Atmospheric river storms can drive costly flooding — and climate change is making them stronger
[...]
Atmospheric rivers are long, narrow bands of moisture in the atmosphere that extend from the tropics to higher latitudes. These rivers in the sky can transport 15 times the volume of the Mississippi River.
[...]
In the past 20 years, as observation networks have improved, scientists have learned more about these important weather phenomena. Atmospheric rivers occur globally, affecting the west coasts of the world’s major land masses, including Portugal, Western Europe, Chile and South Africa. So-called “Pineapple Express” storms that carry moisture from Hawaii to the United States West Coast are just one of their many flavors.
[...]
We found that atmospheric rivers caused an average of $1.1 billion in flood damages yearly in the western U.S. More than 80% of all flooding damages in the West in the years we studied were associated with atmospheric rivers. In some areas, such as coastal northern California, these systems caused over 99% of damages.
[...]
Like hurricanes, atmospheric rivers are projected to grow longer, wider and wetter in a warming climate. Our finding that damages increase exponentially with intensity suggests that even modest increases in atmospheric river intensity could lead to significantly larger economic impacts.
[...]