" Adelaide long range forecast - 12 month rainfall forecast
Other Elders Sites About
There are no warnings current for the Adelaide district.

Adelaide 12-month rainfall forecast

10 5 0
Dec
14

3
Jan
15

6
Feb
15

5
Mar
15

7
Apr
15

4
May
15

3
Jun
15

8
Jul
15

5
Aug
15

5
Sep
15

6
Oct
15

4
Nov
15

9

Rainfall deciles
10 Well above normal
8-9 Above normal
4-7 Near normal
2-3 Below normal
1 Well below normal

Adelaide district forecast
Adelaide 28-day rainfall forecast
Issue Notes

Several features across the tropical Pacific remain close to El Nino thresholds, but collectively, the combined atmosphere and oceanic state has remained ENSO-neutral during the past month. There is greater than a 65% chance of El Nino being declared during this summer, which is expected to last into the autumn 2015. During November, sea surface temperatures (SSTs) continued to increase across the eastern half of the equatorial Pacific, with the Nino-3.4 averaging +1.0C during the month. While equatorial Pacific SSTs have continued to show El Nino conditions, SSTs around Australia have also remained above average. These warm seas around Australia are uncharacteristic during an El Nino and have promoted increased atmospheric moisture levels, contributing to the increased thunderstorm activity during the past month. While the seas of the eastern equatorial Pacific have continued to trend towards El Nino, the atmospheric circulation has yet to show a clear response. The Southern Oscillation Index was only weakly negative during November, with rainfall totals close to average over the eastern tropical Pacific. This lack of a strong response may partly be due to the anomalously warm waters that have persisted in the western Pacific. Based on the current observations and output from global climate models, there remains greater than a 65% chance that El Nino will form during 2014. Assuming that El Nino fully emerges, the model consensus favours a weak event. While El Nino conditions typically lead to drier than normal conditions over large parts of eastern and southern Australia, the anomalously warm seas surrounding the continent are expected to lessen the El Nino impacts for coastal areas. Along the eastern and southern coasts of the nation, models are indicating that rainfall totals will stay closer to or only slightly below the median this summer. It is, however, expected that the eastern and southern interior will see below-to-well-below median rainfall. Moving into autumn, El Nino conditions will continue to influence drier than normal conditions across the eastern and southern interior, however there is no definitive trends in rainfall totals for coastal areas. For south-western parts of Australia, rainfall patterns will also be influenced by warm waters in the southeastern Indian Ocean with near-to-above median rainfall expected during summer and autumn. However, it is worth noting that summer is the driest season of the year for southwest WA. 

Issued 09 Dec 2014

Forecast    Current Conditions    Synoptic Chart    Satellite    Radar   

Forecast Explanation

Notes on the concept of deciles

If all the data in a record are ranked from lowest to highest they can then be divided into 100 equal blocks. These blocks are known as percentiles. The values that fall into the lowest 10% range (from 0 to 10%) are said to be in the first decile, those in the group 10+% to 20% are in the second decile, and so on. Those in the group 90+% to the maximum value recorded are in the 10th decile. The 50% value is a special one known as the 'median'. It is noteworthy since there is the same number of records above and below its value.

Deciles have been found to be very useful for analysing rainfall in particular as its distribution is not the normal bell-shape distribution but is skewed towards many low values with only a few high values. The deciles can be described in qualitative terms. A table is provided in the accompanying results.