I've seen those clouds before both where I live now in Washington and where I used to live in Tucson, Az. Those kinda clouds mean there's gonna be a hell of a thunderstorm briefly, usually if you see those kinda clouds, you're in a thermal, which also means that there's a pocket of differentiated air in that spot. Within minutes, clouds will absorb this thermal and HUGE thunderstorm proceeds to happen. I almost got struck by lightning when I was standing under a thermal, most surprisingly enough... twas only 200 feet away.

Oh yeah... that last picture looks painful... for the girl^___^