West coast, 1862 Įarly in 1862, extreme storms riding the Pineapple Express battered the west coast for 45 days. Examples of this are the Christmas flood of 1964, Willamette Valley flood of 1996, New Year's Day Flood of 1997, January 2006 Flood in Northern California and Nevada, Great Coastal Gale of 2007, January 2008 Flood in Nevada, January 2009 Flood in Washington, the January 2012 Flood in Oregon, the 2019 Valentine's Day Flood in Southern California, and the February 2020 floods in Oregon and Washington. Many Pineapple Express events follow or occur simultaneously with major arctic troughs in the northwestern United States, often leading to major snow-melt flooding with warm, tropical rains falling on frozen, snow laden ground. ( September 2018) ( Learn how and when to remove this template message) Please help improve this article if you can. The specific problem is: This section should not present an exhaustive list.

This article may require cleanup to meet Wikipedia's quality standards. After being drained of their moisture, the tropical air masses reach the inland prairies as a Chinook wind or simply 'a Chinook', a term which is also synonymous in the Pacific Northwest with the Pineapple Express. Pineapple Express systems typically generate heavy snowfall in the mountains and Interior Plateau, which often melts rapidly because of the warming effect of the system. The combination of moisture-laden air, atmospheric dynamics, and orographic enhancement resulting from the passage of this air over the mountain ranges of the western coast of North America causes some of the most torrential rains to occur in the region.

They are also present during an El Niño episode. The conditions are often created by the Madden–Julian oscillation, an equatorial rainfall pattern which feeds its moisture into this pattern. Each of these low-pressure systems brings enhanced rainfall. How the Madden–Julian oscillation can induce a Pineapple ExpressĪ Pineapple Express is driven by a strong, southern branch of the polar jet stream and is marked by the presence of a surface frontal boundary which is typically either slow or stationary, with waves of low pressure traveling along its length.

Pineapple express for free