NATION IN BRIEF : THE NORTH : Mercury Plunges in Rockies, Plains

Temperatures dropped to record lows over the northern Rockies and Plains, and up to seven inches of snow fell on parts of Michigan’s Upper Peninsula. Morning low temperatures below freezing were common from the northern and central Rockies to western Upper Michigan, with lows in the teens in the Dakotas. Record lows were 18 at Casper, Wyo.; 12 at Dickinson, N.D.; 14 at Rapid City, S.D.; 14 at Sheridan, Wyo., and 9 at Williston, N.D., the National Weather Service said. A winter storm warning was issued for parts of central Upper Michigan near Lake Superior, where up to 10 inches of snow was possible.