Monthly Weather Review Northern Territory October 2012 Monthly Weather Review Northern Territory October 2012 The Monthly Weather Review - Northern Territory is produced twelve times each year by the Australian Bureau of Meteorology's Northern Territory Climate Services Centre. It is intended to provide a concise but informative overview of the temperatures, rainfall and significant weather events in Northern Territory 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 Northern Territory Climate Services Centre Bureau of Meteorology PO Box 40050 Casuarina NT 0811 AUSTRALIA By telephone (08) 8920 3813 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 Northern Territory 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. Mean temperatures are the average of the daily maximum and daily minimum temperatures. 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 10 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 2012 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 IDCKGC22R1. Prepared on 23 November 2012. ISSN 1836-392X Cover photograph A towering cumulus out to sea off Black Point. Photograph by Gavin Heathertington-Tait, 27 Octoboer 2008. 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 Northern Territory October 2012 Overview October heralds the start of the wet season across Significant weather northern Australia and the beginning of the peak fire First taste of severe thunderstorms in weather season for central and southern parts of the Darwin Northern Territory. Strengthening northerly winds ahead of approaching cold fronts or troughs, On the early hours of Ocotber 28, thunderstorms represent a classic weather situation for the month with heavy rain formed over Darwin with the of October, however, October saw below average heaviest falls occurring in the northern suburbs. In rainfall across most of the Top End with some very just a couple of hours, 110.8 mm of rain were hot days but relative cool nights throughout. reported at Leanyer with reported flash flooding in the suburb of Lyons. The rainfall was a classic example of very localised heavy rainfall over Darwin Extremes in October 2012 as both the northern suburbs and the region from Humpty Doo to the Cox Peninsula received more Hottest day than 40 mm while the Airport and the immidiate (Highest daily maximum temperature) suburbs to the south, including the city, missed out 42.8 °C at Rabbit Flat on the 10th (Darwin Airport recorded only 6 mm for the day). Warmest days on average (Highest mean daily maximum temperature) October bushfires 39.2 °C at Bradshaw Fires near Lambells Lagoon in Darwin's rural area Coolest days on average required aerial suppression techniques on the 3 (Lowest mean daily maximum temperature) October. The fires, managed to damage a number of 30.5 °C at McCluer Island sheds, trucks and other vehicles. Later in the month Coldest day (14th) and again near Lambells Lagoon, aerial (Lowest daily maximum temperature) suppression techniques were required to control 20.4 °C at Arltunga on the 26th fires that damaged an estimated $57,8000 of mango Coldest night trees. Hot, dry easterly winds due to a high pressure (Lowest daily minimum temperature) system over NSW produced Grassland Fire Danger 4.0 °C at Alice Springs Airport on the 13th Index values in the very high range over the Top End Coolest nights on average and Darwin rural area. (Lowest mean daily minimum temperature) 13.3 °C at Arltunga Central Australia feels the heat Warmest nights on average On October 24th at 14:30 hours, the temperature at (Highest mean daily minimum temperature) the Alice Springs Airport reached 41.7 °C, equaling 26.3 °C at McCluer Island the previous hottest Ocotber day record set on 18 Warmest night October 2002. This came at the end of a hot spell for (Highest daily minimum temperature) the Alice Springs which saw 9 consecutive days 28.0 °C at Timber Creek on the 28th above 37 °C, a new record for an October hot spell of Warmest on average overall that magnitude. (Highest mean temperature) 31.7 °C at Bradshaw Coolest on average overall (Lowest mean temperature) 22.6 °C at Arltunga Wettest overall (Highest total rainfall) 166.4 mm at Pirlangimpi Wettest day (Highest daily rainfall) 110.8 mm at Leanyer on the 28th Highest wind gust 87 km/h at Walungurru on the 24th page 1 Monthly Weather Review Northern Territory October 2012 Synoptic summary The month started with a strong high pressure system over central Australia directing dry but cool winds across most of the Northern Territory. These winds, along with clear skies led to below average temperatures across most of the Alice Springs District and Barkly for a couple of days. A slow moving trough gradually pushed into the Territory from Western Australia bringing hot northerly winds across the southern Northern Territory ahead of the trough. The trough eventually pushed east on the 10th bringing a cool relief to the Alice Springs District. From the 11th to the 14th another relatively strong high pressure system kept skies clear over most of the Northern Territory, particularly over the south. From the 14th to the to the 24th, a series of weak troughs skirted the southern parts of the Northern Territory but these were too week to bring any associated rainfall. On the 24th, a strong, fast moving trough swept through central Australia bringing very hot northerly winds ahead of a gusty but cooler change. The same system, brough some of the heaviest falls of the month to the base of the Top End as the cool air mass behind the trough merged with the warm and moist air mass to the north. From the 25th until the end of the month a slow moving ridge dominated most of the continent leading to mostly sunny conditions, cool nights and warm days. page 2 Monthly Weather Review Northern Territory October 2012 Daily mean sea level pressure analyses 1 October 2012 2 October 2012 3 October 2012 4 October 2012 5 October 2012 6 October 2012 7 October 2012 8 October 2012 9 October 2012 10 October 2012 11 October 2012 12 October 2012 13 October 2012 14 October 2012 15 October 2012 16 October 2012 17 October 2012 18 October 2012 page 3 Monthly Weather Review Northern Territory October 2012 19 October 2012 20 October 2012 21 October 2012 22 October 2012 23 October 2012 24 October 2012 25 October 2012 26 October 2012 27 October 2012 28 October 2012 29 October 2012 30 October 2012 31 October 2012 page 4 Monthly Weather Review Northern Territory October 2012 Temperatures During Ocotber, the overall mean temperature (average of daily maximum and daily minimum temperature) was above average across the far southern NT and the Tiwi Islands while below average mean temperatures were only observed in the far southern Darwin - Daly and Victoria River districs. Everywhere else across the Territory was average with a mean area averaged temperature of 27.3 °C. The warmest on average was Bradshaw with 31.7 °C, followed by Timber Creek with 31.1 °C and then by Jabiru Airport and Katherine Country Club with 30.9 °C.