October 8, 2024
An outbreak of severe storms is likely across the southeast quarter of the state during today and tomorrow. While the most dangerous storms will likely occur tomorrow (Wednesday), these storms are expected in less populated areas (outside of the more populated Southeast Coast region).
ACCESS G next 2 days rainfall forecast showing extensive rain, showers and storms possible across the southeast quarter of the state. Source: Weatherwatch MetCentre.
Isolated Severe Storms Possible Today
Today's storm development hinges on the placement of a dryline boundary currently lying through southern inland Queensland. Drylines often initiate storms east of the boundary but can reduce the chance of storms occurring when they move too close to the coastline.
There is higher confidence in more humid (and thus, more unstable) conditions over the northern half of the Southeast Coast region (north of Brisbane), as well as the Wide Bay & Burnett and northern Darling Downs. In these areas, storms are more likely, with some potentially becoming severe and bringing damaging winds and large hail.
ACCESS G dew point and Lifted Index forecast. Storms cannot form where the air is too dry. Source: Weatherwatch MetCentre.
The "X-Factor" today is the southeast change moving through northeastern NSW and the southern half of the Southeast Coast. Storms here will be more isolated, so the chance of a storm affecting any given location is lower. However, any storms that do develop are likely to be severe, with large hail and damaging winds remaining possible.
Forecast soundings for Sunshine Coast vs NE NSW. Sunshine Coast contains higher instability but weaker wind shear, NE NSW contains weaker instability (and stronger cap), but much better shear and this will be the trade-off between the two areas today. Source: Weatherwatch MetCentre.
ACCESS C rainfall today. Convection is more favoured north of Brisbane, but the isolated storms to the south may still be severe. Source: Weatherwatch MetCentre.
Potentially Dangerous Storms Tomorrow: Ridge Cradled Trough
Tomorrow’s setup is far more concerning. While it will affect less populated regions, it still poses a serious threat to towns and communities. The "Ridge Cradled Trough" (RCT) is one of the most volatile and severe storm setups along the east coast, with a history of producing long-lived, destructive storms and supercells.
GFS Lifted Indices showing strong instability over the Darling Downs with LIs falling to -6 to -7. Source: Weatherwatch MetCentre.
One of the biggest contributing factors is an increase in low-level wind shear. Australian storms, while often severe, tend to be short-lived because they lack strong low-level inflow, which keeps the storm balanced and prevents it from becoming outflow dominated (thus cutting off the supply of warm, humid, unstable air). In RCT setups, strong low-level winds flow into storms, which not only aids in their longevity but also significantly increases the atmospheric turning, making conditions conducive to supercells. Supercells are nearly always severe and sometimes destructive.
ACCESS G Sounding: Note the strong turning in the low levels, this increases as the day goes on with 20-25 knot E/NE winds in the lower 1km of the atmosphere and 35-40 knot westerly winds 5-6km above the atmosphere providing 60-65 knots of bulk shear (40 knots is the threshold for supercells). Source: Weatherwatch MetCentre.
Because of this setup, there is potential for giant hail and destructive winds across areas of the Darling Downs, possibly extending into the Wide Bay & Burnett and the southern Central Highlands & Coalfields tomorrow.
For the Southeast Coast storms will be possible, particularly overnight as remnant activity from areas further west moves through which may bring some moderate falls over the region.
ACCESS C helicity tracks - indicates the likely potential for organised storms over the western Darling Downs. Source: Weatherwatch MetCentre.
Be Prepared
Today's setup appears to be a "standard" severe storm setup - and as always, caution should be taken on any day capable of producing severe storms.
Tomorrow however may be a high-end severe storm day - so if you live in the Wide Bay & Burnett, Darling Downs or southern Central Highlands & Coalfields we strongly advise you to heed all weather warnings consider what steps you need to take to prepare your home or business for potentially high-end severe storms.
Weatherwatch – your trusted partner in weather intelligence.