Here is the forecast I made yesterday morning:
And, here is where the tornadoes actually occurred (red dots):
Of course, I have mixed feelings about this. From a societal standpoint, I'm very happy there were fewer tornadoes with no one hurt. From a forecaster point of view, my ego is bruised.
What happened? I'm not sure, but I will share my speculation. The thunderstorms developed almost exactly where I forecast them. I've circled the thunderstorms in yellow. W = Wichita. Compare the thunderstorms to the "higher risk" area on the map above.
What is a "boundary"? A zone where there is a wind shift, rapid change in temperature or rapid change in moisture. They can usually, but not always, be seen in satellite imagery.