Area Forecast Discussion
Issued by NWS Burlington, VT

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961 FXUS61 KBTV 221410 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 1010 AM EDT Thu Jun 22 2017 .SYNOPSIS... High pressure will build into the region through this afternoon with dry and seasonably pleasant weather expected. Showers and thunderstorms return to the region by overnight Thursday into Friday morning with locally heavy rainfall possible. A brief return to dry weather is expected on Saturday before more showers return for the early portions of next week. && .NEAR TERM /UNTIL 11 PM THIS EVENING/... As of 1008 AM EDT Thursday...Only minor changes to previous forecast for today. Can`t ask for a much nicer day than today, minimal cloud cover, and very low precipitation chances. Feel that best chance for showers remains Adirondacks and westward and generally very late in the period this evening. Otherwise lots of sun, low dewpoints and warm temperatures. Previous discussion...High pressure will continue to build into the North Country today. Mostly clear skies should continue through the morning and we`ve been fortunate that the boundary layer winds have stayed elevated enough to not see much in the way of fog development although its not that far away as the GOES-R Fog product shows fog creeping into the river valleys of central NY and across portions of Quebec. The lone exception to that is Saranac Lake were literally as I typed the previous sentence the visibility started to fall due to ground fog developing. The daylight hours should be quite pleasant across the North Country under mostly clear skies through the morning. Mid to high level clouds will begin to build in from the west as a warm front lifts to the north. The warm air will advecting in but shouldn`t have a significant impact on max temps as 925mb temps will only warm to 17-19C supporting highs in the upper 70s. In the overnight hours, the PWATs surge to 1.7-2.0 inches and moisture convergence increase at the surface leading to rather healthy rain showers developing. The best chance for the showers is generally over norther New York where some areas will see up to an inch of rain overnight. With the warm air advection continuing expect lows to trend warmer in the upper 50s to low 60s under south/southwesterly flow and increasing clouds. && .SHORT TERM /11 PM THIS EVENING THROUGH 6 PM FRIDAY/... As of 430 AM EDT Thursday...Warm air advection well underway by Friday morning with warm frontal rainfall predominantly across northern half of the forecast area. Surface and upper ridge will be to the east, and our area will be opened up to subtropical moisture streaming in from the gulf. Actual remnants of TS Cindy will move east across the mid-Atlantic coast, but we`ll get a good sample of gulf moisture, and 850 and 700 mb theta-e ridge surges into the area by mid day Friday. Model soundings in BUFKIT indicate better warm rain processes in the morning, then some mid level drying in the afternoon. Convective heavy rainfall rates still a threat during the day Friday however driven by precipitable water remaining near 2 inches. Examining severe weather threat...not seeing really strong signals there. NAM model CAPE over 2000 j/kg in the northern Champlain Valley Friday afternoon, however with cloud cover limiting afternoon heating I`m not convinced all that instability will be realized. Additionally shear does not align well with max heating, with one area of higher shear lifting north of the Canadian border Friday morning, then higher shear again along the surface front late in the day Friday after peak heating. SPC has also backed off on risk of severe Friday, with Marginal threat over the forecast area. Based on all this will continue to highlight heavy rainfall threat in the forecast, and downplay strong storm characteristics. Expect area of rainfall to be lifting north during the morning followed by a relative lull, then afternoon convection with heavy rainfall rates firing in max heating and ahead of the approaching front. Scattered showers/thunderstorms to continue into Friday night with passage of the surface front. Boundary to reach St. Lawrence Valley around 06z Saturday, Champlain valley 09z, and across entire forecast area by 12z Sat. Temps Friday in the upper 70s to low 80s. 850 & 925 mb temps support mid 80s, but clouds and rain around should knock a few degrees off the max potential. Most of Friday night will be with high dewpoint air remaining in the area, with muggy mins in the 60s. Cooler and drying trend on Saturday with westerly flow at the low levels backing southwest aloft ahead of the next 500 mb trough settling into the Great Lakes region. Lingering showers in the northern higher terrain supported by differential heating and upslope flow. High temps Saturday in the 70s. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... As of 430 AM EDT Thursday...SHRA/TSRA activity with heavy rainfall risk continues for the early part of Friday night before organized activity moves east early Saturday. Broad upper level trof remains over the Great Lakes and northeast into the middle part of next week. Can`t really find any one period in the extended that will be completely dry with cyclonic flow aloft and weak shortwaves rotating around the base of the trof. SHRA chances will continue in the forecast through the period. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... Through 12Z Friday...VFR conditions expected through this afternoon as skies will be mostly clear under high pressure. Clouds will begin building into the north country this afternoon as a warm front will bring rain showers to the northern taf sites shortly after 00z Friday. Choose to offer VCSH for all sites with prevailing -SHRA between 01-03z for BTV/PBG/MSS/SLK. Winds light WSW turn more SW tomorrow. Outlook... Friday: VFR/MVFR. Breezy. Likely SHRA...Likely TSRA. Friday Night: VFR. Numerous SHRA...Isolated TSRA. Saturday: VFR. Breezy. Isolated SHRA. Saturday Night: VFR. Slight Chance SHRA. Sunday: VFR. Likely SHRA. Sunday Night: VFR. Chance SHRA...Slight Chance TSRA. Monday: VFR. Chance SHRA...Slight Chance TSRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Deal NEAR TERM...Manning/Deal SHORT TERM...Hanson LONG TERM...Hanson AVIATION...Deal

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