This can limit the locations at which snow can be generated to a particular slope or elevation. It might even be necessary to create snow in one area and later move it to slopes that need additional coverage. Obviously, ski area operators have plenty to think about when they wish to make snow. Once they consider the weather conditions, there can be extensive activities preliminary to the actual snow making. Depending on the type and age of equipment, preparations could include adjustments of water, compressed air, and nozzles to optimize the quality of the 'snow', and adjusting the aim so the snow falls in the right places.
People have to be mobilized.
Compressors and pumps must be fired up. There may be activities peculiar to the slope itself. You don't just turn these babies on and off like a light switch. In some cases, the hassle and expense of making snow tonight is unnecessary, because Mother Nature will come through with plenty of the white stuff tomorrow. We can tell you when that will happen, too.