CPC and the contributors to the Forecast Forum caution potential users of
this predictive information that they can expect only modest skill.
ENSO-neutral conditions are
conditions continued during September 2008, as sea surface temperatures (SSTs)
remained near-average in the east-central equatorial
SSTs remained slightly below-average in the central Pacific, and slightly
above-average in the eastern Pacific (Fig.
From west to east, the monthly SST index values range
from −0.4°C in the Niņo-4 region
to +0.7°C in the Niņo 1+2 region (Table T2). The subsurface oceanic heat
content (average temperatures in the upper 300m of the ocean) continued to
decrease in response to the strengthening of negative temperature anomalies at
thermocline depth in the east-central Pacific (Fig. T17).
ENSO-neutral conditions have been in place since June 2008, the atmospheric
circulation over the western and central tropical Pacific continues to reflect
lingering aspects of La Niņa. The MJO accentuated this signal during
early-to-mid September, and suppressed it during the latter part of the month.
The combined monthly average signal featured enhanced low-level easterly winds
and upper-level westerly winds in the central Pacific (Figs.
T20 and T21), with convection enhanced over
and suppressed over
the central Pacific (Fig. T25). Overall, the
ocean-atmosphere system remains consistent with ENSO-neutral conditions.
of the dynamical and statistical SST forecasts for the Niņo
3.4 region indicate a continuation of ENSO-neutral
conditions (−0.5°C to 0.5°C in the Niņo-3.4 region) into the first half
of 2009 (Figs. F1- F13).
While the model spread continues to include possibilities ranging from El
Niņo to La Niņa, the recent decrease in subsurface and surface temperatures
favors a return to La Niņa over the development of El Niņo. However, based on
current atmospheric and oceanic conditions, recent trends, and model forecasts,
ENSO-neutral conditions are expected to continue into early 2009.
updates of oceanic and atmospheric conditions are available on the Climate
Niņo/La Niņa Current Conditions and Expert Discussions).