Snowbelle city is the location of the 8th gym in Pokémon X/Y. I'm still very early in the story, only at Geosenge Town. Most of Lumiose City is still blocked off for me due to a "blackout", which cuts me off from accessing Routes 13, 14, 16,. I attempted to take Route 4, head through Santalune City, and take Route 22. However, I cannot get to Route 21 because I'm stopped by an NPC at Victory Road when I try to exit in that direction telling me that I'm essentially too low level for the area.
What story requirements do I have to meet to get access to Snowbelle City as soon as possible? I don't care about taking on the gym leader yet, I just want to be able to access the city itself so I can go to the Pokémon Center there (there's an NPC I need to talk to there for an event).