Thought of a few more.
Distress Call: A frantic plea for help. Indicates the spawn of an NPC in the area who has been trapped somewhere by a small horde who will gift you with items and/or skill training upon rescue.
Distress Call (Fake): A frantic plea for help. Indicates the spawn of an NPC in the area who will attempt to rob/kill anyone who responds to the distress call.
Severe Weather Warning: An emergency storm warning. Indicates an incoming severe storm. Severe storms are able to fell trees, break unbarricaded windows, and harm anything caught outside.
Anomalous Transmission: Strange interference in the broadcasts. Not an actual broadcast, but if the player is near an anomaly they start to pick up bizarre interference on the radio. The closer to the anomaly, the stronger the interference. Interference can vary depending on the type of anomaly.
Air Strike: A notice to evacuate a given area before it is carpet bombed/nuked. Warns of the formation of craters in an area of the map x number of hours from the broadcast. Don’t be there when that happens.
Radio Chatter: Radio chatter from an unknown group. Indicates the spawn of a group of NPCs, who can be inferred to be hostile, friendly, or neutral depending on the nature of the chatter.