Monthly Weather Review South Australia April 2010 Monthly Weather Review South Australia April 2010
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Monthly Weather Review South Australia April 2010 Monthly Weather Review South Australia April 2010 The Monthly Weather Review - South Australia is produced twelve times each year by the Australian Bureau of Meteorology's South Australia 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 Australia Climate Services Centre Bureau of Meteorology PO Box 421 Kent Town SA 5071 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 2010 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. Prepared on 13 May 2010. ISSN 1836-3024 Cover photograph Power mobile - Mt Barry Station. Photograph by Bob Beggs, 27 April 2010. Used with permission. If you have a photo you think would make a good cover for the Monthly Weather Review, please contact us at the address above. Monthly Weather Review South Australia April 2010 Overview • Above to well above average rainfall over the Significant weather pastoral districts, and over parts of the southeast, with record April rainfall in the southeast of the Severe Thunderstorms Northwest Pastoral District. 6 April 2010 • Warmer than average across the state, with a Thunderstorms during the afternoon produced warmer than average year so far. hailstones and flash flooding at Taylorville, north of • Record warm April minimums over South Waikerie and 25 mm in 20 minutes at Mindarie. Australian agricultural areas. Earlier during the day, 60 mm occurred at Crafers and 45 mm at Adelaide Airport. Extremes in April 2010 8−9 April 2010 Hottest day Thunderstorms across the north of the state during (Highest daily maximum temperature) the evening of the 8 April and the early hours of the 35.9 °C at Moomba Airport on the 7th 9 April produced rainfall gaugings to 9 am of 124 mm Warmest days on average at Roxby Downs Station, 86 mm at Olympic Dam, (Highest mean daily maximum temperature) 85 mm at Andamooka and 67 mm at Leigh Creek, 29.2 °C at Moomba Airport including 43 mm in one hour. 29.2 °C at Oodnadatta Airport Coolest days on average 20 April 2010 (Lowest mean daily maximum temperature) Thunderstorms forming in a moist and unstable 18.3 °C at Mount Lofty airmass across northern districts produced heavy Coldest day rainfall and flash flooding. Significant rainfall (Lowest daily maximum temperature) gaugings across the pastoral districts included 38 mm 12.2 °C at Mount Lofty on the 28th at Andamooka, with 36 mm falling in 36 minutes. Coldest night Olympic Dam received 35 mm of rainfall with (Lowest daily minimum temperature) 33.6 mm falling in one hour. Maynards Well 2.0 °C at Yongala on the 28th recorded a total of 42 mm of rain, with 32 mm falling Coolest nights on average in 35 minutes. (Lowest mean daily minimum temperature) 9.3 °C at Yongala Significant rainfall gaugings across the Flinders and Mid North districts included 32 mm in 30 minutes at Warmest nights on average (Highest mean daily minimum temperature) Tarlee, falling as a mixture of rain and some hail. 16.9 °C at Moomba Airport Wilmington reported 55 mm in the 24 hours to 9 am on 21 April. It is assumed most of this would have Warmest night (Highest daily minimum temperature) fallen in a short time during the afternoon of the 20 23.4 °C at Marla Police Station on the 7th April. Wettest overall (Highest total rainfall) 156.0 mm at Andamooka Driest overall (Lowest total rainfall) 1.8 mm at Minnipa DPI Wettest day (Highest daily rainfall) 86.0 mm at Roxby Downs (Olympic Dam Aerodrome) on the 9th Highest wind gust 85 km/h at Cape Jaffa (The Limestone) on the 6th page 1 Monthly Weather Review South Australia April 2010 Synoptic summary southern agricultural area on the 27th, associated with a ridge pushing in over South Australia behind The month started with fine conditions throughout, the front and directing a cool south to southwest air apart from isolated light showers in the Lower South stream across the state. East associated with the passage of a weak front on the 1st. A high south of the Great Australian Bight On the 28th, a moist west to northwest air stream continued to track slowly east, maintaining fine brought isolated showers to the southern conditions through to the 3rd. agricultural area as a high moved into the west. Isolated showers and thunderstorms were reported Showers were scattered in the Lower South East due in the far west on the 4th, ahead of a trough to a front passing to the south. These showers approaching from the west. This activity extended persisted over the agricultural area on the 29th with further into western and northern parts of the state the high maintaining a moist southwest to southeast on the 5th, and into central and eastern districts on flow. Fine conditions prevailed in the north, and the 6th as the trough moved east. extended throughout on the 30th as the high continued slowly east. On the 7th, an extensive area of cloud across the southern half of the State kept temperatures near average with isolated light showers. In the north, clearer skies and warmer temperatures resulted in isolated showers and thunderstorms in the afternoon. An upper level trough and weak surface low brought rain and isolated thunderstorms into the west of the state on the 8th, extending into central and eastern parts by the 9th. Showers continued across the state on the 10th and 11th, associated with a moist southwest to northwest air stream and the passage of a front across the south. These showers contracted to the east on the 12th ahead of a high south of the Great Australian Bight, and cleared the state on the 13th as the high moved slowly east. Fine conditions prevailed on the 14th and 15th as the high continued to move slowly east, apart from isolated light showers about the Lower South East on the 14th. A low pressure trough over Western Australia, accompanied by an upper disturbance produced isolated showers from middle level cloud in the west of the State on the 16th. This cloud and associated showers extended eastwards on the 17th, before contracting to the southeast on the 18th with the low and upper trough stalling near Kangaroo Island. Moisture combined with the slow moving low resulted in isolated showers and thunderstorms over eastern parts of the State on the 19th, 20th and 21st. Isolated thunderstorms were also observed about the western border on the 20th. Conditions were fine throughout on the 22nd ahead of a pre-fontal trough moving across the Great Australian Bight. On the 23rd, this trough and associated cloud band brought isolated showers to southern parts of the State ahead of a front south of the Bight.