It’s been easy to sit comfortably here on the West Coast and feel secure because we don’t have hurricanes like Sandy. That’s because the water temperature in the Pacific Ocean isn’t warm enough to sustain a hurricane to landfall.
But geologist Jeffrey Mount reminds us that the West Coast has its own form of nasty tropical storms, called the “Pineapple Express,” that could do just as much damage as Hurricane Sandy did this week back East.
A Pineapple Express brings a strong and persistent flow of atmospheric moisture from Hawaii resulting in torrential rainfall as it hits the shore. These so-called “atmospheric rivers” were responsible for the biggest flooding event in California history in 1862, when rain fell in Biblical proportion for 30 days and 30 nights. The Central Valley became a giant lake 300 miles long and 20 miles wide.
And there have been more recent incidents, namely two major floods in Northern California in 1952, and the Christmas Flood of 1964.
Climate change may well increase the frequency and severity of the Pineapple Express, just as it’s caused East Coast flooding from extreme storms like Hurricane Sandy to become practically commonplace.
Climate modeling by U.S. Geological Survey hydrologist Mike Dettinger has shown that extreme weather events on the West Coast will increase by 50 percent and could double in size. We could even start getting a big increase in “extreme-season” years, in which we see 10 to 20 bad winter storms.
Mount, the founding director of the UC Davis Center for Watershed Sciences, notes that flooding from a major storm in the Bay Area would put more than 140,000 people at risk and could lay waste to $30 billion of public assets that include the Port of Oakland, two major airports and 800 miles of roadways.
All that’s to say that Hurricane Sandy should be causing us on the West Coast to look around at how much we stand to lose with our Pineapple Express.
Alison Hawkes is the online editor of Bay Nature.