When it starts to snow the leaves stay green, you have to back out and reload your world then the leaves start the transaction from green to the silver snow covered colour, also if you go through a portal to the nether then back again the leaves start to revert back to green even tho it’s still snowing,,, again you have to back out and reload the world for them to start the transaction to the snow covered silver leaf, I play in the natural texture pack but have tried various others with the same results.