Interesting - I wonder about the
1000-ft altitude difference cited for two planes on the same southwesterly heading. I assume the upset plane was the lower plane (wake vortices sink), and perhaps the leading 'Bus was in the process of its first step-climb from FL320, passing through FL330? Timing is about right, and the extra lift needed in the climb would increase the vortex intensity. 20 nm equals about 2.5 minutes separation, so that makes sense.
EDIT - AvHerald says upset plane actually
was SW-bound at FL310(?? - also in step climb?) but indeed the event occurred at about the time the lead plane was also starting
its climb from FL320 to FL340.
http://avherald.com/h?article=4b9da5b2&opt=0