February 11, 2013 Forecast Discussion

000
FXUS61 KALY 111153
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
653 AM EST MON FEB 11 2013

.SYNOPSIS…
LOW PRESSURE WILL MOVE FROM THE GREAT LAKES REGION INTO
SOUTHEASTERN CANADA TODAY…AS THE SYSTEMS WARM FRONT WILL BRING A
LIGHT WINTRY MIX OF PRECIPITATION TRANSITIONING TO RAIN THIS
AFTERNOON. A WEAK COLD FRONT WILL MOVE THROUGH TONIGHT TURNING
THE RAIN SHOWERS BACK TO SNOW SHOWERS ESPECIALLY NORTH AND WEST OF
THE CAPITAL REGION…WHERE LIGHT ACCUMULATIONS ARE EXPECTED.
BLUSTERY AND COLD CONDITIONS ARE EXPECTED ON TUESDAY WITH SNOW
SHOWERS PERSISTING NORTH AND WEST OF ALBANY…AS ANOTHER
DISTURBANCE MOVES THROUGH. HIGH PRESSURE WILL BUILD IN FROM THE
SOUTH AND WEST ON WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
A WINTER WEATHER ADVISORY CONTINUES FOR MIXED PRECIPITATION THIS
MORNING FROM THE MOHAWK VALLEY…CAPITAL REGION…SOUTHERN BERKSHIRES
SOUTH…AND A WINTER WX ADVISORY IS NOW IN EFFECT UNTIL 4 PM FOR THE
SOUTHERN ADIRONDACKS…LAKE GEORGE REGION…AND SRN VT.

AS OF 630 AM EST…THE COLUMN SATURATED QUICKLY OVER THE MID
HUDSON VALLEY…SRN TACONICS…ERN CATSKILLS…AND LITCHFIELD CTY
CT. WE HAVE HAD SOME SNOW REPORTED NEAR KPOU WITH LIKELY A HALF AN
INCH TO AN INCH. ANOTHER REPORT JUST CAME IN FROM SALT POINT WITH
A HALF AN INCH. WE INCREASED THE SNOW AMOUNTS TO A HALF AN INCH TO AN
INCH OVER THE MID HUDSON VALLEY. THE SALT POINT OBSERVER IS
REPORTING LIGHT FREEZING RAIN NOW. SOME OF THE SPOTTERS ARE
REPORTING LIGHT FREEZING RAIN WITH TEMPS 30-32F IN THE ERN
CATSKILLS. THE ONLY CHANGE IS TO ADD A BIT MORE SNOW. THE ADVISORY
STATEMENT SAYS A COATING TO AN INCH…SO THAT STILL SOUNDS GOOD IN
THESE AREAS.

A CLOSED COMPACT H500 CIRCULATION OVER THE UPPER
MIDWEST CONTINUES TO LIFT NORTHEAST INTO THE WRN GREAT LAKES
REGION…AND SRN ONTARIO THIS MORNING. THIS H500 CLOSED LOW IS
EMBEDDED WITHIN A BROADER MID LEVEL LONGWAVE TROUGH OVER THE NRN
ROCKIES AND NRN PLAINS. THE IMPRESSIVE COMMA HEAD WITH THE CYCLONE
ON THE WATER VAPOR LOOP PRODUCED THE BLIZZARD CONDITIONS IN THE
PLAINS THE OTHER DAY.

THE WARM FRONT TO THE STORM SYSTEM IS APPROACHING FROM THE OH
VALLEY…AND THE MID ATLANTIC REGION THIS MORNING. THERE IS ALSO A
WEAK THERMAL TROUGH AHEAD OF THE WARM FRONT WHICH IS ALLOWING THE
CLOUDS TO THICKEN AND LOWER. THE MID AND HIGH CLOUDS CONTINUE TO
STREAM IN…AND THE UPSTREAM RADARS FROM KENX CONTINUE TO HAVE A
LOT OF VIRGA DUE TO THE DRY AIR IN THE LOW LEVELS. SFC TEMP AND
DEWPT DIFFERENCES CONTINUE TO BE 10 TO 20 DEGREES OVER W-CNTRL
NY.

