Area Forecast Discussion
Issued by NWS Upton, NY

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686 FXUS61 KOKX 041928 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 328 PM EDT WED MAY 4 2016 .SYNOPSIS... A SERIES OF LOWS WILL TRACK TO THE SOUTH OF LONG ISLAND THROUGH THURSDAY. AN AREA OF LOW PRESSURE WILL SLOWLY TRACK FROM NEAR THE MID ATLANTIC COAST THURSDAY NIGHT INTO SOUTHERN NEW ENGLAND BY SATURDAY. A COLD FRONT APPROACHES FROM THE NORTHWEST SATURDAY NIGHT...THEN CROSSES THE AREA ON SUNDAY...FOLLOWED BY HIGH PRESSURE BUILDING IN TO THE SOUTH INTO TUESDAY. A WARM FRONT APPROACHES FROM THE SOUTHWEST ON TUESDAY AS WELL. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AREA UNDER BROAD SYNOPTIC SCALE LIFT WITH A DEEPENING FULL LATITUDE TROF ACROSS THE TN AND OH VALLEYS...AND MULTIPLE WAVES OF LOW PRESSURE PASSING SE OF THE AREA. THIS COUPLED WITH A COLD SFC HIGH ACROSS THE NE WILL ALLOW FOR OVERRUNNING RAIN/DRIZZLE TO EXPAND ACROSS THE AREA THIS AFTERNOON. THE ONE CAVEAT THOUGH IS THAT THERE IS SOME ELEVATED INSTABILITY ALOFT COUPLED WITH UPPER JET DYNAMICS. LATEST RADAR IMAGERY DEPICTS HEAVIER SHOWERS DEVELOPING ACROSS SRN NJ...PROPAGATING NE. SHOULD THESE HOLD TOGETHER THERE COULD BE BRIEF HEAVY RAINFALL FROM NYC METRO EAST ACROSS LI/CT MID TO LATE AFT. HIGHS REMAIN ON TAP FOR THE UPPER 40S TO LOWER 50S...WHICH 10-15 DEGREES BELOW NORMAL. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... THE AFOREMENTIONED SHORTWAVE AND UPPER JET STREAK BOTH EXITS TO THE NNE THIS EVENING BRINGING SIGNIFICANT RAINFALL TO AN END FROM SW TO NE. WILL BE LEFT AGAIN WITH DRIZZLE AND LIGHT RAIN. ALSO EXPECT PATCHY FOG TO DEVELOP LATE TONIGHT AS WELL. LOWS TONIGHT WERE BASED ON A BLEND OF MAV/ECS/MET GUIDANCE AND NAM 2-METER TEMPERATURES...AND SHOULD BE NEAR TO SLIGHTLY BELOW NORMAL. THERE IS A BIT MORE UNCERTAINTY WITH WHETHER THURSDAY WILL BE MAINLY GRAY AND DAMP...OR WILL THE AFTERNOON FEATURE ANOTHER ROUND OF MORE SIGNIFICANT RAINFALL DUE TO THE PASSAGE OF ANOTHER 700-500 HPA SHORTWAVE. THE ANSWER WILL BE DETERMINED BY THE EXACT TRACK/TIMING/ORIENTATION/STRENGTH OF A DEVELOPING CUTOFF LOW PROGGED TO TRACK FROM E TN/KY/FAR W NC/VA THURSDAY MORNING TO THE CAROLINA COAST BY THURSDAY EVENING. THE ISSUE IS...THE MODELS DIFFER IN THE EXACT TRACK/TIMING/ORIENTATION AND STRENGTH OF THIS CUTOFF...AND THIS IMPACTS THE TIMING/PLACEMENT OF A 700-500 HPA SHORTWAVE ROTATING AROUND IT. THE ECMWF GIVES THE AREA MORE OF A DIRECT IMPACT...THE GFS/CMC-REG MORE OF A MISS THAN A HIT AND THE NAM IS IN BETWEEN. GIVEN THE UNCERTAINTY...POPS HAVE BEEN LIMITED TO CHANCE FOR NOW. FOR HIGHS ON THURSDAY A BLEND OF ECS/MET/MAV GUIDANCE...NAM 2-METER TEMPERATURES AND A MIX DOWN FROM 975-950 HPA PER BUFKIT SOUNDINGS WAS USED. HIGHS SHOULD AGAIN BE AROUND 10-15 DEGREES BELOW NORMAL. