Charts of the Past with Blair Trewin
BAMOS Sept 2017
32
Charts of the Past with Blair Trewin
23 June 1981
The winter of 1981 was a very wet winter in much of mainland southeastern Australia , especially in Victoria where it was the wettest winter on record . Repeated cutoff lows resulted in June , July and August all being substantially wetter than average . Although seasonal mean temperatures were close to the 1961-1990 average , the systems which occurred were still cold enough that most of the precipitation fell as snow on the higher parts of the Australian Alps ; 1981 went on to have the highest peak snow depths on record at Spencers Creek in the NSW Snowy Mountains .
1981 also saw one of the most significant low-level snowfalls in parts of southern Australia . The system responsible for this reached Australia as an active cold front which crossed the southwest of Western Australia on 20 June . The front crossed South Australia the next day , by which time a cutoff low had formed south of South Australia . The cutoff low moved slowly to be centred west of Tasmania on the 22nd and near the southwest coast of Victoria on the 23rd , where it stayed nearstationary for two days before weakening in situ and being reabsorbed into the westerlies by the 27th .
The most significant low-level snowfalls occurred as a result of a pool of cold air on the west side of the low . Initially this affected South Australia , with snow on the 21st at Wilpena and Blinman in the Flinders Ranges . The snow extended further south the next day , falling to around 400 metres in the Mid-North and affecting centres such as Clare , Jamestown and Hallett , as well as the higher parts of the Mount Lofty Ranges . A notably cold day during this period was 6.4 ° C on the 22nd at Kimba on Eyre Peninsula , nearly 2 ° C below its next coldest day on record .
On the 23rd the focus of the snow moved to western Victoria . In southwestern parts of the state it was described as the most significant snowfall since 1910 , with falls to near sea level in places . Donald and Terang received their first reported snowfalls on record , and St . Arnaud its first since 1901 , whilst there were also falls in Maryborough and Stawell . Snow also fell to low levels in northeast Victoria . The cold pool weakened the next day , although snow still fell on the 24th on the higher parts of the NSW Central and Southern Tablelands . Unsurprisingly , there were some very low maximum temperatures on the 23rd ; Mount Gambier ( 7.2 ° C ) and Warrnambool ( 7.0 ° C ) had their coldest days on record , whilst June records were set at Ballarat ( 4.2 ° C ), Hamilton ( 6.0 ° C ) and Ararat ( 5.0 ° C ), and Beechworth ( 2.4 ° C ) had its coldest June day since 1922 . The cold air largely bypassed Tasmania with no abnormal conditions reported there .
Rainfall totals with the system were generally light to moderate , although there were locally heavier falls ( near 50 mm ) in the Adelaide Hills and at Cape Nelson in southwest Victoria . Heavier rains occurred in northeast Victoria and the Adelaide Hills on the 25th , bringing significant flooding in the latter region . On the higher alpine peaks this fell as snow , with the snow depth at Spencers Creek increasing from 61 cm to 162 cm in a week .
In Western Australia , the main impact of the event was frost , with very low minimum temperatures in the southern inland on both the 22nd and 23rd . The most extreme conditions were in the Goldfields and Interior . Menzies ( −4.8 ° C ) had its coldest night on record , while June records were set at sites including Yeelirrie ( −5.0 ° C ), Kalgoorlie ( −3.0 ° C ) and Giles ( −1.6 ° C ).
Synoptic chart for 1000 AEST , 23 June 1981