WEATHER WEDNESDAY: The Pineapple Express

With apologies to our friends in the Boston area, some of whom have faced snowfall totals of nearly 5-feet in the last two weeks, we turn our attention to the west coast this week. We’re adding the term “Pineapple Express” to our glossary which so far this year includes Arctic Clipper and Blizzard.

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Atmospheric River from NOAA

A Pineapple Express is defined as a river of moisture fueling heavy rainfall and snowfall events in the Pacific Northwest and Northern California. The atmospheric moisture often passes through tropical regions of the Pacific Ocean including Hawaii, hence the name, “Pineapple Express.”

In the past week leading up to this publication date, notable heavy rains have fallen in Northern California repeating a scenario from December of last year. Rainfall totals of in excess of four inches to as much as eleven inches were common in the latest multi-day event. And while some local reservoirs are seeing a positive impact, the snowpack was not significantly affected so the storms are not considered a drought buster by any means.

Technically, a Pineapple Express is related to the Madden-Julian Oscillation, a major weather influencer that scientists are attempting to more thoroughly understand. The “river of moisture” may actually circle the globe in a 30 to 60 day cycle. Scientists are unleashing the power of supercomputers to enhance their knowledge of this and other atmospheric patterns.

Some of the threats and challenges associated with the Pineapple Express as it impacts the west coast of North America include:

  • Heavy rainfall
  • Flooding
  • Landslide
  • High Winds
  • Snowstorms
  • Severe Weather including isolated small tornadoes
  • Travel disruptions