN AND
MANITOBA...AND MORE SO WITH A RELATED PV ANOMALY AND SHORT WAVE
EXTENDING SOUTHWARD. THIS WILL TRANSLATE INTO WI BY OVERNIGHT AND
ALREADY TO THE EASTERN GREAT LAKES BY SUNDAY MORNING. SUPPORT FOR
UPWARD MOTION DOES SPREAD THIS FAR SOUTH AS REFLECTED IN RAP AND
NAM Q-VECTOR CONVERGENCE FIELDS. HOWEVER...SATURATION AND MID-
LEVEL MOISTURE CONVERGENCE IS BETTER SITUATED TO THE NORTH. THIS
DISJOINT WILL LIKELY KEEP PRECIPITATION TO THE NORTH...THOUGH
FLURRIES COULD GET CLOSE TO THE WI/IL STATE LINE LATER THIS EVE.
THE WARM SECTOR OF THIS CLIPPER-LIKE SYSTEM WILL CONTINUE OVER THE
AREA INTO SUNDAY. THIS HAS OFFERED 40S TO THE WEST OF THE REGION
IN NEBRASKA TODAY...AND ENVISION LOWER TO MID 40S DURING THE DAY
SUNDAY HERE. AS THE COLD FRONT MOVES THROUGH...WINDS WILL TURN
MORE NORTHWEST BY NIGHT AND TEMPERATURES WILL FALL BACK INTO THE
20S FOR LOWS.
TRENDS CONTINUE TO SUPPORT THIS LOW-LEVEL COOL AIR AND RIDGING
PUSH FROM THE NORTH TO EVOLVE THE PRIMARY BAROCLINIC ZONE TO THE
SOUTH OF THE AREA ON MON NIGHT AND TUE...AND THUS KEEP THE
PRIMARY FORCING FOR PRECIPITATION THERE AS WELL. AS THIS UNFOLDS
THOUGH...THERE STILL IS A WINDOW FOR SMALL CHANCES OF LIGHT SNOW
ACROSS THE SOUTHERN FORECAST AREA...MAINLY LATER MONDAY AFTERNOON
AND NIGHT. THE SPREAD IN THE SREF AND GEFS MEMBERS IS NOW LOW OVER
THE AREA...SO CONFIDENCE ON THIS IS FAIRLY HIGH.
BEYOND THIS...TEMPERATURES WILL SLOWLY MODERATE THROUGH MID WEEK
AS UPPER LEVEL RIDGING ACROSS THE WESTERN STATES EASES EAST.
WITH A LARGE CLOSED LOW OFF THE WEST COAST FORECAST CONSISTENTLY
BY GUIDANCE...THERE WILL BE LITTLE PROGRESSION OF MAJOR WEATHER
SYSTEMS. A QUICK MOVING UPPER LEVEL JET MAX AND ASSOCIATED SHORT
WAVE IS SEEN ON THU NIGHT/FRIDAY WITHIN THE SUITE OF LONG RANGE
GUIDANCE. AGAIN THERE CONTINUES TO BE DECENT BUT SHORT-LIVED
DYNAMICS FORECAST WITH THIS. HAVE INCREASED POPS SOME FROM A
PROVIDED GUIDANCE BLEND. TEMPERATURE SPREAD BY DAYS 6 AND 7 IN THE
FORECAST REALLY INCREASES IN GUIDANCE...SO CONFIDENCE
DROPS...HOWEVER GUIDANCE IS FAVORING TEMPERATURES TO BE ABOVE
NORMAL. ONE OF THE REASONS FOR SUCH SPREAD LOOKS TO BE CLOUD
COVER...AS THE DETERMINISTIC GFS DRAGS UP QUITE A BIT OF LOW-LEVEL
JUICE WITH THE THU NIGHT/FRI WAVE THAT MAY BE TOUGH TO SCOUR THIS
TIME OF YEAR.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* SW WINDS ARND 10 KT WILL SHIFT TO THE NW IN THE AFTN.
BEACHLER
//DISCUSSION...UPDATED 06Z...
HIGH PRESSURE HAS DRIFTED TO THE SOUTHEAST OF THE REGION ACROSS
THE TENN VALLEY. THIS HAS ALLOWED WINDS TO SHIFT SOUTHWEST ACROSS
NORTHERN IL/NORTHWEST IN. HOWEVER...A WEAK UPPER LEVEL SYSTEM THAT
IS CURRENTLY BRINGING MID/UPR LEVEL CLOUDS TO NORTHERN
IL/NORTHWEST IN AIRFIELDS...WILL PUSH A FRONTAL BOUNDARY ACROSS
THE REGION LATER TODAY. THIS WILL ALLOW WINDS TO SHIFT WEST THEN
NORTHWEST...WITH SPEEDS GENERALLY AROUND 10 KT. A FEW GUSTS MAY
OCCUR PERIODICIALLY THROUGHOUT THE AFTN IN THE 14 TO 18 KT RANGE.
OVERALL EXPECT VFR CONDS TO PREVAIL THROUGHOUT THE ENTIRE CURRENT
TAF TIMEFRAME.
BEACHLER
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN CIGS/VSBY FORECAST.
* HIGH CONFIDENCE IN WIND SPEED FORECAST.
* MEDIUM CONFIDENCE IN WIND DIR CHANGE.
BEACHLER
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY...VFR.
TUESDAY...VFR.
WEDNESDAY...VFR.
THURSDAY...CHC RAIN/SNOW THURSDAY NIGHT.
FRIDAY...CHC RAIN.
BMD
&&
.MARINE...
217 PM...A RIDGE OF HIGH PRESSURE WILL PASS ACROSS LAKE MICHIGAN
EARLY THIS EVENING AS LOW PRESSURE OVER SOUTHERN MANITOBA MOVES
EAST ACROSS THE NORTHERN LAKES SUNDAY AND WEAKENS SUNDAY NIGHT.
THE GRADIENT WILL TIGHTEN TONIGHT BETWEEN THE APPROACHING LOW AND
THE WEAKENING RIDGE. WEST WINDS WILL SHIFT SOUTHWESTERLY THIS
EVENING AND STEADILY INCREASE TO 15-25KTS BY LATE EVENING AND
OVERNIGHT. SOME GUSTS TO 30 KTS ARE POSSIBLE ESPECIALLY OVER THE
SOUTHERN PART OF THE LAKE WHERE THE GRADIENT WILL BE TIGHTEST. A
TRAILING COLD FRONT FROM THIS LOW WILL MOVE ACROSS THE LAKE SUNDAY
AFTERNOON SHIFTING WINDS WESTERLY. AS ANOTHER AREA OF HIGH
PRESSURE MOVES SOUTHEAST FROM THE NORTHERN PLAINS SUNDAY NIGHT TO
THE SOUTHERN LAKES AND OHIO VALLEY MONDAY...THE GRADIENT WILL ONCE
AGAIN TIGHTEN WITH NORTHWEST WINDS 20-25KTS EXPECTED. GRADIENT
COULD BE STRONG ENOUGH FOR GUSTS TO 30KTS OVER NORTHERN LAKE
MICHIGAN. AS THIS HIGH SETTLES SOUTH OF THE LAKE ON TUESDAY...
WINDS WILL TURN SOUTHWESTERLY AND SHOULD RAPIDLY STRENGTHEN
TUESDAY AFTERNOON AS ANOTHER LOW MOVES ACROSS ONTARIO AND THE
NORTHERN LAKES WITH 30KTS AGAIN POSSIBLE OVER THE NORTHERN HALF OF
THE LAKE. ANOTHER AREA OF HIGH PRESSURE WILL MOVE ACROSS THE
MIDWEST AND LAKES REGION MID WEEK. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
315 AM CST SUN NOV 25 2012
.SHORT TERM /TODAY/...
SOMEWHAT COMPLICATED SHORT TERM TODAY AS MODELS NOT HANDLING THE
CLOUD COVER OVER MINNESOTA AT ALL. RAP MODEL HAS A BETTER IDEA THAT
STRATUS HAS FORMED AND HEADING SOUTH INTO THE REGION TODAY.
MEANWHILE THERE IS AN UPPER LEVEL BOUNDARY WITH UPSLOPE CLOUDS AND
LIGHT SNOW THAT IS ALSO CREATING A SHIELD OF CLOUDS SCHEDULED TO
HEAD EAST TOWARDS US LATER TODAY. THE COMBINATION OF SOME CLOUDS
EARLY AND MORE CLOUDS LATER WILL DAMPEN HIGHS TODAY. ALSO...THE
MAIN COLD FRONT NOW OVER NORTHWEST IOWA WILL SLIDE SOUTHEAST TODAY
KEEPING NORTHERN IOWA COOLER THAN THE REST OF THE REGION. HIGHS
THERE SHOULD TOP OUT IN THE MID 30S WHILE...WITH THE HEAD START IN
THE MID 30S...CENTRAL AND SOUTHERN IOWA WILL REACH THE LOWER TO MID
40S BY THE MID AFTERNOON. SOME AREAS MAY SEE AMPLE SUN EARLY TODAY
BUT WITH THICKENING CLOUDS MOST OF THE MORNING NORTH AND WEST/SOUTH
REGIONS LATER IN THE AFTERNOON IT SHOULD BE PARTLY SUNNY AT BEST IN
MANY LOCATIONS. WINDS WILL PICK UP BEHIND THE COLD FRONT AND
INCREASE TO ABOUT 10 TO 20 MPH WITH A FEW HIGHER GUSTS BY 2 TO 4 PM
AND THEN DIMINISH BY EVENING. NO PRECIPITATION IS EXPECTED.
.LONG TERM /TONIGHT THROUGH SATURDAY/...
A ZONAL THE NORTHWEST FLOW WILL REMAIN OVER THE CENTRAL CONUS FOR
THE BULK OF THE FORECAST PERIOD. THERE WILL ALSO BE VERY LITTLE
MOISTURE AROUND. THERE ARE SEVERAL SHORTWAVES IN THE UPPER FLOW AND
A COLD FRONT EXPECTED TO CONTINUE TO PASS EAST TONIGHT WITH LITTLE
FANFARE. COLDER AIR WILL SPILL INTO CENTRAL IOWA FOR MONDAY AND
MONDAY NIGHT. A DECENT SHORTWAVE IS PROGGED BY EVERY MEDIUM RANGE
MODEL TO PASS ACROSS THE STATE VERY LATE SUNDAY NIGHT THROUGH
MONDAY. WHAT IS ALSO INTERESTING IS THAT EVERY MODEL DEEPENS THE
WAVE JUST BEFORE IS SWINGS ACROSS IOWA...PUSHING THE FORCING AND THE
PRECIP A LITTLE FURTHER SOUTH. WITH A PRETTY DRY AIRMASS IN PLACE
AND THE FORCING ROM THE SHORTWAVE NOW SHIFTING SOUTH...I EXPECT
LITTLE MORE THAN FLURRIES ACROSS THE FAR SOUTHWEST AND SOUTH.
SHOULD THIS WAVE NOT DEEPEN AS MUCH OR IF THERE IS MORE MOISTURE
WITH THIS SYSTEM THAN THE MODELS ARE SUGGESTING THEN POPS WILL NEED
TO BE RAISED BUT FOR NOW...FLURRIES WILL COVER THE THREAT.
FOR MONDAY NIGHT THROUGH WEDNESDAY AN UPPER LEVEL RIDGE TRIES TO
ESTABLISH ITSELF OVER THE INTERMOUNTAIN WEST KEEPING A NORTHWEST
FLOW ACROSS THE UPPER MIDWEST. DRY AND SEASONAL TO SLIGHTLY BELOW
NORMAL TEMPERATURES ARE EXPECTED DURING THIS TIME.
MODELS DIVERGE SOME THURSDAY NIGHT INTO THE REMAINDER OF THE
EXTENDED. THE GFS DEVELOPS ANOTHER DECENT SHORTWAVE OVER THE REGION
AND THE GEM IS A LITTLE WEAKER AND FURTHER EAST WITH THIS FEATURE
WHILE THE EURO BARELY HAS A REFLECTION IN A MAINLY ZONAL FLOW. AT
THIS TIME I WILL KEEP THIS PERIOD DRY GIVEN THE GFS/S PROPENSITY FOR
OVERDOING PRECIP AND THE FACT THAT NONE OF THE OTHER MODELS PRODUCE
QPF. HOWEVER...I COULD SEE A CASE FOR PRECIP TO OUR EAST AS THE
WAVE DEEPENS JUST A BIT. FOR DAY 7...MODELS ALL HINT AT YET ANOTHER
SHORTWAVE PUSHING INTO THE UPPER MIDWEST BUT LOCATION AND TIMING ARE
NOT IN AGREEMENT. A SURFACE LOW IS BEING DEPICTED BY THE MODELS BUT
WITH UPPER RIDGING PRETTY MUCH IN PLACE I AM NOT LOOKING FOR A LOT
OF MOISTURE WITH THE SYSTEM SO ONCE AGAIN I WILL KEEP THE FORECAST
DRY UNTIL THERE IS BETTER AGREEMENT WITH MODELS AND I SEE SOME KIND
OF MOISTURE WORKING INTO THE REGION. THE MAIN THING FOR THE WEEKEND
IS THAT TEMPS WILL MODERATE TO READINGS ABOVE NORMAL WITH THE UPPER
RIDGING AND SOME LOWER LEVEL WAA WORKING INTO THE REGION.
&&
.AVIATION...25/06Z
BOUNDARY WILL PROGRESS THROUGH THE BOUNDARY OVERNIGHT WITH VFR
CEILINGS ACROSS MUCH OF THE STATE. HOWEVER...MVFR CIGS WILL LIKELY
CLIP THE NORTHEAST THIRD OF THE FORECAST AREA LATE TONIGHT INTO
SUNDAY MORNING AFFECTING BOTH KMCW AND KALO FOR A PERIOD OF TIME
DURING THE MORNING. BY AFTERNOON...ALL CEILINGS WILL RETURN TO VFR
WITH VISIBILITIES REMAINING UNRESTRICTED FOR THE DURATION OF THE
FORECAST. LIGHT WINDS FROM THE SOUTH WILL BE REPLACED WITH
NORTHWEST WINDS BEHIND THE BOUNDARY. THESE WINDS WILL BECOME GUSTY
ON SUNDAY AS PRESSURE GRADIENT TIGHTENS.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...REV
LONG TERM...FAB
AVIATION...COGIL
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1233 AM EST SUN NOV 25 2012
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 350 PM EST SAT NOV 24 2012
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW NW FLOW ALF OVER
THE GRT LKS BTWN TROF OVER ERN NAMERICA AND A RDG OVER THE ROCKIES.
RIGHT NOW...THERE IS A SHRTWV RDG ALF DOMINATING THE UPR LKS...WITH
SFC HI PRES RDG AXIS STRETCHING FM NOW ONTARIO S INTO THE UPPER
MIDWEST. DESPITE THE APRCH OF THIS RDG AXIS AND LO INVRN BASE SHOWN
ON THE 12Z INL/MPX RAOBS THAT HAS ALLOWED AT LEAST PARTIAL CLEARING
OF LO CLDS OVER MN...THE SC OVER THE CWA HAS BEEN QUITE RESILIENT
WITH H925-85 THERMAL TROF /H85 TEMPS IN THE -12C TO -15C RANGE/
UNDER HIER INVRNS H85-5 AS SHOWN ON THE 12Z GRB/APX RAOBS IN THE
LLVL NW FLOW E OF THE INCOMING SFC HI PRES RDG. THESE LO CLDS ARE
TENDING TO BREAK UP MORE AGGRESSIVELY OVER THE FAR SCENTRAL CWA WITH
DOWNSLOPE NATURE OF THE LLVL FLOW. ALTHOUGH LOWERING SUBSIDENCE
INVRN HAS TENDED TO CAUSE THE LES IN THE CHILLY NW FLOW TO DIMINISH
WITH TIME...THE SHSN HAVE BEEN MOST PERSISTENT NEAR MUNISING WITH
UPSTREAM MOISTENING OFF LK NIPIGON AND MORE LLVL CNVGC ENHANCING THE
LES IN THAT AREA. LOOKING TO THE W...SKIES ARE PCLDY CLOSE TO THE
SFC RDG AXIS...BUT THICKER CLDS ASSOCIATED WITH WAD IN THE SSW FLOW
AHEAD OF ANOTHER SHRTWV NEAR LK WINNIPEG THAT HAS BEEN RIDING OVER
THE ROCKIES RDG ARE MOVING STEADILY TO THE E INTO ERN MN THIS AFTN.
SOME -SN HAS MOVED INTO NW MN THIS AFTN UNDER DEEP ISENTROPIC
ASCENT/SOME UPR DVGC IN THE EXIT REGION OF 120KT H3 JET MAX
SUPPORTING THE SHRTWV.
MAIN FCST CONCERNS THRU SUN INCLUDE TIMING OF SN AND PCPN AMOUNTS
TNGT IN ADVANCE OF CLIPPER TYPE SHRTWV NEAR LK WINNIPEG AND THEN
TRANSITION TO LES ON SUN IN ITS WAKE.
TNGT...AS SFC HI PRES RDG SHIFTS TO THE ERN GRT LKS...EXPECT SW
FLOW/ISENTROPIC ASCENT BTWN DEPARTING RDG AND SHRTWV NEAR LK
WINNIPEG TRACKING TO THE ESE ACRS ONTARIO TO DOMINATE. SINCE THE
MAIN PV ANOMALY WL BE PASSING TO THE N...SHARPER ISENTROPIC ASCENT
BEST SHOWN ON THE 280-290K SFCS /H8-65/ WL BE TRANSIENT AS WARM
CONVEYOR BELT MSTR AXIS SWINGS THRU THE UPR LKS AHEAD OF DRY
SLOTTING ON THE SRN FLANK OF PV ANOMALY TRACK. -SN SHOULD ARRIVE
OVER THE W IN THE EVNG AND PUSH TO ERY AFTER 06Z...WHEN THE PCPN WL
BEGIN TO DIMINISH W-E FOLLOWING THE SHIFT OF THE WARM CONVEYOR BELT
RIBBON TO THE E. PCPN CHCS WL BE ENHANCED BY RIBBON OF H85-7 FGEN...
SOME UPR DVGC IN LEFT EXIT REGION OF H3 JET MAX SUPPORTING THE
ONTARIO SHRTWV...AND SOME DPVA ASSOCIATED WITH ANOTHER SHRTWV
TRACKING THRU THE UPR MIDWEST ON THE SRN FLANK OF THE MAIN PV
ANOMALY. GIVEN FCST H7 SPECIFIC HUMIDITY UP TO 2 G/KG AND A 3-6 HR
PERIOD OF -SN WITH TRANSIENT WARM CONVEYOR BELT/DEEP ASCENT...LOOKS
LIKE 1 TO 2 INCHES OF SN IS LIKELY WITH DECENT OMEGA IN THE DGZ. 12Z
GUIDANCE SHOWS THE SHARPER ISENTROPIC ASCENT/FGEN IMPACTING THE WI
BORDER AREA WITH HIER QPF/SN AMOUNTS ARND 2 INCHES MOST LIKELY
THERE. SOME OF THE MODELS ALSO HINT THERE COULD BE SOME LK
ENHANCEMENT OFF LK MI...BUT THE H925 WINDS LOOK TO BACK TO A MORE
FAVORABLE SW DIRECTION ONLY BRIEFLY TO ALLOW FOR TOO MUCH
ENHANCEMENT AT ISQ-ERY. WITH RELATIVELY QUICK ARRIVAL OF THICKER
CLDS/WAD THIS EVNG...EXPECT NEAR STEADY TEMPS MUCH OF THE NGT AFTER
EARLY MODEST DIURNAL TEMP FALL.
SUN...LINGERING -SN OVER THE E WL END SOON AFTER 12Z FOLLOWING EXIT
OF WARM CONVEYOR BELT MSTR RIBBON TO THE E AND ARRIVAL OF DRY
SLOTTING. HOWEVER...12Z MODELS HAVE TENDED TO DIG THE PV ANOMALY
MORE TO THE ESE OVER NE LK SUP DURING THE DAY. SO AS THE DAY GOES
ON...A COLD CYC NW FLOW WL DVLP IN THE WAKE OF COLD FROPA AS
ASSOCIATED SFC LO SHIFTS TO JUST E OF LK SUP BY 00Z MON. AT THE SAME
TIME...AN AXIS OF SHARPER QVECTOR CNVGC/DPVA AND SOME DEEPER MSTR WL
IMPACT MAINLY THE NE HALF OF THE FA CLOSER TO THE TRACK OF THE
SHRTWV. WITH H85 TEMPS PROGGED TO FALL AS LO AS -15C OVER THE W HALF
OF LK SUP IN THE AFTN...EXPECT MORE WDSPRD LES TO DEVELOP IN THAT
AREA. ALSO BUMPED UP POPS OVER THE NE IN THE AFTN ESPECIALLY NEAR LK
SUP GIVEN FAVORABLE ALIGNMENT OF ONSHORE WNW FLOW...DEEPER MSTR/
DPVA/QVECTOR CNVGC...AND COOLING. THE DAY SHOULD BE DRY OVER THE
SCENTRAL WITH DOWNSLOPE FLOW IN THE ABSENCE OF ANY DYNAMIC
SUPPORT/DEEP MSTR THERE.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 350 PM EST SAT NOV 24 2012
THE MAIN FOCUS IN THE LONG TERM REVOLVES AROUND THE CHANCE FOR
MODERATE LAKE EFFECT SNOW ACCUMULATION EAST NEAR LAKE SUPERIOR
LATE SUNDAY NIGHT THROUGH MONDAY. EXACT LOCATIONS OF THIS POTENTIAL
ARE STILL UNCERTAIN...THOUGH THE MAIN THREAT APPEARS TO BE IN ALGER
COUNTY FROM MUNISING TO GRAND MARAIS AND SOUTH INTO NORTHERN
SCHOOLCRAFT COUNTY. ANOTHER ROUND OF LIGHT SNOW VERY SIMILAR TO
TONIGHTS SYSTEM WILL MOVE THROUGH THE AREA TUESDAY NIGHT. MILDER
PATTERN CHANGES WILL THEN BE IN THE MAKING TOWARD THE END OF THE
WEEK.
SUNDAY NIGHT THROUGH MONDAY NIGHT...THE SHORTWAVE TROUGH ASSOCIATED
WITH THE CLIPPER SYSTEM NOTED IN THE SHORT TERM WILL BE CROSSING
NORTH-CENTRAL LAKE SUPERIOR AND WESTERN UPPER MI AT THE START OF THE
PERIOD. THE ECMWF AND REGIONAL GEM HAVE BEEN QUICKER WITH THE
SHORTWAVE WITH EACH PROGRESSIVE RUN...AND HAVE COME IN LINE WITH THE
GFS AND NAM SOLUTIONS. TRENDS FROM BOTH THE GFS AND ECMWF ARE TO ADD
SUBTLE AMPLIFICATION TO THE WNW FLOW IN THE MID-LEVELS OVER THE
GREAT LAKES...WHILE THE REGIONAL GEM HAS TRENDED TO A LESS AMPLIFIED
FLOW. PREFER THE IDEA PRESENTED BY THE GFS/ECMWF AS THE NICE SHOT OF
CAA BEHIND THE LOW-LEVEL CLIPPER WILL LIKELY ADD SOME AMPLIFICATION
TO THE MID-LEVEL TROUGHING.
