'The storm just tore across northern Wisconsin': When two weather fronts combine, it's a formula for disaster

Larry Parnass

The Berkshire Eagle

Though still standing, trees like these in the Chequamegon-Nicolet National Forest in northern Wisconsin are considered lost following a July 19 windstorm. They have little value as saw timber, given likely internal damage, rangers say.

LAKEWOOD - The ruinous July winds took shape when a line of thunderstorms moving east above Eau Claire caught up with a “rogue supercell” — a type of thunderstorm marked by rotating updrafts.

“Once they merged, bam!” said Eugene Brusky, science and operations officer with the National Weather Service in Green Bay. “The storm just tore across northern Wisconsin. All of a sudden it just took off.”

Radar shows the squall line thickening with the intensity of precipitation as it rakes past Rhinelander toward the eastern section of the Chequamegon-Nicolet National Forest. Experts call this kind of storm a derecho, after the Spanish word meaning “straight.”

From inside a cottage on Archibald Lake in Townsend, Rick Lemerond thought the roof was being peppered by hail. But when he came out, he found the storm was throwing something else at him.

“It wasn’t hail. It was acorns. A jillion acorns coming at you every which way,” he said.

The storm’s intense downdrafts raked forests, descending from elevations of a mile or so, then blasted horizontally at ground level with the direction of the advancing front.

Nearby on the same lake, trees and branches came crashing down outside a home hosting a family reunion. Eleven of 12 cars parked at the gathering were damaged, a town official said.

The weather service continues to study the storm, searching the damage captured by drone and satellite pictures for clues to what occurred.

“We’re trying to piece together the damage and extent of the storm. We’re just beginning that process now,” Brusky said.

Larry Parnass of The Berkshire Eagle in Massachusetts is examining forest health and forest management issues during a nine-month O’Brien Fellowship in Public Service Journalism at Marquette University’s Diederich College of Communication. Marquette University and administrators of the program played no role in the reporting, editing or presentation of this story.