Three rings for the Elven kings under the sky
Nine rings for mortal men doomed to die
Seven rings for the dwarf lords in their halls of stone
One ring for the big Kahuna, surf’s up, dudes!
Hmmm, so that’s pretty obviously a shelf cloud associated with the outflow boundary of an active thunderstorm. I’ll bet the intimidation factor was even higher on the beach when the wind hit, and it suddenly got quite cold.