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 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 28th, 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 28th:
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.
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 28th 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 29th, 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]
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