Are There Winter Tornadoes?

Dear Steve,

Why is that there are no tornadoes during the winter?

Andrew Horansky,

Cadillac, Michigan

Dear Andrew,

Actually, a tornado can and has occurred during any month of the year. Typically in the U.S., tornado season is considered March through August. However, the season never truly ends, it just slows down.

The reason why tornadoes are not often found occurring during the winter has to do with the general conditions which are conducive for thunderstorms and potentially tornadoes.

Tornadic thunderstorms thrive on warm and moist air. However, it is typically the clashing of this warm and moist air with a very dry and cool air mass which leads to storng storms. The Midwest just happens to be a nice flat region where these two airmasses can meet. Notice how nicely it correlates with where most tornadoes form or "tornado alley".

A very general weather pattern which is conducive to tornado development
Tornado Alley

However, during the winter, the general weather pattern looks like this:

Thus, the warm and moist air is cut off from the Midwest and forced farther South.

As I said, tornadoes do occur in during our winter, but you can see that the borderline of that cold and dry air with the warm and mosit air is precluded to the Southern portion of the U.S.

However, these are very general weather patterns, meaning they follow the norm or average. Weather does not always follow a norm...and that's what I love about our crazy Midwestern weather.

November 22nd, 1992- Not one, not two, not even three, but thirteen tornadoes break out over Indiana

December 9th, 1991- A tornado runs through McLean County, Illinois blowing unsuspecting railroad cars (empty) off the tracks.

Thanks for your question Andrew.