CW3E Event Summary: 21-23 February 2021

February 24, 2021

Click here for a pdf of this information.

Atmospheric River Brings Rain and Snow to Portions of the Northwestern U.S.

  • The AR made landfall during the early morning of 21 February over Washington and northern Oregon
  • Coastal locations in Washington and northwestern Oregon experienced AR 2 conditions (based on the Ralph et al. 2019 AR Scale)
  • More than 5 inches of precipitation fell in parts of the Olympic Peninsula and North Cascades
  • More than 2 feet of snow fell in the higher elevations of the Washington Cascades and Bitterroot Mountains
  • The combination of near-saturated soil conditions, heavy rain, and melting snow produced minor flooding in western Washington
  • Several avalanches were also reported near Stevens Pass (in addition to the planned avalanche control work)

MIMIC-TPW2 Total Precipitable Water

Valid 1200 UTC 20 February – 1200 UTC 23 February

Images from CIMSS/University of Wisconsin

Click images to see loops of GFS IVT/IWV analyses

Valid 1200 UTC 20 February – 1200 UTC 23 February






Summary provided by C. Castellano, J. Kalansky, N. Oakley, and F. M. Ralph; 24 February 2021