The National Weather Service initially operated Weather Surveillance Radar - 1957 (WSR-57) which was built using World War II technology. This was followed by Weather Surveillance Radars - 1974 (WSR-74) and then Weather Surveillance Radars - 1988, Doppler (WSR-88D) or NEXRAD (Next Generation Radar).
NEXRAD currently comprises 159 sites throughout the United States and select overseas locations. Level II data include the original three meteorological base data quantities: reflectivity, mean radial velocity, and spectrum width, as well as the dual-polarization base data of differential reflectivity, correlation coefficient, and differential phase. From these quantities, computer processing generates numerous meteorological analysis products known as Level III data.
All NEXRAD Level-II data are available through NCDC. Data are collected and recorded in units of files, which typically contain four, five, six, or ten minutes of base data depending on the volume coverage pattern. There are 41 Level-III products routinely available from NCDC, including precipitation estimates, storm relative velocity, and echo tops.
NEXRAD Radar Resources
General information on the Radar system and products with links to technical manuals and documentation.
NEXRAD Radar Data Access
Information about Radar data access systems at NCDC, visualization tools, and decoding software.
Historical Reflectivity Mosaics for the Continental U.S. (GIS Map)
Interactive map showing historical five-minute reflectivity with station locations and GIS selection tools.
Severe Weather Data Inventory
Searchable database including the Level-III NEXRAD 'alphanumeric' point products such as storm structure, hail, tornado vortex signature, and mesocyclone detection.