Extreme Heat, Fire Danger and a Weekend | Australia weather Fri 6 Nov afternoon | Gus's Weather

Extreme Heat, Fire Danger and a Weekend Storm Threat for Queensland

[c06_radar_now]

GUS G'day, I'm Gus, and this is the afternoon bulletin for Friday the sixth of November.

GUS The big stories today are extreme heat and extreme fire danger building across the north and west, and a severe storm signal taking shape for the weekend near Rockhampton and Gladstone in Queensland.

GUS It's about 3 pm in Brisbane at the time this is uploaded.

GUS This is the Bureau of Meteorology's real national rain radar, not a model, and the newest picture is only a few minutes old.

GUS The heaviest rain it can see is very heavy, remote country north-west of Longreach, with another very heavy patch south-east of Mount Isa.

GUS Out to sea well south of Hobart there are big but only moderate patches of rain, and among the capitals Sydney,

GUS Canberra and Hobart have rain right now, Brisbane a light patch, Perth, Adelaide, Melbourne and Darwin clear.

GUS The model's simulated radar only found two of those patches this hour, we'll check that against the satellite next.

GUS If you're in a hurry, jump to the part you want from the chapters in the description.

[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 Next, the satellite, because it measures something radar can't, how cold and so how high storm cloud tops are,

GUS which tells us how strong a storm is, and it can see where there's no radar at all.

GUS The biggest, coldest storm cloud right now is over the Gulf of Carpentaria, remote water north of Gununa, a top of minus 76 degrees Celsius, genuinely powerful even over open water.

GUS The Bureau also has a severe heatwave warning out for the Peninsula, Gulf Country, Northern Goldfields and Upper Flinders districts.

GUS Darwin has some storm cloud sitting overhead this afternoon, cold enough to count as a real thunderstorm.

[c07_lightning_now]

GUS Here's where lightning has struck over the last six hours, tracked by the Blitzortung lightning network, a volunteer network of ground sensors.

GUS The busiest cluster is out at sea north of Gununa, over 1,000 lightning strikes in the past six hours and easing now.

GUS There's a growing cluster south of Newman in Western Australia.

GUS Overall, lightning has picked up a little in the last hour, dozens of strikes, after easing through the afternoon.

[c05_obs_now]

GUS Before forecasts, here's what's actually fallen, measured by Bureau of Meteorology weather stations since 9 am this morning.

GUS The wettest spot in the country is Mount Read in western Tasmania, 16.4 millimetres since 9 am, a millimetre being roughly what collects in a rain gauge, so that's a solid top-up.

GUS A string of other Tasmanian sites have picked up a few millimetres too, and out on Mornington Island in Queensland's Gulf there's been 2.4 millimetres.

GUS The strongest wind gusts anywhere right now are down south, 76 kilometres an hour at Wilsons Promontory in Victoria and 69 kilometres an hour at kunanyi, Mount Wellington above Hobart.

GUS So it's a blustery, showery afternoon in the south-east, and quiet pretty much everywhere else.

[c01_verification]

GUS Quick check on how we did yesterday, marking our own homework against the Bureau's actual weather station observations.

GUS Of 48 towns checked for rain, we called it right at 41 towns and wrong at 7 towns,

GUS and our overnight low temperatures were out by about 1.8 degrees on average, biggest miss at Moree, about 6.4 degrees too warm.

[c02_mslp_fronts]

GUS Now the big picture, the highs and lows driving everything, because storms need a trigger, and that usually comes from a trough or a front.

GUS There's a strong high, 1028.8 hectopascals, over the Southern Ocean well south of Bunbury, and a weaker one, 1018.4 hectopascals, over the Coral Sea near Coffs Harbour.

GUS A low sits over western Queensland near Mount Isa, a pressure of 1012.9 hectopascals.

GUS Higher up, a trough is draped across the Tasman and Coral Seas, and the jet stream,

GUS the fast river of air that steers our weather, is running over 200 kilometres an hour out near New Caledonia.

