Flood, heatwave and storm watch across | Australia weather Sun 1 Nov morning | Gus's Weather

Flood, heatwave and storm watch across Australia, Sunday 1 Nov

[c06_radar_now]

GUS G'day, I'm Gus, and this is your morning bulletin for Sunday the first of November.

GUS First thing to know, there's heavy rain sitting over Sydney and inland New South Wales right now,

GUS flood warnings are current on several inland Queensland rivers, and a real storm risk is building for later this week.

GUS If you're watching, tell me in the comments what the sky's doing where you are.

GUS It's about 6 am in Brisbane at the time this is uploaded.

GUS This is the Bureau of Meteorology's real national radar, not a model picture, the whole country on one map, and the newest scan is about 10 minutes old.

GUS The heaviest rain on it is very heavy rain north-east of Mudgee in New South Wales, covering a huge area, something like 12,000 square kilometres.

GUS There's also a small but top of the scale cell south-east of Port Pirie in South Australia,

GUS heavy rain east of Moree in New South Wales, and very heavy rain near Katherine in the Northern Territory.

GUS For the capitals, Sydney has heavy rain, Perth, Melbourne, Canberra and Brisbane light rain, and Adelaide, Hobart and Darwin are clear.

GUS The model's own simulated radar only had one small cell for this hour, well out in the Tasman Sea, so it's missed the real rain near Sydney and inland New South Wales.

GUS Trust the Bureau's radar over the model picture this morning.

[c07_lightning_now]

GUS Right, the lightning picture, my favourite light show that doesn't need a power bill.

GUS It shows where storms are actually discharging electricity, not just where it's raining, over the whole country in the last six hours.

GUS The Blitzortung lightning network, a volunteer network of ground detectors, has picked up over 8,000 strikes in the last six hours across Australia, with about 700 of those in just the last hour.

GUS The busiest cluster is actually out to sea, about 370 kilometres south-east of Wollongong, and it's easing off.

GUS Closer to people, there's a cluster about 120 kilometres south-west of Tamworth holding steady, and another near Bathurst, also steady, both part of that same wet patch we just saw on radar.

GUS There's lightning near Roma in Queensland too, a smaller cluster about 60 kilometres west of the town.

GUS None of this tells you if anywhere is safe or in danger, that's what the Bureau's warnings are for.

[c05_obs_now]

GUS Numbers don't lie, so before any forecast, here's what's actually been measured since 9 am this morning, by Bureau of Meteorology weather stations around the country.

GUS The wettest spot anywhere is Mount Read in Tasmania, with 57.6 millimetres of rain since 9 am, a proper soaking up on that mountain.

GUS Luncheon Hill in Tasmania and Mount Buller in Victoria have both had over 20 millimetres, and Cape Naturaliste in Western Australia has had almost 21 millimetres.

GUS Back over that same stretch of New South Wales, it's raining hardest right now around the Hunter Valley, with Gunnedah picking up nearly 8 millimetres of rain in just the last hour.

GUS The strongest wind gust measured anywhere so far is 61 kilometres an hour, at Tamworth Airport, the same town where we just saw lightning holding steady.

GUS That's where rain has fallen, not where it's going. Credit to the Bureau of Meteorology for all of that.

[c04_satellite]

GUS Right, the satellite can see things the radar can't, let's have a look.

GUS It measures how cold, and therefore how high, storm tops are, and that tells us how strong a storm really is, plus it can see storms where there's no radar at all.

GUS This is the real Himawari satellite picture from about 4 am, not a model.

GUS The biggest storm top right now is inland, about 30 kilometres west of Tamworth, with cloud as cold as minus 60 degrees Celsius, that's a genuinely strong storm, and Tamworth is a populated area.

GUS There's another one out over the Tasman Sea, well south-east of Wollongong, cold as minus 62 degrees, but that one's well out to sea.

GUS Here's the thing, the model's version of this hour completely missed both of those storms,

GUS it's running behind the real atmosphere this morning, so lean on the satellite and the radar, not the model detail, for right now.

[c06_radar_now]

GUS So the headline for today, it's a flood and heat watch day across the north and inland Queensland,

GUS catastrophic fire danger out west, and from later this week a real storm signal builds for inland Queensland and the Top End.

