California Flood Threat From "Atmospheric River"

Meteorologists use the term "atmospheric river" to describe a long, narrow plume piping deep moisture from the tropics into the mid-latitudes. One type of atmospheric river (hereafter, AR) you may have heard of is the "Pineapple Express", a pronounced plume tapping moisture from the Hawaiian Islands to the U.S. West Coast.

Amazingly, according to NOAA's Earth System Research Laboratory (ESRL), a strong AR can transport as water vapor up to 15 times the average flow of liquid water at the mouth of the Mississippi River!