Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 230303
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
1003 PM EST MON DEC 22 2014

.SYNOPSIS...
LOW PRESSURE OFF CAPE HATTERAS WILL DRIFT SLOWLY NORTH OFF THE
DELMARVA COAST TONIGHT...THEN PASS JUST SOUTHEAST OF LONG ISLAND
LATER TUESDAY INTO TUESDAY NIGHT. A MORE SIGNIFICANT STORM SYSTEM
WILL AFFECT THE AREA WEDNESDAY THROUGH CHRISTMAS MORNING...WITH A
COLD FRONT PASSING THROUGH DURING CHRISTMAS MORNING. HIGH PRESSURE
WILL BUILD IN FROM LATE THURSDAY THROUGH FRIDAY. A WEAK LOW
PRESSURE TROUGH WILL MOVE THROUGH ON SATURDAY. ANOTHER LOW WILL
APPROACH FROM THE SOUTH SATURDAY NIGHT INTO SUNDAY.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
TEMPS ACROSS ORANGE COUNTY IN THE MID 30S WITH DEWPOINTS IN THE
LWR TO MID 30S. NAM12 CONFIRMS WET BULB ZERO HGT A FEW HUNDRED FT
UP...SO DO NOT EXPECT SFC TEMPS TO WET BULB TO FREEZING TNGT. AS A
RESULT...HAVE CANCELLED THE FZRA ADVY.

OTHERWISE...RAIN AND DZ CONTINUES TO FLOW INTO THE REGION FROM THE
SW...SO HAVE ADJUSTED POPS ACCORDINGLY. KEPT VSBY TO AROUND 2SM IN
THE DZ BASED ON UPSTREAM OBS...BUT SOME OF THE HIGHER SPOTS COULD
GO LWR WITH ELY COMPONENT UPSLOPE.

LOWS TONIGHT WILL BE IN THE MID/UPPER 30S ELSEWHERE INLAND...AND
IN THE LOWER 40S IN NYC METRO AND ALONG THE COAST.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
THE LOW WILL WEAKEN AS IT SLIDES JUST TO THE SE OF LONG ISLAND ON
TUE. ITS OVERRUNNING PRECIP SHOULD ALSO PASS TO THE NE...LEAVING
CLOUDY SKIES AND STILL CHANCES FOR SOME LIGHT RAIN MOST OF THE
DAY TUE INTO TUE EVENING. LIKELY POP EXPECTED LATE TUE NIGHT AS
DEEP LAYER SW FLOW DEVELOPS AND ANOTHER WARM FRONT APPROACHES AND
REMAINS JUST TO THE SOUTH.

HIGHS TEMPS SHOULD BE NEAR 50 ACROSS NYC METRO AND LONG
ISLAND...AND IN THE MID/UPPER 40S ELSEWHERE...THEN DROPPING INTO
THE MID/UPPER 30S INLAND AND LOWER/MID 40S FOR NYC METRO AND
COASTAL SECTIONS TUE NIGHT AS A WARM FRONT REMAINS JUST TO
THE SOUTH.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
FORECAST FOR THE MOST PART REMAINS CONSISTENT PAST COUPLE
DAYS...ONLY CHANGE IS A LITTLE LATER COLD FRONTAL PASSAGE AND RAIN
LINGERING INTO CHRISTMAS MORNING ACROSS THE EASTERN ZONES AS UPPER
TROUGH BECOMES MORE NEGATIVE AND THE UPPER LOW CLOSES OFF WEDNESDAY
NIGHT. BOTH THE GFS AND ECMWF HANDLE THE SYSTEM WELL WITH THE NAM
NOT AS DEEP AND SLOWER THAN THE OTHER GUIDANCE. THE LOW LEVEL JET IS
ALSO A LITTLE WEAKER THAN DURING THE PAST FEW RUNS...NOW AROUND 50
KT. THE LOW LEVEL JET WILL STILL PROVIDE SIGNIFICANT LIFT WEDNESDAY
AFTERNOON AND EVENING FOR PERIODS OF HEAVY RAINFALL. THE AREA STILL
DOES NOT BECOME WARM SECTORED AS THE WARM FRONT REMAINS TO THE
SOUTH. SO WILL NOT BE MENTIONING ANY CONVECTION. STRONG COLD
ADVECTION SETS UP BEHIND THE COLD FRONT THURSDAY MORNING AND
CONTINUES INTO THE EVENING...WEAKENING 00Z TO 06Z FRIDAY. WIND AND
GUSTS REMAIN BELOW ADVISORY LEVELS THURSDAY.

