July 19, 2018 Iowa Tornado Outbreak

Summary:

A localized significant tornado outbreak took place over Central and Southeast Iowa on the afternoon of July 19, 2018 producing numerous photogenic and strong tornadoes. Leaving Galesburg by late morning, we were able to get onto a tornadic supercell that fired near Des Moines, Iowa and track it from near Prairie City, IA southeast to the Missouri border documenting several tornadoes and severe wind gusts.

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Date: July 19, 2018

Large EF3 Tornado near Pella, IA. July 19, 2018. Photo taken by Ethan Schisler

Miles Driven: 420
Chase Partners: Ethan Schisler/Cory Marshall; Kholby Martin
Tornadoes: 5-6
Largest Hail: Quarter
Top Wind: 80+ MPH
States Chased In: Iowa
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Details:

It had been a very slow 2018 season and many chasers were frustrated by the lack of activity. Our last *good* chase-day was on May 1st in Northern Kansas where we intercepted several tornadoes. This was the our next good chase day in a year of limited opportunities. The weather setup for this day was a warm front draped from NW to SE across Iowa into Illinois. The SPC had highlighted a 2% probability of tornadoes noting storm mode as a potential issue.

Day 1 Tornado Probabilities

 

A warm front had set up over Southeast Iowa with temperatures into the upper 70s, near 80 and dew points pushing into the 70s south of the front. This was creating very high amounts of instability, especially low level instability which was perfectly co-located with the highest amount of surface vorticity.

Surface observations over Central/Southeast Iowa

Surface instability was increasing as aforementioned with values nearly maxed out along the warm frontal boundary.

0-3km CAPE

Cory Marshall and Ethan Schisler were able to leave Galesburg around 11am that morning, arriving in the target area by 2pm in Central Iowa. We initially awaited the tornadic storm outside of Colfax, Iowa. The storm had already produced a few tornadoes near Des Moines. The Storm Prediction Center had issued a tornado watch around this time highlighting the potential for a few tornadoes in the area:

Tornado Watch issued for Central Iowa

Radar showed one tornadic storm that had developed and we were able to drop south out of Colfax, Iowa to get a view of the storm base. Our first official tornado of the day was on the northwest side of the town of Prairie City, Iowa where we caught the rope out of the Prairie City, IA around 3:25PM. Here is the tornado track from NWS Des Moines followed by an image I was able to capture. I mainly focused on photography for this particular chase:

NW Prairie City EF0 Tornado

Brief Tornado near Prairie City, IA

We followed the storm southeastward out of town toward highway 14 where another mesocyclone would develop and produce a cone funnel that briefly touched down before becoming rainwrapped, which would be rated EF-0 as well. Here are a couple images west of Reasnor, Iowa.

Funnel developing and touching down west of Reasnor, IA

Tornado fully condensed west of Reasnor Iowa.

This tornado eventually became so rainwrapped that we couldn’t visually see it anymore. So I decided to head east toward Reasnor and then southeast where we got a view of another mesocyclone that had developed. The base came into view just outside the town of Monroe, IA.

Mesocyclone near Monroe, IA

As we continued southeast, it would produce a distant tornado. We were on the west side of the storm at this point as it accelerated southeastward. This would typically be a good viewing point for supercell tornadoes with excellent lighting conditions, however on this day, severe RFD in the form of 80+ mph winds caused serious driving issues, nonetheless we were able to eventually catch up.

Distant Monroe Iowa Tornado

Zoomed in shot of stovepipe tornado under incredible RFD structure

Continuing southeast, it didn’t take long before the supercell produced its main tornado of the day. A large EF3 near Pella, Iowa. We continued shifting southeast on the area road network before the large tornado came into view. The radar showed a classic supercell with hook echo and strong rotation at the time:

Classic supercell on radar near Pella, IA

 

 

Large EF3 Tornado near Pella, IA. July 19, 2018. Photo taken by Ethan Schisler

The tornado was doing EF3 damage here with winds up to 155 mph on the north side of Pella, IA including a large equipment plant that was completely destroyed. It would constrict some and continue tracking southeastward where I captured additional images of the tornado. At one point there was a satellite tornado to the east of the main tornado that we visually saw, but were unable to capture on camera:

Stovepipe tornado captured near Pella, IA, July 19, 2018. Photo taken by Ethan Schisler

 

 

Strong stovepipe tornado near Pella, Iowa exiting town

 

 

 

 

Wide angle of the Pella, Iowa tornado and storm

The tornado would briefly become larger/wider at the base before becoming totally rainwrapped again:

Tornado becoming rainwrapped as it passes to our south.

Tornado becoming very large as it passes southeast of Pella, Iowa

Meanwhile further east, Kholby Martin and his dad were coming in to intercept the storm. They would be able to intercept the storm further east between Leighton and Pella capturing these images as the tornado finally dissipated:

Tornado east of Pella, IA. July 19 2018. Photo by Kholby Martin

 

 

Tornado east of Pella, IA. July 19, 2018. Photo by Kholby Martin

Tornado east of Pella, IA. July 19 2018. Photo by Kholby Martin

Tornado dissipating near Leighton, Iowa. July 19 2018. Photo by Kholby Martin

I tracked the supercell further southeast toward Ottumwa where it produced 1 more confirmed tornado outside of Oskaloosa, Iowa. I originally wasn’t able to visually see the tornado until I contrast enhanced my images. NWS Des Moines confirmed that an EF1 tornado touched down here:

Rainwrapped tornado near Oskaloosa Iowa. July 19 2018. Photo by Ethan Schisler

We followed the storm into Southeast Iowa as it cycled through an outflow dominant stage. It would become mostly a bowing complex at this point with widespread damaging winds into Northern Missouri and Western Illinois. Near Keosauqua, Iowa we core punched the supercell and got extremely close to a circulation that had developed. NWS Quad Cities surveyed an EF1 tornado in the area, Cory and I managed to experience severe 70-80 mph winds for a solid 5 to 10 minutes. We never gained visual on the tornado although it was likely nearby.

We were able to decompress outside of Burlington, Iowa and enjoy one of the best sunsets I’ve personally ever seen with some awesome stormscapes to boot. Here are some images from that:

Mammatus at sunset near Burlington, IIowa. July 19, 2018. Photo taken by Ethan Schisler

Mammatus near West Burlington, Iowa. July 19 2018. Photo taken by Ethan Schisler

Mammatus near West Burlington, Iowa. July 19 2018. Photo taken by Ethan Schisler

Overall this was a very successful storm chase. Cory and I were able to visually confirm at least 5 tornadoes from Prairie City, Iowa down to Oskaloosa, Iowa. The 2% tornado risk more than verified with a tornado outbreak occurring with as many as 23 tornadoes confirmed across Central/Southeast Iowa on July 19th 2018. Here is some information from NWS Des Moines on the event:

EF3 tornado track near Pella, Iowa

Tornado tracks from Pella, Iowa cyclic supercell

SPC Storm Reports:

SPC reports for the day.

 

 

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