(11:15AM – Tuesday, April 1st, 2025) Tuesday morning 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 early Wednesday night. Severe t’storms will be likely with some of this activity.
Timing…
•Early Wednesday Morning – Early 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, we have increased severe t’storm probabilities and added significant severe t’storm hatching across the northwestern chunk of the state. This change was based on an overall swing in weather guidance overnight and this morning, depicting a more favorable scenario for an increased severe t’storm threat across this area. Outside of this, elsewhere across the state, little to no change was needed.
Discussion…
•Multiple waves of shower/t’storm activity will be likely across the state between early Wednesday morning and early Wednesday night, as a storm system moves through the region.
An initial round of widespread showers and t’storms 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, mainly after midnight 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 expected to occur 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 a bit, but generally start to clear, throughout the morning across the state, with re-intensification and development of new activity to occur 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 early 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 adequate recovery occurs across Northeast Missouri, Eastern Iowa, into Northern and West-Central Illinois. A broken line of showers/t’storms will develop along and ahead the main advancing cold front, with this activity then traversing Northern and West-Central Illinois. A severe t’storm threat will then be likely 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.
In summary…There are still many questions with the evolution of the severe t’storm threat across the state for this period. As we move closer to the event and with additional weather guidance data coming in, adjustments to the forecast will be likely.
