Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 170728 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 328 AM EDT Mon Jul 17 2017 .SYNOPSIS... A slow moving upper level disturbance approaching from southern Ontario will bring numerous showers and thunderstorms to the area today, especially this afternoon and evening. A few stronger storms are possible with small hail, gusty winds, and brief heavy rainfall. The upper level disturbance will move east on Tuesday but still a few additional showers or thunderstorms are possible again especially over eastern Vermont. A ridge of high pressure will bring warmer and drier conditions to the area on Wednesday before another frontal system moves in on Thursday and Friday with a chance of showers and thunderstorms. Cooler and drier weather are likely by Saturday under high pressure. && .NEAR TERM /THROUGH TUESDAY/... As of 230 AM EDT Monday...Scattered showers and isolated thunderstorms continue to affect the North Country as an upper level trof approaches from Ontario early this morning. Today continues to look active as the upper level trof moves slowly into the St. Lawrence Valley. East of this feature, ingredients are coming to together for scattered to numerous showers and thunderstorms to develop as the atmosphere becomes sufficiently destabilized by afternoon. CAPE of 1500-2000 J/kg are expected. 0-6km shear is marginal at 20-30 kts with PW`s rising to 1.25" in the mountains to as high as 1.60" in the valleys this afternoon. We should see showers and thunderstorms become fairly numerous/widespread during peak daytime heating hours. A few stronger storm cores are possible with potential for pulse storms with gusty downdraft winds, small hail, and heavy rainfall. Right now it looks like storms should propagate slowly but steadily eastward to preclude widespread flash flooding, but wouldn`t be surprised to have one or two storms produce rainfall of 2 inches or so which is right at flash flood guidance thresholds for 1-3 hr duration. 850 temps should provide high temps in the 80s especially from the Champlain eastward where readings in the valleys should reach the mid 80s. Tonight convective activity will slowly wind down with the loss of insolational heating and should be most active as storms and upper level trof propagate eastward through Vermont. Thus, after midnight expect mainly dry conditions with mild temps in the 60s under partly cloudy skies. Also expecting areas of dense fog after 06z especially in the river valleys after all the expected rain. The upper level trough will continue to move east with rising heights and warm advection Tuesday. It will move out of the the North Country limiting sct showers and thunderstorms to south and east VT through early afternoon. Again high temps in the upper 70s to lower 80s with 850 temps around 13C. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/... As of 310 AM EDT Monday...Relatively quiet period is expected Tuesday night into most of Wednesday as weak high pressure builds in behind departing upper trough. Dry weather is expected Tuesday night through at least midday Wednesday. During the afternoon hours we will see a front start to move down from Canada and there may be some showers or thunderstorms near the Canadian Border late in the day. Above normal temperatures are expected with lows generally in the upper 50s to mid 60s and highs on Wednesday in the 80s. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 310 AM EDT Monday...Pattern becomes a bit more active Wednesday night through Friday as west to northwest flow aloft develops over the area and eventually more well defined front moves down from Canada to further enhance the potential for convection. Best potential for showers and storms will be Thursday into Friday. Deep layer shear increases over the area and instability develops ahead of the well defined cold front moving south out of Canada. Time of day is not conducive as the front does not look like it will move through until the overnight hours Thursday night. Something to definitely keep an eye on. Trend going into the weekend will be for a return to more seasonal temperatures with northwest flow aloft over the area. This pattern will help to keep the weather generally dry over the weekend as well. && .AVIATION /07Z MONDAY THROUGH FRIDAY/... Through 06Z Tuesday...A mix of MVFR/VFR in SHRA isld TSRA northern NY through 12z but expect largely VFR prevail except locally MVFR/IFR vsby heavier SHRA/TSRA+ developing aft 17z, probably reaching BTV 19-21Z as upper level trof moves eastward. Could be some hail, gusty winds, and heavy rain with any TSRA. Winds southerly through 10 kts or less except higher near TSRA. Some areas of IFR Fog developing toward the end of the period after all the rain with partial clearing and light winds. Outlook... Tuesday: VFR. Chance SHRA...Slight Chance TSRA. Tuesday Night: VFR. Slight Chance SHRA. Wednesday: VFR. NO SIG WX. Wednesday Night: VFR. Slight Chance SHRA. Thursday: VFR. Chance SHRA...Chance TSRA. Thursday Night: VFR. Chance SHRA...Chance TSRA. Friday: VFR. Chance SHRA...Slight Chance TSRA. && .MARINE...
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A Lake Thunderstorm Advisory is in effect. A few showers and rumbles of thunder are possible early this morning but stronger thunderstorms will develop by this afternoon. Winds on the lake will generally be light with nearly calm waves but a few of the thunderstorms will be capable of variable and shifting wind directions along with isolated higher gusts and chaotic waves. There is also some chance that a few storms may contain hail, frequent lightning, and torrential rainfall lowering visibilities briefly to under a mile. Thunderstorms should wind down early tonight.
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&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Sisson NEAR TERM...Sisson SHORT TERM...Evenson LONG TERM...Evenson AVIATION...Sisson MARINE...Sisson is the U.S. government's official web portal to all federal, state and local government web resources and services.