LINGERING LIGHT SNOW FROM THE CLIPPER WILL BE ENDING ACROSS THE
EASTERN PORTION OF THE CWA AT 00Z MONDAY AS THE LOW DEPARTS INTO SE
ONTARIO. CAA IMMEDIATELY BEHIND THE SYSTEM IS NOT ALL THAT
IMPRESSIVE...WITH H8 TEMPS ONLY AROUND -10C OVER EASTERN LAKE
SUPERIOR AT 06Z MONDAY. HOWEVER...H8 TEMPS BEGIN TO FALL FOR THE
WESTERN HALF...REACHING -14C BY 06Z MONDAY. AT THE SAME TIME...A
WEAK RIDGE BETWEEN THE DEPARTING TROUGH AND INCOMING AMPLIFYING
TROUGH WILL BE PASSING OVERHEAD AND LIKELY DISRUPT THE LOW-LEVEL
SURFACE FLOW. WHAT MAKES THIS CONCERNING IS THAT SFC TO H8 FLOW FROM
THE NW WOULD PUT A DOMINANT LES BAND INTO FAR EASTERN ALGER COUNTY
BEGINNING SUNDAY EVENING...WHILE A BACKING OF THE FLOW BEHIND THE
SUBTLE RIDGE WOULD TEMPORARILY PUSH THE BAND ALONG THE SHORE. STILL
BEING TWO DAYS OUT...THE CONNECTION BETWEEN THE MID-LEVEL FLOW AND
SFC LES SET-UP IS SOMEWHAT UNCLEAR...BUT WOULD NOT BE SURPRISED IF
THE BAND WOBBLES BETWEEN EASTERN ALGER COUNTY AND NORTHERN LUCE
COUNTY ON EARLY MONDAY MORNING. THEN...THE SECONDARY TROUGH WILL AID
LES INTENSITY ACROSS THE WHOLE NORTH SHORE OF UPPER MI LATER MONDAY
MORNING INTO THE AFTERNOON. THIS WILL OCCUR AS THE BEST CAA AND
COLDEST H8 TEMPS...AROUND -15 TO -16C...WILL BE MOVING OVER THE
LAKE. ADDITIONALLY...LAKE-INDUCED EQUILIBRIUM VALUES BASED OFF OF A
CONSERVATIVE LAKE WATER TEMPERATURE OF 5C WILL BE UPWARDS OF 7KFT
ACROSS THE WEST AND 9KFT FOR THE EAST. FINALLY...THE DGZ WILL BE
LOCATED IN THE HIGHEST 3KFT OF THE CONVECTIVE LAYER IN THE
EAST...LEADING TO THE POTENTIAL FOR INCREASED AGGREGATION FROM
DENDRITES AND THUS HIGHER SNOW RATIOS OF ABOUT 20 TO 1.
THEREFORE...EXPECT THE HIGHEST LES INTENSITY MONDAY MORNING INTO
EARLY AFTERNOON OVER THE EAST NEAR LAKE SUPERIOR.
THE NAM...GEM...AND LOCAL WRF ALL HAVE A DOMINANT BAND WITH
SIGNIFICANT LES FOR CENTRAL ALGER AND NORTHERN SCHOOLCRAFT COUNTY. A
BLEND OF NAM AND LOCAL WRF QPF RESULTED IN ACCUMULATIONS OF 6-10
INCHES CENTERED OVER MELSTRAND. ONLY USED THIS BLEND TO SEE
POTENTIAL AND WILL USE A MORE CONSERVATIVE APPROACH GIVEN THE
UNCERTAINTY OF BAND PLACEMENT. NEEDLESS TO SAY...HEADLINES MAY BE
NEEDED IF HI-RES MODELS REMAIN CONSISTENT WITH LES BAND PLACEMENT.
DRY AIR ADVECTION FROM THE SOUTHWEST IN THE LOW LEVELS...AND H8 WAA
OVERNIGHT MONDAY WILL BEGIN TO ERODE LES FROM WEST TO EAST ACROSS
THE CWA. INVERSION HEIGHTS WILL ALSO CRASH FROM AROUND 9KFT 00Z
TUESDAY TO <5KFT BY 09Z TUESDAY. MEANWHILE WINDS WILL BEGIN BACKING
AND SHOULD PUSH REMAINING LES OFFSHORE...WITH LITTLE ACTIVITY
REMAINING BY TUESDAY MORNING.
TUESDAY THROUGH WEDNESDAY...ANOTHER SHORTWAVE TROUGH DIGGING ESE OUT
OF CANADA WILL IMPACT THE CWA BY TUESDAY AFTERNOON AND BRING A ROUND
OF LIGHT SNOW TO MAINLY THE NORTHERN CWA. THE BEST UPPER LEVEL PV
ANOMALY AND MID-LEVEL Q-VECTOR DIVERGENCE ARE PROGGED TO MOVE
THROUGH TUESDAY AFTERNOON AND EVENING. THE LEFT EXIT OF A 120KT NW
TO SE ORIENTED UPPER JET WILL BE TRACKING ACROSS CENTRAL WI...SO
BEST FEATURES DO NOT QUITE LINE UP. THE LOWEST LEVELS WILL BE DRY
ENOUGH TO THE SOUTH TO PREVENT INITIAL PRECIP FROM REACHING THE
GROUND. DID NOT MAKE MANY CHANGES TO THE PREVIOUS FORECAST OTHER
THAN INCREASE POPS SLIGHTLY FOR THE ENTIRE CWA. THE TROUGH AXIS WILL
THEN PASS THROUGH THE CWA BY 12Z WEDNESDAY AND USHER IN
ANOTHER...YET SHORT-LIVED AND WEAKER...LES EVENT. INVERSION HEIGHTS
COLLAPSE QUITE QUICKLY TO ABOUT 4KFT BY WEDNESDAY AFTERNOON...AND
THE AIR BEHIND THIS SYSTEM IS CONSIDERABLY DRY THROUGHOUT THE
COLUMN. THEREFORE...EXPECTATION IS THAT THERE WILL BE A QUICK LES
EVENT WEDNESDAY MORNING INTO EARLY AFTERNOON FOR THE NW
SNOWBELTS...MAINLY ACROSS THE KEWEENAW PENINSULA AND EAST OF
MUNISING WHERE MOISTURE IS MORE ABUNDANT.
WEDNESDAY NIGHT THROUGH SATURDAY...THE PATTERN TURNS QUIET FOR MUCH
OF THE UPPER GREAT LAKES FOR THE SECOND HALF OF THE WEEK. OTHER THAN
SOME LIGHT LES POSSIBLE EAST NEAR LAKE SUPERIOR ON THURSDAY
NIGHT...NO REAL SIGNIFICANT PRECIP CHANCES PRESENT THEMSELVES AS THE
MAIN ENERGY REMAINS SOUTH OF THE CWA WITH AN UPPER LEVEL DISTURBANCE
MOVING ACROSS THE MID MISSISSIPPI VALLEY ON FRIDAY. THOUGH ON THE
EDGE OF THE FORECAST PERIOD...A STRONG RIDGE WITHIN PACIFIC FLOW
LOOKS TO BRING WELL-ABOVE AVERAGE TEMPS TO BEGIN DECEMBER.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1232 AM EST SUN NOV 25 2012
CLIPPER TYPE LOW PRES SYSTEM IS CURRENTLY BRINGING -SN TO
KIWD/KCMX/KSAW WITH IFR VIS GENERALLY PREVAILING. ALTHOUGH -SN WILL
END FROM W TO E OVER THE NEXT SEVERAL HRS...EXPECT LINGERING MVFR
CIGS WITH RESIDUAL LOW-LEVEL MOISTURE. ARRIVAL OF COLDER AIR WILL
GENERATE MORE LAKE EFFECT -SHSN THIS MORNING AT KIWD AND ESPECIALLY
AT KCMX WHERE THE EXPECTED W WIND WILL UPSLOPE. ON THE OTHER HAND...
CONDITIONS ARE LIKELY TO TREND TO VFR AT KSAW WITH DOWNSLOPE WIND
COMPONENT. AS INCREASINGLY COLDER AIR MOVES INTO THE UPPER LAKES...
LAKE EFFECT -SHSN SHOULD BECOME HEAVIER AT KIWD/KCMX LATE AFTN INTO
THE EVENING WITH IFR VIS BECOMING MORE LIKELY.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 350 PM EST SAT NOV 24 2012
EXPECT S-SW WINDS UP TO 20 KTS IN ADVANCE OF A CLIPPER SYSTEM
TONIGHT TO VEER TO THE WNW ON SUN AS THE LO MOVES TO THE E OF LAKE
SUP AND DRAGS A COLD FRONT ACROSS THE AREA.
NORTHWEST WINDS OF 20 TO 30 KNOTS DUE TO HIGH PRESSURE QUICKLY
IMPINGING ON A DEPARTING LOW OVER FAR EASTERN UPPER MICHIGAN WILL BE
POSSIBLE SUNDAY NIGHT...WITH EVEN A FEW GALE FORCE GUSTS UP TO 35
KNOTS NOT OUT OF THE QUESTION. EXPECT THESE WINDS TO QUICKLY
DECREASE ON MONDAY AS A HIGH PRESSURE RIDGE SETTLES OVER THE UPPER
GREAT LAKES. SOUTHWEST WINDS OF 20 TO 25 KNOTS WILL THEN BE
POSSIBLE...MAINLY FOR THE WEST HALF OF LAKE SUPERIOR ON TUESDAY
AHEAD OF A COLD FRONT. ONCE THE FRONT PASSES TUESDAY AFTERNOON AND
EVENING...WINDS WILL VEER TO THE W/NW AND INCREASE TO 20 TO 25 KNOTS
FOR THE EAST HALF OF THE LAKE THROUGH WEDNESDAY. EXPECT WINDS TO
REMAIN BELOW 20 KNOTS FOR THE REMAINDER OF THE PERIOD.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KLUBER
AVIATION...ROLFSON
MARINE...KC/KLUBER
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
331 AM CST SUN NOV 25 2012
.DISCUSSION...
THE MAIN FORECAST CONCERN CONTINUES TO CENTER THE THE SHORTWAVE
CURRENTLY LOCATED OVER THE STATE OF WA EARLY THIS MORNING PER IR
SAT IMAGERY. THIS SHORTWAVE TROUGH AND ASSOCIATED FORCING FOR
ASCENT WILL TRACK EAST TODAY...AND ACROSS THE REGION LATE TONIGHT
AND INTO MONDAY MORNING. AHEAD OF THE WAVE...ALONG THE PRE-
EXISTING MID LEVEL THERMAL GRADIENT...WEAK CONFLUENT FLOW WILL
CONTINUE TODAY LEADING TO A GOOD DEAL OF MID AND HIGH LEVEL CLOUDS
FOR THE CNTRL AND NORTHERN FORECAST AREA. THE RAP APPEARS TO HAVE
THE BEST HANDLE ON THE STRATUS DECK OVER THE EASTERN DAKOTAS/MN
THIS MORNING AND THE MODEL INDICATES THE CLOUDS WILL MOVE INTO
NORTHEAST NEB AND WEST CNTRL IA...WHICH SEEMS REASONABLE BUT THIS
IS LIKELY THE FARTHEST SOUTH THE LOW CLOUDS WILL GET TODAY. THE
DEGREE OF LOW LEVEL DRY AIR OVER THE NRN CWA NEAR THE THERMAL
GRADIENT CONTS TO MAKE THE CHANCE OF ANY PRECIP MAKING IT TO THE
SURFACE UNLIKELY TODAY AND WE WILL MAINTAIN THE DRY FORECAST.
A LITTLE BETTER FRONTAL CIRCULATION WILL START TO DEVELOP TONIGHT
AS THE QG FORCING ASSOCIATED WITH THE INCOMING SHORTWAVE STARTS
SPREADING INTO THE AREA. THE ATMOSPHERE ABOVE THE FRONTAL ZONE IS
VERY STABLE THOUGH WITH EPV VALUES ABOVE 1 PVU AND THUS OVERALL
VERTICAL MOTION DUE TO THE 700-750 MB FRONTOGENESIS APPEARS LIKE
IT WILL BE FAIRLY WEAK. NEVERTHELESS WITH THE LONG DURATION OF
PERSISTENT WEAK LIFT THE ATMOSPHERE WILL TRY TO SATURATION FROM
THE TOP DOWN WITH SOME LIGHT SNOW REACHING THE SURFACE IN A FAIRLY
NARROW BAND FROM AROUND BVN/OLU/LNK BY MON MORNING. WE HAVE
CONTINUED TO MENTION SOME HALF INCH SNOW TOTALS IN THIS SMALL
AREA WHERE WE HAVE ALSO INCREASED POPS. WE HAVE LOWERED OR REMOVED
POPS MOST OTHER PLACES WITH JUST SOME FLURRIES POSSIBLE LATE
TONIGHT INTO MON. THE LIGHT SNOW WILL LIKELY LINGER INTO MONDAY
MORNING IN THE PREVIOUSLY MENTIONED BAND BEFORE THE UPPER LEVEL
SHORTWAVE TROUGH QUICKLY EXITS TO THE EAST AND LARGE-SCALE
SUBSIDENCE DEVELOPS BY MON AFTERNOON. THIS SHOULD ACT TO START TO
CLEAR THE CLOUDS BY LATE AFTERNOON FOR A GOOD PART OF THE AREA AS
WEAK SURFACE HIGH PRESSURE BUILDS IN.
NORTHWEST FLOW WILL CONTINUE FOR THE REST OF THE FORECAST PERIOD
BECOMING INCREASINGLY WESTERLY BY LATE IN THE PERIOD. THIS IS A
FAIRLY UNSTABLE UPPER LEVEL PATTERN AND SO CONFIDENCE IN THE
SENSIBLE WEATHER LATE IN THE PERIOD IS PRETTY LOW. THE GFS HAS A
STRONGER SYSTEM MOVING THROUGH THE AREA ON THU BUT THE MODEL
APPEARS TO BE AN OUTLIER WHEN COMPARED TO OTHER GLOBAL GUIDANCE
AND WE WILL DISREGARD FOR NOW. TEMPERATURES WILL SLOWLY WARM
THROUGH THE PERIOD WITH HIGHS/LOWS WELL ABOVE NORMAL BY NEXT
WEEKEND.
BOUSTEAD
&&
.AVIATION...
06Z TAFS FOR KOFK...KOMA AND KLNK.
WEAK WIND SHIFT WAS PRESSING TOWARD LNK AND OMA LATE SATURDAY
EVENING. A SOMEWHAT STRONGER BOUNDARY OVER NRN SD WILL MOVE INTO
NRN NEBRASKA LATE TONIGHT BEFORE WEAKENING DURING THE DAY AS IT
CONTINUES SOUTHWARD. LOW CLOUDS BEHIND THIS FRONT WILL NEED
MONITORING AS IT APPEARS THEY COULD APPROACH KOFK AND POSSIBLY
EVEN OMAHA BEFORE ERODING OR REORGANIZING TO THE WEST. OTHERWISE A
DISTURBANCE MOVING SE TOWARD CENTRAL NEBRASKA SHOULD BRING LOWER
CIGS TO OMA/OFK SUNDAY EVENING AND SNOW CHANCES TO THE AREA SUN
NIGHT/MONDAY MORNING. WITH LOW LEVEL DRY AIR EXPECTED TO BE IN
PLACE SUN AFTN...NO SNOW MENTION OR MVFR CIGS WERE FORECAST BEFORE
25/06Z.
CHERMOK
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
305 AM CST SUN NOV 25 2012
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
305 AM CST SUN NOV 25 2012
MAIN FORECAST CONCERNS ARE ON CLOUDS THROUGH THE PERIOD AND
TEMPERATURES.
07Z SURFACE ANALYSIS SHOWS TROUGH RUNNING FROM SOUTH CENTRAL
MINNESOTA...INTO NORTHWEST WISCONSIN. LARGE SHIELD OF STRATO-CUMULUS
SEEN BEHIND IT EXTENDING ALL THE WAY INTO THE DAKOTAS...MOVING
SOUTHEAST TOWARDS THE AREA. SNOW ACROSS CLARK AND TAYLOR COUNTIES
WAS EXITING EASTWARD.
25.00Z MODELS STRUGGLING WITH HANDING OF THE NEAR TERM
STRATO-CUMULUS DECK...WITH THE RAP DOING THE BEST.
OTHERWISE...MODELS IN GOOD AGREEMENT THROUGH THE REMAINDER OF THE
PERIOD.
IN THE NEAR TERM...25.03Z RAP RELATIVE HUMIDITY PROGS SHOW STRATUS
FIELD OVER MINNESOTA TO PUSH ACROSS THE FORECAST AREA TODAY IN THE
WAKE OF THE SURFACE TROUGH. 25.12Z NAM ON THE OTHER HAND SHOWS THIS
STRATUS OVER MAINLY THE NORTHERN SECTIONS. RAP VERIFYING BEST AT 07Z
AND THUS GOING FOR THE MORE PESSIMISTIC CLOUD FORECAST TODAY...WITH
MOSTLY CLOUDY SKIES. WITH THE CLOUDS AND 925MB-700MB COLD
ADVECTION...TEMPERATURES WILL NOT REBOUND MUCH FROM MORNING LOWS AND
THUS DID COOL TEMPERATURES A FEW DEGREES FROM THE PREVIOUS FORECAST
AND THIS INLINE WITH GUIDANCE TRENDS OF BEING COOLER.
HIGH PRESSURE BEGINS TO BUILD INTO THE NORTHERN PLAINS/MINNESOTA
TONIGHT. AS DRIER AIR ADVECTS INTO THE REGION DO EXPECT THE CLOUDS TO
BREAK UP SOMEWHAT...WITH SOME CLEARING LIKELY AS THE NIGHT WEARS
ON. SOME CONCERN THAT LOW LEVEL MOISTURE WILL GET TRAPPED UNDER
THE INVERSION AND THUS SEE VERY LITTLE CLEARING. ALSO CANNOT RULE
OUT A FEW FLURRIES THIS EVENING...BUT DID NOT INCLUDE IN THE GRIDS
AT THIS TIME. EXPECT TEMPERATURES TO DROP INTO THE TEENS...AND
PERHAPS A LITTLE COLDER IN AREAS WHERE SKIES WOULD CLEAR.
THE HIGH THEN SETTLES OVERHEAD MONDAY AND MONDAY NIGHT. WITH
850MB TEMPERATURES RANGING FROM -5 DEGREES ACROSS THE FAR SOUTH TO
-12 DEGREES IN THE NORTH...EXPECT THIS TO BE THE COLDEST DAY OF
THE WEEK...WITH HIGHS ONLY IN THE 20S.
THE HIGH WILL TRANSLATE TO THE SOUTHEAST ON TUESDAY...WITH WARM
ADVECTION ON ITS BACK SIDE AS WINDS COME AROUND TO THE SOUTHWEST.
WITH THE 850MB-700MB WARM ADVECTION...A BAND OF MID LEVEL CLOUDS ARE
EXPECTED TO TRAVERSE THE AREA. WITH 850MB TEMPERATURES IN THE -5 TO
-8 DEGREES CELSIUS RANGE...EXPECT HIGHS IN THE UPPER 20S TO MIDDLE
30S. A SHORTWAVE WILL TRANSLATE ACROSS LAKE SUPERIOR LATE IN THE
DAY...DRAGGING A WEAK SURFACE TROUGH THROUGH THE AREA. THIS WILL BE
NO MORE THAN A WIND SHIFT...WITH ANT PRECIPITATION REMAINING WELL TO
THE NORTH OF THE AREA NEAR THE MAIN WAVE. THE SOUTHWESTERLY WINDS
WILL KEEP TEMPERATURES FROM BOTTOMING OUT TUESDAY NIGHT...WITH LOWS
IN THE TEENS AND 20S.
.LONG TERM...WEDNESDAY THROUGH SATURDAY
305 AM CST SUN NOV 25 2012
NORTHWESTERLY FLOW WITH HIGH PRESSURE AT THE SURFACE ON WEDNESDAY
WILL GIVE WAY TO A MORE ZONAL FLOW FROM THURSDAY THROUGH SATURDAY.
25.00Z GFS AND ECMWF DO DIFFER IN THEIR SOLUTIONS IN HANDLING THE
VARIOUS SHORTWAVES MOVING THROUGH THE FLOW. GFS DEPICTS A SHORTWAVE
IN THE FLOW OVER THE CENTRAL PLAINS ON THURSDAY...WHILE THE ECMWF IS
MUCH WEAKER AND FURTHER SOUTH OVER TEXAS. IN EITHER CASE...SOME
TRANSPORT OF LOW LEVEL MOISTURE MAY WORK ITS WAY NORTHWARD INTO
EASTERN IOWA AND SOUTHERN WISCONSIN THURSDAY NIGHT AND BRING A
SLIGHT CHANCE FOR SOME LIGHT PRECIPITATION TO THE AREA.
OTHERWISE...REMAINDER OF THE FORECAST PERIOD LOOKS DRY...WITH A
GRADUAL WARMING TREND INTO THE WEEKEND. IN FACT BOTH THE ECMWF AND
GFS ARE SHOWING 850MB TEMPERATURES RISING TO 8 TO 10 DEGREES
CELSIUS SATURDAY. THUS EXPECT TEMPERATURES TO WARM INTO THE MIDDLE
TO UPPER 40S AND PERHAPS 50 IN A FEW LOCATIONS.
&&
.AVIATION...THROUGH 06Z MONDAY
1108 PM CST SAT NOV 24 2012
THE SURFACE COLD FRONT HAS PUSHED ABOUT HALF AWAY ACROSS MINNESOTA
THIS EVENING. MID LEVEL CLOUDS ASSOCIATED WITH THE SHORT WAVE
TROUGH WILL BE EXITING THE REGION EARLY IN THE PERIOD ONLY TO BE
REPLACED BY LOWER CLOUDS. UPSTREAM OBSERVATIONS INITIALLY INDICATE
THE CEILINGS SHOULD LOWER TO AROUND 5K FEET AHEAD OF THE
FRONT...BUT THEN ONCE THE FRONT MOVES THROUGH...THESE SHOULD LOWER
TO MVFR. IR FOG PRODUCT SHOWS THIS MVFR DECK IS RATHER EXPANSIVE
COVERING MUCH OF NORTH DAKOTA BUT THE BACK EDGE SEEMS TO BE MOVING
ACROSS SOUTHERN SASKATCHEWAN. THE 25.03Z RAP HAS LOCKED ON TO
THIS MOISTURE AND BRINGS IT INTO THE AREA AND THEN TRAPS IT UNDER
THE LOW LEVEL INVERSION SUGGESTING THE CLOUDS WOULD LINGER THROUGH
MUCH OF SUNDAY. WILL INDICATE THESE CLOUDS COMING INTO BOTH TAF
SITES WITH THE FRONTAL PASSAGE BUT WITH A BACK EDGE VISIBLE ON
THE SATELLITE...WILL SHOW THEM SCATTERING OUT AROUND 18Z BASED ON
THE TIMING OF THE CURRENT MOVEMENT. IF THE CLOUDS DO NOT SCATTERED
OUT SUNDAY MORNING...WOULD THEN EXPECT THEM TO PERSIST INTO SUNDAY
NIGHT AS THE 25.00Z NAM DOES DISSIPATE THE LOW LEVEL INVERSION.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
305 AM CST SUN NOV 25 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RABERDING
LONG TERM...RABERDING
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1108 PM CST SAT NOV 24 2012
.SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
300 PM CST SAT NOV 24 2012
MAIN FORECAST CONCERNS THIS PACKAGE...LIGHT SNOW CHANCES ACROSS THE
NORTH TONIGHT...CLOUD/TEMPERATURE TRENDS THRU THE PERIOD.
