Boone County considers geographic zones for tornado sirens

Tuesday, July 16, 2013 | 12:01 a.m. CDT

COLUMBIA — When a tornado warning is issued anywhere within the 691 square miles of Boone County, all 80 sirens are activated. If strong rotation is seen on the radar or a funnel cloud is spotted in the Ashland area, for example, the sirens will also be triggered 35 miles away in Centralia.

Scott Olsen, Boone County's director of the Office of Emergency Management, is suggesting a change in the warning system to improve efficiency and address issues of siren desensitization. The solution would include a geographic zoning system that would only sound sirens in and near the immediate threat.

Jim Kramper, warning coordination meteorologist at the National Weather Service in St. Louis, said it's not unusual across Missouri for counties to sound sirens countywide and agreed there's a better approach.

“It’s this problem of, if there’s a warning, all of the sirens are activated even though there are bound to be parts of the county that aren’t affected," Kramper said.  

Since the May 2011 tornado in Joplin, Jasper County has made significant changes to its warning system with silent testing capabilities and a new zoning system. The county is divided into two zones: northern and southern, and based on the location of the threat, sirens can either be activated throughout the entire county or the affected zone.

Boone County is also in the process of upgrading its warning system, Olsen said, that will let emergency managers put a zone system into practice.

"The question becomes, how do you create a geographic zone that only activates certain sirens, and how do you do that very quickly on the fly?" Olsen said. "That's the biggest issue; I want to make sure that we don't have to take a lot of time to figure out what sirens to activate."

As it stands, a single button is pushed to alert all of Boone County of a tornado threat. Olsen worries the extra time it could take to determine the affected area and find the corresponding sirens could threaten the safety of the public.

"We need to come up with a solution, it's just figuring out which is going to be the best solution," Olsen said. 

The National Weather Service issues tornado and other severe weather warnings for specific areas in the path of a storm. Specific geographic zones would help the sirens correspond more closely to the warnings issued by the weather service. 

The zones being considered for Boone County are north, central and south, Olsen said. That way, if there is a threat in Columbia, Ashland wouldn't need to know. 

Silently testing the sirens

Jasper County has adopted a silent testing system, which enables it to decrease the number of times the sirens are sounded for tests.

"The National Weather Service's survey after the May 22, 2011, tornado found that many citizens had become desensitized due to their being tested weekly," said Keith Stammer, director of the office of emergency management for Joplin and Jasper County. "Now we only audibly test them once a month."

The silent test allows the sirens to be tested every morning, reducing the number of times the sirens are heard for tests from 48 times per year to 12.

But Olsen has reservations about silent testing in Boone County.

"The only thing that concerns me is there's no way to know if it really works until you sound the siren," Olsen said. 

Stammer had nothing but praise for the new technology.

"The silent test has been pretty effective all the way around," he said. "After a thunderstorm, I can just get online and test the sirens and see if lightning got any of them, and as soon as the sun comes up, I can send someone out to fix it."

The only analysis the silent test can't evaluate is battery life, which is checked during the audible tests every month. With the upgrades, solar panels were installed on each siren that can charge the battery in case a landline fails, Stammer said. 

A better option for monthly testing might include coordinating monthly testing of all sirens on the same day in Audrain, Boone, Camden, Callaway, Cole, Cooper, Gasconade, Howard, Miller, Montgomery, Morgan and Osage counties.

When to sound the sirens

Each county holds its own protocol for dealing with severe weather based on certain criteria, Kramper from the weather service said. Some counties activate sirens — even without the threat of a tornado — if there is the possibility for extensive damage such as strong winds or large hail.

"They figure that's going to cause damage and people need to get inside, and that's fine, as long as they make it known," Kramper said. "They need to tell their citizens that this is what they're doing." 

Jasper County activates its storm sirens for tornadoes as well as storms capable of producing high wind speeds.

In Callaway County, emergency management director Michelle Kidwell has put a policy in place only allowing sirens to be sounded when there is a tornado warning. Although Callaway County also sounds the sirens countywide, its mass notification system is specific to the area directly affected by the threat. Residents sign up to receive notifications through email, text message or phone call. 

In Boone County, according to the Office of Emergency Management website, sirens can be activated because of severe weather and other types of emergencies including chemical incidents. Olsen said there has been discussion about restricting siren usage to tornadic events and developing a specific plan that outlines the parameters for when sirens are sounded.

What's next?

Olsen has been looking at studies regarding desensitization and talking with the county's siren maintenance contractor to determine the best option for Boone County. The recommendation will be to implement three broad zones — north, central and south — to improve the overall efficiency of the storm warning system.

In Columbia, the call will be made by the City Council.

"Ultimately, the council speaks for the city of Columbia," Olsen said. "They could choose to make a certain decision on their own, but I hope they'd look at the information we present and what our decision is."

 Supervising editor is John Schneller

Like what you see here? Become a member.

Show Me the Errors (What's this?)

Report corrections or additions here. Leave comments below here.

You must be logged in to participate in the Show Me the Errors contest.


Leave a comment

Speak up and join the conversation! Make sure to follow the guidelines outlined below and register with our site. You must be logged in to comment. (Our full comment policy is here.)

  • Don't use obscene, profane or vulgar language.
  • Don't use language that makes personal attacks on fellow commenters or discriminates based on race, religion, gender or ethnicity.
  • Use your real first and last name when registering on the website. It will be published with every comment. (Read why we ask for that here.)
  • Don’t solicit or promote businesses.

We are not able to monitor every comment that comes through. If you see something objectionable, please click the "Report comment" link.

You must be logged in to comment.

Forget your password?

Don't have an account? Register here.