January 28, 2013 Forecast Discussion

000
FXUS61 KALY 281421
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
921 AM EST MON JAN 28 2013

.SYNOPSIS…
A WARM FRONT WILL APPROACH FROM FROM THE OHIO VALLEY AND GREAT
LAKES REGION TODAY…BRINGING A WINTRY MIX OF PRECIPITATION. THIS
FRONTAL BOUNDARY WILL BECOME STATIONARY ACROSS THE AREA TONIGHT INTO
TUESDAY…BEFORE LIFTING NORTHWARD ON WEDNESDAY BRINGING MUCH WARMER
TEMPERATURES. A STRONG COLD FRONT WILL PASS THROUGH THE AREA
WEDNESDAY NIGHT…FOLLOWED BY MUCH COLDER AND BLUSTERY CONDITIONS
FOR THURSDAY AND FRIDAY.

&&

.NEAR TERM /UNTIL 7 PM THIS EVENING/…
…WINTER WEATHER ADVISORIES CONTINUE FOR THE ENTIRE AREA THROUGH
TONIGHT…

RADAR AND LATEST 12Z SOUNDINGS SHOW THE SNOW SHOULD BE REACHING
THE GROUND OVER MOST OF THE FORECAST AREA WELL BEFORE NOON. SNOW
HAS CHANGED TO FREEZING RAIN AT ELMIRA…AND AS WARM AIR STREAMS
IN ALOFT….THE CHANGEOVER SHOULD OCCUR THIS AFTERNOON AND THIS
EVENING…AS PRECIPITATION TAPERS OFF. CURRENT PREDICTED SNOW
TOTALS LOOK GOOD AND OF COURSE WILL DEPEND ON WHEN THE SNOW
TRANSITIONS TO SLEET AND FREEZING RAIN. SINCE PRECIPITATION SHOULD
TAPER OFF AS IT CHANGES OVER…ANY ACCUMULATIONS OF SLEET AND
FREEZING RAIN SHOULD BE LIGHT. HAVE SHAVED A DEGREE OR SO OFF THE
HIGH TEMPERATURES FOR TODAY…AND HIGHS SHOULD OCCUR VERY LATE IN
THE AFTERNOON. PREV AFD DESCRIBES THE PROCESSES AND DYNAMICS
BEHIND THE UPCOMING EVENT WELL AND IS BELOW.

PREV AFD BELOW…

PRECIPITATION GETTING CLOSE TO THE AREA THIS MORNING…WITH SNOW
REACHING THE GROUND AS FAR EAST AS CENTRAL NY AND MOST OF PA. IT
WILL STILL TAKE SOME TIME TO SATURATE THE COLUMN ACROSS OUR AREA
WITH A SIGNIFICANT DRY WEDGE IN THE LOWEST 5 KFT LOOKING AT THE
KALB SOUNDING…BUT THIS SHOULD OCCUR BY LATER THIS MORNING AS
LARGE SCALE ASCENT INCREASES SIGNIFICANTLY FROM WARM ADVECTION AND
ISENTROPIC LIFT ON THE 290K SURFACE ASSOCIATED WITH THE
APPROACHING WARM FRONT. TIMING OF ONSET OF SNOW LOOKS TO BE NEAR
THE END OF OR JUST AFTER THE BULK OF THE MORNING COMMUTE
TIME…ESPECIALLY FOR AREAS FROM THE HUDSON VALLEY EASTWARD. WHEN
THE PRECIP ARRIVES…IT WILL LIKELY BE SNOW WITH A MORE GRADUAL
CHANGE-OVER TO SLEET AND FREEZING RAIN.

THERMAL PROFILES AND FORECAST SOUNDINGS FROM THE LATEST 00Z/06Z
GUIDANCE /MAINLY THE NAM/ INDICATE COLDER TEMPERATURES IN THE LOWER
TROPOSPHERE THAN PREVIOUSLY FORECAST FOR MUCH OF TODAY…WITH A WARM
NOSE AROUND 850-800MB GRADUALLY PUSHING IN FROM THE SOUTH AND WEST
DURING THE LATE AFTERNOON OR EARLY EVENING. IN FACT…ARRIVAL OF
WARMER AIR APPEARS TO BE DELAYED ENOUGH SO THAT FROM ROUGHLY THE
CAPITAL DISTRICT AND MOHAWK VALLEY NORTH…A CHANGE-OVER TO FREEZING
RAIN/DRIZZLE MAY OCCUR SOLELY DUE TO LOSING ICE IN THE SATURATED
CLOUD LAYER. FARTHER SOUTH…IT DOES APPEAR THERE WILL BE ENOUGH
WARMING ALOFT MOVING IN FOR A QUICKER CHANGE TO SLEET AND FREEZING
RAIN BEFORE COLDER CLOUD TOPS MOVE AWAY AND MID LEVEL DRYING
OCCURS.

