High Wind in Stephenson, Illinois

Thunderstorms developed north of a warm front in Missouri and raced northeast on a strong low level jet. A gravity wave developed off the thunderstorms in Eastern Iowa and Northwest Illinois and produced a concentrated band of high winds across Stephenson County Illinois. Official observation sites did not show this narrow band of high winds, but several home weather stations reported winds gusting over 55 mph before power was lost. The heaviest damage was in a 0.5 to 1 mile wide band running from about 2 miles south of Loran, Illinois to Freeport, Illinois. Numerous trees and power lines were downed with power poles snapped in half. A final report from Stephenson County Illinois ESDA indicated 1 barn, 1 shed, and 2 small metal sheds were destroyed, with dozens of trees downed. The high winds blew the HVAC system off the new county highway/EOC building, causing a roof fire when a gas line broke. About 2,000 people were without power with a majority of them in the City of Freeport.