Pineapple Express Set to Drench West Coast With Up to a Foot of Rain, Prompting Flood Warnings
Forecast calls for heavy rainfall across Northern California, Oregon and Washington, with potential for floods, mudslides and power outages as a warm, moist plume from near Hawaii arrives.
A potent Pineapple Express is forecast to drench Northern California, Oregon and Washington beginning Monday and lasting into midweek, delivering heavy rainfall, rising rivers and a heightened risk of flooding, landslides and power outages.
Forecasters say the storm will concentrate its rainfall in higher terrain, including the Olympic Mountains, the Coastal Range and the Cascades, with two to four inches expected in many areas and an AccuWeather Local StormMax of 12 inches on windward slopes. In some locations, rainfall could add up to a foot when combined with totals from last week. Meteorologists warn that the storm’s atmospheric river could overwhelm soils and increase runoff, heightening flood risks. Duffus of AccuWeather noted that several inches of additional rain this week, on top of last week’s totals, could trigger renewed major flooding on rivers that recently crested at record levels.
Western Washington remains on high alert as rivers rise and flood warnings remain in effect at least through December 18. In parts of Skagit and Snohomish counties, tens of thousands of residents are under Level 3 evacuation orders, with authorities urging immediate departure from high-risk areas as rivers are expected to crest again. Officials have cautioned that existing flood conditions could worsen with the incoming system.
Sosnowski of AccuWeather warned that multiple rounds of moderate to major flooding are possible along short-run rivers in the higher and intermediate elevations of the Cascades. He noted that flooding in higher elevations can occur within a matter of hours, while flooding reaching lower, flatter terrain just above sea level might be delayed and could be longer-lasting, potentially lasting for several days as river crests repeat.
The storm will bring steady, intense winds across the Northwest, with coastal gusts reaching up to 50 mph and even stronger gusts inland through the northern Rockies. The combination of heavy rainfall and powerful winds raises the risk of power outages and travel disruptions, particularly along vulnerable roadways and in flood-prone zones.
In addition to rainfall, forecasters warn of a cooler push Tuesday night into Wednesday morning that could bring widespread accumulating snow across the region. Snow levels are expected to drop to around 4,000 feet in parts of the Cascades, including Stevens Pass, raising concerns about travel impacts on mountain highways and ski areas.
The weather pattern comes as authorities monitor a rapidly changing flood picture. Rivers across western Washington have already shown signs of rising levels, and officials have been urging residents to stay off flooded roads and to heed evacuation orders where issued. Flood warnings issued by the National Weather Service are in effect for multiple rivers and counties, reflecting the potential for rapid changes in water levels as the system moves inland and then exits toward the Rockies.
Governor Bob Ferguson said President Trump had authorized FEMA emergency aid to assist in the ongoing response to the flooding crisis in Washington, underscoring the federal role in supporting local communities during extreme weather events. Officials stressed that residents should remain vigilant, follow official advisories, and be prepared for possible changes in evacuation status as rivers respond to the rainfall.
Across the broader West Coast, residents are being urged to monitor forecasts closely and prepare for possible se chairing impacts, including road closures, flooded low-lying areas, and disruptions to critical infrastructure. While the heaviest rainfall will occur on higher terrain, the sheer volume of water and the rapid progression of flood crests in some locations could still threaten communities farther downstream, especially those built along river corridors that have recently seen record or near-record flooding.
As the storm unfolds through midweek, emergency officials emphasize the importance of preparedness. People living in flood-prone areas should ensure that emergency kits are ready, that property has secure drainage where possible, and that families have an evacuation plan in place should the situation require swift action. Authorities are updating river gauges and staging centers as they monitor developments and issue new alerts as needed.
In the weeks ahead, meteorologists caution that atmospheric rivers like this one can produce multiple waves of rainfall, extending the risk of flooding and related hazards beyond the initial storm. Residents across the affected states should stay tuned to official forecasts and heed guidance from local emergency managers to reduce the risk to life and property.