Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 212134 AFDOKX Area Forecast Discussion National Weather Service New York NY 534 PM EDT Mon May 21 2018 .SYNOPSIS... High pressure builds across the region today and moves off the southern New England coast tonight. A warm front will lift through Tuesday afternoon followed by a cold front late Tuesday night into Wednesday morning. High pressure returns behind the frontal passage and remains through Saturday. Another frontal system impacts the area on Sunday and Monday. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Surface high pressure will be situated off the Northeast Coast at the start of this time frame, with a warm front approaching from the southwest. Much of tonight should remain dry, with some light rain showers moving in for portions of Northeast New Jersey and Lower Hudson Valley late tonight, towards daybreak on Tuesday. 12Z NAM is hinting at an area of stratus developing south of Long Island, moving northward over much of Long Island by 8 am Tuesday, which then quickly burns off after some diabatic heating Tuesday morning. NARRE shows only a 10-20% chance of fog development. Will leave fog out for now, with just increasing clouds for tonight. Temperatures will be slightly above normal with a light southerly flow and increasing cloud coverage. However, if cloud cover increases faster than expected, slightly warmer temperatures are possible. Right now, looking at lows in the 50s for much of the area, with upper 50s in parts of the New York City metro area. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/... Warm front continues its approach Tuesday. Along this boundary, a weak area of low pressure with an associated upper level short wave develops over the Ohio Valley/Great Lakes region and heads east into central and northern New York Tuesday afternoon and evening. Much of the heavier precipitation therefore should stay north of the area, with generally light overrunning precipitation for our area in association with the approach of the warm front. The warm front may have a tough time making it north of the tri-state during the day Tuesday, not lifting north until Tuesday night. Elevated instability may spark off some thunderstorms, but nothing severe is expected at this time. Locally heavy rain may accompany any thunderstorm, with PWATS 1.50- 1.75 inches (1 to 2 standard deviations above normal, SPC Sounding Climatology Page shows this falls in higher than the 90th percentile. Bottom line is that there could be isolated locations that receive over an inch in association with thunderstorms) However, amounts should average 0.25-0.50". Cold front quickly moves through thereafter, with the front through most, if not all the area by 8 am Wednesday. Showers and isolated thunderstorms will accompany the front, with chances for precipitation decreasing late Tuesday night, generally after 2 am. As for temperatures, clouds and rain will limit highs on Tuesday to the upper 60s to around 70, with cooler reading along the immediate shore. Overnight lows Tuesday night into Wednesday will run slightly above normal once again. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... The cold front will be moving east of the tri-state area Wednesday morning, with still a low chance of a shower mainly SE of the Lower Hudson Valley. Cold air advection behind the front will be weak, and with a mostly sunny afternoon, high temperatures will be above normal with most areas ranging from the mid 70s to lower 80s. High pressure then passes through the region on Thursday and remains in control on Friday. Dry weather continues both days with highs a couple degrees above normal on Thursday, and then warming up even more on Friday. There remains some uncertainty for the holiday weekend as global models and ensembles disagree on the surface features that would impact our weather. Have gone closer to WPC/ECMWF depiction of a cold front dropping down from the north on Saturday and perhaps stalling over us at some point on Sunday, remaining in the vicinity into Monday. Chances of showers and thunderstorms will be present all 3 days, but for now have the overall lowest chances during Saturday. && .AVIATION /22Z MONDAY THROUGH SATURDAY/... High pressure moves off the coast of New England tonight. A warm front approaches Tuesday. VFR through tonight and Tuesday morning. The chances for MVFR increase Tuesday morning, becoming likely Tuesday afternoon as rain showers develop. Southerly sea breezes around 10 kt will continue for most terminals through early evening. Winds decrease tonight to near 5 kt and become more easterly, returning to 5-10 kt Tuesday. ...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: No unscheduled amendments expected. The afternoon KJFK haze potential forecast is GREEN, which implies slant range visibility P6SM outside of cloud. KLGA TAF Comments: No unscheduled amendments expected. The afternoon KLGA haze potential forecast is GREEN, which implies slant range visibility P6SM outside of cloud. KEWR TAF Comments: No unscheduled amendments expected. The afternoon KEWR haze potential forecast is GREEN, which implies slant range visibility P6SM outside of cloud. KTEB TAF Comments: No unscheduled amendments expected. KHPN TAF Comments: No unscheduled amendments expected. KISP TAF Comments: No unscheduled amendments expected. .OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY... .Tuesday afternoon/night...MVFR in any showers, possible IFR. An isolated thunderstorm is also possible. .Wednesday morning...A slight chance of showers with MVFR possible for most terminals. .Wednesday afternoon-Thursday night...VFR. .Friday-Friday night...VFR. SW winds 10-15 kt with gusts up to 20 kt through early evening. .Saturday...Mainly VFR. && .MARINE... Winds and seas should continue to remain below advisory criteria through the rest of the forecast period. There is a low chance however for Friday into Saturday when there could be gusts close to 25 kt and seas up to 5 ft. Winds and seas should continue to remain below advisory criteria through the rest of the forecast period. There is a low chance however for Friday into Saturday when there could be gusts close to 25 kt and seas up to 5 ft. && .HYDROLOGY... Between 1/4 and 1/2 of basin avg QPF is expected with the frontal system Tue into Wed. Other than some isolated nuisance ponding with any heavy rain from tstms late Tue aftn/eve. No hydrologic impacts are expected through the week. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JC/JP NEAR TERM...JP SHORT TERM...JP LONG TERM...JC AVIATION...JM/DS MARINE...JC/JP HYDROLOGY...JC/JP

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