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Outbreak Weather, Perth (2025)

20/12/2025

Severe thunderstorms are Likely across parts of South-Central New South Wales and Northeastern Victoria during the afternoon and evening hours.

Primary hazards include Damaging to Destructive Wind Gusts, Large Hail and a couple of Tornadoes.

A H5 trough will overspread southeastern Australia during Sunday Afternoon, becoming slightly negatively tilted as it approaches the region. By early afternoon, surface cyclogenesis is expected with a 995mb surface low developing over north-central Victoria, while an attendant cold front advances eastward into a moist and unstable air mass.

Ahead of the front, an axis of rich boundary layer moisture will extend from Northeastern Victoria northward into central New South Wales, with surface dewpoints near 22-23°C.
Diurnal heating and Large-scale ascent associated with the approaching trough will support the development of MLCAPE around 1200J/kg by afternoon hours.

Kinematic fields will be strongly supportive of organised severe convection. 0-6 km Deep Layer Shear of 60-70 kt is forecast in Northeastern VIC as the upper trough translates eastward.
In the low levels, a strengthening NNW H85 jet of around 45kts is expected ahead of the cold front, resulting in backed low-level wind profiles. This is resulting in hodograph curvature and effective SRH of 150-220m2s2.

Latest CAM runs have suggested a Strong MCS is likely to develop along the Cold Frontal boundary spreading into New South Wales, with possible Semi-discrete/line embedded Supercells along the Periphery.

The primary Severe hazard is likely damaging to destructive Straight-line Wind Gusts. Large hail will also be possible, especially with any embedded supercell structures, though may be limited by modest mid-level lapse rates and a displaced cold pool. Additionally, given the strong low-level shear and Hodograph curvature, a conditional risk for a couple of Tornadoes exists, mainly within QLCS mesovortices or embedded supercells, particularly across northeastern Victoria and the southern New South Wales border region.

17/12/2025

Tornado Scar Discovery- East of Gympie, QLD

On November 24th 2025, a Left-moving Supercell developed tracking Northeast toward Rainbow Beach, QLD, to the East of Gympie.

This included a pronounced Hook Echo, a well-defined inflow notch, and velocity couplet indicative of a low-level Mesocyclone.

Estimated Peak VROT=37.75m/s (69.49kts) 700m AGL

Radar data at the time revealed a strong velocity couplet, indicating the presence of a low-level mesocyclone. However, due to abscene of the nearby radar's dual-polarization capability, tornado confirmation remained uncertain.

Recent analysis using high-resolution Sentinel-2 satellite imagery has now indicated that this supercell did, in fact, likely produce a Tornado.
Clear signs of deforestation and a distinct erratic damage, path with possible deviant motion, aligned with the storm’s trajectory, provides visual evidence of Tornadic activity.

The identified track path appears to be around 10km in length.
Pictured are the Radar images and before-and-after satellite images from November 24th and December 4th. The damage track is evident within the forest from the shoreline and reveals the tornado’s path in which the supercell passed over.

13/12/2025

Severe Thunderstorms are possible across the Perth Metropolitan area and the Southwest Land Division of Western Australia during Sunday afternoon and evening.

Elevated, high-based convection is expected to develop across the Perth Metro and much of the Southwest Land Division during the afternoon hours.

A surface trough is forecast to become positioned just offshore as a ridge builds into the Great Australian Bight. Moisture advection southward ahead of this feature will support moderate elevated instability, with peak MUCAPE values of approximately 1200-1400 J/kg developing across southwest Western Australia.

The offshore trough will act as the primary synoptic-scale forcing mechanism for thunderstorm initiation during the afternoon. Although deep-layer shear is expected to remain weak (20–25 kt), the environment should support multicellular convection, with limited storm organisation.

A deep, well-mixed boundary layer is anticipated given surface temperatures reaching the low 40s. Resultant steep low to mid level lapse rates near 8.5°C/km or greater, and large temperature-dewpoint spreads are yielding inverted-V thermodynamic profiles on forecast soundings. This environment appears favourable for Damaging Convective Straight line Wind Gusts, driven by Dry Microbursts and high DCAPE values.

The latest 18Z ECMWF Lightning flash density guidance indicates a high degree of Lightning activity with developing storms, while recent CAM guidance suggests scattered to widespread convective coverage across southwest WA.

A Dangerous environment could develop, given the combination of dry low-levels, strong downdraft potential, frequent lightning, and hot surface conditions. This environment will be favourable for New Fire ignitions and Rapid Fire spread, particularly with any Thunderstorm outflows.

Thunderstorm activity is also a marginal possibility on Saturday afternoon, although is likely to remain isolated, and more probable within the Northern extent of the SWLD.

07/12/2025

Severe thunderstorms are possible across northeastern New South Wales and southeastern Queensland this afternoon and evening.

