September 27, 2024
Low Brings Damaging Winds and Rainfall
A low has developed off the northern NSW coastline today, bringing damaging wind gusts of up to 117km/h at Byron Bay. Widespread rainfall of 60-80mm has already been recorded across parts of the NSW Northern Rivers and Mid North Coast, with another 24 hours of rain still to come. Further damaging wind gusts are likely, particularly over northeast NSW, and could extend into parts of Southeast Queensland tomorrow, with conditions similar to an "East Coast Low." However, this system is not expected to be classified as one.
C3 950mb wind loop showing the low approaching the coastline tomorrow. Source: Weatherwatch MetCentre
A Rare September Low: Unusually Warm Oceans and Upper Trough
Heavy rain and gales in the cooler months are often caused by East Coast Lows, but this event doesn’t fully fit that definition. Ocean temperatures off northern NSW and southern Queensland are about 1 to 1.5°C warmer than average, which doesn’t sound like much but provides significantly more energy to the system. As the upper trough approached, it caused the warm, humid air from the ocean to rise rapidly, leading to the formation of this low-pressure system.
Warm ocean temperatures are contributing to the development of the low. Source: Bureau of Meteorology.
Main Threats: Damaging Winds and Dangerous Surf
The most significant impact from this system is likely to be damaging winds, especially along the northeast NSW coastline and around the NSW/QLD Border Ranges, possibly extending into the Gold Coast region. Winds could strengthen tomorrow morning, continuing throughout the day before easing late in the evening. Damaging wind gusts are unlikely more than 5-10km inland (except in exposed or elevated areas), but gale-force gusts could still bring down large branches or trees.
C3 950mb winds at 2pm, Saturday September 28, 2024. Note that these winds won't necessarily reach the surface, but provides an indication of maximum wind potential over coastal or elevated terrain. Source: Weatherwatch MetCentre
Heavy Rainfall and Potential Flooding in NE NSW
With 60-80mm of rain already recorded, a further 100-150mm is expected, which may cause minor flooding in the region. Flood watches are currently in place. For residents concerned about a repeat of 2022, it’s important to note that this system is quite different. The 2022 event lasted for days, whereas this system’s most intense period should be limited to 36-48 hours, some of which has already passed.
EC, GFS & G3 Forecast Rainfall for the next 72 hours. Source: Weatherwatch MetCentre
Conditions to Ease by Sunday
Thankfully, the low is expected to weaken and move away by Sunday, resulting in both winds and rain rapidly easing. A more stable and settled week is anticipated once the system clears. Our forecasting team will continue monitoring the situation closely and provide 24/7 updates to our clients until the threat has passed.
G3 wind barbs & cloud cover on Sunday showing easing winds and clearing skies favoured by Sunday. Source: Weatherwatch MetCentre
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