Can a personal weather station increase the weather forecast accuracy?

[Merten]

If it is good enough and can be networked. In a sense, it started with ships and buoys sending local information to a central gathering point for analysis and broadcast. Personally, I think it is much more accurate and more reliable than modern computer models.

[Michel Rikonen]

The Met Office system allows automatic weather station data to be sent to a web portal. In the future, these data may be useful to complement the network of high quality stations they serve and other National Meteorological Services.
If your data turns out to be of good enough quality, it can potentially be used in their weather forecasting models to improve forecasts.