# Gathering data for a weather forecast

## Where to find information for weather forecasting

These activities will help you understand where to gather weather information and to understand some basic types of data used in forecasting.

When preparing a weather bulletin, students will need to think about where to find the data they need.

There are lots of websites with information about the weather including BBC Weather.

The Met Office have weather data in their Teacher Resources which students can use to create their own forecasts.

The Royal Meteorological Society have resources for teaching weather on their MetLink site.

If your school has its own weather station, you could use the data collected to prepare your own forecast, which will be specific for your own area.

You could work with Geography and Computing specialists to create your own weather data.

## Observed and forecast data

Get students to watch this video with Chris Fawkes and ask them what the difference is between observed and forecast data. Ask students to make an educated guess and then explain.

When we observe something we watch what it does. Therefore, observed data is something which has happened or is happening now. For example, a satellite picture is a photograph taken from space. This is weather that has happened, and is factually accurate.

To forecast is to predict, so forecast data is what we believe will happen in the future. For example, it is possible to forecast where rain will fall. This may not be exactly right, as nature is unpredictable, but scientifically we can forecast what we think will happen.

Ask students to think of other situations where observed and forecast data are used.

For example, you can observe a particular football team has the best players and forecast they may win the Premier League. But during the season you might observe a spell of defeats, which makes the forecast of winning the title less likely.

Therefore, the more you observe, the more you can contribute to a forecast.

Ask students why they would want to show an audience both observed and forecast information.

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## Model (or grid) data

Visit BBC Weather and type your area name or postcode in the search box. Beneath the five-day forecast is a map showing the weather where you are.

Explain to students that the information on the map is called model (or grid) data. This is because it is created by dividing the forecast area into a grid of squares and giving each square the relevant type of weather for that time of day. You cannot see the squares on the website.

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## Timeframes

At the same time as being split into geographical squares, model products are also split into timeframes.

Get the students to look at the weather map again.

Click the play icon at the bottom of the map, and watch the weather change over the next few days.

Ask students: What length are the time frames? (for example, every three hours and 12 hours.)

Do they notice the jumpiness when moving between the timeframes?

Explain to students, when you watch a smooth broadcast on the TV, the movement is created by the BBC graphics system interpolating between data points. So the computer is giving the best guess possible of what the weather is doing between the time steps.

The result of using model or grid data is a set of graphics which show where the weather currently is, and how it is going to develop. It helps the audience see a visualisation of the weather on the map.