Yes, we are and we try to update at least daily. Our username is tetonwyo_em. We will post about daily events in our office so you can have a sense of what we do to help prepare Teton County for disasters. We will also use Twitter as one of the many outlets for emergency information in the event of a disaster.
But, just like radio, TV, and the internet in general, systems can go down or have technical difficulties. Do not depend on Twitter as your only source of emergency information, but rather as one of several redundant backups.