Tiger leaping gorge hiking or mingyong glacier hike in December?

1) Am planning to go hiking for one and half day hike at tiger leaping gorge probably on 17 0r 18th December. Do people go hike during this time? How abt if it snows? Would it still be possible to hav a hiking trip?
2) Also plan to go mingyong glacier are 15 or 16th December. Are these possible during this time of the year? Are there any guides that will bring to see feilaisi sunrise and hike to see mingyong glacier?