6. In Max Time Step, specify the maximum time that the Forecast product looks back to
find the previous image.
The FCAST product calculates the mean echo motion by doing a correlation between
the current and previous image.
The example value of 15 minutes is a reasonable starting point since the average life of
an individual convective cell is approximately 30 minutes.
7. In Output Resolution, specify the resolution of the output field of vectors.
FCAST products produces a single motion vector. You can also make your own forecast
product using your own algorithms. These can have a field of non-uniform motion
vectors.
The total size of the output field matches the size of the input product (in km). For
example, if the input product has a 200 km (124.3 mi) range (400 km (248.5 mi) total
span), and the output resolution is 5 km (3.1 mi), then the output is a grid of 80 × 80
motion vectors.
8. To display and use the FCAST product in forecasting to, select Quick Look Window >
Forecast
The display of the forecast product shows an array of motion vectors similar to the
WIND or NDOP products.
The Quick Look Window displays support additional features that are not supported by
the FCAST product itself:
• Non-uniform motion fields are correctly used in the forecast.
• Non-uniform intensity changes are correctly applied.
The forecast product creates a corresponding array of intensity changes which are
all set to 1.
More information
‣
Forecast Tool (page 241)
‣
WIND and FCAST Output Options (page 257)
Chapter 3 – Configuring IRIS Products
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