The complexity of the local geography is undeniable. Deep narrows glacier valleys surrounded by high peaks create challenging flying conditions.
Strong thermic contrasts, expansive ascending airflows can result in extremely strong and rough turbulences.
Generally speaking, it is not recommended to fly in this area with altitude winds stronger than 20km/hour at 2000m, resulting in very technical conditions to fly under.
Plein Joux ends up being a safer choice as it is a rather protected flying site.