Who cares if it is rain or snow?
The main aim is that more foreigners can come to Bulgaria to give us their money. If there is no snow, they still will pay for the hotel, for the bars and so on.
Everybody knows that the season in Bulgaria starts in the mid January, so if you want to ski in December you should take the risk.
We say precipitation because depending on the average air temperatures at the time that precipitation can fall as rain, sleet, snow, hail, cats and dogs, frogs etc.