Extensive Wildland Fire Weather Research of the Tragic June 2013 Yarnell Hill Fire

On June 30, 2013, the epic Arizona State Forestry (ASF) managed Yarnell Hill Fire in Central Arizona resulted in 19 Prescott Fire Department (PFD) Granite Mountain Hot Shots (GMHS) being killed in one fell swoop, with wildland fire weather definitely a causal factor. Two investigations ensued, one a Serious Accident Investigation (SAIT) and an Arizona Occupational Safety and health investigation (ADOSH) and their respective reports a SAI Report (SAIR) and the ADOSH (GMHS Entrapment and Burnover Investigation). Both of them investigated the fire weather, however, those two investigations gave short shrift to the causal wildland fire weather factors compared to the proximate and ongoing research from several prominent, recognized professionals and meteorologists, and meteorology forums, e.g. Cooperative Institute for Satellite Studies (CIMMS) University of Wisconsin-Madison (June 30, 2013) Yarnell Hill Fire in Arizona; Cliff Mass Weather Blog (July 2, 2013) The Yarnell Hill Fire: The Meteorological Origins; Wasatch Weather Weenies (July 2, 2013) Weather and the Yarnell Hill Fire, Arizona Republic Pulitzer Prize winner YH Fire article (2014), and the most recent and most comprehensive and enlightening work from the Prescott, AZ Embry-Riddle Aeronautical University (ERAU) researchers, Kaplan, M.L., C. N. James, J. Ising, M. R. Sinclair, Y.-L. Lin, A. Taylort, J. Riley, S. M.S. Karim, and J. Wiles (2021); The Multi-Scale Dynamics Organizing a Favorable Environment for Convective Density Currents That Redirected the Yarnell Hill Fire. Climate; and Ising, J., M. L. Kaplan, and Y.-L. Lin (2022) Effects of density current, diurnal heating, and local terrain on the mesoscale environment conducive to the Yarnell Hill Fire, Atmosphere.

But first the basics. Because this post concerns wildland fire weather, it is prudent to begin with the recognized Rules of Engagement ("10 & 18") and Entrapment Avoidance principles that specifically relate to fire weather for those Wildland Firefighters (WF), Municipal/Structural Firefighters (FF) engaged in wildland fire, as well as non-WF and FF readers alike.

There are Ten Standard Fire Orders and 18 Watch Out Situations, several of which deal exclusively with wildland fire weather. The first Fire Order states (1) Keep informed on fire weather conditions and forecasts. The three Watch Out Situations as guidelines specifically dealing with wildland fire weather state: (4) Unfamiliar with weather and local factors influencing fire behavior, (14) Weather becoming hotter and drier, and (15) Wind increases and/or changes direction. These are primarily addressed in the National Wildfire Coordinating Group (NWCG) Incident Response Pocket Guide (IRPG) "establishes standards for wildland fire incident response. The guide provides critical information on operational engagement, risk management, fire environment, all hazard response, and aviation management." The IRPG back page is comprised of these very same tried-and-trued Rules of Engagement.

In reality, because wildland Fire Weather determines fire behavior - from a wildland firefighter perspective - it is safe to say that all the other Watch Out Situations are affected in one way or another by fire weather during each of the firefighting and aircraft operations, even taking a nap near the fireline. Clearly, wildland fire weather determines wildland fire behavior and most wildfires will actually signal their intentions, thus making the knowledge, understanding, and utilization of the Rules of Engagement that much more critical.

The paper will hopefully contribute along with others, to our goal of reducing the number of inevitable wildland fire burnover, entrapments, fire shelter deployments, fatalities, and other tragic mishaps due to "incomplete lessons learned," one of the many notable conclusions derived from Dr. Dianne Vaughan and her extensive published research on the 1986 and 2003 Challenger and Columbia Space Shuttle disasters.