Forecast Discussions mentioning any of
"HRRR" "RR" "RUC13" "RUC" received at GSD on 12/01/11
AREA FORECAST DISCUSSION
NWS DENVER CO
842 PM MST WED NOV 30 2011
.UPDATE...INITIAL SURGE OF COLD FRONT HAS PUSHED ACROSS MOST OF
NORTHEAST COLORADO THIS EVENING. MOISTURE BEHIND THIS FIRST SURGE WAS
A LITTLE SLOW TO INCREASE PER THE LATEST INTEGRATED PRECIPITABLE
WATER TRENDS FROM GPS. HOWEVER...LATEST MSAS ANALYSIS SHOWS
ANOTHER STRONGER SURGE WITH 3 HOUR PRESSURE RISES OF 7 MB OVER
EASTERN MONTANA...WITH THE LEADING EDGE OF THIS COLDER AIR PUSHING
ACROSS NORTHEAST WYOMING. THIS SHOULD REACH NORTHEAST COLORADO IN
THE LATE NIGHT HOURS. WE HAVE SLOWED DOWN THE DEVELOPMENT OF SNOW
A COUPLE HOURS GIVEN THE LACK OF MOISTURE WITH THE INITIAL
FRONT...BUT OVERALL THE FORECAST IS ON TRACK WITH SNOW DEVELOPING
LATER TONIGHT AND INTENSIFYING BEHIND THE SECONDARY FRONTAL SURGE
AND DEEPENING UPSLOPE. WE HAVE THEREFORE DELAYED THE ONSET OF THE
WINTER STORM WARNING OVER THE PALMER DIVIDE AREA GIVEN THE LATER
ARRIVAL OF MOISTURE. HEAVIEST SNOW IS EXPECTED TO FALL BETWEEN 5 AM
AND 11 AM...WITH A GRADUAL DECREASE FROM NORTH TO SOUTH DURING THE
AFTERNOON.
GOING STORM TOTAL SNOW FORECAST LOOKS ON TRACK AS WELL. WE DID
INCREASE THE SNOW IN THE NORTHERN FOOTHILL JUST A COUPLE INCHES
GIVEN THE JET RELATED FORCING STARTING THE SNOW EARLIER THERE.
&&
.AVIATION...WE HAVE DELAYED THE SNOWFALL JUST A COUPLE HOURS TIL
07Z-10Z GIVEN THE LATER ARRIVAL OF DEEPER MOISTURE. HEAVIEST SNOW
EXPECTED 12Z-17Z WITH A GRADUAL DECREASE FROM 17Z-22Z AND AN END
TO ALL SNOW AROUND 00Z FRIDAY. TOTALS OF 3-6 INCHES LOOKS GOOD...
HEAVIEST AT KBJC-KAPA.
&&
.PREV DISCUSSION... /ISSUED 231 PM MST WED NOV 30 2011/
SHORT TERM...MAIN CONCERN WILL BE UPCOMING WINTER STORM WITH
POSSIBLE SNOW AMOUNTS AND STRENGTH OF THE NORTHERLY WINDS. THE STORM
SYSTEM CAN BE SEEN DEVELOPING OVER THE GREAT BASIN AND IS DIGGING TO
THE SOUTH AND SOUTHEAST TOWARDS SOUTHERN NEVADA. LATEST RUC QG
HEIGHT TENDENCY FIELDS SHOWING THE BEST FALLS ACROSS SOUTHERN NEVADA
AND THIS TRENDS LOOKS TO CONTINUE TONIGHT UNTIL THE LOW BOTTOMS OUT
ACROSS THE CALIFORNIA AND ARIZONA THURSDAY MORNING. THIS TRACK WILL
TAKE THE STRONGEST UPWARD FORCING ACROSS UTAH WITH LESS FORCING AS
YOU MOVE EAST ACROSS COLORADO. SOME WEAK UPSLOPE ALREADY DEVELOPING
OVER EAST COLORADO WITH CYCLOGENESIS ACROSS SOUTHEAST COLORADO.
HOWEVER IT IS QUITE DRY IN THE LOW LEVELS WITH DEWPOINTS IN THE
SINGLE DIGITS AND TEENS AND WILL TAKE A WHILE TO MOISTEN UP. THE
MAIN PRESSURE RISE IS STILL OVER NORTHERN WYOMING SO THIS SHOULD
BRING THE MAIN FRONT INTO DENVER AROUND 03-04Z. BASED ON UPSTREAM
OBSERVATIONS THERE IS A 2-3 HOUR LAG OF THE SNOW STARTING BEHIND THE
FRONT. AIRMASS SHOULD BECOME SATURATED AROUND 09Z AT DENVER AND A
LITTLE LATER OVER OUR SOUTHERN BOUNDARIES AS UPSLOPE DEEPENS. THE
SNOW SHOULD CONTINUE MUCH OF THE DAY WITH A DECREASING TREND OVER
NORTHERN AREAS DURING THE AFTERNOON.
GIVEN LATEST MODEL OUTPUT...ADVISORY AMOUNTS LOOK IN ORDER OVER
MUCH OF THE CWA WHICH HAVE ALREADY BEEN UPDATED IN THE FORECASTS AND
STATEMENTS. SNOW AMOUNTS MAY BE LACKING ACROSS EASTERN ZONE 46 AND
47 ANY MAY BE MORE WIND THEN SNOW. GIVEN THE AMOUNT THIS STILL MAY
CREATE MORE WINDS THAN SNOW BUT STILL MAY CREATE SOME PROBLEMS WITH
SNOW AND WIND. LATEST NAM IS COME DOWN A BIT IN SNOW AMOUNTS A BIT
MORE INLINE WITH GFS/EUROPEAN OUTPUT OF 3-6 INCHES WITH THE HIGHER
AMOUNTS WEST AND SOUTH OF DENVER AND OVER HIGHER EAST SLOPES.
OVERALL THERE IS A SLIGHTLY SLOWER TREND IN SNOW DEVELOPING AND
DELAY THINGS JUST A BIT IN GRIDS.
LONG TERM...STORM SYSTEM TO BE EXITING THE AREA THURSDAY EVENING
WITH IMPROVING CONDITIONS FROM ROUGHLY NORTH TO SOUTH. DID KEEP A
CHANCE OF LIGHT SNOW FOR MOST OF THE AREA WITH THE HIGHEST POPS
ALONG THE PALMER DIVIDE AND LINCOLN COUNTY. WEAK RIDGE STILL
EXPECTED FRIDAY ALTHOUGH AIRMASS WILL BE COLD. MODEL CROSS SECTIONS
INCREASE MOISTURE OVER THE MOUNTAINS DURING THE AFTERNOON AHEAD OF
THE NEXT WEATHER SYSTEM. SOME WEATHER AND POPS LOOK WARRANTED FOR AT
LEAST ZONE 31 AFTER 18Z. NAM PAINTS SOME LIGHT QPF AND SNOW
ACCUMULATIONS ACROSS THE FAR EASTERN ZONES WHILE THE OTHER MODELS
ARE DRY. WILL MAINTAIN THE DRY FORECAST FOR THE PLAINS. SNOW CHANCES
TO INCREASE ACROSS THE MOUNTAINS FRIDAY NIGHT...WITH PERHAPS A
SLIGHT CHANCE ACROSS THE LOWER ELEVATIONS. NAM AND GFS OFFER
DIFFERENT SOLUTIONS WITH THIS SYSTEM AS IT CROSS THE AREA SATURDAY.
THE GFS SHOWS MORE WIDESPREAD LIGHT SNOW AMOUNTS WHILE THE NAM
LIMITS THE AMOUNTS TO THE PALMER DIVIDE AS WELL AS THE FOOTHILLS AND
MOUNTAINS. GIVEN THE DISCREPENCIES...FEEL CHANCE POPS MOST AREAS
SEEM REASONABLE. BOTH MODELS DO SHOW SURFACE FRONT MOVING SOUTH
ACROSS THE AREA DURING THE MORNING. THIS STORM TO EXIT THE AREA BY
THE EVENING...WITH RIDGE BUILDING OVER THE GREAT BASIN AND NORTHWEST
FLOW ALOFT ACROSS COLORADO. MODELS CONTINUE TO HINT AT ANOTHER
DISTURBANCE MOVING SOUTHEAST ACROSS THE AREA SATURDAY NIGHT AND
MONDAY MORNING. THERE APPEARS TO BE ENOUGH LIFT AND MOISTURE TO KEEP
A SLIGHT CHANCE OF SNOW ACROSS THE AREA. OTHERWISE...A MAINLY DRY
NORTHWEST FLOW ALOFT TO PREVAIL THROUGH WEDNESDAY. WITH THE LACK OF
MOISTURE AND LIFT...TOOK OUT ALL MENTION OF MOUNTAIN SNOW MONDAY
AFTERNOON AND TUESDAY. MODELS HINT AT TROUGH MOVING ACROSS THE AREA
WEDNESDAY WITH AN INCREASE IN MOISTURE. ADDED SOME MOUNTAIN POPS
WITH DRY CONDITIONS ELSEWHERE. TEMPERATURES THROUGH THE EXTENDED TO
BE BELOW NORMAL...THOUGH SOME MODERATION ON EXPECTED ON TUESDAY.
AVIATION...A COLD FRONT WILL PASS THROUGH DENVER BETWEEN 03-04Z
GIVEN CURRENT TIMING OF FRONT NOW ACROSS NORTHERN WYOMING.
IT WILL TAKE A WHILE TO MOISTEN UP THE AIRMASS SO THERE WILL BE A
2-3 HOUR LAG FROM FROPA TO SNOWFALL AT LOCAL TERMINALS.
IFR AND ILS CONDITIONS EXPECTED TO DEVELOP BY 09Z WITH SNOW AND
BLOWING SNOW. CONDITIONS WILL SLOWLY IMPROVE DURING THURSDAY
AFTERNOON FROM NORTH TO SOUTH. BEST ESTIMATE OF STORM TOTAL SNOW AT
LOCAL TERMINALS IS 3-6 INCHES...WITH THE HIGHER AMOUNTS AT KAPA/KBJC.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 5 PM MST THURSDAY FOR COZ033>037-
039-040.
WINTER WEATHER ADVISORY UNTIL 2 PM MST THURSDAY FOR COZ038-
042>044-048-049.
WINTER STORM WARNING FROM 3 AM TO 5 PM MST THURSDAY FOR COZ041-
045>047.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....D-L
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
313 PM CST TUE NOV 29 2011
.DISCUSSION...
313 PM CST
MESOSCALE/TONIGHT...
A VERY IMPRESSIVE WATER VAPOR SATELLITE LOOP THIS AFTERNOON
REVEALS THE EXPANSIVE COLD CORE LOW LIFTING NORTHEAST ACROSS THE
APPALACHIANS...JUST GRAZING THE AREA. A WELL-DEFINED DEFORMATION
AREA HAS FILLED IN WITH BANDS OF COLDER AND AT TIMES CONVECTIVE
CLOUD TOPS PROVIDING HEAVIER AND FROZEN PRECIPITATION ACROSS PARTS
OF NORTHERN IN. THE DUAL POLARIZATION RADAR EVEN DETECTED THE
PRECIPITATION TYPE SWITCH AT 7000-9000 FT. THIS HAS BEEN OBSERVED
AT THE GROUND JUST TO THE SOUTH AND EAST OF THE FORECAST AREA IN
LAFAYETTE /WHERE SLUSHY ACCUMULATION HAS OCCURRED ON GRASSY
SURFACES/. THE 13KM RUC SOUNDINGS ACROSS BENTON AND JASPER
COUNTIES CONTINUE TO SHOW A GRADUAL SHRINKING OF THE NEAR-SURFACE
WARM LAYER TO ALLOW FOR A MIX TO MAKE IT TO THE GROUND FOR
POSSIBLY A COUPLE HOURS. THAT COUPLE OF HOURS LOOKS TO BE IT GIVEN
SATELLITE AND SHORT TERM MODEL TRENDS TO SHIFT THE FORCING EAST.
GIVEN THAT ANY TRANSITION WILL BE SO SHORT LIVED AND OVER WARM
GROUND...WILL CANCEL THE WINTER WEATHER ADVISORY.
STRONG NORTHERLY WINDS HAVING GUSTED AS HIGH AS 60 MPH AT THE
CHICAGO CRIB...52 MPH AT GARY...AND 48 MPH AT MIDWAY WILL
GRADUALLY DIMINISH THROUGH THE EVENING WITH THE AREA PINCHED
BETWEEN THE 1001 MB LOW NEAR CLEVELAND AND THE INCOMING 1027 MB
RIDGE. AN AIRCRAFT SOUNDING OUT OF OHARE JUST AFTER 2 PM REVEALED
40 KT WINDS AT THE TOP OF THE CHANNEL...AND NAM AND RUC SOUNDINGS
KEEP SIMILAR SPEEDS WITHIN THE BOUNDARY LAYER UNTIL A COUPLE HOURS
AFTER SUNSET. WITH STILL AN ONSHORE COMPONENT TO THE WIND...WILL
LET THE WIND ADVISORY CONTINUE. A QUICK DECOUPLING LATER IN THE
EVENING SHOULD ALLOW FOR WINDS TO COME DOWN MORE RAPIDLY ACROSS
THE ILLINOIS FORECAST AREA. ASSOCIATED LAKE SHORE FLOODING
CONCERNS WITH THE WIND ALSO CONTINUE GIVEN THE 10 TO 15 FT WAVES
FORECAST...BUT LIKELY WILL NOT LAST AS FAR INTO WEDNESDAY. CLOUDS
SHOULD SCOUR FAIRLY QUICKLY WEST OF CHICAGO THROUGH EARLY
EVENING...THEN MORE SLOWLY DOWNSTREAM OF THE LAKE. WHILE SOME LAKE
ENHANCED CLOUDS MAY OCCUR...FORECAST DEPTHS ARE VERY SHALLOW WITH
DRIER AIR BEING RAKED IN ON THE NORTHERLY WINDS...AND THUS NOT
EXPECTING ANY SHOWERS. WITH FORECAST TEMPERATURES HAVE MADE ONLY
MINOR TWEAKS...WITH READINGS ALMOST RIGHT AT NORMAL ACROSS THE
ENTIRE FORECAST AREA.
MTF
WEDNESDAY THROUGH TUESDAY...
ACTUALLY LOOKING LIKE A DAY OR TWO OF FAIRLY PLEASANT LATE NOVEMBER
WEATHER WEDNESDAY INTO THURSDAY IN WAKE OF TODAY`S SIDESWIPING BY
THE STRONG STORM SYSTEM. WARM AIR ADVECTION WILL COMMENCE WEDNESDAY
AS LOW/MID LEVEL FLOW BEGINS TO BACK IN ADVANCE OF THE NEXT NORTHERN
STREAM SHORTWAVE WHICH WILL BEGIN DROPPING INTO THE NORTHERN PLAINS.
AFTER A CHILLY MORNING TEMPS SHOULD REBOUND NICELY TOMORROW WITH
NEARLY FULL SUNSHINE.
INCREASING MID/HIGH LEVEL CLOUDINESS AND SOUTHWEST WINDS SHOULD KEEP
TEMPS A BIT WARMER TOMORROW NIGHT WHICH WILL THEN PROVIDE FOR A NICE
SPRING BOARD FOR TEMPS THURSDAY TO CLIMB BACK TO SEVERAL DEGREES
ABOVE AVERAGE. COLD FRONT WILL THEN DROP SOUTHWARD ACROSS THE CWA
LATE THURSDAY AFTERNOON/EARLY THURSDAY EVENING. STRONGEST FORCING
WITH THIS WAVE LOOKS TO PASS WELL NORTH/NORTHEAST OF THE AREA AND
WITH SCANT MOISTURE AT BEST AM HAVING A HARD TIME GETTING TOO WORKED
UP OVER OUR SNOW CHANCES THURSDAY NIGHT. ECMWF/GFS BOTH STILL TRYING
TO SPIT OUT A HUNDREDTH OF AN INCH OR SO OF QPF SO HAVE MAINTAINED
THE SLIGHT CHANCE POPS WE HAD GOING...WHICH ARE SUPPORTED BY CURRENT
MOS NUMBERS.
VERY QUICK HITTING SHOT OF FAIRLY COLD AIR THEN ARRIVES LATER
THURSDAY NIGHT AND ESPECIALLY FRIDAY. THERE STILL DOES APPEAR TO BE
A SMALL WINDOW OF OPPORTUNITY FOR SOME LAKE EFFECT SNOW SHOWERS IN
PORTER COUNTY LATE THURSDAY NIGHT INTO FRIDAY MORNING...BUT NOT
EXPECTING ANYTHING SIGNIFICANT WITH LAKE EFFECT PARAMETERS FAIRLY
MARGINAL AND DURATION BEING SHORT AS FLOW QUICKLY BACKS TO
SOUTHERLY FRIDAY AFTERNOON.
BY THIS WEEKEND OUR ATTENTION WILL TURN THE THE VIGOROUS UPPER LOW
THATS CURRENTLY OFF THE BRITISH COLUMBIA COAST. MEDIUM RANGE
GUIDANCE IS IN REMARKABLY GOOD AGREEMENT THROUGH FRIDAY WITH THIS
SYSTEM DROPPING SOUTH AND WITH AN ANOMALOUSLY STRONG UPPER LOW (H5
HEIGHTS 3+ STANDARD DEVIATIONS BELOW AVERAGE) SETTING UP SHOP OVER
THE DESSERT SOUTHWEST BY FRIDAY. MODERATE RIDGING DOWNSTREAM OVER
THE SOUTHEASTERN CONUS SHOULD LEAVE OUR AREA IN A WEST-SOUTHWEST
FLOW ALOFT.
FORECAST CONFIDENCE THIS WEEKEND INTO EARLY NEXT WEEK IS LOW AS
MODELS OFTEN STRUGGLE WITH CUT OFF LOWS. HAVING SAID THAT...IT
APPEARS AS THOUGH THIS FIRST UPPER LOW WILL WEAKEN INTO AN OPEN WAVE
AND RIDE THE SOUTHWEST FLOW ALOFT INTO OUR AREA THIS WEEKEND...WITH
SOME DEGREE OF PHASING WITH A RESULTANT AMPLIFYING NORTHERN
STREAM TROUGH EXPECTED. WHILE DETAILS ARE MURKY...IT WOULD APPEAR
THAT OUR AREA IS IN STORE FOR INCREASINGLY UNSETTLED WEATHER LATE
SATURDAY INTO SUNDAY. WITH VARYING SOLUTIONS ABOUT THE TRACK OF
THE SURFACE SYSTEM AND RESULTANT THERMAL PROFILES IT WOULD BE
ABSURD TRYING TO PINPOINT P-TYPES FOR THE WEEKEND JUST YET.
ANOTHER...POTENTIALLY MORE SIGNIFICANT BUT BRIEF BLAST OF COLD AIR
LOOKS TO ARRIVE IN THE WAKE OF THIS SYSTEM EARLY NEXT WEEK.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* STRONG NORTH TO NORTHEAST WINDS WITH GUSTS TO 35 KT THROUGH
LATE THIS AFTERNOON.
* WINDS NOW BEGINNING A SLOW WEAKENING TREND.
* OCNL MVFR CIGS PERSISTING THROUGH SUNSET.
KREIN
//DISCUSSION...UPDATED 18Z...
WINDS WILL REMAIN THE MAIN AVIATION CONCERN THROUGH THIS EVENING.
THE STRONG LOW PRESSURE SYSTEM HAS MOVED INTO NORTHEASTERN OHIO.
COMBINED WITH HIGH PRESSURE EXTENDING FROM THE CENTRAL PLAINS
THROUGH THE WESTERN GREAT LAKE...THE SURFACE PRESSURE GRADIENT HAS
REACHED IT`S STRONGEST AND EXPECT A FAIRLY STEADY STATE TO WIND
SPEEDS FOR THE NEXT 4-5HRS. THE LATEST AIRCRAFT WIND REPORTS
INDICATE WIND SPEEDS AROUND 50KT AT THE TOP OF THE MIXED LAYER OF
ABOUT 4KFT AGL. HOWEVER...WITH OVC MVFR CIGS...THE STRONGEST WINDS
HAVE NOT BEEN ABLE TO MIX DOWN TO THE SURFACE...THOUGH 40+ KT GUSTS
HAVE BEEN OBSERVED AT ORD/MDW/GYY. THERE IS STILL THE POTENTIAL
FOR AN ISOLD 45-50KT GUST AT ORD/MDW THROUGH ABOUT
21Z...ESPECIALLY IF SOME BREAKS IN THE OVERCAST CAN DEVELOP.
THE LOW CENTER WILL STEADILY TRACK TO THE NORTHEAST THROUGH THE
AFTERNOON AND EVENING. WINDS WILL REMAIN STRONG AND GUSTY THROUGH
THE EVENING...AND EXPECT THAT GUSTS IN EXCESS OF 30KT WILL
CONTINUE THROUGH THE EARLY EVENING AND THEN GRADUALLY DIMINISH
THROUGH THE NIGHT.
AS THE SFC HIGH GRADUALLY BUILDS EASTWARD...CIGS SHOULD ALSO
GRADUALLY IMPROVE...GOING VFR BY EARLY EVENING.
KREIN
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MODERATE-HIGH CONFIDENCE IN CIG TRENDS.
* HIGH CONFIDENCE IN WIND FORECAST.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
KREIN
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT...VFR.
* THURSDAY...VFR. CHC LGT SN WITH MVFR IN THE EVENING.
* FRIDAY...CHC SHSN IN THE MORNING.
* SATURDAY...SLT CHC OF RA/SN WITH MVFR POSSIBLE.
* SUNDAY...CHC RA/SN. MVFR POSSIBLE.
* MONDAY...VFR.
KJB
&&
.MARINE...
153 PM...LOW PRESSURE NEAR LAKE ERIE WILL CONTINUE TO LIFT
NORTHEAST TONIGHT AND INTO QUEBEC WEDNESDAY MORNING WHILE A LARGE
RIDGE OF HIGH PRESSURE EXTENDS FROM JAMES BAY SOUTHWEST INTO THE
CENTRAL PLAINS. THE GRADIENT BETWEEN THESE TWO FEATURES WILL
REMAIN STRONG BUT SLOWLY WEAKEN TONIGHT. SPEEDS/GUSTS PEAKED MID
MORNING AND EXPECT GALES IN THE 40-45 KT RANGE FOR MUCH OF THE
EVENING...BUT THREAT FOR STORM FORCE GUSTS TO 50 KT APPEARS TO
HAVE ENDED.
THE RIDGE NOTED ABOVE WILL SPLIT TONIGHT AS ONE AREA MOVES EAST
ACROSS NORTHERN QUEBEC AND THE SOUTHERN AREA DROPS SOUTH ACROSS THE
SOUTHERN PLAINS AND OHIO VALLEY WEDNESDAY. THE NORTHERN PORTION OF
THIS RIDGE WILL MOVE ACROSS LAKE MICHIGAN WEDNESDAY AFTERNOON WITH
WIND SPEEDS RAPIDLY DIMINISHING WEDNESDAY MORNING AND BECOMING
SOUTHWEST BY EVENING.
A WEAK LOW WILL DEVELOP OVER THE PLAINS WEDNESDAY NIGHT AND QUICKLY
MOVE ACROSS THE NORTHERN LAKES REGION THURSDAY AFTERNOON...
DRAGGING A COLD FRONT ACROSS THE LAKE THURSDAY NIGHT. THE GRADIENT
TIGHTENS BEHIND THIS FRONT AS STRONG HIGH PRESSURE BUILDS ACROSS
THE PLAINS. BUT IN ADDITION TO THE TIGHTENING GRADIENT...COLDER
AIR WILL ALSO BE SPREADING ACROSS THE REGION AND EXPECT NORTHERLY
WINDS GUSTING TO AT LEAST 30 KTS WITH THE POTENTIAL FOR SOME GUSTS
TO 35 KTS. THIS HIGH THEN QUICKLY MOVES EAST ON FRIDAY WITH
SOUTHERLY WINDS DEVELOPING OVER THE LAKE FRIDAY NIGHT AS LOW
PRESSURE LIFTS NORTH ACROSS CANADA. ANOTHER COLD FRONT THEN MOVES
ACROSS THE LAKES REGION SUNDAY. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ006-ILZ014 UNTIL 9 PM TUESDAY.
LAKESHORE FLOOD ADVISORY...ILZ006-ILZ014 UNTIL 10 AM
WEDNESDAY.
IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002 UNTIL 3 PM WEDNESDAY.
WIND ADVISORY...INZ001-INZ002 UNTIL 9 PM TUESDAY.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878 UNTIL 9 AM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
403 AM CST TUE NOV 29 2011
.DISCUSSION...
938 PM CST
THE GOING FORECAST FOR TONIGHT INTO TUESDAY GENERALLY REMAINS ON
TRACK. THE UPPER LOW OVER THE LOWER TO MIDDLE PORTION OF THE
MISSISSIPPI VALLEY IS LOOKING VERY IMPRESSIVE ON WATER VAPOR
IMAGERY TONIGHT...WITH A WELL-DEFINED CLOSED CIRCULATION AND MOIST
CONVEYOR BELT FROM THE EASTERN GULF AND WESTERN ATLANTIC COMING
INTO THE SYSTEM. THE UPPER AIR PROFILES THIS EVENING PAINTED THE
PICTURE WITH THE COLD CORE UPPER LOW /-10C AT 850MB OVER MI/ AND A
VERY WARM AND MOIST NOSE TO THE NORTH /OVER 0C TD AT 700MB IN OH/.
THE WOLCOTT INDIANA WIND PROFILER IS SHOWING INCREASINGLY
EASTERLY WINDS UP TO 600 MB INDICATIVE OF THE SYSTEM TROWAL
DEVELOPMENT. THIS TROWAL AND ASSOCIATED ISENTROPIC OMEGA FROM THE
EAST STILL LOOK TO POINT DIRECTLY INTO NORTHWEST IN AND EASTERN IL
LATE TONIGHT INTO TUESDAY. SO DO EXPECT TO SEE RADAR ECHOES
CONTINUE TO BLOSSOM OVER THAT AREA. THE 29.00 RUC AND NAM CONTINUE
TO TREND EAST WITH THE WESTERN EDGE OF THE RAIN SHIELD...KEEPING
THE TIGHT GRADIENT BETWEEN NOTHING AND APPRECIABLE RAIN ABOUT 50
MILES EAST OF INTERSTATE 55. WILL GO AHEAD AND EASE THE NORTHWEST
SIDE OF THE POPS IN THE FORECAST...BUT OTHERWISE TIMING AND
ORIENTATION LOOK GOOD. PRECIPITATION AMOUNTS IN THE FAR SOUTHEAST
BETWEEN 1.25 AND 2 INCHES ARE PROBABLE. SUCH PREDICTED RAINFALL
AMOUNTS HAVE CAUSED THE FORECAST FOR THE KANKAKEE RIVER AT SHELBY
TO NOW GO ABOVE FLOOD STAGE. OTHER THAN A RIVER FLOOD WARNING FOR
THAT...NO OTHER CHANGES ARE PLANNED TO GOING HEADLINES THIS
EVENING. THE TRANSITION TO A MIX OR ALL SNOW DUE TO DYNAMIC
COOLING LOOKS PROBABLE WHEN THE UPPER LOW/PV ANOMALY ARE AT ITS
CLOSEST POINT DURING THE MID-AFTERNOON TO EARLY EVENING. THE
WINDOW OF TIME FOR PRECIPITATION TO FALL AS SNOW LOOKS SOMEWHAT
SHORTER IN THE NEW GUIDANCE...ENDING AROUND 9 PM TUE NIGHT.
STILL...THAT 4 TO 6 HOUR WINDOW IS ENOUGH TIME GIVEN THE FORCING
FOR HEAVIER RATES TO CAUSE SOME IMPACTS AND POTENTIALLY RESULT IN
MINOR SNOWFALL ACCUMULATIONS IN NORTHWEST IN.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 10Z...
* MVFR CIGS PERSISTING THROUGH MID MORNING
* STRONG NORTH TO NORTHEAST WINDS TODAY WITH GUSTS OVER 35 KT
POSSIBLE
KJB
//DISCUSSION...UPDATED 06Z...
DEEPENING LOW PRESSURE SYSTEM ACROSS THE TENNESSEE VALLEY
CONTINUES TO LIFT TO THE NORTHEAST AND TOWARDS THE OHIO VALLEY
TONIGHT. LATEST FORECAST TRENDS ARE KEEPING THE WESTERN EDGE OF
THE PRECIPITATION SHIELD FARTHER EAST THAN ORIGINALLY ANTICIPATED.
LATEST GUIDANCE IS IN AGREEMENT...AND WILL TREND IN THAT DIRECTION
WITH THE 04Z TAF AMD PACKAGE. WILL REMOVE ALL OF THE PRECIP FROM
ORD...SHIFT LESS WITH MDW AND THE SAME FOR GYY. MVFR CIGS SHOULD
REMAIN THROUGH THE OVERNIGHT HOURS AND GRADUALLY LIFT INTO THE
LATE MORNING HOURS...THOUGH THE FORECAST COULD GET A LITTLE TRICKY
FOR MDW IF ANY PRECIP DOES WORK FAR ENOUGH ACROSS THE TERMINALS.
PRESSURE GRADIENT WILL CONTINUE TO TIGHTEN AND WINDS WILL
INCREASE THROUGH THE MORNING HOURS. NORTHERLY GUSTS WILL INCREASE
TO A SUSTAINED LOWER 20 KT READING WITH GUSTS PEAKING AOA 35 KT
INTO THE EARLY AFTERNOON HOURS.
SHEA
//ORD AND MDW CONFIDENCE...UPDATED 10Z...
* MODERATE CONFIDENCE IN CIG TREND
* HIGH CONFIDENCE IN WIND FORECAST
* MODERATE CONFIDENCE IN PRECIPITATION REMAINING SOUTH OF ORD
KJB
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
* WEDNESDAY...VFR.
* THURSDAY...VFR. CHC LGT SN IN THE EVENING.
* FRIDAY...CHC SHSN IN THE MORNING.
* SATURDAY...VFR.
* SUNDAY...CHC RA/SN. MVFR POSSIBLE.
SHEA
&&
.MARINE...
344 AM CST
...HIGH GALES ON CENTRAL AND SOUTHERN LAKE MICHIGAN TODAY...
.LOW PRESSURE OF OVER THE LOWER OHIO VALLEY EARLY THIS MORNING
WILL MOVE NE TO LAKE ERIE BY EVENING WHILE HIGH PRESSURE MOVES
E ACROSS THE PLAINS. THE VERY STRONG PRESSURE GRADIENT DEVELOPING
OVER THE WESTERN GREAT LAKES HAS RESULTED IN NORTHEAST TO NORTH
WINDS INCREASING SIGNIFICANTLY...AND THE WITH VE REACHING GALE TO
HIGH GALE FORCE LATER THIS MORNING. THE GALE FORCE WINDS WILL
PERSIST INTO TONIGHT UNTIL THE DEEPENING LOW MOVES FURTHER
NE INTO SOUTHERN QUEBEC. WINDS DIMINISH WED AS THE HIGH SHIFTS
EAST OVER THE WESTERN GREAT LAKES AND OHIO VALLEY.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ006-ILZ014 UNTIL 9 PM TUESDAY.
LAKESHORE FLOOD ADVISORY...ILZ006-ILZ014 UNTIL 10 AM WEDNESDAY.
FLOOD WATCH...ILZ033 UNTIL 9 PM TUESDAY.
IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9 PM
TUESDAY.
LAKESHORE FLOOD ADVISORY...INZ001-INZ002 UNTIL 3 PM WEDNESDAY.
WIND ADVISORY...INZ001-INZ002 UNTIL 9 PM TUESDAY.
WINTER WEATHER ADVISORY...INZ010-INZ011-INZ019...NOON TUESDAY TO
MIDNIGHT WEDNESDAY.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878 UNTIL 9 AM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
349 AM CST TUE NOV 29 2011
.DISCUSSION...
938 PM CST
THE GOING FORECAST FOR TONIGHT INTO TUESDAY GENERALLY REMAINS ON
TRACK. THE UPPER LOW OVER THE LOWER TO MIDDLE PORTION OF THE
MISSISSIPPI VALLEY IS LOOKING VERY IMPRESSIVE ON WATER VAPOR
IMAGERY TONIGHT...WITH A WELL-DEFINED CLOSED CIRCULATION AND MOIST
CONVEYOR BELT FROM THE EASTERN GULF AND WESTERN ATLANTIC COMING
INTO THE SYSTEM. THE UPPER AIR PROFILES THIS EVENING PAINTED THE
PICTURE WITH THE COLD CORE UPPER LOW /-10C AT 850MB OVER MI/ AND A
VERY WARM AND MOIST NOSE TO THE NORTH /OVER 0C TD AT 700MB IN OH/.
THE WOLCOTT INDIANA WIND PROFILER IS SHOWING INCREASINGLY
EASTERLY WINDS UP TO 600 MB INDICATIVE OF THE SYSTEM TROWAL
DEVELOPMENT. THIS TROWAL AND ASSOCIATED ISENTROPIC OMEGA FROM THE
EAST STILL LOOK TO POINT DIRECTLY INTO NORTHWEST IN AND EASTERN IL
LATE TONIGHT INTO TUESDAY. SO DO EXPECT TO SEE RADAR ECHOES
CONTINUE TO BLOSSOM OVER THAT AREA. THE 29.00 RUC AND NAM CONTINUE
TO TREND EAST WITH THE WESTERN EDGE OF THE RAIN SHIELD...KEEPING
THE TIGHT GRADIENT BETWEEN NOTHING AND APPRECIABLE RAIN ABOUT 50
MILES EAST OF INTERSTATE 55. WILL GO AHEAD AND EASE THE NORTHWEST
SIDE OF THE POPS IN THE FORECAST...BUT OTHERWISE TIMING AND
ORIENTATION LOOK GOOD. PRECIPITATION AMOUNTS IN THE FAR SOUTHEAST
BETWEEN 1.25 AND 2 INCHES ARE PROBABLE. SUCH PREDICTED RAINFALL
AMOUNTS HAVE CAUSED THE FORECAST FOR THE KANKAKEE RIVER AT SHELBY
TO NOW GO ABOVE FLOOD STAGE. OTHER THAN A RIVER FLOOD WARNING FOR
THAT...NO OTHER CHANGES ARE PLANNED TO GOING HEADLINES THIS
EVENING. THE TRANSITION TO A MIX OR ALL SNOW DUE TO DYNAMIC
COOLING LOOKS PROBABLE WHEN THE UPPER LOW/PV ANOMALY ARE AT ITS
CLOSEST POINT DURING THE MID-AFTERNOON TO EARLY EVENING. THE
WINDOW OF TIME FOR PRECIPITATION TO FALL AS SNOW LOOKS SOMEWHAT
SHORTER IN THE NEW GUIDANCE...ENDING AROUND 9 PM TUE NIGHT.
STILL...THAT 4 TO 6 HOUR WINDOW IS ENOUGH TIME GIVEN THE FORCING
FOR HEAVIER RATES TO CAUSE SOME IMPACTS AND POTENTIALLY RESULT IN
MINOR SNOWFALL ACCUMULATIONS IN NORTHWEST IN.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 08Z...
* MVFR CIGS PERSISTING THROUGH MID MORNING
* STRONG NORTH TO NORTHEAST WINDS TODAY WITH GUSTS OVER 35 KT
POSSIBLE
KJB
//DISCUSSION...UPDATED 06Z...
DEEPENING LOW PRESSURE SYSTEM ACROSS THE TENNESSEE VALLEY
CONTINUES TO LIFT TO THE NORTHEAST AND TOWARDS THE OHIO VALLEY
TONIGHT. LATEST FORECAST TRENDS ARE KEEPING THE WESTERN EDGE OF
THE PRECIPITATION SHIELD FARTHER EAST THAN ORIGINALLY ANTICIPATED.
LATEST GUIDANCE IS IN AGREEMENT...AND WILL TREND IN THAT DIRECTION
WITH THE 04Z TAF AMD PACKAGE. WILL REMOVE ALL OF THE PRECIP FROM
ORD...SHIFT LESS WITH MDW AND THE SAME FOR GYY. MVFR CIGS SHOULD
REMAIN THROUGH THE OVERNIGHT HOURS AND GRADUALLY LIFT INTO THE
LATE MORNING HOURS...THOUGH THE FORECAST COULD GET A LITTLE TRICKY
FOR MDW IF ANY PRECIP DOES WORK FAR ENOUGH ACROSS THE TERMINALS.
PRESSURE GRADIENT WILL CONTINUE TO TIGHTEN AND WINDS WILL
INCREASE THROUGH THE MORNING HOURS. NORTHERLY GUSTS WILL INCREASE
TO A SUSTAINED LOWER 20 KT READING WITH GUSTS PEAKING AOA 35 KT
INTO THE EARLY AFTERNOON HOURS.
SHEA
//ORD AND MDW CONFIDENCE...UPDATED 08Z...
* MODERATE CONFIDENCE IN CIG TREND
* HIGH CONFIDENCE IN WIND FORECAST
* MODERATE CONFIDENCE IN PRECIPITATION REMAINING SOUTH OF ORD
KJB
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
* WEDNESDAY...VFR.
* THURSDAY...VFR. CHC LGT SN IN THE EVENING.
* FRIDAY...CHC SHSN IN THE MORNING.
* SATURDAY...VFR.
* SUNDAY...CHC RA/SN. MVFR POSSIBLE.
SHEA
&&
.MARINE...
344 AM CST
...HIGH GALES ON CENTRAL AND SOUTHERN LAKE MICHIGAN TODAY...
.LOW PRESSURE OF OVER THE LOWER OHIO VALLEY EARLY THIS MORNING
WILL MOVE NE TO LAKE ERIE BY EVENING WHILE HIGH PRESSURE MOVES
E ACROSS THE PLAINS. THE VERY STRONG PRESSURE GRADIENT DEVELOPING
OVER THE WESTERN GREAT LAKES HAS RESULTED IN NORTHEAST TO NORTH
WINDS INCREASING SIGNIFICANTLY...AND THE WITH VE REACHING GALE TO
HIGH GALE FORCE LATER THIS MORNING. THE GALE FORCE WINDS WILL
PERSIST INTO TONIGHT UNTIL THE DEEPENING LOW MOVES FURTHER
NE INTO SOUTHERN QUEBEC. WINDS DIMINISH WED AS THE HIGH SHIFTS
EAST OVER THE WESTERN GREAT LAKES AND OHIO VALLEY.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ006-ILZ014 UNTIL 9 PM TUESDAY.
LAKESHORE FLOOD ADVISORY...ILZ006-ILZ014 UNTIL 10 AM WEDNESDAY.
FLOOD WATCH...ILZ033 UNTIL 9 PM TUESDAY.
IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9 PM
TUESDAY.
LAKESHORE FLOOD ADVISORY...INZ001-INZ002 UNTIL 3 PM WEDNESDAY.
WIND ADVISORY...INZ001-INZ002 UNTIL 9 PM TUESDAY.
WINTER WEATHER ADVISORY...INZ010-INZ011-INZ019...NOON TUESDAY TO
MIDNIGHT WEDNESDAY.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878 UNTIL 9 AM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
211 AM CST TUE NOV 29 2011
.DISCUSSION...
938 PM CST
THE GOING FORECAST FOR TONIGHT INTO TUESDAY GENERALLY REMAINS ON
TRACK. THE UPPER LOW OVER THE LOWER TO MIDDLE PORTION OF THE
MISSISSIPPI VALLEY IS LOOKING VERY IMPRESSIVE ON WATER VAPOR
IMAGERY TONIGHT...WITH A WELL-DEFINED CLOSED CIRCULATION AND MOIST
CONVEYOR BELT FROM THE EASTERN GULF AND WESTERN ATLANTIC COMING
INTO THE SYSTEM. THE UPPER AIR PROFILES THIS EVENING PAINTED THE
PICTURE WITH THE COLD CORE UPPER LOW /-10C AT 850MB OVER MI/ AND A
VERY WARM AND MOIST NOSE TO THE NORTH /OVER 0C TD AT 700MB IN OH/.
THE WOLCOTT INDIANA WIND PROFILER IS SHOWING INCREASINGLY
EASTERLY WINDS UP TO 600 MB INDICATIVE OF THE SYSTEM TROWAL
DEVELOPMENT. THIS TROWAL AND ASSOCIATED ISENTROPIC OMEGA FROM THE
EAST STILL LOOK TO POINT DIRECTLY INTO NORTHWEST IN AND EASTERN IL
LATE TONIGHT INTO TUESDAY. SO DO EXPECT TO SEE RADAR ECHOES
CONTINUE TO BLOSSOM OVER THAT AREA. THE 29.00 RUC AND NAM CONTINUE
TO TREND EAST WITH THE WESTERN EDGE OF THE RAIN SHIELD...KEEPING
THE TIGHT GRADIENT BETWEEN NOTHING AND APPRECIABLE RAIN ABOUT 50
MILES EAST OF INTERSTATE 55. WILL GO AHEAD AND EASE THE NORTHWEST
SIDE OF THE POPS IN THE FORECAST...BUT OTHERWISE TIMING AND
ORIENTATION LOOK GOOD. PRECIPITATION AMOUNTS IN THE FAR SOUTHEAST
BETWEEN 1.25 AND 2 INCHES ARE PROBABLE. SUCH PREDICTED RAINFALL
AMOUNTS HAVE CAUSED THE FORECAST FOR THE KANKAKEE RIVER AT SHELBY
TO NOW GO ABOVE FLOOD STAGE. OTHER THAN A RIVER FLOOD WARNING FOR
THAT...NO OTHER CHANGES ARE PLANNED TO GOING HEADLINES THIS
EVENING. THE TRANSITION TO A MIX OR ALL SNOW DUE TO DYNAMIC
COOLING LOOKS PROBABLE WHEN THE UPPER LOW/PV ANOMALY ARE AT ITS
CLOSEST POINT DURING THE MID-AFTERNOON TO EARLY EVENING. THE
WINDOW OF TIME FOR PRECIPITATION TO FALL AS SNOW LOOKS SOMEWHAT
SHORTER IN THE NEW GUIDANCE...ENDING AROUND 9 PM TUE NIGHT.
STILL...THAT 4 TO 6 HOUR WINDOW IS ENOUGH TIME GIVEN THE FORCING
FOR HEAVIER RATES TO CAUSE SOME IMPACTS AND POTENTIALLY RESULT IN
MINOR SNOWFALL ACCUMULATIONS IN NORTHWEST IN.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 08Z...
* MVFR CIGS PERSISTING THROUGH MID MORNING
* STRONG NORTH TO NORTHEAST WINDS TODAY WITH GUSTS OVER 35 KT
POSSIBLE
KJB
//DISCUSSION...UPDATED 06Z...
DEEPENING LOW PRESSURE SYSTEM ACROSS THE TENNESSEE VALLEY
CONTINUES TO LIFT TO THE NORTHEAST AND TOWARDS THE OHIO VALLEY
TONIGHT. LATEST FORECAST TRENDS ARE KEEPING THE WESTERN EDGE OF
THE PRECIPITATION SHIELD FARTHER EAST THAN ORIGINALLY ANTICIPATED.
LATEST GUIDANCE IS IN AGREEMENT...AND WILL TREND IN THAT DIRECTION
WITH THE 04Z TAF AMD PACKAGE. WILL REMOVE ALL OF THE PRECIP FROM
ORD...SHIFT LESS WITH MDW AND THE SAME FOR GYY. MVFR CIGS SHOULD
REMAIN THROUGH THE OVERNIGHT HOURS AND GRADUALLY LIFT INTO THE
LATE MORNING HOURS...THOUGH THE FORECAST COULD GET A LITTLE TRICKY
FOR MDW IF ANY PRECIP DOES WORK FAR ENOUGH ACROSS THE TERMINALS.
PRESSURE GRADIENT WILL CONTINUE TO TIGHTEN AND WINDS WILL
INCREASE THROUGH THE MORNING HOURS. NORTHERLY GUSTS WILL INCREASE
TO A SUSTAINED LOWER 20 KT READING WITH GUSTS PEAKING AOA 35 KT
INTO THE EARLY AFTERNOON HOURS.
SHEA
//ORD AND MDW CONFIDENCE...UPDATED 08Z...
* MODERATE CONFIDENCE IN CIG TREND
* HIGH CONFIDENCE IN WIND FORECAST
* MODERATE CONFIDENCE IN PRECIPITATION REMAINING SOUTH OF ORD
KJB
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
* WEDNESDAY...VFR.
* THURSDAY...VFR. CHC LGT SN IN THE EVENING.
* FRIDAY...CHC SHSN IN THE MORNING.
* SATURDAY...VFR.
* SUNDAY...CHC RA/SN. MVFR POSSIBLE.
SHEA
&&
.MARINE...
255 PM CST
A SURFACE RIDGE AXIS EXTENDS ACROSS THE MIDDLE OF LAKE MICHIGAN
WITH SOUTHWEST WINDS OVER THE NORTHERN PORTIONS OF THE LAKE AND
NORTHEAST WINDS OVER THE SOUTH. DEEPENING LOW PRESSURE OVER
EASTERN TENNESSEE AND KENTUCKY WILL TRACK NORTHWARD THIS
EVENING...FORCING THE RIDGE AXIS TO THE NORTH AND STRENGTHENING
THE PRESSURE GRADIENT OVER LAKE MICHIGAN. WINDS WILL QUICKLY
STRENGTHEN THROUGH THE EVENING AND OVERNIGHT WILL GALE FORCE WINDS
DEVELOPING BY THE EARLY MORNING HOURS. GALES SHOULD INITIALLY DEVELOP
OVER THE FAR SOUTHERN PORTIONS OF THE LAKE...INCLUDING THE
NEARSHORE AND OFFSHORE WATERS...BUT THE GALES SHOULD RAPIDLY
SPREAD NORTH...ENGULFING ALL OF THE LAKE BY DAYBREAK. HIGHER END
GALES SHOULD DEVELOP BY MIDDAY AS THE SFC LOW MOVES OVER THE
EASTERN GREAT LAKES...WITH OCCASIONAL STORM FORCE GUSTS TO 50KT
POSSIBLE OVER THE SOUTHERN 2/3RDS OF THE LAKE. GALES SHOULD BEGIN
TO WIND DOWN WEDNESDAY MORNING AS THE SURFACE LOW MOVES INTO
QUEBEC AND A WEAK RIDGE CROSSES THE UPPER MISSISSIPPI VALLEY AND
INTO THE WESTERN GREAT LAKES REGION.
WHILE THE GALES SHOULD SUBSIDE WEDNESDAY MORNING...HIGH WAVES
HAZARDOUS TO SMALL CRAFT WILL LIKELY PERSIST THROUGH WEDNESDAY
NIGHT.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ006-ILZ014...6 AM TUESDAY TO 9 PM TUESDAY.
LAKESHORE FLOOD ADVISORY...ILZ006-ILZ014...6 AM TUESDAY TO 10 AM
WEDNESDAY.
FLOOD WATCH...ILZ033 UNTIL 9 PM TUESDAY.
IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9 PM
TUESDAY.
LAKESHORE FLOOD ADVISORY...INZ001-INZ002...6 AM TUESDAY TO 3 PM
WEDNESDAY.
WIND ADVISORY...INZ001-INZ002...6 AM TUESDAY TO 9 PM TUESDAY.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878 UNTIL 9 AM WEDNESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 3 AM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1052 PM CST MON NOV 28 2011
.DISCUSSION...
938 PM CST
THE GOING FORECAST FOR TONIGHT INTO TUESDAY GENERALLY REMAINS ON
TRACK. THE UPPER LOW OVER THE LOWER TO MIDDLE PORTION OF THE
MISSISSIPPI VALLEY IS LOOKING VERY IMPRESSIVE ON WATER VAPOR
IMAGERY TONIGHT...WITH A WELL-DEFINED CLOSED CIRCULATION AND MOIST
CONVEYOR BELT FROM THE EASTERN GULF AND WESTERN ATLANTIC COMING
INTO THE SYSTEM. THE UPPER AIR PROFILES THIS EVENING PAINTED THE
PICTURE WITH THE COLD CORE UPPER LOW /-10C AT 850MB OVER MI/ AND A
VERY WARM AND MOIST NOSE TO THE NORTH /OVER 0C TD AT 700MB IN OH/.
THE WOLCOTT INDIANA WIND PROFILER IS SHOWING INCREASINGLY
EASTERLY WINDS UP TO 600 MB INDICATIVE OF THE SYSTEM TROWAL
DEVELOPMENT. THIS TROWAL AND ASSOCIATED ISENTROPIC OMEGA FROM THE
EAST STILL LOOK TO POINT DIRECTLY INTO NORTHWEST IN AND EASTERN IL
LATE TONIGHT INTO TUESDAY. SO DO EXPECT TO SEE RADAR ECHOES
CONTINUE TO BLOSSOM OVER THAT AREA. THE 29.00 RUC AND NAM CONTINUE
TO TREND EAST WITH THE WESTERN EDGE OF THE RAIN SHIELD...KEEPING
THE TIGHT GRADIENT BETWEEN NOTHING AND APPRECIABLE RAIN ABOUT 50
MILES EAST OF INTERSTATE 55. WILL GO AHEAD AND EASE THE NORTHWEST
SIDE OF THE POPS IN THE FORECAST...BUT OTHERWISE TIMING AND
ORIENTATION LOOK GOOD. PRECIPITATION AMOUNTS IN THE FAR SOUTHEAST
BETWEEN 1.25 AND 2 INCHES ARE PROBABLE. SUCH PREDICTED RAINFALL
AMOUNTS HAVE CAUSED THE FORECAST FOR THE KANKAKEE RIVER AT SHELBY
TO NOW GO ABOVE FLOOD STAGE. OTHER THAN A RIVER FLOOD WARNING FOR
THAT...NO OTHER CHANGES ARE PLANNED TO GOING HEADLINES THIS
EVENING. THE TRANSITION TO A MIX OR ALL SNOW DUE TO DYNAMIC
COOLING LOOKS PROBABLE WHEN THE UPPER LOW/PV ANOMALY ARE AT ITS
CLOSEST POINT DURING THE MID-AFTERNOON TO EARLY EVENING. THE
WINDOW OF TIME FOR PRECIPITATION TO FALL AS SNOW LOOKS SOMEWHAT
SHORTER IN THE NEW GUIDANCE...ENDING AROUND 9 PM TUE NIGHT.
STILL...THAT 4 TO 6 HOUR WINDOW IS ENOUGH TIME GIVEN THE FORCING
FOR HEAVIER RATES TO CAUSE SOME IMPACTS AND POTENTIALLY RESULT IN
MINOR SNOWFALL ACCUMULATIONS IN NORTHWEST IN.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* MVFR CIGS PERSISTING THROUGH THE EVENING
* NORTHEAST WIND INCREASING OVERNIGHT...WITH STRONG GUSTS TOMORROW
* RAIN DEVELOPING TONIGHT MAINLY SOUTHEAST OF ORD
SHEA
//DISCUSSION...UPDATED 06Z...
DEEPENING LOW PRESSURE SYSTEM ACROSS THE TENNESSEE VALLEY
CONTINUES TO LIFT TO THE NORTHEAST AND TOWARDS THE OHIO VALLEY
TONIGHT. LATEST FORECAST TRENDS ARE KEEPING THE WESTERN EDGE OF
THE PRECIPITATION SHIELD FARTHER EAST THAN ORIGINALLY ANTICIPATED.
LATEST GUIDANCE IS IN AGREEMENT...AND WILL TREND IN THAT DIRECTION
WITH THE 04Z TAF AMD PACAKGE. WILL REMOVE ALL OF THE PRECIP FROM
ORD...SHIFT LESS WITH MDW AND THE SAME FOR GYY. MVFR CIGS SHOULD
REMAIN THROUGH THE OVERNIGHT HOURS AND GRADUALLY LIFT INTO THE
LATE MORNING HOURS...THOUGH THE FORECAST COULD GET A LITTLE TRICKY
FOR MDW IF ANY PRECIP DOES WORK FAR ENOUGH ACROSS THE TERMINALS.
PRESSURE GRADIENT WILL CONTINUE TO TIGHTEN AND WINDS WILL
INCREASE THROUGH THE MORNING HOURS. NORTERLY GUSTS WILL INCREASE
TO A SUSTAINED LOWER 20 KT READING WITH GUSTS PEAKING AOA 35 KT
INTO THE EARLY AFTERNOON HOURS.
SHEA
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MODERATE CONFIDENCE IN CIG TREND
* HIGH CONFIDENCE IN WIND FORECAST...MOD/HIGH IN GUST FORECAST
* MODERATE CONFIDENCE IN PRECIPITATION TIMING / COVERAGE LATE
TONIGHT INTO TUESDAY...STAYING EAST OR ORD
SHEA
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
* WEDNESDAY...VFR.
* THURSDAY...VFR. CHC LGT SN IN THE EVENING.
* FRIDAY...CHC SHSN IN THE MORNING.
* SATURDAY...VFR.
* SUNDAY...CHC RA/SN. MVFR POSSIBLE.
SHEA
&&
.MARINE...
255 PM CST
A SURFACE RIDGE AXIS EXTENDS ACROSS THE MIDDLE OF LAKE MICHIGAN
WITH SOUTHWEST WINDS OVER THE NORTHERN PORTIONS OF THE LAKE AND
NORTHEAST WINDS OVER THE SOUTH. DEEPENING LOW PRESSURE OVER
EASTERN TENNESSEE AND KENTUCKY WILL TRACK NORTHWARD THIS
EVENING...FORCING THE RIDGE AXIS TO THE NORTH AND STRENGTHENING
THE PRESSURE GRADIENT OVER LAKE MICHIGAN. WINDS WILL QUICKLY
STRENGTHEN THROUGH THE EVENING AND OVERNIGHT WILL GALE FORCE WINDS
DEVELOPING BY THE EARLY MORNING HOURS. GALES SHOULD INITIALLY DEVELOP
OVER THE FAR SOUTHERN PORTIONS OF THE LAKE...INCLUDING THE
NEARSHORE AND OFFSHORE WATERS...BUT THE GALES SHOULD RAPIDLY
SPREAD NORTH...ENGULFING ALL OF THE LAKE BY DAYBREAK. HIGHER END
GALES SHOULD DEVELOP BY MIDDAY AS THE SFC LOW MOVES OVER THE
EASTERN GREAT LAKES...WITH OCCASIONAL STORM FORCE GUSTS TO 50KT
POSSIBLE OVER THE SOUTHERN 2/3RDS OF THE LAKE. GALES SHOULD BEGIN
TO WIND DOWN WEDNESDAY MORNING AS THE SURFACE LOW MOVES INTO
QUEBEC AND A WEAK RIDGE CROSSES THE UPPER MISSISSIPPI VALLEY AND
INTO THE WESTERN GREAT LAKES REGION.
WHILE THE GALES SHOULD SUBSIDE WEDNESDAY MORNING...HIGH WAVES
HAZARDOUS TO SMALL CRAFT WILL LIKELY PERSIST THROUGH WEDNESDAY
NIGHT.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ006-ILZ014...6 AM TUESDAY TO 9 PM TUESDAY.
LAKESHORE FLOOD ADVISORY...ILZ006-ILZ014...6 AM TUESDAY TO 10 AM
WEDNESDAY.
FLOOD WATCH...ILZ033 UNTIL 9 PM TUESDAY.
IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9 PM
TUESDAY.
LAKESHORE FLOOD ADVISORY...INZ001-INZ002...6 AM TUESDAY TO 3 PM
WEDNESDAY.
WIND ADVISORY...INZ001-INZ002...6 AM TUESDAY TO 9 PM TUESDAY.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878...3 AM TUESDAY TO 9 AM WEDNESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 3 AM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1012 PM CST MON NOV 28 2011
.DISCUSSION...
938 PM CST
THE GOING FORECAST FOR TONIGHT INTO TUESDAY GENERALLY REMAINS ON
TRACK. THE UPPER LOW OVER THE LOWER TO MIDDLE PORTION OF THE
MISSISSIPPI VALLEY IS LOOKING VERY IMPRESSIVE ON WATER VAPOR
IMAGERY TONIGHT...WITH A WELL-DEFINED CLOSED CIRCULATION AND MOIST
CONVEYOR BELT FROM THE EASTERN GULF AND WESTERN ATLANTIC COMING
INTO THE SYSTEM. THE UPPER AIR PROFILES THIS EVENING PAINTED THE
PICTURE WITH THE COLD CORE UPPER LOW /-10C AT 850MB OVER MI/ AND A
VERY WARM AND MOIST NOSE TO THE NORTH /OVER 0C TD AT 700MB IN OH/.
THE WOLCOTT INDIANA WIND PROFILER IS SHOWING INCREASINGLY
EASTERLY WINDS UP TO 600 MB INDICATIVE OF THE SYSTEM TROWAL
DEVELOPMENT. THIS TROWAL AND ASSOCIATED ISENTROPIC OMEGA FROM THE
EAST STILL LOOK TO POINT DIRECTLY INTO NORTHWEST IN AND EASTERN IL
LATE TONIGHT INTO TUESDAY. SO DO EXPECT TO SEE RADAR ECHOES
CONTINUE TO BLOSSOM OVER THAT AREA. THE 29.00 RUC AND NAM CONTINUE
TO TREND EAST WITH THE WESTERN EDGE OF THE RAIN SHIELD...KEEPING
THE TIGHT GRADIENT BETWEEN NOTHING AND APPRECIABLE RAIN ABOUT 50
MILES EAST OF INTERSTATE 55. WILL GO AHEAD AND EASE THE NORTHWEST
SIDE OF THE POPS IN THE FORECAST...BUT OTHERWISE TIMING AND
ORIENTATION LOOK GOOD. PRECIPITATION AMOUNTS IN THE FAR SOUTHEAST
BETWEEN 1.25 AND 2 INCHES ARE PROBABLE. SUCH PREDICTED RAINFALL
AMOUNTS HAVE CAUSED THE FORECAST FOR THE KANKAKEE RIVER AT SHELBY
TO NOW GO ABOVE FLOOD STAGE. OTHER THAN A RIVER FLOOD WARNING FOR
THAT...NO OTHER CHANGES ARE PLANNED TO GOING HEADLINES THIS
EVENING. THE TRANSITION TO A MIX OR ALL SNOW DUE TO DYNAMIC
COOLING LOOKS PROBABLE WHEN THE UPPER LOW/PV ANOMALY ARE AT ITS
CLOSEST POINT DURING THE MID-AFTERNOON TO EARLY EVENING. THE
WINDOW OF TIME FOR PRECIPITATION TO FALL AS SNOW LOOKS SOMEWHAT
SHORTER IN THE NEW GUIDANCE...ENDING AROUND 9 PM TUE NIGHT.
STILL...THAT 4 TO 6 HOUR WINDOW IS ENOUGH TIME GIVEN THE FORCING
FOR HEAVIER RATES TO CAUSE SOME IMPACTS AND POTENTIALLY RESULT IN
MINOR SNOWFALL ACCUMULATIONS IN NORTHWEST IN.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 04Z...
* MVFR CIGS PERSISTING THROUGH THE EVENING
* NORTHEAST WIND INCREASING OVERNIGHT...WITH STRONG GUSTS TOMORROW
* RAIN DEVELOPING TONIGHT MAINLY SOUTHEAST OF ORD
SHEA
//DISCUSSION...UPDATED 04Z...
LATEST FORECAST TRENDS ARE KEEPING THE WESTERN EDGE OF THE
PRECIPITATION SHIELD FARTHER EAST THAN ORIGINALLY ANTICIPATED.
LATEST GUIDANCE IS IN AGREEMENT...AND WILL TREND IN THAT DIRECTION
WITH THE 04Z TAF AMD PACAKGE. WILL REMOVE ALL OF THE PRECIP FROM
ORD...SHIFT LOWER WITH MDW AND THE SAME FOR GYY. OTHERWISE...GOING
WIND AND CIG FORECAST LOOKS TO REMAIN ON TRACK. MVFR CIGS SHOULD
REMAIN THROUGH THE OVERNIGHT HOURS AND GRADUALLY LIFT INTO THE
LATE MORNING HOURS. PRESSURE GRADIENT WILL CONTINUE TO TIGHTEN AND
WINDS WILL INCREASE THROUGH THE MORNING HOURS.
SHEA
//DISCUSSION...UPDATED 00Z...
DEEPENING LOW PRESSURE SYSTEM ACROSS THE TENNESSEE VALLEY WILL
CONTINUE TO LIFT NORTH AND INTO THE OHIO VALLEY THIS EVENING.
IMPACT TO THE TERMINALS WILL TAKE PLACE OVERNIGHT...WITH RAIN
BEGINNING TO OVERSPREAD GYY BEYOND 05Z TONIGHT...AND LATER MOVING
ACROSS MDW. ORD AND DPA ARE WILDCARDS AS TO HOW LIKELY IT WILL
RAIN LATE TONIGHT AND INTO TOMORROW MORNING...VS JUST BEING IN THE
VC TO THE SOUTH AND EAST. PRESENT THINKING IS THAT THERE SHOULD BE
A WELL DEFINED LINE BETWEEN PRECIP AND NO PRECIP...AND THAT ORD
MAY STAY ON THE NO PRECIP SIDE. CONDITIONS WILL BE WORSE FOR MDW
AND WORSE YET FOR GYY. THAT SAID...WINDS WILL PICK UP TOMORROW FOR
ALL OF THE TERMINALS AND INCREASE TO A SUSTAINED 20+ KT RANGE AND
GUST INTO THE MIDDLE 30 KT RANGE. CIG TRENDS MAY BE A LITTLE
TRICKY WHERE THERE IS NO PRECIP FALLING...AS A WELL MIXED BOUNDARY
LAYER SHOULD KEEP CIGS FROM COMPLETELY TANKING...BUT THEY WILL
EASILY FALL TO LOW END MVFR AND POTENTIALLY IFR FOR LOCATIONS THAT
SEE RAIN /E.G. MDW AND GYY/.
SHEA
//ORD AND MDW CONFIDENCE...UPDATED 02Z...
* MODERATE CONFIDENCE IN CIG TREND
* HIGH CONFIDENCE IN WIND FORECAST...MOD/HIGH IN GUST FORECAST
* LOW CONFIDENCE IN PRECIPITATION TIMING / COVERAGE LATE TONIGHT
INTO TUESDAY
SHEA
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
* WEDNESDAY...VFR.
* THURSDAY...VFR. CHC LGT SN IN THE EVENING.
* FRIDAY...CHC SHSN IN THE MORNING.
* SATURDAY...VFR.
* SUNDAY...CHC RA/SN. MVFR POSSIBLE.
SHEA
&&
.MARINE...
255 PM CST
A SURFACE RIDGE AXIS EXTENDS ACROSS THE MIDDLE OF LAKE MICHIGAN
WITH SOUTHWEST WINDS OVER THE NORTHERN PORTIONS OF THE LAKE AND
NORTHEAST WINDS OVER THE SOUTH. DEEPENING LOW PRESSURE OVER
EASTERN TENNESSEE AND KENTUCKY WILL TRACK NORTHWARD THIS
EVENING...FORCING THE RIDGE AXIS TO THE NORTH AND STRENGTHENING
THE PRESSURE GRADIENT OVER LAKE MICHIGAN. WINDS WILL QUICKLY
STRENGTHEN THROUGH THE EVENING AND OVERNIGHT WILL GALE FORCE WINDS
DEVELOPING BY THE EARLY MORNING HOURS. GALES SHOULD INITIALLY DEVELOP
OVER THE FAR SOUTHERN PORTIONS OF THE LAKE...INCLUDING THE
NEARSHORE AND OFFSHORE WATERS...BUT THE GALES SHOULD RAPIDLY
SPREAD NORTH...ENGULFING ALL OF THE LAKE BY DAYBREAK. HIGHER END
GALES SHOULD DEVELOP BY MIDDAY AS THE SFC LOW MOVES OVER THE
EASTERN GREAT LAKES...WITH OCCASIONAL STORM FORCE GUSTS TO 50KT
POSSIBLE OVER THE SOUTHERN 2/3RDS OF THE LAKE. GALES SHOULD BEGIN
TO WIND DOWN WEDNESDAY MORNING AS THE SURFACE LOW MOVES INTO
QUEBEC AND A WEAK RIDGE CROSSES THE UPPER MISSISSIPPI VALLEY AND
INTO THE WESTERN GREAT LAKES REGION.
WHILE THE GALES SHOULD SUBSIDE WEDNESDAY MORNING...HIGH WAVES
HAZARDOUS TO SMALL CRAFT WILL LIKELY PERSIST THROUGH WEDNESDAY
NIGHT.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ006-ILZ014...6 AM TUESDAY TO 9 PM TUESDAY.
LAKESHORE FLOOD ADVISORY...ILZ006-ILZ014...6 AM TUESDAY TO 10 AM
WEDNESDAY.
FLOOD WATCH...ILZ033 UNTIL 9 PM TUESDAY.
IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 9 PM
TUESDAY.
LAKESHORE FLOOD ADVISORY...INZ001-INZ002...6 AM TUESDAY TO 3 PM
WEDNESDAY.
WIND ADVISORY...INZ001-INZ002...6 AM TUESDAY TO 9 PM TUESDAY.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878...3 AM TUESDAY TO 9 AM WEDNESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 3 AM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
529 PM EST TUE NOV 29 2011
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
THE UPPER LOW WILL MOVE INTO THE NORTHEAST USA BY WEDNESDAY
MORNING...ENDING THE PRECIPITATION ACROSS THE AREA. A COLD FRONT
WILL MOVE INTO THE AREA FOR THE WEEKEND INTO EARLY NEXT WEEK
BRINGING ANOTHER CHANCE FOR PRECIPITATION.