THE TREND FOR THE ONSET OF THE MIXED PCPN HAS BEEN SLIGHTLY SLOWED
DOWN. POPS ARE INCREASED TO LIKELY AND CATEGORICAL VALUES BTWN
12Z-14Z. A BLEND OF THE NAM AND GFS THERMAL/CRITICAL PARTIAL
THICKNESS FIELDS WERE USED IN THE GRIDS. THE BUFKIT SOUNDINGS FOR
KGFL/KPOU/KALB CONTINUE TO SHOW A BRIEF PERIOD OF PREDOMINANTLY
SLEET AND FREEZING RAIN TO RAIN FROM SOUTH TO NORTH IN THE LATE
MORNING INTO THE AFTERNOON. THE BEST CHANCE FOR PELLETS WILL BE
EARLY…BEFORE WE SATURATE. THE SFC HIGH IS MOVING OFF THE MID
ATLANTIC COAST…AND THIS IS NOT A CLASSIC COLD AIR DAMMING
SITUATION. WE EXPECTED LOCATIONS TO SATURATE OR COME CLOSE TO
SATURATE AND THEN TEMPS TO RISE…WITH THE INCREASING S/SW FLOW IN
THE LOW TO MID LEVELS. SLEET OR BRIEF SNOW ACCUMULATIONS WILL BE A
QUARTER OF AN INCH OR LESS FROM THE CAPITAL REGION SOUTH WITH
PERHAPS A HALF AN INCH TO AN INCH OVER THE MTNS.

THERE COULD BE AN INCH OR TWO OF SNOW OVER THE SRN DACKS…PARTS
OF THE LAKE GEORGE REGION…AND SRN VT BEFORE THE TRANSITION TO AN
ICY MIX. WE GENERALLY HAVE A COATING TO A TENTH OF AN INCH OF ICE
ACCRETION IN THE GRIDS. THERE COULD BE SLIGHTLY MORE OVER SRN VT
AND THE NRN BERKSHIRES. WE DON/T FEEL CONFIDENT ANYONE WILL GET A
QUARTER OF AN INCH. BESIDES THE LOW LEVEL COLD AIR BEING
POTENTIALLY ERODED QUICKLY…THE QPF JUST DOESN/T LOOK HEAVIEST
ENOUGH TOO. WE USED THE LATEST HPC QPF…AND BY 00Z/TUE…WE HAVE
ABOUT TWO TENTHS OF AN INCH TO A THIRD OF AN INCH BASED HEAVILY ON
THE LATEST HPC QPF.

TEMPS SHOULD WARM QUICKLY ABOVE FREEZING FROM THE CAPITAL
REGION…MOHAWK VALLEY…AND BERKSHIRES SOUTH. THE NRN TIER SHOULD
RISE ABOVE FREEZING IN THE EARLY PM. WE TRIMMED BACK THE TIME TO
THE NRN TIER ADVISORY TO 4 PM. THE SNOWPACK COULD KEEP TEMPS DOWN
A BIT…BUT THIS WILL BE A PRETTY GOOD SURGE OF WARM ADVECTION.
THE ENTIRE FCST AREA SHOULD GET INTO A MINI WARM SECTOR BY THE MID
TO LATE PM…BUT THEN A WEAK COLD FRONT WILL BE APPROACHING EARLY
THIS EVENING.

SOME OF THE SCT RAIN SHOWER SHOWERS OVER THE WRN DACKS…WILL
TRANSITION BACK TO SNOW SHOWERS WITH THE WEAK COLD FRONT MOVING
THROUGH…AND THE INTENSE CYCLONE MOVING ACROSS SRN ONTARIO INTO
QUEBEC.

