November 27, 2013 Forecast Discussion

000
FXUS61 KALY 272135
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
435 PM EST WED NOV 27 2013

.SYNOPSIS…
LOW PRESSURE WILL DEEPEN AS IT TRACKS NORTHEASTWARD INTO THE
CANADIAN MARITIMES TONIGHT. AS A RESULT…COLDER AIR WILL FILTER
INTO THE REGION WITH A GUSTY NORTHWEST WIND DEVELOPING. STEADY
PRECIPITATION WILL CHANGE TO ALL SNOW THIS EVENING BEFORE ENDING.
COLD AND BREEZY CONDITIONS EXPECTED THROUGH THANKSGIVING…WITH LAKE
EFFECT SNOW SHOWERS MAINLY WEST OF THE CAPITAL REGION. BELOW NORMAL
TEMPERATURES WILL PERSIST INTO THE FIRST HALF OF THE WEEKEND…WITH
GENERALLY DRY CONDITIONS FRIDAY INTO SATURDAY DUE TO HIGH PRESSURE
BUILDING IN.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/…
AS OF 430 PM EDT…PRECIPITATION HAS INCREASED ACROSS MUCH OF THE
AREA LATE THIS AFTERNOON…AS ONE MORE SURGE OF MOISTURE TIED TO A
POTENT SHORT WAVE JUST AHEAD OF THE MAIN UPPER LEVEL TROUGH AXIS
OVER THE MID ATLANTIC REGION LIFTS NORTHWARD. SO WILL MENTION
CATEGORICAL POPS THROUGH THE EARLY EVENING HOURS BEFORE GRADUALLY
TAPERING OFF OVERNIGHT. COLD ADVECTION HAS COMMENCED ACROSS THE
ENTIRE AREA…WITH PRECIP GRADUALLY CHANGING FROM RAIN TO SNOW FROM
AROUND THE CAPITAL REGION SOUTH AND EAST. TEMPERATURES STILL IN THE
MID TO UPPER 30S…SO GENERALLY A MIX OF RAIN/SNOW OCCURRING IN
THESE LOCATIONS…WITH ALL SNOW FARTHER BACK TO THE WEST ACROSS THE
MOHAWK VALLEY…WESTERN SOUTHERN ADIRONDACKS AND EASTERN CATSKILLS.

AS THE BOUNDARY LAYER CONTINUES TO COOL THIS EVENING…THERE WILL BE
A POTENTIAL FOR SOME MINOR SNOW ACCUMULATIONS. ROADS COULD GET SLICK
WHERE NOT TREATED. GENERALLY EXPECTING LESS THAN AN INCH…EXCEPT 1
TO 3 INCHES OVER THE HIGHER TERRAIN SUCH AS THE ADIRONDACKS AND
SOUTHERN GREEN MOUNTAINS OF VERMONT. TRICKY CALL WITH REGARDS TO
VALLEY LOCATIONS DUE TO INITIALLY WET GROUND…BUT WILL FORECAST A
SLUSHY INCH OR SO OF ACCUMULATION.

STEADY SNOW SHOULD TAPER OFF TO SNOW SHOWERS BY LATE EVENING…AS
THE MAIN FORCING PULLS AWAY FROM THE REGION. THERE WILL STILL BE
ENHANCED AREAS OF SNOW SHOWER ACTIVITY…DUE TO UPSLOPE ACROSS THE
SOUTHERN GREENS…UPSLOPE/LAKE ENHANCEMENT ACROSS THE WESTERN
ADIRONDACKS…AND MULTI-BANDS OF LAKE EFFECT SNOW IN THE MOHAWK
VALLEY. WILL MENTION LIKELY POPS FOR THESE AREAS WITH JUST SLIGHT
CHANCE TO CHANCE ELSEWHERE THROUGH THE OVERNIGHT HOURS. A LAKE
EFFECT SNOW ADVISORY HAS BEEN ISSUED FOR SOUTHERN HERKIMER COUNTY.

