Talk with the local shops (especially Great Basin). There is a lot in the area for ever level of riding. I actually hit up Centennial Park in Carson City this weekend because it had an 80% dry ride report. Was actually a nice ride and quite a bit of fun.
Eh... riding in 50degree weather aint so bad. You end up working hard enough with the climbing that we have around here that you get warm pretty quickly. I would just see what trails are decently dry (read the east side of town) and go ride. Stuff on the north side of hills and stuff in gullies and stuff will still be wet/snowy/etc.
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