Pineapple Express facts for kids
The Pineapple Express is a special weather event. It's like a long, narrow "river" of warm, wet air that flows across the Pacific Ocean. This "river" starts near the Hawaiian Islands (where pineapples grow!) and stretches all the way to the west coast of North America. When it hits land, it brings a lot of rain and sometimes snow. It's a natural weather pattern that happens again and again.
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What Causes a Pineapple Express?
A Pineapple Express happens because of a strong, southern branch of the jet stream. The jet stream is like a fast-moving air current high in the atmosphere. This event also involves a slow-moving weather front on the ground. Small areas of low pressure often travel along this front, bringing more rain.
Sometimes, a weather pattern called the Madden–Julian oscillation helps create these events. This pattern moves moisture from near the equator into the Pineapple Express. They can also happen more often during an El Niño event.
What Happens When it Hits Land?
When this warm, wet air reaches the mountains along the west coast of North America, it rises. As it rises, it cools, and all the moisture turns into heavy rain. This is why areas like California, Oregon, and Washington get huge amounts of rain during a Pineapple Express.
These systems often bring heavy snowfall to the mountains. But because the air is warm, this snow can melt quickly, sometimes causing floods. After the air loses its moisture over the mountains, it can become a warm, dry wind called a Chinook wind in the inland areas.
Major Pineapple Express Events
Many Pineapple Express events happen after or during cold weather. This can lead to big floods when warm rain falls on frozen, snow-covered ground. Some famous examples include the Christmas flood of 1964 and the Willamette Valley flood of 1996.
The Great Flood of 1862
In early 1862, extreme storms from the Pineapple Express hit the west coast for 45 days. Some places got an estimated 8.5 feet (2.6 meters) of rain! This caused the worst flooding ever recorded in California, Oregon, and Nevada. The Sacramento and San Joaquin valleys were completely flooded. There were also many mudslides.
Northern California, 1952
The San Francisco Bay Area sometimes gets hit by a Pineapple Express. Before the 1980s, people often called these "Hawaiian Storms." In January 1952, a series of these storms caused widespread flooding around the Bay Area. These storms also brought a huge, wet snowstorm to the Sierra Nevada Mountains. A famous train, the City of San Francisco, got stuck in the snow on January 13.
Southern California, 2005
A Pineapple Express storm hit Southern California from January 7–11, 2005. This was the biggest storm to hit the area since the 1997–98 El Niño event. It caused mudslides and floods. One desert spot got about 9 inches (229 mm) of rain. Some mountain areas got even more, with one place receiving over 31 inches (790 mm) of rain in five days!
Pacific Northwest, 2006
In November 2006, the Puget Sound region in Washington and British Columbia got several inches of rain each day. A series of Pineapple Express storms caused massive flooding in rivers and mudslides. These mudslides closed mountain passes. Officials said it was "the worst storm in a decade."
California, December 2010
In December 2010, a Pineapple Express system hit California from December 15–22. It brought as much as 2 feet (610 mm) of rain to the San Gabriel Mountains. The Sierra Nevada mountains got over 13 feet (4 meters) of snow! Many coastal and hillside areas had mudslides and major flooding.
California, December 2014
A powerful winter storm, made stronger by a Pineapple Express, hit California in December 2014. It brought snow, strong winds, and floods. For the first time in years, a blizzard warning was issued for the Northern Sierra Nevada. The storm caused power outages for more than 50,000 people. A rare tornado even touched down in Los Angeles on December 12.
West Coast, 2017
Historically strong storms linked to the Pineapple Express brought floods and mudslides to California in 2017. The San Francisco Bay Area was especially affected. Homes were destroyed, and many roads had to close. The storm also brought huge amounts of snow to the Sierra Nevada and San Gabriel Mountains. One place in the Sierra recorded up to 800 inches (20 meters) of snow! It also caused significant flooding in the Los Angeles area.
California, January 2021
A powerful winter storm, channeling a Pineapple Express, hit California from January 26–29, 2021. One person was hurt in a mudslide, and many buildings were damaged. The storm killed at least two people. A large part of California State Route 1 along the Big Sur coast collapsed into the ocean. This happened after massive amounts of rain caused a debris flow onto the highway. In Southern California, the storm caused widespread flooding and debris flows. Thousands of people had to evacuate their homes. Across California, about 575,000 people lost power at one point. The mountains got huge amounts of snow. Mammoth Mountain Ski Area received 94 inches (239 cm) of snow in just 72 hours! Very strong winds were also recorded, with gusts over 100 mph (161 km/h).
Pacific Northwest, 2021
Heavy rains from a Pineapple Express hit the Puget Sound region in Washington and British Columbia from November 14–15, 2021. Bellingham, Washington, received 2.78 inches (71 mm) of rain on November 15 alone. The floods and mudslides that followed closed all major Canadian roads leading to Vancouver, British Columbia.
California, 2022–2023
Heavy rains from a Pineapple Express caused widespread flooding in the Bay Area during 2022 and 2023.
California, February 2024
A Pineapple Express storm hit California from February 1 to 2, 2024. Another one hit from February 3 to 5. The National Weather Service called it "potentially life-threatening." News sources estimated that Los Angeles received six months' worth of rain in just 48 hours! The Sierra Nevada mountains got 1 to 3 feet (30 to 91 cm) of snow, with over 4 feet (122 cm) expected in higher areas. Some parts of the San Bernardino Mountains' foothills received 10 to 12 inches (254 to 305 mm) of rain.
See also
- ARkStorm
- Pacific Organized Track System
- Siberian Express
- Typhoon Cimaron (2006)