AS A RESULT…HAVE ADJUSTED SNOWFALL ACCUMULATIONS TO ACCOUNT FOR A
LATER CHANGE TO FROZEN PRECIP. HAVE INCREASED SNOWFALL TO AROUND 2
TO 4 INCHES FROM THE MOHAWK VALLEY/CAPITAL DISTRICT NORTHWARD…WITH
EVEN GREATER TOTALS OF 3 TO 6 INCHES FOR MUCH OF THE SOUTHERN
ADIRONDACKS AND LAKE GEORGE AREA. GENERALLY 1 TO 3 INCHES ARE STILL
EXPECTED ACROSS SOUTHERN AREAS.

SURFACE TEMPERATURES WILL ONLY GRADUALLY RISE TODAY WITH THE
PRECIPITATION FALLING THROUGH THE DAY…WITH SUB-FREEZING READINGS
NOW EXPECTED ACROSS THE ENTIRE AREA BUT POSSIBLY REACHING THE LOWER
30S FROM AROUND ALBANY SOUTH IN VALLEY LOCATIONS.

&&

.SHORT TERM /7 PM THIS EVENING THROUGH WEDNESDAY/…
STEADIER ACCUMULATING SNOW/SLEET/FREEZING RAIN WILL START TO WIND
DOWN THIS EVENING…AS BEST LIFT MOVES EAST OF THE AREA AND ICE
NUCLEI IN THE CLOUDS ARE LIKELY TO DIMINISH AS WELL. HOWEVER…THERE
SHOULD BE ENOUGH LOW LEVEL MOISTURE AND WEAK LIFT WITH THE STALLING
FRONTAL BOUNDARY OVER THE REGION TO PRODUCE LIGHT FREEZING RAIN OR
FREEZING DRIZZLE BY LATER IN THE EVENING INTO THE OVERNIGHT HOURS.
SO THE CURRENT WINTER WEATHER ADVISORY CONTINUING THROUGH 7 AM
TUESDAY LOOKS GOOD AT THIS TIME. TEMPERATURES WILL LIKELY REMAIN
STEADY OR ONLY DROP A FEW DEGREES OVERNIGHT…BUT WILL NOT SEE MUCH
MOVEMENT EITHER WAY.

ANY LINGERING FREEZING DRIZZLE SHOULD END BY AROUND SUNRISE
TUESDAY…AS A WEAK RIDGE OF HIGH PRESSURE MOVES IN. HOWEVER…STILL
EXPECTING CLOUD COVER TO LINGER THOUGH AS PLENTY OF RESIDUAL LOW
LEVEL MOISTURE REMAINS AND ALSO THE AFOREMENTIONED FRONTAL BOUNDARY
MAY STILL BE POSITIONED OVER THE AREA DESPITE BECOMING DIFFUSE.
TRICKY FORECAST FOR TEMPERATURES ON TUESDAY…AS VARIOUS SOURCES OF
GUIDANCE NOT IN AGREEMENT ON THE POSITION OF THE FRONT AS WELL AS
CLOUD COVER. WILL GENERALLY SPLIT THE DIFFERENCE OF MET/MAV
GUIDANCE…BUT IN GENERAL BOTH HAVE TRENDED COOLER FOR TUESDAY.

ANOTHER SHOT OF WARM ADVECTION/ISENTROPIC LIFT IS FORECAST TO ARRIVE
TUESDAY AFTERNOON/EVENING. MODELS DO NOT AGREE ON TIMING AND EXTENT
OF PRECIP…AND THERMAL PROFILES ARE CONCERNING FOR SOME OF THE
HIGHER TERRAIN AREAS OF THE ADIRONDACKS AND SOUTHERN VERMONT. SO A
LOW CONFIDENCE FORECAST DURING THIS TIME…ALTHOUGH IT DOES APPEAR
THE BEST CHANCE FOR MEASURABLE PRECIP WILL BE ACROSS THE NORTHERN
AREAS. HAD TO INCLUDE MENTION OF SNOW/SLEET/RAIN MIX FOR SOME OF THE
MOUNTAINS FOR NORTHERN AREAS DUE TO POSSIBLE COOLING.
OTHERWISE…RAIN SHOWERS EXPECTED. TEMPERATURES NOT EXPECTED TO DROP
MUCH TUESDAY NIGHT…ALTHOUGH IT DOES APPEAR TO BE COLDER THAN
PREVIOUS FORECASTS AS SEEN IN MODEL TRENDS.

