Thunderstorm Wind — Johnson, Illinois

2024-05-26 · near Vienna, Johnson, Illinois

Event narrative

A roof was blown off of a shed as a thunderstorm moved through the area.

Wider weather episode

The second major severe weather outbreak for the month occurred on the 26th for the Quad State region. On the synoptic scale, a shortwave trough centered in the middle of the country with a 60 kt mid-level jet moved across northern Arkansas. A weak surface low was moving into SE Missouri during the morning with a secondary low located further northwest. A warm frontal boundary was draped across our area. A bowing line progressed east across SE Missouri into W Kentucky and far S Illinois between 0500-1000CST, followed by a mostly sub-severe second line that exited the region by 1300CST. The environment recovered producing fuel for more severe storms, starting with supercells 1800-2100CST with a line of storms moving east-southeastward across the entire Quad State after 1900CST, crossing through by midnight. Across the Quad State, this event produced the record for most tornado track miles in a single day in office history, along with the second most warnings issued in a day (just behind the May 8, 2024 event). Widespread straight-line wind and tornado damage resulted in over 100,000 customers without power across the Quad State.

For the morning, MLCAPE values at 0700CST were 1000-1500 J/kg in S Illinois. Effective bulk shear was 40-50 kts with STP of 1. Precipitable water was 1.5-1.75 in. The morning storms mostly missed just south of S Illinois with some street flooding in Johnston City.

Heading into the evening, MLCAPE values at 1800CST were 2000-3500 J/kg in S Illinois. For S Illinois, effective bulk shear rose to 50 kts, with SRH around 150-250 m2/s2 and STP of 2-3.5. 0-1 km shear was 20 kts. Mid-level lapse rates were 7-7.5 C/km. DCAPE of 1200-1400 J/kg provided ample opportunity for downburst winds.

Three tornadoes occurred in S Illinois. Two of these were with the late afternoon to early evening supercells. An EF-3 in the Lake of Egypt area of Johnson County debarked some trees, damaged several homes in the Eagle Point Bay subdivision, and injured one person. An EF-1 tornado in Johnson and Union Counties ahead of the approaching cold front tracked southeastward to Buncombe. The third tornado, an EF-1, was with the cold front in the Grayville area, tracking into Gibson County, IN. The supercells produced several hail reports, with a 2 inch hail report near the Williamson/Saline County border. Training heavy rain produced significant flash flooding for the second time in a month in Saline County, focused on Harrisburg with U.S. 45 flooded and at least one water rescue. Rainfall amounts in Southern Illinois were 1-4 inches, with the highest amounts in Alexander/Pulaski County and along a line from Williamson to Gallatin County. Numerous trees and power lines were damaged with the supercells and the frontal passage. Late evening power outages amounted to roughly a third of Williamson, Union, Johnson, and Alexander Counties.

View location on OpenStreetMap → (37.4100, -88.8900)

Source: NOAA Storm Events Database, event_id 1185503. Narrative written by the NWS forecast office that issued the report.