DATA ANALYSIS AT 18Z HAD A RIDGE OF HIGH PRESSURE FROM WESTERN ONT
THRU WI TO AR AND LOW PRESSURE FROM EASTERN CO TO LK WINNIPEG.
STRATO-CU CLOUDS CLEARING OVER WI/IL AS THE RIDGE AXIS MOVES EAST.
WINDS QUICKLY TURN SOUTH/SOUTHEAST ACROSS MN/IA WEST OF THE RIDGE
AXIS. 850-700MB WARM ADVECTION/ISENTROPIC LIFT AHEAD OF THE NEXT
TROUGH INTO THE NORTHERN PLAINS WAS ALREADY SPREADING MID LEVEL
MOISTURE/CLOUDS EASTWARD ACROSS MN/IA BEHIND THE RIDGE AXIS. EVEN
WITH SOME SUNSHINE AND SNOW-FREE GROUND ACROSS MOST OF THE FCST AREA
THIS MORNING...TEMPERATURES SLOW TO WARM WITH MID-DAY READINGS ONLY
IN THE MID 20S.
24.12Z MODELS INITIALIZED WELL AND OFFER VERY SIMILAR SOLUTIONS FOR
TONIGHT INTO TUE NIGHT AS WEAK SHORTWAVES IN NORTHWEST FLOW PASS
NEAR OR ACROSS THE UPPER MIDWEST. DPROG/DT OF 500MB HGTS AT 24.12Z
SHOWED THE MODEL RUNS OF 22.12Z AND 23.12Z VERIFIED QUITE WELL
ACROSS NOAM/EASTERN PAC. STRONGER OF EARLIER RUNS BETTER WITH
SHORTWAVE FEATURES OVER SASKAT AND SOUTHERN BC. LATEST RUNS
CONVERGED TOWARD A TIGHT CONSENSUS TONIGHT/SUN...FAVORING FASTER OF
EARLIER RUNS WITH FEATURES MOVING EAST NEAR THE US/CAN BORDER. TREND
IS TOWARD A COMPROMISE ON STRENGTH/TIMING OF THE NEXT SHORTWAVE
TROUGH INTO THE MID/UPPER MS VALLEY MON THEN INTO THE EASTERN U.S.
TUE. ECMWF WITH THE SOMEWHAT BETTER RUN-TO-RUN CONSISTENCY THIS
CYCLE. CHECK OF OBS VS. MODEL DATA AT 18Z SHOWED MODELS GENERALLY
GOOD WITH THE SFC MASS FIELDS OVER THE CENTRAL CONUS...BUT FOR GFS
ON THE DRY SIDE WITH SFC DEW POINTS NEAR/WEST OF THE SFC RIDGE AXIS.
PER WV IMAGERY MODELS LOOKED GOOD WITH THE SHORTWAVE DETAILS OVER
NOAM. A MODEL CONSENSUS LOOKED GOOD WITH THE 12-18Z PRECIP OVER THE
NORTHERN CONUS. GENERALLY FAVORED THE MODEL/ENSEMBLE CONSENSUS...
WEIGHTED A BIT TOWARD THE ECMWF WITH ITS BETTER RUN-TO-RUN
CONSISTENCY. SHORT-TERM FCST CONFIDENCE REMAINS GOOD THIS CYCLE.
FOR THE SHORT TERM...MAIN WEATHER OF CONCERN IN THE SHORT TERM IS
TONIGHT. STRONGEST OF THE 925-700MB WARM ADVECTION/ISENTROPIC LIFT
SPREAD ACROSS THE FCST AREA THIS EVENING...QUICKLY EXITING/WANING
AFTER MIDNIGHT. MAIN 500-300MB PV ADVECTION WITH THE SHORTWAVE
PASSES ACROSS THE NORTHEAST HALF OF WI THIS EVENING. DEEPEST OF THE
MOISTURE/SATURATION SPREAD ALSO SPREAD ACROSS DURING THE EVENING...
DIMINISHING QUICKLY AFTER MIDNIGHT WITH PASSAGE OF THE 850-700MB
TROUGH AXIS AND SHORTWAVE. MODEL SOUNDINGS INDICATE COLUMN REMAINS
COLD ENOUGH FOR PRECIP AS SNOW ACROSS THE NORTH HALF OF THE FCST
AREA...WHERE THE BETTER/DEEPER SATURATION OCCURS. LIFT/MOISTURE/
SATURATION GENERALLY ABOVE 850MB...BATTLING LOWER LEVEL DRY AIR IN
PLACE FROM THE RETREATING SFC RIDGE AXIS. GOOD MODEL CONSENSUS WITH
A STRONGER SHORTWAVE AND SOME DEEPER LIFT TO OVERCOME THE LOW LEVEL
DRY AIR OVER THE NORTH END OF THE FCST AREA...WITH SOME -SN ALONG/
NORTH OF HWY 29 BY LATER THIS EVENING. RAISED -SN CHANCES TO 60-70
PERCENT LATER THIS EVENING OVER TAYLOR/NORTHERN CLARK COUNTIES...
TAPERING TO NO PRECIP MENTION OVER THE SOUTHWEST 1/3 OF THE FCST
AREA. A QUICK HALF INCH OR SO OF SNOW POSSIBLE BETWEEN MAINLY 9PM-
MIDNIGHT ALONG/NORTH OF HWY 29. SOME CONCERN FOR -FZDZ AS THE PRECIP
ENDS...BUT APPEARS LOSS OF LIFT OCCURS AT THE SAME TIME AS THE
DECREASING DEPTH OF MOISTURE/LOSS OF ICE CRYSTALS IN THE CLOUDS AS
THE TROUGH AXIS PASSES. THUS LEFT ANY MENTION OF -FZDZ OUT OF GRIDS
FOR NOW. TEMPS TO REMAIN NEARLY STEADY THRU THE EVENING...THEN FALL
LATER TONIGHT WITH LOW LEVEL COLD ADVECTION AND DECREASE OF CLOUDS.
CLOUDS/SUNSHINE SOMEWHAT IN QUESTION FOR SUNDAY AS MODELS TRY TO
WRAP SOME 925-850MB MOISTURE SOUTHEAST INTO THE FCST AREA. THIS
MOISTURE IS THEN PUSHED EAST OF THE AREA FOR SUN NIGHT/MON AS SFC-
700MB RIDGING BUILDS INTO THE UPPER MIDWEST. GENERALLY LEFT SKIES
PARTLY CLOUDY THESE PERIODS GIVEN MODEL STRUGGLE WITH LOWER LEVEL
MOISTURE/RH THIS TIME OF YEAR. THE SFC-700MB RIDGE AXIS SLIDES
ACROSS THE REGION MON NIGHT...WITH WHAT SHOULD BE A DEEP...DRY
AIRMASS AND LIGHT WINDS. ANOTHER COLDER NIGHT MON NIGHT WITH THE
LIGHT WINDS AND CLEAR OR MOSTLY CLEAR SKIES. HGTS ALOFT FALL TUE
WITH APPROACH OF SOME MORE SHORTWAVE ENERGY CHANNELED IN THE
NORTHWEST FLOW. ANOTHER SFC-700MB FRONT/TROUGH APPROACHES ON TUE
WITH AN INCREASE OF MOISTURE/CLOUDS ABOVE 500MB. THIS ONE LOOKS
TO HAVE WEAKER FORCING/LIFT AND LESS MOISTURE THAN THE ONE PASSING
TONIGHT...AND LEFT TUE/TUE NIGHT DRY.
GENERALLY FAVORED A BLEND OF THE NUMERICAL GUIDANCE LOWS/HIGHS FOR
TONIGHT THRU TUE NIGHT GIVEN CONCERNS WITH CLOUD COVER AND LARGE
IMPACT CLOUDS...OR NOT...CAN HAVE ON HIGHS/LOWS THIS TIME OF YEAR.
.LONG TERM...WEDNESDAY THROUGH SATURDAY
300 PM CST SAT NOV 24 2012
MEDIUM RANGE MODEL RUNS OF 24.00Z/24.12Z IN GOOD AGREEMENT ON WED
WITH A BROAD NORTHWEST FLOW ALOFT ACROSS THE UPPER MIDWEST. GFS/
ECMWF OFFER RATHER GOOD RUN-TO-RUN CONSISTENCY WED. AGREEMENT OF
24.00/12Z MODELS REMAINS RATHER GOOD THU/FRI WITH SLOW EASTWARD
PROGRESS AND FLATTENING OF THE WESTERN NOAM RIDGING AS SOME
SHORTWAVE ENERGY MOVES THRU THE FLOW. CONSENSUS GOOD WITH A WEAK
SHORTWAVE TO PASS ACROSS THE MID/UPPER MS VALLEY THU NIGHT...THEN
DIFFER WITH THE SHORTWAVE TIMING/STRENGTH DETAILS BY FRI/SAT. RUN-
TO-RUN CONSISTENCY REMAINS GOOD THU THEN BEGINS TO DEGRADE BY
FRI/SAT. TREND BY SAT IS SLOWER THAN THE 23.00/12Z RUNS WITH THE
NEXT LONGWAVE TROUGH APPROACHING THE WEST COAST...WITH MORE RIDGING
ALOFT TO BE OVER CENTRAL NOAM NEXT WEEKEND. LONG TERM FCST
CONFIDENCE GOOD WED/THU THEN AVERAGE FRI/SAT.
DAYS 4-7 CONTINUE TO LOOK LIKE A RATHER QUIET PERIOD ACROSS THE
REGION WITH SLOWLY RISING HGTS AND RIDGING ALOFT BUILDING OVER
CENTRAL NOAM. CAN HIGH PRESSURE DRIFTS SOUTHEAST OVER THE AREA WED.
A WEAK BUT MOISTURE-STARVED SFC-LOWER LEVEL TROUGH LOOKS TO SLIDE
ACROSS THE AREA THU. DEPENDING ON MODEL...WITH GFS THE STRONGEST...
A SHORTWAVE TO MOVE ACROSS THE REGION THU NIGHT INTO FRI. MAY YET
NEED A SMALL -SN/-RA CHANCE THU NIGHT INTO FRI BUT LEFT THIS DRY FOR
NOW AS GFS LOOKS OVERDONE WITH ITS TROUGH AND SFC LOW...PLUS PLENTY
OF DETAIL DIFFERENCES BY FRI. BETTER CONSENSUS FOR SOUTHERLY FLOW
AND STRONGER LOW LEVEL WARM ADVECTION TO SPREAD ACROSS THE UPPER
MIDWEST SAT. MODELS SHOWING A RATHER RAPID NORTHWARD SPREAD OF GULF
OF MEX MOISTURE. MODELS SEEM TOO FAST WITH THIS AND PER THE MODEL/
ENSEMBLE CONSENSUS WILL LEAVE SAT DRY FOR NOW. STUCK WITH THE
MODEL/ENSEMBLE CONSENSUS OF GRADUALLY WARMING TEMPERATURES IN THE
WED-SAT PERIOD AS WELL.
&&
.AVIATION...THROUGH 06Z MONDAY
1108 PM CST SAT NOV 24 2012
THE SURFACE COLD FRONT HAS PUSHED ABOUT HALF AWAY ACROSS MINNESOTA
THIS EVENING. MID LEVEL CLOUDS ASSOCIATED WITH THE SHORT WAVE
TROUGH WILL BE EXITING THE REGION EARLY IN THE PERIOD ONLY TO BE
REPLACED BY LOWER CLOUDS. UPSTREAM OBSERVATIONS INITIALLY INDICATE
THE CEILINGS SHOULD LOWER TO AROUND 5K FEET AHEAD OF THE
FRONT...BUT THEN ONCE THE FRONT MOVES THROUGH...THESE SHOULD LOWER
TO MVFR. IR FOG PRODUCT SHOWS THIS MVFR DECK IS RATHER EXPANSIVE
COVERING MUCH OF NORTH DAKOTA BUT THE BACK EDGE SEEMS TO BE MOVING
ACROSS SOUTHERN SASKATCHEWAN. THE 25.03Z RAP HAS LOCKED ON TO
THIS MOISTURE AND BRINGS IT INTO THE AREA AND THEN TRAPS IT UNDER
THE LOW LEVEL INVERSION SUGGESTING THE CLOUDS WOULD LINGER THROUGH
MUCH OF SUNDAY. WILL INDICATE THESE CLOUDS COMING INTO BOTH TAF
SITES WITH THE FRONTAL PASSAGE BUT WITH A BACK EDGE VISIBLE ON
THE SATELLITE...WILL SHOW THEM SCATTERING OUT AROUND 18Z BASED ON
THE TIMING OF THE CURRENT MOVEMENT. IF THE CLOUDS DO NOT SCATTERED
OUT SUNDAY MORNING...WOULD THEN EXPECT THEM TO PERSIST INTO SUNDAY
NIGHT AS THE 25.00Z NAM DOES DISSIPATE THE LOW LEVEL INVERSION.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
300 PM CST SAT NOV 24 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...04
AREA FORECAST DISCUSSION
NWS DES MOINES IA
521 AM CST SUN NOV 25 2012
.UPDATE 25/12Z AVIATION DISCUSSION...
.SHORT TERM /TODAY/...
SOMEWHAT COMPLICATED SHORT TERM TODAY AS MODELS NOT HANDLING THE
CLOUD COVER OVER MINNESOTA AT ALL. RAP MODEL HAS A BETTER IDEA THAT
STRATUS HAS FORMED AND HEADING SOUTH INTO THE REGION TODAY.
MEANWHILE THERE IS AN UPPER LEVEL BOUNDARY WITH UPSLOPE CLOUDS AND
LIGHT SNOW THAT IS ALSO CREATING A SHIELD OF CLOUDS SCHEDULED TO
HEAD EAST TOWARDS US LATER TODAY. THE COMBINATION OF SOME CLOUDS
EARLY AND MORE CLOUDS LATER WILL DAMPEN HIGHS TODAY. ALSO...THE
MAIN COLD FRONT NOW OVER NORTHWEST IOWA WILL SLIDE SOUTHEAST TODAY
KEEPING NORTHERN IOWA COOLER THAN THE REST OF THE REGION. HIGHS
THERE SHOULD TOP OUT IN THE MID 30S WHILE...WITH THE HEAD START IN
THE MID 30S...CENTRAL AND SOUTHERN IOWA WILL REACH THE LOWER TO MID
40S BY THE MID AFTERNOON. SOME AREAS MAY SEE AMPLE SUN EARLY TODAY
BUT WITH THICKENING CLOUDS MOST OF THE MORNING NORTH AND WEST/SOUTH
REGIONS LATER IN THE AFTERNOON IT SHOULD BE PARTLY SUNNY AT BEST IN
MANY LOCATIONS. WINDS WILL PICK UP BEHIND THE COLD FRONT AND
INCREASE TO ABOUT 10 TO 20 MPH WITH A FEW HIGHER GUSTS BY 2 TO 4 PM
AND THEN DIMINISH BY EVENING. NO PRECIPITATION IS EXPECTED.
.LONG TERM /TONIGHT THROUGH SATURDAY/...
A ZONAL THE NORTHWEST FLOW WILL REMAIN OVER THE CENTRAL CONUS FOR
THE BULK OF THE FORECAST PERIOD. THERE WILL ALSO BE VERY LITTLE
MOISTURE AROUND. THERE ARE SEVERAL SHORTWAVES IN THE UPPER FLOW AND
A COLD FRONT EXPECTED TO CONTINUE TO PASS EAST TONIGHT WITH LITTLE
FANFARE. COLDER AIR WILL SPILL INTO CENTRAL IOWA FOR MONDAY AND
MONDAY NIGHT. A DECENT SHORTWAVE IS PROGGED BY EVERY MEDIUM RANGE
MODEL TO PASS ACROSS THE STATE VERY LATE SUNDAY NIGHT THROUGH
MONDAY. WHAT IS ALSO INTERESTING IS THAT EVERY MODEL DEEPENS THE
WAVE JUST BEFORE IS SWINGS ACROSS IOWA...PUSHING THE FORCING AND THE
PRECIP A LITTLE FURTHER SOUTH. WITH A PRETTY DRY AIRMASS IN PLACE
AND THE FORCING ROM THE SHORTWAVE NOW SHIFTING SOUTH...I EXPECT
LITTLE MORE THAN FLURRIES ACROSS THE FAR SOUTHWEST AND SOUTH.
SHOULD THIS WAVE NOT DEEPEN AS MUCH OR IF THERE IS MORE MOISTURE
WITH THIS SYSTEM THAN THE MODELS ARE SUGGESTING THEN POPS WILL NEED
TO BE RAISED BUT FOR NOW...FLURRIES WILL COVER THE THREAT.
FOR MONDAY NIGHT THROUGH WEDNESDAY AN UPPER LEVEL RIDGE TRIES TO
ESTABLISH ITSELF OVER THE INTERMOUNTAIN WEST KEEPING A NORTHWEST
FLOW ACROSS THE UPPER MIDWEST. DRY AND SEASONAL TO SLIGHTLY BELOW
NORMAL TEMPERATURES ARE EXPECTED DURING THIS TIME.
MODELS DIVERGE SOME THURSDAY NIGHT INTO THE REMAINDER OF THE
EXTENDED. THE GFS DEVELOPS ANOTHER DECENT SHORTWAVE OVER THE REGION
AND THE GEM IS A LITTLE WEAKER AND FURTHER EAST WITH THIS FEATURE
WHILE THE EURO BARELY HAS A REFLECTION IN A MAINLY ZONAL FLOW. AT
THIS TIME I WILL KEEP THIS PERIOD DRY GIVEN THE GFS/S PROPENSITY FOR
OVERDOING PRECIP AND THE FACT THAT NONE OF THE OTHER MODELS PRODUCE
QPF. HOWEVER...I COULD SEE A CASE FOR PRECIP TO OUR EAST AS THE
WAVE DEEPENS JUST A BIT. FOR DAY 7...MODELS ALL HINT AT YET ANOTHER
SHORTWAVE PUSHING INTO THE UPPER MIDWEST BUT LOCATION AND TIMING ARE
NOT IN AGREEMENT. A SURFACE LOW IS BEING DEPICTED BY THE MODELS BUT
WITH UPPER RIDGING PRETTY MUCH IN PLACE I AM NOT LOOKING FOR A LOT
OF MOISTURE WITH THE SYSTEM SO ONCE AGAIN I WILL KEEP THE FORECAST
DRY UNTIL THERE IS BETTER AGREEMENT WITH MODELS AND I SEE SOME KIND
OF MOISTURE WORKING INTO THE REGION. THE MAIN THING FOR THE WEEKEND
IS THAT TEMPS WILL MODERATE TO READINGS ABOVE NORMAL WITH THE UPPER
RIDGING AND SOME LOWER LEVEL WAA WORKING INTO THE REGION.
&&
.AVIATION...25/12Z
LOW STRATUS MOVING INTO NORTHERN IOWA THIS MORNING. SOME UNCERTAINTY
AS TO HOW FAR SOUTH THE CLOUDS WILL ADVANCE BEFORE SOME EROSION OF
LOWER CLOUDS OCCURS. HOWEVER...COLD AIR ADVECTION ACCOMPANYING CLOUD
DECK WILL PROBABLY INFLUENCE THE STRATUS AND KEEP AREAL COVERAGE
MORE INTACT AS IT HEADS SOUTH. THIS AREA OF CLOUDS WILL REDUCE CIGS
TO AN MVFR CATEGORY AS IT MOVES INTO THE REGION. FARTHER WEST
ANOTHER BAND OF CLOUDS WILL HEAD EAST TODAY INTO IOWA BRINGING CIGS
BUT STILL VFR. WINDS WILL REMAIN OUT OF THE SOUTH OR WEST OVER
SOUTHERN SITES THROUGH 16Z PRIOR TO MAIN COLD FRONT SWINGING ALL
WINDS TO NORTH DIRECTION. THIS WILL HAPPEN NORTH SITES OF KMCW KFOD
AND KALO BETWEEN 12Z TO 15Z AND FROM 16Z TO 19Z FOR KDSM AND KOTM.
CURRENT EXPECTATION IS THAT MVFR CLOUDS OVER MN WILL AFFECT KMCW
KFOD AND KALO BEFORE CIGS LIFT SOMEWHAT ON SOUTHERN EDGE. KDSM AND
KOTM SHOULD REMAIN MAINLY VFR WITH CIGS IN A GENERAL RANGE OF 100 TO
150KFT. FOR A BRIEF WINDOW BETWEEN 12Z AND 15Z THERE AN AREA OF
UNLIMITED CIGS AND VFR CONDITIONS MAY HOLD ALONG AND NEAR THE US 20
CORRIDOR BEFORE LOWER MVFR CLOUDS MOVE INTO THE AREA. AFT 20Z WINDS
WILL BEGIN TO MIX MORE ACROSS THE NORTH AS BUFR SOUNDINGS INDICATE
GUSTS TO 20KTS FOR SEVERAL HOURS PRIOR TO SUNSET. SOUTH SITES WILL
EXPERIENCE LESS INFLUENCE OF HIGHER MIXED GUSTS DUE TO LIGHTER WINDS
NEAR THE INVERSION AT KDSM AND KOTM.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...REV
LONG TERM...FAB
AVIATION...REV
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
524 AM CST SUN NOV 25 2012
.AVIATION...
12Z TAFS FOR KOMA...KLNK...AND KOFK.
DETERIORATING CONDITIONS ARE EXPECTED THROUGH THE TAF CYCLE. MID-
LEVEL CLOUDS ARE EXPECTED TODAY...WITH CIGS LOWERING LATER TODAY
AND ESPECIALLY THIS EVENING. HAVE INCLUDED A PROGRESSION THROUGH
MVFR TO IFR...WITH EARLIER DETERIORATION AT KOFK AND LATEST AT
KLNK. HAVE NOT INCLUDED -SN AT ANY SITES AS CONFIDENCE IS LOW ON
COVERAGE...BUT KOFK WOULD HAVE THE BEST SHOT...LIKELY FROM AROUND
08-12Z. ALSO HAVE NOT INCLUDED CIGS LOWER THAN 1KFT...THOUGH SOME
GUIDANCE SUGGESTS LOWER CIGS ARE POSSIBLE AFTER 06Z. WINDS WILL
GRAUDALLY VEER FROM NORTH-NORTHWEST TO NORTHEASTERLY TODAY...WITH
SPEEDS MAINLY AROUND 10KT.
