Hello, this is the Sugarcane Rainfall Outlook covering the southern sugarcane growing areas in
New South Wales updated on the 27th of April 2023. This Outlook will cover areas including Grafton,
Lismore and Murwillumbah and we'll first look at recent conditions, and then the
rainfall outlook for the coming fortnight and then the next six months out to October.
On the next slide on the right hand side there is a map showing the areas we're covering in this
Outlook particularly for those areas in the New South Wales sugarcane growing areas.
On the left rainfall totals for the month of April to the 25th of the month for selected
locations and we can see here 106mm for the month at Grafton Airport, 46mm at Lismore Airport and
just 18mm at Murwillumbah, so for some of these areas particularly inland from the coast rainfall
has been very much below average. For example in Lismore the average for April is 111mm.
The next slide is looking at the chance of exceeding median rainfall in May on the
left hand side and then June to August on the right hand side. In May there's the low chance
of exceeding median rainfall as indicated by these brown shades, meaning it's likely
to be a drier than average month. From June to August it is looking to be an equal chance of
exceeding median rainfall, we can see a shift to these white shades indicating that sort of
40 to 60% chance of exceeding median rainfall, so looking like a 50/50 chance at this stage.
On the next slide we're looking at model accuracy based on past performance at that time of year,
and in particular what we're seeing here is the percentage of times that the model
has got it right for this period. In May median rainfall forecasts are typically correct 55 to
65% of the time for these areas in northern New South Wales as indicated by these green shades
and June to August we see the models typically correct 65 to 75% of the time
so a slight increase in skill for these areas of northern New South Wales growing sugarcane.
On the next slide we're looking at rainfall for the next two weeks and specifically the chance of
exceeding 25mm each week for the next two weeks. For the week of April 30 we see some areas do have
at least a 25% chance of exceeding 25mm along the coast and that's due to some showers and
storms coming through on both the 29th and 30th this month which I will show later on.
However from the first week of May it is looking dry you can see the chance of exceeding 25mm drops
back to generally below 25% so that rainfall coming through this week is looking like a
higher chance of exceeding 25mm. On the next slide we're looking at rainfall for the rest of May.
On the left the 50% forecast chance versus the historical median on the right hand side,
and just eyeballing the two we can see that the 50% chance outlook is drier
than the historical median and you can see that just by comparing the shading
on each map on each side showing that the forecast 50% chance is quite a bit less than the historical
median and that of course reflects that dry outlook for May you saw previously.
Next looking at the 75% chance or high chance of receiving at least compared to the 25% or lower
chance of receiving at least and the best way to think about these maps is that it is showing the
same rainfall range as what you see in the BOM app in that rainfall range. For example Lismore it is
showing that there's a high chance of receiving somewhere between 25 and 50mm for the month of
May and at a lower chance of receiving more than 100mm so it is showing that 50% block of scenarios
For the rainfall outlook for June we're looking on the left hand side the 50% forecast chance
again versus the historical median on the right hand side. Similar to May the
50% chance is looking drier just by comparing those colours on the left and right hand maps.
And again looking next at the 75% high chance versus the 25% low chance for the month of June
On the next slide we're looking at the three months this time from June all the way to August,
again comparing the 50% forecast chance on the left-hand side to the historical median.
And we are looking that it is generally on the drier side than the historical
medium particularly south of about Ballina and towards Grafton as you can see here,
but further north particularly towards the Queensland Coast the colours are pretty similar
indicating that we are looking to see around the historical median for the three-month period.
For the next slide again looking at that 75% high chance to the 25% low chance or 50% middle range.
As we look ahead to Spring at this stage it's probably a bit too early to give a confident
forecast this far out, but as we release updates closer towards Spring we will have a better idea
of what's to come. The maps you see here are the historical median based on data from 1991 to 2020.
and at this stage international models that do go this far out do indicate the possibility of
being drier than average being the more likely scenario from September so not seeing these
rainfall medians being realized for spring but of course we will know more further on.
Finally the short-term weather watch points, what you're seeing here are 24-hour rainfall totals
to both Saturday night and Sunday night of this week and we have this system coming through from
the west of New South Wales most of the rainfall will be to the west of the Great Dividing Range
so at this stage that north New South Wales sugarcane growing area not expected to see
those high rainfall totals and that's why the chance of seeing 25mm was generally 50% or less
and we do see that rainfall push across the east coast into Sunday but then it does move completely
offshore on the 1st of May. But as always check the latest forecast and warnings on the Bureau's
website or the BOM weather app through the week. That's it for this Outlook be sure to send your
feedback through to agriculture@bom.gov.au and we'll see you next outlook, thanks for listening