Seasonal Climate Outlook Message for February to May 2004
The bottom line
Climate Watch Dave McRae 3rd February
As we predicted last month the MJO (40 day wave) is now having an impact on our weather. It will be interesting to see what influence the current MJO has, as it is 'carrying' a large amount of atmospheric moisture. Research has also shown that in summer the MJO can intensify the monsoon season as well as help trigger cyclones if there are any existing low-pressure systems in the Coral Sea.
There is also the potential for it to create westerly wind bursts in the central Pacific after it has passed over Australia. Regular followers of this column would be aware that at this time of year (through to late autumn) westerly wind bursts in the Pacific can help trigger an El Nino event.
The last passage of the MJO influenced our weather in late December. It helped produce some useful but patchy rainfall mainly across eastern Qld (with much of south west and central Qld missing out).
Despite the fall in the value of the SOI from the end of December (plus 9) to the end of January (minus 12.8), some areas of the state (eg parts of the Warrego, western Darling Downs and Burnett) have a reasonable 50-70% chance of getting above the long term February to April median rainfall. For example, Talwood has a 68% chance of getting above its long term Feb to April median rainfall of 160mm.
However, for parts of the far south west, central west and central north, the chance of getting above the long term February to April median rainfall has fallen to 20-40%.
For the rest of the state there is no strong signal towards either wetter or drier than normal conditions with a 50/50 chance of receiving above median rainfall. The latest rainfall probability maps can be found at www.dpi.qld.gov.au/climate or www.longpaddock.qld.gov.au
The 30day average of the SOI has risen since the start of the month an as of the 4th February is minus 8.7. Daily updates on the SOI are available on 46881439.
As probabilities and median rainfall levels vary, we recommend referring to AUSTRALIAN RAINMAN for more specific rainfall data for your location. Or you can contact us through the DPI Call Centre on 13 25 23.
The full story
Climate Watch Dave McRae 3rd February
Welcome Rain for Queensland
As we predicted last month the MJO (40 day wave) is now having an impact on our weather. It will be interesting to see what influence the current MJO has, as it is 'carrying' a large amount of atmospheric moisture. Research has also shown that in summer the MJO can intensify the monsoon season as well as help trigger cyclones if there are any existing low-pressure systems in the Coral Sea.
There is also the potential for it to create westerly wind bursts in the central Pacific after it has passed over Australia. Regular followers of this column would be aware that at this time of year (through to late autumn) westerly wind bursts in the Pacific can help trigger an El Nino event.
The last passage of the MJO influenced our weather in late December. It helped produce some useful but patchy rainfall mainly across eastern Qld (with much of south west and central Qld missing out).
Despite the fall in the value of the SOI from the end of December (plus 9) to the end of January (minus 12.8), some areas of the state (eg parts of the Warrego, western Darling Downs and Burnett) have a reasonable 50-70% chance of getting above the long term February to April median rainfall. For example, Talwood has a 68% chance of getting above its long term Feb to April median rainfall of 160mm.
However, for parts of the far south west, central west and central north, the chance of getting above the long term February to April median rainfall has fallen to 20-40%.
For the rest of the state there is no strong signal towards either wetter or drier than normal conditions with a 50/50 chance of receiving above median rainfall.
When using probabilities or a percentage chance of something occurring (eg amounts of rain in a 3 months or winning the lotto), it is important to consider the opposing view. For example, while Chinchilla has close to a 70% chance of getting above its long term February to April median rainfall of 182mm this also means that there is close to a 30% chance of not getting above 182mm.
Another way of looking at this is that in approximately 7 years out of 10 (or around two thirds of years) with the current SOI pattern, Chinchilla has received more than 182mm for February to April. Therefore in around 3 years out of 10 (or one third), Chinchilla has gotten less than 182mm for this period.
Rainfall probabilities especially when compared with the January to March seasonal outlook have improved across much of NSW, Victoria and the southern half of South Australia to a 60-80% chance of getting above the long term February to April median rainfall.
Lower rainfall probabilities (30-50%) can be found in the Northern territory and much of Western Australia. For the rest of Australia there is a 50/50 chance of receiving above median rainfall.
The latest rainfall probability maps can be found at www.dpi.qld.gov.au/climate or www.longpaddock.qld.gov.au As rainfall probabilities and median rainfall levels vary across the state, we recommend referring to AUSTRALIAN RAINMAN for more specific rainfall data for your location. Or you can contact us through the DPI Call Centre on 13 25 23.
Many people like to follow the historical SOI/rainfall patterns in more detail for their locations. For those interested, discovering what rainfall and farming conditions where like in your area for February to April in 1998, 1971, 1970, 1969, 1961, 1958, 1955, 1946, 1933 and 1928 could be useful.
At present both the United States Climate Prediction Centre www.cpc.ncep.noaa.gov/ and the Australian Bureau of Meteorology www.bom.gov.au/ state that at present a neutral SST pattern can be found in the tropical Pacific Ocean. However, some re-warming of SST in the central Pacific and the potential return of westerly wind bursts to this region (especially after the current passage of the MJO) have increased the risk of 'El Nino-like' conditions to develop this coming winter.
Ocean and coupled ocean/atmosphere forecast models can show likely SST development out to 9 months. Of 11 models that forecast out to June, 6 indicate the continuation of a neutral SST pattern while 5 suggest the potential development of an El Nino (or warm) SST pattern.
Of the 9 models that forecast out to September, 7 indicate a continuing neutral sea temperature pattern while 2 suggest the potential development of an El Nino pattern.
While it is positive that around half of these models highlight a continuing neutral SST pattern (rather than an El Nino), given current conditions our policy remains to recommend caution when considering the longer term outlook. It's also worth remembering that at this time of year most models fall away in their forecasting capability for a few months as we enter the autumn period. So unless there is a very strong event coming as in 1997 (but which had little effect here on rainfall) then some models do not tend to show an El Nino event until mid winter, by which time it is too late for us.
Therefore it could be useful for businesses that are adversely affected by these events to consider now what risk management strategies they could use if the likelihood of an El Nino event increases.
More details can be found at www.bom.gov.au/climate/ahead/ENSO-summary.shtml
