Townsville’s 2017 rainfall: no relief from dry conditions

As most of us have been expecting for a while now, Townsville’s 2017 rainfall total was on the low side. The BOM’s raw figures show that we had 791 mm for the year, well below our nominal average of 1135 mm.

I say “nominal” average because, as I said here almost two years ago, an average year is not normal: we get dry years (and 2017 is one of them) or wet years (e.g. 2007 – 2012) but rarely get a total resembling the average. Our 2016 total was 951 mm, which is close to average but still on the low side; adding these two years on to the end of the list of rainfall totals shows that we haven’t yet broken out of the succession of dry years which began in 2013.

What this has meant for our water supply is an ongoing crisis, with Ross Dam hovering around 15% of capacity most of the year, water restrictions at Level 3, and pumping from the Burdekin Dam always imminent even if not always under way. Our weak 2016-17 Wet hardly lifted the dam levels at all but an unseasonal May downpour (167 mm)  pushed the dam above 20% for the first time since August 2016.

Playing with the data so freely available online is fun, if sobering, and will show what’s going on better than another hundred words of text, so here’s the link to Townsville City Council’s dam levels page.

What the historical data can’t show, of course, is whether we’re going to get any decent rain in the coming months. Digging into the BOM climate outlook pages shows that they give us a 75% change of 300-400 mm in the next three months (which isn’t as much as we would like) but haven’t got a great deal of confidence in the accuracy of their prediction. “Wait and see” is all we can do.

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