It's just an idea I proposed to National Weather Service a while back.
The general idea is for the National Weather Service to provide Lat/Lon based Weather Warning information to user's computer and allow user's computer to sound the speaker.
There could be several ways to implement this. For privacy concerned user, the user can run a daemon/service program on their computer and poll the weather server periodically. The other possibility is to have user registered with the server and have the server send out appropriate warning message only to computer that facing severe weather condition.
I suppose this can be extend to any kind of warning message. The real question is how we implement it. The RSS or tweeter feeds are possible, but that will require intelligent client software to decode the message and issues alarm accordingly.