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Interpreting Data

What is Opticast?

What is Opticast?

Opticast is an automated forecasting system designed to produce detailed forecasts for specific times of each day. The system works by taking forecasts from a range of computer models and comparing them with past observations to produce the most accurate possible forecast possible, tailored to a specific location where weather observations are taken.

What does Opticast allow me to do?

Opticast allows you to 'drill-down' into the daily forecast, giving you a more exact idea of your local conditions at particular times of interest to you. For example, if you cycle to work you are likely to be most interested in the temperature, wind and chance of rain at 6am and 9pm. Or if you're organising an afternoon party and the daily forecast is for late thunder, you'll want to know what time the bad weather is likely to arrive.

Why is the Opticast forecast different to the daily forecast?

The daily forecast gives a general summary of the day's weather over a small region, and is typically produced by human meteorologists based on raw computer models and personal experience. Opticast gives a forecast for a specific time and location, and comes from an optimisation of computer model output with actual observations. These differences in approach mean that at times there will be differences between the two forecasts.

What does the Opticast rain probability represent, and how is it different to the daily rain probability forecasts?

Whilst Weatherzone's 7 day rainfall probability forecasts are for the chance of measurable rain occurring in the 24 hours from 9am, the Opticast rainfall probability forecasts are for the chance of measurable rain occurring during a one-hour period centred upon the time the forecast is for.

How accurate is Opticast?

Opticast is among the most accurate automated forecast systems available. Typical average errors for temperature are 1-2 degrees, for relative humidity 5-10 percent, and for wind 5-10 km/h. The errors are generally less than half the errors found in raw computer model forecasts. This impressive error performance is a result of the unique optimisation techniques employed by Opticast.

What times is Opticast available for, and how far into the future does it go?

Opticast is available on Weatherzone at 3-hourly intervals, extending 48 hours into the future to cover today and tomorrow.

How often does Opticast update?

Opticast is updated on Weatherzone approximately every six hours.

What other uses does Opticast have?

Opticast has significant applications in a range of industries including Energy, Mining, Construction, Marine and Agriculture. For these applications the data can be available down to half-hourly intervals extending out to seven days ahead. To find out more about how Opticast can work for you, visit our Opticast product page at

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