BoM track map for Tropical Cyclone Owen issued about 19.00 CST Thursday 13 December. Owen's actual westbound track is shown as a black line with its forecast return eastbound track as a grey line. As Owen has moved back across the Gulf it has followed the forecast track closely, but had not strengthened above Category 3 as of 22.00 EST Friday 14th. BoM.

 QLD: TC Owen strengthens while lurking in the Gulf
Fri 14 Dec 2018

Category 3 Tropical Cyclone Owen had weakened into a Tropical Low before it left the Coral Sea on Monday 10^th. It crossed Cape York Peninsula into the Gulf of Carpentaria the same day then redeveloped into a Category 1 Tropical Cyclone late on Tuesday 11^th, was upgraded to Category 2 early on Wednesday afternoon 12^th as it moved W into NT waters, then further strengthened to Category 3 late Thursday morning 13^th. It then became nearly stationary on the NT coast between Port Roper and Port McArthur.

After lingering for a few hours, Owen began to return eastwards close to its westbound track. The cyclone is a small but intense system which has shown only a poorly-defined or ragged eye on Friday 14^th, or a dimple in upper clouds above the low level circulation centre, according to BoM and Joint Typhoon Warning Centre (JTWC) technical notes. This tweet by Kerrin Binnie of Himawari satellite imagery is fairly typical of Owen's disorganised state. Tracking it has been greatly helped by nearby radars at Gove and Mornington Island and ASCAT scatterometer satellite data which shows its detailed wind field. Owen is being steered east between an upper low that is giving foul weather to much of SE Australia and a ridge near the equator. The system has no upper shear to distort its vertical shape and reduce its efficiency, and is moving over Gulf waters that are a cyclone-friendly 30 to 31°. At 22.00 EST 14^th, Owen's central pressure was estimated at 975hPa. BoM expects Owen to maintain intensity and make landfall between the Gilbert River mouth and Pormpuraaw in the very early hours of Saturday with winds averaging 120km/h gusting to 165km/h.

After that, a ridge to the east of QLD will steer the weakening cyclone to the SE, close to the coast rather as shown in this ABC animation. Increasing vertical shear and interaction with land will weaken the system, though to what extent depends partly on whether Owen moves into the Coral Sea and redevelops, which BoM gives a 20 to 50% chance of happening. Whatever the outcome, current BoM thinking is that "there is going to be the increased risk of heavy to locally intense rainfall and damaging to locally destructive winds in areas of northern and central Queensland over the coming days."

Wed 12 Dec 2018 NT: Hot day and night set records tumbling. A long heatwave event across the NT entered its second week today 12^th with widespread new December and all-time records set for both high minima and maximum temperatures. Most of the high minima were in the Top End, where a trough lying across the southern Top End from Tropical Cyclone Owen in the Gulf has introduced humid Gulf air and instability that brought many thunderstorms with heavy falls in the NE of the Territory. Most of the high maxima were in the southern Territory.

Tue 11 Dec 2018 QLD: Ex-Tropical Cyclone Owen brings heavy rain, some wind to FNQ. Owen, the first Tropical Cyclone of the season to affect Australia, degenerated into a Tropical Low on Tuesday 4 December when it was about 1000km NE of Cairns [NASA-NOAA]. Since then it has meandered around in the Coral Sea, finally making landfall at about 03.00 on Monday 10^th near Port Douglas.

The circulation was quite clear on radar as it approached the coast, dropping over 100mm at most places between the Daintree and Ingham between 09.00 Sunday 9^th and 05.00 Monday 10^th. Some mountain areas received around 300mm in this time with a few river gauges indicating minor flooding on Monday morning. Intense rain was recorded to the south of the centre, including 184mm at Flaggy Creek, NW of Kuranda, and 106mm at Strathdickie near Proserpine in 6 hours to 03.00 10^th as the Low made landfall. Bilyana, between Tully and Cardwell, recorded 92mm in 60 minutes just before midnight. Some wind damage was caused, with a top measured gust of 87km/h at Cairns Airport and reports of up to 100km/h off Port Douglas [ABC]. Trees were brought down at Yarrabah on the headland east of Cairns.

