January 16, 2012 Forecast Discussion

000
FXUS61 KALY 162140
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
440 PM EST MON JAN 16 2012

.SYNOPSIS…
LOW PRESSURE WILL APPROACH FROM THE LOWER GREAT LAKES REGION
TONIGHT…WITH A LIGHT WINTRY MIX OF PRECIPITATION MOVING INTO THE
REGION AHEAD OF A WARM FRONT. THE MIXED PRECIPITATION WILL
TRANSITION TO RAIN BY LATE TOMORROW MORNING INTO THE EARLY
AFTERNOON…AS THE WARM FRONT MOVES NORTH OF THE REGION. THE COLD
FRONT TO THE SYSTEM WILL QUICKLY MOVE ACROSS EASTERN NEW YORK AND
WESTERN NEW ENGLAND TUESDAY NIGHT…WITH SCATTERED SNOW
SHOWERS…BLUSTERY…AND COLD CONDITIONS FOR WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/…
AS OF 400 PM EST…HIGH PRESSURE CONTINUES TO RETREAT OFF THE MID
ATLANTIC COAST THIS AFTERNOON…AS LOW PRESSURE WILL BE
APPROACHING FROM THE CNTRL MS RIVER VALLEY EARLY THIS EVENING IN
THE QUASI-ZONAL MID LEVEL FLOW ALOFT. THE SFC WAVE WILL QUICKLY MOVE
TOWARDS THE LOWER GREAT LAKES REGION OVERNIGHT…WITH ITS WARM
FRONT BRINGING A PERIOD OF MIXED PRECIPITATION.

THE LATEST GFS/NAM CRITICAL PARTIAL THICKNESSES INDICATE AN ONSET
OF LIGHT SNOW AND SLEET FROM THE CAPITAL REGION SOUTH PRIOR TO
MIDNIGHT. IT WILL TAKE A FEW HOURS FOR THE COLUMN TO SATURATE WITH
THE LARGE SFC TEMP-DEWPT SPREADS. THE NAM IS LIKELY A LITTLE TOO
FAST WITH THE WARM ADVECTION PCPN BTWN 00Z-03Z. WE EXPECT THE
CLOUDS TO THICKEN AND LOWER EARLY THIS EVENING WITH THE MODEST
ISENTROPIC LIFT ON THE 295K SFC GENERATING THE SNOW AND SLEET
INITIALLY. THE 850-700 HPA 1540 METER LINE QUICKLY MOVES NORTH
ACROSS THE REGION AFTER MIDNIGHT WITH THE PRECIPITATION
TRANSITIONING FIRST TO A MIXTURE OF SLEET AND FREEZING RAIN FROM
THE CAPITAL REGION SOUTH PRIOR TO 12Z. THE NAM/GFS BUFKIT PROFILES
AND NAM BUFFER SOUNDINGS SUPPORT A TRANSITION TO SOME FREEZING
RAIN. THE SOUNDING PROFILES ARE ISOTHERMAL OVERNIGHT…WHERE PCPN
INTENSITY WILL PLAY A ROLE WHETHER IT REMAINS SNOW OR SLEET…OR
GOES TO FREEZING RAIN. THE SYNOPTIC FORCING OR QG LIFT IS NOT
STRONG…AND WE DO NOT EXPECT A DEEP FETCH OF MOISTURE WITH THE
W/SOUTHWEST FLOW ALOFT. THE NRN TIER WILL CONTINUE TO HAVE SOME
SLEET AND SNOW BTWN 06Z-12Z…AGAIN WE ARE EXPECTING LIGHT AMOUNTS
OF SNOW AND SLEET ACROSS THE ENTIRE REGION PRIOR TO DAYBREAK WITH
A COATING TO A COUPLE OF INCHES…COUPLED WITH A COATING TO A TENTH
OF AN INCH ICE. THE HIGHER SNOW TALLIES WILL LIKELY BE OVER THE
BERKSHIRES…SRN DACKS…AND THE LITCHFIELD HILLS WHERE 2 TO 3
INCHES WILL BE POSSIBLE. THE LATEST NAM SHOWS THE WARM NOSE ON THE
MODEL SOUNDINGS OVER KPOU INCREASING TO GREATER THAN 3C FOR A
TRANSITION TO LIGHT FREEZING RAIN TO PLAIN RAINFALL TOWARDS
12Z…AS THE SFC TEMPS CLIMB ABOVE FREEZING. THE HIGHEST SREF
PROBABILITIES OF FREEZING RAIN CONTINUE TO BE OVER THE ERN
CATSKILLS…MID HUDSON VALLEY…AND PARTS OF THE MOHAWK
VALLEY/CAPITAL REGION. THE LATEST 12Z GEFS ALY PLUME DIAGRAM
PREDOMINANTLY HAS A SNOW TO RAIN TRANSITION BY DAYBREAK WITH A FEW
-FZRA MEMBERS.

TEMPERATURES WILL SLOWLY RISE OVERNIGHT FROM EARLY MINS IN THE
UPPER TEENS OVER THE SRN DACKS…AND THE LOWER TO M20S ELSEWHERE.
IT IS POSSIBLE TEMPS WILL WET BULB SOMETIME OVERNIGHT…AND THEN
RISE. OVERALL…WE USED A NON-DIURNAL TREND WITH MIN VALUES WELL
BEFORE MIDNIGHT. EVEN WITH A LIGHT MIXED PCPN EVENT…THE MORNING
COMMUTE COULD BE SLIPPERY AND DIFFICULT. WE WILL BE KEEPING THE
WINTER WEATHER ADVISORIES IN PLACE.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/…
TOMORROW…THE LIGHT WINTRY MIX OF -SN/-IP/-FZRA SHOULD QUICKLY
TRANSITION TO ALL RAIN FROM SOUTH TO NORTH DURING THE MORNING.
THERE COULD BE SOME POCKETS OF -FZRA/-IP OVER THE SRN DACKS…LAKE
GEORGE REGION…AND SRN VT THAT LINGER SHORTLY AFTER NOONTIME. WE
KEPT THE NRN ADVISORY FROM THE WRN MOHAWK VALLEY…LAKE GEORGE
REGION…AND SRN VT UNTIL 19Z FOR NOW…THOUGH THE LATEST TRENDS
INDICATE MOST OF THESE LOCATIONS COULD RISE ABOVE BTWN NOON-3 PM.
THE LOW-LEVEL COLD AIR MAY HANG ON THE LONGEST IN THE NRN ZONES BASED ON
THE SOUNDING PROFILES. FURTHER SOUTH…AFTER A SLIPPERY AND
TRICKY COMMUTE THE PCPN WILL CHANGE TO LIGHT RAIN FIRST IN THE MID
HUDSON VALLEY…CAPITAL REGION…TACONICS AND ERN CATSKILLS BY THE
LATE MORNING…AS THE SFC CYCLONE MOVES NORTH OF LAKE ERIE BY
NOONTIME…AS WARMER AIR MOVES OVER THE REGION FROM THE SOUTH AND
WEST. EXPECT H850 TEMPS ACCORDING TO GFS/NAM TO GET TO +2 TO +4C
OVER THE REGION BY 18Z. THE H925 TEMPS ALSO RISE ABOVE FREEZING
SHORTLY AFTER 18Z. A WEAK IMPULSE IN THE WARM SECTOR TO THE SYSTEM
WILL KEEP SOME LIGHT RAIN OR DRIZZLE AROUND DURING THE AFTERNOON.
IT LOOKS LIKE A PREFRONTAL TROUGH AHEAD OF THE MAIN COLD FRONT
THAT COULD REKINDLE THE PCPN IN THE LATE PM AND EARLY EVENING. WE
KEPT POPS AT LIKELY AND CATEGORICAL VALUES DURING THE PM. MAX
TEMPS WILL GENERALLY BE IN THE M30S TO L40S ACROSS THE REGION. THE
MID HUDSON VALLEY/SRN LITCHFIELD CTY MAY HAVE A FEW M40S. THE
COLD FRONT WILL BE APPROACHING DURING THE OVERNIGHT PERIOD.

