Atmospheric Rivers | Pineapple Express

• Context (IE): The recent storm that hit California was fuelled by an atmospheric river, including the Pineapple Express.
• It marks the second atmospheric river event to affect California recently, following another system that caused significant rainfall and snow in the San Francisco Bay Area.

Atmospheric River

• An atmospheric river is a long, relatively narrow band of water vapour that forms over an ocean and flows through the sky, transporting moisture from the tropics to northern latitudes.
• They are formed by winds associated with cyclones and move under the influence of other weather patterns.
• It ranges from 250-375 miles in width.
• While many atmospheric river events are weak, powerful ones can carry extraordinary amounts of moisture.

When an Atmospheric River Reaches the Land

• As the moisture-laden air moves over mountain ranges, the water vapour rises and cools.
• This cooling results in heavy precipitation that falls as rain or snow.
• Unlike traditional cold winter storms, atmospheric rivers tend to be warm.
• While snow may still fall at the highest elevations, rain usually falls on the snowpack at lower elevations.
• This rapid melting can lead to runoff, flooding, and a decrease in the snowpack needed for California’s water supply.

Uses of Atmospheric Rivers

• Replenish Water: Essential for refilling water sources in arid regions.
• Wildfire Mitigation: Provide rainfall to help extinguish wildfires.

Impacts of Atmospheric Rivers

• Causes significant flooding, especially after consecutive events.
• Trigger debris flows and mudslides in saturated areas.
• Boost snowpack levels, crucial for water supply.
• Impact global ecosystems and water balance.

Microwave remote sensing from polar-orbiting satellites has enhanced atmospheric river observations over oceans.

Pineapple Express

• The term “Pineapple Express” refers to a strong atmospheric river originating in the tropical Pacific near Hawaii.
• When the Pineapple Express reaches the West Coast, it can bring intense rainfall, sometimes dumping as much as five inches of rain on California in a single day.

It is named for its moisture trail extending to Hawaii’s pineapple region.

California It is located on the west coast of the United States. It shares its borders with Oregon to the north, Nevada to the east, and Arizona to the southeast. California has one of the largest economies in the world. It is a hub for technology, with Silicon Valley being home to major tech companies.