We have had (and are still experiencing) waves of storms passing through this area of the central Queensland 'Capricornia' coast, Australia. This area is a subtropical coastal environment, close to sea level.
The following picture is one I took from my the balcony outside my lab (facing east):
The storm was moving to the north (left) and that part of the sky was a featureless heavy cloud. The conditions were as follows:
Ambient temperature: 30C (86F)
Wind: strong, to the north
Conditions: Heavy rain periods, heavy thunder and lightning, about 10 minutes later, the sky cleared, temperature rose and the wind dropped to barely a breeze. Numerous cloud-to-ground and cloud-to-cloud lightning was noticed from this cloud formation.
I am leaning towards this being a 'scud cloud', but a local weather-enthusiast claims it was a weakly formed non-rotating wall cloud.
What type of cloud is this?