GUS That upper trough is exactly what will help spark the bigger storms near Rockhampton and Gladstone over the weekend.

[c16_temp]

GUS The Bureau has heatwave warnings out today for parts of the north, and here I'll be careful and plain, because heat like this can be dangerous.

GUS There's an extreme heatwave warning for the Kimberley district in Western Australia, and a severe heatwave warning for the Daly, Arnhem and Carpentaria districts near Darwin, both issued yesterday afternoon.

GUS A severe heatwave tests the health even of people who normally cope fine in warm weather, an extreme heatwave is a step up again, hardest on the very young, the elderly and anyone working outside.

GUS There's also a severe heatwave warning for the Pilbara and North Interior districts of Western Australia, where our model has a top near 44.6 degrees inland.

GUS That same severe heatwave warning for the Pilbara and North Interior districts stays current through the weekend, so pace yourself if you're working outside in it.

GUS For the areas each warning actually covers, check bom.gov.au.

[c15_index_map]

GUS Fire danger next, and the number to know is the Forest Fire Danger Index, which rolls temperature, wind, dryness and available fuel into one score.

GUS In western Western Australia, remote country south-east of Karratha, that index reaches a value the Bureau calls extreme tomorrow afternoon, among the highest categories there is.

GUS Part of that score is the drought factor, how cured and ready to burn the grass and scrub are after recent weeks,

GUS here rated at the very top of the scale, as cured as it gets, based on actual rainfall records.

GUS So, the short version, extreme fire weather inland from Karratha tomorrow, in grazing and travelling country.

GUS There's also a moderate flood warning for the Balonne River to Surat, including the Balonne River at Warkon.

[c92_river_gauges]

GUS Now three flood warnings, all in outback Queensland's river country, all rated moderate by the Bureau.

GUS There's a moderate flood warning current for the Barcoo River downstream of Isisford, including the Barcoo River at Retreat.

GUS There's also a moderate flood warning for the Bulloo River downstream of Quilpie, including the Bulloo River at Thargomindah, with the Bulloo sitting at 4.91 metres at Autumnvale.

GUS That covers the Balonne River around Surat and at Warkon, the Barcoo River downstream of Isisford and at Retreat, and the Bulloo River downstream of Quilpie and at Thargomindah.

GUS The Balonne at Warkon is 8.42 metres and steady, the Barcoo system at Retreat Creek has jumped to 6.5 metres and is still rising, and the Bulloo at Autumnvale is 4.91 metres and steady.

GUS Elsewhere, the Wilsons River at Lismore in New South Wales is rising to 0.56 metres,

GUS the Latrobe at Rosedale in Victoria is rising to 1.93 metres, and the Torrens in Adelaide has crept up to 9.44 metres.

GUS None of those numbers mean a river is in flood, that's the Bureau's call, for the official flood warnings check bom.gov.au.

[c07_cape]

GUS Now the real severe weather story for the weekend, building off the central Queensland coast near Rockhampton and Gladstone.

GUS The air there is properly moist, dew point around 23 degrees, and precipitable water, the total moisture stacked through the atmosphere, about 41 millimetres, both on the high side for this coast.

GUS Think of storm fuel like the petrol in a tank, the warm, moist air a storm can feed on, forecasters call it CAPE,

GUS measured in joules per kilogram, and here it's around 1,900 joules per kilogram, a strong amount for this time of year.

GUS On its own, that stored energy doesn't make a storm, something still has to set it off, which is what we look at next.

[c08_skewt]

GUS Even with that much fuel, storms often need to punch through a lid, something called a cap,

GUS a layer of slightly warmer air above the surface that stops rising warm air before it turns into cloud, like a lid holding steam in a pot.

GUS This model sounding, basically a core sample through the air at one point, shows almost no cap here, so storms have an easy run upward once they get going.

