Synopsis: ENSO-neutral is favored into the Northern Hemisphere summer 2013.
During March 2013, ENSO-neutral continued, with slightly above average SSTs in the eastern portion of the basin (Fig. 1). Weekly values of all the Niño indices were between -0.5oC and +0.5oC during the month (Fig. 2). The oceanic heat content (average temperature in the upper 300m of the ocean) increased to near-average during the month (Fig. 3) as an area of above-average temperatures at depth moved eastward into portions of the eastern basin (Fig. 4). The Madden-Julian Oscillation (MJO) again contributed to increased atmospheric variability over the tropical Pacific. Low-level winds were near average, and upper-level winds were anomalously westerly across the equatorial Pacific. Convection was enhanced over the western equatorial Pacific and suppressed in the central basin (Fig. 5). Collectively, these features indicate the continuation of ENSO-neutral.
Most models forecast Niņo-3.4 SSTs to remain ENSO-neutral through the Northern Hemisphere fall (Fig. 6), with dynamical models tending to predict warmer conditions (0oC to 0.5oC) than the statistical models (-0.5oC to 0oC). There is less confidence in the forecasts for the last half of the year, partly because of the so-called "spring barrier," which historically leads to lower model skill beginning in late spring. Thus, ENSO-neutral is favored into the Northern Hemisphere summer 2013 (see CPC/IRI consensus forecast).
This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA's National Weather Service, and their funded institutions. Oceanic and atmospheric conditions are updated weekly on the Climate Prediction Center web
site (El Niño/La Niña Current
Conditions and Expert Discussions). Forecasts for the evolution of El Niño/La Niña are updated monthly in the
Forecast Forum section of CPC's Climate
Diagnostics Bulletin. The next ENSO Diagnostics Discussion is scheduled for 9 May 2013. To receive
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