A weatheraio service is a broadcast service which airs special weather-related emergency broadcasts and announcements. Weatheradio services may also broadcast non-weather related emergency information, such as in the event of a natural disaster, an AMBER alert or a terrorist attack. They generally broadcast on a special VHF frequency audible only with special "Weatheradio" receivers or radio frequency scanners, although in some locations a weatheradio broadcast may be retransmitted on a conventional AM or FM frequency, and some television stations broadcasting in MTS stereo transmit weatherradio on their second audio program (or SAP) channel.