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BAMOS November 2025
Charts of the Past with Blair Trewin 7 February, 1997
Late January and early February featured an active and southward-extending monsoon trough. At the start of February, the trough extended across north-central Australia, with monsoon lows in the Pilbara and western Queensland. Over the following days, it extended further south into Western Australia, and then into northern South Australia from the 6th onwards, remaining slow-moving for several days. This was coupled with an equally slow-moving blocking high, which started as a ridge along the east coast on the 2nd, and then moved very slowly into the western Tasman Sea, only starting to move eastwards from the 8th.
The initial stages of the monsoon trough brought very heavy rain to western Queensland and to parts of Western Australia. There were widespread five-day falls exceeding 200 mm in western Queensland from 30 January to 3 February, including a record 313.2 mm at Tambo. This brought major flooding downstream in the Barcoo and Warrego rivers over the following days, with widespread inundation in Charleville( where the peak on the 4th was at the time the second-highest on record) and Blackall. Broome had its wettest day on record on 30 January with 476.6 mm, including 415.4 mm in five hours. As the system moved south, Mount Vernon, near Newman, received 408.6 mm in the first four days of February. There was substantial flooding in the Ashburton River.
From the 5th onwards, the focus of the heaviest rain shifted into South Australia, initially as severe thunderstorms on the 5th( with Cleve, on the Eyre Peninsula, receiving 77 mm in 75 minutes), and as more widespread rain over the next two days. The northerly flow was extremely humid, with dewpoints reaching 26.2 ° C at Marree and the mid-20s at several other interior South Australian sites.
Much of outback South Australia received at least 50 mm, with some areas recording well over 100 mm. The heaviest falls were in the far east of the state, west of Broken Hill, with the highest daily total being 174.1 mm at Manna Hill( Benda). In total, the site received 277.0 mm over two days and 326.0 mm over four, well in excess of the annual mean for the area. This led to severe flooding, closing the Barrier Highway for several days and causing major damage to the main railway line. The rains extended into the western border areas of New South Wales and far northwest Victoria, with 132.0 mm at Scotia Sanctuary, north of Lake Victoria. The most significant rain remained north of Adelaide, but the eastern suburbs experienced damaging squalls on the evening of the 6th.
East of the system, there was persistent heat and humidity, especially in Victoria. Melbourne reached 40.9 ° C on the 5th and 39.9 ° C on the 7th, and had a record four consecutive nights above 23 ° C from the 6th to the 9th, while other noteworthy high minimum temperatures included 29.3 ° C at Walpeup on the 6th and 28.6 ° C at Kerang on the 7th. Combined with another heatwave later in the month, this made February one of the hottest months on record for significant parts of southern Australia, including most of Victoria, coastal South Australia and southern inland New South Wales. Melbourne ' s mean minimum of 18.6 ° C and monthly mean( maximum and minimum combined) of 24.4 ° C are the highest on record for any month, and it is one of only five months with a mean maximum above 30 ° C. The statewide mean minimum was the highest on record for February for Victoria and South Australia and the equalhighest for New South Wales. The monthly mean temperature was the highest for Victoria.( Conversely, it was an unusually cool month in northern Australia, with temperatures during the month failing to exceed 40 ° C anywhere in the Northern Territory or Queensland except very close to the southern border). With humidity generally high and winds light, fire activity was modest despite the persistent heat.
Synoptic chart for 0000 UTC, 7 February 1997