GUS We'll start with how yesterday's forecast went, then the warnings, then the ingredients behind today's storms.

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

[c01_verification]

GUS Quick check on how yesterday's forecast actually verified against independent weather station data, because you should know how far to trust me.

GUS My daytime highs were off by an average of 1.8 degrees yesterday,

GUS a bit warm in places like Port Hedland where I was 5.8 degrees under, the European model was off by more, 2.6 degrees on average.

GUS On rain, over the last seven days I've called it right about 82 per cent of the time across the country, a solid track record, not a perfect one.

[c92_river_gauges]

GUS The Bureau of Meteorology has a Major Flood Warning for the Condamine River downstream of Oakey Creek to Cotswold,

GUS including Chinchilla, where the river is near 8.2 metres, high enough to isolate properties and cut roads.

GUS There's a Moderate Flood Warning for the Barcoo River at Blackall, downstream to Isisford, near 4.1 metres,

GUS another for the Bulloo River at Quilpie near 3.6 metres, and the Warrego through Charleville and Cunnamulla is also running high.

GUS A severe heatwave warning is current for Darwin and the Top End, meaning several days of unusually high heat.

GUS The Bureau also has a Severe Heatwave Warning for the Peninsula and Gulf Country Districts of Queensland, including Normanton,

GUS where daytime temperatures are expected near 41 degrees for several days, hard on health for people and stock.

GUS And there's a Severe Heatwave Warning for the Kimberley and North Interior Districts of Western Australia,

GUS where temperatures are forecast to reach about 42 degrees for several days, tough on anyone working or travelling out there.

GUS Looking at actual river levels from the Queensland Government, the Fitzroy River at The Gap is at 6.41 metres and still rising,

GUS up 0.17 metres in the last day, while the Logan and Mary Rivers further south-east are falling.

GUS The ground in south-east Queensland is already very wet, about 48 millimetres of rain in the past week there against a usual 18 millimetres,

GUS so fresh rain runs off fast instead of soaking in, using data from SILO, the Queensland Government's climate records.

GUS Across the model ensemble there's about a 67 per cent chance somewhere in the country picks up 50 millimetres of rain in 24 hours over the next couple of days,

GUS so the flood risk on those already full inland Queensland rivers isn't going away soon.

[c02_mslp_fronts]

GUS Now the big picture, the highs and lows driving all this, because a forecaster always checks the pattern before the details.

GUS There's a low pressure system over the Great Australian Bight today, near Whyalla in South Australia, down to 1004.5 hectopascals, and that's the system that pushes a change and showers into Victoria by tomorrow.

GUS A high near Canberra, 1018.3 hectopascals, is keeping south-east New South Wales dry.

GUS There's also a shallow low near the Coral Sea, about 110 kilometres north-east of Coffs Harbour, at 1013.7 hectopascals, and that's the same spot holding the moist, unstable air we're about to look at.

GUS There's also a marine warning area over the Coral Sea, about 100 kilometres north-east of Coffs Harbour, with rough seas and strong winds affecting shipping and small craft off the Mid North Coast.

GUS Higher up, around 5500 metres, there's a trough running from south-east Western Australia out into the Bight,

GUS with a strong, fast jet stream behind it, close to 280 kilometres an hour, currently over far western New South Wales.

GUS That jet is what will help kick the stronger storms off over Victoria tomorrow.

[c07_cape]

GUS Let's look at the ingredients for storms, starting with moisture and energy, because a storm needs moist air and something unstable before it can even think about forming.

GUS That same low we marked near Coffs Harbour is sitting over proper moist, tropical-feeling air, the dewpoint there is about 20 degrees.

GUS Meteorologists measure the energy a storm can feed on, they call it CAPE. Think of it like the petrol in a storm's tank.

GUS Over that patch of Coral Sea it's about 1700 joules per kilogram, which for this time of year is a decent tank, enough to build tall thunderstorms.

GUS That storm fuel is closest to towns like Lismore and Grafton inland, and Yamba on the coast.

