FXUS61 KALY 271120
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
620 AM EST FRI NOV 27 2009

.SYNOPSIS...
A COMPLEX STORM SYSTEM WILL IMPACT THE NORTHEAST TODAY 
INTO SATURDAY WITH UNSETTLED WEATHER INCLUDING RAIN...AND SOME 
SNOW...ESPECIALLY ACROSS THE HIGHER ELEVATIONS...AND STRONG GUSTY 
WINDS. THE STORM WILL MOVE INTO THE CANADIAN MARITIMES SATURDAY INTO 
SUNDAY...WITH HIGH PRESSURE BUILDING IN FROM THE SOUTHEAST WITH 
DIMINISHING WINDS AND TRANQUIL WEATHER. 

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
FOR TODAY...STRONG CYCLOGENESIS CONTINUES AS THE COASTAL LOW MOVES 
FROM JUST 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 
THIS MRNG THE LOW IS EXPECTED TO BE BTWN 991 AND 993 HPA WITH THE 
NAM NOW FARTHEST W AND ECMWF FARTHEST NE. BEST FRONTOGENESIS H10-H7 
LOOKS TO OCCUR THIS MORNING ACROSS CENTRAL NEW ENGLAND AND THEN 
QUICKLY LIFTS INTO MAINE THIS AFTERNOON. H8-H7 DEFORMATION AXIS 
PIVOTS THROUGH EASTERN MOHAWK AND HUDSON VALLEYS SOUTHEAST INTO 
LITCHFIELD HILLS EARLY THIS AFTERNOON WITH THIS AFTERNOON BEING THE 
MOST FAVORABLE PERIOD FOR HEAVIER QPF. HAVE ACCUMULATING SNOW IN THE 
GRIDS MAINLY AT ELEVATIONS ABOVE 2000 FEET AS FREEZING LEVEL WILL BE 
LOWERING BUT NOT UNTIL LATE IN THE DAY AND TEMPS BELOW 2000 FEET 
WILL REMAIN MARGINAL FOR SNOW ACCUMULATION DURING THE DAY. THE 
HIGHEST ACCUMULATIONS TODAY LOOK TO BE ACROSS THE HIGHER TERRAIN IN 
HAMILTON COUNTY WHERE 1 TO 2 INCHES OF SNOW ACCUMULATION EXPECTED. 
THE REMAINDER OF FA WILL HAVE MAINLY RAIN AS H850-700 PARTIAL 
THICKNESSES ARE BELOW 1540 METERS DURING THE DAY...BUT THE 1000-850 
VALUES ARE STILL ABOVE 1310 METERS THROUGH AT LEAST 18Z. TEMPS WILL 
MAINLY HOVER IN THE UPPER 30S TO LOWER 40S TODAY. THE MAIN CONCERN 
LATER TODAY WILL BE THE STRENGTHENING PRESSURE GRADIENT WHICH WILL 
RESULT IN WINDS INCREASING TO 15 TO 25 MPH WITH GUSTS OVER 35 MPH 
BEFORE DAYS END ESPECIALLY ACROSS THE EASTERN CATSKILLS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
FOR TONIGHT...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 970 AND 980 HPA SOMEWHERE BTWN DOWNEAST MAINE AND
NORTHEAST PORTIONS OF THE CANADIAN MARITIMES...BUT BY THIS TIME
THE QPF ACRS FA IS DECREASING RAPIDLY WITH QPF AMOUNTS GENERALLY A
TENTH TO A QUARTER OF AN INCH. THUS ACCUMULATING SNOWS APPEAR TO
BE LIMITED TO GENERALLY 1 TO 3 INCHES MAINLY ACROSS THE NORTHERN
MOUNTAINS. THE ONE CERTAINTY FOR FRIDAY NIGHT IS THAT CONDITIONS
WILL BECOME VERY WINDY ACROSS FA AND PRESSURE GRADIENT APPEARS TO
TIGHTEN EVEN FURTHER WITH SUBSEQUENT MODEL RUNS. ISALLOBARIC
COUPLET CONTINUES TO BE IMPRESSIVE WITH +6 TO -8 ON NAM AND +4 TO
-13 ON GFS AT 12Z SATURDAY. IN ADDITION 0-30 MB AGL WINDS CONTINUE
TO STRENGTHEN WITH NAM NOW INDICATING FLAGS ABOVE 50 KTS ACRS MUCH
OF THE EASTERN CATSKILLS AS WELL AS PORTIONS OF THE SOUTHERN
ADIRONDACKS...BERKSHIRES AND SOUTHERN GREEN MOUNTAINS BETWEEN 06Z
AND 18Z SAT. IT LOOKS AS THOUGH THESE AREAS WILL SEE GUSTS OVER
58 MPH AND HAVE ISSUED A HIGH WIND WARNING FROM 6 PM THIS EVENING
UNTIL 6 PM SATURDAY FOR THESE AREAS. ELSEWHERE MOST AREAS LOOK TO
HAVE GUSTS OVER 40 KNOTS...SO HAVE ISSUED A WIND ADVISORY FOR THE 
REMAINING ZONES FOR THE SAME TIME PERIOD. ALSO CONCERNED ABOUT 
CHANNELED FLOW IN E-W ORIENTED VALLEYS SUCH AS THE MOHAWK AND 
CATSKILL CREEK DRAINAGE...BUT HAVE NOT INCLUDED THESE AREAS IN THE 
WARNING AT THIS TIME...BUT THEY WILL NEED TO BE MONITORED CLOSELY.

