A major atmospheric river is producing very heavy precipitation across western Washington today into early December 11, 2025, triggering widespread and potentially historic riverine flooding, according to the Center for Western Weather and Water Extremes (CW3E). Forecasts indicate 130–200 mm (5–8 inches) of rain over the central and northern Washington Cascades and 75–130 mm (3–5 inches) over the Olympic Peninsula through 04:00 PST (12:00 UTC) on December 12. CW3E modeling shows 15 river gauges expected to exceed major flood stage and four to surpass record levels within 48 hours.
Major atmospheric river moves into Washington State, triggering widespread and potentially historic riverine flooding. Credit: NOAA/GOES-West, Zoom Earth, The Watchers. Acquired at 18:50 UTC on December 10, 2025
The Center for Western Weather and Water Extremes (CW3E) reports that the atmospheric river (AR) currently affecting the Pacific Northwest has shifted northward over recent days, directing the most intense precipitation into western Washington.
This shift has increased both the duration and intensity of rainfall, with moderate-to-strong AR conditions — characterized by integrated vapor transport (IVT) values of 500–1 000 kg m⁻¹ s⁻¹ — expected to persist through Thursday, December 11.
Forecasts from CW3E, based on National Weather Service (NWS) Weather Prediction Center (WPC) data, indicate the heaviest rainfall will occur over the Olympic Peninsula and the central and northern Washington Cascades.
For the 48-hour period ending 04:00 PST (12:00 UTC) Friday, December 12, total precipitation is expected to reach 130–200 mm (5–8 inches) in the Cascades and 75–130 mm (3–5 inches) on the Olympic Peninsula.
Image credit: NOAA/WPC Image credit: NOAA/WPC Freezing levels have risen substantially across the region, now forecast between 2 400 and 3 000 m (8 000–10 000 feet). Nearly all precipitation is expected to fall as rain, greatly increasing runoff and the potential for major to record flooding across lowland areas and river basins of western Washington.
CW3E’s modeling, referencing NWS Northwest River Forecast Center (NWRFC) data, forecasts that 15 river gauges will exceed major flood stage and four gauges will surpass record flood levels within the next 24–48 hours.
Several rivers are forecast to rise 1.5–3 m (5–10 feet), with some gauges expected to increase by more than 4.5 m (15 feet). The Skagit River near Concrete could rise nearly 6 m (20 feet) within 24 hours, and the Skagit River near Vernon is modeled to exceed its record flood stage by approximately 1.2 m (4 feet).
NOAA’s National Water Center, in its bulletin issued at 08:00 CT on December 10, reported that life-threatening flooding is ongoing and expected to continue across western Washington.
The center warned of locally catastrophic flooding along the Skagit and Snohomish Rivers, considerable flooding extending from the Cascade foothills to Puget Sound, and potential for landslides in steep terrain. Widespread urban and river flooding was also assessed as possible throughout western Washington and into portions of northern Oregon.
Evacuation orders have already been issued for parts of the Skagit River basin, as conditions rapidly deteriorate.
Image credit: NOAA/NWS Model ensembles show that 80% of West-WRF members forecast at least 100 mm (4 inches) of rain in the Skagit basin by 12:00 UTC (04:00 PST) Thursday, December 11, further supporting the potential for historic flooding in western Washington.
Residents are advised to monitor official NWS forecasts and local emergency management updates for current warnings and evacuation information.
Subseasonal outlook indicates continued wet pattern through late December Subseasonal outlook issued by CW3E on December 9 shows strong agreement on above-normal atmospheric river activity across the U.S. West Coast during the second half of December 2025. The most pronounced signals are centered over northern and central California, with continued wet conditions also likely across the Pacific Northwest.
Between December 15 and 28, models from NCEP, ECCC, and ECMWF consistently indicate an increased frequency of atmospheric rivers and wetter-than-average conditions from Washington to central California, while southern California is projected to trend drier.
Forecast tools suggest a transition from a West Coast Ridge to a Pacific Ridge circulation pattern, supporting cool and wet conditions in the north through late December before forecast confidence decreases toward early January.
References:
1 Quick Look at the AR Presently Impacting the Pacific Northwest – CW3E – December 10, 2025
2 Key Messages for Pacific Northwest Flooding – NOAA/NWS – Issued at 08:00 CST on December 10, 2025
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Teo Blašković
I’m a dedicated researcher, journalist, and editor at The Watchers. With over 20 years of experience in the media industry, I specialize in hard science news, focusing on extreme weather, seismic and volcanic activity, space weather, and astronomy, including near-Earth objects and planetary defense strategies. You can reach me at teo /at/ watchers.news.