Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 020005 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 805 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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SOME MINOR ADJUSTMENTS WITH POPS FOR CONVECTION...TEMPS...AND DEWPOINTS. OVERALL...FORECAST IS ON TRACK. ANY CONVECTION JUST EXPECTED TO BE ISOLATED AND EARLY IN THE EVENING WITH AGREEMENT WITH MULTIPLE MESOSCALE MODELS OF MOSTLY DRY CONDITIONS MID EVENING THROUGH THE REST OF THE NIGHT. 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 AROUND 1.5 TO 1.7 INCHES...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.
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&& .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. THERE IS A MODERATE RISK OF RIP CURRENTS ON TUESDAY. && .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 /00Z TUESDAY THROUGH SATURDAY/...
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A SURFACE TROUGH WILL DISSIPATE AS IT MOVES EAST OVERNIGHT. A COLD FRONT APPROACHES LATE TUESDAY. MVFR/IFR STRATUS/FOG LIKELY ALONG EASTERN TERMINALS...POSSIBLE ACROSS INTERIOR TERMINALS. ANY MORNING STRATUS AND FOG BURNS OFF WITH VFR CONDS. LIGHT SW WINDS TONIGHT INTO TUESDAY MORNING...GIVING WAY TO AFTERNOON SEABREEZE DEVELOPMENT ALONG THE COAST. INCREASING CHANCE FOR SCT SHRA/TSRA TUE EVENING ACROSS NYC TERMINALS AND TO THE W & NW. 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: SEABREEZE DEVELOPMENT EXPECTED BETWEEN 17Z AND 19Z. MAXING OUT AT 15 TO 18 KT AFTER 21Z. KLGA FCSTER COMMENTS: SEABREEZE DEVELOPMENT LIKELY BETWEEN 19Z AND 21Z. KEWR FCSTER COMMENTS: LOW PROBABILITY OF AFT SEABREEZE DEVELOPMENT. KTEB FCSTER COMMENTS: LOW PROBABILITY OF AFT SEABREEZE DEVELOPMENT. KHPN FCSTER COMMENTS: SEABREEZE DEVELOPMENT LIKELY BETWEEN 19Z AND 21Z. KISP FCSTER COMMENTS: SEABREEZE DEVELOPMENT EXPECTED BETWEEN 18Z AND 20Z. .OUTLOOK FOR 00Z WED THROUGH FRI... .TUE NIGHT...MAINLY VFR EXCEPT FOR SCATTERED EVE/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...
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ISOLATED/SCT SHOWERS AND TSTMS THIS EVENING SHOULD BE SHORT- LIVED. ISO/SCT SHOWERS/TSTMS LATE TUESDAY/TUES NIGHT WOULD LIKELY RESULT IN NO MORE THAN LOCALIZED MINOR URBANIZED/SMALL STREAM FLOODING. NO HYDROLOGIC ISSUES EXPECTED WEDNESDAY THROUGH THE WEEKEND.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...JC/JP NEAR TERM...JC/JM SHORT TERM...JC LONG TERM...JP AVIATION...NV/PW MARINE...JC/JP HYDROLOGY...JC/JP

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