SE AUS: Storms, gales and record rain
Strong temperature differences fuelled an active cold front as it swept across SA, NSW, VIC and TAS today. Storms with the front and a broad rainband that moved across VIC, TAS and southern NSW ahead of it produced widespread totals ranging from 10 to over 80mm. Severe thunderstorms caused flash flooding, power and transport disruption and some damage in VIC and southern NSW, and minor or moderate river flooding in NE VIC.
An active cold front crossed the SE SA coast mid morning and lay from Melbourne to NW NSW by late evening. Temperatures ahead of the front were well above normal for September, with readings at 850hPa (about 1.4km up) of 16 to 20C across much of NSW. Behind the front, 850hPa temperatures dropped to below zero over Adelaide during the evening, with the 1000/500hPa thickness analysed at a very low 5340m over Kangaroo Island at 10pm. These strong temperature differences, helped by a jet stream across southern NSW with a core speed of 250km/h, created a zone of strong uplift that intensified as it moved east across VIC during the day.
A band of moisture feeding in from the Kimberley preceded the front. A significant rain band developed in SE SA early morning, moved to an area from the NW TAS coast through Melbourne to the NSW Riverina by mid afternoon and onwards to eastern VIC and SE NSW by late evening. Thunderstorms accompanied the northern extension of this rain area in SA and across southern NSW and northern VIC throughout the day.
As the front pushed into the warm, humid air across central VIC late afternoon, a second line of storms developed from the Otways to around Ballarat early evening. This storm line moved east while extending southwards to northern TAS and northwards into southern NSW, finally passing out into the Tasman early Thursday morning.
|Rainfall readings for the 24 hours to 9am Thursday cover the event.
The rainband and following frontal thunderstorm line gave widespread rainfalls above 10mm, as the maps at left show. The heaviest totals were in southern inland NSW, NE VIC and northern TAS where orographic uplift over mountains enhanced an already unstable situation. The heaviest totals, from Albury east into the upper Murray Valley, also benefited from torrential falls associated with one thunderstorm complex early evening. Rainfall totals over 50mm are listed in tomorrow's wettest column, and high short-duration falls are listed in downpours below.
NE VIC, southern NSW
The main rainband arrived around Albury mid-afternoon. However between 6 and 7pm a severe thunderstorm developed to the NW of the city and propagated east and SE, bringing a line of torrential rain across the city. 29mm fell at Albury Airport between 7 and 8pm, giving the city a 6-hour total of 50mm from 3pm to 9pm and a September record 57.0mm for the 24 hours to 9am Thursday. Nearby Hume Reservoir's 53.8mm for the 24 hours was its highest September reading in 84 years.
The settlement of Jindera, 10km NW of Albury, was isolated by flash flooding, and SES had to use special high-clearance vehicles to reach the town to sandbag properties. Many roads in the area were flooded, including the main Albury to Urana and Albury to Wagga Wagga roads, and damage was caused to track on the Sydney to Melbourne main railway at Table Top and Gerogery, forcing the busing of passengers from two trains between Wagga and Melbourne. Albury SES attended over 50 calls. Water entered homes at Lavington, and downed trees blocked roads and brought down powerlines in North Albury.
As the storm moved into the upper Murray Valley, Snowy Mountains and Victorian Alps, even higher totals were reported. Between 6pm and 3am Thursday, Hunters Hill AWS (55km E of Albury) registered 58mm, Berringama (10km farther east) 69mm, and Biggara (15km SE of Corryong) 55mm. Corryong's 24-hour total to 9am Thursday of 76.0mm substantially eclipsed the previous record of 57.2mm in 112 years of rainfall readings. Thredbo Top Station recorded 84mm between 6pm and 6am Thursday, the rain only turning to snow in the last hour as cold air behind the front moved in.
