BAMOS Dec 2024
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Charts of the Past with Blair Trewin 26 January , 1998
One of the strongest El Niño events on record occurred in 1997−98 , but the conditions over much of Australia were not typical of El Niño . Significant drought was largely confined to Victoria , Tasmania and parts of southern New South Wales , and the tropical wet season was an active one . By mid- January , there had already been one extreme rain event in the tropics resulting from the remnants of a tropical cyclone , when moisture associated with ex-Cyclone Sid gave Townsville its wettest day on record ( 548.8 mm ) on 11 January , with significant flash flooding .
Following this was the formation of Cyclone Les in the Gulf of Carpentaria early on 24 January during a strong monsoonal surge . Les reached category 2 intensity in the Gulf and made landfall on its western shore near Numbulwar on 25 January , with heavy rain and local wind damage , but it was what happened after it weakened below cyclone intensity that produced its most significant impacts .
Very heavy rain fell near its track from east to west across the southern Top End . The heaviest falls were in the Katherine area , with widespread two-day totals of 300−400 mm for 26−27 January , locally reaching close to 500 mm . Katherine itself received 380.6 mm over two days , its second-highest on record ( after an event in December 1897 ), with 220.8 mm on the 26th . The highest daily total in the region was 337.0 mm at Jindare , southwest of Pine Creek on the 26th . While the rainfall totals were not unprecedented ( and the daily totals were exceeded in a December 2003 event ), the heavy rainfall was much more widespread than in the 1897 or 2003 events , and came on top of a wet start to the month , with January 1998 going on to be Katherine ' s wettest month on record .
Exceptional flooding resulted in the Katherine-Daly catchment . The Katherine River at the town bridge reached a height of 20.4 m , 1.1 m above previous record heights observed in 1957 ( and , with more uncertainty , in 1897 ). This inundated the main street to depths of up to 2 metres , as well as many remaining areas of the town . About 5000 people , roughly half the town ' s population , were evacuated . Record flood heights were also observed in the Daly River as the floodwaters moved downstream over the following week , affecting the Daly River community and several other settlements . Transport and communication links were badly affected , and total losses were estimated at $ 70 million ( in 1998 dollars ).
The system went on to become a cyclone again after moving out to sea , and tracked near the Kimberley coast with further flooding before dissipating near Broome on 1 February . A second cyclone , Tiffany , formed west of Broome on 25 January and reached category 4 intensity north of Port Hedland on the 27th , but did not make landfall .
Elsewhere , a trough stalled over eastern Australia from the 23rd , with a low forming at its southern end over eastern Bass Strait on the 25th . This low intensified over the following 24 hours with minimal movement , before moving to the southeast . There was widespread thunderstorm activity over Victoria and New South Wales on the 24th and 25th . A total of 87 mm of rain fell in a storm at Flemington , and flash flooding occurred in various parts of Melbourne ( with 3 cm hail also reported ), while in New South Wales 100 mm was reported in an hour at Gloucester on the 24th . As the low intensified , heavy rain became focused on Bass Strait . Flinders Island Airport received 107 mm on the 26th , its second-wettest day on record , while 145.4 mm fell in two days at Wilsons Promontory . East of the trough it was hot and humid , particularly in southeast Queensland , where on the 26th , Brisbane Airport had its hottest night on record ( 26.1 ° C ) and Amberley reached 40.1 ° C . The southwest of Western Australia was also hot , with 39.8 ° C at Perth and numerous sites reaching over 40 ° C .
Synoptic chart for 0000 UTC , 26 January 1998