Gulf Country Storms, Northern Heatwave | Australia weather Thu 5 Nov morning | Gus's Weather

Gulf Country Storms, Northern Heatwave and Fire Risk Thu 5 Nov

[c06_radar_now]

GUS G'day, I'm Gus, and this is your Thursday the 5th of November morning bulletin.

GUS The big story today is storms building over northern Australia this afternoon and evening, while a wet, showery pattern sits over the south-east capitals right now.

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

GUS This is the Bureau of Meteorology's own radar, the real measurement for the whole country, and the newest picture is only about 8 minutes old.

GUS The heaviest rain is out east of Fitzroy Crossing in Western Australia, very heavy over about 4,000 square kilometres, with very heavy rain also near Sydney.

GUS There's a band of rain sitting offshore south-east of Hobart, and up in Queensland very heavy rain just south of Mackay, with the top of the Bureau's scale right near Airlie Beach.

GUS This morning the capitals with rain are Perth, Melbourne, Canberra, Sydney and Brisbane with heavy falls, Hobart with light rain,

GUS Adelaide and Darwin both clear, and the model's simulated radar broadly agrees with what's actually falling.

GUS Tell me in the comments what the sky's doing where you are right now, I'll read as many as I can today.

[c06_radar_now]

GUS Every day I check each of the 6 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, then three months and six months as the record grows.

GUS Over the last week, GFS has had the smallest error on daytime highs, about 2.3 degrees.

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

[c04_satellite]

GUS Satellites measure how cold, and therefore how high, the top of a storm cloud is, and that tells us how strong it probably is, even where there's no radar to see it.

GUS The satellite also shows a very strong storm out near Halls Creek in Western Australia,

GUS its cloud top down near minus 84 degrees Celsius, about as cold and tall as storms get, over more than 13,000 square kilometres.

GUS That storm isn't showing up properly on the model's own forecast radar yet, so out that way the model is running a little behind, and the satellite is the real measurement to trust.

GUS So the headline for today: storms firing up over northern Australia through this afternoon and evening, heat warnings in the tropics, and a wet pattern in the south-east.

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

[c05_obs_now]

GUS Before we get to the forecast, here's what's actually fallen, measured by Bureau of Meteorology weather stations.

GUS The wettest spot in the country since 9 am this morning is Mount Baw Baw in Victoria's high country,

GUS 31 millimetres of rain, a millimetre being roughly what collects in a gauge if you held one out in it.

GUS Ferny Creek near Melbourne has had 25 millimetres and it's a chilly 8 degrees there right now, and Mount Buller's had 21 millimetres with snow-season temperatures below zero.

GUS Down on the coast, Newcastle has picked up 24.6 millimetres of rain in the last 24 hours, and it's still raining there this morning.

GUS The strongest gust in the country overnight was 100 kilometres an hour at Wilsons Promontory in Victoria, with Cape Grim in Tasmania close behind at 63.

GUS Spare a thought for anyone camping up at Mount Baw Baw this morning, that's a proper rug-up, zip-the-tent-flap kind of start to the day.

[c07_lightning_now]

GUS Lightning's tracked across the whole country by a volunteer network called Blitzortung, and I'll credit them once, this is their data.

GUS The busiest patch right now is out at sea about 200 kilometres east of Sydney, with over 4,600 lightning strikes picked up in the last six hours, though that's offshore and steady, not growing.

GUS Inland, there's lightning north-west of Alice Springs and north-west of Mount Isa, both easing off now, and a patch south-west of Cairns ticking along steadily.

GUS The one worth watching is out that same way in the Kimberley, only a couple of hundred strikes so far but it's growing, and that's a populated area.

GUS Overall, lightning across the country has been fairly steady in the last hour but building over the last six, so there's more where that came from today.

[c01_verification]

GUS Quick look back, because that tells you how far to trust today's numbers.

