Residents of Missouri and adjacent portions of Illinois sweltered in triple-digit heat and excessively high humidity on Friday. The northern fringe of this tropical air mass became explosively unstable across Iowa and northern Illinois, resulting in an outbreak of severe thunderstorms. Radar showed that thunderstorm updrafts towered to 60,000 feet, producing half dollar-sized hail, damaging winds, and torrential rains. Tornadoes were also reported northeast of the Quad Cities, and near Chebanse, in Iroquois county. Though overnight storms have stabilized the air, sufficient heat and humidity are to remain across the area through Saturday. Scattered thunderstorms are expected to develop again during the afternoon. The Storm Prediction Center has highlighted much of the metro area to have a slight risk of severe thunderstorms.