|Warnings:||Tornado||Severe Thunderstorm||Flash Flood||[/10]|
Base Reflectivity images are taken at various elevation angles (tilts) during each volume scan. The Base Reflectivity image on this page is from the lowest (1/2° elevation) scan. This scan is excellent for surveying the region around the radar to look for precipitation. A value of 20 dBZ is typically the point at which light rain begins.
While Base Reflectivity offers a quick look to "see what's out there", Composite Reflectivity can reveal important storm structure features and intensity trends of storms. This is important because often during the development of strong to severe thunderstorms, rain-free areas (or areas with light rain) develop as a result of strong updrafts.
(Information Source - National Weather Service)