I too have no idea what that graph is all about, but i dont care as long as it snows.
I am back in Bansko on 2nd Feb, if this forecast is correct i will buy you a or two
Just a word of caution; yes, it's great that the current weather models are forecasting a fair amount of snow BUT we all need to pray like mad that we also get the colder temperatures with the snow so that it doesn't just thaw and melt after a few days. I'm quietly confident that the temperatures will be cold enough but then again I only interpret what the weather models are forecasting, nothing more.
I'll keep you updated as usual as the daily models develop and change.