Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 012055 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 455 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/...
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ISO/SCT CONVECTION DIMINISHES THIS EVENING FROM THE COMBINATION OF ATMOSPHERIC STABILIZATION...LOSS OF MOISTURE CONVERGENCE DUE TO DISSIPATING SURFACE TROUGH AND SEABREEZE BOUNDARIES...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.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
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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. THERE IS A MODERATE RISK OF RIP CURRENTS ON TUESDAY.
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&& .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 /21Z MONDAY THROUGH SATURDAY/...
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A SURFACE TROUGH WILL WEAKEN AS IT MOVES EAST TONIGHT. A COLD FRONT APPROACHES LATE TUESDAY. WIDELY SCATTERED SHRA/TSTM ACTIVITY WILL CONTINUE TO DEVELOP OFF THE SEABREEZE BOUNDARIES AND HIGHER ELEVATIONS THROUGH AROUND 23-00Z...BUT LIKELY WEAKEN AS THEY DRIFT EASTWARD. 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 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 23Z OR SO. KLGA FCSTER COMMENTS: POSSIBLE AMENDMENTS FOR SCATTERED SHOWERS/ THUNDERSTORMS THROUGH 23Z OR SO. KEWR FCSTER COMMENTS: SEABREEZE BOUNDARY IS JUST WEST OF THE AIRPORT...RESULTING IN 150-170 WINDS. THIS BOUNDARY MAY WAVER ACROSS THE AIRPORT THROUGH AROUND 23Z...BEFORE WINDS RETURN TO LIGHT SW. POSSIBLE AMENDMENTS FOR AN ISOLATED SHOWERS/THUNDERSTORMS THROUGH 23Z OR SO. KTEB FCSTER COMMENTS: POSSIBLE AMENDMENTS FOR AN ISOLATED SHOWERS/THUNDERSTORMS THROUGH 23Z OR SO. KHPN FCSTER COMMENTS: POSSIBLE AMENDMENTS FOR AN ISOLATED SHOWERS/THUNDERSTORMS THROUGH 23Z OR SO. KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. .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.
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&& .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...NV/PW MARINE...JC/JP HYDROLOGY...JC/JP

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