The latest study, however, took a different approach. “Just because the speed isn’t changing, doesn’t mean the jet stream isn’t changing in other ways,” said Prof Paul Williams of the University of Reading, the lead author of the research.
In the opening post of this thread.
What I've read is that the jet stream is generally weakening because what drives it is the stark interface between arctic and tropical air masses.
According to VFR Only Please from what he's read.
So, which is it?