Effective as of 12:00 PM Monday September 21 2020
Explanatory notes:Possible light maritime in moist southwesterly air flow on Monday.Mostly cloudy with the stratocumlus clouds trapped under the subsidence inversion.Also some high cloud.
A weak trough brings showers on Tuesday clearing by afternoon.
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, warm air mass over the region but some cloud cover, some elevated convection possible from Thursday afternoon with instability aloft ahead of the upper level trough.
The cut off low likely brings showers, possible thunderstorms from Friday, some uncertainty on the precise conditions.
Monday September 21:
City:
Max:18 Degrees Celsius
Possible light shower
Chance of any rain:30%
Amount:0 to 0.4 mm
Perth Metropolitan Area:
Mostly cloudy.A slight (30%) chance of light showers.Winds southwesterly at 15-25 km/h.
Tuesday September 22:
City:
10-21 Degrees Celsius
AM showers.
Chance of any rain:70%
Amount:0 to 2 mm
Perth Metropolitan Area:
Partly cloudy.A high (70%) chance of showers clearing by afternoon.Light winds tending south-southwesterly at 10-20 km/h in the afternoon.
Wednesday September 23:
City:
9-25 Degrees Celsius
Sunny.
Chance of any rain:0%
Amount:Nil
Perth Metropolitan Area:
Sunny.Winds easterly at 10-20 km/h tending northeasterly and light in the afternoon becoming southeasterly at 10-20 km/h from evening.
Thursday September 24:
City:
13-28 Degrees Celsius
Partly cloudy.
Chance of any rain:10%
Amount:Nil
Perth Metropolitan Area:
Partly cloudy.The chance of a thunderstorm from afternoon.Winds easterly at 20-35 km/h.
Friday September 25:
City:
13-24 Degrees Celsius
Showers.
Chance of any rain:70%
Amount:2 to 6 mm
Perth Metropolitan Area:
Partly to mostly cloudy.A high(70%) chance of showers.The chance of a thunderstorm.Winds northeasterly at 15-25 km/h shifting northwesterly later during the day.
Saturday September 26:
City:
13-22 Degrees Celsius
Showers.
Chance of any rain:80%
Amount:2 to 6 mm
Perth Metropolitan Area:
Partly to mostly cloudy.A high(80%) chance of showers.The chance of a thunderstorm.Winds west-northwesterly at 15-30 km/h.
Sunday September 27:
City:
13-21 Degrees Celsius
Showers.
Chance of any rain:60%
Amount:2 to 6 mm
Perth Metropolitan Area:
Partly to mostly cloudy.A medium(60%) chance of showers.The chance of a thunderstorm.Winds westerly at 15-25 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).
