Originally Posted by
Kerosine
Well, it's definitely a possibility since we were approaching the Pyrenees, though I've never seen MW so pronounced at high level!
The Pyrenees isn't the highest mountain range in the world (tops out at 3404metres, mount Aneto, about 100 km from chez nous) but it's worthy of attention because it's a range than can and does can generate significant wave, turbulence and spectacular lenticular cloud on a regular basis. I've certainly been in wave at FL 300 plus going over the top of the range in the vicinity of Andorra ( near the Giron waypoint).
There's an oldish techie paper on the subject here:
http://www.ann-geophys.net/15/823/19...5-823-1997.pdf
FWIW the surface flow down here on the 15th/16th was a strong northerly, due to a low over Corsica, with a fair dump of snow on the mountains...not a nice day at ground level.