Lake Ontario - Open Waters from Mexico Bay to the St Lawrence River Marine Forecast
|Tonight...Southwest Winds 15 To 25 Knots Becoming West. Rain Through The Early Overnight, Then Rain And Snow Showers Late. Waves 3 To 6 Feet Building To 5 To 8 Feet. Waves Occasionally Around 10 Feet.|
|Wednesday...West Winds To 30 Knots. Rain Showers And Snow Early, Then Rain And Snow Showers Late In The Morning. A Chance Of Rain Showers Early In The Afternoon. Waves 6 To 9 Feet Building To 9 To 13 Feet. Waves Occasionally Around 16 Feet.|
|Wednesday Night...West Winds To 30 Knots Diminishing To 15 To 25 Knots. Waves 9 To 13 Feet Subsiding To 7 To 10 Feet. Waves Occasionally Around 16 Feet.|
|Thursday...West Winds 15 To 20 Knots Becoming Southwest. Waves 6 To 9 Feet Subsiding To 4 To 7 Feet. Waves Occasionally Around 11 Feet.|
|Thursday Night...Southwest Winds 15 To 25 Knots. A Chance Of Rain Showers Overnight. Waves 4 To 7 Feet. Waves Occasionally Around 9 Feet.|
|Friday...Southwest Winds 15 To 20 Knots Becoming Northwest 10 To 15 Knots. A Chance Of Rain Showers. Waves 4 To 7 Feet Subsiding To 1 To 3 Feet. Waves Occasionally Around 9 Feet.|
|Saturday...Northwest Winds 5 To 10 Knots. A Chance Of Rain Showers During The Day. Waves 1 To 3 Feet.|
|Sunday...Northwest Winds 10 To 15 Knots. A Chance Of Rain Showers During The Day, Then A Chance Of Rain And Snow Showers Sunday Night. Waves 1 To 3 Feet.|
| Area Forecast Discussion|
National Weather Service Buffalo NY
422pm EST Tuesday Dec 1 2020
Low pressure will move into southern Quebec this evening and then remain in place through Wednesday morning before moving away from the region. Wet snow will continue across Western NY through Wednesday morning, with minor accumulations at lower elevations and locally significant accumulations across the higher terrain east of Lake Erie. East of Lake Ontario rain will change to snow by this evening and continue through Wednesday with greater accumulations limited to the Tug Hill. High pressure will bring a return to dry weather later Wednesday through Thursday.
Near Term - Through Wednesday
Radar imagery showing widespread, mainly light snow across Western NY this afternoon, with rain showers east of Lake Ontario. The rain/snow line has been nearly stationary along the Genesee River so far today. Later this afternoon the change to snow will begin to progress eastward again as cold advection spreads into the eastern Lake Ontario region. The snow across Western NY will be fairly light through mid afternoon, then start to increase in intensity across the higher terrain east of Lake Erie by late afternoon or early evening.
Tonight the vertically stacked low will move into southern Quebec, with colder air surface and aloft wrapping around the system reaching the eastern Lake Ontario region early this evening, changing any remaining rain over to snow. From this evening through Wednesday the precipitation will mostly be snow, although a few raindrops may still mix in along the immediate lakeshores as the warmer lake waters warm the boundary layer by a few degrees.
A well defined spoke of vorticity will orbit the closed low and cross the eastern Great Lakes tonight, combining with deep moisture and cyclonic flow to produce fairly widespread synoptic scale snow of limited intensity. High resolution model guidance suggests a brief burst of moderate snow is possible across the Niagara Frontier, including Buffalo, this evening as DPVA maximizes and interacts cooperatively with Georgian Bay and Lake Huron upstream connections.
The heaviest accumulations are still expected to focus across the higher terrain east of Lake Erie, with the majority of that accumulation coming from late this afternoon through the pre-dawn hours Wednesday. Boundary layer flow will become better aligned from the WNW by this evening after the closed low moves farther away and shear decreases. This will allow for lake enhanced upslope flow to increase in efficiency this evening east of Lake Erie. The strongest upstream connection to Lake Huron will be found in NE Ohio and NW PA, but mesoscale model guidance suggests some weaker secondary banding will tie into the western Southern Tier tonight. Deeper moisture, synoptic support, and colder air aloft pulls away rapidly Wednesday morning, so expect the snow to taper off and end during the morning.
Storm total accumulations are still expected to reach a little over a foot locally along the Chautauqua Ridge along a line from Sherman to Mayville and Perrysburg, with 6-9 inches fanning out farther inland across the higher terrain of eastern Chautauqua and Cattaraugus counties and also in the Boston Hills. 4-6 inches is expected for the higher terrain in the western half of Wyoming County. Farther north, expect total accumulations of 1-3 inches for the Niagara Frontier, with local amounts of 4-5 inches in a few spots in central Niagara County. 1-3 inches is also expected in Allegany County, greatest in the higher terrain in the western portion of the county. For the Genesee Valley, most locations will see an inch or less, with 2-4 inches locally for the Bristol Hills.
East of Lake Ontario, boundary layer flow through most of tonight remains SW or even SSW, preventing lake enhancement from reaching the Tug Hill Plateau. Upslope flow will produce some modest accumulations on the southwest flank of the Tug Hill, with lake enhancement also producing some minor, slushy accumulations across Jefferson County. Boundary layer flow veers more westerly on Wednesday as the low pulls away, with a relatively brief window for favorable westerly lake enhancement and upslope flow for the Tug Hill Plateau. Snow totals on the Tug Hill may reach 4-8 inches tonight through Wednesday, with 1-3 inches for the surrounding lower elevations of the eastern Lake Ontario region.
Short Term - Wednesday Night Through Friday Night
Heading into Wednesday night, the closed low from the days prior will be stacked over southern Quebec, where it will continue to weaken and advance northward. Meanwhile, upper level ridging over the northwestern Ohio Valley and its corresponding area of surface high pressure will advance eastward toward the Atlantic. As these systems progress along their designated tracks, dry air will filter in across the region from west to east, acting to diminish the activity east of Lake Ontario Wednesday night.
With the surface high to the south and the region being on its northern periphery, dry weather associated with the high will influence the weather Thursday. Thus, expect a dry day on Thursday.
Setting the scene for Friday's weather, a shortwave trough will ride through the northern-stream longwave trough Thursday, producing a surface low over southern Canada Thursday night. As this surface low pushes east, it will pivot its associated weak cold front across the region Friday producing chances for rain/snow showers. Precipitation type will be dependent on elevation. Additionally with the passage of the front, temperatures aloft at 850mb will have cooled off enough to promote some lake enhanced snow showers Friday night for the area east of Lake Ontario. Outside of an inch or two of snowfall in the North Country, no notable snow accumulations should occur.
Long Term - Saturday Through Tuesday
A large scale northern trough over the northeast will remain in place for most of the long term period. Some better guidance agreement this afternoon with an east coast storm that will miss most of the area with just chance POPs for the eastern portion of the area for Saturday and Saturday night. This storm system will develop as the southern stream and northern stream phase over the Tennessee Valley.
A cold front associated with the northern trough will cross the area on Saturday, but as of now looks mostly dry, will keep slight chance POPs. With cold air advection behind the frontal passage, a lake response should begin to set up southeast of the lakes with a cool northwest flow. Some model spread still with just how cold 850H temps get, but most guidance gets cold enough to support a lake response, and combined with lingering synoptic moisture, and the large trough over the region and shortwave troughs crossing the region, lake response off of both lakes should be expected.
Daytime highs mostly in the low 30s over the higher terrain to the mid and upper 30s for the lower elevations.
Low pressure will reach southern Quebec this evening, then remain in place through Wednesday morning before moving away from the region Wednesday afternoon and night. West winds will increase to around 30 knots on Lake Erie tonight through Wednesday, and Wednesday through Wednesday evening on Lake Ontario. There will be gale force gusts through this period, but sustained winds are generally expected to peak just below gale force. The winds will produce high end Small Craft Advisory conditions on both lakes through Wednesday night, with lower end Small Craft Advisory conditions then lasting into Friday as the pressure gradient only slowly relaxes.
NOAA Buffalo NY Office: Watches - Warnings - Advisories
NY...Winter Weather Advisory from 8pm this evening to 7pm EST Wednesday for NYZ006>008. Winter Storm Warning until 1pm EST Wednesday for NYZ019-020- 085. Winter Weather Advisory until 1pm EST Wednesday for NYZ012.
Small Craft Advisory from 7am to 10pm EST Wednesday for LEZ020. Small Craft Advisory until 6pm EST Thursday for LEZ040- 041. Small Craft Advisory from 7am to 10pm EST Wednesday for LOZ030. Small Craft Advisory until 6pm EST Thursday for LOZ042>045.