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.