Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 181418 AFDOKX Area Forecast Discussion National Weather Service New York NY 918 AM EST Thu Jan 18 2018 .SYNOPSIS... High pressure builds to the southwest through tonight, then well to the south of Long Island Friday and Friday night, as an area of low pressure passes well to the north of the region, then both of these continue to move east on Saturday. A back door cold front will pass through late Saturday night into Sunday, then lift back slowly north as a warm front Monday into Monday night. A stronger cold front will approach from the west late Monday night, and pass through on Tuesday. A secondary cold front approaches from the north on Tuesday night, then pushes to the south on Wednesday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Updated temperatures to reflect latest observations. Otherwise forecast on track. Mostly sunny day other than some passing mid-high clouds this morning (mainly over southern zones) as shortwave ridging builds. Highs today should be around 5 degrees below normal. W-NW winds with occasional gusts 15-20 kt this afternoon with wind chills in the teens to mid 20s.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... The 700-500 hPa shortwave ridging exits to the east this evening, followed by a 700-500 hPa shortwave trough passing by overnight. With the subsidence from the ridging this evening, and the main from the shortwave staying to the north of the region, it should be dry tonight. Could see some passing mid-high clouds overnight with the shortwave, with the best chance over N zones. Lows tonight should be around 5 degrees below normal, with wind chills from around 10 to 20 degrees. Weakening northern stream ridging at 700-500 hPa crosses the area Friday, giving way to zonal flow aloft Friday night. With shortwaves staying well to the N and S of the area, and dry low to mid levels, it should be dry with minimal cloud cover during this time frame. Highs Friday should be near to slightly below normal, and lows friday night around 5 degrees above normal. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Flow aloft will be mainly zonal this weekend between a flat trough to the north and a ridge over the Southeast. The resulting return flow should give us a mild weekend, with highs on Sat in the lower 50s, then 45-50 on Sunday with approach/passage of a weak back door cold front. High pressure will nose down into New England Sunday night into Mon while a warm front associated with strengthening low pressure moving NE across the Plains States approaches. There is some question as to amount of warming aloft that will take place with the front, and some spotty light wintry precip is possible late Sunday night into Mon morning, especially inland NW of NYC. Precip chances should gradually increase Mon afternoon/evening with the warm front just off to the SW, and deep layer SW flow having begun after passage of an upper ridge axis. Models continue to trend later with moderate to locally heavy rainfall ahead of a sfc cold front and negatively tilted upper trough, and have pushed greatest chances ahead to daytime Tue. Temps on Tue ahead of the front should be on the mild side, with upper 40s inland and lower 50s NYC metro/Long Island. Temps should cool down thereafter for mid next week but still remain above avg, with building high pressure after the cold frontal passage being a combo of maritime Pacific and/or modified Continental polar origin. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... High pressure builds south of the region through Friday. VFR. Winds primarily north of 310 magnetic this morning, backing mostly south of 310 near 18-19z. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/ KJFK TAF Comments: Gusts might be only occasional this morning. The afternoon KJFK haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KLGA TAF Comments: Gusts might be only occasional this morning. The afternoon KLGA haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KEWR TAF Comments: Occasional gusts to around 20 kt possible before 18z. Winds potentially prevail south of 310 magnetic all morning. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Occasional gusts 16-19 KT possible this morning. KHPN TAF Comments: Occasional gusts 16-19 KT possible this morning. KISP TAF Comments: Gusts might be only occasional this morning. .OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY... .Friday...VFR. W-SW winds G15-20KT possible. .Saturday...VFR. WSW winds G20-25KT. .Sunday...VFR. .Monday...MVFR or lower possible in -SHRA, mainly late. && .MARINE... A moderate pressure gradient remains over the waters through Friday night, with sustained winds up to 20 kt and gusts up to 30 kt on the coastal ocean waters and 15 kt with gusts up to 20 kt on the non-ocean waters. Seas on the coastal ocean waters fall to below 5 ft by Friday morning, there also could be a few hours with gusts below 25 kt on the coastal ocean waters late tonight and early Friday morning. As a result, have extended the SCA on the coastal ocean waters through tonight. At this time, confidence is not quite high enough to extend it into Friday. SCA conds likely on the ocean E of Fire Island Inlet Sat into Sat evening as a moderate W flow prevails between low pressure well to the north and high pressure to the south. As a back door cold front approaches and then passes through later Sat night into Sunday, quiet conds expected on all waters thereafter into late Mon night, when winds and seas on the ocean could again approach SCA conditions in SE-S flow ahead of an approaching cold front. && .HYDROLOGY... It should be dry through the weekend. A frontal system passing through early next week has potential to bring over an inch of rain during that time. Mainly nuisance urban/poor drainage impacts expected at this time. && .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 AM EST Friday for ANZ350-353-355. && $$ SYNOPSIS...Goodman/Maloit NEAR TERM...CB/Maloit SHORT TERM...Maloit LONG TERM...Goodman AVIATION...JC/JE MARINE...Goodman/Maloit HYDROLOGY...Goodman/Maloit EQUIPMENT... is the U.S. government's official web portal to all federal, state and local government web resources and services.