EF1 tornado in Jefferson County, Illinois

A cell merger led to a brief tornado along IL Hwy 37. Two metal buildings had much of their roofs removed, bay doors blown out, and large portions of walls removed. Several buses inside sustained significant damage from debris with 6 out of 14 buses totaled. Building material was pulverized and embedded in the ground and adjacent walls downstream of the start of the damage with other debris wrapped around nearby trees, fences, and powerlines. A nearby metal building sustained roof damage. Trees were uprooted and snapped near the start and end of the path. Peak winds were estimated near 90 mph.

A cold front, which stretched from Oklahoma to Central Illinois over to Northern Ohio, progressed slowly through the Quad State region, with an MCS moving through during the evening hours. An early afternoon SGF sounding placed MLCAPE at around 2000 J/kg. Deep layer shear was 50-55 kts with 0-1 km shear of 30 kts with 200 m2/s2 SRH. In Southern Illinois, there were two lines that developed. The southern line had a more SW to NE orientation further south and was weaker than portions further south in SE Missouri and far W Kentucky. The northern line had a more west to east orientation near the I-64 corridor and was much more active. Jefferson County in particular had severe damaging wind reports, large hail, and a brief EF-1 tornado north of Mount Vernon which did significant damage to a bus depot and several of the buses inside. A microburst developed just east of that tornado, scattering debris from a metal building system. A second EF-1 tornado occurred in Wayne County northeast of Fairfield, snapping many pine trees, and causing a mobile home to lean over. Additional wind damage reports were received along the I-64 corridor.