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El Niño or Bust

Filed under: — mike @ 8 May 2014

Guest commentary from Michelle L’Heureux, NOAA Climate Prediction Center

Much media attention has been directed at the possibility of an El Niño brewing this year. Many outlets have drawn comparison with the 1997-98 super El Niño. So, what are the odds that El Niño will occur? And if it does, how strong will it be?

To track El Niño, meteorologists at the NOAA/NWS Climate Prediction Center (CPC) release weekly and monthly updates on the status of the El Niño-Southern Oscillation (ENSO). The International Research Institute (IRI) for Climate and Society partner with us on the monthly ENSO release and are also collaborators on a brand new “ENSO blog” which is part of (co-sponsored by the NOAA Climate Programs Office).

Blogging ENSO is a first for operational ENSO forecasters, and we hope that it gives us another way to both inform and interact with our users on ENSO predictions and impacts. In addition, we will collaborate with other scientists to profile interesting ENSO research and delve into the societal dimensions of ENSO.

As far back as November 2013, the CPC and the IRI have predicted an elevated chance of El Niño (relative to historical chance or climatology) based on a combination of model predictions and general trends over the tropical Pacific Ocean. Once the chance of El Niño reached 50% in March 2014, an El Niño Watch was issued to alert the public that conditions are more favorable for the development of El Niño.
Current forecasts for the Nino-3.4 SST index (as of 5 May 2014) from the NCEP Climate Forecast System version 2 model.
Current forecasts for the Nino-3.4 SST index (as of 5 May 2014) from the NCEP Climate Forecast System version 2 model

More recently, on May 8th, the CPC/IRI ENSO team increased the chance that El Niño will develop, with a peak probability of ~80% during the late fall/early winter of this year. El Nino onset is currently favored sometime in the early summer (May-June-July). At this point, the team remains non-committal on the possible strength of El Niño preferring to watch the system for at least another month or more before trying to infer the intensity. But, could we get a super strong event? The range of possibilities implied by some models allude to such an outcome, but at this point the uncertainty is just too high. While subsurface heat content levels are well above average (March was the highest for that month since 1979 and April was the second highest), ENSO prediction relies on many other variables and factors. We also remain in the spring prediction barrier, which is a more uncertain time to be making ENSO predictions.

Could El Niño predictions fizzle? Yes, there is roughly a 2 in 10 chance at this point that this could happen. It happened in 2012 when an El Nino Watch was issued, chances became as high as 75% and El Niño never formed. Such is the nature of seasonal climate forecasting when there is enough forecast uncertainty that “busts” can and do occur. In fact, more strictly, if the forecast probabilities are “reliable,” an event with an 80% chance of occurring should only occur 80% of the time over a long historical record. Therefore, 20% of the time the event must NOT occur (click here for a description of verification techniques).

While folks might prefer total certainty in our forecasts, we live in an uncertain world. El Niño is most likely to occur this year, so please stay attentive to the various updates linked above and please visit our brand new ENSO blog.

68 Responses to “El Niño or Bust”

  1. 51
    delay says:

    No problem. But I think the continuity is a bit sus.

  2. 52
    Mike S says:

    I must be missing something really obvious. According to slide 21 of the NOAA Weekly ENSO Update, the Oceanic Nino Index has been negative the last few months, which is indicative of La Niña conditions rather than the El Niño. Is this right? What am I misreading?



  3. 53
    Hank Roberts says:

    Mike S, see Slide 26 of that document you mentioned.
    Slide 21 is the past up through April.

  4. 54
    Robert says:

    Yes negative is due to Kelvin wave. This is expected.

  5. 55
    Mike S says:

    Thanks. It’s great to have such knowledgable responses.

  6. 56

    ENSO is essentially a standing wave pattern that doesn’t show a perfect periodicity and the classic sinusoidal waveform. Instead what it likely comprises is an erratic quasi-periodic pattern — caused by the interaction of a nearly periodic forcing such as from QBO (quasi-biennial oscillations in wind) with a Kelvin wave modulation.

    This sets up a nonlinear sloshing behavior that most scientists admit is very hard to predict. But that doesn’t mean we can’t try. This is my latest attempt at solving a modulated differential wave equation.

