Monthly Weather Review Northern Territory January 2013 Monthly Weather Review Northern Territory January 2013 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 2013 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 25 February 2013. ISSN 1836-392X Cover photograph Shower falling from a developing cumulus near Bradshaw Station. Photograph by Gavin Heathertington-Tait, 23 January 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 January 2013 Overview • Hottest January on record Significant weather • Driest January since 1994 • Longest hottest streak for the Alice Springs An exceptional heat wave in early January An exceptionally extensive and long-lived heat wave January 2013 has made its place in history as the affected large parts of Australia in late December hottest January on record. A record setting heat 2012 and the first weeks of January 2013. Whilst the wave moved through the Alice Springs District. The heat was most extreme and persistent in the central monsoon made only a brief appearance in the north, and southern interior of the continent, most of and the lack of cloud cover and rainfall drove the Australia experienced extreme heat at some stage mean monthly maximum temperature to record during the event. levels. Across the Territory, the January average maximum temperature was the hottest on record. In the southern NT, Alice Springs broke the record for the longest streak of days above 40 °C with 17 days from the 1st to the 17th inclusive (the previous Extremes in January 2013 record streak of 12 days over 40 °C set in 2006). Included in that record hot streak was 11 Hottest day consecutive days, from the 3rd to the 13th inclusive, (Highest daily maximum temperature) where the maximum temperature exceeded 42 °C, 46.7 °C at Walungurru on the 9th also a new record (previous record was 5 days over 46.7 °C at Rabbit Flat on the 25th 42 °C set in 2004). To the south of Alice Springs, Warmest days on average Yulara Aero managed to surpass the 44.0 °C mark 10 (Highest mean daily maximum temperature) days in a row (4th to the 13th inclusive), breaking 42.9 °C at Walungurru their previous record streak of days above 44.0 °C of Coolest days on average 4 days set in 1998. Yulara also experienced 16 (Lowest mean daily maximum temperature) consecutive days above 42 °C from the 2nd to the 31.8 °C at Darwin Harbour 17th inclusive, surpassing the previous record of 11 Coldest day days set in January 2011. (Lowest daily maximum temperature) 25.1 °C at Batchelor Aero on the 18th Hottest January on record for the NT Coldest night The Northern Territory (as well as the entire country) (Lowest daily minimum temperature) had its hottest January on record for mean 13.6 °C at Kulgera on the 30th temperature, reaching 38.9 °C (both night-time and Coolest nights on average daytime temperatures combined) and also its highest (Lowest mean daily minimum temperature) mean maximum temperature on record with 32.0 °C, 21.9 °C at Alice Springs Airport 2.6 °C above the norm. Both existing records for the Warmest nights on average NT were set in 1971. Across the territory, 13 stations (Highest mean daily minimum temperature) recorded their hottest January on record for mean 28.1 °C at Walungurru temperatures. Such records were driven primarily by Warmest night really hot daytime temperatures, in which 12 out of (Highest daily minimum temperature) the 13 stations also recorded their highest mean 32.8 °C at Walungurru on the 22nd maximum temperatures. Gove with a mean Warmest on average overall maximum temperature of 33.6 °C, Tindal with (Highest mean temperature) 36.7 °C and Yulara with 41.3 °C were among the 35.5 °C at Walungurru stations that broke their January record. Darwin Coolest on average overall Airport's mean daytime temperature of 32.8 °C was (Lowest mean temperature) the warmest January since 2002, when daytime 28.8 °C at Central Arnhem Plateau temperatures averaged 33.1 °C. Wettest overall (Highest total rainfall) 452.8 mm at Croker Island Airport Driest overall (Lowest total rainfall) 0 mm at East Dam 0 mm at Wallace Rock Hole Wettest day (Highest daily rainfall) 144.6 mm at Delamere Weapons Range on the 18th Highest wind gust 106 km/h at Cape Wessel on the 20th page 1 Monthly Weather Review Northern Territory January 2013 Synoptic summary Most of the month was defined by a deep and persistent high pressures system that extended across most of the continent, including the NT. The first week of the month saw a shallow surface trough moving slowly across the NT, while a few locations across the central territory received some rain, rainfall totals were quite small. Throughout the month several high pressure centres moved along the sub-tropical ridge. These slow moving, dry and very stable air masses allowed for high temperatures to persist across the central NT for most of the month. Beginning on the 4th, a monsoon trough formed off Australia's north coast, but it remained offshore due to the high pressure over the continent. Even as tropical cyclone Narelle moved south, from the 9th to the 14th, the high pressure over eastern Australia prevented the monsoon trough from moving over the continent. Beginning on the 15th, a surface based low pressure system formed over central Queensland and began moving to the northwest in the ensuing days. At the middle levels of the atmosphere the monsoon trough began shifting south to meet the surface low. This caused the onset of the North Australian Monsoon on the 17th of January. This came about three weeks later than usual, but still within the standard deviation of the the monsoon timing. By the 19th, two low pressure systems had formed over northeastern Australia within the monsoon trough, one over eastern Australia that would eventually become tropical cyclone Oswald and the other over northwestern Australia that would eventually become tropical cyclone Peta. On the 21st tropical cyclone Oswald formed over the Gulf of Carpentaria and then made landfall on the western shores of the Cape York Peninsula. Over the next week ex-tropical cyclone Oswald moved south along the Queensland coast bringing high winds and flooding rains to the area.