ChaserCentral

Creston Iowa Tornado (A look back Jeremy Degenhart)

by on Mar.25, 2011, under Storms

Wow. Incredible chase day in Iowa, culminating with a beautiful tornado just west of Creston, Iowa.

Chasing isn’t really what people think. Chasing is 95% forecasting, driving to target, revising forecasts, and staying just ahead of storms until the opportune moment. Often, failure is as thin as being 5 minutes too late.

Yesterday, there was about a 20 square mile patch of Iowa, that, for 3 minutes, was the site of a photogenic tornado – the only photogenic tornado of the day. 20 square miles. 3 minutes. That’s the difference between success and failure.

Forecasts had been looking great for some time before yesterday morning, and I decided to go into work a bit before 5 AM to get some time in before leaving at 9. I met up with Mike Brady , and we headed west.

Main concern was a strong capping inversion at 800 mb that could’ve limited convective development until too late in the day, as well as limited moisture returns. However, with the wind fields looking fantastic, strong shear, large curved hodographs, sufficient CAPE (above 1500 J/kg), and a dryline/warmfront convergence zone to play with, we decided that it was worth a shot. Mike’s original target was Red Oak, IA, while mine was Osceola, IA.

We met up with several chasers at a truck stop just east of the Nebraska border, east of Nebraska City. Cells were already popping, and moving across the river at 60 mph. We started retreating northeast, trying to stay ahead of the storms.

As the line of storms started blowing up, we noticed that as soon as they hit the warm front, they would become tornadic for a while, then weaken. The first storm we got on definitely did so…we spent about 20 minutes less than a mile in front of what turned out to be a nearly mile wide EF2 tornado – that we couldn’t see. Classic HP supercell, and the rain/hail wrapping left the tornado completely invisible. If you’ve never driven through a town with the tornado sirens screaming, and a monster area of rotation behind you…you haven’t lived.

We gave up on that cell when we noticed the next cell to the south becoming tornadic…as soon as we got to the town of Creston, a nice area of circulation became apparent. We watched this area for a few minutes, then decided to head east to stay ahead of the cell. About 300 feet down the road, we heard Brandon Sullivan screaming into the radio…”Funnel over Creston! Cone funnel over Creston!” I looked in my rear-view mirror, and, sure enough, a beautiful funnel was sitting right behind us. I flipped a uie, got to the side of the road, and Mike filmed the tor from the shoulder.

That was the last gasp for the storm…it became outflow dominant and linear soon after that. We got on another cell, saw a nice wall cloud and funnels, and then went and got our celebratory steak dinner at the casino north of Osceola.

All in all, it was a huge success. Both Mike and I forecast the location of a tornado within 20 miles or so, got in great position, and got great footage. We also were able to sell the footage to Good Morning America, the Today Show, and CBS…also would’ve sold our live stream to the Weather Channel, but we lost data connection.

And, it’s only March…just wait til May!

Write up by Jeremy Degenhart


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