BAMOS Vol 33 No.3 September 2020 | Page 19

Charts of the Past with Blair Trewin

Charts of the Past with Blair Trewin

BAMOS Sep 2020
19

30 June 1922

One of the most significant cold outbreaks observed in southeastern Australia occurred at the end of June 1922 . A low developed near Tasmania on the 28th , and remained near‐stationary until the 30th as a ridge strengthened over Western Australia , placing southeastern Australia in a strong southwesterly airstream . Conditions gradually moderated from 1 July as the low moved to the east .
It became progressively colder over the south‐east from the 27th onwards . Separately , the 28th was a cold day in central Australia as a cloudband developed over the region , with a maximum of 8.9 ° C at Alice Springs . The cold outbreak in the south‐east began in earnest on the 29th . Initially it was at its most significant in South Australia . Snow fell over the Adelaide Hills and the Mid‐North , as far north as Clare and Jamestown , at elevations down to around 400 metres . Adelaide had its coldest day on record , with a maximum of 8.3 ° C . Very cold air had also reached western Victoria by then ; Ballarat ’ s maximum of 2.5 ° C was also its coldest on record , and Warrnambool and Cape Otway only reached 7.2 ° C . Heavy rain fell on exposed parts of the southern Victorian coast , with 63 mm at Wilsons Promontory and 47 mm at Johanna , although elsewhere falls were mostly light .
The coldest air of the event crossed Victoria and southern New South Wales overnight on the 29th and into the 30th , with very cold temperatures and snow to low levels . The most abnormal falls were in northeast Victoria and adjacent areas of southern New South Wales . In these areas snow fell to plains level . Albury‐Wodonga had its most significant snowfall on record , Howlong reported snow for the first time , and light falls were also reported at locations including Rutherglen , Benalla , Euroa and Dookie , with 15 cm falling at Beechworth . Although the coldest air did not reach that far north , it was still cold enough for snow above 700 metres in the Bathurst area .
There were also very significant falls around Melbourne . Heavy snow fell throughout the Dandenong Ranges , with over 30 cm at Gembrook and Cockatoo , 20 cm at Olinda , and 10 to 15 cm at Belgrave and Emerald . The snow fell to near 100 metres in areas east and southeast of Melbourne , including Ringwood , Warburton , Upper Ferntree Gully , Healesville and Warragul . Melbourne ’ s maximum was 8.1 ° C for the second successive day , one of only two occasions when it has been so cold on consecutive days . No mainland Victorian station reached 10 ° C ( it was 10.0 ° C at Gabo Island ), and the average maximum over the state was 6.83 ° C , the lowest on record , with notable values including 5.0 ° C at Bendigo , 6.1 ° C at Swan Hill and 4.4 ° C at Echuca . The coldest air passed west of Tasmania , although that state still received widespread highland snow .
The central Australian cloudband also extended east on the 29th and 30th , with widespread two‐day rainfall totals of 20 to 50 mm over much of southern inland Queensland . 41 mm fell at Surat on the 29th , and 45 mm at Glenmore , in the Darling Downs , on the 30th . South Australia ’ s heaviest rain of the event also occurred on the 30th as a small secondary low developed over the state ’ s southeast , with falls near 30 mm in the Upper Southeast ; on the north side of the low , strong winds caused widespread tree and building damage in parts of Adelaide .
Conditions warmed in the southeast from 1 July onwards , although the 1st was a cold night in much of northern and eastern New South Wales , with minima of −7.2 ° C at Inverell and 3.8 ° C at Sydney . By then cold air had become established through much of tropical Australia . Darwin had maximum temperatures of 24.2 ° C and 23.8 ° C on the 1st and 2nd , whilst Broome went on to have an equal‐record 11 consecutive days below 25 ° C from 29 June to 9 July . Although Victoria and Tasmania went on to have a relatively mild month , the extensive below‐average temperatures in tropical and central Australia made July 1922 Australia ’ s second‐coldest on record , after 1929 .
Synoptic chart for 30 June 1922 ( time of day unknown )