HIGH PRESSURE BUILDS IN FRIDAY. AGAIN...CONSISTENCY REMAINS WITH THE
WEAKENING TROUGH AND DRY COLD FRONTAL PASSAGE SATURDAY. IN THE
SOUTHERN STREAM A WAVE DEVELOPS ON THE FRONTAL BOUNDARY AND TRACKS
NORTH SATURDAY NIGHT INTO SUNDAY. SOME DIFFERENCES IN GUIDANCE AS
THIS WAVE WILL BE COMING INTO THE PACIFIC NORTHWEST WEDNESDAY NIGHT
AND MAY NOT BE INITIALIZED WELL. SO FROM SATURDAY THROUGH MONDAY
GENERALLY FOLLOWED WPC GUIDANCE.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
WEAK LOW PRESSURE WILL TRACK SLOWLY NORTH FROM THE MID ATLANTIC
COAST TONIGHT TO JUST SOUTH OF LONG ISLAND ON TUE. THIS WILL PLACE
THE AREA IN AN EASTERLY FLOW WITH THE DEVELOPMENT OF WIDESPREAD
IFR CONDITIONS AND LIGHT RAIN AND/OR DRIZZLE.

PCPN WILL BECOME MORE WIDESPREAD OVERNIGHT AS BANDS OF LIGHT RAIN
ASSOCIATED WITH THE WEAK LOW CONTINUE TO FEED IN FROM THE S.
RAIN IS EXPECTED TO CONTINUE THROUGH TUE MORNING AS THE LOW TRACKS
TO THE NJ COAST AND THEN WEAKENS AS IT MOVES NE DURING THE AFTN. THERE
IS THE POSSIBILITY OF A LULL DURING TUE AFTN WITH JUST DRIZZLE
ALTHOUGH SATURATION IN THE LOW LEVELS COULD BE DEEP ENOUGH FOR LIGHT
RAIN TO CONTINUE. A WARM FRONT APPROACHES TUE NIGHT WITH STEADY RAIN
RETURNING.

NE-E WINDS 5 TO 10 KT...STRONGEST NEAR THE COAST WHERE THEY COULD
GET UP TO 10-15 KT TONIGHT. WIND DIRECTIONS UNCERTAIN AFT 16Z TUE WHICH
WILL DEPEND ON LOCATION AND TRACK OF WEAK LOW S OF LONG ISLAND.

.OUTLOOK FOR 00Z TUESDAY THROUGH SATURDAY...
.TUE NIGHT...IFR LIKELY. RAIN REDEVELOPING.
.WED-WED NIGHT...HIGH IMPACT EVENT LIKELY. IFR WITH OCNL +RA.
S/SE WINDS 15-20G20-25KT POSSIBLE. LLWS PROBABLE SOUTHERN AND
EASTERN TERMINALS. WINDS SHIFT TO THE SW LATE AT NIGHT.
.THU-THU NIGHT...IMPROVING TO VFR IN THE MORNING FROM W TO E.
WSW-NW WINDS G30-35+KT LIKELY.
.FRI...VFR. WNW WINDS G20-25KT POSSIBLE.
.SAT...VFR. SW WINDS G20 KT.

&&

.MARINE...
SCA NOW IN EFFECT FOR ALL THE OCEAN WATERS AS THE PRESSURE
GRADIENT TIGHTEN BETWEEN DEPARTING HIGH PRESSURE AND A WEAK LOW
DRIFTING UP FROM THE SOUTH...BUT WITH DIFFERING TIMING.
MARGINAL SCA CONDS EXPECTED E OF MORICHES INLET INITIALLY...THEN
GRADUALLY SPREADING WESTWARD TO ALL THE OCEAN WATERS BY LATER
TONIGHT. AS THE LOW PASSES CLOSE BY ON TUE...WINDS AND SEAS
SHOULD SUBSIDE...WITH ONLY LINGERING 5-FT SEAS E OF MORICHES
THROUGH THE DAY ON TUE....AND POSSIBLY INTO EARLY TUE EVENING.

