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1. Assessment of winter season outlook (using BoM 3-,6-month decile maps)
On the 14 th September 2018 I issued my first outlook for 2019 with the statement “Rainfall likely to lean
towards below average in the 2019 winter growing season”. The first rainfall outlook map in February
2019 (Fig. 1A) showed below average rainfall for Western Australia, South Australia and Victoria, but more
average to below average rain in New South Wales and Queensland (note: I did warn that I was less
confident of average rain indicated for the two north-eastern States).The below average outlook stepped up
in early April as I refined a new suite of indicators to better predict the 2007 and 2018 droughts. In March
2019 two of these new indicators pointed to a very dry eastern Australia and a less severe Western Australia,
so analogues changed in April to reflect this (Fig. 1B). Forecasts remained below average for eastern
Australia for the rest of the year, but improved and were too optimistic in WA in early July and August (e.g.
Fig. 1d, e).
Actual rainfall for May to October matched the February Outlook for Western Australia and inland areas of
South Australia and Victoria, but was drier in drought affected areas in the east. Forecasts between April-
June predicted the national pattern of dry weather, but were overly negative for Victoria and not negative
enough for New South Wales and Queensland. In my commentary from early May I noted the very dry air
northwest of the drought region in New South Wales up to the Kimberly’s, so this seemed to amplify the
rainfall response as I suggested. Actual rain was drier than the below average outlook that I issued in early
August.
A fairly similar pattern of summer rainfall to what was forecast eventuated in the wheatbelt (Fig 2). However,
it was drier than predicted in in northern New South Wales, South Australia and parts of Victoria.
A. Long-lead 8 th February Predicted rain v Actual decile rain (May-October)
B. Medium-lead 3 rd April – Predicted rain v Actual decile rain (May-October)
.
C. Start of season 7 th May – Predicted rain v. Actual decile rain (May-October)
d. Mid-season 7 th August– Predicted rain v Actual decile rain (August-October)
e. End of season 3 rd September– Predicted rain v Actual decile rain (September-November)
Figure 1 AMA Predicted winter season rainfall deciles (left column) compared to actual (right column)
2 Assessment of Summer season outlook (using BoM 6-month decile map)
a. 13 th November 2018– Predicted rain v Actual decile rain (November 2018-April 2019)
Figure 2 Predicted summer 2018/19 rainfall deciles (left), right is actual November-April rainfall.
3 Comparison of crop forecasts assuming an average finish compared to
those assuming Agrometeorology Australia’s (AMA’s) seasonal outlook
Forecasts assuming average (left)
Forecasts assuming Seasonal Outlooks (right)
A) 1 st April 2019 – average rain AMA seasonal outlook rain assumed
B) 5 th May 2019 – average AMA seasonal outlook
Forecasts assuming average (left), Forecasts assuming AMA Seasonal Outlooks (right)
C) 3 rd June 2019– average AMA seasonal outlook
D) 1 st July 2019– average AMA seasonal outlook
E) 4/5 th August 2019– average AMA seasonal outlook
Forecasts assuming average (left), Forecasts assuming AMA seasonal outlook (right)F) 1 st
September 2019– average
AMA seasonal outlook
G) 1 st October 2019– average AMA seasonal outlook
Figure 3 AMA Predicted wheat yield rankings assuming an average finish (left column), compared to those
assuming Agrometeorology Australia’s seasonal outlook (right column)
Near final yield rankings : 4 th November 2019
Figure 4 AMA Near final predicted wheat yield rankings assuming an average finish (left column)
Crop yield rankings based on an average finish to the season (Fig. 3) were generally much too optimistic
compared to the near final rankings shown in Figure 4. Crop Yield rankings based on Agrometeorology
Australia’s seasonal outlook had a pattern that much better matched those in Figure 4. This pattern
emerged as far back as early April (Fig. 3A)
4 National and State wheat yield predictions: May to October 2019
The full sequence of national and State wheat yield predictions from early May are plotted in Figure 5. This
shows that yield forecasts based on the AMA seasonal forecasts were more accurate than those from
ABARES and those based on median rain for Australia, New South Wales and South Australia, especially in
New South Wales. In Western Australia and in Queensland the early May and June yield forecasts were more
accurate than ABARES and those based on median rain. However, crops being cut for hay (related to the
severity of the drought) in southern Queensland were probably the main reason the STIN crop model
overpredicted in this State. Victorian estimates were similar to ABARES early on in Victoria, but were too low
late in the season.
