|National Seasonal Rainfall Outlook: probabilities for January to March 2008, issued 17th December 2007|
Mixed March quarter rainfall outlook
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 and southwestern Australia, while a drier season is favoured in some areas down the middle of the continent.
The pattern of seasonal rainfall odds across 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% in a large area extending from southeast Queensland across both the northern inland and east of NSW (see map). The southwest of WA also has similar chances, although it's a seasonally dry time of the year in this part of the country.
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 the country, while about three or four are drier.
In contrast, large parts of both the central NT and central SA have a 35 to 40% chance of exceeding the three-month median, meaning that these areas have a 60 to 65% chance of being drier than normal.
Over the rest of the country, 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 through eastern parts of NSW and Queensland, large parts of the NT and over much of southern and western WA. Elsewhere the effect is only weakly or 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.
|The following climate meteorologists in the National Climate Centre can be contacted about this outlook: Grant Beard on (03) 9669 4527, Lyn Bettio on (03) 9669 4165, Blair Trewin on (03) 9669 4623.|
Regional commentary is available from the Climate Services Sections in the Bureau's Regional Offices:
THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 24th January 2008