It is not. It’s exactly as wide as the indicator shows.
You can see, I tested a lot with this ability:
Also -tho since I was alone in thast Custom Match I couldn’t test it there but- it does not work on Unstoppable targets, at least I saw a Mei in her trait being uneffected by the enemy Mei’s Avalanche.
Also comparing Mei’s, a Tank’s trait to a Melee Assassin’s lvl 13 talent who has her own trait and different kit in general… not wise.
If you need help, maybe you can find it here:
And
I don’t see how or why.