PINEAPPLE EXPRESS PHENOMENON

• The Pineapple Express is a well-known atmospheric river which brings moisture from the tropical Pacific, near Hawaii, to the West Coast of the United States and Canada. It is a specific example of a common atmospheric phenomenon that resembles a conveyor belt for moisture.
• These rivers in the sky 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. And 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.
• When this moisture begins to interact with land, it can fall as rain or snow. Often, as is the case lately in California, the precipitation is abundant because these atmospheric rivers provide a continuous flow of moisture.
• Although atmospheric rivers come in different shapes and sizes, for one to be a “true Pineapple Express,” location matters. 
• 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.

3. The Science behind atmospheric rivers

4. What happens as a Result?

• Whether an atmospheric river is a Pineapple Express or not, the result is something like a conveyor belt for precipitation. 
• When the rivers are particularly strong or come back-to-back in what are called “atmospheric river families” the effects can be serious, like the extensive flooding that California is experiencing now.

For Prelims