Monthly Weather Review Western Australia March 2009 Monthly Weather Review Western Australia March 2009 The Monthly Weather Review - Western Australia is produced twelve times each year by the Australian Bureau of Meteorology's Western Australia Climate Services Centre. It is intended to provide a concise but informative overview of the temperatures, rainfall and significant weather events in Western 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 Western Australia Climate Services Centre Bureau of Meteorology PO Box 1370 WEST PERTH WA 6872 AUSTRALIA By telephone (08) 9263 2222 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 Western 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 30 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 2009 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 IDCKGC21R1. Prepared on 24 April 2009. ISSN 1836-3032 Cover photograph Cumulus clouds over Mitchell Plateau near Port Warrander, Admiralty Gulf, North Kimberley, WA. Photograph by Kerrie Goodchild, 28 January 2003. Copyright © 2008 Kerrie Goodchild. 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 Western Australia March 2009 Overview • Monthly rainfall near average. Extremes in March 2009 • Mean daily maximum temperature near average. • Mean daily minimum temperature near average. Hottest day March 2009 in Western Australia saw above average (Highest daily maximum temperature) rainfall in the east Pilbara, east Gascoyne, northern 44.5 °C at Onslow on the 28th Goldfields and western Interior mostly due to heavy Warmest days on average rainfall from a tropical low at the beginning of the (Highest mean daily maximum temperature) month that caused flooding in these regions. In 39.5 °C at Emu Creek Station contrast, the north and east Kimberley, west Pilbara Coolest days on average and parts of the central and west Gascoyne received (Lowest mean daily maximum temperature) much lower than normal rainfall for March. Two 22.0 °C at Albany tropical cyclones formed in the WA region, however Coldest day neither affected the WA coast. (Lowest daily maximum temperature) Averaged over WA as a whole, both mean daily 15.0 °C at Mount Barker on the 31st maximum and minimum temperatures for March Coldest night 2009 were near average. In terms of mean maximum (Lowest daily minimum temperature) temperatures, most southern and central parts of 2.5 °C at Wandering on the 3rd WA saw near average conditions, whilst much of the Coolest nights on average Kimberley and northern Interior experienced higher (Lowest mean daily minimum temperature) than normal mean maxima. Mean minima were close 10.1 °C at Jarrahwood to average for much of the state although some Warmest nights on average parts of western WA saw below average minima, and (Highest mean daily minimum temperature) parts of the northern Interior and southern 27.3 °C at Troughton Island Kimberley recorded above average minima. (On the WA mainland) 25.6 °C at Broome Airport Warmest night (Highest daily minimum temperature) 29.8 °C at Wittenoom on the 16th Wettest overall (Highest total rainfall) 234.0 mm at Bonney Downs Wettest day (Highest daily rainfall) 137.0 mm at Marble Bar (DoW) on the 1st Highest wind gust 104 km/h at Wyndham Aero on the 3rd page 1 Monthly Weather Review Western Australia March 2009 Significant weather Synoptic summary Tropical Cyclones A tropical low crossed the Pilbara coast near Port An Indian Ocean low formed in the monsoon trough Hedland at 2100 WDT on the 28th of February. The in late February and was named TC Gabrielle at 2100 low moved southeast through central parts of the WDT on 2nd March, approximately 370 km state on the 1st and 2nd of March, as an associated south-southeast of Christmas Island. However, upon trough along the west coast moved inland. Showers reanalysis the system was deemed not to have and thunderstorms were observed over most of WA reached cyclone intensity, though gales were during this period while heavy rain caused some apparent in some sectors for many days as the low flooding in the east Pilbara, east Gascoyne and meandered to the south and southwest of Christmas adjacent northern Goldfields and Interior. A cold Island, and shipping warnings continued until early front moved through southern districts on the 2nd on the 6th. There was no known impact from this bringing some showers, before moving eastwards low. along the south coast and exiting the state on the 3rd as a strong ridge extended over the southern half A tropical low passed westward north of Australia of WA. Showers and thunderstorms were confined to and close to Timor before heading into the Indian the Pilbara, northern Interior and Kimberley with the Ocean. The low intensified and was named TC Ilsa remainder of WA fine apart from some lingering early on the 18th, over 800 km north of Exmouth. showers along the south coast. On the 4th and 5th a Ilsa was a small and intense cyclone, reaching high pressure system moved south of WA. Showers category 3 intensity, that moved in a general and thunderstorms were observed in the Pilbara, west-southwest direction eventually weakening near Kimberley and northern Interior on the 4th, 90E by the 24th. There were no known impacts. becoming more isolated on the 5th. In the south, fine conditions prevailed apart from some light showers Severe Thunderstorms and drizzle mainly confined to the Eucla. On the 30th, a thunderstorm at Tom Price in the A weak cold front brushed past the Southeast Pilbara produced 100 mm of rain and caused Coastal and Eucla districts on the 6th causing a few localised flooding. Three calls for assistance were light showers, while in the north some very isolated received by FESA. The official Tom Price observation showers and storms in the east Pilbara cleared in the site recorded 69.2 mm in the 24hrs to 9 am on the early morning, and isolated afternoon and evening 31st. showers and storms developed in the west Pilbara. On the 7th, a high pressure system moved south of Heavy Rainfall WA whilst in the north, a surface trough lay through A tropical low, which developed in the Gulf of the Pilbara and Kimberley. Isolated showers and Carpentaria on the 20th of February and tracked thunderstorms were reported in the Kimberley and westward along the NT Top End coast, north of the near the Pilbara coast, whilst isolated showers Kimberley and roughly parallel with the WA coast, persisted near the Eucla coast. A weak mid-level began to move toward the Pilbara coast on the 28th. disturbance moved over the South West Land The low crossed the Pilbara coast at 21:00 WDT near Division (SWLD) on the 8th before moving through Port Hedland. Heavy rain occurred from the 28th of southeast parts of WA on the 9th. Showers persisted February to early on the 2nd of March to cause in the Eucla during this period, whilst in the north flooding from the east Pilbara extending to the isolated showers and thunderstorms occurred in the eastern Gascoyne and adjacent northern Goldfields Kimberley and far west Pilbara on the 8th, but were and Interior.