February 29, 2012 Forecast Discussion

000
FXUS61 KALY 292136
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
436 PM EST WED FEB 29 2012

.SYNOPSIS…
A COMPLEX STORM SYSTEM MOVING ACROSS THE GREAT LAKES REGION WILL
CONTINUE TO IMPACT EASTERN NEW YORK AND WESTERN NEW ENGLAND TONIGHT
THROUGH THURSDAY. THE WARM FRONT ASSOCIATED WITH THE STORM SYSTEM
WILL CONTINUE TO BRING SNOW INTO THE EVENING…BEFORE TRANSITIONING
TO A WINTRY MIX ESPECIALLY SOUTH OF THE CAPITAL REGION TONIGHT INTO
EARLY THURSDAY. ADDITIONAL SNOWFALL WILL OCCUR ON THURSDAY
ESPECIALLY FROM THE CAPITAL REGION NORTHWARD…AS THE COMPLEX DOUBLE
BARREL LOW PRESSURE SYSTEM SLOWLY MOVES EAST OF NEW ENGLAND BY
THURSDAY NIGHT.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/…
AS OF 430 PM…ONE CHANGE TO WINTER WEATHER HEADLINES IS NORTHERN
LITCHFIELD UPGRADED TO WINTER STORM WARNING BASED ON EXPECTED
COMBINED SNOW/SLEET/FREEZING RAIN THRESHOLDS BEING MET. NO OTHER
CHANGES TO HEADLINES AT THIS TIME. DID RAISE SNOWFALL AMOUNTS
SOMEWHAT BASED ON OVERALL COLDER TRENDS AND LESS
MIX/ICE…ESPECIALLY FROM THE CAPITAL REGION AND BERKSHIRES
NORTHWARD.

PHASE 1 OF THE WINTER STORM IS WELL UNDERWAY…WITH
SNOW HAVING ENVELOPED THE ENTIRE AREA THIS AFTERNOON. THE BEST RADAR
RETURNS ARE CURRENTLY FROM THE HUDSON RIVER VALLEY EASTWARD INTO
WESTERN NEW ENGLAND. A NARROW MESOSCALE BAND HAS SET UP FROM THE
CAPITAL REGION SOUTHEAST THROUGH PORTIONS OF THE TACONICS AND
BERKSHIRES. SNOWFALL RATES OF 1-2" PER HOUR OCCURRING WITHIN THIS
BAND BUT IT IS MOVING.

THERE HAS BEEN A WEAKENING TREND TO THE PRECIP ACROSS WESTERN
AREAS…AS COLDER CLOUD TOPS ARE LOST DUE TO A DRY WEDGE ALOFT
MOVING IN FROM WESTERN AND CENTRAL NY. THIS TREND WILL LIKELY
CONTINUE INTO THE EVENING…WITH A GRADUAL LIGHTENING OF THE
SNOWFALL FROM WEST TO EAST. THE EVENING COMMUTE STILL LOOKS RATHER
MESSY FROM THE CAPITAL REGION EASTWARD…BUT PRECIP SHOULD TEND TO
BECOME MORE INTERMITTENT LATER THIS EVENING. WARMER AIR ALOFT MOVING
INTO THE SOUTHERN AREAS…WITH SLEET AND/OR FREEZING RAIN/PLAIN RAIN
STARTING TO MIX IN EARLY THIS EVENING. AS WE LOSE COLDER CLOUD TOPS
THERE COULD BE SOME SLEET MIXING IN FOR CENTRAL AREAS LATER THIS
EVENING AS WELL.

OVERNIGHT THE FORECAST BECOMES MORE COMPLICATED ONCE AGAIN. ONCE THE
DRY WEDGE ALOFT PASSES THROUGH…ADDITIONAL CLOUD TOP COOLING IS
EXPECTED AS MID/HIGH LEVEL CLOUDS FROM DEVELOPING CONVECTION ACROSS
THE OH/PENN/WV/VA AREA MOVE OVERHEAD WHILE SECONDARY CYCLOGENESIS
OCCURS NEAR THE NEW JERSEY COAST. THE SECONDARY DEVELOPMENT IS
CRUCIAL…SINCE IT WILL CONTINUE TO RESULT IN SUBSTANTIAL LOW LEVEL
BAROCLINICITY JUST TO THE SOUTH OF OUR AREA…WITH HIGH PRESSURE TO
THE NORTHEAST PROVIDING THE LOW LEVEL COLD AIR FEED.