EXPECT MAX TEMPS TO BE IN THE U30S TO L40S FROM THE MOHAWK
VALLEY…CAPITAL REGION…SRN VT SOUTH AND EAST…WITH MAINLY MID
AND U30S TO THE NORTH.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/…
TONIGHT…THE STRONG CYCLONE MOVES INTO SW QUEBEC. THE CYCLONIC
VORTICITY ADVECTION ASSOCIATED WITH THE CLOSED UPPER LOW WILL
FOCUS SOME SNOW SHOWERS ALONG THE WRN SPINE OF THE SRN DACKS…AND
EASTWARD ALONG THE SRN GREENS. WE ARE EXPECTING 1 TO 4 INCHES OF
SNOW IN PORTIONS OF HERKIMER AND HAMILTON COUNTIES. AN INCH OR SO
IN SRN VT…PERHAPS SOME COATINGS TO HALF INCH AMOUNTS IN THE
CENTRAL MOHAWK VALLEY… AND NRN CATSKILLS. LITTLE OR NO
ACCUMULATION IN THE CAPITAL REGION. THE WIND WILL START TO
INCREASE PRIOR TO DAYBREAK FROM THE W/SW AT 15 TO 25 MPH WITH SOME
GUSTS AROUND 35 MPH WITH THE PASSAGE OF THE FRONT. EXPECT LOWS IN
THE MID 20S TO L30S.

TUESDAY…STRONG COLD ADVECTION SWEEPS ACROSS THE REGION WITH THE
PASSAGE OF THE SECONDARY COLD FRONT/SFC TROUGH WITH LOW PRESSURE
DEEPENING AND INTENSIFYING NEAR NEW BRUNSWICK. THE STRONG
HORIZONTAL SFC PRESSURE GRADIENT BTWN THE CYCLONE…AND HIGH
PRESSURE OVER TN VALLEY COUPLED WITH GOOD MIXING WILL YIELD
BLUSTERY AND COLD CONDITIONS WITH ISOLD-SCT SNOW SHOWERS
ESPECIALLY NORTH AND WEST OF THE CAPITAL. WE MAY COME CLOSE TO 3-6
INCHES OF SNOW FOR NRN HERKIMER COUNTY MON NIGHT-TUE. A WINTER WX
ADVISORY MAY BE NEEDED FOR THE WRLY UPSLOPE SNOWS. WE WILL MAKE
MENTION IN THE HWO.

THE BEST WINDS AT H925 /40-50 KTS/ ARRIVE IN THE MORNING. THE
BETTER MIXING WILL BE IN THE AFTERNOON. NONETHELESS…WE HAVE WEST
WINDS OF 15 TO 30 MPH…WITH SOME GUSTS AROUND 40 MPH. THE BEST
WINDS WILL BE DUE TO THE FUNNELING DOWN THE MOHAWK RIVER VALLEY
INTO THE CAPITAL REGION…AND BERKSHIRES. H850 TEMPS DROP TO -10C
BY THE AFTERNOON OVER THE FCST AREA. MAX TEMPS MAY OCCUR AROUND
NOON…AND THEN DROP OFF. WE SIDED CLOSER TO THE MAVMOS TEMPS.
EXPECT HIGHS IN THE U30S TO L40S IN THE VALLEYS…AND U20S TO M30S
OVER THE HIGHER TERRAIN.

TUESDAY NIGHT…THE WINDS WILL GRADUALLY DIMINISH…AND THE W/NW
FLOW MAY FOCUS A BRIEF PERIOD OF LAKE EFFECT SNOW SHOWERS AND
FLURRIES FOR THE WRN DACKS…MOHAWK VALLEY…AND NRN CATSKILLS.
SOME SLIGHT OR LOW CHC POPS WERE USED THERE. THE FLOW STARTS TO
BECOME ANTICYCLONIC BY DAYBREAK WITH HIGH PRESSURE BUILDING IN
FROM THE SOUTH. THE SKIES WILL CLEAR…WITH LOWS IN THE TEENS AND
L20S.

