February 27, 2013 Forecast Discussion

000
FXUS61 KALY 272120
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
420 PM EST WED FEB 27 2013

.SYNOPSIS…
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LOW PRESSURE WILL MOVE OVER UPSTATE NEW YORK WITH THE MIXTURE OF
RAIN AND SNOW TRANSITIONING BACK TO SNOW TONIGHT. THE UPPER LEVEL
LOW WILL REMAIN OVER NEW YORK AND NEW ENGLAND TOMORROW INTO FRIDAY
WITH CHANCES OF RAIN AND SNOW SHOWERS CONTINUING. BY THE
WEEKEND…HIGH PRESSURE WILL START TO BUILD IN WITH FAIR AND
SEASONABLE WEATHER.
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&&

.NEAR TERM /UNTIL 6 AM THURSDAY/…
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AS OF 400 PM EST…A COMPLEX STORM SYSTEM CONTINUES TO IMPACT THE
ALY FCST AREA. ONE LOW PRESSURE SYSTEM CONTINUES TO SPIN OVER
MICHIGAN WITH A SECONDARY LOW MOVING OVER THE NY/PA BORDER. THIS
DOUBLE BARREL LOW PRESSURE SYSTEM WILL CONTINUE TO PRODUCE RAIN
AND SNOW LATE THIS AFTERNOON INTO THIS EVENING. THE SECONDARY LOW
IS GETTING CAPTURED BY THE ELONGATED SECTION OF THE BROAD H500
CIRCULATION. COLDER AIR IS STARTING TO FILTER BACK IN FROM THE
W/SW ACROSS CNTRL-ERN NY.

ALSO…THE SIGNIFICANT DOWNSLOPING WITH THE E/SE WINDS OFF THE SRN
GREENS…BERKS…AND TACONICS…HAS DIMINISHED WITH THE RADAR
ECHOES STARTING TO FILL BACK IN OVER THE CAPITAL DISTRICT…NRN
TACONICS…AND THE UPPER HUDSON VALLEY. THE STRONG LLJ HAS MOVED
NORTH OF THE REGION. THE WIND ADVISORY HAS BEEN CANCELED FOR THE N-CNTRL
TACONICS…BERKS…AND SRN GREENS.

ALSO…THE BEST ACCUMULATING SNOWFALL LATE THIS AFTERNOON INTO
THIS EVENING WILL BE FOR THE SRN AND ERN DACKS…SRN VT…AND THE
NRN BERKSHIRES WITH SNOW LEVELS AROUND 2 KFT AGL CURRENTLY…AND
LOWERING TO VALLEY FLOOR LOCATIONS OVERNIGHT. THE WARNINGS WILL
REMAIN IN PLACE UNTIL 6 AM FOR THESE LOCATIONS FOR STORM TOTAL
AMOUNTS IN THE 6-12 INCH RANGE…AND ADDITIONAL SNOW AMOUNTS OF 2
TO 6 INCHES 6 PM TONIGHT TO 6 AM TOMORROW. THE ADVISORIES OVER THE
MOHAWK VALLEY…SRN BERKS…SCHOHARIE VALLEY…AND LOWER LAKE
GEORGE AND NRN SARATOGA REGION HAVE BEEN DROPPED WITH ADDITIONAL
SNOW ACCUMS OF 1 TO 2 INCHES. THE WARNINGS HAVE ALSO BEEN CANCELED
FOR THE HELDERBERGS AND THE ERN CATSKILLS WITH ONLY LIGHT
ACCUMULATIONS OF 1 TO 3 INCHES EXPECTED. LOCATIONS FROM THE
CAPITAL REGION SOUTH AND EAST WILL GET A COATING TO MAYBE AN INCH.

