MetraWeather is alerting industry to a significant winter frontal system due to impact Western Australia early next week, bringing areas of heavy rain, thunderstorms and damaging wind gusts to many districts.
Whilst this type of weather is not considered unusual for the South West Land Division during the winter months, it is less common for areas further north.
MetraWeather Business Development Manager Alex Zadnik says there is good agreement in the numerical weather prediction modelling that a strong cold front will approach southern districts on Monday 4 June.
“Ahead of this, a pre-frontal low pressure trough will deepen and draw on moisture-laden air sitting over the tropical Indian Ocean.
“This will be the source of unseasonal heavy rains for areas between Carnarvon and Onslow (including Barrow Island), particularly during Tuesday and Wednesday. Forty-eight-hour rainfall totals above 50mm will be widespread, while localised falls in the 100-200mm range are likely,” he says.
Rainfall totals of this magnitude are rare in winter for the Pilbara. The average monthly rainfall for Learmonth and Onslow in June is below 50mm. For Learmonth the record 24-hour total in June is 95mm, which could be challenged. Heavy rain should also spread from Onslow to Dampier during Tuesday and Wednesday.
“The approach of this dynamic weather pattern will also bring the risk of damaging wind gusts above 90km/h to coastal areas of the Gascoyne and neighbouring parts of the Pilbara district, especially on Monday evening and Tuesday.
“There is also the risk of thunderstorm activity during this period, meaning an elevated threat of lightning, in addition to the other safety hazards brought by the unseasonal heavy rain and winds."
MetraWeather is a subsidiary of the MetService of New Zealand (MetService), New Zealand’s national weather authority and official provider of public weather safety services.
Business Development Manager