CW3E Event Summary: 22-25 February 2025

4 March 2025

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Multiple Atmospheric Rivers Produce Heavy Rain and Flooding in the Pacific Northwest

The ARs:

• The first AR made landfall on Sat 22 Feb and produced AR 2–3 conditions (based on the Ralph et al. 2019 AR Scale) in southern coastal Washington and coastal Oregon.
• Significant inland penetration of the first AR also brought AR 2 conditions to interior portions of the northwestern US.
• The second AR made landfall on Mon 24 Feb in association with a strong low-pressure system and produced AR 1–2 conditions in coastal Washington and Oregon.

Impacts:

• At least 5–10 inches of total precipitation fell over much of coastal Washington and Oregon as well as the Cascades.
• Unusually warm temperatures and high freezing levels created favorable conditions for snowmelt and rain-on-snow during the first AR in the Cascades and interior portions of the Pacific Northwest.
• The combination of snowmelt and heavy rainfall led to significant riverine flooding in eastern Washington, northern Idaho, and eastern Oregon.
• Strong winds during the second storm caused widespread tree damage and power outages in western Washington and northwestern Oregon.

Click images to see loops of GFS IVT/IWV analyses Valid 1200 UTC 21 February – 1200 UTC 25 February 2025

Summary provided by C. Castellano, S. Roj, and J. Kalansky; 4 March 2025

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