Effective as of 4:00 PM Saturday May 22 2021
Explanatory notes:
The cold front that is ahead of an upper level trough is currently moving across the region bringing rain and showers with isolated thunderstorms possible.
Cool moist air behind the front leads to some showers contracting to the coast/offshore overnight as a land breeze develops with increased stability over land. The slight chance of fog with radiational cooling of moist low level air with moist soils moistened by the rain.
Showers again from late morning tomorrow as the land breeze dissipates and a deep cold unstable air mass moves over the region. Thunderstorms and/or small hail possible with the depth of the instability being up to above the 400 hPa level.
Thunderstorm chances diminish overnight as the upper level cold pool moves away from the region lowering the depth of the instability but further showers in the cold southwesterly air stream and a cold day with the cold air mass over the region. Shower chances diminish by night with the formation of a land breeze with the ridge of high pressure building to the south.
A cold morning on Tuesday with the radiational cooling of the already cold air. Temperature below 5°C is likely in areas with cold air drainage and even below 3°C in the usually colder areas especially if skies are mostly clear.
Fine conditions and gradually becoming warmer until Thursday with the high pressure system moving into the Great Australian Bight.
A cold front ahead of an upper level trough likely arrived on Friday bringing showers with the possibility of thunderstorms with instability but still some uncertainty on the details this far out.
The rest of Saturday May 22:
Chance of any rain:100%
Perth Metropolitan Area:
Cloudy.A very high(100%) chance of rain and showers.The chance of a thunderstorm early this evening.Winds north-northeasterly at 10-20 km/h shifting south-southwesterly at 15-25 km/h in the evening.
Sunday May 23:
Showers.
Chance of any rain:100%
Amount:5 to 15 mm
Perth Metropolitan Area:
Partly to mostly cloudy. A very high (100%) chance of showers.The chance of a thunderstorm and/or small hail from afternoon.Light winds becoming southwesterly at 20-30 km/h from afternoon.