Desperate for a Record

During the current heat wave, the Bureau of Meteorology (BOM) have been speculating about the likelihood of maximum temperature records being broken, including Queensland’s record of 49.5 degrees Celsius set in Birdsville on 24/12/1972.

Birdsville is a tiny but well known outpost in the far south west of Queensland.  The nearest other site is Bedourie 170 km away, but it has no data from before 1998.  There are no records for comparison on CDO within 290 km.

The Acorn record starts from 10/5/54, which according to the metadata is when observations commenced. On Climate Data Online Birdsville Police Station record starts on 1/1/57.  Where is the missing data?  It’s no excuse to say it hasn’t been digitised from the paper records because it obviously has been digitised into Acorn.  It should be fairly straightforward to copy it from Acorn into CDO.  By contrast, Brisbane has CDO data from the old Regional Office from 1887 yet Acorn’s creators have chosen to exclude this early data before 1948.

Acorn uses Police Station data exactly until the Airport site opens on 29 June 2000 when it adopts the Airport data exactly, with no adjustment despite good overlap- with occasional exceptions.  (Airport data is slightly less than Police Station data by on average 0.1 C.)

Before 1 September 1972 Police Station data was recorded in whole degrees Fahrenheit, therefore the uncertainty is +/- 0.3 C.  In the months following 1 September 1972, the date of metrication, temperatures are recorded in whole and half degrees Celsius, so the uncertainty is +/- 0.25 C.  Queensland’s “record” maximum temperature was recorded at Birdsville on 24 December 1972, so the actual temperature on this day could have been between 49.2 and 49.8C.

When the Airport site opened and its data used by Acorn, it was recording temperatures in whole degrees Celsius only, and the uncertainty then was +/- 0.5C.

Second highest temperature was 49C on 6/12/1981.

The next highest temperatures were 48.8 on 22/12/1990, and 48.7 on 17/11/90.

Interestingly, there are 5 other recordings of the next highest temperature, 48.5C, on 23/12/1973, 5/12/1981, 5 and 6 January 2004, and 30/11/2006.  Despite having an Airport recording of 47.9C on 5 January 2004, Acorn has chosen to use the higher Police Station recording instead of the Airport.birdsville max jan04

So the more extreme temperature was chosen!

Despite all expectations of the record being broken, the highest BOM could get out of Birdsville this summer has been 47.3C on 4 January.  That’s 19th, and not even close to the record.

To put this in context, taking 35 C as BOM’s latest standard for heatwave conditions, 34.4% of Birdsville’s maxima are 35C or more.  Birdsville’s January mean is 40.2 degrees.

Why has the BOM been so concerned and excited about the possibility of breaking maximum records?  This graph of the 365 day running mean of Birdsville maxima might give a clue:birdsville max acorn

They’re hoping temperatures will get back up to where they’re supposed to be, otherwise that trend line of nearly 0.25C per decade will change a bit.

Conclusion? They’re desperate and dateless.

5 Responses to “Desperate for a Record”

  1. John Westman Says:

    Good day Ken,

    With all the hoopla associated with the recent hot weather I decided to do some inquiry on earlier records. My mother constantly reminds me, about brutally hot weather in the 1930s.

    The current weather station(for Wagga) started recordings in 1948(AMO 072150); so I have had to look at other station data, especially Kooringal(072151-now closed. Records available to 1952). The interesting thing about Kooringal is that, while I don’t know the actual site of the station, Kooringal itself is sheltered by a large north/south running hill, which would have protected the station somewhat from the westering sun. I was able to compare overlapping data for the years 1943-1950(8 years) to obtain the anomalies between the two. The anomalies were quite consistent varying between .9 and 1.2 degrees C. Average was 1.01 degrees C. with Kooringal being the warmer.

    To mention some of the extreme weather in the Kooringal record(I have not adjusted for the average anomaly)

    1896 13 days =/over 40 C for January. January mean monthly max of 38.1 C

    1897 6 days =/over 40 C for January Maximum temperature recorded of 47.2 C

    1898 January monthly mean of 38.7 C 12 days =/over 40 C, for January 9 days =/over 40 C for February

    1932 January monthly mean max of 36.2 C 9 days =/over 40 C for January 1939 January monthly mean max of 37.7 C 11 days =/over 40 C for January 9 consecutive days =/over 40 C for January

    1946 January monthly mean max of 34.0 C 7 days =/over 40 C for January 6 consecutive days =/over 38.0 C.

    This exercise just goes to show that the current hot spell is nothing unusual and has happened before. While I have only used data from Wagga, I expect that it would be representative. By the way, the average long term daily max for January in Wagga is 31.5 C, approximately. The dates could be clues for other people to run some checks on other locations

    Feel free to circulate if you think appropriate.

    Regards,

    John Westman

    3/5 Narrung Street, Wagga NSW 2650. 02 69 215 905; 0432 827 254

    • kenskingdom Says:

      Gday John

      Yes Wagga Wagga is an interesting location. The reporting of this heatwave was ridiculous, it was hot but not to record levels. The purple patch on the temperature map certainly didn’t eventuate. There were bad bushfires in Tasmania 40 years ago, burnt into Hobart suburbs, but that’s long forgotten.
      Ken

  2. justthefacts62 Says:

    Interesting to note that some of links cited on the Climate Commission “Off the charts” report, are outdated Bom links.

    One might think that this report may have been prepared well in advance and released for maximum effect within a day or two of the “extreme” heat event.

    Ps Currently 15°C and raining here in Adelaide.
    JTF

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