La Ni±a weaker, may be gone by summer

Meteorologist Dr. Jeff Masters, in a WunderBlog repost.

A significant shift is occurring in the Equatorial waters of the Eastern Pacific off the coast of South America, where the tell-tale signs of the end to the current La Ni±a event are beginning to show up.

A borderline moderate/strong La Ni±a event has been underway since last summer, with sea surface temperatures (SSTs) about 1.5°C below average over a wide stretch of the Equatorial Pacific. These cool SSTs have altered the course of the jet stream and have had major impacts on the global atmosphere. The La Ni±a has been partially responsible for some of the extreme flooding events in recent months, such as the floods in Australia, Sri Lanka, and Colombia. La Ni±a is also largely to blame for the expanding drought over the southern states of the U.S.

But in the last few weeks, SSTs in the Equatorial Pacific have undergone a modest warm-up, and these temperatures are now about 1.2°C below average. A region of above-average warmth has appeared immediately adjacent to the coast of South America–often a harbinger of the end to a La Ni±a event. An animation of SSTs since late November shows this developing warm tongue nicely. Springtime is the most common time for a La Ni±a event to end; since 1950, half of all La Ni±as ended in March, April, or May. The weakness displayed by the current La Ni±a event has prompted NOAA’s Climate Predictions Center to give a 50% chance that La Ni±a will be gone by June. If La Ni±a does rapidly wane, this should help reduce the chances for a continuation of the period of high-impact floods and droughts that have the affected the world in recent months.

Figure 1. A comparison of the the departure of sea surface temperature (SST) from average between this week and two months ago shows that a tongue of warmer-than-average waters has appeared off the coast of South America, possibly signaling the beginning of the end of the current La Ni±a event. Image credit: NOAA Climate Prediction Center.

What does this mean for hurricane season?
As many of you know, the phase of the El Ni±o/La Ni±a is critical for determining how active the Atlantic hurricane season is. La Ni±a or neutral conditions promote very active Atlantic hurricane seasons, while El Ni±os sharply reduce Atlantic hurricane activity, by increasing wind shear. Will the probable demise of La Ni±a this spring allow an El Ni±o to take its place by this fall? Well, don’t get your hopes up. Since 1950, NOAA’s Climate Prediction Center records that there have been sixteen La Ni±a events during February (26% of all years.) In half of those years, La Ni±a was still active during the August – September – October peak of Atlantic hurricane season, six (38%) transitioned to neutral conditions, and only two (12%) made it all the way to El Ni±o. So historically, the odds do not favor a transition to El Ni±o by hurricane season. The latest set of computer model forecasts of El Ni±o/La Ni±a (Figure 2) also reflect this. Only two of the sixteen models predict El Ni±o conditions by hurricane season.

Figure 2. Predictions made in January 2011 of the evolution of El Ni±o/La Ni±a over the coming year shows that only two of the sixteen models predict El Ni±o conditions by hurricane season, while four predict La Ni±a and ten predict neutral conditions. Image credit: Columbia University IRI.

— Dr. Jeff Masters.

16 Responses to La Ni±a weaker, may be gone by summer

  1. Raul M. says:

    Those in good drainage areas might find
    Safety in digging under concrete foundations..
    You know out of sight out of mind.
    Nice survival strategy for the virtual
    Warming Tour.

  2. Sou says:

    Similar to what BoM has been stating, from the southern hemisphere:

    The La Niña event which has dominated the Australian climate for the past nine months is showing signs of weakening. Pacific Ocean temperatures, most notably below the surface, have warmed, while atmospheric indicators such as the Southern Oscillation Index (SOI), trade winds and cloud patterns have eased from their respective peaks in early January.

    These observations are consistent with both the life cycle of past La Niña events and long-range climate models, which show the Pacific gradually warming during the southern autumn of 2011. All available climate models suggest further weakening of the La Niña is likely through autumn, with most indicating a return to neutral conditions by winter 2011. However, there remains some risk that the event may reform after autumn.

    As at 16 Feb 2011:

  3. Some European says:

    I think figure 2 shows that we can’t predict ENSO conditions just yet. It doesn’t seem more convincing than my daily horoscope.
    Experts, feel free to explain where I went wrong.

  4. Wyoming says:


    What are you up to?

    You admit that you have no expertise yet you seem to want either some attention or you have an unstated agenda.

    So, if none of the experts from NOAA or others who may read your blip decide to waste their time rebutting you then what? Are you going to take that and run off to some other blog and claim that you checked with the “experts” at Climate Progress and they did not refute your “analysis” therefore it must be correct?

    Equating astrology to science means you think like an astrologer. Not much chance of credibility there. If you have a rational point, try and make it.

  5. paulm says:

    Chances are that this atlantic hurricane season is going to be off the charts…

  6. From Peru says:

    There is a huge mass of warm water in the Western Pacific (on the Asian/Australian side), the result of heat accumulation during La Niña:

    Now that La Niña is weakening, I guess that all this warm water will be discharged towards the East Pacific in the coming months, probably triggering an El Niño.

    I have no crystal ball, but the amount of warm water accumulated in the Western Pacific make me guess that the El Niño will be huge.

