A nationwide system of extreme weather and other emergency alerts is set to go live this month on all major US carriers. The wireless emergency alerts (WEA) system is a free location-based service that sends short texts to subscribers who are currently in areas experiencing tornadoes, flash floods, earthquakes, or other disasters. AT&T, Cellcom, Cricket, Sprint Nextel, T-Mobile, US Cellular, and Verizon Wireless are all participating; Sprint began testing its system late last year.

When the system goes live, customers will be automatically signed up to receive three types of text: presidential alerts for national emergencies, AMBER alerts for missing children, and the aforementioned weather alerts, although they can opt out of all but the presidential messages. In some cases, users may need to update their phones to accept the specialized text messages; more information is available on the CTIA's site.

For the most part, the texts will simply alert readers to the situation and urge them to seek more information using radio, web, or television; in particularly dangerous situations, they might include instructions like "seek shelter immediately." This alert system, a collaboration between carriers, the National Weather Service, the Federal Emergency Management Agency, and other government organizations, isn't meant to replace any of the other warning methods, and it's good to see emergency services utilizing a widespread and (almost) always-on communication network.