Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 020841 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 441 AM EDT SAT MAY 2 2015 .SYNOPSIS... HIGH PRESSURE BUILDS INTO THE REGION TODAY AND THEN OFF THE MIDDLE ATLANTIC COAST LATE SUNDAY INTO MONDAY. A COLD FRONT APPROACHES FROM THE GREAT LAKES MONDAY NIGHT. A COLD FRONT PUSHES TO THE SOUTH ON TUESDAY...THEN STALLS NEAR THE AREA INTO WEDNESDAY. HIGH PRESSURE THEN BUILDS DOWN FROM CANADA THROUGH THURSDAY NIGHT. THE HIGH RETREATS TO THE NORTHEAST ON FRIDAY AS A COLD FRONT APPROACHES FROM THE NORTHWEST. && .NEAR TERM /THROUGH TONIGHT/...
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HIGH PRESSURE WILL BUILD INTO THE REGION TODAY AS LOW PRESSURE MOVES SLOWLY AWAY FROM THE MIDDLE ATLANTIC COAST. A WEAK 500 MB SHORTWAVE IS FORECAST TO MOVE THROUGH DURING THE AFTERNOON. THIS SHORTWAVE COMBINED WITH DAYTIME HEATING DEVELOPING A THERMAL TROUGH OVER NE NJ AND THE LOWER HUDSON VALLEY COULD INITIATE A SHOWER IN THE AFTERNOON. OTHERWISE...PARTLY CLOUDY SKY CONDITIONS ARE FORECAST. HAVE SIDED WITH THE WARMER MAV GUIDANCE FOR TEMPERATURES...WITH HIGHS REACHING THE UPPER 60S AND LOWER 70S FROM THE CITY NORTH AND WEST. HIGHS SHOULD REACH THE LOWER AND MIDDLE 60S CLOSER TO THE COAST DESPITE A LIGHT ONSHORE FLOW. WITH LOSS OF DAYTIME HEATING AND SHORTWAVE RIDING BUILDING ALOFT TONIGHT...SKY CONDITIONS WILL BECOME MOSTLY CLEAR. LOW TEMPERATURES WILL BE IN THE UPPER 40S AND LOWER 50S IN THE NYC METRO...WITH LOW TO MIDDLE 40S ELSEWHERE.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... HEIGHTS ALOFT WILL CONTINUE TO RISE ON SUNDAY. SURFACE HIGH PRESSURE WILL SHIFT SOUTH OF THE AREA AS WELL. THIS WILL LEAD TO A CONTINUED WARMING TREND. TEMPERATURES WILL RISE TO ABOVE NORMAL LEVELS IN THE LOWER AND MIDDLE 70S. AFTERNOON SEA BREEZES WILL LIKELY PREVENT TEMPERATURES NEAR THE COAST FROM RISING ABOVE THE LOWER 70S. AS WAS THE CASE ON SATURDAY...DAYTIME HEATING WILL DEVELOP A THERMAL TROUGH ACROSS NE NJ AND THE LOWER HUDSON VALLEY. MODEL GUIDANCE ALSO INDICATES WEAK VORTICITY/SHORTWAVE ENERGY MOVING OVER THE AREA IN THE AFTERNOON. THESE FEATURES COULD INITIATE A SHOWER...MAINLY OVER THE INTERIOR. HAVE SLIGHT CHANCE POPS DURING THE AFTERNOON HOURS ON SUNDAY. HIGH PRESSURE MOVES OFF THE MIDDLE ATLANTIC COAST SUNDAY NIGHT INTO MONDAY AS HEIGHTS CONTINUE TO RISE ALOFT. EVEN WARMER AIR IS LIKELY TO MOVE INTO THE AREA ON MONDAY. 850 MB TEMPERATURES SHOULD RISE TO BETWEEN 10 AND 12C. GOOD MIXING AND AND MOSTLY SUNNY SKY CONDITIONS ALLOW TEMPERATURES TO RISE INTO THE UPPER 70S AND LOWER 80S CLOSER TO THE COAST...AFTERNOON SEA BREEZES DEVELOP CAPPING HIGH TEMPERATURES IN THE MIDDLE 70S. NO SHOWERS ARE EXPECTED MONDAY WITH DEEP UPPER LEVEL RIDGING OVERHEAD. RIDGING ALOFT MOVES EAST OF THE AREA MONDAY NIGHT ALLOWING A COLD FRONT TO APPROACH FROM THE GREAT LAKES REGION. A SHOWER CANNOT BE RULED OUT ACROSS THE FAR NW INTERIOR TOWARDS DAY BREAK TUESDAY MORNING. && .LONG TERM /TUESDAY THROUGH FRIDAY/... THE LONG TERM STARTS WITH THE REGION IN BETWEEN RIDGING TO THE SOUTH AND AN UPPER LOW TO THE NORTH...THIS SPLIT FLOW REGIME FLIPS TOWARDS THE END OF THE WORK WEEK...WITH RIDGING BUILDING INTO THE GREAT LAKES AND NORTHEAST AND TROUGHING OVER THE SOUTHEASTERN U.S. IN TERMS OF SENSIBLE WEATHER...COULD SEE SOME SHOWERS AND MAYBE A THUNDERSTORM TUESDAY WITH THE PASSAGE OF A COLD