From a R&N post:
Here's a link to the weather blog of a University of Washington climatologist in which he analyzes the balloon path and how changing altitude into different wind directions could have steered it.
https://cliffmass.********.com/
PPRuNe doesn't like the "spotted blog" site, for some unknown reason. Here's the Tiny URL:
https://tinyurl.com/5erpsb7a