Northern Australian temperature outlook
Issued 22 May 2013
There’s a greater than 60% chance of the June to August maximum temperature exceeding the long-term median maximum temperature over the Top End and the Cape York Peninsula (see map above). Probabilities exceed 80% over far north Cape York Peninsula and the Torres Straight. Such odds mean that for every ten years with similar climate patterns to those currently observed, about six to eight years would be expected to be warmer than average over these areas, while about two to four years would be cooler.
Conversely, there is a 35 to 40% chance of warmer than normal days over the southern NT and southern Queensland. In other words, there is a 60 to 65% chance of cooler than normal days over this area.
The chance that the average minimum temperature for June to August will exceed the long-term median minimum temperature is in excess of 60% over the northern NT, and the Cape York Peninsula.
Over the rest of north-eastern Australia, the chances of warmer or cooler night-time temperatures are roughly equal.
The tropical Pacific has remained ENSO-neutral since mid-2012. Climate models surveyed by the Bureau of Meteorology suggest sea surface temperatures in the tropical Pacific Ocean are likely to sit on the cool side of neutral during the next few months.
Four of five international models surveyed by the Bureau favour the development of a negative Indian Ocean Dipole (IOD) event sometime later in 2013. A negative IOD during the dry season increases the chances of above normal humidity levels and rainfall (and thus cloud amount) over central and northern Australia. Increased cloudiness reduces sunshine hours, and hence daytime temperatures, as well as acting as a blanket during the night, keeping night-time temperatures higher than average.
Warmer than normal ocean surface temperatures currently surround northern Australia. These warm ocean temperatures will influence air temperatures in tropical coastal areas the most.
How accurate is the outlook?
Outlook confidence is related to how consistently the oceans and broadscale climate affect northern Australian temperatures. During June to August, model accuracy shows the outlook for maximum temperatures to be moderately consistent over northern Australia.
The effect on minimum temperatures during this season is moderately consistent over most of northern Australia, except for near the NSW-Queensland border, and the northern NT, where the effect is weakly consistent.