Exceptional Rainfall Dave McRae, Qld Climate Change Centre of Excellence, 09/03/10.
The Bureau of Meteorology has recently released a special climate statement that reviews the exceptional rainfall and flooding event experienced throughout southern and central Queensland during late February and early March.
The event began on 22nd February, when a strong low pressure system developed over the Northern Territory within the existing monsoon trough. Over the following week the monsoon low tracked south, triggering heavy falls through central and southern NT. The monsoon low then moved eastwards into southwest Queensland, leading to widespread heavy rain, first to southwest Queensland then spreading into the southern Queensland. Moist easterly flow, combined with a second low which formed off the coast near Fraser Island, also brought rain to coastal regions of southeast Queensland and northeast New South Wales.
The most remarkable aspect of this event was the area covered by the heavy rainfall and the total volume of rainfall that fell. A number of locations recorded new extreme daily rainfall totals including Bedourie (188 mm), Birdsville (168 mm), Glengyle (163 mm), Surat (154 mm), Glenmorgan (159 mm) and South Comongin (158 mm).
While El Niño events are typically associated with drier than normal conditions throughout eastern Australia, it is not unusual for major rainfall events to occur during the breakdown of an El Niño event. Examples including those of January 2007, January 1995, March 1983 and February 1973. For more information go to www.bom.gov.au/climate/current/special-statements.shtml
In the mean time based on a "Consistently Negative" SOI phase at the end of February there remains a 30 to 50% of getting above median rainfall throughout the northern half of Queensland for March through to the end of May. Generally throughout the southern half of the state there is a 40 to 60% chance of getting above median rainfall for March through to the end of May.
Extending into NSW and Victoria the chance of getting above median rainfall during March to May has improved to a 50 to 70% with the main exception being the north east of NSW.
As the autumn predictability gap approaches it will be interesting to see what direction the SOI takes. At this a time of year consistently negative values are not a major concern. However if the SOI does not return to more positive values during autumn it would be a warning sign for a likely dry winter/spring.
As of the 9th March the 30 day average of the SOI is minus 10.0. Daily updates on the SOI are available at www.longpaddock.qld.gov.au or to receive the latest SOI values sent to your mobile phone call (07) 4688 1459 or e-mail firstname.lastname@example.org