Tropical Highlights
SEPTEMBER 2010
Forecast Forum
Negative
sea surface temperature (SST) anomalies continued to strengthen across the
equatorial Pacific Ocean during September 2010 (Fig.
T18).
The monthly Niņo indices were -1.6°C for both Niņo
3.4 and Niņo
1+2 regions (Table T2,
Fig. T5).
Consistent with this evolution, the oceanic thermocline (measured by the
depth of the 20°C
isotherm) remained much shallower than average across the central and eastern
equatorial Pacific (Figs. T15 and
T16), with sub-surface temperatures
reaching 1°C to 6°C
below average in these regions (Fig. T17).
Also
during September, equatorial low-level easterly trade winds and upper-level
westerly winds remained stronger than average over the western and central
Pacific (Table T1,
Figs. T20 and
T21). This wind pattern was associated with
enhanced convection over Indonesia and suppressed convection across the western
and central equatorial Pacific (Figs. T25
and E3). Collectively, these
oceanic and atmospheric anomalies reflect a strengthening of La Niņa
conditions.
Elsewhere,
enhanced convection (above-average rainfall amounts) was observed observed over
the North Atlantic/Caribbean Sea and across the west African monsoon region
during September (Figs. T25
and E3),
which is consistent with a very active Atlantic hurricane season.
For
the latest status of the ENSO cycle see the ENSO Diagnostic Discussion at:
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.html
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