low of . Numerous airline flights were canceled and there were reports of power outages. The cold blast led to a monthly average temperature of only in Rhinelander, Wisconsin, the 8th coldest December for the state on record. Early December winter storm On December 2, a Pacific storm system entered the Western United States, and it spread heavy rain and snow from the Pacific coast to the Rocky Mountains. As the storm continued to move east, high snow totals fell in its wake. Maximum reported snowfall totals in this area were found to have occurred in Idaho, Wyoming, and Montana, where or greater were reported. High winds were widespread as well, with multiple locations in the mountainous regions of the western US reporting winds of greater than . As reported by the National Weather Service's Weather Prediction Center, the surface low reached its peak strength at approximately 6:00 UTC on December 3 while it was over western Wyoming, where a central pressure of was observed. Pre-Christmas storm complex On December 19, a strong cold front moved southward across much of the Great Plains. By daybreak on December 20, temperatures in many parts of Oklahoma had dropped to mostly between . However, despite the freezing temperatures, the depth of the cold air was rather shallow, with a depth of generally no more than . As a result of the shallow depth of the front, once the front reached parts of the higher terrain in northwestern Arkansas, the front stalled, leaving areas just ahead of the front significantly colder than areas behind it. While temperatures in much of the Plains remained at or below freezing, an upper low was forming over the Southwestern United States. As the low pushed eastward and northeastward across parts of eastern New Mexico and West Texas, it interacted with moisture over the Southern Plains; there was an unusually high amount of moisture across the area for December, and the low drew much of it over the cold air-mass near the surface. With the moisture in place, light rain began to fall in some locations prior to sunset. The rain persisted and spread from southwest to northeast overnight, with moderate rain beginning to fall across much of Southwest, Central, and northeastern Oklahoma and Southeast Kansas. By late morning on December 21, much of the rain had ended in Southwest and Central Oklahoma, where many areas had received over