CPC and the contributors to the Forecast Forum caution potential users of
this predictive information that they can expect only modest skill.
Alert System Status: La
Conditions are favorable for a transition to La
Niña conditions during June – August 2010.
Niño dissipated during May 2010 as positive surface temperature (SST) anomalies
decreased rapidly across the equatorial Pacific Ocean and negative SST anomalies
emerged across the eastern half of the Pacific (Fig. T18). All of
the Niño indices decreased between 0.5°C to 1.0°C during the month (Table
Since the end of February, subsurface heat content anomalies (average
temperatures in the upper 300m of the ocean) have decreased steadily.
Below-average temperatures have strengthened at depth and currently
extend to the surface in parts of the eastern Pacific (Fig. T17). Also
during May, enhanced convection persisted over Indonesia, while the area of
suppressed convection strengthened and expanded over the tropical central
Pacific (Fig. T25). The low-level easterly
trade winds strengthened over the western and central equatorial Pacific, and
anomalous upper-level westerly winds prevailed over the east-central Pacific (Figs.
Collectively, these oceanic and atmospheric anomalies reflect the demise
of El Niño and return of ENSO-neutral conditions.
majority of models predict ENSO-neutral conditions (between -0.5°C to +0.5°C
in the Niño-3.4 region) through early 2011 (Figs.
over the last several months, a growing number of models, including the NCEP
Climate Forecast System (CFS), indicate the onset of La Niña conditions during
There is an increasing confidence in these colder model forecasts, which
is supported by recent observations that show cooling trends in the Pacific
Ocean and signs of coupling with the atmospheric circulation.
Therefore, conditions are favorable for a transition to La Niña
conditions during June-August 2010.
updates of oceanic and atmospheric conditions are available on the Climate
Niño/La Niña Current Conditions and Expert Discussions).