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT WITH THE H5 PATTERN ACROSS NOAM THROUGH THE WEEKEND. A HIGHLY AMPLIFIED BLOCKY PATTERN STARTS OFF THE PERIOD WITH CUTOFF LOW PRES SYSTEMS OVER EACH U.S. COAST...WITH RIDGING OVER THE PLAINS AS WELL AS THE CENTRAL ATLANTIC. THE RIDGE OVER THE MIDDLE OF THE CONUS BREAKS DOWN AS IT TRIES TO MOVE EWD WITH A SPLIT FLOW BECOMING ESTABLISHED OUT WEST OVER THE WEEKEND. AN UNSETTLED PATTERN WITH BELOW NORMAL TEMPS WILL PREVAIL THROUGH THE END OF THE WEEK WITH THE AFOREMENTIONED CUTOFF OVER THE MID ATLANTIC COAST THU NIGHT...GRADUALLY LIFTING N WHILE WEAKENING FRI AND EVENTUALLY CONSOLIDATING WITH A TROUGH DIGGING OUT OF CENTRAL CANADA. AS ONE WAVE OF LOW PRES DEPARTS THU NIGHT...THERE SHOULD STILL BE WEAK LIFT AND PLENTY OF LOW LEVEL MOISTURE AROUND FOR LIGHT RAIN/DRIZZLE...SO HAVE MAINTAINED THIS IN THE FORECAST. MEANWHILE...ANOTHER AREA OF LOW PRES DEVELOPS OVER THE CAROLINAS AND SLOWLY TRACKS UP THE EAST COAST ON FRI. THIS SHOULD BRING ANOTHER ROUND OF RAINFALL TO THE AREA AND DUE TO INCREASED CONFIDENCE IN RAINFALL ON FRI...HAVE INCREASED POPS TO LIKELY. TRACK AND STRENGTH DISCREPANCIES REMAIN WHICH WILL IMPACT THE WIND FORECAST AND SUBSEQUENTLY...TIDAL PILING. SEE TIDES SECTION BELOW FOR MORE INFORMATION ON COASTAL FLOODING LATE THIS WEEK. DUE TO THE DOWNSTREAM BLOCK OVER THE ATLANTIC...THE SYSTEM WILL BE SLOW TO MOVE OUT...ALTHOUGH AN UPSTREAM KICKER DIVING OUT OF CANADA ON SAT SHOULD HELP. LOW CHC/SCHC POPS SAT DUE TO COOL POOL ALOFT FOLLOWED BY A COLD FRONT TRACKING THROUGH LATE SAT NIGHT INTO SUN. RIDGING THEN RETURNS FOR THE REMAINDER OF THE WEEKEND AND INTO NEXT WEEK WITH NEAR TO ABOVE NORMAL TEMPERATURES. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... LOW PRESSURE AND A NEARLY STATIONARY FRONT WILL BOTH REMAIN SOUTH OF LONG ISLAND THROUGH THE PERIOD...WHILE ANOTHER LOW APPROACHES THE MID ATLANTIC REGION FROM THE WEST. IFR CONDS TO START AT KEWR/KLGA/KISP AND MVFR ELSEWHERE. AREA OF RAIN AND EMBEDDED HEAVIER SHOWERS/TSTMS WILL IMPACT MAINLY KISP/KGON AND SIDESWIPE NYC METRO LATE THIS AFTERNOON. SEEING FREQUENT LIGHTNING WITH SOME CELLS OFF THE NJ COAST...AND THERE SHOULD BE ENOUGH INSTABILITY