Hurricane forecasters were tracking three disturbances in the Atlantic Ocean Sunday afternoon, one of which is expected to briefly become the season's fourth named storm as it moves away from the U.S. UPDATE: Tropical Storm Dexter forms in Atlantic as forecasters track two other disturbances

"The Tropics are heating up with 3 systems that we are monitoring," the agency warned, as it shared a map of the weather patterns sparking concern out at sea.