Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 261959 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 359 PM EDT TUE MAY 26 2015 .SYNOPSIS... BERMUDA HIGH REMAINS ANCHORED WELL OFF THE EAST COAST THROUGH THURSDAY. A WEAK COLD FRONT WILL APPROACH THE AREA FROM THE WEST WEDNESDAY NIGHT...AND DISSIPATE ACROSS THE AREA ON THURSDAY. A STRONGER COLD FRONT WILL THEN IMPACT THE AREA SUNDAY INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... DAYTIME HEATING HAS LED TO AROUND 1000 J/KG OF SBCAPE AND ABOUT 500 J/KG OF MLCAPE PER 19Z SPC MESOANALYSIS ACROSS THE FAR NW INTERIOR. A FEW SHOWERS AND THUNDERSTORMS HAVE DEVELOPED IN THIS REGION. HAVE CONTINUED WITH LOW CHANCE POPS FOR THE REMAINDER OF THE AFTERNOON INTO THIS EVENING. FORCING IS RATHER WEAK...MAINLY FROM DIFFERENTIAL HEATING. CONVERGENCE FROM THE SEA BREEZE MOVING INTO THE INTERIOR MAY ALSO TRIGGER A SHOWER OR A STORM ACROSS THE INTERIOR AND POSSIBLY SOUTHERN CT. LOSS OF DAYTIME HEATING WILL ALLOW ANY ACTIVITY TO DISSIPATE AFTER SUNSET. OTHERWISE...WITH DEEP LAYERED RIDGING OVER THE EAST COAST AND MARITIME INFLUENCE FURTHER SOUTH AND EAST...NO SHOWERS OR STORMS ARE EXPECTED THROUGH THIS EVENING. AFTER MIDNIGHT...A WEAK SHORTWAVE MAY MOVE OVERHEAD AROUND THE PERIPHERY OF THE UPPER LEVEL RIDGE. MUCH OF THE MODEL GUIDANCE KEEPS US DRY...BUT FEEL IT IS NOT COMPLETELY OUT OF THE QUESTION THAT A SHOWER OR STORM DEVELOPS WITH THIS SHORTWAVE AND WEAK ELEVATED INSTABILITY. HAVE CAPPED POPS AT SLIGHT CHANCE TO ACCOUNT FOR THIS. THE GFS IS THE WETTEST MODEL DURING THIS TIMEFRAME AND IS LIKELY OVERDOING QPF. PATCHY FOG IS ALSO POSSIBLE TOWARDS MORNING. THE FOG MAY BECOME LOCALLY DENSE NEAR THE COAST...BUT IT REMAINS ON UNCERTAIN HOW WIDESPREAD THIS WOULD END UP BEING. THERE IS A GREATER LIKELIHOOD FOR STRATUS TO DEVELOP WITH PERSISTENT ONSHORE FLOW...ESPECIALLY NEAR THE COAST. LOW TEMPERATURES WILL BE IN THE MIDDLE AND UPPER 60S. THERE IS A MODERATE RISK FOR METEOROLOGICAL ENHANCEMENT OF RIP CURRENT DEVELOPMENT AT ATLANTIC OCEAN BEACHES THROUGH THIS EVENING. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... POTENTIAL FOR CONVECTION INCREASES ON WEDNESDAY AS THE UPPER LEVEL RIDGE BEGINS TO MOVE FURTHER OFFSHORE. THE DEVELOPMENT OF A PRE- FRONTAL/THERMAL TROUGH WILL PROVIDE A SOURCE FOR LIFT IN THE AFTERNOON...MAINLY NORTH AND WEST OF THE CITY. CAPE VALUES IN THE MODELS DIFFER IN THE AFTERNOON AND THIS IS DUE TO HOW MUCH HEATING THEY FORECAST. THE NAM HAS MUCH HIGHER SBCAPE WITH ITS WARMER SURFACE TEMPERATURES IN COMBINATION WITH DEW POINTS IN THE MID 60S. FEEL CAPE VALUES MAY BE A BIT TOO HIGH IN THE NAM...BUT IT HAS THE RIGHT IDEA WITH ITS WARMER TEMPERATURES LEADING TO HIGHER AMOUNTS OF INSTABILITY. ANY MORNING CLOUDS WILL BREAK LATE MORNING AND EARLY AFTERNOON TO ALLOW FOR ENOUGH SUNSHINE TO REALIZE THIS HIGHER INSTABILITY. SHOWERS AND STORMS SHOULD DEVELOP IN THE AFTERNOON AND LINGER INTO THE AFTERNOON WITH THE ABOVE IN MIND. SPC HAS THE INTERIOR OF NE NJ AND THE LOWER HUDSON VALLEY IN A MARGINAL RISK FOR