897 FXUS61 KBTV 151726 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 1226 PM EST Wed Nov 15 2023 .SYNOPSIS... High pressure just to our south and east will bring warmer temperatures and breezy south winds today. Temperatures will continue to warm each day through Friday before a front brings widespread rainfall Friday afternoon into Friday night/Saturday morning. Cooler temperatures will follow the frontal passage along with some scattered post-frontal snow showers lasting through Sunday night. && .NEAR TERM /THROUGH THURSDAY/... As of 1219 PM EST Wednesday...The forecast is largely on track this afternoon with minimal changes. Previous discussion below. High pressure will crest to our south early this morning, then shift south and east later in the day. Developing return southerly flow will set up over our area with increasing south winds in response to tightening pressure gradient. Expect breezy south/southwest surface winds to ramp up shortly after sunrise this morning, peaking this afternoon into this evening with gusts in the 10 to 20 mph range for most areas. Expect locally higher winds over higher summits today with gusts 25 to 40 mph, along with stronger channeled southerly winds up the Champlain Valley with gusts 20 to 30 mph forecast. Strongest winds over the Champlain Valley today will be over Lake Champlain. A Lake Wind Advisory may be needed later in the day, but at this time forecast has winds just below criteria. In terms of cloud cover, stubborn low clouds that have remained steadfast over our area for the past few days are finally eroding early this morning, which is good news for those looking to finally see the sun again. We'll see some high clouds spreading over the area in the wake, but this will allow for at least some filtered sun to reach the surface. The return southerly flow will allow for warmer temperatures today than yesterday, with high temps today forecast in the mid to upper 40s most areas, locally in the low 40s in sheltered areas east of the Greens. A relatively weak front will sink south through our area tonight, but no precipitation is expected. Some brief mid and low level clouds are forecast tonight in the wake of the front, especially over higher terrain in the northern Adirondacks and northern Greens, but no other sensible weather impacts expected. Overnight lows will be around freezing for most of the area tonight. The front will lift northward again through our area Thursday morning as a weak warm front. Ridging will build in the wake of the front, and Thursday looks like a beautiful day overall with sun and highs in the mid 40s to low 50s. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 327 AM EST Wednesday...Warm air advection strengthens overnight Thursday with 925mb temperatures rising to +7 to +12C. Temperatures will likely be non- diurnal west of the Greens. Given that we are now 48 hours out, have started incorporating more local terrain effects for the temperature forecast. The warmest spots would be towards the St Lawrence Valley, which are likely to see overnight temperatures hold steady or even rise a few degrees towards daybreak. On the other hand, the coldest spot overnight Thursday will likely be across the Northeast Kingdom and east of the Greens, where the low- level cold air will be tougher to scour out. It will also become increasingly breezy, with 925mb southwest winds increasing to 25-35 kt, especially west of the Champlain Valley. By late Friday morning, a 40-50 kt 850mb jet overspreads the entire region. Forecast soundings indicate less than ideal mixing, but 25 to 30 mph southwest and southerly winds should still be common. High temperatures should also reach well into the 50s for many locations given the warm start despite abundant cloud cover, with global guidance depicting 850mb and 925mb temperatures in the +7 to +10C and +9 to +12C range respectively. The higher res NAM does indicate the potential for stubborn low-level cold air to hold its ground longer across the Northeast Kingdom, but eventually warmer air should overspread the entire region. Sharp cold front advances from the west with an intensifying coastal low pressure system to our east. At this time, all available global ensemble guidance shows the coastal low tracking south and east of 70W/40N, which means that our region is too far removed from any Nor'easter impacts. So our primary concern will be the cold front that crosses the region late Friday into the overnight hours. The strong pressure rise/fall couplet will induce vigorous uplift out ahead of the front producing an area of precipitation. For our area, this looks to be a mostly if not all rain event Friday afternoon into the overnight hours with the 540 Dm isotherm line lagging well behind the moisture. Also, no concerns with flash freeze with enough time for road surfaces to dry out before temperatures fall below freezing. Total precipitation is forecast to be around 0.25 to 0.75 inches with locally up to an inch, so no hydrologic concerns with the rainfall. