A number of northwest Iowa counties are under blizzard warnings as a powerful winter storm rolls through the area. The National Weather Service has put towns including Sioux City, Storm Lake, and Denison under a blizzard warning. Mason City and Fort Dodge are under winter weather advisories as the wind will gust 40- to 50-miles per hour. Snow totals range from up to a foot in Spencer to up to 18 inches in Sioux City.