Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 181814 AFDOKX Area Forecast Discussion National Weather Service New York NY 214 PM EDT Tue Jul 18 2017 .SYNOPSIS... Typical mid-summer weather through the weekend with isolated to scattered afternoon convection for the interior as temperatures run above normal. Low pressure affects the area early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Forecast on track. Convection not yet more widespread, with only the one cell moving into Orange county. With further destabilization expecting convection to develop. GOES 16 still showing rather dry atmosphere from the lower levels int the upper levels. But still expecting destabilization. Did lower probabilities somewhat, lower end chance and slight chance across the interior zones. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... More patchy fog forms, especially east overnight. And keep it dry tonight with no trough passage. More of the same for Wednesday - though warmer. About 3-4 degrees warmer for Wednesday as we reach 90 and the potential start of a heatwave for the NYC Metro. More Isolated to Scattered afternoon convection. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... A lingering weak upper trough on Wednesday will give way to an active zonal flow late week through the weekend as a anomalously strong polar low tracks through Northern Ontario/Quebec. Region appears to be in between troughs on Thursday, resulting in only a low and sparse chance of convection across interior late in the day. A weak cold front approaches Thursday Night as the first in a series of shortwaves tracks through the NE in the developing zonal flow. The evolution of the polar low will play a factor in sensible weather heading into the weekend and early next week, as well as a stationary front residing near the region. The front will be the axis for unsettled weather Fri Night through Mon in the form of MCS activity and diurnal convection as a series of shortwaves track through the region. Uncertainty exists on how close to the region this front resides and timing of shortwaves. A low predictability forecast at this point, so have stayed close to climo for diurnal convection chances. A gradual uptick in pops seems prudent Sun/Mon (consistent with previous forecast) due to lowering heights, increasing moisture, and signal for approaching PAC shortwave and low pressure system for early next week. Temperatures through Fri should be above normal (well into the 80`s to lower 90`s). Lower confidence on temp forecast for the weekend based on frontal placement and convection, but near to above seasonable temps appear likely. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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A weak front remains nearly stationary over the region through Thursday. VFR expected today at most terminals except for KISP which will hold onto MVFR cigs within the next hour. Some scattered showers and thunderstorms are possible before 23Z. VCTS in the TAFs for KSWF and KHPN where confidence is higher. Confidence too low to include any TSRA/VCTS in the TAFs at other terminals. Winds 5-12 kt from the south/southeast will diminish tonight to less than 5 kt. 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: No unscheduled amendments are expected. KLGA TAF Comments: No unscheduled amendments are expected. KEWR TAF Comments: No unscheduled amendments are expected. KTEB TAF Comments: No unscheduled amendments are expected. KHPN TAF Comments: S wind start time could be off by 1-2 hours. Expecting 3500` cigs to scatter out before 20Z. KISP TAF Comments: MVFR cigs end time could be off by an hour with otherwise no unscheduled amendments expected. .OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY... .Wednesday-Thursday...Chance of showers and thunderstorms, primarily in the late afternoon and NYC and north and west. .Friday...VFR. .Saturday...MVFR or lower possible with a chance of showers and thunderstorms. .Sunday...MVFR or lower possible with a chance of showers and thunderstorms.
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&& .MARINE... A very weak pressure gradient over the region will limit winds to 10 kt or less, and keep seas well below SCA levels through Saturday. && .HYDROLOGY... No organized rainfall is anticipated through the weekend. There is potential that slow moving afternoon summertime convection could produce highly localized flash flooding each day. A more organized weather system early next week should produce a widespread rain event, but at this time the flash flood threat remains low. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...Tongue NEAR TERM...MET SHORT TERM...Tongue LONG TERM...NV AVIATION...JM MARINE...MET/Tongue/NV HYDROLOGY...Tongue

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