Fire Behavior Associated with the 1994 South Canyon Fire on Storm King Mountain, Colorado
This section is a short summary of the fire environment on the afternoon of July 6, 1994. First we discuss the topography. Next we discuss the condition of the vegetation or fuels in the area. Finally, we summarize the long-term and short-term weather related factors that influenced the fire behavior.
For the purposes of this study, we have attempted to use the same location names as were used in the original investigation report. However, we have identified a few previously unnamed areas. In most cases we identify the specific locations by a dominant geographical feature.
The fire occurred in a topographically complex area. The highest peak in the area, Storm King Mountain, is over 8,700 feet in elevation. The terrain south of the peak falls in a series of steep rugged broken ravines, gullies, and ridges to the Colorado River (elevation approximately 5,680 feet). Figures 4 and 5 present an aerial photograph and topographical map of the fire area. Figures 3, 6, 7, and 8 are aerial oblique photographs of the fire site from different view angles.
Main Ridge—Up to the afternoon of July 6, 1994, the South Canyon Fire burned on the southwest side of Storm King Mountain. One of the main ridges between the mountain and the Colorado River Gorge is locally known as Hellsgate Ridge, we refer to it as the Main Ridge. The northeastern end of the Main Ridge begins as a saddle at the southern base of Storm King Mountain. The two firefighters working helitack were killed in a steep rocky chute northwest of this area. From the saddle the Main Ridge runs to the southwest for about 3,700 feet where it abruptly ends at the Colorado River Gorge.
Ignition Point—A lightning strike to the top of the southwest-most knob of the Main Ridge (elevation 6,980 feet) ignited the South Canyon Fire. To the south from the Ignition Point the terrain falls steeply (about a 55 percent slope) to Interstate 70 and the Colorado River.
East and West Drainages—The Main Ridge is flanked on the east and west by two north-south oriented drainages. These drainages are referred to as the East and West Drainages. Both drainages were formed by erosion of the sandstone rock and soil. Fine sand fills the bottom of the drainages with intermittent large sandstone boulders. The West Drainage follows a twisting path north from the Colorado River Gorge. The bottom of the West Drainage is a steep-sided (80 percent slope) ravine. The West Drainage channeled air from the Colorado River Gorge north to the base of Storm King Mountain. The fire changed from a backing surface fire moving down the slope to a fast spreading fire burning upslope and upcanyon through the shrub and tree canopies in the West Drainage. Surviving firefighters exited via the East Drainage. The fire burned through the East Drainage about 30 minutes after the firefighters exited it.
Lunch Spot and Spur Ridges—Two spur ridges that are important to the narrative extend west from the Main Ridge down into the West Drainage. The southernmost ridge, referred to as the Lunch Spot Ridge, was where the firefighters who had been building fireline down the West Flank of the fire ate lunch on the afternoon of July 6 (fig. 3 through 6 and 8). Eight smokejumpers deployed and survived in fire shelters on the upper portion of the Lunch Spot Ridge during the afternoon of July 6, 1994. One smokejumper survived near the Lunch Spot without deploying a fire shelter.
A second smaller ridge, located about 1,400 feet north of the Lunch Spot Ridge, we call the Spur Ridge. The Spur Ridge serves as a point of reference when discussing firefighter, helicopter, and fire location and movement.
Helispots H-1 and H-2—Two helispots were constructed on the Main Ridge. The first helispot (designated H-1) was constructed on July 5 and was at the junction of the Main Ridge and Lunch Spot Ridge at about 7,000 feet elevation on an unnamed knob. It consisted of an area approximately 50 feet in diameter that was cleared of brush and trees. Stumps and ground litter remained. A second helispot (H-2) was constructed on the morning of July 6. H-2 was at 6,760 feet elevation and was about 1/4 mile north of H-1. This helispot was smaller than H-1 and was situated in a small saddle from which the brush had been cleared away.
Double Draws—The southwest face of the Main Ridge near H-1 falls steeply (approximately 55 percent slope) dropping more than 1,000 feet in elevation to the bottom of the West Drainage. The Double Draws are on this steep west-facing slope. They consist of two steep chimneylike gullies leading into the West Drainage. They originate approximately one-third the way down the slope below H-1 and were formed by erosion of the loose soil (fig. 5 and 8). Several crown fire runs occurred south of the Double Draws shortly before the fire suddenly began burning up the West Drainage on the afternoon of July 6, 1994.
Bowl—A small bowl (approximately 1/2 acre) is in the bottom of the West Drainage about 250 feet north of the intersection of the Double Draws and the West Drainage. This area is referred to as the Bowl. The accumulation of live and dead fuel in the Bowl contributed to the development of the fire that spread up the West Drainage.
West Bench—Northeast of the junction of the West Drainage and the Lunch Spot Ridge is the West Bench. This area is approximately 80 feet above the bottom of the West Drainage. The West Bench is approximately 150 feet wide and 450 feet long with the long side oriented parallel to the West Drainage. While not flat (approximately 15 percent slope), the West Bench is significantly less steep than the slopes on either side of it. Gambel oak with grassy openings was the dominant vegetation on the West Bench. Gambel oak completely covered the slopes between the West Bench and the Main Ridge.
West Flank Fireline—This fireline is approximately 2,100 feet long with the Lunch Spot at its southernmost point. From the Main Ridge, the West Flank Fireline leads west down the steep (about 55 percent) slope for 300 feet. From the base of this first steep pitch the fireline continues, at a much flatter slope (about 10 percent), another 380 feet down and across the slope to the Spur Ridge. It leads over the Spur Ridge, turns to the southwest, and follows a contour route across the West Flank slope for about 800 feet. From this point it contours 400 feet diagonally across and down the slope, leading generally southwest, and then climbs 200 feet up a 65 percent slope to the Lunch Spot. Several points of interest on the West Flank Fireline are identified by their major topographical features. Distance along the fireline from the junction of the Main Ridge and the Fireline are given in parentheses. The points are: the Zero Point (0 feet); the Fatality Site (120 to 280 feet); the Tree (200 feet); the Draw at the base of the first steep pitch in the fireline (445 feet); the Spur Ridge (680 feet); the Stump (850 feet); two other locations (1,450 and 1,880 feet) are important to the fire chronology presented later. All of these points are shown in figure 3. All distances are detailed in appendix B, table B-2.
Zero Point—The junction of the Main Ridge and the top of the fireline constructed on the West Flank is an important geographical location when specifying specific firefighter locations and movement. For the purposes of this report, it is referred to as the Zero Point. We found it helpful to reference distances along the Main Ridge and the fireline from this point. For example, helispot H-1 is 790 feet south along the Main Ridge from the Zero Point and helispot H-2 is 560 feet north along the Main Ridge from the Zero point.
Drop Zone—The smokejumper Drop Zone was near the Saddle on the north end of the Main Ridge (approximately 1,000 feet north of H-2).
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