Climate update – August 9

Climate update – August 9

Cattle National
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Climate & Agricultural Support's Melissa Rebbeck discusses likely weather conditions for SA's agricultural regions in the coming weeks and months.

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Climate & Agricultural Support's Melissa Rebbeck discusses likely weather conditions for SA's agricultural regions in the coming weeks and months.

August 9

Most of SA recorded decile 2-3 rainfall for May through to the end of July.

The remainder of Australia recorded decile 2-3 with some parts recording decile 1 or lowest on record.

The next week across SA is likely to be 7-14 millimetres drier than normal at your location, according the to the BOM POAMA model.

Present ocean and atmosphere conditions are not entirely negative for rainfall to transpire, but the BOM continues to warn that an El Nino may develop by spring with double the normal chances, according to their dynamical models.

If this occurs, then there are increased chances for below normal spring rainfall. 

August 2

For August, there is a less than 30 per cent chance of exceeding the median rainfall for much of the state’s cropping zone.

In addition, much of the state has a 70pc change of exceeding the median maximum temperatures for August (according to the Bureau of Meteorology seasonal outlook). 

Much of SA has a suite of soil moisture probes that can be accessed here.

Stored soil moisture can be used in conjunction with seasonal outlooks to project pasture and cereal production.

There are outlook tools that already do this such as the Meat and Livestock Australia rainfall to pasture growth outlook tool or Yield Prophet.

July 26

Rainfall for April to June has been very much below average in the decile 2-3 range for most of SA.

The remainder of Australia has similar circumstances with some areas like southern WA receiving rainfall at the lowest on record.

I cannot help but relate the recent southern Australian rainfall patterns to that of rainfall patterns across the past 20 years.

Autumn rainfall for southern Australia has been on the decline on average for the past 20 years, when compared to the last 100 years of rainfall.  This is due to larger than normal high-pressure systems blocking cold frontal development and movement across SA.

Going ahead it is best to make farm decisions on rainfall to date, stored soil moisture, a neutral winter outlook and a potential El Nino and positive IOD for Spring (meaning below normal rainfall more likely).

July 19

The next week is more likely to be drier than normal across SA according to the Bureau of Meteorology POAMA model, with about normal rainfall more likely for August.

There are no strong indicators for above normal rainfall beyond August, with sea surface temperature that influence above normal rainfall being neutral and the Southern Oscillation Index unlikely to encourage the movement of warmer water to the Pacific Ocean above Australia.

The BoM warns of double normal chances of an El Nino developing in spring and half of the ocean and atmosphere models also suggest a positive Indian Ocean Dipole. If either of these things occur our chances of receiving above normal rainfall for spring across SA will be reduced. If both occur together the chances diminish further.  

June 14

You may be aware of the new fast break and a series of excellent seasonal climate products available for SA. The fast break mentions the present blocking high over the Bight, chasing fronts and lows away and, of such strength, that its movement eastward is painfully slow.

This large high is also having an impact on the water temperature in the Timor Sea, where stronger easterly winds are stirring the surface up and making it the sea surface temperatures cooler and hence less moisture available for rainfall.  All these things are hopefully temporary, but until they change, dry conditions seem likely.

June 7

The Bureau of Meteorology’s outlook for winter is 45 per cent statistically consistent for SA. The BoM does provide the accuracy information on their web page by clicking a link near their seasonal outlook.  

The BoM has a duty of care to anyone utilising these outlooks to provide an understanding that guessing or tossing a coin would be more accurate than the present winter BoM outlook for SA. 

The reason the outlook is not very consistent at this time of year is due to a lack of strong signals in the ocean or atmosphere with broadscale climate drivers, such as the El Niño–Southern Oscillation and the Indian Ocean Dipole forecast to remain neutral during winter with little influence on SA rainfall.

Despite the lack of accuracy, the outlook does show reduced chances of above median rainfall for winter for most of SA.

