A busy stretch of severe thunderstorms is underway due to record heat and now the threats are ramping up, putting major metro areas from Chicago to Nashville under threat as the country hits the peak of tornado season.

Severe weather slammed several states in the Upper Midwest Thursday, dropping a few funnel clouds and likely tornadoes in Minnesota and Wisconsin.

According to the Storm Prediction, the strongest storms could generate hail up to 3 inches in diameter (the size of baseballs and large apples) and strong tornadoes.