Rivers in the sky What is an atmospheric river?

  

The first of two significant atmospheric river storms barreled into the Bay Area on Wednesday, bringing heavy rain, flooding, and causing trees to fall. Rain is expected to continue over the next few days. Yea, Yea I know, I'm a weather nerd. What is an atmospheric river? Well do you want the nerdy weather lingo or layman's terms? 

Now I'm not a meteorologist or a scientist. the only meteorology study I have done has been a few college classes along with self-study. The term Atmospheric River refers to a storm that is able to tap into the abundant moisture of the tropics. These atmospheric regions transport most of the water vapor outside of the tropics and can vary greatly in size and strength, a typical atmospheric river can carry an amount of water vapor roughly equivalent to the average flow of water at the mouth of the Mississippi River.

When atmospheric rivers make landfall, they can release the water vapor they carry in the form of rain or snow. These weather phenomena come in many shapes and sizes. Those with larger amounts of water vapor and stronger winds can create extreme rainfall and floods, especially when they stall over watersheds vulnerable to flooding.

When that happens, travel can be disrupted, mudslides can be triggered and potentially catastrophic damage to life and property can be unleashed. A “Pineapple Express” is a strong atmospheric river that brings moisture from the tropics near Hawaii to the US West Coast. So, it supercharges our rainfall and snow totals.

When you look at satellite images you can usually clearly see this plume of water vapor and it will sometimes extend all the way back to Hawaii, thus the term ‘Pineapple Express’ is also used to describe this weather event. So, Yea it is basically a river in the sky, But with a whole in the ground.