Joliet swamped by thundery 6+”cloudburst Thursday

The thunderstorm’s awesome rain-generating capacity was on display over parts of the Chicago area late Thursday, fueled by daytime heating and an enormous supply of moisture. The explosively unstable atmosphere produced by surging temperatures triggered the rainy storm clusters. While O’Hare and Oak Brook were teased with just a trace of rain, converging ground-level winds along a weak lake-breeze front across Kendall and Will Counties appeared to focus repetitive downpours on Joliet and Chicago’s southern suburbs. A lightning-punctuated cloudburst swamped one section of Joliet with 6.13" while a nearby weather observer measured 5.50" in only 90 minutes. Northern suburbs weren’t completely spared. Mundelein in Illinois’ Lake County was hit with 1.70".
Funnel clouds and tornadic wind circulations detected by Doppler radar prompted tornado warnings, though no touchdowns were confirmed by late evening.
-Tom Skilling