INDIANAPOLIS (AP): Meteorologists are tracking a so-called derecho weather pattern in the Midwest that could spawn severe windstorms in major metropolitan areas with gusts as strong as 100 mph. The National Weather Service says derechos occur once or twice a year in the central U.S. with winds of at least 75 mph. The storms maintain their intensity for hours as they sweep across vast distances, and can trigger tornadoes and large hail.