TUESDAY NIGHT…THE SFC CYCLONE DEEPENS AND INTENSIFIES…AS IT
MOVES NORTH OF THE ST LAWRENCE RIVER VALLEY…ACROSS SRN QUEBEC.
THE 850 HPA WINDS INCREASE TO 50-60 KTS AROUND 06Z…AND THE 925
HPA WINDS CRANK UP TO 40-50 KTS. A WIND ADVISORY MAY BE NEEDED AFTER
MIDNIGHT THROUGH THE WEDNESDAY MORNING…IF WE CAN TRANSLATE SOME
OF THE 40 KT GUSTS TO THE SFC. IT WILL BE BLUSTERY…AS THE COLD
FRONT SWINGS THROUGH TUE NIGHT. EXPECT W/NW WINDS OF 15-30 MPH
WITH SOME GUSTS IN THE 35-45 MPH RANGE. WE WILL CONTINUE TO
HIGHLIGHT A WIND ADVISORY POSSIBILITY LATE TUE NIGHT/WED MORNING
IN THE HWO. IMPRESSIVE COLD AIR ADVECTION OCCURS OVER THE FCST
AREA TUE NIGHT WITH H850 TEMPS FALLING TO -10C TO -15C OVER THE BULK
OF THE REGION. OUR MAX TEMPS MAY OCCUR TOWARDS DAYBREAK ON WED.
THERE WILL BE A BURST OF SNOW SHOWERS WITH THE FRONT…AND THEN
SOME WESTERLY OR OROGRAPHIC UPSLOPE SNOWFALL WILL KICK IN OVER THE
WRN DACKS…THE SRN GREENS…AND POSSIBLY THE NRN TACONICS…AND
NRN BERKS. A BURST OF HEAVIER SNOW IS ALSO POSSIBLE OVER THE WRN
MOHAWK VALLEY. RIGHT NOW…WE HAVE ABOUT 1 TO 3 INCHES OF SNOW IN
THESE AREAS. THE BIGGEST DIFFERENCE WITH THIS POTENTIAL UPSLOPE
EVENT…AND THE ONE FROM LAST FRI…IS THAT WE ARE DEALING WITH A
PROGRESSIVE OPEN WAVE IN SW FLOW…AND THE H500 CIRCULATION DOES
NOT CLOSE OFF TO THE N/NE. WE WILL CONTINUE TO MONITOR THE UPSLOPE
POTENTIAL HERE. LOWS WILL RANGE FROM THE TEENS AND LOWER 20S NORTH
AND WEST OF THE CAPITAL REGION WITH MID AND U20S SOUTH AND
EAST…EXCEPT A FEW L30S OVER THE MID HUDSON VALLEY.

WEDNESDAY…THE STRONG COLD AIR ADVECTION CONTINUES OVER THE
REGION. THE THREAT WILL CONTINUE INTO THE EARLY PM OF SOME 40 TO
PERHAPS EVEN 50 MPH WINDS…WITH A DEEPER MIXING POTENTIAL. THE
CYCLONE CONTINUES TO DEEPEN AND INTENSIFY OVER THE CANADIAN
MARITIMES. WE KEPT SOME UPSLOPE SNOW SHOWERS IN FOR THE WRN
DACKS..AND SRN GREENS UNTIL AT LEAST NOONTIME. THERE WILL BE A
WEAK LAKE EFFECT CONNECTION…BUT THE INVERSION QUICKLY LOWERS BY
THE LATE MORNING/EARLY PM AS THE SFC-BOUNDARY LAYER WINDS VEER TO
THE NORTHWEST. THE BEST CHANCE OF SNOW SHOWERS WILL BE FROM THE
CAPITAL REGION…NRN TACONICS…AND BERKSHIRES NORTH AND WEST.
A FEW NARROW MULTIBANDS MAY NUDGE INTO THE ERN CATSKILLS/WRN
MOHAWK VALLEY. H850 TEMPS FALL TO ABOUT -15 TO -20C FROM THE
CAPITAL REGION NORTH AND WEST. EXPECT TEMPS TO FALL INTO THE
TEENS AND LOWER 20S…AFTER EARLY MID TO LATE MORNING HIGHS IN
THE M20S TO L30S…ESPECIALLY IN THE VALLEY LOCATIONS. IT WILL BE
A BLUSTERY AND VERY COLD DAY !

WEDNESDAY NIGHT…THE WINDS QUICKLY SUBSIDE WITH COLD CANADIAN
HIGH BUILDING IN OVER NY AND NEW ENGLAND. IT WILL BE A FRIGID
NIGHT WITH MINS OF ZERO TO 15 BELOW FROM THE LAKE GEORGE
REGION/SRN GREENS NORTH AND WEST…AND SINGLE DIGITS
ELSEWHERE…EXCEPT OVER THE MID HUDSON VALLEY WHERE SOME LOWER
TEENS ARE POSSIBLE.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/…
THE LONG TERM PERIOD IS EXPECTED TO START OUT COLD AND END UP RATHER
MILD.

