[chris (OP)]

The jetstream, which we've also discussed here in the past, determines weather patterns in Europe (and elsewhere).

Reports suggest that it's showing a tendency to develop more pronounced ripples or undulations, and that these are driving more frequent episodes of extreme weather in Europe.

So where are these ripples coming from?

[evan_au]

The jetstream has always wandered - it's current location featuring often on US weather reports.

It's location follows the boundaries of Earth's convection cells - and like all weather systems, it is turbulent and chaotic.

There are some suggestion that as the Arctic Ocean loses its ice cover, there will be reduced temperature difference between the arctic and equator, the convection cells will weaken, and the jetstream will meanderings will become more extreme...
See: https://en.wikipedia.org/wiki/Jet_stream#Longer-term_climatic_changes