Heavy rain continued to be drawn across the coast as Ex-TC Owen moved across the base of Cape York Peninsula [Andrew Miskelly]. In the 2½ days (60 hours) to 21.00 today 11^th, over a dozen of the Bureau's flood warning rain gauges from Ingham to Cairns, mostly in mountain areas behind the coast, recorded over 300mm, with the highest fall 517mm at Kirama Range Alert, SW of Tully. Other high totals were the tide alert gauge in Cardwell 465mm, Abergowrie Bridge Alert 402mm and Bilyana 370mm. A number of gauges with about 20-year histories had their heaviest December 24-hour totals on record to 09.00 10^th

Note that, as of 21.30 EDT Wednesday, Owen has redeveloped into a Category 2 Tropical Cyclone in the Gulf of Carpentaria, and is expected to do a u-turn overnight into Thursday before strengthening to Category 3, then weaken as it again crosses Cape York Peninsula, then potentially redevelop again after it arrives in the Coral Sea. Use the BoM Tropical Cyclone Warning page to keep track of it.

Wed 12 Dec 2018 NT: Darwin sweats through back-to-back record hot nights. If you didn't have air conditioning, sleep would have been fitful at best through the night of Monday/Tuesday 10^th/11^th. The minimum temperature only just scraped below 30° to 29.7 equalling the two hottest nights in 79 years of observations at Darwin Airport - 25 November 1987 and 17 December 2014. Relative humidity sat stubbornly between 70 and 80% all night.

Last night, Tuesday/Wednesday 11^th/12^th was worse - the temperature didn't get below 30.0° and humidity was similar to the previous night. 30.0° is the new all-time record warm night for Darwin Airport. However, the old Post Office site, which ran from 1885 until the Airport took over in 1942, had a warmer night. Its all-time record was 30.7° on 18 January 1928. That was long before air conditioning.

Tue 11 Dec 2018 WA: Another remarkable thunderstorm wind gust. Forrest is a small settlement (population 18) on the Nullarbor Plain just west of the WA/SA border. It is a station on the longest stretch of straight railway in the world and also a fuelling point for small aircraft at the airstrip. On Tuesday 11^th between 16.15 and 16.45 it had a storm that delivered a temperature drop of 14.7° and a new all-time record wind gust of 130km/h in the middle of a downpour that gave 23.6mm in 10 minutes of which 13.0mm fell in 4 minutes to 16.37, the time of the gust. 44.0mm had fallen by the time the rain stopped, nearly twice the amount Forrest averages in a whole December.

 Unprecedented heatwave makes lap of the continent
Sat 8 Dec 2018

A heatwave that has set record high temperatures at many places with long weather histories has been lapping the continent over the past two weeks. Beginning along the QLD coast during the last week of November, the area of extreme heat moved west to reach the WA Kimberley last Thursday 6^th before some was carried SE in a northwesterly stream to give record warm nights in parts of SA, VIC and TAS on Friday 7^th and Saturday 8^th.

In QLD, extreme heatwave conditions occurred along the coast from Rockhampton almost to the tip of the Cape York Peninsula between 24 and 29 November with many locations with long histories of weather observation recording their November and, in some cases, their all-time highest temperatures. In a media release on 30 November, Bureau of Meteorology State Manager for Queensland, Bruce Gunn, said "The severity of conditions is reflected both in the number of records broken and number of fires, many of which [were then] still burning." The QLD bushfires were covered briefly in an earlier story; this article deals with the exceptional number of records set.

