textproduct: Burlington

WHAT HAS CHANGED

As of 304 PM EDT Tuesday...

No significant changes were made with this forecast package.

KEY MESSAGES

As of 304 PM EDT Tuesday...

1. Patchy drizzle overnight gives way to more widespread showers later Wednesday into Thursday. Some embedded rumbles of thunder will be possible, along with gusty winds and locally heavy rainfall.

2. Scattered showers expected to end the work week.

3. A few showers may linger into Saturday, then dry weather is likely into early next week.

DISCUSSION

As of 304 PM EDT Tuesday...

KEY MESSAGE 1: This morning's showers, which brought upwards of a third of a inch of rain to our southern and western areas, have pushed to our south this afternoon. This activity was associated with a wave of low pressure riding along a nearly stationary frontal boundary, which stretches from roughly the eastern end of Lake Ontario, through central NY and down into southern New England. While drier air, evident on satellite imagery, is spreading in at mid-levels, low-level moisture will remain fairly abundant this evening and overnight, especially along the southern/eastern slopes of the Adirondacks and in eastern VT, where southeast flow will allow moisture to settle under the inversion. In these areas, expect there will be patchy drizzle and perhaps periods of light rain. Otherwise, tonight will be dry with lows in the 50s to near 60F.

More widespread precipitation is expected Wednesday and Wednesday night as another system rides along the aforementioned stationary front. This system will be more dynamic than the one that moved through this morning, with a surface low to trek along the St Lawrence Valley into southern Quebec. Shear will be ample given a potent 40-50 kt 850 mb jet ahead of the low, resulting in 0-6km shear values of 30-40 kt. The main question will be instability, which will likely be limited by extensive cloud cover early in the day. However, some clearing will be possible during the afternoon, particularly in northern NY, with MU CAPE values of 500-1000 J/kg. While some pop-up showers/thunderstorms can't be totally ruled out in the afternoon, expect the bulk of any activity to hold off until late afternoon/early evening, approaching the St Lawrence Valley around sunset or so. There could be enough lingering daytime instability to allow for more robust thunderstorms to develop, including the potential for small scale bowing features. Strong winds would be the biggest threat, restricted to just areas west of the Adirondacks, where the latest Day 2 Severe Weather Outlook continues to indicate a Marginal Risk (Level 1 out of 5) for strong/severe thunderstorms.

All that said, overall expect embedded thunderstorms within a broad swath of moderate rain to spread from west to east Wednesday evening and Wednesday night. Rainfall could be heavy at times, with the HREF indicating localized 3-hr amounts of 1-2 inches overnight. Since much of our region missed out on significant rainfall today, don't anticipate any widespread flooding issues, but ponding of water in poor drainage areas will be possible. Gusty south winds will be possible regardless, especially here in the Champlain Valley where channeling will allow gusts up to 30 mph, locally higher over Lake Champlain into the Islands. Elsewhere, expect gusts mainly 25 mph or less overnight into Thursday.

Showers quickly exit to the southeast by mid-morning Thursday, followed by drier air and subsidence. Scattered showers with a few thunderstorms will develop during the afternoon as a weak surface trough/frontal boundary crosses from northwest to southeast. However, expect most areas will only see a brief shower with perhaps some rumbles of thunder at worst.

KEY MESSAGE 2: Any lingering showers will end Thursday night with the loss of daytime heating and an influx of drier air spilling into the region from the north. However, we expect showers to redevelop again Friday afternoon as the upper trough starts to swing southward across eastern Quebec and into northern Maine. Showers will be focused over the northern high terrain, especially in northern Vermont, closest to the incoming trough. Otherwise, partly to mostly cloudy skies are expected. Highs will be seasonable, generally in the 70s, with northwest winds a little on the breezy side.

KEY MESSAGE 3: The upper-level low centered over central Quebec will shift southeastward Friday night and Saturday. Multiple shortwaves rotating around the low will keep some scattered showers around, interspersed with drier periods in between shortwaves. On Saturday, flow will become northeasterly and thus favor showers on the northeastern slopes. Sunday looks drier as the low moves out to sea and high pressure builds in from the west. Given the lingering upper- level low, temperatures will remain near to cooler than seasonal normals. Highs throughout the weekend will generally be in the upper 60s to mid 70s, with lows in the 40s and 50s. Beyond the weekend, deterministic models diverge in their solutions.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

Through 00Z Thursday...Most terminals are currently VFR with some periodic reductions of ceilings into the MVFR range at SLK and RUT. Ceilings will lower as the night goes on and they will fall to a mix of MVFR and VFR, with some intervals of IFR possible at MPV. While not expected, if the skies manage to clear out at SLK, fog formation would be possible there later in the night. Ceilings will increase tomorrow morning and they should all be VFR by mid-morning. Winds will mostly be southerly/southeasterly tonight and under 10 KT. Winds will increase significantly during the day tomorrow, with southerly gusts in the 15-25 KT range for most areas, with gusts up to 30 KT possible in the Champlain Valley. Scattered showers and thunderstorms will develop late tomorrow afternoon and continue into the evening. The highest probabilities of thunder and reduced visibility will be at SLK and MSS.

Outlook...

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

BTV WATCHES/WARNINGS/ADVISORIES

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