Forecast Discussions mentioning any of
"HRRR" "RR" "RUC13" "RUC" received at GSD on 12/07/11
AREA FORECAST DISCUSSION
NWS DENVER CO
1149 PM MST SUN DEC 4 2011
.UPDATE...HAVE DECIDED TO CANCEL THE REMAIN PORTION OF THE WINTER
WEATHER ADVISORY. RADAR COVERAGE CONTINUES TO SHRINK FROM NORTH TO
SOUTH ACROSS THE DENVER AREA. ANY ADDITIONAL ACCUMULATIONS WILL BE
SOUTH OF THE DENVER AREA AND LESS THAN AN INCH.
&&
.AVIATION...SHUD SEE ANY LINGERING SNOWFALL AROUND THE DENVER AREA
DIMINISH BY 09Z...WITH A GRADUAL IMPROVEMENT IN THE CIGS THROUGH
THE EARLY MORNING HOURS. COULD SEE CIGS OF 4-5 KFT IMPROVE SOONER
THAN IS REFLECTED IN THE CURRENT TAFS WHICH SHOWS THOSE CIGS IN
PLACE UNTIL 18Z...THOSE TRENDS MAY NEED TO BE SPED UP ON THE NEXT
TAF ISSUANCE.
&&
.PREV DISCUSSION... /ISSUED 803 PM MST SUN DEC 4 2011/
UPDATE...
SHORT TERM...LATEST DATA SUGGEST BEST CHANCE FOR ACCUMULATING
SNOWS OVERNIGHT WILL BE MAINLY FROM DENVER SOUTH TO THE PALMER
DIVIDE AND OVER THE SRN FOOTHILLS AND PARK COUNTY. HAD A BURST OF
HEAVIER SNOW FM LATE AFTN INTO THE EARLY EVENING HOURS WHICH
PRODUCED FROM 3 TO 6 INCHES OF SNOW IN THE SRN FOOTHILLS INTO PARK
COUNTY. WILL LEAVE ADVISORIES IN PLACE FOR THE DENVER METRO AREA
BUT SNOW AMOUNTS LOOK TO BE MORE IN THE 2 TO 3 INCH RANGE. FURTHER
NORTH AND EAST SNOW POTENTIAL DOES NOT LOOK THAT GREAT SO WILL
DROP ADVISORIES IN THE NRN FOOTHILLS AND IN THE FORT COLLINS AND
GREELEY AREAS.
AVIATION...RIGHT NOW SNOW AMOUNTS AT DIA AND BJC SHOULD BE IN
THE 1 TO 2 INCH RANGE WITH UP TO 3 INCHES AT APA. LATEST DATA
SUGGEST LIGHT SNOW WILL GRADUALLY END BY 2 AM OR 3 AM AT DIA WITH
ONLY FLURRIES THROUGH SUNRISE.
PREV DISCUSSION... /ISSUED 250 PM MST SUN DEC 4 2011/
SHORT TERM...BROAD UPPER TROF COVERS MUCH OF THE WESTERN U.S. WHILE
WATER VAPOR IMAGERY SHOWING NEXT DISTURBANCE DROPPING SOUTH INTO THE
MEAN TROF POSITION OVER UTAH. RUC QG FIELDS SHOWING BEST UPWARD
FORCING OVER WESTERN CO AND WESTERN WYOMING. THE ASSOCIATED COLD
FRONT IS MOVING SOUTH FROM SOUTHERN WYOMING INTO NORTHERN COLORADO
WITH GUSTY NORTHERLY WINDS DEVELOPING BEHIND THE FRONT. CEILINGS ARE
BEGINNING TO LOWER OVER THE FRONT RANGE WITH SOME VERY LIGHT ECHOES
DEVELOPING OVER THE FOOTHILLS. OVERALL...FORECAST IS STILL ON TRACK
WITH MAIN CONCERN SNOW AMOUNTS FOR UPCOMING STORM. SNOW AMOUNTS
EXPECTED TO BE A BIT LOWER THAN THE LAST STORM...AS QG VERTICAL
VELOCITY FIELDS SHOWING THE BEST FORCING ACROSS WESTERN COLORADO
WITH LESSER FORCING OVER NORTHEAST COLORADO AND OVERALL MOISTURE IS
A BIT LOWER. HIGHEST SNOW AMOUNTS WILL BE OVER THE EAST SLOPE FRONT
RANGE FOOTHILLS WITH LESSER AMOUNTS AS YOU MOVE EAST AWAY FROM THE
FOOTHILLS. THERE IS SOME GOOD LOW LEVEL INSTABILITY WITH UPSLOPE UP
TO AROUND 600MB. WILL KEEP THE CURRENT 3-6 SNOWFALL RANGE OVER THE
URBAN CORRIDOR BUT WOULDN`T BE SURPRISED IF AMOUNTS END UP BEING A
BIT LOWER. BIG DROPOFF OF SNOW EAST OF INTERSTATE 25 AND AM
CONCERNED THAT THERE WON`T BE MUCH SNOW OVER EASTERN WELD COUNTY AND
ZONE 45 AND 46 WITH CURRENT ADVISORIES. WILL LEAVE IN PLACE FOR NOW.
FOR THE FOOTHILLS WILL STILL GO WITH 5 TO 10 INCHES. EVEN COLDER
TEMPERATURES FOR TONIGHT AND MONDAY WITH READINGS IN THE SINGLE
DIGITS AND LOWER TEENS FOR THE NEXT 24 HOURS.
LONG TERM...COULD STILL SEE A FEW FLURRIES OCCURRING SOUTH ON
INTERSTATE 70 AS THE STORM CONTINUES TO MOVE SOUTH AND COLD HIGH
PRESSURE SETTLES IN. TEMPERATURES WILL CONTINUE TO PLUMMET TO BELOW
ZERO ACROSS THE AREA. WILL LIKELY SEE VERY COLD TEMPERATURES IN THE
HIGH MOUNTAIN VALLEYS...DROPPING TO AROUND -20 TO -30 BY EARLY
TUESDAY MORNING.
THE PERSISTENT UPPER TROUGH WILL FINALLY MOVE SOUTHEAST OF THE AREA
WITH A SHORT WAVE UPPER RIDGE MOVING OVERHEAD HOWEVER FLOW ALOFT
WILL STILL BE NORTHERLY. TEMPERATURES WILL WARM SLIGHTLY...BUT HAVE
KEPT TEMPERATURES COOLER THAN GUIDANCE AS THE RECENT COLD AIRMASS
WILL BE HARD TO SCOUR OUT AND THE SNOW ON THE GROUND WILL LIKELY
HAVE AN AFFECT AS WELL. HAVE KEPT HIGHS IN THE TEENS TO UPPER 20S
FOR TUESDAY. ON WEDNESDAY...FLOW ALOFT WILL TURN WESTERLY AS A BROAD
UPPER TROUGH OVER CANADA DROPS SOUTH. THE WEST WINDS WILL HELP
TEMPERATURES WARM DURING THE DAY...THEN A WEAK COLD FRONT WILL DROP
SOUTH DURING THE NIGHT. NO REAL PRECIPITATION EXPECT THAT
NIGHT...HOWEVER IT WILL RESULT IN COOLER TEMPERATURES AND A SLIGHT
CHANCE OF SNOW THURSDAY AS ANOTHER SHORTWAVE TROUGH ROUNDS THE
BOTTOM OF THE LARGER TROUGH.
THE LARGE SCALE PATTERN WILL CONTINUE TO TRANSITION EAST FRIDAY TO
BRING A STRONGER UPPER RIDGE OVER THE ROCKIES BRINGING DRIER WEATHER
AND RELATIVELY WARMER AIR FRIDAY AND SATURDAY. INTRODUCING A SLIGHT
CHANCE OF PRECIPITATION FOR SUNDAY AS MODELS DISAGREEING ON WHETHER
THERE WILL BE ANOTHER TROUGH OR RIDGE OVER THE AREA.
AVIATION...CEILINGS BEGINNING TO LOWER NORTH OF THE LOCAL TERMINALS
WITH CIGS OF 5000-7000 FEET AGL UPSTREAM OVER FNL AND GXY. THIS WILL
RESULT IN ILS APPROACHES AROUND 23Z AT DEN AND BJC. THE LIGHT SNOW
NOT FAR BEHIND WITH SNOW NOW AT CYS. MORE WIDESPREAD SNOW AT LOCAL
AIRPORTS DEVELOPING BETWEEN 02-3Z AND CONTINUING THROUGH ABOUT 08Z.
THIS WILL BE THE WINDOW OF MOST OF THE ACCUMULATION SNOW. MOST OF
THE SNOW WILL BECOME VERY LIGHT AND JUST FLURRIES DURING THE DAY ON
MONDAY WITH ACCUMULATIONS UNDER AN INCH. STILL TOTAL ACCUMULATIONS
OF 3 TO 6 INCHES...WITH 2-3 AT DIA...3-4 AT APA AND 4 TO 6 AT BJC.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...COOPER
LONG TERM....MEIER
AVIATION...COOPER
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
902 PM CST TUE DEC 6 2011
.DISCUSSION...
900 PM CST
AS ANTICIPATED...CLOUDS ARE MAKING IT EXTRA CHALLENGING WITH THE
TEMPERATURE FORECAST TONIGHT. THE CLEARING WAS SHORT-LIVED...WITH
CLOUDS BOTH EXPANDING AND ADVECTING BACK EAST WITHIN AND JUST ON
THE BACKSIDE OF THE LOW-LEVEL RIDGE. AN UPPER LEVEL TROUGH ALOFT
OVER THE AREA IS CONTINUING TO SHEAR OUT...WITH SUPPRESSION
APPARENTLY INCREASING LOOKING AT THE WATER VAPOR SATELLITE. THE
EVENING DVN AND ILX SOUNDINGS DEPICTED A FAIRLY DEEP 3000 FT LAYER
AT SATURATED OR NEAR-SATURATED...AND THERE ARE FEW SIGNS OF HOLES
EXISTING WITHIN THE CLOUD RIBBON. DESPITE THAT...THE BACK EDGE IS
PROGRESSING...LOCATED ABOUT 100 MILES WEST OF THE MISSISSIPPI
RIVER AROUND 9 PM. THE NAM AND RUC ANALYSES OF 925-850MB MOISTURE
CAPTURE THIS WELL AND THE PROGRESSION OF THIS. THEIR DRYING
FORECAST COMES ACROSS NORTHERN IL FROM 3 AM THROUGH
DAYBREAK...COINCIDENT WITH THEIR DEPICTION OF HIGHER Q-VECTOR
DIVERGENCE /A PROXY FOR THE SUPPRESSION MENTIONED EARLIER/. THE
LAMP GUIDANCE HAS A VERY GOOD HANDLE ON THE STEADY TEMPERATURES
UNDER THE CLOUD COVER AND SHOW A LATE NIGHT DROP...ESPECIALLY IN
THE WESTERN FORECAST AREA. HAVE STEERED THIS AND THE RUC TREND
INTO THE FORECAST. OVERALL...MINIMUMS ARE SLIGHTLY WARMER FOR MOST
PLACES...A FEW DEGREES TOTAL FOR SOUTH AND EAST OF CHICAGO WHICH
SHOULD SEE THE CLOUDS ARRIVE SHORTLY AND LAST ALL THE WAY THROUGH
DAYBREAK.
MTF
PREVIOUS DISCUSSION...
417 PM CDT
SHORT TERM...THIS AFTERNOON THROUGH FRIDAY
MAIN CONCERN THIS PORTION OF THE FORECAST CENTERS ON LIGHT SNOW
CHANCES THURSDAY NIGHT INTO EARLY FRIDAY AND THEN BLAST OF ARCTIC
AIR FRIDAY INTO EARLY SATURDAY.
AFTERNOON WATER VAPOR IMAGERY SHOWS MID LEVEL TROUGHING ACROSS THE
REGION...WHILE AT THE SURFACE...HIGH PRESSURE STRETCHES FROM THE
WESTERN GREAT LAKES SOUTHWEST TO THE SOUTHERN PLAINS. ON VISIBLE
SATELLITE...EVER PRESENT STRATUS ACTUALLY HAS ERODED A BIT THIS
AFTERNOON FROM THE NORTH AS HIGH PRESSURE BUILDS IN. SUSPECT HOWEVER
THAT STRATUS WILL TEMPORARILY RETURN THIS EVENING AS FLOW BECOMES
NORTHERLY THEN WESTERLY. MODEL RH PROGS SHOW PLENTIFUL MOISTURE
BELOW 800 MB UNTIL LATER TONIGHT. THEN EXPECT THE REMAINING OVERCAST
TO ERODE FROM NORTHWEST. WITH CHILLY AIR MASS IN PLACE...TIMING OF
CLEARING TONIGHT WILL HAVE IMPACT ON LOW TEMPERATURES. THINK THAT
SKIES WILL CLEAR ENOUGH BY TOMORROW MORNING SO THAT...ALONG
WITH LIGHT WINDS...TEMPERATURES WILL BE ABLE TO PLUMMET TO THE UPPER
TEENS ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS. THE
REMAINDER OF THE AREA CAN EXPECT LOW TO MID 20S...WITH UPPER 20S IN
AND NEAR DOWNTOWN CHICAGO. WENT CLOSE TO MAV/MET GUIDANCE FOR LOWS
AND SLIGHTLY COLDER THAN PREVIOUS ISSUANCE.
WEDNESDAY WILL START OUT MOSTLY SUNNY...BUT CLOUDS MAY INCREASE JUST
A BIT IN THE AFTERNOON AS A COLD FRONT SWINGS THROUGH THE AREA
DURING THE AFTERNOON. LOW LEVELS WILL BE EXTREMELY DRY SO NO
PRECIPITATION IS FORECAST WITH THE FROPA. HIGHS WILL TOP OUT NEAR OR
JUST BELOW AVERAGE...LOW 30S OVER NORTH CENTRAL ILLINOIS AND MID 30S
FOR THE REMAINDER OF THE AREA. FROPA WILL SEND REINFORCING SHOT OF
COLDER AIR ACROSS REGION...AS TEMPERATURES COOL AT H85 WEDNESDAY
NIGHT TO ROUGHLY -8C. PRESSURE GRADIENT WILL REMAIN TIGHT ENOUGH TO
KEEP A WESTERLY BREEZE GOING...WITH LOWS LIKELY SIMILAR TO TONIGHT.
THURSDAY WILL BE A FEW DEGREES COOLER THAN WEDNESDAY...WITH CLOUDS
INCREASING FROM THE WEST AS A WAVE DEVELOPS WEST OF THE AREA ALONG
A TIGHT BAROCLINIC ZONE...WITH THE BULK OF ARCTIC AIR OVER THE
NORTHERN PLAINS AND UPPER MIDWEST NORTH OF OUR AREA. ON THURSDAY
NIGHT...DIGGING H5 TROUGH WILL SPAWN A WEAK SURFACE LOW WHICH WILL
TRACK ACROSS THE NORTHERN GREAT LAKES AND SEND AN ARCTIC
FRONTAL BOUNDARY TOWARD THE AREA. THE FRONTOGENETIC FORCED WAVE
ALONG THE ARCTIC FRONT WILL TRACK ALONG THE TIGHTEST THERMAL PACKING
TO NEAR OR OVER OUR AREA. MOST GUIDANCE...WITH THE EXCEPTION
OF THE NAM AND SREF HAVE COME INTO DECENT AGREEMENT ON A BAND OF
LIGHT QPF OVER ALL OF NORTHERN ILLINOIS AND NORTHWEST INDIANA ON
THURSDAY NIGHT INTO EARLY FRIDAY. TIME HEIGHTS AND SOUNDINGS
CONTINUE TO SHOW ADEQUATE SATURATION AND LIFT INTO THE FAVORABLE
DENDRITIC GROWTH AREA. THE RIGHT ENTRANCE REGION OF JET MAY PROVIDE
SOME ENHANCED LIFT. WITH COLD TEMPERATURES IN PLACE...EXPECTING 20:1
RATIO...WHICH WOULD RESULT IN THE FIRST LIGHT ACCUMULATING SNOWFALL
OF THE SEASON FOR MUCH OF THE AREA. AT THIS POINT...POTENTIAL EXISTS
FOR SOME LOCATIONS TO SEE IN EXCESS OF ONE INCH OF SNOWFALL. NOT
HIGH CONFIDENCE YET ON THIS FEATURE...SO DID STAY WITH CHANCE POPS
AS OPPOSED TO HIGHER POPS. IT MAY COME DOWN TO VERY CLOSE TO THE
EVENT UNTIL THE PART OF THE AREA WITH THE BEST FORCING FOR LIGHT
SNOW IS ASCERTAINED. ONCE WAVE QUICKLY SHIFTS EAST THROUGH THE
AREA...THE BIG STORY WILL BE SHARP COLD ADVECTION...WITH MINUS
TEEN TEMPERATURES AT H85 POISED TO POUR INTO AREA. WENT WITH BLENDED
MODEL GUIDANCE FOR LOWS EARLY FRIDAY MORNING...WHICH YIELDS UPPER
TEENS FAR NORTHERN ILLINOIS TO THE LOWER AND MIDDLE 20S FARTHER
SOUTH.
WITH STRONG COLD AIR ADVECTION ONGOING ON FRIDAY...IT WILL BE VERY
DIFFICULT TO RECOVER MUCH FROM THESE LOW TEMPERATURES. MODELS DIFFER
ON HOW COLD WE GET AT H85 AS THERMAL TROUGH REACHES AREA ON FRIDAY.
BUT THE GENERAL RANGE IS ABOUT -15C TO -20C. THUS WENT COLDER THAN
PREVIOUS FORECAST ISSUANCE BY SEVERAL DEGREES FOR FRIDAY...WITH LOW
20S FAR NORTH AND MIDDLE AND UPPER 20S ALONG AND SOUTH OF INTERSTATE
80. SOME LIGHT SNOW MAY LINGER OVER THE EASTERN PORTION OF THE
FORECAST AREA BEFORE SHIFTING EAST BY THE AFTERNOON.
LONG TERM...FRIDAY NIGHT THROUGH TUESDAY NIGHT
GUIDANCE HAS CONTINUED TO TREND COLDER WITH LOW TEMPERATURES
FRIDAY NIGHT...CAPTURED WELL BY A BLEND OF MODEL GUIDANCE AND
PREVIOUS FORECAST. ARCTIC HIGH WILL STRETCH ACROSS AREA...ALLOWING
FOR LIGHT WINDS AND STRONG RADIATIONAL COOLING OVERNIGHT. IF MINOR
SNOW COVER IS IN PLACE...FORECAST LOWS IN THE LOWER TO MIDDLE TEENS
FOR MUCH OF THE AREA OUTSIDE THE CHICAGO HEAT ISLAND MAY STILL END
UP BEING A FEW DEGREES TOO HIGH. SATURDAY WILL START OUT QUITE
COLD...BUT WARM ADVECTION ALOFT AND SOUTHWESTERLY FLOW AT THE
SURFACE WILL ALLOW FOR SOME RECOVERY TO THE UPPER 20S TO AROUND 30
DEGREES. FOR THE REMAINDER OF THE EXTENDED...THE AREA WILL REMAIN
INFLUENCED BY RIDGING OVER THE EASTERN CONUS...SO SOUTHWESTERLY
FLOW...DRY CONDITIONS...AND TEMPERATURES RETURNING TO SLIGHTLY ABOVE
NORMAL...OR AROUND 40 DEGREES...CAN BE EXPECTED. THERE MAY BE A COLD
FRONTAL PASSAGE DAY 6 OR DAY 7...BUT EVEN THAT MAY BE A DRY FROPA.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 02Z...
* VARIABLE CIGS THIS EVENING...MVFR RETURNING LATE THIS
EVENING...AND POTENTIAL FOR IFR.
* LIGHT WINDS BECOMING WEST...WSW OVERNIGHT. BMD
//DISCUSSION...UPDATED 00Z...
MAIN FORECAST CONCERNS WILL BE DEALING WITH VARIABLE CIGS AND
BACKING WINDS AS RIDGE AXIS SLIDES ACROSS THE REGION. SKIES HAVE
CLEARED OUT OVER MOST OF NORTH CENTRAL AND NORTHEASTERN ILLINOIS
THIS EVENING...HOWEVER NARROW BAND OF STRATUS UNDER THE RIDGE
AXIS WITH MVFR AND OCCASIONAL IFR CIGS SPANNING ACROSS
NORTHWESTERN ILLINOIS AND EASTERN IOWA. THIS MOISTURE WILL MOVE
EAST AHEAD OF THE RIDGE...WITH POTENTIALLY MVFR CIGS RETURNING
OVERNIGHT. MOS GUIDANCE DOES NOT HANDLE THIS MOISTURE
WELL...HOWEVER NAM/RUC 925MB RH FIELDS DO INDICATE LOW LEVEL
MOISTURE RETURNING AFTER MIDNIGHT LOCAL TONIGHT TO THE CHICAGO
AREA TERMINALS. LOW LEVEL MOISTURE IS EXPECTED TO PUSH OUT OF THE
AREA MID TO LATE MORNING WITH ADDITIONAL HIGH AND MID CLOUDS
MOVING IN FROM THE NORTH ALONG THE TAIL END OF A COLD FRONT. NO
PRECIP IS EXPECTED...HOWEVER WINDS ARE EXPECTED TO TURN BACK TO
THE WNW BY LATE WEDNESDAY AFTERNOON/EARLY EVENING. BMD
//ORD AND MDW CONFIDENCE...UPDATED 02Z...
* MEDIUM TO HIGH CONFIDENCE IN WIND FORECAST.
* LOW TO MEDIUM CONFIDENCE IN DETAILS OF CIG FORECAST. BMD
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY...SLIGHT CHANCE OF SNOW OVERNIGHT. IFR/MVFR POSSIBLE.
FRIDAY...VFR.
SATURDAY...MVFR POSSIBLE.
SUNDAY...VFR.
MONDAY...VFR.
BMD
&&
.MARINE...
158 PM CST
A SURFACE RIDGE OF HIGH PRESSURE EXTENDING FROM THE PLAINS
NORTHEASTWARD ACROSS THE UPPER GREAT LAKES REGION WILL SLOWLY SAG
SOUTHWARD TONIGHT AS A STRONG AREA OF LOW PRESSURE MOVES INTO
THE HUDSON BAY. AS THIS SURFACE RIDGE MOVES ACROSS LAKE MICHIGAN
THERE WILL BE A PERIOD OF LIGHTER WINDS THIS EVENING. HOWEVER...THIS
WILL BE SHORT LIVED AS THE WINDS WILL BECOME WEST SOUTHWESTERLY AND
INCREASE TO NEAR 30 KT LATER TONIGHT ACROSS THE NORTHERN HALF OF THE
LAKE. THESE WINDS WILL CONTINUE LAKE-WIDE DURING THE DAY ON
WEDNESDAY AS A COLD FRONT MOVES SOUTH ACROSS THE LAKE. THERE COULD
BE A PERIOD OF LOW END GALES AS THE COLD AIR BEGINS TO PUSH ACROSS
THE LAKE WEDNESDAY NIGHT INTO THURSDAY. HOWEVER...WIDESPREAD 30 KT
WITH SOME GALE FORCE GUSTS APPEARS TO BE THE MOST LIKELY AT THIS
TIME.
WINDS ACROSS LAKE MICHIGAN LOOK TO REMAIN IN THE 15 TO 25 KT RANGE
INTO FRIDAY AS THE PRESSURE GRADIENT BETWEEN THE LOW ACROSS THE
HUDSON BAY AND HIGH PRESSURE ACROSS THE PLAINS REMAINS ELEVATED.
ANOTHER SURGE OF HIGHER WINDS...POTENTIALLY GALE FORCE...LOOKS TO
OCCUR ON SATURDAY AS ANOTHER AREA OF LOW PRESSURE TRACKS ACROSS
SOUTHERN CANADA.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1024 AM CST MON DEC 5 2011
.DISCUSSION...
340 AM CST
CHILLY NORTHWEST FLOW AND A PLETHORA OF CLOUDS WILL BE THE MAIN
STORY FOR TODAY ACROSS THE CWA. AT THE SURFACE HIGH PRESSURE WILL
SLOWLY BUILD SOUTH FROM THE UPPER MISSISSIPPI VALLEY OVER THE NEXT
FEW DAYS AS AN INVERTED TROUGH STRETCHES NORTH FROM THE WESTERN
GULF...THROUGH WESTERN KENTUCKY THIS MORNING. THE MAIN PRECIP
BANDING THAT MOVE THROUGH YESTERDAY IS HANGING AROUND THE VICINITY
OF THE INV TROF/STALLED OUT FRONTAL BOUNDARY. A FEW WIGGLES IN THE
FLOW ARE NOTED ON WV IMAGERY MOVING UP THE BOUNDARY...BUT THE
OVERALL BEST CHANCES FOR PRECIP WILL REMAIN WELL TO THE SOUTHEAST. THAT
SAID...A WEAK CONVERGENT BOUNDARY STRETCHING FROM NORTHWESTERN
WI...SOUTHEAST TOWARDS THE SOUTHERN LAKE WILL CONTINUE TO SLIDE
SOUTH THROUGH THE DAY...BRINGING CHANCES FOR LIGHT SNOW SHOWERS TO THE
NORTH AND NORTHWESTERN COUNTIES. OVERALL MOISTURE PROFILES ARE
SHALLOW...BUT POTENTIALLY SUPPORTIVE OF DRIZZLE...AND WITH SURFACE
TEMPS AT OR BELOW FREEZING...WOULDNT BE SURPRISED TO SEE SOME U.P.
AND OR -FZDZ REPORTS ACROSS THE FAR NORTHWESTERN COUNTIES THIS
MORNING. SURFACE TEMPERATURES MAY FLIRT ENOUGH WITH FREEZING THAT
IMPACTS WOULD BE LIMITED TO EXPOSED AND ELEVATED SURFACES.
BEHIND THE CONVERGENT BOUNDARY...FLOW WILL BECOME NORTHEASTERLY AND
INCREASE THE CHANCES FOR LAKE EFFECT SNOWS ACROSS NE IL. BUFR AND
MODEL GUIDANCE MAINTAIN A NORTHEASTERLY COMPONENT IN THE LOWEST
200 MB... WITH SATURATION AND LAKE INDUCED CAPES UP TO 6KFT
THROUGH TOMORROW AFTERNOON. THIS IS A LITTLE DIFFERENT FROM
PREVIOUS DAYS /IE SLOWER/...AS THE AREA OF HIGH PRESSURE ACROSS
THE PLAINS SLOWLY DROPS SOUTH...AND WOULD BE SLUGGISH AT
TRANSITIONING THE SNOWS INTO THE TYPICAL LAKE/PORTER COUNTY
INDIANA LOCATIONS. LATEST COBB OUTPUT DOES SQUEEZE OUT JUST UNDER
A HALF INCH OF SNOW FOR AREAS IN LAKE AND COOK COUNTY. OVERNIGHT
TONIGHT AND INTO TOMORROW...ANY LES SHOULD BEGIN AS SNOW...BUT
PROFILES ARE WARMING THE SURFACE TO ABOVE FREEZING INTO THE
MORNING HOURS. DEW POINT DEPRESSIONS NOT PROGGED TO BE VERY HIGH
SO EXPECT WET BULBS AT THE SURFACE TO REMAIN JUST AOA FREEZING
INTO THAT TIME. SO EXPECT TRANSITION TO SNOW WITH A MIX OF
RAIN...BUT DEPENDING ON HOW SLUGGISH PROFILES ARE TO WARM AT THE
SURFACE...IT MAY REMAIN MORE FROZEN THAN ANYTHING WITH SOME
SPRINKLES MIXED IN. THE LATEST IN HOUSE AND NATIONAL WRF /NMM AND
ARW/ DEVELOP THIS BOUNDARY LATE TONIGHT ALONG THE LAKE/COOK LAKE
SHORE BEYOND 06Z TONIGHT. OVERALL QPF VALUES ARE PRETTY LOW AND
RANGE FROM 0.02 TO 0.05". GIVEN THE FACT THAT TEMPS ARE NOT TOO
COLD...SNOW TO LIQUID RATIOS SHOULD BE PRETTY TYPICAL 10:1 AND NOT
HIGHER...BUT LIKELY A SMIDGEN LOWER. SO ANTICIPATING NO MORE THAN
A QUARTER OF AN INCH TO MAYBE A HALF OF AN INCH IN SOME OF THE
INTENSE SHOWERS THAT WIGGLE THROUGH. ONE INTERESTING FEATURE
TONIGHT IS THAT THE REGIONAL GEM DEVELOPS A WEAK MESO LOW ACROSS
THE SOUTHERN HALF OF THE LAKE...DUMPING 4+ INCHES OF SNOW ACROSS
RACINE/KENOSHA/LAKE AND EVEN MCHENRY COUNTIES TONIGHT AND INTO
TOMORROW MORNING. THE PREVIOUS RGEM RUNS SHOWED SIMILAR
OUTCOMES... BUT MORE ACROSS LAKE COUNTY INDIANA/COOK COUNTY AND
NOWHERE NEAR AS INTENSE AS THE CURRENT RUN. WILL MONITOR TO SEE IF
TRENDS LEAN IN A HIGHER DIRECTION BUT FOR NOW WILL KEEP IT IN THE
SUB HALF IN RANGE.
A PRACTICALLY STATIONARY UPPER LEVEL TROUGH ACROSS THE WESTERN
CONUS WILL BEGIN TO SWING BEYOND THE REGION OVERNIGHT TUESDAY AND
INTO WEDNESDAY WHILE RIDGING AT THE SURFACE BUILDS. CONDITIONS
ACROSS THE AREA SHOULD REMAIN QUIET THROUGH THE END OF WITH WEEK.
OVERNIGHT ON THURSDAY A WEAK CLIPPER WILL ZIP THROUGH THE REGION
AND BRING THE CHANCES FOR A QUICK DUSTING OF SNOW. GUIDANCE IS
STILL GOING BACK AND FORTH ON HOW MUCH TO HANDLE A DIGGING TROUGH
AND SHEARED OUT VORT THAT WILL DIP THROUGH THE NORTHERN PLAINS IN
THAT TIME. THE 00Z GFS IS MOVING THROUGH THE CWA DRY WHILE THE ECMWF
HAS BEEN PRETTY CONSISTENT TO SHOW SOME -SN INTO THE EARLY
AFTERNOON HOURS. WITH THE VARIABILITY AT THIS RANGE WILL LIMIT
MENTION TO ONLY A SLIGHT CHANCE. IF/WHEN TRENDS ALIGN...WILL NUDGE
UPWARDS. THE OTHER SEMI-CONSISTENT STORY BEYOND THE TROUGH AND
INTO FRIDAY/THE WEEKEND IS THE SURGE OF COLD AIR SPILLING IN FROM
CANADA. THERE IS STILL A STRONG INDICATION THAT H85 TEMPS WILL
DROP ANYWHERE FROM -15 TO -20. THE EC HAS CONTINUALLY BEEN THE
MOST AGGRESSIVE OVER THE LAST FEW NIGHTS...WHILE THE GFS HAS BEEN
SCALING BACK SLIGHTLY. RAW GUIDANCE SUGGESTS MAX TEMPS MAY
STRUGGLE TO WARM ABOVE THE LOW 20S FRI...BUT WONDER IF THAT MAY BE
A LITTLE TOO WARM. THE BIG SAVING GRACE IS THE LACK OF SOLID SNOW
PACK...IF THAT WERE PRESENT...IT WOULD BE MUCH COLDER. THE DIP TO
COLD TEMPS SHOULD BE SHORT LIVED AS A THERMAL RIDGE IS PROGGED TO
BUILD IN LATE ON THE WEEKEND AS FLOW FLIPS TO SOUTHWESTERLY
THROUGH THE COLUMN. SHEA
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* CEILING TRENDS TODAY.
* LAKE EFFECT SHOWERS LATE MORNING THROUGH EARLY AFTERNOON.
TRS
//DISCUSSION...UPDATED 16Z...
INITIAL BAND OF LAKE EFFECT SHOWERS HAVE WEAKENED AS THEN MOVED
INLAND OVER FAR SE WI...EXTREME NE IL AND FAR NW IND. ANOTHER BAND
OF LAKE EFFECT IS CURRENTLY MOVING ASHORE IN NE IL AND FAR SE WI
WHERE LOW LEVEL CONVERGENCE ALONG A SFC TROF AND WSHFT LINE.
LATEST RUNS OF HRRR AND RUC13 HAVE DELAYED THE ARRIVAL OF THE
WSHFT AND THE AXIS OF MAX SFC CONVERGENCE AT ORD AND MDW BY AN HR
OR TWO. EXTRAPOLATION OF MOVEMENT OF LAKE BAND OVER LAST HR OR SO
HAS PUSHED ARRIVAL AT ORD SLIGHTLY THOUGH NOT AS SLOW AS MODELS
INDICATE. WITH SRN MID LAKE BUOY REPORTING 41F FOR BOTH AIR AND
WATER TEMPS ALONG WITH NORTHERLY ISLAND AT 41F WITH DWPT 33F
EXPECT TO SEE -SHRA OR -SHSNRA DO TO WARM LLVLS...ESPECIALLY OVER
CORE OF URBAN AREA. ALSO FCST TEMP PROFILES KEEPING LAKE EFFECT
CLOUD TOPS NO COLDER THAN -6 TO -7 C...TOO WARM FOR VERY MANY ICE
CRYSTALS. THESE FORECAST TEMPS VERIFIED BY RECENT AIRCRAFT TEMP
PROFILES FROM ORD ARRIVALS AND DEPARTURES.
BASED ON TRENDS JUST UPSTREAM OVER SE WI AND EXTREME NE IL EXPECT
TO SEE MVFR CIGS CONTINUE FURTHER SOUTH AND LOWER A BIT AND ALSO
SOME REDUCTION OF VSBY TO MVFR IN SHOWERS. SMALL AREA OF IFR
CIGS PERSIST OVER PARTS OF FAR SE WI THOUGH HAVE PUSHED INLAND
FROM MKE...RAC AND ENW. MAY BRIEFLY EXPERIENCE IFR CIGS AT ORD
AND MDW AROUND TIME OF THE WSHFT TO OUT OF THE NNE.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM CONFIDENCE ON CEILING TRENDS AND VISIBILITY TRENDS.
* MEDIUM CONFIDENCE ON TIMING AND COVERAGE OF LAKE EFFECT SHOWERS.
* HIGH CONFIDENCE ON GENERAL WIND SPEEDS AND DIRECTIONS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY...VFR. CHANCE OF SNOW SHOWERS NEAR THE LAKE.
WEDNESDAY...VFR.
THURSDAY...VFR. SLIGHT CHANCE OF SNOW SHOWERS THURSDAY NIGHT.
FRIDAY THROUGH SUNDAY...VFR.
LENNING
&&
.MARINE...
309 AM CST
HIGH PRESSURE QUICKLY SPREADING ACROSS THE NORTHERN AND CENTRAL
PLAINS TODAY WHILE A TROUGH OF LOW PRESSURE EXTENDING FROM QUEBEC TO
THE TEXAS GULF COAST MORE SLOWLY MOVES EAST...THE PRESSURE GRADIENT
WILL STRENGTHEN OVER LAKE MICHIGAN LEADING TO INCREASING GENERALLY
NORTHERLY WINDS. THIS WILL ALSO INCREASE COLD ADVECTION OVER THE
LAKE...DRIVING WAVE HEIGHTS TO INCREASE QUICKLY AS WINDS INCREASE
TO 15 TO 25 KT. WHILE NO GALES ARE EXPECTED TO DEVELOP AT THIS
TIME...WAVES PILING UP AT THE SOUTHERN END OF THE LAKE WILL LEAD TO
WINDS AND WAVES HAZARDOUS TO SMALL CRAFT DEVELOPING BY EARLY THIS
AFTERNOON. WITH THE HIGH PRESSURE SLOWLY BUILDING TO THE EAST...THE
SMALL CRAFT ADVISORY CONDITION WILL PERSIST FOR THE NEARSHORE
WATERS THROUGH TUESDAY EVENING. THROUGH TUESDAY NIGHT...THE SFC
HIGH WILL BUILD ACROSS THE LAKE...ALLOWING WINDS AND WAVES TO
SUBSIDE. THIS HIGH PRESSURE IS EXPECTED TO PUSH SOUTHEAST OF THE
LAKE BY WEDNESDAY...ALLOWING WINDS TO BRIEFLY TURN
SOUTHWESTERLY...BUT A COLD FRONT DROPPING OUT OF CENTRAL CANADA WILL
QUICKLY TURN THE WINDS BACK NORTHWESTERLY WHILE INCREASING TO AROUND
30KT.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
500 PM CST MON DEC 5 2011
.AVIATION...
FOR THE 00Z TAF ISSUANCE...
PERIODS OF LIGHT SNOW WILL BE POSSIBLE ACROSS CENTRAL AND PORTIONS
OF WESTERN KANSAS TONIGHT...MAINLY SOUTHEAST OF A KHYS TO KDDC LINE.
MVFR CIGS/VSBYS ARE LIKELY IN THE VICINITY OF ALL TAF SITES EARLY
THIS EVENING WITH BRIEF PERIODS OF IFR CIGS POSSIBLE IN THE
VICINITY AND SOUTHEAST OF KDDC THROUGH LATE THIS EVENING. VFR
CONDITIONS WILL GRADUALLY RETURN ACROSS THE AREA LATE TONIGHT AS
THE LOW LEVEL STRATUS MIGRATES EASTWARD THROUGH EARLY TUESDAY
MORNING. SURFACE HIGH PRESSURE WILL PREVAIL ACROSS THE NORTHERN
ROCKIES TONIGHT INFLUENCING NORTHERLY WINDS 5 TO 10KT THROUGH
EARLY TUESDAY MORNING. A LEE SIDE TROUGH OF LOW PRESSURE WILL
DEVELOP ACROSS EASTERN COLORADO TUESDAY MORNING TURNING WINDS
WESTERLY 5 TO 10KT BY EARLY TUESDAY AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 340 PM CST MON DEC 5 2011/
SYNOPSIS...
THE 15.12Z 250 HPA MAP CONTINUED TO SHOW A LARGE TROUGH BISECTING THE
CONUS WITH A STRONG 100 KT JET EXTENDING SOUTHWARD FROM SASKATCHEWAN
AND ACROSS MONTANA. AN EVEN FASTER JET NEAR 150 KT WAS MOVING ACROSS
SE CANADA WITH AN EXTENSION OF THIS JET, ALBEIT WEAKER WINDS, TOWARDS
KANSAS. AT 500 HPA, VERY COLD AIR OF -40 DEG C WAS OBSERVED AT KABR
WITH -30S DEG C SOUTHWARD ACROSS COLORADO. THE ARCTIC AIR AT 700 HPA
WITH TEMPERATURES AT LEAST -20 DEG C EXTENDED ACROSS THE NORTHERN PLAINS.
5 DEGREES OF COOLING WAS NOTED BETWEEN THE 00Z AND 12Z RAOB FOR KDDC
AT 850 HPA. AT THE SURFACE, ARCTIC AIR EXTENDED ACROSS THE PLAINS WITH
TEENS AND 20S DEG F CONTINUING AT 21Z ACROSS THE SUNFLOWER STATE. -SUGDEN
DISCUSSION...
DAYS 1-2...
TONIGHT:
THE VERY SHORT TERM CONCERN FOR THIS EVENING IS THE SNOW POTENTIAL ACROSS
THE CENTRAL AND SOUTHERN HALF OF THE CWFA WITH A MORE APPRECIABLE CHANCE
FOR "HEAVIER" SNOW ACROSS THE SE CWFA. THE SATELLITE WATER VAPOR CHANNEL
SHOWS A WEAK DISTURBANCE MOVING NEW MEXICO AT THE BASE OF AN UPPER LEVEL
TROUGH. A PV ANOMALY ASSOCIATED WITH THE PASSAGE OF THE UPPER LEVEL
TROUGH AND ISENTROPIC LIFT IN THE 290-295K THETA LAYER WILL PROVIDE
ENOUGH LIFT FOR SOME SNOW SHOWERS, PARTICULARLY ACROSS THE SE FA. AS
A RESULT, HAVE INCREASED POPS UP TO CHANCE AND UPPED SNOWFALL AMOUNTS
TO 0.6-1.0 INCHES TOWARDS MEDICINE LODGE. HRRR ALSO IS SHOWING SOME ACCUMULATIONS
WHICH AGREES WITH THE QPF OUTPUT FROM THE THE NAM, GFS, GEM, ECMWF,
ARW, AND NMM...WHICH ALL PAINT A LITTLE QPF IN THIS REGION. OTHERWISE,
MID AND LOW LEVEL CLOUDS WILL EVENTUALLY CLEAR TONIGHT AS THE COLD SURFACE
HIGH PRESSURE CENTER SETTLES ACROSS KANSAS AND THE TROF CONTINUES EAST.
THIS WILL RESULT IN WEAKENING OF WINDS AND ALLOW TEMPERATURES TO PLUMMET.
I HAVE -2 TO -4 DEG F TO THE NORTHWEST AND AROUND 16 DEG F SE AS THE
NW WILL HAVE WEAKER WINDS AND LESS CLOUD COVER THAN COMPARED TO THE
SE. HAVE CONTINUED THE TREND OF HIGHLIGHTING THE LOW WIND CHILL VALUES
IN THE HWO. THESE VALUES ARE NOT EXPECTED TO REACH WIND CHILL ADVISORY
CRITERIA.
TUESDAY:
HAVE ZERO POPS IN TUESDAY AS THE CWFA WILL BE ON THE BACKSIDE (SUBSIDENCE)
OF THE UPPER LEVEL TROUGH AND HIGH PRESSURE WILL CONTINUE AT THE SURFACE.
THINK THE NAM MODEL IS BEING TOO INFLUENCED BY THE SNOWFIELD ACROSS
WEST CENTRAL AND NORTHWEST KANSAS SO HAVE STEERED AWAY FROM THIS RUN.
TEMPERATURES WILL SLIGHTLY MODERATE COMPARED TO MONDAYS HIGHS AND BE
IN THE 20S DEG F. BY TOMORROW EVENING, A WEAK LEE SURFACE TROUGH WILL
DEVELOP ACROSS EASTERN COLORADO WHICH WILL TURN OUR WINDS MORE SOUTHWESTERLY
TO WESTERLY. SKIES SHOULD BE CLEAR WITH A DRY AIRMASS OVERHEAD.
WEDNESDAY:
THE DAY WILL START COLD WITH SINGLE DIGITS TO LOW TEENS DEG F DURING
THE MORNING. DURING THE DAY, THE WEAK LEE SIDE TROUGH WILL MOVE EASTWARDS
ACROSS WESTERN KANSAS USHERED BY A SHORTWAVE TROUGH MOVING ACROSS THE
NORTHERN PLAINS. THIS WILL TURN OUR WINDS MORE NORTHWESTERLY SO WE COULD
SEE SOME DOWNSLOPE CONDITIONS AND RESULT WARMER TEMPERATURES. MEX GUIDANCE
HAS KDDC IN THE 40S AND THE ECMWF IS PARTICULARLY WARM WITH MID 40S
DEG F ACROSS THE CENTRAL AND SE FA. HAVE NOT WARMED TEMPERATURES UP
TO THIS BUT DID TWEAK THEM UP HIGHER WEDNESDAY. -SUGDEN
DAYS 3-7...
A SPLIT JET STREAM IS EXPECTED TO PREVAIL ACROSS THE CONUS WITH BENIGN
WEATHER AS A RESULT THROUGH THE EXTENDED FORECAST.
WEDNESDAY NIGHT THROUGH FRIDAY:
A NORTHWEST TO SOUTHEAST ORIENTED SURFACE HIGH WILL MOVE THROUGH THE
NORTHERN PLAINS THURSDAY AS A SHORTWAVE TROUGH IN THE NORTHERN BRANCH
OF THE JET SWINGS SOUTHEASTWARD AROUND THE SOUTHERN EDGE OF THE LARGER
HUDSON BAY GYRE. ANY NORTHWEST FLOW FRONTOGENESIS AND ATTENDANT SNOW
TIED TO THIS FEATURE WILL BE NORTH AND EAST OF THE SOUTHWEST KANSAS
REGION SO NO POPS ARE IN THE FORECAST. A GLANCING BLOW OF ARCTIC AIR
WILL ONLY RESULT IN A MINIMAL IMPACT ON TEMPERATURES WITH HIGHS GENERALLY
IN THE UPPER 30S FOR BOTH THURSDAY AND FRIDAY.
SATURDAY THROUGH MONDAY:
THE NORTHERN POLAR JET WILL BE SHIFTED NORTH DURING THIS TIME FRAME
WITH VERY WEAK FLOW IN THE MID AND UPPER LEVELS OVER THE CENTRAL ROCKIES
AND GREAT PLAINS. MEANWHILE...THE SOUTHERN JET WILL REMAIN ALONG AN
AXIS FROM THE NORTHERN BAJA OF CALIFORNIA THROUGH SOUTHWEST TEXAS TO
THE GULF COAST REGION. THE DETERMINISTIC GFS AND ECMWF MODELS BOTH
SHOW A MINOR SHORTWAVE TROUGH WITHIN THE SOUTHERN JET MOVING ACROSS
SOUTHERN CALIFORNIA/NORTHERN BAJA CALIFORNIA ENTERING THE DESERT SOUTHWEST
REGION. A JET STREAM IN THE NORTHERN POLAR JET IS EXPECTED TO DIG SOUTHWARD
DOWN THE WEST COAST AROUND SUNDAY...WHICH WILL BECOME INVOLVED WITH
THE SOUTHERN JET IN SOME FASHION. INTERACTION OF SOUTHERN AND NORTHERN
BRANCHES OF THE JET IS SOMETHING THAT MODELS WILL STRUGGLE WITH AT THIS
TIME FRAME...SO THERE IS A LOT OF UNCERTAINTY GOING INTO LATE WEEKEND/EARLY
NEXT WEEK CONCERNING HOW A POTENTIAL MEAN TROUGH IN THE WEST WILL EVOLVE...AND
JUST HOW IT WILL IMPACT SOUTHWEST KANSAS WEATHER AS A RESULT. -UMSCHEID
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 8 27 10 41 / 20 0 0 0
GCK 4 24 8 39 / 10 0 0 0
EHA 6 25 9 41 / 20 0 0 0
LBL 8 27 9 41 / 20 0 0 0
HYS 7 24 9 37 / 10 0 0 0
P28 16 30 14 42 / 40 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FN32/99/99
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
340 PM CST MON DEC 5 2011
.SYNOPSIS...
THE 15.12Z 250 HPA MAP CONTINUED TO SHOW A LARGE TROUGH BISECTING THE
CONUS WITH A STRONG 100 KT JET EXTENDING SOUTHWARD FROM SASKATCHEWAN
AND ACROSS MONTANA. AN EVEN FASTER JET NEAR 150 KT WAS MOVING ACROSS
SE CANADA WITH AN EXTENSION OF THIS JET, ALBEIT WEAKER WINDS, TOWARDS
KANSAS. AT 500 HPA, VERY COLD AIR OF -40 DEG C WAS OBSERVED AT KABR
WITH -30S DEG C SOUTHWARD ACROSS COLORADO. THE ARCTIC AIR AT 700 HPA
WITH TEMPERATURES AT LEAST -20 DEG C EXTENDED ACROSS THE NORTHERN PLAINS.
5 DEGREES OF COOLING WAS NOTED BETWEEN THE 00Z AND 12Z RAOB FOR KDDC
AT 850 HPA. AT THE SURFACE, ARCTIC AIR EXTENDED ACROSS THE PLAINS WITH
TEENS AND 20S DEG F CONTINUING AT 21Z ACROSS THE SUNFLOWER STATE. -SUGDEN
&&
.DISCUSSION...
DAYS 1-2...
TONIGHT:
THE VERY SHORT TERM CONCERN FOR THIS EVENING IS THE SNOW POTENTIAL ACROSS
THE CENTRAL AND SOUTHERN HALF OF THE CWFA WITH A MORE APPRECIABLE CHANCE
FOR "HEAVIER" SNOW ACROSS THE SE CWFA. THE SATELLITE WATER VAPOR CHANNEL
SHOWS A WEAK DISTURBANCE MOVING NEW MEXICO AT THE BASE OF AN UPPER LEVEL
TROUGH. A PV ANOMALY ASSOCIATED WITH THE PASSAGE OF THE UPPER LEVEL
TROUGH AND ISENTROPIC LIFT IN THE 290-295K THETA LAYER WILL PROVIDE
ENOUGH LIFT FOR SOME SNOW SHOWERS, PARTICULARLY ACROSS THE SE FA. AS
A RESULT, HAVE INCREASED POPS UP TO CHANCE AND UPPED SNOWFALL AMOUNTS
TO 0.6-1.0 INCHES TOWARDS MEDICINE LODGE. HRRR ALSO IS SHOWING SOME ACCUMULATIONS
WHICH AGREES WITH THE QPF OUTPUT FROM THE THE NAM, GFS, GEM, ECMWF,
ARW, AND NMM...WHICH ALL PAINT A LITTLE QPF IN THIS REGION. OTHERWISE,
MID AND LOW LEVEL CLOUDS WILL EVENTUALLY CLEAR TONIGHT AS THE COLD SURFACE
HIGH PRESSURE CENTER SETTLES ACROSS KANSAS AND THE TROF CONTINUES EAST.
THIS WILL RESULT IN WEAKENING OF WINDS AND ALLOW TEMPERATURES TO PLUMMET.
I HAVE -2 TO -4 DEG F TO THE NORTHWEST AND AROUND 16 DEG F SE AS THE
NW WILL HAVE WEAKER WINDS AND LESS CLOUD COVER THAN COMPARED TO THE
SE. HAVE CONTINUED THE TREND OF HIGHLIGHTING THE LOW WIND CHILL VALUES
IN THE HWO. THESE VALUES ARE NOT EXPECTED TO REACH WIND CHILL ADVISORY
CRITERIA.
TUESDAY:
HAVE ZERO POPS IN TUESDAY AS THE CWFA WILL BE ON THE BACKSIDE (SUBSIDENCE)
OF THE UPPER LEVEL TROUGH AND HIGH PRESSURE WILL CONTINUE AT THE SURFACE.
THINK THE NAM MODEL IS BEING TOO INFLUENCED BY THE SNOWFIELD ACROSS
WEST CENTRAL AND NORTHWEST KANSAS SO HAVE STEERED AWAY FROM THIS RUN.
TEMPERATURES WILL SLIGHTLY MODERATE COMPARED TO MONDAYS HIGHS AND BE
IN THE 20S DEG F. BY TOMORROW EVENING, A WEAK LEE SURFACE TROUGH WILL
DEVELOP ACROSS EASTERN COLORADO WHICH WILL TURN OUR WINDS MORE SOUTHWESTERLY
TO WESTERLY. SKIES SHOULD BE CLEAR WITH A DRY AIRMASS OVERHEAD.
WEDNESDAY:
THE DAY WILL START COLD WITH SINGLE DIGITS TO LOW TEENS DEG F DURING
THE MORNING. DURING THE DAY, THE WEAK LEE SIDE TROUGH WILL MOVE EASTWARDS
ACROSS WESTERN KANSAS USHERED BY A SHORTWAVE TROUGH MOVING ACROSS THE
NORTHERN PLAINS. THIS WILL TURN OUR WINDS MORE NORTHWESTERLY SO WE COULD
SEE SOME DOWNSLOPE CONDITIONS AND RESULT WARMER TEMPERATURES. MEX GUIDANCE
HAS KDDC IN THE 40S AND THE ECMWF IS PARTICULARLY WARM WITH MID 40S
DEG F ACROSS THE CENTRAL AND SE FA. HAVE NOT WARMED TEMPERATURES UP
TO THIS BUT DID TWEAK THEM UP HIGHER WEDNESDAY. -SUGDEN
DAYS 3-7...
A SPLIT JET STREAM IS EXPECTED TO PREVAIL ACROSS THE CONUS WITH BENIGN
WEATHER AS A RESULT THROUGH THE EXTENDED FORECAST.
WEDNESDAY NIGHT THROUGH FRIDAY:
A NORTHWEST TO SOUTHEAST ORIENTED SURFACE HIGH WILL MOVE THROUGH THE
NORTHERN PLAINS THURSDAY AS A SHORTWAVE TROUGH IN THE NORTHERN BRANCH
OF THE JET SWINGS SOUTHEASTWARD AROUND THE SOUTHERN EDGE OF THE LARGER
HUDSON BAY GYRE. ANY NORTHWEST FLOW FRONTOGENESIS AND ATTENDANT SNOW
TIED TO THIS FEATURE WILL BE NORTH AND EAST OF THE SOUTHWEST KANSAS
REGION SO NO POPS ARE IN THE FORECAST. A GLANCING BLOW OF ARCTIC AIR
WILL ONLY RESULT IN A MINIMAL IMPACT ON TEMPERATURES WITH HIGHS GENERALLY
IN THE UPPER 30S FOR BOTH THURSDAY AND FRIDAY.
SATURDAY THROUGH MONDAY:
THE NORTHERN POLAR JET WILL BE SHIFTED NORTH DURING THIS TIME FRAME
WITH VERY WEAK FLOW IN THE MID AND UPPER LEVELS OVER THE CENTRAL ROCKIES
AND GREAT PLAINS. MEANWHILE...THE SOUTHERN JET WILL REMAIN ALONG AN
AXIS FROM THE NORTHERN BAJA OF CALIFORNIA THROUGH SOUTHWEST TEXAS TO
THE GULF COAST REGION. THE DETERMINISTIC GFS AND ECMWF MODELS BOTH
SHOW A MINOR SHORTWAVE TROUGH WITHIN THE SOUTHERN JET MOVING ACROSS
SOUTHERN CALIFORNIA/NORTHERN BAJA CALIFORNIA ENTERING THE DESERT SOUTHWEST
REGION. A JET STREAM IN THE NORTHERN POLAR JET IS EXPECTED TO DIG SOUTHWARD
DOWN THE WEST COAST AROUND SUNDAY...WHICH WILL BECOME INVOLVED WITH
THE SOUTHERN JET IN SOME FASHION. INTERACTION OF SOUTHERN AND NORTHERN
BRANCHES OF THE JET IS SOMETHING THAT MODELS WILL STRUGGLE WITH AT THIS
TIME FRAME...SO THERE IS A LOT OF UNCERTAINTY GOING INTO LATE WEEKEND/EARLY
NEXT WEEK CONCERNING HOW A POTENTIAL MEAN TROUGH IN THE WEST WILL EVOLVE...AND
JUST HOW IT WILL IMPACT SOUTHWEST KANSAS WEATHER AS A RESULT. -UMSCHEID
&&
.AVIATION...
FOR THE 18Z TAF ISSUANCE...THE MAIN CHALLENGE CONCERNING AVIATION WEATHER
IS HOW LOW CEILINGS WILL GET LATER ON TODAY AND THIS EVENING AS AN UPPER
LEVEL WAVE MOVES ACROSS THE SOUTHERN PLAINS. OBSERVATIONS AS OF 17Z
SHOWED GENERALLY VFR CEILING (AROUND 7-9KFT) ACROSS SOUTHWEST KANSAS...HOWEVER
OVER THE TEXAS PANHANDLE...IFR AND LIFR WERE REPORTED WITH SNOW. THE
SNOW AXIS WILL SHIFT NORTHEAST TONIGHT...BUT IS EXPECTED TO REMAIN SOUTH
OF ALL THREE TERMINALS (DDC, GCK, HYS)...THEREFORE WILL KEEP SNOW OUT
OF THE TERMINALS. WILL BE FORECASTING MVFR CATEGORY BY LATE AFTERNOON...AND
ONLY BRING IN IFR CEILING (900 FOOT) AT DDC CLOSER TO THE SNOW AXIS
AND UPWARD VERTICAL MOTION TIED TO THE STORM SYSTEM. BY LATE TONIGHT/EARLY
TUESDAY MORNING...CEILING WILL GRADUALLY DISSIPATE AND VFR CONDITIONS
WILL RESUME BY 09-12Z TUESDAY TIME FRAME. -UMSCHEID
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 8 27 10 41 / 20 0 0 0
GCK 4 24 8 39 / 10 0 0 0
EHA 6 25 9 41 / 20 0 0 0
LBL 8 27 9 41 / 20 0 0 0
HYS 7 24 9 37 / 10 0 0 0
P28 16 30 14 42 / 40 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FN36/25/25
AREA FORECAST DISCUSSION
NWS GOODLAND KS
221 PM MST MON DEC 5 2011
.DISCUSSION...
221 PM MST MON DEC 5 2011
EARLY AFTERNOON WV IMAGERY AND RUC H5 ANALYSIS SHOW LARGE SCALE
TROUGH EXTENDING FROM GREAT LAKES REGION...ACROSS CENTRAL
COLORADO...WITH BASE OF TROUGH OVER SOUTHERN ARIZONA/NEW MEXICO.
THROUGH TONIGHT...SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD OVER
THE CENTRAL HIGH PLAINS AS A WEAK SHORTWAVE TROUGH CONTINUES TO PUSH
AWAY FROM THE FORECAST AREA. COMBINATION OF CLEARING SKY...VERY
LIGHT WINDS AND WIDESPREAD SNOW COVER WILL CONTRIBUTE TO VERY COLD
TEMPERATURES OVERNIGHT. AMBIENT TEMPERATURES WILL FALL BELOW ZERO
FOR ALL BUT THE FAR SOUTHEAST PORTION OF THE FORECAST AREA WHICH
WILL REMAIN AT OR SLIGHTLY ABOVE ZERO. DESPITE THE LIGHT
WINDS...WIND CHILL READINGS WILL FALL TO AS LOW AS 20 BELOW ZERO FOR
A PERIOD OF TIME PRIMARILY OVER THE NORTHWEST HALF OF THE FORECAST
AREA. AS SUCH...WILL ISSUE A WIND CHILL ADVISORY.
FOLTZ
TUESDAY-WEDNESDAY...SHORTWAVE RIDGING WILL BUILD OVER THE CWA
TUESDAY QUICKLY FOLLOWED BY WESTERLY FLOW ALOFT WEDNESDAY...WHICH
WILL FAVOR DRY CONDITIONS OVER CWA. SHALLOW COLD AIR MASS WILL BEGIN
TO MODERATE...WITH HIGH/LOW TEMP FORECAST COMPLICATED BY LINGERING
SNOW PACK. CONTINUED TO UNDERCUT GUIDANCE THROUGH THESE
PERIODS....NOT EXPECTING TEMPS TO MAKE IT ABOVE FREEZING UNTIL
WED AFTERNOON.
WEDNESDAY NIGHT-THURSDAY NIGHT...COLD FRONT PUSHES SOUTH ACROSS CWA
WEDNESDAY NIGHT...WITH SHORTWAVE TROUGH PASSING NORTH OF CWA
THURSDAY/THURSDAY NIGHT. BEST LIFT/MOISTURE LOOKS TO REMAIN OVER
CENTRAL NEBRASKA...HOWEVER MODEL POINT SOUNDINGS DO SHOW DENDRITIC
LAYER BEGINNING TO SATURATE IN EXTREME NORTHERN PART OF CWA IN THE
21Z-00Z TIME FRAME. WENT AHEAD AND ADDED SLIGHT CHANCE POPS TO SW
NEBRASKA COUNTIES 18Z-00Z WHERE A DUSTING COULDNT BE RULED OUT. ALSO
EXPANDED FLURRIES FURTHER SOUTH...AND MADE CONDITIONS DRY AFTER 06Z.
FRIDAY-MONDAY...WARMING TREND WILL START UP AGAIN FRIDAY...AND
CONTINUE THROUGH THE WEEKEND WITH SHORTWAVE RIDGING ACROSS WESTERN
CONUS THROUGH SATURDAY. TEMPERATURES SHOULD MODERATE TO NEAR
NORMAL VALUES IN THE UPPER 30S/LOW 40S SAT/SUN. CLOSED LOW BEGINS
TO DEVELOP OVER SW CONUS BY SUNDAY NIGHT/MONDAY WITH W/SW FLOW
DEVELOPING OVER CWA AHEAD OF THIS FEATURE. GUIDANCE IN GENERAL
AGREEMENT ON ARRIVAL OF COLD FRONT SUN NIGHT/MON...WHICH SHOULD
SUPPORT A RETURN TO BELOW NORMAL TEMPERATURES EARLY NEXT WEEK. NOT
EXPECTING ANY PRECIP THROUGH EXTENDED PERIODS...WITH DRY AIR MASS
IN PLACE OVER CWA.
DR
&&
.AVIATION...
1016 AM MST MON DEC 5 2011
FOR THE 18Z TAFS...MAIN CONCERN FOR THE PREVAILING PERIOD WILL BE
THE POSSIBILITY OF FOG/BR DEVELOPING OVERNIGHT AT BOTH TERMINALS.
TEMPERATURES WILL REMAIN COLD TODAY WHICH WILL LIMIT MELTING...
AND MAY AFFECT FOG FORMATION. HAVE DECIDED TO GO AHEAD AND INCLUDE
A PERIOD OF MVFR...WITH THE CHANCE OF REACHING IFR OR LIFR IF FOG
DEVELOPS. OTHERWISE...SURFACE HIGH PRESSURE ACROSS THE AREA WILL
KEEP WINDS LIGHT WITH CLEARING SKIES OVERNIGHT. A FEW FLURRIES AND
SOME SCATTER LOW LEVEL CLOUDS MAY BE POSSIBLE THIS AFTERNOON GIVEN
REGIONAL OBS...BUT IMPACTS WILL BE MINIMAL TO NONE.
PMM
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...WIND CHILL ADVISORY FROM 11 PM MST /MIDNIGHT CST/ THIS EVENING
TO 8 AM MST /9 AM CST/ TUESDAY FOR KSZ001>003-013-014-027.
NE...WIND CHILL ADVISORY FROM 11 PM MST /MIDNIGHT CST/ THIS EVENING
TO 8 AM MST /9 AM CST/ TUESDAY FOR NEZ079>081.
CO...WIND CHILL ADVISORY FROM 11 PM THIS EVENING TO 8 AM MST TUESDAY
FOR COZ090>092.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
456 AM MST MON DEC 5 2011
.DISCUSSION...
347 AM MST MON DEC 5 2011
MAIN FORECAST PROBLEM WILL BE A PROBLEMATIC TEMPERATURE FORECAST
THROUGH THE SHORT TERM. SATELLITE SHOWING AN AMPLIFIED AND
RETROGRESSIVE FLOW FROM THE PACIFIC INTO CENTRAL NORTH AMERICA.
AMPLIFIED UPPER RIDGE SLOWING MOVING WEST AS TROUGH THAT EXTENDS FROM
EASTERN CANADA INTO THE SOUTHWEST PORTION OF THE COUNTRY CONTINUES TO
SAG TO THE SOUTH AND WEST. VERY COLD AIR MASS IN PLACE WITH COLDER
AIR POISED TO COME FURTHER SOUTH.
AT JET LEVEL THE MODELS INITIALIZED FINE. AT MID LEVELS...THE UKMET
INITIALIZED A LITTLE BETTER...ESPECIALLY WITH THE NORTHERN END OF
THE TROUGH. THE MODELS TENDED TO HAVE THE SURFACE RIDGING TOO FAR
SOUTH AND EAST. THE NAM FOLLOWED BY THE ECMWF WAS DOING A LITTLE
BETTER HERE. WITH THE LOW LEVEL THERMAL FIELD...THE GFS WAS DOING
SLIGHTLY BETTER THAN THE OTHER GUIDANCE.
TODAY/TONIGHT...WAS HARD TO TELL THE EXACT EXTENT OF THE SNOW FIELD
DUE TO CLOUD COVER OVER THE AREA. THAT AND CLOUD COVER THROUGH
TONIGHT WILL BE THE MAIN PLAYERS IN WHAT THE TEMPERATURES WILL DO.
DEFINITELY LOOKS LIKE A LOT OF CLOUDS AROUND THROUGH THE DAY. THAT
COMPLICATED BY THE SNOW COVER...WILL MAKE FOR A COLD DAY. BASED ON
LATEST TRENDS AND MODEL DATA...DECIDED TO LOWER MAXES A FEW
DEGREES.
UPPER AIR ANALYSIS SHOWS EXTREMELY COLD AIR UPSTREAM AT MID LEVELS.
LOOKING AT THE 700 TO 500 MB ANALYSIS...IT WOULD APPEAR THAT THERE
SHOULD BE VERY GOOD LAPSE RATES BUT MODELS REALLY DO NOT SHOW
THAT. UPSTREAM SOUNDINGS WOULD INDICATE MOST IF NOT THE ENTIRE
SOUNDING IS -10 C OR COLDER/IN THE DENDRITIC ZONE. MODELS INDICATE
SOME KIND OF LIFT ALBEIT NOT THAT STRONG THROUGH THE DAY...
ESPECIALLY IN THE SOUTH. MOISTURE IS SHALLOW. HOWEVER...AM THINKING
WITH SUCH A COLD AIR MASS IN PLACE...WOULD NOT TAKE MUCH TO PRODUCE
SOME FLURRIES. SO AT THIS TIME...INSERTED FLURRIES INTO THE SOUTHERN
PORTION OF THE AREA THROUGH EARLY EVENING.
