I grew up in Montana and have spent about 2/3 of my life in Montana. However I have never seen it snow as hard it does in the Sierra Nevada mountains of California. I recall seeing snow accumulations around 6"/hour! That’s getting stuck just driving down the road levels of snow.
So if you wonder why it is wiser to fly to Vegas or Reno in the winter, this is why. Donner party FTW! As usual it’s the other drivers you have to worry about, if the road was empty it would be much easier to cross.
The other big problem is there is only one interstate going east in northern California. For most people they don’t think about the smaller state highways like HWY 50 or 88. Often HWY 50 is in much better condition than 80, it just has some exposure on the other side coming down to Tahoe.