17 April 2011

Wild Friday Tornado Outbreak

Posted by Dan Satterfield

Hook echo on Doppler radar early Friday near Clinton Miss. The image on the right indicates wind velocities toward and away from the radar. Notice the extreme winds away from the radar, adjacent to high velocities toward the radar (just south of Clinton). Images NOAA.

The tornado outbreak on Thursday night into Friday from Oklahoma into Alabama was the worst of the spring so far. More damage was reported into North Carolina on Saturday but the states of Mississippi, Oklahoma, Arkansas and Alabama were hardest hit.

Most of the tornadoes were EF 0 to EF-2 which means winds were around 70-115 mph. You will survive if you are in a house, but a trailer park will be totally destroyed. Three deaths in south Alabama on Friday were the result of a tornado throwing a trailer 100 meters into an oak tree. Three other deaths were in mobile homes, near Montgomery, and make no mistake about it, your risk of death or injury from severe weather is MUCH greater in a mobile home.

AN EF-3 tornado near Clinton, Miss. early Friday injured 10, and produced something rarely seen on weather radar, a debris ball. A debris ball is a round radar echo caused by a tornado throwing debris into the air . They are usually only seen when tornadoes develop close to the radar site, because the radar beam gets higher with distance from the radar (the beam overshoots the debris). The NOAA Doppler (in Brandon, MS.) was quite close to Clinton.

The Birmingham area was also hard hit on Friday, with several tornado touch downs reported. The NWS in Birmingham has a preliminary summary of the damage and the strength of each tornado here.