Here's a test I made earlier. It's just a jpeg on the skydome and a single infinite light to make up for the lack of dynamic range found in a jpeg. I set the infinite to be coming from the break in the clouds, towards the camera.

Obviously it hasn't baked properly, because I stopped it as soon as I was satisfied that all was working, but you get the idea.

With a grey sky the colours are rather muted, as they probably should be.

Free stuff @ https://poser.cobrablade.net/