How Can Base Velocity Data Be Used to Detect Rotation in Thunderstorms?
Circulations, small scale rotations, within thunderstorm can be detected using NEXRAD Doppler radar Base Velocity data. Thunderstorm rotations that persist over several volume scans, extend vertically throughout the storm (i.e. circulations that can be detected at more than one tilt angle of the Base Velocity products, say at both tilts 1 and 2) and are of sufficient strength are called mesocyclones. Thunderstorms with mesocyclones frequently produce severe weather, consisting of large, damaging hail (technically hail greater than three-quarters of an inch in diameter), high, damaging winds (technically wind speeds greater than 50 knots or 57 miles per hour) or tornadoes. Only about 40 percent of all rotating thunderstorms ever produce tornadoes. Base Velocity data should always be used in conjunction with Base Reflectivity, Vertically Integrated liquid, Echo Tops, and other NEXRAD and weather data products in determining the severity of individual thunderstorms. Rotations are identifi
