Research Paper RMRS-RP-9
Fire Behavior Associated with the 1994 South Canyon Fire on Storm King Mountain, Colorado
Lightning ignited the South Canyon Fire on the afternoon of July 2, 1994. For the next 48 hours, the fire burned downslope in the leaves, twigs, and cured grasses covering the ground surface. By 1200 on July 4 the fire had burned approximately 3 acres. It continued to spread downslope through the day on July 5, covering approximately 50 acres by the end of the day. General fire activity consisted of low intensity downslope spread with intermittent flareups and short duration upslope runs in the fire's interior. The fire remained active through the night covering approximately 127 acres by morning on July 6.
On July 6 the fire continued to burn downslope through the surface fuels. At approximately 1520 a dry cold front passed over the area. Winds in the bottom of the drainage immediately west of the ignition point were estimated to be from the south (upcanyon) at 30 to 45 miles per hour. About 1555 several upslope fire runs occurred in the grass and conifers on the west-facing slope near the southwest corner of the fire's interior. Shortly after the crown fire runs, witnesses observed fire in the bottom of the drainage, directly west of the ridgetop ignition point. Pushed by the upcanyon winds, the fire in the drainage spread rapidly north. As this fire spread north and east, fuel, slope, and wind conditions combined to result in sustained fire spread through the live green Gambel oak canopy. The fire began burning as a high-intensity fast-moving continuous front. We estimate that the fire moved north up the drainage at about 3 feet per second. Steep slopes and strong west winds triggered frequent upslope (eastward) fire runs toward the top of the ridge. These upslope runs spread at 6 to 9 feet per second. A short time later the fire overran and killed 14 firefighters.
The South Canyon Fire tragically demonstrates the fire behavior that can occur given the appropriate combination of influencing factors. While fire behavior during the afternoon of July 6, 1994, can be characterized as extreme, it was normal and could be expected given the environmental conditions. Similar alignments of fire environment factors and the resulting fire behavior are not uncommon. The uncommon and tragic fact associated with this fire was that 14 firefighters were entrapped and killed by it.
This study focuses on two events: the blowup or transition from surface fire to a fire burning through the shrub canopy, and the fire behavior in the area identified as the West Flank that resulted in the deaths of 14 firefighters.
We identify three major factors that contributed to the blowup on the afternoon of July 6, 1994. The first was the presence of fire in the bottom of a steep narrow canyon. Second, strong upcanyon winds pushing the fire up the canyon and upslope. Third, the fire burning into the green (not previously underburned) Gambel oak canopy.
We have drawn a number of discussion points from the analysis. Some of these points will be readily apparent to firefighters. Others may be less evident. We believe that all are important. They are:
- Topography can dramatically influence local wind patterns.
- Vegetation and topography can reduce firefighter's ability to see a fire or other influencing factors.
- Current and past fire behavior often does not indicate the potential fire behavior that could occur.
- The longer a fire burns and the larger it gets the greater the likelihood of high-intensity fire behavior at some location around the perimeter.
- The transition from a slow-spreading, low-intensity fire to a fast-moving, high-intensity fire often occurs rapidly. This seems to surprise firefighters most often in live fuels.
- Escape route effectiveness should be considered in relation to potential maximum-intensity fire behavior rather than past or present fire behavior.
- The underburned Gambel oak did not contribute to the blowup. It was significant in that it did not provide a safety zone.
- Smoke can significantly reduce the firefighter's abilities to sense changes in fire behavior.
Title: Executive Summary: RMRS-RP-9
- Fire Behavior Associated with the 1994 South Canyon Fire on
Storm King Mountain, Colorado
Publish Date: February 5, 1999
Last Update: December 22, 2005
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