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SIGNIFICANT WEATHER - DECEMBER 1999
Tropical cyclone John affected the Pilbara region of Western Australia. Severe thunderstorms affected most states during December and several locations recorded rainfall records during the month. Western Australia Forming on the 12th tropical cyclone John intensified to category 5 on the 14th and threatened the Pilbara coast with winds estimated at being up to 290 km/h. The cyclone crossed the coast at Whim Creek 120 kilometres northeast of Karratha on the 15th before weakening into a rain-bearing depression early on the 16th. High winds and flooding caused extensive structural damage at many stations in the Pilbara and mining operations were suspended at many sites. While Whim Creek suffered major damage and Newman experienced some flooding, major towns in the Pilbara escaped any serious damage. Tropical cyclone Ilsa developed well west of the state and initially moved eastwards. The cyclone moved to the south of Christmas Island on the 13th producing a heavy swell which caused some damage. On the 15th Ilsa tracked to the southeast towards the Pilbara coast briefly reaching category 2 status before weakening and crossed the coast near Sandfire Roadhouse at about midday on the 17th. Apart from producing heavy rainfall, Ilsa did not produce any significant damage. Queensland On the 10th severe thunderstorms affected areas between Warwick on the Darling Downs and eastward through southern Brisbane to the Gold Coast area and around the Lowood area. The most severe cell moved from Warwick to Boonah and Beenleigh. Reports were received of hail to golf ball size, wind damage to eleven buildings in Boonah including $500,000 damage to the local state high school destroying computers and classrooms. Many trees were blown over and estimates of wind to 100 km/h were reported. Extensive damage was caused to power lines in inaccessable areas with power loss to more than 35,000 homes. On the 30th the Sunshine Coast hinterland suffered extensive damage with towns of Palmwoods, Chevallum, Forest Glen and Nambour being most affected. Large hail fell and strong winds felled trees and toppled 60 to 70 powerlines. Two houses lost part of their roofs, sheds, tanks and many crops on fruit farms were destroyed. New South Wales On the 4th at Glen Innes (Northern Tablelands) 46mm of rain fell in 45 minutes. On the 8th gusts were reported at: Khancoban (Southern Tablelands) 100 km/h; Bombala (Southern Tablelands) 102 km/h; Broken Hill (Lower Western) 91 km/h and Parkes (Central West Slops) 96 km/h. On the 9th at Orange (Central Tablelands) a severe wind gust to 89 m/h was recorded. Damage to 2 homes were reported. At Blaxland (Central Tablelands) 50mm of rain fell in 25 minutes which caused local flash flooding. At Eden (South Coast) gusts to 102 km/h were recorded. A house lost part of a roof, trees were down and a telegraph pole snapped. At Dubbo (Central West Plains) 49 km/h wind gusts were reported. Large trees were blown down and a house was unroofed at Elong Elong. At Wallabadah (North West Slopes) 30 mm of rain fell in 25 minutes. On the 10th at Brunswick Heads (Northern Rivers) 5cm hail was reported. On the 23rd at Glenmore Park (Metropolitan) 55mm of rain fell in 20 minutes. On the 28th at Bathurst (Central Tablelands) 50.5mm of rain fell in 40 minutes. On the 30th at Maitland (Hunter) and Attunga (North West Slopes) 2cm hail was reported. At Ballina (Northern Rivers) 23.4mm of rain fell in 10 minutes. At Wingham (Mid-North Coast) 2.5cm hail was reported. At Kurindi Beach north of Coffs Harbour (Mid-North Coast) 2cm hail was reported. Victoria On the 8th severe thunderstorms which produced severe wind gusts and hail occurred in the Northeast district. In the Myrtleford area severe winds unroofed a house and trees were downed. Strong winds were also reported at Mitta Mitta, Harrietville, Rutherglen and along the Great Alpine road. Severe gusts were reported at Bairnsdale and raised dust was reported at Mildura and Winton. On the 16th heavy rain and thunderstorms were reported in the Northeast. At Mitta Mitta local flooding occurred and 87mm of rain was recorded in 24 hours. On the 26th heavy rain which led to flooding occurred in the Mallee, Wimmera, Northern Country and Central districts. Some of the highest 24 hour totals were Warrandyte 96mm and Maryborough 92mm. On the 27th thunderstorms which produced heavy rain leading to flash flooding occurred in the greater Metropolitan area. Flooding was reported at Werribee, Lower Plenty, Springvale, Broadmeadows, Northcote, Preston, Hastings and Campbellfield. Some locations recorded record highest daily rainfalls for December. South Australia Showers and thunderstorms caused flash flooding at Port Augusta and Stirling North on the 2nd with Port Augusta recording 43mm of rain. A power failure at Port Augusta prevented the town's electric stormwater