“Ravaged by the harshest water restrictions in Australia, Goulburn, NSW, residents spent last night preparing for floods and possible evacuations.
“A huge downpour soaked the region yesterday, with Canberra receiving 44mm of rain.
“That has brought the total rainfall for the month to 83mm, but well above the June average of 38mm.
“At Goulburn, which has been struggling under Stage5 water restrictions, the Sooley Dam overflowed and the larger Pejar Dam rose to 21pc of capacity for the first time since 2002.
“But elation quickly turned to apprehension as emergency services went on a door-knock mission late last night to warn residents of a possible evacuation.
“Local farmer David Decorte … said, “We’ve gone from one extreme to another.”
Read the complete Farm Online article here: http://www.farmonline.com.au/news_daily.asp?ag_id=43403
And what else would you expect in Australia – a land of drought and flooding rains?
Jennifer Marohasy BSc PhD has worked in industry and government. She is currently researching a novel technique for long-range weather forecasting funded by the B. Macfie Family Foundation.
Is the recent flooding unusual? Yes – in that it does not happen every year.
The graph at the bottom of this BoM page shows the incidence of large flood events and the state of the SOI over the last 100 years.
http://www.bom.gov.au/lam/climate/levelthree/c20thc/flood.htm
As can be seen there is a correlation between a positive SOI (La Nina conditions) and widespread flooding.
The SOI measures the differential between sea level pressure in Darwin and Tahiti. If the pressure in Darwin is lower, the SOI is positive. This pressure differential affects the Trade Winds – which are moisture rich winds that blow from the Pacific towards Australia. If the SOI is positive, there are generally strong Trade Winds, if the SOI is negative, they are weak or non existent (i.e. the wind moves from an area of high pressure to one that is lower). And it is these warm moisture rich winds that when cooled bring rain to the East Coast.
Over the last month we have had a very positive SOI. The 30 day average is now over 10, and sustained high SOI values (near +10 or higher) are usually associated with wetter than average seasons over eastern and northern Australia, (even if La Niña thresholds are not reached).
http://www.bom.gov.au/climate/enso/
So, is the recent flooding unusual in the current conditions? Maybe not…
cheers
Arnost
Sigh..glib statements that Floods and Droughts exist, implying there is nothing to be gained from observing frequency.
Such statement exhibits a city siders view of Agriculture ..”we had some rain, so the drought is over..what are you whinging about”
I suggest you have a look at the Australian B. of Meteorology site, at the Rainfall distribution patterns over the last 25 years.