MAYES
&&
.PREV DISCUSSION... /ISSUED 331 AM CST SUN NOV 25 2012/
DISCUSSION...
THE MAIN FORECAST CONCERN CONTINUES TO CENTER THE THE SHORTWAVE
CURRENTLY LOCATED OVER THE STATE OF WA EARLY THIS MORNING PER IR
SAT IMAGERY. THIS SHORTWAVE TROUGH AND ASSOCIATED FORCING FOR
ASCENT WILL TRACK EAST TODAY...AND ACROSS THE REGION LATE TONIGHT
AND INTO MONDAY MORNING. AHEAD OF THE WAVE...ALONG THE PRE-
EXISTING MID LEVEL THERMAL GRADIENT...WEAK CONFLUENT FLOW WILL
CONTINUE TODAY LEADING TO A GOOD DEAL OF MID AND HIGH LEVEL CLOUDS
FOR THE CNTRL AND NORTHERN FORECAST AREA. THE RAP APPEARS TO HAVE
THE BEST HANDLE ON THE STRATUS DECK OVER THE EASTERN DAKOTAS/MN
THIS MORNING AND THE MODEL INDICATES THE CLOUDS WILL MOVE INTO
NORTHEAST NEB AND WEST CNTRL IA...WHICH SEEMS REASONABLE BUT THIS
IS LIKELY THE FARTHEST SOUTH THE LOW CLOUDS WILL GET TODAY. THE
DEGREE OF LOW LEVEL DRY AIR OVER THE NRN CWA NEAR THE THERMAL
GRADIENT CONTS TO MAKE THE CHANCE OF ANY PRECIP MAKING IT TO THE
SURFACE UNLIKELY TODAY AND WE WILL MAINTAIN THE DRY FORECAST.
A LITTLE BETTER FRONTAL CIRCULATION WILL START TO DEVELOP TONIGHT
AS THE QG FORCING ASSOCIATED WITH THE INCOMING SHORTWAVE STARTS
SPREADING INTO THE AREA. THE ATMOSPHERE ABOVE THE FRONTAL ZONE IS
VERY STABLE THOUGH WITH EPV VALUES ABOVE 1 PVU AND THUS OVERALL
VERTICAL MOTION DUE TO THE 700-750 MB FRONTOGENESIS APPEARS LIKE
IT WILL BE FAIRLY WEAK. NEVERTHELESS WITH THE LONG DURATION OF
PERSISTENT WEAK LIFT THE ATMOSPHERE WILL TRY TO SATURATION FROM
THE TOP DOWN WITH SOME LIGHT SNOW REACHING THE SURFACE IN A FAIRLY
NARROW BAND FROM AROUND BVN/OLU/LNK BY MON MORNING. WE HAVE
CONTINUED TO MENTION SOME HALF INCH SNOW TOTALS IN THIS SMALL
AREA WHERE WE HAVE ALSO INCREASED POPS. WE HAVE LOWERED OR REMOVED
POPS MOST OTHER PLACES WITH JUST SOME FLURRIES POSSIBLE LATE
TONIGHT INTO MON. THE LIGHT SNOW WILL LIKELY LINGER INTO MONDAY
MORNING IN THE PREVIOUSLY MENTIONED BAND BEFORE THE UPPER LEVEL
SHORTWAVE TROUGH QUICKLY EXITS TO THE EAST AND LARGE-SCALE
SUBSIDENCE DEVELOPS BY MON AFTERNOON. THIS SHOULD ACT TO START TO
CLEAR THE CLOUDS BY LATE AFTERNOON FOR A GOOD PART OF THE AREA AS
WEAK SURFACE HIGH PRESSURE BUILDS IN.
NORTHWEST FLOW WILL CONTINUE FOR THE REST OF THE FORECAST PERIOD
BECOMING INCREASINGLY WESTERLY BY LATE IN THE PERIOD. THIS IS A
FAIRLY UNSTABLE UPPER LEVEL PATTERN AND SO CONFIDENCE IN THE
SENSIBLE WEATHER LATE IN THE PERIOD IS PRETTY LOW. THE GFS HAS A
STRONGER SYSTEM MOVING THROUGH THE AREA ON THU BUT THE MODEL
APPEARS TO BE AN OUTLIER WHEN COMPARED TO OTHER GLOBAL GUIDANCE
AND WE WILL DISREGARD FOR NOW. TEMPERATURES WILL SLOWLY WARM
THROUGH THE PERIOD WITH HIGHS/LOWS WELL ABOVE NORMAL BY NEXT
WEEKEND.
BOUSTEAD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
346 AM CST SUN NOV 25 2012
.DISCUSSION.../ISSUED AT 346 AM CST/
PASSAGE OF COLD FRONT HAS AGAIN RESULTED IN FAIRLY WIDESPREAD AREA
OF POST FRONTAL STRATUS ACROSS THE EASTERN DAKOTA AND MINNESOTA. RAP
IS BY FAR THE ONLY SOLUTION THAT HAS ADEQUATELY PORTRAYED THE LOWER
CLOUDS...AND THIS SOLUTION IS ALSO THE MOST DISMAL IN RETAINING
STRATUS FIELD THROUGH THE ENTIRE DAY. THIS SEEMS TO BE A BIT EXTREME
WHEN COMPARING TO SOME PARTIAL CLEARING TRENDS TO THE NORTHWEST...
AND INDICATION OF SOME VERY DRY AIR JUST ABOVE THIS CLOUD DECK.
INVERSION REMAINS FAIRLY STRONG...AND WILL LIKELY TRAP A MAJORITY OF
THIS CLOUD DECK...BUT WILL WORK PARTIAL CLEARING INTO THE NORTHERN
AREAS DURING THE AFTERNOON. CLOUDS IN THE MID LEVEL FRONTAL BOUNDARY
WILL KEEP THE COVERAGE HIGH ACROSS THE SOUTH. HOWEVER...DRY AIR WHICH
CURRENTLY PRECLUDES MUCH OF SOUTHWESTERN SD RADAR RETURNS FROM
REACHING THE GROUND OUTSIDE THE BLACK HILLS...WILL LIKELY HOLD
ENOUGH TO KEEP MAJORITY OF PRECIPITATION OUT OF THE CWA THROUGH THE
LATER TODAY THROUGH EARLY MONDAY TIMEFRAME. FRONTAL CIRCULATION GETS
A LITTLE KICK LATER TONIGHT AS BRITISH COLUMBIA WAVES SLIDES ACROSS
SOUTH DAKOTA...BUT WITH MID LEVEL FRONT AS FAR SOUTH AS IT IS...HARD
TO PICTURE MUCH OF ANY MEASURABLE PRECIPITATION THREAT.
COLDEST LOW LEVEL AIR REMAINS TRAPPED UP BEHIND SECONDARY WAVE
ENERGY WHICH THEN SURGES SOUTHWARD LATER TONIGHT AND ESPECIALLY ON
MONDAY WITH THIRD WAVE CURRENTLY IN BRITISH COLUMBIA SLIDES THROUGH.
TEMPERATURES WITH CLOUDS WILL STRUGGLE TODAY...WITH TEMPS PERHAPS A
SHADE COOLER THAN EARLIER FORECAST. LARGER CHANGE TONIGHT...WITH
STRONGER COLD AIR ADVECTION AGAIN INTO NORTHERN CWA. DESPITE
CLOUDS...SHOULD BE ABLE TO ADVECT THE WAY TO AROUND 10 IN THE
NORTH...AND KEEP LOWER 20S THROUGH THE MISSOURI CORRIDOR. COLD AIR
BECOMES ENTRENCHED ON MONDAY AS SURFACE RIDGE SETTLES IN. QUICK EXIT
OF WAVE WILL ENTICE MID LEVEL BOUNDARY SOUTH QUICKLY IN THE DAY...
WITH JUST A MINIMAL SNOW MENTION IN THE FAR SOUTHWEST. WOULD BE
SURPRISED TO FIND ANYONE WITH A HALF INCH AT THIS POINT IN GREGORY
COUNTY...AND LITTLE OR NONE ELSEWHERE.
PASSAGE OF WAVE SHOULD FINALLY MOTIVATE DECREASE IN CLOUDS DURING
MONDAY...AND THIS MOSTLY CLEAR START ON MONDAY NIGHT WITH CHILLY
RIDGE SETTLING THROUGH SW MN AND NW IA SHOULD ALLOW QUICK DROP...
AND OVERALL A NON DIURNAL TREND WITH INCREASING SOUTH TO SOUTHWEST
GRADIENT.
ANOTHER WAVE PASSING WELL NORTH OF THE AREA IN STRONG NORTHWEST FLOW
ALOFT WILL PUSH ANOTHER COLD FRONT SOUTHWARD TUESDAY AFTERNOON AND
TUESDAY EVENING. THIS SHOULD END UP A BIT MORE OF A GLANCING BLOW
WITH MAIN PUSH OF COLD AIR THROUGH MINNESOTA BY WEDNESDAY MORNING.
ALMOST EVERY FRONT OF LATE HAS BEEN ACCOMPANIED BY A STRATUS PUSH...
AND EXPECT THIS MAY ALSO BE THE CASE ON LATER TUESDAY NIGHT AND
WEDNESDAY. SHOULD NOT HAVE THE STAYING POWER OF RECENT SURGES THOUGH
WITH MORE PROGRESSIVE FEATURES AT LOW LEVELS AS WELL AS DEVELOPING
SOUTHWESTERLY COMPONENT BY LATER WEDNESDAY. WILL BE INTERESTING TO
SEE HOW DISPLACEMENT OF LOW LEVEL COLD AIR PLAYS OUT...WITH 00Z
ECMWF SET TO WARM WELL INTO THE 40S...AND EVEN SOME 50S IN THE FAR
SOUTHWEST.
FOR THE EXTENDED RANGE /WEDNESDAY NIGHT THROUGH SATURDAY/ THE DRY
REGIME LOOKS TO CONTINUE. CHALLENGE CONTINUES TO BE DEGREE OF
SHALLOW COLD INTRUSION AS ANOTHER BOUNDARY EXPECTED TO SLIP
SOUTHWARD WEDNESDAY NIGHT AND THURSDAY. CERTAINLY NOT THE
PRECIPITATION THREAT WHICH CONTINUES TO EVADE THROUGH DAY 7.
COOLING THURSDAY IS PRIMARILY VERY SHALLOW...WITH SOME SOLUTIONS
HARDLY BLINKING AT 850 HPA. MAY BE VERY DIFFICULT TO WARM IN SOME
WESTERN/NORTHERN AREAS ON THURSDAY... WHILE THE SOUTHEAST AHEAD OF
THE WEAK BOUNDARY COULD BE FAIRLY MILD...IF NOT IMPEDED BY STRATUS
DEVELOPMENT. MOST SOLUTIONS THROUGH FRIDAY INDICATE BETWEEN 3 TO 6C
INVERSION STRENGTH FROM 925-850 HPA AS FLOW RETURNS TO SOUTH TO
SOUTHEAST COMPONENT BELOW. THIS COULD MAKE WARMING A CHALLENGE EVEN
ON FRIDAY...AND FOR NOW WILL ADVERTISE ONLY A MODEST WARMING FROM
THURSDAY FOR MOST AREAS...SOMEWHAT MORE TO THE FAR WEST. LOOKS LIKE
THE LARGER POTENTIAL WARMING WILL BE SATURDAY. PERHAPS BY EARLY NEXT
WEEK AS LARGER WESTERN TROUGH BEGINS TO SHIFT EAST...CAN A
SIGNIFICANT PRECIPITATION EVENT EVOLVE. /CHAPMAN
&&
.AVIATION.../FOR THE 12Z TAF ISSUANCE/
MVFR CONDITIONS CAN BE EXPECTED THROUGH A LARGE PORTION OF THE
PERIOD AS WIDESPREAD STRATUS HAS DEVELOPED IN BEHIND THE COLD FRONT
THAT PASSED THROUGH THE TAF SITES LAST NIGHT. RUC KEEPS LOW CLOUDS
IN FOR A LONGER TIME PERIOD THAN OTHER MODELS. FEEL MVFR CIGS
SHOULD START BREAKING UP AT 20Z. VFR CONDITIONS WILL DEVELOP AFTER
THAT TIME - 20Z. NORTHERLY WINDS OF 10 TO 15 MPH CAN BE EXPECTED.
/HEITKAMP
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
MN...NONE.
NE...NONE.
SD...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
533 AM CST SUN NOV 25 2012
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
305 AM CST SUN NOV 25 2012
MAIN FORECAST CONCERNS ARE ON CLOUDS THROUGH THE PERIOD AND
TEMPERATURES.
07Z SURFACE ANALYSIS SHOWS TROUGH RUNNING FROM SOUTH CENTRAL
MINNESOTA...INTO NORTHWEST WISCONSIN. LARGE SHIELD OF STRATO-CUMULUS
SEEN BEHIND IT EXTENDING ALL THE WAY INTO THE DAKOTAS...MOVING
SOUTHEAST TOWARDS THE AREA. SNOW ACROSS CLARK AND TAYLOR COUNTIES
WAS EXITING EASTWARD.
25.00Z MODELS STRUGGLING WITH HANDING OF THE NEAR TERM
STRATO-CUMULUS DECK...WITH THE RAP DOING THE BEST.
OTHERWISE...MODELS IN GOOD AGREEMENT THROUGH THE REMAINDER OF THE
PERIOD.
IN THE NEAR TERM...25.03Z RAP RELATIVE HUMIDITY PROGS SHOW STRATUS
FIELD OVER MINNESOTA TO PUSH ACROSS THE FORECAST AREA TODAY IN THE
WAKE OF THE SURFACE TROUGH. 25.12Z NAM ON THE OTHER HAND SHOWS THIS
STRATUS OVER MAINLY THE NORTHERN SECTIONS. RAP VERIFYING BEST AT 07Z
AND THUS GOING FOR THE MORE PESSIMISTIC CLOUD FORECAST TODAY...WITH
MOSTLY CLOUDY SKIES. WITH THE CLOUDS AND 925MB-700MB COLD
ADVECTION...TEMPERATURES WILL NOT REBOUND MUCH FROM MORNING LOWS AND
THUS DID COOL TEMPERATURES A FEW DEGREES FROM THE PREVIOUS FORECAST
AND THIS INLINE WITH GUIDANCE TRENDS OF BEING COOLER.
HIGH PRESSURE BEGINS TO BUILD INTO THE NORTHERN PLAINS/MINNESOTA
TONIGHT. AS DRIER AIR ADVECTS INTO THE REGION DO EXPECT THE CLOUDS TO
BREAK UP SOMEWHAT...WITH SOME CLEARING LIKELY AS THE NIGHT WEARS
ON. SOME CONCERN THAT LOW LEVEL MOISTURE WILL GET TRAPPED UNDER
THE INVERSION AND THUS SEE VERY LITTLE CLEARING. ALSO CANNOT RULE
OUT A FEW FLURRIES THIS EVENING...BUT DID NOT INCLUDE IN THE GRIDS
AT THIS TIME. EXPECT TEMPERATURES TO DROP INTO THE TEENS...AND
PERHAPS A LITTLE COLDER IN AREAS WHERE SKIES WOULD CLEAR.
THE HIGH THEN SETTLES OVERHEAD MONDAY AND MONDAY NIGHT. WITH
850MB TEMPERATURES RANGING FROM -5 DEGREES ACROSS THE FAR SOUTH TO
-12 DEGREES IN THE NORTH...EXPECT THIS TO BE THE COLDEST DAY OF
THE WEEK...WITH HIGHS ONLY IN THE 20S.
THE HIGH WILL TRANSLATE TO THE SOUTHEAST ON TUESDAY...WITH WARM
ADVECTION ON ITS BACK SIDE AS WINDS COME AROUND TO THE SOUTHWEST.
WITH THE 850MB-700MB WARM ADVECTION...A BAND OF MID LEVEL CLOUDS ARE
EXPECTED TO TRAVERSE THE AREA. WITH 850MB TEMPERATURES IN THE -5 TO
-8 DEGREES CELSIUS RANGE...EXPECT HIGHS IN THE UPPER 20S TO MIDDLE
30S. A SHORTWAVE WILL TRANSLATE ACROSS LAKE SUPERIOR LATE IN THE
DAY...DRAGGING A WEAK SURFACE TROUGH THROUGH THE AREA. THIS WILL BE
NO MORE THAN A WIND SHIFT...WITH ANT PRECIPITATION REMAINING WELL TO
THE NORTH OF THE AREA NEAR THE MAIN WAVE. THE SOUTHWESTERLY WINDS
WILL KEEP TEMPERATURES FROM BOTTOMING OUT TUESDAY NIGHT...WITH LOWS
IN THE TEENS AND 20S.
.LONG TERM...WEDNESDAY THROUGH SATURDAY
305 AM CST SUN NOV 25 2012
NORTHWESTERLY FLOW WITH HIGH PRESSURE AT THE SURFACE ON WEDNESDAY
WILL GIVE WAY TO A MORE ZONAL FLOW FROM THURSDAY THROUGH SATURDAY.
25.00Z GFS AND ECMWF DO DIFFER IN THEIR SOLUTIONS IN HANDLING THE
VARIOUS SHORTWAVES MOVING THROUGH THE FLOW. GFS DEPICTS A SHORTWAVE
IN THE FLOW OVER THE CENTRAL PLAINS ON THURSDAY...WHILE THE ECMWF IS
MUCH WEAKER AND FURTHER SOUTH OVER TEXAS. IN EITHER CASE...SOME
TRANSPORT OF LOW LEVEL MOISTURE MAY WORK ITS WAY NORTHWARD INTO
EASTERN IOWA AND SOUTHERN WISCONSIN THURSDAY NIGHT AND BRING A
SLIGHT CHANCE FOR SOME LIGHT PRECIPITATION TO THE AREA.
OTHERWISE...REMAINDER OF THE FORECAST PERIOD LOOKS DRY...WITH A
GRADUAL WARMING TREND INTO THE WEEKEND. IN FACT BOTH THE ECMWF AND
GFS ARE SHOWING 850MB TEMPERATURES RISING TO 8 TO 10 DEGREES
CELSIUS SATURDAY. THUS EXPECT TEMPERATURES TO WARM INTO THE MIDDLE
TO UPPER 40S AND PERHAPS 50 IN A FEW LOCATIONS.
&&
.AVIATION...TODAY AND TONIGHT
533 AM CST SUN NOV 25 2012
IR SATELLITE SHOWING AN EXPANSIVE MVFR STRATOCUMULUS FIELD
EXTENDING FROM ALONG I-90 NORTHWARD ALL THE WAY UP INTO SOUTHERN
MANITOBA. RAP MODEL LATCHED ONTO THIS CLOUD VERY WELL PER THE
0.5KM RELATIVE HUMIDITY FIELD. THIS MOISTURE/MVFR STRATOCUMULUS
FIELD WILL CONTINUE TO SPILL INTO THE AREA TODAY AND REMAIN TRAPPED
UNDER A SUBSIDENCE INVERSION. THIS SHOULD KEEP THE CLOUDS
ENTRENCHED ACROSS THE AREA THROUGH TONIGHT. HAVE TRENDED THE
25.12Z TAFS MORE PESSIMISTIC/CLOUDY BASED ON THIS SIGNAL. MODELS
ALSO INDICATING A MID-LEVEL TROUGH DROPPING INTO THE AREA THIS
EVENING WHICH COULD SQUEEZE OUT A FEW FLURRIES FROM TIME TO TIME.
MOST OF THE FORCING FROM THIS MID-LEVEL WAVE LOOKS TO BE NORTH OF
THE AREA...SO NOT CONFIDENT ENOUGH AT THIS TIME TO INCLUDE IN THE
TAFS...BUT WILL PASS ONTO THE DAYSHIFT TO ASSESS FURTHER.
OTHERWISE...LOOK FOR A NORTHWEST SURFACE FLOW THROUGH THE PERIOD
WITH SOME GUSTINESS IN THE 15 TO 25 MPH RANGE DURING THE DAY
TODAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
305 AM CST SUN NOV 25 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RABERDING
LONG TERM...RABERDING
AVIATION...DAS
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1139 AM CST SUN NOV 25 2012
.SHORT TERM /TODAY/...
SOMEWHAT COMPLICATED SHORT TERM TODAY AS MODELS NOT HANDLING THE
CLOUD COVER OVER MINNESOTA AT ALL. RAP MODEL HAS A BETTER IDEA THAT
STRATUS HAS FORMED AND HEADING SOUTH INTO THE REGION TODAY.
MEANWHILE THERE IS AN UPPER LEVEL BOUNDARY WITH UPSLOPE CLOUDS AND
LIGHT SNOW THAT IS ALSO CREATING A SHIELD OF CLOUDS SCHEDULED TO
HEAD EAST TOWARDS US LATER TODAY. THE COMBINATION OF SOME CLOUDS
EARLY AND MORE CLOUDS LATER WILL DAMPEN HIGHS TODAY. ALSO...THE
MAIN COLD FRONT NOW OVER NORTHWEST IOWA WILL SLIDE SOUTHEAST TODAY
KEEPING NORTHERN IOWA COOLER THAN THE REST OF THE REGION. HIGHS
THERE SHOULD TOP OUT IN THE MID 30S WHILE...WITH THE HEAD START IN
THE MID 30S...CENTRAL AND SOUTHERN IOWA WILL REACH THE LOWER TO MID
40S BY THE MID AFTERNOON. SOME AREAS MAY SEE AMPLE SUN EARLY TODAY
BUT WITH THICKENING CLOUDS MOST OF THE MORNING NORTH AND WEST/SOUTH
REGIONS LATER IN THE AFTERNOON IT SHOULD BE PARTLY SUNNY AT BEST IN
MANY LOCATIONS. WINDS WILL PICK UP BEHIND THE COLD FRONT AND
INCREASE TO ABOUT 10 TO 20 MPH WITH A FEW HIGHER GUSTS BY 2 TO 4 PM
AND THEN DIMINISH BY EVENING. NO PRECIPITATION IS EXPECTED.
.LONG TERM /TONIGHT THROUGH SATURDAY/...
A ZONAL THE NORTHWEST FLOW WILL REMAIN OVER THE CENTRAL CONUS FOR
THE BULK OF THE FORECAST PERIOD. THERE WILL ALSO BE VERY LITTLE
MOISTURE AROUND. THERE ARE SEVERAL SHORTWAVES IN THE UPPER FLOW AND
A COLD FRONT EXPECTED TO CONTINUE TO PASS EAST TONIGHT WITH LITTLE
FANFARE. COLDER AIR WILL SPILL INTO CENTRAL IOWA FOR MONDAY AND
MONDAY NIGHT. A DECENT SHORTWAVE IS PROGGED BY EVERY MEDIUM RANGE
MODEL TO PASS ACROSS THE STATE VERY LATE SUNDAY NIGHT THROUGH
MONDAY. WHAT IS ALSO INTERESTING IS THAT EVERY MODEL DEEPENS THE
WAVE JUST BEFORE IS SWINGS ACROSS IOWA...PUSHING THE FORCING AND THE
PRECIP A LITTLE FURTHER SOUTH. WITH A PRETTY DRY AIRMASS IN PLACE
AND THE FORCING ROM THE SHORTWAVE NOW SHIFTING SOUTH...I EXPECT
LITTLE MORE THAN FLURRIES ACROSS THE FAR SOUTHWEST AND SOUTH.
