Area Forecast Discussion
Issued by NWS Upton, NY

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720 FXUS61 KOKX 161341 AFDOKX Area Forecast Discussion National Weather Service New York NY 941 AM EDT Wed Aug 16 2017 .SYNOPSIS... High pressure builds in today and moves offshore on Thursday. A warm front, associated with low pressure over the Great Lakes, will then approach Thursday night, and move through on Friday. A slow moving cold front will approach from the west on Friday, and move across on Saturday. High pressure will then build in the region for the start of the new work week, and pass off the coast on Tuesday as a cold front approaches from the northwest. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Fog has burned off across the area. Expect quiet conditions across the area. Minor update to temperatures and dewpoints to reflect current conditions otherwise, no significant changes to the forecast. Looking at a mostly sunny day with a drying downslope NW flow, though immediate south facing coastal areas may still see a late day sea breeze. GFS/NAM differ on depth of mixing for today, but taking a compromise and adding 2-3 degrees this afternoon for downslope flow, expect high temps around 90 just west of NYC, upper 80s in the rest of the city and immediate suburbs, and mid 80s elsewhere. Afternoon dewpoints falling off to 60-65 should keep max heat index values just below 90. A high rip current risk will continue today for the ocean beaches as the largest swells from distant Hurricane Gert arrive. For details on Gert, please refer to National Hurricane Center products. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... A dry and tranquil night is in store for tonight with high pressure remaining in control. Lows will be in the 60s in most coastal locations, and mid/upper 50s inland and in the Long Island Pine Barrens region. Have sided with a slower model trend with an approaching frontal system, with upper ridging still to the west even by late day Thu. Have therefore kept daytime Thu mostly sunny and dry, with highs 80-85. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... With upper ridging remaining to the west of the region early Thursday night, an upper shortwave and surface warm front will be slower to affect the area, and as a result have delayed the onset of precipitation until after 00Z Friday, and then with only slight chance probabilities coming into the far western zones. Also, with the surface low remaining well to the west, then warm front will remains well to the southwest with little forcing across the region through 06Z Friday. And with little CAPE will have mention of showers but not thunder. Portions of the area become warm sectored Saturday, mainly inland, as the warm front moves through the region during the day. A supporting shortwave rotates through a longwave trough to the west and north during Friday into Friday night, and the surface low tracks north of the Great Lakes. Probabilities for precip increase as the cold front moves into the warm and unstable air mass later Friday and Friday, with likely probabilities. At this time CAPE is several hundred J/KG and will mention a chance of thunder. The surface cold front moves east 09Z to 15Z Saturday. However, there will be another shortwave rotating into the longwave trough, and the probability of precipitation remains until toward 12Z Sunday. On Sunday the upper flow becomes more zonal as weak ridging builds. The northern stream remains progressive and the next shortwave approaches for late Tuesday and Tuesday night. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... High pressure builds in today with VFR. NW winds increasing to around 10 kt. Winds should prevail north of 310 magnetic most of the day. Occasional gusts to mid teens possible this afternoon. Afternoon sea breezes expected for KJFK/KISP/KBDR/KGON. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/ KJFK TAF Comments: Timing of sea breeze shift may be off 1-2 hours. The afternoon KJFK haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KLGA TAF Comments: Chance that sea breeze moves through and shifts winds SW near 22-23z. The afternoon KLGA haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KEWR TAF Comments: Slight chance that winds back SW-S for a few hours starting near 22-23z. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Tempo 5sm vsby thru 13z might not occur with VFR prevailing instead. Slight chance that winds back SW-S for a few hours starting at around 23z. KHPN TAF Comments: No unscheduled amendments expected. KISP TAF Comments: Timing of sea breeze may be off 1-2 hours. Also a chance that sea breeze doesn`t pass through with winds remaining NW all day. .OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY... .Thursday...VFR. Afternoon sea breezes. .Thursday night through Saturday night...MVFR or lower flight cat possible in showers/tstms. .Sunday...VFR. && .MARINE... Long period southerly swells from Hurricane Gert should peak at 5-7 ft today, then slowly subside tonight into Thu as the hurricane races out into the open Atlantic per NHC forecast. Have extended the ocean SCA for hazardous seas until 2 AM Thu west, and 8 AM east. Thursday night winds and seas will remain below advisory levels as a cold front approaches from the west. A southerly flow ahead of the front will increase during Friday, and wind gusts along the Jersey shore to west of Fire Island Inlet may reach advisory levels late in the day into Friday evening. Seas should remain below small craft levels. Once a cold front crosses the waters Saturday winds shift to the west and northwest as high pressure builds over the waters. Winds and seas will remain below small craft levels Saturday and Sunday. && .HYDROLOGY... A slow-moving frontal system may bring periods of heavy rainfall Friday into Saturday, with 1/2 to 3/4 inch QPF. Hydrologic impacts are not expected at this time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...High Rip Current Risk until 9 PM EDT this evening for NYZ075- 080-081-178-179. NJ...None. MARINE...Small Craft Advisory for hazardous seas until 2 AM EDT Thursday for ANZ353-355. Small Craft Advisory for hazardous seas until 8 AM EDT Thursday for ANZ350. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.