December 9, 2014 Forecast Discussion

000
FXUS61 KALY 092215 RRA
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
1240 PM EST TUE DEC 9 2014

.SYNOPSIS…
A SLOW MOVING COASTAL STORM WILL BRING A VARIETY OF WINTER WEATHER
TO THE REGION INTO TONIGHT. WHILE MANY VALLEY AND EASTERN AREAS WILL
HAVE MAINLY RAIN WITH SOME MIXED PRECIPITATION TONIGHT…THE
PRECIPITATION WILL BE SNOW OR A WINTRY MIXED ACROSS THE CATSKILLS
AND ADIRONDACKS…WITH A MODERATE TO HEAVY ACCUMULATION POSSIBLE IN
THESE HIGH TERRAIN AREAS. WITH THE STORM REMAINING CLOSE TO THE
REGION…SOME ADDITIONAL RAIN AND SNOW WILL OCCUR WEDNESDAY INTO
THURSDAY AS WELL…WITH SOME ADDITIONAL SNOW ACCUMULATION POSSIBLE.

&&

.NEAR TERM /THROUGH TONIGHT/…
AS OF 445 PM…AN EXTREMELY HEAVY BAND OF PCPN CURRENTLY MOVING
THROUGH THE HUDSON VALLEY. DYNAMIC COOLING ASSOCIATED WITH THIS
HEAVY BAND WILL CAUSE RAIN TO MIX WITH OR SNOW FOR A BRIEF TIME THIS
EVENING IN THE HUDSON VALLEY FROM THE CAPITAL DISTRICT NORTH. TO THE
WEST…IN THE CATSKILLS AND MOHAWK VALLEY MIXED PCPN WILL ALSO
CHANGE OR HAS ALREADY CHANGED TO MAINLY SNOW THIS EVENING.

WINTER STORM WARNINGS CONTINUE FROM THE EASTERN CATSKILLS TO THE
MOHAWK VALLEY AND EASTERN SOUTHERN ADIRONDACKS. WINTER WEATHER
ADVISORIES CONTINUE FROM THE SARATOGA/GLENS FALLS AREA EASTWARD TO
SOUTHERN VERMONT AND NORTHERN BERKSHIRE. HOWEVER…WILL BE UPGRADING
WESTERN WINDHAM TO A WINTER STORM WARNING VERY SHORTLY.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/…
A NEARLY VERTICALLY STACKED LOW OVER NEW ENGLAND WILL KEEP OUR
WEATHER UNSETTLED THROUGH THE SHORT TERM PERIOD.

WHILE DIFFICULT TO ASCERTAIN WHAT WAVE/S/ WILL TRIGGER ADDITIONAL
PRECIPITATION…MOISTURE WILL WRAP IN OFF THE ATLANTIC TO KEEP THE
HIGH PROBABILITIES IN THE FORECAST. THE BEST LOCATIONS WILL BE
ALONG THE I90 CORRIDOR AND POINTS NORTHWARD. AS FOR THERMAL
PROFILES…WE WILL BE COOLING DOWN THE COLUMN WHERE MOST OF THIS
PRECIPITATION WILL BE IN THE FORM OF SNOW. THERE WILL BE SOME
RAIN/SNOW MIXTURE INTO THE VALLEY LOCATIONS DURING THE LATE MORNING
INTO THE MID AFTERNOON HOURS. THE BEST CHANCE FOR ADDITIONAL
ACCUMULATIONS WILL BE INTO THE HIGHER TERRAIN. AS FOR THE
SPECIFIC…

WEDNESDAY…LATEST TRENDS IN THE MODEL GUIDANCE POINT TOWARD A MORE
SIGNIFICANT SURGE OF MOISTURE OFF THE ATLANTIC AS THE MAIN UPPER LOW
REMAINS JUST OFF THE JERSEY SHORE. MOISTURE ADVECTION AND HIGHER
THETA-E /TROWAL/ BACK INTO PORTIONS OF EASTERN NEW YORK AND WESTERN
NEW ENGLAND. SPECIFIC HUMIDITIES REMAIN RATHER HIGH OF 3-4 G/KG SO
WHERE IT DOES SNOW…WE COULD SEE ADDITIONAL ACCUMULATIONS OF SNOW.
PER THE LATEST NCEP MODEL SUITE AND 00Z ECMWF…THIS SEEMS TO LINE
UP FOR OUR NORTHERN HALF OF THE CWFA. ADDITIONAL FINE TUNING WILL
TAKE PLACE AS PER CSTAR RESEARCH…THESE UPPER LOWS ARE QUITE
PROBLEMATIC WITH PROVIDING SPECIFICS WHERE THE HEAVIER QPF WILL FALL.

