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WSR-74 radars were Weather Surveillance Radars designed in 1974 for the National Weather Service. They were added to the existing network of the WSR-57 model to improve forecasts and severe weather warnings. Some have been sold to other countries like Australia, Greece, and Pakistan.
Contents
Radar properties
There are two types in the WSR-74 series, which are almost identical except for operating frequency. The WSR-74C (used for local warnings) operates in the C band, and the WSR-74S (used in the national network) operates in the S band (like the WSR-57 and the current WSR-88D). S band frequencies are better suited because they are not attenuated significantly in heavy rain while the C Band is strongly attenuated.
The WSR-74C uses a wavelength of 5.4 cm. It also has a dish diameter of 8 feet, and a maximum range of 579 km (313 nm) as it was used only for reflectivities (see Doppler dilemma).
History
The WSR-57 network was very spread out, with 66 radars to cover the entire country. There was little to no overlap in case one of these vacuum-tube radars went down for maintenance. The WSR-74 was introduced as a "gap filler", as well as an updated radar that, among other things, was transistor-based. In the early 1970s, Enterprise Electronics Corporation (EEC), based out of Enterprise, Alabama won the contract to design, manufacture, test, and deliver the entire WSR-74 radar network (both C and S-Band versions).
WSR-74C radars were generally local-use radars that didn't operate unless severe weather was expected, while WSR-74S radars were generally used to replace WSR-57 radars in the national weather surveillance network. When a network radar went down, a nearby local radar might have to supply updates like a network radar. NWS Lubbock received the first WSR-74C in August 1973 following widespread attention from the Lubbock F5 tornado of 1970.
128 of the WSR-57 and WSR-74 model radars were spread across the country as the National Weather Service's radar network until the 1990s. They were gradually replaced by the WSR-88D model (Weather Surveillance Radar - 1988, Doppler), constituting the NEXRAD network. The WSR-74 had served the NWS for two decades.
Twelve WSR-74Cs still have not been decommissioned and, of those, seven remain in active use today. The last WSR-74C used by the NWS was located in Williston, ND, before being decommissioned at the end of 2012. No WSR-74Ss are in the NWS inventory today, having been replaced by the WSR-88D. Some of these radars are in commercial use.
Radar sites in the US
WSR-74 sites include the following two categories: