February 12, 2013 Forecast Discussion

000
FXUS61 KALY 122031
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
331 PM EST TUE FEB 12 2013

.SYNOPSIS…
WEAK HIGH PRESSURE WILL BUILD INTO THE REGION TONIGHT INTO
WEDNESDAY…WITH GRADUAL AND PARTIAL CLEARING FOR MUCH OF THE AREA.
LOW PRESSURE WILL TRACK FROM THE SOUTHERN APPALACHIANS TO THE
VIRGINIA COAST BY WEDNESDAY EVENING…EVENTUALLY PASSING WELL SOUTH
OF LONG ISLAND WEDNESDAY NIGHT. THIS SYSTEM WILL ONLY GRAZE THE
EXTREME SOUTHERN PORTION OF THE AREA WITH SOME LIGHT SNOW. WEAK HIGH
PRESSURE WILL BUILD BACK IN FOR THURSDAY WITH DRY CONDITIONS AND
MILD TEMPERATURES.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/…
AS OF 330 PM EST…CLOUDS SKIES ENCOMPASSING PRETTY MUCH THE ENTIRE
AREA LATE THIS AFTERNOON WITH MOISTURE TRAPPED BENEATH A LOW LEVEL
INVERSION. EVEN THOUGH DRIER AIR WILL GRADUALLY WORK INTO THE
REGION TONIGHT…CLOUDS WILL BE STUBBORN TO ERODE AS IT WILL BE
DIFFICULT TO SCOUR OUT THE INVERSION. THERE IS A BETTER CHANCE OF
CLEARING LATE TONIGHT TOWARDS WEDNESDAY MORNING. HAVE MENTION OF
MOSTLY CLOUDY SKIES THROUGH MUCH OF THE NIGHT…WITH CLEARING
FIRST FORECAST TO OCCUR ACROSS SOUTHEAST PORTIONS OF THE AREA. AS
A RESULT OF MORE EXTENSIVE CLOUD COVER AND A LINGERING
BREEZE…WENT A FEW DEGREES ABOVE GUIDANCE FOR MIN TEMPERATURES
TONIGHT.

AS FOR ANY PRECIP CHANCES…THERE IS A WEAK/BORDERLINE LAKE RESPONSE
IN THE WESTERLY FLOW REGIME…BUT TEMPERATURES ALOFT ARE JUST NOT
COLD ENOUGH TO INVOKE ANY REAL DEVELOPMENT OF LAKE EFFECT SNOW
BANDS. LOW INVERSION HEIGHTS AROUND 1.5 KM WILL ALSO LIMIT ANY
ORGANIZATION. AS A RESULT…JUST SOME MAINLY SCATTERED LIGHT LAKE
ENHANCED SNOW SHOWERS ARE EXPECTED FOR THE WESTERN ADIRONDACKS AND
MOHAWK VALLEY. ONLY EXPECTING A DUSTING TO A HALF INCH IN THESE
LOCATIONS THROUGH TONIGHT. THE ONLY OTHER LOCATION WHERE POPS ARE
INCLUDED FOR TONIGHT IS A LIMITED AREA OF THE SPINE OF THE SOUTHERN
GREEN MOUNTAINS IN VERMONT WHERE ISOLATED UPSLOPE SNOW SHOWERS WILL
BE POSSIBLE…AGAIN WITH VERY LIGHT SNOWFALL AMOUNTS.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/…
ANY LINGERING LAKE ENHANCED SNOW SHOWERS SHOULD END WEDNESDAY
MORNING AS WEAK HIGH PRESSURE BUILDS IN AND DRIER LOW LEVEL AIR
WORKS IN. TEMPERATURES ARE EXPECTED BE SLIGHTLY ABOVE NORMAL FOR
DAYTIME HIGHS.

