(10:30PM Mon, July 17th 2023) Monday night update, regarding multiple disturbances and storm systems that will continue to move through the region through Thursday, along the southern flank of mean troughing in Canada/Great Lakes, and along the northeastern periphery of a ridge in place across the Desert Southwest/Southern Plains. This pattern will continue to support daily chances for rain/t’storms and severe t’storms across portions of the state during this period.
•With this update we have adjusted severe t’storm probabilities across Central and Southern Illinois on tonight’s forecast, based on real time information, trends, and the latest model guidance.
•With this update little to no changes were needed on Wednesday/Wednesday night’s forecast.
•With this update we have issued our first forecast for Wednesday/Wednesday night’s severe t’storm threat.
Timing & Location…
•Tonight – Early Tuesday Morning, July 17-18th: Central & Southern Illinois.
•Early Tuesday Morning – Early Wednesday Morning, July 18-19th: Southwestern & Southern Illinois.
•Early Wednesday Morning – Early Thursday Morning, July 19-20th: Southern Illinois.
•Thursday, July 20th: TBD.
•A level 1 severe t’storm risk is in place across Central and Southern Illinois, from tonight through early Tuesday morning. Isolated severe t’storms will be possible, posing a risk of damaging winds and large hail.
•A level 1 to 2 severe t’storm risk is in place across Southwestern and Southern Illinois, from early Tuesday morning through early Wednesday morning. Isolated to widely scattered severe t’storms will be likely, posing a risk of damaging winds, large hail and an isolated tornado.
•A level 1 severe t’storm risk is in place across Southern Illinois, from early Wednesday morning through early Thursday morning. Isolated severe t’storms will be likely, posing a risk of damaging winds and large hail.
•A severe t’storm risk will exist on Thursday as well. More specific information regarding potential this day is to come in future updates.