An explosive grenade is nicknamed a pineapple. A recent storm that clobbered California is nicknamed the Pineapple Express and it has been just as explosive.
The innocent sounding name comes from the type of wind that lofts up from the tropics to the West Coast. In the day of sailing vessels, it helped speed the voyage from Hawaii to Seattle, thus the name Pineapple Express. Of course, sometimes when the warm moist air hit the cool continental land mass, it would precipitate out in heavy rains, but Seattle was used to rains.
December’s Express was more than a Northwest drizzle. The Pacific Ocean was in the middle of a strong La Niña. This meant the Tropical Pacific and waters off the American coastlines were cooler than normal. Meanwhile the Western Pacific was unusually warm. West Pacific tropical disturbances were stronger and they could travel further north and east. When they neared North America, they hit the winter-cooled land and created a deluge.
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Then the unexpected happened. The Arctic Oscillation has been strongly negative and has pushed a lot of US weather patterns further south than usual. (Just ask frozen Florida!) The Pineapple Express that normally sails happily to Seattle instead was steered south where it hosed down California.
This photo, taken by NASA satellite, shows the “pineapple express” storm that brought heavy rain to Southern California.
The results were stunning. For over a week California was hit by record-breaking storm after storm. Hillsides were hit with between 12 – 24 inches of rain, while one mountain sensor, Pascoes snotel, reported 17 feet of snow. From California, through Nevada, Utah, Colorado and Wyoming, regions reported up to 800% of their normal precipitation in that period. (See chart below. Credit: NOAA)
There were floods, landslides and avalanches, but not all results were bad. Reservoirs have been filled, Western snow packs are restored and California’s drought has nearly ended. Northern California is even reporting a resurgence in the number of returning salmon.
Most experts expect the Express to return to its normal Northwest route and California to return its normal dry La Niña weather. But it has been a pretty spectacular explosion for a wandering pineapple.
Have you ever “ridden” the Pineapple Express? Do we have any California fans? If you’d like to share your thoughts, I’d love to hear from you. (Just post comment below.)
James J. Garriss
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2010-11 was wet La Nina Heavy Rain in December 2010, then 2016-17 Weak La Nina had Pineapple Express storms, since the 1997-1998 El Nino in Southern California, and floods in Northern California since 1996-1997 Floods.
We had Weak La Nina wet year 2016-17 got floods in Northern California, then Southern California had wind and Rain on Feb 17, 2017, It has been since the El Nino of 1998 storms.
Here all this time I thought the Pineapple Express was a front that blew in from Hawaii. Kinda thought it was a might cool to have come from there.
WHY can't So Cal realize that if they had more resavoirs to catch this rain and run off that maybe they wouldn't need so much of N Ca's water from the ranchers and farmers that produce food for them? Every year they get fires and floods...duh
Most weather people only tell what the weather will be. It makes so much more sense when you (I!) know why. Thank you for this easy-to-understand explanation.
A really good explanation on The Pineapple Express and the havoc it caused, plus some of the benefits that accrued as a result. Very informative and well presented.
I live just south of San Jose. While we received a couple of inches of rain, we didn't experience anything like they did in southern California. I LOVE THE RAIN and hope the Pineapple Express stays around a bit longer. I'm not quite ready for spring.
Thank you for explaining this so well....thoroughly enjoyed reading it!
Living in Washington State, I've always heard terms like Pineapple Express and never knew exactly how they impact weather patterns. Thanks for the clear explanation!
Living in Seattle I am certainly used to the Northwest Drizzle! I loved the historical context in the article, thank you for the educational content. Well Done!
