Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 282216 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 616 PM EDT THU MAY 28 2015 .SYNOPSIS... A COLD FRONT MOVES THROUGH TONIGHT...THEN HIGH PRESSURE RETURNS THROUGH THE EARLY PORTION OF THE WEEKEND. HIGH PRESSURE THEN GIVES WAY TO A SLOW MOVING COLD FRONT APPROACHING FROM THE WEST. THE FRONT EVENTUALLY MOVES IN SATURDAY NIGHT AND STALLS NEAR THE REGION FOR SUNDAY INTO EARLY NEXT WEEK. HIGH PRESSURE BUILDS IN FROM THE NORTH LATE TUESDAY INTO MID NEXT WEEK AND ONCE AGAIN BECOMES ESTABLISHED OFFSHORE IN THE WESTERN ATLANTIC. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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SEVERE THUNDERSTORM WATCH 233 REMAINS IN EFFECT UNTIL 7 PM EDT THIS EVENING FOR NYC...SOUTHERN CT...LONG ISLAND AND MOST OF THE WATERS. THIS IS ESSENTIALLY OVER THE FRONTAL ZONE AND EAST OF THERE. ACROSS NYC...CONVECTION IS MORE ISOLATED BUT IS STILL PULSING UP OCCASIONALLY. STRONGEST CONVECTION STILL LOCATED ACROSS FAIRFIELD CT. THE COLD FRONT HAS MOVED THROUGH NORTHEAST NJ AND THE LOWER HUDSON VALLEY AS OF 6 PM. THE FRONT WILL CONTINUE TO SLOWLY PASS THE REMAINDER OF THE REGION THROUGH TONIGHT...CLEARING ALL OF LONG ISLAND AROUND OR SHORTLY AFTER MIDNIGHT AND THEN CLEARING THE OCEAN FORECAST WATERS BY DAYBREAK. LIFT ASSOCIATED WITH THIS FRONT PLUS SOME FROM A SHORTWAVE ALOFT WILL COMBINE WITH AVAILABLE CAPE TO PRODUCE SCATTERED THUNDERSTORMS...SOME POTENTIALLY SEVERE EARLY THIS EVENING. MAIN THREATS WITH THESE THUNDERSTORMS LOOK TO BE STRONG GUSTY WINDS AND BRIEF HEAVY DOWNPOURS. SMALLER HAIL COULD BE POSSIBLE AS WELL...GIVEN FORECAST WET BULB ZERO HEIGHTS AND THE AMOUNT OF CAPE IN THE HAIL GROWTH ZONE...BUT WITH MARGINAL DIRECTIONAL/SPEED SHEAR...SEVERE HAIL NOT AS LIKELY. EXPECTING DRY WEATHER BY 06Z WITH DIMINISHING CLOUDS. THERE IS A MDT RISK FOR RIPS AT THE OCEAN INTO THIS EVENING.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... DEEP-LAYERED RIDGING WILL PROVIDE THE SUBSIDENCE AND DRYING FOR A SUNNY DAY ON FRIDAY. MAV/NAM MOS BLEND IN GOOD AGREEMENT...AND WAS USED FOR HIGH TEMPS. HIGH TEMPS ABOVE AVERAGE...EVEN ACROSS THE COASTAL ZONES IN SPITE OF A LIGHT ONSHORE FLOW. CLOUDS AND MOISTURE THEN INCREASE FRIDAY NIGHT. REMAINING DRY...BUT PATCHY FOG DEVELOPING LATE AT NIGHT. STRATUS DEVELOPMENT ALSO POSSIBLE FOR THE COASTAL ZONES. && .LONG TERM /SATURDAY THROUGH THURSDAY/... THE JET STREAM STAYS NORTH OF THE REGION UNTIL EARLY NEXT WEEK WHEN IT WILL MOVE SOUTH FROM NEW ENGLAND AND THEN WITH RIDGING...THE JET PUSHES BACK NORTH OF THE AREA MID TO LATE NEXT WEEK. IN THE MID LEVELS...THE OFFSHORE RIDGE BECOMES LESS AMPLIFIED SATURDAY. THERE WILL BE A SHORTWAVE MOVING THROUGH SOUTHEAST CANADA FOR THE REST OF THE WEEKEND...RESULTING IN A BROADENING QUASI ZONAL FLOW ACROSS THE LOCAL REGION. ANOTHER SHORTWAVE APPROACHES CLOSER TO THE AREA MONDAY NIGHT AND MOVES ACROSS TUESDAY INTO TUESDAY