HUGE DIFFERENCE TONIGHT IN WHAT THE MODELS THINK THE CLOUDS
AND RESULTING TEMPERATURE FORECAST WILL BE. NAM BELIEVES THERE WILL
BE A LOT OF CLOUDS AROUND WHILE THE OTHER MODELS CLEAR IT OUT. THE
SOUTHERN PORTION OF THE AREA WILL CLEAR OUT THE LAST AND WILL HAVE
THE LEAST COLD MINS. AT THIS TIME BELIEVE THAT THE COLDER/LEAST CLOUD
COVER WILL OCCUR. HOWEVER...ENOUGH UNCERTAINTY FOR ME TO NOT GO FOR
IT. TENDED TO SPLIT THE DIFFERENCE BUT WENT SLIGHTLY TOWARD THE
COLDER GUIDANCE. WINDS WILL BE LESS THAN 10 MPH MOST AREAS.
HOWEVER...IF THE COLDEST...MUCH BELOW ZERO MINS...ARE REALIZED...WIND
CHILL ADVISORY CRITERIA COULD BE REACHED. WILL BRIEF IN THE NEXT
SHIFT AND HIGHLIGHT THIS IN THE HWO.
TUESDAY/TUESDAY NIGHT...LOW WIND CHILLS WILL OCCUR EARLY IN THE
MORNING. DESPITE THE GENERAL TENDENCY OF THE MODELS TO HAVE A
NORTHEAST TO SOUTHWEST JET AXIS THAT BEGINS TO MOVE ACROSS THE AREA
FROM LATE MORNING THROUGH AT LEAST THE EVENING HOURS...THERE IS A
BIG MODEL DIFFERENCE IN HOW TO HANDLE THE JET AND THE RESULTING
UPPER TROUGH THAT IS MOVING EAST AND SOUTH OF THE AREA. FOR THE EASY
PART IT LOOKS LIKE A LOT MORE SUN AT THIS TIME. HOWEVER...WOULD
STILL EXPECT THE SNOW FIELD TO HAVE CHANGED LITTLE DUE TO THE LACK
OF SUNSHINE DURING THE PREVIOUS TWO DAYS AND COOLING SOIL
TEMPERATURES. OF COURSE A MAJOR CONTRIBUTOR TO THIS IS HOW COLD THE
DAY STARTS.
IN ADDITION MORE OF THE DETERMINISTIC MODEL OUTPUT WITH ENSEMBLE
SUPPORT IS WANTING TO CUT OFF A LOW ON THE SOUTHERN END OF THIS
TROUGH NOT TOO FAR AWAY FROM THE AREA...WITH THE LAST TWO RUNS OF THE
NAM...LATEST SREF...AND NOW EVEN MORESO THE 06Z GFS THE MOST
AGGRESSIVE WITH THIS. ALL THINGS CONSIDERED...THE MODELS OVERALL LOOK
TOO WARM WITH THE EXCEPTIONS OF THE CANADIAN AND NAM. TRENDED TOWARD
THE COOLER SIDE OF GUIDANCE BUT THIS COULD CHANGE.
WEDNESDAY/WEDNESDAY NIGHT...MAIN JET AXIS LOOKS TO STAY NORTH AND
EAST OF THE AREA THROUGH THE PERIOD. ABOVE DISCUSSION ON BEHAVIOR
OF THE UPPER TROUGH WILL HAVE A SIGNIFICANT IMPACT ALONG WITH THE
SNOW COVER ON THE HIGH TEMPERATURES. THE COOLER GUIDANCE SUPPORTED
THE CURRENT FORECAST AND DID NOT CHANGE. BUT AGAIN CONFIDENCE IS
LOW.
THANKS TO ALL THAT COLLABORATED.
BULLER
THURSDAY THROUGH SUNDAY...THROUGH THE PERIOD AN UPPER LEVEL TROUGH
WILL REMAIN OVER EASTERN CANADA...WITH THE UPPER LEVEL RIDGE
CURRENTLY OVER THE PACIFIC BUILDING OVER THE CONUS THROUGH SATURDAY.
THURSDAY A COLD FRONT WILL MOVE THROUGH THE HIGH PLAINS. MODELS
DISAGREE WITH THE TIMING OF THE PASSAGE...WITH IT EITHER MOVING
THROUGH DURING THE EARLY MORNING OR OVERNIGHT. BEHIND THE FRONT AN
UPPER LEVEL TROUGH WILL MOVE THROUGH THURSDAY NIGHT. MODELS ARE IN
GOOD AGREEMENT WITH PLACEMENT AND SPEED OF THE TROUGH. BETTER
FORCING LOOKS TO BE NORTH OF THE CWA...SO WILL KEEP THE FORECAST DRY
THURSDAY AS THE FRONT AND TROUGH PASS THROUGH. HOWEVER A FEW
FLURRIES MAY BE POSSIBLE IN THE EAST AS SOME FORCING WILL BE PRESENT
AS THE TROUGH MOVES THROUGH OVERNIGHT. FRIDAY THE UPPER LEVEL RIDGE
BEGINS TO BUILD OVER THE REGION WITH A SPLIT FLOW PATTERN DEVELOPING.
BY SUNDAY THE RIDGE FLATTENS OUT OVER THE CENTRAL PLAINS. MEANWHILE
AN UPPER LEVEL TROUGH MOVES DOWN FROM CANADA ALONG THE WEST COAST.
AS THE TROUGH MOVES SOUTH THE UPPER LEVEL FLOW BEGINS TO MERGE ONCE
AGAIN...WHICH MAY GIVE THE REGION A SHOT AT PRECIPITATION NEXT WEEK.
TEMPERATURES THROUGH THE PERIOD WILL WARM AS THE UPPER LEVEL RIDGE
BUILDS IN. HOWEVER THE WARM UP WILL DEPEND ON HOW MUCH SNOW IS
PRESENT. CURRENT BLEND OF PREVIOUS FORECAST AND LATEST MODELS HAVE
VALUES BELOW MOST GUIDANCE SO WILL LEAVE TEMPS AS THEY ARE. HIGHS
WILL BE AS MUCH AS 10 DEGREES BELOW NORMAL WITH LOWS NEAR TO A FEW
DEGREES BELOW NORMAL.
JTL
&&
.AVIATION...
426 AM MST MON DEC 5 2011
VFR TO MVFR CONDITIONS WILL BE POSSIBLE FOR THE 12Z TAFS. CURRENT
SATELLITE AND OBS SHOW LOW CLOUDS AND PRECIP OVER COLORADO SOUTH
INTO THE TEXAS PANHANDLE. SOUNDINGS SHOW THE LOW CLOUDS MAKING
THEIR WAY TO THE TAF SITES THROUGH EARLY AFTERNOON. SREF SHOWS A GOOD
POSSIBILITY OF IFR CEILINGS DURING THE AFTERNOON FOR KGLD. HOWEVER
MOS AND NAM DO NOT...ALTHOUGH THE HRRR DOES SHOW A SMALL AREA OF
IFR CEILINGS NEAR GLD FOR A COUPLE HOURS DURING THE AFTERNOON. AM
NOT CONFIDENT ENOUGH TO PLACE IFR CEILINGS IN...BUT WILL ADJUST
THE MVFR CEILINGS TO BEGIN SOONER FOLLOWING GUIDANCE. FOR KMCK LOW
CEILINGS LOOK TO REMAIN JUST EAST AND SOUTH OF THE SITE UNTIL LATE
MORNING BEFORE DROPPING DURING THE AFTERNOON. CEILINGS FOR THE TAF
SITES LOOK TO REMAIN MVFR THROUGH MOST OF THE NIGHT BEFORE LIFTING
TUESDAY MORNING. FOR KGLD THERE COULD BE SOME VIS REDUCTIONS
OVERNIGHT AS TEMPERATURES PLUMMET. WILL ONLY CARRY A SLIGHT
REDUCTION FOR NOW.
JTL
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CARIBOU ME
253 PM EST MON DEC 5 2011
.SYNOPSIS...
A SLOW MOVING COLD FRONT WILL APPROACH NORTHERN MAINE THIS
EVENING AND THEN MOVE ACROSS THE STATE BY LATE TONIGHT. THE FRONT
WILL MOVE OFF THE COAST LATER TUESDAY WITH A SERIES OF WEAK LOW
PRESSURES TRACKING ALONG THE COASTAL FRONT TUESDAY NIGHT INTO
WEDNESDAY.
&&
.NEAR TERM /THROUGH TUESDAY/...
FIRST SURGE OF RAIN HAS MOVED OUT OF NORTHERN MAINE EARLY THIS
AFTERNOON AS DEPICTED BY THE HRRR MODEL. THE HRRR MODEL DOES NOT
BRING THE NEXT SURGE BACK INTO NORTHERN MAINE UNTIL EARLY THIS
EVENING SO WILL START OUT WITH LOWER POPS ACROSS THE NORTH AND
THEN GRADUALLY INCREASE POPS BACK TO CATEGORICAL THIS EVENING. AS
THE COLD FRONT CROSSES NORTHERN MAINE AFTER MIDNIGHT, RAIN WILL
MIX WITH SNOW AND THEN CHANGE TO ALL SNOW ACROSS MAINLY NORTHERN
AROOSTOOK COUNTY. SNOW WILL CONTINUE INTO THE MORNING HOURS BUT
EXPECT SNOW TO BE LIGHT. AT THIS TIME STILL EXPECTING 1 TO 3
INCHES OF SNOW ACROSS NORTHERN SECTIONS WITH THE HIGHEST VALUES
ACROSS THE ST. JOHN VALLEY.
EXPECT RAIN TO MOVE INTO CENTRAL REGIONS AFTER MIDNIGHT AND THEN
INTO DOWNEAST JUST BEFORE SUNRISE TUESDAY. RAIN WILL CONTINUE FOR
MOST OF THE DAY OVER DOWNEAST AS LOW PRESSURE MOVES ALONG THE
FRONT AS IT SLIDES OFF THE COAST.
HIGH TEMPERATURES ON TUESDAY WILL ONLY RISE 1 TO 3 DEGREES FROM
THE MORNING LOWS AS COLDER AIR MOVES IN WITH THE NORTH WINDS
BEHIND THE COLD FRONT.
FOR RAINFALL AMOUNTS EXPECTING BETWEEN A QUARTER TO HALF AN INCH
ACROSS THE REGION BY TUESDAY AFTERNOON.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
THE UNSETTLED PATTERN WILL CONTINUE THROUGH THE SHORT TERM. A COLD
FRONT WILL BE STRETCHED ACROSS THE GULF OF MAINE TUESDAY NIGHT WITH
A WAVE OF LOW PRESSURE POSITIONED NEAR NOVA SCOTIA TUESDAY EVENING.
PRECIPITATION...MOSTLY IN THE FORM OF SNOW THOUGH MIXED WITH RAIN
DOWNEAST AND ESPECIALLY ALONG THE COAST... WILL BEGIN TO WIND DOWN
OVERNIGHT AS THIS LOW CONTINUES TO TREK TO THE EAST. HOWEVER ANOTHER
WEAK WAVE...THIS ONE FURTHER SOUTH...WILL KEEP AT LEAST THE SLIGHT
CHANCE OF RAIN/SNOW SHOWERS ACROSS THE REGION THROUGH WEDNESDAY
MORNING. HIGH PRESSURE WILL FINALLY BE ABLE TO TAKE HOLD WEDNESDAY
NIGHT...BUT YET ANOTHER LOW WILL MOVE TO THE SOUTH OF THE GULF OF
MAINE THURSDAY. THE 12Z ECMWF IS THE MOST AGGRESSIVE AND THE
FURTHEST NORTH WITH THIS SYSTEM AND INDICATES THAT MUCH OF DOWNEAST
MAINE WOULD SEE A RAIN/SNOW MIX. THE 12Z NAM AND GFS MEANWHILE KEEP
THE LOW SOUTH AND ONLY BRUSH THE COAST WITH PRECIPITATION. HAVE GONE
WITH SLIGHT CHANCE POPS FOR NOW. ALSO KEPT SLIGHT CHANCE POPS ACROSS
THE NORTH AS A COLD FRONT APPROACHES FROM CANADA. DAYTIME
TEMPERATURES WEDNESDAY AND THURSDAY WILL RANGE FROM THE LOWER 30S
NORTH TO AROUND 40 SOUTH WHILE THE NIGHTS DIP DOWN INTO THE 20S.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
THE START OF THE LONG TERM FINDS THE GFS AND THE ECMWF WITH A
SIMILAR SOLUTION...HOWEVER THE GFS APPEARS ABOUT 6HRS BEHIND THE
ECMWF ON MOVEMENT OF THE MAIN LOW. A LOW PRESSURE (GFS) IN THE N
ATLANTIC SE OF NOVA SCOTIA...A DEEP COLD CORE LOW OVER HUDSON BAY
WITH A TROUGH EXTENDING S THROUGH THE CENTRAL GREAT LAKES REGION.
A CANADIAN HIGH PRESSURE RIDGE THAT DUG INTO THE SOUTHERN STATES
WILL BEGIN TO SPREAD TOWARDS NEW ENGLAND. THE ECMWF THE PRIMARY
LOW IS FARTHER NORTH INTO THE CANADIAN MARITIMES. AND THE BUILDING
RIDGE EXTEND FARTHER NORTH INTO SOUTHERN NEW ENGLAND. BY FRIDAY
MORNING THE HIGH MOVES INTO THE ATLANTIC... THE GFS DIGS THE
TROUGH ACROSS THE GREAT LAKE FARTHER SOUTH. THE ECMWF DEVELOPS A
WEAK LOW OVER EASTERN ILLINOIS. BY FRIDAY EVENING BOTH MODELS ARE
INDICATING A LOW OVER THE NORTHERN GREAT LAKES...WITH A TROUGH OF
LOWER PRESSURE EXTENDING SOUTH ALONG THE EASTERN SEABOARD. BY
EARLY SATURDAY MORNING BOTH MODELS MOVES THE LOW EAST...THE GFS TO
NRN MAINE...THE ECMWF TO SRN QUEBEC. BY SATURDAY MORNING THE GFS
MOVES THE LOW AND FRONT EAST OF THE AREA...THE ECMWF TO ERN MAINE.
BY SATURDAY EVENING THE LOW WILL BE WELL EAST AND A HIGH PRESSURE
RIDGE WILL BUILD IN. HIGHER PRESSURE WILL BUILD IN THROUGH THE END
OF THE PERIOD...HOWEVER THE COLD LOW OVER HUDSON BAY WILL REMAIN
THROUGH THE PERIOD AND WILL PERIODICALLY KICK OFF SHORT WAVES THAT
WILL MOVE THROUGH NORTHERN AND CENTRAL MAINE THROUGH THE END OF
THE PERIOD.
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 /19Z MONDAY THROUGH SATURDAY/...
NEAR TERM: VFR CONDITIONS ACROSS THE NORTH WILL LOWER TO MVFR THIS
EVENING AND THEN IFR BY LATER TONIGHT AND REMAIN IFR THROUGH
TUESDAY. VFR CONDITIONS ACROSS DOWNEAST WILL LOWER TO IFR AFTER
SUNRISE TUESDAY AND REMAIN IFR FOR THE REMAINDER OF THE DAY.
SHORT TERM: WIDESPREAD IFR IN SNOW /MIXED WITH RAIN SOUTH/
EXPECTED INTO WEDNESDAY MORNING...THEN GRADUALLY IMPROVING
CONDITIONS FROM NORTH TO SOUTH WEDNESDAY AFTERNOON AS HIGH
PRESSURE BUILDS OVER THE REGION. CLOUDS WILL INCREASE LATE
WEDNESDAY NIGHT AND THURSDAY AS A COLD FRONT APPROACHES FROM
CANADA AND A LOW PRESSURE SYSTEM MOVES TO THE SOUTH OF THE GULF OF
MAINE. THERE IS A SLIGHT CHANCE THAT THESE SYSTEMS WILL BRING SNOW
AND MVFR/IFR CONDITIONS TO THE REGION THURSDAY. MORE RAIN/SNOW IS
POSSIBLE FRIDAY AND FRIDAY NIGHT AS ANOTHER LOW MOVES ACROSS
NORTHERN MAINE.
&&
.MARINE...
NEAR TERM: WINDS AND SEAS WILL REMAIN BELOW SCA CRITERIA THROUGH
TUESDAY. A COLD FRONT WILL APPROACH FROM THE NORTH TONIGHT AND
TUESDAY AND THEN CROSS THE WATERS BY TUESDAY EVENING.
SHORT TERM: NO HEADLINES EXPECTED OVER THE WATERS AS WINDS REMAIN
BELOW 25 KT AND WAVES LESS THAN 5 FT. THE WEATHER WILL BE
UNSETTLED HOWEVER AS A SERIES OF LOW PRESSURE WAVES MOVE OVER OR
JUST TO THE SOUTH OF THE GULF OF MAINE THROUGH MID WEEK.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...FOSTER
SHORT TERM...HASTINGS
LONG TERM...NORTON
AVIATION...FOSTER
MARINE...FOSTER/HASTINGS
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
116 AM EST MON DEC 5 2011
.SYNOPSIS...
HIGH PRESSURE DOMINATES THE MID ATLANTIC REGION TODAY. A COLD FRONT
MOVES INTO THE REGION FROM THE WEST LATE TUESDAY. LOW PRESSURE
RIDES NORTHWARD ALONG THE FRONT WEDNESDAY INTO THURSDAY. HIGH
PRESSURE RETURNS LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS HIGH PRESSURE MOVES SLOWLY OFF THE COAST...LIGHT WINDS ARE
BECOMING SOUTHEAST AND SOUTH...BRINGING INCREASING MOISTURE TO THE
AREA. AS OF 05Z...AREAS OF FOG COVERED THE EASTERN SHORE AND
PORTIONS OF COASTAL SOUTHEAST VIRGINIA AND NORTHEAST NORTH
CAROLINA. SOME AREAS HAVE VISIBILITY UNDER ONE HALF MILE. INLAND
AREAS...THE FOG HAS BEEN INTERMITTENT. RUC AND NAM CONTINUE TO
INDICATE FOG DEVELOPING ACROSS THE CWA...MOST WIDESPREAD EAST OF
I95. SPS ISSUED FOR THE LOWER EASTERN SHORE AND VA EAST OF I95.
NO SIGNIFICANT CHANGE TO THE LOW TEMPERATURES WHICH ARE EXPECTED
TO RANGE FROM THE UPR 30S AND LOWER 40S WEST OF I95 AND THE 40S TO
NEAR 50 ALONG THE COAST.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY/...
THE UPR RIDGE JUST OFFSHORE WILL GRADUALLY GET SHOVED EASTWARD
THROUGH TUESDAY IN RESPONSE TO A BROAD UPPER TROUGH DIGGING INTO
THE CENTER OF THE NATION. BY LATE TUESDAY...THE UPR TROUGH WILL
PUSH A COLD FRONT TOWARD THE MID-ATLANTIC REGION WITH THIS
FEATURE SAGGING SOUTHWARD THROUGH VA AND INTO NE NC BY 12Z WED. AS
THE UPR TROUGH CONTINUES TO DIG AND A CUTOFF LOW DEVELOPS OVER THE
SOUTHERN PLAINS/LOWER MS VALLEY ON WED...THE FRONT WILL STALL OUT
ACROSS THE CAROLINAS WITH SFC LOW PRESSURE DEVELOPING ALONG IT.
UNFORTUNATELY...CONFIDENCE IN THE FORECAST BY WEDNESDAY IS LOW
GIVEN THE LARGE SPREAD IN THE MODELS AT THAT TIME...SO HAVE NOT
GONE HIGHER THAN 50% POP FOR TUESDAY NIGHT AND WEDNESDAY. IN THE
MEANTIME...MOISTURE WILL CONTINUE TO INCREASE FROM MONDAY INTO
TUESDAY ALLOWING FOR MOSTLY CLOUDY CONDITIONS. WILL KEEP DRY WX IN
THE FORECAST THROUGH MONDAY EVENING...BEFORE ADDING LOW CHC POPS
INTO WESTERN AREAS BY EARLY TUESDAY MORNING. AS THE FRONT NEARS ON
TUESDAY...WILL SEE CHC POPS (30-40%) SPREAD EASTWARD. HIGHEST POPS
(~50%) AGAIN WILL BE TUESDAY NIGHT/WEDNESDAY AS THE FRONT STALLS
JUST SOUTH OF OUR CWA. HIGHS MONDAY/TUESDAY IN THE 60S...EXCEPT
AROUND 70 IN THE VA TIDEWATER/NE NC. WEDNESDAY`S HIGHS WILL DEPEND
OF PCPN COVERAGE BUT SHOULD BE IN THE MID 50S NW TO THE LOW 60S SE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
LO CONFIDENCE FCST MIDWEEK...HV CHOSEN TO GO CLSR TO COMBO OF
SREF/ECMWF SOLN WRT FNT PLCMNT AND EVENTUAL SFC LO PRES DVLPMNT/MVG
WED NGT INTO THU. THAT WOULD HV MNLY N WNDS...AND WDSPRD CVRG OF RA
(FOR NOW CAPPING POPS AT 50% OVR MOST OF THE FA). LO PRES XPCTD TO
MV OUT TO SEA THU NGT...W/ DRYING/SEASONABLY COLD WX FM FRI THROUGH
NEXT WKND. ACCOMPANYING THE ARRIVAL OF THE COLD AIR WL BE GUSTY NW
WNDS THU NGT INTO FRI.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
IFR/LIFR CONDITIONS WILL PREVAIL THROUGH THE OVERNIGHT ACROSS ERN
VA AND NERN NC...WITH THE WEAK SE (ONSHORE) FLOW AND THUS MSTR
ADVECTION INTO THE SFC-1000 MB LAYER. THE FOG HAS BEGUN TO LIFT
OVER THE PAST FEW HOURS OVER NERN NC...COINCIDING WITH AN
EXPANDING STRATO-CU DECK OFF THE OCEAN (BASES 5-7KFT). OVER TIME
AS THE STRAO-CU DECK SPREADS SLOLY NORTHWARD ON THE BACKSIDE OF
THE SFC HIGH...EXPECT THE TREND OF IMPROVING VSBYS TO CONTINUE
FARTHER NORTH (TO INCLUDE KORF/KPHF BY 8-10Z)...GIVEN THE
WEAKENING RADIATIONAL COOLING COMPONENT.
CONDITIONS WILL BE SLOWER TO IMPROVE OVER THE LOWER ERN SHORE...
WHERE THE FOG/STRATUS IS EXPECTED TO HANG ON UNTIL 14-16Z.
OUTLOOK...THE NEXT CHANCE FOR RAIN COMES MID-WEEK WITH THE
APPROACH OF A SLOW MOVING COLD FRONT.
&&
.MARINE...
SFC HI PRES OFFSHR RMNS IN CONTROL OVR THE WTRS THROUGH ERY PART OF
THE WK. SE TO S WNDS AOB 10 KT XPCTD THROUGH MON...W/ GRDL INCRS IN
SPDS MON NGT INTO TUE. SLO MVG CDFNT APPROACHES FM THE WNW TUE/TUE
NGT...THEN XPCTD TO SETTLE OVR THE WTRS WED. GOING CLSR TO
SREF/ECMWF SOLN W/ EVENTUALLY PUSH SWD OF FNTL BNDRY ON WED. WL HV
WNDS BCM MNLY N OVR THE FA ON WED AS FNTL SETTLES INTO FA.
TRACK/INSTENSITY OF SFC LO PRES ALG THE FNT LT WED INTO THU STILL
PROBLEMATIC ATTM. MOD/STRNG NW WNDS XPCTD BEHIND DEPARTING LO
PRES LT THU INTO FRI. NO HEADLINES NEEDED THROUGH MON NGT/TUE.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDM
NEAR TERM...MAM/LSA/MAS
SHORT TERM...JDM
LONG TERM...ALB
AVIATION...JEF/LSA
MARINE...BKH
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1231 AM EST MON DEC 5 2011
.SYNOPSIS...
HIGH PRESSURE DOMINATES THE MID ATLANTIC REGION TODAY. A COLD FRONT
MOVES INTO THE REGION FROM THE WEST LATE TUESDAY. LOW PRESSURE
RIDES NORTHWARD ALONG THE FRONT WEDNESDAY INTO THURSDAY. HIGH
PRESSURE RETURNS LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS HIGH PRESSURE MOVES SLOWLY OFF THE COAST...LIGHT WINDS ARE
BECOMING SOUTHEAST AND SOUTH...BRINGING INCREASING MOISTURE TO THE
AREA. AS OF 05Z...AREAS OF FOG COVERED THE EASTERN SHORE AND
PORTIONS OF COASTAL SOUTHEAST VIRGINIA AND NORTHEAST NORTH
CAROLINA. SOME AREAS HAVE VISIBILITY UNDER ONE HALF MILE. INLAND
AREAS...THE FOG HAS BEEN INTERMITTENT. RUC AND NAM CONTINUE TO
INDICATE FOG DEVELOPING ACROSS THE CWA...MOST WIDESPREAD EAST OF
I95. SPS ISSUED FOR THE LOWER EASTERN SHORE AND VA EAST OF I95.
NO SIGNIFICANT CHANGE TO THE LOW TEMPERATURES WHICH ARE EXPECTED
TO RANGE FROM THE UPR 30S AND LOWER 40S WEST OF I95 AND THE 40S TO
NEAR 50 ALONG THE COAST.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY/...
THE UPR RIDGE JUST OFFSHORE WILL GRADUALLY GET SHOVED EASTWARD
THROUGH TUESDAY IN RESPONSE TO A BROAD UPPER TROUGH DIGGING INTO
THE CENTER OF THE NATION. BY LATE TUESDAY...THE UPR TROUGH WILL
PUSH A COLD FRONT TOWARD THE MID-ATLANTIC REGION WITH THIS
FEATURE SAGGING SOUTHWARD THROUGH VA AND INTO NE NC BY 12Z WED. AS
THE UPR TROUGH CONTINUES TO DIG AND A CUTOFF LOW DEVELOPS OVER THE
SOUTHERN PLAINS/LOWER MS VALLEY ON WED...THE FRONT WILL STALL OUT
ACROSS THE CAROLINAS WITH SFC LOW PRESSURE DEVELOPING ALONG IT.
UNFORTUNATELY...CONFIDENCE IN THE FORECAST BY WEDNESDAY IS LOW
GIVEN THE LARGE SPREAD IN THE MODELS AT THAT TIME...SO HAVE NOT
GONE HIGHER THAN 50% POP FOR TUESDAY NIGHT AND WEDNESDAY. IN THE
MEANTIME...MOISTURE WILL CONTINUE TO INCREASE FROM MONDAY INTO
TUESDAY ALLOWING FOR MOSTLY CLOUDY CONDITIONS. WILL KEEP DRY WX IN
THE FORECAST THROUGH MONDAY EVENING...BEFORE ADDING LOW CHC POPS
INTO WESTERN AREAS BY EARLY TUESDAY MORNING. AS THE FRONT NEARS ON
TUESDAY...WILL SEE CHC POPS (30-40%) SPREAD EASTWARD. HIGHEST POPS
(~50%) AGAIN WILL BE TUESDAY NIGHT/WEDNESDAY AS THE FRONT STALLS
JUST SOUTH OF OUR CWA. HIGHS MONDAY/TUESDAY IN THE 60S...EXCEPT
AROUND 70 IN THE VA TIDEWATER/NE NC. WEDNESDAY`S HIGHS WILL DEPEND
OF PCPN COVERAGE BUT SHOULD BE IN THE MID 50S NW TO THE LOW 60S SE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
LO CONFIDENCE FCST MIDWEEK...HV CHOSEN TO GO CLSR TO COMBO OF
SREF/ECMWF SOLN WRT FNT PLCMNT AND EVENTUAL SFC LO PRES DVLPMNT/MVG
WED NGT INTO THU. THAT WOULD HV MNLY N WNDS...AND WDSPRD CVRG OF RA
(FOR NOW CAPPING POPS AT 50% OVR MOST OF THE FA). LO PRES XPCTD TO
MV OUT TO SEA THU NGT...W/ DRYING/SEASONABLY COLD WX FM FRI THROUGH
NEXT WKND. ACCOMPANYING THE ARRIVAL OF THE COLD AIR WL BE GUSTY NW
WNDS THU NGT INTO FRI.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
FOLLOWED CLOSE TO NAM WITH RESPECT TO FOG FORMATION IN THE TAFS AND
BROUGHT VISIBILITIES TO IFR IN TEMPO GROUPS BY 03Z AT SBY ECG AND
PHF DUE TO CURRENT TRENDS AND RUC BUFKIT. KEPT VISIBILITY NO LOWER THAN
3 MILES AT ORF. BUT EVENTUALLY DROPPED THEM BELOW ONE MILE
PREDOMINANTLY AT RIC SBY AND PHF. THERE ARE SOME INDICATIONS IN
THE NAM BUFKIT THAT IFR VISIBILITY AT ECG MAY BE INTERMITTENT.
CONDITIONS WILL BE SLOW TO IMPROVE DUE TO DEEP INVERSION AND VERY
LIGHT SURFACE WINDS. IN THE MORNING. IFR STRATUS EXPECTED UNTIL
14-16Z AT ALL BUT ORF.
OUTLOOK...THE NEXT CHANCE FOR RAIN COMES MID WEEK WITH THE
APPROACH OF A SLOW MOVING COLD FRONT.
&&
.MARINE...
SFC HI PRES OFFSHR RMNS IN CONTROL OVR THE WTRS THROUGH ERY PART OF
THE WK. SE TO S WNDS AOB 10 KT XPCTD THROUGH MON...W/ GRDL INCRS IN
SPDS MON NGT INTO TUE. SLO MVG CDFNT APPROACHES FM THE WNW TUE/TUE
NGT...THEN XPCTD TO SETTLE OVR THE WTRS WED. GOING CLSR TO
SREF/ECMWF SOLN W/ EVENTUALLY PUSH SWD OF FNTL BNDRY ON WED. WL HV
WNDS BCM MNLY N OVR THE FA ON WED AS FNTL SETTLES INTO FA.
TRACK/INSTENSITY OF SFC LO PRES ALG THE FNT LT WED INTO THU STILL
PROBLEMATIC ATTM. MOD/STRNG NW WNDS XPCTD BEHIND DEPARTING LO
PRES LT THU INTO FRI. NO HEADLINES NEEDED THROUGH MON NGT/TUE.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDM/MAS
NEAR TERM...MAM/LSA/MAS
SHORT TERM...JDM
LONG TERM...ALB
AVIATION...JEF/LSA
MARINE...ALB
AREA FORECAST DISCUSSION...UPDATED FOR 00Z TAFS
NWS MARQUETTE MI
615 PM EST TUE DEC 6 2011
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED A SHEARED MID/UPPER LEVEL
TROUGH FROM NRN ONTARIO THROUGH NW WI AND IA INTO THE CNTRL PLAINS.
AN UPSTREAM SHORTWAVE TROUGH WAS MOVING THROUGH CNTRL MANITOBA. AT
THE SFC...SW FLOW WAS INCREASING OVER WRN LAKE SUPERIOR AND W UPPER
MI BTWN A DEPARTING RIDGE FROM QUEBEC INTO EAST UPPER MI AND A
TROUGH OVER MANITOBA. ALTHOUGH THE BACKING WINDS HAVE PUSHED THE
LAKE CLOUDS OFFSHORE OVER THE CNTRL AND WEST CWA...LOWER LEVEL
MOISTURE OVER WRN WI WAS STREAMING BACK INTO THE WEST...PER VIS
LOOP. MID LEVEL CLOUDS WERE ADVANCING THROUGH NW ONTARIO AND NRN MN
ASSOCIATED WITH WAA/295K ISENTROPIC LIFT AHEAD OF THE TROUGH.
&&
.SHORT TERM...TONIGHT AND WEDNESDAY
MAIN FCST CONCERN IS LES POTENTIAL WITH THE FRONT/TROUGH MOVING
THROUGH THE AREA.
SATELLITE TRENDS AND NAM/RUC 925-900 MB RH FCST SUGGESTS THAT THE
LOWER CLOUDS WILL CONTINUE TO SPREAD TO THE EAST THIS EVENING AND
THEN MOVE OUT OVERNIGHT AS WINDS BEGIN TO VEER MORE TO THE WNW.
MODERATE MID LEVEL QVECTOR CONV ASSOCIATED WITH THE TROUGH MOVING
INTO THE AREA WED MORNING WILL BRING AN INCREASE IN 850-700 MB
MOISTURE. WITH WINDS VEERING WRLY AND 850 MB TEMPS TO AROUND
-11C...CONDITIONS WILL BECOME MORE FAVORABLE FOR LES INTO THE
KEWEENAW LATE TONIGHT INTO WED MORNING. CAA DROPS 850 MB TEMPS TO
AROUND -14C DURING THE AFTERNOON...BUT THE DEEPER MOISTURE IS
EXPECTED TO DEPART. SINCE THE PERIOD WITH THE COMBINATION OF LOW
LEVEL CONV AND 850-700 MB MOISTURE IS BRIEF...ANY LES
ACCUMULATIONS ARE EXPECTED TO BE LIGHT...GENERALLY AN INCH OR LESS.
SCT -SHSN WILL ALSO AFFECT LOCATIONS E OF MUNISING DURING THE
AFTERNOON BUT AGAIN ACCUMULATIONS SHOULD BE LIGHT.
.LONG TERM /WED NIGHT THROUGH NEXT TUESDAY/...
COLD FRONT THAT WILL START THE COOLING TREND WILL BE EAST OF THE
AREA AT THE START OF THE PERIOD...WHICH WILL PRODUCED A PROLONGED
LAKE EFFECT SNOW PERIOD FOR PORTIONS OF UPPER MICHIGAN.
EXPECT SFC LOW TO BE STATIONED OVER HUDSON BAY THROUGH SAT...WHILE A
SFC HIGH SHIFTS FROM THE NRN PLAINS ON THURS TO THE OHIO RIVER
VALLEY BY FRI NIGHT. THIS WILL LEAD TO WINDS OUT OF A WNW DIRECTION
ON WED NIGHT INTO THURS...THEN BACKING TO THE W FOR THURS NIGHT INTO
FRI NIGHT. THIS A LITTLE MORE WESTERLY THAN SHOWN YESTERDAY AND WILL
LIKELY FOCUS PCPN OVER THE ERN CWA TO BE FROM GRAND MARAIS
EASTWARD...RIGHT ALONG THE SHORELINE. THINK LAND BREEZES WILL HELP
FOCUS A DOMINATE BAND EITHER RIGHT ALONG THE SHORELINE OR JUST
OFFSHORE AT TIMES DURING THE PERIOD. OVER THE WEST...FAVORABLE
LOCATIONS WILL BE FROM ROCKLAND THROUGH COPPER HARBOR...ESPECIALLY
OVER THE HIGHER TERRAIN.
EXPECT LES TO BE ONGOING AT THE START OF THE PERIOD...BUT WILL
REALLY BEGIN TO RAMP UP OVERNIGHT WED INTO THURS MORNING...AS
SHORTWAVE AND SECONDARY SFC TROUGH SWEEP ACROSS THE AREA. THIS WILL
INCREASE MID LVL MOISTURE AND START A DOWNWARD TREND IN H850 TEMPS
FROM -14C /DELTA-T OF 19/ TO -20C OVER THE W AND -18C OVER THE E.
THESE VALUES DON/T LOOK AS COLD AS YESTERDAY FOR THE THURS/FRI TIME
FRAME...WHICH WILL BE MORE FAVORABLE FOR THE LES POTENTIAL...AS THE
DGZ WILL BE RIGHT IN THE BEST OMEGA. IN ADDITION...MODELS SHOWING A
MORE MOIST LLVL...WITH LESS SUB CLOUD LAYER DRY AIR. THIS ALLOWS THE
BEST LK INDUCED FORCING TO BE LOCATED DIRECTLY IN OR THE TOP HALF OF
THE DGZ AND AID FOR FASTER ACCUMULATION. THUS...HAVE BUMPED UP SLR
UP SLIGHTLY INTO THE LOW/MID 20S...ALTHOUGH NOT QUITE AS HIGH AS
SEEN ON SOME OF THE CARIBOU SLR VALUES.
MIGHT BE A LITTLE LULL IN LES OVER THE WEST ON THURS AFTN...AS DRIER
AIR ABOVE H800 MOVES THROUGH AND LOWERS THE INVERSION HEIGHTS. THIS
WILL BE SHORT LIVED AS NEXT WAVE OF DEEPER MOISTURE MOVES IN AND
INVERSION HEIGHTS RISE ON THURS NIGHT WITH THE UPPER TROUGH MOVING
OVERHEAD. EVEN WITH THIS LULL...THERE WILL STILL BE GUSTY WINDS THAT
WILL CREATE BLOWING/DRIFTING SNOW ALONG THE LK SUPERIOR SHORELINE
WITH THE FAIRLY FLUFFY SNOW THAT WILL HAVE FALLEN WED NIGHT INTO
THURS MORNING.
FRI DEEPER MOISTURE STARTS TO DEPART THE WEST DURING THE
DAY...STARTING TO DIMINISH LES INSTENSITY...BUT WILL STILL BE
ONGOING THROUGH FRI NIGHT. WITH WINDS SHIFTING MORE OUT OF THE
WSW...EXPECT BEST BANDS TO BE OVER THE KEWEENAW AND OFFSHORE OVER
THE E /ALTHOUGH A WEAK TROUGH COULD SLIDE THE BAND BACK ONSHORE FRI
NIGHT/.
AS FOR SNOWFALL AMOUNTS...LES PARAMETER EXCEEDS 2 FOR MUCH OF THE
PERIOD...WHICH ALONG WITH LK INDUCED CAPE VALUES EXCEEDING 700 J/KG
AND EQL/S IN THE 9-12KFT RANGE...THE POTENTIAL IS THERE FOR HEAVY
SNOWFALL ACCUMULATIONS. CURRENT FCST FROM 6Z THURS TO 6Z SAT HAS
12-20 INCHES OVER THE HIGHER TERRAIN FROM ROCKLAND TO CALUMET AND
SIMILAR TOTALS RIGHT ALONG THE LK SUPERIOR SHORELINE E OF GRAND
MARAIS. WILL LIKELY SEE A COUPLE PERIODS WHERE OUR 8IN/12HR WARN
CRITERIA WILL BE REACHED OVER THE WEST...SO HAVE PUT OUT A LES WATCH
FOR ONTONAGON THROUGH KEWEENAW COUNTIES. HAVE LIMITED CONFIDENCE IN
THE EAST WITH BAND LOCATION DUE TO THE LITTLE MORE WRLY WINDS AND
SOME LIKELY WANDERING OF THE BAND ON/OFF SHORE THROUGH THE
PERIOD...SO HELD OFF ON A WATCH FOR TIME BEING.
DAYS 4 THROUGH 7 /FRI NIGHT THROUGH NEXT TUESDAY/...
EXPECT LES TO COME TO AN END ON SAT...AS A CLIPPER SYSTEM DROPS
THROUGH SOUTHERN ONTARIO AND SHIFTS WINDS TO THE SW AND PRODUCES WAA
ALOFT. FINE DETAILS BECOME A LITTLE MORE MUDDLED FOR SUN THROUGH
TUES...AS NO MAJOR DISTURBANCES OR FEATURES AFFECT THE REGION. THIS
LEAVES THE AREA UNDER ZONAL FLOW ALOFT FOR SUN...AHEAD OF A
SHORTWAVE MOVING ACROSS THE AREA MON INTO MON NIGHT. WITH H850 TEMPS
AROUND -1C ON SUN...EXPECT TEMPS TO BE SLIGHTLY ABOVE NORMAL WITH
HIGHS IN THE LOWER 30S. SUN NIGHT INTO MON NIGHT SHOULD SEE A SFC
TROUGH NEAR THE UPPER GREAT LKS REGION...BUT WITH HOW WEAK IT
APPEARS TO BE WITH THE ZONAL FLOW...HAVE LIMITED CONFIDENCE ON PCPN.
THUS...WILL GO WITH A MOSTLY CLOUDY PERIOD...ALTHOUGH THE BEST
CHANCE FOR PCPN WILL BE MON INTO MON NIGHT. THESE CLOUDS WILL KEEP
OVERNIGHT LOWS FROM BEING TOO COLD AND KEEP TEMPS NEAR NORMAL FOR
MON INTO TUES.
&&
.AVIATION /FOR THE 00Z TAF ISSUANCE/
LOW LEVEL MOISTURE AND LOW CLOUDS ACROSS ERN IA AND CENTRAL WI WILL
CONTINUE TO ADVECT INTO THE AREA THIS EVENING CREATING SOME MVFR
CIGS THIS EVENING FOR A TIME. SW GRADIENT WINDS INCREASING THIS
EVENING AHEAD OF APPROACHING COLD FRONT WILL SUPPORT LLWS AT ALL TAF
SITES TONIGHT AND ALSO WILL ADEVECT IN SOME DRIER AIR TO GET RID OF
THE MVFR CIGS AND LOW CLOUDS. WINDS VEERING WRLY LATE TONIGHT BEHIND
THE FRONT SHOULD BRING MVFR CIGS BACK INTO KIWD AND KCMX LATE
TONIGHT. FAVORABLE WRLY FLOW AT KCMX MAY RESULT IN WIND GUSTS AOA 30
KTS AS WELL AS POSSIBLE LAKE EFFECT SNOW SHOWERS. DRIER AIR WILL
MOVE INTO KIWD WED MORNING AND KEEP LAKE EFFECT CLOUDS NORTH OF THE
SITE. KSAW WILL STAY VFR THROUGH THE PERIOD.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
SW WINDS ARE EXPECTED TO INCREASE TO GALE FORCE TONIGHT INTO EARLY
WED...MAINLY OVER WESTERN AND NCNTRL LAKE SUPERIOR AHEAD OF A TROUGH
MOVING TOWARD THE REGION. AS WINDS VEER NW BEHIND THE TROUGH...WINDS
ARE EXPECTED TO DIMINISH INTO THE 20-30 KT RANGE. A WINTRY PATTERN
OF W-NW WINDS WILL THEN PERSIST THRU LATE WEEK WITH LAKE EFFECT SNOW
SHOWERS. GIVEN ARCTIC AIR PASSING OVER THE LAKE AND EFFICIENT
MIXING...EXPECT WINDS CONSISTENTLY 20-30 KT WITH ANOTHER PERIOD OF
GALES POSSIBLE AGAIN LATE WED NIGHT AND THURSDAY. COMBINATION OF
ARCTIC AIR AND STRONG WIND SHOULD RESULT IN FREEZING SPRAY WED NIGHT
INTO FRIDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WATCH FROM LATE WEDNESDAY NIGHT THROUGH LATE
FRIDAY NIGHT FOR MIZ001>003.
LAKE SUPERIOR...
GALE WARNING UNTIL 10 AM EST WEDNESDAY FOR LSZ266.
GALE WARNING UNTIL 7 AM EST /6 AM CST/ WEDNESDAY FOR LSZ162.
GALE WARNING UNTIL 10 AM EST WEDNESDAY FOR LSZ263-264.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...JLB
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...07
MARINE...JLB
AREA FORECAST DISCUSSION...UPDATED FOR 00Z TAFS
NWS MARQUETTE MI
557 PM EST MON DEC 5 2011
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
HUDSON BAY AND NRN ONTARIO THROUGH THE NRN PLAINS TO THE SRN
ROCKIES. LITTLE LOW OR MID LEVEL FORCING WAS ASSOCIATED WITH
THE TROUGH IN THE VERY DRY AIRMASS UPSTREAM. AT THE SFC...A RIDGE
EXTENDED FROM NRN ONTARIO INTO THE NRN PLAINS RESULTING IN WEAK NRLY
LOW LEVEL FLOW ACROSS LAKE SUPERIOR INTO UPPER MI. RADAR INDICATED
LIGHT DISORGANIZED LES INTO UPPER MI. ACYC FLOW INTO THE REGION AND
SHEAR WITHIN THE SFC-850 MB LAYER HAS LIMITED INTENSITY WITH
GENERALLY LIGHT ACCUMULATIONS OF AN INCH OR LESS OBSERVED IN WEST
AND NORTH CENTRAL UPPER MI. SNOW RATIO HAS BEEN HIGH...TYPICAL OF
MOST LES...WITH THE CLOUD LAYER IN THE 2K-6K FT DGZ.
&&
.SHORT TERM...TONIGHT AND TUESDAY
SOME INCREASE IN LES INTENSITY MAY BE POSSIBLE THIS EVENING AS THE
MID LEVEL TROUGH MOVES INTO THE AREA AND 850 MB TEMPS DROP SLIGHTLY
TO NEAR -15C. HOWEVER...THE CBL FLOW WILL ALSO BECOME INCREASINGLY
ANTICYCLONIC AS THE SFC RIDGE AXIS SHIFTS OVER THE AREA. THIS WILL
ALLOW THE WINDS TO BACK OVERNIGHT WHICH WILL SHIFT THE BEST SNOWFALL
BY MORNING TO THE ONTONAGON TO THE KEWEENAW AS WELL AS ALGER COUNTY.
DESPITE THE FAVORABLE INSTABILITY AND MOISTURE...THE SHEAR COMBINED
WITH THE SHIFTING NATURE OF THE BANDS SHOULD LIMIT SNOWFALL TO 1-2
INCHES...MAINLY FROM IWD-CMX AND FROM MQT-P53. THE LIGHT WINDS MAY
ALLOW THE DEVELOPMENT OF A BAND ALONG THE SHORELINE INTO THE WEST
ANE NEAR MARQUETTE AS THE LAND BREEZE STRENGTHENS...PER
HIGH RES WRF/ARW BUT CONFIDENCE IN DETAILS FOR LES BAND EVOLUTION
IN THE LIGHT WIND REGIME IS LOW. A BRIEF PERIOD OF HEAVIER SNOW
WOULD BE POSSIBLE IF SUCH A BAND DEVELOPS.
ANY LES ACROSS THE KEWEENAW AND EAST OF MARQUETTE SHOULD RAPIDLY
SHIFT OFFSHORE ON TUESDAY AS THE RIDGE AXIS MOVES SOUTHEAST.
CONDITIONS SHOULD BE MORE PLEASANT BY AFTERNOON WITH SOME SUNSHINE
OVER THE AREA ALONG WITH RELATIVELY LIGHT SW WINDS.
.LONG TERM /TUES NIGHT THROUGH NEXT MONDAY/...
AT THE START OF THE PERIOD...AN ELONGATED UPPER TROUGH WILL BE
STRETCHING FROM JAMES BAY TO THE SRN PLAINS AND QUICKLY SHIFTING E
OF THE AREA. THIS WILL ALLOW A WEAK RIDGE...AHEAD OF THE MAIN UPPER
LOW TO AFFECT THE AREA DURING THE LONG TERM OVER THE NW TERRITORIES
OF CANADA. THIS WEAK UPPER RIDGE WILL CAUSE SFC RIDGE TO SLIDE E
ACROSS THE CWA TUES EVENING.
MIGHT SEE A QUICK COOL DOWN TUES EVENING WITH THE CLEAR SKIES AND
LIGHT WINDS...ESPECIALLY OVER THE CNTRL/ERN CWA...BUT INCREASING
SWRLY FLOW AND MID LEVEL CLOUDS AHEAD OF THE NEXT FRONT WILL LEVEL
TEMPS OFF AND MAY EVEN CAUSE THEM TO RISE SOME OVER THE WRN CWA.
WITH THE DEEPER MOISTURE AND H850-700 Q-VECTOR CONV ARRIVING LATE
TUES NIGHT...COULD SEE A FEW SNOW SHOWERS LATE TUES NIGHT OVER THE
KEWEENAW. BUT WITH THE BEST FORCING/MOISTURE OVER NRN LK
SUPERIOR...WILL KEEP THE CHANCES THERE. STRONGER PRESSURE GRADIENT
AHEAD OF THE FRONT WILL LIKELY LEAD TO SOME GALES OVER LK SUPERIOR
TUES NIGHT. EVEN WITH THE WAA ALOFT...LLVL WINDS BELOW THE INVERSION
LOOK TO BE IN THE 30-40KT RANGE AND WILL LIKELY ALSO LEAD TO A GUSTY
OVERNIGHT FOR THE HIGHER TERRAIN OF KEWEENAW PENINSULA. WILL
CONTINUE THE GALE WATCH OVER W/CNTRL LK SUPERIOR.
COLD FRONT MOVING THROUGH ON WED AND WILL USHER IN THE COLDEST AIR
OF THE SEASON. EXPECT THE MID LVL FORCING/MOISTURE TO BE THROUGH THE
AREA BY WED AFTN...AND WILL MOVE UP THE POP TIMING FROM THE PREVIOUS
SHIFT TO BE MORE IN THE MORNING FROM THE AFTN. MAY TAKE A LITTLE
WHILE FOR THE LES TO GET GOING BEHIND THE FRONT...AS INVERSION
HEIGHTS FALL TO 4.5-5.5KFT AND LLVL DRY AIR LIMITS ANY POTENTIAL
CLOUD DEPTH. THUS...WILL GO WITH SLIGHTS OVER THE WNW WIND FAVORED
LOCATIONS OVER THE WEST AND KEEP CHANCES OVER THE EAST WHERE THE
LOW-MID LVL MOISTURE WILL TRY TO LINGER LONGER. THINK THESE LIMITED
CONDITIONS WILL CONTINUE INTO THE EVENING HOURS BEFORE REALLY
INTENSIFYING THROUGH THE NIGHT.
THIS INTENSIFICATION WILL LARGELY BE DUE TO A SHORTWAVE MOVING
THROUGH ON WED NIGHT...WHICH WILL INCREASE THE LOW-MID LVL MOISTURE
AND PULL EVEN COLDER H850 TEMPS OVER THE AREA /STEADILY FALLING TO
NEAR -20C BY THURS EVENING/. THIS WILL INCREASE DELTA-T/S TO SOME
FAIRLY IMPRESSIVE VALUES /LOW-MID 20S BY THURS EVENING/. IN
ADDITION...WITH INVERSION HEIGHTS RISING TO 7-10KFT AND LK INDUCED
CAPES IN THE 500-700 J/KG RANGE...LOOKS TO BE A GOOD POTENTIAL FOR
AREAS TO RECEIVE MOD/HEAVY LES LATE WED NIGHT INTO THURS. LAKE
EFFECT SNOW PARAMATER SUPPORTS THIS POTENTIAL...RISING ABOVE
2...WHICH SUPPORTS A HIGH POTENTIAL FOR HEAVY SNOWFALL RATES...OVER
THE W WED NIGHT AND THE E ON THURS. WINDS LOOK TO BE OUT OF THE WNW
WED NIGHT INTO THURS...SO HAVE THE HIGHEST POPS IN THOSE FAVORED
LOCATIONS. ONE ITEM TO NOTE ON WIND DIRECTIONS IS THAT THE NAM/GEM
HINTING AT A MESO LOW FORMING OVER ERN LK SUPERIOR ON THURS...WHICH
COULD END UP FORCING WINDS MORE TO THE NW OVER THE WRN CWA. OVER THE
E...THIS COULD CAUSE A DOMINATE BAND TO SETUP SOMEWHERE OVER THE
SERN LAKE...POTENTIALLY RIGHT ALONG THE SHORELINE E OF GRAND MARAIS
DUE TO THE WSW WINDS AROUND THE MESO LOW. FINALLY...COULD BE A
SLIGHT LULL OVER THE W IN THE AFTN...AS SLIGHTLY DRIER AIR MOVES
THROUGH...AND HAVE SLIGHTLY LOWERED POPS FOR THAT TIMEFRAME.
DAYS 4 THROUGH 7 /THURS NIGHT THROUGH NEXT MONDAY/...
ARCTIC TROUGH DROPPING SE ACROSS THE AREA THURS NIGHT INTO SAT WILL
PROVIDE REINFORCING COLD AIR TO THE AREA AND CONTINUE THE LES.
EXPECT THE -16 TO -20C H850 TEMPS TO CONTINUE THURS NIGHT INTO FRI
NIGHT AS BL WINDS ARE FROM THE WNW THURS NIGHT INTO FRI AND THEN
START TO SHIFT TO THE WSW FRI NIGHT. WITH THE ABUNDANT LOW-MID LVL
MOISTURE UNDER THE UPPER TROUGH...THE INGREDIENTS ARE COMING
TOGETHER FOR A POTENTIALLY SIGNIFICANT LES PERIOD THURS NIGHT INTO
FRI FOR WNW WIND FAVORED LOCATIONS. AS MENTIONED PREVIOUSLY...LES
PARAMETER CONTINUES TO HIGHLIGHT THE HEAVY SNOW POTENTIAL...VALUES
ABOVE 2...THROUGH FRI FOR WNW WIND LOCATIONS. THIS IS ALSO SEEN IN
BUFKIT LK INDUCED CAPE VALUES EXCEEDING 700 J/KG AND EQL LVLS
BETWEEN 7-10KFT. IT IS A WAYS OUT...BUT BUFKIT SOUNDINGS ARE SHOWING
THE CLOUD BASES TO BE AT OR ABOVE THE DGZ AND LIMIT DENDRITES.
EITHER WAY...SHOULD SEE A HIGH SLR VALUE AND ALLOW FOR EASY
BLOWING/DRIFTING FOR AREAS NEAR LK SUPERIOR WHERE THE WINDS WILL BE
STRONGEST. IN ADDITION...THIS DRIER AIR IN THE LLVLS COULD ALSO LEAD
TO A COUPLE MAIN/DOMINATE BANDS. WILL STICK TO OUR LES CLIMO POP/SKY
GRIDS FOR THIS TIME FRAME AND WILL CONTINUE TO MENTION THE HEAVY
SNOW POTENTIAL IN THE HWO. WITH THE WINDS SHIFTING TO THE SW AND WAA
DEVELOPING ON SAT...EXPECT THE LES TO DIMINISH. THIS WAA IS DUE TO A
WEAK SHORTWAVE AND CLIPPER SYSTEM SLIDES THROUGH SOUTHERN
ONTARIO...WITH THE MAIN ENERGY/MOISTURE STAYING N OF THE CWA.
UPPER FLOW TRANSITIONS TO MORE ZONAL NRN STREAM ALONG THE
U.S./CANADA BORDER FOR SUN INTO MON. THIS ALLOWS WARMER H850
TEMPS...AROUND -1 TO 1C...TO MOVE OVER THE AREA AND LEAD TO A PERIOD
OF SLIGHTLY ABOVE NORMAL TEMPERATURES WITH HIGHS IN THE UPPER 20S
AND LOWER 30S. MODELS CONSISTENT ON SFC TROUGH SETTLING OVER THE
AREA SUN NIGHT INTO MON...AS SFC HIGHS ARE SETUP OVER THE NRN PLAINS
AND OHIO VALLEY. LIMITED UPPER LVL FORCING...SO HAVE KEPT THE FCST
DRY FOR NOW.
&&
.AVIATION /FOR THE 00Z TAF ISSUANCE/
FOR THIS FCST PERIOD...WEATHER AT TAF SITES WILL BE DOMINATED BY
LAKE EFFECT CLOUDS/SNOW SHOWERS WITH PREDOMINANT MVFR CIGS.
AS IS TYPICAL FOR LAKE EFFECT SNOW SHOWERS...VSBY WILL BE QUITE
VARIABLE...GENERALLY RANGING FROM MVFR TONIGHT. SOME IMPROVEMENT IN
VIS IS EXPECTED TUE MORNIN AS WINDS BACK MORE WNW AHEAD OF BUILDING
HIGH PRES RDG DIMINISHING SHSN. VFR CONDITIONS WILL OCCUR IN THE
LATE MORNING TO EARLY AFTERNOON AT ALL SITES.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
EXPECT WINDS MOSTLY IN THE 10-20 KT RANGE INTO TUE MORNING AS A HIGH
PRES RIDGE OVER NORTHERN ONTARIO AND THE NRN PLAINS SLOWLY BUILDS
ACROSS LAKE SUPERIOR. AS THE RIDGE SLIPS SE OF THE LAKE AND A COLD
FRONT APPROACHES...SW WINDS ARE EXPECTED TO INCREASE TO GALE FORCE
TUE NIGHT INTO EARLY WED...MAINLY OVER WESTERN AND NCNTRL LAKE
SUPERIOR. A WINTRY PATTERN OF W-NW WINDS WILL THEN PERSIST THRU LATE
WEEK WITH LAKE EFFECT SNOW SHOWERS. GIVEN ARCTIC AIR PASSING OVER
THE LAKE...EFFICIENT MIXING WITH 20-30 KT AND SOME GALE FORCE GUSTS
AT TIMES LATE IN THE WEEK. WITH ARCTIC AIRMASS INTO THE AREA SOME
FREEZING SPRAY MAY ALSO DEVELOP.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY MORNING FOR
LSZ266.
GALE WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING FOR
LSZ162.
GALE WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING FOR
LSZ263-264.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...JLB
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...07
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
401 PM EST MON DEC 5 2011
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
HUDSON BAY AND NRN ONTARIO THROUGH THE NRN PLAINS TO THE SRN
ROCKIES. LITTLE LOW OR MID LEVEL FORCING WAS ASSOCIATED WITH
THE TROUGH IN THE VERY DRY AIRMASS UPSTREAM. AT THE SFC...A RIDGE
EXTENDED FROM NRN ONTARIO INTO THE NRN PLAINS RESULTING IN WEAK NRLY
LOW LEVEL FLOW ACROSS LAKE SUPERIOR INTO UPPER MI. RADAR INDICATED
LIGHT DISORGANIZED LES INTO UPPER MI. ACYC FLOW INTO THE REGION AND
SHEAR WITHIN THE SFC-850 MB LAYER HAS LIMITED INTENSITY WITH
GENERALLY LIGHT ACCUMULATIONS OF AN INCH OR LESS OBSERVED IN WEST
AND NORTH CENTRAL UPPER MI. SNOW RATIO HAS BEEN HIGH...TYPICAL OF
MOST LES...WITH THE CLOUD LAYER IN THE 2K-6K FT DGZ.
&&
.SHORT TERM...TONIGHT AND TUESDAY
SOME INCREASE IN LES INTENSITY MAY BE POSSIBLE THIS EVENING AS THE
MID LEVEL TROUGH MOVES INTO THE AREA AND 850 MB TEMPS DROP SLIGHTLY
TO NEAR -15C. HOWEVER...THE CBL FLOW WILL ALSO BECOME INCREASINGLY
ANTICYCLONIC AS THE SFC RIDGE AXIS SHIFTS OVER THE AREA. THIS WILL
ALLOW THE WINDS TO BACK OVERNIGHT WHICH WILL SHIFT THE BEST SNOWFALL
BY MORNING TO THE ONTONAGON TO THE KEWEENAW AS WELL AS ALGER COUNTY.
DESPITE THE FAVORABLE INSTABILITY AND MOISTURE...THE SHEAR COMBINED
WITH THE SHIFTING NATURE OF THE BANDS SHOULD LIMIT SNOWFALL TO 1-2
INCHES...MAINLY FROM IWD-CMX AND FROM MQT-P53. THE LIGHT WINDS MAY
ALLOW THE DEVELOPMENT OF A BAND ALONG THE SHORELINE INTO THE WEST
ANE NEAR MARQUETTE AS THE LAND BREEZE STRENGTHENS...PER
HIGH RES WRF/ARW BUT CONFIDENCE IN DETAILS FOR LES BAND EVOLUTION
IN THE LIGHT WIND REGIME IS LOW. A BRIEF PERIOD OF HEAVIER SNOW
WOULD BE POSSIBLE IF SUCH A BAND DEVELOPS.
ANY LES ACROSS THE KEWEENAW AND EAST OF MARQUETTE SHOULD RAPIDLY
SHIFT OFFSHORE ON TUESDAY AS THE RIDGE AXIS MOVES SOUTHEAST.
CONDITIONS SHOULD BE MORE PLEASANT BY AFTERNOON WITH SOME SUNSHINE
OVER THE AREA ALONG WITH RELATIVELY LIGHT SW WINDS.
.LONG TERM /TUES NIGHT THROUGH NEXT MONDAY/...
AT THE START OF THE PERIOD...AN ELONGATED UPPER TROUGH WILL BE
STRETCHING FROM JAMES BAY TO THE SRN PLAINS AND QUICKLY SHIFTING E
OF THE AREA. THIS WILL ALLOW A WEAK RIDGE...AHEAD OF THE MAIN UPPER
LOW TO AFFECT THE AREA DURING THE LONG TERM OVER THE NW TERRITORIES
OF CANADA. THIS WEAK UPPER RIDGE WILL CAUSE SFC RIDGE TO SLIDE E
ACROSS THE CWA TUES EVENING.
MIGHT SEE A QUICK COOL DOWN TUES EVENING WITH THE CLEAR SKIES AND
LIGHT WINDS...ESPECIALLY OVER THE CNTRL/ERN CWA...BUT INCREASING
SWRLY FLOW AND MID LEVEL CLOUDS AHEAD OF THE NEXT FRONT WILL LEVEL
TEMPS OFF AND MAY EVEN CAUSE THEM TO RISE SOME OVER THE WRN CWA.
WITH THE DEEPER MOISTURE AND H850-700 Q-VECTOR CONV ARRIVING LATE
TUES NIGHT...COULD SEE A FEW SNOW SHOWERS LATE TUES NIGHT OVER THE
KEWEENAW. BUT WITH THE BEST FORCING/MOISTURE OVER NRN LK
SUPERIOR...WILL KEEP THE CHANCES THERE. STRONGER PRESSURE GRADIENT
AHEAD OF THE FRONT WILL LIKELY LEAD TO SOME GALES OVER LK SUPERIOR
TUES NIGHT. EVEN WITH THE WAA ALOFT...LLVL WINDS BELOW THE INVERSION
LOOK TO BE IN THE 30-40KT RANGE AND WILL LIKELY ALSO LEAD TO A GUSTY
OVERNIGHT FOR THE HIGHER TERRAIN OF KEWEENAW PENINSULA. WILL
CONTINUE THE GALE WATCH OVER W/CNTRL LK SUPERIOR.
COLD FRONT MOVING THROUGH ON WED AND WILL USHER IN THE COLDEST AIR
OF THE SEASON. EXPECT THE MID LVL FORCING/MOISTURE TO BE THROUGH THE
AREA BY WED AFTN...AND WILL MOVE UP THE POP TIMING FROM THE PREVIOUS
SHIFT TO BE MORE IN THE MORNING FROM THE AFTN. MAY TAKE A LITTLE
WHILE FOR THE LES TO GET GOING BEHIND THE FRONT...AS INVERSION
HEIGHTS FALL TO 4.5-5.5KFT AND LLVL DRY AIR LIMITS ANY POTENTIAL
CLOUD DEPTH. THUS...WILL GO WITH SLIGHTS OVER THE WNW WIND FAVORED
LOCATIONS OVER THE WEST AND KEEP CHANCES OVER THE EAST WHERE THE
LOW-MID LVL MOISTURE WILL TRY TO LINGER LONGER. THINK THESE LIMITED
CONDITIONS WILL CONTINUE INTO THE EVENING HOURS BEFORE REALLY
INTENSIFYING THROUGH THE NIGHT.
THIS INTENSIFICATION WILL LARGELY BE DUE TO A SHORTWAVE MOVING
THROUGH ON WED NIGHT...WHICH WILL INCREASE THE LOW-MID LVL MOISTURE
AND PULL EVEN COLDER H850 TEMPS OVER THE AREA /STEADILY FALLING TO
NEAR -20C BY THURS EVENING/. THIS WILL INCREASE DELTA-T/S TO SOME
FAIRLY IMPRESSIVE VALUES /LOW-MID 20S BY THURS EVENING/. IN
ADDITION...WITH INVERSION HEIGHTS RISING TO 7-10KFT AND LK INDUCED
CAPES IN THE 500-700 J/KG RANGE...LOOKS TO BE A GOOD POTENTIAL FOR
AREAS TO RECEIVE MOD/HEAVY LES LATE WED NIGHT INTO THURS. LAKE
EFFECT SNOW PARAMATER SUPPORTS THIS POTENTIAL...RISING ABOVE
2...WHICH SUPPORTS A HIGH POTENTIAL FOR HEAVY SNOWFALL RATES...OVER
THE W WED NIGHT AND THE E ON THURS. WINDS LOOK TO BE OUT OF THE WNW
WED NIGHT INTO THURS...SO HAVE THE HIGHEST POPS IN THOSE FAVORED
LOCATIONS. ONE ITEM TO NOTE ON WIND DIRECTIONS IS THAT THE NAM/GEM
HINTING AT A MESO LOW FORMING OVER ERN LK SUPERIOR ON THURS...WHICH
COULD END UP FORCING WINDS MORE TO THE NW OVER THE WRN CWA. OVER THE
E...THIS COULD CAUSE A DOMINATE BAND TO SETUP SOMEWHERE OVER THE
SERN LAKE...POTENTIALLY RIGHT ALONG THE SHORELINE E OF GRAND MARAIS
DUE TO THE WSW WINDS AROUND THE MESO LOW. FINALLY...COULD BE A
SLIGHT LULL OVER THE W IN THE AFTN...AS SLIGHTLY DRIER AIR MOVES
THROUGH...AND HAVE SLIGHTLY LOWERED POPS FOR THAT TIMEFRAME.
DAYS 4 THROUGH 7 /THURS NIGHT THROUGH NEXT MONDAY/...
