Amid the West’s worst snow drought in modern history, several ski areas are attempting a novel approach: Storing up artificial snow and preserving it until next ski season.

Known as “snow farming,” the practice involves making snow when conditions are ideal — in cold, dry weather— and piling it two to three stories high, then covering the mound with a large, insulated mat to shield it from sun and rain. When a ski resort wants to open in the fall, it can spread the snow back over runs, rather than relying on the weather.

The technology is more common in Europe but finding a foothold in the United States as snowfall has become less reliable.…