January 26, 2012 Forecast Discussion

000
FXUS61 KALY 261127
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
627 AM EST THU JAN 26 2012

.SYNOPSIS…
A POTENT STORM SYSTEM DEVELOPING ACROSS THE LOWER MISSISSIPPI
VALLEY WILL TRACK NORTHEAST TOWARD THE EASTERN GREAT LAKES TODAY
INTO FRIDAY. THIS SYSTEM WILL BRING MAINLY RAIN TO AREAS SOUTH OF
ALBANY TONIGHT AND EARLY FRIDAY…WITH A WINTRY MIX CHANGING TO
RAIN FOR HIGHER TERRAIN AND AREAS NORTH AND EAST OF ALBANY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
FLURRIES HAVE ENDED AND CLOUD COVER IS BREAKING UP IN SOME AREAS.
SO…THERE WILL BE A PERIOD OF CLOUDS AND SUN BEFORE THE OVERCAST
RETURNS AHEAD OF THE SYSTEM WE ARE EXPECTING TONIGHT. SO…A FEW
ADJUSTMENTS TO TEMPERATURES…CLOUD COVER AND REMOVED THE
FLURRIES FOR THIS MORNING.

PREV AFD BELOW…

WINTER WEATHER ADVISORY IN EFFECT FOR LATE THIS AFTERNOON THROUGH
TONIGHT…AND IN NORTHERN AREAS THROUGH TOMORROW MORNING.
OCCASIONAL FLURRIES SHOULD DIMINISH BY SUNRISE…BUT ACKNOWLEDGING
SOME FLURRIES FOR A FEW HOURS THIS MORNING. BASED ON SATELLITE
IMAGERY…MOSTLY CLOUDY TO CLOUDY SHOULD PREVAIL THROUGH THE
DAY…AS THE NEXT SYSTEM APPROACHES. WINDS SHOULD BE LIGHT…SO
HIGH TEMPERATURES SHOULD BE ON THE COOLER SIDE OF THE GUIDANCE.
STILL…MOST AREAS SHOULD GET ABOVE FREEZING…ALTHOUGH NORTHERN
AREAS AND HIGHER TERRAIN MAY BARELY GET ABOVE FREEZING.
PRECIPITATION IS EXPECTED TO ARRIVE IN THE EASTERN CATSKILLS AND
THE MID HUDSON VALLEY LATER THIS AFTERNOON…THEN SPREAD ACROSS
MOST AREAS BY EVENING. PRECIPITATION SHOULD BEGIN AS A MIX SINCE
TEMPERATURES THROUGH A DEEP LAYER SHOULD BE BELOW FREEZING DURING
THE ONSET…EXCEPT FOR SURFACE TEMPERATURES. ONCE PRECIPITATION
BEGINS…TEMPERATURES SHOULD BEGIN TO FALL TOWARD WET BULBS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/…
SOME OF THE MIXED PRECIPITATION AND TEMPERATURES ARE NOT RESOLVED
WELL IN THE TEXT FORMATTERS. SO…SOME AREAS UNDER AN ADVISORY
HAVE SOME TEXT INDICATING PLAIN RAIN…BUT POINT AND CLICK IN
VARIOUS SPOTS WITHIN THE AREA WILL SHOW WHERE THE FREEZING RAIN
IS EXPECTED. ALSO…AREAS AND TIMING OF THE ADVISORY MAY BE
ADJUSTED LATER TODAY DEPENDING ON TRENDS IN DATA AND NEW GUIDANCE.

