Current atmospheric and oceanic conditions in the tropical
Pacific are near average and do not support the development of either
La Niņa or El Niņo
in the next few months. Equatorial sea-surface temperature anomalies greater
than +0.5°C persisted in the region west of the date line, while near-zero anomalies
dominated the equatorial Pacific east of 150°W (Fig.
1). During August very little net change was observed in the SST
anomalies in the Niņo regions (Fig. 2).
Beginning in late May positive equatorial upper-ocean temperature
departures spread eastward into the central and eastern Pacific (see Fig. 3
for evolution during August 2003). This evolving subsurface pattern was
associated with an eastward propagating oceanic Kelvin wave, resulting from
a period of weaker-than-average easterlies in the central equatorial Pacific
that occurred during late May and early June. SST anomalies in the Niņo
3.4 and Niņo 3 regions (Fig. 2) increased during early-June through early July, but then
decreased during the last half of July and remained fairly steady during
August.
Some atmospheric indices, such as the Tahiti-Darwin SOI, and
central equatorial Pacific low-level (850-hPa) zonal wind and OLR, have
displayed considerable month-to-month variability since May 2003 and no
consistent trend towards either La Niņa or El Niņo
.
A majority of the statistical and coupled model forecasts indicate near
neutral conditions (Niņo 3.4 SST anomalies between -0.5°C and +0.5°C) for
the remainder of 2003 and early 2004. This is consistent with current
conditions and the lack of any consistent trends in the suite of oceanic and
atmospheric indices.
This discussion is a consolidated effort of NOAA and its
funded institutions. Weekly updates for SST, 850-hPa wind, OLR and features of the equatorial subsurface
temperature structure are available on the Climate Prediction Center web page at
http://www.cpc.ncep.noaa.gov (Weekly Update). Forecasts for the evolution of
El Niņo/La Niņa are updated monthly in CPC's Climate Diagnostics Bulletin Forecast Forum. To receive
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