|WA Seasonal Rainfall Outlook: probabilities for January to March 2007, issued 20th December 2006|
Neutral rainfall outlook for early 2007 in WA
Seasonal rainfall odds for the March quarter (January to March) do not strongly favour either wetter or drier than average conditions across Western Australia, the Bureau of Meteorology announced today. The pattern of seasonal rainfall odds across WA is a result of higher than average temperatures in the Pacific Ocean (because of El Niño) and the Indian Ocean.
The chances of exceeding the median rainfall for the January to March period, are between 40 and 55% across WA. So in years with ocean patterns like the current, about four or five or March quarters out of ten are expected to be wetter than average over the State, with about five or six out of ten being drier.
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 southwest of a line from Exmouth to Eucla, and in parts of far eastern WA. Elsewhere the effect is only weakly consistent (see background information).
The Southern Oscillation Index (SOI), negative for the seventh straight month as a result of the El Niño, rose from −15 in October to −1 in November. The approximate SOI for the 30 days ending 17th December was −4.
The current Pacific El Niño pattern, of which the low SOI is but one indicator, is expected to persist for most of the summer. For routine updates and comprehensive discussion on the latest data relating to El Niño, together with details on what the phenomenon is and how it has affected Australia in the past, please see the ENSO Wrap-Up.
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|More information on this outlook is available from 9.00am to 5.00pm (WST) Monday to Friday by contacting the Climate and Consultancy section in the Bureau's Perth Office: (08) 9263 2222.|
THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 23rd JANUARY 2007