June 30, 2005: Straight-line wind across five counties

A small bowing squall line moved from northern Iowa across southern Wisconsin during the evening hours on June 29th into the early morning hours of June 30th. Large trees were knocked down with this bow echo across northern Iowa, Sauk, and Columbia counties before it weakened around 0000CST on the 30th. Spotter noted that the the gust front raced ahead of the storms, cutting off the inflow. Another line of storms developed behind the initial bow between 0100CST and 0200CST, and pushed across areas mainly north of Interstate 94. More large trees were toppled in Marquette, Columbia, Dane, Dodge, Jefferson, and Waukesha counties. As the second bow pushed east, it weakened, but still produced penny sized hail in Port Washington. Shortly after 0200CST, clusters of thunderstorms developed across Walworth and Rock counties and pushed into Waukesha, Milwaukee, Racine, and Kenosha counties between 0300CST and 0400CST. Scattered reports of toppled large trees were noted with this activity. Synoptically, a low pressure system tracked into northern Minnesota, dragging a cold front into southern Wisconsin. Warm, humid, and unstable conditions ahead of the system helped to produce severe thunderstorms despite the unfavorable time of day.