HELENA, Mont. — A powerful winter storm socked much of Montana with a wave of heavy snowfall on Sunday, with weekend totals climbing to 40 inches in some places, and breaking century-long daily records. Never mind that it has only just turned to fall. Gov. Steve Bullock declared a winter emergency as cars skidded off highways, communities lost power and farmers despaired at the damage to crops that were still in the ground. “It’s a February storm in September,” said Jeff Mow, the superintendent of Glacier National Park in the state’s mountainous northwest. “We’re used to this kind of storm,...