pumps from working. On the 8th extensive thunderstorms were reported across the state. A severe thunderstorm developed between Arno Bay and Cowell, on Eyre Peninsula, late in the morning and moved slowly eastwards during the afternoon. Significant damage to property and crops were reported from towns along the path of the storm. The severest damage was reported from in and around Snowtown, in the Lower North district, with hailstones up to 4.5cm, heavy rain, 40 mm of rain in 1 hour and strong winds (122 km/h recorded at Snowtown AWS) causing considerable damage to crops, trees, powerlines and buildings along a corridor 8 to 10 km wide. Notable damage consisted of: Power poles twisted and bent to the ground; heavy farm machinery and grain bins being thrown several hundred metres through the air. A thoroughbred racing stud, near Port Broughton west of Snowtown lost 9 horses in the violent hail storm. The storm travelled over 400 kilometres in 5 hours, finally dissipating on the South Australian/New South Wales border, northeast of Paringa. On the 24th local roads in and around the Cowell area, on Eyre Peninsula, suffered minor flooding when a thunderstorm moved across the area. A dust storm ahead of the thunderstorm reduced visibility. Slow moving thunderstorms which developed on and east of the Mount Lofty Ranges moved westwards during the afternoon of the 25th. Flash flooding and strong winds from these storms resulted in property damage. In the Mount Lofty Ranges strong winds brought down trees; At Eudunda (Lower Murray Valley) flash flooding washed away a road bridge, washed cars away and flooded homes. At Millicent (Lower Southeast) flash flooding damaged 3 homes. In the northern suburbs of Adelaide, flash flooding closed roads and caused minor flooding to homes. Paringa, near Renmark, suffered flooding to properties. On the 26th at Innamincka, in the Far North of the State, received 43mm of rain in 45 minutes from a downpour in the early evening. Western Australia On the 28th and 29th thunderstorms were experienced over a considerable area from the Pilbara to the Lower West Coast. Maya in the Central West District recorded 117.2mm of rain in the 24th hours to 9am on the 29th and several other sites in the wheatbelt registered falls over 50mm. A hailstorm damaged fruit orchards in the Perth hills on the 29th. Victoria On the 2nd severe gusts were recorded in southern and mountain areas: Mt Hotham 132 km/h, Bairnsdale 115 km/h, Falls Creek 106 km/h, Sale 98 km/h, Haines Saddle 91 km/h. Duststorms were reported at Swan Reach (East Gippsland and Melton Reservoir. Tasmania Gusts exceeding 90 km/h were reported at: Cape Grim on the 28th; Derwent Estuary (near Hobart) on the 3rd, 9th, 12th, 17th and 18th; Eddystone Point on the 29th; Flinders Island Airport on the 3rd; Hartz Mountain on the 4th, 16th and 18th; Maatsuyker Island on 16th - 18th; and Mount Wellington on the 3rd, 11th, 12th, 16th - 18th and the 28th.
Western Australia On the 30th and 31st lightning sparked a bushfire that burnt about 45,000 hectares in the Beekeepers Nature Reserve near Leeman. Queensland There were two periods during December which required flood warnings to be issued; early in the month in a number of the western rivers and in late December commencing on the 24th, a low pressure system caused heavy rainfall along the coast from Innisfail to the NSW border. Heavy rainfall ending on the 24th caused significant river rises in the Tully and Johnstone Rivers. This resulted in moderate flooding in the Tully but the Johnstone River at Innisfail peaked just below the minor flood level. The low pressure system which caused this heavy rainfall caused significant river rises in most smaller coastal rivers and streams to the New South Wales border and minor flooding in the Herbert, Haughton and Don Rivers. Rainfalls recorded during the period just after Christmas caused river rises and moderate flooding along the Paroo River to Hungerford which continued into the new year. At the start of December, flooding in the Bulloo River started from November and continued up to the 7th of December when the flood warning was finalised. Heavy rainfall towards the end of December again resulted in minor to moderate flooding in the Bulloo River which continued into the new year. The minor to moderate flooding which commenced in the Thomson and lower Barcoo Rivers in November continued into December with the Cooper Creek at Windorah reaching a peak on the 3rd of December with major flooding. By the 6th flood warnings had subsided sufficiently for warnings to be finalised. Renewed rises in the lower Thomson and Barcoo Rivers followed rainfalls of the 28th and again caused major flooding in the Windorah area which continued into the new year.
Note: Some statistical records mentioned in this report are based on data that have yet to be fully validated.
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