Mono Lake can be a great location in the winter--great light, interesting cloud formations, etc. But it is winter in the mountains, which means possibly severe weather, and you need to plan accordingly. Depending on the particular time you are there, there can be deep snow that makes getting around difficult, bitterly (even dangerously) cold conditions, or thick freezing fog. In addition to warm clothing, having a flexible attitude would be very helpful. If nature cooperates and you are able to get a sunrise shot of snow covered tufa, that's great. But if nature throws something else at you, look around for other photo opportunities--they are all around.