Atmostpheric Rivers (ARs) are long, narrow shaped streams of water - and lots of it. Nicknamed "Pinapple Express" they form when winds over the Pacific draw moisture from the warm, moist air over the tropics and channel it toward the West Coast. When this ribbon of moisture meets mountains, it is forced upward, cooling it and turning its water into immense quantities of rain and snow.
Learn more on the National Oceanic and Atmospheric Adminstration (NOAA) website:
- CA DWR - Atmospheric rivers and Their Impact on California's Reservoirs, 10/28/20
- Scientific American - Better Atmospheric River Forecasts Are Giving Emergency Planners More Time to Prepare for Flooding, 9/1/22
- San Francisco Chronicle - How tracking atmospheric rivers could transform California's reservoir levels during drought, 12/27/22
- National Geographic - ‘Rivers in the sky’ are why California keeps flooding, 3/10/23