Seasonal Climate Outlook March - May 2007
The Seasonal Outlook released by the Bureau of Meteorology on 22 February 2007, for the March to May period, shows neutral odds (i.e. around 50%) across the State of exceeding the median rainfall.
The temperature outlook for March to May shows that the chances of exceeding the median maximum temperature are 45-50% across the State.
All the main indicators show that the 2006/07 El Niño event is over. All the main ENSO indicators show that neutral conditions have returned to the Pacific Basin. Along the equator, sea-surface temperatures are cooling rapidly and have been below their El Nino thresholds for over a month. The Trade Winds have been close to, or somewhat stronger than, normal since December, and the SOI has been neutral for three of the past four months. Computer models indicate further cooling in the Pacific, with a La Nina event not being out of the question.
The chance of a La Nina event developing in 2007 is thought to be higher than the long-term average (which is about one in five) because:
- they have a tendency to follow El Nino;
- the El Nino has decayed somewhat earlier than normal, thereby giving time for a La Nina to begin developing during the critical March-June period;
- a large pool of cold sub-surface water has developed in the central to eastern tropical Pacific Ocean.
Overall, there is “cautious optimism” that there will be a general easing of dry conditions in drought-affected areas over the next one to two seasons. However, this is the time of year when predictability of the climate system is at its lowest.
The Bureau’s next seasonal outlook is expected on 26 March 2007.