The problems with the clouds filter in photoshop is one I've been dealing with. But I find that by combining additional filters in other layers blended together you can get some very specific results.

I think the part of my method that I like the most is that I can manually paint one of the layers to adjust things with a great deal of certainty.

For these mountains in particular a barley opaque layer with a large blob of white on a layer with the blending mode of Overlay, or Screen will have the effect Si Lam is looking for.