The last few days have brought us some genuine early-Wet weather: heat, humidity and thunderstorms. We have recorded our first double-digit rainfall totals in months, so it feels like a good time to see what really happened last year.
The BoM released its Annual Climate Statement for 2019 a fortnight ago. It named last year as Australia’s warmest and driest on record but there were notable local exceptions: Townsville (1761 mm) and the middle of Western Queensland scored their wettest year on record. (So did the tip of Cape York, one spot on the WA coast and one spot on the Tasmanian coast, which reinforces the feeling that our weather is getting ever crazier but is not otherwise relevant here.)
Four years ago I divided our years into “dry”, “wet” and “average”. By that simple measure, 2019 was very clearly a “wet” year, but that label masks the fact that almost all our rain came in two discrete events, the fortnight of the floods and a week at the end of March.
A map on the BoM’s Drought page shows that our August-December rainfall was the lowest on record, and the daily stats show that we only received 80 mm between the end of March and the end of the year.
The outlook for 2020
What’s on the horizon? The BoM regularly publishes weather outlooks and their latest summary (Jan 16) says:
- The chances of a wetter or drier than average February to April are roughly equal for most of Australia.
- Daytime temperatures for February to April likely to be above average across almost all of Australia except the southwest, with February to April nights very likely to be warmer than average for most of the country.
- The positive Indian Ocean Dipole (IOD) and the negative Southern Annular Mode (SAM) phase have ended, meaning most climate influences are now neutral.
Their past accuracy has been very good (they publish it on the same page but their links often change so I won’t share this one) so I’m sure they are right in general terms.
We are certainly in for a warm year. We would know that even without the BoM forecast, since (as this poster shows so graphically) global warming is continuing unabated. As the annual climate statement says:
The mean temperature for the 10 years from 2010 to 2019 was the highest on record, at 0.86 °C above average, and 0.31 °C warmer than the 10 years 2000–2009. All the years since 2013 have been amongst the ten warmest on record for Australia. Of the ten warmest years, only one (1998) occurred before 2005. Warming associated with anthropogenic climate change has seen Australian annual mean temperatures increase by over one degree since 1910. Most of this warming has occurred since 1950.
However, Townsville’s Wet-season rainfall is so wildly erratic that we still don’t know how much to expect. Local folk wisdom has long said that, “We don’t get a good Wet unless we get a cyclone,” to which we must now add, “or a rain depression,” but it’s probably more useful to say that these big events are superimposed on a dry, wet or average year.
In those terms, 2019 was a very dry year with a rain depression; 2020 looks like being a more normal year overall, but we won’t know about any big weather events until they arrive.