Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 011739
AFDOKX

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

.SYNOPSIS...
A SURFACE TROUGH OVER THE AREA THIS AFTERNOON DISSIPATES AS IT
SHIFTS EAST TONIGHT. A COLD FRONT WILL APPROACH THE AREA ON
TUESDAY AND MOVES THROUGH TUESDAY NIGHT...WITH HIGH PRESSURE
BUILDING IN FOR THE LATTER HALF OF THE WEEK. ANOTHER COLD FRONT
WILL IMPACT THE REGION THIS WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MINOR CHANGES MADE WITH THIS UPDATE...MAINLY WITH CLOUD COVER AND
HOURLY TEMPS. A SHORTWAVE PASSING TO OUR SOUTH DURING THE FIST
HALF OF THIS AFTERNOON SHOULD PROVIDE SOME LIFT FOR AT LEAST THE
SOUTHERN ZONES...BUT HAS NOT RESULTED MUCH IN THE WAY OF SHOWERS
SO FAR. BUT MEANWHILE...WE CONTINUE TO DESTABILIZE WITH DAYTIME
HEATING AND HIGH DEWPOINTS. MODERATE CAPE IN A LOW SHEAR
ENVIRONMENT SHOULD RESULT IN SCT PULSE STORMS THIS AFTN. COULD BE
A FEW STRONGER STORMS...ALTHOUGH DUE TO THE WEAK SHEAR NOT
EXPECTING SEVERE. MORE IMPORTANTLY...PWATS WILL REMAIN AROUND 2
INCHES AND STORMS WILL BE MOVING SLOWER THAN YESTERDAY SO AN ISOLD
FLASH FLOOD THREAT REMAINS...MAINLY IN URBANIZED AREAS. NOT
WIDESPREAD ENOUGH FOR A WATCH HOWEVER.

LOOKS LIKE WIDESPREAD HEAT INDICES FALL JUST SHORT OF 95 IN THE
CITY THIS AFTN. THIS WILL NEED TO BE TAKEN INTO CONSIDERATION FOR
A POTENTIAL ADVISORY. THE UNCERTAINTY OF CLOUD COVER THIS AFTN AND
CONSEQUENTIAL HIGH TEMPS...PLUS MARGINAL CRITERIA INDICES FOR
TOMORROW COMPLICATE THE FORECAST.

THERE IS A MODERATE RISK OF RIP CURRENTS TODAY...DUE TO COMBINED 3
TO 5 FT SOUTHERLY WIND WAVES AND A BACKGROUND SE SWELL.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
SHRA/TSTMS DIMINISH AND SHIFT EWD DURING THE EVENING AS THE
ATMOSPHERE STABILIZES AND MOISTURE CONVERGENCE AND LIFT MOVE EAST.

THE HEAT AND HUMIDITY WILL CONTINUE THROUGH TUE WITH H85 TEMPS
REMAINING AROUND 17-18C AND MIXING TO THIS HEIGHT. CLOUD COVER
WILL INCREASE DURING THE AFTN AS A COLD FRONT APPROACHES FROM THE
W...BUT WE SHOULD STILL MAX OUT IN THE UPPER 80S TO LOWER 90S
ACROSS A GOOD PORTION OF THE FORECAST AREA.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
PCPN CHANCES DISSIPATE QUICKLY TUESDAY NIGHT AS AN UPPER LEVEL
TROUGH SWINGS THROUGH THE NORTHEAST...WHILE THE SURFACE LOW LIFTS
NORTH...DRAGGING ITS ASSOCIATED COLD FRONT THROUGH. GENERAL
AGREEMENT BETWEEN THE 00Z MODEL SOLUTIONS WITH THE FRONT MOVING
THROUGH BETWEEN 00-06Z. ALOFT...THE BETTER FORCING WITH THE
SHORTWAVE LOOKS TO REMAIN WELL NORTH OF THE REGION...WITH ONLY A
WEAK SHORTWAVE PASSING THROUGH DURING THE 00-06Z TIMEFRAME. AS
SUCH...WILL CAP POPS AT HIGHER END CHC THROUGH 03Z OVER AREAS
NORTH/WEST NYC METRO...THEN TAPER OFF WITH ALL AREAS BCMG DRY BY
06Z. LINGERING INSTABILITY UP TO 1000 J/KG COULD SEE AN ISO TSTM
STILL PSBL TUES EVENING RIGHT AHEAD OF THE FRONT. HIGH PRESSURE
QUICKLY BUILDS IN AT THE SURFACE WHILE A SEMI-ZONAL FLOW TAKES HOLD
BRIEFLY ALOFT.

