Learn about east coast lows, how they form, why they are dangerous and how they're different to cyclones.
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East coast lows are one of Australia's climate influences. Some of our worst maritime disasters are caused by the destructive winds, torrential rainfall and rough seas that come with stronger east coast lows.
These intense low pressure systems happen, on average, several times each year off the continent's eastern coast. Particularly, in southern Queensland, New South Wales and eastern Victoria.
They can occur at any time of year but are more common during autumn and winter, most frequently in June.
East coast lows often intensify quickly over 12-24 hours. This makes them one of the more dangerous weather systems to affect the eastern coast.They also happen off the coast of Africa and America and are sometimes called east coast cyclones.
East coast lows can form in a range of weather situations.
In summer, they can develop from ex-tropical cyclones as these decay and move south.
At other times of the year, east coast lows often develop rapidly just offshore. This can happen within an existing trough of low pressure, due to favourable conditions in the upper atmosphere combined with warm sea surface temperatures.
East coast lows may also develop in the wake of a cold front moving across from Victoria into the Tasman Sea. The warm sea surface temperatures associated with the East Australian Current are also an important factor contributing to the development of the systems. The sea surface temperature gradients associated with the warm eddies of the East Australian Current help the lows develop.Gales and heavy rains can often occur on and near the coast south of the low centre, while there can be clear skies to the north of the low. The challenge for forecasters is to accurately predict the location, movement and intensity of the centre of the low.
Each year there are about 10 east coast lows that have significant impact. We generally only see 'explosive' development about once a year.Looking at all the lows detailed in our database since 1973, there is no evidence of a trend.
East coast lows can create one or more of:
During past east coast lows:
Pasha Bulker was grounded on a reef just off Nobby's Beach near Newcastle, NSW, by an east coast low in June 2007. Credit: Brett Delaney, ex-Bureau weather observer.
Tropical cyclones develop over very warm tropical waters where the sea surface temperature is greater than 26° C. This gives them a unique structure and behaviour, very different from an east coast low. They have relatively long life cycles - typically about a week.
Severe tropical cyclones can produce:
East coast lows can produce:
While maximum wind speeds recorded are lower than in severe tropical cyclones, significant gusts have been recorded at Newcastle:
View the National warnings summary.