6/14/2010
Today ended up being a real surprise. Parameters came together to allow "mini supercells" to pop up over eastern Iowa and western Illinois. Mini supercells are basically smaller versions of the more common supercell thunderstorm. They are generally low-topped, and are a fraction of the size of the traditional supercell. Even with their small stature these things can still produce severe weather, including tornadoes.
The most dominant storm developed near Washington Iowa, and became tornado warned as it approached Muscatine Iowa. Around that time Jeremy and I decided to make a run at it, as it was expected to cross the Mississippi and head into Mercer County.
We blasted south out of the QC on I-74, and cut west towards Aledo. We passed through Aledo and approached the storm west of town.
After we got west of Aledo we got a better look at the thing.
We could see that it had the typical supercell structure. A nice inflow/beaver tail extended northeast of the updraft base. A very well defined notch could clearly be seen where the inflow met the RFD downdraft. Rotation was evident, but very weak.
Here's a few highly contrasted pictures of the notch and associated RFD downdraft/core.
Shortly after the above shots the RFD completely cut off the meso, so we pushed southeast as we expected a new one to develop south of the original meso. The storm had really hooked hard to the right, so we suspected the storm was just cycling.
Sure enough, 15 minutes or so later the storm reorganized, and a new updraft base and associated meso formed. At this point we were northwest of Alexis.
Here's a shot looking northwest at the quickly developing new updraft.
Before long a very short lived, and very weak funnel developed beneath the wall cloud.
The above funnel quickly vanished. We watched and waited as this storm very slowly approached our location from the northwest. The storm was only moving around 15mph, which was quite nice considering some of the storm speeds we had to deal with earlier in the season were over 60mph lol.
The updraft continually reorganized, as weak RFD notches kept knifing in. Many brief areas of rotations were noted as the storm attempted to tighten up.
All in all not a bad chase. Didn't even expect a chase today, so there's no complaints here. Mini-supercells are pretty rare around here in June, so that was kind of cool. The storms displayed fantastic structure for being so low-topped. I'll take storm structure like this anytime.
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