I think the best bet for agricultural decision-making at present is to not place any emphasis on this outlook for now and instead use stored soil moisture and the BoM met eye outlooks for 10 days to better inform decisions.  

May 24

The ocean to atmosphere indicators suggest neither a wetter or drier than normal winter.

The season could go either way. Due to the lack of conciseness with the current indicators, I have resorted to probabilities of rainfall. Across these locations here are the probabilities of receiving 50mm for June; Adelaide 70pc, Renmark 4pc, Whyalla 12pc, Port Lincoln 87pc,  Keith 50pc, Mt Gambier 97pc, Mt Compass 83pc, Nuriootpa 60pc, Minlaton 62pc, Strathalbyn 40pc.  The POAMA experimental model suggests June rainfall is more likely to be around normal for the southern coastal regions of SA and slightly below normal for the remainder of the state.  

May 17

A slow moving low high-pressure system is likely to block rainfall for the next 7 days across SA.  The POAMA experimental model suggests that rainfall is more likely to be up to 15mm below normal for the next two weeks. The southern annual mode SAM used to interpret the potential strength and position of cold fronts and mid-latitude storm systems was negative over the last week bringing welcomed cold fronts, “the Antarctic blast” however the SAM has returned positive and more likely to remain that way for a week or two meaning more high-pressure systems over southern Australia for that time.  

May 10

Most climate drivers are having little influence on our rainfall at present with normal sea surface temperatures and a current neutral ENSO (El Nino Southern Oscillation). 

This means that rainfall can go either for the coming months way but less likely to be extremely dry or wet.

But, the Southern Annular Mode (SAM) is more likely to be negative over the coming weeks.  SAM can be used to interpret the potential strength and position of cold fronts and mid-latitude storm systems and is an important driver of rainfall variability in southern Australia.

A negative SAM event reflects an expansion of the belt of strong westerly winds towards the equator and this means more (or stronger) storms and low-pressure systems over southern Australia and hence likely rainfall.

This would be a welcome change to the warmer than normal days and cold nights provided by the dominating blocking high pressure system in the upper atmosphere over the last week. 

May 3

There are no strong swings toward above or below normal rainfall for May to June for SA.

The sea surface temperatures that can influence rainfall at this time are neutral and are likely to stay this way through winter.

This does not necessarily mean average conditions will result, it means that the ocean and atmospheric condition are difficult to read at present, so the outlook models cannot indicate which way the rainfall is more likely to swing.

In the shorter term, there is up to 20 millimetres coming in the next few days for the southern parts of SA.

Soil Moisture probes are being used more for irrigation scheduling, prediction of pasture and crop growth, stock movements and hay cutting.

If you would like to learn more about how to use soil moisture probes and the many available on the market as well as how to improve your soil health, book to attend the biggest field day on the Fleurieu on May 15.  

April 19

There is a chance that an intense cut-off low developing off south-west WA will bring some rainfall again for the southern coastal regions, but at this stage it is unknown if it will be enough to constitute a break for the season.

The southern annular mode is likely to continue to remain negative for the next few weeks, meaning more (or stronger) low pressure systems are more likely to develop over southern Australia and this leads to increased storms and rain.

The Bureau of Meteorology POAMA model suggests that wetter than normal conditions are more likely for SA for the two weeks from Anzac Day.

Would you like to present a display or attend our field day on May 15? Book now or contact me at fleurieuforwardfarming.com

• Details: climateandagriculturalsupport.com

April 12

Some rain is likely this weekend across SA with five millimetres to 10mm across the southern coastal regions.

The rain is due to a continued pattern of cyclone development in the pacific causing low pressure troughs, this time with a little rain for SA.

But, this time of year we like to see some frontal rainfall development across SA.

This is not happening, with large high-pressure systems likely to replace the low-pressure trough by Monday blocking any potential frontal rainfall.

Warmer than normal weather and dry conditions will follow.

