Marine Weather and Tide Forecast for Marshfield, VT

KEY MESSAGES
As of 307 PM EDT Tuesday...

1. Monitoring the potential for strong to locally severe thunderstorms across Rutland and Windsor counties thru 8 PM this evening.

2. Additional rounds of showers and thunderstorms are expected Wednesday through Friday, as boundary remains draped across our forecast area.

3. Warm and breezy weather for Saturday, then rainy Saturday night through Sunday.

DISCUSSION
As of 307 PM EDT Tuesday...

KEY MESSAGE 1: Radar imagery shows clutter of moderate showers with embedded rumbles moving into the CPV, while Rutland/Windsor counties are in the warm sector with temps well into the mid/upper 70s. A sharp boundary remains draped acrs our cwa this aftn, which is separating temps in the 50s north to mid 70s south, along with favorable llvl convergence and turning of wind profiles. GOES-19 mid lvl water vapor imagery indicates embedded 700-500mb vort approaching the SLV attm, with strong synoptic scale ascent helping with the development of cooler/higher cloud tops. Meso-analysis shows sfc based CAPE values in the 500 to 800 J/kg over Rutland/Windsor Counties, while best 0-1km SRH and 0-3KM SRH values are located just north over central VT, closer to the stronger wind fields and llvl boundary. Given the limited areal coverage of instability and extensive cloud cover, feel the best potential for a strong to severe thunderstorm is over Rutland/Windsor Counties thru 7 PM this evening. Primary threat would be isolated damaging wind gusts, but there still is a non zero threat for a potential weak/isolated tornado acrs the southern CPV thru early this evening.
Pw values are btwn 1.0 to 1.4" range, so localized heavy downpours are likely with rainfall amounts in the 0.25 to 0.75" range, but isolated spots near 1.0.

Tonight, any shower activity should be east of our cwa by 9 PM with strong subsidence inversion developing behind s/w energy. This large area of drying evident on water vapor wl result in plenty of low level stratus clouds overnight with some areas of fog likely, especially in climo favored areas. Even some fog is possible in the CPV, as strong blocked flow develops with light north winds behind rain this evening, which wl act to saturate boundary layer conditions. Lows similar to last night in the mid 40s to mid 50s.

KEY MESSAGE 2: Little change is expected in the large scale synoptic pattern acrs the Great Lakes into the NE CONUS for Weds thru Friday, as westerly flow aloft with embedded s/w's continue to impact our fa. Mid/upper lvl ridge prevails over the SE CONUS, while trof is lingering over central-eastern Canada, helping to enhance fast 700- 500mb flow acrs our cwa. Given limited amplification, expect stationary boundary to remained draped acrs our cwa, supporting warmest temps over Rutland/Windsor Counties and coolest near the International Border. Always challenging to determine amount of cloud cover/instability in the pattern, as soundings show plenty of llvl moisture below 850mb lingering on Weds and again on Thurs for most of the day. Greatest potential for a few embedded rumbles of thunder wl be Essex County, NY into central/southern VT each aftn.
The latest trends have better probability of sfc based CAPE values >500 J/kg mostly south of our cwa on Weds, as deep layer moisture prevails acrs our cwa. Temps mainly in the mid 50s MSS to mid 70s VSF, but this could be high, as outflow from this evenings convection and clouds could produce cooler temps in the CT River Valley on Weds. Little change in temps are expected on Thurs as another embedded s/w and weak 1004mb low pres tracks along llvl thermal boundary to produce more showers and embedded thunderstorms.
If more sun develops than anticipated temps could be well into the 70s on Thurs, especially given progged 925mb temps in the 12-17C range. Pw values in the 1.0 to 1.30" does support localized heavy downpours are possible, both Weds and Thurs afternoon, and given multiple rounds of precip, combined with some additional high elevation snowmelt, some sharp rises on central/northern waterways are likely thru Friday. No flooding is expected, but high flows wl need to be watched.

