February 23, 2012 Forecast Discussion

000
FXUS61 KALY 231150
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
650 AM EST THU FEB 23 2012

.SYNOPSIS…
A WEAK AREA OF LOW PRESSURE WILL EXIT THE REGION THIS MORNING.
ANOTHER…STRONGER LOW PRESSURE SYSTEM…WILL AFFECT THE REGION LATE
THURSDAY NIGHT INTO FRIDAY NIGHT WITH ADDITIONAL RAIN AND HIGH
TERRAIN SNOW. SOME LINGERING SNOW SHOWERS ALONG WITH WINDY
CONDITIONS WILL OCCUR IN THE WAKE OF THE STORM ON SATURDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
- Changed Discussion —
AS 630 AM…BACK EDGE OF AN AREA OF SCATTERED TO NUMEROUS SHOWERS
(RAIN/SNOW) WAS OVER THE WESTERN PART OF THE FORECAST AREA AND
MOVING RAPIDLY EAST. EXPECT ANY PCPN ASSOCIATED WITH THIS LOW
PRESSURE/SURFACE BOUNDARY TO END BY MID OR LATE MORNING IN ALL
AREAS. LITTLE ADDITIONAL ACCUMULATION OF SNOW IS EXPECTED (HALF INCH
OR LESS) IN AREAS THAT GET SNOW SHOWERS. CLOUDY SKIES THIS MORNING
WILL BECOME PARTLY SUNNY BY THIS AFTERNOON…AND POSSIBLY MOSTLY
SUNNY ACROSS SOUTHERN AREAS. HIGHS TODAY ARE FORECAST TO RANGE FROM
THE MID 30S OVER THE ADIRONDACKS…TO THE LOWER OR MID 50S OVER THE
VALLEY LOCATIONS SOUTH OF ALBANY. COULD GO EVEN HIGHER IF ENOUGH
SUNSHINE OCCURS.
- End Changed Discussion -

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/…
MODEL TIMING DIFFERENCES CONTINUE TO EXIST CONCERNING THE NEXT LOW
PRESSURE SYSTEM. FOR NOW HAVE HELD OFF THE ARRIVAL OF PCPN UNTIL
AFTER MIDNIGHT TONIGHT…WITH MAINLY CATEGORICAL POPS LATE TONIGHT
THROUGH EARLY FRIDAY AFTERNOON…THEN POPS DECREASING DURING THE
AFTERNOON AS A DRY SLOT SURGES INTO THE REGION.

COLD ENOUGH FOR MAINLY SNOW OR SLEET THROUGH EARLY FRIDAY
MORNING…THEN A TRANSITION TO MAINLY RAIN IN ALL AREAS BY EARLY
FRIDAY AFTERNOON.

AS THE STORM MOVES BY LATE FRIDAY AFTERNOON AND FRIDAY EVENING…
COLDER AIR WILL BEGIN TO RETURN AT THE MID LEVELS AND PCPN WILL
TRANSITION BACK TO SNOW FRIDAY EVENING. BY THAT TIME STEADY PCPN
WILL HAVE ENDED WITH THE PCPN BECOMING SHOWERY IN NATURE AS A MOIST
NORTHWESTERLY FLOW PREVAILS FRIDAY NIGHT INTO SATURDAY.

HAVE FORECAST ADVISORY LEVEL SNOW FOR PARTS OF THE REGION FROM THE
EASTERN CATSKILLS TO THE ADIRONDACKS AND EASTWARD TO SOUTHERN
VERMONT. WITH THE PCPN NOT STARTING UNTIL LATE IN THE SECOND PERIOD
PREFFERED TO HOLD OFF ON ACTUALLY ISSUEING ANY ADVISORIES AT THIS
TIME.

