Skywarn is a program designed and developed by the National Weather Service (NWS), to help train and organize volunteers to help track and report the effects of severe weather. In simplest terms, the volunteers are not weather chasers, they are weather spotters.
Every year, severe weather such as thunderstorms, floods, and tornados cause millions of dollars worth of damage, and unfortunately loss of life. The NWS needs more information on what kind of weather conditions are happening while they pair that with radar and satellite imaging so that they can refine their monitoring and alerting criteria to give more of an advanced warning.
Additionally, some areas are too far away from the radar site and the radar beam may be over 5000 ft above the area. This means that the radar will not always see things like hail or tornado like activity, which is why the NWS relies on trained spotters to give a visual report of these things.
Every year, usually just before spring time, the NWS hosts hundreds of training classes all over the US and even online. To become a trained spotter, all you need to do is attend one of these training classes and sign up to be a spotter.
You do not need to be an amateur radio operator, however it does help. Communities all over the US need people like you to volunteer your time during moments of crisis. This is just one way that your personal efforts can make a difference, and it can even be done from home.
For more information on Skywarn, visit the NWS Skywarn page to learn more and find a training class near you.