Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 121946 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 346 PM EDT SAT JUL 12 2014 .SYNOPSIS...
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HIGH PRESSURE WILL CONTINUE MOVING OFFSHORE THROUGH SUNDAY. A COLD FRONT WILL SLOWLY APPROACH THE REGION FROM THE WEST ON SUNDAY...THEN STALL NEAR THE REGION THROUGH WEDNESDAY. HIGH PRESSURE RETURNS FOR THE END OF THE WEEK.
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&& .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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SURFACE TROUGH JUST WEST OF THE REGION MAY STILL DEVELOP AN ISOLATED SHOWER OR THUNDERSTORM ACROSS ORANGE AND WESTERN PASSAIC COUNTIES LATE THIS AFTERNOON. SLIGHT CHANCE REMAINS UNTIL EARLY EVENING. OTHERWISE...CONTINUED DRY FORECAST TONIGHT. SURFACE HIGH PRESSURE WILL CONTINUE SHIFTING OFFSHORE DURING THIS PERIOD. ALOFT...HEIGHTS WILL SLOWLY FALL IN RESPONSE TO DEVELOPING UPPER LEVEL TROUGH ACROSS THE GREAT LAKES. PATCHY FOG IS POSSIBLE TOWARDS DAYBREAK AS LOW LEVEL MOISTURE INCREASES. LOW TEMPERATURES NEAR NORMAL IN THE 60S ARE FORECAST.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
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SOUTHERLY FLOW INCREASES WITH TIGHTENING GRADIENT BETWEEN HIGH PRESSURE OFFSHORE AND LOW PRESSURE ACROSS SOUTHEASTERN CANADA. THIS BRINGS A WARM AND HUMID AIR MASS TO THE REGION. IT WILL ALSO BECOME QUITE BREEZY...ESPECIALLY NEAR THE COAST. LOW LEVEL MOISTURE WILL BE ON THE RISE AS DEW POINTS REACH THE UPPER 60S AND POSSIBLY LOWER 70S BY LATE AFTERNOON. DAYTIME HEATING ALONG WITH PREFRONTAL TROUGH DEVELOPMENT WEST OF THE CITY SHOULD TRIGGER AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. UPPER LEVEL HEIGHTS SLOWLY FALL...BUT THE MAIN CLOSED LOW WILL STILL BE A SIGNIFICANT DISTANCE AWAY FROM THE AREA. CAPE VALUES INCREASE TO AROUND 1000-1200 J/KG AND 0-6 KM BULK SHEAR INCREASES TO 25-30 KT ON SUNDAY...MAINLY FROM THE CITY NORTH AND WEST. PWATS ALSO SURGE TO AROUND 1.9 INCHES BY SUNDAY EVENING. WITH THESE INGREDIENTS...HEAVY RAINFALL IS POSSIBLE IN ANY STORM. AN ISOLATED STRONG TO SEVERE STORM CANNOT BE RULED OUT. DAMAGING WIND GUSTS WOULD BE THE MAIN THREAT IF A STORM DOES BECOME SEVERE. SHOWER AND STORM ACTIVITY WILL WEAKEN SOME WITH LOSS OF DAYTIME HEATING IN THE EVENING AND OVERNIGHT. WITH SURFACE TROUGH LINGERING ACROSS THE REGION AND CONTINUED WARM ADVECTION...SHOWERS AND STORMS WITH HEAVY RAINFALL REMAIN POSSIBLE. HIGH TEMPERATURES ON SUNDAY WILL BE NEAR NORMAL IN THE LOW TO MIDDLE 80S. LOCATIONS NEAR THE COAST MAY STAY IN THE UPPER 70S DUE TO ONSHORE FLOW. WARM AND MUGGY SUNDAY NIGHT WITH TEMPERATURES IN THE LOWER 70S.
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&& .LONG TERM /MONDAY THROUGH SATURDAY/...
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THE LONG TERM FORECAST STARTS OFF WITH UNSETTLED WEATHER FOR THE MONDAY THROUGH WEDNESDAY TIME FRAME THANKS TO A STRONG COLD FRONT SLOWLY APPROACHING FROM THE WEST. ON MONDAY...THE MAIN COLD FRONT REMAINS OVER THE MIDWEST WITH THE MAIN UPPER LOW AS A WEAKER FRONT DEVELOPS IN CENTRAL PA. RAIN CHANCES INCREASE QUICKLY ON MONDAY AND SHOWERS AND THUNDERSTORMS ARE LIKELY BY MONDAY AFTERNOON. STRONG THUNDERSTORMS AND FLOODING ARE POSSIBLE ON MONDAY. PW VALUES OVER 2 INCHES AND DEW POINTS IN THE LOWER 70S WILL BE IN PLACE ALONG WITH THE STALLING FRONT CREATING TRAINING OF CELLS SO WILL CONTINUE HEAVY RAIN WORDING. SEE HYDROLOGY SECTION FOR ADDITIONAL DETAILS. AS WELL...MU CAPE VALUES INCREASE TO OVER 2000 J/KG FOR AREAS WEST OF NYC MON AFTERNOON AND SHEAR VALUES WILL BE GRADUALLY INCREASING. CANNOT RULE OUT A FEW STRONG TO SEVERE STORMS. HEAVY RAIN AND LIKELY POPS CONTINUE THROUGH TUE MORNING. AREAS EAST OF NYC...WITH THE STABILIZING SOUTHERLY FLOW...THERE WILL BE LESS OF A CHANCE OF SEVERE STORMS. STARTING TUE MORNING...CONFIDENCE DROPS IN POP AMOUNTS FOR TUESDAY. LARGE DISCREPANCY IN MODEL GUIDANCE WITH THE ONE EXTREME...THE NAM..WITH NO PRECIP WEST OF NYC AFTER 12Z. ON THE OTHER SIDE...THE 12/12Z ECMWF IS THE SLOWEST WITH PRECIP OVER THE LONGEST PERIOD. THE ECMWF BRINGS THE MAIN COLD FRONT THROUGH LATE WED WHILE GFS/GEFS/CMC HAS IT THROUGH BY WED MORNING. WILL KEEP CHANCE POPS THROUGH WED MORNING TO ACCOUNT FOR THIS BUT TRENDS WILL HAVE TO BE MONITORED. CANNOT COMPLETELY RULE OUT THIS SOLUTION. IF THIS SOLUTION IS CORRECT...TUES WILL BE ANOTHER DAY OF HEAVY RAIN AND POTENTIALLY STRONG STORMS WITH 0-6KM SHEAR OF 45-50 KT BUT LESS CAPE THAN MONDAY. BEHIND THE FRONT...A DEEP UPPER TROUGH WILL CONTINUE ITS WAY EAST WITH HIGH PRESSURE BUILDING IN AT THE SURFACE. ZONAL FLOW RETURNS FOR THE END OF THE WEEK. HIGHS MON-TUE WILL BE IN THE LOWER TO UPPER 80S WITH LOWS REMAINING IN THE LOWER 70S. TEMPERATURES THU-SAT WILL BE GENERALLY NEAR TO SLIGHTLY BELOW SEASONAL NORMALS.