• Weather records at Cairns Airport go back to 1942 and before that observations were made at the Post Office back to 1889. At both locations, the previous highest November temperature was 37.2° in 1971 and 1900 respectively. While temperatures at different locations can't strictly be compared, Cairns Airport had five consecutive days that broke the old November record (26 to 30 November). Three of them, 42.6, 42.1 and 40.5° on 26, 27 and 28 November, broke or equalled the previous all-time record of 40.5 at the Airport, but not the 43.2 figure from 1923 at the old PO site. However, the Cairns Racecourse maximum of 43.6° on 26 November, repeated the next day for good measure, was the highest temperature ever recorded in the city area.
• Mackay is in a similar situation with weather observations made at the Post Office from 1908 and the Airport from 1950. Every day from 24 to 28 November had a higher maximum temperature than the previous November record of 36.6° at the Airport in 2008 with the hottest day, 39.7 on the 26^th beating the previous all-time record of 38.5 set in 1955, also at the Airport.
• Other stations with at least a half-century of observations to set all-time high maximum temperature records were Low Isles Lighthouse 38.9 (previous all-time record 38.8) and Innisfail 41.0 (40.3), while South Johnstone Experimental Farm with 51 years of observations had the distinction of breaking its all-time record twice, finally arriving at 42.2 (40.4).
• Stations with at least a half-century of observations to set November high maximum records were Ingham 43.1 (42.0, broke record twice), Ayr DPI Research Station 41.9 (41.0), Lady Elliot Island 31.3 (31.0), Cardwell 40.0 (37.7, broke record twice), Townsville Airport 41.7 (41.0) and Collinsville Post Office 41.9 (41.6)
• As the heat built up, so the nights became warmer with many places recording their hottest November night on record at between 27 and 30°.
• The lengthy lists of high maximum and minimum temperatures are given in each day's Daily Weather Summary for Saturday 24, Sunday 25, Monday 26, Tuesday 27, Wednesday 28 and Thursday 29 November.
• Combinations of temperature, humidity and wind that lead to catastrophic fire danger have been observed only once before since the new Fire Danger Rating System (FDRS) was introduced in 2010. That was very briefly, only an hour or so, in the Birdsville area. On Wednesday 28 November, Rockhampton Airport recorded Catastrophic conditions for approximately three-and-a-half hours during the afternoon. It was the first time this area has recorded Catastrophic conditions and the most prolonged event in Queensland since the implementation of the current FDRS.

Bob Henson gives a detailed account of the QLD heat and bushfires in his Weather Underground blog. The Guardian expresses concern over the heatwave's impact on the Great Barrier Reef, Professor Terry Hughes tweeting "This is terrifying. An early summer heatwave breaks all records, lifting the chances of another episode of coral mortality on the #greatBarrierReef next Feb/March."

In the NT, heatwave conditions were reflected in all-time maximum temperature records of 38.7° at Gove Airport on 4 December (previous 38.0 in 40 years), Borroloola Airport 44.6 on 5 December (44.2, 25 years), and Groote Eylandt Airport 40.7 on 6 December (39.9, 20 years). A number of November and high minimum temperature records were also broken.

In WA, where high temperatures are a fact of life until The Wet arrives, only one high maximum temperature all-time record fell, but for emphasis it fell twice. Fitzroy Crossing's previous all-time record was 45.7° in 2009 in 23 years of observations. New maxima of 46.4 on the 7^th then 46.5 on the 8^th have reset it nearly a degree higher. Again, a number of November and high minimum temperature records were also broken.

In SE Australia, heat began streaming in from the NW on Friday 7 December, first reflected in some overnight November record high minima in SA, VIC and TAS. This continued on Saturday 8^th with November records for high minima broken in eastern VIC and TAS. The most noteworthy was at East Sale Airport where the minimum of 22.6° was a full 1.2° above the previous highest November minimum in 74 years of observations.

And an honourable mention goes to Macquarie Island, 1500km SE of Hobart, which had its hottest November day in 71 years when the mercury soared to 11.1° on 28 November. Two mornings later, the island had its warmest November night on record, 7.2°.

Wed 5 Dec 2018 NT: Yet another exceptionally high thunderstorm wind gust. Hard on the heels of three other remarkably high wind gusts with thunderstorms at Snowtown SA and Laverton and Wyndham WA comes the report of another, from the RAAF base at Tindal, 15km ESE of Katherine NT. At 19.10 CST the AWS anemometer recorded a gust of 131km/h along with a rapid 11.7° temperature drop and 19.2mm rain in 30 minutes. The all-time highest wind gust recorded in 16 years at the base had been 100km/h until this storm.

