Rainfall across the Ord region was generally close to average for the 2012–13 year (Figure C1). The total area-averaged rainfall over the Ord region during the 2012–13 year was 624 mm, which is slightly below the long-term area-averaged rainfall of 673 mm (based on the 1900–2013 period).
These conditions represent a decrease in rainfall compared to the 2011–12 year when rainfall was above average (see the 2012 Account). Consequently, flows in the major rivers within the region were much lower than the previous year (see Water overview).
Figure C1 Map of annual rainfall deciles for the Ord region during the 2012–13 year
Annual rainfall ranged from more than 800 mm in the coastal north of the region to less than 500 mm in the southeast of the region (Figure C2).
Figure C2 Map of total annual rainfall for the Ord region during the 2012–13 year
Generally below average rainfall was experienced across much of Australia during the 2012–13 year. There were no strong influences from large-scale climate drivers over the reporting period. Conditions in the Pacific Ocean were neutral and a negative Indian Ocean Dipole event developed at the end of the 2012–13 year.
The Ord region experienced above-average rainfall in the early part of the wet season (October–December); however, rainfall in the middle of the wet season (January–March) was well below the long-term average (Figure C3). The below average rainfall during this 3-month period contributed to well below average flows in the major rivers within the region (see Water overview), particularly during January–April when most flow usually occurs.
Figure C3 Graph of total monthly rainfall for the Ord region during the 2012–13 year compared with the long-term average and percentiles for the region
Evapotranspiration across the Ord region was generally above average for the 2012–13 year (Figure C4). The above average evapotranspiration reflects the climate conditions experienced across the region during the wet season months of November–March. As a result of above-average early wet season rainfall in November–December, more water would have been available for evaporation during the following months (January–March) when temperature was well above average (see Temperature).
Figure C4 Map of annual evapotranspiration deciles for the Ord region during the 2012–13 year
The total area-averaged evapotranspiration over the Ord region during the 2012–13 year was 641 mm compared to the long-term area-averaged evapotranspiration of 563 mm (based on the 1911–2012 period). Evapotranspiration was highest in the north along the coast and lowest along the southern part of the region (Figure C5).
Figure C5 Map of total annual evapotranspiration for the Ord region during the 2012–13 year
During the 2012–13 year, the Ord region experienced mean temperatures generally close to the long-term average (based on the 1911–2013 period); however, mean temperatures in the central parts of the region were above average (Figure C6).
Figure C6 Map of annual mean temperature deciles for the Ord region during the 2012–13 year
Mean temperatures across the Ord region ranged from more than 28 °C in the central and northwest parts of the region to less than 26 °C in isolated areas in the south (Figure C7).
Figure C7 Map of annual mean temperature for the Ord region during the 2012–13 year
Monthly mean temperatures for the Ord region were below the long-term average for several months in the first half of the reporting period and generally above average in the second half of the year (Figure C8). The above average temperatures during January–March are consistent with the effect of decreased cloud cover as a result of below average rainfall observed during this period. Mean temperatures in January and June 2013 were above the 90th percentile.
Figure C8 Graph of monthly mean daily temperature for the Ord region during the 2012–13 year compared with the long-term average and percentiles for the region