SIGNIFICANT WEATHER - MARCH 2000

Introduction Tropical Cyclones Thunderstorms Wind Bushfires Flooding Temperature
Rainfall

INTRODUCTION

Tropical cyclone Steve caused extensive disruption to communities across the north and west of Australia as it moved across the Queensland coast near Cairns in late February then across the Northern Territory, down the Western Australia coast and finally moving southeastwards through the Great Australian Bight in mid March. Heavy rainfall, including numerous records, and flooding were experienced over parts of the Northern Territory and Western Australia.

TROPICAL CYCLONES

Western Australia/Northern Territory

Tropical cyclone Norman was named on the 1st while located approximately 280km to the northnortheast of Karratha. It followed a westerly track across the Indian Ocean and by the 3rd the westward moving system had intensified to category 5 with a central pressure estimated at 920 hPa, while about 780 km to the westnorthwest of Exmouth. During the 6th the cyclone changed direction to a southerly track. Tropical cyclone Norman weakened during the 8th to category 1 and had no direct impact on Western Australia.

Tropical cyclone Steve initially formed over the Coral Sea off the Queensland coast. During the 27th of February the cyclone crossed the Queensland coast near Cairns. As a tropical low the system moved over waters of the Gulf of Carpentaria in a northwesterly direction. Tropical cyclone Steve re-intensified to category 1 and crossed the Northern Territory coast to the north of Port McArthur during the 1st of March. Ex-tropical cyclone Steve moved westwards across the Northern Territory causing widespread flooding in the Katherine, Daly and Victoria regions, and over the Kimberley region of Western Australia during the 3rd and 4th. Early on the 5th the system moved offshore near Broome and was re-classified as a tropical cyclone while located approximately 200 km to the westsouthwest of Broome. The cyclone continued to follow a southwesterly track and passed just north of the towns of Port Hedland and Karratha during the 6th as a category 2 cyclone. Tropical cyclone Steve crossed the coast near Mardie (approximately 70 km to the east of Onslow) on the 7th with a central pressure estimated to be 975 hPa. The system was downgraded to category 1 as it moved over the west Pilbara.

At around midnight on the 7th tropical cyclone Steve moved offshore about 175 km to the north of Carnarvon. During the 8th the cyclone turned towards the south and remained very close to the coast. On the 9th the low was located about 80km to the south of Carnarvon and moving towards the southeast at 10 km/h. The low moved over land and maintained a southeasterly track across the Gascoyne, Murchison and Goldfields. On the afternoon of the 11th the low moved offshore across the Western Australian coastline to the east of Esperance and over the waters of the Great Australian Bight.

The very heavy rainfall associated with the system produced widespread flooding in northern parts of the state including the Gascoyne region. Much of the Kimberley, Pilbara and Gascoyne reported cumulative rainfall totals in excess of 100mm. Higher falls greater than 300mm were recorded near the 80 Mile Beach. Parts of the western Pilbara and northern Gascoyne received totals that ranged from 200 to 300mm. Several sites reported highest on record daily rainfall amounts including Mandora (281.3mm on the 6th) and Yaringa, south east of Carnarvon, (175.0mm on the 9th). Rainfall ranging from 50mm to 100mm continued over inland parts extending in a southeasterly direction from the west Gascoyne to the South Coast near Esperance. Flooding occurred in the Esperance area and a number of roads and bridges were washed away. Lort River recorded 115.4mm and Salmon Gums Research Station recorded 90.8mm of rain on the 11th.

A developing tropical low was named tropical cyclone Olga on the 17th while located approximately 570 km to the north of Exmouth. Following a generalised southwest track tropical cyclone Olga intensified to a category 2 cyclone during the 18th with a central pressure of 980 hPa. By the 20th the system had weakened to a tropical low while located about 970 km to the west of Carnarvon. The system had no direct effect on Western Australia.

