105 FXUS61 KBTV 141350 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 950 AM EDT Wed Jul 14 2021 .SYNOPSIS... A slow-moving upper trough across the central Great Lakes region will bring another round of showers and thunderstorms to much of the North Country today. A few stronger thunderstorms will produce heavy rain and gusty winds in localized areas. Increasing sunshine will allow for very warm conditions Thursday and Friday, with some valley high temperatures approaching 90 degrees. Another frontal system approaching from the west will interact with the hot and humid air mass to bring another round of showers and thunderstorms late Friday into Friday night. && .NEAR TERM /THROUGH THURSDAY/... As of 949 AM EDT Wednesday...Forecast is on track for the rest of today and looks real good. Water vapor shows the surface and upper trof moving into the region right now accompanied by showers and isolated thunderstorms. This will be moving across NY this morning, into the Champlain Valley early this afternoon and then out of the area this evening. The bulk of convection is still anticipated to increase late this morning and continue through the afternoon. Until then, plentiful cloud cover will persist, with a few breaks seen upstream. A question remains for eastern VT and whether the residual cool maritime airmass will be displaced or heated out this afternoon. With the clouds looks like a tall order so temperatures will be cooler east in the 70s, while west of the Greens should see some lower 80s this afternoon. Previous discussion...Main concern for today is the potential for showers/thunderstorms this afternoon. The rain currently crossing the region early this morning will exit by daybreak or so; the question thereafter becomes how much clearing we can get ahead of a surface trough which will push through the area later this morning into the afternoon. Current guidance indicates SB CAPE of up to 1500 J/kg will be possible, especially across much of Vermont, along with 0-6km shear around 30 kt. However, mid-level lapse rates are unimpressive, and coverage/intensity of any convection is in question. Still, locally gusty winds will be possible in any stronger storms. PWATs remain near or above 1.50 inches, keeping the threat of briefly heavy rainfall with any thunderstorms. We remain under a Marginal Risk in SPC's latest Day 1 severe weather outlook, and this seems reasonable. Latest CAM consensus shows showers redeveloping over the Adirondacks late this morning ahead of the surface trough, then convection becomes more robust over Vermont mid/late this afternoon before winding down and moving into New Hampshire by sunset or shortly thereafter. Highs today will mainly be in the mid 70s to around 80, perhaps a bit warmer in those locations that can see some sunshine. Precipitation will come to an end by midnight tonight with skies becoming mostly clear to partly cloudy. Patchy fog will be possible in favored sheltered valleys, especially those that see rain today and can get clearing overnight. Lows will be in the lower to mid 60s areawide. Warm and dry conditions are then expected Thursday as we see brief ridging along with a mix of sun and clouds. Highs will range from the lower/mid 80s in the mountains to mid/upper 80s in the wider valleys, with a few locations approaching 90. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/... As of 355 AM EDT Wednesday...It should be a fairly warm and humid Thursday night with chances of showers increasing over the St. Lawrence Valley closer to an approaching frontal boundary. Ahead of this cold front, gradient flow will initially be light but tighten a bit towards daybreak, so the temperature curve may support temperatures falling a bit after dark and then leveling off in the upper 60s to low 70s in most locations. Because the surface boundary is weak, the pieces of how the puzzle fits together on Friday for showers and thunderstorms is still unclear with various model guidance handling upper-level forcing in different fashion. These differences will determine the combination of shear and instability that will be in place ahead of the front, so for now can only advertise potential for strong thunderstorms where surface heating is best, which will likely be over central and southern portions of Vermont and Adirondacks. Have temperatures near the National Blend of Models, which shows a decent gradient from northwest to southeast. This pattern matches the idea of clouds and early showers and thunderstorms over northwestern areas limiting heating in an otherwise very warm air mass that will allow temperatures to soar back into the mid and upper 80s in much of central and southern Vermont such as within the southern Champlain, Winooski, and Connecticut River Valleys. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 355 AM EDT Wednesday...Potential for hazardous conditions due to heavy rainfall continues, mainly early in the long term period. Subtle waves aloft will ride along a lingering and light southwest flow to spark periods of rain, and low chance of thunder, on the north side of a wavering front Friday night through Saturday. The latest data continues to trend precipitation chances downward as we move forward in time, with less cloud cover and more scattered shower activity as we move into Sunday and Monday. Greater surface high pressure will help overwhelm continued shots of energy aloft, yielding more of a typical summer day with partly sunny skies, afternoon scattered showers and thunderstorms, and moderate temperature and humidity levels. As we approach midweek, a large ridge building out over the intermountain west will force weather systems southeastward over central Canada early in the week, which will help send a strong cold front towards the North Country. A dry and refreshing air mass with dew points dropping well below 60 is currently expected to arrive Wednesday, but would not be surprised if it arrived as soon as Tuesday. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... Through 12Z Thursday...VFR/MVFR conditions, mainly due to low ceilings, will persist through much of the daylight hours today, with local IFR at KMPV through 14z. Scattered showers/thunderstorms develop after 16z, especially from the Champlain Valley eastward. These will dissipate 00z- 03z, with local IFR possible in any thunderstorms. Clearing conditions from west to east after 00z Thursday. Winds will remain out of the south around 10 kt with local gusts to 20 kt through 00z Thursday, becoming light thereafter. Outlook... Thursday: VFR. NO SIG WX. Thursday Night: VFR. Chance SHRA. Friday: Mainly VFR, with local MVFR possible. Chance SHRA, Slight chance TSRA. Friday Night: Mainly VFR, with local MVFR possible. Chance SHRA, Slight chance TSRA. Saturday: Mainly VFR, with local MVFR possible. Chance SHRA. Saturday Night: Mainly VFR, with local MVFR possible. Chance SHRA. Sunday: Mainly VFR, with local MVFR possible. Chance SHRA. && .MARINE... As of 948 AM...A Lake Wind Advisory remains in effect. South winds of 15 to 25 kt will continue through the early morning hours today before subsiding to 10 to 15 kt later today. Winds starting to come down as of mid morning, but with gusts still over 20 so will hold onto the advisory until this afternoon. Waves will be 2 to 4 feet over northern portions of Lake Champlain, with 1 to 3 foot waves expected south. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Hastings/Sisson NEAR TERM...Hastings/Sisson SHORT TERM...Kutikoff LONG TERM...Kutikoff AVIATION...Hastings MARINE...Hastings