FAIR WEATHER FORECAST
SIR,—In last week's number you spoke of the Met- eorological Office's forecast for December as 'cagey' because it contains 'only eighty words, and only the last five of them, "but little snow is expected," could possibly be wrong.' Actually, the words com- plained of contain the following definite predictions: (i) that the wet weather that characterised November will not continue and that the total rainfall for the month will be below average in the south-east and near average elsewhere; (ii) that the mean temperature for the month will be below average in England and Wales and about average in Scotland; (iii) that there will be some severe cold spells with freezing fog at times and (iv) that there will be little snow. None of these statements is bound to be correct, for they imply a rather chilly dry December instead of, say, a mild wet month or a bitterly cold snowy one. As explained in the leaflet that accompanies the forecast, the word 'average' here means the climatic or long-term average, covering roughly the last thirty years.
I think that 1 should add that it is understood by all concerned in the preparation of these monthly forecasts that the phrases in the 'prospect' must be such that they can be checked for accuracy after the event. Without such restriction it would be impossible for us to evaluate the reliability of the system now in we.
Meteorological Office, Bracknell, Berkshire
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