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Chase Log: June 22nd 2024 - Long-Lived Mini-Supercell in Iowa

Saturday was a long day. As you may have read during my last forecast and chasing discussion on Friday evening I had mostly fallen out of love with the potential storm observation opportunities in the Midwest for the 22nd. Poor lapse rates and an initiating boundary parallel to the deep layer shear vector should lead to messy storm modes with little tornado potential. My wife Sophie was headed to a little backyard birthday gathering with a friend on Friday night and I decided to pivot into "have a fun late night with the wife, sleep in Saturday, enjoy storms at home later in the evening" mode. We got home a little after Midnight and I went straight to bed without really looking at the 0z model runs.


I had hoped to sleep in on Saturday morning - as an early riser Monday-Friday, sleeping-in on Saturday morning is like 7 AM - but I woke up around 5 AM instead after a little under 5 hours of groggy sleep. Rolling over and grabbing my phone, a friend had texted me a snippet of the SPC Day One severe weather outlook discussion that mentioned supercells and tornadoes, and another group chat was beginning to look at Saturday as a possible chase day again too. I got up and poured a cup of coffee and moved to the couch and put the Weather Channel on for vibes.


That's when it hit me - the air conditioner / furnace blower was silent. I have been fighting a nagging, stupid issue with the HVAC system where it'll just shut off, and I can no longer get it to click back on. Long story short, I'd had an HVAC tech out to repair the issue last fall, and then had two guys out on Friday morning. Every time, they'd get it running again and get the house cooling down only to have it shut back off when they left. So here I am now on Saturday morning, forecast high temperature of 94 degrees, and the a/c is once again unresponsive.


This soured my entire mood. Now I'm waiting for an HVAC tech, worried about my house overheating and the potential that at some point this is going to stop being simple wiring or door-switch related issues and I'm going to have to replace the whole damned HVAC system. I complained to my chasing friends that I just wasn't feeling an uncertain storm chase a 4-5 hour drive one-way with my bad mood and uncertainty at home. Sophie and I took the dog for a walk in the neighborhood and I vented my frustrations. She was more than happy to be home and deal with the HVAC tech if I wanted to leave for the day, and I could tell that my "should I chase, should I not chase" indecision was starting to get annoying so I made the call - I'm just gonna go.


Being in such a sour mood I decided I wanted to chase the day solo so that I could let my manic energy drive the day. I was into the chase, but reserved the right to bail on the day or adjust my target wildly for whatever reason I wanted. I told Colin and my other buddies I was down to meet up out there, but I wanted a day alone in my car with my own thoughts.


Threw my crap in the car and hit the road at 10 AM, kind of the last-call time that I'd set for myself earlier. If I didn't leave by 10, I might as well stay home because I'd probably be too late for the 3 PM storm initiation in north-central Iowa. There was a small part of me that considered heading to southern Wisconsin for the evening show, but decided the potential for a couple hours of a supercell or two or three in northeast Iowa seemed like a better play.


I'm not proud of how I treated my body on Saturday, but after a night of too-little sleep and a stressful HVAC morning I left the house with only a couple cups of coffee and a donut in my belly. I grabbed a cheeseburger from the Culvers in Morton, IL right as the HVAC tech called me with good news from the homestead - the a/c was again running with another fairly simple replacement and no service call charge.


Okay, mood-shift. I've got a burger and a fountain coke, my wife and dog aren't going to heat exhaust, and the repair didn't break the bank. Let's go see a supercell!


Around 3 PM a persistent, rotating spud developed near Iowa Falls, northeast of Des Moines. As I approached from Waterloo/Cedar Falls I realized this was not a struggling little spud, but a mini-supercell! A photo from someone closer confirmed, this was a full-fledged rotating storm!


Poor mid-level lapse rates did present themselves, but not necessarily in the way I expected. Instead of messy storms with upscale growth, the modified outflow regime fostered a long-lived mini-supercell that persisted for three hours as it tracked from Iowa Falls to Dubuque. The storm produced numerous wall clouds and a few attempts at tornadoes. One attempt resulted in us being impacted by a weak ground circulation, another resulted in a cool horizontal funnel / tube near Greeley, IA.


Strong RFD surges continued to blow apart gentle, vorticity-driven tornadogenesis attempts and kept the storm moving at a surprisingly fast eastward clip of ~ 50 MPH. On a day that I expected storm motions to be closer to 20-25 mph, this was frustrating as it was difficult to enjoy the storm and get any tripoded video shots. Much of the chase was spent driving east to get ahead of the storm, only to stop and look and have the storm quickly pass us back up.


As the storm entered the Dubuque, IA region and crossed the river into southern Wisconsin I let it go. The storm was not necessarily dying, but it would merge with a larger storm complex and continue quickly east and I'd had my fun for the day. I was at a main highway that would start angling me back toward home, and additional storms would eventually start to form and overtake my route home. Might as well enjoy a beautiful summer evening drive home and avoid driving through rain and lightning.


I wanted some ice cream to enjoy after the chase so I swung through Dairy Queen for dinner on the way home and pulled into the driveway in Urbana right around 11:00 PM. For a late-June storm chase out-of-state, that's really reasonable. Most chases this time of year are going to end with or near sunset, which is as late as 8:30 or 9:00 - begin the 4 to 5 hour drive home then and I'm returning at 2 or 3 AM. For my tired self, 11 was great. A lot of times I'm keyed up after a chase and even though I'm tired, I'll need an hour or two to wind down by editing some video or catching up on social media. Not this time though, exhausted I went straight to bed in the clothes I'd chased in and fell immediately asleep.


Some video highlights from the day:



Images from the day:


Early wall cloud near Parkersburg, Iowa:


More wall clouds:



Horizontal funnel / tube near Greeley, Iowa:



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