Western Australia Braces for Extreme Weather: Heatwave, Cyclone Mitchell’s Remnants, and Tropical Cyclone Narelle on the Horizon
A series of powerful weather systems are converging on Western Australia, delivering a dramatic mix of conditions ranging from a brief cool change in Perth to severe heatwave warnings statewide, and the menacing approach of Tropical Cyclone Narelle.
Heatwave and Brief Cool Change in Perth
Elevated temperatures are forecast to persist across much of Western Australia throughout the week. Severe heatwave conditions are predicted for segments of the southern, central, and northern parts of the state, with some areas potentially experiencing extreme heatwave conditions. Temperatures in the northern regions are forecast to moderate slightly by the end of the week.
A brief shift to cooler temperatures is anticipated in Perth later in the week due to a weak weather system moving through southern Western Australia. In the Perth CBD, conditions are forecast to be sunny, stable, and warm through the midweek, with maximum temperatures around 30 to 31 degrees Celsius.
A new ridge is expected to establish, introducing a south-westerly airflow over Perth. The cooler air is forecast to be most noticeable during the early parts of the day, with afternoons warming rapidly under predominantly clear skies. No significant rainfall is predicted for the metropolitan area during this period.
Ex-Tropical Cyclone Mitchell
Ex-Tropical Cyclone Mitchell crossed the Western Australian coast early Tuesday, bringing rainfall to some regions. The Bureau of Meteorology downgraded Mitchell to an ex-tropical cyclone overnight before it made landfall on the Gascoyne coast east of Shark Bay.
Significant rainfall totals were recorded, including 132mm at Gascoyne Junction and 104.2mm at Shark Bay Airport. A severe weather warning was in effect for the central Wheatbelt and parts of the Gascoyne and Central West regions, forecasting heavy rainfall that may cause flash flooding. A cyclone advice warning for Shark Bay and Denham, including Monkey Mia, remained in place, though the threat level decreased. A minor flood warning was issued for the Fitzroy River at Fitzroy Crossing.
Perth recorded 2.2mm of rain due to its location on the periphery of Mitchell's cloud band. Showers were forecast to clear gradually, with the metropolitan area expected to dry out with sunny weather from Wednesday.
Tropical Cyclone Narelle
Tropical Cyclone Narelle is tracking towards Western Australia and is forecast to influence weather conditions across the state. The system crossed the northern parts of the Kimberley and is expected to move into open waters west of the region.
Trajectory and Intensification
The Bureau of Meteorology (BOM) indicates Narelle could reintensify to tropical cyclone strength over open water. There is a possibility it could reach severe tropical cyclone strength. The system is expected to run parallel to the Pilbara coast before heading south.
Various models present a range of scenarios, including a more southward track towards the WA coast. BOM states there is a possibility of a direct impact on Perth, though models show a wide spread of outcomes. Bureau meteorologist Helen Reid stated it is too early to precisely predict the tropical system's path.
Current Status and Warnings
The system has been reclassified as a tropical cyclone. Narelle has intensified into a Category 3 system, bringing destructive conditions to coastal regions. Near the Pilbara coastline, the system generated sustained winds of 150 km/h and gusts up to 200 km/h.
Active tropical cyclone warnings are in place from Pardoo Roadhouse to Cape Cuvier, encompassing Port Hedland, Karratha, Onslow, Exmouth, Coral Bay, and inland to Pannawonica. Port Hedland International Airport canceled all Virgin and Qantas flights for Thursday due to the system.
Damaging wind warnings, up to 90 km/h, were issued for residents along the Darling Scarp, including Armadale, Ellenbrook, Kalamunda, Gingin, Dwellingup, and Harvey. Officials explained that a high-pressure system southwest of the state, combined with a trough off the west coast, will generate a vigorous easterly airstream. Winds are anticipated to reach speeds between 55 and 65 km/hr, with peak gusts of 90 km/hr predicted for the Perth Hills.
Main roads in and out of Exmouth were scheduled to close. An evacuation center was established at the Exmouth Shire Hall.
Perth Impact and Flood Warnings
Perth is under alert, with residents advised to expect severe weather conditions. Heavy rainfall is forecast for Perth on Friday and Saturday. BOM meteorologist Helen Reid indicated that flash flooding remains a possibility for some parts of the metropolitan region.
A flood watch warning has been issued for the Kimberley region. A flood watch warning was also issued for catchments like the Swan River, which may experience level rises and overflow flooding. A minor flood warning was issued for the Fitzroy River.
Historical Context
If Narelle crosses the metropolitan area, it would mark the first cyclone to hit Perth in 36 years, following significant rainfall from Cyclone Seroja in 2021. Reid urged Perth residents to regularly monitor weather websites for updates, emphasizing that conditions can change rapidly.