November 12, 2024
It’s been a stormy couple of weeks across Southeast Queensland, and while severe storms have been frequent, tomorrow is looking particularly intense. The potential for severe storms brings a heightened risk of large hail and damaging winds, with isolated supercells possibly producing destructive winds and giant hail. Brisbane, the Gold Coast, Sunshine Coast, and surrounding areas are in the firing line.
Forecast rainfall from G3 for tomorrow (Wednesday). Source: MetCentre
Key Factors Driving Storm Development
A shortwave upper trough responsible for recent shower and storm activity in central Australia is tracking eastward and expected to lie across NSW and southern Queensland. This will combine with a warm, humid, and unstable airmass to further destabilize the atmosphere, resulting in moderate to strong levels of instability.
G3 500mb temperatures showing the upper trough tracking into NSW tomorrow (Wednesday). Source: MetCentre
Wind shear will be highly conducive to severe storm development, with 40-50 knot westerly winds at 500mb combining with 15-20 knot N to NE winds near the coast, enhanced by the seabreeze. This setup will see bulk shear approaching 50-55 knots—more than sufficient for supercell formation.
Forecast sounding for Brisbane at 4pm tomorrow afternoon showing moderate to strong levels of instability (CAPE ~2500j/kg), strong mid-level wind shear and a deep NE feed in the lower atmosphere. Source: MetCentre
Timing and Potential Variables
As with many high-end severe storm setups in eastern Australia, some factors will ultimately influence tomorrow’s storm potential. One key factor is cloud cover—clouds drifting in from central Australia may limit the heat required to fuel storms, though they are expected to be less dense than today’s cloud cover.
Large amounts of cloud are tracking across, though cloud cover should be thinner tomorrow compared to today. Source: MetCentre
The timing of convection is another factor. Given the strength of the upper trough, expect shower and storm activity to initiate on the northeastern edge across parts of inland northeastern NSW and inland Southeast Queensland as early as mid-morning. This early development could potentially detract from severe potential, but current model data suggests storms could intensify as they move into southeastern Queensland and northeastern NSW from early to mid-afternoon.
Interestingly, despite strong westerly wind shear, models indicate a northeastward track for the strongest storms—a sign of the intensity potential for tomorrow’s activity.
Forecast rainfall loop tomorrow showing storms tracking northeast. This is consistent across numerous forecast models that show similar patterns. Source: MetCentre
Safety Tips for Severe Weather
All modes of severe weather are possible tomorrow (damaging winds, large hail and heavy rainfall in particular). However some storms could bring destructive (>125km/h) winds and giant (>5cm) hail. This will be more isolated but given metropolitan areas are at threat, these have the potential to produce significant damage.
While severe storms are common in Brisbane and surrounds at this time of year, tomorrow’s setup brings a heightened risk of significant damage and possible loss of life. Here are some tips to help you stay safe:
Plan ahead: If you need to go out, try to do so in the morning, as the highest chance of storms will be during the afternoon.
Protect your vehicle: Park your car under shelter if possible, but avoid parking under trees. Trees provide minimal protection and falling branches can be deadly in strong winds.
Avoid flooded areas: With recent shower and storm activity, catchments are already wetter than usual, so flash flooding could be a concern. If it’s flooded, forget it.
Monitor warnings and the radar: Stay updated on weather warnings and radar images, especially during the afternoon.
Stay clear of fallen powerlines: Report fallen powerlines immediately to Energex.
Shelter indoors if needed: In the event of a severe storm, move away from windows and shelter in the smallest, interior room of your house, such as a pantry, laundry, or bathroom.
Severe Storms to Also Extend Well into Eastern NSW
The highest potential for severe storms will lie across the NE NSW and SE QLD region - but storms with possible damaging winds and hail could extend right down through eastern NSW thanks to a trough extending south and interacting with the cold air from the approaching upper trough.
Forecast rainfall, this is heaviest around NE NSW and SE QLD where the strongest storms are expected, but rainfall extends down across eastern NSW. This is coinciding with more moderate levels of instability and some storms are likely to become severe over eastern NSW also. Source: MetCentre
SE QLD Could See More Severe Storms on Thursday
Unfortunately, more severe storms may follow on Thursday for southeastern Queensland as a southeast change moves through the area. However, Thursday’s activity should be more isolated, with severe potential likely to reduce depending on the position of the dryline relative to the coast.
Thursday's setup is contingent on the dryline not pushing too far to the coastline or this may reduce the potential for further storms. Source: MetCentre
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