ARCTIC TROUGH DROPPING SE ACROSS THE AREA THURS NIGHT INTO SAT WILL
PROVIDE REINFORCING COLD AIR TO THE AREA AND CONTINUE THE LES.
EXPECT THE -16 TO -20C H850 TEMPS TO CONTINUE THURS NIGHT INTO FRI
NIGHT AS BL WINDS ARE FROM THE WNW THURS NIGHT INTO FRI AND THEN
START TO SHIFT TO THE WSW FRI NIGHT. WITH THE ABUNDANT LOW-MID LVL
MOISTURE UNDER THE UPPER TROUGH...THE INGREDIENTS ARE COMING
TOGETHER FOR A POTENTIALLY SIGNIFICANT LES PERIOD THURS NIGHT INTO
FRI FOR WNW WIND FAVORED LOCATIONS. AS MENTIONED PREVIOUSLY...LES
PARAMETER CONTINUES TO HIGHLIGHT THE HEAVY SNOW POTENTIAL...VALUES
ABOVE 2...THROUGH FRI FOR WNW WIND LOCATIONS. THIS IS ALSO SEEN IN
BUFKIT LK INDUCED CAPE VALUES EXCEEDING 700 J/KG AND EQL LVLS
BETWEEN 7-10KFT. IT IS A WAYS OUT...BUT BUFKIT SOUNDINGS ARE SHOWING
THE CLOUD BASES TO BE AT OR ABOVE THE DGZ AND LIMIT DENDRITES.
EITHER WAY...SHOULD SEE A HIGH SLR VALUE AND ALLOW FOR EASY
BLOWING/DRIFTING FOR AREAS NEAR LK SUPERIOR WHERE THE WINDS WILL BE
STRONGEST. IN ADDITION...THIS DRIER AIR IN THE LLVLS COULD ALSO LEAD
TO A COUPLE MAIN/DOMINATE BANDS. WILL STICK TO OUR LES CLIMO POP/SKY
GRIDS FOR THIS TIME FRAME AND WILL CONTINUE TO MENTION THE HEAVY
SNOW POTENTIAL IN THE HWO. WITH THE WINDS SHIFTING TO THE SW AND WAA
DEVELOPING ON SAT...EXPECT THE LES TO DIMINISH. THIS WAA IS DUE TO A
WEAK SHORTWAVE AND CLIPPER SYSTEM SLIDES THROUGH SOUTHERN
ONTARIO...WITH THE MAIN ENERGY/MOISTURE STAYING N OF THE CWA.
UPPER FLOW TRANSITIONS TO MORE ZONAL NRN STREAM ALONG THE
U.S./CANADA BORDER FOR SUN INTO MON. THIS ALLOWS WARMER H850
TEMPS...AROUND -1 TO 1C...TO MOVE OVER THE AREA AND LEAD TO A PERIOD
OF SLIGHTLY ABOVE NORMAL TEMPERATURES WITH HIGHS IN THE UPPER 20S
AND LOWER 30S. MODELS CONSISTENT ON SFC TROUGH SETTLING OVER THE
AREA SUN NIGHT INTO MON...AS SFC HIGHS ARE SETUP OVER THE NRN PLAINS
AND OHIO VALLEY. LIMITED UPPER LVL FORCING...SO HAVE KEPT THE FCST
DRY FOR NOW.
&&
.AVIATION /FOR THE 18Z TAF ISSUANCE/
FOR THIS FCST PERIOD...WEATHER AT TAF SITES WILL BE DOMINATED BY
LAKE EFFECT CLOUDS/SNOW SHOWERS WITH PREDOMINANT MVFR CIGS.
AS IS TYPICAL FOR LAKE EFFECT SNOW SHOWERS...VSBY WILL BE QUITE
VARIABLE...GENERALLY RANGING FROM MVFR TO IFR TODAY. SOME
IMPROVEMENT IN VIS IS EXPECTED EARLY TUE AS WINDS BACK MORE
WNW AHEAD OF BUILDING HIGH PRES RDG DIMINISHING SHSN...ESPECIALLY AT
KIWD AND KSAW.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
EXPECT WINDS MOSTLY IN THE 10-20 KT RANGE INTO TUE MORNING AS A HIGH
PRES RIDGE OVER NORTHERN ONTARIO AND THE NRN PLAINS SLOWLY BUILDS
ACROSS LAKE SUPERIOR. AS THE RIDGE SLIPS SE OF THE LAKE AND A COLD
FRONT APPROACHES...SW WINDS ARE EXPECTED TO INCREASE TO GALE FORCE TUE
NIGHT INTO EARLY WED...MAINLY OVER WESTERN AND NCNTRL LAKE SUPERIOR.
A WINTRY PATTERN OF W-NW WINDS WILL THEN PERSIST THRU LATE WEEK WITH
LAKE EFFECT SNOW SHOWERS. GIVEN ARCTIC AIR PASSING OVER THE
LAKE...EFFICIENT MIXING WITH 20-30 KT AND SOME GALE FORCE GUSTS
AT TIMES LATE IN THE WEEK. WITH ARCTIC AIRMASS INTO THE AREA SOME
FREEZING SPRAY MAY ALSO DEVELOP.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY MORNING FOR
LSZ266.
GALE WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING FOR
LSZ162.
GALE WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING FOR
LSZ263-264.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...JLB
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
115 PM EST MON DEC 5 2011
UPDATED FOR 18Z AVIATION DISCUSSION
.DISCUSSION...
RECENT RADAR IMAGES ARE STARTING TO SHOW SOME ORGANIZATION TO THE
LES...ESPECIALLY JUST OFFSHORE OF MARQUETTE COUNTY AS WELL AS A
CONVERGENCE BAND JUST OFFSHORE NEAR SAXON HARBOR. WITH GENERAL LIGHT
WINDS ACROSS THE INLAND AREAS...STRONG LAND BREEZES HAVE DEVELOPED
THAT HAS HELPED THESE BANDS TO FORM. THE MAIN PROBLEM IS THAT LES
POTENTIAL IS STILL VERY UNCLEAR TODAY. IN A GENERAL SENSE...THE LES
IS HAVING A HARD TIME DEVELOPING THIS MORNING DESPITE 850MB TEMPS
AROUND -12C AND CONVERGENT NORTHERLY FLOW. 00Z SOUNDINGS FROM INL
AND YPL MAY SUGGEST WHY LES IS STRUGGLING WITH LOW INVERSION HEIGHTS
UNDER 4000 FT AND VERY DRY AIR ALOFT. MQT VWP SUGGESTS THAT THE
INVERSION IS HIGHER DOWNWIND OF LAKE SUPERIOR...BUT THE DRY AIR
ALOFT REMAINS A PROBLEM AS DOES THE SHEAR AT THE TOP OF THE
INVERSION. WITH THAT BEING SAID...THE RUC AND RAPID REFRESH SEEM TO
HAVE A GOOD HANDLE ON THE LES INITIATION ON THE LAND BREEZE
BOUNDARIES...AND EVEN THE 06Z NAM SUGGESTS SOME BETTER BANDS NEAR
IWD ASSOCIATED WITH THE LAND BREEZE. WILL REALLY NEED TO MONITOR THE
BAND JUST NORTH OF IWD THIS MORNING. AS THE LAND BREEZE BREAKS DOWN
THIS MORNING...THE BAND WILL LIKELY MOVE INLAND AS THE PRIMARY
SYNOPTIC FLOW REMAINS NORTHERLY THROUGH THE DAY. WITH THE COLDER
850MB TEMPS OVER THE WESTERN U.P. THIS MORNING...THE SNOW GROWTH
REGION WILL BE IN CONVECTIVE BOUNDARY LAYER WHICH SHOULD HELP SNOW
RATIOS RISE TO 20-25:1 TODAY. THIS WOULD SUGGEST THAT IT WOULD NOT
TAKE MUCH FOR ADVISORY LEVEL SNOW TO BE REACHED TODAY AROUND IWD
TODAY...ESPECIALLY SINCE DEEPER MOISTURE ARRIVES THIS AFTERNOON AS
THE WAVE CURRENTLY OVER MN MOVES ACROSS LAKE SUPERIOR. THIS SHOULD
HELP TO INCREASE LES COVERAGE AND INTENSITY ACROSS THE WEST LATER
THIS AFTERNOON AND ACROSS THE CENTRAL AND EASTERN FORECAST SNOWBELTS
TONIGHT. LAKE INDUCED INSTABILITY WILL ALSO BE HIGHER OVERNIGHT WITH
850MB TEMPS DROPPING TO -16C. HOWEVER...THE PBL FLOW WILL ALSO
BECOME INCREASINGLY ANTICYCLONIC AS THE NIGHT GOES ON AS THE SFC
RIDGE AXIS SHIFTS OVER THE AREA. THIS WILL ALLOW THE WINDS TO BACK
OVERNIGHT WHICH WILL SHIFT THE BEST SNOWFALL BY MORNING TO THE
ONTONAGON TO THE KEWEENAW AS WELL AS ALGER COUNTY. DESPITE THE
FAVORABLE INSTABILITY AND MOISTURE...THE SHEAR IN PBL COMBINED WITH
THE SHIFTING NATURE OF THE BANDS SHOULD LIMIT SNOWFALL TO 1-3
INCHES...MAINLY FROM IWD-CMX AND FROM MQT-P53.
ANY LES ACROSS THE KEWEENAW AND EAST OF MARQUETTE SHOULD RAPIDLY
SHIFT OFFSHORE ON TUESDAY AS THE RIDGE AXIS MOVES SOUTHEAST. WILL
END UP BEING A DECENT AFTERNOON ON TUESDAY WITH SOME SUNSHINE NOT
OUT OF THE QUESTION. CLEAR SKIES SHOULD ALLOW TEMPS TO DROP INTO THE
SINGLE DIGITS BY WED MORNING ACROSS MANY INTERIOR LOCATIONS. THE
NEXT FRONT WILL PASS THROUGH THE AREA WEDNESDAY. THIS FRONT WILL
USHER IN THE COLDEST AIR OF THE SEASON SO FAR. IT STILL LOOKS LIKE A
RATHER SNOWY PERIOD FOR AREAS FAVORED IN W-NW FLOW SUCH AS THE
KEWEENAW PENINUSLA AND AREAS EAST OF MUNISING. IN ADDITION TO THE
PURE LAKE EFFECT...THERE WILL BE SEVERAL OPPORTUNITIES FOR LAKE
ENHANCEMENT AS UPPER DISTURBANCES ROTATE AROUND THE HUDSON BAY LOW.
ALTHOUGH IT IS TOO EARLY FOR ANY WATCHES...PEOPLE IN THE KEWEENAW
AND AREAS EAST OF MUNISING SHOULD SEE SIGNIFICANT SNOW ACCUMULATIONS
FROM WED NIGHT THROUGH FRIDAY (AND PERHAPS EVEN INTO SATURDAY). THE
GFS SOUNDINGS SHOW INVERSION HEIGHTS AROUND 8000 FT WITH LAKE
INDUCED CAPE VALUES AT LEAST 800 J/KG BY THU. ONLY CONCERN FOR A
MAJOR LAKE EFFECT SNOW EVENT IS THE DRY BOUNDARY LAYER WHICH WILL
UNDOUBTEDLY ACCOMPANY THE ARCTIC AIRMASS. FOR NOW...WILL CONTINUE TO
MENTION THE POSSIBILITY FOR HEAVY LES IN THE HAZARDOUS WEATHER
OUTLOOK.
OTHERWISE...THE WEATHER FOR AREAS AWAY FROM LES SHOULD BE FAIRLY
QUIET THROUGH MUCH OF THE WEEK. IT WILL BE MUCH COLDER THAN NORMAL
FOR THU-SAT WITH TEMPS STRUGGLING TO RISE INTO THE 20S. BY
SUNDAY...HEIGHT RISES WILL ALLOW FOR THE LES TO END AND TEMPS TO
RISE BACK TO NEAR NORMAL AS THE FLOW TURNS SWLY.
&&
.AVIATION /FOR THE 18Z TAF ISSUANCE/
FOR THIS FCST PERIOD...WEATHER AT TAF SITES WILL BE DOMINATED BY
LAKE EFFECT CLOUDS/SNOW SHOWERS WITH PREDOMINANT MVFR CIGS.
AS IS TYPICAL FOR LAKE EFFECT SNOW SHOWERS...VSBY WILL BE QUITE
VARIABLE...GENERALLY RANGING FROM MVFR TO IFR TODAY. SOME
IMPROVEMENT IN VIS IS EXPECTED EARLY TUE AS WINDS BACK MORE
WNW AHEAD OF BUILDING HIGH PRES RDG DIMINISHING SHSN...ESPECIALLY AT
KIWD AND KSAW.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
EXPECT WINDS MOSTLY IN THE 10-20 KT RANGE THROUGH TUE AS A HIGH PRES
RIDGE OVER NORTHERN ONTARIO AND THE NRN PLAINS SLOWLY BUILDS ACROSS
LAKE SUPERIOR. AS THE RIDGE SLIPS SE OF THE LAKE AND A COLD
FRONT APPROACHES...SW WINDS WILL LIKELY INCREASE TO GALE FORCE TUE
NIGHT INTO EARLY WED...MAINLY OVER WESTERN AND NCNTRL LAKE SUPERIOR.
A WINTRY PATTERN OF W-NW WINDS WILL THEN PERSIST THRU LATE WEEK WITH
LAKE EFFECT SNOW SHOWERS. GIVEN ARCTIC AIR PASSING OVER THE
LAKE...EFFICIENT MIXING MAY RESULT IN BRIEF GALES AT TIMES LATE IN
THE WEEK. MAY NEED TO CONSIDER THE POTENTIAL OF FREEZING SPRAY AS
WELL.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY MORNING FOR
LSZ266.
GALE WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING FOR
LSZ162.
GALE WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING FOR
LSZ263-264.
LAKE MICHIGAN...
NONE.
&&
$$
DISCUSSION...MRD
AVIATION...JLB
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
733 AM EST MON DEC 5 2011
.DISCUSSION...
RECENT RADAR IMAGES ARE STARTING TO SHOW SOME ORGANIZATION TO THE
LES...ESPECIALLY JUST OFFSHORE OF MARQUETTE COUNTY AS WELL AS A
CONVERGENCE BAND JUST OFFSHORE NEAR SAXON HARBOR. WITH GENERAL LIGHT
WINDS ACROSS THE INLAND AREAS...STRONG LAND BREEZES HAVE DEVELOPED
THAT HAS HELPED THESE BANDS TO FORM. THE MAIN PROBLEM IS THAT LES
POTENTIAL IS STILL VERY UNCLEAR TODAY. IN A GENERAL SENSE...THE LES
IS HAVING A HARD TIME DEVELOPING THIS MORNING DESPITE 850MB TEMPS
AROUND -12C AND CONVERGENT NORTHERLY FLOW. 00Z SOUNDINGS FROM INL
AND YPL MAY SUGGEST WHY LES IS STRUGGLING WITH LOW INVERSION HEIGHTS
UNDER 4000 FT AND VERY DRY AIR ALOFT. MQT VWP SUGGESTS THAT THE
INVERSION IS HIGHER DOWNWIND OF LAKE SUPERIOR...BUT THE DRY AIR
ALOFT REMAINS A PROBLEM AS DOES THE SHEAR AT THE TOP OF THE
INVERSION. WITH THAT BEING SAID...THE RUC AND RAPID REFRESH SEEM TO
HAVE A GOOD HANDLE ON THE LES INITIATION ON THE LAND BREEZE
BOUNDARIES...AND EVEN THE 06Z NAM SUGGESTS SOME BETTER BANDS NEAR
IWD ASSOCIATED WITH THE LAND BREEZE. WILL REALLY NEED TO MONITOR THE
BAND JUST NORTH OF IWD THIS MORNING. AS THE LAND BREEZE BREAKS DOWN
THIS MORNING...THE BAND WILL LIKELY MOVE INLAND AS THE PRIMARY
SYNOPTIC FLOW REMAINS NORTHERLY THROUGH THE DAY. WITH THE COLDER
850MB TEMPS OVER THE WESTERN U.P. THIS MORNING...THE SNOW GROWTH
REGION WILL BE IN CONVECTIVE BOUNDARY LAYER WHICH SHOULD HELP SNOW
RATIOS RISE TO 20-25:1 TODAY. THIS WOULD SUGGEST THAT IT WOULD NOT
TAKE MUCH FOR ADVISORY LEVEL SNOW TO BE REACHED TODAY AROUND IWD
TODAY...ESPECIALLY SINCE DEEPER MOISTURE ARRIVES THIS AFTERNOON AS
THE WAVE CURRENTLY OVER MN MOVES ACROSS LAKE SUPERIOR. THIS SHOULD
HELP TO INCREASE LES COVERAGE AND INTENSITY ACROSS THE WEST LATER
THIS AFTERNOON AND ACROSS THE CENTRAL AND EASTERN FORECAST SNOWBELTS
TONIGHT. LAKE INDUCED INSTABILITY WILL ALSO BE HIGHER OVERNIGHT WITH
850MB TEMPS DROPPING TO -16C. HOWEVER...THE PBL FLOW WILL ALSO
BECOME INCREASINGLY ANTICYCLONIC AS THE NIGHT GOES ON AS THE SFC
RIDGE AXIS SHIFTS OVER THE AREA. THIS WILL ALLOW THE WINDS TO BACK
OVERNIGHT WHICH WILL SHIFT THE BEST SNOWFALL BY MORNING TO THE
ONTONAGON TO THE KEWEENAW AS WELL AS ALGER COUNTY. DESPITE THE
FAVORABLE INSTABILITY AND MOISTURE...THE SHEAR IN PBL COMBINED WITH
THE SHIFTING NATURE OF THE BANDS SHOULD LIMIT SNOWFALL TO 1-3
INCHES...MAINLY FROM IWD-CMX AND FROM MQT-P53.
ANY LES ACROSS THE KEWEENAW AND EAST OF MARQUETTE SHOULD RAPIDLY
SHIFT OFFSHORE ON TUESDAY AS THE RIDGE AXIS MOVES SOUTHEAST. WILL
END UP BEING A DECENT AFTERNOON ON TUESDAY WITH SOME SUNSHINE NOT
OUT OF THE QUESTION. CLEAR SKIES SHOULD ALLOW TEMPS TO DROP INTO THE
SINGLE DIGITS BY WED MORNING ACROSS MANY INTERIOR LOCATIONS. THE
NEXT FRONT WILL PASS THROUGH THE AREA WEDNESDAY. THIS FRONT WILL
USHER IN THE COLDEST AIR OF THE SEASON SO FAR. IT STILL LOOKS LIKE A
RATHER SNOWY PERIOD FOR AREAS FAVORED IN W-NW FLOW SUCH AS THE
KEWEENAW PENINUSLA AND AREAS EAST OF MUNISING. IN ADDITION TO THE
PURE LAKE EFFECT...THERE WILL BE SEVERAL OPPORTUNITIES FOR LAKE
ENHANCEMENT AS UPPER DISTURBANCES ROTATE AROUND THE HUDSON BAY LOW.
ALTHOUGH IT IS TOO EARLY FOR ANY WATCHES...PEOPLE IN THE KEWEENAW
AND AREAS EAST OF MUNISING SHOULD SEE SIGNIFICANT SNOW ACCUMULATIONS
FROM WED NIGHT THROUGH FRIDAY (AND PERHAPS EVEN INTO SATURDAY). THE
GFS SOUNDINGS SHOW INVERSION HEIGHTS AROUND 8000 FT WITH LAKE
INDUCED CAPE VALUES AT LEAST 800 J/KG BY THU. ONLY CONCERN FOR A
MAJOR LAKE EFFECT SNOW EVENT IS THE DRY BOUNDARY LAYER WHICH WILL
UNDOUBTEDLY ACCOMPANY THE ARCTIC AIRMASS. FOR NOW...WILL CONTINUE TO
MENTION THE POSSIBILITY FOR HEAVY LES IN THE HAZARDOUS WEATHER
OUTLOOK.
OTHERWISE...THE WEATHER FOR AREAS AWAY FROM LES SHOULD BE FAIRLY
QUIET THROUGH MUCH OF THE WEEK. IT WILL BE MUCH COLDER THAN NORMAL
FOR THU-SAT WITH TEMPS STRUGGLING TO RISE INTO THE 20S. BY
SUNDAY...HEIGHT RISES WILL ALLOW FOR THE LES TO END AND TEMPS TO
RISE BACK TO NEAR NORMAL AS THE FLOW TURNS SWLY.
&&
.AVIATION /FOR THE 12Z TAF ISSUANCE/
FOR THIS FCST PERIOD...WEATHER AT KIWD/KCMX/KSAW WILL BE DOMINATED
BY LAKE EFFECT CLOUDS/SNOW SHOWERS. MVFR CIGS WILL DOMINATE. AS IS
TYPICAL FOR LAKE EFFECT SNOW SHOWERS...VIS WILL BE QUITE
VARIABLE...GENERALLY RANGING FROM MVFR TO IFR TODAY. LOWER VIS
SHOULD BE MORE COMMON TODAY INTO THIS EVENING AS OVERWATER
INSTABILITY INCREASES...RESULTING IN THE POTENTIAL OF INCREASED
-SHSN INTENSITY. SOME IMPROVEMENT IN VIS IS EXPECTED LATE TONIGHT AS
WINDS BACK MORE WNW AHEAD OF BUILDING HIGH PRES RDG DIMINISHING
SHSN...ESPECIALLY AT KIWD AND KSAW.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
EXPECT WINDS MOSTLY IN THE 10-20 KT RANGE THROUGH TUE AS A HIGH PRES
RIDGE OVER NORTHERN ONTARIO AND THE NRN PLAINS SLOWLY BUILDS ACROSS
LAKE SUPERIOR. AS THE RIDGE SLIPS SE OF THE LAKE AND A COLD
FRONT APPROACHES...SW WINDS WILL LIKELY INCREASE TO GALE FORCE TUE
NIGHT INTO EARLY WED...MAINLY OVER WESTERN AND NCNTRL LAKE SUPERIOR.
A WINTRY PATTERN OF W-NW WINDS WILL THEN PERSIST THRU LATE WEEK WITH
LAKE EFFECT SNOW SHOWERS. GIVEN ARCTIC AIR PASSING OVER THE
LAKE...EFFICIENT MIXING MAY RESULT IN BRIEF GALES AT TIMES LATE IN
THE WEEK. MAY NEED TO CONSIDER THE POTENTIAL OF FREEZING SPRAY AS
WELL.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY MORNING FOR
LSZ266.
GALE WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING FOR
LSZ162.
GALE WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING FOR
LSZ263-264.
LAKE MICHIGAN...
NONE.
&&
$$
DISCUSSION...MRD
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
502 AM EST MON DEC 5 2011
.DISCUSSION...
RECENT RADAR IMAGES ARE STARTING TO SHOW SOME ORGANIZATION TO THE
LES...ESPECIALLY JUST OFFSHORE OF MARQUETTE COUNTY AS WELL AS A
CONVERGENCE BAND JUST OFFSHORE NEAR SAXON HARBOR. WITH GENERAL LIGHT
WINDS ACROSS THE INLAND AREAS...STRONG LAND BREEZES HAVE DEVELOPED
THAT HAS HELPED THESE BANDS TO FORM. THE MAIN PROBLEM IS THAT LES
POTENTIAL IS STILL VERY UNCLEAR TODAY. IN A GENERAL SENSE...THE LES
IS HAVING A HARD TIME DEVELOPING THIS MORNING DESPITE 850MB TEMPS
AROUND -12C AND CONVERGENT NORTHERLY FLOW. 00Z SOUNDINGS FROM INL
AND YPL MAY SUGGEST WHY LES IS STRUGGLING WITH LOW INVERSION HEIGHTS
UNDER 4000 FT AND VERY DRY AIR ALOFT. MQT VWP SUGGESTS THAT THE
INVERSION IS HIGHER DOWNWIND OF LAKE SUPERIOR...BUT THE DRY AIR
ALOFT REMAINS A PROBLEM AS DOES THE SHEAR AT THE TOP OF THE
INVERSION. WITH THAT BEING SAID...THE RUC AND RAPID REFRESH SEEM TO
HAVE A GOOD HANDLE ON THE LES INITIATION ON THE LAND BREEZE
BOUNDARIES...AND EVEN THE 06Z NAM SUGGESTS SOME BETTER BANDS NEAR
IWD ASSOCIATED WITH THE LAND BREEZE. WILL REALLY NEED TO MONITOR THE
BAND JUST NORTH OF IWD THIS MORNING. AS THE LAND BREEZE BREAKS DOWN
THIS MORNING...THE BAND WILL LIKELY MOVE INLAND AS THE PRIMARY
SYNOPTIC FLOW REMAINS NORTHERLY THROUGH THE DAY. WITH THE COLDER
850MB TEMPS OVER THE WESTERN U.P. THIS MORNING...THE SNOW GROWTH
REGION WILL BE IN CONVECTIVE BOUNDARY LAYER WHICH SHOULD HELP SNOW
RATIOS RISE TO 20-25:1 TODAY. THIS WOULD SUGGEST THAT IT WOULD NOT
TAKE MUCH FOR ADVISORY LEVEL SNOW TO BE REACHED TODAY AROUND IWD
TODAY...ESPECIALLY SINCE DEEPER MOISTURE ARRIVES THIS AFTERNOON AS
THE WAVE CURRENTLY OVER MN MOVES ACROSS LAKE SUPERIOR. THIS SHOULD
HELP TO INCREASE LES COVERAGE AND INTENSITY ACROSS THE WEST LATER
THIS AFTERNOON AND ACROSS THE CENTRAL AND EASTERN FORECAST SNOWBELTS
TONIGHT. LAKE INDUCED INSTABILITY WILL ALSO BE HIGHER OVERNIGHT WITH
850MB TEMPS DROPPING TO -16C. HOWEVER...THE PBL FLOW WILL ALSO
BECOME INCREASINGLY ANTICYCLONIC AS THE NIGHT GOES ON AS THE SFC
RIDGE AXIS SHIFTS OVER THE AREA. THIS WILL ALLOW THE WINDS TO BACK
OVERNIGHT WHICH WILL SHIFT THE BEST SNOWFALL BY MORNING TO THE
ONTONAGON TO THE KEWEENAW AS WELL AS ALGER COUNTY. DESPITE THE
FAVORABLE INSTABILITY AND MOISTURE...THE SHEAR IN PBL COMBINED WITH
THE SHIFTING NATURE OF THE BANDS SHOULD LIMIT SNOWFALL TO 1-3
INCHES...MAINLY FROM IWD-CMX AND FROM MQT-P53.
ANY LES ACROSS THE KEWEENAW AND EAST OF MARQUETTE SHOULD RAPIDLY
SHIFT OFFSHORE ON TUESDAY AS THE RIDGE AXIS MOVES SOUTHEAST. WILL
END UP BEING A DECENT AFTERNOON ON TUESDAY WITH SOME SUNSHINE NOT
OUT OF THE QUESTION. CLEAR SKIES SHOULD ALLOW TEMPS TO DROP INTO THE
SINGLE DIGITS BY WED MORNING ACROSS MANY INTERIOR LOCATIONS. THE
NEXT FRONT WILL PASS THROUGH THE AREA WEDNESDAY. THIS FRONT WILL
USHER IN THE COLDEST AIR OF THE SEASON SO FAR. IT STILL LOOKS LIKE A
RATHER SNOWY PERIOD FOR AREAS FAVORED IN W-NW FLOW SUCH AS THE
KEWEENAW PENINUSLA AND AREAS EAST OF MUNISING. IN ADDITION TO THE
PURE LAKE EFFECT...THERE WILL BE SEVERAL OPPORTUNITIES FOR LAKE
ENHANCEMENT AS UPPER DISTURBANCES ROTATE AROUND THE HUDSON BAY LOW.
ALTHOUGH IT IS TOO EARLY FOR ANY WATCHES...PEOPLE IN THE KEWEENAW
AND AREAS EAST OF MUNISING SHOULD SEE SIGNIFICANT SNOW ACCUMULATIONS
FROM WED NIGHT THROUGH FRIDAY (AND PERHAPS EVEN INTO SATURDAY). THE
GFS SOUNDINGS SHOW INVERSION HEIGHTS AROUND 8000 FT WITH LAKE
INDUCED CAPE VALUES AT LEAST 800 J/KG BY THU. ONLY CONCERN FOR A
MAJOR LAKE EFFECT SNOW EVENT IS THE DRY BOUNDARY LAYER WHICH WILL
UNDOUBTEDLY ACCOMPANY THE ARCTIC AIRMASS. FOR NOW...WILL CONTINUE TO
MENTION THE POSSIBILITY FOR HEAVY LES IN THE HAZARDOUS WEATHER
OUTLOOK.
OTHERWISE...THE WEATHER FOR AREAS AWAY FROM LES SHOULD BE FAIRLY
QUIET THROUGH MUCH OF THE WEEK. IT WILL BE MUCH COLDER THAN NORMAL
FOR THU-SAT WITH TEMPS STRUGGLING TO RISE INTO THE 20S. BY
SUNDAY...HEIGHT RISES WILL ALLOW FOR THE LES TO END AND TEMPS TO
RISE BACK TO NEAR NORMAL AS THE FLOW TURNS SWLY.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/
FOR THIS FCST PERIOD...WEATHER AT KIWD/KCMX/KSAW WILL BE DOMINATED
BY LAKE EFFECT CLOUDS/SNOW SHOWERS. MVFR CIGS WILL DOMINATE. AS IS
TYPICAL FOR LAKE EFFECT SNOW SHOWERS...VIS WILL BE QUITE
VARIABLE...RANGING FROM VFR VIS WITH NO PCPN TO MVFR. LOWER VIS
SHOULD BE MORE COMMON LATER TONIGHT INTO MON MORNING AS OVERWATER
INSTABILITY INCREASES...RESULTING IN POTENTIAL OF INCREASED -SHSN
INTENSITY AND THIS STAYS THAT WAY THROUGH THE PERIOD.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
EXPECT WINDS MOSTLY IN THE 10-20 KT RANGE THROUGH TUE AS A HIGH PRES
RIDGE OVER NORTHERN ONTARIO AND THE NRN PLAINS SLOWLY BUILDS ACROSS
LAKE SUPERIOR. AS THE RIDGE SLIPS SE OF THE LAKE AND A COLD
FRONT APPROACHES...SW WINDS WILL LIKELY INCREASE TO GALE FORCE TUE
NIGHT INTO EARLY WED...MAINLY OVER WESTERN AND NCNTRL LAKE SUPERIOR.
A WINTRY PATTERN OF W-NW WINDS WILL THEN PERSIST THRU LATE WEEK WITH
LAKE EFFECT SNOW SHOWERS. GIVEN ARCTIC AIR PASSING OVER THE
LAKE...EFFICIENT MIXING MAY RESULT IN BRIEF GALES AT TIMES LATE IN
THE WEEK. MAY NEED TO CONSIDER THE POTENTIAL OF FREEZING SPRAY AS
WELL.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY MORNING FOR
LSZ266.
GALE WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING FOR
LSZ162.
GALE WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING FOR
LSZ263-264.
LAKE MICHIGAN...
NONE.
&&
$$
DISCUSSION...MRD
AVIATION...07
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS GLASGOW MT
905 PM MST SUN DEC 4 2011
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH TUESDAY...
EVENING UPDATE...
NO CHANGES ARE PLANNED FOR THE FORECAST. CURRENTLY LOW LEVEL CLOUD
COVER IS THE DOMINATE FEATURE IN DETERMINING OVERNIGHT LOWS.
WHETHER AND AREA CLEARS OUT OR NOT WILL HAVE A 5 TO 10 DEGREE
DIFFERENCE IN OVERNIGHT LOWS. HAVE PLANNED ON MOST OF THE AREA
CLEARING SLOWLY AS LOW LEVEL CLOUD COVER DISSIPATES BEFORE SUNRISE
LIKE THE HRRR MODEL INDICATES. GAH
LATE AFTERNOON UPDATE...
WINDS HAVE DIMINISHED AND VISIBILITIES HAVE IMPROVED IN OUR SE
COUNTIES. THEREFORE ALLOWED THE WSW TO EXPIRE ON TIME AT 00Z.
OCCASIONAL LIGHT SNOW IS STILL POSSIBLE BUT NO ADDITIONAL
ACCUMULATION IS EXPECTED. SCT
AFTERNOON DISCUSSION...
BASED ON WEATHER CAMS...AIRPORT OBSERVATIONS AND LOW VISIBILITIES
FROM SNOW AND BLOWING SNOW...KEPT THE WSW GOING FOR THE SOUTHEAST
ZONES. THE WSW WILL BE REVISITED NEAR 00Z WHEN IT IS SCHEDULED TO
END.
THE SHORT TERM PERIOD WILL INTRODUCE A QUIET PERIOD THROUGH
TUESDAY. TONIGHT A SURFACE HIGH SLIDES SOUTH OVER NORTHEAST
MONTANA AS THE UPPER LEVEL TROUGH MOVES TO OUR EAST. THE SURFACE
HIGH WILL DIMINISH WINDS THIS EVENING TO LIGHT AND VARIABLE AFTER
MIDNIGHT. GOES VISUAL IMAGERY REVEALS CLEARING UPSTREAM IN
SASKATCHEWAN. THEREFORE...SUPPORTED BY MODEL DATA...EXPECT
CLEARING FROM THE NORTH. WITH 1000MB-500MB THICKNESS HEIGHTS
BOTTOMING OUT AT AROUND 505DM AND CLEARING SKIES...THE LOWS
TONIGHT WILL DROP TO BELOW ZERO IN MOST AREAS. COLD AIR DRAINAGE
IS EXPECTED TO ENHANCE TERRAIN DIFFERENCES DUE TO LIGHT SYNOPTIC
WINDS. WITH LIGHT WINDS THE WIND CHILLS SHOULD NOT BE AN ISSUE.
MONDAY/TUESDAY...AN EAST LEANING UPPER LEVEL CHINOOK RIDGE PUSHES
INTO THE PACNW SENDING A WARM FRONT EAST ACROSS MONTANA. PLUS THE
SURFACE HIGH MOVES SOUTH OF NEMONT...SHIFTING SURFACE WINDS TO THE
SOUTHWEST. THIS WILL START A WARMING TREND WITH TEMPERATURES
APPROACHING NORMAL BY TUESDAY. HOWEVER...NEW SNOW COVER MAY
DAMPER A RAPID RETURN AND SLOW SNOW MELT ON MONDAY. YET...BY
TUESDAY A PRE-FRONTAL WARMING SPIKE IN ADDITION TO CONSTANT EROSION
OF THE SNOW COVER BY THE CHINOOK FROM THE NIGHT BEFORE MAY BE
ABLE TO EXPOSE SOME BARE GROUND BEFORE THE NEXT FRONTS ARRIVAL
LATER IN THE WEEK. SCT
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
THE ONLY CHANGES MADE FOR THE AFTERNOON FORECAST ISSUANCE WAS TO
EXPAND PRECIPITATION COVERAGE FOR WEDNESDAY AS THE FORECAST MODELS
NOW SUPPORT PRECIPITATION FURTHER TO THE NORTH AND EAST THEN
PREVIOUSLY FORECAST. ALSO PUT IN SOME SLIGHT CHANCE POPS ACROSS
THE NORTH FOR SUNDAY AS THE MODELS ARE HINTING AT ANOTHER WAVE
DROPPING SOUTHWARD OUT OF CANADA. OTHERWISE THE REMAINDER OF THE
FORECAST AS DISCUSSED BELOW IS ON TRACK. GILCHRIST
PREVIOUS LONG TERM DISCUSSION...ANOTHER PUSH OF COLD AIR EXPECTED
MIDWEEK AS UPPER LOW SLIDES FROM NORTHERN ALASKA TOWARD HUDSON
BAY...WITH THE POLAR JET DIVING INTO CENTRAL CANADA. COLD FRONT
DROPS INTO MONTANA TUESDAY NIGHT WITH STRONG THERMAL DYNAMICS BUT
MOISTURE LIMITED MINIMIZING CHANCES OF SNOW. AS COLD AIR CONTINUES
TO SLIDE INTO MONTANA THE AVAILABLE MOISTURE IMPROVES AS IT POOLS
AGAINST THE MOUNTAINS OF WESTERN AND SOUTHERN MONTANA. UPSLOPE
WILL ADD LIFT FOR SNOW DEVELOPING ACROSS CENTRAL MONTANA WEDNESDAY
NIGHT INTO THURSDAY. TEMPERATURES BECOME QUITE FRIGID BY THURSDAY
AS THE ARCTIC BUILDS SOUTHWARD.
TEMPERATURES BEGIN TO MODERATE INTO THE END OF THE WEEK AS RIDGE
PUSHES ACROSS THE NORTHERN ROCKIES. MODELS DIFFERING ON THE EXTENT
OF RIDGING AND HOW QUICKLY ARCTIC MOVES OUT BUT DID TREND TEMPERATURES
WARMER FOR FRIDAY AND SATURDAY. ANOTHER ARCTIC FRONT DROPS INTO
NORTHERN MONTANA SATURDAY NIGHT AND WENT WITH POPS SLIGHTLY ABOVE
CLIMO. EBERT
&&
.AVIATION...
LOW CLOUDS ARE BEGINNING TO LIFT AS COOL HIGH PRESSURE BUILDS IN
BEHIND THE NOW EXITING LOW PRESSURE SYSTEM. SCATTERED TO BROKEN
LOW CLOUDS WILL LINGER THIS EVENING WITH CEILINGS NEAR THE 3000 FT
VFR/MVFR THRESHOLD. EXPECT SOME AT LEAST PARTIAL CLEARING
OVERNIGHT...WHICH WILL ALLOW TEMPERATURES TO QUICKLY FALL AND
FROST TO FORM. NORTHWEST WINDS AROUND 10 KNOTS THIS EVENING WILL
BECOME LIGHT AND VARIABLE OVERNIGHT AND SOUTHWEST 5 TO 10 KNOTS
DURING THE DAY ON MONDAY.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1036 PM EST TUE DEC 6 2011
.SYNOPSIS...
DRIZZLE AND PATCHY FOG WILL BE OVER THE REGION OVERNIGHT, AS A
STORM SYSTEM SLOWLY PULLS EASTWARD. A STRONGER STORM WILL DEVELOP
IN THE MID ATLANTIC REGION WEDNESDAY AFTERNOON THEN TRACK
NORTHEAST ALONG THE COAST WEDNESDAY NIGHT. A RAIN AND SNOW MIX IS
LIKELY INITIALLY WEDNESDAY EVENING, THEN AS COLDER AIR GETS DRAWN
INTO THE SYSTEM A PERIOD OF SNOW IS LIKELY, WITH SEVERAL INCHES OF
SNOW POSSIBLE FOR THE WESTERN CATSKILLS AND POCONOS.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
THE FRONT IS ALONG OUR EXTREME EASTERN BORDER AT THIS HOUR.
TEMPERATURES REMAIN IN THE MID 50S OVER SULLIVAN COUNTY NY, WHILE
BROOME AND CHENANGO IS NOW IN THE UPPER 30S.
PATCHY DENSE FOG IS BEING OBSERVED, MAINLY ALONG THE HIGHER
ELEVATIONS. THE SURFACE OBS SHOW THAT THE DENSE FOG IS NOT
WIDESPREAD, SO WE WILL HOLD OFF ON A DENSE FOG ADVISORY.
SPOTTY DRIZZLE CONTINUES BEHIND THE FRONT. TEMPERATURES ARE
HOLDING IN THE MIDDLE TO UPPER 30S ACROSS OUR WESTERN AND CENTRAL
ZONES. LATEST RUC13 AND HRRR GUIDANCE SUGGESTS TEMPERATURES WILL
BARELY FALL OVERNIGHT, SO WE ARE NOT ANTICIPATING FREEZING
DRIZZLE. A FEW ISOLATED REPORTS ARE POSSIBLE...BUT THAT WOULD NOT
BE IN THE NEXT FEW HOURS.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
WEDNESDAY/WEDNESDAY NIGHT...UPPER LEVEL WAVE SHARPENS IN THE TN
VALLEY THEN MOVES INTO THE MID ATLANTIC REGION BY WEDNESDAY
EVENING. SFC LOW DEVELOPS IN RESPONSE TO THIS UPPER LEVEL WAVE
AND DEEPENS AS IT MOVES INTO THE MID ATLANTIC REGION BY WEDNESDAY
AFTERNOON. THIS FEATURE THEN TRACK NORTHEAST OFF THE SOUTHERN NJ
COAST AND INTO COASTAL NEW ENGLAND BY 12Z THURSDAY. MODEL TRENDS
HAVE BEEN TO TRACK SYSTEM FURTHER NORTH AND WEST LEADING TO MORE
PRECIP FOR FORECAST AREA. SNOW FORECAST VERY DIFFICULT WITH THIS
SYSTEM DUE TO FAST MOTION AND INITIALLY PRECIP WILL BE IN THE FORM
OF RAIN/SNOW THEN CHANGE TO ALL SNOW AS COLD AIR DEEPENS BEHIND
WAVE. FOR NOW IT LOOKS LIKE AND ADVISORY SNOWFALL FOR THE HIGHER
TERRAIN OF THE WESTERN CATSKILLS AND POCONOS WITH 3-5 INCHES
LIKELY. IF THE CONSENSUS TRACK CHANGES IT WILL HAVE A BIG IMPACT
ON TOTAL SNOW ACCUMS.
THURSDAY THROUGH FRIDAY...BEHIND THIS WAVE COLDER AIR WILL SPREAD
ACROSS CENTRAL NEW YORK WITH CONDITIONS MARGINAL FAVORABLE FOR
SOME LAKE EFFECT SNOW THURSDAY AFTERNOON THROUGH THURSDAY NIGHT.
WITH W/SW FLOW ACTIVITY WILL RESIDE MAINLY OVER NRN ONEIDA COUNTY
AND PARTS OF STEUBEN COUNTY AND THE FINGER LAKES REGION FROM LAKE ERIE.
ON FRIDAY THE NEXT UPPER LEVEL TROF WILL APPROACH THE REGION FROM
THE UPPER GREAT LAKES. WILL CONTINUE WITH CHC POPS FOR ALL BUT FAR
SE FA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
XNTDD PD BEGINS WITH A NW FLOW OF COLD AIR AND PSBL LE SNOW SHWRS
FOR MUCH OF THE AREA. THIS CONTS INTO SAT AS THE BASE OF THE UPR
TROF MVES THRU. GRADUAL WRM UP WITH DRIER AIR BEGINS LATE
SUN...BUT RDG IS FLAT AND WSW FLOW IS SLOW TO BRING HIER TEMPS TO
THE AREA. SOME LE MAY LINGER ACROSS THE NRN ZONES INTO SUN. WRMR
ON MON WITH THE SFC HI OFF TO THE EAST AND CONTD DRY WSW FLOW. H8
TEMPS CLIMB ABOVE 0C. COLD FNT ON TUES WILL BRING BACK THE PSBLTY
OF SOME LGT RAIN OR SNOW SHWRS...AND SOME WEAK LAKE ENHANCEMENT.
&&
.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
DFCLT AF FCST AS WEAK FLOW AND ABUNDANT MOISTURE RESULTS IN IFR
AND LIFR CONDS IN MANY PLACES. SOME TEMPORARY IMPRVMT PSBL AT
TIMES...BUT IN GNRL XPCT ONLY A VERY SLOW OVERALL IMPRVMT OVRNGT.
ON WED...WV MVG NE ALONG THE COLD FNT WILL BRING SOME MIXING AND
DRIER AIR IN FROM THE NORTH RESULTING IN IMPROVED CONDS. LATE IN
THE DAY...THIS SYTEM WILL PUSH RAIN AND LWRD CIGS AND VSBYS BACK
INTO AVP...AND PERHAPS SOME LGT SNOW TO BGM.
OUTLOOK...
WED AEVE - THU...VFR...XCPT AVP AND BGM MVFR/IFR IN RAIN AND SNOW.
FRI...MVFR SNOW SHWRS
SAT...VFR OCNL MVFR SNOW SHWRS.
SUN...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJP
NEAR TERM...DJP
SHORT TERM...RRM
LONG TERM...DGM
AVIATION...DGM
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
944 PM EST TUE DEC 6 2011
.SYNOPSIS...
MILD AND HUMID CONDITIONS WILL PREVAIL THROUGH WEDNESDAY AHEAD OF
A COLD FRONT. THE FRONT WILL BE PRECEDED BY SCATTERED TO NUMEROUS
SHOWERS AND ISOLATED THUNDERSTORMS...MAINLY WEDNESDAY AFTERNOON AND
EVENING. THE FRONT WILL MOVE OFF THE COAST WEDNESDAY EVENING...
ALLOWING COLD HIGH PRESSURE TO BUILD INTO THE AREA AND LINGER INTO
EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 944 PM TUESDAY...LATEST HRRR MODEL INDICATES POSSIBLE PCPN
ACROSS THE ADJACENT ATLANTIC WATERS LATE TONIGHT THAT COULD NIP THE
ILM COASTAL COUNTIES. TO ACCOMMODATE THIS POSSIBILITY...WILL
INDICATE LOW POPS FOR THE AREA AROUND AND INCLUDING CAPE FEAR. SW
FLOW ALOFT...AND SE-S FLOW AT THE LOWER LEVELS...WILL BOTH PROVIDE
THE NECESSARY MOISTURE FOR INCREASED CLOUD COVER. COULD SEE
WIDESPREAD 60S FOR TONIGHTS LOWS WHICH ARE THE NORMAL DAYTIME HIGHS
FOR THIS TIME OF THE YEAR...BIZARRE. FRONTAL DYNAMICS AND WEAK
IMPULSES OR S/W TROFS ALOFT RIDING NE ALONG IT...ARE PROGGED TO
REMAIN WEST OF THE ILM CWA OVERNIGHT. SOUTHERLY WINDS TO INCREASE
TONIGHT AHEAD OF THE FRONT...THUS PREVENTING ANY WIDESPREAD FOG
DEVELOPMENT.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 PM TUESDAY...A COLD FRONT WILL MOVE THROUGH THE AREA
WEDNESDAY AFTERNOON AND EVENING...BRINGING SCATTERED TO NUMEROUS
SHOWERS AND PERHAPS ISOLATED THUNDERSTORMS. THE GREATEST
POTENTIAL FOR PRECIPITATION LOOKS TO RUN FROM ABOUT 18Z THROUGH
ABOUT 03Z WITH WARM TEMPERATURES CONTINUING. AFTER THE FRONT PASSES
DURING THE EVENING...STRONG COLD AIR ADVECTION WILL
COMMENCE...USHERING IN A RETURN TO BELOW NORMAL TEMPERATURES FOR
THURSDAY AND THURSDAY NIGHT UNDER MAINLY CLEAR SKIES.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 300 PM TUESDAY...A RATHER DYNAMIC WEATHER PATTERN IS EXPECTED
TO UNFOLD THROUGH THE EXTENDED PERIOD WITH AT LEAST TWO UPPER-LEVEL
FEATURES EXPECTED TO BRING CLOUDS AND SOME CHANCES FOR RAIN.
EXTENDED-RANGE MODELS (GFS AND ECMWF) ARE IN GOOD AGREEMENT FRIDAY
AND SATURDAY...BUT THEN DIVERGE BEGINNING SUNDAY.
TWO ARCTIC HIGHS FRIDAY...ONE SITUATED EAST OF NEW ENGLAND AND A
SECOND OVER THE CENTRAL PLAINS STATES...WILL BE SEPARATED BY A
TROUGH/FRONT LYING JUST OFF THE CAROLINA COAST. AN UPPER LEVEL
DISTURBANCE STREAKING NORTHEAST FRIDAY EVENING WILL HELP INDUCE LOW
PRESSURE TO DEVELOP OFF THE COAST WITH A SHORT WINDOW FOR RAIN
POSSIBLE ALONG THE NC COAST AND OFFSHORE. OUR POP IS ONLY 20 PERCENT
AT ILM...WITH 10% POPS FARTHER WEST. AN ARCTIC COLD FRONT WILL PUSH
THROUGH THE AREA LATE FRIDAY NIGHT...FOLLOWED BY ARCTIC HIGH
PRESSURE BUILDING IN THROUGH MONDAY WITH MAINLY CLEAR SKIES. THE
ECMWF BEGINS TO DIVERGE FROM THE GFS HERE WITH ITS FORECAST POSITION
OF THE HIGH LYING A COUPLE HUNDRED MILES FARTHER SOUTH THAN THE GFS.
THE MAIN IMPLICATION HERE IS THAT A HIGH CENTERED CLOSER TO THE
CAROLINAS WOULD LIKELY GIVE US LIGHTER OVERNIGHT WIND SPEEDS AND
COLDER LOW TEMPERATURES SATURDAY AND SUNDAY NIGHTS.
MODELS DIVERGE FURTHER MONDAY INTO TUESDAY WITH THEIR HANDLING OF A
SHORTWAVE TROUGH MOVING NORTHEAST FROM TEXAS INTO THE CAROLINAS. THE
ECMWF DEVELOPS A LARGER AREA OF OVERRUNNING RAIN MONDAY INTO
TUESDAY...WHILE THE GFS REMAINS MUCH DRIER. THIS LIKELY DUE TO
DIFFERENCES IN DEGREE OF BACKING IN THE 850/700 MB FLOW...VERY
DIFFICULT TO DISCERN THIS FAR IN ADVANCE. WE HAVE INTRODUCED A 30
POP (RAIN) LATE MONDAY INTO TUESDAY ACKNOWLEDGING BETTER RUN-TO-RUN
CONSISTENCY IN THE ECMWF...BUT TEMPERED BY COLLABORATIVE THRESHOLDS
WITH SURROUNDING NWS OFFICES WHO ARE MAINTAINING A DRY FORECAST.
FORECAST TEMPERATURES THROUGH THE EXTENDED RANGE ARE GENERALLY A FEW
DEGREES WARMER IN THE ECMWF THAN IN THE GFS (WARMER 1000-500 MB
THICKNESSES AND WARMER 850 MB TEMPS). THE ONLY EXCEPTION MAY BE
SATURDAY AND SUNDAY NIGHTS WHERE THE FARTHER SOUTH POSITION OF THE
ARCTIC HIGH IN THE ECMWF COULD PRODUCE SOMEWHAT COOLER NIGHTTIME
LOWS THAN THE 12Z GFS INDICATES. OTHERWISE LATEST GFS MOS NUMBERS
ARE REASONABLE.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
AS OF 00Z...MODERATE CONFIDENCE OVERNIGHT WITH IFR STRATUS LIKELY
INLAND...POSSIBLE AT THE COAST. SHOWERS AND TSTMS WILL IMPACT THE
TERMINALS WEDNESDAY.
CAROLINAS REMAIN BETWEEN A COLD FRONT CRAWLING EASTWARD THROUGH THE
MTNS...AND HIGH PRESSURE RIDGING DOWN THE ATLANTIC SEA BOARD.
SIGNIFICANT DIFFERENCES BETWEEN LAST NIGHTS IFR FOG EVENT AND WHAT
IS EXPECTED TONIGHT LIES IN THE TIGHTER GRADIENT...AND HENCE
STRONGER WINDS...AND MORE WIDESPREAD CLOUD COVER.
DIURNAL CLOUD COVER WILL DISSIPATE SHORTLY...BUT MID LEVEL CLOUDS
BENEATH THE SUBSIDENCE INVERSION WILL PERSIST MUCH OF THE NIGHT.
EVEN SO...TWO DAYS OF E/SE FLOW HAS RAISED TD/S INTO THE LOW 60S
WHICH IS A CLEAR SIGNAL THIS TIME OF YEAR FOR FOG OR STRATUS.
TIGHTER PG AND A STRONGER LLJ INDICATES THAT DECOUPLING WILL NOT
OCCUR TONIGHT...SO WORST VSBYS WILL LIKELY BE MVFR.
HOWEVER...FORECAST SOUNDINGS AND THE HRRR...WHICH PERFORMED
REMARKABLY WELL LAST NIGHT...DEPICT WIDESPREAD LIFR STRATUS JUST
AWAY FROM THE COAST. HAVE INDICATED THIS IN TAFS AT LBT/FLO. AM NOT
TOO WORRIED ABOUT SEA STRATUS TONIGHT SINCE TD/S ARE BASICALLY THE
SAME AS THE WATER TEMPS...BUT HAVE INDICATED TEMPO IFR/LIFR STRATUS
AT ILM/CRE/MYR FOR PARTS OF THE OVERNIGHT. WILL MONITOR STRATUS
EVOLUTION AND UPDATE AS NECESSARY.
AFTER SUNRISE FOG/STRATUS WILL LIFT TO VFR AND COLD FRONT WILL BEGIN
TO IMPACT THE AREA FROM THE WEST IN THE AFTN. THE CONTINUALLY
TIGHTENING GRADIENT WILL PRODUCE WINDS FROM THE S/SW OF 10-15 KTS
GUSTING UP TO 25 KTS. SHOWERS WILL OVERSPREAD THE TERMINALS...FIRST
AT LBT/FLO BY LATE AFTN AND TO THE COAST DURING THE EVENING...AND
HAVE INDICATED CB AT THE INLAND TERMINALS WHERE SUFFICIENT
INSTABILITY IN SOUNDINGS SHOWS A POTENTIAL TSTM THREAT. PRECIP
INDUCED VSBYS AND CIGS OF AT LEAST MVFR ARE LIKELY...WITH IFR
POSSIBLE IN THE HEAVIEST RAIN.
EXTENDED OUTLOOK...SHOWERS LIKELY CONTINUING INTO THURSDAY WITH
MVFR/IFR. VFR THURSDAY EVE THROUGH SUNDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 944 PM TUESDAY...MODELS STILL INDICATING/PROGGING HIGHER WIND
SPEEDS ACROSS THE WATERS...WITH A REFLECTION WITH BUILDING SEAS.
OVERALL...MODELS THIS EARLY WINTER SEASON HAVE BEEN HAVING A
SOMEWHAT DIFFICULT TIME WITH OVER-FORECASTING WIND SPEEDS AND
BUILDING SEAS ACROSS THE ILM COASTAL WATERS IN THE WARM SECTOR AHEAD
OF APPROACHING STRONG COLD FRONTS. EXPECT SOME BLEEDING OF HIGHER
SEAS OFFSHORE INTO THE OUTER WATERS OF THE COASTAL WATERS...DUE TO
SSTS OFFSHORE IN THE 70S ALLOWING STRONGER WINDS ALOFT TO MIX TO THE
OCEAN SFC. S-SSW WINDS 10 TO 15 KT...AND SEAS 2 TO 4 FT...LIKELY
BUILDING TO 3 TO 5 FT...WITH THE HIGHER SEAS RESERVED ACROSS THE
OUTER WATERS. COULD OBSERVE SHRA OVER THE OFFSHORE WATERS TRACK INTO
THE COASTAL WATERS DURING THE OVERNIGHT PERIOD.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 PM TUESDAY...WINDS STEADILY INCREASE DURING THE DAY
WEDNESDAY FROM AROUND 20 KNOTS TO A RANGE OF 25-30 KNOTS BY
WEDNESDAY EVENING. GFS IS ADVERTISING 35 TO 40 KNOTS IN WAA BUT
WITH THE COOLER WATER TEMPERATURES...THIS LOOKS OVERDONE. THURSDAY
WILL SEE AN OFFSHORE FLOW THAT WEAKENS THROUGHOUT THE DAY. SEAS WILL
RAMP UP AS WELL WITH SOME EIGHT FOOTERS POSSIBLE LATE WEDNESDAY INTO
WEDNESDAY NIGHT BEFORE SUBSIDING TO 3 TO 4 FT THURSDAY AFTERNOON AND
EVENING. A SMALL CRAFT ADVISORY HAS BEEN RAISED FOR 18Z WEDNESDAY
THROUGH 12Z THURSDAY.
LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 300 PM TUESDAY...AN EXTENDED PERIOD OF MODERATE TO STRONG
NORTHEAST WINDS ARE EXPECTED THROUGH THE WEEKEND AS ARCTIC HIGH
PRESSURE BUILDS INTO THE REGION. AN INVERTED TROUGH OFF THE COAST
FRIDAY WILL BE KICKED FARTHER OFFSHORE AS AN ARCTIC COLD FRONT MOVES
THROUGH THE AREA SATURDAY MORNING. THE ARCTIC HIGH WILL MOVE NORTH
OF THE AREA THROUGH THE WEEKEND WITH STRONG MODERATE TO STRONG NORTH
TO NORTHEAST WINDS. THESE WINDS WILL BUILD SEAS TO AS MUCH AS 6-7
FEET IN THE OUTERMOST PORTIONS OF THE COASTAL WATERS SATURDAY NIGHT
INTO SUNDAY...WITH LESS AGITATED CONDITIONS EXPECTED CLOSER TO SHORE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 1 PM WEDNESDAY TO 8 AM EST
THURSDAY FOR AMZ250-252-254-256.
&&
$$
NEAR TERM...DCH
SHORT TERM...RAN
LONG TERM...TRA
AVIATION...JDW
AREA FORECAST DISCUSSION
NWS RALEIGH NC
121 AM EST MON DEC 5 2011
.SYNOPSIS...
CLOUD COVER AND CHANCES FOR RAIN WILL INCREASE OVER THE CAROLINAS
THROUGH MID WEEK IN ADVANCE OF A COLD FRONT APPROACHING FROM THE
WEST. THE COLD FRONT WILL PUSH OFFSHORE BY THURSDAY...WITH COOLER
AND DRIER CONDITIONS BY THE END OF THE WEEK.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 1000 PM SUNDAY...
THE PROBLEM OF THE NIGHT CONTINUES TO BE THE POTENTIAL FOR DENSE FOG
AND LOW STRATUS DEVELOPMENT.
1030+ MB SURFACE HIGH PRESSURE WAS LOCATED OFFSHORE OF THE
MID-ATLANTIC COAST WITH THE RIDGE AXIS EXTENDING SW DIRECTLY OVER
OUR REGION THIS EVENING. THE SURFACE WINDS WERE VERY LIGHT AND
MAINLY FROM THE NNE OVER OUR SE... WITH CALM CONDITIONS UNDER RIDGE
AXIS OVER OUR NW ZONES. THE LATEST SATELLITE DATA INDICATED
SCATTERED AREAS OF STRATOCUMULUS WITH BASES WELL UP AT 6500 FEET OR
SO. THE WV SATELLITE DATA INDICTED HIGH MOISTURE INCREASING ALOFT IN
THE BROAD SW FLOW WITH MOST OF THE PLUME OF MOISTURE AIMING WEST OF
THE APPALACHIANS.
THE LATEST HRRR INDICATES AN EXPLOSION OF FOG/LOW CLOUD DEVELOPMENT
OVER THE NORTHERN COASTAL PLAIN SHORTLY... THEN EXPANDING/DEVELOPING
WESTWARD INTO THE NORTHERN AND EASTERN PIEDMONT BETWEEN 08Z-12Z.
SURFACE OBSERVATIONS WERE ALREADY INDICATING THIS PROCESS WAS
BEGINNING OVER SE VA AND NE NC. THE VERTICAL MOISTURE/WIND PROFILES
OVER THE NORTHEAST AND NORTH CENTRAL NC ZONES ARE MOST FAVORABLE FOR
THE DENSE FOG AND LOW STRATUS. WE WILL GO WITH THE LATEST HRRR
FORECAST WHICH HAS STRONG SUPPORT FROM THE LATEST NAM... AND CURRENT
ANALYZED DATA. NO OTHER CHANGES ARE NEEDED AT THIS TIME. -BADGETT
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
AS OF 242 PM SUNDAY...
MONDAY:
SLOW MOVING FRONTAL ZONE ASSOCIATED WITH THE FULL LATITUDE TROUGH
ALOFT TO THE WEST OF THE AREA WILL REMAIN WEST OF THE MOUNTAINS ON
MONDAY. AFTERNOON LOW LEVEL THICKNESS VALUES ARE EXPECTED TO
INCREASE A GOOD 15 METERS OR SO FROM TODAY. HOWEVER... INCREASE IN
AFOREMENTIONED MOISTURE AND CLOUD COVER WILL HELP OFFSET THE
INCREASE IN LOW LEVEL THICKNESS VALUES... AS SKIES WILL ONLY IMPROVE
INTO THE PARTLY SUNNY TO MOSTLY CLOUDY RANGE (MORE IMPROVEMENT
SOUTHEAST/EAST VS NORTHWEST). THUS... EXPECT TEMPS WILL BE SIMILAR
TO TODAYS VALUES... MAYBE A BIT WARMER ACROSS THE SOUTHEAST. THIS
YIELDS HIGH TEMPS RANGING FROM AROUND 60 IN THE NORTHWEST TO NEAR 70
IN THE SOUTHEAST. IN ADDITION... CANNOT RULE OUT A FEW WAA SHOWERS
OR SPRINKLES MAINLY ACROSS THE WEST/NORTHWEST (UPSLOPE FLOW).
HOWEVER... WITH A LOT OF DRY AIR ALOFT AND AMOUNT OF MOISTURE AND
LIFT QUITE SHALLOW WILL GO WITH A DRY FORECAST.
MONDAY NIGHT THROUGH TUESDAY NIGHT...SURFACE RIDGE OVER THE FORECAST
AREA GRADUALLY WEAKENS AND SHIFTS EWD MONDAY NIGHT THROUGH TUESDAY.
THIS WILL ALLOW A SURFACE COLD FRONT ASSOCIATED WITH POSITIVELY TILT
UPPER TROUGH (EXTENDING FROM THE GREAT LAKES INTO THE SOUTHERN
ROCKIES) TO EDGE EAST...POSSIBLY ENTERING THE NC MOUNTAINS TUESDAY
MORNING. RETURN FLOW ON THE BACKSIDE OF THE HIGH WILL ADVECT LOW
LEVEL MOISTURE INTO CENTRAL NC. RH CROSS SECTIONS SUGGEST MOISTURE
MAINLY CONFINED TO THE LOWEST 5000FT WITH A DECENT LAYER OF DRY AIR
IN THE MID LAYERS OF THE ATMOSPHERE. BEST ISENTROPIC LIFT IN THE
295-300K LAYER OCCURRING NEAR OUR WESTERN PERIPHERY. WHILE COULD SEE
A FEW SPRINKLES ALONG AND EAST OF HIGHWAY 1...BETTER POTENTIAL FOR
MEASURABLE LIGHT PRECIP WILL BE OVER OUR WESTERN COUNTIES...MAINLY
AFTER MIDNIGHT (LIKELY CLOSER TO DAYBREAK). HAVE ADJUSTED POPS
MONDAY NIGHT...KEEPING THE EVENING HOURS DRY THEN LIMITING SLIGHT
CHANCE POPS TO THE WESTERN THIRD OF THE REGION.
BEST CHANCE FOR LIGHT PRECIP AMOUNTS TUESDAY-TUESDAY NIGHT WILL
REMAIN IN VICINITY OF THE SURFACE BOUNDARY THAT WILL INCH E-SE
TOWARD THE NW COUNTIES DURING THIS PERIOD AS DEEP SW FLOW AND
STUBBORN HIGH OFFSHORE WILL RESULT IN LITTLE PUSH TO THIS FEATURE.
THUS...POPS ACROSS CENTRAL NC WILL GRADUATE FROM SOLID CHANCE FAR
N-NW TO SMALL CHANCE SE. MAY SEE A PERIOD WHERE PRECIP ACROSS THE N
AND NW LIMITED/NON-EXISTENT BUT DIFFICULT TO DETERMINE THIS FAR OUT
WHEN THIS WILL OCCUR. PRECIP AMOUNTS TUESDAY INTO TUESDAY NIGHT
SHOULD REMAIN LIGHT (LESS THAN A QUARTER OF INCH MOST LOCALES WITH
JUST A FEW HUNDREDTHS PROBABLE IN THE SE) AS LIFT FOR PRECIP
GENERATION RELATIVELY WEAK.
TEMPS MONDAY NIGHT THROUGH TUESDAY NIGHT SHOULD REMAIN MILD FOR THIS
TIME OF YEAR... AND MAINLY DEPENDENT ON THE AMOUNT OF PRECIP
COVERAGE OVER THE NW. MIN TEMPS LOW-MID 50S. HIGH TEMPS TUESDAY MID
60S NW TO AROUND 70/LOWER 70S SE.
WEDNESDAY AND WEDNESDAY NIGHT...
FORECAST CONFIDENCE LOWER THAN NORMAL BEGINNING THIS PERIOD AS
MEDIUM RANGE GUIDANCE DIFFER QUITE A BIT WITH EASTWARD TRANSLATION
OF ENERGY IN THE SOUTHERN STREAM. THE ECMWF-GFS DIFFERENCE LAST
NIGHT WAS ABOUT 12HRS FROM EACH OTHER (GFS SLOWER). LATEST 12Z MODEL
RUNS SUGGEST A DIFFERENCE OF ABOUT 6-8 HOURS WITH THE GFS SPEEDING
THINGS UP A BIT FROM ITS 06Z RUN. 12Z ECMWF DISPLAY A BIT MORE
CONSISTENCY BUT STILL SOME QUESTIONS ON ITS HANDLING OF THE S/W AND
POTENTIAL SURFACE CYCLOGENESIS JUST S-SE OF OUR REGION.
