Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 291516
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
1116 AM EDT FRI MAY 29 2015

.SYNOPSIS...
HIGH PRESSURE WILL SET UP OVER THE ATLANTIC THROUGH SATURDAY. A
COLD FRONT APPROACHES SATURDAY NIGHT AND MOVES THROUGH THE REGION
ON SUNDAY. THE FRONT WILL STALL JUST SOUTH OF THE AREA AS WEAK
WAVES OF LOW PRESSURE RIDE ALONG IT. HIGH PRESSURE THEN BUILDS IN
FROM THE NORTH LATE TUESDAY INTO WEDNESDAY...SHIFTING SOUTH OF THE
AREA ON THURSDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
NO MAJOR CHANGES MADE WITH THE LATEST UPDATE. THE FORECAST IS ON
TRACK. HI PRES RIDGE DRIFTS THRU THE CWA TODAY AND OFFSHORE BY
EVE. NORTHERLY FLOW THIS MORNING WILL THEREFORE GRADUALLY VEER TO
THE S TODAY. WATER VAPOR SHOWS A VERY DRY AIRMASS BUILDING OVER
THE AREA...SO WILL FORECAST A MAINLY CLEAR SKY THRU TONIGHT. THE
RETURN FLOW HOWEVER WILL ALLOW FOR INCREASING HUMIDITY DUE TO THE
LOW LEVEL MOISTURE INFLUX...AND WITH THE DRY MID LEVELS SOME
PATCHY FOG WILL BE POSSIBLE TONIGHT.

TEMPS WERE CLOSE TO A BLEND OF GUIDANCE AS THE NUMBERS WERE IN
GOOD AGREEMENT. HOWEVER...THERE IS THE POTENTIAL FOR SOME LOCALLY
HIGHER TEMPS TODAY PARTICULARLY OVER LONG ISLAND IF THE OPPOSING
NORTHEASTERLY FLOW HOLDS THE SEA BREEZE BACK A BIT. THE NAMDNG
SUGGESTS NEAR 80 ALONG ROUGHLY THE 495 CORRIDOR. AS A RESULT
BUMPED UP HIGHS IN THIS AREA A FEW DEGREES.

&&

.SHORT TERM /SATURDAY/...
DESTABILIZATION BY AFTERNOON ACROSS WRN ZONES WITH SSW FLOW. THIS
WILL AGAIN KEEP ERN PORTIONS OF THE CWA...ESPECIALLY THE
COASTS...STABLE. THE NAM HINTS AT TEMPS REMAINING IN THE 60S
ACROSS THE S SHORE OF LONG ISLAND AND MUCH OF COASTAL CT.
ALTHOUGH THIS MAY BE A BIT MUCH...DID LOWER TEMPS IN THIS AREA AND
WILL BANK ON A STABLE AIRMASS. ACROSS THE W...THE MAIN QUESTION
WILL BE WHETHER THERE WILL BE A SUFFICIENT TRIGGER. THE JET WILL
BE TOO FAR UPSTREAM...BUT THE MODELS DO HINT AT SOME SUBTLE MID
LVL FORCING. MAINTAINED THE CURRENT CHANCE POPS FOR THE AFTERNOON
HOURS ACROSS APPROXIMATELY THE WRN 1/3 OF THE CWA.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
WESTERN ATLANTIC RIDGE WEAKENS SLIGHTLY AT THE START OF THE LONG
TERM PERIOD SATURDAY NIGHT WITH HEIGHTS BEGINNING TO FALL OVER THE
AREA. THIS WILL ALLOW A COLD FRONT TO APPROACH FROM THE NORTHWEST.
THE BEST CHANCES FOR SHOWERS AND THUNDERSTORMS WILL BE NORTH AND
WEST OF NEW YORK CITY EARLY SATURDAY NIGHT...AND THEN POPS INCREASE
FROM WEST TO EAST LATE SATURDAY NIGHT AS THE FRONT DRAWS CLOSER.

