Here's an explanation of how they form, their size and potential impacts. WHAT IS AN ATMOSPHERIC RIVER? The weather system occurs all over the world. It starts when a large amount of water vapor ...

After unleashing dozens of destructive tornadoes, a slow-moving storm system dumped heavy rain across the U.S. Midwest and ...

"That moisture plume, known as an atmospheric river, will be tropical in nature and originate from the Caribbean," AccuWeather Senior Storm Warning Meteorologist William Clark said in the report.

When a bomb cyclone meets an atmospheric river, the result is like an out-of-control fire hose A powerful storm hitting the West Coast combines these weather phenomena for a wet week in many areas.

Map of Sierra Nevada in California showing how an atmospheric river develops. Most atmospheric rivers are weak and do not cause damage. In fact, they can provide much-needed rain or snow.