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Area Forecast Discussion
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000
FXUS61 KOKX 251905
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
205 PM EST TUE NOV 25 2014

.SYNOPSIS...
WEAK HIGH PRESSURE BUILDS IN BEHIND A DEPARTING COLD FRONT TODAY. 
LOW PRESSURE THEN DEEPENS AND TRACKS NORTHEAST TONIGHT. IT PASSES 
SOUTHEAST OF LONG ISLAND WEDNESDAY NIGHT...THEN HEADS INTO THE 
CANADIAN MARITIMES THURSDAY. HIGH PRESSURE THEN BUILDS IN BEHIND THE 
DEPARTING LOW FOR THE END OF THE WEEK. A WARM FRONT WILL LIFT
THROUGH ON SATURDAY....FOLLOWED BY A COLD FRONT SUNDAY NIGHT.
ANOTHER AREA OF HIGH PRESSURE BUILDS FROM THE NORTH FOR EARLY NEXT
WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CANOPY OF MID AND UPPER LEVEL CLOUDS STREAMING UP THE EASTERN
SEABOARD HAVE BEEN THICKER THAN ADVERTISED AND WILL GO WITH MOSTLY
CLOUDY SKIES. TEMPS HAVE PEAKED AND ACTUALLY HAVE DROPPED OFF A
FEW DEGREES IN SPOTS WITH THE COLD ADVECTION BEHIND THE COLD
FRONTAL PASSAGE EARLIER.

FULL LATITUDE UPPER TROF WILL PIVOT INTO THE MS VALLEY WITH
COASTAL CYCLOGENESIS TO ENSUE ALONG THE SE COAST BY THIS EVE. THIS
LOW WILL IMPACT THE AREA ON WED WITH A POTENTIAL HEAVY WET
SNOWFALL FOR PARTS OF THE TRI-STATE AREA.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
SOME WINTER STORM WATCHES HAVE BEEN UPGRADED TO WARNINGS ACROSS
THE INTERIOR. BASED ON 12Z GUIDANCE...CONFIDENCE OF A WARNING
LEVEL SNOW IN THOSE AREAS HAS INCREASED. REFER TO NYCWSWOKX OR
VISIT WEATHER.GOV/NYC FOR THE UPDATE. IT LOOKS TO BE A REAL CLOSE
CALL FOR THOSE LOCATIONS NEAR THE COAST WHERE THERMO PROFILES SHOW
AN ELEVATED WARM LAYER IN THE MID LEVELS WITH A NEARLY ISOTHERMAL
SOUNDING BELOW THAT. UNDOUBTEDLY ONE OF THE MORE CHALLENGING
FORECASTS AND CLEARLY AGAINST CLIMO.

MODEL CONSENSUS SHOWS A COASTAL LOW DEVELOPING OFF THE SOUTHEAST 
COAST TONIGHT. THE CENTER OF THIS STORM TRACKS NE THROUGH WEDNESDAY 
AND PASSES OVER OR VERY CLOSE TO THE 40N/70W BENCHMARK WEDNESDAY 
EVENING. BY LATE WEDNESDAY NIGHT...IT WILL BE CLOSE TO NOVA SCOTIA.

PRECIPITATION MOVES IN FROM THE SOUTH LATE AT NIGHT...WITH A
CHANCE THAT LONG ISLAND...THE CITY AND IMMEDIATE SURROUNDING
SUBURBS SEE SOME OF THIS PRECIPITATION BY DAYBREAK WEDS.
PRECIPITATION THEN STARTS BY NOON FOR THE ENTIRE TRI STATE AREA
AND PROBABLY ENDS BY DAYBREAK THURS FOR MOST OF THE AREA.

PRECIPITATION TYPE...AND CONSEQUENTLY THE SNOWFALL AMOUNT
FORECAST...WILL BE CHALLENGING. WITH A LACK OF A POLAR HIGH TO THE
NORTH...THE AMOUNT OF DYNAMIC COOLING BECOMES
IMPORTANT...PARTICULARLY ACROSS THE COASTAL ZONES. A LACK OF
DOWNSTREAM BLOCKING WILL HAVE THIS STORM TRACK RELATIVELY QUICKLY.