Sun 2 Dec 2018 BoM statement on the eastern Australian drought worth a read. The BoM has released Special Climate Statement 66 - an abnormally dry period in eastern Australia [pdf]. The Statement looks at rainfall deficiencies across NSW, VIC, inland QLD, Central Australia and eastern SA on a number of timescales, starting as far out as April 2012.

It says "The recent dry conditions in eastern Australia have few precedents for their combination of extent and duration. Whilst there have been individual years in the last century with rainfall similar to or less than that in 2018, only twice since 1900 have such dry conditions been sustained for a period of nearly two years across the Murray-Darling Basin. The intensity of the rainfall deficiencies in the Basin over the last two years is on a par with the worst seen in any individual two-year period during the Millennium Drought, although dry conditions have not yet been sustained for as long as they were during that event." It notes that the heaviest day's rain in the Murray-Darling Basin in 2018 up to the end of October was 17 October, with a Basin-wide average of 6.71 mm!

In addition to rainfall, the Statement examines temperature and humidity, soil moisture, evaporation and wind, and fire danger as well as the broadscale climatic drivers influencing the dry conditions. It finishes by placing this event in a longer-term context. This detailed report was released on 1 November before the rain in November. However, as the November Drought Statement points out, deficiencies on timescales over 11 months continue with little change in most areas.

Sat 1 Dec 2018 SA: Storm brings super-record wind in Snowtown. A supercell thunderstorm moving rapidly across Snowtown in Mid North SA produced a wind gust of 156km/h at 18.11 CDT. Snowtown, 125km NNW of Adelaide, lay under the strongest part of the supercell, seen in this BoM radar clip as the near-black core to the north of the head of Gulf St Vincent. The wind gust, which appears from video and the nature of damage to have been related to strong straight-line winds rather than a tornado, easily topped the Snowtown AWS's previous all-time record of 111km/h in 15 years of operation. The football club lost the roof of its just-completed pavilion and there was some structural and tree damage in the town of 650.

The supercell was part of a line of storms that crossed the state after a day of bushfires and strong winds. Media reports said over 8,500 properties lost power. [news.com.au, ABC]

Mon 3 Dec 2018 WA: Severe storms roll from Wheatbelt to Goldfields. Severe thunderstorms brought heavy rain and damaging winds in a strip from the Central Wheat Belt and Great Southern to the Goldfields during the afternoon. Bencubbin recorded 19mm between 14.00 and 14.30 WST while farther east Kalgoorlie-Boulder Airport reported a wind gust of 113km/h in the early evening. But the real humdinger of a storm was saved for Laverton, 250km NNE of Kalgoorlie. The AWS there recorded a wind gust of 137km/h at the same time as 16.0mm of rain was dumped in 5 minutes to 17.55 WST. It was the town's highest gust for any month in 15 years of observations, adding 19km/h to the previous record.

Tue 4 Dec 2018 WA: Severe wind in the Kimberley. Another day, another wind gust record shattered in a severe thunderstorm. While December is the month for strong thunderstorms across much of Australia, the winds accompanying some in the past few days have been extraordinary. Today 4^th the tropics turned it on with Wyndham receiving 31.8mm in 33 minutes to 14.30 WST accompanied by a wind gust of 128km/h. The previous December record wind gust was a mere 109km/h in a 15-year AWS history.

 NSW: A month's rain falls in two hours in Sydney
Wed 28 Nov 2018

Thunderstorms with torrential rain and gusty winds brought flash flooding to eastern Sydney on Wednesday 28^th right in the middle of the morning peak. The weather situation that produced the torrential rain, described as a one in a hundred year event in some locations, is described here.

Sydney's Observatory Hill recorded 73.4mm between 06.00 and 07.00 with a further 23.0mm to 09.00 for a storm total of 105.6mm, 22.0m above its November monthly average. All of that fell in the 3½ hours to 09.00 with the heaviest downpour 44.8mm in half an hour to 07.00. It was Sydney's wettest November day since the record 234.6mm fell in 1984.

