An abnormally warm second week of December kept temperatures from dropping below freezing across a large part of the Upper Midwest. This allowed for most of the snow cover to melt, which kept the boundary layer warm and moist when a storm system began to organize across the Plains on the 14th. A cold front moved into far western Minnesota during the morning of Monday, December 15th. Temperatures started to drop from the 30s into the 20s by the late morning and afternoon hours. As moisture began to surge northward ahead of the storm system, precipitation fell mostly as rain, with some sleet.
As temperatures fell below freezing, area roadways became ice covered. Area web cams and the Minnesota Department of Transportation showed ice covered roads in Yellow Medicine, Lac Qui Parle and Chippewa Counties by the afternoon.
The freezing rain, sleet and snow changed over to sleet and snow by the early afternoon in far western Minnesota, and slowly spread eastward. By sunset, most of west central, central and southwest Minnesota had snow as the main form of precipitation. By morning, an area of 1 to 2 inches of snow fell on the ice covered roadways. Some areas received around one quarter inch of ice before changing over to all snow.