Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 171918 AFDOKX Area Forecast Discussion National Weather Service New York NY 218 PM EST Wed Jan 17 2018 .SYNOPSIS... Low pressure tracks from south of Long Island into the Gulf of Maine today. High pressure then builds in from the southwest through Thursday, then to the south through Friday, and then moves into the western Atlantic this 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 PM THIS EVENING/... Minor changes with this update to reflect latest radar trends. Back edge of the snow is pushing from west to east. Have kept likely PoPs through 19z for extreme eastern LI and southeast CT. Winter headlines for NY have been allowed to expire and plan on allowing CT headlines to expire at 18Z. Low level cold advection in the wake of the coastal low should lower temperatures into this afternoon. Temps are expected to be mostly 30-35 across the area by sunset. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... A closed 700-500 hPa low tracks across the Mid Atlantic States tonight, then to the SE of Long Island on Thursday, as northern stream shortwave ridging builds into the area. Given that the best forcing stays to the S tonight, and subsidence from the ridging on Thursday, it should be dry both periods. AS far as cloud cover goes, should see decreasing cloud cover tonight from W to E, then mostly sunny sky conditions on Thursday. Lows tonight should be up to 5 degrees below normal and highs on Thursday around 5 degrees below normal. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Surface high pressure will build to our south through Friday. An upper trough passing through Thu night into Fri morning should bring an increase in clouds but no precip. Temps on Friday should be slightly above avg. As low pressure passes to the north and high pressure to the south on Sat. expect a brisk W flow to develop, especially along the coast. These winds should weaken on Sunday as the low continues east. GFS and ECMWF disagree a little as to whether the flat upper ridge to the south or the flat trough to the north will prevail, but at any rate temps will continue to trend above avg into the weekend, with highs 45-50 if not a little higher. An amplifying but progressive upper trough entering the Plains states late this weekend will send sfc low pressure NE toward the upper Great Lakes. A leading warm front will approach our area late Sunday night into Mon, and its progress may be delayed by high pressure to the NE. There could be some spotty wintry precip inland late Sunday 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 its approach late Mon night into 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 /19Z WEDNESDAY THROUGH MONDAY/...
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Precipitation will gradually taper off from west to east, with an hour or two of haze possible after precipitation ends. Otherwise, a slow return to VFR is expected this evening. As conditions improve, winds will begin to strengthen from the WNW-NW, with gusts around 20 kt. Gusts may continue a few hours into the overnight before diminishing, only to strengthen again after sunrise on Thursday. 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 VFR conditions may be off by +/- 1 to 2 hours. KLGA TAF Comments: Timing of VFR conditions may be off by +/- 1 to 2 hours. KEWR TAF Comments: Timing of VFR conditions may be off by +/- 1 to 2 hours. KTEB TAF Comments: Timing of VFR conditions may be off by +/- 1 to 2 hours. KHPN TAF Comments: Timing of VFR conditions may be off by +/- 1 to 2 hours. KISP TAF Comments: Timing of VFR conditions may be off by +/- 1 to 2 hours. .OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY... .Thursday-Thursday Night...VFR. WNW winds G20KT on Thursday. .Friday...VFR. W-SW winds G15-20KT possible. .Saturday-Sunday...VFR. .Monday...MVFR or lower possible in -SHRA, mainly late.
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&& .MARINE... A moderate pressure gradient over the waters will allow winds on the ocean waters to reach up to 20 kt with gusts up to 25 kt through Thursday and over the non-ocean waters up to 15 kt with gusts up to 20 kt through Thursday. With seas on the ocean waters forecast to 3 to 7 ft as well, have extended the Small Craft Advisory (SCA) there through 6PM Thursday. Marginal SCA conds may continue on the outer ocean waters into Thu night and 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. && .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...
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NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the air for an extended period of time. The Riverhead (RVH) NOAA Weather Radio Station WXM-80 (162.475) is emitting a loud buzzing noise that is currently being assessed by technicians.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 PM EST Thursday for ANZ350-353- 355.
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&& $$ SYNOPSIS...Goodman/Maloit NEAR TERM...JC SHORT TERM...Maloit LONG TERM...Goodman AVIATION...MD/JE MARINE...Goodman/Maloit HYDROLOGY...Goodman/Maloit EQUIPMENT...

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