Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 201747 AFDOKX Area Forecast Discussion National Weather Service New York NY 147 PM EDT Thu Oct 20 2016 .SYNOPSIS... A warm front will slowly approach from the south this afternoon and tonight. 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/... Warm advection has resulted in scattered showers tracking NE across eastern PA. Easterly flow veers to the SE as the front begins to return north this afternoon. Lower clouds are moving in from the south.once these clouds settle in, temperatures will likely remain steady through the afternoon. Could see some light rain or drizzle locally this afternoon. Temps hold around 70 which is still 5-8 degrees above normal, but 15 degrees cooler than Wednesday. Winds will be gusty from the east. && .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 in 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 /18Z THURSDAY THROUGH TUESDAY/... A warm front to the south will move northward towards the area into this evening, and gradually pass north overnight. Conditions gradually deteriorate heading into the evening. Good model agreement with visibility and ceilings leading to a period of LIFR conditions for all TAF sites starting around 06z. Keeping drizzle in the forecast for the overnight ahead of the warm front. Expecting temporary improvement in conditions towards mid-morning on Friday, before a possible return to IFR/LIFR conditions during the day tomorrow in any developing showers. Easterly winds expecting to remain gusty ahead of the front, and diminish this evening after the loss of daytime heating and as the gradient relaxes. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/ KJFK TAF Comments: Gusty easterly winds diminishing this evening. LIFR conditions may develop earlier than forecast. KLGA TAF Comments: LIFR conditions may develop earlier than forecast. KEWR TAF Comments: Gusty easterly winds diminishing this evening. LIFR conditions may develop earlier than forecast. KTEB TAF Comments: Gusty easterly winds diminishing this evening. LIFR conditions may develop earlier than forecast. KHPN TAF Comments: Gusty easterly winds diminishing this evening. LIFR conditions may develop earlier than forecast. KISP TAF Comments: Gusty easterly winds diminishing this evening. LIFR conditions may develop earlier than forecast. .Outlook for 18Z Friday through Tuesday... .18Z FRI...Showers with MVFR or lower conditions likely. NW winds G30-35KT developing late Friday night. .SAT... NW winds G30-35KT. Chance of MVFR early. .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. .TUE...Mainly VFR. NW winds G20KT. && .MARINE... SCA now in effect for ANZ350, eastern Ocean waters, through midnight. East winds, as expected, are increasing, and seas are up to 4 ft, with 5 footers likely. Otherwise, winds should remain just below SCA levels this afternoon elsewhere with gusts into the lower 20 KT range. Ocean seas west of Moriches Inlet NY are expected to remain under 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 the western Long Island Sound and for the south shore of Nassau County. 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...Small Craft Advisory until midnight EDT tonight for ANZ350. && $$ SYNOPSIS...Tongue/DW NEAR TERM...Tongue/DW/PW SHORT TERM...Tongue LONG TERM...DW AVIATION...CB/IRD MARINE...Tongue/DW/PW 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.