Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 201738 AFDOKX Area Forecast Discussion National Weather Service New York NY 1238 PM EST Mon Nov 20 2017 .SYNOPSIS... 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. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Forecast on track with just some minor adjustments to reflect latest observations. Otherwise, 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 early this afternoon, before winds slacken by late afternoon. Expect partly to mostly sunny skies. 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/... 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. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... NWP in good agreement at H5 through the weekend with a fairly progressive flow. The period starts with deep SW flow as an upper trough approaches from the west Tue night. There is good agreement that the best upper support passes N and W of the local area on Wed. Upper pattern then briefly flattens before a weak shortwave passes through on Thu, followed by another on Fri. Brief ridging again builds in for Fri night with yet another trough for Sun. At the sfc, return flow across the area Tue night will result in steady to slowly rising temps overnight with near normal temps on Wed. Developing low pres over the SE coast will gradually lift up the eastern seaboard as a cold front approaches from the west. Rain expected to move in late Tue night although there is some uncertainty in the westward extent of the pcpn shield. Most of the rain associated with the front appears to dry up/lift N of the area where the better upper support is, with the remainder from the developing coastal low. Have likely PoPs mostly confined to eastern areas, but this may extend westward in later forecasts. 20/00z GFS is much further east than the remainder of consensus so it has been discounted. Rain should end by mid aftn Wed as the low pulls away, but it will become gusty as the low deepens and the pres gradient tightens. High pres then builds into the area with dry and cool weather through Fri night. Temps expected to avg 5-10 degrees below normal during this time. Another cold front approaches on Sat tracks across the area Sat night with a gusty NW flow expected in strong CAA on Sun. && .AVIATION /17Z MONDAY THROUGH SATURDAY/...
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High pressure builds to the southwest this afternoon, passes to the south, then southeast of Long Island tonight. VFR through the TAF period. Some ceilings hanging right around 5000ft, mainly across eastern Long Island and southeast Connecticut, will dissipate while worKing to the east this afternoon. W-WNW winds will continue through the afternoon with gusts around 25kt at most terminals. Winds will begin to back to towards the W-WSW late this afternoon/early this evening as gusts subside. SW gusts to around 20kt return mid to late morning on Tuesday. ...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. Isolated peak gusts could be up to 5 KT higher than gusts in TAFs. KLGA TAF Comments: Moderate-high confidence in winds to the left of 300 True/310 Magnetic. Isolated peak gusts could be up to 5 KT higher than gusts in TAFs. KEWR TAF Comments: High confidence in winds to the left of 300 True/310 Magnetic. Isolated peak gusts could be up to 5 KT higher than gusts in TAFs. KTEB TAF Comments: Isolated peak gusts could be up to 5 KT higher than gusts in TAFs. KHPN TAF Comments: Isolated peak gusts could be up to 5 KT higher than gusts in TAFs. KISP TAF Comments: Isolated peak gusts could be up to 5 KT higher than gusts in TAFs. .OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY... .Tuesday Afternoon-Tuesday evening...VFR. SW winds G20-30KT possible. 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. .Saturday...MVFR possible in showers. SW G15-25KT, highest at the coast.
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&& .MARINE... 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 with around 35 kt progged at 1k ft as LLJ moves across. SCA conds then expected behind cold fropa Wed/Wed night. Seas on the ocean may remain elevated on Thu due to a SE swell, but should subside on Fri. Sub-advsy conds on remaining waters Thu/Fri. && .HYDROLOGY... No hydrologic problems are anticipated the next 7 days. && .OKX WATCHES/WARNINGS/ADVISORIES... 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. && $$ SYNOPSIS...Tongue NEAR TERM...BC/Tongue SHORT TERM...Tongue LONG TERM...24 AVIATION...DW MARINE...Tongue HYDROLOGY...Tongue

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