Snow and cold temperatures this week in the western parts of Kansas have sparked interest in what the winter might bring. Meteorologically, winter is defined as the period from December through February. As this year has shown, it is very possible to have winter conditions earlier -- as early as September in the Northwest. It is also possible for those winter conditions to persist into March or even April.
The outlook for December (the first part of the season) calls for equal chances on the temperatures. This means that it is equally likely for temperatures to be above or below average. The precipitation pattern for December is clearer, with an increased chance of above-normal precipitation. It is important to note that the outlook doesn’t indicate by how much the weather might be wetter.
As the outlook is extended to the full winter season, the temperature outlook remains neutral. However, the tilt towards wetter-than-normal conditions is stronger. The pattern continues to be strongest in the western divisions.
The El Niño continues to be strong, among the strongest on record. An El Niño generally favors wetter-than-normal conditions in the Central Plains. The ridging pattern along the western Rockies is also expected to continue. This has resulted in a split pattern, with the Central Plains as the dividing line. Warmer-than-normal conditions are to the west, while cooler-than-normal conditions are in place to the east.
Mary Knapp, Weather Data Library