BY WEDNESDAY SEEING DRYING CONDITIONS AS THE HIGH DEEPENS AND
RIDGING BUILDS ACROSS THE EASTERN HALF OF THE US. NO PCPN EXPECTED
WED-FRI UNDER SUCH A PATTERN. A QUICK SHOT OF COOLER AIR WED IN
THE WAKE OF THE FRONT WITH THE NORTHERLY FLOW WILL PUSH TEMPS BACK
A FEW DEGREES...THOUGH STILL REMAINING WELL ABOVE NORMAL. RISING
HEIGHTS WITH THE BUILDING RIDGE WILL INCREASE TEMPS ONCE AGAIN BY
WEEKS END...ESP WITH A STRONGER SURGE OF WARMER AIR WITH THE
SOUTHERLY FLOW SETTING UP AHEAD OF THE NEXT APPROACHING COLD
FRONT.

00Z GFS/CMC BEGIN APPROACHING THE COLD FRONT LATE FRIDAY...BRINGING
IT THROUGH BY SAT MORNING WHILE THE ECMWF REMAINS THE SLOWER
SOLUTION...MOVING THE FRONT THROUGH LATE SAT. QUESTION REMAINS TO
WHAT EXTENT THE RIDGE BUILDS...WITH THE GFS/CMC ACTUALLY SIDING
CLOSER TO MORE ZONAL FLOW WHILE THE ECMWF HAS A MORE PRONOUNCED
RIDGE WHICH IN TURN TAKE LONGER TO WEAKEN. FOR NOW...SIDED MORE
WITH THE ECMWF SOLUTION FOR TIMING...THOUGH EVEN THAT COULD BE A BIT
SLOW AND RIDGING OVERDONE...WITH A GOOD COMPROMISE BEING SWINGING
THE FRONT THROUGH SOMETIME SATURDAY. WITH THE UNCERTAINTY TOPPED
POPS AT CHC DURING THE DAY SAT...AND INTO THE FIRST HALF OF SUNDAY
NIGHT. BOTH THE GFS AND ECMWF HINT AT THE FRONT LINGERING JUST
OFFSHORE DURING THE DAY SUNDAY...AND THE ECMWF EVEN ON INTO MONDAY.
WILL MAINTAIN SLIGHT CHC POPS FOR SUNDAY MORNING TO ACCOUNT FOR THE
FRONTAL PLACEMENT. TEMPS QUICKLY REBOUND TO NEAR NORMAL TO SLIGHTLY
BELOW BY SUNDAY AS WELL WITH THE TROUGH USHERING IN MUCH COOLER
TEMPS ALOFT.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
A SURFACE TROUGH WILL WEAKEN AS IT MOVES EAST TONIGHT. A COLD FRONT
APPROACHES LATE TUESDAY.

SHOWERS AND THUNDERSTORMS ARE DEVELOPING...AND WILL BE SCATTERED
ACROSS THE AREA THROUGH 22-23Z. OTHERWISE...VFR THIS AFTERNOON WITH
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: AMENDMENTS FOR SCATTERED SHOWERS/
THUNDERSTORMS POSSIBLE THROUGH 22Z OR SO.

KLGA FCSTER COMMENTS: AMENDMENTS FOR SCATTERED SHOWERS/
THUNDERSTORMS POSSIBLE 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 AFTER 18-20Z. AMENDMENTS FOR SCATTERED
SHOWERS/THUNDERSTORMS POSSIBLE THROUGH 22Z OR SO.

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

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

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

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

&&

.MARINE...
GENERALLY SUB-SCA CONDITIONS THEN EXPECTED ON THE WATERS THROUGH
FRIDAY UNDER THE HIGH PRESSURE. AN OCCASIONAL GUST TO 25 KTS MIGHT
BE POSSIBLE ON THE OCEAN WATERS TUES EVENING RIGHT AHEAD OF THE
COLD FRONTAL PASSAGE.

WINDS INCREASE AHEAD OF THE NEXT FRONT LATE FRIDAY INTO
SATURDAY...WITH POSSIBLE GUSTS REACHING 25 KTS DURING THIS TIME.
WAVES/SEAS WILL BUILD IN RESPONSE TO INCREASING WINDS...THOUGH AT
THE MOMENT EXPECTING SEA CONDITIONS TO REMAIN SUB-SCA. WAVEWATCH WAS
QUICK TO BUILD THE SEAS...SIDING WITH THE QUICKER GFS SOLUTION...SO
DROPPED GUIDANCE AROUND 1 FT FOR FRI NIGHT/SAT TO REFLECT A SLOWER
SOLUTION.

&&

.HYDROLOGY...
BASIN AVERAGE RAINFALL IS EXPECTED TO BE AROUND 1/4 INCH TODAY.
DUE TO THE CONVECTIVE NATURE OF THE RAINFALL DISTRIBUTION...THERE
WILL BE AREAS THAT RECEIVE LITTLE TO NO RAINFALL...AND SOME AREAS
THAT COULD SEE OVER AN INCH.

MAINLY A MINOR URBAN AND POOR DRAINAGE FLOOD THREAT
TODAY...ALTHOUGH ISOLD FLASH FLOODING IS POSSIBLE WITH A WATER
LOADED ATMOSPHERE.

NO SIGNIFICANT PRECIPITATION RESULTING IN HYDROLOGIC ISSUES IS
CURRENTLY FORECASTED WED THROUGH THIS WEEKEND.

&&

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

&&

$$




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