Over 200 million people across the United States are under a winter weather advisory today, with the National Weather Service warning of a “once-in-a-generation” cold weather event ahead of the holiday weekend. Parts of the Midwest have received more than a foot of snow, with millions facing whiteout conditions and “life-threatening” wind chill advisories. Hundreds of thousands of homes and businesses have lost power. So far, more than 5,600 flights have been canceled due to the storm; nearly 10,000 flights have been delayed.