You’re thinking about it too binary though. It affects everywhere.
But you keep saying “if location X gets a snowstorm, then it must not be happening there.” And if someone says it’s happening here, they mean zero snow.
Maybe for one region it decreases the chances by 10%… for another area they have already low chances of snow so it decreases chances by a percentage point or two. But there’s always a percentage chance the storms happen. It’s like a sliding scale and changing the probabilities.
It’s not a binary yes or no.