BASED ON WHERE MID LEVEL FRONTOGENESIS/TOTAL DEFORMATION AXES ALIGN 
WITH THE TIGHTEST 700MB TEMPERATURE GRADIENT...THE POTENTIAL FOR 
BANDED PRECIPITATION AND DYNAMIC COOLING OF THE THERMAL PROFILE
APPEARS TO BE ENHANCED OVER THE CITY...SOUTHWESTERN CT AND
BORDERING AREAS...COINCIDENT WITH OMEGA VALUES OF 20-30 MICROBARS
PER SECOND DURING THE LATER MORNING/AFTERNOON HOURS. THE OMEGA IS
NOT MAXIMIZED IN THE DENDRITIC SNOW GROWTH ZONES...BUT DOES
STRETCH INTO IT.

COMPLICATING THE PRECIPITATION TYPE FORECAST...MAINLY FOR EASTERN
CT AND EASTERN LI IS THE POTENTIAL OF AN ELEVATED WARM LAYER NEAR
700MB DURING THE AFTERNOON HOURS. ANYTHING THAT OTHERWISE WOULD
HAVE FALLEN AS SNOW COULD INSTEAD FALL AS SLEET...BUT NOT ENOUGH
CONFIDENCE YET TO INCLUDE SLEET IN THE FCST. MARGINAL
SURFACE/BOUNDARY LAYER TEMPERATURES WILL ALSO BE A FACTOR FOR
COASTAL AREAS.

ALL THINGS TAKEN INTO CONSIDERATION...WILL NOT CONVERT ANY OF THE 
WINTER STORM WATCHES TO WARNINGS JUST YET. WARNING CRITERIA MIGHT 
NOT BE FIRST MET UNTIL SOMETIME LATE IN THE 3RD PERIOD...AND FOR 
SOME AREAS...NOT UNTIL THE 4TH PERIOD. THERE IS SOME CONCERN THAT
QPF COULD LEAN TOWARDS THE DRIER 00Z GFS...WHICH WOULD TRANSLATE TO 
MARGINAL WARNING CRITERIA ACROSS THE LOWER HUDSON VALLEY AND 
ADJACENT AREAS. 00Z ECMWF HAS TRENDED A QUARTER INCH DRIER ON 
AVERAGE FROM THE PREVIOUS RUN. WILL HOWEVER EXPAND THE WINTER STORM 
WATCH A LITTLE SOUTHEAST TO COVER SW COASTAL CT...THE CITY...AND 
BORDERING AREAS. THIS IS TO ACCOUNT FOR THE AFOREMENTIONED
POTENTIAL OF MESOSCALE BANDING AND BETTER DYNAMIC COOLING.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
THE H5 FLOW ACROSS THE CONUS WILL BE UNDERGOING A CHANGE DURING THE 
LONG TERM PERIOD ALL CONTROLLED BY THE VORTEX SPINNING JUST N OF 
HUDSON BAY. UPPER TROUGH OVER THE ERN US WILL SHIFT OFFSHORE THU 
NIGHT/FRI AS THE RIDGE OVER THE WESTERN STATES FLATTENS AS IT MOVES 
EWD. ZONAL FLOW DEVELOPS OVER MUCH OF THE COUNTRY THIS WEEKEND WITH 
AMPLIFICATION BEGINNING EARLY NEXT WEEK AS A DEEP TROUGH/CUTOFF LOW 
APPROACHES THE WEST COAST.

NOT TOO MUCH TO BE CONCERNED WITH IN TERMS OF SENSIBLE WEATHER 
LOCALLY...ALTHOUGH WINTER-LIKE TEMPERATURES WILL RETURN THU AND FRI 
WITH HIGHS/LOWS BETWEEN 10 AND 15 DEGREES BELOW NORMAL THANKS TO THE 
AFOREMENTIONED UPPER TROUGH.

COULD SEE SOME SOUND EFFECT SNOW/RAIN SHOWERS OR FLURRIES ON A WLY 
FLOW...MAINLY ON LI...THU AS ENERGY ASSOCIATED WITH THE UPPER TROUGH 
AXIS SWINGS THROUGH. GFS IS THE MOST ROBUST WITH QPF WHILE OTHER 
MODELS ARE DRY SO HAVE ONLY GONE SCHC POPS FOR NOW.

