4 May 2011
This has to be the most amazing image (I’ve yet seen) of the super swarm of tornadoes across the SE USA last Wednesday. Doppler radars are very valuable for severe storm forecasting because they can sense rotation in a storm and this allows for advanced warnings of tornadoes. These radars were not available in 1974, but in 2011 they allowed forecasters to give an average of 24 minutes warning in advance of the tornadoes.
The long lines are the tracks of the rotating supercells, and where you see red, that is the intense rotation where tornadoes likely were on the ground. As a forecaster, this image tells the real story of what is now the greatest swarm of tornadoes in a two-day period ever recorded in American history.