September 21, 2024
The official start to the severe storm season (October 1) is just over a week away, and seasoned Southeast Queensland residents know what that means — watch out when there's storms in the forecast!
Missing Ingredient: Moisture
However, early in the season, there’s one crucial element currently missing — moisture, a key factor in creating unstable conditions that lead to thunderstorms. As of 6 am, dew points (a measure of moisture in the air) were well into the single digits across western areas of Southeast Queensland, creating an environment that's not primed for storm activity.
ACCESS-G Dew Point chart showing dry air pushing close to the coastline with moisture favouring coastal areas. Source: Weatherwatch MetCentre
Why Storms May Struggle to Form
In early storm season setups (not just in Southeast Queensland but across eastern Australia), storm potential can be hit or miss. There’s often plenty of cold air higher up in the atmosphere, which supports thunderstorms — and even severe storms — but the lack of moisture is a significant roadblock. Since thunderstorms are made up of billions of tiny water droplets, no moisture means no storms.
ACCESS-G 500mb temperatures showing a large mass of cool air across southeastern Australia - extending into Southeast Queensland. Source: Weatherwatch MetCentre
Today's Weather Setup
A weak southeast change will push up the coastline and inject some moisture and instability with today's setup sharing many similarities to the far more volatile "Modified Southeast Change" setup. But while the southeast change will bring some additional moisture (and instability), it will also bring a cooler airmass resulting in a strong cap developing which will likely inhibit storm development over much of the region.
ACCESS-C accumulated rainfall & surface winds showing precipitation is favoured around the Sunshine Coast region (and Wide Bay & Burnett). Source: Weatherwatch MetCentre
Storm Outlook: Very Marginal Risk
The highest chance of storms will likely lie around the Sunshine Coast where the cap may be slightly weaker - and if storms manage to maintain themselves, there is the chance of severe storms here. Elsewhere the risk of storms is highly marginal, but would occur close to the coastline if they do occur.
ACCESS-C sounding near the Sunshine Coast showing shallow but strong instability in the low to mid levels of the atmosphere. Supporting wind shear is present with good speed shear through the mid-levels, and turning in the lower levels but a strong cap will result in storms struggling to form and if they do occur, will be very isolated. Source: Weatherwatch MetCentre
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