Florida residents preparing for a powerful wallop from Hurricane Helene hurriedly stocked up on water, food, gasoline and other essentials as officials warned of heavy rainfall and winds that could topple trees and produce life-threatening storm surges.

Helene strengthened into a Category 4 hurricane hours ahead of its expected landfall on Florida’s northwest coast Thursday night, and forecasters warned that the enormous storm could create a “nightmare” surge in coastal areas and bring dangerous winds and rain across much of the southeastern U.