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: El
are favorable for a transition from ENSO-neutral to El Niņo conditions during
June − August 2009.
persisted across the equatorial
during May 2009.
However, sea surface temperatures (SST) departures increased for the fifth
consecutive month, with above-average temperatures extending across the
by the end of May (Fig.
Accordingly, the monthly SST indices ranged between +0.3° to +0.6°C in
all four Niņo regions (Table T2).
Subsurface oceanic heat content anomalies (average temperatures in the
upper 300m of the ocean) also continued to increase in response to a large area
of above-average temperatures (+1° to +3°C) near thermocline depth (Fig.
surface and subsurface oceanic anomalies typically precede the development of El
early 2007 through April 2009, enhanced low-level easterly winds persisted near
the Date Line, interrupted only briefly by Madden- Julian Oscillation (MJO)
activity (Fig. T20). However, during May 2009,
both the lower-level equatorial winds were near-average in that region despite
the absence of the MJO. Also,
suppressed convection expanded westward along the equator from the Date Line to
The recent oceanic and atmospheric anomalies are consistent with ENSO-neutral
conditions, but also reflect the evolution towards a potential El Niņo.
continues to be considerable spread in the model forecasts for the Niņo-3.4
region (Figs. F1-F13). All statistical models
will continue for the remainder of 2009. However,
most dynamical models, including the NCEP Climate Forecast System, predict the
onset of El Niņo during June − August 2009.
Current observations, recent trends, and the dynamical model forecasts
indicate that conditions are favorable for a transition from
to El Niņo conditions during June − August 2009.
updates of oceanic and atmospheric conditions are available on the Climate
Niņo/La Niņa Current Conditions and Expert Discussions).