SO…THE NAM/GFS/ECMWF ALL SHOWING MORE ORGANIZED AND WIDESPREAD
PRECIP RE-DEVELOPING AFTER MIDNIGHT ACROSS THE AREA. THIS WILL LEAD
TO ADDITIONAL ACCUMULATING SNOW ACROSS NORTHERN AND CENTRAL
AREAS…WITH SLEET/FREEZING RAIN/PLAIN RAIN TO THE SOUTH. SLEET IS
EXPECTED TO MIX IN AGAIN AROUND THE CAPITAL REGION/MOHAWK
VALLEY/BERKSHIRES…HOWEVER THE MAGNITUDE OF THE WARM NOSE ALOFT IS
NOW EXPECTED TO BE COLDER AND THUS LESS OF A MIX. ONLY AREA OF REAL
CONCERN FOR SEVERAL HOURS OF ICING DUE TO FREEZING RAIN WILL BE
ACROSS THE EASTERN CATSKILLS AND NORTHERN LITCHFIELD CT.

TEMPS WILL NOT MOVE MUCH OVERNIGHT…WITH POSSIBLE SLIGHT GRADUAL
WARMING BY A FEW DEGREES.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/…
BY THURSDAY MORNING…THE SECONDARY LOW WILL BE MOVING OFFSHORE
SOUTH OF LONG ISLAND…WHILE THE CLOSED PRIMARY/UPPER LOW WILL BE ON
OUR DOORSTEP…CROSSING THE GREAT LAKES. LOW LEVEL SOUTHEAST FLOW
WILL PERSIST OVER THE MUCH OF THE AREA THROUGH THE MORNING…WITH
MOISTURE FETCH OFF THE ATLANTIC CONTINUING.

ANY MIXED PRECIP IS EXPECTED TO CHANGE TO MORE OF A RAIN/SNOW REGIME
DUE TO MID LEVEL COOLING SUBSTANTIALLY AS UPPER TROF/CLOSED LOW
MOVES OVERHEAD. MODEL CONSENSUS HAS TRENDED TOWARD A MORE SOUTHERLY
TRACK FOR THE UPPER LOW…WHICH TAKES THE CENTER RIGHT OVER THE
NORTHERN HALF OF THE AREA. QG LIFT FROM CYCLONIC VORTICITY ADVECTION
WILL BE QUITE PRONOUNCED FROM AROUND MID MORNING THURSDAY THROUGH
THE AFTERNOON HOURS. TEMPS PROFILES WILL BE COLD ENOUGH FOR SNOW FOR
MUCH OF THE AREA…WITH RAIN/SNOW MIX IN VALLEY LOCATIONS SOUTH OF
THE CAPITAL REGION. SO ADDITIONAL SNOW ACCUMULATIONS ARE EXPECTED
WITH THE GREATEST AMOUNTS ACROSS THE WESTERN/SOUTHERN ADIRONDACKS
AND SOUTHERN VERMONT/NORTHERN BERKSHIRES.

WITH MORE SNOW NOW EXPECTED FOR THURSDAY DUE TO THE MORE SOUTHERLY
TRACK OF THE UPPER LOW…STORM TOTAL SNOWFALL AMOUNTS HAVE BEEN
RAISED ACROSS THE NORTHERN 2/3 OF THE AREA. NOW EXPECTING STORM
TOTALS OF 5-12" FOR THE EASTERN CATSKILLS NORTHEAST THROUGH THE
CAPITAL REGION AND NORTHERN/CENTRAL TACONICS AND UPPER HUDSON
VALLEY. HIGHER AMOUNTS OF 8-16" EXPECTED FOR THE WESTERN/SOUTHERN
ADIRONDACKS…SOUTHERN VERMONT AND BERKSHIRES. STORM TOTAL SNOW
GRAPHICS HAVE BEEN POSTED TO OUR WEBSITE.

SNOW SHOULD GRADUALLY TAPER OFF THURSDAY EVENING AS THE PRIMARY LOW
PULLS AWAY AND WEAK RIDGING ALOFT BUILDS IN.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/…
A RATHER TRANQUIL END TO THE WEEK AS THE MID WEEK STORM DEPARTS WELL
OFF THE NEW ENGLAND COAST AND THE NEXT STORM DEVELOPING OVER THE MID
MISSISSIPPI RIVER AND OHIO VALLEYS.

