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
El Niņo is expected to
strengthen and last through the Northern Hemisphere
weak El Niņo continued during August 2009, as sea surface temperature (SST)
remained above-average across the equatorial
Consistent with this warmth, the monthly values of the Niņo-region SST indices
were between +0.8°C to +1.0°C (Table T2). Subsurface oceanic heat
content (average temperatures in the upper 300m of the ocean) anomalies
continued to reflect a deep layer of anomalous warmth between the ocean surface
and the thermocline, particularly in the central Pacific (Fig. T17).
Enhanced convection over the western and central Pacific abated during
the month, but the pattern of suppressed convection strengthened over Indonesia
Low-level westerly wind anomalies continued to become better established
over parts of the equatorial
These oceanic and atmospheric anomalies reflect an ongoing weak El Niņo.
A majority of the model forecasts for
the Niņo-3.4 SST index (Figs.
F1-F13) suggest El Niņo will reach
at least moderate strength during the Northern Hemisphere fall (3-month Niņo-3.4
SST index of +1.0°C or greater). Many
model forecasts even suggest a strong El Niņo (3-month Niņo-3.4 SST index in
excess of +1.5°C) during the fall and winter, but current observations and
trends indicate that El Niņo will most likely peak at moderate strength.
Therefore, current conditions, trends, and model forecasts favor the continued
development of a weak-to-moderate strength El Niņo into the Northern Hemisphere
fall 2009, with the likelihood of at least a moderate strength El Niņo during
the winter 2009-10.
updates of oceanic and atmospheric conditions are available on the Climate
Niņo/La Niņa Current Conditions and Expert Discussions).