DRY WEATHER THEN PREVAILS AS SFC HIGH BUILDS ACROSS THE AREA THU 
NIGHT/FRI. A WARM FRONT LIFTS THROUGH ON SAT...BUT HAVE KEPT 
FORECAST DRY WITH LIMITED MOISTURE. WE'LL REMAIN WARM SECTORED INTO 
SUN WITH WAA ENSUING. WARMER BUT STILL BELOW NORMAL TEMPS AS A COLD 
FRONT APPROACHES. THE FRONT WILL TRACK ACROSS THE AREA SUN 
NIGHT...BUT AGAIN LOOKS TOO DRY FOR ANY PRECIPITATION. THE
FORECAST EARLY NEXT WEEK BECOMES FUZZY DUE TO THE TIMING OF THE
NEXT AREA OF HIGH PRES BUILDING FROM THE N. THE DETERMINISTIC
GFS/EC MODELS ARE SLOWER TO BUILD THE HIGH IN AND KEEP THE FRONTAL
BOUNDARY NEARBY WITH A WAVE OF LOW PRES DEVELOPING ALONG IT AND
TRACKING OVER THE AREA ON MON. THE ENSEMBLES BUILD THE HIGH IN
QUICKER...SUPPRESSING THE FRONT TO THE S WITH DRY WEATHER
CONTINUING.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
***HIGH IMPACT WINTER WEATHER EVENT WEDNESDAY INTO WEDNESDAY NIGHT***

WEAK HIGH PRESSURE WILL NOSE IN THIS AFTERNOON AND EVENING.
DEVELOPING LOW PRESSURE WILL THEN MOVE ALONG THE SOUTHEAST COAST
OVERNIGHT...AND THEN PASS OFF THE MID ATLANTIC COAST WED MORNING. 

WINDS...W TO WNW WINDS 10-15 KT WITH OCNL GUSTS 15-20 KT SHOULD
START TO DIMINISH BY 20Z. WINDS TONIGHT WILL THEN GRADUALLY VEER
NW TO NW AT SPEEDS GENERALLY 5-8 KT...EXCEPT UNDER 5 KT INLAND.
N-NE WINDS INCREASE TO 10-15 KT AFTER DAYBREAK...WITH GUSTS 15-20
KT TOWARD MIDDAY WED. 

FLIGHT CAT AND PRECIP...VFR MOST OF TONIGHT. PRECIP SHOULD MOVE IN
LATE TONIGHT WITH CIGS DROPPING QUICKLY TO MVFR. EXCEPT FOR
KSWF WHICH SHOULD BE ALL SNOW...TIMING/DEGREE OF COOLING DURING
THE MORNING AND OF COURSE CHANGE IN PRECIP TYPE ALL UNCERTAIN... 
AT THE NYC METROS THINK A MIX WITH SNOW COULD TAKE PLACE AS EARLY
AS 15Z WITH A CHANGE TO WET SNOW BY 17Z. EXPECT THIS TO TAKE PLACE
ABOUT AN HR SOONER AT KHPN/KBDR. KISP LIKELY TO REMAIN ALL RAIN
FOR MOST OF THE MORNING. REGARDLESS OF PRECIP TYPE...IFR CONDS
LIKELY TO DEVELOP DURING THE LATE MORNING...BY 13Z AT KSWF AND
ABOUT 15Z ELSEWHERE. 

...NY METRO ENHANCED AVIATION WEATHER SUPPORT...

DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT:  HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)

KJFK FCSTER COMMENTS: TIMING OF PRECIP CHANGES WED MORNING COULD
OCCUR A COUPLE OF HRS LATER THAN FCST. 

KLGA FCSTER COMMENTS: TIMING OF PRECIP CHANGES WED MORNING COULD
OCCUR A COUPLE OF HRS LATER THAN FCST. 

KEWR FCSTER COMMENTS: TIMING OF PRECIP CHANGES WED MORNING COULD
OCCUR A COUPLE OF HRS LATER THAN FCST. 

KTEB FCSTER COMMENTS: TIMING OF PRECIP CHANGES WED MORNING COULD
OCCUR A COUPLE OF HRS LATER THAN FCST. 

KHPN FCSTER COMMENTS: TIMING OF PRECIP CHANGES WED MORNING COULD
OCCUR A COUPLE OF HRS LATER THAN FCST. 

KISP FCSTER COMMENTS: TIMING OF PRECIP CHANGES WED MORNING COULD
OCCUR A COUPLE OF HRS LATER THAN FCST. 

.OUTLOOK FOR 18Z WED THROUGH SAT...

.WED AFTERNOON/WED NIGHT...IFR/LIFR CONDS...WITH PRECIP CHANGING
TO ALL SNOW BUT STAYING RAIN OR A RAIN/SNOW MIX AT KISP/KGON IN
THE AFTERNOON...THEN CHANGING TO ALL SNOW THROUGHOUT EARLY IN THE
EVENING. PRECIP SHOULD TAPER OFF FROM LATE EVENING INTO THE
OVERNIGHT...WITH CONDS IMPROVING TO MVFR. MOST LIKELY RUNWAY
ACCUMULATIONS 3-6 INCHES NYC METRO TERMINALS... 8-11 INCHES
KSWF/KHPN...2-4 INCHES KBDR...1-2 INCHES KISP/KGON. N WINDS
12-18G20-25KT IN THE AFTERNOON AND EVENING...BECOMING NW AND
DIMINISHING AFTER MIDNIGHT.