GUS The trigger is that upper trough we looked at earlier, swinging through Saturday night into Sunday, lifting the moist, unstable air until storms fire, mainly overnight Saturday into early Sunday.

GUS Picture two zones, right where the trough meets the moist air offshore storms can be strongest, large hail and damaging wind possible, closer to the coast around Gladstone and Rockhampton it's more hit and miss.

[c12_index_map]

GUS Next, wind shear, how much wind changes speed and direction as you go up, because that decides whether storms stay as isolated showers or start to organise and spin.

GUS Through the lowest six kilometres here, shear is around 85 kilometres an hour, strong enough to support long-lived, organised storms, including ones that can start to rotate.

GUS Forecasters roll instability and shear together into a supercell number, near Gladstone it's high, so some storms could become proper rotating storms with large hail and damaging wind.

GUS That's a measure of the environment, not a guarantee any one storm rotates, so take it as the ingredients are there, not a sure thing.

GUS Short version for Rockhampton and Gladstone, a good chance of organised storms Saturday night into Sunday morning, large hail and damaging wind the main risks, some spots soaked, others missing out.

[c09_skewt]

GUS A similar storm signal is lining up Saturday night over the Tasman Sea about 50 kilometres south of Coffs Harbour in New South Wales, strong instability and a supercell number above four.

GUS It's sitting well offshore though, so coastal impacts around Coffs Harbour itself should be limited, mainly a system to watch rather than worry about.

GUS A southerly wind change is also due through there Saturday night, which could help spin any storms up a little more before they move away from the coast.

[c94_sounding_compare]

GUS One more tool before we head north, comparing two model soundings side by side over remote Gulf Country, basically two core samples through the air.

GUS On each, the line on the right is air temperature going up, the line on the left is dew point,

GUS where those lines sit close together the air is nearly saturated, where they're far apart it's dry.

GUS Over Normanton the moist layer reaches up to about 300 hectopascals, which is deep, fuel for heavy rain, over Halls Creek it only reaches about 600 hectopascals, a shallower layer.

GUS Storms are also possible overnight in that same remote country.

GUS This is also build-up season up north, the steady trade winds have swung around and been cut off, so instead of reliable rain you get hit-and-miss storms like these until the monsoon arrives in December.

[c90_events]

GUS A quick look at the weekend's big events, because nothing ruins finals day like not checking the forecast first.

GUS In Newcastle, Saturday evening's Rugby League World Cup semi-final has a real thunderstorm risk,

GUS gusts to 54 kilometres an hour, lightning there means play stops, so keep an eye on the sky if you're headed along.

GUS At Rosehill in Sydney, Ladies Day at the Everest Carnival Saturday also carries a thunderstorm risk, gusts to 53.

GUS At Flemington in Melbourne, Champions Stakes Day Saturday has a smaller storm chance plus rain, and the nearby Sandown 500 looks like getting a decent soak over the weekend.

GUS Pride Fairday in Perth on Sunday should be fine, just breezy, gusts to 48.

GUS Sunscreen and a poncho both earn their place in the bag this weekend.

[c02_mslp_fronts]

GUS Since this is meant to be our tropical cyclone update, here's an honest one, there's no official tropical cyclone anywhere near Australia right now.

GUS There's also a weak tropical low sitting over north-east Western Australia, about 250 kilometres south-west of Kununurra, bringing locally heavy rain but nothing organised yet.

GUS The European ensemble is flagging a couple of areas that might develop out over the Pacific well north-east of us next week,

GUS but the spread between runs is enormous, thousands of kilometres, and most stay nowhere near our coast.

GUS Nothing to act on here, just something I'll keep watching so you don't have to.

[c20_town_table]

GUS Time for the lap of the capitals, all eight cities, today's high, tomorrow's low and high, and the rain,

GUS each with its own number, because that's what actually affects your day, not what's happening out in the desert.

