At least 2,000 flights were canceled Sunday as winter blizzards continue to batter the Upper Midwest, turning at least one normally bustling airport into a virtual ghost town. According to the latest data from FlightAware, U.S. flight cancellations Sunday accounted for roughly 78% of all canceled flights worldwide, with at least 2,216 flights grounded out of roughly 2,842 global cancellations. Meanwhile, an additional 6,826 delays have reportedly rippled across the national air network, further straining travel schedules across the world. Many airlines have since issued guidelines allowing passengers to change their flights without major fees, providing flexibility for travelers affected...