Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 220101 AFDOKX Area Forecast Discussion National Weather Service New York NY 801 PM EST Tue Nov 21 2017 .SYNOPSIS...
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A cold front approaches from the west tonight and passes through early Wednesday as low pressure develops along the eastern seaboard. High pressure builds in Wednesday through the end of the week. A cold front crosses Saturday night, with high pressure building in from the west for the beginning of next week.
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&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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Baroclinic leaf/cyclogenesis seen nicely on satellite this evening along the SE US coast as southern stream energy lifts up the coast. The phasing of an approaching northern stream energy with this southern stream energy, should result in a favorably strong right entrance jet region over the region late tonight into Wednesday morning. This lift interacting with Gulf/Atlantic moisture advecting up the coast should allow for a soaking rain across eastern portions of the region tonight. The exact location of deformation zone will determine how far west the heavier rain develops, with high-res models clustering across LI/CT. With large scale lift a period of light to moderate rain likely for NYC/Nj metro, lighter to the NW. Otherwise...rain develops late tonight into the overnight from southwest to northeast, mainly between 06-09Z. Total rainfall amounts generally between a half to 1 inch for Eastern Long Island and eastern Connecticut receiving the higher totals. Other areas will receive about a quarter of an inch, with lower totals NW of NYC/NJ metro. Temperatures tonight will fall into the 40s area wide, a blend of MET/MAV guidance was used.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Once the cold front passes during the morning, conditions are likely to quickly improve from west to east during the early afternoon with drier air ushering into the region. With cold air advection following the front, the end result will be falling temperatures throughout the day along with an increase in breezy NW winds by afternoon. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Continued agreement with the operational models for the first part of the long term period. High pressure at the surface, with the center over the Mid-Atlantic states, will keep the area dry for Thanksgiving. Cold air advection continues as noted in 12Z GFS soundings, so conditions will be much cooler than Wednesday. Given forecast soundings and 850 temperatures in the 0 to -4 C range for much of the area, highs should only reach the lower 40s, which is below normal for this time of year. Normal highs should be in the lower 50s. A cold front does pass north of the area, with a wind shift to the west, then west-southwest by the afternoon. High pressure pushes off the East Coast late Friday into Friday night as a warm front over the Eastern Great Lakes lifts well north of the area. Warm air advection doesn`t seem to kick in until Friday evening, so dry and continued cool for Friday, but slightly warmer than Thursday with highs in the middle to upper 40s. Another cold front approaches the area late Saturday and passes through Saturday night. Southwesterly flow ahead of the front will bring temperatures to normal levels to above normal levels, in the upper 40s to upper 50s. 12z GFS has trended drier with this run, which will warrant only slight chance for the entire area as there isn`t much moisture for the front to work with. It may be cold enough at the start for some frozen or freezing precipitation in much of Orange County Saturday morning, however, it will quickly change to rain. A surface trough or secondary weak cold front moves through on Sunday with a reinforcing shot of cold air. Some instability with the colder air aloft associated with the upper level trough may produce some light rain showers across the area, mainly for portions of Long Island. High pressure then keeps the area dry through the beginning of next week. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
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A cold front will approach tonight as low pressure moves up the coast. The front will pass through during Wed morning. VFR most of the night, then rain will spread into the terminals late tonight into Wed morning with MVFR conds developing, except then IFR conds at KISP/KGON. S-SW winds diminish tonight then shift NW and increase Weds morning, prevailing north of 310 magnetic. Gusts then become frequent during the aftn 20-25 kt. ...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: No unscheduled amendments expected. KLGA TAF Comments: No unscheduled amendments expected. KEWR TAF Comments: No unscheduled amendments expected. KTEB TAF Comments: No unscheduled amendments expected. KHPN TAF Comments: No unscheduled amendments expected. KISP TAF Comments: No unscheduled amendments expected. .OUTLOOK FOR 00Z THURSDAY THROUGH SUNDAY... .Wednesday night...VFR with NW gusts around 20KT in the evening. .Thursday through Friday night...VFR. .Saturday...VFR. SW winds G15-20KT. .Saturday night-Sunday...VFR. NW winds G20KT.
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&& .MARINE...
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Gales for this evening over the far eastern waters due to SSW gusts likely reaching gale force for several hours as high winds mix down over the eastern waters. After the gales subside late tonight around midnight, SCA will likely be needed for gusty winds and rough seas into Wed night. The cold front will be moving east of the forecast waters early Wednesday as high pressure builds to the west, with marginal SCA winds on ocean waters and possibly all waters in its wake. 5 to 6 ft waves on the ocean waters on Thursday will continue as a northwest flow shifts to the west-southwest. Waves will diminish Friday, generally coming down below 5 ft for most areas on the ocean by Friday afternoon. Waves increase again on the ocean late Friday night as a southwesterly flow sets up ahead of an approaching cold front, diminishing Saturday night. Winds should generally remain below 25 kt until Sunday afternoon as a northwest flow strengthens behind the passage of a cold front. Winds should remain above 25 kt from Sunday evening throughout the rest of the long term.
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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 ANZ335-338- 345. Gale Warning until midnight EST tonight for ANZ330-340-350. Small Craft Advisory until 6 AM EST Thursday for ANZ353-355.
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&& $$ SYNOPSIS...CB NEAR TERM...CB/NV SHORT TERM...CB LONG TERM...JP AVIATION...Goodman MARINE...CB/JP HYDROLOGY...CB/JP

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