IT WILL BECOME MUCH COLDER WITH INCREASING WINDS AFTER MIDNIGHT. ANY
WET AREAS OR PONDING WILL FREEZE AS TEMPERATURES DROP IN THE TEENS
AND 20S AREA WIDE.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/…
THANKSGIVING WILL BE A COLD AND BLUSTERY DAY ACROSS THE
REGION…WITH A CYCLONIC NORTHWESTERLY FLOW REGIME BECOMING FIRMLY
ESTABLISHED. MUCH OF THE AREA WILL JUST EXPERIENCE COLD AND DRY
CONDITIONS…HOWEVER DUE TO COLD AIR MOVING OVER THE RELATIVELY WARM
WATERS OF LAKE ONTARIO…LAKE EFFECT SNOW SHOWERS WILL CONTINUE
ACROSS PORTIONS OF THE WESTERN/CENTRAL MOHAWK VALLEY. WITH GENERALLY
A 295-300 DEGREE MIXED LAYER TRAJECTORY EXPECTED THROUGH MUCH OF
THANKSGIVING DAY AND NIGHT…OCCASIONAL MULTI-BANDS WILL IMPACT
THE MOHAWK VALLEY. THE BEST CHANCE FOR ADVISORY LEVEL ACCUMULATIONS
WILL CONTINUE TO BE ACROSS SOUTHERN HERKIMER COUNTY…WHERE LOCALLY
4-6 INCHES WILL BE POSSIBLE. FROM CENTRAL HERKIMER SOUTHEASTWARD
THROUGH FULTON AND MONTGOMERY COUNTIES…1-3 INCHES ARE POSSIBLE IN
OCCASIONAL SNOW SHOWERS. WILL ALSO MENTION SOME LIGHTER AMOUNTS UP
TO AN INCH DURING THE DAY FOR THE WESTERN ADIRONDACKS AND SOUTHERN
GREENS DUE TO UPSLOPE ENHANCEMENT. DRIER AIR MOVING IN LATER IN THE
DAY SHOULD RESULT IN A DECREASE IN SNOW SHOWER ACTIVITY OUTSIDE OF
THE LAKE EFFECT…WHICH WILL CONTINUE INTO THANKSGIVING NIGHT.

WITH A FAIRLY STRONG PRESSURE GRADIENT STILL OVER THE AREA…WINDS
ARE EXPECTED TO GUST BETWEEN 25 AND 35 MPH WITH THE HIGHER GUSTS
ACROSS WESTERLY FACING HIGHER TERRAIN LOCATIONS AS WELL AS AREAS
FAVORABLE FOR CHANNELING SUCH AS THE MOHAWK VALLEY AND CAPITAL
REGION. THE WIND WILL MAKE IT FEEL EVEN COLDER…WITH HIGH
TEMPERATURES ONLY EXPECTED TO REACH THE MID 20S TO AROUND 30 IN THE
VALLEYS AND UPPER TEENS TO LOWER 20S ACROSS THE HIGHER ELEVATIONS.
WINDS WILL START TO DECREASE THANKSGIVING NIGHT…BUT TEMPERATURES
WILL BE VERY COLD WITH TEENS IN MOST LOCATIONS EXCEPT SINGLE DIGITS
IN THE ADIRONDACKS.

GENERALLY DRY CONDITIONS ARE EXPECTED BY FRIDAY…AS HIGH PRESSURE
STARTS TO BUILD IN FROM THE GREAT LAKES. HOWEVER…SOME LEFT OVER
LIGHT LAKE EFFECT SNOW SHOWERS ARE POSSIBLE FOR WESTERN AREAS. IT
WILL REMAIN COLD…WITH TEMPERATURES RUNNING ABOUT 10-12 DEGREE
BELOW NORMAL. WIND SPEEDS WILL BE MUCH LIGHTER THOUGH MAKING IT
FEEL NOT AS COLD.

A STRONG 1040 MB HIGH PRESSURE SYSTEM WILL BUILD IN FOR FRIDAY NIGHT
INTO EARLY SATURDAY…SETTING THE STAGE FOR A VERY COLD NIGHT. NORTH
OF THE MOHAWK VALLEY AND CAPITAL REGION SINGLE DIGITS TO BELOW ZERO
READINGS ARE EXPECTED…WITH ONLY 10-15 SOUTH. WINDS SHOULD BE
MAINLY LIGHT THOUGH. COLD WEATHER TO PERSIST ON SATURDAY WITH
INCREASING CLOUDS AS THE HIGH SHIFTS EASTWARD INTO NEW ENGLAND.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/…
THE PERIOD WILL START OFF MAINLY DRY…WITH THE POSSIBLE EXCEPTION
OF SUNDAY AS A WEAK SHORTWAVE BRINGS A WEAK COLD FRONT THROUGH THE
REGION FROM THE NORTHWEST. A WEAK COASTAL AREA OF LOW PRESSURE
GETTING ITSELF TOGETHER OFF CAPE HATTERAS EARLY IN THE PERIOD WILL
SPREAD MOISTURE FAR ENOUGH NORTH TO CONSIDER A CHANCE OF SNOW MONDAY
NIGHT INTO TUESDAY…WITH THE HIGHER POPS FAVORED ACROSS THE
SOUTHERN ZONES. THEN…A HIGH PRESSURE RIDGE WILL BUILD ACROSS THE
AREA…STRETCHING FROM NORTHERN QUEBEC TO THE SOUTHEAST COAST ON
WEDNESDAY.

