Here we have a southward view of a supercell, with precipitation in the right middle-ground and a wall cloud beneath the cumulonimbus (Cb) tower and anvil overhang in the background. The wall cloud produced a tornado within 30 minutes in southwest Oklahoma City.

Looking west from 5 miles away, note the supercell wall cloud. We have learned much about the nature of wall clouds in the last decade. For instance, persistent wall clouds signify a strong updraft which is capable of producing large hail, and if conditions are right, tornadoes. However, only a few cloud-base lowerings actually are wall clouds, and probably less than half of all legitimate wall clouds spawn tornadoes.

This is not to minimize the importance of wall clouds, as they are a reasonable indicator of updraft strength. The most visually-impressive examples characteristically precede the most powerful tornadoes. This ominously dark wall cloud occurred with a very severe hailstorm and several weak tornadoes.

introduction

Terms for using data resources. CD-ROM available. Credits and Acknowledgments for WW2010. Department of Atmospheric Sciences (DAS) at the University of Illinois at Urbana-Champaign.

short-lived