FRONT. GFS IS MOST BULLISH WITH PRECIPITATION WITH THE FRONT...ECMWF MUCH LESS SO. THIS DIFFERENCE IS MOST NOTABLE IN THE RISK OF THUNDER...WITH THE ECMWF INDICATING MUCH LESS INSTABILITY OVER THE REGION...BOTH AT THE SURFACE AND ALOFT THAN THE GFS. GIVEN UNCERTAINTY HAVE KEPT POPS AT CHANCE FOR NOW TUESDAY AND TUESDAY NIGHT AND HAVE REFRAINED FROM PUTTING THUNDERSTORMS IN THE FORECAST AT THIS TIME. THIS FRONT THEN STALLS OUT TO THE SOUTH INTO THE MIDDLE OF THE WEEK. THE QUESTION IS HOW FAR SOUTH/HOW QUICKLY DOES IT SINK TO THE S. THE 00Z ECMWF IS FAIRLY SIMILAR TO THE GFS AND CMC IN SUGGESTING THE FRONT WILL BE CLOSE ENOUGH TUESDAY NIGHT/WEDNESDAY MORNING FOR A PASSING 700-500 HPA SHORTWAVE TO ACT ON IT. THIS WARRANTS CHANCE POPS TUESDAY NIGHT AND SLIGHT CHANCE POPS WEDNESDAY MORNING. SUBSIDENCE AHEAD OF THE BUILDING RIDGE SHOULD KEEP THINGS DRY FROM WEDNESDAY AFTERNOON THROUGH AT LEAST FRIDAY MORNING. FOR NOW THOUGH DO BRING IN SLIGHT CHANCE POPS FRIDAY AFTERNOON OVER FAR WESTERN ZONES AHEAD OF A SLOW MOVING COLD FRONT. FOR TEMPERATURES TUESDAY-FRIDAY USED A BLEND OF MEX/EKD/ECE/ECM/WPC GUIDANCE...WITH TEMPERATURES RUNNING ABOVE NORMAL THROUGH THE PERIOD. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
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A WEAK...BROAD TROUGH OF LOW PRESSURE REMAINS OVER THE AREA INTO TONIGHT. VFR THRU THE TAF PERIOD. 6-7 THOUSAND FT CEILING AT WESTERN TERMINALS SHOULD LAST THROUGH 10-12Z - LIFTING FROM E TO W. LIGHT AND VARIABLE WINDS THROUGH AT LEAST 13Z. NE FLOW OFF THE SOUND DEVELOPS AT KLGA AROUND 14Z. A SE FLOW SETS UP AT KJFK AND KGON AROUND 14Z AND KEWR AROUND 16Z. KSWF SHOULD HAVE N WINDS DEVELOP AROUND 16Z. SEABREEZE DEVELOPS AT ALL BUT KSWF FROM LATE MORNING INTO LATE AFTERNOON STARTING ALONG SW CT COAST FIRST. WINDS UNDER 10 KT EXCEPT AROUND 10KT WITH SEABREEZE AT KJFK/KBDR/KGON/KISP TODAY. LIGHT AND VARIABLE WINDS AGAIN THIS EVENING. .OUTLOOK FOR 06Z SUNDAY THROUGH WEDNESDAY... .LATE SATURDAY NIGHT-MONDAY NIGHT...VFR. SW WINDS G15-20KT POSSIBLE MONDAY AFTERNOON. .TUESDAY-TUESDAY NIGHT...MVFR OR LOWER POSSIBLE WITH ANY SHRA/TSTMS. .WEDNESDAY...MOST LIKELY VFR. LOW CHANCE OF MVFR OR LOWER IN ANY LINGERING SHRA EARLY.
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&& .MARINE... WITH HIGH PRESSURE OVER THE WATERS THROUGH MONDAY...SUB SCA CONDITIONS ARE EXPECTED. THE NEXT CHANCE FOR SCA CONDITIONS IS LATE MONDAY AND MONDAY NIGHT AS WIND GUSTS INCREASE AND SEAS BUILD TO NEAR 5 FT ON THE OCEAN AHEAD OF AN APPROACHING COLD FRONT. OUTSIDE OF SEAS TO AROUND 5 FT POSSIBLY LINGERING OVER THE COASTAL OCEAN WATERS EAST OF MORICHES INLET ON TUESDAY...SUB-SMALL CRAFT CONDITIONS ARE EXPECTED OVER ALL WATERS TUESDAY AND WEDNESDAY. WINDS SHOULD GENERALLY BE 10 KT OR LESS DURING THIS TIME FRAME. && .HYDROLOGY... THERE IS THE CHANCE OF SOME RAINFALL FROM TUESDAY POSSIBLY INTO WEDNESDAY. AT THIS TIME IT APPEARS THAT MOST AREAS SHOULD RECEIVE LESS THAN 1/2 INCH...THOUGH GIVEN THE EXPECTED CONVECTIVE NATURE OF THE PRECIPITATION LOCALLY HIGHER AMOUNTS ARE POSSIBLE. GIVEN THE UNCERTAINTY...IT IS TO EARLY TO SPECIFY ANY POSSIBLE IMPACTS AT THIS TIME. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...DS/MALOIT NEAR TERM...DS SHORT TERM...DS LONG TERM...MALOIT AVIATION...MALOIT MARINE...DS/MALOIT HYDROLOGY...DS/MALOIT

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