- WEATHER
Australia
- National
- New South Wales
- Victoria
- Queensland
- Western Australia
- South Australia
- Tasmania
- ACT
- Northern Territory
Long Range Forecasts
- WARNINGS
- RADAR
- SATELLITE
- MAPS & CHARTS
- LONG RANGE
Long Range Forecasts
- CLIMATE
Climate Indicators
- NEWS
Mid North 12-month Rainfall Forecast
10
5
0
| Rainfall deciles | |
|---|---|
| 10 | Well above normal |
| 8-9 | Above normal |
| 4-7 | Near normal |
| 2-3 | Below normal |
| 1 | Well below normal |
Issue Notes
ENSO status: La Niņa Watch.
IOD status: Neutral.
SAM status: Positive. Trending positive.
The El Niņo Southern Oscillation (ENSO) is in a La Niņa Watch, meaning there is approximately a 50% chance of a La Niņa developing this year. The current technical definition of a La Niņa is only a small chance to be met, although ocean and atmospheric conditions do resemble a La Niņa pattern. Trade winds are still stronger than average along the western equatorial Pacific, and the Nino3.4 is low, but is above the threshold of -0.8C. However, the Relative-Nino Index (factors in equatorial ocean temperatures elsewhere around the world, compensating for the background warming signal) is below the threshold. A La Niņa typically increases rainfall over northern and eastern Australia (especially eastern Qld) during summer, but has little effect for WA and SA.
The Indian Ocean Dipole (IOD) is in a neutral phase. Recent conditions have been similar to a negative IOD, but this has likely been heavily affected by very active bursts of tropical weather in mid-October and mid-late November. Regardless if these conditions continue, the arrival of the monsoon over northern Australia overwrites any IOD effects, so this driver is unlikely to significantly affect Australia this year.
The Southern Annular Mode (SAM) is in a positive phase, having switched from the negative phase that persisted from July to October. This positive event is expected to persist through summer as a result of stratospheric moisture from the 2022 Tongan volcanic eruption (similar to the past two summers). A positive SAM decreases the frequency of cold fronts, with more regular high pressure systems and easterly winds. During summer, this increases rainfall over eastern Australia, and reduces rainfall over southeastern SA, western Vic and western Tas.
Rainfall outlooks are showing above average rainfall over western, northern and eastern Australia, with strong signals over the Kimberley, Top End and Cape York Peninsula (likely related to forecast monsoon activity). Drier conditions are expected for western Tas, with average conditions for SA and western Vic.
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.
Enter a postcode or town name for local weather, or text to search the site. » advanced search
Adelaide Test forecast: Showery first day, then fine
17:22 AEDT Dark clouds are looming over the Australian batting order at present, but after a potentially showery first day, the weather should clear up for the last four days of the second men's day-night cricket Test between Australia and India at the Adelaide Oval starting this Friday, December 6.
Help with Farmonline Weather
