Thunderstorm Wind in Pulaski County, Illinois

Damaging winds crossed parts of Pulaski County, downing numerous trees. A 48-year-old woman was killed when a tree fell onto her car as she was driving on Old U.S. Highway 51 about two miles south of Ullin. At Mounds, a teenage girl was seriously injured when a tree fell on her in a city park.

A severe weather outbreak occurred during the afternoon and early evening hours. An organized line of severe thunderstorms formed over the central Plains states during the night of the 20th. This bowing line of storms progressed southeast across the St. Louis area during the midday hours, then down across the lower Ohio Valley and southeast Missouri during the afternoon. Widespread wind damage was reported in parts of southern Illinois, especially in far southern areas from the Marion-Carbondale area southward to the Ohio River. Flash flooding was reported in a few locations. The atmosphere ahead of the storms became strongly unstable, with surface-based capes exceeding 4,000. Given the strong buoyancy, wind profiles were sufficiently strong for widespread severe weather. Deep-layer (0-6 km) wind shear values were no higher than about 30 knots, and 0-1 km shear was about 20 knots. Even though the region was under a broad 500 mb ridge, a moderately strong low-level feed of very moist and unstable air fueled the intense storms as they propagated southeastward.