Lake effect snow season has arrived, with heavy snow expected this weekend into early next week!

Watches and advisories have been issued on the southern sides of Lake Superior and Lake Michigan, with alerts around Lakes Erie and Ontario likely to be issued soon as well. Snow in these areas could top 8-12" on some locations, with heavy snowfall rates likely reducing visibility at times, making travel very difficult.

How Lake Effect Works

Water has a much higher heat capacity than air, meaning it takes more time to warm up and cool down. This leads to "mild" water temperatures in the Great Lakes while the air overhead can be much cooler. As the cold, dry air moves over these areas, it's able to evaporate moisture from the lakes until it condenses into clouds and precipitation before falling out over land. Typically, we need at least a 13° F difference between the lake water and the air aloft (around 1500 m, or 4500-5000 ft) for lake effect snow to form. This weekend, the difference will be close to 35-45°!

Forecast

Lake effect snow begins to develop late Saturday as the cold air begins to filter farther south with stronger northerly flow. Sunday will see additional lake effect snow develop as the cold continues to spill in, eventually turning mixed rain and snow showers to all snow. As the winds shift slightly from the NNE late Sunday into Monday, Chicago could see some intense lake effect snow drift over downtown from the lakeshore. This is completely dependent on a shortwave around the upper-level low providing those NNE winds, so if that shifts a bit, Chicago may get missed. Other areas more certain to see some heavy accumulations include locations on the SSE sides of the lakes, and on the SE side of Lake Ontario. Winds shift back to the North and NW by Monday, bringing the heavier snow into Ohio, Pennsylvania, and New York.

Impacts to travel can be expected, especially along the I-90 corridor where major impacts are possible in NW Indiana. Make sure your vehicle is ready for winter travel with some good tread on your tires and a winter driving kit.

You can catch the latest forecast for the Great Lakes anytime by using the WeatherNation app to view the Central Regional Forecast. You can also tune in to WeatherNationTV at :30 past the hour!