A very atmospheric shot with those looming storm clouds and fascinating cityscape against the foreground waters it all works very well together. The lighting and the dusk adds a lot of impact to the shot with the city lights all lit up it makes for a very dynamic scene. Your composition is very well considered placing the emphasis on that broody sky, however, in fact I would probably have given it even more emphasis with a mere strip of water about equal to the depth of the cityscape at the base of the frame.
It is no mean achievement to place so highly in such a demanding challenge, thank you for your entry.