At first I could find nothing wrong with the tube or tire. I ran a cotton ball through the inside and nothing stuck. Then I saw something I had never seen.The rubber had worn completely off the wire bead for a 1 1/2 in span.
Then I found the hole in the tube, definitely a well defined blowout where the tube had found it's way through the rubber and wires and a little bubble burst.
Fixing the tube was no problem. I wondered if I should try to get the tire back to Nokian. I had used it for 3 severe winters and I'm guessing the wear occurred because I had let it stay a bit under inflated. Fixing this seemed like an interesting challenge so I gathered what I thought might help.
Duct tape and some silicone adhesive, in this case Shoe Goo.
I cut a piece of tape to stick to the inner side of a tire, like I was making a boot for a sidewall puncture, then slathered the bead wires over with a generous coating of silicone goop.
I sealed that in by folding over the duct tape. and let it set up for about an hour.
I went ahead and mounted the tube and tire to let it cure overnight.
In the morning, I trimmed off the excess tape and pumped it up to normal pressure.