Severe Storms/Atmospheric Rivers

This page is to be used for the Severe Storms topic of the Meteorology event.

Atmospheric Rivers
Atmospheric rivers are narrow bands of enhanced water vapor transport. They are often found in the warm sectors of mid-latitude cyclones that form over water. The warm sector can also entrain moisture from oceanic regions.

Characteristics of Atmospheric Rivers
Atmospheric rivers (ARs) are narrow, usually only about 100 kilometers wide, move quickly, about 85 kilometers per hour at the core, and are centered about one kilometer above the surface. ARs are responsible for almost all (>90%) of the global north-south transport of water vapor. Some ARs carry up to 50,000,000 liters of water per second.

Impact
Atmospheric rivers are largely responsible for incidences of extreme precipitation in the west coast regions of the middle latitudes (e.g., the West Coast of North America, western Europe, and western North Africa). These incidences of extreme precipitation result in severe flooding.

Precipitation from ARs likely caused the Great Flood of 1862. The USGS has developed a theoretical scenario called ARkStorm in which an AR causes extreme flooding in much of California.