What weather agency issues tornado warnings for the United States?

The National Weather Service issues tornado warnings for the United States.

The National Weather Service, or NWS, is the federal weather agency responsible for public warnings about hazardous weather, including tornadoes. Its local Weather Forecast Offices monitor radar, reports from trained spotters and emergency managers, and other observations before issuing warnings for their counties or warning areas.

A tornado warning means a tornado has been detected by radar or reported by observers, or that a storm has strong characteristics suggesting an imminent tornado. It is more urgent than a tornado watch. A watch, generally issued by the Storm Prediction Center, means conditions are favorable for tornadoes; a warning calls for immediate protective action.

The NWS is part of the National Oceanic and Atmospheric Administration, or NOAA, within the U.S. Department of Commerce. NOAA is the parent organization, but NOAA Corps and FEMA are not the agency that normally issues tornado warnings. The National Hurricane Center specializes in tropical cyclones, while NWS local offices handle tornado warnings.