    The key is to reduce the dimension of the parameter space as much as possible to avoid accusations of overfitting. This is nowhere near as easy as doing a FFT and picking out the Fourier components. Solving the differential equation is essentially integrating the nonlinear equation from the initial conditions to the current time and matching the intermediate waveform along the intermediate points.

    Surprisingly, the initial conditions are not quite as important as one might naively imagine. As it turns out, the overriding boundary conditions are set by the forcing of the QBO.

    Get this right and we can go a long way in being able to predict ENSO.

  7. 57
    Mike S says:

    El Nino seen as probably weak by two forecasters as event looms claims an 80% chance of a weak El Nino, but I have no idea of the credentials of the “forecasters”. Is there a general expectation of a weak El Nino among experts?

  8. 58
    wili says:

    Mike S @ #57: Thanks for that link. My understanding is that, until May was over, making firm predictions was somewhat dicey. I also get the impression from chatter at various sites and the NOAA forecasts that it is now looking like it may not be a super El Nino, but it is getting to be quite a high probability that some kind of El Nino will be fully here by mid to late summer.

    A recent piece I, at least found to be helpful in discussing what goes in to predictions is here:

  9. 59
    JCH says:

    ENSO ONI for MAM is -0.2, down from -0.5.

  10. 60
    GlenFergus says:

    The Australian Bureau of Meteorology’s dynamic model no longer predicts an El Niño in its June update.

  11. 61
    Hank Roberts says:

    Note, when reading the original post at the top — as it says at the bottom of the OP,

    please stay attentive to the various updates linked above and please visit our brand new ENSO blog.

    And note that what you see displayed above is the most recent image to date from that source (says June 11, as of right now).

  12. 62
    Hank Roberts says:

    PS for Glen Fergus — I followed your link posted June 7th but it doesn’t go to a page mentioning the Australian Bureau of Meteorology’s dynamic model; do you have a better pointer?

    That link as of today goes to their Outlooks page which says “Tropical Pacific Ocean remains on track for El Niño in 2014 … Issued on Tuesday 3 June 2014” and “Next update expected on 17 June 2014”

    but I didn’t find their dynamic model info.

  13. 63
    wili says:

    Update from the BOM still giving El Nino a 70% chance.

    And yesterday’s NOAA forecast update says:

    “Chance of El Niño is 70% during the Northern Hemisphere summer and
    reaches 80% during the fall and winter.”

  14. 64
    GlenFergus says:

    Looks like a BOM site glitch Hank; not obeying the #tabs in

    Just click tab “Outlooks”; graph there is of POAMA (BOM’s dynamic model) June 1 output for Nino3.4.

    Or direct link to graph here: Or actual model page is here:

    (Obviously they don’t believe their own model though, because as Wili says, the overview text says 70% chance of El Niño:

  15. 65
    JCH says:

    Click on outlook. Lower left of the forecast graphic is a button. Click on see also: climate model summary. There are buttons for July, September, November. Click on September and you’ll see how many models are forecasting El Nino by then, 4 of 8. Click on November, 5 of 8. I assume the one called BoM is the one GlenFergus is talking about, and it stays neutral throughout.

    I don’t know if this has any relevancy, but to this point in 1997 ONI was -0.5, -0.4, -0.1, and +0.2 versus current: -0.6, -0.6, -0.5, and -0.2.

  16. 66
  17. 67
    DP says:

    Re #66 Usually an El Nino is good news for Texas and the African Sahel and bad news for Australia and India.

  18. 68
    Hank Roberts says:

    With the caveat that New Scientist is an entertainment magazine, not a science magazine, herewith their latest on El Nino:

    … Meteorologists contacted by New Scientist all expect an El Niño at the end of this year. And it looks like a big one, says Wenju Cai of CSIRO, Australia’s national research agency, in Melbourne. The more heat in the Pacific, the bigger the El Niño, and right now, 150 metres below the surface, a ball of warm water is crossing that ocean. “It’s huge,” says Cai.

    Yet official forecasts remain cautious. As recently as 5 May, the US National Oceanic and Atmospheric Administration only said the odds of an El Niño would exceed 50 per cent this year.

    Most El Niño researchers say forecasters are being too conservative. “One thing I hear over and over again is ‘we do not want to create a panic’,” says Timmermann. There is a reason: forecasting a big El Niño would cause a spike in food prices. “But it may be better to have this reaction at an early stage, when farmers can still adapt, rather than later.”