GUS Yesterday's overnight lows for every capital I checked, Adelaide, Brisbane, Darwin, Hobart, Melbourne, Perth and Sydney, all came in spot on, within a degree.

GUS On rain, across the country yesterday I got twelve calls right, missed four showers that fell anyway, and called six false alarms that stayed dry, a solid but not perfect strike rate.

GUS So, high confidence on temperatures today, and reasonable but not perfect confidence on exactly where the rain falls.

[c02_mslp_fronts]

GUS Before the detail, the Bureau's own safety warnings, because those come from them, not from my analysis.

GUS The Bureau has extreme heatwave warnings out for the Tiwi District near Darwin and for the Kimberley in Western Australia, their most serious heat category.

GUS There's also a Severe Heatwave Warning for the Daly, Arnhem and Carpentaria Districts near Darwin.

GUS There's also a Severe Heatwave Warning for the Pilbara and North Interior Districts, their second-most serious heat category.

GUS And a moderate flood warning for the Barcoo River, covering it down to Blackall, still rising.

GUS There's also a Moderate Flood Warning for the Balonne River to Surat, the Balonne River at Warkon near 7.52 metres and further downstream, all still in moderate flood.

GUS You can see the full detail of any of these on the Bureau's own website.

GUS On the bigger picture, there's no actual tropical cyclone anywhere near Australia right now, just a couple of disturbances far out in the Pacific the models don't expect to come near us.

GUS What's driving today's weather is a low pressure area over the north-west, high pressure over southern Queensland, and an upper-level dip in the atmosphere trailing from western New South Wales down past Tasmania.

GUS That upper dip is why the south-east capitals all have rain on the radar this morning, it's lifting air right across that corner of the country.

[c03_upper_500]

GUS One more layer before the storms: what's moving high above the ground, and how much moisture is actually in the air to work with.

GUS High above us there's a pocket of spinning cold air, a cutoff low, sitting out in the Tasman Sea,

GUS and a fast river of wind, the jet stream, howling past Tasmania at up to 240 kilometres an hour.

GUS Lower down, think of moisture like a sponge: the air up north is thoroughly soaked,

GUS holding more than 50 millimetres of what's called precipitable water, a measure of how much rain the whole column of air could wring out.

GUS Down over Hervey Bay and Bundaberg in Queensland the air's far drier, only around 19 millimetres, so any storms there will be more ordinary, less likely to produce a real soaking.

[c07_cape]

GUS Now the ingredients for today's storms, starting with the fuel in the air.

GUS Meteorologists measure the energy a storm can feed on and call it CAPE, think of it like the petrol in a storm's tank, measured in joules per kilogram.

GUS Near Normanton there's about 3,100 joules per kilogram of that stored storm energy this afternoon, a serious tank for building tall storms.

GUS Up near Darwin, over the Arafura Sea just north-west of the city, there's about 2,500 joules per kilogram of that stored storm energy, nearly as much.

GUS Oh, I love this one: three thousand joules in every single kilogram of that tropical air is roughly the energy in a few sticks of dynamite, just waiting for something to light the fuse.

GUS So, plenty of fuel in both places. The question now is whether anything sets it off.

[c10_sim_radar]

GUS Having that storm energy isn't enough on its own, a storm also needs a lid to build under and then something to break that lid.

GUS The lid, what forecasters call the cap, is a layer of warmer air above the surface that stops bubbles of warm air rising, like a lid on a pot.

GUS Today it's almost nothing in both places, basically no lid holding things down.

GUS With barely a lid, the trigger is a wind change swinging through late Thursday, expected around 7 pm local time, that's the spark that should get storms firing properly.

GUS By about 4 pm storms fire up near Normanton with hail, damaging wind and heavy rain possible.

GUS And up near Darwin, a separate batch of storms is likely through the morning, closer to about 6:30 am local time, with the heaviest rain rates expected to the city's south by this evening.

[c11_shear]

GUS One more ingredient decides what shape these storms take: how much the wind changes with height, what forecasters call shear.

