Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 201753 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 153 PM EDT WED AUG 20 2014 .SYNOPSIS... HIGH PRESSURE WILL BE ANCHORED OVER EASTERN NEW ENGLAND THROUGH THURSDAY. AN UPPER LEVEL DISTURBANCE MOVES THROUGH FOR FRIDAY. SURFACE HIGH PRESSURE BUILDS INTO THE REGION FOR THE WEEKEND...THEN SLOWLY SLIDES OFFSHORE EARLY TO MID NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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NO SIGNIFICANT CHANGES WITH NOON UPDATE. JUST TWEAKED TEMPS/TDS AND REMOVED POPS FROM ORANGE CO FOR THE REMAINDER OF THE DAY. DEVELOPING SE FLOW TODAY. WITH SUBSIDENCE HANGING ON...PARTICULARLY ACROSS CNTRL AND ERN AREAS...MOST OF THE CWA SHOULD BE PTCLDY AND DRY. ACROSS THE FAR WRN/NWRN FRINGE...FALLING HEIGHTS ALONG WITH UP TO 1000 J/KG OF SBCAPE PER THE NAM COULD SPRING SOME SHRA/TSTMS. MAIN THREAT STILL W OF THE CWA WITH THE EMBEDDED SHRTWV NOT ARRIVING TIL ABOUT 00Z. TEMPS RIGHT ABOUT OR JUST BLW CLIMO. FCST IS CLOSE TO THE GMOS25.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... INSTABILITY WANES WITH CONTINUED ONSHORE FLOW ALONG WITH A LOSS OF SFC HEATING. THEREFORE THE SHRTWV IS EXPECTED TO HAVE A MINIMAL EFFECT ATTM AND PRODUCE ONLY A FEW SHRA AS IT TRAVERSES THE CWA THIS EVE/TNGT. ANY TSTMS WOULD NEED TO BE ELEVATED DUE TO THE STABLE MARINE LAYER. AS A RESULT...HAVE NOT INCLUDED TSTMS IN THE FCST FOR TNGT. 00Z MODEL CONSENSUS IS THAT THE UPR LOW SPINNING OVER THE UP OF MI WILL DROP HEIGHTS ON THU AND ATTEMPT TO TRIGGER SHRA OR TSTMS. INSTABILITY WILL BE THE LIMITING FACTOR...WITH A MARINE STRATUS DECK LIKELY PENETRATING ALMOST THE ENTIRE CWA. INCLUDED TSTMS ONLY ON THE WRN AND NRN PERIPHERY OF THE CWA...WITH ONLY SHRA ELSEWHERE. WHERE THE INSTABILITY DOES MATERIALIZE...THE SETUP IS RIPE FOR MULTICELLULAR HVY RAINERS IN A LOW SHEAR ENVIRONMENT AND PW/S ABOUT 125-150 PERCENT OF NORMAL. TEMPS COOLER DUE TO THE CLOUDS AND ONSHORE FLOW. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... DEEP UPPER TROUGH IN PLACE FOR THURSDAY NIGHT...WITH WEAK CUT OFF UPPER LOW WEAKENING OVER THE EASTERN GREAT LAKES REGION INTO FRIDAY MORNING.. AT THE SURFACE...HIGH PRESSURE OVER SOUTHEASTERN CANADA WILL BUILD SOUTH INTO THE NORTHEAST. UPPER TROUGH WILL SET OFF SOME SHOWERS THURSDAY NIGHT INTO FRIDAY AFTERNOON...MAINLY FOR WESTERN SECTIONS. SOME SURFACE BASED CAPE...A FEW HUNDRED TO JUST UNDER 1000 J/KG DEPENDING ON WHICH MODEL YOU LOOK AT...WILL ALLOW FOR SOME ISOLATED THUNDERSTORMS EARLY THURSDAY NIGHT. WITH A LACK OF ANY STRONG LIFTING MECHANISM...THE CHANCE FOR ANY THUNDERSTORMS SHOULD DIMINISH AS THE SUN SETS. OMEGA BLOCK IN THE UPPER LEVELS WILL ALLOW HIGH PRESSURE TO CONTINUE TO SLOWLY BUILD INTO THE REGION FOR THE WEEKEND AND INTO EARLY NEXT WEEK...WITH DRY CONDITIONS IN STORE. AN EXTENDED NORTHERLY FLOW WILL MEAN BELOW NORMAL TEMPERATURES FOR