Flood in Massac County, Illinois

Water covered the roadway on the 2700 block of North Avenue and 1000 block of Country Club Road.

A 500mb shortwave trough moved across the Upper Midwest with height falls across the Quad State during the afternoon and evening of the 16th. The exit region of a strong (125kt) upper level jet was positioned across the area as well. Low-level winds strengthened during the afternoon to 50kts at 850mb. Following the early AM convection, ample sunshine allowed for a very unstable airmass to develop with CAPE of 3000-4000J/kg with deep layer shear of 65-70kts. Late afternoon, STP peaked at 9 near the Wabash/Ohio River confluence with effective SRH of 300-400m2/s2. Mid-level lapse rates peaked at 8-8.5C/km for much of the Quad State with significant hail parameter of 3-5 mid-afternoon and DCAPE peaking at 1200-1500J/kg. Initial storm formation was discrete with very large hail and tornadoes, with storms becoming more linear later in the evening with the approach of a cold front.

Damage reports were widespread near and south of IL-13 in Southern Illinois. An especially powerful supercell produced a violent tornado south of Marion with peak winds estimated at 190mph, the strongest in the Quad State region since the December 10, 2021 Western Kentucky tornado. The worst of the damage was between Andrew Rd and Wards Mill Rd with the EF-4 damage point a home swept off its foundation on Kyler Ct. This supercell would continue on to produce two more tornadoes (in Southeastern Saline and Southern Gallatin Counties) before crossing into Northwestern Kentucky. Large hail was commonplace with the afternoon supercells, with the largest reports being multiple baseball size hail reports in Pulaski County.