Man-made snow is used to get some early season skiing and snowboarding happening, to improve the quality on the existing slopes, to add a bit of length to the ski season and generally improve skiing conditions with a nice, fresh cover.
It is a common misconception that man-made snow is "artificial". In fact man-made snow is more or less the same as natural snow. "Real" snow starts as water vapour in the atmosphere. As temperatures dip, the water vapour condenses into tiny drops, or if it's cold enough, as tiny ice crystals. When enough ice crystals collect together they become heavy enough to fall towards earth (we see the collected snow crystals as snowflakes). Then if it's still cold enough they fall all the way to the ground, where hopefully they settle and form a rideable base. That’s all the snow-making machines do. If it's warm and the crystals melt they become the four letters skiers don’t like – rain. The machines don’t make rain.