An East Coast Low (ECLs) are intense low-pressure systems which occur on average several times a year off the east coast of Australia, in particular southern Queensland, New South Wales and eastern Victoria, although they can occur at any time of year they are more common during autumn and winter with a max frequency of happening in June. ECLs will often intensify rapidly overnight making them one of the more dangerous weather systems to affect the NSW coast. ECL's are also seen off the coast of Africa and American and are sometimes known as east coast cyclones.
ECLs may form in a variety of situations, in summer they can be ex-tropical cyclones, at other times of year they will most often develop rapidly offshore with a pre-existing trough of low pressure due to favourable conditions in the upper atmosphere. ECLs may also develop in the wake of a cold front moving from Victoria into the Tasman Sea.
Gales and heavy rain occur on and near the coast south of the low centre, while to the north of the low can be clear skies, which can prove a challenge for forecasters is predicting the location and the movement of the centre of the low.
ECLs can generate one or more of the following:
> Gale or storm force winds along the coast and adjacent waters.
> Heavy widespread rainfall leading to the flash and/or major flooding.
> Very rough seas and prolonged heavy swells over coastal and ocean waters which can cause damage to the coast line.
Falling trees and flash flooding have caused fatalities on land and many small water craft have been lost off the coast and larger vessels have run aground during ECLs.