Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 201336 AFDOKX Area Forecast Discussion National Weather Service New York NY 936 AM EDT SAT AUG 20 2016 .SYNOPSIS... A weak front will sit across the region today...and gradually weaken into Sunday. Meanwhile, a frontal system will approach from the Ohio Valley on Sunday and move through the region Sunday night. High pressure then dominates next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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A weak shortwave embedded in East coast ridging lingers over the region today. At the surface...a weak backdoor front/trough linger over the region. The shortwave should provide trigger, and weak front...differential heating...sea breeze...and outflow boundaries should provide the focus for isolated to scattered shra/tsra activity today in a marginally unstable airmass. Location of shortwave axis across LI/CT appears to favor locations east of Hudson River for convection. Highs expected to be slightly above seasonable today in the lower to mid 80s, except upper 80s NE Nj and parts of Lower Hud. The threat for rip current development is low through early this afternoon...but may become moderate late today with increasing se wind waves.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... Upper level ridge axis slides east tonight...with embedded shortwave following suit. In it place a vigorous shortwave trough sharpening over the Great Lakes tonight into Sunday...negatively tilts and pivots through the Northeast US Sunday night into Monday. At the surface...the weak backdoor front/trough appears to wash out in the vicinity of the region tonight into Sunday. Would expect diurnal shra/tsra activity to diminish tonight...but cant rule out an isolated shra/tsra overnight. Patchy stratus/fog development expected once again in maritime tropical airmass. Meanwhile...a cold front associated with Canadian low pressure...swings from the Ohio Valley tonight...towards the region Sunday afternoon...and then through Sunday night. Increasingly moist airmass expected on Sunday ahead of approaching trough/cold front. Isolated shra/tsra possible late Sun morning into afternoon if any lead shortwave energy available to provide a trigger in an increasingly moist and marginally unstable airmass. Otherwise...increasing clouds on Sunday...and very warm and humid day. Increasing synoptic lift ahead of the pivoting shortwave/upper jet streak and convergence of tropical moisture ahead of the cold front...should have numerous showers and embedded tstms approaching western portion of the Tri-state late Sunday aft into Sun evening and then translating east across the region Sunday Night. Best forcing appears to be north and west of the Region...with increasing shear in a weak instability environment. Main convective threats appears to be torrential downpours with any convection. The threat for strong to severe storms appears to be quite low at this time due to late day/evening timing and weak instability. If instability can build or line is faster...cant rule out a storm or two with strong wind gusts for areas mainly west of the Hudson late day/early eve. With strengthening low-level veering wind profiles with weak wave development and low lcl`s would have to monitor for rotating updrafts. && .LONG TERM /MONDAY THROUGH FRIDAY/... Cold front pushes well offshore Monday morning. Behind the front expect dry weather conditions as high pressure builds in from the west and dominates through the end of the week. Less humid conditions returns on Monday as dew points drop into the low to mid 50s behind the front. Humidity levels will increase by the middle of the week in response to an onshore flow with dewpoints back into the mid 60s to upper 60s. As for temperatures, expect near or slightly below normal temperatures on Monday and through the middle of the week, then back to above normal thereafter. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
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A weak frontal boundary remains nearby through the day. VFR through the day today. KGON will have MVFR ceilings until around 16z, as stratus slowly lifts. Isolated showers/thunderstorms should develop this afternoon along any boundaries, but coverage will be too isolated to include in the forecast at this time. Amendments are possible. Patchy stratus and fog should redevelop after sunset tonight. Local IFR possible after midnight. Light NE winds become SE after 15z, and speeds increase to around 10 kts. .OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY... .Sunday...Chance of MVFR or less in showers and thunderstorms. SE winds 10-15 KT. Gusts 20-25 KT in the afternoon. .Sunday night...MVFR or less likely in showers and thunderstorms. .Monday...Chance of MVFR or less in shra/tstm early, then VFR with NW Gusts 20-25 KT. .Tuesday-Wednesday...VFR. .Tuesday-Wednesday...VFR.
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&& .MARINE... Light winds are expected this morning before SE winds increase a bit this afternoon. These SE winds persist through the day Sunday, and will increase to 10 to 20 kt Sunday. A cold front moves across the waters Sunday night, and winds shift around to the NW behind the front Monday morning. A few gusts to 20 to 25 kt are possible. High pressure builds Tuesday and Wednesday and winds lighten considerably. Seas look to remain rather tranquil today and tonight. Ocean seas may build slightly to 2 to 4 ft Sunday due to increasing winds. However, elevated seas will subside early to mid week as the high builds. && .HYDROLOGY... Only isolated to scattered showers and thunderstorms expected today. Any thunderstorms that develop will be pulse type and nearly stationary and therefore present a localized minor flooding threat...with a low prob for flash flooding. Sunday afternoon through Sunday night, 1/2 to possibly 1 inch of rain is expected. Minor urban flooding would be the main hydrologic impact from this rainfall...with a localized flash flooding threat from any training cells. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...NV NEAR TERM...BC/NV SHORT TERM...NV LONG TERM...FIG AVIATION...MET MARINE...PW HYDROLOGY...NV is the U.S. government's official web portal to all federal, state and local government web resources and services.