The first plowable snow will fall across parts of the Finger Lakes, especially later Sunday into Monday.
It will be hard to imagine the first blast of winter is on our doorstep over the next two days. Temperatures Friday and Saturday will soar into the 60s under sunny skies and a southerly wind.
The mild, enjoyable weather will come crashing down as a cold front crosses the region Saturday afternoon. As the front moves through, temperatures will drop extremely fast. Within an hour of the frontal passage, the temperature will likely drop from the mid or upper 60s to the low or mid 40s.
Behind the front, light rain and eventually snow showers will move in. Low pressure will develop to the east, setting the stage for a prolonged period of lake effect snow Sunday through Tuesday.
Let’s get into the details of the two main evolution of this this event: Saturday night into early Sunday, and Sunday through Tuesday.
Saturday Night Snow
As cold air floods into the Finger Lakes, rain and snow showers behind the cold front will move into the Finger Lakes. After midnight, as low pressure develops to the east, the precipitation may become more widespread and steadier.
Generally speaking, at this stage in the storm’s evolution, elevation will be an important factor.
Temperatures over the higher elevations of southwest New York and central New York will fall to near freezing Saturday night. This should lead to a couple of inches of snow accumulation.
The remainder of the Southern Tier and southern Finger Lakes will see a rain snow mix as temperatures fall to the mid 30s. Some areas could see a coating to an inch of snow.
Further north, temperatures will be warmer, so little to no snow accumulation is expected Saturday night as most of the precipitation stays rain until near dawn Sunday.
For the most part, road conditions will remain mostly wet, except perhaps secondary roads in the higher elevations, where travel could become a bit slick.
Lake Effect Snow Sunday, Monday & Tuesday
The weather will get worse on Sunday, Monday and Tuesday. Monday in particular could be problematic.
Low pressure to the east will meander around New England during this time period. In addition to supplying cold northwest winds, the extra moisture from the low pressure system will help to enhance the lake effect snow.
I am expecting a large spray of lake effect snow showers with embedded squalls to develop on Sunday and especially on Monday. A particularly heavier band may develop as Lake Ontario and the Georgian Bay, off Lake Huron, combine forces at times.
Temperatures on Sunday will generally be above freezing. This will result in a wet snow that will not blow around much as winds gust to 40 mph. Road conditions will be marginal, with some slick spots possible.
Sunday night into Monday, the temperatures should fall below freezing. Many areas may not get past 30 degrees all day on Monday. This is an important factor to consider, as the snow will become light and fluffy in the colder temperatures. Winds will continue to gust to 40 mph on Monday, creating hazardous road conditions and blowing and drifting snow.
Statistically, the first snow of the season is especially hazardous to travelers. Coming just days before Thanksgiving, I want to stress caution and warn of over confidence. Monday very well may seem like mid-winter, especially across the areas shaded in purple and pink on the map above.
Lake effect snow will continue into Tuesday, but will be lighter and more localized as the event winds down. Still, areas of difficult travel are possible, so please use extra caution.
Snow amounts for the lake effect portion of this event remain somewhat uncertain and will likely vary greatly by location. Some areas could potentially see as much as foot if a heavier band sets up and remains in place over a single location for prolonged time.
Continue to monitor the forecast for updates through the weekend and into next week.