Atmospheric Rivers Highlighted in the U.S. Fourth National Climate Assessment

November 6, 2017

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The Fourth National Climate Assessment, released last week, highlights atmospheric rivers as a key topic of its chapter on “Extreme Storms.” The other storm types addressed in this section are “tropical storms (hurricanes and typhoons),” “severe convective storms (thunderstorms)” and “winter storms.

The “Key findings” on atmospheric rivers are: “The frequency and severity of landfalling “atmospheric rivers” on the U.S. West Coast (narrow streams of moisture that account for 30%–40% of the typical snowpack and annual precipitation in the region and are associated with severe flooding events) will increase as a result of increasing evaporation and resulting higher atmospheric water vapor that occurs with increasing temperature. (Medium confidence).”

This major report further highlighted the atmospheric river topic by using a satellite image of an atmospheric river hitting the U.S. West Coast in February 2017 for the cover page of the entire report.

Contacts: Duane Waliser, F. Martin Ralph