It looks like our January thaw may arrive in late December.
The upper-air pattern over North America strongly suggests milder than average temperatures in the Midwest over the next two to three weeks. We may feel a couple of cold fronts in the next three weeks, but the overall flow suggests Pacific air masses could dominate into early January.
Meteorologists call it zonal flow. It occurs when winds blow more directly from west to east across along latitudinal lines.
Zonal flow patterns in winter bring milder Pacific air masses to Minnesota and most of the United States.
Upper-air forecast maps over the next few weeks strongly favor zonal flow patterns with polar front jet stream displaced northward into Canada. This pattern blows milder Pacific air and thaws to Minnesota in winter.
Bathed in red
The National Oceanic and Atmospheric Administration’s medium-range temperature outlooks are bathed in red across the U.S. into early January. The six- to 10-day outlook strongly favors higher-than-average temperatures overall through Christmas Day.
The eight- to 14-day outlook keeps the warm bias going into the last week of December.
And NOAA’s week three- to four-week temperature outlook suggests the mild pattern may persist into early January.
The average high and low on Christmas day for Minneapolis are 25 and 10 degrees. Temperatures at least 10 to 15 degrees warmer than average overall look likely in the next two weeks.
A shot at 40?
Some of the medium-range temperature guidance suggests we could see temperatures near 40 degrees in southern Minnesota over the next two weeks.
NOAA’s Global Forecast System Long-Range Model Output Statistics (MOS) Forecast for the Twin Cities cranks out a string of at least five days of highs in the 30s starting Thursday. The output suggests temperatures in the upper 30s to near 40 degrees next weekend.
NOAA’s GFS 16-day plot suggests some colder days punctuated by another warm surge around Dec. 26-27.
Forecast models often underestimate extreme temperature swings. I won’t be surprised to see highs well into the 40s across parts of Minnesota in the next two weeks.
Keep in mind there may still be a few colder days in the next few weeks. But the overall pattern strongly favors a mild bias.