MODELS DO AGREE THAT S/W IN THE SOUTHERN STREAM WILL START OUT
FAIRLY POTENT THEN WEAKEN AS IT ENCOUNTERS INCREASING CONFLUENCE
ALOFT AS IT TRANSLATE EWD ACROSS THE DEEP SOUTH AND SE U.S LATE
WED-THU. GFS AND ECMWF SUGGEST CYCLOGENESIS OCCURRING LATE WED NIGHT
INTO THU THOUGH GFS FARTHER INLAND (OVER THE FOOTHILLS OF NC) WHILE
ECMWF FAVORS A SOLUTION CLOSER TO THE COAST. THIS WILL HAVE
IMPLICATION ON TEMPS WED AND MORE SO WED NIGHT AS WELL AS CHARACTER
OF PRECIP AS ECMWF FAVORS WIDESPREAD RAIN IN AN OVERRUNNING EVENT
WHILE GFS WOULD SUGGEST PRECIP MORE CONVECTIVE IN NATURE (HIGH
SHEAR/LOW INSTABILITY SCENARIO). STILL...APPEARS HIGHEST THREAT FOR
PRECIP ACROSS CENTRAL NC WILL OCCUR LATE WED INTO THU MORNING...WITH
MOST GUIDANCE FAVORING WED NIGHT.
FOR NOW WILL MAINTAIN PREVIOUS FORECAST OF HIGHER POPS NW VERSUS SE
WED BUT FAVOR HIGHEST POPS ACROSS THE REGION WED NIGHT RATHER THAN
WED. THUS WILL INCREASE POPS TO LIKELY ACROSS THE REGION WED NIGHT
INTO THU AM IN THE EAST. TEMPS WED-WED NIGHT HIGHLY DEPENDENT ON
EVENTUAL PASSAGE/POSITION OF THE SURFACE BOUNDARY. ECMWF WOULD
FAVOR COOLER MIN TEMPS WED NIGHT THAN CURRENTLY ADVERTISED (BY ABOUT
3-4 DEGREES). HOWEVER IF GFS MORE CORRECT...MIN TEMPS WED NIGHT MAY
BE AS MUCH AS 10 DEGREES WARMER THAN FORECAST....ESPECIALLY SE HALF.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 242 PM SUNDAY...
THIS PERIOD STARTS OUT ACTIVE THAN TRANSITIONS TO A COOL DRY WEATHER
SCENARIO FOR THE WEEKEND.
S/W AND ASSOCIATED SURFACE BOUNDARY EXPECTED TO DEPART OUR REGION
THURSDAY. GFS MAINTAINS DECENT CHANCE FOR PRECIP ACROSS THE EASTERN
HALF THROUGH THU AFTERNOON WHILE ECMWF (FASTER THAN GFS) WOULD END
THE PRECIP IN THE EAST PRIOR TO THU AFTERNOON. WILL ADVERTISE POPS
DECREASING WEST-TO EAST THU THOUGH MAINTAIN SMALL CHANCE POP IN THE
EAST UNTIL SUNSET (WORST CASE SCENARIO). EXPECT DECENT CAA IN THE
WAKE OF THE DEPARTING SYSTEM SO TEMPS THU MAY ONLY RECOVER 7-10
DEGREES FROM MORNING LOWS.
STABLE COOL CANADIAN HIGH WILL BUILD INTO AND SETTLE OVER THE SE
U.S. FRI INTO SUN. NORTHERN BRANCH OF WESTERLIES CURRENTLY EXPECTED
TO BE MORE ACTIVE COMPARED TO THE SOUTHERN STREAM SO BULK OF STORM
ACTIVITY WILL OCCUR WELL TO OUR N-NW. THUS EXPECT MAINLY DRY
CONDITIONS THU NIGHT THROUGH SUNDAY. PRESENCE OF BROAD L/W TROUGH
OVER THE REGION AND SURFACE HIGH OF CANADIAN ORIGIN BUILDING INTO
THE REGION SUPPORTS TEMPS SLIGHTLY BELOW NORMAL.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS OF 120 AM MONDAY...
24-HR TAF PERIOD:
LOWER THAN NORMAL CONFIDENCE THROUGH THE TAF PERIOD. THE LATEST
(00Z) GFS/NAM FCST SOUNDINGS ARE FAILING TO CAPTURE BKN060-OVC060
CEILINGS CURRENTLY PRESENT OVER MOST OR ALL OF CENTRAL NC AS OF 05Z
THIS MORNING. INSTEAD...FCST SOUNDINGS SHOW SATURATION IN THE LOWEST
LEVELS (SURFACE TO 500 FT AGL) BY 06Z ACROSS THE ENTIRE AREA...
SOMETHING THAT OBSERVATIONS DO NOT REFLECT ANYWHERE OVER OR UPSTREAM
OF THE AREA WITH THE EXCEPTION OF FAR SOUTHEAST VA. AS A RESULT...IT
IS DIFFICULT TO BELIEVE FCST SOUNDINGS SHOWING IFR/LIFR CONDITIONS
IN FOG/LOW STRATUS DEVELOPING PRIOR TO SUNRISE. WITH THIS IN MIND...
WILL REVERSE COURSE ON THE PREVIOUS TAF FORECAST AND HAVE OPTED TO
ONLY SHOW A TEMPO GROUP FOR MVFR CEILINGS/VISBYS PRIOR TO 12Z THIS
MORNING. WILL INDICATE MVFR CEILINGS EVERYWHERE FROM SUNRISE-SUNSET
TODAY GIVEN THAT THE BOUNDARY LAYER SHOULD CONTINUE TO MOISTEN VIA A
PERSISTENT AND STRENGTHENING SOUTHEASTERLY RETURN FLOW IN THE LOWER
LEVELS. PATCHY LIGHT RAIN/SPRINKLES (AND LOCALLY LOWER CEILINGS/
VISBYS) WILL BE POSSIBLE EVERYWHERE THIS AFTERNOON INTO TONIGHT...
WITH THE RELATIVE BEST CHANCE AT THE INT/GSO TAF SITES...HOWEVER...
CONFIDENCE IN THE EXACT LOCATION OF SAID ACTIVITY IS LOW ENOUGH TO
PRECLUDE MENTIONING AT THIS TIME. WARM ADVECTION WILL FURTHER
STRENGTHEN TONIGHT...AND ANTICIPATE A BETTER CHANCE FOR IFR AND
PERHAPS LIFR CONDITIONS DEVELOPING BY THE END OF THE TAF PERIOD...IN
THE 06-12Z TIME FRAME TUE MORNING. EXPECT LIGHT/VARIABLE OR CALM
WINDS THIS MORNING BECOMING SSE AT ~5 KT THIS AFTERNOON THROUGH THE
REMAINDER OF THE TAF PERIOD.
LOOKING AHEAD:
A COLD FRONT WILL SLOWLY APPROACH THE CAROLINAS FROM THE WEST ON
TUESDAY...MOVING INTO AND PERHAPS STALLING OVER THE AREA TUE
NIGHT/WED. AN UPPER LEVEL DISTURBANCE APPROACHING THE CAROLINAS FROM
THE WEST WED AND CROSSING THE AREA WED NIGHT WILL ENHANCE PRECIP
CHANCES ALONG THE FRONT BEFORE PUSHING IT OFFSHORE WED NIGHT/THU
MORNING. A PROLONGED PERIOD OF SUB-VFR CONDITIONS OVER ALL OR
PORTIONS OF THE AREA IS LIKELY TUE INTO WED...WITH THE BEST CHANCE
FOR WIDESPREAD RAIN AND IFR/LIFR CONDITIONS WED AFTERNOON THROUGH
WED NIGHT. EXPECT VFR CONDITIONS TO RETURN IN THE WAKE OF THE FRONT
THU/FRI. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...BADGETT
SHORT TERM...BSD/WSS
LONG TERM...WSS
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1253 AM EST MON DEC 5 2011
.SYNOPSIS...
WITH HIGH PRESSURE EAST OF THE REGION OUR ATTENTION TURNS TO A
SLOW MOVING FRONTAL SYSTEM APPROACHING PENNSYLVANIA. CLOUDS FROM
THIS FRONT WILL GRADUALLY OVERSPREAD THE REGION LATE TONIGHT AND
MONDAY MORNING. FOR THE MIDDAY AND AFTERNOON HOURS ON MONDAY
RAINFALL WILL INCREASE IN COVERAGE AND INTENSITY OVER THE WEST AND
SPREAD ACROSS CENTRAL PENNSYLVANIA MONDAY NIGHT. TEMPERATURES WILL
CONTINUE WELL ABOVE AVERAGE WITH THIS SYSTEM...UNTIL A STRONG COLD
FRONT BRING TEMPERATURES BACK DOWN TO AVERAGE READINGS LATE
TUESDAY AND WEDNESDAY. ANOTHER STORM SYSTEM WILL APPROACH THE
REGION FROM THE SOUTH ON THURSDAY. THIS STORM HAS THE POTENTIAL TO
BRING SOME WINTRY OR MIXED PRECIPITATION DEPENDING ON THE TRACK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
FOR THE 1230AM UPDATE...ADDED MENTION OF PATCHY DENSE FOG ACRS
MUCH OF THE LWR SUSQ VLY. IR SATL/SFC OBS/SPOTTER REPORTS CONFIRM
LCL VIS NEAR 0SM IN SPOTS. WILL COVER WITH SPS FOR NOW AND
CONTINUE TO MONITOR FOR POSSIBLE DENSE FOG HEADLINE. ALSO CUT-BACK
ON POP CVRG BASED ON RDR IN THE NW MTNS.
PREVIOUS DISCUSSION...
TRANQUIL WEATHER WILL PERSIST OVERNIGHT ACROSS MOST OF THE REGION
WITH JUST AREAS OF MAINLY CIRROSTRATUS...AND SOME HIGH-BASED ALTO
CU DRIFTING NE.
15Z SREF...18Z NAM AND 00Z RUC SHOWS SOME LIGHT SHOWERS PUSHING
INTO WARREN AND WRN MCKEAN COUNTY TONIGHT /AND PERHAPS ELK COUNTY
AFTER 07Z/. QPF WILL BE LIGHT AND LESS THAN 0.10 OF AN INCH
THROUGH DAYBREAK MONDAY.
THE SHOWERS WILL BE AT THE EASTERN EDGE OF A NNE/SSW RIBBON OF 1
INCH PWAT AIR. A RATHER SHARP GRADIENT TO LOWER...MEAN 925-850 MB
THETA-E AIR WILL OCCUR NEAR THE ALLEGHENY FRONT THOUGH 12Z MONDAY
WITH POPS AOB 10 PERCENT ACROSS OUR CENTRAL AND ERN ZONES.
RELATIVELY HIGHER SFC DEWPOINTS ACROSS THE SUSQ VALLEY AS SOME
PERIODS OF CLEARING WILL SUPPORT THE FORMATION OF FOG/LOW CLOUDS
ONCE AGAIN LATE TONIGHT. NUMERICAL/MOS GUIDANCE INDICATES UP TO A
SVRL HOUR PERIOD OF VSBYS BELOW 1SM AT KLNS...KMDT AND KTHV TOWARD
DAYBREAK. INCLUDED AREAS OF FOG WITH PATCHY DENSE FOG WITH THIS
LATEST GRID UPDATE - ACROSS THE MIDDLE SUSQ...AND ESP LOWER SUSQ
VALLEY LATE TONIGHT/EARLY MONDAY.
VERY MILD TEMPS FOR EARLY DECEMBER WILL CONTINUE THROUGH TONIGHT.
THANKS TO THE GENERALLY LIGHT SOUTHERLY BREEZE...AND FAIR AMOUNT
OF CLOUD COVER...TEMPS WILL ONLY REACH THE UPPER 30S TO LOWER 40S
FOR MINS IN MOST PLACES /WHICH WILL BE 10-15F ABOVE NORMAL...WITH
THE GREATEST DEPARTURES OCCURRING ACROSS THE MOUNTAINS/. THE
TYPICALLY COLDER SPOTS NEAR AND TO THE EAST OF THE SUSQ VALLEY
/LIKE KTHV AND KSEG/ WILL DIP INTO THE LOWER AND MID 30S WITH NEAR
CALM AIR.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
CLOUDS LOWER AND THICKEN AS FRONTAL BOUNDARY APPROACHES.
PRECIPITATION WILL INCREASE IN THE AFTERNOON HOURS AND BECOME A
STEADY LIGHT RAIN OVERNIGHT. FRONT STILL WEST OF AREA SO MILD
TEMPERATURES CONTINUE THROUGH THE PERIOD.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
MODELS AGREE ON A COLD FRONT PUSHING ACROSS PA ON TUE...KEEPING
RAIN CHANCES HIGH...ESPECIALLY ACROSS THE SOUTHERN MTNS AND SUSQ
VALLEY. TEMPS TUE START OFF MILD...BUT WILL LIKELY REMAIN STEADY
OR FALL A BIT IN THE AFTERNOON...ESP IN THE NW. NO LARGE PUSH OF
COLD AIR BEHIND FRONT EVIDENT THOUGH.
LINGERING CHANCE FOR LIGHT RAIN/SNOW SHOWERS TUE NIGHT INTO WED AS
NARROW TROUGH AND COOLER AIR SLIDES OVERHEAD.
MUCH UNCERTAINTY IN LATE WEEK SOLUTIONS AS LARGE MODEL DIVERGENCE
CONTINUES. WAVE OF LOW PRESSURE SLIDES UP/EAST OF THE APPALACHIANS
THU...WITH ECMWF CONTINUING TO TRACK THIS TO OUR SE...THOUGH THE
GFS SOLUTION CONTINUES TO BECOME GRADUALLY MORE INTERESTING WITH A
MORE NORTHERLY TRACK. TOUGH TO RESOLVE THIS IN THE GRIDS OTHER
THAN TO EDGE POPS UPWARD A BIT ON THU AND SEE HOW THIS PLAYS OUT.
COULD BRING POTENTIAL FOR 0.50 INCH QPF...WITH SOME OF THAT
FALLING AS SNOW IF THE GFS SOLUTION WINS OUT...THOUGH AM STILL
LEANING MORE TOWARD THE ECMWF SOLUTION AT THIS TIME.
TROUGH DIGS IN FROM THE NW FRI NIGHT INTO SAT...BRINGING NOTICEABLY
COLDER TEMPS AND WESTERLY FLOW. THIS WILL ALSO BRING A GOOD CHANCE
FOR LAKE EFFECT SNOW SHOWERS IN THE NW MTNS SAT. TEMPS SHOULD
BEGIN TO REBOUND EARLY NEXT WEEK.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
LIGHT WINDS AND MCLEAR SKIES ARE ALLOWING RADIATIONAL FOG TO FORM
ACROSS EASTERN PA LATE THIS EVENING. 04Z OBS SHOWING LIFR CONDS IN
LOW CLOUDS/FOG OVERSPREADING SOUTHEAST PA. ADDITIONAL COOLING
OVERNIGHT SHOULD ALLOW THE FOG TO BECOME THICKER AND SPREAD WEST
AND NORTHWARD INTO THE SUSQ VALLEY. BULK OF LATEST SHORT RANGE MDL
DATA SUGGESTS IFR VSBYS ARE POSSIBLE LATE TONIGHT AT MDT/IPT.
CURRENTLY IFR TO LIFR VSBYS AT LNS WILL CONTINUE UNTIL 15Z.
FOG OVER THE SUSQ VALLEY SHOULD DISSIPATE BY MIDDAY MONDAY. FOCUS
WILL THEN SHIFT TOWARD APPROACHING COLD FRONT...WHICH WILL SPREAD
SHRA INTO THE NW MTNS DURING THE AFTN. IFR CIGS/VSBYS APPEAR
POSSIBLE AT BFD BY MONDAY EVENING. DETERIORATING CONDS SHOULD
SPREAD ACROSS THE REST OF CENTRAL PA MONDAY NIGHT WITH THE ARRIVAL
OF THE FRONT.
OUTLOOK...
TUE...AM LOW CIGS POSSIBLE.
WED...NO SIG WX EXPECTED.
THU...RAIN/SNOWLOW CIGS POSSIBLE.
FRI...SHSN POSSIBLE W MTNS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...ROSS/LAMBERT
NEAR TERM...LAMBERT/STEINBUGL
SHORT TERM...ROSS/LAMBERT
LONG TERM...RXR
AVIATION...FITZGERALD/CERU
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1222 AM EST MON DEC 5 2011
.SYNOPSIS...
WITH HIGH PRESSURE EAST OF THE REGION OUR ATTENTION TURNS TO A
SLOW MOVING FRONTAL SYSTEM APPROACHING PENNSYLVANIA. CLOUDS FROM
THIS FRONT WILL GRADUALLY OVERSPREAD THE REGION LATE TONIGHT AND
MONDAY MORNING. FOR THE MIDDAY AND AFTERNOON HOURS ON MONDAY
RAINFALL WILL INCREASE IN COVERAGE AND INTENSITY OVER THE WEST AND
SPREAD ACROSS CENTRAL PENNSYLVANIA MONDAY NIGHT. TEMPERATURES WILL
CONTINUE WELL ABOVE AVERAGE WITH THIS SYSTEM...UNTIL A STRONG COLD
FRONT BRING TEMPERATURES BACK DOWN TO AVERAGE READINGS LATE
TUESDAY AND WEDNESDAY. ANOTHER STORM SYSTEM WILL APPROACH THE
REGION FROM THE SOUTH ON THURSDAY. THIS STORM HAS THE POTENTIAL TO
BRING SOME WINTRY OR MIXED PRECIPITATION DEPENDING ON THE TRACK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
FOR THE 1230AM UPDATE...ADDED MENTION OF PATCHY DENSE FOG ACRS
MUCH OF THE LWR SUSQ VLY. IR SATL/SFC OBS/SPOTTER REPORTS CONFIRM
LCL VIS NEAR 0SM IN SPOTS. WILL COVER WITH SPS FOR NOW AND
CONTINUE TO MONITOR FOR POSSIBLE DENSE FOG HEADLINE. ALSO CUT-BACK
ON POP CVRG BASED ON RDR IN THE NW MTNS.
PREVIOUS DISCUSSION...
TRANQUIL WEATHER WILL PERSIST OVERNIGHT ACROSS MOST OF THE REGION
WITH JUST AREAS OF MAINLY CIRROSTRATUS...AND SOME HIGH-BASED ALTO
CU DRIFTING NE.
15Z SREF...18Z NAM AND 00Z RUC SHOWS SOME LIGHT SHOWERS PUSHING
INTO WARREN AND WRN MCKEAN COUNTY TONIGHT /AND PERHAPS ELK COUNTY
AFTER 07Z/. QPF WILL BE LIGHT AND LESS THAN 0.10 OF AN INCH
THROUGH DAYBREAK MONDAY.
THE SHOWERS WILL BE AT THE EASTERN EDGE OF A NNE/SSW RIBBON OF 1
INCH PWAT AIR. A RATHER SHARP GRADIENT TO LOWER...MEAN 925-850 MB
THETA-E AIR WILL OCCUR NEAR THE ALLEGHENY FRONT THOUGH 12Z MONDAY
WITH POPS AOB 10 PERCENT ACROSS OUR CENTRAL AND ERN ZONES.
RELATIVELY HIGHER SFC DEWPOINTS ACROSS THE SUSQ VALLEY AS SOME
PERIODS OF CLEARING WILL SUPPORT THE FORMATION OF FOG/LOW CLOUDS
ONCE AGAIN LATE TONIGHT. NUMERICAL/MOS GUIDANCE INDICATES UP TO A
SVRL HOUR PERIOD OF VSBYS BELOW 1SM AT KLNS...KMDT AND KTHV TOWARD
DAYBREAK. INCLUDED AREAS OF FOG WITH PATCHY DENSE FOG WITH THIS
LATEST GRID UPDATE - ACROSS THE MIDDLE SUSQ...AND ESP LOWER SUSQ
VALLEY LATE TONIGHT/EARLY MONDAY.
VERY MILD TEMPS FOR EARLY DECEMBER WILL CONTINUE THROUGH TONIGHT.
THANKS TO THE GENERALLY LIGHT SOUTHERLY BREEZE...AND FAIR AMOUNT
OF CLOUD COVER...TEMPS WILL ONLY REACH THE UPPER 30S TO LOWER 40S
FOR MINS IN MOST PLACES /WHICH WILL BE 10-15F ABOVE NORMAL...WITH
THE GREATEST DEPARTURES OCCURRING ACROSS THE MOUNTAINS/. THE
TYPICALLY COLDER SPOTS NEAR AND TO THE EAST OF THE SUSQ VALLEY
/LIKE KTHV AND KSEG/ WILL DIP INTO THE LOWER AND MID 30S WITH NEAR
CALM AIR.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
CLOUDS LOWER AND THICKEN AS FRONTAL BOUNDARY APPROACHES.
PRECIPITATION WILL INCREASE IN THE AFTERNOON HOURS AND BECOME A
STEADY LIGHT RAIN OVERNIGHT. FRONT STILL WEST OF AREA SO MILD
TEMPERATURES CONTINUE THROUGH THE PERIOD.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
MODELS AGREE ON A COLD FRONT PUSHING ACROSS PA ON TUE...KEEPING
RAIN CHANCES HIGH...ESPECIALLY ACROSS THE SOUTHERN MTNS AND SUSQ
VALLEY. TEMPS TUE START OFF MILD...BUT WILL LIKELY REMAIN STEADY
OR FALL A BIT IN THE AFTERNOON...ESP IN THE NW. NO LARGE PUSH OF
COLD AIR BEHIND FRONT EVIDENT THOUGH.
LINGERING CHANCE FOR LIGHT RAIN/SNOW SHOWERS TUE NIGHT INTO WED AS
NARROW TROUGH AND COOLER AIR SLIDES OVERHEAD.
MUCH UNCERTAINTY IN LATE WEEK SOLUTIONS AS LARGE MODEL DIVERGENCE
CONTINUES. WAVE OF LOW PRESSURE SLIDES UP/EAST OF THE APPALACHIANS
THU...WITH ECMWF CONTINUING TO TRACK THIS TO OUR SE...THOUGH THE
GFS SOLUTION CONTINUES TO BECOME GRADUALLY MORE INTERESTING WITH A
MORE NORTHERLY TRACK. TOUGH TO RESOLVE THIS IN THE GRIDS OTHER
THAN TO EDGE POPS UPWARD A BIT ON THU AND SEE HOW THIS PLAYS OUT.
COULD BRING POTENTIAL FOR 0.50 INCH QPF...WITH SOME OF THAT
FALLING AS SNOW IF THE GFS SOLUTION WINS OUT...THOUGH AM STILL
LEANING MORE TOWARD THE ECMWF SOLUTION AT THIS TIME.
TROUGH DIGS IN FROM THE NW FRI NIGHT INTO SAT...BRINGING NOTICEABLY
COLDER TEMPS AND WESTERLY FLOW. THIS WILL ALSO BRING A GOOD CHANCE
FOR LAKE EFFECT SNOW SHOWERS IN THE NW MTNS SAT. TEMPS SHOULD
BEGIN TO REBOUND EARLY NEXT WEEK.
&&
.AVIATION /05Z MONDAY THROUGH FRIDAY/...
A LIGHT WIND AND MCLEAR SKIES ALLOWING RADIATION FOG TO FORM
ACROSS EASTERN PA LATE THIS EVENING. 04Z OBS SHOWING IFR CONDS IN
LOW CLOUDS/FOG OVERSPREADING SOUTHEAST PA. ADDITIONAL COOLING
OVERNIGHT SHOULD ALLOW THE FOG TO BECOME THICKER AND SPREAD
WESTWARD INTO THE SUSQ VALLEY. BULK OF LATEST SHORT RANGE MDL
DATA SUGGESTS IFR VSBYS ARE POSSIBLE LATE TONIGHT AT MDT/IPT AND
VERY LIKELY AT LNS.
FOG OVER THE SUSQ VALLEY SHOULD DISSIPATE BY MIDDAY MONDAY. FOCUS
WILL THEN SHIFT TOWARD APPROACHING COLD FRONT...WHICH WILL SPREAD
SHRA INTO THE NW MTNS DURING THE AFTN. IFR CIGS/VSBYS APPEAR
POSSIBLE AT BFD BY MON EVENING...AND DETERIORATING CONDS SHOULD
SPREAD ACROSS THE REST OF CENTRAL PA MON NITE WITH ARRIVAL OF
FRONT.
OUTLOOK...
TUE...AM LOW CIGS POSSIBLE.
WED...NO SIG WX EXPECTED.
THU...RAIN/SNOWLOW CIGS POSSIBLE.
FRI...SHSN POSSIBLE W MTNS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...ROSS/LAMBERT
NEAR TERM...LAMBERT/STEINBUGL
SHORT TERM...ROSS/LAMBERT
LONG TERM...RXR
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1140 PM EST SUN DEC 4 2011
.SYNOPSIS...
WITH HIGH PRESSURE EAST OF THE REGION OUR ATTENTION TURNS TO A
SLOW MOVING FRONTAL SYSTEM APPROACHING PENNSYLVANIA. CLOUDS FROM
THIS FRONT WILL GRADUALLY OVERSPREAD THE REGION LATE TONIGHT AND
MONDAY MORNING. FOR THE MIDDAY AND AFTERNOON HOURS ON MONDAY
RAINFALL WILL INCREASE IN COVERAGE AND INTENSITY OVER THE WEST AND
SPREAD ACROSS CENTRAL PENNSYLVANIA MONDAY NIGHT. TEMPERATURES WILL
CONTINUE WELL ABOVE AVERAGE WITH THIS SYSTEM...UNTIL A STRONG COLD
FRONT BRING TEMPERATURES BACK DOWN TO AVERAGE READINGS LATE
TUESDAY AND WEDNESDAY. ANOTHER STORM SYSTEM WILL APPROACH THE
REGION FROM THE SOUTH ON THURSDAY. THIS STORM HAS THE POTENTIAL TO
BRING SOME WINTRY OR MIXED PRECIPITATION DEPENDING ON THE TRACK.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
TRANQUIL WEATHER WILL PERSIST OVERNIGHT ACROSS MOST OF THE REGION
WITH JUST AREAS OF MAINLY CIRROSTRATUS...AND SOME HIGH-BASED ALTO
CU DRIFTING NE.
15Z SREF...18Z NAM AND 00Z RUC SHOWS SOME LIGHT SHOWERS PUSHING
INTO WARREN AND WRN MCKEAN COUNTY TONIGHT /AND PERHAPS ELK COUNTY
AFTER 07Z/. QPF WILL BE LIGHT AND LESS THAN 0.10 OF AN INCH
THROUGH DAYBREAK MONDAY.
THE SHOWERS WILL BE AT THE EASTERN EDGE OF A NNE/SSW RIBBON OF 1
INCH PWAT AIR. A RATHER SHARP GRADIENT TO LOWER...MEAN 925-850 MB
THETA-E AIR WILL OCCUR NEAR THE ALLEGHENY FRONT THOUGH 12Z MONDAY
WITH POPS AOB 10 PERCENT ACROSS OUR CENTRAL AND ERN ZONES.
RELATIVELY HIGHER SFC DEWPOINTS ACROSS THE SUSQ VALLEY AS SOME
PERIODS OF CLEARING WILL SUPPORT THE FORMATION OF FOG/LOW CLOUDS
ONCE AGAIN LATE TONIGHT. NUMERICAL/MOS GUIDANCE INDICATES UP TO A
SVRL HOUR PERIOD OF VSBYS BELOW 1SM AT KLNS...KMDT AND KTHV TOWARD
DAYBREAK. INCLUDED AREAS OF FOG WITH PATCHY DENSE FOG WITH THIS
LATEST GRID UPDATE - ACROSS THE MIDDLE SUSQ...AND ESP LOWER SUSQ
VALLEY LATE TONIGHT/EARLY MONDAY.
VERY MILD TEMPS FOR EARLY DECEMBER WILL CONTINUE THROUGH TONIGHT.
THANKS TO THE GENERALLY LIGHT SOUTHERLY BREEZE...AND FAIR AMOUNT
OF CLOUD COVER...TEMPS WILL ONLY REACH THE UPPER 30S TO LOWER 40S
FOR MINS IN MOST PLACES /WHICH WILL BE 10-15F ABOVE NORMAL...WITH
THE GREATEST DEPARTURES OCCURRING ACROSS THE MOUNTAINS/. THE
TYPICALLY COLDER SPOTS NEAR AND TO THE EAST OF THE SUSQ VALLEY
/LIKE KTHV AND KSEG/ WILL DIP INTO THE LOWER AND MID 30S WITH NEAR
CALM AIR.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
CLOUDS LOWER AND THICKEN AS FRONTAL BOUNDARY APPROACHES.
PRECIPITATION WILL INCREASE IN THE AFTERNOON HOURS AND BECOME A
STEADY LIGHT RAIN OVERNIGHT. FRONT STILL WEST OF AREA SO MILD
TEMPERATURES CONTINUE THROUGH THE PERIOD.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
MODELS AGREE ON A COLD FRONT PUSHING ACROSS PA ON TUE...KEEPING
RAIN CHANCES HIGH...ESPECIALLY ACROSS THE SOUTHERN MTNS AND SUSQ
VALLEY. TEMPS TUE START OFF MILD...BUT WILL LIKELY REMAIN STEADY
OR FALL A BIT IN THE AFTERNOON...ESP IN THE NW. NO LARGE PUSH OF
COLD AIR BEHIND FRONT EVIDENT THOUGH.
LINGERING CHANCE FOR LIGHT RAIN/SNOW SHOWERS TUE NIGHT INTO WED AS
NARROW TROUGH AND COOLER AIR SLIDES OVERHEAD.
MUCH UNCERTAINTY IN LATE WEEK SOLUTIONS AS LARGE MODEL DIVERGENCE
CONTINUES. WAVE OF LOW PRESSURE SLIDES UP/EAST OF THE APPALACHIANS
THU...WITH ECMWF CONTINUING TO TRACK THIS TO OUR SE...THOUGH THE
GFS SOLUTION CONTINUES TO BECOME GRADUALLY MORE INTERESTING WITH A
MORE NORTHERLY TRACK. TOUGH TO RESOLVE THIS IN THE GRIDS OTHER
THAN TO EDGE POPS UPWARD A BIT ON THU AND SEE HOW THIS PLAYS OUT.
COULD BRING POTENTIAL FOR 0.50 INCH QPF...WITH SOME OF THAT
FALLING AS SNOW IF THE GFS SOLUTION WINS OUT...THOUGH AM STILL
LEANING MORE TOWARD THE ECMWF SOLUTION AT THIS TIME.
TROUGH DIGS IN FROM THE NW FRI NIGHT INTO SAT...BRINGING NOTICABLY
COLDER TEMPS AND WESTERLY FLOW. THIS WILL ALSO BRING A GOOD CHANCE
FOR LAKE EFFECT SNOW SHOWERS IN THE NW MTNS SAT. TEMPS SHOULD
BEGIN TO REBOUND EARLY NEXT WEEK.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
A LIGHT WIND AND MCLEAR SKIES ALLOWING RADIATION FOG TO FORM
ACROSS EASTERN PA LATE THIS EVENING. 04Z OBS SHOWING IFR CONDS IN
LOW CLOUDS/FOG OVERSPREADING SOUTHEAST PA. ADDITIONAL COOLING
OVERNIGHT SHOULD ALLOW THE FOG TO BECOME THICKER AND SPREAD
WESTWARD INTO THE SUSQ VALLEY. BULK OF LATEST SHORT RANGE MDL
DATA SUGGESTS IFR VSBYS ARE POSSIBLE LATE TONIGHT AT MDT/IPT AND
VERY LIKELY AT LNS.
FOG OVER THE SUSQ VALLEY SHOULD DISSIPATE BY MIDDAY MONDAY. FOCUS
WILL THEN SHIFT TOWARD APPROACHING COLD FRONT...WHICH WILL SPREAD
SHRA INTO THE NW MTNS DURING THE AFTN. IFR CIGS/VSBYS APPEAR
POSSIBLE AT BFD BY MON EVENING...AND DETERIORATING CONDS SHOULD
SPREAD ACROSS THE REST OF CENTRAL PA MON NITE WITH ARRIVAL OF
FRONT.
OUTLOOK...
TUE...AM LOW CIGS POSSIBLE.
WED...NO SIG WX EXPECTED.
THU...RAIN/SNOWLOW CIGS POSSIBLE.
FRI...SHSN POSSIBLE W MTNS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...ROSS/LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...ROSS/LAMBERT
LONG TERM...RXR
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
334 PM CST MON DEC 5 2011
.SHORT TERM...
THE MAIN FOCUS FOR THE SHORT TERM WILL CONTINUE TO BE THE WINTER
WEATHER IMPACTS ASSOCIATED WITH A STRONG UPPER-LOW PRESSURE SYSTEM
STILL PUSHING THROUGH THE FOUR CORNERS REGION. OVER THE COURSE OF
THE DAY...LIGHT SNOW SHOWERS HAVE PERSISTED ACROSS THE
CAPROCK...THOUGH VERY MINOR ACCUMULATIONS HAVE OCCURRED SINCE THE
MID-MORNING HOURS. HOWEVER...CURRENT OBS...SATELLITE AND RADAR
IMAGERY AND MODEL PROJECTIONS ARE SHOWING THE POTENTIAL FOR SOME
ADDITIONAL AREAS OF LIGHT SNOWFALL TO MOVE INTO THE AREA LATE THIS
AFTERNOON AND THIS EVENING AS ANOTHER LOBE OF ENERGY FROM THE
AFOREMENTIONED UPPER-LOW ROTATES OVER THE REGION. MOST OF THE QPF
SIGNALS SHOWN ARE FAIRLY LIGHT...BUT THE TTU WRF AND THE HRRR BOTH
SHOW SOME ENHANCED PRECIPITATION BANDS DEVELOPING ACROSS THE
NORTHWESTERN ZONES THIS EVENING. THIS THINKING SEEMS TO BE PLAUSIBLE
AS IR SATELLITE DATA IS INDICATING A BAND OF COLDER CLOUD TOPS
PUSHING INTO THE WESTERN PANHANDLE...WITH SURFACE OBS AT CLOVIS
DROPPING DOWN TO 1-2 SM DUE TO SNOW. THUS...SOME LOCALIZED BURSTS OF
MODERATE SNOW WILL BE POSSIBLE /PARTICULARLY ACROSS THE SW
PANHANDLE/ WHERE AN ADDITIONAL INCH OF SNOW MAY BE POSSIBLE TONIGHT.
HAVE INCREASED POPS TO LIKELY TO CHANCE ACROSS MUCH OF THE AREA THIS
EVENING...BEFORE LOWERING THEM AFTER MIDNIGHT AS PRECIPITATION
BEGINS TO WANE.
THE OTHER BIG CONCERN FOR THIS EVENING WILL BE THE BRISK NORTHERLY
WINDS AND STRONG COLD AIR ADVECTION OCCURRING...WHICH WILL DROP
TEMPERATURES INTO THE SINGLE DIGITS ACROSS THE SW PANHANDLE AND INTO
THE TEENS ACROSS THE REST OF THE AREA. GIVEN THE BITTERLY COLD
TEMPERATURES AND WINDS THAT SHOULD REMAIN ABOVE 10 MPH OVERNIGHT
SOME LOW WIND CHILLS WILL DEVELOP AFTER SUNSET. GIVEN THE POTENTIAL
FOR SOME DANGEROUSLY COLD WINDS CHILLS AT OR AROUND -5 DEGREES
OCCURRING LATER TONIGHT ACROSS THE NORTHWEST ZONES...HAVE PLACED
THAT AREA IN A WIND CHILL ADVISORY THROUGH 15Z TOMORROW. GIVEN THE
POTENTIAL FOR SOME ADDITIONAL /ALBEIT GENERALLY LIGHT/ SNOWFALL
ACCUMULATIONS ON THE CAPROCK THIS EVENING AND ALREADY HAZARDOUS
DRIVING CONDITIONS FROM BLACK ICE AND SNOW ON AREA ROADWAYS...HAVE
OPTED TO EXTEND THE WINTER WEATHER ADVISORY ON THE CAPROCK UNTIL
12Z. TOMORROW WILL BE A BITTERLY COLD DAY ACROSS THE AREA...AS HIGHS
WILL GENERALLY REMAIN WELL BELOW FREEZING IN THE 20S DUE TO VERY LOW
THICKNESS VALUES AND A CONTINUED NORTHERLY WIND.
&&
.LONG TERM...
AMPLIFIED PATTERN THROUGHOUT THE CONUS WILL SLOWLY RELAX BY MIDWEEK
RESULTING IN BRIEFLY ZONAL FLOW AND SLIGHTLY MILDER TEMPS ON THE
SOUTH PLAINS. THIS PATTERN HOWEVER STILL LOOKS TO BREAK DOWN ON
FRIDAY YIELDING BROADLY CYCLONIC FLOW COURTESY OF A DEEP POLAR
VORTEX TAKING RESIDENCE IN THE HUDSON BAY. JUST A GLANCING BLOW
FROM THIS BROAD TROUGH WILL YIELD A DRY POLAR FRONT LATE THU
NIGHT/EARLY FRI SERVING TO KNOCK HIGHS ON FRI 15-20 DEG BELOW CLIMO.
MEDIUM RANGE MODELS INSIST ON DEEPER WEST OR SWLY FLOW BY THE
WEEKEND INDICATIVE OF MORE SEASONABLE TEMPS.
GREATEST FORECAST CHALLENGE THIS PERIOD INVOLVES LO TEMPS TUE NIGHT
AS STRATUS CLEARS AND WINDS SLACKEN WITHIN AN ELONGATED SURFACE
RIDGE. CHOSE NOT TO LOWER INHERITED MIN TEMPS MUCH BELOW GUIDANCE
FOR NOW AS ALL NUMERICAL DATA INDICATE LIGHT WESTERLY FLOW
OVERNIGHT. SHOULD THESE LIGHT WINDS VEER MORE NLY IN LATER
FORECASTS...THEN THE RECORD DAILY LOW AT LBB /8 SET IN 2005/ MAY
BE IN JEOPARDY.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 8 21 7 40 17 / 60 10 0 0 0
TULIA 12 22 11 41 18 / 50 10 0 0 0
PLAINVIEW 13 23 10 40 18 / 50 10 0 0 0
LEVELLAND 13 22 9 40 19 / 50 10 0 0 0
LUBBOCK 15 25 11 40 19 / 40 10 0 0 0
DENVER CITY 14 26 16 40 20 / 50 10 0 0 0
BROWNFIELD 14 26 13 40 20 / 50 10 0 0 0
CHILDRESS 20 30 17 42 21 / 20 10 0 0 0
SPUR 20 30 15 44 20 / 30 10 0 0 0
ASPERMONT 21 33 20 45 22 / 20 10 10 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR THE FOLLOWING
ZONES: TXZ021>024-027>030-033>036-039>042.
WIND CHILL ADVISORY FROM 9 PM THIS EVENING TO 9 AM CST TUESDAY
FOR THE FOLLOWING ZONES: TXZ021>023-027-028.
&&
$$
22/93
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
537 PM CST TUE DEC 6 2011
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
.SYNOPSIS...SEASONABLY COLD AND VERY QUIET FOR THE EARLY PART OF
DECEMBER.
AMPLIFIED LNGWV PATTERN IN PLACE...WITH LARGE SCALE FLOW
DOMINATED BY MASSIVE RIDGE OVER THE ERN PAC. THE FLOW DOWNSTREAM
WAS SOMEWHAT SPLIT...WITH NRN STREAM MUCH STRONGER THAN THE
SRN...AND WITH TROFFING OVER ERN NOAM. THE TREND DURING THE FIRST
PART OF THE FCST PERIOD WL BE FOR BROAD ERN NOAM TROF TO EXPAND
SWD FM VORTEX IN THE HUDSON BAY RGN. THE SAME FEATURES SHOULD
REMAIN IN PLACE FOR THE LATTER HALF OF THE PERIOD...BUT WITH A
GRADUAL DECR IN AMPLITUDE.
TEMPS ACRS THE AREA HAVE COOLED TO NR NORMAL...AND WL CONT THE
DOWNSLIDE TO SOMEWHAT BLO NORMAL LEVELS AS THE UPR TROF DEEPENS
OVER THE RGN. ALTHOUGH THE N NOW HAS A DECENT SNOWCOVER...THE LACK
OF A WIDESPREAD DEEP SNOWCOVER ACRS THE ENTIRE REGION WL PREVENT
THIS FROM TURNING INTO A VERY COLD PERIOD. READINGS SHOULD REBOUND
DURING THE LATTER PART OF THE PERIOD AS UPR FLOW BECOMES MORE WLY.
GULF MOISTURE WL REMAIN TRAPPED WELL S OF THE AREA...AND DON/T SEE
ANY STG SYSTEMS IN THE FAST NWLY/WNWLY FLOW EITHER. EVEN THE
PROSPECT FOR LAKE-EFFECT LOOKS LOW AS FLOW WL BE RATHER WLY. SO
DON/T EXPECT MUCH PCPN DURING THE PERIOD.
&&
.SHORT TERM...TONIGHT AND WEDNESDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH
PRESSURE STRETCHING FROM THE CENTRAL GREAT PLAINS...ACROSS THE
GREAT LAKES...AND INTO QUEBEC THIS AFTERNOON. DESPITE THE SURFACE
HIGH...LOW CLOUDS OVER WESTERN AND CENTRAL WISCONSIN ARE
STUBBORNLY MOVING TO THE NORTHEAST. EARLIER FLURRY ACTIVITY OVER
THE DOOR PENINSULA IS ALSO FINALLY STARTING TO MOVE TO THE EAST AS
WELL. MEANWHILE...OVER THE LAKE WINNIPEG REGION...A DIVING
SHORTWAVE IS SENDING A WARM FRONT TO THE SOUTHEAST. AS THE SURFACE
HIGH DRIFTS TO THE SOUTH TONIGHT...CLOUDS AND TEMPS REMAIN THE
MAIN FORECAST CONCERNS.
TONIGHT...SURFACE HIGH PRESSURE WILL DRIFT TO THE SOUTH AS HEIGHT
FALLS OCCUR OVER SOUTH-CENTRAL CANADA AND THE FAR NORTHERN PLAINS.
LOW LEVEL SW WINDS WILL STRENGTHEN AND CONTINUE TO PUSH THE LOW
STRATUS TO THE NE. BASED ON THE LATEST SATELLITE OBS...TEND TO
THINK THE LOW STRATUS WILL STAY IN TACT OVER CENTRAL INTO EAST-
CENTRAL WISCONSIN THROUGH MID-EVENING WHILE NORTH- CENTRAL
WISCONSIN MAY ACTUALLY TURN PARTLY CLOUDY. UNLESS SOME HOLES
DEVELOP LATER THIS AFTERNOON...WILL TREND THE FORECAST THIS
DIRECTION. DRIER AIR IS THEN PROGGED TO PUSH THE STUBBORN STRATUS
TO THE EAST LATE THIS EVENING AND OVERNIGHT. SOME HIGH CLOUDS MAY
ARRIVE LATE AHEAD OF A SHEAR SHORTWAVE DIVING OVER SOUTH-CENTRAL
CANADA. THE STRENGTHENING WIND FIELD AND CLOUD COVER WILL KEEP
TEMPS WARMER THAN LAST NIGHT...AND WILL GO UPPER SINGLE DIGITS
NORTH TO LOWER 20S SE.
WEDNESDAY...THE SHEARED WAVE WILL SLIDE SOUTHEAST OVER LAKE
SUPERIOR...AND PUSH A WEAKENING COLD FRONT ACROSS THE FORECAST
AREA DURING THE MORNING. WILL SEE SOME SCT TO BKN MID CLOUDS WITH
THE FRONT...BUT NO REAL THREAT OF SNOW SHOWERS EXCEPT OVER
NORTHERN VILAS WHERE WNW WINDS MAY SEND A SCT SNOW SHOWERS ALONG
THE U.P.-WISCONSIN BORDER. TEMPS A COUPLE DEGREES WARMER THAN
TODAY OFF OF A WARMER START IN THE MORNING.
.LONG TERM...WED NGT THROUGH NEXT TUE. TRENDED TEMPS DOWN A
LITTLE BOTH THU AND FRI AS FCST AREA WL BE DOMINATED BY COLD AIR
FLOWING SEWD FM CANADA. WLY FLOW SHOULD KEEP SIG LAKE-EFFECT NE OF
THE AREA. THE CANADIAN GLOBAL MODEL BROUGHT SOME PCPN ACRS E-C WI
ON THU NGT INTO FRI AS BAROCLINIC LEAF TYPE FEATURES SLIDES ACRS
THE AREA. THE FEATURE WAS ALSO AT LEAST HINTED AT ON THE REST OF
THE MODELS...BUT THEY WERE ALL WEAKER AND FARTHER S. SO CANADIAN
SEEMS LIKE AN OUTLIER AND WL STICK WITH DRY FCST.
&&
.AVIATION...CLOUD FORECASTS WILL BE QUITE THE CHALLENGE THE NEXT
24 HOURS. LATE TUESDAY AFTERNOON...CLEAR SKIES WERE NOTED OVER MUCH
OF EAST CENTRAL AND FAR NORTHEAST WISCONSIN. MEANWHILE MVFR WITH
FLURRIES OVER MUCH OF THE WESTERN HALF OF WISCONSIN WERE SPREADING
STEADILY EASTWARD...PERHAPS REACHING GRB AT 02Z. WHILE THE
INCREASING CLOUD TREND EXPECTED EARLY THIS EVENING...QUESTION IF A
DECREASE LATE TONIGHT AS SOUTHWEST WINDS INCREASE. BACK EDGE OF
THE CLOUDS MAY REACH NORTH CENTRAL WISCONSIN LATER THIS EVENING
WHILE THE REST OF THE AREA MAY BE LATER TONIGHT. INCREASING
SOUTHWEST FLOW ALOFT WILL DEVELOP LLWS CONDITIONS LATE TONIGHT
INTO WEDNESDAY MORNING. LATER WEDNESDAY A COLD FRONT WILL SWEEP
OVER THE STATE. SINCE THE AIR MASS IS DRY ONLY A FEW FLURRIES
ANTICIPATED WHILE SOUTHWEST WINDS SHIFT NORTHWEST AT FROPA.
TDH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
245 PM CST MON DEC 5 2011
.SHORT TERM...
245 PM CST MON DEC 5 2011
BIGGEST FORECAST CONCERN IS ON CLOUDS AND TEMPERATURES...WITH LIGHT
PRECIPITATION CHANCES THIS EVENING ALSO A CONCERN.
18Z WATER VAPOR IMAGERY SHOWS SHORTWAVE TROUGH OVER
MINNESOTA...WHILE AT THE SURFACE A WEAK TROUGH WAS WORKING ITS WAY
THROUGH THE FORECAST AREA...BUT WAS WEAKENING WITH TIME. THIS
COMBINATION WAS PRODUCING WEAK LIFT THROUGH SATURATED LOWER LAYER
AND THUS SURFACE REPORTS INDICATING MAINLY LIGHT SNOW AND
FLURRIES...WITH SOME PATCHY FREEZING DRIZZLE.
05.12Z MODELS AGAIN IN GOOD AGREEMENT WITH THEIR MASS FIELDS. THERE
IS SOME DIFFERENCES IN SPEED OF COLDER PLUNGE OF AIR ON
THURSDAY...WITH THE NAM THE FASTEST. ONLY OTHER DIFFERENCE NOTED IS
GFS A LITTLE FASTER IN PUSHING THE STRATUS OUT ON TUESDAY.
FOR TONIGHT...SHORTWAVE IN MINNESOTA ROTATES INTO NORTHWEST
WISCONSIN. MODEL SOUNDINGS INDICATE WEAK LIFT CONTINUES IN THE
SATURATED LOWER LAYER DURING THE EVENING. 05.15Z RUC SOUNDINGS
QUESTIONABLE WITH REGARDS TO ICE IN THE CLOUD LAYER...WHILE NAM
SOUNDINGS SUGGEST MORE ICE. BASED ON REPORTS FROM THIS AFTERNOON
MENTION FLURRIES AND PATCHY FREEZING DRIZZLE FOR THE EVENING HOURS.
WITH THE CLOUDS DID GO ON THE WARMER SIDE OF THE GUIDANCE NUMBERS
FOR LOWS TONIGHT.
ON TUESDAY...GFS A LITTLE FASTER IN PUSHING THE STRATUS OUT OF THE
AREA...WHILE THE NAM KEEPS 850MB-925MB MOISTURE OVER THE AREA
THROUGHOUT THE DAY AND NOT CLEARING UNTIL EVENING. DID TAKE A
COMPROMISE...WITH A CLEARING TREND FROM WEST TO EAST DURING THE
AFTERNOON HOURS. TEMPERATURES WILL BE TRICKY WITH THE CLOUDS...BUT
WITH THE MORE PESSIMISTIC OUTLOOK DID GO WITH THE COOLER OF THE
GUIDANCE NUMBERS.
DO EXPECT CLEAR SKIES...AT LEAST FOR A SHORT PERIOD OF TIME TUESDAY
NIGHT. HOWEVER...ANOTHER SHORTWAVE BEGINS TO DROP SOUTHWARD OUT OF
SOUTHERN CANADA LATE TUESDAY NIGHT...AND MODELS HINT AT AN INCREASE
IN HIGH LEVEL CLOUDS. THESE CLOUDS THEN DROP ACROSS THE AREA ON
WEDNESDAY AND WEDNESDAY NIGHT AHEAD OF THE ASSOCIATED COLD FRONT.
TEMPERATURES LOOK TO BE A LITTLE MILDER AHEAD OF THE FRONT...BUT
STILL BELOW NORMAL WITH HIGHS FROM THE MIDDLE 20S IN THE SNOW
COVERED LOCATIONS...TO THE LOWER 30S IN THE NON SNOW COVERED AREAS.
ON THURSDAY COLD AIR BEGINS TO SURGE INTO THE AREA BEHIND THE FRONT.
AS MENTIONED BEFORE NAM QUICKER IN MOVING THIS COLD AIR INTO THE
REGION AND AGAIN USED A MODEL CONSENSUS FOR HIGHS. 05.12 GFS AND
ECMWF ALSO GENERATING SOME LIGHT PRECIPITATION ALONG THE LEADING EDGE
OF THE COLD AIR ACROSS IOWA IN BAND OF WEAK FRONTOGENESIS. WITH THE
BULK OF PUSH OF COLD AIR THURSDAY NIGHT...DID ADD SOME LOWER END
SNOW PROBABILITIES ACROSS NORTHEAST IOWA AND SOUTHWEST WISCONSIN.
.LONG TERM...
245 PM CST MON DEC 5 2011
A DRY NORTHWEST LOW PATTERN WILL CONTINUE FOR FRIDAY AND SATURDAY
AND THIS WILL LEAD TO BELOW NORMAL TEMPERATURES. THE FLOW WILL BECOME
MORE ZONAL ON SUNDAY AS A TROUGH BUILDS INTO THE WESTERN CONUS. AS
THE TROUGH PROGRESSES INTO THE CENTRAL SECTIONS OF THE COUNTRY...THE
FLOW WILL BECOME MORE SOUTHWESTERLY. DRY CONDITIONS WILL CONTINUE
THROUGH MONDAY...BUT WITH A MORE SOUTHERLY WIND...TEMPERATURES WILL
WARM SATURDAY AND SUNDAY...WITH HIGHS EXPECTED IN THE 30S BOTH SUNDAY
AND MONDAY.
&&
.AVIATION...TODAY THROUGH TUESDAY
1135 AM CST MON DEC 5 2011
SHORT WAVE TROUGH MOVING INTO MINNESOTA SHOULD KEEP CLOUDS IN MOST
AREAS BUT BEEN BATTLING SOME BREAKS THIS MORNING. EXPECT THAT TO BE
SHORT LIVED...NEXT FEW HOURS...AND THEN AT LEAST MVFR CEILINGS
MOVING BACK IN.
ENOUGH GENERAL LIFT FOR PRECIPITATION AS WELL...ALBEIT MAINLY NORTH
OF INTERSTATE 90. MODEL SOUNDINGS SUGGEST TOP OF CLOUD LAYER MAY BE
JUST COLD ENOUGH TO INTRODUCE ICE INTO COLUMN BUT VERY MARGINAL.
WILL BANK ON BULK OF PRECIPITATION REMAINING SNOW BUT COULD NOT RULE
OUT BRIEF PATCHY FREEZING DRIZZLE. VISIBILITIES WITH SNOW FALLING
HAVE REMAINED MAINLY MVFR AND NO BIG CHANGE EXPECTED BEFORE
PRECIPITATION ENDS THIS EVENING.
MODELS HAVE ALSO BEEN SLOWING IDEA OF DRIER LOW LEVEL AIR COMING IN
BEHIND THIS SHORT WAVE TROUGH SO CLOUDS EXPECTED TO REMAIN TOUGH
WELL INTO TUESDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
245 PM CST MON DEC 5 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RABERDING
LONG TERM...RABERDING
AVIATION.....SHEA/ZT
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
203 PM CST MON DEC 5 2011
.SHORT TERM...TONIGHT AND TUESDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW THE STATE OF
WISCONSIN LOCATED BETWEEN A COLD FRONT RUNNING UP THE EASTERN SIDE
OF THE APPALACHIANS...AND A POLAR SURFACE HIGH STRETCHING ACROSS THE
DAKOTAS EARLY THIS AFTERNOON. A WEAK SURFACE TROUGH REMAINS A
NUISANCE WHICH HANGS BACK FROM JUST SOUTH OF MILWAUKEE TO EAU
CLAIRE. RADAR RETURNS HAVE GRADUALLY ERODED OVER CENTRAL AND
EAST-CENTRAL WISCONSIN OVER THE COURSE OF THE DAY...THOUGH BEEFIER
RETURNS AND SURFACE OBS SHOW LIGHT SNOW SHOWERS OCCURRING OVER
WESTERN WISCONSIN. SOME HOLES IN THE CLOUDS ARE TRYING TO DEVELOP
OVER NORTHEAST WISCONSIN...AND PERHAPS INTO CENTRAL WISCONSIN AS
WELL. AS THE SURFACE HIGH SHIFTS EAST TONIGHT...CLOUD TRENDS AND
TEMPS ARE THE MAIN FORECAST CONCERNS.
TONIGHT...HIGH PRESSURE OVER THE NORTHERN PLAINS WILL BUILD EAST
OVER THE NORTHERN MISSISSIPPI VALLEY. HOWEVER...FLOW WILL CONTINUE
TO BE OUT OF THE NORTH AND LIGHTLY ADVECTING CLOUDS OFF LAKE
SUPERIOR. IN ADDITION...12Z GUIDANCE SUPPORTS LINGERING LOW LEVEL
CONVERGENCE OVER CENTRAL WISCONSIN THAT WILL KEEP AN AREA OF
ENHANCED RH IN PLACE. KEPT A FLURRY MENTION OVER THE FAR WESTERN
CWA TO ACCOUNT FOR THIS. WITH PLENTY OF CLOUDS UPSTREAM...HAVE A
HARD TIME GOING BELOW MOSTLY CLOUDY CONDITIONS. THERE WILL BE
UNDOUBTEDLY SUCKER HOLES THAT WILL DEVELOP WITHIN THE
STRATUS...MOSTLY LIKELY WITHIN THE DOWNSLOPING AREAS OF NORTHEAST
WISCONSIN. WILL PLAY THE PROBABILITY THAT SCT CONDITIONS DEVELOP
THERE...BUT LEAVE MOSTLY CLOUDY CONDITIONS ELSEWHERE...WITH SCT SNOW
SHOWERS OVER THE SNOW BELT OF N-C WISCONSIN. LOWS IN THE LOWER
TEENS NORTH TO MIDDLE 20S SOUTHEAST. TEMPS COULD BE MUCH COLDER
OVER THE SNOW PACK OF N-C WISCONSIN IF HOLES IN THE CLOUDS DO
DEVELOP THERE.
TUESDAY...HIGH PRESSURE BUILDS INTO THE REGION TOMORROW. ANY
SURFACE CONVERGENCE ALONG THE LINGERING TROUGH OVER CENTRAL
WISCONSIN IS PROGGED TO DISSIPATE IN THE MORNING...BUT MODELS
INDICATE THE REMNANTS OF THE ENHANCED RH MOVING EAST AS LIGHT SW
FLOW DEVELOPS. ALSO SEE SIGNS OF STEEP LOW LEVEL LAPSE RATES WITH
HEATING OF THE DAY THAT POINTS TOWARDS STRATO-CU DEVELOPING. WITH
CLOUDS UNDER THE HIGH CURRENTLY...WILL SIDE MORE PESSIMISTICALLY
WITH CLOUD COVER...WHICH WILL KEEP MOSTLY CLOUDY CONDITIONS OVER
NORTH-CENTRAL WISCONSIN FOR THE MORNING...AND PARTLY CLOUDY
CONDITIONS EVERYWHERE FOR THE AFTERNOON. HIGHS RANGING FROM THE
LOWER 20S NORTH TO AROUND 30 DEGREES SOUTHEAST.
.LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY...THE MAIN FCST
CONCERN IS THE ARRIVAL OF ARCTIC AIR LATER IN THE WEEK.
SHORT-WAVE ENERGY CURRENTLY OVER THE GULF OF ALASKA WILL TOP THE
WEST COAST RIDGE...THEN HELP TO CARVE A BROAD TROF OVER THE
CENTRAL U.S. BY THURSDAY. A SURGE OF ARCTIC AIR IS EXPECTED TO
ARRIVE IN WI ON THURSDAY...WITH H8 TEMPS PLUMMETING TO -16 TO
-20 C BY FRIDAY. THIS WILL LEAD TO OUR COLDEST TEMPERATURES SO
FAR THIS SEASON. THE COLDER WEATHER WILL NOT LAST LONG...AS
SOUTHWEST WINDS DEVELOP IN THE WAKE OF THE RETREATING ARCTIC
HIGH OVER THE WEEKEND. H8 TEMPS ARE EXPECTED TO SURGE TO 0 TO
+4 C BY SATURDAY NIGHT/SUNDAY.
A WEAK COLD FRONT IS EXPECTED TO MOVE THROUGH THE REGION ON
WEDNESDAY...WITH A STRONGER ARCTIC FRONT ARRIVING ON THURSDAY.
HAVE BEEN WATCHING FOR POSSIBLE SNOW DEVELOPMENT AS THE RRQ OF A
STG UPPER JET INTERACTS WITH THE ARCTIC FRONT THURSDAY NIGHT
INTO FRIDAY...BUT THE CONCENSUS OF THE MODELS...INCLUDING THE
12Z/MON ECMWF...IS THAT SNOW WILL DEVELOP TO OUR SOUTH AND EAST.
WILL NOT CARRY ANY POPS AT THIS TIME...BUT SUBSEQUENT SHIFTS WILL
STILL NEED TO KEEP AN EYE ON THIS.
DESPITE THE PRESENCE OF A COLD AIR MASS FROM WEDNESDAY THROUGH
FRIDAY NIGHT...WIND TRAJECTORIES WILL BE TOO WESTERLY FOR ANY
APPRECIABLE LK-EFFECT SNOW.
MODELS HAVE BACKED OFF SLIGHTLY ON THE MAGNITUDE OF THE COLD SNAP
LATE IN THE WORK WEEK...WITH H8 TEMPS TRENDING A FEW DEGREES
WARMER. EVEN SO...STILL EXPECT MAX TEMPS TO BE ABOUT 10 DEGREES
BLO NORMAL ON FRIDAY. THE COLDER WEATHER WILL BE SHORT-LIVED...
WITH ABOVE NORMAL TEMPERATURES QUICKLY RETURNING BY SUNDAY.
A WEAK COLD FRONT MAY IMPACT THE REGION ON MONDAY...BUT SHOULD
NOT HAVE ANY SIGNIFICANT IMPACT ON OUR WEATHER.
&&
.AVIATION...CLOUDY OR MOSTLY CLOUDY VFR CONDITIONS WILL PREVAIL
ACROSS THE TAF SITES THROUGH THE PERIOD. SOME HOLES IN THE STRATUS
WILL LIKELY DEVELOP...BUT TRYING TO PREDICT WHERE IS DIFFICULT. THE
MOST LIKELY AREAS WILL BE OVER THE FOX VALLEY WHERE A SMALL
DOWNSLOPING COMPONENT WILL EXIST. SOME POSSIBILITY OF LOWERING CIGS
OVER NORTH-CENTRAL WISCONSIN LATE TONIGHT INTO TOMORROW MORNING
WHERE MODELS PROJECT STEEP LOW LEVEL LAPSE RATES DEVELOPING. WILL
REMAIN OPTIMISTIC GIVEN SOME LOW END VFR CIGS UPSTREAM.
MPC
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/TSK
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1252 PM CST MON DEC 5 2011
.UPDATE...
CONVERGING WINDS ALONG THE LONG AXIS OF LAKE MICHIGAN HELPED TO
CREATE A LAKE EFFECT PRECIP BAND. NORTH-NORTHEAST FLOW PUSHED THE
BAND ONSHORE FROM PORT WASHINGTON SOUTH TO KENOSHA AND WAUKEGAN.
LAKE EFFECT PUSHED WELL INLAND...NOW AFFECTING PARTS OF EASTERN DANE
COUNTY. THE PRECIP IS FALLING IN THE FORM OF RAIN RIGHT ALONG THE
SHORELINE AND AS SNOW INLAND. SOME OF THE HEAVIER RETURNS ON RADAR
OVER MKE HAVE BEEN REPORTED AS SNOW BY THE OBSERVER AT THE AIRPORT.
THE LAKE EFFECT BAND APPEARS TO BE SLOWLY SHIFTING SOUTHWARD THIS
AFTERNOON. THE SNOW/DRIZZLE COULD VERY WELL END AT MITCHELL AIRPORT
BY 2 PM AND NOT RETURN FOR THE REST OF THE DAY DUE TO DRIER AIR IN
NORTHEAST WI WORKING ITS WAY SOUTHWARD. WILL NEED TO MONITOR RADAR
TRENDS.
THERE WAS A PERIOD OF SNOW AT THE NWS OFFICE NEAR DOUSMAN/SULLIVAN
THAT HAD DENDRITE SNOW CRYSTALS...BUT THE MAJORITY OF THE SNOWFLAKES
HAVE BEEN VERY SMALL. RUC SNDGS SHOWING SATURATED LAYER UP TO 4 TO
5KFT...WITH A FAIRLY DEEP LAYER IN THE -8 TO -10C TEMP
AREA...LEADING TO SMALL ICE CRYSTALS RATHER THAN LARGER DENDRITES.
MEANWHILE...AN AREA OF LIGHT SNOW ASSOCIATED WITH PERSISTENT
VORTICITY ADVECTION SET UP ACROSS NORTHERN WI YESTERDAY AND IS
SLOWLY SHIFTING SOUTHWARD TODAY. MODELS SHOW THE AREA OF SNOW
ORIENTING ITSELF MORE NORTHWEST/SOUTHEAST BY LATE THIS AFTERNOON. WE
CAN EXPECT THE SLIGHT SNOW OVER WEST CENTRAL WI TO SHIFT INTO SOUTH
CENTRAL WI LATER THIS AFTERNOON. IT IS QUESTIONABLE IF THE FAR
SOUTHWEST FORECAST AREA WILL SEE THIS SNOW.
&&
.AVIATION/18Z TAFS/...
LOW-LEVEL MOISTURE WILL BE TRAPPED UNDER AN INVERSION ACROSS
SOUTHERN WISCONSIN THROUGH THE DAY TODAY...SO STRATUS WILL HOLD
IN THROUGH THE FORECAST PERIOD. MVFR CIGS ARE EXPECTED TO IMPROVE TO
VFR LATE THIS AFTERNOON AS DRIER AIR OVER NORTHEAST WI WORKS INTO
THE AREA.
LAKE EFFECT PRECIP PUSHING ONSHORE SOUTH OF PORT WASHINGTON EARLY
THIS AFTERNOON. THE PRECIP IS FALLING IN THE FORM OF RAIN RIGHT
ALONG THE SHORELINE AND AS SNOW INLAND. SOME OF THE HEAVIER RETURNS
ON RADAR OVER MKE HAVE BEEN REPORTED AS SNOW AND DRIZZLE BY THE
OBSERVER AT THE AIRPORT.
THE LAKE EFFECT BAND APPEARS TO BE SLOWLY SHIFTING SOUTHWARD THIS
AFTERNOON. THE SNOW/DRIZZLE COULD VERY WELL END AT MITCHELL AIRPORT
BY 2 PM AND NOT RETURN FOR THE REST OF THE DAY DUE TO DRIER AIR IN
NORTHEAST WI WORKING ITS WAY SOUTHWARD. PRECIP SHOULD PERSIST AT ENW
A WHILE LONGER. WILL NEED TO MONITOR RADAR TRENDS.
THERE COULD BE ANOTHER ROUND OF LAKE EFFECT SHOWERS TO CONTEND WITH
TUE MORNING FROM MKE SOUTHWARD. PLENTY OF UNCERTAINTY AT THIS TIME.
&&
.MARINE...
PERSISTENT 10 TO 20 KNOT NORTH WINDS BUILDING 3 TO 5 FOOT WAVES.
