Marine Weather and Tide Forecast for Barre, VT

KEY MESSAGES
As of 217 PM EDT Monday...

1. Tranquil weather conditions expected through late week, with patchy frost possible nightly through Wednesday night.

2. Little change in latest forecast with mostly dry conditions prevailing into the upcoming weekend with near normal temperatures.

DISCUSSION
As of 217 PM EDT Monday...

KEY MESSAGE 1: Fair, cool, and calm weather will settle in across the region tonight through the the late week. Low-level stratocumulus clouds will linger this afternoon, and eventually become more scattered this evening as strong high pressure begins to take hold from the north. This high will keep any moisture and precipitation chances shunted well south of the area. A seasonably cool and dry air mass will shift south tonight with just a few mid-high clouds.
Fog and frost potential looks fairly low tonight, outside of some of the more sheltered valleys of the Adirondacks and central Vermont due to cloud cover and some subtle flow around 1000ft agl. Cool northerly advected air will keep highs tomorrow in the low to mid 60s, and the higher terrain in the 50s; summit levels around the low to mid 40s. Skies will gradually clear from the west throughout the day tomorrow with some clouds lingering in southern Vermont, associated with a stationary boundary well south of the region. The better frost/fog potential this week will be Tuesday night.
Temperatures have the chance to dip below 40 for the first time this season even in the Champlain Valley. Widespread near freezing temperatures will be possible across the Northeast Kingdom, central Vermont, and the Adirondacks. Pocket mid to upper 20s will be possible with a hard freeze likely in isolated portions of the northern Adirondacks. Frost Advisories will likely be needed tomorrow night for most of the central and northern Vermont, in addition to portions of the northern St. Lawrence Valley. It should be noted that, as of today, these products will no longer be issued for the Adirondacks and Northeast Kingdom, as median date of the first autumn freeze has passed. Thus, the growing season is considered ended in these areas.

Through mid to late week, temperatures will slowly creep up a degree or two each day towards Thursday, with highs in the mid to upper 60s, as the high drifts to the east. Portions of the eastern Greens may see below normal temperatures continue Wednesday with a cold air damming setup. Frost potential will continue Wednesday night, though radiational cooling will be a touch weaker. Fog potential will also be low or non-existent due to a detachment from rainfall by the end of the week.

KEY MESSAGE 2: The primary challenge for the extended forecast is potential for rain showers to impact eastern/southern sections this weekend. Little change has been observed in the 12z guidance, with a large spread in potential solutions associated with potential coastal system. 12z GFS ensemble data shows 0.10 to 0.30" of qpf acrs our central/eastern and southern cwa, while near the International Border stays dry. Latest 12z GFS shows best moisture/lift sliding to our south with mid/upper lvl closed system capturing sfc low pres well off the SNE coast. However, several GFS ensemble members and latest 12z ICON/CMC would have a little precip advecting back into our region. Either way impacts look minimal attm. Initially given very deep dry layer in place with pw values only in the 0.20 to 0.40" range, expect large daily swings in temps with cool nights and mild days. Highs generally in the 60s to near 70 late week into the upcoming weekend with lows upper 20s to lower 40s. However, if more clouds/precip develops this weekend than expected highs will be 4 to 8 degrees cooler, especially associated with north/northeast flow. The prolonged duration of very minimal rainfall could result in expansion of drought conditions across portions of our region as we head into late Sept/early Oct.

AVIATION /18Z MONDAY THROUGH SATURDAY/
Through 18Z Tuesday...Cyclonic northerly flow has resulted in plenty of strato cumulus clouds this aftn with MVFR cigs at BTV/EFK/PBG and RUT with VFR at MPV/SLK and MSS. Expect mostly VFR conditions at all sites by 20z this aftn with north/northeast winds 5 to 10 knots. Overnight aviation challenge is potential for low clouds or fog and associated IFR conditions. Overall setup is not ideal for fog, given 10 to 15 knots near 500 feet, along with some weak cold/dry air advection. Also, HRRR continues to support idea of mid/upper level clouds moving from west to east across our taf sites.
However, it did rain yesterday and sfc dwpts are currently in the mid 40s, so feel cross over values will be reached in several sites. Highest probability of IFR in fog/low cigs will be SLK/MPV and EFK with VCFG at BTV/RUT possible. Any fog/low clouds lifts by 13z with VFR conditions prevailing on Tuesday.

Outlook...

Tuesday Night: VFR. Patchy frost.
Wednesday: VFR. NO SIG WX.
Wednesday Night: VFR. NO SIG WX.
Thursday: VFR. NO SIG WX.
Thursday Night: VFR. NO SIG WX.
Friday: VFR. Slight chance SHRA.
Friday Night: VFR. Slight chance SHRA.
Saturday: VFR. Slight chance SHRA.

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