Very nice report in BBC web today by Jonathan Amos.

MetOp on the launch padOne of the most important European space launches of the year takes place from Baikonur, Kazakhstan, later. A Soyuz rocket will put the four-tonne Metop-B satellite in orbit to acquire critical data for weather forecasters. The spacecraft will ensure there is continuity of observations following on from Metop-A, which was launched in 2006. The computer models that provide our daily forecasts have come to rely heavily on this satellite data.

Full text via BBC