As tech evolves for severe weather warnings, Hennepin County leads the way

Hennepin County emergency managers are scrambling to gain an edge on global climate change, embracing a host of new technologies to track tornadoes, floods and icy conditions to better alert residents when dangerous weather is looming.

Hennepin County staffers use an array of new equipment to evaluate stormy weather in real time and collect data for research to prevent damage, injuries and death.

"We used to just look at past weather statistics and said that's the way it will be," said Hennepin County Emergency Management Director Eric Waage. "But future weather history will go down roads that have not been traveled down."

Hennepin County, the largest in Minnesota, is emerging as a national leader in analyzing dangerous weather events and expanding the technology beyond merely relaying warnings from the National Weather Service.

The county has installed several dozen highly sensitive monitoring sites, called Mesonets, that measure wind speed, rainfall amounts, soil moisture and temperatures, ice conditions, lightning and radiation. The sensors are placed on a pole and surrounded by a 40- by 40-foot fence.

Hennepin County weather officials developed a statewide manual for counties to activate siren warnings, and the county employs full-time meteorologists and a climatologist. County weather officials also are buying sophisticated software that will allow them to sound a siren for a specific section of a city depending on the threat.

The county spent about $3 million in 2020 on its emergency management operation.

Tracking the effect of weather on public safety, and on people's health and well-being, is a major objective of the county's expansive climate action plan, which the board is expected to approve next month. The plan lays out dozens of directives, such as increasing the number of weather-monitoring stations and identifying flood risk areas.

Regarding climate change, Waage said, the operating theory is that the atmosphere is becoming more volatile. When it becomes hotter, it holds greater moisture that adds to the volatility mix, he said.

The county has already completed several studies on weather damage. One study examined landslides and mapped areas where it is unsafe to build. The metro area had two significant landslides, which killed several children in St. Paul and closed W. River Road for several years. The next study will address rising water tables.

The wailing siren came long before the new technology and the amplified climate change concerns. Hennepin County has nearly 300 sirens, some of which are decades old. The county controls siren activation, but each city is responsible for maintenance and testing. Most people are familiar with the monthly siren tests, but cities also do brief tests at a lower volume several times a month.

Hennepin became one of the first counties to use sirens for weather alerts instead of as a civil defense tool to warn residents of an impending attack during World War II. The shift came after tornadoes devastated Fridley and surrounding areas in 1965. Back then, the sirens had to sound throughout the entire county.

Cities have also changed the power source for sirens, Waage said. Sirens were powered by an area's electrical grid, but now cities use a combination of electricity and solar energy. Almost all sirens have a backup battery that allows them to run for an hour.

Ramsey County, the smallest geographical county in the state, has about 100 sirens. All the sirens were replaced about five years ago due to age, said Judd Freed, the county's director of emergency management and homeland security.

Ramsey County's size makes it impractical to buy Mesonet sensors, which cost about $12,000, like Hennepin County did, he said. Instead, Ramsey County has a new radio system to activate sirens and has been installing software that will allow staff to target a more specific area of a city if a warning is needed.

"We do risk profiles to examine the future of climate in Minnesota," Freed said. "We were terrified of last year's prediction of major flooding, but the weather moderated and it didn't happen. Climate change makes for an ever more complex world."

Hennepin County controls sirens from an emergency management building in Medina, where the county also has a Mesonet sensor. The equipment helped the county trigger a warning for softball-sized hail that pelted the western part of the county last year, Waage said. The National Weather Service lacked the ability to warn for hail, he said.

"We issue warnings for tornadoes, flash flooding, severe thunderstorms and strong winds," said Todd Krause, warning coordination meteorologist for the National Weather Service in Chanhassen. "With Mesonet, Hennepin has helped us determine whether to issue warnings for damaging high winds."

The Minneapolis-St. Paul International Airport has also benefited from Hennepin County's Mesonet system. It is the only airport in the United States to have a sensor, which helps collect data about freezing rain and ground temperatures to determine if chemicals are needed on runways, said Kristin Rollwagen, the airport's emergency programs manager. Flying Cloud Airport in Eden Prairie is in the process of getting a sensor.

MSP airport has three sirens and the authority to send emergency warnings to travelers' cellphones.

Hennepin is considered a leader in weather warning and sensor systems, Waage said. Other states, including Iowa, adopted the state's policy on recommended siren activation. The military has also asked for data collected by sensors, he said.

Even with all the cutting-edge technology, Hennepin County sounds the sirens only about twice a year.

"If you do hear a siren, get inside and get information," said Waage. "We are just trying to make things more accurate and timely for people."

David Chanen • 612-673-4465