textproduct: Burlington

WHAT HAS CHANGED

As of 243 PM EDT Saturday...

High Wind Watch issued for portions of northern NY from 00z Sunday until 00z Tuesday.

KEY MESSAGES

As of 243 PM EDT Saturday...

1. High Wind Watch for portions of northern NY from 00z Sunday until 00z Tuesday for potential gusts up to 60 mph and scattered power outages possible.

2. Pockets of freezing rain expected east of the Green late Sunday evening into Monday, which could cause areas of slick travel during the Monday morning commute.

3. A strong cold front will bring very changeable conditions Monday night into Tuesday, with rapidly falling temperatures and rain turning to snow. Travel impacts due to flash freeze and/or black ice are possible. River rises likely but flooding not anticipated at this time.

4. Seasonable weather expected for the latter half of next week, with a few chances for showers.

DISCUSSION

As of 243 PM EDT Saturday...

Rest of Today...NWS radar imagery is showing a rapid development of snow showers along the Western Slopes this aftn with dBZ returns in the 30 to 35 range. Per latest webcams at Nashville and Westford a quick coat to 1 inch or 2 of snow has occurred on grassy surfaces. These instability driven snow showers along a sfc cold frnt wl continue for several more hours as they slowly move thru central/northern VT. The snow squall parameter still indicates values in the 2 to 5 range, supporting localized heavier snow showers or embedded snow squalls. In addition, as winds shift to the west/northwest behind the boundary a period of upslope snow showers wl lingering into the evening hours. Localized snowfall of 1 to 3 inches possible with some higher amounts possible above 1500 feet near the Green Mountain Spine. Some slick travel is possible in the heavier convective snow elements.

KEY MESSAGE 1: A powerful 980mb low pres is expected to move from the central MS River Valley into the central Great Lakes by 12z Monday with a strengthening 925mb to 850mb wind field acrs our cwa. A very challenging fcst in regards to mixing, wind direction and timing of strongest winds. The greatest confidence of wind gusts up to 60 mph is acrs the northern Dacks from near Malone to Ellenburg, while 35 to 50 mph wind gusts are possible along the western slopes and portions of the CPV. Wind advisory wl likely be needed outside the watch to cover this potential.

As 980mb low pres lifts acrs the central Great Lakes multiple 925mb to 850mb jet cores impact our cwa from 00z Monday thru 00z Tues. The first core is roughly btwn 00z and 09z Monday, with progged 925mb winds of 70 to 75 knots along the northern Dacks, while 850mb winds are 75 to 80 knots per latest 12z NAM3KM. RAP sounding data near Malone indicates top of the mixed layer winds of 65 knots, which supports localized gusts in the 55 to 65 mph range. Meanwhile, a secondary maximum wind gust threat is possible along the western slopes, where progged 925mb winds are 60 to 65 knots, but directly is a bit southerly to support max mixing. In addition, expanding precip on southerly flow may help to stabilize boundary layer during maximum low level jet acrs parts of VT. Initial thoughts is that a wind advisory wl likely be needed for the western slopes and northern CPV.

Meanwhile, as a sharp sfc cold frnt associated with low pres approaches our cwa late Monday aftn, progged southerly 850mb wind fields restrengthen btwn 70 and 85 knots, especially in VT. Additional gusty winds are likely, especially with deeper mixing profiles with temps warming into the upper 50s to mid 60s on Monday aftn. Southerly winds would be strongest acrs the northern/central CPV and midslope/ridges of central/northern VT. Some question with regards to mixing over the frozen/cooler Lake Champlain waters on Monday aftn. Progged 925mb temps surge btwn 12-14C on Monday aftn, should support highs near 70F at Malone, 65F at BTV and mid/upper 50s east of the Greens, where low level maritime airmass maybe hard to dislodge.

