Forecasts from the Met Office begin by taking observations from around the world, which come from observations on the land and at sea, weather balloons and commercial shipping and aircraft. Perhaps the most important source for weather predictions is the uninterrupted supply of data that comes from satellites.
Observations from space have helped to revolutionise how weather forecasts are produced. All this data pours into the supercomputer at the Met Office headquarters, where global predictions are made every six hours. The supercomputer uses the observational data and then calculates billions of equations every second, as to how the atmosphere may change over the coming days in the form of charts and graphics.
Once the unmodified forecast is produced, the Met Office chief forecaster then assesses the various graphics where modifications will be made as and where is necessary. Once the chief forecaster and his deputy have finalised the forecast, guidance is produced that provides specific details for the next five days and in broader terms out to day 30. The guidance is used on the Met Office website and is used by broadcast meteorologists for the UK media, including the BBC and ITV.
Answered by the Met Office