SHOULD THIS WAVE NOT DEEPEN AS MUCH OR IF THERE IS MORE MOISTURE
WITH THIS SYSTEM THAN THE MODELS ARE SUGGESTING THEN POPS WILL NEED
TO BE RAISED BUT FOR NOW...FLURRIES WILL COVER THE THREAT.
FOR MONDAY NIGHT THROUGH WEDNESDAY AN UPPER LEVEL RIDGE TRIES TO
ESTABLISH ITSELF OVER THE INTERMOUNTAIN WEST KEEPING A NORTHWEST
FLOW ACROSS THE UPPER MIDWEST. DRY AND SEASONAL TO SLIGHTLY BELOW
NORMAL TEMPERATURES ARE EXPECTED DURING THIS TIME.
MODELS DIVERGE SOME THURSDAY NIGHT INTO THE REMAINDER OF THE
EXTENDED. THE GFS DEVELOPS ANOTHER DECENT SHORTWAVE OVER THE REGION
AND THE GEM IS A LITTLE WEAKER AND FURTHER EAST WITH THIS FEATURE
WHILE THE EURO BARELY HAS A REFLECTION IN A MAINLY ZONAL FLOW. AT
THIS TIME I WILL KEEP THIS PERIOD DRY GIVEN THE GFS/S PROPENSITY FOR
OVERDOING PRECIP AND THE FACT THAT NONE OF THE OTHER MODELS PRODUCE
QPF. HOWEVER...I COULD SEE A CASE FOR PRECIP TO OUR EAST AS THE
WAVE DEEPENS JUST A BIT. FOR DAY 7...MODELS ALL HINT AT YET ANOTHER
SHORTWAVE PUSHING INTO THE UPPER MIDWEST BUT LOCATION AND TIMING ARE
NOT IN AGREEMENT. A SURFACE LOW IS BEING DEPICTED BY THE MODELS BUT
WITH UPPER RIDGING PRETTY MUCH IN PLACE I AM NOT LOOKING FOR A LOT
OF MOISTURE WITH THE SYSTEM SO ONCE AGAIN I WILL KEEP THE FORECAST
DRY UNTIL THERE IS BETTER AGREEMENT WITH MODELS AND I SEE SOME KIND
OF MOISTURE WORKING INTO THE REGION. THE MAIN THING FOR THE WEEKEND
IS THAT TEMPS WILL MODERATE TO READINGS ABOVE NORMAL WITH THE UPPER
RIDGING AND SOME LOWER LEVEL WAA WORKING INTO THE REGION.
&&
.AVIATION...25/18Z
MAIN FORECAST PROBLEM IS WITH THE STRATOCU OVER NRN IA. IT WILL
ONLY AFFECT THE KFOD AND KMCW AREA EARLY IN THE PERIOD AS IT THINS
OUT. DON`T EXPECT TO SEE IT PROGRESS SWD. MID AND HIGH CLOUDS WILL
HOLD THROUGH THE NIGHT INTO MON. SOME LOWERING TONIGHT...BUT CIGS
REMAINING ABOVE 050. LIGHT NW-NLY WINDS THROUGH THE FORECAST PERIOD.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...REV
LONG TERM...FAB
AVIATION...REV
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
430 PM EST SUN NOV 25 2012
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 428 PM EST SUN NOV 25 2012
WV IMAGERY AND RUC ANALYSIS INDICATED WNW MID/UPPER LEVEL FLOW
THROUGH THE NRN CONUS. A SHORTWAVE TROUGH EXTENDED FROM NRN ONTARIO
(NEAR CYGQ) INTO NRN WI. A WEAKER UPSTREAM SHRTWV WAS LOCATED OVER
SW MANITOBA. AT THE SFC...LOW PRES WAS LOCATED JUST NORTHEAST OF
LAKE SUPERIOR RESULTING IN WNW LOW LEVEL WINDS. CYCLONIC FLOW AND
ABUNDANT 850-700 MB MOISTURE IN THE WAKE OF THE LOW ALONG WITH 850
MB TEMPS IN THE -11C TO -14C RANGE SUPPORTED AN INCREASE IN LES BAND
INTENSITY. THE STRONGEST BANDS WERE LOCATED NEAR HOUGHTON AND INTO THE
ERN CWA JUST TO THE EAST OF MUNISING.
MAIN FCST CONCERNS ARE LES TRENDS.
EXPECT LES TO CONTINUE FOR LOCATIONS FAVORED BY A 290-310
FLOW...INCLUDING MOST OF THE WRN CWA AND LOCATIONS FROM MUNISING
EASTWARD. THE HIGH RES MODELS IN AGREEMENT SHOWING A GRADUAL
VEERING TREND THIS EVENING WHICH SHOULD HELP TO KEEP THE BANDS FOR
IMPACTING NARROW AREAS FOR AN EXTENDED PERIOD OF TIME. THIS SHOULD
ALSO RESULT IN DECREASING LES INTENSITY INTO THE KEWEENAW WITH A LES
FAVORABLE NW FETCH.
THE HIGH RES MODELS WERE ALSO CONSISTENT IN SHOWING A MORE PRONOUNCED
LOW LEVEL CONV ZONE AIDED BY LAKE INDUCED TROUGHING OVER ERN LAKE
SUPERIOR. THIS SHOULD PROVIDE THE FOCUS FOR THE HEAVIES LES LATE
TONIGHT INTO MONDAY AFTERNOON FOR EASTER ALGER AND NORTHWEST
SCHOOLCRAFT COUNTIES.
INVERSION HEIGHTS IN THE 5K TO 7K FOOT RANGE...GREATEST EAST...ALONG
WITH A DEEP PORTION OF THE CONVECTIVE CLOUDS IN THE DENDRITIC GROWTH
ZONE SHOULD KEEP SNOW/WATER RATIOS IN THE HIGHER SIDE...AT OR ABOVE
20/1. OVERALL SNOWFALL AMOUNTS IN THE 6 TO 12 INCH RANGE STILL LOOK
POSSIBLE FOR SOME LOCATIONS IN ALGER/NSCHOOLCRAFT ZONES WHILE 3 TO 7
INCH AMOUNTS ARE MORE LIKELY OVER THE WEST...GREATEST IN THE HIGHER
TERRAIN BTWN HOUGHTON AND BERGLAND. WITH INVERSION HEIGHTS BEGIN
LOWERING FROM WEST TO EAST MONDAY PREVIOUS FCST TIMING WHICH ENDS
THE LES ADVY OVER THE WEST AT 10 AM LOOKS ON TRACK.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 428 PM EST SUN NOV 25 2012
MON NGT...AS A HI PRES RDG AXIS EXTENDING NEWD FM THE ACYC CENTER IN
THE CENTRAL PLAINS APRCHS...THE LLVL FLOW WL SHIFT STEADILY TO A
MORE WSW DIRECTION. WITH THIS BACKING FLOW...SOME HEAVIER SHSN MIGHT
IMPACT THE KEWEENAW FOR A TIME...BUT LIMITED RESIDENCE TIME WITH
STEADILY SHIFTING WINDS AS WELL AS LOWERING INVRN BASE/WARMING H85
TEMPS SHOULD LIMIT OVERALL ACCUMS. OVER THE E...LLVL CNVGC/LES
INTENSITY MIGHT SHARPEN FOR A TIME WITH BACKING LARGER SCALE
FLOW/LAND BREEZE ENHANCED BY NOCTURNAL COOLING OVER THE CENTRAL
CWA...BUT LES BANDS SHOULD SHIFT OFFSHORE BY 12Z TUE. ALTHOUGH SOME
HEAVIER LES MAY LINGER NEAR THE SHORE FM GRAND MARAIS TO WHITEFISH
POINT LONGER THAN THE 03Z EXPIRATION TIME OF THE GOING LES WARNING
FOR ALGER COUNTY...DID NOT MAKE ANY CHANGES TO THE WARNING NOW TO
AVOID POTENTIAL VERIFICATION PENALTY. ALTHOUGH THE BACKING FLOW WL
ADVECT MORE UNMODIFIED COLD AIR INTO THE CWA...INCRSG WAD CLD IN
ADVANCE OF NEXT CLIPPER DISTURBANCE DIGGING SEWD TOWARD THE UPR LKS
WL TEND TO LIMIT THE DIURNAL TEMP FALL SOMEWHAT.
TUE...COLD FNT ASSOCIATED WITH THIS INCOMING CLIPPER SHRTWV/SFC LO
MOVING THRU NW ONTARIO IS PROGGED TO REACH THE WRN CWA BY 00Z WED.
PCPN IN ADVANCE OF THIS FNT WL BE LIMITED BY LLVL DRY AIR/ABSENCE OF
SGNFT MSTR INFLOW...BUT SUSPECT A PERIOD OF HEAVIER SHSN MIGHT
IMPACT THE W LATER IN THE DAY WITH SOME ENHANCEMENT OFF LK SUP IN
LLVL W FLOW WITH H85 TEMPS ARND -10C UNDER DPVA/DEEP LYR QVECTOR
CNVGC. NO MORE THAN CHC POPS WL BE APPROPRIATE OVER THE REST OF THE
CWA EXCEPT FOR THE E...WHERE SOME MOISTENING OF THE LLVLS IN SW FLOW
OFF LK MI WITH SUFFICIENTLY COLD AIR TO GENERATE LES MIGHT RESULT IN
SOME SHSN. GOING FCST DRY WX FOR THE FAR SCENTRAL SEEMS ON TRACK.
TUE NGT/WED...THE COLD FNT IS FCST TO SWING THRU THE UPR LKS AND
USHER IN A VERY CHILLY AIRMASS WITH H85 TEMPS AS LO AS -16C BY 12Z
WED. DESPITE THIS INCOMING CHILL...LES IN THE WAKE OF THE FROPA WL
BE STUNTED SOMEWHAT BY FAIRLY QUICK TRANSITION TO GENERAL ACYC FLOW
UNDER SHARP NVA/DEEP LYR QVECTOR DVGC/SUBSIDENCE THAT IS FCST TO
LOWER INVRN BASE OVER THE W TO BTWN 3-4K FT AGL BY 12Z WED. DESPITE
THESE NEGATIVES...OPTED TO GO WITH LIKELY POPS IN THE FAVORED NW
WIND SN BELTS...ESPECIALLY OVER THE E WITH LONGER FETCH AND SOME LK
NIPIGON PRE MOISTENING...GIVEN SUFFICIENT COLD AIR INFLUX/LK-H85
DELTA T APRCHG 20C. ON WED...THE LES IN THE NW WIND SN BELTS WL
DIMINISH WITH ARRIVAL OF SFC RDG AXIS/LOWERING INVRN BASE TO 2-3K FT
AGL/BACKING LLVL WINDS TOWARD THE W-SW.
EXTENDED...LONGER RANGE MODELS REMAIN VERY CONSISTENT SHOWING A
MAJOR PATTERN CHG LATER THIS COMING WEEK THAT WL FEATURE A ZONAL
FLOW OF UNSEASONABLY WARM PACIFIC AIR NEXT WEEKEND AS TROF IN ERN
CANADA LIFTS TO THE NE. ON THU...COLD CNDN HI PRES OVER ONTARIO
UNDER WNW FLOW ALF WL STILL BE DOMINATING THE UPR LKS...BUT
STRENGTHENING ISENTROPIC ASCENT ASSOCIATED WITH OVERRUNNING OF THE
RETREATING ARCTIC AIRMASS WL RESULT IN INCRSG CLDS TO THE NE OF WARM
FGEN IN THE NRN PLAINS TO LOWER LKS. AFTER THU...SOME VARIANCE
CREEPS INTO THE MODEL BLEND. RECENT ECMWF RUNS HAVE BEEN VERY
CONSISTENT INDICATING SOME -SN MAY DVLP ON THU NGT AND FRI AS THE
WARM FNT MOVES TO THE N. THE ECMWF INDICATES PCPN MAY EVEN
TRANSITION TO SOME -FZDZ AS DEEPER MSTR SHIFTS TO THE N AS LINGERING
NEAR SFC COLD AIR BECOMES SHALLOWER WITH LOWERING WARM FRONTAL INVRN
HGT. ON THE OTHER HAND...THE MAJORITY OF RECENT GFS RUNS SHOW THE
WARM FNT REMAINING FARTHER S AS A WAVE OF LO PRES ASSOCIATED WITH A
STRONGER SHRTWV RIPPLING THRU THE UPR MIDWEST RUNS W-E ALONG THIS
BNDRY. GIVEN THE LARGER SCALE TRENDS TOWARD RISING HGTS IN THE GRT
LKS AND CONSISTENCY OF THE ECMWF...WHICH IS ALSO PREFERRED BY
NCEP...TENDED TO USE THE ECMWF AS A GUIDE FOR PTYPE DURING THIS
TIME. BULK OF MODELS SHOW ANOTHER SHRTWV WL APRCH ON SAT. IF THE
ECMWF IS CORRECT...PCPN SHOULD BE MAINLY RA. ONLY MARITIME POLAR AIR
WL FOLLOW THIS DISTURBANCE FOR SUN UNDER THE ZONAL FLOW ALF...SO ANY
LES ON SUN SHOULD BE MINIMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1242 PM EST SUN NOV 25 2012
MAINLY MVFR CIGS ARE EXPECTED TO PREVAIL THROUGH THE FORECAST PERIOD.
ARRIVAL OF COLDER AIR WILL GENERATE MORE LAKE EFFECT -SHSN THIS
AFTERNOON AND EVENING AT KIWD AND ESPECIALLY AT KCMX WHERE THE
EXPECTED W WIND WILL UPSLOPE. ON THE OTHER HAND...VFR VSBY SHOULD
CONTINUE AT KSAW WITH DOWNSLOPE WIND COMPONENT. AS INCREASINGLY
COLDER AIR MOVES INTO THE UPPER LAKES...LAKE EFFECT -SHSN SHOULD
BECOME HEAVIER AT KIWD AND KCMX LATE AFTN THROUGH TONIGHT WITH IFR
VIS EXPECTED.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 428 PM EST SUN NOV 25 2012
EXPECT NW WINDS TO 30 KTS TONIGHT AS LOW PRESSURE JUST NORTHEAST OF
LAKE SUPERIOR MOVES QUICKLY OFF TO THE EAST. THERE MAY ALSO BE A FEW
GALE GUSTS TO 35 KTS TONIGHT OVER NORTHERN AND EASTERN PORTIONS OF
LK SUPERIOR. WINDS WILL DIMINISH TO 15 TO 25 KT MONDAY AS HIGH
PRESSURE BUILDS INTO THE UPPER MS VALLEY AND THE WESTERN GREAT
LAKES.
AS HI PRES RIDGE MOVES THRU THE UPPER GREAT LAKES ON MON NIGHT...
EXPECT DIMINISHING WINDS BACKING TO THE SW. THIS SW WIND WILL
INCREASE UP TO 25 TO 30 KTS ON TUE AHEAD OF AN APPROACHING COLD
FRONT. FOLLOWING THE FRONTAL PASSAGE ON LATE TUE/TUE NIGHT...PLAN ON
A WIND SHIFT TO THE NW UP TO 30 KTS AS MUCH COLDER AIR MOVES OVER
LAKE SUPERIOR AND ENHANCES MIXING OF THE STRONGER WINDS TO THE
SURFACE. THE APPROACH OF ANOTHER HI PRES WILL BRING DIMINISHING
WINDS FOR WED. WITH RELATIVELY WEAK PRES GRADIENT IN PLACE THEN FOR
THU/FRI...WINDS SHOULD BE UNDER 25 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING UNTIL 10 PM EST MONDAY FOR MIZ006-085.
LAKE EFFECT SNOW ADVISORY UNTIL 5 AM EST TUESDAY FOR MIZ007.
LAKE EFFECT SNOW ADVISORY UNTIL 10 AM EST /9 AM CST/ MONDAY FOR
MIZ002-003-009.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KC
AVIATION...JLB
MARINE...JLB/KC
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
101 PM CST SUN NOV 25 2012
.UPDATE...
MINOR UPDATES TO THE FORECAST EARLIER TODAY TO ADJUSTED
TEMPERATURES DOWNWARD IN THE NORTH AND ACCOUNT FOR MORE CLOUDS
EARLY ON IN THE SOUTH.
&&
.DISCUSSION...
A COUPLE OF SHORTWAVES WILL AFFECT THE FORECAST AREA TODAY AND
TONIGHT. THE STRONGER THETA-E ADVECTION AND PERSISTENT WEAK LIFT
IS RESULTING CLOUDS FOR NORTHCENTRAL INTO EASTERN NEBRASKA AND
WESTERN IOWA. WITH THE STRONGER LIFT TO THE WEST WITH SOME
UPSLOPE COMPONENT RESULTING IN RAIN AND SNOW FOR PARTS OF THE
NEBRASKA PANHANDLE. THE LOWER CIGS HAVE SHIFTED TOWARD VALENTINE
WHERE THEY HAVE 34 DEGREES AND LIGHT SNOW. SOME SPRINKLES OR
FLURRIES WITH SPRINKLES MAY TRY TO DEVELOP THIS AFTERNOON FOR
AREAS NEAR ALBION...VERDIGRE... AND NORFOLK. ADJUSTED TEMPERATURES
DOWN IN THE NORTH DUE TO THE CLOUDCOVER...BUT STILL IN THE 30S TO
LOWER 40S. THE SOUTH WILL SEE MORE BREAKS NEAR THE KANSAS
BORDER...SO HAVE HIGHS IN THE LOWER 50S. THE NEXT WAVE WILL MOVE
INTO SOUTH DAKOTA TONIGHT AND THIS SHOULD FURTHER SATURATED THE
COLUMN WITH EVEN COLDER DENDRITIC TEMPS ALOFT TO WORK WITH...SO
LIGHT SNOW AND FLURRIES SHOULD HAVE A BETTER CHANCE OF REACHING
THE GROUND.
&&
.PREV DISCUSSION... /ISSUED 1225 PM CST SUN NOV 25 2012/
AVIATION...
18Z TAFS FOR KOMA...KLNK...AND KOFK.
VFR CIGS EXPECTED THRU 00Z WITH CIGS FL060-120.
A COUPLE OF SHORTWAVES WILL AFFECT THE AREA DURING THE PERIOD
WITH DETERIORATING CONDITIONS. THE WSR-88D IS SHOWING A BAND OF
PRECIPITATION FROM MONTANA TO NORTHERN NEBRASKA. THE CIGS ARE
LOWERING TO UNDER FL040 AT AINSWORTH AND ARE MVFR/IFR WITH THE
PRECIPITATION REACHING THE GROUND WITH RAIN AND SNOW IN NORTHWEST
NEBRASKA. THE ECHOES MOVING INTO NORTHEAST NEBRASKA ARE CLOUDS OR
VIRGA. WE COULD SEE SOME SPRINKLES OR SPRINKLES MIXED WITH
FLURRIES AT KOFK LATER THIS AFTERNOON AND THIS EVENING. MVFR CIGS
AND -SN POSSIBLE AT KOFK LATER TONIGHT AND MONDAY MORNING. SOME
QUESTION AS TO WHERE FLURRIES/LIGHT SNOW BAND WILL SET UP IF KOMA
OR KLNK WILL BE IN THE BAND...SO FOR NOW TRENDED DOWNWARD WITH CIG
HEIGHTS AFTER 06Z. SURFACE WINDS WILL GENERALLY BE FROM THE NORTH
AT 5 TO 10KTS.
ZAPOTOCNY
PREV DISCUSSION... /ISSUED 331 AM CST SUN NOV 25 2012/
DISCUSSION...
THE MAIN FORECAST CONCERN CONTINUES TO CENTER THE THE SHORTWAVE
CURRENTLY LOCATED OVER THE STATE OF WA EARLY THIS MORNING PER IR
SAT IMAGERY. THIS SHORTWAVE TROUGH AND ASSOCIATED FORCING FOR
ASCENT WILL TRACK EAST TODAY...AND ACROSS THE REGION LATE TONIGHT
AND INTO MONDAY MORNING. AHEAD OF THE WAVE...ALONG THE PRE-
EXISTING MID LEVEL THERMAL GRADIENT...WEAK CONFLUENT FLOW WILL
CONTINUE TODAY LEADING TO A GOOD DEAL OF MID AND HIGH LEVEL CLOUDS
FOR THE CNTRL AND NORTHERN FORECAST AREA. THE RAP APPEARS TO HAVE
THE BEST HANDLE ON THE STRATUS DECK OVER THE EASTERN DAKOTAS/MN
THIS MORNING AND THE MODEL INDICATES THE CLOUDS WILL MOVE INTO
NORTHEAST NEB AND WEST CNTRL IA...WHICH SEEMS REASONABLE BUT THIS
IS LIKELY THE FARTHEST SOUTH THE LOW CLOUDS WILL GET TODAY. THE
DEGREE OF LOW LEVEL DRY AIR OVER THE NRN CWA NEAR THE THERMAL
GRADIENT CONTS TO MAKE THE CHANCE OF ANY PRECIP MAKING IT TO THE
SURFACE UNLIKELY TODAY AND WE WILL MAINTAIN THE DRY FORECAST.
A LITTLE BETTER FRONTAL CIRCULATION WILL START TO DEVELOP TONIGHT
AS THE QG FORCING ASSOCIATED WITH THE INCOMING SHORTWAVE STARTS
SPREADING INTO THE AREA. THE ATMOSPHERE ABOVE THE FRONTAL ZONE IS
VERY STABLE THOUGH WITH EPV VALUES ABOVE 1 PVU AND THUS OVERALL
VERTICAL MOTION DUE TO THE 700-750 MB FRONTOGENESIS APPEARS LIKE
IT WILL BE FAIRLY WEAK. NEVERTHELESS WITH THE LONG DURATION OF
PERSISTENT WEAK LIFT THE ATMOSPHERE WILL TRY TO SATURATION FROM
THE TOP DOWN WITH SOME LIGHT SNOW REACHING THE SURFACE IN A FAIRLY
NARROW BAND FROM AROUND BVN/OLU/LNK BY MON MORNING. WE HAVE
CONTINUED TO MENTION SOME HALF INCH SNOW TOTALS IN THIS SMALL
AREA WHERE WE HAVE ALSO INCREASED POPS. WE HAVE LOWERED OR REMOVED
POPS MOST OTHER PLACES WITH JUST SOME FLURRIES POSSIBLE LATE
TONIGHT INTO MON. THE LIGHT SNOW WILL LIKELY LINGER INTO MONDAY
MORNING IN THE PREVIOUSLY MENTIONED BAND BEFORE THE UPPER LEVEL
SHORTWAVE TROUGH QUICKLY EXITS TO THE EAST AND LARGE-SCALE
SUBSIDENCE DEVELOPS BY MON AFTERNOON. THIS SHOULD ACT TO START TO
CLEAR THE CLOUDS BY LATE AFTERNOON FOR A GOOD PART OF THE AREA AS
WEAK SURFACE HIGH PRESSURE BUILDS IN.
