Simulation of winds affecting the Yarnell Hill Fire

This is an animation developed by Janice Coen, Ph.D., a Project Scientist at the National Center for Atmospheric Research in Boulder, Colorado. It simulates through a coupled weather-wildland fire environment model the spread of the Yarnell Hill Fire and the wind direction and speed. The arrows indicate the wind direction; the length of the arrows vary with the wind speed. On June 30, 2013 19 members of the Granite Mountain Hotshots were overrun by the fire when the winds from a thunderstorm cell north of the fire changed the direction of spread of the fire by about 90 degrees, surprising the firefighters on the south side of the fire, resulting in their entrapment.

See if you can tell when conditions worsened for the Hotshots.

Dr. Coen’s description of the simulation:

It begins at 2 am on 6/30/13. The fire is initialized in the model using the ~3 am VIIRS active fire detection map. Each frame is 1 minute apart, the sequence extends until 8:15 pm on 6/30. The fatality occurred around 4:45 PM. The color bar on the right indicates the heat flux (watts per square meter) from the fire, with more intensely burning areas in bright yellow and white, and less intensely burning areas in darker reds.
In the simulation, solar heating stirs up the boundary layer circulations throughout the day. Convection occurs in outer domains (not shown) to the northeast, creating high-based convective clouds as air flows south/southeast over the Mogollon Rim. Rain falls into a very dry boundary layer, creating a broad gust front that reaches the south edge of the fire at frame 936, which is 51 minutes after the fatality, so the simulated rush through the fatality site is about an hour slow.

The map below shows the approximate location of the fire at 4:30 p.m. on June 30, 2013, about 15 minutes before the Hotshots were entrapped at the deployment site (X) on the south side.

Yarnell Hill Fire, estimated perimeter at 4:30 p.m. June 30, 2014
Yarnell Hill Fire, estimated perimeter at 4:30 p.m. June 30, 2014. Source: Arizona State Forestry Division.

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Author: Bill Gabbert

After working full time in wildland fire for 33 years, he continues to learn, and strives to be a Student of Fire.

7 thoughts on “Simulation of winds affecting the Yarnell Hill Fire”

  1. EXCELLENT point,Robert! Could not have been better said!

    It goes well back to the S290 390 training and Fire Weather Agrculture Handbook 360

    It is pretty simple. Maybe even these supervisors need the equivalent of these every year to maintain their leadership credentials. After all, the introduction of those IFPM requirements for fire seems to have missed meteorology as to be as important as sharpening a tool or running a saw..

    Funny how these things keep getting missed

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  2. If you study for a pilot’s license, you will be taught that the wind will shift 90 degrees to the right when a front passes through, and that is what we see on this simulation. And it was this same exact shift due to a front passing through that killed a crew of hotshots in Colorado. When will the supervisors learn this simple law of meteorology, and change their tactics to accommodate for a change of wind directions 90 degrees to the right? How hard is this to learn and remember?

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  3. Amazing video graphics. I would have liked to see something like that for the South Canyon Fire.

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    1. Bret Butler and the folks at RMRS here in Missoula have done some work on the SCF using “WindWizard”. Google it and some sources will show up. Also, back in 1998, a bunch of us from RMRS & MTDC did a Technical Report on SCF Fire Behavior that has some simplified but user-friendly wind schematics overlayed on photos of the area. Still good for teaching fire classes and understanding what makes a fire move, I believe.

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      1. G’day Dick
        This event has encouraged me to promulgate a very simple message to our fire-fighters, running fires will take a (right hand turn – northern hemisphere) (left hand turn southern hemisphere) with the next wind change.

        Also, another message is beware of any situation where there is fire between you and storm activity.

        We teach paradigms. In SE Australia, the most dangerous fire weather is from the NW. Take a fire running with a SW wind, it is perceived that more dangerous flank is on the eastern side – the paradigm effect. However, the left hand turn rule will put the dangerous flank on the western side. Observation validates this for running fires at different parts of thepassage of fronts and troughs.

        It’s an important public safety message to sell. An interview after the 2009 Victorian fires – “The fire missed us, I thought we were safe!” Of course, this person was on the left hand side, and then the front went through.

        Locally with the 2013 Wambelong fire, a resident (don’t know how he survived) said it came from the south. “Fires don’t come from the south. Only from the north and west.”

        The implications are that each fire fighter needs to assess the direction of run, and determine if their escape routes are compromised.

        These two messages will be part of about 10 “Meteorological WATCHOUTS” . Some are inter-related, some unique to my region.

        Simple messages! And also re-inforce that the exception may apply! Always look for the exception.

        Cheers

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  4. Thank you, all, for your work on discovering what precipitated this tragic event. We may never have “the answer”, but we will learn more and more about what questions to ask, in the field and in retrospect.

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