A powerful storm continues to batter California, bringing downpours and causing extensive flooding across much of the state.California has been plagued by recurring storms for several weeks. In recent days, torrential rains have arrived on saturated soils, causing massive flooding. Seventeen people died, swept away by the waters. After two decades of drought and fires, California is under water. In question: a meteorological phenomenon called pineapple express or "pineapple express". It is an atmospheric river, a band of rain that circulates through the atmosphere, originating on the Hawaiian side, which explains its name.A series of depressions over several weeks This river is several hundred miles wide and stretches thousands of miles long, extending to the west coast of the United States. Due to its immense size, it brings a series of depressions heavily laden with humidity from the tropics, causing torrential rains over several days or even weeks.There are episodes of pineapple express almost every year between southern Alaska and northern Mexico. Devastating events like the one currently affecting California sometimes occur when a large mass of cold arctic air meets tropical air.The rains also fall at higher altitudes in the mountains and can cause part of the snowpack to melt, which then adds to runoff and aggravates flooding. Devastating storms.Major roads cut, landslides, falling trees... The damage in California is very significant. In Montecito, luxurious villas are now drowned in water and mud and more than 100,000 homes are without electricity. The city of San Francisco had never experienced so much rain since the start of weather records.This heavy rainfall is expected to last until at least Sunday in the Golden State and a new wave of rain is expected in the next few hours on Wednesday.