Explanatory notes:
Scroll down below this section for forecast.
Figure 3.Mean Sea Level Pressure(MSLP) analysis with infrared greyscale satellite image at 12 UTC(8 PM local time yesterday).Image courtesy of the Australian Bureau of Meteorology(BOM).
Showers and thunderstorms have been affecting the far southwest of the area today associated with a pre frontal trough in an unstable atmosphere.
Some thunderstorms to the northwest ahead of an upper/middle level trough will affect the region in the next few hours.
The strongest cold front since spring last year moves over the region on Sunday morning associated with a complex low to the south bringing showers and thunderstorms.Thunderstorms likely with 800 J/kg CAPE with possible heavy rainfall plenty of low level moisture as indicated by dew points up to 18 Degrees Celsius expected.Can't rule out hail with relatively cold air aloft.
It is rare for a cold frontal passage over the region to be accompanied by such high CAPE.
Thunderstorms and heavy rainfall most likely between 8 AM to 11 AM as a line of low level wind convergence between northwesterly winds and the north-northeasterly land breeze moves through as predicted by the ECMWF model.
Post cold frontal showers affect the region thereafter with improving conditions from Tuesday as a ridge of high pressure builds to the south.
The rest of Saturday April 21:
City:
Shower or thunderstorm or two.
Chance of any rain:60%
Perth metropolitan area:
Partly to mostly cloudy.A medium(60%) chance of showers and thunderstorms.Light winds except with showers and thunderstorms where gusty winds possible.
Perth metropolitan area:
Sunday April 22:
City:
16-23 Degrees Celsius
Showers and thunderstorms.
Chance of any rain:100%
Amount:8 to 25 mm.
Perth metropolitan area:
Partly to mostly cloudy.A very high(100%) chance of showers and thunderstorms.Heavy falls and gusty winds possible especially with thunderstorms.Possible hail.Winds north-northeasterly at 10-20 km/h becoming northwesterly at 20-35 km/h from mid morning becoming west-northwesterly from afternoon easing to 20-30 km/h at night.
Perth metropolitan area:
Monday April 23:
City:
16-22 Degrees Celsius
Shower or two.
Chance of any rain:50%
Amount:0 to 1 mm.
Perth metropolitan area:
Partly cloudy.A medium(50%) chance of showers.Winds west-southwesterly at 15-25 km/h becoming southwesterly from afternoon becoming light at night.
Perth metropolitan area:
Tuesday April 24:
City:
12-22 Degrees Celsius
Partly cloudy.
Chance of any rain:10%
Amount:0 mm.
Perth metropolitan area:
Partly cloudy.Light winds becoming south-southwesterly at 10-25 km/h from afternoon becoming south-southeasterly at 10-20 km/h at night.
Perth metropolitan area:
Wednesday April 25:
City:
11-24 Degrees Celsius
Sunny.
Chance of any rain:0%
Amount:0 mm.
Perth metropolitan area:
Sunny.Winds east-southeasterly at 10-20 km/h tending south-southwesterly at 10-25 km/h in the afternoon and evening.
Perth metropolitan area:
Thursday April 26:
City:
14-28 Degrees Celsius
Sunny.
Chance of any rain:0%
Amount:0 mm.
Perth metropolitan area:
Sunny.Winds easterly at 10-20 km/h becoming light from afternoon.
Perth metropolitan area:
Friday April 27:
City:
16-27 Degrees Celsius
Partly cloudy.
Chance of any rain:0%
Amount:0 mm.
Perth metropolitan area:
Partly cloudy.Winds east-northeasterly at 10-20 km/h becoming light from afternoon.
Perth metropolitan area:
Saturday April 28:
City:
15-25 Degrees Celsius
Partly cloudy.
Chance of any rain:5%
Amount:0 mm.
Perth metropolitan area:
Partly cloudy.Light winds.
Forecast for today produced at 1:00 AM forecast for the rest of the days produced at 6:00 PM Friday April 20.Weather icons courtesy of the US National Weather Service.
