Thursday, 1 August 2013 - Monthly Climate Summary for Western Australia - Product code IDCKGC11R0

Western Australia in July 2013: a dry month

• Rainfall: below average for WA
• Maximum temperature: above average for WA
• Minimum temperature: near average for WA

Extremes Maps Records Summaries Important notes the top

Rainfall

Rainfall in July 2013 was below to very much below average over the western and southern Gascoyne, central Goldfields, and much of the Southwest Land Division (SWLD). Pockets of above to very much above average rainfall were observed in the Great Southern, western Southeast Coastal, southern Goldfields, and Eucla, largely as a result of a significant rainfall event that moved through these areas from the 11th to 13th. Little if any rainfall was reported across much of the Pilbara, Kimberley, and northern Interior during July 2013, and although large parts of the Pilbara and west Kimberley reported below to very much below average rainfall, it is typically a dry month in the north. The remainder of the State saw near average rainfall.

For WA as a whole, as well as for the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay) and the SWLD, rainfall during July 2013 was below average. As a result of June being extremely dry in the SWLD, the June-July period for both the Lower Southwest and SWLD was the fourth driest since comparable records commenced in 1900. Only 1976, 2006 and 2001 were drier in the Lower West, whilst for the SWLD as a whole, only 1976, 2006, and 1977 were drier.

A number of weak cold fronts and subsequent onshore flow produced mainly light rainfall in the SWLD and Eucla between the 2nd and the 7th, with some moderate falls near the SWLD south coast, while a weak trough over central parts of the State produced areas of rain in the northern Goldfields on the 7th. A cold front and associated cloudband moved through southern WA on the 9th and 10th, bringing widespread rainfall to the SWLD and southern Goldfields with moderate falls in the Lowest West and adjacent Southwest district. A complex low pressure system moved across the southern half of the State into the Bight between the 11th and 13th bringing widespread significant rainfall to the SWLD and adjacent Gascoyne and Goldfields. A number of sites in the Central Wheat Belt, Great Southern, and South and Southeast Coastal recorded their wettest July day on record during the event, including Tamaru in the South Coastal which recorded 99.3 mm in the 24 hours to 9am on the 13th, its wettest July day in 48 years of record. A slow moving cold front moved through the SWLD on the 15th bring widespread showers to the region and heavy falls of 60 mm to 100 mm were reported in the Margaret River region of the Southwest district with some localised flooding. A daily total of 99.4 mm at Witchcliffe on the 15th was the highest daily rainfall of the month in the State. A strong cold front moved through the SWLD, Gascoyne, Goldfields, and Eucla on the 16th and 17th, bringing widespread rainfall to these regions, with thunderstorms and damaging winds reported in the SWLD. A strong cold front and cloudband moved across western and southern WA on the 24th to produce widespread rainfall in the southern Gascoyne and SWLD, with moderate to heavy falls in the Southwest and Lower West districts. Wokalup in the Southwest recorded 63.6 mm in the 24 hours to 9am on the 24th, its highest July daily fall in 62 years of record. Another strong cold front and cloudband moved across the southern half of WA on the 26th and 27th producing widespread rainfall with moderate falls, particularly in the Lower West. A weak cold front brushed through the southwest corner overnight on the 31st bringing generally light showers to much of the SWLD with moderate falls observed in the Southwest and Lower West.

Maximum temperature

Above to very much above average mean maximum temperatures were observed in the Kimberley and adjacent Northern Interior, the southern Pilbara, west Gascoyne, SWLD, eastern Eucla, and eastern Southern Interior, with areas up to 3 °C warmer than normal in the eastern Eucla. Much of the Pilbara, east Gascoyne, Goldfields, Southern Interior, and Southeast Coastal saw near average temperatures.

Averaged across the state as a whole, the mean maximum temperature for WA in July 2013 was above average. For the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay) the mean maximum temperature was also above average.

