textproduct: Burlington

WHAT HAS CHANGED

As of 242 PM EST Wednesday...

A Winter Weather Advisory has been issued for the higher terrain of the Adirondacks and portions of the southern Green Mountains for Thursday and early Friday.

KEY MESSAGES

As of 242 PM EST Wednesday...

1. A coastal low will bring widespread lower elevation rain and wet snow mainly above 1200 feet with shower chances continuing through the weekend.

2. A few lingering showers Sunday, then high confidence in dry weather early next week.

DISCUSSION

As of 242 PM EST Wednesday...

KEY MESSAGE 1: Model consensus continues to favor a coastal type low to deepen and wrap moisture back across Vermont and northern New York Thursday with a more upslope regime developing by Friday. Temperatures and this pattern support lower elevation rain Thursday and mainly higher elevation snowfall before temperatures drop Thursday night promoting snow showers to most valley floors. The overall forecast remains quite tricky with balancing QPF timing, changing SLRs, and a shift in primary precipitation mechanisms while models struggle with the details.

Where the models continue to struggle are placement of the surface circulation, extent of northward moisture transport and QPF amounts, and amount of cold air in place across the region. The latest trends have pushed moisture back southward leaving more modest QPF across northern New York and Vermont representing nearly a 50% reduction to QPF from the previous forecast for many locations. As such, snow totals were decreased with most spots only seeing a dusting to around 1 inch, southern and Adirondack locations below 1200 feet receiving 1-2 inches, and 2-5 inches above 1200ft. This will primarily be a function of the period of heaviest precipitation period occurring over the daytime hours with snow ratios being lower due to thermal profiles. As such, snow will start at higher elevations and crash down to around 1000 feet over the evening hours as the low pulls away. The upslope regime begins Thursday night and continues through early Friday with higher snow ratios supporting more efficient accumulation rates, but hindered by decreasing moisture. Cooling profiles and dynamic cooling processes will help snow reach most valley locations overnight Thursday night and early Friday. However, it will be tough to get snow accumulations in lower valleys like the Champlain Valley given the relatively warm ground temperatures likely melting most, if not all, of the snow that reaches the ground Thursday night. For the St Lawrence Valley, most of the moisture will have exited before temperature profiles cool enough to allow snow to occur.

Behind the coastal low, northerly flow will remain through Saturday keeping shower chances ongoing, especially across terrain. One "gotcha" to watch out for will be the potential for streamers to form off of Lake Champlain producing some higher elevation snow showers. Temperatures over the weekend may be cooler as well depending on cloud cover which may keep highs lower. Valley highs over the weekend are favored in the lower 40s, but could decrease into the upper 30s if clouds proliferate off of Lake Champlain given continued cool air advection. Lows will be in the 20s for most spots.

KEY MESSAGE 2: The departing low will continue to pull away from the region Sunday, leading to continued northwesterly wrap-around flow with a few lingering showers. As the low exits, the depth of moisture will decrease throughout the day and shower coverage will further decrease from Saturday. Lower elevations will be mostly dry, while higher elevations Sunday will still see a few showers. Throughout the weekend, precipitation type will be elevation- dependent; snow levels will be generally between 1000 and 1500 ft. Higher elevations will pick up up to an additional inch over the weekend, with limited depth of moisture being the main limiting factor in larger wrap-around snow accumulations. Lower elevations should not expect any accumulating snow.

Monday onward, the forecast turns very quiet with high confidence in high pressure building in and larger diurnal temperature swings. Highs will be near seasonable normals, but lows will be chillier than normal, especially going into midweek.

AVIATION /00Z THURSDAY THROUGH MONDAY/

Through 00Z Friday...VFR ceilings will prevail through midnight, with cloud bases between 3000 and 8000 ft AGL. After midnight, ceilings will gradually lower, with ceilings becoming predominantly MVFR after 12Z. Rain and snow showers will spread into the area from southwest to northeast after 12Z Thursday. Precipitation type will be elevation dependent; snow levels will hover between 1000 and 2000 ft. Lowest flight conditions in the back half of the TAF period will be at KSLK and KRUT, where a trend towards IFR is expected after 12Z as precipitation and lower ceilings affect these terminals first. Winds will generally be light and variable through the next 24 hours.

Outlook...

Thursday Night: Mainly VFR, with local IFR possible. Definite RA, Chance SN. Friday: Mainly VFR, with areas MVFR possible. Chance SN, Chance RA. Friday Night: Mainly VFR, with areas MVFR possible. Slight chance RA, Slight chance SN. Saturday: Mainly MVFR, with local VFR possible. Chance RA, Chance SN. Saturday Night: Mainly MVFR, with local VFR possible. Chance SN, Chance RA. Sunday: MVFR. Chance RA, Chance SN. Sunday Night: Mainly MVFR, with areas VFR possible. Slight chance SN. Monday: Mainly VFR, with areas MVFR possible. NO SIG WX.

BTV WATCHES/WARNINGS/ADVISORIES

VT...Winter Weather Advisory from 10 AM Thursday to 10 AM EST Friday for VTZ018-019. NY...Winter Weather Advisory from 10 AM Thursday to 10 AM EST Friday for NYZ034.