Atmospheric River Brings Heavy Rains and Flood Warnings to California and Beyond

An atmospheric river, known as the Pineapple Express, is poised to bring intense rainfall and potential flooding to northern California, southern Oregon, and the northern Rockies in the coming days. Weather forecasts predict that some regions may receive between 380-500mm (15-20 inches) of rain over the next six days. The situation raises concerns about flooding and landslides as the system gradually moves southward along the western coast of North America.

This atmospheric river event follows weeks of devastating wildfires, bringing both relief and risk to affected areas. While atmospheric rivers are significant contributors to California's annual rain and snowfall, providing essential fresh water, they can also cause severe flooding and landslides when they are particularly strong. Recent studies by NOAA suggest that climate change may increase the frequency of lower-elevation rainfall from these systems across much of the western United States in the coming decades.

Originating near Hawaii, the Pineapple Express derives its name from the warm, moist air it carries across the Pacific Ocean. These systems stretch for more than 2,000 miles (3,220 km) but are only a few hundred miles wide. Although not uncommon, Pineapple Express events can become dangerous if they move slowly or traverse hard, dry land, leading to mudslides and flooding. Currently, weather fronts are advancing into North America from the Pacific Ocean, affecting regions from British Columbia, Canada down to San Francisco, California.

Alongside these developments, Hawaii is experiencing adverse weather conditions with strong winds and flash flood warnings in place. The islands are expected to receive 2-3 inches of rainfall, contributing to existing weather challenges.

The Pineapple Express is set to persist throughout the weekend and into Monday before shifting further south towards Los Angeles and San Diego on Tuesday and Wednesday next week. As the system progresses, monitoring its impact will be crucial to anticipating further weather-related disruptions.