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&& .AVIATION /20Z SATURDAY THROUGH THURSDAY/...
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HIGH PRESSURE WILL REMAIN OFFSHORE THROUGH TONIGHT...THEN MOVE FARTHER EAST ON SUNDAY AS A COLD FRONT APPROACHES. SOUTH TO SOUTHWEST WINDS HAVE INCREASE THIS AFTERNOON. SPEEDS ARE AROUND 10-12 KT. SEABREEZES WILL ENHANCE THE WINDS ALONG THE COAST...WITH SPEEDS AS HIGH AS 15 KT. MVFR FOG DEVELOPMENT MORE LIKELY TONIGHT WITH A LIGHT ONSHORE FLOW. FEW TO SCATTERED 005 KFT TO 010 KFT CLOUDS POSSIBLE. LOW CHANCE OF IFR CEILINGS ALONG THE COAST AFTER 09Z. ALL TERMINALS SHOULD RETURN TO VFR BY 14Z...HOWEVER CLOUDS WILL GRADUALLY INCREASE THROUGH THE DAY. FOR THE 30 HOUR TAFS WEST OF NYC...HAVE INCLUDED A PROB30 GROUP FOR THUNDER LATE IN THE DAY. .OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY... .SUNDAY AFTERNOON-WEDNESDAY...SCATTERED TO NUMEROUS SHRA/TSTMS. STRONGER TSTMS DURING THIS TIME FRAME COULD PRODUCE PERIODS OF MVFR OR LOWER CONDITIONS...LOCALLY HEAVY RAINFALL...AND GUSTY WINDS. CONDITIONS IMPROVE LATE WEDNESDAY. .THURSDAY...VFR.
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&& .MARINE...
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TRANQUIL CONDITIONS ON THE WATERS THROUGH EARLY SUNDAY MORNING. SOUTHERLY FLOW INCREASES ON SUNDAY AND WINDS INCREASE TO SCA LEVELS WITH WINDS IN THE AFTERNOON AND EVENING ON THE OCEAN WATERS. HAVE ISSUED A SCA FOR THE HARBOR AND OCEAN WATERS STARTING AT 16Z. SEAS WILL ALSO BE RISING TO AROUND 5 FT SUNDAY NIGHT OVER THE OCEAN WITH THE INCREASED SOUTHERLY FLOW. THE SCA CURRENTLY GOES TO 04Z MONDAY ON THE HARBOR AND 10Z MONDAY ON THE OCEAN WATERS. SOUTHERLY FLOW REMAINS ELEVATED ON MONDAY WITH OCEAN SEAS RISING TO 5-7 FEET BY MONDAY EVENING AND WIND GUSTS OF 20-25KT. THIS WILL CONTINUE ON TUESDAY WITH WINDS SLOWLY DIMINISHING TUESDAY EVENING. SEAS WILL BE SLOW TO DIMINISH WITH 5 FT SEAS POSSIBLE THROUGH WEDNESDAY EVENING. SUB SCA CRITERIA EXPECTED ON THURSDAY. .
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&& .HYDROLOGY...
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NO SIGNIFICANT PRECIPITATION IS FORECAST THROUGH SUNDAY MORNING. THERE IS THE POTENTIAL FOR SIGNIFICANT RAINFALL FROM LATE SUNDAY INTO EARLY WEDNESDAY. AT THIS TIME THERE IS TOO MUCH UNCERTAINTY TO SPECIFY EXACT AMOUNTS OR SPECIFIC THREATS...OTHER THAN TO NOTE FLOODING IS POSSIBLE IN AREAS THAT EXPERIENCE ROUNDS OF LOCALLY HEAVY RAINFALL.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY FROM NOON SUNDAY TO 6 AM EDT MONDAY FOR ANZ350-353-355. SMALL CRAFT ADVISORY FROM NOON SUNDAY TO MIDNIGHT EDT SUNDAY NIGHT FOR ANZ338.
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&& $$ SYNOPSIS...LN/DS NEAR TERM...DS SHORT TERM...DS LONG TERM...LN AVIATION...BC MARINE...LN/DS/MET HYDROLOGY...LN/DS

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