CW3E Outlook: 17-22 Nov Cutoff Low

November 19, 2019

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Cutoff low and subsequent shortwave trough will bring widespread rainfall to the U.S. Southwest

  • A cutoff low pressure system west of the Baja Peninsula will transport large amounts of water vapor into the Southwest in the coming week
  • Meanwhile, a separate storm will drop down the coast from the north, with a decaying atmospheric river, and form a strong closed low that will entrain the weakening cutoff low and its tropical water vapor
  • This second system will then move into the Southwest, producing widespread 1-3 inches of rain and snow (liquid equivalent) over parts of AZ, UT, and southern NV, with over 5 inches of liquid equivalent in parts of Arizona over roughly 4 days
  • Higher elevations may see 2-3 feet of snow accumulation
  • Lower precipitation amounts (less than 1-2 inches) are expected across Southern California and the Southern Sierra Nevada
  • In Arizona, this 4-day period is predicted to produce at least 10-25% (and even as much as 40-50% in some locations) of November-April average total precipitation








Summary provided by F. M. Ralph and N. Oakley; 19 November 2019