October 19, 2024
October storm setups in Southeast Queensland are notoriously unpredictable. Being early in the season, moisture is often in short supply—especially when a stronger cold front pushes through, increasing the westerly flow.
Humid Northerlies vs. Dry Westerlies: A Fine Balance
The challenge today is that the hot, dry westerly winds are unlikely to reach the coastline. As a result, the coastal fringes of Southeast Queensland will stay humid, which could make conditions unstable enough for storm development. However, just 30-50km inland, the airmass will become much drier, reducing the potential for storms. At 11am, dew points on the Downs were already dropping, with gusty westerly winds driving the dew point down to 12°C in Oakey. But just a short distance eastward in Gatton, the dew point remains 19°C, showing a sharp contrast in moisture levels.
EC Dew Point& Surface Winds for Southeast Queensland. The westerly winds dry out much of the region by the afternoon resulting in more coastal potential. Source: MetCentre.
EC CAPE & Surface Winds for Southeast Queensland. Note how coastal the instability becomes late in the afternoon as the westerly winds squeeze in against the more humid, northerly winds. Source: MetCentre.
Comparison of soundings between Ipswich and the Sunshine Coast. This shows higher levels of moisture and instability closer to the coastline. Source: MetCentre.
A Complicated Setup: 700mb Moisture Plume
Adding further complexity is the presence of a moisture plume at the mid-level of the atmosphere (around 700mb). This may trigger mid-level or high-based showers and storm activity as the day progresses. The key unknown is whether this will be strong enough to break the cap near the coastline, allowing surface instability to be tapped into for storm development.
If storms do manage to break through, the highest risk appears to be in the area between Gympie and northern Brisbane, with Sunshine Coast being the most obvious area of concern. The moisture is expected to hold here longer, and the topography may help weaken the cap, increasing the storm potential.
EC Accumulated Rainfall for today (Saturday) showing a slight favouring of rainfall around the sunshine Coast. Source: MetCentre.
What to Expect
For most people today, storm activity will likely be weak, but there is still the chance of one or two isolated severe storms (especially between Gympie and Brisbane). These storms could bring damaging winds and large hail, so it’s worth keeping an eye on developments throughout the day.
Stay Updated
Given the unpredictability of today’s storm potential, we advise closely monitoring weather updates and warnings, particularly if you’re in the areas at higher risk as the weather can change rapidly in these setups. Even though storms may be isolated, the potential for severe weather remains.
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