LOWS THURSDAY NIGHT WILL BE IN THE MID 20S TO MID 30S. HIGHS FRIDAY
IN THE MID 30S TO UPPER 40S…LOWS FRIDAY NIGHT GENERALLY BETWEEN 20
AND 30…AND HIGHS SATURDAY IN THE UPPER 20S TO LOWER 40S.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/…
A PERIOD OF TRANQUIL WEATHER OPENS THE LONG TERM…AS AN UPPER
LEVEL TROUGH REMAINS OVER THE NORTHEAST…AND A BROAD CANADIAN
HIGH BUILDS IN FROM SOUTHERN ONTARIO TO CLOSE THE WEEKEND. A
SECONDARY COLD FRONT SLIPS THROUGH THE FCST AREA SATURDAY NIGHT
WITH ISOLD-SCT SNOW SHOWERS ENDING WEST OF THE HUDSON RIVER VALLEY
BEFORE MIDNIGHT…AS THE LOW AND MID LEVEL FLOW BECOMES
ANTICYCLONIC…AND THE SUBSIDENCE INVERSION LOWERS. H850 TEMPS
FALL INTO THE -10C TO -15C RANGE OVER THE FORECAST AREA WITH LOWS
IN SINGLE DIGITS OVER THE SRN DACKS…AND NRN LAKE GEORGE REGION.
TEENS WILL BE COMMON ELSEWHERE…EXCEPT IN THE CAPITAL
DISTRICT…MID HUDSON VALLEY…SRN TACONICS AND SRN LITCHFIELD
COUNTY WHERE SOME LOWER TO M20S WILL BE POSSIBLE. THE WINDS WILL
BE GRADUALLY SUBSIDING OVERNIGHT…AS THE LOW-LEVEL PRESSURE
GRADIENT WEAKENS.

SUNDAY-SUNDAY NIGHT…SFC HIGH PRESSURE CRESTS OVER NY AND NEW
ENGLAND TO CLOSE THE WEEKEND WITH SUNNY AND COLD CONDITIONS.
TEMPERATURES WILL BE NEAR NORMAL FOR LATE FEB. THE SFC HIGH
RETREATS EASTWARD OVER NRN NEW ENGLAND…AND THE CANADIAN MARITIMES.
THE WEAK MID LEVEL RIDGING FLATTENS…AS A CLIPPER LOW APPROACHES
FROM THE UPPER MIDWEST AND THE WRN GREAT LAKES REGION.

MONDAY-MONDAY NIGHT…THE BEST LOW-LEVEL BAROCLINIC ZONE WITH THE
CLIPPER STAYS WELL NORTH OF THE FCST AREA OVER SRN QUEBEC…AND
EXTREME NRN NY DURING THE DAY. A SLIGHT CHC OF RAIN OR SNOW SHOWERS
WAS KEPT OVER MOST OF THE FCST AREA MON PM. TEMPS WILL BE ABOUT 5
DEGREES ABOVE NORMAL. THE COLD FRONT TO THE SYSTEM SWINGS THROUGH
MON NIGHT INTO TUESDAY MORNING WITH SOME SCT SNOW SHOWERS. THE
MOISTURE CONVERGENCE ISN/T VERY IMPRESSIVE WITH THIS BOUNDARY BASED
ON THE LATEST GFS/ECMWF/CANADIAN GGEM.

TUESDAY…ANOTHER SECONDARY COLD FRONT MOVES THROUGH THE REGION
DURING THE DAY WITH A SURGE OF SEASONABLY COLD AIR. WE KEPT MOST OF
THE DAY DRY WITH HIGH PRESSURE RIDGING IN FROM THE NORTH AGAIN.
HIGH WILL GENERALLY BE IN THE MID AND U30S OVER THE MTNS…WITH
LOWER TO MID 40S COMMON IN THE VALLEYS.

TUESDAY NIGHT INTO WEDNESDAY…HIGH PRESSURE CRESTS OVER THE REGION
TUESDAY EVENING…AS A VIGOROUS LONGWAVE TROUGH IS CARVED OUT OVER
THE CNTRL PLAINS/UPPER MS RIVER VALLEY. THE GFS IS QUICK BRINGING
THE LOW PRESSURE SYSTEM INTO THE CNTRL GREAT LAKES REGION WITH
ISENTROPIC LIFT AHEAD OF THE WARM FRONT MOVING INTO THE REGION BY
DAYBREAK WEDNESDAY. THE ECMWF IS SLOWER WITH THE DEVELOPMENT OF THE
UPPER TROUGH BY 12-18 HOURS. WE LEANED CLOSER TO HPC HERE WITH THE
WARM ADVECTION PCPN AHEAD OF THE WARM FRONT GRADUALLY MOVING IN FROM
SOUTHWEST TO NORTHEAST DURING IN THE DAY. WE HAVE SLIGHT AND LOW
CHC POPS WED…AND CHC POPS THROUGH WED NIGHT. PREDOMINANT PTYPE
WILL BE SNOW AT THIS POINT WITH THE ONSET. THIS SYSTEM MAY UTILIZE
AN ABUNDANCE OF GULF MOISTURE…SO IT BEARS WATCHING LATE IN THE
WEEK. THERE ARE ALSO INDICATIONS OF A SECONDARY LOW FORMING
SOMETIME ON THU WITH THE PRIMARY WEAKENING OVER THE ERN GREAT LAKES
REGION. HIGHS ON WEDNESDAY WILL GENERALLY BE IN THE U20S TO M30S
OVER THE MTNS…AND M30S TO NEAR 40F IN THE VALLEYS.

