Western Australia’s west coast is being hit by a prolonged period of gale force winds, rain and 10m waves as a major winter storm lingers south of the state for three days.
The system is so large that it is already sending a gust of strong winds and rain to the southeastern states, meaning it is currently affecting the weather over more than half of Australia.
As the week progresses the severest weather will move east and by Thursday heavy rain could cause flooding in parts of the Murray Basin.
The storm, a complex mid-latitude low pressure system, rapidly deepened off the southwest coast of Australia through Sunday and Monday, causing weather conditions to deteriorate rapidly across WA.
By midday on Tuesday, the storm had already dropped up to 50mm of rain on the outskirts of Perth and generated wind gusts of 137km/h at Cape Leeuwin.
This is well beyond the “damaging” threshold of 90 km/h and equivalent to the wind speeds recorded in a category 2 tropical cyclone.
Other notable wind and wave sightings include:
- Wave heights up to 9m at Cape Naturaliste and 8m at Rottnest Island
- Wind gusts at 117 km/h at Bickley and 115 km/h at Busselton Jetty
WA emergency services had already responded to more than 135 calls for help by sunrise Tuesday, a number expected to rise over the next 36 hours as the slow-moving low sends strong westerly winds with strong gales and huge waves on the coast of WA.
Throughout Tuesday and Wednesday, wind gusts will continue to peak well above 100 km/h, which will lead to the risk of damage to homes and property as well as power outages.
The prolonged duration of gales over a long stretch of ocean raises huge seas and swells to heights not typically seen on the west coast of WA in an average year.
A coastal erosion warning is in effect from Albany to Geraldton as waves rise to approximately 10m and maximum waves exceed 15m.
Stormy skies will start to ease across WA later on Wednesday as the low finally moves east into the Great Australian Bight, with southeastern states feeling the full force of the elements.
Warnings are already in place for much of South Australia and Victoria on Tuesday for gusty northerly winds on the eastern flank of the low.
Further alerts are likely through the middle of the week, although the gradual weakening of the system as it passes east should mean lower wind speeds and wave heights relative to WA.
The low is expected to continue to wane as it approaches Bass Strait but will then bind with tropical moisture to form a strong band of rain sweeping across Murray Basin Wednesday through Friday.
Farmers will see more than 20mm of rain over much of the NSW inland, including around 50mm on the mid-west and south-west slopes.
For New South Wales and the Victorian Alps, rainfall totals are expected to exceed 100mm, with most of it falling as rain due to the tropical air source.
Colder air from the Southern Ocean will gradually turn rain to snow on Friday.
The rain is expected to be heavy enough to trigger a flood watch for northeast Victoria and rivers flowing west of the Southern Ranges and the New South Wales Alps.
By Sunday, the remnants of the Monster Low will weaken further in the Tasman Sea.
On this occasion, the flood-ravaged NSW coast will be spared the worst of the storm’s wrath – but given the long-term forecast, the next round of heavy rain and flooding could be imminent.