ON SATURDAY...THE LOW BECOMES VERTICALLY STACKED AND OCCLUDED
OVER NORTHERN PORTIONS OF THE CANADIAN MARITIMES WITH STRONG
PRESSURE GRADIENT STILL IN PLACE ACROSS MUCH OF FA UNTIL LATE IN
THE DAY WHEN IT STARTS TO SLACKEN. HIGHER MIXING HEIGHTS OVER 3
KFT IN SOME AREAS EXIST SATURDAY MORNING THAN TONIGHT WHICH WILL
GIVE WINDS AN EVEN BETTER CHANCE TO MIX DOWN. 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 LOWER 30S.

SUNDAY...LOOKS DRY AS HIGH PRESSURE BUILDS INTO FA WITH HIGHS IN
THE UPPER 30S TO AROUND 50 AND MUCH LESS WIND. CLOUDS WILL
INCREASE AGAIN ESPECIALLY DURING THE AFTERNOON AHEAD OF THE NEXT
SHORT WAVE.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
TRENDS IN THE GLOBAL MODELS AND FORECASTER DISCUSSIONS CONTINUE TO 
FAVOR A FRONTAL PASSAGE ON MONDAY.  HOWEVER...QUESTIONS REMAIN JUST 
HOW EXTENSIVE THE PRECIP SHIELD WILL BE AND DID NOT WANT TO GO 
LIKELY POPS AT THIS TIME.  IN ADDITION...THERE ARE TRENDS POINTING 
TOWARD MORE ANAFRONT CHARACTERISTICS AS MAIN UPPER JET REMAINS 
BEHIND THE SURFACE FRONTAL ZONE.  EITHER WAY...BAROCLINICITY 
INCREASES SUNDAY NIGHT INTO MONDAY FROM THE TENNESSEE AND OHIO 
VALLEY INTO NEW ENGLAND.  THERMAL PROFILES REMAIN A CHALLENGE AS 
THIS ROUND OF THE MODEL SUITES SUGGEST MAINLY SNOW FOR THE DACKS 
WITH A RAIN/SNOW LINE ACROSS THE MOHAWK RIVER AND CAPITAL REGION 
WITH MAINLY RAIN SOUTH AND EAST OF CAPITAL REGION.  A FEW INCHES OF 
SNOW ARE POSSIBLE BUT WILL AWAIT CONTINUED TRENDS BEFORE 
HIGHLIGHTING THIS POTENTIAL INTO THE HWO THIS MORNING.

