Charts of the Past with Blair Trewin
Charts of the Past with Blair Trewin
BAMOS March 2017
27
14 August 1934
Late winter is a time when active weather systems regularly cross southern Australia , bringing strong winds and rain to the southeast , and dry windy conditions further north . Such systems were a more frequent occurrence in the first half of the 20th century than they are now , and August 1934 brought a particularly noteworthy example .
An intense low pressure system was positioned south of South Australia on the 13th . Whilst a lack of data from over the oceans makes it hard to determine with confidence the system ’ s exact configuration , the low , combined with strong ridging over and south of southwestern Western Australia , brought southwesterly flow with a long fetch into South Australia . This flow remained in place through the night of the 13th and into the 14th ; by evening , a closed low was centred southwest of Mount Gambier , before moving quickly eastwards to be east of Bass Strait by the morning of the 15th . It was a notably intense low ; the pressure at Adelaide reached 986 hPa at 1.30 p . m . on the 14th , the lowest on record there at the time ( subsequently surpassed in 1981 and 2016 ), whilst Sydney set an August record ( at the time ) of 992 hPa that evening .
The direction of the wind was ideal for a substantial storm surge to enter Spencers Gulf , and this transpired on the evening of the 13th , with major coastal flooding along its northern shores . Hardest-hit was Port Pirie , where much of the town was inundated ( there are conflicting reports as to whether the collapse of an embankment contributed to this ), with some parts of the town still under water three days later . Two deaths were reported ( a rare instance of casualties in Australia from storm surge outside of tropical cyclones ), and more than 300 families were left homeless . There was also significant flooding at Port Germein , where water depths of two feet were reported at the Post Office , and at Port Augusta .
High winds were also reported on land , with estimated gusts of 110 to 130 km h -1 over the Eyre Peninsula , causing widespread although mostly minor wind damage there , and in the Riverland and Mid-North . The strong winds also extended to the eastern outback with duststorms reported in western New South Wales and western Queensland .
Rainfall was widespread through southeastern Australia ( including the southern outback , and the southern half of New South Wales ). As is typical for systems of this type , general falls were modest ( typically 5 to 20 mm over flat terrain over the three days 14 – 16 August ), but were strongly amplified over and upstream of topography . The heaviest falls were in and near the Alps , and the Adelaide Hills and southern Flinders Ranges . In South Australia , 101.6 mm fell at Stirling over the two days 14 – 15 August , and 61.7 mm at Lobethal on the 15th , whilst further north 55.9 mm fell that day at Melrose . In the eastern states , noteworthy daily falls included 86.4 mm at Walwa and 72.1 mm at Hotel Kosciusko on the 15th , and 67.1 mm at Batlow on the 14th . Whilst temperatures were below normal , it was not a particularly cold system compared with some of its type ; the coldest day was the 15th , with 13.2 ° C at Adelaide , 11.1 ° C at Melbourne and 8.6 ° C at Hobart .
This system also marked a transition from dry to wet conditions . The seven months from January to July 1934 had been very dry in many parts of the southeast , particularly in the agricultural areas of South Australia where seven-month rainfall totals were in the lowest decile . The August rains set the scene for four months of rainfall in the highest decile over most of the same regions . Whilst this was very beneficial for agriculture , it set the scene for disastrous floods in southern Victoria , including Melbourne , at the end of November .
Synoptic chart for 0900 AEST , 14 August 1934 .