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For the 7 and 24-month periods ending 30th April 2008
Long and short-term rainfall deficiencies persist
LINKS:
rainfall deficiencies definition
7-month rainfall deficiencies
24-month rainfall deficiencies
Short-term rainfall deficiencies expanded and intensified in central Australia as
a result of below average April rainfall. In addition, long-term rainfall deficiencies
at the two-year timescale have increased in most areas, except for southwest WA
which showed some easing of deficiencies.
See April
rainfall pattern
For the 7-month period from October 2007 to April 2008,
an area of serious to severe rainfall deficiencies covered much of the
southern half the Northern Territory and some adjacent areas in far western
Queensland. An area of lowest on record to the east of Alice Springs has
slightly increased. There were also some smaller patches of serious to
severe deficiencies near Marree in South Australia.
Rainfall deficiencies for the 24-month period from May 2006
to April 2008 are evident in southwest WA, Tasmania, southeast Queensland,
northern SA and in a band stretching from the Bight coast of SA across much
of Victoria and the western slopes and plains of southern NSW. The pattern
is very similar to that observed at the end of March, but as April 2008 was
drier than April 2006 in most areas, there was a slight increase of these
two-year deficits. One exception was southwest WA which had a wetter April
this year so the 24-month deficits eased somewhat. Record-low falls remain
evident on the Eyre Peninsula in SA and in southwest WA where they are smaller
in area. Compared with a month ago, record low falls at this time-scale
expanded near Melbourne and in eastern and northern Tasmania.
The worst of the long-term deficiencies are likely to remain for some time.
For example, above to very much above average rainfall (deciles 8-10) is
needed in the rainfall deficient areas over the next six months just to
elevate totals since May 2006 out of the lowest decile. Furthermore, due
to the seasonally dry period in northern parts of Australia, short-term
rainfall deficits in the NT are also likely to remain over the coming months.
The deficiencies discussed above have occurred against a backdrop of decade-long rainfall
deficits and record high temperatures that have severely stressed water supplies in the
east and southwest of the country. Several years of above average rainfall are required
to remove the very long-term deficits. The combination of record heat and widespread
drought during the past five to ten years over large parts of southern and eastern
Australia is without historical precedent and is, at least partly, a result of climate
change.
For more information go to a
Special Climate
Statement on the six years of widespread drought in southern and eastern
Australia, November 2001 to October 2007
Rainfall
deficiency maps for standard periods out to three years are
available.
Note: The terms used to describe rainfall in these
Drought Statements have the following meanings -
Serious deficiency
- rainfalls in the lowest 10% of historical totals,
but not in the lowest 5%
Severe deficiency
- rainfalls in the lowest 5% of historical totals
Lowest on record
- lowest since at least 1900 when the data analysed begin
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
For more information regarding this rainfall
deficiencies statement, please contact the following
climate meteorologists in the National Climate Centre:
Grant Beard on (03) 9669 4527
Blair Trewin on (03) 9669 4623
Lyn Bettio on (03) 9669 4165
External Sites Relating to Drought
The Bureau of Meteorology does not make formal drought declarations
as these are done by either the relevant State Governments or by the
Australian Government. The Australian Government Program is called
Exceptional Circumstances
and it is administered by the Federal Department of Agriculture,
Fisheries and Forestry (DAFF). General information about Australian
Government drought assistance is available at
http://www.daff.gov.au/droughtassist.
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