Sea surface temperature (SST) anomalies (departures from
average) decreased in most of the equatorial Pacific during February (Fig.
1). By early March, near-average or slightly cooler-than-average SSTs were
observed everywhere east of 180°W,
with positive anomalies greater than +0.5°C
restricted to the region between
Indonesia and 180°W.
Since early December 2003, SST anomalies have
decreased in all of the Niņo
regions (Fig. 2).
The monthly 850-hPa zonal wind indices, OLR index, 200-hPa zonal wind
index, SOI and EQSOI have exhibited considerable intraseasonal variability
since late November in association with tropical Madden-Julian Oscillation (MJO)
activity. In spite of that variability, certain average atmospheric patterns
have become apparent since November. These include: 1) stronger-than-average
easterly winds between 160E and 150W (Fig. 3, top panel), and 2)
weaker-than-average convection (drier-than-average conditions) over the
central equatorial Pacific (Fig. 3, middle panel). These conditions are
consistent with the observed decrease in SST anomalies in the central
equatorial Pacific (Niņo 3.4 region, Fig. 2 and Fig.
A majority of the statistical and coupled model forecasts indicate near
neutral conditions in the tropical Pacific (Niņo
3.4 SST anomalies between -0.5°C
through May 2004. Thereafter, the forecasts show increasing spread and
greater uncertainty. Given the recent trends and observed oceanic and
atmospheric patterns discussed above, it is likely that ENSO-neutral
conditions will continue for the next 3-6 months.
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
thermal 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 the Forecast Forum
section of CPC's Climate Diagnostics Bulletin. To receive
an e-mail notification when the monthly ENSO Diagnostic Discussions are released, please send
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