Extreme fire danger, heatwaves, and weekend | Australia weather Fri 6 Nov morning | Gus's Weather

Extreme fire danger, heatwaves, and weekend storms building

[c06_radar_now]

GUS G'day, I'm Gus, this is your morning bulletin for Friday the 6th of November.

GUS The big story over the next two days is extreme heat and fire danger out west, and storms building toward the weekend near Darwin, Gladstone and the New South Wales north coast.

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

GUS If you've got weather happening where you are, drop it in the comments, I'll get to as many as I can today.

GUS This is the Bureau's real radar for the whole country, not a model, and the newest picture is only 7 minutes old.

GUS The heaviest rain on the continent is well away from people, very heavy rain about 244 kilometres west of Kununurra in Western Australia.

GUS There's also very heavy rain right near Kununurra itself, and heavy rain up near Kowanyama in far north Queensland.

GUS Of the capitals, Canberra has rain on the radar this hour, with a touch of light rain over Sydney too; the rest are clear.

GUS The headline today is heat and fire risk out west, with storms building for the weekend.

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.

[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 2.3 degrees.

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

[c04_satellite]

GUS Radar only shows rain already falling. The satellite measures how cold, and so how high, storm tops are, which tells us how strong they are, and it sees where there's no radar at all.

GUS The coldest storm tops this morning sit over the Barkly Tableland and inland from Kununurra, down to minus 75 degrees Celsius, in cattle station country well away from towns.

GUS Of the capitals, only Darwin has real storm cloud nearby, patches down to minus 44 degrees just outside town.

GUS Worth flagging, the computer model's own simulated radar is running behind reality this morning, several of these real storm clusters have no matching storm on the model yet.

GUS So trust the satellite and the real radar over the model's detail today.

GUS That overnight build-up well inland tells us the atmosphere up there already has plenty of energy to work with, which matters for the weekend storms we'll get to.

[c07_lightning_now]

GUS Lightning trackers caught over 1,000 lightning strikes in the last six hours across the country, mostly up in the Top End and the Kimberley.

GUS The busiest cluster is about 311 kilometres north-west of Mount Isa, and it's easing off now.

GUS Another sits about 296 kilometres south-east of Katherine, also easing.

GUS There's a smaller cluster right near Mount Isa itself in Queensland, holding steady, with around 12,000 people within range of that one cluster.

GUS Further clusters sit east of Katherine and north-east of Halls Creek in Western Australia, all out over cattle station and highway country.

GUS That's the Blitzortung lightning network, a volunteer set of sensors, credit to them for this data.

GUS Nobody's in danger from any of this right now, but it shows the atmosphere up north already crackling before the bigger weekend storms.

[c05_obs_now]

GUS Before we forecast anything, let's look at what's actually fallen, measured by Bureau of Meteorology weather stations since 9 am this morning.

GUS Top of the list is Bradshaw in the Northern Territory, 24.6 millimetres of rain since 9 am. Daly Waters isn't far behind with 22.4 millimetres.

GUS Over in Tasmania, Mount Read picked up 11.8 millimetres, and Lord Howe Island off New South Wales had 11 millimetres.

GUS It's actually raining right now at several spots in the Tasmanian high country, and at Daly Waters in the Territory.

GUS The strongest gust measured was 96 kilometres an hour at Maatsuyker Island off Tasmania, with kunanyi, Mount Wellington above Hobart, gusting to 74.

GUS That's all measured, not forecast, it tells us what's already happened, not what's coming.

[c01_verification]

GUS Quick look in the rear view mirror before we go forward.

GUS Across 48 towns, our rain call was right 41 times and wrong 7 times,

GUS and our overnight lows were off by less than 2 degrees on average, with Moree the biggest miss, out by about 6 degrees.

GUS Melbourne was spot on for its overnight low, so the blend's doing alright.

[c02_mslp_fronts]

GUS Right, let's zoom out to the whole continent, this is the bit where I get to play weather detective.

GUS A strong high, 1029 hectopascals, is parked over the Southern Ocean well south-east of Albany, steering mostly dry air across the southern states.

GUS Up north, a scatter of weak lows sit over the Kimberley and western Queensland, nothing organised yet, each only around 1008 hectopascals, basically just low pressure where the heat and moisture are building.

GUS High above it all, there's a strong jet stream, winds over the Coral Sea topping 220 kilometres an hour, shifting south of Adelaide by tomorrow.

GUS Think of the jet stream as the fast lane up in the sky that steers the weather underneath it.

