Effective as of 4:00 PM Saturday September 19 2020
Explanatory notes:Cold, unstable southwesterly air stream brings showers and also the possibility of small hail and thunderstorms with the cold pool extending aloft until the cold pool depth decreases.
Figure 3.Mean Sea Level Pressure(MSLP) analysis with infrared greyscale satellite image at 12 UTC(8 PM 
Lighter showers on Monday with a lowering of subsidence inversion heights.
A weak trough brings the possibility of showers on Tuesday.
Warm air advects over the region on Wednesday and likely also Thursday with the west coast trough deepening offshore. A cut off low forms ahead of an upper level trough from Thursday, all models but the GFS show the low forming to the northwest advecting hot air on Thursday.
The cut off low likely brings showers, possible thunderstorms from Friday, some uncertainty on the precise conditions.
The rest of Saturday September 19:
City:
Windy with showers.
Chance of any rain:100%
Perth Metropolitan Area:
Partly to mostly cloudy.A very high (100%) chance of showers.The chance of a thunderstorm and/or small hail.Winds southwesterly at 25-40 km/h. Gusty winds.
Sunday September 19:
City:
9-17 Degrees Celsius
Windy with showers.
Chance of any rain:95%
Amount:2 to 5 mm
Perth Metropolitan Area:
Partly to mostly cloudy.A very high (95%) chance of showers.The chance of small hail until afternoon.Winds southwesterly at 25-40 km/h.Gusty winds.
Monday September 20:
City:
9-18 Degrees Celsius
Possible shower or two.
Chance of any rain:40%
Amount:0 to 0.8 mm
Perth Metropolitan Area:
Partly to mostly cloudy.A medium (40%) chance of showers.Winds southwesterly at 15-25 km/h tending south-southeasterly and light in the morning.
Tuesday September 21:
City:
9-21 Degrees Celsius
Possible shower or two
Chance of any rain:40%
Amount:0 to 1 mm
Perth Metropolitan Area:
Partly cloudy.A medium (40%) chance of showers.Light winds tending south-southwesterly at 10-20 km/h in the afternoon.
Wednesday September 22:
City:
9-27 Degrees Celsius
Sunny.
Chance of any rain:0%
Amount:Nil
Perth Metropolitan Area:
Sunny.Winds easterly at 10-20 km/h.
Thursday September 23:
City:
13-29 Degrees Celsius
Partly cloudy.
Chance of any rain:10%
Amount:Nil
Perth Metropolitan Area:
Partly cloudy.Winds east-northeasterly at 20-30 km/h.
Friday September 24:
City:
13-24 Degrees Celsius
Showers.
Chance of any rain:70%
Amount:2 to 8 mm
Perth Metropolitan Area:
Partly to mostly cloudy.A high(70%) chance of showers.The chance of thunderstorms.Winds northeasterly at 20-30 km/h shifting northwesterly later during the day.
Saturday September 25:
City:
13-21 Degrees Celsius
Showers.
Chance of any rain:80%
Amount:2 to 8 mm
Perth Metropolitan Area:
Partly to mostly cloudy.A high(80%) chance of showers.The chance of thunderstorms.Winds northwesterly at 20-30 km/h.
Charts:
Figure 1.Surface synoptic chart at 12 UTC(8 PM local time yesterday).Image courtesy of the Australian Bureau of Meteorology(BOM).
Figure 2.Key features identified on True Colour RGB satellite image at around 06:00 UTC(2 PM local time yesterday).Satellite image courtesy of the Japanese Meteorological Agency(JMA).
local time yesterday).Image courtesy of the Australian Bureau of Meteorology(BOM).
Figure 4:Surface synoptic prognosis.Image courtesy of the Australian Bureau of Meteorology(BOM).
