This is a satellite picture from around 2:30 pm Thursday afternoon. It’s a great example of lake-effect. You’re looking at clear skies in Wisconsin and N. Illnois. There is snow on the ground north of a line from Dubuque to Milwaukee. You can see the clouds forming over Lake Michigan and moving into West Michigan. The wind is from the west-northwest at 10-20 mph.
This picture from the Chicago Water Intake shows clear skies and sunshine in Chicago on Thursday.
Contrast Chicago to South Haven, Michigan, where it was cloudy all day with occasional lake-effect snow flurries. The clouds and snow showers/flurries isn’t the only lake-effect. The lake also warms the air. The water temperature of Lake Michigan Thursday morning was 34.9°. When the satellite picture was taken, the temperature in Sheboygan WI was +9° and the temp. at Green Bay WI was +10°. At the same time, the temperature in Muskegon MI was 20° and Grand Rapids was 22°. The average January temperature in Milwaukee is 22.3°, while the average January temperature across the lake in Muskegon MI is 25.4°. In the summer, the prevailing west-southwest wind off the relatively cooler water makes the West Michigan shoreline cooler than the Wisconsin shoreline.
