I'm booked on the California Zephyr the first week of Spring (last week of March) with the expectation most of the Colorado Rockies will still have lots of snow.
I've not been on that train earlier in the year than late April or later than October.
I'm also hoping the Sierras will also get a good amount of snow this winter.
I've already started checking web cams in the Sierras at Truckee, Donner Pass, and Lake Tahoe.
So far I have more snow in my yard here in Iowa than the CZ route has in California.