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Waiting For The Rain

Here in Northern California, we are experiencing our typical October Indian Summer - warm days, clear skies, and for San Franciscans, a pennant race. Giant’s orange is seen on the streets everywhere, even the lights of City Hall are celebrating the home team.

It has been months since the last significant rainfall in the region as is typical in California. After lackluster rains last winter, it is easy to wonder if rain will come this year, and when will it start?

Earlier this year, the experts at the National Oceanic and Atmospheric Administration saw the first signs of an El Niño brewing in the equatorial Pacific ocean, which typically means a good rain year. But now they are not so sure.

As of Oct. 15, the official prediction is: Borderline ENSO-neutral/ weak El Niño conditions are expected to continue into Northern Hemisphere winter 2012-13, possibly strengthening during the next few months.

In other words, they can’t really say at this point.

If the ocean surface temperatures heat up we are in for a wet season. But El Niño periods are not reliable. Increased sea surface temperature in the eastern and central Pacific Ocean can last from 6 months to 4 years. And even that may be changing as our climate changes, sea ice shrinks at the North Pole, and our weather becomes even more unpredictable.

Here is the current view of the Pacific. A strong El Niño would show up as dark orange and red in the mid-Pacific, but that’s not really happening, yet.

Why is this important?

In the arid West, a good rainfall year can make a huge difference in whether we have enough water for our agriculture, for migrating bird species and native fish like the Delta smelt, or for cities that may be put on drought rations next summer. The downside of El Niño periods are cold water fish species in the ocean move north, out of traditional fishing grounds, and schooling forage fish often move into deeper waters.

During the winter of 11/12, while in the grip of La Niña (a cold ocean period), rainfall throughout the West was lacking but ocean conditions were beneficial to migrating species like whales, which love to chomp on abundant forage species who near the coasts when sea surface temperatures are cooler.

Historically, California goes multiple-year cycles of abundant rain and then drought. Water managers are trained to plan for the worst. The folks who operate the reservoirs in the state held back much of the water produced during the winter 2010/11. So while we may be entering a drought cycle, we are not officially desperate for water, yet. Another year of poor rainfall could change all that.

So for residents of Northern California, today we hold three thoughts simultaneously.

  1. Enjoy the weather.
  2. Pray for rain.
  3. Go Giants!
Tags:  climate change

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