THURSDAY…AS THE LOW FILLS AND FURTHER REDUCES THE
BAROCLINICITY…THE PRECIP INTENSITY AND AMOUNTS WILL DIMINISH. SO
ADDITIONAL ACCUMULATIONS SHOULD BE RATHER LIGHT THROUGH THE DAY WITH
JUST A COUPLE MORE INCHES OF SNOW…MAINLY INTO THE TERRAIN.

THURSDAY NIGHT…WHILE THE UPPER LOW BEGINS TO SLOWLY MIGRATE
EASTWARD…ITS INFLUENCES WILL CONTINUE ACROSS THE REGION. THIS
WILL RESULT IN CHC-SCT SNOW PROBABILITIES WITH ADDITIONAL LIGHT
ACCUMULATIONS THROUGHOUT THE REGION AS TEMPERATURES WILL BE BELOW
FREEZING.

WE WILL USE A BLENDED APPROACH TO THE MOS TEMPERATURES AS THEY WERE
FAIRLY CLOSE IN VALUES.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/…
GUIDANCE IS IN GENERAL AGREEMENT THAT THE LONGWAVE PATTERN WILL
AMPLIFY BY THE END OF THE WEEK WITH THE STACKED LOW PRESSURE SYSTEM
CENTERED OVER NEW ENGLAND…RIDGING OVER THE CENTRAL CONUS AND A
TROUGH MOVING IN ON THE WEST COAST. ADDITIONAL SHORT WAVE ENERGY
MOVING THROUGH THE WEST COAST TROUGH IS EXPECTED TO RESULT IN AN
UPPER LOW CUTTING OFF OVER THE SOUTHERN PLAINS OVER THE WEEKEND
WHILE NORTHERN STREAM ENERGY MOVING EASTWARD ACROSS CANADA WILL
DAMPEN THE RIDGE AS IT SHIFTS EASTWARD TO THE EAST COAST.

THE STACKED LOW PRESSURE SYSTEM THAT HAS BEEN PLAGUING THE REGION
WILL FINALLY BEGIN TO SLOWLY MOVE AWAY AS WE HEAD INTO THE WEEKEND.
WE SHOULD STILL BE DEALING WITH SOME RESIDUAL SHOWERS…MAINLY
SNOW…AS WE CLOSE OUT THE WORK WEEK AND HEAD INTO THE WEEKEND.

THE INFLUENCE OF THE STACKED LOW WILL LESSEN AS THE SYSTEM MOVES
GRADUALLY OFF TO THE SOUTHEAST WITH RIDGING BUILDING IN FROM THE
WEST. LOOKS LIKE WE SHOULD EXPERIENCE A PERIOD OF DRY WEATHER OVER
MOST OF THE THE WEEKEND INTO EARLY NEXT WEEK.

SEASONAL TEMPERATURES FOR MID DECEMBER ARE EXPECTED…WITH HIGHS
GENERALLY IN THE 30S WITH LOWS MAINLY IN THE 20S.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/…
A SIGNIFICANT COASTAL STORM WITH MULTIPLE PRECIPITATION TYPES WILL
CONTINUE TO IMPACT THE TAF SITES WITH IFR-MVFR CONDITIONS.

MAINLY IFR CEILINGS ARE EXPECTED THROUGH THE REMAINDER OF THE TAF
PERIOD. RAIN SHOULD CONTINUE UNTIL 03Z-08Z…WITH SLEET AND SNOW
MIXING IN AT TIMES. A MIXTURE OF RAIN AND SNOW IS EXPECTED AT THE
TAF SITES MUCH OF THE OVERNIGHT INTO WEDNESDAY MORNING WITH A
TRANSITION TO SNOW OCCURRING WEDNESDAY MORNING INTO THE AFTERNOON.

