Tropical Storm Erin is continuing to pick up strength as it moves across the Atlantic, with forecasters expecting the storm to officially strengthen into a hurricane on Friday, Aug. 15, according to the National Hurricane Center.

Tropical Storm Erin is nearly at hurricane strength Thursday night, its western path putting islands in the far eastern Caribbean under tropical storm watches, according to the National Hurricane

Tropical Storm Erin is expected to become a hurricane later today, Aug. 15, and a Category 4 hurricane with maximum sustained winds of 130 mph over the weekend. A major hurricane is a Category 3 or stronger, with maximum sustained winds of at least 111 mph.