Finger Lakes SnowMap Update: Noon Sunday Nov. 20

Snow accumulations will vary greatly over the Finger Lakes region, as is often the case in lake effect snow events.

Lake Effect Snow Set to Increase

So far, the first widespread, significant winter weather event of the season has behaved according to previous forecasts. A cold front moved through Saturday afternoon with a quick drop in temperature. An area of low pressure has since developed along the front and moved into New England.

This low brought widespread rain and eventually snow last night, with higher elevations seeing a couple inches of snow while the lower elevations closer to Lake Ontario still have grass showing.

Strong northwest winds have developed behind the low pressure, gusting as high as 40 mph at times. Temperatures will hold steady in the low 30s through the mid afternoon, but will drop more as the sun sets tonight.

Meanwhile, colder air continues to work in above the surface. This is already leading to an increase in lake effect snow off of Lake Huron and Lake Erie. Lake Ontario will shortly follow suit and the lake effect snow will become more widespread and heavier this afternoon.

Worst Comes Sunday Night-Monday

As temperatures drop and the snow rates increase, accumulations will start to pile up quickly southeast of Lake Ontario tonight. The heaviest accumulations will occur during the nighttime hours, but accumulating snow will continue through most of Monday.

Road conditions, which have been primarily wet thus far, will start to deteriorate after sunset tonight. The strong winds are already causing areas of blowing and drifting, and that problem will only increase tonight and into Monday.

In addition to snow drifts covering roadways, the strong winds will cause periods of near zero visibility. Please use extreme caution when traveling tonight and Monday.

The winds and snow will die down after sunset on Monday. The event should mostly be over by midnight Monday, with just some lingering flurries into Tuesday morning across the eastern Finger Lakes.

Accumulations & Uncertainties

Lake effect snow events are often tricky to forecast. The extra moisture from the low pressure over New England, and the warm ground and near freezing temperatures add to the uncertainty.

The best chance for significant snow will be near the Lake Ontario shore and into the northeastern Finger Lakes. Ten inches or more is likely across the Pink zone in the map above. The Purple shaded area is less certain, and local variability could be high. Generally, these areas should see 6-12″ of snow, but some areas could see even more.

Snow accumulations will taper off quickly to the south, with some parts of the Southern Tier seeing only a couple of inches at most.

For some areas, especially across the Dark Blue 4-8″ area, the weather may be quite variable, with periods of very heavy snow alternating with periods of little to no snow. Closer to Lake Ontario and further northeast, the snow should be steadier, but will still fluctuate in intensity.

Elevation may have a slight role to play along the south ends of the Finger Lakes, with local maximums possible near the south end of Canadaigua Lake, and in the higher terrain between Ithaca and Watkins Glen.