textproduct: Burlington

WHAT HAS CHANGED

As of 115 PM EST Sunday...

A persistent north/south oriented lake enhanced band has brought a couple inches of snow as far south as Bridport. This feature will slowly wind down as the afternoon goes on. Mountain PoPs have increased slightly for Wednesday and Thursday associated with a closed low passing to our north.

KEY MESSAGES

As of 115 PM EST Sunday...

1. Temperatures continue below normal with no widespread precipitation over the next few days.

2. Wednesday through Sunday will feature several chances for snow showers as our region remains under influence of upper level troughing, then very cold conditions return to the region this weekend.

DISCUSSION

As of 115 PM EST Sunday...

KEY MESSAGE 1: The lake cloud that developed yesterday has lingered throughout the day Sunday. Bringing accumulating snow in the vicinity of Lake Champlain from Burton Island down through Bridport. We've received localized reports of a couple inches associated with this event. PoPs will start to drop this afternoon as the winds start to wane.

A persistent longwave trough remains the dominant feature through Tuesday. While daytime temperatures warm slightly Monday and Tuesday, the forecast still calls for below normal temperatures. Sunday night will once again bring temperatures near 0F. As the nor'easter moves further off shore surface high pressure will build back in. The associated subsidence inversion will allow daytime temperatures to reach into the teens and twenties Monday and Tuesday while suppressing any precipitation. A shortwave approaches from the west on Tuesday, bringing slight chance Pops into the Saint Lawrence Valley.

KEY MESSAGE 2: Upper level closed low is expected to swing through the region on Wednesday, just north of the international border, moving generally eastward. It's possible for some snow showers to develop that morning, mainly in higher terrain and upslope areas. There should also be a bit of cold air advection in west to northwest flow associated with low level surface low pressure rotating to our north and east. This will result in highs only in the upper teens and 20s for most. Thursday, current determinstic guidance contains varying solutions, but the main elements are that some cold air advection should be present in west to northwest flow, dry air dominates, and forcing is primarily aloft with no strong surface feature. Some solutions show only show some weak shortwave energy during this time, but the GFS in particular has a much deeper, closed low. The determinstic models also vary in the depth of cold air moving in. At the moment, it looks like any snow showers produced Thursday will be light, kept mostly in the mountains, and widely scattered due to the influx of dry air and potential lack of forcing.

Friday and Friday night, widespread snow showers associated with a third upper disturbance are likely, though models continue to shift the timing of this clipper system from run to run. The deterministic GFS is again more aggressive with the strength of a closed upper low pressure diving through New England, but on the ECMWF it would be a weak shortwave followed by a deeper, narrow axis of troughing as closed upper low stays well to our north. GFS also shows stronger and more well-defined surface low pressure moving through or just to the north of northern New York and Vermont while ECMWF dives primary surface low pressure across the Ohio Valley instead. Meanwhile, ensembles show a wide range of low tracks. One thing the determinstic and ensemble models agree on, however, is the influx of cold air following the system for the weekend. Projections of 850mb temperatures are as low as -32 to -25 C. Current forecast for surface temperatures is 5 to 15 degrees below zero at night and wind chills even lower.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

Through 18Z Monday...A few snow showers will linger this afternoon, then drier conditions will prevail tonight and Monday as surface high pressure drifts eastward towards northern New York and Vermont. There potential for low clouds and mist or freezing fog tonight into tomorrow morning. Currently, clouds are thinning across the region, resulting in clouds at 1100-2600 feet above ground level bouncing between SCT and BKN but gradually leaning towards SCT and FEW as well as rising in altitude this afternoon. SLK and EFK can expect to see clouds return this evening and tonight starting around 02Z-08Z Monday with cigs around 1500-3000 feet and a potential SCT layer around 400-1000 feet at SLK (possible at EFK but lower confidence) through about 12Z-14Z Monday. Elsewhere, VFR ceilings expected through 18Z Monday. Snow showers are possible in the Champlain Valley (30% chance at BTV and PBG) through around 20Z Sunday, then the remainder of the next 24 hours snow showers are not expected. There will also continue to be occasional wind gusts out of the north in the Champlain Valley as well as across parts of central Vermont (including MPV) of 15-25 knots through about 20Z Sunday, then winds overall see a decrease in intensity across the region, becoming light and variable or calm. Around 03Z through 14Z Monday, there is the potential for saturation of the lower levels of the atmosphere as temperatures fall towards relatively elevated crossover temperatures under clearing skies. At the moment, the most likely locations for some mist or even freezing fog are BTV, SLK, MPV, and EFK. SLK seems to have the highest probability of mist in general, including IFR conditions, as it is likely to have some kind of cloud layer at the 400-700 foot level that may sink lower under subsidence inversion and reach the surface at times. EFK also has some good model consensus on low level moisture and may act similarly. Outside of these two sites, though, model consensus is poor at the moment and it is unclear exactly how much saturation can take place and how low clouds can get.

Outlook...

Monday Night: VFR. NO SIG WX. Tuesday: Mainly VFR, with local MVFR possible. NO SIG WX. Tuesday Night: Mainly VFR, with areas MVFR possible. NO SIG WX. Wednesday: Mainly VFR, with local MVFR possible. Slight chance SHSN. Wednesday Night: VFR. NO SIG WX. Thursday: Mainly VFR, with local MVFR possible. NO SIG WX. Thursday Night: VFR. NO SIG WX. Friday: Mainly VFR, with local MVFR possible. Chance SN.

EQUIPMENT

NOAA Weather Radio station WXM-44, transmitting from Mt. Ascutney, Vermont, on frequency 162.475 MHz is non- operational at this time. NWS technicians have diagnosed the problem, but repairs will likely not be able to occur for quite some time due to circumstances beyond our control. Therefore, the time of return to service is currently unknown. The following NOAA Weather Radio transmitters may be able to provide service during this outage: WWG 50 from Burke Mtn, VT at 162.425 MHz and WNG 546 from Hanover, NH at 162.525 MHz.

The Colchester Reef meteorological station is out of service. This site is not serviced by the NWS and there isn't an estimated return to service at present. Use extra caution when navigating the broad waters of Lake Champlain. Please contact us if you observe winds significantly deviating from the recreational forecast.

BTV WATCHES/WARNINGS/ADVISORIES

VT...None. NY...None.