They wont know why it's in use.

They only channel the transmission. They do not repeat the transmission.

All transmissions are given from a central source and broadcast from there via participants that act as repeaters.

The broadcast alarm will sound, they will comply the founding and patch it thru but they will have no idea what the broadcast is until the actual transmission from the source is played live or live via recording.

This is the only and best way to send out a massive broadcast on all airwaves that bypasses the media in all its forms.

Technically even the NOAA group can carry this same broadcast and no one is going to question the incoming alert thru a known a weather alert channel.