A weather phenomenon known as the ‘Pineapple Express,’ originating near Hawaii, is set to bring heavy rain and deep snow to a large portion of the Northwest and California in the coming days. Meteorologists from AccuWeather are warning of major flooding, avalanches, strong winds, and travel delays as this atmospheric river brings significant moisture into the region.
The Pineapple Express, already visible on weather maps, will usher in a range of hazards over the next few days, marking a stark contrast to the dry weather experienced in January. Areas in the Pacific Northwest not directly impacted by the atmospheric river can expect accumulating snow, with some locations seeing snowfall for the first time this season.
Northern parts of California are expected to bear the brunt of this weather event, with heavy snowfall and rain forecasted. Cities like Redding and San Francisco could receive a month’s worth of rain from this event alone, leading to potential landslides and travel disruptions in rugged terrain.
AccuWeather meteorologists are predicting several inches of rain in the northern third of California and parts of southwestern Oregon, including urban areas like the San Francisco Bay Area and Eugene. Northwestern California and the northern Sierra Nevada mountain range are likely to experience the heaviest rainfall, with some areas receiving up to 12 inches of rain.
In the Sierra range, substantial snowfall of 3-6 feet is expected, particularly above 7,000 feet, making travel extremely difficult. Gusty winds in western Nevada could cause localized damage, adding to the challenges posed by the storm.
While the worst of the Pineapple Express is anticipated to diminish by Tuesday night, another storm carrying moisture is expected to arrive later in the week, potentially bringing more rain and snow to the region. The focus of precipitation is likely to shift towards Southern California, offering relief from recent fires but posing a risk of mudslides and debris flows following heavy downpours.
As the Pineapple Express swerves away from directly affecting the northwestern regions of Oregon, western Washington, and far southwestern British Columbia, Canada, a surge of frigid air from the Arctic coupled with Pacific moisture could result in the accumulation of snow outside the mountainous areas, caution winter weather specialists at AccuWeather.
“While Portland and Seattle have not yet seen any measurable snow this winter,” noted Danco, “that pattern appears set to shift over the upcoming weekend and into the following week.” Anticipate up to an inch of snowfall in the Emerald City, with a slushy dusting possible in Portland. Meanwhile, over two million individuals in the Vancouver metropolitan region in Canada will need to ready their snow removal equipment, as a substantial 6-10 inches (15-25 cm) is predicted by Monday night. Significantly higher snow totals are expected in the neighboring mountains, potentially affecting travel through the mountain passes.
In the low-lying areas, it has been more than a year since the last measurable snowfall. “Portland’s most recent accumulating snowfall occurred on January 13, 2024, amounting to 1.6 inches,” pointed out Danco. “Seattle experienced its last measurable snow on March 3, 2024, totaling 0.3 of an inch.” The historical average snowfall for a winter season is 6.3 inches in Seattle and 4.3 inches in Portland.
While Vancouver typically receives more snow during the winter compared to its counterparts in the northwestern United States, it has been over 70 days since snow accumulated there, dating back to November 19 when 1.6 inches (4 cm) blanketed the area.
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