Northern Australia (indicated by the boxed area in Fig. 65a) experiences a tropical climate with a well-defined rainy season that typically begins during October and ends in April. Much of the area receives more than 75% of its mean annual rainfall during this 7-month period, with portions of extreme northern Australia recording more than 90%. The annual cycle is strongly modulated by ENSO, with below- (above-) normal rainfall typically observed during Pacific warm (cold) episodes (Ropelewski and Halpert 1987, 1989). The 1996/97 wet season featured above-normal rainfall in the central and northwestern areas, which extended into the normally arid inland areas of western Australia. At Darwin, the seasonal rainfall total was 2374 mm, just 8 mm below the record high total observed during the 1994/95 season (Halpert et al., 1996).
For the region as a whole, area-mean rainfall was near-normal to above-normal during the peak months (DJF) of the wet season (Fig. 65b ), in association with continued weak cold episode conditions into early 1997. During this three-month period, rainfall totals were among the highest on record over extensive areas of central and northwestern Australia, with many places having their wettest season on record. The 1996/97 wet season also featured an abrupt end to the rains in late-March, in association with the development of warm episode conditions in the tropical Pacific.
Elsewhere during the year, rainfall was below-normal in southeastern Australia from March-November, with the largest deficits observed across southern Victoria and portions of eastern New South Wales (Fig. 66). In southern Victoria, dry conditions persisted from October 1996 through the end of the year. Within this region, Melbourne recorded its second driest January-November period in the 140-yr record, with accumulated rainfall reaching only 355 mm (59% of normal). Despite these dry conditions, the region experienced good rainfall during September and November, which occurred during a critical period in the growing cycle and in some cases turned imminent crop failure into good yields. These overall dry conditions during 1997 contrast with the previous year, when Melbourne recorded its second wettest January-September on record.
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