(11:30PM – Wednesday, May 14th, 2025) Wednesday night update on storm system and a few main disturbances move through the region, which will bring a couple of rounds of rain and t’storm activity to the state, from tonight through Friday night. Severe t’storms will be likely with some of this activity.
Timing & Location…
•Tonight – Thursday Morning, May 14-15th: Large portion of Illinois.
•Thursday Morning – Friday Morning, May 15-16th: Much of Illinois.
•Friday Morning – Friday Night, May 16th: Central & Southern Illinois.
Impacts…
•A level 1 severe t’storm threat is in place across a large portion of Illinois, from tonight through Thursday morning, for the possibility of isolated severe t’storms. Large hail and damaging winds will be possible with activity. Environmental conditions will be supportive of the possibility of occurrences of hail larger than 2.00”.
•A level 1 to 3 severe t’storm threat is in place across much of Illinois on Thursday, for a threat of isolated to scattered severe t’storms. Environmental conditions will be supportive of the possibility of occurrences of strong tornadoes, damaging winds 75MPH+, corridors of widespread/significant wind damage, and hail larger than 2.00”.
•A level 1 to 3 severe t’storm threat is in place across Central and Southern Illinois on Friday, for a threat of isolated to scattered severe t’storms. Environmental conditions will be supportive of the possibility of occurrences of strong tornadoes, damaging winds 75MPH+, corridors of widespread/significant wind damage, and hail larger than 2.00”.
Update…
•With this update, no changes were needed on the severe t’storm forecast for tonight through Thursday morning.
•With this update, we have slightly expanded level 2 and level 3 severe t’storm probabilities across portions of the state, as confidence increases in higher coverage severe t’storm potential being possible.
•With this update, we have issued our first severe t’storm forecast for Friday.
Discussion…
•Tonight – Thursday Morning, May 14-15th: As a storm system approaches the state and enters the region, a warm front will lift northward across the state from tonight through Thursday morning. Isolated to scattered showers and t’storms will develop along it, lifting northward with the front during this timeframe. Environmental conditions will be supportive of a severe t’storm threat with some of this activity.
•Thursday Morning – Friday Morning, May 15-16th: As a strengthening storm system lifts through the Midwest, an arcing cold front will sweep northeastward across Minnesota, Iowa, and Wisconsin. Further south, a dry line will also sweep eastward, from Iowa and Missouri, quickly into and across Illinois. Much of Thursday morning through roughly mid-afternoon will be dry across the state, as a cap will be in place, preventing any notable shower/t’storm and severe t’storm development. By mid to late afternoon, as the cap is projected to erode/weaken, there is a conditional threat that isolated to scattered showers and t’storms will develop along the advancing dryline moving across the state. As of this forecast issuance, the greatest potential for this to occur, and thus, the greatest coverage of activity, may very well be across Northeastern Illinois and vicinity. Environmental conditions will be favorable for a severe t’storm threat should this scenario come to reality, including the threat for all modes of severe weather and occurrences of significant severe weather.
•Friday Morning – Friday Night, May 16th: Specific information regarding Friday’s severe t’storm threat will be provided in future updates.
