( KTRS ) Forecasters are warning 63 million people in the central U.S. to have an eye out for bad weather this week as colliding air masses threaten to generate high winds and possibly tornadoes.

The threat expected for Wednesday stretches from San Antonio to Chicago to Cincinnati. Missouri, southern Illinois and northern Arkansas face the greatest severe weather threat.

The Storm Prediction Center says that the storms’ severity would be dictated by how much warm, humid air can funnel into the area before a cold front approaches from the west. It was too early to pinpoint where the strongest storms might hit. November storms aren’t unusual, but the nation most often sees its worst storms in the spring.

This year, there have been 10 deaths from tornadoes, but none since May.