Do you think you would have reacted differently during tornado season? (I'm not sure when that is, but I am pretty sure December isn't in it, or at least was not before the storms of 2011.)

I think it is also worth pointing out that merely having sirens, and the information network capable (for the most part) of setting them off when and only when there is a significant risk, is well within about 90% of being as good as one should reasonably expect: if that is the most information you can get in the moment, how, rationally, should you respond, if not by seeking cover?

On the other hand, it is quickly counter-productive to set off the sirens for every mildly elevated risk, as it conditions everyone to be skeptical. Unfortunately, current social dynamics, which blame and punish anyone who makes a decision to not raise the alarm prior to something bad subsequently happening, is guaranteed to bring about this skepticism.