GUS Out over the Pacific, the computer models are also watching a couple of areas where a tropical low could try to develop over coming days,

GUS but there's no official system yet, no warning, and the models disagree hugely on whether anything comes together.

GUS Not a threat to the mainland right now, we'll keep watching.

[c07_cape]

GUS Next, the ingredient nobody sees but every storm needs, think of it as the humidity in your bathroom after a hot shower, but stretched across the sky.

GUS Near Darwin there's about 62 millimetres of moisture stacked up overhead, among the moistest air you'll see, typical of the build-up season.

GUS Storms also need fuel, warm moist air that wants to shoot upward like a cork released underwater.

GUS Meteorologists call that stored energy CAPE, in joules per kilogram, the more of it, the taller and stronger a storm can grow.

GUS Near Gladstone there's about 2,000 joules per kilogram of storm energy by Saturday night, a solid tank.

GUS Near Darwin it's about 3,300 joules per kilogram by Saturday afternoon, among the highest you'll see anywhere. Off Coffs Harbour it's about 2,600 joules per kilogram by Saturday evening.

GUS All three spots have the fuel. The question is whether something comes along to light it.

[c09_skewt]

GUS This is a model sounding, basically a core sample through the air above one spot.

GUS The line on the right is the air temperature going up, the line on the left is how moist the air is, close together means nearly saturated.

GUS Above Darwin there's only a weak lid today, about minus 6 joules per kilogram of inhibition, basically no cap holding the energy down.

GUS The air there only has to rise about 900 metres before cloud starts, and about 1,400 metres before storms can really take off,

GUS that's a low bar, so Saturday afternoon's heat on its own should be enough to set them going.

GUS Gladstone's lid is weak too, so expect storms to fire readily there as well once the afternoon heats up.

[c11_shear]

GUS Storms also need the wind to change with height, called shear, think of a spinning top getting tipped over so it rotates, that's what can turn an ordinary storm into one that rotates, a supercell.

GUS Near Gladstone and off Coffs Harbour, the wind through the lowest six kilometres changes by about 91 kilometres an hour, strong shear, enough to organise some supercells capable of large hail and damaging wind.

GUS Near Darwin the shear is a bit weaker, about 50 kilometres an hour, still enough for some rotating storms given how much fuel is there.

GUS Close to the ground the turning is weaker everywhere today, so look for powerful, well organised storms rather than a widespread outbreak of spinning storms.

[c12_index_map]

GUS Forecasters roll the fuel, the lid, and the spin into one number called the Supercell Composite.

GUS It's not a size guide, just how favourable the setup is, anything above about one is worth watching, several times that is a strong signal.

GUS Near Gladstone that supercell value is very high, and near Darwin it is too, both well above where storms can start to rotate, unusual for this time of year.

GUS The hail index tells a different story though, it's actually highest off Coffs Harbour, suggesting any storm there could carry larger hail, even with a lower supercell number.

GUS Remember, these are guidance about the environment, not a guarantee, they tell us the ingredients are there, not that a storm will definitely form exactly there.

[c18_model_compare]

GUS I check GFS, the European model, the European AI model, the Canadian model and the American ensemble against each other before committing to a number.

GUS Near Darwin the models spread a lot over the next two days, GFS wants about 27 millimetres of rain, the European model only about 7 millimetres, the European AI model around 13 millimetres.

GUS Confidence there is low, I'm leaning toward the lower end.

GUS Near Gladstone the three models agree much better, around 7 to 8 millimetres of rain over two days, moderate confidence.

GUS Off Coffs Harbour all three keep it light, under 5 millimetres, with strong agreement.

[c15_index_map]

GUS Fire danger is measured with an index that rolls together heat, dryness, wind and how dry the bush already is into one number.

GUS The higher it is, the faster and harder a fire would be to put out.

GUS By Saturday afternoon in central Western Australia, about 250 kilometres east of Newman,

GUS the fire danger index climbs deep into the extreme range, with the drought factor already at the maximum, meaning that bush is tinder dry.

GUS That's cattle station and highway country rather than towns, but any fire that starts there would be very hard to control.

GUS The Bureau has an Extreme Heatwave Warning out for the Kimberley district, its top category, meaning even well prepared people and stock there can be at risk,

GUS and a Severe Heatwave Warning for the Pilbara and North Interior districts of Western Australia, both current as of 4 am Brisbane time, full details at bom.gov.au.

GUS The Bureau also has a Moderate Flood Warning for the Balonne River between Surat and Warkon, with the Balonne River at Warkon gauge at 8.27 metres and rising.

