Forecast 28°
– weather turned out 25°
Apologies – I initially posted the forecast at 35deg which was wrong – it was 28.
The 35 degrees is tomorrow, Wednesday.
– In January I commented on an 8° fail. Australian Bureau of Meteorology Sydney temperature forecast 12 Jan 2013 – another amazing failure
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Fascinating to check tonight what gets said on TV weather news.
Sydney region forecast link –
Actual weather link – several days are kept.
Good catch. I couldn’t understand such a bad fire day predictions when there has been an obvious massive cold front coming for the last week.
I did a study of capital city forecasts about 18 months ago. It involved collecting the predicted seven-day maxima and minima over a four month period and comparing them to actual observations. As expected the largest errors were those from predictions a week ago and they improved more or less linearly as the number of days ago of the estimate decreased. (Note that in the following comments no distiction is made as to whether it was an over or under estimate.)
For maximum temperature the mean error from seven days ago was around 3 degrees C for Perth, Melbourne, Hobart and Adelaide, around 2.5C for Canberra and just over 1.5C for Sydney and Brisbane. (The BOM only forecasts four days out for Darwin.)
For forecasts made “yesterday” the error was about 1.7C for Hobart, 1.25C for Melbourne and Canberra and around 1.1C for Sydney, Adelaide, Perth and Brisbane. Darwin came in at 0.9C.
For minimum temperature the error from seven days ago was just over 2C for Perth, Canberra and Adelaide, around 1.5C for Hobart and Melbourne and around 1.2C for Sydney and Brisbane.
Yesterday’s minima forecasts were out by about 1 degree for all cities except Perth (1.3C) and Canberra (1.8C).
The study period was 28 November 2011 to 22 March 2012 and included 102 days of complete 7-day forecasts. During this time the biggest “discrepancies” from yesterday’s forecasts were:
Adelaide, min 4.7C, max 5.7C
Brisbane, 3.4, 4.5
Canberra, 4.4, 5.6
Darwin, 4.1, 3.3
Hobart, 3.4, 5.5
Melbourne, 4.2, 6.5
Perth, 6.2, 4.8
Sydney, 2.4, 3.6
I’ll send the working file, with graphs, to the group.
This is part of a systematic and deliberate policy, it is not an accident. What people remember is the frightening headline. It is very similar to the ongoing systematic upward adjustment of the temperature record in all Climate Data Sets. Invariably the past is cooled and the present is warmed and the influence of UHI is totally ignored.
Because the followers of CAGW are running out of factual information backing their position, they are resorting to well-tried propaganda methods, The ABC’s attempts to link the current bushfires to Climate Change amd the Carbon (Dioxide) Tax are in the same basket.
Interesting to see your results, thanks Ian – and your survey covered all the State capitals for the summer of 2011-12. Your 102 days is the largest sample I am aware of.
“This is part of a systematic and deliberate policy” .. it is all a conspiracy, huh?.
Right now temperatures at Sydney stations are just over 31-33.
But at Mt Boyce near Blackheath – not far from the Mt Victoria fire – at 1.34pm it is only 20.1. Pity there are not more real time recorders up on the heights.
This morning around 10.45am I noticed several stations out in the far west, Broken Hill, White Cliffs etc were reading around 20 after conditions had cooled overnight compared to previous nights.
Thanks Warwick. I didn’t see any point in collecting just a couple of weeks data and went for 100 days, but at the same time I was glad to stop! I’ve now distributed further results. Briefly, the BOM gets it right, to within 1.5C, about 75% of the time when the forecast is made the previous day. The first forecasts for any day, made a week previously, are within that accuracy about 58% of the time for minima and 42% of the time for maxima. As can be seen, they predict the minimum temperature more accurately than the maximum.
Some cities vary significantly from that. Hobart has only a previous-day 49% maxima prediction rate to within 1.5C and Canberra a 49% minima prediction rate.
When forecasts are that accurate there is a clear tendancy to forecast maxima on the cooler side in Adelaide, Brisbane and Darwin. When forecasts are unsatisfactory (error > 3.5C) the tendancy is to forecast on the warmer side.
BoM forecasting 32C for Perth today. Seems unlikely as currently <18C.
Philip
Strong low level temperature gradient today – ergo the gusty E’ly winds and moring mid level thunderstorms (a quick refresher on quasigeostrophic theory will assist here). You can go around the net and sample other opinions .. we’ll see who is correct:
BoM 32
Google 27
Accuweather 30
Weather.com.au 31
Wunderground 29
World Weather Online 29
Just now it is looking like Philip Bradley 1 — BoM 0 –
Checking a range of stations here from 11am on – 32 never looked to have much chance with many sites inland of Perth being in the 20’s. Eg. Cunderdin.
There are a few plus 30’s, Dalwallinu, Morowa, but none in the Lower West grouping.
Top for the day in Perth was 27.9 at 3.20 pm.
Copying the ABC method: pindanpost.com/2013/10/25/scary-headline-500-of-october-average-rain-in-half-an-hour/ 5 times average October rain in 30 minutes …