LATEST DETAILS ON RAINFALL FOR WA THIS WEEKEND.

A dry few days are underway over the western parts of the nation as a high pressure ridge builds in rapidly, following the cold front which brought cold and blustery showery weather yesterday.


A quick wrap of rainfall shows that most southern and western coastal areas received 10-30mm of rainfall with some places clocking up 40-50mm. Inland areas did not fair as well which was expected with the orientation of the weather systems, light falls of 2-10mm achieved with the higher falls the further south and west you went through the SWLD.


With high pressure ridging in, settled for the coming days with temperatures moving above average over the course of the coming days as the east deals with cold and showery weather.


GFS 12z Temperature Anomalies Saturday - Valid Wednesday 30th of June 2021.

GFS 12z Temperature Anomalies Sunday - Valid Wednesday 30th of June 2021.

But as you can see offshore the west coast on Sunday, there is a mass of blue, indicating that indeed another set of fronts is on the way.


Euro 12z run - Surface pressure pattern and rainfall distribution - Valid Wednesday 30th of June.

Note the high moving over the east following a weak cold front that may bring a few coastal showers to southern areas on Thursday afternoon. From there we are dry out west with settled conditions for much of Friday and Saturday. It Sunday, a large cold front and low pressure system offshore brings the next chance of rainfall and wintry weather to the region.

GFS 18z Precipitable Water Values next 2 weeks - Valid Wednesday 30th of June 2021.

The PW values ahead of the front increase dramatically with a northwest flow aloft dragging in the moisture from the Indian Ocean, this providing support for a rain band to sweep through. Multiple cold fronts that follow this first system also have the potential to each bring a band of rain and storms to the west and southwest coasts as they pass through with gusty winds. The fast flow pattern thanks to the SAM returning to neutral values next week and possibly going negative which supports more frontal activity.

Euro 12z run - Simulated Water Vapour Satellite - Valid Tuesday 29th of June.

I shared this yesterday showing the movement of moisture through the atmosphere and whether there would be any connection with the moisture and the fast flow pattern with cold fronts racing north. There is plenty to work with out there and it is a matter of not IF but WHEN in this case given the climatic drivers. More can be found here

So putting that all together, the rainfall spread has not changed too much for the southwest and west of the nation. I am not going to draw a chart just yet for northern WA as there is no consistency on model guide for rainfall there just yet, but I do believe there will be something to work with come Friday once the east coast situation resolves. Models struggle to place weather systems when there is a lot on the board at one time, hence you see the rainfall jump all over the place. For that reason I keep the rainfall charts settled and conservative.


Rainfall for the next 10 days - Valid Wednesday June 30th 2021.

I have left it unchanged with the latest data sets coming through this morning, though I will update this again later on this afternoon. Rainfall heavy at times along the southwest coast with a persistent southwest to westerly wind regime bringing in multiple fronts over the course of 10 days from Sunday. Some of that may link into moisture streaming in from the Indian Ocean and so while there is little on the board for interior regions, this is expected to change in coming days.

Need more weather information? Email me at karllijnders@weathermatters.org for further details on how I may be able to help you get the information you need to make informed decisions.

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