Weather forecasting used to be much more accurate, as shown by its part in planning WW2 Operations. Older members will recall that it used to be quite reliable . It's still possible to get accurate forecasts privately but you have to pay for them, which many big industries and farming concerns do.
Unfortunately you have to use proper physics and meteorology to do that rather than "computer modelling ". Thing is though, that such actual science quickly rules out the idea of man made climate change, which is not a conclusion which can be allowed.

If we intend to perpetuate the idea of man made climate change with all the benefits that brings to rich people such as revenue, reduction of competition and a reason to legislate against freedoms, then we must use the politically defined version of science rather than the old version which relied on fact rather than commerce and control.

Therefore the BBC , like all State funded institutions must use "computer modelling" and other methods which are designed to corroborate the claims and predictions of the State and we therefore cannot expect results which are entirely compatible with scientific reality.

Science, like literature and history is now the province of the State and its dumbed down "education" system rather than those who study these disciplines objectively. This isn't new - it's happened in both Germany and the Soviet Union in the past , and it's doomed to eventual failure in the same way. However, since we appear to be content for the moment to put up with it, I'm afraid that we can't expect accurate weather forecasting any more than we can expect truthful history or the exemption of literature from censorship.