Australian
Weather NewsAustralian
Weather NewsFriday 31 October 1997, 13.10 EDST updated 31/10/97 19.00
Thunderstorms, heavy rain, flash flooding, gales, dust storms and remarkable variations in temperature have occurred and are continuing in the southeastern states as a rapidly deepening low of 996hPa and associated active troughs move slowly southeastwards from near Mildura at 09.00EST. Between midnight and 06.00 Friday, the barometer at Renmark PO dropped 9.6hPa, tightening gradients and increasing wind speeds to the east and west of the trough. The 09.00 Friday upper air reports from Adelaide and Laverton (west of Melbourne) showed an almost completely saturated atmosphere in the bottom 20,000 feet or more, with moderate to high instability (tot tots at Woomera 48, Laverton 49, Wagga 46 and Adelaide 41.)
In South Australia, moderate to heavy rain has fallen over all but the far north and west of the state, with registrations for the 24 hours to 09.00 CDST generally between 20 and 75mm. Heaviest falls, mostly between 50 and 70mm were in the Lower North, Yorke Peninsula, Mount Lofty Ranges and the Adelaide area, and included Watervale 96, Auburn 94 and Snowtown 83 in the Lower North; Kadina 79, Port Vincent 76 and Ardrossan 75 on the Yorke Peninsula; Uraidla 78 and Gumeracha 72 in the Lofties; and Parafield 83 and North Adelaide 78 on the Adelaide Plains. Adelaide City's fall of 56mm was the highest daily October registration since the record 57mm in 1908. Rain began falling in the northwest on Thursday morning as cloud along a developing trough line thickened and moved rapidly southeast to cover most of eastern SA by mid afternoon. Whilst embedded thunderstorm contributed to the high rain totals, much of the rain fell steadily through the 24 hour period -- Whyalla, for example, reported 11, 9, 10, 8, 4, 7, 6 and 8mm at each 3 hourly observation at and from midday Thursday.
The heaviest rain, accompanied by severe southern winds averaging more than 65 km/h and gusting to more than 100km/h, occurred during Friday morning in and around Adelaide. The gales unroofed many houses and brought down trees, whilst flooded roads caused traffic problems all morning. State Emergency Services crews, augmented by country and metropolitan fire service personnel, have been working all night and were fully stretched, with people needing help to repair storm damage having to wait several hours. Adelaide City reported wind gusts to 43 knots around midnight; Cape Borda's top gust overnight was reported as 60 knots. Murray Bridge recorded 63mm of rain between 03.00 and 09.00; Lameroo received 23mm and Parafield 22 between 03.00 and 06.00, and between 09.00 and 12.00 Friday, Parawa reported 22 and Strathalbyn 26mm..
Cold air circulating behind the deepening low produced some dramatic temperature variations. Stations in the west of South Australia that were reporting maximum temperatures in the mid thirties on Wednesday only reached the mid teens on Thursday, Cook's top temperature between 09.00 and 15.00 Thursday of 13 being 14 below average. Another unusual temperature variation was with height: at 12.00 Friday, the temperature at Cape Willoughby at sea level was 10.6, but at Mount Lofty at 730 metres it was 14.2, both with gale or near galeforce winds.
In Victoria and southern NSW, a line of storms moved across the region from the northwest late Thursday afternoon and evening, producing moderate dust storms in western NSW and the Riverina, and rain to about 10mm with thunderstorms. Geelong Airport, however, recorded 22mm in storms between 15.00 and 21.00. More widespread and persistent rain set in across the western half of Victoria around midnight, with widespread totals of 5 to 15mm between 21.00 Thursday and 03.00 Friday (Falls Creek 19, Horsham 17). Between 03.00 and 09.00 Friday, rain spread throughout the state. Most 24 hour totals to 09.00 in Victoria were between 10 and 30mm, with the highest reports Ararat 54 (Western Plains) and Ballan 47, Geelong Airport 45 and Meredith 48 (West Central).
In NSW and Queensland, high temperatures were recorded on Thursday in the northerlies ahead of the trough. Highest maxima were 44 at Birdsville (+12 on normal), 43 at Windorah, 42 at Thargomindah and Urandangie, and 41 at Boulia, Longreach, Quilpie, Moomba (SA) and Tibooburra Airport. On Friday morning, minimum temperatures across western, central and southern NSW, southwestern Queensland and northern Victoria were generally 7 to 12 above average, the observer at Coonabarabran reporting that the 06.00 temperature of 19.9 was a record for that time.
Friday 31 October 1997, 10.45 EDST
After a long period of generally settled weather, persistent hot northerly winds ahead of a slow-moving trough over South Australia brought the first heatwave of summer to eastern SA, Vic, Tas and southern NSW during the weekend of 25-26 October 1997. Many centres in this area reported daytime temperatures more than 10 degrees above the October average on both days, with an exceptionally warm Saturday night in between. Adelaide Airport reported a top temperature of 34.5 on the Saturday, 14 above average, before a cool change moved through early on Sunday. Melbourne Airport recorded 32.9 and Hobart Airport 31 on the Sunday, both 14 up on normal.
Greatest departure from normal for maximum temps on Saturday was +15 degrees, shared by Elliston 36, Whyalla 38, Edinburgh Airport 35.5 and Narracorte 35 (SA). Greatest departure for Sunday morning minimum temperatures was +12, shared by Yongala 17.6, Port Pirie 24, Renmark 23 and Meningie 21.5 (SA), most of these being recorded at 09.00 CDST Sunday after the cool change had moved through -- Adelaide City's 03.00 temperature on Sunday morning was a whopping 28.6 degrees. On Sunday, top maximum temp departure was again +15, at Bairnsdale 35, Moorabin Airport 34 and Laverton Airport 34 (Vic).