Whoa! What an ominous but awesome sky. Beautiful catch. My sister just emailed and said that they were having some weather issues near them arounnd Nashville, TN. Are you near them?
Those clouds certainly do look very threatening. We have also had some not so nice weather over the last couple of days we finally had a little bit of rain (other areas in Queensland have actually had flood warnings) then the winds arrived and have been blowing a gale ever since.