NIGHT. UPPER LEVEL RIDGING BUILDS IN THEREAFTER. A SLOW MOVING COLD FRONT APPROACHES FROM THE WEST SATURDAY. THE PARENT LOW ATTACHED TO THIS FRONT WILL NOT BE THAT STRONG...SLOWLY DEEPENING WITH EASTWARD PROGRESS THROUGH SATURDAY AND THEN DEEPENING MORE WITHIN THE CANADIAN MARITIMES SUNDAY THROUGH SUNDAY NIGHT. THE COLD FRONT WILL BE MOVING WITHIN INTO THE REGION THROUGH THIS TIME. THE FRONT WILL THEN STALL NEAR THE REGION WITH LOW PRESSURE AND INVERTED TROUGH DEVELOPING AT THE SURFACE TO THE SOUTHWEST OF THE REGION ALONG THE FRONT MONDAY AND MONDAY NIGHT. HIGH PRESSURE GRADUALLY RETURNS TUESDAY FROM THE CANADIAN MARITIMES...BUT WEAKENS AND MOVES INTO THE WESTERN ATLANTIC MID TO LATE IN THE WEEK. IN TERMS OF WEATHER...THERE WILL BE A GRADUAL INCREASING CHANCE OF SHOWERS AND THUNDERSTORMS FIRST NORTH AND WEST OF NYC SATURDAY AHEAD OF THE COLD FRONT. FARTHER EAST ACROSS LONG ISLAND...CONDITIONS LIKELY REMAIN DRY THROUGH SATURDAY. THE CHANCES FOR SHOWERS AND THUNDERSTORMS INCREASE SATURDAY NIGHT ACROSS THE WHOLE FORECAST REGION AND FURTHERMORE ON SUNDAY. THUNDERSTORMS WILL BE MORE LIMITED SUNDAY AND SUNDAY NIGHT WITH DECREASING INSTABILITY WITH A MORE NORTHERLY AND EASTERLY FLOW DEVELOPING DURING THE DAY. THE INSTABILITY WILL BE LOCATED FARTHER SOUTH OF THE REGION. WITH THE FRONT STALLING NEAR THE REGION...SHOWERS REMAIN INTO EARLY NEXT WEEK...BEFORE BECOMING MORE MINIMAL TUESDAY AS THE FRONT PUSHES FARTHER SOUTH OF THE AREA WITH MAINLY DRY CONDITIONS RETURNING LATE TUESDAY NIGHT THROUGH NEXT THURSDAY. THE AIRMASS WILL STAY MOSTLY AS MARITIME TROPICAL THROUGH THE LONG TERM BUT COOLER FOR MONDAY AND TUESDAY NEXT WEEK. HIGHS WELL INTO 70S AND INTO LOWER 80S SATURDAY BUT UPPER 60S TO LOWER 70S SUNDAY. HIGHS LOWER INTO MAINLY THE 60S EARLY NEXT WEEK TRENDING BACK TO NEAR NORMAL VALUES. LOWS WITHIN THE 60S SATURDAY NIGHT AND WITHIN THE 50S ON AVERAGE SUNDAY NIGHT THROUGH EARLY NEXT WEEK. THEN THEY TREND BACK TO NORMAL AS WELL MID TO LATE NEXT WEEK. && .AVIATION /22Z THURSDAY THROUGH TUESDAY/... A COLD FRONT WILL APPROACH LATE THIS AFTERNOON AND PASS TONIGHT BEFORE DISSIPATING OFFSHORE ON FRIDAY. MAINLY VFR LATE THIS AFTERNOON AND EARLY EVENING...WITH THE EXCEPTION OF PESKY LINGERING STRATUS OVER EASTERN LI AND SE CT COASTS. THUNDERSTORMS WILL REMAIN ISOLATED TO SCATTERED...WITH TIMING FOR ANY THUNDERSTORM TO IMPACT THE AIRPORTS THRU 22Z OR 23Z. THEN SKIES CLEAR TONIGHT AND THROUGH FRIDAY. SOUTH WINDS SHIFT TO THE NORTH THIS EVENING. NORTHEAST WINDS ARE EXPECTED FRIDAY MORNING. 