Summary
Highlights
A significant all-hazards severe weather and thunderstorm threat is expected across southwestern and Western Australia on May 30th, 2026. This includes potential for severe thunderstorms later today and powerful winds from a cold front sweeping through tomorrow, leading to a prolific severe weather outbreak.
Satellite imagery shows a trough developing ahead of a main low-pressure system (1000 hPa). A secondary low-pressure area is forming offshore, connecting with the main frontal system. Tropical moisture from the Indian Ocean is being drawn down, bringing heavy rainfall to the central west coastline, expected to reach Perth later this afternoon and evening.
A very intense trough with surface-based winds from the northeast and upper-level winds from the northwest will create wind shear, leading to a severe thunderstorm risk across a corridor from south of Geraldton to Perth. This is expected late afternoon into evening, arriving in Perth between 6-8 PM. There's an isolated risk of brief, weak, messy tornadoes, particularly in the northern peripheries of Perth and up to Geraldton, due to rotating thunderstorms.
The low-pressure system is undergoing baroclinic forcing, dropping 20 millibars in 16 hours, satisfying the definition of a bomb cyclone. It's expected to bomb out to 978 hPa offshore from Augusta, indicating a very intense system. Damaging wind gusts will develop around Perth tonight, but the main severe winds will arrive tomorrow evening, with gusts exceeding 125 km/h for coastal locations, causing significant wind-related damage.
Conditions will quickly ease for Perth by tomorrow morning, though remaining blustery. The severe weather threat will contract eastwards towards Esperance. Significant rainfall is expected, with 30-60 mm between Kalbarri and Geraldton, 20 mm in Perth, and up to 50 mm in southwestern capes, reaching 70 mm in the hills. Flash flooding is not a major concern due to the fast-moving nature of the showers.
The system brings significant instability with CAPE values up to 700-800, contributing to the severe thunderstorm threat. Instability will extend to Perth tomorrow night, bringing destructive wind gusts and a continued risk of cold core tornadoes. Subsequent frontal systems will brush southwestern WA late Tuesday, but they are not expected to be as severe, marking the start of a showery and wet winter.
This is a very significant wind-related severe weather event for southwestern WA, impacting areas from Kalbarri to Augusta, including Perth and the Wheatbelt. Residents are advised to prepare for damaging and destructive winds tonight and tomorrow, heeding all warnings and staying informed.
The eastern states (New South Wales, southern Queensland, South Australia, Victoria, ACT, Tasmania) are experiencing calm, collected, and generally unpleasant, cool conditions due to a low-pressure system in the Tasman Sea. While a deep low-pressure system (986 hPa) will move into the Bight next week, it's not expected to bring severe weather, but rather widespread blustery, showery, and cold conditions with significant rainfall in some areas, especially Victoria.
Other parts of Australia, specifically the north, will experience fine, calm, and collected weather, with increasing fire dangers. The forecast concludes with a reminder for residents in southwestern WA to stay safe and prepared for the significant weather event, with the possibility of a follow-up update later today.