Sydney Extreme Fire Danger, SE Queensland | Australia weather Sat 7 Nov morning | Gus's Weather

Sydney Extreme Fire Danger, SE Queensland Storms - Sat 7 Nov Morning

[c06_radar_now]

GUS G'day, I'm Gus, and this is your Gus's Weather morning bulletin for Saturday the 7th of November.

GUS The big story for most of the country today is an extreme fire danger warning for Sydney and a wide stretch of New South Wales this afternoon, while south-east Queensland watches for severe storms tonight.

GUS It's about 5 am in Brisbane at the time this is uploaded.

GUS If something's happening in the sky where you are right now, drop it in the comments, I'll read a few through the day.

GUS Let's start with what's actually measured, not modelled, the Bureau of Meteorology's real radar for the whole country. The newest picture is about seven minutes old.

GUS The heaviest rain on the Bureau's scale is sitting right near Wollongong, New South Wales, just north west of the town, covering about 320 square kilometres of ground.

GUS There's heavy rain near Ballarat in Victoria, very heavy rain north west of Hughenden in Queensland, and very heavy rain east of Carnarvon in Western Australia.

GUS Of the capitals, Sydney has heavy rain right now, Melbourne has rain, Hobart and Canberra have light rain, and Perth, Adelaide, Brisbane and Darwin are clear on the radar.

GUS The model's simulated radar had these same areas in roughly the right spots overnight, so I'm comfortable the computer models have today's rain sorted.

GUS Everything in this bulletin is indexed in the video description, so if you're in a hurry, you can jump to the part you want from the chapters.

[c06_radar_now]

GUS Every day I check each of the 7 weather models I use against what actually happened, and I re-tune how much I trust each one.

GUS I review them over a day, a week and a month, three months and six months.

GUS Over the last week, GFS has had the smallest error on daytime highs, about 2.4 degrees.

GUS On rain it's the German model that has been closest.

[c04_satellite]

GUS One more measured picture before we move on, the satellite, because it shows how cold, and therefore how high, storm tops are, and it can see areas with no radar coverage.

GUS Over Canberra right now the cloud top is about minus 47 degrees Celsius, cold enough that there's genuine storm cloud sitting over the capital even though the radar only shows light rain there.

GUS Everywhere else the deep cold cloud is well out to sea, over the Coral and Solomon Seas more than 800 kilometres north east of Cairns, nowhere near people.

[c07_lightning_now]

GUS Lightning's worth a quick look too, it shows where storms are actually discharging energy right now, something radar alone can't always tell you.

GUS This comes from the Blitzortung lightning network, a volunteer network that picks up a sample of strikes, not every single one.

GUS The one cluster actually near people is close to Biloela in Queensland, where a few thousand people live nearby, ticking over quietly.

GUS The busiest patch by far is out north east of Mount Isa in Queensland, over a thousand strikes in the last six hours, but that's cattle country, not a town.

GUS Lightning's generally growing across the country this morning. No warnings come from this, for those it's always bom.gov.au.

[c05_obs_now]

GUS Before the forecasts, here's what's actually fallen, measured at Bureau of Meteorology weather stations, not modelled.

GUS A millimetre of rain is how deep the water would be if it collected in a flat gauge, a few millimetres of rain is a sprinkle, 25 millimetres of rain is a proper soak.

GUS The wettest spot in the country since nine o'clock yesterday morning is Mount Read in Tasmania, with 25 millimetres.

GUS Pound Creek in Victoria picked up 12 millimetres, with similar falls across the Victorian ranges at Mount Baw Baw and Ferny Creek, and it's actually raining there right now, just steady showers.

GUS The strongest gust anywhere overnight was 65 kilometres an hour at Wilsons Promontory in Victoria, enough to rattle outdoor furniture but nothing dangerous.

GUS Thanks to the Bureau of Meteorology for that network of stations.

[c16_index_map]

GUS The single biggest risk to the most people today is fire danger, so that's where I start.

GUS The Bureau of Meteorology has an extreme fire weather warning out for the Greater Hunter and Upper Central West Plains fire districts in New South Wales,

GUS both close to Sydney, as of 4 am Brisbane time this morning.