GUS There's even bigger storm fuel for tomorrow, over 2400 joules per kilogram near Kununurra, and 3100 joules per kilogram near Normanton in the Gulf Country, among the biggest tanks anywhere in the country today.

GUS Energy on its own isn't a storm though, something still has to set it off, and that's what we check next.

[c09_skewt]

GUS This is a model sounding, think of it as a core sample through the air above one spot, here it's the air out near that Coral Sea storm energy, north-east of Coffs Harbour.

GUS First, the lid. That's a layer of warmer air sitting above the surface that acts like a lid on a pot and stops warm, moist air below from rising.

GUS Out there it's weak, about minus 117 joules per kilogram of resistance, basically an easy lid to lift.

GUS With a lid that weak, once the sun heats the ground through the day, that moist air can break through on its own, storms should start firing through the afternoon and evening.

GUS A weak ridge of drier air pushing up the coast from the south is meeting that moist tropical air offshore,

GUS and where the two meet is where storms will be strongest, roughly from the Mid North Coast up toward the border.

GUS Homework for today, if you're anywhere between Coffs Harbour and the border this afternoon, watch the northern sky for cumulus towers building tall and dark, that's your sign the lid's broken and storms are starting.

[c11_shear]

GUS Now the wind shear, that's how much the wind changes speed and direction as you go up through the atmosphere, think of it like flicking a spinning top instead of just pushing it.

GUS Out near that Coral Sea storm energy, the shear through the lowest six kilometres is strong, about 111 kilometres an hour of change.

GUS Strong storm energy plus strong shear like that is the recipe for supercells, storms that build a rotating updraft and can last for hours instead of fizzling in twenty minutes.

GUS The hail index out there is elevated too, so some of these storms could produce hail big enough to dent a car.

GUS The Bureau would call the rotating ones severe thunderstorms, what we call rotating storms here, storms that can start to spin, with the possibility of destructive winds too.

[c12_index_map]

GUS This next map is called a Supercell Composite, it bundles stored storm energy, wind shear and spin into one number, so forecasters can spot where a rotating storm is most likely.

GUS The highest number anywhere in the country for Monday is out near Bendigo in Victoria,

GUS about 70 kilometres north-west of town, a high supercell composite value, a strong signal for a storm that can start to spin.

GUS But there the storm energy itself is modest, only around 600 joules per kilogram, a much smaller tank than what's sitting near the coast up in New South Wales.

GUS That's a good lesson, a high spin number without much fuel in the tank often means a storm that rotates but doesn't get very tall or dump much rain, worth watching into Monday morning.

[c18_model_compare]

GUS Let's check how the American GFS, the European model and the European AI model line up on rain near that Coral Sea storm energy, for the 24 hours ending midday today.

GUS They're close, the American model says 3.8 millimetres, the European model also 3.8 millimetres,

GUS the European AI model a touch higher at 4.8 millimetres, so the models broadly agree there's some rain, just not a huge amount on average across the area.

GUS When models agree like that I trust the forecast more, the main uncertainty is exactly which town under that cloud gets the heaviest burst.

GUS I'm not leaning either way here, the numbers are tight enough to call it genuine agreement.

[c15_index_map]

GUS The fire danger index, called the FFDI, combines heat, wind, dryness and available fuel, the higher the number the more dangerous any fire would be.

GUS The worst of it today is in far western New South Wales, about 200 kilometres north of Mildura, near Broken Hill,

GUS where the index reaches catastrophic levels, with temperatures near 34 degrees, humidity down near 9 per cent, and gusts to 75 kilometres an hour.

GUS There's also extreme fire danger further west again, near Coober Pedy in northern South Australia, in similarly hot, dry, windy conditions.

GUS Catastrophic means any fire that starts would be extremely difficult to control, so if you're out that way, know your fire plan and follow local advice.

[c90_events]

GUS A quick look at today's big outdoor events, using the forecast at the actual venue.

GUS Sydney's Sculpture by the Sea and three Rugby League World Cup matches carry a storm risk today, so shelter if lightning starts.

GUS Melbourne's Cup Day on Tuesday looks mostly dry at Flemington itself, though the week ahead signal shows good rain chances either side of it.

GUS Nothing serious weather-wise for the other events on the board this week.