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 327 AM EST Wednesday...Heading into Saturday, reinforcing northern stream shortwave energy will likely result in scattered terrain-focused snow showers as snow levels fall to below 1500 ft. The cold air advection will also steepen the low-level lapse rates, allowing for breezy 15-20 mph northwest winds. With temperatures in the 30s to low 40s, it will feel more like the teens and 20s. A wild card to consider is the evolution of the upper level pattern with regards to the coastal low that undergoes explosive cyclogenesis as it tracks close to the 70W/40N benchmark and into downeast Maine/New Brunswick on Saturday. The 00z GFS indicates a faster transition into a negatively tilted trough as downstream ridging builds over Newfoundland by Saturday afternoon. In contrast, the 00z ECMWF is more amplified with the H5 trough, resulting in the transition from neutral to negative tilt not occurring until Saturday night. If the GFS solution materializes, then the colder air will catch up with the exiting precipitation shield, resulting in the formation of an anafrontal wave east of the Champlain Valley and rain changing over to accumulating snow. Whereas if the ECMWF is right, then only scattered snow showers are expected. There is still time for model guidance to come into better consensus so be sure to monitor the latest forecast. Either way, it does look like the most significant wintry impacts with this strong Nor'easter will remain east of our region. Canadian high pressure builds in during the latter half of the weekend into early next week, allowing a continental polar air mass to be entrenched across our region. So expect the coldest air of the season so far to bring below a period of normal temperatures. Typical highs for this time of the year are in the low to mid 40s. At this time, it looks like Monday is the coldest day with 850mb temperatures falling to -8 to -12C per global ensemble guidance. For reference, these values are in the 10th percentile of 850mb temperatures per the SPC sounding climatology for Albany, NY. If the model trends hold, then sub-freezing highs likely outside of the St Lawrence and Champlain valleys on Monday. Temperatures trend warmer and become more seasonable on Tuesday with low to mid 40s returning as a brief H5 ridge builds into the region. While a little outside the forecast period, the weather turns unsettled mid week as we head into the Thanksgiving holiday period. Stay tuned. && .AVIATION /17Z WEDNESDAY THROUGH MONDAY/... Through 18Z Thursday...VFR conditions are anticipated for the next 24 hours. High clouds at or above 20000 ft agl are present across much of the region, with south to southwest surface winds at terminals ranging between 8 and 14 knots, locally faster up to 18 knots and gusting to 28 knots at KBTV and locally slower and southeast at 5 knots or less at KRUT. Beyond 22z, winds will trend towards 5 knots, and may become variable in KEFK, KMPV, and KPBG as a weak front shifts through overnight. A cloud layer between about 5000-7000 ft agl will accompany it, with little or no precipitation expected. LLWS will be possible at KSLK and KMSS between 00z and 06z as the front shifts east with southwest winds at 2000 ft agl increasing to 40 knots, but decays as wind max shifts into Vermont into Vermont. Conditions will remain fairly steady beyond 06z Thursday. Outlook... Thursday Night: VFR. NO SIG WX. Friday: Mainly VFR, with local MVFR possible. Windy with gusts to 30 kt. Chance SHRA. Friday Night: Mainly MVFR, with local IFR possible. Definite SHRA. Saturday: Mainly VFR, with areas MVFR possible. Chance SHRA. Saturday Night: Mainly VFR, with local MVFR possible. Slight chance SHSN. Sunday: Mainly VFR, with areas MVFR possible. Chance SHSN, Chance SHRA. Sunday Night: Mainly VFR, with areas MVFR possible. Chance SHSN. Monday: VFR. NO SIG WX. && .MARINE... A LAKE WIND ADVISORY IS IN EFFECT... South winds will increase to 15-25 knots later this morning into the afternoon. Winds diminish to 5-15 knots this evening. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Duell NEAR TERM...Duell/Haynes SHORT TERM...Chai LONG TERM...Chai AVIATION...Haynes MARINE...