a) Australia b) New South Wales
3
2.5
90 %ile
Australian Wheat Yield Forecasts 2019
3.5
3
90 %ile
New South Wales Wheat Yield Forecasts 2019
50th %ile STIN model
90th %ile STIN model
10th %ile STIN model
Seasonal Forecast STIN
ABARES
Yield (t/ha)
2
1.5
50 %ile
Seasonal
Forecast AMA
Yield (t/ha)
2.5
2
50 %ile
1
10 %ile
50th %ile STIN model
90th %ile STIN model
10th %ile STIN model
Seasonal Forecast STIN
ABARES
1.5
1
Seasonal
Forecast AMA
10 %ile
0.5
0.5
5 6 7 8 9 10 11 12 13 14 15
Month
Year Year (+1)
5 6 7 8 9 10 11 12 13 14 15
Month
Year Year (+1)
C) Victoria d) South Australia
Victorian Wheat Yield Forecasts 2019
3
3.5
90 %ile
South Australian Wheat Yield Forecasts 2019
90 %ile
3
2.5
Yield (t/ha)
2.5
2
50 %ile
Seasonal
Forecast AMA
Yield (t/ha)
2
1.5
50 %ile
Seasonal
Forecast AMA
1.5
1
10 %ile
50th %ile STIN model
90th %ile STIN model
10th %ile STIN model
Seasonal Forecast STIN
ABARES
1
10 %ile
50th %ile STIN model
90th %ile STIN model
10th %ile STIN model
Seasonal Forecast STIN
ABARES
0.5
0.5
D)
5 6 7 8 9 10 11 12 13 14 15
Month
Year Year (+1)
5 6 7 8 9 10 11 12 13 14 15
Month
Year Year (+1)
e) Western Australia f) Queensland
2.5
2
Western Australian Wheat Yield Forecasts 2019
90 %ile
3
2.5
90 %ile
Queensland Wheat Yield Forecasts 2019
50th %ile STIN model
90th %ile STIN model
10th %ile STIN model
Seasonal Forecast STIN
ABARES
50 %ile
Yield (t/ha)
1.5
1
Seasonal
Forecast
10 %ile
50th %ile STIN model
90th %ile STIN model
10th %ile STIN model
Seasonal Forecast STIN
ABARES
GIWA
Yield (t/ha)
2
1.5
1
50 %ile
Seasonal
Forecast AMA
10 %ile
0.5
0.5
5 6 7 8 9 10 11 12 13 14 15
Month
Year Month (+1)
5 6 7 8 9 10 11 12 13 14 15
Month
Year Year (+1)
Figure 5 National wheat yield forecasts during 2019 for a) Australia, b) New South Wales, c) Victoria, d) South
Australia, e) Western Australia and f). Queensland. The seasonal forecast predictions are based on the median
of AMA analogue years. The 90 th (10 th ) percentile shows that 90% (10%) of years will have a yield lower than
that amount, while the 50 th percentile shows median yield prediction.
