textproduct: Burlington

WHAT HAS CHANGED

As of 220 PM EDT Wednesday...

No significant changes were made to the forecast.

KEY MESSAGES

As of 220 PM EDT Wednesday...

1. Trending seasonably cool and showery towards the end of the week.

2. Cold and wet conditions will be the start to the weekend.

3. Generally unsettled with chances for showers most days in the long term, but no hazardous weather expected.

DISCUSSION

As of 220 PM EDT Wednesday...

KEY MESSAGE 1: A moisture starved cold front is shifting south through the region this afternoon evident on current satellite with associated fair weather cumulus streaks. Mid to upper level dry air from the southwest will limit any shower activity this afternoon. An isolated shower cannot be completely ruled out tonight, mainly across the Northeast Kingdom and near the International Border, however, a lack of true convergence, weak forcing, and entrenched mid level dry air will cause any shower initiation to struggle. Temperatures will trend cooler behind the front with seasonably cool overnight lows in the upper 40s to low to mid 50s tonight. Winds will shift to the north tomorrow with cooler air remaining in place as highs will be in the 60s. Cooling aloft with some diurnal surface heating may lead to some weak instability capable of producing some isolated to scattered showers Thursday. Showers will be more confined to the higher terrain of the Adirondacks and more so the northern Green Mountains and Northeast Kingdom, with only light accumulations expected under any isolated showers. North winds will keep Thursday night into Friday on the cool side with temperatures in the upper 50s to low 60s ahead of our next system late Friday.

KEY MESSAGE 2: A deep upper low will become blocked across the Canadian Maritimes Friday with low 500mb height anomalies will be overhead Saturday. Notably, this closed low originates well north of the Hudson Bay with temperatures resembling that of early to mid spring or mid to late fall, rather than the end of May/early June. 850mb and 925mb temperatures will be in the 10th percentile with near freezing and 6C temperatures, respectively. Highs Friday and Saturday around 10 to 15 degrees below normal as a result, with values in the low to mid 60s, and lows in the low to mid 40s. Overnight lows may be slightly warmer across the St. Lawrence and Champlain Valleys due to water temperatures helping to moderate air temperatures.

These lower temperatures will be accompanied by scattered to widespread instability driven shower and rain activity late Friday into Saturday. A surface low looks to pass over the Champlain Valley with overrunning precipitation focused over central and northeastern Vermont. Rainfall amounts between a quarter of an inch in the Champlain Valley to half an inch to an inch across the Northeast Kingdom are possible. Lesser amounts are expected in northern New York with up to tenth or two of rain, closer to the International Border and Lake Champlain. The GFS denotes the 540 thickness line will be over the Adirondacks which is uncommon, but not unheard of for this time of year. As a result, with snow levels falling to around 4000ft AGL, there is a chance for a dusting of wet snow atop the summits of the High Peaks of the Adirondacks late Friday night into early Saturday morning. Friday night into Saturday unfortunately looks to be raw with the cooling temperatures, rain, and some breezy conditions to 10 to 15 mph winds. Beyond Saturday morning, shower activity coverage will decrease from west to east, with some isolated lingering showers possible near the Connecticut River with continued cyclonic flow.

KEY MESSAGE 3: Looking into the longer term, our weather pattern will remain unsettled. Broad cyclonic flow will dominate...kept in place by a larger scale blocking pattern over the CONUS. As is typical in these setups, the longer term evolution of the omega block...and the timing of the eventual pattern shift out of the block...is notoriously difficult to pinpoint this far out. This is highlighted by increasing model spread over the northeastern US amongst ensemble solutions. What is more certain however, will be that general troughiness will dominate at least through early next week, resulting in chances for showers with some embedded thunderstorms each day. Temperatures will remain slightly below normal to finish out the weekend, but a warming trend will bring temps to near normal by midweek as the ridge slowly builds eastward.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

Through 18Z Thursday...We are starting off the TAF period with partly to mostly sunny skies and widespread VFR conditions. However, cloud cover will increase and bases gradually lower through the night as a secondary cold front drops southward from the north. Some isolated showers are possible tonight, mainly along the International Border between 00Z and 06Z, though have left mention out of TAFs due to low chances. Visibilities are expected to remain at VFR levels, even within any showers that may pass through. Ceilings will briefly lower toward high MVFR levels between 10Z and 14Z, then lift back up to VFR toward the end of the 24 hour TAF period. Winds will be from the northwest between 6 and 12 knots this evening, and then diminish to under 6 knots overnight.

Outlook...

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

BTV WATCHES/WARNINGS/ADVISORIES

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