Seattle – December 2, 2023
Seattle, known for its frequent rainy days, is preparing for an intense weather onslaught as a series of atmospheric river storms barrels toward the Pacific Northwest. After an unusual week-long respite from rain in mid-November, the region is set to experience a deluge of heavy rain and snow, measuring in feet, with significant implications for both lowlands and mountainous areas.
The initial storm, making its appearance after a dry spell since November 22, is expected to bring typical autumn rain to lowland areas. However, the Cascades and Olympics are anticipated to face heavy snowfall. Following closely, a second storm is poised to extend the precipitation and mountain snow well into the weekend.
Winter Storm Warnings are in effect, covering the entire expanse of the Cascades in Washington and Oregon, including crucial mountain passes near Seattle and Portland. As evidence of the impending weather challenges, chains were already mandatory on I-90’s Snoqualmie Pass east of Seattle, causing disruptions as approximately 30 semi trucks spun out on the snow-covered freeway, leading to a temporary closure.
The warnings span both storms and extend into Sunday morning, forecasting up to 2-3 feet of snow, with the bulk falling from Friday night into Saturday. Wind gusts of 40-50 mph may lead to blowing snow. Amidst these conditions, travel advisories are being issued, with FOX Weather Meteorologist Britta Merwin cautioning against weekend travel, particularly for students heading home.
Simultaneously, eastern Washington and Oregon will experience snow accumulation of 2-4 inches from Friday night into Saturday, impacting morning commutes and heightening hazards.
The weather pattern takes a dramatic turn on Sunday as warmer atmospheric river storms, influenced by tropical moisture, move in from the Pacific. This shift is expected to elevate snow levels and precipitation amounts significantly, transitioning concerns from heavy snow to intense rainfall and potential flooding in rivers and urban areas.
Snow levels are predicted to rise to over 5,000-6,000 feet on Sunday, persisting into Monday, with a subsequent surge in the “Pineapple Express” atmospheric river. This storm, tapping into warm, tropical moisture near Hawaii, is expected to raise snow levels over 7,000 feet by late Monday into Tuesday, accompanied by several inches of rain in both lowlands and mountains.
With the influx of moisture, snowmelt becomes a concern, leading to an increased threat of flooding in the Cascades. Flood Watches have been activated for all rivers originating from mountainous regions in Western Washington starting from Saturday evening and continuing through Wednesday.
As the Pacific Northwest braces for this atmospheric onslaught, residents are urged to stay informed and take necessary precautions to mitigate potential risks posed by heavy rain, snow, and flooding.