Mesoscale Discussion 1465 NWS Storm Prediction Center Norman OK 0310 PM CDT Tue Aug 10 2021 Areas affected...Portions of southern and eastern Wisconsin Concerning...Severe potential...Watch likely Valid 102010Z - 102215Z Probability of Watch Issuance...80 percent SUMMARY...Watch likely by 21Z. DISCUSSION...A boundary has become more diffuse as if lifts north across southern Wisconsin over the past hour with occasional convective attempts. If storms go up along this boundary, a watch may be needed soon as extreme instability (MLCAPE around 4500 J/kg) should support explosive storm development. Averaged effective shear between KGRB and KDVN 19Z RAOBs shows around 25 knots. This would be sufficient for multicell storm modes with a threat for both large hail and damaging winds. However, even if storms do not develop along this boundary, a watch is likely eventually as storms move in from the west. Storms across eastern Iowa have started to organize and it appears they may be clustering in northeast Iowa. This may be the beginning of upscale growth into an MCS which would likely track across southern Wisconsin. A watch is likely by 21Z.