As what‘s become Tropical Storm Alex menaced South Florida at the end of last week, the Coast Guard stopped nearly 50 people from Cuba off the Florida Keys trying to migrate to the United States in separate incidents. The stops happened between Thursday and Friday off Long Key, the Middle Keys city of Marathon and Elbow Cay in the Bahamas, the Coast Guard said. The cutter Margaret Norvell returned the 49 people to Cuba on Monday, the agency said. South Florida and the Keys are in the midst of a migrant surge from both Cuba and Haiti. Haiti is seeing the largest exodus from its shores since 200…