June 26, 2009 chase account

I got lucky again. TWISTEX was going to go after the setup in the northern plains. Chris and I were to meet the rest of the team in central South Dakota, but we had car problems before we even left! Thankfully, we made it well before anything happened.

Finally, a synoptic system to chase! I hadn't seen one of those since the May 15th chase. Surface winds were very good, southeast sustained at 15 kts easily. The only problem with the set up on this chase: the main forcing was a cold front. But there also was an old outflow boundary ahead of the front, and the surface was warm and moist enough, with cool enough mid levels so that storms could fire from heating to the convective temperature.

We headed west from Chamberlain, SD towards Murdo on I-90 and then went south on Highway 83 towards the SD/NE border. We saw storms had initiated far to the southwest, a supercell in fact, just crossing from CO into NE, and a few less organized storms near the NE/WY border. As we continued south on 83, more storms begain firing, but they were disorganized, multicellular, and were quickly lining out. About the time we got to the border, a tight cluster of tiny cells went up just to our west. We hoped they would coalesce into a monster supercell, but they never did. They just lined out like everything else. Thus, we decided to get east to stay in the really unstable air with great shear, hoping something would develop ahead of the line.

We made it through Valentine and headed southeast on Highway 20 when we saw a spin up on BV just to our northwest, embedded within the line. We stopped briefly to get a look at it, but couldn't see anything other than a mean shelf cloud coming our way. Without realizing it until it was too late, we stayed there too long and got eaten up by the shelf just as we left our post along the highway. We only had one road to take, so we had to just drive through it. It was a hefty downpour with strong winds. Also, lightning became quite violent. On our way towards O'Neill, we witnessed numerous CGs hit within a few hundred yards of our cars.

Despite the very suitable atmosphere for severe weather ahead of the front, no other storms developed and the line pressed east all the way across the state, clearing everything out. We stopped in O'Neill to eat and in Norfolk for the night. That was the last chase for the 2009 season of TWISTEX, and after saying some goodbyes, Chris and I headed home the next morning.

Part of the TWISTEX armada in front of the Taco Johns in Chamberlain. I thought it was funny that such a small town had one, and that we had picked a place to eat (not Taco Johns) that was right next to it such that we all parked in front of it. Ever since June 5th, I thought eating lunch at Taco Johns would bring me luck (i.e., a tornado). It worked on June 17th. However, I am only 2 for 4 on that for the season.
Shelf cloud fast approaching. Looking north.
Shelf cloud fast approaching. Looking south.
Best view of the mean shelf (also looking south). It was really cruising east at this time. Our road only went southeast, so we didn't have much of a chance of staying ahead of it by this time.

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