Page History

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Output focuses mainly on the week-to-week changes in the weather rather than attempting to give unsupportable detail on individual days.  Output is mostly in the form of anomalies relative to ER-M-climate and is mainly shown as 7-day means for calendar weeks Monday-Sunday.   Specialised products for the extended range also include information on potential tropical cyclone activity and the Madden-Julian Oscillation (MJO) during the coming month.

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Graphical Products

For each point of the chart the atmospheric variables (e.g. 2m temperature, surface temperature, total precipitation, mean sea level pressure) have been averaged over week-long periods.  Extended range 7-day mean forecast chart products to day46.  

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Significance and confidence

Significance

The " anomaly", as shown on some of the extended range ensemble products, is the difference between the ensemble weekly mean of the real-time forecast and the corresponding ensemble weekly mean of the ER-M-climate.  On web charts, the regions where the significance of this anomaly (difference) is:

• greater than 99% are delimited by a dashed contour (blue: wetter, colder or lower pressure; red: drier, warmer or higher pressure).
• greater than 90% are coloured (blue: wetter, colder or lower pressure; red: drier, warmer or higher pressure).
• less than 90% are left blank (taken as not significantly different from ER-M-climate) are left blank.

Confidence

On extended range web charts the confidence is "over-stated", because reliability diagrams consistently show that forecasts are over-confident.  Thus where a high probability of a particular type of event is predicted, the "true" chances of that event happening are actually less than the probability that is shown. 

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