5 National and State wheat production forecasts: June to October 2019
The full sequence of national wheat production forecasts by Agrometeorology Australia and ABARES’s
through the 2019 growing season is shown in Table 1. Model forecasts based on median rainfall also shown
Month
Agromet Aust
ABARE
AMA
ABARE
Seasonal
Outlook(median)
(million tonnes)
(difference in
million tonnes)
(difference in
million tonnes)
June 15.6 (20.7) 22.2 +0.4 (+5.5) +7.0
July 19.8 (22.4) +4.6(+7.2)
August 17.8 (20.1) +2.6 (+4.9)
September 17.8 (18.9) 19.1 +2.6 (+3.7) +3.9
October 15.0 (15.3) -0.2 (+0.1)
November 15.4 (15.4) +0.2 (+0.2)
December 15.8 +0.6
February 2020 15.2 (final est.) -
Table 1. National wheat production forecasts during 2019 compared to final ABARE forecast (in yellow)
The Agrometeorology Australia (AMA) STIN model production forecasts were consistently more accurate
than ABARE forecasts, especially those based on the AMA seasonal outlook. In June this forecast was
close to the final result and was 6.4m tonnes lower than what ABARE was predicting. Mid-season
forecasts were slightly more optimistic, but final estimates in early October and November were all within
200 000 tonnes of the final ABARE estimate of 15.2 million tonnes.
Other estimates mentioned in the Australian Financial Review on the 21 st October were the NAB which
predicted 20 million tonnes of wheat in September (AMA, 17.8m) and 15.5m in October (AMA 15m).
Rabobank predicted 15.84m tonnes in October (AMA 15m). Some forecasters panicked in November
because of the drought and estimates went as low as 13 million tonnes.
New South Wales Wheat Production Forecasts in million tonnes compared to ABARES Predictions
Month
Agromet Aust
ABARE
AMA
ABARE
Seasonal
Outlook(median)
(million tonnes)
(difference in
million tonnes)
(difference in
million tonnes)
June 3.08 (5.55) 4.75 +0.99 (+3.46) +2.66
July 3.18 (4.95) +1.10 (+2.86)
August 2.92 (4.25) +0.83 (+2.16)
September 2.98 (3.40) 3.19 +0.89 (+1.31) +1.1
October 2.09 (2.22) 0 (+0.11)
November 1.98 (1.98) -0.11 (-0.11)
December 2.28 +0.19
February 2020 2.09 (final est.) -
Table 2. Agrometeorology Australia’s New South Wales wheat production forecasts during 2019 compared to
final ABARE forecast (in yellow)
Once again, the Agrometeorology Australia (AMA) STIN model production forecasts were consistently
more accurate than ABARE forecasts, especially those based on the AMA seasonal outlook. In June this
forecast was one and half million tonnes lower than what ABARE was predicting. Mid-season forecasts
were slightly optimistic, but final estimates in early October and November were all within 110 000 tonnes
of the final ABARE estimate of 2.09 million tonnes.
Western Australian Wheat Production Forecasts in million tonnes compared to ABARES
Predictions
Month
Agromet Aust
ABARE
AMA
ABARE
Seasonal
Outlook(median)
(million tonnes)
(difference in
million tonnes)
(difference in
million tonnes)
June 5.70 (6.41) 8.2 -0.10 (+0.61) +2.4
July 8.75 (8.29) +2.95 (+2.49)
August 7.51 (7.46) +1.71 (+1.66)
September 7.10 (7.60) 8.05 +1.30 (+1.80) +2.25
October 5.52 (5.52) -0.28 (-0.28)
November 6.00 (6.00) +0.20 (+0.20)
December 6.0 +0.20
February 2020 5.80 (final est.) -
Table 2. Agrometeorology Australia’s Western Australian wheat production forecasts during 2019 compared
to the final ABARE forecast (in yellow)
Once again, the Agrometeorology Australia (AMA) STIN model production forecasts were consistently
more accurate than ABARE forecasts, especially those based on the AMA seasonal outlook. In June this
forecast was two and a half million tonnes lower than what ABARE was predicting and was close to the
final estimate. Mid-season forecasts were too optimistic, especially in July when a wet June combined with
a more optimistic outlook to cause yield predictions to jump. This was the only month five analogue years
was reduced down to three analogues and was a classic case of forecasts being distracted by short-term
noise rather than longer term signals. However, final estimates in early October and November were all
within 280 000 tonnes of the final ABARE estimate of 5.8 million tonnes.
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