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Curious Brisbane: For city starved of summer storms, their arrival is better late than never

Jessica Hinchliffe, Monday March 18, 2019 - 16:50 EDT
ABC image
Summer was gone before the storms reappeared over south-east Queensland. - ABC

Brisbane is known for its annual thunder and lightning shows during the warmer months, so where were the storms hiding last summer?

The irony is not lost on this writer, who when preparing this story sheltered from yet another of the severe storms to affect south-east Queensland in recent days.

So despite these autumnal downpours bringing upwards of 100mm across the region — exceeding the average March rainfall total in some places — the usually active storm period from towards the end of 2018 was missing in action.

Lightning struck the West End home of Ian Lowndes in 2014, burning the roof and top floor, but that didn't dampen his enthusiasm for a great storm.

"It's our reward here in Brisbane at the end of a hot and muggy day, and this year's storm season really has been disappointing," he said.

It's been a question posed to many times over the past few months.



Early start and early end to season

Bureau of Meteorology senior forecaster Jonty Hall said many factors played into the uneventful summer storm season.

"In October last year we had a short storm period and then things switched off once November started and didn't come back in the summer," he said.

"We haven't had the right atmospheric conditions to support thunderstorms."



He said the ingredients for storms had to align for the magic to happen — which has been seen over the past five days in Queensland.

"Typically, you need colder air in the mid-levels of the atmosphere as that provides instability, and then you need warm and moist air near the surface," Mr Hall said.

"Warm and humid conditions are the fuel for the thunderstorms, and you need a feature to lift the air and get the storm going to develop thunderstorm activity.

"If you're missing one of those ingredients, then you don't get thunderstorms."



Hot weather not always enough

Although warm temperatures prevailed through the summer, Mr Hall said the other necessary ingredients were not strong enough to support storm formation.

Upper-level troughs that usually provide instability for storms to lift had been blocked due to the large upper-level high pressure systems that had been sitting in place over much of southern Queensland.

"Primarily it's been because of blocking patterns persistent through the summer period, which is why we didn't get the usual progression from west to east of weather systems," Mr Hall said.

"The upper-level troughs have been shunted towards southern Australia and down around Sydney and further south in NSW where they have had a bumper storm system.

"Hence, we've been starved of thunderstorms through summer."



Is Brisbane's geography to blame?

Local rumours and theories often suggested that Brisbane's location was the reason storms could be hit and miss — some of which were true, Mr Hall said.

"Geography can affect the movement of storms and there's always a local theory about the terrain and preventing storms getting here, and some have a grain of truth to them.

"In the Brisbane area, we're down on the coastal plain and we have the more elevated terrain to the west.

"If you get storms developing on those elevated areas to the west, and you have strong winds in the higher atmosphere pushing towards the coast, then Brisbane receives storms."



Mr Hall, who also travels across the world documenting storms, believes Brisbane storms stand up on the world stage.

"We're not in the same playing field of the central plains of the United States, which is the storm capital of the world, but we can claim super-cell thunderstorms and we see severe storm activity," he said.

"Super cells are rotating storms and are associated with hailstones that are larger than five centimetres in size and we can get tornadoes in the south-east of Queensland too.

"By world standards Brisbane doesn't do too badly when it comes to storms, and we do better than many parts of Australia."



What about the lack of rainfall?

Many places in Australia rely on a wet season over summer for their annual rainfall — for Queensland, storms usually provide a majority of the rain.

SEQ Water's Mike Foster said dam levels were lower than normal for this time of year due to the lack of storms.

"Dam levels across south-east Queensland are sitting just above 70 per cent capacity as we've had a hot and dry summer," he said.

"When our levels hit 70 per cent, we will start a conversation with the community asking them how they're using water and, most importantly, that they're not wasting water as dam levels go down."



The summer heat had led to soaring water consumption rates across south-east Queensland, Mr Foster said.

"In particular this summer in January and February, our consumption rate was 25 litres per person per day more than we were this time last year.

"In January itself we saw the highest water use since before the Millennium drought and that was 240 litres per person per day."



He added that if no significant rain fell over the next 12 months, dam levels would drop to restriction levels.

"By the end of the year it could be 60 per cent capacity if we get no further rain.

"At this stage, though, we are 12 months away from formal restrictions and we would be looking at March or April next year if we don't get decent rainfall."

Who asked the question?



Brisbane resident Ian Lowndes missed the summer storms and said they were the reward at the end of a hot and muggy day in the city.

The landscape architect, who has a true passion in bush restoration, has a vested interest in good rainfall.

Originally from the Gold Coast, Mr Lowndes has lived in Brisbane for 30 years and loves that you can buy a house with a backyard lawn while still living close to the city.

While you're here… are you feeling curious?


- ABC

© ABC 2019

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