Monday, 3 December 2012 - Monthly Climate Summary for Western Australia - Product code IDCKGC21R0

Western Australia in November 2012: A wet month in WA

• Rainfall: very much above average for WA
• Maximum temperature: above average for WA; near average for southwest WA
• Minimum temperature: above average for WA; near average in southwest WA

Extremes Maps Records Summaries Important notes the top

Rainfall

Rainfall during November 2012 was above to very much above average through most of the Southwest Land Division (SWLD), particularly in northern and eastern parts where numerous sites, many with over 100 years of record, observed their wettest November on record. Rainfall was also above to very much above average in the west and south Gascoyne, the Goldfields, east Pilbara, Southern Interior, western Eucla, and parts of the Kimberley, with some sites in the Kimberley observing record daily and monthly totals due to thunderstorm activity. The only part of WA to experience significant below average rainfall was in eastern parts of the Northern Interior, and northeastern Southern Interior.

Averaged across the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay), November rainfall was very much above average and in the highest 10% of observations, ranking as 11th highest on record. For the SWLD, area averaged rainfall was 3rd highest on record, while averaged across the state as a whole, November 2012 rainfall ranked as 11th highest on record. Comparable area-averaged records commenced in 1900.

The wet November in the Lower Southwest during November raised the year to date rainfall out of the lowest 10% of records, however the January to November total remains below average, currently ranking as 14th lowest on record, largely a result of the 8th driest autumn and 8th driest winter. For the SWLD, January to November rainfall ranked as 12th lowest on record.

A cloudband extending over much of western and southern WA on the last day of October, resulted in rain, showers and thunderstorms, with moderate to heavy falls observed in the 24 hours to 9am on 1 November in eastern parts of the SWLD. The heaviest daily fall was 37.6 mm at Merredin (Central Wheat Belt), which is its wettest November day in 105 years of record. Severe thunderstorms developed during the afternoon of the 1st in the Central West to the east and southeast of Geraldton and moved in a southerly direction before clearing during the evening. A particularly strong cell developed just to the north of Badgingarra and moved southward before dissapating to the southeast of Lancelin. Badgingarra (DAFWA) reported 39.8 mm in the 24 hours to 9am on the 2nd, with 31.6 mm of this total recorded in 12 minutes between 1358 WST and 1410 WST on the 1st; a greater than 1 in 100 year rainfall event. A cold front moved through western and southern WA late on the 3rd and on the 4th, with moderate to heavy falls observed in the Lower West and Southwest districts. The passage of the front across the SWLD was preceeded by a report of a tornado near Wonnerup during the afternoon of the 3rd. Moderate to heavy rainfall was observed in the 24 hours to 9am on the 22nd in northern, central, and eastern parts of the Southwest Land Division, the Goldfields, and Southern Interior. Seven Oaks in the Central Wheat Belt observed its second wettest November day since records commenced in 1922 with 43.0 mm, while Carnegie in the Southern Interior observed its wettest November day on record. Showers and thunderstorms on the 24th brought heavy rainfall to central and eastern parts of the SWLD and the southern Goldfields in the 24 hours to 9am on the 25th, with daily falls generally in the 25 mm to 50 mm range. Gibb Rock (Central Wheat Belt) recorded its highest November daily rainfall in 32 years of record during this event, whilst the daily total at Perth Airport of 26.0 mm in a thunderstorm was the third wettest day in November on record at the site, and 20.8 mm fell in 10 minutes from 1813 WST to 1822 WST, which was a one in 20 to 50 year event.

