Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 181109 AFDOKX Area Forecast Discussion National Weather Service New York NY 609 AM EST Tue Dec 18 2018 .SYNOPSIS... High pressure slowly builds in across the area into Wednesday and shifts into the Western Atlantic by Thursday. This gives way to an approaching and deepening area of low pressure from the Southeast US Thursday night into Friday. The low continues to strengthen and move northward across the Northeast west of the Hudson Valley Friday through Friday night. For the weekend, the low moves into the Canadian Maritimes and high pressure builds in from the Southeast US. Weak low pressure approaches close to the region for late this weekend into early next week from the west. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... High pressure builds in at the surface and aloft while a storm over the Canadian Maritimes slowly shifts east. The combination of these features will maintain a relatively tight pressure gradient over us and bring us another breezy day. Sunny, but colder than normal along with wind chills in the 20s. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... The high pressure ridge axis approaches us tonight and shifts through on Wednesday. Winds therefore diminish tonight and remain on the lighter side through Wednesday night. Mostly clear conditions expected through at least this evening, then varying amounts of over- the-ridge cirrus are anticipated thereafter. Low temperatures tonight below normal, then highs around normal on Wednesday. Wednesday`s lows for the most part are expected to end up a little above normal, however spots more prone to radiational cooling could end up below normal if cirrus isn`t too prevalent. && .LONG TERM /THURSDAY THROUGH MONDAY/... Offshore high pressure based in the Western Atlantic Thursday will eventually give way to approaching low pressure which will be the focus of the long term. Winds will become more southeasterly. Mild temperatures in the low to mid 40s are forecast for the day with mainly dry conditions, although towards Northeast NJ, Lower Hudson Valley and into NYC, POPs will increase in the afternoon for rain. The main focus of the long term will be a developing mid latitude cyclone moving along the Appalachians and up along the Hudson Valley deepening from Thursday night through Friday night. The associated warm front approaches Thursday night into early Friday and then moves across during the day Friday. Rain becomes likely Thursday night with categorical POPs late Thursday night through Friday morning. There will be rising temperatures into the upper 40s to lower 50s Thursday night with increasing warm and moist air advection via strengthening southeasterly flow. This will be when a strong low level jet, as conveyed by NAM and GFS Bufkit profiles to be near 70kt in the 800-900mb layer. Strong inversion just above the surface will limit gust potential on land with exception of any heavy rain which could bring down the higher gusts of perhaps 40kt. Rain could become heavy at times especially in the late Thursday night through early Friday timeframe. Models show potential for enhanced lift with deep omega appearing in this timeframe as well. After the warm frontal passage, there will continue to be rain showers and with elevated instability in the warm sector, there will be a few thunderstorms possible as well. This will potentially result in heavy rain. Max temperatures Friday are forecast in the upper 50s. The region remains in the warm sector Friday night with showers becoming more occasional in frequency and fog will be possible as well with the moisture laden grounds and decreasing winds. Min temperatures forecast Friday night are only in the low to upper 40s. For the weekend, low pressure moves northeast into the Canadian Maritimes Saturday into Saturday night. A series of cold fronts pass at the surface, one early Saturday and another one passing through at night. Yet another cold front looks to move across late Sunday night into Monday. Mainly dry conditions expected for the weekend into early next week with just a slight chance of a shower Saturday afternoon and late Sunday night. Temperatures return to closer to normal values. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/...
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Strong low pressure near the Canadian Maritimes will slowly move east as high pressure slowly builds from the west. The pressure gradient between the two will support gusty NW winds, with direction around 320 magnetic most sites, speeds 15-20 kt with frequent gusts 25-30 kt most of today. A few peak gusts just over 30 kt could occur this morning. Winds could be a little higher than that at KISP/KGON from late morning into early afternoon. NW winds slowly diminish tonight. ...NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component fcsts, can be found at: http://www.weather.gov/zny/n90 KJFK TAF Comments: A few gusts close to 35 kt early. The afternoon haze potential forecast is GREEN, which implies slant range visibility P6SM outside of cloud. KLGA TAF Comments: A few gusts close to 35 kt early. The afternoon haze potential forecast is GREEN, which implies slant range visibility P6SM outside of cloud. KEWR TAF Comments: A few gusts close to 30 kt early. The afternoon haze potential forecast is GREEN, which implies slant range visibility P6SM outside of cloud. KTEB TAF Comments: A few gusts close to 30 kt early. KHPN TAF Comments: A few gusts close to 35 kt early. KISP TAF Comments: A few gusts close to 35 kt early. .OUTLOOK FOR 12Z WEDNESDAY THROUGH SATURDAY... .Wednesday...VFR. .Thursday...Rain with MVFR conds developing in the afternoon. .Thursday night...Rain. MVFR conds in the evening. IFR conds, SE winds 15G20kt and LLWS after midnight NYC metro/coast. .Friday...Rain with IFR/LIFR conds. SE winds 20G25kt, LLWS, and chance of a tstm in the morning NYC metro/coast. Warm fropa with winds becoming S 10-15G20kt in the afternoon. .Friday night...MVFR or lower conds with intermittent showers. .Saturday...Mainly VFR. W winds G20-25kt.
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&& .MARINE... Cold air advection along with a tight pressure gradient will likely maintain gale force gusts on all waters at the start. Then as a high pressure ridge approaches, winds and seas gradually diminish. End times for the gale warning are unchanged for the time being, and SCA conditions will follow. All waters should fall below advisory criteria by Wednesday morning. Then as the center of high pressure nears and passes through, tranquil conditions for Wednesday and Wednesday night. Gales possible on the waters late Thursday night into Friday with any enhanced mixing from low level jet. Otherwise in terms of wind gusts, forecast has below SCA winds Thursday into Thursday evening. SCA level wind gusts late Thursday night on the ocean with all waters having SCA level gusts Friday and then just the ocean Friday night. SCA level gusts on all waters forecast for Saturday and Saturday night. Seas are all below SCA Thursday into Thursday evening and then late Thursday night, ocean is forecast to reach SCA seas. The ocean pretty much stays in SCA range for seas for the rest of the forecast period while non-ocean waters stay below SCA except for Eastern Long Island Sound this weekend. && .HYDROLOGY... Widespread rain of 1.5 to 2 inches possible for late week with locally higher amounts but still uncertainty in terms of amounts. Minor flooding will be a possibility. && .TIDES/COASTAL FLOODING... Full moon coming up on December 22. Potential of widespread minor coastal flooding with possible moderate coastal flooding particularly for South Shore Bays Friday with piling water and increasing SE flow. Surge of 1-2 ft needed for most locations to reach coastal flood benchmarks. Possible coastal flooding but to a lesser extent for Saturday. && .EQUIPMENT... NYC Central Park winds are out of service until further notice. Loss of data is due to a severed cable. Parts are on order. NYC NOAA Weather Radio Station KWO35 (162.55 MHz) will remain off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Gale Warning until noon EST today for ANZ330-335-338-340-345. Gale Warning until 6 PM EST this evening for ANZ350-353-355. && $$ SYNOPSIS...JC/JM NEAR TERM...JC SHORT TERM...JC LONG TERM...JM AVIATION...Goodman MARINE...JC/JM HYDROLOGY...JC/JM TIDES/COASTAL FLOODING... EQUIPMENT...

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