Bureau of Meteorology Australian Digital Forecast Database Grid (ADFD). Forecasts are issued by the Bureau of Meteorology on a routine basis for each state and merged into one forecast grid for Australia for each forecast element.
This forecast element (hazardous wind onset) shows if and when hazardous winds will arrive over the next six hours. 'Hazardous' wind is defined as average wind speed 26 knots and above or wind gusts 42 knots and above—a threshold chosen for the safety of recreational boaters. When used in conjunction with official warnings and forecasts, this can provide emergency managers and safety organisations with greater awareness about the onset of dangerous conditions.
Hazardous wind onset is produced using two ADFD grids—hourly wind and wind gust forecasts. The output is a single grid with four modes, showing winds that are:
0 = currently forecast to be hazardous
1 = expected to be hazardous in the next two hours
2 = expected to be hazardous in two to six hours
3 = not expected to be hazardous in next 6 hours
Unlike other ADFD grids, this grid is updated hourly and contains no time dimension.