Seasonal Climate Outlook Message for May to August 2003
The bottom line
Climate Watch Dave McRae 06/05/03
The 30day average of the SOI has continued to slowly climb since the start of the month and as of the 7th May was minus 0.3. Based on the recent SOI pattern, a somewhat mixed seasonal outlook exists for May to July across Queensland.
For the gulf, peninsular and a large proportion of the southern half of the state, the chance of getting above the long term May to July median rainfall has remained low at around to 30-40%. Rainfall probabilities across parts of central and western Queensland though are higher at around 50-70% (refer to map).
For example, there is an 40% chance of getting above the long term May to July median rainfall of 100mm at Surat and a 62% chance of getting or getting above the May to July median rainfall of 21mm at Birdsville.
As always when dealing with a probability based forecast system it is important to consider the alternate view. For example, currently there is a 38% chance of getting above 132mm at Esk for May to July. This also means there is a 62% chance of not getting above 132mm.
Another way of looking at this is that in 3 to 4 years out of 10 (or around one third) with the current SOI pattern, Esk has received more than 132mm for May to July. Therefore in 6 to 7 years out of 10 (or around two thirds) with the current SOI pattern, less than 132mm has been recorded at Esk.
The monthly value of the SOI as of the end of April is minus 5.9. Based on the shift in monthly SOI value from the end of March (minus 6.6) to the end of April the SOI is in a "Consistently Near Zero" phase.
For those who like to follow historical patterns more closely, recent years that have had a "Consistently Near Zero" SOI phase at the end of April include 2002, 2001, 1996, 88, 86, 82, 79, 78, 73, 72, 70, 68, 64, 62, 58, 57, 55, and 1953. It can be very useful to find out what rainfall patterns and seasonal conditions where like during May to July in your area for those years.
Much interest is being shown in the next passage of the MJO. As regular readers of this column will be aware, the MJO is simply a band of low atmospheric pressure originating off the east coast of central Africa travelling eastward across the Indian Ocean and northern Australia roughly every 30 to 50 days.
While it is a tropical phenomenon, it appears to indicate the timing of potential rainfall events (but not indicate rainfall amounts) over central and southern Queensland.
If its' timing remains current it will be due next week and is our next best opportunity for some 'climate induced' rainfall.
More information can also be found at www.dpi.qld.gov.au/climate or at www.longpaddock.qld.gov.au
The full story
Climate Watch Dave McRae 06/05/03
SOI Rises Marginally
The 30day average of the SOI has continued to slowly climb since the start of the month and as of the 7th May was minus 0.3. Based on the recent SOI pattern, a somewhat mixed seasonal outlook exists for May to July across Queensland.
For the gulf, peninsular and a large proportion of the southern half of the state, the chance of getting above the long term May to July median rainfall has remained low at around to 30-40%. Rainfall probabilities across parts of central and western Queensland though are higher at around 50-70% (refer to map).
For example, there is an 40% chance of getting above the long term May to July median rainfall of 100mm at Surat and a 62% chance of getting or getting above the May to July median rainfall of 21mm at Birdsville.
As always when dealing with a probability based forecast system it is important to consider the alternate view. For example, currently there is a 38% chance of getting above 132mm at Esk for May to July. This also means there is a 62% chance of not getting above 132mm. Another way of looking at this is that in 3 to 4 years out of 10 (or around one third) with the current SOI pattern, Esk has received more than 132mm for May to July. Therefore in 6 to 7 years out of 10 (or around two thirds) with the current SOI pattern, less than 132mm has been recorded at Esk.
The monthly value of the SOI as of the end of April is minus 5.9. Based on the shift in monthly SOI value from the end of March (minus 6.6) to the end of April the SOI is in a "Consistently Near Zero" phase. For those who like to follow historical patterns more closely, recent years that have had a "Consistently Near Zero" SOI phase at the end of April include 2002, 2001, 1996, 88, 86, 82, 79, 78, 73, 72, 70, 68, 64, 62, 58, 57, 55, and 1953. It can be very useful to find out what rainfall patterns and seasonal conditions where like during May to July in your area for those years.
Much interest is being shown in the next passage of the MJO. As regular readers of this column will be aware, the MJO is simply a band of low atmospheric pressure originating off the east coast of central Africa travelling eastward across the Indian Ocean and northern Australia roughly every 30 to 50 days.
While it is a tropical phenomenon, it appears to indicate the timing of potential rainfall events (but not indicate rainfall amounts) over central and southern Queensland. If its' timing remains current it will be due next week and is our next best opportunity for some 'climate induced' rainfall.
The latest release (dated April 10) from the Climate Prediction Centre www.cpc.ncep.noaa.gov/ in the United States highlights the continuing weakening of the El Nino event during March. Sea surface temperature anomalies decreased by more than 2°C and easterly winds strengthened throughout much of the eastern and central equatorial Pacific.
Some key changes still needed in terms of El Nino breakdown include a return to more positive SOI values as well as a continuing cool down of sea surface temperatures in the central Pacific. This is especially for the region running along the equator east of the International Date Line meet where sea-surface temperatures remain 'stubbornly' warm.
While the risk is low, there still remains a chance that the El Nino will regenerate in some form during autumn/winter this year (especially after the next passage of the MJO). Autumn 1992 is a good example of a partial breakdown in an El Nino pattern with it then reforming in early winter (not necessarily as a classic El Nino but something close to it). Some relief rain followed by a fairly dry winter usually characterizes this type of pattern. These types of years include 1992, 1993, 1994, 1940, 1941, 1912, 1913, 1914, and 1915.
Given current ocean and atmospheric conditions our policy remains not to 'sound the all clear' regarding the complete breakdown of the El Nino system until the end of May.
Whopper Cropper simulations can be used to prepare a number of cropping scenarios for the coming winter season. These scenarios can take into account the changing seasonal outlook, soil moisture levels and different crop types.
What is already known is that a very real advantage for growers is there if they know the amount of available soil moisture. For example on the Darling Downs, wheat and barley median yields can vary from 1.5 tonnes per hectare with a soil moisture profile of one-third to three tonnes per hectare with a soil moisture profile of two-thirds. Therefore knowing the current stored moisture level will allow producers to optimise input levels and potential returns. For more detail on Whopper Cropper contact Howard Cox on 46881381.
As rainfall probabilities and median rainfall levels vary throughout the year and from location to location, we strongly recommend referring to Australian Rainman for more specific rainfall data.
More information can also be found at www.dpi.qld.gov.au/climate or at www.longpaddock.qld.gov.au or ring the DPI Call Centre on 13 25 23 (Qld callers only) or 07 46881459.
