It is well known that weather models don’t predict right temperatures in mountains.
Weather models include just a coarse orography model. This is one of the reasons why in mountains global models are pretty wrong except if by chance you live at one of the model altitudes. This sketch of the model grid used by Meteo Swiss may help you understand the temperature discrepancies in mountains:


In mountains it is better to rely on high resolution models.
To give an idea of the resolution effect of model:

If you select Sounding, you see the gap between the real altitude and the model altitude.


At Les Menuires you better use AROME with 1.3 km resolution and much better Meteoblue in the local forecast panel (this consensus model of this Swiss company is taking into account the effect of the real altitude of the location).