How Reliable is the Bureau’s Heatwave Service?

The Bureau of Meteorology presents heatwave assessments and forecasts in the interest of public health and safety.  Their heatwave definition is not based on any arbitrary absolute temperature, but uses a straightforward algorithm to calculate “excess heat factors”.  From their FAQs:

“Heatwaves are calculated using the forecast maximum and minimum temperatures over the next three days, comparing this to actual temperatures over the previous thirty days, and then comparing these same three days to the ‘normal’ temperatures expected for that particular location. Using this calculation takes into account people’s ability to adapt to the heat. For example, the same high temperature will be felt differently by residents in Perth compared to those in Hobart, who are not used to the higher range of temperatures experienced in Perth.

This means that in any one location, temperatures that meet the criteria for a heatwave at the end of summer will generally be hotter, than the temperatures that meet the criteria for a heatwave at the beginning of summer.

……

The bulk of heatwaves at each location are of low intensity, with most people expected to have adequate capacity to cope with this level of heat.”

Back in 2015 I showed how this algorithm works perfectly for Melbourne, but fails to detect heatwaves in Marble Bar and instead finds heatwaves at Mawson in the Antarctic.  In light of the long period of very hot weather across most of western Queensland, what does the Heatwave Service show?

Here is their assessment of conditions in Queensland over the last three days….

Fig. 1: Heatwave assessment for 21-23 January 2019

heatwave assessment

Most of inland Queensland has been in a “Low-Intensity Heatwave”, with a couple of small areas near the southern border of “Severe Heatwave”.

And here is their forecast for the next three days..

Fig. 2:  Heatwave forecast for 24-26 January 2019

heatwave forecast

Much the same, with a bit more Severe Heatwave coming.

So what were temperatures really like in the previous three days? Here’s the map for the middle of that period, Tuesday 22nd:

Fig. 3:  Maximum temperatures for 22 January

max 22 jan 1 day

About half the state was above 39 degrees C, a large area was above 42C, and there were smaller areas of above 45C.

And in the past week:

Fig. 4:  Maximum temperatures for 7 days to 23 January

max 22 jan 1 week

Average maxima for roughly the same areas were the same, except there was a larger area averaging over 45C!

This follows December when a large slab of the state averaged from 39C to 42C for the month.

Fig. 5:  Maximum temperatures for December 2018

max 22 jan 1 month

I’m focusing on Birdsville, circled on the map below (and indicated on the maps above.)

Fig. 6:  Queensland forecast towns- Birdsville indicated

qld map

Here are the maxima for Birdsville for January:

Fig. 7:  Birdsville Maxima for January

birdsville jan max

And here’s the forecast for the next 7 days:

Fig. 7:  Birdsville 7 Day Forecast

birdsville forecast

Apart from the 6th, when it was a cool 38.8C, since Christmas Eve the temperature has been above 40C every day, and is forecast to stay above 40C until next Tuesday (and above 45C until Sunday).  Minima have been above 25C on all but three days since Christmas.

And that’s a “Low Intensity” heatwave, with “most people expected to have adequate capacity to cope with this level of heat.”

The Bureau’s unspoken message?  It might be a bit hot, but you’re supposed to be used to it.  Harden up!

Western Queensland residents are pretty tough, but surely a month of such heat deserves a higher level of description than “Low Intensity”- especially for the vulnerable like babies, old people, and visitors.

This is worse than laughable.  The Bureau’s heatwave service is a crock.  As I said in my 2015 post, a methodology that fails to detect heatwaves at Marble Bar (or Birdsville!), and creates them in Antarctica, is worse than useless- it is dangerous.

Advertisements

Tags: , , , , , ,

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s


%d bloggers like this: