webs1275
I doubt it's anything magnetic, more likely "just" the terrain. Before moving down here (I live not far North of Andorra) I imagined the Pyrennees were little more than a bit of a ridge but on arriving here for the first time I was seriously impressed by the terrain. The highest, Aneto is over 3400 metres and the whole ridge has some significant peaks such as the aforementioned Canigou. The range often spawns some ferocious thunderstorms, with all the associated hazards ( turbulence, icing) , and even in clear weather there can be some pretty significant Clear AIr Turbulence.