Tornadoes can happen whenever atmospheric conditions are suitable, says Steve Ackerman, professor of atmospheric science at UW-Madison. Over the years, Wisconsin has had at least one tornado in every month except February.
“To get any severe weather, we need really warm, moist air near the ground, and cool air aloft, which is typical of the spring, [...]

To understand and protect the home planet: it’s no longer a key NASA mission. What will we lose as NASA turns its eyes toward the moon and Mars?