Sources:

1: http://iwitness.weather.com/_Rare-Roll-Cloud-Tyler-Texas/video/1729829/148597...
2: http://iwitness.weather.com/_Tyler-sky/video/1729799/148597.html?b=
3: http://www.youtube.com/watch?v=cuj2fy5RfYI
4: http://www.youtube.com/watch?v=Vw0aQ3qZ7CA
5: http://www.twitvid.com/HB1BP