#30 Postby cycloneye » Thu Feb 24, 2005 6:45 am
COMMENTARY:
The tropical Pacific has continued to gradually cool over the past month, particularly in western areas where the positive anomalies had been strongest. The current situation is therefore neutral. A majority of computer forecast models in the table above predict neutral conditions in the tropical Pacific in both July and October 2005. However, most models will not have factored into their calculations a strong westerly wind burst in February that has produced +5°C anomalies on the thermocline around the dateline. A down-welling Kelvin wave will propagate these anomalies to the east during the next two to three months.
The POAMA model, run at the Bureau of Meteorology, generates a new forecast every day for the following eight months based on the latest observations. The mean of the most recent ensemble of POAMA model runs suggest that central to eastern equatorial Pacific (NINO3) temperatures will increase steadily during the southern autumn and winter, but remain below the 0.8°C El Niño threshold up until at least October. So POAMA is not indicating warming in the Pacific to the same level as it did a month ago, but this may be due to the fact that it has the initial conditions about 0.5°C cooler than reality. The frequency of POAMA model runs persisting in the neutral range is in the majority for each month up to and including October.
From the 30 runs of POAMA between 24th January and 22nd February, the distribution of NINO3 temperature anomalies averaged over JULY is as follows:
–0.8°C to zero: 0% (Neutral)
zero to +0.8°C: 68% (Neutral)
above +0.8°C: 32% (Warm)
And similarly for OCTOBER the results are:
–0.8°C to zero: 12% (Neutral)
zero to +0.8°C: 52% (Neutral)
above +0.8°C: 36% (Warm)
Similar data for other months can be accessed by following the "POAMA" link in the table above. Of the eleven remaining international models, three reach warm (El Niño) conditions sometime between March and May. Overall, a majority (9 to 3) of the models favour neutral conditions in five months' time, and also in eight months' time (6 to 1) with the one in this case being cool.
The models for ENSO update came out today and they haved not catched up with the latest WWB burst.But let's see if that burst is strong enough to trigger a warm episode of el nino although as Mike said not of the dimensions of the 1997 one by any means.
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