The first national test of the Emergency Alert System will trigger warnings from Maine broadcasters at 2 p.m.

The alert system is best known for its use by the National Weather Service to warn about major weather events. It breaks in to scheduled programming on television and radio stations with an audio alert, and in the case of TV, a crawl of text across the screen.

The statewide system is tested monthly in Maine, with alerts issued to Maine Public Broadcasting network then picked up by commercial radio and television stations, according to Lynette Miller, spokeswoman for the Maine Emergency Management Agency. The system was designed to alert the public in a national emergency; however, this is the first time alert systems in all 50 states will be triggered by a national signal.

It’s not clear what the alert will be but it could suggest an emergency in Washington, D.C., Miller said. Because of that, the agency wants members of the media and the public to be aware that the 30-second broadcast is just a test.