As of the latest update, issued at 4 a.m. CDT Thursday, Tropical Storm Erin was located about 990 miles east of the Leeward Islands and was on a path to the west at 17 mph. (The next update will come later this morning, and updates will become more frequent once watches and warnings go into effect for the storm.)

Additional strengthening is forecast during the next day or so, and Erin is expected to become a hurricane on Friday. Tropical-storm-force winds extend outward up to 60 miles (95 km) from the center. The estimated minimum central pressure is 999 mb (29.50 inches).

Tropical Storm Erin is forecast to intensify into a hurricane as it brushes Puerto Rico, then turn north. Its impacts on the U.S. east coast next week are still uncertain.