DAY OF STRONG STORMS FOR WA

Overnight it has been noisy along the west coast with scattered showers and thunderstorms rolling through at regular intervals, bringing bursts of heavy rainfall and pockets of flash flooding to parts of the west coast. That will continue for Saturday and Sunday.


Rainfall observed in the 24hrs to 9am WST - Western Australia.

Top fall was 81mm north of Kalbarri. Scattered 20-50mm overnight with many at least seeing 10mm.

Satellite Imagery - WA.

Tracking areas of rain and thunderstorms over a wide area of the west coast on Saturday with heavy falls sweeping through at regular intervals from Exmouth down to the Margaret River. This activity will push inland today with further showers for the west coast on Sunday and potential heavy rainfall for the south coast of WA on Sunday night into Monday.

Thunderstorm Forecast - Saturday 29th May 2021.

90% chance (9/10) of thunderstorms developing within 25km of a given point during Saturday afternoon in the pink zones. The risk tapers down to 50% for yellow and 10% for white.

Thunderstorms will begin to contract further east over the coming 12-24hrs with isolated showers and thunderstorms to follow near the low along the west coast from later today.

Flash Flood Risk - Valid Saturday 29th May 2021.

Rating of flash flooding developing within 25km of a given point.

Low = 5-30% Moderate = 30-50% High= 50%-80%. Very High= 80-95%

The activity will then contract to the south coast during Sunday and into early next week with a low spinning up off the south coast with some moderate to heavy falls expected still. The weather will ease over the west coast as winds will be southerly keeping the showers parallel to the coast for now. Much colder few days coming up also, so when winds go calm expect there to be some local frost inland.


GFS 12z run 500mb/18000ft flow pattern - Valid Saturday 29th May 2021. Saturday.

Showing the upper low approaching the southwest with rain and thunderstorms moving through the region and extending inland by afternoon and evening with moderate to heavy falls possible from the Gascoyne through to Kalgoorlie and Norseman and points west. Warm and dry in the east with cloud increasing.

GFS 12z run Surface pressure and rainfall distribution - Valid Saturday 29th May 2021. Saturday

GFS 12z run 500mb/18000ft flow pattern - Valid Saturday 29th May 2021. Sunday

Rain and thunderstorms continuing over parts of the inland Saturday night through Sunday before contracting to the south coast during the day. A low developing offshore under the upper feature may enhance rainfall rates for the southern regions later in the day, between Margaret River and Albany. Severe weather warnings may be issued for heavy rainfall if the low sits close enough to the coast. Showers will ease over the west coast with partly cloudy skies as winds veer into the south.

GFS 12z run Surface pressure and rainfall distribution - Valid Saturday 29th May 2021. Sunday

GFS 12z run 500mb/18000ft flow pattern - Valid Saturday 29th May 2021. Monday

The upper low will be vertically stacked so a surface feature sitting underneath will continue to bring widespread showers and areas of heavy rainfall possibly to the south coast, with showers extending inland. Strong southerly winds continuing. Cloud will increase over the eastern border with SA with areas of rain developing later with strong northerly winds. Showers will be running parallel to the west coast with light falls expected if they do make landfall. Dry elsewhere.

GFS 12z run Surface pressure and rainfall distribution - Valid Saturday 29th May 2021. Monday

GFS 12z run 500mb/18000ft flow pattern - Valid Saturday 29th May 2021. Tuesday.

The low pressure system begins to weaken as it tracks into SA, taking the rain from the south coast to the east. Showers will decrease through the day as new ridging builds in from the southwest. More cloud developing over the Pilbara and Gascoyne coasts, but largely dry for now. Cold nights developing from this point over the southern and western inland as winds go calm and skies clear. Frost is a chance from mid next week in the morning.

GFS 12z run Surface pressure and rainfall distribution - Valid Saturday 29th May 2021. Tuesday.

Rainfall for the period will fall heaviest along the west coast from Friday through Sunday and along the south coast from Saturday to Tuesday. Further rainfall may develop over the Gascoyne regions come mid next week with another impulse of moisture along a trough.


Rainfall for the next 10 days - Valid Saturday 29th May 2021. Falls from Saturday Midnight.


Would you like more tailored weather information for your region? Email me at karllijnders@weathermatters.org for further details.

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