258 FXUS61 KBTV 081907 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 307 PM EDT Fri Oct 8 2021 .SYNOPSIS... Building high pressure over northern Maine will help to push a backdoor cold front across the region tonight into Saturday. This boundary will have limited fan fair, but temperatures will be cooler and more clouds are likely on Saturday. A weakening system will produce additional clouds with maybe a few sprinkles late Saturday night into Sunday. && .NEAR TERM /THROUGH SATURDAY NIGHT/... As of 306 PM EDT Friday...Crnt sfc analysis places weak backdoor cold frnt approaching the NEK of VT, while building 1028mb high pres is located over northern Maine. This boundary and associated high pres wl increase bl to 925mb se winds overnight at 15 to 25 knots, resulting in much less fog/br development. In addition, developing se upslope flow over central/eastern VT, wl help advect in better moisture along the spine of the Green Mtns with some areas of stratus possible overnight into Sat. Difficult to determine areal coverage of stratus, as models prog rh fields develop overnight and coverage upstream based on vis sat imagery is minimal. Some very patchy fog is possible acrs the dacks as winds decouple and skies remain clear. As high pres builds toward the NEK by 12z Sat, NAM 3km showing drying bl dwpts, which wl allow temps to drop into the u30s/l40s with mid 40s SLK to l/m 50s SLV/CPV. Saturday 1030mb high pres remains over northern Maine, while s/w energy and moisture lifts toward the Ohio Valley/central Great Lakes. The gradient btwn these two systems wl increase, resulting in south/southeast winds 5 to 15 knots on Saturday. In addition, llvl thermal gradient tightens with progged 925mb temps near 12C SLV to 7C NEK, supporting highs lower 70s SLV to lower 60s NEK/Eastern VT. Have noted the NAM12 and NAM 3KM both increasing moisture along the spine of the Green Mountains on Sat, associated with se upslope flow. Wl increase clouds for this area and keep temps slightly cooler. On Saturday night, s/w energy and mid level moisture in the southwest flow aloft approaches our western cwa aft 06z. Have continued to mention chc pops btwn 06-12z Sunday to cover this potential. Energy and moisture looks to weaken as it encounters strong high pres to the east, with just a few sprinkles possible over the CPV and parts of VT. Temps wl remain on the mild side with lows mid 40s to mid 50s most locations. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... As of 400 AM EDT Friday...A shortwave trough will traverse the North Country during this period, causing an increase in cloud cover but low chances of precipitation. A fairly deep layer above the surface will remain dry under the influence of ridging with the strong surface high still parked near Nova Scotia. Forecast soundings as a result suggest a thick high cloud layer with dry air below in many areas. However, northern New York, mainly north and west of the Adirondacks, should see a period of low clouds with a few showers possible Sunday morning in response to the trough where the ridge to the east has less influence. These clouds along with increasing southwesterly flow aloft will keep low temperatures relatively mild in the 50s, with other locations across the North Country tending to be closer to seasonable norms dropping down into the 40s. As with Saturday, we will continue to see an easterly component to the wind over much of Vermont. Therefore, a repeat of low clouds in portions of eastern Vermont is possible, although it looks like trajectories start to become more southwesterly moving through the day. A mostly cloudy sky is offered for much of the period but would not be surprised if there are adjustments needed. Again, precipitation chances remain low (20% or less) through Sunday. Temperatures should remain above normal by about 3 to 6 degrees with 60s in most locations for highs. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 400 AM EDT Friday...Outside of a weak low pressure system moving over the North Country on Wednesday, the long term will be consistently quite warm and dry with a deep longwave trough out in the western US supporting downstream ridging over our area through the rest of the week. Noted that GFS 2-meter temperature anomalies exceed 20 degrees on Tuesday in northern portions of the region, with even the ensemble mean only a few degrees lower, suggesting potential for upper 70s to low 80s high temperatures. For now, continue to go higher than the NBM on Monday and Tuesday with temperatures remaining a 5 or so degrees lower than potential values. Tuesday is particular promising for warmth as the 850 millibar thermal ridge centers over our area during the afternoon and some drier air at the top of the mixed layer could help further boost temperatures. Wednesday shower chances are higher as one goes west and still are low (30% or less). Some of the latest model data supports trending chances upward across northern areas given the track of the best dynamical forcing, but the system will not pack much punch with rainfall. The main impact will be briefly cooler conditions. Then quiet and warm conditions return for Thursday, although the air mass will likely be less warm than on Monday and Tuesday. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... Through 18Z Saturday...VFR conditions with light winds are expected for the next 6 hours at all taf sites. A backdoor cold front approaching the region from eastern VT this evening will increase the gradient across our taf sites. This will result in stronger bl winds of 5 to 10 knots with higher values in the 400 to 600 feet above ground level to limit fog development overnight. In addition, increasing moisture on southeast upslope flow will result in some mvfr cigs toward midnight at MPV and possibly EFK. Soundings at SLK indicate lighter bl winds and potential for some mvfr/ifr vis in fog/br, so have tempo this into the taf btwn 07-11z. Otherwise, light and variable winds become southeast 5 to 10 knots overnight, except northeast at KMSS, before shifting to the southeast on Saturday. Outlook... Saturday Night: VFR. NO SIG WX. Sunday: Mainly VFR, with local MVFR possible. NO SIG WX. Sunday Night: Mainly VFR, with local MVFR possible. NO SIG WX. Columbus Day: Mainly VFR, with local MVFR possible. NO SIG WX. Monday Night: Mainly VFR, with local IFR possible. NO SIG WX. Tuesday: Mainly VFR, with local IFR possible. NO SIG WX. Tuesday Night: VFR/MVFR conditions possible. Slight chance SHRA. Wednesday: Mainly MVFR, with local IFR possible. Slight chance SHRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Taber NEAR TERM...Taber SHORT TERM...Kutikoff LONG TERM...Kutikoff AVIATION...Taber