I don't know if snow affects combat abilities directly, but I wouldn't think so. However, as mentioned by Bert Preast, snow conditions (now) affect how quickly the PC, NPCs and animals tire when moving.
It can also be noted that your character's physical skills should be significantly impacted by the weight penalty from all that equipment, on top of whatever fatigue had been accumulated up to that point and while in combat. The more weight the faster your character accumulates fatigue, and all penalties are deducted from your character's physical skills when performed, so a marginally tired grand master dodger would not have much trouble dodging a 50% attack skills suffering from a 60% encumbrance+fatigue+injury penalty. On top of that, combat is dangerous, and a single case of bad luck may be all it takes to shift a significant advantage into a disadvantage or even death.
As indicated by Bert Preast, tiring your opponents to exhaustion before taking them on is the safest way to deal with them when given the opportunity. It's not risk free (an exhausted elk can still get a kick in if you're unlucky, but fortunately elks aren't prone to finish you off even if you're knocked out, unless they literally have to pass over your dead body to move from a corner they've been backed into), but it's as close as you can get.