.THU-THU NIGHT...LINGERING SNOW SHOWERS POSSIBLE IN THE MORNING
WITH MVFR CONDS...THEN VFR. 

.FRI-SUNDAY...VFR. 

&&

.MARINE...
SCA WILL CONTINUE ON THE OCEAN AS SEAS WILL BE SLOW TO SUBSIDE
BELOW 5 FT. HAVE EXTENDED THIS SAC TO GO INTO THIS EVENING...AND
MAY NEED TO EVENTUALLY BE EXTENDED IN TIME EAST OF FIRE ISLAND
INLET.

A COASTAL LOW BRINGS THE LIKELIHOOD OF GALE CONDITIONS TO THE 
COASTAL OCEAN WATERS WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT. THE 
GALE WATCH ON THE OCEAN HAS BEEN CONVERTED TO A WARNING. SOME/ALL OF 
THE NON-OCEAN WATERS MAY NEED A SMALL CRAFT ADVISORY FOR ROUGHLY THE 
SAME PERIOD. WILL ALLOW DAY SHIFT TO FINE TUNE THE FORECAST BEFORE 
ISSUING ANY FLAGS CONCERNING THIS.

SAC SEAS WILL LIKELY CONTINUE ON THE OCEAN WATERS THURS THROUGH
THU NIGHT. THE PRES GRADIENT WILL INCREASE THU NIGHT AS WELL SO
MARGINAL NW SAC WIND GUSTS/SEAS CONTINUING INTO FRI REMAIN
POSSIBLE ON THE OCEAN WATERS. TRANQUIL CONDITIONS THEN EXPECTED
ON ALL WATERS AS HIGH PRES BUILDS OVER AND EAST OF THE WATERS
THROUGH SAT. MARGINAL SAC CONDS ARE THEN AGAIN POSSIBLE SAT NIGHT
WITH THE GRADIENT INCREASING BETWEEN THE DEPARTING HIGH AND LOW
PRESSURE PASSING TO THE NORTH.

&&

.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION THROUGH MOST OF TONIGHT.

FOR WEDS AND WEDS NIGHT...EXPECTING A LIQUID  EQUIVALENT
PRECIPITATION AMOUNTS AVERAGING AROUND 0.75 TO 1.5. THE HIGHEST
QPF AMOUNTS AREA CURRENTLY EXPECTED OVER EASTERN CT/LONG ISLAND
AND THE LOWEST OVER FAR WESTERN PORTIONS OF THE TRI-STATE.

OVER THE INTERIOR MOST OF THIS WILL FALL IN THE FORM OF SNOW...SO 
LITTLE IF ANY IMMEDIATE HYDROLOGIC IMPACT IS EXPECTED THERE. FARTHER 
TO THE S/E...BASICALLY ALONG AND E OF I-95...THERE WILL BE A A MIX 
OF RAIN AND SNOW. THIS COULD CAUSE MINOR FLOODING OF URBAN/POOR 
DRAINAGE AREAS.

THEREAFTER...VERY LIGHT QPF AMOUNTS ARE POSSIBLE THROUGH THE WEEKEND.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 7 AM EST THURSDAY 
     FOR CTZ005-006.
     WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY 
     MORNING FOR CTZ007>010.
NY...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 7 AM EST THURSDAY 
     FOR NYZ067>070.
     WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY 
     MORNING FOR NYZ071>075-176>178.
NJ...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 7 AM EST THURSDAY 
     FOR NJZ002-103.
     WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY 
     MORNING FOR NJZ004-006-104>108.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM WEDNESDAY TO 1 AM EST THURSDAY 
     FOR ANZ330-335-338-340-345.
     SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR ANZ350-353-
     355.
     GALE WARNING FROM 11 AM WEDNESDAY TO MIDNIGHT EST WEDNESDAY 
     NIGHT FOR ANZ350-353-355.

&&

$$
SYNOPSIS...JC/24
NEAR TERM...JC/24/DW
SHORT TERM...JC/DW
LONG TERM...24
AVIATION...GOODMAN
MARINE...JC/24
HYDROLOGY...JC/24






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