BALTIMORE (WJZ) — Starting in May, if you have a cell phone, odds are good you’ll get early warnings of dangerous weather.

Alex DeMetrick reports all you need to do to get the alerts is have your phone turned on.

READ MORE: Amtrak & Maryland's Leaders Break Ground On Penn Station Transformation

When weather is violent enough to send truck trailers flying, it’s carefully tracked by the National Weather Service, which issues warnings. In Maryland, those warnings will soon go out to cell phones.

“There’s a specific tone you will hear and then the alert will pop up right on your phone,” said Chris Guttman-McCabe.

The alerts will come as text messages for wide-scale threats like tornadoes or more localized dangers like the flash flood last year in Baltimore County.

READ MORE: Hogan Authorizes State Health Officials To Administer Moderna, J&J Boosters

“Water just came rushing in and she was up to her neck in water,” said one woman.

“It sends a broadcast signal out to every phone that’s in the area, so if you live in California but happen to be in Baltimore, you’ll get Baltimore’s alerts. You won’t get California’s alerts,” said Guttman-McCabe.

That means a school bus driver can get warnings on the road before anything happens, either from the Weather Service or from Maryland’s Emergency Management Agency, which links through the Internet to the towers of cell phone providers, all within seconds. There’s nothing to sign up for to get the alerts and no fees are charged for the service.

“AT&T, T-Mobile, Sprint, Verizon and U.S. Cellular are all up and running,” said Guttman-McCabe.

That gives people a running start to get out of the way.

MORE NEWS: Man Dies In Crash In Salisbury Police Chase

Besides warnings for dangerous weather, the service will also issue Amber Alerts and emergency announcements made by the president.