A large, complex storm system will impact the Finger Lakes Monday afternoon into Tuesday. While confidence remains low in what to expect, model trends and past events offer some clues.
Confidence is high that the Finger Lakes region will be impacted by a storm system Monday afternoon into Tuesday.
A storm system will slowly track up the Eastern Seaboard. A combination of the location of the storm track and good dynamics in the atmosphere aloft will favor a period of heavy precipitation over the Finger Lakes.
Precipitation will likely spread from south to north across the region during Monday afternoon. The heaviest precipitation from this event will likely fall Monday evening and into Monday night. Lighter precipitation will likely linger well into Tuesday.
The exact timing of the onset of precipitation is not completely certain, nor is the end time.
Most areas will likely start out as some light rain Monday afternoon. From there, the forecast gets very messy, very quickly.
Major Uncertainty: Precipitation Type
What type of precipitation falls is the major question with this storm.
As the storm system imports warmer air from the Atlantic Ocean, high pressure north of New England will counteract with colder air. In addition, the falling precipitation and large-scale, upward motion of the air will also act to cool the atmosphere.
With temperatures aloft and at the surface expected to be hovering around the freezing mark, even the slightest deviation could be the difference between mixed precipitation with little accumulation and a significant snow.
Overall, the storm has been trending colder across most of the Finger Lakes over the course of the last few model runs. The chances for 6″ or more of snow are now around or higher than 50% for areas shaded in purple on the map. By virtue of the uncertainty, areas in blue certainly have a shot at 6 inches of snow, but the confidence is less.
Further east, in the orange shading, mixed precipitation is much more likely, which would greatly reduce snow totals. There is still a chance of significant snow in these areas, but the chances are much less.
Further west, less precipitation is expected to fall. This will result in a slightly warmer atmosphere with more mixed precipitation and an overall less chance at seeing enough precipitation to equal significant amounts.
The forecast confidence remains low with this system! A final forecast will be issued Monday morning with the latest details!
How to Prepare
In a worst case scenario, most of the Finger Lakes gets blanked with about a foot of snow overnight Monday. Precipitation will be lighter on Tuesday, which should allow road crews to catch up during the morning hours.
Temperatures will continue to hover near freezing throughout Monday night and Tuesday morning.. While this makes for a heavy snow that will be difficult to shovel, road conditions should improve significantly with treatment Tuesday morning.
Even in this worst case scenario, this storm will have more of a moderate, and not high impact.
Freezing rain is the least likely precipitation type for this event, which should keep icing to a minimum. Sleet, which is precipitation that falls as ice pellets, is more likely. While still slick and worthy of due caution, it is not as dangerous as freezing rain.
In a best case scenario, much of the precipitation will fall as rain with a couple inches of snow at the end. This would be a bit sloppy, but would have a relatively slight impact on day-to-day activities.