Bitter Arctic air plunged more than half the United States into a deep freeze Tuesday, including New Orleans, where the heaviest snow in decades brought dangerous conditions to the famously festive Gulf Coast city. Bitter Arctic air plunged more than half the United States into a deep freeze Tuesday, including New Orleans, where the heaviest snow in decades brought dangerous conditions to the famously festive Gulf Coast city. Environment Phys.org – latest science and technology news stories