CALMING DOWN OVER QLD AFTER A VERY HEAVY SPELL OF JULY RAINFALL

Bundaberg experiencing their wettest July weather since 2008, many centres inland of the coast through highlands and coalfields also experiencing their wettest July weather in more than 30 years in parts. All part of the positive SAM phase that is beginning to break down over the Southern Ocean.


The trough responsible is clearing out with a drier airmass moving in from the west, bringing a few days of seasonal conditions after cold starts with frost patches over large parts of inland Australia.


Rainfall for the coming 10 days - Valid Saturday 3rd of July 2021.

Rainfall has eased this afternoon over coastal areas of QLD with the trough nearly offshore the east coast. The rainfall dries out dramatically over inland areas from Sunday with a period of settled weather this week. The next system arrives through the southeast and eastern inland, potentially lifting moisture to produce a band of moderate rainfall before clearing south and east with a fast flow pattern developing over the south with a dry airmass returning for QLD in westerly winds into mid month.

The high bringing the settled weather is anticipated to move to the southeast of the region, causing winds to veer from the south into the east during mid week, so the humidity may increase again and showers return to coastal communities, but at this stage, without a trough in the region, the showers should be light and patchy for coastal areas.


The next wave of low pressure is expected to pass through SA during Thursday or Friday and this system is being forecast to run into moisture being drawn out of the northern parts of Australia, and lifted by this wave of low pressure, again sparking inland rainfall with possibly follow up moderate falls.


Euro 12z run - Surface Pressure Pattern and Rainfall Distribution - Valid Saturday 3rd of July 2021.

The pattern is looking very winter like as we go through the week, losing that deep moisture layer from anomalous easterly winds of this week. Another trough may bring more rainfall later this week into the weekend, then a westerly wind belt will surge north over southern Australia, planting the eastern inland of QLD under a stable upper high with seasonal conditions and a dry airmass for the most part there after that rain potential.

GFS 18z run - Surface Pressure Pattern and Rainfall Distribution - Valid Saturday 3rd of July 2021.

The model handles this week's drying out in line with the Euro and indeed other modelling agencies. It is from later in the period that the diverging in the models occurs with the placement of the rainfall event through the east with mixed odds for rainfall through QLD and NSW. So this will become clearer from tomorrow night if not Monday. Then good agreement again with the weather becoming more winter like with the mainly westerly wave action engulfing southern Australia with multiple waves bringing wet and cold weather to our south, we stay mostly dry. Though the last system in this run from this morning, shows rainfall coming back for eastern inland areas.


With the lead system being around 6 days out, AGAIN the distribution, scale, intensity and timing of the system will continue to chop and change as the data is based of computer prognostics and not real time analysis and so forecast accuracy will improve once we can see the systems unfolding in real time.


Rainfall for the next 10 days - GFS Valid 18z Saturday 3rd of July 2021.

Rain clears offshore the east overnight then light to moderate rainfall back on the cards later in the week over central and southern QLD, but this will and likely change over the coming days. Then after that potential rainfall I do think we tend drier into mid month with westerly winds developing dragging in dry continental air under a weak upper ridge.

Rainfall for the next 10 days - Euro Valid 12z Saturday 3rd of July 2021.

Rainfall clears eastwards from QLD now and then a dry spell this week. Note the rainfall spread is more widespread as opposed to GFS with the trough further north over the eastern inland meaning more rainfall would be on offer for QLD in this scenario. Like GFS, good agreement where the models suggest a westerly wind profile keeping much of QLD dry after that event later this week.


This lead system coming in following the high, will beat down the ridge, flattening the upper ridge and park it over the eastern and central interior, adopting a winter time position, meaning seasonal and dry windy weather to follow while the south endures front after front with wintry wet weather.


However, one or two of these fronts may interact with moisture from the Indian Ocean and could bring bands of light rainfall through northern parts of NSW and into southern QLD. So will watch for that possibility in the medium term.


GFS 00z run - Precipitable Water Values Anomalies - Valid Saturday 3rd of July 2021.

The very latest data set on the PW Anomalies through the coming 2 weeks shows that decent chunk of moisture surging in from northern parts of Australia, lifted by a trough and front then moving out. Note the fast flow pattern for about a week after keeping the QLD region dry in a westerly, but then in the medium term a low pressure system comes in a zone that would favour the rainfall entering the central and eastern interior moving through mid to late month, but that is so far out in the distance it will be likely gone next run, but I mention this as an example of what the late winter and spring will look like and where the moisture source will come from during the second half of the year, not just from easterly winds. So a heads up on that.


The weather pattern is what one would expect at this time of year with the zonal winter westerly pattern underway in the middle of winter. That is to seasonal expectations.


So the takeaway is, after all this rainfall in recent days, another wave of rain is possible in about one week and then a dry and seasonal period to follow.

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