The Commercial Mobile Alert System (CMAS) is the system interface to the Wireless Emergency Alerts (WEA) service that wireless carriers are rolling out across the nation in 2012. CMAS is a partnership between FEMA, the Federal Communications Commission (FCC), and wireless carriers, to enhance public safety. The rules for CMAS are published by the FCC at 47 CFR 10.

CMAS allows public safety authorities to use FEMA’s IPAWS Open Platform for Emergency Networks (IPAWS-OPEN) to send geographically targeted, text-like Wireless Emergency Alerts to the public. WEAs will relay Presidential, AMBER, and Imminent Threat alerts to mobile phones using cell broadcast technology that will not get backlogged during times of emergency when wireless voice and data services are highly congested.

CMAS/WEA complements the existing Emergency Alert System (EAS) which sends warnings to television and radio via broadcast, cable, satellite, and wireline communications pathways.

Here's the link to the latest info from the NWS on this service: Wireless Emergency Alerts
And an additional link on the same subject: CTIA Info

Note: There are several TV/Radio stations and commercial ventures that offer severe weather notifications directly to your cell phone. Some are free and others charge a nominal charge for their service. We make no recommendations for any of these services.