Frontal rainfall (as opposed to tropical rainfall) for the opening break is becoming less common.

Climate experts are seeing frontal rainfall patterns develop later in the season for SA.

We do seem to worry when we don’t get a break by Anzac Day.  The truth is that only about 20 per cent of opening breaks (of 25mm or more across three days) happen by Anzac Day.

If you would like me to present a workshop for your farm group on local rainfall, weather and climate patterns and what it means for your farming system, contact me melissa.rebbeck@bigpond.com. In the meantime, you can hear from me at our Soil Health and Water Use Field Day on May 15. Book now at fleurieuforwardfarming.com

April 5

Not much rainfall in sight across SA for the coming weeks. Cyclones in the northern area are bringing low pressure troughs without much rainfall for SA.

The strength of the systems associated with cyclones is causing temporary chaos to the normal tracking of SA low pressure systems and frontal system development.

The low-pressure troughs are pushing away the frontal systems that might develop for SA at this time of year. 

You can build resilience to the dry by building your soil health. Latest SA case studies show that the healthier the soil, the more soil moisture it can hold.  You can link to some of the plant available water comparisons at fleurieuforwardfarming.com.

For more information and insights into how to build your soil health and the relationship to PAW come to one of the biggest field days on the Fleurieu on May 15.  Don’t miss your chance to hear the very latest in building soil health and moisture and to peruse the many displays. Book now at fleurieuforwardfarming.com/

March 29

The Bureau of Meteorology surveys international models to gain insight into rainfall and temperature for the coming year.

Most models surveyed by the BoM indicate the tropical Pacific Ocean is likely to remain ENSO-neutral through the southern hemisphere autumn and into winter.

They say that a neutral ENSO pattern does not necessarily indicate average rainfall and temperature for Australia. Rather, it indicates a reduced chance of widespread very wet or very dry weather, and that other climate drivers may have greater influence in the coming months.

These drivers include the Indian Ocean Dipole and the Southern Annular Mode. SAM drives the path of high pressure systems. If they track too low across SA, they block much needed cold fronts from developing.

At the moment, SAM is negative and likely to stay that way for the next three weeks. It means high pressure systems are less likely to block cold fronts. But, it will be dry in SA at Easter and for the next 10 days.  

Details: climateagriculturalsupport.com

March 22

Two tropical cyclones, including Tropical Cyclone Marcus near the WA coast and a developing cyclone above Darwin are giving tropical low push back for southern and eastern Australia.

Tropical Cyclone Marcus is well off the mainland, but the intensity of the low-pressure system – a category 5 cyclone – will cause an extended tropical low across Australia.

This will temporarily push away the blocking high pressure systems dominating and blocking rainfall in southern and eastern Australia and should bring some moisture, cloud cover and rainfall to southern and eastern Australia at the weekend and next week.

But, the rainfall may only reach parts of central SA and the coastal regions and is not likely to exceed 10 millimetres.

How do we make our farming systems more resilient to climate variability and drought? Save May 15 to attend a soil health field day on the Fleurieu, with national speakers, many displays and opportunity for discussion.

March 15

Tropical rainfall influences from Tropical Cyclone Linda will increase humidity across SA late this week and bring some small amounts of rainfall to the coastal regions of SA.

Present blocking high pressure systems may move further south toward the end of the month and bring some more rainfall for southern SA.

The POAMA experimental model suggests southern SA is likely to receive up to 10 millimetres in the last two weeks or March. 

Longer term, La Nina has completely declined, and all indicators suggest a neutral ENSO for the remainder of the year.

March 8

For the past three months, SA rainfall has been about normal in the decile 5 range, while eastern Australian rainfall has had below normal and WA above normal.

March rainfall average totals are typically low for SA with cropping zone average for March ranging from 10-25mm and the coastal fringes receiving 25-50mm (April average totals are very similar).

The Bureau of Meteorology March outlook for SA suggests increased chances of below median rainfall.  But, the POAMA models shows that rainfall may only be below normal by 3mm in March with April rainfall likely to be around 3mm above normal.

