Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 290759 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 359 AM EDT Thu Sep 29 2016 .SYNOPSIS... A closed upper low over the western Great Lakes will move slowly south into the Ohio River Valley overnight, and will linger there through Saturday. Meanwhile, a ridge of high pressure over eastern Quebec and Labrador will slowly build southwest into the region through Friday, with mostly fair and dry weather expected over the North Country. As the closed low moves back north into the Great Lakes this weekend, there will be increasing chances for rain showers from Friday night through this weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 159 AM EDT Thursday...Forecast in good shape at this time, so no changes have been made. Previous discussion from 1015 PM Wednesday...Somewhat of a wide range of temperatures have developed over the area tonight based on clouds versus no clouds. Have fine tuned grids to account for this...but overnight lows are still on track. No other changes needed at this time. Previous Discussion... For tonight, the upper low currently over the southern tip of Lake Michigan only dives slightly south into the Ohio River Valley, while a dirty ridge of high pressure over eastern Quebec and Labrador builds over portions of the northeast. I call it "dirty" because it won`t be your classic high pressure providing clearing skies, rather easterly flow off the Atlantic will persist with variable cloudiness expected through the overnight. This will make for a tricky min temp forecast as areas with more clouds will be warmer than those that are clearer. Have opted for a model blend approach, which will offer min temps generally close to climo ranging through the 40s in general, except a few upper 30s in the colder hollows of the Adirondacks and Northeast Kingdom. Thursday will be almost a repeat of today in regards to temps as southeasterly areas will once again only be in the low/mid 60s and areas northwest pushing into the low 70s. We`ll be under the ridge I mentioned above which will keep us dry, and most areas should see about the same amount of sunshine or more than we saw today. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... As of 345 AM EDT Thursday...The forecast challenge during this period will be northern extent of precip shield...along with impacts clouds will have on temps. Models in good agreement with closed 5h/7h cyclonic circulation over the Ohio Valley with building ridge of high pressure develops over southern Canada. This will continue to produce a east to northeast flow across our region...with mid/upper level moisture trying to advect in from the south. Based on 70% and greater 1000 to 500mb RH fields staying to our south and pw values < 1.0...along with best upper level forcing located to our south...will continue to mention just low chc pops across southern VT zones on Friday. Better moisture tries to make a run into our central cwa on Saturday...but weakens as it encounters dry air associated with ridge of high pres. Thinking a few isolated to scattered light rain showers are possible across our central/southern cwa on Saturday...but qpf will be light and generally under 0.10" Temps will be tricky with highs clouds on Friday...along with some low clouds again across eastern section...and even more clouds areawide on Saturday. Based on yesterday`s cloud impacts on temps...will mention a similar type profile for Friday with highs near 60s eastern near 70 Saint Lawrence Valley and downslope parts of the Champlain Valley. With more clouds anticipated Saturday...thinking highs mainly in the upper 50s mountains to mid 60s warmer valleys...with lows generally in the 40s to lower 50s. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... As of 345 AM EDT Thursday...The deep closed 5h circulation over the Ohio Valley will slowly lift toward the ne conus and weaken by early next week. As cold core aloft and associated energy/moisture move directly overhead by Monday...expect scattered showers. Once chance for precip with the highest pops will be dacks and mountains of vt...with generally light qpf values under 0.25". System will be replaced once again by a large dome of high pres both at the surface and aloft by midweek. Still some uncertainty on timing of high pres and potential lingering moisture/pops on Tuesday...but Wednesday and Thursday look dry. A general warming trend is anticipated...especially daytime highs with more sun anticipated and progged 850mb temps near 8c. This supports highs mid 60s to lower 70s with lows mainly in the mid 30s to upper 40s...depending upon elevation and closeness to Lake Champlain. Overall expect a large diurnal swing in daily temps by midweek due to the expected very dry air mass in place. && .AVIATION /08Z Thursday THROUGH Monday/... Through 06Z Thursday...Mainly VFR conditions expected through the period as a surface ridge of high pressure builds southwest from Quebec into the region through the period. Expecting increasing high and mid level clouds moving into the region today from the mid Atlantic states. These clouds are associated with the closed upper low over the Ohio valley today. Expecting surface winds today to turn into east and northeast today as the ridge of high pressure build southwest from Quebec. Outlook 06z Thursday through Monday... 06z Thu - 12z Sat: VFR under an increasing mid/high deck. 12z Sat - 00z Tue: Mix of VFR/MVFR in scattered rain showers, mainly from 00z Sun onward. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Lahiff NEAR TERM...Evenson/WGH/Lahiff SHORT TERM...Taber LONG TERM...Taber AVIATION...WGH/Lahiff is the U.S. government's official web portal to all federal, state and local government web resources and services.