A strong cold front moved across western and central WA and into the southeast of the state on the 28th, with a secondary front moving over the southwest of the state in the afternoon and evening. A cloudband, with areas of rain and widespread showers and thunderstorms, extended over much of western and southern WA, contracting to the southeast of the state during the evening. The passage of an associated rapidly deepening low just off the the WA southwest coast brought very strong winds to southern WA, with isolated thunderstorms in the Southwest and South Coastal districts. Numerous sites experienced their highest wind gusts for November in more than ten years, with maximum gusts in excess of 90 km/h reported across southern WA. Rottnest Island observed the strongest wind gust of 117 km/h at 1146 WST on the 28th. It was a rare occurrence for such a strong storm in late spring and the storm caused traffic congestion in Perth, with one lane closed on the Kwinana Freeway due to waves on the Swan River over-topping the sea wall, airport delays, and extensive power outages with reports of 50,000 houses losing power. Daily rainfall totals in the 24 hours to 9am on the 29th were generally light to moderate for the southern half of the state, grading to 25 mm to 50 mm in parts of the Lower West and Southwest districts. Culford in the Great Southern recorded its highest November daily rainfall in 44 years of record. Squally conditions continued in southern and western parts of the SWLD on the 29th, with isolated thunderstorms in the Southwest and South Coastal districts, mainly during the morning. Severe gusts were observed near the coast in the Lower West, Southwest, and Southeast Coastal districts, the highest being 117 km/h at Cape Leeuwin at 0445 WST on the 29th. Showers persisted over the southwest of the state on the 30th in a westerly flow.

Shower and thunderstorm activity was a consistent feature during November 2012 in the Kimberley and adjacent Pilbara and Interior, with numerous instances of heavy rainfall and severe wind gusts through the month. Warmun observed 102.0 mm in the 24 hours to 9am on the 29th, which is its wettest November day in 82 years of record.

Maximum temperature

Maximum temperatures during November 2012 were above to very much above average in the west Kimberley, Interior, central Pilbara, northeast Gascoyne, Eucla, and South and Southeast Coastal districts. Maximum temperatures were up to 2 °C above normal in an area stretching from the east Pilbara and into the Interior, grading to up to 4 °C above normal in the eastern Interior and Eucla, and up to 5 °C above normal in the western Eucla. Northeastern parts of the SWLD and small areas in the west Pilbara saw below average daytime maxima, with small areas up to 1 °C cooler than normal in these regions. The remainder of the state was generally within 1 °C of the average.

When averaged across the state as a whole, the mean maximum temperature during November 2012 was in the above average range, continuing a run of eight consecutive above average months since April. Mean maximum temperatures were close to, but slightly above, average in the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay) continuing the very warm year to date in the region, with almost all months so far in 2012, apart from February, observing above average mean maxima. The mean maximum temperature for January to November 2012 in the Lower Southwest was 1.1 °C above normal and ranked as equal highest with 2011 since comparable temperature records commenced in 1950. The very much above average year so far is largely due to an above average January, a very much above average autumn (5th warmest), and consistently above average maxima from July to October. This run of "warm" temperatures in the Lower Southwest has persisted for three years, with the Lower Southwest only recording two months below the average, in terms of mean maximum temperature, since October 2009.

Cloud, rainfall, and cool southeasterly winds produced some low maximum temperatures in southern parts of WA to begin November 2012, with temperatures in the low to mid-teens. In contrast, temperatures reached the low forties in the Kimberley, Pilbara, and Interior. Temperatures were well above average in the Eucla and adjacent southern Interior on the 4th in northerly winds ahead of a cold front, causing temperatures to rise to the low forties. The front brought a cool day to inland western parts of the state, with the cool conditions persisting on the 5th as a ridge developed in the wake of a cold front. A warm to hot day was observed in western WA on the 9th as a trough deepened near the west coast and the heat moved through southern WA on the 10th, particularly in the southern Goldfields, Southeast Coastal, and Eucla where temperatures were 8 to 10 °C above normal, with the hot conditions persisting in the southeast of the state on the 11th.