THOUGH WINDS BEGIN TO EASE BY TUESDAY MORNING AND THEN BACK
NORTHWEST TUESDAY AFTERNOON...WAVES WILL BE SLOWER
TO SUBSIDE...SO SMALL CRAFT ADVISORY IN EFFECT THROUGH 6 PM
TUESDAY. LAKE-EFFECT SNOW/RAIN SHOWERS WILL ALSO
REDUCE VISIBILITIES AT TIMES THROUGH TUESDAY AFTERNOON.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 6 PM CST TUESDAY FOR LMZ643>646.
&&
$$
UPDATE...MRC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
547 AM CST MON DEC 5 2011
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
314 AM CST MON DEC 5 2011
MAIN FORECAST CONCERNS ARE ON SNOW SHOWERS/FREEZING DRIZZLE TODAY
AND WHEN CLOUDS CLEAR.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS
SHOWED UPPER RIDGING OVER THE EAST PACIFIC INTO SOUTHWEST CANADA...
TROUGHING FROM JAMES BAY SOUTHWEST INTO THE FOUR CORNERS REGION...
AND RIDGING ALONG THE EAST COAST OF THE U.S.. WITHIN THE UPPER
TROUGHING...THE MAIN FEATURE OF INTEREST IS A SHORTWAVE OVER EASTERN
SOUTH DAKOTA. WITH THIS SHORTWAVE...AREAS OF LIGHT SNOW WERE BEING
OBSERVED...WHICH WERE ALSO ALONG A WEAK NORTHWEST-SOUTHEAST ORIENTED
TROUGH THROUGH THE SIOUX FALLS AREA. FARTHER EAST...ANOTHER WEAK
SURFACE TROUGH WAS ANALYZED FROM NEAR EAU CLAIRE TO SHEBOYGAN WI.
CONVERGENCE ALONG THIS TROUGH COMBINED WITH LOW LEVEL MOISTURE IN
PLACE NOTED BY THE STRATUS DECK IS PRODUCING SCATTERED SNOW SHOWERS
AROUND THE TROUGH. THERE HAVE EVEN BEEN SOME FREEZING DRIZZLE
REPORTS...MOSTLY LAST EVENING THROUGH FAIRLY RECENTLY AT VOLK
FIELD...BECAUSE OF LACK OF ICE ISSUES. THE LACK OF ICE IS NOTED BY
THE 00Z GRB AND MPX SOUNDINGS WHICH WERE ONLY SATURATED TO -11 TO
-13C RESPECTIVELY. THE AFOREMENTIONED STRATUS IS QUITE
WIDESPREAD...ENCOMPASSING ALL OF WI...MUCH OF IOWA...THE EASTERN
DAKOTAS AND ALMOST ALL OF MINNESOTA. AS A RESULT OF THE CLOUD
COVER...TEMPERATURES HAVE STAYED MOSTLY IN THE 20S ALL NIGHT.
TODAY AND TONIGHT...SHORTWAVE OVER EASTERN SOUTH DAKOTA IS PROGGED
TO LIFT NORTHEAST ALONG THE EAST SIDE OF THE UPPER TROUGH...CROSSING
NORTHWEST WI AND THE U.P. THIS EVENING. THE TRACK OF THIS
SHORTWAVE...COMBINED WITH MODEL FORECASTS OF THE ASSOCIATED
SURFACE TROUGH BASICALLY DISSIPATING...SUGGESTS LIGHT SNOW WITH IT
SHOULD STAY AWAY FROM THE FORECAST AREA. MEANWHILE...THE SURFACE
TROUGH CURRENTLY PRODUCING THE LIGHT SNOW OVER CENTRAL WISCONSIN
IS FORECAST BY THE 05.00Z NAM/REGIONAL CANADIAN AND 05.06Z HRRR TO
DROP SOUTHWEST THROUGH THE DAY TODAY...POSSIBLY REACHING KLSE BY
00Z. BY THE TIME IT REACHES KLSE...ALL OF THESE MODELS HAVE IT
WEAKENING. THIS SEEMS REASONABLE DUE TO THE LARGE 1040MB SURFACE
HIGH OVER THE WESTERN DAKOTAS PROGGED TO MOVE INTO WESTERN
MINNESOTA...AND THAT IS IN RESPONSE TO THE UPPER TROUGH
APPROACHING THE AREA. THEREFORE...HAVE ONLY INCLUDED A BAND OF
20-30 PERCENT CHANCES ALONG THE SURFACE TROUGH TODAY. THIS
REFLECTS CURRENT RADAR TRENDS WELL TOO. AS FAR AS PRECIPITATION
TYPE GOES...MODEL SOUNDINGS INDICATE THE SAME SETUP AS NOW WITH
CLOUD TOP TEMPS AT MOST AROUND -11C. SINCE THE MAJORITY OF REPORTS
THUS FAR OVERNIGHT HAVE BEEN -SN...WILL CONTINUE THAT BUT MENTION
A CHANCE FOR FREEZING DRIZZLE SINCE -11C REPRESENTS ABOUT A 60
PERCENT CHANCE THAT ICE ACTUALLY EXISTS IN THE CLOUD PER AIRCRAFT
RESEARCH. CONFIDENCE CERTAINLY IS NOT HIGH ENOUGH TO ISSUE A
FREEZING RAIN ADVISORY...ESPECIALLY GIVEN THE MAJORITY OF SNOW
REPORTS. OTHERWISE...ONLY OTHER CONCERN IS THE STRATUS. NAM/RUC
HAVE BEEN DOING THE BEST THUS FAR IN THE LOW LEVEL RH PROGS
MATCHING UP WITH THE STRATUS. BOTH SUGGEST THE AREA STAYS CLOUDY
TODAY...WHICH MAKES SENSE WITH 925-950MB WINDS NORTHEAST TO NORTH.
TONIGHT...THERE COULD BE SOME BREAK UP...ESPECIALLY ALONG THE
NORTHWEST EDGE OF THE FORECAST AREA LATE TONIGHT AS 925MB WINDS
BACK TO THE NORTHWEST AT 12Z. GIVEN THE COLD NATURE OF THE AIRMASS
IN PLACE...ANY CLEARING COULD CAUSE TEMPERATURES TO TANK INTO THE
SINGLE DIGITS. MEANWHILE...CLOUDY AREAS WOULD STAY WARMER IN THE
TEENS AND 20S. NEEDLESS TO SAY...TRICKY LOW TEMPERATURE FORECAST
FOR TONIGHT. GENERALLY FOLLOWED A BLEND OF GUIDANCE FOR HIGHS
TODAY.
TUESDAY THROUGH WEDNESDAY NIGHT...UPPER LEVEL PATTERN IS FORECAST TO
UNDERGO SOME CHANGE DURING THIS PERIOD...IN RESPONSE TO A POWERFUL
UPPER LEVEL TROUGH DIGGING DOWN THROUGH CENTRAL CANADA. AS THIS
TROUGH DIGS SOUTHWARD IT WILL HELP TO PUSH THE TROUGH APPROACHING
THE AREA TONIGHT THROUGH ON TUESDAY...GIVE A BRIEF PERIOD OF UPPER
RIDGING ON TUESDAY NIGHT...THEN CAUSE THE UPPER FLOW TO TURN ZONAL
FOR THE REST OF THE PERIOD. AS THE UPPER TROUGH MOVES THROUGH THE
AREA ON TUESDAY...WHICH MEANS THE SURFACE RIDGE WILL DO THE SAME...
ANTICIPATING SKIES TO CLEAR NORTHWEST TO SOUTHEAST. ALTHOUGH MORE
SUN IS EXPECTED...THE 850MB TEMPS FALL TO -10 TO -12C...SO HIGHS
WILL ACTUALLY END UP COOLER THAN TODAY. MOSTLY CLEAR AND COOL
CONDITIONS CONTINUE TUESDAY NIGHT THANKS TO SUBSIDENCE UNDER THE
UPPER RIDGING. A 5-10 KT SOUTHWEST WIND WILL HELP KEEP TEMPERATURES
FROM TANKING BELOW ZERO TUESDAY NIGHT...THOUGH THE WIND IS EXPECTED
TO DROP WIND CHILLS INTO THE SINGLE DIGITS BELOW ZERO. A BRIEF WARM
UP IS FORECAST FOR WEDNESDAY WITH 850MB TEMPS CLIMBING UP TO AROUND
-6C AT 18Z. HOWEVER...A COLD FRONT COMING THROUGH THE ZONAL FLOW
LOOKS TO CROSS LATE IN THE DAY...BRINGING AN INCREASE OF MID-HIGH
CLOUDS BEHIND IT. AS WE GO THROUGH WEDNESDAY NIGHT...THE 05.00Z
GFS/CANADIAN/NAM ALL WANT TO PRODUCE SOME LIGHT PRECIPITATION OUT OF
THESE CLOUDS...LIKELY A RESULT OF SOME MID-LEVEL FRONTOGENESIS. NOT
QUITE SOLD ON THIS PRECIPITATION YET...ESPECIALLY WITH THE 05.00Z
ECMWF STILL DRY AND REALLY THE FIRST SIGNAL OF IT. THEREFORE...HAVE
ONLY INCREASED CLOUD COVER AT THIS TIME. THE CLOUDS SHOULD HELP KEEP
TEMPERATURES UP SOME WEDNESDAY NIGHT. FOLLOWED A BLEND OF GUIDANCE
THEN.
.LONG TERM...THURSDAY THROUGH SUNDAY NIGHT
314 AM CST MON DEC 5 2011
05.00Z ECMWF/GFS/CANADIAN AND GFS ENSEMBLES REMAIN IN PRETTY GOOD
AGREEMENT FOR THE LONG TERM FORECAST...BOTH BETWEEN EACH RUN AND
WHAT WAS SEEN YESTERDAY...LEADING TO ABOVE AVERAGE CONFIDENCE. A
SHORTWAVE TROUGH COMING AROUND THE POWERFUL CENTRAL CANADA TROUGH IS
PROGGED TO DROP INTO THE NORTHERN PLAINS THURSDAY...CROSSING THE
AREA THURSDAY NIGHT INTO FRIDAY. THERE REMAINS SOME SIGNALS OF A
MID-LEVEL FRONTOGENESIS BAND AND UPPER JET INDUCED PRECIPITATION AS
THIS SHORTWAVE TROUGH APPROACHES THE AREA. HOWEVER...A CONSENSUS OF
THE MODELS HAS SHOWN A SHIFT SOUTH...SUCH THAT IT CROSSES MOSTLY THE
SOUTHERN HALF OF IOWA AND NORTHERN ILLINOIS DURING THURSDAY NIGHT.
NOTE...THE NEW 05.00Z ECMWF HAS SHIFTED BACK NORTH...BUT NOT ENOUGH
CONFIDENCE EXISTS TO PUT CHANCES FARTHER NORTH YET. AFTER THIS...IT
LOOKS LIKE A SOLID DRY FORECAST HEADING INTO THE WEEKEND AS THE
UPPER FLOW TRANSITIONS TO ZONAL. SHOULD SEE A WARMING TREND TOO AS
DOWNSLOPING MOTION OFF THE ROCKIES OF PACIFIC AIR CAUSES
TEMPERATURES TO MODIFY. SO AFTER A CHILLY FRIDAY AND FRIDAY NIGHT
WITH 850MB TEMPS PROGGED AS COLD AS -20C...THESE WILL WARM UP
DRAMATICALLY...REACHING TO 0 TO +2C BY SUNDAY. LOOKING
BEYOND...RIGHT NOW IT APPEARS ABOVE NORMAL TEMPERATURES COULD
PERSIST INTO THE EARLY PORTION OF NEXT WEEK WITH ZONAL FLOW
CONTINUING.
&&
.AVIATION...TODAY THROUGH TUESDAY
547 AM CST MON DEC 5 2011
CONSIDERABLE MOISTURE IN THE 925-850MB LAYERS REMAINS ACROSS MN/IA/
WI...TRAPPED UNDER AN INVERSION NEAR 800MB. WITH WEAK GRADIENTS/
LIGHT WINDS IN THE SFC-800MB LAYER...THIS MOISTURE AND RESULTING
MVFR/ LCL VFR STRATUS CLOUDS WILL BE RATHER PERSISTENT ACROSS THE
AREA TODAY INTO TONIGHT. A WEAK SHORTWAVE DROPPING ACROSS THE
WESTERN GREAT LAKES REGION TODAY WILL PROVIDE SOME WEAK CONVERGENCE/
LIFT FOR PATCHY -SN/-FZDZ OR -SHSN. WITH LIMITED COVERAGE EXPECTED
FOR ANY PRECIP AND VSBYS REMAINING 6SM OR GREATER DID NOT INCLUDE
-SN OR -FZDZ IN THE TAFS AT THIS TIME. DRIER HIGH PRESSURE BEGINS TO
BUILD INTO TONIGHT...WITH DECREASING/CLEARING CLOUDS THRU THE NIGHT
WEST/NORTH OF A KOMA-KMSP-KDLH LINE. QUESTION IS HOW QUICKLY WILL
THIS LOW CLOUD CLEARING PROGRESS EAST TOWARD/ACROSS THE TAF SITES
LATER TONIGHT/TUE. GIVEN THE GENERAL TENACITY OF LOW CLOUD DECKS AT
THIS TIME OF YEAR...KEPT BKN MVFR CIGS AT BOTH KRST/KLSE THRU 12Z
TUE. HOWEVER DID GRADUALLY RAISE CIGS THIS AFTERNOON/TONIGHT AS
THE DRIER AIR ON THE LEADING EDGE OF THE HIGH SLOWLY FILTERS INTO
THE AREA.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
314 AM CST MON DEC 5 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM....AJ
AVIATION.....RRS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
314 AM CST MON DEC 5 2011
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
314 AM CST MON DEC 5 2011
MAIN FORECAST CONCERNS ARE ON SNOW SHOWERS/FREEZING DRIZZLE TODAY
AND WHEN CLOUDS CLEAR.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS
SHOWED UPPER RIDGING OVER THE EAST PACIFIC INTO SOUTHWEST CANADA...
TROUGHING FROM JAMES BAY SOUTHWEST INTO THE FOUR CORNERS REGION...
AND RIDGING ALONG THE EAST COAST OF THE U.S.. WITHIN THE UPPER
TROUGHING...THE MAIN FEATURE OF INTEREST IS A SHORTWAVE OVER EASTERN
SOUTH DAKOTA. WITH THIS SHORTWAVE...AREAS OF LIGHT SNOW WERE BEING
OBSERVED...WHICH WERE ALSO ALONG A WEAK NORTHWEST-SOUTHEAST ORIENTED
TROUGH THROUGH THE SIOUX FALLS AREA. FARTHER EAST...ANOTHER WEAK
SURFACE TROUGH WAS ANALYZED FROM NEAR EAU CLAIRE TO SHEBOYGAN WI.
CONVERGENCE ALONG THIS TROUGH COMBINED WITH LOW LEVEL MOISTURE IN
PLACE NOTED BY THE STRATUS DECK IS PRODUCING SCATTERED SNOW SHOWERS
AROUND THE TROUGH. THERE HAVE EVEN BEEN SOME FREEZING DRIZZLE
REPORTS...MOSTLY LAST EVENING THROUGH FAIRLY RECENTLY AT VOLK
FIELD...BECAUSE OF LACK OF ICE ISSUES. THE LACK OF ICE IS NOTED BY
THE 00Z GRB AND MPX SOUNDINGS WHICH WERE ONLY SATURATED TO -11 TO
-13C RESPECTIVELY. THE AFOREMENTIONED STRATUS IS QUITE
WIDESPREAD...ENCOMPASSING ALL OF WI...MUCH OF IOWA...THE EASTERN
DAKOTAS AND ALMOST ALL OF MINNESOTA. AS A RESULT OF THE CLOUD
COVER...TEMPERATURES HAVE STAYED MOSTLY IN THE 20S ALL NIGHT.
TODAY AND TONIGHT...SHORTWAVE OVER EASTERN SOUTH DAKOTA IS PROGGED
TO LIFT NORTHEAST ALONG THE EAST SIDE OF THE UPPER TROUGH...CROSSING
NORTHWEST WI AND THE U.P. THIS EVENING. THE TRACK OF THIS
SHORTWAVE...COMBINED WITH MODEL FORECASTS OF THE ASSOCIATED
SURFACE TROUGH BASICALLY DISSIPATING...SUGGESTS LIGHT SNOW WITH IT
SHOULD STAY AWAY FROM THE FORECAST AREA. MEANWHILE...THE SURFACE
TROUGH CURRENTLY PRODUCING THE LIGHT SNOW OVER CENTRAL WISCONSIN
IS FORECAST BY THE 05.00Z NAM/REGIONAL CANADIAN AND 05.06Z HRRR TO
DROP SOUTHWEST THROUGH THE DAY TODAY...POSSIBLY REACHING KLSE BY
00Z. BY THE TIME IT REACHES KLSE...ALL OF THESE MODELS HAVE IT
WEAKENING. THIS SEEMS REASONABLE DUE TO THE LARGE 1040MB SURFACE
HIGH OVER THE WESTERN DAKOTAS PROGGED TO MOVE INTO WESTERN
MINNESOTA...AND THAT IS IN RESPONSE TO THE UPPER TROUGH
APPROACHING THE AREA. THEREFORE...HAVE ONLY INCLUDED A BAND OF
20-30 PERCENT CHANCES ALONG THE SURFACE TROUGH TODAY. THIS
REFLECTS CURRENT RADAR TRENDS WELL TOO. AS FAR AS PRECIPITATION
TYPE GOES...MODEL SOUNDINGS INDICATE THE SAME SETUP AS NOW WITH
CLOUD TOP TEMPS AT MOST AROUND -11C. SINCE THE MAJORITY OF REPORTS
THUS FAR OVERNIGHT HAVE BEEN -SN...WILL CONTINUE THAT BUT MENTION
A CHANCE FOR FREEZING DRIZZLE SINCE -11C REPRESENTS ABOUT A 60
PERCENT CHANCE THAT ICE ACTUALLY EXISTS IN THE CLOUD PER AIRCRAFT
RESEARCH. CONFIDENCE CERTAINLY IS NOT HIGH ENOUGH TO ISSUE A
FREEZING RAIN ADVISORY...ESPECIALLY GIVEN THE MAJORITY OF SNOW
REPORTS. OTHERWISE...ONLY OTHER CONCERN IS THE STRATUS. NAM/RUC
HAVE BEEN DOING THE BEST THUS FAR IN THE LOW LEVEL RH PROGS
MATCHING UP WITH THE STRATUS. BOTH SUGGEST THE AREA STAYS CLOUDY
TODAY...WHICH MAKES SENSE WITH 925-950MB WINDS NORTHEAST TO NORTH.
TONIGHT...THERE COULD BE SOME BREAK UP...ESPECIALLY ALONG THE
NORTHWEST EDGE OF THE FORECAST AREA LATE TONIGHT AS 925MB WINDS
BACK TO THE NORTHWEST AT 12Z. GIVEN THE COLD NATURE OF THE AIRMASS
IN PLACE...ANY CLEARING COULD CAUSE TEMPERATURES TO TANK INTO THE
SINGLE DIGITS. MEANWHILE...CLOUDY AREAS WOULD STAY WARMER IN THE
TEENS AND 20S. NEEDLESS TO SAY...TRICKY LOW TEMPERATURE FORECAST
FOR TONIGHT. GENERALLY FOLLOWED A BLEND OF GUIDANCE FOR HIGHS
TODAY.
TUESDAY THROUGH WEDNESDAY NIGHT...UPPER LEVEL PATTERN IS FORECAST TO
UNDERGO SOME CHANGE DURING THIS PERIOD...IN RESPONSE TO A POWERFUL
UPPER LEVEL TROUGH DIGGING DOWN THROUGH CENTRAL CANADA. AS THIS
TROUGH DIGS SOUTHWARD IT WILL HELP TO PUSH THE TROUGH APPROACHING
THE AREA TONIGHT THROUGH ON TUESDAY...GIVE A BRIEF PERIOD OF UPPER
RIDGING ON TUESDAY NIGHT...THEN CAUSE THE UPPER FLOW TO TURN ZONAL
FOR THE REST OF THE PERIOD. AS THE UPPER TROUGH MOVES THROUGH THE
AREA ON TUESDAY...WHICH MEANS THE SURFACE RIDGE WILL DO THE SAME...
ANTICIPATING SKIES TO CLEAR NORTHWEST TO SOUTHEAST. ALTHOUGH MORE
SUN IS EXPECTED...THE 850MB TEMPS FALL TO -10 TO -12C...SO HIGHS
WILL ACTUALLY END UP COOLER THAN TODAY. MOSTLY CLEAR AND COOL
CONDITIONS CONTINUE TUESDAY NIGHT THANKS TO SUBSIDENCE UNDER THE
UPPER RIDGING. A 5-10 KT SOUTHWEST WIND WILL HELP KEEP TEMPERATURES
FROM TANKING BELOW ZERO TUESDAY NIGHT...THOUGH THE WIND IS EXPECTED
TO DROP WIND CHILLS INTO THE SINGLE DIGITS BELOW ZERO. A BRIEF WARM
UP IS FORECAST FOR WEDNESDAY WITH 850MB TEMPS CLIMBING UP TO AROUND
-6C AT 18Z. HOWEVER...A COLD FRONT COMING THROUGH THE ZONAL FLOW
LOOKS TO CROSS LATE IN THE DAY...BRINGING AN INCREASE OF MID-HIGH
CLOUDS BEHIND IT. AS WE GO THROUGH WEDNESDAY NIGHT...THE 05.00Z
GFS/CANADIAN/NAM ALL WANT TO PRODUCE SOME LIGHT PRECIPITATION OUT OF
THESE CLOUDS...LIKELY A RESULT OF SOME MID-LEVEL FRONTOGENESIS. NOT
QUITE SOLD ON THIS PRECIPITATION YET...ESPECIALLY WITH THE 05.00Z
ECMWF STILL DRY AND REALLY THE FIRST SIGNAL OF IT. THEREFORE...HAVE
ONLY INCREASED CLOUD COVER AT THIS TIME. THE CLOUDS SHOULD HELP KEEP
TEMPERATURES UP SOME WEDNESDAY NIGHT. FOLLOWED A BLEND OF GUIDANCE
THEN.
.LONG TERM...THURSDAY THROUGH SUNDAY NIGHT
314 AM CST MON DEC 5 2011
05.00Z ECMWF/GFS/CANADIAN AND GFS ENSEMBLES REMAIN IN PRETTY GOOD
AGREEMENT FOR THE LONG TERM FORECAST...BOTH BETWEEN EACH RUN AND
WHAT WAS SEEN YESTERDAY...LEADING TO ABOVE AVERAGE CONFIDENCE. A
SHORTWAVE TROUGH COMING AROUND THE POWERFUL CENTRAL CANADA TROUGH IS
PROGGED TO DROP INTO THE NORTHERN PLAINS THURSDAY...CROSSING THE
AREA THURSDAY NIGHT INTO FRIDAY. THERE REMAINS SOME SIGNALS OF A
MID-LEVEL FRONTOGENESIS BAND AND UPPER JET INDUCED PRECIPITATION AS
THIS SHORTWAVE TROUGH APPROACHES THE AREA. HOWEVER...A CONSENSUS OF
THE MODELS HAS SHOWN A SHIFT SOUTH...SUCH THAT IT CROSSES MOSTLY THE
SOUTHERN HALF OF IOWA AND NORTHERN ILLINOIS DURING THURSDAY NIGHT.
NOTE...THE NEW 05.00Z ECMWF HAS SHIFTED BACK NORTH...BUT NOT ENOUGH
CONFIDENCE EXISTS TO PUT CHANCES FARTHER NORTH YET. AFTER THIS...IT
LOOKS LIKE A SOLID DRY FORECAST HEADING INTO THE WEEKEND AS THE
UPPER FLOW TRANSITIONS TO ZONAL. SHOULD SEE A WARMING TREND TOO AS
DOWNSLOPING MOTION OFF THE ROCKIES OF PACIFIC AIR CAUSES
TEMPERATURES TO MODIFY. SO AFTER A CHILLY FRIDAY AND FRIDAY NIGHT
WITH 850MB TEMPS PROGGED AS COLD AS -20C...THESE WILL WARM UP
DRAMATICALLY...REACHING TO 0 TO +2C BY SUNDAY. LOOKING
BEYOND...RIGHT NOW IT APPEARS ABOVE NORMAL TEMPERATURES COULD
PERSIST INTO THE EARLY PORTION OF NEXT WEEK WITH ZONAL FLOW
CONTINUING.
&&
.AVIATION...
1130 PM CST SUN DEC 4 2011
LOW LEVEL SATURATION REMAINS AMPLE FOR THE REST OF TONIGHT THROUGH
MUCH OF MONDAY...ALTHOUGH LATEST 00Z MODEL RUNS SUGGEST SOME PUSH
OF THIS LOW MOISTURE EAST BY THE EVENING. WHILE CIGS WOULD IMPROVE
TO VFR...SOME MID CLOUDS WILL ALREADY BE RETURNING AHEAD OF AN UPPER
LEVEL SHORTWAVE TROUGH. CONFIDENCE IS SHAKY IN JUST HOW SOON
KRST/KLSE WILL BREAK OUT OF THE MVFR CIGS...AND WILL SHOOT FOR 00Z
RIGHT NOW. ANTICIPATE THAT THAT TIMING WILL NEED TO BE REFINED.
COULD SEE A FEW FLURRIES OUT OF THE CLOUDS OVERNIGHT THROUGH
MONDAY...BUT DO NOT ANTICIPATE ANY ACCUMULATION OR APPRECIABLE /IF
ANY/ REDUCTIONS TO VSBYS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
314 AM CST MON DEC 5 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...RIECK
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1142 PM CST SUN DEC 4 2011
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.UPDATED...FREEZING DRIZZLE APPEARS TO BE MORE WIDESPREAD OVER
WEST CENTRAL WISCONSIN WITH SOME MID LEVEL DRYING WORKING
SOUTHWARD. MOIST CYCLONIC FLOW OVER EASTERN WISCONSIN WOULD
DIMINISH THREAT. SOME OBSERVATIONS OVER CENTRAL WISCONSIN WERE
REPORTING SOME FLURRIES AND LIGHT MIX SO WILL ADD A SMALL MENTION
TO THE FORECAST IN THE AREA. LESS OF A THREAT OF ZL EAST OF AUW
WITH SURFACE TEMPS STILL ABOVE FREEZING. CALL TO SOME LAW
ENFORCEMENTS DEPARTMENTS IN CENTRAL WISCONSIN REPORTING LIGHT
SNOW. OTHERWISE THIS BAND OF LIGHT SNOW WITH WEAK TROUGH AND
SURFACE REFLECTION WILL CONTINUE TO DROP SOUTH OVER CENTRAL AND
EAST CENTRAL WISCONSIN OVERNIGHT.
TDH
&&
.PREV DISCUSSION...ISSUED AT 535 PM CST SUN DEC 4 2011...
SHORT TERM...TONIGHT AND MONDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A DOUBLE
BARRELED LOW PRESSURE MOVING ACROSS THE ONTARIO-QUEBEC BORDER AND
THE STRAITS OF MACKINAC...AND A COLD FRONT STRETCHING FROM NORTHERN
LOWER MICHIGAN TO THE SOUTHERN MISSISSIPPI VALLEY. WITH NORTHWEST
FLOW IN PLACE AND DELTA T/S INCREASING TO 14C...CLOUD COVER HAS BEEN
STUBBORN TO DISSIPATE THOUGH PRECIP HAS EXITED TO THE NORTHEAST BY
MIDDAY. A SURFACE TROUGH IS TRYING TO DEVELOP OVER NORTHEAST AND CENTRAL
WISCONSIN THIS AFTERNOON AND A FEW SNOW SHOWERS/FLURRIES HAVE
DEVELOPED OVER THE PAST HOUR. SOME CLEARING NOTED OVER NORTHERN
MINNESOTA WHERE DEWPOINTS HAVE FALLEN TO THE LOWER TEENS. WITH
NORTHERLY FLOW IN PLACE OVER THE NEXT 24 HOURS...SMALL PRECIP
CHANCES AND CLOUD TRENDS ARE THE MAIN FORECAST CONCERNS.
TONIGHT... AS HIGH PRESSURE BUILDS OVER THE NORTHERN PLAINS...WEAK
CYCLONIC FLOW WILL LINGER ACROSS THE REGION. LOW LEVEL FLOW WILL
VEER FROM THE NORTHWEST TO THE NORTH...WHICH WILL KEEP MOISTURE
STREAMING OFF LAKE SUPERIOR. AS A RESULT...SCT LAKE EFFECT SNOW
SHOWERS WILL PREVAIL OVER THE SNOW BELT OF N-C WISCONSIN FOR THE
ENTIRE NIGHT. FARTHER SOUTH...A WEAK SURFACE TROUGH WILL MOVE SOUTH
OVER CENTRAL WISCONSIN THIS EVENING. MOISTURE DEPTH WILL EXTEND
BEYOND 800MB AND -10C...SO IT SEEMS PLAUSIBLE THAT FLURRIES OR VERY
LIGHT SNOW SHOWERS ARE POSSIBLE ALONG THE TROUGH. HAVE ADDED
SLIGHTLY MORE TEMPORAL RESOLUTION TO ACCOUNT FOR THIS.
OTHERWISE...DO NOT SEE MUCH OF AN OPPORTUNITY FOR CLEARING...EXCEPT
IN THE DOWN SLOPING REGIONS OF NORTHEAST WISCONSIN WHERE SOME HOLES
MAY DEVELOP...ESPECIALLY LATE TONIGHT. LOWS IN THE UPPER TEENS
NORTH TO UPPER 20S SOUTHEAST.
MONDAY...ONLY SOME SUBTLE CHANGES HEADING INTO MONDAY. SHORTWAVE
ENERGY OVER THE PLAINS WILL LIFT TO THE NORTHEAST OVER NW
WISCONSIN...BUT WITH VERY LITTLE IMPACT ON OUR WEATHER. WILL
CONTINUE TO HAVE NORTHERLY FLOW TOMORROW WITH SOME MINOR COLD
ADVECTION THAT WILL DROP 850MB TEMPS IN THE NEGATIVE LOW TO MID
TEENS. LIGHT LAKE EFFECT SNOW SHOWERS WILL PREVAIL OVER THE SNOW
BELT OF N-C WISCONSIN...WHILE MOSTLY CLOUDY CONDITIONS WILL BE THE
RULE ELSEWHERE. HIGHS IN THE MIDDLE 20S NORTH TO MIDDLE 30S
SOUTHEAST.
LONG TERM...MONDAY NIGHT THROUGH NEXT SUNDAY...THE MAIN FCST
CONCERN IS THE ARRIVAL OF COLDER ARCTIC AIR LATE IN THE NEXT WORK
WEEK.
A STRONG UPPER RIDGE WILL COVER THE EASTERN PACIFIC...SOUTHWEST
CANADA AND THE WEST COAST OF THE U.S. EARLY IN THE PERIOD...WITH A
POSITIVELY-TILTED UPPER TROF MOVG OUT OF THE NORTHERN PLAINS INTO
THE WESTERN GREAT LAKES. THIS UPPER TROF WILL MOVE THROUGH
WISCONSIN ON MONDAY NIGHT AND TUESDAY...BUT WITH A SFC RIDGE OF
HIGH PRESSURE IN PLACE...EXPECT MINIMAL IMPACT ON OUR WEATHER.
SHORT-WAVE ENERGY TOPPING THE WESTERN RIDGE AND DIVING INTO THE
NORTHERN PLAINS WILL HELP TO CARVE A BROAD TROF OVER THE CENTRAL
U.S. BY THURSDAY. A SURGE OF ARCTIC AIR IS EXPECTED TO ARRIVE IN
WI ON THURSDAY...WITH H8 TEMPS PLUMMETING TO AROUND -20 C LATE
THURSDAY NIGHT INTO FRIDAY. THIS WILL LEAD TO OUR COLDEST
TEMPERATURES SO FAR THIS SEASON. THE COLD SNAP WILL BE BRIEF...
AS SOUTHWEST WINDS DEVELOP IN THE WAKE OF THE RETREATING ARCTIC
HIGH OVER THE WEEKEND.
A LARGE RIDGE OF HIGH PRESSURE WILL BUILD INTO NW WI ON MONDAY
NIGHT...THEN MOVE THROUGH GRB CWA ON TUESDAY. LINGERING LAKE-EFFECT
SNOW SHOWERS OVER NC WI SHOULD COME TO AN END AS THE RIDGE AXIS
ARRIVES ON TUESDAY.
A WEAK COLD FRONT IS EXPECTED TO MOVE THROUGH THE REGION ON
WEDNESDAY...WITH A STRONGER ARCTIC FRONT ARRIVING ON THURSDAY.
THE ECMWF HAS BACKED OFF ON THE POTENTIAL FOR SNOW ALONG THE
ARCTIC FRONT ON THU NGT/FRI...AND IS FOCUSING FARTHER SE...FROM
SOUTHERN WI INTO LOWER MICHIGAN. WILL NEED TO KEEP AN EYE ON THIS
OVER THE NEXT FEW DAYS TO SEE IF THIS TREND WILL HOLD. CONFIDENCE
IS FAIRLY HIGH FOR THE ARRIVAL OF MUCH COLDER TEMPERATURES LATE IN
THE WORK WEEK...ALTHOUGH THE COLD IS EXPECTED TO BE SHORT-LIVED.
A WARM FRONT IS EXPECTED TO ARRIVE ON SUNDAY...WITH TEMPERATURES
CLIMBING BACK TO ABOVE NORMAL.
DESPITE THE PRESENCE OF A COLD AIR MASS FROM WEDNESDAY THROUGH
SATURDAY...WIND TRAJECTORIES WILL NOT BE FAVORABLE FOR LK-EFFECT
SNOW.
&&
.AVIATION...A WEAK SHORT WAVE WITH SUBTLE SURFACE REFLECTION
CONTINUES TO DROP SOUTH OVER CENTRAL AND EAST CENTRAL WISCONSIN
THIS EVENING. A BAND OF MVFR VSBYS DUE TO SNOW ASSOCIATED WITH
THIS FEATURE WILL CONTINUE TO DROP SOUTH OVERNIGHT...PERHAPS
FINALLY DEPARTING SOUTHERN AREAS AFTER 10Z. OTHERWISE MVFR CIGS
WITH VFR VSBYS TO DOMINATE TO REGION ON MONDAY. A FEW FLURRIES MAY
LINGER IN THE MORNING HOURS.
TDH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
233 AM CST WED DEC 7 2011
.DISCUSSION...
900 PM CST
AS ANTICIPATED...CLOUDS ARE MAKING IT EXTRA CHALLENGING WITH THE
TEMPERATURE FORECAST TONIGHT. THE CLEARING WAS SHORT-LIVED...WITH
CLOUDS BOTH EXPANDING AND ADVECTING BACK EAST WITHIN AND JUST ON
THE BACKSIDE OF THE LOW-LEVEL RIDGE. AN UPPER LEVEL TROUGH ALOFT
OVER THE AREA IS CONTINUING TO SHEAR OUT...WITH SUPPRESSION
APPARENTLY INCREASING LOOKING AT THE WATER VAPOR SATELLITE. THE
EVENING DVN AND ILX SOUNDINGS DEPICTED A FAIRLY DEEP 3000 FT LAYER
AT SATURATED OR NEAR-SATURATED...AND THERE ARE FEW SIGNS OF HOLES
EXISTING WITHIN THE CLOUD RIBBON. DESPITE THAT...THE BACK EDGE IS
PROGRESSING...LOCATED ABOUT 100 MILES WEST OF THE MISSISSIPPI
RIVER AROUND 9 PM. THE NAM AND RUC ANALYSIS OF 925-850MB MOISTURE
CAPTURE THIS WELL AND THE PROGRESSION OF THIS. THEIR DRYING
FORECAST COMES ACROSS NORTHERN IL FROM 3 AM THROUGH
DAYBREAK...COINCIDENT WITH THEIR DEPICTION OF HIGHER Q-VECTOR
DIVERGENCE /A PROXY FOR THE SUPPRESSION MENTIONED EARLIER/. THE
LAMP GUIDANCE HAS A VERY GOOD HANDLE ON THE STEADY TEMPERATURES
UNDER THE CLOUD COVER AND SHOW A LATE NIGHT DROP...ESPECIALLY IN
THE WESTERN FORECAST AREA. HAVE STEERED THIS AND THE RUC TREND
INTO THE FORECAST. OVERALL...MINIMUMS ARE SLIGHTLY WARMER FOR MOST
PLACES...A FEW DEGREES TOTAL FOR SOUTH AND EAST OF CHICAGO WHICH
SHOULD SEE THE CLOUDS ARRIVE SHORTLY AND LAST ALL THE WAY THROUGH
DAYBREAK.
MTF
PREVIOUS DISCUSSION...
417 PM CDT
SHORT TERM...THIS AFTERNOON THROUGH FRIDAY
MAIN CONCERN THIS PORTION OF THE FORECAST CENTERS ON LIGHT SNOW
CHANCES THURSDAY NIGHT INTO EARLY FRIDAY AND THEN BLAST OF ARCTIC
AIR FRIDAY INTO EARLY SATURDAY.
AFTERNOON WATER VAPOR IMAGERY SHOWS MID LEVEL TROUGHING ACROSS THE
REGION...WHILE AT THE SURFACE...HIGH PRESSURE STRETCHES FROM THE
WESTERN GREAT LAKES SOUTHWEST TO THE SOUTHERN PLAINS. ON VISIBLE
SATELLITE...EVER PRESENT STRATUS ACTUALLY HAS ERODED A BIT THIS
AFTERNOON FROM THE NORTH AS HIGH PRESSURE BUILDS IN. SUSPECT HOWEVER
THAT STRATUS WILL TEMPORARILY RETURN THIS EVENING AS FLOW BECOMES
NORTHERLY THEN WESTERLY. MODEL RH PROGS SHOW PLENTIFUL MOISTURE
BELOW 800 MB UNTIL LATER TONIGHT. THEN EXPECT THE REMAINING OVERCAST
TO ERODE FROM NORTHWEST. WITH CHILLY AIR MASS IN PLACE...TIMING OF
CLEARING TONIGHT WILL HAVE IMPACT ON LOW TEMPERATURES. THINK THAT
SKIES WILL CLEAR ENOUGH BY TOMORROW MORNING SO THAT...ALONG
WITH LIGHT WINDS...TEMPERATURES WILL BE ABLE TO PLUMMET TO THE UPPER
TEENS ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS. THE
REMAINDER OF THE AREA CAN EXPECT LOW TO MID 20S...WITH UPPER 20S IN
AND NEAR DOWNTOWN CHICAGO. WENT CLOSE TO MAV/MET GUIDANCE FOR LOWS
AND SLIGHTLY COLDER THAN PREVIOUS ISSUANCE.
WEDNESDAY WILL START OUT MOSTLY SUNNY...BUT CLOUDS MAY INCREASE JUST
A BIT IN THE AFTERNOON AS A COLD FRONT SWINGS THROUGH THE AREA
DURING THE AFTERNOON. LOW LEVELS WILL BE EXTREMELY DRY SO NO
PRECIPITATION IS FORECAST WITH THE FROPA. HIGHS WILL TOP OUT NEAR OR
JUST BELOW AVERAGE...LOW 30S OVER NORTH CENTRAL ILLINOIS AND MID 30S
FOR THE REMAINDER OF THE AREA. FROPA WILL SEND REINFORCING SHOT OF
COLDER AIR ACROSS REGION...AS TEMPERATURES COOL AT H85 WEDNESDAY
NIGHT TO ROUGHLY -8C. PRESSURE GRADIENT WILL REMAIN TIGHT ENOUGH TO
KEEP A WESTERLY BREEZE GOING...WITH LOWS LIKELY SIMILAR TO TONIGHT.
THURSDAY WILL BE A FEW DEGREES COOLER THAN WEDNESDAY...WITH CLOUDS
INCREASING FROM THE WEST AS A WAVE DEVELOPS WEST OF THE AREA ALONG
A TIGHT BAROCLINIC ZONE...WITH THE BULK OF ARCTIC AIR OVER THE
NORTHERN PLAINS AND UPPER MIDWEST NORTH OF OUR AREA. ON THURSDAY
NIGHT...DIGGING H5 TROUGH WILL SPAWN A WEAK SURFACE LOW WHICH WILL
TRACK ACROSS THE NORTHERN GREAT LAKES AND SEND AN ARCTIC
FRONTAL BOUNDARY TOWARD THE AREA. THE FRONTOGENETIC FORCED WAVE
ALONG THE ARCTIC FRONT WILL TRACK ALONG THE TIGHTEST THERMAL PACKING
TO NEAR OR OVER OUR AREA. MOST GUIDANCE...WITH THE EXCEPTION
OF THE NAM AND SREF HAVE COME INTO DECENT AGREEMENT ON A BAND OF
LIGHT QPF OVER ALL OF NORTHERN ILLINOIS AND NORTHWEST INDIANA ON
THURSDAY NIGHT INTO EARLY FRIDAY. TIME HEIGHTS AND SOUNDINGS
CONTINUE TO SHOW ADEQUATE SATURATION AND LIFT INTO THE FAVORABLE
DENDRITIC GROWTH AREA. THE RIGHT ENTRANCE REGION OF JET MAY PROVIDE
SOME ENHANCED LIFT. WITH COLD TEMPERATURES IN PLACE...EXPECTING 20:1
RATIO...WHICH WOULD RESULT IN THE FIRST LIGHT ACCUMULATING SNOWFALL
OF THE SEASON FOR MUCH OF THE AREA. AT THIS POINT...POTENTIAL EXISTS
FOR SOME LOCATIONS TO SEE IN EXCESS OF ONE INCH OF SNOWFALL. NOT
HIGH CONFIDENCE YET ON THIS FEATURE...SO DID STAY WITH CHANCE POPS
AS OPPOSED TO HIGHER POPS. IT MAY COME DOWN TO VERY CLOSE TO THE
EVENT UNTIL THE PART OF THE AREA WITH THE BEST FORCING FOR LIGHT
SNOW IS ASCERTAINED. ONCE WAVE QUICKLY SHIFTS EAST THROUGH THE
AREA...THE BIG STORY WILL BE SHARP COLD ADVECTION...WITH MINUS
TEEN TEMPERATURES AT H85 POISED TO POUR INTO AREA. WENT WITH BLENDED
MODEL GUIDANCE FOR LOWS EARLY FRIDAY MORNING...WHICH YIELDS UPPER
TEENS FAR NORTHERN ILLINOIS TO THE LOWER AND MIDDLE 20S FARTHER
SOUTH.
WITH STRONG COLD AIR ADVECTION ONGOING ON FRIDAY...IT WILL BE VERY
DIFFICULT TO RECOVER MUCH FROM THESE LOW TEMPERATURES. MODELS DIFFER
ON HOW COLD WE GET AT H85 AS THERMAL TROUGH REACHES AREA ON FRIDAY.
BUT THE GENERAL RANGE IS ABOUT -15C TO -20C. THUS WENT COLDER THAN
PREVIOUS FORECAST ISSUANCE BY SEVERAL DEGREES FOR FRIDAY...WITH LOW
20S FAR NORTH AND MIDDLE AND UPPER 20S ALONG AND SOUTH OF INTERSTATE
80. SOME LIGHT SNOW MAY LINGER OVER THE EASTERN PORTION OF THE
FORECAST AREA BEFORE SHIFTING EAST BY THE AFTERNOON.
LONG TERM...FRIDAY NIGHT THROUGH TUESDAY NIGHT
GUIDANCE HAS CONTINUED TO TREND COLDER WITH LOW TEMPERATURES
FRIDAY NIGHT...CAPTURED WELL BY A BLEND OF MODEL GUIDANCE AND
PREVIOUS FORECAST. ARCTIC HIGH WILL STRETCH ACROSS AREA...ALLOWING
FOR LIGHT WINDS AND STRONG RADIATIONAL COOLING OVERNIGHT. IF MINOR
SNOW COVER IS IN PLACE...FORECAST LOWS IN THE LOWER TO MIDDLE TEENS
FOR MUCH OF THE AREA OUTSIDE THE CHICAGO HEAT ISLAND MAY STILL END
UP BEING A FEW DEGREES TOO HIGH. SATURDAY WILL START OUT QUITE
COLD...BUT WARM ADVECTION ALOFT AND SOUTHWESTERLY FLOW AT THE
SURFACE WILL ALLOW FOR SOME RECOVERY TO THE UPPER 20S TO AROUND 30
DEGREES. FOR THE REMAINDER OF THE EXTENDED...THE AREA WILL REMAIN
INFLUENCED BY RIDGING OVER THE EASTERN CONUS...SO SOUTHWESTERLY
FLOW...DRY CONDITIONS...AND TEMPERATURES RETURNING TO SLIGHTLY ABOVE
NORMAL...OR AROUND 40 DEGREES...CAN BE EXPECTED. THERE MAY BE A COLD
FRONTAL PASSAGE DAY 6 OR DAY 7...BUT EVEN THAT MAY BE A DRY FROPA.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 08Z...
* CIG TRENDS THROUGH INTO THE MORNING HOURS
SHEA
//DISCUSSION...UPDATED 08Z...
NORTHERN EDGE OF STRATUS APPEARS TO BE ACCELERATING SOUTH...AND
NUDGED UP THE TIMING OF WHEN THE MVFR CIGS SHOULD POP TO VFR.
TIMING MAY STILL NEED TO BE TWEAKED FASTER IF EROSION CONTINUES AS
FAST IT IS CURRENTLY TRENDING. OTHERWISE THE NEXT CONCERN WILL BE WITH HOW
FAR INTO THE TRACON THE HIGH IFR / LOW MVFR CIGS WILL ADVANCE BEFORE
CONDITIONS RAPIDLY IMPROVE. KFEP FELL TO 015 FOR A SHORT TIME
BEFORE MOVING BACK INTO MID RANGE MVFR... AND HAVE A FEELING THAT
WILL BE THE TREND WHEN CIGS FALL. DURATION NOT LOOKING TO BE TOO
LONG AND MODIFIED THE TAFOR TO INCLUDE THE LOWER CLOUDS IN A TEMPO
VS PREVAILING.
SHEA
//DISCUSSION...UPDATED 06Z...
A RIDGE OF HIGH PRESSURE IS SINKING SOUTHEAST ACROSS THE FORECAST
AREA...WITH LIGHT AND VARIABLE WINDS ACROSS MUCH OF NORTHERN
ILLINOIS. WHILE WE DID CLEAR OUT BRIEFLY EARLIER THIS
EVENING...STRATUS HAS ADVANCED EASTWARD ALONG THE RIDGE AXIS AND
EXTENDS AS FAR WEST AS EASTERN IOWA LATE THIS EVENING. SURFACE OBS
SHOW MVFR DECK ADVANCING EAST ACROSS THE RIVER...WITH IFR CIGS
BECOMING MORE WIDESPREAD. DONT SEE ANY REASON WHY CLOUDS WOULD
SCATTER/CLEAR BEFORE DAYBREAK TOMORROW AS ANY SUBSIDENCE ACROSS THE
AREA WOULD ONLY ENHANCE THE INVERSION TO HOLD IN THE MOISTURE...THUS
BUMPED BACK TIMING OF CLEARING TIL MID MORNING AND LOWERED CIGS TO
015 LATE TONIGHT. CANT RULE OUT IFR CONDITIONS REACHING THE CHICAGO
TERMINALS...BUT WITH GUIDANCE STILL NOT LOCKING ONTO THE LOW CIGS
DONT HAVE MUCH FEEL FOR HOW LOW CIGS WILL DROP OR WHEN...THOUGH RUC
SOUNDINGS DO SHOW CIGS CLOSE TO IFR AROUND 12Z. HAVE SOMEWHAT BETTER
CONFIDENCE AT RFD WITH MET/RUC GUIDANCE HONING IN ON 09Z.
ONCE RIDGE AXIS PASSES THROUGH...WINDS WILL BEGIN TO INCREASE OUT OF
THE WEST...WSW. GUSTS WILL PICK UP DURING THE AFTERNOON HOURS
WEDNESDAY AHEAD OF AN APPROACHING COLD FRONT WITH MODEST MIXING
BRINGING DOWN LOW 20KT WINDS. PRECIP WILL STAY NORTH OF THE
CHICAGO/ROCKFORD TERMINALS. DO EXPECT CLOUD COVER TO ONCE AGAIN
INCREASE...BUT SHOULD STAY VFR.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 08Z...
* HIGH CONFIDENCE IN WIND FORECAST
* MODERATE TO HIGH CONFIDENCE IN VFR CIGS DROPPING TO MID-HIGH
MVFR...LOW CONFIDENCE IN FALLING BELOW 1.5 KFT
SHEA
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY...SLIGHT CHANCE OF SNOW OVERNIGHT. IFR/MVFR POSSIBLE.
FRIDAY...VFR.
SATURDAY...MVFR POSSIBLE.
SUNDAY...VFR.
MONDAY...VFR.
BMD
&&
.MARINE...
230 AM CST
HIGH PRESSURE EXTENDING FROM NEWFOUNDLAND...THROUGH THE EASTERN
GREAT LAKES...TO TEXAS WILL CONTINUE TO BUILD SLOWLY EASTWARD OVER
THE NEXT FEW DAYS. MEANWHILE...LOW PRESSURE OVER NORTHERN HUDSON
BAY WILL DRAG A COLD FRONT ACROSS LAKE MICHIGAN LATE THIS
AFTERNOON AND EARLY THIS EVENING. A SURGE OF MUCH COOLER
AIR...COMBINED WITH HIGH PRESSURE BUILDING OUT OF THE NORTHERN
ROCKIES AND INTO THE NORTHERN PLAINS WILL LEAD TO QUICKLY
INCREASING...GENERALLY WESTERLY...WINDS OVER LAKE MICHIGAN. BRISK
WESTERLY WINDS WILL PERSIST OVER THE LAKE INTO SATURDAY. BY
SATURDAY NIGHT...THE HIGH WILL DROP INTO THE OHIO VALLEY AS LOW
PRESSURE DROPS OUT OF THE CANADIAN NORTHWEST TERRITORIES AND
TRACKS ACROSS THE PRAIRIE REACHES JAMES BAY BY SUNDAY MORNING.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744...6 PM
WEDNESDAY TO 10 PM THURSDAY.
SMALL CRAFT ADVISORY...LMZ745...6 PM WEDNESDAY TO 10 AM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
207 AM CST WED DEC 7 2011
.DISCUSSION...
900 PM CST
AS ANTICIPATED...CLOUDS ARE MAKING IT EXTRA CHALLENGING WITH THE
TEMPERATURE FORECAST TONIGHT. THE CLEARING WAS SHORT-LIVED...WITH
CLOUDS BOTH EXPANDING AND ADVECTING BACK EAST WITHIN AND JUST ON
THE BACKSIDE OF THE LOW-LEVEL RIDGE. AN UPPER LEVEL TROUGH ALOFT
OVER THE AREA IS CONTINUING TO SHEAR OUT...WITH SUPPRESSION
APPARENTLY INCREASING LOOKING AT THE WATER VAPOR SATELLITE. THE
EVENING DVN AND ILX SOUNDINGS DEPICTED A FAIRLY DEEP 3000 FT LAYER
AT SATURATED OR NEAR-SATURATED...AND THERE ARE FEW SIGNS OF HOLES
EXISTING WITHIN THE CLOUD RIBBON. DESPITE THAT...THE BACK EDGE IS
PROGRESSING...LOCATED ABOUT 100 MILES WEST OF THE MISSISSIPPI
RIVER AROUND 9 PM. THE NAM AND RUC ANALYSIS OF 925-850MB MOISTURE
CAPTURE THIS WELL AND THE PROGRESSION OF THIS. THEIR DRYING
FORECAST COMES ACROSS NORTHERN IL FROM 3 AM THROUGH
DAYBREAK...COINCIDENT WITH THEIR DEPICTION OF HIGHER Q-VECTOR
DIVERGENCE /A PROXY FOR THE SUPPRESSION MENTIONED EARLIER/. THE
LAMP GUIDANCE HAS A VERY GOOD HANDLE ON THE STEADY TEMPERATURES
UNDER THE CLOUD COVER AND SHOW A LATE NIGHT DROP...ESPECIALLY IN
THE WESTERN FORECAST AREA. HAVE STEERED THIS AND THE RUC TREND
INTO THE FORECAST. OVERALL...MINIMUMS ARE SLIGHTLY WARMER FOR MOST
PLACES...A FEW DEGREES TOTAL FOR SOUTH AND EAST OF CHICAGO WHICH
SHOULD SEE THE CLOUDS ARRIVE SHORTLY AND LAST ALL THE WAY THROUGH
DAYBREAK.
MTF
PREVIOUS DISCUSSION...
417 PM CDT
SHORT TERM...THIS AFTERNOON THROUGH FRIDAY
MAIN CONCERN THIS PORTION OF THE FORECAST CENTERS ON LIGHT SNOW
CHANCES THURSDAY NIGHT INTO EARLY FRIDAY AND THEN BLAST OF ARCTIC
AIR FRIDAY INTO EARLY SATURDAY.
AFTERNOON WATER VAPOR IMAGERY SHOWS MID LEVEL TROUGHING ACROSS THE
REGION...WHILE AT THE SURFACE...HIGH PRESSURE STRETCHES FROM THE
WESTERN GREAT LAKES SOUTHWEST TO THE SOUTHERN PLAINS. ON VISIBLE
SATELLITE...EVER PRESENT STRATUS ACTUALLY HAS ERODED A BIT THIS
AFTERNOON FROM THE NORTH AS HIGH PRESSURE BUILDS IN. SUSPECT HOWEVER
THAT STRATUS WILL TEMPORARILY RETURN THIS EVENING AS FLOW BECOMES
NORTHERLY THEN WESTERLY. MODEL RH PROGS SHOW PLENTIFUL MOISTURE
BELOW 800 MB UNTIL LATER TONIGHT. THEN EXPECT THE REMAINING OVERCAST
TO ERODE FROM NORTHWEST. WITH CHILLY AIR MASS IN PLACE...TIMING OF
CLEARING TONIGHT WILL HAVE IMPACT ON LOW TEMPERATURES. THINK THAT
SKIES WILL CLEAR ENOUGH BY TOMORROW MORNING SO THAT...ALONG
WITH LIGHT WINDS...TEMPERATURES WILL BE ABLE TO PLUMMET TO THE UPPER
TEENS ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS. THE
REMAINDER OF THE AREA CAN EXPECT LOW TO MID 20S...WITH UPPER 20S IN
AND NEAR DOWNTOWN CHICAGO. WENT CLOSE TO MAV/MET GUIDANCE FOR LOWS
AND SLIGHTLY COLDER THAN PREVIOUS ISSUANCE.
WEDNESDAY WILL START OUT MOSTLY SUNNY...BUT CLOUDS MAY INCREASE JUST
A BIT IN THE AFTERNOON AS A COLD FRONT SWINGS THROUGH THE AREA
DURING THE AFTERNOON. LOW LEVELS WILL BE EXTREMELY DRY SO NO
PRECIPITATION IS FORECAST WITH THE FROPA. HIGHS WILL TOP OUT NEAR OR
JUST BELOW AVERAGE...LOW 30S OVER NORTH CENTRAL ILLINOIS AND MID 30S
FOR THE REMAINDER OF THE AREA. FROPA WILL SEND REINFORCING SHOT OF
COLDER AIR ACROSS REGION...AS TEMPERATURES COOL AT H85 WEDNESDAY
NIGHT TO ROUGHLY -8C. PRESSURE GRADIENT WILL REMAIN TIGHT ENOUGH TO
KEEP A WESTERLY BREEZE GOING...WITH LOWS LIKELY SIMILAR TO TONIGHT.
THURSDAY WILL BE A FEW DEGREES COOLER THAN WEDNESDAY...WITH CLOUDS
INCREASING FROM THE WEST AS A WAVE DEVELOPS WEST OF THE AREA ALONG
A TIGHT BAROCLINIC ZONE...WITH THE BULK OF ARCTIC AIR OVER THE
NORTHERN PLAINS AND UPPER MIDWEST NORTH OF OUR AREA. ON THURSDAY
NIGHT...DIGGING H5 TROUGH WILL SPAWN A WEAK SURFACE LOW WHICH WILL
TRACK ACROSS THE NORTHERN GREAT LAKES AND SEND AN ARCTIC
FRONTAL BOUNDARY TOWARD THE AREA. THE FRONTOGENETIC FORCED WAVE
ALONG THE ARCTIC FRONT WILL TRACK ALONG THE TIGHTEST THERMAL PACKING
TO NEAR OR OVER OUR AREA. MOST GUIDANCE...WITH THE EXCEPTION
OF THE NAM AND SREF HAVE COME INTO DECENT AGREEMENT ON A BAND OF
LIGHT QPF OVER ALL OF NORTHERN ILLINOIS AND NORTHWEST INDIANA ON
THURSDAY NIGHT INTO EARLY FRIDAY. TIME HEIGHTS AND SOUNDINGS
CONTINUE TO SHOW ADEQUATE SATURATION AND LIFT INTO THE FAVORABLE
DENDRITIC GROWTH AREA. THE RIGHT ENTRANCE REGION OF JET MAY PROVIDE
SOME ENHANCED LIFT. WITH COLD TEMPERATURES IN PLACE...EXPECTING 20:1
RATIO...WHICH WOULD RESULT IN THE FIRST LIGHT ACCUMULATING SNOWFALL
OF THE SEASON FOR MUCH OF THE AREA. AT THIS POINT...POTENTIAL EXISTS
FOR SOME LOCATIONS TO SEE IN EXCESS OF ONE INCH OF SNOWFALL. NOT
HIGH CONFIDENCE YET ON THIS FEATURE...SO DID STAY WITH CHANCE POPS
AS OPPOSED TO HIGHER POPS. IT MAY COME DOWN TO VERY CLOSE TO THE
EVENT UNTIL THE PART OF THE AREA WITH THE BEST FORCING FOR LIGHT
SNOW IS ASCERTAINED. ONCE WAVE QUICKLY SHIFTS EAST THROUGH THE
AREA...THE BIG STORY WILL BE SHARP COLD ADVECTION...WITH MINUS
TEEN TEMPERATURES AT H85 POISED TO POUR INTO AREA. WENT WITH BLENDED
MODEL GUIDANCE FOR LOWS EARLY FRIDAY MORNING...WHICH YIELDS UPPER
TEENS FAR NORTHERN ILLINOIS TO THE LOWER AND MIDDLE 20S FARTHER
SOUTH.
WITH STRONG COLD AIR ADVECTION ONGOING ON FRIDAY...IT WILL BE VERY
DIFFICULT TO RECOVER MUCH FROM THESE LOW TEMPERATURES. MODELS DIFFER
ON HOW COLD WE GET AT H85 AS THERMAL TROUGH REACHES AREA ON FRIDAY.
BUT THE GENERAL RANGE IS ABOUT -15C TO -20C. THUS WENT COLDER THAN
PREVIOUS FORECAST ISSUANCE BY SEVERAL DEGREES FOR FRIDAY...WITH LOW
20S FAR NORTH AND MIDDLE AND UPPER 20S ALONG AND SOUTH OF INTERSTATE
80. SOME LIGHT SNOW MAY LINGER OVER THE EASTERN PORTION OF THE
FORECAST AREA BEFORE SHIFTING EAST BY THE AFTERNOON.
LONG TERM...FRIDAY NIGHT THROUGH TUESDAY NIGHT
GUIDANCE HAS CONTINUED TO TREND COLDER WITH LOW TEMPERATURES
FRIDAY NIGHT...CAPTURED WELL BY A BLEND OF MODEL GUIDANCE AND
PREVIOUS FORECAST. ARCTIC HIGH WILL STRETCH ACROSS AREA...ALLOWING
FOR LIGHT WINDS AND STRONG RADIATIONAL COOLING OVERNIGHT. IF MINOR
SNOW COVER IS IN PLACE...FORECAST LOWS IN THE LOWER TO MIDDLE TEENS
FOR MUCH OF THE AREA OUTSIDE THE CHICAGO HEAT ISLAND MAY STILL END
UP BEING A FEW DEGREES TOO HIGH. SATURDAY WILL START OUT QUITE
COLD...BUT WARM ADVECTION ALOFT AND SOUTHWESTERLY FLOW AT THE
SURFACE WILL ALLOW FOR SOME RECOVERY TO THE UPPER 20S TO AROUND 30
DEGREES. FOR THE REMAINDER OF THE EXTENDED...THE AREA WILL REMAIN
INFLUENCED BY RIDGING OVER THE EASTERN CONUS...SO SOUTHWESTERLY
FLOW...DRY CONDITIONS...AND TEMPERATURES RETURNING TO SLIGHTLY ABOVE
NORMAL...OR AROUND 40 DEGREES...CAN BE EXPECTED. THERE MAY BE A COLD
FRONTAL PASSAGE DAY 6 OR DAY 7...BUT EVEN THAT MAY BE A DRY FROPA.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 08Z...
* CIG TRENDS THROUGH INTO THE MORNING HOURS
SHEA
//DISCUSSION...UPDATED 08Z...
NORTHERN EDGE OF STRATUS APPEARS TO BE ACCELERATING SOUTH...AND
NUDGED UP THE TIMING OF WHEN THE MVFR CIGS SHOULD POP TO VFR.
TIMING MAY STILL NEED TO BE TWEAKED FASTER IF EROSION CONTINUES AS
FAST IT IS CURRENTLY TRENDING. OTHERWISE THE NEXT CONCERN WILL BE WITH HOW
FAR INTO THE TRACON THE HIGH IFR / LOW MVFR CIGS WILL ADVANCE BEFORE
CONDITIONS RAPIDLY IMPROVE. KFEP FELL TO 015 FOR A SHORT TIME
BEFORE MOVING BACK INTO MID RANGE MVFR... AND HAVE A FEELING THAT
WILL BE THE TREND WHEN CIGS FALL. DURATION NOT LOOKING TO BE TOO
LONG AND MODIFIED THE TAFOR TO INCLUDE THE LOWER CLOUDS IN A TEMPO
VS PREVAILING.
SHEA
//DISCUSSION...UPDATED 06Z...
A RIDGE OF HIGH PRESSURE IS SINKING SOUTHEAST ACROSS THE FORECAST
AREA...WITH LIGHT AND VARIABLE WINDS ACROSS MUCH OF NORTHERN
ILLINOIS. WHILE WE DID CLEAR OUT BRIEFLY EARLIER THIS
EVENING...STRATUS HAS ADVANCED EASTWARD ALONG THE RIDGE AXIS AND
EXTENDS AS FAR WEST AS EASTERN IOWA LATE THIS EVENING. SURFACE OBS
SHOW MVFR DECK ADVANCING EAST ACROSS THE RIVER...WITH IFR CIGS
BECOMING MORE WIDESPREAD. DONT SEE ANY REASON WHY CLOUDS WOULD
SCATTER/CLEAR BEFORE DAYBREAK TOMORROW AS ANY SUBSIDENCE ACROSS THE
AREA WOULD ONLY ENHANCE THE INVERSION TO HOLD IN THE MOISTURE...THUS
BUMPED BACK TIMING OF CLEARING TIL MID MORNING AND LOWERED CIGS TO
015 LATE TONIGHT. CANT RULE OUT IFR CONDITIONS REACHING THE CHICAGO
TERMINALS...BUT WITH GUIDANCE STILL NOT LOCKING ONTO THE LOW CIGS
DONT HAVE MUCH FEEL FOR HOW LOW CIGS WILL DROP OR WHEN...THOUGH RUC
SOUNDINGS DO SHOW CIGS CLOSE TO IFR AROUND 12Z. HAVE SOMEWHAT BETTER
CONFIDENCE AT RFD WITH MET/RUC GUIDANCE HONING IN ON 09Z.
ONCE RIDGE AXIS PASSES THROUGH...WINDS WILL BEGIN TO INCREASE OUT OF
THE WEST...WSW. GUSTS WILL PICK UP DURING THE AFTERNOON HOURS
WEDNESDAY AHEAD OF AN APPROACHING COLD FRONT WITH MODEST MIXING
BRINGING DOWN LOW 20KT WINDS. PRECIP WILL STAY NORTH OF THE
CHICAGO/ROCKFORD TERMINALS. DO EXPECT CLOUD COVER TO ONCE AGAIN
INCREASE...BUT SHOULD STAY VFR.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 08Z...
* HIGH CONFIDENCE IN WIND FORECAST
* MODERATE TO HIGH CONFIDENCE IN VFR CIGS DROPPING TO MID-HIGH
MVFR...LOW CONFIDENCE IN FALLING BELOW 1.5 KFT
SHEA
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY...SLIGHT CHANCE OF SNOW OVERNIGHT. IFR/MVFR POSSIBLE.
FRIDAY...VFR.
SATURDAY...MVFR POSSIBLE.
SUNDAY...VFR.
MONDAY...VFR.
BMD
&&
.MARINE...
