textproduct: Burlington

WHAT HAS CHANGED

As of 240 AM EDT Monday...

A Wind Advisory has been issued for the St. Lawrence Valley today.

KEY MESSAGES

As of 240 AM EDT Monday...

1. Localized ice jam flooding should continue and open water flooding is possible mid-week.

2. Gusty winds today.

3. A storm system passes through Wednesday into Thursday, bringing widespread precipitation.

4. More active weather expected over the weekend.

DISCUSSION

As of 240 AM EDT Monday...

KEY MESSAGE 1: Ice breakup on rivers began in many places yesterday, and with continued mild temperatures into Wednesday, most rivers should see ice movement by then. Ice jams formed yesterday in a few of the favored locations and remain in place. Currently, the Ausable, Great Chazy, Mad and Missisquoi Rivers have ice jams with some water backing up behind them. While some field and low lying flooding has been observed and is still occurring, no significant flooding has happened over roadways or into structures, other than over a couple roads in floodplains. As ice breakup continues during the next couple days, a few ice jams will likely to continue to form. Thankfully, no rain is expected through Tuesday and cool temperatures overnight will lower snowmelt. Therefore, there will be some room for water to rise behind any jams that form before rivers reach bankfull, so any flooding would likely continue to be on the minor side. However, with the unpredictable nature of ice jams more significant flooding cannot be ruled out. Due to the lack of rain, open water flooding is not expected through Tuesday.

The next chance for open water flooding comes Wednesday into Thursday. However, the details are uncertain due to uncertainty in storm track. There will be a sharp temperature gradient situated across the region, so a northerly track would lead to warm rain and significant snowmelt, and a southerly track would lead to mixed precipitation and little snowmelt. In the former scenario, minor to moderate flooding would be possible, mostly in the typical spots on the Otter Creek, and on the Mad, Ausable and Winooski Rivers. A southerly storm track would lead to mixed precipitation and little flooding. In either scenario, widespread major flooding is not expected. Most rivers will likely have flushed most of their ice before then so many areas should not have to contend with ice jams, but a few rivers may have lingering ice problems.

KEY MESSAGE 2: A southwesterly low level jet passes overhead today, with the peak magnitude over northern New York. Gusts in the 35-50 mph range are possible in the St. Lawrence Valley due to channeling, while they should generally be between 20-35 mph elsewhere. Winds in the 50-60 KT range at the top of the mixed layer and a relatively mixed profile should allow 50 mph gusts to reach the ground in the St. Lawrence Valley. There could be a couple isolated power outages in the areas that see the strongest winds.

KEY MESSAGE 3: A low will track northeast into the region Wednesday into Thursday, bringing multiple rounds of precipitation. While ensemble guidance is in relatively good agreement on the overall storm track, a sharp temperature gradient will set up so a change in even 50 miles in track could mean the difference between 55 and showery and 30 and freezing rain, and there is still too much spread to give the exact position of the boundary. A cold high will attempt to build south out of Canada Tuesday night into Wednesday and surface cold air looks to drain down into the St. Lawrence and northern Champlain Valleys. A warm front will then move into the region with a line of west to east oriented precipitation. Freezing rain is possible in the northern valleys during this feature, and whether the cold air continues to drain farther south or is forced back north remains uncertain. Southern areas should see mostly dry conditions and a few rain showers. The center of the low passes through Wednesday night. A line of rain is expected for most places with this and it could end as a brief period of snow. The only place that currently looks like it could see significant icing is parts of the St. lawrence Valley, but the extent of that remains uncertain. The warm temperatures and rain south of the boundary will cause a flood threat.

KEY MESSAGE 4: Temperatures trend towards seasonal normals from Thursday night through Monday night, and there will be a couple chances for precipitation Friday into Saturday and again Sunday into Monday. A clipper low will cross our area on Friday into Saturday bringing widespread light snowfall to our region. Borderline daytime temperatures will mean a mix of rain and snow for the warmer valleys where the high temperatures will be above freezing. Overnight it should be cold enough for light snowfall accumulations areawide. Will not have too much of a break in the action as a warm front lifts into our area on Sunday. Too far out for details at the moment, but this system could bring a chance for some mixed precipitation, then a change back over to snow as cold front sweeps across our area Sunday night into Monday. Details are quite unclear with these systems as they are so far out in the forecast period.

AVIATION /12Z MONDAY THROUGH FRIDAY/

Through 12Z Tuesday...VFR conditions will prevail over the next 24 hours. Winds are the main concern through the entire period. South to southwest winds of 5-13 knots. Winds aloft remain out of the southwest to west at 35-45 knots. Winds will remain fairly light through 14z, but surface winds and winds at 2000 ft agl will increase again during the day. This will be most notable at KMSS, where southwest winds will increase to 20 knots sustained with gusts up to 35 knots or slightly higher. Winds will start to let up in the evening and into the overnight.

Outlook...

Tuesday: Mainly VFR, with local MVFR possible. NO SIG WX. Tuesday Night: Mainly MVFR, with local IFR possible. Chance RA, Likely FZRA. Wednesday: Mainly MVFR, with areas IFR possible. Definite RA, Definite FZRA. Wednesday Night: Mainly MVFR, with areas IFR possible. Definite RA. Thursday: Mainly VFR, with areas MVFR possible. Chance SN, Chance RA. Thursday Night: VFR. Slight chance SN. Friday: VFR. Chance SN.

CLIMATE

Record High Minimum temperatures today are possible at Plattsburgh (PBG) and Burlington (BTV). Below are the records that may be broken or tied.

BTV: 41/2012 PBG: 39/1973

Record High Maximum temperatures are possible on Tuesday (Monday records are less likely to be broken). As of now, this is favored at Montpelier (MPV) and the current record is:

MPV: 60/2016

EQUIPMENT

The KBTV ASOS has suffered a communications failure. The issue has been diagnosed, but there is currently no estimated time of return to service. The affected communications line is not serviced by the NWS. Terminal Aerodrome Forecasts will continue, but regular observations may not be available.

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. Please contact us if you observe winds significantly deviating from the recreational forecast.

BTV WATCHES/WARNINGS/ADVISORIES

VT...None. NY...Wind Advisory until 6 PM EDT this evening for NYZ026-027-087.