The winter of 2011-2012 was the warmest on record in Fargo Moorhead. It was nearly 10 degrees above the current 30 year average.
There is no doubt that the overall pattern last winter was a mild one. The upper level wind pattern was consistently from the west allowing mild Pacific air to dominate the season with only a couple of intrusions of Arctic air disrupting that pattern. But another very important element to the warmth was our lack of snow cover. This past week has been a prime example.
Fargo Moorhead missed the big storm earlier this month that left a significant snow cover over central and northern North Dakota. The eight days following the storm the average high in Fargo was 40 degrees, but in usually warmer Bismarck with a snow cover the average high was just 32 degrees. Even Grand Forks with minimum snow from the storm (like Fargo), the nearby snow pack lowered their average to just 33 degrees.
Because the sun angle is so low this time of year making it difficult to melt much snow, an early season snow storm can in turn, influence the average temperature for the entire cold season.
Current snow cover over the area.