|NSW Seasonal Rainfall Outlook: probabilities for May to July 2006, issued 21st April 2006|
50:50 chances for above average seasonal rainfall
The current seasonal rainfall odds do not strongly favour either wetter or drier than average conditions. Therefore, the chances of accumulating at least median rain during the late autumn to mid-winter period (May-July) are close to 50% across New South Wales, the Bureau of Meteorology announced today.
The outlooks are based on relationships between Pacific and Indian Ocean temperatures and Australian rainfall. Recent ocean temperatures have not been sufficiently warmer or cooler than average to produce a strong bias in rainfall outlook odds.
For the May to July period, the chances of above median rainfall are mainly between 50 and 55% in western NSW, and between 55 and 60% in the east of the State (see map).
So in years with ocean patterns like the current, about five or six May to July periods out of ten are expected to be wetter than the median over the State, with about four or five out of ten being drier.
Outlook confidence is related to how consistently the Pacific and Indian Oceans affect Australian rainfall. During the May-July period, history shows this effect to be moderately consistent in patches over the northeast half of the State, but excluding the Moree region where the effect is only weakly consistent (see background information).
The Southern Oscillation Index (SOI) has continued to fluctuate with a value of +14 in March following the reading of zero in February. The approximate SOI for the 30 days ending 17th April was +19. For more information on the SOI and the current status of ENSO, 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 from 9.00am to 5.00pm (EST) Monday to Friday by contacting the NSW Climate Services section in the Bureau's Sydney Office: (02) 9296 1610 or (02) 9296 1525.|
THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 25th MAY 2006