Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 141457 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1057 AM EDT MON APR 14 2014 .SYNOPSIS... OFFSHORE HIGH PRESSURE WILL EVENTUALLY GIVE WAY TO AN APPROACHING COLD FRONT FROM THE WEST ON TUESDAY. THE FRONT MOVES ACROSS TUESDAY EVENING AND SOUTHEAST OF LONG ISLAND OVERNIGHT TUESDAY. HIGH PRESSURE BUILDS IN FROM THE WEST WEDNESDAY...THEN REMAINS NORTH OF THE REGION WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. THE HIGH WEAKENS AND MOVES EAST FRIDAY...ALLOWING A LOW PRESSURE SYSTEM TO APPROACH FROM THE SOUTHWEST THIS WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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FORECAST MAINLY ON TRACK...WITH MAIN ADJUSTMENT TO TEMPS TRENDS. GUSTY SOUTHERLY FLOW TODAY...WITH 15 TO 25 MPH SUSTAINED AND GUSTS 30 TO 40 MPH THIS AFTERNOON. SCT INSTABILITY CU ACROSS INTERIOR LATE THIS MORNING AFTERNOON. STRATUS DEVELOPMENT POSSIBLE THIS AFTERNOON ACROSS SE COASTAL AREAS...WITH INCREASING LIKELIHOOD TOWARDS EVENING. INCREASING HIGH CLOUDS THIS AFTERNOON. HIGHS WELL INTO THE 70S TO A FEW 80S WEST OF THE HUDSON RIVER...WHILE TEMPS ALONG IMMEDIATE SOUTH COASTAL AREAS WILL LIKELY HOLD IN THE LOWER 60S. OTHERWISE...OFFSHORE HIGH PRESSURE AND INCREASING MERIDIONAL FLOW FROM APPROACHING MID AND UPPER LEVEL TROUGH WILL CONTINUE THE WARM AND MOIST AIR ADVECTION.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... TONIGHT THROUGH TUESDAY NIGHT...MODELS HAVE BEEN CONSISTENT OVER LAST FEW DAYS SHOWING A STRENGTHENING COLD FRONT APPROACHING AND MOVING ACROSS THE REGION TUESDAY EVENING. LAYER PW HAS ALSO BEEN CONSISTENT...STILL CONVEYING 1.3 TO 1.5 INCHES...ABOUT 2 STANDARD DEVIATIONS ABOVE NORMAL FOR THIS TIME OF YEAR...ADDING TO THE POTENTIAL FOR HEAVY RAIN. THIS GOES ALONG WITH THE INCREASING MERIDIONAL FLOW FROM THE APPROACHING TROUGH AND UPPER LEVEL JET ORIENTED SOUTHWEST TO NORTHEAST...TAPPING INTO GULF MOISTURE. THIS INCREASING MOISTURE ADVECTION IS REFLECTED AS WELL WITH THE LOW LEVELS...WHICH WILL HAVE AN INCREASE IN STRATUS AND/OR FOG TONIGHT INTO TUESDAY MORNING. THE FOG COULD POTENTIALLY BE DENSE AS DEWPOINTS INCREASE AND SEA SURFACE TEMPERATURES WILL STILL BE RELATIVELY COOL. THE STRENGTH OF THE PARENT LOW IS NEARLY THE SAME COMPARED TO PREVIOUS RUNS WITH NEARLY THE SAME MAGNITUDE OF LOW LEVEL JET. NAM SHOWS 70-80 KT AROUND 900MB TUESDAY AFTERNOON AND EVENING WHILE GFS SHOWS 60-70 KT. INVERSION WILL LIMIT GUSTS BUT MODERATE TO HEAVY RAIN MAY HAVE ENOUGH DOWNWARD MOMENTUM TO OVERCOME THE INVERSION AND BRING A FRACTION OF THIS LOW LEVEL JET TO THE SURFACE. THERE IS A POTENTIAL HERE FOR HIGHEST GUSTS IN THE 40-55 MPH RANGE WITH HEAVY RAIN WHICH WILL BE MORE PERIODIC IN FREQUENCY. FOR EXAMPLE...THIS COULD BE OBSERVED WITHIN HEAVIER CELLS ASSOCIATED WITH A SQUALL LINE JUST AHEAD OF THE COLD FRONT AS IT MOVES THROUGH. MESOSCALE MODELS ARE POINTING TO THIS SORT OF STRUCTURE TO RAINFALL BETWEEN