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.

MIAMI — Tropical Storm Erin formed Monday in the eastern tropical Atlantic Ocean, just west of the Cabo Verde Islands, as Hurricane Henriette strengthened in the Pacific Ocean well away from Hawaii, forecasters said.

Tropical Storm Erin formed Monday in the eastern tropical Atlantic Ocean and could become the first hurricane of the 2025 Atlantic season later this week, forecasters say. In the Pacific Ocean, Hurricane Henriette strengthened well away from Hawaii.