A bitter and dangerous blast of arctic air is charging its way across almost the entire nation this week, dropping wind chills to as low as between negative 50 and negative 70 degrees across the Northern Plains and 30 below zero in the Midwest, triggering rare Hard Freeze Warnings along the Gulf Coast, and helping fuel a monster winter storm that will bring frigid temperatures across the Great Lakes and Northeast. ... Thursday morning temperatures will be as cold as negative 29 degrees in Casper, Wyoming, with 23 degrees below zero likely in Billings, Montana – likely the city's coldest...