What is the “Pineapple Express” Phenomenon?

January 13, 2023

Over the past two weeks, California and other parts of the West Coast have been hit with a series of what meteorologists call atmospheric rivers. Forecasters have said that the rain arriving in California on January 12 is being caused by a “true Pineapple Express” – a specific example of a common atmospheric phenomenon that resembles a conveyor belt for moisture. This article will examine the “Pineapple Express” phenomenon and its impact on California’s recent storms.

What is the “Pineapple Express” Phenomenon?

“Pineapple Express” is a specific example of a common atmospheric phenomenon known as atmospheric rivers. These rivers in the sky, also known as “rivers in the sky” according to the National Oceanic and Atmospheric Administration, are long, narrow regions in the atmosphere that transport most of the water vapor outside the tropics. They carry a lot of moisture – enough water vapor to equal or sometimes exceed the average flow of the Mississippi River at the point where it flows into the Gulf of Mexico.

For an atmospheric river to be classified as a “true Pineapple Express,” its location is key. The tail end, where the moisture is pulled into the atmosphere, must start near Hawaii. Then the river must stretch continuously through the atmosphere to the U.S. West Coast. This type of atmospheric river is known to bring heavy precipitation to the West Coast, as it is a continuous flow of moisture.

Is the “Pineapple Express” a common phenomenon?

Atmospheric rivers occur often on the West Coast but can happen in other locations, including the eastern United States, where they often channel moisture from the Caribbean. They are an essential part of the livelihood of coastal states, which rely heavily on precipitation for their water supply. Between 30% and 50% of the annual precipitation on the West Coast occurs from just a few atmospheric river events, according to the NOAA.

What are the effects of “Pineapple Express” storms?

When the atmospheric rivers are particularly strong – or come back-to-back in what are called “atmospheric river families” – the effects can be serious. This is the case in California, where the recent storms have led to extensive flooding. The “Pineapple Express” can be a double-edged sword, as it brings much-needed water to the state but also leads to destructive flooding if the storms are too strong.

The “Pineapple Express” is a common atmospheric phenomenon that brings much-needed precipitation to the West Coast. However, when the storms are particularly strong, as is the case in California, the effects can be severe. Understanding the “Pineapple Express” and its impact on the state’s weather patterns is essential in being able to predict and prepare for future storms.

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