Painted war-zeppelins riding the bow wake of a haboob the way dolphins ride the bow wake of ships (if set in other than desert conditions, this could be a massive thunderstorm). One or two of the airships are torn to tatters by the fierceness of the storm. There's panic on the ramparts of the city as they see (through spy glasses?) the approaching raiders. As the zeppelins approach the walled city (in my vision, this is an oasis trading hub center) the raiders drop grappling hooks that snag against the walls (or houses) and the winds bring the airships down close to the ground. Raiders rappel into the city (or if the walls/houses were low enough, they just jump), fighting their way inside structures before the storm fully engulfs the area. The abandoned airships explode or set fires as they are demolished by the storm (depending on your world and how they are lifted in the air). By the time the storm leaves, the raiders are in charge of the city.
edit I realize this is very similar to the scene where Maud'Dib retakes Arrakeen. I didn't have that connection until I finished writing it. This is the steampunk version of that scene.