NORTHWEST FLOW WILL CONTINUE FOR THE REST OF THE FORECAST PERIOD
BECOMING INCREASINGLY WESTERLY BY LATE IN THE PERIOD. THIS IS A
FAIRLY UNSTABLE UPPER LEVEL PATTERN AND SO CONFIDENCE IN THE
SENSIBLE WEATHER LATE IN THE PERIOD IS PRETTY LOW. THE GFS HAS A
STRONGER SYSTEM MOVING THROUGH THE AREA ON THU BUT THE MODEL
APPEARS TO BE AN OUTLIER WHEN COMPARED TO OTHER GLOBAL GUIDANCE
AND WE WILL DISREGARD FOR NOW. TEMPERATURES WILL SLOWLY WARM
THROUGH THE PERIOD WITH HIGHS/LOWS WELL ABOVE NORMAL BY NEXT
WEEKEND.
BOUSTEAD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
ZAPOTOCNY
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1225 PM CST SUN NOV 25 2012
.AVIATION...
18Z TAFS FOR KOMA...KLNK...AND KOFK.
VFR CIGS EXPECTED THRU 00Z WITH CIGS FL060-120.
A COUPLE OF SHORTWAVES WILL AFFECT THE AREA DURING THE PERIOD
WITH DETERIORATING CONDITIONS. THE WSR-88D IS SHOWING A BAND OF
PRECIPITATION FROM MONTANA TO NORTHERN NEBRASKA. THE CIGS ARE
LOWERING TO UNDER FL040 AT AINSWORTH AND ARE MVFR/IFR WITH THE
PRECIPITATION REACHING THE GROUND WITH RAIN AND SNOW IN NORTHWEST
NEBRASKA. THE ECHOES MOVING INTO NORTHEAST NEBRASKA ARE CLOUDS OR
VIRGA. WE COULD SEE SOME SPRINKLES OR SPRINKLES MIXED WITH
FLURRIES AT KOFK LATER THIS AFTERNOON AND THIS EVENING. MVFR CIGS
AND -SN POSSIBLE AT KOFK LATER TONIGHT AND MONDAY MORNING. SOME
QUESTION AS TO WHERE FLURRIES/LIGHT SNOW BAND WILL SET UP IF KOMA
OR KLNK WILL BE IN THE BAND...SO FOR NOW TRENDED DOWNWARD WITH CIG
HEIGHTS AFTER 06Z. SURFACE WINDS WILL GENERALLY BE FROM THE NORTH
AT 5 TO 10KTS.
ZAPOTOCNY
&&
.PREV DISCUSSION... /ISSUED 331 AM CST SUN NOV 25 2012/
DISCUSSION...
THE MAIN FORECAST CONCERN CONTINUES TO CENTER THE THE SHORTWAVE
CURRENTLY LOCATED OVER THE STATE OF WA EARLY THIS MORNING PER IR
SAT IMAGERY. THIS SHORTWAVE TROUGH AND ASSOCIATED FORCING FOR
ASCENT WILL TRACK EAST TODAY...AND ACROSS THE REGION LATE TONIGHT
AND INTO MONDAY MORNING. AHEAD OF THE WAVE...ALONG THE PRE-
EXISTING MID LEVEL THERMAL GRADIENT...WEAK CONFLUENT FLOW WILL
CONTINUE TODAY LEADING TO A GOOD DEAL OF MID AND HIGH LEVEL CLOUDS
FOR THE CNTRL AND NORTHERN FORECAST AREA. THE RAP APPEARS TO HAVE
THE BEST HANDLE ON THE STRATUS DECK OVER THE EASTERN DAKOTAS/MN
THIS MORNING AND THE MODEL INDICATES THE CLOUDS WILL MOVE INTO
NORTHEAST NEB AND WEST CNTRL IA...WHICH SEEMS REASONABLE BUT THIS
IS LIKELY THE FARTHEST SOUTH THE LOW CLOUDS WILL GET TODAY. THE
DEGREE OF LOW LEVEL DRY AIR OVER THE NRN CWA NEAR THE THERMAL
GRADIENT CONTS TO MAKE THE CHANCE OF ANY PRECIP MAKING IT TO THE
SURFACE UNLIKELY TODAY AND WE WILL MAINTAIN THE DRY FORECAST.
A LITTLE BETTER FRONTAL CIRCULATION WILL START TO DEVELOP TONIGHT
AS THE QG FORCING ASSOCIATED WITH THE INCOMING SHORTWAVE STARTS
SPREADING INTO THE AREA. THE ATMOSPHERE ABOVE THE FRONTAL ZONE IS
VERY STABLE THOUGH WITH EPV VALUES ABOVE 1 PVU AND THUS OVERALL
VERTICAL MOTION DUE TO THE 700-750 MB FRONTOGENESIS APPEARS LIKE
IT WILL BE FAIRLY WEAK. NEVERTHELESS WITH THE LONG DURATION OF
PERSISTENT WEAK LIFT THE ATMOSPHERE WILL TRY TO SATURATION FROM
THE TOP DOWN WITH SOME LIGHT SNOW REACHING THE SURFACE IN A FAIRLY
NARROW BAND FROM AROUND BVN/OLU/LNK BY MON MORNING. WE HAVE
CONTINUED TO MENTION SOME HALF INCH SNOW TOTALS IN THIS SMALL
AREA WHERE WE HAVE ALSO INCREASED POPS. WE HAVE LOWERED OR REMOVED
POPS MOST OTHER PLACES WITH JUST SOME FLURRIES POSSIBLE LATE
TONIGHT INTO MON. THE LIGHT SNOW WILL LIKELY LINGER INTO MONDAY
MORNING IN THE PREVIOUSLY MENTIONED BAND BEFORE THE UPPER LEVEL
SHORTWAVE TROUGH QUICKLY EXITS TO THE EAST AND LARGE-SCALE
SUBSIDENCE DEVELOPS BY MON AFTERNOON. THIS SHOULD ACT TO START TO
CLEAR THE CLOUDS BY LATE AFTERNOON FOR A GOOD PART OF THE AREA AS
WEAK SURFACE HIGH PRESSURE BUILDS IN.
NORTHWEST FLOW WILL CONTINUE FOR THE REST OF THE FORECAST PERIOD
BECOMING INCREASINGLY WESTERLY BY LATE IN THE PERIOD. THIS IS A
FAIRLY UNSTABLE UPPER LEVEL PATTERN AND SO CONFIDENCE IN THE
SENSIBLE WEATHER LATE IN THE PERIOD IS PRETTY LOW. THE GFS HAS A
STRONGER SYSTEM MOVING THROUGH THE AREA ON THU BUT THE MODEL
APPEARS TO BE AN OUTLIER WHEN COMPARED TO OTHER GLOBAL GUIDANCE
AND WE WILL DISREGARD FOR NOW. TEMPERATURES WILL SLOWLY WARM
THROUGH THE PERIOD WITH HIGHS/LOWS WELL ABOVE NORMAL BY NEXT
WEEKEND.
BOUSTEAD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
ZAPOTOCNY
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
452 PM EST SUN NOV 25 2012
.SYNOPSIS...
LAKE EFFECT SNOWS WILL IMPACT THE TUG HILL PLATEAU REGION
TONIGHT...AND THEN DROP BACK SOUTH TO COVER MORE OF CENTRAL NEW
YORK WITH SNOW SHOWERS FOR THE FIRST HALF OF MONDAY. SNOW SHOWERS
DIMINISH FOR A TIME MONDAY AFTERNOON...BEFORE A FAST MOVING LOW PRESSURE
SYSTEM BRINGS A PERIOD OF LIGHT SNOW AND FLURRIES TO NORTHERN
PENNSYLVANIA AND SOUTHERN NEW YORK LATE MONDAY NIGHT AND EARLY
TUESDAY. TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH MIDWEEK.
&&
.NEAR TERM /THROUGH MONDAY/...
445 PM UPDATE...
HAVE RECEIVED A FEW REPORTS OF OVER SIX INCHES OF SNOW ACROSS
NORTHERN PORTIONS OF ONEIDA COUNTY. LATEST RADAR TRENDS SHOW A
WELL DEVELOPED LAKE BAND EXTENDING INLAND FROM LAKE ONTARIO...WITH
LITTLE INDICATION SNOWS WILL STOP ANYTIME SOON. BAND WILL LIKELY
LIFT NORTH OF THE AREA FOR A TIME LATER THIS EVENING BEFORE
SHIFTING SOUTH ACROSS NORTHERN ONEIDA COUNTY ONCE AGAIN AS WINDS
AGAIN BECOME WESTERLY AFTER MIDNIGHT. THAT SAID...HAVE DECIDED TO
UPGRADE THE ADVISORY TO A WARNING AS ADDITIONAL ROUNDS OF SNOW
COMBINED WITH SNOW THAT IS OCCURRING NOW WILL LIKELY PUSH
ACCUMULATIONS ABOVE WARNING CRITERIA. NEW WSW ALREADY POSTED. WILL
CONTINUE TO MONITOR.
PREVIOUS NEAR TERM DISCUSSION...
MADE SEVERAL CHANGES TO THE FCST FOR TODAY THROUGH TONIGHT.
NAMELY HAD TO ADJUST POPS HIGHER AS UPPER WAVE CAME IN FROM THE
WEST FOR A HIGH OCCURRENCE/LOW QPF EVENT WITH GENERALLY LIGHT
SNOW/FLURRIES ACROSS THE REGION. WITHIN THE GENERAL LIGHT SNOW
AREA REMAINS THE EMBEDDED LAKE BANDS...AND THE ONEIDA CENTRIC BAND
WAS BECOMING RE- ESTABLISHED ON A 280 FLOW PATTERN THIS AFTERNOON.
SOME REPORTS OF 2-3 INCHES HAVE BEEN RECEIVED FROM ROME NORTHWARD
SINCE THIS MORNING. BAND SHOULD BE ABLE TO PRODUCE ANOTHER FEW
INCHES THIS AFTERNOON AND EARLY EVENING BEFORE PULLING JUST NORTH
OF THE COUNTY LATER IN THE EVENING. FOLLOWED OUR LOCAL WRF MODEL
IN REGARDS TO TIMING AND PLACEMENT OF LIFT/MOISTURE AND QPF
FIELDS...ALTHOUGH NAM12 AND RAP MODEL BUFKIT FIELDS ARE
COMPARABLE. THE BAND THEN LOOKS TO COME BACK IN JUST PRIOR TO
DAYBREAK MONDAY WITH ANOTHER FEW INCHES POSSIBLE. SHEAR ALONG WITH
WEAKENING FLOW AND DIURNAL DISRUPTION OF THE LAKE INSTABILITY
PROCESSES ALLOW FOR WEAKENING MONDAY AFTERNOON WITH NOMINAL
ACCUMS.
SEE LITTLE VARIATION IN TEMPERATURES WITH LOWS IN THE UPR 20S
TONIGHT AND HIGHS MONDAY GENERALLY MID 30S.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
NEXT ITEM TO FOCUS ON WILL BE APPROACHING OPEN WAVE AND WEAK LOW
PRESSURE ON MONDAY NIGHT AND EARLY TUESDAY. THIS LOOKS TO BE A
RATHER MINIMAL EVENT WITH SNOW BREAKING OUT OVER THE LOWER OH/TN
VALLEY REGION DUE TO ISENTROPIC LIFT AHEAD OF THE UPPER WAVE WHICH
THEN LIFTS NORTH INTO MAINLY THE SOUTHERN HALF OF NY AND NEPA.
GFS/NAM IN REASONABLE AGREEMENT THAT WE NEED TO SPEED UP TIMING BY
A GOOD 6 HOURS AS WAA PRECIP DOES TEND TO DEVELOP QUICKER AND
THESE TRENDS SUPPORT THAT. WILL BRING IN LIGHT SNOW BETWEEN 06Z-12Z
TUESDAY...WITH A QUICK HITTING EVENT THAT APPEARS TO BE OUT OF THE
PICTURE BY EARLY AFTERNOON. THIS...ALONG WITH MARGINAL TEMPERATURES
AND MINIMAL LIFT SHOULD BE A LIGHT EVENT WITH NOMINAL ACCUMULATIONS
RANGING FROM A DUSTING TO AN INCH...POSSIBLY 2 INCHES IN THE
MOUNTAINS OF NEPA. THE NORTHERN EXTENT LOOKS TO BE AROUND THE
SOUTHERN TIER OF NY...WITH POSSIBLY A FEW FLURRIES UP NORTH.
HIGH PRESSURE THEN BUILDS IN FROM THE SOUTHWEST...BUT BROAD
CYCLONIC FLOW ALOFT AND INCREASING LOW LEVEL MOISTURE ON NWLY LOWER
ATMOSPHERE FLOW SHOULD SPELL A BROAD AREA OF FLURRIES DEVELOPING
BY WEDNESDAY AFTERNOON.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
GFS/ECMWF IN GOOD AGREEMENT THROUGH THURSDAY... THEN SOME
DIFFERENCES DEVELOP WITH THE NEXT SYSTEM APPROACHING THE AREA FROM
THE MIDWEST. WEDNESDAY NIGHT THROUGH THURSDAY WILL BE COLD WITH
SCATTERED SNOW SHOWERS NEAR LAKE ONTARIO... OTHERWISE DRY. THE GFS
BRINGS PRECIPITATION ASSOCIATED WITH THE NEXT SYSTEM FRIDAY NIGHT
AND SATURDAY... WHILE THE ECMWF IS MUCH SLOWER AND MORE AMPLIFIED
WITH THIS SYSTEM... NOT BRINGING ANY PRECIPITATION INTO THE AREA
UNTIL AROUND SUNDAY. AT THIS POINT HAVE GONE WITH THE HPC SCENARIO
WHICH FAVORS THE SLOWER ECMWF. BASED ON THIS HAVE KEPT
PRECIPITATION OUT OF THE FORECAST THROUGH SATURDAY. TEMPERATURES
THURSDAY THROUGH SATURDAY WILL BE NEAR TO SLIGHTLY BELOW NORMAL...
WITH HIGHS MAINLY IN THE 30S AND LOWS IN THE 20S.
&&
.AVIATION /22Z SUNDAY THROUGH FRIDAY/...
A BAND OF LAKE EFFECT SNOW WILL BRING IFR VSBYS AND CIGS TO RME
THROUGH THIS AFTERNOON. THE BAND WILL LIFT NORTH OF RME TONIGHT
THEN WILL COME BACK SOUTH ACROSS THE RME AREA MONDAY MORNING WITH
ANOTHER PERIOD OF IFR VSBYS AND CIGS. THE BAND WILL REMAIN NORTH
OF SYR THROUGH TONIGHT... THEN A PERIOD OF IFR CIGS AND VSBYS WILL
BE POSSIBLE MONDAY MORNING AS THE BAND MOVES BACK TO THE SOUTH.
OTHERWISE... PERIODS OF LIGHT SNOW WILL AFFECT ITH/ELM/BGM THROUGH
THIS AFTERNOON WITH OCCASIONAL IFR VSBYS. THIS LIGHT SNOW WILL END
TOWARD EVENING WITH VFR VSBYS TONIGHT THROUGH MONDAY ALONG WITH
VFR TO OCCASIONAL MVFR CIGS.
MAINLY VFR CONDITIONS CAN BE EXPECTED AT AVP THROUGH MONDAY.
WINDS WILL BE MAINLY FROM THE WEST AT 5 TO 15 KTS TODAY... LESS
THAN 10 KTS TONIGHT AND 5 TO 15 KTS ON MONDAY.
OUTLOOK...
TUE...VFR-MVFR WITH CHC IFR AS STORM SYSTEM SLIDES JUST TO THE
SOUTH...ESPECIALLY AVP AND BGM.
WED...VFR-MVFR WITH CHC IFR IN LAKE SNOW SHOWERS...MAINLY CNTRL NY.
THU...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...LAKE EFFECT SNOW WARNING UNTIL 1 PM EST TUESDAY FOR NYZ009.
&&
$$
SYNOPSIS...JAB
NEAR TERM...CMG/JAB
SHORT TERM...JAB
LONG TERM...MSE
AVIATION...MSE
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
245 PM EST SUN NOV 25 2012
.SYNOPSIS...
LAKE EFFECT SNOWS WILL IMPACT THE TUG HILL PLATEAU REGION
TONIGHT...AND THEN DROP BACK SOUTH TO COVER MORE OF CENTRAL NEW
YORK WITH SNOW SHOWERS FOR THE FIRST HALF OF MONDAY. SNOW SHOWERS
DIMINISH FOR A TIME MONDAY AFTERNOON...BEFORE A FAST MOVING LOW PRESSURE
SYSTEM BRINGS A PERIOD OF LIGHT SNOW AND FLURRIES TO NORTHERN
PENNSYLVANIA AND SOUTHERN NEW YORK LATE MONDAY NIGHT AND EARLY
TUESDAY. TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH MIDWEEK.
&&
.NEAR TERM /THROUGH MONDAY/...
MADE SEVERAL CHANGES TO THE FCST FOR TODAY THROUGH TONIGHT. NAMELY
HAD TO ADJUST POPS HIGHER AS UPPER WAVE CAME IN FROM THE WEST FOR
A HIGH OCCURRANCE/LOW QPF EVENT WITH GENERALLY LIGHT SNOW/FLURRIES
ACROSS THE REGION. WITHIN THE GENERAL LIGHT SNOW AREA REMAINS THE
EMBEDDED LAKE BANDS...AND THE ONEIDA CENTRIC BAND WAS BECOMING RE-
ESTABLISHED ON A 280 FLOW PATTERN THIS AFTERNOON. SOME REPORTS OF
2-3 INCHES HAVE BEEN RECEIVED FROM ROME NORTHWARD SINCE THIS
MORNING. BAND SHOULD BE ABLE TO PRODUCE ANOTHER FEW INCHES THIS
AFTERNOON AND EARLY EVENING BEFORE PULLING JUST NORTH OF THE
COUNTY LATER IN THE EVENING. FOLLOWED OUR LOCAL WRF MODEL IN REGARDS TO
TIMING AND PLACEMENT OF LIFT/MOISTURE AND QPF FIELDS...ALTHOUGH
NAM12 AND RAP MODEL BUFKIT FIELDS ARE COMPARABLE. THE BAND THEN
LOOKS TO COME BACK IN JUST PRIOR TO DAYBREAK MONDAY WITH ANOTHER
FEW INCHES POSSIBLE. SHEAR ALONG WITH WEAKENING FLOW AND DIURNAL
DISRUPTION OF THE LAKE INSTABILITY PROCESSES ALLOW FOR WEAKENING
MONDAY AFTERNOON WITH NOMINAL ACCUMS.
HAVE DECIDED TO STICK WITH THE LAKE SNOW ADVISORY SINCE THIS LOOKS
TO BE A FAIRLY DRAWN OUT EVENT...ALONG WITH AN ANTICIPATED BREAK
IN THE ACTION RIGHT IN THE MIDDLE OF THE EVENT TONIGHT...ALTHOUGH
SOME OVERALL SNOW TOTALS COULD BE CLOSE TO THE LOW WARNING CRITERIA.
SEE LITTLE VARIATION IN TEMPERATURES WITH LOWS IN THE UPR 20S
TONIGHT AND HIGHS MONDAY GENERALLY MID 30S.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
NEXT ITEM TO FOCUS ON WILL BE APPROACHING OPEN WAVE AND WEAK LOW
PRESSURE ON MONDAY NIGHT AND EARLY TUESDAY. THIS LOOKS TO BE A
RATHER MINIMAL EVENT WITH SNOW BREAKING OUT OVER THE LOWER OH/TN
VALLEY REGION DUE TO ISENTROPIC LIFT AHEAD OF THE UPPER WAVE WHICH
THEN LIFTS NORTH INTO MAINLY THE SOUTHERN HALF OF NY AND NEPA.
GFS/NAM IN REASONABLE AGREEMENT THAT WE NEED TO SPEED UP TIMING BY
A GOOD 6 HOURS AS WAA PRECIP DOES TEND TO DEVELOP QUICKER AND
THESE TRENDS SUPPORT THAT. WILL BRING IN LIGHT SNOW BETWEEN 06Z-12Z
TUESDAY...WITH A QUICK HITTING EVENT THAT APPEARS TO BE OUT OF THE
PICTURE BY EARLY AFTERNOON. THIS...ALONG WITH MARGINAL TEMPERATURES
AND MINIMAL LIFT SHOULD BE A LIGHT EVENT WITH NOMINAL ACCUMULATIONS
RANGING FROM A DUSTING TO AN INCH...POSSIBLY 2 INCHES IN THE
MOUNTAINS OF NEPA. THE NORTHERN EXTENT LOOKS TO BE AROUND THE
SOUTHERN TIER OF NY...WITH POSSIBLY A FEW FLURRIES UP NORTH.
HIGH PRESSURE THEN BUILDS IN FROM THE SOUTHWEST...BUT BROAD
CYCLONC FLOW ALOFT AND INCREASING LOW LEVEL MOISTURE ON NWLY LOWER
ATMOSPHERE FLOW SHOULD SPELL A BROAD AREA OF FLURRIES DEVELOPING
BY WEDNESDAY AFTERNOON.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
GFS/ECMWF IN GOOD AGREEMENT THROUGH THURSDAY... THEN SOME
DIFFERENCES DEVELOP WITH THE NEXT SYSTEM APPRAOCHING THE AREA FROM
THE MIDWEST. WEDNESDAY NIGHT THROUGH THURSDAY WILL BE COLD WITH
SCATTERED SNOW SHOWERS NEAR LAKE ONTARIO... OTHERWISE DRY. THE GFS
BRINGS PRECIPITATION ASSOCIATED WITH THE NEXT SYSTEM FRIDAY NIGHT
AND SATURDAY... WHILE THE ECMWF IS MUCH SLOWER AND MORE AMPLIFIED
WITH THIS SYSTEM... NOT BRINGING ANY PRECIPITATION INTO THE AREA
UNTIL AROUND SUNDAY. AT THIS POINT HAVE GONE WITH THE HPC SCENARIO
WHICH FAVORS THE SLOWER ECMWF. BASED ON THIS HAVE KEPT
PRECIPITATIN OUT OF THE FORECAST THROUGH SATURDAY. TEMPERATURES
THURSDAY THROUGH SATURDAY WILL BE NEAR TO SLIGHTLY BELOW NORMAL...
WITH HIGHS MAINLY IN THE 30S AND LOWS IN THE 20S.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
A BAND OF LAKE EFFECT SNOW WILL BRING IFR VSBYS AND CIGS TO RME
THROUGH THIS AFTERNOON. THE BAND WILL LIFT NORTH OF RME TONIGHT
THEN WILL COME BACK SOUTH ACROSS THE RME AREA MONDAY MORNING WITH
ANOTHER PERIOD OF IFR VSBYS AND CIGS. THE BAND WILL REMAIN NORTH
OF SYR THROUGH TONIGHT... THEN A PERIOD OF IFR CIGS AND VSBYS WILL
BE POSSIBLE MONDAY MORNING AS THE BAND MOVES BACK TO THE SOUTH.
