Forecasters and emergency agencies prepped for a long weekend early Friday as Tropical Storm Erika wobbled toward Puerto Rico and then the southern Atlantic coast, where it could be a hurricane when it arrives early next week. A tropical storm warning was in effect for Puerto Rico and the U.S. Virgin Islands after Erika caused mudslides blamed for at least four deaths on the Caribbean island of Dominica. to the weather service, making it difficult to project its course. The storm was about 135 miles south east of San Juan, Puerto Rico, at 11 p.m. Thursday night with maximum sustained winds of 45 mph, the National Hurricane Center said.