Severe thunderstorms in Iowa and Wisconsin headed east- Tornado watch possible for the Chicago area
The Storm Prediction Center in Norman, Oklahoma is considering issuing a tornado watch for northern Illinois that will likely include portions of the Chicago Metro area.
Mesoscale Discussion 1176 NWS Storm Prediction Center Norman OK 0632 PM CDT Wed Jun 28 2017 Areas affected...Northern IL Concerning...Severe potential...Watch likely Valid 282332Z - 290030Z Probability of Watch Issuance...80 percent SUMMARY...Tornado watch will likely be need soon for northern IL. DISCUSSION...Maturing MCS is organizing over northeast IA/southwest WI. Latest radar data suggests an expanding cold pool will aid east-southeast propagation of an elongating corridor of severe thunderstorms such that convection should spread south of WW377. Shear profiles remain supportive of storm rotation and isolated tornadoes can not be ruled out, though the primary storm mode may be clustering rather than discrete supercells.