textproduct: Burlington

WHAT HAS CHANGED

As of 150 PM EST Thursday...

Confidence is increasing in light upslope snow showers, with the potential for lower elevation flakes, late Friday through Sunday.

KEY MESSAGES

As of 150 PM EST Thursday...

1. Widespread lower elevation rain and wet snow above 1200ft will continue into tonight as a coastal low rotates south of the region through tomorrow.

2. Upslope snow showers will develop by late Friday for the northwest facing slopes of the Adirondacks and Greens, with some possible Lake Champlain enhanced precipitation in the Champlain Valley late Saturday into Sunday.

3. There is high confidence in drier and warmer conditions next week with high pressure building across the region.

DISCUSSION

As of 156 PM EST Thursday...

KEY MESSAGE 1: Current radar depicts our parent surface low occluding over western Pennsylvania this afternoon, with RAP surface analysis denoting the secondary coastal low beginning to deepen near the Delaware Bay. This secondary low will become the dominant system tonight into tomorrow with the better forcing and dynamics focused to our south. Models continue to shunt the best moisture profiles to our south where an axis of stronger frontogenesis looks to set up along Long Island to Cape Cod. That said, overrunning precipitation has already overspread much of southern Vermont this afternoon with road cameras showing snow falling across our higher elevations in the southern Greens, mainly above 1500ft. However, below 1500ft, into the area valleys, rain is expected to remain the dominant ptype through much of this event. Drier air along the International Border is helping to stifle much of the northward moisture extent, with precipitation amount trends lowering for areas north of US-2, and have since cut back on PoPs for these areas. Total snow amounts have come down slightly in the mountains with generally 2 to 4 inches, heavily tied to the terrain. A Winter Weather Advisory remains in effect until 10 AM Friday for eastern Addison and Rutland Counties in Vermont, as well as western Essex County in New York.

Into tonight, with the combination of dynamical cooling and nighttime cooling, some flakes may be able to mix into the the lower elevations like the Champlain and Connecticut River Valleys. Though surface temperatures in the aforementioned areas will remain at or just above freezing, limiting any accumulations to mainly just grassy surfaces. As the low continues to track east Friday, cyclonic north to northwest flow will develop and keep snow showers in the mountains as upslope snow.

KEY MESSAGE 2: North to northwest cyclonic flow will keep moisture wrapping around the coast low late Friday through early Sunday. As boundary layer temperatures cool with cold advection towards late Friday, orographic lift will help sustain snow showers in the upslope favored western facing slopes of the central and northern Greens and Adirondacks. In addition, with lake temperatures becoming 10C warmer than the advective cold air aloft, narrow lake enhanced snow showers may develop downstream of Lake Champlain overnight Friday and during the day Saturday. Areas that may see some additional rain/snow enhancement look to be in the areas along a line from Shelburne to Lincoln. The exact placement and actual development of such a mesoscale lake streamer are still uncertain, but dynamically this synoptic setup is favorable for Lake clouds and subsequent precipitation enhancement. Precipitation totals would be light in the aforementioned areas, with mainly rain northwest of Bristol, and perhaps some locally enhanced snow showers around an inch of snow near Bristol, Lincoln, and the Ripton areas.

Outside of the Lake enhanced showers, blocked flow will lead to snow showers along areas in eastern Chittenden and Franklin Counties in Vermont, and northern Franklin and eastern St. Lawrence Counties in New York. This second round of wintry weather looks to be more favorable for accumulations for our area, with snow levels hovering around 1000ft, and better dynamics. There is the potential for a mesoband to develop out of Ontario, with decent frontogenesis, and associated 50 to 100J/kg of cape in the Champlain Valley Saturday morning. If it materializes, brief accumulations are possible down to the valley floors due to dynamical cooling and an additional couple inches would be possible across the higher terrain. However, this should not significantly change the impacts. Any snow in the lower valleys would mainly be a coating to a slushy wet snow at this time. At this point, the snowfall looks too light to cause power outages but far southern Vermont will have to be watched in case the mesoband comes in and stalls there for a couple hours. The shortwave responsible for the upslope snow will swing south and exit the area late Sunday, with generally drying conditions by Monday morning.

KEY MESSAGE 3: Model consensus remains strong with little spread showing high pressure building across the Northeast next week. Most models support the ridge axis deflecting systems along a more northward track in central to northern Canadian latitudes. This will allow for some drying and warming through the week with highs generally in the 50s for most locations by Wednesday and most lows in the upper 20s to lower 30s. With ideal conditions for radiational cooling being likely, colder overnight temperatures should be anticipated for the usual colder hollows.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

Through 00Z Saturday...Surface low pressure passing well to our south is pushing some precipitation north up to about Middlebury, Vermont. Dry, north flow is keeping precipitation and lower ceilings suppressed south. Little change is expected, with perhaps a brief surge north in precipitation around 03z-10z. Only KRUT is likely to have prevailing precipitation, starting as rain, and gradually transitioning to snow. Any IFR ceilings will likely be limited to just KRUT, and it could fluctuate in and out of IFR between the dry, north winds and moisture near the surface low. These north winds will remain around 5-10 knots through the period. After 12z, any lingering snow should shift out of the area with VFR conditions with 5000-10000 ft agl ceilings. Some lowering ceilings will return after 20z.

Outlook...

Friday Night: Mainly VFR, with areas MVFR possible. NO SIG WX. Saturday: Mainly MVFR, with local VFR possible. Chance SHRA, Chance SHSN. Saturday Night: Mainly MVFR, with local IFR possible. Chance SHSN, Chance SHRA. Sunday: Mainly MVFR, with local VFR possible. Chance SHRA, Chance SHSN. Sunday Night: MVFR. NO SIG WX. Monday: Mainly VFR, with local MVFR possible. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: VFR. NO SIG WX.

BTV WATCHES/WARNINGS/ADVISORIES

VT...Winter Weather Advisory until 10 AM EST Friday for VTZ018-019. NY...Winter Weather Advisory until 10 AM EST Friday for NYZ034.