I’ve thought of an addition to this list of things that prevented a bad tornado from being much worse: the trees had no leaves.
Seriously. Had the trees in Springfield had leaves they would have been far more susceptible to the power of the wind since the leaves would have acted like little sails capturing the wind and surely dragging down many, many more tress. These additional falling trees would have cut more power lines, smashed more cars and houses, and maybe killed someone. As it happened, many trees were spared as the wind simply blew through their bare branches.