If you don't have access to a NOAA weather radio, then you can find the online audio of it here of the Oklahoma City station after scrolling the list: http://noaaweatherradio.org/. Other Oklahoma stations are from Bartlesville, Tulsa and Stillwater. The selection of stations across the country is limited, since the network is voluntarily put together.

The available networked NOAA weather radio stations are now displayed on a map with current weather advisories here: http://noaaweatherradio.org/probwwa2/

Elsewhere, the Stillwater NOAA weather station is listenable here together with a live video from out front of the OSU library, courtesy of KFOR, assuming it's working: https://www.ostate.tv/live?play=live4