208 FXUS61 KBTV 261125 AFDBTV AREA FORECAST DISCUSSION National Weather Service Burlington VT 725 AM EDT Wed Jun 26 2019 .SYNOPSIS... Warm and moderately humid summertime weather return today through through Friday. Scattered showers and thunderstorms are expected across portions of the area later today with mainly dry weather Thursday and Friday outside a stray shower or storm. A better chance of showers occurs by the upcoming weekend as a cold front pushes through the area. && .NEAR TERM /THROUGH THURSDAY/... As of 620 AM EDT Wednesday...Only adjustment at 600 am was to introduce more clouds and a low-end chance of a shower or stray storm across the SLV through mid-morning to account for current activity tracking east-northeast on the north side of Lake Ontario. Models struggling a bit with this activity, but showing it weakening as it progresses eastward through 900 am. Rest of forecast and overall thinking remain unchanged. Have a great day. Prior discussion... The forecast remains on track for today with warm and moderately humid weather expected. There will be some lingering patchy low stratus east of the Greens through about mid-morning but this will quickly burn off under strong early summertime insolation. Model- blended 925 hPa thermal profiles from 18-21 UTC average from 19-20C, supporting highs in the upper 70s to mid 80s in most spots. Boundary layer instability climbs into the 1200-1800 J/Kg range by late afternoon/early evening, especially from the Champlain Valley west, though lack of deep layer forcing and ambient dry air in the mid- levels should limit overall convective activity in most areas. As a result, storms that do form will have to rely on mesoscale forcing and today this will come in the form of the Lake Champlain lake breeze across eastern NY and in advance of a weak surface trough approaching the SLV. Timing would be generally in the 3-9 pm time frame. Highest coverage appears to occur across the northern Champlain Valley from 4-6 pm before activity expands and weakens heading east into portions of north central/northeastern VT by early evening. While most of the activity should be garden variety, localized strong cores could produce brief gusty winds and hail given the dry air aloft and through the -10C level. Highest threat area appears to lie in the Champlain Valley but again this would be isolated and concur with SPC SWODY1 marginal risk. Any lingering showers/storms then end this evening leaving largely dry conditions overnight. Some scattered/patchy fog possible here and there, especially in areas that receive rainfall but this will be the exception rather than the rule. Lows to range from 55 to 65 in general. Warm weather then continues for most of the area on Thursday with high temperatures from the upper 70s to mid 80s under weak high pressure. There could be a few showers/storms drifting south into northern counties toward late afternoon or early evening as a weak shortwave trough passes well north of the region but for most spots dry weather will be the rule. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 336 AM EDT Wednesday...The forecast area will remain vulnerable to shortwave energy moving through the largely zonal flow as ridging persists to our south and a large upper-level low rotates to our north over James Bay. One such wave will bring some weak showers to northern portions of the forecast area early Thursday night, but expecting the area to be dry by daybreak Friday morning. After a dry start to the day, precipitation chances will increase through the day Friday as models continue to indicate the remnants of a Midwestern MCS moving eastward towards New England. Still some question as to the track and timing of the system, but it's looking increasingly likely that the MCS will track through southern NY and into southern New England Friday night, keeping the brunt of the precipitation to our south. As such, have kept PoPs higher over southern portions of the forecast area than areas further north. There is some marginal elevated instability as the system rolls through overnight, so some rumbles of thunder can't be ruled out...but with MUCAPE values generally under 300 J/kg not expecting anything more than that. Temperatures Thursday night through Friday night will continue to be above normal with conditions feeling increasingly muggy as the week comes to a close. Lows Thursday night will be in the upper 50s to mid 60s. Highs Friday will be in the low to mid 80s. Friday night in particular will feel the muggiest as dewpoints climb in to the low 60s and temperatures only fall to the low to mid 60s. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 336 AM EDT Wednesday...A pattern change is in store for the weekend with a return to cooler conditions expected. This will be due to the southward movement of a sprawling upper-low that has remained over James Bay over the past few days. Height falls over the North Country on Saturday ahead of the low, combined with diurnal instability and favorable upper-level jet dynamics, will allow showers to once again blossom over the area Saturday afternoon. As the cold-core low drops into northern New England Saturday night into Sunday, showery conditions will continue through the majority of the weekend. The upper-low will push a cold front through the area Saturday night into Sunday morning, which will allow temperatures to drop back below normal by Sunday. The upper low will exit the region Sunday night, and ridging will build in to start the next work week. Consequently, temperatures will trend warmer and conditions drier. By Tuesday afternoon however, ridging will move out of the area and the chance for showers returns. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... Through 012Z Thursday...Mainly VFR through the period under light southerly flow generally less than 10 kts. A brief, passing shower is possible at KMSS from 14-15Z, otherwise the area stays pcpn-free until 19Z. After 19Z scattered showers and a few storms will be possible. Blend of available guidance suggest highest probabilities at KBTV, KPBG and KMPV during the 20-01Z time frame though actual time of being affected will likely last an hour or less. At this point given the expected scattered nature of convection only VCSH will be offered. While VFR will remain the prevailing conditions during this period, brief MVFR and/or IFR along with gusty winds will be possible with any storm. After 00-01Z, showers taper off leaving mainly VFR overnight. Some hints of IFR/fog returning to a few terminals after 06Z. Low confidence at most spots for now and have only included at KMPV where probabilities are highest. Outlook... Thursday: VFR. Slight chance SHRA, Slight chance TSRA. Thursday Night: VFR. Slight chance SHRA, Slight chance TSRA. Friday: VFR. Slight chance SHRA. Friday Night: VFR. Chance SHRA. Saturday: Mainly VFR, with local MVFR possible. Chance SHRA, Slight chance TSRA. Saturday Night: VFR. Chance SHRA. Sunday: Mainly VFR, with areas MVFR possible. Likely SHRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...JMG NEAR TERM...JMG SHORT TERM...RSD LONG TERM...RSD AVIATION...JMG