I love those mountains Fallout Ranger. I've seen many things like it in California. They're dry due to the lack of rain, but when you do get precipitation all the areas lowland soak up the rain in a few minutes leaving no evidence of it having rained yet the mountains with the high elevation get snow that remains...it ultimately looks like part of the area got precipitation and the rest got none when really just the part that got "none" just absorbed it too fast.
I can't wait to go home and take some pictures of the mountains I lived in the valley near. Looks alot like those, but more green though just as steep and also prone to snow when the rest of the area gets none. If I could somehow show you the images I have mentally you'd blow your mind, but alas I never took any pictures since I never knew I'd end up leaving one day.
Sincerely,
The Vault Dweller