Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 251825 AFDOKX Area Forecast Discussion National Weather Service New York NY 225 PM EDT Thu May 25 2017 .SYNOPSIS... Low pressure will deepen over the Mid-Atlantic today, track through the Tri-State Region tonight and into the Maritimes on Friday. A broad area of high pressures builds in for the first half of the weekend, then a slow moving frontal system will bring the potential for showers from Sunday into Tuesday. && .NEAR TERM /THROUGH FRIDAY/... Middle level drying is fast approaching from the south and west early this afternoon. The back edge of the steady rain is now moving through the NYC metro and will continue tracking northward into the early afternoon. As the middle levels dry out, we will be left with just a chance for light rain or drizzle. Some uncertainty on whether or not there will be any precipitation this afternoon, with the highest confidence in continued low clouds and areas of fog. Easterly winds will be gradually weaken this afternoon as the pressure gradient slackens, but a few gusts up to 20-25 mph possible near the coast early. Attention then turns to the H5 low, currently over the Ohio Valley and a vigorous piece of energy located across the southeast. The upper low will swing this vorticity energy towards the region tonight, with impressive DPVA aloft and steepening lapse rates in the middle levels. The models all produce convective precip. As a result, showers and embedded thunderstorms are expected overnight. The upper low reaches the Gulf of ME on Fri. This will allow for decreasing coverage and intensity of showers through the day. The downslope flow could allow for clearing, especially along the coast, by the end of the day. Temps will be below normal today, then will nudge closer on Fri as the rain ends. A blend of the guidance and raw model data was used. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... Weak ridging builds in Fri ngt and Sat which will attempt to produce fair weather. There is a suggestion of shrtwv energy swinging thru on Sat. If this materializes, isold-sct shwrs will be possible. A rainy day however is not expected attm. A broad upr lvl low then drops into the Midwest, producing sw flow aloft across the fcst area Sun. This will produce an increasing chance for shwrs, particularly Sun aftn thru Sun ngt. Temps will remain close to or blw normal thru the period. The Superblend was used. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... The upr low over the Midwest will drive a slow moving frontal sys thru the region for the beginning of the week. There is some uncertainty wrt the timing, with the ECMWF slightly faster than the GFS. Chance POPs remain in the fcst. Weak ridging builds in Tuesday, followed by more shortwaves rotating around the S Canada closed low, which has slid a bit farther E into Hudson bay/NW Ontario), Tuesday night and Wednesday - with maybe some more isolated- scattered showers. Temperatures should be within a few degrees of either side of normal Sunday-Monday night, then run above normal Tuesday- Wednesday. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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An area of low pressure will move northeast over the region tonight...and just to the northeast of the region Friday. IFR/LIFR cigs continue into tonight. Potential for LIFR visibilities this evening in dz/fog. Showers with a chance for thunderstorms between 03z and 10z. Heavy downpours are the main threat. Gradual improvement to MVFR/VFR cigs Friday morning...with quicker improvement to VFR vsby. Chance for showers. Easterly winds 10-20 kt with gusts to 25 kt this afternoon...weakening this evening. Light and variable winds tonight...becoming northwest and gusty Friday morning. 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: High confidence in IFR/LIFR cigs for evening push. IFR/LIFR vsby will be conditional with drizzle. TSRA possible between 03z and 09z. KLGA TAF Comments: High confidence in IFR/LIFR cigs for evening push. IFR/LIFR vsby will be conditional with drizzle. TSRA possible between 03z and 09z. KEWR TAF Comments: High confidence in IFR/LIFR cigs for evening push. IFR/LIFR vsby will be conditional with drizzle. TSRA possible between 03z and 08z. KTEB TAF Comments: High confidence in IFR/LIFR cigs for evening push. IFR/LIFR vsby will be conditional with drizzle. TSRA possible between 03z and 08z. KHPN TAF Comments: High confidence in LIFR conds for evening push...VLIFR possible. TSRA possible between 03z and 09z. KISP TAF Comments: High confidence in IFR/LIFR cigs for evening push. IFR/LIFR vsby will be conditional with drizzle. TSRA possible between 03z and 10z. .OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY... .Friday...W/WNW wind gusts 20 to 25 kt developing late morning and continuing into afternoon. Winds generally left of 310 magnetic. Conditions gradually improve to MVFR/VFR in the late morning to afternoon. SHRA possible. .Saturday...VFR. .Saturday Night-Monday...MVFR/IFR possible in showers. E/SE winds. .Tuesday...Improving to VFR. S/SE winds.
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&& .MARINE... E winds will gradually weaken into the afternoon. SCA conditions continue on all waters, with winds on the near shore waters falling below criteria by late this afternoon. Low pressure will track over the area tonight, so winds will lighten below SCA levels. Seas on the ocean however will remain in the 5-10 ft range thru Fri. The SCA has therefore been extended for these areas. Winds and seas currently look to remain below SCA levels for entire Memorial Day Weekend. && .HYDROLOGY... An additional 0.50 to 1.5 inches of rain is forecast through Fri. The highest amounts will likely occur across eastern Connecticut and eastern Long Island. Locally higher amounts possible where thunderstorms occur tonight. Minor urban and poor drainage flooding is possible. Hydrologic impacts are otherwise not expected Sat-Tue. && .TIDES/COASTAL FLOODING...
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A Coastal Flood Warning continues for moderate flooding potential for the south shore back bay locations of Nassau County for tonight, and advisories are in place for minor flooding potential for areas adjacent to western Long Island Sound, NY Harbor, and the south shore back bays of the western Long Island. Minor flood thresholds could briefly be touched along the eastern bays of LI and SE CT. How quickly easterly winds begin to weaken this evening will be key to the potential for seeing widespread versus localized moderate coastal flooding along the southern bays of Western LI. Less than 1/2 ft of surge is needed in many places to reach minor flood thresholds. The threat for minor coastal flooding is likely during the nighttime high tides for the southern bays of Western LI through the Memorial Day Weekend. While along western Long Island Sound, lower NY Harbor, and the southern bays of NYC minor coastal flooding is possible at those times. Beach erosion is expected with the prolonged easterly sweep...but the potential for dune erosion looks to be low and localized.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...Coastal Flood Advisory from 10 PM this evening to 1 AM EDT Friday for CTZ009-010. NY...Coastal Flood Advisory from 7 PM to 10 PM EDT this evening for NYZ074-075-178. Coastal Flood Advisory from 10 PM this evening to 1 AM EDT Friday for NYZ071-073-078-176-177. Coastal Flood Advisory from 8 PM this evening to midnight EDT tonight for NYZ080. Coastal Flood Advisory from 7 PM this evening to 1 AM EDT Friday for NYZ072. Coastal Flood Warning from 7 PM to 11 PM EDT this evening for NYZ179. NJ...Coastal Flood Advisory from 7 PM to 10 PM EDT this evening for NJZ006-106-108. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ330- 335-338-340-345. Small Craft Advisory until 6 PM EDT Friday for ANZ350-353-355. && $$ SYNOPSIS...JMC NEAR TERM...JMC/DS/DW SHORT TERM...JMC LONG TERM...JMC/Maloit AVIATION...NV MARINE...JMC HYDROLOGY...JMC TIDES/COASTAL FLOODING...

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