QLD, NSW: Rain on the way
Tue 29 Oct 2019
The planets seem to be aligning for some widespread half-decent rain across drought-stricken central and southwestern areas of QLD in the next couple of days, then western, central and southern parts of NSW over the weekend.
The rare and welcome visitor is an infeed of moisture from the Coral Sea and waters north of QLD into the state. It has combined with a trough through central QLD and a very slow-moving upper low over the state's southwest to produce a mix of showers, areas of patchy rain and thunderstorms.
Rain began this afternoon in an area of central QLD bounded roughly by Blackall, Charleville, Injune, Alpha, Longreach and Blackall with light rain also extending into parts of the South West. Totals to 23.00 AEST this evening have been variable, as that's the nature of the system, but higher reports include Blackall AP 17mm, Chesterton (90km NE of Augathella) 26, Fairview Alert gauge (SE of Alpha) 30 and Jericho 21. Almost all of the BoM automatic raingauges in the area reported between a few and 10mm with over a dozen in the teens. The rainy spell is expected to last into Thursday 31st, with the southwestern quarter of the state likely to average 25 to 50mm, though some places will do better and others worse.
The area of moist air will be slowly drawn south into NSW by Friday in the northerly airstream ahead of the next southern frontal system which will also provide the lifting mechanism to turn the moisture into precipitation. Once again, a mix of showers, patchy rain areas and thunderstorms can be expected across the west, south and central parts of the state ahead of the front on Saturday and Sunday with an average of 15 to 25mm looking likely. The North West Slopes and Plains and Northern Tablelands should also see a little of that rain on Monday, possibly an average of 10 to 15mm.
Rainfall is the hardest weather element to forecast because of its variability over short distances, so it's best to take all forward estimates as best-guess averages for your broad area. As with the QLD situation, rain in NSW will be patchy, and the presence of thunderstorms can give you nothing or a lot depending on whether you bag one or not.
In addition, the models each paint different scenarios for what they calculate will happen - sometimes slightly different, sometimes significantly so. Right now, three main models (US, European and Australian) are predicting 53, 7 and 20mm for my home near Orange through to Tuesday 5th. The reason the European model amount is so low, for example, is that it expects the front at the weekend to take a more southern track, reducing its influence over northern and central NSW. The moisture would still be there, but the mechanism to make it fall as rain would be reduced. Successive model runs with updated information will continue to fine-tune the expected scenarios and show up as variations in each new issue of the OCF forecasts.
It won't be a drought-breaker, but I hope it puts a smile on a lot of dusty faces.
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