Climate update – February 15

Climate update – February 15

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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.

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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