I just installed FSXWX into V5 as I needed a real weather system for flying on VATSIM and I am experiencing the same issues. Now obviously they don't advertise that it is fully functional for V5 so understandbly there are issues. Most I've read are about the same thing, the constant and often violent shifting of the wind and turbulence at high altitude.
Hopefully a compatibility patch or some other fix is in the making!
Hopefully a compatibility patch or some other fix is in the making!