(11:15PM – Tuesday, April 1st, 2025) Tuesday night update on a potent storm system that will move through the region, bringing a few waves of shower/t’storm activity across the state between early Wednesday morning and Wednesday night. Severe t’storms will be likely with some of this activity.
Timing…
•Early Wednesday Morning – Wednesday Night, April 2nd.
Location…
•All of Illinois.
Impacts…
•A level 1 to 3 severe t’storm risk is in place across much of the state for the likelihood of isolated to scattered severe t’storms.
•All modes of severe weather will be possible, including large hail, damaging winds and a few tornadoes. The tornado threat will be maximized across Northwestern, Eastern and Southern Illinois.
•Environmental conditions will be supportive of the possibility of occurrences of: Strong tornadoes, long track tornadoes, damaging winds 75MPH+, corridors of widespread/significant wind damage and hail larger than 2.00”.
Update…
•With this update, little to no changes were made. There is still uncertainty revolving around how activity will evolve overnight tonight and into Wednesday morning, which will impact the threat on Wednesday itself. This uncertainty will be resolved by our final forecast issuance, later Wednesday morning.
Discussion…
•Multiple waves of shower/t’storm activity will be likely across the state between early Wednesday morning and Wednesday night, as a storm system moves through the region.
An initial round of widespread showers and t’storms had begun to affect portions of Northern and Central Illinois tonight. Additional activity will develop and traverse portions of Northern Missouri, Iowa, Northern and Central Illinois from tonight into early Wednesday morning, as a warm front begins to lift northward and warm air advection occurs. An isolated strong/severe t’storm will exist with this activity, late tonight/early Wednesday morning. Hail will be the main threat should any isolated strong/severe t’storms occur.
Beyond this, a weakening and broken line of rain and t’storms will enter the Northwestern-Western-Southwestern Illinois early Wednesday morning. This activity will be remnants of severe t’storm activity occurring across the Plains this evening and tonight. An isolated strong/severe t’storm threat cannot be ruled out with this activity, with wind and hail being the threats. As this weak activity spreads further across the state on Wednesday morning, it will throw a wrench into how exactly the rest of the day will play out. There are a few possible scenarios that could potentially result. The most probable scenario at this moment in time is that this early-day activity will fester throughout the morning across the state, with re-intensification and development of new activity to occur during the afternoon in the undisturbed open warm sector, which will reach into Eastern and Southern Illinois. Once this occurs, this activity will traverse these portions of the state into Wednesday night. Further to the north and west, across much of Northern and Central Illinois. The threat is dependent on enough recovery occurring, allowing for another round of activity to develop. The most probable scenario at this moment is that a corridor of some recovery occurs across Northeast Missouri, Eastern Iowa, into Northern and West-Central Illinois. A very broken line of showers/t’storms may develop along and ahead the main advancing cold front, with this activity then traversing Northern and West-Central Illinois should it develop. A severe t’storm threat will be possible with this activity, should this scenario unfold, with all modes of severe weather then being possible. Across this corridor there is the potential for an upgrade or downgrade in severe t’storm threat level, bending on how morning activity plays out.
