A lobe of the polar vortex, a ring of freezing air typically found near the North Pole, will once again move into the central and eastern states this week, bringing some of the coldest air of the winter season so far — and even helping fuel yet another winter storm in coming days.

An Arctic blast tied in part to the polar vortex is driving record frigid air south from the Northern Plains toward the Gulf Coast Tuesday in a cold snap that will last the entire week. Threat level: This event is forecast to set records for the coldest temperatures on record for this late in the season,