A powerful storm kicked up a towering wall of dust that rolled through metro Phoenix on Monday, darkening the sky, blinding drivers, knocking out power and grounding flights at one of the nation’s busiest airports. This type of storm, known as a haboob, is produced by a weather front or thunderstorm and typically occurs in flat, arid areas. Heavy rain and wind followed Monday's haboob, delaying flights at Phoenix Sky Harbor International Airport and causing some damage to a terminal roof. More t