It looks like another round of thunderstorms will hit much of our area Wednesday, with hot, humid and unstable air set to trigger strong to severe storms mainly later in the afternoon and overnight.
Tuesday saw very warm, rather humid air initially positioned overhead, but a combination of outflow from earlier thunderstorms over southern Wisconsin and a “back-door” cold front moving south along the Lake Michigan shoreline set up a strong on-shore easterly flow that carried well inland. This strong “frontal” boundary with a 30-degree temperature differential between readings in the 60s and 70s along and inland of the lakefront versus highs in the mid-90s well inland triggered thunderstorms, a few of which were severe. Heavy, flood-producing rains dumped more than 2 inches at Aurora and Naperville and large hail — reaching half-dollar size — north of Valparaiso.
