textproduct: Burlington

WHAT HAS CHANGED

As of 158 AM EST Thursday...

Decrease in forecast ice amounts for tonight into Friday.

KEY MESSAGES

As of 158 AM EST Thursday...

1. Mixed precipitation tonight into Friday.

2. Rain Saturday preceded by pockets of freezing drizzle.

3. The potential for ice jams and localized hydrological related issues will need to be monitored this weekend thru the middle of next week due to the potential for record warm temperatures and significant snow melt.

DISCUSSION

As of 158 AM EST Thursday...

KEY MESSAGE 1: A weak system tracks northeastward toward the region late Thursday night into Friday. It will be running directly into a cold high trying to build southeast out of Canada. Right now, the center of the high looks to be too far east to keep the system to the south, but close enough to provide enough surface cold air to cause wintry precipitation. While temperatures should rise above freezing for many areas on Thursday, cold air will bleed down from the north during the day and cause a non-dirunal trend, especially for St. Lawrence and Champlain valleys, setting the stage for the wintry precipitation. The current expectation is that there is a notable warm nose Thursday night that causes the precipitation to start as a mix of rain, freezing rain and sleet. The warm nose looks to erode during the event and it should eventually transition to more of a rain/snow mix by the end for most places. It looks to change to snow first for much of Vermont and it could even begin as such at the onset in places. The sleet/freezing rain looks to last longer across northern New York where it may be the predominate precipitation type. Overall, models are starting to converge on a more southern storm track. This will lead to far northern areas seeing little if any precipitation. They are also trending toward a slightly cooler column, favoring a slightly quicker transition to snow. The decrease in forecast ice is mostly from the decrease in QPF. Overall, up to around a tenth of an inch of ice is possible in southern areas and up to around an inch of snow and sleet are expected. Power outages are not expected but locally slick travel is likely Thursday night into Friday morning.

KEY MESSAGE 2: An area of low pressure tracks over the Great Lakes into Canada Friday night and Saturday, as a Bermuda type high remains established off the coast. This sets the stage for strong warm air and moisture advection. However, surface cold air looks to remain entrenched east of the Greens Friday night into early Saturday as the antecedent cold high remains near Atlantic Canada. A few showers look to occur during this period, and abundant low level moisture could cause some areas of mist and drizzle. These could freeze in any of the cold hollows. Increasing winds Friday night should prevent significant fog from forming, but with the warm moist air over extensive snowpack it is still possible, especially in the protected hollows. Temperatures look to rise above freezing region wide early Saturday and eventually reach the 50s for most areas, with a run at 60 possible in the St. Lawrence Valley. While a couple showers are possible, most of the day should be dry. The cold front comes through late in the day and in the evening, bringing a line of potentially heavy showers. From a hydro perspective, the amount of rain should not be overly high. The line should be relatively fast moving and most of the day should be dry. However, combined with warm temperatures and dew points reaching the 40s, significant snowmelt will occur, though the fastest rates will be pretty short lived. Gusty southerly winds will occur on Saturday, with localized enhancements in the Champlain Valley due to channeling and in the northern Adirondacks due to downsloping. These winds will also enhance snowmelt.

KEY MESSAGE 3: The latest WPC forecast has been delivered and continues to indicate a period of much above normal temperatures for Monday thru Weds of next week. Little has changed with regards to the large scale synoptic features, which show Arctic high pres lingering over east-central Canada, while a strong Bermuda high pres is anchored acrs the SE CONUS. This places a sharp thermal boundary somewhere acrs our cwa for Sunday thru Weds of next week, with some wavering north and south anticipated. The key driver of the boundary location wl be strengthen, position and movement of Arctic high pres to our north. Latest guidance indicates strong southwest flow on Monday with progged 925mb temps btwn 8-12C, while weak boundary slips south for Tues, before a significant warm up redevelops for Weds. Progged 925mb temps from the GFS/ECMWF and CMC, along with the AI version of the GFS/ECMWF show values in the 12C to 16C range on Weds, which could easily support highs in the upper 50s to upper 60s, maybe near 70F depending upon clouds/frontal timing. For now no change has been made to the WPC temps, which indicate highs mostly in the 50s and lows in the upper 20s to mid 30s. Also, several progged southwest 850mb jets of 45 to 60 knots wl be associated with the waa, so anticipate gusty winds at times, especially summits, northern Dacks and parts of the CPV.

This long duration warm up will result in significant snow melt acrs all elevations, increasing the risk of sharp river rises and ice jam related flooding. First threat of ice jam flooding will occur on Saturday into Sunday due to combination of snow melt and qpf with cold frnt. Thinking isolated ice jam flooding is possible on the Salmon, Ausable, Otter Creek, and Mad River. Meanwhile, the threat for additional ice jam related flooding wl shift into central/northern rivers by early to middle of next week, including the Salmon, Chazy, Lamoille, Missisquio, and Winooski. Latest NAEFS and GEFS show 70 to 95% probability of Otter Creek, Ausable, Mad and Winooski reaching action stage, with 50 to 75% probability of these rivers reaching minor flood stage by the middle of next week. I do think the snow melt contribution into the rises is a bit too aggressive, but the general idea of ice jam flooding and isolated/localized flooding will be possible on Saturday/Sunday and again the middle of next week. If confidence continues to increase a flood watch for ice jam related flooding maybe needed in later forecasts. The good thing is qpf is only expected to be in the 0.25 to 0.75 range associated with boundary, but if a wave develops this could be enhanced.

AVIATION /12Z THURSDAY THROUGH MONDAY/

Through 12Z Friday...A very challenging aviation forecast with regards to low clouds and potential IFR cigs. A cold front continues to push south across our taf sites this morning with a wind shift to the north/northeast. Meanwhile, the GOES-19 fog product is showing areas of low level stratus developing, especially near EFK/BTV and PBG as thermal inversion strengthens. This low level moisture, combined with blocked northerly flow should support intervals of IFR cigs at BTV/EFK and possibly PBG thru this morning. Difficult to determine if clouds wl advect into the Rutland area, as they are progged to keep more of a southeast wind flow. Also, some areas of mist/low clouds possible for a few hours this morning at SLK/MPV. Clouds lift to MVFR/VFR for several hours late morning into early afternoon, before lowering back toward IFR/MVFR conditions this evening. A wintry mix of snow/sleet is expected at RUT toward 03z with some light snow and ice accumulation likely. Also, breezy northeast wind gusts up to 25 knots expected at MSS this morning.

Outlook...

Friday: Mainly VFR, with areas MVFR possible. NO SIG WX. Friday Night: Mainly MVFR, with local VFR possible. Chance RA, Chance FZRA. Saturday: Mainly MVFR, with local IFR possible. Windy with gusts to 30 kt. Chance RA, Chance SHRA, Chance FZRA, Slight chance TSRA. Saturday Night: Mainly IFR, with areas MVFR possible. Likely SHRA, Slight chance RA. Sunday: Mainly VFR, with local IFR possible. NO SIG WX. Sunday Night: VFR. NO SIG WX. Monday: VFR. NO SIG WX.

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...Winter Weather Advisory from 7 PM this evening to 1 PM EST Friday for VTZ009-011-018-019. NY...Winter Weather Advisory from 7 PM this evening to 1 PM EST Friday for NYZ029-030-034-087.