Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 011947
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
347 PM EDT MON SEP 1 2014

.SYNOPSIS...
WEAK HIGH PRESSURE REMAINS OVER THE REGION TONIGHT IN THE WAKE OF A
SURFACE TROUGH. A COLD FRONT THEN APPROACHES DURING TUESDAY BEFORE
PASSING THROUGH TUESDAY NIGHT. HIGH PRESSURE BUILDS IN FOR THE LATTER
HALF OF THE WEEK. ANOTHER COLD FRONT WILL IMPACT THE REGION THIS
WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
ISO/SCT CONVECTION DIMINISHES THIS EVENING FROM THE COMBINATION OF
ATMOSPHERIC STABILIZATION...LOSS OF MOISTURE CONVERGENCE DUE TO A
DEPARTING/DISSIPATING SURFACE TROUGH...AND UPPER LIFT SHIFTING EAST
OUT OF THE AREA. PWAT VALUES WILL STILL BE ON THE HIGH SIDE...SO
HEAVY DOWNPOURS REMAIN POSSIBLE IN ANY SHOWERS/TSTMS.

DRY WEATHER BY AROUND MIDNIGHT...BUT REMAINING MUGGY AS DEWPOINTS
HOVER AROUND 70. PATCHY LIGHT FOG PROBABLY DEVELOPS OVERNIGHT AS
WELL.

THERE IS A MODERATE RISK OF RIP CURRENTS INTO THIS EVENING.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
COLD FRONT APPROACHES DURING THE DAY TUESDAY. A PRE-FRONTAL TROUGH
AHEAD OF IT DEVELOPS NEAR OUR WESTERN ZONES. SHOWER/TSTM THREAT
BEGINS IN THE AFTERNOON ALONG THIS TROUGH...AND ENDS FOR MOST SPOTS
OVERNIGHT WHEN THE TRAILING COLD FRONT PASSES THROUGH. CAPPED POPS
IN THE CHC CATEGORY. PARAMETERS DURING THE AFTERNOON AND EARLY
EVENING SUPPORT THE POTENTIAL OF THUNDERSTORMS WITH STRONG WIND
GUSTS. LARGE HAIL WOULD BE LESS OF POSSIBILITY DUE TO RELATIVELY
HIGH WBZ/FREEZING LEVEL HEIGHTS. TSTM STRENGTH DIMINISHES AFTER
EARLY EVENING WITH LESS CAPE IN SPITE OF BETTER LIFT FROM THE
PASSING COLD FRONT. PWATS STILL RATHER HIGH...SO HEAVY DOWNPOURS
POSSIBLE IN ANY SHOWER.

ABOVE NORMAL TEMPERATURES WITH MUGGY CONDITIONS CONTINUE THROUGH
THIS PERIOD. WITH 850MB TEMPS OF 17-18C...PARTLY TO MOSTLY SUNNY
CONDITIONS FOR MOST OF THE DAY AND A SW FLOW...EXPECTING PARTS OF NE
NJ TO REACH INTO THE LOW-MID 90S...WITH LOW 90S IN THE CITY AND A
GOOD PORTION OF THE LOWER HUDSON VALLEY. MOST OTHER SPOTS EXPECTED
TO END UP AT 85-90. REGARDING HEAT ADVISORY CONCERNS IN THE
CITY...ALTHOUGH IT APPEARS THAT A DECENT PORTION OF THE CITY WILL
REACH A HEAT INDEX OF AT LEAST 95 FOR AN HOUR OR TWO TOMORROW
AFTERNOON...INDICES HAD FAILED TO REACH 95 MONDAY AFTERNOON. NO
ADVISORIES WILL THEREFORE BE POSTED AS PER LOCAL POLICY.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
COLD FRONT OFFSHORE WILL CONTINUE TO PUSH EAST ON WEDNESDAY AS HIGH
PRESSURE BUILDS IN. DRY CONDITIONS ARE EXPECTED THROUGH FRIDAY AS
THE CENTER OF THE HIGH MOVES OVER THE REGION AND OFF THE EAST COAST
BY THURSDAY WHILE ALOFT THERE WILL BE A RATHER ZONAL PATTERN.
HUMIDITY LEVELS DURING THIS PERIOD WILL EASE UP A BIT AS DEWPOINTS
DROP TO THE LOWER 60S ON WEDNESDAY...WITH SOME UPPER 50S DEWPOINTS
POSSIBLE ON THURSDAY. HOWEVER...THEY CREEP BACK UP TOWARDS THE LOWER
AND MIDDLE 60S AGAIN ON FRIDAY ON THE RETURN FLOW WITH THE HIGH
OFFSHORE.

