I was just ahead, behind or alongside TS last December and January. At 4800 meters it might be quite comfortable, might be snowing with wind, will certainly be absent sufficient oxygen, and will probably change rapidly when least convenient. Prepare for freezing temps and occaisional snow squalls and you're likely to be pleasantly surprised. Most days.
Oh, and don't forget to watch for intermittent torrential downpours. It's a wonderful part of the world, with sights you've never seen elsewhere. Don't be scared off by the potential for foul weather.
Hope that helps.
Mark
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