&&
.NEAR TERM /REST OF THIS AFTERNOON AND TONIGHT/...
FOCUS IS ON SNOW EVENT. MODELS ARE SIMILAR ENOUGH THAT A BLEND CAN
BE USED.
THERMAL PROFILES HAVE COOLED ENOUGH THAT MOST OF THE PRECIPITATION
IS SNOW ACROSS THE FORECAST AREA AT 20Z. EXCEPTIONS ARE WHERE
PRECIPITATION IS LIGHTEST WHERE IT IS STILL RAIN. THUS EXPECT SNOW
AS THE MAIN PRECIPITATION TYPE FOR THE REST OF THE PERIOD.
HEAVIEST SNOW IS FALLING IN AREAS OF STRONGEST FRONTOGENETICAL
FORCING AT 850 AND 700 MB. LATEST RUC FORECAST IS FOR THESE
HEAVIER BANDS TO REMAIN RELATIVELY STATIONARY FOR THE NEXT FEW
HOURS BEFORE MOVING EAST THIS EVENING. THESE BANDS ARE MAINLY
WHERE THE WINTER WEATHER ADVISORY ALREADY EXISTS.
HOWEVER RECENT TRENDS ARE TO GO A LITTLE FARTHER SOUTH WITH THE
HEAVIER SNOW...SO WILL EXPAND THE ADVISORY ONE MORE TIER OF
COUNTIES SOUTH INTO INDIANAPOLIS PROPER....ESPECIALLY SINCE SNOW
WILL BE FALLING IN RUSH HOUR THERE.
BASED ON WHAT HAS ALREADY FALLEN...SOME MELTING...AND WHAT WILL
FALL THIS EVENING KEPT STORM TOTAL AMOUNTS NEAR 4 INCHES ACROSS
THE FAR NORTH TO 1 TO 2 INCHES ALONG I-70 AND LOWER AMOUNTS SOUTH.
FORCING QUICKLY EXITS THE AREA THIS EVENING SO WILL ONLY GO
CHANCE POPS AFTER 06Z.
MOS LOOKS TOO COLD WITH LOW TEMPERATURES GIVEN EXPECTED CLOUD
COVER...SO WENT CLOSER TO ENSEMBLE MEANS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
FOCUS IS ON SKY EARLY THEN ON TEMPERATURES. MODELS ARE SIMILAR SO
USED A BLEND.
FORCING WILL BE FAR ENOUGH EAST BY WEDNESDAY MORNING SO THAT CAN
GO DRY ALL AREAS. LOOKING AT LOW LEVEL RELATIVE HUMIDITY
FORECASTS....BELIEVE THAT LOW CLOUDS WILL HANG AROUND UNTIL MID
DAY...ESPECIALLY EAST. THESE WILL KEEP TEMPERATURES CLOSER TO THE
COOLER MAV MOS MOST AREAS.
HIGH PRESSURE WILL THEN PROVIDE DRY CONDITIONS INTO THURSDAY
NIGHT. MAV MOS LOOKS LIKE A COOL OUTLIER FOR LOWS WEDNESDAY NIGHT
SO WENT CLOSER TO THE MET AND ENSEMBLE MEANS. USED A BLEND OF MOS
FOR THURSDAY.
A FRONT WILL MOVE INTO THE AREA LATE THURSDAY NIGHT INTO
FRIDAY...BUT FORCING IS MINIMAL WITH IT AS BEST ENERGY REMAINS
WELL TO THE NORTH. ALSO MOISTURE IS WEAK AS WELL...SO WENT DRY ON
FRIDAY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
MAIN LONG TERM FOCUS WILL BE A DEEPENING UPPER TROUGH WHICH MOVES
FROM THE NORTHERN PLAINS SATURDAY TO THE GREAT LAKES BY MONDAY AND
EASTERN GREAT LAKES TO WEST VIRGINIA BY TUESDAY. MODELS ARE A
LITTLE MORE PROGRESSIVE THIS RUN...BUT STILL KEEP PRECIP JUST TO
OUR NORTHWEST SATURDAY. PRECIP WILL BEGIN MOST AREAS LATE SATURDAY
NIGHT AND MAINLY AS LIGHT RAIN. BUT I WOULD NOT RULE OUT A BRIEF
PERIOD OF SNOW IN OUR NORTH WHEN IT FIRST STARTS.
AS MENTIONED ABOVE MODELS HAVE TRENDED MORE PROGRESSIVE AND THE
TRAILING COLD FRONT SHOULD BE FAR ENOUGH EAST BY MONDAY FOR MOST
AREAS TO BE DRY BY THEN. SOME MODELS INCLUDING HPC INDICATE A WEAK
SECONDARY SYSTEM WILL MOVE ACROSS THE SOUTHERN GREAT LAKES MONDAY
NIGHT AND WILL ADD A SLIGHT CHANCE OF SNOW SHOWERS ACROSS OUR FAR
NORTH. OTHERWISE...DRY AND COLD WEATHER WILL BE THE RULE AFTER THIS
UPCOMING WEEKEND.
&&
.AVIATION /DISCUSSION FOR THE 300000Z TAFS/...
PRECIPITATION AREA HAS BEGUN TO SHRINK IN BOTH COVERAGE AND
INTENSITY OVER THE PAST HOUR OR SO AS LIFT WITHIN THE DEFORMATION
ZONE WEAKENS AND PUSHES OFF TO THE NORTHEAST. PRECIPITATION HAS
MAINLY BEEN A MIX OF RAIN/SNOW WITH THE SNOW LINKED TO THE STRONGER
RETURNS ON THE RADAR. THIS PROCESS EXPECTED TO CONTINUE THIS EVENING
AS DEFORMATION ZONE WEAKENS. APPEARS PRECIPITATION WILL BE OVER AT
KHUF/KLAF BY ISSUANCE TIME...AND BY 300200Z-300300Z AT KIND/KBMG.
PRECIPITATION MAY STILL BE HEAVY ENOUGH FOR IFR VISIBILITY
RESTRICTIONS AT KIND/KBMG UNTIL ABOUT 300100Z.
CEILINGS EXPECTED TO IMPROVE RATHER RAPIDLY LATER THIS EVENING AS
THE PRECIPITATION ENDS. ALREADY SEEING CEILINGS 030-040 OBSERVED
JUST ACROSS THE ILLINOIS STATE LINE. EXPECTING THE LINGERING IFR
CEILINGS TO LIFT INTO A 030-040 DECK BY 300300Z.
SURFACE WIND GUSTS UP TO ABOUT 25 KTS FROM 320-350 HEADINGS EXPECTED
THROUGHOUT MOST OF THE EVENING...WITH THESE GUSTS DIMINISHING AFTER
300600Z AS PRESSURE GRADIENT LOOSENS UP.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 1 AM EST WEDNESDAY FOR INZ021-
028>031-035>049.
&&
$$
SYNOPSIS...50/AH
NEAR TERM...50/AH
SHORT TERM...50/AH
LONG TERM....JH
AVIATION...JAS
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
403 PM EST TUE NOV 29 2011
.SHORT TERM.../TONIGHT/
...FIRST WIDESPREAD SNOW OF THE SEASON COMMENCING...
UPDATES ISSUED EARLIER GENERALLY ON TRACK WITH RAPID COOLING OF
COLUMN OCCURRING BETWEEN 18 AND 20Z. MANY LOCATIONS NOW REPORTING
SNOW OR A MIX OF SNOW/SLEET/RAIN. SNOW AMOUNTS INITIALLY MAY BE ON
LIGHTER SIDE WITH MELTING OCCURRING ON SLIGHTLY WARMER SURFACES.
HOWEVER AS UPPER LOW APPROACHES LATE THIS AFTERNOON AND EVENING AND
MESOBANDING BETTER ESTABLISHES SNOWFALL RATES SHOULD INCREASE ACROSS
MUCH OF THE WARNING AREA. SPORADIC LIGHTNING STRIKES SEEN SW OF THE
AREA IN MAIN MESOBAND WHICH WILL TRANSLATE THROUGH THE AREA INTO
TONIGHT.
HEAVIEST SNOWFALL WILL OCCUR BETWEEN 22Z TUES AND 6Z WEDS AS MAIN
DEFORMATION ZONE SHIFTS ACROSS THE FORECAST AREA. SEVERAL RUNS OF
THE HRRR HAVE SHOWN THE MAIN SWATH OF HEAVIER SNOW TO TAKE SHAPE
EITHER SIDE OF A MARION TO ANGOLA TO HILLSDALE LINE. THIS MODEL
DEPICTS UPWARDS OF 8 TO 12 INCHES OF SNOWFALL. THINK THIS IS LIKELY
OVER DONE WITH GREATER CONFIDENCE IN DECENT AREA OF 4 TO 7 INCHES OF
SNOW WITH AMOUNTS APPROACHING 8 ESPECIALLY ACROSS PORTIONS OF
NORTHEASTERN INDIANA INTO FAR SOUTHERN LWR MI AND FAR NW OHIO. WILL
LET EVE SHIFT MONITOR TRENDS OF AMOUNTS AND HEAVIEST BAND AND ADJUST
HEADLINES ACCORDINGLY. TEMPS WILL CONTINUE TO FALL AND BOTTOM OUT IN
THE UPPER 20S TO AROUND 30.
WINDS WILL ALSO INCREASE TONIGHT AS THE TIGHTLY WRAPPED LOW
CONTINUES TO MOVE AWAY. AS WE GET INTO THE OVERNIGHT HOURS THIS
COULD CAUSE SOME DRIFTING AND LOW BLOWING OF THE SNOW...BUT GIVEN
THE INITIAL WET CONTENT...NOT EXPECTED TO BE A SIG IMPACT.
&&
.LONG TERM...
MINOR ADJUSTMENTS TO THE TEMPERATURES WEDNESDAY AND WEDNESDAY NIGHT
TO TAKE INTO ACCOUNT OUR LATEST SNOWFALL FORECASTS AND EXPECTED
CLOUD COVER. HAVE NUDGED TEMPS DOWN FOR THE MAX T AND UP FROM
PREVIOUS GRIDS FOR OVERNIGHT LOW. WITH CYCLONIC FLOW OVER THE REGION
EXPECT THAT CLOUDS WILL PERSIST AND HAVE INCREASED CLOUD COVER - BUT
MAY NOT HAVE INCREASED ENOUGH FOR THURSDAY.
LONGWAVE PATTERN IS BEGINNING TO BE MUCH MORE AMPLIFIED AND THIS
SETS UP A PROGRESSIVE PATTERN OVER THE GREAT LAKES REGION BEGINNING
THURSDAY WITH ANOTHER VIGOROUS SHORTWAVE TO TO DIVE OUT OF THE
NORTHERN PLAINS BY SATURDAY...LEADING TO ANOTHER SHOT OF COLDER AIR
POISED TO DROP OUT OF THE CANADIAN PLAINS THIS COMING WEEKEND.
WITH A BRIEF WARMING TREND THU/FRI TEMPS WILL BE BELOW NORMAL
BEGINNING SAT-NEXT TUES.
WITH THE INCOMING SHORTWAVE ON SATURDAY...HAVE INCREASED POP TO MORE
CLOSELY MATCH SURROUNDING OFFICES AND WOULD EXPECT TO SEE ANOTHER
ACCUMULATING SNOWFALL DURING THE PERIOD.
&&
.AVIATION...
FLIGHT CONDITIONS WILL CONTINUE TO DETERIORATE ACROSS THE AREA
THIS AFTERNOON AND EVENING AS RAIN QUICKLY SWITCHES TO SNOW AND
BECOMES HEAVY AT TIMES. CIGS AND VSBY INTO THE IFR IF NOT LIFR
RANGE WILL OCCUR INTO THIS EVENING. PRECIP WILL BEGIN TO TAPER
AFTER 6Z BUT AT LEAST MVFR CIGS WILL PERSIST.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER STORM WARNING UNTIL 1 AM EST WEDNESDAY FOR INZ006>009-
015>018-022>027-032>034.
WINTER WEATHER ADVISORY UNTIL 1 AM EST /MIDNIGHT CST/ WEDNESDAY
FOR INZ004-005-012>014-020.
MI...WINTER STORM WARNING UNTIL 1 AM EST WEDNESDAY FOR MIZ080-081.
WINTER WEATHER ADVISORY UNTIL 1 AM EST WEDNESDAY FOR MIZ078-079.
OH...WINTER STORM WARNING UNTIL 1 AM EST WEDNESDAY FOR OHZ001-002-004-
015.
LM...GALE WARNING UNTIL 10 AM EST WEDNESDAY FOR LMZ043-046.
&&
$$
SHORT TERM...FISHER
LONG TERM...LEWIS
AVIATION...SKIPPER
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
330 PM EST TUE NOV 29 2011
.UPDATE...
THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN UPDATED BELOW
&&
.SYNOPSIS...
THE UPPER LOW WILL MOVE INTO THE NORTHEAST USA BY WEDNESDAY
MORNING...ENDING THE PRECIPITATION ACROSS THE AREA. A COLD FRONT
WILL MOVE INTO THE AREA FOR THE WEEKEND INTO EARLY NEXT WEEK
BRINGING ANOTHER CHANCE FOR PRECIPITATION.
&&
.NEAR TERM /REST OF THIS AFTERNOON AND TONIGHT/...
FOCUS IS ON SNOW EVENT. MODELS ARE SIMILAR ENOUGH THAT A BLEND CAN
BE USED.
THERMAL PROFILES HAVE COOLED ENOUGH THAT MOST OF THE PRECIPITATION
IS SNOW ACROSS THE FORECAST AREA AT 20Z. EXCEPTIONS ARE WHERE
PRECIPITATION IS LIGHTEST WHERE IT IS STILL RAIN. THUS EXPECT SNOW
AS THE MAIN PRECIPITATION TYPE FOR THE REST OF THE PERIOD.
HEAVIEST SNOW IS FALLING IN AREAS OF STRONGEST FRONTOGENETICAL
FORCING AT 850 AND 700 MB. LATEST RUC FORECAST IS FOR THESE
HEAVIER BANDS TO REMAIN RELATIVELY STATIONARY FOR THE NEXT FEW
HOURS BEFORE MOVING EAST THIS EVENING. THESE BANDS ARE MAINLY
WHERE THE WINTER WEATHER ADVISORY ALREADY EXISTS.
HOWEVER RECENT TRENDS ARE TO GO A LITTLE FARTHER SOUTH WITH THE
HEAVIER SNOW...SO WILL EXPAND THE ADVISORY ONE MORE TIER OF
COUNTIES SOUTH INTO INDIANAPOLIS PROPER....ESPECIALLY SINCE SNOW
WILL BE FALLING IN RUSH HOUR THERE.
BASED ON WHAT HAS ALREADY FALLEN...SOME MELTING...AND WHAT WILL
FALL THIS EVENING KEPT STORM TOTAL AMOUNTS NEAR 4 INCHES ACROSS
THE FAR NORTH TO 1 TO 2 INCHES ALONG I-70 AND LOWER AMOUNTS SOUTH.
FORCING QUICKLY EXITS THE AREA THIS EVENING SO WILL ONLY GO
CHANCE POPS AFTER 06Z.
MOS LOOKS TOO COLD WITH LOW TEMPERATURES GIVEN EXPECTED CLOUD
COVER...SO WENT CLOSER TO ENSEMBLE MEANS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
FOCUS IS ON SKY EARLY THEN ON TEMPERATURES. MODELS ARE SIMILAR SO
USED A BLEND.
FORCING WILL BE FAR ENOUGH EAST BY WEDNESDAY MORNING SO THAT CAN
GO DRY ALL AREAS. LOOKING AT LOW LEVEL RELATIVE HUMIDITY
FORECASTS....BELIEVE THAT LOW CLOUDS WILL HANG AROUND UNTIL MID
DAY...ESPECIALLY EAST. THESE WILL KEEP TEMPERATURES CLOSER TO THE
COOLER MAV MOS MOST AREAS.
HIGH PRESSURE WILL THEN PROVIDE DRY CONDITIONS INTO THURSDAY
NIGHT. MAV MOS LOOKS LIKE A COOL OUTLIER FOR LOWS WEDNESDAY NIGHT
SO WENT CLOSER TO THE MET AND ENSEMBLE MEANS. USED A BLEND OF MOS
FOR THURSDAY.
A FRONT WILL MOVE INTO THE AREA LATE THURSDAY NIGHT INTO
FRIDAY...BUT FORCING IS MINIMAL WITH IT AS BEST ENERGY REMAINS
WELL TO THE NORTH. ALSO MOISTURE IS WEAK AS WELL...SO WENT DRY ON
FRIDAY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
MAIN LONG TERM FOCUS WILL BE A DEEPENING UPPER TROUGH WHICH MOVES
FROM THE NORTHERN PLAINS SATURDAY TO THE GREAT LAKES BY MONDAY AND
EASTERN GREAT LAKES TO WEST VIRGINIA BY TUESDAY. MODELS ARE A
LITTLE MORE PROGRESSIVE THIS RUN...BUT STILL KEEP PRECIP JUST TO
OUR NORTHWEST SATURDAY. PRECIP WILL BEGIN MOST AREAS LATE SATURDAY
NIGHT AND MAINLY AS LIGHT RAIN. BUT I WOULD NOT RULE OUT A BRIEF
PERIOD OF SNOW IN OUR NORTH WHEN IT FIRST STARTS.
AS MENTIONED ABOVE MODELS HAVE TRENDED MORE PROGRESSIVE AND THE
TRAILING COLD FRONT SHOULD BE FAR ENOUGH EAST BY MONDAY FOR MOST
AREAS TO BE DRY BY THEN. SOME MODELS INCLUDING HPC INDICATE A WEAK
SECONDARY SYSTEM WILL MOVE ACROSS THE SOUTHERN GREAT LAKES MONDAY
NIGHT AND WILL ADD A SLIGHT CHANCE OF SNOW SHOWERS ACROSS OUR FAR
NORTH. OTHERWISE...DRY AND COLD WEATHER WILL BE THE RULE AFTER THIS
UPCOMING WEEKEND.
&&
.AVIATION /DISCUSSION FOR 29/18Z TAF ISSUANCE/...
VERY POOR FLYING CONDITIONS WILL CONTINUE INTO THIS EVENING AND
IMPROVE OVERNIGHT AND EARLY WEDNESDAY TO VFR. STRONG LOW PRESSURE
OVER NORTHERN OHIO WILL CONTINUE MOVING NORTHEAST ACROSS THE EASTERN
GREAT LAKES INTO SOUTHEAST CANADA. AS COLDER AIR WRAPS INTO OUR
REGION...A MIXTURE OF RAIN AND SOME SLEET WILL CHANGE TO ALL SNOW BY
MID OR LATE AFTERNOON. PRECIPITATION WILL BEGIN DIMINISHING WEST TO
EAST THIS EVENING AND WILL END ALL AREAS BY 06Z LEAVING MVFR
CEILINGS OVERNIGHT.
DRIER AIR WILL GRADUALLY MOVE IN LATE TONIGHT AND WEDNESDAY
IMPROVING CONDITIONS TO VFR OVER WESTERN SECTIONS LATE TONIGHT AND
EVEN INDY BY 13Z WEDNESDAY. CLEAR SKIES ARE POSSIBLE SOME AREAS BY
END OF THE TAF PERIOD.
A STRONG PRESSURE GRADIENT WILL CAUSE WINDS TO BECOME NORTHWEST 15
KNOTS WITH GUSTS TO 25 KNOTS BY LATE AFTERNOON. WINDS WILL GRADUALLY
DIMINISH OVERNIGHT AND WEST TO NORTHWEST WINDS OF 10 KNOTS OR LESS
WILL BE THE RULE WEDNESDAY.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 1 AM EST WEDNESDAY FOR INZ021-
028>031-035>049.
&&
$$
SYNOPSIS...50/AH
NEAR TERM...50/AH
SHORT TERM...50/AH
LONG TERM....JH
AVIATION...JH
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
125 PM EST TUE NOV 29 2011
.UPDATE...
ZONES/GRIDS WERE UPDATED EARLIER TO UPGRADE PORTIONS OF THE WATCH
TO A WARNING WITH REMAINING COUNTIES UNDER AN ADVISORY.
AREA IN INCREASED ASCENT AND LOCALIZED WAA HAS OCCURRED ACROSS
PORTIONS OF NW OHIO SW INTO WESTERN INDIANA BY LAFAYETTE. RAIN HAS
BEEN MIXING AT TIMES WITH SLEET AS COLDER AIR CONTINUES TO
STRUGGLE WITH SHALLOW WAA IN LOWER LEVELS. AS DYNAMIC COOLING
COMMENCES SLEET WILL BECOME MORE PREDOMINATE AND THEN SWITCH TO
SNOW. SWOMCD ISSUED RECENTLY HIGHLIGHTING INCREASING CONCERN FOR
HEAVY SNOW ACROSS MUCH OF THE FORECAST AREA...ESPECIALLY IN NE
INDIANA AND NW OHIO WITH ONE INCH OR MORE PER HOUR RATES POSSIBLE.
ADDITIONAL MESOSCALE DETAILS CAN BE FOUND IN THIS PRODUCT. THE BIG
CHALLENGE IS WHEN EXACTLY THE SWITCH OVER OCCURS AND HOW LONG THE
BAND PERSISTS ACROSS THE AREA AS THE UPPER LOW QUICKLY EXITS.
ALTHOUGH EXTREME AMOUNTS ARE NOT EXPECTED...GENERAL SWATH OF 4 TO
6 INCHES WITH LOCALLY HIGHER AMOUNTS LOOK TO OCCUR FROM EAST OF A
LOGANSPORT TO WARSAW TO COLDWATER LINE. ALTHOUGH GENERALLY UNDER
TYPICAL CRITERIA...TIMING OF HEAVIEST SNOW COINCIDING WITH
AFTERNOON/EVENING RUSH HOUR...COMBINED WITH FIRST WIDESPREAD
SNOWFALL...WARRANTED A BIT MORE AGGRESSIVE HANDLE ON HEADLINES. AS
A RESULT HAVE UPGRADED TO WARNING IN THESE AREA WITH EASTERN
FRINGE GOING JUST TO THE EAST OF I-69. FAR EASTERN PORTIONS OF THE
WARNING MAY SEE A BIT MORE SLEET THAN OTHERS BEING CLOSER TO
WARMEST AIR BUT STILL SHOULD SQUEEZE OUT ENOUGH SNOW TO BE OF
CONCERN. WEST OF THE ABOVE MENTIONED LINE...WINTER WEATHER
ADVISORY HAS BEEN ISSUED FOR THE TIME BEING WITH CONTINUED
MONITORING AS SNOW BAND UNFOLDS.
&&
.AVIATION...
FLIGHT CONDITIONS WILL CONTINUE TO DETERIORATE ACROSS THE AREA
THIS AFTERNOON AND EVENING AS RAIN QUICKLY SWITCHES TO SNOW AND
BECOMES HEAVY AT TIMES. CIGS AND VSBY INTO THE IFR IF NOT LIFR
RANGE WILL OCCUR INTO THIS EVENING. PRECIP WILL BEGIN TO TAPER
AFTER 6Z BUT AT LEAST MVFR CIGS WILL PERSIST.
&&
.PREV DISCUSSION... /ISSUED 1000 AM EST TUE NOV 29 2011/
HYDROLOGY...
HAVE UPDATED THE FLOOD WATCH TO AN AREAL FLOOD WARNING FOR THE
ENTIRE AREA. SATURATED GROUND FROM EARLIER RAINFALL HAS CAUSED
THE ADDITIONAL RAINFALL TO RUNOFF AND PRODUCE SOME FLOODING OF
ROADS AND RAPID RISES ON STREAMS. ADDITIONAL RAINFALL OF 1 TO
2 INCHES AND EVEN MELTED SNOW LATER TODAY IS EXPECTED TO CAUSE
WIDESPREAD AREAL FLOODING LATER TODAY.
PREV DISCUSSION... /ISSUED 446 AM EST TUE NOV 29 2011/
SHORT TERM...
DYNAMIC/IMPRESSIVE SRN STREAM WAVE CONTS TO WRAP UP ACRS WRN TN
EARLY THIS MORNING W/MATURE INTENSE TROWAL TO ITS NORTH. WIDESPREAD
MOD-HVY RAIN WAS ONGOING ACRS MUCH OF THE CWA W/HEAVIEST BANDED PCPN
ORIENTED SW-NE THROUGH ACRS THE NW HALF.
COMPLEX/MULTI-FACETED FCST GOING FWD FOR TDA AND TONIGHT. COLD CORE
LOW OVR WRN TN WILL LIFT OUT NEWD THROUGH WRN OH AND DEEPEN THROUGH LT
AFTN IN RESPONSE TO UPSTREAM NRN STREAM TROUGH MAKING QUICK EWD
PROGRESS ACRS THE UPR MIDWEST. IN FACT FULL GAMUT OF 00Z GUIDANCE
TRENDED QUICKER W/RAIN-SNOW CHG OVR AND IN LIFTING THIS DEEP SYS OUT
W/VAPOR INDICATING FTR BEGINNING TO GET PICKED UP W/RAIN CHG TO SNOW
NOW INTO SE MO/SRN IL. HWVR MODEL INTRICACIES ABOUND ESP W/TIMING OF
CHG OVR AND PLACEMENT OF MOST INTENSE PORTION OF MID LVL DEFORMATION
BAND. EARLY CONJECTURE HERE GIVES A NOD TO MODELS THAT IMPLY A
FASTER CHG OVR/WWD PLACEMENT GIVEN NRN STREAM TROUGH IS SLIGHTLY EWD
OF PRIOR 03Z RUC GUIDANCE AND QUICKER W/INFILTRATION OF LL CAA WING
ADVTG SWWD WITHIN RAPIDLY INCREASING LL AGEOSTROPHIC FLW THROUGH MID
MORNING W/CORRESPONDING SUBSEQUENT FASTER ARRIVAL OF COLD POCKET
ALOFT FULLY ANTICIPATED. THIS WILL ESSENTIALLY OVERWHELM TROWAL WARM
NOSE AND LEAD TO RAPID MIX TWD HEAVY SNOW BTWN 17-20Z SW-NE ACRS THE
WRN 2/3RDS OF CWA TIED TO MAXIMIZING VERTICAL ASCENT WITHIN MID LVL
DEFORMATION ZONE ALG NOSE OF ASCENDING WARM CONVEYOR BELT. AND THUS
THE CHALLENGE OF THE DAY IS WHAT TO DO W/SNOW AMOUNTS.
BLENDED MULTI-MODEL QPF WAS UTILIZED TO DAMPEN MUCH HIGHER HIGHRES
GUIDANCE WHILE OFFSETTING LWR BOUND SPECTRAL GUIDANCE. THIS GIVES SIMILAR
AMOUNTS W/HPC YET PREFER A HEDGE WWD PLACEMENT OF MORE SIG SNOW BAND.
THROUGH 05Z...5 INCH AMOUNTS HAVE BEEN REPORTED ACRS WRN TN. HIGHER
AMOUNTS ARE CERTAINLY PLAUSIBLE...EVEN LIKELY...ESP CONSIDERING ALL
HIGHRES SOLUTIONS IMPLYING LOW TOPPED CONVN THIS AFTN WITHIN MID LVL
DEFORMATION ZONE ACRS NRN IN/SRN MI AND SREF PROBS OF 1+ INCH/HR
SNOW RATES EXCEED 70% THIS AFTN AND EVENING AND 2+ PROBS EXCEEDING
30%. NR TERM 06Z RUNS OF HRRR/RUC BOTH CONFIRMING FASTER CHG OVR AND
DVLPMNT OF 40+ DBZ RTNS THIS AFTN WITHIN DEFORMATION ZONE THUS
W/GROWING LIKELIHOOD OF EXTREME SNOWFALL RATES...POTENTIAL ACCUMS
MAY BE SIGNIFICANTLY HIGHER THAN CURRENTLY SHOWN W/SOME EXPERIMENTAL
HIGHRES SNOW ALGORITHMS INDICATING A FOOT PLUS ALG A WARSAW TO
KALAMAZOO LINE. THUS GIVEN TIMING OF CHG OVR WILL LIKELY OCCUR WELL
BFR THE AFTN COMMUTE AND POTENTIAL FOR SHORT DURATION/6+ INCH SNOW
AMOUNTS WILL HOIST A WINTER STORM WATCH FROM EARLY AFTN THROUGH 06Z
FOR GENERALLY THE WRN 2/3RDS OF CWA. FRINGE COUNTIES ALG BOTH SIDES
ARE PROBLEMATIC ESP FAR NW WHERE DVLPMNT OF STG ISOLLABARIC FLW XPCD
THIS AFTN OFF LK MI SHLD MODIFY THE BNDRY LYR SUFFICIENTLY TO
PROMOTE MORE OF A MIX AND NEGLIGIBLE ACCUMS...AND EAST W/SPECTRAL
MODEL CONSENSUS MUCH SLWR LIFTING INTENSE DEFORMATION ZONE BAND OUT
THIS EVENING. THUS THE NOD TWD A WATCH VS WARNING AT THIS POINT AND
IN LIGHT OF CHG OVR TIMING UNCERTAINTIES STILL.
REGARDLESS WHAT IS LEFT OF MID LVL DEFORMATION ZONE...LEFTOVERS
WILL RAPIDLY LIFT OUT/BREAK DOWN TWD LT EVENING/EARLY MORNING W/SNOW
ENDING QUICKLY W-E. CLDS SHLD HOLD THOUGH WITHIN LL THERMAL TROUGH
AND FLW NW LL FLW OFF THE LAKE AND WILL HOLD W/WARMER MIN BLEND
OVERNIGHT.
LONG TERM...WEDNESDAY THROUGH MONDAY
ONLY MINOR TWEAKS MADE TO THE FCST AS LATEST GUIDANCE IS SIMILAR TO
PREVIOUS GUIDANCE AND INHERITED GRIDS. A REPRIEVE FROM THE WET/WHITE
WX ANTICIPATED WEDNESDAY INTO THURSDAY AS HEIGHT RISES/SHORTWAVE
RIDGING ENSUES BEHIND TODAY`S POWERHOUSE SYSTEM. WEDNESDAY WILL
START OUT MAINLY CLOUDY (ESPECIALLY EAST) AND BREEZY...WITH CLEARING
AND DIMINISHING WINDS BY AFTERNOON. WAA ALOFT WILL BE OFFSET BY
SHALLOW MIXING AND SNOW COVER OVER MUCH OF THE AREA. WITH THIS OPTED
FOR COOLER GUIDANCE EACH DAY.
MORNING WATER VAPOR LOOP SHOWS A POTENT NORTHERN STREAM SHORTWAVE
TROUGH NEAR 145W IN THE NE PAC. THIS FEATURE WILL DIG INTO THE
WESTERN CONUS BY WEDNESDAY...WITH ENSEMBLES CONTINUING TO INDICATE
AN UPPER TROUGH FRACTURE BY THIS TIME. THE MOISTURE STARVED AND
SOMEWHAT SHEARED NRN PIECE OF THIS WAVE LOOKS TO PROPAGATE RAPIDLY
EWD THROUGH THE GREAT LAKES BY THURSDAY NIGHT/FRIDAY MORNING.
ECMWF/GFS 5-3H Q-VECTOR PROGS POINT TO A BRIEF PERIOD OF LARGE SCALE
ASCENT BYPASSING MAINLY TO THE NORTH DURING THIS TIME. AS A
RESULT...NOT EXPECTING MUCH IN THE WAY OF PRECIP BEHIND THE
ATTENDANT CDFNT LOCALLY. OPTED TO LOWER POPS TO SLIGHT CHC FOR THE
POSSIBILITY OF A FEW LGT SNOW SHOWERS.
GREATER AMPLIFICATION OF A NE PAC RIDGE WILL SUPPORT DOWNSTREAM
AMPLIFICATION THIS WEEKEND...ALLOWING ANOTHER POSITIVELY TILTED NRN
STREAM UPPER TROUGH TO DIG INTO THE CENTRAL CONUS. THIS GREATER
AMPLIFICATION WILL HELP FORCE A SRN STREAM LEAD SHORTWAVE NEWD
TOWARDS THE GREAT LAKES BY SATURDAY NIGHT/SUNDAY...BRINGING WITH IT
A BETTER CHC FOR MORE WIDESPREAD PRECIPITATION BY THIS TIME. AS
EXPECTED THIS FAR IN ADVANCE...STILL LOW CONFIDENCE WRT TO DETAILS
(TRACK/TIMING/AMPLITUDE/ETC) SO WILL RETAIN CHC POPS AND FAVOR THE
MORE CONSISTENT ECMWF WHICH HINTS AT A FARTHER NW TRACK AND MAINLY
RAIN LOCALLY. OTHERWISE...TEMPS FOR THE ENTIRE PERIOD ARE FCST TO
GENERALLY BE AT OR BELOW NORMAL.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER STORM WARNING UNTIL 1 AM EST WEDNESDAY FOR INZ006>009-
015>018-022>027-032>034.
WINTER WEATHER ADVISORY UNTIL 1 AM EST /MIDNIGHT CST/ WEDNESDAY
FOR INZ004-005-012>014-020.
MI...WINTER STORM WARNING UNTIL 1 AM EST WEDNESDAY FOR MIZ080-081.
WINTER WEATHER ADVISORY UNTIL 1 AM EST WEDNESDAY FOR MIZ078-079.
OH...WINTER STORM WARNING UNTIL 1 AM EST WEDNESDAY FOR OHZ001-002-004-
015.
LM...GALE WARNING UNTIL 10 AM EST WEDNESDAY FOR LMZ043-046.
&&
$$
SHORT TERM...T
LONG TERM...STEINWEDEL
AVIATION...SKIPPER/FISHER
UPDATE...FISHER
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1000 AM EST TUE NOV 29 2011
.HYDROLOGY...
HAVE UPDATED THE FLOOD WATCH TO AN AREAL FLOOD WARNING FOR THE
ENTIRE AREA. SATURATED GROUND FROM EARLIER RAINFALL HAS CAUSED
THE ADDITIONAL RAINFALL TO RUNOFF AND PRODUCE SOME FLOODING OF
ROADS AND RAPID RISES ON STREAMS. ADDITIONAL RAINFALL OF 1 TO
2 INCHES AND EVEN MELTED SNOW LATER TODAY IS EXPECTED TO CAUSE
WIDESPREAD AREAL FLOODING LATER TODAY.
&&
.PREV DISCUSSION... /ISSUED 446 AM EST TUE NOV 29 2011/
SHORT TERM...
DYNAMIC/IMPRESSIVE SRN STREAM WAVE CONTS TO WRAP UP ACRS WRN TN
EARLY THIS MORNING W/MATURE INTENSE TROWAL TO ITS NORTH. WIDESPREAD
MOD-HVY RAIN WAS ONGOING ACRS MUCH OF THE CWA W/HEAVIEST BANDED PCPN
ORIENTED SW-NE THROUGH ACRS THE NW HALF.
COMPLEX/MULTI-FACETED FCST GOING FWD FOR TDA AND TONIGHT. COLD CORE
LOW OVR WRN TN WILL LIFT OUT NEWD THROUGH WRN OH AND DEEPEN THROUGH LT
AFTN IN RESPONSE TO UPSTREAM NRN STREAM TROUGH MAKING QUICK EWD
PROGRESS ACRS THE UPR MIDWEST. IN FACT FULL GAMUT OF 00Z GUIDANCE
TRENDED QUICKER W/RAIN-SNOW CHG OVR AND IN LIFTING THIS DEEP SYS OUT
W/VAPOR INDICATING FTR BEGINNING TO GET PICKED UP W/RAIN CHG TO SNOW
NOW INTO SE MO/SRN IL. HWVR MODEL INTRICACIES ABOUND ESP W/TIMING OF
CHG OVR AND PLACEMENT OF MOST INTENSE PORTION OF MID LVL DEFORMATION
BAND. EARLY CONJECTURE HERE GIVES A NOD TO MODELS THAT IMPLY A
FASTER CHG OVR/WWD PLACEMENT GIVEN NRN STREAM TROUGH IS SLIGHTLY EWD
OF PRIOR 03Z RUC GUIDANCE AND QUICKER W/INFILTRATION OF LL CAA WING
ADVTG SWWD WITHIN RAPIDLY INCREASING LL AGEOSTROPHIC FLW THROUGH MID
MORNING W/CORRESPONDING SUBSEQUENT FASTER ARRIVAL OF COLD POCKET
ALOFT FULLY ANTICIPATED. THIS WILL ESSENTIALLY OVERWHELM TROWAL WARM
NOSE AND LEAD TO RAPID MIX TWD HEAVY SNOW BTWN 17-20Z SW-NE ACRS THE
WRN 2/3RDS OF CWA TIED TO MAXIMIZING VERTICAL ASCENT WITHIN MID LVL
DEFORMATION ZONE ALG NOSE OF ASCENDING WARM CONVEYOR BELT. AND THUS
THE CHALLENGE OF THE DAY IS WHAT TO DO W/SNOW AMOUNTS.
BLENDED MULTI-MODEL QPF WAS UTILIZED TO DAMPEN MUCH HIGHER HIGHRES
GUIDANCE WHILE OFFSETTING LWR BOUND SPECTRAL GUIDANCE. THIS GIVES SIMILAR
AMOUNTS W/HPC YET PREFER A HEDGE WWD PLACEMENT OF MORE SIG SNOW BAND.
THROUGH 05Z...5 INCH AMOUNTS HAVE BEEN REPORTED ACRS WRN TN. HIGHER
AMOUNTS ARE CERTAINLY PLAUSIBLE...EVEN LIKELY...ESP CONSIDERING ALL
HIGHRES SOLUTIONS IMPLYING LOW TOPPED CONVN THIS AFTN WITHIN MID LVL
DEFORMATION ZONE ACRS NRN IN/SRN MI AND SREF PROBS OF 1+ INCH/HR
SNOW RATES EXCEED 70% THIS AFTN AND EVENING AND 2+ PROBS EXCEEDING
30%. NR TERM 06Z RUNS OF HRRR/RUC BOTH CONFIRMING FASTER CHG OVR AND
DVLPMNT OF 40+ DBZ RTNS THIS AFTN WITHIN DEFORMATION ZONE THUS
W/GROWING LIKELIHOOD OF EXTREME SNOWFALL RATES...POTENTIAL ACCUMS
MAY BE SIGNIFICANTLY HIGHER THAN CURRENTLY SHOWN W/SOME EXPERIMENTAL
HIGHRES SNOW ALGORITHMS INDICATING A FOOT PLUS ALG A WARSAW TO
KALAMAZOO LINE. THUS GIVEN TIMING OF CHG OVR WILL LIKELY OCCUR WELL
BFR THE AFTN COMMUTE AND POTENTIAL FOR SHORT DURATION/6+ INCH SNOW
AMOUNTS WILL HOIST A WINTER STORM WATCH FROM EARLY AFTN THROUGH 06Z
FOR GENERALLY THE WRN 2/3RDS OF CWA. FRINGE COUNTIES ALG BOTH SIDES
ARE PROBLEMATIC ESP FAR NW WHERE DVLPMNT OF STG ISOLLABARIC FLW XPCD
THIS AFTN OFF LK MI SHLD MODIFY THE BNDRY LYR SUFFICIENTLY TO
PROMOTE MORE OF A MIX AND NEGLIGIBLE ACCUMS...AND EAST W/SPECTRAL
MODEL CONSENSUS MUCH SLWR LIFTING INTENSE DEFORMATION ZONE BAND OUT
THIS EVENING. THUS THE NOD TWD A WATCH VS WARNING AT THIS POINT AND
IN LIGHT OF CHG OVR TIMING UNCERTAINTIES STILL.
REGARDLESS WHAT IS LEFT OF MID LVL DEFORMATION ZONE...LEFTOVERS
WILL RAPIDLY LIFT OUT/BREAK DOWN TWD LT EVENING/EARLY MORNING W/SNOW
ENDING QUICKLY W-E. CLDS SHLD HOLD THOUGH WITHIN LL THERMAL TROUGH
AND FLW NW LL FLW OFF THE LAKE AND WILL HOLD W/WARMER MIN BLEND
OVERNIGHT.
LONG TERM...WEDNESDAY THROUGH MONDAY
ONLY MINOR TWEAKS MADE TO THE FCST AS LATEST GUIDANCE IS SIMILAR TO
PREVIOUS GUIDANCE AND INHERITED GRIDS. A REPRIEVE FROM THE WET/WHITE
WX ANTICIPATED WEDNESDAY INTO THURSDAY AS HEIGHT RISES/SHORTWAVE
RIDGING ENSUES BEHIND TODAY`S POWERHOUSE SYSTEM. WEDNESDAY WILL
START OUT MAINLY CLOUDY (ESPECIALLY EAST) AND BREEZY...WITH CLEARING
AND DIMINISHING WINDS BY AFTERNOON. WAA ALOFT WILL BE OFFSET BY
SHALLOW MIXING AND SNOW COVER OVER MUCH OF THE AREA. WITH THIS OPTED
FOR COOLER GUIDANCE EACH DAY.
MORNING WATER VAPOR LOOP SHOWS A POTENT NORTHERN STREAM SHORTWAVE
TROUGH NEAR 145W IN THE NE PAC. THIS FEATURE WILL DIG INTO THE
WESTERN CONUS BY WEDNESDAY...WITH ENSEMBLES CONTINUING TO INDICATE
AN UPPER TROUGH FRACTURE BY THIS TIME. THE MOISTURE STARVED AND
SOMEWHAT SHEARED NRN PIECE OF THIS WAVE LOOKS TO PROPAGATE RAPIDLY
EWD THROUGH THE GREAT LAKES BY THURSDAY NIGHT/FRIDAY MORNING.
ECMWF/GFS 5-3H Q-VECTOR PROGS POINT TO A BRIEF PERIOD OF LARGE SCALE
ASCENT BYPASSING MAINLY TO THE NORTH DURING THIS TIME. AS A
RESULT...NOT EXPECTING MUCH IN THE WAY OF PRECIP BEHIND THE
ATTENDANT CDFNT LOCALLY. OPTED TO LOWER POPS TO SLIGHT CHC FOR THE
POSSIBILITY OF A FEW LGT SNOW SHOWERS.
GREATER AMPLIFICATION OF A NE PAC RIDGE WILL SUPPORT DOWNSTREAM
AMPLIFICATION THIS WEEKEND...ALLOWING ANOTHER POSITIVELY TILTED NRN
STREAM UPPER TROUGH TO DIG INTO THE CENTRAL CONUS. THIS GREATER
AMPLIFICATION WILL HELP FORCE A SRN STREAM LEAD SHORTWAVE NEWD
TOWARDS THE GREAT LAKES BY SATURDAY NIGHT/SUNDAY...BRINGING WITH IT
A BETTER CHC FOR MORE WIDESPREAD PRECIPITATION BY THIS TIME. AS
EXPECTED THIS FAR IN ADVANCE...STILL LOW CONFIDENCE WRT TO DETAILS
(TRACK/TIMING/AMPLITUDE/ETC) SO WILL RETAIN CHC POPS AND FAVOR THE
MORE CONSISTENT ECMWF WHICH HINTS AT A FARTHER NW TRACK AND MAINLY
RAIN LOCALLY. OTHERWISE...TEMPS FOR THE ENTIRE PERIOD ARE FCST TO
GENERALLY BE AT OR BELOW NORMAL.
AVIATION...
XPC IFR CIGS TO HOLD THROUGH THE PD W/GENERALLY MVFR VSBYS
PREFERRED IN RAIN UNTIL THIS AFTN WHEN CHG OVR TO SNOW OCCURS. PD
OF LIFR CONDS LIKELY LT THIS AFTN/EARLY EVENING IN +SN W/LONGER
DURATION XPCD AT KSBN. WILL ATTEMPT SOME REFINED TIMING W/12Z ISSUANCE.
OTHERWISE GRADIENT WINDS ARE COMING UP NOW W/SFC GUSTS AOA 25KTS
THROUGH EARLY EVENING.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER STORM WATCH FROM 1 PM EST /NOON CST/ THIS AFTERNOON
THROUGH LATE TONIGHT FOR INZ004>009-012>018-020-022>025-032.
MI...WINTER STORM WATCH FROM 1 PM EST THIS AFTERNOON THROUGH LATE
TONIGHT FOR MIZ078>081.
OH...WINTER STORM WATCH FROM 1 PM EST THIS AFTERNOON THROUGH LATE
TONIGHT FOR OHZ001.
LM...GALE WARNING UNTIL 10 AM EST WEDNESDAY FOR LMZ043-046.
&&
$$
SHORT TERM...T
LONG TERM...STEINWEDEL
AVIATION...T
AREA FORECAST DISCUSSION...CORRECTED
NWS NORTHERN INDIANA
446 AM EST TUE NOV 29 2011
.SHORT TERM...
DYNAMIC/IMPRESSIVE SRN STREAM WAVE CONTS TO WRAP UP ACRS WRN TN
EARLY THIS MORNING W/MATURE INTENSE TROWAL TO ITS NORTH. WIDESPREAD
MOD-HVY RAIN WAS ONGOING ACRS MUCH OF THE CWA W/HEAVIEST BANDED PCPN
ORIENTED SW-NE THROUGH ACRS THE NW HALF.
COMPLEX/MULTI-FACETED FCST GOING FWD FOR TDA AND TONIGHT. COLD CORE
LOW OVR WRN TN WILL LIFT OUT NEWD THROUGH WRN OH AND DEEPEN THROUGH LT
AFTN IN RESPONSE TO UPSTREAM NRN STREAM TROUGH MAKING QUICK EWD
PROGRESS ACRS THE UPR MIDWEST. IN FACT FULL GAMUT OF 00Z GUIDANCE
TRENDED QUICKER W/RAIN-SNOW CHG OVR AND IN LIFTING THIS DEEP SYS OUT
W/VAPOR INDICATING FTR BEGINNING TO GET PICKED UP W/RAIN CHG TO SNOW
NOW INTO SE MO/SRN IL. HWVR MODEL INTRICACIES ABOUND ESP W/TIMING OF
CHG OVR AND PLACEMENT OF MOST INTENSE PORTION OF MID LVL DEFORMATION
BAND. EARLY CONJECTURE HERE GIVES A NOD TO MODELS THAT IMPLY A
FASTER CHG OVR/WWD PLACEMENT GIVEN NRN STREAM TROUGH IS SLIGHTLY EWD
OF PRIOR 03Z RUC GUIDANCE AND QUICKER W/INFILTRATION OF LL CAA WING
ADVTG SWWD WITHIN RAPIDLY INCREASING LL AGEOSTROPHIC FLW THROUGH MID
MORNING W/CORRESPONDING SUBSEQUENT FASTER ARRIVAL OF COLD POCKET
ALOFT FULLY ANTICIPATED. THIS WILL ESSENTIALLY OVERWHELM TROWAL WARM
NOSE AND LEAD TO RAPID MIX TWD HEAVY SNOW BTWN 17-20Z SW-NE ACRS THE
WRN 2/3RDS OF CWA TIED TO MAXIMIZING VERTICAL ASCENT WITHIN MID LVL
DEFORMATION ZONE ALG NOSE OF ASCENDING WARM CONVEYOR BELT. AND THUS
THE CHALLENGE OF THE DAY IS WHAT TO DO W/SNOW AMOUNTS.
BLENDED MULTI-MODEL QPF WAS UTILIZED TO DAMPEN MUCH HIGHER HIGHRES
GUIDANCE WHILE OFFSETTING LWR BOUND SPECTRAL GUIDANCE. THIS GIVES SIMILAR
AMOUNTS W/HPC YET PREFER A HEDGE WWD PLACEMENT OF MORE SIG SNOW BAND.
THROUGH 05Z...5 INCH AMOUNTS HAVE BEEN REPORTED ACRS WRN TN. HIGHER
AMOUNTS ARE CERTAINLY PLAUSIBLE...EVEN LIKELY...ESP CONSIDERING ALL
HIGHRES SOLUTIONS IMPLYING LOW TOPPED CONVN THIS AFTN WITHIN MID LVL
DEFORMATION ZONE ACRS NRN IN/SRN MI AND SREF PROBS OF 1+ INCH/HR
SNOW RATES EXCEED 70% THIS AFTN AND EVENING AND 2+ PROBS EXCEEDING
30%. NR TERM 06Z RUNS OF HRRR/RUC BOTH CONFIRMING FASTER CHG OVR AND
DVLPMNT OF 40+ DBZ RTNS THIS AFTN WITHIN DEFORMATION ZONE THUS
W/GROWING LIKELIHOOD OF EXTREME SNOWFALL RATES...POTENTIAL ACCUMS
MAY BE SIGNIFICANTLY HIGHER THAN CURRENTLY SHOWN W/SOME EXPERIMENTAL
HIGHRES SNOW ALGORITHMS INDICATING A FOOT PLUS ALG A WARSAW TO
KALAMAZOO LINE. THUS GIVEN TIMING OF CHG OVR WILL LIKELY OCCUR WELL
BFR THE AFTN COMMUTE AND POTENTIAL FOR SHORT DURATION/6+ INCH SNOW
AMOUNTS WILL HOIST A WINTER STORM WATCH FROM EARLY AFTN THROUGH 06Z
FOR GENERALLY THE WRN 2/3RDS OF CWA. FRINGE COUNTIES ALG BOTH SIDES
ARE PROBLEMATIC ESP FAR NW WHERE DVLPMNT OF STG ISOLLABARIC FLW XPCD
THIS AFTN OFF LK MI SHLD MODIFY THE BNDRY LYR SUFFICIENTLY TO
PROMOTE MORE OF A MIX AND NEGLIGIBLE ACCUMS...AND EAST W/SPECTRAL
MODEL CONSENSUS MUCH SLWR LIFTING INTENSE DEFORMATION ZONE BAND OUT
THIS EVENING. THUS THE NOD TWD A WATCH VS WARNING AT THIS POINT AND
IN LIGHT OF CHG OVR TIMING UNCERTAINTIES STILL.
REGARDLESS WHAT IS LEFT OF MID LVL DEFORMATION ZONE...LEFTOVERS
WILL RAPIDLY LIFT OUT/BREAK DOWN TWD LT EVENING/EARLY MORNING W/SNOW
ENDING QUICKLY W-E. CLDS SHLD HOLD THOUGH WITHIN LL THERMAL TROUGH
AND FLW NW LL FLW OFF THE LAKE AND WILL HOLD W/WARMER MIN BLEND
OVERNIGHT.
&&
.LONG TERM...WEDNESDAY THROUGH MONDAY
ONLY MINOR TWEAKS MADE TO THE FCST AS LATEST GUIDANCE IS SIMILAR TO
PREVIOUS GUIDANCE AND INHERITED GRIDS. A REPRIEVE FROM THE WET/WHITE
WX ANTICIPATED WEDNESDAY INTO THURSDAY AS HEIGHT RISES/SHORTWAVE
RIDGING ENSUES BEHIND TODAY`S POWERHOUSE SYSTEM. WEDNESDAY WILL
START OUT MAINLY CLOUDY (ESPECIALLY EAST) AND BREEZY...WITH CLEARING
AND DIMINISHING WINDS BY AFTERNOON. WAA ALOFT WILL BE OFFSET BY
SHALLOW MIXING AND SNOW COVER OVER MUCH OF THE AREA. WITH THIS OPTED
FOR COOLER GUIDANCE EACH DAY.
MORNING WATER VAPOR LOOP SHOWS A POTENT NORTHERN STREAM SHORTWAVE
TROUGH NEAR 145W IN THE NE PAC. THIS FEATURE WILL DIG INTO THE
WESTERN CONUS BY WEDNESDAY...WITH ENSEMBLES CONTINUING TO INDICATE
AN UPPER TROUGH FRACTURE BY THIS TIME. THE MOISTURE STARVED AND
SOMEWHAT SHEARED NRN PIECE OF THIS WAVE LOOKS TO PROPAGATE RAPIDLY
EWD THROUGH THE GREAT LAKES BY THURSDAY NIGHT/FRIDAY MORNING.
ECMWF/GFS 5-3H Q-VECTOR PROGS POINT TO A BRIEF PERIOD OF LARGE SCALE
ASCENT BYPASSING MAINLY TO THE NORTH DURING THIS TIME. AS A
RESULT...NOT EXPECTING MUCH IN THE WAY OF PRECIP BEHIND THE
ATTENDANT CDFNT LOCALLY. OPTED TO LOWER POPS TO SLIGHT CHC FOR THE
POSSIBILITY OF A FEW LGT SNOW SHOWERS.
GREATER AMPLIFICATION OF A NE PAC RIDGE WILL SUPPORT DOWNSTREAM
AMPLIFICATION THIS WEEKEND...ALLOWING ANOTHER POSITIVELY TILTED NRN
STREAM UPPER TROUGH TO DIG INTO THE CENTRAL CONUS. THIS GREATER
AMPLIFICATION WILL HELP FORCE A SRN STREAM LEAD SHORTWAVE NEWD
TOWARDS THE GREAT LAKES BY SATURDAY NIGHT/SUNDAY...BRINGING WITH IT
A BETTER CHC FOR MORE WIDESPREAD PRECIPITATION BY THIS TIME. AS
EXPECTED THIS FAR IN ADVANCE...STILL LOW CONFIDENCE WRT TO DETAILS
(TRACK/TIMING/AMPLITUDE/ETC) SO WILL RETAIN CHC POPS AND FAVOR THE
MORE CONSISTENT ECMWF WHICH HINTS AT A FARTHER NW TRACK AND MAINLY
RAIN LOCALLY. OTHERWISE...TEMPS FOR THE ENTIRE PERIOD ARE FCST TO
GENERALLY BE AT OR BELOW NORMAL.
&&
.AVIATION...
XPC IFR CIGS TO HOLD THROUGH THE PD W/GENERALLY MVFR VSBYS
PREFERRED IN RAIN UNTIL THIS AFTN WHEN CHG OVR TO SNOW OCCURS. PD
OF LIFR CONDS LIKELY LT THIS AFTN/EARLY EVENING IN +SN W/LONGER
DURATION XPCD AT KSBN. WILL ATTEMPT SOME REFINED TIMING W/12Z ISSUANCE.
OTHERWISE GRADIENT WINDS ARE COMING UP NOW W/SFC GUSTS AOA 25KTS
THROUGH EARLY EVENING.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...FLOOD WATCH THROUGH THIS EVENING FOR INZ003>009-012>018-020-
022>027-032>034.
WINTER STORM WATCH FROM 1 PM EST /NOON CST/ THIS AFTERNOON
THROUGH LATE TONIGHT FOR INZ004>009-012>018-020-022>025-032.
MI...FLOOD WATCH THROUGH THIS EVENING FOR MIZ077>081.
WINTER STORM WATCH FROM 1 PM EST THIS AFTERNOON THROUGH LATE
TONIGHT FOR MIZ078>081.
OH...FLOOD WATCH THROUGH THIS EVENING FOR OHZ001-002-004-005-015-016-
024-025.
WINTER STORM WATCH FROM 1 PM EST THIS AFTERNOON THROUGH LATE
TONIGHT FOR OHZ001.
LM...GALE WARNING UNTIL 10 AM EST WEDNESDAY FOR LMZ043-046.
&&
$$
SHORT TERM...T
LONG TERM...STEINWEDEL
AVIATION...T
AREA FORECAST DISCUSSION
NWS TOPEKA KS
540 PM CST WED NOV 30 2011
...UPDATE TO AVIATION...
.DISCUSSION...
SHORT RANGE FORECAST (TONIGHT AND THURSDAY)...
20Z WATER VAPOR IMAGERY AND ASSOCIATED 500 MB RUC ANALYSIS SHOWS A
MID/UPPER LEVEL TROUGH OVER THE APPALACHIAN MOUNTAINS...WITH ANOTHER
H5 LOW DIVING SOUTHWARD THROUGH THE NORTHERN ROCKIES. BETWEEN THE
TWO TROUGHS IS A FLATTENED UPPER RIDGE OVER THE CENTRAL PLAINS WHICH
HAS BROUGHT FAIR CONDITIONS TO THE AREA. SOUTHERLY FLOW ALONG THE
EASTERN EDGE OF A DEEPENING SURFACE TROUGH ADVECTED WARM AIR INTO
NORTHEAST KANSAS...ALLOWING TEMPS TO REACH THE MID 50S ACROSS MUCH
OF THE AREA. EXPECT THE SURFACE TROUGH TO PUSH SOUTHEASTWARD AHEAD
OF AN ADVANCING SURFACE RIDGE...WHICH WILL BRING A COLD FRONT
THROUGH THE AREA BY MID DAY ON THURSDAY. EXPECT COOLER/DRYER AIR TO
MOVE IN BEHIND THE COLD FRONT FOR THURSDAY...ESPECIALLY FOR AREAS
ACROSS NORTH CENTRAL KANSAS WHICH WILL SEE THE FRONTAL PASSAGE
BEFORE PEAK HEATING. AREAS OF EASTERN KANSAS MAY SEE ANOTHER MILD
DAY AS SOUTHERLY FLOW SHOULD PERSIST THROUGH MUCH OF THE EARLY
AFTERNOON BEFORE THE FRONTAL PASSAGE IN THE EARLY EVENING. EXPECT
STRATUS TO BUILD IN BEHIND THE FRONT WHICH COULD POSSIBLY BRING SOME
SCATTERED SPRINKLES OR POSSIBLY SOME SNOW FLURRIES TO AREAS OF NORTH
CENTRAL KANSAS ON THURSDAY.
LEIGHTON
LONG TERM...THU NIGHT THROUGH NEXT WEDS.
FCST FOCUS REMAINS ON THE EVOLUTION OF STORM SYSTEM FRI INTO SAT.
RECENT MODEL GUIDANCE AND TRENDS CONTINUE TO SUGGEST A SLOWER
TRACK THAN THAT INDICATED BY THE NAM. GFS/ECMWF ARE THE FAVORED
MODELS FOR THIS FCST.
INITIAL MODIFIED POLAR AIRMASS WILL SETTLE INTO THE AREA THU
NIGHT WITH LIGHT WINDS AND SEASONABLY COLD TEMPS. BY FRI
AM...SOUTHERLY SFC WINDS WILL DEVELOP AS THE WESTERN U.S. LONGWAVE
TROUGH BEGINS TO BECOME PROGRESSIVE. LIFT WILL INCREASE THROUGH
THE DAY WITH SATURATION AND PRECIP DEVELOPMENT EXPECTED BY FRI
NIGHT. THERMAL PROFILES SUGGEST MAINLY RAIN EXCEPT FOR THE
NORTHWEST THIRD OF THE CWA WHERE DEPENDING ON THE WET BULB TEMPS
THERE MAY BE A RISK FOR FREEZING RAIN. GFS RAW MODEL NEAR SFC
TEMPS ARE WARMER THAN THE NUMERICAL MODEL GUIDANCE WHICH SUGGESTS
LOWS IN THE UPPER 20S TO LOWER 30S ACROSS THE NW THIRD SO
CONFIDENCE IN ICE THREAT REMAINS LOW AT THIS TIME. RIGHT NOW AREAS
ROUGHLY FROM ABILENE TO SENECA AND NW COULD SEE FREEZING PRECIP
FRI NIGHT. GFS CONTINUES TO WARM BOUNDARY LAYER TEMPS UP EARLY SAT
SUCH THAT ANY FZRA/ICE RISK SHOULD DECREASE HOWEVER WIDESPREAD
RAIN...SOME HEAVY SHOULD PERSIST ACROSS THE AREA AS THE UPPER
TROUGH MOVES THROUGH THE AREA AND THE SFC LOW TRACKS ACROSS
EASTERN KS. PRECIP SHOULD MIX WITH OR CHANGE TO SLEET OR SNOW FROM
WEST TO EAST BY LATER SAT/SAT NIGHT AS COLDER AIR ARRIVES ON THE
BACK SIDE OF THE SYSTEM. HOWEVER GFS ALSO SHOWS A DRY SLOT LATER
SAT AFTERNOON WHICH COULD BRING A BREAK IN THE PRECIP AND WOULD
ALSO LIMIT THE SNOW THREAT ACROSS NORTH-CENTRAL KS.
ALL IN ALL...LOOK FOR ANOTHER ROUND OF WIDESPREAD HEAVY RAINS OF 1
TO 2.5 INCHES FRI NIGHT INTO SAT WITH WHAT APPEARS TO BE A LOW RISK
FOR FREEZING PRECIP FRI NIGHT ACROSS PARTS OF THE AREA.
THE PATTERN LOOKS QUITE ACTIVE FOR THE REGION INTO NEXT WEEK WITH
ADDITIONAL POLAR COLD FRONTS EXPECTED TO DRIVE SOUTHWARD THROUGH
THE PLAINS. THE ACTUAL LONGWAVE TROUGH AXIS MAY NOT PASS THROUGH
THE REGION UNTIL MID WEEK SO CLOUDS/SOME LOW PRECIP CHCS MAY
LINGER ACROSS SOUTHERN KS BUT IT LOOKS DRY BUT COLD ACROSS NE KS.
CO
&&
.AVIATION...
MAIN CONCERN THIS PERIOD WILL BE TIMING OF COLD FRONTAL PASSAGE ON
THURSDAY. CURRENTLY LOOKING LIKE WINDS SHOULD SHIFT AT MHK AROUND
14Z THEN AT TOP AND FOE IN THE 16Z-17Z PERIOD. FORECAST SOUNDINGS
AND TIME SECTIONS SHOW STRATUS FORMING NEAR THE END OF THE PERIOD
WITH CLOUDS BASES REMAINING VFR. MVFR CIGS LOOK TO MOVE IN AFTER
02/00Z.
53
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
331 PM CST TUE NOV 29 2011
.DISCUSSION...
SHORT RANGE FORECAST (TONIGHT AND WEDNESDAY)...
20Z WATER VAPOR IMAGERY AND ASSOCIATED 500 MB RUC ANALYSIS SHOWS A
DEEP CUT OFF LOW PRESSURE SYSTEM SLOWLY MOVING NORTHEASTWARD THROUGH
THE OHIO RIVER VALLEY...BRINGING NORTHWESTERLY MID LEVEL FLOW OVER
THE CENTRAL U.S. A SHORTWAVE TROUGH EMBEDDED WITHIN THE NORTHWEST
FLOW IS CURRENTLY PUSHING THROUGH THE AREA...HOWEVER MEAGER LIFT
FROM THIS QUICKLY MOVING SHORTWAVE WILL ONLY BRING SOME SCATTERED
HIGH CLOUDS FOR THIS AFTERNOON. AT THE SURFACE A SURFACE RIDGE OF
HIGH PRESSURE CURRENTLY SITS OVER CENTRAL KANSAS CREATING TIGHT
GRADIENT WITH SUBSEQUENT GUSTY NORTH-NORTHWEST WINDS ACROSS FAR
EASTERN KANSAS. A NARROW BAND OF DRY AIR HAS MOVED INTO NORTH
CENTRAL KANSAS AS DEWPOINTS HAVE MIXED INTO THE SINGLE
DIGITS...HOWEVER DUE TO THE LIGHT WINDS NEAR THE CENTER OF THE
SURFACE HIGH...FIRE DANGER IS NOT VERY HIGH IN THIS AREA DESPITE THE
VERY DRY AIR.
OVERNIGHT THE SURFACE RIDGE MOVES OVER NORTHEAST KANSAS CAUSING
WINDS TO GO CALM. WITH SKIES CLEARING OUT RADIATIONAL COOLING WILL
ALLOW TEMPERATURES TO DROP INTO THE LOWER TO MID 20S. WOULD HAVE
GONE A LITTLE COOLER IN NORTH CENTRAL KANSAS BUT SOUTHERLY FLOW
ALONG THE WESTERN EDGE OF THE EASTWARD MOVING SURFACE RIDGE WILL
ALLOW FOR SOME WEAK WARM AIR ADVECTION AS WELL AS SOME BOUNDARY
LAYER MIXING. THESE FACTORS WILL HELP TO KEEP TEMPERATURES A LITTLE
WARMER THAN AREAS FURTHER EAST. LOW LYING AREAS AND RIVER VALLEYS
EAST OF HIGHWAY 75 COULD SEE TEMPS DROP INTO THE UPPER TEENS AS
SOUTHERLY FLOW WILL LIKELY NOT BEGIN IN THESE AREAS UNTIL EARLY WED
MORNING.
WEDNESDAY WILL BRING ANOTHER MOSTLY CLEAR DAY WITH SLIGHTLY WARMER
TEMPERATURES THAN TUESDAY. SOUTHERLY FLOW WILL ALLOW FOR WARM AIR
ADVECTION EAST OF A DEEPENING SURFACE TROUGH WHICH WILL COME OFF THE
WESTERN HIGH PLAINS AND MOVE EAST INTO THE CENTRAL PLAINS. UTILIZED
A MIX DOWN METHOD FROM THE 900 MB LEVEL FOR WEDNESDAYS HIGHS.
TIGHTENING SURFACE PRESSURE GRADIENT BETWEEN THE DEEPENING LOW AND
THE DEPARTING SURFACE HIGH WILL CAUSE THE SOUTHERLY WINDS TO PICK UP
IN INTENSITY THROUGHOUT THE DAY ON WEDNESDAY.
JL
EXTENDED RANGE FORECAST (WEDNESDAY NIGHT THROUGH TUESDAY)...
