HC Deb 01 May 1968 vol 763 cc1109-11
57. Mr. Gresham Cooke

asked the Secretary of State for Defence why the weather forecasts for South-East England on 22nd April when warm and dry was forecast, on 25th April when two further fine days were forecast and on 27th April when rain was forecast to clear by the evening were incorrect; and whether such forecasts are now made by computer or the human mind.

Mr. Merlyn Rees

Scattered thunderstorms in South-East England were forecast for 22nd April on the previous day, but a trough of low pressure moved faster than expected to produce more widespread outbreaks of rain. The forecast was modified from the early hours of 22nd April onwards, when the day's weather was correctly forecast. On 27th April rain spread more rapidly from the west than had been expected when the outlook was given two days previously.

The accuracy of forecasts, particularly in the timing of events, inevitably decreases as the period covered is lengthened. The forecast for South-East England for 27th April, as given on 26th and 27th, was correct. Clearance of rain was forecast for other areas but not the South-East. The weather is forecast by human forecasters, who take account of forecast pressure charts produced by the computer.

Mr. Gresham Cooke

Does this mean that the Government have finally fallen into the trough of low pressure?

Mr. Rees

Not at all. I suggest that prediction in meteorology is as suspect as prediction in election results.

Mr. Shinwell

When are the Government going to do something about this? When my hon. Friend refers to human forecasters, does that mean that there are no human beings in the Government capable of dealing with this matter?

Mr. Rees

I think it has something to do with 13 years of Tory rule.

Mr. Lubbock

Is the hon. Gentleman aware that if one takes the precise opposite of the forecasts given, one finds that, as with other forecasts made by the Government, one's predictions can be reasonably reliable?

Mr. Rees

As with Liberal Party policy.

Mr. Maudling

Will the Minister call to the attention of his colleagues in the Economic Departments his remarks about the fallability of human predictions, particularly in relation to the National Plan?

Mr. Rees

I am sure that the right hon. Gentleman has great experience of that.

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