Below average rainfall has been a worrying theme that has continued over the last couple of months. Nearly all weather stations throughout the grainbelt received below average rain throughout August, with parts of Northern NSW and southern Queensland barely registering a drop. Temperatures had been a touch cooler, however the start of spring has seen a warmer bias emerge. The short term forecast remains dry, which will continue to trim yield potential in northern regions. Some recent frosts in Nth NSW / Sth QLD regions may pose some concerns with flowering crops, but a lot of the crops are running late.
A sprinkling of rain occurred late last week (5 –7mm), but August will be the first month of the year where weighted cropping regions received below average rain in QLD. Although August is usually the driest month of the year, timely rain is needed especially after many parts received minimal rain over the last six weeks. Monthly rainfall was 9mm, which was 8mm below the norm, while some isolated regions throughout CQ received up to 47mm, but was in isolated spots. Thanks to a very wet start to the year GSR (April - Aug) is still 50mm above the norm of 105mm.
For the first time this year, it seems all the wet weather was in the south of NSW. The once dry Murrumbidgee region had good rainfall (36mm) which will help build up yield potential. Northern parts of the state only received around 8mm, which is a 22mm deficit. Actually it would be the first month of below normal rain since April, so it is not panic stations just yet. But as we enter the crunch time of the year timely rain is needed to maintain the good start. State GSR (142mm) is running at a 23mm deficit.
Another month of below average rainfall in VIC, with a 15mm deficit. And although key production regions of the Mallee and Wimmera had some handy rain, is was still 16 to 20mm behind the norm. The Western District continues to see good rainfall; but bear in mid this region accounts for 4% of state output. GSR (152mm) is running at a 41mm deficit. Back to back dry months in SA, with all cropping regions having below normal rainfall. The EP and York/Mid North both had a 20mm deficiency. These two key regions account for 60% of state output. In lieu of the recent BoM forecast future rainfall prospects could be drying up. GSR (177mm) is at a 25mm deficit.
August started with a bang in WA, with good rainfall in the first week, but since then only passing showers have occurred. Most regions have had between 30 - 38mm, but still 20mm short of the norm. With GSR deficits of around 100mm though key production regions the short moisture profile will soon be evident on rapidly growing crops. Some welcome rain throughout WA overnight, although it was concentrated along coastal and southern regions, follow up showers are expected to linger throughout the day.
Erratic patterns are emerging from the SOI index. After a +10.3 swing through July, August has been all over the shop. Nudging -23 at the start of the month, before bouncing back to +14 for an overall monthly average of -6.2. This compares with +0.1 in July and -10.2 in June. Remember that an El Niño event is sustained values of -8.
Other indicators such as trade winds and tropical cloud patterns have yet to clearly indicate a typical El Niño pattern and would explain the erratic data. But, the equatorial Pacific remains warmer then average and this usually favours below-average rainfall over eastern Australia. Models are also pointing to a return to neutral conditions in early 2013.
The BoM outlook continues the theme from last month with a concerning dryness pattern lingering in SE Australia. The entire SA cropping region is forecast to only have a 30% chance of exceeding median rainfall. Victoria and parts of southern NSW have also been tarred with the same brush of a sharply drier rainfall bias. It doesn’t offer much hope for parched paddocks that have been chasing moisture all year. Combined with warmer then usual temperatures forecast, this could be the death knock if sharply below average rain do eventuates. Previously the BoM outlooks for WA have been spot on in calling a dry winter. Well the tables have turned and it seems there could be some upside potential. However the timing would be the critical part of this. With many parts not having any substantial rain in more then a month, rainfall needs to be soon before irreversible damage has been done in the north.