El Niño / La Niña Current Conditions

The latest assessment of sea surface temperatures in the tropical Pacific by the Climate Prediction Center indicates that El Niño conditions are occurring.

As seen in the image below, the current anomalies do show some of the classic El Niño setup with warmer than normal sea surface temperatures extending from South America westward into the central Pacific Ocean.

A good way to monitor the El Niño/Southern Oscillation (ENSO) is through the use of the Multivariate ENSO Index (MEI). This index takes into account six variables including the sea-level pressure, zonal and meridional components of the surface wind, sea surface temperature, surface air temperature, and total fraction of the sky covered by clouds. Positive values of the MEI represent the warm ENSO phase (El Niño) while the negative MEI values represent the cold ENSO phase, (La Niña). As seen below the MEI is currently positive indicating El Niño conditions, albeit well short of the 1982-83 and 1997-98 episodes.

Comparing the current MEI to the seven strongest El Niño events since 1950, we see that the most recent MEI value has decreased by just over 0.3 standard deviations, but still stands at +0.98 just barely below the moderate El Niño threshold. Compared to the seven historic big El Niño's, the current event had made up for a delayed start (by about one to two months) by continuing to grow well into the boreal fall season. It remains to be seen whether its recent drop will continue further, "removing it from competition", or whether it will rebound in the near future.