A huge storm system crossing the U.S. threatens to unleash tornadoes Friday in the Mississippi Valley, blizzards in the northern Plains and dry, gusty conditions in Texas and Oklahoma that pose a high risk of wildfires.

About 47 million people faced an enhanced to moderate severe storm threat from Madison, Wisconsin, to Birmingham, Alabama.

A big winter storm Lola is expected to form over the United States on Tuesday and swiftly develop as it moves over the central United States toward the east on Wednesday. An significant snow blizzard is expected over the Upper Midwest and into Ontario,