Longer term, the ocean and atmosphere models suggest we are headed for an El Nino Southern Oscillation neutral year which typically means rainfall can go either way.

Having a better understanding of when to use outlooks and when to ignore them can support you to maximise profits in good years and minimise losses in bad years.

March 1

The BOM maintains that rainfall is more likely to be below normal for March with the next two weeks receiving around 5mm less than the average. 

Maximum temperatures for the next two weeks will be around normal. 

SA rainfall for Autumn is more likely to be below normal with around 10-30 mm below the 3 month median. Median Autumn rainfall at Buckelboo is 49mm, Adelaide 146mm, Maitland 110mm, Tintinarra 96mm, Kangaroo Island 137mm and Whaylla 52mm. 

SA maximum and minimum temperatures are also more likely to be above the median for Autumn.

Would you like to better integrate climate and weather information into your farm planning?  I can provide a workshop for your farm group or one on one consults.

February 22

The Bureau of Meteorology has released its outlook for autumn, which shows reduced chances of exceeding the median rainfall for SA.

The POAMA experimental rainfall outlook suggests that rainfall is likely to be up to 10 millimetres below normal for most of the state’s locations for each month of autumn.

Maximum temperature is more likely to be above the median for autumn with a 65 per cent to 70pc chance of exceeding the median.

Minimum temperatures are also more likely to exceed the median for April across SA.

February 15

In the past week, sea surface temperatures that normally influence rainfall have returned to normal. The La Nina event has declined and will have little influence on any rainfall around Australia.

For SA, the POAMA experimental model suggests that rainfall will be normal to just below normal for the remainder of Feb and around normal for March.

Daytime temperatures are less likely to exceed the median and night time temperatures are likely to be normal for both February and March across SA.

Details: climateagriculturalsupport.com

February 1

Rainfall is more likely to be about normal for February and March across SA according to the Bureau of Meteorology POAMA experimental outlook.

Daytime temperatures are less likely to exceed the median and night time temperatures are likely to be normal for both February and March across SA.

Outlook accuracy for February is low and somewhat improved for March.  It is understood that the present La Nina has little effect on southern SA rainfall at this time of year.  Furthermore, this weak La Nina event is likely to burn out by autumn according to most climate models.

Details: climateagriculturalsupport.com

January 18

The Bureau of Meteorology has updated its outlook for February.

Past historical accuracy of the BOM outlook in February is low, with the outlook being wrong more than 50 per cent of the time.

It is the nature of this time of year when the ocean and atmospheric conditions are in turmoil and their relationship to follow up rainfall at this time of the year is nonexistent. 

The POAMA experimental outlook showing amounts of rainfall also has low skill at this time of year. It is showing that 6 millimetres to 18mm of rainfall above the median rainfall (at each location) is more likely SA for Feb.

The message of low accuracy is frustrating however outlook model developers are looking for methods to improve forecast accuracy for this time of the year. 

Influencing aspects for more moisture and possible rainfall include warmer than normal sea surface temps in the Pacific and Indian oceans north of Australia.   

January 11

The Bureau of Meteorology has declared a weak La Nina event which is likely to be short-lived.

La Nina events tend to have more impact on increasing the chances of rainfall across northern SA and depending on the strength of the event, tropical moisture can make its way further south.

The BOM outlook suggests increased chances for above normal rainfall across SA for Jan to March, however it is important to understand the likely rainfall amounts.

The POAMA experimental outlook tools suggests that may be some wetter than normal events late this January for the upper north of SA of up to 15 millimetres.  Across the state in February rainfall may be 10mm to 20mm above normal.  For March there are no strong swings toward above or below normal rainfall for SA at this stage.

December 21

The present La Nina influence means that there will be some moisture near Christmas time but only a slight chance of rainfall – about 10 per cent to 20pc – across SA. Furthermore, it is not likely to be too hot across the southern parts of the state in the next two weeks, with temperatures in the mid-20s.

