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It looks like another round of thunderstorms will hit much of our area Wednesday with hot humid unstable air in place and an upper-air impulse 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 cool readings in the 60s and 70s along and inland of the lakefront versus highs in the middle 90s well inland triggered thunderstorms, a few of which were severe, dumping heavy flood-producing rains in excess of 2-inches at Aurora and Naperville and large hail – reaching half-dollar size north of Valparaiso.