Mesoscale Discussion 1450 NWS Storm Prediction Center Norman OK 1218 PM CDT Mon Aug 09 2021 Areas affected...Portions of northern IL and extreme northwestern IN Concerning...Severe potential...Watch possible Probability of Watch Issuance...60 percent SUMMARY...A threat for large hail, damaging winds, and a couple of tornadoes should increase this afternoon. Watch issuance is possible. DISCUSSION (paraphrased) ...Storms are ongoing across portions of northern Illinois. In the wake of tese storms, the air mass is expected to become quite unstable and new storms are likely to develop southwestward across northern Illinois by 3-4 PM CDT. Conditions favor the development of a few supercells capable of producing large hail, damaging winds and a few tornadoes. A small cluster of storms may eventually develop as activity moves slowly south-southeastward toward NW Indiana. If this occurs, then severe/damaging winds may eventually become the primary threat. The potential for surface-based storms should increase over the next couple of hours as surface temperatures warm into the low 80s, and watch issuance is being considered in this time frame.