

Figure 2. Radar Doppler velocity image of the St. Louis tornado taken near 8pm local time on Friday, April 22, 2010. This image is from the high-resolution Terminal Doppler Radar (TDR) at the St. Louis Airport, located at the “+” sign on the image. Green colors denote areas where precipitation is moving towards the radar, and red and yellow colors show where precipitation is moving away from the radar. Pink colors are bad data regions. The small couplet of greens right next to reds is where the tornado was, since the tight vortex had winds moving towards the radar and away from the radar. The area marked “RFD” shows where a Rear-Flank Downdraft (RFD) was occurring behind the tornado. The downdraft hit the ground to the west of the radar site and spread out in all directions, creating a diverging area of winds moving both towards and away from the radar. An area of air flowing into the tornado on the SE side is marked “Inflow.” Thanks go to Dr. Rob Carver, wunderground’s tornado expert, for annotating this image.
Severe damage characteristic of at least a strong EF-2 tornado is apparent from this helicopter view of residential St. Louis neighborhoods taken by KMOV.
Jeff Masters
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