CW3E Winter Storm Update: 24 February 2023 Outlook

February 24, 2023

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Winter Storm to Bring Additional Precipitation to the Pacific Northwest and California

  • A period of unsettled weather will continue for the US West Coast, with a winter storm forecast to bring precipitation to Washington, Oregon, and California starting Sunday
  • A mid-level trough is forecast to move quickly through the Pacific Northwest on Sunday, bringing precipitation primarily to the Olympic Peninsula and Cascades
  • A second, stronger mid-level trough is forecast to develop over the Gulf of Alaska and shift towards the US West Coast late Sunday, bringing precipitation to locations along the Coast Ranges of Washington and Oregon, Northern California, and the Sierra Nevada early next week
  • The National Weather Service (NWS) Weather Prediction Center (WPC) 5-day QPF totals are > 1.5 inch in the Olympic Peninsula and Northern Cascades, > 3 inches along the Coast Ranges of Oregon and Northern California, and > 5 inches for the Sierra Nevada through Wednesday
  • Significant snowfall accumulation is expected in the Cascades and Sierra Nevada as a result of this cold winter storm, with freezing levels dropping below 1,500 meters in the Sierra Nevada during this event
  • This storm will provide an additional boost to the snowpack in the Sierra Nevada, which is already well above normal for the season as a result of a prolonged period of active weather along the US West Coast
  • The 00Z ECMWF is forecasting higher watershed precipitation totals (3-4inches) along the Coast Ranges of Washington and Oregon and in the northern Cascades than the GFS, while the GFS is forecasting higher watershed precipitation totals (4-6 inches) along the Sierra Nevada as compared to the ECMWF

Click images to see loops of GFS Precip and 500 hPa Vorticity forecasts

Valid 0000 UTC 26 February – 0000 UTC 3 March 2023







Summary provided by S. Bartlett, C. Castellano, S. Roj, and F. M. Ralph; 24 February 2023

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