Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 190300 AFDOKX Area Forecast Discussion National Weather Service New York NY 1100 PM EDT Fri Aug 18 2017 .SYNOPSIS... A cold front will move slowly east across the area late tonight, then stall just east of Long Island on Saturday. High pressure will follow Saturday night through Tuesday. A cold front will pass across the area Wednesday night followed by high pressure. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Main update this evening to cancel the flash flood and severe thunderstorm watches, as convection is rapidly diminishing in intensity. A few spotty convective showers and stratiform precipitation remain, but should pose little threat for the remainder of the evening. Leftover showers and TSTMs will end with the passage of the cold front between 06z and 12z overnight. With light winds forecast during this time, areas of fog will develop, possibly dense across Long Island and Southern CT where significant rainfall fell earlier in the day. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... With a digging upstream trough approaching Saturday, the cold front may not make it too far off the Long Island coast. In fact, it`s possible that it might retrograde a bit until the passage of this trough Saturday night. Dryer air will advect east across the area Saturday night as high pressure advects east toward the area. && .LONG TERM /SUNDAY THROUGH FRIDAY/... A broad area of high pres will build in Sun and Mon. This will produce seasonable temps and mostly clear skies. A thermal ridge will build into the region Tue into Wed, producing a mini heat wave. Some spots, particularly across nern NJ, may hit the 2 day heat advy criteria. As subtropical moisture becomes entrained in the flow, an increase in high clouds can be expected by Wed. The cold frontal timing has slowed slightly from the previous 12Z model suite, so right now the timing is for the late aftn and eve. Although the best chance for tstms will be with the fropa Wed, there will be chances prior, albeit lower, due to the unstable airmass and onset of lowering heights. Because of the progged position of the front and tendency of the guidance to smooth out the temp gradient, highs were manually raised on Wed. A significant cool down then looks to follow for the end of the week. The models have been very consistent with this signal, although the exact magnitude of the cold airmass remains in question. It would not be totally surprising to see some lows in the furthest outlying areas touch the upr 40s next weekend. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
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A cold front will pass through the area late tonight, then stall nearby on Saturday. Cold front in eastern PA is expected to push through the metro terminals between 08z and 12z. There could be an isold shower accompanying its passage but coverage too limited to include in forecast. Generally expect MVFR to locally IFR to return to the terminals by 05Z and remain until the winds shift to the W/NW late tonight. Timing in TAFs could be +/- 1-2 hours. VFR then returns W to E early Sat morning. Seabreezes expected at coastal terminal during the aftn. .OUTLOOK FOR 00Z SUNDAY THROUGH WEDNESDAY... .Saturday Night-Monday...VFR. .Tuesday...Isolated showers and thunderstorms possible with MVFR or lower conditions,otherwise VFR. .Wednesday...Scattered showers and thunderstorms with MVFR possible. Gusty southwest wind to 20 kt.
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&& .MARINE... A Small Craft Advisory/SCA remains in effect across the Atlantic Ocean coastal waters through tonight as a cold front approaches. Heavy showers and TSTMs are likely. Areas of dense fog are possible until sunrise. Weather conditions improve with the passage of a cold front Saturday morning as winds and seas fall below SCA levels. Winds and seas will increase ahead of a cold frontal passage late Tuesday and Wednesday. Seas on the ocean may linger aoa 5 ft Wed ngt behind the front. Winds and seas thereafter are progged to remain blw sca lvls. && .HYDROLOGY... A few spotty showers are possible tonight ahead of a cold front but are not expected to pose a risk of flash flooding. Impacts from potential showers and thunderstorms Tuesday into Wednesday are uncertain at this point. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 AM EDT Saturday for ANZ350-353- 355. && $$

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