The first week or so of July 2013 saw varying cool to warm conditions across the State, but from the 9th to 16th warmer than normal conditions dominated most regions. Relatively cool conditions were most common from the 17th to 21st, but from the 23rd to the end of the month, mostly warmer than normal conditions prevailed. Wet and cloudy conditions resulted in a cold day in the Goldfields and southern Gascoyne on the 7th, and Yeelirrie in the Goldfields recorded the lowest maximum temperature of the month in the State with 9.3 °C on the 7th, its second coldest July day in 39 years of record, only behind a maximum of 9.0 °C on 13 July 2004. Light winds and a warming airmass in the north saw consecutive hot days in the Kimberley on the 14th and 15th with daily maxima over 35.0 °C at a number of sites. Curtin Aerodrome in the west Kimberley observed the highest maximum temperature of the month in the State with 36.5 °C on the 14th, which was the second hottest July day in 21 years of record at the site, only behind 36.7 °C on 30 July 1992. A cold day was observed in much of the SWLD on the 17th as cold southerly winds and wet conditions swept across the region. Both Manjimup and Mount Barker recorded a daily maximum temperature of 9.6 °C.

Minimum temperatures

A broad area extending from the Pilbara, through the adjacent Northern Interior, Southern Interior, eastern Goldfields, and Eucla, saw above to very much above average mean minimum temperatures in July 2013, as did parts of the east Kimberley. Means up to 3 °C warmer than normal were recorded in the inland southern Pilbara and far northern Gascoyne, as well as in the far east Kimberley. In contrast, below to very much below average mean minimum temperatures occurred in the southwest Gascoyne and much of the northern and central SWLD, with means up to 2 °C cooler than normal reported in these regions.

Averaged across the state as a whole, the mean minimum temperature for WA in July 2013 was near average, while averaged across the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay) the mean minimum temperature was also near average.

Varying conditions, in terms of minimum temperatures, were reported across the State during the beginning of July but from the 10th to 17th predominantly warmer than normal conditions prevailed, before returning to more variable conditions for the remainder of the month. Persistent fresh northwesterly winds and above average sea surface temperatures resulted in a record high minimum temperature at Cape Leeuwin on the 1st. A minimum of 17.7 °C was the highest minimum during July in 106 years of record, easily exceeding the previous record of 16.7 °C on 5 July 1913. In contrast, cold nights were reported across southern WA from the 5th to the 9th as a result of generally clear skies and light winds. Many sub-zero temperatures were reported, aided by particularly dry soils following an extremely dry June, and a number of sites in the SWLD experienced their coldest or equal coldest night in July on record on the 8th. Wandering in the Great Southern recorded a minimum of -4.8 °C on the 8th, the lowest temperature recorded in WA in July 2013. Cloudy skies and northwesterly winds on the 15th kept temperatures unusually mild overnight in southwest WA with stations in the Southwest and South Coastal districts breaking their highest minimum temperature on record for July. Cold nights were again observed in western parts of the State between the 18th and 22nd as Lancelin in the Lower West recorded a temperature of 1.5 °C on the 21st, its equal lowest temperature in 49 years of record, equal with a minimum of 1.5 °C on 25 July 1979.

Other Phenomena

A series of cold fronts moved through the SWLD between the 15th and 17th, bringing heavy rainfall and damaging winds to southern districts. Flash flooding was reported in the Southwest as rainfall totals in the 60 mm to 100 mm range were reported on the morning of the 15th and a river crossing was washed away as a result. Severe wind gusts of 100 km/h to 115 km/h were recorded at coastal sites in the Lower West, Southwest, and Southeast Coastal on the 16th and 17th, resulting in more than 6000 homes in the Perth metropolitan area and southwest WA without power. The WA Department of Fire and Emergency Services (DFES) received more than 138 calls for assistance.

Numerous damaging wind gusts (between 90 km/h and 102 km/h) were recorded across southern WA as a strong cut off low and associated cold front passed over the region from the 25th to the 27th. DFES received a total 53 calls for help during this period, with damage reported in the Mandurah suburbs of Halls Head and Silver Sands, as well as in Kalgoorlie, Moora, and York. In the Perth metropolitan area, 22 calls for assistance were received overnight on the 26th and on the morning of the 27th with damage occurring in the northern suburbs of Heathridge and Beldon.

Extremes Maps Records Summaries Important notes the top

Extremes Maps Records Summaries Important notes the top

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

Extremes Maps Records Summaries Important notes the top

Extremes Maps Records Summaries Important notes the top

Extremes Maps Records Summaries Important notes the top