KEY MESSAGE 2: The combination of developing southerly moisture advection btwn 850mb and 500mb and low level southeasterly Atlantic moisture advection wl produce a period of light rain with pockets of freezing rain possible on Sunday night into Monday morning. Low lvl cold air wl remain trapped in the deeper/protected valleys of VT, where bl temps wl hover btwn 29-32F, supporting the light freezing rain potential. Any ice accumulation wl be <0.10" and travel impacts should be localized. A sps or winter wx advisory wl probably be needed to coverage this potential on Sunday night into Monday morning with some impacts to the AM commute possible.

KEY MESSAGE 3: Monday's low pressure system will continue to lift up to our west and eventually pass by to our north Monday night, dragging a strong cold front along in its wake. While strong south winds and very mild temperatures will exist ahead of the front, conditions will change very quickly as the front moves through. Temperatures will plummet some 15-20 degrees with the frontal passage, quickly changing rain over to snow. There could be a period of wintry mix of snow, sleet, and freezing rain during the transition, but expect this will be fairly brief and transient in nature. Widespread snow will exit by around daybreak Tuesday, but expect mountain snow showers to redevelop during the day, mainly in the favored upslope areas of the northern Adirondacks and western slopes of the Green Mountains. Most areas will get an inch or less of snow accumulation, though the northern mountains will see more like 2-4 inches or so. Still, wet roads and other surfaces could freeze overnight Monday night as temperatures drop below freezing, resulting in a layer of ice below any snow accumulation. Hence travel could be hazardous, including for the Tuesday morning commute. Because rain will be relatively short lived due to the fast forward motion of the cold front, don't anticipate a whole lot of liquid precipitation with this system. And since we've lost a lot of our snowpack, don't anticipate any flooding issues at this time. However, we'll still need to watch for any ice movement/jams on waterways in the Northeast Kingdom and far northern NY.

Winds will also be a concern and could add to travel woes. Although not as strong as what we'll see on Monday, winds will still quite gusty Monday night and Tuesday, from the west/southwest. This could serve to further lower visibilities in any snow, especially as ratios increase later Monday night into Tuesday morning. Gusts of 25 to 35 mph are expected. Highs will only be in the 20s Tuesday, so wind chills will definitely be on the cold side, in the single digits and teens.

KEY MESSAGE 4: Although Wednesday will be cold, temperatures should gradually increase through the end of next week, with highs in the 30s and 40s and lows in the teens and 20s by the weekend. High pressure will give us a couple of dry days mid week, but then shower chances increase as a couple of upper shortwave troughs scoot through the nearly zonal flow aloft. There's still some uncertainty with the timing of these systems, so have stayed close to WPC's forecast for Wednesday and beyond.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

Through 18Z Sunday...Scattered snow showers will persist through the first 4-6 hours of the TAF period. MVFR/IFR conditions likely in any showers, with visibilities reduced to 2-4SM (1-2SM at KSLK) and ceilings generally 1200-2800 ft. Snow showers end by 00z, though ceilings will be slower to respond, remaining 1500-3500 before slowly eroding and lifting after 04z. VFR expected for the remainder of the TAF period thereafter, with mid-clouds increasing after 14z Sun. SW/W winds 8- 12 kt with gusts 18-24 kt this afternoon will gradually abate after sunset, becoming light and variable by 06z.

Outlook...

Sunday Night: Mainly VFR, with local MVFR possible. Windy with gusts to 35 kt. Chance RA, Slight chance FZRA. Monday: Mainly MVFR, with local IFR possible. Windy with gusts to 35 kt. Definite RA. Monday Night: Mainly MVFR, with areas IFR possible. Windy with gusts to 35 kt. Definite SHRA, Chance SHSN. Tuesday: VFR. Windy with gusts to 35 kt. Slight chance SHSN. Tuesday Night: VFR. Slight chance SHSN. Wednesday: VFR. NO SIG WX. Wednesday Night: Mainly VFR, with local MVFR possible. Slight chance SHSN. Thursday: Mainly VFR, with areas MVFR possible. Slight chance SHRA.

EQUIPMENT

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...High Wind Watch from Sunday evening through Monday evening for NYZ027-030-031-034.