Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 171445 AFDOKX Area Forecast Discussion National Weather Service New York NY 1045 AM EDT Tue Apr 17 2018 .SYNOPSIS... A couple of troughs of low pressure will cross the area through Wednesday, as an area of low pressure slowly lifts northeast from Northern New England into the Canadian Maritime Provinces. A low pressure system approaches Wednesday night and passes through the region Thursday. High pressure then gradually builds in through Monday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Weak shortwave ridging transits the area this morning, followed by a mid level shortwave trough rounding the base of an upper low this afternoon/early evening. This will result in mostly cloudy skies and isolated-scattered showers over the region. Today will be breezy (but the winds will not be quite as strong as yesterday) with highs around 5-10 degrees below normal.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... The northern stream troughing passes to the east this evening, bringing an end to any isolated-scattered showers from W to E. Lows tonight should be around 5-10 degrees below normal. The closed low lifts to the NE during the day on Wednesday allowing for northern stream shortwave ridging to build in Wednesday afternoon. It is this ridging that will allow sky conditions to become Mostly sunny over the region on Wednesday. Highs Wednesday should be around 5 degrees below normal. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Models agree that a low pressure system, probably with two low centers for a period, approaches Wednesday night and passes through the region during Thursday. Rain becomes likely by daybreak Thursday for most of the area with most of any rainfall happening from late evening on. Thermal profiles support rain for the most part, but will put in a chance of sleet mixing in across the northernmost zones Wednesday night should the cooler temps aloft shown by ECMWF occur. Rain remains likely through Thursday morning, then chances begin to drop off during the afternoon with the system shifting to our east. There could be some drizzle at times, but won`t add it to the forecast just yet. Leaned toward the cooler side of guidance for high temperatures on Thursday, averaging 7-10 degrees below normal. A cyclonic flow remains aloft on Friday, however high pressure at the surface slowly builds in, keeping us dry. Breezy and partly sunny with highs still around 7-10 degrees below normal. High pressure then continues to build in through Monday. Dry weather with high temperatures warming by a couple of degrees each day. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/...
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A cold front moves east of the terminals today, while a surface trough develops over the area this afternoon. Some MVFR ceilings (near 2.5-3 kft) until early afternoon but mostly VFR (near 4-6 kft) ceilings are expected through early this evening. Isolated afternoon/evening showers and/or snow showers are possible, but confidence is low in timing. Any precipitation is more likely to the north and west of NYC. Gusty westerly winds will prevail through today, becoming more frequent and increasing to 25 to possibly 30 KT this afternoon. Gusts subside and clouds decrease tonight. 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: Low confidence in shower timing, but locally reduced visibilities will be possible in any that develop this afternoon and early evening. The afternoon KJFK haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KLGA TAF Comments: Low confidence in shower timing, but locally reduced visibilities will be possible in any that develop this afternoon and early evening. The afternoon KLGA haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KEWR TAF Comments: Low confidence in shower timing, but locally reduced visibilities will be possible in any that develop this afternoon and early evening. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Low confidence in shower timing, but locally reduced visibilities will be possible in any that develop this afternoon and early evening. KHPN TAF Comments: Low confidence in shower timing, but locally reduced visibilities will be possible in any that develop this afternoon and early evening. KISP TAF Comments: Low confidence in shower timing, but locally reduced visibilities will be possible in any that develop this afternoon and early evening. .OUTLOOK FOR 12Z WEDNESDAY THROUGH SATURDAY... .Wednesday...VFR. W G20 kt possible. .Wednesday night-Thursday...Chance of MVFR and rain. .Thursday night-Friday...MVFR or lower possible in mainly rain with a wintry mix possible to the NW of city terminals late Thursday night/Friday morning. .Saturday...VFR.
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&& .MARINE...
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SCA conditions will prevail into Wednesday with a strong west flow behind departing low pressure lifting up into eastern Canada. These conditions should continue through around midday Wednesday W of Fire Island Inlet and through most, if not all the afternoon E of there. On the non-ocean waters gusts to around 25 kt should develop by early afternoon and continue through at least tonight. Seas will linger up to around 5 ft on the eastern ocean waters Wednesday evening before briefly subsiding below advisory criteria late at night. Low pressure passing through with a gusty NW flow behind it will bring some SCA-level gusts to most of the waters on Thursday, and ocean seas will build back up to 5-6 ft at this point. NW gusts could keep the ocean waters at advisory criteria all the way through Friday night, then building high pressure will kick off what appears to be an extended period of tranquil conditions over all waters starting Saturday.
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&& .HYDROLOGY...
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All areal flood advisories have been discontinued as water level continue to recede. There may be isolated areas of minor flooding along some smaller rivers and streams. Less than a few hundredths of an inch of rain is expected this afternoon and evening, so no significant hydrologic impacts are expected. Rain amounts below a half inch are expected Wednesday night through Thursday evening with no hydrologic impacts anticipated. Dry weather follows thereafter.
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&& .TIDES/COASTAL FLOODING... Water levels are expected to stay below minor flood thresholds for this morning/early afternoon high tide. However, the thresholds for minor coastal flooding could be approached, mainly along the coasts of the back shore bays of S Queens/S Nassau and SW Suffolk counties, during the high tide tonight/early Wednesday morning. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off the air. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ330-335- 338-340-345. Small Craft Advisory until 6 PM EDT Wednesday for ANZ350-353. Small Craft Advisory until noon EDT Wednesday for ANZ355.
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&& $$ UPDATE...DW AVIATION...MD/JM

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