Observation Networks

When it comes to weather, all data -- especially networks of data -- are useful. The NWS uses data from all of the following networks to fulfill its mission of protection of life and property and enhancement of the national economy:

• ASOS (Automated Surface Observation System): NWS and FAA observations from airports across the nation, taken continuously by automated instrumentation and, at some locations, augmented by human observers. ASOS is the backbone of the U.S. surface weather observation system. There are 9 ASOS units in Kentucky and 12 in Indiana (over 900 nationwide).
   
• AWOS (Automated Weather Observation Systems): Similar to ASOS and complementary to the ASOS network but generally at smaller airports. There are 11 in Kentucky and 15 in Indiana (over 1100 nationwide).
   
• NWS Cooperative Observers: Volunteers who report daily weather such as high/low temperatures, rain, snow, soil temperatures, and high/low relative humidity. These data comprise a large part of the nation's historical climate database and extend back to the 19th Century. Most cooperative observers report to their nearest NWS office only once per day, often in the morning, though observation times have varied greatly over the years. There are about 250 observers across Indiana and Kentucky, though that number changes frequently as some stations close and others open. The number of observers nationwide, currently around 33,000, has been on the decline for several years. 
   
• CoCoRaHS (Community Collaborative Rain, Hail, and Snow Network: A network of thousands of volunteers who measure rain and snow each day, usually around 7am local time. This program began in Colorado in 1998 and now has spread to the entire country as well as Canada and the Bahamas. All that is needed to participate in the program is an inexpensive plastic rain gauge from WeatherYourWay and a ruler to measure snow. Some observers also choose to report hail and rate of evaporation. We are always in need of more CoCoRaHS observers -- please consider joining today! After heavy snows shut down Interstates 65 and 75 in 2015 and 2016, snowfall observations taken by CoCoRaHS observers -- with the least expensive equipment of any of the observing networks listed here -- provided the necessary information required by FEMA to result in millions of dollars of federal assistance to several Kentucky counties that would not have otherwise been released due to a lack of established observations form one of the other official networks.
   
• Kentucky Mesonet: Established by Western Kentucky University in 2007, this is a high-quality local network of automated weather observing equipment at more than 70 sites across Kentucky, with future expansion planned. The equipment is sited to best represent the average weather and climate of the area it serves and provides the NWS with near real-time monitoring (every 5 minutes) via the network's website. Kentucky is very fortunate to be one of a handful of states to posses such a network.
   
• Consumer-grade weather stations: Though not part of an "official" network, the NWS does use personal weather station data as one of the arrows in our weather monitoring quiver. These stations, such as the Davis Instruments equipment used by WKU's White Squirrel Weather, can provide high-resolution data to assist the NWS in monitoring meso- and micro-scale weather variations that may be too small in size to be captured by one of the other networks. When transmitted online via sites such as the Citizens Weather Observation Program and Weather Underground, NWS meteorologists can use the data either in near real-time and when reviewing past weather events.

Each of these networks has their strengths and weaknesses, but when used together they provide the NWS with the data needed to meet our mission.