RAINFALL BECOMING MORE WIDESPREAD ON TUESDAY BEFORE SPREADING THROUGHOUT TONIGHT

The cloud band has been wafting offshore for a number of days now, sending a high cloud shield over the SWLD, keeping temperatures down and not letting a lot of sunlight through. Patchy rainfall has begin to fall on Monday and it did persist overnight with light falls for some locations up through the Gascoyne and into the southern interior.


Rainfall has increased offshore along a strengthening cold front and low pressure system, that is expected to sweep through the southwest land division bringing moderate to heavy falls across areas from about Lancelin through York down through to about Esperance. 20-30mm in this region is fair. But the band could shift north and south as it approaches and this will impact rainfall.


The low moves east as cold fronts move in from the west. These will help to push the low east and clear the rainfall off but showers will increase once again for the west coast thanks to fast moving cold fronts pushing through the region. The cold fronts won't be bringing severe weather at this time but they could produce widespread rainfall.


Coming into the weekend, more frontal weather is expected to push through with further showers and even looking at the modelling this morning more rainfall is expected to develop with further cold fronts over the south and west of the state.


Moisture may come back through the inland with a front to possibly link up with that moisture producing more widespread cloud and inland rainfall. But the risk at this time is considered low.


12Z GFS Surface Pressure Pattern for the coming 16 days

The pattern is largely unchanged from overnight which is good for forecasters, rain did break out along the lead trough over the northern parts of the SWLD and the southern Gascoyne which has verified, dry weather over the southern areas will change with rainfall increasing this morning and becoming heavy at times later today and extending inland as the low moves through. A gusty northeast to northerly wind will back southwesterly but it shouldn't be cold, more seasonal for this time of year. The rainfall then moves east of the region with the low handed off to SA into Thursday, but frontal weather will pass through the state's southwest during Thursday evening and more likely Friday with a stronger system over the weekend bringing gusty winds, widespread showers and moderate falls to the same areas that have copped a belting this July. More fronts continue next week as the westerly wind regime remains in force.

12z GFS Rainfall for the coming 10 days

Rainfall increasing this morning as we have already seen and is ongoing for inland areas. Rain develops elsewhere from later this morning and continues through to Wednesday morning and then clears the east later tomorrow. Showers to follow over the west and southwest coasts with gusty onshore winds. These could bring small hail and thunder too. Next week more rainfall is expected for the west coast, but inland rainfall may also develop thanks to another surge of moisture which we spoke of yesterday. I will be looking at that a little later today.

12z Euro Surface Pressure Pattern for the coming 10 days

The Euro is in good agreement this morning for the system passing through over the coming 24hrs. So this clearly will be the most widespread rainfall event this week. Showers to follow later this week in a westerly wind regime. Some moderate falls are likely to continue into the weekend with an unstable westerly wind regime. The inland may return to mostly dry with a few passing showers from time to time, but I do think the bulk of the rainfall will be coastal following this event. Next week that may change, with inland moisture supply increasing. So I think there will be some rainfall returning to inland parts of WA next week.

12z Euro Rainfall for the coming 10 days

Rainfall is falling and will continue to increase in line with the approach and passage of the trough and low today, then easing from later Wednesday from west to east. The rainfall contracts back to the coast and as you can see good agreement in the modelling keeping the chance of rainfall daily for the west coast and southwest coast too, daily. So there is not one completely dry day expected without the chance of rainfall through the outlook for the coastal areas south of Lancelin to about Esperance, but inland areas will see more breaks in the rainfall.

Rainfall for the coming 10 days.

Rainfall largely unchanged from overnight though I have lifted totals to the south of Perth with the follow up frontal weather and increased falls a little through inland areas with the rainfall coming through today. More rainfall may develop next week further north and east of Meekatharra to Warburton with another moisture surge and frontal weather will continue next week for the SWLD while the moisture continues to build over the Indian Ocean.

More weather to come throughout the day plus my Climate Outlook for August from lunchtime today.





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