Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 230631 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 231 AM EDT Sat Jul 23 2016 .SYNOPSIS...More scattered showers and thunderstorms move across the North Country today as an upper level disturbance moves through. Some thunderstorms may have gusty winds and small hail. Sunday looks mostly sunny and seasonable under hand yet another possibility of showers and thunderstorms late Monday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... As of 230 AM EDT Saturday...Little change in this update. Showers and thunderstorms have moved out of the region. Some hint of additional showers in the models through 12z but am not seeing any evidence of that on radar or satellite. Enough breaks across area that some patchy fog around especially where it rains this evening. lows mainly in the 60s. Today: A potent shortwave expected to move across our area in the afternoon with cooling aloft down to -15C at 500mb. The dynamics are expected to kick off thunderstorms (actually, there will likely be a cluster of thunderstorms as well with that shortwave that will move southeast out of Quebec and into our region). Each model has a differing evolution of the convection, and is again a symptom of just how sensitive the models are to this type of weather pattern that is driven by mixed layers, elevated and low level instability and boundary layer details. Taking a blend of the models suggests that we`ll have CAPE values 750 to 1500 J/kg, highest in the St. Lawrence Valley which is decent enough to drive convection. Models have 30-40kt 0-6km shear mainly south and west portions of our area while shear over VT is 15 to 25 kts. So we can`t totally rule out a stronger storm with gusty winds and small hail, so have included in the forecast. Looks like the highest chances for storms will be from mid-day until early evening. SPC has this same region marked with "Marginal Risk" and at this point, that seems like a good assessment. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... As of 310 PM EDT Friday...Scattered showers/storms (a few possibly strong early) then wane and exit east fairly quickly Saturday evening as upper trough swings through the region and is replaced by building high pressure. Will carry 30/40 pops through about 900 pm or so to account for timing uncertainties, then trend conditions largely dry from midnight onward. Low temperatures near seasonal mid-summer norms in the 50s to around 60 for most locales. Ideal weather then expected by this coming Sunday with surface high pressure bridged by dry and zonal westerly flow aloft. Mean 925-850 mb thermal profiles support highs in the 77 to 83 degree range under light west to northwesterly winds and ample sun. This definitely will be the better day of the two weekend days. By Sunday night our next shortwave trough in the pipeline begins to approach from the Great Lakes with mid to high level cloudiness advecting into the region later at night as flow backs to southwesterly and warm thermal advective processes begin aloft. There could be a stray shower or isolated storm in developing mid- level instability as lapse rates aloft steepen and heights begin to fall, but drier air in lower levels should preclude anything widespread. Will carry a nominal 20/30 pop across our western counties to account for any activity that may occur. Low temperatures a blend of available guidance supporting values generally in the 55 to 65 degree range. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 310 PM EDT Friday...The shortwave trough then swings quickly through the area Monday into Monday evening with a good threat of showers and storms. Some parameters support a few stronger storms but early indications suggest plenty of mid/high level moisture around that could limit boundary layer destabilization ahead of the associated surface trough. Time will tell how this all pans out. For now have maintained continuity offering solid pops in the 40-60 percent range. Temperatures should average slightly above seasonal levels with highs in the 80s and lows Monday night in the 60s. Behind this system our typical mid-summer pattern continues with the region largely on the south edge of the westerlies and deeper heat and humidity off to our south and west. Temperatures should average slightly above seasonal levels with daily highs generally in the 80s and overnight lows in the 55 to 65 degree range. Additional shortwave energy riding through the mean flow may affect the area by next Thursday or so, but timing and strength differences in this morning`s global models support capping pops below 40 percent at this point. && .AVIATION /06Z Saturday THROUGH Wednesday/... Through 06z Sunday...Mainly VFR except some patchy fog until 12z for KSLK and KMPV. Aft 15z Sat...VFR, with scattered brief MVFR/IFR in showers and thunderstorms. Some thunderstorms may contain strong winds and hail. Showers and storms diminish between 00-03Z. Winds generally light west to northwest at 5 to 10 knots. Outlook 06z Sunday through Tuesday... Sat Ngt...VFR but some localized MVFR/IFR due to patchy fog. Sun...Mainly VFR under weak high pressure. Mon/Monday night...VFR with scattered brief MVFR/IFR in showers and thunderstorms with frontal passage. Tuesday...VFR/high pressure. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Sisson NEAR TERM...Sisson SHORT TERM...JMG LONG TERM...JMG AVIATION...Sisson/SLW is the U.S. government's official web portal to all federal, state and local government web resources and services.