AN UPPER LEVEL TROUGH WILL DIG SOUTHWARD ACROSS THE WESTERN CONUS
INTO THE DESERT SOUTHWEST BY THURSDAY EVENING. A MINOR H5 WILL MOVE
EAST ACROSS THE NORTHERN AND CENTRAL PLAINS WEDNESDAY NIGHT.
LOW-LEVEL CAA ACROSS THE NORTHERN PLAINS WILL CAUSE A SURFACE COLD
FRONT TO PUSH SOUTHWARD ACROSS THE CWA THURSDAY MORNING. HIGHS MAY
OCCUR DURING THE MID AND LATE MORNING HOURS ON THURSDAY ACROSS
SOUTHEAST KS...WITH TEMPERATURES HOLDING STEADY OR SLOWLY FALLING
INTO THE LOWER 40S BY AFTERNOON. NORTH WINDS WILL INCREASE 20 TO 25
MPH WITH GUSTS OF 35 TO 45 MPH BEHIND THE COLD FRONT. THERE MAY BE
SOME SNOW FLURRIES EARLY THURSDAY MORNING ACROSS THE NORTHERN
COUNTIES OF THE CWA.
FRIDAY...WILL BE COOL WITH INCREASING HIGH CLOUDINESS. WINDS WILL
SHIFT TO THE SOUTHEAST BY LATE AFTERNOON AS A LEE SFC TROUGH DEEPENS
ACROSS THE HIGH PLAINS. HIGHS ON FRIDAY WILL ONLY REACH THE MID TO
UPPER 30S. THE NAM MODEL SOLUTION HAS BEEN VERY INCONSISTENT AND
ERRONEOUS THE PAST 48 HOURS. THE NAM IS WAY TOO PROGRESSIVE LIFTING
THE CLOSED UPPER LOW INTO THE SOUTHERN HIGH PLAINS LATE FRIDAY
AFTERNOON. IF FOR SOME REASON IT WERE TO VERIFY THEN PRECIP MAY
BEGIN DEVELOPING ACROSS THE SOUTHERN COUNTIES OF THE CWA LATE FRIDAY
AFTERNOON AND SPREAD NORTHWARD INTO THE EARLY EVENING HOURS. ALL
OTHER OPERATIONAL NUMERICAL MODELS SHOW THE CLOSED UPPER LOW
REMAINING ACROSS THE DESERT SOUTHWEST INTO FRIDAY NIGHT.
FRIDAY NIGHT THROUGH SATURDAY NIGHT...A PIECE OF THE UPPER LOW
ACROSS THE DESERT SOUTHWEST WILL LIFT NORTHEAST INTO THE CENTRAL
PLAINS ON SATURDAY. THE ECMWF MODEL SHOWS STRONG WAA DEVELOPING
FRIDAY NIGHT WHICH SHOULD CAUSE SFC TEMPS AND DEWPOINTS TO RISE
ABOVE FREEZING ACROSS MUCH OF THE CWA BY 6Z SAT. THE GFS AND GEM
HAVE BEEN CONVERGING TOWARDS THE ECMWF...BUT CONTINUE TO BE A BIT
COOLER. I WILL BE LEANING A BIT MORE TOWARDS THE ECMWF DURING THIS
FORECAST PERIOD. LOW TEMPERATURES WILL OCCUR DURING THE MID EVENING
HOURS OF FRIDAY...THEN SLOWLY RISE THROUGH THE NIGHT. ISENTROPIC
LIFT AND ASCENT AHEAD OF THE APPROACHING H5 TROUGH WILL CAUSE LIGHT
RAIN TO DEVELOP. IF THERE IS ENOUGH LOW-LEVEL DRY AIR IN PLACE AS
THE RAIN DEVELOPS THEN WET-BULB COOLING MAY ALLOW SURFACE
TEMPERATURES ACROSS THE NORTHERN AND WESTERN COUNTIES TO DROP BELOW
FREEZING. THERE MAY BE SOME LIGHT PERIODS OF FREEZING RAIN FRIDAY
EVENING BEFORE IT CHANCES TO LIGHT RAIN. ROAD SURFACE ARE FAIRLY
WARM...THUS THE ONLY SLICKS SPOTS THAT MAY DEVELOP FRIDAY EVENING
MAY BE ON BRIDGES AND OTHER ELEVATED ROAD SURFACES.
THE RAIN ON SATURDAY MAY BEGIN TO MIX WITH SNOW ACROSS NORTH CENTRAL
KS DURING THE AFTERNOON HOURS AS THE H5 TROUGH LIFTS NORTHEAST
ACROSS CENTRAL KS INTO EASTERN NE. THE NORTHERN COUNTIES MAY SEE A
PERIOD OF LIGHT SNOW SATURDAY NIGHT...THE RAIN WILL MIX WITH SNOW
ACROSS THE REMAINDER OF THE CWA THROUGH THE EVENING HOURS. THERE MAY
BE A BRIEF PERIOD OF LIGHT SNOW ACROSS NORTHEAST AND EAST CENTRAL KS
BEFORE THE PRECIP MOVES EAST OF THE CWA LATE SATURDAY NIGHT INTO
SUNDAY MORNING. ATTM...THE ACCUMULATING SNOW WILL MOST LIKELY
REMAIN WEST AND NORTH OF THE CWA...FROM WEST CENTRAL KS INTO EASTERN
NE WHERE SEVERAL INCHES OF SNOW MAY ACCUMULATE. THE NORTH CENTRAL
COUNTIES MAY SEE AROUND AN INCH OF SNOW ON GRASSY SURFACES SATURDAY
NIGHT. HIGHS ON SATURDAY WILL REACH THE LOWER TO MID 40S SOUTH OF
I-70 WITH MID TO UPPER 30S NORTH OF I-70. OVERNIGHT LOWS ON SATURDAY
WILL SLOWLY DROP INTO THE 20S.
SUNDAY THROUGH TUESDAY...THE MAIN H5 LOW WILL REMAIN CUTOFF ACROSS
THE SOUTHWEST CONUS AS A LONGER WAVE LENGTH H5 TROUGH DEVELOPS
ACROSS THE EASTERN CONUS. NORTHWEST FLOW ALOFT AND A COLD SFC HIGH
PRESSURE WILL KEEP HIGHS IN THE MID 30S AND OVERNIGHT LOWS IN THE
TEENS AND LOWER 20S.
GARGAN
&&
.AVIATION...
VFR CONDITIONS EXPECTED THROUGH NEXT 24 HOURS...WITH WINDS
SWITCHING FROM THE NORTH TO SOUTH AROUND 09 Z ON WEDNESDAY MORNING.
JL
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CARIBOU ME
930 PM EST WED NOV 30 2011
.SYNOPSIS...
LOW PRESSURE WILL LIFT WEST OF THE AREA TODAY PULLING A COLD FRONT
ACROSS THE REGION. HIGH PRESSURE WILL BUILD EAST TONIGHT...THEN
CROSS THE REGION THURSDAY. A WEAK DISTURBANCE WILL CROSS THE
REGION FRIDAY.
&&
.NEAR TERM /THROUGH THURSDAY/...
.UPDATE...
USED THE NAM12 AND RUC FOR THE POPS TO KEEP THE HIGHEST PERCENTAGES
ACROSS THE WESTERN AND NORTHWESTERN AREAS OVERNIGHT AS SFC TROF
SWINGS THROUGH THE CWA. LAPS AND SATL IMAGERY WAS USED FOR THE SKY
GRIDS IN CONJUNCTION W/THE GEM. TEMPERATURES WERE MODIFIED UPWARD
BASED ON CLOUDS AND HIGHER DEWPOINTS. IT LOOKS LIKE COLDER AIR
WILL BE HELD OFF A FEW HOURS MORE.
SEE MARINE SECTION BELOW.
.PREVIOUS DISCUSSION...
WHATS LEFT OF STEADIER RN SHWRS IS WANING ACROSS ERN NB WHILE NEW
SHWRS ARE FORMING OVR NW ME AHEAD OF AN UPPER TROF AND SECONDARY
COLD APCHG FROM ERN QB. SHOWERS WILL BE POSSIBLE WELL INTO THE EVE
ACROSS NRN PTNS OF THE FA...POSSIBLY ENDING AS FLURRIES LATE TNGT.
MOST OF THE TEMP FALL OVRNGT WILL OCCUR LATE BEHIND THE SECONDARY
COLD FRONT... WHICH HAS THE GREATER IMPACT OF LLVL COLD ADVCN.
SKIES SHOULD CLR EVEN ACROSS NRN PTNS OF THE FA BEHIND THE UPPER
TROF VERY LATE TNGT INTO ERLY THU MORN...ALLOWING FOR MSLY SUNNY
SKIES AND SOMEWHAT CONDITIONS FOR THU. AFTER REACHING SIG COLDER...
BUT STILL ABV NORMAL OVRNGT LOW TEMPS DAYBREAK THU...HI TEMPS THU
WHICH WILL BE 20 TO 30 DEG F COOLER THAN TDY...FEELING BRISK IN
COMPARISON.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
A WEAK AREA OF HIGH PRESSURE WILL BUILD ACROSS THE REGION IN
ADVANCE OF A WEAK DISTURBANCE APPROACHING FROM THE WEST. MAINLY
CLEAR SKIES THURSDAY EVENING WILL GIVE WAY TO INCREASING CLOUDS
LATER THURSDAY NIGHT. A FAIRLY GOOD PERIOD OF RADIATIONAL COOLING
IS EXPECTED BEFORE CLOUDS INCREASE LATER THURSDAY NIGHT WITH LOWS
IN THE TEENS NORTH AND LOWER 20S DOWNEAST. EXPECT MOSTLY CLOUDY
SKIES ON FRIDAY WITH THE CHANCE FOR SNOW SHOWERS MAINLY ACROSS
NORTHERN AREAS AS THE SHORT WAVES MOVE EAST ACROSS THE REGION.
HIGH PRESSURE WILL BUILD IN FROM THE WEST FRIDAY NIGHT WITH
CLEARING SKIES. HIGH PRESSURE WILL SLIDE ACROSS THE REGION
SATURDAY WITH FAIR WEATHER AND SEASONABLY COOL TEMPERATURES
EXPECTED.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THOUGH THE INTENSITY OF A FRONTAL SYSTEM TRACKING ACROSS THE
CENTRAL UNITED STATES EARLY IN THE PERIOD DIFFERS THE ECMWF AND
GFS ARE IN GOOD GENERAL AGREEMENT ON POSITION AND MOVEMENT OF THE
SYSTEM. AT THE START OF THE PERIOD...A LOW CENTERED OVER THE GREAT
LAKES WITH AN ASSOCIATED WARM FRONT EXTENDING NORTH JUST SOUTH OF
JAMES BAY...A COLD FRONT EXTENDING SOUTH INTO EASTERN TEXAS. A
HIGH PRESSURE RIDGE BUILD NORTH ALONG THE EASTERN SEABOARD. THE
LOW WILL TRACK EAST INTO QUEBEC BY SUNDAY NIGHT. THE RIDGE WILL
RIDGE INTO THE NORTH ATLANTIC. BY MONDAY MORNING THE LOW WILL MOVE
INTO EASTERN QUEBEC. THE COLD FRONT WILL WEAKEN AS A NEW LOW
DEVELOPS WEST VIRGINIA. BY EARLY TUESDAY MORNING THE GFS MAINTAINS
THE LOW OVER WEST VIRGINIA AND EXTENDS THE WARM FRONT INTO
SOUTHERN QUEBEC. THE ECMWF MOVES THE LOW INTO THE EASTERN GREAT
LAKES REGION...SHOWING A WEAKLY DEVELOPED OCCLUSION...THE TRIPLE
POINT IN NORTHERN NEW YORK...COLD FRONT EXTENDING SOUTH THROUGH
THE CENTRAL PORTIONS OF THE ATLANTIC STATES...THE WARM FRONT
EXTENDING EAST THROUGH CAPE COD. BY TUESDAY EVENING THE GFS MOVES
THE LOW NORTHEAST TO NEW JERSEY...WITH THE WARM FRONT EXTENDING
NORTHEAST THROUGH CENTRAL MAINE. THE ECMWF DEVELOPS A NEW LOW OVER
SOUTHERN MAINE...MOVES THE COLD FRONT EAST INTO THE
ATLANTIC...WITH THE WARM FRONT EXTENDED ACROSS CENTRAL MAINE. BY
WEDNESDAY MORNING BOTH MODELS ARE INDICATING A LOW CENTERED OVER
MAINE. THE GFS MAINTAIN THE COLD FRONT EXTENDING SOUTHWEST ALONG
THE ATLANTIC COASTAL STATES. THE GFS COLD FRONT IS WELL EAST OF THE
COAST. HIGHER PRESSURE WILL START TO BUILD NORTH IN BEHIND THE
LOW. BY THE END OF THE PERIOD THE GFS BUILDS THE HIGH ACROSS THE
AREA...THE ECMWF MAINTAINS THE LOW OVER MAINE.
LOADED GMOS...WITH SOME HAND SMOOTHING. PLUS 15 PERCENT FOR GUST
OVER LAND 20 PERCENT OVER WATER. NAWAVE 4 FOR SEAS IN THE COASTAL
WATERS.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
NEAR TERM: MVFR CLGS THRU ERLY THIS EVE SHOULD TRANSITION TO VFR
OVRNGT...FIRST OVR DOWNEAST SITES LATE THIS EVE AND EVENTUALLY
ACROSS NRN TAF SITES BY WELL AFT MDNGT.
SHORT TERM: VFR CONDITIONS ARE EXPECTED THURSDAY NIGHT. SCATTERED SNOW
SHOWERS FRIDAY AFTERNOON COULD BRING BRIEF PERIODS OF MVFR MAINLY
TO KCAR/KPQI/KHUL WITH VFR EXPECTED KBGR/KBHB. VFR EXPECTED ALL
TERMINALS FRIDAY NIGHT AND SATURDAY.
&&
.MARINE...
NEAR TERM: TRANSITIONED THINGS TO SCA FOR SEAS OVERNIGHT INTO
THURSDAY AS WAVE HEIGHTS AFE EXPECTED TO STAY UP LONGER.
.PREVIOUS DISCUSSION...
BLENDED WW3 WV GUIDANCE TO PRIOR FCST AND WENT WITH A BLEND OF
12Z NAM AND GFS FOR WINDS.
SHORT TERM: WINDS/SEAS COULD APPROACH SCA LEVELS FRIDAY NIGHT.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM EST
THURSDAY FOR ANZ050-051.
&&
$$
NEAR TERM...HEWITT
AREA FORECAST DISCUSSION
NWS CARIBOU ME
610 PM EST WED NOV 30 2011
.SYNOPSIS...
LOW PRESSURE WILL LIFT WEST OF THE AREA TODAY PULLING A COLD FRONT
ACROSS THE REGION. HIGH PRESSURE WILL BUILD EAST TONIGHT...THEN
CROSS THE REGION THURSDAY. A WEAK DISTURBANCE WILL CROSS THE
REGION FRIDAY.
&&
.NEAR TERM /THROUGH THURSDAY/...
.UPDATE...
ADJUSTED THE POPS USING A BLEND OF THE NAM12 AND RUC THROUGH 06Z
W/THE RADAR SHOWING A LINE OF SHOWERS MOVING ACROSS THE NORTHERN
AND CENTRAL SECTIONS OF THE CWA. HRLY TEMPERATURES WERE ADJUSTED
UPWARD A FEW DEGREE USING THE LATEST LAMP GUIDANCE ALONG W/THE
WINDS.
WHATS LEFT OF STEADIER RN SHWRS IS WANING ACROSS ERN NB WHILE NEW
SHWRS ARE FORMING OVR NW ME AHEAD OF AN UPPER TROF AND SECONDARY
COLD APCHG FROM ERN QB. SHOWERS WILL BE POSSIBLE WELL INTO THE EVE
ACROSS NRN PTNS OF THE FA...POSSIBLY ENDING AS FLURRIES LATE TNGT.
MOST OF THE TEMP FALL OVRNGT WILL OCCUR LATE BEHIND THE SECONDARY
COLD FRONT... WHICH HAS THE GREATER IMPACT OF LLVL COLD ADVCN.
SKIES SHOULD CLR EVEN ACROSS NRN PTNS OF THE FA BEHIND THE UPPER
TROF VERY LATE TNGT INTO ERLY THU MORN...ALLOWING FOR MSLY SUNNY
SKIES AND SOMEWHAT CONDITIONS FOR THU. AFTER REACHING SIG COLDER...
BUT STILL ABV NORMAL OVRNGT LOW TEMPS DAYBREAK THU...HI TEMPS THU
WHICH WILL BE 20 TO 30 DEG F COOLER THAN TDY...FEELING BRISK IN
COMPARISON.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
A WEAK AREA OF HIGH PRESSURE WILL BUILD ACROSS THE REGION IN
ADVANCE OF A WEAK DISTURBANCE APPROACHING FROM THE WEST. MAINLY
CLEAR SKIES THURSDAY EVENING WILL GIVE WAY TO INCREASING CLOUDS
LATER THURSDAY NIGHT. A FAIRLY GOOD PERIOD OF RADIATIONAL COOLING
IS EXPECTED BEFORE CLOUDS INCREASE LATER THURSDAY NIGHT WITH LOWS
IN THE TEENS NORTH AND LOWER 20S DOWNEAST. EXPECT MOSTLY CLOUDY
SKIES ON FRIDAY WITH THE CHANCE FOR SNOW SHOWERS MAINLY ACROSS
NORTHERN AREAS AS THE SHORT WAVES MOVE EAST ACROSS THE REGION.
HIGH PRESSURE WILL BUILD IN FROM THE WEST FRIDAY NIGHT WITH
CLEARING SKIES. HIGH PRESSURE WILL SLIDE ACROSS THE REGION
SATURDAY WITH FAIR WEATHER AND SEASONABLY COOL TEMPERATURES
EXPECTED.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THOUGH THE INTENSITY OF A FRONTAL SYSTEM TRACKING ACROSS THE
CENTRAL UNITED STATES EARLY IN THE PERIOD DIFFERS THE ECMWF AND
GFS ARE IN GOOD GENERAL AGREEMENT ON POSITION AND MOVEMENT OF THE
SYSTEM. AT THE START OF THE PERIOD...A LOW CENTERED OVER THE GREAT
LAKES WITH AN ASSOCIATED WARM FRONT EXTENDING NORTH JUST SOUTH OF
JAMES BAY...A COLD FRONT EXTENDING SOUTH INTO EASTERN TEXAS. A
HIGH PRESSURE RIDGE BUILD NORTH ALONG THE EASTERN SEABOARD. THE
LOW WILL TRACK EAST INTO QUEBEC BY SUNDAY NIGHT. THE RIDGE WILL
RIDGE INTO THE NORTH ATLANTIC. BY MONDAY MORNING THE LOW WILL MOVE
INTO EASTERN QUEBEC. THE COLD FRONT WILL WEAKEN AS A NEW LOW
DEVELOPS WEST VIRGINIA. BY EARLY TUESDAY MORNING THE GFS MAINTAINS
THE LOW OVER WEST VIRGINIA AND EXTENDS THE WARM FRONT INTO
SOUTHERN QUEBEC. THE ECMWF MOVES THE LOW INTO THE EASTERN GREAT
LAKES REGION...SHOWING A WEAKLY DEVELOPED OCCLUSION...THE TRIPLE
POINT IN NORTHERN NEW YORK...COLD FRONT EXTENDING SOUTH THROUGH
THE CENTRAL PORTIONS OF THE ATLANTIC STATES...THE WARM FRONT
EXTENDING EAST THROUGH CAPE COD. BY TUESDAY EVENING THE GFS MOVES
THE LOW NORTHEAST TO NEW JERSEY...WITH THE WARM FRONT EXTENDING
NORTHEAST THROUGH CENTRAL MAINE. THE ECMWF DEVELOPS A NEW LOW OVER
SOUTHERN MAINE...MOVES THE COLD FRONT EAST INTO THE
ATLANTIC...WITH THE WARM FRONT EXTENDED ACROSS CENTRAL MAINE. BY
WEDNESDAY MORNING BOTH MODELS ARE INDICATING A LOW CENTERED OVER
MAINE. THE GFS MAINTAIN THE COLD FRONT EXTENDING SOUTHWEST ALONG
THE ATLANTIC COASTAL STATES. THE GFS COLD FRONT IS WELL EAST OF THE
COAST. HIGHER PRESSURE WILL START TO BUILD NORTH IN BEHIND THE
LOW. BY THE END OF THE PERIOD THE GFS BUILDS THE HIGH ACROSS THE
AREA...THE ECMWF MAINTAINS THE LOW OVER MAINE.
LOADED GMOS...WITH SOME HAND SMOOTHING. PLUS 15 PERCENT FOR GUST
OVER LAND 20 PERCENT OVER WATER. NAWAVE 4 FOR SEAS IN THE COASTAL
WATERS.
&&
.AVIATION /23Z WEDNESDAY THROUGH MONDAY/...
NEAR TERM: MVFR CLGS THRU ERLY THIS EVE SHOULD TRANSITION TO VFR
OVRNGT...FIRST OVR DOWNEAST SITES LATE THIS EVE AND EVENTUALLY
ACROSS NRN TAF SITES BY WELL AFT MDNGT.
SHORT TERM: VFR CONDITIONS ARE EXPECTED THURSDAY NIGHT. SCATTERED SNOW
SHOWERS FRIDAY AFTERNOON COULD BRING BRIEF PERIODS OF MVFR MAINLY
TO KCAR/KPQI/KHUL WITH VFR EXPECTED KBGR/KBHB. VFR EXPECTED ALL
TERMINALS FRIDAY NIGHT AND SATURDAY.
&&
.MARINE...
NEAR TERM: WILL CONT SCA FOR OUTER MZS050-051 TIL 05Z AND THE SCA
FOR HAZ SEAS FOR INNER HARBOR MZ052 TIL 22Z BASED ON LATEST
UPDATE OF WINDS AND SEAS THRU TNGT. SCA FOR HAZ SEAS WILL LIKELY
NEED TO REPLACE THE SCA FOR OUTER MZS AFT 05Z...POSSIBLY LASTING
WELL INTO THU BEFORE SUBSIDING BLO 5 FT. OTHERWISE...BLENDED WW3
WV GUIDANCE TO PRIOR FCST AND WENT WITH A BLEND OF 12Z NAM AND
GFS FOR WINDS.
SHORT TERM: WINDS/SEAS COULD APPROACH SCA LEVELS FRIDAY NIGHT.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR ANZ050-051.
&&
$$
NEAR TERM...HEWITT/VJN
SHORT TERM...DUDA
LONG TERM...NORTON
AVIATION...HEWITT/VJN
MARINE...HEWITT/VJN/DUDA
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
941 AM EST TUE NOV 29 2011
.SYNOPSIS...
AS A COLD FRONT MOVES THROUGH LATER TODAY...RAIN WILL DIMINISH AND
COLDER WEATHER WILL ARRIVE. SNOW SHOWERS ARE POSSIBLE TONIGHT
INTO WEDNESDAY. DRY WEATHER IS SLATED FOR THE LATTER PART OF THE
WEEK UNDER SEASONAL TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
PLUME OF MOISTURE ASSOCIATED WITH THE WARM CONVEYOR BELT EXTENDS ALL
ALL THE WAY TO THE ATLANTIC...WHICH IS BRINGING RAIN /AT TIMES
MODERATE/ TO LOCATIONS EAST OF THE OHIO RIVER. AS THE UPPER LEVEL
CYCLONE CONTINUES ITS NE MOVEMENT...THE AXIS OF RAIN WILL SHIFT NE
AS WELL THIS AFTERNOON. QPF AMOUNTS WILL BE AROUND 0.50 INCHES
WITH THIS BAND...BUT STILL DO NOT FEEL THIS WILL YIELD ANY HIGH
WATER.
WITH THE LOW EXPECTED TO TRACK ACROSS EASTERN OHIO UP TO LAKE
ERIE...DRY SLOT WILL PASS DURING THE EVENING...LEAVING EASTERN
OHIO AND NORTHERN WV PANHANDLE DRY FOR A PERIOD OF TIME.
HOWEVER...MODELS ARE IN AGREEMENT THAT ANOTHER PIECE OF ENERGY
WILL RIDE UP THE RIDGES DURING THE EVENING HOURS. ALSO CAN NOT
RULE OUT A PERIOD OF DRIZZLE AS THE MID AND UPPER MOISTURE PULL
AWAY.
TEMPERATURES ACROSS THE RIDGES WILL BE CRITICAL DURING THIS TIME
PERIOD: IF TEMPS DROP LOW ENOUGH...THERE IS THE POTENTIAL TO DROP
A QUICK 1-3 INCHES OF SNOW DURING THIS PERIOD OF TIME.
CURRENT FORECAST ANTICIPATES THAT THIS PRECIP WILL FALL AS RAIN
DURING THE EVENING. AFTER MIDNIGHT...MORE MOISTURE WILL BEGIN TO
MOVE IN FROM THE WEST...ALLOWING FOR SOME SHOWERS TO RETURN TO THE
ENTIRE FORECAST AREA. ALONG THE RIDGES...ABOUT AN INCH OF SNOW IS
EXPECTED AFTER MIDNIGHT. OUTSIDE OF THE RIDGES...A MIX OR
CHANGEOVER TO SNOW CERTAINLY CANNOT BE RULED OUT...BUT
TEMPERATURES ARE EXPECTED TO ONLY DROP TO THE MID 30S
OVERNIGHT...LIMITING ACCUMULATION.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
LOW PRESSURE CENTER SHOULD BE NORTH OF LAKE ONTARIO BY WEDNESDAY
MORNING...AND THE CENTER WILL CONTINUE ITS TREK TO THE NORTHEAST.
WINDS SHOULD BECOME FAVORABLE FOR SOME LAKE EFFECT/UPSLOPE FLOW FOR
SEVERAL HOURS ON WEDNESDAY...AND WITH REMAINS OF DEFORMATION ZONE
MOVING TO THE EAST...HAVE INCREASED POPS ACROSS MOST LOCATIONS
DURING THE DAY. HAVE ALSO BUMPED UP POPS A BIT WEDNESDAY NIGHT FOR
THE RIDGES AS UPSLOPE WINDS SQUEEZE REMAINING MOISTURE OUT. WITH
MUCH COLDER TEMPERATURES WEDNESDAY...REMAINS TO BE SEEN IF SHOWERS
WILL REMAIN SNOW...OR CHANGEOVER TO RAIN. HIGH PRESSURE WILL MOVE
INTO THE REGION BY THURSDAY...ALLOWING FOR DRY CONDITIONS THAT DAY
INTO FRIDAY. ALTHOUGH THERE WILL BE SOME SLIGHT MODERATION IN
TEMPS...HIGHS WILL REMAIN A COUPLE OF DEGREES BELOW NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS HAVE BEEN CONSISTENT WITH A WEAK COLD FRONT CLIPPING THE
AREA LATE FRIDAY/FRIDAY NIGHT. WITH LIMITED MOISTURE...WILL USE
LOW END CHANCE POPS. DRY AND CHILLY CONDITIONS ARE EXPECTED FOR
SATURDAY...WITH A SMALL CHANCE OF PRECIP COMING IN FOR LATE SUNDAY
AND MONDAY.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
BLEND OF RECENT SURFACE AND RADAR DATA ALONG WITH HRRR AND NAM MODEL
OUTPUT SHOW COLD FRONTAL BAND OF RAIN MOVING NORTHEASTWARD THROUGH
THE UPPER OHIO VALLEY THROUGH EARLY AFTERNOON.
THE MAIN AVIATION CONCERN WILL BE THE WIND. WINDS FROM 2 KFT AGL UP
WILL BE 40 KTS, WITH RAIN NOW OCCURRING, THE FAST WINDS CAN MIX
TO THE SURFACE TO CAUSE GUSTS OF 25-30 KTS, AS EVIDENCED BY RECENT
SURFACE DATA OVER THE MOUNTAINS, FOR EXAMPLE KEKN, K2G4, KJST, AND
KDUJ.
WITHIN THE FRONTAL RAIN BAND, FLIGHT CONDITIONS WILL DETERIORATE TO
MVFR THIS MORNING WITH SHORT-LIVED IFR POSSIBLE IN HEAVIER RAINFALL.
WITH PASSAGE OF THE COLD FRONT TOWARD MIDDAY, SURFACE WINDS WILL
SHIFT INTO THE SOUTHWEST WITH GUSTS TO 20-25 KTS. POST FRONTAL
CONDITIONS THIS AFTERNOON AND TONIGHT WILL BE MAINLY MVFR IN
INTERMITTENT SHOWERS. THERE CAN BE A DRY SLOT WITH VFR CONDITIONS
LATE AFTERNOON INTO EVENING, FOLLOWED BY RENEWED SHOWERS TONIGHT DUE
TO TROWAL DYNAMICS.
SURFACE TEMPERATURES WILL DROP INTO THE 30S, BUT NAM MODEL PROFILES
SUGGEST CLOUDS MAY BE TOO SHALLOW, WEST OF THE MOUNTAINS, TO PRODUCE
A CHANGE TO SNOW SHOWERS AS CLOUD TOP TEMPERATURES CAN BE WARMER
THAN THE M10C NEEDED FOR ICE NUCLEI INITIATION. NEAR THE MOUNTAINS,
CLOUDS CAN BE TALLER AND HENCE HAVE COLDER CLOUD TOPS MAKING SNOW
FORMATION POSSIBLE.
OUTLOOK...WEDNESDAY THROUGH SATURDAY....
NO WIDESPREAD IFR WEATHER IS PREDICTED.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
707 AM EST TUE NOV 29 2011
.SYNOPSIS...
AS A COLD FRONT MOVES THROUGH TODAY...RAIN WILL DIMINISH AND
COLDER TEMPERATURES WILL ARRIVE. SNOW SHOWERS ARE POSSIBLE TONIGHT
INTO WEDNESDAY. DRY WEATHER IS SLATED FOR THE LATTER PART OF THE
WEEK UNDER SEASONAL TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
LOW PRESSURE CURRENTLY OVER SOUTHERN OHIO IS PROJECTED TO MOVE TO
THE NORTHEAST DURING THE DAY. ASSOCIATED COLD FRONT CURRENTLY WRAPS
TO THE SOUTHEAST FROM THE LOW...WRAPPING BACK INTO THE CAROLINAS.
RAIN WILL OVERSPREAD THE REGION FROM SOUTH TO NORTH AS THE LOW
APPROACHES...WITH THE HEAVIEST RAINFALL OCCURRING AS THE FRONT MOVES
THROUGH LATE MORNING/EARLY AFTERNOON.
BASED ON RECENT NAM MODEL OUTPUT AND UPPER AIR DATA, EXPECT
SURFACE WINDS TO GUST TO 25-30 MPH AT TIMES.
TEMPERATURES REMAIN QUITE WARM IN ADVANCE OF THE FRONT...WITH
OVERNIGHT TEMPERATURES WELL ABOVE CLIMATOLOGICAL HIGH TEMPERATURES
FOR LATE NOVEMBER. ALTHOUGH SOME BRIEF WARMING IS POSSIBLE THIS
MORNING...TEMPERATURES WILL FALL DURING THE DAY AS THE COLD FRONT
PASSES.
WITH THE LOW EXPECTED TO TRACK ACROSS EASTERN OHIO UP TO LAKE
ERIE...DRY SLOT COULD THEN PASS THROUGH DURING THE EVENING
HOURS...LEAVING EASTERN OHIO AND NORTHERN WV PANHANDLE DRY FOR A
PERIOD OF TIME. HOWEVER...MODELS ARE IN AGREEMENT THAT ANOTHER
PIECE OF ENERGY WILL RIDE UP THE RIDGES DURING THE EVENING HOURS.
TEMPERATURES ACROSS THE RIDGES WILL BE CRITICAL DURING THIS TIME
PERIOD: IF TEMPS DROP LOW ENOUGH...THERE IS THE POTENTIAL TO DROP
A QUICK 1-3 INCHES OF SNOW DURING THIS PERIOD OF TIME.
CURRENT FORECAST ANTICIPATES THAT THIS PRECIP WILL FALL AS RAIN
DURING THE EVENING. AFTER MIDNIGHT...MORE MOISTURE WILL BEGIN TO
MOVE IN FROM THE WEST...ALLOWING FOR SOME SHOWERS TO RETURN TO THE
ENTIRE FORECAST AREA. ALONG THE RIDGES...ABOUT AN INCH OF SNOW IS
EXPECTED AFTER MIDNIGHT. OUTSIDE OF THE RIDGES...A MIX OR
CHANGEOVER TO SNOW CERTAINLY CANNOT BE RULED OUT...BUT
TEMPERATURES ARE EXPECTED TO ONLY DROP TO THE MID 30S
OVERNIGHT...LIMITING ACCUMULATION.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
LOW PRESSURE CENTER SHOULD BE NORTH OF LAKE ONTARIO BY WEDNESDAY
MORNING...AND THE CENTER WILL CONTINUE ITS TREK TO THE NORTHEAST.
WINDS SHOULD BECOME FAVORABLE FOR SOME LAKE EFFECT/UPSLOPE FLOW FOR
SEVERAL HOURS ON WEDNESDAY...AND WITH REMAINS OF DEFORMATION ZONE
MOVING TO THE EAST...HAVE INCREASED POPS ACROSS MOST LOCATIONS
DURING THE DAY. HAVE ALSO BUMPED UP POPS A BIT WEDNESDAY NIGHT FOR
THE RIDGES AS UPSLOPE WINDS SQUEEZE REMAINING MOISTURE OUT. WITH
MUCH COLDER TEMPERATURES WEDNESDAY...REMAINS TO BE SEEN IF SHOWERS
WILL REMAIN SNOW...OR CHANGEOVER TO RAIN. HIGH PRESSURE WILL MOVE
INTO THE REGION BY THURSDAY...ALLOWING FOR DRY CONDITIONS THAT DAY
INTO FRIDAY. ALTHOUGH THERE WILL BE SOME SLIGHT MODERATION IN
TEMPS...HIGHS WILL REMAIN A COUPLE OF DEGREES BELOW NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS HAVE BEEN CONSISTENT WITH A WEAK COLD FRONT CLIPPING THE
AREA LATE FRIDAY/FRIDAY NIGHT. WITH LIMITED MOISTURE...WILL USE
LOW END CHANCE POPS. DRY AND CHILLY CONDITIONS ARE EXPECTED FOR
SATURDAY...WITH A SMALL CHANCE OF PRECIP COMING IN FOR LATE SUNDAY
AND MONDAY.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
BLEND OF RECENT SURFACE AND RADAR DATA ALONG WITH HRRR AND NAM MODEL
OUTPUT SHOW COLD FRONTAL BAND OF RAIN MOVING NORTHEASTWARD THROUGH
THE UPPER OHIO VALLEY THROUGH EARLY AFTERNOON.
THE MAIN AVIATION CONCERN WILL BE THE WIND. WINDS FROM 2 KFT AGL UP
WILL BE 40 KTS, WITH RAIN NOW OCCURRING, THE FAST WINDS CAN MIX
TO THE SURFACE TO CAUSE GUSTS OF 25-30 KTS, AS EVIDENCED BY RECENT
SURFACE DATA OVER THE MOUNTAINS, FOR EXAMPLE KEKN, K2G4, KJST, AND
KDUJ.
WITHIN THE FRONTAL RAIN BAND, FLIGHT CONDITIONS WILL DETERIORATE TO
MVFR THIS MORNING WITH SHORT-LIVED IFR POSSIBLE IN HEAVIER RAINFALL.
WITH PASSAGE OF THE COLD FRONT TOWARD MIDDAY, SURFACE WINDS WILL
SHIFT INTO THE SOUTHWEST WITH GUSTS TO 20-25 KTS. POST FRONTAL
CONDITIONS THIS AFTERNOON AND TONIGHT WILL BE MAINLY MVFR IN
INTERMITTENT SHOWERS. THERE CAN BE A DRY SLOT WITH VFR CONDITIONS
LATE AFTERNOON INTO EVENING, FOLLOWED BY RENEWED SHOWERS TONIGHT DUE
TO TROWAL DYNAMICS.
SURFACE TEMPERATURES WILL DROP INTO THE 30S, BUT NAM MODEL PROFILES
SUGGEST CLOUDS MAY BE TOO SHALLOW, WEST OF THE MOUNTAINS, TO PRODUCE
A CHANGE TO SNOW SHOWERS AS CLOUD TOP TEMPERATURES CAN BE WARMER
THAN THE M10C NEEDED FOR ICE NUCLEI INITIATION. NEAR THE MOUNTAINS,
CLOUDS CAN BE TALLER AND HENCE HAVE COLDER CLOUD TOPS MAKING SNOW
FORMATION POSSIBLE.
OUTLOOK...WEDNESDAY THROUGH SATURDAY....
CONTINUED POST SYSTEM WRAP-AROUND SHOWERS MAY CAUSE ADDITIONAL
PERIODS OF MAINLY MVFR RESTRICTIONS INTO WEDNESDAY NIGHT. THEN
MAINLY VFR UNDER HIGH PRESSURE THURSDAY INTO SATURDAY. ALBEIT THERE
IS A SMALL CHANCE OF SHOWERS WITH RESTRICTIONS NORTH FROM A PASSING
GREAT LAKES COLD FRONT FRIDAY NIGHT.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
438 AM EST TUE NOV 29 2011
.SYNOPSIS...
AS A COLD FRONT MOVES THROUGH TODAY...RAIN WILL DIMINISH AND
COLDER TEMPERATURES WILL ARRIVE. SNOW SHOWERS ARE POSSIBLE TONIGHT
INTO WEDNESDAY. DRY WEATHER IS SLATED FOR THE LATTER PART OF THE
WEEK UNDER SEASONAL TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
LOW PRESSURE CURRENTLY OVER SOUTHERN OHIO IS PROJECTED TO MOVE TO
THE NORTHEAST DURING THE DAY. ASSOCIATED COLD FRONT CURRENTLY WRAPS
TO THE SOUTHEAST FROM THE LOW...WRAPPING BACK INTO THE CAROLINAS.
RAIN WILL OVERSPREAD THE REGION FROM SOUTH TO NORTH AS THE LOW
APPROACHES...WITH THE HEAVIEST RAINFALL OCCURRING AS THE FRONT MOVES
THROUGH LATE MORNING/EARLY AFTERNOON. TEMPERATURES REMAIN QUITE WARM
IN ADVANCE OF THE FRONT...WITH OVERNIGHT TEMPERATURES WELL ABOVE
CLIMATOLOGICAL HIGH TEMPERATURES FOR LATE NOVEMBER. ALTHOUGH SOME
BRIEF WARMING IS POSSIBLE THIS MORNING...TEMPERATURES WILL FALL
DURING THE DAY AS THE COLD FRONT PASSES. WITH THE LOW EXPECTED TO
TRACK ACROSS EASTERN OHIO UP TO LAKE ERIE...DRY SLOT COULD THEN PASS
THROUGH DURING THE EVENING HOURS...LEAVING EASTERN OHIO AND NORTHERN
WV PANHANDLE DRY FOR A PERIOD OF TIME. HOWEVER...MODELS ARE IN
AGREEMENT THAT ANOTHER PIECE OF ENERGY WILL RIDE UP THE RIDGES
DURING THE EVENING HOURS. TEMPERATURES ACROSS THE RIDGES WILL BE
CRITICAL DURING THIS TIME PERIOD: IF TEMPS DROP LOW ENOUGH...THERE
IS THE POTENTIAL TO DROP A QUICK 1-3 INCHES OF SNOW DURING THIS
PERIOD OF TIME. CURRENT FORECAST ANTICIPATES THAT THIS PRECIP WILL
FALL AS RAIN DURING THE EVENING. AFTER MIDNIGHT...MORE MOISTURE WILL
BEGIN TO MOVE IN FROM THE WEST...ALLOWING FOR SOME SHOWERS TO RETURN
TO THE ENTIRE FORECAST AREA. ALONG THE RIDGES...ABOUT AN INCH OF
SNOW IS EXPECTED AFTER MIDNIGHT. OUTSIDE OF THE RIDGES...A MIX OR
CHANGEOVER TO SNOW CERTAINLY CANNOT BE RULED OUT...BUT TEMPERATURES
ARE EXPECTED TO ONLY DROP TO THE MID 30S OVERNIGHT...LIMITING
ACCUMULATION.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
LOW PRESSURE CENTER SHOULD BE NORTH OF LAKE ONTARIO BY WEDNESDAY
MORNING...AND THE CENTER WILL CONTINUE ITS TREK TO THE NORTHEAST.
WINDS SHOULD BECOME FAVORABLE FOR SOME LAKE EFFECT/UPSLOPE FLOW FOR
SEVERAL HOURS ON WEDNESDAY...AND WITH REMAINS OF DEFORMATION ZONE
MOVING TO THE EAST...HAVE INCREASED POPS ACROSS MOST LOCATIONS
DURING THE DAY. HAVE ALSO BUMPED UP POPS A BIT WEDNESDAY NIGHT FOR
THE RIDGES AS UPSLOPE WINDS SQUEEZE REMAINING MOISTURE OUT. WITH
MUCH COLDER TEMPERATURES WEDNESDAY...REMAINS TO BE SEEN IF SHOWERS
WILL REMAIN SNOW...OR CHANGEOVER TO RAIN. HIGH PRESSURE WILL MOVE
INTO THE REGION BY THURSDAY...ALLOWING FOR DRY CONDITIONS THAT DAY
INTO FRIDAY. ALTHOUGH THERE WILL BE SOME SLIGHT MODERATION IN
TEMPS...HIGHS WILL REMAIN A COUPLE OF DEGREES BELOW NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS HAVE BEEN CONSISTENT WITH A WEAK COLD FRONT CLIPPING THE
AREA LATE FRIDAY/FRIDAY NIGHT. WITH LIMITED MOISTURE...WILL USE
LOW END CHANCE POPS. DRY AND CHILLY CONDITIONS ARE EXPECTED FOR
SATURDAY...WITH A SMALL CHANCE OF PRECIP COMING IN FOR LATE SUNDAY
AND MONDAY.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
BLEND OF RECENT SURFACE AND RADAR DATA ALONG WITH HRRR AND NAM MODEL
OUTPUT SHOW COLD FRONTAL BAND OF RAIN MOVING NORTHEASTWARD THROUGH
THE UPPER OHIO VALLEY THROUGH EARLY AFTERNOON.
INITIAL AVIATION CONCERN WILL BE THE WIND. WINDS FROM 2 KFT AGL UP
WILL BE SOUTHEAST AT 40 KTS, WHICH CAN PRODUCE LOW LEVEL WIND SHEAR
AS LONG AS SURFACE WINDS REMAIN LESS THAN 15 KTS. HOWEVER, WITH THE
RAIN BAND ONSET, THE FAST WINDS CAN MIX TO THE SURFACE TO CAUSE
GUSTS OF 25-30 KTS, AS EVIDENCED BY RECENT SURFACE DATA OVER THE
MOUNTAINS, FOR EXAMPLE KEKN, K2G4, KJST, AND KDUJ.
WITHIN THE FRONTAL RAIN BAND, FLIGHT CONDITIONS WILL DETERIORATE TO
MVFR THIS MORNING WITH SHORT-LIVED IFR POSSIBLE IN HEAVIER RAINFALL.
WITH PASSAGE OF THE COLD FRONT TOWARD MIDDAY, SURFACE WINDS WILL
SHIFT INTO THE SOUTHWEST WITH GUSTS TO 20-25 KTS. POST FRONTAL
CONDITIONS THIS AFTERNOON AND TONIGHT WILL BE MAINLY MVFR IN
INTERMITTENT SHOWERS. THERE CAN BE A DRY SLOT WITH VFR CONDITIONS
LATE AFTERNOON INTO EVENING, FOLLOWED BY RENEWED SHOWERS TONIGHT DUE
TO TROWAL DYNAMICS.
SURFACE TEMPERATURES WILL DROP INTO THE 30S, BUT NAM MODEL PROFILES
SUGGEST CLOUDS MAY BE TOO SHALLOW, WEST OF THE MOUNTAINS, TO PRODUCE
A CHANGE TO SNOW SHOWERS AS CLOUD TOP TEMPERATURES CAN BE WARMER
THAN THE M10C NEEDED FOR ICE NUCLEI INITIATION. NEAR THE MOUNTAINS,
CLOUDS CAN BE TALLER AND HENCE HAVE COLDER CLOUD TOPS MAKING SNOW
FORMATION POSSIBLE.
OUTLOOK...WEDNESDAY THROUGH SATURDAY....
CONTINUED POST SYSTEM WRAP-AROUND SHOWERS MAY CAUSE ADDITIONAL
PERIODS OF MAINLY MVFR RESTRICTIONS INTO WEDNESDAY NIGHT. THEN
MAINLY VFR UNDER HIGH PRESSURE THURSDAY INTO SATURDAY. ALBEIT THERE
IS A SMALL CHANCE OF SHOWERS WITH RESTRICTIONS NORTH FROM A PASSING
GREAT LAKES COLD FRONT FRIDAY NIGHT.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
318 AM EST TUE NOV 29 2011
.SYNOPSIS...
AS A COLD FRONT MOVES THROUGH TODAY...RAIN WILL DIMINISH AND
COLDER TEMPERATURES WILL ARRIVE. SNOW SHOWERS ARE POSSIBLE TONIGHT
INTO WEDNESDAY. DRY WEATHER IS SLATED FOR THE LATTER PART OF THE
WEEK UNDER SEASONAL TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
LOW PRESSURE CURRENTLY OVER SOUTHERN OHIO IS PROJECTED TO MOVE TO
THE NORTHEAST DURING THE DAY. ASSOCIATED COLD FRONT CURRENTLY WRAPS
TO THE SOUTHEAST FROM THE LOW...WRAPPING BACK INTO THE CAROLINAS.
RAIN WILL OVERSPREAD THE REGION FROM SOUTH TO NORTH AS THE LOW
APPROACHES...WITH THE HEAVIEST RAINFALL OCCURRING AS THE FRONT MOVES
THROUGH LATE MORNING/EARLY AFTERNOON. TEMPERATURES REMAIN QUITE WARM
IN ADVANCE OF THE FRONT...WITH OVERNIGHT TEMPERATURES WELL ABOVE
CLIMATOLOGICAL HIGH TEMPERATURES FOR LATE NOVEMBER. ALTHOUGH SOME
BRIEF WARMING IS POSSIBLE THIS MORNING...TEMPERATURES WILL FALL
DURING THE DAY AS THE COLD FRONT PASSES. WITH THE LOW EXPECTED TO
TRACK ACROSS EASTERN OHIO UP TO LAKE ERIE...DRY SLOT COULD THEN PASS
THROUGH DURING THE EVENING HOURS...LEAVING EASTERN OHIO AND NORTHERN
WV PANHANDLE DRY FOR A PERIOD OF TIME. HOWEVER...MODELS ARE IN
AGREEMENT THAT ANOTHER PIECE OF ENERGY WILL RIDE UP THE RIDGES
DURING THE EVENING HOURS. TEMPERATURES ACROSS THE RIDGES WILL BE
CRITICAL DURING THIS TIME PERIOD: IF TEMPS DROP LOW ENOUGH...THERE
IS THE POTENTIAL TO DROP A QUICK 1-3 INCHES OF SNOW DURING THIS
PERIOD OF TIME. CURRENT FORECAST ANTICIPATES THAT THIS PRECIP WILL
FALL AS RAIN DURING THE EVENING. AFTER MIDNIGHT...MORE MOISTURE WILL
BEGIN TO MOVE IN FROM THE WEST...ALLOWING FOR SOME SHOWERS TO RETURN
TO THE ENTIRE FORECAST AREA. ALONG THE RIDGES...ABOUT AN INCH OF
SNOW IS EXPECTED AFTER MIDNIGHT. OUTSIDE OF THE RIDGES...A MIX OR
CHANGEOVER TO SNOW CERTAINLY CANNOT BE RULED OUT...BUT TEMPERATURES
ARE EXPECTED TO ONLY DROP TO THE MID 30S OVERNIGHT...LIMITING
ACCUMULATION.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
LOW PRESSURE CENTER SHOULD BE NORTH OF LAKE ONTARIO BY WEDNESDAY
MORNING...AND THE CENTER WILL CONTINUE ITS TREK TO THE NORTHEAST.
WINDS SHOULD BECOME FAVORABLE FOR SOME LAKE EFFECT/UPSLOPE FLOW FOR
SEVERAL HOURS ON WEDNESDAY...AND WITH REMAINS OF DEFORMATION ZONE
MOVING TO THE EAST...HAVE INCREASED POPS ACROSS MOST LOCATIONS
DURING THE DAY. HAVE ALSO BUMPED UP POPS A BIT WEDNESDAY NIGHT FOR
THE RIDGES AS UPSLOPE WINDS SQUEEZE REMAINING MOISTURE OUT. WITH
MUCH COLDER TEMPERATURES WEDNESDAY...REMAINS TO BE SEEN IF SHOWERS
WILL REMAIN SNOW...OR CHANGEOVER TO RAIN. HIGH PRESSURE WILL MOVE
INTO THE REGION BY THURSDAY...ALLOWING FOR DRY CONDITIONS THAT DAY
INTO FRIDAY. ALTHOUGH THERE WILL BE SOME SLIGHT MODERATION IN
TEMPS...HIGHS WILL REMAIN A COUPLE OF DEGREES BELOW NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS HAVE BEEN CONSISTENT WITH A WEAK COLD FRONT CLIPPING THE
AREA LATE FRIDAY/FRIDAY NIGHT. WITH LIMITED MOISTURE...WILL USE
LOW END CHANCE POPS. DRY AND CHILLY CONDITIONS ARE EXPECTED FOR
SATURDAY...WITH A SMALL CHANCE OF PRECIP COMING IN FOR LATE SUNDAY
AND MONDAY.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
BLEND OF RECENT SURFACE AND RADAR DATA ALONG WITH HRRR AND NAM MODEL
OUTPUT SHOW COLD FRONTAL BAND OF RAIN MOVING NORTHEASTWARD THROUGH
THE UPPER OHIO VALLEY THIS MORNING INTO EARLY AFTERNOON.
INITIAL AVIATION CONCERN WILL BE THE WIND. SURFACE WINDS WILL BE
EAST NEAR 10 KTS, WHILE WINDS FROM 2 KFT AGL UP WILL BE SOUTHEAST AT
40 KTS, WHICH CAN PRODUCE LOW LEVEL WIND SHEAR. JUST PRIOR TO THE
RAIN BAND ONSET, THE FAST WINDS CAN MIX TO THE SURFACE TO CAUSE
GUSTS OF 25-30 KTS, AS EVIDENCED BY RECENT SURFACE DATA OVER THE
MOUNTAINS.
WITHIN THE FRONTAL RAIN BAND, FLIGHT CONDITIONS WILL DETERIORATE TO
MVFR WITH SHORT-LIVED IFR POSSIBLE IN HEAVIER RAINFALL.
WITH PASSAGE OF THE COLD FRONT, SURFACE WINDS WILL SHIFT INTO THE
SOUTHWEST WITH GUSTS TO 20-25 KTS. POST FRONTAL CONDITIONS THIS
AFTERNOON AND TONIGHT WILL BE MAINLY MVFR IN INTERMITTENT SHOWERS.
THERE CAN BE A DRY SLOT WITH VFR CONDITIONS LATE AFTERNOON INTO
EVENING, FOLLOWED BY RENEWED SHOWERS TONIGHT DUE TO WRAP AROUND
DYNAMICS.
SURFACE TEMPERATURES WILL DROP INTO THE 30S, BUT NAM MODEL PROFILES
SUGGEST CLOUDS MAY BE TOO SHALLOW TO PRODUCE A CHANGE TO SNOW
SHOWERS AS CLOUD TOP TEMPERATURES CAN BE WARMER THAN THE M10C NEEDED
FOR ICE NUCLEI INITIATION.
OUTLOOK...WEDNESDAY THROUGH SATURDAY....
CONTINUED POST SYSTEM WRAP AROUND SHOWERS MAY CAUSE ADDITIONAL
PERIODS OF MAINLY MVFR RESTRICTIONS INTO WEDNESDAY NIGHT. THEN
MAINLY VFR UNDER HIGH PRESSURE THURSDAY INTO SATURDAY. ALBEIT
THERE IS A SMALL CHANCE OF SHOWERS WITH RESTRICTIONS NORTH FROM A
PASSING GREAT LAKES COLD FRONT FRIDAY NIGHT.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
101 AM EST TUE NOV 29 2011
.SYNOPSIS...
A SLOW MOVING LOW PRESSURE SYSTEM WILL BRING OCCASIONAL RAIN
THROUGH TUESDAY. COOLER WEATHER IN ITS WAKE WILL TURN RAIN
SHOWERS TO SNOW SHOWERS BY WEDNESDAY. DRY WEATHER IS SLATED FOR
THE LATTER PART OF THE WEEK UNDER SEASONAL TEMPERATURES.
&&
.NEAR TERM /THROUGH TODAY/...
06Z UPDATE: SOME MINOR TWEAKS MADE TO PREVIOUS FORECAST. PRIMARY
CHANGE WAS TO BUMP UP POPS ACROSS EASTERN OHIO WHERE STEADIEST
RAIN IS OCCURRING...AND TO TIGHTEN GRADIENT ALONG NORTHEASTERN
SHIELD OF PRECIP ACROSS NORTHWESTERN PA WHERE LITTLE RAIN HAS
FALLEN SO FAR. ALSO BUMPED UP WIND GUSTS ALONG THE RIDGES WHERE
SOUTHEAST WINDS ARE FAVORABLE FOR DOWNSLOPING. THERE HAVE BEEN A
FEW GUSTS TO 25-30 KTS ACROSS WV/MD RIDGES...AND EXPECT THAT THIS
SHOULD MAKE SOME NORTHWARD PROGRESS OVERNIGHT.
03Z UPDATE: NO BIG CHANGES TO THE ONGOING FORECAST. DRY WEATHER
CONTINUES FOR A FEW MORE HOURS OVER WRN PA AND NRN WV. WITH THE
WINDS PICKING UP...SO HAVE THE TEMPS. MGW HAS CLIMBED INTO THE MID
60S...WHILE OTHER LOCATIONS IN THE FAVORED DOWNSLOPE AREAS HAVE
ALSO ROSE. TWEAKED TEMPS TO ACCOUNT FOR LATEST TRENDS...OTHERWISE
PREVIOUS DISCUSSION FOLLOWS.
.PREVIOUS DISCUSSION...
HIGHEST CONFIDENCE FORECAST RESIDES IN EAST CENTRAL
OHIO WHERE STEADY LIGHT RAIN SHALL PERSIST THROUGH THE BALANCE OF
THE NIGHT. DUE NOT FORESEE MUCH CHANGE IN TEMPERATURES OVERNIGHT
DUE TO THE CLOUDS AND INCREASING WIND.
A SHORT PERIOD /3-6HRS/ OF LIGHT TO MODERATE RAINFALL SHALL OCCUR
FROM AFTER DAWN TUESDAY S OF THE MASON DIXON LINE TO MID AFTERNOON
ACROSS I-80 COMMUNITIES. TOTAL RAINFALL AMOUNTS ARE PROJECTED TO BE
AROUND 3/4" OF AN INCH...SAVE FOR ZZV AREA AND EASTERN PORTIONS OF
GARRETT AND TUCKER WHERE VALUES COULD BE A TENTH OR TWO HIGHER.
WINDS WILL PICK UP FROM THE SE TONIGHT OVER THE RIDGES S AND E OF
PIT. GUSTS COULD ECLIPSE 30 MPH.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
SHOWERS WILL DECREASE IN COVERAGE TUESDAY NIGHT BECOMING SCATTERED
BY WEDNESDAY. FORECAST POSITION OF OCCLUDED SURFACE FRONT...TRACK
OF LOW PRESSURE...AND MID LEVEL DRY PUNCH SHOULD LIMIT RAINFALL
AMOUNTS. AS THE UPPER LOW MOVES NORTHEAST...MUCH COLDER AIR WILL
ARRIVE WITH PTYPE CHANGING TO SNOW FOR MOST LOCATIONS WEDNESDAY. DO
NOT EXPECT SIGNIFICANT ACCUMULATION...WITH PERHAPS AN INCH OR SO ON
THE RIDGES AND ALONG THE I-80 CORRIDOR.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
HIGH PRESSURE MOVES IN FOR THURSDAY AND WILL BRING DRY BUT CHILLY
CONDITIONS. MODELS HAVE BEEN CONSISTENT WITH A WEAK COLD FRONT
CLIPPING THE AREA LATE FRIDAY/FRIDAY NIGHT. WITH LIMITED
MOISTURE...WILL USE LOW END CHANCE POPS. DRY AND CHILLY CONDITIONS
ARE EXPECTED FOR SATURDAY...WITH A SMALL CHANCE OF PRECIP COMING
IN FOR LATE SUNDAY AND MONDAY.
&&
.AVIATION /06Z TUESDAY THROUGH FRIDAY/...
BLEND OF RECENT SURFACE AND RADAR DATA ALONG WITH HRRR AND NAM MODEL
OUTPUT SHOW COLD FRONTAL BAND OF RAIN MOVING NORTHEASTWARD THROUGH
THE UPPER OHIO VALLEY THIS MORNING INTO EARLY AFTERNOON.
INITIAL AVIATION CONCERN WILL BE THE WIND. SURFACE WINDS WILL BE
EAST NEAR 10 KTS, WHILE WINDS FROM 2 KFT AGL UP WILL BE SOUTHEAST AT
40 KTS, WHICH CAN PRODUCE LOW LEVEL WIND SHEAR. JUST PRIOR TO THE
RAIN BAND ONSET, THE FAST WINDS CAN MIX TO THE SURFACE TO CAUSE
GUSTS OF 25-30 KTS, AS EVIDENCED BY RECENT SURFACE DATA OVER THE
MOUNTAINS.
WITHIN THE FRONTAL RAIN BAND, FLIGHT CONDITIONS WILL DETERIORATE TO
MVFR WITH SHORT-LIVED IFR POSSIBLE IN HEAVIER RAINFALL.
WITH PASSAGE OF THE COLD FRONT, SURFACE WINDS WILL SHIFT INTO THE
SOUTHWEST WITH GUSTS TO 20-25 KTS. POST FRONTAL CONDITIONS THIS
AFTERNOON AND TONIGHT WILL BE MAINLY MVFR IN INTERMITTENT SHOWERS.
THERE CAN BE A DRY SLOT WITH VFR CONDITIONS LATE AFTERNOON INTO
EVENING, FOLLOWED BY RENEWED SHOWERS TONIGHT DUE TO WRAP AROUND
DYNAMICS.
SURFACE TEMPERATURES WILL DROP INTO THE 30S, BUT NAM MODEL PROFILES
SUGGEST CLOUDS MAY BE TOO SHALLOW TO PRODUCE A CHANGE TO SNOW
SHOWERS AS CLOUD TOP TEMPERATURES CAN BE WARMER THAN THE M10C NEEDED
FOR ICE NUCLEI INITIATION.
OUTLOOK...WEDNESDAY THROUGH SATURDAY....
CONTINUED POST SYSTEM WRAP AROUND SHOWERS MAY CAUSE ADDITIONAL
PERIODS OF MAINLY MVFR RESTRICTIONS INTO WEDNESDAY NIGHT. THEN
MAINLY VFR UNDER HIGH PRESSURE THURSDAY INTO SATURDAY. ALBEIT
THERE IS A SMALL CHANCE OF SHOWERS WITH RESTRICTIONS NORTH FROM A
PASSING GREAT LAKES COLD FRONT FRIDAY NIGHT.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1220 AM EST TUE NOV 29 2011
UPDATED AVIATION DISCUSSION FOR 06Z TAFS
.SYNOPSIS...
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW PROGRESSIVE FLOW ACROSS
SRN CANADA...FEATURING A WEAK RIDGE OVER SW CANADA...A SHORTWAVE
TROF OVER MANITOBA AND ANOTHER SHORTWAVE OVER QUEBEC. A CUTOFF LOW
IS OVER THE LWR MISSISSIPPI VALLEY. INCREASING SW FLOW AHEAD OF THE
MANITOBA SHORTWAVE HAS SCOURED OUT LOW CLOUDS ACROSS MOST OF THE
FCST AREA WITH DOWNSLOPING NEAR LAKE SUPERIOR AIDING THE CLEARING
TREND. AS OF 2030Z...LAST OF THE LOW CLOUDS ARE DOWNWIND OF LAKE
MICHIGAN...E OF KESC-GRAND MARAIS LINE. APPROACHING COLD FRONT
ASSOCIATED WITH MANITOBA SHORTWAVE IS NOT ACCOMPANIED BY ANY PCPN S
OF THE INTERNATIONAL BORDER AS AIRMASS IS DRY PER 12Z SOUNDINGS. &&
.SHORT TERM /TONIGHT AND TUE/...
SHORT TERM WILL BE GENERALLY QUIET AS OVERALL DRY AIRMASS LIMITS ANY
PCPN POTENTIAL DESPITE PASSAGE OF SHORTWAVE. COLD FRONT ASSOCIATED
WITH SHORTWAVE MOVING ACROSS ONTARIO TONIGHT WILL BRING A WIND SHIFT
AND USHER IN A PERIOD OF DECENT CAA (850MB TEMPS FALL FROM 0 TO 2C
THIS EVENING TO -6 TO -8C BY 12Z TUE). SHOULD BEGIN TO SEE AN
INCREASE IN LAKE EFFECT CLOUDS OVERNIGHT AS OVERWATER INSTABILITY
IMPROVES. OTHERWISE...NO PCPN IS EXPECTED AS AIRMASS IS DRY.
ON TUE...BRISK N WINDS AND MORE THAN ADEQUATE OVERWATER INSTABILITY
WILL LEAD TO QUITE A BIT OF STRATOCU OFF LAKE SUPERIOR. ALTHOUGH
850MB TEMPS ARE MARGINALLY COLD TO SUPPORT FLURRIES/-SHSN OFF THE
LAKE...TEMPS IN THE SHALLOW MOIST LAYER ARE JUST ABOVE -10C. IF
ANYTHING...THERE MIGHT BE SOME -FZDZ...BUT SUBCLOUD LAYER ON FCST
SOUNDINGS LOOKS TOO DRY TO SUPPORT THAT. THE LACK OF LOW CLOUDS WELL
UPSTREAM SUPPORTS MODEL FCST OF SOMEWHAT DRIER LOWER BOUNDARY LAYER.
IF THERE SOMEHOW IS A LITTLE PCPN TUE...IT WOULD PROBABLY BE OVER
NCNTRL UPPER MI (ERN BARAGA/MARQUETTE/WRN ALGER) DUE TO
PRECONDITIONING/STREAMLINE OFF LAKE NIPIGON INTO THAT AREA. IT WILL
BE A SEASONABLY CHILLY DAY WITH HIGHS IN THE UPPER 20S TO MID 30S.
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
TUESDAY NIGHT THROUGH WEDNESDAY EVENING...
WITH THE CONTINUED NORTHEASTWARD EJECTION OF
THE CUT OFF LOW OVER THE OHIO VALLEY AT 00Z WEDNESDAY TO THE LOWER
GREAT LAKES BY DAYBREAK WEDNESDAY...AND ACROSS QUEBEC THEREAFTER.
THE RESULT FOR THE UPPER GREAT LAKES WILL BE A 500MB RIDGE
OVERHEAD...AND A RIDGE OF HIGH PRESSURE EXTENDING ACROSS THE AREA
FROM TX. SENSIBLE WEATHER WISE...EXPECT DRY CONDITIONS WITH WARMING
ALOFT FROM A CWA AVERAGE -4 TO -1C AT 850MB DURING THE PERIOD.
THURSDAY MORNING THROUGH FRIDAY MORNING...
THE NEXT FEATURE OF INTEREST WILL BE SLIDING ACROSS EASTERN MT
WEDNESDAY MORNING...AND BETTER ORGANIZING FROM ND TO EASTERN CO BY
18Z WEDNESDAY. THE FEATURE WILL THEN WEAKEN AS IT SETS UP FROM UPPER
MI THROUGH TX BY 18Z THURSDAY. WITH THE ASSISTANCE OF SOME MID LEVEL
SUPPORT ON THE NORTHERN EDGE OF THIS FEATURE /500MB TROUGH EXTENDING
SW FROM THE NORTHERN PORTIONS OF HUDSON BAY/ LIGHT PRECIPITATION
WILL BE POSSIBLE...MAINLY BEHIND THE SFC LOW. NORTHERLY FLOW AND
850MB TEMPS OF -7 TO -9C BY 18Z THURSDAY SHOULD BRING ABOUT LIGHT
SNOW SHOWERS. INDICATIONS CONTINUE TO POINT AT 1 TO 3 INCHES OF SNOW
THURSDAY ACROSS THE KEWEENAW PENINSULA...WITH VALUES REMAINING BELOW
ADVISORY HEADLINE CRITERIA AT THIS TIME. COOLER NW FLOW WILL THEN
DOMINATE THURSDAY NIGHT WITH 850MB TEMPS BOTTOMING OUT AROUND -13C
BY 12Z FRIDAY...WHILE THE 500MB AXIS AND SFC FRONT EXIT TO OUR
EAST...LIMITING SIGNIFICANT SNOWFALL ACCUMULATIONS.
FRIDAY AFTERNOON AND EVENING...
WAA WILL QUICKLY TAKE HOLD FRIDAY AFTERNOON THROUGH THE EVENING
HOURS WITH 850MB TEMPS REBOUNDING TO AROUND -1 TO -4C DEPENDING ON
WHAT MODEL YOU BELIEVE...AND A WEAK RIDGE SLIDING ACROSS ALOFT.
