Weather Watch

El Niño or La Niña this winter? More like ‘El Nothing,’ forecasters are now saying

The Climate Prediction Center has backed off its forecast for a weak or moderate El Niño during winter 2017-18, and the National Oceanic Atmospheric Administration is now predicting neutral conditions.
The Climate Prediction Center has backed off its forecast for a weak or moderate El Niño during winter 2017-18, and the National Oceanic Atmospheric Administration is now predicting neutral conditions. ldickinson@thetribunenews.com

The Climate Prediction Center has backed off its forecast for a weak or moderate El Niño this winter, and the National Oceanic Atmospheric Administration is now predicting neutral conditions — the infamous El Nothing.

At this time of the year, it’s understandable as these predictions often change. Here’s why:

We’re in the so-called “Spring Predictability Barrier.” In spring, the El Niño Southern Oscillation (ENSO) is often in transition from one phase to another. For example, an El Niño condition could be decaying and passing through neutral condition to a La Niña phase, or vice versa.

Of course, as you get closer to winter, the models become more accurate because there’s less time for inaccurate oceanographic and atmospheric data to be amplified at model initialization. In this time of the year, you can either shake your fist at the sky in frustration, or as astrophysicist Dr. Ray Weymann of Atascadero would say: “Many climate scientists think the most reliable strategy is ‘WAS’ (wait and see).”

As the temperatures and currents of the Pacific change, so does our weather. Changing conditions in the Pacific Ocean can trigger El Niño and its sister, La Niña, which can actively influence our weather, either wet or dry. Neutral conditions typically don’t produce any reliable seasonal rainfall predictions along the Central Coast.

Since 1950, NOAA has used sea surface temperatures (SST) in a central equatorial region of the Pacific Ocean called Niño 3.4 as the standard for classifying El Niño (warmer-than-normal SST) and La Niña (cooler-than-normal SST) events. The fortunetelling SST cycles in Niño 3.4 are categorized by the amount they deviate from the average SST — in other words, an anomaly.

A weak El Niño is classified as an SST anomaly between 0.5 and 0.9 degrees Celsius. A moderate El Niño is an anomaly of 1.0 to 1.4 degrees Celsius. And a strong El Niño ranges from 1.5 to 1.9 degrees Celsius. A very strong El Niño anomaly is anything above 2.0 degrees Celsius (or 3.6 degrees Fahrenheit). Neutral conditions — El Nothing or El Nada — range between plus 0.5 and minus 0.5 degrees Celsius anomaly levels — or the sector between El Niño and La Niña.

Another powerful oceanographic cycle that can orchestrate changes in our weather is a longer-lasting cycle called the Pacific Decadal Oscillation or PDO. While the ENSO phase typically lasts from eight to 13 months, the PDO alternates between a warm phase (positive) and a cool (negative) phase that can last a few years to decades. Unlike El Niño, which focuses on SST in the central equatorial region of the Pacific Ocean, the PDO is classified by seawater temperatures throughout the northern Pacific Ocean.

According to climatologist Bill Patzert of NASA’s Jet Propulsion Laboratory in Pasadena, the PDO shifted to the positive in 2014 and has remained that way for past 38 months. Historically, the positive phase of the PDO typically enhances the effects of El Niño and La Niña events. Historically along the Central Coast, El Nothing combined with a positive PDO has produced near average amounts of rainfall.

As far as air temperatures, the Climate Prediction Center is calling for above average temperatures for nearly the entire North American continent, including the Central Coast, through July if not longer.

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PG&E, Sentinels of Freedom and Sonoma Raceway will join forces to play host to the third Military Career Day at the raceway’s NASCAR Cup Series weekend on June 23. The event will include workshops, panel presentations and a job fair featuring more than 40 Bay Area companies.

“Veterans, especially those with a service-related disability, may need help transitioning into long-term civilian careers. We’re proud to sponsor the third Military Career Day at Sonoma Raceway as part of our continuing support of veterans,” said Mary King, PG&E’s vice president of human resources, a member of the board of directors for Sentinels of Freedom and a former Army Captain.

For more information, visit http://www.pgecurrents.com/.

John Lindsey’s column is special to The Tribune. He is PG&E’s Diablo Canyon marine meteorologist and a media relations representative. Email him at pgeweather@pge.com or follow him on Twitter @PGE_John.

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