textproduct: Burlington

WHAT HAS CHANGED

As of 458 PM EDT Friday...

No significant changes were made with this forecast package.

KEY MESSAGES

As of 458 PM EDT Friday...

1. A highly elevation dependent snowfall develops by this evening with areas of slick travel expected overnight, along with periods of gusty winds and lingering upslope snow showers on Saturday.

2. Multifaceted storm system expected to impact the region Sunday and Monday.

3. Cooler and unsettled weather expected through late next week.

DISCUSSION

As of 458 PM EDT Friday...

KEY MESSAGE 1: A Winter Weather Advisory continues for a highly elevation dependent snowfall for the Adirondacks and portions of the southern Greens, with accumulations ranging from a dusting to 1 inch acrs the CPV/lower CT River to 6 to 10 inches at summit level by Sat evening.

GOES-19 water vapor indicates dynamic clipper system over the central Great Lakes this aftn with initial waa lift/moisture and associated precip band angling into western/central NY attm. Sfc analysis places 987mb low pres over northern MI, with greatest 3 hr pres falls toward the eastern Great Lakes/SLV. Sfc low pres wl quickly track along the International Border late tonight into Saturday with several rounds of snow showers anticipated. First round this evening wl be associated with moderately strong 850 to 700mb waa lift/moisture moving from southwest to northeast. A burst of moderate snow is likely btwn 22z-04z acrs our region with a quick dusting to 2 or 3 inches expected, highest over the summits of northern NY and VT. Good news the heaviest period of snowfall should occur after the Friday evening commute. Brief mid lvl dry slot angles toward our central/southern cwa around midnight, with decreasing areal coverage of snow shower activity anticipated. A secondary band of enhanced 850 to 700mb fgen forcing develops ahead of dampening but potent 5h s/w energy, along with a pocket of weak instability. The locally developed snow squall parameter indicates values in the 2 to 5 range over southern VT, suggesting some convective snow showers with fropa on early Sat morning.

Meanwhile, as sfc low pres tracks to our east by midday Saturday, favorable upslope 925mb to 850mb flow develops, along with better 925mb to 500mb rh progs >80% behind the dry slot with trrn enhanced snow showers redeveloping. As bl temps warm into the mid/upper 30s on Saturday aftn, the best potential for accumulating snowfall wl be above 1800 feet on Saturday aftn. However, with bl heating, instability redevelops with sfc based cape values in the 40 to 120 J/kg range with the snow squall parameter values in the 2 to 5 range again, especially central/northern VT, including the NEK. Expecting disorganized convective snow showers with the potential for a few embedded heavier snow squalls, with some graupel/snow pellets possible on Sat aftn. Within the heavier cores, a quick coating could occur, briefing resulting in very localized hazardous travel. Given strengthening 925mb to 850mb southwest jet tonight and warming bl temps above 32F on Saturday, expected a sharp elevation depend snowfall. Amounts range from a dusting to an inch or so here in the CPV and Lower CT River Valley to 2 to 4 inches SLV and parts of the NEK with 6 to 10 inches for the summits of the northern Dacks and central/northern Greens by Sat evening. No expansion of the advisory is necessary as impacts wl be mostly for slick travel tonight into Saturday morning, before warming temps into the 30s and high mid March sun angle quickly melts any snow on road surfaces.

Several intervals of gusty winds are anticipated over the next 12 to 36 hours acrs portions of our cwa. First is tonight associated with developing south/southeast 925mb to 850mb jet of 35 to 50 knots, which given inversion height, should produce localized gusts in the 30 to 40 mph range acrs the northern CPV and parts of western slopes. Next window for gusty winds wl be on the backside associated with west/northwest 850mb jet of 40 to 45 knots and deeper mixing profiles under llvl caa. This supports localized gusts 35 to 40 mph acrs northern/eastern Dacks and east side of the Greens and portions of the NEK of VT late Sat into Sat evening.

Sunday is quiet with near normal temps and maybe a few lingering mtn flurries. Winds and moisture increase on Sunday night ahead of our next powerful storm system for early next week. Given low level cold air trapped east of the Greens, a period of light freezing rain is possible on Sunday night, along with developing gusty ridgetop winds of 45 to 60 knots.