AN INCREASING SE TO S FLOW AHEAD OF AN APPROACHING COLD FRONT
WILL ALLOW FOR SEAS TO BUILD ON THE OCEAN WATERS WED INTO WED
NIGHT. IN ADDITION...SOME GUSTS ACROSS THE FORECAST OCEAN WATERS
MAY INCREASE TO SMALL CRAFT LEVELS WEDNESDAY NIGHT. A COLD FRONT
CROSSES THE WATERS FROM AROUND 12Z TO 18Z THURSDAY. THE SOUTHERLY
WIND SHIFTS TO THE WEST TO NORTHWEST IN THE COLDER AIR. WIND GUSTS
WILL CONTINUE TO INCREASE AND LIKELY REACH GALE FORCE LEVELS
ACROSS ALL THE FORECAST WATERS BY MIDDAY THURSDAY. THEN AS HIGH
PRESSURE BUILDS IN FROM THE SOUTH AND COLD ADVECTION WEAKENS WIND
AND GUSTS WILL DIMINISH THURSDAY EVENING INTO LATE THURSDAY
NIGHT...FALLING BELOW EVEN SMALL CRAFT LEVELS BY FRIDAY MORNING.

THE THE WESTERLY FLOW THURSDAY INTO FRIDAY SEAS ON THE OCEAN WATERS
WILL BE SLOWLY SUBSIDING...FALLING BELOW 5 FT BY LATE FRIDAY.

AS HIGH PRESSURE WEAKENS FRIDAY NIGHT AND A TROUGH APPROACHES
SATURDAY...SOUTHWESTERLY WIND WILL INCREASE. GUSTS ARE EXPECTED TO
REMAIN BELOW 25 KT...HOWEVER SEAS ON THE OCEAN WATERS WILL LIKELY
BUILD BACK UP TO SMALL CRAFT LEVELS LATE FRIDAY NIGHT INTO SATURDAY.
THEN SUBSIDE ONCE AGAIN SUNDAY AS LOW PRESSURE MOVES INTO THE WATERS
AND THE PRESSURE GRADIENT WEAKENS.

&&

.HYDROLOGY...
BASIN AVG RAINFALL OF 1/2 TO 3/4 INCH EXPECTED THROUGH TUE
NIGHT...THEN ANOTHER 1 TO 1 1/2 INCHES WITH LOCALLY HIGHER AMTS
EXPECTED WED INTO THU MORNING...WITH TOTAL RAINFALL OF 1 1/2 TO 2
INCHES WITH LOCALLY HIGHER AMOUNTS. MINOR URBAN AND POOR
DRAINAGE FLOODING IS POSSIBLE.

UP TO AN INCH OF LIQUID EQUIVALENT QPF POSSIBLE SAT NIGHT INTO
SUNDAY NIGHT.

&&

.TIDES/COASTAL FLOODING...
STORM SURGE A LITTLE OVER 1 FT EXPECTED VIA A STRENGTHENING E
FLOW BETWEEN DEPARTING HIGH PRESSURE AND A WEAK LOW DRIFTING UP
FROM THE SOUTH. THIS COULD BRING WATER LEVELS CLOSE TO OR JUST
OVER MINOR COASTAL FLOOD THRESHOLDS WITH THE HIGH TIDE CYCLE
DURING MID TO LATE TUE MORNING...ON THE WESTERN SOUND...THE SOUTH
SHORE BAYS OF WESTERN LONG ISLAND...AND POSSIBLY IN PECONIC BAY.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST TUESDAY FOR ANZ355.
     SMALL CRAFT ADVISORY UNTIL 6 PM EST TUESDAY FOR ANZ350.
     SMALL CRAFT ADVISORY UNTIL 6 AM EST TUESDAY FOR ANZ353.

&&

$$



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