Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 180232 AFDOKX Area Forecast Discussion National Weather Service New York NY 932 PM EST Wed Jan 17 2018 .SYNOPSIS... Low pressure moves into the Canadian Maritimes tonight. High pressure builds in through Thursday. The local area will be between low pressure to the north and high pressure to the south on Friday, both of which depart to the east over the weekend. A warm front will slowly lift to the north on Monday, then a cold front will pass through on Tuesday. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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Hazardous travel overnight into early Thursday morning due to black ice formation on untreated surfaces. Becoming clr overnight as the low pulls away to the northeast. The fcst remains on track. Cold temperatures will return for tonight with lows falling into the teens for the outlying areas, while temperatures in and around New York City will be around 20 degrees.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... A closed low remains SE of Long Island on Thursday as ridging builds into the area. Mostly sunny with temperatures in the low 30s, about 5 degrees below normal. W-NW winds 10-15 kt, with the strongest winds along the coast. Shortwave trough passes through dry Thursday night. Lows drop down into the teens to low 20s. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... NWP is in relatively good agreement with the overall H5 pattern across North America through the period. There are some differences in timing and strength with a fairly strong system moving through the Great Lakes and northeast during the first half of next week, which will hopefully be worked out over the next few days. A split flow will reside over the CONUS at the start of the long term. After a shortwave trough passes through New England early Fri morning, the H5 flow will flatten in response to another northern stream trough diving across central and eastern Canada. Zonal flow will generally prevail through the weekend, with an amplifying ridge developing Sun night/Mon as an upper level trough cuts off in the Rockies and continues into the central plains. This system will continue NE through the Great Lakes and Northeast Tue night into Wed. At the sfc, dry weather will dominate through the weekend although a brisk westerly flow will develop on Sat due to a tightening pressure gradient between low pres to the north and high pres to the south. A leading warm front will approach our area late Sun night into Mon, and its progress may be delayed by high pressure to the NE. There could be some spotty wintry precip inland late Sun night into Mon morning, otherwise light rain into Mon evening. Followed slower model trend with a cold front trailing from the Great Lakes low, with it moving through on Tue. We could be setting up for a moderate to locally heavy rain event during this time as the low taps Atlantic moisture via a strengthening LLJ, with both it and difluent flow aloft likely providing enhanced lift, and a possible triple point low passing nearby and concentrating low level convergence. && .AVIATION /03Z THURSDAY THROUGH MONDAY/...
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High pressure builds to the south of the region tonight through Thursday Night. Lingering MVFR this evening, will give way to VFR overnight and through the remainder of the TAF period. NW winds with gusts to around 20 kt for NYC/NJ terminals through the evening. Occasional gusts elsewhere. Winds and gusts should subside late tonight, before strengthening again with gusts 20 to 25 kt after sunrise on Thursday. Winds will likely waver between 300 and 330 magnetic during the day, likely averaging just left of 310 magnetic for the morning push and then to the right for the aft/eve push. Winds and gusts subside Thursday evening. .OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY... .Thursday Night...VFR. .Friday...VFR. W-SW winds G20KT possible. .Saturday-Sunday...VFR. .Monday...MVFR or lower possible in -SHRA, mainly late.
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&& .MARINE... Pressure gradient over the waters will allow winds and seas to remain at SCA levels. Winds on the ocean waters will have gusts up to 25 kt and seas 4 to 6 feet, therefore have kept SCA through 6 PM Thursday. There is a possibility that the SCA will have to be extended for the far eastern waters for both winds and seas into Thursday night, but confidence is too low at this time. Marginal SCA conds are possible on the ocean waters Fri. SCA conds are also likely Sat into Sat evening on the ocean as a moderate W flow develops between low pressure passing well to the north and high pressure building to the south. Tranquil conds on all waters then expected through Sun night. && .HYDROLOGY... No significant hydrologic impacts are expected through at least the upcoming weekend. A frontal system passing through Mon night into Tue has potential to bring over an inch of rain during that time. Mainly nuisance urban/poor drainage impacts expected attm. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 PM EST Thursday for ANZ350-353- 355. && $$ SYNOPSIS...CB/24 NEAR TERM...12/JC SHORT TERM...CB LONG TERM...24 AVIATION...NV MARINE...CB/24 HYDROLOGY...CB/24 EQUIPMENT... is the U.S. government's official web portal to all federal, state and local government web resources and services.