Flash Flood — Morgan, Illinois

2011-06-17 to 2011-06-18 · near Meredosia, Morgan, Illinois

Event narrative

Flash flooding of historic proportions occurred in much of Morgan County from late in the evening of June 17th through much of June 18th. Rainfall amounts of 5.00 to 10.00 were reported, with the highest totals in east central Morgan County from Alexander to Franklin.

The nearly stationary thunderstorms produced a majority of the rain between 2200 LST and 0300 LST. The cities of Jacksonville and South Jacksonville recorded nearly 6.00 of rain in less than six hours, which was about 1.00 higher than a 100 year flood for that time period.

Nearly 2,500 homes, more than 100 businesses - including the Nestle Chocolate plant and many restaurants, MacMurrary College, and a state prison with more than 1,600 inmates sustained major flash flood damage. A levee for Mauvaise Terre Lake was overtopped at the Jacksonville Water Treatment Plant, destroying much of the equipment at the facility and shutting off the drinking water supply in Jacksonville for about three weeks until the equipment could be replaced and tested.

Several miles of Interstate 72 east and south of Jacksonville were closed due to high water during the morning of June 18th. Most streets in eastern and southern parts of Jacksonville were covered with several feet of water, and every rural road and highway in the eastern half of the county was water covered and closed.

Numerous people had to be rescued from their vehicles and at the Rolling Acres Mobile Estates mobile home park, however there were no reports of injuries or fatalities. Several pets, however, drowned due to the flooding at the mobile home park.

Property and business damages were estimated to be about $150 Million. There was no estimate available for crop damages in eastern Morgan County. The flash flooding continued as an areal flood for the same areas for at least another 40 hours, but the impacts of the flooding were felt for more than three weeks.

Wider weather episode

Thunderstorms initiated along an old outflow boundary extending from Jacksonville to near Lawrenceville during the evening of June 17th. Due to a strong low-level jet flowing into the area, the storms continually re-developed and tracked across the same locations, producing between 5 and 10 inches of rain across parts of Morgan and western Sangamon counties through the morning of June 18th. As a result, widespread flash flooding occurred from the Jacksonville area eastward to the Sangamon County border. Significant flash flooding also occurred in a large part of southeast Illinois where 3 to 9 inches of rain was reported. A few of the storms also produced gusty winds and small hail.

View location on OpenStreetMap → (39.8771, -90.5138)

Source: NOAA Storm Events Database, event_id 328509. Narrative written by the NWS forecast office that issued the report.