A potent weather phenomenon known as a Pineapple Express is bearing down on the West Coast of the United States, threatening to unleash torrential rain and trigger severe, life-threatening flooding across several states.
Storm Details and Immediate Threats
The storm system, channelling a plume of warm, moisture-saturated air all the way from the tropical Pacific near Hawaii, is forecast to bring relentless, heavy rainfall from Monday through Wednesday morning. Northern California, Oregon, and Washington state are in the direct firing line, with some areas bracing for a staggering accumulation of up to 12 inches (one foot) of rain.
Steady precipitation will be most intense over higher terrain, particularly the Olympic Mountains, Coastal Range, and the Cascades. While widespread totals of two to four inches are expected, windward slopes could see the AccuWeather Local StormMax™ of 12 inches. This comes on top of last week's significant rainfall, which has already saturated soils and filled rivers, dramatically increasing the risks of mudslides and dangerous runoff.
Flood Warnings and Evacuations in Force
The situation is particularly acute in Western Washington, where multiple rivers are already at minor to moderate flood stage. The National Weather Service (NWS) has issued a slew of flood warnings, which will remain active at least through 18 December.
Authorities have placed approximately 100,000 residents in Skagit and Snohomish counties under the most urgent Level 3 evacuation orders, instructing them to 'leave now'. Governor Bob Ferguson confirmed that President Trump has authorised FEMA emergency aid for the crisis.
AccuWeather Meteorologist Alex Duffus warned, 'Several inches of additional rain this week, on top of last week's totals, can lead to renewed major flooding, including on rivers that recently crested at record levels.' He noted that river levels may continue to rise for days after the rain finally stops.
Prolonged Danger and Broader Impacts
Senior AccuWeather Meteorologist Alex Sosnowski highlighted the complex flood risk, explaining that while flooding in higher elevations can happen in just hours, the surge reaching lower, flatter areas can be delayed and last for several days, with multiple crests likely.
The region is still recovering from historic floods triggered by days of torrential rain last week, which saw families rescued from rooftops by helicopter and houses torn from their foundations. Several bridges and major roads remain washed out.
Beyond the rain, the storm will pack powerful winds, with coastal gusts up to 50 mph and even stronger blasts inland. Furthermore, a cooler air push from Tuesday night into Wednesday will lower snow levels to around 4,000 feet in passes like Stevens Pass, bringing accumulating snow to the region.
Residents across the affected states are urged to remain extremely vigilant, avoid all flooded roads, and heed evacuation orders without delay, as the threat of landslides and floods will persist long after the skies clear.
