A light or even moderate north-westerly regime often has little impact on the conditions close to Fiesch. However, it reinforces both the Grimselschlange to the east and the flow up the main Rhône valley to the west, presenting challenges for pilots attempting flights beyond the local area. A stronger airflow from this direction is more problematic: you may only discover you are a lee behind Eggishorn when you climb out, there may be a sidewind disturbing the thermals at Bellwald, sudden windshears anywhere to the east of Münster, and vicious turbulence to the west of Visp.
The picture above was taken on 13 July 2013, looking north-east, on my way back from Brig towards the Aletsch area. The slant on the clouds from left to right illustrates not only the significant north-westerly airflow, but also how winds from this direction typically increase with height, unlike the Bise, which is more notorious for its effects at low levels.
My account of my flight shows how it was affected by the local airflows to be expected in a north-westerly, but half a dozen pilots completed the classic 200k FAI triangle that day!