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.