Tornado warning dissemination since 1948 has advanced from outdoor equipment, radio and television, and NOAA Weather Radio, to GPS-based systems. After the Super Outbreak of tornadoes in April 1974, a small network of government-operated weather radio stations, the National Oceanic and Atmospheric Administration's (NOAA) Weather Radio, was expanded to include 70% of the US. Local National Weather Service (NWS) offices were able to broadcast weather information 24 hours per day, 7 days per week on NOAA Weather Radio (NWR). NWR was expanded again after the 1994 Palm Sunday tornado outbreak in Alabama, and 97% of the US population is able to receive these broadcasts today. Outdoor warning sirens were placed in many parts of the country as part of civil defense activities because of the threat of enemy attack during the Cold War era. Along with the implementation of the CAP by FEMA, tornado warnings will become more targeted to the area in the storm-based warning, through the use of GPS technology in cellular telephones and NWR receivers.