(NBC) - An arctic blast which threatens 32 million people could knock out power by coating parts of the South and Midwest with ice and send temperatures sinking by as much as 50 degrees Thursday, forecasters warned.
"A major ice storm is possible from northeast Texas into west Tennessee where ice accretions of 1/2 inch or more are possible," said Kevin Roth, lead meteorologist with The Weather Channel. He added that ice would weigh down power lines and tree limbs, potentially causing power outages as they fall.
Roth said the region faced a "good 12 to 14 hours of freezing rain and ice" as a winter storm and "surging arctic air mass meet in the southern Plains."
Although temperatures neared 80 degrees on Wednesday in the Dallas-Fort Worth area, the mercury was expected to dip into the 30s on Thursday. In Lubbock, Texas, the high Tuesday was 77. The low Saturday morning could be below 10.
A winter storm alert will be in effect for the Dallas-Fort Worth area from 6 p.m. Thursday until 6 p.m. Friday, with sleet and freezing rain expected, NBCDFW.com reported.
"The arctic air continues to ooze southward Friday possibly changing rain to ice in northwest Mississippi and central Tennessee," Roth added.
Temperatures could dip to minus 20 or worse in the northern midsection of the country, forecasters said.
Colorado homeless shelters opened extra beds as temperatures in Denver were expected to drop just below zero through Friday but remain below 20 through the middle of next week. The storm dumped several inches of snow in Denver, and parts of Colorado's mountains could get up to 3 feet by the end of the day.
Some Rocky Mountain ski resorts surpassed 100 inches of snow for the season on Wednesday.
Snowfall totals could also approach 3 feet in northeastern Minnesota, where the weather has contributed to hundreds of traffic collisions around the state.
Chicago could plunge from the mid-50s on Wednesday to the low teens by Friday night. Roth said that ice was most likely in southern Missouri and southern Illinois.
He added: "A major ice storm is possible in the lower Ohio Valley and western Kentucky with ice accretions of 1/2 inch or greater. Snow accumulations of 4 to 8 inches are possible from southern Missouri to north Ohio through Friday night."
In North Dakota, the bitter cold predicted ranged from minus 9 degrees in Missoula to minus 27 in Butte and Shelby.
In Montana, the cold spot will be the northern city of Havre, with low temperatures expected to dip as low as minus 30 between Thursday and Saturday. The city isn't expected to get warmer than minus 6 degrees during that period.
National Weather Service meteorologist Dave Bernhardt told The Associated Press last extended cold period in Montana he could recall was in the winter of 1996.
While the Northeast has escaped the worst of the weather so far, Roth predicted that "the wintry stuff will come Sunday or Monday."
By Henry Austin, NBC News contributor. The Associated Press contributed to this report.