Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 212014 AFDOKX Area Forecast Discussion National Weather Service New York NY 414 PM EDT Wed Jun 21 2017 .SYNOPSIS...
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A cold front moves through tonight, followed by high pressure on Thursday.
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&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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Shortwave exits east early this evening, and with the loss of daytime heating, coverage of showers/TSTMs will diminish. Until then, sufficient SBCAPE, lift and shear for the potential of strong thunderstorms with the main threat being gusty winds as there`s also a relatively dry sub-cloud layer in place. A cold passes through later tonight, and with diminishing moisture, will go with a dry forecast with its passage. Low temperatures are expected to be near normal. There is a high risk for rip current development at Suffolk County ocean beaches and a moderate risk for NYC and Nassau county ocean beaches through this evening.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
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Ridging at the surface and aloft for Thursday will keep us dry. Sunshine will mix with increasing cirrus as the day progresses. 850mb temps are progged to rise to 15-16C by the end of the day. Have gone slightly above the warmer side of model guidance for high temperatures. A weak warm front will be in the vicinity Thursday night. Isentropic lift is not impressive, and most of the forecast area is progged to be in an area of NVA most of the night. Still cannot rule out an isolated shower after dark, and do not have enough confidence to completely remove chances. Will therefore keep a slight chance primarily north and west of the city.
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&& .LONG TERM /FRIDAY THROUGH THURSDAY/...
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An active northern branch of the polar jet will remain across the northern tier of the country, with the mean upper trough residing over the Northern Plains and upper Midwest through Friday, then extending into the Northeast this weekend and into the first half of next week. This will allow for several frontal systems to impact the area during this time, the first Friday into Saturday, and then another Sunday night into Monday. After a warm frontal passage Friday morning, temps should warm up well into the 80s, with lower 80s closer to the coast, with dewpoints increasing to the upper 60s to lower 70s. A few tstms are possible in the warm sector, but timing/areal coverage are in question, as models generally indicate better instability for Friday afternoon and evening, and disagree on timing of the approach of a southern branch mid level shortwave trough well in advance of the remnants of Tropical Storm Cindy to produce lift. This first front approaches Friday night and looks to stall over the area, with another chance for showers/tstms on Saturday. Areal coverage will depend on the northward extent of any residual energy from the remnants of Cindy to provide lift. A rather low confidence forecast in terms of how much mositure from Cindy gets this far north. New ECMWF has now come more in line with GFS from 12z in bringing moisture futher north, with new Canadian shearing moisture out to our south. Not quite ready to totally buy into more northern solution at this time. Instability looks more limited with the second frontal passage Sunday night into Monday, and moisture will be more lacking, so have only mentioned chance of showers and a slight chance of thunderstorms. A surface relection just south of the region hinted by some of the modeling would result in more of a stratiform precipitation for Monday. Models are differing here on the amplification and timing of the next shortwave rounding the mean upper trough. Temps will run near to slightly above average through the weekend, then fall slightly below seasonable levels early next week. Temperatures will then climb to slightly above average late in the period.
