It’s not really complicated. Snow melts slowly and therefore more of the water that results from the melt is retained by ground sources.
When it rains the water that falls to the ground generally doesn’t have time to soak in; the heavier/faster the rainfall the less that is retained. Rainwater ends up traveling to storm water systems and ends up dumping into rivers or streams and is carried out of the region on which it fell.
Using a rule of thumb that each 10 inches of snow, if melted, would produce one inch of water, then each inch of snow produces about 2,715 gallons of water per acre. Actual amounts can vary considerably depending on whether the snow is heavy and wet or powdery and dry, so this is based on an average water content of snow.Heavy snow has high water content. 4 or 5 inches of a heavy, wet snow contains approximately one inch of water. It may take 20 inches of dry, powdery snow to equal that one inch of water. The 10=1 equation also assumes a 'perfect' snow-melt without evaporation which put some of the moisture back into the atmosphere.
Snow pack that accumulates each year in the mountains across the United States are a vital part of the hydrologic cycle. The snows that melt off each spring provide essential runoff to streams and reservoirs which recharge critical fresh water reservoirs and filters into underground which are being depleted at a rate that Mother Nature can’t keep up with.
As inconvenient as they seem, seasonal snowfalls are a crucial part of our lives. We should be thankful for them.