HIGH TEMPERATURES SUNDAY THROUGH TUESDAY WILL RANGE FROM AROUND 30
DEGREES IN THE ADIRONDACKS…TO THE LOWER 40S IN THE MID HUDSON
VALLEY…THE UPPER 20S TO AROUND 40 DEGREES ON WEDNESDAY. LOWS WILL
BE MOSTLY IN THE 20S TO AROUND 30 DEGREES WITH A FEW MINOR
EXCEPTIONS…BUT OVERALL…TUESDAY NIGHT WILL BE EVER SO SLIGHTLY
THE COLDEST OF THE NIGHTS. NORMAL HIGHS IN ALBANY IN EARLY DECEMBER
ARE AROUND 40 DEGREES…NORMAL LOWS…IN THE MID TO UPPER 20S.

&&

.AVIATION /22Z WEDNESDAY THROUGH MONDAY/…
SFC COASTAL LOW WILL MOVE NE ALONG I-95 CORRIDOR THIS AFTN AN
EVNG THRU NEW ENG AS 500HPA TROF MOVES ACROSS RGN. FCA IN CAA
WHICH WILL INCR DURING THE AFTN AND EVNG. HVY RAIN HAS EXITED TAF
SITES WITH ONLY -RN & -DZ OVER FCA ATTM. CIGS WILL BE MVFR REST OF
THE AFTN. A 500HPA SHORT WV WILL PROPAGATE NE AHEAD OF THE MAIN
TROF…CAUSING LT STEADIER PCPN TO BACK BUILD INTO FCST POINTS.
THIS WILL MAINTAIN MVFR TO OCNL IFR CONDS INTO THE EVNG. PTYPE
SHOULD TRANSITION TO SHSN 20-22UTC AT TAF SITES. NW WINDS WILL
INCR TO 10-20 KTS DURING THE AFTN.

TNGT THE TROF WILL MOVE E OF RGN AS 17MB WIND GRAD SETS UP ACROSS
NYS. NW WINDS WILL BE 15-25KTS. CIGS WILL BE MVFR TO VFR…BCMG VFR
CONDS LATE TNGT.

OUTLOOK…
THURSDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
FRIDAY TO SATURDAY: NO OPERATIONAL IMPACT. NO SIG WX.
SATURDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
SUNDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA…SHSN.
SUNDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
MONDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA…SHSN.

&&

.HYDROLOGY…
WILL ALLOW THE FLOOD WATCH TO CONTINUE UNTIL 6 PM FOR THE TACONICS
AND WESTERN NEW ENGLAND. RIVER LEVELS STILL RISING…WITH STILL SOME
POTENTIAL FOR MINOR FLOODING IN THE FLOOD WATCH AREA. WATCHING A FEW
POINTS THAT WILL GET CLOSE TO MINOR FLOOD STAGE. WILL HAVE A BETTER
IDEA BY 6 PM WHETHER TO EXTEND THE FLOOD WATCH OR CANCEL.

RAIN WILL TRANSITION TO SNOW THIS EVENING…WHICH WILL EVENTUALLY
SLOW RUNOFF ACROSS THE EASTERN HALF OF THE AREA. WITH NEAR OR BELOW
FREEZING TEMPERATURES ALREADY IN PLACE ACROSS WESTERN AREAS…RUNOFF
HAS ALREADY SLOWED.

PRECIPITATION CONTINUES TO RESULT IN SIGNIFICANT WITHIN BANK RISES
AND SOME PONDING OF SOME ROADWAYS WHERE LEFTOVER LEAVES COULD CLOG
STORM DRAINS. THE GOOD NEWS IS THAT FLOWS ARE RUNNING A BIT BELOW
NORMAL DUE TO PERSISTENT DRY WEATHER OF LATE.

MAINLY DRY WEATHER IS ANTICIPATED WITH BELOW NORMAL TEMPERATURES FOR
MUCH OF THE THANKSGIVING DAY HOLIDAY WEEKEND. ANY PRECIP WILL BE IN
THE FORM OF SNOW SHOWERS. RIVER FLOWS SHOULD QUICKLY LOWER IN THE
COLDER TEMPS. SOME LAKE EFFECT SNOW SHOWERS ARE EXPECTED WEST OF THE
CAPITAL REGION THROUGH THANKSGIVING NIGHT.

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…FLOOD WATCH UNTIL 6 PM EST THIS EVENING FOR CTZ001-013.
NY…FLOOD WATCH UNTIL 6 PM EST THIS EVENING FOR NYZ054-061-066.
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST FRIDAY FOR NYZ038.
MA…FLOOD WATCH UNTIL 6 PM EST THIS EVENING FOR MAZ001-025.
VT…FLOOD WATCH UNTIL 6 PM EST THIS EVENING FOR VTZ013>015.

&&

$$
SYNOPSIS…JPV
NEAR TERM…IAA/JPV
SHORT TERM…JPV
LONG TERM…ELH
AVIATION…SNYDER
HYDROLOGY…JPV

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