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 has formed in the Atlantic Ocean and is expected to strengthen to a Category 3 hurricane by the weekend, potentially causing strong rip currents and large waves on the East Coast beaches.

Tropical Storm Erin formed in the eastern Atlantic Ocean on Monday, forecasters said. The storm could strengthen to become the Atlantic's first hurricane of the season.