Area Forecast Discussion
Issued by NWS Burlington, VT

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522 FXUS61 KBTV 172323 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 723 PM EDT Thu Aug 17 2017 .SYNOPSIS... High pressure will shift east tonight as a warm front approaches from the southwest. Showers and thunderstorms are possible with the warm front after midnight tonight into Friday, especially in northern New York. Showers will taper off Friday night, and remain possible on Saturday mainly over the higher terrain. Sunday will be warm, a little less humid, with no rain forecast. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... As of 719 PM EDT Thursday...Current forecast is in good shape. Surface ridge across central New England will continue to shift eastward overnight, allowing a warm front to lift northeast into the region from the eastern Great Lakes. Leading edge of warm and noticeably more moist air to push into mainly the New York side of the forecast area during the overnight hrs. Surface dewpoints in the 50s to be replaced by 60s dewpoints. Precipitable water rises with the surge of warm moist air, 1.5" across most of the region to near 2 inches in the south of the forecast area. Sharp gradient of Showalter Index values moves into northern New York after midnight and this will enhance the potential for elevated convection. The 18Z NAM indicates elevated CAPE approaching 800-1000 j/kg for parcels lifted from 875mb in vicinity of srn St. Lawrence County around 09Z Friday. Thus, some embedded convective elements and thunder possible toward daybreak for the far wrn portion of the CWA, but tstm potl mostly holds off til daylight hrs Friday. Overnight lows will see an early drop, then start to rise around midnight in northern NY and early morning hours in the Champlain Valley. Green Mountains and eastward will experience normal diurnal trend in temps. Lows will mainly be in the mid to upper 50s, except lower 60s expected in the Champlain and St. Lawrence Valleys. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... As of 349 PM EDT Thursday...For Friday the warm front lifts through the rest of the forecast area and showers and increasing chances for thunderstorms as atmosphere destabilizes. Shortwave ridging at 500 mb shifts east, and by mid day Friday upper flow becomes difluent ahead of approaching shortwave trough moving through the Great Lakes Region. Warm moist airmass remains in place through the period with dewpoints remaining well into the 60s. Forecast CAPE 500-1000 j/kg, not great but enough to support some thunder. With high PWATS and warm cloud depth nearing 12,000 feet looking for efficient rainfall production and heavy rainfall rates, however storms should keep moving along to mitigate flooding risk. Highs Friday in the 70s to near 80, and lows Friday night hold in the 60s. && .LONG TERM /SATURDAY THROUGH THURSDAY/... As of 318 PM EDT Thursday...Mainly dry weather is expected from Saturday night through Tuesday morning. Surface ridge builds over the region Sunday keeping things quiet through early Tuesday. A shortwave will cross the area Saturday and Sunday. As the ridge slides to the east Tuesday moisture and warm advection will increase on southwest winds bringing more humid and unstable air to the region, with precipitation chances returning. Deepening low pressure will move from the northern Great Lakes will move up the St. Lawrence seaway by Wednesday bringing unsettled weather once again. Greatest precipitation chances look to be Tuesday night and early Wednesday. Drier weather returns to the region Thursday. && .AVIATION /23Z THURSDAY THROUGH TUESDAY/... Through 12Z Friday...VFR for the first 12 to 18 hours of the TAF period with high pressure in place. Showers along approaching warm front lower cigs and vis to MVFR after 06z northern NY, 12-15 UTC in Champlain Valley and Vermont. Light variable winds today/this evening become southerly with warm frontal passage. Outlook... Friday Night: VFR. Breezy. Slight Chance SHRA. Saturday: VFR. Chance SHRA. Saturday Night: VFR. Slight Chance SHRA. Sunday: VFR. Slight Chance SHRA. Sunday Night: VFR. NO SIG WX. Monday: VFR. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: VFR. Slight Chance SHRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Hanson NEAR TERM...Banacos/Hanson SHORT TERM...Hanson LONG TERM...Manning AVIATION...Hanson is the U.S. government's official web portal to all federal, state and local government web resources and services.