June 21, 2018

Statistics

Initial Target

Start

End

Storm Intercepts

Tornadoes

Hail

Wind

Features

Miles

Bloomington, IL

Springfield, IL 1:04 PM 6/21/2018

Springfield, IL 8:57 PM 6/21/2018

Gridley, IL

0 mph

Brief Tornado, Wall Cloud, RFD Clear Slot

225

Summary

Cold core/warm front setup in central Illinois. Targeted Bloomington for midafternoon low topped cells capable of spinning up funnel clouds. Noted brief, weak tornado south of Gridley, IL followed by some supercell structure from a low topped cell as it crossed the warm front.

Crew and Equipment

Solo chase. Equipment: Sony AX100, Canon 60D, Samsung S7 Edge.

Video

Map

Details

There was a local, quasi-cold core/warm front setup in Illinois on June 21. I didn't have any real expectations that this would be a real chase opportunity, but it seemed like the kind of setup that could spit out a funnel cloud, or maybe a weak tornado with low topped storms tapping ample low level instability and helicity on the warm front.

I ran northeast out of Springfield to north of Bloomington. A short arc of cells was lifting north across the warm front. It looked like they were briefly organizing as they crossed the boundary with a rain free base and lowerings.

Brief Tornado
4 miles S of Gridley, IL
3:04 PM

A middle cell in the line rapidly organized, developing a block wall cloud with tail that dipped low into the forward flank precipitiation core. Twisting condensation spiralled up from the northern tip of the wall cloud. It was distant and low contrast, but it looked like a tornado was in progress.

I got the cameras zoomed in on it, and then later reviewed the footage in the field. I don't think the cell was warned at all, but this feature was definitely rotating (although not super fast) and solidly surface based, so I hopped on Twitter to report a tornado to the National Weather Service.

The tornado looked like it lasted for less than a minute and was probably pretty weak.

It dissipated in twisting, wispy shards of cloud.

Tornado and Storm Structure
4 miles S of Gridley, IL
3:04 PM

Wider/unzoomed shot looking southwest showing the small tornado underneath the wall cloud, RFD gust front to the left, and FFD core to the right.

Mini-supercell
5 miles ESE of El Paso, IL
3:10 PM

The chase was on now for real! I moved in to get closer and track with the cell. Midlevel rotation in the mini-supercell persisted, along with a big RFD cut and additional lowerings. The storm was done producing tornadoes, however.

Small Cells

3:49 PM

I tracked a few more cells that were little more than glorified rain showers, hoping for some additional warm front magic. Lots of scuddy lowerings, but nothing that looked like a well formed funnel that I could find.

My after-the-fact report made the Local Storm Reports.

Conclusion

A little warm front magic with a brief tornado on a no expectations day is always a great score. The Weather Service followed up with me to log the tornado in the database after I sent them video of the event. The tornado probably did little to no damage, perhaps even occurring over Lake Bloomington.

Lessons Learned

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