CLOUDS WILL BE INCREASING BY LATE WEDNESDAY…AS A SOUTHERN STREAM
LOW PRESSURE SYSTEM MOVES TO THE TIDEWATER VIRGINIA AREA. NO PHASING
OF NORTHERN STREAM ENERGY IS EXPECTED WITH THIS SYSTEM…SO IT
SHOULD CONTINUE ITS NORTHEASTWARD TRACK AND PASS WELL SOUTH OF LONG
ISLAND. SOME WEAK ISENTROPIC LIFT ON THE NORTHERN EDGE WILL BRING
ABOUT A 50-60 PERCENT CHANCE OF LIGHT SNOW TO EXTREME SOUTHERN AREAS
WEDNESDAY EVENING INTO WEDNESDAY NIGHT. ANY ACCUMULATIONS ARE
EXPECTED TO LESS THAN AN INCH FOR THIS LIMITED AREA OF SOUTHERN
ULSTER…DUTCHESS AND LITCHFIELD COUNTIES. THERE IS GOOD MODEL
AGREEMENT REGARDING THIS SYSTEM AND THUS HIGH CONFIDENCE IN ITS
TRACK AND IMPACT ON OUR FORECAST AREA.

THURSDAY SHOULD FEATURE DRY CONDITIONS AND AT LEAST PARTLY SUNNY
SKIES WITH WEAK HIGH PRESSURE BUILDING IN FROM THE OHIO VALLEY.
TEMPERATURES SHOULD RESPOND NICELY WITH MAX READINGS RUNNING AT
LEAST 5 DEGREES ABOVE NORMAL OVER MUCH OF THE AREA.

SOMEWHAT MORE UNSETTLED WEATHER EXPECTED FOR THURSDAY NIGHT INTO
FRIDAY…AS SLOW MOVING LOW PRESSURE TRACKS ACROSS SOUTHERN ONTARIO
AND QUEBEC WHICH WILL DRAG MULTIPLE FRONTAL BOUNDARY THROUGH THE
AREA. THE BEST CHANCE FOR MEASURABLE PRECIP WILL BE OVER FAVORED
UPSLOPE AREAS MAINLY NORTH AND WEST OF THE CAPITAL REGION…ALTHOUGH
MOST OF THE REGION SHOULD SEE A CHANCE OF A FEW RAIN/SNOW SHOWERS
ASSOCIATED WITH A COLD FRONT PASSAGE TOWARDS LATE FRIDAY. AHEAD OF
THE COLD FRONT TEMPERATURES ARE EXPECTED TO BE MILD…ESPECIALLY
FROM THE HUDSON RIVER VALLEY EASTWARD.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/…
THE LONG TERM PERIOD WILL BEGIN WITH AN AMPLIFYING LONG WAVE TROUGH
DIGGING INTO THE EASTERN CONUS. THIS DIGGING LOOKS TO RESULT IN A
SIGNIFICANT CYCLONE. THE CANADIAN MODEL DEVELOPS THIS STORM ALONG
THE COAST…TRACKING NORTHWARD. THEREFOR ITS SOLUTION WOULD PRODUCE
A HIGH IMPACT SNOWSTORM OR MIXED PRECIPITATION EVENT LATE SATURDAY
INTO SUNDAY.

THE OTHER TWO GLOBAL MODELS…THE 12Z OPERATIONAL GFS AND 12Z
OPERATIONAL ECMWF CONTINUE TO DEVELOP A STORM WELL TO THE EAST OF
THE COAST AND WOULD BE A PROBLEM ONLY TO SHIPPING LANES.

MORE THAN HALF OF THE GFS ENSEMBLE MEMBERS SUPPORT LITTLE OR NO
SNOW. THERE ARE STILL ABOUT A THIRD OF THE MEMBERS THAT COULD
SUPPORT HEAVIER TO MUCH HEAVIER QPF AMOUNTS (OVER AN INCH) WITH ONE
MEMBER EVEN IMPLYING RAIN.

OUT AHEAD OF THE DEVELOPING STORM…A POTENT COLD FRONT COULD BRING
SOME SNOW SHOWERS TO THE REGION…MAINLY NORTH AND WEST OF THE
CAPITAL DISTRICT. FOR THIS REASON WILL KEEP 20 POPS IN MOST PLACES
(30-40 POPS HIGHER TERRAIN WEST OF ALBANY) FOR FRIDAY NIGHT THROUGH
SATURDAY NIGHT.