EITHER WAY IT SHOULD BE DRY WITH SW WINDS...WITH THE LAST OF THE
LAKE EFFECT/LAKE ENHANCED PRECIP ENDING AT 12Z FRIDAY ON MAINLY
WESTERLY WINDS.
BEYOND FRIDAY EVENING THE FORECAST BEGINS TO BECOME A LITTLE LESS
PREDICTABLE. A 500MB TROUGH SET UP FROM N CENTRAL CANADA THROUGH MT
AT 18Z FRIDAY WILL ATTEMPT TO PUSH A SOUTHWESTERN U.S. CUT OFF LOW
INTO THE MAIN FLOW OVER THE WEEKEND...WITH THE ELONGATED TROUGH
SLIDING OVER THE UPPER GREAT LAKES SOMETIME BETWEEN SATURDAY MORNING
AND SUNDAY AFTERNOON...WITH AN ADDITIONAL WAVE ALMOST RIGHT BEHIND
THE PRIMARY WAVE FOR SUNDAY AFTERNOON OR MONDAY AFTERNOON.
YES...THERE IS NEARLY A 24 HOUR DIFFERENCE BETWEEN THE 28/00Z RUN OF
THE ECMWF AND THE 28/00Z AND 06Z RUNS OF THE GFS. THE 12Z RUNS OF
THE GFS AND ECMWF HAVE COME INTO A LITTLE BETTER AGREEMENT ONCE
AGAIN...AND WE WILL HAVE TO WAIT AND SEE IF THIS TREND CONTINUES.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/...
EXPECT MVFR CONDITIONS TO PREVAIL THRU MUCH OF THE FCST PD AS LAKE
CLOUDS WILL MOVE IN TONIGHT BEHIND A COLD FRONT. INITIALLY...WARMER
AIR BEHIND THE FRONT MAY LIMIT LAKE CLOUD FORMATION FOR THE EARLY
OVERNIGHT...BUT AS AIRMASS BECOMES COLDER AND OVERWATER INSTABILITY
INCREASES...EXPECT STRATOCU/MVFR CIGS TO DEVELOP OFF LAKE SUPERIOR
AND AFFECT KIWD/KCMX/KSAW THROUGH MUCH OF THE DAY ON TUESDAY.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
TYPICAL CHANGEABLE LATE FALL PATTERN EXPECTED THIS WEEK. COLD FRONT
WILL PASS ACROSS THE AREA TONIGHT. MAY SEE A FEW GALE FORCE GUSTS
BTWN ISLE ROYALE AND THE KEWEENAW LATE THIS AFTN IN THE SW FLOW
AHEAD OF THE FRONT. BEHIND THE FRONT IN DECENT CAA REGIME...THERE
MAY BE SOME NORTHERLY GALE FORCE GUSTS FROM NCNTRL TO SCNTRL LAKE
SUPERIOR OVERNIGHT/EARLY TUE AS OVERWATER INSTABILITY INCREASES. AT
THIS TIME...IT APPEARS GALE GUSTS SHOULDN`T BE WIDESRPEAD OR
PERSISTENT ENOUGH TO WARRANT A GALE WARNING. WINDS WILL SLOWLY
DIMINISH FROM W TO E TUE AFTN/NIGHT AS HIGH PRES RIDGE MOVES CLOSER
TO THE AREA. LIGHTER WINDS UNDER 20KT WILL BE THE RULE WED
AFTN/NIGHT UNDER WEAK PRES GRADIENT ASSOCIATED SFC TROF SETTLING SE
INTO THE UPPER LAKES. N TO NW WINDS WILL INCREASE INTO THE 15-25KT
RANGE THU/THU NIGHT AS THE TROF SLIPS SE OF THE AREA. AFTER A BRIEF
PERIOD OF LIGHTER WINDS LATE THU NIGHT/FRI MORNING...WINDS WILL
AGAIN BE ON THE INCREASE LATER FRI INTO SAT AHEAD OF THE NEXT LOW
PRES TROF APPROACHING FROM THE NW. MAY SEE GALES IN THE SW FLOW
AHEAD OF THE TROF.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
GALE WARNING FROM 7 AM TO 7 PM EST TUESDAY FOR LMZ221-250.
&&
$$
SYNOPSIS...ROLFSON
SHORT TERM...ROLFSON
LONG TERM...KF
AVIATION...JV
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
556 PM CST WED NOV 30 2011
.AVIATION... /00Z TAF ISSUANCE/
COLD FRONT CURRENTLY MEANDERS FROM NORTH OF KEAU TO JUST SOUTH OF
KMSP AND KRWF. THE FRONT WILL MOVE SLOWLY SOUTHEAST OVERNIGHT.
MVFR OR LOWER CEILINGS ALONG WITH LIGHT SNOW IS BEGINNING TO DRIFT
SOUTH INTO CENTRAL MN. LOWER CEILINGS/SNOW SHOULD BEGIN TO IMPACT
KAXN AFTER 02Z AND KSTC AFTER 04Z. CEILINGS ARE MORE OF A CONCERN
WITH POTENTIAL TO FALL UNDER 010 FOR SEVERAL HOURS. THE FORCING
WITH THIS SYSTEM REALLY COMES TOGETHER AFTER 09Z WITH THE IMPACT
THROUGH DAYBREAK BEING KRWF THROUGH KMSP...KRNH AND KEAU ON
SOUTHWARD. CEILINGS FROM 010-020 LIKELY ALONG WITH A 3 TO 6 HOUR
PERIOD OF SNOW REDUCING VISIBILITY TO AROUND 1 MILE. ACCUMULATIONS
UP TO AN INCH ARE POSSIBLE. CLEARING SHOULD COMMENCE BY 15Z ACROSS
CENTRAL MN AND BY EARLY AFTERNOON FOR SOUTHERN MN AND WEST CENTRAL
WI. NORTHWEST WINDS WILL AROUND 12 KNOTS FROM MID MORNING THROUGH
THE AFTERNOON WITH SOME GUSTS TO 18 KNOTS.
KMSP...COLD FRONT NOW SOUTH OF THE AIRFIELD WITH LIGHT NORTH TO
NORTHEAST WINDS THIS EVENING. FORECAST REMAINS ON TRACK FOR A
PERIOD OF MVFR CEILINGS AND SNOW MOVING THROUGH FROM 09Z-14Z.
WORST TIME LOOKS TO BE IN THE 11Z TO 12Z TIME FRAME WHERE CEILINGS
MAY DIP UNDER 010 ALONG WITH VISIBILITIES OF 3/4SM TO 1SM. SNOW
ACCUMULATION OF A HALF INCH LIKELY WITH LESSER PROBABILITIES IT
COULD REACH AN INCH. CLEARING FOR THE AFTERNOON WITH NORTHWEST
WINDS 12-15 KNOTS.
&&
.DISCUSSION... /ISSUED 312 PM CST WED NOV 30 2011/
TONIGHT THROUGH THURSDAY...AT THE SFC A WEAK COLD FRONT WILL
SLOWLY GLIDE S ACRS SRN MN/SW WI THROUGH THE OVERNIGHT HOURS INTO
THU MRNG. AS IT DROPS S...A RELATIVELY WEAK AREA OF LOW PRESSURE
IS EXPECTED TO DEVELOP ALONG IN INVOF MN/IA BORDER. FAIRLY DEEP
MOISTURE...AS SHOWN BY AN EXTENSIVE CLOUD SHIELD ON VIS SAT
IMAGERY AND RATHER MOIST RUC SOUNDINGS...IS AVAILABLE FOR A DECENT
MIDLVL SHORTWAVE TROUGH AXIS TO PRODUCE PRECIP MAINLY AFTER
MIDNIGHT AND THROUGH SUNRISE. TAKING THE FORM OF ALL SNOW... WILL
LOOK FOR ENOUGH QPF TO PRODUCE ONE HALF TO ONE AND A HALF INCHES
OF SNOW WITH THE HEAVIEST OF THE SNOW OCCURRING DURING THE MORNING
COMMUTE HOURS. THE GREATER OF THE SNOW ACCUMULATIONS WILL EAST AND
SOUTH OF THE TWIN CITIES METRO. ALTHOUGH CONVECTIVE SNOWS ARE NOT
APPARENT ON EVEN SHORT-TERM MODELS PARTICULARLY WITH SFC
CONVERGENCE AND LIFT RATHER WEAK...THE UPPER LEVEL SUPPORT
AVAILABLE DOES NOT RULE OUT AN ISOLATED BURST OF HEAVIER SNOW THAT
COULD PRODUCE UP TO 2 INCHES IN A SHORT AMOUNT OF TIME...MAINLY
OVER WRN WI WHERE JET DYNAMICS LOOK TO POTENTIALLY ENHANCE PRECIP
THURSDAY MORNING. THE PRECIP WILL GRADUALLY TAPER OFF DURING THE
LATE MORNING THROUGH AFTERNOON HOURS TOMORROW WITH VERY LITTLE
LEFT BY LATE AFTERNOON. AS FOR TEMPERATURES...THE POTENT COLD
FRONT WILL EFFICIENTLY LEAD THE WAY FOR H85 TEMPS IN THE -7 TO -10
DEG C RANGE TO DROP THROUGH THE REGION DURING THE DAY TOMORROW...
MAKING FOR A VERY SMALL DIURNAL RANGE FROM LOW TEMPS TONIGHT TO
HIGHS TMRW. LOWS TONIGHT WILL RANGE FROM THE LWR 20S NW TO AROUND
30 SE AND IN THE METRO...FOLLOWED BY HIGHS THU FROM THE MID 20S NW
TO THE LWR 30S SE.
THURSDAY NIGHT THROUGH SUNDAY...SKIES WILL SLOWLY CLEAR OUT THU
NIGHT INTO FRI THE UPPER LEVEL TROUGH DROPS S OF THE REGION AND A
BUBBLE HIGH PRES RIDGE MOVES ACROSS THE NRN PLAINS INTO THE GREAT
LAKES. AT THE SFC...A SPOKE OF HIGH PRES EXTENDING NE FROM THE
CENTRAL PLAINS WILL ROTATE THROUGH...ALLOWING FOR DECENT
RADIATIONAL COOLING CONDITIONS THU NIGHT AS WINDS DROP TO BELOW 7
MPH. LOWS WILL FALL TO THE UPPER SINGLE DIGITS TO THE MID TEENS.
EVEN WITH THE CLEAR SKIES CONTINUING ON FRI AND SFC FLOW TURNING
MORE SLY...NW TO W UPPER FLOW AND H85 TEMPS ARND -5 DEG C WILL
KEEP HIGHS ON FRI JUST BELOW FREEZING. THE WEATHER STORY BECOMES
VERY INTERESTING FRI NIGHT THROUGH SAT NIGHT AS AS UPPER LEVEL LOW
CHURNING IN THE SOUTHWEST BECOMES CAUGHT UP IN A NORTHERN STREAM
LONGWAVE TROUGH AXIS PUSHING THRU WRN CANADA AND THE NRN PLAINS
STATES. BOTH UPPER SYSTEMS INTERACT BUT IN PIECES...AND A FEW
PIECES OF ENERGY WILL SHIFT NE FROM THE SOUTHWEST TWD THE GREAT
LAKES SAT AS CYCLOGENESIS OCCURS OVER THE TX PANHANDLE. THIS
NEWLY-GENERATED SFC LOW WILL RACE NE LATE SATURDAY THROUGH SAT
NIGHT BUT THE BIGGER PROBLEM IS HOW CLOSE AN UPPER SHORTWAVE
TROUGH AXIS COMES TO INTERACT WITH IT. MOISTURE TRANSPORT AHEAD OF
THIS NEW SFC LOW INCREASES AND THE INCOMING UPPER TROUGH WILL
ENHANCE LIFT. GIVEN THE COLD TEMPERATURES IN PLACE...P-TYPE ISSUES
WILL NOT BE PRESENT FOR THE WFO MPX CWFA AS PRECIP WOULD BE ALL
SNOW. THERE IS STILL MUCH MODEL DISAGREEMENT IN THE PLACEMENT OF
THE MAIN PLAYERS INVOLVED...AND THIS IS RELAYED VIA MODEL SNOWFALL
ACCUMS WHICH COULD BE UP TO A COUPLE OF INCHES TO OVER 6 INCHES
WITH THE HIGHEST AMOUNTS FOR SOUTHERN AND EASTERN PORTIONS OF THE
COVERAGE AREA. HAVE NUDGED POPS INTO THE LIKELY CATEGORY FOR THOSE
AREAS...TRENDING DOWN GOING WEST AND NORTH...AND HAVE KEPT
SNOWFALL AMOUNTS CAPPED AT 4 INCHES FOR FAR SRN AND ERN FRINGES
WITH NO SNOW EXPECTED FOR THE NWRN TIERS. THIS SYSTEM QUICKLY
EJECTS TO THE E SAT NIGHT INTO SUN...ALLOWING FOR AT LEAST PARTIAL
CLEARING DURING THE DAY SUNDAY BEFORE ANOTHER AREA OF LOW PRESSURE
DROPS IN FROM MANITOBA LATE SUN INTO SUN NIGHT. THERE IS POTENTIAL
FOR VERY LIGHT ACCUMS OVER NRN TIERS OF THE COVERAGE AREA BUT WITH
SO MUCH UNCERTAINTY WITH THIS SATURDAY SYSTEM...IT IS DIFFICULT TO
PINPOINT THINGS WITH THE LATE SUNDAY SYSTEM SO HAVE KEPT POPS IN
THE SLGT CHC CATEGORY. TEMPERATURES WILL RUN NEAR TO SLIGHTLY
ABOVE NORMAL THRU FRI...THEN DROP TO SLIGHTLY BELOW NORMAL OVER
THE WEEKEND.
MONDAY THROUGH WEDNESDAY...THE AFOREMENTIONED LOW ON SUNDAY WILL
MOVE INTO THE GREAT LAKES MONDAY...FOLLOWED BY RIDGING BOTH AT THE
SFC AND ALOFT FOR THE START OF NEXT WEEK. COLDER PUNCHES OF AIR
DROPPING S FROM NRN-CENTRAL CANADA WILL KEEP TEMPS BELOW NORMAL
FOR THE FIRST HALF OF NEXT WEEK. HAVE KEPT A PREDOMINANTLY DRY
FORECAST GOING DUE TO THE LACK OF BONA FIDE SYSTEMS PROGGED FOR
THIS PERIOD.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
RAH/TRH
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1152 PM CST MON NOV 28 2011
.UPDATE...
/926 PM CST MON NOV 28 2011/
RADAR TRENDS ARE SHOWING SOME INCREASE CURRENTLY OVER THE EASTERN
OZARKS. DO NOT EXPECT ADDITIONAL AMOUNTS OF SNOW AND SLEET TO BE
MUCH MORE THAN A HALF INCH AS VISIBILITIES AT OBSERVATION SITES
ARE NOT DROPPING MUCH AND THERE IS NO SIGNIFICANT COOLING ON IR
IMAGERY. RUC AND OTHER MODELS SOUNDINGS ARE SHOWING SOME WEAK
WARMING THROUGH A DEEP LAYER THE REST OF THE NIGHT AT THE SAME
TIME ASCENT WILL WEAKEN. TOTAL SNOW AND SLEET AMOUNTS IN THE FAR
SOUTHERN CWA STILL LOOK LIKE THEY WILL BE 1 TO 2 INCHES WITH
AMOUNTS DROPPING OFF QUICKLY TO THE NORTH. REST OF THE FORECAST
STILL LOOK GOOD.
BRITT
&&
.DISCUSSION...
/341 PM CST MON NOV 28 2011/
UPPER LOW CUT OFF LATE LAST NIGHT OVER SE AR AND DURING THE DAY
TODAY SYSTEM HAS BEGUN TO PIVOT TO THE NORTHEAST...PERHAPS JUST A
BIT FURTHER E THAN FORECAST BY EARLIER NWP OUTPUT. NO QUESTION THAT
THIS SYSTEM WILL BRING PRECIPITATION TO SE SECTIONS OF THE CWA
OVER THE NEXT 24 HOURS...AS LATEST MODEL RUNS CONTINUE TO SUPPORT
EARLIER THINKING THAT VERY MOIST AIRMASS WILL BE UNDERGOING STRONG
ISENTROPIC ASCENT AS IT WRAPS AROUND THE NORTH SIDE OF THE LOW FROM
THE OHIO VALLEY INTO SE MO. ISENTROPIC PROGS INDICATE THAT THERE
WILL BE AN EXTREMELY TIGHT POP GRADIENT/SHARP CUTOFF IN PRECIP ON
THE WESTERN EDGE OF THE PRECIP SHIELD...AND FOR NOW WE`RE HOLDING
ONTO THE THINKING THAT THIS EDGE WILL BE JUST EAST OF A IJX-VIH
LINE. ANY SMALL WOBBLE IN THE TRACK OF THE SYSTEM MAY CAUSE A
FAIRLY BIG ADJUSTMENT TO THE POPS IN THIS CORRIDOR.
BIGGEST CONCERN FOR AREA IS PTYPE...AND 12Z UA DATA INDICATED AMS
LOCKED TO THE WEST OF THE SYSTEM WAS JUST A BIT COOLER THAN
SUGGESTED BY EARLIER RUNS. THERE COULD BE A MIX OF PTYPES EARLY
THIS EVENING WITH THE INITIAL ONSET OF THE PRECIP...BUT THE
INTENSE NATURE OF THE PROGGED WAA ACROSS AREA CERTAINLY SUGGESTS
THAT WARM AIR WILL OVERWHELM COLUMN AND AS A RESULT MOST OF THE
PRECIP FROM MID EVENING ON WILL FALL IN THE FORM OF RAIN. THE
EXCEPTION TO THIS IS THE E OZARKS...WHERE FORECAST SOUNDINGS DO
INDICATE THAT POCKET OF LOW LEVEL COLD AIR IS GOING TO STUBBORNLY
HOLD ON. IN THIS AREA...PRIMARILY ALONG AND SOUTH OF A STE
GENEVIEVE...POTOSI LINE...HAVE CONTINUED TO A MENTION OF SNOW AND
SLEET ALONG WITH THE RAIN THROUGHOUT THE NIGHT. ANY ACCUMULATIONS
SHOULD BE MINOR BUT CERTAINLY NOT OUT OF THE QUESTION...ESPECIALLY
IF DYNAMIC COOLING CAN DROP TEMPS ENOUGH IN A LOCALIZED AREA.
PRECIP WINDS DOWN FROM EASTERN MO INTO S CENTRAL IL DURING THE DAY
ON TUE...WITH THE BULK OF THE PRECIP EAST OF THE MISSISSIPPI RIVER
BY MIDDAY. THE DECREASE OF THE WAA AS THE SYSTEM PUSHES INTO THE
LOWER GREAT LAKES DOES ALLOW AMS OVER AREA TO BEGIN TO COOL ONCE
AGAIN...BUT FOR THE MOST PART IT LOOKS LIKE PRECIP WILL BE SHUTTING
DOWN BY THE TIME THERMAL PROFILES WOULD SUPPORT A MIX AND/OR A
CHANGEOVER TO ALL SNOW. SO...OTHER THAN CONTINUING A MENTION OF
SOME LINGERING LIGHT SNOW IN THE AFOREMENTIONED POCKET OF COOL AIR
OVER THE OZARKS...HAVE MAINTAINED ALL RAIN IN THE FORECASTS FOR TUE.
TRANQUIL WEATHER WILL RETURN FOR MID WEEK WITH TEMPS REBOUNDING TO
NEAR OR JUST ABOVE THE 50 DEGREE MARK OVER S MO ON
THURSDAY...ALTHOUGH A DRY COLD FRONTAL PASSAGE SHOULD KNOCK DAYTIME
TEMPS BACK INTO THE 30S AND 40S BY FRIDAY.
NEXT SYSTEM SHOULD BEGIN TO PUSH OUT OF THE WESTERN U.S. AND INTO
THE PLAINS LATE SATURDAY-SUNDAY TIME FRAME...WITH PRECIP RETURNING
TO THE AREA DURING THIS TIME. SOME QUESTION AS TO WHAT THE PTYPE
MAY BE...BUT FOR NOW HAVE GONE WITH A BROAD-BRUSH RAIN/SNOW MIX AND
WILL FINE-TUNE AS WE GET CLOSER TO EVENT.
GKS/TRUETT
&&
.AVIATION...
/1121 PM CST MON NOV 28 2011/
MVFR CIGS HAVE FINALLY ERODED OVER KCOU/KUIN AND VFR CONDITIONS
ARE EXPECTED AT THOSE SITES FOR THE REST OF THE NIGHT. WINDS WILL
GRADUALLY INCREASE TONIGHT AS THE PRESSURE GRADIENT TIGHTENS
BETWEEN A DEPARTING LOW PRESSURE SYSTEM OVER THE OHIO VALLEY AND
AN APPROACHING SURFACE RIDGE AXIS.
SPECIFICS FOR KSTL AND KSUS...KSTL/KSUS REMAIN ON THE WRN FRINGE
OF A SHARP PCPN GRADIENT AND PDS OF LGT RAIN SHOULD CONTINUE
THROUGH MOST OF THE NIGHT. MVFR CIGS WILL PERSIST THROUGH MOST OF
THE DAY WITH RAPID IMPROVEMENT BY LATE AFTN AS THE LOW PRESSURE
SYSTEM LIFTS AWAY FROM THE REGION. WINDS WILL GRADUALLY INCREASE
OVERNIGHT AS THE PRESSURE GRADIENT TIGHTENS.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
615 AM EST TUE NOV 29 2011
.SYNOPSIS...
COOLER AND DRIER AIR WILL BE USHERED IN FROM THE WEST TODAY. HIGH
PRESSURE WILL BUILD ACROSS THE EASTERN CAROLINAS FOR THE REMAINDER
OF THE WEEK. THIS HIGH WILL SHIFT OFF THE NORTHEAST COAST OVER THE
WEEKEND POSSIBLY ALLOWING FOR A SLIGHT MODERATION BACK TOWARDS
SEASONABLE TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AS OF 330 AM EST TUESDAY...LEADING EDGE OF THE LINE OF CONVECTION
HAS PUSHED ENTIRELY THROUGH THE ILM CWA. ITS POTENTIAL TO PRODUCE
SEVERE WEATHER HAS DIMINISHED CONSIDERABLY. RIGHT NOW...IT CONTINUES
TO PRODUCE DRAMATIC WIND SHIFTS WITH CAA IMMEDIATELY BEHIND IT. POST
FRONTAL RAINS WILL BE THE MAINSTAY THIS MORNING. A NARROW BAND OF
DEEP MOISTURE FROM THE SUBTROPICS/TROPICS WILL KEEP THE POST FRONTAL
RAINS ONGOING INTO DAYLIGHT TUESDAY. UNUSUAL FOR POSTFRONTAL
RAINS...ESPECIALLY WITH PROGGED WIDESPREAD AMOUNTS IN THE ONE
QUARTER TO ONE HALF INCH...ALONG WITH ISOLATED 2+ INCHES. THE HIGHER
AMOUNT HAS ALREADY OCCURRED IN A 15 MILE WIND SWATH BETWEEN
JOHNSONVILLE OF SE FLORENCE COUNTY NORTHWARD ACROSS CENTRAL MARION
COUNTY TO MINTURN OF WESTERN DILLON COUNTY. PER LATEST HRRR MODEL
RUNS...THE TREND HAS BEEN ENDING THE PCPN BY MID MORNING ILM SC
COUNTIES TO LATE MORNING ACROSS THE ILM NC COUNTIES.
THE UPPER CLOSED LOW WILL BE LIFTING NE ALONG THE BACKBONE OF THE
APPALACHIANS THROUGHOUT THE NEAR TERM...REACHING THE EASTERN GREAT
LAKES WED MORNING. THERE IS ONE MID LEVEL VORTICITY LOBE SPIRALING
AROUND THE UPPER CLOSED LOW...WHICH AFFECTS THE FAR NW PORTIONS OF
THE ILM CWA WITH PVA DURING THIS AFTERNOON. SOME OF THE DEEPER
MOISTURE ROTATING AROUND THE UPPER LOW DOES MOVE ACROSS THE ILM CWA
AT THE SAME TIME THIS VORT DOES. WILL INCLUDE LOW CHANCE FOR POPS TO
ACCOMMODATE. WILL KEEP IT AS LIQUID RAINSHOWERS EVENTHOUGH 850MB
TEMPS ARE PROGGED TO DROP TO -2 ACROSS THIS AREA...HOWEVER THE
1000-850MB THICKNESSES ARE STILL PROGGED ABOVE 1300 THE USUAL
THICKNESS TO SEE FROZEN PCPN. FOR MAX/MIN TEMPS OPTED TO USE THE
LOWER END OF GUIDANCE DUE TO CAA ALREADY OCCURRING. WITH EXCELLENT
LOW LEVEL LAPSE RATES ESPECIALLY DURING THE INSOLATION PART OF THE
DAY...BROKEN TO OVERCAST STRATOCU WILL OVERSPREAD THE ILM CWA.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...COOL AND DRY WEATHER IS ON TAP FOR THE DURATION
OF THE SHORT TERM PERIOD. CUTOFF UPPER LOW WILL BE QUICKLY EXITING
TO THE NE ACRS NY AND INTO NEW ENGLAND STATES EARLY WED WITH
LINGERING VORT MAX IN THE TRAILING PART OF THE TROUGH OVER ARKANSAS.
THIS FEATURE WILL CUT TO OUR SOUTH WEDNESDAY EVENING. WITH THE LOW
LEVELS ADVECTING COOL AND DRY AIR HOWEVER THIS UPPER FEATURE WILL
HAVE LITTLE TO NO EFFECT ON SENSIBLE WEATHER. THIS LOW WILL DEEPEN
JUST OFF THE COAST OF THE CAROLINAS EARLY THURSDAY BUT WILL QUICKLY
ACQUIRE A NEGATIVE TILT ALLOWING FOR HEIGHT RISES OVER THE COASTAL
PLAIN TO MOVE IN FROM THE WEST BY THE AFTERNOON. THESE HEIGHT RISES
WILL NOT BE REALIZED AT THE SURFACE...NORMALLY IN THE FORM OF
WARMING TEMPERATURES. WEAK SURFACE HIGH ACROSS THE SOUTHEAST WILL
KEEP MIXING FAIRLY SHALLOW. BOTH DAYS WILL BRING HIGHS IN THE UPPER
50S AND LOWS IN THE LOW TO UPPER 30S...MILDEST ALONG THE COAST BY
NIGHT.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...LOW AMPLITUDE UPPER RIDGING CROSS THE AREA
FRIDAY AND SATURDAY WHILE SURFACE HIGH PRESSURE REMAINS TO OUR NNE.
THE LATTER WILL TEND TO OFFSET THE WARMING OF THE FORMER TO KEEP
TEMPS BELOW CLIMO. LARGE POSITIVELY TILTED TROUGHINESS DEVELOPS
OVER THE NORTH-CENTRAL PORTION OF THE COUNTRY FOR THE REMAINDER OF
THE PERIOD KEEPING THE AREA DRY. THE HIGH TO OUR NORTH SHOULD
PROGRESS TO THE EAST ENOUGH TO ALLOW FOR A SLIGHT MODERATION OF
TEMPS ESP BY MONDAY.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 12Z...COLD FRONT HAS NOW PAST WELL EAST OF THE CWA...WITH POST
FRONTAL RAIN WITH A MIXTURE OF MVFR AND VFR STRATA CU CEILINGS.
EXPECT VFR TO PREVAIL AT ALL TERMINALS BY MID TO LATE MORNING AS THE
RAIN AND LOWER CEILINGS SLOWLY MOVE EAST. WINDS WILL ACTUALLY BACK
TO THE SOUTHWEST AS THE OCCLUDED SYSTEM SLOWLY PULLS OUT. THE GFS
HAS SOME MVFR STRATA CU LINGERING FOR MOST OF THE DAY...BUT LOW
CONFIDENCE ON THIS...GIVEN THAT MUCH OF THE AREA IS ALREADY 4K FT OR
HIGHER. HAVE BACKED OFF A BIT ON THE GUSTS TODAY...BUT A GUST TO 20
KTS IS NOT OUT OF THE QUESTION. BY LATE AFTERNOON...MOST IF NOT ALL
OF THE DEEP MOISTURE EXITS THE REGION...WITH SCATTERED SKIES
EXPECTED. LOWERING DEWPOINTS AND MODERATE MIXING WILL ALLOW WINDS TO
STAY 10 KTS OR SO THROUGH MUCH OF THE EVENING HOURS.
EXTENDED OUTLOOK...EXPECT VFR THROUGH PERIOD.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 345 AM TUESDAY...SFC COLD FRONT HAS PUSHED ACROSS THE LOCAL
WATERS EARLY THIS MORNING. THE ENSUING CAA UNDER SW-W WINDS 15-25 KT
WITH FEW GUSTS 30-35 KT WILL RULE THE DAY. THE SFC PG IS PROGGED TO
RE-TIGHTEN BY MIDDAY ACROSS THE WATERS RESULTING IN SUSTAINED WIND
SPEEDS ON THE HIGHER SIDE OF THE RANGE GIVEN. THE RISEN SEAS WILL
PEAK EARLY THIS MORNING...THEN SLOWLY SUBSIDE TODAY THROUGH TONIGHT.
SOME OF THE HIGHER SEAS...ESPECIALLY THE OUTER WATERS OFF CAPE FEAR
AND ROMAIN...WERE AIDED BY SEAS BLEEDING IN FROM THE OFFSHORE WATERS
WHERE WINDS AT GALE FORCE OCCURRED. THE LOW MID 70S SSTS WERE THE
BIG CONTRIBUTOR FOR THESE HIGHER WINDS MAKING IT TO THE OFFSHORE
OCEAN SFC. SWAN GUIDANCE FOR SEAS WAS USED...BUT DID NOT LOWER THEM
AS FAST AS WHAT SWAN WAS INDICATING. THE SCA MAY NEED TO BE
EXTENDED FURTHER INTO TONIGHT...ESPECIALLY THE WATERS FROM CAPE FEAR
NORTHWARD. AVERAGE PERIODS WILL RUN 6-8 SECONDS THROUGH EARLY THIS
AFTERNOON. THE AVERAGE PERIODS WILL DECREASE TO 4 TO 6 SECONDS LATE
THIS AFTERNOON AND TONIGHT DUE TO WESTERLY WINDS ACROSS A DIMINISHED
FETCH AREA.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...WESTERLY WINDS ON WEDNESDAY WILL BE THE LAST
REMAINING EFFECTS OF THE PREVIOUS STORM SYSTEM...WHICH BY WED WILL
BE RAPIDLY MOVING INTO THE NEW ENGLAND STATES. WIND WILL THEN
TRANSITION OVER TO NORTHERLY LATE WEDNESDAY DUE TO HIGH PRESSURE
BUILDING IN FROM THE WEST. A FAIRLY ROBUST UPPER SYSTEM WILL CROSS
THE WATERS EARLY THURSDAY. POOR DIRECTIONAL ALIGNMENT OF WIND IN THE
VERTICAL HOWEVER WILL PREVENT THIS FROM MAKING MUCH OF A DIRECT
EFFECT/INCREASE IN SURFACE WIND SPEEDS. NO HEADLINES EXPECTED THIS
PERIOD FOR THE MOST PART. THE EXCEPTION MAY BE TOWARDS THE END OF
THE PERIOD WHEN SOME 5 FT SEAS MANAGE TO AFFECT THE VERY OUTER
REACHES OF THE 20NM FCST ZONE.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...N TO NE FLOW ON THE SOUTHEAST PERIPHERY OF HIGH
PRESSURE WILL CHARACTERIZE MOST OF THE PERIOD. WHILE WIND SPEED MAY
SHOW LITTLE VARIATION THOUGH THE PERIOD THE INCREASING TIME OF THE
STEADY FETCH COULD ADD SLIGHTLY TO WAVE HEIGHTS. 5 FT SEAS MAY
OCCASIONALLY BE AFFECTING THE OUTER PORTIONS OF MAINLY THE NORTHERN
ZONES. IT IS THUS HARD TO ASCERTAIN THE NEED FOR ANY CAUTIONARY
HEADLINES THIS FAR OUT IN TIME.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST TUESDAY FOR AMZ250-252-
254-256.
&&
$$
SYNOPSIS...MBB
NEAR TERM...DCH
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
405 AM EST TUE NOV 29 2011
.SYNOPSIS...
COOLER AND DRIER AIR WILL BE USHERED IN FROM THE WEST TODAY. HIGH
PRESSURE WILL BUILD ACROSS THE EASTERN CAROLINAS FOR THE REMAINDER
OF THE WEEK. THIS HIGH WILL SHIFT OFF THE NORTHEAST COAST OVER THE
WEEKEND POSSIBLY ALLOWING FOR A SLIGHT MODERATION BACK TOWARDS
SEASONABLE TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AS OF 330 AM EST TUESDAY...LEADING EDGE OF THE LINE OF CONVECTION
HAS PUSHED ENTIRELY THROUGH THE ILM CWA. ITS POTENTIAL TO PRODUCE
SEVERE WEATHER HAS DIMINISHED CONSIDERABLY. RIGHT NOW...IT CONTINUES
TO PRODUCE DRAMATIC WIND SHIFTS WITH CAA IMMEDIATELY BEHIND IT. POST
FRONTAL RAINS WILL BE THE MAINSTAY THIS MORNING. A NARROW BAND OF
DEEP MOISTURE FROM THE SUBTROPICS/TROPICS WILL KEEP THE POST FRONTAL
RAINS ONGOING INTO DAYLIGHT TUESDAY. UNUSUAL FOR POSTFRONTAL
RAINS...ESPECIALLY WITH PROGGED WIDESPREAD AMOUNTS IN THE ONE
QUARTER TO ONE HALF INCH...ALONG WITH ISOLATED 2+ INCHES. THE HIGHER
AMOUNT HAS ALREADY OCCURRED IN A 15 MILE WIND SWATH BETWEEN
JOHNSONVILLE OF SE FLORENCE COUNTY NORTHWARD ACROSS CENTRAL MARION
COUNTY TO MINTURN OF WESTERN DILLON COUNTY. PER LATEST HRRR MODEL
RUNS...THE TREND HAS BEEN ENDING THE PCPN BY MID MORNING ILM SC
COUNTIES TO LATE MORNING ACROSS THE ILM NC COUNTIES.
THE UPPER CLOSED LOW WILL BE LIFTING NE ALONG THE BACKBONE OF THE
APPALACHIANS THROUGHOUT THE NEAR TERM...REACHING THE EASTERN GREAT
LAKES WED MORNING. THERE IS ONE MID LEVEL VORTICITY LOBE SPIRALING
AROUND THE UPPER CLOSED LOW...WHICH AFFECTS THE FAR NW PORTIONS OF
THE ILM CWA WITH PVA DURING THIS AFTERNOON. SOME OF THE DEEPER
MOISTURE ROTATING AROUND THE UPPER LOW DOES MOVE ACROSS THE ILM CWA
AT THE SAME TIME THIS VORT DOES. WILL INCLUDE LOW CHANCE FOR POPS TO
ACCOMMODATE. WILL KEEP IT AS LIQUID RAINSHOWERS EVENTHOUGH 850MB
TEMPS ARE PROGGED TO DROP TO -2 ACROSS THIS AREA...HOWEVER THE
1000-850MB THICKNESSES ARE STILL PROGGED ABOVE 1300 THE USUAL
THICKNESS TO SEE FROZEN PCPN. FOR MAX/MIN TEMPS OPTED TO USE THE
LOWER END OF GUIDANCE DUE TO CAA ALREADY OCCURRING. WITH EXCELLENT
LOW LEVEL LAPSE RATES ESPECIALLY DURING THE INSOLATION PART OF THE
DAY...BROKEN TO OVERCAST STRATOCU WILL OVERSPREAD THE ILM CWA.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...COOL AND DRY WEATHER IS ON TAP FOR THE DURATION
OF THE SHORT TERM PERIOD. CUTOFF UPPER LOW WILL BE QUICKLY EXITING
TO THE NE ACRS NY AND INTO NEW ENGLAND STATES EARLY WED WITH
LINGERING VORT MAX IN THE TRAILING PART OF THE TROUGH OVER ARKANSAS.
THIS FEATURE WILL CUT TO OUR SOUTH WEDNESDAY EVENING. WITH THE LOW
LEVELS ADVECTING COOL AND DRY AIR HOWEVER THIS UPPER FEATURE WILL
HAVE LITTLE TO NO EFFECT ON SENSIBLE WEATHER. THIS LOW WILL DEEPEN
JUST OFF THE COAST OF THE CAROLINAS EARLY THURSDAY BUT WILL QUICKLY
ACQUIRE A NEGATIVE TILT ALLOWING FOR HEIGHT RISES OVER THE COASTAL
PLAIN TO MOVE IN FROM THE WEST BY THE AFTERNOON. THESE HEIGHT RISES
WILL NOT BE REALIZED AT THE SURFACE...NORMALLY IN THE FORM OF
WARMING TEMPERATURES. WEAK SURFACE HIGH ACROSS THE SOUTHEAST WILL
KEEP MIXING FAIRLY SHALLOW. BOTH DAYS WILL BRING HIGHS IN THE UPPER
50S AND LOWS IN THE LOW TO UPPER 30S...MILDEST ALONG THE COAST BY
NIGHT.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...LOW AMPLITUDE UPPER RIDGING CROSS THE AREA
FRIDAY AND SATURDAY WHILE SURFACE HIGH PRESSURE REMAINS TO OUR NNE.
THE LATTER WILL TEND TO OFFSET THE WARMING OF THE FORMER TO KEEP
TEMPS BELOW CLIMO. LARGE POSITIVELY TILTED TROUGHINESS DEVELOPS
OVER THE NORTH-CENTRAL PORTION OF THE COUNTRY FOR THE REMAINDER OF
THE PERIOD KEEPING THE AREA DRY. THE HIGH TO OUR NORTH SHOULD
PROGRESS TO THE EAST ENOUGH TO ALLOW FOR A SLIGHT MODERATION OF
TEMPS ESP BY MONDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 06Z...SCATTERED SHRA ACTIVITY CONTINUES TO SPREAD ACROSS
PORTIONS OF THE CWA AS DEPICTED BY CURRENT RADAR. ANTICIPATE THIS
TREND TO PERSIST...WITH RAINFALL COVERAGE INCREASING TO NEARLY
ENCOMPASS THE ENTIRE AREA AHEAD OF AN ADVANCING COLD FRONT.
SOUTHEAST WINDS WILL CONTINUE AOB 12KTS AT KILM FOR THE NEXT HOUR OR
SO...AND WEST WINDS AT THE KFLO/KLBT/KCRE/KMYR AOB 15KTS...WIND
GUSTS AOB 30 KTS.
CURRENT GUIDANCE AND FCST SOUNDINGS SUGGEST THE FROPA WILL OCCUR
THROUGH THE OVERNIGHT AS IT PROPAGATES WEST TO EAST. LOW CONFIDENCE
REGARDING EXACT TIMING OF PASSAGE...BUT EXPECT MVFR SHRA/TSRA...WITH
BRIEF PERIODS OF IFR IN HEAVIER DOWNPOURS TO CONTINUE. GIVEN LOW
INSTABILITY VALUES...THE PROBABILITY OF WIDESPREAD TSRA IS
UNLIKELY...HOWEVER CANNOT RULE OUT AN ISOLATED THUNDERSTORM. LOCAL
WRF MODEL SUGGESTS SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE
THROUGH THIS MORNING. AFTER 14Z APPROXIMATELY...ANTICIPATE
CONDITIONS TO IMPROVE TO VFR FOR REMAINDER OF VALID PERIOD...THOUGH
AREAS OF MVFR CIGS MAY STILL LINGER TUESDAY MID-MORNING. WINDS WILL
GRADUALLY SHIFT MORE WEST-SOUTHWEST LATER THIS MORNING...WITH
PERIODS OF GUSTY WINDS AOB 25KTS THROUGHOUT THE AFTERNOON INTO EARLY
EVENING.
EXTENDED OUTLOOK...EXPECT VFR THROUGH PERIOD.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 345 AM TUESDAY...SFC COLD FRONT HAS PUSHED ACROSS THE LOCAL
WATERS EARLY THIS MORNING. THE ENSUING CAA UNDER SW-W WINDS 15-25 KT
WITH FEW GUSTS 30-35 KT WILL RULE THE DAY. THE SFC PG IS PROGGED TO
RE-TIGHTEN BY MIDDAY ACROSS THE WATERS RESULTING IN SUSTAINED WIND
SPEEDS ON THE HIGHER SIDE OF THE RANGE GIVEN. THE RISEN SEAS WILL
PEAK EARLY THIS MORNING...THEN SLOWLY SUBSIDE TODAY THROUGH TONIGHT.
SOME OF THE HIGHER SEAS...ESPECIALLY THE OUTER WATERS OFF CAPE FEAR
AND ROMAIN...WERE AIDED BY SEAS BLEEDING IN FROM THE OFFSHORE WATERS
WHERE WINDS AT GALE FORCE OCCURRED. THE LOW MID 70S SSTS WERE THE
BIG CONTRIBUTOR FOR THESE HIGHER WINDS MAKING IT TO THE OFFSHORE
OCEAN SFC. SWAN GUIDANCE FOR SEAS WAS USED...BUT DID NOT LOWER THEM
AS FAST AS WHAT SWAN WAS INDICATING. THE SCA MAY NEED TO BE
EXTENDED FURTHER INTO TONIGHT...ESPECIALLY THE WATERS FROM CAPE FEAR
NORTHWARD. AVERAGE PERIODS WILL RUN 6-8 SECONDS THROUGH EARLY THIS
AFTERNOON. THE AVERAGE PERIODS WILL DECREASE TO 4 TO 6 SECONDS LATE
THIS AFTERNOON AND TONIGHT DUE TO WESTERLY WINDS ACROSS A DIMINISHED
FETCH AREA.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...WESTERLY WINDS ON WEDNESDAY WILL BE THE LAST
REMAINING EFFECTS OF THE PREVIOUS STORM SYSTEM...WHICH BY WED WILL
BE RAPIDLY MOVING INTO THE NEW ENGLAND STATES. WIND WILL THEN
TRANSITION OVER TO NORTHERLY LATE WEDNESDAY DUE TO HIGH PRESSURE
BUILDING IN FROM THE WEST. A FAIRLY ROBUST UPPER SYSTEM WILL CROSS
THE WATERS EARLY THURSDAY. POOR DIRECTIONAL ALIGNMENT OF WIND IN THE
VERTICAL HOWEVER WILL PREVENT THIS FROM MAKING MUCH OF A DIRECT
EFFECT/INCREASE IN SURFACE WIND SPEEDS. NO HEADLINES EXPECTED THIS
PERIOD FOR THE MOST PART. THE EXCEPTION MAY BE TOWARDS THE END OF
THE PERIOD WHEN SOME 5 FT SEAS MANAGE TO AFFECT THE VERY OUTER
REACHES OF THE 20NM FCST ZONE.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...N TO NE FLOW ON THE SOUTHEAST PERIPHERY OF HIGH
PRESSURE WILL CHARACTERIZE MOST OF THE PERIOD. WHILE WIND SPEED MAY
SHOW LITTLE VARIATION THOUGH THE PERIOD THE INCREASING TIME OF THE
STEADY FETCH COULD ADD SLIGHTLY TO WAVE HEIGHTS. 5 FT SEAS MAY
OCCASIONALLY BE AFFECTING THE OUTER PORTIONS OF MAINLY THE NORTHERN
ZONES. IT IS THUS HARD TO ASCERTAIN THE NEED FOR ANY CAUTIONARY
HEADLINES THIS FAR OUT IN TIME.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST TUESDAY FOR AMZ250-252-
254-256.
&&
$$
SYNOPSIS...MBB
NEAR TERM...DCH
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...SGL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
300 AM EST TUE NOV 29 2011
.SYNOPSIS...
COOLER AND DRIER AIR WILL BE USHERED IN FROM THE WEST TODAY. HIGH
PRESSURE WILL BUILD ACROSS THE EASTERN CAROLINAS FOR THE REMAINDER
OF THE WEEK. THIS HIGH WILL SHIFT OFF THE NORTHEAST COAST OVER THE
WEEKEND POSSIBLY ALLOWING FOR A SLIGHT MODERATION BACK TOWARDS
SEASONABLE TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
AS OF 1120 PM EST MONDAY...ADJUSTMENTS MADE TO PCPN COVERAGE AND
MOVEMENT ACROSS THE ILM CWA FOR THE REMAINDER OF THE OVERNIGHT. THE
2 DISTINCT BROKEN LINES OF CONVECTION EARLIER ARE MESHING INTO 1 AT
THE MOMENT. THE POTENTIAL SVR WX THREAT WILL OCCUR IMMEDIATELY ALONG
THE LINE OF CONVECTION THAT BASICALLY NOW BISECTS THE ILM CWA...FROM
CRE TO LBT. SMALL COUPLETS NOTED ON LOW LEVEL SRM...HOWEVER THEY
HAVE NOT BEEN STRONG OR TIGHT ENOUGH TO WORKS THEIR WAY TO THE SFC.
WIND THREAT OR TORNADO THREAT DUE TO DECENT LOW LEVEL WIND SHEAR
BOTH FROM DIRECTION AND VELOCITY...AS SEEN WITH 00Z TUE CHS RAOB
FLIGHT AND HODOGRAPHS. HAVE ADJUSTED PCPN MOVEMENTS BASED ON LATEST
RADAR MOSAIC TRENDS AND HRRR OUTPUT. WITH THIS INPUT...1/3 TO 1/2 OF
THE ILM CWA WILL STILL HAVE TO DEAL WITH PCPN BY DAYBREAK TUESDAY.
THE SEVERE WX THREAT ALONG THE LEADING EDGE OF THE CONVECTION WILL
HAVE MOVED NORTH AND EAST OF THE ILM CWA BY SUN-UP. BEST CAA AND
DRIER AIR TO OCCUR DURING THE DAY TUESDAY.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...COOL AND DRY WEATHER IS ON TAP FOR THE DURATION
OF THE SHORT TERM PERIOD. CUTOFF UPPER LOW WILL BE QUICKLY EXITING
TO THE NE ACRS NY AND INTO NEW ENGLAND STATES EARLY WED WITH
LINGERING VORT MAX IN THE TRAILING PART OF THE TROUGH OVER ARKANSAS.
THIS FEATURE WILL CUT TO OUR SOUTH WEDNESDAY EVENING. WITH THE LOW
LEVELS ADVECTING COOL AND DRY AIR HOWEVER THIS UPPER FEATURE WILL
HAVE LITTLE TO NO EFFECT ON SENSIBLE WEATHER. THIS LOW WILL DEEPEN
JUST OFF THE COAST OF THE CAROLINAS EARLY THURSDAY BUT WILL QUICKLY
ACQUIRE A NEGATIVE TILT ALLOWING FOR HEIGHT RISES OVER THE COASTAL
PLAIN TO MOVE IN FROM THE WEST BY THE AFTERNOON. THESE HEIGHT RISES
WILL NOT BE REALIZED AT THE SURFACE...NORMALLY IN THE FORM OF
WARMING TEMPERATURES. WEAK SURFACE HIGH ACROSS THE SOUTHEAST WILL
KEEP MIXING FAIRLY SHALLOW. BOTH DAYS WILL BRING HIGHS IN THE UPPER
50S AND LOWS IN THE LOW TO UPPER 30S...MILDEST ALONG THE COAST BY
NIGHT.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...LOW AMPLITUDE UPPER RIDGING CROSS THE AREA
FRIDAY AND SATURDAY WHILE SURFACE HIGH PRESSURE REMAINS TO OUR NNE.
THE LATTER WILL TEND TO OFFSET THE WARMING OF THE FORMER TO KEEP
TEMPS BELOW CLIMO. LARGE POSITIVELY TILTED TROUGHINESS DEVELOPS
OVER THE NORTH-CENTRAL PORTION OF THE COUNTRY FOR THE REMAINDER OF
THE PERIOD KEEPING THE AREA DRY. THE HIGH TO OUR NORTH SHOULD
PROGRESS TO THE EAST ENOUGH TO ALLOW FOR A SLIGHT MODERATION OF
TEMPS ESP BY MONDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 06Z...SCATTERED SHRA ACTIVITY CONTINUES TO SPREAD ACROSS
PORTIONS OF THE CWA AS DEPICTED BY CURRENT RADAR. ANTICIPATE THIS
TREND TO PERSIST...WITH RAINFALL COVERAGE INCREASING TO NEARLY
ENCOMPASS THE ENTIRE AREA AHEAD OF AN ADVANCING COLD FRONT.
SOUTHEAST WINDS WILL CONTINUE AOB 12KTS AT KILM FOR THE NEXT HOUR OR
SO...AND WEST WINDS AT THE KFLO/KLBT/KCRE/KMYR AOB 15KTS...WIND
GUSTS AOB 30 KTS.
CURRENT GUIDANCE AND FCST SOUNDINGS SUGGEST THE FROPA WILL OCCUR
THROUGH THE OVERNIGHT AS IT PROPAGATES WEST TO EAST. LOW CONFIDENCE
REGARDING EXACT TIMING OF PASSAGE...BUT EXPECT MVFR SHRA/TSRA...WITH
BRIEF PERIODS OF IFR IN HEAVIER DOWNPOURS TO CONTINUE. GIVEN LOW
INSTABILITY VALUES...THE PROBABILITY OF WIDESPREAD TSRA IS
UNLIKELY...HOWEVER CANNOT RULE OUT AN ISOLATED THUNDERSTORM. LOCAL
WRF MODEL SUGGESTS SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE
THROUGH THIS MORNING. AFTER 14Z APPROXIMATELY...ANTICIPATE
CONDITIONS TO IMPROVE TO VFR FOR REMAINDER OF VALID PERIOD...THOUGH
AREAS OF MVFR CIGS MAY STILL LINGER TUESDAY MID-MORNING. WINDS WILL
GRADUALLY SHIFT MORE WEST-SOUTHWEST LATER THIS MORNING...WITH
PERIODS OF GUSTY WINDS AOB 25KTS THROUGHOUT THE AFTERNOON INTO EARLY
EVENING.
EXTENDED OUTLOOK...EXPECT VFR THROUGH PERIOD.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1135 PM MONDAY...MID 70S SSTS LURKING JUST OFFSHORE FROM THE
ILM COASTAL WATERS...WITH 41013 AND 41004 BUOYS EXHIBITING THESE
WARMER WATER TEMPS. NEAR SHORE...LOW TO MID 60S REMAIN COMMON PER
LATEST OMRILM REPORTS. THE GRADIENT WINDS WILL FURTHER INCREASE
ACROSS ALL OF THE ILM WATERS THROUGH THE NIGHT REACHING STRONG SCA
CRITERIA. HOWEVER THE 40 TO 50 KT WINDS...IE. LOW LEVEL JET AT
925MB...ILLUSTRATED WELL BY THE LATEST KLTX VWP AND HRRR MODEL WILL
HAVE A DIFFICULT TIME REACHING THE OCEAN SFC...EVEN AS WIND
GUSTS...DUE TO THE COOLER SHELF WATERS. THESE HIGHER WINDS JUST OFF
THE DECK ARE LIKELY MAKING IT TO THE OCEAN SFC AS SUSTAINED AND/OR
WIND GUSTS ACROSS THE WARMER SSTS...VIA THE LATEST 41013 AND 41004
LATEST BUOY REPORTS. THE BIG KAHUNAS IN DC REMAIN VIGILANT AND
CONTINUE WITH THE GALE WARNING UP FOR THE OFFSHORE WATERS ADJACENT
TO THE ILM COASTAL WATERS.
HAVE INCREASED SEAS ACROSS THE ILM WATERS AND THE IMMEDIATE ADJACENT
OFFSHORE WATERS THROUGH THE TUESDAY PREDAWN HRS. WITH SIX TO 9 FT
BEING COMMON...EXCEPT UP TO 10-11 FT ACROSS THE SHALLOW OUTERWATERS
OFF CAPE FEAR. THE COLD FRONT...IDENTIFIED BY ENHANCED CONVECTION
JUST AHEAD OF IT...WILL TRACK ENE AND REACH THE WATERS BETWEEN SURF
CITY AND CAPE FEAR BY DAYBREAK. HAVE IDENTIFIED THE IMMEDIATE WIND
SWITCH FROM SE-S...THEN TO SW DURING THE DAY TUESDAY.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...WESTERLY WINDS ON WEDNESDAY WILL BE THE LAST
REMAINING EFFECTS OF THE PREVIOUS STORM SYSTEM...WHICH BY WED WILL
BE RAPIDLY MOVING INTO THE NEW ENGLAND STATES. WIND WILL THEN
TRANSITION OVER TO NORTHERLY LATE WEDNESDAY DUE TO HIGH PRESSURE
BUILDING IN FROM THE WEST. A FAIRLY ROBUST UPPER SYSTEM WILL CROSS
THE WATERS EARLY THURSDAY. POOR DIRECTIONAL ALIGNMENT OF WIND IN THE
VERTICAL HOWEVER WILL PREVENT THIS FROM MAKING MUCH OF A DIRECT
EFFECT/INCREASE IN SURFACE WIND SPEEDS. NO HEADLINES EXPECTED THIS
PERIOD FOR THE MOST PART. THE EXCEPTION MAY BE TOWARDS THE END OF
THE PERIOD WHEN SOME 5 FT SEAS MANAGE TO AFFECT THE VERY OUTER
REACHES OF THE 20NM FCST ZONE.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...N TO NE FLOW ON THE SOUTHEAST PERIPHERY OF HIGH
PRESSURE WILL CHARACTERIZE MOST OF THE PERIOD. WHILE WIND SPEED MAY
SHOW LITTLE VARIATION THOUGH THE PERIOD THE INCREASING TIME OF THE
STEADY FETCH COULD ADD SLIGHTLY TO WAVE HEIGHTS. 5 FT SEAS MAY
OCCASIONALLY BE AFFECTING THE OUTER PORTIONS OF MAINLY THE NORTHERN
ZONES. IT IS THUS HARD TO ASCERTAIN THE NEED FOR ANY CAUTIONARY
HEADLINES THIS FAR OUT IN TIME.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST TUESDAY FOR AMZ250-252-
254-256.
&&
$$
NEAR TERM...DCH/MJC
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...SGL
AREA FORECAST DISCUSSION...UPDATED
NWS NEWPORT/MOREHEAD CITY NC
1254 AM EST TUE NOV 29 2011
.SYNOPSIS...
A COLD FRONT WILL SWEEP THROUGH THE AREA TODAY FROM THE WEST.
HIGH PRESSURE WILL BUILD INTO NORTH CAROLINA WEDNESDAY THROUGH
THURSDAY. ANOTHER COLD FRONT WILL PASS THROUGH THE REGION FRIDAY
NIGHT. HIGH PRESSURE WILL ONCE AGAIN BUILD INTO THE AREA NEXT
WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 1250 AM TUES...EASTERN NORTH CAROLINA REMAINS PINCHED
BETWEEN HIGH PRESSURE NORTHEAST OF THE REGION AND A STRONG COLD
FRONT APPROACHING FROM THE WEST. THE NORTH TO SOUTH ORIENTED COLD
FRONT WILL BEGIN IMPACTING WESTERN ZONES DUPLIN COUNTY NORTH TO
PITT COUNTY BETWEEN 08-10Z WITH HEAVY SHOWERS WITH ISOLATED
THUNDER POSSIBLE. THREAT FOR SEVERE WEATHER REMAINS MINIMAL DUE TO
LACK OF INSTABILITY. SHEAR PROFILES ARE IMPRESSIVE WITH LLJ OF 35
KNOTS BASED ON LATEST LAPS SOUNDING. SOUTHEASTERLY WINDS WILL
CONTINUE 8-10 KNOTS WITH GUSTS UPWARDS OF 15 KNOTS DUE THE
PRESSURE GRADIENT. ONLY MINOR TWEAKS TO POPS/WX/TEMPS FOR THE
SHORT TERM EARLY MORNING UPDATE.
PREVIOUS DISCUSSION...MOIST SOUTHEASTERLY FLOW CONTINUES ACROSS THE
REGION THIS EVENING AHEAD OF A STRONG COLD FRONT PRESENTLY SLOWLY
MOVING ACROSS THE NC PIEDMONT AND INTO SERN NC WITH ASSOC UPPER
LOW SLOWLY PUSHING ACROSS NRN MS/AL AND S CNTRL TN. 00Z KMHX
SOUNDING SHOWS FAIRLY MOIST BELOW 800 MB BUT REMAINS DRY ABOVE
WITH PW`S SIMILAR TO THIS MORNING AROUND 0.85". DON`T THINK WE
WILL SEE MORE THAN AN ISOLATED LIGHT SHOWER THROUGH THE REMAINDER
OF THE EVENING WITH MOISTURE REMAINING SHALLOW. LATEST HRRR MODEL
RUN INDICATING STRONGER FORCING/HEAVIER PCPN PUSHING INTO DUPLIN
CO AROUND 3 AM AND TO NEAR A CAPE LOOKOUT TO GREENVILLE LINE BY 6
AM...WHICH IS CLOSE TO THE LEAD TIME OF ARRIVAL TOOLS.
AS THE FRONT MOVES EAST OVERNIGHT...LLJ WILL INC TO AOA 40 KT WITH
PWATS INC TO AROUND 1.5 INCHES. TREMENDOUS KINEMATICS WILL BE IN
PLACE WITH THE COLD FRONT...THOUGH LACKING INGREDIENT WILL BE
INSTABILITY. STILL...AN ISOLATED EMBEDDED STORM IS STILL POSSIBLE
AS FORCING WILL BE VERY STRONG... AND MAY PRODUCE LOCALLY DAMAGING
WIND GUSTS.
TEMPS THIS EVENING HAVE FALLEN INTO THE M/U60S AND DON`T EXPECT
THEM TO DROP MUCH MORE OVERNIGHT AS STRONG WAA PERSISTS AHEAD OF
THE FRONT...THE EXCEPTION BEING FAR WRN PORTION OF THE CWA WHERE
THE FRONT IS EXPECTED TO REACH BY 6 AM AND COULD SEE TEMPS FALLING
TO AROUND 60 AFTER FROPA.
&&
.SHORT TERM /TONIGHT/...
AS OF 3 PM MON...LINE OF SHOWERS WILL TRANSLATE EAST INTO THE
REST OF THE FA THROUGH THE MORNING ON TUE...REACHING THE OBX
AROUND THE NOON HOUR. AN ISO THUNDERSTORM WILL STILL BE
POSSIBLE...THOUGH STRONG CAA WILL LIMIT THE POTENTIAL FOR ANYTHING
MORE THAN AN ISO MENTION. DAYTIME HIGHS IN THE 60S WILL BE
REALIZED TUE MORNING...WITH TEMPS FALLING FROM WEST TO EAST
THROUGHOUT THE DAY BEHIND THE FROPA. BY AFTERNOON MANY AREAS WILL
HAVE DROPPED WELL INTO THE 50S. RAIN WILL CLEAR OUT FOR MOST AREAS
EXCEPT THE OBX BY EARLY AFTERNOON...WITH ONLY SOME SCT SHOWERS
REMAINING.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
CUTOFF LOW MOVES QUICKLY NORTH UP THE APPALACHIANS TUE NIGHT. WEAK
SFC RIDGE BUILDS ACROSS THE AREA TUE NIGHT IN THE WAKE OF COLD
FRONTAL PASSAGE. ANY LINGERING SHOWERS WILL BE ENDING OVER THE OUTER
BANKS EARLY TUE EVENING AS THE MID LEVEL DRYING MOVES TO THE COAST.
MUCH COOLER AIR WILL WORK INTO THE AREA AROUND THE DEPARTING UPPER
LOW WITH LOW TEMPS TUE NIGHT FALLING INTO THE 30S INLAND WITH
LOW-MID 40S AT THE COAST.
BELOW NORMAL TEMPERATURES WILL HIGHLIGHT THE WED THRU SAT TIMEFRAME
AS SEVERAL REINFORCING SHOTS OF COOLER AIR INVADE THE AREA. MOISTURE
WILL BE TOO SCARCE FOR ORGANIZED PCPN BUT MAY SEE CLOUDY INTERVALS
AS WEAK SHORT WAVES PASS THRU THE AREA.
TEMPERATURES WILL BEGIN TO MODERATE LATE IN THE WEEKEND AND INTO
EARLY NEXT WEEK AS RETURN FLOW GRADUALLY SETS UP AHEAD OF DOWNSTREAM
TROF. TIMING OF PCPN CHCS MAY BE TIED TO PROGRESSIVENESS OF LARGE
SCALE TROF BEING CARVED OUT OVER THE UPPER MIDWEST EARLY NEXT WEEK.
WILL KEEP THE DAY 7 FCST DRY FOR NOW UNTIL THE TIMING OF THIS
DOWNSTREAM FEATURE CAN BE BETTER RESOLVED.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
SHORT TERM /THROUGH TONIGHT/...
AS OF 1250 AM TUES...VFR CONDITIONS WILL DIMINISH TO IFR FROM
WEST TO EAST EARLY THIS MORNING ASSOCIATED WITH HEAVY SHOWERS
ALONG A STRONG NORTH TO SOUTH ORIENTED COLD FRONT PUSHING EAST
INTO EASTERN NC. OAJ/ISO WILL SEE LOWERED CEILINGS AND
VISIBILITIES BETWEEN 08-09Z FOLLOW SHORTLY BY PGV AND EWN. AWOS
ISSUES CONTINUE AT PGV SO WILL LIST AMENDMENT NOT SKED FOR PGV AT
THIS TIME. TAFS EXPECTED TO SEE 5-7 HOURS OF IFR CONDITIONS EARLY
THIS MORNING IMPROVING TO MVFR/VFR BY EARLY AFTERNOON. LOW CLOUDS
WILL LIFT AND BECOME BKN/OVC AROUND 5K FT BY LATE AFTERNOON...WITH
WINDS VEERING SOUTH THEN SOUTHWEST BEHIND THE FRONT.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
VFR CONDITIONS EXPECTED FOR A LARGE PART OF THIS FCST PERIOD AS
DRIER AIR FILTERS INTO THE REGION. MAY BE SOME CLOUDY INTERVALS DUE
TO WEAK SHORT WAVE PASSAGES BUT EXPECT CLOUD BASES WILL BE HIGHER
THAN 3K FT FOR THE MOST PART. MAY ALSO SEE BRIEF/PATCHY LATE
NIGHT/EARLY MORNING RADIATION FOG AS DEW POINT DEPRESSIONS LOWER
LATER IN THE WEEK.
&&
.MARINE...
SHORT TERM /THROUGH TUESDAY/...
AS OF 1250 AM TUES...LATEST SURFACE AND BUOY OBSERVATIONS INDICATE
SOUTHEAST WINDS 10 TO 20 KNOTS. SOUTHEAST WINDS WILL CONTINUE 15
TO 20 OVERNIGHT AND GUST UPWARDS OF 30 KNOTS...PER LATEST UPSTREAM
BUOY REPORT FROM FRYING PAN SHOALS. SEAS REMAIN 6-10 FT SOUTH OF
DIAMOND SHOALS WITH 3 TO 6 FT NORTH. NO SIGNIFICANT CHANGES TO THE
SHORT TERM FORECAST WITH THE MORNING UPDATE.
PREVIOUS DISCUSSION...WINDS AND SEAS GRADUALLY INCREASING THIS
EVENING AHEAD OF A STRONG COLD FRONT PRESENTLY PUSHING ACROSS SC.
FORECAST LOOKS ON TRACK WITH WINDS AROUND 15-20 KT SRN AND CENTRAL
WATERS AND 10-15 KT ELSEWHERE. SEAS ARE ALSO BUILDING ACROSS
SRN/CENTRAL WATERS WHERE BUOY 41036 NOW UP TO 8FT. GRADIENT INC
FURTHER AS THE STRONG COLD FRONT APPROACHES LATE TONIGHT...AND
WINDS AND SEAS WILL CONTINUE TO INC. SEAS WILL INC AND BUILD FROM
S TO N...WITH SCA CONDITIONS BEING MET FOR THE NORTHERN WATERS BY
EARLY TUE MORNING. KEPT SCA OUT OF THE SOUNDS FOR NOW...AS THE
COOLER WATERS SHOULD KEEP WINDS JUST BELOW THE 25 KT
THRESHOLD...THOUGH GUSTS MAY GET CLOSE TO THAT BY EARLY TUE
MORNING. WINDS WILL VEER FROM SE TO SW BEHIND THE COLD FRONT LATE
TUE MORNING THROUGH AFTERNOON.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
MODERATE (15-20KT) SW/W WINDS TUE NIGHT/WED WILL SHIFT MORE NW/N AT
ROUGHLY THE SAME SPEEDS AS WEAK SFC TROF PASSES ON THURSDAY. SEAS
WILL INITIALLY FALL BLO SMALL CRAFT ADVISORY LEVELS (6 FT) FOR A
TIME LATE WED/WED NIGHT BEFORE BUILDING BACK ABV 6 FT AGAIN AS WINDS
BECOME MORE NORTHERLY AND CONTINUE AT MODERATE LEVELS THU-SAT.
THEREFORE SMALL CRAFT ADVISORIES MAY AGAIN BE REQUIRED LATER IN THE
WEEK...MAINLY FOR SEAS.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST WEDNESDAY FOR AMZ152-154.