A STRONG SURGE OF WARM ADVECTION IS FORECAST TO QUICKLY MOVE ACROSS
THE REGION FRIDAY INTO FRIDAY NIGHT. THE MOISTURE TRANSPORT WILL
ALSO INCREASE RATHER QUICKLY WITH THE CHANCE FOR PRECIPITATION
DEVELOPING FROM SOUTHWEST TO NORTHEAST. BOUNDARY LAYER TEMPS FOR
MOST OF THE REGION ARE EXPECTED TO BE ABOVE FREEZING.
HOWEVER…THERE WILL BE LOCATIONS WITH AT OR BELOW FREEZING
TEMPERATURES WITH THE POTENTIAL FOR EITHER SLEET OR A LITTLE
FREEZING RAIN. WARMER AIR WILL EVENTUALLY ERODE THE COLDER SURFACE
TEMPERATURES WITH MAINLY RAIN EXPECTED LATE AT NIGHT AND INTO
SATURDAY MORNING. IN FACT…THE LOW LEVEL JET MAGNITUDES INCREASE
TO VALUES GREATER THAN 50KTS. WHILE THIS LATEST NCEP MODEL SUITE
SHOWALTER VALUES ARE A BIT MORE POSITIVE…WE CAN NOT TOTALLY RULE
OUT A CLAP OF THUNDER WITHIN THE WARM SECTOR AND AHEAD OF THE FROPA.

AS FOR THE TIMING OF THE FROPA…SEEMS THIS WILL OCCUR BEFORE NOON
SATURDAY. WITH 850MB TEMPS PROGGED TO CLIMB WELL INTO THE HIGH
SINGLE DIGITS…VALLEY TEMPERATURES COULD CLIMB WELL INTO THE 40S
WITH SOME LOWER 50S POSSIBLE FOR THE MID HUDSON VALLEY AND SOUTHERN
LITCHFIELD COUNTY.

A REGION OF SUBSIDENCE AND DRIER AIR ARE EXPECTED FOR SATURDAY NIGHT
INTO THE START OF SUNDAY AS MAIN FRONT WAS OFF THE ATLANTIC COAST
AND MAIN UPPER TROF AXIS REMAINS OVER THE HEART OF THE GREAT LAKES
REGION. THIS AFOREMENTIONED TROF AXIS IS EXPECTED TO MIGRATE EAST
SUNDAY INTO MONDAY WITH AN INCREASE IN THE CYCLONIC FLOW AND
MOISTURE FOR A SLIGHT CHANCE FOR SOME LIGHT RA/SN SHOWER ACTIVITY.

MONDAY NIGHT INTO TUESDAY…LARGE CONSENSUS THAT HIGH PRESSURE WILL
EXPAND ACROSS THE EASTERN CONUS WITH CLEARING SKIES AND TEMPERATURES
CLIMBING AT OR ABOVE NORMAL.

&&

.AVIATION /22Z WEDNESDAY THROUGH MONDAY/…
MAINLY VFR CONDITIONS ARE EXPECTED THIS MORNING WITH A RAPID
DETERIORATION TO IFR/LIFR CONDITIONS BETWEEN 18Z AND 19Z AS PCPN
SHIELD ASSOCIATED WITH THE LOW PRESSURE SYSTEM MOVING INTO THE
GREAT LAKES ARRIVES LIKE A WALL. HAVE SOME LIGHT SNOW IMPACTING
KGFL EARLY THIS MORNING AHEAD OF THE MAIN PRECIPITATION SHIELD
WITH MVFR-IFR CONDITIONS EXPECTED WHEN IT SNOWS.

IFR/LIFR CONDITIONS EXPECTED TO ARRIVE AT 18Z-19Z WITH THE ONSET OF
SNOW. THE SNOW WILL CONTINUE HEAVY AT TIMES AT KGFL AND KALB THROUGH
THE END OF THE TAF PERIOD AT 12Z THU…ALTHOUGH SOME SLEET IS
EXPECTED TO MIX IN AT KALB AT OR AROUND MIDNIGHT. AT KPOU PTYPE IS
EXPECTED TO MIX WITH OR CHANGE TO SLEET AROUND 22Z AND THEN RAIN
AROUND 00Z.

LIGHT AND VARIABLE WINDS WILL BECOME NE-E AT 4-8 KTS MID MORNING
THROUGH THE END OF THE TAF PERIOD AT 12Z THU.

OUTLOOK…
THU…MVFR/IFR. SNOW AT KGFL. RAIN/SNOW AT KALB. RAIN AT KPOU.
THU NIGHT…IMPROVING TO VFR. CHC -SHSN IN THE EVNG.
FRI…VFR. NO SIG WX.
FRI NIGHT…VFR/MVFR. CHC -RA/-SN.
SAT…MVFR WITH CHC IFR. RAIN SHOWERS LIKELY.
SAT NIGHT…VFR/MVFR. CHC -SHRA/-SHSN.
SUN…VFR. WINDY.