THE FRONT SHOULD BE ENTERING THE INTERIOR SUNDAY MORNING AND MOVING
SOUTH THROUGH THE REMAINDER OF THE AREA DURING THE LATE MORNING AND
EARLY AFTERNOON HOURS. MODELS GENERALLY AGREE ON THIS SCENARIO
ALTHOUGH IT IS POSSIBLE THE TIMING SLOWS DOWN IN LATER RUNS AS THE
MODELS CAN BE TOO FAST MOVING FRONTS SOUTH WITH DEEP RIDGING OFF THE
COAST. THE FRONT DOES HAVE A GOOD PUSH SOUTH HOWEVER WITH A NEAR
1030 MB HIGH OVER THE GREAT LAKES REGION AND A SHORTWAVE MOVING
ACROSS SOUTHEAST CANADA AND NORTHERN NEW ENGLAND.

POPS INCREASE TO LIKELY FROM NW TO SE ACROSS THE AREA SUNDAY MORNING
INTO THE AFTERNOON. WITH ABUNDANT CLOUD COVER AND
PRECIPITATION...INSTABILITY WILL LIKELY BE LOW. HAVE CONTINUED THE
WORDING FROM PREVIOUS FORECAST WITH SHOWERS LIKELY WITH A CHANCE OF
THUNDERSTORMS. A DEEP MOISTURE FEED AROUND THE RIDGE TAPPING INTO
THE GULF OF MEXICO BRINGS HIGH PRECIPITABLE WATERS RANGING FROM 1.5
TO 1.8 INCHES. LOCALLY HEAVY RAINFALL IS POSSIBLE WITH ANY SHOWERS
IN THIS AIRMASS.

SHOWERS CONTINUE SUNDAY NIGHT INTO MONDAY AS THE FRONT STALLS JUST
SOUTH OF THE AREA. WEAK WAVES OF LOW PRESSURE WILL RIDE ALONG THE
BOUNDARY. ALOFT...SOME SHORT WAVE ENERGY...AND THE REGION BEING
LOCATED NEAR THE RIGHT ENTRANCE REGION OF A 80-100 KT UPPER LEVEL
JET ACROSS NORTHERN NEW ENGLAND AND SOUTHEAST CANADA PROVIDE A
LARGER SCALE LIFTING MECHANISM. LOCALLY HEAVY RAINFALL REMAINS A
POSSIBILITY THROUGH AT LEAST MONDAY MORNING. POPS WILL SLOWLY TAPER
TO HIGH CHANCE IN THE AFTERNOON FOR NORTHERN ZONES...BUT REMAIN
LIKELY ACROSS THE SOUTH.

POPS CONTINUE TRENDING DOWNWARD MONDAY NIGHT INTO TUESDAY MORNING.
HOWEVER...MODELS DIFFER ON THE HANDLING OF A MORE WELL DEFINED SHORT
WAVE AT 500 MB LATE MONDAY NIGHT INTO TUESDAY. THE 00Z ECMWF IS
SLOWER AND INDICATES A MORE NEUTRAL TILT WHICH ALLOWS WIDESPREAD
SHOWER ACTIVITY TO CONTINUE WELL INTO TUESDAY. THE GFS AND CMC SHIFT
THE FRONT FURTHER SOUTH WITH A POSITIVELY TILTED SHORTWAVE QUICKER
TO MOVE THROUGH. WILL NEED TO SEE IF THE ECMWF IS ON TO SOMETHING AS
THE NEW 00Z RUN IS CONSISTENT WITH ITS PREVIOUS 12Z RUN. FOR
NOW...FORECAST SHOWS A LOW CHANCE POPS FOR SOUTHERN ZONES TUESDAY
MORNING BUT THESE MAY NEED TO BE INCREASED IF THE MODELS COME MORE
INTO LINE WITH THE ECMWF.

HIGH PRESSURE WILL BUILD INTO THE REGION TUESDAY NIGHT THROUGH
WEDNESDAY...AND THEN SHIFT SOUTH INTO THE WESTERN ATLANTIC ON
THURSDAY. THIS WILL ALLOW FOR DRIER CONDITIONS TO RETURN.

