Rain rain don't go away

This is my first post in the weekly challenge gallery. But when I saw some of the other photos posted for this challenge I remembered that I had just the shot.

It's been so long since we have had rain I had to go back through the archives to find anything related to rain. This year has been the driest on record with only about 2.5" since Jan 1. Although the Texas Panhandle will never be confused for a tropical area our normal rainfall is just over 13" by this time of year. I took this photo near the photo hotspot of Claude, TX along the eastern part of the Palo Duro Canyon (outside of the boundaries of the state park). I saw storms developing in this area and thought it would be a good chance to get some amazing skies as well as some practice using grads which I had recently purchased.

About the photo:

Canon 5D, 17-40L @ 22 mm
f16 @ 0.4 sec, ISO 100
soft-grad (either 2 or three stops - I don't remember).

From a compositional perspective I know the foreground is not great. But hey, with skies like that who needs a foreground. I also know the upper corners are a little too dark from the grad. I might try to work this up a little more but I just did a rough draft here with an ever so slight curves adjustment / layer mask to brighten this just a tad. I masked out some of the effect of the curves adjustment on the canyon walls as the curves adjustment boosted the saturation too much. I also added a smart-sharpen layer.

I appreciate honest critiques on the composition and processing.