&&

.HYDROLOGY…
NO HYDRO PROBLEMS ARE EXPECTED FOR THE NEXT 5 DAYS ON THE MAIN STEM
RIVERS. SOME HYDRO GAGES ARE STILL BEING IMPACTED BY ICE FROM THE
MOHAWK RIVER VALLEY NORTHWARD INTO THE ADIRONDACKS.

A HEAVY PRECIPITATION EVENT IS ONGOING AND WILL CONTINUE THROUGH
THURSDAY WITH TOTAL QPF AROUND AN INCH TO AN INCH AND A QUARTER.
THERE COULD BE SOME LOCALLY HIGHER AMOUNTS. A LARGE PORTION OF THE
PRECIPITATION WILL FALL AS SNOW AND SLEET…MIXING WITH SOME RAIN OR
FREEZING RAIN ESPECIALLY ACROSS AREAS SOUTH OF THE CAPITAL REGION.
SEVERAL INCHES OF SNOW AND SLEET ARE EXPECTED FOR MUCH OF THE
REGION…SO NOT MUCH RIVER RESPONSE IS ANTICIPATED EXCEPT FOR SOME
MINOR RISES ACROSS SOUTHERN AREAS WHERE SOME OF THE PRECIP WILL FALL
AS RAIN AND THERE WILL SLIGHT RUNOFF.

DRY WEATHER WILL BRIEFLY RETURN ON FRIDAY…BEFORE ANOTHER SYSTEM
BRINGS A ROUND OF RAIN AND MIXED PRECIP TO THE REGION FRIDAY NIGHT
INTO SATURDAY. THERE COULD BE SOME DECENT SNOW MELT AS TEMPERATURES
SOAR ABOVE NORMAL…BUT THERE IS ONLY A NARROW WINDOW FOR WARMER
TEMPERATURES AS IT IS UNCLEAR HOW MUCH MELT/RUNOFF WOULD OCCUR.
PRECIP AMOUNTS AROUND ONE QUARTER TO ONE HALF INCH ARE EXPECTED.
COMBINED WITH THE SNOW MELT…THERE WILL LIKELY BE RISES ON RIVERS
BUT FLOODING IS NOT ANTICIPATED AT THIS TIME.

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.

&&

.CLIMATE…
LEAST SNOWIEST DEC-JAN-FEB FOR ALBANY NY
YEARS OF RECORD: 1884-2012
1) 8.8 INCHES 2011-12 (THROUGH 2/28)
2) 10.9 INCHES 1936-37
3) 11.7 INCHES 1912-13
4) 13.8 INCHES 1911-12
5) 14.2 INCHES 1988-89
6) 16.3 INCHES 1931-32
7) 16.6 INCHES 1979-80
8) 17.0 INCHES 1954-55
9) 17.1 INCHES 1918-19
17.1 INCHES 1889-90
10) 17.3 INCHES 1910-11

LEAST SNOWIEST SEASONS FOR ALBANY NY
YEARS OF RECORD: 1884-2012
1) 13.8 INCHES 1912-13
2) 14.2 INCHES 2011-12 (THROUGH FEB 28TH)
3) 19.0 INCHES 1988-89
4) 24.8 INCHES 1929-30
5) 26.7 INCHES 1918-19
6) 27.4 INCHES 1979-80
7) 28.1 INCHES 1889-90
8) 28.4 INCHES 1936-37
9) 28.7 INCHES 1990-91
28.7 INCHES 1914-15
11) 28.9 INCHES 1896-97

&&

.ALY WATCHES/WARNINGS/ADVISORIES…
CT…WINTER STORM WARNING UNTIL 6 PM EST THURSDAY FOR CTZ001.
WINTER WEATHER ADVISORY UNTIL NOON EST THURSDAY FOR CTZ013.
NY…WINTER STORM WARNING UNTIL 6 PM EST THURSDAY FOR NYZ032-033-
038>043-047>054-058>061-063-082>084.
WINTER WEATHER ADVISORY UNTIL NOON EST THURSDAY FOR NYZ064>066.
MA…WINTER STORM WARNING UNTIL 6 PM EST THURSDAY FOR MAZ001-025.
VT…WINTER STORM WARNING UNTIL 6 PM EST THURSDAY FOR VTZ013>015.

&&

$$
SYNOPSIS…JPV
NEAR TERM…JPV
SHORT TERM…JPV
LONG TERM…BGM
AVIATION…KGM
HYDROLOGY…JPV/WASULA
CLIMATE…IAA

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