Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 220118 AFDOKX Area Forecast Discussion National Weather Service New York NY 918 PM EDT Wed Jun 21 2017 .SYNOPSIS... A cold front moves through early tonight, followed by high pressure late tonight and Thursday. A warm front approaches Thursday night and moves through early Friday. A cold front moves through Saturday morning with a wave of low pressure passing south of the region Saturday night into Sunday morning. Another cold front approaches late Sunday night and moves through Monday. High pressure from the southwest moves in on Tuesday with a trough of low pressure approaching from the northwest late on Tuesday. High pressure then settles over the region on Wednesday. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... A shortwave was moving through the eastern portion of the region, and will be east by 06Z. With the stabilization of the atmosphere with the loss of daytime heating, showers and thunderstorms have dissipated, with just a few showers over the ocean waters south of Long Island. A cold passes through later tonight, by 06Z, and with diminishing moisture, will go with a dry forecast with its passage. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... 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. There is a moderate risk for the development of rip currents at the ocean beaches Thursday. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... 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 moisture from Cindy gets this far north. New ECMWF has now come more in line with GFS from 12z in bringing moisture further 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 reflection 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. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... A cold front continues to push across the area this evening, followed by weak high pressure building over the area on Thursday. VFR through the TAF period. Winds subside through 02Z, becoming light and variable around midnight. Seabreezes develop at coastal terminals late Thursday morning/early Thursday afternoon. A NE flow off Long Island sound at KLGA will occur until 17z or so, then seabreeze should reach the terminal. 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: Seabreeze timing tomorrow could be off by an hour or two. KLGA TAF Comments: Seabreeze timing tomorrow could be off by an hour or two. KEWR TAF Comments: Seabreeze timing tomorrow could be off by an hour or two. KTEB TAF Comments: Seabreeze timing tomorrow could be off by an hour or two. KHPN TAF Comments: Seabreeze timing tomorrow could be off by an hour or two. KISP TAF Comments: Seabreeze timing tomorrow could be off by an hour or two. .OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY... .Thursday night-Friday night...Chance MVFR or lower in 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. && .MARINE... Winds and seas on the ocean have fallen below small craft advisory levels and the advisory has been cancelled. A cold front moves through late tonight and only a few showers will remain until the passage of the front. High pressure builds into the waters late tonight. Tranquil conditions expected 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. && .HYDROLOGY... No flooding impacts anticipated through Sunday. && .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... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JC/JE/Fig NEAR TERM...JC/MET SHORT TERM...JC LONG TERM...JE/Fig AVIATION...BC/Maloit MARINE...JC/JE/Fig/MET HYDROLOGY...JC/JE/Fig TIDES/COASTAL FLOODING... EQUIPMENT...

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