d. Australia

The rainy season over northern and northeastern Australia typically begins in October and ends in April. Much of the area receives more than 75% of the mean annual precipitation (with portions of extreme northern Australia recording more than 90%) during this seven-month period. For the 1994/95 wet season as a whole, precipitation totals averaged 200-500 mm above normal throughout north-central Australia (Fig. 61), and 200-400 mm below normal in the northeastern part of the country.

At Darwin the rainfall total of 2384 mm recorded during the 1994/95 wet season was the largest on record at this station dating to 1901 (Fig. 62). This total was 840 mm above the seasonal mean value of 1544 mm. Interestingly, 940 mm of precipitation, representing one-third of the total 1994/95 seasonal precipitation was recorded during January 1995. This value is the second largest monthly rainfall total recorded at Darwin in this century and is comparable to the record monthly rainfall total of 1014 mm observed in March 1977.

In the Northeast, the below-normal precipitation during the 1994/95 wet season (Fig. 61) contributed to severe precipitation deficiencies for the 13-month period ending in April 1995 (Fig. 63). Precipitation has been below normal in this region since the 1991/92 rainy season (Fig. 64 ), in association with the long-term ENSO conditions during the first half of the 1990s. However, a return to slightly above-normal precipitation during October and November of 1995 helped to ease this dryness. The change in the precipitation pattern over the Northeast accompanied the transition from warm-episode to cold-episode conditions in the tropical Pacific during the second half of the year (see section 3).

In the extratropics severe precipitation deficits also covered much of eastern and southern Australia for the 13-month period ending in April 1995 (Fig. 63). In the east-central region, these dry conditions began to ease during October-November 1995, with a return to slightly above-normal precipitation throughout the region. Wet conditions were particularly prominent in November, when large areas received abundant rainfall, with significant flooding in southern Queensland. Despite this late-year rainfall, precipitation totals for the period April 1991 to December 1995 were among the lowest on record over a large part of this region. In the southeast, significant precipitation deficits had abated by the end of July (Fig. 65), in response to above-normal precipitation during the May-July period (Fig. 66).

In Western Australia, Tropical Cyclone "Bobby" struck northwestern Australia near Onslow during February 1995, producing torrential rain (425 mm in 48 hours) and destructive winds. "Bobby" drifted southeast, generating widespread heavy rain and flooding across the interior of Western Australia - over 300 mm in areas that normally receive 225-275 mm throughout the entire year. This rainfall contributed substantially to the positive precipitation anomalies evident in the southwest during the October 1994-April 1995 period (Fig. 61 ).