Tropical Storm Erin formed in the Atlantic Monday morning, Aug. 11. Erin could become a hurricane by Aug. 13. Because the flooding has been a growing concern, city officials have installed emergency flood barriers along several miles of riverbanks. Flash flooding has emerged around the St. Louis region after heavy rain Tuesday afternoon.

Tropical Storm Erin formed Monday morning in the eastern Atlantic Ocean and forecasters expect it to become the first hurricane of the Atlantic season this week.