Cable TV mystery

I can sorta see why they break in for Amber Alerts, but in these days of narrowcasting and hyper-targeted cable niches why would Comcast interrupt all programming in West L.A. to beam a warning about severe thunderstorms forty miles away in northeast Los Angeles County? Couldn't a crawl along the bottom deliver the same useless information? They've also done it for flash flood watches. I'm told that "Six Feet Under" came back on in time for the show's most out-there line ever: the Nate character urged his wife Brenda to make love to her brother by saying he was "pretty sure" that Arnold Schwarzenegger and Maria Shriver are brother and sister.