October 2018 New South Wales Climate OutlookThe latest forecast for October from our World Climate Service seasonal climate forecast product indicates that rainfall relief could arrive in New South Wales, Australia, this spring.
The graphic below shows a recent progression of forecasts from a leading climate forecast model. A lot of information is depicted here, so we break it down below.
Left Hand Column - This shows the latest three-week progression of precipitation anomaly forecasts for October from the United States NOAA Climate Forecast System version 2 (CFSv2). The precipitation anomaly forecast is simply the model's expectation of how precipitation will compare to the long-term normal, and is expressed in terms of "percent of normal". The bottom panel indicates a forecast that drier than normal conditions will persist in nearly all of Australia, but the two subsequent forecasts, each a week apart, indicate a progressively wetter forecast for a large area of Australia, including New South Wales.
Right Hand Column - This shows a forecast in probability terms for "below normal", "near normal", and "above normal" precipitation categories. The emergence of the green area in the latest forecast (top right panel) indicates a greater than 40% chance of above-normal precipitation in parts of central and eastern Australia. Note that the probability would be 33% for each category if there was no forecast signal.
Interpretation - A 40% chance of above normal precipitation is not a strong signal and does not mean that the drought in Australia is going to be broken. However, based on the progression of 3 weeks of CFSv2 seasonal forecasts, the trend to a progressively wetter forecast signal suggests that beneficial rain could be coming in October. These forecasts should continue to be monitored to see if the model continues to predict these conditions, and other climate forecast models should also be consulted (available to WCS customers).
On a technical note, the World Climate Service performs a careful calibration of the ensemble climate models to ensure that the probability forecasts are reliable. In particular, the probability forecast depends on the model skill, and therefore it is more valuable than a simple model ensemble average. Probability forecasts are suitable for quantitative decision making and risk management.
The World Climate ServiceThe World Climate Service is a web-based information service designed specifically for commodity trading desks providing:
- Seasonal Climate Forecasts - Forecasts of climate conditions from 1 month to 6 months in advance
- Subseasonal Climate Forecasts - Forecasts of climate and weather conditions from 2 weeks to 6 weeks in advance
- Taking advantage of both dynamical and statistical prediction capabilities
- Emphasizing probabilistic information and quantitative forecast confidence for decision-making
- Creating optimal blends of the information used for prediction
- Providing transparency through on-demand forecast verification and skill statistics
- Predicting and explaining the phenomena and known influences driving the forecast