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 an extreme risk of wildfires.

A powerful storm system that unleashed severe weather for millions of Americans from coast to coast this week is now taking aim at the nation’s midsection, bringing blizzard conditions to the northern Plains, thunderstorms and the threat of tornadoes to the Midwest and South and an elevated risk of wildfires to the southern Plains.

Severe weather threats persisted a day after stormy winds forced changes to Mardi Gras celebrations in New Orleans, which moved up and shortened its two biggest parades.