The results of an experiment, which involves verifying a set of quantitative forecasts for Melbourne out to 14 days, are presented. The results are used to assess whether or not extending the period of the official forecasts beyond four days might be justified. The experimental forecasts are verified against ‘climatology’ and a randomly generated set of forecasts. The verification data derived using the methodology suggest that, at present, routinely providing or utilising day-to-day forecasts beyond day 4 would be inappropriate. The data also suggest, however, that it might be possible to provide some useful information about the likely weather up to about six days in advance for some elements, in some seasons and in some situations, for example, maximum temperature during summer. By contrast, in some circumstances it may not be possible to provide useful information even for day 1. Nevertheless, the data indicate that it might be possible to make useful statements about the expected average weather conditions over the 10-day period between days 5 and 14.
Harvey Stern (Wed,) studied this question.