A COLD FRONT WILL APPROACH THE AREA FRIDAY NIGHT INTO
SATURDAY...PUSHING OFFSHORE SOMETIME SATURDAY NIGHT. THERE IS SOME
MODEL CONSENSUS ON PUSHING THE COLD FRONT OFFSHORE SATURDAY
NIGHT...BUT THERE ARE DIFFERENCES THEREAFTER. THE 00Z ECMWF STALLS
THE FRONT JUST OFFSHORE AND THERE WOULD BE A CHANCE FOR POST-FRONTAL
RAIN THROUGH SUNDAY NIGHT. THE 12Z GFS AND CMC KEEP THE SYSTEM
PROGRESSIVE...ENDING THE RAIN SATURDAY NIGHT...KEEPING SUNDAY DRY.
GFS ENSEMBLE MEAN IS ACTUALLY MORE PROGRESSIVE WITH THE COLD
FRONT...PUSHING IT OFFSHORE DURING THE DAY SATURDAY...BUT ALSO ENDS
IT SATURDAY NIGHT. ALSO...MODELS DIFFER IN DEVELOPMENT AND PLACEMENT
OF LOW PRESSURE ALONG THE FRONTAL BOUNDARY...WHICH LEAD TO LARGE
DIFFERENCES IN PLACEMENT OF ANY HEAVY RAINFALL. ALTHOUGH THE GFS IS
MORE PROGRESSIVE...THE FRONT HAS SLOWED DOWN SIGNIFICANTLY FROM THE
PREVIOUS 06Z RUN. SO...GIVEN UNCERTAINTY WILL KEEP AT LEAST SLIGHT
CHANCE POPS IN FOR SUNDAY MORNING...DRYING OUT BY THE AFTERNOON.

TEMPERATURES WILL BE ABOVE NORMAL THROUGH SATURDAY.
THEREAFTER...BELOW NORMAL TEMPERATURES EXPECTED AS A CONTINENTAL
POLAR AIRMASS BUILDS IN.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
A SURFACE TROUGH WILL WEAKEN AS IT MOVES EAST TONIGHT. A COLD FRONT
APPROACHES LATE TUESDAY.

SHOWERS AND ISOLATED THUNDERSTORMS HAVE DEVELOPED. EXPECT SCATTERED
ACTIVITY ACROSS THE AREA THROUGH 22-23Z. OTHERWISE...VFR LATE THIS
AFTERNOON WITH SCATTERED TO BROKEN CU.

BY TONIGHT...PATCHY STRATUS AND FOG IS EXPECTED...ESPECIALLY LATER
ON AT NIGHT. MVFR OR IFR POSSIBLE...ESPECIALLY OUTSIDE OF NYC METRO
TERMINALS.

VFR TUESDAY MORNING AS ANY MORNING STRATUS AND FOG BURNS OFF.

SOUTH TO SOUTHWEST WINDS AROUND 10 KT THIS AFTERNOON LIGHTEN
TONIGHT. SOUTHWEST WIND PERSISTS TUESDAY MORNING...GENERALLY UNDER
10 KTS.

     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: POSSIBLE AMENDMENTS FOR SCATTERED SHOWERS/
THUNDERSTORMS THROUGH 22Z OR SO.

KLGA FCSTER COMMENTS: POSSIBLE AMENDMENTS FOR SCATTERED SHOWERS/
THUNDERSTORMS THROUGH 22Z OR SO.

KEWR FCSTER COMMENTS: WINDS ARE EXPECTED TO REMAIN SOUTH TO
SOUTHWEST. HOWEVER...SOUTHEAST SEA BREEZE WILL APPROACH THE AIRPORT
AND WILL NEED TO BE WATCHED. POSSIBLE AMENDMENTS FOR SCATTERED
SHOWERS/THUNDERSTORMS THROUGH 22Z OR SO.

KTEB FCSTER COMMENTS: POSSIBLE AMENDMENTS FOR SCATTERED SHOWERS/
THUNDERSTORMS THROUGH 22Z OR SO.

KHPN FCSTER COMMENTS: POSSIBLE AMENDMENTS FOR SCATTERED SHOWERS/
THUNDERSTORMS THROUGH 22Z OR SO.

KISP FCSTER COMMENTS: POSSIBLE AMENDMENTS FOR SCATTERED SHOWERS/
THUNDERSTORMS THROUGH 22Z OR SO.

.OUTLOOK FOR 18Z TUE THROUGH FRI...
.TUE AFTERNOON-TUE NIGHT...MAINLY VFR EXCEPT FOR SCATTERED LATE
AFTERNOON AND NIGHTTIME SHRA/TSRA.
.WED-FRI NIGHT...VFR CONDITIONS ARE EXPECTED.
.SAT...SUB VFR POSSIBLE IN SCATTERED SHRA/TSRA.

&&

.MARINE...
SUB-SCA CONDITIONS EXPECTED ON THE WATERS THROUGH THE FORECAST
PERIOD WITH A RELATIVELY WEAK PRESSURE GRADIENT MOST OF THE TIME.
THERE COULD BE SHOWERS AND TSTMS TUESDAY NIGHT...AND AGAIN LATE
FRIDAY INTO SATURDAY AS A FRONT APPROACHES.

&&

.HYDROLOGY...
ISOLATED/SCT SHOWERS AND TSTMS INTO THIS EVENING SHOULD BE
SHORT-LIVED. LOCALIZED MINOR URBANIZED/SMALL STREAM FLOODING WOULD
BE POSSIBLE. FLASH FLOODING THREAT LOOKS TO BE LOW.

ISO/SCT SHOWERS/TSTMS LATE TUESDAY/TUES NIGHT WOULD LIKELY RESULT IN
NO MORE THAT LOCALIZED MINOR URBANIZED/SMALL STREAM FLOODING.

NO HYDROLOGIC ISSUES EXPECTED WEDNESDAY THROUGH THE WEEKEND.

&&

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

&&

$$
SYNOPSIS...JC/JP
NEAR TERM...JC
SHORT TERM...JC
LONG TERM...JP
AVIATION...PW
MARINE...JC/JP
HYDROLOGY...JC/JP





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