2024-06-22 EVENT: IA/WI/IL

[Andy Wehrle]

Been monitoring Saturday 6/22 for local/regional chase potential for a few days now, signal has been there on the models but for most of the time nothing jumped out as particularly impressive. However, multiple 0Z CAMS (HRRR, 3KM NAM and HRW-FV3) tonight have shown rather potent solutions with some combination of discrete supercells and a potential derecho-producing MCS affecting portions of the titular Midwest states tomorrow afternoon/evening.

Positives appear to include generally stronger deep-layer speed and directional shear than we've seen with most of the "setups" thus far this June; and quite rich moisture.

Negatives are mediocre lapse rates (generally 6-6.5 degrees C/km at all levels) and a potentially complex surface pattern regarding where the best focus for supercell tornado potential will set up. The synoptic warm front is an obvious player, but there will likely be multiple outflow boundaries in play given multiple rounds of storms in the vicinity tonight and tomorrow morning. Of course, that's to be expected with most setups and even more so by late June.

Preliminary target is somewhere along a Waverly-Tama, IA line; unless more CAM solutions (other than the 0Z 3KM NAM) begin to converge on the idea of discrete supercells in southern Wisconsin.

 

[Robert S. Thompson]

I think there is some potential there. The challenge is that the cold front is likely to quickly sweep any cells into a line.

As of this morning's runs the models disagree about quickly the convection clears out of Wisconsin, so targeting Iowa makes sense - I would probably target a similar area to you, maybe a little more east.

RST