Wednesday, 20 October 2010

BBC weather

I keep a close eye on the weather forecast when I go walking. The handiest of these is on the BBC website, although I have found that their web-based system is, frankly, odd. It seems to change randomly, and also bears little relevance to the broadcast weather updates (or, indeed, the actual weather when it happens).

I have considered writing a utility to automatically grab the BBC weather forecast every six hours, logging the changes and comparing with the Met Office's record of what really happened with the weather. This has remained low down on my to-do list.

Today, however, I got firm evidence with none of the hassle.

Last night, before I went to bed, the summary forecast (with home area set to Romsey) showed sunshine for the next three days. This morning, the summary showed heavy rain, as seen below. All images were made within a period of five minutes shortly after 08.00 this morning.

The forecast for heavy rain was strange, as a glance outside the window showed a cloudless sky and the first ground frost of the year. Of course, it may rain later, so I drilled down further to look at today's weather in detail:

Note, bright sunshine and no sign of the heavy rain. The location is still set as Romsey. And Thursday's details:

Finally, on Thursday evening, we get a light rain shower (not the 'heavy rain' forecast). So the summary predicts heavy rain for the next two days, but the details show bright sunshine. Obviously these both cannot be correct. The questions is, how can we rely on the weather forecast when it is not even internally consistent?

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