|Southeastern Aust Seasonal Rainfall Outlook: probabilities for November 2008 to January 2009, issued 28th October 2008|
Neutral rainfall outlook indicated for southeastern Australia
For southeastern Australia, the outlook for total rainfall during November to January shows no moderate or strong shifts in the odds favouring either wetter or drier than normal conditions. In other words, the chances of being wetter than normal are about the same as the chances of being drier. The one exception is over the far northeast of SA where the odds have shifted in favour of a wetter than average season.
The chances of November to January totals exceeding the 3-month median rainfall are a little over 60% over far northeast SA (see map). This means for every ten years with ocean patterns like the current, about six are expected to be wetter than average in this part of the country, while about four are drier. Over the rest of SA, NSW, Victoria and Tasmania the chances of exceeding the seasonal median are mostly between 45% and 60%.
The pattern of seasonal rainfall odds for southeastern Australia are from combined contributions from the Indian and Pacific Oceans. In northeast NSW the contributions tend to cancel: the warm Indian Ocean promotes above average falls while the present Pacific Ocean pattern favours drier than average conditions.
Outlook confidence is related to how consistently the Pacific and Indian Oceans affect Australian rainfall. During the November to January period, history shows this effect to be moderately consistent across much of Tasmania and NSW, and in patches across Victoria and far northern SA (see background information). In these areas where outlook confidence is not high caution should be used when interpreting these outlooks.
The 30-day value of the Southern Oscillation Index (SOI) was +14 as at 25 October. Computer models indicate a continuation of neutral conditions across the equatorial Pacific Ocean as the most likely outcome during the forecast period. For routine updates and comprehensive discussion on any developments please see the ENSO Wrap-Up.
Click on the map above for a larger version of the map. Use the reload/refresh button to ensure the latest forecast map is displayed.
More information on this outlook is available Monday to Friday from 9.00am to 5.00pm local time by contacting the Bureau's Climate Services sections in Queensland, NSW, SA, Victoria and Tasmania at the following numbers:
THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 26th November 2008