CW3E Event Summary: 26 January – 2 February 2024

13 February 2024

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Atmospheric Rivers Produce Heavy Precipitation from Alaska to Southern CA

  • A family of atmospheric rivers (ARs) brought heavy precipitation to portions of Alaska, British Columbia, the Pacific Northwest, and California during 26 Jan – 2 Feb.

The ARs:

  • AR #1 made landfall in Oregon on 26 Jan and produced at least 2–6 inches of precipitation in portions of western Washington and Oregon.
  • AR #2 made landfall in British Columbia and southeastern Alaska on 28 Jan and produced 6–12 inches of precipitation over Vancouver Island, the Coast Mountains, the Alaska Panhandle, and the St. Elias Mountains.
  • AR #3 produced AR4 conditions (based on the Ralph et al. 2019 AR Scale) along the southern Oregon coast and AR3 conditions in coastal Northern California.
  • AR #3 brought widespread precipitation to California, including 4–8 inches of rain in the Northern California Coast Ranges and western Transverse Ranges, and 1–3 feet of snow in the Sierra Nevada.
  • All three ARs were fed from a tropical moisture source referred to as a Tropical Moisture Export (TME).


  • Rain falling on moist soils caused minor-to-moderate riverine flooding in western Washington during the first AR.
  • The greatest hydrologic impacts occurred in British Columbia during the second AR, with significant flooding near Pemberton, BC.
  • Minor flooding and several landslides were reported in Northern California during the third AR
  • This family of ARs and nearby essential atmospheric features were sampled by the NOAA and the 53rd Weather Reconnaissance Squadron as part of the AR Recon field campaign.

Click images to see loops of West-WRF IVT/IWV analyses and forecasts

Valid: 0000 UTC 26 January – 0900 UTC 2 February 2024














Summary provided by C. Castellano, S. Bartlett, J. Cordeira, P. Iniguez, J. Kalansky, M. Steen, and S. Roj; 13 Feb 2024

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