Climate Central: The heat wave that has built across the eastern U.S. -- roasting cities from Memphis to Washington to Boston in a stifling blanket of heat and humidity -- has had one strange characteristic that meteorologists cannot yet explain. Rather than moving west to east, as typical weather patterns do in the Northern Hemisphere, weather systems across the country have moved in the opposite direction, like a drunken driver on a dark stretch of highway, drifting from east to west during the past two weeks....