Atmospheric rivers are relatively long, narrow areas of the atmosphere that convey the majority of the water vapor outside of the tropics. These vapor columns travel with the weather, and when they strike landfall, they frequently discharge water vapor in the form of rain or snow.
NOAA research (e.g., NOAA Hydrometeorological Testbed and CalWater) uses satellite, radar, aircraft and other observations, as well as major numerical weather model improvements, to better understand atmospheric rivers and their importance to both weather and climate.
These atmospheric rivers can cause transport disruption, mudslides, and catastrophic damage to life and property. The “Pineapple Express,” a powerful atmospheric river capable of transporting precipitation from the tropics near Hawaii to the United States’ West Coast, is a well-known example.
A series of atmospheric rivers fueled the strong winter storms that battered the U.S. West Coast from western Washington to southern California from Dec. 10–22, 2010, producing 11 to 25 inches of rain in certain areas. These rivers also contributed to the snowpack in the Sierras, which received 75% of its annual snow by Dec. 22, the first full day of winter.
Not all atmospheric rivers inflict harm; most are weak systems that frequently bring helpful rain or snow that is critical to the water supply. Atmospheric rivers are a key feature in the global water cycle and are closely tied to both water supply and flood risks.
Reference- NOAA, National Geographic, Global Weather News, CNN, The Guardian