(11:45AM - 6/19/21) Multiple disturbances will continue to move through the region through tonight, bringing periods of severe t'storm potential to portions of the state through tonight.
Multiple disturbances will continue to eject out of the Plains, and push eastward across the Midwest and Great Lakes through tonight. These disturbances will bring periods of severe t'storm potential to portions of the state, through tonight. With this update...Little to no change was needed for the forecast for today-tonight.
Another disturbance set to move through the area today, and there is frontal boundary slowly pushing southward across the state, and an outflow boundary in place across Western and Southwestern Illinois. All of this will provide focus for scattered shower and t'storms development this afternoon across portions of Western and Southwestern Illinois. This activity will spread southeastward across portions of Central and Southern Illinois, this afternoon through late tonight. An environment supportive of a severe t'storm threat will be in place. This environment will feature moderate to high instability of 3,000-5,000J/KG, dew points in the mid 60's to low 70's, good shear, good forcing, and high lapse rates of 6.0-7.5C. This environment will be supportive of upwards of a an isolated severe t'storm risk (level 1) across the heart of the state, and a widely scattered severe t'storm risk (level 2) across portions of Southwest and Southern Illinois.. Damaging winds and hail will be the main severe weather threats, though an isolated tornado cannot be ruled out.
Below is the severe t'storm forecasts for this event.
Thursday Evening-Friday Morning...
A large complex of rain and t'storms developed across Western Wisconsin, Southern Minnesota and Northern Iowa Thursday evening. This complex featured numerous severe t'storms Thursday evening and early Thursday night across Western and Central Wisconsin and Southern Minnesota. This complex then pushed southeastward across Central and Southern Wisconsin, Northern Illinois, Northern Indiana and Southern Michigan, Thursday night into Friday early morning. While there were no severe t'storms that occurred while traversing Northern Illinois with this complex Thursday night and early Friday morning, some areas received strong non-severe winds of 45-55MPH, including across the Chicago metro area.
Friday Afternoon-Early Saturday Morning...
A few isolated severe t'storms occurred Friday afternoon and evening across portions of Central Illinois, but the main focus was Friday night. Scattered severe t'storms developed early Friday night across Southern Iowa into Western Illinois. This activity grew upscale into a large complex, which pushed southeastward across the heart of the state Friday night into early Saturday morning. Some of these t'storms were severe, producing damaging winds, large hail and potentially an isolated tornado southeast of Galesburg.