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: AMENDMENTS FOR ANY THUNDERSTORMS ARE POSSIBLE THROUGH 22Z OR 23Z. SOUTH WINDS SHIFT THIS EVENING...AND TIMING OF ANY WIND SHIFT MAY BE OFF AN HOUR OR TWO. GUSTS MAY BE OCCASIONAL. KLGA FCSTER COMMENTS: AMENDMENTS FOR ANY THUNDERSTORMS ARE POSSIBLE THROUGH 22Z OR 23Z. SOUTH WINDS SHIFT THIS EVENING...AND TIMING OF ANY WIND SHIFT MAY BE OFF AN HOUR OR TWO. GUSTS MAY BE OCCASIONAL. KEWR FCSTER COMMENTS: AMENDMENTS FOR ANY THUNDERSTORMS ARE POSSIBLE THROUGH 22Z OR 23Z. SEA BREEZE SE FLOW WILL SHIFT THIS EVENING AND LIGHTEN. KTEB FCSTER COMMENTS: AMENDMENTS FOR ANY THUNDERSTORMS ARE POSSIBLE THROUGH 22Z. KHPN FCSTER COMMENTS: AMENDMENTS FOR ANY THUNDERSTORMS ARE POSSIBLE THROUGH 22Z. KISP FCSTER COMMENTS: BECOMING VFR. POSSIBLE LATE DAY SHOWER. .OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY... .FRI AFTERNOON-FRI EVENING...VFR. SE WINDS. .FRI NIGHT-SAT...MORNING MVFR OR LOWER POSSIBLE...THEN VFR. INCREASING SLY FLOW. .SAT NIGHT-MON...MVFR OR LOWER IN SHOWERS/TSTMS AT TIMES. SHIFTING WINDS TO THE E/NE. .MON...POSSIBLE IMPROVEMENT TO VFR IF SHOWERS/TSTMS MOVE TO THE SOUTH. E/NE FLOW. .MON NIGHT-TUE...MAINLY VFR WITH LINGERING SHOWERS POSSIBLE. && .MARINE...
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WITH A WEAKENING COLD FRONT MOVING IN AND A WEAK PRESSURE GRADIENT SHIFTING IN WITH A TROUGH...NOT EXPECTING WINDS TO PICK UP TOO MUCH INTO EARLY EVENING. THERE COULD BE A GUST OR TWO UP TO 25 KT...BUT THINKING THIS LIKELY WOULD NOT BE A WIDESPREAD CASE. SEAS LIKELY REMAIN JUST BELOW 5 FT BEFORE SUBSIDING OVERNIGHT. SUB-SCA CONDS THEN CONTINUE INTO FRIDAY AND FRIDAY NIGHT WITH WINDS REMAINING BELOW 15 KT. SOUTHERLY FLOW INCREASES SATURDAY AND SATURDAY NIGHT WITH HIGH PRESSURE MOVING FARTHER OFFSHORE. THE SOUTHERLY FETCH WILL BUILD SEAS ON THE OCEAN TO 5 FT SATURDAY LATE IN THE DAY. THE OCEAN SEAS REMAIN WITHIN SCA RANGE...MAINLY 5 TO 7 FT...FOR THE REST OF THE MARINE FORECAST PERIOD WITH WINDS BEING MORE MARGINAL EXCEPT FOR WESTERN OCEAN SATURDAY WITH AMBROSE JET LIKELY ENHANCING WINDS AND THEN AGAIN ON MONDAY...WHEN GUSTS WILL REACH NEAR 25 KT. THE FLOW SWITCHES TO MORE EASTERLY SUNDAY INTO EARLY NEXT WEEK WHICH WILL HELP KEEP SWELLS AND HIGHER SEAS WITHIN THE OCEAN FORECAST WATERS.
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&& .HYDROLOGY... TSTMS INTO EARLY THIS EVENING COULD PRODUCE LOCALLY HEAVY RAINFALL. FLASH FLOODING IS NOT OUT OF THE QUESTION...BUT DOES NOT LOOK TO BE WIDESPREAD. MOST LOCATIONS THAT RECEIVE RAINFALL WITH THESE STORMS WOULD PROBABLY SEE MINOR URBANIZED/SMALL STREAM FLOODING AT MOST. THERE WILL BE POTENTIAL FOR AN EXTENDED SIGNIFICANT WIDESPREAD RAINFALL...MAINLY SUNDAY THROUGH MONDAY WITH A COLD FRONT STALLING NEAR THE REGION. IT IS DIFFICULT TO SPECIFY EXACT RAINFALL AMOUNTS...BUT THERE WILL BE POTENTIAL FOR HEAVY RAINFALL ESPECIALLY SUNDAY AND SUNDAY NIGHT INTO EARLY MONDAY MORNING WHEN PRECIPITABLE WATERS REACH 1.5 TO 1.75 INCHES. ANY SHOWERS AND THUNDERSTORMS COULD PRODUCE LOCALLY HEAVY RAINFALL AND THEREFORE AT LEAST MINOR FLOODING OF URBAN/POOR DRAINAGE AREAS WILL BE A POSSIBILITY. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...JC/JM NEAR TERM...JC/JM SHORT TERM...JC LONG TERM...JM AVIATION...PW MARINE...JC/JM HYDROLOGY...JC/JM

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