[c16_temp]

GUS There's a further Severe Heatwave Warning covering the Peninsula, Gulf Country, Northern Goldfields and Upper Flinders districts of inland Queensland.

GUS That warning is current as of 4 am Brisbane time, and means the heat there is a real risk to health even for those taking precautions.

GUS The Bureau also has a Severe Heatwave Warning for the Daly, Arnhem and Carpentaria districts of the Northern Territory around Darwin,

GUS meaning a serious heat risk for people and stock through that region over coming days.

GUS A Severe Heatwave Warning also remains current for the Pilbara and North Interior districts of Western Australia, serious for people and livestock there even though it's one step below the extreme category.

GUS Through those inland warning districts the heat will feel brutal, even though the coast stays milder.

GUS Stay hydrated, check on anyone vulnerable, and the full warning areas are on bom.gov.au.

[c92_river_gauges]

GUS On the rivers, the Bureau has Moderate Flood Warnings out for the Balonne River around Surat and Warkon in southern Queensland, where the gauge at Warkon sits at 8.27 metres and is still rising,

GUS and for the Barcoo River around Isisford in western Queensland, where the gauge at Isisford Post Office is at 5.26 metres and is steady.

GUS Spreading out nationally, the Georges River gauge at Port Jackson in Sydney is at 1.34 metres and rising,

GUS the Bunyip River at Koo Wee Rup in Victoria is at 1.69 metres and rising, and the River Derwent at New Norfolk in Tasmania is at 0.6 of a metre and rising.

GUS None of those non-warning gauges are in flood, I'm just giving you the level on the gauge and the trend.

GUS Official flood warnings and what they mean for your area are on bom.gov.au, credit to the Bureau for all these readings.

GUS There's also a Moderate Flood Warning for the Balonne River between Surat and Warkon.

GUS One more thing before any of this rain falls, how wet the ground already is. Around Rockhampton it's drying out, around Darwin it's still dry, and around Coffs Harbour it's wet too.

GUS That's an estimate from one town per region using observed rain from SILO, a Queensland Government data service, not every paddock, but it gives a sense of how the next rain will behave.

[c10_sim_radar]

GUS Let's walk through how today unfolds.

GUS This afternoon, storms are likely over the Gulf Country of Queensland, out near Normanton and Doomadgee, capable of hail, damaging wind and heavy rain, in country with stations, a highway and a handful of towns.

GUS Also this afternoon, similar storms are likely near Port Hedland in Western Australia's Pilbara, home to about 15,000 people, worth watching if you're there.

GUS Storms are also possible in north-east Western Australia, about 180 kilometres north-east of Broome, in cattle station and highway country with few people about.

GUS Both are inland storms where the air mass is most unstable, so expect stronger, more organised cells rather than a widespread soaking.

[c10_sim_radar]

GUS Tomorrow, Saturday afternoon, the focus shifts to the north-west Northern Territory, about 30 kilometres south of Darwin, where we're tracking the highest supercell number in the country.

GUS Storms there could bring large hail, damaging wind gusts and heavy rain into the city itself.

GUS This is also classic build-up season for the Top End, the south-east trade winds that carried the dry season's weather have swung around and the old pattern has cut off,

GUS so the heat and humidity keep climbing and afternoon storms become the main event until the monsoon rain arrives in December.

GUS Build-up storms are hit and miss by nature, so if you're in Darwin, watch the sky this afternoon rather than banking on a specific time.

[c14_rain_wind]

GUS Saturday evening, storms are also likely near Derby in the Kimberley.

GUS By Saturday evening, two coastal spots light up too, off Coffs Harbour with the highest hail risk we're tracking,

GUS and over the Coral Sea about 30 kilometres south-east of Gladstone, with the highest supercell number in the country.

GUS Storms like this can join up overnight into one bigger cluster, meteorologists call it a mesoscale convective system,

GUS which is why one town gets smashed with rain and the next gets nothing, so don't be surprised if it's patchy.

GUS Near Gladstone, Rockhampton and Bundaberg should only see light rain through Saturday, under 10 millimetres, with a better soaking chance arriving early next week, so don't lock that in yet.

GUS Near coastal areas it really is luck of the draw who gets hit and who misses out entirely, while inland the storms are stronger and more organised.

[c90_events]

GUS A few big events this weekend worth a weather note.

GUS At Newcastle on Saturday evening, the Rugby League World Cup semi-final has a real thunderstorm risk, gusts up to about 55 kilometres an hour and around 3 millimetres of rain, lightning means a stoppage.

GUS At Rosehill, Ladies Day at the Everest Carnival also carries a thunderstorm risk Saturday, with some rain likely later in the day.