MCS complex clusters and a couple of Isolated Supercells are possible across the region.

A confined axis of instability is expected to develop over northeastern NSW during the afternoon, where surface dewpoints may locally reach 24-25°. More broadly, slightly lower dewpoints will extend along the coastal corridor from NENSW into Southeast Queensland. Within this environment, MLCAPE is forecast to peak around 1200-1400J/kg.

Aloft, the eastward progression of a mid-level trough near the NSW/VIC border will contribute to enhanced westerly flow, supporting 0-6 km bulk shear around 45kt across NENSW and the southern QLD border region.
This shear environment should support organised convection, including supercells, consistent with the latest 00Z CAM guidance showing isolated development in northeastern NSW during the afternoon.
The environment could also locally become more supportive of organised convection by the arrival of a sea-breeze boundary during afternoon hours.

Forecast uncertainty remains regarding the magnitude of severe hazards, particularly given Global Model forecasts of modest 700–500 mb lapse rates. However, lower level lapse rates are expected to be slightly steeper, suggestive of damaging straight-line wind gusts as the primary hazard.
Nonetheless, large to very large hail cannot be ruled out with any discrete, more robust updrafts, supported by largely unidirectional , straight-line hodographs, and adequate buoyancy above the HGZ Isotherms.
Later in the period, upscale growth appears likely, with multiple MCS clusters expected to develop and track northeastward through the evening.

02/12/2025

A defined contrast in different air-masses was evident over Australia yesterday with two notable records including Canberra's overnight temperature of -0.3°C. This is the First time a Sub-Zero Temperature has been recorded in Canberra during Summer.

In contrast, Perth recorded its Hottest Start to Summer on Record, with the December 1st temp reaching 39°C. Some of the outer Metro Suburbs recorded temperatures into the low 40s, with the air-mass spanning both through the Mid-West and South West.

Temperature Anomalies across Southeastern Australia were around 5-15° below climatological average for this time of year. Two primary synoptic driving factors were responsible for this well defined thermal gradient.

Developed Ridging near the Great Australian bight, in combination with West-Coast Surface troughing facilitated strong easterly to northeasterly temperature advection into Western WA, drawing in a hot, continental airmass.

Meanwhile, in southeastern Australia, the passage of a vigorous cold front induced a meridional flow regime, channeling a significantly colder airmass across eastern SA, Victoria, and southern NSW. This was supported by post-frontal cold advection, maintaining below-average temperatures across the region. Which also resulted in Snow-Fall across the Higher elevations.

29/11/2025

Severe Thunderstorms are likely across Southeastern Queensland and the NE NSW Border this afternoon and evening.

Isolated Severe Thunderstorms will be possible, with hazards including large hail and damaging to destructive straight-line wind gusts.

Morning satellite imagery shows a broad area of upper-level cloud over southeastern Queensland shifting eastward. Current guidance indicates continued clearing through the late morning. Though it remains unclear, the degree of downstream effects this may have for forecast convection during this afternoon.

Aloft, a low-amplitude, negatively tilted mid-level trough will track across the VIC/NSW border during the morning before moving offshore by the afternoon. Resultant deep-layer shear across SEQ is forecast to reach 45–50kt, supportive of organised convection.

A corridor of rich boundary-layer moisture is established across SEQ, with dewpoints expected to reach 23-24°C. MLCAPE values near 1500 J/kg are forecast, with the instability axis shifting eastward toward the coast through late afternoon and evening. Although becoming more confined, peak instability is expected to occur slightly after peak diurnal heating. Mid-level lapse rates will be modest although adequate for robust updrafts.

PWAT values of 50-55 mm and freezing levels around 4.5km suggest that very large hail is less likely, as a result of potential rain entrainment. However, large hail remains possible within sustained supercells, supported by sufficient buoyancy. Damaging to destructive wind gusts will also be possible with any organised storm structures.

27/11/2025

Scattered Severe Thunderstorms are expected across portions of Southeastern Queensland and northeastern New South Wales this afternoon and evening.

A Few Supercells will be possible, capable of producing Large to Very Large Hail (Potentially Giant) and Damaging to Destructive Straight-line Wind Gusts.

A complex zonal flow regime, featuring multiple eastward-moving mid-level troughs and embedded speed maxima, will contribute to a broad corridor of enhanced mid-level flow spreading into southern Queensland through the afternoon. Resultant 0-6 km bulk shear of 35-40kt will be supportive of organized convection, including supercells.

Thermodynamic profiles from recent ACCESS-G/C soundings indicate a well-defined elevated mixed layer (EML) with steep mid-level lapse rates of 8-8.5°C/km. Relatively minimal CINH is associated with the EML Base.
Strong instability is evident across the region, with MLCAPE around 2500J/kg and surface dewpoints possibly exceeding 25°C.

