This points the entrance downward and helps to keep water from gathering on the bottom board of the hive. And, in keeping them dry, they tend to generate a lot of water vapor in the hive in winter from normal aspiration. Cracking the top open and putting a few toothpick sized sticks will give the hive enough ventilation to keep it from turning into a dank damp environment. Your bees invested a tremendous amount of energy and resources into creating that comb and you should value and protect this asset carefully. Also protect your stored comb from mice by whatever method you are comfortable with.
Mice can destroy boxes of comb in short order.