Moderate flooding was reported in the upper Murray River, with discharge from Khancoban Dam peaking at 325 cubic metres/second about 8am Thursday. The river peaked at both Biggara and Bringenbrong around midday Thursday at levels at or just above moderate flood stage (peaks of 2.6m and 3.43m respectively). Flooding in the Mitta Mitta River above Dartmouth Dam was just below minor level. In the upper reaches of the Kiewa River, levels reached close to minor flooding, while the peak downstream at Bandiana of 2.83m at 8am Thursday was just above the minor flood stage.
Elsewhere in VIC
Elsewhere in VIC, the greatest impact was felt from the second line of storms that developed along the cold front. These moved through Ballarat around 7pm and Melbourne around 9pm, then into Gippsland where they slowly lost intensity. Several bands of torrential rain embedded in the storm complex brought widespread flash flooding, while strong winds and lightning strikes caused damage. The highest reported wind gust was 107km/h at East Sale around 11pm. Flash flooding, flooding of house roofs and roads, and damage from wind-borne debris were widespread in Ballarat and parts of Melbourne, with the SES responding to 200 calls in Melbourne, mostly from northern suburbs. The Alpine Hotel in Bright lost part of its roof around 12.30am Thursday, and there were unconfirmed reports of extensive damage to a house roof in East Brunswick in inner northern Melbourne. In Myrtleford, 50km SSW of Wodonga, half the roof and a verandah were blown off a house, a 70-year-old oak tree was ripped out of the ground, and hundreds of trees were described as having their "tops shredded" along a 50m wide corridor from wind that struck around midnight. A resident of Upper Sandy Creek, 40km SE of Wodonga, was lucky when a ring of 30m-high gum trees surrounding his home were blown down like dominos, leaving the house unscathed. Lightning strikes caused power loss to thousands of homes in and around Ballarat and in Melbourne's north and east, as well as damage to signalling equipment on the Sydenham Line in Melbourne that forced buses to replace trains during the evening. Horsham and Edenhope in the state's west lost power for an hour when lightning struck a feeder line at 5.27pm.
Earlier in the day, squally winds ahead of the front produced some high inland wind gusts including 113km/h at Mt Hotham, 100km/h at Dunns Hill near Mt Dandenong, 96km/h at Kilmore Gap (50km N of Melbourne) and 93 at Melbourne Airport.
Southern NSW and the ACT
Rain, including short bursts of heavy rain and some thunderstorms, moved through the eastern Riverina and Southern and Central Slopes and Tablelands during the evening and into the early hours of Thursday morning. In addition to the heavy falls already mentioned in the NSW/VIC border areas, very heavy rain fell in an area from north of Goulburn to north of Cowra. For the 24 hours to 9am Thursday, Taralga (40km NNE of Goulburn) recorded 64.0mm, Golspie (20km NW of Taralga) 62.2 and Bigga (50km SE of Cowra) 57.0. The Cowra to Canowindra Road was cut 13km north of Cowra by flash flooding reported by police to be over 1m in depth over the road.
Rain moved across northern TAS from the west during the afternoon and evening, with a band of heavy rain and some thunderstorms immediately preceding the front during the late evening. Sheffield recorded 24.0mm in the 3 hours to midnight, while the heaviest totals for the 24 hours to 9am Thursday were on the northern flanks of the Tiers, including Erriba 61.8, Lorinna 51.0 and Mole Creek 50.8. There was low level flooding, and the Meander at Meander briefly rose above minor flood level early on Thursday morning.
Strong northerly winds were reported from the West Coast during the day. The AWS on the summit of Mt Read, 15km ENE of Zeehan, reported gale force average speeds at most observations during the day, and a wind gust of 126km/h around 3pm.
QLD, NT: Near record September heat
Temperatures came close to record territory today across the southern half of the NT and western and SW QLD. The area has been experiencing above to well-above average temperatures for the past 10 days, and today's top temperatures at Daly Waters, Brunette Downs, Elliott, Tennant Creek and Alice Springs in the NT and Mt Isa and Windorah in QLD were all within 1C of their record high September figures. Elliott reached 41.0C, while Birdsville, Bedourie, Boulia and Urandangie in QLD all reached or exceeded 40C. Both maxima and minima were 10 to 12C above average over a wide area, with many location reporting minima in the low 20s.