THURSDAY-THURSDAY NIGHT…A CLIPPER TYPE SYSTEM IS EXPECTED TO TRACK
ACROSS THE UPPER GREAT LAKES THURSDAY MORNING AND MOVE JUST NORTH OF
THE SAINT LAWRENCE RIVER VALLEY THURSDAY NIGHT. AT THIS TIME EXPECT
MAINLY LIGHT SNOW AS IT APPEARS THAT IF ANY COASTAL REDEVELOPMENT
OCCURS IT WILL BE TOO FAR SOUTH AND EAST OF FA TO HAVE MUCH OF AN
IMPACT ON OUR AREA. EXPECT HIGHS ON THURSDAY TO RANGE FROM THE UPPER
TEENS NORTHWEST TO AROUND 30 SOUTHEAST. LOWS THURSDAY NIGHT ARE
EXPECTED TO BE COLD AS MUCH COLDER AIR SWEEPS IN IMMEDIATELY BEHIND
THE CLIPPER SYSTEM WITH TEMPS RANGING FROM AROUND ZERO NORTHWEST TO
MID TEENS SOUTHEAST.

FRIDAY…HIGH PRESSURE BUILDS IN QUICKLY ON FRIDAY BEHIND THE
CLIPPER TYPE SYSTEM AND FLOW IS EXPECTED TO BECOME ANTICYCLONIC
LIMITING LAKE EFFECT POTENTIAL. EXPECT HIGHS ON FRIDAY TO RANGE FROM
THE UPPER TEENS NORTHWEST TO AROUND 30 SOUTHEAST.

FRIDAY NIGHT AND SATURDAY…A GREAT DEAL OF UNCERTAINTY EXISTS
DURING THIS PERIOD AS DIFFERENCES EXIST NOT ONLY IN AMPLITUDE OF THE
H5 TROF BUT ORIENTATION AS WELL WITH SURFACE WAVE TRACKING THROUGH
THE MIDDLE ATLANTIC PERIOD WITH GFS CONSIDERABLY FASTER THAN THE
ECMWF AND GGEM WITH TRACK OF THIS SYSTEM. QPF AMOUNTS ALSO VARY GREATLY
WITH ECMWF HAVING QPF AMOUNTS RANGING FROM A QUARTER OF AN INCH
NORTHWEST TO TWO THIRDS OF AN INCH SOUTHEAST…WHILE THE GFS HAS
ONLY A FEW HUNDREDTHS OF AN INCH AND THE GGEM HAS A LITTLE OVER A
TENTH OF AN INCH IN MOST AREAS DURING THIS PERIOD. FOR NOW WILL GO
SLIGHT CHANCE TO CHANCE POPS WITH HIGHEST VALUES SOUTHERN TWO THIRDS
OF FA ON SATURDAY. IT DOES APPEAR TO BE COLD ENOUGH FOR MAINLY SNOW
EXCEPT FOR THE POSSIBILITY OF RAIN MIXED WITH SNOW FAR SOUTHEAST
SATURDAY AFTERNOON. EXPECT LOWS FRIDAY NIGHT TO RANGE FROM A FEW
DEGREES BELOW ZERO NORTHWEST TO MID TEENS SOUTHEAST WITH HIGHS ON
SATURDAY IN THE MID 20S NORTHWEST TO MID 30S SOUTHEAST.

SATURDAY NIGHT AND SUNDAY ARE EXPECTED TO BE MAINLY DRY AS A RIDGE
OF HIGH PRESSURE BUILDS INTO THE AREA ON SUNDAY WITH MILDER
CONDITIONS EXPECTED. ANY LINGERING PCPN ASSOCIATED WITH THE MID
ATLANTIC SYSTEM WOULD BE MAINLY CONFINED TO THE SOUTHEAST CORNER OF
THE FA SATURDAY EVENING. EXPECT LOWS SATURDAY NIGHT TO RANGE FROM
THE MID TEENS NORTHWEST TO UPPER 20S SOUTHEAST WITH HIGHS ON SUNDAY
RANGING FROM THE MID 30S NORTHWEST TO MID 40S SOUTHEAST.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/…
VFR CONDITIONS WILL CONTINUE THROUGH THE EARLY EVENING HOURS WITH
LIGHT WINDS. HIGH LEVEL CIRRUS CLOUDS WILL CONTINUE TO INCREASE OVER
THE REGION THROUGH THE AFTN AND EARLY EVENING.