WEAK COLD ADVECTION WILL OCCUR IN THE WAKE OF THE SFC LOW MOVING
OVER WRN-CNTRL NY. H850 TEMPS FALL TO -3C TO -5C OVER THE REGION
WITH PLENTY OF CLOUDS AROUND. EXPECT LOWS IN THE U20S TO L30S IN
THE VALLEYS. MID AND U20S ARE LIKELY OVER THE HILLS AND MTNS.
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&&

.SHORT TERM /6 AM THURSDAY THROUGH SATURDAY/…
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THURSDAY…THE CYCLONE OCCLUDES AND BECOMES STACKED OVER LAKE
ONTARIO AND NRN NY. THE CYCLONIC VORTICITY ADVECTION ASSOCIATED
WITH THE STORM WILL CONTINUE CHANCES OF RAIN AND SNOW SHOWERS TIED
TO THE DIURNAL HEATING. THE HIGHER POPS WERE CONTINUED NORTH AND
WEST OF THE CAPITAL REGION…AND ALONG THE WRN SPINE OF THE GREEN
MTNS…BERKSHIRES…AND TACONICS. ENOUGH WARMING IN THE BOUNDARY
LAYER WILL ALLOW TEMPS TO REACH THE 40S IN THE VALLEY
LOCATIONS…AND MID30S TO NEAR 40F OVER THE HILLS AND MTNS. SOME
MID AND U40S MAY OCCUR SOUTH OF THE CAPITAL DISTRICT OVER THE MID
HUDSON VALLEY…AND SRN LITCHFIELD COUNTY.

THU NIGHT…THE STACKED LOW SLOWLY MOVES EASTWARD OVER ERN NY AND WRN NEW
ENGLAND THU NIGHT. COLDER AIR MOVES IN OVER THE REGION TURNING ANY
RAIN OR SNOW SHOWERS BACK TO SNOW SHOWERS. THE BEST CHANCE FOR
LIGHT SNOW ACCUMS WILL BE OVER THE HIGHER TERRAIN GREATER THAN
1000 FT. LOWS WILL GENERALLY BE IN THE 20S WITH SOME TEENS OVER
THE ADIRONDACK PARK.

FRI-FRI NIGHT…THE CLOSED UPPER LOW MOVES OVER NEW ENGLAND WITH
ISOLD-SCT RAIN AND SNOW SHOWERS NORTH AND WEST OF THE MID HUDSON
VALLEY. COLDER AIR FILTERS IN OVER THE FCST AREA WITH TEMPS A TAD
COLDER THAN THU. EXPECT HIGHS IN THE M30S TO L40S IN THE
VALLEYS…AND U20S TO M30S OVER THE MTNS.

SATURDAY…THE UPPER LOW FINALLY BEGINS TO LOSE ITS GRIP ON THE
FORECAST AREA WITH A SLIGHT TO LOW CHC OF RAIN OR SNOW SHOWERS
NORTH AND WEST OF THE CAPITAL REGION. THERE MAY BE A FEW BREAKS OF
SUN IN THE AFTERNOON WITH SEASONABLE TEMPS FOR EARLY MARCH.
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&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/…
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CHAOTIC UPPER PATTERN OVER EASTERN NORTH AMERICA WITH A MEAN UPPER
TROUGH AND UPPER CUTOFFS ROTATING THROUGH THE CYCLONIC FLOW AROUND
THE MEAN UPPER TROUGH.

LOW LEVEL FLOW LOOKS TO BE MOSTLY NORTHERLY…LIMITING ANY LAKE
EFFECT INFLUENCES. HOWEVER…MEAN NORTH TO NORTHWEST UPPER FLOW
ALONG WITH PERIODIC UPPER DYNAMICS ASSOCIATED WITH THE UPPER LOWS
AND UPPER IMPULSES COULD RESULT IN NORTHWEST FLOW ENHANCED SNOW
SHOWER ACTIVITY IN HIGHER TERRAIN OF THE SOUTHERN
ADIRONDACKS…NORTHERN TACONICS…SOUTHERN GREEN MOUNTAINS AND MAYBE
INTO THE NORTHERN BERKSHIRES…SCHOHARIE AREA AND EASTERN CATSKILLS.

SO…QUITE A BIT OF CLOUDINESS THROUGH THE PERIOD WITH ONLY
OCCASIONAL PERIODS OF BREAKS. THE BEST CHANCES AT BREAKS IN THE
CLOUDS ARE IN THE CAPITAL DISTRICT THROUGH THE MID HUDSON VALLEY AND
NORTHWEST CT…BUT EVEN THERE…MORE CLOUDS THAN BREAKS THROUGH THE
PERIOD…UNTIL THE MEAN UPPER TROUGH EXITS EAST AT THE END OF THE
PERIOD TOWARD THE BEGINNING AND MIDDLE OF NEXT WEEK.