GUS Sydney, today's top 21.5 degrees and dry, tomorrow a low of 13.1 degrees and a high of 27.6 degrees,

GUS with about 2.9 millimetres of rain, enough to dampen the Everest Carnival but not wash it out.

GUS Melbourne, today topping out at 22.2 degrees with just 0.1 millimetres of rain, tomorrow a cooler low of 7.9 degrees,

GUS a high of only 13.6 degrees, and a proper soaking, about 5.1 millimetres of rain, jumpers back out, Melbourne being Melbourne.

GUS Brisbane, today's top 27.1 degrees and dry, with a low tomorrow of 17.9 degrees and a high of 31.1 degrees, staying rain free, a classic warm, muggy Brisbane day.

GUS If you're at the cricket nets in Brisbane this weekend, no excuses, it's shaping up glorious both days.

[c20_town_table]

GUS Rounding out the capital lap, the other four cities.

GUS Perth, today's top 24.9 degrees and dry, holding dry tomorrow too with a low of 16.1 degrees and a high of 21.9 degrees, Perth doing its usual thing, sunshine and a bit of smugness.

GUS Adelaide stays dry, next to no rain, with a low of 11.4 degrees and a high of 16.9 degrees tomorrow, good drying weather if you've got washing on the line.

GUS Canberra cools down noticeably, a low of 3.8 degrees and a high of 19.5 degrees tomorrow, grab a jumper for the morning dog walk.

GUS Hobart stays the coolest and wettest of the lot, a low of 2.3 degrees and a high of only 8.5 degrees tomorrow with another 4 millimetres of rain falling,

GUS that's a proper jumper-and-a-cuppa stretch down there.

[c18_model_compare]

GUS Now the weekend verdict for the places most people actually live, not just the places that look dramatic on a map.

GUS South-east Queensland, Saturday and Sunday look fairly quiet, light showers at most around Gympie and the Sunshine Coast, no organised storm signal yet for Brisbane itself.

GUS Nothing like a storm day based on today's numbers for the harbour city.

GUS Our capital down south stays dry and mild both days, no rain signal worth mentioning.

GUS Melbourne is the one to watch, showers likely Saturday building on that 5.1 millimetres we flagged, and that unsettled,

GUS showery pattern sticks around into next week, it's rain, not storms, based on what this signal can tell us.

GUS So of the four, Melbourne has the real wet weather coming this weekend, the others look dry to just patchy.

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.

[c20_town_table]

GUS Looking further out, days three through six, using one model's nine-day signal, so treat this as a guide, confidence drops the further out we go.

GUS In south-east Queensland, Wednesday the eleventh shows plenty of the stored storm energy we looked at earlier building up, but nothing obvious yet to set it off,

GUS so that's a chance that could fizzle rather than a promise of storms, by Thursday the signal shifts to a soaking with both methods agreeing on rain.

GUS Central and north Queensland run a similar story through the middle of next week, storm ingredients most days, whether something triggers them is the uncertain part.

GUS Up near Darwin, Monday through Thursday all carry that same pattern, big stored energy, uncertain trigger, typical for this time of year as the wet season tries to get going.

GUS None of this is a storm promise, it's the ingredients list, worth watching, and I'll update it in the next bulletin.

[c17_ens_prob]

GUS Overall confidence in today's forecast is high, I'd call it solid for this sort of pattern.

GUS That's mostly down to the models agreeing well on rain signals at most of our storm hotspots and on the low-pressure positions over the next two days, the shakier parts are further out in time.

GUS If that trough ends up tracking a touch further north or south than today's guidance, the whole storm placement near Rockhampton and Gladstone could shift, so I'll keep watching it through tomorrow's bulletins.

[c20_town_table]

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

GUS I'm back with the next bulletin tomorrow morning.

GUS If you've got a weather question, or want to tell me what the sky's doing where you are, put it in the comments and I'll get to as many as I can.

GUS Thanks for watching, I appreciate you spending part of your afternoon with me.

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

GUS Gus's Weather is a PandaVision production.