SMALL CRAFT ADVISORY UNTIL 4 PM EST WEDNESDAY FOR AMZ156-158.
SMALL CRAFT ADVISORY FROM 5 AM EARLY THIS MORNING TO 5 AM EST
WEDNESDAY FOR AMZ150.
&&
$$
SYNOPSIS...DAG
NEAR TERM...SK/DAG/TL
SHORT TERM...TL
LONG TERM...BTC
AVIATION...BTC/DAG
MARINE...BTC/DAG/SK/TL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1145 PM EST MON NOV 28 2011
.SYNOPSIS...
A STORM SYSTEM APPROACHING THE AREA FROM THE GULF COAST STATES WILL
BRING SHOWERS AND A FEW THUNDERSTORMS ACROSS THE AREA THROUGH
TUESDAY MORNING. THE ASSOCIATED COLD FRONT WILL PUSH THROUGH DURING
TUESDAY ALLOWING COOLER AND DRIER AIR TO INFILTRATE THE AREA IN ITS
WAKE. HIGH PRESSURE WILL BUILD ACROSS THE EASTERN CAROLINAS
WEDNESDAY THROUGH FRIDAY...THEN GIVE WAY TO THE NEXT DRY COLD
FRONTAL PASSAGE FRIDAY NIGHT. COOL HIGH PRESSURE WILL AFFECT THE
AREA THIS WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
AS OF 1120 PM EST MONDAY...ADJUSTMENTS MADE TO PCPN COVERAGE AND
MOVEMENT ACROSS THE ILM CWA FOR THE REMAINDER OF THE OVERNIGHT. THE
2 DISTINCT BROKEN LINES OF CONVECTION EARLIER ARE MESHING INTO 1 AT
THE MOMENT. THE POTENTIAL SVR WX THREAT WILL OCCUR IMMEDIATELY ALONG
THE LINE OF CONVECTION THAT BASICALLY NOW BISECTS THE ILM CWA...FROM
CRE TO LBT. SMALL COUPLETS NOTED ON LOW LEVEL SRM...HOWEVER THEY
HAVE NOT BEEN STRONG OR TIGHT ENOUGH TO WORKS THEIR WAY TO THE SFC.
WIND THREAT OR TORNADO THREAT DUE TO DECENT LOW LEVEL WIND SHEAR
BOTH FROM DIRECTION AND VELOCITY...AS SEEN WITH 00Z TUE CHS RAOB
FLIGHT AND HODOGRAPHS. HAVE ADJUSTED PCPN MOVEMENTS BASED ON LATEST
RADAR MOSAIC TRENDS AND HRRR OUTPUT. WITH THIS INPUT...1/3 TO 1/2 OF
THE ILM CWA WILL STILL HAVE TO DEAL WITH PCPN BY DAYBREAK TUESDAY.
THE SEVERE WX THREAT ALONG THE LEADING EDGE OF THE CONVECTION WILL
HAVE MOVED NORTH AND EAST OF THE ILM CWA BY SUN-UP. BEST CAA AND
DRIER AIR TO OCCUR DURING THE DAY TUESDAY.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...THE NAM...GFS AND ECMWF ARE IN FAIRLY GOOD
AGREEMENT WITH THE HANDLING TO THE CUT-OFF LOW AT 500 HPA THROUGH
48 HOURS. AFTER 48 HOURS...THE NAM`S REPRESENTATION OF THE SURFACE
LOW TRAILS THE OTHER MODELS AT 48H. AT THE SURFACE THESE THREE
MODELS ARE VERY SIMILAR WITH THE OCCLUDED LOW AS THEY MOVE THE LOW
FROM NORTHERN GEORGIA TO LAKE ERIE BY LATE WEDNESDAY NIGHT. BY 12
UTC TUESDAY...THE COLD FRONT AND ITS ASSOCIATED PRECIPITATION
SHIELD WILL BE OVER THE NORTHERN SECTIONS FOR THE FORECAST AREA
AND MOVING OUT OF THE AREA BEFORE NOON. AFTER THE FRONT SHIFTS
EAST-NORTHEASTWARD COOLER AIR WILL SPILL IN AND MAXIMUM
TEMPERATURES WILL STRUGGLE TO GET OUT OF THE UPPER 50S TO NEAR 60
ON TUESDAY AND ONLY IN THE UPPER 50S WEDNESDAY. LOW TEMPERATURES
ARE EXPECTED TO REMAIN IN THE MID TO UPPER 30S.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 3 PM MONDAY...SHORTWAVE WILL CROSS THE AREA THURS MORNING WITH
MID TO UPPER RIDGE BUILDING UP THE SOUTHEAST COAST LATE THURS
THROUGH SAT. AT THE SURFACE...HIGH PRESSURE WILL BUILD IN ON THURS.
THE CENTER OF HIGH WILL REMAIN WEST OF AREA WITH A DEEP NORTHERLY
FLOW OF COOL AND DRY AIR LASTING THROUGH SATURDAY. A WEAK MOISTURE
STARVED BOUNDARY MAY SLIDE SOUTH LATE FRI INTO EARLY SAT AS EVIDENT
IN MOISTURE AND WIND FIELDS BUT RIDGE BUILDING UP THE COAST MAY HOLD
IT OFF TO THE NORTH AND EAST AND OVERALL EFFECT WILL NOT BE MUCH.
MOISTURE WILL BE LIMITED AS PCP WATER VALUES WILL BE DOWN CLOSE TO A
QUARTER OF AN INCH WITH A SPIKE UP NEAR A HALF INCH AS FLOW COMES
AROUND FROM THE N-NW TO NE BY SAT NIGHT. OVERALL MAY SEE SOME CLOUDS
AS SHORTWAVE MOVES THROUGH ON THURS AND ASSOCIATED WITH BACK DOOR
FRONTAL BOUNDARY LATE FRI BUT NOT EXPECTING ANY PCP THROUGH THE
FIRST HALF OF THE WEEKEND AND SHOULD SEE A GOOD DEAL OF SUNSHINE.
GRADIENT RELAXES THROUGH THE WEEKEND AS HIGH PRESSURE EXTENDS DOWN
INTO THE CAROLINAS.
RIDGE SHIFTS OFF SHORE SUNDAY INTO MONDAY WITH A RETURN FLOW SETTING
UP ALOFT BUT THE SURFACE FLOW WILL BE A LITTLE SLOWER TO COME AROUND
AS CENTER OF HIGH SHIFTS OFF THE NEW ENGLAND COAST EARLY SUNDAY WITH
RIDGE EXTENDING SW DOWN INTO THE CAROLINAS MAINTAINING A NE TO E
FLOW THROUGH SUNDAY. BY MONDAY A DEEPER SOUTHERLY RETURN FLOW SETS
UP FROM THE SURFACE UP THROUGH THE MID TO UPPER LEVELS. PCP WATER
VALUES INCREASE THROUGH SUNDAY UP CLOSE TO THREE QUARTERS OF INCH
AND THEN UP TOWARDS 1.5 INCHES IN INCREASINGLY MOIST SOUTHERLY FLOW
LATE MONDAY INTO EARLY TUES AHEAD OF APPROACHING COLD FRONT.
AS FOR TEMPS...BEST CAA THROUGH THE PERIOD WILL COME IN DEEP
NORTHERLY FLOW ONCE SHORTWAVE CLEARS THE COAST ON THURS. H5 HEIGHTS
WILL INCREASE AS RIDGE BUILDS LATE THURS INTO THE WEEKEND. EXPECT
850 TEMPS TO DROP THURS WITH STEADY READINGS OR SLIGHT INCREASE
THEREAFTER. WITH PLENTY OF DRY AIR IN PLACE AND DEWPOINT TEMPS BELOW
40 IN MOST PLACES THURS THROUGH SUNDAY...EXPECT LARGER DIURNAL
SWINGS WITH TEMPS MAKING IT TO 55 TO CLOSE TO 60 FOR HIGHS AND DOWN
BELOW 40 MOST NIGHTS. WARMING TREND BEGINS EARLY NEXT WEEK WITH
TEMPS REBOUNDING CLOSER TO 70 BY MONDAY.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
AS OF 00Z...ISOLATED TO SCATTERED -SHRA ACTIVITY CONTINUES TO SPREAD
ACROSS WESTERN PORTIONS OF THE CWA AS DEPICTED BY CURRENT RADAR.
ANTICIPATE THIS TREND TO PERSIST OVER THE NEXT COUPLE OF
HOURS...WITH RAINFALL COVERAGE INCREASING ACROSS THE AREA AHEAD OF
AN ADVANCING COLD FRONT. SOUTHEAST WINDS WILL CONTINUE AOB
12KTS...WITH INCREASING WIND GUSTS AOB 25 KTS.
CURRENT GUIDANCE AND FCST SOUNDINGS SUGGEST THE FROPA WILL OCCUR
LATE TONIGHT INTO THE OVERNIGHT HOURS...AS IT PROPAGATES WEST TO
EAST. LOW CONFIDENCE REGARDING EXACT TIMING OF PASSAGE...BUT EXPECT
MVFR SHRA/TSRA...WITH PERIODS OF IFR POSSIBLE IN HEAVIER DOWNPOURS.
GIVEN LOW INSTABILITY VALUES...THE PROBABILITY OF WIDESPREAD TSRA IS
UNLIKELY...HOWEVER CANNOT RULE OUT ISOLATED CONVECTION...THUS HAVE
KEPT IN VCTS AND CB IN FCST. LOCAL WRF MODEL SUGGESTS SHOWERS AND
ISOLATED THUNDERSTORMS WILL CONTINUE THROUGH TUESDAY MORNING. AFTER
14Z APPROXIMATELY...ANTICIPATE CONDITIONS TO IMPROVE TO VFR FOR
REMAINDER OF VALID PERIOD...THOUGH AREAS OF MVFR CIGS MAY STILL
LINGER TUESDAY MID-MORNING. EXPECT WINDS TO GRADUALLY SHIFT MORE
WEST-SOUTHWEST TUESDAY MORNING...WITH PERIODS OF GUSTY WINDS AOB
20KTS.
EXTENDED OUTLOOK...EXPECT VFR THROUGH PERIOD.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1135 PM MONDAY...MID 70S SSTS LURKING JUST OFFSHORE FROM THE
ILM COASTAL WATERS...WITH 41013 AND 41004 BUOYS EXHIBITING THESE
WARMER WATER TEMPS. NEAR SHORE...LOW TO MID 60S REMAIN COMMON PER
LATEST OMRILM REPORTS. THE GRADIENT WINDS WILL FURTHER INCREASE
ACROSS ALL OF THE ILM WATERS THROUGH THE NIGHT REACHING STRONG SCA
CRITERIA. HOWEVER THE 40 TO 50 KT WINDS...IE. LOW LEVEL JET AT
925MB...ILLUSTRATED WELL BY THE LATEST KLTX VWP AND HRRR MODEL
...WILL HAVE A DIFFICULT TIME REACHING THE OCEAN SFC...EVEN AS WIND
GUSTS...DUE TO THE COOLER SHELF WATERS. THESE HIGHER WINDS JUST OFF
THE DECK ARE LIKELY MAKING IT TO THE OCEAN SFC AS SUSTAINED AND/OR
WIND GUSTS ACROSS THE WARMER SSTS...VIA THE LATEST 41013 AND 41004
LATEST BUOY REPORTS. THE BIG KAHUNAS IN DC REMAIN VIGILANT AND
CONTINUE WITH THE GALE WARNING UP FOR THE OFFSHORE WATERS ADJACENT
TO THE ILM COASTAL WATERS.
HAVE INCREASED SEAS ACROSS THE ILM WATERS AND THE IMMEDIATE ADJACENT
OFFSHORE WATERS THROUGH THE TUESDAY PREDAWN HRS. WITH SIX TO 9 FT
BEING COMMON...EXCEPT UP TO 10-11 FT ACROSS THE SHALLOW OUTERWATERS
OFF CAPE FEAR. THE COLD FRONT...IDENTIFIED BY ENHANCED CONVECTION
JUST AHEAD OF IT...WILL TRACK ENE AND REACH THE WATERS BETWEEN SURF
CITY AND CAPE FEAR BY DAYBREAK. HAVE IDENTIFIED THE IMMEDIATE WIND
SWITCH FROM SE-S...THEN TO SW DURING THE DAY TUESDAY.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...THE FORECAST PERIOD WILL BEGIN WITH THE SURFACE
COLD FRONT CROSSING THE WATERS AND WINDS BLOWING FROM WEST TO
SOUTHWEST AT 15 TO 20 KNOTS WITH A QUICK INCREASE IN WINDS WITH A
SHOT OF COLD AIR ADVECTION BY NIGHTFALL. SEAS ARE EXPECTED TO
REMAIN AT SMALL CRAFT CONDITIONS RANGE THROUGH TUESDAY NIGHT BEFORE
SLOWLY FALLING BELOW CRITERIA. WINDS WILL BE WESTERLY ON WEDNESDAY
AND WILL SHIFT TO THE NORTHWEST AS THE FINAL TROUGH FROM THE UPPER
LEVEL SYSTEM THAT PAST TO THE NORTHWEST OF THE WATERS ON TUESDAY.
LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 3 PM MONDAY...ONCE SHORTWAVE CLEARS THE WATERS ON
THURS...HIGH PRESSURE WILL BUILD IN WITH RIDGE BUILDING ALOFT
THROUGH THE PERIOD. OVERALL EXPECT DEEP COOL NORTHERLY FLOW
THROUGH MOST OF THE PERIOD. WINDS WILL VEER SLIGHTLY FROM N TO NE
BY SAT NIGHT AS CENTER OF HIGH PRESSURE SHIFTS OFF THE NEW ENGLAND
COAST. GRADIENT MAY RELAX LATE THURS THROUGH FRI AS ONE AREA OF
HIGH PRESSURE MOVES OFF SHORE BUT WILL TIGHTEN AGAIN FRI NIGHT
INTO SAT AS WEAK BACK DOOR FRONT MOVES SOUTH WITH SECOND AREA OF
HIGH PRESSURE BUILDING IN FOR SAT. THEREFORE NORTHERLY WINDS
AROUND 15 KTS ON THURS MAY DECREASE TO 10 TO 15 KTS BY FRI BEFORE
INCREASING AGAIN TO A SOLID 15 KTS IN THE OUTER WATERS FRI NIGHT
INTO SAT. THE ALONG SHORE WINDS WILL CREATE HIGHER SEAS OFF SHORE
THROUGH THE PERIOD. EXPECT SEAS CLOSER TO 1 TO 2 FT NEAR SHORE AND
3 TO 4 OUTER WATERS WITH SOME 5 FOOTERS CREEPING IN SAT MORNING IN
NORTHERLY SURGE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST TUESDAY FOR AMZ250-252-
254-256.
&&
$$
NEAR TERM...DCH/MJC
SHORT TERM...HAWKINS
LONG TERM...RGZ
AVIATION...SGL
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1253 PM EST TUE NOV 29 2011
.SYNOPSIS...
LOW PRESSURE WILL MOVE ACROSS THIS AFTERNOON AND TONIGHT. SOME LIGHT
RAIN AND SNOW SHOWERS THROUGH EARLY WEDNESDAY MORNING. HIGH PRESSURE
THURSDAY. MOISTURE STARVED FRONT FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
915 AM UPDATE. NEW COMMA SHAPED AREA OF RAIN HAS QUICKLY DEVELOPED
OVER SOUTHERN THIRD OF CWA IN RESPONSE TO YET ANOTHER IMPULSE
ROTATING AROUND APPROACHING UPPER LOW OVER THE TENNESSEE VALLEY.
THIS WILL SHIFT NORTH THIS MORNING AND MAINLY BE NORTH OF OUR CWA BY
EARLY AFTERNOON. HAVE UPPED POPS WITH THIS FEATURE THRU EARLY
AFTERNOON. THEN...PER CURRENT FORECAST...SHOWERS DEVELOP LATER THIS
AFTERNOON UNDER THE UPPER LOW. ALSO TWEAKED TEMPS DOWNWARD PER
CURRENT TEMPS AND TRENDS UPSTREAM.
PREVIOUS DISCUSSION BELOW...
FRONT AS 0830Z HAD JUST PASSED UNI-3I2-CRW-BKW LINE...WITH BRIEF GUSTS
NEAR 25KTS ON NARROW ELEVATED CONVECTIVE BAND. HAVE OCCLUDED FRONT
CLEARING CENTRAL LOWLANDS NEXT HR AND SE OH/NORTHERN WV LOWLANDS BY
12Z. BOUNDARY TAKES ON MORE OF A NW TO SE ORIENTATION IN THE
MTNS...HENCE A FEW HRS DELAY OF FROPA FROM TO S TO N. DRY SLOT
QUICKLY WORKS IN THRU MID MORNING...EFFECTIVELY SHUTTING OFF PCPN
AFTER A COUPLE HRS POST FRONTAL RAINS. THIS MAY LINGER LONGER ACROSS
SE OH AND THE NORTHERN AREAS DUE TO LAGGING NATURE OF BOUNDARY
ACROSS MTNS AND INTO VA. RAINFALL AMOUNTS TO HALF AN INCH LOOK GOOD
WITH THIS...WITH UP TO AN INCH ALONG EAST FACING SLOPES IN MTNS.
REWORKED HRLY TEMPERATURE GRIDS TDY FROM LAV AND RUC TO REFLECT MILD
READINGS AHEAD OF BOUNDARY EARLY THIS MORNING AND DROPPING TMPS WITH FROPA.
LOOKING AT A MIDNIGHT HIGH FOR ALL PLACES...WITH TEMPS DROPPING
10-15 DEGREES WITH FROPA...AND SLOWLY FALLING THROUGH 40S TDY...WITH
30S ACROSS THE HIGH TERRAIN.
DEEP UPR LOW WILL TRACK THRU EASTERN KY THIS AFTN AND INTO THE AREA
THIS EVENING. THIS WILL INCREASE THE MOISTURE DEPTH AND LIFT TO
ALLOW LIGHT PCPN TO BREAK OUT LATE THIS AFTN ACROSS SE KY AND INTO
SOUTHERN AREAS THIS EVENING BEFORE ROTATING UP THE SPINE OF MTNS
TONIGHT. DRY SLOT MAY PIVOT ARND INTO SE OH...KEEPING AREAS ALONG
AND WEST OF OH RVR DRY INTO THE EARLY PART OF THE NIGHT...BEFORE
FILLING IN TOWARD MORNING.
AREA WILL SEE THE BEST UPR LOW HAS TO OFFER WITH RESPECT TO
MAGNITUDE OF COLD POOL ALOFT. H85 TMPS BOTTOM OUT TO ARN -5C BY 12Z
WED. A MONTH FROM NOW...THERE WOULD BE NO CONCERN ABOUT PCPN TYPE
OUTSIDE OF MTNS. HOWEVER...AS IT STANDS....BL WILL BE SLOW TO COOL
THIS EVENING. MDLS SHOW BL TEMPS AND H925 TMPS WARM ENOUGH TO KEEP
THINGS LIQUID OUTSIDE OF THE MTNS UNTIL AFTER MIDNIGHT...IF NOT A
LITTLE LONGER. EVEN IN MTNS...WHERE IT SHOULD BE COLD ENOUGH FOR
SNOW...KEEP ACCUMULATIONS TO ARND AN INCH OR SO IN THE AOA
3KFT...DUE TO VERY WET AND WARM GRND. WITH SATURATION/WEAK LIFT TO NEAR
-8C...WILL KEEP DZ MENTION OUT OF GRIDS ATTM.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
MODELS SHOW SOME LINGERING MOISTURE ON WEDNESDAY. 850 MB
TEMPERATURES ARE NOT COLD ENOUGH FOR AUTO CONVECTION IN THE LOWER
LAYER...SO WILL KEEP POPS ON THE LOW SIDE. BASED ON 850 MB
TEMPERATURES AND WITH SOME CLEARING IN THE WESTERN COUNTIES DURING
THE DAY WEDNESDAY...MOS GUIDANCE IN THE WEST LOOKS A BIT TOO COLD.
HIGH PRESSURE THEN BUILDS IN FOR THURSDAY. A MOISTURE STARVED FRONT
ARRIVES ON FRIDAY...BUT BASED ON LACK OF MOISTURE IN THE
MODELS...WILL KEEP A DRY FORECAST FOR NOW.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
HAVE GONE WITH HPC THINKING FOR THIS PART OF THE FORECAST...WHICH
LEANS TOWARDS THE ECMWF/UKMET/CANADIAN SOLUTIONS. LATEST 12 UTC
GFS MODEL HAS TRENDED TOWARDS THESE SOLUTIONS AS WELL.
A WEAK COLD FRONT WILL PUSH THROUGH THE AREA ON FRIDAY. HOWEVER...
THE AIRMASS WILL BE QUITE DRY...SO NO PRECIP IS EXPECTED WITH THIS
FEATURE. HIGH PRESSURE WILL THEN BE IN CONTROL FOR SATURDAY AND
SATURDAY NIGHT...BEFORE A COLD FRONT APPROACHES FROM THE WEST
SUNDAY. THE FRONT IS EXPECTED TO BE IN THE AREA ON MONDAY.
AS A RESULT...EXPECT PRECIP CHANCES WILL INCREASE BY LATE
SUNDAY...WITH CHANCES CONTINUING THROUGH THE END OF THE PERIOD.
ONLY REAL CHANGES FROM HPC THINKING WERE THE SKY GRIDS. FELT HPC
FORECAST INCLUDED TOO MANY CLOUDS WITH DRY FRONT ON FRIDAY...SO
TWEAKED DOWNWARD.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
UPPER LOW MOVES ACROSS THE AREA TONIGHT AND WEDNESDAY MORNING.
GENERALLY WIDESPREAD MVFR CEILINGS...IFR MOUNTAINS AFTER 02Z. SCATTERED
RAIN SHOWERS CAN BE EXPECTED AT ANY TIME UNDER THE COLD POOL...BUT
MOST ORGANIZED AREA OF SHOWERS WILL BE OVER THE MOUNTAINS 00Z-06Z
AND OVER SOUTHEAST OHIO 06Z TO 12Z. RAIN SHOWERS WILL CHANGE TO SNOW
SHOWERS MOUNTAINS ABOVE 200 FEET BY 02Z AND A MIX OF RAIN AND SNOW
SHOWERS ELSEWHERE 06Z TO 12Z. IFR CEILINGS IN HEAVIER SHOWERS AND
MOUNTAINS.
AFTER 12Z WHILE SHOWERS DECREASE FROM WEST TOE EAST...MVFR CEILINGS
PREVAIL LOWLANDS...WITH IFR MOUNTAINS.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z WEDNESDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING OF ORGANIZED AREAS OF SHOWERS AND
IMPROVEMENT ON WEDNESDAY MAY VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00
CRW CONSISTENCY L M M H M M L M M M M M
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H L M M L L L L L
EKN CONSISTENCY H H M M M L M L L L M M
PKB CONSISTENCY H L M M M H M M M M M H
CKB CONSISTENCY L M M M M M H M M M M M
AFTER 18Z WEDNESDAY...
IFR STILL POSSIBLE IN MOUNTAIN RAIN AND SNOW SHOWERS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JSH/RPY/30
NEAR TERM...JMV
SHORT TERM...RPY
LONG TERM...JSH
AVIATION...JMV
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
930 AM EST TUE NOV 29 2011
.SYNOPSIS...
LOW PRESSURE WILL MOVE ACROSS TODAY. SOME LIGHT PRECIPITATION THROUGH
TONIGHT. HIGH PRESSURE THURSDAY. MOISTURE STARVED FRONT FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
915 AM UPDATE. NEW COMMA SHAPED AREA OF RAIN HAS QUICKLY DEVELOPED
OVER SOUTHERN THIRD OF CWA IN RESPONSE TO YET ANOTHER IMPULSE
ROTATING AROUND APPROACHING UPPER LOW OVER THE TENNESSEE VALLEY.
THIS WILL SHIFT NORTH THIS MORNING AND MAINLY BE NORTH OF OUR CWA BY
EARLY AFTERNOON. HAVE UPPED POPS WITH THIS FEATURE THRU EARLY
AFTERNOON. THEN...PER CURRENT FORECAST...SHOWERS DEVELOP LATER THIS
AFTERNOON UNDER THE UPPER LOW. ALSO TWEAKED TEMPS DOWNWARD PER
CURRENT TEMPS AND TRENDS UPSTREAM.
PREVIOUS DISCUSSION BELOW...
FRONT AS 0830Z HAD JUST PASSED UNI-3I2-CRW-BKW LINE...WITH BRIEF GUSTS
NEAR 25KTS ON NARROW ELEVATED CONVECTIVE BAND. HAVE OCCLUDED FRONT
CLEARING CENTRAL LOWLANDS NEXT HR AND SE OH/NORTHERN WV LOWLANDS BY
12Z. BOUNDARY TAKES ON MORE OF A NW TO SE ORIENTATION IN THE
MTNS...HENCE A FEW HRS DELAY OF FROPA FROM TO S TO N. DRY SLOT
QUICKLY WORKS IN THRU MID MORNING...EFFECTIVELY SHUTTING OFF PCPN
AFTER A COUPLE HRS POST FRONTAL RAINS. THIS MAY LINGER LONGER ACROSS
SE OH AND THE NORTHERN AREAS DUE TO LAGGING NATURE OF BOUNDARY
ACROSS MTNS AND INTO VA. RAINFALL AMOUNTS TO HALF AN INCH LOOK GOOD
WITH THIS...WITH UP TO AN INCH ALONG EAST FACING SLOPES IN MTNS.
REWORKED HRLY TEMPERATURE GRIDS TDY FROM LAV AND RUC TO REFLECT MILD
READINGS AHEAD OF BOUNDARY EARLY THIS MORNING AND DROPPING TMPS WITH FROPA.
LOOKING AT A MIDNIGHT HIGH FOR ALL PLACES...WITH TEMPS DROPPING
10-15 DEGREES WITH FROPA...AND SLOWLY FALLING THROUGH 40S TDY...WITH
30S ACROSS THE HIGH TERRAIN.
DEEP UPR LOW WILL TRACK THRU EASTERN KY THIS AFTN AND INTO THE AREA
THIS EVENING. THIS WILL INCREASE THE MOISTURE DEPTH AND LIFT TO
ALLOW LIGHT PCPN TO BREAK OUT LATE THIS AFTN ACROSS SE KY AND INTO
SOUTHERN AREAS THIS EVENING BEFORE ROTATING UP THE SPINE OF MTNS
TONIGHT. DRY SLOT MAY PIVOT ARND INTO SE OH...KEEPING AREAS ALONG
AND WEST OF OH RVR DRY INTO THE EARLY PART OF THE NIGHT...BEFORE
FILLING IN TOWARD MORNING.
AREA WILL SEE THE BEST UPR LOW HAS TO OFFER WITH RESPECT TO
MAGNITUDE OF COLD POOL ALOFT. H85 TMPS BOTTOM OUT TO ARN -5C BY 12Z
WED. A MONTH FROM NOW...THERE WOULD BE NO CONCERN ABOUT PCPN TYPE
OUTSIDE OF MTNS. HOWEVER...AS IT STANDS....BL WILL BE SLOW TO COOL
THIS EVENING. MDLS SHOW BL TEMPS AND H925 TMPS WARM ENOUGH TO KEEP
THINGS LIQUID OUTSIDE OF THE MTNS UNTIL AFTER MIDNIGHT...IF NOT A
LITTLE LONGER. EVEN IN MTNS...WHERE IT SHOULD BE COLD ENOUGH FOR
SNOW...KEEP ACCUMULATIONS TO ARND AN INCH OR SO IN THE AOA
3KFT...DUE TO VERY WET AND WARM GRND. WITH SATURATION/WEAK LIFT TO NEAR
-8C...WILL KEEP DZ MENTION OUT OF GRIDS ATTM.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
MODELS SHOW SOME LINGERING MOISTURE ON WEDNESDAY. 850 MB
TEMPERATURES ARE NOT COLD ENOUGH FOR AUTO CONVECTION IN THE LOWER
LAYER...SO WILL KEEP POPS ON THE LOW SIDE. BASED ON 850 MB
TEMPERATURES AND WITH SOME CLEARING IN THE WESTERN COUNTIES DURING
THE DAY WEDNESDAY...MOS GUIDANCE IN THE WEST LOOKS A BIT TOO COLD.
HIGH PRESSURE THEN BUILDS IN FOR THURSDAY. A MOISTURE STARVED FRONT
ARRIVES ON FRIDAY...BUT BASED ON LACK OF MOISTURE IN THE
MODELS...WILL KEEP A DRY FORECAST FOR NOW.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
HAVE GONE WITH HPC THINKING FOR THIS PART OF THE FORECAST...WHICH
LEANS TOWARDS THE ECMWF/UKMET/CANADIAN SOLUTIONS. LATEST 12 UTC
GFS MODEL HAS TRENDED TOWARDS THESE SOLUTIONS AS WELL.
A WEAK COLD FRONT WILL PUSH THROUGH THE AREA ON FRIDAY. HOWEVER...
THE AIRMASS WILL BE QUITE DRY...SO NO PRECIP IS EXPECTED WITH THIS
FEATURE. HIGH PRESSURE WILL THEN BE IN CONTROL FOR SATURDAY AND
SATURDAY NIGHT...BEFORE A COLD FRONT APPROACHES FROM THE WEST
SUNDAY. THE FRONT IS EXPECTED TO BE IN THE AREA ON MONDAY.
AS A RESULT...EXPECT PRECIP CHANCES WILL INCREASE BY LATE
SUNDAY...WITH CHANCES CONTINUING THROUGH THE END OF THE PERIOD.
ONLY REAL CHANGES FROM HPC THINKING WERE THE SKY GRIDS. FELT HPC
FORECAST INCLUDED TOO MANY CLOUDS WITH DRY FRONT ON FRIDAY...SO
TWEAKED DOWNWARD.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
15Z TUESDAY THRU 12Z WEDNESDAY...
UPDATED TO INCREASE SHOWERS CENTRAL AND NORTH THRU EARLY AFTERNOON
WITH IMPULSE ROTATING NORTH NORTHWEST AROUND APPROACHING UPPER LOW
OVER THE TENNESSEE VALLEY. EXPECT MVFR TO IFR IN THIS AREA OF RAIN
SHOWERS.
PREVIOUS DISCUSSION...
BEHIND THE FRONT...GENERALLY MVFR CEILINGS PREVAIL WITH A COUPLE HRS
OF POST FRONTAL RAINS AS WINDS TURNING TO SOUTH SOUTHWEST. DRY SLOT
WORKS IN THRU MID MORNING...ESSENTIALLY ENDING PCPN FOLLOWING POST
FRONTAL RAINS. NOT COLD ENOUGH YET FOR SNOW EXCEPT POSSIBLY IN
SOUTHERN MOUNTAIN RIDGETOPS AFTER 16Z WITH NO ACCUMULATION.
UPR LOW ROTATES THRU THIS AFTN. MOISTURE DEPTH INCREASE UNDER COLD
POOL WHICH SHOULD ALLOW SHOWERY PCPN TO BREAK OUT ACROSS THE AREA
THIS EVENING. AS LLVL TEMPS CONT TO COOL...A TRANSITION TO SHSN IS
EXPECTED ACROSS THE MTNS. BRING BACK MVFR CIGS THIS AFTN UNDER
COLD POOL...WITH IFR CONDITIONS MTNS AMID DEVELOPING SHSN.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY...
FORECAST CONFIDENCE: HIGH TO MEDIUM.
ALTERNATE SCENARIOS: TIMING OF OCCLUDED FRONT AND LOWER CEILINGS
WITH BAND OF RAIN SHOWERS MAY VARY. DOWNSLOPING EFFECTS MAY KEEP
KCKB AND KEKN VFR AHEAD OF FRONT. VARYING CIGS POST FRONTAL.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
EST 1HRLY 09 10 11 12 13 14 15 16 17 18 19 20
CRW CONSISTENCY M H H H L H H M H H H M
HTS CONSISTENCY M M H H H H H H H H M M
BKW CONSISTENCY M M M L H H H H M M M M
EKN CONSISTENCY M H H H H M L L H H M M
PKB CONSISTENCY H M M L M H M M H H H H
CKB CONSISTENCY M H H M M L L M H H H H
AFTER 12Z WEDNESDAY...
IFR POSSIBLE IN RAIN AND SNOW LATE TUE INTO WED...MAINLY MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JSH/RPY/30
NEAR TERM...JMV
SHORT TERM...RPY
LONG TERM...JSH
AVIATION...JMV
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
609 AM EST TUE NOV 29 2011
.SYNOPSIS...
LOW PRESSURE WILL MOVE ACROSS TODAY. SOME LIGHT PRECIPITATION
TONIGHT. HIGH PRESSURE THURSDAY. MOISTURE STARVED FRONT FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATED...
FCST ON TRACK...NO CHANGES ATTM.
PREVIOUS DISCUSSION BELOW...
FRONT AS 0830Z HAD JUST PASSED UNI-3I2-CRW-BKW LINE...WITH BRIEF GUSTS
NEAR 25KTS ON NARROW ELEVATED CONVECTIVE BAND. HAVE OCCLUDED FRONT
CLEARING CENTRAL LOWLANDS NEXT HR AND SE OH/NORTHERN WV LOWLANDS BY
12Z. BOUNDARY TAKES ON MORE OF A NW TO SE ORIENTATION IN THE
MTNS...HENCE A FEW HRS DELAY OF FROPA FROM TO S TO N. DRY SLOT
QUICKLY WORKS IN THRU MID MORNING...EFFECTIVELY SHUTTING OFF PCPN
AFTER A COUPLE HRS POST FRONTAL RAINS. THIS MAY LINGER LONGER ACROSS
SE OH AND THE NORTHERN AREAS DUE TO LAGGING NATURE OF BOUNDARY
ACROSS MTNS AND INTO VA. RAINFALL AMOUNTS TO HALF AN INCH LOOK GOOD
WITH THIS...WITH UP TO AN INCH ALONG EAST FACING SLOPES IN MTNS.
REWORKED HRLY TEMPERATURE GRIDS TDY FROM LAV AND RUC TO REFLECT MILD
READINGS AHEAD OF BOUNDARY EARLY THIS MORNING AND DROPPING TMPS WITH FROPA.
LOOKING AT A MIDNIGHT HIGH FOR ALL PLACES...WITH TEMPS DROPPING
10-15 DEGREES WITH FROPA...AND SLOWLY FALLING THROUGH 40S TDY...WITH
30S ACROSS THE HIGH TERRAIN.
DEEP UPR LOW WILL TRACK THRU EASTERN KY THIS AFTN AND INTO THE AREA
THIS EVENING. THIS WILL INCREASE THE MOISTURE DEPTH AND LIFT TO
ALLOW LIGHT PCPN TO BREAK OUT LATE THIS AFTN ACROSS SE KY AND INTO
SOUTHERN AREAS THIS EVENING BEFORE ROTATING UP THE SPINE OF MTNS
TONIGHT. DRY SLOT MAY PIVOT ARND INTO SE OH...KEEPING AREAS ALONG
AND WEST OF OH RVR DRY INTO THE EARLY PART OF THE NIGHT...BEFORE
FILLING IN TOWARD MORNING.
AREA WILL SEE THE BEST UPR LOW HAS TO OFFER WITH RESPECT TO
MAGNITUDE OF COLD POOL ALOFT. H85 TMPS BOTTOM OUT TO ARN -5C BY 12Z
WED. A MONTH FROM NOW...THERE WOULD BE NO CONCERN ABOUT PCPN TYPE
OUTSIDE OF MTNS. HOWEVER...AS IT STANDS....BL WILL BE SLOW TO COOL
THIS EVENING. MDLS SHOW BL TEMPS AND H925 TMPS WARM ENOUGH TO KEEP
THINGS LIQUID OUTSIDE OF THE MTNS UNTIL AFTER MIDNIGHT...IF NOT A
LITTLE LONGER. EVEN IN MTNS...WHERE IT SHOULD BE COLD ENOUGH FOR
SNOW...KEEP ACCUMULATIONS TO ARND AN INCH OR SO IN THE AOA
3KFT...DUE TO VERY WET AND WARM GRND. WITH SATURATION/WEAK LIFT TO NEAR
-8C...WILL KEEP DZ MENTION OUT OF GRIDS ATTM.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
MODELS SHOW SOME LINGERING MOISTURE ON WEDNESDAY. 850 MB
TEMPERATURES ARE NOT COLD ENOUGH FOR AUTO CONVECTION IN THE LOWER
LAYER...SO WILL KEEP POPS ON THE LOW SIDE. BASED ON 850 MB
TEMPERATURES AND WITH SOME CLEARING IN THE WESTERN COUNTIES DURING
THE DAY WEDNESDAY...MOS GUIDANCE IN THE WEST LOOKS A BIT TOO COLD.
HIGH PRESSURE THEN BUILDS IN FOR THURSDAY. A MOISTURE STARVED FRONT
ARRIVES ON FRIDAY...BUT BASED ON LACK OF MOISTURE IN THE
MODELS...WILL KEEP A DRY FORECAST FOR NOW.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
HAVE GONE WITH HPC THINKING FOR THIS PART OF THE FORECAST...WHICH
LEANS TOWARDS THE ECMWF/UKMET/CANADIAN SOLUTIONS. LATEST 12 UTC
GFS MODEL HAS TRENDED TOWARDS THESE SOLUTIONS AS WELL.
A WEAK COLD FRONT WILL PUSH THROUGH THE AREA ON FRIDAY. HOWEVER...
THE AIRMASS WILL BE QUITE DRY...SO NO PRECIP IS EXPECTED WITH THIS
FEATURE. HIGH PRESSURE WILL THEN BE IN CONTROL FOR SATURDAY AND
SATURDAY NIGHT...BEFORE A COLD FRONT APPROACHES FROM THE WEST
SUNDAY. THE FRONT IS EXPECTED TO BE IN THE AREA ON MONDAY.
AS A RESULT...EXPECT PRECIP CHANCES WILL INCREASE BY LATE
SUNDAY...WITH CHANCES CONTINUING THROUGH THE END OF THE PERIOD.
ONLY REAL CHANGES FROM HPC THINKING WERE THE SKY GRIDS. FELT HPC
FORECAST INCLUDED TOO MANY CLOUDS WITH DRY FRONT ON FRIDAY...SO
TWEAKED DOWNWARD.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
LOW PRESSURE LIFTS NORTH OUT OF AREA TDY.
OCCLUDED FRONT WORKING ACROSS THE AREA THRU 13Z. ELEVATED
CONVECTIVE BAND MAY PRODUCE BRIEF IFR CIGS/VSBY. HAVE CODED UP
SOME TEMPO GROUPS TO HANDLE THIS IT MOVES ACROSS NORTHERN SITES
12-14Z. DOWNSLOPING EFFECTS COULD MITIGATE THIS FOR KEKN AND KCKB.
BEHIND THE FRONT...GENERALLY MVFR CEILINGS PREVAIL WITH A COUPLE
HRS OF POST FRONTAL RAINS AS WINDS TURNING TO SOUTH SOUTHWEST. DRY
SLOT WORKS IN THRU MID MORNING...ESSENTIALLY ENDING PCPN FOLLOWING
POST FRONTAL RAINS. NOT COLD ENOUGH YET FOR SNOW EXCEPT POSSIBLY
IN SOUTHERN MOUNTAIN RIDGETOPS AFTER 16Z WITH NO ACCUMULATION.
UPR LOW ROTATES THRU THIS AFTN. MOISTURE DEPTH INCREASE UNDER COLD
POOL WHICH SHOULD ALLOW SHOWERY PCPN TO BREAK OUT ACROSS THE AREA
THIS EVENING. AS LLVL TEMPS CONT TO COOL...A TRANSITION TO SHSN IS
EXPECTED ACROSS THE MTNS. BRING BACK MVFR CIGS THIS AFTN UNDER
COLD POOL...WITH IFR CONDITIONS MTNS AMID DEVELOPING SHSN.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY...
FORECAST CONFIDENCE: HIGH TO MEDIUM.
ALTERNATE SCENARIOS: TIMING OF OCCLUDED FRONT AND LOWER CEILINGS
WITH BAND OF RAIN SHOWERS MAY VARY. DOWNSLOPING EFFECTS MAY KEEP
KCKB AND KEKN VFR AHEAD OF FRONT. VARYING CIGS POST FRONTAL.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22
EST 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
CRW CONSISTENCY M M H H M H H H H H H H
HTS CONSISTENCY M H M M M M H M H M M M
BKW CONSISTENCY H H H H H H M L H M M H
EKN CONSISTENCY M M M M H H L M H H H H
PKB CONSISTENCY M L M L H M L H H H H H
CKB CONSISTENCY M L M M M M M L H H H H
AFTER 12Z WEDNESDAY...
IFR POSSIBLE IN RAIN AND SNOW LATE TUE INTO WED...MAINLY MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JSH/RPY/30
NEAR TERM...30
SHORT TERM...RPY
LONG TERM...JSH
AVIATION...30
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
408 AM EST TUE NOV 29 2011
.SYNOPSIS...
LOW PRESSURE WILL MOVE ACROSS TODAY. SOME LIGHT PRECIPITATION
TONIGHT. HIGH PRESSURE THURSDAY. MOISTURE STARVED FRONT FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
FRONT AS 0830Z HAD JUST PASSED UNI-3I2-CRW-BKW LINE...WITH BRIEF GUSTS
NEAR 25KTS ON NARROW ELEVATED CONVECTIVE BAND. HAVE OCCLUDED FRONT
CLEARING CENTRAL LOWLANDS NEXT HR AND SE OH/NORTHERN WV LOWLANDS BY
12Z. BOUNDARY TAKES ON MORE OF A NW TO SE ORIENTATION IN THE
MTNS...HENCE A FEW HRS DELAY OF FROPA FROM TO S TO N. DRY SLOT
QUICKLY WORKS IN THRU MID MORNING...EFFECTIVELY SHUTTING OFF PCPN
AFTER A COUPLE HRS POST FRONTAL RAINS. THIS MAY LINGER LONGER ACROSS
SE OH AND THE NORTHERN AREAS DUE TO LAGGING NATURE OF BOUNDARY
ACROSS MTNS AND INTO VA. RAINFALL AMOUNTS TO HALF AN INCH LOOK GOOD
WITH THIS...WITH UP TO AN INCH ALONG EAST FACING SLOPES IN MTNS.
REWORKED HRLY TEMPERATURE GRIDS TDY FROM LAV AND RUC TO REFLECT MILD
READINGS AHEAD OF BOUNDARY EARLY THIS MORNING AND DROPPING TMPS WITH FROPA.
LOOKING AT A MIDNIGHT HIGH FOR ALL PLACES...WITH TEMPS DROPPING
10-15 DEGREES WITH FROPA...AND SLOWLY FALLING THROUGH 40S TDY...WITH
30S ACROSS THE HIGH TERRAIN.
DEEP UPR LOW WILL TRACK THRU EASTERN KY THIS AFTN AND INTO THE AREA
THIS EVENING. THIS WILL INCREASE THE MOISTURE DEPTH AND LIFT TO
ALLOW LIGHT PCPN TO BREAK OUT LATE THIS AFTN ACROSS SE KY AND INTO
SOUTHERN AREAS THIS EVENING BEFORE ROTATING UP THE SPINE OF MTNS
TONIGHT. DRY SLOT MAY PIVOT ARND INTO SE OH...KEEPING AREAS ALONG
AND WEST OF OH RVR DRY INTO THE EARLY PART OF THE NIGHT...BEFORE
FILLING IN TOWARD MORNING.
AREA WILL SEE THE BEST UPR LOW HAS TO OFFER WITH RESPECT TO
MAGNITUDE OF COLD POOL ALOFT. H85 TMPS BOTTOM OUT TO ARN -5C BY 12Z
WED. A MONTH FROM NOW...THERE WOULD BE NO CONCERN ABOUT PCPN TYPE
OUTSIDE OF MTNS. HOWEVER...AS IT STANDS....BL WILL BE SLOW TO COOL
THIS EVENING. MDLS SHOW BL TEMPS AND H925 TMPS WARM ENOUGH TO KEEP
THINGS LIQUID OUTSIDE OF THE MTNS UNTIL AFTER MIDNIGHT...IF NOT A
LITTLE LONGER. EVEN IN MTNS...WHERE IT SHOULD BE COLD ENOUGH FOR
SNOW...KEEP ACCUMULATIONS TO ARND AN INCH OR SO IN THE AOA
3KFT...DUE TO VERY WET AND WARM GRND. WITH SATURATION/WEAK LIFT TO NEAR
-8C...WILL KEEP DZ MENTION OUT OF GRIDS ATTM.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
MODELS SHOW SOME LINGERING MOISTURE ON WEDNESDAY. 850 MB
TEMPERATURES ARE NOT COLD ENOUGH FOR AUTO CONVECTION IN THE LOWER
LAYER...SO WILL KEEP POPS ON THE LOW SIDE. BASED ON 850 MB
TEMPERATURES AND WITH SOME CLEARING IN THE WESTERN COUNTIES DURING
THE DAY WEDNESDAY...MOS GUIDANCE IN THE WEST LOOKS A BIT TOO COLD.
HIGH PRESSURE THEN BUILDS IN FOR THURSDAY. A MOISTURE STARVED FRONT
ARRIVES ON FRIDAY...BUT BASED ON LACK OF MOISTURE IN THE
MODELS...WILL KEEP A DRY FORECAST FOR NOW.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
HAVE GONE WITH HPC THINKING FOR THIS PART OF THE FORECAST...WHICH
LEANS TOWARDS THE ECMWF/UKMET/CANADIAN SOLUTIONS. LATEST 12 UTC
GFS MODEL HAS TRENDED TOWARDS THESE SOLUTIONS AS WELL.
A WEAK COLD FRONT WILL PUSH THROUGH THE AREA ON FRIDAY. HOWEVER...
THE AIRMASS WILL BE QUITE DRY...SO NO PRECIP IS EXPECTED WITH THIS
FEATURE. HIGH PRESSURE WILL THEN BE IN CONTROL FOR SATURDAY AND
SATURDAY NIGHT...BEFORE A COLD FRONT APPROACHES FROM THE WEST
SUNDAY. THE FRONT IS EXPECTED TO BE IN THE AREA ON MONDAY.
AS A RESULT...EXPECT PRECIP CHANCES WILL INCREASE BY LATE
SUNDAY...WITH CHANCES CONTINUING THROUGH THE END OF THE PERIOD.
ONLY REAL CHANGES FROM HPC THINKING WERE THE SKY GRIDS. FELT HPC
FORECAST INCLUDED TOO MANY CLOUDS WITH DRY FRONT ON FRIDAY...SO
TWEAKED DOWNWARD.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
LOW PRESSURE LIFTS NORTH THRU KENTUCKY TONIGHT.
OCCLUDED FRONT WORKING ACROSS THE AREA THRU 12Z. ELEVATED
CONVECTIVE BAND MAY PRODUCE BRIEF IFR CIGS/VSBY ALONG WITH GUSTS
TO 30KTS. HAVE CODED UP SOME TEMPO GROUPS TO HANDLE THIS IT MOVES
N THRU AREA 06-12Z. COULD SEE SOME HIGHER GUSTS ACROSS RIDGE TOPS
GIVEN 50KT LLVL JET.
BEHIND THE FRONT...GENERALLY MVFR CEILINGS PREVAIL WITH A COUPLE
HRS OF POST FRONTAL RAINS AS WINDS TURNING TO SOUTH SOUTHWEST. DRY
SLOT WORKS IN THRU MID MORNING...ESSENTIALLY ENDING PCPN FOLLOWING
POST FRONTAL RAINS. NOT COLD ENOUGH YET FOR SNOW EXCEPT POSSIBLY
IN SOUTHERN MOUNTAIN RIDGETOPS AFTER 14Z WITH NO ACCUMULATION.
UPR LOW ROTATES THRU THIS AFTN. MOISTURE DEPTH INCREASE UNDER COLD
POOL WHICH SHOULD ALLOW SHOWERY PCPN TO BREAK OUT ACROSS THE AREA.
AS LLVL TEMPS CONT TO COOL...A TRANSITION TO SHSN IS EXPECTED
ACROSS THE MTNS. BRING BACK MVFR CIGS THIS AFTN UNDER COLD
POOL...WITH IFR CONDITIONS MTNS AMID DEVELOPING SHSN.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY...
FORECAST CONFIDENCE: HIGH TO MEDIUM.
ALTERNATE SCENARIOS: TIMING OF OCCLUDED FRONT AND LOWER CEILINGS
WITH BAND OF RAIN SHOWERS MAY VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE TUE 11/29/11
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EST 1HRLY 01 02 03 04 05 06 07 08 09 10 11 12
CRW CONSISTENCY H H H M H H M H H H M M
HTS CONSISTENCY M L L M M M L M M M M M
BKW CONSISTENCY M M M M L L L L L M M M
EKN CONSISTENCY M M M M M H M L L L L L
PKB CONSISTENCY H H L H H M L M M L L M
CKB CONSISTENCY H H H H H M M H H L L M
AFTER 06Z WEDNESDAY...
IFR POSSIBLE IN RAIN AND SNOW LATE TUE INTO WED...MAINLY MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JSH/RPY/30
NEAR TERM...30
SHORT TERM...RPY
LONG TERM...JSH
AVIATION...30
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
126 AM EST TUE NOV 29 2011
.SYNOPSIS...
LOW PRESSURE TO OUR SOUTHWEST WILL MOVE TO PENNSYLVANIA BY LATE
TUESDAY. SOME LINGERING PRECIPITATION POSSIBLE WEDNESDAY...INCLUDING
SNOW SHOWERS. HIGH PRESSURE THURSDAY.
&&
.NEAR TERM /THROUGH TODAY/...
UPDATED...
FCST REMAINDER OF OVERNIGHT HRS GENERALLY ON TRACK. DID SPEED UP
FROPA A FEW HRS BASED ON LATEST RUC. FRONT AS 06Z HAD JUST PASSED
ILN-HTS-I16...WITH BRIEF GUSTS NEAR 30KTS ON NARROW ELEVATED
CONVECTIVE BAND. HAVE OCCLUDED FRONT CLEARING CENTRAL LOWLANDS BY
09Z AND SE OH/NORTHERN WV LOWLANDS BY 12Z. BOUNDARY TAKES ON MORE
OF A NW TO SE ORIENTATION IN THE MTNS...HENCE A FEW HRS DELAY OF
FROPA FROM TO S TO N. DRY SLOT QUICKLY WORKS IN THRU MID
MORNING...EFFECTIVELY SHUTTING OFF PCPN AFTER A COUPLE HRS POST
FRONTAL RAINS. THIS MAY LINGER LONGER ACROSS SE OH AND THE
NORTHERN AREAS DUE TO LAGGING NATURE OF BOUNDARY ACROSS MTNS AND
INTO VA. RAINFALL AMNTS HALF AN INCH LOOK GOOD WITH THIS...WITH UP
TO AN INCH ACROSS SE OH AND NORTHERN AREAS. COULD SEE LCLY HIGHER
AMNTS IN MTNS AND ESPECIALLY EAST FACING SLOPES.
REWORKED HRLY TMP GRIDS FROM LAV AND RUC TO REFLECT MILD READINGS
AHEAD OF BOUNDARY AND DROPPING TMPS WITH FROPA.
PREVIOUS DISCUSSION BELOW...
HI RES MODELS AND EVEN THE GFS ARE IN QUITE GOOD AGREEMENT ON THE
EVOLUTION OF THE IMPRESSIVE UPPER LOW AND ASSOCIATED SURFACE
FEATURES LIFTING NORTHEASTWARD ACROSS OUR REGION TONIGHT AND
TUESDAY. ITS ASSOCIATED SURFACE LOW OVER GEORGIA AT 18Z TODAY WILL
BECOME VERTICALLY STACKED UNDER THE UPPER LOW...DRIVING AN
OCCLUDED FRONT BEFORE IT. THIS OCCLUDED FRONT WILL LIKELY REACH A
DAY-HTS-BLF LINE AROUND 08Z...THEN EXIT INTO PENNSYLVANIA BY 14Z
TUESDAY. SOME INTENSIFICATION OF THIS SYSTEM IS NOTED ON ALL THE
MODELS.
THIS SCENARIO HAS A WELL SUPPORTED AND DYNAMIC OCCLUDED FRONT MOVING
ACROSS US TONIGHT. ONE IMPORTANT FEATURE WILL BE THE STRENGTHENING
SOUTHEASTERLY FLOW AHEAD OF THE FRONT...WITH 850 MB SPEEDS OF AROUND
55 KTS. HOWEVER...NOCTURNAL TIMING OF THE WINDS AND WARM ADVECTION
SUGGESTS WINDS STRONG ENOUGH FOR WIND ADVISORY CRITERIA WILL STAY
MAINLY ON THE MOUNTAIN RIDGETOPS. THUS...WILL HIGHLIGHT STRONG AND
GUSTY WINDS FOR RIDGETOPS AND NOT GO WITH AN ADVISORY AT TIME.
SECOND FEATURE WILL BE A WELL ORGANIZED BAND OF HEAVIER RAIN SHOWERS
PRECEDING THE OCCLUDED FRONT...ESPECIALLY EAST FACING SLOPES OF
MOUNTAINS AND WEST OF THE OHIO RIVER WHERE DOWNSLOPING IS LESS OF A
FACTOR. EXPECT RAINFALL AMOUNTS WITH THE FRONT TO RANGE FROM A HALF
TO THREE QUARTERS OF AN INCH IN THE RELATIVE RAIN SHADOW JUST WEST
OF THE MOUNTAINS...TO POSSIBLY AN INCH AND A QUARTER OVER SOUTHEAST
OHIO AND PARTS OF THE MOUNTAINS. DO NOT THINK THIS IS ENOUGH TO GO
WITH A FLOOD WATCH AS PREVIOUS 24 HOUR RAINS HAVE BEEN HALF AN INCH
TO AN INCH AT BEST OVER SOUTHEAST OHIO AND LITTLE ELSEWHERE.
BEHIND THE FRONT WILL BE A RELATIVE DRY SLOT WITH PERHAPS SCATTERED
LIGHT RAIN SHOWERS. LACK OF LOW LEVEL COLD AIR SUGGESTS ANY SHOWERS
BEHIND THE FRONT WILL MAINLY REMAIN AS LIQUID. THERE MAY BE SOME WET
FLAKES OF SNOW OVER THE HIGHER MOUNTAINS LATER ON TUESDAY AS THIS
IS WHERE THE COLD AIR ALOFT WILL ARRIVE FIRST. NO ACCUMULATION.
LOOK FOR TEMPS TO ONLY SLOWLY DROP WITH THE PRECIP TONIGHT...THEN
REMAIN RELATIVELY STEADY TO ONLY A SLIGHT RECOVERY BEHIND THE FRONT
ON TUESDAY. COLD CORE ALOFT WILL BRING AN INCREASED AREA OF SHOWERS
MAINLY OVER EASTERN SECTIONS TUESDAY AFTERNOON...AND HAVE RAISED
POPS ACCORDINGLY. STILL...DOWNPLAYING SNOW TUESDAY DUE TO RELATIVELY
WARM BOUNDARY LAYER TEMPS.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
STRONG LOW ALOFT DEEPENS AS IT LIFTS NORTH TUESDAY NIGHT WITH A
CHILLIER AIRMASS NOW HAVING FILLED IN. UPPER LEVELS WILL HAVE SINCE
DRIED OUT...LEAVING LOW AND MID LEVEL MOISTURE AND WEAK FORCING
UNTIL THE SYSTEM CLEARS THE CWA. BULK OF THE LIQUID EQUIVALENT
PRECIPITATION ACCUMULATIONS SHOULD BE OVER BY TUESDAY NIGHT AND
WEDNESDAY. SNOW SHOWERS NOT OUT OF THE QUESTION IN THE LOWLANDS
TUESDAY NIGHT...BUT UNLIKELY TO SEE ANY ACCUMULATIONS HERE AS A
TRANSITION TO LIQUID IS LIKELY WEDNESDAY. IN THE HIGHER ELEVATIONS
OF THE EASTERN MOUNTAINS WHERE THE TEMPERATURES WILL HAVE A BETTER
CHANCE OF STAYING BELOW FREEZING...LIGHT ACCUMULATIONS ARE POSSIBLE
THROUGH THE DURATION OF THE SHORT TERM FORECAST.
PRESSURE RISES COMMENCE WEDNESDAY NIGHT INTO THURSDAY WITH HIGH
PRESSURE SETTLING IN...BUT THE NORTHWEST FLOW SHOULD KEEP THE LIGHT
SNOW SHOWERS GOING IN THE NORTHEAST MOUNTAINS UNTIL 06Z THURSDAY.
CLEAR SKIES FOLLOW FOR THE BULK OF THURSDAY WITH THE HIGH
PRESSURE...LESS SOME CIRRUS ADVECTION LATER IN THE DAY. COULD SEE
SOME OF THE COLDEST AIR OF THE SEASON AREA WIDE WEDNESDAY NIGHT WITH
LOW TO MID 20S AREA WIDE...AND EVEN TEENS IN THE MOUNTAINS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
HAVE GONE WITH HPC THINKING FOR THIS PART OF THE FORECAST...WHICH
LEANS TOWARDS THE ECMWF/UKMET/CANADIAN SOLUTIONS. LATEST 12 UTC
GFS MODEL HAS TRENDED TOWARDS THESE SOLUTIONS AS WELL.
A WEAK COLD FRONT WILL PUSH THROUGH THE AREA ON FRIDAY. HOWEVER...
THE AIRMASS WILL BE QUITE DRY...SO NO PRECIP IS EXPECTED WITH THIS
FEATURE. HIGH PRESSURE WILL THEN BE IN CONTROL FOR SATURDAY AND
SATURDAY NIGHT...BEFORE A COLD FRONT APPROACHES FROM THE WEST
SUNDAY. THE FRONT IS EXPECTED TO BE IN THE AREA ON MONDAY.
AS A RESULT...EXPECT PRECIP CHANCES WILL INCREASE BY LATE
SUNDAY...WITH CHANCES CONTINUING THROUGH THE END OF THE PERIOD.
ONLY REAL CHANGES FROM HPC THINKING WERE THE SKY GRIDS. FELT HPC
FORECAST INCLUDED TOO MANY CLOUDS WITH DRY FRONT ON FRIDAY...SO
TWEAKED DOWNWARD.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
LOW PRESSURE LIFTS NORTH THRU KENTUCKY TONIGHT.
OCCLUDED FRONT WORKING ACROSS THE AREA THRU 12Z. ELEVATED
CONVECTIVE BAND MAY PRODUCE BRIEF IFR CIGS/VSBY ALONG WITH GUSTS
TO 30KTS. HAVE CODED UP SOME TEMPO GROUPS TO HANDLE THIS IT MOVES
N THRU AREA 06-12Z. COULD SEE SOME HIGHER GUSTS ACROSS RIDGE TOPS
GIVEN 50KT LLVL JET.
BEHIND THE FRONT...GENERALLY MVFR CEILINGS PREVAIL WITH A COUPLE
HRS OF POST FRONTAL RAINS AS WINDS TURNING TO SOUTH SOUTHWEST. DRY
SLOT WORKS IN THRU MID MORNING...ESSENTIALLY ENDING PCPN FOLLOWING
POST FRONTAL RAINS. NOT COLD ENOUGH YET FOR SNOW EXCEPT POSSIBLY
IN SOUTHERN MOUNTAIN RIDGETOPS AFTER 14Z WITH NO ACCUMULATION.
UPR LOW ROTATES THRU THIS AFTN. MOISTURE DEPTH INCREASE UNDER COLD
POOL WHICH SHOULD ALLOW SHOWRY PCPN TO BREAK OUT ACROSS THE AREA.
AS LLVL TEMPS CONT TO COOL...A TRANSITION TO SHSN IS EXPECTED
ACROSS THE MTNS. BRING BACK MVFR CIGS THIS AFTN UNDER COLD
POOL...WITH IFR CONDITIONS MTNS AMID DEVELOPING SHSN.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY...
FORECAST CONFIDENCE: HIGH TO MEDIUM.
ALTERNATE SCENARIOS: TIMING OF OCCLUDED FRONT AND LOWER CEILINGS
WITH BAND OF RAIN SHOWERS MAY VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE TUE 11/29/11
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EST 1HRLY 01 02 03 04 05 06 07 08 09 10 11 12
CRW CONSISTENCY H H H M H H M H H H M M
HTS CONSISTENCY M L L M M M L M M M M M
BKW CONSISTENCY M M M M L L L L L M M M
EKN CONSISTENCY M M M M M H M L L L L L
PKB CONSISTENCY H H L H H M L M M L L M
CKB CONSISTENCY H H H H H M M H H L L M
AFTER 06Z WEDNESDAY...
IFR POSSIBLE IN RAIN AND SNOW LATE TUE INTO WED...MAINLY MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...26/JSH/JMV
NEAR TERM...JMV/30
SHORT TERM...26
LONG TERM...JSH
AVIATION...30
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1053 PM EST WED NOV 30 2011
.SYNOPSIS...
HIGH PRESSURE OVER THE OHIO VALLEY WILL BUILD INTO PENNSYLVANIA TONIGHT
AND THURSDAY. A MOISTURE STARVED COLD FRONT WILL PUSH SOUTHEAST THROUGH
THE AREA ON FRIDAY FOLLOWED ANOTHER HIGH PRESSURE SYSTEM FOR THE
WEEKEND. A SLOW MOVING COLD FRONT WILL LIKELY PUSH THROUGH THE
AREA EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
LATE EVENING WATER VAPOR LOOP SHOWS UPPER LVL TROF AXIS EXITING
EASTERN PA. SUBSIDENCE/LOWERING INVERSION HGTS IN THE WAKE OF
THIS FEATURE ARE PRODUCING CLEARING SKIES ACROSS MOST OF CENTRAL
PA. HOWEVER...SOME PERSISTENT STRATOCU REMAIN BANKED ALONG THE
WEST SLOPES OF THE ALLEGHENIES. LATEST NAM 925MB RH FIELDS SUGGEST
PATCHY CLOUDS COULD LINGER OVR THE W MTNS THRU MUCH OF THE NIGHT.
ELSEWHERE...CLEARING SKIES AND DIMINISHING WINDS OVERNIGHT...AS
HIGH PRESSURE BUILDS IN. CAN/T RULE OUT SOME PATCHY VALLEY FOG
TOWARD DAWN ACROSS THE NW MTNS...WHERE HRRR DATA INDICATING A CALM
WIND AND NR 100PCT RH BY 12Z. TEMPS WILL BE MUCH CHILLIER THAN
RECENT NIGHTS...DROPPING BACK INTO THE 20S IN MOST AREAS.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
HIGH PRESSURE OVER THE OHIO VALLEY WILL DOMINATE OUR WX
THURSDAY...PROVIDING CENTRAL PA WITH MAINLY SUNNY SKIES AND MILD
TEMPS. A BIT OF CIRRUS ASSOC WITH SHORTWAVE OVR THE N PLAINS COULD
FILTER THE SUNSHINE AT TIMES...ESP NORTH. HOWEVER...ON BALANCE IT
SHOULD BE A SUNNY DAY. 18Z GEFS MEAN 850 TEMPS ARND 1C SHOULD
SUPPORT HIGHS FROM THE L40S MTNS...TO ARND 50F OVR THE LOWER SUSQ
VALLEY. THESE READINGS ARE STILL SEVERAL DEGREES ABV NORMAL FOR
THE FIRST DAY OF DECEMBER.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
NOT A LOT OF CHANGE FROM YESTERDAY. MAINLY DRY CONDITIONS INTO
SUNDAY. THERE COULD BE A SHOWER ON FRIDAY AND SUNDAY...BUT NOT
MUCH MOISTURE TO WORK WITH.
INTERESTING THING TODAY IS VISIBLE SATELLITE PICTURE...SHOWING
STRIP OF SNOW FROM SOUTHERN ONTARIO INTO MI. THIS HAS HELPED
EDGE TEMPS DOWN SOME NORTH AND WEST OF THE LAKES THIS AFT.
COLDEST AIR IN OUR CWA OVERHEAD NOW. THUS FOR NOW...LEFT MIN
TEMPS ON THE LOW SIDE FOR THU NIGHT AND FRIDAY NIGHT...GIVEN
SOURCE OF OUR COLD AIR.
MAIN CHANGE WAS MONDAY INTO WED...MODELS HINT THAT THE NEXT
MAJOR SYSTEM MAY CUT OFF...MUCH LIKE WHAT WE SAW WITH THE
CURRENT SYSTEM. THUS COLD AIR MAY NOT COME IN MUCH BEFORE
TUESDAY NIGHT OR WED...INSTEAD OF LATE MONDAY AND TUE. THUS
ADJUSTED EXTENT OF SNOW SHOWERS AND TEMPS ON THIS PACKAGE
TO TAKE THIS INTO ACCOUNT.
AFTER THIS...SIGNS OF ANOTHER WARM UP...AS MODELS KEEP
BUILDING HIGH HEIGHTS OVER THE SE STATES BY 12/10.
&&
.AVIATION /04Z THURSDAY THROUGH MONDAY/...
AN UPPER LEVEL TROF LIFTING AWAY FROM THE REGION WILL GIVE WAY TO
HIGH PRESSURE AT THE SURFACE A ALOFT. DRIER AIR AND WEAKENING
UPSLOPE WESTERLY FLOW WILL CONTINUE THE IMPROVING CONDITIONS.
