In winter the White Mountain Road is locked at a gate just north of the Sierra Vista pullout. Snow depth may or may not allow travel up to the locked gate. Past the gate the road will be covered in some places and not in others.
When the White Mountain Road is closed, a shorter route is up Silver Canyon. In winter, the locked gate on this road is closer to White Mountain than the locked gate on the White Mountain Road.
In recent years the access road to Jeffery Mine Canyon to the west of White Mountain has seen increased use and may be useable to somewhere between 5600' and 6000'. From there it is a simple ridge run up to over 14200', with no trail, no water and four or five thousand feet of scree. I believe there was an article on this approach in Summit magazine. I've only ascended this route once, and that was in summer. (Who says mountaineers don't learn?) It only took five tries before I completed the day hike.
Early last February I drove to the locked gate on the White Mountain Road. (In early January snow had blocked the road back where it left the Westgard Pass Road. That was from a New Years storm that dropped 123" at Mammoth in 4 days.) Part of the road was dry and part covered by deep old drifts that I could only cross at night while they were frozen. I shot some pictures at dawn and went down before the snow had time to soften. View to scene here:
http://dbdimages.smugmug.com/gallery/1486688/1/71166942 The New Years storm last year was bigger than most storms one would expect any time of year. The Owens valley was filled with snow:
http://dbdimages.smugmug.com/gallery/1486688/2/79032514 It was a great New Years even without White Mountain access.
Dale B. Dalrymple
http://dbdimages.com