Aug 21, 2021
A subtle upper-level shortwave associated with a cold front, draped across the county warning area, was advancing southeast, aiding widely scattered convection to develop ahead of the front in western Illinois. While instability was sufficient to support modest storms, a considerable lack of deep-layer shear and weak low-level lapse rates kept these cells far from severe strength. However, a few slower storms were producing very robust rainfall rates (nearly 2.00/hr) in southwest Illinois amidst
Source: NOAA National Weather Service Storm Events Database (event 980047). Narrative written by NWS staff at the time of the event.
This event is one of many recorded floods in Marion County. See the full FEMA flood zone map, NFIP claim totals, and disaster history for the area.