HUDSON VALLEY AREAS FROM THE CAPITAL DISTRICT SOUTH AND
INCLUDING THE TACONICS AND NW CT SHOULD STAY JUST ABOVE FREEZING
THROUGH THE EVENT. SO…NO WINTER WEATHER ADVISORIES IN THOSE
AREAS. TEMPERATURES WILL WARM ALOFT AND LOW LEVEL TEMPERATURES
WILL COOL TO WET BULBS UNTIL AROUND MIDNIGHT. AS AGEOSTROPHIC
WINDS ABOVE THE SURFACE COME FROM THE NORTH AND EAST IT WILL
ANCHOR COLDER AIR IN THE AREAS UNDER THE WINTER WEATHER ADVISORY.
TEMPERATURES AT AND ABOVE THE BOUNDARY LAYER WILL WARM…CAUSING
PRECIPITATION TO CHANGE TO FREEZING RAIN IN THE ADVISORY AREA.
SURFACE TEMPERATURES SHOULD BEGIN TO RISE BY SUNRISE IN MOST
AREAS…AND PRECIPITATION WILL TRANSITION TO JUST A COLD RAIN FROM
SOUTH TO NORTH THROUGH FRIDAY MORNING. ANY SNOW ACCUMULATIONS
SHOULD BE AN INCH OR LESS AND ICE ACCUMULATIONS OF A THIRD OF AN
INCH OR LESS.

SYSTEM SHOULD EXIT FRIDAY AFTERNOON WITH PRECIPITATION BECOMING
SHOWERY AND WEST TO NORTHWEST WINDS BECOMING BREEZY. THE WINDS AND
ASSOCIATED MIXING TOWARD DRY ADIABATIC LAPSE RATES SHOULD ALLOW
MANY AREAS TO REACH INTO THE 40S…SOME AROUND 50 SOUTHERN
AREAS…AND UPPER 30S NORTHERN AREAS. WINDS WILL GRADUALLY
DIMINISH FRIDAY NIGHT…BUT SOME WIND AND VERY GRADUAL CLEARING
SHOULD RESULT IN LOW TEMPERATURES IN THE HIGHER END OF GUIDANCE.
STILL…LOWS FRIDAY NIGHT IN THE 20S…WITH TEENS IN THE SOUTHERN
ADIRONDACKS.

ON SATURDAY…ANOTHER QUICK MOVING NORTHERN STREAM SYSTEM TRACKS
THROUGH THE REGION…THIS ONE WEAKER AND WITH LESS MOISTURE.
SO…WITH SOME PERIODS OF CLOUDS AND SOME SMALL CHANCES OF RAIN
AND SNOW SHOWERS…HIGHS IN THE 30S TO LOWER 40S. CLEARING
SATURDAY NIGHT WITH LOWS IN THE 20S…SOME TEENS IN THE SOUTHERN
ADIRONDACKS.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/…
AS PREVIOUS DISCUSSION SUGGESTED…THIS LONG TERM PERIOD OF THE
FORECAST CONTINUES TO FEATURE CLIPPER-TYPE SYSTEMS TRACKING ALONG
THE U.S./CANADIAN BORDER.

THE FIRST OF THESE CLIPPERS IS EXPECTED OVER THE WEEKEND THAT IS
FORECAST TO TRACK ALONG THE SOUTHERN PERIPHERY OF THE HUDSON BAY
LOW. CHANCE POPS…WITH SLIGHTLY HIGHER VALUES DOWNWIND OF LAKE
ONTARIO…AND COOLER TEMPERATURES AS EXPECTATIONS OF THOSE 850MB
TEMPS DROP BACK TO -10C OR LOWER. THERE IS SOME TIMING ISSUES WITH
RESPECT TO THE COLD ADVECTION WITH THE ECMWF BEING THE SLOWEST. THE
CANADIAN SEEMS TO BE THE MIDDLE GROUND AND WILL FOLLOW ITS
COMPROMISED SOLUTION.

THIS CLIPPER SLIDES EAST BY MONDAY AS A LARGE ELONGATED NORTH-SOUTH
SURFACE HIGH TRACKS ACROSS THE EASTERN CONUS. OUTSIDE OF SOME
RESIDUAL FLURRIES DOWNWIND OF LAKE ONTARIO…IMPROVING CONDITIONS
WITH SEASONABLE TEMPERATURES FOR THE EARLY WEEK PERIOD.

