CW3E Event Summary: 17-22 December 2020

December 23, 2020

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Multiple storms impacted the Pacific Northwest over the Weekend and into Monday

  • The first event brought AR 1 conditions to far northwestern Washington as a decaying AR propagated down the coast from British Columbia
  • The second AR was stronger and lasted several days, bringing AR 3 conditions to Coastal Oregon
  • A mesoscale frontal wave developed along the second AR and resulted in an additional pulse of enhanced IVT and extended the overall duration of AR conditions
  • Several daily precipitation records were broken across the Seattle Metropolitan area where several both urban and river flooding was observed

MIMIC-TPW2 Total Precipitable Water

Valid 1200 UTC 17 December – 1700 UTC 22 December

Images from CIMSS/Univ. of Wisconsin

Click images to see loops of GFS IVT/IWV analyses

Valid 1200 UTC 17 December – 1200 UTC 22 December 2020







Summary provided by C. Hecht, C. Castellano, J. Kalansky, and F. M. Ralph; 23 December 2020