This is our second winter in this house and I didn't see this last year.
I can only assume that it is water that has been pulled up through the roots and then for some reason has run out this severed limb hole. I just noticed this about a half hour ago. It was not there yesterday.

This is ice by the way.
We had quite a bit of rain the day before yesterday and the temperature started dropping about 9AM yesterday from 50F to 18F this morning.
I've seen pine resin coming from injured trees. I've seen sap running from fruit trees. I have never seen this amount of fluid come from a tree in such a short amount of time either here or in the south.
Any ideas?