WILDFIRE: LATEST LEARNINGS- v01.6

WILDFIRE: LATEST LEARNINGS

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General learning outcome:

SPECIFIC FIRE BEHAVIOUR:

Specific learning outcome:

Vorticity-driven Lateral Spread is a major factor in rugged landscapes.

Topic:

The process of Vorticity-driven Lateral Spread, and the setting within which it forms.

Expert Awareness for Fire Behaviour Analysts


Recent research has explained how Vorticity-driven Lateral Spread works. The main conditions are:
  • Rugged landscape, as indicated in the on-line maps on the HFR website. This carries with it a range of interactions between terrain and air flow.
  • A lee-slope aligned to within 40Ý of the reverse of the wind direction – i.e. for a westerly wind (270Ý), an aspect from 50Ý to 130Ý.
  • A lee-slope above 10Ý slope.
  • Ambient winds above 25 km/hr. Under these conditions lee-slope eddy winds dominate.
If a fire enters a site that meets these conditions, then fVorticity-driven Lateral Spread must be considered. Note that there may be other, as yet unidentified, prerequisites.
Should a Vorticity-driven Lateral Spread event be observed or inferred then a Red Flag Warning must be issued.
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This website is dedicated to bringing forward the latest research findings. They are provided to allow firefighters to be made aware of critical safety issues ahead of the material being included in the national training curriculum.
Material prepared by Rick McRae for AFAC Research Dissemination Pilot Study, March 2012.