IPAWS is FEMA's Integrated Public Alert and Warning System. It combines the Emergency Alert System (EAS), Wireless Emergency Alerts (WEA), and National Weather Service Dissemination Systems. The data stream uses the CAP 1.2 protocol.
When an emergency occurs, a public safety official can use an Integrated Public Alert and Warning System (IPAWS)-compatible computer software program to send an alert to people in their community. The alert goes through the internet to the IPAWS-Open Platform for Emergency Networks (IPAWS-OPEN), which ensures that the alert was sent from an authorized source. IPAWS-OPEN then routes the alert to cell towers, radio and television broadcasters, road signs, sirens, etc..
If you want to know more about IPAWS, see http://www.fema.gov/integrated-public-alert-warning-system.
Users of this data stream are required to sign an agreement with FEMA.
Weather Message uses this data stream to provide desktop alerts of impending national, regional, and local hazardous situations.