FXUS61 KALY 261129
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
630 AM EST THU NOV 26 2009
.SYNOPSIS...
A WEAK AREA OF HIGH PRESSURE WILL BE OVER OUR REGION TODAY
WITH RELATIVELY MILD...CLOUDY...AND DRY CONDITIONS. A COMPLEX STORM
SYSTEM WILL IMPACT THE NORTHEAST TONIGHT INTO SATURDAY WITH
UNSETTLED WEATHER INCLUDING RAIN...AND SNOW...ESPECIALLY ACROSS THE
HIGHER ELEVATIONS...AND BLUSTERY WINDS.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY THIS MORNING STRATUS COVERED MUCH OF THE FA WITH AREAS OF
FOG AND AS A RESULT TEMPS HAVE REMAINED VIRTUALLY STEADY FOR THE
LAST SEVERAL HOURS AND WILL DO SO THROUGH MID MORNING WITH FOG IN
SOME AREAS UP UNTIL 14Z OR 15Z. TODAY LOOKS TO BE THE TRANSITION
DAY FROM OUR RELATIVELY QUIET WEATHER PATTERN TO A MUCH MORE
ACTIVE PATTERN. WHILE IT LOOKS TO BE RELATIVELY MILD TODAY DO...NOT
SEE MUCH SUN AS LOW LEVEL MOISTURE REMAINS TRAPPED BENEATH A
STRENGTHENING INVERSION AND MODEL SOUNDINGS AND RH PROFILES ARE
MOIST FOR MUCH OF THE DAY. THUS AT BEST ONLY EXPECT A FEW BREAKS
OF SUN AND TEMPS WILL ONLY RISE AROUND 5 DEGREES FROM MORNING LOWS
IN MOST AREAS. HAVE FORECAST HIGHS CLOSER TO MET TEMPS THAN MAV
TEMPS WITH MOST AREAS REACHING THE UPPER 40S TO LOWER 50S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
FOR TONIGHT...THE MODEL AND ENSEMBLE GUIDANCE CONTINUES TO HAVE
DISCREPANCIES ON THE HANDLING OF THE COASTAL LOW AS WELL AS THE
GREAT LAKES LOW AND ASSOCIATED CLOSED/CUTOFF UPPER LOW. AGREE WITH
THE PMDHMD THAT THE GEM GLOBAL AND ECMWF HAVE THE BEST HANDLE ON
THE COASTAL SYSTEM THROUGH FRIDAY NIGHT. INITIALLY THE PARTIAL
THICKNESS VALUES AND H8 TEMPS ARE WARM ENOUGH TO SUPPORT ALL RAIN
WITH ONSET OF PCPN THIS EVENING...BUT LATER TONIGHT AS H8 0C
ISOTHERM MOVES INTO WESTERN ADIRONDACKS AND WESTERN PORTIONS OF
EASTERN CATSKILLS EXPECT THAT A CHANGEOVER TO SNOW WILL START TO
OCCUR. EXPECT LOWS TO BE IN THE MID 30S TO LOWER 40S.