TEMPERATURES WILL BE NEAR NORMAL ON SUNDAY...AVERAGE BELOW NORMAL
MONDAY THROUGH WEDNESDAY...AND BE NEAR NORMAL ON THURSDAY.

&&

.AVIATION /11Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE WILL REMAIN OFFSHORE THIS AFTERNOON...THEN SLOWLY
RETREATS TO THE EAST TONIGHT.

VFR THROUGH THE TAF PERIOD.

WINDS BECOME SE AT 10 KT OR LESS BY ERLY AFT...THEN LIGHT AND
VARIABLE TONIGHT.

     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 CHANGES IN WIND SPEED/DIRECTION
COULD BE OFF +/- 2-3 HOURS.

KLGA FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION
COULD BE OFF +/- 2-3 HOURS.

KEWR FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION
COULD BE OFF +/- 2-3 HOURS.

THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH
IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.

KTEB FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION
COULD BE OFF +/- 2-3 HOURS.

KHPN FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION
COULD BE OFF +/- 2-3 HOURS.

KISP FCSTER COMMENTS: TIMING OF CHANGES IN WIND SPEED/DIRECTION
COULD BE OFF +/- 2-3 HOURS.

.OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY...
.SATURDAY MORNING...MVFR OR LOWER POSSIBLE.
.SATURDAY AFTERNOON...MOST LIKELY VFR. CHANCE OF MVFR IN
SHOWERS/THUNDERSTORMS MAINLY TO THE N/W OF CITY TERMINALS. GUSTS
TO 20-25KT POSSIBLE WITH SEABREEZE.
.SATURDAY NIGHT-TUESDAY MORNING...MVFR OR LOWER AT TIMES.
THUNDERSTORMS POSSIBLE SATURDAY NIGHT-SUNDAY NIGHT.
.TUESDAY AFTERNOON/NIGHT...BECOMING VFR.

&&

.MARINE...
HI PRES WILL KEEP WINDS AND SEAS BELOW SCA LEVELS THRU TONIGHT. S
FLOW INCREASES THRU THE DAY ON SAT WITH SCA CONDITIONS POSSIBLE
BY LATE AFTERNOON...ESPECIALLY THE OCEAN AND S SHORE BAYS.

SCA CONDITIONS ARE LIKELY ON THE OCEAN WATERS FROM SATURDAY NIGHT
THROUGH TUESDAY. A COLD FRONT WILL BE APPROACHING SATURDAY NIGHT
WITH STRONG SOUTHERLY FLOW AHEAD OF IT. SEAS ON THE OCEAN WILL BE
NEAR 5 FT AND WINDS COULD GUST UP TO 25 KT. THE FRONT CROSSES THE
WATERS ON SUNDAY WITH A STRENGTHENING NE FLOW BEHIND IT. SEAS LIKELY
BUILD UP TO 7 FEET ON MONDAY AND CONTINUE INTO TUESDAY ON THE
OCEAN.

&&

.HYDROLOGY...
THE POTENTIAL CONTINUES FOR AN EXTENDED SIGNIFICANT WIDESPREAD
RAINFALL...MAINLY SUNDAY THROUGH MONDAY WITH A COLD FRONT STALLING
NEAR THE REGION. IT IS DIFFICULT TO SPECIFY EXACT RAINFALL
AMOUNTS...BUT THERE WILL BE POTENTIAL FOR HEAVY RAINFALL ESPECIALLY
SUNDAY AND SUNDAY NIGHT INTO MONDAY MORNING WHEN PRECIPITABLE WATERS
REACH 1.5 TO 1.8 INCHES. ANY HEAVIER SHOWERS PRODUCE LOCALLY HEAVY
RAINFALL AND THEREFORE AT LEAST MINOR FLOODING OF URBAN/POOR
DRAINAGE AREAS WILL BE A POSSIBILITY. LOCALIZED FLASH FLOODING
CANNOT BE RULED OUT.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...JMC/DS
NEAR TERM...JMC/DS
SHORT TERM...JMC
LONG TERM...DS
AVIATION...MALOIT
MARINE...JMC/DS
HYDROLOGY...DS


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