  7. Colorado Bob says:

    China’s weather forecasters reluctant to confirm rumours of rain

    As China is gripped by its worst drought for 60 years, stakes are high for meterologists, who are reticent about the forecast

  8. Esop says:

    #6 (Peru):
    Let us hope that you are correct regarding the El Nino. The sooner that we will have a monster year, the better, as that will make more people realize what is going on. As a bonus, the deniers will be busy with backpeddling from their global cooling lies, as well as trying to explain all the extreme weather events as “natural”. This means they will have less free time to harass the scientists. Come to think of it, they must be quite busy these days, with extreme 500 year events happening on an almost weekly basis, all over the globe.

  9. Richard Brenne says:

    Wyoming (#4) – Like you, Some European has made many excellent comments in many areas here. He’s one of us, in fact he’s probably our commenter MVP for his age (26), so go easy, please.

    I don’t have a dog in this fight (an expression I’m told Michael Vick no longer uses), but compared to human fossil-fuel burning being the primary forcing of global warming, ENSO predictions, while getting better, are notoriously tricky.

    And speaking of astrology, my favorite horoscope, and the one that I feel should be for every sign every day for all eternity, came from the Onion and said: “Certain shortcomings in your family and educational background lead you to believe that there is a relationship between the alignment of celestial bodies and your everyday life.”

    But then the Milankovitch cycles are largely about the alignment of celestial bodies (especially Jupiter, making Earth’s orbit go from more circular to more elliptical) and ice ages or interglacials have an impact on your everyday life, so I don’t know what to believe.:)

  10. question says:


    I agree with #9. Go easy on #3, the comment was reasonable. Figure 2 *does* show that the scatter is extraordinarily large. Which is fine. A short term variation is not climate. And of course even legitimate science has a range of predictions on climate. That’s what differentiates real science from the deniers: the deniers already “know” the answer and admit of no uncertainty. Real science admits there is uncertainty but quantifies it. In the current situation the uncertainty about our global climate predictions is small enough that BAU is ruled out at many sigma… if we don’t do something the likelihood of major climate change is overwhelming.

  11. From Peru says:

    Esop says:
    February 23, 2011 at 12:30 pm
    #6 (Peru):

    “Let us hope that you are correct regarding the El Nino”

    Well, big El Niños are disatrous to Peru. Last time, in 1998, several cities were buried and destroyed by mudflows and extreme rainfall, some as south as city of Ica. In Lima, the raging waters of the Rimac River almost reached the Main Square … they missed it by a few hundred meters.

    On the other side of the Andes Mountains, the Amazon Rainforest suffered one of its worst droughts. Droughts also affected the Indonesian Rainforest, where 1/3 of the rainforest was set on fire.

    As a result of the El Niño-induced ocean warming, droughts and fires, the rate of CO2 increase in 1998 was the highest on record: 2.9 ppm/year. 2010, also an El Niño year, saw the second highest on record rate of CO2 increase: 2.76 ppm/year.

    If 2012 is a year of a monster El Niño, not only Hansen prediction will be right: my country will be devastated, the Amazon and Indonesia will dry and burn, massive coral bleaching will hit the coral reefs worldwide (like in 1998 and 2010, only worse) and the rate of CO2 increase (that is also on a long term rise thanks to the crazy energy policy of China) will be at recors highs, breaking the 3 ppm/year mark.

    The only good think of all of this possible disater is that a lot of people (I hope) will be scared to death by extreme weather, and the mith of “global cooling” will melt like the ice on Greenland. Let’s hope that the public opinion reaction to something like this will not be wasted like after the BP monster oil spill and the 2010 extreme weather events.

  12. Wyoming says:

    9 & 10

    Ok, I’ll take your word for it. Just poor wording then. My bad.

    The comment just clearly fit a rhetorical pattern, that repeats all over the place, used by deniers and other trouble makers.

    I am not immune to wording things such that I give the wrong impression of what I am trying to say also.


  13. Sou says:

    Just going by the articles in the press, and the reaction to them, people seem to be more persuaded of global warming by extremes from La Nina events more so than from extremes from El Nino events.

    Or perhaps it’s from extreme precipitation events – flooding, mudslides, snowfalls etc than from heat extremes, wildfires, dried up water supplies and prolonged drought.

    Maybe it’s because drought is less felt in large cities (except as water restrictions and the occasional smoke blanket drifting from fires far away), while extreme precipitation affects everyone, regardless of where they live.

  14. Michael says:

    From Peru (#6) –

    The heat buildup in the western Pacific right now looks a lot like in early 1997, only about a month behind, still cooler in the eastern Pacific but rapidly warming:

    Of course, a stronger El Nino is more likely(?) to be followed by a long La Nina (as in 1998-2001) because it takes longer to recharge the lost heat.

  15. riverat says:

    James Hansen has said he expects 2012 to be a record setting year.

  16. Richard Brenne says:

    Wyoming (#12) – Thanks for your kind words. When was the last time anyone heard a Republican admit a mistake? Lincoln? (By the way, Republicans identifying Lincoln as one of their own is kind of like lawyers claiming Gandhi. Technically both can, but now their spirit is often the opposite of either.)

    So Some European, we cool (I know you are)?