I wish I had taken a photo, but what is going on in a few hives is that the winter cluster is surrounded by a 'donut' of dead bees.
It is really cold here, and has been about -5 F, plus or minus for the last month and just warmed up to about freezing.
It is very common here for winter clusters to die in their winter cluster with plenty of honey available.

Any ideas what might cause this? And what to do? Flip around a few frames so they don't starve? It's too cold to open them but sometimes you gotta just do it I'm thinking?