THUNDERSTORMS

New South Wales

On the 5th at Katoomba (Central Tablelands) 2cm in diameter hail and 37mm of rain fell in 30 minutes. Flash flooding was reported. Also on the same day at Nundle (North West Slopes) 100mm of rain fell in 60 minutes. Sheepyards were severely damaged by the water which was the highest level in the creek for 50 years. At Gloucester (Mid-North Coast) 22mm of rain fell in 10 minutes.
On the 9th at Bathurst (Central tablelands) 20mm of rain fell in 5 minutes.
On the 19th at Baulkham Hills (Metropolitan) 42.5mm of rain fell in 60 minutes. There were some reports of flash flooding in the area.

WIND

Victoria

A gusty southwest change on the 22nd produced severe gusts to 90 km/h and raised dust in the Wimmera district, south of Horsham.

Tasmania

Gales on the 18th disrupted power supplies across much of the State. On the same day four people were rescued near Cockle Creek after their boat capsized. Mean wind speeds exceeding 90 km/h were reported at Maatsuyker Island, Mount Wellington and Scotts Peak Dam.
Gusts exceeding 90 km/h were reported at Barren Tier on the 18th; Cape Grim on the 12th, 13th, 14th, 18th, 22nd and 23rd; at Derwent Estuary TERS site on the 14th, 18th, 22nd, 23rd and 29th; on Hartz Mountain on the 2nd, 14th, 18th, 23rd and 28th; at Hobart on the 18th; at Mt Wellington on the 2nd, 13th, 14th, 18th, 20th, 22nd, 23rd, 28th, 29th and 30th.

South Australia

A vigorous cold front brought strong winds and driving rain to most of the southern settled areas during the afternoon of the 22nd. The Adelaide Plains and the Mount Lofty Ranges districts were the most affected with localised flash flooding and power cuts due to the strong winds.

BUSHFIRES

Tasmania

On the 2nd bushfires occurred at various locations in the north, east and south of the State but no serious damage was reported.

FLOODING

Queensland

During March major flooding continued in the river systems in western Queensland, following the heavy rainfall over far western catchments in February. Flooding also occurred in several north tropical rivers during the middle of the month.

Heavy rainfall overnight on the 16th which continued during the 17th resulted in moderate to major flooding throughout the Haughton River. River levels at Giru reached 2.70 metres early morning on the 18th with major flooding, the highest level since the start of records in 1978. The flood warning was finalised for the Haughton River on the 19th when all river levels had fallen below the minor flood level.

A flood warning was current at the beginning of the month for the Paroo River with minor flooding in the downstream reaches. Further rainfall resulted in renewed rises in the Paroo River and major flooding at Humeburn on the 12th. Major flooding continued downstream with the main floodwaters peaking at Hungerford at 2.0 metres on the 18th.

At the beginning of the month major flooding was still easing in the Thomson River at Longreach, with the main floodwaters in the Jundah area. Major flooding continued downstream into Cooper Creek during the month with the floodwaters peaking at Windorah on the 3rd. River levels peaked at Durham Downs on the 17th and by the end of March the floodwaters were approaching Nappa Merrie.

Minor to moderate flooding occurred throughout the Georgina River and Eyre Creek system at the beginning of March with the main floodwaters still being in the upper reaches of the Georgina River in the Urandangie area. The floodwaters moved very slowly downstream during the month peaking at Marion Downs on the 12th with major flooding and Glengyle on the 22nd with moderate flooding. The flood warning for the Georgina River system was finalised on the 22nd.

Northern Territory

Heavy rains were experienced across the Top End as a result to tropical cyclone Steve:

On the 1st the Hodgson River at Hodgson River Station rose quickly to 12.35 metres and threatened the homestead following falls of nearly 200mm of rain in the catchment. Nutwood Downs recorded 185mm of rain.

The Katherine River at Katherine rose quickly from 4 metres on the 1st to 8.9 metres on the 2nd peaking at 17.45 metres on the 3rd.

On the 2nd - 3rd the Cullen River cut the highway south of Pine Creek. Also on the 2nd, the Waterhouse River rose after heavy rainfall in the catchment (205mm at Upper Waterhouse) and entered the Beswick community causing some relocations to higher ground. Further downstream the Djilkminggan community of 300 people were evacuated to Mataranka.

TEMPERATURE

RAINFALL

Note: Some statistical records mentioned in this report are based on data that have yet to be fully validated.