CW3E Event Summary: 3-5 November 2022

November 9, 2022

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Strong Atmospheric River Brings Heavy Precipitation to Northwestern US

• A strong atmospheric river (AR) made landfall over the Pacific Northwest on 3 Nov
• The first AR produced AR 3/AR 4 conditions (based on the Ralph et al. 2019 AR Scale) in coastal Oregon and southern coastal Washington
• AR 3 conditions (based on the Ralph et al. 2019 AR Scale) were observed in coastal Washington and northern coastal Oregon, while AR 1/AR 2 conditions were observed in southern coastal Oregon and coastal Northern California
• AR 2/AR 3 conditions were also observed east of the Cascades due to significant inland penetration of the AR
• This AR produced at least 5–10 inches of precipitation over portions of western Washington and northwestern Oregon, as well as 2–5 inches of precipitation in parts of the interior northwestern US
• At least 1–3 feet of snow fell in the higher terrain of the Washington Cascades, the Blue Mountains, and the Northern Rockies
• Heavy rainfall on 4 Nov caused riverine flooding on the western side of the Washington Cascades, with multiple rivers exceeding moderate flood stage
• Strong winds on 4 Nov downed trees and power lines, resulting in numerous power outages in northwestern Washington
• This AR was sampled by the 53rd Weather Reconnaissance Squadron as the first mission of the 2023 AR Recon season, with data from 23 dropsondes assimilated into the 00Z 5 Nov GFS model run

Summary provided by C. Castellano, S. Bartlett, J. Cordeira, J. Kalansky, S. Roj, and F.M. Ralph; 9 November 2022

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