Monthly Weather Review South Australia August 2008 Monthly Weather Review South Australia August 2008

Monthly Weather Review South Australia August 2008 Monthly Weather Review South Australia August 2008 The Monthly Weather Review - South Australia is produced twelve times each year by the Australian Bureau of Meteorology's South Australian Climate Services Centre. It is intended to provide a concise but informative overview of the temperatures, rainfall and significant weather events in South Australia for the month. To keep the Monthly Weather Review as timely as possible, much of the information is based on electronic reports. Although every effort is made to ensure the accuracy of these reports, the results can be considered only preliminary until complete quality control procedures have been carried out. Major discrepancies will be noted in later issues. We are keen to ensure that the Monthly Weather Review is appropriate to the needs of its readers. If you have any comments or suggestions, please do not hesitate to contact us: By mail South Australian Regional Office South Australian Climate Services Centre Bureau of Meteorology 25 College Road KENT TOWN SA 5067 AUSTRALIA By telephone (08) 8366 2600 By email [email protected] You may also wish to visit the Bureau's home page, http://www.bom.gov.au. Units of measurement Except where noted, temperature is given in degrees Celsius (°C), rainfall in millimetres (mm), and wind speed in kilometres per hour (km/h). Observation times and periods Each station in South Australia makes its main observation for the day at 9 am local time. At this time, the precipitation over the past 24 hours is determined, and maximum and minimum thermometers are also read and reset. In this publication, the following conventions are used for assigning dates to the observations made: Maximum temperatures are for the 24 hours from 9 am on the date mentioned. They normally occur in the afternoon of that day. Minimum temperatures are for the 24 hours to 9 am on the date mentioned. They normally occur in the early morning of that day. Daily rainfall is for the 24 hours to 9 am on the date mentioned. This means a significant fraction of the rain may have occurred on the previous calendar day. Monthly rainfall is for the period from 9 am on the last day of the previous month to 9 am on the last day of this month. Maximum daily wind gusts are in the 24 hours from midnight to midnight. Climatological values The climatological averages shown in the text and tables are generally long-term means based on observations from all available years of record, which vary widely from site to site. They are not shown for sites with less than 20 years of record, as they cannot then be calculated reliably. Climatological extremes are generally taken from available observations from all available years of record. The number of years can vary substantially from site to site. Copyright © Commonwealth of Australia 2008 This work is copyright. You may download, display, print and reproduce this material in unaltered form only (retaining this notice) for your personal, non-commercial use or use within your organisation. Apart from any use as permitted under the Copyright Act 1968, all other rights are reserved. Requests and inquiries concerning reproduction and rights should be addressed to Commonwealth Copyright Administration, Attorney General’s Department, Robert Garran Offices, National Circuit, Barton ACT 2600 or posted at http://www.ag.gov.au/cca. Product code IDCKGC13R1. This version prepared on 12 March 2009, revising an issue prepared on 3 October 2008. ISSN not assigned yet Cover photograph Wave clouds over the Adelaide Hills. Photograph by Bob Schahinger, 30 November 2002. Used with permission. Monthly Weather Review South Australia August 2008 Overview • Rainfall was generally near average Significant weather • August temperatures were generally below average Severe Thunderstorms Rainfall was generally near average, tending below 1 August 2008 average in the southern Pastoral areas. Some A line of heavy showers and thunderstorms moved locations around the Lower Lakes and Coorong, as northeast across Adelaide during the morning of 1 well as the far north of the state had August totals in August, producing small hail and squally west to the top 10 percent of records. Temperatures were southwest winds, including a wind gust to 91 km/h at generally below average across most of the State. Edinburgh Airport. A second line of convection Some locations had record lowest daily temperature moved through the Murraylands in the early records or had coldest August maximum or minimum afternoon producing a 91 km/h wind gust at temperatures on record. Lameroo. Extremes in August 2008 Severe Winds 6 August 2008 Hottest day A sharp low pressure trough, with an embedded (Highest daily maximum temperature) meso-low affected the Central district on 6 August, 29.5 °C at Oodnadatta Airport on the 29th with a burst of near gale force, squally southwest to Warmest days on average southerly winds occurring on the western side of the (Highest mean daily maximum temperature) trough and with the meso-low. One severe event 19.7 °C at Moomba Airport was observed - a southerly squall with a gust to 95 19.7 °C at Oodnadatta Airport km/h at Cape Willoughby on Kangaroo Island. Coolest days on average (Lowest mean daily maximum temperature) 7.3 °C at Mount Lofty Coldest day (Lowest daily maximum temperature) 4.0 °C at Mount Lofty on the 10th Coldest night (Lowest daily minimum temperature) -5.0 °C at Gluepot Reserve (Gluepot) on the 22nd Coolest nights on average (Lowest mean daily minimum temperature) 1.4 °C at Yongala Warmest nights on average (Highest mean daily minimum temperature) 10.3 °C at Neptune Island Warmest night (Highest daily minimum temperature) 17.6 °C at Arkaroola on the 30th Wettest overall (Highest total rainfall) 253.0 mm at Inglewood Alert Driest overall (Lowest total rainfall) 0.5 mm at Moomba (Tantanna) Wettest day (Highest daily rainfall) 131.8 mm at Inglewood Alert on the 13th Highest wind gust 120 km/h at Renmark Aero on the 23rd page 1 Monthly Weather Review South Australia August 2008 Synoptic summary Shower and drizzle activity over the agricultural region contracted southeastwards and cleared by During the first week of the month, the subtropical early on Monday 25 th August. There was also a brief ridge of high pressure lay across central Australia. spell of shower activity over the southern coast and There was also another ridge that appeared ranges with the cold front. intermittently to the east and south of Tasmania. A cloud band affected the interior on Sunday 24 th Lows and associated cold fronts tended to move but conditions remained fine. northeastwards towards southeastern Australia and fill, before redevelopment in the Tasman Sea. On Friday 29 th and Saturday 30 th a trough over the Frontal/low passages affected southeastern South Great Australian Bight deepened into a low pressure Australia on Monday 4 th , Wednesday 6 th , Friday 8 system that slipped southeastwards. The trough and th , and Saturday 9 th August. Shower activity was low were accompanied by a couple of cloud bands. generally confined to the agricultural area in a moist, Rain commenced overnight 29 th /30 th and affected onshore airstream. the entire State during the 30 th with isolated thunderstorms. Into the second week of the month, the subtropical ridge of high pressure drifted slightly southwards As the subtropical ridge of high pressure across South Australia and linked to strong high re-established across the interior of the State on pressure centres near southern Western Australia. Sunday 31 st , showers contracted to the southeast. A cold front affected southeastern South Australia on Tuesday 12 th August. Shower activity was confined to the agricultural area in a moist, onshore airstream. A cloud band transited the interior on the 12 th but conditions remained fine. The middle part of the month was dominated by a slow-moving high pressure centre over the Great Australian Bight. This system eventually drifted northeastwards and weakened across South Australia. Another high centre progressed eastwards to the south of Western Australia and attained a near-extreme maximum value of mean sea level pressure (analysed at 1048hPa) during Thursday 21 st . The retreat of the former high into the southern interior of the State permitted westerly flow to temporarily amplify across the agricultural area in advance of a trough/cold frontal passage late on Wednesday 20 th and during Thursday 21 st August. A low pressure system subsequently formed in the Tasman Sea. Shower activity was confined to the agricultural area up to Monday 18 th August in a moist, onshore airstream, but resumed from the evening of the 20 th . Cloud bands affected the interior on Thursday 14 th and Sunday 17 th , but conditions remained fine. Despite the near-extreme value of high pressure on the 21st, the high pressure centre weakened and progressed steadily eastwards across southern Australia. This was replaced by another high centre over the Great Australian Bight on Tuesday 26 th , that subsequently slipped southeastwards towards Tasmania. A weak cold front affected the southeast of the State on Tuesday 26 th . page 2 Monthly Weather Review South Australia August 2008 Daily mean sea level pressure analyses 1 August 2008 2 August 2008 3 August 2008 4 August 2008 5 August 2008 6 August 2008 7 August 2008 8 August 2008 9 August 2008 10 August 2008 11 August 2008 12 August 2008 13 August 2008 14 August 2008 15 August 2008 16 August 2008 17 August 2008 18 August 2008 page 3 Monthly Weather Review South Australia August 2008 19 August 2008 20 August 2008 21 August 2008 22 August 2008 23 August 2008 24 August 2008 25 August 2008 26 August 2008 27 August 2008 28 August 2008 29 August 2008 30 August 2008 31 August 2008 page 4 Monthly Weather Review South Australia August 2008 Temperatures August temperatures were generally below average across most of the State.

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