Climate Outlook Accuracy

All general weather related discussion & questions, including model discussions, longer-term outlooks & anything non-breaking weather.

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Gordon
Supercell
Posts: 2031
Joined: Thu Jun 17, 2010 10:01 am
Location: Near Gordon, Vic. 620 m asl

Fri May 31, 2019 2:59 pm

After some discussion in the regular weather threads, thought it might be useful to start some comparisons.

I don't intend this to be a 'bag the NCC' thread but I do think there needs to be a discussion about whether a bad forecast is better than no forecast. In other words, should forecast accuracy be a certain standard before an Outlook is released to the public with considerable fanfare? I believe no Outlook is preferable because even with the riders regarding accuracy, people largely go ahead and plan and act as if the Outlook were fact or at least very likely. Fair enough - the average person may ask why an Outlook is being trumpeted if it isn't very likely to come true? Here's the May 2019 effort:

Forecast issued 26 April:
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Actual May rainfall:
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Gordon
Supercell
Posts: 2031
Joined: Thu Jun 17, 2010 10:01 am
Location: Near Gordon, Vic. 620 m asl

Tue Jul 02, 2019 7:39 pm

Forecast for Vic for June 2019...

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And actual...
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So far, the climate forecasts (rainfall) have failed - at least for our part of Victoria - every month this year.
JasmineStorm
Supercell
Posts: 1868
Joined: Thu Sep 22, 2016 9:40 pm
Location: Kyneton 527 ASL

Wed Jul 03, 2019 12:01 pm

Yes Gordon agree, that is a major miss again. One dimensional outputs from Access S missing the wettest Autumn break 2 month period in 24 years locally. MJO pulses and Negative SAM's were as clear as day before each Access S run was executed at the end of April and May. It was a classic climate set up for big NW moisture laden prefrontal flows into the northern slopes which also had some southerly flow on the other side.
Gordon
Supercell
Posts: 2031
Joined: Thu Jun 17, 2010 10:01 am
Location: Near Gordon, Vic. 620 m asl

Sun Aug 18, 2019 5:12 pm

This is why I get so passionate about the continual poor quality of the climate outlooks - at least for certain parts of the country like ours. No matter how BOM dresses it up, people who make major decisions affecting all of us, particularly water managers, treat these forecasts as if they are fact. Until or unless accuracy improves, they shouldn't be issued. A bad forecast is more harmful than no forecast. Check out the acting Premier's quote in the second article!!

From the Geelong Advertiser 10 July:
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Note that I don't object to more research on climate outlooks - the more the better. It's the public issuing of these forecasts & associated BOM headlines that are the problem.

BTW Geelong's water supply is now at 62%, ahead of the same time last year.
Last edited by Gordon on Mon Aug 19, 2019 12:20 pm, edited 1 time in total.
JasmineStorm
Supercell
Posts: 1868
Joined: Thu Sep 22, 2016 9:40 pm
Location: Kyneton 527 ASL

Mon Aug 19, 2019 12:15 pm

Nice reading Gordon :) I actually only read the BoM's monthly outlook now for comic relief. As pointed out before, Access S is not factoring SAM into winter rainfall outlook for certain areas of Victoria, which could be done before the end of each month. Their rainfall forecasts have been a 100% bust for here locally. Upper Coliban dam is now spilling and the Coliban water storages as of this morning are now 88%, up 6 % from this time last year :hysteria:
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Gordon
Supercell
Posts: 2031
Joined: Thu Jun 17, 2010 10:01 am
Location: Near Gordon, Vic. 620 m asl

Mon Aug 19, 2019 12:23 pm

Thanks JS. Btw I just edited the second newspaper page to make the Minister's quote easier to find. If a minister, supposedly with access to the best advice, 'knows' it's going to be very dry, what hope does the average person have?
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