GUS At Flemington in Melbourne, Champions Stakes Day should see occasional rain and a chance of a storm, gusts to about 56 kilometres an hour, bring a coat more than an umbrella.

GUS And at Sandown, the Supercars crowd should just plan on a wet weekend, though not much thunder, the rain chance there is very high.

[c20_town_table]

GUS Let's do the lap of the capitals, today and tomorrow, low and high both, plus the rain.

GUS Brisbane reaches 26 today, no rain, and tomorrow's low 17, top 29, still dry, nothing to worry about.

GUS Sydney tops out near 23 degrees today with under a millimetre of rain, basically dry. Tomorrow's low is 15 degrees, the top near 29 degrees, and dry again, good washing weather.

GUS Melbourne sits around 22 degrees today, dry, but tomorrow turns cooler, low 7 degrees, top only 14 degrees, with about 5 millimetres of rain, keep a coat handy, Melbourne being Melbourne.

GUS Perth is a sunny 29 degrees today, no rain, barely changes tomorrow, low 15 degrees, top 24 degrees, just a touch of rain. Perth doing its usual thing, sunshine and a bit of smugness.

GUS Adelaide reaches 20 degrees today, dry, and about the same tomorrow, low 10 degrees, top 18 degrees, next to no rain. Good drying weather, the washing's laughing.

GUS Darwin is the hot one, a top of 35 degrees today with a little rain about,

GUS and tomorrow a top of 34 degrees with a better chance of a shower or storm, about 3 millimetres of rain, that's the build-up for you.

GUS Canberra reaches 23 degrees today, next to no rain, and tomorrow's low is 6 degrees, the top 20 degrees, still dry.

GUS And Hobart tops out at 16 degrees today, dry, but tomorrow turns showery, low 6 degrees, top 12 degrees, about 4 millimetres of rain, a proper jumper and a cuppa sort of day down there.

[c20_town_table]

GUS Let's look further ahead, days two through eight, using a European model's nine-day rain signal. This only tells us about rain, nothing about thunderstorms or hail, so it can say wet, never stormy.

GUS For south-east Queensland, the next four days stay mostly dry, but by next Wednesday the signal turns wet, the Gold Coast could see over 20 millimetres of rain.

GUS Central Queensland sees light showers building through the weekend, then a heavier signal by next Thursday, Rockhampton up near 36 millimetres of rain.

GUS Northern New South Wales turns wet midweek too, Coffs Harbour up near 20 millimetres of rain next Wednesday, Newcastle even wetter, about 24 millimetres, the Thursday after.

GUS The Top End stays showery on and off right through, with tomorrow the wettest day in this run.

GUS Victoria and Tasmania pick up showers this weekend, Melbourne around 7 millimetres of rain both Saturday and again next Wednesday.

GUS Looking just at the ingredients, next Tuesday has plenty of stored storm energy over inland Queensland and the Top End but nothing obvious yet to trigger it, so storms there could easily fizzle.

GUS Next Wednesday central Queensland has both the energy and something to set it off, worth watching for a decent inland soaking.

GUS Days two and three in this outlook are fairly reliable, days four and five a guide,

GUS beyond that it's only a signal that can change completely from one run to the next, small errors in the model grow every day.

GUS We'll update it again this afternoon.

[c17_ens_prob]

GUS Now the weekend verdict for the big population centres, since a lot of you are planning around it.

GUS South-east Queensland: storms stay well north near Gladstone, Brisbane itself dry Saturday, a shower possible Sunday.

GUS Sydney should stay mostly dry Saturday, with just a slight chance of an afternoon storm.

GUS Canberra stays dry and cool both days.

GUS Melbourne is the wet one of the big cities this weekend, showers Saturday continuing into Sunday, pack the brolly if you're at Flemington or Sandown.

GUS Overall my confidence in today's numbers is high. The rain near Gladstone and Coffs Harbour is fairly solid, it's the exact totals right over Darwin, where the models spread most, that I'd watch most closely.

GUS Check back this afternoon, a weekend forecast changes as it gets closer.

[c06_radar_now]

GUS Why did the high pressure system over the Southern Ocean refuse to budge? It had already found its happy isobar. I'll see myself out.

GUS Here's your homework for today, if you're anywhere near Darwin or Gladstone this afternoon, watch for tall, anvil shaped clouds building early, that's the first sign these storms are getting going.

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

GUS My next bulletin is this afternoon.

GUS If you've got a weather question, pop it in the comments and I'll work through them during the day.

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

GUS Gus's Weather is a PandaVision production.