Context: According to recent research, Atmospheric Rivers cause an average of $1.1 billion in flood damages yearly in the western U.S.

What are Atmospheric Rivers?

• 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.
• When that moisture reaches the coast and moves inland, it rises over the mountains, generating rain and snowfall. 

Do all Atmospheric Rivers Cause damage?

• Not all atmospheric rivers cause damage; most are weak systems that often provide beneficial rain or snow that is crucial to the water supply, particularly in the western United States.
• However, those atmospheric rivers that contain the largest amounts of water vapor and the strongest winds can create extreme rainfall and floods.

Where does the Atmospheric River occur?

• Atmospheric rivers occur globally, affecting the west coasts of the world’s major landmasses, including Portugal, Western Europe, Chile and South Africa.
• A well-known example is the “Pineapple Express,” a strong atmospheric river that is capable of bringing moisture from the tropics near Hawaii over to the U.S. West Coast.

Atmospheric Rivers in Dry and Wet Conditions

• In dry conditions, atmospheric rivers can replenish water supplies and quench dangerous wildfires. 
• In wet conditions, they can cause damaging floods and debris flows, wreaking havoc on local economies.
• A study on the damage caused due to Atmospheric Rivers
• According to a study, Atmospheric rivers cause an average of $1.1 billion in flood damages yearly in the western U.S.
• The study has also predicted that like hurricanes, atmospheric rivers are projected to grow longer, wider and wetter in a warming climate. This could lead to significantly larger economic impacts.