GUS Think of it like traffic on a multi-lane road, all moving the same speed and direction, cars just bump along. Change the speed or direction at different levels and things start to organise and rotate.

GUS Over the Gulf Country there's about 71 kilometres an hour of that wind shear through the lowest six kilometres of the atmosphere, and about 60 kilometres an hour near Darwin, both decent for organising storms.

GUS With that much shear on top of all that fuel, expect some storms today to become organised multicell clusters, and a few could even start to spin, what's called a supercell.

GUS So, several of today's hazards are on the table, and I wouldn't rule out a rotating storm or two, though the numbers don't point to anything extreme.

[c12_index_map]

GUS There's a supercell value, how well the atmosphere supports a rotating storm, out in western Queensland this evening, and it's genuinely high.

GUS What stands out more is the downdraft energy, how hard a collapsing storm can slam wind into the ground.

GUS That's elevated up north, so damaging wind gusts are the hazard I'd watch hardest today.

GUS Loose trampolines, outdoor furniture and anyone camping under trees up that way should be tied down or avoided tonight.

[c18_model_compare]

GUS Before I commit to a rain total, I check the American GFS, the European model and the European AI model against each other.

GUS Up north the three only loosely agree, with totals in the next 24 hours ranging from about 1 to 6 millimetres,

GUS call it 3 to 10 millimetres overall, modest for how much storm energy is around.

GUS Near Darwin they're a bit further apart, the European AI model much lighter than the other two, so I'm leaning toward something in the middle, a decent shower with isolated heavier falls.

GUS That's the honesty bit: how much rain falls where these storms actually track is still genuinely uncertain, don't lock in an exact number.

[c15_index_map]

GUS Near Port Hedland this morning the fire danger reaches severe, well up in the severe range on the fire danger index, with temperatures near 41 degrees,

GUS humidity down near 11 per cent and gusts near 60 kilometres an hour, hot dry country with the towns and the port itself nearby.

GUS Out in the Gibson Desert further south, fire danger is forecast to reach catastrophic, the Bureau's top category, by Friday afternoon, the country's most severe rating.

GUS That desert country matters for the stations, the tracks and the highway out that way.

GUS There's also a Severe Heatwave Warning for the Peninsula, Gulf Country, Northern Goldfields and Upper Flinders districts, with temperatures forecast into the low 40s this week.

GUS There's also a second Severe Heatwave Warning for the Pilbara and North Interior Districts, with overnight temperatures staying above 30 degrees.

[c90_events]

GUS Quickly, a few of the week's bigger events and what the sky's doing for them.

GUS Oaks Day at Flemington in Melbourne is on today, a top of 16 degrees and barely any rain forecast, good news for the frocks and the fascinators.

GUS The Foo Fighters play Suncorp Stadium in Brisbane tonight, and the forecast there is dry with no rain expected, a good night to be outdoors.

GUS Melbourne's got a busier weekend though: the Supercars at Sandown and Champions Stakes Day at Flemington on Saturday both carry a good chance of some rain and gusty wind, so pack a jacket.

GUS Sydney's Everest Carnival and the Rugby League World Cup semi-finals look mostly fine, just breezy around 33 to 34 kilometres an hour.

GUS Why did the rain skip Flemington for Oaks Day? It already had a full card. I'll see myself out.

[c92_river_gauges]

GUS When rain falls, I also check river levels nationwide, because that's often where the real impact shows up, from gauges right across the country.

GUS The Barcoo River at Isisford is rising, now at 5.31 metres on the gauge, and the Balonne River at Warkon has climbed to 7.52 metres, both under the moderate flood warnings I mentioned earlier.

GUS Dandenong Creek is rising with all that rain falling in Victoria's ranges, and the Adelaide River has jumped more than a metre since our last bulletin.

GUS Elsewhere it's quieter: the Murray at Swan Reach in South Australia and the Warrego in New South Wales are both steady, and gauges further south are barely moving.

