July 18th 2015 – Weak Tornado Near the Wisconsin Border

Dec 21, 2015

Summary:

Chase a pair of supercells in a weakening phase, catching what is probably the weakest tornado I will ever see.

Stats:

Tornadoes: 1
Hail: .25″
Wind: n/a

The Forecast:

Zonal flow regime with shortwave energy moving through it. Sufficient deep moisture in place in typical summer-like airmass. Moderate speed shear present in southern end of zonal jet. Morning storms would kick off an outflow boundary that could serve as a focus for a new round of storms. SPC began the day with a SLGT risk but upgraded to ENHANCED for damaging wind potential as storms were forecast to grow upscale into large MCS. Earlier supercell potential came with tornado threat. Complicating factor would be cloud debris and less destabilization than what was forecast.

Detailed Account:

On paper this setup appeared sloppy to me, but it was a Sunday so what else would I be doing? Being local I had to try. I decided to head up towards Alec Scholtens house located near the WI/IL border. There, we agreed was the best spot for initiation along the slowly sagging cold front. We sat in a Loves parking lot for a few moments when the first storms of the day went up nearly overhead. To our dismay they were going up quickly and close together, taking on linear structures.

We jogged north into Wisconsin before heading east to get on what appeared to be the most isolated storm. The storm had some nice backside structure.
July 2015 Harvard Illinois

We got ahead of the storm, as it was tornado warned with reported funnel cloud from another storm chaser in the area. Moving into position, features were hard to see, but winds were quite gusty. Terrain and road network is not the best here, but we managed to get where we needed to be as Alec spotted something suspicious. I pulled over, swung the vehicle around to see tree debris swirling nearby. The rotation on radar was weakening, and this was the dying tornadic circulation actually reaching the gound. The leaves swirled as they crossed the road, impacting a tree which bent over in the winds, but never snapped. I was able to note a very faint condensation funnel for a brief moment, as the circulation moved on and un-visible for us. It was literally the weakest, saddest tornado we’ve ever seen.

I did catch it on video though, which can be seen here: https://www.facebook.com/TornadoChasing/videos/vb.167447826684097/841594245936115/?type=3&theater

After this, all the remaining storms appeared rather junky, but we moved to take a look anyways. They were rather feature-less and weakening on radar, but still somewhat ominous.
Hebron Illinois July 18 2015

This storm weakened shortly after and was not worth pursuing. With no further development taking place we decided to head back to Alec’s house and wait any new development. It was only 3pm or so and the day was probably over. New storms never formed as it appeared the airmass could not recover in time from earlier convection and a stronger cap than what was forecast. We met up some friends for a birthday dinner, and I made my way towards home.

Conclusion:

Yay for adding another tornado to the tally, but it was pretty laughable how weak it was. It was likely more intense before we got on it though, and several areas of damage were found while crews conducted surveys. Aside from these weak tornadoes, the day was mostly a bust, with the larger scale MCS never forming. Still, for a weekend local chase that requires barely a tank of gas, it beats sitting at home. If our weak little tornado would have occurred just a few miles further north, it technically would have been my first Wisconsin tornado, so close.

Map:
7-18m

SPC Reports:

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