Marine Weather and Tide Forecast for Cape Vincent, NY

KEY MESSAGES
1) Rainfall continues today across western NY with the remnants of post tropical cyclone Isaias.

2) The next round of rain showers arrives late Monday night with strong thunderstorms possible across western NY Tuesday.

DISCUSSION

KEY MESSAGE 1...Rainfall continues today across western NY with the remnants of post tropical cyclone Isaias.

Latest satellite imagery shows a large scale upper low across eastern KY drifting east with the remnants of Isaias. Ahead of the low, deep southerly moisture transport has led to extensive cloud cover and rain for much of the eastern seaboard. Heaviest precipitation early this afternoon has been placed across central and eastern PA while much of western NY remains just outside the area of best synoptic scale forcing. Widespread, stronger returns as noted by regional radars will begin shifting across the NY/PA border this afternoon. NBM probability of exceeding 0.25" of rainfall maximizes from the Southern Tier into the Finger Lakes region through the remainder of the Sunday. Rainfall will taper off from west to east overnight into early Monday morning as the upper level disturbance shifts east across the Mid-Atlantic and a ridge of high pressure builds up from the south.

For far western NY, including the Niagara Frontier, minimal rainfall has been reported as of midday Sunday. This was being hinted at with the eastward shifts in model guidance over the past 24-36 hours for the main precipitation shield. However, a deformation band developing over southwestern Ontario will begin to shift eastward later this afternoon and provide another chance precipitation with this system, though accumulations will likely max out near a tenth of an inch.

KEY MESSAGE 2...The next round of rain showers arrives late Monday night with strong thunderstorms possible across western NY Tuesday.

The next low pressure system will pass east across the Great Lakes late Monday and into Tuesday, pushing a cold front southeast across the region Tuesday evening. Ahead of the front and aligned with a leading shortwave, expect another round of rain showers Tuesday from the Niagara Frontier east towards the North Country. A few thunderstorms can't be ruled out as mid-level lapse rates approach 7 C/km with the presence of an EML and effective shear of 35-40 kt thanks to a 50 kt jet at 700mb.

While there still remains quite a bit of uncertainty with high temperatures across the region Tuesday, latest ensemble trends have shifted the track of the low slightly farther north. This will allow portions of western NY to remain under better warm southwesterly flow as 850mb temps climb around 14-16 degC, near the climatological 99th percentile for mid-October. This could support temperatures 10 degF above normal, especially across the Southern Tier. NBM shows Tuesday afternoon highs for locations north of I-90 with considerable spread still mainly tied to the timing of precipitation, cloud cover, and the frontal passage.

This being said, storms will likely remain elevated due to poor low- level lapse rates, but additional shifts in the low track could provide more limited cloud cover improving boundary layer destabilization and potential for afternoon thunderstorm development over western NY. SPC has highlighted western NY with a Day 3 Marginal Risk for severe storms.

AVIATION /18Z SUNDAY THROUGH FRIDAY/
MVFR/IFR CIGs spreading into the western Southern Tier early this afternoon. This deteriorating trend will continue to gradually work north across the TAF region through this evening. Most of the rain activity associated with post tropical cyclone Isaias will remain southeast of the region, as the remnant low moves to Delmarva through tonight. Any shower activity on the northwest shield of the system will likely only reduce VSBYs at times to 5-6SM. The risk for any showers should end by 06Z, but MVFR/IFR CIGs will likely hold through Monday morning, with gradual improvement from west to east Monday afternoon.

Outlook...

Monday Night and Tuesday.. MVFR/VFR with rain showers possible.

Wednesday and Thursday...Mainly VFR.

Friday...Restrictions likely in rain showers.

MARINE
Rain showers are expected to continue through much of the day today before moving off to the east headed into Monday morning. Winds will be variable Monday morning before turning southwesterly Monday night into Tuesday across the lower Great Lakes ahead of the next cold frontal passage. Rain showers expected Tuesday and southwest winds 10-20 kt will turn northwesterly Tuesday night behind the front.
Waves will be 3 to 6 feet Tuesday which may bring another round of Small Craft Advisory conditions. High pressure will build over the Great Lakes for mid-week veering winds to out of the north by Thursday.

BUF WATCHES/WARNINGS/ADVISORIES
NY...None.
MARINE...None.