EXPECT MVFR CIGS REMAINING AT THE HIGHEST ELEVATION AIRFIELDS
BFD/JST AND UNV...SHOULD IMPROVE TO VFR BY MIDNIGHT...JOINING ALL
OTHER SITES. SKIES SHOULD THEN BECOME MAINLY CLEAR AT ALL SITES
OVERNIGHT WITH DECREASING WINDS.
OUTLOOK...
THU...VFR. NO SIG WX.
FRI...POSSIBLE MVFR NW WITH SNOW SHOWERS. VFR ELSEWHERE.
SAT AND SUN...VFR...MVFR CIGS POSSIBLE LATE SUN OVER THE WEST.
MON...MVFR/IFR WITH SCATTERED RAIN SHOWERS.
&&
.HYDROLOGY...
A FLASH FLOOD WATCH IS IN EFFECT FOR THE AREA DIRECTLY DOWNSTREAM
FROM THE SPEEDWELL DAM IN LANCASTER COUNTY. THE SPILLWAY WAS
DAMAGED DURING HEAVY RAINS EARLIER THIS FALL WHICH HAVE CAUSED
WATER BEHIND THE DAM TO BUILD UP TO DANGEROUS LEVELS. LOCAL
EMERGENCY MANAGERS WILL CONTINUE TO MONITOR THE SITUATION.
LATEST INFORMATION FROM THE COUNTY HAS NOTED WATER LEVELS
SLOWLY COMING DOWN.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR PAZ066.
&&
$$
SYNOPSIS...FITZGERALD/LA CORTE
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD/LA CORTE
LONG TERM...MARTIN
AVIATION...LA CORTE/GARTNER
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
808 PM EST WED NOV 30 2011
.SYNOPSIS...
HIGH PRESSURE OVER THE OHIO VALLEY WILL BUILD INTO PENNSYLVANIA TONIGHT
AND THURSDAY. A MOISTURE STARVED COLD FRONT WILL PUSH SOUTHEAST THROUGH
THE AREA ON FRIDAY FOLLOWED ANOTHER HIGH PRESSURE SYSTEM FOR THE
WEEKEND. A SLOW MOVING COLD FRONT WILL LIKELY PUSH THROUGH THE
AREA EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
EVENING WATER VAPOR LOOP SHOWING UPPER LVL TROF AXIS OVR CENTRAL
PA. SUBSIDENCE/LOWERING INVERSION HGTS IN THE WAKE OF THIS FEATURE
WILL PRODUCE CLEARING SKIES ACROSS CENTRAL PA WITHIN THE NEXT FEW
HOURS /OCCURRING MOST QUICKLY DOWNWIND OR EAST OF THE MTNS/. CLEARING
SKIES AND APPROACH OF HIGH PRESSURE WILL CAUSE THE WINDS TO DIE
DOWN. CAN/T RULE OUT SOME PATCHY VALLEY FOG TOWARD DAWN ACROSS
THE NW MTNS...WHERE HRRR DATA INDICATING A CALM WIND AND NR 100PCT
RH BY 12Z. TEMPS WILL BE MUCH CHILLIER THAN RECENT NIGHTS...DROPPING
BACK INTO THE 20S IN MOST AREAS.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
HIGH PRESSURE OVER THE OHIO VALLEY WILL DOMINATE OUR WX
THURSDAY...PROVIDING CENTRAL PA WITH MAINLY SUNNY SKIES AND MILD
TEMPS. A BIT OF CIRRUS ASSOC WITH SHORTWAVE OVR THE N PLAINS COULD
FILTER THE SUNSHINE AT TIMES...ESP NORTH. HOWEVER...ON BALANCE IT
SHOULD BE A SUNNY DAY. 18Z GEFS MEAN 850 TEMPS ARND 1C SHOULD
SUPPORT HIGHS FROM THE L40S MTNS...TO ARND 50F OVR THE LOWER SUSQ
VALLEY. THESE READINGS ARE STILL SEVERAL DEGREES ABV NORMAL FOR
THE FIRST DAY OF DECEMBER.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
NOT A LOT OF CHANGE FROM YESTERDAY. MAINLY DRY CONDITIONS INTO
SUNDAY. THERE COULD BE A SHOWER ON FRIDAY AND SUNDAY...BUT NOT
MUCH MOISTURE TO WORK WITH.
INTERESTING THING TODAY IS VISIBLE SATELLITE PICTURE...SHOWING
STRIP OF SNOW FROM SOUTHERN ONTARIO INTO MI. THIS HAS HELPED
EDGE TEMPS DOWN SOME NORTH AND WEST OF THE LAKES THIS AFT.
COLDEST AIR IN OUR CWA OVERHEAD NOW. THUS FOR NOW...LEFT MIN
TEMPS ON THE LOW SIDE FOR THU NIGHT AND FRIDAY NIGHT...GIVEN
SOURCE OF OUR COLD AIR.
MAIN CHANGE WAS MONDAY INTO WED...MODELS HINT THAT THE NEXT
MAJOR SYSTEM MAY CUT OFF...MUCH LIKE WHAT WE SAW WITH THE
CURRENT SYSTEM. THUS COLD AIR MAY NOT COME IN MUCH BEFORE
TUESDAY NIGHT OR WED...INSTEAD OF LATE MONDAY AND TUE. THUS
ADJUSTED EXTENT OF SNOW SHOWERS AND TEMPS ON THIS PACKAGE
TO TAKE THIS INTO ACCOUNT.
AFTER THIS...SIGNS OF ANOTHER WARM UP...AS MODELS KEEP
BUILDING HIGH HEIGHTS OVER THE SE STATES BY 12/10.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
AN UPPER LEVEL TROF LIFTING AWAY FROM THE REGION WILL GIVE WAY TO
HIGH PRESSURE AT THE SURFACE A ALOFT. DRIER AIR AND WEAKENING
UPSLOPE WESTERLY FLOW WILL CONTINUE THE IMPROVING CONDITIONS.
EXPECT MVFR CIGS REMAINING AT THE HIGHEST ELEVATION AIRFIELDS
BFD/JST AND UNV...SHOULD IMPROVE TO VFR BY MIDNIGHT...JOINING ALL
OTHER SITES. SKIES SHOULD THEN BECOME MAINLY CLEAR AT ALL SITES
OVERNIGHT WITH DECREASING WINDS.
OUTLOOK...
THU...VFR. NO SIG WX.
FRI...POSSIBLE MVFR NW WITH SNOW SHOWERS. VFR ELSEWHERE.
SAT AND SUN...VFR...MVFR CIGS POSSIBLE LATE SUN OVER THE WEST.
MON...MVFR/IFR WITH SCATTERED RAIN SHOWERS.
&&
.HYDROLOGY...
A FLASH FLOOD WATCH IS IN EFFECT FOR THE AREA DIRECTLY DOWNSTREAM
FROM THE SPEEDWELL DAM IN LANCASTER COUNTY. THE SPILLWAY WAS
DAMAGED DURING HEAVY RAINS EARLIER THIS FALL WHICH HAVE CAUSED
WATER BEHIND THE DAM TO BUILD UP TO DANGEROUS LEVELS. LOCAL
EMERGENCY MANAGERS WILL CONTINUE TO MONITOR THE SITUATION.
LATEST INFORMATION FROM THE COUNTY HAS NOTED WATER LEVELS
SLOWLY COMING DOWN.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR PAZ066.
&&
$$
SYNOPSIS...FITZGERALD/LA CORTE
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD/LA CORTE
LONG TERM...MARTIN
AVIATION...LA CORTE/GARTNER
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS BROWNSVILLE TX
ISSUED BY NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1116 AM CST TUE NOV 29 2011
.AVIATION...
VFR CONDITIONS WILL CONTINUE THE NEXT 24 HOURS. WEAK FRONT IS
PUSHING THROUGH SOUTH TEXAS WITH WINDS SHIFTING TO THE NORTH LESS
THAN 10 MPH. HRL AND BRO WILL SEE A BRIEF NORTH WIND QUICKLY
VEERING TO THE NORTHEAST BY LATE AFTERNOON. A WEAK GRADIENT WILL
REMAIN TOMORROW WITH LIGHT N AND NE WINDS.
&&
.PREV DISCUSSION... /ISSUED 539 AM CST TUE NOV 29 2011/
DISCUSSION...SEE THE AVIATION SEGMENT BELOW FOR A DISCUSSION OF
THE 12Z TAF PACKAGE. ALSO...SEE THE MARINE SEGMENT BELOW FOR A
MINOR ADJUSTMENT TO THE FIRST PERIOD OF THE COASTAL WATERS
FORECAST.
AVIATION...NO CHANGES WERE NEEDED TO THE EXISTING TAFS. VFR
CONDITIONS WILL CONTINUE TO PREVAIL THROUGH THE NEXT 24 HOURS.
THE PASSAGE OF SURFACE HIGH PRESSURE LOCATED SOUTH OF THE RIO
GRANDE VALLEY TO THE EAST...AS WELL AS THE PASSAGE OF A WEAK COLD
FRONT THROUGH OUR REGION LATER TODAY AND TONIGHT...WILL PRODUCE
MAINLY LIGHT AND VARIABLE WINDS THROUGH THE PERIOD.
MARINE...BUOY 42020 REPORTED SOUTHWEST WINDS AROUND 19 KNOTS WITH
GUSTS TO AROUND 23 KNOTS WITH SEAS SLIGHTLY OVER 4.5 FEET WITH A
PERIOD OF 5 SECONDS AT 05 CST/11 UTC. STRONGER WINDS AND HIGHER
SEAS ARE OCCURRING ALONG THE LOWER TEXAS COAST...A TREND TOTALLY
MISSED BY THE GFS MODEL AND CONFIRMED BY THE RUC. THUS...HAVE
RAISED SMALL CRAFT EXERCISE CAUTION AND INDICATED WINDS OF 15 TO
20 KNOTS FOR THE GULF OF MEXICO WATERS EAST OF PADRE ISLAND FROM
0 TO 60 NAUTICAL MILES OFFSHORE UNTIL NOON TODAY BASED ON THE BUOY
OB AND RUC DATA. RUC SUGGESTS THAT MARINE CONDITIONS WILL IMPROVE
BY THE MID-MORNING TODAY...AT WHICH TIME THE INCOMING SHIFT COULD
LIKELY DISCONTINUE THE SCEC. NO OTHER MARINE FORECAST CHANGES
MADE.
PREV DISCUSSION... /ISSUED 422 AM CST TUE NOV 29 2011/
SHORT TERM /TODAY THROUGH WEDNESDAY/...PLEASANT WEATHER CONDITIONS
WILL DOMINATE THE FIRST 36 HOURS OF THE FORECAST. DRY WEATHER WILL
PREVAIL TODAY AS A MID-LEVEL NORTHWEST-TO-SOUTHEAST FLOW DOMINATES
OVERHEAD...WHILE WARMER TEMPERATURES DEVELOP COURTESY OF A FLOW FROM
THE SOUTH AND SOUTHWEST AT THE SURFACE. ALTHOUGH A WEAK COLD FRONT
WILL PUSH THROUGH DEEP SOUTH TEXAS AND THE RIO GRANDE VALLEY LATER
TODAY AND TONIGHT...COURTESY OF SURFACE HIGH PRESSURE BUILDING SOUTH
AND EAST THROUGH THE LONE STAR STATE...NO RAINFALL IS EXPECTED DUE
TO DRY ATMOSPHERIC CONDITIONS CAUSED BY PRECIPITABLE WATER AMOUNTS
UNABLE TO RECOVER FROM THE RECENT STRONG COLD FRONT. COOL AND DRY
WEATHER IS EXPECTED TONIGHT...WITH DRY WEATHER CONTINUING TOMORROW
ALONG WITH NEAR NORMAL TEMPERATURES...COURTESY OF THE COLD FRONTAL
PASSAGE LATER TODAY AND TONIGHT.
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...THE LONGER RANGE
MODEL GUIDANCE CONTINUES TO ADVERTISE A STRONG MID LEVEL SHORT
WAVE DIVING SOUTH ACROSS THE WEST COAST WED AND THURS. THIS SHORT
WAVE CUTS OFF AND SLOWS DOWN CONSIDERABLY OVER THE DESERT SW LATE
THURS AND FRI. THIS FEATURE THEN OPENS UP AS A MORE PROGRESSIVE
SHORT WAVE FRI NIGHT INTO SAT MOVING INTO THE CENTRAL MISS RIVER
VALLEY SUN. FAIRLY DEEP MOISTURE VALUES POOL AHEAD OF THIS FEATURE
OVER THE SW STATES AND THE NORTHERN HALF OF TX. MEANWHILE DEEP
SOUTH TX WILL REMAIN ON THE SOUTHERN FRINGES OF THIS DEEPER
MOISTURE FIELD AND THE STRONGER MID LEVEL DYNAMICS ASSOCIATED WITH
THE CLOSED LOW/TROUGH. WILL MAINTAIN THE MENTION OF 20 TO 30 %
POPS WITH THE APPROACH AND PASSAGE OF THE COLD FRONT ASSOCIATED
WITH THIS MID LEVEL FEATURE PROVIDING THE BEST SURFACE
CONVERGENCE.
THE GFS AND THE ECMWF CONTINUE TO HAVE SOME TIMING DIFFERENCES
WITH THE HANDLING OF THIS FEATURE. THE GFS HAS A LITTLE FASTER
MOVEMENT OF MID LEVEL TROUGH/CLOSED LOW VERSUS THE ECWMF. THESE
TIMING DIFFERENCES EXTEND ON DOWN TO THE SURFACE WITH THE COLD
FRONT ASSOCIATED WITH THIS SYSTEM MOVING THROUGH FASTER IN THE GFS
SOLUTION VERSUS THE SLOWER ECMWF. THE RUN TO RUN CONSISTENCY WITH
THE GFS MEX MOS IS ABOVE AVERAGE AND WILL GO WITH THE GFS SOLUTION
WHICH IS A LITTLE MORE REALISTIC VERSUS THE ECMWF OUTPUT.
MARINE...TODAY THROUGH WEDNESDAY...A WEAK COLD FRONT WILL PASS
THROUGH THE LOWER TEXAS COAST LATER TODAY AND TONIGHT...BUT NO MAJOR
CHANGES IN WINDS AND SEAS ARE EXPECTED IN THE WAKE OF THE FRONT.
OVERALL...LIGHT TO MODERATE WINDS AND LOW TO MODERATE SEAS WILL
PREVAIL FOR THE ADJACENT COASTAL WATERS OF DEEP SOUTH TEXAS TODAY
THROUGH WEDNESDAY.
WEDNESDAY NIGHT THROUGH SATURDAY...THE FORMATION OF THE CLOSED
MID LEVEL LOW TO THE WEST OF TX WILL RESULT IN A MODERATE TO
STRONG PGF ALONG THE LOWER TX COASTLINE. AS A RESULT EXPECT THE SE
SURFACE FLOW TO INCREASE PUSHING ON UP INTO SCEC/SCA CRIT AFTER
WED.
&&
.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL MMM MMM MMM MMM / MMM MMM MMM MMM
BROWNSVILLE MMM MMM MMM MMM / MMM MMM MMM MMM
HARLINGEN MMM MMM MMM MMM / MMM MMM MMM MMM
MCALLEN MMM MMM MMM MMM / MMM MMM MMM MMM
RIO GRANDE CITY MMM MMM MMM MMM / MMM MMM MMM MMM
SOUTH PADRE ISLAND MMM MMM MMM MMM / MMM MMM MMM MMM
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
HTTP://WWW.WEATHER.GOV/BROWNSVILLE
51/51
AREA FORECAST DISCUSSION...UPDATED
NWS BROWNSVILLE TX
539 AM CST TUE NOV 29 2011
.DISCUSSION...SEE THE AVIATION SEGMENT BELOW FOR A DISCUSSION OF
THE 12Z TAF PACKAGE. ALSO...SEE THE MARINE SEGMENT BELOW FOR A
MINOR ADJUSTMENT TO THE FIRST PERIOD OF THE COASTAL WATERS
FORECAST.
&&
.AVIATION...NO CHANGES WERE NEEDED TO THE EXISTING TAFS. VFR
CONDITIONS WILL CONTINUE TO PREVAIL THROUGH THE NEXT 24 HOURS.
THE PASSAGE OF SURFACE HIGH PRESSURE LOCATED SOUTH OF THE RIO
GRANDE VALLEY TO THE EAST...AS WELL AS THE PASSAGE OF A WEAK COLD
FRONT THROUGH OUR REGION LATER TODAY AND TONIGHT...WILL PRODUCE
MAINLY LIGHT AND VARIABLE WINDS THROUGH THE PERIOD.
&&
.MARINE...BUOY 42020 REPORTED SOUTHWEST WINDS AROUND 19 KNOTS WITH
GUSTS TO AROUND 23 KNOTS WITH SEAS SLIGHTLY OVER 4.5 FEET WITH A
PERIOD OF 5 SECONDS AT 05 CST/11 UTC. STRONGER WINDS AND HIGHER
SEAS ARE OCCURRING ALONG THE LOWER TEXAS COAST...A TREND TOTALLY
MISSED BY THE GFS MODEL AND CONFIRMED BY THE RUC. THUS...HAVE
RAISED SMALL CRAFT EXERCISE CAUTION AND INDICATED WINDS OF 15 TO
20 KNOTS FOR THE GULF OF MEXICO WATERS EAST OF PADRE ISLAND FROM
0 TO 60 NAUTICAL MILES OFFSHORE UNTIL NOON TODAY BASED ON THE BUOY
OB AND RUC DATA. RUC SUGGESTS THAT MARINE CONDITIONS WILL IMPROVE
BY THE MID-MORNING TODAY...AT WHICH TIME THE INCOMING SHIFT COULD
LIKELY DISCONTINUE THE SCEC. NO OTHER MARINE FORECAST CHANGES
MADE.
&&
.PREV DISCUSSION... /ISSUED 422 AM CST TUE NOV 29 2011/
SHORT TERM /TODAY THROUGH WEDNESDAY/...PLEASANT WEATHER CONDITIONS
WILL DOMINATE THE FIRST 36 HOURS OF THE FORECAST. DRY WEATHER WILL
PREVAIL TODAY AS A MID-LEVEL NORTHWEST-TO-SOUTHEAST FLOW DOMINATES
OVERHEAD...WHILE WARMER TEMPERATURES DEVELOP COURTESY OF A FLOW FROM
THE SOUTH AND SOUTHWEST AT THE SURFACE. ALTHOUGH A WEAK COLD FRONT
WILL PUSH THROUGH DEEP SOUTH TEXAS AND THE RIO GRANDE VALLEY LATER
TODAY AND TONIGHT...COURTESY OF SURFACE HIGH PRESSURE BUILDING SOUTH
AND EAST THROUGH THE LONE STAR STATE...NO RAINFALL IS EXPECTED DUE
TO DRY ATMOSPHERIC CONDITIONS CAUSED BY PRECIPITABLE WATER AMOUNTS
UNABLE TO RECOVER FROM THE RECENT STRONG COLD FRONT. COOL AND DRY
WEATHER IS EXPECTED TONIGHT...WITH DRY WEATHER CONTINUING TOMORROW
ALONG WITH NEAR NORMAL TEMPERATURES...COURTESY OF THE COLD FRONTAL
PASSAGE LATER TODAY AND TONIGHT.
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...THE LONGER RANGE
MODEL GUIDANCE CONTINUES TO ADVERTISE A STRONG MID LEVEL SHORT
WAVE DIVING SOUTH ACROSS THE WEST COAST WED AND THURS. THIS SHORT
WAVE CUTS OFF AND SLOWS DOWN CONSIDERABLY OVER THE DESERT SW LATE
THURS AND FRI. THIS FEATURE THEN OPENS UP AS A MORE PROGRESSIVE
SHORT WAVE FRI NIGHT INTO SAT MOVING INTO THE CENTRAL MISS RIVER
VALLEY SUN. FAIRLY DEEP MOISTURE VALUES POOL AHEAD OF THIS FEATURE
OVER THE SW STATES AND THE NORTHERN HALF OF TX. MEANWHILE DEEP
SOUTH TX WILL REMAIN ON THE SOUTHERN FRINGES OF THIS DEEPER
MOISTURE FIELD AND THE STRONGER MID LEVEL DYNAMICS ASSOCIATED WITH
THE CLOSED LOW/TROUGH. WILL MAINTAIN THE MENTION OF 20 TO 30 %
POPS WITH THE APPROACH AND PASSAGE OF THE COLD FRONT ASSOCIATED
WITH THIS MID LEVEL FEATURE PROVIDING THE BEST SURFACE
CONVERGENCE.
THE GFS AND THE ECMWF CONTINUE TO HAVE SOME TIMING DIFFERENCES
WITH THE HANDLING OF THIS FEATURE. THE GFS HAS A LITTLE FASTER
MOVEMENT OF MID LEVEL TROUGH/CLOSED LOW VERSUS THE ECWMF. THESE
TIMING DIFFERENCES EXTEND ON DOWN TO THE SURFACE WITH THE COLD
FRONT ASSOCIATED WITH THIS SYSTEM MOVING THROUGH FASTER IN THE GFS
SOLUTION VERSUS THE SLOWER ECMWF. THE RUN TO RUN CONSISTENCY WITH
THE GFS MEX MOS IS ABOVE AVERAGE AND WILL GO WITH THE GFS SOLUTION
WHICH IS A LITTLE MORE REALISTIC VERSUS THE ECMWF OUTPUT.
MARINE...TODAY THROUGH WEDNESDAY...A WEAK COLD FRONT WILL PASS
THROUGH THE LOWER TEXAS COAST LATER TODAY AND TONIGHT...BUT NO MAJOR
CHANGES IN WINDS AND SEAS ARE EXPECTED IN THE WAKE OF THE FRONT.
OVERALL...LIGHT TO MODERATE WINDS AND LOW TO MODERATE SEAS WILL
PREVAIL FOR THE ADJACENT COASTAL WATERS OF DEEP SOUTH TEXAS TODAY
THROUGH WEDNESDAY.
WEDNESDAY NIGHT THROUGH SATURDAY...THE FORMATION OF THE CLOSED
MID LEVEL LOW TO THE WEST OF TX WILL RESULT IN A MODERATE TO
STRONG PGF ALONG THE LOWER TX COASTLINE. AS A RESULT EXPECT THE SE
SURFACE FLOW TO INCREASE PUSHING ON UP INTO SCEC/SCA CRIT AFTER
WED.
&&
.BRO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
HTTP://WWW.WEATHER.GOV/BROWNSVILLE
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
816 PM MST WED NOV 30 2011
.UPDATE...
WINTER STORM STILL APPEARS TO BE ON TRACK ACROSS MUCH OF SOUTHEAST
WYOMING AND THE WESTERN NEBRASKA PANHANDLE IN THE WAKE OF A STRONG
COLD FRONT MOVING RAPIDLY SOUTHEASTWARD ACROSS THE REGION. THIS
FRONT HAS ALREADY CLEARED OUR FORECAST AREA...WITH 3-HOUR PRESSURE
RISES RANGING FROM 3 TO 5 MILLIBARS OVERSPREADING A LARGE PORTION
OF CENTRAL AND EASTERN WYOMING. NORTH TO NORTHEAST WINDS HAVE
INCREASED TO BETWEEN 20 AND 30 MPH ACROSS MOST AREAS...WITH GUSTS
AS HIGH AS 35 MPH. THESE WINDS SHOULD PERSIST...AND PERHAPS
INCREASE OVERNIGHT AS H7-H75 WINDS INCREASE TO BETWEEN 35 AND 40
KTS...ESPECIALLY OVER OUR MOUNTAIN ZONES.
RECENT TRENDS IN RADAR AND INFRARED SATELLITE IMAGERY/COOLING
CLOUD TOPS INDICATE SNOW IS BEGINNING TO INCREASE IN COVERAGE AND
INTENSITY ACROSS MUCH OF SOUTHEAST WYOMING. THE INHERITED WINTER
STORM WARNING LOOKS GOOD WITH THE POTENTIAL FOR SIGNIFICANT
BLOWING AND DRIFTING SNOW DESPITE SNOW AMOUNTS LIKELY STRUGGLING
TO REACH WARNING CRITERIA. HIGH SNOW RATIOS IN EXCESS OF 15 TO 1
ARE ALSO LIKELY AS H7 TEMPERATURES PLUNGE TO BETWEEN -10C AND
-15C...SO FRESH SNOW SHOULD BE EASY TO BLOW AROUND. THE LATEST
CONCERN IS THE NORTHERN LARAMIE RANGE...WITH NORTH-FACING SLOPES
BEING ESPECIALLY PRONE TO UPSLOPE ENHANCEMENT LATER TONIGHT. THIS
AREA IS BEING HIT HARD BY THE NAM AND ECMWF...WHICH SEEMS QUITE
REALISTIC GIVEN THE LOW-LEVEL FLOW REGIME. WITH 5 TO 10 INCHES OF
SNOW AND WIND GUSTS IN EXCESS OF 40 MPH...WE HAVE OPTED TO ADD OUR
FAR NORTHWEST MOUNTAIN ZONES TO THE CURRENT WINTER STORM WARNING. THE
SNOW AND BLOWING SNOW ADVISORY HAS ALSO BEEN EXPANDED TO INCLUDE
THE REMAINDER OF THE WESTERN NEBRASKA PANHANDLE...AND CONVERSE AND
NIOBRARA COUNTIES IN EAST CENTRAL WYOMING. WIND WILL BE THE
BIGGEST CONCERN ACROSS THESE AREAS AS VERY STRONG PRESSURE RISES
OVERSPREAD THE REGION BY DAYBREAK THURSDAY. MODEST SNOW
ACCUMULATIONS AND WINDS IN EXCESS OF 30 MPH SHOULD BE MORE THAN
SUFFICIENT FOR HAZARDOUS TRAVEL.
&&
AVIATION...00Z TAFS
COLD FRONT ABOUT TO MOVE INTO SOUTHEASTERN WYOMING LATE THIS
AFTERNOON. ALREADY SEEING SNOW REPORTS AT KGCC AND KBYG OVER
NORTHERN WYOMING. EXPECTING THIS SNOW TO FIRST BEGIN AT RAWLINS IN
NEXT 2-3 HOURS...SPREADING SOUTHEASTWARD AS THE FRONT TRACKS
SOUTH. TRIED TO FOLLOW HRRR GUIDANCE THE CLOSEST...BUT DO BELIEVE
IT MAY BE TOO FAST. SO DELAYED ONSET OF IFR CONDITIONS BY 1-2
HOURS. ONCE SNOW STARTS...BELIEVE CONDITIONS AT OUR AIRPORTS WILL
DETERIORATE QUICKLY...DROPPING TO IFR WITH SNOW ONSET...LIFR ONCE
THE WINDS START PICKING UP. CONTINUED THE TREND OF STRONG WINDS
CAUSING BLOWING AND DRIFTING SNOWS THROUGH THURSDAY MORNING.
CLAYCOMB
&&
PREV DISCUSSION... /ISSUED 202 PM MST WED NOV 30 2011/
SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT.
TONIGHT...THE FINAL DAY OF NOVEMBER WILL GO OUT LIKE A LAMB WITH
HIGH TEMPERATURES IN THE 40S AND 50S...WITH THE FIRST DAY OF
DECEMBER COMING IN LIKE A LION AS A STRONG COLD FRONT QUICKLY ROARS
THROUGH OUR COUNTIES BY EARLY EVENING. 3 HOURLY PRESSURE RISES OF 2
TO 7 MB OCCURRING ACROSS NORTHERN MONTANA WILL KEEP THE FRONT
BARRELING SOUTH.
CURRENT WINTER STORM WARNING AND WINTER WEATHER ADVISORY AREAS AND
TIMING LOOK GOOD BASED ON EXPECTED SNOWFALL AMOUNTS...AND ESPECIALLY
WITH THE COMBINATION OF BLOWING SNOW...REDUCED VISIBILITIES AND COLD
TEMPERATURES.
WIDESPREAD SNOW WILL DEVELOP THIS EVENING ACROSS SOUTHEAST WYOMING
AND SPREAD ACROSS WESTERN NEBRASKA LATE TONIGHT...LAGGING THE COLD
FRONT BY A FEW HOURS. STRONG SURFACE THROUGH 700 MB GRADIENTS WILL
PRODUCE BRISK NORTH WINDS DUE TO STRONG THICKNESS PACKING.
COMBINATION OF FALLING SNOW AND WINDS WILL PRODUCE AREAS OF BLOWING
SNOW AND VISIBILITIES NEAR ZERO.
THURSDAY...WIDESPREAD SNOW AND BLOWING SNOW CONTINUE IN THE MORNING
SOUTH OF A RAWLINS TO SCOTTSBLUFF LINE WITH SNOW TAPERING OFF TO THE
NORTH. IN THE AFTERNOON...SNOW WILL END IN THE NORTH WITH SNOW
DECREASING IN AREAL COVERAGE AND INTENSITY ACROSS OUR SOUTHERN
COUNTIES. MUCH COLDER WITH HIGHS IN THE TEENS AND 20S.
TOTAL MOUNTAIN SNOWFALL AMOUNTS WILL RANGE FROM 10 TO 14 INCHES...
WITH 4 TO 7 INCHES WEST OF A DOUGLAS TO CHEYENNE LINE AND 1 TO 4
INCHES ELSEWHERE.
THURSDAY NIGHT...VERY COLD WITH CLOUDS DECREASING AND FRESH SNOW
COVER. LOWS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO.
FRIDAY...SLIGHT WARMING TREND IN ADVANCE OF THE NEXT REINFORCING
SHOT OF COLD AIR...THOUGH LIMITED BY RESIDUAL SNOW COVER.
FRIDAY NIGHT...NEXT SHORTWAVE TROUGH ALOFT AND COLD FRONT WILL BRING
SNOW AGAIN SOUTH OF A DOUGLAS TO SIDNEY LINE...THOUGH SNOWFALL
AMOUNTS WILL BE MORE LIMITED WITH LESS MOISTURE AVAILABILITY AND
LESS LIFT.
LONG TERM...SATURDAY THROUGH WEDNESDAY...THE 12Z MEDIUM RANGE MODELS
ALL DEPICT A HIGHLY AMPLIFIED UPPER LEVEL PATTERN ACROSS THE LOWER
48. A POSITIVELY-TILTED MEAN TROUGH WILL EXTEND FROM HUDSON BAY IN
CANADA TO THE FOUR CORNERS REGION...WITH A MEAN UPPER RIDGE OVER
THE NORTHEASTERN PACIFIC. A SERIES OF SHORT WAVES WILL TOP THE RIDGE
AND DROP SOUTH/SOUTHEAST THROUGH CENTRAL AND SOUTHERN CANADA INTO
THE NORTH CENTRAL STATES DURING THE PERIOD...REINFORCING THE MEAN
TROUGH. THIS PATTERN WILL MAINTAIN BELOW NORMAL TEMPERATURES WITH
A FEW CANADIAN COLD FRONTAL PASSAGES. THE UPPER LEVEL SYSTEM
RESPONSIBLE FOR THE LIGHT SNOW ON SATURDAY WILL MOVE EAST INTO
THE PLAINS SATURDAY NIGHT. IT WILL BE COLDER ON SATURDAY IN THE
WAKE OF A COLD FRONT WITH BRISK NORTHERLY WINDS. SATURDAY NIGHT
WILL BE COLD BUT DRY. THE NEXT COLD FRONT AND UPPER LEVEL
DISTURBANCE DROPS QUICKLY SOUTH THROUGH THE HIGH PLAINS SUNDAY AND
SUNDAY NIGHT WITH CHANCES FOR LIGHT SNOW MAINLY ALONG AND WEST OF
THE LARAMIE RANGE. POST-FRONTAL AIRMASS IS MODIFIED SO TEMPERATURES
WILL NOT BE AS CHILLY AS THE PREVIOUS SYSTEM. THE UPPER FLOW
BACKS FROM NORTHERLY TO WESTERLY ON TUESDAY IN ADVANCE OF THE
NEXT POTENT SHORT WAVE ENTERING THE NORTHWEST TIER OF THE NATION.
DOWNSLOPING EAST OF THE LARAMIE RANGE WILL RESULT IN WARMER...MORE
SEASONAL TEMPERATURES. THE NEXT COLD FRONT MOVES SOUTHEAST ACROSS
CENTRAL AND EASTERN WYOMING WEDNESDAY WITH CHANCES FOR RAIN/SNOW
ALONG WITH COOLER TEMPERATURES FOR NORTHERN AND WESTERN PORTIONS
OF THE CWA.
FIRE WEATHER...NO FIRE WEATHER CONCERNS.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 3 PM THURSDAY FOR WYZ103-WYZ104-
WYZ105-WYZ109-WYZ110-WYZ111-WYZ112-WYZ113-WYZ114.
WINTER STORM WARNING FROM 11 PM WEDNESDAY TO 3 PM THURSDAY FOR
WYZ115-WYZ116-WYZ117-WYZ118-WYZ119.
WINTER WEATHER ADVISORY FROM 11 PM WEDNESDAY TO 3 PM THURSDAY
FOR WYZ101-WYZ102-WYZ106-WYZ107-WYZ108.
NE...WINTER WEATHER ADVISORY FROM 11 PM WEDNESDAY TO 3 PM THURSDAY
FOR NEZ002-NEZ003-NEZ019-NEZ020-NEZ021-NEZ054-NEZ055-NEZ095-
NEZ096.
&&
$$
UPDATE...HAMMER/CLAYCOMB
SHORT TERM...RUBIN LONG
TERM/AVIATION...JAMSKI
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
418 PM MST WED NOV 30 2011
.AVIATION...00Z TAFS
COLD FRONT ABOUT TO MOVE INTO SOUTHEASTERN WYOMING LATE THIS
AFTERNOON. ALREADY SEEING SNOW REPORTS AT KGCC AND KBYG OVER
NORTHERN WYOMING. EXPECTING THIS SNOW TO FIRST BEGIN AT RAWLINS IN
NEXT 2-3 HOURS...SPREADING SOUTHEASTWARD AS THE FRONT TRACKS
SOUTH. TRIED TO FOLLOW HRRR GUIDANCE THE CLOSEST...BUT DO BELIEVE
IT MAY BE TOO FAST. SO DELAYED ONSET OF IFR CONDITIONS BY 1-2
HOURS. ONCE SNOW STARTS...BELIEVE CONDITIONS AT OUR AIRPORTS WILL
DETERIORATE QUICKLY...DROPPING TO IFR WITH SNOW ONSET...LIFR ONCE
THE WINDS START PICKING UP. CONTINUED THE TREND OF STRONG WINDS
CAUSING BLOWING AND DRIFTING SNOWS THROUGH THURSDAY MORNING.
CLAYCOMB
CLAYCOMB
&&
.PREV DISCUSSION... /ISSUED 202 PM MST WED NOV 30 2011/
SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT.
TONIGHT...THE FINAL DAY OF NOVEMBER WILL GO OUT LIKE A LAMB WITH
HIGH TEMPERATURES IN THE 40S AND 50S...WITH THE FIRST DAY OF
DECEMBER COMING IN LIKE A LION AS A STRONG COLD FRONT QUICKLY ROARS
THROUGH OUR COUNTIES BY EARLY EVENING. 3 HOURLY PRESSURE RISES OF 2
TO 7 MB OCCURRING ACROSS NORTHERN MONTANA WILL KEEP THE FRONT
BARRELING SOUTH.
CURRENT WINTER STORM WARNING AND WINTER WEATHER ADVISORY AREAS AND
TIMING LOOK GOOD BASED ON EXPECTED SNOWFALL AMOUNTS...AND ESPECIALLY
WITH THE COMBINATION OF BLOWING SNOW...REDUCED VISIBILITIES AND COLD
TEMPERATURES.
WIDESPREAD SNOW WILL DEVELOP THIS EVENING ACROSS SOUTHEAST WYOMING
AND SPREAD ACROSS WESTERN NEBRASKA LATE TONIGHT...LAGGING THE COLD
FRONT BY A FEW HOURS. STRONG SURFACE THROUGH 700 MB GRADIENTS WILL
PRODUCE BRISK NORTH WINDS DUE TO STRONG THICKNESS PACKING.
COMBINATION OF FALLING SNOW AND WINDS WILL PRODUCE AREAS OF BLOWING
SNOW AND VISIBILITIES NEAR ZERO.
THURSDAY...WIDESPREAD SNOW AND BLOWING SNOW CONTINUE IN THE MORNING
SOUTH OF A RAWLINS TO SCOTTSBLUFF LINE WITH SNOW TAPERING OFF TO THE
NORTH. IN THE AFTERNOON...SNOW WILL END IN THE NORTH WITH SNOW
DECREASING IN AREAL COVERAGE AND INTENSITY ACROSS OUR SOUTHERN
COUNTIES. MUCH COLDER WITH HIGHS IN THE TEENS AND 20S.
TOTAL MOUNTAIN SNOWFALL AMOUNTS WILL RANGE FROM 10 TO 14 INCHES...
WITH 4 TO 7 INCHES WEST OF A DOUGLAS TO CHEYENNE LINE AND 1 TO 4
INCHES ELSEWHERE.
THURSDAY NIGHT...VERY COLD WITH CLOUDS DECREASING AND FRESH SNOW
COVER. LOWS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO.
FRIDAY...SLIGHT WARMING TREND IN ADVANCE OF THE NEXT REINFORCING
SHOT OF COLD AIR...THOUGH LIMITED BY RESIDUAL SNOW COVER.
FRIDAY NIGHT...NEXT SHORTWAVE TROUGH ALOFT AND COLD FRONT WILL BRING
SNOW AGAIN SOUTH OF A DOUGLAS TO SIDNEY LINE...THOUGH SNOWFALL
AMOUNTS WILL BE MORE LIMITED WITH LESS MOISTURE AVAILABILITY AND
LESS LIFT.
LONG TERM...SATURDAY THROUGH WEDNESDAY...THE 12Z MEDIUM RANGE MODELS
ALL DEPICT A HIGHLY AMPLIFIED UPPER LEVEL PATTERN ACROSS THE LOWER
48. A POSITIVELY-TILTED MEAN TROUGH WILL EXTEND FROM HUDSON BAY IN
CANADA TO THE FOUR CORNERS REGION...WITH A MEAN UPPER RIDGE OVER
THE NORTHEASTERN PACIFIC. A SERIES OF SHORT WAVES WILL TOP THE RIDGE
AND DROP SOUTH/SOUTHEAST THROUGH CENTRAL AND SOUTHERN CANADA INTO
THE NORTH CENTRAL STATES DURING THE PERIOD...REINFORCING THE MEAN
TROUGH. THIS PATTERN WILL MAINTAIN BELOW NORMAL TEMPERATURES WITH
A FEW CANADIAN COLD FRONTAL PASSAGES. THE UPPER LEVEL SYSTEM
RESPONSIBLE FOR THE LIGHT SNOW ON SATURDAY WILL MOVE EAST INTO
THE PLAINS SATURDAY NIGHT. IT WILL BE COLDER ON SATURDAY IN THE
WAKE OF A COLD FRONT WITH BRISK NORTHERLY WINDS. SATURDAY NIGHT
WILL BE COLD BUT DRY. THE NEXT COLD FRONT AND UPPER LEVEL
DISTURBANCE DROPS QUICKLY SOUTH THROUGH THE HIGH PLAINS SUNDAY AND
SUNDAY NIGHT WITH CHANCES FOR LIGHT SNOW MAINLY ALONG AND WEST OF
THE LARAMIE RANGE. POST-FRONTAL AIRMASS IS MODIFIED SO TEMPERATURES
WILL NOT BE AS CHILLY AS THE PREVIOUS SYSTEM. THE UPPER FLOW
BACKS FROM NORTHERLY TO WESTERLY ON TUESDAY IN ADVANCE OF THE
NEXT POTENT SHORT WAVE ENTERING THE NORTHWEST TIER OF THE NATION.
DOWNSLOPING EAST OF THE LARAMIE RANGE WILL RESULT IN WARMER...MORE
SEASONAL TEMPERATURES. THE NEXT COLD FRONT MOVES SOUTHEAST ACROSS
CENTRAL AND EASTERN WYOMING WEDNESDAY WITH CHANCES FOR RAIN/SNOW
ALONG WITH COOLER TEMPERATURES FOR NORTHERN AND WESTERN PORTIONS
OF THE CWA.
&&
FIRE WEATHER...NO FIRE WEATHER CONCERNS.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 3 PM THURSDAY FOR WYZ104-WYZ109-
WYZ110-WYZ111-WYZ112-WYZ113-WYZ114.
WINTER STORM WARNING FROM 11 PM WEDNESDAY TO 3 PM THURSDAY FOR
WYZ115-WYZ116-WYZ117-WYZ118-WYZ119.
WINTER WEATHER ADVISORY FROM 11 PM WEDNESDAY TO 3 PM THURSDAY
FOR WYZ106-WYZ107-WYZ108.
NE...WINTER WEATHER ADVISORY FROM 11 PM WEDNESDAY TO 3 PM THURSDAY
FOR NEZ020-NEZ054.
&&
$$
SHORT TERM...RUBIN
LONG TERM/AVIATION...JAMSKI
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1015 PM MST MON NOV 28 2011
.AVIATION...06Z TAFS
LATEST SATELLITE IMAGERY CONTINUES TO SHOW LOW CLOUDS NOT
DEVELOPING EAST OF THE LARAMIE RANGE WHICH IS SUPPORTED BY LATEST
HRRR GUIDANCE. CONFIDENCE HIGH THAT LOW CEILINGS WILL PROBABLY NOT
DEVELOP OVERNIGHT FOR MOST LOCATIONS. THE EXCEPTION BEING RAWLINS
WHERE HRRR SHOWING SOME PATCHY IFR CONDITIONS DEVELOPING AROUND
THE 08Z-09Z TIME FRAME. GOING TO BE A REAL HIT/MISS TYPE SCENARIO
OUT THAT WAY...SO OPTED FOR AN MVFR FORECAST FROM 08Z THROUGH
SUNRISE.
CONDITIONS REALLY CHANGE WEDNESDAY NIGHT INTO THURSDAY AS A STRONG
COLD FRONT PUSHES INTO SOUTHEAST WYOMING. SNOW EXPECTED ALONG WITH
STRONG NORTH WINDS LATE WEDNESDAY AFTERNOON THROUGH THURSDAY
MORNING.
CLAYCOMB
&&
PREV DISCUSSION... /ISSUED 256 PM MST MON NOV 28 2011/
SHORT TERM...TONIGHT THROUGH WEDNESDAY...
CURRENTLY COLD FRONT ON THE DOORSTEP OF KCYS. WINDS HAVE SHIFTED
TO THE NORTHWEST AND ARE GUSTING INTO THE MID 30S BUT TEMPERATURE
REMAINING STEADY SO FAR. LOOKING AT PRESSURE CHANGE AND
OBSERVATIONS LOOKS LIKE THE FRONT HAS ALSO MOVED THROUGH THE
SOUTHERN PANHANDLE. RADAR REMAINED PPINE WITH THE FRONT AND
SATELLITE SHOWED MAINLY MID CLOUDS.
THIS MORNINGS UPPER PACKAGE PLENTY OF WARM AIR AHEAD OF THE SYSTEM
THAT IS MOVING THROUGH THE AREA. FLOW WAS GENERALLY FROM THE WEST
WITH LITTLE MOISTURE.
FORECAST PROBLEM FOR THIS PACKAGE WILL BE WINDS AND TEMPERATURES.
LOOKS LIKE HIGH PRESSURE WILL SETTLE ACROSS THE CWA TONIGHT BEHIND
THE FRONT AND GUSTY WINDS WILL PERSIST UNTIL AFTER SUNSET. TUESDAY
SHOULD BE DRY AND COOLER THAN TODAY BUT ANOTHER SYSTEM MOVING
MOVING INTO THE PACIFIC NORTHWEST WILL QUICKLY BRING THE WINDS
AROUND AND TEMPER SIGNIFICANT COOLING. THE NEXT SYSTEM WILL
CONTINUE TO APPROACH AND ON WEDNESDAY WILL SEE CLOUDS INCREASING.
BY WEDNESDAY AFTERNOON COULD POSSIBLY START TO SEE SOME
PRECIPITATION IN THE HIGH COUNTRY AND IN THE NORTHERN CWA BUT THE
SNOW SHOULD BEGIN IN EARNEST AFTER 01/00Z.
FOR THE SHORT TERM TEMPERATURES LOOK TO BE AROUND NORMAL.
LONG TERM...WEDNESDAY NIGHT-MONDAY
THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE SNOW POTENTIAL
ON WEDNESDAY NIGHT INTO THURSDAY AND HOW COLD TEMPERATURES WILL BE
THROUGH THE WEEK.
LATEST WATER VAPOR LOOP WAS SHOWING TWO DISTINCT UPPER LEVEL
VORTICITY LOBES MOVING THROUGH THE EASTERN PACIFIC. THE FIRST WAVE
WAS AROUND 42 DEG N AND 155 DEG W...WHILE THE TRAILING WAVE WAS 44
DEG N AND 176 N. THE MODELS SEEM TO BE IN FAIRLY GOOD AGREEMENT
IN SHOWING THE FIRST WAVE DIGGING ACROSS THE SOUTHERN ROCKIES
DURING THE NEXT COUPLE OF DAYS WHICH WILL CAUSE THE FLOW TO SPLIT AS
THE NEXT WAVE SKIRTS ACROSS THE NORTHERN ROCKIES LATER IN THE WEEK.
THE FIRST UPPER LEVEL WAVE SHOULD BEGIN TO IMPACT THE AREA
BEGINNING LATE WEDNESDAY AFTERNOON AND CONTINUING UNTIL THURSDAY
AFTERNOON. THIS WAVE WILL HAVE AID FROM THE RIGHT ENTRANCE REGION OF
THE UPPER LEVEL JET...BUT IT WILL BE RATHER SHORT LIVED. THE MODELS
ARE SHOWING SOME WEAK POTENTIAL INSTABILITY BETWEEN 700-500MB NEAR
CASPER AROUND 06Z. OTHERWISE...THIS SYSTEM SHOULD HAVE DEEP ENOUGH
MOISTURE AND LIFT BEHIND THE FRONT TO PRODUCE SOME LIGHT TO MODERATE
SNOWFALL BEGINNING LATE WEDNESDAY AFTERNOON IN THE NORTHERN HALF OF
THE FORECAST AREA WITH THIS SNOW SPREADING INTO THE SOUTHERN HALF OF
THE FORECAST AREA WEDNESDAY NIGHT. SNOWFALL ACCUMULATIONS SHOULD
GENERALLY BE AROUND 2-4 INCHES WITH HIGHER AMOUNTS IN THE MOUNTAINS
WHERE THE SNOW RATIOS WILL BE A LITTLE GREATER. THE MAIN LIMITATION
FOR MUCH IN THE WAY OF ACCUMULATION WILL BE THE SHORT LIVED NATURE OF
THE HEAVIER SNOWFALL. THIS WILL MOST LIKELY TAKE PLACE WEDNESDAY
EVENING WHEN THE COLD AIR AIR ADVECTION WILL BE THE STRONGEST WITH
SOME WEAK SHORT LIVED MID LEVEL FRONTOGENISIS (700-500MB) POSSIBLE.
THE SNOW SHOULD BEGIN TO TAPER OFF FROM NORTH TO SOUTH ON THURSDAY.
TEMPERATURES WILL TURN SHARPLY COLDER WITH GUSTY NORTH WINDS
AT 30 TO 40 MPH POSSIBLE ON WEDNESDAY EVENING INTO THURSDAY
MORNING. TEMPERATURES WILL ALSO NOT BUDGE MUCH ON THURSDAY WITH
HIGHS GENERALLY IN THE TEENS AND LOW 20S WHICH WILL ONLY BE A COUPLE
OF DEGREES WARMER THAN MORNING LOWS. MEANWHILE...LOWS ON THURSDAY
NIGHT COULD BE QUITE CHILLY (SINGLE DIGITS TO BELOW ZERO IN THE
VALLEYS) DUE TO THE 1040MB SURFACE HIGH SETTLING OVER THE AREA. WE
REALLY BACKED OFF ON HIGHS COMPARED TO THE GUIDANCE NUMBERS FOR
THIS TIME FRAME.
FRIDAY-MONDAY:
THE NEXT CONCERN DURING THIS TIME FRAME...WILL BE THE ARRIVAL OF
THE NEXT WAVE ON SATURDAY INTO SUNDAY. THE MAIN CONCERN WITH THIS
SYSTEM WILL BE HOW MUCH THIS TROF WILL AMPLIFY AS IT APPROACHES
THE CANADIAN ROCKIES. THIS WILL DETERMINE HOW MUCH COLD AIR SPILLS
INTO THE REGION THIS WEEKEND. IF THIS TROF DOES AMPLIFY...WE COULD
SEE ARCTIC AIR SPILLING INTO THE AREA BEGINNING SATURDAY AND
CONTINUING THROUGH MONDAY. SNOW CHANCES LOOK TO BE FAIRLY SMALL AT
THIS TIME WITH VERY LITTLE IF ANY ACCUMULATION. OF COURSE...THIS
WILL BE DEPENDENT ON HOW MUCH MOISTURE WILL BE AVAILABLE.
&&
FIRE WEATHER...
WIND SPEEDS WILL CONTINUE TO DIMINISH TONIGHT. OTHERWISE...THE
ONLY CONCERN WILL BE THE HIGH WIND POTENTIAL ON WEDNESDAY NIGHT
INTO THURSDAY...BUT THE PRECIPITATION CHANCES WILL BE QUITE HIGH
WHICH WILL LIMIT FIRE WEATHER CONCERNS.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM...GRIFFITH
LONG TERM/AVIATION...REC
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
305 AM EST Thu Dec 01 2011
.SYNOPSIS...
07Z water vapor and H4 RUC analysis shows an active upper level
pattern across the CONUS this morning. Sharp troughing covers the
inter-mountain west with a potent shortwave at its base digging
southward over CA/NV. This energy is progged to close off over the
next several hours and stall. Further downstream the flow leaving
the southwestern states ridges northward across the Central
Plains/Middle and lower MS valley. Finally we find troughing about
to exit off the Atlantic seaboard. The base of this trough contains
a fairly sharp/potent shortwave that is just now exiting east of our
forecast area. Large scale subsidence on the backside of this
impulse is working to continue drying our our atmospheric column,
and will help contribute to abundant sunshine for our Thursday. The
KTLH 00Z sounding profile already showed an impressively low PW
values of 0.31" (only about 33% of climo for early December). With
the ongoing subsidence...would anticipate the 12Z profile to be even
lower. In fact both the GFS and NAM prog PW values down as low as
0.2" by sunrise.
At the surface,
1025mb ridge of high pressure is centered from the TN Valley to the
MS/AL border region. The influence of this ridge extends into our
forecast area with a weak gradient now in place. This weak gradient
has allowed winds to go very light/calm early this morning and
boundary layer decoupling appears to have already occurred at many
locations. Good radiational cooling within the decoupled layer has
allowed many stations to reach the freezing mark or lower this
morning. At this time the freeze warning appears on track and do not
anticipate making any significant changes to the forecast through
sunrise.
&&
.SHORT TERM (TODAY THROUGH SATURDAY)...
Today,
Pleasant day on tap after a cold start. Heights will rise over the
region in the wake of the departing shortwave trough. The rising
heights along with the building surface high building will lead to
stacked ridging dominating our weather by the end of the day. The
weak low level gradient and near solar minimum sun angle will not
lead to efficient mixing today. High temperatures will again end up
below normal despite abundant sunshine. Temperatures will struggle
into the lower 60s by mid-afternoon across a majority of the area,
with a few middle 60s down toward Perry, Mayo, and Cross City.
Tonight,
Clear skies, dry low levels, and the surface ridge axis still in
close proximity will allow for another fairly cold night. It does
not appear likely that we will see the areal coverage of freezing or
sub-freezing temperatures that are occurring this morning, nor does
it appear that we will see the durations of freezing temperatures.
Minimum temperature grids will show widespread lower to middle 30s
away from the immediate coast. These temperatures combined with the
light winds and small dewpoint depressions should still lead to
areas of frost development. The forecast will show this frost
potential for all areas expected to reach 35 degrees or lower.
Normally colder spots are forecast to briefly drop below freezing
(30-32F) around sunrise, however the overall coverage at this time
is not anticipated to warrant another freeze watch/warning event.
Friday Through Saturday,
Stacked ridging will remain in control of our weather providing dry,
seasonable, and slowly warming conditions into the first half of the
upcoming weekend. Temperatures Friday will rebound upward several
degrees from Thursday`s highs. Current grids will show mainly middle
to upper 60s, with lower 70s over the SE Big Bend Zones. Very dry
atmosphere will keep our skies sunny.
Strong high pressure will redevelop and build down the eastern
seaboard later Friday and Friday night. ECMWF/GFS both show surface
pressures with this high reaching 1036-1038mb over the mid-Atlantic
region. The effect for our region will be a significant tightening
of the gradient and resulting easterly flow. This easterly flow will
begin to transport low level Atlantic moisture back into the region.
Due to the tighter gradient and increased moisture, do not
anticipate the potential for freezing temps or likely even any frost
Friday night. It will still be cool, but the coldest inland temps
currently in the grids show mid/upper 30s. Temps warmer still will
be experienced along the coast from Wakulla County westward due to
the easterly/ESE flow.
More of the same for Saturday with perhaps a few-sct afternoon cu
field. More efficient mixing due to the tighter gradient will allow
temps to climb toward the lower 70s across much of the area.
&&
.LONG TERM (SUNDAY THROUGH NEXT THURSDAY)...
The Guidance is in decent agreement through Sunday night before
significant differences begin to arise. Through Sunday night, a
ridge will be in place over the Southeastern states, with dry
conditions and temperatures back near climo. A strong surface high
over New England will keep northeast flow in place across the region
Sunday and prevent temperatures from warming more significantly.
This high shifts well east by Monday, allowing for a more
substantial warm-up.
Significant model differences are evident by Monday through
Wednesday with the deep longwave trough over the central states. The
CMC and GFS are more progressive with the system and bring the
surface front through the region late Monday or early Tuesday. The
ECMWF and UKMET cutoff the tail of the trough leading to a much
slower progression, and a frontal passage Tuesday night or early
Wednesday. With significant uncertainty, have decided to take a
compromise of all the guidance, leading to a frontal passage on
Tuesday. A band of showers is expected with the front. However, the
bulk of the dynamics and lift are expected to pull northeast of the
area, with coverage on the decrease as the front crosses the region.
A much cooler airmass will spill into the region in the wake of the
front.
&&
.MARINE...
A ridge of high pressure will slide to the north of the forecast
waters through Friday. Northerly flow will come around to Northeast
and then east through this time. Cautionary level winds may briefly
decrease below headline criteria later this morning and into the
afternoon, but will increase back to cautionary levels tonight. The
gradient will tighten Friday night into Saturday as a new and
stronger area of high pressure builds down the eastern seaboard.
This tighter gradient will lead to a prolonged period of cautionary
to advisory level easterly flow through the upcoming weekend. The
next cold front will then approach from the west during the early
portion of next week.
&&
.AVIATION (through Friday 06z)...With high pressure building into
the region, VFR conditions and light winds are expected to prevail
through the forecast period. May see a brief period of MVFR VSBY at
KDHN this morning, as indicated by some of the numerical guidance.
However, VSBY should stay at or above 5SM.
&&
.FIRE WEATHER...
A dry airmass will remain in place over the region through Friday.
Cool temperatures will prevent RH values from dropping to critical
levels today. Slightly warmer temperatures on Friday will allow for
sub-35 percent RH across the Florida zones. However, ERC values are
expected to remain below 35. Therefore, no Fire Weather Watch is
planned at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 63 33 68 39 72 / 0 0 0 0 0
Panama City 62 40 67 47 68 / 0 0 0 0 0
Dothan 61 34 67 39 70 / 0 0 0 0 0
Albany 62 32 67 36 70 / 0 0 0 0 0
Valdosta 63 33 67 39 72 / 0 0 0 0 0
Cross City 67 36 71 41 75 / 0 0 0 0 0
Apalachicola 61 40 65 46 69 / 0 0 0 0 0
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...Freeze Warning until 8 AM CST this morning for Coffee-Dale-
Geneva-Henry-Houston.
GA...Freeze Warning until 9 AM EST this morning for Baker-Ben Hill-
Berrien-Brooks-Calhoun-Clay-Colquitt-Cook-Decatur-Dougherty-
Early-Grady-Irwin-Lanier-Lee-Lowndes-Miller-Mitchell-
Quitman-Randolph-Seminole-Terrell-Thomas-Tift-Turner-Worth.
FL...Freeze Warning until 9 AM EST /8 AM CST/ this morning for
Calhoun-Central Walton-Coastal Bay-Gadsden-Holmes-Inland
Bay-Inland Dixie-Inland Franklin-Inland Gulf-Inland
Jefferson-Inland Taylor-Inland Wakulla-Inland Walton-
Jackson-Lafayette-Leon-Liberty-Madison-South Walton-
Washington.
GM...None.
&&
$$
SYNOPSIS/SHORT TERM/MARINE...MROCZKA
LONG TERM/AVIATION/FIRE WX...CAMP
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1140 PM CST WED NOV 30 2011
...UPDATE TO AVIATION...
.DISCUSSION...
SHORT RANGE FORECAST (TONIGHT AND THURSDAY)...
20Z WATER VAPOR IMAGERY AND ASSOCIATED 500 MB RUC ANALYSIS SHOWS A
MID/UPPER LEVEL TROUGH OVER THE APPALACHIAN MOUNTAINS...WITH ANOTHER
H5 LOW DIVING SOUTHWARD THROUGH THE NORTHERN ROCKIES. BETWEEN THE
TWO TROUGHS IS A FLATTENED UPPER RIDGE OVER THE CENTRAL PLAINS WHICH
HAS BROUGHT FAIR CONDITIONS TO THE AREA. SOUTHERLY FLOW ALONG THE
EASTERN EDGE OF A DEEPENING SURFACE TROUGH ADVECTED WARM AIR INTO
NORTHEAST KANSAS...ALLOWING TEMPS TO REACH THE MID 50S ACROSS MUCH
OF THE AREA. EXPECT THE SURFACE TROUGH TO PUSH SOUTHEASTWARD AHEAD
OF AN ADVANCING SURFACE RIDGE...WHICH WILL BRING A COLD FRONT
THROUGH THE AREA BY MID DAY ON THURSDAY. EXPECT COOLER/DRYER AIR TO
MOVE IN BEHIND THE COLD FRONT FOR THURSDAY...ESPECIALLY FOR AREAS
ACROSS NORTH CENTRAL KANSAS WHICH WILL SEE THE FRONTAL PASSAGE
BEFORE PEAK HEATING. AREAS OF EASTERN KANSAS MAY SEE ANOTHER MILD
DAY AS SOUTHERLY FLOW SHOULD PERSIST THROUGH MUCH OF THE EARLY
AFTERNOON BEFORE THE FRONTAL PASSAGE IN THE EARLY EVENING. EXPECT
STRATUS TO BUILD IN BEHIND THE FRONT WHICH COULD POSSIBLY BRING SOME
SCATTERED SPRINKLES OR POSSIBLY SOME SNOW FLURRIES TO AREAS OF NORTH
CENTRAL KANSAS ON THURSDAY.
LEIGHTON
LONG TERM...THU NIGHT THROUGH NEXT WEDS.
FCST FOCUS REMAINS ON THE EVOLUTION OF STORM SYSTEM FRI INTO SAT.
RECENT MODEL GUIDANCE AND TRENDS CONTINUE TO SUGGEST A SLOWER
TRACK THAN THAT INDICATED BY THE NAM. GFS/ECMWF ARE THE FAVORED
MODELS FOR THIS FCST.
INITIAL MODIFIED POLAR AIRMASS WILL SETTLE INTO THE AREA THU
NIGHT WITH LIGHT WINDS AND SEASONABLY COLD TEMPS. BY FRI
AM...SOUTHERLY SFC WINDS WILL DEVELOP AS THE WESTERN U.S. LONGWAVE
TROUGH BEGINS TO BECOME PROGRESSIVE. LIFT WILL INCREASE THROUGH
THE DAY WITH SATURATION AND PRECIP DEVELOPMENT EXPECTED BY FRI
NIGHT. THERMAL PROFILES SUGGEST MAINLY RAIN EXCEPT FOR THE
NORTHWEST THIRD OF THE CWA WHERE DEPENDING ON THE WET BULB TEMPS
THERE MAY BE A RISK FOR FREEZING RAIN. GFS RAW MODEL NEAR SFC
TEMPS ARE WARMER THAN THE NUMERICAL MODEL GUIDANCE WHICH SUGGESTS
LOWS IN THE UPPER 20S TO LOWER 30S ACROSS THE NW THIRD SO
CONFIDENCE IN ICE THREAT REMAINS LOW AT THIS TIME. RIGHT NOW AREAS
ROUGHLY FROM ABILENE TO SENECA AND NW COULD SEE FREEZING PRECIP
FRI NIGHT. GFS CONTINUES TO WARM BOUNDARY LAYER TEMPS UP EARLY SAT
SUCH THAT ANY FZRA/ICE RISK SHOULD DECREASE HOWEVER WIDESPREAD
RAIN...SOME HEAVY SHOULD PERSIST ACROSS THE AREA AS THE UPPER
TROUGH MOVES THROUGH THE AREA AND THE SFC LOW TRACKS ACROSS
EASTERN KS. PRECIP SHOULD MIX WITH OR CHANGE TO SLEET OR SNOW FROM
WEST TO EAST BY LATER SAT/SAT NIGHT AS COLDER AIR ARRIVES ON THE
BACK SIDE OF THE SYSTEM. HOWEVER GFS ALSO SHOWS A DRY SLOT LATER
SAT AFTERNOON WHICH COULD BRING A BREAK IN THE PRECIP AND WOULD
ALSO LIMIT THE SNOW THREAT ACROSS NORTH-CENTRAL KS.
ALL IN ALL...LOOK FOR ANOTHER ROUND OF WIDESPREAD HEAVY RAINS OF 1
TO 2.5 INCHES FRI NIGHT INTO SAT WITH WHAT APPEARS TO BE A LOW RISK
FOR FREEZING PRECIP FRI NIGHT ACROSS PARTS OF THE AREA.
THE PATTERN LOOKS QUITE ACTIVE FOR THE REGION INTO NEXT WEEK WITH
ADDITIONAL POLAR COLD FRONTS EXPECTED TO DRIVE SOUTHWARD THROUGH
THE PLAINS. THE ACTUAL LONGWAVE TROUGH AXIS MAY NOT PASS THROUGH
THE REGION UNTIL MID WEEK SO CLOUDS/SOME LOW PRECIP CHCS MAY
LINGER ACROSS SOUTHERN KS BUT IT LOOKS DRY BUT COLD ACROSS NE KS.
CO
&&
.AVIATION...
VFR CONDITIONS TO CONTINUE THROUGH AT LEAST 23Z TODAY...THEN LOWER
STRATUS MAY MAKE A RUN AT THE TERMINAL LOCATIONS. MODELS BRING A
NARROW STRIP OF MVFR CIGS INTO AREA AFTER 23Z AND CONFIDENCE NOT
HIGH ENOUGH AT THIS TIME TO GO WITH A PROLONGED PERIOD OF MVFR
CIGS AFTER 02/00Z. WINDS SHIFT TO THE NORTH IN THE 14Z-16Z PERIOD
TODAY...THEN REMAIN NEAR 10 KTS THROUGH THE REST OF THE PERIOD.
53
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
326 AM EST THU DEC 1 2011
.SYNOPSIS...
EXCEPT FOR A PASSING SHOWER NORTH OF INTERSTATE 80 FRIDAY
AFTERNOON...EXPECT DRY AND SEASONABLE WEATHER UNTIL A COLD FRONT
APPROACHES THE REGION SUNDAY NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
LOWER CLOUDS HAVE STUBBORNLY PERSISTED ALONG THE PA/WV/MD RIDGES AND
ACROSS PORTIONS OF CENTRAL OH. THESE CLOUDS SHOULD QUICKLY DIMINISH
AFTER SUNRISE AS DAYTIME HEATING MIXES DRIER AIR TO THE SURFACE.
WITH HIGH PRESSURE IN CONTROL...EXPECT LIGHT WINDS AND MOSTLY SUNNY
SKIES TODAY. SOME CLOUD COVER WILL MOVE IN LATE TONIGHT AS A WEAK
FRONT APPROACHES FROM THE WEST.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
A WEAK FRONT WILL MOVE ACROSS THE REGION FRIDAY. STILL APPEARS THAT
THE PRIMARY IMPACTS WILL BE INCREASED CLOUD COVER AND A WIND SHIFT.
