New index shows riskiest places for Minnesota's natural hazards

The Minnesota counties facing the greatest risks from a clobbering by nature's hazards — from ice storms to straight-line winds — are Ramsey, Hennepin, Freeborn and Nobles.

Those with the least: Lake of the Woods, Koochiching, Carver and Sherburne.

That's according to a new analysis by the Federal Emergency Management Agency (FEMA). Six years in the making, the "National Risk Index" is FEMA's most comprehensive measurement of community risks from 18 natural hazards.

The free data set goes well beyond measuring the frequency of disasters and dollar loss of buildings to interpret how vulnerable a county's residents are, and how well they can bounce back when disaster strikes. It accounts for the percent of a population living in nursing facilities, for example, or that live in mobile homes or have no health insurance.

But it doesn't project risks from climate change. And it is not a game-changer, some note, for a state with robust hazard planning. Minnesota already has a 300-plus page compendium of doom called the State Hazard Mitigation Plan.

Almost all counties have their own, too. They're required in order to apply for some kinds of FEMA funding, and counties are supposed to update them every five years, said Stacey Stark, associate director of U-Spatial, a special mapping unit at the University of Minnesota.

Even so, FEMA's new risk index is easy to use and could help communities update their emergency operations plans, pinpoint areas needing work, prioritize resources and educate homeowners, FEMA said. For instance, one reason Freeborn, on the Iowa border, ranks so high on Minnesota's risk list is because of projected agricultural losses from severe weather.

The index may be most valuable in rural parts of the country lacking the staff and resources to deeply analyze their particular risks on their own.

"We're trying to formalize a lot of information that wasn't accessible in an easily digestible format for people," said Nick Shufro, FEMA's deputy assistant administrator at the Federal Insurance & Mitigation Administration, Resilience.

Eric Waage, director of Hennepin County Emergency Management, welcomed the data even though his group does plenty of its own risk assessments, such as a recent one on landslides. "Any time that there is a new way of looking at things, it's great."

Heidi Roop, a climate scientist at the U's Department of Soil, Water and Climate, said the information could be powerful when lined up with climate change related reports.

Minnesota fares pretty well on a national scale, particularly when compared with high risk areas like Southern California. The state may be well known for suffering weather extremes, from suffocating summer dew points to arctic blasts, but its overall risk score puts it in the middle of the pack. Only four Minnesota counties even get an overall "relatively moderate" risk rating.

Los Angeles County is the country's No. 1 for overall risk from natural hazards.

"Minnesota's looking largely OK on a national level," said Kenneth Blumenfeld, senior climatologist in the State Climatology Office.

One of the state's top threats is strong winds, which have a broader footprint than more surgical tornadoes. They include straight-line winds, for example, and the more powerful, long-lasting derecho winds.

"There's a lot of ways you can get your shed blown over," Waage said.

It was no surprise strong winds are a top hazard for the Twin Cities, Waage said. If the type of derecho that devastated the Boundary Waters Canoe Area Wilderness in 1999, blowing down an estimated 25 million trees, hit the Twin Cities, he said, "it would be bedlam."

As it is, strong winds will cause about $35 million in damage every year in Hennepin County, according to the FEMA index, and about $10 million in Ramsey.

Blumenfeld said the storm system that roared out of South Dakota and raked across the Twin Cities in June 2013 "tore down more trees in Minneapolis than any other storm that we've clearly documented." They weren't even derecho winds, he said, but they struck after substantial rain had already soaked the ground and trees were "wobbling" in the soil.

Windstorms are the number one source of power outages in Minnesota, he said.

There's no evidence that climate change is amplifying the winds, he said. Warmer winters and heavier and more frequent precipitation remain the state's biggest climate change signals. But wetter soil means trees are more vulnerable to toppling, he said.

Waage noted that the FEMA index doesn't address all the types of flooding affecting Minnesota. It covers coastal and river flooding, but not flooding on regular ground caused by heavy rains and rising water tables.

"What we're finding is that nationally, about a quarter of flood damages are outside of flood plains now," Waage said.

Hennepin County's last federal flooding declaration in 2016, Waage noted, was not for a flood plain but for intense rainfall in Maple Grove and Brooklyn Park where water backed up on highways — so deep in places that motorists' air bags deployed when they hit it.