textproduct: Burlington

WHAT HAS CHANGED

As of 235 PM EDT Friday...

Snowfall has been increased across the high peaks of the Adirondack and Green Mountain ranges. Widespread frost is now expected Saturday night/Sunday morning and will likely result in frost headlines for portions of the Champlain Valley.

KEY MESSAGES

As of 235 PM EDT Friday...

1. Scattered rain showers with mountain snow showers expected tonight through Saturday morning.

2. Widespread frost expected Saturday night and Sunday morning with additional frost possible Sunday night.

3. Rainy and unsettled weather is expected much of next week.

DISCUSSION

As of 235 PM EDT Friday...

KEY MESSAGE 1: A shortwave disturbance tracking across the southern periphery of the upper level low is expected to bring scattered to numerous showers to the North Country and northern New York tonight. Surface temperatures are expected to be largely above freezing for the wider valleys but could see a few places in the NEK and northern Adirondacks to drop near or just below freezing tonight. While rainfall is expected below 1500 ft, we do expect some light snow to fall; especially across the high peaks of the Adirondack and Green Mountains. The latest high-res guidance has come in to show some decent liquid associated with the showers, especially across the Adirondacks, so we now expect 2-4 inches across the high peaks of the Adirondacks and 1-3 inches across the spine of the Green Mountains. It'll be a wet snow with model sounding showing a deep isothermal layer extending through the DGZ but shouldn't be overly that impactful with most snow falling above where most people live. High pressure is expected to nose in from the west Saturday afternoon which will bring an end to the precipitation with increasing sunshine as we move throughout the day.

KEY MESSAGE 2: We are looking at mostly clear skies and light winds Saturday night through Sunday. Strong raditional cooling is expected with overnight lows dropping into the mid 20s to mid 30s Saturday night which will be favorable for frost formation. Based on climatology, the growing season starts today (May 1st) for the Champlain Valley in NY and VT. Given the forecast of widespread frost Saturday night, we will likely need to issue our first frost advisory of the season but will hold off until tomorrow to issue if needed. Sunday will be on the drier side once again with afternoon RH values dipping into the mid 30s to mid 40s with winds generally in the 5-12 mph range. Recent rainfall has helped wet the fine fuels but we could see an increase in fire danger as we head into late this weekend but no critical fire weather conditions are expected. Cloud cover will begin to build back across the region Sunday night but we could see some frost across eastern Vermont during the first half of the overnight period prior to the clouds moving overhead.

KEY MESSAGE 3: After brief ridging on Monday, a large-scale trough gradually builds into the region during the rest of the week. It will be slow enough that a few different shortwaves will pass through and surface lows will develop along those. The first one passes well to the northwest on Tuesday. A weakening cold front will move into the region late Tuesday and bring a round of rain, particularly to northern New York. A brief rumble of thunder is possible in the afternoon. The next low passes through Wednesday with the center looking to track over the region. The final low looks to track through Thursday into Friday, with the center passing to the east of the region. There will be enough cold air on the backside of it that it could end as a few snow showers in the mountains. Through Friday, GEFS/EPS/CMCE combined ensemble probabilities of receiving 1 or more inches of rain are 80-100 percent, 2 or more inches are 30-50 percent, and 3 or more are 0-20 percent. Most of the precipitation should be stratiform and limit flooding concerns, but the effects of potentially three storm systems in a row will still be watched.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

Through 00Z Sunday...Scattered rain showers with mountain snow showers expected tonight through Saturday morning. A shortwave disturbance is expected to bring showery precipitation to northern New York and Vermont tonight. For the most part, precip will fall as rain and visibilities will be 3-6 miles or higher, but a few sites are situated just high enough in the mountains to have some snow mixing in, which could result in vis 2-4 miles or lower. Showers are likely to arrive around 06Z-09Z Saturday, and temperatures should cool enough at SLK for it to start as rain/snow mix. Precip looks to changeover to all snow there around 08Z-10Z Saturday. At MPV, precip should start as rain, then about 20-40% probability of some snow mixing in around 09Z-11Z Saturday. High pressure nosing in from the west will make showers more widely scattered by Saturday afternoon, any any lingering shower here and there should become only rain as temperatures get into the upper 40s to mid 50s on Saturday. In addition to potential visibility restrictions, we expect ceilings to decrease with the arrival of precipitation with widespread MVFR cigs likely by around 06Z-10Z Saturday. Low level moisture also suggests ceilings falling below 1000 feet above ground level at BTV, SLK, EFK, and RUT by 09Z-12Z Saturday. How long those IFR cigs linger is still in question, as there is little wind to scour them out on Saturday, but model soundings suggest atmospheric mixing will be enough to keep this bout of IFR relatively short-lived. Most projections have widespread MVFR cigs or higher by 14Z-16Z Saturday, lifting to VFR levels shortly after. As mentioned, winds will be light and variable over the next 24 hours, though a general northwesterly flow seems sustained through 00Z Sunday.

Outlook...

Saturday Night: VFR. NO SIG WX. Sunday: VFR. NO SIG WX. Sunday Night: Mainly VFR, with local MVFR possible. Chance SHRA. Monday: Mainly VFR, with local MVFR possible. Chance SHRA. Monday Night: VFR. Slight chance SHRA. Tuesday: Mainly VFR, with local MVFR possible. Chance SHRA, Slight chance TSRA. Tuesday Night: Mainly VFR, with local IFR possible. Chance SHRA. Wednesday: Mainly MVFR, with local IFR possible. Likely SHRA.

BTV WATCHES/WARNINGS/ADVISORIES

VT...None. NY...None.