THIS TIME OF YEAR FOR THE WEEKEND. HIGHS WILL BE IN THE LOWER TO MIDDLE 70S ON SATURDAY...AND SLIGHTLY WARMER SUNDAY. LOWS SATURDAY NIGHT AND SUNDAY NIGHT WILL BE IN THE UPPER 50S TO LOWER 60S...EVEN IN THE NYC METRO REGION. THE HIGH PUSHES OFF THE NORTHEAST COAST MONDAY NIGHT INTO TUESDAY. THE RETURN FLOW WILL BRING TEMPERATURES BACK UP TO MORE NORMAL VALUES FOR THIS TIME OF YEAR. A COLD FRONT APPROACHES FOR THE MIDDLE OF THE WEEK...BUT CONDITIONS SHOULD REMAIN DRY. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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VFR AS HIGH PRESSURE REMAINS OVER THE AREA. SCT CU 040-050 MAINLY NORTH OF THE NY METRO OVER THE HILLIER TERRAIN. CONVECTION OVER CENTRAL PA AND WESTERN NY WILL WEAKEN THIS EVENING AS IT APPROACHES THE PA/NJ BOARDER TOWARDS 03Z. SCATTERED SHOWERS COULD REACH THE NY METRO TOWARDS MIDNIGHT. THESE ARE NOT INCLUDED IN TAFS AS THE PROBABILITY OF THIS IS ONLY 30% AT THIS TIME AND THEY ARE NOT EXPECTED TO AFFECT FLIGHT CATEGORY. THURSDAY MORNING COULD START OFF WITH SOME CIGS AROUND 030...THESE SHOULD RISE SLIGHTLY TO AT LEAST 035-040 BY AFTERNOON. 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: HIGH CONFIDENCE IN WINDS THIS AFTN. SPEED AVERAGE JUST BELOW 10 KT...THOUGH EXPECT OCNL 10-12 KT DURING FOR THE LATE AFTN DEPARTURE BANK. KLGA FCSTER COMMENTS: WIND DIRECTION WILL VARY 20 DEGREES OF THE FCST MEAN. KEWR FCSTER COMMENTS: HIGH CONFIDENCE IN WIND DIRECTION BEING 30-40 DEGREES RIGHT OF 130 MAGNETIC THIS AFTERNOON. KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. .OUTLOOK FOR 18Z THU THROUGH MON... .THU AFTN-NGT...VFR. SCATTERED TSTMS MAINLY SOUTH AND WEST OF THE NY METRO. .FRI-MON...VFR.
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&& .MARINE... WINDS AND SEAS BLW SCA LVLS THRU THU. SUB-SCA CONDITIONS EXPECTED FRI THROUGH THE DAY ON SATURDAY. A PERSISTENT NORTHEASTERLY FLOW WILL ALLOW WAVES TO BUILD TO 5 FT FOR THE CENTRAL AND EASTERN OCEAN ZONE SATURDAY NIGHT THROUGH THE DAY ON MONDAY. GUSTS ON SATURDAY WILL REACH THE LOWER 20 KT RANGE...AND SLIGHTLY LESS ON SUNDAY. GUSTS AT OR JUST ABOVE 25 KT ARE POSSIBLE FOR THE WEEKEND...BUT DOES NOT LOOK LIKELY AS OF NOW. GUSTS DIMINISH INTO THE BEGINNING OF THE WORK WEEK AS THE CENTER OF HIGH PRESSURE MOVES OVER THE WATERS. && .HYDROLOGY... A FEW TSTMS ARE POSSIBLE THU...MAINLY ACROSS THE HUDSON VALLEY INTO NJ AWAY FROM THE COAST. ANY TSTMS WILL HAVE THE POTENTIAL TO PRODUCE LOCALLY HVY RAIN...HOWEVER BASIN AVE PCPN OF LESS THAN 1/4 INCH IS EXPECTED ATTM. THE POTENTIAL EXISTS FOR MINOR POOR DRAINAGE FLOODING FROM ANY OF THIS TSTM ACTIVITY. NO SIGNIFICANT RAINFALL IS EXPECTED IN THE EXTENDED. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...JMC/JP NEAR TERM...JMC/PICCA/JP SHORT TERM...JMC LONG TERM...JP AVIATION...TONGUE/PW MARINE...JMC/JP HYDROLOGY...JMC/JP

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