The balloon unexpectedly burst prematurely, so the balloon came down in the Navajo Nation Tribal Lands. The last APRS position beacon that was picked up by the Ham Radio APRS network and relayed to the internet was while the balloon was still at 10936 ft. The ground elevation in that area is about 5600 ft, so the payload went a bit further than is shown on aprs.fi.
This morning, I flew up there in my Cessna, which is equipped with an APRS beacon receiver and decoder, expecting that the balloon payload would still be transmitting. Sure enough, when flying close to the last known position, I was able to receive a position packet from the payload where it landed. Using that lat/long as a waypoint in my aircraft's GPS, I was able to fly within a few hundred feet and actually visually spot the burst balloon envelope. The location is about 120nm from my home airport.
At this point, an on-the-ground recovery will require a ground party that will have to contact the Navajo Tribal Police for permission to go to the recovery site.
You can see my flight track on aprs.fi by putting WA7ARK-9 in the Track-Callsign box, and expanding the Track Tail Length to at least 3 hours.
Here is an image we took this morning showing the reminants of the balloon envelope. I'm guessing this piece is about 3 ft across. The payload is about the size of a coke six pack, so it cannot be seen in this photo...