For decades, WUWM assistant director of programming Lauri Jones has driven through Walworth County on her way to visit her parents in Illinois.
Over the years, she started noticing something.
It seemed like Walworth County was always getting hit by severe weather: heavy snow, rain, ice, or storms.
"Is it true, or is it just my imagination?” Jones wondered. “Is there something going on with Walworth County where they get hit hardest?”
She sent her question to Bubbler Talk, and we took it to Tim Halbach, a meteorologist with the National Weather Service in Sullivan, Wisconsin.
It starts with location
Halbach says there is some truth behind Jones’ observation. Walworth County sits along Wisconsin’s southern border, where warmer and more unstable air is more common than in northern parts of the state. That can create more opportunities for severe storms.
“If you looked at Walworth County versus somewhere way up north, like Iron County, they’re cooler more often,” Halbach says. “They don't get the highly explosive, more unstable-type air masses as frequently as in a county like Walworth.”
But there’s another factor that might be more surprising: Lake Michigan. Walworth County doesn’t border Lake Michigan. But that doesn’t mean the lake has no influence on its weather.
How can Lake Michigan affect Walworth County?
When the land warms faster than the lake, cooler air can move inland from Lake Michigan, creating what meteorologists call a lake-breeze boundary.
That boundary can travel well beyond the lake’s shoreline. Sometimes, it can reach Walworth County. And when a thunderstorm encounters that boundary, it can change the storm’s behavior.
"There’s a boundary of the lake breeze that will come through that can actually help enhance severe weather sometimes if a storm hits that boundary,” Halbach says. “It can change the storm.”
The lake-breeze boundary can provide an additional source of lift and instability. Under the right conditions, it can also contribute to rotation in developing storms.
“That can be a source for where these storms take off and have a little bit extra spin with them,” Halbach says.
Jones says she didn’t expect Lake Michigan to play a role.
“I didn't think that Lake Michigan would have anything to do with Walworth County because it's so far away,” she says.
Lake Michigan’s influence isn’t limited to thunderstorms.
The lake can also contribute to winter weather when winds and temperatures line up in the right way.
Halbach remembers one ice storm in which Walworth, Kenosha and Racine counties saw particularly high ice accumulations.
Is Walworth County actually a storm magnet?
There’s another factor to consider: Walworth County is relatively large.
That means it covers more land where a storm can occur.
Part of it is that it’s a bigger county, so that’s a bigger target for stuff to happen,” Halbach says.
There’s also the way people remember extreme weather. A particularly damaging storm can stick with us, making it feel like severe weather happens more often than it actually does. It's called recency bias.
But Halbach says long-term tornado data does show a pattern.
“If you look at the full database of tornadoes that have happened, it’s more frequent down in southern Wisconsin, and particularly Walworth County,” he says.
So, Jones’ hunch was on to something.
Severe weather has real consequences
Halbach doesn’t just study storms from behind a computer. He also helps survey tornado damage after severe weather events. That means he sometimes sees the aftermath firsthand.
Halbach was working the morning of a July incident on Geneva Lake in which three children died after a boat accident during severe winds.
“With the recency of the Lake Geneva boat accident with the severe winds that came through that day, I was working that morning when those storms came through,” Halbach says. "Anytime that there’s a loss of life or anybody gets injured or there’s widespread damage, you’re always kind of left with like, 'what else could we do to help out?'”
So, why Walworth County?
Walworth County isn’t necessarily cursed with severe weather. But several factors can make it more vulnerable to certain types of storms. Its location in southern Wisconsin puts it in an environment where warm, unstable air is more common. Lake Michigan can sometimes add another ingredient through its lake-breeze boundary. And because Walworth County is large, there is simply more land for storms to cross.
As Jones puts it: “Location, location, location, and the size of the county.”
So, if it feels like Walworth County keeps getting hit by the next big storm, there’s more to the story than coincidence.
_
