Warm winter startles even the experts
The forecasters said Minnesota was in for a cold, snowy winter. So much for that.
The skiers cried, the golfers high-fived, and the climatologists looked at the numbers in disbelief.
"I don't think anyone saw that February would go down as one of the warmest Februarys on record," said Kenny Blumenfeld, a climatologist with the Minnesota Department of Natural Resources.
Blumenfeld wasn't surprised that the winter outlook released last fall turned out to be wrong, though. "If you were a betting person, you'd make more money betting the opposite," he said, because those three-month forecasts are wrong more often than they're right, according to an analysis done by the State Climatology Office.
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It seems La Niña years — when cold pools in the equatorial Pacific — are harder for the long-term forecasts to get right, he said.
"They based their forecast for the Northern Hemisphere on that cold pool, and in a lot of areas it just didn't pan out. And Minnesota was one of those places," Blumenfeld said.
The same thing happened five years ago — you know, when we were all wearing shorts and flip-flops on St. Patrick's Day 2012 with temperatures in the 80s. It was "by far the warmest March we'd ever seen. The winter was a write-off," he said.
This winter started out pretty normal, with a run of typically cold December weather. But things soon changed. It rained on Christmas. December ended up being warmer than average in much of the state, and January followed suit, Blumenfeld said. "And then February just was ridiculous."
Temperatures soared into the 60s a couple weeks ago in the Twin Cities and southern Minnesota. Across the state, it was in the Top 10 or higher for the warmest February on record. And overall, the Twin Cities is in the midst of an 18-month streak of warmer-than-normal temperatures.
What's going on?
"We can't say we know entirely why, but we need to mention that we're undergoing a long-term warming trend going back four and a half decades," Blumenfeld said.
The trend is the strongest in winter, and February has one of the strongest warming signals of all the months. On top of that, we experienced an unusual warm swing, he said. "Right now we have both. We have the long-term trend and we're at a moment of high, warm-weather variability."
For snow lovers, the consequences of all this warming are bleak.
"The Twin Cities had more precipitation falling as rain than falling as snow this winter. It's a hard one to track, but we think this might be the first time we've ever observed that," Blumenfeld said.
The Loppet cross-country ski festival in Minneapolis had to move things around and make one of its most popular ski events a walk instead. And later in February, organizers of the largest cross-country ski marathon in North America — the Birkebeiner in northern Wisconsin — delivered fans the bad news that the official race was canceled.
"We're not going to be able to provide you a safe experience," one of the organizers said in an online video announcement.
Around the region, the simple act of walking was often not a safe experience. Blumenfeld said lots of rainy days and temperatures hovering around freezing meant slippery conditions.
"I've known more people who fell this winter than all of the winters of my life combined. That's because there have been so many different days with ice-rink type conditions," he said.
A spokesperson for Hennepin County Medical Center in Minneapolis confirmed the hospital treated more slip-and-fall injuries on snow and ice this winter than last winter.
On the other hand, our winter weather woes in the Midwest were nothing compared to what other places experienced.
"California has gotten torrential rains, really heavy rains. And originally the prediction was there was going to be less rain than normal there in California," said Cliff Mass, a professor of atmospheric sciences at the University of Washington.
Mass said the longer term forecasts are just not reliable.
"Initially we have a good description of the atmosphere, but the forecast declines in time. And so by the time you get to two to three weeks, there's extremely little skill," he said.
This winter has been a case in point, he said.
California's heavy rains caused floods and mudslides, killing several people. On the other side of the world, a heat wave in Australia killed bats, turtle hatchlings and even a healthy, 30-year-old man who was riding a dirt bike. In Chile, heavy rains and flooding cut off the drinking water supply for millions of people.
We know warming temperatures and heavy rains are associated with a changing climate. But even with that understanding, this winter was startling. What we don't know yet is whether this winter will remain an outlier, or become a new norm that won't seem unusual to our kids and grandkids when they look back on it someday.