Temperatures will be balmy in the low 30s for the Mid North. But, the Upper North pastoral regions may receive temperatures in the low 40s during the Christmas period. 

For a more precise outlook for your location go to bom.gov.au/australia/meteye

December 14

The Bureau of Meteorology has declared that the tropical Pacific has reached La Niña levels.

Climate models suggest this La Niña will be weak and short-lived, persisting until early southern autumn 2018.

La Niña can bring above average rainfall to eastern Australia during late spring and summer.

However, sea surface temperature patterns in the Indian Ocean and closer to Australia are not typical of a La Niña event, reducing the likelihood of widespread above average summer rainfall across SA.

The BOM outlook shows no strong swings toward above or below normal rainfall for SA for summer.

La Niña can increase the chance of prolonged warm spells for southeast Australia and the BOM suggests warmer than normal daytime and nighttime temperatures are more likely for SA for summer.

November 30

The Bureau of Meteorology says there are three times the normal chance of a La Nina event developing.

If a La Nina declares itself, it is likely to be weak and short lived.

A La Nina increases the likelihood of above normal rainfall for eastern Australia and cyclones for northern Australia. For SA it increases the likelihood of above normal rainfall for the northern parts of the state.

We have a larger chance of receiving rainfall brought by tropical low pressure systems from the north.  Hence when rainfall occurs it is likely to be heavy and run off could be an issue.

Counteracting all of this is the cooler than normal sea surface temperatures in the Indian Ocean.

December is likely to be warmer than normal for SA.

November 23

There are no strong swings toward above or below normal rainfall for December and January across SA according to the Bureau of Meteorology.

There is a 65 per cent to 70pc chance of exceeding the median maximum temperature for December with no strong swings toward above or below normal maximum temperatures for January.

Minimum temperatures also have a greater chance of exceeding the median for December across SA but not January.

Outlook influences are all neutral currently however a La Niña watch remains in place due to recent cooling in the eastern Pacific and warmer than normal temperatures in the western pacific above Australia.  Sea surface temperatures in the Indian Ocean are cooler than normal.

November 16

Warmer than normal sea surface temperatures surrounding Australia and a tropical low are responsible for the widespread rainfall across Australia over the last few days.

A cut of low may bring some smaller rainfall events across the southern parts of SA over the weekend.  Follow up tropical low events are likely over the coming weeks.

Longer term, there is double the normal chance of a La Nina event occurring over summer which enhances the chances of above normal rainfall for the northern parts of SA.

With just two weeks until the summer there are increased chances of above normal daytime temperature across SA.

November 9

It is likely that there will be some rainfall – five millimetres to 10mm – across SA in the last two weeks of November, according the Bureau of Meteorology POAMA model.

Longer term for SA there are no strong swings toward above or below normal rainfall with models suggesting that rainfall is more likely to be about normal for December and January across SA.

In northern Australia warmer than normal sea surface temperatures increase the chances of a La Nina developing, which also enhances the chance of storms and cyclones developing and above normal rainfall.

The warmer than normal sea surface temperatures in summer historically have little effect on SA rainfall.

November 2

The Bureau of Meteorology has released its outlook for November but the accuracy is limited for this time of year across SA.

The outlook shows reduced chances or receiving above normal rainfall for November.

The BoM POAMA rainfall amounts show rainfall is likely to be near or just below average for the month.

There are still warmer than normal sea surface temperatures in the Pacific Ocean along the east coast of Australia and also between Indonesia, Vietnam, and Japan and a La Nina Watch status remains in place. 

For December and January, the BOM outlook currently suggests no strong swings toward above or below normal.

October 26

Warmer than normal sea surface temperatures in the Pacific Ocean along the east coast of Australia and also between Indonesia, Vietnam, and Japan continue to prevail.