OTHERWISE... PERIODS OF LIGHT SNOW WILL AFFECT ITH/ELM/BGM THROUGH
THIS AFTERNOON WITH OCCASIONAL IFR VSBYS. THIS LIGHT SNOW WILL END
TOWARD EVENING WITH VFR VSBYS TONIGHT THROUGH MONDAY ALONG WITH
VFR TO OCCASIONAL MVFR CIGS.
MAINLY VFR CONDITIONS CAN BE EXPECTED AT AVP THROUGH MONDAY.
WINDS WILL BE MAINLY FROM THE WEST AT 5 TO 15 KTS TODAY... LESS
THAN 10 KTS TONIGHT AND 5 TO 15 KTS ON MONDAY.
OUTLOOK...
TUE...VFR-MVFR WITH CHC IFR AS STORM SYSTEM SLIDES JUST TO THE
SOUTH...ESPECIALLY AVP AND BGM.
WED...VFR-MVFR WITH CHC IFR IN LAKE SNOW SHOWERS...MAINLY CNTRL NY.
THU...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...LAKE EFFECT SNOW ADVISORY UNTIL 6 PM EST MONDAY FOR NYZ009.
&&
$$
SYNOPSIS...JAB
NEAR TERM...JAB
SHORT TERM...JAB
LONG TERM...MSE
AVIATION...MSE
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
224 PM EST SUN NOV 25 2012
.SYNOPSIS...
LAKE EFFECT SNOWS WILL IMPACT THE TUG HILL PLATEAU REGION
TONIGHT...AND THEN DROP BACK SOUTH TO COVER MORE OF CENTRAL NEW
YORK WITH SNOW SHOWERS FOR THE FIRST HALF OF MONDAY. SNOW SHOWERS
DIMINISH FOR A TIME MONDAY AFTERNOON...BEFORE A FAST MOVING LOW PRESSURE
SYSTEM BRINGS A PERIOD OF LIGHT SNOW AND FLURRIES TO NORTHERN
PENNSYLVANIA AND SOUTHERN NEW YORK LATE MONDAY NIGHT AND EARLY
TUESDAY. TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH MIDWEEK.
&&
.NEAR TERM /THROUGH MONDAY/...
MADE SEVERAL CHANGES TO THE FCST FOR TODAY THROUGH TONIGHT. NAMELY
HAD TO ADJUST POPS HIGHER AS UPPER WAVE CAME IN FROM THE WEST FOR
A HIGH OCCURRANCE/LOW QPF EVENT WITH GENERALLY LIGHT SNOW/FLURRIES
ACROSS THE REGION. WITHIN THE GENERAL LIGHT SNOW AREA REMAINS THE
EMBEDDED LAKE BANDS...AND THE ONEIDA CENTRIC BAND WAS BECOMING RE-
ESTABLISHED ON A 280 FLOW PATTERN THIS AFTERNOON. SOME REPORTS OF
2-3 INCHES HAVE BEEN RECEIVED FROM ROME NORTHWARD SINCE THIS
MORNING. BAND SHOULD BE ABLE TO PRODUCE ANOTHER FEW INCHES THIS
AFTERNOON AND EARLY EVENING BEFORE PULLING JUST NORTH OF THE
COUNTY LATER IN THE EVENING. FOLLOWED OUR LOCAL WRF MODEL IN REGARDS TO
TIMING AND PLACEMENT OF LIFT/MOISTURE AND QPF FIELDS...ALTHOUGH
NAM12 AND RAP MODEL BUFKIT FIELDS ARE COMPARABLE. THE BAND THEN
LOOKS TO COME BACK IN JUST PRIOR TO DAYBREAK MONDAY WITH ANOTHER
FEW INCHES POSSIBLE. SHEAR ALONG WITH WEAKENING FLOW AND DIURNAL
DISRUPTION OF THE LAKE INSTABILITY PROCESSES ALLOW FOR WEAKENING
MONDAY AFTERNOON WITH NOMINAL ACCUMS.
HAVE DECIDED TO STICK WITH THE LAKE SNOW ADVISORY SINCE THIS LOOKS
TO BE A FAIRLY DRAWN OUT EVENT...ALONG WITH AN ANTICIPATED BREAK
IN THE ACTION RIGHT IN THE MIDDLE OF THE EVENT TONIGHT...ALTHOUGH
SOME OVERALL SNOW TOTALS COULD BE CLOSE TO THE LOW WARNING CRITERIA.
SEE LITTLE VARIATION IN TEMPERATURES WITH LOWS IN THE UPR 20S
TONIGHT AND HIGHS MONDAY GENERALLY MID 30S.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
NEXT ITEM TO FOCUS ON WILL BE APPROACHING OPEN WAVE AND WEAK LOW
PRESSURE ON MONDAY NIGHT AND EARLY TUESDAY. THIS LOOKS TO BE A
RATHER MINIMAL EVENT WITH SNOW BREAKING OUT OVER THE LOWER OH/TN
VALLEY REGION DUE TO ISENTROPIC LIFT AHEAD OF THE UPPER WAVE WHICH
THEN LIFTS NORTH INTO MAINLY THE SOUTHERN HALF OF NY AND NEPA.
GFS/NAM IN REASONABLE AGREEMENT THAT WE NEED TO SPEED UP TIMING BY
A GOOD 6 HOURS AS WAA PRECIP DOES TEND TO DEVELOP QUICKER AND
THESE TRENDS SUPPORT THAT. WILL BRING IN LIGHT SNOW BETWEEN 06Z-12Z
TUESDAY...WITH A QUICK HITTING EVENT THAT APPEARS TO BE OUT OF THE
PICTURE BY EARLY AFTERNOON. THIS...ALONG WITH MARGINAL TEMPERATURES
AND MINIMAL LIFT SHOULD BE A LIGHT EVENT WITH NOMINAL ACCUMULATIONS
RANGING FROM A DUSTING TO AN INCH...POSSIBLY 2 INCHES IN THE
MOUNTAINS OF NEPA. THE NORTHERN EXTENT LOOKS TO BE AROUND THE
SOUTHERN TIER OF NY...WITH POSSIBLY A FEW FLURRIES UP NORTH.
HIGH PRESSURE THEN BUILDS IN FROM THE SOUTHWEST...BUT BROAD
CYCLONC FLOW ALOFT AND INCREASING LOW LEVEL MOISTURE ON NWLY LOWER
ATMOSPHERE FLOW SHOULD SPELL A BROAD AREA OF FLURRIES DEVELOPING
BY WEDNESDAY AFTERNOON.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
THIS PERIOD LOOKS TO BE INITIALLY UNSETTLED AND COLDER THAN
NORMAL WITH A TREND TOWARD GENERALLY FAIR WEATHER AND NEAR NORMAL
TEMPERATURES AGAIN BY LATE IN THE WEEKEND. UNCERTAINTY REMAINS IN
THE DEVELOPMENT OF LOW PRESSURE ALONG THE EAST COAST FOR
TUESDAY...BUT SHOULD THAT OCCUR...ANY LINGERING PRECIPITATION
WOULD BE EXITING THE AREA TUESDAY NIGHT FOLLOWED BY COLDER AIR AND
DESTABILIZING CONDITIONS ACROSS LAKE ONTARIO. THIS WOULD REFOCUS SNOW
SHOWERS ACROSS CENTRAL NY FOR WEDNESDAY AND THURSDAY WITH CLOUDS
AND SOME FLURRIES FOR NEPA. HIGH PRESSURE AND BROAD RIDGING IS THEN
BEING INDICATED BY THE MEDIUM RANGE MODELS AND ENSEMBLE SUITES FOR
FRIDAY THROUGH SUNDAY.
LOWS GENERALLY IN THE 20S WITH HIGHS IN THE 30S.
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
A BAND OF LAKE EFFECT SNOW WILL BRING IFR VSBYS AND CIGS TO RME
THROUGH THIS AFTERNOON. THE BAND WILL LIFT NORTH OF RME TONIGHT
THEN WILL COME BACK SOUTH ACROSS THE RME AREA MONDAY MORNING WITH
ANOTHER PERIOD OF IFR VSBYS AND CIGS. THE BAND WILL REMAIN NORTH
OF SYR THROUGH TONIGHT... THEN A PERIOD OF IFR CIGS AND VSBYS WILL
BE POSSIBLE MONDAY MORNING AS THE BAND MOVES BACK TO THE SOUTH.
OTHERWISE... PERIODS OF LIGHT SNOW WILL AFFECT ITH/ELM/BGM THROUGH
THIS AFTERNOON WITH OCCASIONAL IFR VSBYS. THIS LIGHT SNOW WILL END
TOWARD EVENING WITH VFR VSBYS TONIGHT THROUGH MONDAY ALONG WITH
VFR TO OCCASIONAL MVFR CIGS.
MAINLY VFR CONDITIONS CAN BE EXPECTED AT AVP THROUGH MONDAY.
WINDS WILL BE MAINLY FROM THE WEST AT 5 TO 15 KTS TODAY... LESS
THAN 10 KTS TONIGHT AND 5 TO 15 KTS ON MONDAY.
OUTLOOK...
TUE...VFR-MVFR WITH CHC IFR AS STORM SYSTEM SLIDES JUST TO THE
SOUTH...ESPECIALLY AVP AND BGM.
WED...VFR-MVFR WITH CHC IFR IN LAKE SNOW SHOWERS...MAINLY CNTRL NY.
THU...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...LAKE EFFECT SNOW ADVISORY UNTIL 6 PM EST MONDAY FOR NYZ009.
&&
$$
SYNOPSIS...JAB
NEAR TERM...JAB
SHORT TERM...JAB
LONG TERM...
AVIATION...MSE
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
250 PM CST SUN NOV 25 2012
.DISCUSSION.../ISSUED AT 250 PM CST/
MAIN CHALLENGES TONIGHT LIE IN THE AMOUNT OF CLOUD COVER ACROSS THE
AREA...WITH POTENTIAL IMPACTS ON OVERNIGHT LOWS...AND PRECIPITATION
POTENTIAL IN OUR FAR SOUTHWEST. STRATUS WHICH RESIDED ACROSS THE
AREA EARLIER IN THE DAY HAS NOW DISSIPATED OVER THE ENTIRE CWA.
TEMPERATURES HAVE BEEN A BIT TRICKY WITH BREAKS IN THE CLOUDS
ALLOWING FOR A RELATIVELY RAPID RISE IN TEMPERATURES IN CLEAR
AREAS...THEN TEMPERED BACK OR FALLING SLIGHTLY WITH THE RETURN OF
CLOUDS. CLOUDS ARE BEGINNING TO FILL BACK IN WITH TWO AREAS
CONVERGING FROM THE NORTH AND SOUTH...MID CLOUDS ACROSS THE SOUTH
AND LOWER CLOUDS DROPPING SOUTHWARD OUT OF NORTH DAKOTA AND NORTHERN
SOUTH DAKOTA AT THIS TIME. MAY SEE A RETURN OF STRATUS...AT LEAST IN
OUR EAST TONIGHT...WITH GFS/NAM/AND RAP INDICATING THE PREVIOUSLY
MENTIONED STRATUS TO OUR NORTH ADVECTING SOUTHWARD ON A
NORTH/NORTHWESTERLY LOW LEVEL FLOW.
WHILE WE DID HAVE A COOLER DAY ACROSS THE AREA...EVEN COLDER AIR IS
POISED TO DRAIN INTO THE REGION TONIGHT BEHIND A SHORTWAVE TRACKING
THROUGH THE UPPER MIDWEST AND INTO THE GREAT LAKES REGION OVERNIGHT.
WITH THIS...WE WILL SEE MUCH COLDER LOWS TONIGHT...MADE SOMEWHAT
CHALLENGING BY WHEN/WHERE THERE IS CLOUD COVER TONIGHT. WITH WINDS
REMAINING FAIRLY LIGHT OVERNIGHT...IF ANY CLEARING TAKES PLACE
READINGS WILL DROP RATHER QUICKLY. AT THIS POINT...HAVE LOWS IN THE
LOWER TEENS NORTH...WHERE COLD AIR ADVECTION WILL BE MOST REALIZED
OVERNIGHT...TO THE LOWER 20S THROUGH OUR FAR SOUTH.
AS FAR AS PRECIPITATION POTENTIAL...RADAR IMAGES HAVE SHOWN RETURNS
THROUGH MUCH OF THE DAY FROM SOUTHWESTERN SOUTH DAKOTA INTO
NORTHEASTERN NEBRASKA...INCLUDING OUR FAR SOUTHERN MISSOURI RIVER
CORRIDOR ZONES...IN THE VICINITY OF A MIDLEVEL BOUNDARY...THOUGH
WITH LOW LEVEL DRY AIR IN PLACE THE ONLY LOCALES REPORTING
PRECIPITATION THUS FAR HAVE BEEN OVER SOUTHWESTERN SOUTH DAKOTA AND
NORTH CENTRAL NEBRASKA. KEPT ONLY SMALL CHANCE POPS IN OUR
SOUTHWESTERN AREAS AS A SHORTWAVE TRACKS OUT OF THE NORTHERN ROCKIES
OVERNIGHT...THOUGH STILL APPEARS THAT THE MIDLEVEL BOUNDARY WILL
BEGIN TO WEAKEN AND SAG SOUTHWARD LATE BEFORE THE BETTER UPPER LEVEL
SUPPORT MOVES INTO THE REGION.
THE COLDEST THERMAL PROFILES WILL BE DRAPED ACROSS OUR AREA ON
MONDAY...ESPECIALLY IN OUR NORTHEAST...WITH HIGHS RANGING FROM THE
LOWER 20S OVER THAT AREA TO THE LOWER 30S THROUGH THE MISSOURI
RIVER CORRIDOR. ALL MODEL RH TIME SECTIONS SHOWING CLOUDS EVENTUALLY
CLEARING OUT BY MONDAY AFTERNOON...SO SHOULD SEE MOSTLY SUNNY SKIES
BY THAT TIME OVER AT LEAST THE NORTHERN TWO THIRDS OF OUR CWA. /JM
SPLIT JET ACROSS THE US IS EXPECTED TO FOCUS MAINLY ON THE NORTHERN
BRANCH THROUGHOUT THE WEEK AS THE SOUTHERN BRANCH WEAKENS.
THROUGHOUT THE WEEK...THE NORTHERN BRANCH OF THE JET IS EXPECTED TO
BUCKLE NORTH AS NORTHWEST FLOW TRANSITIONS TO ZONAL FLOW IN THE MID
LEVELS OF THE ATMOSPHERE. THIS WOULD TYPICALLY RESULT IN A WARMING
TREND...HOWEVER...CLOUD COVER WILL LIKELY HAVE THE MAIN EFFECT ON
TEMPERATURES.
A WEAK COLD FRONT WILL MOVE THROUGH THE AREA ON TUESDAY AFTERNOON.
BOUNDARY IS MAINLY FOCUSED IN THE LOWER LEVELS WITH LITTLE IN THE
WAY OF COLD AIR BEHIND THE FRONT. STILL APPEARS AS THOUGH SOME
STRATUS MAY WORK INTO THE FORECAST AREA FROM THE NORTH TUESDAY NIGHT
LIMITING RADIATIONAL IMPACT. WITH WEAK FLOW ACROSS THE AREA ON
WEDNESDAY...WILL BE A STRUGGLE FOR AREAS IN THE EAST TO WARM IF
STATUS IS ABLE TO PENETRATE INTO THE FORECAST AREA. FOR NOW...HAVE
COOLED FORECAST HIGHS IN SOUTHWEST MINNESOTA...CLOSE TO 925 HPA
ISOTHERMAL...THOUGH MAY HAVE TO EXPAND THE COOLING AS CONFIDENCE IN
THE STRATUS INCREASES.
WEDNESDAY NIGHT A WEAK BOUNDARY APPROACHES FROM THE WEST WITH NO
UPPER LEVEL SUPPORT. MODELS HINT THAT THE BOUNDARY MAY STALL ACROSS
WESTERN PORTIONS OF THE FORECAST AREA...LEAVING THE EAST IN MILD
SOUTHERLY FLOW. THE EAST MAY STILL BE DEALING WITH STRATUS
CONCERNS...SO HAVE SQUASHED DIURNAL RANGE A BIT THURSDAY INTO
FRIDAY. OVERALL...HAVE A GRADUAL WARMING TREND AS 925 HPA TEMPS
WARM FROM 5 TOWARDS 10 DEGREES C.
MODELS SHOW ANOTHER COLD FRONT MOVING THROUGH THE AREA LATE ON
SATURDAY...THOUGH THE STRENGTH OF THE FRONT IS UNDER DEBATE. RIGHT
NOW...THE GFS IS MUCH WEAKER WITH THE FRONT THAN THE ECMWF. WHILE
THE MID LEVEL PATTERN IS MORE ACTIVE...MOISTURE STILL APPEARS TO BE
QUITE LIMITED SO KEPT DRY FORECAST THROUGH NEXT WEEKEND.
STILL APPEARS AS THOUGH A MORE SIZABLE SYSTEM WILL WORK THROUGH THE
NORTHERN PLAINS EARLY THE FOLLOWING WEEK...THOUGH MODELS HAVE BEEN
TRENDING NORTH OF THE FORECAST AREA WITH THE MIDLEVEL WAVE.
&&
.AVIATION.../FOR THE 18Z TAF ISSUANCE/
CHALLENGE CONTINUES TO BE COVERAGE/DURATION OF STRATUS ACROSS THE
AREA. MOST MODELS HAVE NOT BEEN HANDLING IT WELL...THOUGH LEANED
CLOSER TO THE RAP MODEL WHICH HAS HANDLED IT BETTER SINCE LAST
NIGHT. CURRENT OBS SHOWING CLOUDS BEGINNING TO BREAK...AND THINK
THIS WILL CONTINUE THROUGH THE AFTERNOON. WILL HAVE TO WATCH SOME
STRATUS LOCATED TO THE NORTH...THROUGH NORTH DAKOTA/FAR NORTHERN
SOUTH DAKOTA...AS THEY TRAVEL SOUTHWARD ON A NORTH/NORTHWESTERLY LOW
LEVEL FLOW. CONFIDENCE IS SOMEWHAT LOW ON IF THESE CLOUDS WILL HOLD
TOGETHER...SO DID NOT INCLUDE IN THE TAFS. MODELS ALSO HINTING OF
SOME STRATUS REDEVELOPMENT TONIGHT...SO WILL BE SOMETHING TO WATCH
FOR.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
MN...NONE.
NE...NONE.
SD...NONE.
&&
$$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1120 AM CST SUN NOV 25 2012
.DISCUSSION.../ISSUED AT 1030 AM CST/
BIGGEST CHALLENGE TODAY REMAINS TO BE HOW LONG STRATUS WILL HOLD
OVER THE AREA. CURRENT OBSERVATIONS/SATELLITE IMAGES REVEAL STRATUS
COVERING THE ENTIRE CWA LATE THIS MORNING...AND WHILE ALMOST ALL
MODELS ARE FINALLY CATCHING ON TO IT...THE RAP HAS HAD THE MOST
CONSISTENCY SINCE LAST NIGHT AND LEANED TOWARD THAT WITH STRATUS
SLOWLY ERODING THROUGH THE DAY. DO SEE SOME THINNING ACROSS OUR
NORTH...THOUGH AM A LITTLE WORRIED ABOUT ADDITIONAL LOW CLOUDS OVER
NORTH DAKOTA WHICH APPEAR TO BE OOZING SOUTHWARD...AND WILL HAVE TO
KEEP WATCH ON THAT THROUGH THE AFTERNOON. IN ANY EVENT...AM
EXPECTING CONSIDERABLE CLOUDINESS THROUGH THE DAY...WITH A FEW PEAKS
OF SUN AT BEST. WITH THE CLOUD COVER...TEMPERATURES HAVE BEEN ONLY
SLOWLY RISING THROUGH THE MORNING...THOUGH THEY STILL APPEAR TO BE
ON TRACK TO EVENTUAL HIGHS IN THE LOWER 30S NORTH TO NEAR 40 SOUTH.
UPDATES OUT.
&&
.AVIATION.../FOR THE 18Z TAF ISSUANCE/
CHALLENGE CONTINUES TO BE COVERAGE/DURATION OF STRATUS ACROSS THE
AREA. MOST MODELS HAVE NOT BEEN HANDLING IT WELL...THOUGH LEANED
CLOSER TO THE RAP MODEL WHICH HAS HANDLED IT BETTER SINCE LAST
NIGHT. CURRENT OBS SHOWING CLOUDS BEGINNING TO BREAK...AND THINK
THIS WILL CONTINUE THROUGH THE AFTERNOON. WILL HAVE TO WATCH SOME
STRATUS LOCATED TO THE NORTH...THROUGH NORTH DAKOTA/FAR NORTHERN
SOUTH DAKOTA...AS THEY TRAVEL SOUTHWARD ON A NORTH/NORTHWESTERLY LOW
LEVEL FLOW. CONFIDENCE IS SOMEWHAT LOW ON IF THESE CLOUDS WILL HOLD
TOGETHER...SO DID NOT INCLUDE IN THE TAFS. MODELS ALSO HINTING OF
SOME STRATUS REDEVELOPMENT TONIGHT...SO WILL BE SOMETHING TO WATCH
FOR.
&&
.PREV DISCUSSION.../ISSUED AT 346 AM CST/
PASSAGE OF COLD FRONT HAS AGAIN RESULTED IN FAIRLY WIDESPREAD AREA
OF POST FRONTAL STRATUS ACROSS THE EASTERN DAKOTA AND MINNESOTA. RAP
IS BY FAR THE ONLY SOLUTION THAT HAS ADEQUATELY PORTRAYED THE LOWER
CLOUDS...AND THIS SOLUTION IS ALSO THE MOST DISMAL IN RETAINING
STRATUS FIELD THROUGH THE ENTIRE DAY. THIS SEEMS TO BE A BIT EXTREME
WHEN COMPARING TO SOME PARTIAL CLEARING TRENDS TO THE NORTHWEST...
AND INDICATION OF SOME VERY DRY AIR JUST ABOVE THIS CLOUD DECK.
INVERSION REMAINS FAIRLY STRONG...AND WILL LIKELY TRAP A MAJORITY OF
THIS CLOUD DECK...BUT WILL WORK PARTIAL CLEARING INTO THE NORTHERN
AREAS DURING THE AFTERNOON. CLOUDS IN THE MID LEVEL FRONTAL BOUNDARY
WILL KEEP THE COVERAGE HIGH ACROSS THE SOUTH. HOWEVER...DRY AIR WHICH
CURRENTLY PRECLUDES MUCH OF SOUTHWESTERN SD RADAR RETURNS FROM
REACHING THE GROUND OUTSIDE THE BLACK HILLS...WILL LIKELY HOLD
ENOUGH TO KEEP MAJORITY OF PRECIPITATION OUT OF THE CWA THROUGH THE
LATER TODAY THROUGH EARLY MONDAY TIMEFRAME. FRONTAL CIRCULATION GETS
A LITTLE KICK LATER TONIGHT AS BRITISH COLUMBIA WAVES SLIDES ACROSS
SOUTH DAKOTA...BUT WITH MID LEVEL FRONT AS FAR SOUTH AS IT IS...HARD
TO PICTURE MUCH OF ANY MEASURABLE PRECIPITATION THREAT.
