Should a Vorticity-driven Lateral Spread event be initiated, the subsequent fire evolution will involve:
- Intense spotting downwind of the flank of the event, for up to 6km, with all spots attaining headfire intensities and rates of spread and rapidly merging.
- A vortex of dense smoke within the lee-slope eddy, with a major, dense, orange-coloured plume emerging from the flank. This is diagnostic.
- The flank of that vortex expanding, laterally with respect to the prevailling wind, at up to 6 km/hr. Note that this takes the spotting zone, above, with it, resulting in fire spreading in two directions at once.
A major expansion of the flaming zone results – it may be some kilometres wide. This creates a convection column that maintains its thermal expansion (and thus prevents mixing with the surrounding air) up to the lifting condensation level. Should this occur, then a violent pyro-convection event will ensue.
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