Best Sion Diversion Airport
 

On the basis that Geneva will issue their annual NOTAM saying that it cannot be used as a 'weather diversion' airport during the winter skiing season months, we are looking for suggestions as to which airport is considered best for a diversion, if Sion is closed?

I've used LSZB Bern but it is a Cat B airport and can be weather sensitive too. Best coordinate early to get the transport in place.

Yes, Bern is very tricky too - it's 2hrs 3mins (Google Maps) to Verbier from there - but Turin seems a better option at 2hrs 30mins!

Annecy is 2:30 drive and needs special training for the few days you need to circle. But it is well connected to the autoroutes and quite friendly.

Fly a few miles east and land at Turtmann. Complimentary parking available, just taxi into mountain. Watch out for go-karts!!

I'm not sure LSGG will put out said NOTAM this year and it is extremely rare LSGS would be closed for weather in winter but it might obviously happen.
All depends on what you are flying but LSGL might be an option. Otherwise I would suggest you plan north all the way to LSZH (where you'll have full range of ground support & transport, CAT III, etc) or south , ie somewhere in Italy - places such as LIMF, LIME or LIMC.

Incidentaly I believe both Bern and Annecy are CAT C.

I have Annecy as a Cat C, Bern a Cat B :) I have had to divert from LSGS due dodgy weather. The cloud just wouldn't shift in time. Geneva said "non" (as expected) and we ended up in Bern (alternate). :)

Have a look at Payerne. It's closed on Sunday though