A good snowpack means quite a bit more than a good ski run. Snowpack refers to the accumulation of snow that builds up over the winter, primarily in mountainous regions, and acts as a natural reservoir for the western United States.

Instead of precipitation immediately flowing into rivers, snowpack stores water in frozen form, releasing it gradually as temperatures warm in spring and summer. This slow melt is critical for maintaining steady river flows, replenishing reservoirs, supporting agriculture and supplying drinking water during the drier months of the year. In fact, snow provides over 50% of the water supply across the western United States.

The amount, depth and condition of the snowpack matters just as much as how much snow falls. A deep, healthy snowpack that melts slowly can reduce drought risk, while a shallow snowpack or rapid melt can lead to water shortages or increased flooding concerns.

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Factors like warmer winters, more rain instead of snow and earlier spring warmth can all disrupt how snowpack contributes to the West’s water supply, making it one of the most closely watched winter weather indicators across the region.

Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.