When it rains in California, it really damn pours. The weather phenomenon is known as an atmospheric river, a narrow but concentrated band of moisture that can transport as much water vapor as 15 Mississippi Rivers. Atmospheric rivers can make or break a drought, but there's still so much we don't know about how or why they form.

This Thursday though, when the next atmospheric river hits, scientist will be ready. CalWater 2015 is a unprecedented project to study the Pineapple Express, which is the name for atmospheric rivers that flow from Hawaii to California. The core of the project involves flying four research planes—essentially airborne laboratories—into the river itself. LiveScience's Becky Oskin explains what the planes will do:

Two of the other planes spend their summers as hurricane hunters, and one will release dropsondes, miniature parachutes that record weather data on their downward trip. Finally, NASA's high-flying ER-2 aircraft, the civilian equivalent of the U-2 spy plane, will skim over the clouds at 45,000 feet (13,700 meters) above the surface.


NOAA's biggest research ship, the Ronald H. Brown, has also been sitting off the coast of California waiting for the storm. The ship is loaded up with instruments, too, especially for studying aerosols and how they affect the formation of atmospheric rivers.

Armed with all this new data, scientists hope that they can make better predictions about when and where an atmospheric river will hit land. The rivers form all the time over the oceans, but only a handful make it to land every year. Fewer than usual have landed in California recently, contributing to the long drought. The Pineapple Express is now finally getting its scientific due—hopefully not too late. [LiveScience]

Top image: An atmospheric river as seen through water vapor. NOAA