The SKYWARN Program was implemented by the NWS in the 1970's, and retains a critical role as a first line of defense for severe weather threats such as storms, tornadoes and flash floods. The National Weather Service trains new volunteers every year, and requires all storm spotters to complete the basic course every two years to remain in the program. Over 280,000 strong, SKYWARN storm spotters and storm trackers brave the elements and adverse conditions, and gather that much needed information known as "ground truth", and relay it back to the NWS. This is done most often through an elaborate system of HAM, or amateur radio networking and reporting frequencies. The organization of these individuals is normally left to municipal and/or county emergency management entities, or the local fire departments in any given municipality. The "on location" human advantage, coupled with Doppler radar, and data collected from satellite and other sources, greatly increases practical, advanced warning time, giving citizens the precious extra moments they need to safeguard their lives and property.