Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 052053 AFDOKX Area Forecast Discussion National Weather Service New York NY 353 PM EST Mon Dec 5 2016 .SYNOPSIS...
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High pressure will drift across from the west through Tuesday morning, then retreat to New England Tuesday afternoon and night. Meanwhile, low pressure approaching from the west will redevelop off the North Carolina coast late Tuesday, and pass slowly to the south Tuesday night into Wednesday. Low pressure will remain across southeastern Canada Wednesday night through Friday, with a cold front passing through on Thursday. High pressure will build in from Friday night through Saturday night, then move off the coast Sunday into Monday as a warm front and low pressure approach.
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&& .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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High pressure will build in, with skies becoming mostly clear, This clearing should take a little longer well north/west of NYC until weak low level cyclonic flow subsides. Low temps should be in the 20s inland, and 30s NYC metro and along the coast.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
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After a sunny start, high clouds will increase in the late morning and afternoon as the upper ridge axis slides across. As a closed low associated with a closed low ejecting out of the Southern plains opens up into a mid level trough as it moves into the ridge, associated sfc low pressure in the OH/TN valleys should start to redevelop late in the afternoon along the NC coast, and could bring a chance of rain to NYC metro and the Lower Hudson Valley late in the afternoon. High temps will be in the 40s. There are some model timing and intensity differences with the approaching system for Tue night. The NAM is faster and has a more ideal juxtaposition of synoptic and mesoscale lift via the approaching trough, the left entrance of an upper jet streak, and mid level frontogenesis. This lift also leads to more dynamic cooling aloft and greater potential for snow across the interior. Meanwhile the GFS/ECMWF are slower, not quite as wet, and warmer, with less potential for snow inland. The official forecast straddles these two scenarios, with potential for a 1-2 inch snowfall inland, a coating to an inch just inland of I-95 in CT and I-287 in the lower Hudson Valley and interior NE NJ, and little to no accumulation farther south where precip will be mostly in the form of light rain. Mid level moisture heads to the east by Wed morning, with any lingering precip changing mostly over to rain. Some clearing expected across the western half of the area. High temps will once again be in the 40s per guidance blend.
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&& .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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A closed upper low that is nearly stacked will remain across southeastern Canada Wednesday night into Friday. Meanwhile a shortwave will be rotating through the upper trough with a cold frontal boundary and trough moving through the Mid Atlantic Thursday. This cold front will bring a cold air mass into the Northeast with temperatures running around 10 degrees below normal. There is still some uncertainty as too how quickly the cold airmass will reach the northeast before becoming modified. The upper low opens and moves out late Friday and Friday night with weak upper ridging. The upper flow become nearly zonal across the continental United States Friday night and through the weekend. With high pressure moving off the northeast coast Sunday a return flow develops and warm advection sets up into Monday. Friday night the next shortwave to affect the area will be moving on shore of the Pacific northwest and quickly move across the country. Cyclogenesis occurs across the central plains Sunday into Sunday night with the low tracking through the Great Lakes. Precipitation Sunday night may start as snow inland and transition to rain Monday and will be dependent on how quickly the warmer air moves into the area. If a warmer layer moves in aloft before the low level cold air is scoured out there will be a chance for some freezing rain Sunday night. With the uncertainty did not include in the forecast at this time and leaned toward a warmer solution.
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&& .AVIATION /20Z MONDAY THROUGH SATURDAY/...
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A frontal system exits east of the region with a westerly flow continuing this afternoon. High pressure builds in thereafter through the rest of the TAF period. W-NW winds gusting to 15-20 kt will diminish going into tonight. VFR is expected through Tuesday morning. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/www.weather.gov/zny/n90 KJFK TAF Comments: Wind direction occasionally veering 10-30 degrees right of forecast before 23Z. An occasional gust to 20-25 kt is possible this afternoon. KLGA TAF Comments: Wind direction occasionally veering 10-30 degrees right of forecast before 23Z. An occasional gust to 20-25 kt is possible this afternoon. KEWR TAF Comments: Wind direction occasionally veering 10-30 degrees right of forecast before 23Z. An occasional gust to 20-25 kt is possible this afternoon. KTEB TAF Comments: Wind direction occasionally veering 10-30 degrees right of forecast before 23Z. An occasional gust to 20-25 kt is possible this afternoon. KHPN TAF Comments: Wind direction occasionally veering 10-30 degrees right of forecast before 23Z. An occasional gust to near 20 kt is possible this afternoon. KISP TAF Comments: Wind direction occasionally veering 10-30 degrees right of forecast before 23Z. An occasional gust to 20-25 kt is possible this afternoon. .OUTLOOK FOR 20Z TUESDAY THROUGH SATURDAY... .Tuesday...MVFR possible with a chance of light rain. Light snow possible inland. .Tuesday night-Wednesday...MVFR/IFR in light rain with light snow possible inland. .Wednesday night-Thursday night...VFR. .Friday-Friday night...VFR. NW winds 15-20 kt, gusts 25-30 kt. .Saturday...VFR. NW winds 15 kt gusts 20-25 kt.
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&& .MARINE...
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SCA in effect for the ocean and eastern Long Island Sound through tonight as high pressure builds in and NW flow gusts up to 25-30 kt, highest S of Montauk. Ocean seas should also reach 5 ft S of Montauk, but remain less than 5 ft farther west due to limited offshore fetch. Winds and seas will remain below SCA levels Wednesday night through Thursday as low pressure remains to the north across southeastern Canada. A cold front will move through Thursday and a strong and gusty northwest flow will develops. Thursday night SCA gusts develop on the ocean waters, and then during Friday winds increase, with marginal gale force gusts possible on the ocean waters, and SCA gusts on the remainder of the forecast waters. Gale and SCA gusts continue into Friday night, then subside late as high pressure begins to build to the west. Saturday morning winds and seas are expected to be below SCA levels on all the waters as high pressure continues to build.
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&& .HYDROLOGY... No hydrologic impacts 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 6 AM EST Tuesday for ANZ330-350-353- 355.
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&& $$ SYNOPSIS...Goodman/MET NEAR TERM...Goodman SHORT TERM...Goodman LONG TERM...MET AVIATION...JM MARINE...Goodman/MET HYDROLOGY...Goodman/MET

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