Seasonal Climate Outlook Message for December 2001 to March 2002
The bottom line
Dated 05/12/01
The monthly value of the Southern Oscillation Index (SOI) has risen from -3.0 at the end of September to +8.9 at the end of November. The Australian rainfall probability outlook for the December to February period is based on the shift in monthly value of the SOI over October/November.
Despite this rise in SOI value a mixed outlook in terms of rainfall probabilities currently exists across Queensland. Regions of the state that have relatively low probabilities (20-40%) of exceeding median rainfall across the next 3 months include a strip running from Broadsound to Townsville shire, parts of the Dalrymple, Flinders and Richmond shires and a large part of north Queensland running from Mareeba to Bourke shires.
A few areas of higher rainfall probabilities exist. These are predominantly in the south west of Queensland where the probability of getting above median rainfall is between 50 to 80%. For most of the rest of Queensland there is currently no strong signal either way as to the next 3 months being excessively wet or dry.
This section will be next updated on the 12/12/01
The full story
Dated 05/12/01
The monthly value of the Southern Oscillation Index (SOI) has risen from -3.0 at the end of September to +8.9 at the end of November. Rainfall probability outlook for the December to February period is based on the shift in monthly value of the SOI over October/November.
Despite this rise in SOI value a mixed outlook in terms of rainfall probabilities currently exists across Queensland. Regions of the state that have relatively low probabilities (20-40%) of exceeding median rainfall across the next 3 months include a strip running from Broadsound to Townsville shire, parts of the Dalrymple, Flinders and Richmond shires and a large part of north Queensland running from Mareeba to Bourke shires.
A few areas of higher rainfall probabilities exist. These are predominantly in the south west of Queensland where the probability of getting above median rainfall is between 50 to 80%. For most of the rest of Queensland there is currently no strong signal either way as to the next 3 months being excessively wet or dry.
For those who like to follow historical patterns more closely years in the past that had a "Rapidly Rising" SOI phase in October/November include 1993, 1984, 1981, 1976, 1973, 1969, 1960, 1959, 1947, 1946, 1934, 1918, 1912 and 1906. What was the rainfall like for the December to February period for those years in your area? Maps of the rainfall in those years can be also be found on this site.
The 30-50 day oscillation is next expected to influence our atmosphere in mid-December. Although strictly speaking it is a tropical phenomenon, it also appears to influence the timing of rainfall events over southern and central parts of Queensland rather than the actual amount of rain.
Most oceanic and atmospheric models continue to reflect ENSO-neutral conditions in the short term. However, there are indications of a slow evolution towards a 'warm' (El Niño like) episode. Since mid 2001 sea surface temperatures have been slowly warming in the central equatorial Pacific ocean. During the same period, subsurface temperatures have also warmed in the same region. This pattern has previously been observed prior to the onset of past 'warm' or El Niño episodes.
Also of interest in the longer term is information that has been sourced from the United States Climate Prediction Centre at www.cpc.ncep.noaa.gov/ During mid-October significant westerly wind bursts were recorded over the western equatorial Pacific ocean. Strong westerly wind bursts in that region have in the past assisted in the development of the necessary pre-conditions required for an El Niño event.
It will be interesting to see to if the warming in the central Pacific reaches El Niño proportions next year and what impact, if any, the recently recorded westerly wind bursts will have.
If anyone requires more climate related information contact the DPI Call Centre on 13 25 23. Alternatively try the DPI's climate web site www.dpi.qld.gov.au/climate on which the "Climate Note" can be found. The climate note contains more detailed information including rainfall probability maps, SST information, world forecasts and detailed regional rainfall probabilities etc. A recorded message with the 30day average of the SOI is also available on 46881439.
This section will next be next updated in the first week of January.