WEDNESDAY…HIGH PRESSURE NUDGES IN FROM THE OHIO VALLEY…AND MID
ATLANTIC REGION WITH SOME SUNSHINE AND SEASONABLE TEMPS. A
DISTURBANCE APPROACHES FROM THE PEIDMONT REGION…AND MID ATLANTIC
STATES MAY BRING SOME LIGHT SNOW TO REGION DURING THE NIGHT TIME
PERIOD…THOUGH THE GUIDANCE IS IN DISAGREEMENT HOW FAR NORTH THE
STORM TRACKS.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/…
A SOUTHERN STREAM LOW PRESSURE SYSTEM BEGINS TO TAKE SHAPE OVER THE
SOUTHEASTERN UNITED STATES DURING THE DAY WEDNESDAY. THIS STORM IS
FORECAST TO DEEPEN AS IT MOVES NORTHEASTWARD OFF THE COAST WEDNESDAY
NIGHT. THE GFS IS A BIT DEEPER WITH THE LOW AND ABOUT 150 TO 200
MILES TO THE NORTHWEST OF THE ECMWF`S TRACK. THE ECMWF IS ON THE
EASTERN SIDE OF THE GFS ENSEMBLE SPREAD. BASED ON THE ECMWF TRACK
THE NORTHERN EDGE OF THE PRECIPITATION SHIELD WOULD BRUSH THE NEW
YORK CITY METRO AREA AND LONG ISLAND WHERE AS THE GFS BRINGS THE
NORTHERN EDGE INTO THE EASTERN CATSKILLS…MID HUDSON VALLEY AND
NORTHWESTERN CONNECTICUT. THE GEFS PLUMES INDICATE QUITE A SPREAD IN
THE POTENTIAL START TIME OF PRECIPITATION AND QPF AMOUNTS. BOTH THE
ECMWF AND GFS CAME IN WITH A STRONGER SURFACE LOW THIS RUN WITH THE
00Z/ECMWF MORE IN LINE WITH THE 18Z/GFS. AT THIS TIME HAVE CHANCE
POPS FOR LIGHT SNOW FOR THE MID HUDSON VALLEY AND NORTHWESTERN
CONNECTICUT WITH SLIGHT CHANCE ACROSS THE REST OF THE FORECAST AREA.

NORTHERN STREAM ENERGY WILL BE IN THE HEELS OF THE SOUTHERN STREAM
SYSTEM BRINGING A LOW PRESSURE SYSTEM ACROSS THE GREAT LAKES REGION
THURSDAY AND PASSING IT TO OUR NORTH ACROSS EASTERN CANADA THURSDAY
NIGHT. THIS LOW WILL BE SLOW TO MOVE AWAY FROM THE REGION SO HAVE
LINGERING POPS INTO FRIDAY.

UNCERTAINTY IN THE FORECAST REALLY GROWS AS WE HEAD INTO THE
WEEKEND. MODEL GUIDANCE IS IN AGREEMENT THAT THE LONGWAVE PATTERN
AMPLIFIES WITH THE TROUGH DIGGING OVER THE EASTERN UNITED STATES AS
ENERGY DIVES OUT OF CENTRAL CANADA. INDICATIONS ARE A COASTAL LOW
WILL DEVELOP SOMEWHERE OFF THE EAST COAST OVER THE WEEKEND. FOLLOW
HPC`S LEAD AND KEEP THE FORECAST SIMPLE WITH LOW CHANCE POPS FOR
LIGHT SNOW. REFER TO THE EXTENDED FORECAST DISCUSSION (PMDEPD)
ISSUED BY THE HYDROMETEOROLOGICAL PREDICTION CENTER FOR MORE DETAILS
ABOUT THE MODELS AND THEIR DIFFERENCES.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/…
A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE GREAT LAKES TODAY WITH
ITS ASSOCIATED WARM FRONT MOVING INTO OUR AREA TODAY FOLLOWED BY ITS
ASSOCIATED COLD FRONT LATER IN THE DAY.