Within this environment, any storms that develop will be capable of producing significant hail, driven by strong buoyancy, steep lapse rates, and largely unidirectional hodographs. Hail sizes approaching 10cm appear possible with developed supercells.

Notably there are some concerns with this setup, including relatively warmer mid-level temperatures, this however still appears to support Hail growth, with substantial buoyancy above the HGZ isotherms. There is also concern regarding a late-afternoon eastward recession of the instability axis, which may confine the most favorable environment closer to the coast. Additionally, latest CAM guidance varies considerably in storm coverage, adding uncertainty to convective initiation and coverage.

26/11/2025

Extreme to Catastrophic Fire Weather is forecast in parts of NSW today for the first time in two years.

Dangerous Fire Weather conditions will develop across the Central West Plains, including the Dubbo and Parkes areas, where Catastrophic Fire Danger is expected. Surrounding this zone, Extreme Fire Danger is forecast for 10 neighbouring districts, including the Sydney Metropolitan area.

A hot and dry airmass is being advected across the region by strengthening northwesterly winds, with surface temperatures expected to reach the mid-high 30s. Across the Central West Plains, 10m sustained winds are likely to approach 40km/h, driven by the eastward progression of a cold front scraping the Victorian border. Relative humidity values are forecast to fall to around 13–14%, and peak wind gusts may reach 70–90km/h.

This combination of Heat, Low Humidity, and Strong Winds will create conditions supportive of Rapid, Dangerous, and Erratic fire behaviour. Any ignitions will spread quickly and will pose a significant threat to Life and Property. Recent Lightning activity across the region also raises the potential for smouldering Lightning-strike fires to escalate rapidly under today’s conditions.

Extreme caution is advised. Stay up to date with information from local emergency services.

24/11/2025

Softball Size Hail Smashing the Ground and Water near Wynnum, QLD this afternoon as multiple Semi-discrete/line embedded Supercells produced Giant Hail.

24/11/2025

Scattered Severe Thunderstorms are likely across Southeastern Queensland this afternoon and evening.

Supercells capable of producing severe hazards are possible, with potential hazards including large to very large hail (possibly Giant) and damaging to destructive straight-line wind gusts.

A pair of negatively tilted mid-level troughs, located to the south and east of the country, will be situated between a northerly mid-level ridge this afternoon. This will promote a broad belt of southwesterly flow aloft across eastern New South Wales and Queensland by 06Z. Aloft, H300 heights will become broadly diffluent, with a small region of enhanced ascent over southeastern Queensland.

At the surface, a diffuse surface trough will extend across the NSW/QLD border, while a dryline will be draped to the west of Toowoomba, extending in a NW-SE orientation. Near coastal areas, boundary layer dewpoints will be in the range of 21-23°C, which is expected to yield 1500-2000 J/kg of MLCAPE during the afternoon hours.

Low-level lapse rates will be particularly steep this afternoon, extending to the mid-levels (925-600mb). These LRs are significantly high and very steep around 8.5°C/km)
Latest ACCESS soundings indicate that some areas will experience an increase in temperature/dewpoint spreads during the afternoon. Combined with 45-50 kts of 0-6 km deep-layer shear, the threat for damaging wind gusts (potentially reaching destructive criteria) exists. Additionally, the threat for very large to Giant Hail exists with significant hail sizes (8cm+) possible due to strong buoyancy aloft and very steep lapse rates.

Initiating Supercells could locally enhance in severity, potentially becoming surface-based by the arrival of a sea breeze boundary during the mid-afternoon hours.

23/11/2025

CHECKOUT THE CORKSCREW MESOCYCLONE ON THIS SUPERCELL NEAR BYRON BAY, NSW! WOW!

23/11/2025

A Large Bow Echo moved through Southeastern Queensland this morning, tracking to the northeast.

A Bow Echo is a type of mesoscale convective system (MCS) characterised by a line of convection that begins to bow outward on radar reflectivity. This bowing is caused by strong forward propagation of the convective line, driven primarily by the development of a Rear Inflow Jet. As the RIJ strengthens, it descends toward the surface and accelerates the forward surge of the convective line.

On Radar velocity data, an area of enhanced velocities immediately behind the apex of the bow is an indicator of a strengthening rear inflow jet. This signature often corresponds to the region of greatest forward surge and the highest potential for damaging winds.

Bow echoes are commonly associated with Damaging Straight Line Wind Gusts. When bow echoes become particularly long-lived, expansive, and produce widespread, continuous, and non-tornadic damaging winds meeting specific criteria, they are classified as "Derechos".

Outbreak Weather

20/12/2025

17/12/2025

13/12/2025

07/12/2025

02/12/2025

29/11/2025

27/11/2025

26/11/2025

24/11/2025

24/11/2025

23/11/2025

23/11/2025

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