Rolling the dice on El Nino: Too soon to predict?

Given that this is the worst drought on record in California, it's natural for people to hope for El Niño and all the rain that a good strong El Niño can bring. As the San Francisco Chronicle reported:

…even as hope dims for a March miracle storm, climatologists say weather conditions could change this year if an El Niño takes shape. The U.S. Climate Prediction Center issued an El Niño watch this month, citing a 52 percent chance of Pacific Ocean waters warming and creating – possibly – a wetter-than-average winter.

The possibilities were discussed more thoroughly by Bob Henson of the National Center for Atmospheric Research earlier this month. Henson hinted at an underlying excitement:

Most of the El Niño events over the last 15 years have been on the weaker side. However, some conditions in the western tropical Pacific are now strikingly similar to those that preceded the two strongest El Niño events of the last century: 1982–83 and 1997–98.

If El Niño doesn’t take shape in the next several months, we may not see it this year at all. “Once you get toward summer, the odds of getting a major El Niño certainly start to go down,” says NCAR scientist Kevin Trenberth.

Should a truly significant El Niño event develop by June or July, it would give us months of advance notice about which parts of the United States are likely to be cooler, milder, wetter, or drier than average come next winter. You still wouldn’t have a specific forecast for New Year’s Day or Groundhog Day in your hometown, but even a slight shift in seasonal odds—as long as it’s a confident shift—could mean millions of dollars for utilities, agricultural firms, insurance companies, and others in a position to hedge big bets.

Yet note the hedge: "most of the El Niño events of the last fifteen years have been on the weaker side." Ask Bill Patzert of JPL/NASA, one of the best forecasters of the phenomenon, why that might be and he will point to a larger ocean phenomena — the Pacific Decadal Oscillation — and argue that there's a reason most of these events have been weak. They've been swamped by the PDO, which turned negative fifteen years ago. It's still strongly negative, as this chart from the U of Washington shows:

Pdoindex_big
 

It's noteworthy that the most prominent critic of NOAA's predictions has been right in the past, about El Niño, and is saying pretty much what he was saying seven years ago, when an El Niño event was predicted. From a great story by Hector Becerra in the Los Angeles Times in March 2007:

When it comes to El Niño, NOAA tends to emphasize data
from a network of buoys running across the equatorial Pacific from Asia to
the Americas. They make measurements on the upper 500 meters in the
ocean, where the major deviations in temperature take place. The weather
consequences can be dramatic depending on the size of the temperature
increase, the area of ocean involved and the duration of the phenomenon.

For NOAA, an increase of about 1 degree Fahrenheit over three months in
a defined area of the Pacific meets the threshold for El Niño.

Patzert, on the other hand, is an expert in analyzing satellite data.
The satellites measure the elevation of the sea surface as a result of the
expansion of water as temperatures increase in the upper 500 meters. The
satellites are not as hyperfocused on El Niño and look beyond to other
climate patterns.

One of those patterns is the Pacific Decadal Oscillation, a slow-moving
variation of temperatures between the western and eastern sections of
the Pacific. In 1998, the western Pacific was becoming warmer than the
eastern Pacific, leading Patzert to conclude that in the long term, an "El
Niño-repellent" pattern was forming that would favor drought in Southern
California for many years.

Patzert still sees an  El Niño-repellant pattern in place, and has scoffed at "the great WET hope" before, and may scoff again. Even the chart the forecasters put up as evidence of  El Niño looks a little thin:

Enso_outlook_CPC_march6

How many chips do you want to put on a 52% probability? 

Related articles

Is A Super El Niño Coming That Will Shatter Extreme Weather And Global Temperature Records?
Talk of a 'super' El Niño out in the Pacific
Drought expert to Ojai: You have too many damned trees
El Nino and Summer

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