The Met Office has been attacked for its seasonal forecast this winter. John Hirst, its chief executive, admitted that “our recent seasonal forecasts have been disappointing” (Comment, Jan 15).
But this is not the whole story. In November the forecasters had warned there were signs of cold weather this winter, adding that the chances of this cold weather were twice as likely as in recent winters. The crucial word was “chances”, because seasonal forecasts give a probability, not a certainty, of what is going to happen in the months ahead. However, we have got so used to accurate daily forecasts about conditions the following day that we are not used to dealing with probabilities in weather forecasting. Yet we deal with probabilities in so many other things in life — the chances of winning the National Lottery, of being hit by lightning, of living to a ripe old age, and so on.
The fiasco of last year’s forecast of a “barbecue summer” is a good example. The seasonal forecast said there was a high chance of above-average temperatures during the summer, which proved to be correct. The forecasters also explained that they had no clear indication of what the rainfall would be. It was the summer rains that ruined the barbecues, not the temperatures. Seasonal forecasting is exciting, cutting-edge science, but it is far from foolproof and needs to be used with caution.
The Met Office is asking the public about using probabilities in forecasting at: http://bit.ly/6Tuynb