OKLAHOMA CITY (AP) — Thousands of flights across the U. S. set to take off over the weekend were canceled as a monster storm started to wreak havoc Saturday across much of the country, knocking out power and snarling major roadways with dangerous ice. Roughly 140 million people, or more than 40% of the U. S. population, were under a winter storm warning from New Mexico to New England. The National Weather Service forecast widespread heavy snow, sleet and freezing rain from Saturday to from a...