THE NEXT CLIPPER APPROACHES THE NORTHERN PLAINS ON TUESDAY. SURFACE
WARM FRONT EVOLVES OVER THE CENTRAL GREAT LAKES REGION AND OHIO
RIVER VALLEY. THIS FEATURE TRACKS NORTHEAST WITH A PERIOD OF
OVERRUNNING PRECIPITATION EXPECTED TO DEVELOP TUESDAY-WEDNESDAY
TIMEFRAME. AT THIS TIME…THE BEST ISENTROPIC LIFT AND LOW LEVEL
JET DYNAMICS REMAINS OVER NY STATE WHICH PLACES THE HIGHER POPS WEST
OF THE HUDSON RIVER. PTYPE WILL VARY DUE TO DIURNAL RANGES AND THE
WARM ADVECTION PROCESS…FOR NOW…RAIN/SNOW MIXTURE.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/…
AREA OF LIGHT SNOW/FLURRIES IMPACTED KGFL-KALB WHERE MVFR AND IFR
THRESHOLDS WERE MET. IN THE WAKE OF THE LIGHT SNOW/FLURRIES…SOME
BR/MIFG WAS IN PLACE AS THIS SHOULD ABATE LATER THIS MORNING.
FLIGHT CONDITIONS SHOULD IMPROVE TOWARD HIGH END MVFR WHICH SHOULD
BE FOR THE BALANCE OF THE DAYLIGHT HOURS.

TOWARD SUNSET…CONDITIONS WILL RAPIDLY DETERIORATE TOWARD IFR WITH
A MIXTURE OF RAIN/FZRA/SLEET/SNOW MOVING INTO THE REGION. KPOU
SHOULD REMAIN RAIN…WITH KALB-KGFL EXPERIENCING THE WINTRY
PRECIPITATION.

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

&&

.HYDROLOGY…
A COMPLEX STORM SYSTEM WILL APPROACH THE REGION FROM THE SOUTHWEST
LATE THU INTO FRI. OVERALL QPF HAS INCREASED REGIONWIDE…WITH
AVERAGE AMTS OF AROUND AN INCH EXPECTED. SOME OF THIS WILL FALL AS
A WINTRY MIX ACROSS NORTHERN AREAS. HOWEVER…HIGHER AMTS COULD
OCCUR…PERHAPS AS MUCH AS 1.5 TO 2 INCHES…HIGHEST ACROSS
WESTERN NEW ENGLAND…THE EASTERN CATSKILLS AND POSSIBLY THE MID
HUDSON VALLEY REGION…WITH A GOOD PORTION OCCURRING AS RAIN.
SHOULD THESE HIGHER AMTS OCCUR…THEN MINOR FLOODING COULD OCCUR
ON SOME RIVERS/STREAMS ON FRIDAY. IN ADDITION…GIVEN THE
RELATIVELY FROZEN GROUND STILL ACROSS MUCH OF THE REGION…THERE
SHOULD BE LITTLE ROOM FOR ABSORPTION…WHICH WILL LIKELY LEAD TO
WIDESPREAD PONDING OF WATER IN LOW LYING…POOR DRAINAGE AND URBAN
AREAS…AND ON ROADWAYS SHOULD HEAVIER RAINFALL AMOUNTS OCCUR.

GENERALLY DRY CONDITIONS ARE THEN EXPECTED FOR SAT INTO SUNDAY.

&&

.ALY WATCHES/WARNINGS/ADVISORIES…
CT…NONE.
NY…WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST
FRIDAY FOR NYZ038-040-047-048-051-058-063.
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM EST
FRIDAY FOR NYZ032-033-039-041>043-082>084.
MA…WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST
FRIDAY FOR MAZ001-025.
VT…WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM EST
FRIDAY FOR VTZ013>015.

&&

$$
SYNOPSIS…NAS
NEAR TERM…NAS
AVIATION…BGM

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