Marine Weather and Tide Forecast for Ludlow, VT

NEAR TERM /THROUGH SATURDAY NIGHT/
As of 712 PM EDT Friday...No big changes for the first update this evening. Have adjusted forecast to reflect current radar trends. Some scattered light rain showers have moved across the area. Winds are light. Previous discussion follows.

A dynamic, intensifying low pressure system will move over the eastern Great Lakes tonight and pass right across northern New York and northern Vermont during the day. As such, quite a bit of variety in weather is expected including periods of rain, isolated to scattered thunderstorms, and much cooler conditions tomorrow night.

For tonight, showers with embedded thunder across central New York associated with a mesoscale low pressure area will move across western portions of northern New York roughly between 6 and 11 PM. Based on marginal instability and modeled forecast soundings, have left thunderstorms out of the forecast but a non-zero chance of lightning exists. Otherwise, the ongoing light rain showers in portions of our region will continue to lift to the north this evening. The main area of widespread rain expected during the first half of the weekend is on track to arrive largely between 1 AM and 3 AM and persist through much of the morning, tapering off from west to east between 8 AM and noon. A soaking rain of 0.5" to 1" is expected, with the higher amounts favored in southern portions of Essex County, New York into central and eastern portions of Vermont, especially in upslope favored areas with a shallow and moist southeasterly wind direction.

Following this rain, attention turns to the instability that can develop during the midday hours ahead of the surface cold front. The timing of the front suggests this potential is mainly in Vermont/eastern Adirondacks as colder and stable air will be making its way into New York quickly as winds turn southwesterly/westerly. Given the strength of the front and progged 700 millibar moisture, if there is sufficient heating showers become widespread ahead of the boundary. The NAM3/HRRR show a similar axis of instability with marginal surface-based values in the 500 - 1000 J/kg, supportive of at least chances of thunderstorms. There is limited potential for strong gusts associated with any linear features that can develop, given effective shear of near 30 knots. Moist profiles with limited CAPE suggest brief downpours and gusty, but not strong, gusts is most likely.

Moving into Saturday night, sub-freezing 850 millibar temperatures will settle into the region with mountain summits above 3000 feet seeing rain showers change to snow overnight.
Steady precipitation will wrap around the departing surface low pressure system, such that northern New York will see the bulk of the light rain/snow overnight. Following highs in the 60s on Saturday, lows Saturday night look to slip into the 30s to low 40s.

SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/
As of 312 PM EDT Friday...Sunday appears likely to be cold and dreary. The 540dam 1000-500mb thickness line will cross east as a compact upper low tracks overhead and to our east. Deep moisture will wrap around the western side of surface low pressure moving along the Maine Coast. Elevation dependent rain and snow will move north to south over the area with breezy and cool weather anticipated. Temperatures will linger in the mid 40s to lower 50s from the Adirondacks eastwards. The low will shift far enough east for the St. Lawrence Valley to still push 60 with partial clearing. Lower valleys will be breezy and rainy. Higher elevations should stay in the 30s and experience sloppy, wet snow. This weather feature will at least be progressive enough to shift east by nighttime. Steady north winds will result in a cool Monday morning in the 30s to near 40.

LONG TERM /MONDAY THROUGH FRIDAY/
As of 312 PM EDT Friday...As has been the general pattern, we'll have high pressure set up for a couple days. Warm advection takes over pretty fast, and so we warm right up into the 60s to near 70 on Monday. On Tuesday, the previous upper low will have stalled across the Canadian Maritimes. With that and the ridge cresting overhead, there should be plenty of dry, subsident air across the region. Initially, there could be some gusty winds combined with RHs around 30-35 percent, but with the quickness of incoming precipitation and steady intervals of rain over the last month, not anticipating this to be of much concern. Temperatures will reach well into the 70s Tuesday afternoon. Moisture will increase ahead of a prefrontal trough that will slide east during the afternoon. Ensemble guidance indicates probability of SBCAPE greater than 300 J/kg highest over the St. Lawrence Valley around a 30% chance. This is mainly from the timing being close to sunset across Vermont beyond the best diurnal heating. The EPS MUCAPE percentages are running closer to 100%, which makes sense given the better resolution.
Assessing the probability that these values align with at least 30 knots of shear, the EPS also indicates a 60% chance of their collocation. The Storm Prediction Center has already highlighted the potential for the St. Lawrence Valley. With such a dynamic 995 mb surface low passing south of James Bay and 70s coupled with upper 50s dewpoints across that region, this seems like a real possibility. As the prefrontal trough slides east Tuesday evening, the loss of instability will cause a weakening trend as precipitation slides across Vermont overnight.

Post-frontal gusts will lead people to believe we might be in for another cold day. Surface high pressure is going to be rather quick to come back, though. Skies should trend clear, winds will subside shortly after noon, and then temperatures will make their way into the 60s. After a couple dry days, another dynamic weather system appears poised for Friday evening.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/
Through 00Z Sunday...A dynamic, intensifying low pressure system will move over the eastern Great Lakes tonight and pass right across northern New York and northern Vermont during the day tomorrow. We can expect periodic showers for much of the next 24 hours, though they become organized into two more distinct waves, one arriving overnight tonight and the next tomorrow afternoon. Visibilities are not expected to be overall low, with blanket 4+ miles vis for most sites in the TAF, however, it is not out of the question for occasional and unpredictable heavier showers lowering vis further at times in any more potent showers or thunderstorms. Ceilings will also decrease with these showers, lowering to 3000 feet above ground level or below by about 10Z-14Z Saturday and remaining low for the remainder of the TAF period (through 00Z Sunday). Ceilings could fall even lower below 1000 feet at several sites, perhaps all, but highest confidence is for SLK, MPV, RUT, and MSS as the Champlain Valley will likely scour out low clouds the fastest tomorrow (BTV and PBG). Highest confidence for timing of these IFR ceilings will be 12Z-16Z onward. Winds will be out of the south or southeast for much of the night tonight, turning more westerly to northwesterly tomorrow. LLWS concern will be brief, around 10Z-15Z, for BTV, SLK, MPV, EFK, and RUT.

Outlook...

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

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