What exactly is a Pineapple Express?

Have you ever heard of a Pineapple Express? Also known as atmospheric rivers, they carry huge amounts of water vapor up in the atmosphere from the tropical region (hence the “pineapple” in the name) to the West Coast, where it then falls as massive amounts of rain. Atmospheric rivers are the source of much of California’s rainfall.

In a recent Watershed Wednesday presentation, Elissa Lynn, the climate change program section chief at California’s Department of Water Resources, talked about atmospheric rivers and the role they play in California’s water cycle. She also answered a series of questions about this weather phenomenon. Here’s an excerpt:

Is a Pineapple Express different than an Atmospheric River?

A Pineapple Express, the name California used to give these storms, are just one type of Atmospheric River. When scientists first began to study this type of storm, they believed that the band of moisture which forms over the tropics near Hawaii and makes its way to California was unique to the West Coast. Since then, scientists have found that these storms form in many places across the world and have started using “Atmospheric River” as a more general term for this type of water vapor transport.

To read the full interview, visit Q/A: Atmospheric Rivers and Their Impact on California’s Reservoirs. You can also see the full presentation below, courtesy of DWR’s YouTube channel.