Fire BlowUp Modeling: Implications for Situational Awareness

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Fire Blow-Up ModelingImplications for
Situational Awareness LCES

• Jo Ann Fites
• Adaptive Management Services Enterprise Team,
  USDA Forest Service

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Overview

• Importance of fire accelerations in fatality
  fires
• Near misses?
• Modeling canyon blow-ups
• Test on Rattlesnake fatality fire
• What does this mean for situational awareness
  LCES?

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Fire Fatalities Blow ups
What is common to loop, rattlesnake, south
canyon, Cramer and others?

• Numerous fire fatalities from blow-ups
• Especially in drainages or canyons or chimneys
• Easily recognized but how fast can blow-ups
  occur?
• Does the speed sink in?

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Modeling Canyon Blow-Ups

• Holding your finger near a match
• Viegas canyon blow-up model
• Based on laboratory tests
• Mathematical landscape application
• Tested with rx burn in chaparral
• Viegas applied to several fatality fires in US
• Future predicting when blow-ups occur?

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Rattlesnake Fire - Test

• 1953 on Mendocino National Forest
• 15 fatalities
• Acceleration in small drainage a key factor
• Sundowner winds a factor
• Applied Viegas model

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Viegas model simulation
2 versions tested 1 simple 2 canyon angles
Assumptions winds 3m/s, alpha.000045
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Follow the leader or model?

• Model is useful but cannot substitute for the
  computer with slides in their head
• (if it will blow-up)

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Applications

• What are the implications?
• LCES
• How much time do you have
• for egress?
• What are your triggers?
• Chuck Hartley
• when fire hits the bottom it is time to
• go..not wait and see what happens
• But this depends on the situation

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Codfish fire
structures
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• Egress times for crews from bottom of canyon vs
  potential speed of fire up chimneys?
• 45 min. out for hotshot crews
• Accel. times of 13 to 50 minutes

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Sz?
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Operations

• 1) Where might it escape, size of WFSA
• -does the box need to be bigger?
• 2) overall hazard awareness for resources
• - improve situational awareness
• - not a substitute but some means of a slide
  for inexperienced crews
• 3) egress
• - info to compare egress time estimates
• - setting triggers go when it is at the bottom
  no matter what the size of fire
• 4) spacing of safety zones
• Have to rely 1st upon good, experienced
  leadership what is going on at the fire
  (Codfish Rax I told you it would not reach
  your sensors
• --this tool is supplemental

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