263 FXUS61 KBTV 222343 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 743 PM EDT Thu Jul 22 2021 .SYNOPSIS... Isolated to scattered showers will continue overnight as a shortwave trough passes overhead, though rain will be light. Slightly greater chances for showers and isolated thunderstorms exist for Friday afternoon, but still only isolated to scattered in nature. Saturday will feature sunny skies and warm temperatures, but rain returns Saturday night into Sunday. Drier weather returns to begin next week, with rain chances increasing again by mid- week. && .NEAR TERM /THROUGH FRIDAY NIGHT/... As of 740 PM EDT Thursday...Scattered showers have developed along and north of the international border as a disturbance moves through the flow aloft. These will showers will be capable of producing rumbles of thunder and briefly gusty winds. Although radar presence is rather benign, SPC mesoanalysis indicates 0-3km lapse rates across northern New York and Vermont are between 7.5-8 degrees C respectively. These steep low level lapse rates are supportive of gusts in the 20-30kt range, with recent upstream obs from Ottawa reporting a gust up to 33 kt. Even as daytime heating wanes, cold pool aloft should support elevated instability overnight. Therefore have continued mention for slight chance of thunder through the overnight hours across the area. No other changes were needed to the forecast. Previous Discussion...The North Country remains under broad troughiness and northwest flow, allowing few isolated showers to pop up across portions of Vermont this afternoon. Chances for isolated to scattered showers will increase overnight as an embedded shortwave and associated surface boundary traverse the area, with the best chances across northern New York. Meanwhile, lesser chances exist across the Northeast Kingdom of Vermont resulting in slightly cooler overnight temperatures and the potential for fog development. In general, overnight low temperatures will be in the 50s with upper 40s across the Northeast Kingdom. Friday will be similar to today under filtered sun and light northwest winds. High temperatures will again be the 70s. There remains a chance of scattered showers with isolated thunderstorms during the afternoon as temperatures cool aloft, resulting in steepening lapse rate and marginal instability. By Friday night, shower/thunderstorm activity will wane as the upper trough pushes eastward and high pressure begins to build in from the west. This will result in clearing skies and light winds overnight; paired with a cooler airmass overhead, we will see low temperatures in the upper 40s to mid 50s. Low temperatures in the mid 40s are possible within cold hollows. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... As of 341 PM EDT Thursday...Saturday will be a pleasant day as we see some brief ridging. While we will start out with ample sunshine, clouds start increasing from west to east late in the day as the ridge axis shifts east and our next system approaches from the Great Lakes. Highs will be in the mid 70s to lower 80s. More active weather is expected for the latter half of the weekend as a series of frontal boundaries/surface troughs migrate through the region. A warm front will lift into the area Saturday night. Behind this boundary, moisture will spread northward on a 30-40kt low-level jet, and PWATs will quickly rise into 1.5-2 inch range. Showers spread eastward into the North County Saturday evening and continue into Sunday morning. We look to remain fairly stable overnight, with perhaps just some elevated instability working into the St Lawrence Valley toward daybreak Sunday, so don't anticipate much more than perhaps an embedded thunderstorm or two. Regardless, given the deep moisture, briefly heavy rain will be possible overnight. The night will likely be on the muggy side with lows in the upper 50s to mid 60s. A surface trough will cross the area Sunday, helping to usher the deeper moisture eastward. Depending on how quickly clouds from overnight/early morning precipitation move through, instability will increase through the day as we see steepening low-level lapse rates from diurnal heating. But with decreasing moisture, anticipate any showers/thunderstorms would be scattered in nature. Still, with SB CAPE progged to reach around 900 J/kg and 0-6km shear 40-45 kt, any convection that does develop may need to be watched. Sunday's highs will be similar to Saturday, except for eastern VT where clouds will linger longest, keeping temperatures in the lower to mid 70s. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 341 PM EDT Thursday...We remain under an active pattern for much of next week as several shortwaves will scoot along through the fast west-northwest flow aloft. These are usually quite hard to pinpoint in time and strength, so can't really completely rule out at least a minimal chance of showers each day. Temperatures will remain seasonal, warmest Monday and Tuesday when highs will be in the upper 70s to lower 80s, then slightly cooler as we head through the middle part of the week. && .AVIATION /23Z THURSDAY THROUGH TUESDAY/... Through 00Z Saturday...VFR conditions are expected across the airspace through the TAF period. Isolated rain/thunder showers will move through the North Country. At this time have mentioned VCSH at all terminals, however cannot rule out VCTS at KPBG & KBTV over the next couple hours. In addition, briefly gusty winds 20-30kt along with reduced visibilities are possible in the stronger of showers. After 06z, activity should largely wane with light and variable winds expected overnight. Showers/thunderstorms will redevelop tomorrow afternoon therefore have included VCSH at all terminals after 16z. Winds should generally be light and variable during the afternoon hours, however any showers/thunderstorms that do develop may produce briefly gusty winds. Outlook... Friday Night: VFR. NO SIG WX. Saturday: VFR. NO SIG WX. Saturday Night: Mainly VFR, with areas MVFR possible. Likely SHRA. Sunday: Mainly MVFR, with local IFR possible. Chance SHRA, Chance TSRA. Sunday Night: VFR. Chance SHRA. Monday: VFR. Slight chance SHRA. Monday Night: VFR. Slight chance SHRA. Tuesday: Mainly VFR, with local IFR possible. Chance SHRA, Slight chance TSRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Lahiff NEAR TERM...Hammond/LaRocca SHORT TERM...Hastings LONG TERM...Hastings AVIATION...LaRocca