|Southeastern Aust Seasonal Rainfall Outlook: probabilities for January to March 2008, issued 17th December 2007|
Mixed March quarter rainfall outlook for SE Australia
For southeastern Australia the national outlook for total March quarter rainfall (January to March), shows mixed odds for exceeding the seasonal median. There are moderate to strong shifts favouring above average totals in parts of eastern NSW, while a drier season is favoured in parts of South Australia.
The pattern of seasonal rainfall odds across southeastern Australia is a result of cooling across the equatorial Pacific in association with La Niña, and continuing higher than average temperatures in the central to southeastern Indian Ocean.
The chances of exceeding the median rainfall over January to March are between 60 and 75% across both the northern inland and east of NSW (see map). So for every ten years with ocean patterns like the current, about six or seven March quarters are expected to be wetter than average in these parts of southeastern Australia, while about three or four are drier.
In contrast, a large part of central to eastern SA has a 35 to 40% chance of exceeding the three-month median, meaning that this area has a 60 to 65% chance of being drier than normal.
Over the rest of southeastern Australia, the chances of exceeding the three-month median rainfall are between 40 and 60%.
Outlook confidence is related to how consistently the Pacific and Indian Oceans affect Australian rainfall. During the March quarter, history shows the effect to be moderately consistent in much of eastern to northern NSW and in small patches in western Tasmania, southwest Victoria and western SA. Elsewhere the effect is largely only very weakly consistent (see background information).
A La Niña event is in progress across the Pacific Basin and computer models indicate it will persist at least until the early part of 2008. The 30-day value of the Southern Oscillation Index (SOI) was +8 as at 12th December. 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 24th January 2008