Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 181643 AFDOKX Area Forecast Discussion National Weather Service New York NY 1243 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/...
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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.
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&& .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 MONDAY/... 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 and KGON which will hold onto MVFR cigs within the next hour. Some scattered showers and thunderstorms are possible after 18z. 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 become 5-12 kt from the south/southeast. Winds 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. The afternoon KJFK haze potential forecast is YELLOW...which implies slant range visibility 4-6SM outside of cloud. KLGA TAF Comments: No unscheduled amendments are expected. The afternoon KLGA haze potential forecast is YELLOW...which implies slant range visibility 4-6SM outside of cloud. KEWR TAF Comments: The SE wind arrival time could be off 1-2 hours compared to forecast. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: S wind start time could be off by 1-2 hours compared to forecast. KHPN TAF Comments: S wind start time could be off by 1-2 hours. Expecting 3500` cigs to scatter out before 18Z. KISP TAF Comments: MVFR cigs could last to 18Z with otherwise no unscheduled amendments expected. .OUTLOOK FOR 12Z WEDNESDAY THROUGH SATURDAY... .Wednesday-Thursday...Chance of showers and thunderstorms, primarily in the late afternoon and NYC and north and west. .Friday-Saturday...VFR.
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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...BC/JM MARINE...MET/Tongue/NV HYDROLOGY...Tongue

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