The emergency sirens that warn of a possible tornado did not sound in Rogers before the twister hit around 10 Saturday night. In addition to the other damage, the F-2 storm caused a home to collapse, killing a 10-year-old girl. At least six other people were injured.
A tornado watch had been in effect for several hours that night, but there was no tornado warning. A watch means the conditions are right for a tornado. A warning means a tornado has been spotted or is visible on radar.
Rich Naistat of the National Weather Service says, in this case, there was no time to issue a warning.
"In this particular storm, the circulation on radar, which is one of the pieces of the puzzle that we use to diagnose the need for a tornado warning, occurred simultaneous with the touchdown. So one might say it was bad luck. This occurs in a minority of tornadoes, but it obviously occurred Saturday night," he said.
Ideally, the Weather Service raises a watch to a warning after a weather spotter has reported a funnel cloud, the rotation has shown up on radar or we're expecting or have received 75-mile-per-hour winds. Then the National Weather Service issues a warning and a recommendation that counties activate sirens in the effected area.
All tornado warnings come with recommendations for sirens. Naistat says in recent years the Weather Service has generally been successful with this process, but it's not 100 percent. He does say this is the first F-2 tornado in central and southern Minnesota since 2001 that was not preceded by a tornado warning. And Naistat says there was no reason to sound the sirens this time.
"I spent many hours this morning with some of my associates going over the radar imagery. It's very difficult to justify a decision other than the one made Saturday night," he said.
While counties generally wait for the National Weather Service for recommendations on sounding sirens, Tim Turnbull, the director of emergency preparedness for Hennepin County, says the county can activate sirens on its own in certain situations. "If we had a police officer or firefighter, somebody who'd been trained, a National Weather (Service) spotter, for example, and they go out when there are storms coming. If they'd seen something that would have indicated to us that the sirens should be set off, they would call Hennepin County dispatch and they would set the sirens off. And that did not happen," according to Turnbull.
And officials at the National Weather Service say if the same scenario happened again, they'd be hard pressed to change their response. Still, they're reviewing the actions taken on Saturday.
"It looks like everything we'd expect anyone to have done was done Saturday night and it still was not the optimum result," Rich Naistat says. "So we're going through this with a fine-toothed comb to see if we can find out that needle in the haystack that we still need to learn."
It may be little consolation to those who were hit by the tornado, but after the storm hit Rogers, Weather Service officials say a second storm moved through the area. A rotation cloud was spotted on radar. A warning was issued along with a recommendation to trigger sirens. The sirens went off, but there was no tornado that time.
Your support matters.
You make MPR News possible. Individual donations are behind the clarity in coverage from our reporters across the state, stories that connect us, and conversations that provide perspectives. Help ensure MPR remains a resource that brings Minnesotans together.