This Doppler radar radial velocity product shows 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).
Since nearly all strong and violent tornadoes are preceded by a localized area of rotation with the storm, detection of this rotation allows the NWS to issue warnings before tornadoes develop.
Doppler radar allows forecasters to see inside a thunderstorm and detect conditions that often precede the development of a tornado or indicate a high probability of damaging thunderstorm "straight line" winds and large hail.
This thunderstorm was part of the Wichita Andover Outbreak in which 55 tornadoes struck from Texas northward to Iowa. The worst tornadoes occurred in southern Kansas and northern Oklahoma, the most notable being the one that struck Andover, Kansas, killing 17 people, 13 in a mobile home trailer park. There were 308 injuries and over $280 million damage.
Choose the photo browser option from the Tracking Tornadoes subtopic to see more radar images or select another icon to view this tornado from a different vantage point.