KEY MESSAGE 3: The weather pattern remains active going into the weekend, but any threat for hazardous conditions remains low. The next system to impact our area will take the form of a strengthening surface low lifting northeastward through southeastern Canada. Ahead of the low, temperatures will be warmer than normal for Saturday amid the increasing southerly flow, especially over our western counties. High temps will be in the mid 60s to low 70s, with breezy south winds increasing through the day. The best window for increased south winds will occur late Saturday into Saturday night, before the steady rain begins. The south/southwest orientation of the low-level jet will favor gusty winds over the Saint Lawrence Valley, off the northern slopes of the Adirondacks, and channelled up the northern Champlain Valley, where gusts in the range of 20 to 30+ knots are possible...locally higher over the Saint Lawrence Valley.

The cold front will move through from west to east Saturday night into Sunday, bringing a widespread soaking rainfall. The timing of the frontal passage will limit destabilization, thus limiting in turn thunderstorm potential. National Blend of Models thunderstorm probabilities cap out on Sunday under 10%. While our QPF forecast does not extend through Sunday, probabilistic data points to the most likely QPF range from Saturday night through Sunday between 0.25 and 0.5 inch, which would not create widespread hydro concerns.
A look at the MMEFS ensemble river forecasts for the longer range show rises in rivers towards the end of the week into the weekend, but these rises remain well within banks. Given the multiple chances for rain coming up, we will continue to keep a close eye on rivers but no issues are currently anticipated.

AVIATION /19Z TUESDAY THROUGH SUNDAY/
Through 18Z Wednesday...Showers with embedded thunderstorms will continue to move through the forecast area this afternoon into this evening. The highest instability remains over our southern counties, so have limited mention of thunderstorms to just the KRUT and KSLK TAFs, where confidence is the highest. Thunderstorm threat will be highest through 21Z at KRUT, and through 20Z at KSLK, afterwhich showers will continue but thunderstorm threat diminishes.
Showers will generally come to an end between 22Z and 04Z, followed by lowering ceilings through the remainder of the night as low-level moisture is trapped under a inversion. This will lead to widespread IFR ceilings between 08Z and 14Z, with some areas of LIFR ceilings possible. Visibilities may also lower with some mist around, but confidence is lower on reduced visibilities than reduced ceilings.
Nevertheless, cannot alltogether rule out some visibilities below 1SM, especially between 09Z and 12Z at KSLK and/or KMPV. Winds will be quite variable across the forecast area with a slow moving frontal boundary draped overhead. Most TAF sites will see winds initially start from the south around 5-10 knots, becoming southwest/west toward 00Z, and then light and variable towards 12Z.
Some gusts 15 to 20 knots are expected through 00Z. One exception will be KMSS, where lightnortheast/north winds will prevail the entire TAF period. Another exception will be the northern Champlain Valley including KBTV and KPBG, which are starting off with winds from the northwest and northeast respectively, but will both see winds trend light and variable after 00Z.

Outlook...

Wednesday Night: Mainly MVFR, with local IFR possible. Chance SHRA, Slight chance TSRA.
Thursday: Mainly MVFR, with local IFR possible. Likely SHRA, Slight chance TSRA.
Thursday Night: Mainly MVFR, with local IFR possible. Chance SHRA.
Friday: Mainly MVFR, with local IFR possible. Chance SHRA.
Friday Night: Mainly VFR, with local MVFR possible. Slight chance SHRA.
Saturday: MVFR. Slight chance SHRA.
Saturday Night: Mainly MVFR, with local VFR possible. Chance SHRA.
Sunday: MVFR/IFR conditions possible. Likely SHRA.

CLIMATE
As of 344 AM EDT Tuesday...

Incoming warmer air is presently forecast to approach daily record values. The most likely dates for near or broken records will be today with mild overnight air leading to high minimum temperatures. Below are some of the daily records in jeopardy of being broken (current forecast at or within 3 degrees of the record).

Record High Minimum Temperatures:

April 14: KBTV: 54/2023 KPBG: 51/1964 KSLK: 47/1964

EQUIPMENT
The Colchester Reef meteorological station is out of service.
This site is not serviced by the NWS. An estimated return to service is May 1st. Please contact us if you observe winds significantly deviating from the recreational forecast.

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