Public reminded of storm siren procedures

Solid tone alerts citizens outdoors; there’s no ‘all-clear’ signal

John Corn

By Conrad Dudderar
Staff Writer

The City of Yukon operates nine outdoor warning systems inside Yukon city limits.

These are often referred to as “storm sirens” or “tornado sirens.”

Yukon Police Chief John Corn wears another hat, that of emergency management director.

“It’s not uncommon to see tornadic activity – even into July,” Corn said. “We had storms created flash flooding issues impacting the lake.

“The heat index was off the chart in recent days, and that can create its own public health crisis when people go outside, for recreation or work, and get overheated.”

With input from the City of Yukon’s emergency management team, Chief Corn decides when to sound those sirens to alert Yukon residents who are outside of impending tornadoes or other severe weather.

“If severe weather is within an hour of the city, we are now under a full watch and are monitoring that for the period,” Corn said. “We can determine if it’s going to track, if we’re going to be affected or if it’s going to go around us.”

A problematic issue arose when the National Weather Service would set off Yukon’s outdoor sirens automatically upon announcing a severe thunderstorm warning for Canadian County.

But that didn’t necessarily mean Yukon was in danger’s path.

“The polygon we are using to track a storm isn’t the same when the National Weather Service (NWS) puts Canadian County in a tornado warning or severe thunderstorm warning,” Corn explained. “It could be the north part of the county; it could be the south part of the county. But they don’t specify that. The whole county goes ‘hot’.

“We’ve had sirens go off when the sun was shining, and we were not in an imminent threat or danger of anything happening here.”

Yukon Emergency Management officials took the outdoor warning system off the automatic NWS activation, and that has eliminated confusion among residents.

“If you’re going to have an outdoor warning system to alert people who are active outside, are in the park or maybe shopping – if you set them off all the time, people get to be desensitized,” Corn reasoned. “Then they don’t pay attention, especially when they’re going off when it’s 75-80 degrees and the sun’s out.

“It may be a severe supercell coming into the south part of the county, and it’s not going to make it to us. It may get Mustang, but our residents would never know that.”

That’s why the City of Yukon doesn’t sound the sirens unless the city is in the direct path of a tornado or severe storm.

In 2011, Yukon and most other metro cities followed Oklahoma City’s lead by installing an outdoor warning system upgrade.

“We had converted our system from the old civil defense sirens to the new Whelen self-contained enclosures,” Corn said.

Yukon’s emergency management team consists of Chief Corn, City Manager Tammy Kretchmar, Assistant City Manager Mitchell Hort, Fire Chief Shawn Vogt, and Public Works Director Arnold Adams.

Before severe weather strikes, city officials are inside Yukon’s Emergency Operations Center at the police station monitoring live radar, the National Weather Service and local weather forecasters.

“If we monitored (a severe storm) for 30 minutes and established a decent track and it’s within 30 minutes of the city, then we’re going to sound those sirens,” Corn said.

“If someone is out shopping at a store or is driving on the roadway heading home, anything less than 30 minutes isn’t adequate time to get to a safe place or shelter – and out of a vehicle.”

But time is not always a luxury because a storm cell may develop and become tornadic very quickly in the Yukon area.



There was concern in the late 2000s and early 2010s about what different tones meant when the sirens were sounded.

“It became confusing for residents,” Corn pointed out. “The area emergency managers at that time got together and developed a standard warning tone for tornadoes and inclement weather.”

The tone is a three-minute, constant burst. It is a solid tone, with no high or low.

Yukon residents hear this tone when sirens are tested at noon on Saturdays.

These tones are heard whenever the threat of a tornado or other severe weather event is approaching or occurring.

“As long as that storm system is coming and we know we’re imminent, we’ll sound them,” Corn said. “We will continue to sound them after every three-minute burst until that moves away.”

Every jurisdiction has a slightly different threshold when deciding whether to sound their outdoor warning system.

Yukon never had to activate its sirens during a severe thunderstorm, typically only doing so for tornadoes.

Some other cities activate their sirens under a severe thunderstorm warning, if the wind speed exceeds 70 miles per hour and/or the hail size is more than one inch.

“That is large enough it will bust glass,” Yukon’s emergency manager explained. “If a one-inch hail stone hits a person outside, it could seriously injure them if not kill them.”

The Yukon Police Department does receive complaints from residents who say they don’t hear the sirens inside their homes because they were watching TV.

“That’s what they are called an outdoor warning system,” Corn emphasized. “They are not designed to alert you if you’re in your house.”

The public is advised not to rely solely on hearing the outdoor sirens to stay updated about approaching storms.

“If it’s imminent and it’s coming, most of your local broadcast stations are already all tracking,” Corn said. “Their local media is as good an outlet for information about what’s coming, what’s going to happen and what to expect.

“They are good at tracking and giving you an estimated time of arrival. You can tune into your local station and get that track and get a timeline.”

These details help Yukon residents determine whether they want to get inside their storm shelter or safe room.



Chief Corn was recently contacted by a citizen who said they never heard an “all-clear” signal after Yukon’s sirens were sounded.

“When the emergency managers came up with their tone protocol and their tone sound, at that time the all-clear was becoming a confusion point,” he pointed out.

“People would hear the sirens and went to their cellars, then they heard what used to be three airhorn bursts. Back in ’08 and earlier, that was the all-clear. It started confusing people that had just moved in and weren’t familiar with Oklahoma.”

So, the area’s emergency managers decided to do away with the all-clear signal for storm sirens.

“Jurisdictions do not use an all-clear sound anymore,” Corn emphasized. “You could have nine to 12 minutes of sirens as that storm moves past. That’s a pretty good threshold because a tornado doesn’t sit and hold over you like a thunderstorm does.

“If it develops, it’s moving at a pretty good pace. In six to eight minutes, it will clear the city jurisdiction.”

The Federal Emergency Management Agency (FEMA) recommends people enroll in an electronic notification system while relying on local and national media outlets to determine when a storm is approaching and has passed.

Yukon Police will start pushing out pre-alerts about flash flooding, tornadoes and other severe weather on its social media platforms. Emergency management information also is posted on the YPD Facebook page.

Yukon residents also are encouraged to enroll in the Regroup mass notification system through a link on the City of Yukon’s website (under Police Department and Emergency Management).

This allows them to be contacted automatically by email or phone with message alerts – such as flash flooding, city office and road closings or an active shooter situation.

“We can reach people through an electronic notification – and can do it so much faster,” Corn said.