CW3E AR Update: 3 December 2025 Outlook

December 3, 2025

Click here for a pdf of this information.

Sequence of Three Atmospheric Rivers to Bring Heavy Precipitation to the Pacific Northwest Over Next Week

Three atmospheric rivers (ARs) are forecast to make landfall over the Pacific Northwest Wed 3 Dec through Wed 10 Dec, bringing heavy precipitation (5–10+ in.) to western Washington and Oregon.
The first AR is forecast to make landfall tonight with a second moisture pulse making landfall early Fri 5 Dec, extending AR conditions over the Pacific Northwest (PNW). There is potential for ≥72 hours of continuous AR conditions in WA and OR.
A second AR is forecast to make landfall early Sun 7 Dec, but is expected to be shorter in duration (<24 hrs) than the first two ARs.
The third AR is forecast to be the strongest of the ARs, with IVT ≥1000 kg m-1 s-1 in the core of the AR. This AR is forecast to impact the PNW from Mon 8 Dec through Wed 10 Dec.
The heaviest precipitation from the first AR is forecast over the Washington and Oregon Cascades, where the Weather Prediction Center is forecasting 2–4 in. of precipitation for the 72-hour period ending 4 PM PT 6 Dec.
Precipitation from the second AR is forecast to be lighter, with the WPC forecasting 0.5–1 in. of precipitation over Western Washington and Oregon for the 24-hour period ending 4PM PT 7 Dec.
Precipitation totals are forecast to be higher with the third AR. Both the 00Z GFS and 00Z ECMWF are forecasting maximum precipitation totals of 5+ inches over the Cascades in Washington for the 72-hour period ending 4 AM PT 11 Dec.
The Northwest River Forecast Center (NWRFC) is indicating the potential for larger stream rises and flooding in Western Washington associated with the forecast heavy precipitation from the first and third ARs.