How Weather Alerts Work

Maybe you remember hearing a long, shrill tone on your TV or radio, followed by this announcement: "This is a test of the Emergency Broadcast System . . . this is only a test" and then more about the information that would have been provided during an actual emergency.

That system started during the Cold War as a way for the president to reach all Americans during a national emergency. After 1963, it also was used to transmit state and local emergency alerts over local broadcast networks. The Federal Communications Commission (FCC), which oversees the system, required all television and radio stations to play the attention signal and test script at least once a week. And between 1976 and 1996, the system was activated more than 20,000 times, mostly for weather alerts [source: New York Times].

In 1997, the FCC gave the system a technological overhaul and a name change to the Emergency Alert System (EAS). Now the weekly test is a shorter, eight-second digital data signal produced by all AM, FM and broadcast TV stations, as well as cable systems with at least 10,000 subscribers, digital radio and TV and direct broadcast satellite providers. With digital technology, the EAS can pack more information into an emergency weather alert or other announcement, target it to a more specific area and send it out much faster.

Here's how the system handles a bad weather alert. First, the National Weather Service sends out the alert on its NOAA (National Oceanic and Atmosphere Administration) Weather Radio (NWR) signal, which uses specific area message encoding (SAME) and coding protocols similar to the EAS. Next, the broadcast stations' or systems' EAS equipment decodes the NWR signal. After that, the broadcasters can retransmit the weather warning to their audiences, perhaps as scrolling script along the bottom of the TV screen [source: NOAA].

State and local officials also can use the EAS to send emergency information, and the system works in cooperation with the Federal Emergency Management Administration (FEMA). The FCC and EAS make it possible to send a message through the station, cable system, satellite company or other participating service when it's unattended. And messages can be converted automatically into any language the station or system uses [source: FCC].

But you don't need to be watching TV to get weather alerts. You can buy a radio receiver or scanner that can pick up continuous weather watches, warnings and forecasts broadcast on dedicated frequencies by the National Weather Service's all-hazards radio network, NWR. Prices range from $20 to $200, and the units are available through electronics and sport goods stores. Depending on the model, you can choose a receiver that has:

[sources: NOAA and NWR]

Maybe you'd prefer to receive weather alerts via your cell phone or mobile device. Keep reading to find out what options are available.

Whether you're on your way to a soccer game or waiting to board a plane headed across the country, you'll want to know about problems with the weather at your destination. The easiest way to receive a bad weather alert may be on your cell phone or other mobile device. And you don't necessarily have to pay a premium for weather updates.

Application developers offer cell phone weather alerts ranging from simple weather alerts to notifications that offer broader types of emergency alerts. But media sources, such as The Weather Channel, also can provide an emergency weather alert on your cell phone, often based on reports they've received from the National Weather Service via the EAS. And even some cities are starting to offer these services.

Prices and options vary widely for cell phone weather alerts. Service availability depends on your wireless provider. While some services are free, you'll still need to pay your provider's rate for text messages. Here are some, but certainly not all, of the options:

Finally, if you're looking for weather alerts about somewhere more distant -- check out NOAA's Space Weather Prediction Center. You can sign up for free e-mails that'll alert you about comets, asteroids, geomagnetic storms, radio blackouts and more.

Wouldn't it be great if the National Weather Service could send weather alerts as text messages directly to cell phone users? That's in the works. Go to the next page to find out more.

While the National Weather Service's radio network is a great way to get bad weather alerts straight from the source, you're not always near one of the radio receivers that can pick up the emergency weather alert. And while you can subscribe to a cell phone service for emergency alerts, often the company is simply transmitting information from the EAS. If weather warnings came directly to you as text message alerts, you could receive them right away wherever you were.

The FCC and FEMA are working to make the emergency alerts that come through EAS available in that way and more. While information sent through EAS is currently only available on radios and televisions, the plan is to create a system that can send audio, video and text messages to landline phones, Web sites, e-mail accounts and cell phones [sources: NOAA and RCR Wireless News].

The FCC approved a plan in April 2008 to send emergency alerts to cell phone users. Here's how it would work. A federal agency would be appointed to create the messages and send them to participating mobile providers. (While these providers are not required to participate, T-Mobile, Verizon, Sprint, Nextel and AT&T have said they would participate.) The mobile providers would then send the messages to their subscribers. Similar to the companies themselves, cell-phone users could say they did not want to receive the messages.

The alerts could be triggered by any of these events:

Once the message-sending federal agency is appointed, the participating mobile providers would have 10 months to meet the requirements of the new system. They would, for example, be required to make the alerts accessible to people with disabilities by providing a distinct vibration cadence or sound cue to signal emergency text messages.

The so-called commercial mobile alert system (CMAS) for all Americans is required by the Warning, Alert and Response Network Act, which Congress approved in October 2006. However, a nationwide mobile alert system is not expected to be in place until sometime in 2010 [source: FCC Commercial Mobile Service Alert Committee].

For lots more information about weather alerts and related topics, check out the links on the next page.