June 20th 2015 Iowa Squall Line – Eddyville Tornado.

Dec 01, 2015

Summary:

Tracked intense squall line across southeast Iowa – getting very near QLCS tornado near the town of Eddyville.

Stats: 

Tornadoes: 1
Hail: 1.25″ (half dollar)
Wind: est 60-70mph inflow to QLCS tornado

The Forecast:

High Cape, stalling frontal boundary with jet streak moving in to trigger more storms. Shear profiles largely unidirectional but some slight turning in the low levels meant storms could be discrete early on. In addition, multiple outflows would be present that could promote low level rotation if interacted with favorably.

Detailed Account:

It’s been a pretty active and stormy June across the midwest, with numerous rounds of severe storms and a few big local events near home. This was yet another setup in the mix. Discrete supercell potential was a concern, but it was a Saturday and being so close chasing was a no brainer. I left Chicago with a target somewhere east of Des Moines depending on where the boundary would set up. I made pretty good time, on my way out an ongoing storm north of New Liberty gained a severe warning for tennis ball size hail so I made a quick detour to check it out. The storm began dissipating as I arrived, shedding its base into a pretty dramatic roll cloud.
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Alright not bad for just driving out to the target area. Surface obs showed the best wing backing near Grinnel, so I decided to head there. Visible satellite also showed a deep cu filed ahead of an advancing boundary over Des Moines, so this seemed like a good spot. I was not the only one to notice this apparently, and a large chaser convergence was gathered at a gas station off the interstate. We would sit there for a little over an hour before the first signs of initiation were to take place. I moved south to get on the first developing storm, but it quickly began lining out. Not too surprised by that.

I got under the base quickly though, which dealt an impressive barrage of CG lightning in the very high dewpoint air. A few sporadic hailstones up to half dollar size began dropping. I made a quick SN report and moved to stay with the storm. It displayed a nice inflow tail but not much of a rain free base and was very HP.  
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The CG barrage remained quite impressive, one of the strongest of the year actually, but by now multiple storms were merging together and a large linear complex was now developing. The supercell tornado threat was over and the hope now was for catching anything that would be embedded as a QLCS type circulation. I cat-n-moused the complex for a couple hours. Receiving occasional bursts of severe wind gusts that would bring down trees. All the while the storm maintaining its HP, but dramatic appearance.
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Around the town of Eddyville things got interesting suddenly things got very still. I looked up and could see a large area of rotation overhead.
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The swirling mass seemed to be moving the opposite direction while a large area of rain bowed out ahead of it. Winds were rapidly changing directions and I started to suspect I was in or very near some type of circulation. I stayed with it best I could following the highway I was on and at one point noticed a couple small points that resembled nub funnel clouds.
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Eventually the area slipped south of me from the road and I was overtaken by the blinding rains and strong winds that sent tree debris flying everywhere. I passed some pretty heavy tree damage shortly after. The area was now tornado warned with a decent signature on radar. This was likely a QLCS type circulation. I kept moving forward though as making any type of play to see a tornado seemed like it would be fruitless. The complex was moving at a pretty quick pace so I opted to stay ahead of it in case anything similar developed again.

Reaching Mount Pleasant I pulled into town just ahead of the line, which was severe warned and had reported damage almost along the entire way. I found a parking lot and decided to film the impact, which brought perhaps 60mph winds, causing only light tree damage where I was at. By now the sun was getting ready to set. Ben Holcomb and Bart Comstock were in the area, and I decided to meet up with them and join them in an overnight stay in Peoria. The next day held marginal potential across Central or Southern IL so we decided to stay there in case we wanted to give that a shot.

We awoke the next day, went to a nearby casino where I suffered a brutal roulette loss, and decided the thunderstorm risk wasn’t worth it so I headed for home while Ben and Bart headed back towards Ben’s home town in Michigan. Models were hinting at something big coming the next day (the 22nd) and we wanted to be ready for it.

Conclusion:

The NWS did conclude an EF-1 QLCS tornado just south of Eddyville, and although there was no real visible tornado funnel with which to identify it. I am certain I was in the outer edge of the circulation as it developed so it goes up on the tally for the year. Overall the chase played out how I thought it would, and I consider it to be a solid late season chase. A few good structure shots added to the mix as well. Ill take it.

Radar from NWS, with  my location plotted along Higway 62
radar

Map:
620m

NWS Survey info:
Tors

SPC Reports:

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