Weather alerts are going high-tech. Now, your smart phone can warn you about tornado, flash floods, and other warnings. You don't even have to sign up. Cell phone towers in your area will automatically send them them to you. National Weather Service Meteorologist Nick Peetro says the new alerts aren't meant to replace traditional sources of weather information.

"It's simply a bell-ringer to let people know that something's going on. Hazardous weather event, tornado warning, flash flood warning, something like that. then, folks can go seek other information from other traditional sources like television, radio, NOAA weather radio or the internet."

Peetro says the technology is similar to SMS text messaging. This is like text messages but doesn't work the same way. On some phones it will show up among your text message, on other phones it may show up as a banner. It could depend on your particular device, or your service provider. But it is very similar to text messaging though."

The National Weather Service says cell phone towers nearby will recognize that your phone is in a warning area. "And then they send out a broadcast to essentially all phones within range of the cell phone towers," says Peetro, "If your phone picks up a signal from the tower [sending the message] you are essentially within or close to the warning area."

Peetro says the messages won't count against your mobile phone plan. You can opt out if you don't want to receive them. "This is totally free, unrelated to text messaging rates or services. But this is available only on fairly newer phones. People do not have to opt in, but individuals can opt out if they choose to not receive the warnings."

the devices will also receive Amber Alerts and Presidential Alerts.