Thousands of flood insurance claims are being filed in the wake of Hurricane Isaac, a slow-moving storm that hammered several parishes in southern Louisiana with prolonged, drenching rains and tropical-storm force winds, leaving water damage in parishes that don’t typically experience flooding, officials said. Commissioner of Insurance James Donelon said three parishes — St. Tammany, Plaquemines and St. John the Baptist — experienced an unusual amount of flooding. He said only 31 percent of Louisiana residents have flood insurance. The storm straddled the region for days, swamping homes with water up to four feet deep in some areas.