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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KALY 092349
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
649 PM EST TUE FEB 9 2010

.SYNOPSIS...
HIGH PRESSURE WILL SLIDE EAST ACROSS THE REGION DURING THE EVENING
AND OFF THE NEW ENGLAND COAST OVERNIGHT. LOW PRESSURE WILL DEVELOP
ALONG THE MID ATLANTIC COAST LATE TONIGHT...AND MOVE NORTHEAST
PASSING SOUTH OF LONG ISLAND BY LATE WEDNESDAY. THIS WILL BRING SNOW
TO MUCH OF THE REGION ON WEDNESDAY...WITH THE BEST CHANCE FOR HEAVY
SNOWFALL OCCURRING SOUTH AND EAST OF ALBANY.

&&

.NEAR TERM /TONIGHT/...
AS OF 330 PM...THE HIGH CLOUDS FROM THE DEVELOPING UPSTREAM STORM
WERE OVERSPREADING THE REGION. H20 WATER LOOP INDICATES THE UPPER
AIR STORM NOW CROSSING OVER SAINT LOUIS...TRACKING MORE EAST ALONG
THE I-70 CORRIDOR. THIS SHOULD BE THE PATH OF THE UPPER AIR
LOW...STRAIGHT TO OFF THE DELMARVA PENINSULA BY LATE WEDNESDAY. THE
"OLD" SURFACE LOW ASSOCIATED WITH THE UPPER AIR LOW LOCATED OVER THE
OHIO VALLEY...WILL RAPIDLY GIVE ENERGY TO A MUCH STRONG SURFACE
STORM OFF THE CAROLINAS TONIGHT...WHICH WILL THEN TURN NORTHEAST AND
TRACK SOMEWHERE SOUTH OF LONG ISLAND...PROBABLY SOUTH AND EAST OF
THE ALBANY "BENCHMARK" (JUST OFF EASTERN LONG ISLAND).

UPGRADED THE WINTER STORM WATCH TO A WINTER STORM WARNING FOR THE
SOUTHERN COUNTIES /ULSTER...DUTCHESS...AND LITCHFIELD/...AND HAVE
ALSO INCLUDED GREENE...COLUMBIA...AND BERKSHIRE IN THE WARNING AS
WELL...WITH A GENERAL 6-12 INCHES OF SNOW EXPECTED...WITH UP TO 16
INCHES IN THE LITCHFIELD HILLS.

IN ADDITION...HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE
GREATER CAPITAL REGION...SOUTHERN VERMONT...AND THE MOHAWK AND
SCHOHARIE VALLEYS FOR A GENERAL 3-6 INCH SNOWFALL /WITH LOCALLY UP
TO 8 INCHES/.

THE SNOW SHOULD BEGIN JUST PRIOR TO DAYBREAK WEDNESDAY...AND
CONTINUE THROUGH MUCH OF THE DAY.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
BOTH DETERMINISTIC MODELS AND ENSEMBLE GUIDANCE HAVE NOW TRENDED THE
STORM SLIGHTLY FURTHER BACK TO THE NORTH WITH MORE QPF. THE OUTLIER
IS THE EUROPEAN WHICH WHILE ALSO TRENDING THE SURFACE LOW FURTHER
NORTH...HAS THE LOWEST QPF GIVING ALBANY ONLY AROUND 0.15 INCHES
LIQUID EQUIVALENT. HOWEVER...THE WRF GIVES ALBANY NEARLY FIVE TIMES
THAT AMOUNT!

OUR FORECAST GOES IN BETWEEN MORE IN LINE WITH THE 12Z GFS WATER
EQUIVALENT WHICH GIVES ALBANY AROUND A QUARTER OF INCH.
OBVIOUSLY...THIS IS A MODERATE CONFIDENCE FORECAST AT BEST.

IT APPEARS TO US THE BEST FRONTOGENESIS AND MOISTURE CONVERGENCE
WILL REMAIN JUST SOUTH OF ALBANY BUT SLOPING TOWARD THE CAPITAL
DISTRICT. THERE IS A LARGE AREA OF H850 CIRCULATION WITH AN EASTERLY
FLOW WHICH WARRANTS SNOW TO FALL NOT ONLY IN ALBANY...BUT WELL NORTH
OF TOWN. OUR THINKING THOUGH IS THAT THE HEAVIEST SNOW BANDS SHOULD
BE REMAIN JUST SOUTH AND EAST OF ALBANY. HOWEVER...WITH LOWER THAN
"IDEAL" CONFIDENCE THERE IS STILL OPPORTUNITY FOR THE MAX QPF TO
MOVE SOUTH OR NORTH.

