Northern Australian temperature outlook
Issued 28 August 2013
The chances of the spring maximum temperature exceeding the long-term median maximum temperature are greater than 60% over the tropical north (see map above). Such odds mean that for every ten years with similar climate patterns to those currently observed, about six to eight spring periods would be expected to be warmer than average over these areas, while about two to four years would be cooler.
For southern Queensland and most of the southern NT there is a near equal chance of warmer or cooler than average daytime temperatures.
The chance that the average minimum temperature for spring will exceed the long-term median minimum temperature is in excess of 60% over the northern half of the continent, with the exception of parts of southeast Queensland being less than 60%. Probabilities exceed 80% over the tropical northern coasts.
The negative Indian Ocean Dipole (IOD) event that has been influencing Australian climate since mid-May has weakened over the past four weeks. Despite this, sea surface temperature patterns continue to be consistent with a negative dipole event. The majority of climate models expect this negative IOD event to persist until mid-spring. A negative IOD during this period increases the chance of higher humidity over parts of northern Australia which would also tend to increase minimum temperatures.
The tropical Pacific has remained ENSO-neutral since mid-2012. The dynamical seasonal outlook model suggests ENSO-neutral conditions will remain for the rest of 2013. This means there is no strong shift in the odds from the tropical Pacific, and is reflected to some degree in the temperature outlook, with much of southern Queensland and the southern NT having odds close to 50% for maximum temperatures.
How accurate is the outlook?
Outlook accuracy is related to how consistently the oceans and broadscale climate affect Australian temperatures. During the September to November period, historical accuracy shows the outlook for maximum temperatures to be moderately consistent over the Top End of the NT, and most of Queensland apart from small regions across northern Queensland.
For minimum temperatures, historical accuracy is moderately consistent over southern parts of the NT, southwest Queensland and parts of the tropical north, elsewhere the outlook is only weakly to very weakly consistent.