(11:45PM - 6/18/21) A storm system will move through the region on Sunday, bringing a severe t'storm risk to a large portion of the state.
. A storm system will move across the Plains Saturday night, through the Midwest and Great Lakes on Sunday, and to into the Northeast by Monday. This storm system will bring a severe t'storm risk to a large portion of the state for Sunday afternoon through Sunday night. Model guidance has been showing this potential for a few day now, and potential has been increasing as we approach the event.
Sunday Afternoon-Sunday Night...
A lead disturbance is expected to move from Iowa and Missouri Sunday morning, across Illinois Sunday afternoon, and then into Michigan Sunday night. The development of t'storms associated with this disturbance is possible across Eastern Iowa and Northern Illinois Sunday afternoon. This activity would then spread northeast across Northern Illinois Sunday afternoon. Further west along the cold front, additional showers and t'storms will develop Sunday afternoon. This activity will spread eastward across a large portion of the state, late Sunday afternoon through Sunday night. An environment supportive of a severe t'storm threat will be in place. This environment will feature moderate to high instability of 2,000-4,000J/KG, dew points in the mid 60's to mid 70's, high shear and strong forcing. This environment will be supportive of upwards of a isolated to widely scattered severe t'storm risk (level 1-2) across the heart of the state. Damaging winds, large and and a few tornadoes will be the main severe weather threats.