Rain could be an issue for the Coca-Cola 600

An area of thunderstorms formed into a tropical depression Friday afternoon, and forecasters issued a Tropical Storm Warning for the South Carolina coast on the first holiday weekend of the summer. Forecasters said they expect the system's main impact will be heavy rain and dangerous rip currents. The system, which will be named Bonnie when it reaches tropical storm status with 39 mph winds, is forecast to make landfall Sunday afternoon near Charleston with top winds of 45 mph.

The storm's potential impact on the Charlotte area is still unclear. Stacy Stewart of the National Hurricane Center said most computer guidance Friday indicated the steering current that takes the storm onto the South Carolina coast will weaken Sunday. Stewart said the current forecast calls for the storm to slowly wander northward along the Carolinas' coast Sunday and Monday, while weakening.

Such a scenario would keep most of the heavy rain and thunderstorms east of the Charlotte region. But the National Weather Service office in Greer, SC, said it expects a 50% chance of showers and thunderstorms Sunday for Charlotte, and a 60% chance for Union and Cabarrus counties, closer to the storm circulation. The weather is a major factor this weekend in the Charlotte area, with more than 100,000 racing fans expected to attend Sunday evening's NASCAR Sprint Cup race at Charlotte Motor Speedway. Charlotte Observer