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It's not your imagination: Minnesota weather's getting weirder and wetter

The geezers might be right on this one. Minnesota's weather really is different now.

The geezers might be right on this one. Minnesota's weather really is different now. ekbph/Instagram

If there's anything more boring than someone talking to you about weather, it's someone talking about what the weather used to be like, back when they were a kid.

Thing is, lame or not, there's some truth to those stories. It is different now. In Minnesota, that should be cause for concern.

Scientists wouldn't blame the fast-moving thunderstorms that swept through Minnesota Thursday on climate change.

Nor would they ascribe responsibility to long-term climate shifts for another set of "severe storms" expected today. 

 

No one big weather event is directly the fault of climate change, in the same way your Fox News-loving uncle is wrong to Facebook that April's blizzard proves the whole thing is a hoax perpetrated by "China people." 

What scientists can say, with confidence, is that Minnesota is getting positively dumped on more often these days, compared to what the state used to experience 100 years ago. And it's causing "big problems."

The change is the subject of a story out last week from FiveThirtyEight, the predictive and analytics website, which uses Minnesota as a case study in how the whole of the Midwest is getting "drenched." The story looks not at cumulative precipitation, but at major one-time rainfall events, which happen far more often now than they used to.

These storms leave the state more vulnerable to flooding, and not just the kind we expect, where spring snowmelt fills the Mississippi or other rivers over their banks. 

Large, unexpected rainstorms that dump inches of water at a time. Minnesota's summer of 2016 was a freakishly wet one. One August rainfall dropped close to 10 inches near Willmar. Six weeks later, another huge storm dropped more than eight inches on Maple Grove.

That year, 2016, was the third time in state history Minnesota experienced two "mega-rain" events, defined as "at least 6 inches of rain... over at least 1,000 square miles," with eight-plus inches in the center. (The other years with multiple "mega-rains" were 2002 and 1975.) 

That late September storm, the one that flooded cars in Maple Grove and homes in Waseca? That didn't even qualify as a mega-rain. Another enormous system in July had delivered six-plus inches over a 2,000 square mile stretch of Minnesota and Wisconsin. The storm was bigger than Delaware.

"It's getting weird," says Hennepin County emergency management director Eric Waage. 

And weird means scary. The most alarming insight in FiveThirtyEight's report come from a Minneapolis engineer named Erin Wenz, who observes that a lot of infrastructure built in the past few decades was made to withstand rare weather events -- but "rare" by 1970s standards.

Things have changed, already, since then. What projections from the 1970s considered a "100-year storm" (or one with a 1 percent chance of occurring in a given year) would be expected to occur more often; and the real 100-year storm of today would be significantly worse.

As the story goes:

[E]ven the new data isn’t perfect. While it’s much better than 40-year-old data, it’s still based on how much rain has fallen in the past. The estimates do not take into account how climate change might influence precipitation in the future. It’s a little like trying to use a road map while driving on a highway that’s still being built. The map may give you a perfect picture of the roads you’ve already traveled, but it can’t give you more than a general idea where the new highway is taking you.
According to Wenz, while the design standard has been to build roads, buildings and other infrastructure in a way that can withstand a hundred-year storm, some engineers are considering whether it’s time to build for a 500-year storm, with the expectation that soon it might no longer be such a remote possibility.

Read the whole story at FiveThirtyEight. Try to get through it before these huge storms come through today and knock out your power.