Like many storms that have struck the U.S. in recent years, Barry’s biggest threat comes in the form of torrential rain and flooding. Rainfall totals could reach 10 to 20 inches in southern Louisiana. Storm surge is expected to reach three to six feet on top of normal tides. The Mississippi River is expected to rise precariously close to the maximum height of some of the levees that protect New Orleans. Even if the levees aren’t overtopped by floodwater, their failure could inundate parts of the city.