THE UNCERTAINTIES ASSOCIATED WITH THE NORTHWEST FLOW SNOW SHOWER
ACTIVITY SUGGESTS INCLUDING SCATTERED SNOW SHOWER ACTIVITY IN THE
AFOREMENTIONED AREAS OF TERRAIN THROUGH AT LEAST SUNDAY…WITH MORE
ISOLATED ACTIVITY MONDAY THROUGH WEDNESDAY. BOUNDARY LAYER
TEMPERATURES SUGGEST HIGHS THROUGH THE PERIOD A LITTLE BELOW NORMAL
BUT NOT MUCH BELOW NORMAL WITH ALL THE CLOUD COVER. LOW
TEMPERATURES SHOULD NOT STRAY TOO FAR FROM NORMAL WITH THE CLOUD
COVER. HIGHS TREND TO AROUND NORMAL BY MONDAY THROUGH WEDNESDAY AS
THE MEAN UPPER TROUGH SHIFTS EASTWARD AND THE PROSPECTS FOR MORE SUN
THAN CLOUDS.
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&&

.AVIATION /21Z WEDNESDAY THROUGH MONDAY/…
A LARGE AREA OF LOW PRESSURE WILL CONTINUE TO AFFECT THE
AREA…MOVING ONLY SLOWLY EASTWARD WITH TIME. INTERMITTENT RAIN WILL
IMPACT THE KALB/KPOU/KPSF/KGFL TAF SITES THROUGH THIS AFTERNOON AND
INTO THIS EVENING. DUE TO AN EASTERLY FLOW ALOFT…DOWNSLOPING WILL
ALLOW FOR MAINLY VFR/MVFR CONDITIONS EXCEPT FOR BORDERLINE MVFR/IFR
AT KPSF WHICH IS LOCATED MORE IN THE HIGHER TERRAIN AND IS LESS
IMPACTED BY DOWNSLOPE EASTERLY FLOW. WILL MENTION A TEMPO GROUP FOR
A FEW HOURS AT KPSF STARTING AT 18Z. OTHERWISE…PRECIP MAY MIX WITH
OR CHANGE TO LIGHT SNOW LATER THIS EVENING INTO THE OVERNIGHT
HOURS…ESPECIALLY AT KGFL/KPSF. GENERALLY MVFR CONDITIONS ARE
EXPECTED OVERNIGHT…WITH A CHANCE FOR SOME PERIODS OF IFR.

WINDS WILL INITIALLY BE EASTERLY AROUND 10 KT WITH SOME OCCASIONAL
GUSTS NEAR 20 KT. WINDS WILL BECOME LIGHT AND VARIABLE THIS
EVENING…CONTINUING THROUGH THE OVERNIGHT AND INTO THURSDAY MORNING.

OUTLOOK…
THU-FRI…VFR/MVFR. CHC -SHSN/-SHRA.
SAT-SUN…VFR/MVFR. NO SIG WX.

&&

.HYDROLOGY…
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WIDESPREAD HYDRO PROBLEMS ARE NOT EXPECTED THE NEXT 5 DAYS.
ADDITIONAL SNOW AMOUNTS WILL RANGE FROM 2 TO 6 INCHES NORTH AND
EAST OF THE CAPITAL REGION. TOTAL ADDITIONAL LIQUID EQUIVALENTS
AMOUNTS WILL RANGE FROM 5 HUNDREDTHS TO A THIRD OF AN INCH TONIGHT.

THURSDAY INTO SATURDAY…THE UPPER LEVEL LOW WILL PRODUCE LIGHT
PRECIPITATION AMOUNTS FROM RAIN AND SNOW SHOWERS. SOME MELTING OF
THE SNOW PACK WILL OCCUR IN THE VALLEY LOCATIONS INTO THE WEEKEND
WITH LITTLE EFFECT ON THE MAIN STEM RIVERS AND WATERWAYS.

DRIER WEATHER IS EXPECTED ON THE WEEKEND WITH SEASONABLE TEMPS.

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.
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&&

.ALY WATCHES/WARNINGS/ADVISORIES…
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CT…NONE.
NY…WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR NYZ033-042-
082.
MA…WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR MAZ001.
VT…WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR VTZ013>015.
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&&

$$
SYNOPSIS…WASULA
NEAR TERM…WASULA
SHORT TERM…WASULA
LONG TERM…NAS
AVIATION…JPV
HYDROLOGY…HWJIV/WASULA

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