August 21, 2002, Muscatine, IA Tornado

A previously available product, Storm Relative Velocity (storm forward motion removed), is displayed on the left with lower resolution and fewer data levels. Although a rotation pattern is evident, it is not definitive enough to support a tornado warning decision, and the forecaster would have waited for another volume scan (five minutes) to confirm the signature’s persistence. On the right is the new, full resolution Base Velocity (storm motion not removed) product. With the higher resolution and more data levels, the forecaster was able to see a complete circulation pattern and had the confidence to issue a tornado warning immediately.