FOR FRIDAY...STRONG CYCLOGENESIS CONTINUES FROM EAST OF CAPE COD
INTO THE GULF OF MAINE...BUT THE EXACT POSITION OF THE SYSTEM WILL
BE CRITICAL IN TERMS OF QPF...PCPN TYPE AND TEMPS AND THAT IS THE
DIFFICULT PART OF THE FORECAST AS AT 12Z FRI THE LOW IS EXPECTED
TO BE BTWN 990N AND 996 HPA WITH THE GFS FARTHEST W AND ECMWF
FARTHEST NE. MEANWHILE THE THE PLACEMENT OF THE H500 CLOSED
CIRCULATION IS CRITICAL FOR WHERE SNOW LEVELS FALL DURING THE DAY
WITH THE GFS FARTHEST SOUTH AND EAST IN THE EASTERN GREAT LAKES
NEAR THE WEST END OF LAKE ONTARIO WITH THE OTHER MODELS FARTHER
NORTH AND WEST. PROVIDED THAT THE MODELS WHICH HAVE THE CLOSED LOW
FARTHER NORTH AND WEST ARE CORRECT THEN THE H8-H7 DEFORMATION AXIS
SHOULD PIVOT ACROSS THE WESTERN ADIRONDACKS AND EASTERN CATSKILLS
FRIDAY AFTERNOON WHICH WOULD BE THE MOST FAVORABLE PERIOD FOR
HEAVIER QPF. HAVE ACCUMULATING SNOW IN THE GRIDS MAINLY AT
ELEVATIONS ABOVE 1500 FEET AS FREEZING LEVEL WILL BE LOWERING
DURING THE DAY ON FRIDAY. THE HIGHEST ACCUMULATIONS LOOK TO BE IN
THE WESTERN ADIRONDACKS WITH 2 TO 4 INCHES AND 1 TO 3 INCHES
ACROSS THE HIGHER TERRAIN OF THE EASTERN CATSKILLS WITH UP TO AN
INCH ACROSS THE HIGHEST TERRAIN OF THE SOUTHERN GREEN MOUNTAINS
AND BERKSHIRES. THE REMAINDER OF FA WILL HAVE RAIN OR A MIXTURE OF
RAIN AND SNOW WITH LITTLE IF ANY ACCUMULATION AS TEMPS HOVER IN
THE UPPER 30S TO LOWER 40S.
FOR FRIDAY NIGHT THE FREEZING LEVEL CONTINUES TO LOWER AND MOST IF
NOT ALL OF THE FA WILL SEE A CHANGEOVER TO SNOW AS LOW DEEPENS TO
BETWEEN 974 AND 979 HPA SOMEWHERE BTWN DOWNEAST MAINE AND NORTHEAST
PORTIONS OF THE CANADIAN MARITIMES...BUT BY THIS TIME THERE IS EVEN
MORE UNCERTAINTY IN THE AMOUNT OF QPF THAT WILL REMAIN AND THE EXACT
TRACK OF THE SYSTEM. THE ECMWF HAS LESS THAN A QUARTER OF AN INCH OF
QPF ACROSS FA BTWN 00Z AND 12Z SAT WHILE THE GFS STILL HAS UP A
QUARTER TO A HALF INCH ACROSS THE WESTERN ADIRONDACKS...SOUTHERN
VERMONT AND THE NORTHERN BERKS. WHILE STILL SIDING WITH THE ECMWF
WILL INCLUDE THE POSSIBILITY OF HIGHER AMOUNTS IN HWO AND HAVE
SEPARATED OUT WESTERN ADIRONDACKS FROM THE OTHER MOUNTAIN ZONES AS
WESTERN ADIRONDACKS MAY NEED A LATER ISSUANCE OF A WINTER STORM
WATCH...WINTER STORM WARNING AND OR WINTER WEATHER ADVISORY...BUT
JUST TOO MUCH UNCERTAINTY AT THIS TIME. OTHER MOUNTAIN ZONES
INCLUDING EASTERN CATSKILLS...SOUTHERN GREEN MOUNTAINS AND
BERKSHIRES DO NOT SEEM TO HAVE ENOUGH QPF AS SNOW...ALTHOUGH A
WINTER WEATHER ADVISORY MAY BE NEEDED IN THESE AREAS. DO TO THE
UNCERTAINTY IN TRACK AND QPF DID NOT ISSUE ANY HEADLINES AT THIS
TIME.
