Area Forecast Discussion
Issued by NWS Burlington, VT

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KBTV 201817 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 117 PM EST Mon Nov 20 2017 .SYNOPSIS...
-- Changed Discussion --
Snow showers will diminish by early evening. Milder but breezy weather is expected for Tuesday. A cold front will come through the region late Tuesday night and Wednesday, bringing a few rain and snow showers. Thanksgiving Day is expected to be dry with temperatures in the 30s.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH TUESDAY NIGHT/...
-- Changed Discussion --
As of 1247 PM EST Monday...well, still trying to play some catchup with the combo Lakes Superior/Huron snow band that has moved across northern NY and now into northern VT. The snowfall intensity and coverage has ended up being more than even the hi-res models indicated, at least here locally in the Champlain Valley and along the western slopes. Given that it`s snow, radar doesn`t detect it very well, so it wasn`t until it started snowing here in the Champlain Valley that we could "see" it on radar. Appears that there was some blocked flow that developed as well. That said, it appears that using the GOES-16 IR channel has been working well by using the -25C cloud top temperatures to show where the best snows are occurring. Over the last hour, the overall trend has been for cloud tops to start to warm. Although the hi-res models were doing fairly well earlier this morning, they have totally missed the snow here in the Champlain Valley and across the Green Mountains. Have tried to enhance coverage of the snow above what the models give, but even then, I`m still too low. Will probably continue to forecast chase the snow band over the next few hours. However, by this evening, wind flow will turn more southwest and be disruptive to the bands that are out there. So as we go on toward midnight, we will only be left with clouds and a few flurries, especially across northern NY. Southerly flow strengthens on Tuesday as the pressure gradient tightens due to high pressure moving off the coast, and our next weather system moving into the Great Lakes. Model soundings indicate 35-40 knots of wind between 925-850mb, especially in the Champlain Valley as topgraphically forced winds develop. Won`t mix down all of that to the surface, but it will result in a breezy day -- likely gusts to 30-35 mph. Southerly winds will bring in a warmer airmass, with highs well into the 40s across the region, even around 50F in the Champlain and St Lawrence Valleys. Precipitation ahead of a cold front will start moving into northern NY Tuesday evening, reaching the Champlain Valley by midnight. Boundary layer temperatures will be warm enough that it will be all rain, with snow only above 2500-3000 feet. The actual cold front will be a few hours behind the precipitation. So in the pre-dawn hours on Wednesday, expecting the rain to turn into snow showers across most of northern NY, with snow levels decreasing across Vermont.
-- End Changed Discussion --
&& .SHORT TERM /WEDNESDAY/... As of 239 AM EST Monday...Little change in the overall synoptic pattern is expected in the short term period where once again we`ll be dealing with another clipper low passing well north of the region, dragging a cold front through the area Tuesday night through Wednesday. Mild temperatures in the mid-30s to low-40s ahead of the front will support mainly rain in the valleys and a rain/snow mix at higher elevations as the boundary shifts into northern New York around midnight Wednesday, the morning rush in the Champlain Valley, and through eastern Vermont by mid-day. Behind the front, temps will gradually fall through the day with morning highs mainly in the mid/upper 30s, dropping to the upper 20s to mid 30s by sunset. Little to no snow accumulation is expected in the valleys, while elevations above 1000 feet may see a dusting to perhaps 2". && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 239 AM EST Monday...Extended period remains fairly active with breaks of high pressure in between more clipper lows passing north of the area through central Ontario and Quebec. Quiet weather is expected under high pressure for Wednesday night through Thanksgiving with seasonal to slightly below normal temps in the 30s/40s for highs and teens/20s for lows. First of 2 cold fronts to swing through the area arrives Thursday night into Friday with little fanfare as the parent low will track well north of the region, starving the boundary of any real deep moisture. Thus, while the probability of precipitation is high, the overall QPF is low with likely just some scattered snow showers and little accumulation if any. Brief high pressure builds back in for late Friday afternoon into early Friday night before the next front approaches. While several days out, this system looks similar to the one we just had this past weekend with strong warm air advection, gusty southwesterly winds and rain ahead of the cold front on Saturday, sharply falling temperatures, rain changing to snow showers and potential flash freeze Saturday night, followed by a cold, brisk Sunday. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
Through 18Z Tuesday...Flight conditions are all over the place thanks to a couple of bands of light snow. As an example, it`s IFR with 1/2sm in snow at BTV, while across the lake it`s P6SM BKN049 at PBG. These bands of snow will tend to slowly diminish over the next 6 hours as they stretch west to east and waver slightly north and south. Eventually, generally after 03z, conditions will transition to VFR most everywhere. May take until 06-08z for SLK and MSS for VFR. For Tuesday, primary weather item will be developing gusty south winds. Expecting 25-30kt gusts, especially in the Champlain Valley. Outlook... Tuesday Night: Mainly VFR, with local MVFR possible. Chance SHRA, Chance SHSN. Wednesday: Mainly VFR, with local MVFR possible. Chance SHRA, Chance SHSN. Wednesday Night: Mainly VFR, with local MVFR possible. NO SIG WX. Thanksgiving Day: Mainly VFR, with local MVFR possible. NO SIG WX. Thursday Night: Mainly VFR, with areas MVFR possible. Chance SHSN. Friday: Mainly VFR, with areas MVFR possible. Slight chance SHSN. Friday Night: Mainly VFR, with local MVFR possible. Chance SHRA, Slight chance SHSN. Saturday: Mainly VFR, with areas MVFR possible. Likely SHRA, Likely SHSN.
-- End Changed Discussion --
&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Evenson/Nash NEAR TERM...Nash SHORT TERM...Lahiff LONG TERM...Lahiff AVIATION...Nash

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.