SKYWARN is a concept developed in the early 1970s that was intended to promote a cooperative effort between the National Weather Service and communities. The emphasis of the effort is often focused on the storm spotter, an individual who takes a position near their community and reports wind gusts, hail size, rainfall, and cloud formations that could signal a developing tornado. Another part of SKYWARN is the receipt and effective distribution of National Weather Service information.
The organization of spotters and the distribution of warning information may lay with the National Weather Service or with an emergency management agency within the community. This agency could be a police or fire department, or often is an emergency management/service group (what people might still think of as civil defense groups). This varies across the country however, with local national weather service offices taking the lead in some locations, while emergency management takes the lead in other areas.
SKYWARN is not a club or organization, however, in some areas where Emergency Management programs do not perform the function, people have organized SKYWARN groups that work independent of a parent government agency and feed valuable information to the National Weather Service. While this provides the radar meteorologist with much needed input, the circuit is not complete if the information does not reach those who can activate sirens or local broadcast systems.
SKYWARN spotters are not by definition "Storm Chasers". While their functions and methods are similar, the spotter stays close to home and usually has ties to a local agency. Storm chasers often cover hundreds of miles a day. The term Storm Chaser covers a wide variety of people. Some are meteorologists doing specific research or are gathering basic information (like video) for training and comparison to radar data. Others chase storms to provide live information for the media, and others simply do it for the thrill.