Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 250822 AFDOKX Area Forecast Discussion National Weather Service New York NY 422 AM EDT Thu May 25 2017 .SYNOPSIS...
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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.
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&& .NEAR TERM /THROUGH FRIDAY/...
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The rain shield had made it past Trenton at 330 am. Radar has the rain moving nwd at 29kt. This takes it to NYC by 5 am. The models are supported by the radar and stlt presentation, so little change was made to the fcst. Rain can be expected this mrng, mainly moderate in intensity, with perhaps an isold embedded tstm. Chances appear to be best across ern LI where theta-e advection will be the strongest. Lightning strikes over the Atlantic appear to support this, however, the model time heights show deep lift across the entire cwa, so the low chances for tstms have been retained for the entire area. Ely winds will pick up this aftn as the pres drops and a 1021 high sets up s of Labrador. The model data supports wind gusts to around 30 mph. A break in the pcpn is possible, particularly late this aftn and early eve, as the waa pcpn ends and the h5 low lags behind. When the upr low does get here tngt, the dpva is significant. Lapse rates from h85 to h4 range avg around 6.5C/km. The models all produce convective pcpn. As a result, widespread shwrs and embedded tstms are expected. The upr low reaches the Gulf of ME on Fri. This will allow for decreasing coverage and intensity of shwrs thru the day. The downslope flow could allow for clearing, especially along the coast, by the end of the day. Temps will be blw normal today, then will nudge closer on Fri as the rain ends. A blend of the guidance and raw model data was used.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
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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.
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&& .LONG TERM /MONDAY THROUGH WEDNESDAY/...
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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.
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&& .AVIATION /07Z THURSDAY THROUGH MONDAY/...
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An area of low pressure will move across the region through the TAF period. MVFR cigs continue to move across the southern terminals. Low clouds will continue to lower and thicken, becoming IFR or less everywhere by 12z. Rain overspreads the region for the morning push, and remains through about 18-21Z. Thereafter, precipitation should become more showery in nature, with some areas of drizzle in between the showers. There is a chance that visibilities fall below a mile in fog after 18z. There will also be a chance of thunder after 00z, however confidence of timing and placement of any convection too low to include in the TAFs at this time. Generally looking at an easterly wind through the period 10-15kt with gusts 20-25kt. winds lighten late. ...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: Occasional gusts could be higher than forecast. Amendments may be needed for changing flight categories. KLGA TAF Comments: Occasional gusts could be higher than forecast. Amendments may be needed for changing flight categories. KEWR TAF Comments: Occasional gusts could be higher than forecast. Amendments may be needed for changing flight categories. The afternoon KEWR haze potential forecast is YELLOW...which implies slant range visibility 4-6SM outside of cloud. KTEB TAF Comments: Occasional gusts could be higher than forecast. Amendments may be needed for changing flight categories. KHPN TAF Comments: Occasional gusts could be higher than forecast. Amendments may be needed for changing flight categories. KISP TAF Comments: Occasional gusts could be higher than forecast. Amendments may be needed for changing flight categories. .OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY... .Tonight...LIFR/IFR in rain. .Friday...MVFR/IFR possible. Chance of showers. .Saturday...VFR. .Sunday-Monday...MVFR/IFR possible in showers.
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&& .MARINE...
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E winds will increase today with SCA criteria across all the waters. Low pres will track over the area tngt, so winds will lighten blw SCA lvls. 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 blw SCA lvls for entire Memorial Day Weekend.
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&& .HYDROLOGY...
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1-1.5 inches of rain is fcst thru Fri. Locally higher amounts can be expected where tstms occur. Minor urban and poor drainage flooding is possible. Hydrologic impacts are otherwise not expected Sat-Tue.
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&& .TIDES/COASTAL FLOODING...
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A Coastal Flood Warning has been issued for south shore back bay locations of Nassau County for tonight, otherwise advisories are in place for areas adjacent to western Long Island Sound, NY Harbor, and the south shore back bays of the western Long Island. While astronomical tides are lower this morning, a strengthening easterly flow will bring the potential for localized brief minor flooding for those areas under either a warning or advisory later tonight. A statement is in effect for this morning. The primary threat for minor to moderate coastal flooding will be during the high tide cycle tonight. How quickly easterly winds begin to weaken this afternoon/evening will be key to the potential for seeing widespread versus localized moderate coastal flooding along the southern bays of NYC and Western LI. The best chance for widespread moderate coastal flooding at this time appears to be across the south shore back bays of Nassau County, where a warning is in effect. Along Western LI Sound, NY/NJ Harbor including Manhattan, and the southern bays of Suffolk County, widespread minor coastal flooding is likely with less than 1/2 ft of surge needed in many places to reach minor flood thresholds. Minor flood thresholds could briefly be touched along the eastern bays of LI and SE CT. The potential for dune erosion looks to be low and localized.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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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.
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&& $$ SYNOPSIS...JMC NEAR TERM...JMC SHORT TERM...JMC LONG TERM...JMC/Maloit AVIATION...BC MARINE...JMC HYDROLOGY...JMC TIDES/COASTAL FLOODING...DW

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