Radar images from April 13th, 2006.   Click on images for larger view.

WSR-88D radar reflectivity images of the Iowa City tornadic supercell thunderstorm at 624, 629 and 633 pm.  The scale is on the left in each figure.  Warmer colors indicate higher intensity and cooler colors indicate lesser intensities.
WSR-88D radar velocity images of the Iowa City tornadic supercell thunderstorm at 624, 629 and 633 pm.  The scale is on the left in each figure.  Green shades indicate motion toward the radar and red shades indicate motion away from the radar.  The radar is located to the east (right) on the image.  A counter clockwise circulation (called a mesocyclone) is apparent just south of Iowa City at 633 pm where the green (toward the radar) and red (away from the radar) are adjacent to each other.
Reflectivity image at 624 Velocity image at 624
Reflectivity image at 629 Velocity image at 629
Reflectivity image at 633 Velocity image at 633

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.