(10:30PM Tue, July 18th 2023) Tuesday 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.

Update…

•With this update we have adjusted severe t’storm probabilities on tonight’s forecast, based on real time information, trends, and the latest model guidance.

•With this update we have increased and expanded severe t’storm probabilities across portion of the state on Wednesday/Wednesday night’s forecast, based on real time information, trends, and the latest model guidance.

•With this update we have issued our first forecast for Thursday severe t’storm threat.

​Timing & Location…

•Tonight – Early Wednesday Morning, July 18-19th: Southern Illinois.

•Early Wednesday Morning – Early Thursday Morning, July 19-20th: Southern Illinois.

•Thursday, July 20th: Northwestern, Western & Southern Illinois.

Impacts…

•A level 1 to 2 severe t’storm risk is in place across Southern Illinois, from tonight through early Wednesday morning. Isolated to widely scattered severe t’storms will be likely, posing a risk of damaging winds and large hail.

•A level 1 to 2 severe t’storm risk is in place across Northwestern, Western and Southern Illinois, from early Wednesday morning through early Thursday morning. Isolated to widely scattered severe t’storms will be likely, posing a risk of damaging winds and large hail.

•A level 1 to 2 severe t’storm risk is in place across Northeastern, Eastern and Southern, from early Thursday morning through early Thursday night. Isolated to widely scattered severe t’storms will be likely, posing a risk of damaging winds, large hail and an isolated tornado.