158 PM CST
A SURFACE RIDGE OF HIGH PRESSURE EXTENDING FROM THE PLAINS
NORTHEASTWARD ACROSS THE UPPER GREAT LAKES REGION WILL SLOWLY SAG
SOUTHWARD TONIGHT AS A STRONG AREA OF LOW PRESSURE MOVES INTO
THE HUDSON BAY. AS THIS SURFACE RIDGE MOVES ACROSS LAKE MICHIGAN
THERE WILL BE A PERIOD OF LIGHTER WINDS THIS EVENING. HOWEVER...THIS
WILL BE SHORT LIVED AS THE WINDS WILL BECOME WEST SOUTHWESTERLY AND
INCREASE TO NEAR 30 KT LATER TONIGHT ACROSS THE NORTHERN HALF OF THE
LAKE. THESE WINDS WILL CONTINUE LAKE-WIDE DURING THE DAY ON
WEDNESDAY AS A COLD FRONT MOVES SOUTH ACROSS THE LAKE. THERE COULD
BE A PERIOD OF LOW END GALES AS THE COLD AIR BEGINS TO PUSH ACROSS
THE LAKE WEDNESDAY NIGHT INTO THURSDAY. HOWEVER...WIDESPREAD 30 KT
WITH SOME GALE FORCE GUSTS APPEARS TO BE THE MOST LIKELY AT THIS
TIME.
WINDS ACROSS LAKE MICHIGAN LOOK TO REMAIN IN THE 15 TO 25 KT RANGE
INTO FRIDAY AS THE PRESSURE GRADIENT BETWEEN THE LOW ACROSS THE
HUDSON BAY AND HIGH PRESSURE ACROSS THE PLAINS REMAINS ELEVATED.
ANOTHER SURGE OF HIGHER WINDS...POTENTIALLY GALE FORCE...LOOKS TO
OCCUR ON SATURDAY AS ANOTHER AREA OF LOW PRESSURE TRACKS ACROSS
SOUTHERN CANADA.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1144 PM CST TUE DEC 6 2011
.DISCUSSION...
900 PM CST
AS ANTICIPATED...CLOUDS ARE MAKING IT EXTRA CHALLENGING WITH THE
TEMPERATURE FORECAST TONIGHT. THE CLEARING WAS SHORT-LIVED...WITH
CLOUDS BOTH EXPANDING AND ADVECTING BACK EAST WITHIN AND JUST ON
THE BACKSIDE OF THE LOW-LEVEL RIDGE. AN UPPER LEVEL TROUGH ALOFT
OVER THE AREA IS CONTINUING TO SHEAR OUT...WITH SUPPRESSION
APPARENTLY INCREASING LOOKING AT THE WATER VAPOR SATELLITE. THE
EVENING DVN AND ILX SOUNDINGS DEPICTED A FAIRLY DEEP 3000 FT LAYER
AT SATURATED OR NEAR-SATURATED...AND THERE ARE FEW SIGNS OF HOLES
EXISTING WITHIN THE CLOUD RIBBON. DESPITE THAT...THE BACK EDGE IS
PROGRESSING...LOCATED ABOUT 100 MILES WEST OF THE MISSISSIPPI
RIVER AROUND 9 PM. THE NAM AND RUC ANALYSIS OF 925-850MB MOISTURE
CAPTURE THIS WELL AND THE PROGRESSION OF THIS. THEIR DRYING
FORECAST COMES ACROSS NORTHERN IL FROM 3 AM THROUGH
DAYBREAK...COINCIDENT WITH THEIR DEPICTION OF HIGHER Q-VECTOR
DIVERGENCE /A PROXY FOR THE SUPPRESSION MENTIONED EARLIER/. THE
LAMP GUIDANCE HAS A VERY GOOD HANDLE ON THE STEADY TEMPERATURES
UNDER THE CLOUD COVER AND SHOW A LATE NIGHT DROP...ESPECIALLY IN
THE WESTERN FORECAST AREA. HAVE STEERED THIS AND THE RUC TREND
INTO THE FORECAST. OVERALL...MINIMUMS ARE SLIGHTLY WARMER FOR MOST
PLACES...A FEW DEGREES TOTAL FOR SOUTH AND EAST OF CHICAGO WHICH
SHOULD SEE THE CLOUDS ARRIVE SHORTLY AND LAST ALL THE WAY THROUGH
DAYBREAK.
MTF
PREVIOUS DISCUSSION...
417 PM CDT
SHORT TERM...THIS AFTERNOON THROUGH FRIDAY
MAIN CONCERN THIS PORTION OF THE FORECAST CENTERS ON LIGHT SNOW
CHANCES THURSDAY NIGHT INTO EARLY FRIDAY AND THEN BLAST OF ARCTIC
AIR FRIDAY INTO EARLY SATURDAY.
AFTERNOON WATER VAPOR IMAGERY SHOWS MID LEVEL TROUGHING ACROSS THE
REGION...WHILE AT THE SURFACE...HIGH PRESSURE STRETCHES FROM THE
WESTERN GREAT LAKES SOUTHWEST TO THE SOUTHERN PLAINS. ON VISIBLE
SATELLITE...EVER PRESENT STRATUS ACTUALLY HAS ERODED A BIT THIS
AFTERNOON FROM THE NORTH AS HIGH PRESSURE BUILDS IN. SUSPECT HOWEVER
THAT STRATUS WILL TEMPORARILY RETURN THIS EVENING AS FLOW BECOMES
NORTHERLY THEN WESTERLY. MODEL RH PROGS SHOW PLENTIFUL MOISTURE
BELOW 800 MB UNTIL LATER TONIGHT. THEN EXPECT THE REMAINING OVERCAST
TO ERODE FROM NORTHWEST. WITH CHILLY AIR MASS IN PLACE...TIMING OF
CLEARING TONIGHT WILL HAVE IMPACT ON LOW TEMPERATURES. THINK THAT
SKIES WILL CLEAR ENOUGH BY TOMORROW MORNING SO THAT...ALONG
WITH LIGHT WINDS...TEMPERATURES WILL BE ABLE TO PLUMMET TO THE UPPER
TEENS ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS. THE
REMAINDER OF THE AREA CAN EXPECT LOW TO MID 20S...WITH UPPER 20S IN
AND NEAR DOWNTOWN CHICAGO. WENT CLOSE TO MAV/MET GUIDANCE FOR LOWS
AND SLIGHTLY COLDER THAN PREVIOUS ISSUANCE.
WEDNESDAY WILL START OUT MOSTLY SUNNY...BUT CLOUDS MAY INCREASE JUST
A BIT IN THE AFTERNOON AS A COLD FRONT SWINGS THROUGH THE AREA
DURING THE AFTERNOON. LOW LEVELS WILL BE EXTREMELY DRY SO NO
PRECIPITATION IS FORECAST WITH THE FROPA. HIGHS WILL TOP OUT NEAR OR
JUST BELOW AVERAGE...LOW 30S OVER NORTH CENTRAL ILLINOIS AND MID 30S
FOR THE REMAINDER OF THE AREA. FROPA WILL SEND REINFORCING SHOT OF
COLDER AIR ACROSS REGION...AS TEMPERATURES COOL AT H85 WEDNESDAY
NIGHT TO ROUGHLY -8C. PRESSURE GRADIENT WILL REMAIN TIGHT ENOUGH TO
KEEP A WESTERLY BREEZE GOING...WITH LOWS LIKELY SIMILAR TO TONIGHT.
THURSDAY WILL BE A FEW DEGREES COOLER THAN WEDNESDAY...WITH CLOUDS
INCREASING FROM THE WEST AS A WAVE DEVELOPS WEST OF THE AREA ALONG
A TIGHT BAROCLINIC ZONE...WITH THE BULK OF ARCTIC AIR OVER THE
NORTHERN PLAINS AND UPPER MIDWEST NORTH OF OUR AREA. ON THURSDAY
NIGHT...DIGGING H5 TROUGH WILL SPAWN A WEAK SURFACE LOW WHICH WILL
TRACK ACROSS THE NORTHERN GREAT LAKES AND SEND AN ARCTIC
FRONTAL BOUNDARY TOWARD THE AREA. THE FRONTOGENETIC FORCED WAVE
ALONG THE ARCTIC FRONT WILL TRACK ALONG THE TIGHTEST THERMAL PACKING
TO NEAR OR OVER OUR AREA. MOST GUIDANCE...WITH THE EXCEPTION
OF THE NAM AND SREF HAVE COME INTO DECENT AGREEMENT ON A BAND OF
LIGHT QPF OVER ALL OF NORTHERN ILLINOIS AND NORTHWEST INDIANA ON
THURSDAY NIGHT INTO EARLY FRIDAY. TIME HEIGHTS AND SOUNDINGS
CONTINUE TO SHOW ADEQUATE SATURATION AND LIFT INTO THE FAVORABLE
DENDRITIC GROWTH AREA. THE RIGHT ENTRANCE REGION OF JET MAY PROVIDE
SOME ENHANCED LIFT. WITH COLD TEMPERATURES IN PLACE...EXPECTING 20:1
RATIO...WHICH WOULD RESULT IN THE FIRST LIGHT ACCUMULATING SNOWFALL
OF THE SEASON FOR MUCH OF THE AREA. AT THIS POINT...POTENTIAL EXISTS
FOR SOME LOCATIONS TO SEE IN EXCESS OF ONE INCH OF SNOWFALL. NOT
HIGH CONFIDENCE YET ON THIS FEATURE...SO DID STAY WITH CHANCE POPS
AS OPPOSED TO HIGHER POPS. IT MAY COME DOWN TO VERY CLOSE TO THE
EVENT UNTIL THE PART OF THE AREA WITH THE BEST FORCING FOR LIGHT
SNOW IS ASCERTAINED. ONCE WAVE QUICKLY SHIFTS EAST THROUGH THE
AREA...THE BIG STORY WILL BE SHARP COLD ADVECTION...WITH MINUS
TEEN TEMPERATURES AT H85 POISED TO POUR INTO AREA. WENT WITH BLENDED
MODEL GUIDANCE FOR LOWS EARLY FRIDAY MORNING...WHICH YIELDS UPPER
TEENS FAR NORTHERN ILLINOIS TO THE LOWER AND MIDDLE 20S FARTHER
SOUTH.
WITH STRONG COLD AIR ADVECTION ONGOING ON FRIDAY...IT WILL BE VERY
DIFFICULT TO RECOVER MUCH FROM THESE LOW TEMPERATURES. MODELS DIFFER
ON HOW COLD WE GET AT H85 AS THERMAL TROUGH REACHES AREA ON FRIDAY.
BUT THE GENERAL RANGE IS ABOUT -15C TO -20C. THUS WENT COLDER THAN
PREVIOUS FORECAST ISSUANCE BY SEVERAL DEGREES FOR FRIDAY...WITH LOW
20S FAR NORTH AND MIDDLE AND UPPER 20S ALONG AND SOUTH OF INTERSTATE
80. SOME LIGHT SNOW MAY LINGER OVER THE EASTERN PORTION OF THE
FORECAST AREA BEFORE SHIFTING EAST BY THE AFTERNOON.
LONG TERM...FRIDAY NIGHT THROUGH TUESDAY NIGHT
GUIDANCE HAS CONTINUED TO TREND COLDER WITH LOW TEMPERATURES
FRIDAY NIGHT...CAPTURED WELL BY A BLEND OF MODEL GUIDANCE AND
PREVIOUS FORECAST. ARCTIC HIGH WILL STRETCH ACROSS AREA...ALLOWING
FOR LIGHT WINDS AND STRONG RADIATIONAL COOLING OVERNIGHT. IF MINOR
SNOW COVER IS IN PLACE...FORECAST LOWS IN THE LOWER TO MIDDLE TEENS
FOR MUCH OF THE AREA OUTSIDE THE CHICAGO HEAT ISLAND MAY STILL END
UP BEING A FEW DEGREES TOO HIGH. SATURDAY WILL START OUT QUITE
COLD...BUT WARM ADVECTION ALOFT AND SOUTHWESTERLY FLOW AT THE
SURFACE WILL ALLOW FOR SOME RECOVERY TO THE UPPER 20S TO AROUND 30
DEGREES. FOR THE REMAINDER OF THE EXTENDED...THE AREA WILL REMAIN
INFLUENCED BY RIDGING OVER THE EASTERN CONUS...SO SOUTHWESTERLY
FLOW...DRY CONDITIONS...AND TEMPERATURES RETURNING TO SLIGHTLY ABOVE
NORMAL...OR AROUND 40 DEGREES...CAN BE EXPECTED. THERE MAY BE A COLD
FRONTAL PASSAGE DAY 6 OR DAY 7...BUT EVEN THAT MAY BE A DRY FROPA.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* VARIABLE CIGS THIS EVENING...MVFR RETURNING AND POTENTIAL FOR IFR.
* LIGHT WINDS THIS EVENING BECOMING WEST...WSW OVERNIGHT.
BMD
//DISCUSSION...UPDATED 06Z...
A RIDGE OF HIGH PRESSURE IS SINKING SOUTHEAST ACROSS THE FORECAST
AREA...WITH LIGHT AND VARIABLE WINDS ACROSS MUCH OF NORTHERN
ILLINOIS. WHILE WE DID CLEAR OUT BRIEFLY EARLIER THIS
EVENING...STRATUS HAS ADVANCED EASTWARD ALONG THE RIDGE AXIS AND
EXTENDS AS FAR WEST AS EASTERN IOWA LATE THIS EVENING. SURFACE OBS
SHOW MVFR DECK ADVANCING EAST ACROSS THE RIVER...WITH IFR CIGS
BECOMING MORE WIDESPREAD. DONT SEE ANY REASON WHY CLOUDS WOULD
SCATTER/CLEAR BEFORE DAYBREAK TOMORROW AS ANY SUBSIDENCE ACROSS THE
AREA WOULD ONLY ENHANCE THE INVERSION TO HOLD IN THE MOISTURE...THUS
BUMPED BACK TIMING OF CLEARING TIL MID MORNING AND LOWERED CIGS TO
015 LATE TONIGHT. CANT RULE OUT IFR CONDITIONS REACHING THE CHICAGO
TERMINALS...BUT WITH GUIDANCE STILL NOT LOCKING ONTO THE LOW CIGS
DONT HAVE MUCH FEEL FOR HOW LOW CIGS WILL DROP OR WHEN...THOUGH RUC
SOUNDINGS DO SHOW CIGS CLOSE TO IFR AROUND 12Z. HAVE SOMEWHAT BETTER
CONFIDENCE AT RFD WITH MET/RUC GUIDANCE HONING IN ON 09Z.
ONCE RIDGE AXIS PASSES THROUGH...WINDS WILL BEGIN TO INCREASE OUT OF
THE WEST...WSW. GUSTS WILL PICK UP DURING THE AFTERNOON HOURS
WEDNESDAY AHEAD OF AN APPROACHING COLD FRONT WITH MODEST MIXING
BRINGING DOWN LOW 20KT WINDS. PRECIP WILL STAY NORTH OF THE
CHICAGO/ROCKFORD TERMINALS. DO EXPECT CLOUD COVER TO ONCE AGAIN
INCREASE...BUT SHOULD STAY VFR.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM TO HIGH CONFIDENCE IN WIND FORECAST.
* MEDIUM TO HIGH CONFIDENCE IN MVFR CONDITIONS...LOW CONFIDENCE
IN IFR.
BMD
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY...SLIGHT CHANCE OF SNOW OVERNIGHT. IFR/MVFR POSSIBLE.
FRIDAY...VFR.
SATURDAY...MVFR POSSIBLE.
SUNDAY...VFR.
MONDAY...VFR.
BMD
&&
.MARINE...
158 PM CST
A SURFACE RIDGE OF HIGH PRESSURE EXTENDING FROM THE PLAINS
NORTHEASTWARD ACROSS THE UPPER GREAT LAKES REGION WILL SLOWLY SAG
SOUTHWARD TONIGHT AS A STRONG AREA OF LOW PRESSURE MOVES INTO
THE HUDSON BAY. AS THIS SURFACE RIDGE MOVES ACROSS LAKE MICHIGAN
THERE WILL BE A PERIOD OF LIGHTER WINDS THIS EVENING. HOWEVER...THIS
WILL BE SHORT LIVED AS THE WINDS WILL BECOME WEST SOUTHWESTERLY AND
INCREASE TO NEAR 30 KT LATER TONIGHT ACROSS THE NORTHERN HALF OF THE
LAKE. THESE WINDS WILL CONTINUE LAKE-WIDE DURING THE DAY ON
WEDNESDAY AS A COLD FRONT MOVES SOUTH ACROSS THE LAKE. THERE COULD
BE A PERIOD OF LOW END GALES AS THE COLD AIR BEGINS TO PUSH ACROSS
THE LAKE WEDNESDAY NIGHT INTO THURSDAY. HOWEVER...WIDESPREAD 30 KT
WITH SOME GALE FORCE GUSTS APPEARS TO BE THE MOST LIKELY AT THIS
TIME.
WINDS ACROSS LAKE MICHIGAN LOOK TO REMAIN IN THE 15 TO 25 KT RANGE
INTO FRIDAY AS THE PRESSURE GRADIENT BETWEEN THE LOW ACROSS THE
HUDSON BAY AND HIGH PRESSURE ACROSS THE PLAINS REMAINS ELEVATED.
ANOTHER SURGE OF HIGHER WINDS...POTENTIALLY GALE FORCE...LOOKS TO
OCCUR ON SATURDAY AS ANOTHER AREA OF LOW PRESSURE TRACKS ACROSS
SOUTHERN CANADA.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1007 PM CST TUE DEC 6 2011
.DISCUSSION...
900 PM CST
AS ANTICIPATED...CLOUDS ARE MAKING IT EXTRA CHALLENGING WITH THE
TEMPERATURE FORECAST TONIGHT. THE CLEARING WAS SHORT-LIVED...WITH
CLOUDS BOTH EXPANDING AND ADVECTING BACK EAST WITHIN AND JUST ON
THE BACKSIDE OF THE LOW-LEVEL RIDGE. AN UPPER LEVEL TROUGH ALOFT
OVER THE AREA IS CONTINUING TO SHEAR OUT...WITH SUPPRESSION
APPARENTLY INCREASING LOOKING AT THE WATER VAPOR SATELLITE. THE
EVENING DVN AND ILX SOUNDINGS DEPICTED A FAIRLY DEEP 3000 FT LAYER
AT SATURATED OR NEAR-SATURATED...AND THERE ARE FEW SIGNS OF HOLES
EXISTING WITHIN THE CLOUD RIBBON. DESPITE THAT...THE BACK EDGE IS
PROGRESSING...LOCATED ABOUT 100 MILES WEST OF THE MISSISSIPPI
RIVER AROUND 9 PM. THE NAM AND RUC ANALYSES OF 925-850MB MOISTURE
CAPTURE THIS WELL AND THE PROGRESSION OF THIS. THEIR DRYING
FORECAST COMES ACROSS NORTHERN IL FROM 3 AM THROUGH
DAYBREAK...COINCIDENT WITH THEIR DEPICTION OF HIGHER Q-VECTOR
DIVERGENCE /A PROXY FOR THE SUPPRESSION MENTIONED EARLIER/. THE
LAMP GUIDANCE HAS A VERY GOOD HANDLE ON THE STEADY TEMPERATURES
UNDER THE CLOUD COVER AND SHOW A LATE NIGHT DROP...ESPECIALLY IN
THE WESTERN FORECAST AREA. HAVE STEERED THIS AND THE RUC TREND
INTO THE FORECAST. OVERALL...MINIMUMS ARE SLIGHTLY WARMER FOR MOST
PLACES...A FEW DEGREES TOTAL FOR SOUTH AND EAST OF CHICAGO WHICH
SHOULD SEE THE CLOUDS ARRIVE SHORTLY AND LAST ALL THE WAY THROUGH
DAYBREAK.
MTF
PREVIOUS DISCUSSION...
417 PM CDT
SHORT TERM...THIS AFTERNOON THROUGH FRIDAY
MAIN CONCERN THIS PORTION OF THE FORECAST CENTERS ON LIGHT SNOW
CHANCES THURSDAY NIGHT INTO EARLY FRIDAY AND THEN BLAST OF ARCTIC
AIR FRIDAY INTO EARLY SATURDAY.
AFTERNOON WATER VAPOR IMAGERY SHOWS MID LEVEL TROUGHING ACROSS THE
REGION...WHILE AT THE SURFACE...HIGH PRESSURE STRETCHES FROM THE
WESTERN GREAT LAKES SOUTHWEST TO THE SOUTHERN PLAINS. ON VISIBLE
SATELLITE...EVER PRESENT STRATUS ACTUALLY HAS ERODED A BIT THIS
AFTERNOON FROM THE NORTH AS HIGH PRESSURE BUILDS IN. SUSPECT HOWEVER
THAT STRATUS WILL TEMPORARILY RETURN THIS EVENING AS FLOW BECOMES
NORTHERLY THEN WESTERLY. MODEL RH PROGS SHOW PLENTIFUL MOISTURE
BELOW 800 MB UNTIL LATER TONIGHT. THEN EXPECT THE REMAINING OVERCAST
TO ERODE FROM NORTHWEST. WITH CHILLY AIR MASS IN PLACE...TIMING OF
CLEARING TONIGHT WILL HAVE IMPACT ON LOW TEMPERATURES. THINK THAT
SKIES WILL CLEAR ENOUGH BY TOMORROW MORNING SO THAT...ALONG
WITH LIGHT WINDS...TEMPERATURES WILL BE ABLE TO PLUMMET TO THE UPPER
TEENS ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS. THE
REMAINDER OF THE AREA CAN EXPECT LOW TO MID 20S...WITH UPPER 20S IN
AND NEAR DOWNTOWN CHICAGO. WENT CLOSE TO MAV/MET GUIDANCE FOR LOWS
AND SLIGHTLY COLDER THAN PREVIOUS ISSUANCE.
WEDNESDAY WILL START OUT MOSTLY SUNNY...BUT CLOUDS MAY INCREASE JUST
A BIT IN THE AFTERNOON AS A COLD FRONT SWINGS THROUGH THE AREA
DURING THE AFTERNOON. LOW LEVELS WILL BE EXTREMELY DRY SO NO
PRECIPITATION IS FORECAST WITH THE FROPA. HIGHS WILL TOP OUT NEAR OR
JUST BELOW AVERAGE...LOW 30S OVER NORTH CENTRAL ILLINOIS AND MID 30S
FOR THE REMAINDER OF THE AREA. FROPA WILL SEND REINFORCING SHOT OF
COLDER AIR ACROSS REGION...AS TEMPERATURES COOL AT H85 WEDNESDAY
NIGHT TO ROUGHLY -8C. PRESSURE GRADIENT WILL REMAIN TIGHT ENOUGH TO
KEEP A WESTERLY BREEZE GOING...WITH LOWS LIKELY SIMILAR TO TONIGHT.
THURSDAY WILL BE A FEW DEGREES COOLER THAN WEDNESDAY...WITH CLOUDS
INCREASING FROM THE WEST AS A WAVE DEVELOPS WEST OF THE AREA ALONG
A TIGHT BAROCLINIC ZONE...WITH THE BULK OF ARCTIC AIR OVER THE
NORTHERN PLAINS AND UPPER MIDWEST NORTH OF OUR AREA. ON THURSDAY
NIGHT...DIGGING H5 TROUGH WILL SPAWN A WEAK SURFACE LOW WHICH WILL
TRACK ACROSS THE NORTHERN GREAT LAKES AND SEND AN ARCTIC
FRONTAL BOUNDARY TOWARD THE AREA. THE FRONTOGENETIC FORCED WAVE
ALONG THE ARCTIC FRONT WILL TRACK ALONG THE TIGHTEST THERMAL PACKING
TO NEAR OR OVER OUR AREA. MOST GUIDANCE...WITH THE EXCEPTION
OF THE NAM AND SREF HAVE COME INTO DECENT AGREEMENT ON A BAND OF
LIGHT QPF OVER ALL OF NORTHERN ILLINOIS AND NORTHWEST INDIANA ON
THURSDAY NIGHT INTO EARLY FRIDAY. TIME HEIGHTS AND SOUNDINGS
CONTINUE TO SHOW ADEQUATE SATURATION AND LIFT INTO THE FAVORABLE
DENDRITIC GROWTH AREA. THE RIGHT ENTRANCE REGION OF JET MAY PROVIDE
SOME ENHANCED LIFT. WITH COLD TEMPERATURES IN PLACE...EXPECTING 20:1
RATIO...WHICH WOULD RESULT IN THE FIRST LIGHT ACCUMULATING SNOWFALL
OF THE SEASON FOR MUCH OF THE AREA. AT THIS POINT...POTENTIAL EXISTS
FOR SOME LOCATIONS TO SEE IN EXCESS OF ONE INCH OF SNOWFALL. NOT
HIGH CONFIDENCE YET ON THIS FEATURE...SO DID STAY WITH CHANCE POPS
AS OPPOSED TO HIGHER POPS. IT MAY COME DOWN TO VERY CLOSE TO THE
EVENT UNTIL THE PART OF THE AREA WITH THE BEST FORCING FOR LIGHT
SNOW IS ASCERTAINED. ONCE WAVE QUICKLY SHIFTS EAST THROUGH THE
AREA...THE BIG STORY WILL BE SHARP COLD ADVECTION...WITH MINUS
TEEN TEMPERATURES AT H85 POISED TO POUR INTO AREA. WENT WITH BLENDED
MODEL GUIDANCE FOR LOWS EARLY FRIDAY MORNING...WHICH YIELDS UPPER
TEENS FAR NORTHERN ILLINOIS TO THE LOWER AND MIDDLE 20S FARTHER
SOUTH.
WITH STRONG COLD AIR ADVECTION ONGOING ON FRIDAY...IT WILL BE VERY
DIFFICULT TO RECOVER MUCH FROM THESE LOW TEMPERATURES. MODELS DIFFER
ON HOW COLD WE GET AT H85 AS THERMAL TROUGH REACHES AREA ON FRIDAY.
BUT THE GENERAL RANGE IS ABOUT -15C TO -20C. THUS WENT COLDER THAN
PREVIOUS FORECAST ISSUANCE BY SEVERAL DEGREES FOR FRIDAY...WITH LOW
20S FAR NORTH AND MIDDLE AND UPPER 20S ALONG AND SOUTH OF INTERSTATE
80. SOME LIGHT SNOW MAY LINGER OVER THE EASTERN PORTION OF THE
FORECAST AREA BEFORE SHIFTING EAST BY THE AFTERNOON.
LONG TERM...FRIDAY NIGHT THROUGH TUESDAY NIGHT
GUIDANCE HAS CONTINUED TO TREND COLDER WITH LOW TEMPERATURES
FRIDAY NIGHT...CAPTURED WELL BY A BLEND OF MODEL GUIDANCE AND
PREVIOUS FORECAST. ARCTIC HIGH WILL STRETCH ACROSS AREA...ALLOWING
FOR LIGHT WINDS AND STRONG RADIATIONAL COOLING OVERNIGHT. IF MINOR
SNOW COVER IS IN PLACE...FORECAST LOWS IN THE LOWER TO MIDDLE TEENS
FOR MUCH OF THE AREA OUTSIDE THE CHICAGO HEAT ISLAND MAY STILL END
UP BEING A FEW DEGREES TOO HIGH. SATURDAY WILL START OUT QUITE
COLD...BUT WARM ADVECTION ALOFT AND SOUTHWESTERLY FLOW AT THE
SURFACE WILL ALLOW FOR SOME RECOVERY TO THE UPPER 20S TO AROUND 30
DEGREES. FOR THE REMAINDER OF THE EXTENDED...THE AREA WILL REMAIN
INFLUENCED BY RIDGING OVER THE EASTERN CONUS...SO SOUTHWESTERLY
FLOW...DRY CONDITIONS...AND TEMPERATURES RETURNING TO SLIGHTLY ABOVE
NORMAL...OR AROUND 40 DEGREES...CAN BE EXPECTED. THERE MAY BE A COLD
FRONTAL PASSAGE DAY 6 OR DAY 7...BUT EVEN THAT MAY BE A DRY FROPA.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 04Z...
* VARIABLE CIGS THIS EVENING...MVFR RETURNING LATE THIS
EVENING...AND POTENTIAL FOR IFR.
* LIGHT WINDS BECOMING WEST...WSW OVERNIGHT. BMD
//DISCUSSION...UPDATED 00Z...
MAIN FORECAST CONCERNS WILL BE DEALING WITH VARIABLE CIGS AND
BACKING WINDS AS RIDGE AXIS SLIDES ACROSS THE REGION. SKIES HAVE
CLEARED OUT OVER MOST OF NORTH CENTRAL AND NORTHEASTERN ILLINOIS
THIS EVENING...HOWEVER NARROW BAND OF STRATUS UNDER THE RIDGE
AXIS WITH MVFR AND OCCASIONAL IFR CIGS SPANNING ACROSS
NORTHWESTERN ILLINOIS AND EASTERN IOWA. THIS MOISTURE WILL MOVE
EAST AHEAD OF THE RIDGE...WITH POTENTIALLY MVFR CIGS RETURNING
OVERNIGHT. MOS GUIDANCE DOES NOT HANDLE THIS MOISTURE
WELL...HOWEVER NAM/RUC 925MB RH FIELDS DO INDICATE LOW LEVEL
MOISTURE RETURNING AFTER MIDNIGHT LOCAL TONIGHT TO THE CHICAGO
AREA TERMINALS. LOW LEVEL MOISTURE IS EXPECTED TO PUSH OUT OF THE
AREA MID TO LATE MORNING WITH ADDITIONAL HIGH AND MID CLOUDS
MOVING IN FROM THE NORTH ALONG THE TAIL END OF A COLD FRONT. NO
PRECIP IS EXPECTED...HOWEVER WINDS ARE EXPECTED TO TURN BACK TO
THE WNW BY LATE WEDNESDAY AFTERNOON/EARLY EVENING. BMD
//ORD AND MDW CONFIDENCE...UPDATED 04Z...
* MEDIUM TO HIGH CONFIDENCE IN WIND FORECAST.
* MEDIUM CONFIDENCE IN DETAILS OF CIG FORECAST. BMD
//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...
THURSDAY...SLIGHT CHANCE OF SNOW OVERNIGHT. IFR/MVFR POSSIBLE.
FRIDAY...VFR.
SATURDAY...MVFR POSSIBLE.
SUNDAY...VFR.
MONDAY...VFR.
BMD
&&
.MARINE...
158 PM CST
A SURFACE RIDGE OF HIGH PRESSURE EXTENDING FROM THE PLAINS
NORTHEASTWARD ACROSS THE UPPER GREAT LAKES REGION WILL SLOWLY SAG
SOUTHWARD TONIGHT AS A STRONG AREA OF LOW PRESSURE MOVES INTO
THE HUDSON BAY. AS THIS SURFACE RIDGE MOVES ACROSS LAKE MICHIGAN
THERE WILL BE A PERIOD OF LIGHTER WINDS THIS EVENING. HOWEVER...THIS
WILL BE SHORT LIVED AS THE WINDS WILL BECOME WEST SOUTHWESTERLY AND
INCREASE TO NEAR 30 KT LATER TONIGHT ACROSS THE NORTHERN HALF OF THE
LAKE. THESE WINDS WILL CONTINUE LAKE-WIDE DURING THE DAY ON
WEDNESDAY AS A COLD FRONT MOVES SOUTH ACROSS THE LAKE. THERE COULD
BE A PERIOD OF LOW END GALES AS THE COLD AIR BEGINS TO PUSH ACROSS
THE LAKE WEDNESDAY NIGHT INTO THURSDAY. HOWEVER...WIDESPREAD 30 KT
WITH SOME GALE FORCE GUSTS APPEARS TO BE THE MOST LIKELY AT THIS
TIME.
WINDS ACROSS LAKE MICHIGAN LOOK TO REMAIN IN THE 15 TO 25 KT RANGE
INTO FRIDAY AS THE PRESSURE GRADIENT BETWEEN THE LOW ACROSS THE
HUDSON BAY AND HIGH PRESSURE ACROSS THE PLAINS REMAINS ELEVATED.
ANOTHER SURGE OF HIGHER WINDS...POTENTIALLY GALE FORCE...LOOKS TO
OCCUR ON SATURDAY AS ANOTHER AREA OF LOW PRESSURE TRACKS ACROSS
SOUTHERN CANADA.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED FOR 06Z TAFS
NWS MARQUETTE MI
1123 PM EST TUE DEC 6 2011
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED A SHEARED MID/UPPER LEVEL
TROUGH FROM NRN ONTARIO THROUGH NW WI AND IA INTO THE CNTRL PLAINS.
AN UPSTREAM SHORTWAVE TROUGH WAS MOVING THROUGH CNTRL MANITOBA. AT
THE SFC...SW FLOW WAS INCREASING OVER WRN LAKE SUPERIOR AND W UPPER
MI BTWN A DEPARTING RIDGE FROM QUEBEC INTO EAST UPPER MI AND A
TROUGH OVER MANITOBA. ALTHOUGH THE BACKING WINDS HAVE PUSHED THE
LAKE CLOUDS OFFSHORE OVER THE CNTRL AND WEST CWA...LOWER LEVEL
MOISTURE OVER WRN WI WAS STREAMING BACK INTO THE WEST...PER VIS
LOOP. MID LEVEL CLOUDS WERE ADVANCING THROUGH NW ONTARIO AND NRN MN
ASSOCIATED WITH WAA/295K ISENTROPIC LIFT AHEAD OF THE TROUGH.
&&
.SHORT TERM...TONIGHT AND WEDNESDAY
MAIN FCST CONCERN IS LES POTENTIAL WITH THE FRONT/TROUGH MOVING
THROUGH THE AREA.
SATELLITE TRENDS AND NAM/RUC 925-900 MB RH FCST SUGGESTS THAT THE
LOWER CLOUDS WILL CONTINUE TO SPREAD TO THE EAST THIS EVENING AND
THEN MOVE OUT OVERNIGHT AS WINDS BEGIN TO VEER MORE TO THE WNW.
MODERATE MID LEVEL QVECTOR CONV ASSOCIATED WITH THE TROUGH MOVING
INTO THE AREA WED MORNING WILL BRING AN INCREASE IN 850-700 MB
MOISTURE. WITH WINDS VEERING WRLY AND 850 MB TEMPS TO AROUND
-11C...CONDITIONS WILL BECOME MORE FAVORABLE FOR LES INTO THE
KEWEENAW LATE TONIGHT INTO WED MORNING. CAA DROPS 850 MB TEMPS TO
AROUND -14C DURING THE AFTERNOON...BUT THE DEEPER MOISTURE IS
EXPECTED TO DEPART. SINCE THE PERIOD WITH THE COMBINATION OF LOW
LEVEL CONV AND 850-700 MB MOISTURE IS BRIEF...ANY LES
ACCUMULATIONS ARE EXPECTED TO BE LIGHT...GENERALLY AN INCH OR LESS.
SCT -SHSN WILL ALSO AFFECT LOCATIONS E OF MUNISING DURING THE
AFTERNOON BUT AGAIN ACCUMULATIONS SHOULD BE LIGHT.
.LONG TERM /WED NIGHT THROUGH NEXT TUESDAY/...
COLD FRONT THAT WILL START THE COOLING TREND WILL BE EAST OF THE
AREA AT THE START OF THE PERIOD...WHICH WILL PRODUCED A PROLONGED
LAKE EFFECT SNOW PERIOD FOR PORTIONS OF UPPER MICHIGAN.
EXPECT SFC LOW TO BE STATIONED OVER HUDSON BAY THROUGH SAT...WHILE A
SFC HIGH SHIFTS FROM THE NRN PLAINS ON THURS TO THE OHIO RIVER
VALLEY BY FRI NIGHT. THIS WILL LEAD TO WINDS OUT OF A WNW DIRECTION
ON WED NIGHT INTO THURS...THEN BACKING TO THE W FOR THURS NIGHT INTO
FRI NIGHT. THIS A LITTLE MORE WESTERLY THAN SHOWN YESTERDAY AND WILL
LIKELY FOCUS PCPN OVER THE ERN CWA TO BE FROM GRAND MARAIS
EASTWARD...RIGHT ALONG THE SHORELINE. THINK LAND BREEZES WILL HELP
FOCUS A DOMINATE BAND EITHER RIGHT ALONG THE SHORELINE OR JUST
OFFSHORE AT TIMES DURING THE PERIOD. OVER THE WEST...FAVORABLE
LOCATIONS WILL BE FROM ROCKLAND THROUGH COPPER HARBOR...ESPECIALLY
OVER THE HIGHER TERRAIN.
EXPECT LES TO BE ONGOING AT THE START OF THE PERIOD...BUT WILL
REALLY BEGIN TO RAMP UP OVERNIGHT WED INTO THURS MORNING...AS
SHORTWAVE AND SECONDARY SFC TROUGH SWEEP ACROSS THE AREA. THIS WILL
INCREASE MID LVL MOISTURE AND START A DOWNWARD TREND IN H850 TEMPS
FROM -14C /DELTA-T OF 19/ TO -20C OVER THE W AND -18C OVER THE E.
THESE VALUES DON/T LOOK AS COLD AS YESTERDAY FOR THE THURS/FRI TIME
FRAME...WHICH WILL BE MORE FAVORABLE FOR THE LES POTENTIAL...AS THE
DGZ WILL BE RIGHT IN THE BEST OMEGA. IN ADDITION...MODELS SHOWING A
MORE MOIST LLVL...WITH LESS SUB CLOUD LAYER DRY AIR. THIS ALLOWS THE
BEST LK INDUCED FORCING TO BE LOCATED DIRECTLY IN OR THE TOP HALF OF
THE DGZ AND AID FOR FASTER ACCUMULATION. THUS...HAVE BUMPED UP SLR
UP SLIGHTLY INTO THE LOW/MID 20S...ALTHOUGH NOT QUITE AS HIGH AS
SEEN ON SOME OF THE CARIBOU SLR VALUES.
MIGHT BE A LITTLE LULL IN LES OVER THE WEST ON THURS AFTN...AS DRIER
AIR ABOVE H800 MOVES THROUGH AND LOWERS THE INVERSION HEIGHTS. THIS
WILL BE SHORT LIVED AS NEXT WAVE OF DEEPER MOISTURE MOVES IN AND
INVERSION HEIGHTS RISE ON THURS NIGHT WITH THE UPPER TROUGH MOVING
OVERHEAD. EVEN WITH THIS LULL...THERE WILL STILL BE GUSTY WINDS THAT
WILL CREATE BLOWING/DRIFTING SNOW ALONG THE LK SUPERIOR SHORELINE
WITH THE FAIRLY FLUFFY SNOW THAT WILL HAVE FALLEN WED NIGHT INTO
THURS MORNING.
FRI DEEPER MOISTURE STARTS TO DEPART THE WEST DURING THE
DAY...STARTING TO DIMINISH LES INSTENSITY...BUT WILL STILL BE
ONGOING THROUGH FRI NIGHT. WITH WINDS SHIFTING MORE OUT OF THE
WSW...EXPECT BEST BANDS TO BE OVER THE KEWEENAW AND OFFSHORE OVER
THE E /ALTHOUGH A WEAK TROUGH COULD SLIDE THE BAND BACK ONSHORE FRI
NIGHT/.
AS FOR SNOWFALL AMOUNTS...LES PARAMETER EXCEEDS 2 FOR MUCH OF THE
PERIOD...WHICH ALONG WITH LK INDUCED CAPE VALUES EXCEEDING 700 J/KG
AND EQL/S IN THE 9-12KFT RANGE...THE POTENTIAL IS THERE FOR HEAVY
SNOWFALL ACCUMULATIONS. CURRENT FCST FROM 6Z THURS TO 6Z SAT HAS
12-20 INCHES OVER THE HIGHER TERRAIN FROM ROCKLAND TO CALUMET AND
SIMILAR TOTALS RIGHT ALONG THE LK SUPERIOR SHORELINE E OF GRAND
MARAIS. WILL LIKELY SEE A COUPLE PERIODS WHERE OUR 8IN/12HR WARN
CRITERIA WILL BE REACHED OVER THE WEST...SO HAVE PUT OUT A LES WATCH
FOR ONTONAGON THROUGH KEWEENAW COUNTIES. HAVE LIMITED CONFIDENCE IN
THE EAST WITH BAND LOCATION DUE TO THE LITTLE MORE WRLY WINDS AND
SOME LIKELY WANDERING OF THE BAND ON/OFF SHORE THROUGH THE
PERIOD...SO HELD OFF ON A WATCH FOR TIME BEING.
DAYS 4 THROUGH 7 /FRI NIGHT THROUGH NEXT TUESDAY/...
EXPECT LES TO COME TO AN END ON SAT...AS A CLIPPER SYSTEM DROPS
THROUGH SOUTHERN ONTARIO AND SHIFTS WINDS TO THE SW AND PRODUCES WAA
ALOFT. FINE DETAILS BECOME A LITTLE MORE MUDDLED FOR SUN THROUGH
TUES...AS NO MAJOR DISTURBANCES OR FEATURES AFFECT THE REGION. THIS
LEAVES THE AREA UNDER ZONAL FLOW ALOFT FOR SUN...AHEAD OF A
SHORTWAVE MOVING ACROSS THE AREA MON INTO MON NIGHT. WITH H850 TEMPS
AROUND -1C ON SUN...EXPECT TEMPS TO BE SLIGHTLY ABOVE NORMAL WITH
HIGHS IN THE LOWER 30S. SUN NIGHT INTO MON NIGHT SHOULD SEE A SFC
TROUGH NEAR THE UPPER GREAT LKS REGION...BUT WITH HOW WEAK IT
APPEARS TO BE WITH THE ZONAL FLOW...HAVE LIMITED CONFIDENCE ON PCPN.
THUS...WILL GO WITH A MOSTLY CLOUDY PERIOD...ALTHOUGH THE BEST
CHANCE FOR PCPN WILL BE MON INTO MON NIGHT. THESE CLOUDS WILL KEEP
OVERNIGHT LOWS FROM BEING TOO COLD AND KEEP TEMPS NEAR NORMAL FOR
MON INTO TUES.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/
SW GRADIENT WINDS AHEAD OF APPROACHING COLD FRONT WILL SUPPORT LLWS
AT ALL TAF SITES OVERNIGHT. WINDS VEERING WRLY IN THE MORNING BEHIND
THE FRONT SHOULD BRING MVFR CIGS BACK INTO KIWD AND KCMX EARLY THIS
MORNING. FAVORABLE WRLY FLOW AT KCMX MAY RESULT IN WIND GUSTS
AOA 30 KTS AS WELL AS POSSIBLE LAKE EFFECT SNOW SHOWERS. DRIER AIR
WILL MOVE INTO KIWD WED MORNING AND KEEP LAKE EFFECT CLOUDS NORTH OF
THE SITE. KSAW WILL STAY VFR THROUGH THE PERIOD.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
SW WINDS ARE EXPECTED TO INCREASE TO GALE FORCE TONIGHT INTO EARLY
WED...MAINLY OVER WESTERN AND NCNTRL LAKE SUPERIOR AHEAD OF A TROUGH
MOVING TOWARD THE REGION. AS WINDS VEER NW BEHIND THE TROUGH...WINDS
ARE EXPECTED TO DIMINISH INTO THE 20-30 KT RANGE. A WINTRY PATTERN
OF W-NW WINDS WILL THEN PERSIST THRU LATE WEEK WITH LAKE EFFECT SNOW
SHOWERS. GIVEN ARCTIC AIR PASSING OVER THE LAKE AND EFFICIENT
MIXING...EXPECT WINDS CONSISTENTLY 20-30 KT WITH ANOTHER PERIOD OF
GALES POSSIBLE AGAIN LATE WED NIGHT AND THURSDAY. COMBINATION OF
ARCTIC AIR AND STRONG WIND SHOULD RESULT IN FREEZING SPRAY WED NIGHT
INTO FRIDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WATCH FROM LATE WEDNESDAY NIGHT THROUGH LATE
FRIDAY NIGHT FOR MIZ001>003.
LAKE SUPERIOR...
GALE WARNING UNTIL 10 AM EST WEDNESDAY FOR LSZ266.
GALE WARNING UNTIL 7 AM EST /6 AM CST/ WEDNESDAY FOR LSZ162.
GALE WARNING UNTIL 10 AM EST WEDNESDAY FOR LSZ263-264.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...JLB
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...07
MARINE...JLB
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
122 AM EST WED DEC 7 2011
.SYNOPSIS...
DRIZZLE AND PATCHY FOG WILL BE OVER THE REGION OVERNIGHT, AS A
STORM SYSTEM SLOWLY PULLS EASTWARD. A STRONGER STORM WILL DEVELOP
IN THE MID ATLANTIC REGION WEDNESDAY AFTERNOON THEN TRACK
NORTHEAST ALONG THE COAST WEDNESDAY NIGHT. A RAIN AND SNOW MIX IS
LIKELY INITIALLY WEDNESDAY EVENING, THEN AS COLDER AIR GETS DRAWN
INTO THE SYSTEM A PERIOD OF SNOW IS LIKELY, WITH SEVERAL INCHES OF
SNOW POSSIBLE FOR THE WESTERN CATSKILLS AND POCONOS.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
THE FRONT IS ALONG OUR EXTREME EASTERN BORDER AT THIS HOUR.
TEMPERATURES REMAIN IN THE MID 50S OVER SULLIVAN COUNTY NY, WHILE
BROOME AND CHENANGO IS NOW IN THE UPPER 30S.
PATCHY DENSE FOG IS BEING OBSERVED, MAINLY ALONG THE HIGHER
ELEVATIONS. THE SURFACE OBS SHOW THAT THE DENSE FOG IS NOT
WIDESPREAD, SO WE WILL HOLD OFF ON A DENSE FOG ADVISORY.
SPOTTY DRIZZLE CONTINUES BEHIND THE FRONT. TEMPERATURES ARE
HOLDING IN THE MIDDLE TO UPPER 30S ACROSS OUR WESTERN AND CENTRAL
ZONES. LATEST RUC13 AND HRRR GUIDANCE SUGGESTS TEMPERATURES WILL
BARELY FALL OVERNIGHT, SO WE ARE NOT ANTICIPATING FREEZING
DRIZZLE. A FEW ISOLATED REPORTS ARE POSSIBLE...BUT THAT WOULD NOT
BE IN THE NEXT FEW HOURS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY/...
WEDNESDAY/WEDNESDAY NIGHT...UPPER LEVEL WAVE SHARPENS IN THE TN
VALLEY THEN MOVES INTO THE MID ATLANTIC REGION BY WEDNESDAY
EVENING. SFC LOW DEVELOPS IN RESPONSE TO THIS UPPER LEVEL WAVE
AND DEEPENS AS IT MOVES INTO THE MID ATLANTIC REGION BY WEDNESDAY
AFTERNOON. THIS FEATURE THEN TRACK NORTHEAST OFF THE SOUTHERN NJ
COAST AND INTO COASTAL NEW ENGLAND BY 12Z THURSDAY. MODEL TRENDS
HAVE BEEN TO TRACK SYSTEM FURTHER NORTH AND WEST LEADING TO MORE
PRECIP FOR FORECAST AREA. SNOW FORECAST VERY DIFFICULT WITH THIS
SYSTEM DUE TO FAST MOTION AND INITIALLY PRECIP WILL BE IN THE FORM
OF RAIN/SNOW THEN CHANGE TO ALL SNOW AS COLD AIR DEEPENS BEHIND
WAVE. FOR NOW IT LOOKS LIKE AND ADVISORY SNOWFALL FOR THE HIGHER
TERRAIN OF THE WESTERN CATSKILLS AND POCONOS WITH 3-5 INCHES
LIKELY. IF THE CONSENSUS TRACK CHANGES IT WILL HAVE A BIG IMPACT
ON TOTAL SNOW ACCUMS.
THURSDAY THROUGH FRIDAY...BEHIND THIS WAVE COLDER AIR WILL SPREAD
ACROSS CENTRAL NEW YORK WITH CONDITIONS MARGINAL FAVORABLE FOR
SOME LAKE EFFECT SNOW THURSDAY AFTERNOON THROUGH THURSDAY NIGHT.
WITH W/SW FLOW ACTIVITY WILL RESIDE MAINLY OVER NRN ONEIDA COUNTY
AND PARTS OF STEUBEN COUNTY AND THE FINGER LAKES REGION FROM LAKE ERIE.
ON FRIDAY THE NEXT UPPER LEVEL TROF WILL APPROACH THE REGION FROM
THE UPPER GREAT LAKES. WILL CONTINUE WITH CHC POPS FOR ALL BUT FAR
SE FA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
UPDATED AT 120 AM...GIVEN SHORT TERM CONCERNS WE HAVE MADE LTL CHG
TO THE MED RNG FCST...WHICH IS BASICALLY INDICATING QUIET WX.
PREV BLO...
XNTDD PD BEGINS WITH A NW FLOW OF COLD AIR AND PSBL LE SNOW SHWRS
FOR MUCH OF THE AREA. THIS CONTS INTO SAT AS THE BASE OF THE UPR
TROF MVES THRU. GRADUAL WRM UP WITH DRIER AIR BEGINS LATE
SUN...BUT RDG IS FLAT AND WSW FLOW IS SLOW TO BRING HIER TEMPS TO
THE AREA. SOME LE MAY LINGER ACROSS THE NRN ZONES INTO SUN. WRMR
ON MON WITH THE SFC HI OFF TO THE EAST AND CONTD DRY WSW FLOW. H8
TEMPS CLIMB ABOVE 0C. COLD FNT ON TUES WILL BRING BACK THE PSBLTY
OF SOME LGT RAIN OR SNOW SHWRS...AND SOME WEAK LAKE ENHANCEMENT.
&&
.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
WDSPRD IFR WILL PERSIST ACRS THE FCST AREA THRU 06Z THURSDAY. LOW
CIGS AND AREAS OF -RADZ/BR/FG THIS MRNG INTO THE EARLY AFTN HRS.
AS LOW PRES WORKS NWD LATER THIS AFTN...WE`LL SEE PCPN SWITCHOVER
TO SNOW DURING THE MID/LATE AFTN ACRS CNTRL NY AND THIS EVNG ACRS
NE PA. WINDS LGT NRLY THIS MRNG...INCRSNG TO 10-15 KTS THIS EVNG.
OUTLOOK...
THU...VFR.
FRI...MVFR SNOW SHWRS
SAT...VFR OCNL MVFR SNOW SHWRS.
SUN...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJP
NEAR TERM...DJP
SHORT TERM...RRM
LONG TERM...DGM
AVIATION...
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1247 AM EST WED DEC 7 2011
.SYNOPSIS...
DRIZZLE AND PATCHY FOG WILL BE OVER THE REGION OVERNIGHT, AS A
STORM SYSTEM SLOWLY PULLS EASTWARD. A STRONGER STORM WILL DEVELOP
IN THE MID ATLANTIC REGION WEDNESDAY AFTERNOON THEN TRACK
NORTHEAST ALONG THE COAST WEDNESDAY NIGHT. A RAIN AND SNOW MIX IS
LIKELY INITIALLY WEDNESDAY EVENING, THEN AS COLDER AIR GETS DRAWN
INTO THE SYSTEM A PERIOD OF SNOW IS LIKELY, WITH SEVERAL INCHES OF
SNOW POSSIBLE FOR THE WESTERN CATSKILLS AND POCONOS.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
THE FRONT IS ALONG OUR EXTREME EASTERN BORDER AT THIS HOUR.
TEMPERATURES REMAIN IN THE MID 50S OVER SULLIVAN COUNTY NY, WHILE
BROOME AND CHENANGO IS NOW IN THE UPPER 30S.
PATCHY DENSE FOG IS BEING OBSERVED, MAINLY ALONG THE HIGHER
ELEVATIONS. THE SURFACE OBS SHOW THAT THE DENSE FOG IS NOT
WIDESPREAD, SO WE WILL HOLD OFF ON A DENSE FOG ADVISORY.
SPOTTY DRIZZLE CONTINUES BEHIND THE FRONT. TEMPERATURES ARE
HOLDING IN THE MIDDLE TO UPPER 30S ACROSS OUR WESTERN AND CENTRAL
ZONES. LATEST RUC13 AND HRRR GUIDANCE SUGGESTS TEMPERATURES WILL
BARELY FALL OVERNIGHT, SO WE ARE NOT ANTICIPATING FREEZING
DRIZZLE. A FEW ISOLATED REPORTS ARE POSSIBLE...BUT THAT WOULD NOT
BE IN THE NEXT FEW HOURS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY/...
WEDNESDAY/WEDNESDAY NIGHT...UPPER LEVEL WAVE SHARPENS IN THE TN
VALLEY THEN MOVES INTO THE MID ATLANTIC REGION BY WEDNESDAY
EVENING. SFC LOW DEVELOPS IN RESPONSE TO THIS UPPER LEVEL WAVE
AND DEEPENS AS IT MOVES INTO THE MID ATLANTIC REGION BY WEDNESDAY
AFTERNOON. THIS FEATURE THEN TRACK NORTHEAST OFF THE SOUTHERN NJ
COAST AND INTO COASTAL NEW ENGLAND BY 12Z THURSDAY. MODEL TRENDS
HAVE BEEN TO TRACK SYSTEM FURTHER NORTH AND WEST LEADING TO MORE
PRECIP FOR FORECAST AREA. SNOW FORECAST VERY DIFFICULT WITH THIS
SYSTEM DUE TO FAST MOTION AND INITIALLY PRECIP WILL BE IN THE FORM
OF RAIN/SNOW THEN CHANGE TO ALL SNOW AS COLD AIR DEEPENS BEHIND
WAVE. FOR NOW IT LOOKS LIKE AND ADVISORY SNOWFALL FOR THE HIGHER
TERRAIN OF THE WESTERN CATSKILLS AND POCONOS WITH 3-5 INCHES
LIKELY. IF THE CONSENSUS TRACK CHANGES IT WILL HAVE A BIG IMPACT
ON TOTAL SNOW ACCUMS.
THURSDAY THROUGH FRIDAY...BEHIND THIS WAVE COLDER AIR WILL SPREAD
ACROSS CENTRAL NEW YORK WITH CONDITIONS MARGINAL FAVORABLE FOR
SOME LAKE EFFECT SNOW THURSDAY AFTERNOON THROUGH THURSDAY NIGHT.
WITH W/SW FLOW ACTIVITY WILL RESIDE MAINLY OVER NRN ONEIDA COUNTY
AND PARTS OF STEUBEN COUNTY AND THE FINGER LAKES REGION FROM LAKE ERIE.
ON FRIDAY THE NEXT UPPER LEVEL TROF WILL APPROACH THE REGION FROM
THE UPPER GREAT LAKES. WILL CONTINUE WITH CHC POPS FOR ALL BUT FAR
SE FA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
XNTDD PD BEGINS WITH A NW FLOW OF COLD AIR AND PSBL LE SNOW SHWRS
FOR MUCH OF THE AREA. THIS CONTS INTO SAT AS THE BASE OF THE UPR
TROF MVES THRU. GRADUAL WRM UP WITH DRIER AIR BEGINS LATE
SUN...BUT RDG IS FLAT AND WSW FLOW IS SLOW TO BRING HIER TEMPS TO
THE AREA. SOME LE MAY LINGER ACROSS THE NRN ZONES INTO SUN. WRMR
ON MON WITH THE SFC HI OFF TO THE EAST AND CONTD DRY WSW FLOW. H8
TEMPS CLIMB ABOVE 0C. COLD FNT ON TUES WILL BRING BACK THE PSBLTY
OF SOME LGT RAIN OR SNOW SHWRS...AND SOME WEAK LAKE ENHANCEMENT.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
WDSPRD IFR WILL PERSIST ACRS THE FCST AREA THRU 06Z THURSDAY. LOW
CIGS AND AREAS OF -RADZ/BR/FG THIS MRNG INTO THE EARLY AFTN HRS.
AS LOW PRES WORKS NWD LATER THIS AFTN...WE`LL SEE PCPN SWITCHOVER
TO SNOW DURING THE MID/LATE AFTN ACRS CNTRL NY AND THIS EVNG ACRS
NE PA. WINDS LGT NRLY THIS MRNG...INCRSNG TO 10-15 KTS THIS EVNG.
OUTLOOK...
THU...VFR.
FRI...MVFR SNOW SHWRS
SAT...VFR OCNL MVFR SNOW SHWRS.
SUN...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJP
NEAR TERM...DJP
SHORT TERM...RRM
LONG TERM...DGM
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1232 AM EST WED DEC 7 2011
.SYNOPSIS...
MILD CONDITIONS ACCOMPANIED BY SHOWERS AND A FEW THUNDERSTORMS CAN
BE EXPECTED BY THIS AFTERNOON...PREVAILING INTO EVENING AHEAD OF
AN APPROACHING COLD FRONT. COLDER AIR WILL SPILL ACROSS THE REGION
BEGINNING THURSDAY...BRINGING CHILLY TEMPERATURES MORE TYPICAL OF
EARLY DECEMBER THROUGH MUCH OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 944 PM TUESDAY...LATEST HRRR MODEL INDICATES POSSIBLE PCPN
ACROSS THE ADJACENT ATLANTIC WATERS LATE TONIGHT THAT COULD NIP THE
ILM COASTAL COUNTIES. TO ACCOMMODATE THIS POSSIBILITY...WILL
INDICATE LOW POPS FOR THE AREA AROUND AND INCLUDING CAPE FEAR. SW
FLOW ALOFT...AND SE-S FLOW AT THE LOWER LEVELS...WILL BOTH PROVIDE
THE NECESSARY MOISTURE FOR INCREASED CLOUD COVER. COULD SEE
WIDESPREAD 60S FOR TONIGHTS LOWS WHICH ARE THE NORMAL DAYTIME HIGHS
FOR THIS TIME OF THE YEAR...BIZARRE. FRONTAL DYNAMICS AND WEAK
IMPULSES OR S/W TROFS ALOFT RIDING NE ALONG IT...ARE PROGGED TO
REMAIN WEST OF THE ILM CWA OVERNIGHT. SOUTHERLY WINDS TO INCREASE
TONIGHT AHEAD OF THE FRONT...THUS PREVENTING ANY WIDESPREAD FOG
DEVELOPMENT.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 PM TUESDAY...A COLD FRONT WILL MOVE THROUGH THE AREA
WEDNESDAY AFTERNOON AND EVENING...BRINGING SCATTERED TO NUMEROUS
SHOWERS AND PERHAPS ISOLATED THUNDERSTORMS. THE GREATEST
POTENTIAL FOR PRECIPITATION LOOKS TO RUN FROM ABOUT 18Z THROUGH
ABOUT 03Z WITH WARM TEMPERATURES CONTINUING. AFTER THE FRONT PASSES
DURING THE EVENING...STRONG COLD AIR ADVECTION WILL
COMMENCE...USHERING IN A RETURN TO BELOW NORMAL TEMPERATURES FOR
THURSDAY AND THURSDAY NIGHT UNDER MAINLY CLEAR SKIES.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 300 PM TUESDAY...A RATHER DYNAMIC WEATHER PATTERN IS EXPECTED
TO UNFOLD THROUGH THE EXTENDED PERIOD WITH AT LEAST TWO UPPER-LEVEL
FEATURES EXPECTED TO BRING CLOUDS AND SOME CHANCES FOR RAIN.
EXTENDED-RANGE MODELS (GFS AND ECMWF) ARE IN GOOD AGREEMENT FRIDAY
AND SATURDAY...BUT THEN DIVERGE BEGINNING SUNDAY.
TWO ARCTIC HIGHS FRIDAY...ONE SITUATED EAST OF NEW ENGLAND AND A
SECOND OVER THE CENTRAL PLAINS STATES...WILL BE SEPARATED BY A
TROUGH/FRONT LYING JUST OFF THE CAROLINA COAST. AN UPPER LEVEL
DISTURBANCE STREAKING NORTHEAST FRIDAY EVENING WILL HELP INDUCE LOW
PRESSURE TO DEVELOP OFF THE COAST WITH A SHORT WINDOW FOR RAIN
POSSIBLE ALONG THE NC COAST AND OFFSHORE. OUR POP IS ONLY 20 PERCENT
AT ILM...WITH 10% POPS FARTHER WEST. AN ARCTIC COLD FRONT WILL PUSH
THROUGH THE AREA LATE FRIDAY NIGHT...FOLLOWED BY ARCTIC HIGH
PRESSURE BUILDING IN THROUGH MONDAY WITH MAINLY CLEAR SKIES. THE
ECMWF BEGINS TO DIVERGE FROM THE GFS HERE WITH ITS FORECAST POSITION
OF THE HIGH LYING A COUPLE HUNDRED MILES FARTHER SOUTH THAN THE GFS.
THE MAIN IMPLICATION HERE IS THAT A HIGH CENTERED CLOSER TO THE
CAROLINAS WOULD LIKELY GIVE US LIGHTER OVERNIGHT WIND SPEEDS AND
COLDER LOW TEMPERATURES SATURDAY AND SUNDAY NIGHTS.
MODELS DIVERGE FURTHER MONDAY INTO TUESDAY WITH THEIR HANDLING OF A
SHORTWAVE TROUGH MOVING NORTHEAST FROM TEXAS INTO THE CAROLINAS. THE
ECMWF DEVELOPS A LARGER AREA OF OVERRUNNING RAIN MONDAY INTO
TUESDAY...WHILE THE GFS REMAINS MUCH DRIER. THIS LIKELY DUE TO
DIFFERENCES IN DEGREE OF BACKING IN THE 850/700 MB FLOW...VERY
DIFFICULT TO DISCERN THIS FAR IN ADVANCE. WE HAVE INTRODUCED A 30
POP (RAIN) LATE MONDAY INTO TUESDAY ACKNOWLEDGING BETTER RUN-TO-RUN
CONSISTENCY IN THE ECMWF...BUT TEMPERED BY COLLABORATIVE THRESHOLDS
WITH SURROUNDING NWS OFFICES WHO ARE MAINTAINING A DRY FORECAST.
FORECAST TEMPERATURES THROUGH THE EXTENDED RANGE ARE GENERALLY A FEW
DEGREES WARMER IN THE ECMWF THAN IN THE GFS (WARMER 1000-500 MB
THICKNESSES AND WARMER 850 MB TEMPS). THE ONLY EXCEPTION MAY BE
SATURDAY AND SUNDAY NIGHTS WHERE THE FARTHER SOUTH POSITION OF THE
ARCTIC HIGH IN THE ECMWF COULD PRODUCE SOMEWHAT COOLER NIGHTTIME
LOWS THAN THE 12Z GFS INDICATES. OTHERWISE LATEST GFS MOS NUMBERS
ARE REASONABLE.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 06Z...AS OF 06Z...MODERATE CONFIDENCE OVERNIGHT WITH MVFR STRATUS POSSIBLE
AT THE COAST. COLD FRONT WILL BRING PRECIP AND RESTRICTIONS ON
WEDNESDAY.
CAROLINAS REMAIN ENTRENCHED BETWEEN COLD FRONT CRAWLING EASTWARD THE
MTNS...AND HIGH PRESSURE RIDGING DOWN THE ATLANTIC SEA BOARD.
TIGHTENED PG IS KEEPING WINDS ELEVATED SO DO NOT EXPECT MUCH IN THE
WAY OF FOG OVERNIGHT...BUT HIGHER TD/S MAY PROMOTE A STRATUS THREAT.
HOWEVER...GUIDANCE HAS BACKED OFF CONSIDERABLY ON IFR
POTENTIAL...AND HAVE NOT SEEN ANY IFR STRATUS UPSTREAM. FOR THIS
REASON HAVE REMOVED IFR FROM INLAND TERMINALS AND EXPECT VFR TO BE
PREDOMINANT OVERNIGHT AT FLO/LBT. ILM/CRE/MYR MAY SEE AN ISOLATED
SHOWER OR MVFR CIG AS FLOW REMAINS MORE ONSHORE THAN PREVIOUSLY
ANTICIPATED. HAVE TEMPO MVFR AT ALL THE COASTAL TERMINALS FOR
POTENTIAL...BUT DO NOT EXPECT WIDESPREAD RESTRICTIONS OVERNIGHT.
WINDS WILL PERSIST FROM THE SOUTH AROUND 5 KTS.
AFTER SUNRISE EXPECT VFR...AND THE COLD FRONT WILL BEGIN TO IMPACT
THE AREA FROM THE WEST IN THE AFTN. THE CONTINUALLY TIGHTENING
GRADIENT WILL PRODUCE WINDS FROM THE S/SW OF 10-15 KTS GUSTING UP TO
25 KTS. SHOWERS WILL OVERSPREAD THE TERMINALS...FIRST AT LBT/FLO BY
LATE AFTN AND TO THE COAST DURING THE EVENING...AND HAVE INDICATED
CB AT THE INLAND TERMINALS WHERE SUFFICIENT INSTABILITY IN SOUNDINGS
SHOWS A POTENTIAL TSTM THREAT. PRECIP INDUCED VSBYS AND CIGS OF AT
LEAST MVFR ARE LIKELY...WITH IFR POSSIBLE IN THE HEAVIEST RAIN. COLD
FRONT WILL RACE THROUGH DURING WEDNESDAY NIGHT...TURNING WINDS TO
THE WEST BUT REMAINING STRONG THROUGH THE END OF THIS VALID PERIOD.
SKY CONDITIONS WILL RAPIDLY IMPROVE TO VFR BEHIND FROPA AS WELL.
EXTENDED OUTLOOK...VFR THROUGH THE EXTENDED.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 944 PM TUESDAY...MODELS STILL INDICATING/PROGGING HIGHER WIND
SPEEDS ACROSS THE WATERS...WITH A REFLECTION WITH BUILDING SEAS.
