December 2008

WMO El Niño/La Niña Update
(21 November 2008)

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Current situation and outlook

  storm ahead
   

Taking the Pacific basin as a whole, near-neutral El Niño-Southern Oscillation conditions have prevailed since mid-year. Any slight increased risk that an El Niño might develop late in 2008 has receded, as surface waters remain only marginally warmer than normal in the central and eastern equatorial Pacific and no strongly organized large-scale subsurface warming has emerged.

Forecast models are in general agreement that near-neutral conditions will prevail through the remainder of 2008 and that there is no substantial risk of El Niño or La Niña through the remainder of 2008 and indeed into early 2009. However, confidence in projections into early 2009 carry increased uncertainty. Expert interpretation refrains from drawing any robust conclusions at this time about the likelihood of El Niño or La Niña development during the historically favoured time of year of March-May. Thus, over the next months, tropical Pacific conditions and forecast models will be closely monitored for any signs of possible changes in early 2009.

In the current absence of El Niño or La Niña conditions in the Pacific, users should not lower their guard against the possibility of risks of climate extremes during the next few months. Users must keep in mind that many climate extremes can develop independently of El Niño and La Niña, under the influence of other region-specific systems. Users should therefore consult their respective National Meteorological and Hydrological Services and regional climate institutions for more specific climate outlooks and follow-up updates.

In summary:

  • Near-neutral conditions have prevailed since mid-year 2008.
  • Models and expert interpretation are in good agreement that near-neutral conditions are expected to continue at least to the end of 2008 and indeed into early 2009.
  • March-May is historically a preferred time for El Niño or La Niña development, so observations and forecasts for March-May 2009 will be carefully monitored over the coming months for any possible signs of development.

It is important to appreciate that periods like this one, when El Niño and La Niña conditions are absent, do not necessarily herald fewer climate extremes. It is still possible for such extremes to develop under the influence of region-specific systems. Users should therefore continue to deploy good risk management practices and consult local and regional climate outlooks.

The situation over the tropical Pacific will continue to be carefully monitored and timely updates of any new developing anomalies provided. More detailed interpretations of regional climate fluctuations will be generated routinely by the climate forecasting community over the coming months and will be made available through the National Meteorological and Hydrometeorological Services.

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