MIKE MOSS SAYS: Diane, The "full details" button opens up a more complete current observation for the selected forecast location than the icon and temperature typically shown next to the button. As you noted, the first item on the expanded list is the ICAO identifier for the airport weather station closest to the city in question. ICAO stands for "International Civil Aviation Organization." The ICAO (often spoken as "eye kay oh") has established a unique four letter code for all airports and some other aviation-related facilities worldwide.
In this case, the letter K denotes a station in the conterminous United States and the following three letters refer to the specific station, i.e. KRDU is the Raleigh-Durham airport, KEYW is Key West, KDEN is Denver, KRZZ is Roanoke Rapids, etc. Note that while most of the time the 3-letter identifier used in airline bookings and on baggage tags corresponds to the last three letters in the ICAO identifier for the U.S., that is not always the case and the 3-letter baggage and reservations IDs actually arise from a different organization called the International Air Transport Association (IATA).
Meteorologists often use the ICAO codes for listings of weather observations from airport sensor suites and for forecast model output specific to the locations of airports. For more on these codes, including a list of ICAO codes by country and a link to IATA code listings, see
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