YOUR WEATHER

Using a computer to predict the weather

NASA Satellite Data_clouds over Great Lakes

Satellite image showing clouds over the Great Lakes, USA (c) NASA

How computer models create weather forecasts

It's not enough to merely get weather data, however clever your apparatus for collecting it - have a look at Where do weather forecasts come from? for more information about collecting weather data. To forecast the weather, you need to be able to use the data to predict what's going to happen next in the atmosphere.

Weather forecasts are made by collecting quantitative - numerical - data about the current state of the atmosphere. This data is then put into a mathematical model, which will predict the weather based on current conditions.

In mathematical models, raw data is entered into a computer. A series of calculations is performed on the raw data on it to determine how it will change over time. Normally, mathematical modelling is done by computers, which can carry out many calculations per second.

In the case of weather models, data such as rain fall, temperature and wind speed are fed into a computer. The computer performs calculations on - models - this data, using equations produced from our scientific understanding of atmospheric processes, such as fluid dynamics and thermodynamic equations. These models allow forecasters to predict how the conditions in the atmosphere will evolve. The more sophisticated and up-to-date your model is, the more accurate your forecast should be. Powerful supercomputers are needed to perform the complex calculations in mathematical weather models.

Erin Roberts presenting S4C weather

Erin Roberts presenting S4C weather using 1 kilometre radius forecast model

It's thanks to models that we can process raw weather data into sophisticated and accurate forecasts. The model used to create the unique 1 kilometre radius forecast on Weather Labs is the most sophisticated model available. It is also used for the weather forecasts on the Welsh television channel S4C.

Even the most sophisticated model can't be right all the time. Have a look at Why weather models can get it wrong to find out why.

Weather Data Experiment

weather Schools across the UK can report local weather to help improve forecast
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