Oz, theres some more Asperatus cloud here - are they the same as Mammatus?
Whatever the case they certainly do look a bit freaky.
Cheers.
Undulatus asperatus (or alternately, asperatus) is a rare, newly recognized cloud formation, that was proposed in 2009 as the first cloud formation added since cirrus intortus in 1951 to the International Cloud Atlas of the World Meteorological Organization.[1] The name translates approximately as roughened or agitated waves
Originally posted by GogoVicMorrow
reply to post by OzWeatherman
Thank you, I think that's it.
What I saw was much more uniform though, which made it look very unnatural.

A derecho (from Spanish: "derecho" meaning "straight") is a widespread and long-lived, violent convectively induced straight-line windstorm that is associated with a fast-moving band of severe thunderstorms in the form of a squall line usually taking the form of a bow echo. Derechos blow in the direction of movement of their associated storms, similar to a gust front, except that the wind is sustained and generally increases in strength behind the "gust" front. A warm weather phenomenon, derechos occur mostly in summer, especially June and July in the Northern Hemisphere. They can occur at any time of the year and occur as frequently at night as in the daylight hours.