TO ALLOW FOR THUNDER AT KISP MAINLY 20Z-21Z...POSSIBLY AT KGON 22Z-23Z. THEREAFTER...EXPECT MAINLY IFR CONDS TONIGHT WITH SOME PATCHY DRIZZLE...BUT CANNOT RULE OUT PERIODS OF MVFR. MVFR CONDS MORE LIKELY TO RETURN A COUPLE OF HRS AFTER DAYBREAK THU AS DEEPER MOISTURE WITH THE OFFSHORE LOW PULLS OFF A LITTLE TO THE EAST...BUT IT IS UNCERTAIN IF CONDS FARTHER EAST AT KGON WILL IMPROVE. E TO NE WINDS INCREASE INTO THIS EVENING AND SHOULD SLOWLY BACK MORE NE TO NNE. GUSTS AROUND OR JUST OVER 20 KT LIKELY. ...NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.WEATHER.GOV/ZNY/N90 (LOWER CASE) KJFK FCSTER COMMENTS: AMD LIKELY FOR CHANGING FLIGHT CAT. KLGA FCSTER COMMENTS: AMD LIKELY FOR CHANGING FLIGHT CAT. KEWR FCSTER COMMENTS: AMD LIKELY FOR CHANGING FLIGHT CAT. KTEB FCSTER COMMENTS: AMD LIKELY FOR CHANGING FLIGHT CAT. KHPN FCSTER COMMENTS: AMD LIKELY FOR CHANGING FLIGHT CAT. KISP FCSTER COMMENTS: AMD LIKELY FOR CHANGING FLIGHT CAT. HIGH CONFIDENCE ON TIMING OF THUNDER. .OUTLOOK FOR 18Z THU THROUGH MON... .THU AFTERNOON THROUGH SUNDAY MORNING...PERIODS OF RAIN/FOG/LOW CLOUDS WITH MVFR OR LOWER CONDITIONS. NE WINDS G20 KT POSSIBLE WED EVENING AND ALSO AT TIMES THU AND FRI. .SUNDAY AFTERNOON/NIGHT...COLD FRONTAL PASSAGE SHOULD FINALLY BRING AN END TO DISMAL CONDITIONS...WITH CONDITIONS IMPROVING TO VFR AND NW WINDS G20KT. .MON...VFR. W WINDS G25KT. && .MARINE... SMALL CRAFT CONDITIONS WILL CONTINUE ON THE COASTAL OCEAN WATERS THROUGH THURSDAY...WITH GUSTS OF 25-30 KT AND SEAS OF 4-6 FT. ON THE NON-OCEAN WATERS...GUSTS SHOULD PEAK AT 20 KT TODAY...THEN COULD REACH 25 KT TONIGHT...AND POSSIBLY AGAIN ON THURSDAY. AT THIS TIME...CONFIDENCE IN 25 KT GUSTS ON THE NON-OCEAN WATERS TONIGHT AND THURSDAY IS NOT HIGH ENOUGH TO ISSUE A SMALL CRAFT ADVISORY THERE. MARGINAL WIND GUSTS ARE POSSIBLE ON THE OCEAN WATERS AS LOW PRES APPROACHES FROM THE S ON FRI AND AGAIN ON SUNDAY BEHIND A COLD FRONT. OTHERWISE...THE LOW WILL BE CHURNING UP SEAS ON THE OCEAN AS IT SLOWLY LIFTS UP THE MID ATLANTIC COAST WITH ADVISORY LEVELS INTO SAT. SUB-ADVISORY CONDITIONS SHOULD RETURN BY MIDNIGHT SUN ALTHOUGH SEAS COULD BUILD AGAIN ON THE OCEAN LATE SUN. SUB- ADVISORY LEVELS ARE EXPECTED THROUGH THE PERIOD ON THE NON-OCEAN WATERS...ALTHOUGH GUSTS COULD GET CLOSE SUN AFTERNOON. && .HYDROLOGY... AROUND 1/4-1/2 INCH OF RAINFALL IS FORECAST THROUGH TONIGHT...WITH LOCALLY HIGHER AMOUNTS OF AN INCH OR MORE POSSIBLE IN AREAS EXPERIENCING STRONG CONVECTION. AREAS THAT DO RECEIVE LOCALLY HEAVY