CONDITIONS WILL CONTINUE TO LOWER TO MVFR AS A WINTRY MIX OF
PRECIPITATION OVERSPREADS THE AREA. INITIAL THE PRECIPITATION HAS
BEEN MAINLY IN THE FORM OF SNOW AND SLEET. A TRANSITION TO FREEZING
RAIN WILL OCCUR FOR A PERIOD THIS MORNING BEFORE SURFACE TEMPS WARM
ENOUGH FOR PLAIN RAIN. THIS TRANSITION WILL HAPPEN QUICKEST AT KPOU
WITH RAIN EXPECTED BY MID MORNING. RAIN IS EXPECTED AT KALB AND
KPSF MIDDAY AND KGFL EARLY AFTERNOON. THE RAIN SHOULD THEN PERSIST
WELL INTO THE AFTERNOON.

WITH THE WARMER AIR OVER THE SNOWPACK WILL HAVE FOG TODAY. WITH THE
PASSAGE OF THE COLD FRONT WINDS WILL SHIFT TO THE WEST AND MIXED THE
ATMOSPHERE DISSIPATING THE FOG.

SOUTHERLY FLOW THIS MORNING WILL SHIFT MORE TO THE SOUTHWEST THIS
AFTERNOON WITH A SHIFT TO THE WEST WITH THE PASSAGE OF A COLD FRONT.
WIND WILL BE GUSTY AT KALB.

HAVE LOW LEVEL WINDS IN THE TAFS AS WINDS AROUND 2000 FEET AGL
INCREASE WILL BE FROM SOUTH TO SOUTHWEST AT 35 TO 40 KNOTS INTO THIS
AFTERNOON.

OUTLOOK…
TUE…VFR/MVFR. CHC -SHSN KGFL…KALB AND KPSF.
WED…VFR. NO SIG WX.
WED NIGHT…MAINLY VFR. CHC -SN KPOU. OTHERWISE SLIGHT CHC.
THU…VFR. NO SIG WX.
FRI…VFR/MVFR. CHC -SN AND -RA.

&&

.HYDROLOGY…
NO HYDRO PROBLEMS ARE EXPECTED THE NEXT 5 DAYS.

A WINTRY MIX TODAY WILL HAVE LITTLE IMPACT ON THE WATERWAYS. TOTAL
QPF BASED ON THE HPC DATA UTILIZED WILL BE IN THE TWO TENTHS TO
THIRD OF AN INCH RANGE. TEMPS WILL BRIEFLY WARM ABOVE FREEZING
TODAY WITH MID 30S TO LOWER 40S.

COLDER AIR WILL RETURN TONIGHT INTO TUESDAY WITH THE MAIN PTYPE
SNOW. SCT TO NUMEROUS SNOW SHOWERS WILL PERSIST OVER THE WRN
DACKS…AND SRN GREENS.

A STORM SYSTEM PASSING SOUTH OF LONG ISLAND MAY BRING SOME SNOW
SOUTH OF THE CAPITAL REGION WED NIGHT INTO THU. SEASONABLE TEMPS AND
DRY WEATHER RETURNS TO CLOSE THE WEEK.

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 UNTIL NOON EST TODAY FOR CTZ001-013.
NY…WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NYZ038>040-
047>054-058>061-063>066.
WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
NYZ032-033-041>043-082>084.
MA…WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR MAZ025.
WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
MAZ001.
VT…WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
VTZ013>015.

&&

$$
SYNOPSIS…WASULA
NEAR TERM…WASULA
SHORT TERM…WASULA
LONG TERM…IAA
AVIATION…IAA
HYDROLOGY…WASULA

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