MODELS INDICATE THAT AN ISOLATED SHOWER COULD OCCUR NORTH OF
INTERSTATE 80...BUT MODELS HAVE BEEN CONSISTENT OVER THE LAST FEW
DAYS SHOWING NO THREAT OF PRECIP SOUTH OF THE INTERSTATE. THE
INFLUENCE OF HIGH PRESSURE WILL RETURN FRIDAY NIGHT...CLEARING SKIES
OUT. SOUTHERLY WINDS ON SATURDAY WILL ALLOW FOR A SLIGHT
WARMUP...BRING HIGHS A FEW DEGREES ABOVE NORMAL. CLOUDS WILL
INCREASE ONCE AGAIN SATURDAY NIGHT AS A MORE POTENT FRONT MOVES
ACROSS THE PLAINS. WILL INCREASE POPS TO HIGH CHANCE ACROSS OHIO BY
SUNDAY AFTERNOON.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
NEXT SYSTEM PROGGED TO APPROACH THE REGION LATE SUNDAY. CURRENTLY
MODELS INDICATE A SERIES OF SHORTWAVES DEEPENING THE POSITIVELY
TILTED UPPER LEVEL TROUGH AND ALLOWING FOR VERY COLD H850
TEMPERATURES OVER CANADA TO SINK SOUTHWARD TO AS FAR AS
MISSISSIPPI VALLEY BY TUESDAY. HAVE BUMPED POPS UP TO LIKELY FOR
SUNDAY NIGHT INTO MONDAY WITH GOOD CONSENSUS BETWEEN 01/00Z
GFS/ECMWF/NAEFS...AND WILL CONTINUE CHANCE POPS FOR MONDAY NIGHT
INTO TUESDAY. WITH THE H850 TEMPERATURES REACHING -12C AND
NORTHWEST FLOW...HIGH TEMPERATURES COULD BE 10 DEGREES BELOW
NORMAL TUESDAY AND WEDNESDAY.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
PER RECENT SURFACE AND IR SATELLITE DATA, THE TWO DISTINCT BANDS OF
MVFR STRATUS ACROSS THE UPPER OHIO VALLEY, HAVE EXPANDED IN COVERAGE
SINCE MIDNIGHT. THE FIRST BAND WAS NEAR THE MOUNTAINS AND LIKELY
CAUSED BY A CHANNELING OF UPSLOPE FLOW. THE SECOND BAND, POSSIBLY
CAUSED BY NOCTURNAL COOLING OF TRAPPED MOISTURE BENEATH A
STRENGTHENING LOWLEVEL SUBSIDENCE INVERSION, EXTENDED FROM KMFD
SOUTHEASTWARD TO KMGW. MOST OF THE RECENT EXPANSION HAS OCCURRED
OVER OHIO AND NEAR THE INTERSECTIONS OF THE TWO BANDS OVER NORTHERN
WEST VIRGINIA.
PER RECENT HRRR MODEL OUTPUT, EXPECT MVFR STRATUS TO PERSIST INTO
14Z, WHERE IT HAS BEEN OCCURRING. NEARBY TAF SITES, LIKE KHLG AND
KZZV, MAY EXPERIENCE AN INCREASE IN STRATUS BEFORE THEN ALSO. OTHER
SITES LIKE KZZV OR KDUJ MAY SEE MVFR FOG DEVELOPMENT ALSO.
SOME FOG CAN ALSO DEVELOP IN THE RIVER VALLEYS, AS THE AIR
TEMPERATURES ARE ALMOST 20 DEGREES COLDER THAN NEARBY WATER
TEMPERATURES IN THE MID 40S. SURFACE WINDS OVER 3 KTS MAY PRECLUDE
THE FOG FROM EXPANDING TO AFFECT NEARBY TAF SITES.
BY 15Z, EXPECT VFR CLEAR FOR ALL SITES, TO BE MAINTAINED THROUGH
TONIGHT.
OUTLOOK...FRIDAY THROUGH MONDAY...
PREVALENT VFR THROUGH SATURDAY, EXCEPT NEAR I-80 LATE FRIDAY DUE TO
POSSIBLE RESTRICTIONS WITH SCATTERED COLD FRONTAL SHOWERS. MORE
WIDESPREAD RESTRICTIONS STARTING LATE SUNDAY WITH INCOMING MIDWEST
COLD FRONTAL BAND OF SHOWERS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
104 AM EST THU DEC 1 2011
.SYNOPSIS...
AS LOW PRESSURE EXITS TO THE NORTHEAST... SKIES WILL GENERALLY
CLEAR OVERNIGHT. HIGH PRESSURE WILL KEEP THE REGION COOL AND DRY
INTO THE WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
06Z UPDATE PRIMARILY FOR CLOUD COVER. A RING OF LOW CLOUDS HAS
DEVELOPED FROM BRADFORD SOUTH TO OAKLAND...AND BACK WEST TO
ZANESVILLE. SOME MOISTURE FROM YESTERDAYS RAINFALL MAY STILL BE
TRAPPED IN LOWEST LEVELS IN THESE LOCATIONS. CURRENT FORECAST HAS
THESE CLOUDS SLOWLY DISSIPATE...BUT CANNOT RULE OUT THE
POSSIBILITY THAT THE CLOUDS WILL PERSIST UNTIL AFTER SUNRISE AND
LOW LEVELS MIX OUT. THURSDAY WILL BE QUIET AS THE HIGH PRESSURE
STRENGTHENS OVER MUCH OF THE EASTERN U.S. KEPT TEMPERATURES CLOSE
TO NORMAL.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...
HIGH PRESSURE WILL MAINTAIN IT`S POSITION KEEPING MOST OF THE AREA
DRY THROUGHOUT THE PERIOD. A WEAK FRONT WILL DROP ACROSS THE
REGION LATE FRIDAY BUT AS MODELS HAVE INDICATED OVER THE LAST
COUPLE OF DAYS...THERE IS LIMITED MOISTURE TO SUPPORT MUCH IN THE
WAY OF PRECIPITATION. KEPT THE PREVIOUS FORECAST OF SLIGHT CHANCE
POPS NORTH OF THE I-80 AND LEFT IT DRY ELSEWHERE. LITTLE CHANGE
EXPECTED IN WEATHER FOR SATURDAY. TEMPERATURES SHOULD REMAIN NEAR
NORMAL FOR THIS TIME OF YEAR...GRADUALLY INCREASING TO ABOVE
NORMAL ON SATURDAY AS THE HIGH SLIDES OFF THE EAST COAST.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
NEXT SYSTEM PROGGED TO APPROACH THE REGION LATE SUNDAY. CURRENTLY
MODELS INDICATE A SERIES OF SHORTWAVES DEEPENING THE POSITIVELY
TILTED UPPER LEVEL TROUGH AND ALLOWING FOR VERY COLD H850
TEMPERATURES OVER CANADA TO SINK SOUTHWARD TO AS FAR AS
MISSISSIPPI VALLEY BY TUESDAY. THIS COULD ALLOW FOR WIDESPREAD
SNOW SHOWERS OVERNIGHT MONDAY INTO TUESDAY BUT GENERALLY KEPT POPS
IN THE CHANCE CATEGORY THROUGH THE PERIOD AT THIS TIME DUE TO
UNCERTAINTY. WITH THE H850 TEMPERATURES REACHING -12C AND
NORTHWEST FLOW...HIGH TEMPERATURES COULD BE 10 DEGREES BELOW
NORMAL TUESDAY AND WEDNESDAY.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
PER RECENT SURFACE AND IR SATELLITE DATA, TWO NARROW BANDS OF MVFR
STRATUS LIE ACROSS THE UPPER OHIO VALLEY. THE BAND NEAR THE
MOUNTAINS IS LIKELY BEING CAUSED BY UPSLOPE FLOW. NOT SO SURE ABOUT
WHAT IS CAUSING THE SECOND BAND THAT EXTENDS FROM KMFD TO KMGW. PER
RECENT NAM AND RUC MODEL PROFILES, THE BAND COULD BE RELATED TO
TRAPPED MOISTURE BENEATH A GROWING LOWLEVEL SUBSIDENCE INVERSION, AS
INDICATED BY A STRONG H8 TEMPERATURE GRADIENT ABOVE THE STRATUS.
SO USING A BLEND OF PERSISTENCE AND DIURNAL CLIMATOLOGY, HAVE
MAINTAINED MVFR STRATUS WHERE IT NOW OCCURRING, AND HAVE SPREAD
BROKEN MVFR STRATUS TO SOME NEARBY TAF SITES SUCH AS KHLG AND KFKL.
BY 14Z, EXPECT VFR CLEAR FOR ALL SITES, TO BE MAINTAINED THROUGH
TONIGHT.
OUTLOOK...FRIDAY THROUGH MONDAY...
PREVALENT VFR THROUGH SATURDAY, EXCEPT NEAR I-80 LATE FRIDAY DUE TO
POSSIBLE RESTRICTIONS WITH SCATTERED COLD FRONTAL SHOWERS. MORE
WIDESPREAD RESTRICTIONS STARTING LATE SUNDAY WITH INCOMING MIDWEST
COLD FRONTAL BAND OF SHOWERS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
421 AM EST THU DEC 1 2011
.SYNOPSIS...
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WNW FLOW OVER THE
UPR GRT LKS BTWN TROFFING CENTERED OVER HUDSON BAY AND UPR RDG IN
THE SRN PLAINS. POSITIVELY TILTED SHRTWV IN THE NRN PLAINS MOVING
THRU THIS FLOW AND ASSOCIATED SFC LO PRES/COLD FNT STRETCHING FM
NCNTRL WI SWWD INTO THE CENTRAL PLAINS AT 04Z IS BRINGING AN AREA OF
SN TO THE UPR GRT LKS. MAIN FORCING MECHANISMS APPEAR TO BE UPR DVGC
IN EXIT REGION OF SUPPORTING 100KT H3 JET MAX AND BAND OF H85-7 FGEN
ASSOCIATED WITH FRONTAL ZN...BUT DRYNESS OF LLVLS PER NEARBY 00Z
RAOBS/LACK OF SGNFT ISENTROPIC ASCENT/MODEST DEEP LYR QVECTOR CNVGC
IS GENERALLY LIMITING THE OVERALL SN INTENSITY. TO THE NW...
SPRAWLING SFC HI PRES CENTERED JUST W OF LK WINNIPEG IS PUSHING
COLDER AND EVEN DRIER LLVL AIR SWD...WITH H85 DWPT DOWN TO -21C/-27C
AT INL/YPL AT 00Z. H85 TEMPS WERE -6C AT INL BUT -18C AT THE PAS
MANITOBA JUST NW OF LK WINNIPEG. THE ARRIVAL OF THIS DRIER AIR IS
TENDING TO END THE PCPN OVER NRN MN EARLY THIS MRNG.
&&
.DISCUSSION...
MAIN FCST CONCERNS IN THE SHORT TERM ARE SN TRENDS/AMOUNTS AND
POTENTIAL FOR LES INTO TNGT. FOCUS IN THE LONGER TERM SHIFTS TO
POTENTIAL FOR MORE SN THIS COMING WEEKEND.
TDAY...EXPECT PERIODS OF -SN TO BE ONGOING AT FCST ISSUANCE MAINLY
OVER THE SE HALF OF THE CWA NEAR AXIS OF H85-7 FGEN AND BAND OF HIER
H85 DWPT CLOSER TO THE H85 FNT. ALTHOUGH THE ARRIVAL OF COLDER AIR
FM THE N...WITH H85 TEMPS FALLING TOWARD -9C AT 12Z OVER THE
KEWEENAW...WL BE SUFFICIENT TO GENERATE SOME LES...FAIRLY PROFOUND
DRYING IN THE H925-85 LYR AND GENERAL ACYC NATURE OF LLVL FLOW WL
TEND TO LIMIT THE DURATION AND INTENSITY OF THE SHSN. BEST CHC FOR
HIER LES ACCUMS LOOKS TO BE IN AN AREA FM MQT-MUNISING FAVORED BY
EXPECTED N WIND AND WHERE DEEPER MSTR IS PROGGED TO LINGER UNTIL
ABOUT NOON. LINGERING LES SHOULD DIMINISH FAIRLY STEADILY THIS AFTN
EVEN THOUGH QUITE A BIT OF SC SHOULD PERSIST WITH MOISTENING OFF LK
SUP. OTRW...EXPECT STEADY OR SLOWLY FALLING TEMPS THRU THE DAY WITH
THESE CLDS AND FALLING H85 TEMPS TO ARND -13C OVER THE NW LATER.
TNGT...WITH ARRIVAL OF SFC RDG AXIS/MORE ACYC BACKING FLOW...EXPECT
SKIES TO CLR OVER MOST OF THE CWA. THE LK CLDS WL BE MORE RESILIENT
OVER THE KEWEENAW AND E OF MUNISING IN AREAS EXPERIENCING OVERWATER
FETCH. ALSO KEPT LINGERING POPS FOR LES IN THESE AREAS...ESPECIALLY
OVER THE E WITH LONGER FETCH/MOISTENING TO OVERCOME DRY LLVLS. BUT
GENERAL DRYNESS/LARGER SCALE ACYC FLOW AS WELL AS GENERALLY POOR SN
GROWTH PARAMETER WITH DGZ ABV THE RELATIVELY SHALLOW MIXED LYR SUG
SN ACCUMS WL BE ON THE LGT SIDE. EXPECT THE LOWEST MIN TEMPS OVER
THE INTERIOR W HALF...WHERE THE LK MODERATION WL BE LEAST.
FRI...AS THE SFC HI PRES RDG SHIFTS TO THE E AND THE FLOW BACKS
SW... ANY LINGERING LES WL END IN THE MRNG AND GIVE WAY TO A GOOD
AMOUNT OF AFTN SUNSHINE. EVEN WITH THE GREATER INSOLATION...STABLE
NATURE OF FCST SDNGS WITHIN LLVL COLD AIR IN THE ARCTIC AIRMASS
INDICATES TEMPS WL NOT RISE ABV 32 AT MOST PLACES.
FRI NGT...STRONG SW FLOW BTWN HI PRES MOVING TOWARD NEW ENGLAND AND
APRCHG COLD FNT ATTENDANT TO SHRTWV/SFC LO TRACKING INTO HUDSON BAY
IS FCST TO DRAW MORE SGNFT MSTR TO THE N...WITH PWAT 150 TO 200 PCT
OF NORMAL BY 12Z. CONSIDERING THE STRONG SW FLOW /NAM SHOWS H85
WINDS UP TO 50 KTS/ AND MSTR RETURN...EXPECT MIN TEMPS TO BE HIER
THAN TNGT.
THIS WEEKEND...THE 00Z GFS/ECMWF AND 21Z SREF ARE IN GOOD AGREEMENT
ON INTERACTION BTWN ARCTIC BRANCH TROF IN CENTRAL CANADA AND
DISTURBANCE/MSTR WITHIN SRN BRANCH SW FLOW IN THE CONUS ON NW FLANK
OF UPR RDG OFF THE SE COAST. SO USED A BLEND OF THIS GUIDANCE TO
POPULATE GRIDS. THESE MODELS SHOW A LO PRES WAVE DVLPG ON FNT
PUSHING ACRS THE CWA SAT NGT...WITH CENTER OF LO PRES MOVING ACRS
NRN LK MI AND INTO SE ONTARIO ON SUN. TENDED TOWARD THE HIER LIKELY
POPS OVER THE SE HALF OF THE CWA...WHERE THE MODELS INDICATE AS MUCH
AS 3 TO 6 INCHES OF SN MAY ACCUMULATE ON SAT/SAT NGT UNDER UPR DVGC/
H85-7 FGEN IN RRQ OF JET MAX OVER ONTARIO IN CONFLUENCE ZN BTWN THE
2 BRANCES ON THE COLD SIDE OF SFC FRONTAL BNDRY...EVEN IF SOME RA
MIXES WITH THE PCPN NEAR LK MI. TENDED TO MAINTAIN HIER POPS ON SUN
OVER THE NCNTRL THAN INDICATED BY ALL BLEND GUIDANCE CONSIDERING THE
POTENTIAL FOR LINGERING LK ENHANCEMENT WITH SHARPER CYC NNW FLOW
SHOWN BY THE MOST CONSISTENT 00Z ECMWF.
&&
.AVIATION /FOR 06Z TAF ISSUANCE/
NORTHERLY WINDS TO INCREASE OVERNIGHT AS HIGH PRESSURE BUILDS INTO
THE REGION BEHIND EXITING LOW PRESSURE TROUGH. AT FORECAST
ISSUANCE...TRANSITION FROM SYNOPTIC SNOWFALL TO LES OCCURRING AS
WINDS BECOME NORTHERLY. AT KIWD...CIGS TO HOLD IN MVFR THROUGH 12Z
WHILE KSAW AND KCMX TO SEE CIGS TO BOUNCE BETWEEN MVFR AND VFR WITH
DEVELOPING LES. OCCASIONAL IFR VSBYS EXPECTED AT BOTH KIWD AND KCMX
WITH LES DEVELOPMENT. INTRUSION OF DRIER AIR AND LOWERING OF
INVERSION HEIGHTS AS COLD AIR ADVECTION INCREASES SHOULD BRING AN
END TO THE -SHSN BY 12Z OUT WEST AND SHORTLY THEREAFTER AT KSAW.
AFTER 12Z...VFR CONDITIONS TO PREVAIL AT ALL SITES THROUGH THE END
OF THE FORECAST.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
AN ELONGATED LOW PRESSURE TROUGH FROM THE CENTRAL PLAINS TO FAR
EASTERN LAKE SUPERIOR WILL MOVE EAST TODAY. IN ITS WAKE...HIGH
PRESSURE OVER THE NORTHERN PLAINS WILL EXTEND A RIDGE OVER LAKE
SUPERIOR THROUGH FRIDAY MORNING...SINKING SOUTHEASTWARD TO THE
CENTRAL PLAINS. ON FRIDAY THE HIGH WILL MAKE ITS WAY TO THE
NORTHEASTERN STATES. MEANWHILE...LOW PRESSURE SYSTEM OVER HUDSON BAY
WILL DRAG A TROUGH ACROSS LAKE SUPERIOR SATURDAY AFTERNOON THROUGH
SATURDAY NIGHT. AHEAD OF THE TROUGH...EXPECT SOME SOUTHWEST GALE
FORCE GUSTS TO 35 KNOTS FRIDAY AFTERNOON INTO EARLY SATURDAY. HELD
OFF ON ISSUING ANY GALE HEADLINES SINCE GUSTS WILL ONLY MARGINALLY
MEET GALE CRITERIA. A LOW PRESSURE SYSTEM WILL TAKE SHAPE OVER THE
PLAINS SATURDAY NIGHT AND MERGE WITH THE TROUGH ON SUNDAY MORNING AS
IT REACHES LAKE MICHIGAN. THIS LOW WILL MOVE JUST EAST OF LAKE
SUPERIOR ON SUNDAY AFTERNOON AND REACH QUEBEC BY SUNDAY NIGHT.
ANOTHER LOW WILL DROP FROM ALBERTA INTO MINNESOTA SUNDAY
NIGHT...BEFORE MERGING WITH THE LINGERING TROUGH EAST OF LAKE
SUPERIOR BY MONDAY EVENING. THERE IS INCREASED UNCERTAINTY WITH
RESPECT TO WIND DIRECTIONS AND SPEEDS...AND THEREFOR WAVE HEIGHTS
STARTING SUNDAY EVENING. THE UNCERTAINTY IS DUE TO VARIABILITY
BETWEEN FORECAST MODELS ON THE TRACK AND STRENGTH OF THE LOW
PRESSURE SYSTEM COMING IN FROM THE WEST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...KC
DISCUSSION...KC
AVIATION...RJT
MARINE...TITUS
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1149 PM CST WED NOV 30 2011
.AVIATION... /06Z TAF ISSUANCE/
SNOW IS SINKING SOUTHEAST IN THE WAKE OF THE COLD FRONT A LITTLE
FASTER THAN PREVIOUSLY FORECAST. HAVE SPED UP THE LOW MVFR
CEILINGS AND VISIBILITIES INTO KRWF-KMSP-KEAU AS A RESULT. THE
BAND OF SNOW WILL SHIFT SOUTH OF THE TWIN CITIES BY 12Z BUT
CONTINUE ACROSS KEAU THROUGH 15Z. MVFR CEILINGS WILL BREAKUP FROM
NORTHWEST TO SOUTHEAST FROM LATE MORNING THROUGH THE EARLY
AFTERNOON AS STRONG LOW LEVEL RIDGING BUILDS IN. NORTH TO
NORTHWEST WINDS THURSDAY MORNING AROUND 12 KNOTS WITH GUSTS TO 18
KNOTS. LIGHT WEST WINDS AND SKC FOR THURSDAY NIGHT.
KMSP...BEST FORCING WILL BE MOVING ACROSS THE AIRFIELD THROUGH
09Z. LOW MVFR CEILINGS LIKELY ALONG WITH 2SM -SN BR. SOME THREAT
FOR CEILINGS TO INTERMITTENTLY DROP BELOW 010 THROUGH DAYBREAK.
CONDITIONS IMPROVING FROM MID MORNING ONWARD AS RIDGING BUILDS
IN. WINDS WILL BE THE STRONGEST DURING THE MORNING WITH NORTH AT
15 KNOTS COMMON. SKC WITH LIGHT WNW WINDS THURSDAY NIGHT.
&&
.DISCUSSION... /ISSUED 312 PM CST WED NOV 30 2011/
TONIGHT THROUGH THURSDAY...AT THE SFC A WEAK COLD FRONT WILL
SLOWLY GLIDE S ACRS SRN MN/SW WI THROUGH THE OVERNIGHT HOURS INTO
THU MRNG. AS IT DROPS S...A RELATIVELY WEAK AREA OF LOW PRESSURE
IS EXPECTED TO DEVELOP ALONG IN INVOF MN/IA BORDER. FAIRLY DEEP
MOISTURE...AS SHOWN BY AN EXTENSIVE CLOUD SHIELD ON VIS SAT
IMAGERY AND RATHER MOIST RUC SOUNDINGS...IS AVAILABLE FOR A DECENT
MIDLVL SHORTWAVE TROUGH AXIS TO PRODUCE PRECIP MAINLY AFTER
MIDNIGHT AND THROUGH SUNRISE. TAKING THE FORM OF ALL SNOW... WILL
LOOK FOR ENOUGH QPF TO PRODUCE ONE HALF TO ONE AND A HALF INCHES
OF SNOW WITH THE HEAVIEST OF THE SNOW OCCURRING DURING THE MORNING
COMMUTE HOURS. THE GREATER OF THE SNOW ACCUMULATIONS WILL EAST AND
SOUTH OF THE TWIN CITIES METRO. ALTHOUGH CONVECTIVE SNOWS ARE NOT
APPARENT ON EVEN SHORT-TERM MODELS PARTICULARLY WITH SFC
CONVERGENCE AND LIFT RATHER WEAK...THE UPPER LEVEL SUPPORT
AVAILABLE DOES NOT RULE OUT AN ISOLATED BURST OF HEAVIER SNOW THAT
COULD PRODUCE UP TO 2 INCHES IN A SHORT AMOUNT OF TIME...MAINLY
OVER WRN WI WHERE JET DYNAMICS LOOK TO POTENTIALLY ENHANCE PRECIP
THURSDAY MORNING. THE PRECIP WILL GRADUALLY TAPER OFF DURING THE
LATE MORNING THROUGH AFTERNOON HOURS TOMORROW WITH VERY LITTLE
LEFT BY LATE AFTERNOON. AS FOR TEMPERATURES...THE POTENT COLD
FRONT WILL EFFICIENTLY LEAD THE WAY FOR H85 TEMPS IN THE -7 TO -10
DEG C RANGE TO DROP THROUGH THE REGION DURING THE DAY TOMORROW...
MAKING FOR A VERY SMALL DIURNAL RANGE FROM LOW TEMPS TONIGHT TO
HIGHS TMRW. LOWS TONIGHT WILL RANGE FROM THE LWR 20S NW TO AROUND
30 SE AND IN THE METRO...FOLLOWED BY HIGHS THU FROM THE MID 20S NW
TO THE LWR 30S SE.
THURSDAY NIGHT THROUGH SUNDAY...SKIES WILL SLOWLY CLEAR OUT THU
NIGHT INTO FRI THE UPPER LEVEL TROUGH DROPS S OF THE REGION AND A
BUBBLE HIGH PRES RIDGE MOVES ACROSS THE NRN PLAINS INTO THE GREAT
LAKES. AT THE SFC...A SPOKE OF HIGH PRES EXTENDING NE FROM THE
CENTRAL PLAINS WILL ROTATE THROUGH...ALLOWING FOR DECENT
RADIATIONAL COOLING CONDITIONS THU NIGHT AS WINDS DROP TO BELOW 7
MPH. LOWS WILL FALL TO THE UPPER SINGLE DIGITS TO THE MID TEENS.
EVEN WITH THE CLEAR SKIES CONTINUING ON FRI AND SFC FLOW TURNING
MORE SLY...NW TO W UPPER FLOW AND H85 TEMPS ARND -5 DEG C WILL
KEEP HIGHS ON FRI JUST BELOW FREEZING. THE WEATHER STORY BECOMES
VERY INTERESTING FRI NIGHT THROUGH SAT NIGHT AS AS UPPER LEVEL LOW
CHURNING IN THE SOUTHWEST BECOMES CAUGHT UP IN A NORTHERN STREAM
LONGWAVE TROUGH AXIS PUSHING THRU WRN CANADA AND THE NRN PLAINS
STATES. BOTH UPPER SYSTEMS INTERACT BUT IN PIECES...AND A FEW
PIECES OF ENERGY WILL SHIFT NE FROM THE SOUTHWEST TWD THE GREAT
LAKES SAT AS CYCLOGENESIS OCCURS OVER THE TX PANHANDLE. THIS
NEWLY-GENERATED SFC LOW WILL RACE NE LATE SATURDAY THROUGH SAT
NIGHT BUT THE BIGGER PROBLEM IS HOW CLOSE AN UPPER SHORTWAVE
TROUGH AXIS COMES TO INTERACT WITH IT. MOISTURE TRANSPORT AHEAD OF
THIS NEW SFC LOW INCREASES AND THE INCOMING UPPER TROUGH WILL
ENHANCE LIFT. GIVEN THE COLD TEMPERATURES IN PLACE...P-TYPE ISSUES
WILL NOT BE PRESENT FOR THE WFO MPX CWFA AS PRECIP WOULD BE ALL
SNOW. THERE IS STILL MUCH MODEL DISAGREEMENT IN THE PLACEMENT OF
THE MAIN PLAYERS INVOLVED...AND THIS IS RELAYED VIA MODEL SNOWFALL
ACCUMS WHICH COULD BE UP TO A COUPLE OF INCHES TO OVER 6 INCHES
WITH THE HIGHEST AMOUNTS FOR SOUTHERN AND EASTERN PORTIONS OF THE
COVERAGE AREA. HAVE NUDGED POPS INTO THE LIKELY CATEGORY FOR THOSE
AREAS...TRENDING DOWN GOING WEST AND NORTH...AND HAVE KEPT
SNOWFALL AMOUNTS CAPPED AT 4 INCHES FOR FAR SRN AND ERN FRINGES
WITH NO SNOW EXPECTED FOR THE NWRN TIERS. THIS SYSTEM QUICKLY
EJECTS TO THE E SAT NIGHT INTO SUN...ALLOWING FOR AT LEAST PARTIAL
CLEARING DURING THE DAY SUNDAY BEFORE ANOTHER AREA OF LOW PRESSURE
DROPS IN FROM MANITOBA LATE SUN INTO SUN NIGHT. THERE IS POTENTIAL
FOR VERY LIGHT ACCUMS OVER NRN TIERS OF THE COVERAGE AREA BUT WITH
SO MUCH UNCERTAINTY WITH THIS SATURDAY SYSTEM...IT IS DIFFICULT TO
PINPOINT THINGS WITH THE LATE SUNDAY SYSTEM SO HAVE KEPT POPS IN
THE SLGT CHC CATEGORY. TEMPERATURES WILL RUN NEAR TO SLIGHTLY
ABOVE NORMAL THRU FRI...THEN DROP TO SLIGHTLY BELOW NORMAL OVER
THE WEEKEND.
MONDAY THROUGH WEDNESDAY...THE AFOREMENTIONED LOW ON SUNDAY WILL
MOVE INTO THE GREAT LAKES MONDAY...FOLLOWED BY RIDGING BOTH AT THE
SFC AND ALOFT FOR THE START OF NEXT WEEK. COLDER PUNCHES OF AIR
DROPPING S FROM NRN-CENTRAL CANADA WILL KEEP TEMPS BELOW NORMAL
FOR THE FIRST HALF OF NEXT WEEK. HAVE KEPT A PREDOMINANTLY DRY
FORECAST GOING DUE TO THE LACK OF BONA FIDE SYSTEMS PROGGED FOR
THIS PERIOD.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
RAH/TRH
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1038 PM MST WED NOV 30 2011
.AVIATION...06Z TAFS
SNOW HAS BECOME MORE WIDESPREAD THE PAST FEW RADAR IMAGES ACROSS
SOUTHERN WYOMING. STRONG THREE HOUR PRESSURE TENDENCIES OBSERVED
OVER NORTHERN AND NORTHWESTERN WYOMING AT 03Z STILL AN INDICATION
THAT STRONG WINDS ARE GOING TO MATERIALIZE. MEDICINE BOW PROFILER
HAS SHOWN AN INCREASE IN NORTHEASTERLY WINDS TO 25KTS AT 05Z.
FLIGHT CONDITIONS HAVE GONE DOWN IN AREAS WHERE SNOW HAS
DEVELOPED. WITH THE SNOW AREA CONTINUING TO EXPAND...DO EXPECT
IFR/LIFR CONDITIONS TO CONTINUE. THE EXCEPTION MAY BE LARAMIE
WHERE WINDS ARE BECOMING MORE DOWNSLOPING OFF THE WESTERN LARAMIE
SLOPES. WILL NEED TO CONTINUE MONITORING. GENERALLY FOLLOWED
LATEST HRRR GUIDANCE ON TIMING OF LOWERING CONDITIONS OVERNIGHT.
CONDITIONS EXPECTED TO IMPROVE LATE MORNING INTO THE AFTERNOON HOURS.
CLAYCOMB
&&
.PREV DISCUSSION... /ISSUED 816 PM MST WED NOV 30 2011/
UPDATE...
WINTER STORM STILL APPEARS TO BE ON TRACK ACROSS MUCH OF SOUTHEAST
WYOMING AND THE WESTERN NEBRASKA PANHANDLE IN THE WAKE OF A STRONG
COLD FRONT MOVING RAPIDLY SOUTHEASTWARD ACROSS THE REGION. THIS
FRONT HAS ALREADY CLEARED OUR FORECAST AREA...WITH 3-HOUR PRESSURE
RISES RANGING FROM 3 TO 5 MILLIBARS OVERSPREADING A LARGE PORTION
OF CENTRAL AND EASTERN WYOMING. NORTH TO NORTHEAST WINDS HAVE
INCREASED TO BETWEEN 20 AND 30 MPH ACROSS MOST AREAS...WITH GUSTS
AS HIGH AS 35 MPH. THESE WINDS SHOULD PERSIST...AND PERHAPS
INCREASE OVERNIGHT AS H7-H75 WINDS INCREASE TO BETWEEN 35 AND 40
KTS...ESPECIALLY OVER OUR MOUNTAIN ZONES.
RECENT TRENDS IN RADAR AND INFRARED SATELLITE IMAGERY/COOLING
CLOUD TOPS INDICATE SNOW IS BEGINNING TO INCREASE IN COVERAGE AND
INTENSITY ACROSS MUCH OF SOUTHEAST WYOMING. THE INHERITED WINTER
STORM WARNING LOOKS GOOD WITH THE POTENTIAL FOR SIGNIFICANT
BLOWING AND DRIFTING SNOW DESPITE SNOW AMOUNTS LIKELY STRUGGLING
TO REACH WARNING CRITERIA. HIGH SNOW RATIOS IN EXCESS OF 15 TO 1
ARE ALSO LIKELY AS H7 TEMPERATURES PLUNGE TO BETWEEN -10C AND
-15C...SO FRESH SNOW SHOULD BE EASY TO BLOW AROUND. THE LATEST
CONCERN IS THE NORTHERN LARAMIE RANGE...WITH NORTH-FACING SLOPES
BEING ESPECIALLY PRONE TO UPSLOPE ENHANCEMENT LATER TONIGHT. THIS
AREA IS BEING HIT HARD BY THE NAM AND ECMWF...WHICH SEEMS QUITE
REALISTIC GIVEN THE LOW-LEVEL FLOW REGIME. WITH 5 TO 10 INCHES OF
SNOW AND WIND GUSTS IN EXCESS OF 40 MPH...WE HAVE OPTED TO ADD OUR
FAR NORTHWEST MOUNTAIN ZONES TO THE CURRENT WINTER STORM WARNING. THE
SNOW AND BLOWING SNOW ADVISORY HAS ALSO BEEN EXPANDED TO INCLUDE
THE REMAINDER OF THE WESTERN NEBRASKA PANHANDLE...AND CONVERSE AND
NIOBRARA COUNTIES IN EAST CENTRAL WYOMING. WIND WILL BE THE
BIGGEST CONCERN ACROSS THESE AREAS AS VERY STRONG PRESSURE RISES
OVERSPREAD THE REGION BY DAYBREAK THURSDAY. MODEST SNOW
ACCUMULATIONS AND WINDS IN EXCESS OF 30 MPH SHOULD BE MORE THAN
SUFFICIENT FOR HAZARDOUS TRAVEL.
&&
PREV DISCUSSION... /ISSUED 202 PM MST WED NOV 30 2011/
SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT.
TONIGHT...THE FINAL DAY OF NOVEMBER WILL GO OUT LIKE A LAMB WITH
HIGH TEMPERATURES IN THE 40S AND 50S...WITH THE FIRST DAY OF
DECEMBER COMING IN LIKE A LION AS A STRONG COLD FRONT QUICKLY ROARS
THROUGH OUR COUNTIES BY EARLY EVENING. 3 HOURLY PRESSURE RISES OF 2
TO 7 MB OCCURRING ACROSS NORTHERN MONTANA WILL KEEP THE FRONT
BARRELING SOUTH.
CURRENT WINTER STORM WARNING AND WINTER WEATHER ADVISORY AREAS AND
TIMING LOOK GOOD BASED ON EXPECTED SNOWFALL AMOUNTS...AND ESPECIALLY
WITH THE COMBINATION OF BLOWING SNOW...REDUCED VISIBILITIES AND COLD
TEMPERATURES.
WIDESPREAD SNOW WILL DEVELOP THIS EVENING ACROSS SOUTHEAST WYOMING
AND SPREAD ACROSS WESTERN NEBRASKA LATE TONIGHT...LAGGING THE COLD
FRONT BY A FEW HOURS. STRONG SURFACE THROUGH 700 MB GRADIENTS WILL
PRODUCE BRISK NORTH WINDS DUE TO STRONG THICKNESS PACKING.
COMBINATION OF FALLING SNOW AND WINDS WILL PRODUCE AREAS OF BLOWING
SNOW AND VISIBILITIES NEAR ZERO.
THURSDAY...WIDESPREAD SNOW AND BLOWING SNOW CONTINUE IN THE MORNING
SOUTH OF A RAWLINS TO SCOTTSBLUFF LINE WITH SNOW TAPERING OFF TO THE
NORTH. IN THE AFTERNOON...SNOW WILL END IN THE NORTH WITH SNOW
DECREASING IN AREAL COVERAGE AND INTENSITY ACROSS OUR SOUTHERN
COUNTIES. MUCH COLDER WITH HIGHS IN THE TEENS AND 20S.
TOTAL MOUNTAIN SNOWFALL AMOUNTS WILL RANGE FROM 10 TO 14 INCHES...
WITH 4 TO 7 INCHES WEST OF A DOUGLAS TO CHEYENNE LINE AND 1 TO 4
INCHES ELSEWHERE.
THURSDAY NIGHT...VERY COLD WITH CLOUDS DECREASING AND FRESH SNOW
COVER. LOWS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO.
FRIDAY...SLIGHT WARMING TREND IN ADVANCE OF THE NEXT REINFORCING
SHOT OF COLD AIR...THOUGH LIMITED BY RESIDUAL SNOW COVER.
FRIDAY NIGHT...NEXT SHORTWAVE TROUGH ALOFT AND COLD FRONT WILL BRING
SNOW AGAIN SOUTH OF A DOUGLAS TO SIDNEY LINE...THOUGH SNOWFALL
AMOUNTS WILL BE MORE LIMITED WITH LESS MOISTURE AVAILABILITY AND
LESS LIFT.
LONG TERM...SATURDAY THROUGH WEDNESDAY...THE 12Z MEDIUM RANGE MODELS
ALL DEPICT A HIGHLY AMPLIFIED UPPER LEVEL PATTERN ACROSS THE LOWER
48. A POSITIVELY-TILTED MEAN TROUGH WILL EXTEND FROM HUDSON BAY IN
CANADA TO THE FOUR CORNERS REGION...WITH A MEAN UPPER RIDGE OVER
THE NORTHEASTERN PACIFIC. A SERIES OF SHORT WAVES WILL TOP THE RIDGE
AND DROP SOUTH/SOUTHEAST THROUGH CENTRAL AND SOUTHERN CANADA INTO
THE NORTH CENTRAL STATES DURING THE PERIOD...REINFORCING THE MEAN
TROUGH. THIS PATTERN WILL MAINTAIN BELOW NORMAL TEMPERATURES WITH
A FEW CANADIAN COLD FRONTAL PASSAGES. THE UPPER LEVEL SYSTEM
RESPONSIBLE FOR THE LIGHT SNOW ON SATURDAY WILL MOVE EAST INTO
THE PLAINS SATURDAY NIGHT. IT WILL BE COLDER ON SATURDAY IN THE
WAKE OF A COLD FRONT WITH BRISK NORTHERLY WINDS. SATURDAY NIGHT
WILL BE COLD BUT DRY. THE NEXT COLD FRONT AND UPPER LEVEL
DISTURBANCE DROPS QUICKLY SOUTH THROUGH THE HIGH PLAINS SUNDAY AND
SUNDAY NIGHT WITH CHANCES FOR LIGHT SNOW MAINLY ALONG AND WEST OF
THE LARAMIE RANGE. POST-FRONTAL AIRMASS IS MODIFIED SO TEMPERATURES
WILL NOT BE AS CHILLY AS THE PREVIOUS SYSTEM. THE UPPER FLOW
BACKS FROM NORTHERLY TO WESTERLY ON TUESDAY IN ADVANCE OF THE
NEXT POTENT SHORT WAVE ENTERING THE NORTHWEST TIER OF THE NATION.
DOWNSLOPING EAST OF THE LARAMIE RANGE WILL RESULT IN WARMER...MORE
SEASONAL TEMPERATURES. THE NEXT COLD FRONT MOVES SOUTHEAST ACROSS
CENTRAL AND EASTERN WYOMING WEDNESDAY WITH CHANCES FOR RAIN/SNOW
ALONG WITH COOLER TEMPERATURES FOR NORTHERN AND WESTERN PORTIONS
OF THE CWA.
FIRE WEATHER...NO FIRE WEATHER CONCERNS.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER STORM WARNING UNTIL 3 PM THURSDAY FOR WYZ103-WYZ104-
WYZ105-WYZ109-WYZ110-WYZ111-WYZ112-WYZ113-WYZ114.
WINTER STORM WARNING UNTIL 3 PM THURSDAY FOR WYZ115-WYZ116-
WYZ117-WYZ118-WYZ119.
WINTER WEATHER ADVISORY UNTIL 3 PM THURSDAY FOR WYZ101-WYZ102-
WYZ106-WYZ107-WYZ108.
NE...WINTER WEATHER ADVISORY UNTIL 3 PM THURSDAY FOR NEZ002-NEZ003-
NEZ019-NEZ020-NEZ021-NEZ054-NEZ055-NEZ095-NEZ096.
&&
$$
SHORT TERM...RUBIN
LONG TERM/AVIATION...JAMSKI
AREA FORECAST DISCUSSION...UPDATED
NWS TALLAHASSEE FL
645 AM EST Thu Dec 01 2011
UPDATED FOR 12Z TAF ISSUANCE
.SYNOPSIS...
07Z water vapor and H4 RUC analysis shows an active upper level
pattern across the CONUS this morning. Sharp troughing covers the
inter-mountain west with a potent shortwave at its base digging
southward over CA/NV. This energy is progged to close off over the
next several hours and stall. Further downstream the flow leaving
the southwestern states ridges northward across the Central
Plains/Middle and lower MS valley. Finally we find troughing about
to exit off the Atlantic seaboard. The base of this trough contains
a fairly sharp/potent shortwave that is just now exiting east of our
forecast area. Large scale subsidence on the backside of this
impulse is working to continue drying our our atmospheric column,
and will help contribute to abundant sunshine for our Thursday. The
KTLH 00Z sounding profile already showed an impressively low PW
values of 0.31" (only about 33% of climo for early December). With
the ongoing subsidence...would anticipate the 12Z profile to be even
lower. In fact both the GFS and NAM prog PW values down as low as
0.2" by sunrise.
At the surface,
1025mb ridge of high pressure is centered from the TN Valley to the
MS/AL border region. The influence of this ridge extends into our
forecast area with a weak gradient now in place. This weak gradient
has allowed winds to go very light/calm early this morning and
boundary layer decoupling appears to have already occurred at many
locations. Good radiational cooling within the decoupled layer has
allowed many stations to reach the freezing mark or lower this
morning. At this time the freeze warning appears on track and do not
anticipate making any significant changes to the forecast through
sunrise.
&&
.SHORT TERM (TODAY THROUGH SATURDAY)...
Today,
Pleasant day on tap after a cold start. Heights will rise over the
region in the wake of the departing shortwave trough. The rising
heights along with the building surface high building will lead to
stacked ridging dominating our weather by the end of the day. The
weak low level gradient and near solar minimum sun angle will not
lead to efficient mixing today. High temperatures will again end up
below normal despite abundant sunshine. Temperatures will struggle
into the lower 60s by mid-afternoon across a majority of the area,
with a few middle 60s down toward Perry, Mayo, and Cross City.
Tonight,
Clear skies, dry low levels, and the surface ridge axis still in
close proximity will allow for another fairly cold night. It does
not appear likely that we will see the areal coverage of freezing or
sub-freezing temperatures that are occurring this morning, nor does
it appear that we will see the durations of freezing temperatures.
Minimum temperature grids will show widespread lower to middle 30s
away from the immediate coast. These temperatures combined with the
light winds and small dewpoint depressions should still lead to
areas of frost development. The forecast will show this frost
potential for all areas expected to reach 35 degrees or lower.
Normally colder spots are forecast to briefly drop below freezing
(30-32F) around sunrise, however the overall coverage at this time
is not anticipated to warrant another freeze watch/warning event.
Friday Through Saturday,
Stacked ridging will remain in control of our weather providing dry,
seasonable, and slowly warming conditions into the first half of the
upcoming weekend. Temperatures Friday will rebound upward several
degrees from Thursday`s highs. Current grids will show mainly middle
to upper 60s, with lower 70s over the SE Big Bend Zones. Very dry
atmosphere will keep our skies sunny.
Strong high pressure will redevelop and build down the eastern
seaboard later Friday and Friday night. ECMWF/GFS both show surface
pressures with this high reaching 1036-1038mb over the mid-Atlantic
region. The effect for our region will be a significant tightening
of the gradient and resulting easterly flow. This easterly flow will
begin to transport low level Atlantic moisture back into the region.
Due to the tighter gradient and increased moisture, do not
anticipate the potential for freezing temps or likely even any frost
Friday night. It will still be cool, but the coldest inland temps
currently in the grids show mid/upper 30s. Temps warmer still will
be experienced along the coast from Wakulla County westward due to
the easterly/ESE flow.
More of the same for Saturday with perhaps a few-sct afternoon cu
field. More efficient mixing due to the tighter gradient will allow
temps to climb toward the lower 70s across much of the area.
&&
.LONG TERM (SUNDAY THROUGH NEXT THURSDAY)...
The Guidance is in decent agreement through Sunday night before
significant differences begin to arise. Through Sunday night, a
ridge will be in place over the Southeastern states, with dry
conditions and temperatures back near climo. A strong surface high
over New England will keep northeast flow in place across the region
Sunday and prevent temperatures from warming more significantly.
This high shifts well east by Monday, allowing for a more
substantial warm-up.
Significant model differences are evident by Monday through
Wednesday with the deep longwave trough over the central states. The
CMC and GFS are more progressive with the system and bring the
surface front through the region late Monday or early Tuesday. The
ECMWF and UKMET cutoff the tail of the trough leading to a much
slower progression, and a frontal passage Tuesday night or early
Wednesday. With significant uncertainty, have decided to take a
compromise of all the guidance, leading to a frontal passage on
Tuesday. A band of showers is expected with the front. However, the
bulk of the dynamics and lift are expected to pull northeast of the
area, with coverage on the decrease as the front crosses the region.
A much cooler airmass will spill into the region in the wake of the
front.
&&
.MARINE...
A ridge of high pressure will slide to the north of the forecast
waters through Friday. Northerly flow will come around to Northeast
and then east through this time. Cautionary level winds may briefly
decrease below headline criteria later this morning and into the
afternoon, but will increase back to cautionary levels tonight. The
gradient will tighten Friday night into Saturday as a new and
stronger area of high pressure builds down the eastern seaboard.
This tighter gradient will lead to a prolonged period of cautionary
to advisory level easterly flow through the upcoming weekend. The
next cold front will then approach from the west during the early
portion of next week.
&&
.AVIATION (through Friday 12z)...VFR conditions expected to prevail
through the forecast period.
&&
.FIRE WEATHER...
A dry airmass will remain in place over the region through Friday.
Cool temperatures will prevent RH values from dropping to critical
levels today. Slightly warmer temperatures on Friday will allow for
sub-35 percent RH across the Florida zones. However, ERC values are
expected to remain below 35. Therefore, no Fire Weather Watch is
planned at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 63 33 68 39 72 / 0 0 0 0 0
Panama City 62 40 67 47 68 / 0 0 0 0 0
Dothan 61 34 67 39 70 / 0 0 0 0 0
Albany 62 32 67 36 70 / 0 0 0 0 0
Valdosta 63 33 67 39 72 / 0 0 0 0 0
Cross City 67 36 71 41 75 / 0 0 0 0 0
Apalachicola 61 40 65 46 69 / 0 0 0 0 0
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...Freeze Warning until 8 AM CST this morning for Coffee-Dale-
Geneva-Henry-Houston.
GA...Freeze Warning until 9 AM EST this morning for Baker-Ben Hill-
Berrien-Brooks-Calhoun-Clay-Colquitt-Cook-Decatur-Dougherty-
Early-Grady-Irwin-Lanier-Lee-Lowndes-Miller-Mitchell-
Quitman-Randolph-Seminole-Terrell-Thomas-Tift-Turner-Worth.
FL...Freeze Warning until 9 AM EST /8 AM CST/ this morning for
Calhoun-Central Walton-Coastal Bay-Gadsden-Holmes-Inland
Bay-Inland Dixie-Inland Franklin-Inland Gulf-Inland
Jefferson-Inland Taylor-Inland Wakulla-Inland Walton-
Jackson-Lafayette-Leon-Liberty-Madison-South Walton-
Washington.
GM...None.
&&
$$
SYNOPSIS/SHORT TERM/MARINE...MROCZKA
LONG TERM/AVIATION/FIRE WX...CAMP
THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS...
/TODAY THROUGH SATURDAY/
EARLY THIS MORNING...UPPER LEVEL AND SFC RIDGING WERE THE DOMINANT
WEATHER FEATURES ACROSS THE REGION. THE UPPER LEVEL RIDGING WAS
CENTERED OVER THE GULF OF MEXICO REGION AND EXTENDED NORTH INTO THE MID
MS AND TN VALLEYS...WITH A DEPARTING TROUGH TO ITS EAST AND A CLOSED
LOW OVER THE SIERRA NEVADA/SOUTHWESTERN US. MEANWHILE...A SHORTWAVE
WAS OVER THE NORTHERN PLAINS AND NORTHERN ROCKIES.
TODAY AND TONIGHT...THE TROUGH OFF THE EASTERN SEABOARD WILL DEPART
FURTHER TO THE EAST WITH THE WESTERN CONUS CLOSED LOW DROPPING INTO
THE DESERT SW AND HEIGHTS INCREASE TO ITS NORTH DUE TO UPPER LEVEL
RIDGING BUILDING EAST FROM THE PACIFIC. MEANWHILE THE SHORTWAVE
NOW MOVING THROUGH THE PLAINS/NORTHERN ROCKIES WILL MOVE EAST RATHER
QUICKLY INTO THE GREAT LAKES BY THIS EVENING AND REACHING THE EASTERN
GREAT LAKES AND LOWER OH VALLEY BY DAWN ON FRIDAY. THIS SYSTEM WILL
CONTINUE PASSING BY TO OUR NORTH ON FRIDAY WITH HEIGHTS BRIEFLY INCREASING
FROM THE TN VALLEY NORTH INTO THE GREAT LAKES FROM FRI INTO FRIDAY
NIGHT IN ITS WAKE. AT THE SAME TIME...A SHORTWAVE WILL ENTER THE
NORTHERN ROCKIES AND PLAINS FROM FRI INTO FRIDAY NIGHT WHILE THE SW
US CLOSED LOW MEANDERS INTO THE FOUR CORNERS REGION. BY DAWN ON
SAT...A RATHER AMPLIFIED RIDGE IS EXPECTED WITH THE AXIS EXTENDING
FROM THE YUCATAN NORTH INTO THE MID ATLANTIC AND NORTHEAST...WITH A
MEAN TROUGH FROM CENTRAL CANADA WSW INTO THE SOUTHWESTERN US AND
SOUTHERN ROCKIES...THOUGH INDIVIDUAL SHORTWAVES ARE NOT EXPECTED TO
PHASED. HEIGHTS ARE PROGGED TO FALL OVER THE MS VALLEY AND LOWER OH
VALLEY LATE IN THE PERIOD AS THE TROUGH BEGINS TO SHIFT EAST.
HOWEVER...A DRY AIRMASS IS EXPECTED BELOW 500 MB FROM THE INFLUENCE
OF THE RIDGING JUST TO OUR EAST.
OTHER THAN SOME PATCHY VALLEY THROUGH AROUND DAWN OVER PORTIONS OF
THE CUMBERLAND...KENTUCKY AND BIG SANDY BASINS...THE RATHER SHOULD BE
RATHER UNEVENTFUL THROUGH THE PERIOD. THE DRY AIRMASS IN PLACE WILL
ONLY LEAD TO OCCASIONAL INCREASES IN HIGH CLOUDS WITH UPPER LEVEL
DISTURBANCES PASSING BY TO OUR NORTH THIS AM THROUGH EARLY AFTERNOON
AND AGAIN ON FRIDAY THROUGH FRIDAY NIGHT. A FEW MID CLOUDS MAY ALSO
PASS OVERHEAD FROM FRI INTO FRI NIGHT. ONLY SOME HIGH CLOUDS ARE
ANTICIPATED ON SAT AND THEY MAY BEGIN TO THICKEN AND LOWER LATE IN
THE PERIOD. OVERALL...THIS IS MAINLY JUST A TEMP...SKY AND DEWPOINT
FORECAST THROUGH THE PERIOD.
RIDGE/VALLEY TEMPS SPLITS SHOULD OCCUR THE NEXT COUPLE OF NIGHTS WITH
GRADUALLY MODERATING DAYTIME HIGHS THROUGH SAT. WITH MIXING TODAY...
VALLEY FOG IS NOT EXPECTED ON THU NIGHT OR FRI NIGHT.
.LONG TERM.../SATURDAY NIGHT THROUGH WEDNESDAY/
THE LATEST ROUND OF MODELS REMAINS IN FAIRLY GOOD AGREEMENT THROUGH
THE FIRST HALF OF THE PERIOD...THEN BEGINS TO DIVERGE WITH THE
DETAILS SURROUNDING A COLD FRONT APPROACHING THE OHIO VALLEY EARLY
NEXT WEEK. OVERALL...THE MEDIUM RANGE GUIDANCE CONTINUES TO SUPPORT
THE IDEA OF SHOWERS ASSOCIATED WITH THE FRONT MOVING INTO THE AREA
ON SUNDAY...KICKING OFF AN EXTENDED PERIOD OF RAIN THAT LOOKS TO
CONTINUE THROUGH AT LEAST TUESDAY AND POSSIBLY INTO TUESDAY NIGHT.
HOWEVER THE QUESTION REMAINS AS TO HOW FAST THE COLDER AIR WILL
BEGIN TO ARRIVE AND AT WHAT POINT WILL THE POTENTIAL FOR SNOW BECOME
AN ISSUE.
THE 01.00Z GEM LIES AT THE FASTER END OF THE SPECTRUM...BRINGING THE
COLDER AIRMASS INTO THE OHIO VALLEY AND ERN KY BY MONDAY NIGHT...BUT
WITH NO SUPPORT FROM THE OTHER MODELS HAVE DISCOUNTED THIS SOLUTION.
MEANWHILE THE 00Z ECMWF CONTINUES TO REPRESENT THE SLOWER END OF THE
SPECTRUM...HOLDING BACK THE ARRIVAL OF THE COLDER AIR ALOFT UNTIL
LATE WEDNESDAY...WHILE THE 00Z GFS REPRESENTS SOMEWHAT OF A MIDDLE
GROUND COMPROMISE...BRINGING THE COLDER AIR INTO THE REGION LATE
MONDAY NIGHT INTO TUESDAY. THE DISPARITY IN TIMING AT THIS POINT
LEADS TO A LOWER CONFIDENCE IN THE P TYPE AFTER MONDAY...AND WILL
CONTINUE TO ADVERTISE A MIXED BAG FROM MONDAY NIGHT ONWARD THROUGH
THE REMAINDER OF THE EVENT.
TEMPERATURES WILL ULTIMATELY BE DEPENDENT ON HOW EVENTS UNFOLD NEXT
WEEK...BUT GENERALLY FOLLOWED THE ALL BLEND CONSENSUS WITH A FEW
ADJUSTMENTS TO HIGHS ON MONDAY AND TUESDAY TO ACCOUNT FOR THE
EXPECTED PRECIPITATION AND TO LINE UP A LITTLE BETTER WITH THE
NEIGHBORS. THIS RESULTED IN HIGHS EARLY IN THE PERIOD RUNNING ABOVE
NORMAL FOR THE BEGINNING OF DECEMBER BEFORE TOPPING OUT IN THE 40S
BEHIND THE FRONT LATER IN THE PERIOD...WITH OVERNIGHT LOWS FOLLOWING
A SIMILAR TREND.
&&
.AVIATION.../18Z TO 18Z/...UPDATED
A SFC RIDGE OF HIGH PRESSURE SETTLING ACROSS THE OH AND TN VALLEY
WILL REMAIN IN PLACE OVER THE REGION DURING THE PERIOD AND BRING
VFR CONDITIONS THROUGH THE ENTIRE PERIOD. NO FOG IS FORECAST FOR THE
TAF STATIONS FOR TOMORROW.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...JP/JJ
LONG TERM....MB
AVIATION...JJ
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
759 AM EST THU DEC 1 2011
.SYNOPSIS...
EXCEPT FOR A PASSING SHOWER NORTH OF INTERSTATE 80 FRIDAY
AFTERNOON...EXPECT DRY AND SEASONABLE WEATHER UNTIL A COLD FRONT
APPROACHES THE REGION SUNDAY NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
A QUICK MORNING UPDATE HAS BEEN ISSUED THIS MORNING TO ACCOUNT FOR
THE LATEST TRENDS WITH PATCHES OF STRATOCUMULUS LINGERING ACROSS
EASTERN OHIO AND THE EASTERN RIDGES.
LOWER CLOUDS SHOULD QUICKLY DIMINISH AFTER SUNRISE AS DAYTIME
HEATING MIXES DRIER AIR TO THE SURFACE. WITH HIGH PRESSURE IN
CONTROL...EXPECT LIGHT WINDS AND MOSTLY SUNNY SKIES TODAY. SOME
CLOUD COVER WILL MOVE IN LATE TONIGHT AS A WEAK FRONT APPROACHES
FROM THE WEST.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
A WEAK FRONT WILL MOVE ACROSS THE REGION FRIDAY. STILL APPEARS THAT
THE PRIMARY IMPACTS WILL BE INCREASED CLOUD COVER AND A WIND SHIFT.
MODELS INDICATE THAT AN ISOLATED SHOWER COULD OCCUR NORTH OF
INTERSTATE 80...BUT MODELS HAVE BEEN CONSISTENT OVER THE LAST FEW
DAYS SHOWING NO THREAT OF PRECIP SOUTH OF THE INTERSTATE.
THE INFLUENCE OF HIGH PRESSURE WILL RETURN FRIDAY NIGHT...
CLEARING SKIES OUT. SOUTHERLY WINDS ON SATURDAY WILL PROMOTE A
SLIGHT WARMUP AND BRING HIGHS A FEW DEGREES ABOVE NORMAL.
CLOUDS WILL INCREASE ONCE AGAIN SATURDAY NIGHT AS A MORE POTENT
FRONT MOVES ACROSS THE PLAINS. WILL INCREASE POPS TO HIGH CHANCE
ACROSS OHIO BY SUNDAY AFTERNOON.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
NEXT SYSTEM PROGGED TO APPROACH THE REGION LATE SUNDAY. CURRENTLY
MODELS INDICATE A SERIES OF SHORTWAVES DEEPENING THE POSITIVELY
TILTED UPPER LEVEL TROUGH AND ALLOWING FOR VERY COLD H850
TEMPERATURES OVER CANADA TO SINK SOUTHWARD TO AS FAR AS
MISSISSIPPI VALLEY BY TUESDAY.
HAVE BUMPED POPS UP TO LIKELY FOR SUNDAY NIGHT INTO MONDAY WITH
GOOD CONSENSUS BETWEEN 01/00Z GFS/ECMWF/NAEFS...AND WILL CONTINUE
CHANCE POPS FOR MONDAY NIGHT INTO TUESDAY.
WITH THE H850 TEMPERATURES REACHING -12C AND NORTHWEST
FLOW...HIGH TEMPERATURES COULD BE 10 DEGREES BELOW NORMAL TUESDAY
AND WEDNESDAY.
&&
.AVIATION /13Z THURSDAY THROUGH MONDAY/...
RECENT SURFACE AND IR SATELLITE DATA CONTINUE TO SHOW PATCHES OF
MVFR STRATUS ACROSS EASTERN OHIO, SOUTHWESTERN PENNSYLVANIA, AND
ACROSS THE APPALACHIAN MOUNTAINS. THE STRATUS FORMED OVERNIGHT DUE
TO NOCTURNAL COOLING OF MOISTURE TRAPPED BENEATH A STRENGTHENING
SUBSIDENCE INVERSION. THE CLOUDS HAVE BEEN MOVING TOWARD THE
NORTHEAST. HOWEVER, EXPECT ALL THE STRATUS TO DISSIPATE BY 15Z
AS SUPPORTED BY RECENT HRRR MODEL OUTPUT. EXPECT VFR CLEAR TO
CONTINUE THROUGH TONIGHT.
OUTLOOK...FRIDAY THROUGH MONDAY...
PREVALENT VFR THROUGH SATURDAY, EXCEPT NEAR I-80 LATE FRIDAY DUE TO
POSSIBLE RESTRICTIONS WITH SCATTERED COLD FRONTAL SHOWERS. MORE
WIDESPREAD RESTRICTIONS STARTING LATE SUNDAY WITH INCOMING MIDWEST
COLD FRONTAL BAND OF SHOWERS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
651 AM EST THU DEC 1 2011
.SYNOPSIS...
EXCEPT FOR A PASSING SHOWER NORTH OF INTERSTATE 80 FRIDAY
AFTERNOON...EXPECT DRY AND SEASONABLE WEATHER UNTIL A COLD FRONT
APPROACHES THE REGION SUNDAY NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
LOWER CLOUDS SHOULD QUICKLY DIMINISH AFTER SUNRISE AS DAYTIME
HEATING MIXES DRIER AIR TO THE SURFACE. WITH HIGH PRESSURE IN
CONTROL...EXPECT LIGHT WINDS AND MOSTLY SUNNY SKIES TODAY. SOME
CLOUD COVER WILL MOVE IN LATE TONIGHT AS A WEAK FRONT APPROACHES
FROM THE WEST.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
A WEAK FRONT WILL MOVE ACROSS THE REGION FRIDAY. STILL APPEARS THAT
THE PRIMARY IMPACTS WILL BE INCREASED CLOUD COVER AND A WIND SHIFT.
MODELS INDICATE THAT AN ISOLATED SHOWER COULD OCCUR NORTH OF
INTERSTATE 80...BUT MODELS HAVE BEEN CONSISTENT OVER THE LAST FEW
DAYS SHOWING NO THREAT OF PRECIP SOUTH OF THE INTERSTATE.
THE INFLUENCE OF HIGH PRESSURE WILL RETURN FRIDAY NIGHT...
CLEARING SKIES OUT. SOUTHERLY WINDS ON SATURDAY WILL PROMOTE A
SLIGHT WARMUP AND BRING HIGHS A FEW DEGREES ABOVE NORMAL.
CLOUDS WILL INCREASE ONCE AGAIN SATURDAY NIGHT AS A MORE POTENT
FRONT MOVES ACROSS THE PLAINS. WILL INCREASE POPS TO HIGH CHANCE
ACROSS OHIO BY SUNDAY AFTERNOON.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
NEXT SYSTEM PROGGED TO APPROACH THE REGION LATE SUNDAY. CURRENTLY
MODELS INDICATE A SERIES OF SHORTWAVES DEEPENING THE POSITIVELY
TILTED UPPER LEVEL TROUGH AND ALLOWING FOR VERY COLD H850
TEMPERATURES OVER CANADA TO SINK SOUTHWARD TO AS FAR AS
MISSISSIPPI VALLEY BY TUESDAY.
HAVE BUMPED POPS UP TO LIKELY FOR SUNDAY NIGHT INTO MONDAY WITH
GOOD CONSENSUS BETWEEN 01/00Z GFS/ECMWF/NAEFS...AND WILL CONTINUE
CHANCE POPS FOR MONDAY NIGHT INTO TUESDAY.
WITH THE H850 TEMPERATURES REACHING -12C AND NORTHWEST
FLOW...HIGH TEMPERATURES COULD BE 10 DEGREES BELOW NORMAL TUESDAY
AND WEDNESDAY.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
RECENT SURFACE AND IR SATELLITE DATA CONTINUE TO SHOW PATCHES OF
MVFR STRATUS ACROSS EASTERN OHIO, SOUTHWESTERN PENNSYLVANIA, AND
ACROSS THE APPALACHIAN MOUNTAINS. THE STRATUS FORMED OVERNIGHT DUE
TO NOCTURNAL COOLING OF MOISTURE TRAPPED BENEATH A STRENGTHENING
SUBSIDENCE INVERSION. THE CLOUDS HAVE BEEN MOVING TOWARD THE
NORTHEAST. HOWEVER, EXPECT ALL THE STRATUS TO DISSIPATE BY 15Z
AS SUPPORTED BY RECENT HRRR MODEL OUTPUT. EXPECT VFR CLEAR TO
CONTINUE THROUGH TONIGHT.
OUTLOOK...FRIDAY THROUGH MONDAY...
PREVALENT VFR THROUGH SATURDAY, EXCEPT NEAR I-80 LATE FRIDAY DUE TO
POSSIBLE RESTRICTIONS WITH SCATTERED COLD FRONTAL SHOWERS. MORE
WIDESPREAD RESTRICTIONS STARTING LATE SUNDAY WITH INCOMING MIDWEST
COLD FRONTAL BAND OF SHOWERS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
627 AM EST THU DEC 1 2011
UPDATED AVIATION DISCUSSION FOR 12Z TAFS
.SYNOPSIS...
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WNW FLOW OVER THE
UPR GRT LKS BTWN TROFFING CENTERED OVER HUDSON BAY AND UPR RDG IN
THE SRN PLAINS. POSITIVELY TILTED SHRTWV IN THE NRN PLAINS MOVING
THRU THIS FLOW AND ASSOCIATED SFC LO PRES/COLD FNT STRETCHING FM
NCNTRL WI SWWD INTO THE CENTRAL PLAINS AT 04Z IS BRINGING AN AREA OF
SN TO THE UPR GRT LKS. MAIN FORCING MECHANISMS APPEAR TO BE UPR DVGC
IN EXIT REGION OF SUPPORTING 100KT H3 JET MAX AND BAND OF H85-7 FGEN
ASSOCIATED WITH FRONTAL ZN...BUT DRYNESS OF LLVLS PER NEARBY 00Z
RAOBS/LACK OF SGNFT ISENTROPIC ASCENT/MODEST DEEP LYR QVECTOR CNVGC
IS GENERALLY LIMITING THE OVERALL SN INTENSITY. TO THE NW...
SPRAWLING SFC HI PRES CENTERED JUST W OF LK WINNIPEG IS PUSHING
COLDER AND EVEN DRIER LLVL AIR SWD...WITH H85 DWPT DOWN TO -21C/-27C
AT INL/YPL AT 00Z. H85 TEMPS WERE -6C AT INL BUT -18C AT THE PAS
MANITOBA JUST NW OF LK WINNIPEG. THE ARRIVAL OF THIS DRIER AIR IS
TENDING TO END THE PCPN OVER NRN MN EARLY THIS MRNG.
&&
.DISCUSSION...
MAIN FCST CONCERNS IN THE SHORT TERM ARE SN TRENDS/AMOUNTS AND
POTENTIAL FOR LES INTO TNGT. FOCUS IN THE LONGER TERM SHIFTS TO
POTENTIAL FOR MORE SN THIS COMING WEEKEND.