THE ONE CERTAINTY FOR FRIDAY NIGHT IS THAT CONDITIONS WILL BECOME
VERY WINDY ACROSS FA AND ECMWF POSITION OF SURFACE LOW IS IN LINE
WITH COMPOSITE SURFACE ANALYSIS OF CURRENT CSTAR COOL SEASON HIGH
WIND STUDY. ISALLOBARIC COUPLET ALSO IMPRESSIVE AS +4 TO -10
TRANSITIONS TO +7 TO -11. IN ADDITION 0-30 MB AGL WINDS HAVE FLAGS
ABOVE 50 KTS ACRS PARTS OF THE EASTERN CATSKILLS AT 06Z SAT AND
ACROSS THE EASTERN CATSKILLS AND SOUTHERN VERMONT AT 12Z SAT. IT
LOOKS AS THOUGH MUCH OF HIGHER TERRAIN WILL SEE GUSTS OVER 45 MPH
AS WELL AS CHANNELED FLOW IN E-W ORIENTED VALLEYS SUCH AS THE
MOHAWK. HAVE THUS CONTINUED TO INCLUDE IN HWO AS TOO EARLY FOR
HEADLINE BEING FRIDAY NIGHT INTO SATURDAY MORNING. A WIND ADVISORY
OR HIGH WIND WARNING MAY BE NEEDED WHICH MAY BE PRECEDED BY A
HIGH WIND WATCH.
ON SATURDAY...THE LOW BECOMES VERTICALLY STACKED AND OCCLUDED OVER
NORTHERN PORTIONS OF THE CANADIAN MARITIMES. ANY LINGERING PCPN
WILL BE TAPERING OFF BY AFTERNOON. LOW LEVEL WIND FIELDS WILL
STILL BE STRONG ESPECIALLY DURING THE MORNING...BUT EXPECT SOME
SUBSIDENCE/DOWN SLOPING DURING THE AFTERNOON. ANY UPSLOPE SNOW
LOOKS TO BE CONFINED TO THE NORTHERN PORTIONS OF THE SOUTHERN
ADIRONDACKS AND THE SOUTHERN GREEN MOUNTAINS. HIGHS WILL BE
IN THE MID 30S TO MID 40S.
ON SATURDAY NIGHT...ANY LINGERING SNOW SHOWERS EXPECTED TO BE
CONFINED TO THE NORTHERN HALF OF THE FA WITH THE SNOW ENDING LAST
ACROSS THE WESTERN ADIRONDACKS WHERE A LITTLE LAKE ENHANCEMENT IS
POSSIBLE. FOR NOW WILL JUST GO WITH CHANCE POPS. LOWS SATURDAY
NIGHT EXPECTED TO BE IN THE MID 20S TO AROUND 30.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
A TRANQUIL END TO THE HOLIDAY WEEKEND AS GLOBAL MODELS ALL POINT
TOWARD A NARROW WEDGE OF HIGH PRESSURE TO QUICKLY MOVE ACROSS THE
SOUTHEAST CONUS AND ITS ASSOCIATED NORTHERN EXTENT THROUGH THE
REGION. UPSTREAM...PIECE OF THE POTENT PACIFIC BREAKS OFF WITH
NORTHERN STREAM TRANSVERSING THE NORTHERN TIER OF THE COUNTRY. WITH
THE AFOREMENTIONED HIGH PRESSURE OFF THE SOUTHEAST CONUS...RETURN
FLOW WILL ALLOW GULF OF MEXICO MOISTURE TO ADVANCE NORTHEAST IN
ADVANCE OF THIS NEXT SYSTEM. CLOUDS WILL QUICKLY INCREASE SUNDAY
NIGHT WITH LIGHT PRECIP EXPECTED TO DEVELOP OVERNIGHT INTO MONDAY.
THERMAL PROFILES POINT TO RAIN/SNOW MIX CHANGING TO PRIMARILY RAIN
MONDAY MORNING WITH WARM ADVECTION REGIME. HOWEVER...THIS WILL
LIKELY BE SHORT LIVED AS GUIDANCE REVEALS A RAPID INCREASE IN THE
BAROCLINICITY ON MONDAY WITH POTENTIAL FOR SURFACE WAVE DEVELOPMENT
OVER THE OHIO RIVER VALLEY. THIS USUALLY RESULTS IN THE COLD AIR TO
QUICKLY UNDERCUT THE WARMER AIR AND A TRANSITION BACK TO A RAIN/SNOW
MIX EXPECTED LATE MONDAY INTO MONDAY NIGHT. THERE WILL BE A WINDOW
OF OPPORTUNITY FOR MOST OF THE REGION WITH AN ACCUMULATING SNOWFALL
EVENT...ESPECIALLY IF BANDED PRECIP IS POST-FRONTAL AS SUGGESTED BY
THE ECMWF /TOO EARLY TO GET SPECIFIC/ LATE MONDAY INTO MONDAY NIGHT.