MID AFTERNOON TUESDAY AND EARLY TUESDAY EVENING. PRECIP BEHIND THE COLD FRONT CONTINUES A TREND TO END AS A SLEET/SNOW MIX AS COLDER AIR MOVES IN...MAINLY IN THE BOUNDARY LAYER. PART OF THE ATMOSPHERIC COLUMN BETWEEN 700 AND 850 MB MAY STILL BE A LITTLE ABOVE FREEZING...HENCE THE POTENTIAL FOR SLEET. GUSTS WILL BE MORE FREQUENT TOO WITH THE COLD AIR ADVECTION INCREASING THE MIXING LENGTH TUESDAY NIGHT WITH THE NORTHWEST FLOW...ALTHOUGH THE GUSTS WILL PROBABLY BE MORE BETWEEN 35-45 MPH WITH THE DECREASING BOUNDARY LAYER WINDS AS THE LOW LEVEL JET WILL HAVE MOVED WELL SOUTHEAST OF THE REGION WITH THE FRONT. IN SUMMARY...THERE WILL STILL BE A WIDESPREAD RAIN EVENT WITH THE POTENTIAL FOR HEAVY RAIN AT TIMES ALONG WITH A CHANCE OF GUSTY WINDS AT TIMES WITH THE HEAVIER RAIN AND MORE FREQUENT WITH THE COLD AIR ADVECTION LATER TUESDAY NIGHT. LATE TUESDAY NIGHT...ENOUGH COLD AIR COULD MOVE IN FOR LEFTOVER SNOW SHOWERS AND/OR SLEET WITH LIGHT ACCUMULATIONS POSSIBLE NORTH AND WEST OF NEW YORK CITY. LOW TEMPERATURES WILL BE NEAR OR BELOW FREEZING LATE TUESDAY NIGHT INTO VERY EARLY WEDNESDAY MORNING. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... THE COLD FRONT IS NOW EXPECTED TO BE EAST OF THE REGION BY 12Z WEDNESDAY WITH A FEW LINGERING SHOWERS ACROSS THE TWIN FORKS AND SOUTHEASTERN CONNECTICUT POSSIBLE IN THE EARLY PERIOD OF WEDNESDAY MORNING. COLDER AIR LAGS BEHIND THE FRONT AND KEPT ALL LIQUID PRECIPITATION. WITH COLD ADVECTION BEHIND THE FRONT AND LOW LEVEL WIND AROUND 40 KT...GUSTY NORTHWESTERLY WIND WILL USHER IN THE COLD AIRMASS. RIDGE BUILDS QUICKLY BEHIND THE FRONT AND COLD ADVECTION WEAKENS BY 18Z SO WINDS AND GUSTS WILL DIMINISH. HIGHS ACROSS THE AREA EXPECTED TO PEAK IN THE MID AND UPPER 40S...MAYBE AROUND 50 IN THE NYC METRO. THIS IS AROUND 10 DEGREES BELOW NORMAL. RIDGE BUILDS NORTH AND EAST WEDNESDAY NIGHT AND WIND BECOMES LIGHT FROM THE NORTHEAST. WITH RELATIVELY LIGHT WIND AND THE CHILLY AIRMASS IN PLACE HAVE INCLUDED THE MENTION OF PATCHY FROST FOR WEDNESDAY NIGHT AS THE SPRING FROST/FREEZE PROGRAM BEGINS ACROSS PORTIONS OF THE LOWER HUDSON VALLEY AND NORTHEASTERN NEW JERSEY. TEMPERATURES WILL FALL BELOW FREEZING ACROSS PORTIONS OF THE LOWER HUDSON VALLEY...WITH LOWS NEAR FREEZING ACROSS NORTHEASTERN NEW JERSEY AND THE SOUTHERN LOWER HUDSON VALLEY. AT THIS TIME LOW TEMPERATURE RECORDS ARE NOT EXPECTED TO BE BROKEN. HIGH PRESSURE REMAINS TO THE NORTH AND EAST OF THE REGION THURSDAY INTO THE WEEKEND AS LOW PRESSURE APPROACHES FROM THE SOUTHWEST. AN EASTERLY FLOW AROUND THE HIGH WILL KEEP TEMPERATURE BELOW SEASONAL NORMALS THROUGH THE PERIOD. UPPER TROUGH APPROACHING FROM THE WEST FOR THE WEEKEND AND PHASES WITH A WEAK SOUTHERN STREAM TROUGH WHILE ONE SURFACE LOW PRESSURE APPROACHES FROM THE WEST AND ANOTHER MOVES THROUGH THE WESTERN ATLANTIC. SOME UNCERTAINTY WITH TIMING AND AREAL EXTENT OF THE PRECIPITATION FOR THE UPCOMING WEEKEND. && .AVIATION /14Z MONDAY THROUGH FRIDAY/...
