Charts of the Past with Blair Trewin
BAMOS October 2021
29
13 November 1976
Following a generally wet and very cool October , including the lowest October mean maximum temperature on record for New South Wales , eastern Australia saw numerous severe thunderstorm outbreaks in November 1976 . The first of these came on the 2nd , which included a tornado at Snake Valley ( southwest of Ballarat ) and a famously wet Melbourne Cup .
The bulk of the month ' s thunderstorm activity came in the second week . A broad area of low pressure moved over the western half of Australia from the 7th before stalling over South Australia . A second low formed south of Western Australia on the 9th , and moved slowly southeast while deepening , absorbing the first low . These systems produced a moist northerly airstream over eastern Australia , which persisted until a trough crossed the region on the 14th . This also produced the first significant warm spell of the spring , with Melbourne reaching maxima between 29.6 ° C and 32.3 ° C on each day from the 10th to the 13th ( having not been above 26.1 ° C previously in the spring ), while further inland it reached 42.3 ° C at Marree ( SA ) and 40.0 ° C at Tibooburra ( NSW ).
The most significant severe thunderstorms occurred on the 12th and the 13th . On the 12th , a tornado tracked a length path north of Adelaide , extending from Elizabeth in the northern suburbs to Gumeracha in the Adelaide Hills , with significant damage along parts of its path . Large hail was reported in this storm , as well as at Balaklava further north .
The most destructive storm , however , was the next day , at Sandon , west of Castlemaine in Victoria . A tornado , rated as being of at least F2 intensity , tracked through the area . Two people were killed when a car was overturned by the winds , and numerous buildings in the area were destroyed or severely damaged . A less severe tornado was also reported in the Geelong area , and severe thunderstorms at Tamworth and Cobar in New South Wales . Large rainfall quantities were not generally a major feature of the storms in southern Australia , although there was a localised fall of 35.8 mm in 18 minutes in the Geelong suburb of Corio However , thunderstorms did bring heavy rain in southeast Queensland , with 119.6 mm at Greenbank and a number of other totals over 100 mm in suburban Brisbane . In addition to the localised damage from the most severe storms , hailstorms over the period resulted in widespread damage to fruit and grain crops , especially in New South Wales .
In marked contrast , the southerly airstream on the western side of the low produced a notable late-season cold outbreak in southern Western Australia . Perth ' s maximum of 15.9 ° C on the 12th was only 0.1 ° C short of its November record , while Albany Airport ' s 12.5 ° C was its third-lowest for November . There were light snowfalls on the Stirling and Poronogorup Ranges , one of only three known instances of November snow in Western Australia . Significant rain also occurred in the south-west of Western Australia , with daily falls of 40 to 50 mm in places in the 24 hours to 9am on the 12th .
Synoptic chart for 0000 UTC , 13 November 1976