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&& .AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
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A cold front moves cross the area this afternoon and early this evening, followed by weak high pressure building over the area into Thursday afternoon. Highly likely VFR through the TAF period. A brief period of MVFR is possible this afternoon/early this evening with any stronger convection at any given terminal. Still appears there will be isolated to scattered showers and thunderstorms at area terminals through 22-02z from W to E. Confidence at this time is only sufficient to carry a VCTS in the TAFS. W-SW winds, with seabreeze at KJFK/CT. Gusts this afternoon mainly 15-20kt with peak gusts 25-30kt mainly at coastal terminals. Higher gusts are possible with any stronger convection. Winds subside after 23 to 01z, then become light and variable throughout by around midnight. Seabreezes develop at coastal terminals late Thursday morning/early Thursday afternoon, with a NE flow off Long Island sound at KLGA. At KSWF/KHPN/KTEB should see a SW-W flow at under 10 kt by around midday Thursday. 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: S-SSW seabreeze gusting to around 20KT develop around 21z with isolated gusts up to 25KT possible. Low chance of a shower/tsra between 20z and 23z, with G35-40KT possible in any stronger storm. KLGA TAF Comments: WSW winds gusting to around 20KT with isolated gusts up to 25KT possible. Low chance of a shower/tsra between 20z and 23z, with G35-40KT possible in any stronger storm. KEWR TAF Comments: WSW winds gusting to around 20KT with isolated gusts up to 25KT possible. Low chance of a shower/tsra between 20z and 23z, with G35-40KT possible in any stronger storm. KTEB TAF Comments: WSW winds gusting to 15-20KT with isolated gusts up to 25KT possible. Low chance of a shower/tsra between 20z and 23z, with G35-40KT possible in any stronger storm. KHPN TAF Comments: W winds gusting to around 15KT around 20-23Z, with isolated gusts up to 20-25KT possible. Low chance of a shower/tsra between 20z and 23z, with G35-40KT possible in any stronger storm. KISP TAF Comments: SW winds around 10KT. Isolated gusts up to 20 kt possible. Low chance of a shower/tsra between 22z and 01z. .OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY... .Thursday afternoon...VFR, with seabreezes likely. .Thursday night-Friday night...Chance MVFR or lower and of mainly afternoon showers/thunderstorms. SW winds G15-20KT possible Friday afternoon. .Saturday...CHC early -shra/MVFR, otherwise VFR. NW winds G15-20KT possible. .Saturday night-Sunday...VFR. .Sunday night-Monday. MVFR or lower possible. SW winds G15-20kt possible Monday.
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&& .MARINE...
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SCA on all but the ocean waters east of Fire Island Inlet has been cancelled. 25kt gusts have not materialized, and although occasional gusts this high will be possible into early evening, thinking is that the coverage, probability and frequency of such gusts are not enough to keep the SCA going at this point. Looks like 5 ft seas can still occur into this evening east of Fire Island Inlet given sustained winds and direction, so will leave the SCA here unchanged. Tranquil conditions then follow late tonight through Thursday night as high pressure builds in, then shifts offshore with a relatively weak pressure gradient. SCA conditions will be possible on the ocean Friday night into Saturday morning as S-SW flow increases to 15 to 20 kt with the approach of a cold front, and building seas to near 5 ft. Seas will then subside to below SCA later in the weekend and into Monday.
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&& .HYDROLOGY...
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Iso/sct thunderstorms into this evening should move quickly enough to preclude flooding impacts. No flooding impacts are then are anticipated through Sunday.
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&& .TIDES/COASTAL FLOODING... With the approach of a new moon, occurring Friday evening, astronomical tides will be running very high, especially during the high tide cycles Thursday, Friday, Saturday evening. Less than 1 ft of surge is needed for minor flooding...and in some cases less then 1/2 ft...during these evening high tide cycles. The expected S/SW flow is not favorable for surge build-up, but southerly swells and a running anomaly will likely be enough for minor coastal flooding along the south shore back bays of Nassau with each evening tidal cycle. Brief and localized minor coastal flooding will also be possible in Jamaica Bay and Western Long Island Sound during this time. && .EQUIPMENT... KOKX weather radar is scheduled for maintenance starting this Friday June 23rd for a period of 3 days. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...High Rip Current Risk until 9 PM EDT this evening for NYZ080- 081. NJ...None. MARINE...Small Craft Advisory until 2 AM EDT Thursday for ANZ350-353.
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&& $$ SYNOPSIS...JC/JE/Fig NEAR TERM...JC SHORT TERM...JC LONG TERM...JE/Fig AVIATION...Maloit MARINE...JC/JE/Fig HYDROLOGY...JC/JE/Fig TIDES/COASTAL FLOODING... EQUIPMENT...

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