> I mean, yes, the sirens are technically just a warning. But they don't go off until things get really serious. If you hear them, you need to get to actual shelter as quickly as possible.

I don't live in a tornado area, but I had always assumed tornado warnings functioned similarly to other storm warnings -- a "watch" indicates elevated activity and likelihood of a severe weather event, while a "warning" indicates danger is likely and you should take appropriate action immediately to avoid danger.