Weather Whys: How does lake effect snow form?

 

Lake effect is something that can either hammer southeast Wisconsin or stay away from us completely - it all depends on the atmosphere and how if all the right ingredients come together. Today's Weather Whys answers the question: How does lake effect snow form?

The biggest weather ingredient you need is the right wind direction. For lake effect snow to form in southeast Wisconsin you need a NE or ENE wind. Anything that's too north will take that lake effect into Chicago and NW Indiana. A NE wind is not as common as a NW wind which is why southwest Michigan gets hit with lake effect much more often than southeast Wisconsin.

In addition to the right wind direction the temperature difference between the colder air moving over the warmer water needs to be at least 13°. This forms enough temperature difference to get condensation to form causing the clouds and our lake effect snow. We haven't had a whole lot of lake effect snow yet this year and the temperature difference is a big reason why since the "cold air" moving over Lake Michigan has been too warm. We also need a non-frozen lake so in winters when Lake Michigan completely freezes the lake effect snow machine shuts off.

Weather Whys is a segment by Meteorologist Justin Thompson-Gee that airs during the CBS 58 News on WMLW - The M from 7 a.m. to 8 a.m. The segment answers viewer weather questions, explains weather phenomena and reveals interesting weather stats. To submit your question reach out to Justin on Facebook, Twitter or by emailing him at [email protected].