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VFR WITH A STRONG SLY FLOW TODAY...G25-30 KY BY AFT. KJFK MAY JUST STAY WITH A GRADUALLY INCREASING SUSTAINED WIND WITH ONLY OCCASIONAL GUSTS. FORECAST UNCERTAINTY THIS AFT LIES IN DEVELOPMENT OF STRATUS IN THE NEAR SHORE WATERS AND ITS MOVEMENT INLAND. LATEST GUIDANCE KEEP THE STRATUS TO THE EAST OF THE AREA THIS AFT AND THEN BRINGS IT IN TONIGHT. INCREASING CONFIDENCE OF DIMINISHING CONDITIONS THIS EVENING WITH LOW PRESSURE APPROACHING. GENERAL TIMING OF DIMINISHING CONDITIONS 01-03Z. LIGHT RAIN BEGINS TO MOVE IN AFTER MIDNIGHT WITH CIGS/VIS LOWERING THROUGHOUT THE NIGHT TO IFR OR LOWER CONDITIONS. TIMING OF HEAVIER PCPN LOOKS TO BE AFTR 12Z TUES. SLY FLOW FOR THE PERIOD...INCREASING DURING THE DAY. GUSTS BEGIN MIXING IN BETWEEN 13-16Z...WITH STRONGEST GUSTS 25-30 KTS AFTR 18Z. LLWS PSBL AFTR 00Z...WITH 50 KT WINDS AROUND 2KFT. HIGHER CONFIDENCE LLWS BECOMES AN ISSUE AFTR 06Z...WITH WINDS INCREASING 50-60 KTS AT 2KFT. 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) KEWR FCSTER COMMENTS: OCCASIONAL GUSTS 30-35 KT THIS AFT. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KJFK FCSTER COMMENTS: SUSTAINED 20-25 KT THIS AFT...BUT AN OCCASIONAL GUSTS UP TO 30 KT POSSIBLE.. KLGA FCSTER COMMENTS: 170-190 DIRECTION THIS MORNING...VEERING TOWARD 190 THIS AFT, KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KISP FCSTER COMMENTS: WATCHING POTENTIAL DEVELOPMENT OF OFFSHORE STRATUS THIS AFT. .OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY... .TUE-TUE NIGHT...IFR LIKELY WITH MOD TO HEAVY RAIN AND FOG. LLWS PSBL MORNING/AFTN 50-60 KTS 2KFT. GUSTY NW-N WINDS AFTER COLD FROPA TUE NIGHT. .WED-FRI...VFR.
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&& .MARINE...
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PATCHY FOG ON THE OCEAN WATERS WILL LINGER AND EVENTUALLY EXPAND WITH CONTINUED SOUTHERLY FLOW LATER THIS AFTERNOON. FOG ON THE WATERS CONTINUES TONIGHT INTO TUESDAY...WHICH COULD BE DENSE. NEAR SHORE GUSTS OF 25 TO 30 KT LATE THIS MORNING THROUGH THIS AFTERNOON. OCCASIONAL 35 KT GUST POSSIBLE ACROSS WESTERN OCEAN WATERS...HARBOR...AND WESTERN LI SOUND LATE AFT/EARLY EVE WITH COASTAL JET. SCA CONDITIONS ON THE OCEAN THROUGH TONIGHT WITH GALES POSSIBLE TUESDAY AND TUESDAY NIGHT. THE RELATIVELY HIGHER PROBABILITY OF GALES WILL BE TUESDAY NIGHT WHEN ALL WATERS WILL HAVE A DECENT CHANCE OF GALES WITH THE COLD AIR ADVECTION BEHIND THE COLD FRONT AND INCREASED MIXING LENGTH. ON GOING GALE FORCE GUSTS ACROSS THE FORECAST WATERS EARLY WEDNESDAY WILL DIMINISH AS HIGH PRESSURE BUILDS TOWARD THE WATERS DURING THE DAY. BY LATE AFTERNOON WIND GUSTS ARE EXPECTED TO HAVE DIMINISHED BELOW SMALL CRAFT LEVELS ACROSS ALL THE WATERS. THEN WITH HIGH PRESSURE BUILDING TO THE NORTH AND EAST OF THE WATERS LATE WEDNESDAY NIGHT INTO THURSDAY AS A WAVE OF LOW PRESSURE MOVES THROUGH THE WESTERN ATLANTIC THERE COULD BE A PERIOD OF SMALL CRAFT GUSTS ON THE OCEAN WATERS. SEAS ON THE OCEAN WATERS WILL LIKELY REMAIN AT SMALL CRAFT LEVELS WEDNESDAY THROUGH FRIDAY NIGHT WITH AN EASTERLY FLOW WITH HIGH PRESSURE TO THE NORTH AND A STALLED FRONTAL BOUNDARY ACROSS THE NORTHERN ATLANTIC.
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&& .HYDROLOGY...
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QPF OF 1 TO 2 INCHES...NEARLY ALL RAIN...EXPECTED FROM LATE MON NIGHT INTO TUE NIGHT...WITH WETTER GUIDANCE STILL SIGNALING POTENTIAL FOR HIGHER END LOCAL AMTS OF 2-3 INCHES. POTENTIAL FOR MINOR FLOODING OF URBAN/POOR DRAINAGE AREAS AND FLASHY SMALL STREAMS. DRY WEDNESDAY THROUGH FRIDAY...THEN NO SIGNIFICANT PRECIPITATION THROUGH THE WEEKEND.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...GALE WATCH FROM TUESDAY EVENING THROUGH LATE TUESDAY NIGHT FOR ANZ330-335-338-340-345. SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR ANZ330- 335-338-340-345. GALE WATCH FROM TUESDAY MORNING THROUGH LATE TUESDAY NIGHT FOR ANZ350-353-355. SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR ANZ350-353-355. && $$ SYNOPSIS...JM/MET NEAR TERM...JM/NV SHORT TERM...JM LONG TERM...MET AVIATION...SEARS/DW MARINE...JM/MET HYDROLOGY...JM/MET

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