Marine Weather and Tide Forecast for Lewiston, NY

KEY MESSAGES
1) Abnormally strong surface low will bring gusty winds, showers and thunderstorms today and tonight.

DISCUSSION
KEY MESSAGE 1...Abnormally strong surface low will bring gusty winds, showers and thunderstorms today and tonight.

A strong surface low will track across the central Great Lakes this morning and into southern Ontario and Quebec through this morning where it will stall and remain in place through Friday.

Showers with embedded thunderstorms are found across the forecast area early this morning as a warm front and LLJ push into the region. With increased moisture over the region and the potent LLJ, heavy downpours are expected at times. Additional showers are expected as a shortwave trough crosses the area this morning ahead of the systems cold front.

The cold front associated with the system will track through the area from mid morning to early afternoon hours. Showers with embedded thunderstorms will become more scattered behind the passing front, but with the larger trough overhead, combined with surface convergence at times associated with lake breeze boundaries, more organized showers will be possible at times in these favorable areas. This passing trough will help continue the potential for at least some showers and embedded thunderstorms. Rainfall amounts across western and north central NY still expected in the range of 0.25-0.75" with locally higher amounts within thunderstorms.

Winds have already started to increase ahead of the strong sfc low out of the southeast for the favorable downslope areas of the Chautauqua Ridge. Downslope winds will continue to expand east this morning ahead of the sfc low, including for the Tug Hill and northwestern portion of the Finger Lakes. As the sfc low tracks northeast, winds will shift to the south and then the southwest.
Wind gusts for downslope areas will reach the 45 to 55 mph range with the strongest winds expected for the Chautauqua Ridge. As winds shift to the southwest, winds will increase across the entire area, especially over the higher terrain and northeast of both Lake Erie & Ontario. Wind gusts across much of the area up to 50 mph will be possible for most areas, with gusts approaching 55 mph at times for areas northeast of the lakes. Winds are associated with a tight pressure gradient over the region associated with the strong sfc low and a strong LLJ of up to 65-75 kts. Winds will be slow to diminish later this evening into Friday as the sfc low lingers over Central and Southern Quebec through Friday, slowly weakening in the process.
This will prolong gusty winds into the day on Friday, but winds are not expected to be nearly as strong as they will be today. Most of the forecast area has been upgraded to a High Wind Warning, with a handful of counties remaining with the Wind Advisory. Wind related advisories and warnings are in effect through 8PM this evening. While winds aren't expected to be abnormally strong compared to a winter type setup, the bigger concern is the amount of leaves on the trees with wind gusts of 50 to 55 mph, with the leaves increasing drag from the wind vs in the cool season when trees are bare.

There is the potential for thunderstorms today, however cloud cover should limit the amount of instability and overall thunderstorms.
Strong wind fields though today will be supportive of a high shear low cape type scenario, so any storms that do develop will have the potential to bring gusty winds in addition to what is already expected. Areas from the Genesee Valley eastward are in a level 1/5 'Marginal Risk' and far eastern Lewis County is in a level 2/5, 'Slight Risk' of severe thunderstorms. Storms that develop within the moist warm sector will have a better chance for heavier downpours as well.

AVIATION /07Z THURSDAY THROUGH MONDAY/
An anomalously strong area of low pressure (by mid-June standards), will bring multiple rounds of showers and thunderstorms, along with a prolonged period of strong non-convective winds today.

Warm front currently pushing through the region with areas of light to moderate showers producing MVFR VSBYs in the heavier showers.
CIGS remain VFR to start the TAF period, however expect MVFR CIGS to develop through the early morning hours across western NY, while mainly low VFR CIGS expected to develop from the Genesee Valley/Finger Lakes region to the eastern Lake Ontario region. South to southwest winds will ramp up through the early morning hours with 25-35 knot gusts becoming common by daybreak.

Warm front exits northeast of the area, but will be quickly followed by a cold front that will plow across the area bringing another round of showers and scattered thunderstorms this morning through early afternoon. Periods of MVFR/IFR will be possible within any heavier showers/storms. Showers will quickly taper off from west to east behind the cold front, with mainly MVFR CIGS scattering out from the Finger Lakes westward, although MVFR CIGS may hang on toward KIAG and KART. There may also be a few additional localized showers and storms this afternoon associated with any lake breeze circulations. Otherwise, another period of widespread MVFR CIGS will be possible later this afternoon through this evening, but CIGS will start to scatter out across western NY toward the tail end of the TAF period.

Strong southwest winds will be the other main impact today, with widespread gusts of 35-45 knots. The highest gusts will be northeast of the lakes (KBUF/KIAG over to KROC and toward KART). Winds will come down this evening with west to southwest gusts mainly in the 15- 25 knot range by the end of the TAF period.

Outlook...

Friday through Sunday...Mainly VFR. A chance of a few isolated to widely scattered showers and thunderstorms at times with local/brief restrictions.

Monday...Mainly VFR. Showers and a few thunderstorms possible.

MARINE
A strong sfc low tracking north of the lakes today will cause winds to increase out of the southeast ahead of the approaching system. As the sfc low tracks east-northeast, winds will veer to the south and then southwest this morning. Gale force winds are expected on Lake Erie with higher end small craft winds expected on Lake Ontario. All marine zones, including the Niagara & St. Lawrence Rivers have at least Small Craft Advisories in effect, with Gale Warning for Lake Erie. Details and timing can be found below.

Winds will become mostly westerly behind a passing cold front and are expected to remain elevated through the rest of the work week on the lakes with Small Craft Advisories either in place through Friday or likely being added after Gale Warnings drop. This will be due to the slow track the strong sfc low will be taking as the system tracks across southeast Canada. The pressure gradient will remain strong over the region under the influence of the sfc low still nearby.

TIDES/COASTAL FLOODING
An unseasonably strong low pressure system will move from the central Great Lakes to southern Quebec through this evening, on a classic track to produce strong winds across the eastern Great Lakes.

The combination of above average lake levels, strong west- southwest winds, and significant wave action may bring an increased risk of minor lakeshore flooding at the east end of Lake Ontario this afternoon through Friday. Forecast winds and waves are currently near the low end of the established threshold for lakeshore flooding. A Lakeshore Flood Warning has been issued for Oswego and Jefferson counties. Impacts are expected to be minor.

Flooding is most probable in low lying shoreline areas from northern Oswego County into Jefferson County. Water levels may also rise along the Saint Lawrence River in the Thousand Islands region as strong southwest winds force an increased flow of water down the river.

BUF WATCHES/WARNINGS/ADVISORIES
NY...High Wind Warning until 8 PM EDT this evening for NYZ001>003- 007-008-010>014-019-085.
Wind Advisory until 8 PM EDT this evening for NYZ004>006.
Lakeshore Flood Warning from 2 PM this afternoon to 8 PM EDT Friday for NYZ006-007.
Wind Advisory until 8 PM EDT this evening for NYZ020-021.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LEZ020.
Gale Warning until 6 PM EDT this evening for LEZ040-041.
Small Craft Advisory until 8 PM EDT this evening for LOZ030.
Small Craft Advisory until 8 AM EDT Saturday for LOZ042.
Small Craft Advisory until 2 AM EDT Sunday for LOZ043>045.
Small Craft Advisory from 8 AM this morning to 10 PM EDT this evening for SLZ022-024.