Winter Winds Aloft

[Sleep Deprivation Chamber]

Simple question for the drivers who plow the Japan-US routes on a regular basis:

(1) Over the Pacific (Japan-USA) in which season is the wind stronger
or weaker, and

(2) In which season is the turbulence worse or better.

Thanks,

Charles Pribyl
Kanazawa, Japan

[Capt H Peacock]

In the Northern winter, the Siberian anticyclone marks an area of very cold air. To the southeast of Japan and Taiwan the air is considerably warmer and so a strong thermal wind blows almong the boundary at altitude. Because the thermal contrast is so large, these tend to be the strongest jetstreams in the World, with some recorded figures up to 400kts. This is obviously where the worst turbulence would be experienced.

[tired]

SDC - as the good Capt says, winter sees the strongest winds. As a matter of interest, we operated NRT-LHR yesterday morning and the wind at TOC (FL310) was 215kts - and it's only the beginning of winter!

Strangely enough, although it was very bumpy, I've experienced worse turbulence in much slower jetstreams - sometimes you get lucky, I suppose!