GUS Fire danger is measured with an index called the FFDI, think of it like a speedometer for how fast and fierce a fire could spread if one started.

GUS Across New South Wales today that index peaks at about 36 points, in the very high range,

GUS and in the districts under this morning's warning it's forecast to reach extreme, meaning a fire, once going, would be almost impossible to control.

GUS Part of that number comes from the drought factor,

GUS basically how dried out the grass and leaf litter already are from the last month or so of weather, and that's been high across inland New South Wales.

GUS There's a large high pressure system building over the Great Australian Bight, think of a high as a dome of heavier air sinking down, and it's dragging hot,

GUS dry north westerly wind down across inland New South Wales ahead of it, which, with the dryness, is exactly the recipe for extreme fire danger.

GUS If you're anywhere in the Hunter or on the Upper Central West Plains today, it's not a day for burning off,

GUS mowing on a tractor, or anything that throws a spark, and it's worth having your bushfire plan ready.

GUS For the official warning and any total fire bans in your area, check bom.gov.au.

[c17_temp]

GUS The next warnings are about heat, not thunderstorms, and heat matters because extreme heat is Australia's most dangerous weather, especially for the very young, the elderly and anyone working outside.

GUS The Bureau has an extreme heatwave warning for the Tiwi district near Darwin, and a severe heatwave warning for the Daly, Arnhem and Carpentaria districts, also near Darwin, both current as of early this morning.

GUS The Bureau also has a severe heatwave warning current for the Pilbara and North Interior districts in Western Australia,

GUS in place since early this morning, with daytime temperatures expected to sit around that same 34 degree mark for several days running,

GUS which is what turns ordinary heat into a heatwave, because the body and the land never get a proper break overnight,

GUS and that matters most for outdoor workers, the elderly and anyone without reliable air conditioning out that way.

GUS Darwin itself is forecast a top of 34 degrees today, overnight staying up near 26 degrees, that mix of heat and humidity not easing off is what makes a heatwave, not just the daytime number.

GUS That same severe heatwave warning for the Pilbara and North Interior districts was re-issued a little later this morning, still covering the same area,

GUS with overnight lows staying up around 26 degrees too, so there's no cool change to recover in, which is exactly what makes a heatwave dangerous over several days.

GUS And in Queensland there's a severe heatwave warning covering Cape York, the Gulf Country, the Northern Goldfields, Upper Flinders, and the tropical coast and tablelands around Cairns.

GUS Those are people working outdoors through genuinely dangerous heat, drink water, check on elderly neighbours, and the details of each warning are on bom.gov.au.

[c92_river_gauges]

GUS Now the flood side of things. The Bureau only flags the big, dangerous warnings, and right now there are two, both in inland Queensland.

GUS There's a moderate flood warning for the Balonne River, covering the stretch down to Surat, Warkon and St George, where the gauge at Warkon sits at 8.37 metres this morning and is holding steady.

GUS There's a moderate flood warning for the Barcoo River downstream of Isisford, through to Retreat, where the gauge at the Isisford Post Office was 4.54 metres this morning and actually falling.

GUS Elsewhere without a warning, Sydney's Port Jackson gauge is slowly rising to 1.22 metres and the Daly River near Katherine in the Northern Territory has come up to 3.15 metres, both just worth watching.

GUS For official warnings it's always bom.gov.au, and thanks to the Bureau for the gauge network.

[c01_verification]

GUS Quick check on how yesterday's forecast went, because that's how you know how much to trust today's numbers.

GUS Overnight lows across the capitals were mostly close, and every capital we called dry yesterday stayed dry, so the calls held up well.

[c02_mslp_fronts]

GUS Before the storm numbers, it helps to see the whole weather map, because that tells us what's pushing air where, and why.

GUS There's a strong high pressure system over the Great Australian Bight, 1030 hectopascals, the unit used for air pressure, sinking air pressing down and keeping things settled underneath it.

GUS That high is feeding the dry, gusty north westerly wind we just talked about into inland New South Wales, driving today's extreme fire danger.

