Nothing new to report yet but with further testing, I've noticed that leaving from Wilhelmshaven, about 90% of the time, when I cross up into the grids (longitude) of where Scapa Flow is, the winds almost always change directly to 15 meters per seccond and all hell breaks loose (After reading the above post about the windspeed increment multipliers, it's possible that I always reach these coordinates just as the change kicks in. To test this, I'll change the windinterval or whaterver that number is a little and see what happens). I think I've narrrowed down somewhat the location of one of the weather change latitudes. What I'm going to try to do is try to drive above and below it to see if there's a line that produces a change.
It could be that the weather is set to be the same along groups of grids also. Something to consider.
This is going to be tough to really test well.