Thursday, 1 December 2011 - Monthly Climate Summary for Western Australia - Product code IDCKGC21R0

Western Australia in November 2011: Fifth wettest November on record

• Rainfall: 5th wettest for WA; 10th wettest for southwest WA
• Maximum temperature: Below average for WA; above average for southwest WA
• Minimum temperature: Below average for WA; above average for southwest WA.

Details Extremes Records Summaries Important notes the top

Rainfall

November 2011 rainfall was above to very much above average for most of WA and a number of sites in the Kimberley, Pilbara, Gascoyne, Central Wheat Belt, Great Southern, Southeast Coastal, and Goldfields registered their wettest November on record. Below average rainfall was mainly confined to the Eucla, and small areas of the southern Goldfields, northern Central West, and west Kimberley (see November 2011 rainfall totals & deciles ).

When averaged across the state, November 2011 was the fifth wettest November on record for WA (comparable records commenced in 1900), whilst November rainfall for the Lower Southwest (southwest a line from Jurien Bay to Bremer Bay) ranked as tenth wettest on record.

November 2011 started with a surface low over the west Pilbara that extending to the middle levels of the atmosphere and brought widespread rainfall to northern and central WA on the 1st and 2nd. Heavy rainfall with daily falls over 50 mm were recorded in a number of locations in the Pilbara, Gascoyne and northern Goldfields, and some sites, particularly in the Pilbara, also experienced their wettest November day on record . Cossack on the Pilbara coast had its wettest November day in 49 years of record with a daily total of 97.0 mm on the 2nd, which was also the highest daily rainfall of the month for WA. The surface trough over the west of the state extended southward and combined with an approaching middle level disturbance on the 3rd and 4th to produce widespread rainfall and thunderstorms across the southern half of WA, with daily falls over 40 mm registered at numerous sites in the Central Wheat Belt, Great Southern, South and Southeast Coastal on the 4th. Several daily rainfall records for November were broken in these districts and a number of these sites have over 100 years of rainfall recording history. Heavy storms over the central Kimberley on the afternoon of the 16th brought significant rainfall to Gibb River as 71.0 mm was recorded in the 24 hours to 9am on the 17th, a new November daily rainfall record for the site. A surface trough over the Pilbara and near the west coast, along with a supporting middle level feature brought significant thunderstorm activity to central parts of the state on the 20th and produced a number of daily falls over 50 mm in the northeast Gascoyne and a few November daily rainfall records in the 24 hours to 9am on the 21st.

Maximum temperature

November 2011 maximum temperatures were above to very much above average in the southern coastal areas, and parts of the west Kimberley and west Gascoyne, with mean maxima up to 3°C above normal in the eastern Eucla and Shark Bay region of the Gascoyne. However, below average maxima were observed across much of WA, in most of the Kimberley, central and east Pilbara, Interior, inland Gascoyne, and northern Goldfields, with daytime temperatures up to 4 °C below normal in the east Kimberley and northern Interior (see November 2011 mean maximum temperature deciles & anomaly maps).

When averaged across the state, the maximum temperature during November 2011 was below average. In contrast, the Lower Southwest experienced above average daytime temperatures during November 201. This continues the trend of above average maximum temperatures in the Lower Southwest for all months this year, and consequently the January to November period has been the warmest first 11 months of the year for the region since comparable records commenced in 1950.

Western and southern parts of the state experienced a few unseasonally hot days in the latter part of the month when a high pressure system moved slowly south of the state directing hot and dry northeasterly winds over the region. Daily maxima reached the mid-to-high 30s near the west coast and southern coastal strips, and were more than 10 °C above the long-term monthly average.

Minimum temperature

November 2011 mean minimum temperatures were above to very much above average in most of the Southwest Land Division (SWLD), eastern Eucla, west Gascoyne, and coastal Pilbara, with means up to 3°C above normal near the eastern Eucla coast. Below to very much below average mean minima were experienced in most of the Kimberley, in the northern and central Interior, east Pilbara and inland Gascoyne, with means up to 3 °C cooler than normal in the southeast Kimberley and northeast Interior (see November 2011 minimum temperature deciles & anomaly maps).

November 2011 was below average in terms of mean minimum temperature when averaged across the state, whilst the Lower Southwest was above average. Mean minimum temperatures have been consistent with mean maximum temperatures in the Lower Southwest, and again all 11 months of 2011 have been above average in terms of mean minima, and thus the Lower Southwest has recorded its warmest January to November period on record for overnight temperatures.

Although no individual minimum temperature records were broken during the month, many locations in the Central West and Lower West endured uncomfortable warm nights on the 23rd and 24th with daily minima in low 20s.

Other Phenomena

Severe thunderstorms developed in the SWLD in the afternoon on the 3rd with very heavy rainfall reported. Roof damage was reported in Beverley in the Central Wheat Belt, whilst local flooding and property damage was reported from Bokal in the Southwest, and minor roof damage and flooding was also reported in Albany in the South Coastal district.

tails Extremes Records Summaries Important notes the top

Details Extremes Records Summaries Important notes the top

Details Extremes Records Summaries Important notes the top