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 SE AUS: Late winter warm wave gives TAS its hottest-ever August night
The strong northwesterly airstream shown on the surface charts above produced an exceptionally warm August night across a broad slice of SE AUS. Minima this morning were up to 15.7C above normal in SA, while in TAS both the State and Hobart City records fell by large margins. The only sub-zero minimum in the country was -0.4 at Glen Innes. High overnight temperatures followed an exceptionally warm day yesterday, when at least seven locations in TAS set new August maximum temperature records. Fresh to strong winds and a blanket of cloud during the night helped reduce the normal overnight cooling.
The warmest August 24-hour minimum temperature on record for TAS is 15.0C, set at Strahan on 26 August 1977 and equalled by Swansea on 28 August 1994. This morning, Grove Research Station, 23km WSW of Hobart in the Huon Valley, recorded a low of only 16.1 in the 24 hours to 9am, 1.1 above the state record and 1.9 above its own previous August record in 45 years of observations. The norm for August at Grove is 2.6. Hobart City, with records dating back to 1882, recorded 15.0, 8.1 above normal and 0.6 above the previous record set on 19 August 1885. The figure of 15.0, however, was the reading at 9am yesterday morning when the minimum temperature thermometer was reset for the next official 24-hour period. Overnight, the lowest Hobart temperature was 16.2 just after 6 this morning.
On the mainland, minimum temperatures relative to average were warmest in SA, western NSW, NW VIC and southern NT. Marree's low of 21.9 was 15.7 above average followed by a 14.8 above average reading of 19.2 at nearby Arkaroola. Broken Hill recorded a low of 20.1 (+14.4), Mildura 18.8 (+13.5) and Alice Springs 18.0 (+12.0). Maximum temperatures in the same area today were more restrained but still 8 to 11 above the seasonal norm.
In VIC, some long-standing records for high August minima fell by enormous margins:
- Benalla 13.8 (previous record 12.8 in 102 years of record)
- Ouyen 16.8 (14.7, 69)
- Mildura Airport 18.8 (15.6, 60)
- Wonthaggi 14.5 (14.0, 37)
- Noojee 13.0 (12.7, 22)
At Loxton SA, an unusually large and early flight of moths was reported in the warm conditions overnight.
SE AUS: Storm to hurricane force winds cause damage and disruption
A strong northwesterly airstream and a particularly ferocious cold front caused damage and disruption in SA and VIC and record high winds in the Alps today. The Automatic Weather Station on the summit of Mt Hotham in VIC recorded a wind gust of 198km/h just before midnight which, if confirmed, will be the highest wind gust ever recorded in the state. Both Adelaide, Melbourne and some country areas experienced damaging winds.
Gale force northwesterly winds preceded an especially vicious cold front that swept into Adelaide early this evening. As the surface charts above show, the front was attached to a deep secondary depression just a few hundred kilometres off the SA coast. With a central pressure of around 983hPa, the low set up a strong pressure gradient across southern parts of the state and the Great Australian Bight. The front also separated temperatures up to 10 above average from much cooler southern air, providing additional turbulence across the frontal zone. As the front moved east along the SA coast, it brought wind gusts of 95km/h at Ceduna, 104 at Coles Point, 113 at Port Lincoln and 124 at Cape Willoughby on Kangaroo Island. The southwesterly stream following the front was almost as boisterous with Neptune Island gusting to 111km/h both with the passage of the front and around 11pm, long after its passage. In and around Adelaide the strongest gusts measured during the late afternoon and evening were 104km/h at Kadina and Mount Lofty, 102 on Hindmarsh Island, 100 at Minlaton, Outer Harbour and Mount Crawford, and 95 at Adelaide Airport. More details are in Highest gusts and High AWS wind reports below.
The main impact of the winds and scattered lightning strikes was on the state's electricity supply. Around 30,000 properties across 70 Adelaide suburbs lost power as 75 powerlines were damaged or brought down by the wind or falling trees and branches in the city. A further 25 lines came down in country SA. Spokesman Craig Cock of electricity distributor ETSA estimated damage would top $1.5m. He told ABC Radio "The number of power lines out at any one stage in the history of ETSA utilities - this far exceeds it". Blacked out traffic lights caused traffic snarls while the Kangaroo Island ferries had to be cancelled due to attrocious conditions in Backstairs Passage. Minor to moderate damage was widespread across Adelaide, with trees and branches blown onto roads, windows shattered and loose roofing blown from buildings. At one point, the SES fielded 170 calls for help in just 9 minutes. The most serious reports of damage, however, were a 10m tree blown onto a house in Seacliff Park and a car crushed by a falling tree in St Peters. High seas and gales in the Great Australian Bight, resulted in two people on a 12m motor yacht sending out a mayday call early evening and the co-ordination of a rescue effort.
The front raised widespread dust in western SA and on the Eyre Peninsula, with visibility less than a kilometre at Woomera at 3pm. Raised dust was also reported from western NSW, NW VIC and SW QLD.
In VIC, gale force northwesterlies during the day gusted over storm force (90km/h) across much of the state while two bands of heavy rain crossed the state, the second bringing widespread storms during the evening. Exposed mountain and coastal locations reported some impressive wind gusts, with the 198km/h gust recorded on the summit of Mt Hotham at 11.58pm a new VIC record if verified. Shortly before, the mountain recorded a 10-minute average wind of 133km/h to 11.45pm, and recorded gusts over 100km/h at most observations during the day. Other strong Alpine and coastal wind gusts included Mt Buller 122km/h, Falls Creek 133, and Fawkner Beacon in Port Phillip 122. Over the border in NSW, Thredbo reported a gust of 133km/h mid-afternoon. Equally impressive were gusts recorded in more sheltered locations: Kilmore Gap and Eildon Fire Tower 109km/h, Dunns Hill (Mt Dandenong) 107, Mortlake 106, and Melbourne Airport 102. (More here and here.) Heavy rain in the state's northeast saw flood warnings issued for most northeastern and northern rivers, with Goulburn River tributaries Acheron and Seven Creeks topping minor flood levels during the evening.
Damage from strong winds in Melbourne resulted in over 750 callouts for the SES in the 24 hours to 10.30pm, most of them related to trees or branches blown onto houses and roads or minor roof damage. At Belgrave, a gum tree fell through two storeys of a home. Around 5.40am a tree was blown onto Mt Waverley station and overhead powerlines, stopping services between Darling and Glen Waverley for two hours, while another tree blown onto the Alamein Line east of Camberwell cut services between Willison and Alamein.
Newsbits
TAS: Rain brings joy to farmers but grief to skiers: The warm northwesterly airstream across TAS, picking up moisture on its passage across Bass Strait, brought good rain to central northern TAS today. In the 24 hours to 9am, Erriba (south of Devonport) recorded 30.2mm and Quamby Bluff (near Deloraine) 28.8 with general falls of 15 to 25mm in the area. Rain continued today, with some heavy falls this evening as a trough crossed the state. The Meander River at Meander topped minor flood level during the evening and most northern streams were rising strongly. While August rain has been good, year-to-date rainfall across the north is still well below average and a good inflow to dams is urgently needed. The rain and warm conditions, however, spelt an end to Ben Lomond's brief skiing "season", with all snow washed away by today.
QLD: Thick fog in Toowoomba: Fog reduced visibility to 20m in Toowoomba this morning following light overnight rain.
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