textproduct: Burlington

WHAT HAS CHANGED

As of 239 PM EDT Thursday...

Precipitation amounts are on the downward trend, with many models suggesting slightly lower QPF amounts than 24 hours ago. With this downward trend, ice accumulation is also looking more isolated, sticking to higher elevations and cold hollows east of the Greens.

KEY MESSAGES

As of 239 PM EDT Thursday...

1. Light wintry precipitation and light icing are likely in the mountains and much of Vermont east of the Green Mountains tonight and early Friday morning. Slick travel conditions are possible.

2. Unseasonably warm conditions expected Friday with showers, thunderstorms, and gusty winds as high as 35-45 knots likely in the Champlain Valley and higher elevations.

3. Another storm system will bring widespread, at times heavy, rainfall this weekend. The combination of this widespread rainfall and additional higher elevation snowmelt continues to bring the expectation of sharp river rises with low risk of reaching bankful.

4. Light snow showers and cooler conditions expected early next week, turning more seasonable by mid week.

DISCUSSION

As of 239 PM EDT Thursday...

KEY MESSAGE 1: This afternoon, high pressure is stationed across Quebec, New Brunswick, and Maine. Southerly flow aloft will be increasing into the evening hours as a low pressure system currently centered over the Plains shifts into the Great Lakes, then southeastern Ontario, tonight. Gradient winds will become enhanced as the low pressure approaches northern New York and Vermont, resulting in modest warm air advection and increased surface winds, particularly in north-south oriented valleys like the Champlain Valley where funneling may occur. A strong low level jet streak of up to 60-65 knots at 850 mb will also become directly overhead tonight, bringing with it the potential for southerly surface gusts up to 35-45 knots by early Friday morning. However, a low level inversion may limit some of the strongest gusts. Despite the warm air advection and southerly flow, we are expecting portions of the northern Adirondacks and Greens eastward in Vermont to hold onto cold air at the surface tonight due to Cold Air Damming. While the St. Lawrence and Champlain valleys will likely have temperatures in the mid 30s and 40s, most other spots will see lows fall into the lower 30s. As a result, as light precipitation spreads northeastward this evening, we'll see a minor freezing rain event develop in portions of central and eastern Vermont as well as the higher peaks and cold hollows of the Adirondacks. The degree of cold air will be fairly marginal such that it'll take time for temperatures to fall below freezing and this sub-freezing air will tend to settle in the mid-slopes of the Greens. Lower elevations, such as in the Upper Valley and in the vicinity of Lake Memphremagog, will likely stay just above freezing tonight. Overall ice accumulations will range from a light glaze to a quarter of an inch of ice possible at the highest peaks. Total precipitation amounts are expected to be in the 0.05-0.40" range, with highest amounts in the St. Lawrence Valley.

KEY MESSAGE 2: Southwesterly winds aloft will continue to blow across northern New York and Vermont on Friday, with 850 mb levels likely seeing 60-65 knots throughout the day. A deep low level inversion could limit how much of this mixes down to the surface, but high winds will be low enough in elevation that southerly surface gusts 35-45 knots seem likely in the Champlain Valley and at higher elevations on Friday morning. Temperatures on Friday are anticipated to reach the 60s for most despite lingering clouds and rain, which will be 15-20 degrees above seasonal normals for early April in this region. A few rumbles of thunder are likely given the warmth and passage of a couple frontal boundaries Friday. Winds will see a gradual decrease again Friday night as the jet moves eastward and high pressure noses in from Hudson Bay. Total rainfall amounts from Friday and Friday night are anticipated to be anywhere from a couple hundredths of an inch to a third of an inch, with highest amounts occurring in northern Vermont along the international border.