Hot conditions were observed in northern WA on the 13th as a trough lay over the area, with eighteen sites observing temperatures over 40 °C. Mandora in the Kimberley was the hottest location with 44.0 °C. A trough inland of the west coast also resulted in hot maximum temperatures in much of the SWLD, particularly in the Central West and northern Central Wheat Belt where temperatures were in the mid-to-high thirties and well above the November average. The hot weather persisted throughout much of WA on the 14th, away from southern and western parts of the SWLD, west Gascoyne, and coastal Kimberley. Numerous sites in central and northern WA observed temperatures of over 40 °C, with Roebourne the hottest location with 45.1 °C. Hot conditions continued across central and northwestern WA on the 15th, particularly in the central Pilbara where temperatures reached the mid-forties. Roebourne observed the highest temperature in the state with 46.4 °C, which was WA's hottest in November 2012, and also the hottest in WA this year so far. Maxima in excess of 40 °C continued across the Pilbara, inland Kimberley, and Northern Interior on the 16th, particularly in the central Pilbara where temperatures reached the mid-forties. Roebourne Aerodrome observed the highest temperature with 46.0 °C. Temperatures across northern WA in general moderated to the low forties on the 17th, while a hot day was observed in the SWLD, particularly in mostly inland western parts. Carnamah and Mullewa in the Central West both reached 40.1 °C.

Hot conditions were observed throughout much of WA on the 18th, away from the west coast, with temperatures well above normal in the eastern SWLD and Goldfields. Hyden in the Great Southern reached 40.0 °C, while Southern Cross Airfield reached 40.2 °C. Temperatures into the low forties were observed in the Eucla and Interior on the 19th, while a trough near the west coast directed generally easterly winds over the area, resulting in a hot day on the 21st in parts of the western SWLD and adjacent southwest Gascoyne. A hot day was observed in south coast districts on the 27th, with temperatures up to 12 °C above average in northerly winds ahead of a trough. The trough moved through southern WA on the 28th, resulting in a hot day was in the southeast of the state on the 28th where temperatures reached the low forties in the Eucla and eastern Interior. Red Rocks Point observed 41.0 °C, its equal hottest November day in 8 years of record.

Maximum temperatures were well below average throughout much of the SWLD on the 29th, following significant cold fronts on the 28th, with a number of sites only reaching the low to mid-teens. The 15.5 °C recorded at Collie East was its coolest November day in 9 years of record, while Manjimup recorded the coolest day in WA during November 2012 with a maximum of just 13.1 °C.

Minimum temperatures

Minimum temperatures were above to very much above average across an area stretching from the east Pilbara and west Kimberley into the Interior and Eucla, with overnight temperatures up to 3 °C above normal. Above average minima was also experienced in the west Pilbara and southeastern SWLD, while the remainder of the state was generally close to normal.

When averaged across the state as a whole, the mean minimum temperature during November 2012 was above average, continuing the run of above average months since September, after eight consecutive below average months to start the year. The Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay) saw close to, but slightly above average, overnight temperatures in November 2012, continuing a run of above average minima in which only two months since November 2010 have recorded below average overnight temperatures (May 2012 and July 2012).

A cool morning was observed in central western parts of WA on the 5th, with temperatures over 10 °C cooler than normal, in contrast to a warm morning through the Kimberley where temperatures were in the high twenties. A cold morning was observed in southern parts of the SWLD and adjacent Goldfields on the 8th, with a number of sites observing temperatures below 5 °C. A broad heat trough across the Kimberley resulted in a warm morning on the 13th, with daily minima in the low thirties in the north Kimberley. Wyndham observed the highest minimum in the state with 31.0 °C. In contrast to the warm conditions in the north of the state, a high pressure ridge in the Bight brought clear skies and light winds to southern WA, with several sites in the Southwest and Eucla recording daily minima below 5 °C.

After a hot day on the 14th, cloudy conditions as a result of thunderstorms persisted overnight with minimum temperatures in the high twenties to low thirties in the Pilbara and Interior on the 15th. Wittenoom was the warmest location with 31.4 °C, which was also the state's warmest night in November 2012. A warm morning was again observed on the 16th in the Kimberley, Pilbara and Interior, with temperatures in the high twenties to low thirties at a number of sites. A warm night was experienced in large parts of the SWLD and Goldfields on the 22nd, with minimum temperatures in the high teens to low twenties. A warm morning was observed in the Kimberley on the 23rd after a hot day on the 22nd, with temperatures in the high twenties and Wyndham Aerodrome recording a minimum temperature of 30.1 °C.

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