Tuesday, May 10, 2011

5/10 - 11:30am CDT - We Were Next to a Tornado Last Night!?

We're a little shocked and humbled this morning in South Dakota. Last night when we arrived at our hotel in Murdo, SD, veteran storm photographer Daniel Shaw rushed out to meet us saying he had to show us some photos. What he showed us was a set of pictures containing a rope tornado illuminated by lightning that was on the ground just yards from his position late last night. The tornado actually crossed the road 15 to 20 yards ahead of him and he was understandably shaken up. The kicker in all of this is that we were only a couple hundred yards behind Daniel when this happened near Philip, SD last night. He knew full well that we were right behind him based on our live updating position on the Spotter Network and that's why he came out to meet us. Our leader Todd and I remarked during the chase that we could see a wall cloud during the lightning flashes, but there was no sign of a tornado. We then stopped to get out of our van and were met with winds of 60 mph and higher from the west, which seemed very odd. The abrupt stop to that wind just seconds later added to the mystery. But we now have our answer... those winds were from the outer circulation of a tornado!


The strange thing in all of this is that the velocity couplet, or focus of rotation in the storm, was about three miles east of the road we were on, yet the tornado crossed the road heading the in the complete opposite direction, east to west, of the storm motion. Weird right? It seems there was a second updraft base with rotation that formed on the western edge of the storm and produced this tornado. There's also the possibility that it reached all the way down and over from the updraft base that was on the eastern half of the storm. This storm also wasn't terribly impressive on radar, meaning we we didn't think it would produce a tornado, but the ingredients were certainly there for a brief spin-up. We'll probably never know exactly how this happened, but it underscores the importance of staying vigilant even when you think you're in a safe position (we were based on radar) near a supercell.

We're traveling down to Kansas from South Dakota today in preparation for tomorrow's chase in Oklahoma or Southern Kansas. The Storm Prediction Center has a Moderate Risk (!) out for the region tomorrow and I think that's a good call based on the strong upper-level winds that are forecast to make their way through the area tomorrow. The storms that form will only move about 25 mph or less tomorrow, so chasing them will be relatively simple. Last year we chased two major High Risk outbreaks in Oklahoma and the supercells moved to the northeast at 55-65 mph, which made for a horrendously rushed chases.



1 comment:

Nick said...

Well Ryan, that's a bummer you missed seeing it. I would feel quite uneasy if the wind stopped suddenly like that and I couldnt see anything!!