Here's the atmospheric physics behind the idea: Warm air expands, and naturally there is much more warm air at the equator than at the poles. Thus, the atmosphere is thicker at the equator, and the jet stream's motion is driven by the decline in atmospheric thickness as one moves in a poleward direction -- in effect, its atmospheric river flows "downhill," in Francis’s words.When I went to school, colder air was denser and warmer air was thinner. Pilots I know whose lives depend on knowing just how thick the air actually is, agree with me on this. Passing reference is made to a rather large typhoon (Nuri) that meandered all the way to the Bering Sea, up north of the jet streams usual path before dissipating. As far as I know, no one studied this very closely although it may well be that no one has published anything yet.
Keep an eye out for papers on the effect of typhoon Nuri on the jet stream.