December finished with well above average temperatures with some parts of northwestern Minnesota recording temperatures around 10° above average for the month.
In rank, December 2015 finished as the 4th warmest on record in Fargo Moorhead, the 11th warmest in Grand Forks, the 21st warmest in Williston and the 30th warmest in Bismarck. The positive temperature anomalies were higher in the east, plus, the eastern part of North Dakota and northwestern Minnesota are also a colder climate helping to explain the much higher ranking of December anomalies in the Red River Valley than in central and western North Dakota.
January has also started mild with temperatures remaining well above seasonal averages, but all of this is about to change this upcoming weekend.
The current ridge in the mid-levels of the atmosphere (500 mb) will push east into the North Atlantic allowing a piece of the “polar vortex” to slide into the upper Midwest and then only slowly move out.
This will draw in the coldest air of the season to the north central part of the United States. Indications are for several days with maximums potentially not rising above 0 and on days with a positive maximum, the odds are it will only be in the single digits above. One limiting factor to the cold potential will be the lack of a deep snow cover over the region. Last winter you may recall temperatures in the southern one-half of North Dakota had a difficult time dropping below the -10s with the lack of snow pack and that may be the case this time as well. Northern North Dakota, not only because of the colder climate, but because some areas have more snow cover would have a higher likelihood of lows in the -20s or perhaps even around -30° as this air mass is expected to have that potential.
The transition from the “warmth” through Thursday and the Arctic blast of the weekend, will come with some snow. Light snow on and off is expected both Thursday and Friday that may add up to a few inches in spots. Not a big storm, but enough to make travel difficult, plus, travelers to Frisco, TX for the Bison game will also have to deal with this event from North Dakota to Nebraska, with temperatures probably warm enough for rain Kansas and south. So if you are traveling this week, especially Thursday or Friday to Texas be aware of these possibilities.