Lights are slowly coming back in Louisiana as Isaac weakened to a tropical depression and moved slowly north from the Gulf Cost. About 28 percent of customers in the metro New Orleans had power restored by Thursday night, The (New Orleans) Times-Picayune reported. More than 397,000 customers of Entergy and Cleco were still in the dark, Web sites for both companies reported. Power to some of the customers had been restored earlier but was shut off again so utility workers could make repairs in other areas. Hundreds of crews worked through the night to restore power to customers, some of whom have not had electricity since Tuesday. In Jefferson Parish, about 4,500 customers had lights back on Thursday night while service was restored to nearly 13,000 customers in St. Tammany Parish. In St. Charles Parish, 15,664 customers were still living in the dark. In heavily flooded St. John Parish, 18,143 customers were still without power. In Plaquemines Parish, that number was 11,800 early Friday. Even as Isaac moved northward and out of the state, emergency management officials warned coastal areas were still at risk, The New York Times reported. \"This is still a powerful storm and there are a number of areas both along the coast and inland that can be affected by strong winds, storm surge and inland flooding and tornadoes,\" said W. Craig Fugate, head of the Federal Emergency Management Agency. The Hydrometeorological Prediction Center in College Park, Md., said Isaac was expected to move up the Mississippi Valley Friday, turning northeast up the Ohio River Saturday. In its final advisory at 5 a.m. EDT, the National Hurricane Center said Isaac was 52 miles southeast of Fort Smith, Ark., and 95 miles west of Little Rock, Ark., with sustained winds of 25 mph and moving north-northwest at 12 mph.