if you're watching cable TV, you won't get the break-in unless you're watching a local over-the-air channel. NBC yes, CNBC no. Fox local, yes Fox News, no. I don't think the cable companies are set up to patch in local NWS bulletins. That would be quite a trick . . . but a valuable one in tornado-prone areas and in situations like this derecho.
And of course if, like us, you don't happen to be watching TV or listening to the radio . . . no amount of warnings will have any effect.