THE REAL WARM AIR LOOKS TO ARRIVE ON WEDNESDAY…AS THE UPPER LEVEL
PATTERN BECOMES MORE AMPLIFIED AND LOW LEVEL WINDS SHIFT TO MORE OF
A S-SW DIRECTION WITH SPEEDS INCREASING SIGNIFICANTLY. WHILE IT WILL
BE BREEZY…THERE IS UNCERTAINTY FOR HOW MUCH MIXING WILL OCCUR
WITHIN THE S-SW FLOW IN THE WARM SECTOR. CLOUD COVER MAY ALSO BE AN
ISSUE. THE RECORD HIGH FOR ALBANY IS 54 AND THIS COULD BE REACHED.
MIXING WILL NOT BE DEEP ENOUGH TO REALIZE THE +10C TO +12C 850MB
TEMPERATURES…BUT MANY AREAS COULD WARM WELL INTO THE 50S. THIS
WILL ACCELERATE SNOW MELT…EVEN IN THE MOUNTAINS. REFER TO HYDRO
SECTION FOR DETAILS. SHOWERS ARE EXPECTED TO DEVELOP WEDNESDAY
AFTERNOON AHEAD OF A COLD FRONT ADVANCING EASTWARD ACROSS THE GREAT
LAKES.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/…
WILL BE TRANSITIONING BACK TO WINTER WITH THE PASSAGE OF A STRONG
COLD FRONT WEDNESDAY NIGHT. THERE ARE STILL SOME MODEL DIFFERENCES
BRINGING THIS BOUNDARY ACROSS THE REGION. THE ECMWF IS ABOUT 6 HOUR
SLOWER THAN THE GFS BRINGING THE COLDER AIR BACK INTO REGION
WEDNESDAY NIGHT/EARLY THURSDAY. THE GFS IS QUICKER MOVING SHORT WAVE
ENERGY THROUGH THE TROUGH. AT THIS POINT HAVE CONTINUED WITH A
COMPROMISE. SHOWERS WILL ACCOMPANIED THE BOUNDARY AS IT MOVES
THROUGH WITH RAIN CHANGING TO SNOW AFTER MIDNIGHT. LIGHT
ACCUMULATIONS OF SNOW ARE EXPECTED ESPECIALLY TO THE NORTH AND WEST
OF THE CAPITAL DISTRICT AND ACROSS SOUTHERN VERMONT. SOUTHERLY WINDS
WILL SHIFT TO THE WEST WITH THE PASSAGE OF THE FRONT.

THE REGION WILL REMAIN UNDER A LONGWAVE TROUGH THROUGH THE PERIOD AS
IT GETS REINFORCED.

THE PRESSURE GRADIENT WILL BE TIGHT ACROSS THE REGION INTO FRIDAY
AND PARTICULARLY ON THURSDAY WITH GUSTS WELL INTO THE 30S EXPECTED.
ALONG WITH THE BRISK AND GUSTY WINDS TEMPERATURES WILL NOT MUCH
CHANGE THROUGH THE DAY. TEMPERATURES WILL BE BACK TO SEASONABLE
LEVELS ON FRIDAY AND ARE EXPECTED TO PERSIST THROUGH THE WEEKEND.
THE PRESSURE GRADIENT WILL WEAKEN FOR FRIDAY NIGHT THROUGH SATURDAY
NIGHT…HOWEVER ANOTHER BRISK AND GUSTY DAY IS EXPECTED ON SUNDAY.

SHORT WAVE TROUGHS WILL MOVE ACROSS THE REGION WITH ONE EXPECTED ON
FRIDAY AND ANOTHER SUNDAY. THIS ALONG WITH THE CYCLONIC FLOW WILL
KEEP THE THREAT OF SNOW SHOWERS IN THE FORECAST ESPECIALLY FOR THE
AREAS TO THE WEST OF THE HUDSON RIVER VALLEY.

&&

.AVIATION /14Z MONDAY THROUGH FRIDAY/…
CONDITIONS WILL DETERIORATE TODAY ESPECIALLY DURING THE AFTERNOON
AS PRECIPITATION OVERSPREADS THE AREA AHEAD OF AN ADVANCING WARM
FRONT. INITIALLY MVFR CONDITIONS WILL DEVELOP DURING THE MID TO LATE
MORNING THEN QUICKLY DROP TO IFR AS SNOW INITIALLY OVERSPREADS THE
AREA. WARMER AIR WILL WORK ITS WAY IN ALOFT RESULTING IN A WINTRY
MIX IN THE AFTERNOON INCLUDING SLEET AND FREEZING RAIN. THE
PRECIPITATION WILL TRANSITION TO FREEZING DRIZZLE IN THE EVENING AS
THE ATMOSPHERE ALOFT DRIES OUT AND TEMPERATURES AT THE SURFACE
REMAIN AT OF BELOW FREEZING.CHANCES FOR THE FREEZING DRIZZLE WILL
DECREASE OVERNIGHT. WINDS WILL BE VERY LIGHT.

