Issued on 5 July 2011
Long-term dry conditions continue in southwest WA
Rainfall across much of southern Australia continued below average during June 2011. The largest areas of below average rainfall were in the southeast of the mainland, and in the southwest. Much of Tasmania, central and southern parts of the NT, southeastern WA and northeastern NSW experienced above average rainfall.
18-month rainfall deficiencies
For the 18-month period from January 2010 to June 2011, rainfall deficiencies remain in place through much of southwestern WA. Despite some rain at the end of the month, below average total rainfall during June 2011, over much of the southwest region, has extended and added to deficiencies. Areas of rainfall deficiency are very similar to those reported in the previous drought statement, with a large area of lowest on record rainfall covering much of the southwest corner, and severe deficiencies over most areas southwest of a Geraldton-Esperance line, except near the south coast from Albany eastwards. To relieve serious deficiencies in most areas in southwest WA, i.e. just to get out of the "serious deficiency" (lowest 10%) category, rainfall for the next three months will have to be in the "above average" to "very much above average" category.
After the very wet March, rainfall in southeastern Australia has been below average, and especially so in June. This continues a trend in recent decades of unusually dry mid-autumn to early-winter conditions to recur in most years (for example Victoria has experienced below average April-June rainfall in 10 of the last 11 years). This is a topic of active research, and climate scientists will be closely monitoring rainfall in this region.
Lowest on record - lowest in the historical analysis, which runs from 1900.
Severe deficiency - rainfalls in the lowest 5% of historical totals.
Serious deficiency - rainfalls in the lowest 10% of historical totals, but not in the lowest 5%.
Very much below average - rainfalls in the lowest 10% of historical totals.
Below average - rainfalls in the lowest 30% of historical totals, but not in the lowest 10%.
Average - rainfalls in the middle 40% of historical totals.
Above average - rainfalls in the highest 30% of historical totals, but not in the highest 10%.
Very much above average - rainfalls in the highest 10% of historical totals.
Product Code IDCKGD0AR0