Marine Weather and Tide Forecast for Lewiston, NY

NEAR TERM /THROUGH TONIGHT/
Radar imagery showing widespread light rain and drizzle across Western NY, the Genesee Valley, and western Finger Lakes early this morning, with the rain more spotty east of Lake Ontario. The most widespread rain will continue to focus across the Niagara Frontier, Genesee Valley, and western Finger Lakes this morning before moving northeast and filling in east of Lake Ontario this afternoon.

A large, deep mid/upper level low stretching from the Great Lakes to New England will continue to drift very slowly east, becoming centered over Maine by Saturday morning. At the surface, low pressure will drift slowly east across Lake Ontario today before dissipating as a secondary coastal low moves north along the New England coast. Deep, moist cyclonic flow will continue across the eastern Great Lakes today through tonight. A northwest to southeast oriented frontal zone and axis of low/mid level deformation will continue to be the primary focus for widespread rainfall today through tonight, with this feature becoming focused over and southeast of Lake Ontario today. This will maintain widespread light rain and drizzle for much of the area today into the first half of tonight before the rain diminishes somewhat in coverage late tonight as the best forcing and moisture begin to drift east.

Across the western Southern Tier, rain will become more intermittent and showery today as the deformation zone moves northeast towards Lake Ontario. WNW upslope flow will still maintain frequent showers across the higher terrain just inland from Lake Erie, and steepening lapse rates with modest diurnal heating will also result in additional shower coverage this afternoon.

Temperatures will remain well below average today, with highs barely reaching the lower 50s for the lake plains, and mid to upper 40s across higher terrain. These values are approaching 20F below average for late May.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
Heading into the holiday weekend, a vertically stacked low pressure system will lie across the east coast of Maine, while a weak shortwave trough will track west across the upper Great Lakes and into the lower Great Lakes through the weekend. This being said, expect the chances for showers to linger throughout the weekend, with the best chances occurring each afternoon due to increasing instability from diurnal heating. Additionally a few rumbles of thunder can't be ruled out south of Lake Ontario across the Genesee Valley.

Showers will then scatter out late Sunday evening and overnight with the loss of daytime heating and a building ridge edging into the eastern Great Lakes.

The airmass overhead will continue to remain on the cooler side supporting daytime highs below normal for the first two days of the holiday weekend.

LONG TERM /MONDAY THROUGH THURSDAY/
Mid-level ridging and corresponding surface high pressure will slide across the eastern Great Lakes region Memorial Day, which in turn will support the best day to be outside for the long weekend. While the weather will remain mainly dry, a few afternoon showers inland from the lakes will be possible. Along with the nice weather, temperatures Monday will be the warmest of the holiday weekend.

Attention then turns to the next mid-level closed low developing across the Midwest and Great Lakes. Model guidance continues to remain diverged with the timing, location and strength of this feature. This being said, a slower track of this low will promote more dry weather, however a quicker paced system will support increasing chances for rain to return. For now have showers arriving Tuesday night into Wednesday morning. As this mid-level low then makes a pass across the Great Lakes mid to late in the week, the potential for showers will continue.

AVIATION /12Z FRIDAY THROUGH TUESDAY/
A broad, deep upper level low will continue to dominate the Great Lakes and New England through tonight, supporting a continuation of rain and low CIGS. The most widespread rain will focus over Western NY, the Genesee Valley, and western Finger Lakes through this morning, then gradually expand northeast, filling in east of Lake Ontario this afternoon. Rain across the Southern Tier will become more intermittent and showery late this morning through the afternoon. The misty, light rain will reduce VSBY to MVFR and local IFR at times. Widespread IFR to low end MVFR CIGS will continue today across all of Western NY. The VFR CIGS across the North Country will deteriorate to MVFR this morning, then IFR to low end MVFR this afternoon.

The widespread rain will last into this evening, then tend to diminish in coverage and intensity overnight as a surface low associated with the upper level low moves off into the Canadian Maritimes. Despite the diminishing rain coverage, abundant low level moisture will continue to support widespread IFR to low end MVFR CIGS tonight through early Saturday morning.

Outlook...

Saturday...Scattered to numerous showers. Widespread IFR/low end MVFR CIGS in the morning improving to VFR/MVFR in the afternoon.

Sunday...VFR/MVFR with scattered showers.

Monday...Mainly VFR.

Tuesday...Mainly VFR with a chance of showers.

MARINE
Low pressure will move slowly east across Lake Ontario today before giving way to a secondary coastal low along the Maine coast this evening. Moderate westerlies of 20+ knots will produce solid Small Craft Advisory conditions on Lake Erie today into this evening.

The surface low traversing the middle of Lake Ontario will make for an interesting wind pattern over the lake today, with E/NE winds over the northern half of the lake, and westerlies along the south shore of the lake that will reach 15+ knots at times. The differing wind directions will likely produce a chaotic wave pattern over the lake, with wave packets of differing direction and period.
Conditions will generally stay below Small Craft Advisory criteria, but will be choppy.

Late tonight and Saturday, expect westerlies of around 15 knots on Lake Erie and Lake Ontario, with a moderate chop but just below Small Craft Advisory criteria. Similar conditions will persist Sunday before high pressure builds into the Great Lakes on Memorial Day, with lighter winds and less wave action.

BUF WATCHES/WARNINGS/ADVISORIES
NY...Beach Hazards Statement through this evening for NYZ010-019- 085.
MARINE...Small Craft Advisory until midnight EDT tonight for LEZ020-040- 041.