The Pineapple Express is a weather phenomenon that contributes to significant snowpack in the Sierra Nevada by bringing moisture from the Pacific.

The Pineapple Express is a type of atmospheric river that transports warm, moisture-laden air from the tropical Pacific near Hawaii to the western United States. This weather pattern can bring heavy rain and snow to the Sierra Nevada, particularly in the winter months. When the moisture falls as snow at higher elevations, it significantly contributes to the snowpack, which is vital for water storage and provides runoff during the spring melt. The Pineapple Express is often associated with mild temperatures, but its moisture delivery plays a crucial role in replenishing the snowpack in the Sierra Nevada.