Windy Sunday for southwest WA

Drew Casper-Richardson, 11 March 2018

Easterly winds gusting up to 100km/h will tear through southwestern parts of Western Australia on Sunday morning.

A Severe Weather Warning for damaging winds was issued for the Lower West and northern parts of the South West as gusty easterly winds buffeted the region.

A strong high pressure system to the south combined with a low pressure system to the north allowed this strong easterly flow to develop along much of southern half of the west coast. These winds are particularly strong about the Lower West and northern parts of the South West due to a phenomenon called 'downslope winds'.

Downslope winds occur when conditions in the upper atmosphere create a "cap" which keeps the energy closer to the surface of the earth, with no way of escaping. When these winds encounter hills or mountains they are "squeezed", focusing the energy and increasing the wind speed as air rushes down the hill.

In southwest WA, these easterly winds are hitting the Darling Escarpment and racing down the western slopes. Wind gusts could potentially reach 100km/h, most likely on the hills themselves or in the foothills. However, it cannot be ruled out throughout the warning area, including Perth.

Winds are expected to ease below damaging strength by around 8am AWST on Sunday, however winds will be gusty throughout the day.

- Weatherzone

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