Marine Weather and Tide Forecast for Canaan, CT

KEY MESSAGES
1) Isolated to scattered showers, with isolated thunderstorms, are expected Wednesday afternoon into Thursday, as a cold front slowly moves southward across the region.

2) Unsettled weather returns over the weekend, as a broad upper level trough impacts the region, although there is low confidence in the timing, rainfall amounts and details with this system.

DISCUSSION
KEY MESSAGE 1...

High pressure builds in briefly tonight into early Wednesday with patchy to localized areas of radiational mist or fog occurring across the region, especially in the sheltered valleys, as temps fall off into the 50s to around 60F with a few upper 40s over the southwest Adirondacks. The mist or fog burns off quickly with mid and high clouds increasing ahead of a pre-frontal sfc trough and a cold front approaching from the Great Lakes Region and southeast Canada. The best chance of showers and isolated thunderstorms will be west/northwest of the Greater Capital Region. The latest HRRRs indicates mean SBCAPE of 250-750 J/kg with 0-6 km shear 30-40 KT. Some of the CAMs like the 3-km NAM have SBCAPEs around 1000 J/kg or so with higher dewpts. The instability being limited showed keep updrafts from being tall enough for any severe threat. Some gusty winds may occur with a few storms...and the showers weaken, as they move towards the Capital District and Hudson Valley by nightfall. Max temps rise into the lower to mid 80s in the valleys and upper to 70s over the hills and mtns.

The pre-frontal trough moves through at night with the showers weakening, as they move eastward with limited upper level support and moisture convergence. The cold front will be moving across the southern half of the forecast area in the late morning through the afternoon. Some patchy fog may occur especially north and west of the Albany in the morning. The latest NBM had very little PoPs north of the mid-Hudson Valley.
We collaborated with WFOs GYX/BTV/BOX and expanded the slight chance of showers to southern VT, the southeast Capital Region and Berkshires and points south. If the front is faster, then the showers and isolated thunderstorms will be south of the Mass Pike and closer to I-84. Once again, instability looks limited with SBCAPEs mainly 750 J/kg or less near I-84 in southern Dutchess and Litchfield Counties, so thunderstorms are expected to be non-severe. High pressure builds in Thu night thru Friday with cooler and drier weather.

KEY MESSAGE 2...

The next chance of a widespread rainfall looks to be late Saturday into Sunday. Mid and upper-level height falls occur over the Great Lakes Region, southeast Canada into the Northeast, as a deep upper trough develops based on the medium range deterministic, AI and ensemble guidance. A series of short-waves dig into the trough, as it amplifies and may close off somewhere near NY and New England Sun into Mon. It may be as far poleward as near James Bay. A southern stream disturbance or sfc low may form near the Mid Atlantic Coast with the developing upper-level trough Sat night into Sunday bringing periods of rainfall with a few thunderstorms. The latest 13Z/NBM indicates the probabilities >0.50" of rainfall for the 24-hr period ending 8 pm Sunday are 40-70% across eastern NY and western New England. The probs for >1.00" of rainfall are only 20-40%. The placement of the closed low and the amount of QPF are still somewhat uncertain, but some locally heavy rainfall may occur Sun-Mon. We will continue to monitor guidance trends throughout the week. Temps trend cooler than normal for the 2nd half of the weekend into early next week. A break in the pcpn may occur Mon night into Tue, as the upper low moves down stream.

AVIATION /19Z TUESDAY THROUGH SUNDAY/
Through 18Z Wednesday...VFR conditions will prevail for the majority of this TAF period across all terminals, with variable to light northwesterly winds persisting throughout this afternoon. The consistent MVFR cigs across the region this morning has finally begun to burn off, with some lingering low- to-mid level clouds expected to stick around through this evening. Winds will gradually weaken and become calm after 00Z, which will persist throughout the overnight hours at all terminals. Given the calm winds and mostly clear skies, there is potential for the development of radiational mist/fog after 06Z. There is higher confidence for this to occur at KGFL and KPSF, which could see brief drops to IFR vis, while there is lower confidence for KALB and KPOU, reflected by TEMPO groups with brief drops to MVFR vis. Any mist/fog that does develop should burn off by 12Z Wednesday, leaving VFR conditions and light southerly to southwesterly winds through the rest of the TAF period.

Outlook...

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

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