Marine Weather and Tide Forecast for Vergennes, VT

KEY MESSAGES
As of 245 PM EDT Sunday...

1. Dry and warmer weather expected early this week with increasing chances of showers on Wednesday.

2. Warm and humid weather is expected towards the latter half of next week, with chances for showers and thunderstorms.

DISCUSSION
As of 245 PM EDT Sunday...

KEY MESSAGE 1: Fcst challenge tonight is timing of clearing and potential for fog after midnight. GOES-19 water vapor imagery shows pocket of mid lvl moisture exiting central/southern VT, while deep subsidence is quickly developing near the International Border. As sfc high pres builds into our cwa and drier air aloft mixes toward the sfc, expect clearing skies to develop this evening into the overnight hours. Initially bl winds are in the 5 to 15 knot range with some sounding data showing 15 to 25 knots in the 500 ft to 1000 ft agl, which does not support fog development. However, 1025mb high pres builds directly over SLK by 12z and feel bl should decouple allowing for several hours of shallow dense fog to develop. The highest probability based on winds, recent rainfall, and cross over temps being reached wl be acrs northern NY into parts of central/northern VT, including the NEK and parts of the CT River Valley. Temps wl range from mid/upper 30s SLK to near 50F CPV.

Monday and Tuesday...mid/upper lvl ridge builds directly overhead with sfc high pres slowly sliding off the East Coast. These two days wl feature classic North Country summer-time Chamber of Commerce weather with mostly sunny skies, comfortable humidity values and temps mid 70s to mid 80s. Given deep dry layer in place, expect a large swing between cool overnight lows and mild daytime highs especially Monday night into Tues. Near critically low humidity values are possible on Tues, but winds are mostly light and trrn driven.

For Weds...latest fcst shows mid/upper lvl ridge breaking down as s/w energy in the westerly flow aloft moves acrs our cwa. This energy combined with a warm frnt lifting from sw to ne acrs our cwa, wl produce a period of rain showers. The mid/upper lvl pattern becomes rather messy on Weds aftn with lingering s/w energy acrs our northern cwa and potential for a developing trof. This synoptic scale scenario, combined with pw values climbing btwn 1.25 and 1.50" could support several rounds of showers with increasing humidity values. However, with the clouds/precip, temps may hold in the 70s to near 80F most of the day, especially if warm frnt becomes draped acrs our northern cwa. Plenty of time to fine tune the fcst, but did trend a little wetter and cooler for Weds, given recent trends in our data.

KEY MESSAGE 2: A messy weather pattern is expected for the latter half of next week as southerly flow continues to usher in warm and humid conditions. High temperatures look to climb into the 80s and lower 90s, with dewpoints in the 60s making it feel quite muggy. With such a humid airmass across the region, there look to be daily chances for showers and thunderstorms to end the week, especially across northern New York where instability looks to be the greatest.
Heading into the weekend, there still remains a large amount of uncertainty regarding pattern evolution with model solutions diverging this far out.

AVIATION /00Z MONDAY THROUGH FRIDAY/
Through 00Z Tuesday...Other than some brief MVFR at KSLK/KRUT early in the period, generally anticipate VFR conditions with clearing skies through 06z. Winds will gradually lessen from west to east as high pressure noses into the region, and this will allow for fog development overnight. Highest confidence in fog is at KMSS and KSLK, along with KRUT. There are some signals that fog may briefly move over the KBTV airfield, but have stayed with VCFG for now given the uncertainty. For KMPV and KEFK, winds will be slowest to abate there, so expect if any fog is able to develop, it will be very brief and likely right around sunrise. Otherwise, IFR/LIFR is possible in any fog, with 08z-11z the most likely period to see reductions in visibility and low ceilings. Skies clear from 12z onward with VFR to prevail thereafter. N/NE winds 5-8 kt this evening become light to near calm overnight, then pick back up from the NW after 12z Mon.

Outlook...

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

MARINE
As of 245 PM EDT Sunday...

A Lake Wind Advisory has been issued into this evening for gusty northerly winds at 15 to 25 knots. Given the northerly direction the highest probability of reaching advisory level criteria will be across the central and southern portion of the lake thru sunset this evening. Waves generally 1 to 3 feet with some localized higher seas possible across the open waters.

BTV WATCHES/WARNINGS/ADVISORIES
VT...None.
NY...None.