CW3E AR Update: 28 October 2025 Outlook

October 28, 2025

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Two Atmospheric Rivers to Bring Precipitation to the Pacific Northwest

  • Two atmospheric rivers are forecast to bring precipitation to the Pacific Northwest through Sun 2 Nov.
  • The first AR is forecast to make landfall over the Pacific Northwest coast this evening (Tue 28 Oct). Both the EPS and GEFS are forecasting AR1 (according the Ralph et al. 2019 AR Scale) conditions across the Pacific Northwest coasts through 5 AM PT on 29 Oct.
  • Precipitation from the first AR is forecast to fall mostly over the Washington, with the WPC forecasting the highest precipitation totals (1–2 in.) over the Olympic Peninsula and Washington Cascades.
  • The second, stronger AR is forecast to propagate across the Northern Pacific alongside a strong low pressure system and impact the Pacific Northwest from midday Fri 31 Oct through midday Sun 2 Nov.
  • There is uncertainty in the onset of AR conditions, duration of the event and timing of maximum IVT in the EPS and GEFS. ~90% of GEFS and EPS members are forecasting at least AR3 conditions over the Northern Oregon coast.
  • Precipitation is forecast to be higher with the second AR but still primarily contained to Washington and Northern Oregon. The WPC is forecasting 2–4 in. of precipitation over the Olympic Peninsula and Washington Cascades for the 72-hour period ending 5 PM PT 2 Nov.
  • The WPC issued a marginal risk (level 1 of 4; ≥5% probability of flooding) excessive rainfall outlook (ERO) over the Olympic Peninsula and Washington Cascades for 5 AM PT Fri 31 Oct through Sat 1 Nov.
  • Both the GEFS and EPS are showing an extended period in AR conditions along the Pacific Northwest coast in CW3E’s landfall tool. The EPS is showing moderate to high (~60–80% probability) confidence in this period of AR conditions while the GEFS is only indicating low to moderate AR conditions (~40–60% probability). Additionally, the EPS is forecasting a higher likelihood of AR conditions over Northern California on 4–5 Nov.

    • Click images to see loops of GFS IVT and IWV forecasts

    Valid 1200 UTC 28 October 2025 – 0000 UTC 2 November 2025

    Summary provided by M. Steen and C. Castellano; 28 October 2025

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    *Outlook products are considered experimental

    For any unfamiliar terms, please refer to the American Meteorological Society Glossary.