The definition: An atmospheric river (AR) is a long plume of moisture that stretches from the tropics or subtropics into higher latitudes, often thousands of miles long. These thin ribbons of humid air can be identified and tracked in satellite imagery and computer model forecasts.

As the Bay Area prepares for another round of storms, a new Stanford study explains just how much damage atmospheric rivers can cause.

The biggest storm of the winter, packing a firehose of rain across much of California, will trigger flooding, mudslides and road closures that may put lives and property at risk during the latter part of this week.