Marine Weather Net

Lake Ontario - Mexico Bay to the Saint Lawrence River Marine Forecast


OVERNIGHT

E
WINDS
10
KNOTS

TUESDAY

SE
WINDS
5 - 10
KNOTS

TUESDAY NIGHT

S
WINDS
5 - 15
KNOTS

WEDNESDAY

SE
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
LOZ045 Forecast Issued: 1002 PM EDT Mon May 12 2025

Overnight...East Winds 10 Knots Or Less. Partly Cloudy. Waves 1 Foot Or Less.
Tuesday...Southeast Winds 5 To 10 Knots Becoming South. A Chance Of Showers In The Afternoon. Waves 1 Foot Or Less.
Tuesday Night...South Winds 5 To 15 Knots Becoming Southeast. A Chance Of Showers In The Evening. Waves 1 Foot Or Less.
Wednesday...Southeast Winds 10 To 15 Knots. Mostly Cloudy. Waves 2 Feet Or Less.
Wednesday Night...Southeast Winds 5 To 15 Knots. Mostly Cloudy. Waves 1 Foot Or Less.
Thursday...Southeast Winds 10 Knots Or Less. A Chance Of Showers. Waves 1 Foot Or Less.
Friday...South Winds 5 To 10 Knots. Showers Likely. Waves 2 Feet Or Less.
Saturday...South Winds 5 To 15 Knots Becoming Southwest. Showers Likely. Waves 1 To 3 Feet.
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Area Forecast Discussion
National Weather Service Buffalo NY
719pm EDT Monday May 12 2025

Synopsis
High pressure will slide southeast off the east coast, maintaining dry weather through the evening. A broad diffuse area of low pressure and moisture will then spread northward across the Ohio Valley and Great Lakes. This will bring a chance of a few showers starting Tuesday and lasting through the end of the week, but there will be plenty of dry time built in as well.

Near Term - Through Tuesday
Surface high pressure will slide off the east coast, while upper level ridge axis arcs back northwest from the western Atlantic overhead the area. These features will maintain dry weather, with just an increase in upper level clouds through this evening as they spill northward over the aforementioned upper level ridge axis. Forecast temps on track with most areas seeing readings in the mid to upper 70s, with some low 80s in the Genesee Valley/Finger Lakes region...while areas closer to the lakeshores remain cooler, and in some cases much cooler close to the lakeshore, with an onshore flow owed to weak gradient flow.

Upper level ridge axis slides northeast of the area tonight, allowing a large, but weak upper level low over the lower Mississippi Valley to start lumbering northward. It will reach the mid Mississippi Valley tonight, then drift northeastward into the lower Ohio River Valley by later Tuesday. With this in mind, expect dry weather to prevail area wide through at least late evening. Moisture will then be on the increase from south to north later tonight, especially across the Southern Tier with a chance of showers getting into southwestern NY after midnight. Showers become likely across southwestern NY late tonight, with low Probability of Precipitation chances reaching north to near Buffalo/Niagara Falls by around daybreak. Areas north and east of here remain dry through the night. One caveat...there is a plethora of dry air in the low levels this moisture will have to saturate before raindrops can actually reach the ground, so that could delay the start time some. Much warmer tonight with lows generally in the 50s.

Deeper moisture will advance northward across most of the forecast area south of Lake Ontario as the upper low moves into the lower Ohio River Valley Tuesday. Meanwhile, the upper level ridge axis will remain anchored from southern New England northwest across northern NY, while a backdoor cold front sags southwest toward far northern NY. In terms of sensible weather, will likely see periods of showers across the western Southern Tier, with more in the way of less persistent showers north of the Southern Tier to Lake Ontario. Can't rule out a rumble thunder in the afternoon, however instability looks marginal. Otherwise, the North Country may remain dry through the entire day with upper level ridge axis arcing back across northern NY and the center of surface high pressure sliding southeast across New England. Highs will be the warmest in the mid to upper 70s across the North Country, with the coolest temps in the mid to upper 60s across the higher terrain of the Southern Tier under the clouds and precipitation.

Short Term - Tuesday Night Through Thursday Night
A closed mid level low currently over the deep south will slowly track northeast to the Ohio Valley by Tuesday night and Wednesday morning. During this time, the mid level low will weaken and open to a negatively tilted mid level trough. The axis of the mid level trough will center over Lake Erie and the central Great Lakes by Thursday morning, slowly continuing to weaken as it tracks northeast to northern NY and southern New England by Thursday evening.

As the mid level low and trough cross the region, passing shortwave troughs will help increase the potential for showers and some thunderstorms, especially if timing lines up well with peak daytime heating. Increased dewpoint values will also contribute to the potential for showers and thunderstorms as instability increases during the middle of the week. With the weakening nature of the mid level low and trough, showers and thunderstorms should be more scattered and less persistent/steady. While there will at least be a chance for showers/storms during most of the period, potential for showers/storms will increase from north to south.

Temperatures during the short term period will remain above normal with highs in the low 70s to low 80s for most locations.

Long Term - Friday Through Monday
The warm front of an occluding area of low pressure over the upper Midwest will track across the region on Friday morning, bringing the potential for additional showers. Guidance brings some drier air into the region during the day on Friday ahead of the cold front for Saturday morning, so that will cut down on some of the shower potential for the day. The systems cold front will then cross the region on Saturday morning, continuing the potential for showers.

The surface and mid level low along with the mid level trough of the system will then track southeast, near or just north of the forecast area, continuing the potential for showers through the rest of the period.

Temperatures during the period will start above normal for Friday and Saturday, and then cool to below normal behind the passing cold front for Sunday and Monday.

Marine
High pressure draped across southern New England will drift off the east coast through tonight. Expect mainly light southerly offshore flow through tonight, although weak gradient flow has allowed for an onshore flow to develop on both lakes this afternoon that will persist through early evening before diurnal heating wanes and lake breeze driven circulations cease.

Tuesday through Thursday, winds will generally be east to southeast on the lakes with a light to moderate chop at times, but no Small Craft Advisory conditions are expected through the week. There is a low chance of thunderstorms during this time.

NOAA Buffalo NY Office: Watches - Warnings - Advisories
NY...None.

Marine
None.

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