HOLDEN BEACH, North Carolina—Florence, the most powerful storm to menace the U.S. mainland this year, intensified into a Category 4 hurricane as it howled closer to the Carolinas on Sept. 10, prompting evacuations of more than 1 million people to higher ground.
Packing maximum sustained winds of 130 miles per hour, the storm was due to gain even greater strength before making landfall early on Sept. 13, bringing heavy rains with the potential to unleash widespread, severe flooding, according to the National Hurricane Center (NHC) in Miami.
