As of 3PM CDT the Severe Weather Outlook has been updated with no change to the Slight/Enhanced threats to the Chicago area. However there is now an increased Moderate Risk (45% chance of a severe storm within 25 miles of a given location) of Severe T-storms generating 75 mph winds or greater from eastern Lake Michigan through southern Lower Michigan/northern Indiana into Ohio (Red-shaded area on the headlined map).
Narrative from the Storm Prediction Center below:
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0317 PM CDT Mon Jun 13 2022 Valid 132000Z - 141200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF FAR SOUTHERN LOWER MICHIGAN INTO NORTHEAST INDIANA AND WESTERN OHIO... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE NORTHERN PLAINS... ...SUMMARY... Scattered severe thunderstorms are expected across parts of the northern Plains, and from portions of the Midwest into the Great Lakes and Ohio Valley. Large hail, damaging winds, and a few tornadoes are possible. Some of the winds could be significantly severe (75+ mph) across parts of the Midwest/Ohio Valley this afternoon and tonight. ...20Z Update... Portions of the Ohio Valley have been upgraded to a Moderate Risk for the anticipation of a highly organized MCS/possible Derecho developing from a supercell structure across southern WI. Despite the lack of agreement in high-resolution guidance, this supercell is traversing a strong buoyancy gradient (with extreme MLCAPE values exceeding 5000 J/kg noted in the OH Valley). In addition, 40+ kts of effective bulk shear are also present along the buoyancy gradient, which expands across a long west-east corridor over northern portions of the OH Valley. Expectations are for this supercell (which already shows an intense RFD surge per latest KMKX radar data) to eventually become more outflow dominant, generating a strong cold pool preceded by the extreme instability. Upscale growth with the cold pool would support an expanding MCS traversing a CAPE/shear parameter space typically associated with bow echoes/derechoes. In addition, multicells continue to percolate across central IN amid an extremely unstable environment (i.e. 5000+ J/kg MLCAPE per 18Z mesoanalysis) and an appreciable severe wind threat could develop with this cluster as well should upscale growth occur. A significant wind area has been added to portions of the Slight Risk across portions of central into northern South Dakota. Here, the potential exists for an HP supercell/short bowing segment to manifest from earlier storms along or immediately behind the surface cold front somewhere within the 03-06Z period (especially in the 12-18Z runs of the HRRR) and traverse an axis of high-end elevated buoyancy (i.e. 4000 J/kg MUCAPE driven by 9 C/km deep-layer lapse rates). Should this scenario unfold, 75+ mph gusts may occur in addition to 2+ inch hail. Consideration was considered for an upgrade to a Category 3/Enhanced. However, the localized nature/expected limited coverage of the higher-end severe threat precludes an upgrade. Please see MCD #1144 for short-term severe concerns across the northern Plains.