Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 221758 AFDOKX Area Forecast Discussion National Weather Service New York NY 158 PM EDT SUN MAY 22 2016 .SYNOPSIS... Low pressure will track east of Cape Cod today...then dissipate near Nova Scotia on Monday. Another weak low will pass near the region on Tuesday. High pressure will then briefly follow for Wednesday and Thursday with a frontal system approaching from the northwest late in the week. && .NEAR TERM /THROUGH TONIGHT/...
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Minor changes made to the forecast. Clouds are diminishing over eastern sections of the area, with stratocumulus developing as the mid and upper level clouds depart and the sun allows for afternoon heating. So, decreased cloudiness somewhat out east. Best chances for showers continues to be north and west of New York City, with dry conditions expected for the rest of the region for the remainder of the afternoon. Upr low over cntrl PA continues to inch towards the cwa this mrng. Area of light rainfall from nern NJ thru the city into CT will slowly slide ewd as a result. The low pres sys is way out over the Atlantic...so the pcpn this mrng will be due to positive vorticity advection increasing with height squeezing out residual moisture in the region. This seems to be the reason there is a bit more lgt rain and even dz being reported across the s fork of Long Island into Block Island...where there is some deeper bl/llvl moisture. The rain should become more showery in nature today with the upr low over the ern seaboard. Best instability across the interior and this lines up with the best mid lvl moisture...so highest chances for rain in those areas. The ern portion of the cwa close to the h7 low per the model progs so more mid lvl dry air. Instability drops tngt aft sunset...so the models suggest pcpn will rapidly dry out across the cwa. This consensus was followed for the fcst...although any stronger activity embedded in the flow could maintain overnight and produce a few surprise shwrs in the area. The statistical models were in good agreement today...so used a blend of the MET/MAV for temps.
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&& .SHORT TERM /MONDAY/... Good model agreement that the main h5 low sets up near Hatteras in the mrng...then drifts newd over the Atlantic during the day. Mid lvl moisture is limited...but ely flow develops late which should increase pws to over an inch per the GFS. The best chances for rain may still though hold off in most areas til the eve because of this initial lack of moisture. Warmer temps however across the interior could offset the lack of moisture and provide a net gain in instability...allowing for better rain chances during the day. Pops highest west of the Hudson for that reason. Temps close to guidance which again was in good agreement. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Global models continue to slow down with the progress of an upper trough over the Eastern U.S. at the start of the week. A closed low at the base of the trof over the Mid Atlantic states will lift slowly north into Tue, and then northeast Tue night into Wed. There are some discrepancies amongst the guidance with how quickly this feature lifts out, with the operational GFS being the slowest of the solutions. The interaction with a northern branch trof moving across Hudson Bay appears to be the key, with the magnitude of this feature varying. A model consensus approach seems to be best here with the differences being rather small for this juncture in time. Upper level ridging then expands across the area for the second half of the week with very warm conditions to ensue. In addition, the Sub tropical high over the western Atlantic begins to expand west toward the East Coast at the close of the period. This will allow for a more humid SW flow to develop around the periphery of the high. As for any rain, the best chance looks to be Mon eve into Tue with the approach of the upper low. The GFS is the deepest, farthest west, and slowest with the sfc low. Model consensus is for a weaker and faster low, thus will keep rain chances at around 50 percent at this time. There is general agreement for up to a few tenths of an inch across the area. There could even be some isolated thunderstorms Tue aft/eve due to steepening lapse rates with the upper trof overhead. It becomes much more sketchy at the end of the week with ridging aloft and likely capping. A frontal system approaches from the NW, but will likely struggle reaching the area. Chance of convection at this time is low. Near seasonable temps at the onset of the period will become unseasonably warm from mid week into the weekend with many locations away from the coast getting into the lower 80s, possibly warmer. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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Low pressure well to the east departs and weakens into tonight. Another low will approach from the south Monday. VFR conditions this afternoon and into tonight. Winds from the NE will give way to cstl seabreezes, timing dependent on site location. By evening, winds lighten. Patchy fog cannot be completely ruled out for isolated mvfr visibility, but not included in most forecasts at this time. Winds will be from the north/northeast Monday morning. .OUTLOOK FOR 18Z Monday through Friday... .Monday afternoon...VFR...with possible shower for KSWF. .Monday night-Tuesday...VFR, then good chance for showers and possible thunderstorms late Monday night and Tuesday. Sub-VFR in any showers/thunderstorms. .Wednesday-Thursday...VFR. Except sub-VFR in possible scattered showers/thunderstorms Thursday night into Friday.
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&& .MARINE... Sca conditions will develop on the ocean today and subside tngt. Winds may be mrgnl...but seas will build to at least 5-6ft. Seas at Hudson Canyon were at 9ft. Elsewhere...winds blw sca lvls. 5 ft seas develop again on the ocean Mon ngt as another low passes near the waters. Winds and seas will subside Tue night into Wed with high pressure building across the waters. && .HYDROLOGY... Less than a 1/4 inch of rainfall is expected today. Showers Mon afternoon into Tue will bring potentially a few tenths at a time where they do occur. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ350-353-355. && $$ SYNOPSIS...JMC/DW NEAR TERM...JP SHORT TERM...JMC LONG TERM...DW AVIATION...PW MARINE...JMC/DW HYDROLOGY...JMC/DW

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