Strong northwesterly winds aloft from the North Pacific combined with Arctic air masses near the surface are sweeping over much of the United States east of the Rockies. Weak storm systems riding the flow are heralded first by high flying cirrus clouds. "Warmer" air drawn over the cold arctic air mass is lifted and creating middle and low cloudiness.
At the surface low pressure is tracking east and southeast across the Upper Midwest. Ahead of the system light snow is falling. Behind the system the next surge of reinforcing cold air flies southeast behind another Arctic cold front.
The high flying cirrus are the first sign of the next snowfall.
As air drawn into the storm system is lifted over the colder air moisture condenses and snow begins to fall from nimbostratus.
This pattern is gradually laying down snow cover across the Midwest. The snow cover is enhancing the cold air by reflecting sunlight back to space during the day and on clear nights, radiating heat to space. It all adds up to a cold pattern for the foreseeable future.