|Surface map at 6:00 p.m. CST December 20|
The medium range models are still indicating a change in the upper level pattern in the next week to ten days along the lines of that shown in my December 17th post. The cold air is still bottled up in Alaska and northwest Canada. Fairbanks, for example, just experienced its sixth day in a row with lows -40F or lower and the warmest highs just reaching -19F. It appears that this cold air may be dislodged in the next week or so as an upper level ridge builds in the eastern Pacific and a trough develops across the U.S. Both the 6 to 10-day and 8 to 14-day outlooks issued today by the NWS Climate Prediction Center are indicating a higher probability for below normal temperatures across much of the country.
In addition, a series of low pressure systems moving across the U.S. in the next 10 days will likely produce precipitation in the Great Basin and/or the eastern half of the country.