WILDFIRE: LATEST LEARNINGS- v01.6

WILDFIRE: LATEST LEARNINGS

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General learning outcome:

SPECIFIC HIGH COUNTRY WEATHER:

Specific learning outcome:

When prevailing winds exceed 25km/hr lee-eddy winds may become important.

Topic:

The implications of the dominance of lee-slope eddies for fire behaviour.

Expert Awareness for Fire Behaviour Analysts


As, in general terms, intense fire runs are the most likely to produce spotting, both the windward and leeward runs may produce spot fires for some distance downwind that reflects the fire danger index. As a rule of thumb, the spotting distance is less than 2 hours level ground forward spread. Lofted embers flow with the prevailing wind. Thus if conditions are severe enough for the windward run to produce medium range spotfires, these may occur near the bottom of the lee-slope eddy, and thus produce a major uphill run on the leeward side, which is equally able to spot onto adjacent landform elements. This leapfrog-style fire spread negates control lines and jeopardises fire crew safety.
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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.