Forecasters issued a tropical storm warning on Wednesday for the Florida Gulf Coast, where preparations were being made for life-threatening flooding and fierce winds, while residents of Hawaii’s Big Island were warned of an encroaching hurricane. Some local governments in Florida have begun distributing sandbags as the unnamed tropical depression heads toward the state’s Gulf Coast where as much as 15 inches of rain could fall from Indian Pass on the panhandle along the Gulf of Mexico to north of Tampa, the National Hurricane Center said in an early morning advisory.