switch to velocity image

This radar image is from the approximate time the photo was taken.  The approximate location of the photographer is shown.  Notice that just south of the core of the storm, there are a few pixels of weak reflectivity (in green).  This is known as the weak echo region, and is a sign of a strong updraft in the storm.  Since tornadoes typically develop at the base of an updraft, this also marks the location of a potential tornado.