Thursday, 1 March 2012 - Monthly Climate Summary for Western Australia - Product code IDCKGC11R0

Western Australia in February 2012: Warmer nights in Southwest

• Rainfall: near average for WA.
• Maximum temperature: near average for WA.
• Minimum temperature: below average for WA; above average in southwest WA.

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Rainfall

Rainfall during February 2012 was below average in the north Kimberley, parts of the Pilbara and inland Gascoyne, and in the eastern Eucla, mainly due to a generally quiet wet season across the north of the state. In contrast, above average rainfall was observed in parts of the western and central Southwest Land Division (SWLD), and the southwest Gascoyne, mainly due to ex-TC Iggy which brought rainfall to the SWLD and neighbouring districts at the beginning of the month. Above average rainfall was also observed in eastern parts of the Interior. When averaged across the state, February 2012 rainfall was near average. The Lower Southwest (southwest a line from Jurien Bay to Bremer Bay) as a whole, as well as the SWLD, also saw near average rainfall for the month.

February 2012 began with Tropical Cyclone Iggy located well west of the Gascoyne coast. Iggy rapidly weakened to be below tropical cyclone strength as it tracked eastward towards the Central West on the 2nd . Ex-TC Iggy brought rainfall to much of the SWLD as it approached the coast and moved across northern parts of the SWLD on the 2nd and 3rd, with some heavy falls during the evening of the 2nd and early on the 3rd in western parts of the Central West and Lower West, mainly in the Perth to Lancelin area where a few sites broke their highest daily rainfall records for February.

A distinct break in the wet season saw generally dry conditions over the northern half of the state over the first few weeks of February, before more widespread shower and thunderstorm activity returned to the Kimberley from the 20th. Apart from TC Iggy early in the month, no other tropical cyclones were observed in the WA region during February 2012. Central and southern parts of the state saw intermittent showers and thunderstorms throughout the month, however, without a strong monsoon to the northwest acting as a moisture source, rainfall was generally close to or below average.

Maximum temperature

Above to very much above average maximum temperatures were observed in the Kimberley during February 2012, with much of the district seeing mean maxima up to 2 °C above normal mainly due to hot dry conditions in the early and middle stages of the month. Coastal parts of the Eucla, and western parts of the Southwest district also saw above average daytime temperatures, whilst the remainder of the state was mostly near average. Only central eastern parts of the Interior reported below average maximum temperatures, with means to 2 °C below normal. When averaged across the state, the mean maximum temperature for WA during February 2012 was near average. Daytime temperatures over the Lower Southwest although near normal were marginally cooler than the long-term average during February 2012, which is the first month that a below normal mean maximum has been recorded in the region since December 2010, and only the second below average month since October 2009.

February 2012 began with a hot day over the SWLD, continuing the hot spell that began late January, before a cooler change due to the passage of ex-TC Iggy and a developing ridge extended across the division on the 2nd, extending across much of southern WA in subsequent days. A break in the wet season saw hot conditions across parts of northern WA for much of the beginning of the month, extending into central parts of the state mid-month, with many stations regularly observing mid-40 °C temperatures, and Roebourne recorded the hottest day for WA in February 2012 with 45.7 °C. A broad trough over central WA allowed hot conditions to extend into the southeast of the state during mid-February, with temperatures exceeding 40 °C, before a ridge brought a cool change on the 20th. A trough near the west coast on the 22nd moved slowly eastwards through the SWLD and southeast of the state from the 22nd to the 25th, bringing very hot conditions east of the trough, particularly in south coast districts.

Minimum temperature

February 2012 saw above average mean minimum temperatures over most of the SWLD and adjacent western Goldfields, and in isolated parts near the coast in the Gascoyne, west Pilbara and north Kimberley. Below to very much below normal overnight temperatures were experienced in much of the west and south Kimberley, east Pilbara, Interior and Eucla, with areas 2 to 3 °C below average in the southeastern Interior and western Eucla. When averaged across the state, the mean minimum temperature for WA was below average. In contrast, the Lower Southwest recorded above average overnight temperatures, continuing a run of consecutive above average monthly minima that started in November 2010.

A hot night was observed in eastern parts of the SWLD on the 2nd, with cloudy conditions and warm northerly winds resulting in Hyden in the Great Southern recording its hottest night in 37 years of record. Cool nights extended across southern WA from the 5th due to a ridge to the south, and dominated most of the state through to the 12th. The passage of troughs during the middle and latter parts of the month brought warm nights to central and southern WA, however, the month ended with a ridge directing cooler air across much of the southern half.

Other Phenomena

Tropical Cyclone Iggy formed to the northwest of Exmouth, off the west Pilbara coast, on the morning of 26 January 2012 and remained offshore to the west of WA as it moved southward. On 1 February, Iggy was located approximately 500 km west of the Gascoyne coast and moved in a generally southerly direction as a category 2 system but tracked more to the southeast as the day progressed and rapidly weakened to be below tropical cyclone strength on the morning of the 2nd as it tracked eastward towards the Central West. Ex-TC Iggy moved through northern parts of the SWLD on the 3rd and brought heavy rainfall to locations in the northern Lower West and southern Central West, as well as near gale force winds to coastal locations in the Central West. As Iggy moved parallel with the west coast in late January and early February, an associated tidal surge was recorded at most towns from Onslow to Perth, the peak being 80 cm at Geraldton and 70 cm at Fremantle on 2 February.

Extremes Maps Records Summaries Important notes the top

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

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Extremes Maps Records Summaries Important notes the top