Green Sky Chaser

14 April 2011 Chase Log

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Target Area: Shawnee/Seminole, Oklahoma (Click on city names for Yahoo! maps links)

Chase Area: Seminole/Stroud, Oklahoma

Observations: one tornado, two funnel clouds, about five wall clouds, and two supercells

Distance: 350 miles

Time: 7 hours, 30 minutes

Chase Team: Jeff Makowski, Esther White, Amy Edmonds, and myself

SPC Convective Outlook: Moderate Risk (Click to see SPC products, data, and storm reports)

Chase Setup: A large trough was centered on western Kansas, with a surface low in northwestern Oklahoma. A dryline stretched through central Oklahoma, with dewpoints ahead of it in the upper 50s. Ample wind shear for supercells. Main concern was the moisture mixing out ahead of the dryline.

Blog Entries:

Chase #4 Coming Up... (before)

First Chase Of The Year (during)

Chase #4 Review: Bagged My First 2011 'Nado! (after)


Chase Log: The dryline stalled just east of I-35, and with some upper-level forcing, moderate instability, and a lack of a cap, we figured storms would form pretty much all along the dryline. In fact, I worried that the storms might line out too fast. Shear was great in the warm sector, and we figured that pretty much any storm that did form could become a supercell with the potential to produce a tornado.

With that in mind, we figured we would have just as good a chance to see supercells north of I-40 as south of I-40. Much of the area south of I-40 and east of I-35 is about the worst chase country, between trees, hills, lakes, rivers, and a bad road network. I decided to pick the area just north of I-40, but early on to split the difference and drive out east towards Shawnee.

Unfortunately, my car's cigarette lighters (necessary for charging laptops and such) decided to die on me at this point, so I had to stop at Wal-Mart in Shawnee to get new fuses, despite having recently replaced them. Afterwards I found that one of them still wasn't working, but I would be okay with just one for the time.

Back on the road, we made another brief stop at Braum's in Seminole. As we ate our ice cream, we saw a very nice tower go up just to our west, and it popped up on radar along with a number of other cells to the north. We immediately set off after the storm, as we knew that if we didn't get on the storms early, they might line out too fast.

We had some concern as we followed the storm, as there was another little cell to the south that began to interfere, but eventually our storm absorbed the little storm. We stopped on a gravel road somewhere just northeast of Prague, to watch the storm get its act together. We heard a nearly constant rumble of thunder as we watched some lightning to our north.

I ran down the road as some trees were obscuring our view of the updraft base, and noticed a slowly-rotating, ragged wall cloud. We drove north a bit, to about a couple miles southeast of Stroud.

Once again, a cell to the south began to interfere with our supercell, and I began to lose hope. After another wall cloud formed and dissipated, we were about to just head south again and aim for the next cell down the line. However, just as we started to get back in the car, we saw another wall cloud form and then a funnel cloud started to come down.

About 10 minutes later, we saw a funnel cloud go over halfway down to the ground, but the base was obscured due to some trees on the horizon, so we were not sure at first if it was a tornado. After a minute the funnel lifted above the treeline, stretched out horizontally, and then disintegrated.

The supercell at this point was tornado-warned, and things were getting chaotic. Shortly after this, we heard some people closer to Stroud reported our funnel as a tornado, and we later saw photographic and video evidence that it did indeed touch down (supposedly it damaged a restaurant sign as well). The tornado was probably about 4 to 5 miles to our northwest, and we saw it at 4:42 pm.

The storm looked like it was still growing and continuing to cycle, so we pressed on northeastward, driving mostly on Route 66. About 20 minutes after the tornado, when we arrived in Bristow (about 20-30 miles southwest of Tulsa), we had a harrowing experience with rapidly rotating rain curtains.

The supercell's hook began to wrap up almost around us, and we suddenly got blasted with a wall of rain and looked up to see the sky rotating. It was such a surreal experience, as I have seen rotating curtains of rain before, but never so fast and so close. I was almost too mesmerized to worry about our proximity to where a tornado could touch down.

The hook of the storm was chasing us at this point, but as it slid just north of us, we briefly stopped for a few photos. We gave up on the supercell as it neared Sapulpa, as we did not want to chase anything into the Tulsa metro. There was another decent-looking tornado-warned supercell just to our south, though, so we drove down on some more gravel roads and eventually saw another wall cloud on that supercell.

Of course, then the tornado-warned supercell south of this one started to look better to us, especially as we wouldn't have to fight with more rain-wrapped wall clouds and potential tornadoes.

However, almost no sooner did we drop south of Okmulgee than the southern storm weakened and the tornado warning was lifted. We figured that at this point our chase was about over, as there were multiple tornado-warned storms south of us, but they were well south of I-40 and in bad chase country. We were later sad to learn that one of these supercells produced a large, deadly, and damaging tornado that affected Tushka, near Atoka, in southeast Oklahoma.

On our drive back to Norman on I-40, we saw the setting sun light up the anvil and mammatus of one of the supercells to our south and the towering convection of a couple other storms to our north and east.


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