Area Forecast Discussion
Issued by NWS Upton, NY

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999 FXUS61 KOKX 181152 AFDOKX Area Forecast Discussion National Weather Service New York NY 652 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/... The black ice threat remains across the region this morning, have addressed in an SPS valid through 14Z. A closed 700-500 hPa low passes to the south this morning, followed by shortwave ridging at 700-500 hPa building in this afternoon. With forcing from the closed low passing well to the south, then subsidence from the ridging this afternoon, it should be dry today. Other than some passing mid-high clouds this morning (mainly over southern zones), it should be mostly sunny today. Highs today should be around 5 degrees below normal, with afternoon wind chills from the upper 10s to mid 20s. && .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 /12Z THURSDAY THROUGH MONDAY/... High pressure builds south of the region through Friday. VFR conditions will remain through the TAF period. Winds and gusts have subsided early this morning. The winds will strengthen again, with gusts at or just above 20 kt for the late morning and into the afternoon. 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 just to the right for the aft/eve push. Winds and gusts subside Thursday evening. 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: Timing of winds going more NW for the late morning and early afternoon may be delayed by 1 to 2 hours. The afternoon KJFK haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KLGA TAF Comments: Timing of winds going more NW for the late morning and early afternoon may be delayed by 1 to 2 hours. The afternoon KLGA haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KEWR TAF Comments: Timing of winds going more NW for the late morning and early afternoon may be delayed by 1 to 2 hours. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Timing of winds going more NW for the late morning and early afternoon may be delayed by 1 to 2 hours. KHPN TAF Comments: Timing of winds going more NW for the late morning and early afternoon may be delayed by 1 to 2 hours. KISP TAF Comments: No unscheduled amendments expected. .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...Maloit SHORT TERM...Maloit LONG TERM...Goodman AVIATION...JE MARINE...Goodman/Maloit HYDROLOGY...Goodman/Maloit EQUIPMENT...

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