At the Virginia State Beekeepers Meeting today, Dr. Rick Fell, while
speaking on fall and winter management techniques, recommended an upper
entrance (along with some other actions). When I discussed the technique
with him afterward, he told me that he thought it was even better just
to pull the top hive body back slightly to open a gap, as is done for
summer ventilation by some of us. This would provide the entrance
between the brood boxes.

Alan Fiala in Virginia