Intent

Create both awareness and conversation among fire personnel around a relatively unknown fire behavior phenomenon called the Counter Rotating Vortex Pair (CRVP). Concisely describe conditions that may lead to CRVP formation for tactical resources like crew lookouts and Division Supervisors (DIVS).

Facilitator Preparation

• Review the video and module tools.
• Consider additional activities and discussion questions pertinent to the location and agency.
• Familiarize with discussion questions and concepts:
• Consider what a posted lookout could recognize in terms of weather, topography, fire location, and fire behavior that could lead to CRVP formation.
  • Is the fire located on the lee side of a ridge or mountain range?
    • How would a lookout notice wind shear at ridgetop level?
    • What other terrain features that alter general wind flow can you observe?
      • Ridgetops compress airflow, drainages and canyons funnel airflow.
  • Is there a large column from an area ignition or deep flaming zone?
    • A column impedes wind flow and air must flow around it, which can create vorticity (rock in the river analogy).
    • Is the column splitting into two?
    • Are the columns starting to rotate?
• Given the information in the video, what are other considerations you may think about specific to lookouts in the future?
  • Examples might be physical location, field of view limitations, and/or time of day.
• Describe ways resources can work together on a fire to interpret and communicate the fire behavior if the conditions for CRVP formation are present.
  • Examples could be strategically, from the Fire Behavior Analyst (FBAN) to DIVS.
  • Or tactically, between crews and their lookouts on a division.
• Why are Counter Rotating Vortex Pairs dangerous to fireline personnel?
  • Can create locally strong, unpredicted surface winds that exponentially increase spotting potential on the flanks, where firefighters commonly work.
  • Can result in erratic fire behavior and irregular fire spread patterns.

Facilitating the Discussion

• Show the video.
• Facilitate a group discussion using the discussion questions.

Questions / Scenario / Directions

1. Consider what a posted lookout could recognize in terms of weather, topography, fire location, and fire behavior that could lead to Counter Rotating Vortex Pair formation.
   1. Is the fire located on the lee side of a ridge or mountain range?
      1. How would a lookout notice wind shear at ridgetop level?
      2. What other terrain features that alter general wind flow can you observe?
         1. Ridgetops compress airflow, drainages and canyons funnel airflow.
   2. Is there a large column from an area ignition or deep flaming zone?
      1. A column impedes wind flow and air must flow around it, which can create vorticity (rock in the river analogy from video at 6:27).
      2. Is the column splitting into two or does it appear to be “kidney shaped?”
      3. Are the columns starting to rotate?
2. Given the information in the video, what are other considerations you may think about specific to lookouts in the future? Examples might be physical location, field of view limitations, and/or time of day.
3. Describe ways resources can work together on a fire to interpret and communicate the fire behavior if the conditions for CRVP formation are present.
   1. Examples could be strategically, from the FBAN to DIVS.
   2. Or tactically, between crews and their lookouts on a division.
4. Why are Counter Rotating Vortex Pairs dangerous to fireline personnel?
   1. Can create locally strong, unpredicted surface winds that exponentially increase spotting potential on the flanks, where firefighters commonly work.
   2. Can result in erratic fire behavior and irregular fire spread patterns.

Resources

• Website: El Dorado Fire StoryMap
• Document: El Dorado Incident - Learning Review Narrative
• Document: El Dorado Incident - Organizational Learning Report
• Document: Review of Vortices in Wildland Fire
• Document: Large-scale fire whirl and forest fire disasters: Awareness, implications, and the need for developing preventative methods

Additional Video Information

• This video is also available as a download (zip file, size 1.2GB) with the .srt file for closed captioning (you may need to right click and Save As). For information on how to add closed captioning to a video, see this how to page.
• Note: For Chrome and Firefox, right click the word download and select Save Link As; for IE, right click and select Save Target As.