December, a record-warm month
Published on January 8, 2024 at 11:45am CST
View From The Cab
By David Tollefson, Columnist
I don’t have to tell any of my Minnesota or upper Midwest readers that we had an extraordinarily warm month in December.
I do get the monthly weather reports from the West Central Research and Outreach Center at Morris. Heidi Olson-Manska sends them to me by email very soon after the month ends.
Here are some of Heidi’s summaries:
“December 2023 temperatures were significantly warmer than normal with above-average precipitation and below-average snow. These above-average temperatures have produced the warmest December since our record-keeping began in 1886 at the WCROC.”
“The high temperature for the month was 58 recorded on Dec. 8. The low temperatures for the month were 11 degrees on Dec. 1, 18, and 19th.”
“Four high-temperature daily records were broken in Dec. of 2023. On Dec. 8, we recorded a high of 58, breaking the previous record of 57 in 1939. On the 15th we recorded a high of 54, breaking the previous record of 50 on the same date in 1939. On the 24th, we recorded a high of 49, breaking the previous record of 44 on the same date in 1943. On the 25th, we recorded a high of 49, breaking the previous record of 49 on that date in 1922.”
“Rain for the month totaled 3.46 inches, 2.77 inches above the average of .69 inches. A total of .3 inches of snow fell in December, compared to the average snowfall in December (1886-2022) of 7.12 inches.”
The rain measured at my place was similar to that in Morris, according to my electronic gauge (the actual tube gauge was long put away-they don’t survive freezing very well). And I recorded one-half inch of measurable snow, although there were a few of what I might call “dustings.”
In the Jan. 3, 2024 column by John Baranick, meteorologist with DTNAg, gives some technical background to the reasons for these unusual temperatures. Here it is:
It was mentioned in this blog space before it began, but December turned out to be a really warm month for most of the United States and Canada.
In fact, based on data gathered by the Iowa Environmental Mesonet, it was the warmest December on record across all climate districts in Minnesota and a few others in the Upper Midwest. Most of the climate districts across the northern tier of the U.S. that are east of the Rockies were in the Top 5 warmest. And even much of the Central and Southern Plains and portions of the West were in the Top 10. Only one climate district in the contiguous U.S. had a below-normal month – the one that includes Mobile, Alabama. The data record goes back 132 years to 1893. Southern Canada also had a very warm December, though data is not available to rank.
The cause of the record warmth has been an upper-level ridge of high pressure that persisted almost the entire month across most of the U.S. and Canada. Occasionally, there were some breakdowns in the ridge, one of which brought a big winter storm system for Christmas to the Plains, but the breakdowns were short-lived.
In fact, the temperatures leading up to the Christmas storm were record-setting in the Upper Midwest. Minneapolis set a high of 55 degrees F on Christmas Eve, smashing the previous record by 9 degrees F. But it was the overnight temperatures that were even more extreme, in some cases in the 40sF across northern areas, which were 10-20 degrees F above the normal lows.
So, if the ridge was so dominant, why did the southern tier of the U.S. not join the north in the record-setting warmth? The answer was an active southern jet stream that brought several storm systems through the region but also brought down a bit more of that Canadian air into the Southeast. While any cool-down was brief in the north or the Plains, the southern jet stream kept the lower temperatures around longer in the Southeast. Cloud cover and precipitation also worked to keep temperatures down in the region. But outside of the Mobile area, most areas in the Southeast were near or even above normal for the month.
And typically, if the eastern half of the country is warm, the western half is pretty cool. That was not the case this year as several climate districts in the West saw a Top 10 warm December.
The very warm northern U.S. and somewhat cooler southern U.S. is a typical feature during El Nino. Almost all El Ninos, regardless of strength, produce a very warm December. It just so happens that very strong El Ninos, which we are currently experiencing, are even more likely to produce warmer readings, sometimes to the extreme. December 2015 was one of those strong El Nino years where temperatures were extremely warm for a vast area of the country. In that year, it was mostly in the Eastern U.S.
January has continued to show that warm ridge across the U.S. and Canada, but that is about to change for mid-month.
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Several of us southern Pope County farmers are often texting rainfall or snowfall amounts. But with these warm temperatures, you would not believe what we are texting about now: pocket gopher trapping!
If you know anything about pocket gophers, they’re supposed to be burrowed deep in the ground at this time of the year, waiting for warm weather in the spring to do their damage to alfalfa fields, CRP and other crop land.
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Please contact David Tollefson with thoughts or comments on this or future columns at: adtollef@hcinet.net