KEY MESSAGE 2: A warm front will lift north across the region on Sunday with an impressive surge of warm air expected to situate across Vermont and northern New York on Monday. Models continue to back off on precipitation chances associated with the warm front as PWATS of 0.30" or less will be in place ahead of the front. The NAM and GFS continue to show a decent areas of FGEN associated with the leading edge of the warm front, but the higher PWAT airmass will lag behind the frontal boundary. There is still chance we could see some mixed precipitation right along the leading edge of the warm front but given latest model trends, that probability is now only upwards of 20%.

There is some disagreement amongst deterministic guidance regarding the dry slot that develops in the wake of the warm front late Sunday into Monday with some guidance showing some shower activity while others remain much drier. The reason for the disagreement is a low amplitude shortwave that is expected to move north towards New England within the meridional upper level flow. The lower res global guidance has a hard time depicting these smaller scale features and each run this shortwave bounces further west or east. Once this feature develops, likely on Sunday, models will have a much better idea on the overall track of this feature and the orientation of the longwave pattern. The reason this could have a sizable impact on the forecast is that the showers, or lack thereof, could impact the overall warming on Monday. Right now, it's looking likely we warm into the upper 50s to mid 60s but would likely be significantly less if we have to contend with showers. More on this in a minute.

Within the dry sector or Monday, a very strong (60+ knots) low level jet is expected to set up across the region. It's very difficult to determine how much, if any, of this low level jet is able to mix down to the surface as the warm front from Sunday will likely set up a huge surface based inversion. Now, as mentioned earlier, if we are able to warm into the 60s, we could see mixing up to about 900 mb which would be supportive of some of these stronger winds making it down to the surface with 45-50 mph winds not out of the question. If we are cooler, there will be less mixing and less winds. It's a very challenging forecast as the strongest winds remain just off the surface and if we can tap into them at all.

A cold front will sweep through the region Monday night through Tuesday morning with a period of moderate to heavy rain possible along the leading edge of the cold front. A sharp thermal gradient (30+ degrees F) will be seen just ahead and behind of the cold front which will result in high FGEN values. CAPE will be limited to maybe 100-200 J/kg but the forcing is likely high enough that a few rumbles of thunder cannot be ruled out. The latest ensemble blends show about 0.5 to 1 inch of snow across much of our forecast area. With river flows already on the high side and ice on some areal rivers, some isolated flooding cannot be ruled out at this time.

KEY MESSAGE 3: Following the cold front on Monday and Tuesday, much cooler and seasonal air is expected back across the North Country and northern New York. A deep upper level trough will settle into the region late Tuesday and begin to lift north on Thursday. High temperatures will struggle to climb into the low to mid 30s on Tuesday and Wednesday with temperatures moderating back to normal values on Thursday once the trough begins to lift north. With steep lapse rates in place in response to the very cold air aloft, chance for occasional snow showers with low amplitude shortwave energy will remain possible but no significant weather is expected through the end of the week.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

Through 00Z Sunday...VFR conditions remain pervasive despite snow showers spreading across the region. This is primarily due to drier surface air resulting in higher flight categories. Waves of showers will thicken, however with IFR visibility becoming more frequent. The snow showers will gradually become lighter and more scattered after midnight, and any consistent IFR visibility should be done. A few on and off snow showers will continue through the rest of the night and for much of tomorrow, with SLK, MSS and EFK seeing the greatest frequency of snow showers. Periods of IFR and MVFR visibility should occur during this time, though a majority of the time conditions should be VFR. Snow showers end tomorrow afternoon. Winds during snow showers will remain slower but will increase again as low pressure tracks eastward resulting in more frequent gusts to 25kts. Winds decrease in the later part of the night and tomorrow morning. Winds will be mostly southerly for the first part of the night, before becoming more southwesterly and westerly as they diminish. They become northwesterly and increase again tomorrow afternoon. Northwest flow will likely result in upslope snow showers. MVFR CIGS may be the main threat to aviators during the day on Saturday.

Outlook...

Saturday Night: Mainly VFR, with local MVFR possible. Windy with gusts to 30 kt. Chance SHSN. Sunday: VFR. Chance SHRA, Chance SHSN. Sunday Night: Mainly VFR, with local MVFR possible. Strong winds with gusts to 40 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 local IFR possible. Windy with gusts to 30 kt. Definite SHRA. Tuesday: Mainly VFR, with local MVFR possible. Windy with gusts to 30 kt. Slight chance SHSN. Tuesday Night: VFR. NO SIG WX. Wednesday: VFR. NO SIG WX.

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...Winter Weather Advisory until 2 PM EDT Saturday for VTZ019-020. NY...Winter Weather Advisory until 2 PM EDT Saturday for NYZ029-030- 034.