KEY MESSAGE 3: Cooler and drier northwesterly winds will filter in for Saturday, which has trended cooler but pleasant with highs in the mid 50s and lower 60s. Clouds will be on the increase ahead of the next storm system, which is likely to bring precipitation to northern New York by the end of the day, spreading to Vermont Saturday night from west to east. A narrow plume of deep moisture riding out ahead of cold front will ensure widespread rainfall that could be briefly heavy. The combination of this widespread rainfall and additional higher elevation snowmelt continues to bring the expectation of sharp river rises with low risk of reaching bankful. Southeasterly surface winds will increase Saturday night as the 850 mb jet reaches as high as 65-70 knots out of the southwest, though a deep low level inversion sets up again to limit mixing. Temperatures will remain relatively mild Saturday night in the upper 30s to mid 40s for most. On Sunday, a sharp frontal boundary will flip winds to a more westerly or southwesterly direction at the surface, and high temperatures look similar to Saturday. Total rainfall Saturday into Sunday is expected to reach around 0.30-1.10", with highest rainfall amounts in northern New York/the St. Lawrence Valley.

KEY MESSAGE 4: Upper level troughing behind a cold front Sunday will draw below average northwest Canadian air into the region with several lobes of embedded shortwave energy. The 540dm line will sink south of the region promoting both below average highs on Monday in the low 40s along with enough cold air in the mid to upper levels to sustain snow growth. Troughing riding along an area of high pressure across the Great Lakes will bring chances for snow showers, mainly diurnally driven, as the mid and upper levels cool with steepening lapse rates. With these steepening lapse rates, Monday afternoon will be breezy with occasional winds gusts around 20 MPH, weakening by Monday evening. Snow showers should be more confined to the northern Greens and Northeast Kingdom as well as the Adirondacks, but a flurry in the Champlain Valley cannot be ruled out. Temperatures in the deeper valleys and below 2000ft agl will not be conducive for any accumulation but rather some light flurries mixed with some light rain at times. Some summit levels may see a dusting to a tenth or two, but no impacts are expected. These showers will be very shallow with the equilibrium level only around 800mb further supporting little to no accumulations. Given the northwest flow, snow showers may persist into Tuesday, but by Tuesday night, high pressure will finally shift east from the Great Lakes bringing an end to any lingering snow showers. With the high pressure, temperatures will trend towards normal to above normal by mid to late week with some showers chances by late next week.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

Through 00Z Saturday...LLWS will be the main aviation threat this forecast period with some IFR/MVFR CIGs being the secondary threat. A low level jet slowly moves through the region overnight and tomorrow with 60kts in the 2000-5000ft layer resulting in both speed and directional shear promoting hazardous flying conditions. Otherwise, A mix of MVFR and VFR conditions currently prevail across the region this afternoon with ceilings generally between 2000 and 3500 ft AGL. While rain showers are expected across all terminals overnight, there is a small chance that eastern Vermont terminals could see freezing rain, although the chances are too small to include in the forecast. Ceilings will continue to lower overnight with the increased moisture, with most terminals between 1200 and 1500ft AGL by tomorrow morning, with some lingering mist leading to reduced visibilities. While winds stay up aloft overnight, there is a decent chance of some IFR at MPV/EFK/SLK; some was added 08-14Z. SFC winds will continue to strengthen throughout the TAF period, with gusts of 20 to 30 knots possible before speeds begin to taper down after 22Z.

Outlook...

Friday Night: Mainly VFR, with local MVFR possible. Slight chance SHRA. Saturday: VFR. Chance SHRA. Saturday Night: Mainly VFR, with areas MVFR possible. Windy with gusts to 30 kt. Definite SHRA. Sunday: MVFR/IFR conditions possible. Definite SHRA. Sunday Night: VFR. Chance SHSN, Slight chance SHRA. Monday: Mainly VFR, with areas MVFR possible. Slight chance SHSN. Monday Night: Mainly VFR, with areas MVFR possible. Slight chance SHSN. Tuesday: VFR. Slight chance SHSN.

EQUIPMENT

The Colchester Reef meteorological station is out of service. This site is not serviced by the NWS. An estimated return to service is May 1st. Please contact us if you observe winds significantly deviating from the recreational forecast.

BTV WATCHES/WARNINGS/ADVISORIES

VT...Winter Weather Advisory until 10 AM EDT Friday for VTZ003-004- 006>008-010-018>021. NY...None.