Sunday, June 12, 2011


At last night's community meeting with the fire team, Rich Harvey (an incident commander) emphasized the extremes which the firefighters are encountering in their dealings with the Horseshoe Two fire––unprecedented in his 32 years of experience. (Very likely, firefolk on the Wallow and Murphy Complex fires are finding the same extremes.) None of the professionals in this Type 1 fire team have ever seen such dry fuels.

Dead fuels are classified as 1-hour fuel (like grass), 10-hour fuel, 100-hour fuel, and 1000-hour fuel (a big, down log). 100-hour fuel takes 100 hours to dry out enough that it will burn. Here in the Chiricahuas, 100-hour fuel is burning in only 3 hours, and that low a value has never before been seen by this team.

The amount of strong wind is blowing minds. Red-flag day follows red-flag day, and today we have another. Strong winds push fire into strong uphill runs, creating crown fires that take out stands of trees. The amount of energy being released in one hour's worth of crown fire in the Chiricahua Mountains is the equivalent of the energy released by an atomic bomb. Such a fire chute occurred when Horseshoe Two raged in only 3 hours from the Saulsbury Saddle line, up to and through Onion Saddle.

Yet, even with those serious extremes, a mosaic burn is being achieved in many areas through use of techniques that moderate the fire's growth and spread, including lighting ridge fires at night to back slowly down into canyons, and meet the oncoming fire before it rushes up those same ridges. Of all the techniques tried by the teams so far, the backburning is working best on this fire, under these conditions. Moderating the fire not only promotes a mosaic burn, but also protects soils for future regrowth.

A photo of the junction of Rustler and Barfoot roads showed many of the big trees still intact, so some of the mosaic burn still happened, even in this intensely-burned high country.

We also learned more about one crew boss's experience as they battled the holocaust in Whitetail Canyon, a situation vastly complicated by constantly-changing high winds that demanded the utmost in quick responses and flexibility. Plans had been carefully laid for protecting Whitetail, including a line laid by hand that joined the back road into Chiricahua National Monument, a dozer line, and structure protection. Then a big blast of wind from the south changed everything. One juniper flared and sent firebrands in all directions, and fire jumped the lines. A column of blazing hot smoke rose thousands of feet into the air, then rolled and started to collapse. That is a firefighter's nightmare, because a huge collapsing column sends fire everywhere as superheated smoke hits the ground. The worst-case scenario was narrowly avoided in Whitetail when another big wind gust suddenly straightened the column. Firefighters were beaten back from Whitetail by these volatile and dangerous conditions; when they were able to return, they found that the sprinklers and other structure protection in place had saved 18 of the 20 residences there.

A similar extreme event happened further south along the western flank of the fire, when the fire was being pushed upcanyon by very strong wind, which suddenly entered another canyon with different orientation, and sheared the fire column 180ยบ, setting the entire column (thousands of feet high) to spinning. Suddenly the fire turned into the faces of the crew there.

These events involving collapsing columns of fire and smoke are quite rare, and this is only the second time in this operation chief's career that he has ever witnessed one.

One photo graphically illustrated why residents and other people are not yet being allowed back into the burned areas: a gaping hole where a tree once stood was still burning deep in the ground. Fires can burn into big root systems for days, making the terrain dangerous.

More than 1200 fire personnel are now working on Horseshoe Two. They are on the lines 24 hours a day, in two shifts. People in the planning department have longer days than those out on the fire lines: they are spending 16 - 20 hours a day working on strategy, as the fire moves and conditions constantly change.

The new planned perimeter lines are out in the flats, with much lower fuel supply and easy terrain. There they should finally be able to fully contain this fire. Rich Harvey said that they estimate that Horseshoe Two is now 45% contained. He is cautious about calling a fire contained because, "If I say it's contained and something happens, they name it after me and I'm in big trouble."

Other agencies help and advise the fire teams. US Forest Service staff are interested in resource protection, and they make sure that important details like the locations of crucial habitat and Spotted Owl nests are considered when fire plans are formulated.

The fire bosses said that two weeks of working on a fire like Horseshoe Two is worth years of experience of working on more normal fires.

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