If not for a 10-day cold snap in early February, the winter of 2020-21 likely would have been one of the warmest on record – possibly even in the top five or top three mildest winters in the region's history, said WDAY meteorologist John Wheeler. As it was, this winter is still likely in the top 15% of warmest winters.
After a winter like this one, Wheeler said he always fields questions about why the weather acted the way it did. The answer, he says, is less extraordinary than people tend to think.
"Ultimately, the fact is that our weather is just naturally very variable," he said. "Sometimes the various forces that guide the weather systems around the world conspire to bring one particular type of weather for a longer period of time to a certain region, and that has everything to do with the placement of the jet stream. But it shouldn't imply that we had a long spell of mild, dry weather because the weather has gone wrong – it simply was that the jet stream was poised over North America to deliver to the northern Plains region a lot of mild, dry air."
Much of the randomness of the weather comes from the jet stream, which he describes as a river of air circling the globe. If the jet stream is pointed toward North Dakota from the southwest, it brings stormier weather systems from Colorado; if it's pointed toward the state from the northwest, it tends to more frigid air, and so on.
For the last several months, the jet stream has been very weak, and has brought few weather systems from anywhere, Wheeler said. For much of North Dakota, this has mainly meant very little precipitation.
It may make for pleasant weather in the winter, but if those conditions persist, Wheeler said the region could run into problems this summer. Although rain showers this week in parts of North Dakota likely quenched at least some fire danger, Wheeler isn't optimistic the precipitation will amount to drought-busting rains. A continued dry season could impact agriculture and the economy and, in extreme scenarios, possibly bring water restrictions.
"The big fear for us this summer would be a jet stream that goes north of us and stays north of us," he said. "If you can imagine a worst-case scenario for North Dakota and Minnesota this summer, it would be a jet stream kind of shaped like a big W, with the middle part of that W north of Grand Forks. That would mean that the jet stream would be taking weather systems northward up the Rockies to the west of here, way up into central Canada, and then down into the northeastern U.S., and we would be hot and dry. That would be a bad scenario."
What all this past winter's weather doesn't necessarily add up to, Wheeler said, is evidence of climate change.
"You have to keep those two things separate," he said. "The warming climate is certainly there, and we see evidence of that all the time. But there were warm winters and warm springs 100 years ago, too. It's just that they're happening a little bit more often now, and the warm spells in winter happen a little bit more frequently than they used to.
"But the overall state of climate change didn't really have anything to do with the last few months and why it's been so warm. That's just been the position of the jet stream."