(10:00PM - 3/23/21) A storm system will move through the region Thursday into Friday, bringing a low end and isolated severe t'storm threat to the southern half of the state and windy conditions to Eastern and Southern.
A storm system will move from the Plains on Wednesday night, through the Ohio Valley on Thursday, and into the Great Lakes by Friday morning. The northern side of a larger and more significant severe t'storm risk to the south will reach into the southern half of the state, with a low end and isolated severe t'storm threat expected Wednesday morning through Wednesday evening. Additionally, a period of windy conditions are expected across Eastern and Southern Illinois, Thursday afternoon through Friday morning.
Areas of rain and t'storms will spread across the southern half of the state, late Wednesday night into Thursday morning, as a warm front lifts towards and into Southern Illinois. In the wake of this early activity and with the warm front in the vicinity, a marginal environment will develop. This marginal environment will feature low instability, modest moisture and great shear. Additional areas of scattered showers and t'storms that develop along a cold front across Missouri and Arkansas during the afternoon, will spread across the southern half of the state Thursday afternoon through Thursday evening. Given the aforementioned marginal environment in place, a low end severe t'storm threat will exist with this activity, with isolated severe t'storms being possible. Hail, damaging winds and an isolated tornado will be possible with any severe t'storm.
In addition the the severe t'storm potential, windy conditions are expected Thursday afternoon through Friday morning across Eastern and Southern Illinois. High winds aloft, characterized by a low level jet of 50-75KT, will develop as the associated storm system rapidly strengthens as it moves through the region. The amount of mixing is in question... However, expected mixing depth will support wind gusts of 25-45MPH across Eastern and Southern Illinois, Thursday afternoon through Friday morning.
Below is the severe t'storm and wind forecasts for this event.