ASOS Data
The Automated Surface Observing Systems (ASOS) program is a joint effort of the National Weather Service (NWS), the Federal Aviation Administration (FAA), and the Department of Defense (DOD). These automated systems collect observations on a continual basis, 24 hours a day. Automated Weather Observing System (AWOS) units are operated and controlled by the Federal Aviation Administration. These systems are among the oldest automated weather stations and predate ASOS. They generally report at 20-minute intervals and, unlike ASOS, do not report special observations for rapidly changing weather conditions. ASOS observations are operationally generated each hour, and special observations are provided whenever the weather changes. These special reports are generated when conditions exceed preselected weather element thresholds, e.g., the visibility decreases to less than 3 miles.