Velocity Product

Since nearly all strong and violent tornadoes are preceded by a localized area of rotation within the storm, detection of this rotation allows Weather Service personnel to issue timely warnings before the tornado develops. Doppler Radar Radial Velocity Product showing very strong rotation within a thunderstorm in northern Oklahoma on April 26, 1991. The rotation is centered where the bright green colors (air flowing towards the radar) are next to red colors (air flowing away from the radar).