Friday, 1 June 2012 - Seasonal Climate Summary for Western Australia - Product code IDCKGC21R0

Western Australia in autumn 2012: Warm & dry autumn for southwest

• Rainfall: Near average for WA; 7th driest autumn for southwest WA
• Maximum temperature: average for WA; 5th warmest autumn for southwest WA
• Minimum temperature: 5th coolest autumn for WA; near average for southwest WA

Details Extremes Records Summaries Important notes the top

Rainfall

Rainfall during autumn 2012 was below to very much below average over much of western WA, particularly in the Southwest Land Division (SWLD) where a number of sites in the west and south observed their driest autumn on record. Below to very much below average rainfall was also evident in the central and southern Interior and Eucla. In contrast, above to very much above average rainfall was observed through most of the Kimberley and adjacent parts of the Pilbara and northern Interior, as well as small patches through central WA, primarily due to a monsoonal burst in mid-March and the passage of tropical cyclone Lua across the Pilbara coast and through central parts of the state. When averaged across the state as a whole, rainfall for autumn 2012 was near average, mostly due to generally above average rainfall in March along with a dry April and a very dry May.

Rainfall in the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay) during autumn 2012 was very much below average and ranked as the 7th driest autumn since comparable records commenced in 1900, largely due to the Lower Southwest recording its 5th driest March, a near average April, and a below average May. For the SWLD, rainfall in autumn 2012 ranked as the 5th driest on record.

Significant rainfall events during autumn 2012

• Tropical cyclone Lua crossed the Pilbara coast near Pardoo Roadhouse on 17 March and weakening over the eastern Gascoyne as it tracked southwards through central WA over subsequent days. Edjudina in the Goldfields registered 75.0 mm on the 19th when ex-tropical cyclone Lua passed through the region, the wettest March day in its 104 years of daily rainfall records. Troughton Island in the north Kmberley recorded a daily total of 260.6 mm on the 14th, which was the third wettest day in 27 years of record at the site and the highest daily rainfall in WA for autumn 2012.
• Dampier Downs in the west Kimberley recorded 341.6 mm in March, exceeding its previous wettest March of 340.3 mm in 2007, whilst Home Valley in the north Kimberley received 1194.0 mm, the wettest spot in WA during March 2012. From the 10th to the 15th, Home Valley experienced the brunt of a monsoonal burst with many days close to or over 100 mm, and one daily fall
  of 244.0 mm on the 13th.

Maximum temperature

Mean daily maximum temperatures during autumn 2012 mirrored the rainfall pattern, with above to very much above average daytime maxima in western and southeastern parts, and below to very much below average conditions in much of the Kimberley and adjacent parts of the Pilbara and northern Interior, as well as small patches through central WA. Areas of up to 3 °C below normal were evident in the east Kimberley, whilst small areas of up to 3 °C above normal mean maxima were observed between Carnarvon in the Gascoyne and Kalbarri in the Central West.

When averaged across the state, the mean maximum temperature for WA during autumn 2012 was near average; however, the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay) saw its 5th warmest autumn on record, following on from its 2nd warmest autumn in 2011. Comparable temperature records commenced in 1950.

Minimum temperature

Minimum temperatures were below to very much below average during autumn 2012 in the Kimberley, east Pilbara, east Gascoyne, northern Goldfields and in parts of the Interior, with mean minima up to 3 °C below normal in the southeast Kimberley and eastern Interior. Above average mean maxima were evident in coastal parts of the west Pilbara, west Gascoyne, and western and southern SWLD, while the remainder of the state was near average.

When averaged across the state, the mean minimum temperature for WA during autumn 2012 was very much below average, and the 5th lowest since comparable records commenced in 1950, whilst the the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay) was near average.

Eyre in the Eucla district experienced its coldest autumn nights in 50 years of record with a mean mininum temperature of 10.1 °C, 0.1 °C lower than its previous record set in autumn 1995.

Very cold nights were experienced during the latter part of May in the Lower Southwest due to a strong high pressure system stationed in the Bight. Numerous sites in the region recorded sub-zero temperatures and several sites recorded their coldest autumn night on record either on the 24th or 25th. Northam in the Central Wheat Belt registered -2.3 °C on the 25th, which was the lowest autumn temperature in 105 years of record at the site. Many sites in the Kimberley and Pilbara also experienced relatively cold nights in the last few days of autumn. Broome Airport registered a daily minimum temperature of 8.1 °C on the 27th followed by 7.7 °C on the 28th, breaking the previous the autumn record of 8.4 °C on the 28 May 1966 on consecutive days. Mount Elizabeth observed -0.9 °C on the 28th which was the first recorded sub-zero temperature in autumn in the Kimberley.

Notable Events

• Tropical cyclone Lua formed to the northwest of Karratha, well off the west Pilbara coast, on the afternoon of 13 March 2012. Lua moved northwestward and intensified to category two on the 15th before taking a u-turn and moving southeastward towards the WA coast. Lua intensified further to category three on the 16th and took a south-southeast track on the 17th as it intensified to category four and approached the east Pilbara coast. Lua crossed the coast near Pardoo Roadhouse on the afternoon of the 17th as a category four system. After landfall, Lua tracked southwards through the inland Pilbara and steadily weakened to below tropical cyclone strength on the morning of the 18th in the northeast Gascoyne. Significant damage was reported from Pardoo Roadhouse and the Yarrie mine site with uprooted trees and damage to buildings. Lua caused moderate to major flooding of the De Grey river system in the east Pilbara, particularly in the vicinity of Tumbinna Pool and Nullagine. Ex-tropical cyclone Lua moved through the Goldfields, Southeast Coastal, and Eucla between the 19th and 20th, bringing some heavy rainfall.
• A line of thunderstorms formed from around Cranbrook to Mt Barker to Albany around midday on 13 May. Large hail (1-2cm) was reported from the Stirling Ranges (east of Cranbrook) through to the Porongorup National Park with tree and car damage also reported.

Extremes Maps Records Summaries Important notes the top

Maps
	Observed	Anomaly	Decile rank
Total rainfall
Mean daily maximum temperatures
Mean daily minimum temperatures

Click on a map to show it full size in a pop-up window

Extremes Maps Records Summaries Important notes the top

Extremes Maps Records Summaries Important notes the top

Extremes Maps Records Summaries Important notes the top