textproduct: Burlington

WHAT HAS CHANGED

As of 721 PM EDT Friday...

Minor update to tweak temperatures and dewpoints based on observations. Late afternoon/early evening temperatures were slightly warmer than initially anticipated, but with clear skies and light winds, overnight lows in the 40s are on track.

KEY MESSAGES

As of 233 PM EDT Friday...

1. A frontal system will bring breezy conditions on Saturday, followed by widespread rain showers and much cooler temperatures. Rain will turn to snow over higher elevations, with some accumulation expected.

2. Turning much colder for the start of the work week, with temperatures well below normal.

3. Mid to late next week looks mostly dry with gradually increasing temperatures.

DISCUSSION

As of 233 PM EDT Friday...

KEY MESSAGE 1: Clearing skies this afternoon will give way to partly to mostly clear conditions this evening and overnight. Clouds slowly increase Saturday as flow turns to the south/southwest ahead of an incoming upper trough and associated low pressure system. Moisture and temperatures will both increase in response. Highs will mainly be in the mid 60s to mid 70s from the Champlain Valley westward with south/southwest winds of 10 to 15 mph with gusts of 25 to 35 mph are expected, strongest in the the Champlain and St Lawrence Valleys. Meanwhile, low level flow will be more southeast east of the Greens, keeping those areas a bit cooler; highs there will top out in the upper 50s to low 60s.

The front makes its approach late in the day Saturday, then moves through Saturday night into Sunday. As mentioned, moisture will surge ahead of the front; PWATs will approach or exceed 1.25 inch. This is a bit lower than what models were indicating 24 hours ago, but still within the 97-99th percentile for April. Instability will be fairly meager due to sub-optimal overnight timing and a warm layer at 850 mb, but there could be some heavy rainfall rates at times, perhaps around 0.50 in/hr. The temperature forecast remains tricky, as temperatures will fall sharply behind the front, while south flow will cause temperatures to rise or hold steady ahead of the front, particularly in the Champlain Valley. By the time the front exits to our southeast mid-morning Sunday, temperatures will range from the mid/upper 30s in the Adirondacks/St Lawrence Valley, while areas from the Champlain Valley eastward will be in the mid to upper 40s. This all comes crashing down through the day though as cold air rushes in behind the front. Although precipitation may wane a bit overnight Saturday night, expect another surge of moisture on Sunday as a wave of low pressure rides along the front. Therefore, given the falling temperatures, rain will transition to snow, mainly at higher elevations as snow levels fall to 1200-1800 ft by sunset Sunday evening. However, any appreciable snow accumulation should remain confined above 2000 ft, where a few inches will be possible. Elsewhere, accumulation would be just a few tenths at most. Winds will turn to the west and remain gusty behind the front as well, resulting in wind chills in the upper 20s to mid 30s. All in all, expect a raw, damp, and breezy end to the weekend.

KEY MESSAGE 2: A secondary cold front will cross the region late Sunday into Sunday night, bringing a reinforcing shot of colder and drier air. Any lingering snow showers will come to an end by early Monday morning, with only minimal additional accumulations in the higher terrain of the northern/central Green Mountains. Temperatures will plummet into the 20s to near 30F by daybreak Monday. Monday will be dry with high pressure building overhead, though it will remain quite chilly. Highs will only be in the mid 30s to mid 40s, some 10- 15 degrees below normal. North to northwest winds will be on the breezy side, 10 to 15 mph gusting up to 25 mph. As such, it'll feel quite a bit colder during the day as wind chills will be in the mid 20s to mid 30s.

KEY MESSAGE 3: Large scale troughing will generally be in place for the middle and end of next week, keeping temperatures around and slightly below climatological normals. The one precipitation chance will be when a shortwave passes through sometime Tuesday into Wednesday but precipitation will be relatively light. There should be snow showers in the mountains and rain showers in the lower elevations, but the exact snow levels are uncertain at this time. During the time with the most precipitation, the NBM probability of snow levels below 1,000 feet are generally between 10 to 30 percent. Below 3,000 feet they are between 60 to 80 percent. In all, any accumulations would likely be restricted to the high terrain and very minor.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

Through 00Z Sunday...Widespread VFR conditions are expected to predominate over the next 24 hours. High pressure initially overhead tonight will shift east early Saturday, resulting in increasing southerly return flow through the day. For TAF sites, this will translate to light and variable winds through 12Z, followed by increasing south winds with some gusts 25-30 knots developing after 12Z. Some marginal LLWS is expected at KMSS after 11Z and at KSLK towards 22Z.

While fog development cannot be completely ruled out, chances of fog development overnight tonight are lower than last night. Developing southerly flow should prevent formation in all but the most protected valleys, and thus have not included mention of BR or FG in any TAF sites.

Outlook...

Saturday Night: Mainly VFR, with local IFR possible. Definite SHRA. Sunday: MVFR/IFR conditions possible. Chance SHRA. Sunday Night: VFR. Slight chance SHRA, Slight chance SHSN. Monday: VFR. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: VFR. Slight chance SHRA. Tuesday Night: Mainly VFR, with areas MVFR possible. Chance SHRA, Slight chance SHSN. Wednesday: Mainly VFR, with areas MVFR possible. Slight chance SHRA.

BTV WATCHES/WARNINGS/ADVISORIES

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