WINDS WILL BE OUT OF THE NORTH AT 10 TO 15 KNOTS WITH OCCASIONAL
GUSTS INTO INTO THE 20 KNOTS.

OUTLOOK…
WED NIGHT: HIGH OPERATIONAL IMPACT. BREEZY. DEFINITE SN.
THU: HIGH OPERATIONAL IMPACT. LIKELY SN.
THU NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SN.
FRI: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA…SHSN.
FRI NIGHT-SAT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
SAT NIGHT-SUN: NO OPERATIONAL IMPACT. NO SIG WX.

&&

.HYDROLOGY…
A FLOOD WATCH REMAINS IN EFFECT FOR LITCHFIELD COUNTY
CONNECTICUT…DUTCHESS COUNTY NEW YORK AND EASTERN ULSTER COUNTY
NEW YORK…FOR THIS MORNING THROUGH TONIGHT.

A COASTAL STORM WILL BRING WIDESPREAD PRECIPITATION TO THE AREA
FOR TODAY INTO TONIGHT. FOR NORTHWESTERN AND HIGH TERRAIN
AREAS…THIS PRECIPITATION WILL FALL PRIMARY AS SNOW OR A WINTRY
MIX. MEANWHILE…ACROSS SOUTHERN AND VALLEY AREAS…PRECIP WILL
BEGIN AS A PERIOD OF SNOW OR A WINTRY MIX AND TRANSITION TO RAIN.
TOTAL LIQUID EQUIVALENT VALUES WILL BE 0.50 OVER THE WESTERN
ADIRONDACKS TO NEARLY 2.00 INCHES OVER WESTERN NEW ENGLAND. WITH
MUCH OF THIS FALLING AS RAINFALL OVER LITCHFIELD COUNTY AND THE
MID HUDSON VALLEY…THERE WILL BE A LOT OF RUNOFF…ESPECIALLY
DURING LATE THIS MORNING THROUGH EARLY THIS EVENING WHEN PRECIP
WILL BE HEAVIEST. THIS RAINFALL MAY LEAD TO MINOR FLOODING OF POOR
DRAINAGE AND LOW LYING AREAS…ESPECIALLY IN AREAS WHERE THE
GROUND IS FROZEN. RISES ON RIVERS AND STREAMS ARE LIKELY…AND
MINOR FLOODING CANNOT BE RULED OUT ON THE HOUSATONIC RIVER AND
IT/S TRIBUTARIES IN NW CT.

IN ADDITION…THE STRONG COASTAL LOW IS ALLOWING FOR SOME TIDAL
FLOODING ALONG COASTAL AREAS…AND THIS COULD CAUSE A BACKUP OF
WATER ON THE HUDSON RIVER. THIS COULD LEAD TO MINOR FLOODING
DURING TIMES OF HIGH TIDE IN THE POUGHKEEPSIE AREA THIS AFTERNOON.

SOME ADDITIONAL PRECIPITATION…MAINLY IN THE FORM OF SNOW…IS
POSSIBLE FOR WEDNESDAY INTO THURSDAY…BUT AMOUNTS ARE EXPECTED TO
BE LIGHT IN AREAS THAT SEE THE HEAVIEST LIQUID PRECIP TODAY. THIS
SHOULD ALLOW WATER LEVELS TO RECEDE SLOWLY OVER THE NEXT FEW DAYS.

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 LATE TONIGHT FOR CTZ001-013.
NY…WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR NYZ032-033-
038>040-042-043-047-048-051-058-063-082.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NYZ041-
083-084.
FLOOD WATCH THROUGH LATE TONIGHT FOR NYZ064>066.
MA…WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
MAZ001.
VT…WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
VTZ013>015.

&&

$$
SYNOPSIS…GJM
NEAR TERM…GJM
SHORT TERM…TAW/BGM
LONG TERM…IAA
AVIATION…IRL
HYDROLOGY…FRUGIS

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