Weather Decision Technologies believes its newest product is the latest generation of weather radio.

Founded in 2000 by former National Weather Service meteorologists, the Norman, Okla.-based company recently launched a smartphone app that essentially acts as a personalized severe weather warning system.

The app, called iMap Weather Radio, comes as a historic tornado season continues, with more than 500 tornado deaths in the United States so far in 2011, the most in any year since 1953. More than 125 people were killed and at least 900 injured in a tornado in Joplin, Mo., on Sunday.

Southwest Virginia has not been spared, with destructive tornadoes at Pulaski and Draper on April 8 and a killer tornado at Glade Spring on April 28, part of a massive outbreak that killed more than 300 throughout the South and East.

In the event of severe weather such as Sunday's tornado in Joplin, iMap Weather Radio will automatically power on a user's phone and send three shrill tones through the device's speakers. An audio alert from the National Weather Service will play, and the user will be directed to more information about the severe weather threat.

"It was conceived really to address the problem of people not getting timely alerts if they're away from TV or if they're driving or asleep," said Matthew Piette, Weather Decision Technologies' chief marketing officer. "If you look at the number of cellphones out there in the marketplace, it's a very highly effective way of getting information into people's hands when they need it most."

More than 69.5 million people in the U.S. own smartphones, according to an April report from comScore, an Internet research company. Smartphones can access the Internet and run applications that automatically download information such as news and weather.

The iMap Weather Radio is location-based, Piette said, meaning the product will download National Weather Service alerts based on the specific area a user is in. Users can also input five alternate locations from which to receive reports.

The app is $9.99, but Piette said the company offered the product free on its May 19 launch date in light of the severe weather outbreaks in the Midwest. More than 193,000 people downloaded the app that day.

The service is currently only available for iPhones through the iTunes App Store, but Piette said the company hopes to release a version for Android phones by the end of the year.

Several other companies provide free weather apps for smartphones, including The Weather Channel, Weather Bug and Simple Weather Alert. The apps vary in how visible weather alerts are; some activate the phone's alarm, while others only pop up a notification window. They can be downloaded by searching in the iTunes App Store or the Android Market.

But what if your phone isn't so fancy?

Many news organizations provide free text message alerts to subscribers when there's breaking news or severe weather. The Roanoke Times and WSLS (Channel 10) both have text message services, and WDBJ (Channel 7) plans to begin using one later this year. Users can typically sign up by visiting the news organization's website.

National Weather Service officials urge people not to discount traditional weather radios. Because they transmit over VHF bands, the radios may be more reliable in disaster-affected areas where cell towers may have been damaged.