[c20_town_table]

GUS Now the lap of the capitals, today's daytime high plus tomorrow's overnight low and high, and the rain for each in millimetres, plus what to do for the big five.

GUS Brisbane, a top of 28 today, tomorrow's low 19, high 30, about 4 millimetres of rain today and 5 tomorrow, nothing to worry about.

GUS Maybe keep a brolly handy for an afternoon shower, this is Brisbane after all.

GUS Sydney, a top of 24 today, tomorrow's low 20, high 25, about 3 millimetres of rain today easing to just over 1 tomorrow, pack an umbrella today given that storm risk near the coast.

GUS Melbourne, a top of 21 today, tomorrow's low 11, high 21, about 4 millimetres today, barely anything tomorrow.

GUS A fairly ordinary Melbourne day, happy to have the barbecue on this evening.

GUS Perth, a top of 20 today, tomorrow's low 13, high 21, around 3 millimetres today, barely anything tomorrow, good drying weather coming for the washing.

GUS Adelaide, a top of 23 today, tomorrow's low 12, high 21, almost no rain today, about 3 millimetres tomorrow, nothing to worry about either day.

GUS Canberra, a top of 24 today with about 8 millimetres of rain, then dry tomorrow, low 9, high 23.

GUS Hobart, a top of 17 today with about 4 millimetres of rain, tomorrow a low of 9,

GUS a high of 17, barely any rain, that's a proper jumper and a cuppa sort of day down there.

GUS Darwin, a top of 34 today, tomorrow's low 27, high 34, with a couple of millimetres of rain both days.

[c20_town_table]

GUS You've just had today's and tomorrow's numbers for every capital, now here's a different question, the storm verdict for the coming Friday and Saturday in the south-east.

GUS Brisbane looks quiet both days, no real storm energy flagged yet, just a chance of a shower.

GUS Sydney looks fairly quiet too, light rain at most, nothing pointing to storms yet.

GUS Canberra looks dry and settled both days.

GUS Melbourne is the one to watch, Friday looks quiet, but Saturday has both the American and European models agreeing on some decent rain.

GUS This is a signal five and six days out, it's a guide, not a locked-in forecast, and it'll keep being updated.

[c19_plume]

GUS Now the week ahead, days two through eight, this comes from a European model's nine day rain forecast,

GUS it only tells us about rain, nothing about thunder or hail, so I can say wet, but not storms, from this bit alone.

GUS In south-east Queensland, Tuesday looks wettest, with a soaking for the Sunshine Coast and Gold Coast, then showers return later in the week.

GUS In Victoria and Tasmania, Monday tomorrow is already looking showery for Melbourne, Geelong, Ballarat and Bendigo, then there's a bigger, heavier signal for Friday the sixth of November, especially around Melbourne.

GUS Separately, I've also got a longer ingredients outlook from the American model, looking at the stored storm energy we looked at earlier and pressure patterns, out to about a week.

GUS For central Queensland, around Rockhampton and Emerald, Thursday through Saturday shows plenty of that stored storm energy building,

GUS over 2000 joules per kilogram by Friday, but nothing obvious yet to trigger it, so there's a real chance it just fizzles.

GUS The Top End shows even bigger numbers, but the models disagree on what sets it off.

GUS Why did the trough skip its appointment in central Queensland? It left its spark at home. Sorry, not sorry.

GUS Confidence on all of this drops the further out you go, days three and four are a decent guide, five to eight are only a signal,

GUS small errors in the model can double every day or two, so check back, I'll update this every bulletin.

[c14_rain_wind]

GUS Overall confidence in today's picture is high, about 76 out of 100.

GUS That's because the models agree well on where the quiet, dry areas are, and reasonably well on the low pressure system crossing the south,

GUS it's the exact placement of Monday's storms in Victoria and the Top End I'm least sure about.

GUS If that Victorian trough ends up a bit further east or west than forecast, the heaviest rain and any hail could land in a different spot, so don't lock in an exact town just yet.

[c06_radar_now]

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 get to as many as I can during the day, and let me know what the sky's doing wherever you are too.

GUS Thanks for watching, look up now and then, the sky's the best show in town.

GUS Gus's Weather is a PandaVision production.