SEVERE THUNDERSTORMS. AN ISOLATED SEVERE WIND GUST CANNOT BE RULED OUT HERE...BUT FEEL STORMS SHOULD REMAIN BELOW SEVERE LIMITS. LOCALLY HEAVY RAINFALL IS POSSIBLE IN ANY STORM WITH URBANIZED MINOR FLOODING A POSSIBILITY. CHANCE POPS CONTINUE FOR MAINLY WEST OF THE HUDSON RIVER. THE QUESTION FOR WEDNESDAY EVENING IS HOW FAR EAST THE CONVECTION GETS. THE MARINE INFLUENCE AND PROXIMITY OF THE UPPER RIDGE WILL MOST LIKELY WEAKEN THE STORMS CONSIDERABLY AS THEY MOVE NEAR THE HUDSON RIVER. NO HIGHER THAN SLIGHT CHANCE POPS FORECAST IN THE EVENING EAST OF THE HUDSON. POPS DO INCREASE TO LOW CHANCE FOR EASTERN ZONES OVERNIGHT AS THE PRE-FRONTAL TROUGH REMAINS NEARBY AND ELEVATED INSTABILITY COULD PROMOTE DEVELOPMENT OF A FEW SHOWERS/STORMS. HIGH TEMPERATURES ON WEDNESDAY WILL BE IN THE MID AND UPPER 80S FROM NYC NORTH AND WEST AND MAINLY MIDDLE AND UPPER 70S ACROSS SOUTHERN CT AND LONG ISLAND. LOWS WEDNESDAY NIGHT WILL BE IN THE 60S. && .LONG TERM /THURSDAY THROUGH TUESDAY/... A HIGH AMPLITUDE RIDGE ALONG THE EASTERN SEABOARD WILL EXPAND WESTWARD BACK INTO THE MS RIVER VALLEY AS SHORT WAVE ENERGY OVER THE GREAT LAKES DAMPENS AND LIFTS TO THE NE THU. THIS WILL ALLOW THE SUBTROP RIDGE TO REMAIN IN PLACE THROUGH NEXT WEEKEND...PUMPING IN WARM...HUMID AIR ACROSS THE REGION. A WEAK COLD FRONT WILL MOVE ACROSS THE AREA ON THU BEFORE DISSIPATING OFFSHORE ON FRI. THERE MAY BE A FEW SHOWERS OR THUNDERSTORMS THROUGH THU EVE...BUT DRY AIR LOOKS TO BE A LIMITING FACTOR. HEIGHTS BUILD ALOFT FRI INTO SAT WITH STRONG SUBSIDENCE CAPPING THE AIRMASS. ANY CONVECTION WILL BE ISOLATED...DIURNAL IN NATURE...AND LIKELY WELL INLAND. FORECAST DILEMMA REMAINS THE TIMING OF A STRONGER COLD FRONT SAT NIGHT INTO SUN. THE 12Z OPERATIONAL GFS STILL REMAINS THE FASTER...AND MORE AGGRESSIVE SOLUTION. HOWEVER...DEFERRED TO THE SLOWER ECMWF WHICH HAS MAINTAINED THE BEST RUN-TO-RUN CONTINUITY. THE ECMWF DOES NOT BRING THE FRONT THROUGH UNTIL SUN AFT AND THEN KEEPS IT IN CLOSE PROXIMITY THROUGH EARLY NEXT WEEK. THERE IS THE POTENTIAL FOR AN ORGANIZED RAINFALL EVENT LATE IN THE WEEKEND INTO EARLY NEXT WEEK AS THE COLD FRONT MOVES INTO THE AREA. CONDITIONS WILL REMAIN UNSEASONABLY WARM THROUGH SAT...THEN COOLS DOWN SUN INTO MON BEHIND THE COLD FRONT. && .AVIATION /20Z TUESDAY THROUGH SUNDAY/... PERSISTENT OFFSHORE HIGH PRESSURE THROUGH THE TAF PERIOD WITH VFR THROUGH TONIGHT. ONLY EXCEPTION WOULD BE KSWF WHERE THERE IS A POSSIBILITY OF A SHOWER OR THUNDERSTORM BEFORE EVENING BUT CONFIDENCE IN TIMING AND EXACT LOCATION IS PRETTY LOW. THE CONTINUED S-SW FLOW OF 10-15 KT GUSTING TO 20-25 KT WILL LOWER THIS EVENING AND WEDNESDAY. CONFIDENCE IS HIGH WITH THE CATEGORY FORECAST AND MODERATE WITH WINDS. HOWEVER...THE CONFIDENCE FOR CATEGORY LOWERS LATE TONIGHT AND WEDNESDAY. THERE WILL BE THE POTENTIAL FOR LOW STRATUS/FOG AS WELL AS SOME SHOWERS. THERE IS UNCERTAINTY IN TIMING WHERE THE LOWERING OF CATEGORY COULD START/END 2-3 HRS DIFFERENT FROM FORECAST AND THE CATEGORY ITSELF COULD BE 1-2 CATEGORIES DIFFERENT FROM OBSERVED AT TIMES. 