WEAK ISENTROPIC LIFT WILL LEAD TO A PERIOD OF VERY LIGHT
PRECIPITATION OVERNIGHT. THE PRECIP MAY BEGIN AS EARLY AS 03Z FOR
KALB/KPOU AND BY 06Z FOR KGFL AND WILL BE IN THE FORM OF THE SNOW.
HOWEVER…AS WARMER AIR ALOFT MOVES INTO THE REGION…SOME SLEET MAY
MIX IN WITH THE SNOW FOR THE SECOND HALF OF THE NIGHT FOR
KALB/KPOU. IT/S POSSIBLE EVEN A BRIEF PERIOD OF FZRA MAY MIX AS
WELL…ALTHOUGH CURRENT BUFR SOUNDING SEEM TO INDICATE MORE
SNOW/SLEET WILL OCCUR…SO WILL LEAVE ANY FZRA OUT OF TAF AT THIS
TIME. FURTHER NORTH…THE COLDER AIR MASS IN PLACE WILL KEEP MOST OF
THE PRECIP OVERNIGHT AT KGFL AS MAINLY SNOW. FLYING CONDITIONS WILL
GENERALLY BE MVFR…AS THE PRECIP WILL BE FAIRLY LIGHT IN
INTENSITY…SO VSBYS/CIGS SHOULDN/T DETERIORATE FULLY. WHILE WE
CANNOT TOTALLY RULE OUT IFR…AT THIS POINT…CONFIDENCE IS LOW AT
WHEN/HOW LONG IFR WOULD OCCUR…SO WILL KEEP OUT OF THE TAF AT THIS
TIME. WINDS OVERNIGHT WILL CONTINUE TO BE LIGHT FROM A SOUTHERLY
DIRECTION. SLEET/SNOW WILL PROBABLY ONLY AMOUNT TO AN INCH OR LESS
OVERNIGHT.

SFC TEMPS WILL BE RISING ABOVE FREEZING BY JUST BEFORE SUNRISE AT
KPOU…AROUND SUNRISE AT KALB…AND BY 14Z AT KGFL. HOWEVER…THE
REGION WILL PROBABLY BE IN A DRY SLOT BY THAT TIME…SO ANY SPOTTY
PRECIP WILL BE JUST LIGHT RAIN SHOWERS FOR THE TUESDAY MORNING
HOURS. HOWEVER…THE LINGERING LOW LEVEL MOISTURE MAY STILL ALLOW
FOR LOW STRATUS AND SOME MIST…SO MVFR FLYING CONDITIONS WILL
CONTINUE THROUGH THE MORNING HOURS. WINDS WILL CONTINUE TO BE RATHER
LIGHT.

OUTLOOK…
TUE…MVFR/IFR…-SHRA LIKELY.
TUE NIGHT…MVFR WITH IFR POSSIBLE…CHANCE OF -SHRA/-SHSN.
WED…VFR…WINDY. SLIGHT CHC -SHSN.
WED NIGHT…VFR…NO SIG WX.
THU…MAINLY VFR…SLIGHT CHC -SHSN WITH MVFR POSSIBLE.
FRI…VFR. NO SIG WX.

&&

.HYDROLOGY…
NO MAJOR PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS OVER THE NEXT
5 DAYS.

A LIGHT MIXED PRECIPITATION EVENT WILL OCCUR OVERNIGHT INTO
TUESDAY WITH TOTAL QPF GENERALLY UNDER A QUARTER OF AN INCH. A
COLD FRONT WILL MOVE THROUGH WITH SOME SCATTERED SNOW SHOWERS WITH
LIGHT LIQUID EQUIVALENT AMOUNTS WELL UNDER A QUARTER OF AN INCH.
THE HIGHEST SNOW TALLIES WILL BE ALONG THE WESTERN SLOPES OF THE
SOUTHERN ADIRONDACKS…AND THE SOUTHERN GREEN MOUNTAINS TUESDAY
NIGHT INTO WEDNESDAY. COLD AND DRY WEATHER WILL PREVAIL LATE
WEDNESDAY THROUGH THURSDAY. A CLIPPER LOW MAY BRING SOME LIGHT
SNOW THURSDAY NIGHT INTO FRIDAY.

ICE FORMATION OR THICKENING WILL SLOW DOWN TONIGHT THROUGH TUESDAY
WITH A BRIEF SPELL OF MILDER WEATHER. ICE FORMATION SHOULD
INCREASE AGAIN WEDNESDAY INTO THURSDAY AS TEMPERATURES FALL BACK
WELL BELOW FREEZING.

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…WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 AM EST
TUESDAY FOR CTZ001-013.
NY…WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 AM EST
TUESDAY FOR NYZ047>054-058>061-063>066.
WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 2 PM EST
TUESDAY FOR NYZ032-033-038>043-082>084.
MA…WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 AM EST
TUESDAY FOR MAZ001-025.
VT…WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 2 PM EST
TUESDAY FOR VTZ013>015.

&&

$$
SYNOPSIS…WASULA
NEAR TERM…WASULA
SHORT TERM…WASULA
LONG TERM…11
AVIATION…FRUGIS
HYDROLOGY…KL/WASULA

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