TDAY...EXPECT PERIODS OF -SN TO BE ONGOING AT FCST ISSUANCE MAINLY
OVER THE SE HALF OF THE CWA NEAR AXIS OF H85-7 FGEN AND BAND OF HIER
H85 DWPT CLOSER TO THE H85 FNT. ALTHOUGH THE ARRIVAL OF COLDER AIR
FM THE N...WITH H85 TEMPS FALLING TOWARD -9C AT 12Z OVER THE
KEWEENAW...WL BE SUFFICIENT TO GENERATE SOME LES...FAIRLY PROFOUND
DRYING IN THE H925-85 LYR AND GENERAL ACYC NATURE OF LLVL FLOW WL
TEND TO LIMIT THE DURATION AND INTENSITY OF THE SHSN. BEST CHC FOR
HIER LES ACCUMS LOOKS TO BE IN AN AREA FM MQT-MUNISING FAVORED BY
EXPECTED N WIND AND WHERE DEEPER MSTR IS PROGGED TO LINGER UNTIL
ABOUT NOON. LINGERING LES SHOULD DIMINISH FAIRLY STEADILY THIS AFTN
EVEN THOUGH QUITE A BIT OF SC SHOULD PERSIST WITH MOISTENING OFF LK
SUP. OTRW...EXPECT STEADY OR SLOWLY FALLING TEMPS THRU THE DAY WITH
THESE CLDS AND FALLING H85 TEMPS TO ARND -13C OVER THE NW LATER.
TNGT...WITH ARRIVAL OF SFC RDG AXIS/MORE ACYC BACKING FLOW...EXPECT
SKIES TO CLR OVER MOST OF THE CWA. THE LK CLDS WL BE MORE RESILIENT
OVER THE KEWEENAW AND E OF MUNISING IN AREAS EXPERIENCING OVERWATER
FETCH. ALSO KEPT LINGERING POPS FOR LES IN THESE AREAS...ESPECIALLY
OVER THE E WITH LONGER FETCH/MOISTENING TO OVERCOME DRY LLVLS. BUT
GENERAL DRYNESS/LARGER SCALE ACYC FLOW AS WELL AS GENERALLY POOR SN
GROWTH PARAMETER WITH DGZ ABV THE RELATIVELY SHALLOW MIXED LYR SUG
SN ACCUMS WL BE ON THE LGT SIDE. EXPECT THE LOWEST MIN TEMPS OVER
THE INTERIOR W HALF...WHERE THE LK MODERATION WL BE LEAST.
FRI...AS THE SFC HI PRES RDG SHIFTS TO THE E AND THE FLOW BACKS
SW... ANY LINGERING LES WL END IN THE MRNG AND GIVE WAY TO A GOOD
AMOUNT OF AFTN SUNSHINE. EVEN WITH THE GREATER INSOLATION...STABLE
NATURE OF FCST SDNGS WITHIN LLVL COLD AIR IN THE ARCTIC AIRMASS
INDICATES TEMPS WL NOT RISE ABV 32 AT MOST PLACES.
FRI NGT...STRONG SW FLOW BTWN HI PRES MOVING TOWARD NEW ENGLAND AND
APRCHG COLD FNT ATTENDANT TO SHRTWV/SFC LO TRACKING INTO HUDSON BAY
IS FCST TO DRAW MORE SGNFT MSTR TO THE N...WITH PWAT 150 TO 200 PCT
OF NORMAL BY 12Z. CONSIDERING THE STRONG SW FLOW /NAM SHOWS H85
WINDS UP TO 50 KTS/ AND MSTR RETURN...EXPECT MIN TEMPS TO BE HIER
THAN TNGT.
THIS WEEKEND...THE 00Z GFS/ECMWF AND 21Z SREF ARE IN GOOD AGREEMENT
ON INTERACTION BTWN ARCTIC BRANCH TROF IN CENTRAL CANADA AND
DISTURBANCE/MSTR WITHIN SRN BRANCH SW FLOW IN THE CONUS ON NW FLANK
OF UPR RDG OFF THE SE COAST. SO USED A BLEND OF THIS GUIDANCE TO
POPULATE GRIDS. THESE MODELS SHOW A LO PRES WAVE DVLPG ON FNT
PUSHING ACRS THE CWA SAT NGT...WITH CENTER OF LO PRES MOVING ACRS
NRN LK MI AND INTO SE ONTARIO ON SUN. TENDED TOWARD THE HIER LIKELY
POPS OVER THE SE HALF OF THE CWA...WHERE THE MODELS INDICATE AS MUCH
AS 3 TO 6 INCHES OF SN MAY ACCUMULATE ON SAT/SAT NGT UNDER UPR DVGC/
H85-7 FGEN IN RRQ OF JET MAX OVER ONTARIO IN CONFLUENCE ZN BTWN THE
2 BRANCES ON THE COLD SIDE OF SFC FRONTAL BNDRY...EVEN IF SOME RA
MIXES WITH THE PCPN NEAR LK MI. TENDED TO MAINTAIN HIER POPS ON SUN
OVER THE NCNTRL THAN INDICATED BY ALL BLEND GUIDANCE CONSIDERING THE
POTENTIAL FOR LINGERING LK ENHANCEMENT WITH SHARPER CYC NNW FLOW
SHOWN BY THE MOST CONSISTENT 00Z ECMWF.
&&
.AVIATION /FOR 12Z TAF ISSUANCE/
EXPECT CLEARING CONDITIONS THROUGH THE TAF PERIOD AS DRY HIGH
PRESSURE WORKS INTO THE AREA FROM THE WEST. UNCERTAINTY REMAINS AS
TO EXACTLY WHEN LOW CLOUDS AND SNOW WILL END AT EACH OF THE
SITES...SO SOME ADJUSTMENTS OF THE END TIMES IN THE TAFS WILL LIKELY
BE NEEDED. HOWEVER...CONFIDENCE IS HIGH THAT ALL SITES WILL BE AT
LEAST MID AFTERNOON AT IWD AND CMX...AND BY THIS EVENING AT SAW.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
AN ELONGATED LOW PRESSURE TROUGH FROM THE CENTRAL PLAINS TO FAR
EASTERN LAKE SUPERIOR WILL MOVE EAST TODAY. IN ITS WAKE...HIGH
PRESSURE OVER THE NORTHERN PLAINS WILL EXTEND A RIDGE OVER LAKE
SUPERIOR THROUGH FRIDAY MORNING...SINKING SOUTHEASTWARD TO THE
CENTRAL PLAINS. ON FRIDAY THE HIGH WILL MAKE ITS WAY TO THE
NORTHEASTERN STATES. MEANWHILE...LOW PRESSURE SYSTEM OVER HUDSON BAY
WILL DRAG A TROUGH ACROSS LAKE SUPERIOR SATURDAY AFTERNOON THROUGH
SATURDAY NIGHT. AHEAD OF THE TROUGH...EXPECT SOME SOUTHWEST GALE
FORCE GUSTS TO 35 KNOTS FRIDAY AFTERNOON INTO EARLY SATURDAY. HELD
OFF ON ISSUING ANY GALE HEADLINES SINCE GUSTS WILL ONLY MARGINALLY
MEET GALE CRITERIA. A LOW PRESSURE SYSTEM WILL TAKE SHAPE OVER THE
PLAINS SATURDAY NIGHT AND MERGE WITH THE TROUGH ON SUNDAY MORNING AS
IT REACHES LAKE MICHIGAN. THIS LOW WILL MOVE JUST EAST OF LAKE
SUPERIOR ON SUNDAY AFTERNOON AND REACH QUEBEC BY SUNDAY NIGHT.
ANOTHER LOW WILL DROP FROM ALBERTA INTO MINNESOTA SUNDAY
NIGHT...BEFORE MERGING WITH THE LINGERING TROUGH EAST OF LAKE
SUPERIOR BY MONDAY EVENING. THERE IS INCREASED UNCERTAINTY WITH
RESPECT TO WIND DIRECTIONS AND SPEEDS...AND THEREFOR WAVE HEIGHTS
STARTING SUNDAY EVENING. THE UNCERTAINTY IS DUE TO VARIABILITY
BETWEEN FORECAST MODELS ON THE TRACK AND STRENGTH OF THE LOW
PRESSURE SYSTEM COMING IN FROM THE WEST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...KC
DISCUSSION...KC
AVIATION...TITUS
MARINE...TITUS
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
916 AM CST THU DEC 1 2011
.AVIATION...
15Z UPDATE/CONCERNS...
STRONG WARM ADVECTION ON 30KT+ WINDS IN THE 1.5-3 KFT LAYER IS
INDUCING RAPID MVFR STRATUS GROWTH ALONG/WEST OF I-35 CORRIDOR.
CIGS INITIALLY WILL BE EITHER OF 2 KFT. RUC SOUNDINGS SHOW THAT
WARMING TODAY WILL RESULT IN CIGS RAPIDLY RISING TO VFR UNDER 4
KFT BY 17Z...THEN QUICKLY RISING ABOVE 4 KFT BY 18Z AND AFTER.
OTHERWISE...COLD FRONT WILL REMAIN WELL NORTHWEST OF NORTH TX
TERMINALS TODAY. SOUTHEAST WINDS AROUND 10 MPH WILL BACK TO THE
EAST AT/BELOW 10 KTS BY 00Z FRIDAY.
05/
&&
.PREV DISCUSSION... /ISSUED 346 AM CST THU DEC 1 2011/
NO MAJOR CHANGES TO THIS PACKAGE. RAIN IS STILL EXPECTED TO BEGIN
IN WESTERN COUNTIES ON FRIDAY...WITH RAIN LIKELY OVER ALMOST ALL
OF NORTH TEXAS BEGINNING SATURDAY MORNING AND SPREADING EAST
THROUGH SUNDAY MORNING. PRECIP SHOULD SHUT OFF BY SUNDAY NIGHT IN
ALL BUT SOUTHEASTERN COUNTIES WHERE SOME OVER RUNNING PRECIP IS
INDICATED FOR MONDAY. HAVE REMOVED MENTION OF THUNDER IN SOUTHERN
COUNTIES DUE TO VERY MARGINAL CAPE VALUES. THERE MAY BE A
LIGHTNING STRIKE OR TWO SOMEWHERE IN THE SOUTH...BUT REAL
INSTABILITY APPEARS TO REMAIN SOUTH OF THE NORTH TEXAS CWA.
COLD FRONT REACHES NORTHWEST COUNTIES SATURDAY NIGHT AND PUSHES
SOUTHEAST OF SOUTHERN COUNTIES SUNDAY MORNING. AT THIS
TIME...TEMPERATURES APPEAR WARM ENOUGH THAT NO WINTER PRECIP IS
EXPECTED IN NORTH TEXAS. SHOULD THE COLD FRONT ARRIVE EARLIER AND
STRONGER...NORTHWEST COUNTIES MAY SEE SOME FREEZING RAIN SUNDAY
MORNING. WILL CONTINUE TO MONITOR MODEL TRENDS ON
TEMPERATURES/FROPA TIMING.
REST OF THE WEEK LOOKS COOL AND DRY. WITH LIGHT WINDS...CLEAR
SKIES...AND COOL DRY AIR MASS...WEDNESDAY MORNING LIKELY TO BE
BELOW FREEZING OVER THE ENTIRE NORTH TEXAS AREA. ECMWF/GFS PROG
MOISTURE RETURN ON DAY 8 FRIDAY...BEYOND SCOPE OF THIS FORECAST.
84
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 64 50 60 54 65 / 5 10 40 40 70
WACO, TX 67 53 64 56 68 / 5 10 40 40 60
PARIS, TX 62 45 59 46 62 / 5 10 20 30 70
DENTON, TX 63 46 57 54 64 / 5 10 40 50 70
MCKINNEY, TX 63 46 58 51 64 / 5 10 30 40 70
DALLAS, TX 64 51 61 53 65 / 5 10 30 40 70
TERRELL, TX 64 47 61 51 64 / 5 10 30 30 60
CORSICANA, TX 67 50 66 54 68 / 5 10 30 30 60
TEMPLE, TX 67 53 64 56 68 / 5 10 40 50 60
MINERAL WELLS, TX 61 46 56 56 63 / 10 40 50 60 70
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
05/84
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
331 PM MST THU DEC 1 2011
.SHORT TERM /TONIGHT THROUGH SATURDAY/...
LATE THIS AFTERNOON/EVENING...SNOW AND WIND WINDING DOWN ACROSS THE
NORTH AS FOCUS FOR WEATHER SHIFTS TO THE SOUTH.
THE CLOSED LOW WAS STILL NEAR THE CA/AZ BORDER PER WATER VAPOR
SATELLITE IMAGE. CLOUD TOPS COOLING OVER SW CO/SE UT THIS AFTERNOON
AHEAD OF A VORTICITY MAX SHOWN IN THE RUC MODEL TO BE OVER NORTHEAST
NM. THIS HAS PRODUCED A COUPLE INCHES OF NEW SNOW SOUTH OF SILVERTON
PER A REPORT FROM THE COLORADO AVALANCHE CENTER. CALL TO A SPOTTER IN
PARADOX...WHERE RADAR ECHOES HAVE BEEN STRONGEST...REVEALED JUST
CLOUDY SKIES TO LIKELY AT LEAST SOME LIGHT SNOW OVER THE HIGHER
PEAKS OF THE LA SALS AND UNCOMPAHGRE PLATEAU. THIS DISTURBANCE
EXPECTED TO MOVE INTO SW CO LATE TODAY BEFORE PEELING OFF TO THE
NORTHEAST. WILL KEEP SCATTERED SHOW SHOWERS OVER THE SAN JUANS MTNS.
MORE NUMEROUS SHOWERS IN SE UT CLOSER TO A SECOND AND STRONGER
DISTURBANCE ROTATING AROUND THE CLOSED LOW. CLEARING SKIES ACROSS THE
NORTH TONIGHT.
THE SOUTHWEST CLOSED LOW IS EXPECTED TO REMAIN OVER SWRN AZ TONIGHT
BEFORE OPENING UP AND SLOWLY MOVING EAST FRI-FRI NIGHT AS ANOTHER
SPLITTING TROUGH DROPS SOUTH INTO THE GREAT BASIN. THIS EVENTUALLY
EXPECTED TO BRING ANOTHER COLD FRONT DOWN INTO THE FORECAST AREA FRI
NIGHT...AS ANOTHER CLOSED UPPER LOW DEVELOPS OVER AZ BY SAT. SIMILAR
SCENARIO TO THE CURRENT ONE EXCEPT ABSENT THE EXTREME NE WINDS THAT
WERE OBSERVED EARLY THIS MORNING.
SE TO S WINDS 20-30 KTS AT 700 MB WILL BE BRING SEVERAL INCHES OF
SNOW O THE SOUTHERN MTNS FRIDAY BEFORE RELAXING FRI NIGHT AS THE
SOUTHERLY OROGRAPHIC WINDS SUBSIDE. SNOW CHANCES INCREASE ACROSS THE
N FRI NIGHT AS THE SFC FRONT AND DEFORMATION ZONE ALOFT DROP IN FROM
THE NORTH...WITH SNOW FOCUS SHIFTING TO THE SOUTH SAT AFTERNOON AS
THE CLOSED LOW FULLY DEVELOPS OVER AZ. BUT...CONFIDENCE NOT THE
GREATEST GIVEN THE RATHER COMPLEX INTERACTION BETWEEN THE EXITING
FIRST CLOSED LOW AND THE SECOND TROUGH/LOW DROPPING SOUTH. ONE AREA
TO KEEP AN EYE ON IS THE SOUTHERN FOOTHILLS OF THE SAN JUAN MTNS IN
THE SOUTHERLY UPSLOPE FLOW.
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
INITIALLY THE MED RANGE MDLS START OUT IN GOOD AGREEMENT WITH UPPER
LOW OVER AZ MOVING EASTWARD TOWARD NM SATURDAY NIGHT. EC A BIT SLOWER
WITH THIS EASTWARD MOVEMENT BUT EITHER WAY ANY PCPN APPEARS TO BE
FOCUSED OVER THE SAN JUANS WHERE MOISTURE AND FORCING APPEAR BEST.
WILL RAISE POPS TO THE LIKELY CATEGORY THERE BUT LIMIT SNOWFALL TO
AROUND AN INCH OR LESS. OROGRAPHIC COMPONENT GENERALLY LACKING WITH
H7 WINDS GENERALLY 10KTS OR LESS. THE NEXT SIGNIFICANT SHRT WV IN
A HIGH AMPLITUDE NORTHERLY FLOW WILL DROP OUT OF CANADA SUNDAY AND
APPROACH OUR CWA FROM THE NORTHEAST. AT THE SAME TIME SOUTHERN TROF
WILL STILL BE MOVING TOWARD NM. THE SLOWER EC HANGS ON TO A FEW
SHWRS OVER THE SRN MTNS...WHILE THE GFS BEGINS TO SPREAD PCPN ACROSS
THE NRN PART OF THE CWA IN RESPONSE TO APPROACHING STRONG COLD
FRONT. WILL COMPROMISE FOR NOW WITH SCATTERED POPS MOST MTN
LOCATIONS. STRONG COOLING ALOFT IS NOTED IN THE GFS WHICH PUSHES
THE COLD FRONT THROUGH THE ENTIRE CWA BY EARLY MONDAY MORNING. BY
EARLY MONDAY MORNING COLD CORE WILL BE OVER WRN CO WITH THE COLDEST
TEMPS OF THE SEASON SO FAR (H5 TEMP -33C).
THE COLD UPPER TROF WILL BEGIN TO SHIFT EASTWARD MONDAY WHILE RIDGE
TRIES TO BUILD OVER THE GRT BASIN. THE NEXT ARCTIC SHRT WV WILL
FLATTEN THE FLOW TUE/WED BEFORE DROPPING SOUTHWARD INTO THE GRT BASIN
THURSDAY WHICH PROMISES ANOTHER SHOT OF WINTRY WX AND COLD
TEMPERATURES.
&&
.AVIATION /FOR 00Z TAF ISSUANCE/...
MOSTLY VFR CONDITIONS ARE EXPECTED THIS EVENING AT ALL THE TAF
SITES...LASTING THROUGH FRIDAY MORNING. HOWEVER PILOTS FLYING IN
SOUTHWESTERN COLORADO AND SOUTHEAST UTAH WILL EXPERIENCE MTN OBSC
AND MVFR VSBY IN LIGHT SNOW.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...JAD
LONG TERM....MC
AVIATION.....TGJT
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
406 PM EST THU DEC 1 2011
.SYNOPSIS...
HIGH PRESSURE BUILDS INTO THE MID ATLANTIC REGION FROM THE WEST
TONIGHT THROUGH WEEKEND. A WEAK...DRY COLD FRONT WILL CROSS INTO
THE AREA FRIDAY NIGHT...BRINGING SLIGHTLY COOLER TEMPERATURES
SATURDAY. MILDER CONDITIONS RETURN FOR THE LATTER HALF OF THE
WEEKEND INTO EARLY NEXT WEEK AHEAD OF A SLOW MOVING COLD
FRONT...WHICH APPROACHES THE REGION FROM THE WEST BY THE MIDDLE OF
NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST WX ANALYSIS DEPICTS ~1028MB SURFACE HIGH PRESSURE OVER
E KY/TN. ALOFT...TROUGH-RIDGE-TROUGH PATTERN EVIDENT ON RUC H5
ANALYSIS AS MID LEVEL TROUGHING HAS NOW TRANSITIONED OFF THE EAST
COAST...WITH LOW AMPLITUDE H5 RIDGING TO THE WEST OVER THE GULF
COAST/LOWER MS VALLEY...WITH CLOSED OFF/POSITIVELY TILTED UPPER
LEVEL LOW PRESSURE REMAINS IN PLACE OVER BAJA/SOUTHERN
CALIFORNIA.
BREEZY CONDITIONS STILL IN PLACE OVER MAINLY COASTAL ZONES THIS
AFTERNOON AS A RESULT OF PRESSURE GRADIENT BETWEEN DEPARTING MID
LEVEL TROUGH...AND HIGH PRESSURE TO THE WEST. COASTAL AREAS
SHOULD CONTINUE TO BE BREEZY (GUSTS TO 15-17 KT) FOR A FEW MORE
HOURS BEFORE DECOUPLING/RELAXING PRESSURE GRADIENT ALLOWS FOR
WINDS TO DROP OFF EARLY THIS EVENING. OTHERWISE...A MOSTLY CLEAR
AND PLEASANT LATE FALL AFTERNOON ACROSS THE CWA...MAXIMA WL AVERAGE
OUT INTO THE MID 50S INLAND...LOW TO MID 50S OVER COASTAL ZONES.
CLEAR SKIES/LIGHT WINDS PORTEND TO GOOD RADIATING CONDITIONS
TONIGHT. LOOKING FOR TEMPERATURES BE CLOSE TO/JUST BELOW LAST
NIGHTS/THIS MORNING`S LOWS. LOOK FOR LOWS INTO THE M-U 20S
INLAND...LOW TO MID 30S OVER COASTAL ZONES.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
LATE WEEK/WEEKEND TIME FRAME CHARACTERIZED BY SLOWLY BUILDING UPPER
LEVEL RIDGING WITH TIME OVER THE EASTERN CONUS...RESULTING IN
CONTINUED DRY WEATHER THROUGH THE PERIOD.
FRIDAY...
HIGH PRESSURE BECOMES ENTRENCHED OVER THE MID ATLANTIC
STATES THROUGH THE WEEKEND. AS A CUTOFF LOW DEVELOPS OVER THE
SOUTHWESTERN US...A WEAK UPPER LEVEL TROUGH WILL BECOME SEPARATED
FROM IT AND DRIFT ACROSS THE NORTHERN PLAINS/UPPER GREAT
LAKES...BEFORE SLOWLY PUSHING ACROSS NEW ENGLAND BY FRIDAY NIGHT.
THIS FEATURE WILL EVENTUALLY PUSH WEAK/DRY FRONTAL BOUNDARY TO OUR
NORTH THROUGH THE REGION LATE TOMORROW INTO SATURDAY WITH LITTLE
MORE THAN A FEW MID-HIGH CLOUDS PUSHING ACROSS THE AREA. MAXIMA
SLIGHTLY WARMER THAN TODAY`S VALUES...GENERALLY INTO THE M/U 50S
AREA WIDE...NEAR 60 WELL INLAND. SO WHILE WE CAN EXPECT A SLIGHTLY
MILDER EVENING FRIDAY NIGHT...HAVE SIDED CLOSER TO COOLER ENVELOPE
OF MAV GUIDANCE IN EXPECTATION OF LIGHT WINDS OVER LAND AND STILL
RELATIVELY SCANT MID LEVEL CLOUD COVER AS HIGH PRESSURE SLIDES
OVERHEAD. EARLY MORNING LOWS FRI NIGHT/SAT MORNING GENERALLY INTO
THE L-M30S TO NEAR 40 ALONG COASTAL ZONES.
SATURDAY...
THE SURFACE HIGH BECOMES POSITIVELY TILTED ON SATURDAY AS THE
RIDGE AXIS BEGINS TO SHIFT OFFSHORE. DESPITE AFOREMENTIONED
WARMING WITH TIME ALOFT AS SUBTROPICAL RIDGE BEGINS TO BUILD ACROSS
THE SOUTHEASTERN CONUS...TEMPERATURES WILL BE MODESTLY COOLER
SATURDAY DUE TO THE INFLUENCE OF MODIFYING ~1036MB SFC HIGH
PRESSURE PUSHING IN FROM THE WEST. AS WE`VE SEEN SEVERAL TIMES
ALREADY THIS FALL...LIMITED MIXING NOTED ON FORECAST SOUNDINGS FOR
SATURDAY (GENERALLY TO ~950-925MB) WILL KEEP TEMPERATURES A BIT
LOWER THAN LOCAL THICKNESS TOOLS AND WARMER MAV GUIDANCE DEPICT.
AS SUCH...HAVE GONE CLOSER TO COOLER MET VALUES FOR MAXIMA ON
SATURDAY WHICH YIELD SEASONABLE...ALBEIT SLIGHTLY COOLER...MAXIMA
INTO THE LOW TO MID 50S.
SATURDAY NIGHT/SUNDAY...
SURFACE HIGH PIVOTS TO THE MID-ATLANTIC/SE COAST AND THEN
OFFSHORE SAT NIGHT THROUGH SUNDAY...WITH DEVELOPING RETURN (SOUTH-
SOUTHEAST) FLOW AND CONTINUED BUILDING OF RIDGING ALOFT INITIATING
MODERATING TEMPERATURE TREND FOR SATURDAY NIGHT THROUGH THE EARLY
PORTION OF NEXT WEEK. LOOK FOR EARLY MORNING LOWS CONTINUED DRY
AND MILDER CONDITIONS SUNDAY WITH MAXIMA INTO THE L-M 60S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
OVERALL PATTERN IN THE EXTENDED FAVORS A DOMINANT MID/UPPER LEVEL
RIDGE CENTERED FROM THE GULF OF MEXICO ENE ACRS FLORIDA AND TOWARDS
BERMUDA. MEANWHILE...A DEEP TROUGH OVER CENTRAL CANADA WILL
GRADUALLY PUSH SOUTH AND TAKE ON A POSITIVE TILT (OR EVEN BECOME
CUTOFF) OVER THE CENTRAL CONUS. THIS SETUP WILL BE VERY SLOW TO
CHANGE THROUGH THE MIDDLE OF NEXT WEEK...AND WILL KEEP BULK OF
PRECIPITATION OFF TO OUR WEST UNTIL WED. FOR THE MID ATLC AND SE
STATES...THIS WILL ALSO TRANSLATE INTO WELL ABOVE AVG TEMPERATURES
MON-TUE...AND POSSIBLY WED BEFORE COOLING DOWN TO AROUND AVG ON THU.
GIVEN THE CONTINUED MODEL DISCREPANCIES (LATEST ECMWF REMAINING
ABOUT 12-18 HRS SLOWER THAN THE GFS/GLOBAL GEM
ENSEMBLES....CONFIDENCE IN TUE-THU FCST IS LOWER THAN AVG.
AS WITH PREVIOUS FCST...HAVE GENLY BROAD-BRUSHED A LOW CHANCE POP
ACRS THE NW ZONES...TO DRY OR SLIGHT CHANCE ELSEWHERE FROM LATE MON
THROUGH TUE. WILL FOCUS HIGHEST POPS DURING THE DAY WED/WED EVENING
AS A BLEND OF MODEL TIMING PUSHES THE SFC COLD FRONT THROUGH.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
HIGH PRES CENTERED OVER THE OH VALLEY WILL KEEP SKIES CLEAR
THROUGH THE TAF PERIOD AND INTO LATE FRI. A MOSTLY DRY COLD FRONT
WILL APPROACH LATE FRI INTO SAT. VFR CONDITIONS ARE EXPECTED
THROUGH THE WEEKEND.
&&
.MARINE...
SCA HEADLINES ARE IN THE PROCESS OF BEING TRIMMED BACK W/ AFTN
PACKAGE...GENLY KEEPING SCA HEADLINES IN EFFECT OVER SOUTHERN AREAS
INTO THE EVENING...WHILE WINDS ARE A BIT LIGHTER TO THE NORTH WHERE
THE HEADLINES ARE ENDING. FOR SOUTHERN COASTAL WATERS THE SCA
HEADLINES MAY NEED TO BE EXTENDED BEYOND THE EVENING IF SEAS ARE
SLOWER TO DROP THAN FCST.
QUIET CONDITIONS FRI...FOLLOWED BY ANOTHER BOUNDARY/COOL SURGE FRI
NIGHT...WITH MARGINAL SCA EVENT LIKELY ONCE AGAIN OVER THE
BAY....AND POSSIBLE ON THE COASTAL WATERS. AS THIS IS LATER 3RD
PERIOD...HAVE DECIDED TO WAIT UNTIL CURRENT HEADLINES END BEFORE
RAISING ANOTHER SET (ALTHOUGH FCST DOES INCLUDE SCA CONDITIONS).
THIS SURGE IS FAIRLY BRIEF...AND SHOULD END BY LATE SAT MORNING
ASIDE FROM LINGERING 5 FT SEAS OVER SOUTHERN COASTAL WATERS.
OTHERWISE...BENIGN SAT EVENING THROUGH MON AS HIGH PRESSURE SETTLES
OVER THE REGION AHEAD OF THE NEXT COLD FRONT. WINDS GRADUALLY TURN
SOUTHERLY SUN-TUE BUT WIND SPEEDS LOOK TO AVG 10-15 KT OR LESS.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR
ANZ633. SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
ANZ656- 658.
&&
$$
SYNOPSIS...MAM
NEAR TERM...MAM
SHORT TERM...MAM/BMD
LONG TERM...LKB
AVIATION...JEF
MARINE...LKB
AREA FORECAST DISCUSSION
NWS GAYLORD MI
347 PM EST THU DEC 1 2011
.SYNOPSIS.../ISSUED AT 346 PM/
THE LESS THAN IMPRESSIVE COLD FRONT THAT BROUGHT THE CLOUDS AND
PRECIPITATION TODAY...WILL SLIDE SOUTHEASTERLY TONIGHT. THIS WILL
OPEN A SHORT WINDOW OF OPPORTUNITY TONIGHT FOR SOME LAKE EFFECT
FLURRIES INTO THE EARLY MORNING HOURS OF FRIDAY...BUT ANY LINGERING
PRECIPITATION WILL BE GONE BY MID DAY. THAT WILL LEAVE SETTLED
CONDITIONS IN PLACE FOR THE BALANCE OF FRIDAY. HOWEVER...THE QUIET
WEATHER WILL BE SHORT LIVED AS THE NEXT DISTURBANCE MOVES IN ON
SATURDAY AND WILL KEEP RAIN AND SNOW PROBABLE THROUGH THE WEEKEND.
BERGER
&&
.SHORT TERM.../ISSUED AT 346 PM/...TONIGHT
MAIN FCST CHALLENGE HEADING INTO THE NIGHT REVOLVES AROUND LINGERING
LIGHT PRECIP CHANCES ACROSS SOUTHERN COUNTIES...AND POTENTIAL FOR
SOME WEAK LAKE EFFECT OVERNIGHT. EARLY AFTN ANALYSIS PLACES A COLD
FRONT AT THE SURFACE DRAPED ACRS NORTHWEST LOWER...TIED TO WEAK
SURFACE LOW CROSSING MANITOULIN ISLAND AS OF 19Z. REGIONAL RADAR
MOSAIC CONTINUES TO SHOW AN ELONGATED AXIS OF MAINLY LIGHT PRECIP
BISECTING MAINLY NORTHERN LOWER...DRIVEN BY COMBO OF FAIRLY DEEP
FRONTOGENETICAL FORCING AND UPPER JET DIVERGENCE IMMEDIATELY IN THE
WAKE OF THE SURFACE BOUNDARY. PRECIP TYPE THUS FAR THIS AFTN HAS
BEEN MAINLY LIQUID OUTSIDE OF THE HIGHER TERRAIN...THANKS TO
GENEROUSLY WARM BOUNDARY LAYER...WITH SFC-BASED MELTING LAYERS
PUSHING 1.5KFT PER LATEST RUC FCST RAOBS. LATEST RADAR IMAGES HAVE
SHOWN SOME INTENSIFICATION OF THE PRECIP RETURNS...LIKELY THE
CONSEQUENCE OF STRENGTHENING FGEN AS COLD ADVECTION INCREASES...AND
SOME UPTICK IN MID LEVEL QG UPWARD FORCING WITH APPROACH OF
SHARPENING UPPER TROUGH FROM THE UPPER MIDWEST.
FORESEE THIS BAND OF FGEN-DRIVEN PRECIP GRADUALLY PROGRESSING
SOUTHWARD INTO THE AFTN AND EVENING HOURS...AND WILL RATHER RAPIDLY
FLIP THE PRECIP TYPE OVER TO ALL SNOW AS THE SUN SETS AND SHALLOW
MELTING LAYER IS ERASED VIA QUICK PUSH OF STRONGER COLD ADVECTION.
THEREAFTER...FOCUS IS ON WHETHER LAKE EFFECT PRECIP WILL DEVELOP OR
NOT. INCOMING AIR MASS IS CERTAINLY COLD ENOUGH (900MB TEMPS RUNNING
AROUND -10C TO -13C)...BUT IS VERY DRY...WITH UPSTREAM PWATS BELOW
0.1 INCHES! (SEE SFC DEW POINTS INTO THE SINGLE DIGITS). AS
SUCH...BELIEVE THAT WE WILL LIKELY SEE SOME LIMITED LAKE
RESPONSE...BUT HAVE A HARD TIME SEEING MUCH MORE THAN JUST SOME
FLURRIES FALLING ACROSS NORTHERN LOWER...WHILE DEEPER PUSH OF COLD
ADVECTION MAY ALLOW FOR SOME SCATTERED SNOW SHOWERS INTO THE EASTERN
U.P. IN FACT...ALREADY SEEING SOME STREAMERS UP THAT WAY...SO WILL
ADD IN A SMALL POP FOR MEASURABLE SNOW. OVERNIGHT LOWS CHILLY...DOWN
INTO THE UPPER TEENS TO MIDDLE 20S.
LAWRENCE
&&
.LONG TERM.../ISSUED AT 346 PM/...FRIDAY AND BEYOND
SHORT RANGE (FRIDAY)...LOOKING LIKE A RATHER NICE EARLY DECEMBER DAY
ON TAP WITH BONE DRY AIR MASS FILTERING INTO THE REGION AS LOW
LEVEL RIDGING TRAVERSES THE SOUTHERN LAKES. COULD PERHAPS SEE SOME
LINGERING LAKE CLOUDS FOR A BRIEF TIME INTO THE MORNING...BUT
THOSE SHOULDN`T LAST WITH BACKING SOUTHWEST FLOW AND QUICK PUSH OF
WARM ADVECTION REALLY LIMITING LAKE INSTABILITY AFTER 15Z. IT WILL
STILL BE SEASONABLY CHILLY DESPITE THE EXPECTATION OF NEARLY FULL
SUNSHINE...WITH HIGHS ONLY INTO THE LOWER OR MIDDLE 30S.
LAWRENCE
OUTLOOK RANGE (FRIDAY NIGHT THROUGH THURSDAY)...LONG WAVE TROUGH
EXTENDS FROM BAFFIN ISLAND SOUTH INTO THE NATION`S HEARTLAND...WITH
BUILDING HEIGHTS OVER THE EASTERN PACIFIC. TROUGHING BECOMES MORE
AMPLIFIED OVER THE NEXT SEVERAL DAYS AS A SHORT WAVE COMING OVER THE
TOP OF THE PACIFIC RIDGE THIS AFTERNOON SPLITS INTO TWO PIECES...
WITH ONE PIECE DROPPING INTO THE SOUTHWESTERN STATES (AND KICKING
UPPER LOW CURRENTLY THERE TO THE NORTHEAST THIS WEEKEND...WHICH WILL
HAVE AN IMPACT ON GREAT LAKES WEATHER). THIS WILL ALSO SERVE TO
STRENGTHEN RIDGING OVER THE SOUTHEASTERN U.S. AND BRING HIGHER
HEIGHTS AND SOUTHWEST FLOW ALOFT INTO MICHIGAN TO END THE WEEK.
QUIETEST FORECAST PERIOD THROUGH SUNDAY WILL BE FRIDAY NIGHT AS
SHORT WAVE RIDGE AXIS CROSSES THE UPPER LAKES...CLOUDS WILL BE ON
THE INCREASE OVERNIGHT INTO SATURDAY MORNING WITHIN ISENTROPIC
ASCENT PATTERN...WITH MOIST LAYER DEEPENING DURING THE DAY AND
ALLOWING FOR WIDESPREAD MOSTLY LIGHT PRECIPITATION TO DEVELOP.
PRECIPITATION TYPE WILL MOSTLY LIKELY START OUT AS SNOW OR A MIX
(CLOSER TO LAKES MICHIGAN/HURON) ACROSS EASTERN UPPER...AND A MIX
ACROSS THE TIP OF THE MITT AND HIGHER ELEVATIONS ACROSS THE INTERIOR
(MAYBE A BRIEF EARLY FREEZING RAIN THREAT). PRECIPITATION SHOULD
TREND TOWARD ALL LIQUID DURING THE DAY WITHIN WARM ADVECTION
PATTERN.
GUIDANCE HAS BEEN PRETTY CONSISTENT WITH A SIGNAL TOWARD DRYING
THINGS OUT IN THE LOW LAYERS SATURDAY EVENING AT LEAST ACROSS
NORTHERN LOWER...WHICH WOULD CUT PRECIP OVER TO JUST SOME DRIZZLE
FOR A TIME DURING THE EVENING BEFORE DEEP (AND BETTER FROM AN
ABSOLUTE STANDPOINT) MOISTURE SURGES BACK IN OVERNIGHT AS A WEAK
SURFACE WAVE LIFTS NORTHEAST INTO ILLINOIS/WISCONSIN AND LOW LEVEL
JET FOCUSES TOWARD THE UPPER LAKES. PRECIPITATION MAY TEND TO BE
MORE PERSISTENT ACROSS THE UPPER PENINSULA SATURDAY NIGHT...AND
APPROACH OF SURFACE LOW AND FRONTAL BOUNDARY THAT EXTENDS TO ITS
NORTHEAST ALSO MEANS THAT COLDER AIR COULD BE FLIRTING WITH EASTERN
UPPER MICHIGAN OVERNIGHT. WHETHER EASTERN UPPER GOES BACK OVER TO
ALL SNOW WILL BE VERY SENSITIVE TO SURFACE LOW POSITION/TRACK...SO
NO NEED TO GET OVERLY CUTE HERE AND WILL KEEP FORECAST WORDING MORE
"MIXY" NORTH OF THE BRIDGE. THIS SAME DILEMMA CONTINUES INTO SUNDAY
AND WHETHER WE STAY ON THE WARM OR COLD SIDE OF THE SURFACE LOW
TRACK AS IT LIFTS NORTHEAST INTO LOWER MICHIGAN. IN ADDITION...
LOOKS LIKE SOME DRY SLOTTING MAY GET INVOLVED IN TERMS OF RATCHETING
DOWN PRECIP INTENSITY BY AFTERNOON. SO AGAIN...PRETTY GENERIC
FORECAST WORDING WILL HAVE TO SUFFICE.
STARTING OUT THE EXTENDED PERIODS MONDAY...SPLIT FLOW POSITIVE TILT
LONG WAVE TROUGH WILL EXTEND FROM HUDSON BAY INTO THE SOUTHWEST
U.S....WITH SOME DIFFERENCES IN THE GUIDANCE WITH RESPECT TO THE
"DEGREE" OF THIS SPLIT AND OVERALL TROUGH EVOLUTION. OPERATIONAL
GFS HAS BEEN RETICENT TO LEAVE ENERGY BEHIND OVER THE SOUTHWESTERN
U.S....WHILE THE GGEM HAS MORE "BEEF" TO ITS NORTHERN BRANCH FLOW.
WHILE THE LATTER IS A BIT OF AN OUTLIER...DON`T WANT TO TOTALLY
DISCOUNT THE GGEM AS IT MAY BE ONTO THE RIGHT OVERALL THEME. AT THE
VERY LEAST IT WILL BE TURNING COLDER FOR THE FIRST PART OF THE WEEK
AS UPPER TROUGH AXIS SWINGS THROUGH IN THE MONDAY/TUESDAY TIME FRAME
AND DRAGS A LOBE OF COLD AIR INTO THE UPPER LAKES. THE MAIN IMPACT
IF THE GGEM IDEA IS CORRECT IS A COLDER SOLUTION AND A BETTER THREAT
FOR LAKE ENHANCED SNOW LATER MONDAY AND LAKE EFFECT SNOW EVENT FOR
THE SNOWBELTS TUESDAY. WILL MAKE SOME ATTEMPT TO TREND THE FORECAST
IN THAT DIRECTION...AT LEAST WITHIN THE CONFINES OF WHAT CAN BE DONE
WITHIN THE EXTENDED FORECAST PROCESS. BEYOND THAT HOWEVER...
UNCERTAINTIES MAKE GRAPPLING WITH FORECAST DETAILS IN THE MIDWEEK
PERIOD A VERY LOW CONFIDENCE AFFAIR...INITIAL THOUGHTS ARE THAT COLD
SHOT WILL BE TRANSIENT WITH A MODERATING AIR MASS INTO WEDNESDAY/
THURSDAY. IF THIS IS THE CASE WOULD PROBABLY ALSO HAVE TO DEAL WITH
WARM ADVECTION PRECIPITATION AT SOME POINT.
JPB
&&
.MARINE.../ISSUED AT 346 PM/
SHORT RANGE (TONIGHT/FRIDAY)...BRIEF TIGHTENING OF THE PRESSURE
GRADIENT IN THE WAKE OF A DEPARTING COLD FRONT OVERNIGHT WILL
BRIEFLY KICK UP THE WINDS ON ALL NEARSHORE WATERS...WITH A FEW GUSTS
TO NEAR SMALL CRAFT ADVISORY LEVEL POSSIBLE. WINDS WILL LOWER AND
GRADUALLY BACK TO THE SOUTHWEST INTO FRIDAY...BUT REMAIN 15 KNOTS OR
LESS.
LAWRENCE
OUTLOOK (FRIDAY NIGHT AND BEYOND)...AS SURFACE HIGH PRESSURE PULLS
AWAY TO THE EAST...SOUTHERLY GRADIENT PICKS UP FRIDAY NIGHT AND
CONTINUES INTO SATURDAY. SMALL CRAFT ADVISORIES WILL LIKELY BE
REQUIRED...WITH SOME LOW END GALE FORCE GUSTS POSSIBLE IN LAKE
MICHIGAN NEARSHORE ZONES. WINDS WILL SLACKEN SATURDAY NIGHT/EARLY
SUNDAY AS LOW PRESSURE LIFTS ACROSS LOWER MICHIGAN...WITH WINDS
SWITCHING AROUND TO NORTH/NORTHWEST IN ITS WAKE LATER SUNDAY.
JPB
&&
.AVIATION.../ISSUED AT 1235 PM/...VALID FOR 18Z TAFS
A COLD FRONT WILL CONTINUE CROSSING THE TERMINAL SITES INTO THE
EVENING...BRINGING PERIODS OF MAINLY LIGHT RAIN AND
SPRINKLES...BUT PERHAPS A BRIEF PERIOD OF SOME LIGHT SNOW EARLY
THIS EVENING. MUCH COLDER AIR FILTERING INTO THE AREA LATER
TONIGHT WILL LIKELY BRING AT LEAST SOME SCATTERED LAKE EFFECT
CLOUDS...BUT VERY DRY AIR DOWN LOW SHOULD PREVENT ANYTHING IN THE
WAY OF SNOW SHOWER ACTIVITY. SKIES ARE EXPECTED TO CLEAR
COMPLETELY HEADING INTO FRIDAY MORNING WITH HIGH PRESSURE IN
CONTROL.
LAWRENCE
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1238 PM EST THU DEC 1 2011
UPDATED AVIATION DISCUSSION FOR 18Z TAFS
.SYNOPSIS...
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WNW FLOW OVER THE
UPR GRT LKS BTWN TROFFING CENTERED OVER HUDSON BAY AND UPR RDG IN
THE SRN PLAINS. POSITIVELY TILTED SHRTWV IN THE NRN PLAINS MOVING
THRU THIS FLOW AND ASSOCIATED SFC LO PRES/COLD FNT STRETCHING FM
NCNTRL WI SWWD INTO THE CENTRAL PLAINS AT 04Z IS BRINGING AN AREA OF
SN TO THE UPR GRT LKS. MAIN FORCING MECHANISMS APPEAR TO BE UPR DVGC
IN EXIT REGION OF SUPPORTING 100KT H3 JET MAX AND BAND OF H85-7 FGEN
ASSOCIATED WITH FRONTAL ZN...BUT DRYNESS OF LLVLS PER NEARBY 00Z
RAOBS/LACK OF SGNFT ISENTROPIC ASCENT/MODEST DEEP LYR QVECTOR CNVGC
IS GENERALLY LIMITING THE OVERALL SN INTENSITY. TO THE NW...
SPRAWLING SFC HI PRES CENTERED JUST W OF LK WINNIPEG IS PUSHING
COLDER AND EVEN DRIER LLVL AIR SWD...WITH H85 DWPT DOWN TO -21C/-27C
AT INL/YPL AT 00Z. H85 TEMPS WERE -6C AT INL BUT -18C AT THE PAS
MANITOBA JUST NW OF LK WINNIPEG. THE ARRIVAL OF THIS DRIER AIR IS
TENDING TO END THE PCPN OVER NRN MN EARLY THIS MRNG.
&&
.DISCUSSION...
MAIN FCST CONCERNS IN THE SHORT TERM ARE SN TRENDS/AMOUNTS AND
POTENTIAL FOR LES INTO TNGT. FOCUS IN THE LONGER TERM SHIFTS TO
POTENTIAL FOR MORE SN THIS COMING WEEKEND.
TDAY...EXPECT PERIODS OF -SN TO BE ONGOING AT FCST ISSUANCE MAINLY
OVER THE SE HALF OF THE CWA NEAR AXIS OF H85-7 FGEN AND BAND OF HIER
H85 DWPT CLOSER TO THE H85 FNT. ALTHOUGH THE ARRIVAL OF COLDER AIR
FM THE N...WITH H85 TEMPS FALLING TOWARD -9C AT 12Z OVER THE
KEWEENAW...WL BE SUFFICIENT TO GENERATE SOME LES...FAIRLY PROFOUND
DRYING IN THE H925-85 LYR AND GENERAL ACYC NATURE OF LLVL FLOW WL
TEND TO LIMIT THE DURATION AND INTENSITY OF THE SHSN. BEST CHC FOR
HIER LES ACCUMS LOOKS TO BE IN AN AREA FM MQT-MUNISING FAVORED BY
EXPECTED N WIND AND WHERE DEEPER MSTR IS PROGGED TO LINGER UNTIL
ABOUT NOON. LINGERING LES SHOULD DIMINISH FAIRLY STEADILY THIS AFTN
EVEN THOUGH QUITE A BIT OF SC SHOULD PERSIST WITH MOISTENING OFF LK
SUP. OTRW...EXPECT STEADY OR SLOWLY FALLING TEMPS THRU THE DAY WITH
THESE CLDS AND FALLING H85 TEMPS TO ARND -13C OVER THE NW LATER.
TNGT...WITH ARRIVAL OF SFC RDG AXIS/MORE ACYC BACKING FLOW...EXPECT
SKIES TO CLR OVER MOST OF THE CWA. THE LK CLDS WL BE MORE RESILIENT
OVER THE KEWEENAW AND E OF MUNISING IN AREAS EXPERIENCING OVERWATER
FETCH. ALSO KEPT LINGERING POPS FOR LES IN THESE AREAS...ESPECIALLY
OVER THE E WITH LONGER FETCH/MOISTENING TO OVERCOME DRY LLVLS. BUT
GENERAL DRYNESS/LARGER SCALE ACYC FLOW AS WELL AS GENERALLY POOR SN
GROWTH PARAMETER WITH DGZ ABV THE RELATIVELY SHALLOW MIXED LYR SUG
SN ACCUMS WL BE ON THE LGT SIDE. EXPECT THE LOWEST MIN TEMPS OVER
THE INTERIOR W HALF...WHERE THE LK MODERATION WL BE LEAST.
FRI...AS THE SFC HI PRES RDG SHIFTS TO THE E AND THE FLOW BACKS
SW... ANY LINGERING LES WL END IN THE MRNG AND GIVE WAY TO A GOOD
AMOUNT OF AFTN SUNSHINE. EVEN WITH THE GREATER INSOLATION...STABLE
NATURE OF FCST SDNGS WITHIN LLVL COLD AIR IN THE ARCTIC AIRMASS
INDICATES TEMPS WL NOT RISE ABV 32 AT MOST PLACES.
FRI NGT...STRONG SW FLOW BTWN HI PRES MOVING TOWARD NEW ENGLAND AND
APRCHG COLD FNT ATTENDANT TO SHRTWV/SFC LO TRACKING INTO HUDSON BAY
IS FCST TO DRAW MORE SGNFT MSTR TO THE N...WITH PWAT 150 TO 200 PCT
OF NORMAL BY 12Z. CONSIDERING THE STRONG SW FLOW /NAM SHOWS H85
WINDS UP TO 50 KTS/ AND MSTR RETURN...EXPECT MIN TEMPS TO BE HIER
THAN TNGT.
THIS WEEKEND...THE 00Z GFS/ECMWF AND 21Z SREF ARE IN GOOD AGREEMENT
ON INTERACTION BTWN ARCTIC BRANCH TROF IN CENTRAL CANADA AND
DISTURBANCE/MSTR WITHIN SRN BRANCH SW FLOW IN THE CONUS ON NW FLANK
OF UPR RDG OFF THE SE COAST. SO USED A BLEND OF THIS GUIDANCE TO
POPULATE GRIDS. THESE MODELS SHOW A LO PRES WAVE DVLPG ON FNT
PUSHING ACRS THE CWA SAT NGT...WITH CENTER OF LO PRES MOVING ACRS
NRN LK MI AND INTO SE ONTARIO ON SUN. TENDED TOWARD THE HIER LIKELY
POPS OVER THE SE HALF OF THE CWA...WHERE THE MODELS INDICATE AS MUCH
AS 3 TO 6 INCHES OF SN MAY ACCUMULATE ON SAT/SAT NGT UNDER UPR DVGC/
H85-7 FGEN IN RRQ OF JET MAX OVER ONTARIO IN CONFLUENCE ZN BTWN THE
2 BRANCES ON THE COLD SIDE OF SFC FRONTAL BNDRY...EVEN IF SOME RA
MIXES WITH THE PCPN NEAR LK MI. TENDED TO MAINTAIN HIER POPS ON SUN
OVER THE NCNTRL THAN INDICATED BY ALL BLEND GUIDANCE CONSIDERING THE
POTENTIAL FOR LINGERING LK ENHANCEMENT WITH SHARPER CYC NNW FLOW
SHOWN BY THE MOST CONSISTENT 00Z ECMWF.
&&
.AVIATION /FOR 18Z TAF ISSUANCE/
EXPECT THE CLOUDS TO LINGER THROUGH THE REMAINDER OF THIS AFTERNOON
AND INTO THE EARLY EVENING AS WINDS ARE NORTH TO NORTHWESTERLY OFF
THE LAKE. DRY AIR SEEN ON SATELLITE IS TRYING TO MAKE ITS WAY INTO
THE WESTERN TAF SITES...WITH A DISTINCT CLOUD EDGE MAINLY ALONG THE
WESTERN SHORES OF UPPER MICHIGAN. SOME LAKE EFFECT CLOUD COVER AND
POTENTIALLY SNOW SHOWERS WILL IMPACT KIWD THROUGH THE EARLY
AFTERNOON...THOUGH DO NOT EXPECT ANY SIGNIFICANT REDUCTION IN
VISIBILITIES. THIS IS PRIMARILY ASSOCIATED WITH A SHORTWAVE OVER THE
LAKE...AND LIMITED MOISTURE. ONCE THIS FEATURE PASSES LATE THIS
AFTERNOON AND DRY AIR MAKES ITS WAY INTO THE SITE...EXPECT CEILINGS
TO CLEAR OUT. KCMX WILL SEE A SIMILAR TREND...MINUS THE SNOW
SHOWERS. CONDITIONS SHOULD BE MVFR TO VFR TONIGHT AND THROUGH
TOMORROW AT THESE SITES. AS FOR KSAW...CONDITIONS WILL REMAIN RATHER
SOUPY UNTIL WINDS SWITCH AROUND TO THE NORTHWEST AFTER 00Z. UNTIL
THEN...THE SITE WILL HAVE TO DEAL WITH LIFR/IFR
VISIBILITIES/CEILINGS AND LAKE EFFECT SNOW SHOWERS. EXPECT THE CLOUD
COVER TO DIMINISH A LITTLE SLOWER THAN THE WESTERN SITES...HOWEVER
CONDITIONS SHOULD IMPROVE TO VFR FOR THE OVERNIGHT TIME PERIOD.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
AN ELONGATED LOW PRESSURE TROUGH FROM THE CENTRAL PLAINS TO FAR
EASTERN LAKE SUPERIOR WILL MOVE EAST TODAY. IN ITS WAKE...HIGH
PRESSURE OVER THE NORTHERN PLAINS WILL EXTEND A RIDGE OVER LAKE
SUPERIOR THROUGH FRIDAY MORNING...SINKING SOUTHEASTWARD TO THE
CENTRAL PLAINS. ON FRIDAY THE HIGH WILL MAKE ITS WAY TO THE
NORTHEASTERN STATES. MEANWHILE...LOW PRESSURE SYSTEM OVER HUDSON BAY
WILL DRAG A TROUGH ACROSS LAKE SUPERIOR SATURDAY AFTERNOON THROUGH
SATURDAY NIGHT. AHEAD OF THE TROUGH...EXPECT SOME SOUTHWEST GALE
FORCE GUSTS TO 35 KNOTS FRIDAY AFTERNOON INTO EARLY SATURDAY. HELD
OFF ON ISSUING ANY GALE HEADLINES SINCE GUSTS WILL ONLY MARGINALLY
MEET GALE CRITERIA. A LOW PRESSURE SYSTEM WILL TAKE SHAPE OVER THE
PLAINS SATURDAY NIGHT AND MERGE WITH THE TROUGH ON SUNDAY MORNING AS
IT REACHES LAKE MICHIGAN. THIS LOW WILL MOVE JUST EAST OF LAKE
SUPERIOR ON SUNDAY AFTERNOON AND REACH QUEBEC BY SUNDAY NIGHT.
ANOTHER LOW WILL DROP FROM ALBERTA INTO MINNESOTA SUNDAY
NIGHT...BEFORE MERGING WITH THE LINGERING TROUGH EAST OF LAKE
SUPERIOR BY MONDAY EVENING. THERE IS INCREASED UNCERTAINTY WITH
RESPECT TO WIND DIRECTIONS AND SPEEDS...AND THEREFOR WAVE HEIGHTS
STARTING SUNDAY EVENING. THE UNCERTAINTY IS DUE TO VARIABILITY
BETWEEN FORECAST MODELS ON THE TRACK AND STRENGTH OF THE LOW
PRESSURE SYSTEM COMING IN FROM THE WEST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...KC
DISCUSSION...KC
AVIATION...MCB
MARINE...TITUS
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
1044 AM CST THU DEC 1 2011
.DISCUSSION...
THE MAIN ISSUE IS AREA OF CLOUDS IN CNTRL-WRN ND AND HOW FAR THEY
WILL ADVANCE EAST. AREA OF 2500-3500 FT AGL CLOUDS CONTINUES TO
SPREAD EAST-SOUTHEAST THRU SE SASK INT MANITOBA AND EXTENDS INTO
THE CNTRL PARTS OF ND. MOVEMENT IS EAST AND CLOUDS WOULD SPREAD
INTO THE NRN VALLEY MIDDAY-EARLY AFTN. SRN EDGE OF THE CLOUD AREA
IS MUCH MORE SPOTTY THAN THE NORTH END. LATEST VSBL PIX AND
WEBCAMS SHOWS CLOUDS ARE NOT COMPLETELY SOLID WITH SOME HOLES
FORMING. ALL IN ALL...CONFIDENCE IN THESE CLOUDS...HOW FAR THEY
WILL ADVANCE AND OVERALL EVOLUTION IS LOWER THAN NORMAL. CANT FIND
A REAL MECHANISM WHY THEY ARE THERE. RUC AND 11Z HRRR DO FINALLY
PICK UP ON SOME 925-850 MB MOISTURE ON THE NOSE OF 925-850 MB WARM
ADVECTION. THIS DOES SPREAD IN THE VALLEY..ESP NRN VALLEY...THIS
AFTN. WILL UPDATE GRIDDS FOR THIS IDEA...BUT TRY TO BREAK IT UP SOME.
WILL NOT ALTER TEMPS RIGHT NOW AS WITHOUT SNOWCOVER TEMPS HAVE
BEEN FORECASTING TOO COLD OF LATE.
&&
AVIATION...
WILL NEED TO WATCH HIGH END MVFR-LOW END VFR CLOUDS IN CNTRL ND
THIS AFTN. THEY MOVED INTO DVL AND SHOULD REMAIN AT LEAST IN A
SCT-BKN PHASE TODAY AND POSSIBLY MOVE INTO GFK TOWARD 18-19Z.
&&
.PREV DISCUSSION... /ISSUED 330 AM CST THU DEC 1 2011/
SHORT TERM...
TEMPERATURES AND WINDS ON FRIDAY WILL BE THE PRIMARY FORECAST
ISSUES.
NORTHERLY WINDS ON THE FRONT SIDE OF THE SFC HIGH OVER THE
NORTHERN ROCKIES AND PLAINS WILL CONTINUE TO BRING DRY AIR AT LOW
LEVELS INTO THE CWA THIS MORNING. CLOUDS HAVE BEEN
DECREASING...ALTHOUGH THERE HAS BEEN AN AREA OF STRATUS MOVING
INTO NORTHWESTERN ND FROM CANADA. THE SFC HIGH WILL MOVE SOUTH
THROUGH TODAY AS THE NORTHERN BRANCH SHORTWAVE TROUGH PUSHES
FURTHER EAST. EVEN WITH THE DECREASING CLOUDS...850MB TEMPS IN THE
-10 TO -13 C RANGE WILL KEEP US COOL...PARTICULARLY IN THE
NORTHEASTERN CWA. THE WESTERN COUNTIES MAY BE A BIT WARMER...IN
THE MID TO UPPER 20S...AS WINDS SHIFT TO THE WEST BY AFTERNOON AND
START TO BRING IN SOME WARMER AIR.
TONIGHT...SFC LOW PRESSURE WITH STRENGTHEN OVER SASKATCHEWAN AND
MANITOBA. WINDS WILL INCREASE AGAIN OUT OF THE SOUTHWEST AND
SHOULD KEEP THE BOUNDARY LAYER MIXED IN THE WEST...WHILE GREATER
DECOUPLING IN THE EAST WILL ALLOW TEMPS TO DROP BELOW 10 F IN SOME
PLACES. THE SFC TROUGH WILL CONTINUE INTO FRIDAY...WITH STRONG
SOUTHWESTERLY WINDS. THIS WILL HELP TEMPS GET BACK INTO THE 30S.
NAM AND GFS BOTH HAVE 925MB WINDS GETTING UP ABOVE 40 KTS IN THE
NORTHERN RED RIVER VALLEY BY FRIDAY AFTERNOON. WILL HAVE TO WATCH
THE AREA FOR WINDS APPROACHING ADVISORY CRITERIA.
ANOTHER SHORTWAVE TROUGH WILL MOVE THROUGH THE NORTHERN PLAINS ON
FRIDAY NIGHT...PUSHING THE SFC LOW EAST AND BRINGING A COLD FRONT
THROUGH THE CWA. THE 00Z AND TO A LESSER EXTENT THE 06Z NAM
BREAK OUT PRECIP AHEAD OF THE FRONT FRIDAY NIGHT. THE GLOBAL
MODELS ARE MUCH MORE DRY. WILL KEEP POPS SILENT FOR NOW FRIDAY
NIGHT BUT WILL MONITOR FOR FURTHER DEVELOPMENTS. THERE ARE MORE
INDICATIONS OF SOME LIGHT PRECIP IN THE LAKE OF THE WOODS REGION
SATURDAY AFTERNOON AS THE SYSTEM MOVES OFF THROUGH CANADA...SO
WILL KEEP THE LOW POPS WE HAD GOING IN THAT AREA. THE NEXT SYSTEM
WILL START DIGGING INTO THE MT/ND BORDER SATURDAY NIGHT...WITH THE
SFC LOW DROPPING DOWN INTO WESTERN ND.
LONG TERM...
THE SFC LOW WILL MOVE INTO THE AREA ON SUNDAY...SO CONTINUED WITH
CHANCE POPS FOR SNOW OVER MUCH OF THE CWA. AFTER A BRIEF BREAK
DURING THE EARLY PART OF THE WORK WEEK...ANOTHER FRONTAL BOUNDARY
MOVING THROUGH WILL BRING A CHANCE FOR PRECIP TO THE SOUTHERN
COUNTIES WEDNESDAY NIGHT SO INCLUDED SOME LOW POPS.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
RIDDLE/JR
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1035 AM CST THU DEC 1 2011
.UPDATE...
LOW CLOUDS CONTINUE TO STREAM NORTHWARD WEST OF INTERSTATE 35
AHEAD OF OUR APPROACHING SYSTEM. THE COLD FRONT IS CURRENTLY
LOCATED AS FAR SOUTH AS CHILDRESS AND IS ORIENTED ALMOST STRAIGHT
NORTHWARD. WE SHOULD SEE MORE OF AN EASTWARD PROGRESSION THIS
AFTERNOON AS IT MOVES SLOWLY SOUTH. THE FRONT SHOULD STALL NEAR A
LINE FROM SHERMAN TO FORT WORTH TO COMANCHE AFTER DAYBREAK BEFORE
RETURNING TO THE NORTH AHEAD OF AN APPROACHING UPPER TROUGH.
ISENTROPIC LIFT IS FORECASTED TO BE STRONG AND DEEP BEHIND THE
FRONTAL BOUNDARY OVERNIGHT. MOISTURE AND INSTABILITY LOOK TO BE
BEST ACROSS THE NORTHWEST ZONES AND HAVE UPPED THE POPS TO LIKELY
FOR THESE LOCATIONS. SEVERAL OF THE SHORT-TERM MODELS AND THE GFS
SHOW ENOUGH LIFT ALONG THE BOUNDARY FOR SOME PRECIP AND HAVE
INCLUDED A 20 POP FOR POINTS FROM BONHAM SOUTHWESTWARD INTO THE
METROPLEX. WILL CONTINUE TO ASSESS HOW FAR EAST THE RAIN IS LIKELY
TO BE AND MAY NEED TO RAISE POPS FOR TONIGHT WITH THE AFTERNOON
PACKAGE.
85/NH
&&
.AVIATION...
15Z UPDATE/CONCERNS...
STRONG WARM ADVECTION ON 30KT+ WINDS IN THE 1.5-3 KFT LAYER IS
INDUCING RAPID MVFR STRATUS GROWTH ALONG/WEST OF I-35 CORRIDOR.
CIGS INITIALLY WILL BE EITHER OF 2 KFT. RUC SOUNDINGS SHOW THAT
WARMING TODAY WILL RESULT IN CIGS RAPIDLY RISING TO VFR UNDER 4
KFT BY 17Z...THEN QUICKLY RISING ABOVE 4 KFT BY 18Z AND AFTER.
OTHERWISE...COLD FRONT WILL REMAIN WELL NORTHWEST OF NORTH TX
TERMINALS TODAY. SOUTHEAST WINDS AROUND 10 MPH WILL BACK TO THE
EAST AT/BELOW 10 KTS BY 00Z FRIDAY.
05/
&&
.PREV DISCUSSION... /ISSUED 346 AM CST THU DEC 1 2011/
NO MAJOR CHANGES TO THIS PACKAGE. RAIN IS STILL EXPECTED TO BEGIN
IN WESTERN COUNTIES ON FRIDAY...WITH RAIN LIKELY OVER ALMOST ALL
OF NORTH TEXAS BEGINNING SATURDAY MORNING AND SPREADING EAST
THROUGH SUNDAY MORNING. PRECIP SHOULD SHUT OFF BY SUNDAY NIGHT IN
ALL BUT SOUTHEASTERN COUNTIES WHERE SOME OVER RUNNING PRECIP IS
INDICATED FOR MONDAY. HAVE REMOVED MENTION OF THUNDER IN SOUTHERN
COUNTIES DUE TO VERY MARGINAL CAPE VALUES. THERE MAY BE A
LIGHTNING STRIKE OR TWO SOMEWHERE IN THE SOUTH...BUT REAL
INSTABILITY APPEARS TO REMAIN SOUTH OF THE NORTH TEXAS CWA.
COLD FRONT REACHES NORTHWEST COUNTIES SATURDAY NIGHT AND PUSHES
SOUTHEAST OF SOUTHERN COUNTIES SUNDAY MORNING. AT THIS
TIME...TEMPERATURES APPEAR WARM ENOUGH THAT NO WINTER PRECIP IS
EXPECTED IN NORTH TEXAS. SHOULD THE COLD FRONT ARRIVE EARLIER AND
STRONGER...NORTHWEST COUNTIES MAY SEE SOME FREEZING RAIN SUNDAY
MORNING. WILL CONTINUE TO MONITOR MODEL TRENDS ON
TEMPERATURES/FROPA TIMING.
REST OF THE WEEK LOOKS COOL AND DRY. WITH LIGHT WINDS...CLEAR
SKIES...AND COOL DRY AIR MASS...WEDNESDAY MORNING LIKELY TO BE
BELOW FREEZING OVER THE ENTIRE NORTH TEXAS AREA. ECMWF/GFS PROG
MOISTURE RETURN ON DAY 8 FRIDAY...BEYOND SCOPE OF THIS FORECAST.
84
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 64 50 60 54 65 / 5 20 40 40 70
WACO, TX 67 53 64 56 68 / 5 10 40 40 60
PARIS, TX 62 45 59 46 62 / 5 10 20 30 70
DENTON, TX 63 46 57 54 64 / 5 20 40 50 70
MCKINNEY, TX 63 46 58 51 64 / 5 20 30 40 70
DALLAS, TX 64 51 61 53 65 / 5 20 30 40 70
TERRELL, TX 64 47 61 51 64 / 5 10 30 30 60
CORSICANA, TX 67 50 66 54 68 / 5 10 30 30 60
TEMPLE, TX 67 53 64 56 68 / 5 10 40 50 60
MINERAL WELLS, TX 63 46 56 56 63 / 10 50 50 60 70
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
85/85