Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 200845 AFDOKX Area Forecast Discussion National Weather Service New York NY 345 AM EST Mon Nov 20 2017 .SYNOPSIS...
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High pressure over the Carolinas this morning tracks rapidly east over the Atlantic tonight into Tuesday. A cold front passed on Wednesday followed by high pressure. Another cold front passes late Saturday into Sunday.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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First snow of the season at the NWS Upton office - 240 AM EST ! Moderately strong westerly flow prevails today with NCEP BUFR model soundings from HRRRx (Version 3) and RAPx (Version 4) showing good consistency with the operational GFS. Momentum transfer supports gusts of 20-25 KT this morning and then a few KT higher early this afternoon, before winds slacken by late afternoon. The light rain / snow showers dissipate by sunrise per all high resolution models. Bands of strato-cumulus are around this morning though, but expect them to dissipate to mostly sunny by noon. Used a blend of GFS/NAM and ECMWF MOS, which showed little spread, for temps.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
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The high moves off the mid Atlantic coast tonight as low level flow backs to SW. Expect a mainly clear night - seasonable. Still a fairly strong pressure gradient. Thus, do not expect much in the way of boundary layer decoupling outside of the normal locals. Used the warmer GFS MOS and warmed it manually outside the NY metro area. Even this may be too low. Tuesday sees gusty SSW flow as the cold front approaches from the west - still mostly sunny. Used the warmer ECMWF/GFS MOS resulting in about 5 degrees above normal.
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&& .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
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Best chance for rain will be east of NYC late Tuesday into Wednesday. Dry thereafter as ridge builds. A cold front passes with little fanfare Friday, then next shortwave approaches this weekend. Colder air advects in behind a front by Sunday. Minimal pops warranted next weekend with this system.
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&& .AVIATION /09Z MONDAY THROUGH FRIDAY/...
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High pressure builds to the southwest today, then to the south this evening. VFR through the TAF period. Some ceilings around 5000ft are possible mainly at city/NW terminals and Long Island/E CT terminals through around 12z. There is a very low chance for flurries at area terminals through then as well. The probability is too low to reflect in the TAFs at this time. W-WNW winds will continue through the afternoon. Gusts may end up intermittent at times during the early morning hours before increasing and becoming frequent after sunrise. Gusts should be around 25 kt during the day at most terminals. Winds will begin to back to towards the W-WSW in the evening as gusts subside. ...NY Metro Enhanced Aviation Weather Support... Detailed information...including hourly TAF wind component fcsts can be found at: http://www.weather.gov/zny/n90 KJFK TAF Comments: High confidence in winds to the left of 300 True/310 Magnetic. Timing in changes in wind speed, direction and gusts could be off +/- 1-2 hours. Isolated peak gusts could be up to 5 KT higher than gusts in TAFs. The afternoon KJFK haze potential forecast is green...which implies slant range visibility 7SM or greater outside of cloud. KLGA TAF Comments: Moderate-high confidence in winds to the left of 300 True/310 Magnetic.Timing in changes in wind speed, direction and gusts could be off +/- 1-2 hours. Isolated peak gusts could be up to 5 KT higher than gusts in TAFs. The afternoon KLGA haze potential forecast is green...which implies slant range visibility 7SM or greater outside of cloud. KEWR TAF Comments: High confidence in winds to the left of 300 True/310 Magnetic. Timing in changes in wind speed, direction and gusts could be off +/- 1-2 hours. Isolated peak gusts could be up to 5 KT higher than gusts in TAFs. The afternoon KEWR haze potential forecast is green...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Timing in changes in wind speed, direction and gusts could be off +/- 1-2 hours. Isolated peak gusts could be up to 5 KT higher than gusts in TAFs. KHPN TAF Comments: Timing in changes in wind speed, direction and gusts could be off +/- 1-2 hours. Isolated peak gusts could be up to 5 KT higher than gusts in TAFs. KISP TAF Comments: Timing in changes in wind speed, direction and gusts could be off +/- 1-2 hours. Isolated peak gusts could be up to 5 KT higher than gusts in TAFs. .OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY... .Late tonight-Tuesday evening...VFR. SW winds G20-35KT possible Tuesday afternoon/evening. Strongest gusts at eastern terminals. .Late Tuesday night-Wednesday...MVFR possible with showers. NW-N winds G20-25KT possible in the afternoon. .Wednesday night-Friday...VFR. NW-N winds G15-25KT possible Wednesday night.
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&& .MARINE...
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Gusts today to around 30 KT all waters...with an occasional gust into the lower to mid 30s. Winds subside briefly overnight, but pick right up again on Tuesday from the SSW as a cold front approaches for the west. Expect SCA all waters on Tuesday. Gales possible Tuesday night. Low pressure passes southeast of the waters Wednesday as the cold front crosses the area. NW flow Wed night back to the west and diminishes further Thursday as a ridge of high pressure builds. A cold front passes Friday, with the ridge building back yet again.
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&& .HYDROLOGY... No hydrologic problems are anticipated the next 7 days. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until midnight EST tonight for ANZ330-335- 338-340-345. Small Craft Advisory until 6 AM EST Tuesday for ANZ350-353-355.
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&& $$ SYNOPSIS...Tongue NEAR TERM...Tongue SHORT TERM...Tongue LONG TERM...24 AVIATION...Maloit MARINE...Tongue HYDROLOGY...Tongue

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