BOM ENSO Update

[AussieMark]

Since early August, key ENSO indicators have been consistent with the development phase of an El Niño event. These include sustained negative values of the Southern Oscillation Index (SOI), warmer than normal tropical Pacific Ocean temperatures and a marked decrease in the strength of the Trade Winds. During the past fortnight, weekly surface temperatures have risen above El Niño thresholds in the western and eastern Pacific, while reaching a level just marginally below in the central Pacific.

However, to qualify as an El Niño event, tropical Pacific temperatures would need to persist at their present weekly levels for around another four months, accompanied by a continued weakening of the Trade Winds and above average central Pacific cloudiness. Most computer models indicate continued warming in the Pacific, which implies a probable strengthening of the developing El Niño pattern.

The observed below average rainfall during late autumn and winter across Australia's southern half, especially in the southeast and southwest, is also consistent with the early stages of an El Niño event. Furthermore, even if El Niño thresholds are not reached across the range of indicators, a warming Pacific and a low SOI bias the climate towards being drier and warmer than average across eastern and northern Australia for the remainder of 2006. This is reflected in the spring outlooks for rainfall and temperature.



In Brief

* Since early August, the changes in all key ENSO indicators are consistent with an incipient El Niño.
* Equatorial Pacific SSTs have continued to warm. Weekly values of SSTs in the west and east are now over El Niño thresholds.
* Subsurface temperatures have also increased. A Kelvin Wave of very much increased temperatures is in the eastern Pacific, propagating towards the South American coast.
* The SOI, though still negative, has risen to a current (10th September) 30-day value of −6.
* The Trade Winds were much weaker than average in the second half of August west of the dateline, though they strengthened in early September and are currently only slightly weaker than average.
* Cloudiness near the dateline along the equator has been a little above average so far in September. In general, cloudiness has been increasing in this area since late May.
* Most computer models predict warming in the Pacific during the rest of 2006, but with temperatures in the neutral range during the southern summer. However, some haven't yet factored in the significant developments of August.

Source

[Jim Hughes]

Since early August, key ENSO indicators have been consistent with the development phase of an El Niño event. These include sustained negative values of the Southern Oscillation Index (SOI), warmer than normal tropical Pacific Ocean temperatures and a marked decrease in the strength of the Trade Winds. During the past fortnight, weekly surface temperatures have risen above El Niño thresholds in the western and eastern Pacific, while reaching a level just marginally below in the central Pacific.

However, to qualify as an El Niño event, tropical Pacific temperatures would need to persist at their present weekly levels for around another four months, accompanied by a continued weakening of the Trade Winds and above average central Pacific cloudiness. Most computer models indicate continued warming in the Pacific, which implies a probable strengthening of the developing El Niño pattern.

The observed below average rainfall during late autumn and winter across Australia's southern half, especially in the southeast and southwest, is also consistent with the early stages of an El Niño event. Furthermore, even if El Niño thresholds are not reached across the range of indicators, a warming Pacific and a low SOI bias the climate towards being drier and warmer than average across eastern and northern Australia for the remainder of 2006. This is reflected in the spring outlooks for rainfall and temperature.



In Brief

* Since early August, the changes in all key ENSO indicators are consistent with an incipient El Niño.
* Equatorial Pacific SSTs have continued to warm. Weekly values of SSTs in the west and east are now over El Niño thresholds.
* Subsurface temperatures have also increased. A Kelvin Wave of very much increased temperatures is in the eastern Pacific, propagating towards the South American coast.
* The SOI, though still negative, has risen to a current (10th September) 30-day value of −6.
* The Trade Winds were much weaker than average in the second half of August west of the dateline, though they strengthened in early September and are currently only slightly weaker than average.
* Cloudiness near the dateline along the equator has been a little above average so far in September. In general, cloudiness has been increasing in this area since late May.
* Most computer models predict warming in the Pacific during the rest of 2006, but with temperatures in the neutral range during the southern summer. However, some haven't yet factored in the significant developments of August.

Source

One will always be more accurate over the long run by using climatology but it also leaves open the door for a big time bust. This has the potential to be one of those times. I have to wonder at what point do they admit the models are lost here. They have hinted at this but they have never said . " Hey we need to toss them out the window here."...which is what I would have done a while ago.