The heaviest rain fell mostly around the city centre and on the lower North Shore. The Manly Hydraulics Laboratory's gauge at The Spit, near Mosman recorded 119mm in the storm to 09.00, the highest in the Sydney metropolitan area. A breakdown of that figure shows that 99mm fell in the hour to 07.44, but 66 of that fell in 30 minutes to 07.20 of which 31mm fell in 12 minutes and 19.5 in just 6 minutes. Those one hour and half hour figures have return periods for the site of one in a hundred years. Other heavy falls included 72.5mm in the hour to 06.30 at West Pennant Hills and 66mm in the hour to 06.55 at Chatswood Bowling Club.

Needless to say, conditions rapidly became chaotic through much of eastern Sydney. Road, rail and air services were disrupted, roads and railway stations flooded, and trees and powerlines were brought down. Three people lost their lives: a State Emergency Services volunteer on duty, and two people in the nearly fifty car crashes that occurred around the morning peak.

• Sydney Airport had to close two of its three runways, resulting in fifty flight cancellations and an even greater number of delays. Wind gusted to 87km/h at Port Botany in one of the take-off zones.
• Light rail services were cancelled, while some trains were cancelled or delayed.
• The storm made international news with Reuters, Al Jazeera and the BBC picking up the story.
• Over eight thousand properties in Sydney and on the Central Coast lost power.
• Emergency services made over 800 calls for assistance, including 15 flood rescues.
• A property in Chatswood suffered extensive damage when external windows were "sucked off" and internal ceilings and doors damaged.
• By around midday Thursday 29^th, the Insurance Council of Australia said over 1,600 damage claims had been lodged at an estimated value of $10 million. [SMH^‡]
• Storms, coupled with strong moist easterly onshore winds, brought heavy rain to the escarpment and hills behind the Illawarra and northern South Coasts. Porters Creek Dam, 15km NW of Ulladulla, recorded the state's highest total in the 24 hours to 09.00 with 152mm.

The SMH^‡ put together this photo record of a thoroughly miserable Sydney day, while the ABC compiled this from a frenetic social media.

[SMH, Floodlist, ABC]

 “Leaders of the world, you must lead”: COP24 begins
Mon 3 Dec 2018

Sir David Attenborough, broadcaster and natural historian, pulled no punches as he addressed representatives of nearly 200 of the world's governments at the opening of COP24 in Katowice, Poland, on Monday 3^rd.

Representing the world's people, he said "Right now, we're facing a man-made disaster of global scale, our greatest threat in thousands of years: climate change. If we don't take action, the collapse of our civilisations and the extinction of much of the natural world is on the horizon."

"Leaders of the world, you must lead. The continuation of our civilisations, and the natural world upon which we depend, is in your hands," he said.

An excerpt from his speech and report on the opening was carried by The Guardian, and video of the full ceremony is here*, with Sir David's contribution beginning at 1:44:30.

Described as the most important since the Paris Agreement of 12 December 2015, the Conference of the Parties (COP) is an annual meeting to track progress, ensure that climate action by governments is transparent and establish how climate finance is raised from rich nations to support climate action in developing ones. [UN, Reuters] COP24 has assumed greater importance because carbon dioxide emissions continue to increase and temperatures rise unabated, and it is becoming clear, as shown in the IPCC Special Report on Global Warming released in October, only extreme measures will now restrain warming below 2° by 2100.

These two images show the dramatic escalation in global temperature since 1980: a warming stripes bar graph, and the now familiar corkscrew brought up to date. World Bank CEO Kristalina Georgieva said before the meeting, “We are clearly the last generation that can change the course of climate change, but we are also the first generation [to bear] its consequences.”