RAINFALL COULD EXPERIENCE PONDING OF WATER ON ROADWAYS...AND A VERY LOW CHANCE OF LOCALIZED MINOR FLOODING. ADDITIONAL MAINLY LIGHT TO MODERATE RAINFALL IS POSSIBLY AGAIN THURSDAY...WITH A LOW CHANCE OF LOCALLY HEAVY RAINFALL POSSIBLE. FOR NOW EXPECT AMOUNTS TO REMAIN BELOW 1/2 INCH ON THURSDAY. A QUARTER TO A HALF INCH OF RAINFALL IS POSSIBLE THU NIGHT AND FRI. ADDITIONAL RAINFALL OF LESS THAN AN INCH IS EXPECTED WITH A COLD FRONTAL PASSAGE OVER THE WEEKEND. NO HYDROLOGIC ISSUES EXPECTED. && .TIDES/COASTAL FLOODING... THE HIGHEST SPRING TIDE OF THE YEAR IS APPROACHING WITH THE NEW MOON ON FRIDAY. THE THREAT FOR MINOR COASTAL FLOODING WILL INCREASE DURING THE EVENING HIGH TIDES THROUGH FRIDAY...AND LIKELY CONTINUE INTO THIS WEEKEND. PERIODIC NE FLOW IS EXPECTED THROUGH LATE WEEK AS A SERIES OF LOW PRESSURE WAVES TRACKS TO THE SOUTH OF THE REGION. THE TIMING AND STRENGTH OF THESE WAVES WILL PREDICATE POTENTIAL FOR MODERATE COASTAL FLOODING...BUT THE THREAT IS THERE PARTICULARLY FOR THE SOUTH SHORE BAYS OF LONG ISLAND/QUEENS. 15 TO 20 KT E/ENE WINDS TODAY WILL RESULT IN MINOR COASTAL FLOODING ALONG VULNERABLE LOCALES OF THE SOUTH SHORE BAYS OF WESTERN LONG ISLAND/NYC WHERE TIDAL DEPARTURES OF 1 TO 1.5 FT ARE FORECAST...SO A COASTAL FLOOD ADVISORY HAS BEEN ISSUED THERE FOR THIS EVENINGS HIGH TIDE. COASTAL FLOOD BENCHMARKS LIKELY WILL JUST BEING REACHED ACROSS WESTERN LONG ISLAND SOUND AND NY HARBOR...EXCEPT FOR THE MANHATTAN/N QUEENS/BRONX COASTS...DURING THIS EVENINGS HIGH TIDE. TIDAL DEPARTURES OF AROUND 1/2 TO 1 FT ARE LIKELY IN THOSE TWO AREAS. FARTHER EAST ACROSS E LONG ISLAND SOUND AND THE EASTERN BAYS OF LONG ISLAND...IT APPEARS DEPARTURES WILL RUN AT LEAST A FEW TENTHS OF A FT BELOW LEVELS NEEDED TO REACH MINOR COASTAL FLOOD BENCHMARKS THIS EVENING. FOR THURSDAY EVENINGS HIGH TIDE...ASTRONOMICAL TIDES WILL BE AROUND 1/4-1/2 FT HIGHER THAN THIS EVENING...WHILE TIDAL DEPARTURES SHOULD REMAIN AROUND THE SAME LEVELS AS THIS EVENING. THIS SHOULD RESULT IN MORE WIDESPREAD MINOR COASTAL FLOODING ACROSS MOST COASTAL AREAS. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...COASTAL FLOOD ADVISORY FROM 6 PM TO 10 PM EDT THIS EVENING FOR NYZ075-080-178-179. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THURSDAY FOR ANZ350-353- 355. && $$ SYNOPSIS...MALOIT NEAR TERM...MALOIT/DW SHORT TERM...MALOIT LONG TERM...24 AVIATION...GOODMAN MARINE...24/MALOIT HYDROLOGY...24/MALOIT TIDES/COASTAL FLOODING...

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