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 October 2008, as equatorial sea surface temperatures
(SSTs) were near-average across much of the
, except for small
areas of below-average SSTs in the east-central Pacific and off the coast of
T18). Correspondingly, the latest monthly SST
index values were near-average in all Niņo regions (Table
oceanic heat content anomalies (average temperatures in the upper 300m of the
ocean) became less negative due to the eastward shift of positive temperature
anomalies at thermocline depth to ~160°W, but anomalies remained negative in
the eastern half of the Pacific (Fig. T17).
atmospheric winds and convection patterns exhibited a high degree of
week-to-week variability across the tropical Pacific during October in response
to the Madden-Julian Oscillation (MJO) (Figs. T11, T12). The cumulative effects of the MJO were 1) above-average convection over
, and 2) enhanced
low-level easterly winds, enhanced upper-level westerly winds, and suppressed
convection over the western and central equatorial Pacific (Figs. T20, T21,
Overall, the ocean-atmosphere system remains consistent with ENSO-neutral
majority of the SST forecasts 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.
Several dynamical models suggest the development of a La Niņa during
Northern Hemisphere Winter 2008-09. This
outcome becomes more likely if the current MJO were to stall in a location that
favors enhanced low-level easterlies and increased upwelling in the east-central
and eastern Pacific. However, it is
rare for La Niņa to develop late in the year.
Therefore, based on current atmospheric and oceanic conditions and recent
trends, 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).