GUS Out to the east there's a low pressure system over the Tasman Sea well south east of Sydney, with an upper level trough running from near Sydney itself out to that low.

GUS A trough is like a dent in the pressure pattern, a line where air gets squeezed and lifted, and lifting air is exactly what builds storms and rain,

GUS which is why we're watching storms build over coastal New South Wales and south-east Queensland today.

GUS Out over the tropical Pacific, well north east of Australia, there's a cluster of storms the European model's ensemble thinks has a reasonable chance of developing into a tropical system.

GUS It's thousands of kilometres from our coast, nothing to act on, but one to keep watching in bulletins to come.

[c07_cape]

GUS Now let's look at the fuel for tonight's storms, the stored energy in the air that a storm can feed on.

GUS Meteorologists call it CAPE, think of it like the petrol in a storm's tank, energy stored in warm, moist air.

GUS Offshore from Coffs Harbour it's about 2,645 joules per kilogram, and near Bundaberg about 1,634 joules per kilogram.

GUS Numbers like that, over about 1,000 joules per kilogram, mean the atmosphere has what it takes to build proper thunderstorms if something sets them off.

[c08_skewt]

GUS Energy alone doesn't make a storm, something has to break the lid off the pot.

GUS There's a layer of slightly warmer air above the surface called the cap,

GUS like a lid on a pot that stops warm bubbles of air rising freely, and today that lid is weak, so storms can get going without much trouble.

GUS The trigger is a southerly wind change.

GUS At Wollongong it's due through early afternoon, swinging from the north east around to the south,

GUS dropping the temperature and picking up to about 55 kilometres an hour, shoving under the warm moist air and forcing it up right where the atmosphere is primed.

GUS That storm fuel peaks late tonight, both near the coast and further inland.

[c12_index_map]

GUS The last ingredient is wind shear, how much the wind changes speed and direction with height, because that decides if storms stay messy or start rotating.

GUS Offshore from Coffs Harbour the rotating storm signal is modest, about 2 points, but near Bundaberg it's much higher, about 7 points.

GUS So tonight expect large hail and damaging wind off the coast, and heavy rain with some rotation inland.

[c10_sim_radar]

GUS Let's run through today in time order, because that's how it'll actually unfold.

GUS First up this afternoon, in the Gulf Country of Queensland near Normanton, thunderstorms are likely with a chance of hail, damaging wind and heavy rain, cattle station and coastal town country.

GUS This evening, severe category fire danger builds east of Mount Isa around Cloncurry, with very low humidity and gusty wind.

GUS Overnight, storms peak near Bundaberg with large hail.

GUS Further west, inland Western Australia, about 200 kilometres east of Newman, is forecast to reach catastrophic fire danger on Sunday,

GUS the worst category there is, remote cattle and mining country, and now is not the time to be near open country with anything that could spark.

[c19_model_compare]

GUS Before the capitals, here's how much I trust these numbers, because the models don't all agree.

GUS Near Bundaberg the models agree, between about 9 and 11 millimetres of rain.

GUS Off Coffs Harbour the models disagree more, so I lean toward the lighter, patchier outcome.

GUS The map also has the Canadian model and the American ensemble, they are in my blend too, and the last panel shows where all 5 models disagree.

[c90_events]

GUS A few big events on today with real crowds, so the weather actually matters for them.

GUS Tonight's Rugby League World Cup semi final at McDonald Jones Stadium in Newcastle, kicking off just before 6 pm, carries a real thunderstorm risk, with gusts up to 55 kilometres an hour.

GUS Over at Rosehill Racecourse in Sydney, the Everest Carnival's Ladies Day runs through the afternoon with a similar thunderstorm and rain chance, if you're headed there, pack a punt and a poncho.

GUS Down in Melbourne, Champions Stakes Day at Flemington and the Sandown 500 both carry a smaller chance of thunder and only light rain, nothing to change your plans.

GUS Sunday's second semi final at Allianz Stadium in Sydney looks more about wind than rain, gusts up to 70 kilometres an hour.

[c21_town_table]

GUS Right, the lap of the capitals, where someone's always having a better day than you, weather-wise.

