Michael D. Dettinger, Fred Martin Ralph, Tapash Das, Paul J. Neiman and Daniel R. Cayan


Published date March 23, 2011

Atmospheric Rivers, Floods and the Water Resources of California

  • Shows that California experiences unusually large variations in annual precipitation and streamflow totals relative to the rest of the US, variations which mostly reflect the unusually small average number of wet days per year needed to accumulate most of its annual precipitation totals (ranging from 5 to 15 days in California)
  • States that this means whether just a few large storms arrive or fail to arrive in California can be the difference between a banner year and a drought
  • States that California receives some of the largest 3-day storm totals in the country, rivaling in this regard the hurricane belt of the southeastern US
  • States that California’s largest storms are generally fueled by landfalling atmospheric rivers (ARs)
  • Documents the fractions of precipitation and streamflow totals at stations across the US that are associated with ARs
  • Finds that, in California, ARs contribute 20–50% of the state’s precipitation and streamflow
  • Presents prospects for long-lead forecasts of these fractions
  • States that, from a meteorological perspective, California’s water resources and floods are shown to derive from the same storms to an extent that makes integrated flood and water resources management all the more important