OUTLOOK…
TUE…MVFR/IFR. CHC -SHRA IN THE AFTN.
TUE NIGHT…MVFR/IFR. KGFL…-SHRA LIKELY. KALB/KPSF/KPOU CHC -SHRA.
LLWS POSSIBLE.
WED…MVFR/IFR. CHC -SHRA IN THE AM AND LIKELY IN THE PM.
WED NIGHT…MVFR. -SHRA LIKELY IN THE EVNG CHANGING TO -SHSN AFTER
MIDNIGHT. WINDY.
THU…VFR. CHC SUB-VFR -SHRA/SHSN. WINDY.
FRI…VFR. SCHC -SHSN.

&&

.HYDROLOGY…
NO HYDRO PROBLEMS ARE EXPECTED PRIOR WEDNESDAY. ABOVE NORMAL
TEMPERATURES TUESDAY AND ESPECIALLY ON WEDNESDAY…WILL LIKELY LEAD
TO SNOW MELT BEGINNING. RUNOFF FROM SNOW MELT COMBINED WITH RAINFALL
AHEAD OF A COLD FRONT COULD CAUSE SOME RIVERS AND STREAMS TO RISE TO
NEAR BANKFULL.

AN APPROACHING WARM FRONT WILL BRING SNOW…SLEET…AND FREEZING
RAIN TO THE REGION TODAY INTO TONIGHT. TOTAL QPF LOOKS TO BE IN THE
TWO TENTHS TO ONE THIRD INCH RANGE…ALL FROZEN PRECIPITATION.

TUESDAY INTO WEDNESDAY…TEMPERATURES WILL START TO RUN ABOVE NORMAL
WITH SNOW MELT AN ISSUE…WHERE THE SNOW PACK STILL EXISTS. SNOW
MELT WILL BE SLOW THROUGH TUESDAY…BUT SHOULD ACCELERATE ON
WEDNESDAY AND MUCH WARMER TEMPERATURES AND STRONGER WINDS ARE
EXPECTED. THE SNOW LIQUID EQUIVALENT IN THE VALLEYS IS LESS THAN AN
INCH. THE WESTERN/SOUTHERN ADIRONDACKS…SOUTHERN GREENS…AND
BERKSHIRES…GENERALLY HAVE 2 TO 4 INCHES OF SNOW LIQUID EQUIVALENT.
LESS THAN 2 INCHES EXISTS IN THE EASTERN CATSKILLS. THIS VALUES ARE
BELOW NORMAL FOR LATE JANUARY.

THE AMOUNT OF QPF WITH THE COLD FRONT NOT CERTAIN AT THIS
TIME…WITH ANYWHERE FROM ONE HALF INCH TO POSSIBLY GREATER THAN ONE
INCH IN SOME AREAS POSSIBLE. THE COMBINATION OF SNOW MELT AND
RAINFALL WOULD RESULT IN SIGNIFICANT WITHIN BANK RISES IN MOST
AREAS. IT IS STILL TOO EARLY…AND UNCLEAR WITH LOW CONFIDENCE…IF
ANY FLOODING WILL OCCUR 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…
RECORD HIGHS FOR JANUARY 30TH…
ALBANY: 54 DEGREES 1974 (RECORDS DATE BACK TO 1874)
GLENS FALLS: 50 DEGREES 1974 (RECORDS DATE BACK TO 1949)
POUGHKEEPSIE: 60 DEGREES 2006 (RECORDS DATE BACK TO 1949)
BENNINGTON: 60 DEGREES 2006 (RECORDS DATE BACK TO 1998)

&&

.ALY WATCHES/WARNINGS/ADVISORIES…
CT…WINTER WEATHER ADVISORY UNTIL 7 AM EST TUESDAY FOR CTZ001-013.
NY…WINTER WEATHER ADVISORY UNTIL 7 AM EST TUESDAY FOR NYZ032-033-
038>043-047>054-058>061-063>066-082>084.
MA…WINTER WEATHER ADVISORY UNTIL 7 AM EST TUESDAY FOR MAZ001-025.
VT…WINTER WEATHER ADVISORY UNTIL 7 AM EST TUESDAY FOR VTZ013>015.

&&

$$
SYNOPSIS…NAS/JPV
NEAR TERM…NAS/JPV
SHORT TERM…JPV
LONG TERM…IAA
AVIATION…IAA
HYDROLOGY…JPV
CLIMATE…IAA

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