The current forecast calls for Erin's winds to increase to 125 mph within five days, making it a strong Category 3 storm. A Category 4 storm has maximum sustained winds of at least 130 mph. Erin is expected to turn north at some point, staying away from Florida and the east coast of the United States.

The chances that rain and wind from Tropical Storm Erin will hit the East Coast have risen slightly this week.

In the Gulf, Invest 98L has a low chance for development, before it moves inland over northeastern Mexico or southern Texas by late Friday. The National Weather Service in Brownsville, Texas, said regardless of tropical development, locally heavy rain and increased swells "will be a concern" along the Texas coast.