GUS Today's high since this morning's low has already passed, so I'll give today's high, and tomorrow's low and high, plus the rain for each.

GUS Brisbane, a top of 29 degrees today with 0.1 millimetres of rain, tomorrow down to 19 degrees overnight then a top of 28 degrees with about 1 millimetre of rain, sunscreen weather.

GUS Sydney, a top of 28 degrees today with no rain, but tomorrow turns right around, down to 12 degrees overnight,

GUS only 18 degrees for the top, and about 9 millimetres of rain as a cooler change comes through.

GUS Canberra, a top of 21 degrees today, down to 1 degree overnight into tomorrow, a top of just 16 degrees, and about 2 millimetres of rain.

GUS Melbourne, only 14 degrees today with about 5 millimetres of rain, down to 6 degrees overnight, then 17 degrees tomorrow with another millimetre or two of rain.

GUS If you're doing the washing, hold off till Sunday afternoon.

GUS Hobart, 12 degrees today with a couple of millimetres of rain, down to 6 degrees overnight, a top of 14 degrees tomorrow, a proper jumper and a cuppa start.

GUS Adelaide, 18 degrees today and dry, down to 9 degrees overnight, a top of 24 degrees tomorrow, also dry. Good drying weather, the washing's laughing.

GUS Perth, 24 degrees today, dry, down to 15 degrees overnight, a top of 22 degrees tomorrow, also dry. Perth doing its usual thing, sunshine and not much else to report.

GUS Darwin, 34 degrees today with about a millimetre of rain, down to 26 degrees overnight, a top of 34 degrees again tomorrow with about 12 millimetres of rain.

GUS Darwin, you know the drill, hot, sticky, air conditioner earning its keep.

GUS Adelaide's forecast is bone dry again, the lawns are starting to take it personally. I'll see myself out.

[c21_town_table]

GUS Last piece, the week ahead, because we're not limited to just the next two days of data.

GUS This comes from a longer range European model's rain forecast, which tells us about rain but knows nothing about thunder or hail, and separately a set of storm ingredient flags from the American model.

GUS Day 2 and day 3 of this are fairly reliable, days 4 and 5 are a guide,

GUS and days 6 to 8 are only a signal that can shift completely, because tiny model errors grow bigger every day pushed forward.

GUS For the weekend storm verdict: south-east Queensland and Brisbane, storms likely again tonight, easing to just a shower chance by Sunday.

GUS Sydney, storms and showers likely tonight into Sunday as that change comes through, then it eases. Canberra, mostly dry with just a shower chance. Melbourne, showery today, drying out by Sunday afternoon.

GUS Looking further out to next Wednesday the 11th, a proper rain signal shows up along the south-east Queensland coast and across Victoria and Tasmania,

GUS with Brisbane and the Gold Coast around 25 millimetres of rain and similar falls further south.

GUS That's five days out, so take it as a guide, not a promise.

GUS Through the middle of next week the American model's ingredient flags also pick out central Queensland,

GUS the Top End and parts of Western Australia as holding plenty of that stored storm energy we looked at earlier, without an obvious trigger yet.

GUS Worth watching, not locking in a storm forecast, I'll have an update in this afternoon's bulletin as the picture firms up.

[c06_radar_now]

GUS Homework for today, if you're anywhere from Coffs Harbour to Bundaberg this evening, watch the sky after dark for a sudden gust of cooler wind, that's often the first sign a storm's about to arrive.

GUS A moment of wonder before we go, that high pressure system parked over the Bight is a dome of sinking air roughly the size of New South Wales and Victoria combined,

GUS quietly pressing down while everything else swirls around it.

GUS Why was the southerly change running late into Sydney today? It stopped to let the northerly finish its shift first. That one's for the dads.

GUS For all the official warnings, check bom.gov.au.

GUS I'll be back this afternoon with the next bulletin.

GUS If you'd like to keep up with these, hit subscribe, and if you've got a weather question, pop it in the comments, I'll get to as many as I can through the day.

GUS Look up now and then, the sky's the best show in town.

GUS Gus's Weather is a PandaVision production.