Australia’s warmest 12-month period on record- NOT

Ken Stewart

September 2013

Australia’s Bureau of Meteorology (BOM) was quick off the mark earlier this month when it proclaimed:

“Australia’s warmest 12-month period on record

September 2012 to August 2013: the last 12 months

The past 12 months have been the warmest on record for Australia. The average temperature across Australia for the period 1 September 2012 to 31 August 2013 was 22.92 °C. This is 1.11 °C above the 1961–1990 average, surpassing the previous record of +1.08 °C that occurred between February 2005 and January 2006.”

The satellite data for the mid-troposphere for Australia- Land has just been released by the University of Alabama- Huntsville (UAH).  Unfortunately analysis of this data shows that the mean temperature for the 12 months to August 2013 was +0.668 Celsius, which makes this period the sixth warmest of the satellite era (since December 1978).

That’s 0.087 below the record set in the 12 months to June 2010.

Here is a graph of the 12 month running mean to August 2013:

Yes, it has definitely been warm.  The Sub-Tropical Ridge being so far north, and the dry conditions in the northern inland, may have something to do with that too.

The Bureau expects temperatures for the rest of the year to be above average, and claim that

“If a mean temperature of more than 1.0 °C above average is maintained over the next one-, two-, three- or four-month periods, each of the 12-month periods ending September, October, November and December would exceed the previous record from 2005–06 for the warmest 12-month period.”

On the other hand, if  UAH records data for the Australian region of +1.0C for the next four months, the 12 months to December will be +0.748, the warmest calendar year on the UAH record, but still in third position for the 12 month mean.

And there is no doubt that this could happen.  But only in 2006 and 2007 were there a total of just three months out of 12 above +1.0C, not five in a row.  I’m not holding my breath.

It depends which data you would trust, from satellites criss-crossing the globe 24 hours a day, or from 104 scattered stations recording a daily maximum and minimum.

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September -December Weather Predictions

At the beginning of August my predictions for sub-tropical Queensland (St Lawrence to Longreach and south to the border) for August were:

2-3-4-5-6-7, 9-10-11-12-13, 15-16-17, 19-20-21-22, (24-25-26?) –27-28-29-30.

Results:

There were weather events on August 2, 6-7-8, 12-13-14, 16, 18-19-20 (with some rain on 17th, recorded 18th), 29-30-31.

Predictions were not as good in August, with only 6 out of 8 unequivocal successes, with 1 complete miss and 1 doubtful, and a couple merged together.

Here’s a (rather noisy) plot of August data.

I have highlighted changes that matched predictions and the 24-25-26 miss.

I have also indicated with green bars the likely times for weather changes in September.

Predictions for the rest of the year are as published on previous posts.

A vigorous change came through the Capricornia district today, and further events are expected on:  4, 7, 9-10, 13, 16-17-18, 23-24-25, and 30- October 2.

Another update in a month’s time.

PS- Google Chrome solved the problem with uploading images!