SNOW RATIOS WILL START OFF CLOSER TO 10:1 (MAYBE EVEN A LITTLE LOWER
SOUTH) BUT AS THE STRONG DYNAMICS (ASSOCIATED WITH THE UPPER AIR
LOW) MOVE TO OUR SOUTH...THE SNOW RATIO WILL LIKELY INCREASE TO
ABOUT 15:1 BY THE END OF THE STORM. MODEL SOUNDINGS INDICATE ALL
SNOW FOR OUR ENTIRE AREA...BUT THE SNOW GROWTH REGION WILL NOT
INITIALLY BE OPTIMAL BUT WILL BECOME THAT IN TIME.

IF THE SURFACE AND H800/H700 CLOSED LOW PORTION OF THE STORM WERE TO
MOVE EVEN LITTLE FURTHER NORTH...ALBANY AND EVEN
PLACES NORTH COULD BE IN FOR A SIGNIFICANT SNOWFALL.

STAY TUNED.

THE STORM WILL BE WELL EAST OF CAPE BY WEDNESDAY NIGHT AND THE SNOW
WILL BE WINDING DOWN. A TRAILING LINE OF CONVERGENCE (POSSIBLY
DRIVEN IN PART BY MOHAWK HUDSON CONVERGENCE) WILL LIKELY LINGER SNOW
A LITTLE LONGER IN THE CAPITAL DISTRICT AND MOHAWK VALLEY FOR AWHILE
WEDNESDAY EVENING.

THEN...AS THE STORM CONTINUE TO BOMB OFF THE CANADIAN MARITIMES...IT
WILL SPIN AND GO NOWHERE MIGHT FAST...THANKS TO A CONTINUED
PERSISTENTLY GREENLAND RIDGE (KNOWN AS THE GREENLAND BLOCK AND ONE
OF THE KEY PLAYERS FOR A NEGATIVE NORTH ATLANTIC OSCILLATION
REGIME). THIS WILL TRANSLATE TO A PRETTY GOOD PRESSURE GRADIENT
BETWEEN THIS NEARLY STATIONARY LOW WELL TO THE NORTHEAST AND HIGH
PRESSURE TO THE SOUTHWEST. EXPECT A RETURN TO PARTIAL SUNSHINE AND
BLUSTERY CONDITIONS THURSDAY AND FRIDAY. THE NORTHWEST FLOW WILL
PRODUCE SOME LAKE ENHANCED MOISTURE OFF ONTARIO AND REAP SCATTERED
SNOW SHOWERS IN THE USUAL UPSLOPE AREAS (CATSKILLS/MOHAWK
VALLEY/DACKS AND GREENS). THESE SNOW SHOWERS WILL LIKELY NOT AMOUNT
TO A WHOLE LOT...EXCEPT POSSIBLY ACROSS THE HIGHEST SOUTHERN GREENS
AND DACKS.

TEMPERATURES LOOKS TO BE SEASONABLE AS THE AIR MASS OVER IS MODIFIED
ARCTIC AIR. HIGH TEMPERATURES WILL TOP IN 20S TO AROUND 30 (HUDSON
VALLEY) AND LOWS IN THE TEENS (SOME SINGLE NUMBERS NORTH). GENERALLY
WENT WITH A MET/MAV BLEND EXCEPT A LITTLE COLDER THAN ALL MODEL
GUIDANCE SOUTH ON WEDNESDAY DUE TO FALLING SNOW ANTICIPATED TO COOL
THE COLUMN.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
MOS GUIDANCE IS MODEL OF CHOICE FOR TEMPERATURES...SO HAVE POPPED
ALL PARAMETERS WITH IT.  WE START OUT WITH A PERSISTENT BROAD
NORTHWESTERLY FLOW BEHIND RETROGRADING LOW PRESSURE OVER
NEWFOUNDLAND.  WE HAVE THUSLY INCLUDED SLGT CHC -SHSN...MAINLY FOR
NORTH AND WEST OF THE CAPITAL REGION THROUGH THE WEEKEND.  FLURRIES
WILL PROBABLY BE ALL THERE IS.  ACCORDING TO THE GFS...LOW PRESSURE
FORMING OFF THE COLORADO/NORTHERN ROCKIES IS EXPECTED TO TRACK EAST
ACROSS THE OHIO VALLEY AND MID-ATLANTIC REGION SUNDAY THROUGH
MONDAY...THEN TAKE A TURN NORTHEAST ALONG THE NEW ENGLAND COAST.