OVERALL...MODELS THIS EARLY WINTER SEASON HAVE BEEN HAVING A
SOMEWHAT DIFFICULT TIME WITH OVER-FORECASTING WIND SPEEDS AND
BUILDING SEAS ACROSS THE ILM COASTAL WATERS IN THE WARM SECTOR AHEAD
OF APPROACHING STRONG COLD FRONTS. EXPECT SOME BLEEDING OF HIGHER
SEAS OFFSHORE INTO THE OUTER WATERS OF THE COASTAL WATERS...DUE TO
SSTS OFFSHORE IN THE 70S ALLOWING STRONGER WINDS ALOFT TO MIX TO THE
OCEAN SFC. S-SSW WINDS 10 TO 15 KT...AND SEAS 2 TO 4 FT...LIKELY
BUILDING TO 3 TO 5 FT...WITH THE HIGHER SEAS RESERVED ACROSS THE
OUTER WATERS. COULD OBSERVE SHRA OVER THE OFFSHORE WATERS TRACK INTO
THE COASTAL WATERS DURING THE OVERNIGHT PERIOD.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 PM TUESDAY...WINDS STEADILY INCREASE DURING THE DAY
WEDNESDAY FROM AROUND 20 KNOTS TO A RANGE OF 25-30 KNOTS BY
WEDNESDAY EVENING. GFS IS ADVERTISING 35 TO 40 KNOTS IN WAA BUT
WITH THE COOLER WATER TEMPERATURES...THIS LOOKS OVERDONE. THURSDAY
WILL SEE AN OFFSHORE FLOW THAT WEAKENS THROUGHOUT THE DAY. SEAS WILL
RAMP UP AS WELL WITH SOME EIGHT FOOTERS POSSIBLE LATE WEDNESDAY INTO
WEDNESDAY NIGHT BEFORE SUBSIDING TO 3 TO 4 FT THURSDAY AFTERNOON AND
EVENING. A SMALL CRAFT ADVISORY HAS BEEN RAISED FOR 18Z WEDNESDAY
THROUGH 12Z THURSDAY.
LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 300 PM TUESDAY...AN EXTENDED PERIOD OF MODERATE TO STRONG
NORTHEAST WINDS ARE EXPECTED THROUGH THE WEEKEND AS ARCTIC HIGH
PRESSURE BUILDS INTO THE REGION. AN INVERTED TROUGH OFF THE COAST
FRIDAY WILL BE KICKED FARTHER OFFSHORE AS AN ARCTIC COLD FRONT MOVES
THROUGH THE AREA SATURDAY MORNING. THE ARCTIC HIGH WILL MOVE NORTH
OF THE AREA THROUGH THE WEEKEND WITH STRONG MODERATE TO STRONG NORTH
TO NORTHEAST WINDS. THESE WINDS WILL BUILD SEAS TO AS MUCH AS 6-7
FEET IN THE OUTERMOST PORTIONS OF THE COASTAL WATERS SATURDAY NIGHT
INTO SUNDAY...WITH LESS AGITATED CONDITIONS EXPECTED CLOSER TO SHORE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 1 PM WEDNESDAY TO 8 AM EST
THURSDAY FOR AMZ250-252-254-256.
&&
$$
NEAR TERM...DCH/8
SHORT TERM...RAN
LONG TERM...TRA
AVIATION...JDW/8
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
134 AM EST WED DEC 7 2011
.SYNOPSIS...
A WAVY FRONTAL BOUNDARY OVER CENTRAL PENNSYLVANIA WILL MOVE
SLOWLY TO THE SOUTH AND EAST OVERNIGHT. A DYNAMIC LOW PRESSURE
SYSTEM WILL DEVELOP IN THE LEE OF THE CENTRAL APPALACHIANS BY THIS
AFTERNOON AND INTENSIFY AS IT TRACKS NORTHEASTWARD OVER THE
DELMARVA PENINSULA...BEFORE ACCELERATING NORTHWARD ALONG THE NEW
ENGLAND COAST INTO THE CANADIAN MARITIMES BY THURSDAY MORNING.
RAIN WILL CHANGE TO SNOW FROM NORTHWEST TO SOUTHEAST BY THE
EVENING...AS COLD AIR WRAPS INTO THE BACKSIDE OF THE SYSTEM. SNOW
WILL END EARLY THURSDAY WITH SEASONABLY COLD AND MAINLY DRY
CONDITIONS PREVAILING INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 8 AM THIS MORNING/...
AT 06Z..SFC OBS AND RUC DATA SUGGEST WK WAVE OF LOW PRES IS BTWN
SEG AND RDG...WITH TRAILING WAVY FRONTAL BNDRY TRAILING TO THE SW
ALONG THE APPALACHIANS. AREAS OF DZ AND LGT RAIN WILL PERSIST IN
MOST AREAS PRIOR TO 08Z BEFORE RAIN SHIELD SURGING NEWD ACRS WV
OVERSPREADS THE SRN 1/2 TO 1/3 OF THE CWA. SATL ANAL AND TRENDS
SHOW THE MID-UPPER LOW TRACKING EWD ACRS ERN OK/NE TX/WRN AR
BEGINNING TO INTENSIFY AS IT PHASES WITH 150KT JET ACRS THE SE
U.S. WV LOOPS SHOWS THE UPPER TROUGH DIGGING TWD THE LWR TN VLY
WITH DOWNSTREAM IR ENHANCEMENT/COOLING CLOUD TOPS ALONG THE
S-CENTRAL APPALACHIANS FM TN TO WV WITH STRENGTHENING UPPER LVL
DIFL. RDR TRENDS APPEAR TO BE AHEAD OF NEAR TERM MDL GUID WHICH IS
NOT SURPRISING GIVEN THE PROGRESSIVE NATURE OF THIS SYS AND DEEP
WAA OUT AHEAD OF THE H5 TROUGH. RDR TRENDS ALSO SUGGEST THE QPF
AXIS MAY BE SETTING UP A LITTLE FURTHER N THAN DEPICTED BY THE
GUID. HOURLY TEMPERATURES HAVE FALLEN INTO THE UPPER 30S BEHIND
THE FRONT OVR THE LAUREL HIGHLANDS AND NW MTNS...BUT READINGS
SHOULD STAY ABV THE FZG MARK. HIGHEST POPS THROUGH 12Z ARE OVR
THE SRN TIER WITH 6-HR QPF AMTS LKLY IN THE 0.25 TO 0.50 INCH
RANGE PER MDL BLEND.
&&
.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM THURSDAY/...
MODEL SOLUTIONS CONTINUE TO BE SIMILAR WITH TIMING...PLACEMENT
AND EFFECTS FOR WEDNESDAY AND WEDNESDAY NIGHT. CONFIDENCE IN THE SHORT
TERM FCST HAS INCREASED MARKEDLY IN THE LAST 12-18 HRS.
SHARP POS-TILTED TROUGH OVER THE CENTRAL STATES WILL SWING VERY
QUICKLY TO A MERIDIONAL OR EVEN SLIGHT NEG TILT BY WED EVENING. A
SFC LOW WILL DEVELOP IN THE CAROLINAS AS THE HEIGHT FALLS OCCUR
TONIGHT AND VERY EARLY WED. THE DEEP MOISTURE FLOW FROM THE GULF
GETS CUT OFF FAIRLY QUICKLY...BUT THE ATLANTIC WILL KEEP THE
PRESSURES DROPPING. LACK OF DEEP/ANOMALOUS EASTERLY FLOW IS A
NEGATIVE FOR THIS STORM...BUT THE DYNAMICS ARE VERY POWERFUL.
SW-NE UPPER JET IS WELL OVER 100KTS. THE FAST NORTHEASTWARD
MOVEMENT OF THE STORM WILL LIMIT THE TIME PERIOD OF HEAVIEST
PRECIP. HOWEVER...THE DYNAMICS PULL MUCHO MOISTURE IN AND TEMPS
COOL VERY RAPIDLY FROM TOP DOWN. THEREFORE...A CHANGE FROM RAIN TO
SNOW WILL OCCUR FROM TOP DOWN. SFC TEMPS ARE STILL RATHER WARM FOR
ACCUMS TO OCCUR IN THE LOWER ELEVS - ESP THE LOWER SUSQ - UNTIL
LATE IN THE DAY...THOUGH.
NAM/GFS BUFKIT PROFILES ARE EXTREMELY WET IN THE SERN HALF OF THE
AREA...WITH VERY STRONG UPWARD OMEGAS IN THE MID LEVELS...RIGHT IN
BEST THE DENDRITIC SNOW GROWTH ZONE. THE STORM SHOULD END RATHER
QUICKLY FROM W-SE WED NIGHT. QPF IN THE COLD AIR AND HPC MANUAL
PROGS GIVES HIGH PROB OF A 2-5 INCH SNOWFALL FOR THE SOUTHERN HALF
OF THE STATE...AND 6+ ARE POSSIBLE IN THE HIGHER ELEVATIONS OF THE
LAURELS WHERE TEMPS ARE COLDER FIRST AND OVER THE POCONOS/SCHUYLKILL
CO WHERE THE SNOW LEVELS DROP FIRST IN THE EAST AND THE PRECIP
WILL LAST INTO THE MIDDLE OF THE NIGHT. WILL POST A WINTER STORM
WATCH FOR SOMERSET AND SCHUYLKILL COS. AGAIN...THE DRAWBACKS FOR
HEAVIER SNOW IN THE MORE-POPULOUS AREAS OF THE MID AND LOWER SUSQ
VALLEY WILL BE THE LATER TURNOVER TO SNOW AND THE WARM SFC TEMPS.
SNOW MAY FALL FOR A WHILE BUT MELT AS IT FALLS WED AFTN. THIS MAY
SOUND FAMILIAR. THE S-L RATIOS LOOK LIKE A NEAR 10:1 WITH A HEAVY
WETNESS TO IT AS THE SNOW GRABS LOTS OF SUPER- COOLED WATER ON THE
WAY DOWN FROM ON HIGH.
THINK ADVISORY SNOWFALL IS POSSIBLE FOR A STRIPE FROM THE LAURELS
THROUGH DAUPHIN AND SCHUYLKILL COUNTIES LATE WEDNESDAY AFTERNOON
THROUGH LATE WEDNESDAY NIGHT. INTENSE UPWARD VERTICAL MOTION IN
ADVANCE OF THE VIGOROUS UPPER WAVE SHOULD BRING A 4 TO 6 HOUR
PERIOD OF HEAVY PRECIPITATION...LIKELY SNOW...TO NORTHERN PORTIONS
OF THE SOUTH CENTRAL MOUNTAINS AND THE MIDDLE TO LOWER SUSQ. RIVER
VALLEY. CONFIDENCE IS INCREASING AT THIS TIME...BUT NOT
SUFFICIENTLY TO SADDLE ONCOMING SHIFT WITH ADDITIONAL HEADLINES AT
THIS TIME WITH 00Z CYCLE HAVING JUST BEGUN.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
POTENT BUT PROGRESSIVE LOW PRESSURE AREA FOR WED/WED NIGHT WILL
QUICKLY MOVE TO THE NEW ENGLAND COAST BY DAYBREAK THURS...WITH A
BRISK AND COLD WLY FLOW REGIME PREVAILING OVR CNTRL PA DURING THE
DAY. THIS SHOULD TRANSLATE INTO A BRIEF PD OF SNOW SHOWERS MAINLY
FOR THE NW MTNS EARLY GIVEN FAVORABLE DOWNWIND LAKE TRAJECTORIES
AND COLD CYC FLOW ALOFT. THE LLVL FLOW THU NIGHT INTO FRI BACKS
TO THE WSW AS A NRN STREAM TROUGH ROTATES INTO THE UPPER MIDWEST
AROUND THE BASE OF HUDSON BAY VORTEX.
A MSTR-STARVED COLD FNT MARKING THE LEADING EDGE OF THE UPPER
MIDWEST H5 TROUGH AND ACCOMPANYING SEASONABLY COLD /-12 TO -14C AT
850MB/ AIR ALOFT WILL CROSS THE AREA FRI NGT...WITH LITTLE
FANFARE OTHER THAN SOME LAKE ENHANCED/UPSLOPE SNOW SHOWERS ALONG
THE ALLEGHENIES. TEMPERATURES SHOULD BOTTOM ON SATURDAY AS THE CORE
UPPER TROUGH AXIS MOVES OVERHEAD...WITH MAXES IN THE UPPER 20S TO
MID 30S...ALONG WITH A BREEZY WESTERLY WIND. HIGH PRES WILL
OVERSPREAD THE REGION ON SUNDAY AND DOMINATE THE PATTERN INTO
EARLY NEXT WEEK. RETURN FLOW AROUND THE HIGH SHOULD LEAD TO
MODERATING TEMPS WITH FAIR WEATHER PERSISTING THROUGH MONDAY.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
COLD FRONT CONTINUES TO SLOWLY SAG THRU THE LOWER SUSQ VALLEY.
REGION CONTINUES TO BE AFFECTED BY WIDESPREAD IFR/MVFR. EXPECT
POOR FLYING CONDS TO CONTINUE THROUGH THE TAF PERIOD...WITH
PERIODS OF LIFR AND VLIFR CIGS/VSBYS POSSIBLE.
COLD AIR WILL PUSH IN FROM THE WEST TOMORROW WITH RAIN CHANGING
TO SNOW FROM WEST TO EAST. THE TRANSITION WILL BEGIN BY 12Z
ACROSS THE NORTHWEST AND SLOWLY PROGRESS EASTWARD WITH JST/AOO/UNV
CHANGING OVER BETWEEN ABOUT 20-23Z. THE SOUTHEASTERN TERMINALS
WILL CHANGE TO SNOW BETWEEN ABOUT 23-02Z WED EVENING.
BY 12Z THURSDAY CONDITIONS WILL BE IMPROVING RAPIDLY WITH THE
STORM SYSTEM EXITING THE EAST COAST.
OUTLOOK...
WED...WIDESPREAD IFR/MVFR CONTINUING WITH A RAIN CHANGING TO SNOW
SCENARIO FROM WEST TO EAST THROUGHOUT THE DAY.
THU...NO SIG WX EXPECTED.
FRI...PM SHSN POSSIBLE NW MTNS.
SAT/SUN...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM THIS AFTERNOON THROUGH LATE TONIGHT
FOR PAZ058.
WINTER STORM WATCH FROM 10 AM EST THIS MORNING THROUGH THIS
EVENING FOR PAZ033.
&&
$$
SYNOPSIS...DANGELO/STEINBUGL
NEAR TERM...DANGELO/DEVOIR/STEINBUGL
SHORT TERM...DANGELO/DEVOIR
LONG TERM...RXR/STEINBUGL
AVIATION...LA CORTE
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1034 PM CST TUE DEC 6 2011
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SYNOPSIS...SEASONABLY COLD AND VERY QUIET FOR THE EARLY PART OF
DECEMBER.
AMPLIFIED LNGWV PATTERN IN PLACE...WITH LARGE SCALE FLOW
DOMINATED BY MASSIVE RIDGE OVER THE ERN PAC. THE FLOW DOWNSTREAM
WAS SOMEWHAT SPLIT...WITH NRN STREAM MUCH STRONGER THAN THE
SRN...AND WITH TROFFING OVER ERN NOAM. THE TREND DURING THE FIRST
PART OF THE FCST PERIOD WL BE FOR BROAD ERN NOAM TROF TO EXPAND
SWD FM VORTEX IN THE HUDSON BAY RGN. THE SAME FEATURES SHOULD
REMAIN IN PLACE FOR THE LATTER HALF OF THE PERIOD...BUT WITH A
GRADUAL DECR IN AMPLITUDE.
TEMPS ACRS THE AREA HAVE COOLED TO NR NORMAL...AND WL CONT THE
DOWNSLIDE TO SOMEWHAT BLO NORMAL LEVELS AS THE UPR TROF DEEPENS
OVER THE RGN. ALTHOUGH THE N NOW HAS A DECENT SNOWCOVER...THE LACK
OF A WIDESPREAD DEEP SNOWCOVER ACRS THE ENTIRE REGION WL PREVENT
THIS FROM TURNING INTO A VERY COLD PERIOD. READINGS SHOULD REBOUND
DURING THE LATTER PART OF THE PERIOD AS UPR FLOW BECOMES MORE WLY.
GULF MOISTURE WL REMAIN TRAPPED WELL S OF THE AREA...AND DON/T SEE
ANY STG SYSTEMS IN THE FAST NWLY/WNWLY FLOW EITHER. EVEN THE
PROSPECT FOR LAKE-EFFECT LOOKS LOW AS FLOW WL BE RATHER WLY. SO
DON/T EXPECT MUCH PCPN DURING THE PERIOD.
&&
.SHORT TERM...TONIGHT AND WEDNESDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH
PRESSURE STRETCHING FROM THE CENTRAL GREAT PLAINS...ACROSS THE
GREAT LAKES...AND INTO QUEBEC THIS AFTERNOON. DESPITE THE SURFACE
HIGH...LOW CLOUDS OVER WESTERN AND CENTRAL WISCONSIN ARE
STUBBORNLY MOVING TO THE NORTHEAST. EARLIER FLURRY ACTIVITY OVER
THE DOOR PENINSULA IS ALSO FINALLY STARTING TO MOVE TO THE EAST AS
WELL. MEANWHILE...OVER THE LAKE WINNIPEG REGION...A DIVING
SHORTWAVE IS SENDING A WARM FRONT TO THE SOUTHEAST. AS THE SURFACE
HIGH DRIFTS TO THE SOUTH TONIGHT...CLOUDS AND TEMPS REMAIN THE
MAIN FORECAST CONCERNS.
TONIGHT...SURFACE HIGH PRESSURE WILL DRIFT TO THE SOUTH AS HEIGHT
FALLS OCCUR OVER SOUTH-CENTRAL CANADA AND THE FAR NORTHERN PLAINS.
LOW LEVEL SW WINDS WILL STRENGTHEN AND CONTINUE TO PUSH THE LOW
STRATUS TO THE NE. BASED ON THE LATEST SATELLITE OBS...TEND TO
THINK THE LOW STRATUS WILL STAY IN TACT OVER CENTRAL INTO EAST-
CENTRAL WISCONSIN THROUGH MID-EVENING WHILE NORTH- CENTRAL
WISCONSIN MAY ACTUALLY TURN PARTLY CLOUDY. UNLESS SOME HOLES
DEVELOP LATER THIS AFTERNOON...WILL TREND THE FORECAST THIS
DIRECTION. DRIER AIR IS THEN PROGGED TO PUSH THE STUBBORN STRATUS
TO THE EAST LATE THIS EVENING AND OVERNIGHT. SOME HIGH CLOUDS MAY
ARRIVE LATE AHEAD OF A SHEAR SHORTWAVE DIVING OVER SOUTH-CENTRAL
CANADA. THE STRENGTHENING WIND FIELD AND CLOUD COVER WILL KEEP
TEMPS WARMER THAN LAST NIGHT...AND WILL GO UPPER SINGLE DIGITS
NORTH TO LOWER 20S SE.
WEDNESDAY...THE SHEARED WAVE WILL SLIDE SOUTHEAST OVER LAKE
SUPERIOR...AND PUSH A WEAKENING COLD FRONT ACROSS THE FORECAST
AREA DURING THE MORNING. WILL SEE SOME SCT TO BKN MID CLOUDS WITH
THE FRONT...BUT NO REAL THREAT OF SNOW SHOWERS EXCEPT OVER
NORTHERN VILAS WHERE WNW WINDS MAY SEND A SCT SNOW SHOWERS ALONG
THE U.P.-WISCONSIN BORDER. TEMPS A COUPLE DEGREES WARMER THAN
TODAY OFF OF A WARMER START IN THE MORNING.
.LONG TERM...WED NGT THROUGH NEXT TUE. TRENDED TEMPS DOWN A
LITTLE BOTH THU AND FRI AS FCST AREA WL BE DOMINATED BY COLD AIR
FLOWING SEWD FM CANADA. WLY FLOW SHOULD KEEP SIG LAKE-EFFECT NE OF
THE AREA. THE CANADIAN GLOBAL MODEL BROUGHT SOME PCPN ACRS E-C WI
ON THU NGT INTO FRI AS BAROCLINIC LEAF TYPE FEATURES SLIDES ACRS
THE AREA. THE FEATURE WAS ALSO AT LEAST HINTED AT ON THE REST OF
THE MODELS...BUT THEY WERE ALL WEAKER AND FARTHER S. SO CANADIAN
SEEMS LIKE AN OUTLIER AND WL STICK WITH DRY FCST.
&&
.AVIATION...CLOUDS CONTINUE TO BLANKET MUCH OF NORTHEAST WISCONSIN
LATE THIS EVENING. VFR CIGS WERE NOTED OVER EAST CENTRAL WISCONSIN
WHILE MVFR CIGS WERE OVER CENTRAL AND NORTH CENTRAL WISCONSIN. SAT
IMAGERY INDICATES THE BACK EDGE OF THE MVFR CIGS WITH SOME IFR
CIGS REMAINED FROM AROUND ASX TO SOUTHEAST MINNESOTA. INCREASING
SOUTHWEST WINDS MAY PRODUCE A FEW HOLES IN THE CLOUD COVER OVERNIGHT.
MORE VFR TO MVFR CLOUDS WITH A PASSAGE OF A COLD FRONT FOR
WEDNESDAY FOLLOWED WITH VFR CONDITIONS FOR WEDNESDAY NIGHT. WILL
REMOVE THE LLWS MENTION OVERNIGHT DUE TO GUSTY WINDS REPORTED OVER
WESTERN LOCATIONS LATE THIS EVENING.
TDH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
715 AM EST WED DEC 7 2011
UPDATED AVIATION DISCUSSION FOR 12Z TAFS
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS REVEAL AN ACTIVE NRN STREAM FLOW TAKING
SHAPE OVER WRN AND CENTRAL CANADA INTO THE NRN CONUS. ONE SHORTWAVE
MOVING THROUGH NRN ONTARIO AND THE NRN PLAINS WILL CONTINUE EAST
ACROSS THE UPR GREAT LAKES PUSHING A COLD FRONT ACROSS THE REGION
TODAY. A SECOND CLIPPER SHORTWAVE MOVING THROUGH ALBERTA IS
EXPECTED TO MOVE ACROSS THE UPPER GREAT LAKES LATE TONIGHT INTO
THURSDAY USHERING IN THE COLDEST AIR OF THE SEASON AND SETTING UP A
PROLONGED LAKE EFFECT SNOW EVENT FOR NORTHWEST UPPER MI AND POSSIBLY
SHORELINE AREAS FROM GRAND MARAIS EAST TO WHITEFISH POINT.
&&
.DISCUSSION...
MAIN FCST CONCERN IS LES POTENTIAL WITH THE FRONT/TROUGH MOVING
THROUGH THE AREA TODAY AND THEN SECONDARY CLIPPER SYSTEM/ARCTIC PUSH
MOVING THROUGH LATE TONIGHT INTO THURSDAY.
TODAY...SATELLITE TRENDS AND MODEL RH/Q-VECT CONV FIELDS SUGGEST
LOWER CLOUDS OVER WESTERN UPPER MI WILL CONTINUE TO SPREAD EAST
ACROSS THE REST OF THE FCST AREA LATER THIS MORNING. COMBINATION OF
LOW-LVL CONV AND MODERATE Q-VECT CONV ALONG INCOMING COLD FRONT AND
CAA BEHIND THE FRONT SHOULD BRING SOME LIGHT SNOW TO NRN SECTIONS OF
FCST AREA TODAY. LOOK FOR ANY LES ACCUMS GENERALLY LESS THAN AN
INCH.
PASSAGE OF CLIPPER SHORTWAVE LATE TONIGHT SHOULD PROVIDE A BRIEF
PERIOD OF ENHANCEMENT TO LES ACCUMS LATE TONIGHT INTO THURSDAY
MORNING AS 850 MB TEMPS LOWER TO AROUND -15C BY 12Z WED. SNOW GROWTH
ALSO LOOKS FAVORABLE AS THE DGZ WILL BE RIGHT IN THE BEST
OMEGA/UPWARD MOTION. GIVEN MODEL QPF AND SNOW/WATER RATIOS
APPROACHING 30/1 WOULD NOT BE SURPRISED TO SEE A QUICK 4-7 INCHES OF
LES OVER THE KEWEENAW PENINSULA AND PERHAPS OVER THE LAKE SUPERIOR
SHORELINE EAST OF PICTURED ROCKS WHERE A DOMINANT LES BAND COULD SET
UP IN AN INCREASINGLY CONVERGENT WRLY FLOW. INCREASING WINDS GUSTING
TO NEAR 30 MPH AT TIMES ON THURSDAY WILL ALSO SHARPLY REDUCE VSBYS
IN BLOWING SNOW AS WELL AS CAUSE DRIFTING OF SNOW ACROSS ROADS.
AFTER THE CLIPPER SHORTWAVE MOVES EAST THU MORNING...THE POTENTIAL
FOR HEAVIER LES BCMS LESS CERTAIN...AND THERE WILL LIKELY BE A LULL
IN THE SNOW FOR THU AFTERNOON INTO THU EVENING AS RDDG AND AN INFLUX
OF DRIER AIR FROM WEST OF THE LAKE MAY LIMIT LES ACCUMS.
BECAUSE OF THIS POSSIBLE LULL AND THE UNCERTAINTY OF DETAILS WITH
WHERE THE DOMINANT BAND WOULD SET UP LATE TONIGHT INTO THU MORNING
HAVE DECIDED TO JUST KEEP THE LES WATCH GOING FOR NRN
ONTONAGON...NRN HOUGHTON AND KEWEENAW COUNTIES FOR LATE TONIGHT INTO
FRI NIGHT. HOWEVER...WOULD NOT BE SURPRISED TO SEE A LES WARNING
ISSUED ON THE DAY SHIFT FOR THE ABOVE MENTIONED COUNTIES AND
POSSIBLY AN ADVISORY ISSUED FOR THE ERN ALGER AND NRN LUCE SHORELINE
AREAS.
LES COULD PICK UP AGAIN LATE THU NIGHT INTO FRI MORNING OVER THE
KEWEENAW PENINSULA AS MODELS SHOW THE MID-UPR LVL TROF AXIS MOVING
OVERHEAD PROVIDING ENHANCEMENT TO LES BANDS. 850 MB TEMPS NEAR -20C
AND INCREASED LOW-LVL CONVERGENCE WITH DEVELOPING LAND BREEZES WILL
LIKELY FOCUS ANOTHER DOMINANT LES BAND OVER KEWEENAW PENINSULA.
AGAIN SNOW GROWTH LOOKS PRETTY FAVORABLE AS OMEGA INTERSECTS DGZ.
LAND BREEZES MAY SPARE THE FAR ERN SHORELINE AREAS THE BRUNT OF
HEAVIER SNOW BY PUSHING BAND FAR ENOUGH OFFSHORE.
AS MID-LVL TROF AND DEEPER MOISTURE STARTS TO DEPART THE WESTERN
CWA...EXPECT LES TO BEGIN TO DIMINISH FRI AFTERNOON...BUT THERE WILL
STILL BE AT LEAST SOME ONGOING ACCUMULATION INTO FRI EVENING. WITH
WINDS SHIFTING MORE OUT OF THE WSW...EXPECT BEST BANDS TO BE OVER
THE NRN PORTIONS OF THE KEWEENAW AND OFFSHORE OF THE ERN CWA.
EXPECT LES TO COME TO AN END ON SAT...AS A CLIPPER SYSTEM DROPS
THROUGH SOUTHERN ONTARIO AND SHIFTS WINDS TO THE SW PRODUCING WAA
ALOFT. ANOTEHR CLIPPER SYSTEM AND ASSOC FRONT MAY BRING SOME MORE
MORE LIGHT SNOW TO THE AREA AGAIN ON MONDAY WITH SOME LIGHT LES
POSSIBLE INTO MONDAY NIGHT.
&&
.AVIATION /FOR THE 12Z TAF ISSUANCE/
LAKE EFFECT SNOW SHOWERS HAVE BEGUN AT CMX...DROPPING VIS DOWN TO
1SM ALREADY. IWD AND SAW ARE NOT IN SUCH A FAVORABLE PREDICAMENT
OVER THE NEXT 24 HOURS...AS THE MAINLY WESTERLY DOMINATING WINDS
KEEP THE LOWER CEILINGS/VIS SITUATED NEAR THE KEWEENAW PENINSULA.
THE STRONGEST WINDS WITH GUSTS OF 25 TO 30KTS WILL ALSO BE OVER CMX
TODAY...WITH OTHER SITES GUSTING AROUND 20KTS. OTHERWISE...SAW AND
IWD SHOULD REMAIN VFR OR HIGH END MVFR THROUGH THE PERIOD.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
WINDS MAINLY OUT OF A WESTERLY DIRECTION OVER 20KTS WILL BE COMMON
THROUGH MUCH OF THE PERIOD...ALONG WITH PLENTY OF COLD AIR WHICH
WILL RESULT IN THE POTENTIAL FOR FREEZING SPRAY TONIGHT INTO FRIDAY.
A TROUGH OF LOW PRESSURE ACROSS LS WILL EXIT EAST TODAY...BRINGING
AN END TO THE SW GALES OVER THE WESTERN HALF OF LS. WESTERLY GALES
MAY RETURN AROUND SUNRISE THURSDAY OVER THE WEST HALF...BEFORE
EXTENDING THROUGH CENTRAL AND EASTERN LS THROUGH EARLY THURSDAY
EVENING.
EXPECT STRONG HIGH PRESSURE ACROSS SW CANADA TO WEAKEN
ACROSS THE PLAINS STATES FRIDAY...WHILE EXTENDING A RIDGE ACROSS LS
BY FRIDAY NIGHT. LOW PRESSURE OVER MANITOBA SATURDAY MORNING WILL
SLIDE ACROSS ONTARIO SATURDAY AFTERNOON AND EVENING...WHILE DRAGGING
A TROUGH OVER LS. ANOTHER LOW PRESSURE SYSTEM...OVER THE DAKOTAS
SUNDAY MORNING...WILL LIKELY FILTER ACROSS LS SUNDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WATCH FROM LATE TONIGHT THROUGH LATE FRIDAY
NIGHT FOR MIZ001>003.
LAKE SUPERIOR...
GALE WARNING UNTIL 10 AM EST THIS MORNING FOR LSZ263-264-266.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...VOSS
DISCUSSION...VOSS
AVIATION...KF
MARINE...KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
629 AM EST WED DEC 7 2011
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS REVEAL AN ACTIVE NRN STREAM FLOW TAKING
SHAPE OVER WRN AND CENTRAL CANADA INTO THE NRN CONUS. ONE SHORTWAVE
MOVING THROUGH NRN ONTARIO AND THE NRN PLAINS WILL CONTINUE EAST
ACROSS THE UPR GREAT LAKES PUSHING A COLD FRONT ACROSS THE REGION
TODAY. A SECOND CLIPPER SHORTWAVE MOVING THROUGH ALBERTA IS
EXPECTED TO MOVE ACROSS THE UPPER GREAT LAKES LATE TONIGHT INTO
THURSDAY USHERING IN THE COLDEST AIR OF THE SEASON AND SETTING UP A
PROLONGED LAKE EFFECT SNOW EVENT FOR NORTHWEST UPPER MI AND POSSIBLY
SHORELINE AREAS FROM GRAND MARAIS EAST TO WHITEFISH POINT.
&&
.DISCUSSION...
MAIN FCST CONCERN IS LES POTENTIAL WITH THE FRONT/TROUGH MOVING
THROUGH THE AREA TODAY AND THEN SECONDARY CLIPPER SYSTEM/ARCTIC PUSH
MOVING THROUGH LATE TONIGHT INTO THURSDAY.
TODAY...SATELLITE TRENDS AND MODEL RH/Q-VECT CONV FIELDS SUGGEST
LOWER CLOUDS OVER WESTERN UPPER MI WILL CONTINUE TO SPREAD EAST
ACROSS THE REST OF THE FCST AREA LATER THIS MORNING. COMBINATION OF
LOW-LVL CONV AND MODERATE Q-VECT CONV ALONG INCOMING COLD FRONT AND
CAA BEHIND THE FRONT SHOULD BRING SOME LIGHT SNOW TO NRN SECTIONS OF
FCST AREA TODAY. LOOK FOR ANY LES ACCUMS GENERALLY LESS THAN AN
INCH.
PASSAGE OF CLIPPER SHORTWAVE LATE TONIGHT SHOULD PROVIDE A BRIEF
PERIOD OF ENHANCEMENT TO LES ACCUMS LATE TONIGHT INTO THURSDAY
MORNING AS 850 MB TEMPS LOWER TO AROUND -15C BY 12Z WED. SNOW GROWTH
ALSO LOOKS FAVORABLE AS THE DGZ WILL BE RIGHT IN THE BEST
OMEGA/UPWARD MOTION. GIVEN MODEL QPF AND SNOW/WATER RATIOS
APPROACHING 30/1 WOULD NOT BE SURPRISED TO SEE A QUICK 4-7 INCHES OF
LES OVER THE KEWEENAW PENINSULA AND PERHAPS OVER THE LAKE SUPERIOR
SHORELINE EAST OF PICTURED ROCKS WHERE A DOMINANT LES BAND COULD SET
UP IN AN INCREASINGLY CONVERGENT WRLY FLOW. INCREASING WINDS GUSTING
TO NEAR 30 MPH AT TIMES ON THURSDAY WILL ALSO SHARPLY REDUCE VSBYS
IN BLOWING SNOW AS WELL AS CAUSE DRIFTING OF SNOW ACROSS ROADS.
AFTER THE CLIPPER SHORTWAVE MOVES EAST THU MORNING...THE POTENTIAL
FOR HEAVIER LES BCMS LESS CERTAIN...AND THERE WILL LIKELY BE A LULL
IN THE SNOW FOR THU AFTERNOON INTO THU EVENING AS RDDG AND AN INFLUX
OF DRIER AIR FROM WEST OF THE LAKE MAY LIMIT LES ACCUMS.
BECAUSE OF THIS POSSIBLE LULL AND THE UNCERTAINTY OF DETAILS WITH
WHERE THE DOMINANT BAND WOULD SET UP LATE TONIGHT INTO THU MORNING
HAVE DECIDED TO JUST KEEP THE LES WATCH GOING FOR NRN
ONTONAGON...NRN HOUGHTON AND KEWEENAW COUNTIES FOR LATE TONIGHT INTO
FRI NIGHT. HOWEVER...WOULD NOT BE SURPRISED TO SEE A LES WARNING
ISSUED ON THE DAY SHIFT FOR THE ABOVE MENTIONED COUNTIES AND
POSSIBLY AN ADVISORY ISSUED FOR THE ERN ALGER AND NRN LUCE SHORELINE
AREAS.
LES COULD PICK UP AGAIN LATE THU NIGHT INTO FRI MORNING OVER THE
KEWEENAW PENINSULA AS MODELS SHOW THE MID-UPR LVL TROF AXIS MOVING
OVERHEAD PROVIDING ENHANCEMENT TO LES BANDS. 850 MB TEMPS NEAR -20C
AND INCREASED LOW-LVL CONVERGENCE WITH DEVELOPING LAND BREEZES WILL
LIKELY FOCUS ANOTHER DOMINANT LES BAND OVER KEWEENAW PENINSULA.
AGAIN SNOW GROWTH LOOKS PRETTY FAVORABLE AS OMEGA INTERSECTS DGZ.
LAND BREEZES MAY SPARE THE FAR ERN SHORELINE AREAS THE BRUNT OF
HEAVIER SNOW BY PUSHING BAND FAR ENOUGH OFFSHORE.
AS MID-LVL TROF AND DEEPER MOISTURE STARTS TO DEPART THE WESTERN
CWA...EXPECT LES TO BEGIN TO DIMINISH FRI AFTERNOON...BUT THERE WILL
STILL BE AT LEAST SOME ONGOING ACCUMULATION INTO FRI EVENING. WITH
WINDS SHIFTING MORE OUT OF THE WSW...EXPECT BEST BANDS TO BE OVER
THE NRN PORTIONS OF THE KEWEENAW AND OFFSHORE OF THE ERN CWA.
EXPECT LES TO COME TO AN END ON SAT...AS A CLIPPER SYSTEM DROPS
THROUGH SOUTHERN ONTARIO AND SHIFTS WINDS TO THE SW PRODUCING WAA
ALOFT. ANOTEHR CLIPPER SYSTEM AND ASSOC FRONT MAY BRING SOME MORE
MORE LIGHT SNOW TO THE AREA AGAIN ON MONDAY WITH SOME LIGHT LES
POSSIBLE INTO MONDAY NIGHT.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/
SW GRADIENT WINDS AHEAD OF APPROACHING COLD FRONT WILL SUPPORT LLWS
AT ALL TAF SITES OVERNIGHT. WINDS VEERING WRLY IN THE MORNING BEHIND
THE FRONT SHOULD BRING MVFR CIGS BACK INTO KIWD AND KCMX EARLY THIS
MORNING. FAVORABLE WRLY FLOW AT KCMX MAY RESULT IN WIND GUSTS
AOA 30 KTS AS WELL AS POSSIBLE LAKE EFFECT SNOW SHOWERS. DRIER AIR
WILL MOVE INTO KIWD WED MORNING AND KEEP LAKE EFFECT CLOUDS NORTH OF
THE SITE. KSAW WILL STAY VFR THROUGH THE PERIOD.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
WINDS MAINLY OUT OF A WESTERLY DIRECTION OVER 20KTS WILL BE COMMON
THROUGH MUCH OF THE PERIOD...ALONG WITH PLENTY OF COLD AIR WHICH
WILL RESULT IN THE POTENTIAL FOR FREEZING SPRAY TONIGHT INTO FRIDAY.
A TROUGH OF LOW PRESSURE ACROSS LS WILL EXIT EAST TODAY...BRINGING
AN END TO THE SW GALES OVER THE WESTERN HALF OF LS. WESTERLY GALES
MAY RETURN AROUND SUNRISE THURSDAY OVER THE WEST HALF...BEFORE
EXTENDING THROUGH CENTRAL AND EASTERN LS THROUGH EARLY THURSDAY
EVENING.
EXPECT STRONG HIGH PRESSURE ACROSS SW CANADA TO WEAKEN
ACROSS THE PLAINS STATES FRIDAY...WHILE EXTENDING A RIDGE ACROSS LS
BY FRIDAY NIGHT. LOW PRESSURE OVER MANITOBA SATURDAY MORNING WILL
SLIDE ACROSS ONTARIO SATURDAY AFTERNOON AND EVENING...WHILE DRAGGING
A TROUGH OVER LS. ANOTHER LOW PRESSURE SYSTEM...OVER THE DAKOTAS
SUNDAY MORNING...WILL LIKELY FILTER ACROSS LS SUNDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WATCH FROM LATE TONIGHT THROUGH LATE FRIDAY
NIGHT FOR MIZ001>003.
LAKE SUPERIOR...
GALE WARNING UNTIL 10 AM EST THIS MORNING FOR LSZ263-264-266.
GALE WARNING UNTIL 7 AM EST /6 AM CST/ THIS MORNING FOR LSZ162.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...VOSS
DISCUSSION...VOSS
AVIATION...KF
MARINE...KF
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
748 AM EST WED DEC 7 2011
.SYNOPSIS...
A COMPACT AND INTENSE UPPER TROUGH WILL MOVE FROM THE LOWER
MISSISSIPPI VALLEY INTO THE MID-ATLANTIC STATES BY THIS EVENING.
THIS WILL ALLOW A DYNAMIC LOW PRESSURE SYSTEM TO DEVELOP IN THE
LEE OF THE CENTRAL APPALACHIANS OVER NORTH CAROLINA AND VIRGINIA
BY THIS AFTERNOON AND INTENSIFY AS IT TRACKS NORTHEASTWARD OVER
THE DELMARVA PENINSULA BEFORE ACCELERATING NORTHWARD ALONG THE NEW
ENGLAND COAST INTO THE CANADIAN MARITIMES BY THURSDAY MORNING.
RAIN...HEAVY AT TIMES WILL CHANGE TO SNOW FROM NORTHWEST TO
SOUTHEAST AS COLD AIR WRAPS INTO THE BACKSIDE OF THE SYSTEM. SNOW
WILL END BY EARLY THURSDAY MORNING WITH SEASONABLY COLD AND MAINLY
DRY CONDITIONS PREVAILING INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
MADE A SLIGHT NWD ADJUSTMENT TO NEAR TERM QPF AXIS AND TWEAKED
INCREASED INTENSITY OF RA TO WDSPRD/MODERATE. THE LAURELS MAY
CHANGE OVER A LITTLE SOONER THAN CURRENTLY FCST 15-16Z VS. 17-18Z
OTHERWISE CURRENT FCST REMAINS ON TRACK.
SFC OBS AND RUC DATA INDICATE THE WAVY SFC FRONT HAS PUSHED EAST
OF THE LWR SUSQ VLY. HIGHS SHOULD BE REACHED EARLY THIS MORNING
WITH STEADY TO FALLING TEMPERATURES EXPECTED THROUGH THIS EVENING.
A BROAD AREA OF LGT TO MOD RNFL HAS OVERSPREAD MUCH OF THE CWA AS
EXPECTED MAINLY S/E OF DUJ-BGM LINE. SATL DATA SHOWS APPROACHING
MID-UPPER LEVEL SHORTWAVE TROUGH MOVG THRU THE ARKLATEX PHASING
WITH AN INTENSIFYING UPPER JET MAXIMA...RESULTING IN A WELL
DEFINED AREA OF UPPER LEVEL DIVERGENCE AND THUS SUPPORTING INC
CVRG OF PCPN. STRENGTHENING LG SCALE LIFT WILL ENHANCE PCPN OVR
S-CENTRAL PA NEAR AXIS OF ABOVE NORMAL PWATS. DETERMINISTIC MODEL
AND ENSEMBLE GUID IS NOW IN VERY GOOD AGREEMENT IN SHOWING A MOD
TO HVY PCPN AXIS SETTING UP OVR S-CNTRL PA THRU THE AFTN WITH A
HIGH PROBABILITY IN 1 INCH QPF.
THE INITIAL SURGE OF PCPN WILL BE IN THE FORM OF RAIN BUT LOWERING
HEIGHTS/THICKNESS VALUES SHOULD ALLOW PCPN TO TRANSITION FROM RAIN
TO SNOW...ESPECIALLY AT HIGHER ELEVATIONS. THE LAUREL HIGHLANDS
SHOULD CHANGEOVER FIRST AROUND EARLY AFTN WITH LOCALLY HVY SNFL
RATES SUPPORTING SEVERAL INCHES OF ACCUM BY THIS EVE. THE TIMING
OF COOLING AND SNOW DURATION WILL BE CRITICAL TO HOW MUCH SNOW
OCCURS. THE TRANSITION TO SNOW SHOULD OCCUR LATE THIS AFTN INTO
THE EARLY EVE FURTHER E ACRS THE CNTRL MTNS AND EVENTUALLY THE LWR
SUSQ VLY.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH 6 AM THURSDAY/...
THE TIMING OF COOLING WILL LKLY BE EVEN MORE IMPORTANT DURING THIS
PD AS FOCUS FOR SNFL SHIFTS EWD INTO CNTRL AND ERN PA. MODELS
GENERATE A ADDNL 0.50-1 INCH LIQUID EQUIVALENT OVR THIS AREA IN
THE 00-06Z TIMEFRAME...THE OPTIMUM WINDOW FOR SIG ACCUMS OVR
CNTRL AND ERN AREAS. WARM BL AND SFC TEMPS WILL EVENTUALLY BE
OVERCOME BY STG DYNAMIC COOLING AND ENHANCED PCPN/SNFL RATES ESP
IN COMMA HEAD/DEFORMATION ZONE NW OF SFC LOW TRACK...BUT
LIMITED/UNCERTAIN DURATION OF TEMPS COLD ENOUGH FOR SNOW WILL LKLY
RESULT IN COMPLICATED ELEVATION DEPENDENCE AND THUS LIMIT ACCUMS
TO SOME EXTENT IN VALLEY AREAS. THEREFORE ONLY UPGRADED TO WINTER
STORM WARNINGS FOR SOMERSET AND SCHUYLKILL WHERE PROBABILITIES
FOR HEAVY SNOW ARE GREATER OVR THE HIGHER TERRAIN OF THE LAURELS
AND POCONOS. ELSEWHERE AN ADVISORY SHOULD BE SUFFICIENT GIVEN THE
COMPLEX NATURE OF ACCUM DIFFS WITH ELEVATION AND UNCERTAINTY ASSOC
WITH TIMING CHANGEOVER/TRANSITION. FOLLOWING DAYS OF LOW
CONFIDENCE AND LARGE MDL SPREADS..THERE IS GOOD MODEL AGREEMENT ON
THE STORM TRACK AND THEREFORE USED A CONSENSUS APPROACH IN
CONSTRUCTING QPF/SNOW AMTS. FINALLY WITH THE THREAT OF 2+ INCH QPF
AND SATURATED GROUNDS ISSUED FLOOD WATCH IN COORDINATION WITH
LWX/PHI FOR A PTN OF THE LWR SUSQ VLY.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
AS THE STRONG LOW PRESSURE SYSTEM CONTINUES TO MOVE THROUGH THE EAST
COAST A MORE ZONAL PATTERN WILL EXTEND ACROSS PA THROUGH THURSDAY.
EXPECT SEVERAL MAINLY DRY SHORT WAVES TO PROPAGATE THROUGH THIS
WEEKEND. MSTR-STARVED COLD FNT MARKING THE LEADING EDGE OF THE UPPER
MIDWEST H5 TROUGH AND ACCOMPANYING SEASONABLY COLD /-12 TO -14C AT
850MB/ AIR ALOFT WILL CROSS THE AREA FRI NIGHT INTO SATURDAY...WITH
LITTLE FANFARE OTHER THAN SOME LAKE ENHANCED/UPSLOPE SNOW SHOWERS
ALONG THE ALLEGHENIES. LONG RANGE MODELS DIFFER ON TIMING WITH THE
NEXT LONG WAVE TROUGH DIPPING SOUTH FROM CANADA. MOST GEFS ENSEMBLES
MOVE IT THROUGH EARLY SUNDAY...WITH ONLY A FEW MEMBERS SLOWING IT
DOWN. THIS IS IN LINE WITH THE EC AND NAM. AS TROUGH AXIS MOVES
THROUGH THE REGION THERE REMAINS THE POSSIBILITY OF SCATTERED SNOW
SHOWERS SATURDAY. SYSTEM IS MOISTURE STARVED SO ANY SNOW WILL
BE LIGHT ACCUMULATIONS. COLD AIR MASS WILL ENTRENCH ITSELF OVER THE
AREA THIS WEEKEND WITH TEMPERATURES IN THE 30S. DRY SOUTH WESTERLY
FLOW BEHIND THE WEEKEND SYSTEM WILL LEAD TO WARMING MILD TEMPS
THROUGH THE FIRS HALF OF NEXT WEEK.
&&
.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
COLD FRONT CONTINUES TO SLOWLY SAG THRU THE LOWER SUSQ VALLEY.
REGION CONTINUES TO BE AFFECTED BY WIDESPREAD LIFR/MVFR.
ITERMITTENT SHOWERS AND PATCHY DENSE FOG WILL KEEP LOW CIGS
THROUGH THE MORNING AND EXPECT POOR FLYING CONDS TO CONTINUE
THROUGH THE TAF PERIOD...WITH PERIODS OF LIFR AND VLIFR CIGS/VSBYS
POSSIBLE.
COLD AIR WILL PUSH IN FROM THE WEST BY MID AFTERNOON WITH RAIN
CHANGING TO SNOW FROM WEST TO EAST. THE TRANSITION WILL BEGIN BY
15Z ACROSS THE NORTHWEST AND SLOWLY PROGRESS EASTWARD WITH
JST/AOO/UNV CHANGING OVER BETWEEN ABOUT 20-23Z. THE SOUTHEASTERN
TERMINALS WILL CHANGE TO SNOW BETWEEN ABOUT 23-03Z WED EVENING.
AFTER FRONTAL PASSAGE EXPECT CONDITIONS TO SIGINIFCANTLY
IMPROVE...AFTER 06Z. BY 12Z VFR CONDITIONS SHOULD DOMINATE AT ALL
TAF SITES. WIND SHEAR IS A POSSIBILITY WITH A LLJ ALONG THE
FRONT...EXPECT GUSTY WINDS AT AND BEHIND THE FRONT WITH WIND
GUSTS UP TO 30KTS POSSIBLE.
OUTLOOK...
WED...WIDESPREAD IFR/MVFR CONTINUING WITH A RAIN CHANGING TO SNOW
SCENARIO FROM WEST TO EAST THROUGHOUT THE DAY.
THU...NO SIG WX EXPECTED.
FRI...PM SHSN POSSIBLE NW MTNS.
SAT/SUN...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST
THURSDAY FOR PAZ012-018-019-025>028-034-035-037-041-042-045-
046-049>053.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 7 AM EST THURSDAY
FOR PAZ017-024.
WINTER STORM WARNING FROM 7 PM THIS EVENING TO 7 AM EST
THURSDAY FOR PAZ058.
WINTER STORM WARNING FROM NOON TODAY TO 7 AM EST THURSDAY FOR
PAZ033.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM EST
THURSDAY FOR PAZ036-056-057-059-063>066.
FLOOD WATCH FROM 1 PM EST THIS AFTERNOON THROUGH THURSDAY
MORNING FOR PAZ059-065-066.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...CERU
AVIATION...CERU
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
657 AM EST WED DEC 7 2011
.SYNOPSIS...
A COMPACT AND INTENSE UPPER TROUGH WILL MOVE FROM THE LOWER
MISSISSIPPI VALLEY INTO THE MID-ATLANTIC STATES BY THIS EVENING.
THIS WILL ALLOW A DYNAMIC LOW PRESSURE SYSTEM TO DEVELOP IN THE
LEE OF THE CENTRAL APPALACHIANS OVER NORTH CAROLINA AND VIRGINIA
BY THIS AFTERNOON AND INTENSIFY AS IT TRACKS NORTHEASTWARD OVER
THE DELMARVA PENINSULA BEFORE ACCELERATING NORTHWARD ALONG THE NEW
ENGLAND COAST INTO THE CANADIAN MARITIMES BY THURSDAY MORNING.
RAIN...HEAVY AT TIMES WILL CHANGE TO SNOW FROM NORTHWEST TO
SOUTHEAST AS COLD AIR WRAPS INTO THE BACKSIDE OF THE SYSTEM. SNOW
WILL END BY EARLY THURSDAY MORNING WITH SEASONABLY COLD AND MAINLY
DRY CONDITIONS PREVAILING INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
MADE A SLIGHT NWD ADJUSTMENT TO NEAR TERM QPF AXIS AND TWEAKED
INCREASED INTENSITY OF RA TO WDSPRD/MODERATE. THE LAURELS MAY
CHANGE OVER A LITTLE SOONER THAN CURRENTLY FCST 15-16Z VS. 17-18Z
OTHERWISE CURRENT FCST REMAINS ON TRACK.
SFC OBS AND RUC DATA INDICATE THE WAVY SFC FRONT HAS PUSHED EAST
OF THE LWR SUSQ VLY. HIGHS SHOULD BE REACHED EARLY THIS MORNING
WITH STEADY TO FALLING TEMPERATURES EXPECTED THROUGH THIS EVENING.
A BROAD AREA OF LGT TO MOD RNFL HAS OVERSPREAD MUCH OF THE CWA AS
EXPECTED MAINLY S/E OF DUJ-BGM LINE. SATL DATA SHOWS APPROACHING
MID-UPPER LEVEL SHORTWAVE TROUGH MOVG THRU THE ARKLATEX PHASING
WITH AN INTENSIFYING UPPER JET MAXIMA...RESULTING IN A WELL
DEFINED AREA OF UPPER LEVEL DIVERGENCE AND THUS SUPPORTING INC
CVRG OF PCPN. STRENGTHENING LG SCALE LIFT WILL ENHANCE PCPN OVR
S-CENTRAL PA NEAR AXIS OF ABOVE NORMAL PWATS. DETERMINISTIC MODEL
AND ENSEMBLE GUID IS NOW IN VERY GOOD AGREEMENT IN SHOWING A MOD
TO HVY PCPN AXIS SETTING UP OVR S-CNTRL PA THRU THE AFTN WITH A
HIGH PROBABILITY IN 1 INCH QPF.
THE INITIAL SURGE OF PCPN WILL BE IN THE FORM OF RAIN BUT LOWERING
HEIGHTS/THICKNESS VALUES SHOULD ALLOW PCPN TO TRANSITION FROM RAIN
TO SNOW...ESPECIALLY AT HIGHER ELEVATIONS. THE LAUREL HIGHLANDS
SHOULD CHANGEOVER FIRST AROUND EARLY AFTN WITH LOCALLY HVY SNFL
RATES SUPPORTING SEVERAL INCHES OF ACCUM BY THIS EVE. THE TIMING
OF COOLING AND SNOW DURATION WILL BE CRITICAL TO HOW MUCH SNOW
OCCURS. THE TRANSITION TO SNOW SHOULD OCCUR LATE THIS AFTN INTO
THE EARLY EVE FURTHER E ACRS THE CNTRL MTNS AND EVENTUALLY THE LWR
SUSQ VLY.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH 6 AM THURSDAY/...
THE TIMING OF COOLING WILL LKLY BE EVEN MORE IMPORTANT DURING THIS
PD AS FOCUS FOR SNFL SHIFTS EWD INTO CNTRL AND ERN PA. MODELS
GENERATE A ADDNL 0.50-1 INCH LIQUID EQUIVALENT OVR THIS AREA IN
THE 00-06Z TIMEFRAME...THE OPTIMUM WINDOW FOR SIG ACCUMS OVR
CNTRL AND ERN AREAS. WARM BL AND SFC TEMPS WILL EVENTUALLY BE
OVERCOME BY STG DYNAMIC COOLING AND ENHANCED PCPN/SNFL RATES ESP
IN COMMA HEAD/DEFORMATION ZONE NW OF SFC LOW TRACK...BUT
LIMITED/UNCERTAIN DURATION OF TEMPS COLD ENOUGH FOR SNOW WILL LKLY
RESULT IN COMPLICATED ELEVATION DEPENDENCE AND THUS LIMIT ACCUMS
TO SOME EXTENT IN VALLEY AREAS. THEREFORE ONLY UPGRADED TO WINTER
STORM WARNINGS FOR SOMERSET AND SCHUYLKILL WHERE PROBABILITIES
FOR HEAVY SNOW ARE GREATER OVR THE HIGHER TERRAIN OF THE LAURELS
AND POCONOS. ELSEWHERE AN ADVISORY SHOULD BE SUFFICIENT GIVEN THE
COMPLEX NATURE OF ACCUM DIFFS WITH ELEVATION AND UNCERTAINTY ASSOC
WITH TIMING CHANGEOVER/TRANSITION. FOLLOWING DAYS OF LOW
CONFIDENCE AND LARGE MDL SPREADS..THERE IS GOOD MODEL AGREEMENT ON
THE STORM TRACK AND THEREFORE USED A CONSENSUS APPROACH IN
CONSTRUCTING QPF/SNOW AMTS. FINALLY WITH THE THREAT OF 2+ INCH QPF
AND SATURATED GROUNDS ISSUED FLOOD WATCH IN COORDINATION WITH
LWX/PHI FOR A PTN OF THE LWR SUSQ VLY.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
AS THE STRONG LOW PRESSURE SYSTEM CONTINUES TO MOVE THROUGH THE EAST
COAST A MORE ZONAL PATTERN WILL EXTEND ACROSS PA THROUGH THURSDAY.
EXPECT SEVERAL MAINLY DRY SHORT WAVES TO PROPAGATE THROUGH THIS
WEEKEND. MSTR-STARVED COLD FNT MARKING THE LEADING EDGE OF THE UPPER
MIDWEST H5 TROUGH AND ACCOMPANYING SEASONABLY COLD /-12 TO -14C AT
850MB/ AIR ALOFT WILL CROSS THE AREA FRI NIGHT INTO SATURDAY...WITH
LITTLE FANFARE OTHER THAN SOME LAKE ENHANCED/UPSLOPE SNOW SHOWERS
ALONG THE ALLEGHENIES. LONG RANGE MODELS DIFFER ON TIMING WITH THE
NEXT LONG WAVE TROUGH DIPPING SOUTH FROM CANADA. MOST GEFS ENSEMBLES
MOVE IT THROUGH EARLY SUNDAY...WITH ONLY A FEW MEMBERS SLOWING IT
DOWN. THIS IS IN LINE WITH THE EC AND NAM. AS TROUGH AXIS MOVES
THROUGH THE REGION THERE REMAINS THE POSSIBILITY OF SCATTERED SNOW
SHOWERS SATURDAY. SYSTEM IS MOISTURE STARVED SO ANY SNOW WILL
BE LIGHT ACCUMULATIONS. COLD AIR MASS WILL ENTRENCH ITSELF OVER THE
AREA THIS WEEKEND WITH TEMPERATURES IN THE 30S. DRY SOUTH WESTERLY
FLOW BEHIND THE WEEKEND SYSTEM WILL LEAD TO WARMING MILD TEMPS
THROUGH THE FIRS HALF OF NEXT WEEK.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
COLD FRONT CONTINUES TO SLOWLY SAG THRU THE LOWER SUSQ VALLEY.
REGION CONTINUES TO BE AFFECTED BY WIDESPREAD IFR/MVFR. EXPECT
POOR FLYING CONDS TO CONTINUE THROUGH THE TAF PERIOD...WITH
PERIODS OF LIFR AND VLIFR CIGS/VSBYS POSSIBLE.
COLD AIR WILL PUSH IN FROM THE WEST TOMORROW WITH RAIN CHANGING
TO SNOW FROM WEST TO EAST. THE TRANSITION WILL BEGIN BY 12Z
ACROSS THE NORTHWEST AND SLOWLY PROGRESS EASTWARD WITH JST/AOO/UNV
CHANGING OVER BETWEEN ABOUT 20-23Z. THE SOUTHEASTERN TERMINALS
WILL CHANGE TO SNOW BETWEEN ABOUT 23-02Z WED EVENING.
BY 12Z THURSDAY CONDITIONS WILL BE IMPROVING RAPIDLY WITH THE
STORM SYSTEM EXITING THE EAST COAST.
OUTLOOK...
WED...WIDESPREAD IFR/MVFR CONTINUING WITH A RAIN CHANGING TO SNOW
SCENARIO FROM WEST TO EAST THROUGHOUT THE DAY.
THU...NO SIG WX EXPECTED.
FRI...PM SHSN POSSIBLE NW MTNS.
SAT/SUN...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST
THURSDAY FOR PAZ012-018-019-025>028-034-035-037-041-042-045-
046-049>053.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 7 AM EST THURSDAY
FOR PAZ017-024.
WINTER STORM WARNING FROM 7 PM THIS EVENING TO 7 AM EST
THURSDAY FOR PAZ058.
WINTER STORM WARNING FROM NOON TODAY TO 7 AM EST THURSDAY FOR
PAZ033.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM EST
THURSDAY FOR PAZ036-056-057-059-063>066.
FLOOD WATCH FROM 1 PM EST THIS AFTERNOON THROUGH THURSDAY
MORNING FOR PAZ059-065-066.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...CERU
AVIATION...CERU
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
621 AM EST WED DEC 7 2011
.SYNOPSIS...
A COMPACT AND INTENSE UPPER TROUGH WILL MOVE FROM THE LOWER
MISSISSIPPI VALLEY INTO THE MID-ATLANTIC STATES BY THIS EVENING.
THIS WILL ALLOW A DYNAMIC LOW PRESSURE SYSTEM TO DEVELOP IN THE
LEE OF THE CENTRAL APPALACHIANS OVER NORTH CAROLINA AND VIRGINIA
BY THIS AFTERNOON AND INTENSIFY AS IT TRACKS NORTHEASTWARD OVER
THE DELMARVA PENINSULA BEFORE ACCELERATING NORTHWARD ALONG THE NEW
ENGLAND COAST INTO THE CANADIAN MARITIMES BY THURSDAY MORNING.
RAIN...HEAVY AT TIMES WILL CHANGE TO SNOW FROM NORTHWEST TO
SOUTHEAST AS COLD AIR WRAPS INTO THE BACKSIDE OF THE SYSTEM. SNOW
WILL END BY EARLY THURSDAY MORNING WITH SEASONABLY COLD AND MAINLY
DRY CONDITIONS PREVAILING INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SFC OBS AND RUC DATA INDICATE THE WAVY SFC FRONT HAS PUSHED EAST
OF THE LWR SUSQ VLY. HIGHS SHOULD BE REACHED EARLY THIS MORNING
WITH STEADY TO FALLING TEMPERATURES EXPECTED THROUGH THIS EVENING.
A BROAD AREA OF LGT TO MOD RNFL HAS OVERSPREAD MUCH OF THE CWA AS
EXPECTED MAINLY S/E OF DUJ-BGM LINE. SATL DATA SHOWS APPROACHING
MID-UPPER LEVEL SHORTWAVE TROUGH MOVG THRU THE ARKLATEX PHASING
WITH AN INTENSIFYING UPPER JET MAXIMA...RESULTING IN A WELL
DEFINED AREA OF UPPER LEVEL DIVERGENCE AND THUS SUPPORTING INC
CVRG OF PCPN. STRENGTHENING LG SCALE LIFT WILL ENHANCE PCPN OVR
S-CENTRAL PA NEAR AXIS OF ABOVE NORMAL PWATS. DETERMINISTIC MODEL
AND ENSEMBLE GUID IS NOW IN VERY GOOD AGREEMENT IN SHOWING A MOD
TO HVY PCPN AXIS SETTING UP OVR S-CNTRL PA THRU THE AFTN WITH A
HIGH PROBABILITY IN 1 INCH QPF.
THE INITIAL SURGE OF PCPN WILL BE IN THE FORM OF RAIN BUT LOWERING
HEIGHTS/THICKNESS VALUES SHOULD ALLOW PCPN TO TRANSITION FROM RAIN
TO SNOW...ESPECIALLY AT HIGHER ELEVATIONS. THE LAUREL HIGHLANDS
SHOULD CHANGEOVER FIRST AROUND EARLY AFTN WITH LOCALLY HVY SNFL
RATES SUPPORTING SEVERAL INCHES OF ACCUM BY THIS EVE. THE TIMING
OF COOLING AND SNOW DURATION WILL BE CRITICAL TO HOW MUCH SNOW
OCCURS. THE TRANSITION TO SNOW SHOULD OCCUR LATE THIS AFTN INTO
THE EARLY EVE FURTHER E ACRS THE CNTRL MTNS AND EVENTUALLY THE LWR
SUSQ VLY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
THE TIMING OF COOLING WILL LKLY BE EVEN MORE IMPORTANT DURING THIS
PD AS FOCUS FOR SNFL SHIFTS EWD INTO CNTRL AND ERN PA. MODELS
GENERATE A ADDNL 0.50-1 INCH LIQUID EQUIVALENT OVR THIS AREA IN
THE 00-06Z TIMEFRAME...THE OPTIMUM WINDOW FOR SIG ACCUMS OVR
CNTRL AND ERN AREAS. WARM BL AND SFC TEMPS WILL EVENTUALLY BE
OVERCOME BY STG DYNAMIC COOLING AND ENHANCED PCPN/SNFL RATES ESP
IN COMMA HEAD/DEFORMATION ZONE NW OF SFC LOW TRACK...BUT
LIMITED/UNCERTAIN DURATION OF TEMPS COLD ENOUGH FOR SNOW WILL LKLY
RESULT IN COMPLICATED ELEVATION DEPENDENCE AND THUS LIMIT ACCUMS
TO SOME EXTENT IN VALLEY AREAS. THEREFORE ONLY UPGRADED TO WINTER
STORM WARNINGS FOR SOMERSET AND SCHUYLKILL WHERE PROBABILITIES
FOR HEAVY SNOW ARE GREATER OVR THE HIGHER TERRAIN OF THE LAURELS
AND POCONOS. ELSEWHERE AN ADVISORY SHOULD BE SUFFICIENT GIVEN THE
COMPLEX NATURE OF ACCUM DIFFS WITH ELEVATION AND UNCERTAINTY ASSOC
WITH TIMING CHANGEOVER/TRANSITION. FOLLOWING DAYS OF LOW
CONFIDENCE AND LARGE MDL SPREADS..THERE IS GOOD MODEL AGREEMENT ON
THE STORM TRACK AND THEREFORE USED A CONSENSUS APPROACH IN
CONSTRUCTING QPF/SNOW AMTS. FINALLY WITH THE THREAT OF 2+ INCH QPF
AND SATURATED GROUNDS ISSUED FLOOD WATCH IN COORDINATION WITH
LWX/PHI FOR A PTN OF THE LWR SUSQ VLY.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
AS THE STRONG LOW PRESSURE SYSTEM CONTINUES TO MOVE THROUGH THE EAST
COAST A MORE ZONAL PATTERN WILL EXTEND ACROSS PA THROUGH THURSDAY.