IN THE WAKE OF THE FRONTAL PASSAGE...COLD ADVECTION COMMENCES WITH 
AVERAGE 850MB TEMPS DROPPING TOWARD -10C.  THIS WILL BE SURE TO 
ACTIVATE LAKE ONTARIO FOR ADDITIONAL LAKE EFFECT SNOW FOR PORTIONS 
OF THE DACKS AND MOHAWK VALLEY.  GLOBAL MODELS DIVERGE FROM HERE AS 
ECMWF SHORT WAVE ENERGY EITHER DIGS A BIT AND MOVES ACROSS THE 
REGION OR THE GFS IDEA OF A FLATTER WAVE.  IT SEEMS...WHATEVER MOVES 
THROUGH THE FLOW...THIS LEADS INTO A PERIOD OF WARM ADVECTION FOR 
THE MID WEEK PERIOD WITH THE CHANCE FOR A LITTLE OVERRUNNING 
EVENT.   

THEN CUT OFF 4-CORNERS CONUS LOW EJECTS INTO TEXAS AND GULF OF 
MEXICO LATER IN THE WEEK.  AS ONE WOULD EXPECTED...A VARIETY OF 
SOLUTIONS AND WE WILL ONLY PLACE SLIGHT CHANCE POPS AT THIS TIME. 

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
IFR CONDITIONS PREVAIL THIS MORNING...ESPECIALLY WITH RESPECT TO 
RADIATIONAL FOG WHICH HAS RESULTED IN 1/4SM VIS WHICH WILL CONTINUE 
FOR THE NEXT COUPLE OF HOURS.  AS SEEN ON THE RADAR 
MOSAIC...REFLECTIVITIES COVERAGE REMAINS OVER CENTRAL NY AND 
ADDITIONAL SHOWER ACTIVITY COMING NORTHWARD INTO ADJACENT WESTERN  
NEW ENGLAND.  AS THIS STORM CONTINUES TO INTENSIFY OFF THE MID 
ATLANTIC COAST...PRECIPITATION WILL INCREASE IN COVERAGE THROUGH 
THIS FRIDAY MORNING KEEPING MVFR/IFR CONDITIONS WHICH SHOULD BE 
MAINLY FROM CIGS.  

WINDS WILL BECOME MORE PROBLEMATIC LATE TODAY INTO TONIGHT WITH AN 
INCREASED WEST-NORTHWEST WIND FLOW.  WILL CONTINUE WITH LLWS TONIGHT 
WITH SFC WIND GUSTS BETWEEN 25-35 KTS TO START.
 
OUTLOOK... 
SAT-SAT NGT...MVFR/IFR...-SHRA CHG TO -SHSNRA. LLWS. WINDY. 
SUN...VFR. NO SIG WX.
SUN NT-MON...MVFR/IFR. -RA/-SN.
TUE...VFR/MVFR.  CHC -SHRA/-SHSN.

&&

.HYDROLOGY...
WIDESPREAD PRECIPITATION EXPECTED FROM TODAY THROUGH SATURDAY...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 FROM
JUST BELOW A HALF INCH TO JUST OVER AN INCH 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 OF AROUND 1 TO 2 FEET WILL OCCUR ON RIVERS BUT
THEY SHOULD REMAIN WELL 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...WIND ADVISORY FROM 6 PM THIS EVENING TO 6 PM EST SATURDAY FOR 
     CTZ001-013.
NY...HIGH WIND WARNING FROM 6 PM THIS EVENING TO 6 PM EST SATURDAY 
     FOR NYZ033-042-047-051-058-063-082.
     WIND ADVISORY FROM 6 PM THIS EVENING TO 6 PM EST SATURDAY FOR 
     NYZ032-038>041-043-048>050-052>054-059>061-064>066-083-
     084.
MA...HIGH WIND WARNING FROM 6 PM THIS EVENING TO 6 PM EST SATURDAY 
     FOR MAZ001-025.
VT...HIGH WIND WARNING FROM 6 PM THIS EVENING TO 6 PM EST SATURDAY 
     FOR VTZ013-014.
     WIND ADVISORY FROM 6 PM THIS EVENING TO 6 PM EST SATURDAY FOR 
     VTZ015.

&&

$$
SYNOPSIS...11
NEAR TERM...11
SHORT TERM...11
LONG TERM...BGM
AVIATION...BGM
HYDROLOGY...11

WWW.WEATHER.GOV/ALBANY