For a large portion of the Plains and West, this will be the nastiest arctic outbreak so far this season. The cold will enter on two flanks. One charge will be into the Pacific Northwest and Intermountain region. The other push will thrust into the Great Plains.
This cold front means business, with temperatures expected to remain below freezing the entire time from Saturday night through Tuesday. In addition, snow will fall west of the Cascade Mountains, and the ground could be whitened in both Seattle and Portland.
The cold that comes into Montana and the northern Plains will be even worse. From Billings to Bismarck, the temperature will never get above zero Sunday and Monday. Overnight temperatures through that part of the country will drop to 15 to 20 below.
Story by AccuWeather.com Senior Meteorologist John Kocet.