Provided it can be placed into the jet stream, that "weather" phenomenon is pretty well known and stable for a time period.
Steering? Not aware of steering of any kind.
Poso "was" Navy Intelligence and seems to have quit posting about it about the time the "Rape Melania" brouhaha popped up along with his public display of political involvement.
Guiding a balloon would be like pachinko. Maybe they just launched somewhere in Canada or their property already here in the US. This thing would've been a story out over Alaska or as it came across WA, ID, and into MT, or did it just pop in from Canada?