Minnesota seeing more big rain events, less extreme cold
Records show that our temperatures are rising and the frequency of big rain events is increasing, while those days of minus 30 and minus 40 temperatures are become less frequent, a state climatologist reports.
RENVILLE, Minn. — Starting Wednesday afternoon and continuing into the night, the rains fell.
One day later, the August 11, 2016 headline in the West Central Tribune summed up the flooding that resulted throughout much of Willmar as a “1,000 year event.”
Expect more of them.
Pete Boulay, climatologist with the Minnesota Department of Natural Resources, said we are seeing an increasing frequency of mega-rainfall events.
Boulay, and Todd Peterson, of the Sand County Foundation in Des Moines, Iowa, were featured speakers at the Hawk Creek Watershed Project’s annual meeting on March 9 in Renville.
Boulay said the state has been seeing temperatures rise by an average of one-half degree each decade.
Despite last year’s drought, Boulay said our weather has otherwise been trending wetter and warmer. The change is most pronounced since the 1970s. Our weather in the 1950s and 1960s was more benign or consistent, he said.
While variability and big swings remain the Minnesota norm, there are obvious trends based on more than 100 years of weather data.
During the winter, we are seeing fewer cold extremes. He pointed to the records kept by the Opjorden family at their home outside of Milan since 1897. Luther Opjorden, who continues the practice his grandfather started, records fewer days with low temperatures of minus-30 or minus-40 degree temperatures compared to his father or grandfather.
That might seem like a good thing, but Peterson and Boulay both noted that those bitter cold days are beneficial to agriculture and forestry in the state. They help keep in check a wide variety of pests, especially invasives like the Emerald Ash Borer.
We experienced some of our wettest years from 2010-2019. Areas in the Hawk Creek watershed recorded a “surplus” of moisture over the norm ranging from 30 to 50 inches during this time frame.
Our recent drought began showing itself in late 2020, but a surplus of moisture in the ground helped carry crops through the season. The drought we experienced from late 2020 and through 2021 until fall was the worst since 1987-89, according to Boulay. One of the worst droughts ever was the “one hit wonder” in 1976, which was followed by the 1987-89, 2012 and 2021 droughts.
Moisture levels in western Minnesota are recovering. Soil moisture and stream flows are back to normal, although lake levels have not yet fully rebounded from the 2021 drought, according to Boulay. Parts of eastern Minnesota are still drier than the norm. He also pointed out that to the west into South Dakota, the drought conditions continue.
Peterson, with the Sand County Foundation, said the changing climate adds to the urgency needed to adopt farming practices that reduce erosion and benefit soil health. He said we continue to lose our topsoil at 23 times the rate that soil can be formed by natural processes. Mega-rain events and other trends exacerbate the soil losses. In Iowa, the rate of topsoil loss has actually increased.
In the last 40 years, we have been losing an average of five tons of topsoil per acre per year on cultivated ground. That amounts to the thickness of a dime per year. Stack 40 dimes on top of one another and the loss is put into perspective. “We’ve lost half of our topsoil, folks,” said Peterson.
The Sand County Foundation was founded by conservationist Aldo Leopold, and focuses on working with the owners of private lands. Roughly 50 percent of the land in the U.S. is private and 70 percent of that is in agricultural use, he pointed out.
Three-fourths of the sediment the Mississippi River carries as its leaves Minnesota for the Gulf of Mexico comes from the Minnesota River basin, he said.