A large, damaging tornado struck northern portions of the city of St. Louis on the evening of Good Friday, 4-22-11. The NWS in St. Charles has completed its damage survey and rated the tornado EF-4 intensity at its peak, in Bridgeton along Old St. Charles Rock Road. There are many locations along the tornado's path with widespread EF-2 and some EF-3 damage. The entire path length was 22 miles, and the tornado was as wide as 0.4 mile at some points along the path:
This next image is the same track map as above, with EF intensity ratings noted along the path (please note only EF2 or higher intensities are shown):
The image below is a reflectivity (rain, hail, etc.) shot from the St. Louis area radar, taken at 7:59 PM CDT, showing the tornadic storm as it approached the Champ area:
This next image is the same as above, only in velocity mode, which shows wind speed and direction. Remember, reds show wind blowing away from the radar, while greens show wind blowing toward the radar site. In this image, the radar site is located toward the bottom left corner of the image (at the light blue "KLSX" notation). The apparent circulation is circled in white:
This next series of images show the tornadic storm as it approaches and moves over the Lambert Field/St. Louis International airport shortly after 8pm CDT. The first is a reflectivity image taken at 8:08 PM CDT. The Lambert Field weather observation site is located at the red dot near the tip of the white arrow. The weather observer reported a tornado "on the ground moving East" in an observation completed at 8:14 pm CDT:
This next image is the same as above, only in velocity mode. The apparent circulation is circled in white, and the weather observing site is noted as in the image above:
A strong radar indication of a "debris ball" began to appear to the East of the airport near Ferguson on the radar image taken at 8:16 PM CDT:
The white circle just to the East of Ferguson shows the higher reflectivities that appear to be associated with a debris ball. This is structural and other debris being carried aloft by the tornado and reflected back to the radar, just as rain or hail would normally be reflected.
The following video is multi-part. First it captures a tornado produced by the same storm near Weldon Spring, well to the West of Champ, along I-64 (time 0:00-1:30 on the video). This particular tornado dissipated at some point before reforming just West of Champ, where it remained on the ground across northern portions of St. Louis. You next see footage of the videographer(s) driving East into St. Louis toward Lambert airport. You can't really see the tornado, but you can see power flashes as it causes damage (1:31-2:08 on the video). Finally, you see video of the damage at Lambert airport:
A raw video of aerial damage footage can be seen here.
The following photos show the extensive destruction caused by this tornado:
Believe it or not, no deaths and no serious injuries were reported as a result of this tornado. Definitely a strong testament to the success of the early warning system that performed flawlessly across the area during this event.