Describe the bug
When growing trees in a cold biome where snowfall is possible, snow may accumulate on the leaves of dynamic trees. From my observations, the trees try to grow around the snow, which often leads to the tree being stunted because its main trunk cannot expand further upward against the snow. Most often though, the tree ends up with random fallen snow blocks embedded within the leaves as the tree grows around it.

My natural intuition would assume that as the tree grows, it will displace any fallen snow in its path, so that is why I would consider this a bug.

To Reproduce
Grow a tree (partially) in a snowy biome, let snow fall and accumulate on top of the leaves of a tree, then if the tree's growth is observed while covered in snow, you will notice that it does replace fallen snow layers, and so its growth can be blocked by the snow. Note that there are cases where as the tree grows, some leaves are removed and snow can be dealt with that way, so the snow isn't guaranteed to block growth in all cases.

Screenshots

Rendering Glitches
Are you using Optifine? No.

What version of Forge are you running?(e.g. 1.12.2-14.23.5.2768)
1.12.2-14.23.5.2847