Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 231115 AFDOKX Area Forecast Discussion National Weather Service New York NY 615 AM EST Thu Nov 23 2017 .SYNOPSIS... High pressure builds to the south through Friday, then pushes well of the Atlantic coast into Saturday. A cold front approaches from the west Saturday, then crosses the area Saturday night. High pressure then builds in from the southwest through Monday night, then slides off the Mid-Atlantic coast Tuesday. A cold front approaches from the west Tuesday night, then crosses the area on Wednesday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Made minor changes this update to reflect the latest trends in observations and guidance. The forecast appears on track. A 700-500 hPa trough approaches today, but with dry low-mid levels it should be dry, with just some patchy high clouds out ahead of it, mainly in the afternoon. Highs today should be 5-10 degrees below normal, mainly from around 40 to the lower 40s.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... The trough crosses the region in pieces, with the northern stream portion crossing the area this evening, and the southern stream portion overnight. Given the unphased nature of the trough and relatively dry mid-upper levels, have continued with a dry forecast for tonight. Lows tonight should be around 5 degrees below normal, mainly from the mid 20s to around 30, except low-mid 30s in the NYC metro. Southwest flow sets up aloft on Friday, with no notable shortwave progged to pass over the area in this flow, it should be dry, with minimal, if any cloud cover. Highs should be near normal. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... SW flow aloft continues Friday night, and absent any shortwaves in the flow, it should continue to be dry, with minimal cloud cover. Lows Friday night should be near to slightly above normal. A deep layered trough approaches on Saturday, models do differ on how well phased it is. The GFS is the most coherent between the northern and southern streams, while the ECMWF/CMC/NAM have the northern stream trough progressing quicker than the southern stream trough, and shearing out as it lifts NE. The SREF has similar coherence to the GFS, but is slower with the overall system. Noting that the northern stream currently is more progressive than the southern stream, have leaned more towards the ECMWF/CMC/NAM Saturday/Saturday night. However, do have slight chance pops mainly Saturday afternoon (and into the evening far E zones) with the addition of lift just ahead of the surface cold front. The region remains at the base of a northern stream trough Sunday-Sunday night. However, given dry low levels, have continued with a dry forecast. Deep layered ridging builds from Monday into Tuesday, then slides off shore through Tuesday night. Subsidence associated with the ridge should keep things dry, with minimal cloud cover. Models then differ on Wednesday. The CMC has a closed low N of the Great Lakes with and associated full latitude trough building into the deep south. The ECMWF has a shearing out northern stream shortwave race by to the north. The GFS is fairly similar to the ECMWF, however, not quite as flat with the shortwave/overall pattern over the eastern U.S. Since the CMC appears to be a clear outlier, went with a GFS/ECMWF blend. With expectation of relatively dry-low to mid levels and limited dynamics to work with, limited pops on Wednesday to slight chance, as some isolated showers cannot be ruled out. Temperatures Saturday-Wednesday, start out above normal on Saturday, should be below normal Sunday-Monday, then above normal Tuesday and Wednesday. && .AVIATION /11Z THURSDAY THROUGH MONDAY/...
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High pressure builds in from the west today into tonight. VFR. NW winds around 10 kt (right of 310 magnetic) for the morning push, likely backing to the west (left of 310 magnetic) in the afternoon. Winds subsiding to less than 5 kt this 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 backing from right of 310 magnetic to left of 310 magnetic could be off 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 backing from right of 310 magnetic to left of 310 magnetic could be off 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 backing from right of 310 magnetic to left of 310 magnetic could be off 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 backing from right of 310 magnetic to left of 310 magnetic could be off by 1 to 2 hours. KHPN TAF Comments: No unscheduled amendments expected. KISP TAF Comments: No unscheduled amendments expected. .OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY... .Late tonight-Friday night...VFR. Light W winds back to the SW Friday. .Saturday-Saturday night...Low prob of -SHRA and MVFR with frontal passage. Windshift from SW to NW late Sat/Sat Eve. .Sunday...Becoming VFR. NW winds G20-30KT forecast. .Monday...VFR. Winds back to more westerly and decrease. Gusts 15-20KT possible.
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&& .MARINE...
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Made minor changes this update to reflect the latest trends in observations and guidance. The forecast appears on track. Wind gusts are expected to fall below Small Craft Advisory (SCA) levels early this morning, but seas remain at 4 to 6 ft. Although winds waves will begin to decrease, WNA/NWPS guidance indicating a 5ft@10 sec period swell beginning to work into the waters this morning and being slow to subside through Friday. Hints of this swell just beginning to show up at 44066 and 44008 this morning. So 5 ft seas are likely today on the ocean. With a slight strengthening of pressure gradient and caa tonight, the marginal SCA seas may linger through tonight into Friday, particularly for eastern ocean waters. SW gradient picks up late Friday into Friday night, which would signal likelihood for SCA ocean seas remaining/developing late Friday into Friday night and continuing into Saturday, particularly east. Sub SCA conditions are expected on all non-ocean zones through Saturday. SCA conds likely all waters late Saturday night through Sunday behind a cold front, with improvement on Monday as high pressure builds to the south. Ocean seas may builds towards SCA once again Tuesday into Tuesday Night ahead of next frontal system.
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&& .HYDROLOGY... With the potential for most, if not all areas to be dry through next Wednesday, no significant hydrologic impacts are expected through then. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 7 PM EST this evening for ANZ355. Small Craft Advisory until 7 AM EST Friday for ANZ350-353. && $$ SYNOPSIS...Maloit NEAR TERM...Maloit SHORT TERM...Maloit LONG TERM...Maloit AVIATION...NV MARINE...Maloit/NV HYDROLOGY...Maloit

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