The tornado continued to our NW and N as it began to rope out. The trees and poor contrast masked our view of the new mesocyclone to the N of the tornado. As we moved back E to the hwy 33 and US 83 intersection, we guessed that the viewing time on the storm would be quite limited near the Canadian River bridge on the edge of a large road hole. So, we opted to reposition to the E. It turns out the second (larger) tornado developed about the time we made this decision, about 6 miles to our N, and we missed it. I feel like it was a boneheaded mistake that followed a very good forecast.