IDD20730 Australian Government Bureau of Meteorology Northern Territory Darwin RSMC - Australia

El Nino-Southern Oscillation Update
The 30-day Southern Oscillation Index [SOI] to November the 14th was -15. Contributing pressure anomalies were +0.7 hPa at Darwin and -1.7 hPa at Tahiti. The monthly SOI for October was -15, and its 5-month running mean [centred on August] was -3. After many months near neutral, the SOI fell rapidly in October, and has remained strongly negative over the past few weeks. This is in-line with what is expected during an El Nino event.

Sea surface temperatures [SST] remain greater than normal across almost the entire equatorial Pacific Ocean, with anomalies greater than 2.0 C evident in the equatorial Pacific east of the dateline. Sub-surface temperatures along the central equatorial Pacific Ocean have warmed in October and November, with weekly anomalies exceeding 4.0C above average in an area between 150W and 110W. SSTs across northern Australia and the Maritime Continent are mixed but generally close to normal. Equatorial easterly winds have strengthened in the western Pacific ahead of the approaching Madden-Julian Oscillation [MJO], whilst remaining close to the long-term mean elsewhere. El Nino and Southern Oscillation [ENSO] predictors suggest that the current El Nino conditions are likely to persist into early 2010. See the Bureau's "ENSO Wrap-Up" at www.bom.gov.au/climate/enso/ which includes a compilation of ENSO computer model predictions.

Intra-Seasonal Patterns
During the northern hemisphere summer, the MJO was generally weak and inconsistent.

Towards the end of October and start of November we saw enhanced convection in the western and central Indian Ocean. Convection is now progressing eastward into the Maritime Continent region, indicative of the MJO moving into this area. This convective signal appears to be weakening as it moves into the Indonesian region however. Generally, forecast models predict the MJO signal will continue to deteriorate over the coming week as it progresses east across the Maritime continent, however there is still a chance of increased shower and thunderstorm activity over this region in the latter half of November.

Although an active MJO pulse increases the likelihood of tropical cyclogenesis and monsoon activity in the Australian region, it is considered a low probability for the end of November.

* Darwin RSMC chart area extends from 40S to 40N, 70E to 180
The Weekly Tropical Climate Note is updated each Tuesday by about 0330 UTC.
http://www.bom.gov.au/climate/tropnote/tropnote.shtml
For more information please contact climate.tropical@bom.gov.au