Marine Weather and Tide Forecast for Wilmington, VT

KEY MESSAGES
1) Above normal temperatures and increasing humidity levels are expected through Friday. Heat Index values may be high enough to allow for an increased risk in heat related illnesses on Thursday and Friday.

2) There is a chance for thunderstorms each day Wednesday through Friday, mainly in the afternoon and evening hours. Some storms could be severe with damaging winds, especially on Friday. Storms may be capable of producing heavy downpours as well.

DISCUSSION
KEY MESSAGE 1...

A warm and humid air mass will be building over the region for the next few days, as surface high pressure shifts eastward and a low level southerly flow will remain in place over the area.
850 hpa temps will be warming to +16 to +19 C across the entire region ahead of an approaching storm system.

With a warm front moving through the area, there will be some clouds, showers and possible thunderstorms on Wednesday. This may limit daytime heating slightly for Wednesday, but valley areas should still reach into the lower 80s. With dewpoints rising through the 60s, this should still keep heat index values in the lower to middle 80s for valley areas.

Even warmer temps are expected for Thursday and Friday, with a partly to mostly sunny sky both days, despite some late day convection once again. Highs will be in the upper 80s to near 90 on Thursday and probably in the lower 90s for Friday. With dewpoints nearing 70 degrees in valley areas, heat index values will be in the 90s both days. Heat index values may reach advisory criteria in the mid Hudson Valley for Thursday and many valley areas for Friday. These values will allow for an increased risk for heat related illnesses each day.

Somewhat cooler and less humid conditions are expected behind a cold front for the weekend, so this will lower the threat for heat-related illnesses by Saturday.

KEY MESSAGE 2...

There will be the potential for convection each day, beginning Wednesday through Friday. While there could be a threat for severe storms each day, the most widespread threat will probably be on Friday due to better forcing over the region.

On Wednesday, an upper level disturbance and surface warm front will be moving across the area. Widespread clouds are expected through the day, which may limit surface heating and overall instability. There will be some passing showers and rumble of thunder around midday before another round of convection for the afternoon and evening. These earlier showers and clouds may keep lapse rates on the low side as well (under 6 deg C/km).
The overall forcing aloft is rather weak and 0-6 km bulk shear values are generally in the 20-25 kt range. 12z SPC HRRR shows the best updraft helicity just southwest of the area, but it is fairly close. Overall, the severe threat is fairly low for Wednesday, with a better threat off to the west of the area. SPC has the marginal risk scrapping into our western areas. While an isolated storm late in the day may have damaging wind gusts, the overall threat is fairly low for Wednesday. With the rising PWATs, locally heavy downpours may be a concern.

For Thursday, forcing still remain low, but there should be better instability compared to Wednesday due to more sun and higher heating. The main forcing is still far off to the west, so overall coverage of storms looks on the lower side and shear is still fairly low. Still, if storms can get going, there may be a threat for isolated damaging winds. There remains a marginal risk once again for severe storms, but the higher threat will again be west of the area.

Higher coverage of thunderstorms looks to occur for Friday, for the afternoon into the evening, as the main upper level forcing gets closer and a surface cold front approaches from the west.
There may be an organized line of thunderstorms for late in the day. Lapse rates aloft for Friday look a little more impressive compared to Wed/Thurs. SPC has a Day 4 outlook with a 15% contour (SLIGHT risk equivalent) over our area due to the decent lapse rates and moist dewpoints in place. Will continue to monitor model trends, as the timing of the boundary will determine the overall severe risk for Friday.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/
Through 00Z/Thursday, VFR conditions are expected overnight into Wednesday morning, although some passing showers around or shortly after daybreak could bring brief MVFR conditions (Cigs/Vsbys) to KGFL and KALB. A break in the showers may occur during the midday hours, before additional showers and possible embedded thunderstorms develop from west to east during Wednesday afternoon. The greatest areal coverage of showers/thunderstorms is expected to be at KGFL and KALB.
Periods of MVFR/IFR Vsbys/Cigs will be possible within any heavier downpours that occur.

Light/variable winds overnight except south at 5-10 KT at KALB, will become south to southeast at all sites by late Wednesday morning through the afternoon. Winds will be stronger, and variable in direction in/near any thunderstorms.

Outlook...

Wednesday Night: High Operational Impact
Likely SHRA
TSRA.
Thursday: High Operational Impact
Chance of SHRA
TSRA.
Thursday Night: Moderate Operational Impact
Slight Chance of SHRA
TSRA.
Friday: Moderate Operational Impact
Likely SHRA
TSRA.
Friday Night: High Operational Impact
Likely SHRA
TSRA.
Saturday: Low Operational Impact. Breezy. NO SIG WX.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: Low Operational Impact
Slight Chance of SHRA
TSRA.

ALY WATCHES/WARNINGS/ADVISORIES
CT...None.
NY...None.
MA...None.
VT...None.