&&

.AVIATION /09Z THURSDAY THROUGH MONDAY/…
LOW PRESSURE IS APPROACHING FROM WEST-CENTRAL PA THIS MORNING WITH
SOME SCATTERED RAIN AND SNOW SHOWERS MOVING INTO ERN NY. VFR
CONDITIONS WILL MIX WITH SOME MVFR CIGS/VSBYS WITH THE SHOWERS PRIOR
TO 12Z AT KPOU/KGFL/KALB. SOME IFR/LIFR FZFG BRIEFLY OCCURRED
BEFORE 06Z AT KGFL WITH CALM WINDS AND SOME CLEAR SKIES. THE VSBYS
JUMPED BACK UP RIGHT BEFORE THE 06Z TAF ISSUANCE. THE LOWER LEVELS
REMAIN DRY SO ANY SHOWER ACTIVITY WILL LIKELY YIELD VSBYS OF 3-5
SM. THE WINDS WILL BE LIGHT AND VARIABLE PRIOR TO SUNRISE…EXCEPT
AT KALB WHERE SOUTH WINDS WILL CONTINUE AT 5-10 KTS.

IN THE WAKE OF THE LOW PRESSURE SYSTEM AND ITS COLD FRONTAL PASSAGE
BETWEEN 12Z-15Z COLD ADVECTION OCCURS AND THE SFC WINDS INCREASE TO
10-16 KTS WITH SOME GUSTS AROUND 25 KTS…ESPECIALLY AT KALB IN THE
AFTERNOON. THE STRATOCUMULUS WILL BECOME SCATTERED…AND THE SKIES
WILL CLEAR…AS WEAK HIGH PRESSURE BUILDING OVER NY.

SOME CIRRUS WILL QUICKLY INCREASE AHEAD OF A WARM FRONT ASSOCIATED
WITH LOW PRESSURE ENTERING THE OHIO VALLEY AFTER 00Z/FRI. THERMAL
ADVECTION PCPN WILL MOVE BACK INTO THE REGION AFTER MIDNIGHT.

OUTLOOK….
THU NIGHT…MVFR/IFR WITH SN/IP/RA.
FRI…MVFR CIGS/VSBYS…TRANSITION TO RA. BECOMING WINDY.
FRI NGT…VFR/MVFR…CHC -SHSNS.
SAT…VFR…SLIGHT CHC -SHSN. WINDY.
SAT NIGHT-SUN…VFR…DECREASING WINDS.
MON…VFR SLIGHT CHC -SHRA/-SHSN.

&&

.HYDROLOGY…
HYDRO PROBLEMS APPEAR MINIMAL THE NEXT FIVE DAYS. LOW PRESSURE
EXITING THE REGION THIS MORNING WITH LIGHT PRECIPITATION AMOUNTS.
ANOTHER STRONGER SYSTEM LATE THURSDAY NIGHT INTO FRIDAY HAS THE
POTENTIAL TO BRING MODERATE PRECIPITATION AMOUNTS TO THE REGION WITH
AMOUNTS RANGING FROM LESS THAN HALF AN INCH…TO POSSIBLY AN INCH…
WHICH WOULD CAUSE MINOR RISES ON RIVERS AND STREAMS.

THE PROBABILITIES FOR FLOODING IS GENERALLY BELOW NORMAL DUE TO
BELOW NORMAL SNOWPACK AND LACK OF RIVER ICE. PLEASE REFER TO OUR
WINTER/SPRING FLOOD POTENTIAL OUTLOOK (ALBESFALY) ISSUED ON
FEBRUARY 16TH FOR DETAILS. NEXT ISSUANCE OF THIS PRODUCT IS
SCHEDULED FOR MARCH 1ST 2012.

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…GJM
NEAR TERM…GJM
SHORT TERM…GJM
LONG TERM…WASULA
AVIATION…WASULA
HYDROLOGY…GJM

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