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).
Forecast updated to reflect latest trends.Boundary layer decoupling leading to colder than expected conditions.Temperatures will rise back slightly with boundary layer recouping as winds strengthen but there is the chance that will not happen till sunrise.
Sunday morning was the coldest since October with minimum temperatures of 10.5 Degrees Celsius at the Perth Metro station,even colder at Jandakot at 5.7 Degrees Celsius with some cold air drainage.The low temperatures were due to already cool and dry air encountering radiational cooling overnight.
Some high clouds may affect the region today streaming in a subtropical jet stream.
On Tuesday especially plenty of high clouds with moist air streaming in a subtropical jet stream and later some middle level clouds as well ahead of a middle level disturbance,virga possible but unlikely to reach the ground with a thick layer of dry air below the clouds.
A west coast trough formed near the west coast today leading to warm air advection.Some uncertainty on how hot it will be mid week with variation between models and ensemble members but it could be very hot.
Plenty of uncertainty on the precise synoptic conditions late during the week as it depends on the movement of Tropical Cyclone Marcus but an easterly pressure gradient is likely.
Monday March 19:
City:
13-32 Degrees Celsius
High clouds(mostly sunny).
Chance of any rain:0%
Amount:0 mm.
Perth metropolitan area:
High clouds(mostly sunny).Winds east to southeasterly at 10-25 km/h tending south-southwesterly at 10-25 km/h in the afternoon and evening over western suburbs.
Tuesday March 20:
Perth metropolitan area:
Tuesday March 20:
City:
20-34 Degrees Celsius
Clouds increasing.
Chance of any rain:5%
Amount:0 mm.
Perth metropolitan area:
Mostly sunny becoming mostly cloudy from late afternoon,high clouds.Winds easterly at 20-35 km/h easing to east-northeasterly 10-20 km/h during the afternoon increasing to easterly at 20-30 km/h later at night.
Wednesday March 21:
Perth metropolitan area:
Wednesday March 21:
City:
24-36 Degrees Celsius
Partly cloudy.
Chance of any rain:10%
Amount:0 mm.
Perth metropolitan area:
Partly cloudy.Winds east-northeasterly at 15-30 km/h easing to 10-20 km/h in the afternoon from afternoon increasing to 20-30 km/h by late at night.
Thursday March 22:
Perth metropolitan area:
Thursday March 22:
City:
21-29 Degrees Celsius
Mostly sunny.
Chance of any rain:0%
Amount:0 mm.
Perth metropolitan area:
Mostly sunny.Winds northeasterly at 10-20 km/h becoming southwesterly at 15-25 km/h during the day becoming south-southwesterly at 10-20 km/h at night.
Friday March 23:
Perth metropolitan area:
Friday March 23:
City:
17-28 Degrees Celsius
Partly cloudy.
Chance of any rain:10%
Amount:0 mm.
Perth metropolitan area:
Partly cloudy.Winds south-southwesterly at 15-25 km/h.
Saturday March 24:
Perth metropolitan area:
Saturday March 24:
City:
17-28 Degrees Celsius
Partly cloudy.
Chance of any rain:5%
Amount:0 mm.
Perth metropolitan area:
Partly cloudy,high clouds.Winds southeasterly at 15-25 km/h.
Sunday March 25:
Perth metropolitan area:
Sunday March 25:
City:
17-28 Degrees Celsius
Partly cloudy.
Chance of any rain:10%
Amount:0 mm.
Perth metropolitan area:
Partly cloudy.Winds easterly at 15-30 km/h.
Forecast for today produced at 3:00 AM,forecast for the rest of the days produced at 4:20 PM Sunday March 18.Weather icons courtesy of the US National Weather Service.
