Stormy Set-Up

Canon Digital Rebel XSi
18-55mm kit lens
ND grad filter

The road shots were all junk so I skipped right to Trinidad, Colorado
I knew we were in for a good sunset when I saw these mammatus clouds. This is really just a set-up image for the next one. Here, the clouds are reflecting a lot of blue tones. In the next image, you'll see how fast that switched to the opposite end of the spectrum... deep, deep oranges

Please tell me what you think!