This satellite image with overlay shows the moment that the storm reached maximum intensity.

The city of Joplin, MO is reeling after a powerful tornado spun through a densely populated part of town on Sunday May 22nd. This image, from GOES East satellite at 2345UTC, shows the storm system moments before spawning the tornado, estimated to have struck shortly before 6:00 pm CST. Many houses, school buildings and the St. John Medical Center sustained major damage.

See it larger here>

click for even larger view