Answer:
Brown rabbits with a brown coat are able to camouflage from predators more easily in non-winter environment whereas white rabbits will be able to camouflage from predators more easily in the winter environment. The brown rabbits would be easier to spot in the winter hence selected against while the white rabbits would be easier to spot in the non-winter seasons hence is selected against.
If warmer temperatures last longer into the fall and average temperatures are getting warmer, I would assume that there is less snowfall in the winter. Hence brown rabbits are less prone to predation and would be slightly higher than normal (normal refers to expected amount when brown rabbits are selected against in the winter) than the population of white rabbits during the winter.