Area Forecast Discussion
Issued by NWS Burlington, VT

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227 FXUS61 KBTV 290918 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 418 AM EST Sun Nov 29 2020 .SYNOPSIS... High pressure nudging northward into the region today will provide the North Country with a dry end to the weekend with increasing sunshine and temperatures slightly above normal. Fair weather will be short-lived though as a strong low pressure system will move into the region Monday and dominate our weather through at least mid- week. The most impactful period of weather will be Monday mid- morning through the evening with rain becoming widespread through the day and a period of gusty east to southeast winds in the mountains late Monday into Monday evening. Cooler and showery conditions are expected late Tuesday through the rest of the work week. && .NEAR TERM /THROUGH MONDAY NIGHT/... As of 417 AM EST Sunday...Pick of the week for weather will certainly be today as high pressure over the central Appalachians nudges northward and finally kicks out the low level moisture that has plagued us the past several days. We should see morning clouds across central/northern portions of the forecast area gradually erode from south to north this morning the sunny skies and slight above seasonal temperatures develop for this afternoon. Look for highs to range through the 40s with the warmest values in the upper 40s across the wider valleys. Dry conditions will persist tonight as well, but we`ll see some increasing mid/high clouds shift in through the night ahead of our next system. Low temps will be quite tricky as winds decouple outside of the wider valleys, and low/mid-level warm air advection increases through the night. Thinking temps will hold in the mid/upper 30s in the Champlain/St. Lawrence Valleys with upper 20s to lower 30s elsewhere. Looking ahead to Monday and Monday night, the forecast remains on track as a northern stream trough will phase with rich southern stream GOMEX energy to develop a dynamic storm system over the south- central Appalachians Monday morning. Consensus storm track of global and mesoscale models brings the surface low northward into central PA early Monday afternoon, and north of Lake Ontario by Monday night. This is perhaps a slight westward nudge from the 12Z NWP, but only slightly and overall does not change the forecast significantly and still places the North Country on the warm and windy side of the storm. Main impacts continue be a swath of moderate rainfall, perhaps starting as a very brief wintry mix in the colder hollows, and gusty east-southeasterly downslope winds. Precipitation will develop early Monday from southwest to northeast becoming widespread by early afternoon along a warm front passage. No concerns with ptype as strong warm advective processes support temps well into the upper 40s to mid 50s. Overall amounts for the 24-hour period will generally range from 0.50-0.75" with localized amounts to 1" in the southeast upslope regions of the Adirondacks and southern Greens. Late Monday into Monday night as a mid-level dry slot works into the region precipitation will become more showery in nature and areal coverage will decrease from west to east. This will be the period where winds could briefly gust up into the 30-45mph range along the western slopes as the core of strong 925-850mb jet passes just east of the region. On the western periphery of the jet core, winds at 925mb peak up to 50-60kts for a very brief period from about 21-01Z, and coincides with the dry slot working in. Details remain very fuzzy whether the low levels will be unstable enough to support mixing these winds to the surface, and while we continue to lean towards more stability, the potential still remains for some brief gusts to 45 mph in the typical southeast downslope locales such as Underhill, Jericho, South Lincoln, Ripton, and especially Mendon and Clarendon. Lows Monday night won`t drop much, holding in the low 40s west to around 50 east, and we could be looking at some record high min temps for Dec 1. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... As of 417 AM EST Sunday...Temperatures are still tricky on Tuesday, as deep mixing will boost temperatures and counteract cooling aloft somewhat. With the very mild/record breaking minimum temperatures, we will be off to a warm start. The warmest air will be towards the northeast, so unusually the warmest conditions may be in the Northeast Kingdom, with highs possibly pushing 60 if the mid-level dry slot works its way towards the low-levels. Much of the period will be dry with some breaks in the clouds possible, with the best forcing for ascent to our west and moisture remaining to our east. However, I have maintained chances for rain showers with questions about how frontogenetic forcing develops over the region which would be the focus for widespread showers. Any rain showers, which have highest chances in northern New York, should change over to snow showers gradually Tuesday night in the Adirondacks and Greens as sub-freezing temperatures aloft drop closer to the ground, minimizing the melting layer. So expect the snow showers to initially fall with surface temperatures well above freezing, and in concert with warm road temperatures, any impacts will likely be due to reduced visibility. Temperatures should be much cooler Tuesday night with temperatures falling back to the upper 20s to mid 30s. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 417 AM EST Sunday...On Wednesday we will see unsettled weather continue as we remain close enough the occluded low pressure area, now near Ottawa, to see plentiful low-level moisture and clouds. Mixed signals for lake- effect snow showers exist over portions of southern St. Lawrence and Essex counties in New York. The instability and moisture will be in place, but wind direction is the question as some data suggests low- level flow will be southerly rather than the necessary southwesterly direction. However, by later in the day, better consensus that winds will go more westerly as the low drifts northeastward. Upper-level shortwave energy will help trigger more snow showers and lake- enhanced snow. These snow showers should diminish by Thursday morning, with best potential for light snow accumulation in the Adirondacks, with the specific area to be fine tuned as we get into the higher resolution model data. Elsewhere, lower chances of precipitation but scattered instability snow showers, or rain in the lower valleys, will develop and move through. With the upper-level low lifting northeastward, the general idea would be best chances of snow showers should be in northern New York during the day and shift into Vermont Wednesday night. Lower chance of precipitation is expected on Thursday, with better chances of some light snow on Friday. Temperatures from Wednesday through Friday should tend to be near normal, or a little above normal at night given propensity for cloud cover. Then a more significant system, which will crash along the Pacific northwest coast tomorrow night, is poised to finally reach our area sometime on Saturday. Unfortunately for snow lovers, all indications at this time are for another rain event, perhaps ending as snow in the mountains. Stay tuned! && .AVIATION /09Z SUNDAY THROUGH THURSDAY/... Through 06Z Monday...Mainly FEW-BKN VFR ceiling are expected through 15Z, trending to SKC thereafter. Only exceptions will be KSLK where MVFR will persist through 15Z, then lift north to KMSS briefly for a few hours this afternoon. Winds will be generally light south to southwesterly from 4-10 kts through the period. Outlook... Monday: Mainly VFR, with local IFR possible. Definite RA. Monday Night: Mainly MVFR, with local IFR possible. Likely SHRA, Definite RA. Tuesday: MVFR. Chance SHRA. Tuesday Night: Mainly VFR, with areas MVFR possible. Chance SHRA, Chance SHSN. Wednesday: Mainly VFR, with local MVFR possible. Chance SHRA. Wednesday Night: Mainly MVFR, with areas VFR possible. NO SIG WX. Thursday: Mainly VFR, with local MVFR possible. NO SIG WX. && .CLIMATE... Below are the record high minimum temperatures for December 1st that have the potential to be broken. KBTV KMPV K1V4 KMSS KPBG KSLK 47|2001 45|2001 45|2001 40|2016 47|2001 46|1914 && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Lahiff NEAR TERM...Lahiff SHORT TERM...Kutikoff LONG TERM...Kutikoff AVIATION...Lahiff CLIMATE...

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