Probably because being a Navy aircraft, it operates in a high humidity environment which is conducive to forming these types of clouds. Also, to photograph this, the jet needs to be going really fast, and typically very low--something you can't do freely over land, especially if you happen to slip into supersonic flight while doing the high-speed pass.
California seems awfully possessive about their views. When I visited Monterey, I enjoyed the views along the coast, but I was forbidden from taking a picture of a certain tree because Pebble Beach Resorts had trademarked the image of that tree (see it at their website). There were signs up all around the pull-off in the road saying that photographing the tree was illegal!
Slashdot Mirror
Over the ocean, there are no such restrictions.
Here's another link http://www.eng.vt.edu/fluids/msc/gallery/gall.htm for more cool fluid mechanics photos.
So, of course I had to take a picture...
(Damn! Should have posted anonymously!)