There are several methods to receive warning about weather emergencies. From NOAA weather radios to apps for your phone from the National Weather Service or local television station. There is also RAVE that will alert you to hazards in Johnson County.
We also have a network of outdoor warning sirens. These devices are to warn you when outside of impending weather. There is an added benefit as sometimes they can be heard inside your home but please don't depend on them in your house.