Area Forecast Discussion
Issued by NWS Upton, NY

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739 FXUS61 KOKX 200901 AFDOKX Area Forecast Discussion National Weather Service New York NY 501 AM EDT Thu Oct 20 2016 .SYNOPSIS... A warm front will slowly approach from the south today. A Cold front will move through late Friday with showers likely. Deepening low pressure tracks across the Northeast Friday night into Saturday and then becomes nearly stationary across Eastern Canada Saturday night into Sunday. A weak Alberta clipper low and associated cold front will move through Sunday night into Monday. High pressure builds in through mid week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Easterly flow veers to the SE as the front start to return north this afternoon. High clouds filter in from the west this morning, though the bulk of these clouds pass to the north as the upper flow backs to SW. PCPN over Western PA as of 07Z will track north of the local area. Lower status starts to advect in by late afternoon and there may be some sprinkles or even light RA around. This based on forecast soundings and NARRE-TL. Temps today max out in the 65-70 degree range which is still 5-8 degrees above normal - but 15 degrees cooler than Wednesday. Winds pick up some early this afternoon as they start to veer SE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... Available NWP (NCEP Deterministic with 50% of the GEFS members and the CMC and ECMWF Deterministic Runs) is fairly good agreement with low pressure at the triple point over SE New England by 00Z Saturday. It remains to be seen how the subtropical low over the Bahamas interacts with the baroclinic system, but am not currently forecasting a lot on the QPF...around 1/2". POPs for Friday remain unchanged in the likely range. Temps for Friday are a bit of a challenge, but have favored warmer the warmer GFS and ECMWF MOS based on trends and not expecting continuous PCPN. This results in temps reaching the lower to mid 70s. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... There is better agreement amongst the global models in the closing off of an upper low as an amplifying negatively tilted trough moves into the area Friday night into Saturday. 00Z ECMWF is still somewhat slower than operational GFS while the GGEM has become the slowest of the operational runs. This uncertainty will be accounted for in gradually diminishing rain chances during the day Saturday. In addition, there are differences in the axis of the heaviest rain with both the warm conveyor belt rain to the east of the low track and with the frontogenetic forcing to the northwest. Based on a low track to the east of the area, discounting heavy rain band in warm sector across Eastern LI/SE CT Friday night as noted by ECMWF. That being said, should the upper low cutoff a bit farther west, this solution is plausible and will have to be watched in subsequent model run. Strong cold advection and gusty NW winds will ensue on the backside of the deepening upper low Saturday and continues right through the weekend as the low occludes and becomes nearly stationary across Eastern Canada on Sunday. By Sunday night, another shortwave moves around the backside of the cutoff, and low pressure and associated cold front push through later Sunday night into Monday. There is a low chance of showers with this features, but winds turn to the NW and increase once again. High pressure follows for the mid week period. Much of the time period will be marked by unseasonably cool conditions with the exception of Monday, which is forecast to be near normal, before cooler air filters back in behind the front for Tuesday and Wednesday. && .AVIATION /09Z THURSDAY THROUGH MONDAY/...
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A frontal boundary to the south will move north towards the area as a warm front today...and gradually pass north tonight. Increasing e winds after daybreak...10 to 15 kt for most terminals with gusts to 20 kt. Sustained winds of 15 to 20 kt possible at KBDR and KLGA. Winds and gusts should subside this evening...and begin to veer to the se tonight as the warm front moves through. VFR conditions this morning...expected to gradually deteriorate through the afternoon. MVFR stratus development likely late morning into the afternoon...falling to ifr by late afternoon/evening. Increasing chance for light rain/drizzle this afternoon into evening. VSBY should be VFR for much of the day...but then falling to mvfr/ifr or possibly lower this evening in -RADZ ahead of warm front. Warm front gradually works north tonight. This may allow for a temporary improvement in conditions overnight in its wake...particularly for coastal terminals. ...NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP://WWW.WEATHER.GOV/ZNY/N90 (LOWER CASE) KJFK FCSTER COMMENTS: MVFR CONDITIONS MAY DEVELOP 1 TO 2 HRS LATER THAN FORECAST. WINDS GUSTS TO 20 KT DEVELOPING AFTER 14Z. KLGA FCSTER COMMENTS: MVFR CONDITIONS MAY DEVELOP 1 TO 2 HRS LATER THAN FORECAST. SUSTAINED 15 TO 20 KT ne WINDS POSSIBLE AFTER 14Z. KEWR FCSTER COMMENTS: MVFR CONDITIONS MAY DEVELOP 1 TO 2 HRS LATER THAN FORECAST. WINDS GUSTS TO 20 KT DEVELOPING AFTER 14Z. The afternoon KEWR haze potential forecast is YELLOW...which implies slant range visibility 4-6SM outside of cloud. KTEB FCSTER COMMENTS: MVFR CONDITIONS MAY DEVELOP 1 TO 2 HRS LATER THAN FORECAST. WINDS GUSTS TO 20 KT DEVELOPING AFTER 14Z. KHPN FCSTER COMMENTS: MVFR CONDITIONS MAY DEVELOP 1 TO 2 HRS LATER THAN FORECAST. WINDS GUSTS TO 20 KT DEVELOPING AFTER 14Z. KISP FCSTER COMMENTS: MVFR CONDITIONS MAY DEVELOP 1 TO 2 HRS LATER THAN FORECAST. WINDS GUSTS TO 20 KT DEVELOPING AFTER 14Z. .Outlook for 06Z Friday through Monday... .LATE TONIGHT into FRI MORNING...IFR or lower conditions in stratus/fog and showers. .FRI AFT into FRI NIGHT...Showers with MVFR or lower conditions likely. NW winds G30-35KT developing late FRI NIGHT. .SAT...Chance of showers with MVFR or lower conditions. NW winds G30-35KT. .SAT NIGHT...Mainly VFR. W winds G25KT. .SUN...VFR. W winds G30KT. .SUN NIGHT...Mainly VFR. W winds G20KT. .MON...Mainly VFR. W winds G20KT in the afternoon.
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&& .MARINE... Looks like winds with hold just below SCA levels today with gust into the lower 20 KT range and seas on the eastern ocean just below 5 FT. After a lull in winds Friday as a frontal boundary moves through. Long Term: There is the potential for W-NW gales stating Saturday and continuing through the weekend, especially on the ocean, in the wake of the frontal system and deepening low to the north. Winds should diminish later Sunday, but turn NW and increase behind a cold front Monday. Seas build and will remain rather rough through much of the period due to the gusty winds. Followed Nearshore Wave Prediction guidance, and Wave Watch III output. && .HYDROLOGY... Rainfall overnight into Friday night should average around 1/2". No hydrologic problems are expected. There after, no significant rainfall is expected through the middle of next week. && .TIDES/COASTAL FLOODING... A Coastal Flood Statement remains in effect for the south shore of Nassau County for the late morning high tide cycle. Tidal departures between 1/2 and 1 1/2 ft are expected which will cause some locations to experience brief minor tidal flooding of the more vulnerable shore roads and/or adjacent properties. The potential also remains for minor coastal flooding ahead of an approaching frontal system with the Fri afternoon high tide cycles. Generally 1-2 ft departures are needed for minor flooding. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...Tongue/DW NEAR TERM...Tongue SHORT TERM...Tongue LONG TERM...DW AVIATION...NV MARINE...Tongue/DW HYDROLOGY...Tongue/DW TIDES/COASTAL FLOODING... is the U.S. government's official web portal to all federal, state and local government web resources and services.