El Niño 2015: Let’s Try It Again

El Niño 2015: Let’s Try It Again

I haven’t looked through the El Niño world this year. A year ago, with aplomb, we were working through the Super El Niño flurry. Here is my series from 2014.

May 2014:
Tracking El Niño
Underlying Models
August 2014:
Tracking El Niño: Summertime Update
October 2014:
El Niño, California Drought, and Predictions
December 2014:
California Drought, El Niño, Warm Earth (One more time)


Where are the 2015 Super El Niño blogs? They are around, but they don’t seem as present:

Can long anticipated ‘Super El Niño’ save California?
Growing buzz around potential “Super El Niño”
Onrush of Second Monster Kelvin Wave Raises Specter of 2015 Super El Niño
Update: Is a belated 'super' El Niño in the works for 2015?
A Strong El Niño Could Flourish by Fall: Five ways it could affect our weather

Reading through these blogs, the words are, for the most part, far more considered than in 2014. And, here, in 2015 we actually have an El Niño, though it is a bit of a strange one.

OK. El Niño and La Niña are names given to frequently occurring patterns of variation that are concentrated in the tropical Pacific Ocean, but that change the average temperature of Earth for about a year. When there is an El Niño the globe is warmer and when there is a La Niña the globe is cooler. Even though 2014 did not contain an official El Niño event, the eastern Pacific did warm, and 2014 went down as the warmest year of the modern record, since 1880. Here in 2015, with a warming in the eastern Pacific that meets the criteria of intensity and persistence of an El Niño, 2015 will undoubtedly be warmer still.

Starting with the March 2015 Diagnostic Discussion, the U.S. Climate Prediction Center (CPC) issued an El Niño advisory and stated that El Niño conditions were being observed. This statement was made as the warmer than average temperature in the Pacific Ocean were behaving in concert with the atmosphere. (Nice discussion of ocean-atmosphere relationships during El Niño by Bob Henson). Throughout the spring all of the forecast centers, listed below, forecast stronger El Niño conditions to take hold in summer and to continue through fall, and indeed, the rest of the year.

Northern Hemisphere springtime offers a special challenge for El Niño forecasters. Michelle L’Hereaux provides a nice discussion of the spring predictability barrier on the continuing-to-be-excellent NOAA ENSO Blog. Therefore, as the El Niño was observed to develop during the spring, we have seen the confidence in the forecasts increase. From the CPC May 14 discussion: “There is an approximately 90% chance that El Niño will continue through Northern Hemisphere summer 2015, and a greater than 80% chance it will last through 2015.” The May 26 summary from the Australian Bureau of Meteorology states, “The El Niño in the tropical Pacific continues to strengthen. International climate models surveyed by the Bureau indicate sea surface temperatures will remain well above El Niño thresholds at least into the southern hemisphere spring.” (Please note, that’s southern hemisphere spring, northern hemisphere fall.)

With regard to the predicted intensity, the International Research Institute for Science and Society states: “The consensus of ENSO prediction models indicate weak to moderate El Niño conditions during the May-July 2015 season in progress, likely strengthening during summer and lasting through 2015.”

Looking across the modeling centers current public statements, there is some information supporting the possibility of a very strong El Niño. However, there are a number of circumstances that suggest that an extreme or record El Niño is unlikely. These circumstances include the fact that we are just making it past that difficult springtime barrier that challenges the models; that the predictions for a very strong event lie on the edges of the distributions of the model predictions; and that the present El Niño conditions are unusual.

Bob Henson explains the unusual aspects of the present El Niño. Notably the connection between the atmosphere and ocean still don’t synchronize and correlate in the way that we have observed in both past events and successful forecasts. In fact, the current temperature patterns are more like those normally seen in classic El Niño Decembers.

It’s worth considering weather models and seasonal prediction models a little bit. Every day we have many weather events that we can use to learn to predict and improve weather models. We run through observational and forecast cycles, one after another, gaining experience. Weather forecasting is dominated by atmospheric observations and systems evolving in time ranges of hours to days. For El Niño we get an event every now and then, and there is only one at a time. Therefore, we’ve only had a small number of events since we have had the observations and modeling to provide confident forecasts. Not-so-well-observed ocean processes that evolve slowly, compared to weather systems, are involved. The fast evolving weather systems play with the slowly evolving ocean. Fundamentally, we don’t have as much experience with El Niño forecasting; we are far less likely to have experienced and observed the range of El Niño behavior.

All of challenges to modeling El Niño are compounded by the warming Earth and the changes in water vapor associated with warming oceans and atmosphere. This lack of stationarity, that is, the mean state of the Earth is changing, undermines our intuition. The past experiences are not as good a guide to assess forecast uncertainty as they used to be. This means that surprises outside of the forecast envelope are, in fact, more likely. That fact, however, does not mean that the models suggesting extreme events should be given higher value. To me, it means that high scrutiny should be given to the observations of the evolving El Niño, and that special attention should be given to the coherence of the processes that describe the dynamical features of the oceans and atmosphere.

Undoubtedly, globally 2015 will be warm, hot perhaps a better word. El Niño will be interesting. It is hard to justify the forecast of an extreme event; however, the situation on the ground is outside of our experience, and we should be on the lookout for surprises.

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Forecast and Analysis Centers

Climate Prediction Center Alert System and the Climate Prediction Center Diagnostic Discussion

International Research Institute Forecast Products and the Quick Look

Japanese Meteorological Agency El Niño Monitoring and Outlook and a nice graph of historical events

Australian Bureau of Meteorology Wrapup

Netherlands Meteorological Institute (KNMI) Forecasts

Information Portals

NOAA ENSO Blog

CLIVAR (Variability and predictability of the ocean-atmosphere system) Forecast Page

World Meteorological Updates

Pacific Marine Environmental Laboratory El Niño Theme Page Forecasts

Climate Prediction Center FAQ

NOAA’s El Niño Page and NOAA’s La Niña Page