The water reared up and slammed onto the sand like an ambush predator. Then it withdrew, and came back. Again and again the surf attacked the beach, and exploded over a nearby concrete breakwater. White gulls stood out against a dull sky as they fought to stay aloft in winds that had gathered strength over hundreds of miles of open water. The National Weather Service had issued a gale warning, an alert used only for marine locations. But this wind advisory wasn’t for the coast along Cape Cod or California,…