Equatorial surface and subsurface temperatures were
slightly warmer than average throughout most of the Pacific during September
(Fig. 1 and Fig. 2, respectively). Equatorial SST anomalies greater than +0.5°C
(~1°F) persisted
in the region west of the date line during September, and developed over
most of the region between the date line and 120°W
during the last half of the month (Fig. 3). This anomalous warming east of
the date line was associated with a brief weakening of the easterlies that
occurred during 19-25 September (Fig. 4). Generally, atmospheric conditions
in the tropical Pacific have been near average in recent months, with no
significant trends that would support large-scale anomalous warming or
cooling of SSTs in that region. Thus, slightly warmer-than-average
conditions are likely to persist for the next several months.
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. However, over the past few months
there has been a trend in the suite of forecasts towards somewhat warmer
conditions, consistent with observations. Thus, it is likely that slightly
warmer-than-average conditions will persist in the equatorial Pacific
through the Northern Hemisphere winter of 2003-04.
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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