The system to activate warning sirens in Washington County stopped working in the middle of Sunday's severe weather, leaving areas of the county without any siren warnings and vividly highlighting the difficulties faced by local governments in providing tornado warnings.
There is no state law or state agency that monitors sirens, whether they're activated or even if they're kept in working order. The federal government doesn't have any local or state requirements for sirens, which are owned and operated nationwide by individual cities, counties, and private entities.
In fact, the presence, oversight and maintenance of sirens vary greatly by county throughout Minnesota. Ramsey, Anoka and Hennepin counties, for example, contract with a company that tests the sirens electronically on an almost daily basis. Other counties conduct their own testing. But some counties don't have any sirens and rely on weather radios instead.
"The bottom line is whoever owns the sirens decided the policy," said Todd Krause, a warning coordination meteorologist with the National Weather Service. "If they own it, they decide when and where and how. You'd have to have Minnesota owning every single siren in the state to dictate something like that."
Krause said many people also don't understand the purpose of sirens. Cities in Minnesota, like those in other states, installed the sirens for civil defense after World War II. The sirens were meant to signal a nuclear strike. But when powerful tornadoes swept across the Twin Cities in 1965, the cities used the sirens to alert residents.
Those tornadoes left 13 people dead and 683 injured. Sirens have been used for severe weather ever since, although they could still be used for civil defense or other emergencies.
On Sunday, the National Weather Service issued a tornado warning for Washington, Anoka and Ramsey counties at 2:45 p.m.
In Washington County, the communications center immediately received the warning from the National Weather Service through an electronic system. The dispatchers then activated equipment in a privately-owned tower in Stillwater. The equipment, which is owned by the county, sends out a tone that activates the individual sirens.
Sirens in Oakdale sounded, but a short while later, the equipment in the Stillwater tower lost power. That meant it was unable to activate the rest of the sirens.
The county doesn't have a system in place to alert it if the tower equipment loses power. They found out when Forest Lake police officers called the county 10 minutes after the tornado warning was issued, to say that the sirens weren't sounding.
“Unfortunately, the sirens were not designed to be heard indoors. You can't be solely reliant upon that.”Diane Cooper, National Weather Service
The county unsuccessfully tried to activate the equipment again. They eventually used equipment in a backup tower and were able to get the sirens to sound at 3:23 p.m. -- 38 minutes after the first tornado warning. By that time, the tornadoes had already passed. The tornado warning expired at 3:45 p.m.
Dan Starry, the chief deputy of the Washington County Sheriff's Office, said that no one in Washington County was injured in the storm. The storm killed one person in Minneapolis and injured dozens.
The county plans to test its equipment Wednesday to determine what caused the problem. Starry said the county tests the equipment every month and hasn't had any malfunctions. He said the problem could be due to a power surge or lightning strike.
"This was kind of a fluke," said Deb Paige, the director of emergency management for Washington County. "Every form of technology can go wrong, and that's why we tell people to have more than one form of alert."
County officials declined to name the companies that made and sold the malfunctioning equipment. Paige said Xcel Energy owns the tower that stores the equipment. She stressed that the county-owned equipment failed, not the tower. An Xcel Energy spokesperson was not able to immediately confirm that it owns the structure.
Paige said the equipment functioned when tested on April 6, April 14, and May 4. She said the monthly tests will sometimes uncover problems with a siren, and then the city that owns the siren will fix it.
Washington County has 74 sirens, all owned by individual cities. The cities are responsible for maintaining them, but the county is responsible for sending out the tone that activates them.
Other counties have experienced problems with sirens during storms as well. Ten emergency warning sirens failed to sound in Rochester when a tornado struck on June 17, 2010. No one in the town was injured. A month later, 18 warning sirens in Red Wing failed to sound as a severe thunderstorm swept across the area.
Diane Cooper, a service hydrologist with the National Weather Service in Chanhassen, said the problems in Washington County show how important it is for residents to have a weather radio, and not relying on a patchwork of city and county alerts.
A weather radio receives instant updates from the National Weather Service. If the agency issues a tornado warning, it only takes a few seconds for the weather radio to sound an alert.
Cooper said people should consider weather radios to be as important as smoke detectors. She points out that sirens are meant to provide warning for people who are outside, and possibly away from radio or other forms of communication.
"Unfortunately, the sirens were not designed to be heard indoors," she said. "If you happen to hear them indoors, that's great. That's another piece of information that you can use to help keep you aware. But you can't be solely reliant upon that, either."
Washington County officials said they are considering purchasing an alarm system to let them know when their equipment loses power. And they said they're talking with several vendors who provide siren-related equipment to rule out other causes of the malfunction.