BY SUNDAY…AS THE OCEAN STORM CRANKS UP…IT WILL PULL A PRETTY
COLD SHOT OF AIR OUR WAY DOWN FROM EASTERN CANADA. H850 TEMPS LOOK
TO DIP TO ABOUT -15C TO -20C ACROSS OUR AREA (EVEN A LITTLE COLDER
OFF THE 12Z GFS). EITHER WAY YOU SLICE IT…IT WILL BE BLUSTERY
SUNDAY INTO SUNDAY WITH SCATTERED SHOWERS MAINLY NORTH AND WEST OF
ALBANY.

MONDAY…AS HIGH PRESSURE BUILDS TO OUR SOUTHEAST…THE SOUTHWEST
FLOW AND INCREASING FEBRUARY SUNSHINE…SHOULD ALLOW FOR A PARTIAL
RECOVERY BACK TO NEARLY NORMAL MID FEBRUARY LEVELS.

THE NEXT NORTHERN STREAM SYSTEM LOOKS TO WASTE NO MORE MOVING TOWARD
US FROM THE OHIO VALLEY COME TUESDAY INTO TUESDAY NIGHT. WITH A
CONTINUED SOUTHERLY FETCH AHEAD OF THE STORM…TEMPERATURES MIGHT
WARM ENOUGH FOR SOME RAIN.

HOWEVER…THERE ARE DIFFERENCE BY THE END OF THE FORECASTING PERIOD.
THE GFS DEVELOPS A DEEP STORM THE MOVES ACROSS THE SAINT LAWRENCE
VALLEY INTO CANADA. SUCH A TRACK WOULD BRING MOSTLY RAIN TO OUR
REGION INTO EARLY WEDNESDAY…FOLLOWED BY A QUICK COOL DOWN AND
PERHAPS SOME WIND ISSUES.

THE ECMWF ON THE OTHER HAND…DEVELOPS A STORM JUST TO OUR EAST ON
WEDNESDAY…WHICH COULD EASILY PULL ENOUGH COLD AIR TO CHANGE ANY
RAIN BACK TO SNOW. THERE COULD BE QUITE A BIT OF IT.

IT IS WAY TO EARLIER TO ACCESS WHICH SOLUTION WILL BE CORRECT THIS
FAR OUT. FOR NOW…WENT WITH A BLEND OF THE TWO SOLUTIONS WITH 30
POPS OF RAIN OR SNOW SHOWERS.

OVERNIGHT LOWS IN FRIDAY WILL BE IN THE 20S FROM ALBANY
SOUTHWARD…TEENS NORTH. HIGHS WILL BE IN THE 30S SATURDAY…EXCEPT
UPPER 20S IN THE ADIRONDACKS. TEMPERATURES LOOK TO TUMBLE TO THE
TEENS SATURDAY NIGHT…EXCEPT SINGLE NUMBERS ACROSS THE ADIRONDACKS.
SUNDAY…HIGHS WILL BE MAINLY IN THE 20S (TEENS NORTH). THE WIND
SHOULD MAKE IT FEEL AT LEAST 10 DEGREES COLDER. TEMPERATURES WILL
DIP TO BETWEEN AROUND 0 TO 15 SATURDAY NIGHT.

BY MONDAY…LOOK FOR HIGHS TO RECOVER TO THE LOWER TO MID 30S MOST
PLACES EXCEPT SOUTHERN VERMONT AND THE ADIRONDACKS WHEE THEY WILL
REACH THE UPPER 20S. LOWS WILL BE BACK DOWN GENERALLY IN THE TEENS
MONDAY NIGHT. TUESDAY LOOKS MILDER YET WITH HIGHS 35 TO 40 IN THE
VALLEYS…UPPER 20S TO MID 30S HIGHER TERRAIN.

