The sky looks powerful enough , IMO it just needs some noise reduction as Greg mentioned already . Reducing the saturation of the blues in the sky might also work fine but it is difficult to say without seeing
Thanks Guys
I am working on a mono version, which is beginning to look quite promising
Nicely captured, if you want to make the sky more prominent then lose some of the foreground; however I like the composition as is.
Excelent; yes, black and white would definitely work