THIS SYSTEM QUICKLY DEPARTS TUESDAY...IN ITS WAKE...MUCH COLDER AIR
MASS WHICH WILL BE MIGRATING OVER THE WARM WATERS OF THE GREAT
LAKES. THIS WILL LIKELY BRING ABOUT LAKE EFFECT SNOW FOR PORTIONS
OF THE DACKS. IN ADDITION...WITH COLD CYCLONIC FLOW...INSTABILITY
SHOWERS WHICH WILL LIKELY BE MORE CONCENTRATED OVER THE TERRAIN WITH
UPSLOPE CONDITIONS. BY MID NEXT WEEK...ANOTHER SURFACE RIDGE OF
HIGH PRESSURE AND WARMING THERMAL PROFILES FOR TRANQUIL CONDITIONS.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
...IFR CONDITIONS TO PREVAIL THE NEXT SEVERAL HOURS FOR ALL TAF
SITES...
A VARIETY OF AVIATION ISSUES THIS MORNING WITH COMPLEX SKY/STRATUS
DECK AND FOG FORMATION DUE TO HIGH LOW LEVEL MOISTURE CONTENT. THE
FOG SHOULD LIFT INTO A STRATUS DECK LATER THIS MORNING FOR ALL TAFS
LOCATIONS IN THE HUDSON RIVER VALLEY AS HEATING COMMENCES.
THROUGHOUT THE DAY...WE WILL WATCH COASTAL STORM OFF THE SOUTHEAST
COAST BEGIN TO TRACK NORTHEAST. THE REGION WILL BEGIN TO FEEL ITS
IMPACTS LATE TODAY INTO TONIGHT.
HEADING INTO TONIGHT...COMPLEX STORM EVOLVES WHICH WILL BECOME AN
INCREASED AVIATION CONCERN WITH A COMBINATION OF PRECIP/CIGS-VIS.
OUTLOOK...
FRI...MVFR/IFR...-SHRA. CHC LLWS. BECMG WINDY.
FRI NGT-SAT NGT...MVFR/IFR...-SHRA CHG TO -SHSNRA. POSS LLWS. WINDY.
SUN...VFR. NO SIG WX.
MON...MVFR/IFR. -RA/-SN.
&&
.HYDROLOGY...
THE NEXT CHANCE OF WIDESPREAD PRECIPITATION WILL BE FROM LATER
TONIGHT INTO THE FIRST HALF OF THE WEEKEND...AS A STRONG STORM
IS EXPECTED TO IMPACT THE REGION. THERE IS STILL A HIGH AMOUNT OF
UNCERTAINTY WITH REGARDS TO THE EVOLUTION OF THE STORM AND
ASSOCIATED QPF. QPF AMOUNTS LOOK TO BE SOMEWHERE IN THE HALF INCH
TO 1.35 INCH RANGE AND FOR NOW HAVE HIGHEST AMOUNTS ACROSS
NORTHERN PORTION OF HSA. DEPENDING ON HOW THE STORM EVOLVES...SOME
OF THE PRECIP MAY FALL AS SNOW AS WELL...ESPECIALLY ACROSS THE
HIGHER ELEVATIONS. AT THIS TIME IT APPEARS SOME RISES WILL OCCUR
ON RIVERS BUT SHOULD REMAIN WITHIN THEIR BANKS. THE PRECIPITATION
WILL START TO TAPER OFF BY SATURDAY AFTERNOON AS THE STORM PULLS
AWAY INTO THE CANADIAN MARITIMES. WEAK HIGH PRESSURE IS EXPECTED
TO RESULT IN DRY CONDITIONS ON SUNDAY.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING
OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE
VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON
OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...11
NEAR TERM...11
SHORT TERM...11
LONG TERM...BGM
AVIATION...BGM
HYDROLOGY...11
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