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/…
MVFR CIGS WILL PREVAIL AT KPSF THROUGH THIS EARLY EVENING…AND
OCCASIONALLY AT KALB THROUGH THIS AFTERNOON. WE ARE QUITE
CONFIDENT CIGS WILL NOT DROP TO IFR AND PROBABLY NOT EVEN LOW
MVFR. (CIGS SHOULD REMAIN 2000 FEET OR HIGHER).

OTHERWISE VFR CONDITIONS WILL PREVAIL THROUGH TONIGHT AT THE
REMAINDER OF THE TAF SITES INCLUDING KALB/KPSF.

WE ARE NOT CONFIDENT THE CIGS WILL ERODE UNTIL LATER OVERNIGHT BUT
WE BELIEVE CIG BASES WILL BE SAFELY IN THE VFR RANGE LATER THIS
EVENING.

A GUSTY BREEZE WILL ENSUE AT ALL OF THE TAFS (STRONGEST AT
KPSF/LESS AT KGFL). LOOK FOR A MAINLY WEST WIND 10-15KTS THIS
KNOTS GUSTING 20KTS OR HIGHER (AROUND 30KTS AT KPSF AND KALB).

THESE WINDS DIMINISH DURING THE EVENING…BECOMING LIGHT AND
VARIABLE OVERNIGHT.

VFR CONDITIONS SHOULD HOLD THROUGHOUT THE DAY WEDNESDAY ALTHOUGH
CLOUDS WILL THICKEN TO THE SOUTH WHERE SOME SNOW MIGHT ARRIVE
AFTER DARK.

OUTLOOK…
WED…VFR. NO SIG WX.
WED NIGHT…VARIABLE CONDITIONS. KPOU…SUB-VFR WITH LIGHT SNOW
LIKELY. KPSF…SUB-VFR POSSIBLE WITH A CHC LIGHT SNOW.
KALB…MAINLY VFR WITH A SLIGHT CHC LIGHT SNOW. KGFL…VFR NO SIG
WX.
THU…VFR. NO SIG WX.
THU NIGHT…MAINLY VFR. CHC OR SCHC -SHSN.
FRI…MAINLY VFR. SLIGHT CHC -SHSN/-SHRA.
SAT…MAINLY VFR. SLIGHT CHC -SHSN.

&&

.HYDROLOGY…
WEAK HIGH PRESSURE OVER THE REGION WILL BRING MAINLY DRY WEATHER
TONIGHT INTO WEDNESDAY…EXCEPT FOR SOME LIGHT SNOW SHOWERS OVER THE
WESTERN ADIRONDACKS AND MOHAWK VALLEY. A LOW PRESSURE SYSTEM WILL
PASS WELL SOUTH OF LONG ISLAND WEDNESDAY NIGHT BRINGING JUST SOME
VERY LIGHT SNOW ACCUMULATIONS TO THE EXTREME SOUTHERN PORTION OF THE
AREA.

HIGH PRESSURE WILL BUILD BACK IN FOR THURSDAY…BEFORE A RELATIVELY
WEAK SYSTEM MOVES IN THURSDAY NIGHT INTO FRIDAY WITH LIGHT
PRECIPITATION. ANY OF THESE SYSTEMS THROUGH THE REST OF THE WORK
WEEK ARE NOT EXPECTED TO HAVE ANY IMPACT ON AREA RIVERS AND STREAMS.

AT THIS TIME IT APPEARS A POTENTIAL STORM SYSTEM WILL TRACK WELL TO
OUR SOUTH FOR THE WEEKEND…ALTHOUGH THE PROBABILITY THAT THE STORM
WILL IMPACT OUR REGION IS NOT ZERO.

SNOW MELT DURING THE PERIOD WILL BE GRADUAL…AS ABOVE FREEZING
TEMPERATURES DURING THE DAY WILL COOL TO BELOW FREEZING EACH NIGHT.

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…NONE.
NY…NONE.
MA…NONE.
VT…NONE.

&&

$$
SYNOPSIS…JPV
NEAR TERM…JPV
SHORT TERM…JPV
LONG TERM…HWJIV
AVIATION…HWJIV
HYDROLOGY…JPV

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