• Andrew Pritchard

April 8th 2020 | High-based supercells in central Illinois

A weird setup presented itself across central Illinois on Wednesday, driven largely by steep lapse rates and an EML plume from the southwest. The air mass was rather moisture starved, with dewpoints mixing into the 40s across the region, with afternoon surface temperatures surging into the lower 80s sending LCLs up to around 2500m. Still, a potent northern stream shortwave was approaching from the northwest and was forecast to kick off an initial round of high-based supercells that would eventually congeal into one or two quick-moving QLCS.


High-based supercells initiated around 2 PM near the Iowa/Missouri border and crossed into Illinois about an hour later. I initially left Champaign-Urbana and picked up Hwy 136 targeting a storm that had developed near Keokuk, IA and was now impacting the Macomb, IL area.


Additional convection began blowing up around this initial supercell and it began taking on a more messy look, at the same time that a new storm with clean air to its south began to take off.



The storm was near the Beardstown area, crossing the Illinois River and entering some pretty rough terrain. I decided to take my time getting in front of it, and plotted a course cutting in front of it and eventually getting a view of the updraft base on the west side of Springfield. In hindsight I'd ended up wishing that I'd played it even more conservative and waited to intercept on the east side of Springfield to give myself a little additional space.


I was never even able to stop the car and look at the storm as outflow began surging ahead and the storm's forward motion began to increase. I quickly looped around from the west side of the Springfield metro, around the south side, to the southeast side, and then picking up Hwy 29 toward Rochester just to get some space between myself and the hail core which was warned for ping-pong ball sized hail.




By the time I got to Rochester, outflow was now kicking up dust plumes from the dry, freshly tilled farm fields in the area. I knew my time with the storm was fairly limited at this point and was just looking for ominous outflow scenes. Blowing dust, howling power lines, that eerie outflow experience.


I found a few neat scenes between Rochester and Mowequa before new convection on the outflow blew up behind and to my south, closing me in. I continued zig zagging south and east along the gridded farm road network as long as I could before picking a relatively weak echo region in the line hoping to avoid the hail, and let the storms overtake me.



After letting the stronger cores pass, I found my way back to the highways and decided I would slowly make my way back toward home in Champaign-Urbana, but take my time allowing the sun to get low on the horizon and perhaps light up the back side of the storms, or to enjoy the stratiform precipitation region lightning show.



The lightning on the drive home was rather spectacular, but the sunset left a lot to be desired.


I pulled off to tripod some of the now distant lightning from just south of Tolono, IL in Champaign County but once the cold north wind began to howl, I made my way home.




















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