(3:00PM - 8/24/21) Multiple disturbances moving through the region will bring severe t'storm potential to portions of the state, through tonight.
Several disturbances are moving through the Plains, Midwest and Great Lakes, along the northern edge of ridge in place across the Central and Eastern US. These disturbances will aide in bringing severe t'storm potential to portions of the state, through tonight.
This Afternoon - Tonight, Aug 24th...
While the threat for severe t'storms for today previously looked very low, things have taken a quick turn, with severe t'storm risk looking more likely across Northern Illinois for this afternoon into tonight. A few complexes of rain and t'storms have been moving across Minnesota and Wisconsin this morning and this afternoon. An outflow boundary associated with these complexes has been moving southward across Southern Wisconsin, and will settle into far Northern Illinois this afternoon and evening. This outflow boundary will provide focus for isolated to scattered shower and t'storm development this afternoon and evening, with an isolated severe t'storm risk being possible. With that all said, the main focus will be for later this afternoon into early tonight, as a complex of severe t'storms has developed across Northern Iowa is expected to sweep east-southeastward across Southern Wisconsin and Northern Illinois. As this complex moves across the aforementioned areas, an environment will be in place supportive of a severe t'storm risk with this activity. This environment will feature high instability of 3,000-5,500J/KG, dew points in the low to upper 70's, modest shear, modest forcing, and good lapse rates of 6.5-7.5C. This environment will be supportive of upwards of an isolated to scattered severe t'storm risk (levels 1-3) across portions of Northern Illinois. Damaging winds and hail will be the severe weather threats, though an isolated tornado can't be ruled out.
Below are the severe t'storm forecasts for this event.