Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 300641 AFDOKX Area Forecast Discussion National Weather Service New York NY 241 AM EDT THU JUN 30 2016 .SYNOPSIS... A slow moving cold front will exit to the east overnight, followed by high pressure on Thursday. Low pressure will then develop over the Mid Atlantic states Thursday night, and its associated warm front will approach on Friday. A cold front will move across Friday night, followed by high pressure building from the upper Midwest from Saturday through Monday. Another low will approach next Tuesday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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Cold front now just east of LI and SE CT with drier air filtering in on a light NW flow. Low temps should be within a few degrees of either side of average.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... Forecast is on track, only minor changes made to reflect current conditions. Mid level shortwave ridging will slide across on Thursday, with associated subsidence keeping things dry and relatively cloud free, except for maybe some afternoon cirrus. Highs on Thursday were based on a blend of MAV/MET/ECS guidance, NAM 2-meter temperatures and a mix down from 900-775 hPa per BUFKIT soundings. Highs should be near to a few degrees above normal. Weak shortwaves at 700-500 hPa help bring a wave of low pressure up a stationary front over the Mid-Atlantic states Thursday night. It appears that should have sufficient low level warm advection to warrant slight chance pops over most of the area mainly during the overnight hours. A blend of MET/ECS/MAV guidance and NAM 2-meter temperatures was used for lows Thursday night, with readings forecast to be a few to upwards of around 5 degrees above normal. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... The next shortwave that will be the focus to start the long term is currently in Manitoba and Ontario. The shortwave pivots to the Northeast Friday morning and becomes more negatively tilted throughout the day and into Friday night. The left front quad of the associated upper level jet streak is forecast to move in Friday night with the rest of the jet streak moving across through the remainder of the weekend. The low level jet increases also Friday night. This will aid lift by Friday night for precipitation. A warm front approaches Friday but may only cross through a part of the region or may just stay south of the region. A cold front then approaches from the west, crossing the region late Friday night. In terms of thunderstorms, instability as diagnosed by surface CAPE increases to approximately 500-1500 J/kg during the day, highest west of NYC, and then decreases and becomes more situated at the coastlines Friday night. So the forecast is for a chance of showers and thunderstorms Friday and Friday night. For the weekend into Monday, the shortwave axis will be moving east of the region, leaving the region on the backside of this shortwave trough. High pressure at the surface from the Upper Midwest builds in with more of westerly flow developing. The westerly flow taking place will allow for drier air to advect in with more stable conditions developing. Dry conditions are forecast for much of the weekend into Monday as well as much of Monday night. There will be rising heights Sunday and Monday but high pressure at the surface will eventually weaken. This will allow for more of a southerly component to the wind Sunday afternoon and Monday with more sea breeze influence. The next shortwave approaches for Tuesday and Tuesday night with a low pressure area approaching at the surface from the west. This will lead to the next chance of showers and thunderstorms. The Canadian and GFS models have more amplified solutions for Tuesday and Tuesday night compared to the ECMWF model so ECMWF is farther south with this precipitation while the GFS and Canadian convey more of a direct impact of the precipitation to the region. Temperatures will be generally consistent Friday and Saturday with a range of highs from the upper 70s to mid 80s and then slightly rise Sunday into next week when most readings get into the low to mid 80s. Overall, temperature will not deviate too much from seasonal normals during the long term period. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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High pressure will build east from the Ohio valley overnight and pass south of the area this afternoon. A thermal trough sets up to the north and west of NYC in the afternoon. VFR. Light NW flow overnight gives way to late morning/early afternoon seabreeze development. KLGA will likely develop a NE wind off the East River in the morning which often can persist deep into the afternoon. There is some uncertainty as to how long this direction will persist. Due to the light nature of the winds, there will likely be some variability until the seabreeze works across the terminals. There is low confidence of showers moving in after 06Z Friday at the 30h TAF sites. .OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY... .Thursday night..VFR. .Friday and Friday night...MVFR or IFR conditions possible in showers/tstms. .Saturday...VFR. NW winds G20-25KT. .Sunday and Monday...VFR.
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&& .MARINE... Quiet through Friday. Next chance for SCA conditions may come Friday Night, with enough southerly fetch to allow ocean seas to build to 5 ft, mainly east of Moriches Inlet. Wind gusts on the ocean will be mostly to 20 kt but a few gusts to 25 kt will be possible Friday night. SCA conditions may also be possible Sunday night on the ocean, as westerly flow gusts close 25 kt. && .HYDROLOGY... Some locally heavy rainfall is possible with showers and thunderstorms Friday and Friday night. Otherwise, no significant widespread rainfall is expected through early next week. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...Maloit/JM NEAR TERM...JP/dw SHORT TERM...Maloit LONG TERM...JM AVIATION...DW MARINE...Goodman/Maloit/JM HYDROLOGY...Maloit/JM

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