C below normal in the
east-central Pacific and 2-3°C above normal in the western Pacific (Fig.
T17). This thermocline structure has been extremely persistent for the past 18
months , and remains consistent with the ongoing La Niņa conditions.
Tropical convection [as inferred from anomalous outgoing longwave radiation (OLR)] was
suppressed over the western and central equatorial Pacific during November, and enhanced
over Indonesia (Fig. T25). Convection has been suppressed
across the central equatorial Pacific since the onset of cold episode conditions in late
May 1998 (Fig. T8). Elsewhere, convection and rainfall were
also enhanced across northern and eastern Australia during November (Figs. T25, E4). In northeastern Australia,
area-averaged precipitation exceeded the 95th percentile, and totals were
nearly double the November climatological mean (Fig. E4).
Enhanced low-level (850 hPa) easterly winds persisted across the central and western
tropical Pacific during November (Fig. T20). Anomalous
easterlies have prevailed in this region since May 1998 (Fig. T7),
in association with ongoing La Niņa conditions. The upper-level atmospheric circulation
(200 hPa) in the Tropics and subtropics also remained consistent with cold episode
conditions, with well-developed upper-level troughs observed over the low-latitudes of the
central Pacific in both hemispheres and enhanced equatorial westerlies across the central
and eastern Pacific (Fig. T21).
The pattern of sea level pressure (SLP) anomalies during November was also consistent
with cold episode conditions, with positive anomalies observed across the tropical Pacific
and negative anomalies observed over Indonesia and the Indian Ocean (Fig.
T19). As a result, the Tahiti-Darwin Southern Oscillation Index (SOI) was 1.1 (Table T1, Fig. T1), and the equatorial
SOI increased to 2.2 (Fig. T2).
Editors Note: CDAS has been run for October and ran normally for November.
However, the CCA SST forecasts (Figs. F1-F2) continue to be omitted, since the software
necessary to run these products has not been transferred to the new computing environment.