Flash Flood — Sangamon, Illinois

2011-06-17 to 2011-06-18 · near Berlin, Sangamon, Illinois

Event narrative

Flash flooding of historic proportions occurred in western Sangamon County from late in the evening of June 17th through much of June 18th. Rainfall amounts of 5.00 to 9.00 were reported, with the highest totals along the boder with Morgan County. The nearly stationary thunderstorms produced a majority of the rain between 2200 LST and 0300 LST.

Every rural road and state highway in western Sangamon County was water covered and closed. Streets and about 300 homes in the towns of New Berlin and Loami, as well as numerous farms in west central parts of the county, were severely flooded. Around 22,000 acres of farmland also sustained significant flooding.

Property and business damages were estimated to be about $3 Million, while crop losses could be close to $10 Million. The flash flooding continued as an areal flood for the same areas for at least another 20 hours.

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 → (39.7854, -89.9885)

Source: NOAA Storm Events Database, event_id 328579. Narrative written by the NWS forecast office that issued the report.