Monday, 1 August 2011 - Monthly Climate Summary for Western Australia - Product code IDCKGC21R0

Western Australia in July 2011: Warm nights in WA.

• Rainfall: Above average for WA; near average in southwest WA.
• Maximum temperature: Near average for WA.
• Minimum temperature: Fourth warmest on record for WA; near average for southwest WA.

Details Extremes Records Summaries Important notes the top

Rainfall

Rainfall during July 2011 was above to very much above average over parts of the Pilbara, Gascoyne, Goldfields, Interior and Eucla mainly due to a number of cloudbands crossing WA during the month. Rainfall totals in the Southwest Land Division (SWLD) were mostly close to average, although some areas received above average rainfall and some below (see July 2011 rainfall totals & deciles)

When averaged across the state, rainfall during July 2011 was above average. A number of strong cold fronts crossed the southwest of the state during the latter part of July 2011 resulting in the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay) receiving near average rainfall, and Bickley recording 270.0 mm for the month, the highest monthly total for WA. Interestingly the Lower Southwest received more rainfall in the June to July period in 2011 than was recorded during the entire winter of 2010, though despite this, January to July rainfall during 2011 was still very much below average.

Milly Milly in the Gascoyne observed its wettest July day in 101 years of record with 50.0 mm on the 10th as an intense cloudband developed over WA, while Wynyangoo (near Mount Magnet) observed its wettest July in 48 years of record as a consequence of the cloudband and other rainfall events during the month that resulted in 12 rain days at the station.

The passage of a cold front on the 22nd produced a tornado near Serpentine during the afternoon and flash flooding in Fremantle. Another frontal system on the 25th produced sustained rainfall over Cape Leeuwin which recorded 30.4 mm in 1 hour and a total of 64.8 mm in 7 hours, which is a one in 20 to 50 year event. A strong cold front moved through southwest parts of WA from late in the afternoon on the 27th bringing heavy showers, thunderstorms, severe wind gusts and a possible tornado in Waroona during the evening. A deep low then passed to the south of WA during the morning of the 28th with a secondary front moving through southern parts of WA bringing further rainfall. A deep low to the south of the state produced a strong westerly gradient over the south west of WA with embedded fronts from the 29th through to the end of the month

Maximum temperature

July 2011 maximum temperatures were above to very much above average in the western Kimberley where temperatures were up to 3 °C above normal, while the remainder of WA saw either near average or above average daytime mean temperatures (see July 2011 mean maximum temperature decile & anomaly maps)

When averaged across the state during July 2011, the mean daily maximum temperature was near average in WA.

A cooler than normal start to the month was experienced in central and southern parts of WA, culminating in very cold days on the 10th and 11th due to a cloudband over much of the state. Bulga Downs observed the coldest day in WA for July 2011 during this time, with a maximum of just 8.9 °C on both the 10th and 11th, and a number of sites in the northern Goldfields, southern Gascoyne and northern SWLD broke their lowest July daily maximum temperature records.

Minimum temperature

Apart from most of the Kimberley and Southwest districts of WA, which saw near average overnight minima, mean minimum temperatures for July were above to very much above average over almost all of WA, with an area of highest on record in the Eucla, Goldfields and southeast SWLD (see July 2011 minimum temperature decile & anomaly maps). Eucla and Hyden recorded their the warmest July on record in terms of mean daily minimum temperature in 74 and 38 years of record respectively.

When averaged across the state, July 2011 was the fourth warmest in terms of mean minimum temperature since comparable records commenced in 1950.

An unusually warm night was experienced on the last night of the month in much of the SWLD in a strong westerly pressure gradient, and Ravensthorpe observed its warmest July night in 49 years of record.

Extremes Records Summaries Important notes the top

Extremes Records Summaries Important notes the top

Extremes Records Summaries Important notes the top