EXPECT SEVERAL MAINLY DRY SHORT WAVES TO PROPAGATE THROUGH THIS
WEEKEND. MSTR-STARVED COLD FNT MARKING THE LEADING EDGE OF THE UPPER
MIDWEST H5 TROUGH AND ACCOMPANYING SEASONABLY COLD /-12 TO -14C AT
850MB/ AIR ALOFT WILL CROSS THE AREA FRI NIGHT INTO SATURDAY...WITH
LITTLE FANFARE OTHER THAN SOME LAKE ENHANCED/UPSLOPE SNOW SHOWERS
ALONG THE ALLEGHENIES. LONG RANGE MODELS DIFFER ON TIMING WITH THE
NEXT LONG WAVE TROUGH DIPPING SOUTH FROM CANADA. MOST GEFS ENSEMBLES
MOVE IT THROUGH EARLY SUNDAY...WITH ONLY A FEW MEMBERS SLOWING IT
DOWN. THIS IS IN LINE WITH THE EC AND NAM. AS TROUGH AXIS MOVES
THROUGH THE REGION THERE REMAINS THE POSSIBILITY OF SCATTERED SNOW
SHOWERS SATURDAY. SYSTEM IS MOISTURE STARVED SO ANY SNOW WILL
BE LIGHT ACCUMULATIONS. COLD AIR MASS WILL ENTRENCH ITSELF OVER THE
AREA THIS WEEKEND WITH TEMPERATURES IN THE 30S. DRY SOUTH WESTERLY
FLOW BEHIND THE WEEKEND SYSTEM WILL LEAD TO WARMING MILD TEMPS
THROUGH THE FIRS HALF OF NEXT WEEK.
&&
.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
COLD FRONT CONTINUES TO SLOWLY SAG THRU THE LOWER SUSQ VALLEY.
REGION CONTINUES TO BE AFFECTED BY WIDESPREAD IFR/MVFR. EXPECT
POOR FLYING CONDS TO CONTINUE THROUGH THE TAF PERIOD...WITH
PERIODS OF LIFR AND VLIFR CIGS/VSBYS POSSIBLE.
COLD AIR WILL PUSH IN FROM THE WEST TOMORROW WITH RAIN CHANGING
TO SNOW FROM WEST TO EAST. THE TRANSITION WILL BEGIN BY 12Z
ACROSS THE NORTHWEST AND SLOWLY PROGRESS EASTWARD WITH JST/AOO/UNV
CHANGING OVER BETWEEN ABOUT 20-23Z. THE SOUTHEASTERN TERMINALS
WILL CHANGE TO SNOW BETWEEN ABOUT 23-02Z WED EVENING.
BY 12Z THURSDAY CONDITIONS WILL BE IMPROVING RAPIDLY WITH THE
STORM SYSTEM EXITING THE EAST COAST.
OUTLOOK...
WED...WIDESPREAD IFR/MVFR CONTINUING WITH A RAIN CHANGING TO SNOW
SCENARIO FROM WEST TO EAST THROUGHOUT THE DAY.
THU...NO SIG WX EXPECTED.
FRI...PM SHSN POSSIBLE NW MTNS.
SAT/SUN...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST
THURSDAY FOR PAZ012-018-019-025>028-034-035-037-041-042-045-
046-049>053.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 7 AM EST THURSDAY
FOR PAZ017-024.
WINTER STORM WARNING FROM 7 PM THIS EVENING TO 7 AM EST
THURSDAY FOR PAZ058.
WINTER STORM WARNING FROM NOON TODAY TO 7 AM EST THURSDAY FOR
PAZ033.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM EST
THURSDAY FOR PAZ036-056-057-059-063>066.
FLOOD WATCH FROM 1 PM EST THIS AFTERNOON THROUGH THURSDAY
MORNING FOR PAZ059-065-066.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...CERU
AVIATION...CERU
AREA FORECAST DISCUSSION
NWS ALBANY NY
557 PM EST WED DEC 7 2011
.SYNOPSIS...
A STORM SYSTEM WILL LIFT NORTHEAST FROM THE DELMARVA REGION THIS
EVENING...TO THE EAST END OF LONG ISLAND AROUND MIDNIGHT...AND
THEN INTO THE GULF OF MAINE THURSDAY MORNING. THIS STORM TRACK
WILL RESULT IN RAIN CHANGING TO SNOW THIS EVENING ACROSS MUCH OF
THE REGION WITH SIGNIFICANT SNOWFALL ACCUMULATIONS OVERNIGHT IN
MANY AREAS. THE HEAVIEST SNOW IS EXPECTED TO FALL ACROSS THE
NORTHERN TACONICS...EASTERN CATSKILLS...BERKSHIRES AND SOUTHERN
GREEN MOUNTAINS. HEAVY RAIN WILL CONTINUE TO FALL OVERNIGHT ACROSS
THE MID HUDSON VALLEY AND LITCHFIELD HILLS.
&&
.NEAR TERM /THROUGH THURSDAY/...
WINTER STORM WARNINGS ARE IN EFFECT FOR TONIGHT FOR THE EASTERN
CATSKILLS...NORTHERN TACONICS...BERKSHIRES AND SOUTHERN GREEN
MOUNTAINS AND WINTER WEATHER ADVISORIES IN EFFECT FOR THE
SOUTHEAST ADIRONDACKS...LAKE GEORGE SARATOGA REGION...EASTERN
MOHAWK VALLEY...SACANDAGA REGION...GREATER CAPITAL DISTRICT AND
CENTRAL TACONICS. A FLOOD WATCH IS IN EFFECT THROUGH THURSDAY
MORNING FOR THE MID HUDSON VALLEY...SOUTHERN TACONICS AND
LITCHFIELD HILLS.
SNOWFALL ACCUMULATIONS ARE GENERALLY EXPECTED TO BE 3 TO 8 INCHES
IN THE ADVISORY AREA AND 5 TO 12 INCHES IN THE WARNING AREA EXCEPT
ACROSS THE CENTRAL AND SOUTHEAST CATSKILLS...NORTHERN BERKSHIRES
AND HIGHER TERRAIN OF THE SOUTHERN GREEN MOUNTAINS WHERE 8 TO 16
INCHES OF SNOW IS EXPECTED. TOTAL RAINFALL AMOUNTS IN THE FLOOD
WATCH AREA ARE EXPECTED TO BE IN THE 1.75 TO 2.25 INCH RANGE.
AS OF 530 PM EST...CLOUD TOPS CONTINUE TO COOL ACROSS THE FA WITH
21Z KALB SOUNDING INDICATING A WARM TONGUE OF 4C AT AROUND 875 MB
WITH THE FREEZING LEVEL AT AROUND 775 MB OR 6.6 KFT. HAVE RECEIVED
A REPORT OF 1 INCH OF SNOW THUS FAR IN CHARLOTTEVILLE IN SCHOHARIE
COUNTY WITH HEAVY WET SNOW AND A TEMP OF 36 DEGREES AT AN
ELEVATION OF AROUND 1500 FEET. EXPECT A RAPID CHANGEOVER TO SNOW
THIS EVENING ACROSS MUCH OF THE FA MAINLY BETWEEN 00Z AND 03Z WITH
VERY HEAVY SNOW EXPECTED TO FALL DURING MUCH OF THE NIGHT BEFORE
TAPERING OFF LATE. THE ONLY AREAS WHICH ARE NOT EXPECTED TO
RECEIVE MUCH SNOW ARE FAR NORTHWEST PORTIONS OF THE FA INCLUDING
THE WESTERN ADIRONDACKS AND WESTERN MOHAWK VALLEY WHERE VERY
LITTLE QPF EXPECTED...NORTHERN FRINGE OF PCPN SHIELD AND FAR
SOUTHEAST PORTION OF FA WHICH WILL REMAIN TOO WARM FOR MUCH IN THE
WAY OF SNOW MAINLY FROM THE MID HUDSON VALLEY EAST TO THE
LITCHFIELD HILLS WHERE A FLOOD WATCH IS IN EFFECT.
MANY FAVORABLE FACTORS FOR HEAVY SNOW ARE IN PLACE ACROSS MUCH OF
THE FA WITH THE MOST SIGNIFICANT FACTORS BEING IMPRESSIVE
FRONTOGENESIS H8-H7 EXTENDING FROM THE CATSKILLS NORTHEAST TO
SOUTHERN VERMONT AT 00Z AND THEN SHIFTING TO AN ORIENTATION FROM
JUST EAST OF THE CAPITAL DISTRICT THROUGH THROUGH THE NORTHERN
BERKSHIRES INTO SOUTHERN VERMONT AT 06Z. AS THE EVENING WEARS ON
THE SNOW GROWTH REGION BECOMES INCREASINGLY MORE FAVORABLE WITH
THE -12 TO -18 C TEMP SLICING THROUGH A REGION OF +20 UBAR/SEC. IN
ADDITION IMPRESSIVE EPV EXISTS IN LOWER LEVELS ESPECIALLY BTWN 00Z
AND 06Z. THE LATEST HRRR COL MAX REFLECTIVITY ALSO INDICATES
IMPRESSIVE BANDED PCPN ESPECIALLY ACROSS THE HIGHER TERRAIN IN THE
WARNING AREA BETWEEN 03Z AND 06Z WITH THE BACK EDGE OF THE PCPN
SHIELD EXITING THE FA FROM WEST TO EAST BETWEEN 08Z AND 10Z.
EXPECT LOW TEMPS TONIGHT TO RANGE FROM THE MID 20S NORTHWEST TO
MID 30S FAR SOUTHEAST.
ON THURSDAY EXPECT IMPROVING CONDITIONS WITH HIGH PRESSURE MOVING
IN AND MAINLY DRY CONDITIONS WITH HIGHS RANGING FROM THE UPPER
20S TO LOWER 30S NORTHWEST TO LOWER 40S FAR SOUTHEAST.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
THU NT...BACKING LOW LEVEL WINDS SHOULD ALLOW ANY LINGERING SNOW
BANDS/SNOW SHOWERS TO SHIFT NORTHWARD INTO THE WESTERN
ADIRONDACKS...WITH ADDITIONAL ACCUMS POSSIBLE BEFORE INVERSION
HEIGHTS LOWER AND DIMINISH INTENSITY OF ANY SNOWBANDS.
ELSEWHERE...INITIALLY CLEAR TO PARTLY CLOUDY SKIES SHOULD BECOME
MOSTLY CLOUDY LATER AT NIGHT AS MID LEVEL ISENTROPIC LIFT INCREASES
AHEAD OF NEXT APPROACHING SHORTWAVE. EXPECT MINS TO FALL INTO THE
TEENS AND 20S...WARMEST ACROSS VALLEY REGIONS.
FRI-SAT...UPPER LEVEL TROUGH WILL APPROACH FROM THE W...AND PASS
ACROSS FRI NT. A SFC COLD FRONT ASSOCIATED WITH THIS FEATURE WILL
CROSS THE REGION LATE FRI OR FRI EVE...PRECEDED AND ACCOMPANIED BY
SNOW SHOWERS. THEN...BEHIND THE FRONT...BANDS OF SNOW SHOWERS AND
POSSIBLE SNOW SQUALLS WILL BE POSSIBLE...INITIALLY FAVORING PORTIONS
OF THE WESTERN MOHAWK VALLEY/SCHOHARIE VALLEY...THEN GRADUALLY
SHIFTING NORTHWARD INTO THE WESTERN ADIRONDACKS BY SAT. THERE IS
SOME POTENTIAL FOR LOCALLY HEAVY SNOWFALL AMTS WITHIN SOME OF THESE
BANDS...AND WILL MENTION THIS POSSIBILITY IN THE HWO...WITH GREATEST
THREAT ACROSS THE WESTERN ADIRONDACKS. EXPECT FRI MAXES TO REACH THE
30S IN MOST AREAS...EXCEPT AROUND OR INTO THE LOWER 40S WITHIN THE
VALLEYS...WITH 20S ACROSS HIGHER ELEVATIONS. COLDER AIR BEHIND THE
FRONT WILL MOVE IN FOR FRI NT AND SAT...WITH FRI NT MINS IN THE
TEENS AND LOWER 20S...AND SAT MAXES MAINLY IN THE 30S WITHIN
VALLEYS...AND 20S ACROSS HIGHER ELEVATIONS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THIS PERIOD WILL BE FAIRLY QUIET AS HIGH PRESSURE BUILDS INTO THE
MID ATLANTIC REGION SATURDAY NIGHT AND DOMINATES OUR WEATHER INTO
THE EARLY PART OF THE COMING WEEK. A CHANCE OF SOME LAKE ENHANCED
SNOW SHOWERS SATURDAY NIGHT...THEN DRY UNTIL TUESDAY NIGHT WHEN A
WEAK BOUNDARY BRINGS ABOUT SOME SNOW AND RAIN SHOWERS WEST OF THE
HUDSON VALLEY WEDNESDAY.
THE PERIOD STARTS OFF CHILLY...LOWS FROM AROUND 10 TO 20 ABOVE ON
SUNDAY MORNING...WITH HIGHS SUNDAY ONLY IN THE UPPER 20S TO THE
MID 30S. TEMPERATURES WILL GRADUALLY MODERATE WITH HIGHS RISING
TO THE UPPER 30S AND LOWER 40S BY TUESDAY AFTERNOON.
FOR THE MOST PART...USED HPC GUIDANCE TO POPULATE THE GRIDS.
&&
.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...
WIDESPREAD IFR CONDITIONS ARE EXPECTED THROUGH AT LEAST
08Z/THU...WITH PERHAPS JUST SOME BRIEF IMPROVEMENTS TO MVFR VSBYS AT
TIMES.
RAIN AND DRIZZLE WILL CONTINUE INTO THIS EVENING...WITH SOME PERIODS
OF MODERATE TO HEAVY RAIN POSSIBLE. THEN...A TRANSITION TO WET SNOW
IS TO OCCUR LATER THIS EVENING...ROUGHLY BETWEEN 01Z-03Z/THU AT KGFL
AND KALB...AND NOT UNTIL AFTER 06Z/THU AT KPOU. THE SNOW MAY BE
MODERATE TO HVY IN INTENSITY...ESP AT KALB AND POSSIBLY KPOU.
PRECIPITATION SHOULD DECREASE IN INTENSITY FROM W TO E BETWEEN
07Z-09Z/THU...AND ENDING BY 11Z/THU IN ALL AREAS.
FOR THU...EXPECT MAINLY VFR CONDITIONS...EXCEPT POSSIBLY SOME MVFR
CIGS/VSBY IN ISOLATED SNOW SHOWERS AT KGFL AND KALB LATER IN THE
AFTERNOON.
WINDS WILL REMAIN FROM THE NORTH TO NORTHEAST AT 5-10 KT THIS
AFTERNOON AND EARLY EVENING...THEN SHIFT INTO THE N...THEN NW AND
INCREASE TO 10-20 KT AFTER 05Z/THU. WINDS WILL THEN BACK INTO THE NW
TO W...AND INCREASE TO 15-25 KT AFTER 14Z/THU...WITH SOME GUSTS
POSSIBLY REACHING 30-35 KT AT KALB.
OUTLOOK...
THU NT-SAT...MAINLY VFR...SLIGHT CHC -SHSN. BREEZY.
SUN-MON...VFR...NO SIG WX.
&&
.HYDROLOGY...
A SIGNIFICANT MIXED PRECIPITATION EVENT WAS OCCURRING ACROSS THE
REGION WITH STORM TOTAL LIQUID AMOUNTS FROM LESS THAN A QUARTER
INCH IN NORTHERN HERKIMER COUNTY TO A LITTLE OVER TWO INCHES IN
THE LOWER HUDSON VALLEY OF NEW YORK AND THE LITCHFIELD HILLS OF
CONNECTICUT. OVER COOLER REGIONS SUCH AS THE HIGHER ELEVATIONS OF
THE CATSKILLS...BERKSHIRES...AND GREEN MOUNTAINS OF SOUTHERN
VERMONT A SUBSTANTIAL AMOUNT OF THIS PRECIPITATION IS FORECAST
TO COME AS SNOW. ACROSS OUR SOUTHERNMOST COUNTIES...EASTERN ULSTER
...DUTCHESS...AND LITCHFIELD...MOST OF THE PRECIPITATION WILL
COME AS RAIN AND LOCALLY HEAVY AMOUNTS MAY AMOUNT TO ENOUGH TO
RESULT IN SOME MINOR FLOODING OF ROADS AND PARKING AREAS AND
CAUSE RISES OF SEVERAL FEET ON RIVERS AND STREAMS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...FLOOD WATCH THROUGH THURSDAY MORNING FOR CTZ001-013.
NY...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR NYZ047-051-
054-058-063.
WINTER WEATHER ADVISORY UNTIL 6 AM EST THURSDAY FOR NYZ039>043-
048>050-052-053-059>061-082>084.
FLOOD WATCH THROUGH THURSDAY MORNING FOR NYZ064>066.
MA...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR MAZ001-025.
VT...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR VTZ013-014.
WINTER WEATHER ADVISORY UNTIL 6 AM EST THURSDAY FOR VTZ015.
&&
$$
SYNOPSIS...11
NEAR TERM...11
SHORT TERM...KL
LONG TERM...RCK
AVIATION...KL
HYDROLOGY...RCK
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
602 PM EST WED DEC 07 2011
...Updated Aviation Discussion...
.Short Term (Tonight and Thursday)...
First off, snow band was not as impressive as the HRRR earlier today
made it out to be. County officials in our Lake Cumberland region
have all indicated very little snow stuck. Webcams from that area
also look mostly just wet and not white. Had some pictures with snow
from the LEX-area webcams in a brief band that went through their in
the last couple of hours, but likewise nothing has accumulated.
Surface temperatures are just too warm, in the mid 30s along with
the still wet grounds from the rain earlier in the week.
Sunshine is poking out some in cloud cover west of a KLEX to
Scottsville line. With any heating though, additional low clouds are
developing. These clouds may yet produce some scattered very light
flurries across central KY, but temperatures will not be cool enough
where these clouds are to promote lots of snow. With the cloud
cover, temperatures are holding to around 40 degrees at most.
Skies should clear out overnight as deep dry air moves into the
region. High pressure will move in south of the region, so expect a
general westerly wind through the night. Expect temperatures to fall
into the 20s areawide overnight under these clear skies. Sheltered
locations may see the low 20s.
High pressure will be centered over the Appalachians during the day
Thursday. Thus expect a southwesterly flow. Clear skies should allow
us to reach the low/mid 40s areawide, roughly 5 degrees below normal.
.Long term (Thursday night - Wednesday)...
A digging shortwave will dive from the northern plains into the
lower Great Lakes on Friday. Moisture return ahead of this system
will be limited and therefore continued to only mention flurries in
the forecast early Friday morning across southern Indiana, gradually
working eastward across north central Kentucky and the Bluegrass
through the day. Temperatures ahead of the front will likely warm
enough for just sprinkles in the late morning and afternoon. In the
morning and the evening, moisture to about 700 mb should yield
some potential for ice crystals as temps at this level will be
around -10 C. No impacts from these flurries are anticipated.
Otherwise, cold frontal boundary moves through Friday afternoon and
evening with a cold airmass lurking for the weekend. Lows Friday
night are expected to drop into the lower 20 in most spots, with a
few upper teens possible across southern Indiana and perhaps the
Bluegrass. High temperatures on Saturday will struggle, only making
it to the low and mid 30s. Saturday night will bring more
temperatures right around the 20 degree mark.
Sunday into the middle of next week, mid level flow will gradually
transition from a progressive zonal flow then try to head back toward
the classic La Nina pattern we have been seeing which would yield
southwest flow aloft with a ridge to our southeast and a developing
trough over the western CONUS. Will keep forecast through Wednesday
dry, although some signs point to another potent system tracking
into the region possibly Thursday or Friday. Although this is pretty
far out, confidence in the recent pattern supported by
teleconnections could lead to another substantial precipitation
event across the Ohio Valley. Stay tuned.
Highs through the first half of next week will gradually moderate
toward the mid 40s, with upper 40s and low 50s ahead of the next
system possible on Wednesday. Lows each night will be in the 20s,
warming to the low 30s by Wednesday morning.
&&
.Aviation (00Z TAF Issuance)...
Expect VFR conditions through the TAF period as our latest weather
system departs the region to the east. Skies will continue to clear
from west to east overnight. Additionally, dry air is filtering into
the area. The T/Td spread should be large enough to limit fog
formation overnight. Current guidance and trends in the observations
are illustrating this as well. Surface winds will become
southwesterly by morning as surface high pressure builds across the
Appalachians.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......RJS
Long Term........BJS
Aviation.........MJP
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
229 PM EST WED DEC 07 2011
.Short Term (Tonight and Thursday)...
First off, snow band was not as impressive as the HRRR earlier today
made it out to be. County officials in our Lake Cumberland region
have all indicated very little snow stuck. Webcams from that area
also look mostly just wet and not white. Had some pictures with snow
from the LEX-area webcams in a brief band that went through their in
the last couple of hours, but likewise nothing has accumulated.
Surface temperatures are just too warm, in the mid 30s along with
the still wet grounds from the rain earlier in the week.
Sunshine is poking out some in cloud cover west of a KLEX to
Scottsville line. With any heating though, additional low clouds are
developing. These clouds may yet produce some scattered very light
flurries across central KY, but temperatures will not be cool enough
where these clouds are to promote lots of snow. With the cloud
cover, temperatures are holding to around 40 degrees at most.
Skies should clear out overnight as deep dry air moves into the
region. High pressure will move in south of the region, so expect a
general westerly wind through the night. Expect temperatures to fall
into the 20s areawide overnight under these clear skies. Sheltered
locations may see the low 20s.
High pressure will be centered over the Appalachians during the day
Thursday. Thus expect a southwesterly flow. Clear skies should allow
us to reach the low/mid 40s areawide, roughly 5 degrees below normal.
.Long term (Thursday night - Wednesday)...
A digging shortwave will dive from the northern plains into the
lower Great Lakes on Friday. Moisture return ahead of this system
will be limited and therefore continued to only mention flurries in
the forecast early Friday morning across southern Indiana, gradually
working eastward across north central Kentucky and the Bluegrass
through the day. Temperatures ahead of the front will likely warm
enough for just sprinkles in the late morning and afternoon. In the
morning and the evening, moisture to about 700 mb should yield
some potential for ice crystals as temps at this level will be
around -10 C. No impacts from these flurries are anticipated.
Otherwise, cold frontal boundary moves through Friday afternoon and
evening with a cold airmass lurking for the weekend. Lows Friday
night are expected to drop into the lower 20 in most spots, with a
few upper teens possible across southern Indiana and perhaps the
Bluegrass. High temperatures on Saturday will struggle, only making
it to the low and mid 30s. Saturday night will bring more
temperatures right around the 20 degree mark.
Sunday into the middle of next week, mid level flow will gradually
transition from a progressive zonal flow then try to head back toward
the classic La Nina pattern we have been seeing which would yield
southwest flow aloft with a ridge to our southeast and a developing
trough over the western CONUS. Will keep forecast through Wednesday
dry, although some signs point to another potent system tracking
into the region possibly Thursday or Friday. Although this is pretty
far out, confidence in the recent pattern supported by
teleconnections could lead to another substantial precipitation
event across the Ohio Valley. Stay tuned.
Highs through the first half of next week will gradually moderate
toward the mid 40s, with upper 40s and low 50s ahead of the next
system possible on Wednesday. Lows each night will be in the 20s,
warming to the low 30s by Wednesday morning.
&&
.Aviation (18Z TAF Issuance)...
Looks like the best band of precip is setting up just east of all of
the TAF sites early this afternoon. 18Z package will go out with
some light showers in the vicinity of KLEX for a few more hours.
Expect MVFR-level clouds to stick around KBWG to mid afternoon and
over KLEX into the evening hours. After that skies will clear
quickly, and expect VFR conditions rest of period. Winds will start
off just west of northerly and then become more westerly by this
evening, as low pressure currently over the Appalachians shifts
eastward farther away from the area.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......RJS
Long Term........BJS
Aviation.........RJS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
308 PM EST WED DEC 7 2011
.SYNOPSIS...
STRENGTHENING LOW PRESSURE, MOVING NORTHEASTWARD PAST THE VIRGINIA COAST,
HAS DRAWN COLDER AIR INTO THE UPPER OHIO VALLEY TO CAUSE A CHANGE
TO SNOW. SOME MOUNTAIN LOCATIONS CAN GET HEAVY SNOW AMOUNTS. HIGH
PRESSURE WILL FOLLOW WITH DRY, BRISK CONDITIONS THURSDAY. AN
EASTBOUND COLD FRONT THROUGH THE GREAT LAKES WILL PROVIDE
SCATTERED SNOW SHOWERS FRIDAY NIGHT.
&&
.NEAR TERM /THROUGH THURSDAY/...
HAVE CONTINUE TO MAKE ADJUSTMENTS TO PRECIPITATION TYPE AND
DURATION AND TEMPERATURES BASED ON RECENT TRENDS IN SURFACE AND
RADAR DATA ALONG WITH RECENT HRRR AND NAM MODEL OUTPUT.
EXPECT ALL THE PRECIPITATION TO BE SNOW BY 3 TO 4 PM. BASED ON NAM
MODEL PROFILES, SHOWING STRONG UPDRAFTS WITHIN THE DENDRITIC SNOW
GROWTH ZONE AROUND -15C, STILL EXPECT A BURST OF HEAVIER SNOW
ACROSS THE MOUNTAINS THIS EVENING. HENCE HAVE MAINTAINED THE
WINTER STORM WARNINGS AND ADVISORIES FOR THE MOUNTAIN AREAS WITH
SNOW AMOUNTS UPWARDS OF 4 INCHES.
STILL THINK THE SNOWFALL WILL CUTOFF GENERALLY BY 2 AM FOR THE
RIDGES. HAVE WIND GUSTS TO 30 MPH PER NAM MODEL PROFILES.
DUE TO DROPPING TEMPERATURES TONIGHT, FOR ALL LOCATIONS, REGARDLESS
OF SNOW AMOUNTS, THERE IS THE HAZARD OF WET UNTREATED PAVEMENTS
TURNING ICY. LOWS TONIGHT IN THE LOWER TO MID 20S.
ENSUING HIGH PRESSURE SHOULD PROVIDE ALL LOCATIONS WITH DRY, BRISK
CONDITIONS THURSDAY.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
MAINLY DRY AND COLD CONDITIONS WILL PREVAIL THURSDAY NIGHT.
THE NEXT FRONT IS PROGGED TO AFFECT THE REGION FRIDAY AND
FRIDAY NIGHT. MOST MODELS IN AGREEMENT KEEPING THE GREATEST
FORCING AND MOISTURE FROM THE I-80 CORRIDOR NORTHWARD. WILL
INCREASE POPS TO LIKELY THERE LATE FRIDAY INTO FRIDAY NIGHT
WITH CHANCE POPS FOR WESTERN PA...WITH LESSER CHANCES ACROSS
EASTERN OHIO. THERMAL PROFILES WILL BE COLD ENOUGH FOR A MAINLY
SNOW EVENT.
SUB ADVISORY LEVEL SNOW ACCUMULATIONS ARE POSSIBLE FOR THE I-80
CORRIDOR...WITH MINOR ACCUMULATIONS FOR THE RIDGES AND LITTLE
ACCUMULATION ELSEWHERE. THE SYSTEM WILL EXIT THE REGION BY
SATURDAY FOR DRY AND COLD CONDITIONS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
HIGH PRESSURE WILL DOMINATE THE FIRST HALF OF THE PERIOD WITH
TEMPERATURES BELOW NORMAL...MODERATING A FEW DEGREES EACH DAY AS THE
FLOW BECOMES MORE SOUTHERLY.
MORE UNCERTAINTY LIES IN THE LATER PART OF THE PERIOD AS THE
DETERMINISTIC MODELS HANDLE THE DEVELOPMENT OF THE NEXT SYSTEM
DIFFERENTLY FOR WEDNESDAY AND THURSDAY.
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
EXPECT AREAS OF IFR IN SNOW AND FOG INTO 03Z. CONDITIONS SHOULD
IMPROVE...FIRST AT ZZV AND FKL WHERE CIGS HAVE ALREADY LIFTED TO
MVFR...AND LAST AT MGW AND LBE SINCE THE WRAP-AROUND MOISTURE
ASSOCIATED WITH THE LOW WILL BE LAST TO LEAVE THESE PORTS.
SKIES SHOULD SCATTER OUT OVERNIGHT BUT WITH NORTHWEST FLOW ALOFT
SCATTERED TO BROKEN CU SHOULD REDEVELOP ON THURSDAY. THINK AT THIS
POINT THAT CONDITIONS WILL REMAIN VFR DURING THE DAY THURSDAY BUT
WITH ENHANCEMENT FRONT THE LAKE...MVFR CIGS MAY CAUSE TEMPORARY
IMPACTS ESPECIALLY FOR THE NORTHERN PORTS.
OUTLOOK...THURSDAY NIGHT THROUGH MONDAY...
GENERALLY VFR THROUGH MONDAY WITH POSSIBLE RESTRICTIONS IN SNOW WITH
THE SHORTWAVE PASSAGE FRIDAY NIGHT/SATURDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING UNTIL 4 AM EST THURSDAY FOR MDZ001.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL 4 AM EST THURSDAY FOR PAZ023-031-
073-075.
WINTER STORM WARNING UNTIL 4 AM EST THURSDAY FOR PAZ074-076.
WV...WINTER WEATHER ADVISORY UNTIL 4 AM EST THURSDAY FOR WVZ021-022.
WINTER STORM WARNING UNTIL 4 AM EST THURSDAY FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1142 AM EST WED DEC 7 2011
.SYNOPSIS...
STRENGTHENING LOW PRESSURE, MOVING NORTHEASTWARD THROUGH VIRGINIA,
WILL DRAW COLDER AIR INTO THE UPPER OHIO VALLEY AND CHANGE ANY
REMAINING RAIN TO WET SNOW BY TONIGHT. SOME MOUNTAIN LOCATIONS CAN
GET HEAVY SNOW AMOUNTS. HIGH PRESSURE WILL PROVIDE DRY, BRISK
CONDITIONS THURSDAY.
&&
.NEAR TERM /THROUGH THURSDAY/...
MADE ADJUSTMENTS TO DURATION OF PRECIPITATION AND TIMING OF CHANGE
FROM RAIN TO SNOW BASED ON BLEND OF RECENT SURFACE AND RADAR DATA
AND HRRR AND NAM MODEL OUTPUT. HAVE GOTTEN SOME REPORTS OF WET
SNOW STARTING OVER THE HIGHER MOUNTAINS. HAVE CONCERNS HOW LONG
THE PRECIPITATION WILL HANG ON TO AREAS WEST OF THE RIDGES THIS
EVENING. DYNAMICS STILL VERY FAVORABLE FOR A BURST OF HEAVY WET
SNOW ACROSS THE MOUNTAINS THIS EVENING.
SO FOR NOW HAVE LARGELY MAINTAINED THE FORECASTED SNOW AMOUNTS.
DID CUT OFF END OF THE SNOWFALL GENERALLY BY 2 AM FOR THE RIDGES.
HAVE WIND GUSTS TO 30 MPH PER NAM MODEL PROFILES.
DUE TO DROPPING TEMPERATURES TONIGHT, FOR ALL LOCATIONS, REGARDLESS
OF SNOW AMOUNTS, THERE IS THE HAZARD OF WET UNTREATED PAVEMENTS
TURNING ICY. LOWS TONIGHT IN THE LOWER TO MID 20S.
ENSUING HIGH PRESSURE SHOULD PROVIDE ALL LOCATIONS WITH DRY, BRISK
CONDITIONS THURSDAY.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
COLD WEST WINDS ACROSS THE LAKE ERIE MAY CAUSE A FEW SNOW SHOWERS
ACROSS THE I-80 CORRIDOR THURSDAY OTHERWISE DRY AND COLD.
HIGH PRESSURE SHOULD PROVIDE DRY AND COLD CONDITIONS THURSDAY
NIGHT. NEXT COLD FRONT APPROACHES WITH A CHANCE FOR SNOW SHOWERS
LATER FRIDAY INTO FRIDAY NIGHT. TEMPERATURES WILL BE BELOW NORMAL
THROUGH THE PERIOD.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
COLD NORTHWEST FLOW WILL BE REINFORCED BEHIND COLD FRONT AND BRING
SOME SNOW SHOWERS NORTH AND RIDGES SATURDAY BEFORE HIGH PRESSURE
BUILDS IN ENDING PRECIP SATURDAY NIGHT.
COLD RIDGE OF HIGH PRESSURE WILL DOMINATE REMAINDER OF WEEKEND
WITH MODERATING TEMPERATURES EARLY NEXT WEEK.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
DIFFICULT AND LOW CONFIDENCE FORECAST THROUGH TONIGHT. WILL
CONTINUE WITH A FORECAST OF IFR TO LIFR CIGS THROUGH THIS MORNING.
THERE SHOULD BE A SLOW IMPROVEMENT TO MVFR FROM PIT NORTH THIS
AFTERNOON. RAIN WILL CONTINUE TO MOVE ACROSS THE SOUTHERN HALF OF
THE REGION THIS MORNING. RAIN WILL LIKELY CHANGE TO SNOW FROM
WEST TO EAST DURING THE LATE MORNING/AFTERNOON. FKL WILL BE FAR
ENOUGH TO THE NORTH TO MISS THE PRECIP. TIMING THE CHANGE OVER TO
SNOW WILL BE DIFFICULT AS THE COLDER AIR WILL TAKE ITS TIME MOVING
SOUTHWARD. EXPECT ALL PORTS TO CHANGE TO SNOW BY LATE AFT. THE
GREATEST EFFECT FROM THE SNOW WILL LIKELY BE FELT AT LBE AND MGW
AND THESE PORTS WILL REQUIRE LOWER RESTRICTIONS IN VIS TODAY.
OUTLOOK...WEDNESDAY NIGHT THROUGH SUNDAY...
MVFR RESTRICTIONS MAY LINGER INTO WEDNESDAY NIGHT BEFORE HIGH
PRESSURE BUILDS IN FOR THURSDAY AND FRIDAY. NEXT CHANCE FOR
RESTRICTIONS WILL BE WITH THE SHORTWAVE PASSAGE SATURDAY. VFR WILL
RETURN SUNDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING UNTIL 4 AM EST THURSDAY FOR MDZ001.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL 4 AM EST THURSDAY FOR PAZ023-031-
073-075.
WINTER STORM WARNING UNTIL 4 AM EST THURSDAY FOR PAZ074-076.
WV...WINTER WEATHER ADVISORY UNTIL 4 AM EST THURSDAY FOR WVZ021-022.
WINTER STORM WARNING UNTIL 4 AM EST THURSDAY FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
354 PM EST WED DEC 7 2011
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED CYCLONIC MID/UPPER LEVEL FLOW
AROUND A VORTEX OVER HUDSON BAY BRINGING NRN STREAM WNW FLOW FROM
SRN CANADA INTO THE UPPER GREAT LAKES. AN UPSTREAM SHORTWAVE TROUGH WAS
MOVING THROUGH SRN MANITOBA WITH ANOTHER TRAILING SHRTWV OVER NRN
SASK. AT THE SFC...WINDS WERE VEERING W TO WNW BEHIND A TROUGH/FRONT
THAT MOVED THROUGH THIS MORNING. A TRAILING ARCTIC FRONT NEAR LAKE
WINNIPEG WAS DROPPING TOWARD THE AREA WITH MUCH COLDER AIR BEHIND IT
WITH TEMPERATURES FROM -5 TO 5F OVER NORTHERN MANITOBA/SASK. VIS
LOOP INDICATED CLEARING SKIES OVER THE WEST HALF OF THE CWA AS DRIER
AIR MOVES INTO THE REGION. EVEN WITH 850 MB TEMPS AROUND
-11C...SKIES HAD CLEARED OVER MUCH OF WRN LAKE SUPERIOR.
&&
.SHORT TERM...TONIGHT AND THURSDAY
CLOUDS AND SCT LIGHT LAKE EFFECT SNOW SHOWERS ARE EXPECTED TO
REDEVELOP OVER WRN LAKE SUPERIOR INTO WRN UPPER MI THIS EVENING AS
GREATER LOW LEVEL MOISTURE MOVES TOWARD THE AREA...PER VIS LOOP.
PASSAGE OF THE SASK SHRTWV AND ARCTIC FRONT THU MORNING WITH
INCREASING 850-700 MB MOISTURE AND INVERSION HEIGHTS CLIMBING AROUND
8K FT WILL PROVIDE A SIGNIFICANT BOOST TO THE LAKE EFFECT SNOW. SNOW
GROWTH ALSO LOOKS FAVORABLE AS THE DGZ WILL BE RIGHT IN THE BEST
OMEGA/UPWARD MOTION. GIVEN MODEL QPF AND SNOW/WATER RATIOS
APPROACHING 30/1 WOULD NOT BE SURPRISED TO SEE PERIODS OF MODERATE
TO HEAVY SNOWFALL. THE MOST PERSISTENT LOW LEVEL CONV AND CHANCE FOR
GREATEST ACCUMULATION IS EXPECTED FROM FAR NE ONTONAGON COUNTY INTO
CENTRAL HOUGHTON COUNTY...FROM GREENLAND TO TWIN LAKES. INCREASINGLY
CONVERGENT WRLY FLOW. INCREASING WINDS GUSTING TO NEAR 30 MPH AT
TIMES ON THURSDAY WILL ALSO SHARPLY REDUCE VSBYS IN BLOWING SNOW AS
WELL AND CAUSE DRIFTING SNOW ACROSS THE ROADS. SO...WITH THE
LIKELIHOOD OF AN EXTENDED PERIOD OF LES...HEAVY SNOW AT TIMES...A
LAKE EFFECT SNOW WARNING WAS ISSUED. CONFIDENCE IN ACCUMULATIONS BY
LATE THURSDAY IS LIMITED BY UNCERTAINTY ON WHERE THE HEAVIER BANDS
WILL DEVELOP AND HOW LONG THEY WILL PERSIST. SNOWFALL GENERALLY FROM
3 TO 7 INCHES IS LIKELY WITH SOME HIGHER LCL AMOUNTS.
LOCATIONS NEAR LAKE SUPERIOR EAST OF MUNISING...FROM GRAND MARAIS TO
TWO HEART MAY ALSO SEE A PERIOD OF HEAVIER LES IF THE EXPECTED
DOMINANT BAND SAGS SOUTHWARD WITH SLIGHTLY VEERING WINDS THU.
UNCERTAINTY REMAINS WHETHER THE HEAVIER SNOW WILL REMAIN OFFSHORE OR
MOVE INLAND...SO NO HEADLINES WERE ISSUED AT THIS TIME.
.LONG TERM /THURSDAY NIGHT THROUGH NEXT WEDNESDAY/...
SIGNIFICANT LAKE EFFECT SNOW IS THE MAIN CONCERN FOR THE INITIAL
PORTION OF THE LONG TERM.
LARGE SCALE TROUGH WITH COLDEST AIR OF SEASON THUS FAR TO PUSH INTO
THE AREA SETTLES OVER MUCH OF THE EASTERN CONUS TO END THE WEEK.
NOT MUCH IN THE WAY OF LARGER SCALE SHORTWAVES THAT WILL BRING
WIDESPREAD SNOW TO THE AREA...BUT SIGNIFICANT LK EFFECT FOR WEST
FLOW AREAS IS LIKELY AS H85 TEMPS TUMBLE TO AROUND -18C BY FRIDAY.
MODEL SOUNDINGS INDICATE LAKE INDUCED CAPES AOA 600J/KG WHILE LAKE
EQUIBRIUM LEVELS ARE OVR 10 KFT AGL. HIGHER OVERWATER INSTABILITY
IS SUPPLEMENTED BY STRONG LOW-LEVEL (SFC-H95) CONVERGENCE.
MODELS ARE ACTUALLY IN VERY GOOD AGREEMENT WITH OVERALL SCENARIO
THOUGH SUBTLE SHIFTS IN BLYR WINDS MAKE ALL THE DIFFERENCE AS TO
THE LOCATIONS THAT END UP WITH THE HIGHEST SNOW AMOUNTS. BY LATE
THURSDAY AND INTO THURSDAY NIGHT...SHEAR WITHIN THE SFC-H8 LAYER
IS QUITE LOW...LEADING TO BETTER CHANCE THAT DOMINANT BANDS CAN
ORGANIZE. WINDS BECOMING WESTERLY AT 925MB WITH WSW OR SW SFC WINDS
OVR UPR MI (ENHANCED BY NIGHTTIME LAND BREEZES) WOULD FAVOR STRONGEST
CONVERGENCE/HEAVIER SNOW BANDS OVR WESTERN UPR MI FM ONTONAGON
THROUGH TWIN LAKES/PAINESDALE. WARNING WILL CONTINUE FOR THOSE AREAS
THROUGH LATE FRIDAY FOR THIS PROLONGED HEAVY LAKE EFFECT SNOW EVENT.
STORM TOTALS OVER A FOOT SEEM PRETTY LIKELY IF THE PRIMARY SNOW BAND
STAYS STATIONARY FOR REASONABLE AMOUNT OF TIME.
HIGHER TERRAIN AREAS OF REST OF HOUGHTON COUNTY WILL ALSO SEE
OFF-AND-ON HEAVIER SNOW SHOWERS. ALSO EXPECT SOME HEAVIER SNOW TO
OCCUR OVR SOUTHERN PORTIONS OF HOUGHTON COUNTY...MAINLY NORTH OF
M-38. ADVY WILL COVER THIS POSSIBILITY. EXPECT VERY LITTLE IF ANY
SNOW TOWARD KENTON/SIDNAW ALONG M-28. KEWEENAW COUNTY IS MORE OF A
QUESTION MARK AS THE MORE WNW BLYR WINDS THERE ARE NOT AS FAVORABLE.
STILL THOUGH...DEGREE OF INSTABILITY AND SUFFICIENT MOISTURE PRESENT
COULD LEAD TO LOCALIZED HEAVY AMOUNTS OVR HIGHER TERRAIN THERE AS
WELL. AN ADVISORY WILL HANDLE THIS FOR NOW...THOUGH LATER UPGRADE
COULD BE NEEDED. EXPECT QUIET WEATHER FOR REST OF THE CWA THURSDAY
NIGHT INTO FRIDAY. TEMPS WILL BE ON THE CHILLY SIDE THOUGH WITH
NIGHTTIME LOWS THURSDAY NIGHT TOWARD THE ZERO MARK OVR INTERIOR SW
UPR MI AND HIGHS ON FRIDAY MAINLY STAYING IN THE TEENS.
BY LATE FRIDAY...WEAKER TROUGH FCST TO SLIDE THROUGH THE AREA MAY
VEER WINDS TO MORE NW LEADING TO INCREASED CHANCES OF LAKE EFFECT
SNOW SHOWERS INTO FAR EASTERN SECTION OF CWA...MAINLY EAST OF
MUNISING AND WELL NORTH OF NEWBERRY. LAKE EFFECT SNOW PARAMETER
DEVELOPED BY NWS GAYLORD WHICH INCORPORATES 1000-850MB
SHEAR/850-700MB RH/H85 TEMPS INDICATES FAVORABLE SETUP FOR HEAVY
SNOW RATES IN THOSE EASTERN AREAS FRIDAY AFTN/FRIDAY EVENING.
SNOWFALL RATES UP TO 2 INCHES PER HOUR COULD OCCUR IN THOSE AREAS
AND HEADLINES MAY BE NEEDED AT SOME POINT. HOWEVER...WILL LEAVE
THOSE DECISIONS TO LATER SHIFTS AS EXPECT VERY LITTLE SNOWFALL IN
THOSE AREAS THROUGH FRIDAY MORNING.
TROUGH AND COLDER AIR SFC-H85 SLOWLY HEAD INTO LOWER GREAT LAKES
FRIDAY NIGHT INTO SATURDAY. WARM AIR ADVECTION STARTS UP BY SATURDAY
LEADING TO A PUSH OF ISENTROPIC ASCENT 285-290K (750-650MB) ACROSS
MUCH OF THE CWA. UVM IN THE LAYER FAIRLY STRONG...BUT TROUBLE IS
THERE IS DRY AIR LINGERING BLO H85 THRU THE DAY. COULD BE SOME
FLURRIES OR LIGHT SNOW SHOWERS...BUT BETTER SATURATION WILL KEEP THE
GREATER CHANCE OF ACCUMULATING SNOWS MORE INTO ONTARIO. GUSTY SW
WINDS WILL ADD CHILL TO THE AIR DESPITE SFC TEMPS REBOUNDING INTO
LOWER TO MIDDLE 20S.
FOR THE EXTENDED...TROUGH THAT WAS OVER THE AREA FOR MUCH OF THIS
WEEK IS FCST TO EASE INTO EASTERN CANADA LEADING TO MORE OF A ZONAL
FLOW PATTERN/WARMING TREND BY EARLY NEXT WEEK. WEAK SHORTWAVE/WARM
FRONT SLIDES ACROSS UPR LAKES MONDAY BUT MOISTURE IS MINIMAL SO DO
NOT EXPECT A WHOLE LOT OF PRECIPITIATON. BETTER CHANCE OF
PRECIPITATION WOULD BE FARTHER NORTH CLOSER TO H85-H7 FRONTOGENESIS
AND RIGHT ENTRANCE REGION OF UPR JET OVR ONTARIO. ANOTHER TROUGH
FORMING OVR SCNTRL CANADA IS FCST TO MOVE ACROSS THE UPR GREAT LAKES
LATE TUESDAY INTO WEDNESDAY. DIFFERENCES BEGIN TO APPEAR WITH REGARD
TO DEPTH OF TROUGH BY WEDNESDAY. LAST TWO RUNS OF GFS CLOSED THE
TROUGH OFF OVR UPR MISSISSIPPI RIVER VALLEY/UPR LAKES. MEANWHILE...
RECENT RUNS OF THE ECMWF AND PREVIOUS RUNS OF GFS INDICATED MORE OF
A PROGRESSIVE SYSTEM...WITH DEEPER SYSTEM FORMING OVR CNTRL PLAINS
MID-LATE NEXT WEEK. ENSEMBLES FM GFS/ECMWF/CANADIAN SHED LITTLE
LIGHT ON THE SUBJECT WITH MIXED SIGNALS IN TERMS OF STRENGTH AND
MOVEMENT OF THE TROUGHS. DOES SEEM THAT AT LEAST ECMWF WOULD SUPPORT
BETTER CHANCE OF ORGANIZED PRECIPITATION IN THE MIDWEEK TIME FRAME.
WILL NOT PUT TOO MUCH EMPHASIS ON THIS YET THOUGH AS SUPPORT FOR
THAT IDEA REMAINS LIMITED SUPPORT LOOKING AT OTHER AVILABLE GUIDANCE
AND ENSEMBLES.
&&
.AVIATION /FOR THE 18Z TAF ISSUANCE/
DRIER AIR MOVING IN ON WESTERLY WINDS BEHIND A TROUGH WILL BRING
IMPROVING CONDITIONS FOR KIWD/KSAW TO VFR BY LATE THIS AFTERNOON.
HOWEVER...KCMX IS EXPECTED TO RETAIN MVFR CIGS THIS AFTERNOON WITH
LAKE MOISTURE CONTRIBUTION AND UPSLOPE WNW FLOW. AS COLDER ARCTIC
AIR MOVES INTO THE REGION LATE TONIGHT...LAKE EFFECT SNOW SHOWERS
WILL INCREASE ACROSS THE KEWEENAW. HOWEVER...THE LOWER END VSBY WITH
SHSN...DOWN TO AROUND 1SM SHOULD HOLD OFF UNTIL AROUND 12Z/THU. THE
WEST WINDS WILL NOT BE FAVORABLE FOR ANY LES AT KSAW/KIWD...BUT LOW
LEVEL MOISTURE IN THE COLD AIRMASS WILL SUPPORT MVFR CIGS.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
WINDS MAINLY OUT OF A WESTERLY DIRECTION OVER 20KTS WILL PREVAIL THROUGH
MUCH OF THE PERIOD. THE WINDS/WAVES ALONG WITH PLENTY OF COLD AIR
WILL RESULT IN THE POTENTIAL FOR FREEZING SPRAY TONIGHT INTO FRIDAY.
WESTERLY GALES ARE EXPECTED TO RETURN AROUND SUNRISE THURSDAY BEHIND
AN ARCTIC FRONT OVER THE WEST HALF...BEFORE EXTENDING THROUGH CENTRAL AND
EASTERN LS THROUGH EARLY THURSDAY EVENING.
EXPECT STRONG HIGH PRESSURE ACROSS SW CANADA TO WEAKEN ACROSS THE
PLAINS STATES FRIDAY...WHILE EXTENDING A RIDGE ACROSS LS BY FRIDAY
NIGHT. LOW PRESSURE OVER MANITOBA SATURDAY MORNING WILL SLIDE ACROSS
ONTARIO SATURDAY AFTERNOON AND EVENING...WHILE DRAGGING A TROUGH
OVER LS. A PERIOD OF SW GALES IS POSSIBLE SATURDAY AHEAD OF THE LOW.
ANOTHER LOW PRESSURE SYSTEM...OVER THE DAKOTAS SUNDAY MORNING...WILL
LIKELY FILTER ACROSS LAKE SUPERIOR SUNDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING FROM 1 AM THURSDAY TO 7 PM EST FRIDAY
FOR MIZ002-003.
LAKE EFFECT SNOW ADVISORY FROM 1 AM THURSDAY TO 7 PM EST FRIDAY
FOR MIZ001-084.
LAKE SUPERIOR...
GALE WARNING FROM 7 AM THURSDAY TO 1 AM EST FRIDAY FOR
LSZ263>267.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...JLB
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1245 PM EST WED DEC 7 2011
UPDATED AVIATION DISCUSSION FOR 12Z TAFS
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS REVEAL AN ACTIVE NRN STREAM FLOW TAKING
SHAPE OVER WRN AND CENTRAL CANADA INTO THE NRN CONUS. ONE SHORTWAVE
MOVING THROUGH NRN ONTARIO AND THE NRN PLAINS WILL CONTINUE EAST
ACROSS THE UPR GREAT LAKES PUSHING A COLD FRONT ACROSS THE REGION
TODAY. A SECOND CLIPPER SHORTWAVE MOVING THROUGH ALBERTA IS
EXPECTED TO MOVE ACROSS THE UPPER GREAT LAKES LATE TONIGHT INTO
THURSDAY USHERING IN THE COLDEST AIR OF THE SEASON AND SETTING UP A
PROLONGED LAKE EFFECT SNOW EVENT FOR NORTHWEST UPPER MI AND POSSIBLY
SHORELINE AREAS FROM GRAND MARAIS EAST TO WHITEFISH POINT.
&&
.DISCUSSION...
MAIN FCST CONCERN IS LES POTENTIAL WITH THE FRONT/TROUGH MOVING
THROUGH THE AREA TODAY AND THEN SECONDARY CLIPPER SYSTEM/ARCTIC PUSH
MOVING THROUGH LATE TONIGHT INTO THURSDAY.
TODAY...SATELLITE TRENDS AND MODEL RH/Q-VECT CONV FIELDS SUGGEST
LOWER CLOUDS OVER WESTERN UPPER MI WILL CONTINUE TO SPREAD EAST
ACROSS THE REST OF THE FCST AREA LATER THIS MORNING. COMBINATION OF
LOW-LVL CONV AND MODERATE Q-VECT CONV ALONG INCOMING COLD FRONT AND
CAA BEHIND THE FRONT SHOULD BRING SOME LIGHT SNOW TO NRN SECTIONS OF
FCST AREA TODAY. LOOK FOR ANY LES ACCUMS GENERALLY LESS THAN AN
INCH.
PASSAGE OF CLIPPER SHORTWAVE LATE TONIGHT SHOULD PROVIDE A BRIEF
PERIOD OF ENHANCEMENT TO LES ACCUMS LATE TONIGHT INTO THURSDAY
MORNING AS 850 MB TEMPS LOWER TO AROUND -15C BY 12Z WED. SNOW GROWTH
ALSO LOOKS FAVORABLE AS THE DGZ WILL BE RIGHT IN THE BEST
OMEGA/UPWARD MOTION. GIVEN MODEL QPF AND SNOW/WATER RATIOS
APPROACHING 30/1 WOULD NOT BE SURPRISED TO SEE A QUICK 4-7 INCHES OF
LES OVER THE KEWEENAW PENINSULA AND PERHAPS OVER THE LAKE SUPERIOR
SHORELINE EAST OF PICTURED ROCKS WHERE A DOMINANT LES BAND COULD SET
UP IN AN INCREASINGLY CONVERGENT WRLY FLOW. INCREASING WINDS GUSTING
TO NEAR 30 MPH AT TIMES ON THURSDAY WILL ALSO SHARPLY REDUCE VSBYS
IN BLOWING SNOW AS WELL AS CAUSE DRIFTING OF SNOW ACROSS ROADS.
AFTER THE CLIPPER SHORTWAVE MOVES EAST THU MORNING...THE POTENTIAL
FOR HEAVIER LES BCMS LESS CERTAIN...AND THERE WILL LIKELY BE A LULL
IN THE SNOW FOR THU AFTERNOON INTO THU EVENING AS RDDG AND AN INFLUX
OF DRIER AIR FROM WEST OF THE LAKE MAY LIMIT LES ACCUMS.
BECAUSE OF THIS POSSIBLE LULL AND THE UNCERTAINTY OF DETAILS WITH
WHERE THE DOMINANT BAND WOULD SET UP LATE TONIGHT INTO THU MORNING
HAVE DECIDED TO JUST KEEP THE LES WATCH GOING FOR NRN
ONTONAGON...NRN HOUGHTON AND KEWEENAW COUNTIES FOR LATE TONIGHT INTO
FRI NIGHT. HOWEVER...WOULD NOT BE SURPRISED TO SEE A LES WARNING
ISSUED ON THE DAY SHIFT FOR THE ABOVE MENTIONED COUNTIES AND
POSSIBLY AN ADVISORY ISSUED FOR THE ERN ALGER AND NRN LUCE SHORELINE
AREAS.
LES COULD PICK UP AGAIN LATE THU NIGHT INTO FRI MORNING OVER THE
KEWEENAW PENINSULA AS MODELS SHOW THE MID-UPR LVL TROF AXIS MOVING
OVERHEAD PROVIDING ENHANCEMENT TO LES BANDS. 850 MB TEMPS NEAR -20C
AND INCREASED LOW-LVL CONVERGENCE WITH DEVELOPING LAND BREEZES WILL
LIKELY FOCUS ANOTHER DOMINANT LES BAND OVER KEWEENAW PENINSULA.
AGAIN SNOW GROWTH LOOKS PRETTY FAVORABLE AS OMEGA INTERSECTS DGZ.
LAND BREEZES MAY SPARE THE FAR ERN SHORELINE AREAS THE BRUNT OF
HEAVIER SNOW BY PUSHING BAND FAR ENOUGH OFFSHORE.
AS MID-LVL TROF AND DEEPER MOISTURE STARTS TO DEPART THE WESTERN
CWA...EXPECT LES TO BEGIN TO DIMINISH FRI AFTERNOON...BUT THERE WILL
STILL BE AT LEAST SOME ONGOING ACCUMULATION INTO FRI EVENING. WITH
WINDS SHIFTING MORE OUT OF THE WSW...EXPECT BEST BANDS TO BE OVER
THE NRN PORTIONS OF THE KEWEENAW AND OFFSHORE OF THE ERN CWA.
EXPECT LES TO COME TO AN END ON SAT...AS A CLIPPER SYSTEM DROPS
THROUGH SOUTHERN ONTARIO AND SHIFTS WINDS TO THE SW PRODUCING WAA
ALOFT. ANOTEHR CLIPPER SYSTEM AND ASSOC FRONT MAY BRING SOME MORE
MORE LIGHT SNOW TO THE AREA AGAIN ON MONDAY WITH SOME LIGHT LES
POSSIBLE INTO MONDAY NIGHT.
&&
.AVIATION /FOR THE 12Z TAF ISSUANCE/
DRIER AIR MOVING IN ON WESTERLY WINDS BEHIND A TROUGH WILL BRING
IMPROVING CONDITIONS FOR KIWD/KSAW TO VFR BY LATE THIS AFTERNOON.
HOWEVER...KCMX IS EXPECTED TO RETAIN MVFR CIGS THIS AFTERNOON WITH
LAKE MOISTURE CONTRIBUTION AND UPSLOPE WNW FLOW. AS COLDER ARCTIC
AIR MOVES INTO THE REGION LATE TONIGHT...LAKE EFFECT SNOW SHOWERS
WILL INCREASE ACROSS THE KEWEENAW. HOWEVER...THE LOWER END VSBY WITH
SHSN...DOWN TO AROUND 1SM SHOULD HOLD OFF UNTIL AROUND 12Z/THU. THE
WEST WINDS WILL NOT BE FAVORABLE FOR ANY LES AT KSAW/KIWD...BUT LOW
LEVEL MOISTURE IN THE COLD AIRMASS WILL SUPPORT MVFR CIGS.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
WINDS MAINLY OUT OF A WESTERLY DIRECTION OVER 20KTS WILL BE COMMON
THROUGH MUCH OF THE PERIOD...ALONG WITH PLENTY OF COLD AIR WHICH
WILL RESULT IN THE POTENTIAL FOR FREEZING SPRAY TONIGHT INTO FRIDAY.
A TROUGH OF LOW PRESSURE ACROSS LS WILL EXIT EAST TODAY...BRINGING
AN END TO THE SW GALES OVER THE WESTERN HALF OF LS. WESTERLY GALES
MAY RETURN AROUND SUNRISE THURSDAY OVER THE WEST HALF...BEFORE
EXTENDING THROUGH CENTRAL AND EASTERN LS THROUGH EARLY THURSDAY
EVENING.
EXPECT STRONG HIGH PRESSURE ACROSS SW CANADA TO WEAKEN
ACROSS THE PLAINS STATES FRIDAY...WHILE EXTENDING A RIDGE ACROSS LS
BY FRIDAY NIGHT. LOW PRESSURE OVER MANITOBA SATURDAY MORNING WILL
SLIDE ACROSS ONTARIO SATURDAY AFTERNOON AND EVENING...WHILE DRAGGING
A TROUGH OVER LS. ANOTHER LOW PRESSURE SYSTEM...OVER THE DAKOTAS
SUNDAY MORNING...WILL LIKELY FILTER ACROSS LS SUNDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WATCH FROM LATE TONIGHT THROUGH LATE FRIDAY
NIGHT FOR MIZ001>003.
LAKE SUPERIOR...
GALE WARNING UNTIL 10 AM EST THIS MORNING FOR LSZ263-264-266.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...VOSS
DISCUSSION...VOSS
AVIATION...JLB
MARINE...KF
AREA FORECAST DISCUSSION
NWS JACKSON MS
1153 AM CST WED DEC 7 2011
.UPDATE...
THIS AFTERNOON...LATEST VISIBLE IMAGERY TRENDS AND RUC GUIDANCE INDICATE
THAT THE SUBSIDENCE ON THE BACKSIDE OF THE TROUGH IS NOT ENOUGH TO
MIX OUT A MOIST THERMAL TROUGH ALONG THE MS RIVER AND COLD ADVECTION
STRATOCUMULUS ARE REGENERATING...SO HAVE DELAYED THE CLEARING SOME
AND LOWERED HIGHS A BIT BASED ON THESE TRENDS. STILL EXPECT CLEARING
SKIES FOR TONIGHT AS HEIGHTS RISE AND SURFACE HIGH PRESSURE SETTLES
OVER THE AREA.
.PREV DISCUSSION... /ISSUED 1005 AM CST WED DEC 7 2011/
UPDATE...
THE LIGHT SNOW EVENT IS WINDING DOWN QUICKLY AS THE INTENSE MID LEVEL
TROUGH SWINGS EASTWARD ACROSS THE ARKLAMISS. A FEW FLURRIES WILL
CONTINUE OVER THE GOLDEN TRIANGLE REGION LATE THIS MORNING...BUT WILL
GO AHEAD AND CANCEL THE WINTER WEATHER ADVISORY GIVEN NO ADDITIONAL
SNOWFALL ACCUMULATION AND SFC TEMPERATURES ABOVE FREEZING.
THE LATEST VISIBLE SATELLITE IMAGERY INDICATES STRONG SUBSIDENCE ON
THE BACK SIDE OF THE TROUGH IS ERODING THE STRATOCUMULUS DECK AND
EXPECT MOSTLY SUNNY SKIES TO ENVELOP THE FORECAST AREA AS WE GO
THROUGH THE AFTERNOON. THE FORECAST IS GENERALLY ON TRACK AND ONLY
MINOR ADJUSTMENTS ARE NECESSARY. /EC/
PREV DISCUSSION... /ISSUED 321 AM CST WED DEC 7 2011/
FOR TONIGHT...SFC HIGH PRESSURE WILL BUILD OVER THE AREA AND PROVIDE
GREAT RAD COOLING CONDITIONS. LOOK FOR ALL OF THE AREA TO FALL
BETWEEN 20-25 DEGREES. SOME UPPER TEENS ARE NOT OUT OF THE QUESTION
EITHER. WE WILL HAVE TO KEEP AN EYE ON THE POTENTIAL FOR FOG TO
DEVELOP AS BOUNDARY LAYER CONDITIONS LOOK TO SUPPORT SUCH CONDITIONS
AFTER TEMPS FALL AND CROSSOVER AFTERNOON DEWPTS. COOL/COLD CONDITIONS
WILL EXIST FOR THU AND THU NGT AS THE SFC RIDGE WILL STILL BE OVER
THE REGION. /CME/
LONG TERM...FRIDAY THROUGH WEDNESDAY...TEMPERATURES WILL MODERATE A
BIT ON FRIDAY BEFORE ANOTHER REINFORCING DRY COLD FRONT MOVES
THROUGH FRIDAY AFTERNOON WITH HIGHS IN THE MID TO UPPER 50S. ANOTHER
COLD/BREEZY NIGHT IS ON TAP FRIDAY NIGHT WITH LOWS FALLING INTO THE
UPPER 20S. NORTHEAST FLOW AND COLD AIR ADVECTION WILL CONTINUE ON
SATURDAY WITH AFTERNOON HIGHS ONLY CLIMBING TO THE LOW 50S.
BEYOND SATURDAY THE GFS/ECMWF HAVE COME INTO A LITTLE BETTER
AGREEMENT THAN PREVIOUS RUNS. SUNDAY WILL START OUT COLD WITH LOWS
FALLING INTO THE MID 20S...BUT TEMPS WILL MODERATE A BIT DURING THE
AFTERNOON WITH HIGHS IN THE MID 50S. THE SURFACE HIGH WILL SHIFT
FURTHER EAST AND THE FLOW WILL BECOME MORE EASTERLY ON MONDAY. TEMPS
WILL MODERATE A BIT BY MONDAY AS H850/H925 TEMPS WARM A BIT WITH
HIGHS IN THE MID TO UPPER 50S. MOISTURE WILL BE ON THE INCREASE BY
TUESDAY AND THIS MAY ALLOW SOME SHOWERS TO DEVELOP INTO WEDNESDAY. A
MORE ACTIVE PATTER LOOKS LIKE IT WILL DEVELOP AS WE GET INTO THE
MID/LATE PART OF NEXT WEEK.
STUCK PRETTY CLOSE TO GUIDANCE TEMPS THROUGH THE PERIOD...BUT DID DO
THE USUAL CUTS TO GUIDANCE LOWS IN THE AREAS THAT GENERALLY COOL
BELOW GUIDANCE UNDER STRONG RADIATIONAL COOLING. ALSO CUT BELOW
GUIDANCE HIGHS ON SATURDAY AS H925/H850 TEMPS COMBINED WITH COLD AIR
ADVECTION SHOULD KEEPS HIGHS IN THE LOW 50S. STUCK WITH OR CLOSE TO
GUIDANCE POPS/TEMPS BEYOND SATURDAY./15/
&&
.AVIATION...
MIX OF IFR AND MVFR CONDITIONS CONTINUE THIS MORNING AT
TAF SITES ACROSS THE AREA...BUT WILL IMPROVE FROM WEST TO EAST AS
SKIES CLEAR DURING THE AFTERNOON. OTHER THAN AT KGTR...WINTRY
PRECIPITATION HAS JUST ABOUT COME TO AN END AT SITES...WITH PATCHES
OF LIGHT RAIN FALLING ELSEWHERE AS AN STRONG UPPER TROUGH SWINGS
ACROSS THE REGION. LOOK FOR ANY PATCHY PRECIPITATION TO COME TO AN
END BY 18Z. NORTHWEST WINDS WILL AGAIN BE BREEZY BUT WILL DIMINISH
DURING THE LATE AFTERNOON AND OVERNIGHT. THERE IS A LOW END RISK FOR
SOME RESTRICTED VISIBILITIES LATE TONIGHT AS TEMPERATURES COOL AND
GROUND FOG DEVELOPS. IF THIS OCCURS...TEMPERATURES WILL BE WELL BELOW
FREEZING AND FREEZING FOG IS POSSIBLE. AT THIS TIME...THIS IS A LOW
PROBABILITY EVENT AND WILL NOT MENTION IN OFFICIAL TAFS. WITH THAT
SAID...A HEAVY FROST IS EXPECTED ACROSS THE ENTIRE AREA. /19/ &&
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 40 25 52 27 / 0 0 0 0
MERIDIAN 40 25 53 24 / 8 0 0 0
VICKSBURG 42 22 52 24 / 0 0 0 0
HATTIESBURG 45 26 53 28 / 0 0 0 0
NATCHEZ 43 24 52 28 / 0 0 0 0
GREENVILLE 39 24 48 26 / 5 0 0 0
GREENWOOD 39 23 51 24 / 11 0 0 0
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$