OBVIOUSLY...OUR GREATEST CHANCE FOR MEASURABLE SNOW WILL BE
MONDAY...SO WE HAVE FORECAST AREA-WIDE CHC POPS AT UNDER 45 PERCENT.
THE GFS PASSES SIGNIFICANT QPFS FOR SNOW JUST TO THE SOUTH AND EAST
OF OUR ZONES.  NOT YET CONFIDENT ABOUT THIS SYSTEM AS IT DOESN`T
EVEN EXIST YET AND THE ECMWF DOESN`T EVEN FORM IT IN ITS LATEST RUN.
HPC APPEARS CONFIDENT OF ITS FORMATION...BUT MAINTAINS AN EASTWARD
TRACK OFF THE MID-ATLANTIC COAST...LIKELY A COMPROMISE OF SORTS.
WHAT WE WILL PROBABLY END UP WITH IS A RATHER HO-HUM...BUT
SEASONABLY COLD... PERIOD...WITH A MINIMAL AMOUNTS OF SNOW...BUT
PERHAPS SLIGHTLY MORE SIGNIFICANT SNOW WELL SOUTH OF ALBANY.

WHILE DAYTIME WINDS ARE EXPECTED TO BLOW IN THE 10 TO 15 MPH RANGE
EACH DAY...PLUS SOME GUSTS...THE GOOD NEWS IS THERE PROBABLY WON`T
BE A SHORTAGE OF SUNSHINE ON EITHER SIDE OF THE SYSTEM...ESPECIALLY
FARTHER AWAY FROM LAKE ONTARIO.  DAYTIME HIGH TEMPERATURES WON`T
VARY TOO MUCH DAY TO DAY...WITH READINGS MAINLY IN THE MID 20S TO
MID 30S RANGE.  LOWS WILL ALSO VARY LITTLE...IN THE SINGLE DIGITS
AND TEENS.  NORMAL HIGHS AND LOWS AT ALBANY ON VALENTINE`S DAY ARE
34 DEGREES AND 15 DEGREES...RESPECTIVELY.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
VFR CONDITIONS TO START OFF.  HAVE LOWERING CLOUDS AND SNOW MOVING
IN...WITH MVFR ARRIVING FROM SOUTH TO NORTH BETWEEN 06Z AND 10Z...IN
ASSOCIATION WITH AN APPROACHING BROAD MID-ATLANTIC SURFACE LOW.
EXPECTING IFR IN PLACE BY DAYBREAK AT GFL AND ALB WITH SNOW WELL
UNDERWAY...BUT CLOSER TO 15Z AT GFL.  A BRIEF BURST OF HEAVY SNOW IN
A DEFORMATION ZONE COULD BRING POU DOWN BRIEFLY TO VLIFR.  HAVE AN
HOUR OF IT IN THE MID-AFTERNOON.  THINGS BEGIN TO SLOWLY IMPROVE AS
THE SYSTEM LIFTS OUT...BUT IFR CONDITIONS STILL IN PLAY AT THE END
OF THE TAF PERIOD.

WINDS WILL BE NEARLY CALM OVERNIGHT...WITH A NORTHERLY SURFACE FLOW
INCREASING AS THE STORM INTENSIFIES AND MOVES OFF THE DELMARVA
PENINSULA.  SUSTAINED WINDS FROM 10 TO 15 KNOTS...WITH GUSTS TO 20
KNOTS OR MORE ARE LIKELY DURING THE IFR PORTION OF THE EVENT.  WINDS
AT THE 2000-FOOT LEVEL START OFF VERY LIGHT...BUT WILL ALSO
INCREASE...TO 25 TO 35 KNOTS BY THE END OF THE TAF PERIOD.

OUTLOOK...
WED NGT...-SN TAPERING...IMPROVING TO VFR.
THU-SUN...VFR...NO SIG WX.  SLGT CHC --SN SATURDAY.
-- End Changed Discussion --

&&

.HYDROLOGY...
NO HYDRO PROBLEMS ANTICIPATED THIS WEEK. ANY PRECIPITATION THAT
OCCURS OVER THE REGION WILL COME IN THE FORM OF SNOW. ICE WILL
CONTINUE TO INCREASE ON MAIN STEM RIVERS...STREAMS AND LAKES.

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...WINTER STORM WARNING FROM 5 AM WEDNESDAY TO 1 AM EST THURSDAY
     FOR CTZ001-013.
NY...WINTER STORM WARNING FROM 5 AM WEDNESDAY TO 1 AM EST THURSDAY
     FOR NYZ058>061-063>066.
     WINTER WEATHER ADVISORY FROM 5 AM WEDNESDAY TO 1 AM EST
     THURSDAY FOR NYZ038>040-047>054-082.
MA...WINTER STORM WARNING FROM 5 AM WEDNESDAY TO 1 AM EST THURSDAY
     FOR MAZ001-025.
VT...WINTER WEATHER ADVISORY FROM 5 AM WEDNESDAY TO 1 AM EST
     THURSDAY FOR VTZ013>015.

&&

$$
SYNOPSIS...FRUGIS/HWJIV
NEAR TERM...FRUGIS/HWJIV
SHORT TERM...HWJIV
LONG TERM...ELH
AVIATION...ELH
HYDROLOGY...SND