Thanks Rivergirl and Pete
Really wish I had of been closer to it though to see the structure! I was amazed when I saw evidence of a shelf like structure at the base of the storm. This was a supercell wasn't it? There were quite a few reports of rotation from underneath the storm?
Also, on a side note, does anyone know what causes the bright light to shine above a shelf cloud? Is it due to refraction of sunlight from above the storm?
Cheers, Cam