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: TIMING OF WIND GUSTS MAY BE OFF BY AN HOUR OR TWO. PEAK WIND GUSTS MAY BE A FEW KTS HIGHER THAN FORECAST. KLGA FCSTER COMMENTS: TIMING OF WIND GUSTS MAY BE OFF BY AN HOUR OR TWO. PEAK WIND GUSTS MAY BE A FEW KTS HIGHER THAN FORECAST. KEWR FCSTER COMMENTS: TIMING OF WIND GUSTS MAY BE OFF BY AN HOUR OR TWO. PEAK WIND GUSTS MAY BE A FEW KTS HIGHER THAN FORECAST. KTEB FCSTER COMMENTS: TIMING OF WIND GUSTS MAY BE OFF BY AN HOUR OR TWO. PEAK WIND GUSTS MAY BE A FEW KTS HIGHER THAN FORECAST. KHPN FCSTER COMMENTS: TIMING OF WIND GUSTS MAY BE OFF BY AN HOUR OR TWO. PEAK WIND GUSTS MAY BE A FEW KTS HIGHER THAN FORECAST. KISP FCSTER COMMENTS: TIMING OF WIND GUSTS MAY BE OFF BY AN HOUR OR TWO. PEAK WIND GUSTS MAY BE A FEW KTS HIGHER THAN FORECAST. .OUTLOOK FOR 20Z WEDNESDAY THROUGH SUNDAY... .WEDNESDAY-WEDNESDAY NIGHT...CHANCE OF AFTERNOON AND EARLY EVENING SHRA/TSTM...MAINLY NORTH AND WEST OF THE NYC METRO TERMINALS. SOUTHERLY WIND GUSTS UP TO 25 KT. .THURSDAY-SATURDAY...THIS IS A CHANCE OF LATE NIGHT AND EARLY MORNING MVFR OR LOWER STRATUS AND/OR FOG. THERE IS A SLIGHT CHANCE OF AFTERNOON AND EVENING SHRA/TSTM THU AND SAT. WIND GUSTS 15-20 KT THU AFTN AND SAT AFTN. .SATURDAY NIGHT...MVFR OR LOWER POSSIBLE WITH CHANCE OF SHRA/TSTM. .SUNDAY...MVFR OR LOWER POSSIBLE WITH CHANCE OF SHRA/ISOLATED TSRA. && .MARINE... THE SCA ON THE OCEAN WATERS HAS BEEN EXTENDED THROUGH WEDNESDAY NIGHT. WIND GUSTS AROUND 25 KT ARE LIKELY INTO THIS EVENING AND THEN AGAIN ON WEDNESDAY AND WEDNESDAY EVENING WITH PROLONGED SOUTHERLY FLOW. SEAS WILL ALSO BUILD TO 5 FT TONIGHT AND REMAIN NEAR 5 FT THROUGH WEDNESDAY NIGHT. THE SCA ON THE NY HARBOR AND SOUTH SHORE BAYS CONTINUES THROUGH MIDNIGHT TONIGHT. THIS MAY BE ABLE TO BE CANCELLED EARLIER IF THE STRONGER WINDS DO NOT PAN OUT THIS EVENING. WINDS MAY ALSO APPROACH SCA LEVELS ON THE NY HARBOR AND SOUTH SHORE BAYS AGAIN ON WEDNESDAY AFTERNOON. THERE IS ALSO THE POTENTIAL FOR AREAS OF DENSE FOG TO FORM ON THE WATERS LATE TONIGHT INTO WEDNESDAY MORNING. CONFIDENCE REMAINS LOW ON THIS AND FOR NOW HAVE CONTINUED TO FORECAST PATCHY FOG. MARGINAL SCA CONDITIONS ON THE OCEAN WATERS POSSIBLE THU-SUN WITH A MODERATE SLY FLOW. THERE WILL BE A BRIEF PERIOD OF OFFSHORE WINDS THU NIGHT BEHIND A DISSIPATING COLD FRONT. && .HYDROLOGY... GENERALLY LESS THAN TWO TENTHS OF AN INCH OF BASIN AVERAGE RAINFALL IS EXPECTED THROUGH WEDNESDAY. HOWEVER ANY STRONGER CONVECTION THAT FORMS...ESPECIALLY IF THERE IS ANY TRAINING OF STORMS...COULD LEAD TO MINOR FLOODING OF URBAN AND/OR POOR DRAINAGE AREAS. THERE IS THE POTENTIAL FOR AN ORGANIZED RAINFALL EVENT LATE IN THE WEEKEND INTO EARLY NEXT WEEK AS COLD FRONT MOVES INTO THE AREA. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ350-353- 355. SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ338-345. && $$ SYNOPSIS...DS/DW NEAR TERM...DS SHORT TERM...DS LONG TERM...DS/DW AVIATION...JM MARINE...DS/DW HYDROLOGY...DS/DW

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