More to keep you up to date

• 2018 is likely to be the fourth warmest on record globally. The 20 warmest years have been in the past 22 with the top four in the past four years, according to the World Meteorological Organization (WMO).
• Meanwhile, the latest WMO Greenhouse Gas Bulletin [pdf] showed that carbon dioxide reached a record 405.5ppm in 2017, the highest in at least the past 3 million years.  "The science is clear. Without rapid cuts in CO2 and other greenhouse gases, climate change will have increasingly destructive and irreversible impacts on life on Earth" said WMO Secretary-General Petteri Taalas. "The window of opportunity for action is almost closed"
• Mr Taalas also said that if the current carbon dioxide trend continues, temperature increases in the range of 3 to 5° would be likely by the end of the century, with the lower end of the range assuming countries acted on their Paris pledges. "If we exploit all known fossil fuel resources, the temperature rise will be considerably higher," he said. [Reuters]
• Australia is among the leaders in increasing its greenhouse gas output. The June 2018 Quarterly Update [pdf] shows a 1.3% rise over the previous quarter, the highest they have been since 2011 and the fastest rate of growth since 2004. At the same time, a UN annual emissions gap report says about half the G20 nations, including Australia, are falling short of their nationally determined contributions (NDCs) and Australian "emission levels for 2030 are projected to be well above the NDC target" although the government claims otherwise. [ABC, The Guardian]
• The Conversation published three detailed backgrounders to mark the beginning of COP24: What must be agreed to keep warming at 1.5°; COP24: What to expect; and Ten years on from Lehman Brothers, we can't trust finance with the planet.
• Some key backgrounders that set the scene for COP24: More you need to know, and what's at stake [UN]; the draft statement on the Global climate in 2018 and this more digestible quick and easy summary [WMO]; and the signals and impacts of climate change in extreme and altered weather in 2018 [WMO/Reliefweb].
• Finally, if you can keep up your practical optimism while those around you are losing theirs, The Guardian paints a grim Portrait of planet on the verge of climate catastrophe. It could be accused of needless scaremongering except that so much of what it says is borne out by the events of the past few decades and what is happening in the natural world. We must act and our leaders must lead with policies born of necessity.
  

 NSW, QLD: Queensland burns while Sydney floods
Wed 28 Nov 2018

Weather extremes covered the east coast from north of Cairns to south of Sydney today Wed 28^th, as out-of-control bushfires caused mass evacuations in QLD while one in a hundred year downpours brought flash flooding in and around Sydney. As opposed as these are, they are both products of the same weather system.

To understand how this could be so, take a look at this animation by Andrew Miskelly. In the hours before dawn this morning, a deep upper low with a surface companion moved east across NSW. This had already drawn tropical moisture down from northern Australia and now found an additional supply of moist Tasman Sea air as it approached the Hunter coast. What were moist easterly winds in Sydney swung around to be hot, dry offshore westerlies across coastal QLD where they fanned blazes that began days ago in heatwave conditions that have built up over more than a week of highly unusual westerly winds. In QLD, this is normally the build-up to the wet season, and the trade winds blow steadily from the southeast. A longer animation from Andrew is here. Sarah Fitton of the Bureau of Meteorology's extreme weather desk went into the situation in more detail with the ABC.

 QLD: Parched bush, extreme heat and wind bring first-ever Catastropic fire rating
Wed 28 Nov 2018

For the first time in QLD, the Catastropic fire danger rating, the most extreme level, was applied to the Capricornia and Central Highlands and Coalfields districts. Fears were held that strong dry winds accompanying 40° heat would create firestorm conditions. These were strong enough to whip up a dust storm in the Charleville area around dawn, which can be seen in Andrew Miskelly's animation, and this image from the BoM which also shows the widespread bushfire smoke in eastern QLD. Thunderstorms also produced high gusts, such as one of 124km/h at Lucinda Point mid-afternoon.

To give an idea of the extent of the fires, as of Wednesday evening 28^th:

• 138 fires were burning in the state
• Most of the eight thousand residents of Gracemere, just SW of Rockhampton, were evacuated
• People in nearby Stanwell were urged to leave immediately, as were those in Ambrose and Mount Larcom WNW of Gladstone, Deepwater, Baffle Creek, Rules Beach and Oyster Creek NW of Bundaberg, Carmila S of Mackay and Dalrymple Heights and Eungella W of Mackay
• People near the Carnarvon National Park on the Central Highlands, Waruman W of the Sunshine Coast and in Oxenford and Wongawallan inland from the Gold Coast were told to be prepared to leave. [ABC, QFES]

The largest blaze was the Deepwater fire which has burnt through 200sq km since Saturday and where some residents were still resisting requests to leave. The ABC and Brisbane Times ran live coverage through the day, while the ABC conveyed in pictures the drama and tragedy of an event most Queenslanders thought only happened in southern states.