REGIONAL— The extraordinarily mild weather so far this month is uncommon, but not unprecedented, according to state climatologist Pete Boulay. It was back in December of 1998, coming off one of the strongest el Niño events ever recorded, that the region saw temperatures even warmer than this year, at least over the first two weeks of the month.
A very strong el Niño is currently in place in the Pacific Ocean and it appears to be significantly affecting our weather.
Back in 1998, temperatures reached the low 50s at many reporting weather stations in northeastern Minnesota as late as Dec. 15, including a 50-degree high in Tower and a 51-degree reading near Cook on that date. Temperatures for the first two weeks of the month averaged 10-12 degrees F above average and, like this year, the ground was mostly bare. Many of the larger lakes in the region didn’t freeze-up until mid-December that year. Lake Vermilion, for example, didn’t fully freeze over until Dec. 13, the latest date on record.
This year, local reporting stations are running about 8-10 degrees above average to date, but this month is likely to finish significantly warmer overall than in 1998. That warm start to the month in 1998 was followed by a brutal cold snap that set in just before Christmas, which led to one of the most dramatic temperature changes within the month of December ever recorded in our area. Tower, which had reached 50 above in the middle of the month, bottomed out at minus-37 before the month was out, a variation within the month of 88 degrees F. The cold was so pronounced in the second half of the month that the month overall averaged within a degree or two of normal despite the extraordinarily warm start.
That late December cold wave was likely facilitated by the rapid onset of a la Niña pattern, which cooled off much of the rest of the winter. But there’s no sign of that this year—just a strong el Niño pattern. In fact, there’s no sign of any significant change to our remarkably warm and dry December as of this week, with temperatures forecasted to continue warm with little or no snow for the foreseeable future.
Indeed, the 8-14 day outlook from the Climate Prediction Center, shows the Upper Midwest, including all of Minnesota with an 80-90 percent probability of above-normal temperatures.
The average high for December 15 in Tower is 21.7 degrees, with an average low of 0.5 degrees F.