April 19, 2021

‘Tis the season for severe weather

National Weather Service brings awareness during ‘Severe Weather Awareness Week’ March 22 to 26

Saturday marked the first day of spring. As the change of season brings increased potential for severe weather, the National Weather Service is educating the public about tools and information that could keep them safe during Severe Weather Week, March 22 through 26.

“This is the time of year people need to start looking at that sort of thing and be prepared and make sure people have multiple weather sources to refer to,” said Byron Jimmerson, coordinator of Clarke County Emergency Management.

During a storm spotter training March 17, Chad Hahn, warning coordination meteorologist at the Des Moines Weather Service, said asked spotters to not rely so heavily on social media to relay information to the weather service.

“If you’re seeing a tornado out your window or from your house in the distance and you’re spotting that and you want to relay that information to us, it’s probably best not to do it on social media in hopes that we see that,” he said.

Instead, Hahn urged spotters to call 1-800-SKYWARN to report strong winds or tornado activity.

Those attending the training learned to report strong winds once they reach a minimum of 58 m.p.h. This level of strength is depicted by entire trees being in motion with twigs and branches coming off of them.

Risk levels for severe weather are rated from marginal to slight to enhanced to moderate to high depending on if the conditions assessed are favorable for storm activity.

“If you look historically for the state of Iowa, the majority of (high risk) days are slight-risk for us,” said Hahn.

However, Hahn pointed to cases where the threat level was underestimated.

“The Pella tornado day and the Marshalltown tornado day was a slight-risk day,” he said.

Hahn encouraged people to use the Wireless Emergency Alerts (WEA) app to be aware of potential weather-related threats coming their way. He also recommended apps that display radar to get a visual of where storms are coming.

Hahn said spotters need to identify updrafts and downdrafts when assessing the potential for storms.

“The air condenses and it forms a cloud in the updraft,” he said, “and the little droplets get larger, combine, freeze up above where it gets colder and it falls out as a downdraft.”

Hahn said with storm clouds, if there is dust or debris observed on the ground, visible features may not be present between the cloud base and the ground.

Hahn said that severe wall clouds tend to be bulky and visibly rising and indicate vertical rotation.

NWS does not have designated spotters, so the work of storm spotters is done at one’s own risk.

Hahn urged spotters to maintain situational awareness at all times.

“Always have an escape route,” he said. “Don’t jump in your car and go chasing, that’s not what we’re wanting folks to do.”

Hahn gave additional safety tips when driving during severe weather, such as staying away from spotting at night and that the vehicle frame will protect the driver when it is lightning out.

Spotters are encouraged to register at midiowaskywarn.org.

Clarke County will participate in a statewide tornado siren test 11 a.m. Wednesday. Weekly tests will begin at 9 a.m. Thursdays. Clarke County Emergency Management will also be sending out a social media blast to sign up for emergency alerts.