Area Forecast Discussion
Issued by NWS Burlington, VT

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590 FXUS61 KBTV 170002 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 802 PM EDT Wed Aug 16 2017 .SYNOPSIS... Dry weather is expected across the North Country through Thursday night as high pressure builds over the northeast. Temperatures will quickly return to seasonal normals Thursday and Friday. A low pressure system approaching the area on Friday will bring a return of showers and a few thunderstorms beginning Friday afternoon. && .NEAR TERM /UNTIL 7 AM THURSDAY MORNING/... As of 800 PM EDT Wednesday...Tranquil night expected across the North Country. High pressure, lower dewpoints, and subsidence will lead to star filled skies. This will lead to relatively cool conditions, especially in sheltered valley locations with light winds and excellent radiational cooling. Fog may form in the most favored valley locations overnight but this will quickly dissipate early Thursday morning. Overnight lows will be cool for this time of year with lows in the lower 50s in the Champlain Valley with some locations in the Adirondacks and Northeast Kingdom reaching down to near 40. && .SHORT TERM /7 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... As of 132 PM EDT Wednesday...High pressure remains over the area on Thursday leaving a stellar day across the board with temperatures returning to near normal with light winds. Clouds advancing ahead of the next system moving into the Great Lakes should hold off until Thursday night. Model consensus continues to show precipitation holding off until Friday, and most likely friday afternoon and evening. Have continued the trend of keeping POPs restrained early Friday and ramping up through the day with highest pops Friday evening. Model forecast soundings show at least some modest elevated instability so have some thunder chances included as well. The system will be fairly progressive so lingering heavy rainfall potential appears to be low despite PWATs increasing to between 1.5 and 2" as indicated by the GFS. Overall a solid moderate rainfall event for much of the region. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 340 PM EDT Wednesday...Overall not too much different from the previous forecast based upon the 12z guidance suite -- perhaps the exception being a little later timing for the system mid-week. Still looks like warmer than normal temperatures through the period, especially as we get into Monday and Tuesday. Didn`t stray far from the blend of guidance as the 12z GFS and ECMWF weren`t too different than each other and the previous 00z run. If you are curious for some additional details in the forecast, just keep on reading... Saturday: still have upper trough approaching the region during the day, and along with a good amount of residual moisture, we should see a few showers develop throughout the day. Instability looks limited, especially across northern NY. GFS and NAM indicate some CAPE across Vermont and point east, so have painted in a slight chance of a thunderstorm for the afternoon hours for the eastern half of the region. Not looking for anything strong or any kind of heavy rain issues. Won`t be a washout at all, but just one of those days where we can`t rule out showers. Sunday: Upper trough will be passing overhead during the day, but not too much in the way of low level moisture or other forcing. With the trough also comes some "cooler" air aloft (about 11C at 850mb) and that will limit the overall instability potential for the day. Thus looking for a good deal of sunshine with highs pretty close to normal for this time of the year. Definitely the better of the two weekend days. Monday (Eclipse Day): Looks like Mother Nature will cooperate for us, and allow us a good view (make sure you are wearing proper eye protection!) of the partial eclipse in these parts. High pressure at the surface, along with weak ridging aloft should keep things dry for the vast majority of the area. 850mb temperatures warm to about 15C, so we`ll see high temperatures reaching the mid 80s for the lower elevations, and close to 80 in the higher terrain. Tuesday: Ridging moves off to our east, allowing a southwest flow to develop at the surface through mid-levels. A shortwave will also be moving into the Great Lakes region by late in the day. Previous model runs were a little faster with this shortwave, and with the slower solutions, have backed off on the chance for precipitation. Still, with height falls, an EML layer, some shear aloft and decent surface instability/CAPE thanks to temperatures well into the 80s, there are suggestions we`ll have some convection around by the afternoon. Have painted in roughly 30-40% chances. By the way, Tuesday should be the hottest day of the stretch. GFS suggests 850mb temperatures up to 17C or so, which support highs in the mid-upper 80s in the valleys, if not making a run at 90F in a few places. This will be dependent on cloud cover however, and if that upper trough speeds up, there would be more showers and clouds around which would keep us a bit cooler. Tuesday Night/Wednesday: Confidence in the details are admittedly not too high. Differences between 12z GFS and ECWMF models are more significant with the timing of the shortwave passage and it`s associated convection. Euro is quickest, with everything pushing off to our east by Wednesday morning, while the GFS has the trough coming through during the day Wednesday. As mentioned earlier, this is also slower than prior model runs. Given those differences, the forecast for Tuesday night and Wednesday are more general in nature and subject to considerable change before we get there. So have 45-60% PoPs for the entire period based upon the model blends. Based on this timing, the threat for strong/severe t-storms is lower, however if future model runs change their timing such that the trough swings through during the daytime heating, then the potential for stronger storms increases. At this point, it`s more of a "wait and see" situation. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... Through 00Z Friday...Drier air has filtered into the North Country on northerly flow with dewpoints falling into the 40s as of 23ZWed. As surface high pressure crests over the region, light to calm winds and clear skies will persist overnight. VFR conditions expected for all terminals the first half of the night. MVFR to IFR conditions possible at KSLK and KMPV but may be more intermittent as some mesoscale models show 20kt jet around 2-3kft AGL. Elsewhere, temperatures do not look to fall below crossover temperatures and will remain VFR. Mid Thursday morning, expect VFR conditions at all sites to persist throughout the day. Winds pick up generally out of the NW during the midday at 5-10kts. Outlook... Thursday Night: VFR. Slight Chance SHRA. Friday: VFR. Likely SHRA...Slight Chance TSRA. Friday Night: VFR. Likely SHRA...Slight Chance TSRA. Saturday: VFR. Chance SHRA...Slight Chance TSRA. Saturday Night: VFR. Slight Chance SHRA. Sunday: VFR. Slight Chance SHRA. Sunday Night: VFR. NO SIG WX. Monday: VFR. NO SIG WX. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Manning NEAR TERM...Banacos/Manning SHORT TERM...Manning LONG TERM...LaRocca/Nash AVIATION...KGM is the U.S. government's official web portal to all federal, state and local government web resources and services.