The key principle behind an appropriate wildfire prediction system is that fire behaviour within any given fuel is influenced predominantly by three major forces:
- Wind
- Slope
- Aspect
These three factors are referred to as the ‘forces of alignment’, because whenever a wildfire is supported by either the wind, slope and/or aspect it will burn with greater intensity and spread more rapidly. If the fire loses the support of the wind, slope and/or aspect the intensity and rate of spread will decrease. An understanding of how these three factors, along with the type, condition and continuity of the fuel, influence fire behaviour and firespread is of vital importance for developing safe and effective tactical plans for wildfires. More specifically, this understanding is necessary for:
- Identifying windows of opportunity
- Identifying critical points
- Selecting appropriate trigger points
- Selecting appropriate suppression tactics for use at particular times and places refer to control measure ‘Consider appropriate fire suppression tactics and develop and implement a tactical plan‘
- Implementing the LACES safety protocol
It should be understood that sometimes the parts of the fire that show little activity (for example, lower intensity parts of the fire with lower rates of firespread) may actually have the most potential for future fire development. Tactical plans for wildfires should be based on what it is likely to happen in the future, and the initial and continuing priority must be to analyse the fire perimeter and establish what potential each part of the fire has for changes in intensity and firespread.
Refer to the section on ‘The wildfire prediction system’ in the Scottish Government’s Wildfire Operational Guidance for further information about predicting fire behaviour.