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Measuring weather
Surface observations - observers & spotters
Standard automated systems, like the ASOS, cannot observe a number of weather features that are typically reported. These include, clouds above 12,000 feet, local visibility variations, visibility over 10 miles, snowfall and snow depth, sand, dust, smoke, hail, ice crystals or pellets, virga (precipitation that does not reach the ground), and distant precipitation. At the most important ASOS sites, automatic observations are supplemented with human weather observations, which cover many of the same variables presented elsewhere on this site. Professional observers make observations every hour, with the process beginning 45 to 50 minutes after the hour. People don't work quite as fast! Human observations serve as a quality control on ASOS observations, which may not always be accurate for a variety of reasons or which may differ just because of perspective. For instance, when making observations of cloud cover, humans make a single observation in all directions whereas ceilometers make many observations in one direction. These trained eyes are also used to create special reports in the event of special weather, like a rapid change in the weather or a tornado. At the professional level, meteorologist observers typically have at least a college degree in a related field in addition to on the job training. But even that is not enough for good observational coverage. Twice daily human observations are often recorded at numerous non-ASOS stations for record-keeping purposes by persons with minimal training. Weather forecast centers around the United States rely on weather spotters. Official weather spotters receive observation training and submit observations when requested or when significant events occur, such as heavy snowfall. Weather spotters provide observations that assist the National Weather Service in making decisions and give the professionals a truly reliable informationbase for detection and verification of weather events. Examples of weather spotters include:
Links and resources
Surface observations - observers & spotters
Standard automated systems, like the ASOS, cannot observe a number of weather features that are typically reported. These include, clouds above 12,000 feet, local visibility variations, visibility over 10 miles, snowfall and snow depth, sand, dust, smoke, hail, ice crystals or pellets, virga (precipitation that does not reach the ground), and distant precipitation. At the most important ASOS sites, automatic observations are supplemented with human weather observations, which cover many of the same variables presented elsewhere on this site. Professional observers make observations every hour, with the process beginning 45 to 50 minutes after the hour. People don't work quite as fast! Human observations serve as a quality control on ASOS observations, which may not always be accurate for a variety of reasons or which may differ just because of perspective. For instance, when making observations of cloud cover, humans make a single observation in all directions whereas ceilometers make many observations in one direction. These trained eyes are also used to create special reports in the event of special weather, like a rapid change in the weather or a tornado. At the professional level, meteorologist observers typically have at least a college degree in a related field in addition to on the job training. But even that is not enough for good observational coverage. Twice daily human observations are often recorded at numerous non-ASOS stations for record-keeping purposes by persons with minimal training. Weather forecast centers around the United States rely on weather spotters. Official weather spotters receive observation training and submit observations when requested or when significant events occur, such as heavy snowfall. Weather spotters provide observations that assist the National Weather Service in making decisions and give the professionals a truly reliable informationbase for detection and verification of weather events. Examples of weather spotters include:
- National Weather Service storm spotters
- amateur radio operators
- emergency management personnel
- law enforcement
- television and radio media personnel
Links and resources