GUS Those river heights come from the Bureau of Meteorology's own gauge network, and for any official flood warnings, the place to check is always bom.gov.au.

[c20_town_table]

GUS Now the full lap of the capitals, their actual numbers: today's high, since most of you have already had your overnight low, plus tomorrow's low and high, and the rain for each day.

GUS Brisbane's had a muggy start with that morning rain easing, a top of 34 degrees today,

GUS and tomorrow a low of 18 degrees and a high of just 26 degrees as cooler air moves in, nothing to worry about rain either day.

GUS Sydney gets about a millimetre of rain today, a top of 22, tomorrow 15 to 23, an umbrella in the bag is plenty.

GUS Melbourne's the wet one today, nearly 14 millimetres of rain with a top of just 18 degrees, so grab the umbrella, tomorrow drier, a low of 7 degrees and high of 22 degrees.

GUS Canberra gets about 2 millimetres of rain today, a high of 21 degrees, drying out as it cools toward tomorrow's low of 4 degrees and a high of 23 degrees.

[c20_town_table]

GUS Four more capitals, and these ones tell a very different story from the wet south-east I just went through.

GUS Hobart's had almost 9 millimetres of rain overnight with a top of 18 degrees today, easing to a top of 16 degrees tomorrow, still a bit damp down there.

GUS Adelaide's basically dry, a top of 19 degrees today and 21 degrees tomorrow, good drying weather if you've got washing on the line.

GUS Perth's had a brief wet start that's clearing, a top of 27 degrees both today and tomorrow, sunnies rather than the umbrella.

GUS Darwin's under that severe heatwave warning, a top of 34 today and 2 millimetres of rain, tomorrow 35 and nearly 11 millimetres.

GUS Why did the high pressure system over Adelaide get such an easy week? It's got nothing but a sunny disposition and no front to deal with. That one's for the dads.

[c18_model_compare]

GUS Now the week ahead, a rain signal from a European model's nine-day forecast, it shows how much rain but nothing about thunder or hail, so I can say wet, not stormy.

GUS Friday looks mostly dry for the south-east capitals. Saturday's the day to watch: showers for Victoria's ranges, showers near Newcastle in northern New South Wales, and showers developing in south-east Queensland too, easing by Sunday.

GUS Canberra stays mostly dry and cools off through the weekend.

GUS Looking further out, Sunday and into Wednesday there's plenty of stored storm energy forecast again over south-east Queensland,

GUS central and north Queensland and the Top End, but the models aren't confident anything will set it off, so it could easily fizzle rather than fire.

GUS Northern New South Wales looks mostly quiet until Wednesday, when both models agree on a soaking, heavy rain, especially around Moree.

GUS Ground-wise, south-east Queensland and Victoria are already sitting very wet from recent rain,

GUS so any new falls run off faster and rivers rise quicker than usual, while the Top End is actually still quite dry despite the heat.

GUS Days two and three I'd trust, four and five are a guide, and anything from day six on is only a rough signal that can flip completely by the next bulletin, so check back.

GUS This is all about the ingredients, not a promise, worth watching rather than locking in.

[c20_town_table]

GUS Overall my confidence today is high, a plain-words way of saying the bigger weather systems are well agreed on, it's the exact placement of these northern storms that's the harder call.

GUS Your homework for today: watch for a sudden darkening sky to the west before you hear any thunder, that's usually your first real warning.

GUS I'm a robot, so I don't feel the humidity in Darwin today, but I do feel for anyone out there in it.

GUS The next bulletin is this afternoon, and for all the official warnings, check bom.gov.au.

GUS If you've got a weather question, pop it in the comments and I'll get to as many as I can during the day,

GUS and thanks for watching, let me know what's happening overhead where you live too.

GUS Subscribe if you want this every morning and afternoon.

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

GUS Gus's Weather is a PandaVision production.