The Bureau of Meteorology has announced La Nina watch status with seven of the eight models they survey suggesting a weak La Nina event is very likely for this coming summer.

In SA, a La Nina event can enhance the chances of above normal rainfall in spring and early summer mostly for the northern regions of SA.

But the BoM outlook suggests no strong swings toward above or below normal rainfall across much of SA for November through to January due to counter balancing cooler than normal sea surface temps in the Indian Ocean.

Details: climateagriculturalsupport.com

October 19

Warmer than normal sea surface temperatures along the east coast of Australia and also between Indonesia, Vietnam, and Japan, are fuelling moisture in the atmosphere.

This is bringing large amounts of rainfall to Qld. A tropical low will bring some of that moisture and hence rainfall to southern and eastern Australia late in the week.

NSW and Vic may receive falls of up to 50 millimetres across a few days, but in SA falls of 5-25mm are more likely. It is not unheard of to have similar follow-up events.

For an update on rainfall amounts for your region you can visit the Bureau of Meteorology site.

Details: climateagriculturalsupport.com

October 5

The Bureau of Meteorology’s updated outlook for October suggests that there is a 70 per cent to 90pc chance of exceeding the median rainfall for the Eyre Peninsula and Upper North.

In rainfall amounts, these areas have a 75pc chance of receiving between 10 millimetres to 25mm with the Rangelands region 5-10 mm for October.

While the percentage chance of exceeding the median is lower for the remainder of the state, the Lower North to the South East still have a 75pc chance of receiving between 25-50 mm.

The outlook is influenced by the warmer than normal sea surface temperatures in the Pacific. Rainfall is likely to come from northern tropical low pressure systems.

For more information, visit the Bureau of Meteorology climate outlook site.

Details: climateandagriculturalsupport.com

September 28

The Bureau of Meteorology is not discounting a late developing La Nina event, with the eastern tropical Pacific Ocean temperatures cooling in the past two months and sea surface temperatures in the Pacific surrounding Australia warming.

But, if a La Nina develops in late spring, it will have little to no influence on SA rainfall. 

The Indian Ocean is presently not over supplying moisture and hence rainfall to SA.

At the moment, the rainfall outlook from now until December is for no strong swings toward above or below normal rainfall with a near normal rainfall outlook for most of SA.  

September 21

Ocean and atmosphere indicators for rainfall are bouncing around and hence the Bureau of Meteorology rainfall outlook for October suggests no strong swings toward above or below normal conditions across much of Australia.

Cooler than normal daytime and night-time temperatures are more likely for southern Australia for October.

The POAMA model suggests there may be a small amount of rainfall next week across SA.

For local amounts go to the BoM app or Meteye link.

At the end of next week dry, stable conditions are more likely with an exacerbated chance of frost.

September 14

The POAMA models suggests that normal rainfall is more likely in the next two weeks across SA.

Normal rainfall is also likely for October and November.

This is reflective of the neutral conditions in our oceans and atmosphere surrounding Australia.

Most models suggest these neutral conditions will continue until the end of the year.

Maximum air temperatures are likely to be 1 to 2 degrees Celsius cooler than normal in the next two weeks with minimum air temperatures up to 3 degrees cooler than normal on average across SA.

But, it only takes one very cold night for a frost so be on the watch and act quickly to identify if suspected.  

September 7

After a week of cold, wet weather across southern and eastern Australia, the high pressure systems are likely to move northward and block further frontal rainfall for the next few weeks across SA.

The POAMA model suggests slightly below normal rainfall is more likely across SA for the next two weeks.

POAMA also suggests October rainfall is more likely to be about normal for SA.

Daytime temperatures are likely to be about normal for the next two weeks but night-time temperatures are likely to be cooler than normal so be on the watch for frost and act quickly to identify if suspected.  

Climate & Agricultural Support Pty Ltd has taken reasonable care in this advice. We cannot accept any liability resulting from the interpretation or use of the information set out in this document. 

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