COLDEST LOW LEVEL AIR REMAINS TRAPPED UP BEHIND SECONDARY WAVE
ENERGY WHICH THEN SURGES SOUTHWARD LATER TONIGHT AND ESPECIALLY ON
MONDAY WITH THIRD WAVE CURRENTLY IN BRITISH COLUMBIA SLIDES THROUGH.
TEMPERATURES WITH CLOUDS WILL STRUGGLE TODAY...WITH TEMPS PERHAPS A
SHADE COOLER THAN EARLIER FORECAST. LARGER CHANGE TONIGHT...WITH
STRONGER COLD AIR ADVECTION AGAIN INTO NORTHERN CWA. DESPITE
CLOUDS...SHOULD BE ABLE TO ADVECT THE WAY TO AROUND 10 IN THE
NORTH...AND KEEP LOWER 20S THROUGH THE MISSOURI CORRIDOR. COLD AIR
BECOMES ENTRENCHED ON MONDAY AS SURFACE RIDGE SETTLES IN. QUICK EXIT
OF WAVE WILL ENTICE MID LEVEL BOUNDARY SOUTH QUICKLY IN THE DAY...
WITH JUST A MINIMAL SNOW MENTION IN THE FAR SOUTHWEST. WOULD BE
SURPRISED TO FIND ANYONE WITH A HALF INCH AT THIS POINT IN GREGORY
COUNTY...AND LITTLE OR NONE ELSEWHERE.
PASSAGE OF WAVE SHOULD FINALLY MOTIVATE DECREASE IN CLOUDS DURING
MONDAY...AND THIS MOSTLY CLEAR START ON MONDAY NIGHT WITH CHILLY
RIDGE SETTLING THROUGH SW MN AND NW IA SHOULD ALLOW QUICK DROP...
AND OVERALL A NON DIURNAL TREND WITH INCREASING SOUTH TO SOUTHWEST
GRADIENT.
ANOTHER WAVE PASSING WELL NORTH OF THE AREA IN STRONG NORTHWEST FLOW
ALOFT WILL PUSH ANOTHER COLD FRONT SOUTHWARD TUESDAY AFTERNOON AND
TUESDAY EVENING. THIS SHOULD END UP A BIT MORE OF A GLANCING BLOW
WITH MAIN PUSH OF COLD AIR THROUGH MINNESOTA BY WEDNESDAY MORNING.
ALMOST EVERY FRONT OF LATE HAS BEEN ACCOMPANIED BY A STRATUS PUSH...
AND EXPECT THIS MAY ALSO BE THE CASE ON LATER TUESDAY NIGHT AND
WEDNESDAY. SHOULD NOT HAVE THE STAYING POWER OF RECENT SURGES THOUGH
WITH MORE PROGRESSIVE FEATURES AT LOW LEVELS AS WELL AS DEVELOPING
SOUTHWESTERLY COMPONENT BY LATER WEDNESDAY. WILL BE INTERESTING TO
SEE HOW DISPLACEMENT OF LOW LEVEL COLD AIR PLAYS OUT...WITH 00Z
ECMWF SET TO WARM WELL INTO THE 40S...AND EVEN SOME 50S IN THE FAR
SOUTHWEST.
FOR THE EXTENDED RANGE /WEDNESDAY NIGHT THROUGH SATURDAY/ THE DRY
REGIME LOOKS TO CONTINUE. CHALLENGE CONTINUES TO BE DEGREE OF
SHALLOW COLD INTRUSION AS ANOTHER BOUNDARY EXPECTED TO SLIP
SOUTHWARD WEDNESDAY NIGHT AND THURSDAY. CERTAINLY NOT THE
PRECIPITATION THREAT WHICH CONTINUES TO EVADE THROUGH DAY 7.
COOLING THURSDAY IS PRIMARILY VERY SHALLOW...WITH SOME SOLUTIONS
HARDLY BLINKING AT 850 HPA. MAY BE VERY DIFFICULT TO WARM IN SOME
WESTERN/NORTHERN AREAS ON THURSDAY... WHILE THE SOUTHEAST AHEAD OF
THE WEAK BOUNDARY COULD BE FAIRLY MILD...IF NOT IMPEDED BY STRATUS
DEVELOPMENT. MOST SOLUTIONS THROUGH FRIDAY INDICATE BETWEEN 3 TO 6C
INVERSION STRENGTH FROM 925-850 HPA AS FLOW RETURNS TO SOUTH TO
SOUTHEAST COMPONENT BELOW. THIS COULD MAKE WARMING A CHALLENGE EVEN
ON FRIDAY...AND FOR NOW WILL ADVERTISE ONLY A MODEST WARMING FROM
THURSDAY FOR MOST AREAS...SOMEWHAT MORE TO THE FAR WEST. LOOKS LIKE
THE LARGER POTENTIAL WARMING WILL BE SATURDAY. PERHAPS BY EARLY NEXT
WEEK AS LARGER WESTERN TROUGH BEGINS TO SHIFT EAST...CAN A
SIGNIFICANT PRECIPITATION EVENT EVOLVE. /CHAPMAN
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
MN...NONE.
NE...NONE.
SD...NONE.
&&
$$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1030 AM CST SUN NOV 25 2012
.DISCUSSION...
BIGGEST CHALLENGE TODAY REMAINS TO BE HOW LONG STRATUS WILL HOLD
OVER THE AREA. CURRENT OBSERVATIONS/SATELLITE IMAGES REVEAL STRATUS
COVERING THE ENTIRE CWA LATE THIS MORNING...AND WHILE ALMOST ALL
MODELS ARE FINALLY CATCHING ON TO IT...THE RAP HAS HAD THE MOST
CONSISTENCY SINCE LAST NIGHT AND LEANED TOWARD THAT WITH STRATUS
SLOWLY ERODING THROUGH THE DAY. DO SEE SOME THINNING ACROSS OUR
NORTH...THOUGH AM A LITTLE WORRIED ABOUT ADDITIONAL LOW CLOUDS OVER
NORTH DAKOTA WHICH APPEAR TO BE OOZING SOUTHWARD...AND WILL HAVE TO
KEEP WATCH ON THAT THROUGH THE AFTERNOON. IN ANY EVENT...AM
EXPECTING CONSIDERABLE CLOUDINESS THROUGH THE DAY...WITH A FEW PEAKS
OF SUN AT BEST. WITH THE CLOUD COVER...TEMPERATURES HAVE BEEN ONLY
SLOWLY RISING THROUGH THE MORNING...THOUGH THEY STILL APPEAR TO BE
ON TRACK TO EVENTUAL HIGHS IN THE LOWER 30S NORTH TO NEAR 40 SOUTH.
UPDATES OUT.
&&
.PREV DISCUSSION.../ISSUED AT 346 AM CST/
PASSAGE OF COLD FRONT HAS AGAIN RESULTED IN FAIRLY WIDESPREAD AREA
OF POST FRONTAL STRATUS ACROSS THE EASTERN DAKOTA AND MINNESOTA. RAP
IS BY FAR THE ONLY SOLUTION THAT HAS ADEQUATELY PORTRAYED THE LOWER
CLOUDS...AND THIS SOLUTION IS ALSO THE MOST DISMAL IN RETAINING
STRATUS FIELD THROUGH THE ENTIRE DAY. THIS SEEMS TO BE A BIT EXTREME
WHEN COMPARING TO SOME PARTIAL CLEARING TRENDS TO THE NORTHWEST...
AND INDICATION OF SOME VERY DRY AIR JUST ABOVE THIS CLOUD DECK.
INVERSION REMAINS FAIRLY STRONG...AND WILL LIKELY TRAP A MAJORITY OF
THIS CLOUD DECK...BUT WILL WORK PARTIAL CLEARING INTO THE NORTHERN
AREAS DURING THE AFTERNOON. CLOUDS IN THE MID LEVEL FRONTAL BOUNDARY
WILL KEEP THE COVERAGE HIGH ACROSS THE SOUTH. HOWEVER...DRY AIR WHICH
CURRENTLY PRECLUDES MUCH OF SOUTHWESTERN SD RADAR RETURNS FROM
REACHING THE GROUND OUTSIDE THE BLACK HILLS...WILL LIKELY HOLD
ENOUGH TO KEEP MAJORITY OF PRECIPITATION OUT OF THE CWA THROUGH THE
LATER TODAY THROUGH EARLY MONDAY TIMEFRAME. FRONTAL CIRCULATION GETS
A LITTLE KICK LATER TONIGHT AS BRITISH COLUMBIA WAVES SLIDES ACROSS
SOUTH DAKOTA...BUT WITH MID LEVEL FRONT AS FAR SOUTH AS IT IS...HARD
TO PICTURE MUCH OF ANY MEASURABLE PRECIPITATION THREAT.
COLDEST LOW LEVEL AIR REMAINS TRAPPED UP BEHIND SECONDARY WAVE
ENERGY WHICH THEN SURGES SOUTHWARD LATER TONIGHT AND ESPECIALLY ON
MONDAY WITH THIRD WAVE CURRENTLY IN BRITISH COLUMBIA SLIDES THROUGH.
TEMPERATURES WITH CLOUDS WILL STRUGGLE TODAY...WITH TEMPS PERHAPS A
SHADE COOLER THAN EARLIER FORECAST. LARGER CHANGE TONIGHT...WITH
STRONGER COLD AIR ADVECTION AGAIN INTO NORTHERN CWA. DESPITE
CLOUDS...SHOULD BE ABLE TO ADVECT THE WAY TO AROUND 10 IN THE
NORTH...AND KEEP LOWER 20S THROUGH THE MISSOURI CORRIDOR. COLD AIR
BECOMES ENTRENCHED ON MONDAY AS SURFACE RIDGE SETTLES IN. QUICK EXIT
OF WAVE WILL ENTICE MID LEVEL BOUNDARY SOUTH QUICKLY IN THE DAY...
WITH JUST A MINIMAL SNOW MENTION IN THE FAR SOUTHWEST. WOULD BE
SURPRISED TO FIND ANYONE WITH A HALF INCH AT THIS POINT IN GREGORY
COUNTY...AND LITTLE OR NONE ELSEWHERE.
PASSAGE OF WAVE SHOULD FINALLY MOTIVATE DECREASE IN CLOUDS DURING
MONDAY...AND THIS MOSTLY CLEAR START ON MONDAY NIGHT WITH CHILLY
RIDGE SETTLING THROUGH SW MN AND NW IA SHOULD ALLOW QUICK DROP...
AND OVERALL A NON DIURNAL TREND WITH INCREASING SOUTH TO SOUTHWEST
GRADIENT.
ANOTHER WAVE PASSING WELL NORTH OF THE AREA IN STRONG NORTHWEST FLOW
ALOFT WILL PUSH ANOTHER COLD FRONT SOUTHWARD TUESDAY AFTERNOON AND
TUESDAY EVENING. THIS SHOULD END UP A BIT MORE OF A GLANCING BLOW
WITH MAIN PUSH OF COLD AIR THROUGH MINNESOTA BY WEDNESDAY MORNING.
ALMOST EVERY FRONT OF LATE HAS BEEN ACCOMPANIED BY A STRATUS PUSH...
AND EXPECT THIS MAY ALSO BE THE CASE ON LATER TUESDAY NIGHT AND
WEDNESDAY. SHOULD NOT HAVE THE STAYING POWER OF RECENT SURGES THOUGH
WITH MORE PROGRESSIVE FEATURES AT LOW LEVELS AS WELL AS DEVELOPING
SOUTHWESTERLY COMPONENT BY LATER WEDNESDAY. WILL BE INTERESTING TO
SEE HOW DISPLACEMENT OF LOW LEVEL COLD AIR PLAYS OUT...WITH 00Z
ECMWF SET TO WARM WELL INTO THE 40S...AND EVEN SOME 50S IN THE FAR
SOUTHWEST.
FOR THE EXTENDED RANGE /WEDNESDAY NIGHT THROUGH SATURDAY/ THE DRY
REGIME LOOKS TO CONTINUE. CHALLENGE CONTINUES TO BE DEGREE OF
SHALLOW COLD INTRUSION AS ANOTHER BOUNDARY EXPECTED TO SLIP
SOUTHWARD WEDNESDAY NIGHT AND THURSDAY. CERTAINLY NOT THE
PRECIPITATION THREAT WHICH CONTINUES TO EVADE THROUGH DAY 7.
COOLING THURSDAY IS PRIMARILY VERY SHALLOW...WITH SOME SOLUTIONS
HARDLY BLINKING AT 850 HPA. MAY BE VERY DIFFICULT TO WARM IN SOME
WESTERN/NORTHERN AREAS ON THURSDAY... WHILE THE SOUTHEAST AHEAD OF
THE WEAK BOUNDARY COULD BE FAIRLY MILD...IF NOT IMPEDED BY STRATUS
DEVELOPMENT. MOST SOLUTIONS THROUGH FRIDAY INDICATE BETWEEN 3 TO 6C
INVERSION STRENGTH FROM 925-850 HPA AS FLOW RETURNS TO SOUTH TO
SOUTHEAST COMPONENT BELOW. THIS COULD MAKE WARMING A CHALLENGE EVEN
ON FRIDAY...AND FOR NOW WILL ADVERTISE ONLY A MODEST WARMING FROM
THURSDAY FOR MOST AREAS...SOMEWHAT MORE TO THE FAR WEST. LOOKS LIKE
THE LARGER POTENTIAL WARMING WILL BE SATURDAY. PERHAPS BY EARLY NEXT
WEEK AS LARGER WESTERN TROUGH BEGINS TO SHIFT EAST...CAN A
SIGNIFICANT PRECIPITATION EVENT EVOLVE. /CHAPMAN
&&
.AVIATION.../FOR THE 12Z TAF ISSUANCE/
MVFR CONDITIONS CAN BE EXPECTED THROUGH A LARGE PORTION OF THE
PERIOD AS WIDESPREAD STRATUS HAS DEVELOPED IN BEHIND THE COLD FRONT
THAT PASSED THROUGH THE TAF SITES LAST NIGHT. RUC KEEPS LOW CLOUDS
IN FOR A LONGER TIME PERIOD THAN OTHER MODELS. FEEL MVFR CIGS
SHOULD START BREAKING UP AT 20Z. VFR CONDITIONS WILL DEVELOP AFTER
THAT TIME - 20Z. NORTHERLY WINDS OF 10 TO 15 MPH CAN BE EXPECTED.
/HEITKAMP
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
MN...NONE.
NE...NONE.
SD...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1100 AM CST SUN NOV 25 2012
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
305 AM CST SUN NOV 25 2012
MAIN FORECAST CONCERNS ARE ON CLOUDS THROUGH THE PERIOD AND
TEMPERATURES.
07Z SURFACE ANALYSIS SHOWS TROUGH RUNNING FROM SOUTH CENTRAL
MINNESOTA...INTO NORTHWEST WISCONSIN. LARGE SHIELD OF STRATO-CUMULUS
SEEN BEHIND IT EXTENDING ALL THE WAY INTO THE DAKOTAS...MOVING
SOUTHEAST TOWARDS THE AREA. SNOW ACROSS CLARK AND TAYLOR COUNTIES
WAS EXITING EASTWARD.
25.00Z MODELS STRUGGLING WITH HANDING OF THE NEAR TERM
STRATO-CUMULUS DECK...WITH THE RAP DOING THE BEST.
OTHERWISE...MODELS IN GOOD AGREEMENT THROUGH THE REMAINDER OF THE
PERIOD.
IN THE NEAR TERM...25.03Z RAP RELATIVE HUMIDITY PROGS SHOW STRATUS
FIELD OVER MINNESOTA TO PUSH ACROSS THE FORECAST AREA TODAY IN THE
WAKE OF THE SURFACE TROUGH. 25.12Z NAM ON THE OTHER HAND SHOWS THIS
STRATUS OVER MAINLY THE NORTHERN SECTIONS. RAP VERIFYING BEST AT 07Z
AND THUS GOING FOR THE MORE PESSIMISTIC CLOUD FORECAST TODAY...WITH
MOSTLY CLOUDY SKIES. WITH THE CLOUDS AND 925MB-700MB COLD
ADVECTION...TEMPERATURES WILL NOT REBOUND MUCH FROM MORNING LOWS AND
THUS DID COOL TEMPERATURES A FEW DEGREES FROM THE PREVIOUS FORECAST
AND THIS INLINE WITH GUIDANCE TRENDS OF BEING COOLER.
HIGH PRESSURE BEGINS TO BUILD INTO THE NORTHERN PLAINS/MINNESOTA
TONIGHT. AS DRIER AIR ADVECTS INTO THE REGION DO EXPECT THE CLOUDS
TO BREAK UP SOMEWHAT...WITH SOME CLEARING LIKELY AS THE NIGHT WEARS
ON. SOME CONCERN THAT LOW LEVEL MOISTURE WILL GET TRAPPED UNDER THE
INVERSION AND THUS SEE VERY LITTLE CLEARING. ALSO CANNOT RULE OUT A
FEW FLURRIES THIS EVENING...BUT DID NOT INCLUDE IN THE GRIDS AT THIS
TIME. EXPECT TEMPERATURES TO DROP INTO THE TEENS...AND PERHAPS A
LITTLE COLDER IN AREAS WHERE SKIES WOULD CLEAR.
THE HIGH THEN SETTLES OVERHEAD MONDAY AND MONDAY NIGHT. WITH
850MB TEMPERATURES RANGING FROM -5 DEGREES ACROSS THE FAR SOUTH TO
-12 DEGREES IN THE NORTH...EXPECT THIS TO BE THE COLDEST DAY OF
THE WEEK...WITH HIGHS ONLY IN THE 20S.
THE HIGH WILL TRANSLATE TO THE SOUTHEAST ON TUESDAY...WITH WARM
ADVECTION ON ITS BACK SIDE AS WINDS COME AROUND TO THE SOUTHWEST.
WITH THE 850MB-700MB WARM ADVECTION...A BAND OF MID LEVEL CLOUDS ARE
EXPECTED TO TRAVERSE THE AREA. WITH 850MB TEMPERATURES IN THE -5 TO
-8 DEGREES CELSIUS RANGE...EXPECT HIGHS IN THE UPPER 20S TO MIDDLE
30S. A SHORTWAVE WILL TRANSLATE ACROSS LAKE SUPERIOR LATE IN THE
DAY...DRAGGING A WEAK SURFACE TROUGH THROUGH THE AREA. THIS WILL BE
NO MORE THAN A WIND SHIFT...WITH ANT PRECIPITATION REMAINING WELL TO
THE NORTH OF THE AREA NEAR THE MAIN WAVE. THE SOUTHWESTERLY WINDS
WILL KEEP TEMPERATURES FROM BOTTOMING OUT TUESDAY NIGHT...WITH LOWS
IN THE TEENS AND 20S.
.LONG TERM...WEDNESDAY THROUGH SATURDAY
305 AM CST SUN NOV 25 2012
NORTHWESTERLY FLOW WITH HIGH PRESSURE AT THE SURFACE ON WEDNESDAY
WILL GIVE WAY TO A MORE ZONAL FLOW FROM THURSDAY THROUGH SATURDAY.
25.00Z GFS AND ECMWF DO DIFFER IN THEIR SOLUTIONS IN HANDLING THE
VARIOUS SHORTWAVES MOVING THROUGH THE FLOW. GFS DEPICTS A SHORTWAVE
IN THE FLOW OVER THE CENTRAL PLAINS ON THURSDAY...WHILE THE ECMWF IS
MUCH WEAKER AND FURTHER SOUTH OVER TEXAS. IN EITHER CASE...SOME
TRANSPORT OF LOW LEVEL MOISTURE MAY WORK ITS WAY NORTHWARD INTO
EASTERN IOWA AND SOUTHERN WISCONSIN THURSDAY NIGHT AND BRING A
SLIGHT CHANCE FOR SOME LIGHT PRECIPITATION TO THE AREA.
OTHERWISE...REMAINDER OF THE FORECAST PERIOD LOOKS DRY...WITH A
GRADUAL WARMING TREND INTO THE WEEKEND. IN FACT BOTH THE ECMWF AND
GFS ARE SHOWING 850MB TEMPERATURES RISING TO 8 TO 10 DEGREES
CELSIUS SATURDAY. THUS EXPECT TEMPERATURES TO WARM INTO THE MIDDLE
TO UPPER 40S AND PERHAPS 50 IN A FEW LOCATIONS.
&&
.AVIATION...
1100 AM CST SUN NOV 25 2012
AVIATION CONCERNS FOCUS ON THE LOW MVFR STRATUS DECK...HOW LONG IT
WILL LINGER ACROSS THE REGION. LATEST SATELLITE IMAGERY DEPICTS A
BROAD AREA OF LOW STRATUS...MAKING A SLOW PUSH SOUTHEAST ACROSS THE
REGION. SFC OBS UNDER THE CLOUDS PLACED CIG HEIGHTS FROM 1.5-2 KFT.
PIREPS AND VISUAL ID OF THE LAYER SHOWED IT WAS FAIRLY
SHALLOW...ABOUT 1 KFT IN DEPTH. RAP13/NAM12 FAVOR KEEPING THE LOW
RH/CLOUDS ACROSS THE AREA TONIGHT...WITH SUGGESTIONS FROM THE NAM12
THAT IT WOULD HOLD INTO TUE. HOWEVER...SFC WINDS HAVE INCREASED AND
BUFKIT SOUNDINGS PROMOTE MIXING BELOW AN INVERSION AROUND 900 MB.
SO...SEE THE POTENTIAL FOR EROSION OF THE LEADING EDGE OF THE
CLOUDS...ALONG WITH HOLES OPENING UP ELSEWHERE. INDICATION THAT THIS
IS ALREADY HAPPENING IN MOST RECENT SATELLITE IMAGERY. WILL GO WITH
A MIX OF SCT-BKN CONDITIONS FOR THIS AFTERNOON. WOULD EXPECT THE
STRATUS TO FILL IN ANY HOLES LATER TONIGHT...ALA THE BUFKIT
SOUNDINGS. NORTH-SOUTH RUNNING TIME/HEIGHT X-SECTIONS KEEP THE LOW
SATURATION THROUGH MONDAY...BUT SHOW SOME EROSION ON THE SOUTHERN
EXTENT...LIKE TODAY. WILL LEAN TOWARD THE PESSIMISTIC BKN MVFR CIGS
FOR NOW...BUT COULD SEE A BREAKOUT INTO SCT SKIES IN THE AFTERNOON
MON FROM MIXING/DRYING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
305 AM CST SUN NOV 25 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RABERDING
LONG TERM....RABERDING
AVIATION.....RIECK